Characteristics of secondary slip fronts associated with slow earthquakes in Cascadia
Characteristics of secondary slip fronts associated with slow earthquakes in Cascadia
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DOI：
10.1016/j.epsl.2017.01.046
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发表时间：
2017-04-01
影响因子：
5.3
通讯作者：
Krogstad, Randy D.
中科院分区：
文献类型：
--
作者：
Bletery, Quentin;Thomas, Amanda M.;Krogstad, Randy D.
我们实现了一个算法，自动检测迁移的低频地震在30分钟和32小时之间的时间尺度在2003年，2004年和2005年在卡斯卡迪亚慢滑事件。我们解释这些迁移的地震活动性作为一个被动的表现，传播速度比主前的次级滑动锋（SSFs）。我们确定了383 SSF的主要特征，包括时间，位置，持续时间，面积，传播速度和估计：他们的时刻，应力降，滑动，滑动速率。我们将相同的算法应用于2009年至2015年卡斯卡迪亚的连续震颤检测，并在4小时至32小时的时间尺度上表征了693个SSF。我们确定-据我们所知的第一次-许多11- 22.5小时长的SSFs之间的速度传播慢滑事件和以前报道的SSFs。SSF的系统检测填补了地震学和大地测量学可检测的慢地震过程之间的空白。SSF基本特征的分析表明，应力下降和滑动速率（中位数为5.8kPa和1.1mm/h）范围很广，以及SSF方向和持续时间之间的有趣关系，在其他情况下观察到，并可能有助于区分不同的物理模型，提出解释缓慢滑动现象。(C)2017年爱思唯尔B。V.保留所有权利。
We implement an algorithm to automatically detect migrations of low frequency earthquakes at time scales between 30min and 32h during the 2003, 2004 and 2005 slow slip events in Cascadia. We interpret these migrations of seismicity as a passive manifestation of secondary slip fronts (SSFs) that propagate faster than the main front. We identify the dominant features of 383 SSFs, including time, location, duration, area, propagation velocity and estimate: their moment, stress drop, slip, and slip rate. We apply the same algorithm to continuous tremor detection in Cascadia between 2009 and 2015 and characterize 693 SSFs at time scales between 4h and 32h. We identify -to our knowledge for the first time - numerous 11-22.5h long SSFs that propagate at velocities intermediate between slow slip events and previously reported SSFs. The systematic detection of SSFs fills a gap between seismically and geodetically detectable slow earthquake processes. Analysisof SSF basic features indicates a wide range of stress drops and slip rates (with medians of 5.8kPa and 1.1mm/h) as well as an intriguing relationship between SSF direction and duration that was observed in other contexts and could potentially help discriminate between the different physical models proposed to explain slow slip phenomena. (C) 2017 Elsevier B. V. All rights reserved.