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

The seismicity of northeast India has been studied in the light of the known geotectonic features based on the data from 1881 to 1972. Now focal mechanism solutions of earthquakes using double couple hypothesis have been discussed with reference to the plate theory of global tectonics and the geological faults. It was found that the constant b in Gutenberg-Ricliter's frequency magnitude relationship was nearly I for both the periods of observations namely 1920-1972 and 1963-1972 which was in agreement with the other highly seismic regions of the world. Most of the new fault plane solutions show significant strike slip movements with thrust faulting in this region. Near the main boundary fault in northeast Himalaya, the pressures are oriented almost along the strike of the fault while along the Manipur-Burina border region, the pressures are acting at right angles or at acute angles to the mountains and are shallow dipping.