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1.
Mud volcano is a conical sedimentary body formed by high-pressure mud and gas-dominated fluid migrated to the surface through faults and other channels deep underground, which looks like a volcanic cone formed by magma-volcanism. As a product of crustal movement, mud volcano can bring a large amount of valuable information from deep to the surface when erupting. Therefore, mud volcano is called "god-given borehole" with a depth of 7~12km. Mud volcanoes are the result of upthrust of trapped gases released by the pressure in the stratum and also the channel for the upward migration of gases in the earth. The submarine mud volcano is one of the signs of hydrate and the living evidence of hydrate. The Wusu mud volcanoes are located in the northern Tianshan tectonic belt. Since the mud volcamoes locate in the active part of the tectonic belt and are well connected to the underground, their active degree has a good correlation with the seismicity. The earthquake cases studies based on the 7a long real-time macroscopic monitoring data and the more than 3a long geochemical monitoring data of the Wusu mud volcanoes show that in the earthquake cases of MS ≥ 5.0 within the range of 300km around the Wusu mud volcanoes, the abnormal mud gushing quantity obviously increased by macroscopic monitoring before 9 out of 13 earthquakes. The geochemical microcosmic monitoring data showed obvious abnormal changes before 3 out of 6 earthquakes. The anomalous duration from the emergence of the anomaly to the occurrence of the earthquake is mainly of the mid-term(6~12 months). Before the Jinghe MS6.6 earthquake on August 9, 2017, the Wusu mud volcanoes spewed violently and the chemical components showed an obvious high value anomaly. In January 2017, there was a significant increase in the amount of mud spewing in Aiqigou No.1mud volcano and Baiyanggou No.1mud volcano, and one month before the earthquake, there was the phenomenon that mud gushing amount of Aiqigou No.2 mud volcano gradually increased and the volcano was from dormant to active. There were obvious high values appearing before the earthquake in F-and SO42- in the Aiqigou No.1mud volcano and in F-, CO32-, SO42-, Rn(gas), CH4, Ar and N2 in Baiyanggou(No.1 and 2)mud volcanoes. The values of F-, CO32-, SO42-, Ar and N2 showed short-term anomalies, while CH4 and Rn(gas)showed medium term anomalies. Giggenbach triangular diagram (Na-K-Mg) indicates that the water-rock reaction of Baiyanggou mud volcanoes is complete and little disturbed by the outside. The water-rock reaction of the Aiqigou mud volcanoes is still ongoing, which can explain why the precursor anomaly of the chemical components of the Baiyanggou mud volcanoes is more obvious than that of the Aiqigou mud volcanoes. The geothermal reservoir temperature of the study area is estimated by using a cationic (Na-K, K-Mg, Na-K-Ca) geothermometer. The geothermal reservoir temperature of the Wusu mud volcanoes is about 70℃, and the circulation depth is about 3km. In the process of earthquake preparation, the mud carries deep chemical components to the ground surface due to the effect of compression stress(the result of focal mechanism)or the concentration of regional tectonic stress with earthquake preparation; Or the rock strata in or near the seismogenic area are deformed, the depth of liquid circulation will increase, and the water-rock reaction will be accelerated, which will increase the concentration of some ionic components, and the squeezing process will cause a large number of mud to gush out of the ground, carrying geochemical components. Therefore, the gushing quantity and some chemical components of the mud volcanoes were obviously abnormal before the earthquake.  相似文献   

2.
2012年6月30日新源-和静MS6.6地震前后, 北天山泥火山出现了喷溢和地球化学异常变化. 该地震前、 后4天内两次观测了北天山泥火山, 采集了两批温泉和泥火山气体样品, 测定了样品的气体组分和He、 Ne同位素及CH4、 CO2的碳同位素组成. 结果表明, 泥火山发生了同震喷发, 气体排放量增加, 温泉和泥火山气体出现了不同程度的微量气体浓度异常, 独山子泥火山震前出现了3He/4He高值异常. 研究结果有利于确定利用泥火山和温泉监测地震活动的方法和指标.   相似文献   

3.
蒋雨函  高小其  王阳洋  张磊 《地震》2020,40(3):65-82
在系统介绍中国新疆北天山地区和台湾南部地区泥火山研究进展的基础上, 对其地质特征进行了对比分析。结果显示, 北天山和台湾南部地区的泥火山均沿着断裂带分布, 主要位于背斜轴部, 泥火山分布区地层多出露为含泥岩层。对两个地区泥火山喷出物物理特征进行了对比分析, 固体喷发物的矿物成分相似, 如石英、 蒙脱石等; 液体喷出物的泥浆温度与冒泡频率相近, 但最大气泡直径与气体流量有很大差别。又分别对两地区液体、 气体喷出物的化学特征进行了对比分析, 液体喷出物均盐度高; 甲烷是大多数泥火山喷发气体的主要成分, 一些泥火山喷发的气体主要是二氧化碳。区域构造地质和气候条件不同, 导致两地泥火山喷出物存在差异。从现有研究来看, 两地泥火山的喷发都是岩层的孔隙压力增大造成的。两个地区泥火山与当地地震活动之间表现出良好的对应关系。泥火山的地球化学参数可能是地震活动的潜在指标。  相似文献   

4.
中国火山危险性等级与活动性分类   总被引：7，自引：3，他引：4  
介绍了中国大陆全新世活动火山喷发危险性的评价与活动性分类。火山喷发危险性评价是进行火山活动性分类的基础,参照国外火山活动度水平与火山警报等级,根据火山动力背景特征与火山前兆异常特征确定了中国火山喷发危险性评价等级,它们是安全、注意、警惕、警报、危险、灾害、灾难等7级。根据火山活动的危险性,将中国火山的活动性分为4类:1)处于活动状态的火山——长白山天池火山,已经进入扰动期;2)有活动迹象的火山——腾冲火山,仍然处于平静状态,存在潜在的喷发危险;3)有潜在活动可能的火山,包括五大连池、镜泊湖与海口火山,各种地球物理、地球化学观察都处于背景值范围;4)活动性不明的火山  相似文献   

5.
Mud volcano is a kind of structural geological phenomena under certain hydrogeological environment and can bring plenty of valuable information to the ground when it erupts, therefore, many researchers call it as "Heaven granted well" whose depth can be up to 12km. Mud volcanoes in Xinjiang are distributed in the central-west region of North Tianshan, and five of them are representative, namely, Horgus, Dushanzi, Wenquan, Poplar valley, and Sailetike. We tested the gas, fluid and solid components of these mud volcanoes through investigations and studies of topography and geomorphology, geological and hydrogeological conditions, and mud debris characteristics, and preliminary obtained the origin of these mud volcanoes based on geochemical features. Finally, the paper describes briefly that the continuous enchancement of regional crustal tectonic stress can not only give rise to the seismogenesis and earthquake occurrence, but also break the original cycle of mud volcano to bring about significant activity, therefore, the two have a certain homology relationship.  相似文献   

6.
Ground penetrating radar (GPR) survey was conducted in the Wushanting mud volcano field (Yanchao, Kaohsiung) using a 500 MHz antennae, which allowed high-resolution imaging of subsurface structures. Seven GPR reflection characteristics are recognized. Sigmoid GPR reflection patterns resulted from a recent mud lobe deposited above an underlying older mud lobe front. Contorted GPR facies resulted from recent mud flow which encountered obstacles. Subparallel reflections resulted from mud volcano deposits of limited flowability, low velocity and gentle gradient. Hummocky reflection patterns are formed by interfingering of recent mud lobes building onto low land. Disrupted GPR facies were due to lateral breaks of continuity from mud cracks, which, according to field observation, can provide channels for erosion and form deeper erosion gullies. GPR time slices of different depths are rendered as a three-dimensional model. Approximately orbicular GPR reflection characteristics can indicate arcuate stacked mud lobe fronts of different periods. Some depositional models to explain GPR reflection characteristics can be founded upon observations of recent sedimentary phenomena. The models of this study may be applied to paleoenvironments and the depositional evolution of mud volcanoes in similar geological settings.  相似文献   

7.
Ground penetrating radar (GPR) survey was conducted in the Wushanting mud volcano field (Yanchao, Kaohsiung) using a 500 MHz antennae, which allowed high-resolution imaging of subsurface structures. Seven GPR reflection characteristics are recognized. Sigmoid GPR reflection patterns resulted from a recent mud lobe deposited above an underlying older mud lobe front. Contorted GPR facies resulted from recent mud flow which encountered obstacles. Subparallel reflections resulted from mud volcano deposits of limited flowability, low velocity and gentle gradient. Hummocky reflection patterns are formed by interfingering of recent mud lobes building onto low land. Disrupted GPR facies were due to lateral breaks of continuity from mud cracks, which, according to field observation, can provide channels for erosion and form deeper erosion gullies. GPR time slices of different depths are rendered as a three-dimensional model. Approximately orbicular GPR reflection characteristics can indicate arcuate stacked mud lobe fronts of different periods. Some depositional models to explain GPR reflection characteristics can be founded upon observations of recent sedimentary phenomena. The models of this study may be applied to paleoenvironments and the depositional evolution of mud volcanoes in similar geological settings.  相似文献   

8.
2012年6月30日新源-和静Ms6.6地震前后,新疆北天山地区的泥火山及温泉出现了明显的水化学异常。在地震前后4天内,采集了两批泥火山和温泉水样品,测定了泥火山和温泉水样的水化学参数。资料表明,泥火山喷溢水属于低温、弱碱性咸水或盐水,水化类型为CI-Na,来源于储存在封闭构造中并与干旱海相、河湖相沉围岩发生了漫长而复杂水岩作用的大气降水。温泉水为中温、弱碱性SO4·CI-Na型淡水,形成于地表水沿断裂深循环过程中的水岩作用。安集海泥火山出现同震喷溢,震后泥水温度(T)、总矿化度(TDS)、K+、Na+及Ca2+大幅上升;独山子、白杨沟及AM02泥火山为震前喷溢,独山子、白杨沟泥火山表现为T.TDS、EC、Na+、CI的升高和K+、Ca2+、Mg2+的降低;AM02泥火山K+、Mg+明显降低,Ca2+上升达223%。震后沙湾25号泉T降低7℃, TDS、电导率(EC)、K+、Na+、 Ca2+、 .Mg2+、CI-及$SO_{4}^{2-}$升高。研究结果可用于北天山地区的地震趋势分析和改进利用各泥火山、温泉进行北天山地区地震活动性监测的水化学方法。  相似文献   

9.
A largely submarine avalanche amphitheatre that formed catastrophically in 1888 on Ritter volcano has been identified from a bathymetric survey. Collapse of the volcano in 1888 therefore is considered to have been caused by rapid, large-scale slope failure, rather than by cauldron subsidence, as previously supposed. Escarpments of pre-historic slope failures are common on other Papua New Guinea volcanoes. Directions of avalanching on some volcanoes in the Bismarck volcanic arc appear to be controlled by a regional stress pattern, and those for some volcanoes in the Fly-Highlands province on mainland Papua New Guinea point away from the regional centre of Pliocene uplift. Large amphitheatres such as at Doma Peaks in the Fly-High-lands province probably originated by multiple collapses.  相似文献   

10.
梁卉  高小其  向阳  朱成英 《中国地震》2018,34(3):534-544
泥火山形成于特定的水文地质及构造环境,其喷发活动是内部大量气体聚集引起异常高压的一种释放,可以将大量地下信息携带到地表,被称为"天赐钻井"。新疆乌苏艾其沟泥火山实时观测始于2011年8月,自观测以来,在其周围200m范围内,共发生了4次6级以上地震,分别是2011年11月1日新疆尼勒克M_S6.0、2012年6月30日新疆新源M_S6.6、2016年12月8日新疆呼图壁县M_S6.2及2017年8月9日精河M_S6.6地震。在4次地震前后,艾其沟泥火山喷发活动均出现了"背景值—上升—转折—下降—背景值"的宏观异常变化现象,地震则发生在泥火山喷发活动由强到弱的过程中,尤其是在2017年精河M_S6.6地震时,乌苏艾其沟泥火山的喷发活动异常变化现象为新疆地震局做出震情形势判定提供了一部分依据,具有一定的减灾实效。  相似文献   

11.
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。   相似文献   

12.
Cladistics is a systematic method of classification that groups entities on the basis of sharing similar characteristics in the most parsimonious manner. Here cladistics is applied to the classification of volcanoes using a dataset of 59 Quaternary volcanoes and 129 volcanic edifices of the Tohoku region, Northeast Japan. Volcano and edifice characteristics recorded in the database include attributes of volcano size, chemical composition, dominant eruptive products, volcano morphology, dominant landforms, volcano age and eruptive history. Without characteristics related to time the volcanic edifices divide into two groups, with characters related to volcano size, dominant composition and edifice morphology being the most diagnostic. Analysis including time based characteristics yields four groups with a good correlation between these groups and the two groups from the analysis without time for 108 out of 129 volcanic edifices. Thus when characters are slightly changed the volcanoes still form similar groupings. Analysis of the volcanoes both with and without time yields three groups based on compositional, eruptive products and morphological characters. Spatial clusters of volcanic centres have been recognised in the Tohoku region by Tamura et al. (Earth Planet Sci Lett 197:105–106, 2002). The groups identified by cladistic analysis are distributed unevenly between the clusters, indicating a tendency for individual clusters to form similar kinds of volcanoes with distinctive but coherent styles of volcanism. Uneven distribution of volcano types between clusters can be explained by variations in dominant magma compositions through time, which are reflected in eruption products and volcanic landforms. Cladistic analysis can be a useful tool for elucidating dynamic igneous processes that could be applied to other regions and globally. Our exploratory study indicates that cladistics has promise as a method for classifying volcanoes and potentially elucidating dynamic and evolutionary volcanic processes. Cladistics may also have utility in hazards assessment where spatial distributions and robust definitions of a volcano are important, as in locating sensitive facilities such as nuclear reactors and repositories.  相似文献   

13.
Mud volcanoes are common in active mountain fronts. At Mt. Etna, located just between the Apennine front in Sicily and its foredeep, there are some manifestations of mud volcanism in the lower border of the volcanic edifice. The activity of these mud volcanoes is characterized by persistent emission of muddy water mixed with salts, which rises to the surface due to the gas pressure in the subsoil. The San Biagio Salinelle is one of the three mud volcano fields located around the Paternò eruptive monogenic apparatus; this old volcanic structure was one of the first subaerial volcanic manifestations that formed in the pre-Etnean phase. It is not fully clear whether and how the activity of the mud fields is connected with the volcanic activity of Mt. Etna. Noninvasive geophysical surveys were carried out in the area of the active cone of the San Biagio Salinelle, in order to identify the probable ascent path of the emitted products. Seismic ambient noise records were collected at the nodes of a specially designed grid and, subsequently, the V s values were obtained from an active seismic survey. A digital elevation model (DEM) of the area was obtained by a topographic survey, carried out with the GNSS technique (global navigation satellite system), in real-time kinematic mode. The DEM and the topographic benchmark installed will represent the reference surface for future periodic monitoring of the ongoing deformation in the area. Our results provide an accurate and detailed 3D subsurface model showing the shallower feeding system of the investigated mud volcano.  相似文献   

14.
During 1999, the volcanic activity at Mt. Etna was both explosive and effusive at the summit craters: Strombolian activity, lava fountains and lava flows affected different areas of the volcano, involving three of the four summit craters. Results from analysis of the 1999 volcanic tremor features are shown at two different time scales. First, the long-term time variation of the features of the volcanic tremor (including spectral and polarization parameters), during the entire year, was compared with the evolution of the eruptive activity. This approach demonstrated the good agreement between tremor data and observed eruptive activity; the activation of different tremor sources was suggested. Then, a more refined analysis of the volcanic tremor, recorded during 14 lava fountain eruptions, was performed. In particular, a shift of the dominant frequencies towards lower values was noted which corresponds with increasing explosive activity. Similar behaviour in the frequency content has already been observed in other explosive eruptions at Mt. Etna as well as on other volcanoes. This behaviour has been explained in terms of either an increase in the tremor source dimension or a decrease in the sound speed in the magma within the conduit. These results confirm that the volcanic tremor is a powerful tool for better understanding the physical processes controlling explosive eruptions at Mt. Etna volcano.  相似文献   

15.
腾冲火山区剪切波和尾波衰减初步研究   总被引：7，自引：2，他引：5  
用云南腾冲火山地区观测的地震数字化记录进行了尾波和剪切波的衰减测量。用AkiandChouet和Sato单次散射模型获得 5 2秒和 18秒流逝时间尾波的品质因子分别为Qc (f) =5 7×f- 0 94和Qc (f) =2 6×f- 0 95 ,表明地壳上部和地壳上地幔的地震波衰减频率变化率一致。两者均未显示出活火山地区尾波衰减的异常特征。尾波掠过空间椭球的平均半轴 ,前者约为 80km ,大大超出了腾冲火山分布的地理范围 ,后者约为 30km ,在腾冲火山分布的地理范围之内。用尾波规一双台S波振幅比法进一步缩小所用地震波掠过的空间 ,最后获得了S波随频率的衰减有类似于前人报导的活火山地区尾波频率衰减的特征 :相对于低频 (1 5～ 6Hz) ,高频 (6～2 0Hz)的Q- 1s 变化很小。从地表位置看 ,腾冲最年青的全新世的马鞍山和老龟坡火山就在S波掠过范围内 ,打鹰山火山也在近旁。这一结果表明在这三座火山体之下存在低速高衰减体。火山或处于休眠状态 ,或在消亡过程之中。  相似文献   

16.
Maps of the eruptive vents on the active shield volcanoes of Fernandina and Isabela islands, Galapagos, made from aerial photographs, display a distinctive pattern that consists of circumferential eruptive fissures around the summit calderas and radial fissures lower on the flanks. On some volcano flanks either circumferential or radial eruptions have been dominant in recent time. The location of circumferential vents outside the calderas is independent of caldera-related normal faults. The eruptive fissures are the surface expression of dike emplacement, and the dike orientations are interpreted to be controlled by the state of stress in the volcano. Very few subaerial volcanoes display a pattern of fissures similar to that of the Galapagos volcanoes. Some seamounts and shield volcanoes on Mars morphologically resemble the Galapagos volcanoes, but more specific evidence is needed to determine if they also share common structure and eruptive style.  相似文献   

17.
中国大陆火山监测研究进展   总被引：4，自引：2，他引：4  
在过去几年里，长白山天池火山观测到了明显的地震活动增加、地表抬升和膨胀以及多种流体化学异常。地震学研究和形变模拟表明，长白山天池火山近年来的活动可能是由其下方的岩浆活动引起的。1993年以来，腾冲火山出现强烈的水热活动。地球化学参数的变化表明，气体源区的深度逐渐增加。火山区存在的震群活动、部分台站观测到的S波阴影区以及地表的缓慢抬升等，指示火山区存在一个岩浆系统。监测研究结果表明，目前我国大陆其他火山的活动性较弱。  相似文献   

18.
Seventeen post-Miocene strato volcanoes have been identified on Bougainville, the largest island of the Solomon Group. From north-west to south-east, these are the Tore, Balbi, Numa Numa, Billy Mitchell, Bagana, Reini, and Bakanovi volcanoes and the Takuan and Toroka groups of volcanoes: the Taroka group includes Loloru volcano. In addition there are several other post-Miocene volcanoes in northern Bougainville which have not been accurately delineated. Only three of the volcanoes are active or potentially active; these are Bagana, the most active volcano in the Territory of New Guinea, and the dormant Balbi and Loloru volcanoes. The volcanoes are built up of lavas and pyroclastic deposits mostly of andesitic composition, although some dacitic rocks are also present. Modal and chemical analyses show that these rocks belong to the calc-alkaline suite characteristic of orogesic regions.  相似文献   

19.
During the past 500 thousand years, Unzen volcano, an active composite volcano in the Southwest Japan Arc, has erupted lavas and pyroclastic materials of andesite to dacite composition and has developed a volcanotectonic graben. The volcano can be divided into the Older and the Younger Unzen volcanoes. The exposed rocks of the Older Unzen volcano are composed of thick lava flows and pyroclastic deposits dated around 200–300 ka. Drill cores recovered from the basal part of the Older Unzen volcano are dated at 400–500 ka. The volcanic rocks of the Older Unzen exceed 120 km3 in volume. The Younger Unzen volcano is composed of lava domes and pyroclastic deposits, mostly younger than 100 ka. This younger volcanic edifice comprises Nodake, Myokendake, Fugendake, and Mayuyama volcanoes. Nodake, Myokendake and Fugendake volcanoes are 100–70 ka, 30–20 ka, and <20 ka, respectively. Mayuyama volcano formed huge lava domes on the eastern flank of the Unzen composite volcano about 4000 years ago. Total eruptive volume of the Younger Unzen volcano is about 8 km3, and the eruptive production rate is one order of magnitude smaller than that of the Older Unzen volcano.  相似文献   

20.
Continuous seismic monitoring at Martinique since the 1902 eruption of the Montagne Pelée volcano did not detect local earthquakes for the first 70 years. For the only eruption which occurred in this time span in 1929 the seismograph was 20 km away and of a standard type, not particularly suited for the detection of small-scale local seismicity. Improvement of the monitoring array over the last 15 years with the installation of sensors on the volcano itself allowed the detection of signals of local origin which were interpreted as being due to surface sources, such as rockfalls and landslides. Since December 1985 seismic sources in the volcano itself, i.e. small earthquakes at shallow depth, were identified and located with the aid of a temporary upgrading of the array close to these weak sources. Such an onset of local seismicity could not have been detected with previous seismic equipment; such episodes of seismicity in the volcano might have occurred in the past, apparently quiescent history of the volcano as the reinterpretation of seismograms of some events in 1976 would indicate, without evolving to more important volcanic phenomena. For seismographs on volcanoes the constant upgrading of observation capabilities is certainly perferred to a strict continuity of standard observations.  相似文献   

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