摘要
辽宁海城地震区处于郯庐断裂带北延段的下辽河盆地和辽东隆起交界,区内地震活动活跃,历年被划定为地震危险区.本文基于该地区最新架设的23个宽频带流动地震台和营口固定台观测的近一年远震波形,利用远震P波接收函数H-κ叠加方法和共中心点(CCP)叠加成像获得了研究区西侧下辽河盆地和东侧辽东隆起的三维高分辨率地壳结构,结果显示:海城地震区地壳厚度在24.2~33.3 km之间,地壳泊松比在0.24~0.34之间;西侧下辽河盆地区地壳较薄,最薄处仅24.2 km,而东侧辽东隆起区地壳总体较厚,最厚处达33.3 km.区内盆地与山地构造区莫霍面过渡平稳,但在下辽河盆地区存在2处上地幔凸起,与重力数据和地震反射剖面结果一致.辽东隆起区的泊松比普遍低于0.26,且无明显剩余地形异常.下辽河盆地的泊松比均值大于0.3,剩余地形有明显的正异常,最大幅度达1.18 km,暗示盆地区在过去区域拉张应力作用下发生幔源物质上涌并导致地壳减薄.我们推断区域构造应力、地幔热物质上涌可能是下辽河盆地构造东缘和辽东隆起块体内发生频繁地震活动的重要力源条件.
The Haicheng seismic zone,crossing from the Xialiaohe Basin to Liaodong Uplift,is located in northern part of the Tanlu fault system.It has been delimited as high-risk seismic area in Chinese continent due to its intense seismicity.In this article,we construct high-resolution 3D crustal structure of the Haicheng seismic zone using the broadband seismic data from 23 newly distributed dense mobile array and the fixed Yingkou station in the area.Specifically,the H-κmethod and Common Converse Point(CCP)stack imaging are carried out using teleseismic P-wave receiver functions.Our results show that the regional crustal thickness is between 24.2~33.3 km with the crustal Possion′s ratio ranging between 0.24~0.34.The Xialiaohe Basin on the west side of the area has a thin crust with a thinnest thickness of 24.2 km while the Liaodong Uplift on the east side is thicker with a maximum thickness of 33.3 km.The Moho has a smooth variation from the Xialiaohe Basin to the Liaodong Uplift;notably,two mantle uplifts are observed beneath the Xialiaohe Basin,consistent with gravity data and seismic reflection profiles.The Liaodong Uplift generally exhibits a Poisson′s ratio lower than 0.26 and no significant residual topographic anomalies.In contrast,the Lower Liaohe Basin features an average Poisson′s ratio exceeding 0.3,with distinct positive residual topography anomalies reaching a maximum amplitude of 1.18 km,which suggest that,due to the tensile stress,there may be local melting or upwelling of mantle-derived material,resulting in crustal thinning.The regional tectonic stress and the upwelling of the mantle material may jointly affect the seismic activities at the eastern edge of the Xialiaohe Basin and inside the Liaodong Uplift.
作者
邵媛媛
白兰淑
刘嘉栋
孙庆山
张瑞青
王亮
焦明若
贾丽华
吴庆举
SHAO YuanYuan;BAI LanShu;LIU JiaDong;SUN QingShan;ZHANG RuiQing;WANG Liang;JIAO MingRuo;JIA LiHua;WU QingJu(Liaoning Earthquake Agency,Shenyang 110034,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Key Laboratory of Earthquake Source Physics,China Earthquake Administration,Beijing 100081,China)
出处
《地球物理学报》
北大核心
2025年第2期517-530,共14页
Chinese Journal of Geophysics
基金
中国地震局地球物理研究所基本科研业务费专项(DQJB21B34)
辽宁省地震局青年基金项目(2022036)
国家自然科学基金项目(41874073)共同资助
关键词
海城地震区
接收函数
密集台阵
地壳厚度
泊松比
Haicheng seismic zone
Receiver function
Dense array
Crustal thickness
Poisson′s ratio
