Deterministic Seismic Hazard Analysis of Sree Padmanabhaswamy Temple, Kerala State

Abstract

Deterministic seismic hazard analysis (DSHA) is a technique employed to estimate potential hazards and ground shaking resulting from specific earthquake scenarios at a given location. In the present study, DSHA is conducted for the Sree Padmanabhaswamy Temple, situated in the southernmost district of Kerala, India. This seismic hazard study is crucial due to the temple’s proximity to seismic events such as the 1900 AD Coimbatore earthquake with a magnitude of 6.3 M<inf>w</inf> and the 2000 Pala earthquake with a magnitude of 4.7 M<inf>w</inf>. This study examines earthquake data within a 500 km radius surrounding the Sree Padmanabhaswamy Temple in Thiruvananthapuram District, Kerala, from 1819 to 2022 AD. The seismic zone of the temple site is III according to the Indian zonation map (IS 1893 (Part 1): 2016), relying on past earthquakes recorded throughout India. The collected earthquake data underwent a homogenization process to determine the moment magnitude (M<inf>w</inf>), distinguishing foreshocks and aftershocks from the main shocks. A seismotectonic map was developed comprising of geological discontinuities and 316 earthquakes events with moment magnitudes between 3.0 and 6.3 M<inf>w</inf>. The software tools employed for this work include MATLAB, QGIS and ZMAP. The Log-likelihood technique (LLH) was used to choose the ground motion prediction equations (GMPEs) for the location. The GMPEs were then given weights based on the computed values of the data support index (DSI). The study region was partitioned into a grid size of 0.05° × 0.05° (5 km × 5 km). Using MATLAB code, the peak ground acceleration (PGA) was estimated for the site and PGA was found in the center of each grid cell, taking into account all seismic sources within a 500 km radius. In addition, site-specific deterministic spectrum was also developed. The findings show that Sree Padmanabhaswamy Temple has low seismicity, which is defined by weak to moderate earthquakes that have sources close to the temple. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.