全球地震、火山分布及其变化特征

地震和火山都反映了地球表层的构造活动,因而地震活动区往往也是火山活动区。根据全球大震、火山活动目录,分析研究了全球地震、火山分布的特征。描述了各区的地震、火山活动分布,总结了地震、火山活动强度的时、空分布特征。全球地震、火山活动可以分为碰撞带、大陆区和大洋区。大陆地震以其片状的分散分布而不同于板块边缘的带状分布,大陆火山活动比大洋火山更受应力场的影响。大洋区地震活动相对较弱,岩浆活动主要是平静的岩浆溢出与洋中脊的扩张,往往没有形成火山喷发。有记录的火山喷发主要来自深部地幔的热柱。俯冲-碰撞活动区地震活动与火山喷发最强烈,大角度俯冲的弧后火山活动最强,当板块运动方向与板块边缘走向成小角度相交时,缺少正面俯冲的动力,火山活动相对平静。>500km深震的地段,火山活动较弱。火山与地震强烈活动的大多在大地水准面(Geoid)异常高的区域。地震与火山平均纬度随时间表现出同步的变化外,火山和大震活动也显示了大致同步的变化     

2016年全球火山活动综述

通过对2016年全球活动火山监测信息的统计,2016年共有96座火山记录到喷发活动,主要分布在环太平洋俯冲带及印度板块与欧亚板块碰撞边界上。火山预警等级共有4个,可以标识火山的危险程度,本文根据火山每个预警等级在全年52次监测信息报道中的出现次数,将96座活动火山按危险程度划为4类,并对每类的火山活动作出了详细描述。2016年的火山喷发也造成了人员伤亡和财产损失,印度尼西亚是受火山灾害影响最严重的国家。此外,根据火山灰柱海拔高度的整理及近年活动火山数量的调查,推测2016年的火山活动仅会使火山附近区域的天气受到影响,应不会引起全球性的气候异常。      

近期阿贡火山(巴厘岛,印尼)喷发警戒等级已升至最高级

印度尼西亚岛链是西南太平洋最为活跃的一条"火链",生活在该火山区的居民数量也为世界之最,阿贡火山就是这条"火链"中最为活跃的火山之一。阿贡火山的喷发周期约为50年,其上一次喷发是在1963年(距今55年)。从2017年8月开始,阿贡火山的地震明显增多,有复苏和再次喷发的前兆,9月份火山警戒等级已升至为Ⅲ级,10月份开始有喷发柱喷出,11月喷发柱急剧上升至4 km并开始有岩浆活动,警戒等级也升至最高级(Ⅳ级)。本文整理分析了当地对阿贡火山的实时监测数据,展示了阿贡火山从开始活动以来,火山地震、形变、地球化学和遥感影像等的监测情况。     

腾冲火山地质研究述评

在综合分析前人有关腾冲火山研究成果的基础上，对该区火山活动的研究现状，火山活动特征，火山活动背景及火山活动与深部岩浆侵入活动的关系等进行了评述。认为腾冲火山群中存在全新世活火山，现今处于休眠状态，具有再次喷发的潜在危险性，因此，进一步深入研究腾冲火山在全新世活动的时间分布规律，对于在该区开展火山活动监测，减灾防灾等方面具有重要意义。     

长白山天池火山减灾对策初探

国内外专家学者认为，长白山天池火山是一座具潜在灾害性喷发危险的活火山，因此制定火山减灾对策理应提到议事日程。针对天池火山研究现状和火山灾害特点，制定了火山活动各阶段的减灾对策。中长期阶段应加强火山监测与研究和火山知识宣传工作，采取必要的工程防护措施，重大工程进行火山安全性评价，制定火山喷发应急预案；短期阶段请求国际火山流动监测台网给予支援；临近喷发阶段重点是有组织的撤离；喷发及其后阶段应及时救灾抢险，对火山喷发趋势进行科学判定，合理地重建家园。     

汤加火山2022年喷发回顾——对国内火山监测研究的启示

2022年1月15日汤加一座海底火山发生了猛烈的爆炸式喷发,喷出大量火山灰、气体与水蒸气,并进入平流层,形成巨大火山灰云团,引起国内外广泛关注.本文对汤加火山的地质构造背景、喷发历史、喷发过程、灾害影响、喷发机理等方面进行综合分析,详述此次汤加火山喷发的过程及灾害影响,由此引申到当前国内活火山的活动状态.长白山天池火山...     

太平洋板块俯冲对长白山天池火山的影响

长白山天池火山是我国最具潜在喷发危险的活火山之一,属于远离海沟的陆内火山.太平洋板块平卧于长白山天池火山的下方,其俯冲过程对长白山天池火山形成及活动具有重要意义.本文通过二维热力学耦合的数值模型对海洋板块俯冲的动力学过程进行了模拟,分析了海洋板块俯冲对远离海沟的陆内火山的深部温压条件、速度场、岩浆补给量等的影响.依据模拟结果探讨了太平洋板块对长白山天池火山活动影响的可能性及方式.     

我国现代火山的基本特点

本文根据我国现代火山所处的地质构造环境，将其划分为四种构造类型，即环太平洋火山、陆缘火山、碰撞带火山和大陆板内火山。分析了我国现代火山时在时间上的活动特点，喷发频率，火山喷发类型及其现代活动表现。提出了我国现代火山活动监测研究方向。     

长白山天池火山潜在喷发危险性讨论

根据吉林省新生代以来火山喷溢活动的时空演化历史，特别是全新世以来火山活动频民强度变化特征，以及现代喷发活动史记资料，结合１０多年火山动态观测数据，讨论了长白山天池潜在喷发的危险程度，认为其灾害性潜在喷发危险的时间尺度仍属于地质范畴。     

长白山天池火山研究进展

长白山天池火山距今４１０５年以来至少发生过两次大规模喷发。其最近的一次大喷发发生于公元８５０～１０４０年间。估计了这次喷发的喷发物体积和Ｃ１，Ｆ，Ｓ等的释放量。数值模拟表明，该次大喷发对全球气候变化产生过重要影响，最近的地球物理探测结果显示，在该火山下面存在地壳和上地幔双层岩浆房。认为该火山现在仍是一座具潜在灾害性大喷发危险的现代活动火山。     

2010年冰岛埃亚菲亚德拉火山喷发启示录——加强我国活动火山监测与研究刻不容缓

2010年3月开始的冰岛埃亚菲亚德拉火山喷发,火山灰肆虐欧洲,迫使很多机场关闭,航班取消,对世界的空中交通造成了极大的影响。本文分析了冰岛埃亚火山的喷发机制和灾害效应,回顾了近些年来我国在活动火山监测与研究领域取得的进展和存在的不足,强调了迅速加大我国火山监测与研究工作力度的重要性。     

PRELIMINARY VOLCANIC HAZARD ZONATION IN JINLONGDINGZI VOLCANO,LONGANG VOLCANO AREA,JILIN PROVINCE,CHINA

Longgang volcano cluster is 150km away from the Tianchi volcano, located in Jingyu and Huinan Counties, Jilin Province, China. It had a long active history and produced hundreds of volcanoes. The latest and largest eruption occurred between 1 500 and 1 600 years ago by Jinlongdingzi(JLDZ)volcano which had several eruptions in the history. This paper discusses the volcanic hazard types, and using the numerical simulations of lava flow obtained with the Volcflow model, proposes the hazard zonation of JLDZ volcano area. JLDZ volcano eruption type is sub-plinian, which produced a great mass of tephra fallout, covering an area of 260km². The major types of volcanic hazards in JLDZ area are lava flow, tephra fallout and spatter deposits. Volcflow is developed by Kelfoun for the simulation of volcanic flows. The result of Volcflow shows that the flows are on the both sides of the previous lava flows which are low-lying areas now. According to the physical parameters of historical eruption and Volcflow, we propose the preliminary volcanic hazard zonation in JLDZ area. The air fall deposits are the most dangerous product in JLDZ. The highly dangerous region of spatter deposits is limited to a radius of about 2km around the volcano. The high risk area of tephra fallout is between 2km to 9km around the volcano, and between 9km to 14km is the moderate risk area. Out of 14km, it is the low risk area. Lava flow is controlled by topography. From Jinchuan Town to Houhe Village near the volcano is the low-lying area. If the volcano erupts, these areas will be in danger.     

Perceptions of hazard and risk on Santorini

Santorini, Greece is a major explosive volcano. The Santorini volcanic complex is composed of two active volcanoes—Nea Kameni and Mt. Columbo. Holocene eruptions have generated a variety of processes and deposits and eruption mechanisms pose significant hazards of various types. It has been recognized that, for major European volcanoes, few studies have focused on the social aspects of volcanic activity and little work has been conducted on public perceptions of hazard, risk and vulnerability. Such assessments are an important element of establishing public education programmes and developing volcano disaster management plans. We investigate perceptions of volcanic hazards on Santorini. We find that most residents know that Nea Kameni is active, but only 60% know that Mt. Columbo is active. Forty percent of residents fear that negative impacts on tourism will have the greatest effect on their community. In the event of an eruption, 43% of residents would try to evacuate the island by plane/ferry. Residents aged >50 have retained a memory of the effects of the last eruption at the island, whereas younger residents have no such knowledge. We find that dignitaries and municipal officers (those responsible for planning and managing disaster response) are informed about the history, hazards and effects of the volcanoes. However, there is no “emergency plan” for the island and there is confusion between various departments (Civil Defense, Fire, Police, etc.) about the emergency decision-making process. The resident population of Santorini is at high risk from the hazards associated with a future eruption.     

Emergency planning and mitigation at Vesuvius: A new evidence-based approach

Disasters from explosive volcanic eruptions are infrequent and experience in emergency planning and mitigation for such events remains limited. The need for urgently developing more robust methods for risk assessment and decision making in volcanic crises has become increasingly apparent as world populations continue to expand in areas of active explosive volcanism. Nowhere is this more challenging than at Vesuvius, Italy, with hundreds of thousands of people living on the flanks of one of the most dangerous volcanoes in the world. We describe how a new paradigm, evidence-based volcanology, has been applied in EXPLORIS to contribute to crisis planning and management for when the volcano enters its next state of unrest, as well as in long-term land-use planning. The analytical approach we adopted enumerates and quantifies all the processes and effects of the eruptive hazards of the volcano known to influence risk, a scientific challenge that combines field data on the vulnerability of the built environment and humans in past volcanic disasters with theoretical research on the state of the volcano, and including evidence from the field on previous eruptions as well as numerical simulation modelling of eruptive processes. Formal probabilistic reasoning under uncertainty and a decision analysis approach have provided the basis for the development of an event tree for a future range of eruption types with probability paths and hypothetical casualty outcomes for risk assessment. The most likely future eruption scenarios for emergency planning were derived from the event tree and elaborated upon from the geological and historical record. Modelling the impacts in these scenarios and quantifying the consequences for the circumvesuvian area provide realistic assessments for disaster planning and for showing the potential risk–benefit of mitigation measures, the main one being timely evacuation, but include for consideration protecting buildings against dilute, low dynamic pressure surges, and temporary roof supports in the most vulnerable buildings, as well as hardening infrastructure and lifelines. This innovative work suggests that risk-based methods could have an important role in crisis management at cities on volcanoes and small volcanic islands.     

Effect of gas emissions from Tianchi volcano (NE China) on environment and its potential volcanic hazards

One of largest eruptions in the Tianchi volcano during the Holocene occurred in about 1000 years ago[1―3]. The volcanic ash erupted had been found in Japan, which is more than 1000 km from the Tianchi volcanic vent[4,5]. Moreover, this eruption has been recognized in the study of Greenland ice core (GISP2)[6,7]. There have been many studies about eruption products of the Tianchi volcano, which dominantly focused on petrological, geochemical and volcanic eruptive dynamic aspects[8―10]. On…     

Some regularity in the process of re-awakening of andesite and dacite volcanoes: specific features of the 1982 El Chichón volcano,México reactivation

El Chichón volcano is an andesite stratovolcano in southern México. It erupted in March 1982, after about 550 years of quiescence. The 1982 eruption of El Chichón has not been followed by the growth of a lava dome within the newly formed crater. This is rather anomalous since the construction of a new dome after the destruction of an old one is a common process during the eruptions at andesite and dacite volcanoes. To discuss this anomalous aspect of the El Chichón eruption, some regularity in the process of re-awakening of dormant (here defined as a period of quiescence of more than 100 years) andesite and dacite volcanoes are studied based on the seismic activity recorded at the volcanoes Bezymianny, Mount St. Helens, El Chichón, Unzen, Pinatubo and Soufrière Hills. Three stages were identified in the re-awakening activity of these volcanoes: (1) preliminary seismic activity, leading up to the first phreatic explosion; (2) activity between the first and the largest explosions; (3) post-explosion dome-building process. The eruptions were divided into two groups: low-VEI (Volcanic Explosivity Index) and the long duration stage-1 events (Unzen, 1991 and Soufrière Hills volcano, 1995) and high-VEI and the short duration stage-1 events (Bezymianny, 1956; Mount St. Helens, 1980; El Chichón, 1982 and Pinatubo, 1992). The comparative analysis of the seismo-eruptive activity of two eruptions of the second group, the 1980 of Mt. St. Helens and the 1982 of El Chichón, produced an explanation the absence of new dome building during the 1982 eruption of El Chichón volcano. It may be explained in terms of the unusually rapid emission of gas and water from the magmatic and hydrothermal system beneath the volcano during a relatively short sequence of large explosions that could have sharply increased the viscosity of the magma making impossible its exit to the surface.     

SITE EVALUATION AND VOLCANIC HAZARD ASSESSMENT FOR THE NUCLEAR POWER PLANTS OF CHINA

Starting from the 1980's of last century, China has launched the national plan of constructing nuclear power plants along the coastline region in eastern China. Currently, in some of these candidate sites, nuclear facilities have been installed and are in operation, but some other nuclear power plants are still under construction or in site evaluation. In 2012 the Atomic Energy Commission issued the specific guide for volcanic hazards in site evaluation for nuclear installations(IAEA Safety Standards Series No. SSG-21), which was prepared under the IAEA's program for safety standards. It supplements and provides recommendations for meeting the requirements for nuclear installations established in the safety requirements publication on site evaluation for nuclear installations in relation to volcanic hazards. To satisfy the safety standards for volcanic hazard, we follow the IAEA SSG-21 guidelines and develop a simple and practical diffusion program in order to evaluate the potential volcanic hazard caused by tephra fallout from the explosive eruptions. In this practice, we carried out a case study of the active volcanoes in north Hainan Province so as to conduct the probabilistic analysis of the potential volcanic hazard in the surrounding region. The Quaternary volcanism in north Hainan Island, so-called Qiongbei volcanic field is characterized by multi periodic activity, in which the most recent eruption is dated at about 4 000a BP. According to IAEA SSG-21, a capable volcano is one for which both 1)a future eruption or related volcanic event is credible; and 2)such an event has the potential to produce phenomena that may affect a site. Therefore, the Qiongbei volcanic field is capable of producing hazardous phenomena that may reach the potential nuclear power plants around. The input parameters for the simulation of tephra fallout from the future eruption of the Qiongbei volcanic field, such as the size, density and shape of the tephra, the bulk volume and column height, the diffusion parameter P(z), wind direction and intensity, were obtained by field investigation and laboratory analysis. We carried out more than 10000 tephra fallout simulations using a statistical dataset of wind profiles which are obtained from China Meteorological Data Sharing Service System(CMDSSS). Tephra fallout hazard probability maps were constructed for tephra thickness threshold of 1cm. Our results show that the tephra produced by the future large-scale explosive eruption from the Qiongbei volcanic field can affect the area in a range about 250km away from the eruption center. In summary, the current key technical parameters related to volcanic activity and potential hazards in IAEA/SSG-21 guidelines, such as 10Ma volcanic life cycle and 1×10^-7 volcanic disaster screening probability threshold, etc. are based on the volcanic activity characteristics in the volcanic island arc system. In consideration of the relatively low level of volcanic activity compared with volcanic island arc system due to the different tectonic background of volcanism in mainland China, the time scale of volcanic disaster assessment in IAEA SSG-21 guideline is relatively high for volcanoes in mainland China. We suggest that the study of "conceptual model" of volcanic activity should be strengthened in future work to prove that there is no credible potential for future eruptions, so that these volcanoes should be screened out at early stage instead of further evaluation by probabilistic model.     

The identification and diagnostics of active and potentially active volcanic features in the Kuril-Kamchatka island arc and the Commander Islands link of the Aleutian arc

We consider the identification and diagnostics of active and potentially active volcanic features (regional zones of cinder cones, fields sheet volcanism, fields of concentrated multivent extrusive volcanism, calderas, and underwater eruption centers in the sea) in the Kuril-Kamchatka island arc and in the Commander Islands link of the Aleutian island arc, as well as the condition of this region as of late 2007. We have identified and examined three periods in the research of active and potentially active volcanic features in the region: the early (1697–1934), the new (1935–1962), and the most recent, still in progress (1963 until today). We provide a new definition of the term “active volcano,” which is scientifically well-grounded, for the first time here. We present modified (compared with those available until now) catalogs of active and potentially active volcanic forms in Kamchatka and the Kuril Islands. For typical multieruption volcanoes now in phase I (the active) and II (the passive) of their evolution, we provide long-term forecasts of the character and parameters of future eruptions and the associated volcanic hazard.     

云南腾冲马鞍山最后一次喷发的热释光年龄

云南腾冲火山区是我国少数几个近代有火山活动的地区之一,它由多座第四纪火山组成。其中马鞍山是规模较大,可能喷发较晚的一处火山。从马鞍山火山锥附近采集了２个火山岩样品,进行了热释光测年分析。热释光年龄表明马鞍山最后一次大规模的火山喷发发生在全新世,可能距今约２５００～３５００年。