中国东南部地区背景地震重新定位及隐伏活动构造初步研究

doi:10.3969/j.issn.0253-4967.2017.01.005

摘要/Abstract

摘要：

中国东南部地区或分布崇山峻岭，或为新生代盆地覆盖，因而活动断裂的发现与定位极为困难。沿断裂的地震活动可以成为断裂现今活动的直接证据，但需要地震的精确定位。文中通过精定位背景地震活动性，初步分析了区域构造活动与背景地震活动的关系，解译了研究区存在的隐伏活动断裂。利用双差地震定位法对中国东南部地区大致22°~35°N，106°~122°E范围内1990-2014年发生的背景地震开展了重新定位工作，重新定位了51000多个小震的震源参数。重新定位的背景地震活动表现出与区域构造活动相一致的分布特征，具有分区活动性，不同构造区出现不同的分布样式。现今活动较弱的构造区，地震活动分布离散或稀疏，没有指示出隐伏活动断裂的存在。在现今活动较强的构造区，地震活动明显集中成线性条带状，线性条带的展布样式和方向与区域构造格局和主要断裂走向一致。以线性条带分布的背景地震活动性揭示出的隐伏活动断裂主要分布在东南沿海一带、桂西北地区、四川盆地东南缘以及霍山一带，多数为以往研究所未发现的断裂。重新定位地震在不同构造区的震源深度分布差异明显，在块体中部区域震源深度最浅，主要分布在0~15km，表明脆性变形主要发生在上地壳，中下地壳为半塑性、塑性变形状态；在东南沿海一带，有下地壳地震发生。震源深度最深的区域为四川盆地的东南缘一带，有地震震源深度分布在40~44km，反映了地壳厚度大且下地壳为脆性变形特征，与较低的大地热流值和较硬的流变强度相一致。

关键词: 地震重新定位, 背景地震活动性, 地壳变形特征, 隐伏活动断裂, 中国东南部地区

Abstract:

Most of the regions in southeastern China are covered by thick Cenozoic sediments, or are the mountainous areas, so it is difficult to find and locate the active faults using the conventional geologic methods. The precisely relocated background seismicity in the seismically active region can be used to identify the buried active structure. In this paper, we investigated the relationship between regional tectonics and background seismicity, and interpreted the possible buried active faults in southeastern China using the relocated background seismicity. We relocated the background seismicity occurring in the region from 106°E to 122°E and from 22°N to 35°N between 1990 and 2014 using the doubble difference earthquake location algorithm. More than 51000 small earthquakes were relocated. In general, the relocated background seismicity corresponds well to the tectonics, showing the zonation features with typical seismicity pattern in each tectonic regime. It is observed that in the weakly active tectonic regime, the seismicity distributes dispersely or even scarcely, while in the strongly active tectonic region, the seismicity is highly clustered and organized to lineation pattern showing the same direction as the strike of the dominating fault zone. We interpreted the buried active faults using the lineation of seismicity. The inferred active faults are observed in the southeast coast region, the northwest Guangxi Province, the southeast boundary region of the Sichian Basin, and around the Huoshan Fault, many of which were not found by previous studies. The relocated hypocentral depth varies greatly in southeastern China. The shallowest earthquakes between 0 and 15km mainly distribute in the central region, indicating that the brittle deformation process only occurred in the upper crust, while the middle and lower crust are to be half-ductile and ductile deformation. There are earthquakes occurred in lower crust in the southeast coast region. The maximum depths distribute in the southeast boundary region of the Sichuan Basin, some are greater than 40km, indicating that the crust depth is larger than other places and the lower crust still sustains brittle deformation, which corresponds to the lower geothermal value and high crustal strength.

Key words: earthquake relocation, background seismicity, crustal deformation characteristics, buried active fault, southeastern China

中图分类号:

P315.2

朱艾斓, 徐锡伟, 任烨, 孙冬军, 王鹏, 于海英, 宋秀青, 刘芳. 中国东南部地区背景地震重新定位及隐伏活动构造初步研究[J]. 地震地质, 2017, 39(1): 67-80.

ZHU Ai-lan, XU Xi-wei, REN Ye, SUN Dong-jun, WANG Peng, YU Hai-ying, SONG Xiu-qing, LIU Fang. RELOCATION OF THE BACKGROUND SEISMICITY AND INVESTIGATION ON THE BURIED ACTIVE FAULTS IN SOUTHEASTERN CHINA[J]. SEISMOLOGY AND GEOLOGY, 2017, 39(1): 67-80.

参考文献

安美建, 石耀霖. 2007. 中国大陆地壳和上地幔三维温度场［J］. 中国科学 (D辑), 37(6): 736-745.
AN Mei-jian, SHI Yao-lin. 2007. Three-dimensional thermal structure of the Chinese continental crust and upper mantle［J］. Science in China(Ser D), 50(10): 1441-1451.
白志明, 王椿镛. 2006. 下扬子地壳P波速度结构: 符离集-奉贤地震测深剖面再解释［J］. 科学通报, 51(21): 2534-2541.
BAI Zhi-ming, WANG Chun-yong. 2006. Crustal P-wave velocity structure in Lower Yangtze region: Reinterpretation of Fuliji-Fengxian deep seismic sounding profile［J］. Chinese Science Bulletin, 51(19): 2391-2400.
蔡学林, 朱介寿, 曹家敏, 等. 2007. 中国大陆及邻区岩石圈地壳三维结构与动力学型式［J］. 中国地质, 34(4): 543-557.
CAI Xue-lin, ZHU Jie-shou, CAO Jia-min,et al. 2007. 3D structure and dynamic types of the lithospheric crust in continental China and its adjacent regions［J］. Geology in China, 34(4): 543-557(in Chinese).
邓起东, 卢造勋, 杨主恩. 2007. 城市活动断层探测和断层活动性评价问题［J］. 地震地质, 29(2): 189-200.
DENG Qi-dong, LU Zao-xun, YANG Zhu-en. 2007. Remarks on urban active faults exploration and associated activity assessment［J］. Seismology and Geology, 29(2): 189-200(in Chinese).
邓起东, 闻学泽. 2008. 活动构造研究: 历史、进展与建议［J］. 地震地质, 30(1): 1-30.
DENG Qi-dong, WEN Xue-ze. 2008. A review on the research of active tectonics: History, progress and suggestions［J］. Seismology and Geology, 30(1): 1-30(in Chinese).
邓起东, 徐锡伟, 张先康, 等. 2003. 城市活动断裂探测的方法和技术［J］. 地学前缘, 10(1): 93-104.
DENG Qi-dong, XU Xi-wei, ZHANG Xian-kang,et al. 2003. Methods and techniques for surveying and prospecting active faults in urban areas［J］. Earth Science Frontiers, 10(1): 93-104(in Chinese).
邓起东, 张培震, 冉勇康, 等. 2002. 中国活动构造基本特征［J］. 中国科学(D辑), 32(12): 1020-1030.
DENG Qi-dong, ZHANG Pei-zhen, RAN Yong-kang,et al. 2003. Basic characteristics of active tectonics of China［J］. Science in China(Ser D), 46(4): 356-372.
邓阳凡, 李守林, 范蔚茗, 等. 2011. 深地震测深揭示的华南地区地壳结构及其动力学意义［J］. 地球物理学报, 54(10): 2560-2574.
DENG Yang-fan, LI Shou-lin, FAN Wei-ming,et al. 2011. Crustal structure beneath South China revealed by deep seismic soundings and its dynamics implications［J］. Chinese Journal of Geophysics, 54(10): 2560-2574(in Chinese).
国家测震台网数据备份中心. 2007. 国家测震台网地震波形数据［DB/OL］. 中国地震局地球物理研究所, doi:10.11998/SeisDmc/SN.
Data Management Centre of National Seismic Network. 2007. Waveform data of China National Seismic Network ［DB/OL］. Institute of Geophysics, China Earthquake Administration, doi:10.11998/SeisDmc/SN.
国家地震局震害防御司. 1995. 中国历史强震目录［Z］. 北京: 地震出版社.
Department of Earthquake Disaster Prevention of the State Seismological Bureau.1995. The catalogue of Chinese historical strong earthquakes ［Z］. Seismological Press, Beijing (in Chinese).
中国地震局震害防御司. 1999. 中国近代地震目录［Z］. 北京: 中国科学技术出版社.
Department of Earthquake Disaster Prevention of the China Earthquake Administration. 1999. The catalogue of Chinese modern earthquakes ［Z］. China Science and Technology Press, Beijing (in Chinese).
火恩杰, 章振铨, 姚保华, 等. 2007. 上海市活断层探测与地震危险性评价［R］. 上海: 上海市地震局.
HUO En-jie, ZHANG Zhen-quan, YAO Bao-hua,et al. 2007. Report of active fault exploration and seismic hazard estimation for Shanghai Municipality［R］. Earthquake Administration of Shanghai, Shanghai (in Chinese).
江娃利. 2006. 有关华北平原强震发震构造问题的讨论［J］. 中国地震, 22(2): 135-141.
JIANG Wa-li. 2006. Discussion on problems for seismo-tectonics of strong earthquakes in the North China plain［J］. Earthquake Research in China, 22(2): 135-141(in Chinese).
李传友, 汪一鹏, 王志才. 2007. 中国东部城市地区隐伏断裂上断点与最新活动时代关系的初步分析: 以邢台、唐山地震区为例［J］. 地震地质, 29(2): 431-445.
LI Chuan-you, WANG Yi-peng, WANG Zhi-cai. 2007. Some analyses on the relation between the upper offset point and the latest activity times of buried faults in cities of eastern China: Taking the Xingtai and Tangshan earthquake regions as an example［J］. Seismology and Geology, 29(2): 431-445(in Chinese).
李廷栋. 2010. 中国岩石圈的基本特征［J］. 地学前缘, 17(3): 1-13.
LI Ting-dong. 2010. Principal characteristics of the lithosphere of China［J］. Earth Science Frontiers, 17(3): 1-13(in Chinese).
沈正康, 王敏, 甘卫军, 等. 2003. 中国大陆现今构造应变率场及其动力学成因研究［J］. 地学前缘, 10(S1): 93-100.
SHEN Zheng-kang, WANG Min, GAN Wei-jun,et al. 2003. Contemporary tectonic strain rate field of Chinese continent and its geodynamic implications［J］. Earth Science Frontiers, 10(S1): 93-100(in Chinese).
汪洋, 程素华. 2011. 中国东部岩石圈热状态与流变学强度特征［J］. 大地构造与成矿学, 35(1): 12-23.
WANG Yang, CHENG Su-hua. 2011. Thermal state and rheological strength of the lithosphere beneath the eastern China［J］. Geotectonica et Metallogenia, 35(1): 12-23(in Chinese).
向宏发, 韩竹军, 张晚霞, 等. 2008. 中国东部中强地震发生的地震地质标志初探［J］. 地震地质, 30(1): 202-208.
XIANG Hong-fa, HAN Zhu-jun, ZHANG Wan-xia,et al. 2008. Preliminary study on seismogeologic evidence for moderate earthquakes in East China［J］. Seismology and Geology, 30(1): 202-208(in Chinese).
徐纪人, 赵志新, 石川有三. 2008. 中国大陆地壳应力场与构造运动区域特征研究［J］. 地球物理学报, 51(3): 770-781.
XU Ji-ren, ZHAO Zhi-xin, Yuzo I. 2008. Regional characteristics of crustal stress field and tectonic motions in and around Chinese mainland［J］. Chinese Journal of Geophysics, 51(3): 770-781(in Chinese).
徐明, 朱传庆, 田云涛, 等. 2011. 四川盆地钻孔温度测量及现今地热特征［J］. 地球物理学报, 54(4): 1052-1060.
XU Ming, ZHU Chuan-qing, TIAN Yun-tao,et al. 2011. Borehole temperature logging and characteristics of subsurface temperature in Sichuan Basin［J］. Chinese Journal of Geophysics, 54(4): 1052-1060(in Chinese).
徐锡伟, 吴卫民, 张先康, 等. 2002a. 首都圈地区地壳最新构造变动与地震［M］. 北京: 科学出版社. 1-376.
XU Xi-wei, WU Wei-min, ZHANG Xian-kang,et al. 2002a. The Recent Crust Tectonic Deformation and Earthquake in the Capital Region［M］. Science Press, Beijing. 1-376(in Chinese).
徐锡伟, 于贵华, 马文涛, 等. 2002b. 活断层地震地表破裂 "避让带"宽度确定的依据与方法［J］. 地震地质, 24(4): 470-483.
XU Xi-wei, YU Gui-hua, MA Wen-tao,et al. 2002b. Evidence and methods for determining the safety distance from the potential earthquake surface rupture on active fault［J］. Seismology and Geology, 24(4): 470-483(in Chinese).
徐锡伟, 于贵华, 冉勇康, 等. 2015. 中国城市活动断层概论: 20个城市活动断层探测成果［M］. 北京: 地震出版社.
XU Xi-wei, YU Gui-hua, RAN Yong-kang,et al. 2015. Introduction to Urban Active Faults: Results of Active Faults Exploration in 20 Cities in China［M］. Seismological Press, Beijing(in Chinese).
徐锡伟, 于贵华, 王峰, 等. 2000. 1966年邢台地震群的发震构造模型: 新生断层形成?先存活断层摩擦黏滑?［J］. 中国地震, 16(4): 364-378.
XU Xi-wei, YU Gui-hua, WANG Feng,et al. 2000. Seismogenic model for the 1966 Xingtai earthquakes: Nucleation of new-born fault or stick-slip of pre-existing fault?［J］. Earthquake Research in China, 16(4): 364-378(in Chinese).
杨晓平, 袁洪克, 宋新初, 等. 2011. 浙江宁波育王山山前隐伏断层勘探和新活动时代［J］. 地球科学-中国地质大学学报, 36(6): 967-976.
YANG Xiao-ping, YUAN Hong-ke, SONG Xin-chun,et al. 2011. Exploration of the buried fault in front of Yuwang Mountain and its neomovement's epoch in Ningbo, Zhejiang Province［J］. Earth Science-Journal of China University of Geosciences, 36(6): 967-976(in Chinese).
尹周勋, 赖明惠, 熊绍柏, 等. 1999. 华南连县-博罗-港口地带地壳结构及速度分布的爆炸地震探测结果［J］. 地球物理学报, 42(3): 383-392.
YIN Zhou-xun, LAI Ming-hui, XIONG Shao-bai,et al. 1999. Crustal structure and velocity distribution from deep seismic sounding along the profile of Lianxian-Boluo-Gangkou in South China［J］. Chinese Journal of Geophysics, 42(3): 383-392(in Chinese).
于贵华, 杜克平, 徐锡伟, 等. 2012. 活动构造数据库建设相关问题的研究［J］. 地震地质, 34(4): 713-725. doi: 10.3969/j.issn.0253-4967.2012.04.014.
YU Gui-hua, DU Ke-ping, XU Xi-wei,et al. 2012. Research on active fault database construction related issues［J］. Seismology and Geology, 34(4): 713-725(in Chinese).
袁学诚, 华九如. 2011. 华南岩石圈三维结构［J］. 中国地质, 38(1): 1-19.
YUAN Xue-cheng, HUA Jiu-ru. 2011. 3D Lithospheric structure of South China［J］. Geology in China, 38(1): 1-19(in Chinese).
赵志新, 徐纪人. 2009. 广角反射地震探测得到的中国东部地壳三维P波速度结构［J］. 科学通报, 54(7): 931-937.
ZHAO Zhi-xin, XU Ji-ren. 2009. Three-dimensional crustal velocity structure of P-wave in East China from wide-angle reflection and refraction surveys［J］. Chinese Science Bulletin, 54(8): 1389-1397.
郑圻森, 朱介寿, 宣瑞卿, 等. 2003. 华南地区地壳速度结构分析［J］. 沉积与特提斯地质, 23(4): 9-13.
ZHENG Qi-sen, ZHU Jie-shou, XUAN Rui-qing,et al. 2003. An approach to the crustal velocities in southern China［J］. Sedimentary Geology and Tethyan Geology, 23(4): 9-13(in Chinese).
郑秀芬, 欧阳飚, 张东宁, 等. 2009. "国家数字测震台网数据备份中心"技术系统建设及其对汶川大地震研究的数据支撑［J］. 地球物理学报, 52(5): 1412-1417.
ZHENG Xiu-fen, OUYANG Biao, ZHANG Dong-ning,et al. 2009. Technical system construction of Data Backup Centre for China Seismograph Network and the data support to researches on the Wenchuan earthquake［J］. Chinese Journal of Geophysics, 52(5): 1412-1417(in Chinese).
Amelung F, King G. 1997. Earthquake scaling laws for creeping and non-creeping faults［J］. Geophysical Research Letters, 24(5): 507-510.
Fuis G S, Scheirer D S, Langenheim V E,et al. 2012. A new perspective on the geometry of the San Andreas Fault in southern California and its relationship to lithospheric structure［J］. Bulletin of the Seismological Society of America, 102(1): 236-251.
Kroll K A, Cochran E S, Richards-Dinger K B,et al. 2013. Aftershocks of the 2010 M_W 7.2 El Mayor-Cucapah earthquake reveal complex faulting in the Yuha Desert, California［J］. Journal of Geophysical Research, 118(12): 6146-6164.
Li L, Chen Q F, Niu F L,et al. 2011. Deep slip rates along the Longmen Shan fault zone estimated from repeating microearthquakes［J］. Journal of Geophysical Research, 116(B9): B09310.
Liu M, Yang Y Q. 2005. Contrasting seismicity between the North China and South China blocks: Kinematics and geodynamics［J］. Geophysical Research Letters, 32(12): L12310.
Nadeau R M, McEvilly T V. 1999. Fault slip rates at depth from recurrence intervals of repeating microearthquakes［J］. Science, 285(5428): 718-721.
Shaw J H, Shearer P M. 1999. An elusive blind-thrust fault beneath Metropolitan Los Angeles［J］. Science, 283(5407): 1516-1518.
Shearer P M. 1997. Improving local earthquake locations using the L1 norm and waveform cross correlation: Application to the Whittier Narrows, California, aftershock sequence［J］. Journal of Geophysical Research, 102(B4): 8269-8283.
Waldhauser F, Ellsworth W L. 2000. A double-difference earthquake location algorithm: Method and application to the northern Hayward Fault, California［J］. Bulletin of the Seismological Society of America, 90(6): 1353-1368.
Wolfe C J, Okubo P G, Shearer P M. 2003. Mantle fault zone beneath Kilauea volcano, Hawaii［J］. Science, 300(5618): 478-480.

[1]	李建华, 郝书俭, 胡玉台. 关于NWW向昌平-丰南隐伏断裂的新证据和分析[J]. 地震地质, 1999, 21(2): 178-184.
[2]	林元武, 翟盛华, 范树全, 孔令昌. 华北隐伏活动断裂H₂异常特征及其异常机制研究[J]. 地震地质, 1994, 16(3): 264-268.
[3]	汪素云. 地震重新定位在核电厂厂址地震安全性评价中的重要性[J]. 地震地质, 1993, 15(4): 389-394.