Sensitivity of Probabilistic Seismic Hazard Results to Epistemic Uncertainties Related to Seismic Source Characterization
摘要
This paper investigates the impact of epistemic uncertainties in seismic source characterization (SSC) on hazard results through a probabilistic seismic hazard analysis (PSHA) study conducted for a site in Turkey. The seismicity of the study region is represented by area and fault source models, with epistemic uncertainty in the SSC reflected in a logic tree structure. Hazard results are analysed by decomposing the overall mean hazard into contributions from individual earthquake sources. Sensitivity analyses are also conducted, including the plotting of Tornado diagrams at various annual exceedance rates. The results indicate that hazard results are highly sensitive to epistemic uncertainties associated with sources located in close proximity and characterized with high activity rates and large maximum magnitudes (Mmax). For area sources near the site, the style of faulting is one of the most influential parameters. Depending on the faulting style, dip angle and strike also play a significant role in hazard results. Uncertainties associated with these parameters may lead to substantial deviations from the mean hazard estimates, with variations reaching up to 20%. Based on these observations, a set of recommendations is provided in the Summary and Conclusions section for potential simplifications in the logic tree structure of seismic source characterization. These suggestions align with the application of a graded approach as per IAEA standards.