Strong-Motion Simulation of the 1988 Indo-Burma and Scenario Earthquakes in NE India by Integrating Site Effects in a Semi-Empirical Technique

Abstract

This study focuses on the validation and applicability of a recently modified semi-empirical technique (MSET) to integrate site effects. The improvement of MSET by considering site effects has been verified by the data of the 1988 Indo-Burma earthquake (Mw 7.2), which happened in the North Eastern Region (NER) in India. This technique is also used to model a future scenario earthquake (Mw 8.2) in the NER. The required site effects are estimated using Nakamura’s horizontal-to-vertical (H/V) ratio technique for 89 waveform records. The obtained site effects are further used to modify an existing semi-empirical technique. To validate this modification, the strong-motion records of the 1988 Indo-Burma earthquake are simulated for bedrock and surface conditions. Afterwards, the root mean square error (RMSE) of these records is compared with surface records obtained by 14 seismic stations. The records simulated at the surface are well validated well with observed ones as compared to the records simulated at bedrock and hence confirm the reliability of the MSET. The improved performance of the MSET after incorporation of site effects validates the approach of the present work and will prove to be significant for simulation of earthquake surface conditions in any region. Further, this improved MSET is used to simulate strong-motion records of a future scenario earthquake (Mw 8.2) with the same epicentral location. The iso-acceleration maps are prepared from simulated records for both cases (Mw 7.2 and 8.2), which provide peak ground acceleration (PGA) values of more than 500 and 1000, respectively, for near-field regions. The obtained results are of significant interest for seismic hazard assessment of NE India.