Regional Rupture-Based Seismic Hazard Analysis of Tripura State

Regional Rupture-Based Seismic Hazard Analysis of Tripura State—NE India

Anbazhagan, P. / Das, Arindam / Silas Abraham, G.

Seismic hazard analysis is the quantitative estimation of hazards caused by ground shaking at a particular site. Tripura is considered as one of the most seismically active states in India with complex seismotectonic. At the same time, detailed seismic hazard analyses with regional parameters are very less studied. So, the present study focused on estimating the deterministic seismic hazard analysis (DSHA) for Tripura considering the regional rupture characteristics and conventional approach. Seismic study area (SSA), based on regional past earthquake damages, was arrived as 700 km for the study area Tripura. A seismotectonic map was prepared for the 700 km SSA by compiling the seismic event and seismic source. Declustering of the earthquake data was done to remove the foreshocks and aftershocks, and statistical analysis was carried out for data completeness. Tripura was divided into three major seismogenic zones on the basis of seismicity and tectonic features. Seismicity parameters (a and b) were calculated using Gutenberg–Richter (G-R) relationship. All the probable seismic sources like faults, lineaments, and gaps in the study area were identified from the seismotectonic atlas (SEISAT 2000) published by Geological Survey of India (GSI) and also from the literatures available. Digitization and georeferencing of the tectonic maps were done to prepare the fault map. Using predictive ground motion equations applicable for the SSA, DSHA was carried out. The effect of the regional rupture characteristics on the seismic hazard analysis was studied by comparing the results from conventional and rupture-based hazard analysis. The maximum median Peak Ground Acceleration (PGA) values estimated in Tripura state using the rupture-based and conventional approaches were 0.50 g and 0.43 g, respectively.