Active and passive surface wave methods were used to image subsurface shear wave slowness at the Coyote Creek field site. Comparisons of slowness profiles from different methods showed generally good agreement, with most methods predicting larger near-surface slowness and smaller deep slowness compared to the reference model. Site amplification estimates based on the different slowness models were also generally similar. The blind interpretation experiment demonstrated that surface wave methods can provide robust shear wave velocity structures when multiple independent interpretations are considered.
Seismic Refraction Test
Subsurface investigation by seismic refraction
Seismic Data Analysis
Seismic refraction instrumental set up and operation
P-waves velocity ranges for different strata
It covers seismic method, gravity method, electromagnetic method, magnetic method and radiometric method. all these methods help in mineral exploration
is one of the first steps in
searching for oil and gas resources that directly
affects the land and the landowners Seismic surveys are like sonar on steroids They are based on recording the time it takes for sound waves generated by controlled energy sources .The survey usually requires people and machinery
to be on private property and may result in
disturbances of the land such as the clearing of
trees
Seismic Refraction Test
Subsurface investigation by seismic refraction
Seismic Data Analysis
Seismic refraction instrumental set up and operation
P-waves velocity ranges for different strata
It covers seismic method, gravity method, electromagnetic method, magnetic method and radiometric method. all these methods help in mineral exploration
is one of the first steps in
searching for oil and gas resources that directly
affects the land and the landowners Seismic surveys are like sonar on steroids They are based on recording the time it takes for sound waves generated by controlled energy sources .The survey usually requires people and machinery
to be on private property and may result in
disturbances of the land such as the clearing of
trees
Geophysical logging techniques used to support environmental site remediation. Also referred to as borehole geophysical logging and geophysical well logging, the techniques support site characterization and remedial design efforts at properties with groundwater impacted by discharges of contaminants, including Superfund (CERCLA) and other sites where dense, non-aqueous phase liquids (DNAPL) may be present in fractured bedrock and unconsolidated aquifers. The logging methods described include: Natural Gamma; Caliper; Acoustic Televiewer (ATV), also known as Acoustic Borehole Imager (ABI); Optical Televiewer (OTV), also known as Optical Borehole Imager (OBI); Electrical Resistivity, also known as Normal Resistivity; Single Point Resistance; Fluid Resistivity; Fluid Temperature; Heat Pulse Flow Meter (HPFM). Information is provided about how geophysical logs can assist in developing a Conceptual Site Model (CSM), with attention to structural geologic constraints on groundwater monitoring system design, referencing example conditions from the dipping sedimentary rocks of the Newark Basin and unconsolidated sediments of the New Jersey Coastal Plain. The presentation is meant to be of use to a wide range of investigators, including geologists, hydrogeologists, engineers and regulators responsible for site remediation.
Rocks mechanics and its application in mining geology.
It aims at enhancing the mining process and higher yielding by reducing the chance of failures by providing information about the rocks of the mining area.
2 d and 3d land seismic data acquisition and seismic data processingAli Mahroug
The seismic method has three important/principal applications
a. Delineation of near-surface geology for engineering studies, and coal and mineral
exploration within a depth of up to 1km: the seismic method applied to the near –
surface studies is known as engineering seismology.
b. Hydrocarbon exploration and development within a depth of up to 10 km: seismic
method applied to the exploration and development of oil and gas fields is known
as exploration seismology.
c. Investigation of the earth’s crustal structure within a depth of up to 100 km: the
seismic method applies to the crustal and earthquake studies is known as
earthquake seismology.
Geophysical logging techniques used to support environmental site remediation. Also referred to as borehole geophysical logging and geophysical well logging, the techniques support site characterization and remedial design efforts at properties with groundwater impacted by discharges of contaminants, including Superfund (CERCLA) and other sites where dense, non-aqueous phase liquids (DNAPL) may be present in fractured bedrock and unconsolidated aquifers. The logging methods described include: Natural Gamma; Caliper; Acoustic Televiewer (ATV), also known as Acoustic Borehole Imager (ABI); Optical Televiewer (OTV), also known as Optical Borehole Imager (OBI); Electrical Resistivity, also known as Normal Resistivity; Single Point Resistance; Fluid Resistivity; Fluid Temperature; Heat Pulse Flow Meter (HPFM). Information is provided about how geophysical logs can assist in developing a Conceptual Site Model (CSM), with attention to structural geologic constraints on groundwater monitoring system design, referencing example conditions from the dipping sedimentary rocks of the Newark Basin and unconsolidated sediments of the New Jersey Coastal Plain. The presentation is meant to be of use to a wide range of investigators, including geologists, hydrogeologists, engineers and regulators responsible for site remediation.
Rocks mechanics and its application in mining geology.
It aims at enhancing the mining process and higher yielding by reducing the chance of failures by providing information about the rocks of the mining area.
2 d and 3d land seismic data acquisition and seismic data processingAli Mahroug
The seismic method has three important/principal applications
a. Delineation of near-surface geology for engineering studies, and coal and mineral
exploration within a depth of up to 1km: the seismic method applied to the near –
surface studies is known as engineering seismology.
b. Hydrocarbon exploration and development within a depth of up to 10 km: seismic
method applied to the exploration and development of oil and gas fields is known
as exploration seismology.
c. Investigation of the earth’s crustal structure within a depth of up to 100 km: the
seismic method applies to the crustal and earthquake studies is known as
earthquake seismology.
PetroTeach Free Webinar by Dr. Andrew Ross on Seismic Reservoir CharacterizationPetro Teach
A reliable reservoir model is an invaluable tool for risk reduction. I will give an overview of seismic reservoir characterization and the quantitative interpretation workflow including the use of pre and post stack seismic attributes and inversion outputs for mapping reservoir properties and integration of the attribute output with petrophysical data to create quantitative reservoir models.
PetroTeach Free Webinar on Seismic Reservoir CharacterizationPetroTeach1
A reliable reservoir model is an invaluable tool for risk reduction. Dr. Andrew Ross gave an overview of seismic reservoir characterization and the quantitative interpretation workflow including the use of pre and post-stack seismic attributes and inversion outputs for mapping reservoir properties and integration of the attribute output with petrophysical data to create quantitative reservoir models.
Seismic data Interpretation On Dhodak field PakistanJamal Ahmad
I (Jamal Ahmad) presented this on 21 Feb, 2009 to defend my M.Phil dissertation in Geophysics at QAU, Islamabad, Pakistan. For more information about this, you may contact me directly at jamal.qau@gmail.com.
This is for student of geophysics who want to know about basic of multi component seismic. For further detail or any query you can drop me mail, my mail id id bprasad461@gmail.com
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
2. Predicting Site Response
• Based on theoretical calculations
– 1-D equivalent linear, non-linear
– 2-D and 3-D non-linear
• Needs geotechnical site properties
3. Imaging of Near-Surface Seismic
Slowness (Velocity) and Dampingand Damping
Ratios (Q)Ratios (Q)
4. • Sβ(z)(shear-wave slowness) (=1/velocity)
• Sα(z)(compressional-wave slowness)
• ξβ(z) (shear-wave damping ratio [Qβ])
Image What?Image What?
Why?Why?
• Site amplification
• Site classification for building codes
• Identification of liquefaction and landslide potential
• Correlation of various properties (e.g., geologic units and Vs)
5. Why Slowness?
• Travel time in layers directly proportional to slowness; travel
time fundamental in site response (e.g., T = 4*s*h = 4*travel
time)
• Can average slowness from several profiles depth-by-depth
• Slowness is the usual regression coefficient in fits of travel
time vs. depth
• Visual comparisons of slowness profiles more
meaningful for site response than velocity
profiles
6. Why Show Slowness Rather Than Velocity?
Large apparent differences in velocity in deeper layers (usually
higher velocity) become less important in plots of slowness
Focus attention on what contributes most to travel time in the layers
0 2 4 6
0
20
40
60
80
100
Shear-Wave Slowness (sec/km)
Depth(m)
Garner Valley
SASW Testing
Downhole Seismic
File:C:esg2006papergarner_valley_velocity_slowness_4ppt.draw;Date:2006-08-19;Time:09:00:59
0 500 1000 1500
0
20
40
60
80
100
Shear-Wave Velocity (m/sec)
Depth(m)
10. SURFACE SOURCE ---SUBSURFACE RECEIVERS
• downhole profiling
– velocities from surface
– data gaps filled by average velocity
– expensive (requires hole)
– depth range limited (but good to > 250 m)
• seismic cone penetrometer
– advantages of downhole
– inexpensive
– limited range
– not good for cobbly materials, rock
11. 00.2
0 5 10 15 20 25 30 35 40 45 50
TravelTime(sec)
0.4
velTime(sec)
ile:C:coycreekgibbsjimCOYC_f_r_0_100_sideways_4ppt.draw;Date:2006-08-16;Time:17:27:18
Plotting sideways makes it
easier to see slopes changes
by viewing obliquely (an
exploration geophysics
trick)
Create a record
section—opposite
directions of
surface source
(red, blue traces)
Pick arrivals (black)
CCOC
12. 0 50 100 150 200 250
0
0.2
0.4
0.6
TravelTime(sec)
sig = 1
sig = 2
sig = 3
sig = 4
sig = 5
model
CCOC -- 18 layers
-0.002
0
0.002
0.004
Residuial(sec)
ile:C:coycreekgibbsCoys_detail3_tt_resids_4ppt.draw;Date:2006-08-17;Time:08:26:11
Finer layering
in upper 100m
13. 0 1 2 3 4 5 6
0
50
100
150
200
250
Slowness (sec/km)
Depth(m)
CCOC: S-Wave Slowness
Gibbs (Vs(30) = 232 m/s)
More detail (Vs(30) = 235 m/s)
File:C:coycreekgibbsgibbs_detail3_slowness_300m_4ppt.draw;Date:2006-08-19;Time:09:26:14
Two models
from the same
travel time
picks.
14. 0.1 1 10
0.1
0.2
1
2
10
Frequency (Hz)
Amplification
8 layers
18 layers
vertical incidence,
density=2 gm/cc, Q
= 25, and a
halfspace with
V=1200 m/s and
density = 2.4 gm/cc
at 234 m depth.
File:C:coycreekgibbsnrattle_amps_gibbs_few_more_layers.draw;Date:2006-08-17;Time:08:34:45
The increased
resolution
makes little
difference in
site
amplification
15. SUBSURFACE SOURCE --- SUBSURFACE RECEIVERS
• crosshole
– “point” measurements in depth
– expensive (2 holes)
– velocity not appropriate for site response
• suspension logger
– rapid collection of data (no casing required)
– average velocity over small depth ranges
– can be used in deep holes
– expensive (requires borehole)
– no way of interpolating across data gaps
16. Cable Head
Head Reducer
Upper Geophone
Lower Geophone
Filter Tube
Source
Source Driver
Weight
Winch
7-Conductor cable
Diskette
with Data
OYO PS-160
Logger/Recorder
Overall Length ~ 25 ft
From Geovision
Downhole source--- P-S suspensionDownhole source--- P-S suspension logging (aka “PS Log”)logging (aka “PS Log”)
Dominant
frequency =
1000 Hz
17. Example from
Coyote Creek:
note 1) overall
trend; 2)
“scatter”; 3)
results
averaged over
various depth
intervals
reduces
“noise”
0 2 4 6 8
0
50
100
150
200
250
300
slowness (sec/km)
Depth(m)
CCOC: (Steller)
suspension log values
average of slowness over 5 m intervals
average of slowness over 10 m intervals
File:C:coycreekstellersuscoysx_slowness_300m_4ppt.draw;Date:2006-08-30;Time:02:16:10
19. Some Strengths of Invasive Methods
• Direct measure of velocity
• Surface source produces a model from the surface,
with depth intervals of poor or missing data replaced
by average layer (good for site amplification
calculations)
• PS suspension logging rapid, can be done soon after
hole drilled, no casing required, not limited in depth
range
20. Some Weaknesses of Invasive Methods
• Expensive! (If need to drill hole)
• Surface source may have difficulties in deep holes,
requires cased holes, logging must wait
• PS suspension log does not produce model from the
surface (but generally gets to within 1 to 2 m), and
there is no way of interpolating across depth
intervals with missing data.
21. Noninvasive Methods
• Active Sources
– e.g., SASW and MASW
• Passive sources (usually
microtremors)
– Single station
– Arrays (e.g., fk, SPAC)
• Combined active—passive sources
22. Overview of SASW and MASW
Method
• Spectral-Analysis-of-Surface-Waves
(SASW—2 receivers); Multichannel
Analysis of Surface Waves (MASW—
multiple receivers)
• Noninvasive and Nondestructive
• Based on Dispersive Characteristics of
Rayleigh Waves in a Layered Medium
23. SASW Field Procedure
• Transient or
Continuous Sources
(use several per
site)
• Receiver Geometry
Considerations:
– Near Field Effects
– Attenuation
– Expanding
Receiver Spread
– Lateral Variability
(Brown)
24. SASW & MASW Data Interpretation
80
60
40
20
0
Depth,m
8006004002000
Shear Wave Velocity, VS, m/s
Rinaldi Receiving Station
1
10
100
Wavelength,λRm
6004002000
Surface Wave Velocity, VR, m/s
Experimental Data
Theoretical Dispersion Curve
Rinaldi Receiving Station
(Brown)
Dispersion curve built from a number of subsets (different
source, different receiver spreads)
25. Some Factors That Influence
Accuracy of SASW & MASW Testing
• Lateral Variability of Subsurface
• Shear-Wave Velocity Gradient and
Contrasts
• Values of Poisson’s Ratio Assumed
in the inversion of the dispersion
curves
• Background Information on Site
Geology Improves the Models
26. Noninvasive Methods
• Passive sources (usually
microtremors)
– Single station (much work has been
done on this method---e.g., SESAME
project. I only mention it in passing,
using some slides from an ancientancient
paper)
27. (Boore & Toksöz, 1969)
Ellipticity (H/V) as a function of frequency depends on earth structure
31. Noninvasive Methods
• Often active sources are limited in
depth (hard to generate low-
frequency motions)
• Station spacing used in passive
source experiments often too large
for resolution of near-surface
slowness
• Solution: Combined active—passive
sources
32. (Yoon and Rix, 2005)
An example
from the
CCOC—WSP
experiment
(active: f > 4
Hz; passive:
f<8 Hz)
33. Comparing Different Imaging Results at the
Same Site
• Direct comparison of slowness profiles
• Site amplification
– From empirical prediction equations
– Theoretical
• Full resonance
• Simplified (Square-root impedance)
34. Comparison of
slowness profiles:
0 2 4 6
0
20
40
60
80
100
Shear-Wave Slowness (sec/km)
Depth(m)
Garner Valley
PS Log A
PS Log B
SASW Testing
Downhole Seismic
File:C:esg2006papergarner_valley_slowness_4ppt.draw;Date:2006-08-22;Time:15:54:42
35. Coyote Creek Blind Interpretation Experiment (Asten and
Boore, 2005)
CCOC = Coyote Creek
Outdoor Classroom
36. The Experiment
• Measurements and interpretations done voluntarily
by many groups
• Interpretations “blind” to other results
• Interpretations sent to D. Boore
• Workshop held in May, 2004 to compare results
• Open-File report published in 2005 (containing a
summary by Asten & Boore and individual reports
from participants)
37. 0 2 4 6 8 10
0
20
40
60
80
100
Slowness (sec/km)
Depth(m)
Shear Wave
Reference model
Reflection (Williams)
SASW (Bay, forward)
SASW (Stokoe, avg lb, ub)
SASW (Kayen, Wave-Eq)
MASW (Stephenson)
WSP: Active Sources
File:C:coycreekpaperwsp_active_s_deep_shallow.draw;Date:2006-08-19;Time:11:45:50
0 2 4 6 8 10
0
10
20
30
40
Slowness (sec/km)
Shear Wave
Reference model
Reflection (Williams)
SASW (Bay, forward)
SASW (Stokoe, avg lb, ub)
SASW (Kayen, Wave-Eq)
MASW (Stephenson)
WSP: Active Sources
Active sources at WSP: note larger near-surface & smaller
deep slownesses than reference for most methods.
38. 0 2 4 6 8 10
0
50
100
150
200
250
300
Slowness (sec/km)
Depth(m)
Shear Wave
Reference model
SPAC (Asten, pkdec2)
SPAC (Hartzell)
H/V (Lang, Oct04)
Remi (Stephenson, mar05)
Remi (Louie)
WSP: Passive Sources
File:C:coycreekpaperwsp_passive_s_deep_shallow.draw;Date:2006-08-19;Time:11:46:18
0 2 4 6 8 10
0
10
20
30
40
Slowness (sec/km)
Shear Wave
Reference model
SPAC (Asten, pkdec2)
SPAC (Hartzell)
H/V (Lang, Oct04)
Remi (Stephenson, mar05)
Remi (Louie)
WSP: Passive Sources
Passive sources at WSP: note larger near-surface & smaller
deep slownesses than reference for most methods. Models
extend to greater depth than do the models from active
sources
39. 0 2 4 6 8 10
0
10
20
30
40
Slowness (sec/km)
Shear Wave
Reference model
MASW+MAM (Hayashi)
MASW+MAM (Rix)
WSP: Active + Passive Sources
File:C:coycreekpaperwsp_both_s_deep_shallow.draw;Date:2006-08-19;Time:11:47:00
0 2 4 6 8 10
0
50
100
150
200
Slowness (sec/km)
Depth(m)
Shear Wave
Reference model
MASW+MAM (Hayashi)
MASW+MAM (Rix)
WSP: Active + Passive Sources
Combined active & passive sources at WSP: note larger
near-surface slownesses than reference
40. 0.01 0.1 1 10
0.8
0.9
1
1.1
Period (s)
Amplification,relativetotheV30fromtheCCOCboreholeaverage
Red: Active Sources; Blue: Passive & Combined Sources
SASW, CCOC (Stokoe, Cl1)
SASW, CCOC (Stokoe, Cl2 avg)
Reflection, WSP (Williams)
SASW, WSP (Kayen)
MASW, WSP (Stephenson)
SASW, WSP (Stokoe, avg)
MASW+MAM, WSP (Hayashi)
MASW+FK, WSP (Rix)
H/V, WSP (Lang, oct04)
SPAC, WSP (Asten, pkdec2)
SPAC, WSP (Hartzell)
ReMi (Stephenson, mar05)
ReMi (Louie)
File:C:coycreekpaperamps_using_v30.draw;Date:2006-08-18;Time:08:40:28
leading to these small differences in empirically-based
amplifications based on V30 (red=active; blue=passive &
combined)
41. Average slownesses tend to converge near 30 mconverge near 30 m (coincidence?) with
systematic differences shallower and deeper (both types of source give larger
shallow slowness; at 30 m the slowness from active sources is larger than the
reference and on average is smaller than the reference for passive sources.
0 2 4 6 8 10
1
2
10
20
100
200
Slowness (sec/km)
Depth(m)
Active Sources (CCOC & WSP)
reference model
SASW, CCOC (Bay)
SASW, CCOC (Stokoe, CL1)
SASW, CCOC (Stokoe, CL2 avg)
reflection, WSP (Williams)
SASW, WSP (Bay)
SASW, WSP (Kayen)
MASW, WSP (Stephenson)
SASW, WSP (Stokoe, avg)
0 2 4 6 8 10
1
2
10
20
100
200
Slowness (sec/km)
Passive & Combined Sources (WSP)
reference model
SPAC (Asten, pkdec2)
H/V (Lang, oct04)
SPAC (Hartzell)
ReMi (Stephenson, mar05)
ReMi (Louie)
MASW+MAM, WSP (Hayashi)
MASW+FK, WSP (Rix)
File:C:coycreekpaperccoc_wsp_slowness_active_passive.draw;Date:2006-08-23;Time:09:24:19
42. 1 2 10 20
2
3
4
Frequency (Hz)
Amplification(relativeto1500m/s;nodamping)
Active Sources
reference model
SASW, CCOC (Bay)
SASW, CCOC (Stokoe, CL1)
SASW, CCOC (Stokoe, CL2 avg)
Reflection, WSP (Williams)
SASW, WSP (Bay)
SASW, WSP (Kayen)
MASW, WSP (Stephenson)
SASW, WSP (Stokoe, avg)
reference model with damping ( =0.04s)
Kayen, with damping ( =0.04s)
1 2 10 20
2
3
4
Frequency (Hz)
Passive & Combined Sources (WSP)
reference model
SPAC, WSP (Asten, pkdec2)
H/V, WSP (Lang, oct04)
SPAC, WSP (Hartzell)
ReMi, WSP (Stephenson_mar05)
ReMi, WSP (Louie)
MASW+MAM, WSP (Hayashi)
MASW+FK, WSP (Rix)
File:C:coycreekpaperccoc_wsp_amps_active_passive.draw;Date:2006-08-18;Time:08:43:32
But larger differenceslarger differences at higher frequenciesat higher frequencies (up to 40%)
(V30 corresponds to ~ 2 Hz)
43. Summary (short)
• Many methods available for imaging seismic
slowness
• Noninvasive methods work well, with some
suggestions of systematic departures from borehole
methods
• Several measures of site amplification show little
sensitivity to the differences in models (on the order
of factors of 1.4 or less)
• Site amplifications show trends with V30, but the
remaining scatter in observed ground motions is
large
Editor's Notes
The Spectral analysis of surface waves method is the successor to the steady state Rayleigh wave method developed in the 1950’s. Much of the development of the modern SASW method was carried out at UT Austin in the early 1980’s.
SASW testing is used to obtain a shear wave velocity profile
It is non-invasive and non-destructive - testing is performed on the ground surface and strains are in the elastic range
Instead of measuring shear wave velocity directly, Rayleigh wave velocities are measured and Vs is inferred.
The general testing setup is shown here. A seismic source generates surface waves, which are monitored by two in-line receivers.
Both transient and continuous dynamic sources are used to generate surface waves, with the data usually cleaner from continuous swept-sine sources. A vibroseis truck (slide) was used for the long wavelengths and various hand-held hammers (slide) were used for the short wavelengths.
Several factors must be considered in receiver geometry. To avoid near field effects associated with Rayleigh waves and body waves, the distance from the source to the receiver, d1, is at least half of the maximum recorded wavelength. Attenuation reduces signal quality if d1 is greater than 4-10 wavelengths, depending on the source. Therefore, an expanding receiver spread is used, with overlap between the wavelengths recorded in each setup.
To minimize lateral variability, forward and reverse profiles are taken, usually with a common centerline. The time records from the two geophones are transformed to the frequency domain to generate the dispersion curve. The most important data are the phase of the cross-power spectrum and the coherence.
It is important that the frequency domain calculation be done in the field so that the experiment can be modified as needed.
From the unwrapped phase of the cross power spectrum, the Rayleigh wave velocity is calculated, given the frequency and interreceiver distance.
The dispersion curves from each receiver spacing are combined to generate the composite dispersion curve, which is representative of the site.
Several theoretical solutions are used to model the dispersion curve: Fundamental mode Rayleigh waves only, and full stress wave solutions that incorporate higher modes of Rayleigh wave propagation, body wave energy, and receiver location. The full stress wave solution generally gives better results so the results from that model will be shown.
The parameters in the layered earth model used to calculate the dispersion curve consist of layer thickness, shear wave velocity, Poisson’s ratio, and mass density. Usually only shear wave velocity and layer thickness are adjusted to match the dispersion curve, since they have the largest influence.
The resolvable depth varies from about one half the longest wavelength to one fifth or less, depending on the site.
Obviously, the results from SASW testing were closer to those from downhole testing at some sites. There are several possible reasons for this;
SASW testing samples a much larger volume of material than downhole testing. The SASW results are averaged across several hundred meters. If the subsurface varies laterally or is non-homogeneous the material sampled in SASW and downhole seismic testing may be different.
At sites where the shear wave velocity increases gradually, the SASW data are easiest to interpret and most accurate. Large shear-wave velocity gradients limit the resolvable depth, because the dispersion curve never levels out to a velocity representative of individual layers or a half space. SASW testing does not resolve layer boundaries as well as average properties. Interface resolution also decreases with depth.
The value of Poisson’s ratio assumed in the model for Rayleigh wave dispersion has a greater effect than is often thought. A sensitivity study showed that in saturated sediments.
