台湾海峡7.3级地震对厦门的影响

本文根据宏观调查资料，就１９９４年９月１６日台湾海峡发生的７．３级地震对厦门市的影响进行了综述和初步分析。文章提出，经济特区和沿海开发区的城市建设应该重视抗震设防。通过这次地震中广东、福建部分地区造成重大人员伤亡事故，说明了加强地震科普宣传教育，提高全社会防震减灾意识的重要性。     

台湾海峡地震余震及汕头市地基震害初步预测

根据灰色系统的一阶灾变模型，对台湾海峡７．３级地震的ＭＬ≥５．０级余震进行了预测，给出了未来可能的发震时间；根据汕头市国际大酒店地下室记录的这次地震的地面加速度时程，反演计算得到了基岩加速度时程，据此进行了地震反应分析，并对地基震害作了分区。     

台湾东地震带地震活动特征及与大陆地震的关系

本文研究了台湾东地震带地震活动的特征及其与中国大陆地震的关系，发现二者具有时间上的同步性和某些动力学特征的联系，既为判定大陆地震趋势提供了参考依据，也为可能统一研究中国大陆和台湾省的地震趋势提供了有价值的线索。     

台湾海峡7.3级地震建筑物震害分析与损失评估

对台湾海峡７．３级地震广东境内建筑物的地震破坏进行了调查，对地震损失进行了总体评估，并根据当地的工程地质情况，建筑物的结构，用材和施工特点等，分析了各种地震破坏形态和破坏规律，为今后的建筑抗震设防提出了有闪斩建议。     

台湾海峡的活动断裂与地震活动

根据地质、地貌、地球物理资料以及晚第四纪地层的分析对比，探讨了台湾海峡ＮＥ、ＮＷ向断裂的活动性及其与地震的关系。研究表明，以晚更新世晚期以来，上述断裂具有明显的活动性，海峡中５级以上地震大多发生在这些断裂附近或其交汇处。     

闽粤海外历史地震与台湾海峡现今强震活动图像

闽粤两省强烈地震多发生在沿海地区,且福建南日岛至广东南澳一线的泉州－汕头地震带地震活动尤为突出。历史上东南沿海地震带曾发生过４次７级以上大地震,而其中３次都发生在泉－汕段海域,继华南地区本世纪著名的１９１８年广东南澳７．３级地震后,１９９４年９月１６日台湾海峡南部又发生７．３级强震,这在经济发达,人口稠密的闽粤沿海地区引起了极大关注。本文通过历史强震活动资料,分析闽粤沿海与台湾海峡强震在时间进程,     

1994年9月16日台湾海峡7.3级地震前的地震活动异常

应用“八五”地震攻关成果及相关软件,对１９９４年９月１６日台湾海峡７．３级地震前震中周围中小地震活动性参量的计算和分析表明,震前震中及邻区地震活动明显增强,累计频度和应变释放发生突变,从１９９１年起出现孕震空区,多项地震活动参量的中短期时空异常显著。     

2018年台湾海峡6.2级地震前地震活动及应力状态研究

通过对2018年台湾海峡6.2级地震震中及邻区地震活动、小震震源机制解、地震视应力等资料进行综合分析, 研究了6.2级地震前区域地震活动及应力状态特征, 结合大陆和台湾岛GPS测量资料的分析, 探讨岛陆两地相对运动对区域应力场等的影响.结果表明: (1)地震前5年起上述区域地震活动明显由弱转强, 中小地震及震群活动由海域逐步向粤闽赣湘交界广泛扩散, 表明地震活动增强可能是较大范围应力场增强所致; (2)震源机制和应力场的分析表明, 区域应力场呈现拉张(震前15年)-挤压(震前5年)-拉张(震前半年)的演化特征; 地震视应力计算结果同样显示震前5年开始区域应力水平快速大幅上升并持续至临震前半年转为下降; (3) GPS基线长期观测表明台湾岛相对大陆存在年度"分离-相聚"交替运动, 6.2级地震前两岸经历了"分离-相聚-分离"2次明显的倒转运动, 运动方式倒转时间与应力场及地震活动变化存在准同步性.分析认为台湾海峡及粤闽赣湘交界等区域应力状态及地震活动可能主要受制于两岸相对运动方式, 台湾岛震前持续近5年朝大陆挤压造成区域应力持续增强可能是导致6.2级地震以剪切破裂方式发生的直接因素.菲律宾海板块位于台湾岛东部的动力触角作用可能是造成台湾岛相对大陆往返运动最主要的驱动力.     

台湾海峡7.3级地震的构造环境

台湾海峡７．３级地震发生在北东东向台湾西南分国地的北缘活动断裂带上，这里的地质构造复杂，断块差异性升降运动强烈，为台湾浅滩隆起与台湾西南断陷分国地的交替地段；也是深部布格重力异常带由北东东转折为北东向的交汇部位，地震等烈度线的轮廓形态大致反映出其发震构造的走向。     

Study on the transverse structures across Taiwan Strait

The mountain ranges are almost NE- or NNE-trending in mainland and Taiwan island across the strait. But a number of correspondent transverse structures across Taiwan Strait have been identified on the basis of morphology, surface structure, deep seismic survey and gravity field etc. Moreover, it is inferred from the square or/and rectangular shape of the isoseist maps of 8 M≥ 6 earthquakes occurring in the western foothill plain of Taiwan that there is an apparent segmentation of the Taiwan Island along the N-S orientation. This has been verified from the GPS’s results of the ground motions measured during the Chi-Chi earthquake in 1999. As a matter of fact, the transverse structures within the Taiwan Island could be correlated with more salient NW- and EW-trending structures in the mainland of Fujian than in Taiwan. The investigation of the transverse structures across Taiwan Strait is conducive to realizing the geology within the strait. Hence, the tectonic sketch map of the strait as well as mainland and island drawn in this context shows NW- and EW-trending structures for the study area.     

1994年台湾海峡7.3级地震发震断层的地震学证据

通过地震学观测资料的分析和研究,并综合其他作者的研究成果,论证了台湾海峡１９９４年７．３级地震发震断层的主破裂面走向应为北西向,地震的发生是由分布于该区域的巴士系构造活动所致。     

台湾海峡深地震探测:HX9测线试验及初步成果

利用海上大容量气枪震源、陆上地震台站(包括流动台站和固定台站)和海底地震仪首次在台湾海峡地区开展了深地震探测试验。试验结果表明,"延平2号"科考船气枪枪阵信号最远传播距离达280km,成功获得了数万道高质量的地震数据,并且识别了不同类型的P波震相。HX9剖面一维地壳结构模型表明,由2个速度间断面产生的Pc及Pm P两组反射波和基底折射波(Pg)所反映的地壳结构构成了该区基本的地壳结构特征,康拉德界面和莫霍界面的深度分别为16.0~17.5、28.0~29.5km。     

Inversion of source process and related studies of the Taiwan Strait earthquake using genetic algorithm

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Undead earthquakes

This short communication deals with the problem of fake earthquakes that keep returning into circulation. The particular events discussed are some very early earthquakes supposed to have occurred in the U.K., which all originate from a single enigmatic 18th century source.     

台湾的地震和地球物理研究

概述自１８９１年以来台湾的地震和地球物理研究的历史发展与当前状况，简要回顾自７０年代以来海峡两岩地震学和地球物理学学术交流的发展。指出，两岸地震和地理物理学界的交流和合作有着广阔的前景，应当而且能够对促进两岸关系的良性发展做出更多的贡献。     

Inversion of source process and related studies of the Taiwan Strait earthquake using genetic algorithm

Applying genetic algorithm to inversion of seismic moment tensor solution and using the data of P waveform from digital network and initial motion directions of P waves of Taiwan network stations, we studied the moment tensor solutions and focal parameters of the earthquake of M=7.3 on 16 September of 1994 in Taiwan Strait and other four quakes of M _L≥5.8 in the near region (21°–26°N, 115°–120°E). Among the five earthquakes, the quake of M=7.3 on September 16, 1994 in Taiwan Strait is the strongest one in the southeastern coast area since Nan’ao earthquake of M=7.3 in 1918. The results show that moment tensor solution of M=7.3 earthquake is mainly double-couple component, and is normal fault whose fault plane is near NW. The strike of the fault plane resembles that of the distributive bands of earthquakes before the main event and fracture pattern shown by aftershocks. The tension stress axis of focal mechanism is about horizontal, near in NE strike, the compressive stress axis is approximately vertical, near in NWW strike. It seems that this quake is controlled by the force of Philippine plate’s pressing Eurasian plate in NW direction. But from the viewpoint of P axis of near vertical and T axis of near horizontal, it is a normal fault of strong tensibility. There are relatively big difference between focal mechanism solution of this quake and those of the four other strong quakes. The complexity of source mechanism solution of these quakes represents the complexity of the process of the strait earthquake sequences. Contribution No. 98A01001, Institute of Geophysics, State Seismological Bureau, China. The subject is supported and helped by Academician Yun-Tai CHEN, Profs. Qing-Yao HONG, Zhen-Xing YAO, Tian-Yu ZHENG, Yao-Lin SHI, Ji-An XU, Bo-Shou HUANG and colleague Mei-Jian AN, Xue-Reng DING, Rui-Feng LIU. De-Chong ZHANG and Ming Li provided the digital data warm-heartedly. Lin-Ying WANG offered us the catalogue of earthquakes in southeastern coastal area in China. Xi-Li WANG and Tong-Xia BAI provided us the issued annual reports data. The authors would like to express their gratitude to all of these people. This paper is sponsored by the National Natural Science Foundation of China and Scientific and Technological Commission of Shantou, Guangdong Province.     

1994年9月16日台湾海峡7.3级地震静态库仑应力变化及断裂危险性初步研究

利用1994年9月16日台湾海峡7.3级地震震源机制解及滑动分布模型的资料,计算了由台湾海峡7.3级地震造成的静态库仑应力变化.对余震的分布进行了研究与分析,从震后余震的分布与应力场的情况及历史上这一地区的震源地分布的角度对库仑应力的变化进行了分析.结果显示,基于滑动分布模型正演的静态库仑应力变化在距震中相对较远的区域与余震分布的一致性较好,约90％的余震发生在库仑应力增加的区域;在震中附近计算出的库仑应力变化比较复杂,与余震的分布序列并不完全一致.在距震中较远的区域,库仑应力变化能比较好的反映余震的分布,而在震中附近库仑应力变化与余震分布的对应关系则比较复杂.以闽粤滨海断裂带为接收断层计算了其上的库仑应力变化,结果显示其西南段上的应力增加,促使其活动性增强,认为在闽粤滨海断裂带与NW走向的上杭-东山断裂交汇的南澎岛-东山岛海域发生地震的潜在危险性较大.     

Generation and evolution of internal solitary waves in the southern Taiwan Strait

ABSTRACT

The generation processes and potential energy sources of internal solitary waves (ISWs) in the southern Taiwan Strait are investigated by driving a high resolution non-hydrostatic numerical model with realistic background conditions. Two main types of ISWs are clarified according to their different energy sources. One is generated by the nonlinear disintegration of remote internal tides emanating from Luzon Strait, and the other type is generated by local tide-topography interaction at the continental slope. The basic properties and evolution processes differ between these two kinds of ISWs. The waves originated from the remote internal tides at Luzon Strait have amplitudes comparable to previous field observations. In contrast, the ISWs generated locally are much weaker than observed waves, even in the presence of a steady offshore background current, which intensifies the generation of onshore ISWs. The ISWs induced by remotely generated M₂ internal tides are stronger than those induced by K₁ internal tides, and the fraction of internal wave energy transmitted onto the shelf is not significantly influenced by the intensity of remotely generated internal tides.     

Effect of Seismicity in the Taiwan Straits on the Southeast Coastal Area of the Chinese Mainland

Based on the available and supplementary survey data,it analyzes the effect of seismicity in Taiwan and the Taiwan Straits on the southeastern coastal area of the Chinese mainland and discusses its roles in seismic hazard prevention and textual research of historical earthquakes. The results show that the frequency of strong earthquake in Taiwan area is high,with a time interval ranging from several to dozens of years,but the maximum influence intensity of seismicity from there to the coastal areas of the Chinese mainland is only VI degree; while the maximum influence intensity of the seismicity along the littoral fault zone located on the west of the straits reaches VIII ～ IX degree because of the shorter distance to the Chinese mainland,though the frequency of strong earthquakes is lower than that of the Taiwan area. Strategies for protecting against seismic hazards in the southeastern coastal area of China are proposed. Besides focusing on the effect of strong earthquakes of the littoral fault zone,attention also has to be paid to the low-cycle fatigue failure of engineering structures induced by the earthquakes in Taiwan and the stir effect on society induced by earthquake phobia. It is concluded that it would be more accurate and proper to take the May 19,1517 earthquake recorded in the Chinese mainland area as the influence of a strong earthquake in the Taiwan area.