SEG International Conf.on Engineering Geophysics Part Two

SEG International Conf.on Engineering Geophysics Part Two

Postby salsinawi » Sun Sep 04, 2016 4:34 pm



International Conference on Engineering Geophysics, Part wo
Al Ain, United Arab Emirates, 15-18 November 2015
SEG Global Meeting Abstracts




Exploring the Egyptian Alabaster at the Western Eocene Plateau of Assiut City, Egypt, using ground penetrating radar

Authors: Reem H. Sayed*, Gamal Z. Abdel Aal, Mohamed O. Ibrahim, Hassan A. Soliman
Geology Department, Faculty of Science, Assiut University, Assiut, 71516, Egypt;
Authors: Anna A. Klochko, Dmitry Shishkov
Geology Department, Lomonosov Moscow State University, Moscow, Russia
Ground penetrating radar (GPR) is one of the principal geophysical imaging tools for near-surface investigations of physical properties and structure. Georadar survey was conducted in the vicinity of excavated Egyptian alabaster quarry at the western Eocene plateau of Assiut city, Egypt. The main objective of this study was to explore the extend and depth of the alabaster veins and the associated subsurface features (e.g., fractures and cavities). The surface of the study site is absolutely smooth and covered by sandy-gravel layer of Aeolian alluvium origin overlain the Eocene limestone. Several profiles were surveyed using the SIR-3000 GSSI GPR unit and the 200 MHz antenna mounted behind a vehicle. Radan software has been used to process the GPR data and several anomalies were identified. The 2D Georadar sections showed volumetric anomalies with an extremely intensive high amplitude reflection resulting from the alabaster bodies that are associated with different set of fractures and cavities occurred at depth ranges from 2 to 4 meter below the ground surface. A two-layer structure is reconstructed in 3D site simulation. The upper layer of the cross-section represents the fractured limestone up to depth about 3.5 m and characterized by clear and slightly sloping axes of synchronism phase, broken in some spots by area of finely disordered reflections. At depth greater than 4 m, a large branching out body (or group of bodies), creating intensive reflections is determined. It is clear that the results of this study are very promising and a detailed geophysical survey is required that will increase the potentiality of carrying out quarrying and extraction activities of the alabaster bodies at the study area.

Keynote Speech: Applications of Engineering Seismology in Urban Areas

Authors: Oz Yilmaz
Anatolian Geophysical
I present two case studies which describe applications of engineering seismology in urban areas (Yilmaz, 2013):
1. (1) High-resolution shallow offshore 3-D seismic survey for the Bosphorus Subsea Road Tunnel Project, and
2. (2) Seismic, geotechnical, and earthquake engineering site characterization for a residential project in Istanbul.
In Case Study 1, we conducted a 3-D high-resolution shallow seismic survey in 2011 to confirm the geometry of the future Bosphorus Subsea Road Tunnel traverse. We processed the data to obtain 3-D PSTM and PSDM volumes, and interpreted these image volumes and correlated the interpretation results with the offshore borehole data. With the recoverable signal band of 30-960 Hz, we attained a vertical resolution of less than 1 m. The image volume from 3-D PSTM exhibits the presence of an erosional channel associated with a Palaeo-Bosphorus waterway. The eastern (Asian side) slope of the channel can be delineated in many of the inline sections. Nevertheless, the western slope (European side) can only be faintly inferred from some of the inline sections. The reason is that the western slope is occupied by a zone of highly weathered Trakya bedrock debris with weak impedance contrast with the soil column above and within the channel. Prior to the flooding of the erosional channel by the Palaeo-Bosphorus, the river bed consisted of gravel. There are no faults that can be traced within the seismic image volume with potential capability to generate an earthquake of a magnitude (>6) that would be of concern in the tunnel design. The planned tunnel traverse is within the Trakya Formation except for a middle segment, 806 m in length, within the soil column composed of interbedded sand-clay-silt deposits with varying percentages of fines content.
In Case Study 2, we determined the seismic model of the soil column within a residential project site in Istanbul. To accomplish this, we conducted shallow seismic surveys at 20 locations and estimated the P-and S-wave velocity-depth profiles down to a depth of 30 m. We then combined the seismic velocities with the geotechnical borehole information regarding the lithology of the soil column and determined the site-specific geotechnical earthquake engineering parameters. Specifically, we computed the maximum soil amplification ratio, maximum surface-bedrock acceleration ratio, depth interval of significant acceleration, maximum soil-rock response ratio, and design spectrum periods TA-TB. Additionally, we conducted shallow reflection seismic and resistivity surveys to delineate the geometry of landslide surfaces with potential susceptibility to failure.

• Hazard assessment and site characterization at an oil and gas well site using surface wave methods

Authors: Steven D. Sloan*, J. Tyler Schwenk, Robert H. Stevens, Benjamin W. Butler
XRI Geophysics
Surface wave methods were used to interrogate the subsurface along a proposed natural gas pipeline route to identify potential subsurface hazards prior to construction and around existing sinkholes to determine their lateral extent beyond the surface expression at an oil and gas production facility. Shear-wave velocity cross-sections derived using the multichannel analysis of surface waves method along the pipeline route were used to identify low-velocity areas that might be indicative of voids or structurally weaker zones and to select geotechnical boring locations for a subsequent geotechnical engineering assessment. Small sinkholes are known to exist and develop in the study area and their formation beneath or around pipelines is an immediate threat to public and environmental safety. Potential sinkholes in the immediate area of the well site also pose a threat to personnel, equipment, and infrastructure if not identified before collapsing at the surface. Survey results identified several anomalous zones along the proposed pipeline route to further analyze during the geotechnical assessment. Two sinkholes that have breached the surface were also shown to be larger in extent beneath the ground surface than the surface expression would suggest.


Probabilistic Vulnerability Assessment of the Building Inventory in an Extended Seismically Active Area in the UAE

Authors: Aman Mwafy*, Abdelrahman Ashri, Anas Issa
Civil and Environmental Engineering Department, United Arab Emirates University, UAE.
The main outcomes of recent research projects that were devoted to the probabilistic vulnerability assessment of the modern and pre-code building inventory in an earthquake-prone area in the UAE are briefly presented in this paper. The selection and design approaches of a wide range of structures to represent the study area with varying building heights, lateral force resisting systems and construction dates are discussed. The idealization approach of the reference buildings for dynamic response simulations using a detailed modeling approach as well as the selection of forty natural earthquake records to represent the seismotectonic setting of the study area are presented. The development of a wide range of three-dimensional simulation-based fragility relationships for the building inventory in the UAE using thousands of inelastic dynamic analyses is introduced. Examples demonstrating the possible impacts of different seismic scenarios on the built environment using the developed fragility functions are finally discussed. While the focus of the presented research projects was on the reliable assessment of physical damage in a seismically active area in the UAE, the outcomes represent the main driving engine for the development of a state of the art loss estimation and hazard mitigation system for the region.


GPR study of karst in a carbonate coastal area for evaluating its suitability for construction, Wadi Shab, Eastern Oman

Authors: Hesham El-Kaliouby*
Sultan Qaboos University, Earth Science Dept., Oman, and National Research Center, Geophysics Dept., Egypt
Ground Penetrating Radar survey was conducted for the detection of fractures and cavities in the carbonate section at two sites along the coast line in Wadi Shab, Eastern Oman. The survey objective is to determine the location and size of cavities or sinkholes that may cause collapse of buildings of residential area and to assess the suitability of another area for construction and living on it. Two antennas with different central frequency (270MHz and 400MHz) have been used to investigate different depths and resolutions. Results showed a number of hyperbolas that disturbed the continuity of the GPR signals indicating the presence of fracture zones and cavities within the limestone. The GPR waves could not penetrate more than 2-5m depth at the surveyed areas, which could be related to attenuation caused by clays and sea water saturated limestone through fractures filling the limestone secondary pores. Results not only informed of existing subsurface cavities, but also warn of potentially hazardous situation enabling city planners, and civil engineers to take proper precautions before any undesirable situation arise.

Geophysical Study of the mechanism of sinkhole formation in north-east Algeria

Authors: F. Khaldaoui, M. Djeddi*
Laboratoire de Géophysique;
Authors: Y. Djediat
Laboratoire de Géodynamique FSTGAT-Université des Sciences et de la Technologie Houari Boumediene;
Authors: A. Ydri
Laboratoire de Géophysique
The sinkholes are cavities in the ground under whose existence is favored by the dissolution of carbonate rocks. These structures are created by unforeseen events and appear on the surface by collapsing. Carbonate rocks, sensitive karst dissolution, depend on the instability of the geodynamic process which continues to the soil surface.
In the case of presence of the sinkhole, it is important to delineate risk areas in order to define a perimeter of protection for the water resource and geotechnical work.
In this objective a collapse takes place in February 2015 at El Ouldja (North-East of Algeria), a geophysical surveys, including 2D electrical resistivity imaging and electromagnetic induction method (EM31), were employed in the early stages after the initial collapse to determine the risk areas and collapsed features in depth. The work took place on April 2015.

Strong motion source model for the 2003 Boumerdes, Algeria, earthquake


Authors: Faouzi Gheroudj*
CGS, National Center of Applied Research in Earthquake Engineering, Rue Kaddour Rahim, Hussein Dey, B.P. 252, Algiers, Algeria;
Authors: Hiroe Miyake
Earthquake Research Institute, University of Tokyo, Tokyo, Japan;
Authors: Toshiaki Yokoi
International Institute of Seismology and Earthquake Engineering / Building Research Institute, Tsukuba, Japan;
Authors: Nasser Laouami

CGS, National Center of Applied Research in Earthquake Engineering, 1 Rue Kaddour Rahim, Hussein Dey, B.P. 252, Algiers, Algeria
The 2003 Mw 6.8 Boumerdes earthquake caused serious damage to Boumerdes prefecture and the northeast part of Algiers. The strong motions were recorded at several seismic stations by the national accelerometer network. In this study, we have applied empirical Green’s function method formulated by Irikura (1986) and Irikura & Kamae (1994) to the 2003 Boumerdes earthquake to determine the strong motion source model that best reproduces near fault records in the 0.2-10 Hz frequency band.
The best source model was obtained by fitting the synthetic accelerations, velocities, and displacement waveforms to the observed ones. Seismic wave propagation and site amplification effects on the strong ground motion are explicitly taken into account considering the aftershocks recorded at same stations as empirical Green’s functions. The source models defined in this study was compared to the scaling laws in terms of rupture area, strong motions generation area


Strong motion source model for the 2003 Boumerdes, Algeria, earthquake
Authors: Faouzi Gheroudj*
CGS, National Center of Applied Research in Earthquake Engineering, Rue Kaddour Rahim, Hussein Dey, B.P. 252, Algiers, Algeria;
Authors: Hiroe Miyake
Earthquake Research Institute, University of Tokyo, Tokyo, Japan;
Authors: Toshiaki Yokoi
International Institute of Seismology and Earthquake Engineering / Building Research Institute, Tsukuba, Japan;
Authors: Nasser Laouami
CGS, National Center of Applied Research in Earthquake Engineering, 1 Rue Kaddour Rahim, Hussein Dey, B.P. 252, Algiers, Algeria
The 2003 Mw 6.8 Boumerdes earthquake caused serious damage to Boumerdes prefecture and the northeast part of Algiers. The strong motions were recorded at several seismic stations by the national accelerometer network. In this study, we have applied empirical Green’s function method formulated by Irikura (1986) and Irikura & Kamae (1994) to the 2003 Boumerdes earthquake to determine the strong motion source model that best reproduces near fault records in the 0.2-10 Hz frequency band.
The best source model was obtained by fitting the synthetic accelerations, velocities, and displacement waveforms to the observed ones. Seismic wave propagation and site amplification effects on the strong ground motion are explicitly taken into account considering the aftershocks recorded at same stations as empirical Green’s functions. The source models defined in this study was compared to the scaling laws in terms of rupture area, strong motions generation area and rise time. It shows good agreements with the other source models for crustal earthquakes.


Water level variations and earthquakes in the Lake Van Area, Eastern Turkey
Authors: Murat Utkucu*
Sakarya University, Engineering Faculty, Department of Geophysics, Serdivan, 54187 Sakarya, Turkey;
Authors: Hasan Arman
United Arab Emirates University, College of Science, Department of Geology, Al Ain, United Arab Emirates
The Lake Van area has been a seismically active region as indicated by historical and instrumental seismicity studies and exemplified by the recent occurrence of the devastating 23 October 2011 Van earthquake (MW 7.1). The present study is mainly focus on the seismicity of the area after 1000 AD. The seismicity is compiled from several historical sources, historical seismicity studies and the existing seismicity catalogues. The impact of the large earthquakes and possible source faults are discussed. The seismicity is then compared with the existing water level change reports of the Lake Van for further discussing of the interaction of the earthquakes with the other natural phenomena at work and earthquake hazard in the future.



Detection of subsurface karstic features using electrical resistivity tomography, case study, Al Ain, United Arab Emirates

Authors: Tanzeel Ur Rehman Sabir*, Mahmoud K. Harb, Emad Sharif, Mohd. J. Ahmed
Arab Center for Engineering Studies, Dubai, UAE
Subsurface karstic features are one of the major concerns for the construction sector in United Arab Emirates. Subsurface cavities form an important hazard at Al-Ain city and the suburbs. These cavities have led to ground subsidence eventually leading to damages to infrastructures like buildings, (Shaika Salam Mosque at the center of the Al-Ain city is glaring example) such as sagging and cracking of road surfaces at several locations. This has led to acquiring geophysical information during site investigations which have become a mandatory requirement for the construction projects within AlAin Municipality. These investigations aid in detection and mapping of weak zones, Karst and solution features, further utilized for hazard and risk assessments of the survey area. The interpretation of ERT-2D data shows the existence of several subsurface open and sediment in-filled cavities and zones of weakness in rocks, particularly above the ground water table within the limestone layers. Correlation between ERT results and ground materials are established to prepare risk maps, which identifies high and low risk areas within the site based on specific criteria, which includes resistivity anomaly distribution, results of verification boreholes, structural load and footing design.
Seismic Scenario-Structure-Based Performance Criteria for RC High-rise Wall Buildings

Authors: Wael Alwaeli*
Department of Civil and Structural Engineering, The University of Sheffield, UK;
Authors: Aman Mwafy
Civil and Environmental Engineering Department, United Arab Emirates University, UAE;
Authors: Kypros Pilakoutas, Maurizio Guadagnini
Department of Civil and Structural Engineering, The University of Sheffield, UK
The number of RC high-rise buildings is rapidly growing in multiple-scenario earthquake-prone regions around the World as a result of several social and economic considerations. The seismic vulnerability of this category of structures to different earthquake scenarios is poorly understood and proper quantitative limit state criteria to different performance levels are lacking. Motivated by the pressing need to derive more reliable fragility relations to be used in earthquake lose assessments, a methodology is proposed to obtain a new, Seismic Scenario-Structure-Based (SSSB) definition of limit state criteria for RC high-rise wall buildings. A 30-story wall building is utilized to illustrate the methodology. The building is located in Dubai (UAE); a city vulnerable to sever distant earthquakes alongside moderate near-field events therefore selected as a study region in the present study. Multi-Record Incremental Dynamic Analyses (MRIDAs) are conducted to map building local response at different seismic intensities and link it to the global response through a reliable proposed Damage Measure (DM). The study concludes with proposing new, SSSB limit state criteria for the sample building. The proposed methodology and limit state criteria are applicable to a wide range of RC high-rise buildings and seismic regions comparable to those investigated in the current study.
Recent technologies for near surface imaging in the Arabian Peninsula

Authors: A. Vesnaver*, Y. Bouzidi, L. Hou
Petroleum Institute, Abu Dhabi, United Arab Emirates
Compensating for near surface signal distortions is an evergreen challenge for land seismic imaging in the Arabian Peninsula. Techniques exist that may solve local problems, as high-resolution dedicated surveys, but they are not economically viable at a regional level. In this paper, we review a few recent technologies that contribute to mitigate the near surface challenges with a limited impact to the acquisition budget.

Impacts of hydraulic fracturing on the environment and on human health

Authors: Mohamed Djeddi
USTHB, Faculté des sciences de la terre géographie et aménagement du territoire, Laboratoire de Géophysique, Algérie
Shale gas and shale oil extraction is currently a hot topic in Europe and recently in North Africa, not only for the potential effects on the environment. Further questions raised relate to the role, if any, these energy carriers can play in the low-carbon economy model towards which the countries intend to shift and their relevance to decrease the dependence on imported energy commodities.
This contribution examines the Impacts of hydraulic fracturing on the environment and on human health. Quantitative and qualitative data impacts are taken from the US experience at the time this method in Europe is in its infancy, while the US has more than 40 years of experience and already drilled over 50 000 wells. Shale gas (GoS) had (especially the US) a boom during the last decade thanks to hydraulic fracturing horizontal drilling that extracts the gas dissolved in the rock at 2 or 3 km deep. This technique requires very high injection pressure of a liquid composed of water (in large quantities), sand and chemicals whose composition varies according to the firms, the rock and the depth of the wells. A portion of this liquid (25 to 50%) occurred and must be stored in surface impoundments before being processed.
Geotechnical investigation of Namar dam site using geophysical tools, Riyadh area, Saudi Arabia

ERT, GPR, tomography
Authors: Abdullah H. Alhaj*, Hussam AL-mudhi
Geology and Geophysics Department, King Saud University, Saudi Arabia
Based on the expected hazards that threaten the existing dams in Riyadh area due to Collapse of dams or leakages across them. As a result of defective structure and cavities, the proposed research will employ different geophysical technique on Wadi Namar Dam site which are often the most cost-effective and rapid means. Electric Resistivity Tomography (ERT), Seismic Refraction Tomography (SRT) and GPR techniques will be used for mapping bedrock topography, identifying near-surface karstic sinkholes or cavities and regions of potential weakness (e.g., faults and fracture) in the study site Figure 1.
Workflows for characterization of Shale gas
Authors: Afrah Khalid Ahmed Siddique*
NED University of Engineering & Technology
Seismic method plays great role in all aspects of shale-gas-plays starting from identification of promising shales, describing reservoir characteristics (net-to-gross porosity, saturation, fracture, brittleness, etc), optimizing drilling, stimulation & enhancing production. As shale gas resources have emerged as a viable energy source, their characterization has gained significance. However to characterize the shale gas different geophysical workflows are used on 3D surface seismic data and by integrating seismic attributes & logs, source rocks and reservoir properties within shale can be mapped away from the well.We discuss some of these workflows below using well log data and seismic data.
Engineering Geophysics: Human Activities and Humanitarian Applications

Authors: Koya Suto
Terra Australis Geophysica Pty Ltd, Brisbane, Australia
This paper presents an outline of three projects the author is involved for improvement of human living condition: creating better life and recovering from disasters, in particular. Solomon Islands are a Pacific Republic where fossil fuel resource is scarce. A hydroelectric dam project is planned and a seismic survey was conducted across a river as a part of feasibility study. The result led to proceeding construction of the dam. The second project shows a case history of an MASW survey for estimating the extent of damage after a flood and landslide in southern Australia. The third part is a humanitarian aid program currently underway in Serbia and Bosnia and Herzegovina where landslide sites are accessed using geophysical methods, combining promotion and training of local engineers and students.


A Case Study to Detect the Extent of a Carbonate Outcrop in the Subsurface Using Microgravity

Authors: Y. Bouzidi*
Petroleum Institute, Abu Dhabi, United Arab Emirates
A microgravity experiment is conducted across a carbonate outcrop to detect its extent in the subsurface. An adapted procedure for the case study is used to correct and reduce the gravity measurements. The base station elevation level was used as the datum. The numerical calculation used to approximate and remove the effect of the material above the base station led to a gravity residual anomaly that correlates very well with an east dipping dense carbonate layer. From the interpreted subsurface through gravity modeling it was possible to estimate the dip angle which is found to be approximately 40° towards the east. The carbonate outcrop plays probably a role in the confinement and abundance of the groundwater at the near surface composed by very porous alluvial deposits.
Gypsiferous bedrocks and soils of Abu Dhabi and their implications for engineering geozoning

Authors: O. Abdelghany, M. Abu Saima, H. Arman, A. Fowler
Geology Department, UAE University, Al-Ain, Abu Dhabi, U.A.E.
Much of the bedrock in the Abu Dhabi Emirate consists of Oligocene to Miocene anhydritic to gypsiferous carbonate rocks and mudstones. The Holocene soils above these rocks also have significant sulphate contents. Both bedrocks and overlying soils present a number of engineering challenges related to dissolution cavitation and soil stability.
The 25 April 2012 Beni Haoua earthquake: instrumental intensity and consistency of ground motion modeling
Authors: Khadidja. Abbes, Nacima Benkaci, Abdennasser Slimani, Faouzi Gherboudj
Centre National de Recherche Appliquée en Génie Parasismique Rue Kaddour Rahim Prolongée, Hussein Dey, Alger;
Authors: Mohamed Djeddi
Université des Sciences et de la Technologie Houari Boumediene Bp 32 El Alia 16111 Bab Ezzouar Alger
This paper analyzes the instrumental intensity and examines the consistency of ground motion models, used for seismic hazard analysis in Algeria, with the Beni Haoua earthquake. The accelerograms recorded at 11triaxial stations following the April 25, 2012, are used in the evaluation of intensity based on a combined regression of peak ground acceleration (PGA) and velocity (PGV) amplitudes of the horizontal components provided by Tselentis and Danciu (2008). The Arias intensity is computed and compared with the instrumental intensity. To define how the structures react to ground motions, spectral acceleration is presented for a range of periods. The observed PGA of the Beni Haoua earthquake compared to the empirical ground motion prediction (GMPEs) Ambraseys (2005) show an overestimated model.

Geoelectrical Measurements as a Proxy for the Biophysicochemical Properties of Soils Irrigated with Sewage Water at Assiut City, Egypt
Authors: Reham S. Abd El-Rhman*, Gamal Z. AbdelAal
Geology Department, Faculty of Science, Assiut University, Assiut, Egypt;
Authors: Mohamed El-Ameen A. Faragallah
Soil and Water department, Faculty of Agriculture, Al-Azhar Univerity, Assiut, Egypt;
Authors: Mohamed H. Abdullah
Botany Department, Faculty of Science, Assiut University, Assiut, Egypt
At Arab El-Madabegh region, Assiut city, Egypt, many farmers are taking the advantage of the partially treated sewage water discharged from the sewage station for irrigating their agricultural lands as a common practice. Previous studies have shown that the long term use of the partially treated sewage water induced changes in the biophysicochemical properties of irrigated soils. Our objectives were to 1) develop empirical relationships between the geoelectrical measurements using resistivity method and some of the biophysicochemical properties of the soil samples, 2) validate the obtained empirical relationships using random samples. Eleven profiles were selected and twenty seven soil samples were retrieved from the study area at various depths (0-25, 25-60, and 60-90 cm). The soil samples were analyzed for physical (e.g., water content), chemical (e.g., soil ph, EC and some heavy metals), biological (Total Coliform counting) and geoelectrical (electrical resistivity) properties. A cross correlation between the biophysicochemical properties and electrical resistivity of the measured soil samples were performed and the cross correlated data are fitted with exponential trend line with correlation coefficients (R2) range from 0.53 to 0.79. To validate the obtained empirical relationships, additional three profiles were selected to collect additional samples at similar depths. The resistivity measurements of theses samples are used to estimate the biophysicochemical properties from the previously predefined empirical relationships. A good correlation was obtained between the measured and estimated values of biophysicochemical properties with strong correlation coefficient (R2) ranges from 0.83 to 0.98. The present study demonstrated the importance of using electrical resistivity measurements as a complementary tool to traditional soil sampling and a proxy to the biophysicochemical properties of soils. Moreover, resistivity measurements can reduce the cost and number of soil samples by providing proper guide for subsurface soil sampling and excavation from the spatial and temporal variations in the geoelectrical properties.
Can high-resolution marine geophysical data provide quantitative information useful for engineering design?

Authors: Mark E Vardy
Marine Geoscience Group, National Oceanography Centre Southampton, European Way, Southampton SO14 3ZH, UK
The amplitude, phase and frequency content of seismic reflection data contain quantitative information regarding the nature of the seafloor and sub-seafloor sediments. The petroleum industry has made significant developments over the past 20+ years to extract this information from reservoir-scale surveys using seismic inversion, allowing them to build detailed 3D models of hydrocarbon reservoirs. While some techniques (e.g., waveform inversion) are prohibitively computationally expensive to permit widespread application across all targets, other less expensive variants (e.g., impedance and amplitude-versus-angle inversion) have become a standard component of most interpretation workflows. In contrast, there has been very little progress toward the remote classification of near-surface sediments through the inversion of high-resolution marine geophysical data, with both academia and industry relying on extensive coring and cone penetrometer (CPTU) measurements. These provide very-high-resolution records of key subsurface properties (e.g., undrained shear strength, stiffness, grain size variation), but are expensive and time consuming to acquire and, more importantly, are only representative of the subsurface conditions at an isolated location at the time of sampling. High-resolution marine geophysical data can be acquired relatively quickly and cheaply, and at most infrastructure sites are standardly acquired at multiple stages of development across large potions of the site. These data are, however, commonly only used to produce a structural model. The construction of a reliable and detailed engineering ground model is a critical stage in the development of all offshore infrastructure, in deep or shallow water. In this talk, I will explore methods for maximizing the usefulness of high-resolution marine geophysical data, providing better calibration with existing borehole/CPTU data and deriving quantitative information (e.g., bulk density, porosity, Gmax). I will show that we can identify metre-scale stratigraphic changes, as well as subtle decimetre-scale structure, such as the grading within a glaciogenic sequence and a 40 cm thick landslide glide plane. The remote derivation of such high-fidelity soil properties has significant applications, both within academia and the offshore services/exploration industry.
Preliminary Test Investigation to Compare the Vertical Resolution of Different Geophones for Near Surface Shallow Seismic Investigation of an Abandoned Coal Mine Site

Authors: Ahmed I. Isiaka
University of the Witwatersrand, South Africa;
Authors: R. J. Durrheim
University of the Witwatersrand and CSIR, South Africa;
Authors: M.S.D. Manzi
University of the Witwatersrand, South Africa
High resolution shallow reflection seismic data was acquired across a borehole located within an abandoned coal mining site using three different types of geophones. The main objective of the study is to compare the vertical resolution of these geophones in order to choose the appropriate survey design for subsurface delineation of sinkholes or subsidence that might be present in the area. Two vertical geophones with resonant frequencies of 48 Hz and 100 Hz, and a horizontal geophone with resonant frequency of 14 Hz were employed in the investigation. Acquisition geometry was the same for all the geophones, and the energy source was provided by a sledge hammer hitting an aluminium plate. The data processing sequence was similar for all the geophones, and involves pre-stack, stacking, and post-stack stages. Signal attenuation with depth and dominant frequency vary among the geophones. The effect of multiples was noticed to be more severe in the data acquired with the 48 Hz vertical geophones, but less prominent in the 100 Hz vertical and the 14 Hz horizontal geophones. Post-stack, time-migrated sections generated for the three geophone types also show several reflections with depth for the 100 Hz vertical and 14 Hz horizontal geophones, as compared to the 48 Hz geophones.
Comparison of dispersion curves from horizontal and vertical components of particle motion

Authors: Zahid Khan, Magdi El-Emam, Mousa Attom, Aqeel Ahmed
Instructor, American University of Sharjah
Multichannel Analysis of Surface Waves (MASW) is increasingly being used to evaluate the shear wave velocity profile of sites. A typical test configuration of MASW involves recording of the vertical component of particle motion using vertically oriented geophones. Shear geophones, although pricier, are also being used in geophysical studies; however, their use in MASW has not been extensively evaluated. This study presents the simultaneous deployment of horizontal (shear) and vertical geophones to measure both the horizontal and vertical component of particle motion during the propagation of surface waves. The results indicate excellent correlation between the dispersion curves obtained from the recordings of horizontal and vertical geophones. The inverted velocity profiles also exhibit agreement up to a certain depth.

An Improved Iteration of Density Interface Inversion

Authors: Chong Zhang*, Danian Huang
College of Geo-Exploration Science and Technology, Jilin University, Changchun, China
This article first introduces the background of the research, and then puts forward the theory of the improved iteration inversion, to verify the new method, a numerical example is implemented, and a geophysical example is tested too, both examples show good viability of the given method.

Regional – residual gravity anomaly separation – A new processing technique

Authors: S. Barala*
Indian School of Mines, Dhanbad;
Authors: N. L. Mohan, R. R. Mathur
Osmania University, Hyderabad
The most difficult problems in gravity data interpretation is the separation of regional and residual gravity anomalies from gravity data. There are many techniques to separate the regional – residual anomalies. It is quite interesting that speech signals are similar to geophysical signals. In our paper a method is used to separate the regional residual anomalies which is generally used to separate the vowels in a given speech signal. The method is adapted to simulated anomalies and field data sets and proved that the method works for significant enhancement of the S/N ratio. This method would act as separation of regional and residuals of gravity data.
Understanding salt tectonics in Northern Tunisia - Insight from gravity data analysis

Authors: Imen Hamdi Nasr*
Unité de recherché de géophysique appliquée aux minerais et aux matériaux, département géologie, Faculté des sciences de Tunis, Tunisia and Faculty of Science of Bizerte, Tunisia;
Authors: Kawtahr Sebei, Haifa Boussigua, Benen Sarsar, Amiri Adnen, Oussama Abidi, Mouna Brahmi, Said Tlig, Inoubli Mohamed Hedi
Unité de recherché de géophysique appliquée aux minerais et aux matériaux, département géologie, Faculté des sciences de Tunis, Tunisia
Salt tectonics is one of the key fundamental problems of structural analysis in petroliferous basins, and is of broad practice prospecting in petroleum exploration and development stages. Many authors have dealt with salt dome folding and typology, especially after the discovery of ‘diapir plays’ within gas and oil-fields from the Gulf of Mexico and Iran (Talbot and Jaravis 1984; Talbot 1993; Jackson, Vendeville and Schultz- Ela 1994; Jackson 1995; Vendeville 2002; Krzywiec 2004; Talbot and Aftabi 2004). The study on salt tectonics in extensional basins (such as the Gulf of Mexico) has made great achievements (McBride et al., 1998), and salt tectonics research on compressive regime of foreland fold belt has also made progress, such as in the Persian Gulf Basin (Letouzey et al., 1995). The salt beds can change the occurrence of overlying horizons, forming various structural traps (Rowan, 1995). The salt bed itself is the most effective caprocks (Liang-Jie et al 2004). Focuses were performed on salt rising mechanism and geologic parameters effect such as: tectonic regime, basement faulting, initial salt layers thicknesses, overburden thickness, rate of sediment aggradations and salt dissolution.
Gravity for hydrocarbon exploration promotion

Authors: M. H. Inoubli*, I. Hamdi, O. Abidi, A. Amiri
University of Tunis-El Manar – Geoplus Sarl (Service Company)
Petroleum systems are often described as play perception within a region and used as a specific model and approach to recognize new petroleum accumulation intervals.
The identification of each play-component engages the use of seismic surveying, assessment techniques and geological synthesis to outline and situate prospective structures. Each model is labelled through its specific mark pattern; which develop into a measure, often used to look for comparable response model across the studied area. This develops into chiefly significant need as exploration moves to identify minor, more intricate, and less accessible goals. The richness of seismic data makes this method as the devoted tool for hydrocarbon exploration. So, from the total expenditure in geophysics huge amounts are paid for reflection seismic and almost nothing for the other methods as well as the other sectors. However seismic has its own limitations.
Fortunately, the development of new exploration techniques has improved exlorationists’ understanding and increased the efficiency of exploration. So, although targets are getting smaller, exploration and appraisal wells can now be sited more accurately and with greater chance of success through the use of multi-source information.
One of the successful tools of choice to assist with this endeavour has been the usage of Gravity data. Further more, the increasing complexity of the exploration targets is the driving force behind the integration of seismic and non-seismic methods into the subsurface geological modelling process. The availability of high quality digital data, and truly integrated workstation software, would enable interpreters to simultaneously model seismic and non-seismic data sets.
This paper reports the obtained results using gravity data for oil and gas exploration in various areas. Although gravity is less accurate than the universally used acoustic methods, measurements are inexpensive and are not time-consuming for data acquisition; gravity can be used in irregular and unreachable areas. Measurements are employed to delineate structural highs and lows which represent sedimentary thickness and facies change which constitute important aspects in the recognition and delineation of hydrocarbon exploration systems. This remains significant both during reconnaissance stage as well as mature exploration of a permit.
Gravity data interpretation for structure studies at a coastal area, southwest Saudi Arabia

Authors: Eslam Elawadi*
King Saud University, Riyadh, KSA;
Authors: Aseem Sulaiman
King Abdulaziz City for Science and Technology, Riyadh, KSA;
Authors: Saad Mogren
King Saud University, Riyadh, KSA
This study aims to map the basement depth and structure of the coastal area in the south western part of Saudi Arabia, as an aid to the groundwater potentially assessment. The gravity survey data was filtered and analyzed using different techniques finalized by 2-D modeling conducted along representative profiles to provide the topography and depth variations of the basement surface along the area. The depth to the basement rocks range from 0 m at the east and increase up to 2200 m at the west through local emulations related to the tilted-faulted blocks structure dominant in the Red Sea rift zone. Two faulting systems were recognized in the area; the first is normal faulting system trending in NNW-SSE direction and is related to the Red Sea rift, and the second representing the cross-cut oblique faulting system trending in NE-SW direction. The interaction between these faulting systems resulted in formation of a set of closed basins elongated at the NNW -SSE detection and terminated by the NE-SE faulting system. The geomorphology and sedimentary section of these basins qualify them for potentially groundwater accumulation.

Keynote Speech: Near-Surface Geophysics – Defining What, Why and How
Authors: A. P. Annan
Sensors & Software Inc.
Applied geophysics supports of many human endeavours. Historically, the most common use has been in oil and gas exploration closely followed by mineral exploration. Both resource-based communities constantly advance geophysical technology and mapping techniques on depths scales of hundreds to thousands of meters.

Seismic Reflection for Near-surface Characterization of Earthen Dams and Dikes: Upstream, Downstream

Authors: Richard D. Miller
Kansas Geological Survey, University of Kansas, Lawrence, KS;
Authors: Richard D. Markiewicz
U.S. Bureau of Reclamation, Denver, CO;
Authors: Julian Ivanov, Shelby Peterie
Kansas Geological Survey, University of Kansas, Lawrence, KS;
Authors: Jianghai Xia
China University of Geosciences, Wuhan, Hubei, China
High-resolution seismic reflection has been used successfully to characterize material and investigate a variety of engineering problems and hazardous settings associated with earthen dams, dikes, and abutments. Limitations and challenges of seismic reflection when interrogating these structures and lithologies are nontrivial and require critical thinking and unique approaches to acquisition and processing to allow meaningful and necessary interpretations and analysis. Seismic reflection has proved an effective tool for a range of applications and in this paper we examine mapping confining units for integration into engineering and design of impermeable structures; mapping lithologies and bedrock structures during safety analysis for earthquake retrofitting; delineating karst in bedrock beneath the dam core responsible for subsidence on the upstream side of structure; Vp/Vs in near-surface lacustrine sediments within 1 km of a major active fault scarp; and detecting high permeability zones within a glacial out-wash embankment. Extreme geometries and material variability associated with any man-made structure are the most formidable challenge to seismic imaging. Inconsistent source wavelets, out-of-the-plane energy, extreme statics (topography and velocity based), and source noise (disproportionately high percentage of surface waves) are all problems that are not unique to earthen dams, dikes, and levees, but they are certainly more prevalent with those types of structures. Success of the technique in each of these settings relied on confident and defensible interpretation of reflection energy at each step in the processing flow.
Hydrogeological and Geophysical investigations of a Pilot Area between Jabal Hafit and Oman Border, Al Ain, UAE

Authors: A. Murad, S. Hussein*, A. Gabr, H. Baker, K. Al Bloushi, A. Aldahan
Geology Department, United Arab Emirates University, Al Ain, UAE
A pilot area in Al Ain City, United Arab Emirates (UAE), located between Jabal Hafit to the west and Oman border to the east has been selected for the study of variability in groundwater conditions. Many wadies run through the area and are originated from the Oman Mountains ranges, which form the main catchment for both surface and groundwater. Subsurface and subsurface investigations of these wadies are vital for better understanding of the aquifer system condition and groundwater sustainability. It is believed that the recent wadies alluviums follow the configuration of ancient paleochannels thus provides interesting extended aquifers at depth. In these Quaternary alluviums, which are composed of a mixture of gravel, sand and clay beds, the groundwater level depth varies from 5 m to 80 m having maximum depth nearby Hafit Mountain and the minimum in the eastern side closed to Oman Mountains. Transmissivity of the alluvium aquifer varies between about 1837 m2/day in the unconfined and 2449 m2/day in the confined with corresponding permeability values at 30 m/day and 40 m/day respectively. The two dimensional (2D) Electrical Resistivity Tomography (ERT) profiles measured across selected wadies confirm the spatial extension of the Quaternary deposits. Qualitative and quantitative interpretation of the processed data indicated different hydrostratigraphic units of the alluvium section which may represent ancient paleochannels.
Estimating aquifer hydraulic parameters from electrical resistivity measurements; a case study at Khuff Formation Aquifer, Al Quwy’yia Area, Central of Saudi Arabia
Authors: Mohamed Metwaly*
Archaeology Dept., College of Tourism and Archaeology, King Saud University, S.A.;
Authors: Mohamed El Alfy
CIPW, Prince Sultan Institute for Environmental, Water and Desert Research, King Saud University, S.A;
Authors: Eslam Eawad
Deanship of Scientific Research, King Saud University, S.A;
Authors: Ahmed Ismail, Gad El-Qady
National Research Institute of Astronomy and Geophysics (NRIAG), Cairo, Egypt
Measuring the aquifers hydraulic parameters is an essential process for groundwater management and sustainable developments. These parameters are typically measured from the expensive and longtime pumping test experiments that require a number of water wells. Surface electrical resistivity measurements are recently used as less expensive alternative to estimate aquifers hydraulic parameters. A number of 20 vertical electrical resistivity sounding (VES) were acquired at Khuff aquifer in Al Quwy’yia area, to estimate the hydraulic parameters of Khuff aquifer. Based on the electrical resistivity measurements, the formation factor, porosity, hydraulic conductivity and transmissivity were estimated from the electrical resistivity measurements. These estimated parameters were compared to the parameters obtained from the previous pumping test experiments. The transmissivity values showed a reasonable comparison with the values measured from a previous pumping test experiments. According to the results of this study, surface electrical resistivity proved to be a successful tool in characterizing the Khuff aquifer and estimating most of the aquifer’s hydraulic parameters.
Groundwater Exploration Using Airborne Electromagnetic Data
Authors: Craig Annison*, Simon Wetherley
CGG Multiphysics
Airborne electromagnetic surveys are a rapid, effective and economical way of determining the geometry, structure, and quality of ground water aquifers. Here we present three examples of airborne EM applied to ground water exploration applications.
The first example shows how a DIGHEM helicopter frequency-domain EM (HFEM) survey in northeast Brazil was used to identify ground water associated with fractures and faults in a gneiss terrane. DIGHEM’s extremely high spatial resolution and ability to detect subtle variations in subsurface conductivity allowed it to identify the fractures filled with ground water.
In the United Arab Emirates, TEMPEST data was used to distinguish fresh water from saline water in the main conglomerate aquifer. Good correlation of the interpreted distribution of fresh ground water from the EM data to the distribution derived from boreholes in the area shows the EM data is able to map the fresh ground water. Borehole conductivity logs compare favourably to the derived conductivity from the EM survey.
The final example illustrates how airborne EM data can be used to map palaeochannels, basement/regolith contacts, aquifer geometry and salt water intrusion in the coastal district of the Pilbara in northern Western Australia.

Mapping coastal aquifer and sea water intrusion using time-domain electromagnetic method, North Oman

Authors: Hesham El-Kaliouby*
Sultan Qaboos University, Earth Science Dept., Oman & National Research Center, Geophysics Dept., Egypt
Time Domain Electromagnetic (TDEM) has been widely used in mapping and assessment of groundwater resources and sea water intrusion along coastal alluvial plains. TDEM soundings were used to define aquifer zones in the alluvial aquifer in Al Khoud coastal area in North Oman. The main aquifer zones, composed of clean gravels, clayey gravels, and cemented gravels, could be identified, along with the basal contact of the aquifer. The TDEM data also used to map the depth to the interface between freshwater and saline-water along the coast. The inland extents and thickness of the saline water were mapped along two NWSE TDEM profiles. The depths to the intrusion zone was investigated using different transmitter loop areas. The resistivity distribution derived from TDEM data agrees closely with the electrical conductivity and resistivity logs from available well data in the study area. TDEM proved to be a successful tool for mapping saline zones and fresh water in arid environment with high depth of penetration and speed of operation.
Geophysical Prospecting of Groundwater in Carbonate Discontinuous Aquifer in Morocco

Authors: Mohamed Rouai*, Khaoula Qarqori
Earth Sciences Department, Faculty of Sciences of Meknes, Moulay Ismail University, Morocco
We present a case study of hydrogeophysical prospecting in discontinuous karstic Lias reservoir from Moroccan Middle Atlas. The geophysical surveys applied mainly Electrical Resistivity Tomography imaging the 2D subsurface karst. This technique appears to be an appropriate geophysical tool, especially by improving understanding of fracture network and reservoir geometries.
Additional investigations using electromagnetics and microgravimetry surveys were also performed for more precision and to characterize favorable hydrological zones.
Hydrogeophysical study for the groundwater flooding in Al-Borgeig area, Northern Sudan

Authors: M. A. Mohamed-Ali*, E. A. Hassan, A. I. Ali
Faculty of Earth Sciences and Mining – University of Dongola, Wadi Halfa, Sudan
Some people lost their houses because of collapse due to groundwater flooding in Al-Borgeig area in Northern Sudan. The objective of the current study was to evaluate if and how the decreased groundwater pumping and the increased direct use of water from the Nile increase the groundwater flooding, control its patterns and groundwater flow directions. The groundwater level and the estimated groundwater flow directions in the surrounding Quaternary aquifer were determined with electrical resistivity tomography surveying and water level data from monitoring wells. ERT results indicate in some local areas where groundwater flooding negative impacts severe are associated with irrigation in the nearby topographical high farms of sandy deposits. The high transitivity and high permeability of the underneath sandy layers and mud clay soils respectively play vital role in the degree of the groundwater flooding.
Utilization of isotopes in hydrogeological studies in UAE: A review

Authors: S. Parimalarenganayaki*, Mohamed Mostafa Mohamed
Department of Civil and Environmental Engineering, UAE University, P.O. Box: 15551, Al-Ain, United Arab Emirates;
Authors: Ahmed A. Murad
Department of Geology, College of Science, UAE University, P.O. Box: 17551, Al-Ain, United Arab Emirates
The United Arab Emirates (UAE) is located in the southeastern corner of the Arabian Peninsula. The water demand for domestic, industrial and agricultural activities are met by conventional (rainfall recharge, falajes, springs and flash floods) and non-conventional water resources (desalinated water and treated waste water). The limited availability of fresh water resources and increasing population in the UAE creates more demand on the fresh water resources. Over usage of freshwater resources creates hydrological stress on the aquifer system. This situation alerts the hydrogeologists to plan for better freshwater management systems in UAE. In order to adopt the best water management plan, it is necessary to understand the rainfall pattern, sources of groundwater recharge, movement of groundwater, evaporation process and changes in water quality which are taking place in the hydrological system by means of suitable technology. During past three decades many studies had been carried out using environmental isotopes to understand the hydrological problems associated with arid climate in UAE. The aim of the present study is to review the utilization of isotopes in hydrogeological studies in UAE. This study will help decision makers to understand the past and present conditions of freshwater systems in UAE.
Utilization of isotopes in hydrogeological studies in UAE: A review

Authors: S. Parimalarenganayaki*, Mohamed Mostafa Mohamed
Department of Civil and Environmental Engineering, UAE University, P.O. Box: 15551, Al-Ain, United Arab Emirates;
Authors: Ahmed A. Murad
Department of Geology, College of Science, UAE University, P.O. Box: 17551, Al-Ain, United Arab Emirates
The United Arab Emirates (UAE) is located in the southeastern corner of the Arabian Peninsula. The water demand for domestic, industrial and agricultural activities are met by conventional (rainfall recharge, falajes, springs and flash floods) and non-conventional water resources (desalinated water and treated waste water). The limited availability of fresh water resources and increasing population in the UAE creates more demand on the fresh water resources. Over usage of freshwater resources creates hydrological stress on the aquifer system. This situation alerts the hydrogeologists to plan for better freshwater management systems in UAE. In order to adopt the best water management plan, it is necessary to understand the rainfall pattern, sources of groundwater recharge, movement of groundwater, evaporation process and changes in water quality which are taking place in the hydrological system by means of suitable technology. During past three decades many studies had been carried out using environmental isotopes to understand the hydrological problems associated with arid climate in UAE. The aim of the present study is to review the utilization of isotopes in hydrogeological studies in UAE. This study will help decision makers to understand the past and present conditions of freshwater systems in UAE.
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