Optimum Geometry For Roll Along In Seismic Refraction Tomography For Adequate Sampling And Coverage Of The Subsurface

Abstract

Seismic refraction is mostly used in geotechnical work to determine the velocity of the overburden and the refractor velocity. Roll along, in seismic refraction tomography, is important for three reasons. These are to increase the profile length beyond the distance dictated by the source and the instrument (number of receiver and cable length), to increase the signal to noise ratio and to ensure an adequate overlap in the subsurface data coverage. Some pitfalls often encountered by geoscientists employing refraction tomography and examples of the wrong methodology often employed in refraction roll along tomography with their effect on tomographic section are presented. At the end of filtering and data analysis it was obvious from the ray tracing and results obtained that roll along in seismic refraction tomography principle help in achieving adequate subsurface data coverage, improvement in signal to noise ratio and achieving the desired profile length when compared with two distinct independent profiles taken along the seismic line.