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以马尼拉海沟的北断层发生MW8.0地震在南海引发海啸为假想的模拟情景， 利用E-FAST法定量分析了COMCOT海啸数值模型输出(最大海啸波高)对震级, 震源深度, 震中位置和断层走向、 倾角、 滑动角等震源参数的敏感性， 以及各震源参数间的交互效应对最大海啸波高的影响. 结果表明， 观测点B1( 20.1°N, 119.4°E)、 B2(18.4°N, 118.1°E)和B3(13.5°N, 117.6°E)的最大海啸波高都对震级十分敏感， 对震中位置、 断层走向和倾角较为敏感. 敏感的震源参数在影响上述3个观测点的最大海啸波高时， 与其它震源参数产生了较强的交互效应. 但是对于不同的观测点， 各震源参数的重要度排序则存在一定的差异. 该分析结果有助于更好地认识海啸波高与潜在海啸源参数之间的关系. 相似文献
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南海东南边缘的马尼拉海沟是国际上公认具有发生破坏性地震海啸条件的危险地区,由于南海没有大面积的岛屿阻隔海啸传播,如果在马尼拉海沟发生大地震引发海啸,那么将对广东省漫长的海岸线造成严重破坏。广东省南海地震海啸监测预警系统建设在广东省地震速报系统和国家地震自动速报备份系统的基础上,由地震速报、震源机制快速计算、海啸数值模拟计算等模块组成,对南海地震海啸进行实时监测,提供海啸波浪到达海岸线的估计时刻和最大海浪高度,提供预警信息等社会公共服务。 相似文献
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准确预估南海海啸风险是有效防灾减灾的前提.前人一般把弹性半无限空间背景下解算出来的海底位错直接等同于初始海啸分布，继而开展海啸传播过程研究.由于断层破裂并非瞬时完成，破裂过程会导致初始海啸波高小于海底位错量，即初始海啸衰减.本文基于高精度地形和高密度网格，求解非线性浅水方程，分别针对马尼拉断裂带的南段、中段和北段，构建南海海啸传播数值模型，试图定量考察初始海啸衰减作用对南海海啸的影响.模拟结果表明一定幅度的初始波高衰减将导致几乎相同幅度的海啸波高衰减，相应的偏差可以忽略.在保守的初始海啸衰减幅度(10%)下，模拟结果显示我国东南沿海、越南东部沿海和巴拉望岛为海啸危险区.另外，模型显示科里奥利力导致的波高变化幅度小于5 cm且其分布样式符合预期，这进一步佐证了数值模型的可靠性，也表明在实际南海海啸模拟中可以忽略科里奥利力进而提高计算效率.结合前人的沉积学认识和本文的数值模拟结果，本文认为南澳岛、西沙东岛和越南绥和周边曾同时遭受海啸侵袭，产生海啸的断裂带最有可能是马尼拉断裂带南段.后续有必要加强南澳岛、西沙东岛和越南东部的沉积学研究，识别更早的海啸事件，以期有力约束南海下次海啸事件的发生年... 相似文献
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马尼拉俯冲带是南海的东部边界，记录了南海形成演化的关键信息，同时也是地震和海啸多发区域.本文利用过马尼拉俯冲带北段的高分辨率多道地震剖面，分析了研究区内海盆和海沟的沉积特征，精细刻画了区内增生楔前缘的构造变形、结构以及岩浆活动特征.研究区内增生楔下陆坡部分由盲冲断层、构造楔和叠瓦逆冲断层构成，逆冲断层归并于一条位于下中新统的滑脱面上，滑脱面向海方向的展布明显受到增生楔之下埋藏海山和基底隆起的影响；上陆坡的反射特征则因变形强烈和岩浆作用而难以识别；岩浆活动开始于晚中新世末期并持续至第四纪.马尼拉俯冲带北段增生楔的形成时间早于16.5 Ma，并通过前展式逆冲向南海方向扩展；马尼拉俯冲带的初始形成时间可能在晚渐新世，而此时南海海盆扩张仍在持续.南海东北缘19°N-21°N区域为南海北部陆坡向海盆的延伸，高度减薄的陆壳的俯冲造成马尼拉海沟北段几何形态明显地向东凹进. 相似文献
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较大地震发生时,一些台站的记录振幅出格(亦称限幅),测定震级就很困难。本文使用了广州地震台四年来记录的台湾Ms≥4.0级的72次地震,通过用地震振动持续时间的方法,求得测定台湾地震震级(M_D)的公式。该方法有助于台站在记录波“限幅”或S波到时难于判定的特定条件下迅速测定震级,从而提高大震速报的质量。 相似文献
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本文整合了横跨马尼拉海沟北段的21条多道地震层位信息、海底地形以及天然地震数据,分析了研究区内的输入板块性质差异及其对增生楔变形和地震活动性的影响.研究发现,沿马尼拉海沟北段的输入板块在地壳性质、基底起伏和沉积物厚度上存在明显的自北向南的差异:(1)最北段基底埋深大,上覆沉积物厚,地壳厚度较薄,地壳性质可能为初始南海洋壳或者圈闭的菲律宾海洋壳;(2)中段基底埋深浅,上覆沉积物薄,地壳厚度大,地壳属性表现为过渡壳性质,受到岩浆活动的影响,初始的地壳性质可能为华南陆块张裂分离出的微小陆壳块体,或者是南海洋壳;(3)南段基底埋深和沉积物厚度介于中间,存在明显的地磁条带,地壳性质为正常的南海洋壳.这一输入板块性质的不均一性可解释该区的特殊增生楔变形现象,如恒春弱变形带的出现,向海方向内凹的海沟形态以及上陆坡海底的大幅抬升等,同时也影响了研究区内的板片俯冲形态和发震构造的地震活动性.研究结果证实了沿马尼拉海沟北段存在南北向的地球物理性质的差异,但对于地壳属性的最终厘定还需要更多的地质与地球化学证据. 相似文献
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南海地震与海啸 总被引：3，自引：0，他引：3
地震海啸的形成要具备3个条件:一是有深海盆地,可以容纳巨量海水;二是海底地形隆起与拗陷反差强烈;三是存在倾滑型活断层,可发生6级以上倾滑型的地震。查南海及其周边地形地貌,北西南三面都有宽阔的大陆架,中部又是平坦的深海平原,都不具备发生地震海啸的条件,惟独东侧马尼拉海沟才具备产生地震海啸的条件。南海地壳属于大洋型地壳与大陆型地壳之间的过度类型。其断裂构造非常发育,不同地段具有明显差异。北部为拉张型,南部为挤压型,西部为剪切型,东部为俯冲型,中部是扩张型。按断裂展布方向可分为NE向、NW向、EW向、SN向4组;按断裂切割深度,可分为岩石圈断裂、地壳断裂、基底断裂和盖层断裂。这些断裂多数为活动断裂,而东缘俯冲型断裂又是发震断裂。从地震分布、震源机制解分析,南海北、西、南以及中部都不具备引发地震海啸的条件,只有台南—菲律宾地震带东西两侧的贝尼奥夫带发生的倾滑型或具倾滑分量的走滑型6级以上地震,才有可能引发海啸,并可能对南海及我国东南沿海诸省以及港澳地区产生影响。 相似文献
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北京时间2011年3月11日13时46分(05:46 UTC)日本东北部近海(38.3°N,142.4°E)发生Mw9.0级特大地震,此次地震的强度为日本近1200a来最强.随后环太平洋的数十个国家和地区的验潮站和海啸监测浮标均监测到了强震引发的越洋海啸,海啸奔袭23 h到达南美洲的智利沿岸;此次海啸除了对近场的日本东北部沿岸地区造成了巨大灾害,还对太平洋东岸的部分国家和地区造成了一定程度的影响.地震发生4 h后海啸波到达我国台湾东部沿海,6~8 h海啸波到达我国大陆东南沿海,受此影响我国发布了第一份海啸蓝色警报.本文利用海啸数值模型对此次地震海啸的产生、越洋传播过程进行了数值模拟,给出了海啸波能量在我国近海及泛太平洋区域分布特征;同时重点模拟分析了海啸波在日本及中国近海传播的波动特征,模拟结果与观测数据吻合良好.最后通过对数值模拟结果的分析,阐述了此次海啸对中国的影响,给出了潜在的日本地震海啸对中国的风险估计. 相似文献
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Tsunami is one of the most devastating natural coastal disasters. Most of large tsunamis are generated by submarine earthquakes occurring in subduction zones. Tsunamis can also be triggered by volcano eruptions and large landslides. There are many records about "sea-overflow" in Chinese ancient books, which are not proved to be tsunamis. Tectonics and historical records analysis are import to forecast and prevention of tsunami. Consider the tectonic environment of the China sea, the possibility of huge damage caused by the offshore tsunami is very small. And the impact of the ocean tsunami on the Bohai sea, the Yellow sea, and the East China sea is also small. But in the South China Sea, the Manila subduction zone has been identified as a high hazardous tsunamigenic earthquake source region. No earthquake larger than MW7.6 has been recorded in the past 100a in this region, suggesting a high probability for larger earthquakes in the future. If a tsunamigenic earthquake were to occur in this region in the near future, a tragedy with the magnitude similar to the 2004 Indian Ocean tsunami could repeat itself. In this paper, based on tectonics and historical records analysis, we have demonstrated that potential for a strong future earthquake along the Manila subduction zone is real. Using a numerical model, we have also shown that most countries in the South China Sea will be affected by the tsunamis generated by the future earthquake. For China, it implies that the maximum wave height over 4.0 meter on China mainland, especially the Pearl River Estuary. But the island, local relief maybe influence the maximum wave. But it takes nearly 3 hours to attack China mainland, if there is the operational tsunami warning system in place in this region, should be greatly reduced losses. And the simulated results are conformable to historical records. It indicates that the tsunami hazards from Manila trench to China mainland worthy of our attention and prevention. 相似文献
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A Revised Evaluation of Tsunami Hazards along the Chinese Coast in View of the Tohoku-Oki Earthquake
Huimin Helen Jing Huai Zhang David A. Yuen Yaolin Shi 《Pure and Applied Geophysics》2013,170(1-2):129-138
Japan’s 2011 Tohoku-Oki earthquake and the accompanying tsunami have reminded us of the potential tsunami hazards from the Manila and Ryukyu trenches to the South China and East China Seas. Statistics of historical seismic records from nearly the last 4 decades have shown that major earthquakes do not necessarily agree with the local Gutenberg-Richter relationship. The probability of a mega-earthquake may be higher than we have previously estimated. Furthermore, we noted that the percentages of tsunami-associated earthquakes are much higher in major events, and the earthquakes with magnitudes equal to or greater than 8.8 have all triggered tsunamis in the past approximately 100 years. We will emphasize the importance of a thorough study of possible tsunami scenarios for hazard mitigation. We focus on several hypothetical earthquake-induced tsunamis caused by M w 8.8 events along the Manila and Ryukyu trenches. We carried out numerical simulations based on shallow-water equations (SWE) to predict the tsunami dynamics in the South China and East China Seas. By analyzing the computed results we found that the height of the potential surge in China’s coastal area caused by earthquake-induced tsunamis may reach a couple of meters high. Our preliminary results show that tsunamis generated in the Manila and Ryukyu trenches could pose a significant threat to Chinese coastal cities such as Shanghai, Hong Kong and Macao. However, we did not find the highest tsunami wave at Taiwan, partially because it lies right on the extension of an assumed fault line. Furthermore, we put forward a multi-scale model with higher resolution, which enabled us to investigate the edge waves diffracted around Taiwan Island with a closer view. 相似文献
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— Simulation of tsunami propagation and runup of the 1998 Papua New Guinea (PNG) earthquake tsunami using the detailed bathymetry measured by JAMSTEC and adding bathymetric data at depths less than 60 m is carried out, reproducing the tsunami energy focus into Warapu and Arop along the Sissano Lagoon. However, the computed runup heights in the lagoon are still lower than those measured. Even if the error in estimating the fault parameters is taken into consideration, computational results are similar. Analysis by the wave ray method using several scenarios of the source size of the tsunami and location by the wave ray method suggests that a source characterized by small size in water 1,000-m deep approximately 25 km offshore the lagoon, best fits the arrival determined from the interviews with eyewitnesses. A two-layer numerical model simulating the interaction of the tsunami with a landslide is employed to study the behavior of a landslide-generated tsunami with different size sand depths of the initial slide just outside the lagoon. A landslide model with a volume of 4–8 × 109 m3 is selected as the best in order to reproduce the distribution of the measured tsunami runup in the lagoon. The simulation of a tsunami generated in two stages, fault and landslide, could show good agreement with the runup heights and distribution of the arrival time, but a time gap of around 10 minutes remains, suggesting that a tsunami generated by the mainshock at 6:49 PM local time is too small for people to notice, and the following tsunami triggered by landslide or mass movement near the lagoon about ten minutes after the mainshock attacked the coast and caused the huge damage. 相似文献
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南海北部区域现今地应力场的状态和分布特征是进行海洋资源开发、地质环境和工程安全评价的主要参考依据，也是地球动力学研究的主要内容之一. 由于受到测量技术水平和自然条件等因素的影响，整个南海海域的地应力研究程度还比较低，有待于对该区域的地应力场的状态和控制因素进行较深入和细致的研究. 原地地应力测量是直接获取地壳浅表层现今主应力大小和方向特征的有效途径，同时利用海上油气田测井FMI资料能够有效地提取地应力信息. 结合区域构造环境，在实测地应力约束条件下，数值模拟方法能够有效地推测区域地应力的状态和分布特征. 在海南省乐东县开展了水压致裂原地地应力测量，测量获得的最大主应力方向区间为NW-NWW向. 根据Byerlee准则判别，钻孔附近的地应力远远小于引起断层活动地应力值的下限，钻孔邻近区域的断层活动性较弱. 对南海北部边缘海盆地有限的FMI测井资料进行地应力解译，获得莺歌海的最大主应力优势方位为NW-NNW向，琼东南的最大主应力优势方位为NWW向. 在对南海海域北部区域的板块构造环境和地球动力学背景分析的基础上，以上述地应力观测数据以及震源机制解资料为约束，对该区域现今地应力场进行了数值模拟分析，模拟结果表明，由于受印度板块、菲律宾板块和欧亚板块不同程度的影响，南海北部区域的地应力分布特征呈现了不同区域分化的趋势. 在靠近台湾岛区域，主要受到菲律宾板块与欧亚板块发生碰撞的影响，最大主应力方向为近E-W向；沿着滨海海岸带向西，由于受到欧亚板块在马尼拉海沟向下俯冲形成的拉伸作用，最大主应力的方向逐渐转换为S-N向、NW向. 相似文献
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在东海潜在震源区冲绳海槽假定了五个震源点,根据Steven地震海啸地震参数经验值作为初始条件,分别考虑6.5、7.0、7.5、8.0、8.5、9.0级地震条件下的30个震例,采用数值模拟的方法,对海啸在东海传播过程进行情境分析,特别是对上海沿岸地区可能会遭受的海啸灾害做了较为精细的研究.结果发现:小于8.0级的震例对上海地区几乎不会造成影响;8.0级震例只有最北端震源点震例会对上海地区有明显影响;8.5级以及9.0级震级基本上均会对上海沿岸地区造成较大的影响.特别是冲绳海槽北段9.0级震例可能会对上海沿岸局部地区造成危害,最大波高可达3.9m. 相似文献
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The Transoceanic 1755 Lisbon Tsunami in Martinique 总被引：1，自引：0，他引：1
J. Roger M. A. Baptista A. Sahal F. Accary S. Allgeyer H. H��bert 《Pure and Applied Geophysics》2011,168(6-7):1015-1031
On 1 November 1755, a major earthquake of estimated M w=8.5/9.0 destroyed Lisbon (Portugal) and was felt in the whole of western Europe. It generated a huge transoceanic tsunami that ravaged the coasts of Morocco, Portugal and Spain. Local extreme run-up heights were reported in some places such as Cape St Vincent (Portugal). Great waves were reported in the Madeira Islands, the Azores and as far as the Antilles (Caribbean Islands). An accurate search for historical data allowed us to find new (unpublished) information concerning the tsunami arrival and its consequences in several islands of the Lesser Antilles Arc. In some places, especially Martinique and the Guadeloupe islands, 3?m wave heights, inundation of low lands, and destruction of buildings and boats were reported (in some specific locations probably more enclined to wave amplification). In this study, we present the results of tsunami modeling for the 1755 event on the French island of Martinique, located in the Lesser Antilles Arc. High resolution bathymetric grids were prepared, including topographic data for the first tens of meters from the coastline, in order to model inundations on several sites of Martinique Island. In order to reproduce as well as possible the wave coastal propagation and amplification, the final grid was prepared taking into account the main coastal features and harbour structures. Model results are checked against historical data in terms of wave arrival, polarity, amplitude and period and they correlate well for Martinique. This study is a contribution to the evaluation of the tele-tsunami impact in the Caribbean Islands due to a source located offshore of Iberia and shows that an 8.5 magnitude earthquake located in the northeastern Atlantic is able to generate a tsunami that could impact the Caribbean Islands. This fact must be taken into account in hazard and risk studies for this area. 相似文献
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菲律宾群岛受到欧亚板块、菲律宾海板块和印度-澳大利亚板块的碰撞作用，地质环境复杂，构造因素多样.尽管近几年来已经有了少数关于该区域层析成像的研究，但这些研究的区域主要集中在马尼拉海沟、吕宋岛及中菲律宾地区，而关于群岛周围其他海沟和南菲律宾地区的讨论相对较少.到目前为止，还没有同时获得过关于菲律宾群岛深部纵、横波速度结构的研究，本次研究通过反演155779条P波震相和59642条S波震相，同时获得了菲律宾群岛从地表至150 km深度的纵、横波速度结构.地震层析成像结果表明该地区的壳幔速度结构具有较强的不均一性，地壳内部存在着广泛的低速异常，而表征俯冲板块的高速异常则沿着群岛周边的海沟展布.南海块体在马尼拉海沟中段的俯冲角度和俯冲活动性比南段小；菲律宾海板块在东吕宋海槽南段微弱的俯冲作用很有可能同本哈姆海台的碰撞有关.菲律宾群岛大部分MW>6.0的强震沿着各个板块的边界发生，体现出菲律宾海板块同欧亚板块之间的强耦合作用，群岛西侧的南海块体在马尼拉海沟16°N-20°N之间呈现出的弱耦合状态可能跟北吕宋地区的拉张应力环境有关，南海块体在16°N以南的地区同上覆块体之间的耦合作用较强；群岛东侧的菲律宾海板块在14°N以北的地区没有强震发生，它与菲律宾群岛之间的耦合程度从北向南逐渐增强，在12°N以南的地区要强于12°N以北的地区；此外苏禄海盆和菲律宾构造带之间也存在着强耦合关系. 相似文献
19.
基于日本南海海槽地震活动性和历史海啸事件记载的分析，本文对日本南海海槽发生MW9.1罕遇地震情况下的海啸进行了数值模拟研究.结果表明:该地震可引发初始波幅约10 m的海啸，6个小时后传至浙江沿海，近岸各处波幅为1—2 m；8个小时后靠近上海海岸线，最大波幅约2 m，受地形影响局地爬高至近3 m；11个小时后抵达苏北黄海沿岸，预计波幅普遍在1 m左右.海啸的上岸高度与海岸附近的海深和海岸线的形态密切相关.我国近岸海域地形变化复杂，海湾众多，对海啸波有放大作用，该模拟结果可能比实际传播到近岸时偏小，因此综合评估日本海啸影响我国华东地区的规模m可达1—2级左右.一旦日本南海发生罕遇地震对我国的影响不容忽视，尤其遇上风暴潮与天文大潮叠加，则可能会造成一定程度的海啸灾害. 相似文献