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 Mw>=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 hypocenter
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 Mw~8 scenario
resembling the 1303 Crete earthquake. Using along-strike varying initial
stresses results in Mw~8.0-8.5 dynamic rupture scenarios
with diverse slip rates and uplift patterns. The model with the most
heterogeneous initial conditions yields a Mw~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.