Along-Arc Heterogeneity in Local Seismicity across the Lesser Antilles Subduction Zone from a Dense Ocean-Bottom Seismometer Network
Along-Arc Heterogeneity in Local Seismicity across the Lesser Antilles Subduction Zone from a Dense Ocean-Bottom Seismometer Network
复制标题
从密集海底地震计网络看小安的列斯群岛俯冲带局部地震活动的沿弧不均匀性
DOI：
10.1785/0220190147
复制
发表时间：
2020-01-01
影响因子：
3.3
通讯作者：
Wilson, Marjorie
中科院分区：
文献类型：
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作者：
Bie, Lidong;Rietbrock, Andreas;Wilson, Marjorie
小安的列斯群岛弧是消耗缓慢扩张的大西洋岩石圈的两个俯冲带之一。缓慢扩张可能导致大西洋岩石圈比快速扩张的太平洋岩石圈更普遍且非均质地水化，从而影响流体进入深部地幔的通量。了解地震活动的分布有助于揭示流体对地球动力学和发震过程的影响。然而，缺乏整个小安的列斯俯冲带局部地震活动的详细情况。利用一个临时的海底地震台网，我们对震源和一维速度模型进行了反演。一次系统搜索得出地壳厚度为27千米，反映了平均的弧和弧后结构。我们在马提尼克岛和多米尼克岛下方发现了大量的板内地震活动，这可能与俯冲的马拉松和/或墨丘利断裂带有关。寒冷的地幔楔角处普遍的地震活动以及俯冲板块界面深处的逆冲地震活动表明，一个异常宽的巨型逆冲发震带可达约65千米深度。我们的研究结果为未来了解东加勒比地区的区域地震危险性以及小安的列斯群岛弧下方的挥发物循环提供了一个极好的框架。
The Lesser Antilles arc is only one of two subduction zones where slow-spreading Atlantic lithosphere is consumed. Slow-spreading may result in the Atlantic lithosphere being more pervasively and heterogeneously hydrated than fast-spreading Pacific lithosphere, thus affecting the flux of fluids into the deep mantle. Understanding the distribution of seismicity can help unravel the effect of fluids on geodynamic and seismogenic processes. However, a detailed view of local seismicity across the whole Lesser Antilles subduction zone is lacking. Using a temporary ocean-bottom seismic network we invert for hypocenters and 1D velocity model. A systematic search yields a 27 km thick crust, reflecting average arc and back-arc structures. We find abundant intraslab seismicity beneath Martinique and Dominica, which may relate to the subducted Marathon and/or Mercurius Fracture Zones. Pervasive seismicity in the cold mantle wedge corner and thrust seismicity deep on the subducting plate interface suggest an unusually wide megathrust seismogenic zone reaching similar to 65 km depth. Our results provide an excellent framework for future understanding of regional seismic hazard in eastern Caribbean and the volatile cycling beneath the Lesser Antilles arc.