Seismic Survey Suitable for mapping of layered sedimentary sequences Widely used in search of oil and gas. Small scale mapping of near surface sedimentary layers , location of water table, Site investigation of foundation conditions (including depth of bedrock). In engineering site investigation, Vp and Vs measurement for near surface layers allows direct calculation of Poisson's ratio and estimation of elastic moduli, which provides valuable information on in situ geotechnical properties. Offshore geological surveys Refraction Reflection ( most widely used geophysical technique) Large/regional scale experiments for study of the entire crust or lithosphere. Estimation of depth of bedrock in foundation site investigation. In engineering purpose, derive relation between velocity and hardness of rock for quarrying operations, nature of landfill materials. Exploration of underground water in conjunction with resistivity methods (as there is a large difference in velocity of dry and