Aseismic zone and earthquake segmentation associated with a deep subducted seamount in Sumatra
Aseismic zone and earthquake segmentation associated with a deep subducted seamount in Sumatra
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DOI：
10.1038/ngeo1119
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发表时间：
2011-05
影响因子：
18.3
通讯作者：
Satish C. Singh;N. Hananto;Maruf Mukti;David P. Robinson;Shamita Das;A. Chauhan;H. Carton;B. Gratacos;Stephan Midnet;Y. Djajadihardja;H. Harjono
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文献类型：
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作者：
Satish C. Singh;N. Hananto;Maruf Mukti;David P. Robinson;Shamita Das;A. Chauhan;H. Carton;B. Gratacos;Stephan Midnet;Y. Djajadihardja;H. Harjono
海山等大型地形特征的俯冲与俯冲带的板块锁定、地震发生和分割以及地壳侵蚀有关。然而，俯冲特征在产生巨型逆冲断层地震中的作用一直难以辨别，因为传统的成像技术仅限于地壳上部12公里，而这些破裂起始于20-40公里深处（参考文献）。在这里，我们使用低能量源的深穿透成像技术，以确定一个高3-4公里、宽40公里的海山，该海山已俯冲到苏门答腊弧前地幔以下30-40公里的深度。我们发现，尽管有160多公里的俯冲，海山仍然保持完整，而且海山之上或之下都没有地震活动。因此，我们认为海山与逆冲板块之间的耦合是弱的和不稳定的。我们认为，俯冲的地形特征，如海山可能会导致俯冲带的分割，这反过来又可以减少在这些地方的大规模地震的最大规模。
The subduction of large topographic features such as seamounts has been linked to plate locking,,,,,,, earthquake generation and segmentation, as well as crustal erosion,,at subduction zones. However, the role of subducted features in the generation of megathrust earthquakes has been difficult to discern because traditional imaging techniques are limited to the upper 12 km of the Earth’s crust, whereas these ruptures initiate at depths of 20–40 km (ref. ). Here we use a deeply penetrating imaging technique with a low-energy source to identify a seamount 3–4 km high and 40 km wide that has been subducted to a depth of 30–40 km below the Sumatra forearc mantle. We find that the seamount has remained intact despite more than 160 km of subduction, and that there is no seismic activity either above or below the seamount. We therefore conclude that the coupling between the seamount and overriding plate is weak and aseismic. We suggest that the subduction of a topographic feature such as a seamount could lead to the segmentation of the subduction zone, which could in turn reduce the maximum size of megathrust earthquakes in these localities.