Volcanoes In China Research Articles

Surface deformation caused by the unrest during 2002–2006 of the Changbaishan volcano in China

Surface deformation caused by the unrest during 2002–2006 of the Changbaishan volcano in China

Where do opportunity beliefs come from? Implications of intergenerational social mobility for beliefs about the distribution system in China

People’s understanding of the drivers of inequality is a function of their position in the social structure. Nevertheless, the ways in which intergenerational social mobility is associated with opportunity beliefs remain under researched. Recent findings in cultural sociology suggest that individuals seldom update their beliefs, and that settled dispositions lead people to reproduce their beliefs in their adulthood. This study used a probabilistic and representative survey of Chinese citizens to explore how intergenerational social mobility relates to opportunity beliefs. China presents an interesting context to explore this question, since Chinese society is considered to be highly unequal yet highly tolerant of social inequalities. Our results indicate a U-shaped relationship between social class and opportunity beliefs. The upper class and farmers exhibit stronger meritocratic beliefs than middle-classes. Moreover, upwardly and downwardly mobile individuals show greater weights for origin and destination, respectively. Thus, opportunity beliefs are explained by the social class where they rank lower. These findings suggest that when beliefs are updated through social mobility, they interact with the mobility trajectory. In addition, the stronger meritocratic beliefs of the farmers’ class and the greater weight of social origin for upwardly mobile individuals could help explain the dormant social volcano in China.

Assessment of the potential impact of eruption materials from active volcanoes in China on aviation safety

Assessment of the potential impact of eruption materials from active volcanoes in China on aviation safety

Investigation of hot spring gas components and soil gas fluxes in Arxan Holocene volcanic field, Inner Mongolia, NE China

The latest research results show that there is a unified magma system and heating channel beneath the Arxan volcanic field, indicating a potential risk of eruption. The Arxan volcanic field features multiple gas emission sites (e.g., Jinjianggou hot springs and Yinjianggou hot springs) and exhibits strong hydrothermal activity. In this study, measurements of the hot spring gas composition and soil CO2 flux in the Arxan Holocene volcanic field were conducted, and the results were combined with previous research results to analyze the degassing characteristics of this region. The results show that the volcanic gases in the Arxan volcanic field are composed of 0.07%–1.09% CO2, 0.33–12 ppm CH4, 1.57–53 ppm H2, 800–30,241 ppm He, and 1.14%–1.86% Ar. The He content in this area is notably higher than that in other dormant volcanoes in China. This difference is possibly caused by U–Th decay in the Mesozoic granodiorite and acidic volcanic rocks in the study area, which can produce substantial radiogenic He. The soil gas concentrations near the Jinjianggou and Yinjianggou hot springs are higher than those of two Holocene volcanoes. The peak CO2 concentration in the soil near the Jinjianggou hot spring can reach 35,161 ppm. The single-site soil microseepage CO2 flux in the Arxan volcanic field is 4.66–107.18 g m−2 d−1, and the estimated annual CO2 emission flux from the volcanic field to the atmosphere is 0.63 × 105 t, which also demonstrates that soil CO2 flux of Arxan volcano is comparable to the soil CO2 emission level of the Iwojima volcano.

Soil gas CO2 emissions from active faults: a case study from the Anninghe—Zemuhe fault, Southeastern Tibetan Plateau, China

Introduction: Carbon dioxide emissions from non-volcanic areas are undervalued in the carbon cycle.Methods: First estimates of diffuse CO2 flux from the Anninghe—Zemuhe fault (AZF), Southeastern Tibetan Plateau, China, which suggests this could equal 15% emissions from all volcanoes in China. Following the accumulation chamber method, CO2 flux was investigated at 1,483 points, and along 67 profiles crossing the AZF. Results and discussion: Total CO2 emissions from the AZF were estimated 1.2 Mt yr-1. The relationship between soil gas CO2 fluxes, earthquakes, and fault activity was discussed. The intense fault activity in the southern part of the Zemuhe fault (ZMHF) and the northern part of the Anninghe fault (ANH) was inferred, which could have enhanced the porosity of the soil, and accelerated the water-rock interactions and soil gas emission within the fault zone. The chemical and isotopic data indicated that biogenic CO2 was the primary source of CO2 from the AZF. Produced by interactions between groundwaters and carbonates, soil gas CO2 could migrate to the near surface through cracks. Spatial variations of CO2 flux in soil gas indicate that seismic activity could be responsible for the jumpy variations of CO2 flux. The diffuse CO2 from deep faults may contribute considerably to the greenhouse gas cycles.

A review of present-day deformation of active volcanoes in China between 1970 and 2013

Abstract China has numerous active volcanoes, and more than 10 erupted in the Quaternary. Although a modern eruption event has not occurred in China, the potential risk from volcanic hazards should be noted. With the development of geodetic technologies including the Global Positioning System (GPS), levelling and interferometric synthetic aperture radar (InSAR), volcanologists can now detect the present-day deformation state of China's active volcanoes. In this paper, we summarize the present-day deformation patterns, magma sources and magma plumbing systems of China's active volcanoes between 1970 and 2013. The results show that the most active volcano in China is the Changbaishan volcano; it showed significant inflation from 2002–03, with the deformation becoming gradually weaker after 2003, indicating that it had been experiencing a magma process during 2000–10. A point source at a depth of c. 10 km was responsible for the observed deformation. The Leiqiong volcanic field showed a trough pattern deformation during 2007–10, which was interpreted as a dyke intrusion model. Fluctuant deformation patterns were shown in the Tengchong volcanic field. The Longgang volcanic field had experienced a volcano-wide uplift during the 1970s and 1990s. Deformation was observed in the Tatun volcanic field from 2006–13, and two shallow sources account for the observed deformation. These volcanoes merit further monitoring given possible evidence of deformation. No obvious deformation related to volcanic activity was observed at the Ashikule volcanic field from 2003–11. The results provide a basic introduction to the deformation state of China's active volcanoes, and may be helpful for evaluating the activity levels of China's volcanoes and mitigating the risks of future volcanic hazards.

Knowledge base of Cenozoic volcanoes in China

Abstract Knowledge management plays an important role in scientific research and provides a basis for technical development in the era of Big Data. Studies of Cenozoic volcanoes in China have been undertaken for more than half a century, generating plentiful relevant literature and data. However, these data have stayed scattered between different authors and libraries, and this hampers management and access. Based on theories, knowledge bases and related technologies, we developed the Knowledge Base of Cenozoic Volcanoes (KBCV) to collect such volcanic data in China. The directory tree of the KBCV is structured based on five levels according to the volcano distribution, magma origin, data type and file format. The KBCV supports querying, searching and browsing. It can provide well-managed Cenozoic volcanic data and technical support for scientific research and public communication. The KBCV is still in its early stages and is imperfect with respect to data completeness and universalization of the system, and efforts are being made to continuously develop and popularize the system.

Current situation of early warning and emergency countermeasures of volcanic eruptions in China

Abstract Volcanic eruptions, as major natural disasters, often cause considerable numbers of casualties and economic losses. Given the substantial potential hazards posed to society, volcanic eruptions have become a central concern for national public safety systems. This paper introduces the risk degrees and classification of activity of major active volcanoes in China, reviews early warning policies in the government response to volcanic eruptions, compares the early warning levels of China and the USA, and proposes an early warning theme adapted to the characteristics of volcanic activity in mainland China. The current volcanic warning system of China still has considerable room for improvement; therefore, improvements in monitoring volcanic activities and the antihazard capacity of volcanic eruption in the future are urgently needed.

The impact of volcanic ash on the safety of aviation industry: review of China's current situation

Abstract By synthesizing relevant research findings from China and other countries, this paper discusses the distribution and eruption types of volcanoes in China. An analysis of the spreading characteristics of volcanic ash possibly caused by volcanic eruptions such as those from Changbaishan is presented, and the impact of volcanic ash on aviation flight safety, as well as several key methods of monitoring volcanic ash, are discussed. This paper also outlines the operational process of China's aviation industry in addressing volcanic ash and compares and analyses the handling of volcanic ash by civil aviation industries globally. Further, ways of dealing with volcanic ash are then suggested for China's aviation industry.

Age of a late Quaternary (13.6 cal kyr BP) eruption and associated marker tephra of the Tengchong volcanoes, Yunnan Province, southwestern China

The Tengchong volcanoes in western Yunnan Province are some of the youngest volcanoes in China, and determining their eruption ages would further our understanding of their genesis and historical activity. In this study, the age of a late Quaternary eruption of Dayingshan volcano was obtained by dating organic-rich sediments that envelope a 5-cm-thick visible tephra layer found in the Yubi peat section. Compositionally, the purified glass shards extracted from the layer by density separation are calc-alkaline trachyandesite and trachyte/trachydacite, which is consistent with the composition of the Dayingshan lava. An age-depth model of the Yubi section was constructed from accelerator mass spectrometry (AMS) 14C dating of peat samples and Poisson models of deposition (P_sequence) functions, using OxCal with the IntCal 13 database. This yielded an age for the tephra layer of 13,642 ± 84 cal yr BP. A nearly identical tephra layer occurs in the Qinghai Crater Lake sediments. The Yubi tephra is now a reliable age and stratigraphic marker layer, useful for regional paleoclimate and tephrochronology research.

Waveform inversion of SS precursors: An investigation of the northwestern Pacific subduction zones and intraplate volcanoes in China

The arrival time and amplitude of underside reflections from mantle seismic discontinuities (SS precursors) have made major contributions to the understanding of mantle composition and dynamics. In this study, we introduce a nonlinear waveform inversion technique to simultaneously constrain shear velocities and discontinuity depths beneath the northwestern Pacific subduction system. Based exclusively on a large SS precursor waveform dataset, we are able to clearly delineate the morphology of the descending Pacific plate, which flattens at the base of the upper mantle and extends westward by ~1500km toward northern-central China. Our grid search yields the maximum correlation between shear velocity and transition zone thickness at an angle of ~30°, consistent with the reported average slab dip beneath the study region. The strongly positive correlation suggests predominantly thermal, rather than compositional, variations along the descending Pacific plate. The joint depth-velocity solution also shows a 5–10km depression of the 410km discontinuity and an average decrease of 1.2% in upper mantle shear velocity beneath the intraplate volcanic fields in northeastern China. This anomaly, which reaches the middle of the upper mantle transition zone beneath the Changbai hotspot, initiates at a significantly shallower (~320km) depth beneath the Wudalianchi region. High amplitude reflections at depths greater than 410km suggest a water-poor melt layer in possible association with 1) decompression melting from passive upwelling and/or 2) active upwelling through a slab window.

Geological background and geodynamic mechanism of Mt. Changbai volcanoes on the China–Korea border

The intense Cenozoic volcanism of Mt. Changbai provides a natural laboratory for investigating the characteristics of volcanism and the dynamical evolution of the Northeast Asian continental margin. Mt. Changbai volcanoes predominantly consist of Wangtian'e volcano in China, Tianchi volcano spanning China and DPR Korea, and Namphothe volcano in DPR Korea. Geochronology data and historical records of volcanism indicate that the three eruption centers were formed in the following sequence: Wangtian'e volcano to Namphothe and Tianchi volcano, advancing temporally and spatially from southwest to northeast. The three eruption centers of Mt. Changbai volcano are located close together, have similar magma evolution trends, bimodal volcanic rock distribution, and an enriched mantle source, etc. Although the Cenozoic volcanism in Mt. Changbai is thought to be somewhat related to the subduction of the Western Pacific Plate, the regularity of volcanic activity and petrography characteristics have continental rift affinity. We therefore conclude that the occurrence of synchronous and similar volcanic activity on both sides of the Japan Sea (i.e., the Japan Arc and Northeast China) likely respond to the rift expansion and the back-arc spreading of Japan Sea. From many perspectives, Mt. Changbai volcano is a giant active volcano with hidden potentially eruptive risks.

Estimation of greenhouse gas flux from mud volcanoes in the Dushanzi area, southern Junggar Basin of Northwest China

Mud volcanoes are a direct manifestation of deep tectonic and subsurface fluid invasion activities near the earth surface. Such activity emits large amounts of greenhouse gases, predominantly methane, and is also responsible for an important part of the total geologic carbon flux to the atmosphere. However, there is little research on estimation of greenhouse gas flux from mud volcanoes in China. The mud volcanoes in the Dushanzi area of the Xinjiang Uygur Autonomous Region are typical and very active, emitting various types of greenhouse gases. We used a sealed chamber connected to a methane detector to measure the <italic>in situ</italic> gas emission rate and estimate flux. Based on well-known research methods, experience with greenhouse gas emissions from mud volcanoes abroad, and gas composition data, we estimated total flux of those gases emitted from the Dushanzi mud volcanoes. Greenhouse gas fluxes from macro-seeps in areas DSZ-01 and DSZ-03 exceeded 161 t/a. Flux by micro-seepage in areas DSZ-01 (314 m²), DSZ-02 (8400 m²), and DSZ-03 (314 m²) was 16.6 t/a.

Climatic impact of the Millennium eruption of Changbaishan volcano in China: New insights from high‐precision radiocarbon wiggle‐match dating

AbstractChangbaishan volcano in northeast China, previously dated to have erupted around the mid‐10th century A.D., is renowned for producing one of the largest eruptions in history (magnitude 6.8) and thus speculated to have substantial climatic impact. Here we report a new high‐precision 14C wiggle‐match age of A.D. 946 ± 3 obtained from a 264 year old tree trunk (with bark) killed during the eruption, using the OxCal's Bayesian modeling approach with 27 sequentially sampled annual rings of decadal intervals. The new chronology conforms well to the calendar date of A.D. 946 for the eruption inferred from historical documentary evidence. We find no stratospherically loaded sulfate spike that might be associated with the A.D. 946 eruption in the global volcanism record from the GISP2 ice core, suggesting the stratospheric sulfate aerosols produced during the eruption were not transported to the arctic region, due probably to its relatively low stratospheric sulfur emission and the seasonal effects of the atmospheric circulation at the time of the eruption that likely occurred in the winter of A.D. 946–947. Since the stratospheric volcanic sulfates are the main cause of large‐scale climate perturbations, this finding indicates that the Millennium eruption of Changbaishan volcano might have limited regional climatic effects, rather than global or hemispheric impact as implied by its magnitude.

Prokaryotic diversity of an active mud volcano in the Usu City of Xinjiang, China

The Usu mud volcanoes are the largest group of terrestrial mud volcanoes in China. The volcanoes are located in a typical arid and semi-arid region, and the group consists of 36 erupting active mud volcanoes. In this study, the prokaryotic diversity and community structure in the sediment of an active mud volcano were investigated by constructing bacterial and archaeal clone libraries of the 16S rRNA gene. A total of 100 bacterial and 100 archaeal clones were analysed and found to comprise 11 and 7 distinct phylotypes, respectively. The bacterial phylotypes were classified into three phyla (Proteobacteria, Actinobacteria, and Fusobacteria). Of these, Proteobacteria were the most abundant bacterial group, with Deltaproteobacteria dominating the sediment community, and these were affiliated with the order Desulfuromonadales. The archaeal phylotypes were all closely related to uncultivated species, and the majority of the members were related to the orders Methanosarcinales and Halobacteriales of the Euryarchaeota originating from methane hydrate bearing or alkaline sediments. The rest of the archaeal phylotypes belonged to the phylum Crenarchaeota, with representatives from similar habitats. These results suggested that a large number of novel microbial groups and potential methanogenesis may exist in this unique ecosystem.

Deep structure and origin of active volcanoes in China

We synthesize significant recent results on the deep structure and origin of the active volcanoes in mainland China. Magmatism in the western Pacific arc and back-arc areas is caused by dehydration of the subducting slab and by corner flow in the mantle wedge, whereas the intraplate magmatism in China has different origins. The active volcanoes in Northeast China (such as the Changbai and Wudalianchi) are caused by hot upwelling in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well. The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate (or Indian plate). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs’ deep subduction in the east and the Indian slab’s deep subduction in the west down to the lower mantle. The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab–plume interactions.

Paleomagnetism of the Datong monogenetic volcanoes in China: paleodirection and paleointensity during the middle to early Brunhes Chron

Abstract Paleomagnetic measurements were conducted on Datong volcanic rocks from China, which are thought to have formed in the mid to early Brunhes Chron. Meaningful site-mean paleodirections were obtained from 21 sites which are considered to represent 17 independent cooling units. They give a mean VGP (virtual geomagnetic pole) position of (76.5°N, 7.9°E) with A95=7.7° (N=17), which is statistically distinct from geographic north. This dataset also yields an ASD (angular standard deviation) of 17.2° around the mean VGP position. Because the paleodirections form two clusters, the samples may record the paleomagnetic field during two different short periods and therefore may not average out paleosecular variation. Paleointensity measurements were conducted using three different methods. The DHT and LTD-DHT Shaw methods, the Thellier method, and the microwave Thellier method were applied to 119, 29 and 73 specimens respectively, and they give 66, 16 and 12 successful results (success rates are 55, 55 and 16%). From the LTD-DHT Shaw dataset, eight acceptable site-mean paleointensities are obtained. They give an average VDM (virtual dipole moment) of 3.79±1.94x 1022 A m2. This is 56% lower than the average VDM of 5.91±1.74x 1022 A m2 (N=14) calculated from the selected Thellier data from the latest paleointensity database using the same criteria. One possible reason for this difference might be systematic overestimations of paleointensities by the Thellier method on volcanic rocks.

Three active volcanoes in China and their hazards

The active volcanoes in China are located in the Changbaishan area, Jingbo Lake, Wudalianchi, Tengchong and Yutian. Several of these volcanoes have historical records of eruption and geochronological evidence of Holocene activity. Tianchi Volcano is a well-preserved Cenozoic polygenetic central volcano, and, due to its recent history of powerful explosive eruptions of felsic magmas, with over 100,000 people living on its flanks is a high-risk volcano. Explosive eruptions at 4000 and 1000 years bp involved plinian and ignimbrite phases. The Millennium eruption (1000 years bp) involved at least 20–30 km 3 of magma and was large enough to have a global impact. There are 14 Cenozoic monogenetic scoria cones and associated lavas with high-K basalt composition in the Wudalianchi volcanic field. The Laoheishan and Huoshaoshan cones and related lavas were formed in 1720–1721 and 1776 ad. There are three Holocene volcanoes, Dayingshan, Maanshan, and Heikongshan, among the 68 Quaternary volcanoes in the Tengchong volcanic province. Three of these volcanoes are identified as active, based on geothermal activity, geophysical evidence for magma, and dating of young volcanic rocks. Future eruptions of these Chinese volcanoes pose a significant threat to hundreds of thousands of people and are likely to cause substantial economic losses.