ダイレイタンシーを考慮したCIP法による砂層における断層関連撓曲の発生シミュレーション

抄録

An active fault that develops in a plain is often covered with a weak sand layer. The large-scale fault slip in a bedrock may spread to the surface and will frequently generate a fault rupture. Depending on the case, the fault slip occasionally appears on the surface as a fault flexure. This study identifies the reason for the formation of a fault flexure on the sand layer using numerical simulation. The simulation technique employs the constrained interpolation profile (CIP) method a new technique that overcomes the flaws such as numerical diffusion in the finite difference method. Furthermore, we study the influence of fault parameters on the configuration of the fault-related flexure. The experimental results indicate that the fault-related flexure is generated when a shear-zone migration occurs in the sand. We ascertain that the velocity of the shear-zone migration is proportional to the velocity of the fault slip. As a result, we conclude that this migration is probably one of causes of fault-related flexure generation at faulting. Therefore, we conclude that the velocity and acceleration of the fault slip affect the configuration of the fault-related flexure.