海城盖州地区速度结构和震源位置的联合反演研究
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摘要
2012年2月至2013年4月在辽宁盖州地区连续发生了5次4级左右地震,分别为2012年2月2日ML4.7、4.2地震、7月12日ML4.2地震11月1日ML4.0地震以及2013年3月30日ML4.0级地震,地震序列大致呈NW向分布。利用2008年以来盖州地区和海城-岫岩地区的地震观测数据,采用震源位置和速度结构联合反演的软件包Simulps14,给出了两个地区的小震精定位结果和三维速度结构。发现盖州地区震群发生位置较浅,且随时间向西北向展布;其地下速度结构与海城地区地下速度结构存在一定的相似性,分析认为盖州震群是发生在一条类似于大洋河断裂但规模较小的新的断裂带上。
There are several ML4.0 earthquakes occurred in the Gaizhou area,Liaoning province from Feb.2,2012 to Apr.30,2013.This earthquake sequence shows a roughly NW-trending distribution.We use earthquake observation reports recorded by regional seismic stations during the period from 2008 to 2013.Through simultaneous inversion method of earthquake hypocenters and velocity structure,we got the earthquake location and velocity structure of Gaizhou and Haicheng area by software Simulps 14.The result of earthquake location shows that Gaizhou earthquake warm occurred in a shallower depth,and over time,to the northwest trending.The Gaizhou's underground velocity structure is similar to Haicheng's underground velocity structure.We think that the Gaizhou earthquake swarm occurred in a new and smaller fault similar to the Dayanghe fault.
There are several ML4.0 earthquakes occurred in the Gaizhou area,Liaoning province from Feb.2,2012 to Apr.30,2013.This earthquake sequence shows a roughly NW-trending distribution.We use earthquake observation reports recorded by regional seismic stations during the period from 2008 to 2013.Through simultaneous inversion method of earthquake hypocenters and velocity structure,we got the earthquake location and velocity structure of Gaizhou and Haicheng area by software Simulps 14.The result of earthquake location shows that Gaizhou earthquake warm occurred in a shallower depth,and over time,to the northwest trending.The Gaizhou's underground velocity structure is similar to Haicheng's underground velocity structure.We think that the Gaizhou earthquake swarm occurred in a new and smaller fault similar to the Dayanghe fault.
引文
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[14]Jacob K H.Three dimensional seismic ray tracing in a laterally heterogeneous spherical earth[J].J Geophys Res,1970,75:6675-7789.
[15]Thurber C H,Atre S R.Three-dimensional vP/vSvariations along the Loma Prieta rupture zone[J].Bull Seism Soc Am,1993,83:717-736.
[16]Humphreys and Clayton.Adaptation of tomographic reconstruction to seismic travel time problems[J].Journal of Geophysical Research,1988,93:1073-1085.
[17]卢造勋.中朝地台东北缘地区的地震层析成像[J].地球物理学报,2002,45(3):338-351.
[2]马胜利,邓志辉,马文涛.雁列式断层过程中物理场演化的实验研究[J].地震地质,1995,17(4):327-341.
[3]蒋海昆,马胜利,张流.雁列式断层组合变形过程中的声发射活动特征[J].地震学报,2002,24(4):385-396.
[4]Aki K,Lee W H K.Determination of three-dimensional velocity anomalies under a seismic array using P arrival times from local earthquakes.1.A homogeneous initial model[J].J Geophys Res,1976,81:4381-4399.
[5]Um J,Thurber C H.A fast algorithm for two-point seismic ray tracing[J].Bull Seism Soc Am,1987,77:972-986.
[6]Zhao D,Hasegawa A,Horiuchi S.Tomographic imaging of P and S wave velocity structure beneath northeastern Japen[J].J Geophys Res,1992,97:19909-19928.
[7]李志伟,胥颐,郝天珧.环渤海地区的地震层析成像与地壳上地幔结构[J].地球物理学报,2006,49(3):797-804.
[8]Pavlis G L.Appraising earthquake hypocenter location errors:a complete,practical approach for single-event locations[J].Bull Seism Soc Am,1986,76,1699-171.
[9]Geiger L.Probability method for the determination of earthquake epicenters from arrival time only[J].Bull St Louis Univ,1912,8:60-71.
[10]Zhang H,Thurber C.Double-difference Tomography:the method and its application to the Hayward Fault,California[J].Bull Seism Soc Am,2003,93:1875-1889.
[11]Thurber C H.Earthquake locations and three-dimensional crustal structure in the Coyote late area,Central California[J].J Geophys Res,1983,88:8226-8236.
[12]刘福田.震源位置和速度结构的联合反演(l)—理论和方法[J].地球物理学报,1984,27(2),167-175.
[13]Kissling E,Ellsworth W L,Eberhard-Phillips D,et al.Initial reference models in local earthquake tomography[J].J Geophys Res,1994,99:19635-19646.
[14]Jacob K H.Three dimensional seismic ray tracing in a laterally heterogeneous spherical earth[J].J Geophys Res,1970,75:6675-7789.
[15]Thurber C H,Atre S R.Three-dimensional vP/vSvariations along the Loma Prieta rupture zone[J].Bull Seism Soc Am,1993,83:717-736.
[16]Humphreys and Clayton.Adaptation of tomographic reconstruction to seismic travel time problems[J].Journal of Geophysical Research,1988,93:1073-1085.
[17]卢造勋.中朝地台东北缘地区的地震层析成像[J].地球物理学报,2002,45(3):338-351.