Finite‐fault slip model of the 2016 Mw 7.5 Chiloé earthquake, southern Chile, estimated from Sentinel‐1 data
Finite‐fault slip model of the 2016 Mw 7.5 Chiloé earthquake, southern Chile, estimated from Sentinel‐1 data
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DOI：
10.1002/2017gl073560
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发表时间：
2017-05
影响因子：
5.2
通讯作者：
Wenbin Xu
中科院分区：
文献类型：
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作者：
Wenbin Xu
智利俯冲带的俯冲地震已被广泛研究，但发生在其南部的地震吸引了较少的研究兴趣，主要是由于其较低的地震活动率。在这里，我使用Sentinel‐1干涉合成孔径雷达（干涉合成孔径雷达）数据和距离偏移测量生成2016年智利南部Mw7.5 Chiloé地震的同震地壳形变图。我发现一个集中的地壳变形与地面位移约50厘米在南部的奇洛埃岛。最佳拟合的断层模型显示，在NNE 4°的浅倾角平面上存在纯逆冲断层运动。干涉合成孔径雷达确定的力矩为2.4 × 1020 Nm，剪切模量为30 GPa，相当于Mw 7.56，略低于地震力矩。该模型表明，滑动没有达到沟槽，它重新破裂的断层，在1960年Mw 9.5地震破裂的一部分。2016年的地震只释放了1960年破裂带上积累的一小部分应变能，这表明智利南部未来发生大地震的地震危险性很高。
Subduction earthquakes have been widely studied in the Chilean subduction zone, but earthquakes occurring in its southern part have attracted less research interest primarily due to its lower rate of seismic activity. Here I use Sentinel‐1 interferometric synthetic aperture radar (InSAR) data and range offset measurements to generate coseismic crustal deformation maps of the 2016 Mw 7.5 Chiloé earthquake in southern Chile. I find a concentrated crustal deformation with ground displacement of approximately 50 cm in the southern part of the Chiloé island. The best fitting fault model shows a pure thrust‐fault motion on a shallow dipping plane orienting 4° NNE. The InSAR‐determined moment is 2.4 × 1020 Nm with a shear modulus of 30 GPa, equivalent to Mw 7.56, which is slightly lower than the seismic moment. The model shows that the slip did not reach the trench, and it reruptured part of the fault that ruptured in the 1960 Mw 9.5 earthquake. The 2016 event has only released a small portion of the accumulated strain energy on the 1960 rupture zone, suggesting that the seismic hazard of future great earthquakes in southern Chile is high.