Dynamic Rupture Modeling of Large Earthquake Scenarios at the Hellenic Arc Toward Physics-Based Seismic and Tsunami Hazard Assessment

Abstract

The Mediterranean Hellenic Arc subduction zone (HASZ) has generated several $M_W\ge$8 earthquakes and tsunamis. Seismic-probabilistic tsunami hazard assessment typically utilizes uniform or stochastic earthquake models, which may not represent dynamic rupture and tsunami generation complexity. We present an ensemble of ten 3D dynamic rupture earthquake scenarios for the HASZ, utilizing a realistic slab geometry. Our simplest models use uniform along-arc pre-stresses or a single circular initial stress asperity. We then introduce progressively more complex models varying initial shear stress along-arc, multiple asperities based on scale-dependent critical slip weakening distance, and a most complex model blending all aforementioned heterogeneities. Thereby, regional initial conditions are constrained without relying on detailed geodetic locking models. Varying epicentral locations in the simplest, homogeneous model leads to different rupture speeds and moment magnitudes. We observe dynamic fault slip penetrating the shallow slip-strengthening region and affecting seafloor uplift. Off-fault plastic deformation can double vertical seafloor uplift. A single-asperity model generates a $M_W\sim$8 scenario resembling the 1303 Crete earthquake. Using along-strike varying initial stresses results in $M_W\sim$8.0–8.5 dynamic rupture scenarios with diverse slip rates and uplift patterns. The model with the most heterogeneous initial conditions yields a $M_W\sim$7.5 scenario. Dynamic rupture complexity in prestress and fracture energy tends to lower earthquake magnitude but enhances tsunamigenic displacements. Our results offer insights into the dynamics of potential large Hellenic Arc megathrust earthquakes and may inform future physics-based joint seismic and tsunami hazard assessments.