Seismicity and focal mechanism of some recent earthquakes in North-east India and neighbourhood

Abstract

The seismicity of northeast India has been studied in thelight of the known geotectonic features based on the data from 1881 to 1972.Now focal mechanism solutions of earthquakes using double couple hypothesishave been discussed with reference to the plate theory of global tectonicsand the geological faults.It was found that the constant b in Gutenberg-Ricliter's frequencymagnitude relationship was nearly I for both the periods of observationsnamely 1920-1972 and 1963-1972 which was in agreement with the otherhighly seismic regions of the world. Most of the new fault plane solutionsshow significant strike slip movements with thrust faulting in this region.Near the main boundary fault in northeast Himalaya, the pressures areoriented almost along the strike of the fault while along the Manipur-Burinaborder region, the pressures are acting at right angles or at acute angles tothe mountains and are shallow dipping.