  Tectonic deformation crucially shapes the Earth's surface, with strain
localization resulting in the formation of shear zones and faults that
accommodate significant tectonic displacement. Earthquake dynamic rupture
models, which provide valuable insights into earthquake mechanics and seismic
ground motions, rely on initial conditions such as pre-stress states and fault
geometry. However, these are often inadequately constrained due to
observational limitations. To address these challenges, we develop a new method
that loosely couples 3D geodynamic models to 3D dynamic rupture simulations,
providing a mechanically consistent framework for earthquake analysis. Our
approach does not prescribe fault geometry but derives it from the underlying
lithospheric rheology and tectonic velocities using the medial axis transform.
We perform three long-term geodynamics models of a strike-slip geodynamic
system, each involving different continental crust rheology. We link these with
nine dynamic rupture models, in which we investigate the role of varying
fracture energy and plastic strain energy dissipation in the dynamic rupture
behavior. These simulations suggest that for our fault, long-term rheology, and
geodynamic system, a plausible critical linear slip weakening distance falls
within Dc in [0.6,1.5]. Our results indicate that the long-term 3D stress field
favors slip on fault segments better aligned with the regional plate motion and
that minor variations in the long-term 3D stress field can strongly affect
rupture dynamics, providing a physical mechanism for arresting earthquake
propagation. Our geodynamically informed earthquake models highlight the need
for detailed 3D fault modeling across time scales for a comprehensive
understanding of earthquake mechanics.
