Occurred at a subduction zone where one plate was thrust over another. Tsunami generation from landslides is simulated well by established software (e.g. LeVeque et al. Use appropriate media player to utilize captioning. 13). located in Washington, DC. 2004; Murphy et al. In the future, the here presented scenarios may be useful for comparison of alternative dynamic earthquake-tsunami modelling approaches or linking choices, and can be readily developed into more complex applications to study how earthquake source dynamics influence tsunami genesis, propagation and inundation. Tsunamis and splay fault dynamics. Characteristics for the blind (Scenario A), surface-breaching (Scenario B) and subduction-initialized (Scenario C) dynamic earthquake rupture models. Linked parameters of the subduction model fault are available at 649 locations and the slice through the earthquake model fault allows initializing 849 fault locations. In most of these zones a continental plate is overriding an oceanic plate because the oceanic plate is heavier and colder. This ensures that they experience the same stress field and host the same on-fault properties. (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. In comparison to the two scenarios in Section 3, the average dynamic stress drop and rupture velocity for this subduction-initialized earthquake are lower, but fault slip and seafloor uplift are larger. © The Author(s) 2020. Recent lower resolution scenarios require 4 hr on 5000 Sandy Bridge cores of the supercomputer SuperMucNG (Ulrich et al. In addition, the material properties, stress state and friction coefficients from the 2-D slip event are extended into the third dimension in the earthquake model. These methods are based on the one-way linkage of a 3-D dynamic earthquake rupture and seismic wave propagation model with a hydrostatic shallow water tsunami model. 2020). Direct comparison between the modelled tsunami results and the Tohoku tsunami observations is hampered by the complex interplay of bathymetry, sea surface height, and wave travel time, but we expect higher slip in the scenario than observed for this event to also be reflected in a larger tsunami in the scenario than observed. Data Services (DS), and This is particularly challenging in complex fault systems with lithological and geometric heterogeneities (e.g. 6, the (filtered) source displacements of the blind rupture in Scenario A produce a smooth wave while those in Scenario B produces more abrupt initial displacements of the water column, as discussed in Section 5.1. Here, we extend the approach that initializes a 2-D dynamic earthquake rupture with a subduction and seismic cycle model (van Zelst et al. This results in a Poisson solid with Lame’s parameter equal to the shear modulus (λ = G). The fault experiences a linearly increasing static strength with depth (Fig. Pore fluid pressure is elevated at a ratio of 0.95 to the lithostatic stress. The unstructured output from the earthquake model is bilinearly interpolated to a structured mesh at a resolution of 1000 m. As previously done, we apply a space-time Fourier filter to Δb which is discussed in Section 5.1. 2009). Constraints are particularly lacking in locations where observational data is sparse, either because earthquakes have not yet occurred or instrumentation is poor. We initialize the dynamic rupture model by porting the fault geometry and strength, material properties and stress state from one slip event in the subduction model. ADER is an explicit time-stepping method that achieves the same approximation order in space and time, but without requiring multiple stages for high discretization order, as in, for example Runge–Kutta schemes. The megathrust earthquake involved the Juan de Fuca Plate from mid-Vancouver Island, south along the Pacific Northwest coast as far as northern California. 2009; DeDontney & Rice 2011). We note that the seafloor displacements in both scenarios differ less than the slip, partially explaining this contrast. This behaviour is consistent with a simulation of the 2004 Indian Ocean tsunami (Poisson et al. Wendt et al. There is a 1 in 4 chance that we’ll experience a major earthquake in the next 50 years, and a 1 in 10 chance that it will be a megathrust (usually a magnitude 9+). 10c). The resulting earthquake model includes a curved fault geometry and heterogeneous material properties and stress field, and the frictional parameters along the fault vary with depth. 2005) in which shear traction decreases from its static to its dynamic value just behind the earthquake rupture front (see Appendix B). Direct studies of how subduction characteristics, earthquake initial conditions and earthquake dynamics govern tsunami behaviour can help understand hazard in a given subduction zone. Keywords: stochastic tsunami simulation, earthquake source modeling, uncertainty and sensitivity of tsunami hazard, sunda megathrust, West sumatra. Fault (pink) is 400 km along strike. In all three scenarios, use of a time-independent source results in more constant arrival times at the coast; the coast near the hypocentre is inundated later and the more distant coast is inundated earlier than for the tsunami with the time-dependent source. There is also variability in the static and dynamic friction coefficients with depth. The earthquake and tsunami computational models utilized here are open-source, use discontinuous Galerkin schemes, and are facilitated by highly optimized parallel algorithms and software. 2018; Ramos & Huang 2019). The eastern Aleutian arc extends from the Alaska Peninsula in the east to the Fox Islands in the west. After the onset of failure, the earthquake model fault weakens according to a linear slip-weakening friction law (Andrews 1976) and |$\mu _{s}^{\prime }$| changes with slip to an effective dynamic value, |$\mu _{d}^{\prime }$|. To initialize the earthquake model using the subduction model, we port information from a single slip event following methods similar to those for initializing a 2-D earthquake model by van Zelst et al. 4 shows Δb at t = 102 s. Snapshots of the simulated tsunami wave-field are shown in Fig. 16(a) shows the history of inundation. In addition, the modelled maximum vertical seafloor displacement is 28.1 m and not at the trench, while maximum values from the Tohoku earthquake are estimated to be ∼10 m at the trench (Fujiwara et al. Salaree & Okal 2020). 3) at points along a cross section at y = 0 through the 3-D earthquake model fault in Scenario C. Green stars are locations initially at failure, before adjustments are made to prevent such failure in the sediments and at outliers (see Section 4.1.1). 2018; Ulrich et al. b(x,y) = \left\lbrace \begin{array}{@{}l@{\quad }l@{}}0.05\, (x-x_0) & \text{for } x \gt x_0 \\
SeisSol is the computational model used to simulate 3-D dynamic earthquake rupture and seismic wave propagation (see Appendix A1). This is not the case for Scenarios A or B, however, where the width of the inundation corridor remains relatively unchanged. 2009, 2018). Fully coupled simulations of megathrust earthquakes and tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone, Fully coupled simulations of megathrust earthquakes and tsunamis in the Japan Trench, Nankai Trough, and Cascadia subduction zone, Dynamic rupture simulations of the m6.4 and m7.1 July 2019 Ridgecrest, California, earthquakes, A self-consistent mechanism for slow dynamic deformation and large tsunami generation for earthquakes in the shallow subduction zone, Dynamic wedge failure and along-arc variations of tsunami genesis in the Japan trench margin, FDM Simulation of seismic waves, ocean acoustic waves, and tsunamis based on tsunami-coupled equations of motion, Significant tsunami observed at ocean-bottom pressure gauges during the 2011 off the Pacific coast of Tohoku Earthquake, Seismic- and Tsunami-wave propagation of the 2011 off the Pacific Coast of Tohoku earthquake as inferred from the Tsunami-coupled finite-difference simulation, Successive estimation of a tsunami wavefield without earthquake source data: a data assimilation approach toward real-time tsunami forecasting, SRCMOD: an online database of finite-fault rupture models, The earthquake-source inversion validation (SIV) project, Clawpack: building an open source ecosystem for solving hyperbolic PDES, Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra, Parallel, memory efficient adaptive mesh refinement on structured triangular meshes with billions of grid cells, Differences between heterogenous and homogenous slip in regional tsunami hazards modelling, Tsunami Forerunner of the 2011 Tohoku Earthquake Observed in the Sea of Japan, Shallow slip amplification and enhanced tsunami hazard unravelled by dynamic simulations of mega-thrust earthquakes, Tsunamigenic earthquake simulations using experimentally derived friction laws, Frictional constitutive law at intermediate slip rates accounting for flash heating and thermally activated slip process, Cluster design in the earth sciences: Tethys, International Conference on High Performance Computing and Communications, The three-dimensional dynamics of dipping faults, Surface deformation due to shear and tensile faults in a half-space, Mode-wave equivalence and other asymptotic problems in tsunami theory, Three-dimensional dynamic rupture simulation with a high-order discontinuous Galerkin method on unstructured tetrahedral meshes, Verification of an ADER-DG method for complex dynamic rupture problems. Use appropriate media player to utilize captioning. |\tau _{s}| = c - \mu _{s}\tau _{n}^{\prime },
Methodological approach, A Bayesian source model for the 2004 great Sumatra-Andaman earthquake, Sustained petascale performance of seismic simulations with SeisSol on SuperMUC, Supercomputing. The plates are locked and the overlying plate is forced back. 2008). Since 1900, all earthquakesof magnitude 9.0 or greater have been megathrust earthquakes. Japan earthquake and tsunami, severe natural disaster that occurred in northeastern Japan on March 11, 2011, and killed at least 20,000 people. Comparison of sea surface height (ssh) over time at points on the coast near (c) x = 540 km and y = 0 km and (d) x = 540 km and y = 150 km. When a megathrust earthquake strikes, the land can drop by five feet or more. It solves the seismic wave equation in velocity-stress formulation using a Discontinuous Galerkin (DG) scheme with Arbitrary high-order DERivative (ADER) time stepping: ADER-DG (Dumbser & Käser 2006; Käser & Dumbser 2006). \Delta b= \Delta z - \Delta x \frac{\partial b}{\partial x} - \Delta y \frac{\partial b}{\partial y} ,
Key earthquake characteristics for the blind (Scenario A) and surface-breaching (Scenario B) ruptures are compared in Table 1. IRIS staff and subawardees oversee the construction, 2007). When initializing the earthquake model from a subduction model, we must honor the plane-strain conditions of the 2-D subduction model while mapping the stress field into the 3-D earthquake model. This is the value of |$\mu _{s}^{\prime }$| above 40 km depth. For the transfer between models, the unstructured output from the earthquake model is bilinearly interpolated to an intermediate uniform Cartesian mesh. Also, key characteristics of the tsunami sourced by the blind rupture (Scenario A) and the surface-breaching rupture (Scenario B) are summarized in Table 2. 2011; Gabriel et al. The shallow sediments are always at plastic failure, but velocity strengthening allows continuous creep through time without nucleation of brittle failure. At t = 1200 s, just before first inundation in both scenarios, the heights of the peaks nearest the beach are more similar (Fig. The subducting oceanic plate consists of 4 km thick sediments, a 2 km thick basaltic upper crust, a 5 km thick gabbroic lower oceanic crust, and a lithospheric mantle (Fig. $$\begin{eqnarray}
In order to restrict nucleation laterally, we then set |$\mu _{s}^{\prime } = 0.025$| in the regions outside of, but at the same depths as, the nucleation zone. Fast time to solution within SeisSol is enabled by recent hardware-aware computational optimizations targeting supercomputers with many-core CPUs (Breuer et al. (d) Log of the second invariant of the deviatoric stress tensor, |$\sigma ^{\prime }_{\rm II}$|, which controls yielding in the subduction model (see eq. The differences occur inland from the coast, where Scenario B inundates a wider corridor. Motion along this section of the arc is characterized by arc-perpendicular convergence and Pacific plate subduction beneath thick continental lithosphere. \end{eqnarray}$$. Fig. 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. Our computations of tsunami propagation and inundation yield model ﬂow depths and inundations consistent with sparse historical A 'megathrust' earthquake caused by a rupture along New Zealand's largest fault line is a question of 'when', not 'if' according to experts (pictured: graphic illustrating projected tsunami) 2 / 4 Coupled feedback mechanisms beyond one-way linking from earthquake to tsunami also may be analysed in future work. 2014). IRIS is a consortium of over 120 US universities dedicated 2015, 2019). Violet areas outline aftershocks following 20th century megathrust earthquakes. Play now. Second, we want to recognize the following researchers that have contributed directly to this project over its years in development: N. Beisiegel, A. Breuer, L. Dalguer, A. Fichtner, P. Galvez, H. Igel, A. Jeschke, M. Käser, O. Meister, C. Pelties, K. Rahnema, S. Rettenberger and S. Wollherr. 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