Deep soil seismic hazard assessment: analyzing the impact of local site effects by stochastic site response analysis—a comparative approach

Incorporating local site effects into seismic hazard analysis, especially for deep soil sites, is crucial. This study describes probabilistic seismic hazard analysis (PSHA) incorporating site effects for a deep soil site in Pakistan. Bedrock hazard is assessed in FRISK88M using a rigorous logic tree. Equivalent linear site response analysis (SRA) is performed in STRATA and captured the soil variability properties via Monte Carlo simulations. We proposed a hybrid approach in this study which utilizes the outcomes of Random Vibration Theory (RVT) and multiple Time Histories (TH) approach to assess the site-specific amplifications. Incorporating site amplifications transforms rock ground motion models into site-specific then we performed soil PSHA in FRISK88M. The analysis revealed that RVT overpredicts (3–17%) while TH underpredict (1–6%) hazard as compared to the hybrid approach at all return periods. The hybrid approach proposed in this study provides an innovative, effective and reliable estimates.