Publication

Abstract : North-East India is located in one of the most seismic prone areas of the world. India has faced several devastat-ing earthquakes in the past. The largest of these have originated in the Himalayan plate boundary region, which has remained a region of great scientific and engineering interest. In spite of this, very little seismological information is available about North- East India, which is the focus for present study. Only few attenuation relationships are availa-ble for this region, which are most valuable in a region where too much strong motion recordings are not available. However in recent time, with the inception of 300 strong motion instruments under Indian National Strong Motion Network deployed under Mission Mode project (Government of India), a good quality of strong motion data became available. Taking the advantage of data collected by this network and earlier analogue strong motion arrays, an en-deavor has been made to develop an empirical attenuation relationship for peak horizontal ground accelerations for North-East Himalayan region in India. The data set consists of 216 peak ground horizontal accelerations from 24 earthquakes (4.0≤M≤6.8) recorded by strong-motion arrays and National Strong Motion Network project in India. The present analysis uses a two-step stratified regression model. The estimated attenuation relationship for the region is ( ) ( ) Where A is the peak ground acceleration (g), M is the magnitude, and X is the hypocentral distance from the source. The residual sum of squares is 0.1451. The obtained Empirical attenuation relationship will provide better insight for site specific studies as well as for hazard estimation for North-East Himalayan region. Attenuation rela-tionships for expected peak ground acceleration (g) have been presented for magnitudes 5, 6, 7 and 8 for North-East Himalayan region.