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1.
Based on the analysis of tectonic feature and geodynamic characteristics of regional faults systems in the southeast Asia, 9 source zones capable of generating tsunamis affecting Vietnamese coast were delineated in the South China Sea and adjacent sea areas. Statistical methods were applied to estimate the seismic hazard parameters for each source zone, which can be used for the detail tsunami hazard assessment in the future. Maximum earthquake magnitude is predicted for the Manila Trench (8.3?C8.7), the Sulu Sea (8.0?C8.4), and the Selebes Sea source zones (8.1?C8.5). Among the source zones, the Manila Trench, west of the Philippines is considered as a most potential tsunami source, affecting the Vietnamese coast. The estimated M max values were used to develop simple scenarios (with a point source assumption) to calculate the tsunami travel time from each source zone to the Vietnamese coast. The results show that for the Manila Trench source zone, tsunami can hit the Vietnamese coast in 2?h at the earliest. 相似文献
2.
Historical tsunami records in the South China Sea are collected and analyzed in this paper. There have been about 54 tsunamis in the South China Sea since 1076. The impacts of the transoceanic tsunamis on the southeast coast of China are weak. However, the regional tsunamis in the South China Sea bring varying degrees of influence to the south coast of China, which occurred about 18 times. By the analysis of the potential tsunami sources in the South China Sea, numerical simulations of tsunami induced in the Manila Trench are carried out. It is found that the tsunami wave height is small near Haikou if the general earthquake tsunami occurred. But the tsunami wave height is large when a giant earthquake of M9.3 occurred. If this extreme situation arises, the impacts to the coast of Haikou will be serious. 相似文献
3.
浊流是远距离沉积物运输的一种重要方式,海底浊流广泛存在于海底峡谷或海沟。马尼拉海沟位于南海东北部,是一条正在活动的板块汇聚边界。独特的地理位置(亚热带—热带)和气候条件(台风频发),使得马尼拉海沟浊流频发,然而,现今对马尼拉海沟的浊流研究甚少。本研究通过对马尼拉海沟北部水深3747 m处重力柱岩心(GEO6)进行高精度的粒度及沉积学特征分析,探讨马尼拉海沟浊流沉积规律。GEO6岩心底部细颗粒沉积物中浮游有孔虫的14C的AMS年龄为1405 a B.P.。高精度的粒度分析(0.25 cm)和沉积学特征显示: GEO6岩心记录有至少11次浊流沉积(T1-T11),且这些浊流都有明显的底部粒度最粗(砂质粉砂或砂)、向上粒度逐渐变细的正粒序特征,只有T8沉积体为反粒序特征,可能为异重流沉积。结合区域地质资料,本研究认为1.4 ka B.P.以来,研究区频繁的台风带来了大量陆源松散沉积物堆积在马尼拉海沟上游(高屏峡谷),不稳定的构造环境及地震频发导致这些松散沉积物垮塌并向下游马尼拉海沟输送,在海沟内形成频繁发育的浊流沉积体。 相似文献
4.
浊流是远距离沉积物运输的一种重要方式,海底浊流广泛存在于海底峡谷或海沟。马尼拉海沟位于南海东北部,是一条正在活动的板块汇聚边界。独特的地理位置(亚热带—热带)和气候条件(台风频发),使得马尼拉海沟浊流频发,然而,现今对马尼拉海沟的浊流研究甚少。本研究通过对马尼拉海沟北部水深3747 m处重力柱岩心(GEO6)进行高精度的粒度及沉积学特征分析,探讨马尼拉海沟浊流沉积规律。GEO6岩心底部细颗粒沉积物中浮游有孔虫的14C的AMS年龄为1405 a B.P.。高精度的粒度分析(0.25 cm)和沉积学特征显示: GEO6岩心记录有至少11次浊流沉积(T1-T11),且这些浊流都有明显的底部粒度最粗(砂质粉砂或砂)、向上粒度逐渐变细的正粒序特征,只有T8沉积体为反粒序特征,可能为异重流沉积。结合区域地质资料,本研究认为1.4 ka B.P.以来,研究区频繁的台风带来了大量陆源松散沉积物堆积在马尼拉海沟上游(高屏峡谷),不稳定的构造环境及地震频发导致这些松散沉积物垮塌并向下游马尼拉海沟输送,在海沟内形成频繁发育的浊流沉积体。 相似文献
5.
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
6.
台湾岛以南海域(台南滨海)弧—陆碰撞带位于欧亚板块、菲律宾海板块和南海的结合部位,是新近纪弧—陆碰撞研究的理想场所。本文通过对南海973航次在该区域的多道地震剖面的解释,认为台南滨海弧—陆碰撞带增生的火山—沉积楔由恒春海脊和高屏斜坡两部分组成,前者是菲律宾海板块的增生楔,后者是欧亚板块的增生楔,在增生楔体和火山弧之间是作为弧前盆地的北吕宋海槽。自中新世中期以来,南海洋壳开始沿着马尼拉海沟向菲律宾海板块俯冲,形成活动大陆边缘的增生部分——恒春海脊;与此同时菲律宾海板块开始向北西方向移动,前缘的吕宋岛弧距今6.5Ma以来朝着亚洲陆缘斜向汇聚,形成了被动大陆边缘的增生部分——高屏斜坡。由于菲律宾海板块和欧亚板块之间的斜向汇聚,弧—陆碰撞具有穿时性,造山作用首先发生在台湾岛的北部,然后向南部及台南滨海发展。 相似文献
7.
Located at the end of the northern Manila Trench,the Hengchun Peninsula is the latest exposed part of Taiwan Island,and preserves a complete sequence of accretionary deep-sea turbidite sandstones.Combined with extensive field observations,a’source-to-sink’approach was employed to systematically analyze the formation and evolutionary process of the accretionary prism turbidites on the Hengchun Peninsula.Lying at the base of the Hengchun turbidites are abundant mafic normal oceanic crust gravels with a certain degree of roundness.The gravels with U-Pb ages ranging from 25.4 to23.6 Ma are underlain by hundreds-of-meters thickness of younger deep-sea sandstone turbidites with interbedded gravels.This indicates that large amounts of terrigenous materials from both the’Kontum-Ying-Qiong’River of Indochina and the Pearl River of South China were transported into the deep-water areas of the northern South China Sea during the late Miocene and further eastward in the form of turbidity currents.The turbidity flow drastically eroded and snatched mafic materials from the normal South China Sea oceanic crust along the way,and subsequently unloaded large bodies of basic gravel-bearing sandstones to form turbidites near the northern Manila Trench.With the Philippine Sea Plate drifting clockwise to the northwest,these turbidite successions eventually migrated and,since the Middle Pleistocene,were exposed as an accretionary prism on the Hengchun Peninsula. 相似文献
8.
西太平洋边缘构造带是地球上规模最大最复杂的板块边界,以台湾和马鲁古海为界,自北往南大致可以分为3段。北段是典型的沟-弧-盆体系,千岛海盆、日本海盆及冲绳海槽均为典型的弧后扩张盆地。中段菲律宾岛弧构造带为双向俯冲带,构造复杂,新生代经历大的位移和重组,使得欧亚大陆边缘的南海、苏禄海和苏拉威西海成因存在很大的争议。南段新几内亚—所罗门构造带是太平洋板块、印度—澳大利亚及欧亚板块共同作用的结果,既有不同阶段的俯冲、碰撞,也有大规模的走滑与弧后的扩张,其间既有新扩张的海盆,又有正在俯冲消亡的海盆。台湾岛处于枢纽部位,欧亚板块在此被撕裂,南部欧亚大陆边缘南海洋壳沿马尼拉海沟俯冲于菲律宾岛弧之下,而北部菲律宾海洋壳沿琉球海沟俯冲欧亚大陆之下。马鲁古海是西太平洋板块边界又一转折点,马鲁古海板块往东下插于哈马黑拉之下,往西下插于桑义赫弧,形成反U形双向俯冲汇聚带,其洋壳板块已基本全部消失,致使哈马黑拉弧与桑义赫弧形成弧-弧碰撞。 相似文献
9.
台湾-吕宋岛双火山弧的构造意义 总被引：3，自引：0，他引：3
扼要评介了国内外关于台湾-吕宋岛双火山弧在南海沿马尼拉海沟俯冲的动力学过程和俯冲板块深部形态等方面研究的成果;认为目前的动力学模式还不够完善,没有能够对台湾-吕宋岛双火山弧中存在的第四纪火山间断做出合理的解释,为此引入“板片窗”概念,对已经提出的动力学模式进行了修改;并统计1964~2006年发生于菲律宾地区的地震震中位置,认为存在于菲律宾群岛17°~19°N之间的深源地震稀疏带和存在于14°~15°N之间的喇叭状地震稀疏带是地震作用对于南海板片窗构造存在的反映;结合研究区域已有应力场研究资料,认为俯冲的南海亚板块中板片窗两侧俯冲倾角的差异,应该是造成俯冲带内应力分布出现分带现象的原因之一。 相似文献
10.
利用中国地震台网和ISC台站记录的P波到时数据,采用球坐标系有限差分地震层析成像方法反演了南海东北部及其邻近地区壳幔三维P波速度结构,并分析了不同地质单元的构造差异及其深部特征。结果表明:南海东北部表现出陆架地区的岩石层特性,属于华南大陆向海区的延伸,岩石层厚度较大,现今不存在大规模的地幔热流活动,推测大陆边缘张裂作用仅限于地壳内部而没有延伸进入上地幔,具有非火山型大陆边缘的深部特点。中央海盆附近上地幔P波速度明显降低,与海盆下方地幔热流活动密切相关。不同的速度异常特征表明:华南大陆暨台湾地区属于欧亚大陆的正常地壳或是与菲律宾海板块相互作用产生的增厚型地壳,冲绳海槽则是弧后扩张产生的减薄型地壳。滨海断裂带作为华南大陆高速异常和南海北部高速异常的分界,代表了一定地质时期华南地块和南海地块的拼合边界。断裂附近的上地幔低速异常揭示了闽粤沿海岩浆作用的深层动力机制。吕宋岛弧、马尼拉海沟、东吕宋海槽的速度异常与其所处的特殊构造位置有密切的关系,清晰地反映出岛弧俯冲带的地壳结构差异;台湾南部至吕宋岛弧的上地幔低速异常揭示了两个重要火山链的深部构造特征,北吕宋海脊下方100 km深度的条带状高速异常有可能代表了俯冲下沉的岩石层板片。 相似文献
11.
During the Paleogene the Proto-South China Sea was subducted beneath northern Borneo. Subduction ended with Early Miocene collision of the Dangerous Grounds/Reed Bank/North Palawan block and the Sabah–Cagayan Arc. Much of northern Borneo then became emergent forming the Top Crocker Unconformity. Later in the Early Miocene subsidence resumed. It is proposed that northward subduction of the Celebes Sea initiated formation of the Sulu Sea backarc basin, followed by subduction rollback to the SE. This formed a volcanic arc, which emerged briefly above sea level and collapsed in the Middle Miocene. As rollback continued the Sulu Arc was active during Middle and Late Miocene between Sabah and the Philippines. Rollback drove extension in northern Borneo and Palawan, accompanied by elevation of mountains, crustal melting, and deformation offshore. There were two important extensional episodes. The first at about 16 Ma is marked by the Deep Regional Unconformity, and the second at about 10 Ma produced the Shallow Regional Unconformity. Both episodes caused exhumation of deep crust, probably on low angle detachments, and were followed by granite magmatism. The NW Borneo–Palawan Trough and offshore Sabah fold and thrust belt are often interpreted as features resulting from collision, regional compression or subduction. However, there is no seismicity, dipping slab or volcanicity indicating subduction, nor obvious causes of compression. The trough developed after the Middle Miocene and is not the position of the Paleogene trench nor the site of Neogene subduction. Inboard of the trough is a thick sediment wedge composed of an external fold and thrust belt and internal extensional zone with structures broadly parallel to the trough. The trough is interpreted as a flexural response to gravity-driven deformation of the sediment wedge, caused by uplift on land that resulted from extension, with a contribution of deep crustal flow. 相似文献
12.
Simulation of the Arabian Sea Tsunami propagation generated due to 1945 Makran Earthquake and its effect on western parts of Gujarat (India) 总被引：1，自引：1，他引：0
The 1945 Tsunami generated due to Makran Earthquake in the Arabian Sea was the most devastating tsunami in the history of
the Arabian Sea and caused severe damage to property and loss of life. It occurred on 28th November 1945, 21:56 UTC (03:26
IST) with a magnitude of 8.0 (M
w), originating off the Makran Coast of Pakistan in the Arabian Sea. It has impacted as far as Mumbai in India and was noticed
up to Karvar Coast, Karnataka. More than 4,000 people were killed as a result of the earthquake and the tsunami. In this paper
an attempt is made for a numerical simulation of the tsunami generation from the source, its propagation into the Arabian
Sea and its effect on the western coast of India through the use of a numerical model, referred to as Tunami-N2. The present
simulation is carried out for a duration of 300 min. It is observed from the results that the simulated arrival time of tsunami
waves at the western coast of India is in good agreement with the available data sources. The paper also presents run-up elevation
maps prepared using Shuttle Radar Topographic Mission (SRTM) data, showing the possible area of inundation due to various
wave heights along different parts of the Gujarat Coast. Thus, these results will be useful in planning the protection measures
against inundation due to tsunami and in the implementation of a warning system. 相似文献
13.
Abstract. The aseismic Palawan microcontinental block is an oceanic bathymetric high that has collided with the seismically-ac-tive Philippine Mobile Belt since the Early Miocene. Consequently, tectonic microblocks immediately north (Luzon) and south (Western Visayas Block) of the collision front rotated in opposite senses. The rotation led the microblocks to onramp adjacent strike-slip faults, and converted these to subduction zones, namely, the current Manila and Negros Trenches. In addition, the collision also initiated the southward propagation of a major left-lateral strike slip fault, the Philippine Fault Zone, and the Philippine Trench, which bounds the Philippine archipelago along its eastern boundary. Based on onshore and offshore data, the Philippine Fault Zone and the East Luzon Trough - Philippine Trench appears to also propagate northward. Furthermore, the opposite direction of propagation is also noted for the Manila and Negros Trenches from the locus of the collision in the Central Philippines to their northern and southern extensions, respectively. The ages of initiation of the Manila Trench (Early Miocene), Philippine Fault Zone (Middle Miocene) and Philippine Trench (Pliocene) as encountered along a west to east transect in the Central Philippines are consistent with the collision and subsequent indentation of Palawan with the rest of the Philippine Mobile Belt. 相似文献
14.
Comparison of linear and nonlinear shallow wave water equations applied to tsunami waves over the China Sea 总被引：4，自引：0，他引：4
Yingchun Liu Yaolin Shi David A. Yuen Erik O. D. Sevre Xiaoru Yuan Hui Lin Xing 《Acta Geotechnica》2009,4(2):129-137
This paper discusses the applications of linear and nonlinear shallow water wave equations in practical tsunami simulations.
We verify which hydrodynamic theory would be most appropriate for different ocean depths. The linear and nonlinear shallow
water wave equations in describing tsunami wave propagation are compared for the China Sea. There is a critical zone between
400 and 500 m depth for employing linear and nonlinear models. Furthermore, the bottom frictional term exerts a noticeable
influence on the propagation of the nonlinear waves in shallow water. We also apply different models based on these characteristics
for forecasting potential seismogenic tsunamis along the Chinese coast. Our results indicate that tsunami waves can be modeled
with linear theory with enough accuracy in South China Sea, but the nonlinear terms should not be neglected in the eastern
China Sea region. 相似文献
15.
南海东北部台湾浅滩陆坡的浊流沉积物波的发育及其成因的构造控制 总被引：3，自引：0，他引：3
南海东北部马尼拉海沟发育有面积达35 000 km2的、壮观的沉积物波波域,水深2 600～4 100 m。基于波域的特征、区域分布、物质组成等,判断其为重力流成因。该波域于1.2 Ma开始起动,从而形成了和下伏平行反射截然不同的波状反射,二者之间为沉积物波的起动面。该波域的发育史受控于台湾造山运动的发育史,吕宋岛弧在北西西向运动的菲律宾海板块的携带下,于6.5 Ma左右和欧亚大陆边缘发生斜向弧—陆碰撞,碰撞焦点持续向南转移,于1.2 Ma左右转移至台湾南部,造成台湾南部的物理剥蚀、乃至向毗邻深水的碎屑供应急剧增加,改变了深水沉积动力学状态,浊流活动的强度和频率极大加强,从而开始了该波域的起动和发育。该沉积物波的发育和台湾造山运动构成了完美的构造活动和沉积响应关系。 相似文献
16.
Ian S. F. Jones 《Journal of Earth System Science》2002,111(3):209-213
The Sulu Sea, located between Borneo and the Philippines, is separated from the surrounding ocean by two chains of islands.
There are no passages below 500 m depth and the basin, which at the deepest is 5,000m, is filled with warm low oxygen water.
The near surface chlorophyll concentration has been examined with the aid of ocean colour sensors on board satellites. Direct
comparisons between a field observation of chlorophyll and its remotely sensed values from OCTS (Ocean Colour Temperature
Scanner) are found to be in satisfactory agreement. An 8-month time series of chlorophyll near the centre of the Sulu Sea
has been used to show that the chlorophyll level is significantly higher than the level in the adjacent South China Sea. This
was most pronounced at the period of change between the monsoons. The greater primary productivity may provide the explanation
for the higher deposition rate of carbon in the Sulu Sea.
Although the Sulu Sea is more productive than the adjacent South China Sea, the central area can still be classified as a
desert. Estimates of the new primary production in the central Sulu Sea seem to be just sufficient to support the current
fishery. 相似文献
17.
To clarify the generating mechanism of the 2011 Tohoku-oki earthquake (Mw 9.0) and the induced tsunami, we determined high-resolution tomographic images of the Northeast Japan forearc. Significant lateral variations of seismic velocity are visible in the megathrust zone, and most large interplate thrust earthquakes are found to occur in high-velocity (high-V) areas. These high-V zones may represent high-strength asperities at the plate interface where the subducting Pacific plate and the overriding Okhotsk plate are coupled strongly. A shallow high-V zone with large coseismic slip near the Japan Trench may account for the mainshock asperity of the 2011 Tohoku-oki earthquake. Because it is an isolated asperity surrounded by low-velocity patches, most stress on it was released in a short time and the plate interface became decoupled after the Mw 9.0 earthquake. Thus the overriding Okhotsk plate there was shot out toward the Japan Trench and caused the huge tsunami. 相似文献
18.
Taiwan is located in the axis of the Manila Trench. It results from an oblique collision between the northernmost part of the Luzon arc and the Chinese passive margin. This active collision follows the subduction of the Oligocene-Miocene oceanic crust of the South China Sea along the Manila Trench. The tectonized Chinese margin emerged in the Hengchun peninsula (South Taiwan). Gentle folds which are delineated by the Quaternary reefal limestones demonstrate Recent deformations. These folds deformed a thick detrital sequence of Miocene age (Ssuchung Chi series) which was previously strongly folded and thrust westward (axis NS-N20) upon the Renting mélange of Latest Miocene age. These main deformations, sealed by the Middle Pliocene, are the evidence for the onset of collision in this part of Taiwan at the end of the Miocene. Because of its obliquity, the collision started already in the northern part of Taiwan during the Late Miocene (6-7-8 Ma ?).The Ssuchung Chi series, a sequence of proximal turbidites, has contained, since the Middle Miocene (NN 6~13 Ma), fragments of an Oligocene to Lower Miocene oceanic crust. This ophiolitic material is very similar to the East Taiwan Ophiolite of the Coastal Range. It originated most probably from a slice of South China Sea crust obducted in Middle Miocene times (13–14 Ma) upon the Chinese margin (North of the Hengchun peninsula). This obduction occurred 7 to 8 Ma before the beginning of collision. These results make it possible to propose an evolutionary model for Taiwan from the Oligocene to the Recent, with the different phases of a collision between a volcanic arc and a passive margin. 相似文献
19.
20.
Assessing the threat to Western Australia from tsunami generated by earthquakes along the Sunda Arc 总被引：1，自引：1，他引：1
A suite of tsunami spaced evenly along the subduction zone to the south of Indonesia (the Sunda Arc) were numerically modelled
in order to make a preliminary estimate of the level of threat faced by Western Australia from tsunami generated along the
Arc. Offshore wave heights from these tsunami were predicted to be significantly higher along the northern part of the west
Australian coast than for the rest of the coast south of the town of Exmouth. In particular, the area around Exmouth may face
a higher tsunami hazard than other areas of the West Australian coast nearby. Large earthquakes offshore of Java and Sumbawa
are likely to be a greater hazard to WA than those offshore of Sumatra. Our numerical models indicate that a magnitude 9 or
above earthquake along the eastern part of the Sunda Arc has the potential to significantly impact a large part of the West
Australian coastline.
The Australian government reserves the right to retain a non-exclusive, royalty free license in and to any copyright. 相似文献