Abstract

In land seismic surveys placement of shot (blasting of explosive) in an appropriate near surface layer plays an important role in terms of transmission of shot generated energy. An optimally selected shooting layer is expected to result in good energy transmission and better data quality. Normally a higher velocity layer is expected to give rise to better energy transmission and conversely in case of lower velocity. On contrary, deviations from this general expectation, have been observed in North Cambay Basin, India (along eastern basin margin) wherein , at places, sandy high velocity layer results in deterioration of energy transmission from a blasted shot and lower velocity layer with more clay content shows energy transmission which is better than expected from a lower velocity layer.