Abstract: This study focuses on four moderate-sized earthquakes in the northern margin of the Qaidam Basin, northeastern Tibet Plateau, China, of which one occurred in 2008, and three in 2009, respectively. We obtain coseismic displacement fields of these four events using Envisat descending ASAR data and D-InSAR technology. The results show that the 2008 earthquake has only one deformation center and the 2009 earthquakes have three deformation centers in their fields. The maximum displacement of 2008 and 2009 earthquakes are 0.097m and 0.41m in the LOS(line of sight), respectively. We invert ground displacements of these earthquakes based on elastic dislocation models to estimate slip distribution on fault planes. For the 2008 event, using a one-segment fault model, the inversion reveals peak slip of about 0.47m occurring at a depth of 19km. For the 2009 earthquakes, the ground displacement pattern observed by InSAR can be fitted by a three-segment fault model with smallest RMS of residuals. The three sectional fault model is considered the most reliable.

Key words: Qaidam Basin, InSAR deformation, slip inversion

摘要： 对发生在青藏高原东北缘-柴达木盆地北缘的4个中等震级地震分别做了研究，其中1个地震发生在2008年，另外3个发生在2009年。利用D-InSAR技术采用Envisat ASAR降轨数据获得了这4个地震的同震形变场。结果显示，2008年地震形变场只有1个形变中心，而2009年地震有3个形变中心。2008、2009年地震引起的卫星视线向最大形变分别为0.097m和0.41m。基于弹性半空间模型和InSAR获得的地表形变场，反演了断层面滑动分布。对于2008年地震，采用了一分段断层模型，反演结果得出最大滑动为0.47m，发生在地下19km处。对于2009年发生的3个地震，结合分析InSAR同震形变场后分别采用了一分段断层、两分段断层和三分段断层模型反演，结果得出三分段断层模型模拟的形变场最符合观测到的InSAR地表形变场且残差最小，认为三分段断层模型最可靠。

关键词: 柴达木盆地, InSAR形变, 滑动反演