1918年南澳地震海啸影响模拟及其警示  

Tsunami simulation of the 1918 Nan’ao earthquake and its implication

作　　者：李琳琳 李发渟 邱强 李志刚 张冬丽 惠格格 LI Linlin;LI Fating;QIU Qiang;LI Zhigang;ZHANG Dongli;HUI Gege(School of Earth Science and Engineering,Sun Yat-sen University,Guangzhou 510275,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,China;South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China)

机构地区：[1]中山大学地球科学与工程学院,广东广州510275 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519082 [3]中国科学院南海海洋研究所,广东广州510301

出　　处：《中山大学学报（自然科学版）（中英文）》2022年第1期27-38,共12页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：南方海洋科学与工程广东省实验室(珠海)创新团队建设项目(311021002);广东省引进人才创新创业团队-环南海地质过程与灾害创新团队项目(2016ZT06N331);国家自然科学基金(41976197,41774049,42076059);中山大学中央高校基本科研业务费(2021qntd23)。

摘　　要：1918年2月13日发生华南沿海南澳岛附近的M;7.5级地震是南海北部少数几个伴有海啸发生的地震之一。历史文献中明确记载了地震发生后在广东和福建沿海出现的一些海啸现象。本研究基于历史文献资料、前人震后调查和对该地震发生区域最新的地球物理探测资料,约束1918年地震参数(震中、破裂范围、断层几何等),通过对几组地震参数详细的海啸模拟,研究该地震事件引发的海啸影响及其特征。模拟结果表明,该地震事件引发的海啸向西可波及至珠江口海域的澳门、珠海,东到福建泉州,影响了直线距离接近800 km的华南沿海,距离震源最近的南澳岛南部和东部受海啸影响最大,青澳湾波高可达3~4 m,其次是福建省东山县(2~3 m)和广东省汕头一带(约1 m)。海啸正波在半小时后即可传播到南澳岛和汕头沿海,到达泉州和香港、澳门沿海的时间分别为3 h和4~5 h。通过对海啸波传播过程、波高分布和典型站点海啸波时序的波谱分析,我们指出滨海断裂带地震触发的海啸具有两个特别需要关注的危险性特征:1)海啸波在华南沿海陆架区域的超长周期振荡,南海北部宽阔的陆架和滨海断裂带与海岸线近乎平行的走向极其有效地将海啸波"捕获"在陆架区域,可产生长达48 h以上的超长时间振荡;2)由海水急剧涨落及超长时间振荡引发的海啸强流会对港口、码头、海产养殖等基础设施密集的华南沿海区域造成严重影响。同时,我们对1918年地震关键参数的敏感性分析也表明海啸的规模和影响范围受控于地震类型和断层几何,目前我们对滨海断裂带精细几何结构和活动性的认识严重不足,亟需开展滨海断裂带海底精细几何结构的探测和活动习性研究,为评价南海北部潜在强震和海啸风险提供科学依据。The 1918 M_(w)7.5 Nan’ao earthquake is one of the few events which are associated with a tsunami in the coastal region of South China.Historical records provide clear evidence of tsunami phenomena along the coasts of Guangdong and Fujian.Based on the constraint of historical records,postearthquake survey,and the most updated geophysical data,we propose several synthetic earthquake scenarios with different fault geometries and investigate the corresponding tsunami hydrodynamics in detail.Our numerical modelling results suggest that the tsunami generated by this event may have affected a large portion of coastline ranging from Macao to Quanzhou in South China.The most impacted region is the southern and eastern coast of Nan’ao island with the maximum tsunami wave height of 3-4 m in Qing’ao Bay.Followed by the coast of Dongshan County in Fujian(2-3 m),and Shantou in Guangdong(~1 m).The first positive tsunami wave arrives in Nan’ao and Shantou in half an hour and reaches Quanzhou,Hong Kong,and Macao in 3 hours,4 hours and 5 hours,respectively.Based on the tsunami propagation process,distributions of tsunami wave height,and the analysis of tsunami waveforms in representative locations,we point out that the tsunami generated by earthquakes along the littoral fault possesses two unique features which may cause substantial damage in the future:1)the long tsunami duration(longer than 48 hours)due to shelf resonance and edge wave trapped in the very broad continental shelf of northern South China Sea;2)strong tsunami currents induced by rapid change of sea level will pose a significant threat to coastal infrastructures,e.g.ports,wharves,and aquaculture farms in southern China.Our sensitivity tests on earthquake parameters suggest that the tsunamigenic capacity is strongly affected by the source mechanism and fault geometries.Detailed marine geophysical surveys are required to better understand the geometrical characteristics and seismogenic behavior of the littoral fault.Such geophysical data provides the scientifi

关 键 词：海域地震 海啸 陆架振荡 滨海断裂带 

分 类 号：P731.25[天文地球—海洋科学]