Type of publication
Article in journal
Year of publication
Ulrich, T., Gabriel, AA. & Madden, E.H. Stress, rigidity and sediment strength control megathrust earthquake and tsunami dynamics. Nat. Geosci. (2022). https://doi.org/10.1038/s41561-021-00863-5
Megathrust faults host the largest earthquakes on Earth, which can trigger cascading hazards such as devastating tsunamis. Determining characteristics that control subduction-zone earthquake and tsunami dynamics is critical to mitigate megathrust hazards but is impeded by structural complexity, large spatio-temporal scales and scarce or asymmetric instrumental coverage. Here we use high-performance computing multi-physics simulations to show that tsunami genesis and earthquake dynamics are controlled by along-arc variability in regional tectonic stresses together with depth-dependent variations in rigidity and yield strength of near-fault sediments. We aim to identify dominant regional factors controlling megathrust hazards. To this end, we demonstrate how to unify and verify the required initial conditions for geometrically complex, multi-physics earthquake–tsunami modelling from interdisciplinary geophysical observations. We present large-scale computational models of the 2004 Sumatra–Andaman earthquake and Indian Ocean tsunami that reconcile near- and far-field seismic, geodetic, geological, and tsunami observations and reveal tsunamigenic trade-offs between slip to the trench, splay faulting and bulk yielding of the accretionary wedge. Our computational capabilities render possible the incorporation of present and emerging high-resolution observations into dynamic-rupture-tsunami models and will be applicable to other large megathrust earthquakes. Our findings highlight the importance of regional-scale structural heterogeneity to decipher megathrust hazards.