8:45 AM - 9:00 AM
[S13-5-02] Dynamic Rupture Simulations Constrained by Experimental Data to Investigate the Fault Behavior of Mega-Thrust Earthquakes
The investigation of dynamic rupture propagation is very important to understand the seismic behavior of mega-thrust earthquakes such as the 2011 Tohoku earthquake. The shallow parts of the fault (near the trench) hosted large slip and long period seismic wave radiation, whereas the deep parts of the rupture (near the coast) hosted smaller slip and strong radiation of short period seismic waves. Understanding such depth-dependent feature of the rupture process of the Tohoku earthquake is necessary as it may occur during future mega-thrust earthquakes in this and other regions. In order to achieve such understanding, dynamic rupture modeling is an important tool (e.g., Galvez et al., 2014). By incorporating the results of laboratory studies of samples of fault materials collected from plate boundary fault zones, such as the Japan Trench, dynamic rupture simulations can be made more realistic.
In this study, we developed dynamic rupture models of the Tohoku earthquake based on initial conditions and fault strength properties constrained by results of experimental studies (Hirono et al., 2016). Our large-scale simulation used the 3D spectral element method on unstructured grids (Galvez et al., 2014) with performance tunning for the Earth Simulator at JAMSTEC.
Our model reproduced the depth-dependency of the rupture process of the Tohoku earthquake. We also examine the sensitivity of the results to model parameters and assumptions, for instance to the value of the slip weakening distance (Dc). We find that the value of Dc does not affect the final slip distribution, as long as it is small enough to allow the rupture to develop and propagate to the trench. A long Dc (order of 10 m) is reasonable in terms of fracture energy and promotes the generation of long period seismic waves on the shallow part of the fault.
In this study, we developed dynamic rupture models of the Tohoku earthquake based on initial conditions and fault strength properties constrained by results of experimental studies (Hirono et al., 2016). Our large-scale simulation used the 3D spectral element method on unstructured grids (Galvez et al., 2014) with performance tunning for the Earth Simulator at JAMSTEC.
Our model reproduced the depth-dependency of the rupture process of the Tohoku earthquake. We also examine the sensitivity of the results to model parameters and assumptions, for instance to the value of the slip weakening distance (Dc). We find that the value of Dc does not affect the final slip distribution, as long as it is small enough to allow the rupture to develop and propagate to the trench. A long Dc (order of 10 m) is reasonable in terms of fracture energy and promotes the generation of long period seismic waves on the shallow part of the fault.