地球物理学进展 ›› 2018, Vol. 33 ›› Issue (3): 957-968.doi: 10.6038/pg2018BB0348

• 固体地球物理及空间物理学(大气、行星、地球动力学、重磁电及地震学、地热学) • 上一篇    下一篇

华北盆地边缘及邻区地壳S波速度结构及其地震孕育机制

曲中党1,2,3,4,5,6(),张训华2,5,贺日政3,*(),吴志强4,张洪双6,吴蔚6   

  1. 1. 中国海洋大学,海洋地球科学学院,山东青岛 266100
    2. 青岛海洋科学与技术国家实验室海洋矿产资源评价与探测技术功能实验室,山东青岛 266000
    3. 自然资源部深地动力学重点实验室,中国地质科学院,北京 100037
    4. 青岛海洋地质研究所,山东青岛 266071
    5. 南京地质调查中心,南京 210016
    6. 中国地质科学院地质研究所,北京 100037
  • 收稿日期:2017-08-04 修回日期:2018-04-22 出版日期:2018-08-22 发布日期:2018-08-27
  • 通讯作者: 贺日政 E-mail:quzhongdang@163.com;herizheng@cags.ac.cn
  • 作者简介:第一作者简介 曲中党,男,1991年生,博士研究生,海洋地球物理学专业,主要从事地震学研究. (E-mail:quzhongdang@163.com)
  • 基金资助:
    国家自然基金项目(41761134094, 41274095, 41430213, 41590863);国土资源部公益行业基金项目(201011044);国家重点基础研究发展计划项目(2013CB429701,2016YFC0600301);中国地质调查局项目(DD20189132)

S wave velocity structure of the crust and the mechanisms of earthquake occurrence in the North China Basin and its adjacent areas

QU Zhong-dang1,2,3,4,5,6(),ZHANG Xun-hua2,5,HE Ri-zheng3,*(),WU Zhi-qiang4,ZHANG Hong-shuang6,WU Wei6   

  1. 1. College of Marine Geosciences, Ocean University of China, Shandong Qingdao 266100, China
    2. Function Laboratory for Marine Mineral Resource Geology and Exploration, Qingdao National Oceanography Laboratory, Shandong Qingdao 266000, China
    3. Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
    4. Qingdao Institute of Marine Geology, Shandong Qingdao 266071, China 5. Nanjing Center, China Geological Survey, Nanjing 210016, China
    5. Nanjing Center, China Geological Survey, Nanjing 210016, China
    6. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
  • Received:2017-08-04 Revised:2018-04-22 Online:2018-08-22 Published:2018-08-27
  • Contact: Ri-zheng HE E-mail:quzhongdang@163.com;herizheng@cags.ac.cn

摘要:

利用分布在华北盆地及其周边(113°E—121°E,34°N—41°N)72个固定地震台站记录到的2009年和2010年远震地震波形记录,提取多频段P波接收函数,反演了台站下方的S波速度结构,并结合该区域1970—2016年的地震目录分析了反演结果.华北盆地周缘及邻区中下地壳普遍存在低速异常,首都圈地区Moho深度约在33 km左右,台站下方在4~10 km的深度范围内一般都存在2~5 km厚的高速层,紧随高速层之下又出现了2~6 km厚的相对低速层;在太行山隆起向华北盆地的过渡区,地壳结构较为复杂,Moho面深度变化较大,自西向东深度变浅,且太行山隆起区内明显存在壳内低速层,而接近华北盆地处的地壳内存在轻微的速度扰动异常(即低速层);鲁西隆起地区Moho深度在31~34 km之间,在大地热流高值区地壳高低速异常明显.基于华北盆地周缘地区地震在地壳高低速层均有分布,而分布在低速层内的地震事件相对较多, 比较符合曾融生等(1991)提出的“双层破裂震源模型”,即地幔热物质上侵导致了中下地壳的低速软弱层形成,并在软弱层处产生了附加的水平剪切力,进而其破裂诱发地震,同时将部分应力传递给上覆高速硬包体,为高速异常体内地震的触发积累能量.华北盆地周缘低速异常体的分布是该区域地震频发的重要诱因.

关键词: 华北盆地, 接收函数反演, 地壳S波速度, 壳内低速层, 震源深度

Abstract:

We collected the teleseismic earthquakes data of 72 permanent seismic stations recorded in 2009 and 2010, and the history earthquake catalogue form 1970 to 2016 in North China Basin and adjacent area (113°E—121°E, 34°N—41°N). We obtain the S wave velocity structure beneath the stations by receiver function inversion, and analyze the relation between earthquakes and the S wave velocity structure. The results show that the North China Basin and its adjacent areas generally exist low velocity anomalies in the middle and lower crust. The depth of Moho in capital area are about 33 km, beneath the stations in the depth range of 4~10 km generally exist a 2~5 km thick high velocity layer and followed by a 2~6 km thick relatively low velocity layer; The transition zone of Taihang Mountain uplift to North China Basin have the complex crustal structure. The depth of Moho varies fast from west to east. The obvious vary trend of Moho depth from west to east is become shallower. There are obvious low velocity in the crust of the Taihang Mountain uplift area, which become the slight disturbance abnormal velocity (low velocity layer) when close to the North China Basin; The Moho depth of Luxi uplift area range from 31 km to 34 km. There are obvious low velocity layer in the high heat flow area. Based on the phenomena of earthquakes occurs in both the high and low velocity layer in the crust of surrounding areas of North China Basin, we think, “the two-level seismic source model”, proposed by Zeng et al (1991), is more suitable with the observed results. The hot materials extended from uppermost mantle to the middle crust formed the low velocity layer and the horizontal tectonic stress field which induced the earthquake. After the earthquake rupture in low velocity layer, the stress will transfer to the overlying high velocity layer. When the high velocity layer accumulated enough energy, the strong earthquake will occur in high velocity anomaly area. The distribution of low velocity anomalies in the periphery of the North China basin is an important trigger factor of frequent earthquakes. It is important to study the fine structure of the crust and investigate the distribution and physical properties of low velocity anomalies for the long and medium earthquake prediction.

Key words: North China Basin, receiver function inversion, crustal S wave velocity, intra-crustal low velocity layer, focal depth

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