High Resolution in Seismic Refraction Tomography for Environmental Study

Andy A. Bery

Geophysics Section, School of Physics, Universiti Sains Malaysia, Penang, Malaysia.

DOI: 10.4236/ijg.2013.44073                

Abstract

Seismic refraction tomography (SRT) involves more complex mathematic algorithms to fit more flexible model. In the field procedure SRT in generally needs more shot points than standard seismic refraction survey to obtain high resolution profile. In this seismic refraction study, we have used 9 shot-points for inline and 10 shot-points for offset in purpose to obtaine high resolution of seismic refraction tomography. During a recent geophysical test site, the subsurface material was mapped along survey line using seismic refraction method. Analyses of the site investigation data revealed that the studied site was made up of two layers of the subsurface. The upper layer has velocity values with range of 500 m/s to1500 m/s which can be classified as unconsolidated surface deposits and mixtures of unsaturated sands and gravels. Meanwhile the lower layer has velocity values with range of2000 m/s to5500 m/s which is classified as compacted fine’s soil due to high pressure of the overburden. Analysis of seismic refraction data demonstrated that refraction tomography software systems are able to reveal subsurface material which represented by their seismic velocity value. Furthermore, the velocity model obtained in this study is agreed with its synthetic modelling result as initial model. This validity and reasonable results was able to assist in interpretation of the seismic refraction method for the environmental study.

Keywords

Seismic Refraction Tomography; Seismic Velocity; Synthetic Modelling; Validity; Environmental

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	P. J. Carpenter, I. C. Higuera-Diaz, M. D. Thompson, S. Atre and W. Mandell, “Accuracy of Seismic Refraction Tomography Codes at Karst Sites, Geophysical Site Characterization: Seeing beneath the Surface,” Proceedings of a Symposium on the Application of Geophysics to Engineering and Environmental Problems, San Antonio, 6-10 April 2003, pp. 832-840.
[2]	B. J. Cramer and D. R. Hiltunen, “Investigation of Bridge Foundation Sites in Karst Terrane via Seismic Refraction Tomography,” 83rd Annual Meeting Compendium of Papers CD-ROM, Transportation Research Board, Washington DC, 11-15 January 2004.
[3]	A. A. Bery and R. Saad, “Correlation of Seismic P-Wave Velocities with Engineering Parameters (N Value and Rock Quality) for Tropical Environmental Study,” International Journal of Geosciences, Vol. 3, No. 4, 2012, pp. 749-757. doi:10.4236/ijg.2012.34075
[4]	D. R. Hiltunen and B. J. Cramer, “Geophysical Characterization of Bridge Foundation Sites in Karst Terrane,” 85th Annual Meeting Compendium of Papers CD-ROM, Transpotation Research Board, Washington DC, 22-26 January 2006.
[5]	J. R. Sheehan, W. E. Doll and W. A. Mandell, “An Evaluation of Methods and Available Software for Seismic Refraction Tomography Analysis,” Journal of Environmental and Engineering Geophysics, Vol. 10, No. 1, 2005, pp. 21-34. doi:10.2113/JEEG10.1.21
[6]	A. A. Bery and R. Saad, “Clayey Sand Soil’s Behaviour Analysis and Imaging Subsurface Structure via Engineering Characterizations and Integrated Geophysical Tomography Modelling Methods,” International Journal of Geosciences, Vol. 3, No. 1, 2012, pp. 93-104. doi:10.4236/ijg.2012.31011
[7]	B. B. Redpath, “Seismic Refraction Exploration for Engineering Site Investigations,” Technical Report E-73-4, US Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, 1973.
[8]	M. L. Rucker, “Applying the Seismic Refraction Technique to Exploration for Transportation Facilities,” Geophysics 2000 Conference Proceedings, Missouri Department of Transportation, St. Louis, 2000.
[9]	J. M. Reynolds, “An Introduction to Applied and Environmental Geophysics,” John Willey & Sons Ltd., Hoboken, 1997.
[10]	S. K. Pullammanappallil and J. N. Louie, “A Generalized Simulated Annealing Optimization for Inversion of First-Arrival Times,” Bulletin of the Seismological Society of America, Vol. 84, No. 5, 1994, pp. 1397-1409.
[11]	J. E. Vidale, “Finite Difference Calculation of Travel Times,” Bulletin of the Seismological Society of America, Vol. 78, No. 6, 1988, pp. 2062-2076.
[12]	A. A. Bery, “Merge-Optimization Method of Combined Tomography of Seismic Refraction and Resistivity Data,” ISRN Geophysics, Vol. 2012, 2012, Article ID: 293132. doi:10.5402/2012/293132
[13]	A. A. Bery and R. Saad, “Tropical Clayey Sand Soil’s Behaviour Analysis and Its Empirical Correlations via Geophysics Electrical Resistivity Method and Engineering Soil Characterizations,” International Journal of Geosciences, Vol. 3, No. 1, 2012, pp. 111-116. doi:10.4236/ijg.2012.31013