2010年1月12日海地 Mw7.0地震InSAR同震形变观测及同震滑动分布反演

摘要

At 21 : 53 ( GMT) on Jan 12th ,2010 ,an MW 7. 1 earthquake struck Haiti with epicenter located at (72. 57°W.18. 44°N) . We derive the high precision Interferometric Synthetic Aperture Radar( InSAR)deformation field covering the whole rupture zone and use the observations to study the seismogenic kinematics of the quake. We analyze the influences of InSAR data errors , such as the orbit errors and atmospheric errors, on the ALOS PALSAR data and finally obtain the coseismic deformation field in the line of sight( LOS) direction. We invert the LOS displacement for the fault geometry of the seismogenic fault and its corresponding slip distribution. We find that the fault dips to the north at 37° , lower than the 70° north-dipping solution from USGS. To test other possible dipping angles of the fault plane and find the best estimate of the fault geometry , we construct an other two fault models. One is modeled with a 70° north-dipping fault plane and the other one is a listric fault model with the hinge depth inverted. Comparing the predicted InSAR interferogram of the three fault models with the observed InSAR coseismic data ,we argue that the model with 37° north dipping angle is more rational than the other two models. Our preferred model shows that the coseismic slip concentrates mainly at 4 ～ 16km depth,and the maximum slip is 2. 8m, appearing at 7. 2km depth. The coseismic displacement exhibits both reversal faulting and sinistral strike-slip, suggesting complex fault motion in this earthquake. The moment release of this earthquake is 5. 64×1019 Nm , equivalent to an MW 7. 1 earthquake .%2010年1月12日GMT时间21时53分,在海地境内(72.57°W,18.44°N)发生了Mw7.0地震.文中利用干涉合成孔径雷达(InSAR)方法获得了覆盖整个震区的高精度形变观测资料,用以研究该地震的发震机理.采用ALOs PALSAR数据,分析了轨道、大气等误差源对干涉信号的影响,最终获得了雷达视线向(LOS)的同震形变场.基于误差矫正后的InSAR同震数据,反演得到了发震断层的几何参数及断层面上的同震滑移分布.结果显示断层为N倾37°,小于USGS给出的断层倾角 70 °.为了测试断层倾角的最佳估计,另外建立了倾角为70°的平面断层模型,以及一种铲形断层模型.通过将不同模型预测的InSAR干涉图和InSAR同震观测数据对比.认为倾角为37°的断层模型更为合理.断层同震滑动主要分布在4～16km深度范围内,最大同震滑移量达2.8m,深度为7.2km.滑动主要表现为逆冲兼具左旋走滑2种方式,显示了此次地震非常复杂的运动特点.据此模型得到该地震释放的地震矩为5.64 × 1019Nm,对应矩震级为Mw 7.1.