SHALLOW SEISMIC REFRACTION SURVEY IN SUJAWAL DISTRICT THATTA (SIND)

Abstract

A project of shallow seismic refraction problem was carried out in Sujawal of Distt. Thatta (Sind), for the completion of dissertation requirements. The purpose of survey was to establish velocity- lithology relationship, to determine thickness of different subsurface layers and to trace the dipping nature of subsurface layers. To achieve this, true velocities, depth and dipping angles were obtained from TX -graphs. The nature of dipping refractors was mapped by SLOTNICK'S METHOD. The interpretation of seismic refraction data shows three layers having velocities Vo, VI, V2 respectively. Velocity of first layer ranges from 1346.8 m/sec to 1767.3 m/sec whereas thickness of this layer ranges from 80.3 m to 182.7 m. The velocity 05 range of this layerindicates a lithology coarse sand, Dry sand and gravel. The velocity in second layer VI varies from 2099.5 m/sec to 2466.2 m/sec.The depth of this layer varies from 264.3 m to 646.6 m. This velocity range is indicative of sandstone. · Similarly, the velocity in third layer V2 varies from 2597.4 m/sec to 4167.4 m/sec. This velocity range of third layer shows the presence of sandstone with limestone.