Analyzing Coulomb Stress Changes and Seismic Activity following the 1999 Chamoli Earthquake in Garhwal Himalaya, India

Abstract

Abstract On March 29, 1999, the magnitude Mw 6.6 Chamoli earthquake ruptured the Garhwal Himalayan region of the North-Western Himalayas. We investigated the correlation between changes in Coulomb stress and the distribution of aftershocks in the region of the 1999 Chamoli earthquake, which occurred on and off the Main Central Thrust fault. The USGS identified it at 30.49° N and 79.29° E, at a depth of 19 km; the GCMT solution suggested thrust faulting on a fault that slanted slightly to the north. On the plane that dips gently to the north (strike 290°, dip 14°, rake 90°), there is thrust motion, according to the moment tensor solution derived from the USGS earthquake catalogue. Furthermore, 4.34E + 18 Nm is the calculated seismic moment for this event. To understand the mechanisms behind the aftershocks, an in-depth study of this event and its subsequent seismic activity has been carried out. Based on the position of the aftershock sequence, seismicity was primarily limited to the southern region of the MCT zone. A fault area of 26.07 X 13.93 km2 has been obtained. The computed dip slip is 0.81m, while the shear stress change over the area is 1.72Nm.