Effect of Branching Angles on Dynamic Rupture Processes of 3-D Branching Fault Systems

Abstract:

Fault branching is one of the geometric complexities of fault systems that exists widely in nature, and it may seriously affect the rupture propagation pattern of fault systems. This study used the boundary integral equation method (BIEM) to simulate the rupture process of 3-D two-fork branching fault systems with a friction law dependent on the normal stress. The rupture inclination near the intersection was analyzed theoretically with Mohr’s circle, and special attention was paid to study how ruptures on the upper and lower branch planes affect the stress and rupture on each other separately. The results showed that the two branch planes influence each other in different ways, and the intensity of this influence varies with the branching angle. The rupture of the lower branch plane produces a strong negative effect on the rupture of the upper branch plane when the branching angle is small, but almost no negative effect in case of a large branching angle. The rupture of the upper branch plane suppresses the rupture of the lower one whether the branching angle is large or small.