摘要
海域活动断裂的发现和证实及其灾害风险评估,一直以来是困扰全球海洋地质界的难题。现有案例聚焦于俯冲带地区,往往基于间接方法判断断裂活动性和海底古地震事件,鲜有研究可直接证实海底活动断裂的存在,特别是在靠近陆地的陆内变形区域。我国华南沿海的特大型城市群——粤港澳大湾区紧靠南海,可能面临着来自海域活动断裂带来的地质灾害链威胁。本研究综合应用GPS、多道地震、单道地震和历史地震数据,发现南海北部存在两条大型活动断裂带:滨海断裂带和陆坡断裂带。GPS速度场数据表明,两条断裂均具有右旋走滑性质,其中陆坡断裂带整体运动速率约为3.0 mm/yr,滨海断裂带运动速率为0.8~1.2 mm/yr。多道和单道地震结果表明,滨海断裂带在剖面上表现为上陡下缓“铲形”结构,断错最新地层年龄约1万年,是一条未切穿海底的隐伏活动断裂;陆坡断裂带平面上呈右行左阶雁列式排列,剖面上表现为近直立的特征,在海底形成~10m高的断层陡坎,是一条切穿海底的活动断裂。南海北部的两条活动断裂带,被证实为海底地震、海底滑坡和海啸的主要致灾源,对其开展详细研究为华南沿海重要城市未来的防震减灾提供直接的科学支撑。
Detecting and verifying marine active faults has been a challenging puzzle in global marine geology.The present cases focus on indirectly characterizing active faults in offshore subduction zones,while few have directly identified active faults in coastal region.There are many mega cities along the coastal areas of South China,such as the Guangdong-Hong Kong-Macao Greater Bay Area,which may be exposed to the threat of marine geological hazards caused by active faults.In this study,using GPS,multi-and single-channel seismic,and historical earthquake data,we report two active fault zones in the northern South China Sea:the Littoral Fault Zone(LFZ)and Slope Fault Zone(SFZ).The GPS displacement velocity field results show that both fault zones have the dextral strike-slip characteristics,with the dextral rate of the LFZ being 0.8-1.2 mm/yr,and the dextral rate of the SFZ being about 3.0 mm/yr.The results of the single-channel and multi-channel seismic data show that the LFZ is a listric normal fault,which cuts the sedimentary layer dated to approximately 10,000 years old,and we confirm that the LFZ is a blind active fault under the seafloor.The SFZ cuts through the seafloor,it is a nearly vertical normal fault at depth,and its strike morphology is similar to those of strike-slip control features,which can have both strike-slip characteristics.This discovery clarifies the primary source of marine geological hazards in the northern South China Sea,and providing fundamental data to support earthquake prevention and disaster mitigation efforts in South China’s key coastal cities.
作者
李志刚
张培震
王伟涛
代向明
曾凡长
李琳琳
王大伟
杨小强
郝明
惠格格
梁浩
闫永刚
张逸鹏
田晴映
许斌斌
孙文
LI Zhigang;ZHANG Peizhen;WANG Weitao;DAI Xiangming;ZENG Fanchang;LI Linlin;WANG Dawei;YANG Xiaoqiang;HAO Ming;HUI Gege;LIANG Hao;YAN Yonggang;ZHANG Yipeng;TIAN Qingying;XU Binbin;SUN Wen(Guangdong Provincial Key Lab of Geodynamics and Geohazards/School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,Guangdong,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,Guangdong,China;Institute of Deep-sea Science and Engineering,Chinese Academy of Sciences,Sanya 572000,Hainan,China;The Second Monitoring and Application Center,China Earthquake Administration,Xi’an 710054,Shaanxi,China;Guangdong Earthquake Agency,Guangzhou 510070,Guangdong,China)
出处
《大地构造与成矿学》
北大核心
2025年第5期1027-1035,共9页
Geotectonica et Metallogenia
基金
国家重点研发计划项目(2023YFC3008600)
国家自然科学基金项目(42172233)联合资助。
关键词
海域活动断裂
粤港澳大湾区
滨海断裂带
陆坡断裂带
海洋地质灾害
marine active fault
Guangdong-Hong Kong-Macao Greater Bay Area
Littoral Fault Zone
Slope Fault Zone
marine geological hazard
