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1.
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
2.
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
3.
A Probabilistic Tsunami Hazard Assessment for Western Australia 总被引：2，自引：0，他引：2
David Burbidge Phil R. Cummins Richard Mleczko Hong Kie Thio 《Pure and Applied Geophysics》2008,165(11-12):2059-2088
The occurrence of the Indian Ocean Tsunami on 26 December, 2004 has raised concern about the difficulty in determining appropriate tsunami mitigation measures in Australia, due to the lack of information on the tsunami threat. A first step in the development of such measures is a tsunami hazard assessment, which gives an indication of which areas of coastline are most likely to experience tsunamis, and how likely such events are. Here we present the results of a probabilistic tsunami hazard assessment for Western Australia (WA). Compared to other parts of Australia, the WA coastline experiences a relatively high frequency of tsunami occurrence. This hazard is due to earthquakes along the Sunda Arc, south of Indonesia. Our work shows that large earthquakes offshore of Java and Sumba are likely to be a greater threat to WA than those offshore of Sumatra or elsewhere in Indonesia. A magnitude 9 earthquake offshore of the Indonesian islands of Java or Sumba has the potential to significantly impact a large part of the West Australian coastline. The level of hazard varies along the coast, but is highest along the coast from Carnarvon to Dampier. Tsunamis generated by other sources (e.g., large intra-plate events, volcanoes, landslides and asteroids) were not considered in this study. 相似文献
4.
The integral characteristics of source geometry, source duration, and rupture propagation for the Sumatra-Andaman earthquake of December 26, 2004 and for the March 28, 2005 earthquake near northern Sumatra have been determined. The source parameters were found by analyzing records of the higher orbits of long-period surface waves. The results are compared with the large-scale average characteristics of tomographic models for the source process based on different data sets that diverge in some details, as well as with the aftershock distribution for the considered earthquakes. 相似文献
5.
An interpretation of the parameters of earthquake sources is proposed for the two large earthquakes in the Rat Islands of February 4, 1965 (M W = 8.7), and November 17, 2003 (M W = 7.7–7.8), based on the analysis of focal mechanisms, the manifestation of aftershocks, and the specific features of the geological structure of the island slope of the Rat Islands. The source of the earthquake of 1965 is a reverse fault of longitudinal strike, with a length of ～350 km. It is located in the lower part of the Aleutian Terrace and probably is genetically connected with the development of the Rat submarine ridge. The westward boundary of the earthquake source is determined by the Heck Canyon structures, and the eastward boundary is determined by the end of Rat Ridge in the region of λ ～ 179°E–179.5°E. The source of the earthquake of 2003 is a steep E-W reverse fault extending for about 100 km. It is located in the eastern part of the Rat Islands, higher on the slope than the source of the earthquake of 1965. The westward end of the earthquake source is determined by Rat Canyon structures, and the eastward end is an abrupt change in isobaths in the region of λ ～ 179°E. According to the aftershock hypocenters, the depth of occurrence of the reverse fault could reach ～60 km. According to our interpretation, on the southern slope of the Rat and Near islands, there is a complex system of seismogenic faults that is caused by tectonic development of different structural elements. The dominant types of faults here are reverse faults, as in other island arcs. During earthquakes, reverse faults oriented along the island arc and also faults that intersect it exhibit themselves. The reverse faults of northeastern strike that intersect the arc characterize the type of tectonic motions in a series of canyons of the western part of the Aleutian Islands. 相似文献
6.
L. M. Balakina 《Izvestiya Physics of the Solid Earth》2011,47(9):835-846
The paper addresses the interpretation of the location, type, and size of the source for the earth-quake of March 11, 2011.
The source—a subvertical reverse fault trending in the azimuth of ∼25° along the island arc—is located in the middle part
of the Pacific slope of Honshu Island, between 38°–38.5°N and 35.5°N. The length of the source, about 350 km, approximately
corresponds to a magnitude ∼8.7 earthquake. In the north, the source is bounded by a sublatitudinal reverse fault, which generated
an earthquake with magnitude 7.2–7.5 in 1978. On this segment of the Pacific slope of Honshu Island, there are probably another
one or a few other large seismic sources, which are still latent. They are longitudinal reverse faults, which are comparable
in scale with the source of the March, 2011 earthquake. The recurrence period of the maximal earthquakes in such sources is
more than 1000 years. 相似文献
7.
Alexander B. Rabinovich Richard E. Thomson Fred E. Stephenson 《Surveys in Geophysics》2006,27(6):647-677
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
8.
In this study, a scheme to estimate oceanic and hydrological effects in the GRACE (Gravity Recovery and Climate Experiment) data is presented. The aim is to reveal tectonic signals for the case of the Sumatra earthquake on 26 December 2004. The variations of hydrological and oceanic effects are estimated with the aid of data set of GRACE, altimetry, World Ocean Atlas, and the GLDAS model for a period of January 2003 to December 2006. The time series of computed gravity changes over Sumatra region show some correlations to the deformation resulting from the earthquake occurred in December 2004. The maximum and minimum impacts of hydrological and oceanic effects on gravity changes are about 3 μGal in radial direction and–5 μGal in northward direction. The maximum and minimum amounts of gravitational gradient changes after the correction are 0.2 and–0.25 mE, which indicates the significant influences of hydrological and oceanic sources on the desired signal. 相似文献
9.
Andaman-Sumatra island arc: 1. Spatiotemporal manifestations and focal mechanisms of the earthquakes 总被引：1，自引：0，他引：1
The spatiotemporal manifestations of seismicity in the Andaman-Sumatra island arc are studied using the instrumental data
for 1900–2010. The data on the largest tsunamigenic earthquakes of the 18th–19th centuries were also taken into account. The
epicenters of the earthquakes are established to cluster in some areas; their possible relation to the structural features
of the island arc is considered. A distinctive feature of seismicity in the region of the Andaman Sea is the presence of compact
swarms of numerous earthquakes occurring during short intervals of time. The distribution of the earthquakes by the depth
of their hypocenters in different segments of the island arc is investigated. The focal mechanisms of the earthquakes are
analyzed using the centroid-moment-tensor (CMT) determinations over the period of 1980–2004, and the characteristic features
of their parameters in different segments of the Andaman-Sumatra island arc are formulated. The focal parameters of the earthquakes
determined by CMT and the moment-tensor-solution (MTS) are compared; the possible uncertainty in the estimates of the focal
mechanisms is assessed. The pattern of the spatiotemporal manifestations of the Andaman-Sumatra earthquakes and their focal
mechanisms are compared to the data on the Kuril-Kamchatka and the Aleutian island arcs previously studied by the authors.
The results of analyzing the long-term seismicity and focal mechanisms in the Andaman-Sumatra island arc provide a necessary
basis for the further thorough investigation of the geological conditions and source parameters of the major Sumatra earthquakes
of 2000–2010. 相似文献
10.
Energy Decay of the 2004 Sumatra Tsunami in the World Ocean 总被引：1，自引：0，他引：1
Alexander B. Rabinovich Rogério N. Candella Richard E. Thomson 《Pure and Applied Geophysics》2011,168(11):1919-1950
The catastrophic Indian Ocean tsunami generated off the coast of Sumatra on 26 December 2004 was recorded by a large number
of tide gauges throughout the World Ocean. This study uses gauge records from 173 sites to examine the characteristics and
energy decay of the tsunami waves from this event in the Indian, Atlantic and Pacific oceans. Findings reveal that the decay
(e-folding) time of the tsunami wave energy within a given oceanic basin is not uniform, as previously reported, but depends
on the absorption characteristics of the shelf adjacent to the coastal observation site and the time for the waves to reach
the site from the source region. In general, the decay times for island and open-ocean bottom stations are found to be shorter
than for coastal mainland stations. Decay times for the 2004 Sumatra tsunami ranged from about 13 h for islands in the Indian
Ocean to 40–45 h for mainland stations in the North Pacific. 相似文献
11.
2004年12月26日印尼苏门答腊Mw9.3特大地震的发生,对全球气候和地震趋势都将产生重大影响.本文讨论了2004年印尼苏门答腊Mw9.3特大地震、2005南亚克什米尔M7.8大震以及2001年中国昆仑山M8.1大震之间的相互关系.同时指出,2006～2007年中国大陆西部地区有可能发生7级左右强震. 相似文献
12.
Cvetan Sinadinovski 《Bulletin of Earthquake Engineering》2006,4(2):131-139
A great earthquake occurred at 00:58:49 (UTC) on Sunday, December 26, 2004 off the northwest coast of Sumatra, Indonesia. Its revised moment magnitude was M 9.3 making it in the top four largest earthquakes in the world since 1900 and the largest since the Alaskan 1964 event. The earthquake caused tsunami waves which killed more than 300,000 people in Southern Asia and Africa. There were 31 earthquakes with magnitudes between 5.5 and 7.3 in the 48-h period after the main event, and it seemed that seismicity migrated northwards along the 1200 km fault (http: //www.ga.gov.au). Similar size events occurred in that location off Sumatra in the 19th century, but no evidence of written records of their tsunami effects in Australia is found. The devastating megathrust earthquake of 26 December 2004 occurred on the interface of the Indo-Australian and Euro-Asian plates where the first plate subducts beneath the overriding second plate and the Indo-Australian plate begins its descent into the mantle. In the epicentral region, the Indo-Australian plate moves toward the northeast at a rate of about 7 cm/year relative to the Euro-Asian plate resulting in oblique convergence and partitioning into thrust-faulting. From the size of the earthquake, it is likely that the displacement on the fault plane was up to fifteen meters. As with the recent event, megathrust earthquakes often generate large tsunamis that cause damage over a much wider area than is directly affected by ground shaking near the earthquake’s rupture. The subduction zone continues further south of the Indonesian archipelago and that area is also a potential risk of producing a megathrust event that may affect coastal parts of northwest Australia. The tragic events of Boxing Day 2004 highlighted the importance of establishing a tsunami warning system for the Indian Ocean like the one for the Pacific. Issues like more and better instrumentation, and a long-term program to educate people in the region about the dangers of tsunamis, were identified as priorities. Of particular interest is the time for identifying and issuing alerts for such devastating earthquakes with possibility to reduce it in future for warning purposes. 相似文献
13.
14.
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
15.
巴基斯坦曼塞赫拉7.8级地震对中国大陆大震趋势影响的初步研究 总被引：1，自引：0，他引：1
讨论了喜马拉雅弧型地震构造带西反射弧地带(简称“西触角区”),大地震活动的基本特征及2005年10月巴基斯坦曼塞赫拉7.8级地震发生后,对中国大陆地震趋势的可能影响。西触角区(N30~45°,E61~80°)大震活动存在显著的时间上10年左右成组性及两次大震时间间隔小于1个月的爆发性,地点上的成丛性,兴都库什深震区的地震有一定先兆意义,与东触角区(N20~29°,E95~102°)大地震也存在较好的相关性。沿欧亚大陆与印度洋、澳州板块碰撞带上印尼苏门答腊8.9级地震后,再次发生巴基斯坦7.8级大地震,显示出这一板缘地震带正处于活跃状态。研究认为未来1~2年应注意西触角区尤其是天山地震带的大震连发的危险性及东触角区(缅甸及川、滇为主)发生响应性大地震的可能性。对中国大陆内部其他地区大震形势的影响可能不大。 相似文献
16.
T-波是由海底地震或者海陆边界俯冲带附近地震激发,并在海洋低速层中传播的声波.2004年12月26日,在印度洋东部印尼苏门答腊岛附近发生MW=9.3级大地震,其产生的能量在印度洋中激发了巨大的海啸,造成了严重的人员伤亡和财产损失,受到了世界科学家们极大的关注.本文从台站(PALK)及台站(DGAR)记录到的地震的信号中,提取出了清晰的高频T-波,并在频率域内分析,最终得到了T-波的频谱已及频率随时间变化图像.另外,通过对大地震时间域和频率域内T-波信号的分析,了解到此次大地震断层破裂过程持续的时间大致为500 s,其间伴随有两次明显的能量释放过程.分析数据表明两次能量释放过程的间隔大致为80~100 s.T-波分析将为推断海洋地震以及海陆边界俯冲带附近地震的特征,提供一种独立的研究手段和方法. 相似文献
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An interpretation of the type, size, and interrelations of sources is proposed for the three large Aleutian earthquakes of March 9, 1957, May 7, 1986, and June 10, 1996, which occurred in structures of the Andreanof Islands. According to our interpretation, the earthquakes were caused by steep reverse faults confined to different structural units of the southern slope of the Andreanof Islands and oriented along the strike of these structures. An E-W reverse fault that generated the largest earthquake of 1957 is located within the Aleutian Terrace and genetically appears to be associated with the development of the submarine Hawley Ridge. The western and eastern boundaries of this source are structurally well expressed by the Adak Canyon in the west (～177°W) and an abrupt change in isobaths in the east (～173°W). The character of the boundaries is reflected in the focal mechanisms. The source of the earthquake of 1957 extends for about 300 km, which agrees well with modern estimates of its magnitude (M w = 8.6). Because the earthquake of 1957 caused, due to its high strength, seismic activation of adjacent areas of the Aleutian island arc, its aftershock zone appreciably exceeded in size the earthquake source. Reverse faults that activated the seismic sources of the earthquakes of 1986 and 1996 were located within the southern slope of the Andreanof Islands, higher than the Aleutian Terrace, outside the seismic source of the 1957 earthquake. The boundaries of these sources are also well expressed in structures and focal mechanisms. According to our estimate, the length of the 1986 earthquake source does not exceed 130–140 km, which does not contradict its magnitude (M w = 8). The length of the 1996 earthquake source is ～100 km, which also agrees with the magnitude of the earthquake (M w = 7.8). 相似文献
20.
在大地震发生后,快速准确地获得地震震源信息对应急救援十分重要,但是现有技术方法往往难以在快速准确地获取地震震源机制的同时获得破裂空间的分布特征。文章在传统W-phase反演技术的基础上开发了多点源W-phase反演方法,实现对大震破裂空间尺度上能量释放特征及震源机制的快速测定,并以2004年苏门答腊MW 9.1大地震为例,测试程序的有效性。研究中设置了1、2、3、4、5、6个点源来分别测定此次地震的能量释放特征及震源机制。结果显示,震源机制随着空间位置由南向北的变化与俯冲面走向变化一致,与设定点源附近的历史地震震源机制高度吻合。因此,基于多点源的W-phase快速反投影技术将能更好获得大震空间能量释放特征,为震后应急及海啸预警提供科学支持。 相似文献