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.     

基于InSAR、GPS形变场的长白山地区火山岩浆囊参数模拟研究

利用差分合成孔径雷达干涉测量技术（DInSAR）获取长白山地区的形变场.结果显示1995~1998年期间,位于长白山东南侧的间白山火山存在6~12 cm的视线向形变,而长白山天池火山处于平静期,没有明显形变.利用2002~2003年的GPS和水准获取的形变数据,分别采用Mogi单源、双源模型反演了长白山地区火山的岩浆囊参数.其中双源模型拟合效果较为理想,两个点源一个位于长白山天池老火山口下方7.9 km处,另一个位于间白山火山下方5.5 km处.对双源模型反演得到的岩浆囊参数进行适当调整,拟合得到与InSAR形变场基本吻合的结果.上述研究结果表明长白山地区火山活动存在时间上的间歇性和空间上的迁移性,为进一步研究长白山地区火山活动机制提供了参考和依据.     

图们江流域新生代火山岩Sr、Nd同位素初步研究

中国地震局地质研究所; 中国地震局地质研究所 北京     

长白山天池火山一次近代喷发物的特征

长白山天池火山是中国最具有潜在灾害性喷发危险的活动火山。在开展长白山天池火山近代喷发历史的研究中,通过野外考察、粒度分析、岩石化学研究,识别出了一套新的火山喷发物。这套喷发物分布于天池水面东北侧,为一套灰色多层火山碎屑堆积,厚约9.2m。下伏公元1668年的火山空降堆积。粒度分析表明,天池火山最近一次喷发物以空降堆积为主,夹一层薄层涌浪堆积,火山喷发类型为射气岩浆型。涌浪堆积碎屑物的分数维值为2.71。空降堆积的分数维值小于涌浪堆积,综合投点求出的分数维值为2.36。显微镜下可观察到鸡骨架状玻屑,无黏土矿物,为原生火山爆发堆积。火山碎屑堆积物中的浮岩岩石化学分析结果表明岩浆成分为粗面质。根据历史记录、地层层序关系、堆积物特征的综合分析,推测堆积物的形成时间为公元1903年     

长白山天池火山玻璃和长石微观特征研究

研究了长白山天池火山1000年和5000年前2次大喷发产生的浮岩和火山灰的微观特征,通过TEM-EDX和SEM-EDX分析了浮岩中的火山玻璃和长石晶屑的表面特征及风化层厚度。5000年前大喷发浮岩中的火山玻璃风化层平均厚度3·74μm,1000年前大喷发为0·98μm;5000年前大喷发浮岩中的长石表面风化溶蚀度大于1000年前大喷发物中的长石;两次大喷发浮岩中的火山玻璃风化层化学组成与火山玻璃相比富Al和Fe而Si减少。综合上述特征认为,天池火山喷发物中矿物的微观特征的差异与火山喷发年代和喷发环境有关。因此,系统研究天池火山喷发物的微观特征是十分必要的,并且具有一定的应用价值     

长白山火山活动的现状和未来展望

长白山天池火山是中新世以来,特别是中更新世以来多次喷发并造成严重灾害的火山,是一座具有潜在喷发危险性的活动火山,文章主要阐述了全新世和近代火山活动及其喷发物,并对火山的现代活动与未来火山活动及其灾害作了评估。     

长白山天池火山溃湖洪水最大流量的初步估算及影响分析

长白山天池火山是目前最具潜在喷发危险的活火山。依据长白山天池火山的最新监测研究成果,结合地形地貌、水文流域特点及天池火山历史喷发类型,重点分析了长白山天池火山未来喷发时发生溃湖洪水的危险性。利用相关的水动力学公式,建立了溃口规模和洪水湿周、流量和流速的内在关系。详细分析溃湖洪峰在下游二道白河镇、白山水电站、红石水电站等关键位置的最大流量及流速。结果表明,若天池火山湖水溃泄一半即10亿m3时,距火山口50km处的二道白河镇瞬时洪水流速达84 904m3/s,该镇将全部被淹没。下游的白山水库、丰满水库将分别受到流量23 560m3/s和1 505m3/s洪水的冲击,水库安全受到严重威胁。     

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。     

THE HISTORICAL RECORDS OF VOLCANIC ERUPTION IN THE KOREAN PENINSULA

The historical document record is of vital significance to determine the volcanic eruption history age in the volcanology research and it cannot be replaced by ¹⁴C dating and other methods. The volcanoes are widely distributed in the northeast area of China, but there is lack of relevant historical records. However, there are the records of the volcanic eruption in the historical documents of Goryeo Dynasty(AD918-1392)and Joseon Dynasty(AD1391-1910)in the Korean Peninsula which is separated by a river with China only. Some of the records have been widely used as important information to the research of Changbaishan Tianchi volcano eruption history by researchers both at home and abroad, but they have different opinions. On the basis of the historical documents in the Korean Peninsula, that is, the History of Goryeo Dynasty and the Annals of the Joseon Dynasty so on, the phenomena of volcanic eruptions, including the intuitive eruptive events and the doubtful volcanic eruption phenomenon such as "the ash fall", "the white hair fall", "the sky fire", "the dust fall" are investigated and put in order systematically in this paper. The results are as follows:1)The intuitive eruptive events are the 1002AD eruption of Mt. Halla volcano on Jeju Island, Korea Peninsula, and the 1007AD volcanic eruption offshore to the west of Jeju Island, Korea Peninsula, as well as the 1597AD eruption of Mt. Wangtian'e volcano in Changbai County, Jilin Province, China; 2)"The ash fall" is airborne volcanic ash, and those "ash falls" happening in 1265, 1401-1405, 1668, 1673 and 1702AD are possibly the tephra of Changbaishan Tianchi volcano; 3)"The white hair fall" is Pele's hair and it is speculated that the "white hair fall "happening in 1737AD is related to Changbaishan Tianchi volcanic eruption; 4)If regarding "the sky fire" as the volcanic eruption phenomenon, "the sky fire" happening in 1533AD is possibly the Changbaishan volcanic eruption event, and "the sky fire" in 1601-1609AD may be the eruptive event of the Longgang volcano in Jilin Province, China or Changbaishan Tianchi volcano; 5)"The dust fall" is recorded in many historical documents. However, "the dust fall" is not the volcanic ash fall but the phenomenon of loess fall. So, it is improper to determine the eruptive events of Changbaishan Tianchi volcano on the basis of "the dust fall".     

长白山天池火山碎屑流灾害区划

在回顾总结了国外火山碎屑流灾害分析模型研究历史的基础上,本文选取了Flow3D模型对我国东北地区长白山天池火山未来大喷发可能产生的火山碎屑流进行了灾害区域划分。以长白山天池火山现代地形为依据,设定了11条未来爆炸式火山喷发时产生的火山碎屑流的可能流动线路。模拟结果表明,在喷发柱高度为10km的情况下,灾害区划最大半径为13.7km;在喷发柱高度为20km的情况下,灾害区划最大半径为35.4km;在喷发柱高度为30km的情况下,灾害区划最大半径为57.8km。在此基础上,得出了长白山天池火山未来发生中规模、大规模和超大规模火山喷发时火山碎屑流的覆盖范围,完成了我国第一幅长白山天池火山碎屑流灾害区划图。     

THE CHARACTERISTICS OF VOLCANIC ROCKS STRUCTURE AND LITHOFACIES OF DALIUCHONG VOLCANO IN THE TENGCHONG VOLCANIC FIELD,YUNNAN PROVINCE

A set of grey-purple layered volcanic rocks are found widely distributed from the mountain flank to the main peak of Daliuchong volcano, but it's difficult to identify whether they are volcaniclastic rock or lava rock just by field investigation and the crystal structure observation under microscope. The study of matrix microstructure of the volcanic rocks can help to identify the volcanic facies. We recognize the eruptive facies rocks through observation of the matrix microstructure and pore shape with comparison to those of the volcanic vent facies, extrusive facies and effusive facies rocks under microscope, thus the mentioned layered volcanic rocks could be named as dacitic crystal fragment tuff. Combining the joint work of field investigation, systematic sampling, chemical analyzing and microscopic observation, we summary the Daliuchong volcanic facies as follows:1. The effusive facies lava constitutes the base of Daliuchong volcano and was produced by early eruption.2. The explosive facies is composed of dacite crystal fragment welded tuff and volcanic breccia and mainly distributes on the W, S and NE flank of the volcanic cone.3. The volcanic conduit with its diameter more than one hundred meters is located about 100 meters south of the main peak of the Daliuchong volcano.4. The extrusive facies rock is only exposed near the peak of Daliuchong volcano.Therefore, the volcanism of Daliuchong volcano can be speculated as:Large-scale lava overflowing occurred in the early eruption period; then explosive eruptions happened; at last, the volcanisms ceased marked with magma extrusion as lava dome and plug.     

Review of eruptive activity at Tianchi volcano, Changbaishan, northeast China: implications for possible future eruptions

One of the largest explosive eruptions in the past several thousand years occurred at Tianchi volcano, also known as Changbaishan, on the China–North Korea border. This historically active polygenetic central volcano consists of three parts: a lower basaltic shield, an upper trachytic composite cone, and young comendite ash flows. The Millennium Eruption occurred between 938 and 946?ad, and was preceded by two smaller and chemically different rhyolitic pumice deposits. There has been at least one additional, small eruption in the last three centuries. From 2002 to 2005, seismicity, deformation, and the helium and hydrogen gas contents of spring waters all increased markedly, causing regional concern. We attribute this event to magma recharge or volatile exhalation or both at depth, followed by two episodes of addition of magmatic fluids into the overlying aquifer without a phreatic eruption. The estimated present magma accumulation rate is too low by itself to account for the 2002–2005 unrest. The most serious volcanic hazards are ash eruption and flows, and lahars. The available geological information and volcano monitoring data provide a baseline for comprehensive assessment of future episodes of unrest and possible eruptive activity.     

长白山天池火山监测与灾害防御

对吉林省长白山天池火山历史喷发灾害进行了分析,指出了火山灾害可能带来的后果,并根据长白山天池火山现状和火山灾害特点．提出了火山灾害防御对策。     

大兴安岭焰山、高山火山——一种新的火山喷发型式

在野外地质资料基础上,利用火山形态学方法,探讨了大兴安岭焰山、高山火山的喷发型式。结果表明,大兴安岭哈拉哈河-绰尔河火山群中的焰山和高山火山不同于斯通博利式喷发形成的火山,其早期爆破喷发的火山碎屑形成火山渣锥、空降火山碎屑席和小型火山碎屑流,晚期溢出大量熔岩。两火山具有较高大的锥体(标高200～300m以上),在结构上,松散火山砾、火山弹等构成下部的降落锥,熔结集块岩构成上部的溅落锥。由火山砾和火山灰组成的空降火山碎屑席分布在火山锥体周围。两火山溢出的熔岩经历了从结壳熔岩→翻花石→渣状熔岩的演变。根据喷发产物可推断焰山和高山火山具有以下喷发特征:爆破喷发形成持续的喷发柱→斯通博利式喷发→熔岩喷泉喷溢,其中以持续时间较长的喷发柱区别于典型的斯通博利式喷发。类似焰山、高山火山的喷发特征,在龙岗第四纪火山群、镜泊湖全新世火山群中也都有个例,这是中国大陆火山作用中一种新的喷发型式。     

西昆仑阿什火山机构及岩石学、矿物学特征

阿什库勒盆地位于NE向阿尔金断裂与NW向康西瓦断裂的"弧形"交会处,构造活动十分活跃,盆地内发育10余座火山,其中阿什火山为该火山群中最新活动的火山。文中从火山地质、熔岩和斑晶成分、显微结构特征及地质温压计4个方面对阿什火山进行了详细研究。结果表明,阿什火山由火山锥和熔岩流组成,锥体由早期的渣锥和晚期的溅落锥组成,熔岩流分布面积约33km2,可划分为4个流动单元。熔岩属于钾玄岩系列,岩性为粗安岩,显微镜下呈斑状结构。斑晶以长石(主要为中长石)和辉石(包括普通辉石、古铜辉石和紫苏辉石)为主;基质为玻璃质、隐晶质、微晶质,部分含有大量的长石和辉石。斑晶与岩浆的平衡温度为1 104~1 194℃,压力为570~980MPa,对应的岩浆房深度为18.92~32.29km。     

S-wave velocity structure beneath Changbaishan volcano inferred from receiver function

The S wave velocity structure in Changbaishan volcanic region was obtained from teleseismic receiver func-tion modeling. The results show that there exist distinct low velocity layers in crust in volcano area. Beneath WQD station near to the Tianchi caldera the low velocity layer at 8 km depth is 20 km thick with the lowest S-wave velocity about 2.2 km/s. At EDO station located 50 km north of Tianchi caldera,no obvious crustal low velocity layer is detected. In the volcanic re-gion,the thickness of crustal ...     

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.     

petrological and geochemical characteristics of quarternary volcanic rocks in haixing area,eastern north china

Field investigation and lab analysis on samples were carried out for Quaternary volcanoes, including Xiaoshan volcano, Dashan volcano and Bianzhuang hidden volcano, in Haixing area, east of North China. Results show that Xiaoshan volcano with the eruptive material of volcanic scoria, crystal fragments and volcanic ash is a maar volcano, the eruptive pattern is pheatomagmatic eruption, and the influence scope is near the crater. Dashan volcano exploded in the early stage, and then the magma intruded, forming the volcanic neck. The eruption strength and scale are limited, and the eruptive materials are scoria, volcanic agglomerate and dense lava neck. The volcanic rocks in Bianzhuang are porosity and dense volcanic rocks and volcanic breccia, reflecting the pattern of weak explosive eruption and lava flow, and the K-Ar age dating on volcanic rocks indicates that the eruption happened in early Pleistocene. Xiaoshan volcanic scoria and Bianzhuang hidden volcanic rocks are mainly basaltic, Dashan volcanic rocks with lower SiO₂ content are nephelinite in composition. Their oxide contents have no linear relationship, indicating that there is no magma evolution relationship between these magmas from the three places. Three volcanic rocks all have enrichment of light rare earth. The Bianzhuang volcanic rocks are rich in large ion lithophile elements, and have no high field strength elements Zr and Hf, Ti losses. The volcanic materials from Xiaoshan and Dashan are intensively rich in Th, U, Nb and Ta, and significantly poor in K and Ti. Although the magmas from these three places in Haixing area may all come from asthenosphere, the volcanic materials have different petrological and geochemical features, and relatively independent volcanic structures, therefore, they experienced different magma processes.     

2000-2007年期间长白山天池火山区地壳变形监测与分析

自2000年以来,在天池火山区附近布设了由2条精密水准路线、15个GPS测量点构成的地壳形变监测系统。文中详述了该系统的构成,并对近期长白山天池火山区地壳形变资料进行了分析研究。结果表明:2002—2005年,长白山天池火山区地面发生了明显的变形。在垂直方向上,水准路线高差3年累积变化达6.8cm,且越是靠近火山口,变形量越大。在水平方向上,以火山口为中心,各观测点总体位移出现放射状变化,最大可达38cm;山体出现明显的膨胀,最大面膨胀可达6×10-6/a。上述变化于2006年后逐步恢复为正常变化。在此期间,长白山天池火山区火山地震活动频繁,其它监测资料也出现了同步的异常变化。文中分析讨论了引起上述变化的可能原因,认为是天池火山一次最新的岩浆活动所致     

THE VOLCANIC ACTIVITIES AND HAZARD PREDICTION OF WUDALIANCHI VOLCANIC BELT

More than 40 late Cenozoic monogenetic volcanoes formed a volcanic belt striking NNW from Keluo, through Wudalianchi to Erkeshan in NE China. These volcanoes belong to a unified volcano system, namely Wudalianchi volcanic belt(WVB for short). Based on the volcanic evolution history and the nature of monogenetic volcanic system, we estimate that the volcanic system of WVB is still active and has the potential to erupt again. Hence, this paper studied the temporal-spatial distribution and volcanic eruption types to evaluate the possible eruption hazard types and areas of influence in the future. Volcanic field characteristics and K-Ar radiometric data suggest two episodes of volcanism in the WVB, the Pliocene to early Pleistocene volcanism(4.59~1.00MaBP)and the middle Pleistocene to Holocene volcanism(0.79Ma to now). The early episode volcanoes are distributed only in the north of WVB(mainly in Keluo volcanic field), featured by effusive eruption, and mainly formed monogenetic shield, whose base diameter is large and slope is gentle. However, the late episode eruptions occurred over the entire WVB. The explosive eruption in this stage formed numerous relatively intact scoria cones of explosive origin. Meanwhile the effusive eruption formed widely distributed lava flows. Both effusive eruption and explosive eruption are common in WVB. The effusive eruption formed monogenetic shields and lava flows. The resulting pahoehoe lava, aa lava and block lava appeared in WVB. There are three end-member types of explosive eruption driven by magmatic volatile. Violent Strombolian eruption has the highest degree of fragmentation and mass flux, characterized by eruption column. Strombolian eruption has the high degree of fragmentation, but low mass flux, featured by pulse eruption. Hawaiian eruption has low degree of fragmentation, but high in mass flux, generating large scoria cones. In addition, this paper for the first time found phreatomagmatic eruption in WVB, which formed tuff cone. Transitional eruptions are also common in WVB, which have certain characteristics among the end-member eruption types. Besides, certain volcanoes displayed multiple explosive eruption types during the whole eruption span. According to the volcanic temporal-spatial distribution and eruption characteristics in WVB, the potential volcanic hazards in future are constrained. It appears that the violent Strombolian and Strombolian eruption will not have significant impact on aviation safety in the vertical direction. In the radial direction, the ejected volcanic bomb can reach as far as 1km from the vents and the fallout tephra may disperse downwind over a distance ranging from 1~10km. The major hazard of Hawaiian eruption and effusive eruption comes from lava flow, and its migration distance may reach 3.0~13.5km for pahoehoe lava and 2.9~14.9km for aa lava. The base surge in phreatomagmatic eruption can reach a velocity of 200~400m/s, and the migration distance is around 10km. This is a big threat that people should pay more attention to and take precautions in advance. Besides, it is necessary to strengthen the real-time observation of the volcanoes in the WVB, especially those formed in the late episode as well as near the active fault.