Interaction of slip on asperities: Numerical simulation of seismic cycles on a two-dimensional planar fault with nonuniform frictional property
Interaction of slip on asperities: Numerical simulation of seismic cycles on a two-dimensional planar fault with nonuniform frictional property
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DOI：
10.1029/2004jb003001
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发表时间：
2004-12-22
影响因子：
3.9
通讯作者：
Kato, N
中科院分区：
文献类型：
--
作者：
Kato, N
进行了数值模拟，以了解板块界面上摩擦滑动的变化和地震的复杂重演。考虑无限大均匀弹性介质中的平面正方形断层，假定断层上的摩擦应力服从与速率和状态有关的摩擦定律。在模型断层上引入了摩擦本构参数的不均匀性。在断裂面上，一个或两个具有速度弱化摩擦性质的圆形斑块被速度增强区包围。减速摩擦可能发生不稳定滑移，而增速摩擦可能发生抗震滑移。速度减弱的斑块对应于凹凸体，因为那里可能发生强烈的地震滑动。模拟结果表明，当减速块尺寸接近地震成核的临界尺寸时，就会发生幕式无震滑动事件(慢震)。震后滑动在速度增强区的传播是在速度弱化区的地震之后进行的。当震后滑动到达另一个减速带时，可能在该带上触发地震，从而产生双地震。两次地震之间的时间延迟随两个速度弱化区块之间的距离或两个速度弱化区块之间的速度增强程度的增加而增大。当两个减速块之间的距离较长时，一个块上的地震不会直接引起另一个块上的地震。在这些情况下，由于两个地块破裂的相互作用，可能会出现复杂的地震复发，地震和同震滑动的复发间隔在每个速度弱化地块上不是恒定的。
Numerical simulation is conducted to understand the variety of frictional sliding on a plate interface and complex recurrence of earthquakes. A planar square fault in an infinite uniform elastic medium is considered, and the frictional stress on the fault is assumed to obey a rate- and state-dependent friction law. Nonuniformity in a frictional constitutive parameter is introduced on the model fault. On the fault plane, one or two circular patches with velocity-weakening frictional property are surrounded by velocity-strengthening areas. Unstable slip may occur for velocity-weakening friction and aseismic sliding occurs for velocity-strengthening friction. Velocity-weakening patches correspond to asperities because intense seismic slip may occur there. Simulation results indicate that episodic aseismic slip events (slow earthquakes) occur when the velocity-weakening patch size is close to the critical size of earthquake nucleation. Propagation of postseismic sliding on the velocity-strengthening region follows an earthquake at a velocity-weakening patch. When the postseismic sliding reaches another velocity-weakening patch, an earthquake may be triggered at the patch, resulting in a double earthquake. The time delay between two events of the double earthquake increases with the distance between the two velocity-weakening patches or the degree of velocity strengthening in the region between the patches. When the distance between the two velocity-weakening patches is long, an earthquake at one patch does not directly cause an earthquake at the other patch. In these cases, complex earthquake recurrence may appear due to the interaction between ruptures at the two patches, and the recurrence interval of earthquakes and coseismic slip is not constant at each velocity-weakening patch.