Dynamics of mega earthquakes and tsunamis unraveled

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Earth's strongest earthquakes occur in so-called subduction zones, where one Earth plate dives beneath another and megathrust faults occur. Despite major advancements in earthquake monitoring and warning systems, earth scientists struggle to predict large earthquakes, especially tsunami generating subduction events, because relatively little data exists. LMU geophysicists Thomas Ulrich and Alice-Agnes Gabriel, in collaboration with Elizabeth Madden (University of Brasília), have now identified three key regional factors that control earthquake dynamics and the potential for large tsunami generation at subduction zones.

The researchers analyzed cutting-edge, multi-physics simulations of the 2004 Sumatra-Andaman earthquake and tsunami using the powerful supercomputer SuperMUC-NG in Garching, Germany. The simulations incorporated data on long-term plate tectonic movements as well as first-order physical laws of how rocks break and slide. The study is the first unified and physics-based model able to explain the physical processes during this earthquake’s rupture as well as the growth and propagation of the tsunami, which was up to 30 meters high. Importantly, the earthquake model accounts for complex fault geometry and variations in rock behavior near these faults in three-dimensions. The results revealed that that subduction earthquake dynamics and tsunami genesis are controlled by spatial variation in the tectonic forces, as well as by the stiffness and strength of local rocks. According to the authors, the study could help to improve the prediction of earthquakes and tsunamis in the future.

Thomas Ulrich, Alice-Agnes Gabriel & Elizabeth H. Madden: Stress, rigidity and sediment strength control megathrust earthquake and tsunami dynamics. Nature Geoscience 2022