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利用1985~2010年跨龙门山断裂带南段的精密水准观测,并消除2008年汶川地震同震变形的影响,获取了龙门山断裂带南段震间期的地壳垂直形变场.结果表明,双石-大川断裂(龙门山前山断裂)和新开店断裂(大邑断裂南段)之间的芦山地块处于正、负垂直形变梯度带相交的区域,说明该区域在芦山地震前25年内已闭锁.根据2010~2013年穿过震区的水准观测数据,同时消除震前近3年的地壳垂直变形,得到了芦山地震同震垂向位移.同震位移场揭示距离震中最近的达多35水准点最大同震位移达到198.4 mm(相对马雅165基),西北盘(上盘)相对东南盘(下盘)向上运动,显示发震断层以逆冲错动为主.对比芦山地震垂向同震变形和震间期变形,可发现该地震符合弹性回跳学说,芦山地块震间期积累的弹性应变能(位移亏损)在震时得到弹性回跳释放.
The vertical crustal deformation of the crust in the southern segment of the Longmenshan fault zone was obtained by using the precise leveling observations across the southern segment of the Longmenshan fault zone from 1985 to 2010 and eliminating the influence of the coseismic deformation in the Wenchuan earthquake in 2008. The results show that the double- Lushan block between the Ochuan fault (the Longmenshan fault) and the Xinjiandian fault (the southern section of the Dayi fault) is in the intersection of positive and negative vertical deformation gradient zones, indicating that the area has been locked within 25 years before the Lushan earthquake. Based on the observed data of the earthquake-stricken areas during 2010-2013 and the vertical crustal deformation of the crust in the past 3 years, the crustal vertical deformation of the Lushan earthquake was eliminated, and the coseismic displacement field revealed the nearest Dada 35-level point The maximum coseismic displacement reaches 198.4 mm (relative to Mayan 165 base), and the upward movement of the northwest plate (upper plate) relative to the southeast plate (lower plate) shows that the seismogenic fault is dominated by thrusting and fault movement.Comparing with the vertical coseismicity of Lushan earthquake Deformation and deformation during the epicenter period show that the earthquake accords with the theory of elastic rebound. The elastic strain energy (displacement loss) accumulated in the Lushan block during the earthquake period can be released elastically during the earthquake.