晋江外海沉积层上地壳速度结构的二维层析成像  

2D tomography of velocity structure of the sediment and upper crust off the coast of Jinjiang

作　　者：王笋[1] 谢志招[1] 张艺峰[1] 闫培[1] 

机构地区：[1]福建省地震局厦门地震勘测研究中心

出　　处：《地球物理学进展》2015年第1期106-110,共5页Progress in Geophysics

基　　金：福建省地震局青年科技基金(Y201407)资助

摘　　要：福建省地震局2013年在晋江外海成功实施了一条人工地震探测剖面(HX9,台湾海峡西部地壳深部结构探测计划的第一条测线).为反演沿测线的沉积层上地壳二维速度结构,我们收集了海底地震仪和陆地地震仪记录的4817个初至波走时数据,运用最大速度梯度射线追踪方法和联合迭代重建技术,建立了较为可靠、精细的二维P波波速模型.反演结果显示测线表层速度有很大的横向变化,据此推测晋江沿海5 km以内为岩浆岩出露,5 km外为沉积岩覆盖;基底面总体向东南方向倾斜,中西段埋深约为1600 m,在桩号60 km附近急剧下降;在测线上滨海断裂带表现为倾向东南的张性正断层,位于晋江市东南约50 km处,是闽浙沿海变质带和厦澎断陷的边界断裂.A seismic survey（HX9,the first profile of West Taiwan Strait Seismic Experiment） was carried out in 2013 off the coast of Jinjiang under the direction of Earthquake Administration of Fujian Province,CEA.To construct a 2D high resolution seismic tomography model for the sediment and upper crust in this seismic profile,we picked 4817 first-arrival times in the data recorded by ocean bottom seismometers and portable seismographs.In this paper the first break travel paths were traced using gradient search method and the inverse problem was solved based on Simultaneous Iterative Reconstruction Techniques（SIRT）.The inversion result revealed that the near-surface velocity vary from over 4000 m/s at the west end of the section to 1800 m/s in the eastern section.So we indicate that below the sea bottom lava outcropped from west of stake 5 km,solid sedimentary rocks exposed in the middle section while a sequence of unconsolidated sediments existing in other areas.The burial depth of basement are about 1600 m in the western section and over 2000 m from east of stake 60 km.The Coastal Fault Zone on this inversion section show up as a southeast-dipping extensional normal-fault system and its direction is about 50 km southeast of Jinjiang.

关 键 词：滨海断裂带 回折波 最大速度梯度法 地震层析成像 

分 类 号：P315[天文地球—地震学] P541[天文地球—固体地球物理学]