Modeling ground motions and crustal deformation from tsunami earthquakes: Rupture parameter constraints from the 2010 Mentawai event

We use a combination of near-field simulated and observational data to constrain the rise time, rupture velocity, and high frequency stress parameter for the 2010 M7.8 Mentawai tsunami earthquake. Tsunami earthquakes, which are shallow-rupturing events generating exceptionally large seafloor displacements, are challenging for current tsunami early warning systems. A combination of near-field high-rate GNSS and seismic data can be used for early-discrimination, but the dearth of data from these events limits testing of such an implementation in a real-time scenario. In lieu of near-field data, models with realistic rupture physics can be leveraged to improve local tsunami warning. We develop recommendations for such parameters based on observations of near-field data from the 2010 M7.8 Mentawai earthquake. We find that rise time and rupture velocity covary, and that rise time–rupture velocity combinations ranging from 5.4 s–1.23 km/s to 12 s–1.6 km/s adequately model the long duration of the Mentawai event. We find that a stress parameter of 1.43 MPa best models the high frequency deficiency. We present equations which can be used to determine reasonable parameter values for simulating tsunami earthquakes, and we find that simulated data generated with the recommended parameters capture defining characteristics of tsunami earthquakes. Correction (January 2025): When originally published, the title of this article was incorrectly printed in the PDF version. Seismica regrets the error. Also, HR-GNSS data from Earth Observatory of Singapore, Nanyang Technological University (EOS-NTUS) was mistakenly attributed to Badan Informasi Geospasial (BIG). The authors regret the error.