The Main Factors Controlling Probabilistic Seismic Hazard Variability Due to Epistemic Uncertainty in Greece: Results from a One-Factor-at-a-Time Analysis

Abstract

We present a one-factor-at-a-time (OFAT) sensitivity study for the Probabilistic Seismic Hazard Assessment (PSHA) in Greece. The analysis examines several PSHA controlling factors, such as seismic source model (geometry, etc.), active tectonics (faulting type, etc.), as well as the employed ground-motion prediction equations (GMPEs). We have considered only peak ground acceleration (PGA) and peak ground velocity (PGV) for a typical PSHA scenario (10% probability of exceedance in 50 yr). OFAT results are presented using Tornado diagrams for 42 major urban centers of Greece that cover the study area revealing regions of different PSHA uncertainty. In general, the most critical factors controlling PSHA uncertainties are the Gutenberg–Richter (G-R) parameters (a and b), as well as the employed GMPE. However, significant spatial variability of these factors is observed with large differences between high- and low-seismicity regions, as well as between PGA and PGV. The results not only provide an objective assessment of the variability of PSHA uncertainties but also verify the need for additional work to minimize epistemic PSHA uncertainties, focusing on the most critical factors that control PSHA.