Fractures are critical control factors in volcanic reservoirs.Thus,studies on the prediction and distribution patterns of volcanic fractures are crucial for oil and gas exploration and development.Although considerabl...Fractures are critical control factors in volcanic reservoirs.Thus,studies on the prediction and distribution patterns of volcanic fractures are crucial for oil and gas exploration and development.Although considerable research has been conducted on volcanic fractures,targeted research on the spatial distribution patterns of fracture development remains limited in the literature.Two eruption modes,subaqueous eruption and subaerial eruption,have been identified in the Chaganhua subsag of the Songliao Basin,where gas resources have been discovered.Studying the differences in volcanic fracture development is highly important for understanding the law of oil and gas enrichment in volcanic reservoirs.On the basis of thin sections,cores,electrical imaging logs,and other data obtained from boreholes of subaqueous volcanic eruptions in the Songnan fault depression,we describe the characteristics of drilled fractures in detail and use 3D seismic data to extract intrinsic coherence,ant bodies,and Fourier series to extend the azimuthal anisotropic P-wave reflection coefficient,thereby predicting the spatial distribution of fractures at different scales.Moreover,through statistical analysis of quantitative evaluation indicators,such as fracture density and fracture development rate in different drilling wells,combined with the spatial distribution patterns of the predicted fractures,we compared and analyzed the relationships between the distributions of fractures and volcanic institutions,lithology,and volcanic facies.Results indicate that fractures are more developed in volcanic edifices located closer to faults.Considerable differences in fracture development are observed among lithofacies of volcanic rocks.Near faults,effusion facies,explosive facies and external clastic pyroclastic sedimentary subfacies are favorable for fracture development.This research provides a reference for investigating volcanic rock fractures of the same origins worldwide.展开更多
The Mesozoic volcanic rocks of the Bodong Low Uplift in the Bohai Bay Basin have been studied and explored for years.In 2024,the LK7-A well drilled in this region tested high-yield oil and gas flows from volcanic weat...The Mesozoic volcanic rocks of the Bodong Low Uplift in the Bohai Bay Basin have been studied and explored for years.In 2024,the LK7-A well drilled in this region tested high-yield oil and gas flows from volcanic weathered crust.These volcanic rocks need to be further investigated in terms of distribution patterns,conditions for forming high-quality reservoirs,and main factors controlling hydrocarbon accumulation.Based on the logging,geochemical and mineralogical data from wells newly drilled to the Mesozoic volcanic rocks in the basin,and high-resolution 3D seismic data,a comprehensive study was conducted for this area.The research findings are as follows.First,the volcanic rocks in the LK7-A structure are adakites with a large source area depth,and the deep and large faults have provided channels for the emplacement of intermediate-acidic volcanic rocks.Second,volcanic rock reservoirs are mainly distributed in tectonic breccias and intermediate-acidic lavas,and they are dominantly fractured-porous reservoirs,with high-porosity and low-permeability or medium-porosity and low-permeability.Third,the dominant lithologies/lithofacies is the basic condition for forming large-scale volcanic rock reservoirs.Structural fractures and late-stage strong weathering are crucial mechanisms for the formation scale of reservoirs in the Mesozoic volcanic rocks.Fourth,the Bodong Low Uplift exhibits strong hydrocarbon charging by two sags and overpressure mudstone capping,which are favorable for forming high-abundance oil and gas reservoirs.The Mesozoic volcanic buried hills in the study area reflect good trap geometry,providing favorable conditions for large-scale reservoir formation,and also excellent migration and accumulation conditions.Areas with long-term exposure of intermediate-acidic volcanic rocks,particularly in active structural regions,are the key targets for future exploration.展开更多
Tezontle from the Anáhuac Basin became Mexico’s second IUGS Heritage Stone in August 2024.This volcanic scoria of basaltic to basaltic-andesitic composition,once considered a‘providential gift’or a‘divine mat...Tezontle from the Anáhuac Basin became Mexico’s second IUGS Heritage Stone in August 2024.This volcanic scoria of basaltic to basaltic-andesitic composition,once considered a‘providential gift’or a‘divine material’,has been used for over twenty centuries in countless architectural monuments,many of which are included in UNESCO’s World Heritage List.The abundant availability of tezontle in central Mexico,combined with its exceptional physical properties of lightness,hardness,and durability,made it the preferred material for building the massive structures of the monumental Pre-Hispanic City of Teotihuacan(1st-7th centuries).展开更多
The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these a...The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these ashes remain controversial.This study presents the stratigraphic distribution of volcanic ash layers,zircon trace element and Hf isotope data from the Wanhe Section in the southwestern Yangtze Shelf,providing insights into the tectonic setting and the origin of the parent magmas.The results suggest that volcanic ashes in the southwestern Yangtze Shelf primarily originated from arc magmatism in the Wuyi-Yunkai Orogen,with a mixed source from mantle and crust.The findings corroborate the hypothesis that the Late Ordovician–Silurian Wuyi-Yunkai Orogen in South China represents a collisional orogenic belt.展开更多
A prevailing theory suggests that volcanic eruptions triggered environmental changes,which compelled dinosaurs to migrate in search of new habitats.Compelling evidence for this hypothesis has now been discovered in th...A prevailing theory suggests that volcanic eruptions triggered environmental changes,which compelled dinosaurs to migrate in search of new habitats.Compelling evidence for this hypothesis has now been discovered in the Tunxi Basin of eastern China.During the Late Mesozoic,the subduction of the Pacific Plate beneath southeastern China led to multi-stage volcanic activity.The Tunxi Formation in the basin,the first reported Upper Jurassic volcanic unit in the eastern Jiangnan orogen.It overlies the stratum bearing the easternmost mamenchisaurids,which is the dominant Asian sauropod lineage.Geochemical analyses suggest its affinity with coeval magmatism in southeastern China,while new rhyolite zircon U-Pb dating yields an age of 151.6±2.2 Ma,further indicating a transition from arc magmatism to back-arc extension driven by Paleo-Pacific subduction during the Late Jurassic.These studies also confirm that,as early as 156 Ma,the Tunxi Basin was already a key habitat for mamenchisaurids.The Late Jurassic subduction of the Paleo-Pacific Plate caused extensive magmatism across eastern China.This intense tectonic shift likely induced abrupt environmental changes in relative basins.Severe volcanic activity drastically reduced the habitat of mamenchisaurids,prompting a northwestward and southward radiation trend-presents a coherent scene of volcanic eruptions,environmental catastrophe,and dinosaurs migrating.展开更多
The Ning-Wu Basin is an important part of the Middle-Lower Yangtze River Metallogenic Belt in eastern China.It contains well-preserved Mesozoic volcanic sequences that document significant geodynamic evolution.However...The Ning-Wu Basin is an important part of the Middle-Lower Yangtze River Metallogenic Belt in eastern China.It contains well-preserved Mesozoic volcanic sequences that document significant geodynamic evolution.However,uncertainties surrounding the ages of eruptions and the temporal relationships between the four main volcanic cycles—the Longwangshan,Dawangshan,Gushan and Niangniangshan formations—have hindered our understanding of magmatic pulsation and its connection to iron mineralisation.Here,high-precision LA-ICP-MS zircon U-Pb dating of four fresh volcanic samples(one per formation)reveals weighted mean ages of 132.3±1.0 Ma(Longwangshan;MSWD=1.3),130.4±1.6 Ma(Dawangshan;MSWD=1.3),128.1±1.9 Ma(Gushan;MSWD=2.0)and 127.2±1.1 Ma(Niangniangshan;MSWD=0.23).These dates constrain volcanic activity to the Early Cretaceous Valanginian-Hauterivian interval and show a systematic trend of increasingly younger ages spanning~8 Ma(133-125 Ma).This magmatism can be subdivided into three phases:initiation(133-132 Ma),peak activity(132-130 Ma)and cessation(128-125 Ma).The episodic volcanism correlates with the accelerating rollback of the Pacific subduction zone,which drives crustal melting and asthenospheric upwelling.Notably,these cycles supplied the thermal energy,fluids and iron-rich melts that were essential for the formation of porphyritic iron deposits in the basin.By establishing a highresolution chronostratigraphic framework,this study sheds light on the spatiotemporal evolution of the Ning-Wu Basin,elucidating the coupling between crust-mantle dynamics,volcanic cyclicity and ore-forming processes across eastern China’s metallogenic belt.展开更多
Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock struc...Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.展开更多
Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant...Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant lithofacies distribution,particularly the favorable areas for high-quality reservoirs,remains to be determined.In this paper,the Huoshiling Formation in the Dehui faulted depression,Songliao Basin is taken as an example to carry out the multi-scale joint characterization of its pore throat structure,establish a reservoir evaluation standard that considers both the gas content and seepage capacity,and perform reservoir evaluation and play fairway mapping under facies control.The results show that the storage space types of the gas-bearing reservoirs in the faulted depression can be ascribed into three categories and six subcategories according to the pore throat and pore characteristics.In terms of pore sizes,volcaniclastic lava rank the first,followed by volcaniclastic rocks,sedimentary volcaniclastic rocks and volcanic lava.The comprehensive evaluation parameter(Φ·K·Sg,whereΦis porosity,K permeability,and Sggas saturation)of high-quality reservoirs are all greater than 0.1.The volcanic reservoirs in the Stage-III strata are the highest in quality and largest in area of play fairways.The thermal debris flow sub-facies developed at Stage III are mainly seen along the western strike-slip fault zone in the Debei sub-sag and the southwest Nong'an tectonic belt,while those developed at Stage I are distributed along the central and eastern fault zones in the southeastern Baojia sub-sag.The favorable layer evaluation and favorable area delineation under facies control will be of certain reference significance for subsequent exploration and development of volcanic gas reservoirs.展开更多
Volcanic ashes are posing increasingly severer threats to the aviation safety.As the operation temperature of the turbine engine elevates,molten volcanic ash leads to the degradation of the thermal barrier coatings(TB...Volcanic ashes are posing increasingly severer threats to the aviation safety.As the operation temperature of the turbine engine elevates,molten volcanic ash leads to the degradation of the thermal barrier coatings(TBCs)and eventually catastrophic engine failure.However,the physical and chemical properties of volcanic ashes vary due to the distinct chemical compositions,rendering it extremely challenging to evaluate the effects of each ash material on the failure of TBC.Here,we proposed a new metric termed Basicity to investigate the influence of chemical composition on the melting temperature and viscosity of volcanic ashes.Artificial CaO-MgO-Al_(2)O_(3)-SiO_(2) materials(CMAS)were synthesized to simulate the wetting,spreading and corrosion behavior of volcanic ashes at 1300 ℃ on(Gd_(0.9)Yb_(0.1))2Zr_(2)O_(7)(GYbZ),a model TBC material.Our results reveal that the synthetic CMAS does not fully capture the damage caused by volcanic ash due to the difference in compositions.The viscosity and characteristic temperatures decrease as the Basicity value increases,indicating its significant impact on the fusion properties of ashes.Notably,distinct from CMAS,the unexpected presence of Fe_(2)O_(3) in volcanic ashes promotes the formation of garnet phase,conversely impedes the formation of apatite dense layer.These findings provide valuable insights into the corrosion mechanisms caused by TBC and strategies for TBC protection against volcanic ashes.展开更多
The pore structure of rocks significantly influences the porosity and permeability of reservoirs and the migration ability of oil and gas,and being the key task on the development of volcanic gas reservoirs.Nine volca...The pore structure of rocks significantly influences the porosity and permeability of reservoirs and the migration ability of oil and gas,and being the key task on the development of volcanic gas reservoirs.Nine volcanic rock samples from the Yingcheng Formation and Huoshiling Formation in the Longfengshan area of the Changling Fault Depression in the Songliao Basin were selected for this study.The pore structures of the volcanic rocks in the study area were investigated using high-pressure mercury injection,X-ray diffraction combined with fractal theory.The relationships between the fractal dimension and physical properties characteristics,pore structure parameters,and mineral content were analyzed to provide guidance for the development of volcanic rock gas reservoirs.The results show that the reservoir can be divided into 3 types(I,II,and III)based on the shape of the capillary pressure curve,and the physical properties deteriorate successively.Different types of reservoirs exhibit different fractal characteristics.For typesⅠ,ⅡandⅢ,the average total fractal dimensions were 2.3418,2.6850,and 2.9203,respectively.The larger the fractal dimension,the stronger the heterogeneity of reservoir.A small number of macro-pores primarily contributed to permeability.The fractal dimension was negatively correlated with porosity and permeability.The fractal dimension of the rock was strongly correlated with quartz and feldspar contents,and the mineral composition and content are closely related to the pore evolution of the reservoir,which are the internal factors affecting the fractal dimension of volcanic rock.展开更多
Situated in the southwestern Pacific,the Tonga-Kermadec subduction zone is separated into two parts by the Louisvlle Ridge Seamount Chain(LRSC),i.e.,the Tanga subduction zone and the Kermadec subduction zone.Known for...Situated in the southwestern Pacific,the Tonga-Kermadec subduction zone is separated into two parts by the Louisvlle Ridge Seamount Chain(LRSC),i.e.,the Tanga subduction zone and the Kermadec subduction zone.Known for its vigorous volcanic activity,frequent large earthquakes,rapid plate subduction,and distinctive subducting plate morphology,this subduction zone provides valuable insights into its structures,dynamics,and associated geohazards.This study compiles geological and geophysical datasets in this region,including seismicity,focal mechanisms,seismic reflection and refraction profiles,and seismic tomography,to understand the relationship between lithospheric structures of the subduction system and associated seismicity-volcanic activities.Our analysis suggests that variations in overlying sediment thickness,subduction rate,and subduction angle significantly influence the lithospheric deformation processes within the Tonga-Kermadec subduction system.Furthermore,these factors contribute to the notable differences in seismicity and volcanism observed between the Tonga subduction zone and the Kermadec subduction zone.This study enhances our understanding of plate tectonics by providing insights into the interplay between subduction dynamics and lithospheric deformation,which are crucial for analyzing geological and geophysical behaviors in similar subduction environments.展开更多
Permian Kaipaileicike （开派雷兹克） volcanic rocks approximately 0-200 m thick are drilled in the Tahe （塔河） field. The distribution of volcanic rocks and their potential to form hydrocarbon reservoirs are discuss...Permian Kaipaileicike （开派雷兹克） volcanic rocks approximately 0-200 m thick are drilled in the Tahe （塔河） field. The distribution of volcanic rocks and their potential to form hydrocarbon reservoirs are discussed based on the integrated interpretation of log and 3D seismic data. The volcanic rocks, mainly consisting of dacites and basalts, are sandwiched between the Lower Triassic and Lower Carboniferous and bounded by top and bottom unconformities. The dacites accumulated in a mound shape around volcanic craters, whereas the basalts are deposited in tabular or trough-fill ge- ometries. Permian volcanic craters mainly located at the northwest corner of the Tahe field are identi- fied from volcanic rock thickening, occurrence of volcanic breccias, structural arch of the top Permian, seismic attribute anomalies, and fault （piercing conduit） reflections. Along the northwest wing of a Carboniferous salt dome, a stratigraphic trap is formed by a northeast updip pinch-out of Permian volcanic rock. Oil indications within the trap are found in numerous wells. The reservoir volcanic rocks are mainly of the fracture-pore pattern and covered by the caprock of a Lower Triassic mudstone. The hydrocarbon reservoir, which can potentially be a medium-sized oil pool, is connected to Camhrian-Ordovician source rocks through normal faults along the salt dome boundary.展开更多
Taking member one of Yingcheng Formation of Cretaceous in Xudong area, Xushen Gas Field of Songliao Basin for an example and aimed at the diachronous problem generally existed in vol- canic reservoir division, firstly...Taking member one of Yingcheng Formation of Cretaceous in Xudong area, Xushen Gas Field of Songliao Basin for an example and aimed at the diachronous problem generally existed in vol- canic reservoir division, firstly advanced the method of two steps and two unites in the researches of volcanic reservoir finely division that guided by the method that sources controlled and founded the stratigraphic trellis. In this process, volcanic edifices and bodies were identified and traced. The results indicated that aimed strata in study areas could be carved up to six layers of YCII1, YCII2, YCII-II, YCIIlI, YCIII2 and YCIIII from the top to the bottom. Analyzing causes and firmly united of well data and seismic data could achieve fine stratigraphic division of volcanic reservoir. Surfaces of layers and volcanic bodies were basically unanimous in side direction. Stratum inclination gradually reduced with the distances increased from craters. The results of volcanic reservoir division had preferable con- sistency with lithologies and volcanic lithofacies and dynamic development data. The researches offered a useful method to stratigraphic division of volcanic reservoir and it had very important significance to effective development of volcanic reservoir in practice.展开更多
A large number of seismic records are discovered for the first time in the historical materials about Wudalianchi volcanic group eruption in 1720~1721, which provides us with abundant volcanic earthquake information. ...A large number of seismic records are discovered for the first time in the historical materials about Wudalianchi volcanic group eruption in 1720~1721, which provides us with abundant volcanic earthquake information. Based on the written records, the relationship between earthquake and volcanic eruption is discussed in the paper. Fur-thermore it is pointed that earthquake swarm is an important indication of volcanic eruption. Therefore, monitoring volcanic earthquakes is of great significance for forecasting volcanic eruption.展开更多
The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data a...The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic rocks.These rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and basanites.New age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 Ma.The alkaline volcanism is younger,with ages ranging from10 to 4.5 Ma.Magmatic evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing phase.All the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic lavas.Alkaline lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional lavas.Low La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the crust.They cannot be used for discussing the mantle source of the volcanic rocks from this series.Trace elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle sources.Transitional magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic composition.This mantle source is present in all the oldest lavas from the CVL.Alkaline magmas formed from an HIMU-like mantle source,different from the Mt Cameroon HIMU mantle source.The depleted asthenospheric mantle is not involved in the Bafoussam magmatism and the two mantle sources are probably located in the lithospheric mantle,in agreement with recent geophysical models presenting the CVL as a consequence of the partial melting of the lithospheric mantle in response to edge convection along the margin of the Congo craton.展开更多
Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral...Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral contents. Based on the QAPF classification scheme given by IUGS, we propose a method to determine the mineral contents of volcanic rocks using log data and a genetic algorithm. According to the QAPF scheme, minerals in volcanic rocks are divided into five groups： Q（quartz）, A （Alkaline feldspar）, P （plagioclase）, M （mafic） and F （feldspathoid）. We propose a model called QAPM including porosity for the volumetric analysis of reservoirs. The log response equations for density, apparent neutron porosity, transit time, gamma ray and volume photoelectrical cross section index were first established with the mineral parameters obtained from the Schlumberger handbook of log mineral parameters. Then the volumes of the four minerals in the matrix were calculated using the genetic algorithm （GA）. The calculated porosity, based on the interpretation parameters, can be compared with core porosity, and the rock names given in the paper based on QAPF classification according to the four mineral contents are compatible with those from the chemical analysis of the core samples.展开更多
The discovery of the Tazhong-47 oilfield confirmed that it is realistic to explore oil and gas fields around igneous rocks in the Tarim basin. The favorable conditions for petroleum accumulation due to volcanic activ...The discovery of the Tazhong-47 oilfield confirmed that it is realistic to explore oil and gas fields around igneous rocks in the Tarim basin. The favorable conditions for petroleum accumulation due to volcanic activity and igneous rocks formed during the activity show in two aspects. A) The contact surface of igneous rocks and the surrounding sedimentary rocks, like a vertical unconformity surface, formed the conduit of petroleum migration. Petroleum would accumulate once it encountered a trap in which the reservoir had fine porosity and permeability. B) It formed a trap barriered by igneous rocks, or changed or cut the original trap. In addition, volcanic rocks are a kind of potential reservoir, there are many such examples in the world, and oil also shows in the Permian igneous rocks in well Zhong-1 on Tazhong uplift. Petroleum accumulation associated with volcanic activity will be a new exploring field in the Tarim basin.展开更多
Unlike previous theories with velocity and/or elastic modulus averaging, we use a three-phase porous rock physics model developed by Santos for analyzing the seismic response of two immiscible fluids in saturated poro...Unlike previous theories with velocity and/or elastic modulus averaging, we use a three-phase porous rock physics model developed by Santos for analyzing the seismic response of two immiscible fluids in saturated porous media. Considering reservoir reference pressure and coupling drag of two fluids in pores, the effects of frequency, porosity, and gas saturation on the phase velocities of the P-and S-waves are discussed in detail under field conditions. The effects of porosity and gas saturation on Vp/Vs are also provided. The data for our numerical experiments are from a sample of deep volcanic rock from Daqing. The numerical results show that the frequency dispersion effect can be ignored for deep volcanic rocks with low porosity and low permeability. It is concluded that for deep volcanic rocks the effect of gas content in pores on Vp/Vs is negligible but the effect of porosity is significant when there is a certain amount of water contained in the pores. The accurate estimate of lithology and porosity in this case is relatively more important.展开更多
The Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management(G-EVER)Consortium among the Asia-Pacific geohazard research institutes was established in 2012 with the main objective of reducing the ri...The Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management(G-EVER)Consortium among the Asia-Pacific geohazard research institutes was established in 2012 with the main objective of reducing the risk caused by earthquakes,tsunamis and volcanic eruptions worldwide.The first G-EVER workshop was held in Tsukuba,Japan in February 2012.The G-EVER1 accord was approved by the workshop participants which made 10 recommendations that focused on the enhancement of collaboration,sharing of resources and making information about the risks of earthquakes and volcanic eruptions freely available and understandable.展开更多
The Barren Island volcano in the Western Sunda Arc has displayed explosive Strombolian eruptions for more than two decades.This recent explosive event,together with the historic and prehistoric volcanic landforms,pres...The Barren Island volcano in the Western Sunda Arc has displayed explosive Strombolian eruptions for more than two decades.This recent explosive event,together with the historic and prehistoric volcanic landforms,present reliable information about explosive Strombolian eruptions and the volcanological evolution of the Barren Island volcano.This study is a re-evaluation of existing knowledge and incorporates new information and interpretations of the recent and past volcanic activity on Barren Island.Direct observations of explosive eruptions since 1991 showed discrete events of bursting and ballistic transport of blocks and formation of sustained ash plumes,indicating Strombolian and violent Strombolian eruptions.展开更多
基金supported by General Projects of the Natural Science Foundation of China(41972313)major projects of the Natural Science Foundation of China(41790453)。
文摘Fractures are critical control factors in volcanic reservoirs.Thus,studies on the prediction and distribution patterns of volcanic fractures are crucial for oil and gas exploration and development.Although considerable research has been conducted on volcanic fractures,targeted research on the spatial distribution patterns of fracture development remains limited in the literature.Two eruption modes,subaqueous eruption and subaerial eruption,have been identified in the Chaganhua subsag of the Songliao Basin,where gas resources have been discovered.Studying the differences in volcanic fracture development is highly important for understanding the law of oil and gas enrichment in volcanic reservoirs.On the basis of thin sections,cores,electrical imaging logs,and other data obtained from boreholes of subaqueous volcanic eruptions in the Songnan fault depression,we describe the characteristics of drilled fractures in detail and use 3D seismic data to extract intrinsic coherence,ant bodies,and Fourier series to extend the azimuthal anisotropic P-wave reflection coefficient,thereby predicting the spatial distribution of fractures at different scales.Moreover,through statistical analysis of quantitative evaluation indicators,such as fracture density and fracture development rate in different drilling wells,combined with the spatial distribution patterns of the predicted fractures,we compared and analyzed the relationships between the distributions of fractures and volcanic institutions,lithology,and volcanic facies.Results indicate that fractures are more developed in volcanic edifices located closer to faults.Considerable differences in fracture development are observed among lithofacies of volcanic rocks.Near faults,effusion facies,explosive facies and external clastic pyroclastic sedimentary subfacies are favorable for fracture development.This research provides a reference for investigating volcanic rock fractures of the same origins worldwide.
基金Supported by the the National Natural Science Foundation of China(U24B2017)。
文摘The Mesozoic volcanic rocks of the Bodong Low Uplift in the Bohai Bay Basin have been studied and explored for years.In 2024,the LK7-A well drilled in this region tested high-yield oil and gas flows from volcanic weathered crust.These volcanic rocks need to be further investigated in terms of distribution patterns,conditions for forming high-quality reservoirs,and main factors controlling hydrocarbon accumulation.Based on the logging,geochemical and mineralogical data from wells newly drilled to the Mesozoic volcanic rocks in the basin,and high-resolution 3D seismic data,a comprehensive study was conducted for this area.The research findings are as follows.First,the volcanic rocks in the LK7-A structure are adakites with a large source area depth,and the deep and large faults have provided channels for the emplacement of intermediate-acidic volcanic rocks.Second,volcanic rock reservoirs are mainly distributed in tectonic breccias and intermediate-acidic lavas,and they are dominantly fractured-porous reservoirs,with high-porosity and low-permeability or medium-porosity and low-permeability.Third,the dominant lithologies/lithofacies is the basic condition for forming large-scale volcanic rock reservoirs.Structural fractures and late-stage strong weathering are crucial mechanisms for the formation scale of reservoirs in the Mesozoic volcanic rocks.Fourth,the Bodong Low Uplift exhibits strong hydrocarbon charging by two sags and overpressure mudstone capping,which are favorable for forming high-abundance oil and gas reservoirs.The Mesozoic volcanic buried hills in the study area reflect good trap geometry,providing favorable conditions for large-scale reservoir formation,and also excellent migration and accumulation conditions.Areas with long-term exposure of intermediate-acidic volcanic rocks,particularly in active structural regions,are the key targets for future exploration.
文摘Tezontle from the Anáhuac Basin became Mexico’s second IUGS Heritage Stone in August 2024.This volcanic scoria of basaltic to basaltic-andesitic composition,once considered a‘providential gift’or a‘divine material’,has been used for over twenty centuries in countless architectural monuments,many of which are included in UNESCO’s World Heritage List.The abundant availability of tezontle in central Mexico,combined with its exceptional physical properties of lightness,hardness,and durability,made it the preferred material for building the massive structures of the monumental Pre-Hispanic City of Teotihuacan(1st-7th centuries).
基金funded by the National Natural Science Foundation of China(Nos.42222209 and 42488201)the State Scholarship Fund.
文摘The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these ashes remain controversial.This study presents the stratigraphic distribution of volcanic ash layers,zircon trace element and Hf isotope data from the Wanhe Section in the southwestern Yangtze Shelf,providing insights into the tectonic setting and the origin of the parent magmas.The results suggest that volcanic ashes in the southwestern Yangtze Shelf primarily originated from arc magmatism in the Wuyi-Yunkai Orogen,with a mixed source from mantle and crust.The findings corroborate the hypothesis that the Late Ordovician–Silurian Wuyi-Yunkai Orogen in South China represents a collisional orogenic belt.
基金supported by the China Geological Survey(DD20230221)the National Natural Science Foundation of China(42102018)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB26000000).
文摘A prevailing theory suggests that volcanic eruptions triggered environmental changes,which compelled dinosaurs to migrate in search of new habitats.Compelling evidence for this hypothesis has now been discovered in the Tunxi Basin of eastern China.During the Late Mesozoic,the subduction of the Pacific Plate beneath southeastern China led to multi-stage volcanic activity.The Tunxi Formation in the basin,the first reported Upper Jurassic volcanic unit in the eastern Jiangnan orogen.It overlies the stratum bearing the easternmost mamenchisaurids,which is the dominant Asian sauropod lineage.Geochemical analyses suggest its affinity with coeval magmatism in southeastern China,while new rhyolite zircon U-Pb dating yields an age of 151.6±2.2 Ma,further indicating a transition from arc magmatism to back-arc extension driven by Paleo-Pacific subduction during the Late Jurassic.These studies also confirm that,as early as 156 Ma,the Tunxi Basin was already a key habitat for mamenchisaurids.The Late Jurassic subduction of the Paleo-Pacific Plate caused extensive magmatism across eastern China.This intense tectonic shift likely induced abrupt environmental changes in relative basins.Severe volcanic activity drastically reduced the habitat of mamenchisaurids,prompting a northwestward and southward radiation trend-presents a coherent scene of volcanic eruptions,environmental catastrophe,and dinosaurs migrating.
基金supported by The Special Funds for Natural Resource Development in Jiangsu Province(2200113-35)The Central Financial Geological Survey Project of the China Geological Survey(DD20230800702).
文摘The Ning-Wu Basin is an important part of the Middle-Lower Yangtze River Metallogenic Belt in eastern China.It contains well-preserved Mesozoic volcanic sequences that document significant geodynamic evolution.However,uncertainties surrounding the ages of eruptions and the temporal relationships between the four main volcanic cycles—the Longwangshan,Dawangshan,Gushan and Niangniangshan formations—have hindered our understanding of magmatic pulsation and its connection to iron mineralisation.Here,high-precision LA-ICP-MS zircon U-Pb dating of four fresh volcanic samples(one per formation)reveals weighted mean ages of 132.3±1.0 Ma(Longwangshan;MSWD=1.3),130.4±1.6 Ma(Dawangshan;MSWD=1.3),128.1±1.9 Ma(Gushan;MSWD=2.0)and 127.2±1.1 Ma(Niangniangshan;MSWD=0.23).These dates constrain volcanic activity to the Early Cretaceous Valanginian-Hauterivian interval and show a systematic trend of increasingly younger ages spanning~8 Ma(133-125 Ma).This magmatism can be subdivided into three phases:initiation(133-132 Ma),peak activity(132-130 Ma)and cessation(128-125 Ma).The episodic volcanism correlates with the accelerating rollback of the Pacific subduction zone,which drives crustal melting and asthenospheric upwelling.Notably,these cycles supplied the thermal energy,fluids and iron-rich melts that were essential for the formation of porphyritic iron deposits in the basin.By establishing a highresolution chronostratigraphic framework,this study sheds light on the spatiotemporal evolution of the Ning-Wu Basin,elucidating the coupling between crust-mantle dynamics,volcanic cyclicity and ore-forming processes across eastern China’s metallogenic belt.
文摘Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.
基金funded by the National Natural Science Foundation of China(No.42172145)Natural Science Foundation of Heilongjiang Provincial(No.LH2022D014)。
文摘Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant lithofacies distribution,particularly the favorable areas for high-quality reservoirs,remains to be determined.In this paper,the Huoshiling Formation in the Dehui faulted depression,Songliao Basin is taken as an example to carry out the multi-scale joint characterization of its pore throat structure,establish a reservoir evaluation standard that considers both the gas content and seepage capacity,and perform reservoir evaluation and play fairway mapping under facies control.The results show that the storage space types of the gas-bearing reservoirs in the faulted depression can be ascribed into three categories and six subcategories according to the pore throat and pore characteristics.In terms of pore sizes,volcaniclastic lava rank the first,followed by volcaniclastic rocks,sedimentary volcaniclastic rocks and volcanic lava.The comprehensive evaluation parameter(Φ·K·Sg,whereΦis porosity,K permeability,and Sggas saturation)of high-quality reservoirs are all greater than 0.1.The volcanic reservoirs in the Stage-III strata are the highest in quality and largest in area of play fairways.The thermal debris flow sub-facies developed at Stage III are mainly seen along the western strike-slip fault zone in the Debei sub-sag and the southwest Nong'an tectonic belt,while those developed at Stage I are distributed along the central and eastern fault zones in the southeastern Baojia sub-sag.The favorable layer evaluation and favorable area delineation under facies control will be of certain reference significance for subsequent exploration and development of volcanic gas reservoirs.
基金financially supported by the Nature Science Foun-dations of China(NSFC)(Nos.52401071 andU21B2052)China National Postdoctoral Program for Innovative Talents(No.BX20240459).
文摘Volcanic ashes are posing increasingly severer threats to the aviation safety.As the operation temperature of the turbine engine elevates,molten volcanic ash leads to the degradation of the thermal barrier coatings(TBCs)and eventually catastrophic engine failure.However,the physical and chemical properties of volcanic ashes vary due to the distinct chemical compositions,rendering it extremely challenging to evaluate the effects of each ash material on the failure of TBC.Here,we proposed a new metric termed Basicity to investigate the influence of chemical composition on the melting temperature and viscosity of volcanic ashes.Artificial CaO-MgO-Al_(2)O_(3)-SiO_(2) materials(CMAS)were synthesized to simulate the wetting,spreading and corrosion behavior of volcanic ashes at 1300 ℃ on(Gd_(0.9)Yb_(0.1))2Zr_(2)O_(7)(GYbZ),a model TBC material.Our results reveal that the synthetic CMAS does not fully capture the damage caused by volcanic ash due to the difference in compositions.The viscosity and characteristic temperatures decrease as the Basicity value increases,indicating its significant impact on the fusion properties of ashes.Notably,distinct from CMAS,the unexpected presence of Fe_(2)O_(3) in volcanic ashes promotes the formation of garnet phase,conversely impedes the formation of apatite dense layer.These findings provide valuable insights into the corrosion mechanisms caused by TBC and strategies for TBC protection against volcanic ashes.
基金Supported by Key Scientific and Technological Projects of Sinopec(No.P21104-2).
文摘The pore structure of rocks significantly influences the porosity and permeability of reservoirs and the migration ability of oil and gas,and being the key task on the development of volcanic gas reservoirs.Nine volcanic rock samples from the Yingcheng Formation and Huoshiling Formation in the Longfengshan area of the Changling Fault Depression in the Songliao Basin were selected for this study.The pore structures of the volcanic rocks in the study area were investigated using high-pressure mercury injection,X-ray diffraction combined with fractal theory.The relationships between the fractal dimension and physical properties characteristics,pore structure parameters,and mineral content were analyzed to provide guidance for the development of volcanic rock gas reservoirs.The results show that the reservoir can be divided into 3 types(I,II,and III)based on the shape of the capillary pressure curve,and the physical properties deteriorate successively.Different types of reservoirs exhibit different fractal characteristics.For typesⅠ,ⅡandⅢ,the average total fractal dimensions were 2.3418,2.6850,and 2.9203,respectively.The larger the fractal dimension,the stronger the heterogeneity of reservoir.A small number of macro-pores primarily contributed to permeability.The fractal dimension was negatively correlated with porosity and permeability.The fractal dimension of the rock was strongly correlated with quartz and feldspar contents,and the mineral composition and content are closely related to the pore evolution of the reservoir,which are the internal factors affecting the fractal dimension of volcanic rock.
基金supported by Special Projects in Universities’Key Fields of Guangdong Province(No.2023ZDZX3017)the 2022 Tertiary Education Scientific Research Project of Guangzhou Municipal Education Bureau(No.202234607)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2025A1515012983)the National Natural Science Foundation of China(Nos.52371059 and 52101358).
文摘Situated in the southwestern Pacific,the Tonga-Kermadec subduction zone is separated into two parts by the Louisvlle Ridge Seamount Chain(LRSC),i.e.,the Tanga subduction zone and the Kermadec subduction zone.Known for its vigorous volcanic activity,frequent large earthquakes,rapid plate subduction,and distinctive subducting plate morphology,this subduction zone provides valuable insights into its structures,dynamics,and associated geohazards.This study compiles geological and geophysical datasets in this region,including seismicity,focal mechanisms,seismic reflection and refraction profiles,and seismic tomography,to understand the relationship between lithospheric structures of the subduction system and associated seismicity-volcanic activities.Our analysis suggests that variations in overlying sediment thickness,subduction rate,and subduction angle significantly influence the lithospheric deformation processes within the Tonga-Kermadec subduction system.Furthermore,these factors contribute to the notable differences in seismicity and volcanism observed between the Tonga subduction zone and the Kermadec subduction zone.This study enhances our understanding of plate tectonics by providing insights into the interplay between subduction dynamics and lithospheric deformation,which are crucial for analyzing geological and geophysical behaviors in similar subduction environments.
基金supported by the SINOPEC Forward Looking Project (No. YPH08114)the National Key Project of China(No. 2011zx05001-003)
文摘Permian Kaipaileicike （开派雷兹克） volcanic rocks approximately 0-200 m thick are drilled in the Tahe （塔河） field. The distribution of volcanic rocks and their potential to form hydrocarbon reservoirs are discussed based on the integrated interpretation of log and 3D seismic data. The volcanic rocks, mainly consisting of dacites and basalts, are sandwiched between the Lower Triassic and Lower Carboniferous and bounded by top and bottom unconformities. The dacites accumulated in a mound shape around volcanic craters, whereas the basalts are deposited in tabular or trough-fill ge- ometries. Permian volcanic craters mainly located at the northwest corner of the Tahe field are identi- fied from volcanic rock thickening, occurrence of volcanic breccias, structural arch of the top Permian, seismic attribute anomalies, and fault （piercing conduit） reflections. Along the northwest wing of a Carboniferous salt dome, a stratigraphic trap is formed by a northeast updip pinch-out of Permian volcanic rock. Oil indications within the trap are found in numerous wells. The reservoir volcanic rocks are mainly of the fracture-pore pattern and covered by the caprock of a Lower Triassic mudstone. The hydrocarbon reservoir, which can potentially be a medium-sized oil pool, is connected to Camhrian-Ordovician source rocks through normal faults along the salt dome boundary.
基金sponsored by the Magnitude Project of Ministry of Science and Technology of China (No. 2008ZX05016-001)the China Postdoctoral Science Foundation (No. 20100480344)Youth Innovation Fund of Research Institute of Petroleum Exploration and Development of PetroChina (No. 2009-B-10-03)
文摘Taking member one of Yingcheng Formation of Cretaceous in Xudong area, Xushen Gas Field of Songliao Basin for an example and aimed at the diachronous problem generally existed in vol- canic reservoir division, firstly advanced the method of two steps and two unites in the researches of volcanic reservoir finely division that guided by the method that sources controlled and founded the stratigraphic trellis. In this process, volcanic edifices and bodies were identified and traced. The results indicated that aimed strata in study areas could be carved up to six layers of YCII1, YCII2, YCII-II, YCIIlI, YCIII2 and YCIIII from the top to the bottom. Analyzing causes and firmly united of well data and seismic data could achieve fine stratigraphic division of volcanic reservoir. Surfaces of layers and volcanic bodies were basically unanimous in side direction. Stratum inclination gradually reduced with the distances increased from craters. The results of volcanic reservoir division had preferable con- sistency with lithologies and volcanic lithofacies and dynamic development data. The researches offered a useful method to stratigraphic division of volcanic reservoir and it had very important significance to effective development of volcanic reservoir in practice.
文摘A large number of seismic records are discovered for the first time in the historical materials about Wudalianchi volcanic group eruption in 1720~1721, which provides us with abundant volcanic earthquake information. Based on the written records, the relationship between earthquake and volcanic eruption is discussed in the paper. Fur-thermore it is pointed that earthquake swarm is an important indication of volcanic eruption. Therefore, monitoring volcanic earthquakes is of great significance for forecasting volcanic eruption.
文摘The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic rocks.These rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and basanites.New age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 Ma.The alkaline volcanism is younger,with ages ranging from10 to 4.5 Ma.Magmatic evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing phase.All the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic lavas.Alkaline lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional lavas.Low La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the crust.They cannot be used for discussing the mantle source of the volcanic rocks from this series.Trace elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle sources.Transitional magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic composition.This mantle source is present in all the oldest lavas from the CVL.Alkaline magmas formed from an HIMU-like mantle source,different from the Mt Cameroon HIMU mantle source.The depleted asthenospheric mantle is not involved in the Bafoussam magmatism and the two mantle sources are probably located in the lithospheric mantle,in agreement with recent geophysical models presenting the CVL as a consequence of the partial melting of the lithospheric mantle in response to edge convection along the margin of the Congo craton.
基金National Natural Science Foundation of China (No. 49894194-4)
文摘Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral contents. Based on the QAPF classification scheme given by IUGS, we propose a method to determine the mineral contents of volcanic rocks using log data and a genetic algorithm. According to the QAPF scheme, minerals in volcanic rocks are divided into five groups： Q（quartz）, A （Alkaline feldspar）, P （plagioclase）, M （mafic） and F （feldspathoid）. We propose a model called QAPM including porosity for the volumetric analysis of reservoirs. The log response equations for density, apparent neutron porosity, transit time, gamma ray and volume photoelectrical cross section index were first established with the mineral parameters obtained from the Schlumberger handbook of log mineral parameters. Then the volumes of the four minerals in the matrix were calculated using the genetic algorithm （GA）. The calculated porosity, based on the interpretation parameters, can be compared with core porosity, and the rock names given in the paper based on QAPF classification according to the four mineral contents are compatible with those from the chemical analysis of the core samples.
基金National Key Basic Research Project(973)一Formation and Distribution of Oil and Gas of Chinese Typical Coincidence Basins(G19990433).
文摘The discovery of the Tazhong-47 oilfield confirmed that it is realistic to explore oil and gas fields around igneous rocks in the Tarim basin. The favorable conditions for petroleum accumulation due to volcanic activity and igneous rocks formed during the activity show in two aspects. A) The contact surface of igneous rocks and the surrounding sedimentary rocks, like a vertical unconformity surface, formed the conduit of petroleum migration. Petroleum would accumulate once it encountered a trap in which the reservoir had fine porosity and permeability. B) It formed a trap barriered by igneous rocks, or changed or cut the original trap. In addition, volcanic rocks are a kind of potential reservoir, there are many such examples in the world, and oil also shows in the Permian igneous rocks in well Zhong-1 on Tazhong uplift. Petroleum accumulation associated with volcanic activity will be a new exploring field in the Tarim basin.
文摘Unlike previous theories with velocity and/or elastic modulus averaging, we use a three-phase porous rock physics model developed by Santos for analyzing the seismic response of two immiscible fluids in saturated porous media. Considering reservoir reference pressure and coupling drag of two fluids in pores, the effects of frequency, porosity, and gas saturation on the phase velocities of the P-and S-waves are discussed in detail under field conditions. The effects of porosity and gas saturation on Vp/Vs are also provided. The data for our numerical experiments are from a sample of deep volcanic rock from Daqing. The numerical results show that the frequency dispersion effect can be ignored for deep volcanic rocks with low porosity and low permeability. It is concluded that for deep volcanic rocks the effect of gas content in pores on Vp/Vs is negligible but the effect of porosity is significant when there is a certain amount of water contained in the pores. The accurate estimate of lithology and porosity in this case is relatively more important.
文摘The Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management(G-EVER)Consortium among the Asia-Pacific geohazard research institutes was established in 2012 with the main objective of reducing the risk caused by earthquakes,tsunamis and volcanic eruptions worldwide.The first G-EVER workshop was held in Tsukuba,Japan in February 2012.The G-EVER1 accord was approved by the workshop participants which made 10 recommendations that focused on the enhancement of collaboration,sharing of resources and making information about the risks of earthquakes and volcanic eruptions freely available and understandable.
基金sponsored by DST,Govt of India to PCB under USERS scheme(file no.SB/UR/14/2012).
文摘The Barren Island volcano in the Western Sunda Arc has displayed explosive Strombolian eruptions for more than two decades.This recent explosive event,together with the historic and prehistoric volcanic landforms,present reliable information about explosive Strombolian eruptions and the volcanological evolution of the Barren Island volcano.This study is a re-evaluation of existing knowledge and incorporates new information and interpretations of the recent and past volcanic activity on Barren Island.Direct observations of explosive eruptions since 1991 showed discrete events of bursting and ballistic transport of blocks and formation of sustained ash plumes,indicating Strombolian and violent Strombolian eruptions.
