SHALLOW SUBSURFACE MAPPING IN RISHIKESH REGION

Abstract

Garhwal region near Rishikesh lie in the seismic zone V and thus is prone to seismic risks. Stress gets accumulated as the constant thrust between Eurasian Plate and Indo-Australian Plate in always in action. The region I worked on is prone to seismic activities. The main objective of the presented work is to study the velocity structure in Rishikesh, Himalya by employing Multi Channel Analysis of Subsurface wave method and using it again for the estimation of bed thickness. The Rayleigh waves always show dispersive characteristics which are utilized for imaging the shallow subsurface layers. The accuracy of MASW method depends on the precision of the determined phase velocities for the Rayleigh waves. Multi-channel records are useful in identification and isolation of noise. The multi-channel record is then decomposed into time and frequency format thus permitting the real time maximization of the Signal/Noise ratio during the processing stages. Using “Seisimager”, the MASW data were processed and finally interpreted that the shear wave velocity is in the range 320-700 ms-1. Covering a depth range of 40-50 m.