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1.
The 2004 tsunami that struck the Sumatra coast gave a warning sign to Malaysia that it is no longer regarded as safe from a future tsunami attack. Since the event, the Malaysian Government has formulated its plan of action by developing an integrated tsunami vulnerability assessment technique to determine the vulnerability levels of each sector along the 520-km-long coastline of the north-west coast of Peninsular Malaysia. The scope of assessment is focused on the vulnerability of the physical characteristics of the coastal area, and the vulnerability of the built environment in the area that includes building structures and infrastructures. The assessment was conducted in three distinct stages which stretched across from a macro-scale assessment to several local-scale and finally a micro-scale assessment. On a macro-scale assessment, Tsunami Impact Classification Maps were constructed based on the results of the tsunami propagation modelling of the various tsunami source scenarios. At this stage, highly impacted areas were selected for an assessment of the local hazards in the form of local flood maps based on the inundation modelling output. Tsunami heights and flood depths obtained from these maps were then used to produce the Tsunami Physical Vulnerability Index (PVI) maps. These maps recognize sectors within the selected areas that are highly vulnerable to a maximum tsunami run-up and flood event. The final stage is the development of the Structural Vulnerability Index (SVI) maps, which may qualitatively and quantitatively capture the physical and economic resources that are in the tsunami inundation zone during the worst-case scenario event. The results of the assessment in the form of GIS-based Tsunami-prone Vulnerability Index (PVI and SVI) maps are able to differentiate between the various levels of vulnerability, based on the tsunami height and inundation, the various levels of impact severity towards existing building structures, property and land use, and also indicate the resources and human settlements within the study area. Most importantly, the maps could help planners to establish a zoning scheme for potential coastline development based on its sensitivity to tsunami. As a result, some recommendations on evacuation routes and tsunami shelters in the potentially affected areas were also proposed to the Government as a tool for relief agencies to plan for safe evacuation.  相似文献   

2.
2004年12月26日,由于欧亚板块的碰撞,40年以来最大的地震灾害发生在印度洋。地震诱发的海啸影响到Nangroe Aceh Darussalam省的许多城市,包括省会城市班达阿齐。在这地区共有超过12万人死亡,100万人无家可归。基于遥感数据的分析表明,有12万亩的土地受到了灾害。在班达阿齐市,鱼塘、住宅用地和保护区的变化是这一地区最显著的土地利用/覆盖变化,受灾前后这些用地类型的面积相应的变化了61.5%、57.8% 和77.6%。目前,印度尼西亚中央政府正在计划一个新的海岸带土地利用规划,在原来密集的海岸带建立一个缓冲区(约距海岸带2 km)。政府已经要求许多海岸带的社区代表与非政府组织参与到决策的过程中。 为了选择并采取最佳的土地利用方式,海啸灾害后的海岸带规划应该包括一些重要的基本要素。本研究主要关注作为该省社会经济活动中心的班达阿齐市。检测了由于海啸灾害造成的土地利用/覆盖变化(包括物理破坏),特别是农业用地和居住区用地的变化,并且分析了受灾村落的不同类型及灾害对社会经济活动造成的影响。此外,还为政府以及当地居民在灾后的规划中选择更为可持续的空间布局方案提出了建议。  相似文献   

3.
Classifying inundation limits in SE coast of India: application of GIS   总被引:1,自引:0,他引:1  
A study on the possible inundation limit in SE coast of India was carried out using various physical, geological and satellite imageries. The coastal inundation hazard map was prepared for this particular region as it was affected by many cyclones, flooding, storm surge and tsunami waves during the last six decades. The results were generated using various satellite data (IRS-P6 LISS3; LANDSAT ETM; LANDSAT-5 ETM; LANDSAT MSS) and digital elevation models (ASTER GLOBAL DEM), and a coastal vulnerability index was generated for the entire coastal stretch of Nagapattinam region in SE coast of India. The coastal area which will be submerged totally due to a 1–5 m rise in water level due to any major natural disaster (tsunami or cyclone) indicates that 56–320 km2 will be submerged in this particular region. The results suggest that nearly 7 towns and 69 villages with 667,477 people will be affected and indicate that proper planning needs to be done for future development.  相似文献   

4.
藏北安多地区毗邻羌塘盆地南界,属于藏北地层分区。研究区沙木罗组地层为一套稳定的浅海相碎屑岩和碳酸盐岩建造,依次发育风化壳沉积,潮坪相沉积以及混合台地相沉积,有大量生物礁产出。本文通过对沙木罗组地层中采集到的18件样品进行常量、微量元素及碳氧同位素测试,结合沉积相分析,旨在探索本区晚侏罗世古海平面升降、氧化还原条件以及古气候的演化规律。研究发现,Ni、Sr、Cu、V、Cr、Ni/Co及δ~(13)C等变化能反映氧化还原环境的变化,而Mn、Na、Sr/Cu、P、Ti及δ~(18)O和Z值的波动能指示古气候的变化。研究结果表明:研究区的古环境演化共经历了3个阶段:(1)风化壳阶段的强氧化环境;(2)潮坪阶段的半氧化半还原环境;(3)台地区与三期生物礁建造相对应的3次氧化与还原环境转换。古气候演化也经历了3个阶段:(1)风化壳区的干旱气候;(2)潮坪区的半干旱半湿润气候;(3)台地区3次干湿气候的频繁转换,分别与本区的3个造礁期相对应。  相似文献   

5.
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   

6.
张八岭地区变质地层序列与构造型式   总被引:6,自引:0,他引:6  
运用构造与地层相结合的理论和方法,通过对张八岭地区已完成和正在进行的10幅1:5万地质填图资料分析和典型地区的构造追踪,初步认为:北将军(岩)组自下而上分为三段,时代置于中元古代,获铅同位素年龄样值为1821±416Ma;西冷(岩)组自下而上分为三段,时代置于青白口纪。区内主要存在三期构造交形:早期为一系列呈NWW-近EW向的紧闭同斜褶皱,中期以韧性剪切带发育为特征,晚期以NNE向为主的宽缓褶皱。三期变形共同叠加,形成区内基本构造格架。并对变形机制作初步探讨。  相似文献   

7.
A combined approach of field geology and numerical simulation was conducted for evaluating the tsunami impacts on the shelf sediments. The 2003 Tokachi-oki earthquake, M 8.0, that occurred on 25 September 2003 off southeastern Hokkaido, northern Japan, generated a locally destructive tsunami. Maximum run-up height of the tsunami waves reached 4 m above sea level. In order to estimate the tsunami impacts on shallow marine sediments, we compared pre- and post-tsunami marine sediments in water depths of 38–112 m in terms of grain size, sedimentary structure, and microfossil content. Decreases of fine fractions, especially finer than very fine sand, which led to coarsen the mean grain size, were detected in the inner shelf of the northern part of the study area. Foraminiferal assemblages also changed in the coarsened sediments. On the other hand, the other shelf sediments largely unchanged or slightly fined. We also simulated the tsunami wave velocity and direction, and grain size entrained by the modeled tsunami. The numerical simulation resulted in that the 2003 tsunami could transport very fine sand in water depths shallower than 45–95 m at the northern part of the study area. This is comparable with the actual grain-size changes after the tsunami had passed. However, some storms and tidal currents might also be possible to stir the surface sediments after the pre-tsunami survey, so we could not conclude that the grain-size changes had been caused only by the tsunami. Nevertheless, a combined approach of sampling and modeling was powerful for estimating the tsunami impacts under the sea.  相似文献   

8.
Probabilistic Tsunami Hazard Analysis (PTHA) can be used to evaluate and quantify tsunami hazards for planning of integrated community-level preparedness, including mitigation of casualties and dollar losses, and to study resilient solutions for coastal communities. PTHA can provide several outputs such as the intensity measures (IMs) of the hazard quantified as a function of the recurrence interval of a tsunami event. In this paper, PTHA is developed using a logic tree approach based on numerical modeling for tsunami generated along the Cascadia Subduction Zone. The PTHA is applied to a community on the US Pacific Northwest Coast located in Newport, Oregon. Results of the PTHA are provided for five IMs: inundation depth, flow speed, specific momentum flux, arrival time, and duration of inundation. The first three IMs are predictors of tsunami impact on the natural and built environment, and the last two are useful for tsunami evacuation and immediate response planning. Results for the five IMs are presented as annual exceedance probability for sites within the community along several transects with varying bathymetric and topographic features. Community-level characteristics of spatial distribution of each IM for three recurrence intervals (500, 1000, 2500 year) are provided. Results highlight the different pattern of IMs between land and river transects, and significant magnitude variation of IMs due to complex bathymetry and topographic conditions at the various recurrence intervals. IMs show relatively higher magnitudes near the coastline, at the low elevation regions, and at the harbor channel. In addition, results indicate a positive correlation between inundation depth and other IMs near the coastline, but a weaker correlation at inland locations. Values of the Froude number ranged 0.1–1.0 over the inland inundation area. In general, the results in this study highlight the spatial differences in IMs and suggest the need to include multiple IMs for resilience planning for a coastal community subjected to tsunami hazards.  相似文献   

9.
The failure of the Tous dam in 1982 caused one of the most important socio-natural disasters in Spain during the twentieth century. That event triggered a paradigm change in the way disaster risks were perceived and managed, not only locally, but also at multiple levels of governance. Fifteen interviews with relevant stakeholders, content analysis of scientific literature, and review of historical and media accounts indicate that the collapse of the Tous dam had the two major effects. First, it prompted a process of institutional development, which led to the growth, and increase in complexity of the organizations involved both in vertical and horizontal communication of disaster risk reduction. Second, actions taken and experiences gained in dealing with disaster risk reduction in the Tous area were used as a benchmark to develop new strategies, as well as new mechanisms for communication and planning in other territories and other risk domains in Spain. This paper also identified the three main stages in the evolution of disaster risk reduction planning in the area: (1) After the collapse of the Tous dam, disaster risk reduction strategies in Spain focused on improving preparedness in order to reduce short-term risks. (2) Disaster management in the 1990s was strongly influenced by international initiatives, which emphasized the contextualization of risk and the importance in long-term disaster risk reduction measures such as land-use planning. (3) The European Water Framework Directive (2000) and, more recently, the Floods Directive (2007) are exerting a strong influence on the development of a new Spanish flood policy that focuses on preventive measures. However, this process is far from complete and many issues still remain unresolved: dealing with different domains of risk action, integrating concepts of ecological resilience and climate change, and promoting public awareness and effective participation.  相似文献   

10.
Sue Dawson   《Sedimentary Geology》2007,200(3-4):328-335
Distinctive diatom assemblages may be associated with tsunami sediments and may often contrast with the assemblages found within sediments underlying the tsunami deposit as well as those associated with the modern coastal environment. Sediments associated with the 1998 tsunami that destroyed much of the Sissano lagoon area in northern Papua New Guinea have been investigated. Surface sediments from three transects across the sediment spit near Warapu have been examined for diatom content and preservation. The preservation is variable, and the data show an, often chaotic, assemblage that can be attributed to the tsunami waves incorporating and depositing diatoms from distinctive habitat zones during their runup and subsequent backwash. The diatoms identified within the Warapu sediments indicate an origin from within the inter-tidal and offshore area rather than from the beach–sand spit complex. The sand deposits disclose a high percentage, in excess of 75%, of broken diatom valves, and a predominance of centric (circular) species due to preferential preservation. The study demonstrates that the application of diatom biostratigraphy to modern tsunami deposits can be used in conjunction with other stratigraphical lines of evidence to interpret the source and provenance of historical and palaeo-tsunami deposits.  相似文献   

11.
王善书 《沉积学报》1985,3(4):121-130
南海北部指北纬16°00'至23°00'与东经108°00'至120°00'之间的海域。包括广东大陆以南、海南、台湾两岛之间的广阔大陆架和陆坡区以及北部湾。东西长约1300公里,南北宽约200至400公里。面积约40万平方公里。经过地球物理勘探普查工作及几十口钻井资料,证实该区第三纪沉积广泛分布,厚逾万米。按沉积岩厚度大于1000米所圈定的范围约在30万平方公里以上,形成了北部湾、莺歌海、琼东南、珠江口及台湾西南五个沉积盆地(图1、2)。在北部湾、琼东南、珠江口及台湾西南盆地中,分别在下第三系流沙港组、陵水组、珠江组,上第三系角尾组、韩江组发现了储油气层(表1)。  相似文献   

12.
Natural Hazards - The 2011 Tohoku-oki tsunami left a characteristic geochemical signature in the sediments of the Misawa harbor on the Aomori coastline (northern Japan), not only in vertical...  相似文献   

13.
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   

14.
De Lange  W. P.  Healy  T. R. 《Natural Hazards》2001,24(3):267-284
The Hauraki Gulf is a semi-enclosed sea next to the largest population centre in New Zealand, the Auckland metropolitan region. The potential tsunami hazard is of concern to regional and local planners around the Hauraki Gulf. The Hauraki Gulf has recorded 11 tsunamis and one meteorological tsunami (rissaga) since 1840.The historical tsunami data are relatively sparse, particularly for the largest events in 1868 and 1883. Moreover, local sources may produce damaging tsunamis but none has occurred during recorded history. Therefore numerical modelling of potential tsunami events provides a powerful tool to obtain data for planning purposes. Three main scenarios have been identified for numerical modelling:1. A teletsunami event from an earthquake off the West Coast of South America. Historically this region has produced the largest teletsunamis in the Hauraki Gulf.2. A tsunami generated by a local earthquake along the Kerepehi Fault. This fault bisects the Gulf, has been active during the last century at the southern inland end, and is overlain by a considerable thickness of soft sediment that may amplify the seismic waves.3. A tsunami generated by a volcanic eruption within the Auckland Volcanic Field. This field has involved a series of mainly monogenetic basaltic eruptions over the last 140,000 years. Many of these eruptions have involved phreatomagmatic eruptions around the coastal margins, or within the shallow waters close to Auckland.  相似文献   

15.
赣东北壳体构造演化与铜(金)多金属成矿系列   总被引:8,自引:2,他引:6  
赣东北地区是我国重要的铜(金)多金属矿化密集区。自晋宁运动以来该区壳体构造活动复杂而强烈,先后经历过三个不同性质的壳体构造发展阶段。每一阶段中均形成有各自不同性质和不同特点的合矿建造,并形成三套与之相应的铜(金)多金属成矿系列,即元古宙动力变质成矿系列。古生代喷流沉积成矿系列及中新生代火山一次火山成矿系列。  相似文献   

16.
Late Albian to Cenomanian upper shoreface deposits from the Grajaú Basin, northern Brazil, consist of well‐sorted, very fine‐ to fine‐grained sandstones with swaley, trough, tabular and minor hummocky cross‐stratification. A striking feature of these deposits is the abundance of large‐scale scour‐and‐fill structures, which consist of regularly spaced, repetitive, very shallow swales with either symmetrical or asymmetrical profiles, arranged along an undulose surface or as a succession of superimposed troughs. The sediment filling these scours is characterized by very fine‐grained sandstone with gently undulose, near‐parallel lamination to very low‐angle dipping cross‐stratification intergraded with swaley and hummocky cross‐stratification. The nature of the scours and the sedimentary structures of their fills reveal the action of combined flows, which are hydrodynamically similar to those developed during storms. However, it is speculated that the combined flows responsible for the genesis of these structures were formed by tsunami waves enhanced by tsunami‐induced ebb currents and/or tidal currents. This interpretation is proposed on the basis of several lines of reasoning: (1) palaeogeographic reconstructions of the study area during the late Cretaceous show that it was outside the belt favourable for the development of storms; (2) comparison of the scour‐and‐fill structures with stratigraphically correlatable deposits exposed north of the study area, where similar features occur in association with abundant seismically induced, soft‐sediment deformation structures; and (3) the presence of several styles of soft‐sediment deformation features (i.e. convolute lamination, bed collapse, large‐scale folds, massive bedding, sand‐filled fractures and diastasis cracks) are suggestive of synsedimentary seismic activity in Cretaceous deposits located in and near to the study area. This study proposes that episodic, high‐amplitude tsunami waves, enhanced by tsunami‐induced ebb currents, develop powerful flows capable of producing complex patterns of erosion and sedimentation, which may be represented by scour‐and‐fill structures similar to those described here.  相似文献   

17.
湖北东南部西临江汉平原,北抵襄广断裂及郯庐断裂,东南大致以省境线为界(图1),是我省的重要煤产地之一。1986—1987年,笔者和彭安群、汪颂桥等在这一地区研究了近20条上二叠统含煤岩系的沉积剖面,采集了部分样品,通过分析研究,对本区龙潭早期的沉积环境及聚煤作用有了初步的认识。晚二叠世早期,大致以大冶-嘉鱼断裂为界,北部武汉、黄石等地沉积了龙潭组;南部蒲圻、阳新一带沉积了吴家  相似文献   

18.
The eastern Mediterranean has been the cradle of many great civilizations. The history of the area consisted of glorious battles, heroic acts, and the rise and fall of great civilizations. But, sometimes, natural hazards became the cause for a new classification of the political, as well as of the military status quo of the region. The enormous eruption of the submarine volcano at the Greek island of Thera (Santorini) during the Bronze Age, around 1500 BC, is such a natural hazard. The tsunami generated by the eruption, literally wiped out the peace-loving Minoan civilization who inhabited the island of Crete. After the sea subsided, the configuration of the area was altered, and the decline of the Minoan principality on the Archipelago began. The present paper introduces evidence concerning the tsunami and states some of the after-effects which were partly responsible for the decline of the Minoan empire. All the information is gathered from historical sources and from recent research works. An effort has been made to include many of the theories introduced by various researchers through time concerning the event. Finally, information has been included from all known research, as well as from the author's own conclusions, in order to make the paper useful to future researchers.  相似文献   

19.
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   

20.
Kakawis Lake situated four metres above sea level on western Vancouver Island, British Columbia, Canada, was the target of a palaeotsunami investigation. Six percussion cores recovered from this lake contain six anomalous deposits interbedded within the unconsolidated lacustrine sediments. Detailed sedimentological, geophysical and macro-fraction analyses were performed. The methods new to palaeoseismic approaches proved to be successful tools to characterize the anomalously coarse layers enriched in terrestrial plant detritus and marine shells. Based on at least eight types of evidence, six tsunami inundations are suggested as mechanisms responsible for the anomalous deposition, spanning from 3,634 to 2,534 cal yrs BP. Each tsunami event consists of a combination of different lithological facies resulting from different stages of tsunami inundation and settling of the material in the lake basin (pulses and inter-pulses). Tsunami deposits in lakes are shown to be less vulnerable to erosional and bioturbation processes than those found in marshes or beaches as well as underwater marine environments. However, few palaeoseismic studies have been carried out in low-elevation lakes along the Cascadia Subduction Zone region. The three last tsunami events known to have inundated areas along the Pacific shores of southern British Columbia, Canada and northern USA are not present at Kakawis Lake, establishing a current <4 m above mean sea level vertical limit as possible maximum tsunami height for areas located away from fjord heads on Vancouver Island. The anomalous deposits found in Kakawis Lake may be the oldest geological evidence of inferred tsunami on Vancouver Island, providing a possible recurrence interval between 200 and 400 years.  相似文献   

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