Evidence for tidal triggering of high‐amplitude rapid tremor reversals and tremor streaks in northern Cascadia
Evidence for tidal triggering of high‐amplitude rapid tremor reversals and tremor streaks in northern Cascadia
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卡斯卡迪亚北部潮汐触发高振幅快速地震逆转和地震条纹的证据
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
A. Ghosh
中科院分区：
文献类型：
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作者：
T. Thomas;J. Vidale;H. Houston;K. Creager;J. Sweet;A. Ghosh
我们通过分析由子阵列阵列数据的多波束反投影确定的高分辨率震颤位置和振幅，提供了构造震颤传播、震颤振幅和潮汐应力之间的新联系。对于两次卡斯卡迪亚阵发性震颤和滑动事件，我们观察到重复的高振幅快速震颤反转（RTR）和震颤条纹。它们往往发生在震动幅度最高的时候，并且几乎完全发生在断层上受逆冲、潮汐引起的剪切应力期间。我们推测，来自潮汐载荷力的推力促进剪切应力触发了 RTR 和条纹，从而有力地使慢滑锋后面的弱化断层再次破裂。 RTR 和条纹期间颤动的高速率和幅度与慢滑移区前缘的活动最活跃和最响亮的假设形成鲜明对比。这意味着慢地震滑动迁移的时空模式比之前报道的更加复杂。
We provide a new link between tectonic tremor propagation, tremor amplitude, and tidal stresses by analyzing high‐resolution tremor locations and amplitudes determined by multibeam backprojection of data from an array of subarrays. For two Cascadia episodic tremor and slip events, we observe repeating, high‐amplitude rapid tremor reversals (RTRs) and tremor streaks. They tend to occur when tremor amplitudes are highest and occur almost exclusively during periods of thrust‐encouraging, tidally induced shear stress on the fault. We speculate that thrust‐encouraging shear stress from tidal loading forces trigger RTRs and streaks that energetically rerupture the weakened fault behind the slow slip front. The high rate and amplitude of tremor during RTRs and streaks stands in contrast to the hypothesis that activity at the leading edge of the slow slip zone is the most energetic and loudest. This implies that the spatiotemportal pattern of slow earthquake slip migration is even more intricate than previously reported.