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1.
The 12 to 13 July 2003 andesite lava dome collapse at the Soufrière Hills volcano, Montserrat, provides the first opportunity to document comprehensively both the sub‐aerial and submarine sequence of events for an eruption. Numerous pyroclastic flows entered the ocean during the collapse, depositing approximately 90% of the total material into the submarine environment. During peak collapse conditions, as the main flow penetrated the air–ocean interface, phreatic explosions were observed and a surge cloud decoupled from the main flow body to travel 2 to 3 km over the ocean surface before settling. The bulk of the flow was submerged and rapidly mixed with sea water forming a water‐saturated mass flow. Efficient sorting and physical differentiation occurred within the flow before initial deposition at 500 m water depth. The coarsest components (～60% of the total volume) were deposited proximally from a dense granular flow, while the finer components (～40%) were efficiently elutriated into the overlying part of the flow, which evolved into a far‐reaching turbidity current.  相似文献   

2.
广西合山马滩大隆组的沉积序列研究及其环境指示意义   总被引：1，自引：1，他引：1  
马滩地区的大隆组,以火山碎屑岩和硅质岩沉积为主。镜下研究表明,火山碎屑岩可分为凝灰岩、沉凝灰岩和凝灰质沉积岩3亚类共8种岩石微相;硅质岩可分为生物成因硅质岩和生物火山成因硅质岩两亚类共5种岩石微相。这些岩石微相构成了12种主要的岩石相,而岩石相垂向上组成了6种主要的沉积序列。沉积序列指示该区存在两种类型的浊流沉积,一种是水下火山喷发形成的火山碎屑流向高密度浊流进而向低密度浊流演化的沉积,一种是早期沉积的凝灰质和硅质生物颗粒在滑塌作用下形成的浊流沉积。沉积序列研究并结合马滩地区大隆组沉积时期的古地形,表明当时该区不易发育海底扇沉积,而易接受低密度浊流沉积,形成了连续性好的较薄层沉积。  相似文献   

3.
长白山火山灾害及其对大型工程建设的影响   总被引：2，自引：0，他引：2  
刘松雪  刘祥 《世界地质》2005,24(3):289-292
长白山火山是世界著名的活火山,历史时期有过多次喷发,有再次爆发的危险.长白山火山最大的一次爆发发生在公元1199-1200年,这次大爆发的火山灰最远到达距其1 000km远的日本北部.依据这次大爆发由火山喷发空中降落堆积物、火山碎屑流和火山泥流造成的巨大火山灾害,预测了长白山火山未来爆发火山灾害的类型、强度和范围,并编制了长白山火山未来爆发火山喷发空中降落堆积物灾害预测图、火山碎屑流灾害预测图和火山泥流灾害预测图.该研究可预防和减轻火山灾害,指导核电站等大型工程选址.  相似文献   

4.
火山喷发过程所伴生的地震活动会诱发大量的崩塌滑坡次生灾害,其所造成的人员财产损失甚至超过火山活动本身。2002年以来长白山天池火山区地震活动的异常,表明火山深部的岩浆正在发生变化,天池火山存在喷发的危险。地震崩塌滑坡的危险性区划是降低生命财产损失的有效手段。将火山伴生地震作为崩塌滑坡灾害的诱发因素并据此设置地震参数,利用简化的Newmark累积位移模型,考虑地形因素对地震的放大效应,对长白山地区天池火山喷发下次生崩塌、滑坡灾害的危险性进行评价。通过探讨不同地震震级下的危险性分区结果,认为不同地震参数的设置对危险性分区结果没有影响。将研究区划分为极高、高、中等、低、极低等5个危险等级,其中,极高危险区主要分布在3个区域:以天池口为中心,40km为半径的范围内;沿江乡—两江镇—松江镇条带区域;长白县境内鸭绿江沿岸区域。  相似文献   

5.
Merapi is Indonesia's most dangerous volcano with a history of deadly eruptions. Over the past two centuries, the volcanic activity has been dominated by prolonged periods of lava dome growth and intermittent gravitational or explosive dome failures to produce pyroclastic flows every few years. Explosive eruptions, such as in 2010, have occurred occasionally during this period, but were more common in pre‐historical time, during which a collapse of the western sector of the volcano occurred at least once. Variations in magma supply from depth, magma ascent rates and the degassing behaviour during ascent are thought to be important factors that control whether Merapi erupts effusively or explosively. A combination of sub‐surface processes operating at relatively shallow depth inside the volcano, including complex conduit processes and the release of carbon dioxide into the magmatic system through assimilation of carbonate crustal rocks, may result in unpredictable explosive behaviour during periods of dome growth. Pyroclastic flows generated by gravitational or explosive lava dome collapses and subsequent lahars remain the most likely immediate hazards near the volcano, although the possibility of more violent eruptions that affect areas farther away from the volcano cannot be fully discounted. In order to improve hazard assessment during future volcanic crises at Merapi, we consider it crucial to improve our understanding of the processes operating in the volcano's plumbing system and their surface manifestations, to generate accurate hazard zonation maps that make use of numerical mass flow models on a realistic digital terrain model, and to utilize probabilistic information on eruption recurrence and inundation areas.  相似文献   

6.
This research focuses on providing information related to the damaging effects of the 2010 eruption of Merapi volcano in Central Java, Indonesia. This information will be used to help emergency responders to assess losses more timely and efficiently, and to monitor the progress in emergency response and recovery. The objectives of this research are: (a) to generate a map of pyroclastic deposits based on activities pre- and post-volcano eruption of 2010 in the research area, (b) to investigate the impact of volcano eruption on the environment, and (c) to assess the impact of volcano eruption on landuse. ALOS PALSAR remote sensing data pre- and post-disaster were used in this research for mapping the volcano eruption. Topographic and geomorphological maps were analyzed for profiling and field orientation, which were used to investigate the impact of volcano eruption on the environment. SPOT 4 satellite images were used in this research for updating landuse information from the topographic map. The result of the landuse updated data was used for assessment of the volcano eruption’s impact on landuse with the GIS raster environment. The volcanic eruption that occurred in 2010 is estimated to have an impact of 133.31 ha for settlements, 92.32 ha for paddy fields, 235.60 ha for dry farming, 570.98 ha for plantations, 380.86 ha for bare land, and 0.12 ha for forest areas. An estimate of the number of buildings damaged due to the volcano eruption in 2010 was carried out by overlaying a map of pyroclastic deposits and the information point of the building sites from the topographic map. The total number of buildings damaged is estimated to be around 12,276 units.  相似文献   

7.
The Puy de Dôme volcano is a trachytic lava dome, about 11,000 y old. New pyroclastic layers originating from the volcano itself were discovered covering the summit and the flanks of the volcano. These pyroclastic layers do not fit with the previous interpretation, assuming a non-explosive dome-forming eruption. The tephra display pyroclastic surge features and exhibit fresh trachytic lapilli, basement lithics, allogeneous basaltic lava and clinker fragments requiring an open vent eruption. This ultimate eruption occurred after a period of rest, long enough for vegetation to develop on the volcano, as evidenced by carbonized plant fragments. Radiocarbon dating of some of these fragments gave an age of c.10,700 y also suggesting a significant rest duration.  相似文献   

8.
The eruption of Vesuvius of 79 AD caused extensive destructions all over the Campanian area, engulfing the cities of Pompeii, Herculaneum, Oplonti and Stabiae.The eruption followed a long quiescence period and the inhabitants of the area were surprised by the volcanic events. The first part of the eruption was characterized by a widespread dispersal of pumices from a high erup-tive column. The second part of the eruption, character-ized by pyroclastic flows emplacement, caused the major damages with extensive life losses in most of the towns surrounding the volcano. In Pompeii, the major casual-ties during the first phase resulted from roof collapses;during the second phase, people were killed either by physical trauma due to the kinetic energy of the flow or by suffucation because of the ash-rich atmosphere.  相似文献   

9.
卡特拉火山近期活动频繁,其喷发概率、喷发规模、喷发方式及影响都备受瞩目.通过收集整理若干资料和分析计算,采用“将古论今”的研究方法,初步得到了关于卡特拉火山未来可能的行为方式及影响.根据卡特拉火山喷发的历史规律,估算2013年的喷发概率约为30%.卡特拉火山下次喷发规模可能为4级或5级,其喷发方式有3种:其一是岩浆冲破巨厚冰层发生爆破性喷发;其二是正常的岩浆喷发;其三是夭折的喷发.但根据现有资料分析,卡特拉火山最有可能是以见不到喷发的形式结束这次不稳定性活动.   相似文献   

10.
Landsliding is a significant process on volcanic edifices, with individual events exceeding several cubic kilometres in volume. The causes of such mass movements and their relationship with volcanic activity are still poorly understood. Landslide events are an important factor in the evolution of volcanic islands such as Tenerife, where vertical and lateral collapses have occurred repeatedly. Subaerial and submarine processes related to landslide events strongly influence the morphology of the island. On Tenerife there are three very big valleys, Güimar, La Orotava and Icod, that have been created by large landslide events with ages ranging from Upper Pliocene to Middle Pleistocene. The landslides affect the northern flanks of the island and the slopes of a large central volcanic edifice, the Las Canadas volcano, which is truncated by the Las Canadas caldera, a multicyclic collapse depression, formed between 1.02 and 0.17 Ma. We have focused our studies on the potential for caldera collapse events to trigger large scale landslides. The available geological and morphological information has been incorporated into numerical models, which simulate the destabilising effects of a caldera collapse episode. The results of the numerical modelling indicate that processes associated with caldera collapse events can overcome the stabilising forces on the volcano flank and trigger landslides. We propose that caldera collapse events may have triggered large landslides on the slopes of the Las Canadas volcano.  相似文献   

11.
By means of multi-temporal analysis of satellite images and statistical algorithms, the amount of pyroclastic material deposited on Lascar volcano walls after the gravitational collapse of the eruptive column caused by the eruption that occurred on April the 19th and the 20th in 1993 was determined and quantified. For this analysis, scenes corresponding to Landsat 4 TM in 1989 and Landsat 7 ETM+ in 2001 were used. By careful selection methods such as combination of bands, unsupervised classification, and the Karhunen–Loève transform, detailed analysis of zones of change that correspond to pyroclastic deposits were made. This analysis was complemented with in situ data in order to correct and calibrate the satellite images to identify zones of 1993s eruption pyroclastic deposits. Using Kittler’s and other thresholding algorithms, a search was performed for a proper threshold to binarize the images to determine the surface area covered by the eruptive process. Matlab™ software was used both for general programming and for digital image processing.  相似文献   

12.
In this paper,we describe three strata at the distal part of the pyroclastic-flow from the Tianchi volcano in 1215(±15) eruption.One of the strata with crosslayers that are different from typical pyroclastic-flow strata may come from a ground-surge.The grain-size and scanning electron microscopy(SEM) analysis was performed to study the origin of the pyroclastic-flow.Characteristics of grain-size distribution show that it is similar with the ash cloud.Through the SEM analyses,we found some quench structures with less damage on the surfaces of the vitric pumices.These phenomena indicate that there has been hydration in the transportation processes at the distal of pyroclastic-flow.It has partly changed the transportation mechanism of pyroclastic-flow,which transitions form dense flow to diluted flow.This paper develops a new distal pyroclastic-flow model in the Tianchi volcano that can be divided into three stages,i.e.the quench stage,expanding stage and depositing stage.  相似文献   

13.
Thermoluminescence dating of four volcanic samples (material of eruption ejecta), from the island of Yiali near the Nissyros volcano in the southeastern Aegean sea, Greece, has revealed, for first time, a volcanic eruption which occurred during the 2nd millennium B.C. (c. 1460 B.C.), different from the known Santorini eruption. The interrelation between Yiali and the well-known Santorini eruption, as well as the implications of these eruptions regarding their potential impact to the Aegean prehistoric archaeology (demise of the Minoan civilization), are discussed. © 1996 John Wiley & Sons, Inc.  相似文献   

14.
长白山天池地区全新世以来火山活动及其特征   总被引：10，自引：0，他引：10  
长白山火山全新世规模最大的喷发活动发生在公元1199-1200年,即800年前的大爆发,被确定为普林尼或布里尼(Plinian)式喷发。这次大爆发形成体积巨大的、分布广泛的以空中降落堆积物为主的火山喷发碎屑堆积物,在长白山火山周围,远至日本都留下了地质记录。文章辨认并划分了这次大爆发火山碎屑物的成因类型:火山喷发空中降落堆积物(airfalltephra)、火山碎屑流(pyroclasticflow)状堆积物和火山泥流(lahar)堆积物,并且点、面结合,近、远和国内、国外兼顾,分析了这些火山碎屑物的主要特征、分布和相互关系,进而确定这些火山碎屑物分别属于两次普林尼式爆发。第1次(早期)普林尼式爆发称赤峰期,火山喷发模式为:普林尼式喷发柱(赤峰空落浮岩层)-火山碎屑流(长白山火山碎屑流层),随即主要由火山碎屑流诱发火山泥流(二道白河火山泥流层);第2次(晚期)普林尼式爆发称园池期,喷发模式为:普林尼式喷发柱(园池空落浮岩火山灰层)-火山碎屑流(冰场火山碎屑流层)。在层序上将气象站期碱流岩置于800年前大爆发火山碎屑物之下是正确的,其时代为晚更新世-全新世早期。  相似文献   

15.
内蒙锡林浩特鸽子山火山地质研究   总被引：4，自引：3，他引：1  
鸽子山火山位于内蒙古自治区锡林浩特市东南,处于大兴安岭-大同新生代火山喷发带中段,是锡林浩特-阿巴嘎火山群中保存最为完好的一座玄武质火山。火山喷发物的分布面积约55km2,主要为降落火山渣、溅落熔结火山碎屑岩和熔岩流,成分主要为碧玄岩,晚期有少量的橄榄拉斑玄武岩,碧玄岩中含有较多二辉橄榄岩包体和辉石及歪长石巨晶。火山由锥体、熔岩流和火山碎屑席组成,锥体由早期的降落锥和晚期溅落锥复合而成。火山口经历多次塌陷而成为破火口。锥体西侧及北东侧出露两个仍保留了原始形态的熔岩溢出口,熔岩流类型为结壳熔岩,由多个岩流单元组成,局部地区的熔岩流中发育较多保存完好的喷气锥、喷气碟或喷气塔。火山碎屑席主要分布在锥体的东侧,厚度由锥体向外逐渐减薄。火山活动可分为早、晚两个阶段,早期为爆破式喷发,形成火山渣锥和碎屑席,属亚布里尼型喷发,晚期主要为溢流式喷发,形成溅落锥和大规模熔岩流,其活动时代为晚更新世末-全新世。  相似文献   

16.
四海龙湾玛珥湖沉积物中碱流质火山灰的来源及其意义   总被引：5，自引：1，他引：5  
四海龙湾玛珥湖位于东北新生代龙岗火山区内,在玛珥湖沉积物距湖底69-70cm处分离出新鲜的火山灰。根据火山灰产出的层位、原生沉积特征、形貌和碱流质化学成分特征,属于长白山天池火山公元1199-1200年大喷发的产物。这一结果不仅表明天池火山历史时期大喷发的规模比原来估计的还要大,并且为建立千年以来四海龙湾沉积物及古气候演化的时间标尺提供了依据。  相似文献   

17.
Numerical models for simulation of mass flows are typically focussed upon accurately predicting the paths, travel times and inundation from a single flow or collapse event. When considering catchment-based hazards from a volcano, this is complicated by often being faced with several possible scenarios. Over the last 800 years at Mt. Taranaki/Egmont, a number of dome growth and collapse events have resulted in the genesis and emplacement of block-and-ash flows (BAFs). Each BAF was directed northwestward by a breach in the crater rim. The latest dome collapse events in the AD 1880s and AD 1755 inundated the northwestern flank and had run-out lengths 10 km from source. Future activity of this type could have a devastating effect on the Taranaki region’s communities, infrastructure and economy. Hazard planning has involved constructing volcanic hazard maps based upon the areas inundated by past volcanic flows, with little consideration of present-day topography. Here, a numerical geophysical mass flow modelling approach is used to forecast the hazards of future comparable BAF events on NW Mt. Taranaki. The Titan2D programme encompasses a “shallow water”, continuum solution-based, granular flow model. Flow mechanical properties needed for this approach include estimates of internal and basal friction as well as the physical dimensions of the initial collapse. Before this model can be applied to Taranaki BAFs, the input parameters must be calibrated by simulating a range of past collapse events. By using AD 1860 and AD 1755 scenarios, initial collapse volumes can be well constrained and internal and basal friction angles can be evaluated through an iterative approach from previous run-out lengths. A range of possible input parameters was, therefore, determined to produce a suite of potentially inundated areas under present-day terrain. A suite of 10 forecasts from a uniformly distributed range were combined to create a map of relative probabilities of inundation by future BAF events. These results were combined in a GIS package to produce hazard zones related to user-specified hazard thresholds. Using these input parameter constraints, future hazard forecasts for this scale and type of event can also take into account changing summit and topographic configurations following future eruptive or collapse events.  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.
李霓  Nicole  METRICH  樊祺诚 《岩石学报》2006,22(6):1465-1472
长白山天池火山在公元一千年左右曾发生过大规模喷发，其产物为大面积分布的灰白色碱流质浮岩和碎屑流，在其斑晶矿物橄榄石、钙铁辉石和碱性长石中均可见到熔融包裹体。在最主要的斑晶矿物——碱性长石中含有数量众多且个体也较大的熔融包裹体，多数含有一个以上的气泡，其中部分含有子晶，根据形貌特征的不同可分为截然不同的两组包裹体。这些熔融包裹体带有大量喷发前地下岩浆的信息，成为研究地下深部的岩浆在复杂的溢流-爆炸喷发中所发生变化的最好媒介。也是本文的研究对象，通过其中挥发份尤其是水的含量，可以推知天池火山发生大喷发的原因。经Nicolet Magna-IR 550红外光谱仪测定，这些熔融包裹体的含水量较高，达1．6％-3．6％，为当时天池火山发生了巨大规模爆炸喷发的原因提供了强有力的证据。但目前红外光谱仪的应用范围还比较有限，有待今后拓宽其应用领域。  相似文献   

20.
松辽盆地徐家围子断陷营城组火山岩相和火山机构分析   总被引：47，自引：0，他引：47  
陈建文  李长山 《地学前缘》2000,7(4):371-379
徐家围子断陷营城组火山岩极为发育。文章通过对火山岩的岩芯观察、薄片鉴定、岩芯测试及测井资料、二维、三维地震资料的综合分析 ,将营城组火山岩盆地分为 3大相区 ,即火山喷发区、过渡区和沉积区。火山喷发区岩性由各种熔岩、火山碎屑岩和少量砂砾岩组成 ;过渡区岩性以火山碎屑岩与沉积岩互层为特征 ,夹少量火山熔岩 ;沉积区岩性包括砂砾岩、砂岩、粉砂岩和泥岩。火山喷发区内可识别出 8种类型的火山岩相 (空落相、溢流相、基底涌流相、火山碎屑流相、火山泥石流相、火山沉积相、次火山相、隐爆角砾岩相 )和 3种类型的火山机构 (层火山、微型盾火山和渣锥火山 )。不同类型的火山机构具有不同火山作用、岩相分布特征和含油气性。因此火山岩相及火山机构分析对火山作用研究和油气勘探均有重要意义。  相似文献   

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