THE UTTARKASHI EARTHQUAKE OF 20 OCTOBER 1991 - FIELD OBSERVATIONS

The epicentre of the destructive 20 October 1991 earthquake is in the north-east of the Uttarkashi region of the Higher Himalaya. The earthq uake was felt up to 250-350 km away from Poh and Keylong in the north to Delhi in the south and beyond Chandigarh in the west. Seismologists of the Seismotectonic Group of Wadia Institute of Himalayan Geology s tudied fissures, surface breaks, and the foreshock and aftershock acti vity caused by this event. Land fissures show normal dislocations of 0 .06-1 m, run E-W and NE-SW in the epicentral region and could be follo wed for 30-40 km.