A study on interaction of asperilies based on laboratory and numerical experimets

本文基于二自由度块弹簧模型和大尺度双轴实验，研究了板边界上的各种滑移模式。滑动实验进行了使用大型花岗岩块与预先存在的断层面的长度为100厘米。通过插入一个薄的聚四氟乙烯片，在断层长度的一半上提供了速度加强摩擦，而另一半则保留了裸露岩石表面的速度减弱摩擦。在恒速加载条件下，动态粘滑在速度弱化区反复发生，在速度强化区产生后滑。速度加强区也经历了较小的同震滑移，其震级随着远离速度减弱区而减小。在实验室实验中观察到的行为进行了定量模拟的两个自由度块弹簧模型，其中两个块（块1和块2）连接的线性弹簧和驱动器驱动的缓慢移动。假设每个块体上的摩擦服从速率和状态相关摩擦定律。当假定a-b对于块1为负，而对于块2为正时，后滑发生在块2处。该模型还能再现板块边界上广泛的滑移模式，包括幕式慢滑移。

We studied various slip modes on a plate boundary on the basis of a two-degree-of-freedom block-spring model and large-scale biaxial experiments. Slip experiments were conducted using large granite blocks with a pre-existing fault surface of 100 cm in length. Velocity-strengthening friction was given over a half of the fault length by inserting a thin Teflon sheet, while the other half retained velocity-weakening friction of the bare rock surface. Under a loading at a constant velocity, dynamic stick-slip repeated on the velocity-weakening region, causing afterslip on the velocity-strengthening region. The velocity-strengthening region experienced small coseisic slip as well, with the magnitude decreasing with the distance from the velocity-weakening region. The behaviors observed in the laboratory experiments were quantitatively simulated by a two-degree-of-freedom block-spring model, in which two blocks (Block 1 and Block 2) are connected by a liner spring and driven by a slowly moving driver. The friction on each block was assumed to obey rate and state dependent friction law. When a-b was assumed to be negative for Block 1, and positive for Block 2, afterslip occurred at Block 2. This model can also reproduce wide spectrum of slip modes observed on a plate-boundary, including episodic slow slip.