Regional plate tectonics from Himalayan earthquakes and their prediction

Regional plate tectonics provides a broad basis for assessing the magnitude of earthquakes, besides understanding the orientation of stresses producing such earthquakes. Keeping this in view, reliable focal mechanism solutions obtained during 1972 to 1975 in the Himalayan region have been discussed. Four radial vertical sections showing the depth plot of earthquakes near the northern boundary of Indian plate were drawn based on the data during the years 1964-1974 but no clear dipping of the Indian plate could be seen. In the mechanism solutions except for Kinnaur (1975) and Assam (1950) earthquakes, thrusting was observed near the foothills. The pressures are generally acting at right angles to the mountains and the slip vectors also show a northerly trend. An earthquake located near Burma border, however, showed normal faulting and needs further explanation. However, the present movements of the Indian plate and their inferred changes show that northeast India will continue to be highly seismic.