An Integrated Uncertainty Quantification Framework for Probabilistic Seismic Hazard Analysis

AbstractProbabilistic seismic hazard analysis (PSHA) is a tool to quantify the annual rate of exceedance of seismic intensity measure at a location of interest. The present study investigates the uncertainty embedded in three PSHA parameters: magnitude of earthquake, source-to-site distance, and corresponding ground shaking. Although previous researchers have worked to quantify the uncertainty in these hazard parameters, the source-to-site distance uncertainty in PSHA has not been explicitly addressed to acquire more accurate and reliable seismic hazard estimates. This study develops an uncertainty quantification framework for PSHA considering source-to-site distance uncertainty, including interdependency between hazard parameters. To capture this uncertainty, an approach of considering grids in the area seismic source zone is adopted using a geographic information system (GIS) and implementing Latin hypercube sampling (LHS) to quantify the uncertainty of the occurrence of an earthquake at any distance from the site. The interaction of magnitude and source-to-site distance has been investigated using copula theory. As a part of practical implementation, PSHA of Silchar city in Northeast India is taken into consideration due to its tectonic features and high seismicity. This work applies two processes to quantify uncertainty: (1) considering the center point of a grid, and (2) stratified sampling of points within a grid by LHS. The results reveal that on applying LHS (with uncorrelated random events), the hazard increases due to discretization of the area sources, and robust consideration of uncertainty. While, in case of correlated random events, the hazard levels are relatively low. The results are being subjected to verification and are compared with the previous studies to ensure fulfilling specifications and its intended purpose. Structural designers and decision makers can utilize the developed PSHA framework to plan and build new projects and to evaluate the seismic risk of existing infrastructure in a city.