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ChEESE Pilot on Physics-Based Tsunami-Earthquake Interaction: Paper on 3D Acoustic-Elastic Coupling with Gravity Accepted for SC21 Conference
29 June 2021
3D fully coupled acoustic-elastic model

3D fully coupled acoustic-elastic simulation of the 2018 Sulawesi earthquake and tsunami in Palu Bay: (a) map view of the vertical sea surface velocity (b) sea surface height of the initiated tsunami (after 60s), (c) 3D view of earthquake and tsunami model, (d) sea surface displacement directly after the earthquake.

 

ChEESE partners LMU and TUM, in collaboration with researchers from Stanford University, USA, successfully performed the first petascale production runs and scaling studies for the ChEESE pilot demonstrator on physics-based tsunami-earthquake interaction on several supercomputers - SuperMUC-NG, Shaheen, Mahti and Frontera. The respective pilot demonstrator develops a new model to study how tsunamis are generated, starting from the dynamic earthquake rupture process along systems of faults via the generation and propagation of elastic, acoustic and gravitational waves in complex solid earth and ocean models up to the generation and propagation of tsunami waves. LMU and TUM developed a 3D fully coupled elastic-acoustic and gravity wave propagation solver in the earthquake simulation software SeisSol, building upon 2D approaches developed by the Stanford group. In a "landmark" simulation they perform the first fully coupled simulation of an actual earthquake-tsunami event: the 2018 Sulawesi earthquake and subsequent tsunami in the Palu Bay. The respective suprising and devastating tsunami, reaching run-up heights of more than 9m in the Bay, resulted from a strike-slip earthquake, which is producing predominately horizontal displacements of the ocean floor.  Nevertheless, recent simulations using 2D tsunami shallow water modes suggested that the Palu tsunami can be primarily understood from the complex interaction of earthquake rupture and the complex 3D structure of the Bay. Our new fully-coupled elastic-acoustic model further confirms this explanation and establishes a novel method for solving an entirely new class of earthquake-tsunami problems.

Simulations were executed with up to 261 billion degrees of freedom. The largest simulation ran for 5.5 hours on 3,072 nodes of the SuperMUC-NG supercomputer, installed at the Leibniz Supercomputing Centre, achieving a sustained performance of 3.1 PFLOPS.  Further studies to evaluate the parallel scalability of the new SeisSol model were executed on the supercomputers Mahti, Shaheen-II and Frontera. As part of a collaboration with the Texas Advanced Computing Center, scalability was tested on up to 7000 compute nodes, maintaining excellent parallel efficiency. 

The respective work has been accepted and will be presented at the SC21 Supercomputing Conference in November 2021: 

Lukas Krenz, Carsten Uphoff, Thomas Ulrich, Alice-Agnes Gabriel, Lauren S. Abrahams, Eric M. Dunham, Michael Bader: "3D Acoustic-Elastic Coupling with Gravity: The Dynamics of the 2018 Palu, Sulawesi Earthquake and Tsunami".