Seismic refraction investigations for Mapping of subsurface low velocity zones At Kot Sarang anticline area Distt. Attock

Abstract

Shallow Seismic refraction investigations were carried out to study the weathered and subweathered low velocity surface l ayers in and around kot Sarang anticline, Talagang District Attock . This pertained to the dis sertation req uirement of the Quaid-i -Azam University for partial fulfilment of M.Sc. (Geophysics) degree in collaboration with Seismic party No.5 of t he Oil and Gas Development Corporation working in Talagang area. Four cross seismic profiles were observed using reversed refracti on shooting techni que wi th each refracti on spread of 270 meters 1 engtlr. In this way refraction shot points were shot resulting in refraction seismograms fr om which tra vel time data were read. This was then converted in to computer programmed travel ti me curves . Some of t hese curves were two layer cases while others were three layer cases . Apparent velocities and other type of data were then evaluated from t hese travel time curves which was later used for compu ter solution of dip angles . true velocities of layers , t heir perpendicu - lar and vertical depths geometry, Isopach and Isovelocity contour maps alongwith velocity sections along the seismic prufiles .