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1.
Volcanic glass compositions and tephra layer age are critical for anchoring their sources and correlating among different sites; however, such work may be imprecise when the tephra has varied compositions. The ash from Changbaishan Millennium eruption (940s AD), a widely distributed tephra layer, has been detected in the far-east areas of Russia, the Korean Peninsula, Japan, and in Greenland ice cores. There are some debates on the presence of this tephra from sedimentary archives to the west of Changbaishan volcano, such as lake and peat sediments in the Longgang volcanic field. In this paper, major element compositions for clinopyroxene and Fe-Ti oxides were performed on proximal tephra from Changbaishan and the Millennium eruption ash record in Lake Sihailongwan. Clinopyroxene and Fe-Ti oxides microlites from Sihailongwan show augite- ferroaugite and titanmagnetite compositions, similar to those from dark pumice in Changbaishan proximal tephra, but different from the light grey pumice, which has ferrohedenbergite and ilmenite microlite compositions. This result implies that the tephra recorded in Sihailongwan was mainly from the trachytic eruptive phase of the Millennium eruption, and the rhyolitic eruptive phase made a relatively small contribution to this area. Analyzing clinopyroxene and Fe-Ti oxides microlites is a new method for correlating tephra layers from Changbaishan Millennium eruption. 相似文献
2.
Tephra dispersed during the Millennium eruption (ME), Changbaishan Volcano, NE China provides one of the key stratigraphic links between Asia and Greenland for the synchronization of palaeoenvironmental records. However, controversy surrounds proximal-distal tephra correlations because (a) the proposed proximal correlatives of the distal ME tephra (i.e. B–Tm) lack an unequivocal chronostratigraphic context, and (b) the ME tephra deposits have not been chemically characterized for a full spectrum of element using grain-specific techniques. Here we present grain-specific glass chemistry, including for the first time, single grain trace element data, for a composite proximal sequence and a distal tephra from Lake Kushu, northern Japan (ca. 1100 km away from Changbaishan). We demonstrate a robust proximal-distal correlation and that the Kushu tephra is chemically associated with the ME/B–Tm. We propose that three of the proximal pyroclastic fall units were erupted as part of the ME. The radiocarbon chronology of the Kushu sedimentary record has been utilised to generate a Bayesian age-depth model, providing an age for the Kushu tephra which is consistent with high resolution ages determined for the eruption and therefore supports our geochemical correlation. Two further Bayesian age-depth models were independently constructed each incorporating one of two ice-core derived ages for the B–Tm tephra, providing Bayesian modelled ages of 933–949 and 944–947 cal AD (95.4%) for the Kushu tephra. The high resolution ice-core tephra ages imported into the deposition models help test and ultimately constrain the radiocarbon chronology in this interval of the Lake Kushu sedimentary record. The observed geochemical diversity between proximal and distal ME tephra deposits clearly evidences the interaction of two compositionally distinct magma batches during this caldera forming eruption. 相似文献
3.
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". 相似文献
4.
PRELIMINARY VOLCANIC HAZARD ZONATION IN JINLONGDINGZI VOLCANO,LONGANG VOLCANO AREA,JILIN PROVINCE,CHINA 
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下载免费PDF全文 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. 相似文献
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6.
An extremely large magnitude eruption of the Ebisutoge-Fukuda tephra, close to the Plio-Pleistocene boundary, central Japan, spread volcanic materials widely more than 290,000 km2 reaching more than 300 km from the probable source. Characteristics of the distal air-fall ash (>150 km away from the vent) and proximal pyroclastic deposits are clarified to constrain the eruptive style, history, and magnitude of the Ebisutoge-Fukuda eruption.Eruptive history had five phases. Phase 1 is phreatoplinian eruption producing >105 km3 of volcanic materials. Phases 2 and 3 are plinian eruption and transition to pyroclastic flow. Plinian activity also occurred in phase 4, which ejected conspicuous obsidian fragments to the distal locations. In phase 5, collapse of eruption column triggered by phase 4, generated large pyroclastic flow in all directions and resulted in more than 250–350 km3 of deposits. Thus, the total volume of this tephra amounts over 380–490 km3. This indicates that the Volcanic Explosivity Index (VEI) of the Ebisutoge-Fukuda tephra is greater than 7. The huge thickness of reworked volcaniclastic deposits overlying the fall units also attests to the tremendous volume of eruptive materials of this tephra.Numerous ancient tephra layers with large volume have been reported worldwide, but sources and eruptive history are often unknown and difficult to determine. Comparison of distal air-fall ashes with proximal pyroclastic deposits revealed eruption style, history and magnitude of the Ebisutoge-Fukuda tephra. Hence, recognition of the Ebisutoge-Fukuda tephra, is useful for understanding the volcanic activity during the Pliocene to Pleistocene, is important as a boundary marker bed, and can be used to interpret the global environmental and climatic impact of large magnitude eruptions in the past. 相似文献
7.
We have documented 80 tephra beds dating from ca. 9.5 to >50 ka, contained within continuously deposited palaeolake sediments from Onepoto Basin, a volcanic explosion crater in Auckland, New Zealand. The known sources for distal (>190 km from vent) tephra include the rhyolitic Taupo Volcanic Centre (4) and Okataina Volcanic Centre (14), and the andesitic Taranaki volcano (40) and Tongariro Volcanic Centre (3). The record provides evidence for four new events between ca. 50 and 28 ka (Mangaone Subgroup) suggesting Okataina was more active than previously known. The tephra record also greatly extends the known northern dispersal of other Mangaone Subgroup tephra. Ten rhyolitic tephra pre-date the Rotoehu eruption (>ca. 50 ka), and some are chemically dissimilar to post-50 ka rhyolites. Some of these older tephra were produced by large-magnitude events; however, their source remains uncertain. Eight tephra from the local basaltic Auckland Volcanic Field (AVF) are also identified. Interpolation of sedimentation rates allow us to estimate the timing of 12 major explosive eruptions from Taranaki volcano in the 27.5-9.5-ka period. In addition, 28 older events are recognised. The tephra are trachytic to rhyolitic in composition. All have high K2O contents (>3 wt%), and there are no temporal trends. This contrasts with the proximal lava record that shows a trend of increasing K2O with time. By combining the Onepoto tephra record with that of the previously documented Pukaki crater, 15 AVF basaltic fall events are constrained at: 34.6, 30.9, 29.6, 29.6, 25.7, 25.2, 24.2, 23.8, 19.4, 19.4, 15.8 and 14.5 ka, and three pre-50 ka events. This provides some of the best age constraints for the AVF, and the only reliable data for hazard recurrence calculations. The minimum event frequency of both distal and local fall events can be estimated, and demonstrates the Auckland City region is frequently impacted by ash fall from many volcanoes. 相似文献
8.
Review of eruptive activity at Tianchi volcano, Changbaishan, northeast China: implications for possible future eruptions 总被引：8，自引：0，他引：8
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. 相似文献
9.
The spatial extent of tephra deposition and environmental impacts from the 1912 Novarupta eruption 总被引：1，自引：1，他引：0
The eruption of Novarupta within the Katmai Volcanic Cluster, south-west Alaska, in June 1912 was the most voluminous eruption of the twentieth century but the distal distribution of tephra deposition is inadequately quantified. We present new syntheses of published tephrostratigraphic studies and a large quantity of previously un-investigated historical records. For the first time, we apply a geostatistical technique, indicator kriging, to integrate and interpolate such data. Our results show evidence for tephra deposition across much of Alaska, Yukon, the northern Pacific, western British Columbia and northwestern Washington. The most distal tephra deposition was observed around 2,500?km downwind from the volcano. Associated with tephra deposition are many accounts of acid deposition and consequent impacts on vegetation and human health. Kriging offers several advantages as a means to integrate and present such data. Future eruptions of a scale similar to the 1912 event have the potential to cause widespread disruption. Historical records of tephra deposition extend far beyond the limit of deposition constrained by tephrostratigraphic records. The distal portion of tephra fallout deposits is rarely adequately mapped by tephrostratigraphy alone; contemporaneous reports of fallout can provide important constraints on the extent of impacts following large explosive eruptions. 相似文献
10.
C. Lacasse H. Sigurdsson H. Jóhannesson M. Paterne S. Carey 《Bulletin of Volcanology》1995,57(1):18-32
Geochemical evidence shows that the silicic component of the widespread Ash Zone 1 in the North Atlantic is derived from a major ignimbrite-forming eruption which occurred at the Katla caldera in southern Iceland during the transition from glacial to interglacial conditions in Younger Dryas time. Both trace and major element evidence of the rhyolitic products excludes the Öræfajökull volcano as a source. The high-Ti basaltic component in the marine ash zone can also be attributed to contemporaneous eruption in the Katla volcanic complex. Dispersal of tephra from this event is primarily attributed to the generation of co-ignimbrite ash columns in the atmosphere, with ash fallout on both sea ice and on the ocean floor north and east of Iceland. Owing to the changing ocean circulation characteristics of the glacial regime, including suppression of the Irminger Current and a stronger North Atlantic Current, tephra was rafted on sea ice south into the central North Atlantic and deposited as dispersed Ash Zone 1. Sediments south of Iceland also show evidence of the formation of ash turbidites, generated either by the entrance of pyroclastic flows into the sea, or during discharge of jökulhlaups or glacier bursts from this subglacial eruption. 相似文献
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12.
长白山天池火山潜在喷发危险性讨论 总被引：3，自引：0，他引：3
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。 相似文献
13.
The Changbaishan volcano is an active and considerably hazardous volcano located on the border of China and North Korea. This paper summarizes a series of geophysical surveys as well as seismological and volcano-observational networks around the Changbaishan volcanic area. We characterize deep structures related to the Changbaishan volcanic area. The prominent low-velocity anomalies and low-resistance bodies associated with the magma system under the Changbaishan volcano were detected in the crust and upper mantle, and high-velocity anomalies were imaged within the mantle transition zone,suggesting that the origin of the Changbaishan volcano is related to the subducted Pacific slab. However, there exist a few major obstacles for comprehensively elucidating the deep structure of the Changbaishan volcano as well as for the preparedness for and response toward future volcanic unrest and activity. It is essential to collect data from both China and Korean Peninsula to image the deep structure beneath the Changbaishan volcanic area. A multi-disciplinary approach comprising seismological investigations, deformation information from GNSS and InSar, and gravity and magnetotelluric surveying is a reliable manner for imaging high-resolution structures and fluid movement for the spatial distribution and variation of the volcanic magma chamber.An effective volcano-monitoring network system is considerably important to improve hazard assessments and characterize the potential future eruption of the Changbaishan volcano. 相似文献
14.
Causes and consequences of bimodal grain-size distribution of tephra fall deposited during the August 2006 Tungurahua eruption (Ecuador) 总被引：2，自引：2，他引：0
Julia Eychenne Jean-Luc Le Pennec Liliana Troncoso Mathieu Gouhier Jean-Marie Nedelec 《Bulletin of Volcanology》2012,74(1):187-205
The violent August 16–17, 2006 Tungurahua eruption in Ecuador witnessed the emplacement of numerous scoria flows and the deposition
of a widespread tephra layer west of the volcano. We assess the size of the eruption by determining a bulk tephra volume in
the range 42–57 × 106 m3, which supports a Volcanic Explosivity Index 3 event, consistent with calculated column height of 16–18 km above the vent
and making it the strongest eruptive phase since the volcano’s magmatic reactivation in 1999. Isopachs west of the volcano
are sub-bilobate in shape, while sieve and laser diffraction grain-size analyses of tephra samples reveal strongly bimodal
distributions. Based on a new grain-size deconvolution algorithm and extended sampling area, we propose here a mechanism to
account for the bimodal grain-size distribution. The deconvolution procedure allows us to identify two particle subpopulations
in the deposit with distinct characteristics that indicate dissimilar transport-depositional processes. The log-normal coarse-grained
subpopulation is typical of particles transported downwind by the main volcanic plume. The positively skewed, fine-grained
subpopulation in the tephra fall layer shares close similarities with the elutriated co-pyroclastic flow ash cloud layers
preserved on top of the scoria flow deposits. The area with the higher fine particle content in the tephra layer coincides
with the downwind prolongation of the pyroclastic flow deposits. These results indicate that the bimodal distribution of grain
size in the Tungurahua fall deposit results from synchronous deposition of lapilli from the main plume and fine ash elutriated
from scoria flows emplaced on the western flank of the volcano. Our study also reveals that inappropriate grain-size data
processing may produce misleading determination of eruptive type. 相似文献
15.
O.A. Braitseva I.V. Melekestsev V.V. Ponomareva V.Yu. Kirianov 《Journal of Volcanology and Geothermal Research》1996,70(1-2)
The largest Plinian eruption of our era and the latest caldera-forming eruption in the Kuril-Kamchatka region occurred about cal. A.D. 240 from the Ksudach volcano. This catastrophic explosive eruption was similar in type and characteristics to the 1883 Krakatau event. The volume of material ejected was 18–19 km3 (8 km3 DRE), including 15 km3 of tephra fall and 3–4 km3 of pyroclastic flows. The estimated height of eruptive column is 22–30 km. A collapse caldera resulting from this eruption was 4 × 6.5 km in size with a cavity volume of 6.5–7 km3. Tephra fall was deposited to the north of the volcano and reached more than 1000 km. Pyroclastic flows accompanied by ash-cloud pyroclastic surges extended out to 20 km. The eruption was initially phreatomagmatic and then became rhythmic, with each pulse evolving from pumice falls to pyroclastic flows. Erupted products were dominantly rhyodacite throughout the eruption. During the post-caldera stage, when the Shtyubel cone started to form within the caldera, basaltic-andesite and andesite magma began to effuse. The trigger for the eruption may have been an intrusion of mafic magma into the rhyodacite reservoir. The eruption had substantial environmental impact and may have produced a large acidity peak in the Greenland ice sheet. 相似文献
16.
The eruption of Toba (75,000 years BP), Sumatra, is the largest magnitude eruption documented from the Quaternary. The eruption produced the largest-known caldera the dimensions of which are 100 × 30 km and which is surrounded by rhyolitic ignimbrite covering an area of over 20,000 km2. The associated deep-sea tephra layer is found in piston cores in the north-eastern Indian Ocean covering a minimum area of 5 × 106 km2. We have investigated the thickness, grain size and texture of the Toba deep-sea tephra layer in order to demonstrate the use of deep-sea tephra layers as a volcanological tool. The exceptional magnitude and intensity of the Toba eruption is demonstrated by comparison of these data with the deep-sea tephra layers associated with the eruptions of the Campanian ignimbrite, Italy and of Santorini, Greece in Minoan time. The volume of ignimbrite and distal tephra fall deposit produced in the Toba eruption are comparable, a total of at least 1000 km3 of dense rhyolitic magma. In contrast the volume of dense magma produced by the Campanian and Santorini eruptions are approximately 70 and 13 km3 respectively. Thickness versus distance data on the three deep-sea tephra layers show that eruptions of smaller magnitude than Santorini are unlikely to be preserved as distinct tephra layers in most deep-sea cores. In proximal cores all three tephra layers show two distinct units: a lower coarse-grained unit and an upper fine-grained unit. We interpret the lower unit as a plinian deposit and the upper unit as a co-ignimbrite ash-fall deposit, indicating two major eruptive phases. The Toba tephra layer is coarser both in maximum and median grain size than the Campanian and Santorini layers at a given distance from source. These data are interpreted to indicate a very high cruption column, estimated to be at least 45 km. We have applied a method for estimating the duration of the Toba eruption from the style of graded-bedding in deep-sea tephra layers. Studies of two cores yield estimates of 9 and 14 days. The eruption column height and duration estimates both indicate an average volume discharge rate of approximately 106 m3/sec. The Toba eruption therefore was not only of exceptional magnitude, but also of exceptional intensity. 相似文献
17.
A tephrostratigraphy for Erebus volcano is presented, including tephra composition, stratigraphy, and eruption mechanism. Tephra from Erebus were collected from glacial ice and firn. Scanning electron microscope images of the ash morphologies help determine their eruption mechanisms The tephra resulted mainly from phreatomagmatic eruptions with fewer from Strombolian eruptions. Tephra having mixed phreatomagmatic–Strombolian origins are common. Two tephra deposited on the East Antarctic ice sheet, ~ 200 km from Erebus, resulted from Plinian and phreatomagmatic eruptions. Glass droplets in some tephra indicate that these shards were produced in both phreatomagmatic and Strombolian eruptions. A budding ash morphology results from small spheres quenched during the process of hydrodynamically splitting off from a parent melt globule. Clustered and rare single xenocrystic analcime crystals, undifferentiated zeolites, and clay are likely accidental clasts entrained from a hydrothermal system present prior to eruption. The phonolite compositions of glass shards confirm Erebus volcano as the eruptive source. The glasses show subtle trends in composition, which correlate with stratigraphic position. Trace element analyses of bulk tephra samples show slight differences that reflect varying feldspar contents. 相似文献
18.
利用面波层析成像和远震接收函数方法对长白山地区的地壳上地幔速度结构进行了研究。结果表明:长白山火山区附近存在岩石圈减薄、上地幔软流圈增厚以及上地幔S波速度降低等与上地幔高温物质有关的现象,它表明长白山的岩浆系统一直延伸到上地幔软流圈范围。天池火山区地壳内部存在明显的S波低速层,在离天池火山口较近的WQD台附近,低速层顶部埋深约8km,厚度近20km,S波最小速度约2.2km/s。在距离天池火山北部50km的EDO台地壳中没有明显的低速层。火山区S波速度结构总体表现出距离天池越近,地壳的V_P/V_S越大,低速层的厚度和幅度增加的特征,表明天池火山口附近地壳内部存在高温物质或岩浆囊。CBS台站不同方位的接收函数及反演结果表明,地表低速层厚度以及莫霍面深度存在随方位的变化。地表低速层在南部方向明显较厚,莫霍面深度在南部天池火山口方向存在小幅度抬升。CBS台站附近特殊的近地表速度结构可能是该台站记录的火山地震波形主频较低的主要因素。天池火山口附近莫霍面的小幅度抬升意味着存在与火山作用有关的壳幔物质交换通道 相似文献
19.
Jianping Wu Yuehong Ming Lihua Fang Weilai Wang Institute of Geophysics China Earthquake Administration Beijing China 《地震学报(英文版)》2009,(4):409-416
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 ... 相似文献
20.
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。 相似文献