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1.
Numerical Simulations of Tsunami Waves and Currents for Southern Vancouver Island from a Cascadia Megathrust Earthquake 总被引：1，自引：0，他引：1
Josef Y. Cherniawsky Vasily V. Titov Kelin Wang Jing-Yang Li 《Pure and Applied Geophysics》2007,164(2-3):465-492
The 1700 great Cascadia earthquake (M = 9) generated widespread tsunami waves that affected the entire Pacific Ocean and caused
damage as distant as Japan. Similar catastrophic waves may be generated by a future Cascadia megathrust earthquake. We use
three rupture scenarios for this earthquake in numerical experiments to study propagation of tsunami waves off the west coast
of North America and to predict tsunami heights and currents in several bays and harbours on southern Vancouver Island, British
Columbia, including Ucluelet, located on the west coast of the island, and Victoria and Esquimalt harbours inside Juan de
Fuca Strait. The earthquake scenarios are: an 1100-km long rupture over the entire length of the subduction zone and separate
ruptures of its northern or southern segments. As expected, the southern earthquake scenario has a limited effect over most
of the Vancouver Island coast, with waves in the harbours not exceeding 1 m. The other two scenarios produce large tsunami
waves, higher than 16 m at one location near Ucluelet and over 4 m inside Esquimalt and Victoria harbours, and very strong
currents that reach 17 m/s in narrow channels and near headlands. Because the assumed rupture scenarios are based on a previous
earthquake, direct use of the model results to estimate the effect of a future earthquake requires appropriate qualification. 相似文献
2.
Field Survey of the 27 February 2010 Chile Tsunami 总被引：1，自引：0，他引：1
Hermann M. Fritz Catherine M. Petroff Patricio A. Catal��n Rodrigo Cienfuegos Patricio Winckler Nikos Kalligeris Robert Weiss Sergio E. Barrientos Gianina Meneses Carolina Valderas-Bermejo Carl Ebeling Athanassios Papadopoulos Manuel Contreras Rafael Almar Juan Carlos Dominguez Costas E. Synolakis 《Pure and Applied Geophysics》2011,168(11):1989-2010
On 27 February 2010, a magnitude M w?=?8.8 earthquake occurred off the coast of Chile??s Maule region causing substantial damage and loss of life. Ancestral tsunami knowledge from the 1960 event combined with education and evacuation exercises prompted most coastal residents to spontaneously evacuate after the earthquake. Many of the tsunami victims were tourists in coastal campgrounds. The international tsunami survey team (ITST) was deployed within days of the event and surveyed 800?km of coastline from Quintero to Mehuín and the Pacific Islands of Santa María, Mocha, Juan Fernández Archipelago, and Rapa Nui (Easter). The collected survey data include more than 400 tsunami flow depth, runup and coastal uplift measurements. The tsunami peaked with a localized runup of 29?m on a coastal bluff at Constitución. The observed runup distributions exhibit significant variations on local and regional scales. Observations from the 2010 and 1960 Chile tsunamis are compared. 相似文献
3.
Amr Z. Hamouda 《Acta Geophysica》2010,58(4):687-704
The historical tsunamigenic event of 21 July AD 365 destroyed several coastal locations in the Eastern Mediterranean region.
The foremost destructive impacts were recorded in Crete and Egypt. The present study re-examines the effect of location, direction,
height and time of travel of the tsunami towards the Egyptian coast. Evidently, this tsunamigenic event is related to an earthquake
which is identified with a Hellenic Arc subduction-zone event of great magnitude, M > 8, as manifested by up to 9 m uplift
in western Crete. The maximum run-up height distribution in the front of the Nile Delta was about 9.5 m in Alexandria, while
those of the neighboring cities were 7.1 m, 4.9 m, and 1.9 m at Rashid, Damietta and El-Arish, respectively. Data obtained
from this study is essential to evaluate the tsunami hazards along the Egyptian coast. 相似文献
4.
The boundary between the Pacific and North America plates along Canada’s west coast is one of the most seismically active regions of Canada, and is where Canada’s two largest instrumentally recorded earthquakes have occurred. Although this is a predominantly strike-slip transform fault boundary, there is a component of oblique convergence between the Pacific and North America plates off Haida Gwaii. The 2012 Mw 7.7 Haida Gwaii earthquake was a thrust event that generated a tsunami with significant run up of over 7 m in several inlets on the west coast of Moresby Island (several over 6 m, with a maximum of 13 m). Damage from this earthquake and tsunami was minor due to the lack of population and vulnerable structures on this coast. 相似文献
5.
The Gulf of Cadiz coasts are exposed to tsunamis. Emergency planning tools are now taking into account this fact, especially because a series of historical occurrences were strikingly significant, having left strong evidence behind, in the mareographic records, the geological evidence or simply the memory of the populations. The study area is a strip along the Algarve coast, south Portugal, an area known to have been heavily impacted by the 1 November 1755 event. In this study we use two different tsunami scenarios generated by the rupture of two thrust faults identified in the area, corresponding to 8.1?C8.3 magnitude earthquakes. Tsunami propagation and inundation computation is performed using a non-linear shallow water code with bottom friction. Numerical modeling results are presented in terms of flow depth and current velocity with maximum values of 7?m and 8?m/s for inundation depth and flow speed, respectively. These results constitute a valuable tool for local authorities, emergency and decision planners to define the priority zones where tsunami mitigation measures must be implemented and to develop tsunami-resilient communities. 相似文献
6.
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。 相似文献
7.
Preliminary numerical simulation of potential earthquake-induced tsunami in East China Sea 总被引：1，自引：0，他引：1
In this paper,we present a numerical simulation of the propagation of a tsunami in the East China Sea,which might be induced by a hypothetical M8.5 earthquake in Okinawa Trough. Our results show that the initial maxi-mum wave height of tsunami could reach as high as 4.3 m for the hypothetical earthquake. It would take 3.5～4 hours for the tsunami to propagate to the coast of Zhejiang Province,and 7～8 hours to the near-shore of Shanghai. The peak tsunami height could be up to about 2 m in the coast of Zhejiang Province. Based on the numerical ex-periments,we plot the arrival time contours of tsunami in East China Sea and time history curves on the three ob-servational stations,and discussed the significance of the pre-analysis. 相似文献
8.
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
9.
Toshitaka Baba Richard Mleczko David Burbidge Phil R. Cummins Hong Kie Thio 《Pure and Applied Geophysics》2008,165(11-12):2003-2018
The effect of offshore coral reefs on the impact from a tsunami remains controversial. For example, field surveys after the 2004 Indian Ocean tsunami indicate that the energy of the tsunami was reduced by natural coral reef barriers in Sri Lanka, but there was no indication that coral reefs off Banda Aceh, Indonesia had any effect on the tsunami. In this paper, we investigate whether the Great Barrier Reef (GBR) offshore Queensland, Australia, may have weakened the tsunami impact from the 2007 Solomon Islands earthquake. The fault slip distribution of the 2007 Solomon Islands earthquake was firstly obtained by teleseismic inversion. The tsunami was then propagated to shallow water just offshore the coast by solving the linear shallow water equations using a staggered grid finite-difference method. We used a relatively high resolution (approximately 250 m) bathymetric grid for the region just off the coast containing the reef. The tsunami waveforms recorded at tide gauge stations along the Australian coast were then compared to the results from the tsunami simulation when using both the realistic 250 m resolution bathymetry and with two grids having fictitious bathymetry: One in which the the GBR has been replaced by a smooth interpolation from depths outside the GBR to the coast (the “No GBR” grid), and one in which the GBR has been replaced by a flat plane at a depth equal to the mean water depth of the GBR (the “Average GBR” grid). From the comparison between the synthetic waveforms both with and without the Great Barrier Reef, we found that the Great Barrier Reef significantly weakened the tsunami impact. According to our model, the coral reefs delayed the tsunami arrival time by 5–10 minutes, decreased the amplitude of the first tsunami pulse to half or less, and lengthened the period of the tsunami. 相似文献
10.
More damaging tsunamis have impacted Crescent City, California in historic times than any other location on the West Coast of the USA. Crescent City??s harbor has undergone significant modification since the early 20th century, including construction of several breakwaters, dredging, and a 200?×?300?m2 small boat basin. In 2006, a M w 8.3 earthquake in the Kuril Islands generated a moderate Pacific-wide tsunami. Crescent City recorded the highest amplitudes of any tide gauge in the Pacific and was the only location to experience structural damage. Strong currents damaged docks and boats within the small boat basin, causing more than US?$20 million in damage and replacement costs. We examine how modifications to Crescent City??s harbor may have affected its vulnerability to moderate tsunamis such as the 2006 event. A bathymetric grid of the basin was constructed based on US Army Corps of Engineers soundings in 1964 and 1965 before the construction of the small boat basin. The method of splitting tsunamis was used to estimate tsunami water heights and current velocities at several locations in the harbor using both the 1964?C1965 grid and the 2006 bathymetric grid for the 2006 Kuril event and a similar-sized source along the Sanriku coast of Japan. Model velocity outputs are compared for the two different bathymetries at the tide gauge location and at six additional computational sites in the harbor. The largest difference between the two grids is at the small boat basin entrance, where the 2006 bathymetry produces currents over three times the strength of the currents produced by the 1965 bathymetry. Peak currents from a Sanriku event are comparable to those produced by the 2006 event, and within the boat basin may have been higher. The modifications of the harbor, and in particular the addition of the small boat basin, appear to have contributed to the high current velocities and resulting damage in 2006 and help to explain why the 1933 M w 8.4?C8.7 Sanriku tsunami caused no damage at Crescent City. 相似文献
11.
1605年琼山强地震导致的同震海岸快速下沉、可能紧随的海啸及其证据 总被引：5，自引：0，他引：5
根据琼州府志、琼山县志及一些家谱、族谱等的记载,再加上对海域中退潮后海底残留的房屋、坟墓等各种沉没于海的人类活动废墟和东寨港海域中地震地貌的发现与考察,结合本人和前人以往的研究成果,证实1605年7月13日海南岛琼山县发生的71/2级强地震导致琼州海峡东南侧与琼北陆地相连的海底及与海相连的琼北东部一些沿岸陆地大面积同震快速下沉,使得原先为陆地的东寨港、北创港和舖前港及其以北海域等地区大面积陆陷成海。这是一次生源地在与海相连的海岸带的同震海岸下沉。推断了这次地震海啸;比较了这次陆陷成海地震海啸与生源地在近海和大洋海底的地震海啸的异同;也与北美西海岸生源地在太平洋板块斜插在北美大陆板块之下形成消减带的海岸同震下沉及海啸比较了异同。最后还提出,琼州大地震陆陷成海灾害应从根本上区别通常所说的震陷灾害。 相似文献
12.
2014年3月10日13时18分(北京时间)美国加利福尼亚州西北岸发生Mw6.9级地震,震中位于戈尔达板块内部.本文利用国际地震学研究联合会(IRIS)地震数据中心提供的远场体波数据,通过波形反演的方法来研究此次地震的震源破裂过程,并分析未造成重大人员伤亡及诱发海啸的原因,为该地区地球动力学的研究提供依据.选取19个方位角覆盖均匀的远场P波垂向波形记录和13个近场P波初动符号进行约束,基于剪切位错点源模型确定此次地震的震源机制解.结合地质构造背景资料,确定断层破裂面的走向.在考虑海水层多次反射效应的影响下,采用18个远场P波垂向波形数据和21个远场SH波切向波形数据,利用有限断层模型,将断层面剖分为17×9块子断层单元来模拟破裂面上滑动的时空分布,通过波形反演的方法获得此次地震的震源破裂过程.利用海水层地壳模型,剪切位错点源模型的反演结果为:走向323°,倾角86.1°,滑动角-180°,震源深度为10.6km.有限断层模型的反演结果表明,此次地震的破裂过程相对简单,主要滑动量集中于震源上方35km×9km的区域内,破裂时间持续19s左右,平均破裂传播速度约为2.7km·s-1,较大滑动量均沿着走向分布,最大滑动量为249cm.此次地震为发生在戈尔达板块内部的一次Mw6.9级的陡倾角走滑型地震.此次地震为单纯的走滑型地震,断层面接近竖直方向,且发生在洋壳底部,因此破坏力不大,不会对沿岸城市造成重大损失.陡倾角断层在走滑错动的过程中不会使海底地形发生大幅度变化,不会引起大面积水体的突然升降,因此不会诱发大规模海啸. 相似文献
13.
Haijiang Liu Takenori Shimozono Tomohiro Takagawa Akio Okayasu Hermann M. Fritz Shinji Sato Yoshimitsu Tajima 《Pure and Applied Geophysics》2013,170(6-8):1033-1046
On 11 March 2011, a moment magnitude M w = 9.0 earthquake occurred off the Japan Tohoku coast causing catastrophic damage and loss of human lives. In the immediate aftermath of the earthquake, we conducted the reconnaissance survey in the city of Rikuzentakata, Japan. In comparison with three previous historical tsunamis impacting the same region, the 2011 event presented the largest values with respect to the tsunami height, the inundation area and the inundation distance. A representative tsunami height of 15 m was recorded in Rikuzentakata, with increased heights of 20 m around rocky headlands. In terms of the inundation area, the 2011 Tohoku tsunami exceeded by almost 2.6 times the area flooded by the 1960 Chilean tsunami, which ranks second among the four events compared. The maximum tsunami inundation distance was 8.1 km along the Kesen River, exceeding the 1933 Showa and 1960 Chilean tsunami inundations by factors of 6.2 and 2.7, respectively. The overland tsunami inundation distance was less than 2 km. The tsunami inundation height linearly decreased along the Kesen River at a rate of approximately 1 m/km. Nevertheless, the measured inland tsunami heights exhibit significant variations on local and regional scales. A designated “tsunami control forest” planted with a cross-shore width of about 200 m along a 2 km stretch of Rikuzentakata coastline was completely overrun and failed to protect the local community during this extreme event. Similarly, many designated tsunami shelters were too low and were overwashed by tsunami waves, thereby failing to provide shelter for evacuees—a risk that had been underestimated. 相似文献
14.
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. 相似文献
15.
L. Dengler B. Uslu A. Barberopoulou S. C. Yim A. Kelly 《Pure and Applied Geophysics》2009,166(1-2):37-53
On November 15, 2006, Crescent City in Del Norte County, California was hit by a tsunami generated by a M w 8.3 earthquake in the central Kuril Islands. Strong currents that persisted over an eight-hour period damaged floating docks and several boats and caused an estimated $9.2 million in losses. Initial tsunami alert bulletins issued by the West Coast Alaska Tsunami Warning Center (WCATWC) in Palmer, Alaska were cancelled about three and a half hours after the earthquake, nearly five hours before the first surges reached Crescent City. The largest amplitude wave, 1.76-meter peak to trough, was the sixth cycle and arrived over two hours after the first wave. Strong currents estimated at over 10 knots, damaged or destroyed three docks and caused cracks in most of the remaining docks. As a result of the November 15 event, WCATWC changed the definition of Advisory from a region-wide alert bulletin meaning that a potential tsunami is 6 hours or further away to a localized alert that tsunami water heights may approach warning- level thresholds in specific, vulnerable locations like Crescent City. On January 13, 2007 a similar Kuril event occurred and hourly conferences between the warning center and regional weather forecasts were held with a considerable improvement in the flow of information to local coastal jurisdictions. The event highlighted the vulnerability of harbors from a relatively modest tsunami and underscored the need to improve public education regarding the duration of the tsunami hazards, improve dialog between tsunami warning centers and local jurisdictions, and better understand the currents produced by tsunamis in harbors. 相似文献
16.
针对东海冲绳海槽地区的地震地质背景,对东海海域潜在的地震海啸进行了预研究. 假设了冲绳海槽在发生8.5级大地震,断层错距高达15 m的极端地震情况引发的海啸对中国东部沿海地区的影响. 初步数值模拟结果表明,该地震引发的海啸的最大初始波高为4.3 m,4小时左右传至浙江沿岸,近岸各处波高为1——2 m,其中局部地区波高为2.4 m;约7——8小时靠近上海海岸线（若震源在中冲绳海槽地区,海啸传到上海最快大约7小时）,近岸波高约为1 m. 近岸区域地形变化复杂,海岛密布,局部地形条件可能会很大地影响实际各地点海啸波高,加上海啸在岸边爬高及港湾效应,估计波高还会升高. 给出了冲绳海槽南、中、北部发生潜在地震海啸的传播等时图. 笔者在东海设置了3个地震及海啸监测站,基于海啸模拟结果绘制了监测站处的海啸随时间演化曲线,分析了预研究成果对海啸预警可能发挥的作用. 相似文献
17.
S. Allgeyer C. Daubord H. Hébert A. Loevenbruck F. Schindelé R. Madariaga 《Pure and Applied Geophysics》2013,170(9-10):1415-1431
The tsunami generated by the 1 November, 1755 earthquake off the coast of Portugal affected mainly the coastlines of the Iberian Peninsula and Northwest Morocco, but was also observed in some places along the North Atlantic coasts. To determine whether the event could have effected the French coastline, we conducted a study to search for signs of the tsunami in historical records from all tide gauge stations off the French Atlantic coast during the twentieth century, specifically for the 28 February, 1969 and the 26 May, 1975 tsunamis that were recorded by the Portuguese tide gauge network. Because many recordings are available in La Rochelle (located on the southwest coast of France), we focused our study on this harbor. The analysis of the tide gauge data shows no evidence for tsunamis in La Rochelle, neither in 1969 nor in 1975. To confirm this lack of tsunami signals, we used nonlinear, shallow water equations to compute the tsunami propagation to the French Atlantic coastline for both 1969 and 1975 events. Results obtained from these simulations confirm otherwise unnoticeable wave amplitudes at La Rochelle harbor. In a second step, tsunamis from three different scenarios for the 1755 earthquake were modeled to estimate the impact of such a tsunami on the French Atlantic coast, with a focus on La Rochelle harbor. A comparison of the functions of tide configuration was made in order to analyse the difference in impact. The results show that, while the harbor is poorly impacted, several areas (western part of the island of Ré and northern coast of the island of Oléron) may have experienced a moderate impact from 0.5 to 1 m, especially since the tide was high at the time of arrival, possibly causing local inundations in lowland areas. 相似文献
18.
The interpretation of the nature and parameters of the source for the earthquake that occurred in Sumatra on December 26, 2004 is suggested. Our study relies on a variety of data on the geological structure of the region, long-term seismicity, spatial distribution of the foreshocks and aftershocks, and focal mechanisms; and the pattern of shaking and tsunami, regularities in the occurrence of the earthquakes, and the genetic relationship between the seismic and geological parameters inherent in various types of seismogenic zones including island arcs. The source of the Sumatran earthquake is a steep reverse fault striking parallel to the island arc and dipping towards the ocean. The length of the fault is ～450 km, and its probable bedding depth is ～70–100 km. The magnitude of this seismic event corresponding to the length of its source is 8.9–9.0. The vertical displacement in the source probably reached 9–13 m. The fault is located near the inner boundary of the Aceh Depression between the epicenter of the earthquake and the northern tip of the depression. The strike-slip and strike-slip reverse the faults cutting the island arc form the northern and southern borders of the source. The location and source parameters in the suggested interpretation account quite well for the observed pattern of shaking and tsunami. The Aceh Depression and its environs probably also host other seismic sources in the form of large reverse faults. The Sumatran earthquake, which was the culmination of the seismogenic activation of the Andaman-Sumatra island arc in the beginning of XXI century, is a typical tsunamigenic island-arc earthquake. By its characteristics, this event is an analogue to the M W = 9 Kamchatka earthquake of November 4, 1952. The spatial distribution of the epicenters and the focal mechanisms of the aftershocks indicate that the repeated shocks during the Sumatran event were caused by the activation of a complex system of geological structures in various parts of the island arc and Andaman Sea instead of the slips on a single rupture (a subduction thrust about 1200–1300 km in length). 相似文献
19.
2004年12月26日苏门答腊岛安达曼海附近海域发生的9．0级地震和2005年3月28日苏门答腊岛明打威群岛北附近海域的8．7级地震,在构造环境、震级、震源深度、地震类型都相似的情况下,为何前者引发海啸,后者不引发的海啸？对此进行了对比分析,认为9．0级地震发生时,在其震源体附近的两板块相交的海沟两侧陡坡蕴育着滑坡体或和崩塌体（或者两者都有）,9．0级地震发生时,强烈的地震波,促使滑坡体的滑动或崩塌体的崩塌,推压和扰动海水,引发诲啸。而8．7级地震发生时、在其震源体附近的两板块相交的海沟两侧陡坡无滑坡体或和崩塌体,或先存滑坡体或崩塌体在9．0级地震发生时已滑坡或崩塌殆尽,当8.7地震发生时,无滑坡体滑动或崩塌体崩塌,不可能对海水有较大的扰动,故不可能引发海啸。 相似文献
20.
The Mw = 9.3 megathrust earthquake of December 26, 2004 off the northwest coast of Sumatra in the Indian Ocean generated a catastrophic
tsunami that was recorded by a large number of tide gauges throughout the World Ocean. Part 1 of our study of this event examines
tide gauge measurements from the Indian Ocean region, at sites located from a few hundred to several thousand kilometers from
the source area. Statistical characteristics of the tsunami waves, including wave height, duration, and arrival time, are
determined, along with spectral properties of the tsunami records. 相似文献