Geodetic imaging of potential seismogenic asperities on the Xianshuihe-Anninghe-Zemuhe fault system, southwest China, with a new 3-D viscoelastic interseismic coupling model
Geodetic imaging of potential seismogenic asperities on the Xianshuihe-Anninghe-Zemuhe fault system, southwest China, with a new 3-D viscoelastic interseismic coupling model
复制标题
利用新的 3 维粘弹性震间耦合模型对中国西南部鲜水河-安宁河-则木河断裂系上潜在的孕震粗糙体进行大地测量成像
DOI：
10.1002/2014jb011492
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发表时间：
2015
影响因子：
3.9
通讯作者：
Xu Caijun
中科院分区：
文献类型：
--
作者：
Jiang Guoyan;Xu Xiwei;Chen Guihua;Liu Yajing;Fukahata Yukitoshi;Wang Hua;Yu Guihua;Tan Xibin;Xu Caijun
利用GPS和干涉合成孔径雷达(InSAR)观测资料，对鲜水河-安宁河-泽木河(XAZ)断裂系统震间耦合的空间变化进行了成像。建立了一种新的三维粘弹性震间变形模型，用三角位错斑块离散断层面上的块体旋转和应变速率、震后粘弹性松弛和震间滑动亏损。合成数据的反演表明，最优权重比和平滑因子均为1。不同粘度的大地测量数据的连续联合反演揭示了XAZ断裂系统上潜在的6个完全耦合的凹凸体。其中，已公布的微震深度剖面证实了1019pa S所不存在的石棉-冕宁之间的潜在凹凸体。此外，在道孚和康定之间还存在另一个潜在的部分耦合的凹凸体，其长度尺度可达14 0 Km。所有这些粗糙度都大于最小可分辨波长。磨溪镇附近的最小和最大滑动亏损率分别为7.00和12.7 mm/年。不同的粘性对滑动亏损率分布的粗糙度和拟合残差的影响很小，这可能表明我们的观测不能很好地约束中下地壳的粘性。各地震段的地震矩累积计算表明，松林口-色拉哈(S4)、石棉-冕宁(S7)和冕宁-西昌(S8)段与特征地震的破裂非常接近。然而，置信度水平受到稀疏的近断层观测的限制。
We use GPS and interferometric synthetic aperture radar (InSAR) measurements to image the spatial variation of interseismic coupling on the Xianshuihe‐Anninghe‐Zemuhe (XAZ) fault system. A new 3‐D viscoelastic interseismic deformation model is developed to infer the rotation and strain rates of blocks, postseismic viscoelastic relaxation, and interseismic slip deficit on the fault surface discretized with triangular dislocation patches. The inversions of synthetic data show that the optimal weight ratio and smoothing factor are both 1. The successive joint inversions of geodetic data with different viscosities reveal six potential fully coupled asperities on the XAZ fault system. Among them, the potential asperity between Shimian and Mianning, which does not exist in the case of 1019Pa s, is confirmed by the published microearthquake depth profile. Besides, there is another potential partially coupled asperity between Daofu and Kangding with a length scale up to 140 km. All these asperity sizes are larger than the minimum resolvable wavelength. The minimum and maximum slip deficit rates near the Moxi town are 7.0 and 12.7 mm/yr, respectively. Different viscosities have little influence on the roughness of the slip deficit rate distribution and the fitting residuals, which probably suggests that our observations cannot provide a good constraint on the viscosity of the middle lower crust. The calculation of seismic moment accumulation on each segment indicates that the Songlinkou‐Selaha (S4), Shimian‐Mianning (S7), and Mianning‐Xichang (S8) segments are very close to the rupture of characteristic earthquakes. However, the confidence level is confined by sparse near‐fault observations.