基于敏感性迭代拟合算法反演汶川Mw8．0地震InSAR同震形变场

Inversion of the Coseismic Deformation of the Mw8.0 Earthquake Derived from InSAR Technology Using Sensitivity-based Iterative Fitting Method

基于单一断层模型，运用敏感性迭代拟合算法反演了汶川地震InsAR同震形变场，获得了断层滑动分布及部分震源参数。结果表明，倾角线性变换的单断层模型模拟的同震形变场与InSAR形变场吻合较好．且残差较小，平均残差为0．11m；反演的滑动分布主要集中于地下0～20km．其中．汶川地区在震源深度附近有较大的滑动量，10～15km深度最高可达7m。地表滑动量却相对较小，平均值仅为2．5m，平均滑动角均值约为121°；北川地区最大滑动量可达到10m，平均滑动角均值约为109°；而青川地区10～15km深度滑动量最高也达8m，平均滑动角均值约为135°；滑动矢量图显示，沿SWNE走向断层面的滑动方向以强烈的逆冲为t，兼有一定有旋走滑分量。反演矩张量为1．0×10^21N·m，矩震级达Mw8．0。

Using single fault model, we modeled the co-seismic deformation of the Wenchuan earthquake derived from InSAR technology. The one-segment fault model with uniform dip angle of 33° cannot explain the InSAR data, with a large residual of 0. 1243 m. Our favored fault model is one-segment fault model with linear varied dip from 88° to 33°. The simulated deformation by forward modeling are matched very well to the InSAR data with a relatively small RMS of 0. 11 m. The inverted slip distribution is concentrated on the depth of 0-20 km and the maximum slip is 10 m, with a relative high-resolution of spatial sampling against the results from seismological inversion. The largest slip occurred under the Wenchuan , Beichuan and Qingchuan areas. The epicentral area of Wenchuan has a relatively large distributed slip and has the largest slip of 7 m at the depth 10-20 km, but has a relatively small mean slip of 2.5 m at the depth of 0-10 km, with a mean inverted rake of 121° on the fault surface. Beichuan area has relatively more concentrated distributed slip and shallower depth than other areas. This may be the deep cause by which the Beichuan area was the most severely destroyed area, with the largest slip of 10 m and mean rake of 109°. Qingchuan area has a largest slip of 8m at the depth of 10-15 km and a mean slip of 5m at the depth of 0-10 km, with a mean rake of 135°. Large slip and concentrated distribution are consistent with the fact that there were many aftershocks several months after the main shock at this area. The inverted rake distribution shows that it is mainly reverse and has some right-lateral slip on the entire fault surface. The inverted seismic moment tensor M0 is 1.0× 10^21 N · m, and the inverted moment magnitude scale Mw is 8.0.