1991 Uttarkashi earthquake

6.8 magnitude earthquake in India November 2019 June 2017 1991 Uttarkashi earthquake 1991-10-19 21:23:14 usp0004y1r 317038 India 20 October 1991 02:53 Indian Standard Time (UTC+5:30) ~ 45 seconds 6.8 w y 11.6 km mi 0 on 30.75 78.82 region:IN_type:event inline,title Reverse Uttar Pradesh India $60 million 9 0.31 g 768–2,000 dead 1,383–1,800 injured The 1991 Uttarkashi earthquake (also known as the Garhwal earthquake) occurred at 02:53:16 Indian Standard Time (UTC+05:30) on 20 October with a moment magnitude of 6.8 and a maximum Mercalli intensity of IX (Violent). This thrust event was instrumentally recorded and occurred along the Main Central Thrust in the Uttarkashi and Gharwal regions of the Indian state of Uttarakhand (then still part of Uttar Pradesh). High intensity shaking resulted in the deaths of at least 768 people and the destruction of thousands of homes. Tectonic setting Geology of the Himalaya The Garhwal division in northern India, flanked by the Tons River to the west and the Alaknanda River to the east, is located at the boundary of the Indian and Eurasian tectonic plates. In the region, the Indian plate is moving northeastward at a rate of 5 cm us per year. The Main Central Thrust is the primary northwest-striking structure and dips to the north at 30–40°. The fault plane solutions from the parametric catalogs for the 1991 and 1999 events showed low-angle thrust faulting with varying amounts of strike-slip movement.Himalayan hazard study on the basis of stress and strain state of 1991 Uttarkashi earthquake using Coulomb stress transfer model D. K. Gupta D. Bhowmick P. N. S. Roy 2015 Geomatics, Natural Hazards, and Risk 6 2 133, 140 10.1080/19475705.2013.820797 2015GNHR....6..131G free Earthquake Six three-axis accelerometers that were within 60 km on captured the event, including two units that were close to the projection of the fault at the surface. Analysis of the data recorded by these devices revealed the distribution of slip, moment release over time, and the location of the maximum slip. The mechanism of the event was typical of the thrust system of the Himalayas, with maximum slip (1.5 m on) occurring to the west and southwest of the hypocenter. Energy release began slowly and built to a crescendo four seconds after the initiation of the rupture.Rupture history and seismotectonics of the 1991 Uttarkashi, Himalaya earthquake F. Cotton M. Campillo A. Deschamps B. K. Rastogi 1991 Tectonophysics 258 1–4 35–51 10.1016/0040-1951(95)00154-9 1996Tectp.258...35C thumb|USGS ShakeMap for the event Damage Scientists from the Indian Institute of Technology Kanpur (IITK) conducted a survey of the affected areas between 27 October and 4 November. Their work revealed that more than 300,000 people in 1,294 villages were affected by the shock. Stone masonry homes (that usually supported heavy roofs) fared badly in areas where high intensity shaking occurred. The United States' National Geophysical Data Center indicates that 7,500 homes were damaged and another 7,500 were destroyed while the IITK report shows that up to 42,400 houses were damaged.Garhwal Earthquake of Oct. 20, 1991 http://www.nicee.org/eqe-iitk/uploads/EQR_Uttarkashi.pdf Sudhir. K. Jain Ramesh P. Singh Vinay K. Gupta Amit Nagar 1992 National Information Centre of Earthquake Engineering EERI Special Earthquake Report 26 2 1–3 The United States' National Geophysical Data Center and the Belgian Centre for Research on the Epidemiology of Disasters' EM-DAT database both list 1,500 fatalities for the event with EM-DAT also listing 1,383 injuries. The USGS's Preliminary Determination of Epicenters and the Utsu catalog both list 2,000 deaths and 1,800 injured. Intensity Earthquake zones of India Jain Singh Gupta Nagar 1992 stated that the shock was generally moderate while further clarifying the intensities that were observed at specific locations. Ghansyali, Gongotri, and Tehri were listed as experiencing intensity VII (Very strong) shaking and Bhatwari, Budhakedar, Krishanpur, Mahinanda, Maneri, and Uttarkashi were listed as experiencing intensity VIII (Severe) shaking. In a report that documented the study of strong motion recordings of the event, Jain Das 1993 clarified that while Bhatwari and Uttarkashi experienced intensity VIII shaking at distances of 25 km on and 40 km on respectively, there was a small 20 km square mile area that experienced a maximum intensity of IX (Violent).Analysis of Strong Motion Records from Uttarkashi Earthquake for Assessment of Code Provisions for Different Seismic Zones http://www.iitk.ac.in/nicee/skj/Research_Papers/ANALYSIS%20OF%20STRONG%20MOTION%20RECORDS%20FROM%20UTTARKASHI_39.pdf Sudhir K. Jain Satrajit Das 1993 Earthquake Spectra 9 4 739, 742 10.1193/1.1585738 1993EarSp...9..739J 128901914 See also List of earthquakes in 1991 List of earthquakes in India 1999 Chamoli earthquake Tehri Dam References ISC-GEM Global Instrumental Earthquake Catalogue (1900–2012) http://www.isc.ac.uk/iscgem/index.php ISC 2016 International Seismological Centre Version 3.0 Significant Earthquake Database https://www.ngdc.noaa.gov/nndc/struts/form?t=101650&s=1&d=1 https://web.archive.org/web/20060929000601/http://www.ngdc.noaa.gov/nndc/struts/form?t=101650&s=1&d=1 dead 29 September 2006 National Geophysical Data Center / World Data Service (NGDC/WDS) National Geophysical Data Center, NOAA 10.7289/V5TD9V7K 1972 Data Set PAGER-CAT Earthquake Catalog https://earthquake.usgs.gov/static/lfs/data/pager/catalogs/PAGER_CAT_v2.zip 4 September 2009 United States Geological Survey Version 2008_06.1 Precursor seismicity, foreshocks and aftershocks of the Uttarkashi earthquake of October 20, 1991 at Garhwal Himalaya J. R. Kayal 2015 Tectonophysics 263 1–3 339 10.1016/S0040-1951(97)81488-6 1996Tectp.263..339K Further reading Seismotectonics of the 20 October 1991 Uttarkashi earthquake in Garhwal, Himalaya, North India http://cat.inist.fr/?aModele=afficheN&cpsidt=4032621 V. C. Thakur K. Sushil 1994 Terra Nova 6 1 90–94 10.1111/j.1365-3121.1994.tb00637.x 1994TeNov...6...90T subscription The Uttarkashi earthquake of 20 October: Implications and lessons Valdiya K. S. Current Science 1991 61 12 801–803 24095349 External links M 6.8 – Uttaranchal, India – United States Geological Survey The Great Himalayan Earthquakes – Himalayan Journal 317038 Uttarkashi Earthquake, 1991 Uttarkashi Category:Disasters in Uttarakhand Category:Earthquakes in India Category:History of Uttarakhand (1947–present) Category:October 1991 in India Category:Uttarkashi district Category:1990s in Uttar Pradesh