【摘要】 2017年8月8日我国四川九寨沟发生里氏7.0级地震.本研究利用基线校正方法获得距震中100km范围内9个强震台站同震位移,基于Sentinel-1卫星干涉SAR影像对获取了InSAR同震形变场.结合GPS形变数据,本研究进行了震源滑动模型联合反演,结果显示此次地震整体以走滑运动为主,释放地震矩约为7.60×1018 N·m(～MW6.52).通过对比模拟形变场和观测值显示,联合反演结果优于单独基于InSAR形变场的反演结果.静态应力变化计算结果显示断层平均静态应力降为1.07MPa.反演滑动模型沿走向和倾角方向拐角波数值分别为0.99×10-4和1.10×10-4.同震静态库仑应力变化计算结果显示共有83.6%的余震位于库仑应力增加的区域,被主震所触发的余震占总数的77.9%,主震对后续余震具有显著触发作用.强地面运动模拟结果显示模拟结果在烈度分布范围和等级方面与调查烈度符合度很高,模拟结果能够很好地反映断层破裂的方向性效应等特征.本研究计算结果显示九寨沟地震无论是平均静态应力降还是拐角波数均低于同类型地震的平均水平,这可能是造成本次地震强地震动水平相对不高的原因.更多还原

【Abstract】 On August 8,2017,an earthquake of MS7.0 occurred at Jiuzhaigou,China.Based on the baseline correction method,coseismic displacement of 9 strong motion stations 100 km away from the epicenter are obtained.Also,the InSAR coseismic deformation field is derived from the Sentinel-1 satellite interference SAR images.Combined with GPS data,ajoint inversion for the slip model of the source fault is carried out.Results show that the fault is dominated by strikeslip,and the total released seismic moment is about 7.60×1018 N·m,equivalent to an earthquake of MW6.52.Results also demonstrate the joint inversion is better than the inversion from InSAR deformation alone comparing the simulated and the observed deformation field.Static stress calculation shows that the average static stress drop is 1.07 MPa,and corner wavenumbers of the slip model are 0.99×10-4 and 1.10×10-4 in strike and dip directions,respectively.Coulomb stress change calculation reveals that 83.6% of aftershocks are located in the positive Coulomb stress zone,77.9% of total aftershocks may be triggered by the mainshock,indicating that the mainshock has a significant triggering effect on the subsequent aftershocks.The strong motion simulations permit to display basic features associated with the ground motion patterns.Moreover,the simulated results reflect the obvious rupture directivity effect.Both the average stress drop and corner wavenumber are at low levels which may be responsible for relatively weaker ground motion during the Jiuzhaigou earthquake.更多还原