S T G Raghukanth

In this paper, variation of ground motion for Imphal city with respect to synthetically generated 10 samples of earthquake (Mw 8.1) that occurred in Indo-Burmese subduction zone (very near to Imphal) is presented based on finite-fault seismological model combined with equivalent linear site response analyses. For all 10 sample earthquake events, mean and standard deviation of surface level spectral ground acceleration at peak ground acceleration (PGA) and natural periods of 0.3 and 1 s have been reported in the form of contour maps. These maps can be used as first hand information for administration, engineers, and planners to identify vulnerable areas of Imphal city.

Himachal Pradesh has experienced several major earthquakes in the past and this high seismicity can be attributed to the under-thrusting of the Indian tectonic plate against the Asian plate. Multi-channel Analysis of Surface Waves tests (MASW) were carried out at 73 test sites, located in 22 important cities, which indicated that the test sites were of C and D types. The ground motion prediction equations capable of predicting the surface level ground motion for these site conditions have been developed in line with the Probabilistic Seismic Hazard Analysis (PSHA) methodology of NDMA report (2011) by incorporating the evaluated site response functions. The probable seismic sources were identified from the Seismotectonic Atlas of India published by GSI (2000) and the recurrence parameters were established from the earthquake catalogue of Raghukanth (Bull Earthq Eng 9:1361-1386, 2011). The surface level peak ground acceleration (PGA) was estimated by PSHA approach for a return period of 2,475 year that corresponds to a 2 % probability of exceedance during a design life of 50 years. Also, the uniform hazard response spectrum plots for some important test cities are presented. The predictions of the developed GMPE agrees well with the seismic events recorded in this region.