Methods to Perform Site Specific Seismic Hazard Assessment

Abstract

This dissertation, titled "Methods to Perform Site Specific Seismic Hazard Assessment," presents a comprehensive workflow for evaluating earthquake hazard through both deterministic and probabilistic approaches. Focusing on the Saraighat Bridge site in Guwahati, Assam, the study details the collection and homogenization of regional earthquake data, declustering procedures, and assignment of seismicity parameters to multiple fault sources via the Gutenberg-Richter relationship. Deterministic Seismic Hazard Analysis (DSHA) utilizes region-specific ground motion prediction equations to estimate conservative peak ground acceleration (PGA) values for each fault scenario, while Probabilistic Seismic Hazard Analysis (PSHA) quantifies the combined uncertainties and effects of all relevant seismic sources, generating hazard curves and uniform hazard spectra (UHS) across varied exceedance probabilities and design periods. The analysis demonstrates notable faultspecific hazard variability, with the Oldham Fault emerging as the controlling source for design-level ground motions at the study site. By benchmarking results against regional codes and prior studies, the research emphasizes the necessity of meticulous site-specific procedures for robust, performancebased seismic design in high-risk regions. The established methodology supports resilient infrastructure planning and enhanced seismic risk mitigation for critical facilities in Northeast India.