October 19, 1991 Earthquake: Chamoli, Uttarkashi, New Delhi, Chandigarh, India

Two events about 1.6 seconds apart. At least 2,000 people killed, more than 1,800 injured and 18,000 buildings destroyed in the Chamoli-Uttarkashi area. Some damage occurred at Chandigarh and New Delhi. Felt in northern India, western Nepal and northeastern Pakistan. Landslides occurred in the epicentral area. A 30-meter deep crack was noted in the Uttarkashi area. (reference #1053)

1500 deaths, 1383 injured, and $60 million damage, 7500 buildings collapsed and important number of structures damaged, 500 villages destroyed . (reference #1250)

The Uttarkashi earthquake of 20 October (19 October,

21 h 23 m 15 + 1.51 s, UTC) 1991 was associated with

the Main Central Thrust zone of Himalaya (just south of

the Vaikrita thrust) at 30.77 + 0.023 N, 78.77 + 0.018 E at a depth of 15 + 1.5 km (constrained by depth phase pP-P, ISC)16. Having claimed about 2000 human lives, it was the most significant earthquake of 1991. With a Mw 6.6, Ms 7.0 (USGS) and intensity VIII, this event is characteristic of the present-day motion on the thrust-fault system. The Uttarkashi earthquake and aftershocks were well recorded at many new seismograph and accelerograph stations established in the Himalayan region under the Himalayan seismicity study programme of DST16. These stations were maintained by IMD, Roorkee University and Wadia Institute of Himalayan Geology (WIHG). About 30 local analogue stations were deployed for aftershock studies by these three organizations and GSI as well as NGRI. A detailed intensity survey was carried out by GSI17. Study of this earthquake with different data sets yielded better understanding of the faulting process of a major earthquake in the Himalayan frontal arc region. (reference #1266)