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1.
The 1963 great Kurile earthquake was an underthrust earthquake occurred in the Kurile?CKamchatka subduction zone. The slip distribution of the 1963 earthquake was estimated using 21 tsunami waveforms recorded at tide gauges along the Pacific and Okhotsk Sea coasts. The extended rupture area was divided into 24 subfaults, and the slip on each subfault was determined by the tsunami waveform inversion. The result shows that the largest slip amount of 2.8?m was found at the shallow part and intermediate depth of the rupture area. Large slip amounts were found at the shallow part of the rupture area. The total seismic moment was estimated to be 3.9?×?1021?Nm (Mw 8.3). The 2006 Kurile earthquake occurred right next to the location of the 1963 earthquake, and no seismic gap exists between the source areas of the 1963 and 2006 earthquakes.  相似文献   

2.
The fault parameters of the Guam earthquake of August 8, 1993 are estimated from seismological analyses, and the possibility of identifying the actual fault plane from tsunami waveforms is tested. The Centroid Moment Tensor solution of long-period surface waves shows one nodal plane shallowly dipping to the north and the other nodal plane steeply dipping to the south. The seismic moment is 3.5×1020 Nm and the corresponding moment magnitude is 7.7. The Moment Tensor Rate Function inversion ofP waves also yields a similar focal mechanism and seismic moment. The point source depth is estimated as 40–50 km.This earthquake generated tsunamis that propagated toward the Japanese coast along the Izu-Bonin-Mariana ridge system. The tsunamis are recorded on ocean bottom pressure gauges and tide gauges. Numerical computation of tsunamis shows that the computed waveforms from the two possible fault planes match well with the observed tsunami waveforms. The numerical computation also shows that the tsunami waveforms at Guam Island, just above the fault, should contain useful information regarding the identification of the actual fault plane. However, the current sampling rate of the tide gauges is so small that the records cannot help the identification.  相似文献   

3.
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.  相似文献   

4.
The M w=9.3 megathrust earthquake of December 26, 2004 off the coast of Sumatra in the Indian Ocean generated a catastrophic tsunami that caused widespread damage in coastal areas and left more than 226,000 people dead or missing. The Sumatra tsunami was accurately recorded by a large number of tide gauges throughout the world's oceans. This paper examines the amplitudes, frequencies and wave train structure of tsunami waves recorded by tide gauges located more than 20,000 km from the source area along the Pacific and Atlantic coasts of North America.  相似文献   

5.
The tsunami in the Indian Ocean caused by the earthquake of December 26, 2004, near Sumatra Island had catastrophic consequences in coastal areas of many countries in this region. Notwithstanding extensive investigations of this phenomenon at various laboratories of the world, the focal mechanism of the aftershock remains unclear. The paper analyzes possible seafloor movements in the source area of the earthquake on the basis of the keyboard model of tsunamigenic earthquakes and describes numerical simulation of the generation, propagation, and runup of water surface waves in terms of this model involving vertical displacements of seafloor “keyboard-blocks.” It is shown that generated tsunami waves are essentially dependent on the combination of keyboard-block movements, which results in an irregular distribution of maximum runups along the shoreline. If the oblique nature of the subduction zone associated with the Sumatra-Andaman earthquake of December 26, 2004, is taken into account, the model results fit well the runup values observed at the Thailand shoreline. It is noted that this model of the subduction zone accounts more adequately for the tsunami wave field pattern in both areas of the Indian Ocean and other water areas such as the region of the Kurile-Kamchatka Island Arc and the Sea of Okhotsk.  相似文献   

6.
Bottom pressure gauges deployed in bays of Shikotan Island (South Kuril Islands) recently recorded two tsunamis: the Simushir (Kuril Islands) tsunami of January 13, 2007 generated by a local earthquake with magnitude M w = 8.1 and the Peruvian tsunami of August 15, 2007 generated by a distant earthquake, M w = 8.0. The records enabled us to investigate the properties of these two tsunamis and to estimate the effect of the regional and nearshore topography on arriving tsunami waves. Eigen periods and spatial structure of resonant oscillations in particular bays were examined based on results of numerical modeling. Significant amplification of the fundamental (Helmholtz) resonant modes in Malokurilskaya Bay (19 min) and in Krabovaya Inlet (29 min) and some secondary modes was caused by the Simushir tsunami. The considerably different geometry and bottom topography of these bays, located on the inner coast of the island, determine the differences in their eigen periods; the only mutual peak, which was found in both basins, had a period of 5 min and was probably related to the source features. The Peruvian tsunami was clearly recorded by the bottom pressure gauge in Tserkovnaya Bay on the outer (oceanic) coast of the island. Three dominant periods in the tsunami spectrum at this bay were 60, 30 and 19 min; the latter period was found to be related to the fundamental mode of the bay, while the other two periods appear to be associated with the shelf resonant amplification of tsunami waves arriving in the region of the South Kuril Islands. The prevalence of low-frequency components in the observed tsunami spectrum is probably associated with the large extension of the initial source area and faster decay of short period waves during the long trans-oceanic tsunami propagation.  相似文献   

7.
We modeled a tsunami from the West Papua, Indonesia earthquakes on January 3, 2009 (M w?=?7.7). After the first earthquake, tsunami alerts were issued in Indonesia and Japan. The tsunami was recorded at many stations located in and around the Pacific Ocean. In particular, at Kushimoto on Kii Peninsula, the maximum amplitude was 43?cm, larger than that at Manokwari on New Guinea Island, near the epicenter. The tsunami was recorded on near-shore wave gauges, offshore GPS sensors and deep-sea bottom pressure sensors. We have collected more than 150 records and used 72 stations?? data with clear tsunami signals for the tsunami source modeling. We assumed two fault models (single fault and five subfaults) which are located to cover the aftershock area. The estimated average slip on the single fault model (80?×?40?km) is 0.64?m, which yields a seismic moment of 1.02?×?1020?Nm (M w?=?7.3). The observed tsunami waveforms at most stations are well explained by this model.  相似文献   

8.
The major (M w = 8.8) Chilean earthquake of 27 February 2010 generated a trans-oceanic tsunami that was observed throughout the Pacific Ocean. Waves associated with this event had features similar to those of the 1960 tsunami generated in the same region by the Great (M w = 9.5) 1960 Chilean Earthquake. Both tsunamis were clearly observed on the coast of British Columbia. The 1960 tsunami was measured by 17 analog pen-and-paper tide gauges, while the 2010 tsunami was measured by 11 modern digital coastal tide gauges, four NEPTUNE-Canada bottom pressure recorders located offshore from southern Vancouver Island, and two nearby open-ocean DART stations. The 2010 records were augmented by data from seven NOAA tide gauges on the coast of Washington State. This study examines the principal characteristics of the waves from the 2010 event (height, period, duration, and arrival and travel times) and compares these properties for the west coast of Canada with corresponding properties of the 1960 tsunami. Results show that the 2010 waves were approximately 3.5 times smaller than the 1960 waves and reached the British Columbia coast 1 h earlier. The maximum 2010 wave heights were observed at Port Alberni (98.4 cm) and Winter Harbour (68.3 cm); the observed periods ranged from 12 min at Port Hardy to 110–120 min at Prince Rupert and Port Alberni and 150 min at Bamfield. The open-ocean records had maximum wave heights of 6–11 cm and typical periods of 7 and 15 min. Coastal and open-ocean tsunami records revealed persistent oscillations that “rang” for 3–4 days. Tsunami energy occupied a broad band of periods from 3 to 300 min. Estimation of the inverse celerity vectors from cross-correlation analysis of the deep-sea tsunami records shows that the tsunami waves underwent refraction as they approached the coast of Vancouver Island with the direction of the incoming waves changing from an initial direction of 340° True to a direction of 15° True for the second train of waves that arrived 7 h later after possible reflection from the Marquesas and Hawaiian islands.  相似文献   

9.
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   

10.
Two remote tsunamis were recorded on the Pacific coast of Russia: a relatively weak Samoan tsunami of September 29, 2009 and a much stronger Chilean tsunami of February 28, 2010. In the area of the South Kuril Islands, records were obtained using autonomous bottom pressure gauges of the Institute of Marine Geology and Geophysics (IMGG). Additionally, for the oceanic coast of the Kamchatka Peninsula, Paramushir, and Bering Islands we used data transmitted from coastal tide gauges of the Russian Tsunami Warning Service (TWS). The maximum trough-to-crest heights of the Samoan tsunami were about 30–40 cm, and were recorded about 3 h after the first tsunami arrival. The maximum Chilean tsunami trough-to-crest wave heights were 218 cm at Severo-Kurilsk, 187 cm at Tserkovnaya Bay (Shikotan Island), and 140 cm at Khodutka Bay (Kamchatka Peninsula). The time between first and maximum waves reached 4 h. Strong sea level oscillations for both events range for a long time: about 15–17 h. The Samoan tsunami induced high-frequency oscillations; a considerable increase in spectral energy in the tsunami spectrum was observed at periods of 4–20 min. In contrast, the Chilean tsunami induced low-frequency oscillations; the dominant periods were 30–80 min. A probable reason for these differences is the different extensions of the source areas (the Chilean source was much larger than the Samoan source) and the different energy radiation directions from the sources. Local topography resonant effects were the main reason of well-expressed peaks in power spectra in different areas: with a period of 10 min (Khodutka Bay), 19–20 min (Malokurilskaya and Tserkovnaya bays), 29 min (Krabovaya Inlet), and 43 min (Avachinskaya Guba and Nikolskoe).  相似文献   

11.
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   

12.
本文假设马尼拉海沟北段为潜在海啸源,基于中国地震台网对马尼拉海沟地区震级测定偏差,采用COMCOT(comell Multi-grid Coupled Tsunami Model)海啸数值模型,模拟南海海啸波传播.选取南海北缘3个特定地点,其中两个位于华南近海区域,另一个位于台湾岛南端近海区域,此外还在临近马尼拉海沟北段的深海地区选取了1个特定地点.分析这些特定地点最大海啸波以及最大海啸波到时对于震级测定偏差的敏感性.结果表明:马尼拉海沟北段地震如触发海啸,华南近海区域以及台湾岛南部近海区域最大海啸波振幅对震级偏差敏感,但最大海啸波振幅到时对于震级测定偏差不敏感;振幅最大的海啸波,二十几分钟即可波及台湾岛南端近岸区域,大约1小时后波及大陆华南近海北部区域.  相似文献   

13.
On the evening of March 28, 2005 at 11:09?p.m. local time (16:09 UTC), a large earthquake occurred offshore of West Sumatra, Indonesia. With a moment magnitude (M w) of 8.6, the event caused substantial shaking damage and land level changes between Simeulue Island in the north and the Batu Islands in the south. The earthquake also generated a tsunami, which was observed throughout the source region as well as on distant tide gauges. While the tsunami was not as extreme as the tsunami of December 26th, 2004, it did cause significant flooding and damage at some locations. The spatial and temporal proximity of the two events led to a unique set of observational data from the earthquake and tsunami as well as insights relevant to tsunami hazard planning and education efforts.  相似文献   

14.
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.  相似文献   

15.
The great Tohoku-oki earthquake of March 11, 2011 generated a devastating tsunami in the near field as well as substantial far-field effects throughout the Pacific Ocean. In New Zealand, the tsunami was widely observed and instrumentally recorded on an extensive array of coastal tidal gauges and supplemented by current velocity data from two sites. While the tsunami's first arrival was on the morning of March 12 in New Zealand, the strongest effects occurred throughout that afternoon and into the following day. Tsunami effects consisted primarily of rapid changes in water level and associated strong currents that affected numerous bays, harbors, tidal inlets and marine facilities, particularly on the northern and eastern shores of the North Island. The tsunami caused moderate damage and significant overland flooding at one location. The tsunami signal was clearly evident on tide gauge recordings for well over 2 days, clearly illustrating the extended duration of far field tsunami hazards. Real time analysis and modelling of the tsunami through the night of March 11, as the tsunami crossed the Pacific, was used as a basis for escalating the predicted threat level for the northern region of New Zealand. A comparison to recorded data following the tsunami shows that these real time prediction models were accurate despite the coarse near-shore bathymetry used in the assessment, suggesting the efficacy of such techniques for future events from far-field sources.  相似文献   

16.
Great differences in hazard and losses were shown from two tsunamis, both generated in Chile, one in 1960 and the other in 2010. Numerical simulation was applied to the tsunami analysis. The fault dislocation of the seafloor was assumed to equal to the initial tsunami wave field, which can be calculated by the formula of fault dislocation in the elastic isotropic half-space. The linear long wave theory was used as the tsunami hydrodynamic model, and the finite difference method and leap-frog scheme were selected for solving the equations. The accuracy of the simulated results was verified by the observed data in five tide gauges. By means of two scenario tsunamis, the analytical results show that the earthquake magnitude, bathymetry in rupture zone and rapid release of warning information in 2010 tsunami are the main explanations of the aforementioned great difference.  相似文献   

17.
Heterogeneous fault motion of the 1993 Hokkaido Nansei-Oki earthquake is studied by using seismic, geodetic and tsunami data, and the tsunami generation from the fault model is examined. Seismological analyses indicate that the focal mechanism of the first 10 s, when about a third of the total moment was released, is different from the overall focal mechanism. A joint inversion of geodetic data on Okushiri Island and the tide gauge records in Japan and Korea indicates that the largest slip, about 6 m, occurred in a small area just south of the epicenter. This corresponds to the initial rupture on a fault plane dipping shallowly to the west. The slip on the northernmost subfault, which is dipping to the east, is about 2 m, while the slips on the southern subfaults, which are steeply dipping to the west, are more than 3 m. Tsunami heights around Okushiri Island are calculated from the heterogeneous fault model using different grid sizes. Computation on the smaller grids produces large tsunami height that are closer to the observed tsunami runup heights. Tsunami propagation in the nearly closed Japan Sea is examined as the free oscillation of the Japan Sea. The excitation of the free oscillation by this earthquake is smaller than that by the 1964 Niigata or 1983 Japan Sea earthquake.  相似文献   

18.
Source model of Noto-Hanto-Oki earthquake tsunami of 7 February 1993   总被引：1，自引：0，他引：1  
A source model was discussed for a small tsunami accompanied by the Noto-Hanto-Oki earthquake (M s 6.6), striking Japan on 7 February, 1994. Assuming a fault model under the sea bottom, we estimated the focal parameters jointly, using synthesized tsunami source spectra as well as the tsunami numerical simulation. The fault proposed by this study consists of a plane sized 15×15 km, dipping N47°W with the dip angle of 42°, which is almost pure reverse fault (slip angle 87°) with a dislocation of 1 meter. The numerical simulation shows that the shallow sea in the source region caused a comparatively long recurring tsunami (the periods are 12–18 minutes) in spite of its small size. The model fault is corresponding to an aftershock area of this earthquake.  相似文献   

19.
The tsunami caused by the 2007 Peru earthquake (Mw 8.0) provoked less damage than by the seismic shaking itself (numerous casualties due to the earthquake in the vicinity of Pisco). However, it propagated across the Pacific Ocean and small waves were observed on one tide gauge in Taiohae Bay (Nuku Hiva, Marquesas, French Polynesia). We invert seismological data to recover the rupture pattern in two steps. The first step uses surface waves to find a solution for the moment tensor, and the second step uses body waves to compute the slip distribution in the source area. We find the slip distribution to consist of two main slip patches in the source area. The inversion of surface waves yields a scalar moment of 8.9 1020 Nm, and body-wave inversion gives 1.4 1021 Nm. The inversion of tsunami data recorded on a single deep ocean sensor also can be used to compute a fault slip pattern (yielding a scalar moment of 1.1 1021 Nm). We then use these different sources to model the tsunami propagation across the Pacific Ocean, especially towards Nuku Hiva. While the source model taken from the body-wave inversion yields computed tsunami waves systematically too low with respect to observations (on the central Pacific Ocean DART buoy as on the Polynesian tide gauge), the source model established from the surface-wave inversion is more efficient to fit the observations, confirming that the tsunami is sensitive to the low frequency component of the source. Finally we also discuss the modeling of the late tsunami arrivals in Taiohae Bay using several friction coefficients for the sea bottom.  相似文献   

20.
We report the statistical and wavelet analyses of the 21 May 2003 tsunami produced by an M w 6.8–6.9 thrust earthquake in the western Mediterranean Sea using 19 tide gauge records. The largest trough-to-crest wave height was 196 cm recorded at the Sant Antoni station in the lee of the incoming tsunami wave. Except at one station, the first wave was not the largest wave at all the analyzed stations, and the largest wave arrived several hours after the first arrival. In addition, the tsunami waves persisted for more than 1 day at most stations. As the spectra of coastal tide gauge stations are strongly influenced by topographic features, special care was taken here while interpreting the results of spectral and wavelet analysis. Our wavelet analysis shows that only a peak at around 23 min is persistent for long duration, and other peaks at 14, 30, 45, and 60 min appeared at short durations. The 23-min signal is possibly associated with the width of the source fault whereas the fault length contributed to the 45-min signal. Based on these dominant periods, the tsunami source dimensions are estimated as 95 km × 45 km. The statistical and wavelet analyses performed here provide some new insights into the characteristics of the tsunami that was generated and propagated in the western Mediterranean basin.  相似文献   

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