Linked and fully coupled 3D earthquake dynamic rupture and tsunami modeling for the Húsavík-Flatey Fault Zone in North Iceland

• Published in: Solid Earth
• Main Authors: Kutschera, Fabian, Gabriel, Alice Agnes, Wirp, Sara Aniko, Li, Bo, Ulrich, Thomas, Abril, Claudia, Halldórsson, Benedikt
• Other Authors: Physical Science and Engineering (PSE) Division, Institute of Geophysics, Department of Earth and Environmental Sciences, Ludwig Maximilian University, Munich, Germany, Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA, GEOMAR, Helmholtz Centre for Ocean Research, Kiel, Germany, Barcelona Supercomputing Center, Barcelona, Spain, Division of Processing and Research, Icelandic Meteorological Office, Reykjavík, Iceland, Faculty of Civil and Environmental Engineering, School of Engineering and Natural Sciences, University of Iceland, Reykjavík, Iceland
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Copernicus GmbH 2024
• Subjects: Akureyri; Húsavík; Iceland; Ólafsfjörður; Flatey; Hrísey
• Online Access: http://hdl.handle.net/10754/697590; https://doi.org/10.5194/se-15-251-2024

Tsunamigenic earthquakes pose considerable risks, both economically and socially, yet earthquake and tsunami hazard assessments are typically conducted separately. Earthquakes associated with unexpected tsunamis, such as the 2018 Mw7.5 strike-slip Sulawesi earthquake, emphasize the need to study the tsunami potential of active submarine faults in different tectonic settings. Here, we investigate physics-based scenarios combining simulations of 3D earthquake dynamic rupture and seismic wave propagation with tsunami generation and propagation. We present time-dependent modeling of one-way linked and 3D fully coupled earthquakes and tsunamis for the 1/4100km long Húsavík-Flatey Fault Zone (HFFZ) in North Iceland. Our analysis shows that the HFFZ has the potential to generate sizable tsunamis. The six dynamic rupture models sourcing our tsunami scenarios vary regarding hypocenter location, spatiotemporal evolution, fault slip, and fault structure complexity but coincide with historical earthquake magnitudes. Earthquake dynamic rupture scenarios on a less segmented fault system, particularly with a hypocenter location in the eastern part of the fault system, have a larger potential for local tsunami generation. Here, dynamically evolving large shallow fault slip (1/48m), near-surface rake rotation (±20), and significant coseismic vertical displacements of the local bathymetry (±1m) facilitate strike-slip faulting tsunami generation. We model tsunami crest to trough differences (total wave heights) of up to 1/40.9m near the town Ólafsfjörður. In contrast, none of our scenarios endanger the town of Akureyri, which is shielded by multiple reflections within the narrow Eyjafjörður bay and by Hrísey island. We compare the modeled one-way linked tsunami waveforms with simulation results using a 3D fully coupled approach. We find good agreement in the tsunami arrival times and location of maximum tsunami heights. While seismic waves result in transient motions of the sea surface and affect the ocean response, they do not ...