Quasi-static slow-slip cycle simulation based on finite element modeling
Abstract
Earthquake cycle simulation (ESC) methods are used to understand the earthquake generation process at the plate boundary (e.g. Hori and Miyazaki 2011). Such techniques are also used for reproducing repeated slow slips (e.g. Matsuzawa et al. 2013). Many previous studies on ESCs use a combination of the rate- and state-dependent friction law at the fault plane and the boundary integral equation method (BIEM) based on homogeneous elastic half-space. This approach generally has a limitation in investigating the effect by introducing elastic and viscoelastic heterogeneity. In this study, we develop an ESC method combining crustal deformation calculation based on finite element (FE) method and the rate- and state-dependent friction law to consider these effects by incorporating heterogeneous structures and constitutive properties. To perform a simulation within a realistic time, we introduce a fast and scalable FE solver (Ichimura et al. 2016) that runs in a large scale parallel computing environment and an FE mesh generation method that is efficient for ESCs. Here we consider slow slip cycles that require smaller calculation cost than earthquake cycles.
We solve governing equations consisting of the equilibrium equation, the rate- and state- dependent friction law, and the time evolution law of the state variable. In solving this equation, stress change in the fault plane due to fault slips is calculated not by superimposing the slip response function as in the conventional method but based on the FE calculation. We introduce a version of the rate- and state-dependent friction law with a cut-off speed for slow slip calculation (Okubo 1989). We conducted long-term slow slip cycle simulation in the Bungo Channel using the proposed method based on heterogeneous elasticity structure and a modified version of the friction parameters used in Matsuzawa et al. (2013). Although the detailed comparison is still under consideration, the results are consistent with the results based on the BIEM. We will investigate the effects of elastic and viscoelastic heterogeneity on slow slip occurrence patterns. Acknowledgment: We used the fault parameter provided by Dr. Matsuzawa Takanori. The results were obtained using the K computer at the RIKEN (Proposal number hp170249, hp180207).- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T33F0468A
- Keywords:
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- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITYDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICSDE: 8163 Rheology and friction of fault zones;
- TECTONOPHYSICS