Dynamic Rupture Modeling of the 2010 Mw 7.8 Mentawai Tsunami Earthquake with Self-Similar Stress Drop and Wedge Inelasticity

We model the 2010 Mw 7.8 Mentawai tsunami earthquake using dynamic rupture simulations with heterogeneous, self-similar stress drop following a 1/k spatial spectrum. Rupture is confined to ~40 km of the deformation front based on high-rate GPS data, with stress and pore-pressure conditions defined by a three-dimensional critical wedge solution, a hypocentral depth of 10 km, and a constant fault dip of 4° from marine geophysical surveys. Random stress drop is implemented through dynamic friction, allowing natural incorporation of inelastic wedge deformation. With minimal tuning, elastic and inelastic models fit the GPS data comparably well, indicating that geodetic observations primarily constrain rupture extent. Inelastic wedge deformation produces >5 m of seafloor uplift despite reduced shallow slip—over three times that of elastic models—and is amplified by shallow slip strengthening via increased fault shear stress. This mechanism explains the disproportionate tsunami generated by the Mentawai earthquake, is consistent with pop-up structures observed in marine reflection data, and highlights the importance of including wedge inelasticity in probabilistic seismic and tsunami hazard assessments in global accretionary margins.