1) An integrated geophysical study using seismic refraction and electrical resistivity techniques was conducted to image the shallow subsurface at the University of Peshawar, Pakistan.
2) Analysis of seismic refraction data along profile AB revealed a two-layer subsurface structure, with a top layer of loose soil 0-4 meters thick having P-wave velocities of 223m/sec underlain by a layer with a velocity of 316 m/sec.
3) Electrical resistivity surveys along two profiles validated the two-layer model, detecting a top soil layer 1.1-1.3 meters thick with resistivities of 38-52 ohm-meters underlain by a more conductive clay-rich layer with resist
Ground geophysical surveys use magnetic, electrical, and gravitational measurements to map subsurface rock properties. Magnetics surveys measure the earth's magnetic field and magnetic responses from rocks to map geology and locate magnetic ore bodies. Resistivity and induced polarization (IP) surveys measure electrical properties to detect disseminated sulfides and map stratigraphy. Time-domain electromagnetics (TDEM) uses electromagnetic induction to identify conductive features like ores, groundwater, and permafrost. Geophysical methods provide non-invasive exploration techniques but their results require careful processing and interpretation.
2 d seismic refraction tomography investigation of a sewage treatment siteAlexander Decker
This study used seismic refraction tomography to investigate subsurface layers at a sewage treatment site in Nigeria. Five seismic profiles were collected and analyzed. The results show three layers: an upper undifferentiated overburden layer with velocities from 891-1421 m/s and thicknesses ranging from 18m in the north to 55m in the south; a partially weathered middle layer with velocities from 3010-5129 m/s; and a fresh granite basement layer below with velocities from 5704-7762 m/s. One profile revealed a fracture zone in the basement at 60m depth that could allow sewage to contaminate groundwater if the lagoons are not lined. The study characterized the subsurface
This document provides an introduction to applied geophysics. It discusses relevant textbooks and journals, as well as applications in engineering, environmental studies, mining, and groundwater. Geophysical methods measure physical properties like density, magnetic susceptibility, seismic velocity, resistivity, and dielectric constant. The targets of interest include rock type, pore fluid content, geometry, and other factors that influence porosity, density, strength, and other properties. Proper planning is required to design effective geophysical surveys and interpret the results.
Measurement of Velocity Gradients of Beds At Unwana, Nigeriaiosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
An airborne electromagnetic survey uses aircraft-mounted electromagnetic coils to map variations in ground conductivity. This non-invasive technique can identify metallic conductors like massive sulfides over large areas rapidly and at low cost. Factors like signal-to-noise ratio, penetration depth, discrimination of conductor types, and lateral coverage determine what conductors can be detected. Applications include mineral exploration, environmental mapping, hydrocarbon and groundwater exploration. Survey data is presented as profiles, apparent resistivity maps, and interpretation maps identifying anomaly locations and modeling their conductivity-thickness. Airborne EM has advantages over ground methods in accessing remote areas and efficiently locating targets for follow-up.
Determination of Thickness of Aquifer with Vertical Electrical Sounding iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Role of Geophysics in the Oil and Gas IndustryMusisi Norbert
Geophysics plays an important role in the oil and gas industry by using non-invasive methods to investigate subsurface conditions. Various geophysical survey methods measure physical properties of the subsurface to aid in exploration, mapping resources, and identifying geohazards. Planning geophysical surveys requires selecting the appropriate methods, equipment, and acquisition parameters to meet project objectives and site conditions. Acquired data then undergoes processing and interpretation to develop an understanding of the subsurface.
Ground geophysical surveys use magnetic, electrical, and gravitational measurements to map subsurface rock properties. Magnetics surveys measure the earth's magnetic field and magnetic responses from rocks to map geology and locate magnetic ore bodies. Resistivity and induced polarization (IP) surveys measure electrical properties to detect disseminated sulfides and map stratigraphy. Time-domain electromagnetics (TDEM) uses electromagnetic induction to identify conductive features like ores, groundwater, and permafrost. Geophysical methods provide non-invasive exploration techniques but their results require careful processing and interpretation.
2 d seismic refraction tomography investigation of a sewage treatment siteAlexander Decker
This study used seismic refraction tomography to investigate subsurface layers at a sewage treatment site in Nigeria. Five seismic profiles were collected and analyzed. The results show three layers: an upper undifferentiated overburden layer with velocities from 891-1421 m/s and thicknesses ranging from 18m in the north to 55m in the south; a partially weathered middle layer with velocities from 3010-5129 m/s; and a fresh granite basement layer below with velocities from 5704-7762 m/s. One profile revealed a fracture zone in the basement at 60m depth that could allow sewage to contaminate groundwater if the lagoons are not lined. The study characterized the subsurface
This document provides an introduction to applied geophysics. It discusses relevant textbooks and journals, as well as applications in engineering, environmental studies, mining, and groundwater. Geophysical methods measure physical properties like density, magnetic susceptibility, seismic velocity, resistivity, and dielectric constant. The targets of interest include rock type, pore fluid content, geometry, and other factors that influence porosity, density, strength, and other properties. Proper planning is required to design effective geophysical surveys and interpret the results.
Measurement of Velocity Gradients of Beds At Unwana, Nigeriaiosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
An airborne electromagnetic survey uses aircraft-mounted electromagnetic coils to map variations in ground conductivity. This non-invasive technique can identify metallic conductors like massive sulfides over large areas rapidly and at low cost. Factors like signal-to-noise ratio, penetration depth, discrimination of conductor types, and lateral coverage determine what conductors can be detected. Applications include mineral exploration, environmental mapping, hydrocarbon and groundwater exploration. Survey data is presented as profiles, apparent resistivity maps, and interpretation maps identifying anomaly locations and modeling their conductivity-thickness. Airborne EM has advantages over ground methods in accessing remote areas and efficiently locating targets for follow-up.
Determination of Thickness of Aquifer with Vertical Electrical Sounding iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Role of Geophysics in the Oil and Gas IndustryMusisi Norbert
Geophysics plays an important role in the oil and gas industry by using non-invasive methods to investigate subsurface conditions. Various geophysical survey methods measure physical properties of the subsurface to aid in exploration, mapping resources, and identifying geohazards. Planning geophysical surveys requires selecting the appropriate methods, equipment, and acquisition parameters to meet project objectives and site conditions. Acquired data then undergoes processing and interpretation to develop an understanding of the subsurface.
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.
This document summarizes an electrical resistivity study conducted around Shika, Kaduna State, Nigeria to map subsurface geology. Vertical electrical sounding was performed at 18 locations using an ABEM terrameter. Resistivity values were interpreted to identify topsoil, weathered basement, fractured basement, and fresh basement layers. Topsoil thickness ranged from 1.06-4.14m with resistivity 60-373 ohm-m. Weathered basement thickness was 1.77-33.04m with resistivity 70-708 ohm-m. Fractured basement extended 12.9-26.3m deep with resistivity 318-834 ohm-m. Fresh basement had resistivity over 1161
The Lectures describes the Electrical method of Geophysical Prospecting in brief. SP surveying and Occurrence of Self potential and its application is discussed in brief.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
1) Vertical electrical sounding using Schlumberger array was conducted at 40 stations to determine subsurface layers and depth to bedrock at the Centre for Energy Research and Training in Zaria, Nigeria.
2) Resistivity values and thickness were derived for three predominant layers - topsoil (2-738 ohm-m thickening 1-3.9m), weathered basement (32-1735 ohm-m thickening 0.52-23m), and fresh basement bedrock (100-6036 ohm-m).
3) Results identified areas suitable for structures and boreholes, and recommended depth of sewage systems to avoid groundwater contamination based on the subsurface resistivity and thickness parameters.
Subsurface 2D Image Analyses of the Uyangha Basement Area, South-Eastern NigeriaIOSR Journals
Geo-electric soundings were made in Stella Maris Secondary School, in Uyangha, Nigeria to image
the subsurface and obtain thicknesses and resistivities of different layers. A quantitative interpretation of the
data obtained clearly reveals the presence of four (4) geo-electric sections which are interpreted to be dry
laterite, moist laterite, weathered basement, and saturated basement. The depth probed is about 100m. The
saturated basement is the aquifer unit. Depth to aquifer unit in the area is at about 65m to 80m.The thickness of
the aquifer unit ranges from 20m to 35m. For ground water exploitation, boreholes in the area should therefore
be drilled to the depth of 91m, for reasonable groundwater yield. The lateritic layer makes the study area
suitable for building construction in the area.
The document describes various geophysical lab equipment used for exploration, including their specifications and applications. It discusses the Terrameter SAS 4000 and Terraloc MK-6 used for resistivity and seismic surveys respectively. Other equipment covered are the shielded antenna GPR for medium resolution surveys, gravimeter for gravity surveys, magnetometer for magnetic surveys, portable well logger for shallow well logging, and Mini-Seis seismograph for blast monitoring and earthquake detection. Each equipment is described along with its specifications, accessories, and uses in applications like mineral, oil and gas exploration, engineering projects, and archaeology.
Seismic methods use seismic waves created by impacts on the surface to map underground structures. The waves travel through underground layers and are reflected or refracted at boundaries between different materials. Analysis of the travel times and velocities of the waves allows determining the depth and type of geological layers. Seismic reflection techniques involve creating waves at shot points and recording them with receivers at different offsets to generate common midpoint gathers. Processing the gathers yields a seismic section that images layer boundaries like an echo sounder. Seismic refraction uses refracted head waves along interfaces to build a shallow velocity model for near-surface layers. Both methods together provide structural and physical characterization of underground features like buried valleys.
This document discusses survey design and procedures for electrical resistivity surveys. It describes three common modes: 1) Sounding mode, where electrode spacing is varied to map resistivity with depth at fixed locations. 2) Profiling mode, where electrode spacing is fixed and the array is moved laterally to map lateral resistivity variations. 3) Profiling-sounding mode, which combines aspects of profiling and sounding modes. Common electrode arrays like Wenner and Schlumberger are described for each mode. Sounding and profiling modes are suited for mapping vertical and horizontal resistivity contrasts respectively.
Geophysical prospecting uses physical methods to study the structure of the Earth's crust and locate minerals and ores. It involves collecting data using geophysical methods like seismic, gravitational, magnetic, electrical, and electromagnetic surveys. Seismic methods are commonly used in exploration. They involve generating seismic waves using sources like sledgehammers and analyzing the reflected and refracted waves detected by receivers to characterize subsurface layers and locate resources based on their elastic properties. Proper data acquisition, processing to reduce noise, and geological interpretation of processed seismic data are required to build an accurate model of the subsurface.
The Use of Geophysics In Ground InvestigationClaire_Graham
The document summarizes the services of Stratascan Ltd, a geophysics survey company. It outlines their history, staff capabilities, the techniques they employ including magnetic surveys, earth resistance, ground penetrating radar and more. It provides examples of archaeological and engineering case studies where different techniques were applied successfully or not.
This document discusses refraction seismology, which is a method used to map geologic structures by analyzing the arrival times of seismic head waves that travel through subsurface layers. It provides definitions and references for further reading on refraction seismology and seismic methods. The document also compares refraction seismology to reflection seismology, noting that refraction uses initial seismic arrivals while reflection analyzes later arriving reflected seismic energy to image subsurface structures and boundaries between layers with different seismic velocities.
This study used electrical resistivity imaging, seismic refraction tomography, and azimuthal resistivity soundings to assess an active open dump site in Kaduna, Nigeria. The objectives were to delineate potential leachate plumes and subsurface pathways that could transport contaminants. Results from resistivity imaging identified low resistivity zones (6-33 ohm-m) representing leachate plumes. Resistivity and seismic models also delineated fractures beneath the weathered basement layer that could act as pathways. Longitudinal conductance values of 0.02-0.1 mhos indicated poor protective capacity, allowing leachate to reach shallow aquifers. Azimuthal resistivity soundings at 45 m depth
Application of Very Low Frequency- Electromagnetic (VLF-EM) Method to Map Fra...theijes
Geophysical survey involving very low frequency electromagnetic technique was applied to investigate possible geologic features like fractured / conductive zones in Auchi and its environs in Edo state, Southwestern Nigeria. The study area is located within latitudes 7o 05’ N.to 7o 10’N. and longitudes 6 o 11’E to 6o 22’E The geologic Formations outcroping in the area are mainly Ajali and Nsukka. Three profiles were taken along the roads from Auchi to Igara, Auchi to Fugar and Auchi to Uloke using Abem Wadi Terrameter. Plots of the profiles were carried out using computer software (Excel) and contouring using Surfer 10 to delineate the fractured/conductive zones. The values range from 0.3 to 22.5 Siemens. Areas of low conductivity values indicate highly massive resistive rocks while Areas of high conductivity indicates the sedimentary terrain/ host rock or mineralized zones. The area is sparsely (few) fractured. Along profile A, two fractured zones were identified with conductivity values of 7.6 to16.8 Siemens between 100m(7.146oN,6.195oE) to 400m (7.150oN, 6.200oE) and 420m to 460m with conductivity value range of 11.0 to 22.5 Siemens. For profile B, one fractured zone was identified and a stretch of massive intrusive from 7.099oN and 7.102oN and 6.357oE to 6.364oE, with conductivity range of 0.9 – 5.2 Siemens at points 400m and 520m – 1000m. Profile C has identifiable fractured zones at 900m – 1100m with conductivity of (35 – 50) Siemens. The intrusive/ host rock conductivity values of (0.3 – 8.7) Siemens located at 380m to 880m 7.156oN and 6.308oE, 1100m to 2000m, 7.148oN and 6.3295oE. A total of five conductive zones were observed.
PIPELINE PLANNING WITH AIRBORNE ELECTROMAGNETICSBrett Johnson
This document summarizes the results of a helicopter electromagnetic survey conducted along a 130km pipeline corridor to map subsurface conductivity and aid in pipeline construction planning. The survey identified areas of shallow bedrock that would require blasting versus deeper overburden that could be trenched. Drill holes along the corridor were used to calibrate the electromagnetic conductivity measurements with actual subsurface conditions. A conductivity value of 6mS/m correlated well with a 2m overburden depth, the depth needed for pipeline trenching. The survey effectively mapped subsurface conditions and reduced costs associated with pipeline planning and construction.
This study estimates local site effects in the Ataköy area of Istanbul, Turkey through multiple techniques. A hybrid 3D finite-difference method is used to model site amplification from a scenario earthquake using a 3D velocity model of the local geology. Horizontal-to-vertical spectral ratios are calculated from microtremor recordings at 30 sites and compared to synthetic noise data from a 1D geological model. The results indicate the strongest amplifications around 1 Hz, with alluvial sites expected to experience amplification factors of 1.5-2. Comparing the different methods provides a comprehensive understanding of site effects in this densely populated and seismically hazardous area of Istanbul.
This document summarizes a study that performed broadband frequency simulations of strong ground motion in the Sea of Marmara region of Turkey based on fault rupture scenarios. Three earthquake scenarios were modeled involving rupture of the Central Marmara Fault and North Boundary Fault, which pose the largest hazard to Istanbul. A hybrid technique was used that combines deterministic and semi-stochastic methods. The location of the hypocenter was found to be a critical parameter for predicting ground motions in Istanbul. Anelasticity was also found to significantly affect regional attenuation of peak ground accelerations. The simulated ground motions resulted in large acceleration response spectra at long periods that could be critical for building damage in Istanbul during an actual earthquake.
The document discusses several types of seismic velocity models including 1D layered models, community velocity models based on direct measurements, unified community models, and 3D tomography models derived from active and passive seismic data. It provides details on numerous global and regional reference models for the crust, mantle, and specific tectonic provinces.
Introduction to electromagnetic exploration methodoilandgas24
1. Electromagnetic methods measure the electrical resistivity of the Earth using electromagnetic induction rather than direct contact. This allows data to be collected from moving platforms like helicopters.
2. When EM signals enter the Earth, they can propagate as waves in low conductivity environments or diffuse in higher conductivity environments. Diffusion causes the signal amplitude to decrease exponentially with distance.
3. EM methods work by a transmitter generating a primary oscillating magnetic field that induces currents in conductors, which generate a secondary magnetic field measured by a receiver to obtain information about conductors.
Gravimetry uses measurements of variations in Earth's gravitational field to obtain information about subsurface density variations. It has applications in hydrocarbon exploration, geological mapping, and other fields. Gravity measurements are based on Newton's law of universal gravitation. Instruments used include stable gravimeters like pendulums and torsion balances, as well as portable unstable gravimeters. Measurements require corrections for factors like latitude, altitude, tides and drift. Density differences between rock types are the source of gravitational anomalies that can be interpreted.
2D MASW ANALYSIS FOR GEOTECHNICAL ENGINEERINGAli Osman Öncel
This document describes a study that used seismic refraction and multi-channel analysis of surface waves (MASW) to investigate near-surface shear wave velocities at a site in Egypt. Seismic refraction was used to determine P-wave velocities down to depths of 30 m. MASW was used to determine 1D and 2D shear wave velocity profiles by analyzing Rayleigh surface wave dispersion. Shear wave velocities obtained from MASW were used to evaluate site response and classify the site according to standard site classifications. The study area consists of Quaternary deposits overlying Tertiary sedimentary rocks. P-wave and MASW surveys were conducted along multiple profiles using geophones and a seismograph to
Lithological Investigation at Tombia and Opolo Using Vertical Electrical Soun...IJLT EMAS
Vertical electrical soundings (VES) was carried out in Opolo and Tombia all in Yenagoa local government area, Bayelsa state, Nigeria to understand the resistivity distribution of its subsurface which serves as a tool in investigating subsurface lithology. All VES sounding were stacked together to generate 1D pseudo tomogram and was subsequently interpreted. The interpreted VES curve results shows that Opolo consists of three layers within the depth of investigation. Sandy clay with mixture of silt make up the first layer (Top layer) with resistance value ranging from 24-63Ωm. The second layer is made up of thick clay with very low resistivity values ranging from 3-19Ωm. The third layer is sandyclay with its resistance value ranging from 26-727Ωm.Tombia also reveals that the area is in three layers within the depth of investigation. Sandy clay with a mixture of fine sand made up the first layer (Top soil) with its resistance values ranging from 40-1194Ωm. The second layer is made up of fine sand with resistivity value ranging from 475-5285Ωm. The third layer is made up of sandy clay/sand with its resistance value ranging from 24-28943Ωm.The results of the 1D pseudo tomogram also reveals that Tombia and Opolo consists of three layers within the depth of investigation and pseudo tomograms serves as a basis tool for interpreting lithology and identifying lithological boundaries for the subsurface
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.
This document summarizes an electrical resistivity study conducted around Shika, Kaduna State, Nigeria to map subsurface geology. Vertical electrical sounding was performed at 18 locations using an ABEM terrameter. Resistivity values were interpreted to identify topsoil, weathered basement, fractured basement, and fresh basement layers. Topsoil thickness ranged from 1.06-4.14m with resistivity 60-373 ohm-m. Weathered basement thickness was 1.77-33.04m with resistivity 70-708 ohm-m. Fractured basement extended 12.9-26.3m deep with resistivity 318-834 ohm-m. Fresh basement had resistivity over 1161
The Lectures describes the Electrical method of Geophysical Prospecting in brief. SP surveying and Occurrence of Self potential and its application is discussed in brief.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
1) Vertical electrical sounding using Schlumberger array was conducted at 40 stations to determine subsurface layers and depth to bedrock at the Centre for Energy Research and Training in Zaria, Nigeria.
2) Resistivity values and thickness were derived for three predominant layers - topsoil (2-738 ohm-m thickening 1-3.9m), weathered basement (32-1735 ohm-m thickening 0.52-23m), and fresh basement bedrock (100-6036 ohm-m).
3) Results identified areas suitable for structures and boreholes, and recommended depth of sewage systems to avoid groundwater contamination based on the subsurface resistivity and thickness parameters.
Subsurface 2D Image Analyses of the Uyangha Basement Area, South-Eastern NigeriaIOSR Journals
Geo-electric soundings were made in Stella Maris Secondary School, in Uyangha, Nigeria to image
the subsurface and obtain thicknesses and resistivities of different layers. A quantitative interpretation of the
data obtained clearly reveals the presence of four (4) geo-electric sections which are interpreted to be dry
laterite, moist laterite, weathered basement, and saturated basement. The depth probed is about 100m. The
saturated basement is the aquifer unit. Depth to aquifer unit in the area is at about 65m to 80m.The thickness of
the aquifer unit ranges from 20m to 35m. For ground water exploitation, boreholes in the area should therefore
be drilled to the depth of 91m, for reasonable groundwater yield. The lateritic layer makes the study area
suitable for building construction in the area.
The document describes various geophysical lab equipment used for exploration, including their specifications and applications. It discusses the Terrameter SAS 4000 and Terraloc MK-6 used for resistivity and seismic surveys respectively. Other equipment covered are the shielded antenna GPR for medium resolution surveys, gravimeter for gravity surveys, magnetometer for magnetic surveys, portable well logger for shallow well logging, and Mini-Seis seismograph for blast monitoring and earthquake detection. Each equipment is described along with its specifications, accessories, and uses in applications like mineral, oil and gas exploration, engineering projects, and archaeology.
Seismic methods use seismic waves created by impacts on the surface to map underground structures. The waves travel through underground layers and are reflected or refracted at boundaries between different materials. Analysis of the travel times and velocities of the waves allows determining the depth and type of geological layers. Seismic reflection techniques involve creating waves at shot points and recording them with receivers at different offsets to generate common midpoint gathers. Processing the gathers yields a seismic section that images layer boundaries like an echo sounder. Seismic refraction uses refracted head waves along interfaces to build a shallow velocity model for near-surface layers. Both methods together provide structural and physical characterization of underground features like buried valleys.
This document discusses survey design and procedures for electrical resistivity surveys. It describes three common modes: 1) Sounding mode, where electrode spacing is varied to map resistivity with depth at fixed locations. 2) Profiling mode, where electrode spacing is fixed and the array is moved laterally to map lateral resistivity variations. 3) Profiling-sounding mode, which combines aspects of profiling and sounding modes. Common electrode arrays like Wenner and Schlumberger are described for each mode. Sounding and profiling modes are suited for mapping vertical and horizontal resistivity contrasts respectively.
Geophysical prospecting uses physical methods to study the structure of the Earth's crust and locate minerals and ores. It involves collecting data using geophysical methods like seismic, gravitational, magnetic, electrical, and electromagnetic surveys. Seismic methods are commonly used in exploration. They involve generating seismic waves using sources like sledgehammers and analyzing the reflected and refracted waves detected by receivers to characterize subsurface layers and locate resources based on their elastic properties. Proper data acquisition, processing to reduce noise, and geological interpretation of processed seismic data are required to build an accurate model of the subsurface.
The Use of Geophysics In Ground InvestigationClaire_Graham
The document summarizes the services of Stratascan Ltd, a geophysics survey company. It outlines their history, staff capabilities, the techniques they employ including magnetic surveys, earth resistance, ground penetrating radar and more. It provides examples of archaeological and engineering case studies where different techniques were applied successfully or not.
This document discusses refraction seismology, which is a method used to map geologic structures by analyzing the arrival times of seismic head waves that travel through subsurface layers. It provides definitions and references for further reading on refraction seismology and seismic methods. The document also compares refraction seismology to reflection seismology, noting that refraction uses initial seismic arrivals while reflection analyzes later arriving reflected seismic energy to image subsurface structures and boundaries between layers with different seismic velocities.
This study used electrical resistivity imaging, seismic refraction tomography, and azimuthal resistivity soundings to assess an active open dump site in Kaduna, Nigeria. The objectives were to delineate potential leachate plumes and subsurface pathways that could transport contaminants. Results from resistivity imaging identified low resistivity zones (6-33 ohm-m) representing leachate plumes. Resistivity and seismic models also delineated fractures beneath the weathered basement layer that could act as pathways. Longitudinal conductance values of 0.02-0.1 mhos indicated poor protective capacity, allowing leachate to reach shallow aquifers. Azimuthal resistivity soundings at 45 m depth
Application of Very Low Frequency- Electromagnetic (VLF-EM) Method to Map Fra...theijes
Geophysical survey involving very low frequency electromagnetic technique was applied to investigate possible geologic features like fractured / conductive zones in Auchi and its environs in Edo state, Southwestern Nigeria. The study area is located within latitudes 7o 05’ N.to 7o 10’N. and longitudes 6 o 11’E to 6o 22’E The geologic Formations outcroping in the area are mainly Ajali and Nsukka. Three profiles were taken along the roads from Auchi to Igara, Auchi to Fugar and Auchi to Uloke using Abem Wadi Terrameter. Plots of the profiles were carried out using computer software (Excel) and contouring using Surfer 10 to delineate the fractured/conductive zones. The values range from 0.3 to 22.5 Siemens. Areas of low conductivity values indicate highly massive resistive rocks while Areas of high conductivity indicates the sedimentary terrain/ host rock or mineralized zones. The area is sparsely (few) fractured. Along profile A, two fractured zones were identified with conductivity values of 7.6 to16.8 Siemens between 100m(7.146oN,6.195oE) to 400m (7.150oN, 6.200oE) and 420m to 460m with conductivity value range of 11.0 to 22.5 Siemens. For profile B, one fractured zone was identified and a stretch of massive intrusive from 7.099oN and 7.102oN and 6.357oE to 6.364oE, with conductivity range of 0.9 – 5.2 Siemens at points 400m and 520m – 1000m. Profile C has identifiable fractured zones at 900m – 1100m with conductivity of (35 – 50) Siemens. The intrusive/ host rock conductivity values of (0.3 – 8.7) Siemens located at 380m to 880m 7.156oN and 6.308oE, 1100m to 2000m, 7.148oN and 6.3295oE. A total of five conductive zones were observed.
PIPELINE PLANNING WITH AIRBORNE ELECTROMAGNETICSBrett Johnson
This document summarizes the results of a helicopter electromagnetic survey conducted along a 130km pipeline corridor to map subsurface conductivity and aid in pipeline construction planning. The survey identified areas of shallow bedrock that would require blasting versus deeper overburden that could be trenched. Drill holes along the corridor were used to calibrate the electromagnetic conductivity measurements with actual subsurface conditions. A conductivity value of 6mS/m correlated well with a 2m overburden depth, the depth needed for pipeline trenching. The survey effectively mapped subsurface conditions and reduced costs associated with pipeline planning and construction.
This study estimates local site effects in the Ataköy area of Istanbul, Turkey through multiple techniques. A hybrid 3D finite-difference method is used to model site amplification from a scenario earthquake using a 3D velocity model of the local geology. Horizontal-to-vertical spectral ratios are calculated from microtremor recordings at 30 sites and compared to synthetic noise data from a 1D geological model. The results indicate the strongest amplifications around 1 Hz, with alluvial sites expected to experience amplification factors of 1.5-2. Comparing the different methods provides a comprehensive understanding of site effects in this densely populated and seismically hazardous area of Istanbul.
This document summarizes a study that performed broadband frequency simulations of strong ground motion in the Sea of Marmara region of Turkey based on fault rupture scenarios. Three earthquake scenarios were modeled involving rupture of the Central Marmara Fault and North Boundary Fault, which pose the largest hazard to Istanbul. A hybrid technique was used that combines deterministic and semi-stochastic methods. The location of the hypocenter was found to be a critical parameter for predicting ground motions in Istanbul. Anelasticity was also found to significantly affect regional attenuation of peak ground accelerations. The simulated ground motions resulted in large acceleration response spectra at long periods that could be critical for building damage in Istanbul during an actual earthquake.
The document discusses several types of seismic velocity models including 1D layered models, community velocity models based on direct measurements, unified community models, and 3D tomography models derived from active and passive seismic data. It provides details on numerous global and regional reference models for the crust, mantle, and specific tectonic provinces.
Introduction to electromagnetic exploration methodoilandgas24
1. Electromagnetic methods measure the electrical resistivity of the Earth using electromagnetic induction rather than direct contact. This allows data to be collected from moving platforms like helicopters.
2. When EM signals enter the Earth, they can propagate as waves in low conductivity environments or diffuse in higher conductivity environments. Diffusion causes the signal amplitude to decrease exponentially with distance.
3. EM methods work by a transmitter generating a primary oscillating magnetic field that induces currents in conductors, which generate a secondary magnetic field measured by a receiver to obtain information about conductors.
Gravimetry uses measurements of variations in Earth's gravitational field to obtain information about subsurface density variations. It has applications in hydrocarbon exploration, geological mapping, and other fields. Gravity measurements are based on Newton's law of universal gravitation. Instruments used include stable gravimeters like pendulums and torsion balances, as well as portable unstable gravimeters. Measurements require corrections for factors like latitude, altitude, tides and drift. Density differences between rock types are the source of gravitational anomalies that can be interpreted.
2D MASW ANALYSIS FOR GEOTECHNICAL ENGINEERINGAli Osman Öncel
This document describes a study that used seismic refraction and multi-channel analysis of surface waves (MASW) to investigate near-surface shear wave velocities at a site in Egypt. Seismic refraction was used to determine P-wave velocities down to depths of 30 m. MASW was used to determine 1D and 2D shear wave velocity profiles by analyzing Rayleigh surface wave dispersion. Shear wave velocities obtained from MASW were used to evaluate site response and classify the site according to standard site classifications. The study area consists of Quaternary deposits overlying Tertiary sedimentary rocks. P-wave and MASW surveys were conducted along multiple profiles using geophones and a seismograph to
Lithological Investigation at Tombia and Opolo Using Vertical Electrical Soun...IJLT EMAS
Vertical electrical soundings (VES) was carried out in Opolo and Tombia all in Yenagoa local government area, Bayelsa state, Nigeria to understand the resistivity distribution of its subsurface which serves as a tool in investigating subsurface lithology. All VES sounding were stacked together to generate 1D pseudo tomogram and was subsequently interpreted. The interpreted VES curve results shows that Opolo consists of three layers within the depth of investigation. Sandy clay with mixture of silt make up the first layer (Top layer) with resistance value ranging from 24-63Ωm. The second layer is made up of thick clay with very low resistivity values ranging from 3-19Ωm. The third layer is sandyclay with its resistance value ranging from 26-727Ωm.Tombia also reveals that the area is in three layers within the depth of investigation. Sandy clay with a mixture of fine sand made up the first layer (Top soil) with its resistance values ranging from 40-1194Ωm. The second layer is made up of fine sand with resistivity value ranging from 475-5285Ωm. The third layer is made up of sandy clay/sand with its resistance value ranging from 24-28943Ωm.The results of the 1D pseudo tomogram also reveals that Tombia and Opolo consists of three layers within the depth of investigation and pseudo tomograms serves as a basis tool for interpreting lithology and identifying lithological boundaries for the subsurface
Geophysical studies on Dahab area, South Sinai. Egyptosamaabdelraouf1
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TWO DIMENSIONAL ELECTRICAL RESISTIVITY IMAGING SURVEY FOR LITHOSTRATIGRAPHIC....Onahikechukwu1
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This document summarizes a study that used vertical electrical sounding to determine the average thickness of the aquifer in Abakaliki, Nigeria. Three locations were surveyed and the resistivity curves generated showed 5 geoelectrical layers at each location. The layers had average thicknesses ranging from 2.38m to 28.86m. The fourth layer, interpreted as likely wet and fractured shales, was identified as the aquifer. Its average thickness across the three locations was estimated to be 28.86m. Therefore, the thickness of the aquifer in the study area was determined to be approximately 29m.
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2) Aeromagnetic data was collected and processed using various techniques including filtering, inversion, and enhancement to generate a model of the subsurface basement topography and interpret the geology.
3) Maps produced from the processed aeromagnetic data revealed the basement topography, structural lineaments and their orientations, and estimated depths to magnetic sources in the study area.
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1. This document describes a field laboratory activity using geophysical methods for civil engineering site investigations. The goal is to build competency in preliminary site assessment.
2. Two geophysical methods are used: resistivity and seismic refraction. Resistivity involves passing electrical currents through the ground to determine subsurface resistivity. Seismic refraction uses the travel time of seismic waves to determine subsurface layer velocities.
3. The equipment, layout, and processing software for each method is described. The laboratory report will interpret materials based on velocity, discuss rippability, determine the water table, and identify structural geology features.
Hydrogeological Application of Refraction Seismicsiosrjce
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The document discusses ambient noise correlation techniques to study seismic velocity structures. It analyzes continuous seismic data recorded by 11 stations in the Koyna-Warna region of India. Cross-correlating ambient noise between station pairs and extracting surface wave dispersion data allows constructing 1D shear velocity models along each path. The models show a 0.8 km thick Deccan trap layer with a velocity of 3 km/s underlain by a 3.3 km/s weathered granite layer and a deeper 3.6 km/s granite-gneiss basement. Ambient noise techniques provide useful seismic information even in aseismic zones.
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This document discusses seismic reflection methods and their application to shallow subsurface exploration problems. It provides an overview of seismic reflection fundamentals, including how reflections are generated at acoustic impedance contrasts and how common depth point (CDP) processing works to enhance reflection signals. The document also discusses data acquisition parameters and challenges of shallow seismic reflection, and gives examples of applications such as mapping geologic layers, faults, and cavities.
This document summarizes research using deep seismic sounding by microtremor (SSMT) broadband signals to study the Vrancea seismic zone in Romania. The SSMT methodology analyzes spatial variations in microseismic noise spectra to image subsurface structures. Results show a low-velocity seismic boundary in the focal zone from 170-280km depth. High-velocity structures west and east of the zone may represent the Intra-Carpathian subplate and Moessian platform. Hypocenters localized in intermediate velocities between the low-velocity zone below and high-velocity structures at sides. Comparisons support findings. Repeated experiments yielded consistent results, validating the SSMT method.
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Engineering geophysical study of unconsolidated top soil using shallow seismic refraction and electrical resistivity techniques
1. Journal of Environment and Earth Science www.iiste.org
ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online)
Vol. 3, No.8, 2013
120
Engineering Geophysical Study of Unconsolidated Top Soil Using
Shallow Seismic Refraction and Electrical Resistivity Techniques
Muhammad Younis Khan
National Centre of Excellence in Geology University of Peshawar, Pakistan
E-mail: quaidian2007@gmail.com
Abstract
A near-surface geophysical study was conducted at University of Peshawar (UOP), Khyber Pakhtunkhwa,
Pakistan, using an integrated approach including seismic refraction and electrical resistivity survey (ERS)
techniques in order to image the shallow subsurface in terms of main geological and geophysical properties
covering the study area. Seismic longitudinal wave velocities (Vp) were determined within four meters beneath
ground surface which indirectly provided us with critical subsurface information about depth of layers,
morphology and stratigraphic sequence without borehole information. The results of the seismic refraction
survey along profile AB, showed two-layers separated by a refractor having gentle slope and P-wave velocity
values (223m/sec & 316 m/sec) for overlying and underlying layers respectively indicating loose soil filled in
top four meters underneath the surveyed seismic profile. Seismic refraction data demonstrated shallow
subsurface structure characterized by longitudinal wave velocities less than 330 m/s.Apparant resistivity data
was acquired along two profiles (CD & DE) using four shlumberger vertical electrical soundings with maximum
spread length of 10m. Electrical resistivity survey validated the results obtained from seismic refraction data
analysis by detecting bi-layer near-surface geologic model at all VES stations with distinct characteristics. These
geoelectric layers included top soil/dry unconsolidated surface material ranging in thickness from 1.11m to 1.3m
with true resistivity values (38.08 - 52.70 Ωm) and less resistive (13.13-18.38 Ωm) clayey layer. Integrated
geophysical approach showed that overburden terrain in the target zone is characterized by a relatively thin
superficial layer (dry unconsolidated sediments) underlain by a clay layer having high porosity and saturation.
Based on seismic velocities (223m/sec & 316 m/sec) and resistivity values (13.13 - 52.70 Ωm), it is derived that
sub surface soil conditions within studied depth interval are poor and should be considered seriously as this may
put the high rise buildings at risk.
Keywords: Shallow seismic refraction, Compressional wave velocity (Vp), time-term inversion, electrical
resistivity survey (ERS), top soil.
1. Introduction
Seismic refraction method is one of the best tool for investigation of ground water, bedrock mapping, type and
associated changes (lateral and vertical) in lithology. The compressional P-waves can be used to detect the
cavities and resolve many other problems in shallow subsurface. Seismic refraction technique is also
successfully used for several engineering problems such as dam sites as well as determination of the physical
characteristics of ground, investigation of the deep earth layers and for geotechnical purposes ,demonstrated by
(Tezcan et al., 2006; Budhu &Al-Karni 1993; Othman 2005; Dormieux & Pecker 1995.,Richards et al., 1993;
Turker 2004; Paolucci & Pecker 1997).Seismic refraction method is used to study the physical properties of site
presented by (Dutta 1984; Hatherly & Neville 1986).Several studies demonstrated that longitudinal velocity is
less than 330 m/s in shallow sub-surface e.g. low compressional velocities were discussed quantitatively by
Bachrach & Nur 1998. Similarly Bachrach et al. (1998) found low longitudinal wave velocity (<100 m/s) of
beach sand. Baker et al. (1999) showed that compressional (P) wave velocities in the shallow sub-surface are
lower than the velocity in the air.
Shallow electrical resistivity technique is used to address the geological ,hydro-geological and environmental
problems. Some recent studies focused on the delineation of the geometry of the uppermost layers of shallow
sub-surface (Lamotte et al. 1994; Robain et al. 1995, 1996).
2. Materials & Methods
The study was accomplished for each geophysical method, following the three steps given below
2.1 Data Acquisition/Field operations
Field study was performed at campus of university of Peshawar,Khyber pakhtunkhwa, Pakistan located between
Latitudes 33˚56’0” N - 34˚40’0” N and Longitudes 71˚27’0” E - 71˚33’0” E (fig.1). In seismic-profiling method
a seismic source and geophones planted at regular intervals across the ground surface is used for data acquisition
(Beck 1981; Reynolds 1997; Sharma 1997). For seismic refraction data acquisition, profile-shooting technique is
used to acquire the data which consists of all the common seismic refraction survey modes in a single profile.
The refraction work was based on measuring the travel time of longitudinal wave passed through the subsurface,
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generated by striking sledge hammer of 7kg on aluminum plate as a source of seismic energy, refracted from an
interface and detected via vertical component geophones (10 Hz) spaced at 1m interval on the surface. All these
geophones are connected through seismic cable to a 24-channel Geometrics digital seismograph
(Geode).Specific geophysical survey geometry is used based on five shots in appropriate fashion along the
spread. At minimum there should be two shots located at either end of the seismic line. We planted the very first
geophone at 0-m along the seismic line. First shot is fired at distance of 0.5m in start of seismic line before
geophone (G1), the second one located at a 5.75 m, third at 11.5 m ,the fourth shot at a 17.25 m, and the last shot
is at 23.5 m along profile AB while going from 0m towards end of spread length (23m) as shown in (fig.2). The
total spread length of seismic refraction profile is 23 m containing an array of 24 geophones spaced evenly at 1
m. This specific physical layout of geophones and shots provides better coverage to generate an interpretable
stacked profile.
Shallow electrical resistivity data is acquired along two resistivity profiles along profiles (CD & DE) based on
four vertical electrical soundings using Shlumberger configuration. ABEM Terrameter (SAS 1000/4000) is used
to for apparent resistivity readings on plain area with maximum electrode separation of 10m for each traverse in
order to clearly image the target at very shallow depth within top four meters zone from ground surface. The
primary acquisition parameters for both methods are given in table 1.
2.2 Data processing
Seismic refraction data is always processed to enhance the data quality by suppressing noises from different
sources to generate final velocity model. The recorded seismic data saved in laptop PC were imported to one of
the module (Pickwin95) of commercial software package, seisImager.All traces were normalized and clipped.
Also some bad records were killed in order to extract meaningful information. Finally first breaks were carefully
picked using Pickwin. The picked first-arrival time data were uploaded to another module (Plotrefa).Thereinafter
inversion method (time-term inversion) was used to get the velocity structure (fig.6) with root mean square
(RMS) error of 1.5%.
ERS data (apparent resistivity) obtained from each station was uploaded to ipiwin2 software and plotted against
electrode spacing (AB/2) on double logarithmic scale to get the VES sounding curves. The sounding curves,
models and their respective geoelectric sections are prepared for each profile (fig.4 & 5).
2.3 Interpretation/Conclusions
There are different techniques in use for refraction data analysis and interpretation e.g. ray-tracing method
(Whiteley 2002, 2004), delay-time method (Wyrobek 1956; Palmer 1980; Sjogren 2000).Some other scientists
(Hales 1958; Barton & Barker 2003) discussed the intercept−time method. Recently researchers have focused on
inversion and tomography method (Zhang & Toksöz 1998;Watanabe et al. 1999; Hecht 2003).
There is no subsurface ground model available about the thickness, depth, velocity distribution in the top soil and
weathering layer in the surveyed area. The Main purpose of the study was to determine shallow sub-surface
structure using shallow seismic refraction method and its confirmation by another surface geophysical tool
(ERS). Keeping in mind the objective, receiver interval of only 1m in case of refraction and maximum resistivity
profile length of 10m was chosen during data acquisition to get the improved subsurface image. Although the
delineated geologic strata has small variations in terms of geophysical properties like P-wave velocities and
electrical resistivities but are being mapped in this research work because of special geophysical configurations.
An integrated geophysical approach including electrical resistivity and seismic refraction is used to delineate
shallow sub-surface. Each method responds to different geophysical property with varying resolution however
interpreted results in both cases can be combined and correlated to get comprehensive geological information for
site under investigation.
First compressional wave velocity (Vp) –depth model is derived from time-distance (T-D) plots after assigning
layers by employing two-layer model to represent the shallow subsurface structure on the studied area. Taking
the seismic profile AB, for example two layers are observed. A thin layer of loose sediments is noticed
corresponding to the first arrivals (direct waves close to the seismic energy source) marking the superficial layer
with very low velocity (223 m/sec) and thickness (0.2 to 1.7 m) approximately along the seismic line. The first
layer is thinner on margins of the profile AB while gets thicker relatively in central part. Low acoustic
impedance contrast and an undulating trend are shown by the contact between layers. Difference is observed in
depth of the refractor along the seismic line. In general the refractor is gently dipping in study area. The deepest
layer (layer2) in the geo-seismic section is appeared at depth of 1.7m exactly below the midpoint (11.5 m) of
seismic profile, characterized by comparatively high P-wave velocity (316 m/sec).
A resistivity survey was also conducted on warm and sunny day of May 14, 2013. The ERS data results are
displayed in form of table 2 and corresponding resistivity - cross sections under depth sounding curves (fig.4 &
5), which confirmed the two layer geologic structure. Interpretation of both resistivity lines showed the
heterogeneous nature of studied part of vadose zone. For example; location 1 consists of two layers with
resistivity values of 18.40 Ωm &13.13 Ωm while location 2 is characterized by 19.50 Ωm & 15.0 Ωm for first
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and second layer respectively. First layer is more thicker (1.28m) and deeper at location1 than at location 2
where its thickness is 1.11m.VES curves of Location 3 showed the same sub-surface geologic sequence having
resistivity values (52.70 Ωm & 20.72 Ωm) for overlying and underlying geologic layers respectively. At
Location 4 top most geo-electric layer has 38.08 Ωm resistivity while lower layer is characterized by 18.38
Ωm.It is deduced from the interpreted sounding curves of location 3 & 4 that first geologic layer is 1.259m &
1.059m thick respectively. Here both stations have almost same thickness value of layer 1.
Both types of geophysical traverses revealed approximately same thickness of first layer and depth of interface
appeared across the studied site but low resistivity contrast is observed along profile line CD as compared to
profile EF.
It is concluded that top overburden material within four meters is divided in two sub-layers, a superficial layer
composed of unconsolidated sediments with high resistivity because of dry nature underlain by a thicker, slightly
compact but more conductive indicating relatively high moisture content and clay component concentrated in
this part of geological model.
There is good correlation between seismic refraction and electrical resistivity as both methods mapped the same
stratigraphic sequence with the equal number of layers but a depth variation still detected, due to the different
physical properties measured by the two geophysical tools ,employed while field operations. From resistivity
cross sections it is clear that an interface is appeared at 1.28 m from the surface. On average an interface is
appeared slightly below 1m along depth axis on resistivity cross section as well as in case of velocity structure.
It is deduced from the interpretation of geophysical data (seismic refraction & ERS ),that the subsurface
geologic sequence beneath the study area up to 4m depth is composed of material having clayey sand content
with high porosity and high degree of saturation which are indications of poor sub-soil conditions due to its low
load-bearing capacity. In geotechnical applications all these factors are of great importance which must be taken
into account seriously during construction of massive engineering structures.
Joint interpretation of both types of data provided us with more accurate geotechnical model with high
confidence where both methods seem to be in good agreement and areas of some doubtful information, which
could then be confirmed via drilling as several feet’s uncertainty in depth of interface is of great importance in
very near sub-surface studies. Combined geophysical approach helped us in making the interpretation easier by
adding to spatial resolution than separate approach traditionally used in engineering and hydrogeology.
In future the study will be extended to weathering layer by an integrated geophysical approach using both the
seismic refraction and electrical resistivity techniques with new physical layouts for greater depth of penetration.
Also geophysical properties will be correlated with geotechnical parameters in order to better understand the
sub-soil conditions.
Acknowledgement
I express my sincere gratitude towards Mr.Liaqat Ali , Khalid Latif Kaif and Dr.Fazal Rahim for their valuable
guidance in the research work. I am also very thankful to Professor Dr.M.Asif Khan, Director, National Centre
of Excellence in Geology University of Peshawar, Pakistan for his consistent encouragement and providing all
the research facilities in the centre for the geophysical investigations.
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Muhammad Younis Khan born in Lakki Marwat (Khyber Pakhtunkhwa), Pakistan. He earned his M.sc
and M.Phil degree in geophysics in 2009 and 2011 respectively, from Quaid-i-Azam university
Islamabad,Pakistan.His fields of interest include hydrogeophysics/applied geophysics and petrophysics.
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Fig 1: Map showing location of study area and layout for ERS (CD & EF) & seismic refraction (AB) profiles
Fig 2: Seismic refraction profile AB, arrows highlighted in red are indicating shot points
Table 1: Summary of geophysical acquisition parameters
Acquisition parameters for seismic refraction data
Recording system Geode (24-channel seismograph)
Source Sledgehammer 7 kg
Sampling interval 0.125 ms
Record length 256 ms
Geophones 10 Hz (vertical)
Recording format SEG-2
Geophone interval 1 m
Acquisition parameters for electrical resistivity data
Recording system ABEM Terrameter (SAS 1000/4000)
Configuration type Shlumberger
Mode of survey VES (vertical electrical sounding)
Maximum electrode separation 10m
Profile interval 20m
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Table 2: Summary of the interpreted VES curves
# VES /Location N (# layers) ρ (Ωm) h (m) d (m)
1 2 1 18.40 1.28 1.28
2 13.13 - -
2 2 1 19.50 1.11 1.11
2 15.00 - -
3 2 1 52.70 1.059 1.059
2 20.72 - -
4 2 1 38.08 1.259 1.259
2 18.38 - -
0 2 4 6 8 10 12 14 16 18 20 22 24 26
T
i
m
e
(m
s
e
c
)
0
40
80
120
160
200
Distance (m)
Source= 0.0m
819.dat
0 2 4 6 8 10 12 14 16 18 20 22 24 26
T
i
m
e
(m
s
e
c
)
0
40
80
120
160
200
Distance (m)
Source= 5.8m
816.dat
A-Normal shooting at 0.0 m B-Shooting at 5.75m between G6 &G7
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Tim
e
(m
sec)
0
40
80
120
160
200
Distance (m)
Source= 11.5m
811.dat
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Tim
e
(msec)
0
40
80
120
160
200
Distance (m)
Source= 18.3m
809.dat
C-Mid-point Shooting at 11.5 m D-Shooting at 18.25 m between G18& G19C-Mid-point
0 2 4 6 8 1
0 12 14 1
6 1
8 2
0 2
2 2
4 2
6
Time
(msec)
0
40
80
1
20
1
60
2
00
Distance (m)
Source= 23.0m
806.dat
E-Reverse shooting at 23.0 m
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Figure 3: Seismograms with picked primary arrivals at study area along traverse AB
VES 1 VES 4
Figure 4: Interpreted VES curves & Resistivity cross section underneath VES1 & VES 2.
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Figure 5: Interpreted VES curves & Resistivity cross section underneath VES3 & VES 4.
Figure 6: Time-distance (T-D) plot and Velocity-depth model of profile AB.
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