Seismicity, Fault Architecture, and Slip Mode of the Westernmost Gofar Transform Fault
Seismicity, Fault Architecture, and Slip Mode of the Westernmost Gofar Transform Fault
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DOI：
10.1029/2022jb024918
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
J. Gong;W. Fan
中科院分区：
文献类型：
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作者：
J. Gong;W. Fan
海洋转换断层通过地震和地震滑动来调节板块运动。然而，这些断层的变形分配和滑移模式相互作用仍然难以捉摸，主要受到罕见观测的限制。我们利用 2008 年收集的 1 年海底地震仪数据来检测和定位最西端戈法尔转换断层的地震。 Gofar 的超快滑动速率导致观测期间发生约 30,000 次地震，为以前所未有的分辨率研究滑动模式、地震活动和断层结构之间的相互关系提供了绝佳的机会。地震分布表明，约100公里长的戈法尔转换断层明显分为五个区域，其中一个区域描绘了实验捕获的M6地震。此外，M6 级地震以东的一个屏障区在 M6 级地震之前发生了丰富的前震，并在之后停止了活跃的地震活动。障壁区深部有两层地震，它们对6级地震的反应不同。此外，与东太平洋海隆相连的区域也出现了准周期性地震群。地震活动分割表明，Gofar 断层在相邻断层斑块中存在多种滑移模式。地震的时空特征表明，复杂的断层结构和流体-岩石相互作用在调节戈法尔的滑移模式中发挥着主要作用，可能涉及多个并发的物理过程。
Oceanic transform faults accommodate plate motions through both seismic and aseismic slips. However, deformation partition and slip mode interaction at these faults remain elusive mainly limited by rare observations. We use 1‐year ocean bottom seismometer data collected in 2008 to detect and locate earthquakes at the westernmost Gofar transform fault. The ultra‐fast slipping rate of Gofar results in ∼30,000 earthquakes during the observational period, providing an excellent opportunity to investigate interrelations between the slip mode, seismicity, and fault architecture at an unprecedented resolution. Earthquake distribution indicates that the ∼100‐km‐long Gofar transform fault is distinctly segmented into five zones, including one zone contouring a M6 earthquake that was captured by the experiment. Further, a barrier zone east of the M6 earthquake hosted abundant foreshocks preceding the M6 event and halted its active seismicity afterward. The barrier zone has two layers of earthquakes at depth, and they responded to the M6 earthquake differently. Additionally, a zone connecting to the East Pacific Rise had quasi‐periodic earthquake swarms. The seismicity segmentation suggests that the Gofar fault has multiple slip modes occurring in adjacent fault patches. Spatiotemporal characteristics of the earthquakes suggest that complex fault architecture and fluid–rock interaction play primary roles in modulating the slip modes at Gofar, possibly involving multiple concurrent physical processes.