Frictional constraints on crustal faulting
Frictional constraints on crustal faulting
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DOI：
10.1029/96jb00405
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发表时间：
1996-06-10
影响因子：
3.9
通讯作者：
Cocco, M
中科院分区：
文献类型：
--
作者：
Boatwright, J;Cocco, M
我们考虑断层摩擦性质的变化如何影响地震断层现象。特别是，我们认为断层摩擦力的横向变化产生了在大地震中观察到的滑动的显著不均匀性。我们使用速率和状态相关的摩擦定律对这些变化进行建模，其中我们将速度弱化行为区分为tyro场：强地震场非常速度弱化，弱地震场轻微速度弱化。同样地，我们将速度强化行为区分为两个场：柔顺场是轻微的速度强化，粘性场是非常的速度强化。强地震场包括地震滑移集中或粗糙体。两个“中间”领域，弱地震和兼容，摩擦速度的依赖性，接近速度中性：这些领域调制的构造载荷和动态破裂过程。在地震间隔期间，弱地震区和顺从区抗震地滑动，而强地震区保持锁定，演变成仅在主震中失效的应力集中。弱地震区表现出大部分的震间活动和余震，但也可以蠕变地震。这种“混合”摩擦特性可以从临界滑移距离的充分不均匀分布中获得。该模型还提供了一种破裂停止机制：动态破裂锋面在渗透到未加载的抱怨或弱地震区时减速，产生广泛的加速后滑区域。两者都有余震发生。断层周围的弱震区和柔顺区，但大部分应力是通过非活动滑动扩散的。这些外围区域的快速后滑也可以通过重新加载在主震中滑动然后愈合的弱断层区域而在主震破裂区域内产生余震。我们通过比较1966年帕克菲尔德、1979年狼湖和1984年摩根山地震的地震活动性和同震滑动来测试这个摩擦模型。事件间的地震活动和余震似乎发生在断层地区以外的地区的重大滑动：这些地区被解释为弱地震或兼容，这取决于他们是否表现出事件间的地震活动。
We consider how variations in fault frictional properties affect the phenomenology of earthquake faulting. In particular, we propose that lateral variations in fault friction produce the marked heterogeneity of slip observed in large earthquakes. We model these variations using a rate- and state-dependent friction law, where we differentiate velocity-weakening behavior into tyro fields: the strong seismic field is very velocity weakening and the weak seismic held is slightly velocity weakening. Similarly, we differentiate velocity-strengthening behavior into two fields: the compliant field is slightly velocity strengthening and the viscous field is very velocity strengthening. The strong seismic field comprises the seismic slip concentrations, or asperities. The two ''intermediate'' fields, weak seismic and compliant, have frictional velocity dependences that are close to velocity neutral: these fields modulate both the tectonic loading and the dynamic rupture process. During the interseismic period, the weak seismic and compliant regions slip aseismically, while the strong seismic regions remain locked, evolving into stress concentrations that fail only in main shocks. The weak seismic areas exhibit most of the interseismic activity and aftershocks but can also creep seismically. This ''mixed'' frictional behavior can be obtained from a sufficiently heterogenous distribution of the critical slip distance. The model also provides a mechanism for rupture arrest: dynamic rupture fronts decelerate as they penetrate into unloaded complaint or weak seismic areas, producing broad areas of accelerated afterslip. Aftershocks occur on both. the weak seismic and compliant areas around a fault, but most of the stress is diffused through aseismic slip. Rapid afterslip on these peripheral areas can also produce aftershocks within the main shock rupture area by reloading weak fault areas that slipped in the main shock and then healed. We test this frictional model by comparing the seismicity and the coseismic slip for the 1966 Parkfield, 1979 Coyote Lake, and 1984 Morgan Hill earthquakes. The interevent seismicity and aftershocks appear to occur on fault areas outside the regions of significant slip: these regions are interpreted as either weak seismic or compliant, depending on whether or not they manifest interevent seismicity.