Slow Slip Event On the Southern San Andreas Fault Triggered by the 2017 Mw8.2 Chiapas (Mexico) Earthquake
Slow Slip Event On the Southern San Andreas Fault Triggered by the 2017 Mw8.2 Chiapas (Mexico) Earthquake
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DOI：
10.1029/2018jb016765
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发表时间：
2019-09
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通讯作者：
E. Tymofyeyeva;Y. Fialko;Junle Jiang;Xiaohua Xu;D. Sandwell;R. Bilham;T. Rockwell;Chelsea M. Blanton;Faith Burkett;A. Gontz;S. Moafipoor
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作者：
E. Tymofyeyeva;Y. Fialko;Junle Jiang;Xiaohua Xu;D. Sandwell;R. Bilham;T. Rockwell;Chelsea M. Blanton;Faith Burkett;A. Gontz;S. Moafipoor
对浅层断层蠕变的观察揭示了越来越复杂的与时间相关的滑动历史，包括准稳态蠕变和触发以及自发加速滑动事件。在这里，我们报告了圣安德烈亚斯断层南部最近发生的一次慢滑动事件，该事件是由发生在 3,000 公里外的 2017 年 Mw8.2 恰帕斯（墨西哥）地震引发的。大地测量和地质观测表明，麦加山和孟买海滩之间的圣安德烈亚斯断层南部一段 40 公里长的地表滑移发生在恰帕斯地震后几分钟，持续了一年多。蠕变的幅度和深度均沿走向变化。我们通过结合 Sentinel-1 干涉合成孔径雷达从不同视线获取的数据，得出了高分辨率的表面位移图。干涉合成孔径雷达得出的位移与蠕变计数据和表面偏移的现场测绘非常吻合。使用位错模型对表面位移数据进行反演表明，表面滑移的最高振幅与浅层（<1 km）瞬态滑移有关。我们对遵循速率和状态摩擦的走滑断层上的浅层蠕变进行了二维模拟，以约束可以产生观察到的行为的上地壳顶部几公里的摩擦特性。
Observations of shallow fault creep reveal increasingly complex time‐dependent slip histories that include quasi‐steady creep and triggered as well as spontaneous accelerated slip events. Here we report a recent slow slip event on the southern San Andreas fault triggered by the 2017 Mw8.2 Chiapas (Mexico) earthquake that occurred 3,000 km away. Geodetic and geologic observations indicate that surface slip on the order of 10 mm occurred on a 40‐km‐long section of the southern San Andreas fault between the Mecca Hills and Bombay Beach, starting minutes after the Chiapas earthquake and continuing for more than a year. Both the magnitude and the depth extent of creep vary along strike. We derive a high‐resolution map of surface displacements by combining Sentinel‐1 Interferometric Synthetic Aperture Radar acquisitions from different lines of sight. Interferometric Synthetic Aperture Radar‐derived displacements are in good agreement with the creepmeter data and field mapping of surface offsets. Inversions of surface displacement data using dislocation models indicate that the highest amplitudes of surface slip are associated with shallow (<1 km) transient slip. We performed 2‐D simulations of shallow creep on a strike‐slip fault obeying rate‐and‐state friction to constrain frictional properties of the top few kilometers of the upper crust that can produce the observed behavior.