Methods and Test Cases for Linking Physics-Based Earthquake and Tsunami Models

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Authors

Elizabeth Madden , Michael Bader, Jörn Behrens , Ylona van Dinther , Alice-Agnes Gabriel , Leonhard Rannabauer, Thomas Ulrich, Carsten Uphoff, Stefan Vater, Stephanie Wollherr

Abstract

Despite the inter-dependence of long term deformation, earthquakes and tsunamis, few modelling approaches bridge these processes. To advance the understanding of tsunami generation and earthquake-tsunami interactions, we present new methods for linking physics-based models of subduction zone geodynamics and seismic cycling, three-dimensional dynamic earthquake rupture, and tsunami generation, propagation and inundation. This modeling framework ensures mechanical consistency across temporal and spatial scales. We first present a simplified earthquake-tsunami test case, in which an earthquake rupture occurs on a planar, dipping fault surrounded by a homogeneous material and loaded by a depth-dependent stress field. This is linked to a hydrostatic tsunami model by porting the coseismic seafloor displacements. We detail the applied filters and discuss adequate spatial resolutions for this linkage. We compare tsunamis produced by two earthquake sources that vary by fault strength, and therefore slip, along the top of the fault near the seafloor. The earthquakes exhibit different rupture velocities and slip distributions, while the seafloor displacements and resulting tsunamis are more similar. This demonstrates the utility of linked models to evaluate the effects of certain earthquake characteristics on tsunami behavior. The second test case is more complex, with the initial conditions for the dynamic earthquake rupture scenario taken from a model of long term subduction zone geodynamics and seismic cycling. These conditions include the lithology, stress field, fault geometry, and fault strength, which are physically consistent with one another due to their development together over many slip events in the subduction scenario. Nucleation and rupture propagation occur spontaneously in the linked earthquake scenario. The time-dependent seafloor displacements are used to dynamically source the tsunami. We also compare this dynamically sourced tsunami with a tsunami sourced by the final, static displacements and find that the temporal variation in displacements has a clear influence on the solution. This demonstrates the utility of linked models to isolate the effects of certain modeling choices on the results. In order to encourage widespread use of these test cases, relevant materials are provided publicly. These methods facilitate research into the physical relationships between processes operating across the spatial and temporal time scales of long term deformation, earthquake rupture, and tsunami propagation.

DOI

https://doi.org/10.31223/osf.io/rzvn2

Subjects

Computer Sciences, Earth Sciences, Geology, Geophysics and Seismology, Other Computer Sciences, Physical Sciences and Mathematics

Keywords

numerical modelling, tsunami, earthquake, Geodynamics, subduction, linkage, seismic cycling

Dates

Published: 2019-09-06 14:13

Last Updated: 2020-10-27 20:54

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License

GNU Lesser General Public License (LGPL) 2.1

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