Volcanoes

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Benjamin Van Wyk De Vries - One of the best experts on this subject based on the ideXlab platform.

  • Water in Volcanoes: evolution, storage and rapid release during landslides.
    Bulletin of Volcanology, 2016
    Co-Authors: Audray Delcamp, Gioachino Roberti, Benjamin Van Wyk De Vries
    Abstract:

    Volcanoes can store and drain water that is used as a valuable resource by populations living on their slopes. The water drainage and storage pattern depend on the volcano lithologies and structure, as well as the geological and hydrometric settings. The drainage and storage pattern will change according to the hydrometric conditions, the vegetation cover, the eruptive activity and the long- and short-term volcano deformation. Inspired by our field observations and based on geology and structure of volcanic edifices, on hydrogeological studies, and modelling of water flow in opening fractures, we develop a model of water storage and drainage linked with volcano evolution. This paper offers a first-order general model of water evolution in Volcanoes. The volcano’s water plays an important role in volcano stability and instability. Nevertheless, the migration and storage of volcanic water prior and during landslide have not been extensively studied in regard to volcano evolution. We further explore this role and its impact on debris avalanche emplacement behaviour. Isolated water-saturated domains will favour ductile deformation, and unequal distribution of water within the debris avalanche partly explains the coeval occurrence of brittle and ductile deformation, indicating complex rheologies, and varied emplacement mechanisms. If the volcano prior to landslide is storing large amounts of water, this water will quickly flow in the landslide and will form a basal slurry upon which the avalanche will spread further.

  • A sagging-spreading continuum of large volcano structure
    Geology, 2013
    Co-Authors: P.k. Byrne, Benjamin Van Wyk De Vries, E.p. Holohan, M. Kervyn, Valentin R. Troll, J.b. Murray
    Abstract:

    Gravitational deformation strongly infl uences the structure and eruptive behavior of large Volcanoes. Using scaled analog models, we characterize a range of structural architectures produced by volcano sagging and volcano spreading. These arise from the interplay of variable basement rigidity and volcano-basement (de-)coupling. From comparison to Volcanoes on Earth (La Réunion and Hawaii) and Mars (Elysium and Olympus Montes), the models highlight a structural continuum in which large Volcanoes throughout the Solar System lie.

Songchuen Chen - One of the best experts on this subject based on the ideXlab platform.

  • distribution and characters of the mud diapirs and mud Volcanoes off southwest taiwan
    Journal of Asian Earth Sciences, 2014
    Co-Authors: Songchuen Chen, Shukun Hsu, Yunshuen Wang, Sanhsiung Chung, Pochun Chen, Chinghui Tsai, Charshine Liu, Hsiaoshan Lin, Yuanwei Lee
    Abstract:

    Abstract In order to identify the mud diapirs and mud Volcanoes off SW Taiwan, we have examined ∼1500 km long MCS profiles and related marine geophysical data. Our results show ten quasi-linear mud diapirs, oriented NNE–SSW to N–S directions. Thirteen mud Volcanoes are identified from the multibeam bathymetric data. These mud Volcanoes generally occur on tops of the diapiric structures. Moreover, the active mud flow tracks out of mud Volcanoes MV1, MV3 and MV6 are observed through the high backscatter intensity stripes on the sidescan sonar images. The heights of the cone-shaped mud Volcanoes range from 65 m to 345 m, and the diameters at base from 680 m to 4100 m. These mud Volcanoes have abrupt slopes between 5.3° and 13.6°, implying the mudflow is active and highly viscous. In contrast, the flat crests of mud Volcanoes are due to relative lower-viscosity flows. The larger cone-shaped mud Volcanoes located at deeper water depths could be related to a longer eruption history. The formation of mud diapirs and Volcanoes in the study area are ascribed to the overpressure in sedimentary layers, compressional tectonic forces and gas-bearing fluids. Especially, the gas-bearing fluid plays an important role in enhancing the intrusion after the diapirism as a large amount of gas expulsions is observed. The morphology of the upper Kaoping Slope is mainly controlled by mud diapiric intrusions.

Alexei V Milkov - One of the best experts on this subject based on the ideXlab platform.

  • global distribution of mud Volcanoes and their significance in petroleum exploration as a source of methane in the atmosphere and hydrosphere and as a geohazard
    2005
    Co-Authors: Alexei V Milkov
    Abstract:

    Mud Volcanoes occur worldwide in areas of rapid sedimentation, lateral tectonic compression, and geologically recent magmatic activity. The total number of individual mud Volcanoes on the Earth exceeds 2,000 and this number is growing as the exploration of deep oceans continues. Sediments and fluids expelled from mud Volcanoes provide useful information on the geology and petroleum potential of deep sedimentary basins. Mud Volcanoes are considered to be a minor but yet not fully recognized and properly quantified source of greenhouse gases (mainly methane) in the atmosphere. A significant (but still uncertain) amount of methane may escape into the ocean and affect the size and characteristics of the ocean carbon pool. Finally, mud Volcanoes represent a recognized geohazard that affects life forms and petroleum exploitation. This paper reviews the results of recent studies into worldwide mud volcanism.

  • worldwide distribution of submarine mud Volcanoes and associated gas hydrates
    Marine Geology, 2000
    Co-Authors: Alexei V Milkov
    Abstract:

    Abstract The list of known and inferred submarine mud Volcanoes is presented in this paper. They occur worldwide on shelves, continental and insular slopes and in the abyssal parts of inland seas. Submarine mud Volcanoes are distributed on the Earth more extensively than their subaerial analogs. The estimated total number of known and inferred deep-water mud Volcanoes is 103–105. There are two key reasons for the formation of submarine mud Volcanoes—high sedimentation rate and lateral tectonic compression. Submarine mud Volcanoes form by two basic mechanisms: (1) formation on the top of a seafloor-piercing shale diapir; (2) formation due to the rise of fluidized sediments along faults. Fluid migration is critical to the formation of a mud volcano. Gas hydrates are often associated with deep-water mud Volcanoes and have many common features from one accumulation to another. Gas hydrates form by conventional low-temperature hydrothermal process around the central part of a mud volcano and by metasomatic processes at its periphery. A preliminary global estimate of methane accumulated in gas hydrates associated with mud Volcanoes is about 1010–1012 m3 at standard temperature and pressure.

Yuanwei Lee - One of the best experts on this subject based on the ideXlab platform.

  • distribution and characters of the mud diapirs and mud Volcanoes off southwest taiwan
    Journal of Asian Earth Sciences, 2014
    Co-Authors: Songchuen Chen, Shukun Hsu, Yunshuen Wang, Sanhsiung Chung, Pochun Chen, Chinghui Tsai, Charshine Liu, Hsiaoshan Lin, Yuanwei Lee
    Abstract:

    Abstract In order to identify the mud diapirs and mud Volcanoes off SW Taiwan, we have examined ∼1500 km long MCS profiles and related marine geophysical data. Our results show ten quasi-linear mud diapirs, oriented NNE–SSW to N–S directions. Thirteen mud Volcanoes are identified from the multibeam bathymetric data. These mud Volcanoes generally occur on tops of the diapiric structures. Moreover, the active mud flow tracks out of mud Volcanoes MV1, MV3 and MV6 are observed through the high backscatter intensity stripes on the sidescan sonar images. The heights of the cone-shaped mud Volcanoes range from 65 m to 345 m, and the diameters at base from 680 m to 4100 m. These mud Volcanoes have abrupt slopes between 5.3° and 13.6°, implying the mudflow is active and highly viscous. In contrast, the flat crests of mud Volcanoes are due to relative lower-viscosity flows. The larger cone-shaped mud Volcanoes located at deeper water depths could be related to a longer eruption history. The formation of mud diapirs and Volcanoes in the study area are ascribed to the overpressure in sedimentary layers, compressional tectonic forces and gas-bearing fluids. Especially, the gas-bearing fluid plays an important role in enhancing the intrusion after the diapirism as a large amount of gas expulsions is observed. The morphology of the upper Kaoping Slope is mainly controlled by mud diapiric intrusions.

François Henri Cornet - One of the best experts on this subject based on the ideXlab platform.

  • effects of topography on the interpretation of the deformation field of prominent Volcanoes application to etna
    Geophysical Research Letters, 1998
    Co-Authors: Valerie Cayol, François Henri Cornet
    Abstract:

    We have investigated the effects of topography on the surface-deformation field of Volcanoes. Our study provides limits to the use of classical half-space models. Considering axisymmetrical Volcanoes, we show that interpreting ground-surface displacements with half-space models can lead to erroneous estimations of the shape of the deformation source. When the average slope of the flanks of a volcano exceeds 20°, tilting in the summit area is reversed to that expected for a flat surface. Thus, neglecting topography may lead to misinterpreting an inflation of the source as a deflation. Comparisons of Mogi's model with a three-dimensional model shows that ignoring topography may lead to an overestimate of the source-volume change by as much as 50% for a slope of 30°. This comparison also shows that the depths calculated by using Mogi's solution for prominent Volcanoes should be considered as depths from the summit of the edifices. Finally, we illustrate these topographic effects by analyzing the deformation field measured by radar interferometry at Mount Etna during its 1991–1993 eruption. A three-dimensional modeling calculation shows that the flattening of the deflation field near the volcano's summit is probably a topographic effect.

  • Effects of topography on the interpretation of the deformation field of prominent Volcanoes—Application to Etna
    Geophysical Research Letters, 1998
    Co-Authors: Valerie Cayol, François Henri Cornet
    Abstract:

    We have investigated the effects of topography on the surface-deformation field of Volcanoes. Our study provides limits to the use of classical half-space models. Considering axisymmetrical Volcanoes, we show that interpreting ground-surface displacements with half-space models can lead to erroneous estimations of the shape of the deformation source. When the average slope of the flanks of a volcano exceeds 20°, tilting in the summit area is reversed to that expected for a flat surface. Thus, neglecting topography may lead to misinterpreting an inflation of the source as a deflation. Comparisons of Mogi's model with a three-dimensional model shows that ignoring topography may lead to an overestimate of the source-volume change by as much as 50% for a slope of 30°. This comparison also shows that the depths calculated by using Mogi's solution for prominent Volcanoes should be considered as depths from the summit of the edifices. Finally, we illustrate these topographic effects by analyzing the deformation field measured by radar interferometry at Mount Etna during its 1991–1993 eruption. A three-dimensional modeling calculation shows that the flattening of the deflation field near the volcano's summit is probably a topographic effect.