The 2016 Mw 6.5 Nura earthquake in the Trans Alai range, northern Pamir: Possible rupture on a back-thrust fault constrained by Sentinel-1A radar interferometry
The 2016 Mw 6.5 Nura earthquake in the Trans Alai range, northern Pamir: Possible rupture on a back-thrust fault constrained by Sentinel-1A radar interferometry
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2016 年帕米尔北部跨阿莱山脉发生的 6.5 级努拉地震：Sentinel-1A 雷达干涉测量限制的逆冲断层可能发生破裂
DOI：
10.1016/j.tecto.2018.10.025
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发表时间：
2018
期刊：
影响因子：
2.9
通讯作者：
Ping He
中科院分区：
文献类型：
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作者：
Ping He
2016年6月26日，跨阿莱山脉发生了6.5级地震，距离2008年发生的6.7级地震约37 公里，都在中国努拉镇附近。我们使用来自Sentinel-1A的干涉合成孔径雷达（InSAR）图像来成像最近一次Nura地震的同震地表位移。我们反演了断层几何形状和滑动分布的干涉图。我们发现InSAR数据既可以用陡北倾断层来描述，也可以用浅南倾断层来描述，尽管只有当南倾断层的滑动被约束为盲时才可以。北倾断裂面InSAR失配值略低，北倾断裂面较好地描述了近场形变梯度。2016年努拉地震首选北倾断层几何形态（~67°倾角，266°走向）作为震源，不仅与InSAR拟合更好，而且得到的同震滑动模型更符合震源机制解和区域发震厚度；然而，重要的是要重申，InSAR数据不能唯一地确定哪种模型是Nura地震的最终代表。在Trans Alai范围下~14 km深度处，推断的最大同震滑动约为0.75 m，最大滑动约为8-20 km深度。滑动不到达地表，主要由带右侧走滑分量的逆冲位移控制。我们优选的滑移模型的大地力矩为6.61 × 1018N·m，相当于Mw 6.5。我们优选的断层的地表投影位于帕米尔锋面逆冲（PFT）的南部，我们认为它是列表型PFT的逆冲，这表明跨阿莱山脉是一个“弹出”构造。
On June 26, 2016 an Mw 6.5 earthquake occurred in the Trans-Alai Range, about 37 km west of a 2008 Mw 6.7 earthquake, both near the town of Nura, China. We use Interferometric Synthetic Aperture Radar (InSAR) images from Sentinel-1A to image coseismic surface displacements from the most recent Nura earthquake. We invert the interferograms for both fault geometry and slip distribution. We find that the InSAR data can be described by either a steeply north-dipping fault or shallowly south-dipping fault, although only when slip on the south-dipping fault is constrained to be blind. The InSAR misfit for the north-dipping fault plane is slightly lower, and the north-dipping fault better describes the gradient of deformation in the near-field. We prefer the north-dipping fault geometry (~67° dip and 266° strike) as the source for the 2016 Nura earthquake, not only due to the better fit to the InSAR, but the resulting coseismic slip model is more consistent with the focal mechanism solutions and regional seismogenic thickness; however, it is important to reiterate that the InSAR data cannot uniquely determine which model is the definitive representation of the Nura earthquake. The maximum inferred coseismic slip is about 0.75 m at ~14 km depth beneath the Trans Alai range, with the largest slip in the depth range of about 8–20 km. Slip does not reach the surface, and is dominated by thrust displacement with a right-lateral strike-slip component. The geodetic moment of our preferred slip model is 6.61 × 1018N·m, equivalent to Mw 6.5. The surface projection of our preferred fault is to the south of the Pamir Frontal Thrust (PFT), and we argue it is a back-thrust of the listric PFT, suggesting that the Trans Alai range is a ‘pop-up’ structure.