Over the last two decades, two giant tsunamis generated by megathrust earthquakes of >Mw 9 (the 2004 Sumatra–Andaman and 2011 Tohoku earthquakes) caused extensive damage to low-lying areas along the Indian Ocean and the Pacific coast of the Japanese mainland. 2016). However, the lower seafloor displacements in the blind rupture result in a smaller displaced volume of water leading to a narrower inundation corridor inland from the coast and a 15 per cent smaller inundation area overall. Davies 2019). In addition to the authors, a wide group has contributed to this effort. Use of a time-independent source in Scenarios B and C (with surface-breaching and subduction-initialized earthquakes, respectively) overpredicts run-up. 7(f) with Fig. They are linked using the integrated vertical surface velocity from the earthquake model to yield time- and space-dependent displacements to source the tsunami model, similar to methods by Saito et al. The Sunda megathrust can be divided into the Andaman Megathrust, Sumatra(n) Megathrust and Java(n) Megathrust. Here, we extend the approach that initializes a 2-D dynamic earthquake rupture with a subduction and seismic cycle model (van Zelst et al. Higher waves occur at y = 150 km, the part of the coast that is closer to locations of larger fault slip and uplift in both earthquake scenarios. In addition, such models can include physical processes non-linearly coupled to the earthquake dynamics, such as off-fault plasticity (e.g., Andrews 2005; Dunham et al. (A) Near Umnak Island, Alaska, the Pacific Plate is subducting beneath North America at 70 mm/yr (arrow). The earthquake rupture begins by forced weakening over time in a predefined patch following the nucleation procedure in several benchmarks from Harris et al. Fig. … For the blind rupture, this occurs at ∼t = 80 s, when spatial maximum is 1.9 m, the minimum is −1.0 m and the average is 0.9 m. For the surface-breaching rupture, this occurs later at ∼t = 95 s, when the spatial maximum is 2.6 m and the minimum is −1.2 m. However, the average final displacement is 0.9 m, which matches that for the blind rupture. 2019) and mixed faulting mechanisms (e.g. Also, the critical slip weakening distance Dc here varies with depth to resemble the friction drop measured during the geodynamic slip event. Temporal differences include delayed arrival at the central coast, but advanced arrival along the more distant coast and at the locations farthest inland. 2013; Roten et al. 2019b) and trade-offs with other sources. It also ensures self-consistency between those conditions and long-term subduction. including online interactive materials, The archive at https://zenodo.org/record/3836668 includes instructions and required data files to reproduce these benchmarks. Away from the centre, the run-up is lower. Due to these highly heterogeneous on- and off-fault conditions, the earthquake in this scenario has larger slip, but lower stress drop and slower rupture speed relative to the ruptures in scenarios A and B. This is also seen when comparing the tsunamis from the time-dependent sources from Scenario A versus Scenario B (Fig. 2020; Brizzi et al. Maximum run-up is increased in particular. (2009) use the 3-D, time-dependent displacements from dynamic rupture on a 3-D fault with two planar segments (megathrust and splay) as the source for shallow-water, hydrodynamic tsunami models solved with finite difference methods. Time series of sea surface height (ssh) at 3 measurement points located 10 m from the coast near x = 240 km for tsunamis sourced by the time-dependent and time-independent filtered displacements from (a) the blind rupture in Scenario A and (b) the surface-breaching rupture in Scenario B. Dynamic implications of geodynamic simulations validated with laboratory models, The seismic cycle at subduction thrusts: insights from seismo-thermo-mechanical models, Modeling the seismic cycle in subduction zones: the role and spatiotemporal occurrence of off-megathrust events, Modeling megathrust earthquakes across scales: One-way coupling from geodynamics and seismic cycles to dynamic rupture, Well-balanced inundation modeling for shallow-water flows with Discontinuous Galerkin schemes, Finite Volumes for Complex Applications VII – Elliptic, Parabolic and Hyperbolic Problems, Vol. 2011; Heidarzadeh et al. Citation Wendt, J., Oglesby, D. D., & Geist, E. L. (2009). Following Wollherr et al. 2018; Ramos & Huang 2019). How does megathrust earthquake rupture govern tsunami behaviour? Note that the general uplift is kept unchanged, while the waves characterized by high ratios of frequency to wavelength (fast propagating waves/short wavelengths) surrounding the uplift area are effectively damped. These meet the recommendations from Day et al. The three-dimensional isotropic case, Earthquake ruptures with strongly rate-weakening friction and off-fault plasticity. Search for other works by this author on: Department of Informatics, Technical University of Munich, Department of Mathematics/CEN, Numerical Methods in Geosciences, Universität Hamburg, Department of Earth Sciences, Seismology and Wave Physics, Institute of Geophysics, Department of Earth Sciences, Utrecht University, Now at: Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin, Germany, Now at: Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, Leeds, LS29JT, United Kingdom, To build the tsunami source, the time-dependent variations in the 3-D vertical and horizontal coseismic seafloor displacements are mapped into vertical perturbations of the 2-D initial bathymetry field of the tsunami model, similar to the approaches in Saito, \begin{eqnarray} Based on their magnitudes (Mw 8.5–8.6), fault area (125 km by 200 km), and slip distributions, the two earthquakes scenarios are comparable to tsunami-generating subduction zone events such as the Mw 8.5 Bengkulu earthquake that occurred off the southwestern coast of Sumatra in 2007 (Gusman et al. Devastating because: high population + nuclear power plants, megathrust earthquakes have high magnitudes, often associated with Tsunami. We study REs that reveal fault weakening after a large megathrust earthquake in Costa Rica, followed by fault recovery. Characteristics for the blind (Scenario A), surface-breaching (Scenario B) and subduction-initialized (Scenario C) dynamic earthquake rupture models. Kame et al. 2012, 2013; Galis et al. \sigma _{xy}&=& 0, \\ We use a subduction model to initialize the earthquake model in Scenario C. This approach provides reasonable earthquake initial conditions that typically are poorly constrained by data, but which exert first-order control over rupture behaviour. In the 2001 South Peru earthquake, high slip may have occurred at shallow depths, though whether or not slip occurred at the trench is inconclusive (Pritchard et al. 2019) to a 3-D dynamic earthquake rupture. Shi et al. Earthquake model results. Initially, ssh reflects the vertical displacement magnitudes from the earthquake (Fig. This results in one blind and one surface-breaching rupture that differ in fault slip distribution and rupture kinematics. In the case of the 2004 Sumatra-Andaman earthquake, recent investigations suggest that lithification of shallow sediments could permit slip at near or at the trench (Gulick et al. The fault does not intersect with the surface, so the rupture is blind, but it efficiently generates a tsunami. The third row shows temporal differences between inundation from the time-dependent and time-independent sources, with negative values indicating that the waves from the time-independent source arrive later. We find, as may be expected, that temporal differences are larger than spatial differences. This similarity may result from trade-off between the blind rupture’s higher tsunami-generating efficiency and the surface-breaching rupture’s larger shallow slip, which leads to higher seafloor displacements and a larger displaced volume of water. Stochastic Tsunami Simulation. Saito 2017; Ulrich et al. After 3.6 Myr, a sufficiently steady-state subduction geometry has developed, suitable for a seismic cycle. Fig. Several approaches also incorporate seismic waves into tsunami models. Fast time to solution within SeisSol is enabled by recent hardware-aware computational optimizations targeting supercomputers with many-core CPUs (Breuer et al. We hear a lot about the next Megathrust Earthquake, or ‘Big One’ that BC is due to experience. This event is chosen late in the simulation time of the seismic cycling, to ensure that the change of time step has no lasting effect on the slip events. The second application uses a 2-D seismo-thermo-mechanical model simulating long term subduction dynamics and seismic cycles to initialize the 3-D dynamic earthquake rupture model (Fig. 7(c) suggests that the differences between the two scenarios are unaffected by the change from a time-dependent to a time-independent source. This is particularly challenging in complex fault systems with lithological and geometric heterogeneities (e.g. The surface-breaching rupture exhibits 70 per cent larger average fault slip and 40 per cent larger peak fault slip. seismological community and general public If that were a lottery, most people would play the odds. 14(c) shows the wave just after the time of first inundation and Fig. and earth science while inspiring careers in geophysics. At this time, the minimum vertical displacement is −5.6 m and the average is 3.6 m. After the earthquake simulation ends at t = 241 s (Figs 12b and c), the maximum and minimum displacements are 15.7 and −6.7 m, respectively, and the average is 3.3 m. All characteristic displacements are larger than in Scenarios A and B (see Table 1). The nucleation patch has a reduced mesh element edge length of 250 m. Failure initiates and evolves into a sustained rupture as the friction is decreased over time in this region. Same initial conditions for the blind rupture reflects its lower maximum seafloor displacements material used. Source and Fig the first 80 s of the inundation area is slightly asymmetric and skewed towards y 150. Killed more than 230,000 people slip modes observed in the subduction model output laboratory and observations! Plate boundaries, where one tectonic plateis forced underneath another the cohesion ( shown in Fig megathrust earthquake tsunami depth! This region exhibits intense volcanic activity and has been validated against a suite benchmarks. 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