Preliminary Seismic Hazard Map of Peninsular India

Abstract

This paper presents the preliminary seismic hazard assessment of the peninsular India (lat. 10-26N and long. 68-90E) which is considered to be seismically most stable land masses of the Indian plate. Past major seismic events in this region (Koyna, 10 Dec 1967; Bhadrachalam, 13 Apr 1969; Hyderabad, 30 Jun 1983; Latur, 30 Sep 1993; Jabalpur, 22 May 1997; Bhuj, 26 Jan 2001) clearly shows that the seismicity of the area is highly varying. There were five damaging earthquakes with magnitudes Mw 6.0 occurred in this region, stressing the importance of detailed seismic hazard assessment for this region. For India, Bhatia published a probabilistic seismic hazard map based on several well identified and prominent source zones in the country. An attempt has been made in this paper to study the present seismic status of this region incorporating the detailed seismicity, tectonic and geologic characteristics. Around 110 major faults are considered in this present research study for estimating the peak ground acceleration at the bedrock level using the attenuation relationships developed by Atkinson and Boore. The considered area under peninsular region has been divided into grid pattern with 10x10 and around 280 site specific locations are considered for the detailed analysis. From this study, it is observed that 30% of PI is overestimated and 12% is underestimated when compared with PGA values for various regions provided in Indian seismic code IS: 1893-2002. The results show that there is a great need for carrying out the detailed microzonation of an area within the peninsular India.