Interactions and triggering in a 3-D rate-and-state asperity model
Interactions and triggering in a 3-D rate-and-state asperity model
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DOI：
10.1002/jgrb.50187
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发表时间：
2013-05-01
影响因子：
3.9
通讯作者：
Favreau, P.
中科院分区：
文献类型：
--
作者：
Dublanchet, P.;Bernard, P.;Favreau, P.
我们提出了一个由周围地震蠕变驱动并由共面多重峰观测激发的多个地震粗糙体的 3-D 连续准动态速率和状态模型。我们的模型可以研究一组粗糙体之间相互作用的物理原理。首先，我们表明，以大森定律和事件间隔时间分布为特征的相互作用和聚类的数量取决于系统距粗糙体临界密度的距离，这与分隔源的屏障的摩擦特性有关。该阈值控制粗糙体群体破坏它们之间的蠕动屏障的能力，因此确定是否可能发生在同一事件中包含多个粗糙体的动态序列，这与观察到的幅度频率分布的预期一致。因此，粗糙体临界密度的概念提供了地震活动统计特性的力学解释。作为说明，我们使用了 2004 年 M-w 6 地震之前帕克菲尔德具体情况的数值结果，以推断表征圣安德烈亚斯断层这部分蠕变的稳态摩擦参数 (a-b)。我们估计 (a-b) 的值局部超过 0.001，该值处于已为 2004 年帕克菲尔德 6 级地震震后阶段提出的上限范围内。
We present a 3-D continuous quasi-dynamic rate-and-state model of multiple seismic asperities forced by surrounding aseismic creep and motivated by observations of coplanar multiplets. Our model allows to study the physics of interactions among a set of asperities. First, we show that the amount of interactions and clustering, characterized by the Omori law and interevent time distribution, depends on how far the system is from a critical density of asperities, which is related to the friction properties of the barriers separating the sources. This threshold controls the ability of a population of asperities to destabilize the creeping barriers between them and therefore determines whether dynamic sequences including several asperities in the same event might occur, in agreement with what is expected from observed magnitude-frequency distributions. Therefore, the concept of critical density of asperity provides a mechanical interpretation of statistical properties of seismicity. As an illustration, we used our numerical results in the specific case of Parkfield in the period preceding the M-w 6, 2004 earthquake, in order to infer the steady state friction parameter (a-b) characterizing the creep of this part of the San Andreas Fault. We estimate a value of (a-b) that locally exceeds 0.001, which is in the upper range of what has already been proposed for the postseimic period of the M-w 6, 2004 Parkfield earthquake.