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Nat Hazards (2010) 53:443457 DOI 10.1007/s11069-009-9439-3
ORIGINAL PAPER
A. K. Mahajan V. C. Thakur Mukat Lal Sharma Mukesh Chauhan
Received: 5 March 2008 / Accepted: 20 July 2009 / Published online: 27 August 2009 Springer Science+Business Media B.V. 2009
Abstract The seismically active Northwest (NW) Himalaya falls within Seismic Zone IV and V of the hazard zonation map of India. The region has suffered several moderate (*25), large-to-great earthquakes (*4) since Assam earthquake of 1897. In view of the major advancement made in understanding the seismicity and seismotectonics of this region during the last two decades, an updated probabilistic seismic hazard map of NW Himalaya and its adjoining areas covering 2834N and 7482E is prepared. The northwest Himalaya and its adjoining area is divided into nineteen different seismogenic source zones; and two different region-specic attenuation relationships have been used for seismic hazard assessment. The peak ground acceleration (PGA) estimated for 10% probability of exceedance in 50 and 10 years at locations dened in the grid of0.25 9 0.25. The computed seismic hazard map reveals longitudinal variation in hazard level along the NW Himalayan arc. The high hazard potential zones are centred around Kashmir region (0.70 g/0.35 g), Kangra region (0.50 g/0.020 g), Kaurik-Spitti region(0.45 g/0.20 g), Garhwal region (0.50 g/0.20 g) and Darchula region (0.50 g/0.20 g) with intervening low hazard area of the order of 0.25 g/0.02 g for 10% probability in 50 and 10 years in each region respectively.
Keywords Seismic Hazard Probabilistic 1905 Kangra earthquake
Seismotectonics Northwest Himalaya
1 Introduction
The Himalaya is a result of continentcontinent collision between the Indian and the Eurasian plates. Since collision during *55 Ma, India has been under-thrusting Asia (Tibet) at a rate of 4550 mm/year (Besse and Courtillot 1988; Dewey et al. 1989). The
A. K. Mahajan (&) V. C. Thakur M. Chauhan
Wadia Institute of Himalayan Geology, 33, GMS Road, Dehradun, India e-mail: [email protected]
M. L. Sharma
Indian Institute of Technology Roorkee, Rookree, India
Probabilistic seismic hazard map of NW Himalaya and its adjoining area, India
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GPS measurements indicates that India is moving northeast at a convergence rate of 55 mm/year, of which 1822 mm/year is accommodated within the Himalaya (Bilham et al. 1997), and the remaining convergence...