九寨沟7.0级地震前地壳水平形变状态与变化

The horizontal crust deformation state and its variation before the MS7.0 earthquake in Jiuzhaigou of Sichuan

摘要:

利用1999～2015年流动GNSS观测资料及处理结果，分析了九寨沟M_S7.0地震前区域水平形变场及其变化，得到以下认识：①九寨沟M_S7.0地震震源区在汶川8.0级地震之前为右旋剪切形变，汶川地震之后为左旋剪切形变；②2011年以来震源区左旋剪切形变持续较弱，较大的左旋剪切形变位于其西南；③震源区最大剪切应变、最大主应变、最小主应变均较弱；④九寨沟地震的发生与汶川地震的发生与否有一定的关系方面，龙门山断裂带的活动处在闭锁时段时则有所抑制或推迟九寨沟地震的发生，汶川地震后龙门山断裂带一定程度的解锁则有助于九寨沟地震的发生或促使发震时刻有所提前；⑤距震中近70km的SCSP站出现了7.1mm的南向同震位移，其他连续站未发现同震位移。

Abstract:

The regional horizontal deformation field and its variation around the epicenter area of the M_S7.0 strong earthquake in Jiuzhaigou, Sichuan was analyzed with the campaign GNSS observation data from 1999 to 2015, and the following views were obtained:① The hypocentral region of the M_S7.0 strong earthquake in Jiuzhaigou of Sichuan was deformed with dextral shear before the Wenchuan earthquake, and deformed with sinistral shear after the Wenchuan earthquake. ② The sinistral shear deformation in the hypocentral region has been weak since 2011, and the larger sinistral shear deformation is located in the southwest. ③The maximum shear strain, the maximum and minimum principal strains are weak in the hypocentral region. ④The occurrence of the Jiuzhaigou strong earthquake has a certain relationship with the extraordinary Wenchuan earthquake. The occurrence of the strong earthquake would be suppressed or postponed when the activity of the Longmenshan fault was locked, and the occurrence of the strong earthquake would be promoted or advanced when the activity of the Longmen fault was completely unlocked. ⑤ The southward coseismic displacement of 7.1mm occurred at the SCSP, the nearest station about 70km from the epicenter, but no coseismic displacement has been found at other continuous stations.