Impact of rupture-plane uncertainty on earthquake hazard: observations from the 30 october 2020 Samos earthquake

We assess the significance of rupture-plane uncertainty in the estimated ground-motion intensity measures (IMs) by using the centroid moment-tensor and fault-plane solutions as well as the ground-motion recordings of the 30 October 2020 Samos Earthquake. We sampled ground-motion fields using stochastically generated rupture planes by considering the uncertainties imposed from alternative fault-plane solutions to reach our objective. Our observations indicate that the compromise between rupture-plane uncertainty and variability in the predicted ground-motion IMs depends on the modeling complexity of the ground-motion predictive model (GMPM). It also depends on the spatial location of the site relative to the ruptured fault. This conclusive remark is important for modelers who perform regional or site-specific seismic hazard and risk analyses. The presented case studies are also useful for GMPM developers because the ground-motion models contain predictor parameters, the most ubiquitous one is source-to-site distance, that are affected from rupture-plane geometry. Depending on the level of model complexity, the number of predictor parameters affected from rupture-plane geometry can increase and therefore the estimated ground-motion IMs can become more prone to rupture-plane uncertainty. Confined to our case-specific observations, we intend to make some suggestions to hazard, risk, and GMPM modelers for the consideration of rupture-plane uncertainty at the end of the paper.