Probabilistic Seismic Hazard Assessment of Palghar District, Maharashtra, India by Considering Spatially Nonuniform Seismicity

Abstract

The Palghar district of Maharashtra has recently received attention because of frequent occurrences of earthquakes in its vicinity in the last few years since November 2018. The district falls under seismic zone III, as per the seismic zonation map of India. As the recent earthquake activities have been preceded by many major seismic events in the region, it necessitates to re-evaluate the level of seismic hazard of the area in a reliable and realistic way. With this aim in mind, the probabilistic seismic hazard map of Palghar district with regard to Peak Ground Acceleration (PGA) and 5% damped pseudo-spectral acceleration (PSA) at 0.2 and 1.0 s for 10% and 2% probability of exceedance (PoE) in 50 years at engineering bedrock level is presented. The estimation of hazard is performed in a finer grid resolution of 0.02° × 0.02° and takes into consideration the nonuniform distribution of earthquake probability within a seismic source zone (SSZ) and data-driven selection of suitable ground motion prediction equations (GMPEs) with appropriate weight factors. The spatial variation of the hazard level as reflected in the hazard maps, demonstrates notable improvements over the earlier studies. The PGA at the atomic power plant in the district is found to be 0.15g for DBE condition. The results can be used for designing earthquake-resistant structures in addition to assessing seismic safety of the existing structures.

Keywords

log-likelihood / probabilistic seismic hazard / smooth gridded seismicity / suitability of GMPEs

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