The document discusses the methods for near-surface seismic refraction surveying. It describes typical equipment used including seismographs, sensors, spread cables, and sources. It outlines survey geometry considerations for sensor and source placement. It also details typical recording parameters, the analysis process of picking first breaks and inverting travel time curves, and references additional analysis techniques and software.
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
This Lecture includes the Resistivity survey, field procedure, application advantage, limitaion, Apparant resistivity, VES (Vertical Electrical Sounding), Resistivity Profiling and IP Survey in brief.
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
This Lecture includes the Resistivity survey, field procedure, application advantage, limitaion, Apparant resistivity, VES (Vertical Electrical Sounding), Resistivity Profiling and IP Survey in brief.
The presentation comprises the Gravity Method, It's anomaly, reduction, and its applications. The Gravity method is commonly used in Geology specifically in Geophysics.
Introduction
Petrophysic of the rocks
It is the study of the physical and chemical properties of the rocks related to the pores and fluid distribution
Porosity, is ratio between volume of void to the total voids of the rock.
Permeability, is ability of a porous material to allow fluids to pass through it.
Electric, most of the sedimentary rocks don’t have conductivity.
Radiation, clay rocks have 40K, radiate alpha ray.
Hardness, it depends on the cementing material and thickness of the sediments.
WELL LOGGING
The systematic recording of rock properties and it’s fluid contents in wells being drilled or produced to obtain various petrophysical parameters and characteristics of down hole sequences (G.E Archie 1950).
The measurement versus depth or time, or both, of one or more physical properties in a well.
These methods are particularly good when surface outcrops are not available, but a direct sample of the rock is needed to be sure of the lithology.
A wide range of physical parameters can be measured.
In some cases, the measurements are not direct, it require interpretation by analogy or by correlating values between two or more logs run in the same hole.
Provide information on lithology, boundaries of formations and stratigraphic correlation.
Determine Porosity, Permeability, water, oil and gas saturation.
Reservoir modeling and Structural studies… etc.
Types of Well Logging
Logs can be classified into several types under different category
Permeability and lithology Logs
Gamma Ray log
Self Potential [SP] log
Caliber log
Porosity Logs
Density log
Sonic log
Neutron log
Electrical Logs
Resistivity Log
For contact : omerupto3@gmail.com
Borehole geophysics is the science of recording and analyzing measurements of physical properties made in wells or test holes. Probes that measure different properties are lowered into the borehole to collect continuous or point data that is graphically displayed as a geophysical log. Multiple logs typically are collected to take advantage of their synergistic nature--much more can be learned by the analysis of a suite of logs as a group than by the analysis of the same logs individually. Borehole geophysics is used in ground-water and environmental investigations to obtain information on well construction, rock lithology and fractures, permeability and porosity, and water quality. The geophysical logging system consists of probes, cable and drawworks, power and processing modules, and data recording units. State-of-the-art logging systems are controlled by a computer and can collect multiple logs with one pass of the probe
The presentation comprises the Gravity Method, It's anomaly, reduction, and its applications. The Gravity method is commonly used in Geology specifically in Geophysics.
Introduction
Petrophysic of the rocks
It is the study of the physical and chemical properties of the rocks related to the pores and fluid distribution
Porosity, is ratio between volume of void to the total voids of the rock.
Permeability, is ability of a porous material to allow fluids to pass through it.
Electric, most of the sedimentary rocks don’t have conductivity.
Radiation, clay rocks have 40K, radiate alpha ray.
Hardness, it depends on the cementing material and thickness of the sediments.
WELL LOGGING
The systematic recording of rock properties and it’s fluid contents in wells being drilled or produced to obtain various petrophysical parameters and characteristics of down hole sequences (G.E Archie 1950).
The measurement versus depth or time, or both, of one or more physical properties in a well.
These methods are particularly good when surface outcrops are not available, but a direct sample of the rock is needed to be sure of the lithology.
A wide range of physical parameters can be measured.
In some cases, the measurements are not direct, it require interpretation by analogy or by correlating values between two or more logs run in the same hole.
Provide information on lithology, boundaries of formations and stratigraphic correlation.
Determine Porosity, Permeability, water, oil and gas saturation.
Reservoir modeling and Structural studies… etc.
Types of Well Logging
Logs can be classified into several types under different category
Permeability and lithology Logs
Gamma Ray log
Self Potential [SP] log
Caliber log
Porosity Logs
Density log
Sonic log
Neutron log
Electrical Logs
Resistivity Log
For contact : omerupto3@gmail.com
Borehole geophysics is the science of recording and analyzing measurements of physical properties made in wells or test holes. Probes that measure different properties are lowered into the borehole to collect continuous or point data that is graphically displayed as a geophysical log. Multiple logs typically are collected to take advantage of their synergistic nature--much more can be learned by the analysis of a suite of logs as a group than by the analysis of the same logs individually. Borehole geophysics is used in ground-water and environmental investigations to obtain information on well construction, rock lithology and fractures, permeability and porosity, and water quality. The geophysical logging system consists of probes, cable and drawworks, power and processing modules, and data recording units. State-of-the-art logging systems are controlled by a computer and can collect multiple logs with one pass of the probe
This content presents GNSS observation by two main positioning solutions including kinematic application for movement and static applications for more accurate measurement. Moreover, survey method and procedure guidelines are described here.
Gravimetri Dersi için aşağıda ki videoları izleyebilirsiniz.
Link 01: https://www.youtube.com/watch?v=HTyjVaVGx0k
Link 02: https://www.youtube.com/watch?v=fUkfgI8XaOE
Geopsy yaygın olarak kullanılan profesyonel bir program. Özellikle, profesyonel program deneyimi yeni mezunlarda çok aranan bir özellik. Bir öğrencim çalışmasında kullanmayı planlıyor.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Normal Labour/ Stages of Labour/ Mechanism of LabourWasim Ak
Normal labor is also termed spontaneous labor, defined as the natural physiological process through which the fetus, placenta, and membranes are expelled from the uterus through the birth canal at term (37 to 42 weeks
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
1. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 1
Near-Surface Seismic
Refraction Surveying
Field Methods
By Deborah Underwood
Geometrics, Inc.
2. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 2
The seismic refraction method
• First major geophysical method applied to subsurface investigation
of relatively deep oil-bearing geologic structures
• No longer the primary method in oil exploration, but has found use
for near-surface, high-resolution subsurface investigation
• Common applications for civil engineering and environmental studies
include depth-to-bedrock and groundwater investigations; also used
for shallow fault and stratigraphic studies
• Main objective is to measure the time of the “first break”, that is, the
time when a given geophone first moves in response to a seismic
energy source. Simply stated, since time and relative distances of
sources and geophones are known, the velocity of the subsurface
can be calculated
3. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 3
Typical equipment
• Seismograph
– 12 to 24 channels
• Sensors and spread cable
– 8, 10, or 14 Hz vertical geophones
– 2 to 5-m (5 to 20-ft) spread cable takeout interval
• Source
– 10 to 20-pound sledgehammer with hammer switch,
trigger cable, and striker plate
4. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 4
Geometrics seismographs
ES-3000
Laptop controller for
ES-3000 or Geode
Geode
StrataVisor NZ
(PC built-in)
SmartSeis ST
(PC built-in)
5. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 5
Survey geometry – sensors
• Geophones are distributed in a line, signals are transmitted to the
seismograph by a spread cable.
• The total offset should be 3 to 5 times the depth of interest. However, this
should be balanced against the number of channels available and the
required horizontal resolution. If too few channels are used to span a large
total offset, the horizontal resolution will suffer.
SeismographGeophone interval
Total offset
distance between
first and last
geophone
distance between
geophones Spread cable
Geophone
6. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 6
Survey geometry – sources
• At a minimum, there should be two shots (S1, S2) located at either end of
the line. Common practice is to position the shots offset from the line at a
right angle by about one-half the geophone interval. The goal is to position
the shot so it is not too close to a geophone, but also not off-end. For true
comparison of reciprocal times for delay times analysis, end shots should
not be positioned off-end.
• It is best practice to also have one center shot (S3)
• Once the crossover distance(s) is identified, that distance should be
measured off the ends of the line and shots located (S4, S5). Off-end shots
allow you to use all the geophones to sample the refractor.
• Depending on the survey objective, quarter shots (S6, S7) in the interior of
the spread and more distant off-end shots may be desired.
S1 S6 S7 S2S4 S3 S5
Off-end shot distance
approximately equal
to crossover
distance
7. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 7
Survey geometry – sources (cont.)
• Instead of a perpendicular offset for the end shots, the end geophone can be
moved inward by one-half an interval and the shot positioned on the end.
S1 G24
G1 S2
• For S1, the geophone on the right end has normal spacing, and for S2, the geophone
on the left end has been returned to the normal spacing.
• This method allows the most accurate analysis of reciprocal times because the shots
are exactly located on the ends of the line. In theory, the time it takes for energy to
travel from S1 to G24 and from S2 to G1 should be identical.
• If end shots were located off-end (below), the travel paths would be different.
S1 G24
G1 S2
8. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 8
Survey geometry – coordinates
• At a minimum, relative x, y spacing is required
– Easiest to save to the file header at time of acquisition, but can
also be assigned in data analysis software
– Set y equal to zero, and vary x values only (or vice versa)
– Some deviation from a line can be tolerated, minimize deviation
to 5% or less of the line length
• If there is any vertical relief on the line, the elevations
should be surveyed
– Elevations only need be relative, unless referenced elevations are
desired
– Z values are not saved in file header, but are easily input into
data analysis software
9. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 9
Typical recording parameters
• Sample interval: 0.125 to 0.25 ms (over-sampling is fine)
• Record length: 0.25 to 0.5 s (should be long enough to capture
distant arrivals)
• Stacking: as needed to increase signal to noise ratio, 5 to 10 times
• Delay: -10 ms allows the first break on the near geophones to be
more easily viewed
• Acquisition filters: acquisition filters are NOT recommended because
effect is irreversible; should be carefully applied to filter signal you
are certain you will never want such as 60 Hz power line noise
• Preamp gains: highest setting
• Display gains: fixed gain (same gain over time for a given trace, but
variable from trace to trace; traces far from the source will need a
higher gain setting than those that are near)
10. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 10
Analysis of the first end shot
crossover
*Commonly incorrectly referred to as the
“critical distance”
• Analyze waveform file of the
first end shot
– What is the data quality?
There is little pre-first break
noise, the first breaks are
obvious. Quality is excellent.
– How many refractions are
there? One break in slope
indicates one refraction (two-
layers).
– What is the crossover
distance*? Break in slope is
5 traces in. Five multiplied by
a geophone interval of 2m
equals 10m.
11. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 11
Complete dataset
S1 S2S4 S6 S3 S7 S5
12. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 12
Picking first breaks
• Set the display gains
so the first breaks are
clearly visible
– Ground roll has a
relatively large
amplitude and can be
misidentified as the
first arrival if the
display gains are not
high enough
– Use display clipping
so the traces do not
overlap when the
gain is set very high
ground rollfirst breaks
13. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 13
Picking first breaks (cont.)
X (m) T (ms)
• Consistently pick the
same event from trace
to trace and from shot
record to shot record
– Adjust gains as
needed during
picking to optimize
display
• Output data consists of
a travel time (T) for
each geophone
location (X), data used
to plot travel time
curve
travel time curve
14. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 14
Complete set of picks
reciprocal
times
• Reciprocal
times are
about equal
(good quality
check)
• The forward
and reverse
shots are
symmetrical
about the
center
indicating
there is little
or no dip on
refractor
15. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 15
Complete analysis process
green picks:
second layer
red picks:
first layer
Travel time curves
• Pick first breaks
• Select analysis method
– Time-term inversion
gives a quick solution
for 2 to 3-layer cases
with evident breaks in
slope
• Assign layers
• Input elevations (if
applicable)
• Run inversion
• Compare calculated to
observed data
• Final layered model
result
Layered model result
Vp = 2750 m/s
Vp = 500 m/s
16. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 16
Additional topics
• Multiple spreads for long survey lines
– Set up available channels/geophones at desired interval for the
first spread
– Locate and take shot points as if entire line is instrumented with
geophones
– Move geophones to next spread
– Reoccupy the same shot points
– Repeat process until entire line has been covered by spreads
– Append together shot records from each spread by common
shot point in SeisImager/2D refraction data analysis software
• Use of horizontal geophones for shear-wave refraction
surveys
– Records of polarized shear waves can be displayed together in
SeisImager/2D to allow picking of the first break
17. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 17
Additional topics (cont.)
• Other methods offered by SeisImager/2D, require high
data redundancy
– Reciprocal method for detailed analysis of travel time curves,
calculate delay times manually (vs. Time-term inversion where
delay times are calculated automatically)
– Tomographic method for gradational velocity increases with
depth, strong horizontal velocity variation, and extreme
topography
• SeisImager/SW-1D available for surface wave data
analysis for IBC Vs100/Vs30 site classification
– Calculates dispersion curve from surface waves and outputs 1D
curve of shear wave velocity with depth
– For both active and passive (microtremor) sources
• SeisImager/SW-2D available for surface wave data
analysis for 2D cross-sectional imaging of Vs
18. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 18
Surface wave data analysis
Surface wave analysis of refraction shot record S2
Use of 4.5 Hz geophones and a longer record length of 1 to 2 s would
have provided more surface wave data, but still some information can be
gleaned from this refraction record. Not surprisingly, the calculated Vs30
is about one-half of the second layer Vp determined through refraction.
19. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 19
References and
recommended reading
ASTM (1998), Using the Seismic Refraction Method for Subsurface Investigation,
Designation No. D 5777-95.
Fowler, C.M.R. (1990), The Solid Earth: an Introduction to Global Geophysics, Cambridge
University Press.
Geometrics, Inc. (2005), SeisImager/2D Seismic Refraction Data Analysis Software
Manual and Examples Booklet.
Lankston, R.W. (1983), High-resolution Refraction Data Acquisition and Interpretation,
Geo-Compu-Graph, Inc.
Redpath, B.B. (1973), Seismic Refraction Exploration for Engineering Site Investigation,
National Technical Information Service, US Dept. of Commerce.
Reynolds, J.M. (1997), An Introduction to Applied and Environmental Geophysics, John
Wiley and Sons.
Sheriff, R.E. and Geldart, L.P. (1995), Exploration Seismology, Cambridge University Press.
Sjögren, B. (1984), Shallow Refraction Seismics, Chapman and Hall.
20. Geometrics, Inc. - www.geometrics.com - September 2009 r4a 20
For more information
• Geometrics, Inc.
– Telephone
• 408-428-4245
– Email
• seismicsales@geometrics.com
• support@geometrics.com
– Address
• 2190 Fortune Drive
• San Jose, California 95131 USA