Active Tectonics Around Almaty and along the Zailisky Alatau Rangefront
Active Tectonics Around Almaty and along the Zailisky Alatau Rangefront
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DOI：
10.1002/2017tc004657
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发表时间：
2017-10
期刊：
影响因子：
4.2
通讯作者：
C. Grützner;R. Walker;K. Abdrakhmatov;A. Mukambaev;A. Elliott;J. Elliott
中科院分区：
文献类型：
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作者：
C. Grützner;R. Walker;K. Abdrakhmatov;A. Mukambaev;A. Elliott;J. Elliott
Zailisky Alatau是哈萨克斯坦南部的一个超过250公里长的山脉。它的北方山脉周围的主要城市阿拉木图有超过4公里的地形起伏，但在天山其他大的山脉相比，很少有人知道其晚第四纪构造活动，尽管在历史记录中的几个破坏性的地震。我们使用野外观测、断层陡坎的差分GPS测量、历史和近期卫星图像、来自立体卫星图像的米级地形以及来自无人机调查的分米级高程模型来分析岭前断层的构造地貌。冲积扇中的断层陡坎高度从~2 m到>20 m不等，表明自末次盛冰期以来，地表破裂地震沿着岭前断层发生。这些地震的最小估计震级为M6.8-7。放射性碳测年结果表明，全新世的滑动速率约为1.2- 2.2mm/a。我们发现更多的证据，活跃的构造变形所有沿着阿拉木图山脉，盆地在哈萨克斯坦的平台，并在内部的Zailisky山脉。我们的数据表明，阿拉木图面临的地震危险来自各种来源，我们强调与城市发展到黄土覆盖的山麓和次生地震影响有关的问题。我们的结构和地质年代框架，我们提出了一个示意图的阿拉木图山脉，可能适用于类似的设置构造缩短在中亚山脉的演变。
The Zailisky Alatau is a >250 km long mountain range in Southern Kazakhstan. Its northern rangefront around the major city of Almaty has more than 4 km topographic relief, yet in contrast to other large mountain fronts in the Tien Shan, little is known about its Late Quaternary tectonic activity despite several destructive earthquakes in the historical record. We analyze the tectonic geomorphology of the rangefront fault using field observations, differential GPS measurements of fault scarps, historical and recent satellite imagery, meter‐scale topography derived from stereo satellite images, and decimeter‐scale elevation models from unmanned aerial vehicle surveys. Fault scarps ranging in height from ~2 m to >20 m in alluvial fans indicate that surface rupturing earthquakes occurred along the rangefront fault since the Last Glacial Maximum. Minimum estimated magnitudes for those earthquakes are M6.8–7. Radiocarbon dating results from charcoal layers in uplifted river terraces indicate a Holocene slip rate of ~1.2–2.2 mm/a. We find additional evidence for active tectonic deformation all along the Almaty rangefront, basinward in the Kazakh platform, and in the interior of the Zailisky mountain range. Our data indicate that the seismic hazard faced by Almaty comes from a variety of sources, and we emphasize the problems related to urban growth into the loess‐covered foothills and secondary earthquake effects. With our structural and geochronologic framework, we present a schematic evolution of the Almaty rangefront that may be applicable to similar settings of tectonic shortening in the mountain ranges of Central Asia.