The dynamic fault rupture simulation was conducted 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. It was conducted on condition that the shear rigidity was changed along the fault plane and that the shear stress on the fault plane was loaded by forced displacement. In this study, induced shear stress in the fault layer by the forced displacement was larger at the center part because of higher shear wave velocity and stress was smaller at the outskirts part because of lower shear wave velocity. The ununiform shear stress distribution caused spontaneous fault rupture starting from the central part in spite of constant frictional condition in this layer. The fault rupture was spontaneously stopped after the rupture spread up to around 10km in the x-direction without giving a priori rupture stopping area by frictional condition. It was consistent with previous studies in the fault rupture process that the rupture velocity was 3~3.5km/s at most. It was not incompatible that the stress drop was about 2MPa. We could estimate the near fault ground motion for our model fault by using this dynamic rupture simulation. The slip velocity time function directly calculated by the dynamic fault rupture simulation was consistent with previous study.

1 Introduction

In recent years, the dynamic fault rupture simulation is used widely for the solution of the physical phenomenon of the fault dislocation and so on.

Tsuda (2016) tried to reproduce the rupture process of mega-thrust earthquakes such as the 2011 off the Pacific coast of Tohoku Earthquake. Kase (2016) tried to explain the source process of the intersegmental rupture propagation for the 2014 northern Nagano earthquake. Kase et al. (2002) simulated the earthquake rupture process on the Uemachi fault system. Irie (2014) explored to be clear for the source properties of large inland strike-slip faults for strong motion prediction based on dynamic rupture simulation. However, in these simulations, the initial rupture area that was given smaller static friction coefficient and the rupture stop area in which rupture was not permitted were indispensable.

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