Estimation of Seismic Site Coefficient and Seismic Microzonation of Imphal City, India, Using the Probabilistic Approach

Abstract

A b s t r a c t Seismic site coefficients (F s ) for Imphal city have been estimated based on 700 synthetically generated earthquake time histories through stochastic finite fault method, considering various combinations of magnitudes and fault distances that may affect Imphal city. Seismic hazard curves and Uniform Hazard Response Spectra (UHRS) are presented for Imphal city. F s have been estimated based on site response analyses through SHAKE-91 for a period range of engineering interest (PGA to 3.0 s), for 5% damping. F s were multiplied by UHRS values to obtain surface level spectral acceleration with 2 and 10% probability of exceedance in 50 year (~2500 and ~500 year) return period. Comparison between predicted mean surface level response spectra and IS-1893 code shows that spectral acceleration value is higher for longer periods (i.e., > 1.0 s), for ~500 year return period, and lower for periods shorter than 0.2 s for ~2500 year return period.

Site Coefficient of Short Fa and Long period Fv Maps Constructed from the Probabilistic Seismic Hazard Analysis in Yogyakarta Special Province

“…The estimation method in determining the seismic site coefficient has been carried out by [9]. It can be categorized as an estimation method because the exciting force used in bedrock is a synthetically generated earthquake time theory through stochastic finite-fault method.…”

“…The results showed that the Fa and Fv site coefficient obtained from the study was relatively close to the Fa and Fv written in the Code. The main aim of this study is to develop the site coefficient maps at Yogyakarta Special Province (YSP) by applying the combination of the method that has been used by [9] and [10]. In the meantime, the shear wave velocity data in YSP is not yet available therefore the VS30 data published by USGS has been used.…”