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1.
Tsunamis have occurred in Canada due to earthquakes, landslides, and a large chemical explosion. The Pacific coast is at greatest risk from tsunamis because of the high incidence of earthquakes and landslides in that region. The most destructive historical tsunamis, however, have been in Atlantic Canada – one in 1917 in Halifax Harbour, which was triggered by a catastrophic explosion on a munitions ship, and another in 1929 in Newfoundland, caused by an earthquake-triggered landslide at the edge of the Grand Banks. The tsunami risk along Canada's Arctic coast and along the shores of the Great Lakes is low in comparison to that of the Pacific and Atlantic coasts. Public awareness of tsunami hazard and risk in Canada is low because destructive tsunamis are rare events. 相似文献
2.
海啸作为五大海洋自然灾害之一,严重威胁着人类生命财产安全。近些年来,国内外学者对地震海啸进行了大量研究,主要针对海啸的生成、传播、爬高和淹没的数值模拟,以及古海啸沉积物进行研究,但是对于海啸地震震源机制的研究还比较欠缺,尤其是缺乏对震级小于6.5的海啸地震的研究。针对我国的地震海啸研究现状,强调震级小于6.5地震引发海啸的问题不容忽视。本文归纳整理了全球766次地震海啸,利用三角图分类基本法则对海啸地震震源机制解进行分类,并对其中341个发生在1976年后的海啸地震进行震源机制解分析,对其中633次海啸浪高进行统计学方法分析研究。本文认为逆冲型、正断型、走滑型和奇异型机制地震均能引发海啸,逆冲型地震引发的海啸占比最大,震级小于6.5级地震引发的海啸的浪高也有高达10 m的情况,也能产生巨大破坏性。逆冲型、正断型、奇异型地震可直接引起海底地形垂向变化,进而引发海啸,而走滑型地震引发海啸则可能有两种原因,一种是走滑型地震并非纯走滑型而是带有正断或逆冲分量从而引发海啸,另外一种是走滑型地震引发海底滑坡导致海底地形变化进而产生海啸。从海啸地震震源深度分析,能产生海啸的地震震源深度97%以上都是浅源地震,主要集中在30 km深度以内,但是也有中深源地震海啸。本文综合海啸地震的震源特点、我国地理位置以及以往海啸发生的情况,认为未来我国沿海地区威胁性的地震海啸主要集中在马尼拉海沟和台湾海峡区域,在今后海啸预警方面需要格外重视这些区域,通过建立完善海啸预警系统来减少损失。 相似文献
3.
Stefano Tinti 《Natural Hazards》1991,4(2-3):267-283
A method for the evaluation of tsunami potential in the seas surrounding Italy is presented. A major difficulty for performing reliable estimates of tsunami occurrence is that the existing tsunami catalog for Italy includes a small number of cases. This is due partly to the catalog incompleteness, strangely more pronounced in our century, and partly to the relative infrequency of tsunamis along the Italian seas. Evaluation of tsunami activity is therefore deduced by complementing the tsunami catalog data with data on seismicity that are by far more abundant and reliable. Analysis of seismicity and assessment of earthquake rate in coastal and submarine regions form the basis of the present method to perform tsunami potential estimates for Italy. One essential limitation of the method is that only tsunamis of seismic origin are taken into account, which leads to an underestimation of the tsunami potential. Since tsunamis generated by earthquakes are much more frequent than events produced by slumps or volcanic eruptions, the underestimation is not dramatic and very likely affects only a limited portion of the Italian coasts. In the present application of the method, eight separate regions have been considered that together cover all the coasts of Italy. In each region, seismicity has been independently examined and the earthquake potential has been calculated in small 20 × 20 cells. Then, on the basis of suitable assumptions, tsunami potential has been evaluated in each cell. According to this study, the Italian coasts that are the most exposed to the attacks of locally generated tsunamis are to be found in the Messina Straits, in Tyrrhenian coasts of Calabria, in the Ionian Sicilian coasts around Catania, and in the Gargano promontory in the Southern Adriatic Sea. Furthermore, this study confirms that the Northern Adriatic Sea has a low level of tsunami potential, in agreement with recent studies emphasizing that the large historical events concerning this region included in the first versions of the Italian tsunami catalog are largely overestimated and must be decreased. 相似文献
4.
A tsunami catalogue for Central America is compiledcontaining 49 tsunamis for the period 1539–1996,thirty seven of them are in the Pacific and twelve inthe Caribbean. The number of known tsunamis increaseddramatically after the middle of the nineteenth century,since 43 events occurred between 1850 and 1996. This isprobably a consequence of the lack of populationliving near the coast in earlier times.The preliminary regionalization of the earthquakessources related to reported tsunamis shows that, inthe Pacific, most events were generated by theCocos-Caribbean Subduction Zone (CO-CA). At theCaribbean side, 5 events are related with the NorthAmerican-Caribbean Plate Boundary (NA-CA) and 7 withthe North Panama Deformed Belt (NPDB).There are ten local tsunamis with a specific damagereport, seven in the Pacific and the rest in theCaribbean. The total number of casualties due to localtsunamis is less than 455 but this number could behigher. The damages reported range from coastal andship damage to destruction of small towns, and theredoes not exist a quantification of them.A preliminary empirical estimation of tsunami hazardindicates that 43% of the large earthquakes (Ms 7.0) along the Pacific Coast of Central America and100% along the Caribbean, generate tsunamis. On thePacific, the Guatemala–Nicaragua coastal segment hasa 32% probability of generating tsunamis after largeearthquakes while the probability is 67% for theCosta Rica–Panama segment. Sixty population centers onthe Pacific Coast and 44 on the Caribbean are exposedto the impact of tsunamis. This estimation alsosuggests that areas with higher tsunami potential inthe Pacific are the coasts from Nicaragua to Guatemalaand Central Costa Rica; on the Caribbean side, Golfode Honduras Zone and the coasts of Panama and CostaRica have major hazard. Earthquakes of magnitudelarger than 7 with epicenters offshore or onshore(close to the coastline) could trigger tsunamis thatwould impact those zones. 相似文献
5.
A modern tsunami catalogue has been compiled for the region of Cyprus-Levantine Sea in which 24 certain or possible local
tsunamis are listed from antiquity up to the present time, while six regional tsunamis, generated in the Hellenic arc, are
documented which affected the region. Another set of 13 doubtful events not included in the catalogue are discussed. Tsunami
intensities k and K were re-evaluated using the classic 6-grade and the new 12-grade intensity scales, respectively. The strongest tsunamis reported
in the region of interest are those of 551 AD, 749, 1068, 1201, 1222, 1546 and 1759, all occurring along the Levantine coast
from Gaza northward, with the exception of the 1222 wave which occurred in the Cyprean arc. The causative earthquakes, however,
occur on land and are associated with the left-lateral strike-slip Levantine rift and, as such, remain unexplained. In this
paper we speculate on the mechanism of these events. A second tsunami zone follows the Cyprean arc, where the situation of
subaqueous seismogenic sources favours the generation of tsunamis by co-seismic fault displacements. Submarine or coastal
earth slumping, however, may be an additional tsunamigenic component. Based on historical data, the average tsunami recurrence
in the Cyprus-Levantine Sea region is roughly estimated to be around 30 years, 120 years and 375 years for moderate (k/K ≥ 2/3), strong (k/K ≥ 3/5) and very strong (k/K ≥ 5/8) events, respectively. The rate of tsunami occurrence equals 0.033, 8.3 × 10−3 and 2.7 × 10−3 events/year for intensity k/K ≥ 2/3, 3/5 and 5/8, respectively. For a Poissonian (random) process the probabilities of observing at least one moderate,
strong or very strong tsunami are 0.28, 0.01 and 3 × 10−3 within 1 year, 0.81, 0.34 and 0.13 within 50 years and 0.96, 0.56 and 0.24 within 100 years, respectively. The tsunami potential
in the Cyprus-Levantine Sea area is low relative to other Mediterranean tsunamigenic regions. However, the destructiveness
of some historical events indicates the need to evaluate tsunami hazard by all available means. In addition, remote tsunamigenic
sources, such as those of 1303 and 1481 in the eastern Hellenic arc, are able to threaten the coasts of the Cyprus-Levantine
region and, therefore, such regional tsunamis should be taken into account in the evaluation of the tsunami risk of the region. 相似文献
6.
Tokutaro Hatori 《GeoJournal》1996,38(3):313-319
The regional characteristics of tsunami magnitudes in the SE Asia region are discussed in relation to earthquake magnitudes during the period from 1960 to 1994. Tsunami magnitudes on the Imamura-Iida scale are investigated by the author's method (Hatori 1979, 1986) using the data of inundation heights near the source area and tide-gauge records observed in Japan. The magnitude values of the Taiwan tsunamis showed relatively to be small. On the contrary, the magnitudes of tsunamis in the vicinities of the Philippines and Indonesia exceed more than 1–2 grade (tsunami heights: 2–5 times) compared to earthquakes with similar size on the circum-Pacific zone. The relation between tsunami magnitude, m, and earthquake magnitude, M
s, is expressed as m = 2.66 M
s– 17.5 for these regions. For example, the magnitudes for the 1976 Mindanao tsunami (M
s= 7.8, 3702 deaths) and the 1992 Flores tsunami (M
s= 7.5, 1713 deaths) were determined to be m = 3 and m = 2.5, respectively. The focal depth of tsunamigenic earthquakes is shallower thand< 36 km, and the detectively of tsunamis is small for deep earthquakes being d > 40 km. For future tsunamis, it is indispensable to take precautions against shallow earthquakes having the magnitudes M
s> 6.5. 相似文献
7.
The major earthquake-induced tsunamis reliable known to have occurred in and near Greece since antiquity are considered in the light of the recently obtained reliable data on the mechanisms and focal depths of the earthquakes occurring here. (The earthquake data concern the major shocks of the period 1962–1986.) First, concise information is given on the most devastating tsunamis. Then the relation between the (estimated) maximum tsunami intensity and the earthquake parameters (mechanism and focal depth) is examined. It is revealed that the most devastating tsunamis took place in areas (such as the western part of the Corinthiakos Gulf, the Maliakos Gulf, and the southern Aegean Sea) where earthquakes are due to shallow normal faulting. Other major tsunamis were nucleated along the convex side of the Hellenic arc, characterized by shallow thrust earthquakes. It is probably somewhere there (most likely south of Crete) that the region's largest known tsunami occurred in AD 365, claiming many lives and causing extensive devastation in the entire eastern Mediterranean. Such big tsunamis seem to have a return period of well over 1000 years and can be generated by large shallow earthquakes associated with thrust faulting beneath the Hellenic trench, where the African plate subduces under the Euroasian plate. Lesser tsunamis are known in the northernmost part of the Aegean Sea and in the Sea of Marmara, where strike-slip faulting is observed. Finally, an attempt is made to combine the tsunami and earthquake data into a map of the region's main tsunamigenic zones (areas of the sea bed believed responsible for past tsunamis and expected to nucleate tsunamis in the future). 相似文献
8.
We present the results of work on the compilation of a fuller and more comprehensive historical catalogue of earthquakes and tsunamis in the basin of the Black Sea and the Sea of Azov, an area of primary importance for the Russian Federation. In the 20th century, there were no significant tsunamis in the Black Sea; therefore, its coast was not considered tsunami-prone. A systematic search for new data sources, a revision of earlier ones, and the use of new approaches to the identification of tsunamigenic events resulted in a more than doubling of the number of known tsunamigenic events in this basin, bringing it up to 50. The total length of the new tsunami catalogue reached 3000 years, which makes it the second longest after the Mediterranean tsunami catalogue (about 4000 years). Taking into account the seismotectonic features of the Black Sea region, we processed data on historical tsunamis and analyzed the geographical and temporal distributions of their sources. For all tsunamigenic events we performed a parameterization of available information about their sources and coastal manifestations, evaluated the tsunami intensity based on the Soloviev-Imamura scale, and proposed a classification of tsunami and tsunami-like water wave disturbances based on their genesis. Tsunami run-up heights, inland penetration, and damage were estimated with regard for the newly found data. Among the identified historical events, there are devastating tsunamis with run-ups of 4-5 m, sometimes up to 6-8 m, which resulted in disastrous consequences for several ancient cities (Dioscuria, Sebastopolis, Bizone, and Panticapaeum) and many coastal settlements. Expert assessments of the most tsunami-prone areas of the coasts are given. 相似文献
9.
The largest uncertainty in assessing hazards from local tsunamis along the Cascadia margin is estimating the possible earthquake source parameters. We investigate which source parameters exert the largest influence on tsunami generation and determine how each parameter affects the amplitude of the local tsunami. The following source parameters were analyzed: (1) type of faulting characteristic of the Cascadia subduction zone, (2) amount of slip during rupture, (3) slip orientation, (4) duration of rupture, (5) physical properties of the accretionary wedge, and (6) influence of secondary faulting. The effect of each of these source parameters on the quasi-static displacement of the ocean floor is determined by using elastic three-dimensional, finite-element models. The propagation of the resulting tsunami is modeled both near the coastline using the two-dimensional (x-t) Peregrine equations that includes the effects of dispersion and near the source using the three-dimensional (x-y-t) linear long-wave equations. The source parameters that have the largest influence on local tsunami excitation are the shallowness of rupture and the amount of slip. In addition, the orientation of slip has a large effect on the directivity of the tsunami, especially for shallow dipping faults, which consequently has a direct influence on the length of coastline inundated by the tsunami. Duration of rupture, physical properties of the accretionary wedge, and secondary faulting all affect the excitation of tsunamis but to a lesser extent than the shallowness of rupture and the amount and orientation of slip. Assessment of the severity of the local tsunami hazard should take into account that relatively large tsunamis can be generated from anomalous tsunami earthquakes that rupture within the accretionary wedge in comparison to interplate thrust earthquakes of similar magnitude. 相似文献
10.
A probabilistic tsunami hazard assessment for the Makran subduction zone at the northwestern Indian Ocean 总被引：2，自引：1，他引：1
A probabilistic tsunami hazard assessment is performed for the Makran subduction zone (MSZ) at the northwestern Indian Ocean
employing a combination of probability evaluation of offshore earthquake occurrence and numerical modeling of resulting tsunamis.
In our method, we extend the Kijko and Sellevoll’s (1992) probabilistic analysis from earthquakes to tsunamis. The results suggest that the southern coasts of Iran and Pakistan,
as well as Muscat, Oman are the most vulnerable areas among those studied. The probability of having tsunami waves exceeding
5 m over a 50-year period in these coasts is estimated as 17.5%. For moderate tsunamis, this probability is estimated as high
as 45%. We recommend the application of this method as a fresh approach for doing probabilistic hazard assessment for tsunamis.
Finally, we emphasize that given the lack of sufficient information on the mechanism of large earthquake generation in the
MSZ, and inadequate data on Makran’s paleo and historical earthquakes, this study can be regarded as the first generation
of PTHA for this region and more studies should be done in the future. 相似文献
11.
Preliminary estimation of the tsunami hazards associated with the Makran subduction zone at the northwestern Indian Ocean 总被引：3，自引：3，他引：0
Mohammad Heidarzadeh Moharram D. Pirooz Nasser H. Zaker Ahmet C. Yalciner 《Natural Hazards》2009,48(2):229-243
We present a preliminary estimation of tsunami hazard associated with the Makran subduction zone (MSZ) at the northwestern
Indian Ocean. Makran is one of the two main tsunamigenic zones in the Indian Ocean, which has produced some tsunamis in the
past. Northwestern Indian Ocean remains one of the least studied regions in the world in terms of tsunami hazard assessment.
Hence, a scenario-based method is employed to provide an estimation of tsunami hazard in this region for the first time. The
numerical modeling of tsunami is verified using historical observations of the 1945 Makran tsunami. Then, a number of tsunamis
each resulting from a 1945-type earthquake (M
w 8.1) and spaced evenly along the MSZ are simulated. The results indicate that by moving a 1945-type earthquake along the
MSZ, the southern coasts of Iran and Pakistan will experience the largest waves with heights of between 5 and 7 m, depending
on the location of the source. The tsunami will reach a height of about 5 m and 2 m in northern coast of Oman and eastern
coast of the United Arab Emirates, respectively. 相似文献
12.
中国东海、南海等近海临近琉球海沟、马尼拉海沟等俯冲带,地震频发。过去的海啸研究主要关注历史文献分析、海啸数值模拟等,据此评估中国近岸海啸灾害的历史和风险。历史时期是否引发了海啸,特别是具有特大致灾风险的大海啸记录,目前还不明确。近年来,本课题组通过对海岛、海洋沉积和海岸带及其岛屿的沉积过程、海啸遗迹和历史记录研究,阐述了确定古海啸的系列研究方法。首先通过对南海西沙群岛东岛湖泊沉积序列、大量砗磲和珊瑚块在海岛分布的特征分析,识别出距今千年的一次海啸事件。以此为标志,根据湖泊沉积结构作为识别海岛海啸沉积的特征。同时提出了确定海岛海啸发生时代的样品采集和定年方法,其中包括根据事件沉积层顶部和底部植物残体14C年龄定年和历史文献记录的印证。首次确定在过去1 300年中,南海发生过一次海啸,其发生时间为公元1076年。为了寻找更古老的海啸记录,结合对东海闽浙沿岸过去两千年海洋泥质沉积的分析,发现南海海啸在沉积序列中留下记录,但除此之外沉积记录中并无更强的扰动,因此东海在过去两千年中受到海啸的影响较小。1076年的海啸同时冲击了南海沿岸,通过对广东南澳岛考察发现,岛屿东南海岸保存着距今约1 000年的海啸沉积层,其中夹杂着宋代陶器瓷器残片。对遗迹数量变化的分析显示,岛上的文化受海啸破坏出现了长达500年的文化中断,直至明代中后期设镇之后才逐渐恢复。根据海啸层植物残体、贝壳14C测年、覆盖海啸层的海砂光释光定年以及瓷器碎片的年代鉴定了海啸的发生时代,并据此提出了海岸带古海啸沉积的定年方法。此外,不同环境下海啸沉积的特征也存在较大区别,需要结合地形、沉积物来源以及地球化学特征等多种指标进行识别。有迹象表明海南岛东侧海岸带有海啸破坏的明显证据,需要进行深入的研究。 相似文献
13.
George Pararas-Carayannis 《Natural Hazards》1988,1(3):285-294
The major earthquake measuring 8.1 on the Richter scale which struck the west coast of Mexico on Thursday 19 September 1985, generated a small tsunami. A major aftershock on 21 September, with a magnitude of 7.5 also produced a small tsunami. Both tsunamis propagated across the Pacific and were recorded by several tide stations in Central America, Colombia, Ecuador, French Polynesia, Samoa, and Hawaii. No reports of damage were received from any of the stations, and only minor damage due to the first tsunami was reported from the source region.A survey was made by the International Tsunami Information Center (ITIC) of the coastal area affected, from Manzanillo to Zihuatanejo. Tsunami runup measurements were taken and interviews with local residents in the coastal areas were conducted.A source mechanism study of the tsunamis was undertaken using seismic and geologic data and empirical relationships. Earthquake and tsunami energies were estimated and the tsunami genertion areas defined.The earthquake energies were estimated to be 5.61 × 1024 erg for the 19 September event and 9.9 × 1023 erg for the 21 September event. Tsunami energies were estimated to be 0.7 × 1020 erg for the first event and 0.56 × 1020 erg for the second event. The source area of the first tsunami was determined to be approximately one-half of the earthquake source area, or approximately 7500 km2, while the source area of the second tsunami was estimated to be equal to the earthquake area.The relatively small tsunamis generated by these large earthquakes are attributed to the shallow angle of subduction of the Cocos plate underneath the North American plate for this particular region, and to the small vertical component of crustal displacements. However, the angle of subduction increases further south and local earthquakes from that area have the potential of producing large tsunamis on the west coast of Mexico.This paper was presented at the 4th International Symposium on Natural and Man-made Coastal Hazards held in Ensenada, Mexico, August 1988. 相似文献
14.
Babloo Chaudhary Hemanta Hazarika Akira Murakami Kazunori Fujisawa 《Acta Geotechnica》2018,13(4):997-1017
Many breakwaters have collapsed in the past due to earthquakes and subsequent tsunamis, resulting in considerable devastation as the breakwaters failed to prevent the tsunami from entering the coastal plain areas. Breakwater failures are mainly caused by damage to its foundation ground. However, the damage mechanism of breakwater foundation during earthquakes and tsunamis remains unclear. This study focuses on the breakwater failure mechanism due to collapse of its foundation under the action of an earthquake and subsequent tsunami. In addition, reinforcing countermeasures for breakwater foundation to mitigate damage due to compound geodisasters triggered by earthquakes and tsunamis are proposed. Sheet piles and gabions were used in the breakwater foundation as reinforcing countermeasures. To evaluate the effectiveness of the reinforced foundation, a series of shaking table tests and hydraulic model tests were performed. The tsunami overflow tests were conducted on the same model after the earthquake loadings, and comparisons were made between the conventional and reinforced foundations. It was observed during the tests that the reinforced foundation could effectively reduce the damage to the breakwater caused by earthquake and tsunami-induced forces. Numerical analyses were performed to clarify the mechanism of the soil–breakwater–reinforcement–fluid system. Overall, this study is useful in practical engineering, and the reinforcing foundation model could be adopted for offshore structures to reduce damage from earthquakes and tsunamis in the future. 相似文献
15.
Amirhomayoun Saffarzadeh Takayuki Shimaoka Hirofumi Nakayama Takao Hanashima Kentaro Yamaguchi Kazutoshi Manabe 《Natural Hazards》2017,88(3):1273-1295
The potential impacts of tsunamis along the Catalan Coast (NW Mediterranean) are analysed using numerical modelling. The region is characterized by moderate to low seismic activity and by moderate- to low-magnitude earthquakes. However, the occurrence of historical strong earthquakes and the location of several active offshore faults in front of the coast suggest that the possibility of an earthquake-triggered tsunami is not negligible although of low probability. Up to five faults have been identified to generate tsunamis, being the highest associated possible seismic magnitudes of up to 7.6. Coastal flooding and port agitation are characterized using the Worst-case Credible Tsunami Scenario Analysis approach. The results show a multiple fault source contribution to tsunami hazard. The shelf dimensions and the existence of submerged canyons control the tsunami propagation. In wide shelves, waves travelling offshore may become trapped by refraction causing the wave energy to reach the coastline at some distance from the origin. The free surface water elevation increases at the head of the canyons due to the sharp depth gradients. The effects of potential tsunamis would be very harmful in low-lying coastal stretches, such as deltas, with a high population concentration, assets and infrastructures. The Ebro delta appears to be the most exposed coast, and about the 20% of the delta surface is prone to flooding due to its extremely low-lying nature. The activity at Barcelona port will be severely affected by inflow backflow current at the entrance of up to 2 m/s. 相似文献
16.
David R. Tappin 《Geology Today》2017,33(5):190-200
Most tsunamis are generated by earthquakes, with secondary, less frequent, mechanisms including subaerial and submarine landslides, volcanic eruptions and (extra‐terrestrial) bolide impacts. Different mechanisms generate tsunamis with different magnitudes, travel distances and impacts. Submarine landslides had been mapped and studied for decades but records suggested that only a few had generated tsunamis, and that these were minor. It was not until 1998, when a slump on the seabed offshore of northern Papua New Guinea caused a tsunami wave up to 15 m high that killed over 2200 people, was the significance of submarine landslides in tsunami generation realised. A combination of new (multibeam) seabed mapping technology and the development of improved numerical tsunami models for tsunami generation led to the recognition of the landslide tsunami mechanism of the PNG event. As a result the hazard from submarine landslides in tsunami generation is now recognized and better understood. Extensive mapping of ocean margins reveals that submarine landslides are common. Although many of these probably generated tsunamis, few have been identified, so their hazard remains uncertain. This article describes how the hazard from submarine landslide tsunamis was first recognized, how submarine landslides generate tsunamis, why they were previously discounted as a major hazard, and their potential hazards. An important aspect of the recognition of the tsunami hazard from submarine landslides has been the significance of geology, which has contributed to a subject previously dominated by seismologists. 相似文献
17.
Silvia E. Chacón-Barrantes Marino Protti 《Journal of South American Earth Sciences》2011,31(4):372-382
Although subduction zones around the world are known to be the source of earthquakes and/or tsunamis, not all segments of these plate boundaries generate destructive earthquakes and catastrophic tsunamis. Costa Rica, in Central America, has subduction zones on both the Pacific and the Caribbean coasts and, even though large earthquakes (Mw = 7.4–7.8) occur in these convergent margins, they do not produce destructive tsunamis. The reason for this is that the seismogenic zones of the segments of the subduction zones that produce large earthquakes in Costa Rica are located beneath land (Nicoya peninsula, Osa peninsula and south of Limón) and not off shore as in most subduction zones around the world. To illustrate this particularity of Costa Rican subduction zones, we show in this work the case for the largest rupture area in Costa Rica (under the Nicoya peninsula), capable of producing Mw ～ 7.8 earthquakes, but the tsunamis it triggers are small and present little potential for damage even to the largest port city in Costa Rica.The Nicoya seismic gap, in NW Costa Rica, has passed its ～50-year interseismic period and therefore a large earthquake will have to occur there in the near future. The last large earthquake, in 1950 generated a tsunami which slightly affected the southwest coast of the Nicoya Peninsula. We present here a simulation to study the possible consequences that a tsunami generated by the next Nicoya earthquake could have for the city of Puntarenas. Puntarenas has a population of approximately eleven thousand people and is located on a 7.5 km long sand bar with a maximum height of 2 m above the mean sea level. This condition makes Puntarenas vulnerable to tsunamis. 相似文献
18.
S. L. Soloviev 《Natural Hazards》1990,3(2):183-202
A list of 300 tsunamis and similar phenomena known in the Mediterranean is given. Data reliability and wave intensity are estimated; mechanisms of tsunami generation are indicated and data from literature sources on the coordinates and magnitudes of tsunamigenic earthquakes are cited. Eighteen zones of excitation and manifestation of tsunamis are identified which can be integrated into four groups with respect to the recurrence period and maximum intensity of the tsunamis. The strongest tsunamis are excited in the Aegean Sea, and the Hellenic and Calabrian island arcs. The focal depth of the earthquake-generating tsunamis in the Mediterranean is, on average, less than that in the Pacific. Correspondingly, the magnitude of tsunamigenic earthquakes is lower. According to preliminary estimates, the Mediterranean tsunamis attenuate with distance more rapidly than do those in the Pacific Ocean. 相似文献
19.
The 2011 Tohoku earthquake and tsunami motivated an analysis of the potential for great tsunamis in Hawai‘i that significantly exceed the historical record. The largest potential tsunamis that may impact the state from distant, Mw 9 earthquakes—as forecast by two independent tsunami models—originate in the Eastern Aleutian Islands. This analysis is the basis for creating an extreme tsunami evacuation zone, updating prior zones based only on historical tsunami inundation. We first validate the methodology by corroborating that the largest historical tsunami in 1946 is consistent with the seismologically determined earthquake source and observed historical tsunami amplitudes in Hawai‘i. Using prior source characteristics of Mw 9 earthquakes (fault area, slip, and distribution), we analyze parametrically the range of Aleutian–Alaska earthquake sources that produce the most extreme tsunami events in Hawai‘i. Key findings include: (1) An Mw 8.6 ± 0.1 1946 Aleutian earthquake source fits Hawai‘i tsunami run-up/inundation observations, (2) for the 40 scenarios considered here, maximal tsunami inundations everywhere in the Hawaiian Islands cannot be generated by a single large earthquake, (3) depending on location, the largest inundations may occur for either earthquakes with the largest slip at the trench, or those with broad faulting over an extended area, (4) these extremes are shown to correlate with the frequency content (wavelength) of the tsunami, (5) highly variable slip along the fault strike has only a minor influence on inundation at these tele-tsunami distances, and (6) for a given maximum average fault slip, increasing the fault area does not generally produce greater run-up, as the additional wave energy enhances longer wavelengths, with a modest effect on inundation. 相似文献
20.
Patricia A. Lockridge 《Natural Hazards》1990,3(4):403-412
While earthquakes generate about 90% of all tsunamis, volcanic activity, landslides, explosions, and other nonseismic phenomena can also result in tsunamis. There have been 53 000 reported deaths as a result of tsunamis generated by landslides and volcanoes. No death tolls are available for many events, but reports indicate that villages, islands, and even entire civilizations have disappeared. Some of the highest tsunami wave heights ever observed were produced by landslides. In the National Geophysical Data Center world-wide tsunami database, there are nearly 200 tsunami events in which nonseismic phenomena played a major role. In this paper, we briefly discuss a variety of nonseismic phenomena that can result in tsunamis. We discuss the magnitude of the disasters that have resulted from such events, and we discuss the potential for reducing such disasters by education and warning systems. 相似文献