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Integration of seismic refraction tomography and electrical resistivity tomography in engineering geophysics for soil characterization

  • Ahmed J. R. Al-Heety
  • Zainab M. Shanshal
Original Paper

Abstract

The use of both seismic refraction tomography (SRT) and electrical resistivity tomography (ERT) techniques have commonly been used to detect physical properties in the subsurface materials in order to map the subsurface geological features and soil characterization in the site investigations. Using of both techniques increases confidence in interpretation to limit inaccurate interpretation due to the large amount of heterogeneity in the near surface. Twelve shallow seismic refractions and ten profiles for electrical resistivity were conducted in the Teaching Hospital Project site in Mosul University, Iraq. The linear arrays by using 12 geophones with 10 Hz frequency are used to SRT while ERT traverses were conducted with a total length (280 m) by using Wenner array with an initial electrode spacing of 3 m. Both SRT and ERT data were acquire and interpreted using SRT method and ERT methods to create tomogram velocity models and two dimension resistivity images by using the SeisImager/2D and RES2DINV software, respectively. The seismic velocity values show that the site has three layers, just as follows: the first one corresponded to recent superficial deposits and is characterized by low velocity ranging from about 340 to about 700 m/s. The second one corresponded mostly to the river deposits composed especially of river terraces and clays are characterized by relatively highest velocity values ranging from about 840 m/s to about 1700 m/s. The third one corresponded to the upper part of Fat’ha (Lower Fars) formation which is mostly composed of marl layers and is characterized by high velocity ranging from about 1900 m/s to about 2800 m/s. Interpretations of 2D resistivity profiles indicated alteration zones at depth. It was determined that the material could be classified into two main zones. The first zone has a relatively high true resistivity value ranging from about 80 to about 320 Ω m with a thickness ranging from about 1 to about 25 m, which is mainly consisted of conglomerate, gravel and sand (weathered layer). The second zone has a relatively low true resistivity value reached to 80 Ω m which represents upper part of Fat’ha (Lower Fars) formation deposits which mainly consisted of clays. The two geophysical methods were used to be enjoined the better way to aid the interpretation and evaluate the significance and reliability of the results obtained in each single method. It is demonstrated that engineering geophysics is able to provide solutions for determining subsurface properties and that different prospection techniques are necessary for developing a reasonable model of the subsurface structure. Hence, the third layer is suggesting for engineering and foundation purposes.

Keywords

Refraction tomography Electrical resistivity tomography Site investigation Inversion 2D imaging 

References

  1. Aizebeokhai AP, Olayinka AI, Singh VS (2010) Application of 2D and 3D geo-electrical resistivity imaging for engineering site investigation in a crystalline basement terrain, southwestern Nigeria. Environ Earth Sci 61:1481–1492CrossRefGoogle Scholar
  2. Al-Dabbagh TH, Al-Naqib SQ (1991) Tigris River terrace mapping in northern Iraq and geotechnical properties of the youngest stage. Quat J Eng Geol Geol Soc Spec Pub 7:603–609Google Scholar
  3. Al-Joubory MA (1988) Geology of Mosul area East Tigris River,M.Sc. thesis, science college,Mosul university, 158 p. (In Arabic)Google Scholar
  4. Auken E, Pellerin L, Christensen NB, Sorensen K (2006) A survey of current trends in near-surface electrical and electromagnetic methods. Geophys J R Astron Soc 71(5):249–260Google Scholar
  5. Barker RD (1981) The offset system of electrical resistivity sounding and its use with multicore cable. Geophys Prospect 29:128–143CrossRefGoogle Scholar
  6. Bellen RC, Dunnington HV Van, Wetzel R, Morton D (1959) LexiqueStratigraphique, International. Asie, Iraq, 3c. 10a, 333 pGoogle Scholar
  7. Bery AA (2013) High resolution in seismic refraction tomography for environmental study. Int J Geosci 4:792–796CrossRefGoogle Scholar
  8. Bowles JE (1982) Foundation analysis and design, 2nd edn. McGraw-Hill International Book Company, London, 587 pGoogle Scholar
  9. Bridle R (2006) Plus/minus refraction method applied to 3D Block, SEG Expand. Abstr.25, 1421Google Scholar
  10. Buday T (1980) The regional geology of Iraq stratigraphy and paleogeography. Dar Al-Kutub publication House, Mosul -Iraq, 352 pGoogle Scholar
  11. Dahlin T, Zhou B (2004) A numerical comparison of 2D resistivity imaging with ten electrode arrays. Geophys Prospect 52:379–398CrossRefGoogle Scholar
  12. Griffiths DH, Barker RD (1993) Two dimensional resistivity imaging and modeling in areas of complex geology. J Appl Geophys 29:211–226CrossRefGoogle Scholar
  13. Han-Lun H, Brian JY, Chien-chih C, Yue-Gau C (2010) Bedrock detection using 2D electrical resistivity imaging along the Peikang River, central Taiwan. J Geomorphol 114:406–414CrossRefGoogle Scholar
  14. Hauck C, Muhll DV, Maurer H (2003) Using DC resistivity tomography to detect and characterize mountain permafrost. Geophys Prospect 51:273–284CrossRefGoogle Scholar
  15. Hodgkinson J, Brown RJ (2005) Refraction across an angular unconformity between onparallel TI media. Geophysics 70:D19CrossRefGoogle Scholar
  16. Jassim SZ, Goff JC (2006) Geology of Iraq. first Edition, Dolin, Prague and Moravian Museum, Brno, Czech Republic, 408 PGoogle Scholar
  17. Keller GV, Frischknecht FC (1966) Electrical methods in geophysical prospecting. Pergamon Press Inc, OxfordGoogle Scholar
  18. Lankston RW (1989) The seismic refraction method: a viable tool for mapping shallow targets into the 1990s. Geophysics 54:1535–1542CrossRefGoogle Scholar
  19. Loke MH (2001) Electrical imaging surveys for environmental and engineering studies. A practical guide to 2-D and 3-D surveys, RES2DINV Manual, IRIS Instruments, www.iris-instruments.com
  20. Loke MH (2009) Tutorial: 2-D and 3-D electrical imaging surveys. www.geoelectrical.com
  21. Loke MH, Barker RD (1995) Least-squares deconvolution of apparent resistivity pseudo sections. Geophysics 60(6):1682–1690CrossRefGoogle Scholar
  22. Loke MH, Barker RD (1996) Rapid least-squares inversion of apparent resistivity pseudosections using a quasi-Newton method. Geophys Prospect 44:131–152CrossRefGoogle Scholar
  23. Mutib Marwan (2000) “New contribution to the geology of Mosul area from geo-electric investigation, Ph.D. thesis, Science college, Mosul university, 136 p. (In Arabic)Google Scholar
  24. Parasnis DS (1997) Principles of applied geophysics, 5th edn. Chapman and Hall, LondonGoogle Scholar
  25. Redpath BB (1973) Seismic refraction exploration for engineering site investigations, Technical Report E-73-4, US Army Engineer Waterways Experiment Station. Ex- plosive Excavation Research Laboratory, LivermoreCrossRefGoogle Scholar
  26. Sass O (2007) Bedrock detection and talus thickness assessment in the European Alps using geophysical methods. J Appl Geophys 62:254–269CrossRefGoogle Scholar
  27. Stummer P, Maurer HR (2001) Real-time experimental design applied to high-resolution direct-current resistivity surveys. International Symposium on Optical Science and Technology, Expanded Abstracts, pp 143–150Google Scholar
  28. Yilmaz O, Eser M, Berilgen M (2006) “Seismic, Geotechnical, and Earthquake Engineering Site Characterization”, 76th Annual International Meeting, SEG, Expanded Abstract, Vol.25, pp. 1401–1405Google Scholar
  29. Zhang J, Toksöz MN (1998) Non-linear refraction travel time tomography. Geophysics 63(5):1726–1737CrossRefGoogle Scholar

Copyright information

© Saudi Society for Geosciences 2015

Authors and Affiliations

  1. 1.Department of Geology, College of ScienceMosul UniversityMosulIraq

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