摘要:
通过对2013年"4.20"四川芦山地震前后GPS观测数据的处理,得到地震周围地区GPS测站同震位移及速度矢量场。GPS测站同震位移大小为5.09~51.05mm,平均为14.18mm;GPS测站运动速度为2.64~52.37mm/a,平均为18.89mm/a。利用断裂两侧GPS测站速度矢量差得到了龙门山断裂带南段次级断裂的运动速度,龙门山断裂带南段的后山断裂、中央断裂、前山断裂运动速度大小分别为49.66 ±3.90mm/a、79.58 ±3.33mm/a、50.94 ±3.91/a;中央断裂以右旋挤压为主,而后山断裂、前山断裂表现为左旋拉张的特性。综合分析表明,芦山地震是发生在龙门山断裂带南段东南侧的逆冲型地震,发震构造为前山断裂与新津断裂之间的小断层。芦山地震对周围地区的影响不大,主要集中在龙门山断裂带南段及震中附近区域。
Abstract:
Based on discontinuous GPS data from the micro-earthquake observatories before and after the Lushan earthquake in 2013, the coseismic displacement and velocity vector fields have been obtained around the Lushan focal area, western Sichuan. The coseismic displacement values range between 5.09 and 51.05 mm, with an average of 14.18 mm, and the movement velocities vary from 2.64 to 52.37 mm/a, with an average of 18.89 mm/a. Furthermore, the movement velocities of the secondary faults in the southern part of the Longmenshan fault zone have also been obtained in the light of velocity vector differences, including 49.66 ±3.90 mm/a for the back range fault, 79.58 ±3.33 mm/a for the central fault and 50.94 ±3.91 mm/a for the front range fault. The central fault exhibits dextral compressional movement, whereas the back range and front range faults display sinistral extensional movement. The authors conclude that the Lushan earthquake in 2013 may be interpreted as a thrusting event on the southeastern side of the southern part of the Longmenshan fault zone. The seismogenic structures are represented by the minor faults between the front range fault and Xinjin fault. The Lushan earthquake in 2013 only had an important effect on the southern part of the Longmenshan fault zone and the areas around the Lushan focal area.
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