山东沿海地区地震海啸研究

地震海啸是一种极其严重的地震次生灾害。山东是世界上最早记录地震海啸的地区。收集整理了山东沿海地区记载的7次地震海啸史料,对每次地震海啸进行了信度评级,认为仅有一次可能是海啸。根据山东沿海地区历史地震海啸、地震类型、沿海地理环境、现代地震海啸记录资料等分析,表明山东沿海未来遭受破坏性地震海啸的可能性较小。     

东海潜在地震海啸特点

主要从东海发生地震海啸的可能性分析,海啸传播过程的特点以及发生概率几个方面重点阐述讨论了东海地震海啸的一些特性,并分析了地震海啸在东海发生的概率及其特点。得出东海潜在海啸源区主要位于冲绳海槽内,数值模拟海啸在东海的传播过程方程应采用球坐标系下的线性方程,对于近岸的传播包括上岸部分的研究应该采用笛卡儿坐标系下的非线性方程,并且要考虑底部摩擦等项的对波浪的衰减作用。     

近期海啸研究对地震研究的启发

近期海啸研究对地震研究的启发佐竹健治在一年当中，３次重大破坏性海啸给尼加拉瓜（１９９２年９月２日）、印度尼西亚弗洛勒斯岛（１９９２年１０月１２日）和日本北海道（１９９３年７月１２日）的沿海地区造成了灾害。每次海啸的浪高度均达到１０ｍ以上，共造成１５０...     

地震海啸灾害及其研究概述

１９９８年７月１７日,西北太平洋巴布亚新几内亚近海地区发生７．１级地震,并引发海啸,造成严重的生命和财产损失,约有３０００－５００人死亡或失踪,５座村庄被巨浪蚕没,本文介绍了这次地震海啸破坏情况,国内外历史上大地震海啸灾害,简述了有关专家对巴地地震海啸追踪研究的初步结果和评论。     

2010年智利地震海啸数值模拟及其对我国沿海的影响分析

2010年2月27日06时34分(北京时间14时34分),在智利中南部近岸(36.1°S,72.6°W)发生Mw8.8级地震,并引发了泛太平洋范围的海啸,太平洋沿岸多个国家的验潮站和海啸监测浮标均监测到了强震引发的海啸;海啸波传播25 h后到达我国沿海.本文利用海啸数值模型对此次地震海啸进行了数值模拟.重点模拟了我国沿...     

中国古籍中的地震海啸记录

2004年12月26日的印度洋地震海啸波及10国，造成20余万人死亡和失踪、50万人受伤、100万人流离失所的浩劫，引发了人们对海洋地震灾害的关注。建立海啸预警系统的呼声也日趋强烈。我国海岸线长达32000km，我国的经济重心又相对集中在沿海地区，产业发达，人烟稠密，人们自然会对海啸表示相当的关注。本文在查阅大量地震史料的基础上，发现我国也有地震海啸发生，但除台湾外，其他地区并不严重，概率较低。为防患于未然，对我国自身的地震预警系统也应适当予以关注。     

加勒比海北部地区的海啸高危险性

2004年12月26日苏门答腊地震(Mw=9．3)夺走了印度洋沿岸7个不同国家沿海地区30万人的生命。此次事件提出了这样一个问题，即类似的板块边界断层作用引起的传播极远的海啸是否会影响美国约1．5亿沿海居住人口的生命安全，包括阿拉斯加、夏威夷、波多黎各以及美属维尔京群岛。     

冲绳海槽地区地震潜在海啸对中国东南沿海的影响研究

采用球坐标系下非线性浅水波方程, 研究日本本州M9.0大地震引发的海啸对中国东南沿海的影响, 并计算了冲绳海槽构造带上3个不同段落可能发生潜在地震引发的海啸, 分析这些海啸与日本大海啸的浪高和走时关系. 结果表明, 日本地震海啸模拟结果与日本当地报道及中国东南沿海7个验潮站的报道结果相符. 冲绳海槽构造带中段可能发生的3次不同震级（M7.0, M7.5, M8.0）潜在地震引发的海啸到达中国东南沿海的时间比日本海啸提前约4个小时, 从震源区传播3个多小时即可到达华东沿海部分验潮站. 冲绳海槽M7.5潜在地震海啸在验潮站上计算的波高与日本海啸相当, 中冲绳海槽M8.0潜在地震海啸在大陈站的波高将超过0.9 m, 在坎门站波高将超过1.8 m. 北冲绳海槽的潜在地震海啸威胁主要集中在江苏盐城、 上海一带, 南冲绳海啸主要对台湾东北部和浙江沿海产生威胁. 本文对冲绳海槽构造带上潜在地震引发海啸的模拟结果, 可为中国东南沿海地区的防震减灾、 海啸预警提供有意义的参考.      

香港海啸监测及警报系统的发展

地震监测、海啸数值模拟和海平面监测是监测和预报海啸的主要工具。为了有效监测南海北部可能发生的地震海啸,香港天文台（HKO）正在香港筹建一个宽频地震站,同时通过太平洋海啸警报及减灾系统（PTWS）的框架取得美国加州综合地震网（CISN）显示系统的实时地震信息,并通过世界气象组织（WM0）的全球通信系统（GTS）接收南海和西北太平洋的验潮站和海啸浮标数据以监测海面的波动情况。香港天文台通过联合国教科文组织（UNESCO）政府间海洋学委员会（IOC）取得海啸漫滩模式交换计划（TIME）下的海啸数值模式,把香港本地的高分辨率水深和地形数据融合在模式之内,并利用这个模式计算南海多处地区在不同地震情景下的海啸传播,为海啸预报提供重要的参考数据。     

基于强震台网的我国沿海海啸走时预警

经济快速发展的中国沿海地区,面临着潜在海啸袭击危险。海啸传播走时分析是海啸预警系统的重要组成部分。本文基于强震台网提供的地震要素,从理论上讨论海啸预警时间计算方法。在球坐标系下,建立了远洋海啸传播模型,采用差分技术,实现远洋海啸传播数值模拟,首次针对我国主要城市进行了海啸走时计算,分析了我国沿海走时特点,指出了未来发生在太平洋的远洋海啸对我国的长江三角洲会有较大影响。本文计算海啸走时方法可以为我国建设的新一代基于数值海啸预警系统提供技术支持。     

Stochastic coupled simulation of strong motion and tsunami for the 2011 Tohoku,Japan earthquake

This study conducts coupled simulation of strong motion and tsunami using stochastically generated earthquake source models. It is focused upon the 2011 Tohoku, Japan earthquake. The ground motion time-histories are simulated using the multiple-event stochastic finite-fault method, which takes into account multiple local rupture processes in strong motion generation areas. For tsunami simulation, multiple realizations of wave profiles are generated by evaluating nonlinear shallow water equations with run-up. Key objectives of this research are: (i) to investigate the sensitivity of strong motion and tsunami hazard parameters to asperities and strong motion generation areas, and (ii) to quantify the spatial variability and dependency of strong motion and tsunami predictions due to common earthquake sources. The investigations provide valuable insights in understanding the temporal and spatial impact of cascading earthquake hazards. Importantly, the study also develops an integrated strong motion and tsunami simulator, which is capable of capturing earthquake source uncertainty. Such an advanced numerical tool is necessary for assessing the performance of buildings and infrastructure that are subjected to cascading earthquake–tsunami hazards.     

Validation and Joint Inversion of Teleseismic Waveforms for Earthquake Source Models Using Deep Ocean Bottom Pressure Records: A Case Study of the 2006 Kuril Megathrust Earthquake

The importance of accurate tsunami simulation has increased since the 2004 Sumatra-Andaman earthquake and the Indian Ocean tsunami that followed it, because it is an important tool for inundation mapping and, potentially, tsunami warning. An important source of uncertainty in tsunami simulations is the source model, which is often estimated from some combination of seismic, geodetic or geological data. A magnitude 8.3 earthquake that occurred in the Kuril subduction zone on 15 November, 2006 resulted in the first teletsunami to be widely recorded by bottom pressure recorders deployed in the northern Pacific Ocean. Because these recordings were unaffected by shallow complicated bathymetry near the coast, this provides a unique opportunity to investigate whether seismic rupture models can be inferred from teleseismic waves with sufficient accuracy to be used to forecast teletsunami. In this study, we estimated the rupture model of the 2006 Kuril earthquake by inverting the teleseimic waves and used that to model the tsunami source. The tsunami propagation was then calculated by solving the linear long-wave equations. We found that the simulated 2006 Kuril tsunami compared very well to the ocean bottom recordings when simultaneously using P and long-period surface waves in the earthquake source process inversion.     

设定琉球海沟发生罕遇地震评估我国东南沿海地区的海啸风险

根据构造相似条件分析,琉球海沟与日本海沟、智利海沟、印尼巽他海沟一样具备发生9级罕遇超巨大地震的可能。在对近几年来全球发生的超巨大地震参数及构造对比分析的基础上,设定琉球海沟9.0级地震参数,并将其引发的海啸进行数值模拟研究。结果表明,该地震可引发初始波高为8m的海啸,台湾东北部半小时后遭受10m以上海啸,3~4小时左右传至浙南、闽北沿岸,近岸各处波高在1~2m;5小时左右传至浙北、粤北沿岸,浙江近岸各处波高在2m左右,广东沿海、台湾海峡由于台湾岛的正面阻挡,海啸波高低于50cm;8小时后靠近上海海岸线,最大波高约1m。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,我国东南海域地形变化复杂、海湾众多,对海啸波有放大作用,模拟结果可能比实际海啸偏小。我国沿海地区分布着不少已建和在建的核电厂,在核电设计时未考虑海啸,一旦发生这种罕遇地震海啸则影响不可忽视,尤其是若与风暴潮、天文大潮叠加则可能出现严重后果。由于核电安全要求万无一失,故须制订有效预警和应对措施。     

Tsunami Source of the 2010 Mentawai, Indonesia Earthquake Inferred from Tsunami Field Survey and Waveform Modeling

The 2010 Mentawai earthquake (magnitude 7.7) generated a destructive tsunami that caused more than 500 casualties in the Mentawai Islands, west of Sumatra, Indonesia. Seismological analyses indicate that this earthquake was an unusual “tsunami earthquake,” which produces much larger tsunamis than expected from the seismic magnitude. We carried out a field survey to measure tsunami heights and inundation distances, an inversion of tsunami waveforms to estimate the slip distribution on the fault, and inundation modeling to compare the measured and simulated tsunami heights. The measured tsunami heights at eight locations on the west coasts of North and South Pagai Island ranged from 2.5 to 9.3 m, but were mostly in the 4–7 m range. At three villages, the tsunami inundation extended more than 300 m. Interviews of local residents indicated that the earthquake ground shaking was less intense than during previous large earthquakes and did not cause any damage. Inversion of tsunami waveforms recorded at nine coastal tide gauges, a nearby GPS buoy, and a DART station indicated a large slip (maximum 6.1 m) on a shallower part of the fault near the trench axis, a distribution similar to other tsunami earthquakes. The total seismic moment estimated from tsunami waveform inversion was 1.0 × 10²¹ Nm, which corresponded to M_w 7.9. Computed coastal tsunami heights from this tsunami source model using linear equations are similar to the measured tsunami heights. The inundation heights computed by using detailed bathymetry and topography data and nonlinear equations including inundation were smaller than the measured ones. This may have been partly due to the limited resolution and accuracy of publically available bathymetry and topography data. One-dimensional run-up computations using our surveyed topography profiles showed that the computed heights were roughly similar to the measured ones.     

W Phase Inversion and Tsunami Inundation Modeling for Tsunami Early Warning: Case Study for the 2011 Tohoku Event

Centroid moment tensor solutions for the 2011 Tohoku earthquake are determined by W phase inversions using 5 and 10 min data recorded by the Full Range Seismograph Network of Japan (F-net). By a scaling relation of moment magnitude to rupture area and an assumption of rigidity of 4 × 10¹⁰ N m^?2, simple rectangular earthquake fault models are estimated from the solutions. Tsunami inundations in the Sendai Plain, Minamisanriku, Rikuzentakata, and Taro are simulated using the estimated fault models. Then the simulated tsunami inundation area and heights are compared with the observations. Even the simulated tsunami heights and inundations from the W phase solution that used only 5 min data are considerably similar to the observations. The results are improved when using 10 min of W phase data. These show that the W phase solutions are reliable to be used for tsunami inundation modeling. Furthermore, the technique that combines W phase inversion and tsunami inundation modeling can produce results that have sufficient accuracy for tsunami early warning purposes.     

EFFECT OF TSUNAMIS GENERATED IN THE MANILA TRENCH ON CHINA MAINLAND

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 M_W7.6 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.     

海啸及其在核电厂选址中的安全评价

海啸大小的量度应包括关于海啸“源”处大小的描述,“源”处海啸的大小与地壳形变规模和方式有着直接的关系。在海啸与地震的关系中,除了地震震级外,强调了震源破裂方式这一因素。阐述了关于核电厂选址安全评价中历史资料的整理、分析,对未来海啸“源”的预测、海啸传播路径的调查和分析以及综合评价等4个方面进行了讨论     

海啸波近岸共振响应的数值模拟及分析

应用有限差分方法求解非线性浅水长波方程,建立了海啸波产生和传播的二维数值模型;对太平洋地震引起的夏威夷群岛海啸波进行模拟,并将模拟结果和测站实测值进行比较,验证了模型的正确性。利用快速傅里叶变换对数值模拟结果进行谱分析,得到整个计算区域的能量谱分布,并给出了发生能量聚集的位置及相应的谱峰周期。讨论了海啸波传播到近岸时可能产生的共振响应现象,发现海啸波和近岸的共振响应不仅与近岸复杂地形有关,还与海啸波传播到近岸时的波浪入射方向有关。     

海底地震有限断层破裂模型对近场海啸数值预报的影响

快速准确的海啸源模型是近场海啸精确预警的关键.尽管目前还没有办法直接对其进行正演定量计算,但是可以通过多源地震、海啸观测数据进行反演或联合反演推算.不同的海啸源可能导致不同的预警结论,了解不同类型海啸源适用性、评估海啸源特征差异对近场海啸的影响,无论对于海啸预警还是海啸模拟研究尤为重要.本文评估分析了6种不同同震断层模型对2011年3月11日日本东北地震海啸近场数值预报的影响,重点对比分析了有限断层模型与均一滑动场模型对近场海啸产生、传播、淹没特征的影响及各自的误差.研究表明:近场海啸波能量分布主要取决于海啸源分布特征,特别是走向角的差异对海啸能量分布影响较大;有限断层模型对海啸灾害最为严重的39°N以南沿岸地区的最大海啸爬坡高度明显优于均一滑动场模型结果;综合对比DART浮标、GPS浮标及近岸潮位站共32个站次的海啸波幅序列结果发现有限断层模型整体平均绝对/相对误差比均一滑动场模型平均误差要低,其中Fujii海啸源的平均绝对/相对误差最小,分别是0.56m和26.71%.UCSB海啸源的平均绝对/相对误差次之.3个均一滑动场模型中USGSCMT海啸源模拟精度最高.相对于深海、浅海观测站,有限断层模型比均一滑动场模型对近岸观测站计算精度更高.海啸源误差具有显著的方向性,可能与反演所采用的波形数据的代表性有关;谱分析结果表明Fujii海啸源对在12至60min主频波谱的模拟要优于UCSB海啸源.海啸源中很难真实反映海底地震破裂过程,然而通过联合反演海啸波形数据推算海啸源的方法可以快速确定海啸源,并且最大限度的降低地震破裂过程与海啸产生的不确定性带来的误差.