Interseismic and coseismic displacements of the Lushan Ms 7.0 earthquake inferred from leveling measurements  

作　　者：Ming Hao Qingliang Wang Liwei Liu Qi Shi 

机构地区：[1]Second Monitoring Center,China Earthquake Administration [2]Geodetic Data Processing Center,National Administration of Surveying,Mapping and Geoinformation

出　　处：《Chinese Science Bulletin》2014年第35期5129-5135,共7页

基　　金：supported by National Special Fund for Earthquake Scientific Research in Public Interest(201408014,201208009);the National Natural Science Foundation of China(41174083)

摘　　要：By using precise leveling data observed between 1985 and 2010 across the south section of the Longmenshan fault zone,and eliminating the coseismic displacements caused by the Wenchuan Ms 8.0 earthquake,the interseismic vertical deformation field was obtained.The result shows that the Lushan region,located between the Shuangshi–Dachuan fault(front range of the Longmenshan fault) and the Xinkaidian fault(south section of the Dayi fault),is situated in the intersection zone of positive and negative vertical deformation gradient zones,indicating that this zone was locked within 25 years before the Lushan earthquake.Based on leveling data across the rupture zone surveyed between 2010 and 2013,and by eliminating the vertical deformation within 3 years before the earthquake,the coseismic vertical displacement was derived.The coseismic vertical displacement for the benchmark DD35,which is closest to the epicenter,is up to198.4 mm(with respect to MY165A).The coseismic displacement field revealed that the northwest region(hanging wall) moved upwards in comparison with the southeastern region(foot wall),suggesting that the seismogenic fault mainly underwent thrust faulting.By comparing the coseismic and interseismic vertical deformation fields,it was found that the mechanisms of this earthquake are consistent with the elastic rebound theory; the elastic strain energy(displacement deficit) accumulated before the Lushan earthquake was released during this quake.By using precise leveling data observed between 1985 and 2010 across the south section of the Longmenshan fault zone, and eliminating the coseismic displacements caused by the Wenchuan Ms 8.0 earthquake, the interseismic vertical deformation field was obtained. The result shows that the Lushan region, located between the Shuangshi-Dachuan fault （front range of the Long- menshan fault） and the Xinkaidian fault （south section of the Dayi fault）, is situated in the intersection zone of positive and negative vertical deformation gradient zones, indicating that this zone was locked within 25 years before the Lushan earthquake. Based on leveling data across the rupture zone surveyed between 2010 and 2013, and by eliminating the vertical deformation within 3 years before the earthquake, the coseismic vertical displacement was derived. The coseismic vertical displacement for the benchmark DD35, which is closest to the epicenter, is up to 198.4 mm （with respect to MY165A）. The coseismic dis- placement field revealed that the northwest region （hanging wall） moved upwards in comparison with the southeastern region （foot wall）, suggesting that the seismogenic fault mainly underwent thrust faulting. By comparing the coseismic and interseismic vertical deformation fields, it was found that the mechanisms of this earthquake are consistent with the elastic rebound theory; the elastic strain energy （displacement deficit） accumulated before the Lu- shan earthquake was released during this quake.

关 键 词：同震位移 测量数据 地震前 庐山 龙门山断裂带 弹性应变能 垂直变形 发震断层 

分 类 号：P315[天文地球—地震学]