五大连池老黑山、火烧山的火山喷发特征

从野外调查及火山喷发观测记录入手, 结合国内外火山研究的新进展, 在火山成因类型、喷发方式及喷发前兆等方面讨论了五大连池老黑山、火烧山的火山喷发特征。指出老黑山、火烧山的火山成因类型属于单成因火山, 喷发方式不是简单的中心式喷发, 而是经历了裂隙式喷发后转为中心式喷发。通过火山喷发观测记录的分析及与国外火山对比, 揭示出此次火山喷发是有前兆的, 其前兆特征对监测预报未来火山喷发有借鉴意义。     

On Selection of Analog Volcanoes

Estimating the occurrence probability of volcanic eruptions with VEI ??3 is challenging in several aspects, including data scarcity. A?suggested approach has been to use a simple model, where eruptions are assumed to follow a Poisson process, augmenting the data used to estimate the eruption onset rate with that from several analog volcanoes. In this model the eruption onset rate is a random variable that follows a gamma distribution, the parameters of which are estimated by an empirical Bayes analysis. The selection of analog volcanoes is an important step that needs to be explicitly considered in this model, as we show that the analysis is not always feasible due to the required over-dispersion in the resulting negative binomial distribution for the numbers of eruptions. We propose a modification to the method which allows for both over-dispersed and under-dispersed data, and permits analog volcanoes to be chosen on other grounds than mathematical tractability.     

Records of palaeo‐sea level and eruption duration in a coastal tuff ring,Jeju Island,Korea

Phreatomagmatic volcanoes and their sedimentary products can preserve high‐resolution records of earth surface processes because of their high deposition rate. Songaksan, Jeju Island, Korea, is a phreatomagmatic volcano, which erupted c. 3.7 ka BP in a coastal setting. Its tuff ring preserves a record of intertidal to supratidal facies transition in the basal part, which reveals the position of palaeo‐high‐tide level for at least 13 high‐tide events, and a record of a storm‐surge event in the middle part of the tuff ring, which lasted approximately three tidal cycles. Based on these features, the phreatomagmatic eruption of Songaksan is estimated to have taken place over a month. The sea level at the time was almost identical to that at present. This study shows that coastal phreatomagmatic volcanoes can preserve high‐resolution records of eruption duration and palaeo‐sea level, and can provide accurately levelled and dated data points to the Quaternary sea‐level curve.     

五大连池老黑山火烧山火山喷发方式的探讨

从反映五大连池老黑山、火烧山火山喷发方式的几个事实入手,通过与当代著名的裂隙式喷发火山——新托尔巴奇克火山对比,探讨老黑山、火烧山的喷发方式,说明它们先经由裂隙式喷发,而后转为中心式喷发。     

Probabilities of future VEI ≥ 2 eruptions at the Central American Volcanic Arc: a statistical perspective based on the past centuries’ eruption record

A probabilistic eruption forecast is provided for seven historically active volcanoes along the Central American Volcanic Arc (CAVA), as a pivotal empirical contribution to multi-disciplinary volcanic hazards assessment. The eruption probabilities are determined with a Kaplan–Meier estimator of survival functions, and parametric time series models are applied to describe the historical eruption records. Aside from the volcanoes that are currently in a state of eruptive activity (Santa María, Fuego, and Arenal), the highest probabilities for eruptions of VEI ≥ 2 occur at Concepción and Cerro Negro in Nicaragua, which are likely to erupt to 70–85 % within the next 10 years. Poás and Irazú in Costa Rica show a medium to high eruption probability, followed by San Miguel (El Salvador), Rincón de la Vieja (Costa Rica), and Izalco (El Salvador; 24 % within the next 10 years).     

中国东部全新世火山的镭-钍同位素年代学

活火山是指1万年来有过喷发历史的全新世火山。火山的高分辨年代学对火山灾害评估和火山分类具有重要意义。对于缺乏历史记载的全新世火山,直接对火山岩进行同位素定年很困难。本文利用具有高时间分辨率的镭-钍-铀非平衡确定中国东部年轻火山的年龄。根据镭-钍-铀同位素,海南岛的马鞍岭和雷虎岭是全新世火山(马鞍岭:4.3ka;雷虎岭:4.7ka);镜泊湖火山(4.9ka)也是全新世火山;龙岗火山存在晚更新世和全新世活动(7.0ka,15.0ka);大兴安岭阿尔山和诺敏河Ra/Th非平衡消失但~(230)Th/~(238)U非平衡显著,属于晚更新世喷发(阿尔山:63ka;诺敏河:71ka)。海南岛的马鞍岭火山、雷虎岭火山和东北地区的龙岗火山、镜泊湖火山,是4座活火山。至于东北地区的阿尔山和诺敏河火山是否是活火山,有待测试更多样品的Ra/Th同位素。五大连池老黑山和火烧山有历史喷发记录,这与它们都存在显著Ra/Th非平衡一致。五大连池老黑山和火烧山的岩浆滞留年龄分别小于4.2ka和3.2ka,岩浆上升速率 18～23m/y。     

长白山火山公元1199～1201年喷发的历史记录

长白山天池火山是世界著名的火山之一,是我国规模最大、最具有潜在喷发危险的一座近代活动火山。目前,国内外许多火山学者为了研究天池火山最近一次大喷发年代问题,做了大量工作,并取得了一些年代资料,但一直没取得有关这次大喷发历史记载的证实。笔者等再次收集和查阅了一亿七千万字的文史古籍资料,通过整理、筛选、考证、对比和分析处理, 发现了长白山天池火山,于公元1199～1201年一次大喷发的历史记录。这对于长白山天池火山未来喷发危险性的研究具有重要的意义。     

长白山天池火山公元1199—1200年大喷发历史记载的发现及其意义

长白山天池火山是世界著名的火山之一,是我国规模最大、最具有潜在喷发危险的一座近代活动火山。目前国内外许多火山学者为了研究天池火山最近一次大喷发年代问题,做了大量工作,并取得了较为精确的＾１４Ｃ年代资料,但地直未取得有关这次大喷发历史记载的证实。本文通过再次收集和查阅上千万字的文史古籍资料进行整理、筛选、考证和分析,首次发现了白头山天池火山于公元１１９９￣１２００年间一次特大喷发的历史记载。这对于长     

The Vulnerability of Canada to Volcanic Hazards

Western Canada lies in a zone of active tectonics and volcanism, but thedispersed population has witnessed few eruptions due to the remoteness of the volcanoes and their low level ofactivity. This has created a false perception that Canada's volcanoes are extinct.There are more than 200 potentially-active volcanoes in Canada, 49of which have erupted in the past 10,000 years. They occur in five belts, with origins related totectonic environment. The minimum annual probability of a Canadian volcanic eruption is approximately 1/200;for an effusive (lava) eruption the probability is about 1/220, and for a significant explosive eruptionit is about 1/3333. In-progress studies show that there have been earthquakes associated with at least 9 ofthe youngest Canadian volcanoes since 1975. A scenario of an eruption of Mt. Cayley (50.1°N,123.3°W) shows how western Canada is vulnerable to an eruption. The scenario is basedon past activity in the Garibaldi volcanic belt and involves both explosive and effusive activity.The scenario impact is largely a result of the concentration of vulnerable infrastructure in valleys.Canadian volcanoes are monitored only by a regional seismic network,that is capable of detecting a M > 2 event in all potentially-active areas.This level of monitoring is probably sufficient to alert scientistsat or near eruption onset, but probably insufficient to allow a timelyforecast of activity. Similarly the level of geological knowledge about the volcanoes is insufficient to createhazard maps. This will improve slightly in 2002 when additional monitoring is implemented in theGaribaldi volcanic belt. The eruption probabilities, possible impacts, monitoring limitations and knowledgegaps suggest that there is a need to increment the volcanic risk mitigation efforts.     

From sink to volcanic source: Unravelling missing terrestrial eruption records by characterization and high‐resolution chronology of lacustrine volcanic density flow deposits,Lake Inawashiro‐ko,Fukushima, Japan

Eruption records in the terrestrial stratigraphy are often incomplete due to erosion after tephra deposition, limited exposure and lack of precise dating owing to discontinuity of strata. A lake system and sequence adjacent to active volcanoes can record various volcanic events such as explosive eruptions and subaqueous density flows being extensions of eruption triggered and secondary triggered lahars. A lacustrine environment can constrain precise ages of such events because of constant and continuous background sedimentation. A total of 71 subaqueous density flow deposits in a 28 m long core from Lake Inawashiro‐ko reveals missing terrestrial volcanic activity at Adatara and Bandai volcanoes during the past 50 kyr. Sedimentary facies, colour, grain size, petrography, clay mineralogy, micro X‐ray fluorescence analysis and chemistry of included glass shards characterize the flow event deposits and clarify their origin: (i) clay‐rich grey hyperpycnites, extended from subaerial cohesive lahars at Adatara volcano, with sulphide/sulphate minerals and high sulphur content which point to a source from hydrothermally altered material ejected by phreatic eruptions; and (ii) clay‐rich brown density flow deposits, induced by magmatic hydrothermal eruptions and associated edifice collapse at Bandai volcano, with the common presence of fresh juvenile glass shards and low‐grade hydrothermally altered minerals; whereas (iii) non‐volcanic turbidites are limited to the oldest large slope failure and the 2011 Tohoku‐oki earthquake events. The high‐resolution chronology of volcanic activity during the last 50 kyr expressed by lacustrine event deposits shows that phreatic eruption frequency at Adatara has roughly tripled and explosive eruptions at Bandai have increased by ca 50%. These results challenge hikers, ski‐fields and downstream communities to re‐evaluate the increased volcanic risks from more frequent eruptions and far‐reaching lahars, and demonstrate the utility of lahar and lacustrine volcanic density flow deposits to unravel missing terrestrial eruption records, otherwise the recurrence rate may be underestimated at many volcanoes.     

长白山天池火山公元1014-1019年大喷发的历史记录

长白山火山是世界著名的火山之一，是我国规模最大、最具有潜在喷发危险的一座近代活动火山。目前，国内外许多火山学者为了研究长白山火山最近一次大喷发年代问题，做了大量工作，并取得了一些年代资料，但一直未取得有关这次大喷发历史记载的证实。笔者等通过再次收集和查阅了大量文史古籍资料，通过整理、筛选、考证、对比和分析处理，首次发现了长白山（白头山）火山，于公元1014～1019年间一次大喷发的历史记载。这对于研究长白山火山喷发历史具有重要的意义。     

金星薄饼状火山类比研究

金星薄饼状火山(陡边火山)是一类形貌非常独特的火山,有别于太阳系中其他的火山:近圆的底面轮廓、平坦的顶部和较大的顶底直径比.薄饼状火山被认为是高黏度岩浆喷发形成的,但是这一成因并不被广泛接受.火山的形貌特征主要取决于岩浆成分、喷发机制、重力和喷发环境(如大气压)等.因此,通过对比地球火山的形貌特征及形成机制可以为金星薄饼状火山的成因提供指示.我们利用底面不规则度(ii )、高径比(H/W B )、顶底直径比(W S/W B )、侧边最大坡度处的标准化高度(HS m a x )、顶部高径比(H S/W S )和喷发量(V )这些形貌参数定量地将地球表面的复式火山、盾形火山、火山锥、熔岩穹丘(Peleean 型和 Coulees 型)、海底平顶火山以及泥火山的形貌特征与金星薄饼状火山对比.Coulees型熔岩穹丘、海底平顶火山和泥火山的形貌特征与金星薄饼状火山有一定的相似性.Coulees型熔岩穹丘剖面形态与薄饼状火山最为相似,可能指示了薄饼状火山具有类似的成因机制,而海底平顶火山侧边的上凹特征可能指示了其与薄饼状火山完全不同的成因机制.因此,薄饼状火山可能是相对高黏度的岩浆以较高速率持续性喷发形成.     

火山信息系统建立方法研究——以长白山火山区为例

火山喷发是严重的地质灾害之一。全球各地都有火山分布 ,我国也有近千座火山。其中长白山火山、五大莲池火山和腾冲火山是我国最具潜在灾难性喷发危险的活火山。以长白山火山为例 ,阐述用建立火山信息系统的方法监测、预测、评估火山灾害 ,达到减灾、防灾的目的     

内蒙古达里诺尔晚新生代火山群喷发特征研究

达里诺尔火山群有近百座晚新生代单成因火山,其地质地貌形态各异,喷发形式多样。这些火山既有爆破式喷发,如:夏威夷式喷发,斯通博利式喷发,强斯通博利式喷发和射汽岩浆喷发;也有溢流式喷发,如盾状火山;还有岩浆缓慢侵出,如大黑山。火山群内典型火山机构表明,不同的喷发方式穿插于火山喷发过程:早期火山活动多以侵出和溢流为主,逐渐转变为岩浆爆破式喷发(强斯通博利式,斯通博利式),晚期又过渡为溢流式喷发,喷发过程大体经历一个爆破强度弱-强-弱的转变。射汽岩浆型的火山则是以剧烈的射汽岩浆爆炸开始,后期逐渐转弱为岩浆爆破喷发和溢流喷发。火山喷发过程中火山产物出现牛顿流体,宾汉流体,层流,颗粒流,涌流,空降等不同类型的运动形式,自火口向远源运动,形成差异化的火山产物。岩浆的输送速率、上升速度,以及围岩的类型,可能是造成达里诺尔火山群多样化喷发的主要因素。     

火山学述评

火山学研究有了长足的进步。笔者总结近些年全球火山学研究各个方面的成果,包括对火山基本概念的新的认识、火山机构、火山的各种分类、火山岩石学和地球化学、火山岩相学、评估火山爆发大小的火山爆发指数、岩石和地球化学分类、各种常量和微量元素区分图、活火山分布与板块构造理论的关系、活火山给人类带来的灾害与利益和活火山的监测、曾经的火山活动与生物毁灭、单成因火山研究等。火山—构造是未来火山学研究的一个方向,通过火山与构造关系的研究以揭示火山的分布和地球的演化。火山喷出的岩浆是其通过地下以岩墙或管道形式为通道运移到地表的结果。中朝边境上的长白山的位置是个特例,应当值得深入的研究。中国分布有许多新生代火山,它们是否为单成因火山、这些火山在成分上是否有演化规律、它们的分布与大地构造的关系等都有待深入和系统的研究。     

Evaluation of earthquake-induced strain in promoting mud eruptions: the case of Shamakhi–Gobustan–Absheron areas,Azerbaijan

Although a relationship between the occurrence of large earthquakes and the eruptions of close mud volcanoes is well known, several uncertainties remain on understanding the triggering mechanisms. In the present study, we evaluate both the static and dynamic strains induced by earthquakes in the substratum of mud volcanoes. We studied the effects of two earthquakes of M _w 6.18 and 6.08 occurred in the Caspian Sea on 25 November 2000 close to Baku city, Azerbaijan. A total of 33 eruptions occurred at 24 mud volcanoes within a maximum distance of 108 km from the epicentres in the 5 years following the earthquakes. The overall eruption rate in the studied area of the 50 years before the 2000 earthquakes was 1.24 that is much smaller than the eruption rate of 6.6 of the 5 years following these earthquakes. The largest number of eruptions occurred within 2 years from the earthquakes with the highest frequency within 6 months. Our calculated earthquake-induced static effects show that crustal dilatation might have triggered only seven eruptions at a maximum distance of about 60 km from the epicentres and within 3 years. Based on our data, dynamic rather than static strain is likely to have been the dominating “promoting” factor because it affected all the studied unrest volcanoes and its magnitude was much larger.     

Estimation of tsunami hazard from volcanic activity — Suggested methodology with Augustine volcano,Alaska as an example

A general approach for the estimation of tsunami height and hazard in the vicinity of active volcanoes has been developed. An empirical relationship has been developed to estimate the height of the tsunami generated for an eruption of a given size. This relationship can be used to estimate the tsunami hazard based on the frequency of eruptive activity of a particular volcano. This technique is then applied to the estimation of tsunami hazard from the eruption of the Augustine volcano in Alaska. Modification of this approach to account for a less than satisfactory data base and differing volcanic characteristics is also discussed with the case of the Augustine volcano as an example. This approach can be used elsewhere with only slight modifications and, for the first time, provides a technique to estimate tsunami hazard from volcanic activity, similar to a well-established approach for the estimation of tsunami hazard from earthquake activity.     

全球主要火山灾害及其分布特征

本文研究了火山灾害各种致灾因子的物理过程和灾害特点,根据文献中记载的全球火山灾害,在进行火山灾害分区研究的基础上,研究了全球火山灾害分布特征.全球主要的火山灾害分布在8个主要区域.有记载的火山灾害在热带占73%,远高于火山喷发分布于热带区的比例.全球两个最强烈的火山灾害分布区都是围绕着位于板块结合部表现为复杂构造结的班达海和加勒比海,而且每一个灾害区都有3条分支.热带区第3个灾害区为中非区,地幔上隆是这里主要的动力学背景.本文还研究了1700年以来火山灾害时间分布特征,以及1993年以来各种火山灾害发生频次.     

Spectral Characterisation of Tsunamis and Seiches Caused by Tectonism and Volcanism in Rabaul,Papua New Guinea

Tsunamis originating in Indonesia and Papua New Guinea can be locally devastating and also occasionally threaten coastal areas of northern Australia. Tsunamis may be caused by earthquakes, volcanoes or submarine landslides. In Rabaul a unique set of records exists of tsunamis and seiches generated by tectonic earthquakes, volcanic earthquakes and a volcanic eruption. Spectral analysis of the digitised waveforms has been undertaken to compare the effects of the different sources and to estimate the characteristic natural periods of Rabaul Harbour. Seiches in Rabaul Harbourhave dominant periods of 20 to 30 min, a period band that is also typical for coastal recordings of tsunamis.     

Mud volcano eruptions and earthquakes in the Northern Apennines and Sicily, Italy

The relations between earthquakes and the eruption of mud volcanoes have been investigated at the Pede–Apennine margin of the Northern Apennines and in Sicily. Some of these volcanoes experienced eruptions or increased activity in connection with historical seismic events, showing a good correlation with established thresholds of hydrological response (liquefaction) to earthquakes. However, the majority of eruptions have been documented to be independent of seismic activity, being mud volcanoes often not activated even when the earthquakes were of suitable magnitude and the epicentre at the proper distance for the triggering. This behaviour suggests that paroxysmal activity of mud volcanoes depends upon the reaching of a specific critical state dictated by internal fluid pressure, and implies that the strain caused by the passage of seismic waves can activate only mud volcanoes in near-critical conditions (i.e., close to the eruption). Seismogenic faults, such as the Pede–Apennine thrust, often structurally control the fluid reservoirs of mud volcanoes, which are frequently located at the core of thrust-related folds. Such an intimate link enables mud volcanoes to represent features potentially suitable for recording perturbations associated with the past and ongoing tectonic activity of the controlling fault system.