Since the 1999 Chi-chi earthquake and the 1999 Kocaeli earthquake damaged many important structures due to surface rupture, as well as a strong motion by the fault rupture, displacement and inclination in ground surface become the significant issues. In this study, we conducted fault rupture simulation using two and three dimensional finite element method for the 2014 Kamishiro Fault Nagano prefecture earthquake, which is a thrust fault type earthquake with an observed surface rupture of 9 km in length, and confirmed the applicability of numerical method and conditions, such as initial stress distribution, modeling of the fault plane and constitutive law, by comparing results with the observed ground motions and displacement. As a result, the acceleration response could not be simulated due to mesh size and constitutive law of fault plane. The displacement of 2D-FEM becomes larger than the actual displacement while the 3D-FEM yields results, which are in good agreement with the actual displacement.
Since the 1999 Chi-chi earthquake and the 1999 Kocaeli earthquake damaged many important structures due to surface rupture, as well as a strong motion by the fault rupture, displacement and inclination in ground surface become the significant issues. Generally strong motions are estimated by Green's function method and fault displacement is estimated based on geological surveys. However an earthquake occurs by rupture of earthquake source fault. When the displacement is large, it will come up to the ground surface as a surface rupture. Therefore, ideal analytical model is able to simulate a fault rupture process and estimate displacement and strong motion at the same time. Fault rupture simulations by Finite Difference Method (FDM), Finite Element Method (FEM) and Boundary Element Method (BEM) are carried out. However, they have not become practical as analytical results greatly vary according to initial stress conditions and modeling of fault rupture.
In this study, we conducted fault rupture simulation using two and three dimensional finite element method (2D-FEM, 3D-FEM) for the 2014 Kamishiro Fault Nagano prefecture earthquake (Mw 6.3), which is a thrust fault type earthquake with an observed surface rupture of 9 km in length. The analytical method and modeling of fault is dynamic response analysis considering fault rupture process proposed by Toki & Miura (1985) and Toki & Sawada (1988). We confirmed the applicability of numerical method and conditions, such as initial stress distribution, modeling of the fault plane and constitutive law, by comparison with the observed surface ground motions and displacement.
