Fortnightly modulation of San Andreas tremor and low-frequency earthquakes
Fortnightly modulation of San Andreas tremor and low-frequency earthquakes
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DOI：
10.1073/pnas.1524316113
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发表时间：
2016-08-02
影响因子：
11.1
通讯作者：
Johnson, Paul A.
中科院分区：
文献类型：
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作者：
van der Elst, Nicholas J.;Delorey, Andrew A.;Johnson, Paul A.
固体潮对脆性-韧性（地震-地震）转换附近断层上的震颤和低频地震（LFEs）进行调制。对潮汐应力的响应携带了断层强度和流变学的信息。在这里，我们分析的LFE响应每两周的潮汐，它调制的幅度超过14天的周期的每日潮汐应力。LFE率是最高的，在打蜡每两周的潮汐，与LFE最强烈的促进时，每天的应力超过以前的峰值应力的最大幅度。这种模式意味着一个阈值故障过程中，与滑动开始时，应力超过当地故障强度。每两周调制的敏感性的变化可能反映了应力集中的程度上LFE生产的脆性凹凸嵌入在一个其他aseparctic故障。
Earth tides modulate tremor and low-frequency earthquakes (LFEs) on faults in the vicinity of the brittle-ductile (seismic-aseismic) transition. The response to the tidal stress carries otherwise inaccessible information about fault strength and rheology. Here, we analyze the LFE response to the fortnightly tide, which modulates the amplitude of the daily tidal stress over a 14-d cycle. LFE rate is highest during the waxing fortnightly tide, with LFEs most strongly promoted when the daily stress exceeds the previous peak stress by the widest margin. This pattern implies a threshold failure process, with slip initiated when stress exceeds the local fault strength. Variations in sensitivity to the fortnightly modulation may reflect the degree of stress concentration on LFE-producing brittle asperities embedded within an otherwise aseismic fault.