Rapid Tremor Migration During Few Minute-Long Slow Earthquakes in Cascadia
Rapid Tremor Migration During Few Minute-Long Slow Earthquakes in Cascadia
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DOI：
10.1029/2022jb025034
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发表时间：
2023-02-01
影响因子：
3.9
通讯作者：
Hawthorne, J. C.
中科院分区：
文献类型：
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作者：
Gombert, B.;Hawthorne, J. C.
现在，人们普遍发现慢地震表现出广泛的持续时间、力矩、滑动和传播速度。但并非所有类型的慢地震都经过了详细研究。在这里，我们探测持续时间在 1 到 30 分钟之间的地震爆发，这可能是由几分钟长的地震滑移爆发引起的。我们使用基于相干性的技术来检测卡斯卡迪亚温哥华岛下方的数千次地震爆发。然后，我们通过跟踪 8 公里区域内不断变化的震动位置来检查其中 17 个破裂。我们发现震颤以 3-25 m/s 的速度传播：比较长的震颤爆发更快。尽管一些观测偏差仍然存在，但短事件的速度似乎填补了观测到的慢地震谱中的空白。他们可能提供进一步的证据，表明无论断层带过程如何产生慢地震，它都必须允许较小破裂中更快的滑动和传播。
Slow earthquakes are now commonly found to display a wide range of durations, moments, and slip and propagation speeds. But not all types of slow earthquakes have been examined in detail. Here we probe tremor bursts with durations between 1 and 30 min, which are likely driven by few minute-long bursts of aseismic slip. We use a coherence-based technique to detect thousands of tremor bursts beneath Vancouver Island in Cascadia. Then we examine 17 of the ruptures by tracking their evolving tremor locations over an 8-km region. We find that tremor migrates at rates of 3-25 m/s: faster than longer tremor bursts. Though some observational biases persist, the short events' speeds appear to fill a gap in the spectrum of observed slow earthquakes. They may provide further evidence that whatever fault zone process creates slow earthquakes, it must allow for faster slip and propagation in smaller ruptures.