Interseismic and Postseismic Shallow Creep of the North Qaidam Thrust Faults Detected with a Multitemporal InSAR Analysis
Interseismic and Postseismic Shallow Creep of the North Qaidam Thrust Faults Detected with a Multitemporal InSAR Analysis
复制标题
DOI：
10.1029/2019jb017692
复制
发表时间：
2019-07
期刊：
影响因子：
--
通讯作者：
S. Daout;H. Sudhaus;T. Kausch;A. Steinberg;Benedetta Dini
中科院分区：
文献类型：
--
作者：
S. Daout;H. Sudhaus;T. Kausch;A. Steinberg;Benedetta Dini
了解地震周期产生褶皱和容纳缩短的机制对于量化活动断层的地震潜力和将地震滑动整合到我们对长期变形的物理机制的理解中至关重要。然而，由于相对于噪声振幅的低运动速率，目前的空间大地测量技术在山区测量如此小的变形信号是具有挑战性的。2003年至2009年间发生了2次地震。我们报告了在短波长处地震滑动抬升增厚地壳的各种情况。我们提供了一个罕见的陡、浅、长13公里、宽6公里的余震信号的例子，该信号在空间上与背斜重合，并持续到2011年，以响应2003年的6.3 Mw事件。我们认为，2003年地震期间的埋藏地震滑动触发了浅层逆冲构造的塑性和弹性褶皱和地震滑动。我们建立了2003年地震后地表位移的一阶二维模型，并突出了三个断层块上的分段滑动，这些断层块在接近地表时变陡。本研究强调了浅层地震滑动在逆冲和褶皱的长期和永久变形中的基本作用，以及干涉合成孔径雷达在探测和表征大山区地震滑动时空行为方面的潜力。
Understanding the mechanisms by which earthquake cycles produce folding and accommodate shortening is essential to quantify the seismic potential of active faults and integrate aseismic slip within our understanding of the physical mechanisms of the long‐term deformation. However, measuring such small deformation signals in mountainous areas is challenging with current space‐geodesy techniques, due to the low rates of motion relative to the amplitude of the noise. Here we successfully carry out a multitemporal Interferometric Synthetic Aperture Radar analysis over the North Qaidam fold‐thrust system in NE Tibet, where eight Mw> 5.2 earthquakes occurred between 2003 and 2009. We report various cases of aseismic slip uplifting the thickened crust at short wavelengths. We provide a rare example of a steep, shallow, 13‐km‐long and 6‐km‐wide afterslip signal that coincides spatially with an anticline and that continues into 2011 in response to a Mw 6.3 event in 2003. We suggest that a buried seismic slip during the 2003 earthquake has triggered both plastic an‐elastic folding and aseismic slip on the shallow thrusts. We produce a first‐order two‐dimensional model of the postseismic surface displacements due to the 2003 earthquake and highlight a segmented slip on three fault patches that steepen approaching the surface. This study emphasizes the fundamental role of shallow aseismic slip in the long‐term and permanent deformation of thrusts and folds and the potential of Interferometric Synthetic Aperture Radar for detecting and characterizing the spatiotemporal behavior of aseismic slip over large mountainous regions.