[DM-P-06] A spontaneous dynamic fault rupture simulation without giving a priori rupture starting area and rupture stopping area
The dynamic fault rupture simulation was conducted for a virtual fault model with a width of 2km using the three-dimensional finite difference method without giving a priori rupture starting area and rupture stopping area by changing the coefficient of friction or changing the frictional constitutive law. The rupture was spontaneously triggered in the center of the model and stopped before reaching the edge of the model.
A rectangular parallelepiped model was prepared with 60km in the fault strike direction (x direction), 30km in the fault orthogonal direction (y direction), and 18km in the depth direction (z direction). This model had the fault with a width of 10km which was considered to be ruptured, and the surface layer 4km above it. The static rock pressure due to the solid materials that make up the crust and the fluid pressure due to the crustal fluid was considered. Similar to the conventional virtual fault model, the rigidity at the center of the model was set high and the rigidity at the edge of the model was set low in the strike direction of the fault. By moving the fault orthogonal end of the model in the direction in which the largest shear stress was generated on the fault plane, the shear stress that ruptured the fault plane was loaded.
Since the friction coefficient was set small in the surface layer, it ruptured in advance, and in the deep part, the effective restraining stress became small due to the large crustal fluid pressure, and rupture occurred in advance as well. Eventually, the central part of the fault ruptured dramatically, and it stopped after rupture propagation of about ±10km in the strike direction of the fault. The rupture started at the boundary of explorable rigidity.
A rectangular parallelepiped model was prepared with 60km in the fault strike direction (x direction), 30km in the fault orthogonal direction (y direction), and 18km in the depth direction (z direction). This model had the fault with a width of 10km which was considered to be ruptured, and the surface layer 4km above it. The static rock pressure due to the solid materials that make up the crust and the fluid pressure due to the crustal fluid was considered. Similar to the conventional virtual fault model, the rigidity at the center of the model was set high and the rigidity at the edge of the model was set low in the strike direction of the fault. By moving the fault orthogonal end of the model in the direction in which the largest shear stress was generated on the fault plane, the shear stress that ruptured the fault plane was loaded.
Since the friction coefficient was set small in the surface layer, it ruptured in advance, and in the deep part, the effective restraining stress became small due to the large crustal fluid pressure, and rupture occurred in advance as well. Eventually, the central part of the fault ruptured dramatically, and it stopped after rupture propagation of about ±10km in the strike direction of the fault. The rupture started at the boundary of explorable rigidity.
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