利用气枪地震资料对福建及台湾海峡南部地壳三维P波速度结构研究  

3D P-wave velocity structure of crust in Fujian and the southern Taiwan Strait derived from air-gun seismic data

作　　者：金震 李山有[1] 蔡辉腾[2] 李培[2] 李海艳 徐嘉隽[2] JIN Zhen;LI ShanYou;CAI HuiTeng;LI Pei;LI HaiYan;XU JiaJun(Institute of Engineering Mechanics, China Earthquake Administration, Key Laboratory of Earthquake Engineering and Engineering Vibration, China Earthquake Administration, Harbin 150000, China;Earthquake Administration of Fujian Province ,Fuzhou 350000, China)

机构地区：[1]中国地震局工程力学研究所和中国地震局地震工程与工程振动重点实验室,哈尔滨150000 [2]福建省地震局,福州350000

出　　处：《地球物理学报》2018年第7期2776-2787,共12页Chinese Journal of Geophysics

基　　金：地震行业科研专项项目(2015419015);国家自然科学基金项目(41474071);地震科技星火计划项目(XH1015)资助

摘　　要：根据福建及台湾海峡南部海陆联测试验记录到的Pg和Pm震相走时数据,利用速度与界面联合成像方法构建地壳三维P波速度结构,揭示了该区地壳深部构造特征.结果表明:福建和台湾海峡海陆过渡带以及海峡南部地壳速度结构存在明显的不均匀性,滨海断裂两侧速度结构复杂,随深度呈现明显的分段特征,其上地壳海陆过渡带呈高速特性,台湾海峡呈低速特性;下地壳海陆过渡带呈低速特性,台湾海峡呈高速特性;研究区莫霍面的深度约为28~33km,存在较明显差异,闽粤交接部位存在明显的地壳厚度减薄,莫霍面深度接近28km,这与正常型华南活动地块与减薄型南海活动地块交汇致使地壳厚度减薄有关,体现了活动块体边界构造特征.历史大震主要发生在高低速异常过渡带且有深大断裂穿过的区域,现今中小震主要分布于闽粤海陆过渡带,这一特征可能与此地广泛发育的断层和华南与南海活动地块相互作用有关.Based on the travel time of Pg and Pm recorded by the sea-land crustal deep exploration in Fujian and the southern Taiwan Strait,the 3D crustal velocity structure is studied by the joint tomography of velocity and interface.The results show that there is obvious heterogeneity in the crustal velocity structure in the study area.On either side of the Binhai fault,the upper crust of the sea-land transitional zone is characterized by high velocity,while by low velocity in the Taiwan Strait.In the lower crust,the sea-land transitional zone is of low velocity,while high velocity in the Taiwan Strait.The Moho depth in the study area is 28~33 km.The junction of Fujian and Guangdong provinces has obvious thin crust,where the Moho depth is close to 28 km,which may be related to the thinning of the crust,associated with the intersection of normal crust in the active South China block and thinned crust in the South China Sea block,representing the tectonic characteristics of active block boundaries.The great historical earthquakes occurred mainly in the transition zone between high and low velocity anomalies where deep faults run through,and the small-and medium-size earthquakes are mainly distributed in the sea-land transition zone of Fujian and Guangdong provinces.We suggest this feature may be related to the widespread faults and the interaction between active South China and South China Sea blocks.

关 键 词：海陆联测 地震层析成像 地壳P波速度 莫霍面深度 

分 类 号：P315[天文地球—地震学] P313[天文地球—固体地球物理学]