[S08P-18] Numerical experiments using a friction law both for rapid and slow sliding with radiation damping effect
To realize various fault slip behavior as regular and slow earthquakes, we assume a simple friction law. In the friction law, the frictional strength decreases due to fault slip and recovers with time. These two processes along the fault, slip-weakening and healing are the intrinsic ones to model regular and slow earthquake sequences. Here, an evolution equation of the frictional strength proposed by Nielsen et al. (2000) is used. In this equation, there are two frictional parameters, dc and tc, which represent a characteristic displacement for slip-weakening and a characteristic time for healing, respectively. The balance of these two parameters controls how frictional strength evolves depending on the fault slip history. To examine fault slip behavior with the evolution equation, a single degree of freedom elastic system, composed of a block and a spring with constant loading is introduced. The block starts to slip following the strength evolution equation when the shear stress acting on the contact surface of the block reaches the strength. On the other hand, the block is in stationary contact if the shear stress is less than the strength. Note that this is a classical constitutive law without direct effect in a rate- and state-dependent friction law (Nakatani, 2001). To examine the slip behavior depending on the above system, we modified a simulation code used in Aochi and Matsu’ura (2002), which introduces more complex evolution equation of fault strength. Some preliminary results show that both intermittent rapid and slow sliding with can be demonstrated depending on the two frictional parameters. These slip behaviors are similar with regular and slow earthquakes. In this presentation, we specifically investigate how radiation damping effect affects the slow sliding behavior.