The break of earthquake asperities imaged by distributed acoustic sensing
The break of earthquake asperities imaged by distributed acoustic sensing
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DOI：
10.1038/s41586-023-06227-w
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发表时间：
2023-08-02
期刊：
影响因子：
64.8
通讯作者：
Zhan, Zhongwen
中科院分区：
文献类型：
--
作者：
Li, Jiaxuan;Kim, Taeho;Zhan, Zhongwen
全球地震台阵的破裂成像揭示了与频率相关的破裂特征(1-4)，但高频辐射体的作用尚不清楚(3-5)。对更丰富的地壳地震的类似观测可以提供关键的约束，但如果没有超高密度的局部台阵，这种情况就很少见(6，7)。在这里，我们使用分布式声传感技术(8，9)对高频地震破裂辐射体进行成像。通过将100公里长的暗光纤电缆转换为10,000个通道的地震阵列，我们可以想象2021年加州羚羊谷6.0级地震的四个高频子事件。在将我们的结果与长周期矩释放(10，11)和动态破裂模拟进行比较后，我们认为所成像子事件是由于断层凹凸体的破裂-断层上更强的点或销-基本上调节了整体破裂行为。层叠序列中断层凹凸体的破裂可以促进其它衰减的破裂传播。这项研究强调了我们如何使用广泛的预先存在的光纤网络(12)作为高频地震天线来系统地研究区域中等规模地震的破裂过程。结合动态破裂模拟，可以提高我们对地震破裂动力学的理解。
Rupture imaging of megathrust earthquakes with global seismic arrays revealed frequency-dependent rupture signatures(1-4), but the role of high-frequency radiators remains unclear(3-5). Similar observations of the more abundant crustal earthquakes could provide critical constraints but are rare without ultradense local arrays(6,7). Here we use distributed acoustic sensing technology(8,9) to image the high-frequency earthquake rupture radiators. By converting a 100-kilometre dark-fibre cable into a 10,000-channel seismic array, we image four high-frequency subevents for the 2021 Antelope Valley, California, moment-magnitude 6.0 earthquake. After comparing our results with long-period moment-release(10,11) and dynamic rupture simulations, we suggest that the imaged subevents are due to the breaking of fault asperities-stronger spots or pins on the fault-that substantially modulate the overall rupture behaviour. An otherwise fading rupture propagation could be promoted by the breaking of fault asperities in a cascading sequence. This study highlights how we can use the extensive pre-existing fibre networks(12) as high-frequency seismic antennas to systematically investigate the rupture process of regional moderate-sized earthquakes. Coupled with dynamic rupture modelling, it could improve our understanding of earthquake rupture dynamics.