Article This article is protected by copyright. All rights reserved.
Abstract
We have observed both minor-arc (R1) and major-arc (R2) Rayleigh waves for the largest marsquake (magnitude
of 4.7 ± 0.2) ever recorded. Along the R1 path (in the lowlands), inversion results show that a simple, two-layer
model with an interface located at 21 - 29 km and an upper crustal shear-wave velocity of 3.05 - 3.17 km/s can fit the
group velocity measurements. Along the R2 path, observations can be explained by upper crustal thickness models
constrained from gravity data and upper crustal shear-wave velocities of 2.61 - 3.27 km/s and 3.28 - 3.52 km/s in the
lowlands and highlands, respectively. The shear-wave velocity being faster in the highlands than in the lowlands
indicates the possible existence of sedimentary rocks, and relatively higher porosity in the lowlands.
Martian soil as revealed by ground-penetrating radar at the Tianwen-1 landing...Sérgio Sacani
Much of the Martian surface is covered by a weathering layer (regolith or soil) produced
by long-term surface processes such as impact gardening, eolian erosion, water weathering,
and glacial modifications. China’s first Martian mission, Tianwen-1, employed the Mars
Rover Penetrating Radar (RoPeR) to unveil the detailed structure of the regolith layer and
assess its loss tangent. The RoPeR radargram revealed the local regolith layer to be highly
heterogeneous and geologically complex and characterized by structures that resemble partial
or complete crater walls and near-surface impact lenses at a very shallow depth. However,
comparable radar data from the Lunar far side are rather uniform, despite the two surfaces
being geologically contemporary. The close-to-surface crater presented in this study shows
no detectable surface expression, which suggests an accelerated occultation rate for small
craters on the surface of Mars as compared to the rate on the Moon. This is probably due to
the relentless eolian processes on the Martian surface that led to the burial of the crater and
thus shielded it from further erosion. The high loss tangent indicates that the regolith at the
Tianwen-1 landing site is not dominated by water ice.
This document describes experiments simulating volcanic flooding on the Moon using lunar topography data. Three similarly sized regions were artificially flooded: 1) heavily cratered terrain, 2) Hertzsprung basin, and 3) the Central Highlands. As flooding progressed, small craters were buried first followed by larger craters. Comparing the results from point source and ubiquitous flooding showed little difference in the volume of lava added or changes to crater size distributions over time. The experiments provide insights into estimating lava volumes involved in large scale resurfacing events on terrestrial planets.
1) Global climate models that include sophisticated cloud schemes show that tidally locked planets can develop thick water clouds near the substellar point due to strong convection. These clouds greatly increase the planetary albedo and stabilize temperatures, allowing habitability at twice the stellar flux previously thought possible.
2) The cloud feedback is stabilizing, as higher stellar flux produces stronger convection and higher albedos. Substellar clouds can block outgoing radiation, reducing the day-night temperature contrast.
3) Non-tidally locked planets do not experience this stabilizing cloud feedback, as clouds only form over parts of the tropics and mid-latitudes. Their albedo decreases with increasing stellar flux, producing a destabil
One tenth solar_abundances_along_the_body_of-the_streamSérgio Sacani
This document summarizes a study that analyzed spectra from four background quasars to measure the chemical abundances along the Magellanic Stream. Two key findings are:
1) The sightlines toward RBS 144 and NGC 7714 yielded metallicities of around 0.1 times the solar value, indicating a uniform low abundance along the main body of the Stream. This supports models where the Stream was stripped from the SMC around 1-2.5 billion years ago when the SMC had a metallicity of around 0.1 solar.
2) A higher metallicity of around 0.5 solar was found in the inner Stream toward Fairall 9, sampling a filament traced to the LMC. This shows the bifurc
A Tectonic Origin for the Largest Marsquake Observed by InSightSérgio Sacani
The S1222a marsquake detected by InSight on 4 May 2022 was the largest of the mission, at 𝐴𝐴𝐴𝐴𝐴𝐴𝑀𝑀𝑤𝑤 4.7. Given its resemblance to two other large seismic events (S1000a and S1094b), which were associated with the formation of fresh craters, we undertook a search for a fresh crater associated with S1222a. Such a crater would be expected to be ∼300 m in diameter and have a blast zone on the order of 180 km across. Orbital images were targeted and searched as part of an international, multi-mission effort. Comprehensive analysis of the area using low- and medium-resolution images reveals no relevant transient atmospheric phenomena and no fresh blast zone. High-resolution coverage of the epicentral area from most spacecraft are more limited, but no fresh crater or other evidence of a new impact have been identified in those images either. We thus conclude that the S1222a event was highly likely of tectonic origin
The nonmagnetic nucleus_of_comet_67_p_churyumov_gerasimenkoSérgio Sacani
Artigo descreve como a sonda Rosetta e o módulo Philae descobriram que o cometa Churyumov-Gerasimenko não é magnetizado, contrariando uma teoria da formação do Sistema Solar.
Martian soil as revealed by ground-penetrating radar at the Tianwen-1 landing...Sérgio Sacani
Much of the Martian surface is covered by a weathering layer (regolith or soil) produced
by long-term surface processes such as impact gardening, eolian erosion, water weathering,
and glacial modifications. China’s first Martian mission, Tianwen-1, employed the Mars
Rover Penetrating Radar (RoPeR) to unveil the detailed structure of the regolith layer and
assess its loss tangent. The RoPeR radargram revealed the local regolith layer to be highly
heterogeneous and geologically complex and characterized by structures that resemble partial
or complete crater walls and near-surface impact lenses at a very shallow depth. However,
comparable radar data from the Lunar far side are rather uniform, despite the two surfaces
being geologically contemporary. The close-to-surface crater presented in this study shows
no detectable surface expression, which suggests an accelerated occultation rate for small
craters on the surface of Mars as compared to the rate on the Moon. This is probably due to
the relentless eolian processes on the Martian surface that led to the burial of the crater and
thus shielded it from further erosion. The high loss tangent indicates that the regolith at the
Tianwen-1 landing site is not dominated by water ice.
This document describes experiments simulating volcanic flooding on the Moon using lunar topography data. Three similarly sized regions were artificially flooded: 1) heavily cratered terrain, 2) Hertzsprung basin, and 3) the Central Highlands. As flooding progressed, small craters were buried first followed by larger craters. Comparing the results from point source and ubiquitous flooding showed little difference in the volume of lava added or changes to crater size distributions over time. The experiments provide insights into estimating lava volumes involved in large scale resurfacing events on terrestrial planets.
1) Global climate models that include sophisticated cloud schemes show that tidally locked planets can develop thick water clouds near the substellar point due to strong convection. These clouds greatly increase the planetary albedo and stabilize temperatures, allowing habitability at twice the stellar flux previously thought possible.
2) The cloud feedback is stabilizing, as higher stellar flux produces stronger convection and higher albedos. Substellar clouds can block outgoing radiation, reducing the day-night temperature contrast.
3) Non-tidally locked planets do not experience this stabilizing cloud feedback, as clouds only form over parts of the tropics and mid-latitudes. Their albedo decreases with increasing stellar flux, producing a destabil
One tenth solar_abundances_along_the_body_of-the_streamSérgio Sacani
This document summarizes a study that analyzed spectra from four background quasars to measure the chemical abundances along the Magellanic Stream. Two key findings are:
1) The sightlines toward RBS 144 and NGC 7714 yielded metallicities of around 0.1 times the solar value, indicating a uniform low abundance along the main body of the Stream. This supports models where the Stream was stripped from the SMC around 1-2.5 billion years ago when the SMC had a metallicity of around 0.1 solar.
2) A higher metallicity of around 0.5 solar was found in the inner Stream toward Fairall 9, sampling a filament traced to the LMC. This shows the bifurc
A Tectonic Origin for the Largest Marsquake Observed by InSightSérgio Sacani
The S1222a marsquake detected by InSight on 4 May 2022 was the largest of the mission, at 𝐴𝐴𝐴𝐴𝐴𝐴𝑀𝑀𝑤𝑤 4.7. Given its resemblance to two other large seismic events (S1000a and S1094b), which were associated with the formation of fresh craters, we undertook a search for a fresh crater associated with S1222a. Such a crater would be expected to be ∼300 m in diameter and have a blast zone on the order of 180 km across. Orbital images were targeted and searched as part of an international, multi-mission effort. Comprehensive analysis of the area using low- and medium-resolution images reveals no relevant transient atmospheric phenomena and no fresh blast zone. High-resolution coverage of the epicentral area from most spacecraft are more limited, but no fresh crater or other evidence of a new impact have been identified in those images either. We thus conclude that the S1222a event was highly likely of tectonic origin
The nonmagnetic nucleus_of_comet_67_p_churyumov_gerasimenkoSérgio Sacani
Artigo descreve como a sonda Rosetta e o módulo Philae descobriram que o cometa Churyumov-Gerasimenko não é magnetizado, contrariando uma teoria da formação do Sistema Solar.
Published by Mining Matters this secondary school thematic resources uses the topic of diamonds to explore Earth's structure and process, the mining cycle as well a careers in the minerals industry.
The 21 activities in Discovering Diamonds bring in elements from every area of Earth Science – from earthquakes to environment, cratons to chemicals. Activities are presented in sequence in five topics, starting with the large-scale structure of the earth, moving into tectonic and surficial processes, and finishing with a look at the mining industry, including exploration, mining, processing, and mining’s importance to Canadians.
Students will learn about Canada’s world-class diamond-bearing deposits, diamond formation, and the modern technology being applied to the discovery, extraction, and processing of diamonds. The diamond industry uses cutting-edge technology; current information about this industry makes a valuable addition to the school Earth Science curriculum.
This document discusses seismic velocities and how they are affected by rock properties. It contains the following key points:
1. Seismic waves can be classified as body waves, which travel through rock, and surface waves, which travel along surfaces. Body waves are P waves and S waves, with P waves traveling faster.
2. The velocities of P and S waves are determined by elastic properties of the material like density, bulk modulus, and shear modulus. S wave velocity is always lower than P wave velocity.
3. Seismic velocities increase with depth and density in the subsurface generally, though velocity can decrease if gas is replaced by brine in rocks. Lateral velocity changes can cause seismic artifacts like pull up
Mars surface radiation_environment_measured_with_curiositySérgio Sacani
The Radiation Assessment Detector on the Curiosity rover measured the radiation environment on the surface of Mars over approximately 300 days. It found:
1) The average absorbed radiation dose from galactic cosmic rays was 0.210 mGy/day, varying due to atmospheric and solar conditions.
2) An additional absorbed dose of about 50 μGy was measured from a solar particle event.
3) Extrapolating the surface measurements, the absorbed dose was estimated to be 76 mGy/year at 1 meter below the surface, decreasing substantially at greater depths.
The xmm newton-view_of_the_central_degrees_of_the_milk_waySérgio Sacani
Novas imagens do Observatório de Raios-X XMM-Newton da ESA revelaram alguns dos processos mais intensos que acontecem no coração da nossa Via Láctea.
As fontes brilhantes e pontuais que se destacam por toda imagem indicam os sistemas estelares binários onde uma das estrelas atingiu o final de sua vida, desenvolvendo para um objeto compacto e denso – uma estrela de nêutrons ou um buraco negro.
A região central da Via Láctea também contém jovens estrelas e aglomerados estelares e algumas dessas fontes são visíveis como pontos brancos e vermelhos brilhando na imagem, que se espalha por 1000 anos-luz.
A maior parte da ação ocorre no centro, onde nuvens difusas de gás estão sendo cavadas por ventos poderosos soprados por estrelas jovens, bem como por supernovas.
Galaxy dynamics and the mass density of the universeSérgio Sacani
Dynamical evidence accumulated over the
past 20 years has convinced astronomers that luminous matter
in a spiral galaxy constitutes no more than 10% of the mass of
a galaxy. An additional 90% is inferred by its gravitational
effect on luminous material. Here I review recent observations
concerning the distribution of luminous and nonluminous
matter in the Milky Way, in galaxies, and in galaxy clusters.
Observations of neutral hydrogen disks, some extending in
radius several times the optical disk, confirm that a massive
dark halo is a major component of virtually every spiral. A
recent surprise has been the discovery that stellar and gas
motions in ellipticals are enormously complex. To date, only for
a few spheroidal galaxies do the velocities extend far enough to
probe the outer mass distribution. But the diverse kinematics
of inner cores, peripheral to deducing the overall mass distribution,
offer additional evidence that ellipticals have acquired
gas-rich systems after initial formation. Dynamical results are
consistent with a low-density universe, in which the required
dark matter could be baryonic. On smallest scales of galaxies
[10 kiloparsec (kpc); H. = 50 kmsec'lmegaparsec'11 the
luminous matter constitutes only 1% of the closure density. On
scales greater than binary galaxies (i.e., .100 kpc) all systems
indicate a density -10% of the closure density, a density
consistent with the low baryon density in the universe. If
large-scale motions in the universe require a higher mass
density, these motions would constitute the first dynamical
evidence for nonbaryonic matter in a universe of higher
density.
Detection of intact lava tubes at Marius Hills on the Moon by SELENE (Kaguya)...Sérgio Sacani
Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon’s composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00–15.005°N, 301.85–304.01°E around the MHH and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille.
Basic Components of Seismo-Ionospheric Couplingdavohawrami
The document provides an overview of the basic components of seismo-ionospheric coupling. It discusses earth structure and seismology, including tectonic plates and earthquake magnitude scales. It also covers the atmosphere, ionization sources, and characteristics of the ionosphere. Key precursors of earthquakes mentioned are changes in radon gas emanation, electric fields, and geochemical factors. The conclusion states that radon emanation may provide the primary link between seismic activity and the ionosphere.
Pawan Kumar Relativistic jets in tidal disruption eventsBaurzhan Alzhanov
- Fast radio bursts (FRBs) are short, intense radio pulses that last about 1 millisecond. One FRB source produced multiple outbursts over several years.
- The leading model is that FRBs originate from young, highly magnetic neutron stars called magnetars. Charged particles are accelerated by magnetic reconnection, producing coherent curvature radiation observed as FRBs.
- FRBs provide insights into neutron star physics and energetic processes in magnetar magnetospheres. Predictions include observing FRB-like bursts at higher frequencies.
This document summarizes the discovery of an Earth-mass planet orbiting the star Alpha Centauri B. The planet, with a minimum mass similar to Earth, has an orbital period of 3.236 days and is located about 0.04 astronomical units from the star. High-precision radial velocity measurements from the HARPS spectrograph revealed the planet's signal, making it the lightest planet detected around a solar-type star. The discovery demonstrates that current techniques can detect potentially habitable super-Earth planets around Sun-like stars and habitable Earth-like planets around cooler stars.
An Earth-mass planet orbiting a Centauri BCarlos Bella
1) Researchers detected an Earth-mass planet orbiting the star Alpha Centauri B.
2) The planet has a minimum mass similar to Earth and orbits its star with a period of 3.236 days, within 0.04 astronomical units.
3) This makes it the lightest planet detected orbiting a Sun-like star and the closest exoplanet to our solar system found to date.
Artigo relata como a Terra sofreu com os impactos de ateroides a 4 bilhões de anos atrás, e como a superfície do planeta foi remodelada e os oceanos formados.
1) The document provides a summary of a course on high-energy astrophysics that the author took. It discusses various topics covered in the course including accretion disks, pulsars, black holes, supernovae, and more.
2) The author argues that high-energy astrophysics is important for understanding the universe and requests that the provost offer a similar course at their university.
3) Key concepts in high-energy astrophysics discussed include accretion and its relation to luminosity, binary star systems, properties of neutron stars and black holes, and x-ray emissions from astrophysical phenomena like supernovae.
The most luminous_galaxies_discovered_by_wiseSérgio Sacani
This document presents a sample of 20 extremely luminous galaxies discovered by the Wide-field Infrared Survey Explorer (WISE). Five of these galaxies have infrared luminosities exceeding 1014 solar luminosities, the highest infrared luminosity threshold yet observed. They were selected using criteria requiring weak or no detection in the first two WISE bands but strong detections in the third and fourth bands. Spectral energy distribution modeling suggests their high luminosities are powered by obscured active galactic nuclei with hot dust temperatures around 450 Kelvin. The existence of such luminous galaxies at redshifts above 3 provides constraints on the early growth of supermassive black holes through rapid accretion.
Predictions of the_atmospheric_composition_of_gj_1132_bSérgio Sacani
GJ 1132 b is a nearby Earth-sized exoplanet transiting an M dwarf, and is amongst the most highly
characterizable small exoplanets currently known. In this paper we study the interaction of a magma
ocean with a water-rich atmosphere on GJ 1132b and determine that it must have begun with more
than 5 wt% initial water in order to still retain a water-based atmosphere. We also determine the
amount of O2
that can build up in the atmosphere as a result of hydrogen dissociation and loss.
We find that the magma ocean absorbs at most ∼ 10% of the O2 produced, whereas more than
90% is lost to space through hydrodynamic drag. The most common outcome for GJ 1132 b from our
simulations is a tenuous atmosphere dominated by O2
, although for very large initial water abundances
atmospheres with several thousands of bars of O2
are possible. A substantial steam envelope would
indicate either the existence of an earlier H2
envelope or low XUV flux over the system’s lifetime. A
steam atmosphere would also imply the continued existence of a magma ocean on GJ 1132 b. Further
modeling is needed to study the evolution of CO2
or N2
-rich atmospheres on GJ 1132 b.
This document presents evidence that massive galaxies at redshift 2.2 (~3 billion years after the Big Bang) undergo an "inside-out quenching" process, where star formation is quenched first in the inner regions and later in the outer disks. High-resolution observations of 22 star-forming galaxies show that the most massive galaxies already have dense bulges similar to local spheroids, while still actively forming stars in their outer disks. The data suggests star formation is suppressed from the inside out on timescales of less than 1 Gyr in the centers and up to a few Gyr in the outer disks, as an "inside-out quenching wave" propagates through the galaxies. This provides insights into how
First Observation of the Earth’s Permanent FreeOscillation s on Ocean Bottom ...Sérgio Sacani
The Earth’s hum is the permanent free oscillations of the Earth recorded in the absence ofearthquakes, at periods above 30 s. We present the first observations of its fundamental spheroidaleigenmodes on broadband ocean bottom seismometers (OBSs) in the Indian Ocean. At the ocean bottom,the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In ourexperiment, data are also affected by electronic glitches. We remove these signals from the seismic traceby subtracting average glitch signals; performing a linear regression; and using frequency-dependentresponse functions between pressure, horizontal, and vertical seismic components. This reduces the longperiod noise on the OBS to the level of a good land station. Finally, by windowing the autocorrelation toinclude only the direct arrival, the first and second orbits around the Earth, and by calculating its Fouriertransform, we clearly observe the eigenmodes at the ocean bottom.
This document summarizes evidence that argues against the hypothesis of a "lunar terminal cataclysm" approximately 3.9 billion years ago. It analyzes dating of lunar highland rocks and meteorites, finding they do not show a prominent peak at 3.9 billion years as expected, but rather a more uniform distribution of ages. Analysis of the cratering record of lunar basins also argues against a spike in the lunar bombardment rate at that time. Modeling of impact melt production and redistribution across the lunar surface further casts doubt on there having been a major cataclysm 3.9 billion years ago as hypothesized.
Evidence for Long-Lasting Electrical Leader Discharges in NonSpecular Meteor ...researchinventy
Unusual, non-specular, fast-movingmeteortrail echoes are observed in the summer polar upper mesosphere near 90 km.Usually, at mid-latitudes, field-aligned irregularities cause non-specular trails, while in the polar region long-lasting irregularities are possibly sustained by charged meteor dust.The unusual meteor trails propagate downward and upward at speeds of 3.3-6.4 kms-1 along a slanted path length of 10.4 km between 87-93 km altitudes, merging in the middle and lasting for 8-10s. Here we propose that an electrical discharge is responsible for these trails. The corresponding horizontal electric field for the observed speeds is estimated up to 16.3 Vm-1 at 90 km.Both the long-lasting merging of two fast-moving plasma trails and the modest speed compared to those (~104 -105 ms -1 ) of lightning leader process and of jets (< 400 ms) occurring above thunderclouds likely suggest a new type of meteor-trail leader discharge occurring in the summer polar upper mesosphere
The habitability of Proxima Centauri b - I. Irradiation, rotation and volatil...Sérgio Sacani
Proxima b is a planet with a minimum mass of 1.3 M⊕ orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass,
active star and the Sun’s closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b
and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet
and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time
evolution of the star’s spectrum, which is essential for modeling the flux received over Proxima b’s lifetime. We also show that Proxima
b’s obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet’s eccentricity and
level of triaxiality. Next we consider the evolution of Proxima b’s water inventory. We use our spectral energy distribution to compute
the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find
that Proxima b is likely to have lost less than an Earth ocean’s worth of hydrogen (EOH) before it reached the HZ 100–200 Myr after
its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We
conclude that Proxima b is a viable candidate habitable planet.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
More Related Content
Similar to Different Martian Crustal Seismic Velocities across the Dichotomy Boundary from Multi-Orbiting Surface Waves
Published by Mining Matters this secondary school thematic resources uses the topic of diamonds to explore Earth's structure and process, the mining cycle as well a careers in the minerals industry.
The 21 activities in Discovering Diamonds bring in elements from every area of Earth Science – from earthquakes to environment, cratons to chemicals. Activities are presented in sequence in five topics, starting with the large-scale structure of the earth, moving into tectonic and surficial processes, and finishing with a look at the mining industry, including exploration, mining, processing, and mining’s importance to Canadians.
Students will learn about Canada’s world-class diamond-bearing deposits, diamond formation, and the modern technology being applied to the discovery, extraction, and processing of diamonds. The diamond industry uses cutting-edge technology; current information about this industry makes a valuable addition to the school Earth Science curriculum.
This document discusses seismic velocities and how they are affected by rock properties. It contains the following key points:
1. Seismic waves can be classified as body waves, which travel through rock, and surface waves, which travel along surfaces. Body waves are P waves and S waves, with P waves traveling faster.
2. The velocities of P and S waves are determined by elastic properties of the material like density, bulk modulus, and shear modulus. S wave velocity is always lower than P wave velocity.
3. Seismic velocities increase with depth and density in the subsurface generally, though velocity can decrease if gas is replaced by brine in rocks. Lateral velocity changes can cause seismic artifacts like pull up
Mars surface radiation_environment_measured_with_curiositySérgio Sacani
The Radiation Assessment Detector on the Curiosity rover measured the radiation environment on the surface of Mars over approximately 300 days. It found:
1) The average absorbed radiation dose from galactic cosmic rays was 0.210 mGy/day, varying due to atmospheric and solar conditions.
2) An additional absorbed dose of about 50 μGy was measured from a solar particle event.
3) Extrapolating the surface measurements, the absorbed dose was estimated to be 76 mGy/year at 1 meter below the surface, decreasing substantially at greater depths.
The xmm newton-view_of_the_central_degrees_of_the_milk_waySérgio Sacani
Novas imagens do Observatório de Raios-X XMM-Newton da ESA revelaram alguns dos processos mais intensos que acontecem no coração da nossa Via Láctea.
As fontes brilhantes e pontuais que se destacam por toda imagem indicam os sistemas estelares binários onde uma das estrelas atingiu o final de sua vida, desenvolvendo para um objeto compacto e denso – uma estrela de nêutrons ou um buraco negro.
A região central da Via Láctea também contém jovens estrelas e aglomerados estelares e algumas dessas fontes são visíveis como pontos brancos e vermelhos brilhando na imagem, que se espalha por 1000 anos-luz.
A maior parte da ação ocorre no centro, onde nuvens difusas de gás estão sendo cavadas por ventos poderosos soprados por estrelas jovens, bem como por supernovas.
Galaxy dynamics and the mass density of the universeSérgio Sacani
Dynamical evidence accumulated over the
past 20 years has convinced astronomers that luminous matter
in a spiral galaxy constitutes no more than 10% of the mass of
a galaxy. An additional 90% is inferred by its gravitational
effect on luminous material. Here I review recent observations
concerning the distribution of luminous and nonluminous
matter in the Milky Way, in galaxies, and in galaxy clusters.
Observations of neutral hydrogen disks, some extending in
radius several times the optical disk, confirm that a massive
dark halo is a major component of virtually every spiral. A
recent surprise has been the discovery that stellar and gas
motions in ellipticals are enormously complex. To date, only for
a few spheroidal galaxies do the velocities extend far enough to
probe the outer mass distribution. But the diverse kinematics
of inner cores, peripheral to deducing the overall mass distribution,
offer additional evidence that ellipticals have acquired
gas-rich systems after initial formation. Dynamical results are
consistent with a low-density universe, in which the required
dark matter could be baryonic. On smallest scales of galaxies
[10 kiloparsec (kpc); H. = 50 kmsec'lmegaparsec'11 the
luminous matter constitutes only 1% of the closure density. On
scales greater than binary galaxies (i.e., .100 kpc) all systems
indicate a density -10% of the closure density, a density
consistent with the low baryon density in the universe. If
large-scale motions in the universe require a higher mass
density, these motions would constitute the first dynamical
evidence for nonbaryonic matter in a universe of higher
density.
Detection of intact lava tubes at Marius Hills on the Moon by SELENE (Kaguya)...Sérgio Sacani
Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon’s composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00–15.005°N, 301.85–304.01°E around the MHH and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille.
Basic Components of Seismo-Ionospheric Couplingdavohawrami
The document provides an overview of the basic components of seismo-ionospheric coupling. It discusses earth structure and seismology, including tectonic plates and earthquake magnitude scales. It also covers the atmosphere, ionization sources, and characteristics of the ionosphere. Key precursors of earthquakes mentioned are changes in radon gas emanation, electric fields, and geochemical factors. The conclusion states that radon emanation may provide the primary link between seismic activity and the ionosphere.
Pawan Kumar Relativistic jets in tidal disruption eventsBaurzhan Alzhanov
- Fast radio bursts (FRBs) are short, intense radio pulses that last about 1 millisecond. One FRB source produced multiple outbursts over several years.
- The leading model is that FRBs originate from young, highly magnetic neutron stars called magnetars. Charged particles are accelerated by magnetic reconnection, producing coherent curvature radiation observed as FRBs.
- FRBs provide insights into neutron star physics and energetic processes in magnetar magnetospheres. Predictions include observing FRB-like bursts at higher frequencies.
This document summarizes the discovery of an Earth-mass planet orbiting the star Alpha Centauri B. The planet, with a minimum mass similar to Earth, has an orbital period of 3.236 days and is located about 0.04 astronomical units from the star. High-precision radial velocity measurements from the HARPS spectrograph revealed the planet's signal, making it the lightest planet detected around a solar-type star. The discovery demonstrates that current techniques can detect potentially habitable super-Earth planets around Sun-like stars and habitable Earth-like planets around cooler stars.
An Earth-mass planet orbiting a Centauri BCarlos Bella
1) Researchers detected an Earth-mass planet orbiting the star Alpha Centauri B.
2) The planet has a minimum mass similar to Earth and orbits its star with a period of 3.236 days, within 0.04 astronomical units.
3) This makes it the lightest planet detected orbiting a Sun-like star and the closest exoplanet to our solar system found to date.
Artigo relata como a Terra sofreu com os impactos de ateroides a 4 bilhões de anos atrás, e como a superfície do planeta foi remodelada e os oceanos formados.
1) The document provides a summary of a course on high-energy astrophysics that the author took. It discusses various topics covered in the course including accretion disks, pulsars, black holes, supernovae, and more.
2) The author argues that high-energy astrophysics is important for understanding the universe and requests that the provost offer a similar course at their university.
3) Key concepts in high-energy astrophysics discussed include accretion and its relation to luminosity, binary star systems, properties of neutron stars and black holes, and x-ray emissions from astrophysical phenomena like supernovae.
The most luminous_galaxies_discovered_by_wiseSérgio Sacani
This document presents a sample of 20 extremely luminous galaxies discovered by the Wide-field Infrared Survey Explorer (WISE). Five of these galaxies have infrared luminosities exceeding 1014 solar luminosities, the highest infrared luminosity threshold yet observed. They were selected using criteria requiring weak or no detection in the first two WISE bands but strong detections in the third and fourth bands. Spectral energy distribution modeling suggests their high luminosities are powered by obscured active galactic nuclei with hot dust temperatures around 450 Kelvin. The existence of such luminous galaxies at redshifts above 3 provides constraints on the early growth of supermassive black holes through rapid accretion.
Predictions of the_atmospheric_composition_of_gj_1132_bSérgio Sacani
GJ 1132 b is a nearby Earth-sized exoplanet transiting an M dwarf, and is amongst the most highly
characterizable small exoplanets currently known. In this paper we study the interaction of a magma
ocean with a water-rich atmosphere on GJ 1132b and determine that it must have begun with more
than 5 wt% initial water in order to still retain a water-based atmosphere. We also determine the
amount of O2
that can build up in the atmosphere as a result of hydrogen dissociation and loss.
We find that the magma ocean absorbs at most ∼ 10% of the O2 produced, whereas more than
90% is lost to space through hydrodynamic drag. The most common outcome for GJ 1132 b from our
simulations is a tenuous atmosphere dominated by O2
, although for very large initial water abundances
atmospheres with several thousands of bars of O2
are possible. A substantial steam envelope would
indicate either the existence of an earlier H2
envelope or low XUV flux over the system’s lifetime. A
steam atmosphere would also imply the continued existence of a magma ocean on GJ 1132 b. Further
modeling is needed to study the evolution of CO2
or N2
-rich atmospheres on GJ 1132 b.
This document presents evidence that massive galaxies at redshift 2.2 (~3 billion years after the Big Bang) undergo an "inside-out quenching" process, where star formation is quenched first in the inner regions and later in the outer disks. High-resolution observations of 22 star-forming galaxies show that the most massive galaxies already have dense bulges similar to local spheroids, while still actively forming stars in their outer disks. The data suggests star formation is suppressed from the inside out on timescales of less than 1 Gyr in the centers and up to a few Gyr in the outer disks, as an "inside-out quenching wave" propagates through the galaxies. This provides insights into how
First Observation of the Earth’s Permanent FreeOscillation s on Ocean Bottom ...Sérgio Sacani
The Earth’s hum is the permanent free oscillations of the Earth recorded in the absence ofearthquakes, at periods above 30 s. We present the first observations of its fundamental spheroidaleigenmodes on broadband ocean bottom seismometers (OBSs) in the Indian Ocean. At the ocean bottom,the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In ourexperiment, data are also affected by electronic glitches. We remove these signals from the seismic traceby subtracting average glitch signals; performing a linear regression; and using frequency-dependentresponse functions between pressure, horizontal, and vertical seismic components. This reduces the longperiod noise on the OBS to the level of a good land station. Finally, by windowing the autocorrelation toinclude only the direct arrival, the first and second orbits around the Earth, and by calculating its Fouriertransform, we clearly observe the eigenmodes at the ocean bottom.
This document summarizes evidence that argues against the hypothesis of a "lunar terminal cataclysm" approximately 3.9 billion years ago. It analyzes dating of lunar highland rocks and meteorites, finding they do not show a prominent peak at 3.9 billion years as expected, but rather a more uniform distribution of ages. Analysis of the cratering record of lunar basins also argues against a spike in the lunar bombardment rate at that time. Modeling of impact melt production and redistribution across the lunar surface further casts doubt on there having been a major cataclysm 3.9 billion years ago as hypothesized.
Evidence for Long-Lasting Electrical Leader Discharges in NonSpecular Meteor ...researchinventy
Unusual, non-specular, fast-movingmeteortrail echoes are observed in the summer polar upper mesosphere near 90 km.Usually, at mid-latitudes, field-aligned irregularities cause non-specular trails, while in the polar region long-lasting irregularities are possibly sustained by charged meteor dust.The unusual meteor trails propagate downward and upward at speeds of 3.3-6.4 kms-1 along a slanted path length of 10.4 km between 87-93 km altitudes, merging in the middle and lasting for 8-10s. Here we propose that an electrical discharge is responsible for these trails. The corresponding horizontal electric field for the observed speeds is estimated up to 16.3 Vm-1 at 90 km.Both the long-lasting merging of two fast-moving plasma trails and the modest speed compared to those (~104 -105 ms -1 ) of lightning leader process and of jets (< 400 ms) occurring above thunderclouds likely suggest a new type of meteor-trail leader discharge occurring in the summer polar upper mesosphere
The habitability of Proxima Centauri b - I. Irradiation, rotation and volatil...Sérgio Sacani
Proxima b is a planet with a minimum mass of 1.3 M⊕ orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass,
active star and the Sun’s closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b
and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet
and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time
evolution of the star’s spectrum, which is essential for modeling the flux received over Proxima b’s lifetime. We also show that Proxima
b’s obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet’s eccentricity and
level of triaxiality. Next we consider the evolution of Proxima b’s water inventory. We use our spectral energy distribution to compute
the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find
that Proxima b is likely to have lost less than an Earth ocean’s worth of hydrogen (EOH) before it reached the HZ 100–200 Myr after
its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We
conclude that Proxima b is a viable candidate habitable planet.
Similar to Different Martian Crustal Seismic Velocities across the Dichotomy Boundary from Multi-Orbiting Surface Waves (20)
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
Cytokines and their role in immune regulation.pptx
Different Martian Crustal Seismic Velocities across the Dichotomy Boundary from Multi-Orbiting Surface Waves
1. Different Martian Crustal Seismic Velocities across the Dichotomy
Boundary from Multi-Orbiting Surface Waves
Jiaqi Li1*
, Caroline Beghein1
, Philippe Lognonné2
, Scott M. McLennan3
, Mark Wieczorek4
, Mark Panning5
, Brigitte
Knapmeyer-Endrun6
, Paul Davis1
, and William Bruce Banerdt5
1
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA.
E-mail: jli@epss.ucla.edu
2
Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, F-75005, France.
3
Department of Geosciences, Stony Brook University, Stony Brook, New York, 11794–2100 USA.
4
Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France.
5
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
6
Bensberg Observatory, University of Cologne, 51429 Bergisch Gladbach, Germany.
Accepted
Article
This article has been accepted for publication and undergone full peer review but has not been through
the copyediting, typesetting, pagination and proofreading process, which may lead to differences between
this version and the Version of Record. Please cite this article as doi: 10.1029/2022GL101243.
This article is protected by copyright. All rights reserved.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
2. Accepted
Article
This article is protected by copyright. All rights reserved.
Abstract
We have observed both minor-arc (R1) and major-arc (R2) Rayleigh waves for the largest marsquake (magnitude
of 4.7 ± 0.2) ever recorded. Along the R1 path (in the lowlands), inversion results show that a simple, two-layer
model with an interface located at 21 - 29 km and an upper crustal shear-wave velocity of 3.05 - 3.17 km/s can fit the
group velocity measurements. Along the R2 path, observations can be explained by upper crustal thickness models
constrained from gravity data and upper crustal shear-wave velocities of 2.61 - 3.27 km/s and 3.28 - 3.52 km/s in the
lowlands and highlands, respectively. The shear-wave velocity being faster in the highlands than in the lowlands
indicates the possible existence of sedimentary rocks, and relatively higher porosity in the lowlands.
Plain Language Summary
The largest marsquake ever recorded occurred recently and waves propagating at the surface, called surface waves,
have been observed. Owing to the relatively large magnitude (i.e., 4.7 ± 0.2) of this event, surface wave energy is
still clearly visible after one orbit around the red planet. The shortest path taken by the wave propagating between
the source and the receiver is located in the northern lowlands, near the boundary with the southern highlands (called
dichotomy). The surface wave traveling in the opposite direction, following the longer distance between the quake
and the seismic station, mostly passes through the highlands. Analyses of these two paths reveal that the average
shear-wave velocity is faster in the highlands than in the lowlands near the dichotomy boundary. This lower velocity
in the lowlands may be due to the presence of thick accumulations of sedimentary rocks and relatively higher porosity.
Key Points:
⚫ Analyses of the minor-arc and major-arc Rayleigh waves reveal different Martian crustal structures across the
dichotomy boundary
⚫ The average shear-wave velocity is faster in the highlands than in the lowlands near the dichotomy boundary.
⚫ The lower shear-wave velocity in the lowlands may be due to the presence of sedimentary rocks and relatively
higher porosity.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
3. Accepted
Article
This article is protected by copyright. All rights reserved.
1. Introduction
The InSight (Banerdt et al., 2020) mission landed a very broadband seismometer (Lognonné et al., 2019), on Mars
in Nov 2018 to better understand the structure, evolution, and differentiation of the Martian crust. In nearly three and
a half years, more than one thousand marsquakes and several impact events have been recorded (Clinton et al., 2021;
Garcia et al., 2022; Posiolova et al., 2022). So far, multiple body-wave signals have been clearly recorded (Clinton
et al., 2021), but observable surface-wave signals were only recently reported for two impact events (Kim et al.,
2022).
Due to the lack of surface wave observations, previous seismological studies of the Martian crust and the topmost
mantle were mainly based on body waves and ambient noise correlations (e.g., Lognonné et al., 2020; Knapmeyer-
Endrun et al., 2021; Compaire et al., 2021; Schimmel et al., 2021; Li et al, 2022a and 2022b). Since the ray paths of
the above-mentioned signals are nearly vertically incident beneath the seismometer, most of the sampled sub-surface
structures are limited to the vicinity of the InSight landing site (i.e., within a radius of ~ 50 km). Nevertheless, there
were attempts to constrain the crustal structures at other locations (e.g., Li et al., 2022c).
On the 1222nd Martian day (sol) of the InSight mission, the largest marsquake (S1222a) ever recorded occurred
with a magnitude of 4.7 ± 0.2, which corresponds to energy five times greater than the second-largest event
(Kawamura et al. 2022; InSight Marsquake Service, 2022). For the first time, both Rayleigh and Love waves were
observed on a planet other than Earth (Kawamura et al. 2022; Beghein et al. 2022; Xu et al., 2022).
On a radially stratified, laterally homogeneous sphere, a surface wave travels along the great-circle path. The wave
that travels along the shorter path between the source and the receiver is named the minor-arc Rayleigh wave (R1).
The wave that travels in the other direction, along the longer path, is named the major-arc Rayleigh wave (R2). The
Rayleigh wave arrival is called R3 when the minor-arc wave circuits the globe and eventually reaches the station
again. On Earth, R2 and R3 can fill the gap of poorly covered areas in tomographic models (constrained by R1 alone)
and thus enhance the resolution (e.g., Trampert and Woodhouse, 1996). On Mars, the R2 and R3 observations are
very important since there is only one station and thus there are lots of gaps to cover.
To observe the R2 and R3 Rayleigh waves, which are of much smaller amplitude than R1, the minimum moment
magnitude was estimated to be Mw 6.0 for quiet stations on Earth (Panning et al., 2015). On Mars, the minimum
requirement for marsquakes is between Mw 4.6 and Mw 5.3, mainly due to Mars’s smaller radius (Panning et al.,
2015). As predicted, the large magnitude of event S1222a enabled observations of R2 and R3 on Mars (Panning et
al., 2022).
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
4. Accepted
Article
This article is protected by copyright. All rights reserved.
The epicentral distance of event S1222a is 37.0 ± 1.6 degrees, and the back azimuth is estimated to be between 96
and 112 degrees (Kawamura et al. 2022), placing the location of S1222a in the lowlands and near the dichotomy
boundary. The dichotomy boundary separates the northern lowlands and southern highlands and has highly debated
origins (Zhong and Zuber, 2001; Marinova et al., 2008; Andrews-Hanna et al., 2008; Frey, 2006). The R2 and R3
Rayleigh waves pass through both the lowlands and the highlands (Fig. 1), which are far from the InSight lander and
were scarcely sampled by seismic waves with the previously recorded marsquakes. These observations allow us to
put new constraints on the crustal structure away from the lander in both the lowlands and the highlands.
In this paper, we first measured the group velocity of the Rayleigh waves along the R1, R2, and R3 paths. Then,
we performed inversions for R1 and R2 (the R3 measurements are less reliable, as explained below) to derive seismic
velocity models that could explain the observations. After comparing the seismic velocity profiles in the lowlands
and highlands, we discuss the possible effects of the crustal variations on the observed group velocities of the minor-
and major-arc Rayleigh waves.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
5. Accepted
Article
This article is protected by copyright. All rights reserved.
Figure 1.
(a) MOLA (Mars Orbiter Laser Altimeter, Smith et al., 2001) map. The red star marks the optimal hypocenter of
event S1222a (Kawamura et al., 2022), and the black triangle indicates the broadband seismometer of the InSight
mission. The red and blue curves denote the great-circle paths of R1 and R2, respectively. The shaded grey areas
illustrate all possible paths for R1 and R2 based on the back azimuth uncertainty of the event location (Kawamura
et al., 2022).
(b) Elevation variations along the Rayleigh wave paths shown in (a). Regions within 10 degrees of the optimal great-
circle path are displayed to account for the finite frequency effect (e.g., Zhou et al., 2004).
(c) Lateral variations of the upper crust along the Rayleigh wave great-circle path in (a). The depth of the interface
at the InSight lander site is fixed at 26 km from the R1 inversion (in Fig. 3c), and the relative variations are
constrained by gravity data (Wieczorek et al., 2022). The location of the dichotomy boundary is from Tanaka et
al. (2014).
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
6. Accepted
Article
This article is protected by copyright. All rights reserved.
2. Data
The minor arc Rayleigh wave, which travels 2,193 ± 95 km (using an equatorial radius of 3396.2 km), arrives
around 800 s after the origin time on the vertical component of the seismogram and can be observed over a relatively
broad frequency band on both the vertical (i.e., 10 to 60 s, in Fig. 2a) and the radial components (Fig. S1). Since the
seismometer is in an extremely harsh environment, the diurnal temperature variations could generate one-sided pulses
(hereafter referred to as glitches) that can contaminate the seismic signals. A comparison between the raw data and
the deglitched data (Scholz et al., 2020) shows that there is no significant glitch near the R1 arrival time (Fig. S1).
R2 travels a much longer distance of about 19,146 ∓ 95 km and arrives around 6,650 s after the origin time (Fig.
2b). R2 is observed within a relatively narrow frequency range (i.e., 25 to 35 s), and the amplitude is only about one-
fourth of that of R1. Although there is no glitch near the R2 arrival, another signal of a slightly smaller amplitude
occurs at about 6,800 to 7,000 s. Panning et al. (2022) excluded this signal as being the R2 phase since this later
arrival does not show strong and consistent elliptical particle motions at different frequency bands (which is expected
for the Rayleigh wave), and the corresponding marsquake location would be highly inconsistent with the one
constrained by body waves (Kawamura et al. 2022). Therefore, we prefer selecting the R2 signal at around 6,650 s.
The R3 wave, which travels 23,532 ± 95 km, overlaps with a glitch in the raw data (Fig. 2b). R3 is still visible on
the deglitched data and exhibits arrival times of about 8,100 s. However, since the deglitching procedure may not
perfectly fit the real glitch and thus could also remove some seismic signals, the R3 signals (e.g., the arrival time and
amplitude) are less reliable than R1 or R2. Therefore, in the following analysis, we mainly focus on R1 and R2 and
consider R3 as auxiliary data for benchmarking purposes.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
7. Accepted
Article
This article is protected by copyright. All rights reserved.
Figure 2.
(a) Seismic waveforms (after removing the instrument response and bandpass filter from 10 to 60 s) on the vertical
component near the arrival times of the S wave and R1. The black and red waveforms are the velocity records
from the raw dataset and deglitched dataset, respectively. The shaded gray region marks the time window in
which we performed the multiple filter analysis in (c).
(b) Waveforms on the vertical component near the arrivals of R2 and R3 with a filter band of 25 to 35 s.
(c) Multiple filter analysis (Herrmann, 2013) for R1 on the vertical component. The x- and y-axes are the period and
group velocity, respectively. Color scales represent the energy contours (in dB) of the waveform envelope. The
black circles indicate the preferred group velocity measurements. The vertical grey error bar spans 1 dB. Note
that at periods greater than 32 s, the R1 measurements show discrepancies between the vertical and radial
components (see Fig. S2) and thus are less reliable (denoted by the dashed error bars).
(d) Similar to (c) but for R2 on the vertical component.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
8. Accepted
Article
This article is protected by copyright. All rights reserved.
3. Method and Results
3.1 Group Velocity Measurements
To measure the Rayleigh wave group velocity, we first performed a multiple filter analysis (Herrmann, 2013) to
calculate the energy of the waveform envelope at different periods (Fig. 2c and d). Then, we selected the optimal
group velocity at each period corresponding to the maximum energy (in dB) of the waveform envelope. Finally, we
defined the uncertainty of the measurements using a 1dB threshold (Beghein et al., 2010), i.e., group velocities with
amplitudes within 1dB of the maximum amplitude are viewed as acceptable measurements.
The reliable period range for the R1 signal on the vertical component is from 17 s to 32 s, where the group velocities
are consistent with those measured on the radial component (Fig. S2). For the average group velocity along the R1
path, there are clear signs of positive dispersion, i.e., the group velocity increases with the period. Given the origin
time of 2022-05-04 23:23:06.5 (UTC) and the epicentral distance of 37 degrees (Kawamura et al. 2022), the R1 group
velocity increases from 2.70 ± 0.05 km/s at 17 s to 2.95 ± 0.05 km/s at 41 s (Fig. 2c, see Text S1 for discussions on
the location error).
We applied the same analysis to the R2 signal and found that it exhibits little dispersion between periods of 23 s
and 39 s, with a nearly constant group velocity of 2.90 km/s ± 0.01 km/s (Fig. 2d). It is worth mentioning that the
uncertainty of the R2 group velocity is much smaller (less than one-fifth) than that of R1 due to its longer travel time
(See Text S1 for details).
Fig. 2b shows that R3 is significantly affected by a glitch. Nevertheless, based on the deglitched data, the multiple
filter analysis shows little dispersion and a nearly constant group velocity of about 2.90 km/s ± 0.02 km/s (Fig. S3).
This similar value of the R2 and R3 group velocities confirms the reliability of the R2 measurements given their
similar paths (i.e., they share the same path for about 19,000 km or about 80% of the R3 path length).
3.2 Inversion Along the R1 Path
We inverted the group velocity measurements to constrain the average seismic velocity profile along the R1 path
using a Niche Genetic Algorithm (Koper et al., 1999; Li et al., 2021) to sample different possible models and the CPS
code package (Herrmann, 2013) to calculate the group velocities predicted by these models at different periods.
We chose to represent the model with a layered crustal parameterization because previous receiver function studies
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
9. Accepted
Article
This article is protected by copyright. All rights reserved.
(Lognonné et al., 2020; Kim et al., 2021; Knapmeyer-Endrun et al., 2021) exhibited the presence of sharp interfaces
in the crust. In addition, we preferred to set the number of layers to two because this model setting with only three
free parameters (i.e., the depth of the interface, and the shear-wave velocities above and below this interface) is less
likely prone to overfitting the data. If this simplified model fails to fit the observed group velocities, we can then
consider a more complex model. Based on the sensitivity curves of the Rayleigh waves at periods shorter than 40 s
(Fig. S4), we only constrained the structure above 80 km depth. At greater depths, we used the values of the
InSight_KKS21GP model (Knapmeyer-Endrun et al., 2021; Khan et al., 2021; Stähler et al., 2021a and 2021b), which
was constructed from teleseismic body waves (See Text S2 for the model setup). We also tested a smoothed model
setting with eight third-order B-splines (Fig. 3d) and found that the average velocities above (or below) the interface
are similar between the discontinuity and the smoothed model settings (Fig. S5).
Fig. 3c shows that a simplified model with two layers in the top 80 km can reproduce the R1 dispersion curve.
Specifically, the shear-wave velocity is estimated to be 3.05 - 3.17 km/s in the top layer, and 3.50 - 3.78 km/s in the
bottom layer. The interface depth estimation is 21 - 29 km. Fig. 3f shows that the depth of the inverted interface along
the R1 path overlaps with the depth of the intra-crustal interface beneath the InSight lander constrained by the receiver
function (Knapmeyer-Endrun et al., 2021), although the mean value deviates (possibly due to the difference in the
regions to which those two methods are sensitive).
We note that Knapmeyer-Endrun et al. (2021) provided two possible crustal thicknesses beneath the lander: a
thinner crustal model with a shallow Moho depth of 20 ± 5 km, and a thicker crustal model (where the interface at
around 20 km is interpreted as an intra-crustal interface) with a deeper Moho depth of 39 ± 8 km (though with a
smaller impedance contrast across this deeper Moho). Here, we prefer to refer to the interface at 21- 29 km (inverted
in this study) as the intra-crustal interface since subsequent studies from Kim et al. (2021) and Durán et al. (2022)
favored the thicker crustal scenario. We also want to note that we cannot resolve the deeper Moho (if it exists) since
only the discontinuity with the most significant velocity jump will be detected with the current one-interface setting.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
10. Accepted
Article
This article is protected by copyright. All rights reserved.
Figure 3.
(a) Group velocity measurements (grey circles), uncertainties (vertical bars), and synthetic group velocity dispersion
curves (in red, corresponding to the models shown in (c) with the same color) along the R1 path. The range of
the y-axis (i.e., group velocity) in the shaded gray region is the same as that in (b).
(b) Similar to (a), but for the R2 path, and the corresponding models (in blue) shown in (c).
(c) Shear-wave velocity profiles for all the acceptable models along the R1 (in red) and R2 (in blue) paths from the
inversion for the discontinuity model setting.
(d) Similar to (c), but for the smoothed (i.e., third-order B-splines) model setting.
(e) Normalized probability density functions of the shear-wave velocities in the upper crust for all the acceptable
models (R1 models in red, and R2 models in blue) in (c).
(f) Similar to (e), but for the shear-wave velocities in the lower crust and mantle (i.e., down to 80 km).
(g) Similar to (e), but for the depth of the crustal interface. The probability density function in gray shows the depth
of the base of the intra-crustal discontinuity beneath the lander from the receiver function study (Knapmeyer-
Endrun et al., 2021).
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
11. Accepted
Article
This article is protected by copyright. All rights reserved.
3.3 Inversion Along the R2 Path
We note that it is reasonable to perform the inversion with a representative one-layer model along the entirety of
the R1 path since there are few topographic changes (e.g., Fig. 4a). However, along the R2 path, it may be preferable
to account for the significant lateral variations in both topography and crustal thickness (Wieczorek et al., 2022),
rather than simply using an average one-layer model (e.g., Fig. 3c) to explain the R2 dispersion curve in Fig. 3b.
We thus divided the R2 path into 3,230 sub-paths, and within each sub-path (of which the length is shorter than
the wavelength) we can assume a one-layer model with a similar setup as for R1. The upper crustal thickness models
along the R2 path are modified from Wieczorek et al. (2022) as prior information (See Text S3 for the R2 model
setup). There are only three free parameters in the R2 inversion, i.e., the upper crustal shear-wave velocities in the
lowlands (𝑉𝐿) and highlands (𝑉𝐻), and the shear-wave velocity below the crustal interface (𝑉2).
Grid search results show that within the given range of 𝑉2 (i.e., 3.50 - 3.78 km/s from the R1 inversion results in
Fig. 3e), a series of models (Fig. 4b), with upper crustal velocities of 2.61 - 3.27 km/s in the lowlands and 3.28 - 3.52
km/s in the highlands, can fit the R2 measurements (Fig. S6).
The probability density functions in Fig. 4c illustrate that the upper crustal shear-wave velocity in the highlands
(i.e., 3.28 - 3.52 km/s) is systematically faster than that in the lowlands (i.e., 2.61 - 3.27 km/s). We further reduced
the number of acceptable models from the R2 inversion with the extra constraint from the R1 inversion (i.e., upper
crustal velocity in the lowlands should be in the range of 3.05 - 3.17 km/s). The down-selected models, which satisfy
both the R1 and R2 observations, also demonstrate a greater upper crustal shear-wave velocity in the highlands (i.e.,
3.17 - 3.33 km/s) than that in the lowlands (i.e., 3.05 - 3.17 km/s).
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
12. Accepted
Article
This article is protected by copyright. All rights reserved.
Figure 4.
(a) Model setup for the R2 inversion. The upper crustal thickness models modified from Wieczorek et al. (2022) are
used as prior information and fixed in the inversion. Along the R2 path, the only three free parameters are the
upper crustal shear-wave velocities in the lowlands (𝑉𝐿) and highlands (𝑉𝐻), and the shear-wave velocity (𝑉2)
below the crustal interface (See Text S3 for the R2 model setup).
(b) Grid search results for the upper crustal shear-wave velocity in the lowlands (𝑉𝐿, the y-axis), and the upper
crustal shear-wave velocity in the highlands (𝑉𝐻, the x-axis) along the R2 path. The acceptable models that can
fit the R2 measurements are shown as filled circles, with color scales corresponding to the misfits (See Text S2
for the misfit function). The dashed region indicates where the models also satisfy the R1 observations (i.e., an
upper crustal shear-wave velocity of 3.05 - 3.17 km/s in the lowlands). The shaded gray area to the left of the
diagonal indicates the region where the upper crustal velocity in the lowlands is faster than that in the highlands.
Note that at each gird point, a grid search for the shear-wave velocity below the crustal interface (𝑉2) is also
performed.
(c) Normalized probability functions of the upper crustal shear-wave velocities (lowlands models are in red, and
highlands models are in blue) for the acceptable models in (b). S-wave velocities beneath the InSight lander (in
the depth range of ~ 8 - 20 km, Knapmeyer-Endrun et al., 2021) and along the great circle path from the meteorite
impact S1094b (Kim et al., 2022) are also annotated.
(d) Similar to (c), but for the models that satisfy both the R1 and R2 observations (i.e., in the dashed region in (b)).
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
13. Accepted
Article
This article is protected by copyright. All rights reserved.
4. Discussion
4.1 Comparison with the InSight landing site
The most sensitive depth range of the Rayleigh waves analyzed is from ~ 10 to 50 km (Fig. S7), though there are
also a few sensitivities to greater depths. Therefore, we have better constraints on the upper crust (i.e., above the
crustal interface), than the lower crust and mantle.
Since Lognonné et al. (2020) and Knapmeyer-Endrun et al. (2021) obtained the first Martian crustal structure
beneath the InSight landing site, whether it represents local geologies or global features has been debated. In the
similar depth range of ~ 8 - 20 km, beneath the lander, the S-wave velocity is estimated to be 2.2 ± 0.6 km/s
(Knapmeyer-Endrun et al., 2021). This upper crustal velocity beneath the lander (also located in the lowlands) is
significantly smaller than the average velocity (i.e., ~ 3 km/s, see Fig. 4c and d) along the surface wave path in the
lowlands.
Similar S-wave velocity (i.e., ~ 3.2 km/s) of the upper crust in the lowlands (along the surface wave path from a
meteorite impact) has also been recently reported (Kim et al., 2022). This faster velocity has been attributed to the
different compositions and/or reduced porosity in the volcanic areas along the path (Kim et al., 2022).
For marsquake S1222a, the surface wave path also likely traverses the volcanic units in the lowlands (Fig. S8).
Therefore, the crustal porosity may have been occluded or obscured by later magmatism (e.g., Wilson and Head,
1994), resulting in a faster S-wave velocity than beneath the lander (where there are higher porosities).
4.2 Upper Crust in the Lowlands and the Highlands
The upper crust velocity in the lowlands, though larger than the InSight landing site, is systematically smaller than
that in the highlands (Fig. 4c and d). Possible interpretations for the smaller upper crustal shear-wave velocity values
in the lowlands than in the highlands could include some combination of differing compositions, reductions in
porosity at depth, and/or the presence of sedimentary rocks.
Variations in lithology and rock compositions are a common major cause of regional variations in crustal seismic
structure (Rudnick and Fountain, 1995). The Martian crust is thought to be of basaltic composition on average (Taylor
and McLennan, 2009). Recently, using global crustal thickness and thermal evolution models, Thiriet et al. (2018)
suggested that felsic rocks were more common in the Noachian-dominated southern highlands, leading to an average
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
14. Accepted
Article
This article is protected by copyright. All rights reserved.
bulk density of 480 kg/m3
less than the northern lowland crust. However, this density difference should lead to lower,
rather than higher, seismic velocities (for a wide range of lithologies, e.g., Brocher, 2005) in the highlands.
Compositional differences could also affect the thermal regime and thus have an indirect influence on seismic
velocities. For example, a more differentiated southern highland crust would also be characterized by higher
abundances of heat-producing elements (Thiriet et al., 2018; Wieczorek et al., 2022) and, when coupled with a thicker
crust, higher heat flow (e.g., Hahn et al., 2011; Parro et al., 2017). A distinctive crustal thermal regime could lead to
very different depth-dependent porosity behavior.
Porosity can also significantly affect the seismic wave speed such that higher porosity results in lower shear-wave
velocity (e.g., Manga and Wright 2021). Both compaction and viscous deformation will result in porosity reduction
with depth. Gyalay et al. (2020) showed that the closure of pore space should occur over a narrow depth range of a
few kilometers and all porosity should have been removed for depths greater than about 12-23 km (Wieczorek et al.
2022). Accordingly, in the highlands, where the upper crust is thicker on average (Fig. 4a) and surface heat flow is
greater (Hahn et al., 2011; Parro et al., 2017), a larger proportion of the upper crust may lie beneath depths where
porosity has been lost, leading to shear-wave velocities that are higher than in the northern lowlands when averaged
over the thickness of the upper crust interrogated by the R2 paths.
To quantitatively assess the influence of porosity, we assumed that the velocity difference between the lowlands
and highlands is affected by porosity alone. With a pore closure depth of 23 km (Wieczorek et al. 2022) and an aspect
ratio of 0.1 (Heap, 2019), the velocity difference can be explained by a porosity reduction of 8 - 15% (Fig. S9, see
Text S4 for details).
The presence of thick accumulations of sedimentary rocks could also lead to lower density (and thus, for a wide
range of lithologies, low shear-wave velocities, e.g., Brocher, 2005) due to a variety of features/processes, including
the presence of elevated primary porosity for poorly consolidated and/or weakly cemented sedimentary rocks;
secondary porosity for diagenetically altered sedimentary rocks; low-density hydrated alteration phases, such as
phyllosilicates and amorphous silica, formed during chemical weathering and/or diagenesis (McLennan & Grotzinger,
2008; McLennan et al., 2019). However, for most locations on Mars, sedimentary rock thicknesses are on the order
of a few kilometers at most (e.g., Grotzinger et al., 2015; Grotzinger and Milliken, 2012; Bradley et al., 2002).
Therefore, based on our current knowledge of the total sedimentary mass and its distribution on Mars (e.g., McLennan,
2012, Grotzinger and Milliken, 2012), the presence of sedimentary rocks alone probably cannot explain the lower
upper crustal shear-wave velocity in the lowlands, where the crustal interface is located at ~ 26 km.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
15. Accepted
Article
This article is protected by copyright. All rights reserved.
4.3 R2 Group Velocity
Another major difference between the group velocity along R1 and R2 is that there is positive dispersion along R1
but there is almost no dispersion along R2. We found that for a typical velocity model derived for the highlands,
where the upper crustal thickness is greater than in the lowlands, the group velocity exhibits negative dispersion.
Therefore, the negative dispersion in the highlands (Fig. S7e) could cancel out the positive dispersion in the lowlands
(Fig. S7d), yielding little dispersion along the R2 path.
However, it is worth noting that long-period pressure-induced signals are also present in seismic data (Kenda et
al., 2020; Stutzmann et al., 2021) and are carried by the environmental wind, resulting in an apparent burst of noise
without dispersion. Given the relatively low signal-to-noise ratio for R2 and R3, this absence of dispersion could also
be an artifact of the wind noise.
5. Conclusion
We have observed two minor-arcs (R1, and R3) and one major-arc (R2) Rayleigh wave generated by the largest
marsquake ever recorded. The group velocities along the R1 path increase from 2.70 ± 0.05 km/s to 2.95 ± 0.05 km/s
between periods of 17 s and 42 s and can be explained by a two-layer model with a crustal interface depth of 21 - 29
km and an upper crustal shear-wave velocity of 3.05 - 3.17 km/s in the lowlands. The group velocity along the R2
path exhibits a nearly constant value of 2.90 km/s and can be explained by upper crustal thickness models constrained
from gravity data and upper crustal shear-wave velocities of 2.61 - 3.27 km/s and 3.28 - 3.52 km/s in the lowlands
and highlands, respectively. The lower shear-wave velocity in the lowlands compared to that in the highlands may be
due to the presence of thick accumulations of sedimentary rocks, and relatively higher porosity.
Acknowledgments
J.L. and C.B. were supported by NASA InSight PSP grant #80NSSC18K1679 and S. M. McLennan by NASA
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
16. Accepted
Article
This article is protected by copyright. All rights reserved.
InSight PSP grant #80NSSC18K1622. P.L. and M.W. are supported by Agence Nationale de la Recherche (MAGIS,
ANR-19-CE31-0008-08; IdEx Université Paris Cité, ANR-18-IDEX-0001) and by CNES for SEIS science support.
This is InSight Contribution Number 278. InSight seismic data presented here
(http://dx.doi.org/10.18715/SEIS.INSIGHT.XB_2016) are publicly available through the Planetary Data System
(PDS) Geosciences node (InSight SEIS Data Bundle, 2021), the Incorporated Research Institutions for Seismology
(IRIS) Data Management Center under network code XB and through the Data center of Institut de Physique du
Globe, Paris. We acknowledge NASA, CNES, their partner agencies and Institutions (UKSA, SSO, DLR, JPL, IPGP-
CNRS, ETHZ, IC, MPS-MPG), and the flight operations team at JPL, SISMOC, MSDS, IRIS-DMC, and PDS for
providing SEED SEIS data.
Conflict of Interest
The authors declare no conflicts of interest relevant to this study.
Open Research
The datasets used in this study are achieved and released by InSight Mars SEIS Data Service and are
available to the science community (InSight Mars SEIS Data Service, 2019; InSight Marsquake Service,
2022). Data sets (both the raw data and the deglitched data in SAC format, after removing the instrument
response) for this research are available on the Zenodo repository: https://doi.org/10.5281/zenodo.7325555.
The InSight_KKS21GP model is available on the IPGP Data Center (doi: 10.18715/IPGP.2021.kpmqrnz8).
References
Andrews-Hanna, J.C., Zuber, M.T. and Banerdt, W.B., 2008. The Borealis basin and the origin of
the Martian crustal dichotomy. Nature, 453(7199), pp.1212-1215.
Banerdt, W.B., Smrekar, S.E., Banfield, D., Giardini, D., Golombek, M., Johnson, C.L., Lognonné,
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
17. Accepted
Article
This article is protected by copyright. All rights reserved.
P., Spiga, A., Spohn, T., Perrin, C. and Stähler, S.C., 2020. Initial results from the InSight mission
on Mars. Nature Geoscience, 13(3), pp.183-189.
Beghein et al., 2022. Evidence for Large-Scale Seismic Anisotropy in the Martian Crust from
Surface Waves (submitted to the GRL S1222a special issue).
Bradley, B. A., Sakimoto, S. E., Frey, H., Zimbelman, J. R., 2002. Medusae Fossae Formation:
New perspectives from Mars Global Surveyor. Journal of Geophysical Research – Planets, 107,
E85050, doi:10.1029/2001JE001537.
Brocher, T. M. (2005) Empirical relations between elastic wavespeeds and density in the Earth's
crust. Bull. Seis. Soc. Amer., 95, 2081-2092.
Clinton, J. F., Ceylan, S., van Driel, M., Giardini, D., Stähler, S. C., Böse, M., Charalambous, C.,
Dahmen, N. L., Horleston, A., Kawamura, T., et al., 2021. The marsquake catalogue from
InSight, sols 0–478, Physics of the Earth and Planetary Interiors, 310, 106595.
Compaire, N., Margerin, L., Garcia, R. F., Pinot, B., Calvet, M., Orhand-
Mainsant, G., Kim, D., Lekic, V., Tauzin, B., Schimmel, M., et al., 2021. Autocorrelation of
the ground vibrations recorded by the seis-insight seismometer on mars, Journal of Geophysical
Research: Planets, 126(4), e2020JE006498.
Durán, C., A. Khan, S. Ceylan, G. Zenhäusern, S. Stähler, J. F. Clinton, and D. Giardini.
"Seismology on Mars: An analysis of direct, reflected, and converted seismic body waves with
implications for interior structure." Physics of the Earth and Planetary Interiors 325 (2022): 106851.
Frey, H.V., 2006. Impact constraints on the age and origin of the lowlands of Mars. Geophysical
Research Letters, 33(8).
Garcia, Raphael F., et al. "Newly formed craters on Mars located using seismic and acoustic
wave data from InSight." Nature Geoscience (2022): 1-7.
Grotzinger, J. P., Gupta, S., Malin, M. C., Rubin, D. M., Schieber, J. et al. (2015) Deposition,
exhumation, and paleoclimate of an ancient lake deposit, Gale Crater, Mars. Science, 350,
aac7575, doi:10.1126/science.aac7575.
Grotzinger, J. P., Milliken, R. E., 2012. The sedimentary rock record of Mars: Distribution,
origins, and global stratigraphy. In: J. P. Grotzinger and R. E. Milliken (eds.) Mars
Sedimentology, SEPM Spec. Publ. 102, 1-48.
Gyalay, S., Nimmo, F., Plesa, A.-C., Wieczorek, M., 2020. Constraints on thermal history of
Mars from depth of pore closure below InSight. Geophysical Research Letters, 47,
e2020Gl088653.
Heap, M. J. (2019). P-and S-wave velocity of dry, water-saturated, and frozen basalt:
Implications for the interpretation of Martian seismic data. Icarus, 330, 11-15.
Herrmann, R.B., 2013. Computer programs in seismology: An evolving tool for instruction and
research. Seismological Research Letters, 84(6), pp.1081-1088.
InSight Mars SEIS Data Service. (2019). SEIS raw data, Insight Mission. IPGP, JPL, CNES, ETHZ,
ICL, MPS, ISAE-Supaero, LPG, MFSC. https://doi.org/10.18715/SEIS.INSIGHT.XB_2016
InSight Marsquake Service (2022). Mars Seismic Catalogue, InSight Mission; V12 2022-10-01.
ETHZ, IPGP, JPL, ICL, Univ. Bristol. https://doi.org/10.12686/a18
InSight SEIS Data Bundle. 2021. PDS Geosciences (GEO) Node.
Kawamura et al., 2022. Largest Marsquake Ever Detected by InSight: S1222a. (submitted to the
GRL S1222a special issue, attached).
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
18. Accepted
Article
This article is protected by copyright. All rights reserved.
Kenda, B., Drilleau, M., Garcia, R.F., Kawamura, T., Murdoch, N., Compaire, N., Lognonné, P.,
Spiga, A., Widmer‐Schnidrig, R., Delage, P. and Ansan, V., 2020. Subsurface structure at the
InSight landing site from compliance measurements by seismic and meteorological experiments.
Journal of Geophysical Research: Planets, 125(6), p.e2020JE006387.
Khan, A., Ceylan, S., van Driel, M., Giardini, D., Lognonné, P., Samuel, H., Schmerr, N.C.,
Stähler, S.C., Duran, A.C., Huang, Q. and Kim, D., 2021. Upper mantle structure of Mars from
InSight seismic data. Science, 373(6553), pp.434-438.
Kim, D., Lekić, V., Irving, J.C., Schmerr, N., Knapmeyer‐Endrun, B., Joshi, R., Panning, M.P.,
Tauzin, B., Karakostas, F., Maguire, R. and Huang, Q., 2021. Improving constraints on planetary
interiors with PPS receiver functions. Journal of Geophysical Research: Planets, 126(11),
p.e2021JE006983.
Kim, D., Banerdt, W.B., Ceylan, S., Giardini, D., Lekić, V., Lognonné, P., Beghein, C., Beucler,
É., Carrasco, S., Charalambous, C. and Clinton, J., 2022. Surface waves and crustal structure on
Mars. Science, 378(6618), pp.417-421.
Knapmeyer-Endrun, B., Panning, M. P., Bissig, F., Joshi, R., Khan, A., Kim, D., Lekic, V.,
Tauzin, B., Tharimena, S., Plasman, M., et al., 2021. Thickness and structure of the martian crust
from InSight seismic data, Science, 373(6553), 438–443.
Koper, K.D., Wysession, M.E. and Wiens, D.A., 1999. Multimodal function optimization with a
niching genetic algorithm: A seismological example. Bulletin of the Seismological Society of
America, 89(4), pp.978-988.
Li, J., Beghein, C., Wookey, J., Davis, P., Lognonné, P., Schimmel, M., Stutzmann, E.,
Golombek, M., Montagner, J.P. and Banerdt, W.B., 2022a. Evidence for crustal seismic
anisotropy at the InSight lander site. Earth and Planetary Science Letters, 593, p.117654.
Li, J., Beghein, C., Davis, P., Wieczorek, M.A., McLennan, S.M., Kim, D., Lekić, V., Golombek,
M., Schimmel, M., Stutzmann, E. and Lognonné, P., 2022b. Crustal Structure Constraints from
the Detection of the SsPp Phase on Mars. Earth and Space Science, p.e2022EA002416.
Li et al., 2022c. Second Seismic Anchor Point of the Martian Crustal Structure Away From the
InSight Landing Site. Nature Communications (under review, 10.21203/rs.3.rs-1829147/v1).
Li, J., Beghein, C., et al., 2022d. Data for "Different Martian Crustal Seismic Velocities across
the Dichotomy Boundary from Multi-Orbiting Surface Waves". Zenodo.
https://doi.org/10.5281/zenodo.7325555
Li, J., Chen, M., Koper, K.D., Zhou, T., Xi, Z., Li, S. and Li, G., 2021. FastTrip: A Fast MPI‐
Accelerated 1D Triplication Waveform Inversion Package for Constraining Mantle Transition
Zone Discontinuities. Seismological Research Letters, 92(4), pp.2647-2656.
Lognonné, P., Banerdt, W.B., Giardini, D., Pike, W.T., Christensen, U., Laudet, P., De Raucourt,
S., Zweifel, P., Calcutt, S., Bierwirth, M. and Hurst, K.J., 2019. SEIS: Insight’s seismic
experiment for internal structure of Mars. Space Science Reviews, 215(1).
Lognonné, P., Banerdt, W., Pike, W., Giardini, D., Christensen, U., Garcia, R. F., Kawamura, T.,
Kedar, S., Knapmeyer-Endrun, B., Margerin, L., et al., 2020. Constraints on the shallow elastic and
anelastic structure of Mars from InSight seismic data, Nature Geoscience, 13(3), 213–220.
Marinova, M.M., Aharonson, O. and Asphaug, E., 2008. Mega-impact formation of the Mars
hemispheric dichotomy. Nature, 453(7199), pp.1216-1219.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
19. Accepted
Article
This article is protected by copyright. All rights reserved.
McLennan, S., & Grotzinger, J., 2008. The sedimentary rock cycle of Mars. In J. Bell (Ed.), The
Martian Surface: Composition, Mineralogy and Physical Properties (Cambridge Planetary
Science, pp. 541-577). Cambridge: Cambridge University Press.
McLennan, S. M., 2012. Geochemistry of sedimentary processes on Mars. In: J. P. Grotzinger
and R. E. Milliken (eds.) Mars Sedimentology, SEPM Spec. Publ. 102, 119-138.
McLennan, S.M., Grotzinger, J.P., Hurowitz, J.A. and Tosca, N.J., 2019. The sedimentary cycle
on early Mars. Annual Review of Earth and Planetary Sciences, 47, pp.91-118.
Panning, M.P., Beucler, É., Drilleau, M., Mocquet, A., Lognonné, P. and Banerdt, W.B., 2015.
Verifying single-station seismic approaches using Earth-based data: Preparation for data return
from the InSight mission to Mars. Icarus, 248, pp.230-242.
Panning et al., 2022. Locating the largest event observed on Mars with multi-orbit surface waves
(submitted to the GRL S1222a special issue, attached).
Parro, L. M., Jiménez-Diaz, Mansilla, F. and Ruiz, J. (2017) Present-day heat flow models of
Mars. Sci. Rept., 7, 45629.
Posiolova, L.V., Lognonné, P., Banerdt, W.B., Clinton, J., Collins, G.S., Kawamura, T., Ceylan,
S., Daubar, I.J., Fernando, B., Froment, M. and Giardini, D., 2022. Largest recent impact craters
on Mars: Orbital imaging and surface seismic co-investigation. Science, 378(6618), pp.412-417.
Rudnick, R. L. and Fountain, D. M. (1995) Nature and composition of the continental crust: A
lower crustal perspective. Rev. Geophys., 33, 267-309.
Schimmel, M., Stutzmann, E., Lognonné, P., Compaire, N., Davis, P., Drilleau, M., Garcia, R.,
Kim, D., Knapmeyer-Endrun, B., Lekic, V., et al., 2021. Seismic noise autocorrelations on mars,
Earth and Space Science, p. e2021EA001755.
Scholz, J.-R., Widmer-Schnidrig, R., Davis, P., Lognonné, P., Pinot, B., Garcia, R. F., Hurst, K.,
Pou, L., Nimmo, F., Barkaoui, S., et al., 2020. Detection, analysis, and removal of glitches from
InSight’s seismic data from Mars, Earth and Space Science, 7(11), e2020EA001317.
Smith, D.E., Zuber, M.T., Frey, H.V., Garvin, J.B., Head, J.W., Muhleman, D.O., Pettengill, G.H.,
Phillips, R.J., Solomon, S.C., Zwally, H.J. and Banerdt, W.B., 2001. Mars Orbiter Laser
Altimeter: Experiment summary after the first year of global mapping of Mars. Journal of
Geophysical Research: Planets, 106(E10), pp.23689-23722.
Stähler, S. C., Khan, A., Banerdt, W. B., Lognonné, P., Giardini, D., Ceylan, S., Drilleau, M.,
Duran, A. C., Garcia, R. F., Huang, Q., et al., 2021a. Seismic detection of the martian core,
Science, 373(6553), 443–448.
Stähler et al., 2021b. Interior Models of Mars from inversion of seismic body waves (Version
1.0). IPGP Data Center;
Stutzmann, É., Schimmel, M., Lognonné, P., Horleston, A., Ceylan, S., van Driel, M., Stahler, S.,
Banerdt, B., Calvet, M., Charalambous, C. and Clinton, J., 2021. The polarization of ambient
noise on Mars. Journal of Geophysical Research: Planets, 126(1), p.e2020JE006545.
Tanaka, K.L., Skinner Jr, J.A., Dohm, J.M., Irwin III, R.P., Kolb, E.J., Fortezzo, C.M., Platz, T.,
Michael, G.G. and Hare, T.M., 2014. Geologic map of Mars.
Taylor, S. R. and McLennan, S. M. (2009) Planetary Crusts: Their Composition, Origin and
Evolution. Cambridge Univ. Press (Cambridge), 378pp.
Trampert, J. and Woodhouse, J.H., 1996. High resolution global phase velocity distributions.
Geophysical research letters, 23(1), pp.21-24.
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License
20. Accepted
Article
This article is protected by copyright. All rights reserved.
Thiriet, M., Michaut, C., Breuer, D. and Plesa, A.-C. (2018) Hemispheric dichotomy in
lithospheric thickness on Mars caused by differences in crustal structure and composition. J.
Geophys. Res. – Planets, 123, 823-848.
Wieczorek, M.A., Broquet, A., McLennan, S.M., Rivoldini, A., Golombek, M., Antonangeli, D.,
Beghein, C., Giardini, D., Gudkova, T., Gyalay, S. and Johnson, C.L., 2022. InSight constraints
on the global character of the Martian crust. Journal of Geophysical Research: Planets,
p.e2022JE007298.
Xu, Z., Stutzmann, E., Lognonné, P., Schimmel, M., Montagner, J.-P., and Kawamura, T.: Radial
anisotropy from surface-wave observation in Mars, Europlanet Science Congress 2022, Granada,
Spain, 18–23 Sep 2022, EPSC2022-863, https://doi.org/10.5194/epsc2022-863.
Zhong, S. and Zuber, M.T., 2001. Degree-1 mantle convection and the crustal dichotomy on
Mars. Earth and Planetary Science Letters, 189(1-2), pp.75-84.
Zhou, Y., Dahlen, F.A. and Nolet, G., 2004. Three‐dimensional sensitivity kernels for surface
wave observables. Geophysical Journal International, 158(1), pp.142-168.
Beghein, Caroline, J. Arthur Snoke, and Matthew J. Fouch. "Depth constraints on azimuthal anisotropy in
the Great Basin from Rayleigh-wave phase velocity maps." Earth and Planetary Science Letters 289,
no. 3-4 (2010): 467-478.
Wilson, Lionel, and James W. Head III. "Mars: Review and analysis of volcanic eruption theory and
relationships to observed landforms." Reviews of Geophysics 32, no. 3 (1994): 221-263.
Hahn, B. C., S. M. McLennan, and E. C. Klein. "Martian surface heat production and crustal heat flow from Mars
Odyssey Gamma‐Ray spectrometry." Geophysical Research Letters 38, no. 14 (2011).
Manga, Michael, and Vanshan Wright. "No Cryosphere‐Confined Aquifer Below InSight on Mars." Geophysical
Research Letters 48, no. 8 (2021): e2021GL093127.
Stutzmann, É., Schimmel, M., Lognonné, P., Horleston, A., Ceylan, S., van Driel, M., Stahler, S., Banerdt, B.,
Calvet, M., Charalambous, C. and Clinton, J., 2021. The polarization of ambient noise on Mars. Journal of
Geophysical Research: Planets, 126(1), p.e2020JE006545.
InSight Mars SEIS Data Service. (2019). SEIS raw data, Insight Mission. IPGP, JPL, CNES, ETHZ, ICL, MPS, ISAE‐
Supaero, LPG, MFSC. https://doi.org/10.18715/SEIS.INSIGHT.XB_2016
19448007,
ja,
Downloaded
from
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101243
by
CAPES,
Wiley
Online
Library
on
[19/12/2022].
See
the
Terms
and
Conditions
(https://onlinelibrary.wiley.com/terms-and-conditions)
on
Wiley
Online
Library
for
rules
of
use;
OA
articles
are
governed
by
the
applicable
Creative
Commons
License