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3D Acoustic-elastic Coupling with Gravity: The Dynamics of the 2018 Palu, Sulawesi Earthquake and Tsunami

While tsunamis occur due to abrupt vertical perturbations to the water column, a devastating tsunami was caused by the strike-slip, supershear 2018, Palu, Sulawesi earthquake. Studying such surprising earthquake-tsunami behavior has been hampered by the necessity of making approximations in the fluid-solid coupling. Recent simulations (Ulrich et al., 2019) suggest that the Palu tsunami can be primarily understood from the complex interaction of transtensional earthquake rupture dynamics across a geometrically complex strike-slip fault system and the 3D bay bathymetry. However, the standard practice of linking a 3D earthquake simulation, conducted without a water layer, to a 2D tsunami shallow water model simplifies the interaction between the ocean floor and water column.

We develop a highly scalable 3D fully-coupled Earth and ocean model of earthquake rupture and tsunami generation implemented in SeisSol (Krenz et al., 2021). We model seismic, acoustic and surface gravity wave propagation sourced by physics-based non-linear earthquake dynamic rupture, naturally capturing tsunami dispersion and related nonhydrostatic effects during both tsunami generation and propagation. Multi-petascale simulations, with excellent performance on three different supercomputers, allow to include complicated geometries, such as high-resolution bathymetry, coastlines and segmented earthquake faults. We present the first fully coupled simulation of an actual earthquake-tsunami event and a 3D benchmark problem of tsunami generation by a megathrust dynamic earthquake rupture. There are notable differences in the fully coupled and 3D-2D linked models for the Palu event, potentially due to the non-hydrostatic ocean response and the complex, high-frequency source. Our work enables us to capture the entire dynamics of this process in an efficient, unified 3D model and our predictions of pressure changes in the water column, including at the seafloor, may help to interpret ocean bottom pressure sensor data containing more than just tsunami waves.

Session: Frontiers in Earthquake and Tsunami Science - Model Integration, Recent Advances, Ongoing Questions

Type: Oral

Room: Grand C

Date: 4/22/2022

Presentation Time: 09:00 AM Pacific

Presenting Author: Alice-Agnes Gabriel

Student Presenter: No

Additional Authors