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Sample records for volcano taupo volcanic

  1. The petrology, geochronology and geochemistry of Hauhungatahi volcano, S.W. Taupo Volcanic Zone

    Science.gov (United States)

    Cameron, Errol; Gamble, John; Price, Richard; Smith, Ian; McIntosh, William; Gardner, Mairi

    2010-02-01

    Hauhungatahi volcano is an eroded andesitic edifice 10 km west of Ruapehu volcano constructed on an upfaulted block of Mesozoic marine sediments. Hauhungatahi andesites are distinctively clinopyroxene-phyric with high ratios of clinopyroxene:plagioclase. This contrasts with the plagioclase-phyric dominated assemblages in the stratovolcanoes such as Ruapehu and Tongariro. Hauhungatahi andesites show high MgO (> 8.0% wt), Sr (> 400 ppm), Ni (> 100 ppm) and Cr (> 400 ppm) and low Si, Rb, Ba and Zr relative to andesites from Ruapehu volcano, with fractionated LREE (Ce/Sm) n ~ 2 and flat HREE (Dy/Yb) n ~ 1. Sr-isotope ratios are lower at equivalent Nd isotope ratios than Ruapehu andesites of the (oldest) Te Herenga Formation. 40Ar/ 39Ar step-heating experiments of groundmass concentrates of 4 samples have yielded ages between 881 ± 83 ka and 961 ± 59 ka, with a weighted mean age of 933 ± 46 ka, indicating that Hauhungatahi is significantly older than Ruapehu Volcano where volcanism commenced ~ 250-300 ka. Hauhungatahi is therefore similar in age to the older andesitic edifices that are marginal to the TVZ (eg Titiraupenga, Pureora and Rolles Peak). We suggest that these high-Mg andesites hold clues to the early conditioning of the lithosphere beneath TVZ, prior to the establishment of the large andesite stratovolcanoes that presently dominate the skyline at the southern end of TVZ. The relatively low abundance of plagioclase in the phenocryst assemblages hints at high P H 2O and possible involvement of amphibole in the source.

  2. A catalogue of caldera unrest at Taupo Volcanic Centre, New Zealand, using the Volcanic Unrest Index (VUI)

    Science.gov (United States)

    Potter, Sally H.; Scott, Bradley J.; Jolly, Gill E.; Johnston, David M.; Neall, Vince E.

    2015-09-01

    Caldera unrest occurs frequently at Taupo Volcanic Centre (TVC), New Zealand, occasionally resulting in deleterious socio-economic impacts. This large silicic volcano most recently erupted in 232 AD in an explosive, caldera-forming rhyolitic eruption, devastating the central North Island. Eruptions are preceded by volcanic unrest, often consisting of seismicity, deformation, degassing, and/or geothermal system changes. These phenomena may also occur due to non-magmatic processes, complicating eruption forecasting. As volcanic unrest may or may not lead to an eruption, it needs to be characterised to provide effective warnings; this is best achieved by understanding past unrest. In this research, a catalogue of caldera unrest at TVC is developed using an historical chronology methodology, spanning from 1872 to December 2011. The Volcanic Unrest Index (VUI), which is introduced by Potter et al. (2015), is estimated for the catalogue, demonstrating its use and providing a characterisation of unrest at TVC. Sixteen episodes of unrest are identified; 4 are classified as moderate unrest (VUI 3), and 12 are classified as minor unrest (VUI 2). There has been median interval of approximately 3 years between unrest episodes and a median unrest episode duration of just under 5 months. This research provides context for future caldera unrest crises at TVC and contributes to the global caldera unrest dataset.

  3. Energy transport processes in a brittle ductile intrusive model of the Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Weir, Graham J.

    1998-08-01

    The implications of the findings of recent GPS and micro-seismic studies in the Taupo Volcanic Zone (TVZ), New Zealand, on models of processes transporting mass, heat and chemicals are discussed. It is argued that in addition to the well established process of groundwater convection extracting heat and chemicals by interacting with magmatic intrusives under the TVZ, that two other processes may be important. Firstly, the existence of a ductile layer with very low permeability between about 8 to 15 km depth will produce a region of `enhanced conduction' in which very high conductive fluxes of energy arise from a temperature distribution which varies exponentially with depth. Secondly, water may transport up through the ductile layer, as a result of extensional processes in the ductile region. If extension is occurring at about 8 mm/yr, then geothermal heat transfer in the TVZ of about 4200 MW is made up from about 1200 MW from the cooling of intrusives in the brittle region in the upper 8 km; of about an additional 1900 MW of conducted heat entering the brittle region from the ductile region; and about an additional 1100 MW from water transport through the ductile region. Provided this water flow has a chloride concentration similar to that emitted from nearby volcanoes, then the total chloride transport from the TVZ is about 3.5 kg/s, as suggested by average enthalpy to chloride ratios in the TVZ of about 1.2 MJ/g. The present high heat and mass transport processes in the TVZ are assumed to result from the passive filling of volume created from extensional processes under the TVZ, plus conductive and/or convective heating processes below 15 km depth.

  4. Distinguishing styles of explosive eruptions at Erebus, Redoubt and Taupo volcanoes using multivariate analysis of ash morphometrics

    Science.gov (United States)

    Avery, Meredith R.; Panter, Kurt S.; Gorsevski, Pece V.

    2017-02-01

    The style and dynamics of volcanic eruptions control the level and type of hazards posed for local populations and can have a temporary long-range impact on climate if eruptions are extremely energetic. The purpose of this study is to provide a statistical approach to ash morphometrics in order to provide a means by which to evaluate diverse eruption styles and mechanisms of fragmentation. The methodology presented can be applied to tephra deposits worldwide and may aid volcanic hazard mitigation by better defining a volcano's history of explosive behavior. Ash-sized grains were collected from tephra deposits on Mount Erebus, Antarctica (imaged by scanning electron microscopy. Morphometric properties were determined using image processing software and then evaluated by several statistical methods. Discriminant analysis of all parameters was found to be the best at differentiating the tephra deposits and allowing for interpretation of eruptive styles in conjunction with field observations. A linear array of data forming a positive slope in factor space, which explains > 99% of the total data variance, is interpreted to represent a continuum between fragmentations involving water-magma interaction ("wet") to grains that were formed predominately by magmatic ("dry") fragmentation mechanisms. The Taupo Hatepe ash, which was deposited from a phreatoplinian eruption column, has the highest factor values in the array, which signifies, in part, more rectangular/blocky morphologies with smooth grain edges. Factor values for the 2009 Redoubt eruption (events 2-4) are nearly as high as Hatepe ash and based on this we suggest that it was produced, in part, by phreatomagmatic fragmentation. This is supported by field observations that document melting and eruption through glacial ice during the early phases of the 2009 activity. Redoubt ash grains from later stages of the same eruption (events 9-18) show a significant shift to lower values in factor space (more irregular

  5. A multidisciplinary approach to quantify the permeability of the Whakaari/White Island volcanic hydrothermal system (Taupo Volcanic Zone, New Zealand)

    Science.gov (United States)

    Heap, Michael J.; Kennedy, Ben M.; Farquharson, Jamie I.; Ashworth, James; Mayer, Klaus; Letham-Brake, Mark; Reuschlé, Thierry; Gilg, H. Albert; Scheu, Bettina; Lavallée, Yan; Siratovich, Paul; Cole, Jim; Jolly, Arthur D.; Baud, Patrick; Dingwell, Donald B.

    2017-02-01

    Our multidisciplinary study aims to better understand the permeability of active volcanic hydrothermal systems, a vital prerequisite for modelling and understanding their behaviour and evolution. Whakaari/White Island volcano (an active stratovolcano at the north-eastern end of the Taupo Volcanic Zone of New Zealand) hosts a highly reactive hydrothermal system and represents an ideal natural laboratory to undertake such a study. We first gained an appreciation of the different lithologies at Whakaari and (where possible) their lateral and vertical extent through reconnaissance by land, sea, and air. The main crater, filled with tephra deposits, is shielded by a volcanic amphitheatre comprising interbedded lavas, lava breccias, and tuffs. We deployed field techniques to measure the permeability and density/porosity of (1) > 100 hand-sized sample blocks and (2) layered unlithified deposits in eight purpose-dug trenches. Our field measurements were then groundtruthed using traditional laboratory techniques on almost 150 samples. Our measurements highlight that the porosity of the materials at Whakaari varies from ∼ 0.01 to ∼ 0.7 and permeability varies by eight orders of magnitude (from ∼ 10-19 to ∼ 10-11 m2). The wide range in physical and hydraulic properties is the result of the numerous lithologies and their varied microstructures and alteration intensities, as exposed by a combination of macroscopic and microscopic (scanning electron microscopy) observations, quantitative mineralogical studies (X-ray powder diffraction), and mercury porosimetry. An understanding of the spatial distribution of lithology and alteration style/intensity is therefore important to decipher fluid flow within the Whakaari volcanic hydrothermal system. We align our field observations and porosity/permeability measurements to construct a schematic cross section of Whakaari that highlights the salient findings of our study. Taken together, the alteration typical of a volcanic

  6. Ecological characteristics and management of geothermal systems of the Taupo Volcanic Zone, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Boothroyd, Ian K.G. [Golder Associates Ltd., P.O. Box 33849, Takapuna, and School of Geography, Geology and Environmental Science, University of Auckland, Private Bag 92019, Auckland (New Zealand)

    2009-03-15

    New Zealand has an array of geothermal systems with distinctive ecological features, with many occurring in the Taupo Volcanic Zone in the Central North Island. Associated with these geothermal features are characteristic geophysical and geochemical components, and distinctive terrestrial and aquatic ecosystems with many attributes that are common across a range of the biotic groups. Zonation amongst vegetation communities is closely related to soil temperature and these associations generally occur in a predictable sequence along the soil temperature gradient. Similarly, clear distinctions in aquatic flora and fauna occur longitudinally downstream from the source of thermal springs and vertically on geyser mounds. The characteristic vegetation communities associated with geothermal fields and the invertebrate and algal communities found in geothermally influenced springs and streams are described, in particular the features of the Wairakei geothermal field. At this field four plant associations are recognized (non-vegetated soilfield, prostrate kanuka shrubland, prostrate kanuka scrub, mixed fernland), but all the major aquatic macroinvertebrate groups are represented and commonly found in natural freshwaters throughout New Zealand. The current management of geothermal ecosystems is reviewed with particular reference to the Waikato region of New Zealand. Management of geothermal resources in New Zealand aims to balance development with the protection of highly valued surface features via a series of regional policies, rules and regulations. Geothermal habitats, ecological gradients, and at-risk geothermal plants are included in the definition of geothermal systems for management purposes. With the recognition of the unique ecological diversity and function of geothermal ecosystems, knowledge and understanding of their ecological characteristics will be critical to the ability to utilize and sustain geothermal resources into the future. (author)

  7. Off-axis magmatism along a subaerial back-arc rift: Observations from the Taupo Volcanic Zone, New Zealand.

    Science.gov (United States)

    Hamling, Ian J; Hreinsdóttir, Sigrun; Bannister, Stephen; Palmer, Neville

    2016-06-01

    Continental rifting and seafloor spreading play a fundamental role in the generation of new crust. However, the distribution of magma and its relationship with tectonics and volcanism remain poorly understood, particularly in back-arc settings. We show evidence for a large, long-lived, off-axis magmatic intrusion located on the margin of the Taupo Volcanic Zone, New Zealand. Geodetic data acquired since the 1950s show evidence for uplift outside of the region of active extension, consistent with the inflation of a magmatic body at a depth of ~9.5 km. Satellite radar interferometry and Global Positioning System data suggest that there was an increase in the inflation rate from 2003 to 2011, which correlates with intense earthquake activity in the region. Our results suggest that the continued growth of a large magmatic body may represent the birth of a new magma chamber on the margins of a back-arc rift system.

  8. Giant rafted pumice blocks from the most recent eruption of Taupo volcano, New Zealand: Insights from palaeomagnetic and textural data

    Science.gov (United States)

    von Lichtan, I. J.; White, J. D. L.; Manville, V.; Ohneiser, C.

    2016-05-01

    Giant blocks of pumice lie strewn along a former shoreline of intracaldera Lake Taupo, New Zealand, and are the sole subaerial evidence of the most recent volcanism at the Taupo supervolcano. Geochemically they are identical to material erupted during the complex and multiphase 1.8 ka Taupo eruption, which they post-date by one to two decades. The blocks, some of which are > 10 m long, show complex jointing patterns indicative of both surface chilling and continued interior expansion, as well as heterogeneous vesicularity, with dense rims (mean density 917 kg/m3) grading via an intervening transition zone (mean density 844 kg/m3) into a more highly vesicular interior (mean density 815 kg/m3). Analysis of thermal demagnetisation data indicates significant reorientation of the blocks as they cooled through a series of blocking temperatures. Some parts of block rims cooled to below 580 °C well before emplacement on the shore, whereas other parts in the interior and transition zones, which cooled more slowly, acquired different orientations before stranding. Some block interiors cooled after blocks were finally deposited, and record the direction of the 1.8 ka field. The blocks are believed to be derived from one or both of a pair of rhyolitic lava domes that developed on the bed of Lake Taupo several decades after the climactic Taupo eruption over the inferred vent area. These, and similar giant rafted pumice blocks in other marine and lacustrine settings raise a number of questions about how volatile-rich felsic magma can be erupted underwater with only limited thermal fragmentation. Furthermore, the prolonged flotation of out-sized fragments of vesiculated magma formed during subaqueous dome-growth contrasts with the rapid sinking of smaller pieces of hot plinian pumice under laboratory conditions. The genesis of pumice forming the blocks is not entirely clear. Most simply the blocks may represent part of a vesiculated carapace of a growing lava dome, broken loose

  9. Volcanic hazards at Atitlan volcano, Guatemala

    Science.gov (United States)

    Haapala, J.M.; Escobar Wolf, R.; Vallance, James W.; Rose, William I.; Griswold, J.P.; Schilling, S.P.; Ewert, J.W.; Mota, M.

    2006-01-01

    Atitlan Volcano is in the Guatemalan Highlands, along a west-northwest trending chain of volcanoes parallel to the mid-American trench. The volcano perches on the southern rim of the Atitlan caldera, which contains Lake Atitlan. Since the major caldera-forming eruption 85 thousand years ago (ka), three stratovolcanoes--San Pedro, Toliman, and Atitlan--have formed in and around the caldera. Atitlan is the youngest and most active of the three volcanoes. Atitlan Volcano is a composite volcano, with a steep-sided, symmetrical cone comprising alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs. Eruptions of Atitlan began more than 10 ka [1] and, since the arrival of the Spanish in the mid-1400's, eruptions have occurred in six eruptive clusters (1469, 1505, 1579, 1663, 1717, 1826-1856). Owing to its distance from population centers and the limited written record from 200 to 500 years ago, only an incomplete sample of the volcano's behavior is documented prior to the 1800's. The geologic record provides a more complete sample of the volcano's behavior since the 19th century. Geologic and historical data suggest that the intensity and pattern of activity at Atitlan Volcano is similar to that of Fuego Volcano, 44 km to the east, where active eruptions have been observed throughout the historical period. Because of Atitlan's moderately explosive nature and frequency of eruptions, there is a need for local and regional hazard planning and mitigation efforts. Tourism has flourished in the area; economic pressure has pushed agricultural activity higher up the slopes of Atitlan and closer to the source of possible future volcanic activity. This report summarizes the hazards posed by Atitlan Volcano in the event of renewed activity but does not imply that an eruption is imminent. However, the recognition of potential activity will facilitate hazard and emergency preparedness.

  10. Submarine volcanoes along the Aegean volcanic arc

    Science.gov (United States)

    Nomikou, Paraskevi; Papanikolaou, Dimitrios; Alexandri, Matina; Sakellariou, Dimitris; Rousakis, Grigoris

    2013-06-01

    The Aegean volcanic arc has been investigated along its offshore areas and several submarine volcanic outcrops have been discovered in the last 25 years of research. The basic data including swath bathymetric maps, air-gun profiles, underwater photos and samples analysis have been presented along the four main volcanic groups of the arc. The description concerns: (i) Paphsanias submarine volcano in the Methana group, (ii) three volcanic domes to the east of Antimilos Volcano and hydrothermal activity in southeast Milos in the Milos group, (iii) three volcanic domes east of Christiana and a chain of about twenty volcanic domes and craters in the Kolumbo zone northeast of Santorini in the Santorini group and (iv) several volcanic domes and a volcanic caldera together with very deep slopes of several volcanic islands in the Nisyros group. The tectonic structure of the volcanic centers is described and related to the geometry of the arc and the neotectonic graben structures that usually host them. The NE-SW direction is dominant in the Santorini and Nisyros volcanic groups, located at the eastern part of the arc, where strike-slip is also present, whereas NW-SE direction dominates in Milos and Methana at the western part, where co-existence of E-W disrupting normal faults is observed. The volcanic relief reaches 1100-1200 m in most cases. This is produced from the outcrops of the volcanic centers emerging usually at 400-600 m depth and ending either below sea level or at high altitudes of 600-700 m on the islands. Hydrothermal activity at relatively high temperatures observed in Kolumbo is remarkable whereas low temperature phenomena have been detected in the Santorini caldera around Kameni islands and in the area southeast of Milos. In Methana and Nisyros, hydrothermal activity seems to be limited in the coastal areas without other offshore manifestations.

  11. Mihi Breccia: A stack of lacustrine sediments and subaqueous pyroclastic flows within the Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Downs, Drew

    2016-01-01

    The Taupo Volcanic Zone (TVZ), New Zealand, encompasses a wide variety of arc-related strata, although most of its small-volume (non-caldera-forming) eruptions are poorly-exposed and extensively hydrothermally altered. The Mihi Breccia is a stratigraphic sequence consisting of interbedded rhyolitic pyroclastic flows and lacustrine sediments with eruption ages of 281 ± 18 to at least 239 ± 6 ka (uncertainties at 2σ). In contrast to other small-volume rhyolitic eruptions within the TVZ, Mihi Breccia is relatively well-exposed within the Paeroa fault block, and contains minimal hydrothermal alteration. Pyroclastic flow characteristics and textures including: 1) breadcrusted juvenile clasts, 2) lack of welding, 3) abundant ash-rich matrix, 4) lack of fiamme and eutaxitic textures, 5) lack of thermal oxidation colors, 6) lack of cooling joints, 7) exclusive lacustrine sediment lithic clasts, and 8) interbedding with lacustrine sediments, all indicating that Mihi Breccia strata originated in a paleo-lake system. This ephemeral paleo-lake system is inferred to have lasted for > 50 kyr (based on Mihi Breccia age constraints), and referred to as Huka Lake. Mihi Breccia pyroclastic flow juvenile clast geochemistry and petrography correspond with similar-aged (264 ± 8, 263 ± 10, and 247 ± 4 ka) intra-caldera rhyolite domes filling the Reporoa caldera (source of the 281 ± 81 Kaingaroa Formation ignimbrite). These exposed intra-caldera rhyolite domes (as well as geophysically inferred subsurface domes) are proposed to be source vents for the Mihi Breccia pyroclastic flows. Soft-sediment deformation associated with Mihi Breccia strata indicate either seismic shock, rapid sediment loading during pyroclastic flow emplacement, or both. Thus, the Mihi Breccia reflects a prolonged series of subaqueous rhyolite dome building and associated pyroclastic flows, accompanied by seismic activity, emplaced into a large paleo-lake system within the TVZ.

  12. Mihi Breccia: A stack of lacustrine sediments and subaqueous pyroclastic flows within the Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Downs, Drew T.

    2016-11-01

    The Taupo Volcanic Zone (TVZ), New Zealand, encompasses a wide variety of arc-related strata, although most of its small-volume (non-caldera-forming) eruptions are poorly-exposed and extensively hydrothermally altered. The Mihi Breccia is a stratigraphic sequence consisting of interbedded rhyolitic pyroclastic flows and lacustrine sediments with eruption ages of 281 ± 18 to at least 239 ± 6 ka (uncertainties at 2σ). In contrast to other small-volume rhyolitic eruptions within the TVZ, Mihi Breccia is relatively well-exposed within the Paeroa fault block, and contains minimal hydrothermal alteration. Pyroclastic flow characteristics and textures include: 1) prismatically jointed juvenile clasts, 2) lack of welding, 3) abundant ash-rich matrix, 4) lack of fiamme and eutaxitic textures, 5) lack of thermal oxidation colors, 6) lack of cooling joints, 7) exclusive lacustrine sediment lithic clasts, and 8) interbedding with lacustrine sediments, all indicating that Mihi Breccia strata originated in a paleo-lake system. This ephemeral paleo-lake system is inferred to have lasted for > 50 kyr (based on Mihi Breccia age constraints), and referred to as Huka Lake. Mihi Breccia pyroclastic flow juvenile clast geochemistry and petrography correspond with similar-aged (264 ± 8, 263 ± 10, and 247 ± 4 ka) intra-caldera rhyolite domes filling the Reporoa caldera (source of the 281 ka Kaingaroa Formation ignimbrite). These exposed intra-caldera rhyolite domes (as well as geophysically inferred subsurface domes) are proposed to be source vents for the Mihi Breccia pyroclastic flows. Soft-sediment deformation associated with Mihi Breccia strata indicates either seismic shock, rapid sediment loading during pyroclastic flow emplacement, or both. Thus, the Mihi Breccia reflects a prolonged series of subaqueous rhyolite dome building and associated pyroclastic flows, accompanied by seismic activity, emplaced into a large paleo-lake system within the TVZ.

  13. Imaging the Roots of Geothermal Systems: 3-D Inversion of Magnetotelluric Array Data in the Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Bertrand, E. A.; Caldwell, G.; Bannister, S. C.; Hill, G.; Bennie, S.

    2013-12-01

    The Taupo Volcanic Zone (TVZ), located in the central North Island of New Zealand, is a rifted arc that contains more than 20 liquid-dominated high-temperature geothermal systems, which together discharge ~4.2 GW of heat at the surface. The shallow (upper ~500 m) extent of these geothermal systems is marked by low-resistivity, mapped by tens-of-thousands of DC resistivity measurements collected throughout the 1970's and 80's. Conceptual models of heat transport through the brittle crust of the TVZ link these low-resistivity anomalies to the tops of vertically ascending plumes of convecting hydrothermal fluid. Recently, data from a 40-site array of broadband seismometers with ~4 km station spacing, and an array of 270 broadband magnetotelluric (MT) measurements with ~2 km station spacing, have been collected in the south-eastern part of the TVZ in an experiment to image the deep structure (or roots) of the geothermal systems in this region. Unlike DC resistivity, these MT measurements are capable of resolving the resistivity structure of the Earth to depths of 10 km or more. 2-D and 3-D models of subsets of these MT data have been used to provide the first-ever images of quasi-vertical low-resistivity zones (at depths of 3-7 km) that connect with the near-surface geothermal fields. These low-resistivity zones are interpreted to represent convection plumes of high-temperature fluids ascending within fractures, which supply heat to the overlying geothermal fields. At the Rotokawa, Ngatamariki and Ohaaki geothermal fields, these plumes extend to a broad layer of low-resistivity, inferred to represent a magmatic, basal heat source located below the seismogenic zone (at ~7-8 km depth) that drives convection in the brittle crust above. Little is known about the mechanisms that transfer heat into the hydrothermal regime. However, at Rotokawa, new 3-D resistivity models image a vertical low-resistivity zone that lies directly beneath the geothermal field. The top of this

  14. Geochemical variability of hydrothermal emissions between three Pacific volcanic arc systems: Alaskan-Aleutian and Cascadian, North America and Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Blackstock, J. M.; Horton, T. W.; Gravley, D. M.; Deering, C. D.

    2013-12-01

    Knowledge of the source, transport, and fate of hydrothermal fluids in the upper crust informs our understanding and interpretation of ore-forming processes, volcanogenic hazards, geothermal resources, and volatile cycling. Co-variation between fluid inclusion CO2/CH4 and N2/Ar ratios is an established tracer of magmatic, meteoric, and crustal fluid end-members. Yet, this tracer has had limited application to macroscopic fluid reservoirs accessible via geothermal wells and hydrothermal features (e.g. pools). In this study, we compared the covariance CO2/CH4 and N2/Ar ratios of gases collected throughout the Taupo Volcanic Zone, New Zealand (TVZ), the Alaska-Aleutian Volcanic Arc, USA (AAVA), and the Cascadian Volcanic Arc, USA (CVA) with corresponding δ13C and 3He/4He values. Our findings show that there is good agreement between these proxies for different end-member contributions at coarse scales. However, some samples classified as meteoric water according to the CO2/CH4 and N2/Ar ratios also show more positive δ13C values (~ -7.0 per mil) and relatively higher 3He/4He ratios indicative of magmatic input from primarily mantle sources. This unexpected result may be related to magmatic fluids, CO2 in particular, mixing with predominantly meteoric derived waters. The potential to identify magmatic CO2 in groundwater samples overlying geothermal systems in differing volcanic arc settings using simple and cost-effective gas ratios is a promising step forward in the search for ';surface blind' but developable geothermal systems and volcanic monitoring. 3He/4He anomalies also support this inference and underscore the potential decoupling of thermal anomalies and magmatic-derived fluids in the Earth's crust. The general agreement between the co-variation of CO2/CH4 and N2/Ar ratios with other isotope and geochemical proxies for magmatic, meteoric, and crustal end-members is encouraging to employ expanded use of these ratios for both the exploration and monitoring of

  15. Thermo-physical rock properties of greywacke basement rock and intrusive lavas from the Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Mielke, P.; Weinert, S.; Bignall, G.; Sass, I.

    2016-09-01

    Greywacke of the Waipapa and Torlesse (Composite) Terrane form the basement of the Taupo Volcanic Zone (TVZ), New Zealand. Together with inferred buried lavas, domes and igneous complexes they are likely to be the dominant rock type prevailing at depths > 4 km beneath the TVZ. A fundamental understanding of the rock properties of the deep formations is of utmost importance for the exploration of deep unconventional geothermal resources. An outcrop analogue study was conducted to improve the understanding of the thermo-physical rock properties of likely deep buried rock formations beneath the TVZ. A total of 145 core samples were taken at 10 locations inside and outside the TVZ and their grain and bulk density, porosity, matrix permeability, bulk thermal conductivity and specific heat capacity, and the compressional and shear wave velocities measured on oven-dry samples. Additional tests of the unconfined compressive strength were conducted for selected greywacke samples to quantify their mechanical rock strength. The obtained data indicates that the thermo-physical rock properties are mainly controlled by porosity, and minor by mineralogy, texture and grain size. Samples from Waipapa-type and Torlesse-type greywacke exhibit minor rheological differences, with Waipapa-type greywacke having lowest porosity (about 1% vs. 3%) and highest bulk thermal conductivity (2.5 W m- 1 K- 1 vs. 1.7 W m- 1 K- 1) and specific heat capacity (0.8 kJ kg- 1 K- 1 vs. 0.7 kJ kg- 1 K- 1). Matrix permeability is rock properties due to their wide range of porosity (rock properties were tested at laboratory conditions (ambient temperature and pressure), which do not reflect the in situ conditions at greater depth. With depth, thermal conductivity and acoustic wave velocity are likely to decrease caused by micro fractures resulting from thermal cracking of the rock, while specific heat capacity increases. The data presented in this paper are expected to improve the statistical confidence on

  16. Surface heat flow and CO2 emissions within the Ohaaki hydrothermal field, Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Rissmann, C.; Christenson, B.; Werner, C.; Leybourne, M.; Cole, J.; Gravley, D.

    2012-01-01

    Carbon dioxide emissions and heat flow have been determined from the Ohaaki hydrothermal field, Taupo Volcanic Zone (TVZ), New Zealand following 20a of production (116MW e). Soil CO2 degassing was quantified with 2663 CO2 flux measurements using the accumulation chamber method, and 2563 soil temperatures were measured and converted to equivalent heat flow (Wm -2) using published soil temperature heat flow functions. Both CO2 flux and heat flow were analysed statistically and then modelled using 500 sequential Gaussian simulations. Forty subsoil CO 2 gas samples were also analysed for stable C isotopes. Following 20a of production, current CO2 emissions equated to 111??6.7T/d. Observed heat flow was 70??6.4MW, compared with a pre-production value of 122MW. This 52MW reduction in surface heat flow is due to production-induced drying up of all alkali-Cl outflows (61.5MW) and steam-heated pools (8.6MW) within the Ohaaki West thermal area (OHW). The drying up of all alkali-Cl outflows at Ohaaki means that the soil zone is now the major natural pathway of heat release from the high-temperature reservoir. On the other hand, a net gain in thermal ground heat flow of 18MW (from 25MW to 43.3??5MW) at OHW is associated with permeability increases resulting from surface unit fracturing by production-induced ground subsidence. The Ohaaki East (OHE) thermal area showed no change in distribution of shallow and deep soil temperature contours despite 20a of production, with an observed heat flow of 26.7??3MW and a CO 2 emission rate of 39??3T/d. The negligible change in the thermal status of the OHE thermal area is attributed to the low permeability of the reservoir beneath this area, which has limited production (mass extraction) and sheltered the area from the pressure decline within the main reservoir. Chemistry suggests that although alkali-Cl outflows once contributed significantly to the natural surface heat flow (~50%) they contributed little (99% of the original CO 2

  17. The geochemistry of lithium-bearing geothermal water, Taupo Volcanic Zone, and shallow fluid processes in a very active silicic volcanic arc

    Science.gov (United States)

    Dean, A. S.; Hoskin, P. W.; Rudnick, R. L.; Liu, X.; Boseley, C.

    2011-12-01

    The Li abundances and isotopic systematics of Taupo Volcanic Zone (TVZ) geothermal fluids preserves a record of processes occurring within shallow portions of geothermal reservoirs as well as deeper portions of the arc crust. Understanding Li cycling and isotopic fractionation in TVZ geothermal systems contributes to a more refined understanding of physicochemical processes affecting New Zealand's geothermal resources. A comprehensive dataset of 73 samples was compiled, with samples collected from geothermal surface features (springs, spouters, geysers, etc.) and electric-power industry production wells, collectively representing18 geothermal fields across the breadth and width the TVZ. No comparable dataset of fluid analyses exists. Ion chromatography, AAS, and quadrupole ICP-MS analyses were done for Li, Cl-, SiO2, SO42- K, Na, Ca, Mg, B, Sr and Pb concentrations. Lithium abundance in geothermal fluids from the TVZ have a dataset-wide average of 5.9 mg/L and range 4 μg/L to 29 mg/L. The Li abundance and Li/Cl ratios for geothermal water and steam condensates vary systematically as a result of boiling, mixing, and water/rock reaction. Lithium abundance and Li/Cl ratios are, therefore, indicators of shallow (above 2.5 km) and locally variable reservoir processes. δ7Li analysis of 63 samples was performed at the University of Maryland, College Park. Data quality was controlled by measurement of L-SVEC as a calibration standard and by multiple analysis of selected samples. The average δ7Li value for TVZ geothermal fluids is -0.8%. Most δ7Li values for geothermal water fall within a small range of about -3% to+2% indicating similar processes are causing similar isotopic fractionation throughout the region. Considered together, Li aundances and δ7Li values, in combination with numerical models, indicate possible evolution pathways and water/rock reactions in TVZ geothermal systems. Models based on rocks and surface water analysis indicate that Li cycles and

  18. Temperature and pH control on lipid composition of silica sinters from diverse hot springs in the Taupo Volcanic Zone, New Zealand.

    Science.gov (United States)

    Kaur, Gurpreet; Mountain, Bruce W; Stott, Matthew B; Hopmans, Ellen C; Pancost, Richard D

    2015-03-01

    Microbial adaptations to environmental extremes, including high temperature and low pH conditions typical of geothermal settings, are of interest in astrobiology and origin of life investigations. The lipid biomarkers preserved in silica deposits associated with six geothermal areas in the Taupo Volcanic Zone were investigated and variations in lipid composition as a function of temperature and pH were assessed. Lipid analyses reveal highly variable abundances and distributions, reflecting community composition as well as adaptations to extremes of pH and temperature. Biomarker profiles reveal three distinct microbial assemblages across the sites: the first in Champagne Pool and Loop Road, the second in Orakei Korako, Opaheke and Ngatamariki, and the third in Rotokawa. Similar lipid distributions are observed in sinters from physicochemically similar springs. Furthermore, correlation between lipid distributions and geothermal conditions is observed. The ratio of archaeol to bacterial diether abundance, bacterial diether average chain length, degree of GDGT cyclisation and C31 and C32 hopanoic acid indices typically increase with temperature. At lower pH, the ratio of archaeol to bacterial diethers, degree of GDGT cyclisation and C31 and C32 hopanoic acid indices are typically higher. No trends in fatty acid distributions with temperature or pH are evident, likely reflecting overprinting due to population influences.

  19. Volcanic Activities of Hakkoda Volcano after the 2011 Tohoku Earthquake

    Science.gov (United States)

    Yamamoto, M.; Miura, S.

    2014-12-01

    The 2011 Tohoku Earthquake of 11 March 2011 generated large deformation in and around the Japanese islands, and the large crustal deformation raises fear of further disasters including triggered volcanic activities. In this presentation, as an example of such potential triggered volcanic activities, we report the recent seismic activities of Hakkoda volcano, and discuss the relation to the movement of volcanic fluids. Hakkoda volcano is a group of stratovolcanoes at the northern end of Honshu Island, Japan. There are fumaroles and hot springs around the volcano, and phreatic eruptions from Jigoku-numa on the southwestern flank of Odake volcano, which is the highest peak of the volcanic group, were documented in its history. Since just after the occurrence of the Tohokui Earthquake, the seismicity around the volcano became higher, and the migration of hypocenters of volcano-tectonic (VT) earthquakes was observed.In addition to these VT earthquakes, long-period (LP) events started occurring beneath Odake at a depth of about 2-3 km since February, 2013, and subtle crustal deformation caused by deep inflation source was also detected by the GEONET GNSS network around the same time. The spectra of LP events are common between events irrespective of the magnitude of events, and they have several spectral peaks at 6-7 sec, 2-3 sec, 1 sec, and so on. These LP events sometimes occur like a swarm with an interval of several minutes. The characteristics of observed LP events at Hakkoda volcano are similar to those of LP events at other active volcanoes and hydrothermal area in the world, where abundant fluids exist. Our further analysis using far-field Rayleigh radiation pattern observed by NIED Hi-net stations reveals that the source of LP events is most likely to be a nearly vertical tensile crack whose strike is NE-SW direction. The strike is almost perpendicular to the direction of maximum extensional strain estimated from the geodetic analysis, and is almost parallel to

  20. Mixing and mingling in the evolution of andesite dacite magmas; evidence from co-magmatic plutonic enclaves, Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Cole, J. W.; Gamble, J. A.; Burt, R. M.; Carroll, L. D.; Shelley, D.

    2001-10-01

    The southeastern side of the Taupo Volcanic Zone, New Zealand is marked by a line of andesite/dacite/low-silica rhyolite complexes. Co-magmatic plutonic enclaves occur within the lavas of the four youngest complexes: White Island, Motuhora (Whale Island), Edgecumbe and Tauhara. The enclaves range from coarse-grained gabbros, diorites, granodiorites and a syenite to finer-grained dolerites and microdiorites. The more mafic types are generally porphyritic with large phenocrysts of plagioclase, usually with extensive sieve textures in the cores and corroded margins. Most of these enclaves, including the coarser-grained plutonic examples, contain glass and many are miarolitic. Diorites and microdiorites/dolerites predominate at White Island, Motuhora and Edgecumbe; many are porphyritic. Enclaves at Tauhara are more variable; those collected from Hipaua Dome include a range from microdiorites to quartz microdiorites and those from Rubbish Tip Dome include microdiorites, a granodiorite, and a syenite. Most enclaves show textural evidence for disequilibrium with multiple populations of plagioclase and pyroxene. They also show considerable textural variation, even within a thin section, with coarse-grained gabbros/diorites intimately mixed with finer-grained dolerites/microdiorites. Geochemically and isotopically, most enclaves have a similar composition with their host lavas, although some have lower silica contents. Enclaves at Motuhora and Tauhara are isotopically more variable, indicating multiple sources and a more complex petrogenesis. Most diorite/microdiorite enclaves are interpreted to represent parts of a crystal mush formed during fractionation of andesite/dacite magma, and entrained during later rise of magma to the surface. The granodiorite from Rubbish Tip Dome, Tauhara, probably represents part of a silicic magma chamber within the crust that fed the host low-silica rhyolite lava dome. Variability within the enclaves indicates the complexity likely to occur

  1. Volcanic Environments Monitoring by Drones Mud Volcano Case Study

    Science.gov (United States)

    Amici, S.; Turci, M.; Giulietti, F.; Giammanco, S.; Buongiorno, M. F.; La Spina, A.; Spampinato, L.

    2013-08-01

    Volcanic activity has often affected human life both at large and at small scale. For example, the 2010 Eyjafjallajokull eruption caused severe economic damage at continental scale due to its strong effect on air traffic. At a local scale, ash fall and lava flow emission can cause harm and disruption. Understanding precursory signals to volcanic eruptions is still an open and tricky challenge: seismic tremor and gas emissions, for example, are related to upcoming eruptive activity but the mechanisms are not yet completely understood. Furthermore, information related to gases emission mostly comes from the summit crater area of a volcano, which is usually hard to investigate with required accuracy. Although many regulation problems are still on the discussion table, an increasing interest in the application of cutting-edge technology like unmanned flying systems is growing up. In this sense, INGV (Istituto Nazionale di Geofisica e Vulcanologia) started to investigate the possibility to use unmanned air vehicles for volcanic environment application already in 2004. A flight both in visual- and radio-controlled mode was carried out on Stromboli volcano as feasibility test. In this work we present the preliminary results of a test performed by INGV in collaboration with the University of Bologna (aerospace division) by using a multi-rotor aircraft in a hexacopter configuration. Thermal camera observations and flying tests have been realised over a mud volcano located on its SW flank of Mt. Etna and whose activity proved to be related to early stages of magma accumulation within the volcano.

  2. Volcanoes

    Science.gov (United States)

    ... or more from a volcano. Before a Volcanic Eruption The following are things you can do to ... in case of an emergency. During a Volcanic Eruption Follow the evacuation order issued by authorities and ...

  3. Volcanic tremor and plume height hysteresis from Pavlof Volcano, Alaska.

    Science.gov (United States)

    Fee, David; Haney, Matthew M; Matoza, Robin S; Eaton, Alexa R; Cervelli, Peter; Schneider, David J; Iezzi, Alexandra M

    2017-01-06

    The March 2016 eruption of Pavlof Volcano, Alaska, produced an ash plume that caused the cancellation of more than 100 flights in North America. The eruption generated strong tremor that was recorded by seismic and remote low-frequency acoustic (infrasound) stations, including the EarthScope Transportable Array. The relationship between the tremor amplitudes and plume height changes considerably between the waxing and waning portions of the eruption. Similar hysteresis has been observed between seismic river noise and discharge during storms, suggesting that flow and erosional processes in both rivers and volcanoes can produce irreversible structural changes that are detectable in geophysical data. We propose that the time-varying relationship at Pavlof arose from changes in the tremor source related to volcanic vent erosion. This relationship may improve estimates of volcanic emissions and characterization of eruption size and intensity.

  4. Evaluation of volcanic risk management in Merapi and Bromo Volcanoes

    Science.gov (United States)

    Bachri, S.; Stöetter, J.; Sartohadi, J.; Setiawan, M. A.

    2012-04-01

    Merapi (Central Java Province) and Bromo (East Java Province) volcanoes have human-environmental systems with unique characteristics, thus causing specific consequences on their risk management. Various efforts have been carried out by many parties (institutional government, scientists, and non-governmental organizations) to reduce the risk in these areas. However, it is likely that most of the actions have been done for temporary and partial purposes, leading to overlapping work and finally to a non-integrated scheme of volcanic risk management. This study, therefore, aims to identify and evaluate actions of risk and disaster reduction in Merapi and Bromo Volcanoes. To achieve this aims, a thorough literature review was carried out to identify earlier studies in both areas. Afterward, the basic concept of risk management cycle, consisting of risk assessment, risk reduction, event management and regeneration, is used to map those earlier studies and already implemented risk management actions in Merapi and Bromo. The results show that risk studies in Merapi have been developed predominantly on physical aspects of volcanic eruptions, i.e. models of lahar flows, hazard maps as well as other geophysical modeling. Furthermore, after the 2006 eruption of Merapi, research such on risk communication, social vulnerability, cultural vulnerability have appeared on the social side of risk management research. Apart from that, disaster risk management activities in the Bromo area were emphasizing on physical process and historical religious aspects. This overview of both study areas provides information on how risk studies have been used for managing the volcano disaster. This result confirms that most of earlier studies emphasize on the risk assessment and only few of them consider the risk reduction phase. Further investigation in this field work in the near future will accomplish the findings and contribute to formulate integrated volcanic risk management cycles for both

  5. Database for volcanic processes and geology of Augustine Volcano, Alaska

    Science.gov (United States)

    McIntire, Jacqueline; Ramsey, David W.; Thoms, Evan; Waitt, Richard B.; Beget, James E.

    2012-01-01

    Augustine Island (volcano) in lower Cook Inlet, Alaska, has erupted repeatedly in late-Holocene and historical times. Eruptions typically beget high-energy volcanic processes. Most notable are bouldery debris avalanches containing immense angular clasts shed from summit domes. Coarse deposits of these avalanches form much of Augustine's lower flanks. This geologic map at 1:25,000 scale depicts these deposits, these processes.

  6. Hydrothermal reservoir beneath Taal Volcano (Philippines): Implications to volcanic activity

    Science.gov (United States)

    Nagao, T.; Alanis, P. B.; Yamaya, Y.; Takeuchi, A.; Bornas, M. V.; Cordon, J. M.; Puertollano, J.; Clarito, C. J.; Hashimoto, T.; Mogi, T.; Sasai, Y.

    2012-12-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The first recorded eruption was in 1573. Since then it has erupted 33 times resulting in thousands of casualties and large damages to property. In 1995, it was declared as one of the 15 Decade Volcanoes. Beginning in the early 1990s it has experienced several phases of abnormal activity, including seismic swarms, episodes of ground deformation, ground fissuring and hydrothermal activities, which continues up to the present. However, it has been noted that past historical eruptions of Taal Volcano may be divided into 2 distinct cycles, depending on the location of the eruption center, either at Main Crater or at the flanks. Between 1572-1645, eruptions occurred at the Main Crater, in 1707 to 1731, they occurred at the flanks. In 1749, eruptions moved back to the Main Crater until 1911. During the 1965 and until the end of the 1977 eruptions, eruptive activity once again shifted to the flanks. As part of the PHIVOLCS-JICA-SATREPS Project magnetotelluric and audio-magnetotelluric surveys were conducted on Volcano Island in March 2011 and March 2012. Two-dimensional (2-D) inversion and 3-D forward modeling reveals a prominent and large zone of relatively high resistivity between 1 to 4 kilometers beneath the volcano almost directly beneath the Main Crater, surrounded by zones of relatively low resistivity. This anomalous zone of high resistivity is hypothesized to be a large hydrothermal reservoir filled with volcanic fluids. The presence of this large hydrothermal reservoir could be related to past activities of Taal Volcano. In particular we believe that the catastrophic explosion described during the 1911 eruption was the result of the hydrothermal reservoir collapsing. During the cycle of Main Crater eruptions, this hydrothermal reservoir is depleted, while during a cycle of flank eruptions this reservoir is replenished with hydrothermal fluids.

  7. Tectonic localization of multi-plume hydrothermal fluid flow in a segmented rift system, Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Rowland, J. V.; Downs, D. T.; Scholz, C.; de P. S. Zuquim, M.

    2013-05-01

    High-temperature (>250°C) multi-plume hydrothermal systems occur in a range of tectonic settings, though most are extensional or transtensional. A key feature of such settings is their tendency to partition into discrete structural elements that scale with the thickness of the seismogenic zone. The late Miocene to present record of arc magmatism and rifting in the North Island of New Zealand illustrates the importance of structural segmentation and reactivation of inherited basement fabrics on the localisation of hydrothermal upflow. The 15 My record of similarly-oriented magmatism, rifting and hydrothermal activity associated with subduction of the Pacific Plate beneath the North Island of New Zealand. Lateral migration of the locus of arc magmatism, concomitant with roll-back of the subducting slab, is supported by the SE-directed younging of: 1) volcanism; 2) fault-controlled rift basins; and 3) hydrothermal activity, represented by the distribution of epithermal mineralisation within the ~15-3 Ma Coromandel Volcanic Zone (CVZ), and geothermal activity within the TVZ. Currently the TVZ is extending in a NW-SE direction at a rate that varies from ~3 mm/yr to ~15 mm/yr from SW to NE, respectively. The TVZ is partitioned into discrete rift segments, comprising arrays of NE-striking normal faults of ~20 km in length, as expected on mechanical grounds for the 6-8 km-thick seismogenic zone. Transfer zones between rift segments coincide with N-to-NW-trending alignments of geothermal fields, spaced ~ 30 km apart can be recognized elsewhere within the CVZ. The most productive epithermal deposits to date are localised where these inferred transfer zones intersect arc-parallel fault arrays. A similar tectonic configuration occurs in the Deseado Massif, Argentinian Patagonia, where interplay between transfer and rift faults is inferred to have localized hydrothermal fluids in small pull-apart basins and arrays of extension veins for durations >30 My.

  8. Temperature and pH control on lipid composition of silica sinters from diverse hot springs in the Taupo Volcanic Zone, New Zealand

    NARCIS (Netherlands)

    Kaur, G.; Mountain, B.W.; Stott, M.; Hopmans, E.C.; Pancrost, R.J.

    2015-01-01

    Microbial adaptations to environmental extremes, including high temperature and low pH conditions typical of geothermal settings, are of interest in astrobiology and origin of life investigations. The lipid biomarkers preserved in silica deposits associated with six geothermal areas in the Taupo Vol

  9. Studying monogenetic volcanoes with Terrestrial Laser Scanner: Case study at Croscat volcano (Garrotxa Volcanic Zone, Spain)

    Science.gov (United States)

    Geyer Traver, A.; Garcia-Selles, D.; Peddrazzi, D.; Barde-Cabusson, S.; Marti, J.; Muñoz, J.

    2013-12-01

    Monogenetic basaltic zones are common in many volcanic environments and may develop under very different geodynamic conditions. Despite existing clear similarities between the eruptive activity of different monogenetic volcanic fields, important distinctions may arise when investigating in detail the individual eruptive sequences. Interpretation of the deposits and consequently, the reconstruction and characterization of these eruptive sequences is crucial to evaluate the potential hazard in case of active areas. In diverse occasions, erosional processes (natural and/or anthropogenic) may partly destroy these relatively small-sized volcanic edifices exposing their internal parts. Furthermore, despite human activity in volcanic areas is sometimes unimportant due to the remote location of the monogenetic cones, there are places where this form of erosion is significant, e.g. Croscat volcano (Catalan Volcanic Field, Spain). In any case, when studying monogenetic volcanism, it is usual to find outcrops where the internal structure of the edifices is, for one or other reason, well exposed. However, the access to these outcrops may be extremely difficult or even impossible. During the last years, it has been demonstrated that the study of outcrops with problematic or completely restricted access can be carried out by means of digital representations of the outcrop surface. Digital outcrops make possible the study of those areas with natural access limitations or safety issues and may facilitate visualization of the features of interest over the entire outcrop, as long as the digital outcrop can be analysed while navigated in real- time, with optional displays for perspective, scale distortions, and attribute filtering. In particular, Terrestrial Laser Scanning (TSL) instruments using Light Detection And Ranging technology (LIDAR) are capable of capturing topographic details and achieve modelling accuracy within a few centimetres. The data obtained enables the creation of

  10. Large magnitude silicic volcanism in north Afar: the Nabro Volcanic Range and Ma'alalta volcano

    Science.gov (United States)

    Wiart, Pierre; Oppenheimer, Clive

    2005-02-01

    Much of the volcanological work carried out in north Afar (Ethiopia and Eritrea) has focused on the nature of Quaternary basaltic volcanic ranges, which have been interpreted by some as incipient oceanic ridges. However, we show here that comparable volumes of silicic magmas have been erupted in the region. In particular, the virtually undocumented Nabro Volcanic Range, which runs NNE for more than 100 km from the margin of the Danakil Depression to the Red Sea coast, has a subaerial volume of the order of 550 km3, comparable to the volume of the much better known Erta’Ale axial volcanic range. Nabro volcano itself forms part of an enigmatic double caldera structure with a neighbouring volcano, Mallahle. The twin caldera may have formed simultaneously with the eruption of between 20 and 100 km3 of ignimbrite, which is readily identified in Landsat Thematic Mapper imagery. This may have been the largest explosive eruption in north Afar, and is certain to have deposited a regionally distributed tephra layer which could in the future be located in distal sections as a stratigraphic marker. An integrated analysis of optical and synthetic aperture radar imagery, digital topographic data, field observations and limited geochemical measurements, permits here descriptions and first order inferences about the structure, stratigraphy and compositions of several major volcanoes of the Afar Triangle, and a reappraisal of their regional significance.

  11. 2014 volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Cameron, Cheryl E.; Dixon, James P.; Neal, Christina A.; Waythomas, Christopher F.; Schaefer, Janet R.; McGimsey, Robert G.

    2017-09-07

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2014. The most notable volcanic activity consisted of intermittent ash eruptions from long-active Cleveland and Shishaldin Volcanoes in the Aleutian Islands, and two eruptive episodes at Pavlof Volcano on the Alaska Peninsula. Semisopochnoi and Akutan volcanoes had seismic swarms, both likely the result of magmatic intrusion. The AVO also installed seismometers and infrasound instruments at Mount Cleveland during 2014.

  12. Volcanic gas impacts on vegetation at Turrialba Volcano, Costa Rica

    Science.gov (United States)

    Teasdale, R.; Jenkins, M.; Pushnik, J.; Houpis, J. L.; Brown, D. L.

    2010-12-01

    Turrialba volcano is an active composite stratovolcano that is located approximately 40 km east of San Jose, Costa Rica. Seismic activity and degassing have increased since 2005, and gas compositions reflect further increased activity since 2007 peaking in January 2010 with a phreatic eruption. Gas fumes dispersed by trade winds toward the west, northwest, and southwest flanks of Turrialba volcano have caused significant vegetation kill zones, in areas important to local agriculture, including dairy pastures and potato fields, wildlife and human populations. In addition to extensive vegetative degradation is the potential for soil and water contamination and soil erosion. Summit fumarole temperatures have been measured over 200 degrees C and gas emissions are dominated by SO2; gas and vapor plumes reach up to 2 km (fumaroles and gases are measured regularly by OVSICORI-UNA). A recent network of passive air sampling, monitoring of water temperatures of hydrothermal systems, and soil pH measurements coupled with measurement of the physiological status of surrounding plants using gas exchange and fluorescence measurements to: (1) identify physiological correlations between leaf-level gas exchange and chlorophyll fluorescence measurements of plants under long term stress induced by the volcanic gas emissions, and (2) use measurements in tandem with remotely sensed reflectance-derived fluorescence ratio indices to track natural photo inhibition caused by volcanic gas emissions, for use in monitoring plant stress and photosynthetic function. Results may prove helpful in developing potential land management strategies to maintain the biological health of the area.

  13. Update of the volcanic risk map of Colima volcano, Mexico

    Science.gov (United States)

    Suarez-Plascencia, C.; Nuñez Cornu, F. J.; Marquez-Azua, B.

    2010-12-01

    The Colima volcano, located in western Mexico (19° 30.696 N, 103° 37.026 W) began its current eruptive process in February 10, 1999. This event was the basis for the development of two volcanic hazard maps: one for ballistics (rock fall) lahars, and another one for ash fall. During the period of 2003 to 2008 this volcano has had an intense effusive-explosive activity, similar to the one that took place during the period of 1890 through 1900. Intense pre-Plinian eruption in January 20, 1913, generated little economic losses in the lower parts of the volcano thanks to the low population density and low socio-economic activities at the time The current volcanic activity has triggered ballistic projections, pyroclastic and ash flows, and lahars, all have exceeded the maps limits established in 1999. Vulnerable elements within these areas have gradually changed due to the expansion of the agricultural frontier on the east and southeast sides of the Colima volcano. On the slopes of the northwest side, new blue agave Tequilana weber and avocado orchard crops have emerged along with important production of greenhouse tomato, alfalfa and fruit (citrus) crops that will eventually be processed and dried for exportation to the United States and Europe. Also, in addition to the above, large expanses of corn and sugar cane have been planted on the slopes of the volcano since the nineteenth century. The increased agricultural activity has had a direct impact in the reduction of the available forest land area. Coinciding with this increased activity, the 0.8% growth population during the period of 2000 - 2005, - due to the construction of the Guadalajara-Colima highway-, also increased this impact. The growth in vulnerability changed the level of risk with respect to the one identified in the year 1999 (Suarez, 2000), thus motivating us to perform an update to the risk map at 1:25,000 using vector models of the INEGI, SPOT images of different dates, and fieldwork done in order

  14. Late Holocene volcanism at Medicine Lake Volcano, northern California Cascades

    Science.gov (United States)

    Donnelly-Nolan, Julie M.; Champion, Duane E.; Grove, Timothy L.

    2016-05-23

    Late Holocene volcanism at Medicine Lake volcano in the southern Cascades arc exhibited widespread and compositionally diverse magmatism ranging from basalt to rhyolite. Nine well-characterized eruptions have taken place at this very large rear-arc volcano since 5,200 years ago, an eruptive frequency greater than nearly all other Cascade volcanoes. The lavas are widely distributed, scattered over an area of ~300 km2 across the >2,000-km2 volcano. The eruptions are radiocarbon dated and the ages are also constrained by paleomagnetic data that provide strong evidence that the volcanic activity occurred in three distinct episodes at ~1 ka, ~3 ka, and ~5 ka. The ~1-ka final episode produced a variety of compositions including west- and north-flank mafic flows interspersed in time with fissure rhyolites erupted tangential to the volcano’s central caldera, including the youngest and most spectacular lava flow at the volcano, the ~950-yr-old compositionally zoned Glass Mountain flow. At ~3 ka, a north-flank basalt eruption was followed by an andesite eruption 27 km farther south that contains quenched basalt inclusions. The ~5-ka episode produced two caldera-focused dacitic eruptions. Quenched magmatic inclusions record evidence of intrusions that did not independently reach the surface. The inclusions are present in five andesitic, dacitic, and rhyolitic host lavas, and were erupted in each of the three episodes. Compositional and mineralogic evidence from mafic lavas and inclusions indicate that both tholeiitic (dry) and calcalkaline (wet) parental magmas were present. Petrologic evidence records the operation of complex, multi-stage processes including fractional crystallization, crustal assimilation, and magma mixing. Experimental evidence suggests that magmas were stored at 3 to 6 km depth prior to eruption, and that both wet and dry parental magmas were involved in generating the more silicic magmas. The broad distribution of eruptive events and the relative

  15. Volcanic structure and composition of Old Shiveluch volcano, Kamchatka

    Science.gov (United States)

    Gorbach, Natalia; Portnyagin, Maxim; Tembrel, Igor

    2013-08-01

    This paper reports results of a new comprehensive geological mapping of the Late Pleistocene Old Shiveluch volcano. The mapping results and geochemical data on major and trace element composition of the volcanic rocks are used to characterize spatial distribution, eruptive sequence and volumetric relationships between different rock types of the volcano. Old Shiveluch volcano had been constructed during two main stages: initial explosive and subsequent effusive ones. Pyroclastic deposits of the initial stage are represented by agglomerate and psephytic tuffs with very few lava flows and form at least 60% of volume of the Old Shiveluch edifice. The deposits of the second stage are dominantly lava flows erupted from four vents: Central, Western, Baidarny and Southern, reconstructed from the field relationships of their lava flows. About 75% of the Old Shiveluch edifice, both pyroclastic deposits and lava, are composed of magnesian andesites (SiO2 = 57.3-63.8 wt.%, Mg# = 0.53-0.57). The most abundant andesitic lavas were coevally erupted from the Central and Western vents in the central part of the edifice. Less voluminous high-Al basaltic andesites (SiO2 = 53.5-55.7 wt.%, Mg# = 0.52-0.56) were produced by the Western, Baidarny and Southern vents situated in the south-western sector. Small volume high-Mg basaltic andesites (SiO2 = 53.9-55.0 wt.%, Mg# = 0.59-0.64) occur in the upper part of the pyroclastic deposits. Andesites of Old and Young Shiveluch Volcanoes have similar compositions, whereas Old Shiveluch basaltic andesites are compositionally distinctive from those of the Young Shiveluch by having lower Mg#, SiO2, Cr and Ni, and higher Al2O3, FeOT, CaO, TiO2, and V contents at given MgO. Geochemical modeling suggests that the compositions of the intermediate Old Shiveluch magmas can be reasonably explained by simple fractional crystallization of olivine, clinopyroxene, plagioclase and magnetite (± hornblende) from water-bearing (~ 3 wt.% H2O) high-Mg# basaltic

  16. Evolution and genesis of volcanic rocks from Mutnovsky Volcano, Kamchatka

    Science.gov (United States)

    Simon, A.; Yogodzinski, G. M.; Robertson, K.; Smith, E.; Selyangin, O.; Kiryukhin, A.; Mulcahy, S. R.; Walker, J. D.

    2014-10-01

    This study presents new geochemical data for Mutnovsky Volcano, located on the volcanic front of the southern portion of the Kamchatka arc. Field relationships show that Mutnovsky Volcano is comprised of four distinct stratocones, which have grown over that past 80 ka. The youngest center, Mutnovsky IV, has produced basalts and basaltic andesites only. The three older centers (Mutnovsky I, II, III) are dominated by basalt and basaltic andesite (60-80% by volume), but each has also produced small volumes of andesite and dacite. Across centers of all ages, Mutnovsky lavas define a tholeiitic igneous series, from 48-70% SiO2. Basalts and basaltic andesites have relatively low K2O and Na2O, and high FeO* and Al2O3 compared to volcanic rocks throughout Kamchatka. The mafic lavas are also depleted in the light rare earth elements (REEs), with chondrite-normalized La/Sm arc volcanic rocks worldwide. Radiogenic isotope ratios (Sr, Nd, Pb, Hf) are similar for samples from all four eruptive centers, and indicate that all samples were produced by melting of a similar source mixture. No clear age-progressive changes are evident in the compositions of Mutnovsky lavas. Mass balance and assimilation-fractional crystallization (AFC) modeling of major and rare earth elements (REEs) indicate that basaltic andesites were produced by FC of plagioclase, clinopyroxene and olivine from a parental basalt, combined with assimilation of a melt composition similar to dacite lavas present at Mutnovsky. This modeling also indicates that andesites were produced by FC of plagioclase from basaltic andesite, combined with assimilation of dacite. Dacites erupted from Mutnovsky I and II have low abundances of REEs, and do not appear to be related to mafic magmas by FC or AFC processes. These dacites are modeled as the products of dehydration partial melting at mid-crustal levels of a garnet-free, amphibole-bearing basaltic rock, which itself formed in the mid-crust by emplacement of magma that

  17. Volcanic tremor associated with eruptive activity at Bromo volcano

    Directory of Open Access Journals (Sweden)

    E. Gottschämmer

    1999-06-01

    Full Text Available Three broadband stations were deployed on Bromo volcano, Indonesia, from September to December 1995. The analysis of the seismograms shows that the signals produced by the volcanic sources cover the frequency range from at least 25 Hz down to periods of several minutes and underlines, therefore, the importance of broadband recordings. Frequency analysis reveals that the signal can be divided into four domains. In the traditional frequency range of volcanic tremor (1-10 Hz sharp transitions between two distinct values of the tremor amplitude can be observed. Additional tremor signal including frequencies from 10 to 20 Hz could be found during late November and early December. Throughout the whole experiment signals with periods of some hundred seconds were observed which are interpreted as ground tilts. For these long-period signals a particle motion analysis was performed in order to estimate the source location. Depth and radius can be estimated when the source is modeled as a sudden pressure change in a sphere. The fourth frequency range lies between 0.1 and 1 Hz and is dominated by two spectral peaks which are due to marine microseism. The phase velocity and the direction of wave propagation of these signals could be determined using the tripartite-method.

  18. Laboratory Studies of Ice Nucleation on Volcanic Ash

    Science.gov (United States)

    Tolbert, M. A.; Schill, G. P.; Genareau, K. D.

    2014-12-01

    Ice nucleation on volcanic ash controls both ash aggregation and cloud glaciation, which affect human respiratory health, atmospheric transport, and global climate. We have performed laboratory studies of the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman Microscopy coupled to an environmental cell. Ash from the Fuego (Basaltic Ash, Guatemala), Soufriere Hills (Andesetic Ash, Montserrat), and Taupo (Rhyolitic Ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. We find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice at ice saturation ratios of 1.05 ± 0.1. For immersion freezing, however, only the Taupo ash exhibited efficient heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

  19. 2010 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Neal, Christina A.; Herrick, Julie; Girina, O.A.; Chibisova, Marina; Rybin, Alexander; McGimsey, Robert G.; Dixon, Jim

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest at 12 volcanic centers in Alaska during 2010. The most notable volcanic activity consisted of intermittent ash emissions from long-active Cleveland volcano in the Aleutian Islands. AVO staff also participated in hazard communication regarding eruptions or unrest at seven volcanoes in Russia as part of an ongoing collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  20. 2013 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Dixon, James P.; Cameron, Cheryl; McGimsey, Robert G.; Neal, Christina A.; Waythomas, Chris

    2015-08-14

    The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2013. Beginning with the 2013 AVO Summary of Events, the annual description of the AVO seismograph network and activity, once a stand-alone publication, is now part of this report. Because of this change, the annual summary now contains an expanded description of seismic activity at Alaskan volcanoes. Eruptions occurred at three volcanic centers in 2013: Pavlof Volcano in May and June, Mount Veniaminof Volcano in June through December, and Cleveland Volcano throughout the year. None of these three eruptive events resulted in 24-hour staffing at AVO facilities in Anchorage or Fairbanks.

  1. A Preliminary Study of the Types of Volcanic Earthquakes and Volcanic Activity at the Changbaishan Tianchi Volcano

    Institute of Scientific and Technical Information of China (English)

    Ming Yuehong; Su Wei; Fang Lihua

    2006-01-01

    Since 2002, a significant increase in seismicity, obvious ground deformation and geochemical anomalies have been observed in the Changbaishan Tianchi volcanic area. A series felt earthquakes occur near the caldera, causing great influence to society. In this paper, the types of volcanic earthquakes recorded by the temporal seismic network since 2002 have been classified by analyzing the spectrum, time-frequency characteristics and seismic waveforms at different stations. The risk of volcano eruptions was also estimated. Our results show that almost all earthquakes occurring in Tianchi volcano are volcanic-tectonic earthquakes. The low frequency seismic waveforms observed at a few stations may be caused by local mediums, and have no relation with long-period events. Although the level of seismicity increased obviously and earthquake swarms occurred more frequently than before, we considered that the magma activity is still in its early stage and the eruption risk of Changbaishan Tianchi volcano is still iow in the near future.

  2. The geology and petrology of Mauna Kea Volcano, Hawaii; a study of postshield volcanism

    Science.gov (United States)

    Wolfe, Edward W.; Wise, William S.; Dalrymple, G. Brent

    1997-01-01

    Mauna Kea Volcano, on the Island of Hawaii, is capped by lavas of alkalic and transitional basalt (Hamakua Volcanics) erupted between approximately 250-200 and 70-65 ka and hawaiite, mugearite, and benmoreite (Laupahoehoe Volcanics) erupted between approximately 65 and 4 ka. These lavas, which form the entire subaerial surface of the volcano, issued from numerous scattered vents and are intercalated on the upper slopes with glacial deposits. The lavas record diminishing magma-supply rate and degree of partial melting from the shield stage through the postshield stage. Much of the compositional variation apparently reflects fractionation of basaltic magma in reservoirs within and beneath the volcano.

  3. The anatomy of an andesite volcano: A time-stratigraphic study of andesite petrogenesis and crustal evolution at Ruapehu volcano, New Zealand

    DEFF Research Database (Denmark)

    Price, R.C.; Gamble, J.A.; Smith, I.E.M.;

    2012-01-01

    Ruapehu, New Zealand’s largest active andesite volcano is located at the southern tip of the Taupo Volcanic Zone (TVZ), the main locus of subduction-related volcanism in the North Island. Geophysical data indicate that crustal thickness transitions from ... Ruapehu. The volcano is built on a basement of Mesozoic metagreywacke and geophysical evidence together with xenoliths contained in lavas indicates that this is underlain by oceanic, meta-igneous lower crust. The present-day Ruapehu edifice has been constructed by a series of eruptive events that produced...

  4. 2015 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Dixon, James P.; Cameron, Cheryl E.; Iezzi, Alexandra M.; Wallace, Kristi

    2017-09-28

    The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 14 volcanic centers in Alaska during 2015. The most notable volcanic activity consisted of continuing intermittent ash eruptions from Cleveland and Shishaldin volcanoes in the Aleutian Islands. Two eruptive episodes, at Veniaminof and Pavlof, on the Alaska Peninsula ended in 2015. During 2015, AVO re-established the seismograph network at Aniakchak, installed six new broadband seismometers throughout the Aleutian Islands, and added a Multiple component Gas Analyzer System (MultiGAS) station on Augustine.

  5. 2012 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Herrick, Julie A.; Neal, Christina A.; Cameron, Cheryl E.; Dixon, James P.; McGimsey, Robert G.

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, or suspected unrest at 11 volcanic centers in Alaska during 2012. Of the two verified eruptions, one (Cleveland) was clearly magmatic and the other (Kanaga) was most likely a single phreatic explosion. Two other volcanoes had notable seismic swarms that probably were caused by magmatic intrusions (Iliamna and Little Sitkin). For each period of clear volcanic unrest, AVO staff increased monitoring vigilance as needed, reviewed eruptive histories of the volcanoes in question to help evaluate likely outcomes, and shared observations and interpretations with the public. 2012 also was the 100th anniversary of Alaska’s Katmai-Novarupta eruption of 1912, the largest eruption on Earth in the 20th century and one of the most important volcanic eruptions in modern times. AVO marked this occasion with several public events.

  6. Volcanic Stratigraphy and Potential Hazards of the Chihsingshan Volcano Subgroup in the Tatun Volcano Group, Northern Taiwan

    Directory of Open Access Journals (Sweden)

    Yu-Wei Tsai

    2010-01-01

    Full Text Available The Chihsingshan Volcano Subgroup (CVSG is one of the most important landforms located within the Tatun Volcano Group in northern Taiwan. Based on a Digital Terrain Model, contour maps and field investigations, the CVSG can be divided into four types of volcanic landforms: (1 a strato- or composite volcano, Chihsingshan; (2 domes, the Shamaoshan and a hidden unit; (3 lava cones, the Baiyunshan and the Hsiaotsaoshan; and (4 a scoria cone, the Chikushan. Meanwhile, many small craters are distributed linearly along two northeast trending normal-fault systems. The occurrences are predominantly lava flows with subsidiary fall deposits, pyroclastic flows, and lahars in which at least twenty layers of lava flow in the CVSG can be recognized. Among them, 16 layers in the Chihsingshan volcano, named as C1 - C16, two in the Baiyunshan, B1 - B2, and two in the Hsiaotsaoshan, H1 - H2. Our study suggests that the potential volcanic hazards include lava and pyroclastic flows and simultaneous or subsequent lahars, if the Chihsingshan erupts in a similar manner as in the past. A volcanic hazard zonation map can be constructed for the purpose of mitigation assuming the future eruptive center and eruptive volume.

  7. The Hawaiian Volcano Observatory: a natural laboratory for studying basaltic volcanism: Chapter 1 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Tilling, Robert I.; Kauahikaua, James P.; Brantley, Steven R.; Neal, Christina A.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    In the beginning of the 20th century, geologist Thomas A. Jaggar, Jr., argued that, to fully understand volcanic and associated hazards, the expeditionary mode of studying eruptions only after they occurred was inadequate. Instead, he fervently advocated the use of permanent observatories to record and measure volcanic phenomena—at and below the surface—before, during, and after eruptions to obtain the basic scientific information needed to protect people and property from volcanic hazards. With the crucial early help of American volcanologist Frank Alvord Perret and the Hawaiian business community, the Hawaiian Volcano Observatory (HVO) was established in 1912, and Jaggar’s vision became reality. From its inception, HVO’s mission has centered on several goals: (1) measuring and documenting the seismic, eruptive, and geodetic processes of active Hawaiian volcanoes (principally Kīlauea and Mauna Loa); (2) geological mapping and dating of deposits to reconstruct volcanic histories, understand island evolution, and determine eruptive frequencies and volcanic hazards; (3) systematically collecting eruptive products, including gases, for laboratory analysis; and (4) widely disseminating observatory-acquired data and analysis, reports, and hazard warnings to the global scientific community, emergency-management authorities, news media, and the public. The long-term focus on these goals by HVO scientists, in collaboration with investigators from many other organizations, continues to fulfill Jaggar’s career-long vision of reducing risks from volcanic and earthquake hazards across the globe.

  8. The use of digital outcrops to study monogenetic volcanoes: Case study at Croscat volcano (Garrotxa Volcanic Zone, Spain)

    Science.gov (United States)

    Geyer, Adelina; García-Sellés, David; Pedrazzi, Dario; Barde-Cabusson, Stéphanie; Martí, Joan; Muñoz, Josep Anton

    2014-05-01

    During the last years, it has been demonstrated that the study of outcrops with difficult or completely restricted access can be carried out by means of digital representations of the outcrop surface. Furthermore, the study of digital outcrops may facilitate visualization of the features of interest over the entire outcrop, as long as the digital outcrop can be analysed while navigating in real-time, with optional displays for perspective, scale distortions, and attribute filtering. In particular, Terrestrial Laser Scanning (TSL) instruments using Light Detection And Ranging technology (LIDAR) are capable of capturing topographic details and achieve modelling accuracy within a few centimetres. The data obtained permits the creation of detailed 3-D terrain models of larger coverage and accuracy than conventional methods and with almost complete safety of the operators. Here we show digital outcrops may be useful to perform the description of the internal structure of exposed volcanic edifices. A further advantageous application is the estimate of erosion rates and patterns that may be helpful in terms of hazard assessment or preservation of volcanic landscapes. We use as an example of application the Croscat volcano, a monogenetic edifice of the La Garrotxa volcanic field (Spain), which quarrying jobs have exposed the internal part of the volcano leading to a perfect view of its interior but making difficult the access to the upper parts. The Croscat volcano is additionally one of the most emblematic symbols of the La Garrotxa Volcanic Zone Natural Park being its preservation a main target of the park administration.

  9. Volcanic sulfur dioxide index and volcanic explosivity index inferred from eruptive volume of volcanoes in Jeju Island, Korea: application to volcanic hazard mitigation

    Science.gov (United States)

    Ko, Bokyun; Yun, Sung-Hyo

    2016-04-01

    Jeju Island located in the southwestern part of Korea Peninsula is a volcanic island composed of lavaflows, pyroclasts, and around 450 monogenetic volcanoes. The volcanic activity of the island commenced with phreatomagmatic eruptions under subaqueous condition ca. 1.8-2.0 Ma and lasted until ca. 1,000 year BP. For evaluating volcanic activity of the most recently erupted volcanoes with reported age, volcanic explosivity index (VEI) and volcanic sulfur dioxide index (VSI) of three volcanoes (Ilchulbong tuff cone, Songaksan tuff ring, and Biyangdo scoria cone) are inferred from their eruptive volumes. The quantity of eruptive materials such as tuff, lavaflow, scoria, and so on, is calculated using a model developed in Auckland Volcanic Field which has similar volcanic setting to the island. The eruptive volumes of them are 11,911,534 m3, 24,987,557 m3, and 9,652,025 m3, which correspond to VEI of 3, 3, and 2, respectively. According to the correlation between VEI and VSI, the average quantity of SO2 emission during an eruption with VEI of 3 is 2-8 × 103 kiloton considering that the island was formed under intraplate tectonic setting. Jeju Island was regarded as an extinct volcano, however, several studies have recently reported some volcanic eruption ages within 10,000 year BP owing to the development in age dating technique. Thus, the island is a dormant volcano potentially implying high probability to erupt again in the future. The volcanoes might have explosive eruptions (vulcanian to plinian) with the possibility that SO2 emitted by the eruption reaches stratosphere causing climate change due to backscattering incoming solar radiation, increase in cloud reflectivity, etc. Consequently, recommencement of volcanic eruption in the island is able to result in serious volcanic hazard and this study provides fundamental and important data for volcanic hazard mitigation of East Asia as well as the island. ACKNOWLEDGMENTS: This research was supported by a grant [MPSS

  10. Volcanic hazard map for Telica, Cerro Negro and El Hoyo volcanoes, Nicaragua

    Science.gov (United States)

    Asahina, T.; Navarro, M.; Strauch, W.

    2007-05-01

    A volcano hazard study was conducted for Telica, Cerro Negro and El Hoyo volcanoes, Nicaragua, based on geological and volcanological field investigations, air photo analyses, and numerical eruption simulation. These volcanoes are among the most active volcanoes of the country. This study was realized 2004-2006 through technical cooperation of Japan International Cooperation Agency (JICA) with INETER, upon the request of the Government of Nicaragua. The resulting volcanic hazard map on 1:50,000 scale displays the hazards of lava flow, pyroclastic flows, lahars, tephra fall, volcanic bombs for an area of 1,300 square kilometers. The map and corresponding GIS coverage was handed out to Central, Departmental and Municipal authorities for their use and is included in a National GIS on Georisks developed and maintained by INETER.

  11. Io volcanism seen by new horizons: a major eruption of the Tvashtar volcano.

    Science.gov (United States)

    Spencer, J R; Stern, S A; Cheng, A F; Weaver, H A; Reuter, D C; Retherford, K; Lunsford, A; Moore, J M; Abramov, O; Lopes, R M C; Perry, J E; Kamp, L; Showalter, M; Jessup, K L; Marchis, F; Schenk, P M; Dumas, C

    2007-10-12

    Jupiter's moon Io is known to host active volcanoes. In February and March 2007, the New Horizons spacecraft obtained a global snapshot of Io's volcanism. A 350-kilometer-high volcanic plume was seen to emanate from the Tvashtar volcano (62 degrees N, 122 degrees W), and its motion was observed. The plume's morphology and dynamics support nonballistic models of large Io plumes and also suggest that most visible plume particles condensed within the plume rather than being ejected from the source. In images taken in Jupiter eclipse, nonthermal visible-wavelength emission was seen from individual volcanoes near Io's sub-Jupiter and anti-Jupiter points. Near-infrared emission from the brightest volcanoes indicates minimum magma temperatures in the 1150- to 1335-kelvin range, consistent with basaltic composition.

  12. Volcanic Processes and Geology of Augustine Volcano, Alaska

    Science.gov (United States)

    Waitt, Richard B.; Beget, James E.

    2009-01-01

    Augustine Island (volcano) in lower Cook Inlet, Alaska, has erupted repeatedly in late-Holocene and historical times. Eruptions typically beget high-energy volcanic processes. Most notable are bouldery debris avalanches containing immense angular clasts shed from summit domes. Coarse deposits of these avalanches form much of Augustine's lower flanks. A new geologic map at 1:25,000 scale depicts these deposits, these processes. We correlate deposits by tephra layers calibrated by many radiocarbon dates. Augustine Volcano began erupting on the flank of a small island of Jurassic clastic-sedimentary rock before the late Wisconsin glaciation (late Pleistocene). The oldest known effusions ranged from olivine basalt explosively propelled by steam, to highly explosive magmatic eruptions of dacite or rhyodacite shed as pumice flows. Late Wisconsin piedmont glaciers issuing from the mountainous western mainland surrounded the island while dacitic eruptive debris swept down the south volcano flank. Evidence is scant for eruptions between the late Wisconsin and about 2,200 yr B.P. On a few south-flank inliers, thick stratigraphically low pumiceous pyroclastic-flow and fall deposits probably represent this period from which we have no radiocarbon dates on Augustine Island. Eruptions between about 5,350 and 2,200 yr B.P. we know with certainty by distal tephras. On Shuyak Island 100 km southeast of Augustine, two distal fall ashes of Augustinian chemical provenance (microprobe analysis of glass) date respectively between about 5,330 and 5,020 yr B.P. and between about 3,620 and 3,360 yr B.P. An Augustine ash along Kamishak Creek 70 km southwest of Augustine dates between about 3,850 and 3,660 yr B.P. A probably Augustinian ash lying within peat near Homer dates to about 2,275 yr B.P. From before 2,200 yr B.P. to the present, Augustine eruptive products abundantly mantle the island. During this period, numerous coarse debris avalanches swept beyond Augustine's coast, most

  13. Geochemical characterization of a Quaternary monogenetic volcano in Erciyes Volcanic Complex: Cora Maar (Central Anatolian Volcanic Province, Turkey)

    Science.gov (United States)

    Gencalioglu-Kuscu, Gonca

    2011-11-01

    Central Anatolian Volcanic Province (CAVP) is a fine example of Neogene-Quaternary post-collisional volcanism in the Alpine-Mediterranean region. Volcanism in the Alpine-Mediterranean region comprises tholeiitic, transitional, calc-alkaline, and shoshonitic types with an "orogenic" fingerprint. Following the orogenic volcanism, subordinate, within-plate alkali basalts ( sl) showing little or no orogenic signature are generally reported in the region. CAVP is mainly characterized by widespread calc-alkaline andesitic-dacitic volcanism with orogenic trace element signature, reflecting enrichment of their source regions by subduction-related fluids. Cora Maar (CM) located within the Erciyes pull-apart basin, is an example to numerous Quaternary monogenetic volcanoes of the CAVP, generally considered to be alkaline. Major and trace element geochemical and geochronological data for the CM are presented in comparison with other CAVP monogenetic volcanoes. CM scoria is basaltic andesitic, transitional-calc-alkaline in nature, and characterized by negative Nb-Ta, Ba, P and Ti anomalies in mantle-normalized patterns. Unlike the "alkaline" basalts of the Mediterranean region, other late-stage basalts from the CAVP monogenetic volcanoes are classified as tholeiitic, transitional and mildly alkaline. They display the same negative anomalies and incompatible element ratios as CM samples. In this respect, CM is comparable to other CAVP monogenetic basalts ( sl), but different from the Meditterranean intraplate alkali basalts. Several lines of evidence suggest derivation of CM and other CAVP monogenetic basalts from shallow depths within the lithospheric mantle, that is from a garnet-free source. In a wider regional context, CAVP basalts ( sl) are comparable to Apuseni (Romania) and Big Pine (Western Great Basin, USA) volcanics, except the former have depleted Ba contents. This is a common feature for the CAVP volcanics and might be related to crustal contamination or source

  14. 2009 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    McGimsey, Robert G.; Neal, Christina A.; Girina, Olga A.; Chibisova, Marina; Rybin, Alexander

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, and reports of unusual activity at or near eight separate volcanic centers in Alaska during 2009. The year was highlighted by the eruption of Redoubt Volcano, one of three active volcanoes on the western side of Cook Inlet and near south-central Alaska's population and commerce centers, which comprise about 62 percent of the State's population of 710,213 (2010 census). AVO staff also participated in hazard communication and monitoring of multiple eruptions at ten volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  15. Preventing volcanic catastrophe; the U.S. International Volcano Disaster Assistance Program

    Science.gov (United States)

    Ewert, J.W.; Murray, T.L.; Lockhart, A. B.; Miller, C.D.

    1993-01-01

    When the seismograph began to record the violent earth-shaking caused by yet another eruption of the Nevado del Ruiz volcano in Colombia, no one thought that a few hours later more than 23,000 people would be dead, killed by lahars (volcanic debris flows) in towns and villages several tens of kilometers away from the volcano. Before the fatal eruption the volcano was being monitored by scientists at a seismic station located 9 km from the summit, and information about the volcano's activity was being sent to Colombian emergency-response coordinators who were charged with alerting the public of the danger from the active volcano. Furthermore, area known to be in the pathways lahars had already been identified on maps and communities at risk had been told of their precarious locations.

  16. Volcanoes of México: An Interactive CD-ROM From the Smithsonian's Global Volcanism Program

    Science.gov (United States)

    Siebert, L.; Kimberly, P.; Calvin, C.; Luhr, J. F.; Kysar, G.

    2002-12-01

    The Smithsonian Institution's Global Volcanism Program is nearing completion of an interactive CD-ROM, the Volcanoes of México. This CD is the second in a series sponsored by the U.S. Department of Energy Office of Geothermal Technologies to collate Smithsonian data on Quaternary volcanism as a resource for the geothermal community. It also has utility for those concerned with volcanic hazard and risk mitgation as well as an educational tool for those interested in Mexican volcanism. We acknowledge the significant contributions of many Mexican volcanologists to the eruption reports, data, and images contained in this CD, in particular those contributions of the Centro Nacional de Prevencion de Desastres (CENAPRED), the Colima Volcano Observatory of the University of Colima, and the Universidad Nacional Autónoma de México (UNAM). The Volcanoes of México CD has a format similar to that of an earlier Smithsonian CD, the Volcanoes of Indonesia, but also shows Pleistocene volcanic centers and additional data on geothermal sites. A clickable map of México shows both Holocene and Pleistocene volcanic centers and provides access to individual pages on 67 volcanoes ranging from Cerro Prieto in Baja California to Tacaná on the Guatemalan border. These include geographic and geologic data on individual volcanoes (as well as a brief paragraph summarizing the geologic history) along with tabular eruption chronologies, eruptive characteristics, and eruptive volumes, when known. Volcano data are accessible from both geographical and alphabetical searches. A major component of the CD is more than 400 digitized images illustrating the morphology of volcanic centers and eruption processes and deposits, providing a dramatic visual primer to the country's volcanoes. Images of specific eruptions can be directly linked to from the eruption chronology tables. The Volcanoes of México CD includes monthly reports and associated figures and tables cataloging volcanic activity in M

  17. Effect of gas emissions from Tianchi volcano (NE China) on environment and its potential volcanic hazards

    Institute of Scientific and Technical Information of China (English)

    GUO; Zhengfu; LIU; Jiaqi; HAN; Jingtai; HE; Huaiyu; DAI; Guoliang; YOU; Haitao

    2006-01-01

    The Tianchi volcano in the Changbai Mountains is located on the boundary between China and North Korea. There are many times of eruptions of the Tianchi volcano during the Holocene. One of its large eruptions occurred around 1000 years ago dated by 14C method and historical records. Composition of products of the largest Tianchi volcanic eruption studied is characterized by comenditic Plinian fallout and unwelded ignimbrite, which are mainly distributed in China and North Korea. Caldera is about 4.4 km long and 3.4 km wide, which had filled with water (e.g. Tianchi Lake). The Tianchi volcanic cone is about 2700 m high above sea level. The Tianchi Lake is located on the summit of the volcanic cone, that is also highest peak of the Changbai Mountains in northeastern China. This study analyzed Cl, F, S and H2O concentrations of melt inclusions in the phenocryst minerals (anorthoclase and quartz) and co-existing matrix glasses using the electron microprobe and estimated environmental effect of Tianchi volcanic gases. The authors proposed a new method to evaluate future eruption of active volcano and estimate potential volcanic hazards based on contents of volatile emissions. Using this method, we made a perspective of future volcanic hazard in this region.

  18. Numerical simulation of tsunami generation by cold volcanic mass flows at Augustine Volcano, Alaska

    Science.gov (United States)

    Waythomas, C.F.; Watts, P.; Walder, J.S.

    2006-01-01

    Many of the world's active volcanoes are situated on or near coastlines. During eruptions, diverse geophysical mass flows, including pyroclastic flows, debris avalanches, and lahars, can deliver large volumes of unconsolidated debris to the ocean in a short period of time and thereby generate tsunamis. Deposits of both hot and cold volcanic mass flows produced by eruptions of Aleutian arc volcanoes are exposed at many locations along the coastlines of the Bering Sea, North Pacific Ocean, and Cook Inlet, indicating that the flows entered the sea and in some cases may have initiated tsunamis. We evaluate the process of tsunami generation by cold granular subaerial volcanic mass flows using examples from Augustine Volcano in southern Cook Inlet. Augustine Volcano is the most historically active volcano in the Cook Inlet region, and future eruptions, should they lead to debris-avalanche formation and tsunami generation, could be hazardous to some coastal areas. Geological investigations at Augustine Volcano suggest that as many as 12-14 debris avalanches have reached the sea in the last 2000 years, and a debris avalanche emplaced during an A.D. 1883 eruption may have initiated a tsunami that was observed about 80 km east of the volcano at the village of English Bay (Nanwalek) on the coast of the southern Kenai Peninsula. Numerical simulation of mass-flow motion, tsunami generation, propagation, and inundation for Augustine Volcano indicate only modest wave generation by volcanic mass flows and localized wave effects. However, for east-directed mass flows entering Cook Inlet, tsunamis are capable of reaching the more populated coastlines of the southwestern Kenai Peninsula, where maximum water amplitudes of several meters are possible.

  19. Volcanic spreading forcing and feedback in geothermal reservoir development, Amiata Volcano, Italia

    Science.gov (United States)

    Borgia, Andrea; Mazzoldi, Alberto; Brunori, Carlo Alberto; Allocca, Carmine; Delcroix, Carlo; Micheli, Luigi; Vercellino, Alberto; Grieco, Giovanni

    2014-09-01

    We made a stratigraphic, structural and morphologic study of the Amiata Volcano in Italy. We find that the edifice is dissected by intersecting grabens that accommodate the collapse of the higher sectors of the volcano. In turn, a number of compressive structures and diapirs exist around the margin of the volcano. These structures create an angular drainage pattern, with stream damming and captures, and a set of lakes within and around the volcano. We interpret these structures as the result of volcanic spreading of Amiata on its weak substratum, formed by the late Triassic evaporites (Burano Anhydrites) and the Middle-Jurassic to Early-Cretaceous clayey chaotic complexes (Ligurian Complex). Regional doming created a slope in the basement facilitating the outward flow and spreading of the ductile layers forced by the volcanic load. We model the dynamics of spreading with a scaled lubrication approximation of the Navier Stokes equations, and numerically study a set of solutions. In the model we include simple functions for volcanic deposition and surface erosion that change the topography over time. Scaling indicates that spreading at Amiata could still be active. The numerical solution shows that, as the central part of the edifice sinks into the weak basement, diapiric structures of the underlying formations form around the base of the volcano. Deposition of volcanic rocks within the volcano and surface erosion away from it both enhance spreading. In addition, a sloping basement may constitute a trigger for spreading and formation of trains of adjacent diapirs. As a feedback, the hot hydrothermal fluids decrease the shear strength of the anhydrites facilitating the spreading process. Finally, we observe that volcanic spreading has created ideal heat traps that constitute todays' exploited geothermal fields at Amiata. Normal faults generated by volcanic spreading, volcanic conduits, and direct contact between volcanic rocks (which host an extensive fresh

  20. Yanshan, Gaoshan-Two Active Volcanoes of the Volcanic Cluster in Arshan, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    Bai Zhida; Tian Mingzhong; Wu Fadong; Xu Debing; Li Tuanjie

    2005-01-01

    The volcanic cluster in Arshan, Inner Mongolia, is located in the west of the middle section of the Da Hinggan Mountains. There are more than forty Cenozoic volcanoes among which the Yanshan Volcano and Gaoshan Volcano are the active ones in broad sense and basaltic central vents. Arshan is a newly found volcanic active region in the Chinese continent. The volcanoes are perfectly preserved and composed of cinder cones, pyroclastic sheets and lava flows. Their cones are grand and the Gaoshan cone is about 362m high, and the depth of the Yanshan crater is about 140m. The pyroclastic sheet is mainly made up of scoria, and the distribution area of scoria with thickness more than 1m is about 27km2. There are two Carbonized-wood sites in the pyroclastic sheet and the 14C datings indicate ages of 1990 ± 100a B. P and 1900 ±70a B. P, which are rectified by dendrodating. Basaltic lava flows are uncovered, and they change from pahoehoe in the early stage to aa in the later stage. There are lots of perfect fumarolic cones, fumarolic dishes and lava tumulus in the front zones. The spread of lava flow is controlled by the local topography and its main body flowed northwestwards covering the Holocene rivers and swamp deposits and blocked up the Halahahe river and its branches to create six lava-dam lakes. For these distinguishing features, Arshan volcanic cluster could be called another natural "Volcano Museum".

  1. Infrasound Monitoring of the Volcanic Activities of Japanese Volcanoes in Korea

    Science.gov (United States)

    Lee, H. I.; Che, I. Y.; Shin, J. S.

    2015-12-01

    Since 1999 when our first infrasound array station(CHNAR) has been installed at Cheolwon, Korea Institute of Geoscience and Mineral Resources(KIGAM) is continuously observing infrasound signals with an infrasound array network, named KIN(Korean Infrasound Network). This network is comprised of eight seismo-acoustic array stations(BRDAR, YPDAR, KMPAR, CHNAR, YAGAR, KSGAR, ULDAR, TJIAR). The aperture size of the smallest array is 300m and the largest is about 1.4km. The number of infrasound sensors are between 4(TJIAR) and 18(YAGAR), and 1~5 seismometers are collocated with infrasound sensors. Many interesting infrasound signals associated with different type of sources, such as blasting, large earthquake, bolide, volcanic explosion are detected by KIN in the past 15 years. We have analyzed the infrasound signals possibly associated with the japanese volcanic explosions with reference to volcanic activity report published by Japanese Meteorological Agency. Analysis results of many events, for example, Asama volcano explosion in 2004 and Shinmoe volcano in 2011, are well matched with the official report. In some cases, however, corresponding infrasound signals are not identified. By comparison of the infrasound signals from different volcanoes, we also found that the characteristics of signals are distinguishing. It may imply that the specific volcano has its own unique fingerprint in terms of infrasound signal. It might be investigated by long-term infrasound monitoring for a specific volcano as a ground truth generating repetitive infrasound signal.

  2. Characterization of fine volcanic ash from explosive eruption from Sakurajima volcano, South Japan

    Science.gov (United States)

    Nanayama, F.; Furukawa, R.; Ishizuka, Y.; Yamamoto, T.; Geshi, N.; Oishi, M.

    2013-12-01

    Explosive volcanic eruptions can affect infrastructure and ecosystem by their dispersion of the volcanic particle. Characterization of volcanic particle expelled by explosive eruption is crucial for evaluating for quantitative hazard assessment by future volcanic eruption. Especially for fine volcanic ash less than 64 micron in diameter, it can disperse vast area from the source volcano and be easily remobilized by surface wind and precipitation after the deposition. As fine volcanic ash is not preserved well at the earth surface and in strata except for enormously large scale volcanic eruption. In order to quantify quantitative characteristics of fine volcanic ash particle, we sampled volcanic ash directly falling from the eruption cloud from Showa crater, the most active vent of Sakurajima volcano, just before landing on ground. We newly adopted high precision digital microscope and particle grain size analyzer to develop hazard evaluation method of fine volcanic ash particle. Field survey was performed 5 sequential days in January, 2013 to take tamper-proof volcanic ash samples directly obtained from the eruption cloud of the Sakurajima volcano using disposable paper dishes and plastic pails. Samples were taken twice a day with time-stamp in 40 localities from 2.5 km to 43 km distant from the volcano. Japan Meteorological Agency reported 16 explosive eruptions of vulcanian style occurred during our survey and we took 140 samples of volcanic ash. Grain size distribution of volcanic ash was measured by particle grain size analyzer (Mophologi G3S) detecting each grain with parameters of particle diameter (0.3 micron - 1 mm), perimeter, length, area, circularity, convexity, solidity, and intensity. Component of volcanic ash was analyzed by CCD optical microscope (VHX-2000) which can take high resolution optical image with magnifying power of 100-2500. We discriminated each volcanic ash particle by color, texture of surface, and internal structure. Grain size

  3. 2008 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Neal, Christina A.; McGimsey, Robert G.; Dixon, James P.; Cameron, Cheryl E.; Nuzhdaev, Anton A.; Chibisova, Marina

    2011-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest or suspected unrest at seven separate volcanic centers in Alaska during 2008. Significant explosive eruptions at Okmok and Kasatochi Volcanoes in July and August dominated Observatory operations in the summer and autumn. AVO maintained 24-hour staffing at the Anchorage facility from July 12 through August 28. Minor eruptive activity continued at Veniaminof and Cleveland Volcanoes. Observed volcanic unrest at Cook Inlet's Redoubt Volcano presaged a significant eruption in the spring of 2009. AVO staff also participated in hazard communication regarding eruptions or unrest at nine volcanoes in Russia as part of a collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  4. Volcanic rifts bracketing volcanoes: an analogue answer to an old unsolved problem

    Science.gov (United States)

    Mussetti, Giulio; van Wyk de Vries, Benjamin; Corti, Giacomo; Hagos, Miruts

    2015-04-01

    It has been observed in Central America that many volcanoes have volcanic alignments and faults at their east and west feet. A quick look at many rifts indicates that this also occurs elsewhere. While this feature has been noted for at least 30 years, no explanation has ever really been convincingly put forward. During analogue experiments on rifting volcanoes we have mixed the presence of a volcanic edifice with an underlying intrusive complex. The models use a rubber sheet that is extended and provides a broad area of extension (in contrast to many moving plate models that have one localised velocity discontinuity). This well suits the situation in many rifts and diffuse strike-slip zones (i.e. Central America and the East African Rift). We have noted the formation of localised extension bracketing the volcano, the location of which depends on the position of the analogue intrusion. Thus, we think we have found the answer to this long standing puzzle. We propose that diffuse extension of a volcano and intrusive complex generates two zones of faulting at the edge of the intrusion along the axis of greatest extensional strain. These serve to create surface faulting and preferential pathways for dykes. This positioning may also create craters aligned along the axis of extension, which is another notable feature of volcanoes in Central America. Paired volcanoes and volcanic uplifts in the Danakil region of Ethiopia may also be a consequence of such a process and lead us to draw some new preliminary cross sections of the Erta Ale volcanic range.

  5. Hazard map for volcanic ballistic impacts at El Chichón volcano (Mexico)

    Science.gov (United States)

    Alatorre-Ibarguengoitia, Miguel; Ramos-Hernández, Silvia; Jiménez-Aguilar, Julio

    2014-05-01

    The 1982 eruption of El Chichón Volcano in southeastern Mexico had a strong social and environmental impact. The eruption resulted in the worst volcanic disaster in the recorded history of Mexico, causing about 2,000 casualties, displacing thousands, and producing severe economic losses. Even when some villages were relocated after the 1982 eruption, many people still live and work in the vicinities of the volcano and may be affected in the case of a new eruption. The hazard map of El Chichón volcano (Macías et al., 2008) comprises pyroclastic flows, pyroclastic surges, lahars and ash fall but not ballistic projectiles, which represent an important threat to people, infrastructure and vegetation in the case of an eruption. In fact, the fatalities reported in the first stage of the 1982 eruption were caused by roof collapse induced by ashfall and lithic ballistic projectiles. In this study, a general methodology to delimit the hazard zones for volcanic ballistic projectiles during volcanic eruptions is applied to El Chichón volcano. Different scenarios are defined based on the past activity of the volcano and parameterized by considering the maximum kinetic energy associated with ballistic projectiles ejected during previous eruptions. A ballistic model is used to reconstruct the "launching" kinetic energy of the projectiles observed in the field. The maximum ranges expected for the ballistics in the different explosive scenarios defined for El Chichón volcano are presented in a ballistic hazard map which complements the published hazard map. These maps assist the responsible authorities to plan the definition and mitigation of restricted areas during volcanic crises.

  6. Global Volcano Model: progress towards an international co-ordinated network for volcanic hazard and risk

    Science.gov (United States)

    Loughlin, Susan

    2013-04-01

    GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. GVM is a network that aims to co-ordinate and integrate the efforts of the international volcanology community. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM. Activities currently include: design and development of databases of volcano data, volcanic hazards, vulnerability and exposure with internationally agreed metadata standards; establishment of methodologies for analysis of the data (e.g. hazard and exposure indices) to inform risk assessment; development of complementary hazards models and create relevant hazards and risk assessment tools. GVM acts through establishing task forces to deliver explicit deliverables in finite periods of time. GVM has a task force to deliver a global assessment of volcanic risk for UN ISDR, a task force for indices, and a task force for volcano deformation from satellite observations. GVM is organising a Volcano Best Practices workshop in 2013. A recent product of GVM is a global database on large magnitude explosive eruptions. There is ongoing work to develop databases on debris avalanches, lava dome hazards and ash hazard. GVM aims to develop the capability to anticipate future volcanism and its consequences.

  7. What is a Volcano? How planetary volcanism has changed our definition

    Science.gov (United States)

    Lopes, R. M.; Mitchell, K. L.; Williams, D. A.; Mitri, G.; Gregg, T. K.

    2009-12-01

    The discovery of numerous extra-terrestrial volcanoes, including active ones, has stretched our traditional definition of what is a volcano. We now know that the nature of volcanism is highly variable over the Solar System, and the traditional definition of a volcano as defined for Earth needs to be modified and expanded to include processes such as cryovolcanism, in which aqueous mixtures are erupted from the interior to the surface. Plate tectonics, which largely controls the location and types of volcanoes on Earth, has not been identified on any other planetary body. Volcanic and tectonic structures on other bodies may have different origins from their terrestrial morphological counterparts. For example, calderas on Io are associated with effusive rather than explosive eruptions. Lava lakes on Io may be more similar to the Earth’s East Pacific Rise eruptions that give rise to temporary lava lakes rather than to terrestrial lava lakes where there is a shallow magma chamber. Volcanic features on Io, and also Titan, appear to be randomly distributed on the surface and not associated with a global tectonic control or with the locations of mountains. Cryovolcanism on Titan, which may still be active, is likely made possible by bottom crevasses opening in the icy crust and formation of ammonia-water pockets in the ice shell. Large scale tectonic stress (tides, global volume changes and/or topography) may promote resurfacing. Mountains on Titan may be the result of long-term cooling of the interior causing global volume contraction (Mitri et al. 2009, JGR submitted). This paper will focus on active volcanic features on Io, cryovolcanism on Titan, and how these phenomena have led us to suggest the following definition that encompasses the different forms of volcanic activity seen in other worlds: A volcano is an opening on a planet or moon’s surface from which magma, as defined for that body, and/or magmatic gas is erupted.

  8. Peralkaline volcanism in a continental collisional setting: Mount Nemrut volcano, Eastern Anatolia

    Science.gov (United States)

    Çubukçu, H. E.; Ulusoy, I.; Aydar, E.; Sen, E.; Ersoy, O.; Gourgaud, A.

    2012-04-01

    Quaternary Mount Nemrut is an active volcano in the Eastern Anatolia which culminates at 2948 m and having an elliptic summit caldera with 8.5 x 7 km diameter. The volcano is situated on the east of the deformed and dissected remnant of the Muş-Van ramp basin located at the northern foot of the Bitlis-Zagros suture zone. The suture zone is the southern margin of the continental collision between Arabian and Anatolian plates. The continental collision along the Bitlis-Zagros suture zone commenced in the Middle Miocene following the closure of the southern segment of Neo-Tethys ocean and the subduction of northern margin of Arabian plate beneath Anatolian plate. Upon the collision and the uplift of the region, widespread volcanism, which exhibits varying eruption styles and geochemical characteristics, affected most of the Eastern Anatolia. The intracontinental convergence and N - S directed compressional - contractional tectonic regime remained till the end of Late Miocene. However, compressional - extensional regime became dominant in the Early-Late Pliocene. Following the slab break off, asthenosphere beneath the Arabian Foreland probably have migrated towards the slab window, which was opened during the detachment, and invaded the mantle wedge beneath East Anatolian Collision zone. Volcanism is still active in the region, represented by major Quaternary volcanic centers. The magmatic characteristics of Nemrut volcano is appealingly distinct compared to the other Quaternary volcanic centers in the region. The overall geochemical and mineralogical affinity of Nemrut volcanism exhibits strong similarities with the well-known sites of continental intra-plate extension. The volcano has distinguishing features of a typical silica oversaturated peralkaline (molecular ratio (Na + K / Al)>1) suite: (a) The volcanic products vary from transitional olivine basalt to peralkaline rhyolite (abundant comendite and scarce pantellerite) (b) Predominance by erupted volume of

  9. Faults and volcanoes: Main volcanic structures in the Acambay Graben, Mexico

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Pedrazzi, D.; Suñe-Puchol, I.; Lacan, P.

    2016-12-01

    The Mexican Volcanic Belt (MVB) province is best known by the major stratovolcanoes, such as Popocatepetl and Colima, but most of the province is formed by modest size stratovolcanoes and monogenetic cones. Regional fault systems were developed together with the building of the volcanic province; the most notorious one is Chapala-Tula Fault System (CTFS), which runs parallel to the central sector of the MVB, and thus it is also referred to as the Intra-Arc fault system. Acambay graben (AG) is part of this central system. It is a 20 x 70 km depression located 100 km to the NW of Mexico City, at the easternmost end of the E-W trending CTFS, and was formed as the result of NS to NE oriented extension. Seismically active normal faults, such as the Acambay-Tixmadejé fault, with a mB =7 earthquake in 1912, delimit the AG. The graben includes several volcanic structures and associated deposits ranging in age from Miocene to 3 ka. The main structures are two stratovolcanoes, Altamirano (900 m high) and Temascalcingo (800 m high). There are also several Miocene-Pliocene lava domes, and Quaternary small cinder cones and shield volcanoes. Faulting of the Acambay graben affects all these volcanic forms, but depending on their ages, the volcanoes are cut by several faults or by a few. That is the case of Altamirano and Temascalcingo volcanoes, where the former is almost unaffected whereas the latter is highly dissected by faults. Altamirano is younger than Temascalcingo; youngest pyroclastic deposits from Altamirano are dated at 12-3 ka, and those from Temascalcingo at 40-25 ka (radiocarbon ages). The relatively young ages found in volcanic deposits within the Acambay graben raise the volcanic danger level in this area, originally marked as an inactive volcanic zone, but activity could restart at any time. Supported by DGAPA-PAPIIT-UNAM grant IN-104615.

  10. DEM-based model for reconstructing volcano's morphology from primary volcanic landforms

    Science.gov (United States)

    Gayer, Eric; Lopez, Philippe; Michon, Laurent

    2014-05-01

    Volumes of magma intruded in and emitted by volcanoes through time can be estimated by reconstruction of volcano's morphology and time sequence. Classical approaches for quantifying magma volumes on active volcanoes are based on the difference between pre- and post-eruption digital elevation models (DEM), but this kind of approach needs the pre-eruptive surfaces to be available. For old and eroded volcanoes these surfaces are poorly constrained. However, because the geometrical form of many volcanic edifices exhibits a remarkable symmetry we propose, here, a new approach using primary volcanic landforms in order to estimate the amount of the both erupted and eroded material and to locate eruptive centers. A large fraction of composite volcanoes have near constant slope on their flanks and a form that is concave upwards near their summits. But many phenomena can lead to non-symetrical edifices and complex morphologies can result, for example from parasitic centers of volcanism on the flanks, from alternation of short effusive and explosive construction phases, from flank or caldera collapses, or from glacial and other types of erosion. In this study we propose that, on the first order approximation, complex morphologies can be modeled by piling regular cones. In this model, cones centers and slopes are derived by fitting primary volcanic landform with a linear function :elevation=f(distance from center). Such an approach allows to estimate both errors on location of the eruptive center and on the volume of the resulting cones. This model can then be used for quantifying volume of erupted and eroded material, and for quantifying catastrophic events as giant landslides or flank collapse. This approach is tested on four different active volcanoes : Mount Mayon (Philippines), Mount Fuji (Japan), Mount Etna (Sicily) and Mount Teide (Canary Island) to estimate errors in volume between modeled and actual edifices. It is then used on volcanoes of La Réunion hotspot to

  11. Field-trip guides to selected volcanoes and volcanic landscapes of the western United States

    Science.gov (United States)

    ,

    2017-06-23

    The North American Cordillera is home to a greater diversity of volcanic provinces than any comparably sized region in the world. The interplay between changing plate-margin interactions, tectonic complexity, intra-crustal magma differentiation, and mantle melting have resulted in a wealth of volcanic landscapes.  Field trips in this guide book collection (published as USGS Scientific Investigations Report 2017–5022) visit many of these landscapes, including (1) active subduction-related arc volcanoes in the Cascade Range; (2) flood basalts of the Columbia Plateau; (3) bimodal volcanism of the Snake River Plain-Yellowstone volcanic system; (4) some of the world’s largest known ignimbrites from southern Utah, central Colorado, and northern Nevada; (5) extension-related volcanism in the Rio Grande Rift and Basin and Range Province; and (6) the eastern Sierra Nevada featuring Long Valley Caldera and the iconic Bishop Tuff.  Some of the field trips focus on volcanic eruptive and emplacement processes, calling attention to the fact that the western United States provides opportunities to examine a wide range of volcanological phenomena at many scales.The 2017 Scientific Assembly of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) in Portland, Oregon, was the impetus to update field guides for many of the volcanoes in the Cascades Arc, as well as publish new guides for numerous volcanic provinces and features of the North American Cordillera. This collection of guidebooks summarizes decades of advances in understanding of magmatic and tectonic processes of volcanic western North America. These field guides are intended for future generations of scientists and the general public as introductions to these fascinating areas; the hope is that the general public will be enticed toward further exploration and that scientists will pursue further field-based research.

  12. Geotourism and volcanoes: health hazards facing tourists at volcanic and geothermal destinations.

    Science.gov (United States)

    Heggie, Travis W

    2009-09-01

    Volcano tourism and tourism to geothermal destinations is increasingly popular. If such endeavors are to be a sustainable sector of the tourism industry, tourists must be made aware of the potential health hazards facing them in volcanic environments. With the aim of creating awareness amongst the tourism industry and practitioners of travel medicine, this paper reviews the potential influences and effects of volcanic gases such as carbon dioxide (CO(2)), hydrogen sulfide (H(2)S), sulfur dioxide (SO(2)), and hydrogen chloride/hydrochloric acid (HCl). It also reviews the negative health impacts of tephra and ash, lava flows, landslides, and mudflows. Finally, future research striving to quantify the health risks facing volcano tourists is recommended.

  13. Update of map the volcanic hazard in the Ceboruco volcano, Nayarit, Mexico

    Science.gov (United States)

    Suarez-Plascencia, C.; Camarena-Garcia, M. A.; Nunez-Cornu, F. J.

    2012-12-01

    The Ceboruco Volcano (21° 7.688 N, 104° 30.773 W) is located in the northwestern part of the Tepic-Zacoalco graben. Its volcanic activity can be divided in four eruptive cycles differentiated by their VEI and chemical variations as well. As a result of andesitic effusive activity, the "paleo-Ceboruco" edifice was constructed during the first cycle. The end of this cycle is defined by a plinian eruption (VEI between 3 and 4) which occurred some 1020 years ago and formed the external caldera. During the second cycle an andesitic dome built up in the interior of the caldera. The dome collapsed and formed the internal caldera. The third cycle is represented by andesitic lava flows which partially cover the northern and south-southwestern part of the edifice. The last cycle is represented by the andesitic lava flows of the nineteenth century located in the southwestern flank of the volcano. Actually, moderate fumarolic activity occurs in the upper part of the volcano showing temperatures ranging between 20° and 120°C. Some volcanic high frequency tremors have also been registered near the edifice. Shows the updating of the volcanic hazard maps published in 1998, where we identify with SPOT satellite imagery and Google Earth, change in the land use on the slope of volcano, the expansion of the agricultural frontier on the east sides of the Ceboruco volcano. The population inhabiting the area is 70,224 people in 2010, concentrated in 107 localities and growing at an annual rate of 0.37%, also the region that has shown an increased in the vulnerability for the development of economic activities, supported by highway, high road, railroad, and the construction of new highway to Puerto Vallarta, which is built in the southeast sector of the volcano and electrical infrastructure that connect the Cajon and Yesca Dams to Guadalajara city. The most important economic activity in the area is agriculture, with crops of sugar cane (Saccharum officinarum), corn, and jamaica

  14. Characteristics and management of the 2006-2008 volcanic crisis at the Ubinas volcano (Peru)

    Science.gov (United States)

    Rivera, Marco; Thouret, Jean-Claude; Mariño, Jersy; Berolatti, Rossemary; Fuentes, José

    2010-12-01

    Ubinas volcano is located 75 km East of Arequipa and ca. 5000 people are living within 12 km from the summit. This composite cone is considered the most active volcano in southern Peru owing to its 24 low to moderate magnitude (VEI 1-3) eruptions in the past 500 years. The onset of the most recent eruptive episode occurred on 27 March 2006, following 8 months of heightened fumarolic activity. Vulcanian explosions occurred between 14 April 2006 and September 2007, at a time ejecting blocks up to 40 cm in diameter to distances of 2 km. Ash columns commonly rose to 3.5 km above the caldera rim and dispersed fine ash and aerosols to distances of 80 km between April 2006 and April 2007. Until April 2007, the total volume of ash was estimated at 0.004 km 3, suggesting that the volume of fresh magma was small. Ash fallout has affected residents, livestock, water supplies, and crop cultivation within an area of ca. 100 km 2 around the volcano. Continuous degassing and intermittent mild vulcanian explosions lasted until the end of 2008. Shortly after the initial explosions on mid April 2006 that spread ash fallout within 7 km of the volcano, an integrated Scientific Committee including three Peruvian institutes affiliated to the Regional Committee of Civil Defense for Moquegua, aided by members of the international cooperation, worked together to: i) elaborate and publish volcanic hazard maps; ii) inform and educate the population; and iii) advise regional authorities in regard to the management of the volcanic crisis and the preparation of contingency plans. Although the 2006-2008 volcanic crisis has been moderate, its management has been a difficult task even though less than 5000 people now live around the Ubinas volcano. However, the successful management has provided experience and skills to the scientific community. This volcanic crisis was not the first one that Peru has experienced but the 2006-2008 experience is the first long-lasting crisis that the Peruvian civil

  15. Volcanic activity in the Acambay Graben: a < 25 Ka subplinian eruption from the Temascalcingo volcano and implications for volcanic hazard.

    Science.gov (United States)

    Pedrazzi, Dario; Aguirre Díaz, Gerardo; Sunyé Puchol, Ivan; Bartolini, Stefania; Geyer, Adelina

    2016-04-01

    The Trans-Mexican Volcanic Belt (TMVB) contains a large number of stratovolcanoes, some well-known, as Popocatepetl, Iztaccihuatl, Nevado de Toluca, or Colima and many others of more modest dimensions that are not well known but constitute the majority in the TMVB. Such volcanoes are, for example, Tequila, San Juan, Sangangüey, Cerro Culiacán, Cerro Grande, El Zamorano, La Joya, Palo Huerfano, Jocotitlán, Altamirano and Temascalcingo, among many others. The Temascalcingo volcano (TV) is an andesitic-dacitic stratovolcano located in the Trans-Mexican Volcanic Belt (TMVB) at the eastern part of the Acambay Graben (northwest portion of Estado de México). The TV is composed mainly by dacitic, porphyritic lavas, block and ash deposits and subordinate pumice fall deposits and ignimbrites (Roldán-Quintana et al., 2011). The volcanic structure includes a summit caldera that has a rectangular shape, 2.5×3.5 km, with the largest side oriented E-W, parallel to major normal faults affecting the edifice. The San Mateo Pumice eruption is one of the greatest paroxysmal episodes of this volcano with pumice deposits mainly exposed at the scarp of the Acambay-Tixmadeje fault and at the northern and northeastern flanks of TV. It overlies a paleosol dated at 25 Ka. A NE-trending dispersion was obtained from field data covering an area of at least 80 km2. These deposits overlie older lava flows and mud flows and are discontinuously covered and eroded by younger reworked deposits of Temascalcingo volcano. This event represents a highly explosive phase that generated a relatively thick and widespread pumice fallout deposit that may occur again in future eruptions. A similar eruption today would have a significantly impact in the region, overall due to the fact that there has been no systematic assessment of the volcanic hazard in any of the studies that have been conducted so far in the area. So, this is a pending and urgent subject that must be tackled without delay. Financed by

  16. Geochemistry and petrology of the most recent deposits from Cotopaxi volcano, Northern Volcanic Zone, Ecuador.

    OpenAIRE

    2011-01-01

    Cotopaxi volcano is located in the Northern Volcanic Zone of the South American Andes. Pyroclastic deposits and lava flows from Cotopaxi comprise basaltic andesites, andesites and rhyolites that have erupted since 13 200 years BP. Nine rhyolite eruptions were produced in at least five separate events, punctuated by intermittent andesite eruptions. High La/Yb (>5) and 230Th excesses in the andesites are consistent with equilibration of magma with garnet-bearing lower crust or mantle, and numer...

  17. Hazard map for volcanic ballistic impacts at Popocatépetl volcano (Mexico)

    Science.gov (United States)

    Alatorre-Ibargüengoitia, Miguel A.; Delgado-Granados, Hugo; Dingwell, Donald B.

    2012-11-01

    During volcanic explosions, volcanic ballistic projectiles (VBP) are frequently ejected. These projectiles represent a threat to people, infrastructure, vegetation, and aircraft due to their high temperatures and impact velocities. In order to protect people adequately, it is necessary to delimit the projectiles' maximum range within well-defined explosion scenarios likely to occur in a particular volcano. In this study, a general methodology to delimit the hazard zones for VBP during volcanic eruptions is applied to Popocatépetl volcano. Three explosion scenarios with different intensities have been defined based on the past activity of the volcano and parameterized by considering the maximum kinetic energy associated with VBP ejected during previous eruptions. A ballistic model is used to reconstruct the "launching" kinetic energy of VBP observed in the field. In the case of Vulcanian eruptions, the most common type of activity at Popocatépetl, the ballistic model was used in concert with an eruptive model to correlate ballistic range with initial pressure and gas content, parameters that can be estimated by monitoring techniques. The results are validated with field data and video observations of different Vulcanian eruptions at Popocatépetl. For each scenario, the ballistic model is used to calculate the maximum range of VBP under optimum "launching" conditions: ballistic diameter, ejection angle, topography, and wind velocity. Our results are presented in the form of a VBP hazard map with topographic profiles that depict the likely maximum ranges of VBP under explosion scenarios defined specifically for Popocatépetl volcano. The hazard zones shown on the map allow the responsible authorities to plan the definition and mitigation of restricted areas during volcanic crises.

  18. One hundred volatile years of volcanic gas studies at the Hawaiian Volcano Observatory: Chapter 7 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Sutton, A.J.; Elias, Tamar; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    The first volcanic gas studies in Hawai‘i, beginning in 1912, established that volatile emissions from Kīlauea Volcano contained mostly water vapor, in addition to carbon dioxide and sulfur dioxide. This straightforward discovery overturned a popular volatile theory of the day and, in the same action, helped affirm Thomas A. Jaggar, Jr.’s, vision of the Hawaiian Volcano Observatory (HVO) as a preeminent place to study volcanic processes. Decades later, the environmental movement produced a watershed of quantitative analytical tools that, after being tested at Kīlauea, became part of the regular monitoring effort at HVO. The resulting volatile emission and fumarole chemistry datasets are some of the most extensive on the planet. These data indicate that magma from the mantle enters the shallow magmatic system of Kīlauea sufficiently oversaturated in CO2 to produce turbulent flow. Passive degassing at Kīlauea’s summit that occurred from 1983 through 2007 yielded CO2-depleted, but SO2- and H2O-rich, rift eruptive gases. Beginning with the 2008 summit eruption, magma reaching the East Rift Zone eruption site became depleted of much of its volatile content at the summit eruptive vent before transport to Pu‘u ‘Ō‘ō. The volatile emissions of Hawaiian volcanoes are halogen-poor, relative to those of other basaltic systems. Information gained regarding intrinsic gas solubilities at Kīlauea and Mauna Loa, as well as the pressure-controlled nature of gas release, have provided useful tools for tracking eruptive activity. Regular CO2-emission-rate measurements at Kīlauea’s summit, together with surface-deformation and other data, detected an increase in deep magma supply more than a year before a corresponding surge in effusive activity. Correspondingly, HVO routinely uses SO2 emissions to study shallow eruptive processes and effusion rates. HVO gas studies and Kīlauea’s long-running East Rift Zone eruption also demonstrate that volatile emissions can

  19. Submarine volcanoes of the Kolumbo volcanic zone NE of Santorini Caldera, Greece

    Science.gov (United States)

    Nomikou, P.; Carey, S.; Papanikolaou, D.; Croff Bell, K.; Sakellariou, D.; Alexandri, M.; Bejelou, K.

    2012-06-01

    The seafloor northeast of Santorini volcano in Greece consists of a small, elongated rifted basin that has been the site of recent submarine volcanism. This area lies within the Cyclades back-arc region of the present Hellenic subduction zone where the seafloor of the eastern Mediterranean Sea is descending beneath the Aegean microplate. The Cycladic region and the Aegean Sea as a whole are known to be regions of north-south back-arc extension and thinning of continental crust. Nineteen submarine volcanic cones occur within this small rift zone, the largest of these being Kolumbo which last erupted explosively in 1650 AD, causing significant damage and fatalities on the nearby island of Santorini. Previous SEABEAM mapping and seismic studies from HCMR indicate that many of the smaller v'olcanic cones have been built above the present seafloor, while others are partly buried, indicating a range of ages for the activity along this volcanic line. None of the cones to the northeast of Kolumbo had been explored in detail prior to a cruise of the E/V Nautilus (NA007) in August 2010. The ROV Hercules was used to explore the slopes, summits and craters of 17 of the 19 centers identified on multibeam maps of the area. Water depths of the submarine volcano's summits ranged from 18 to 450 m. In general, the domes/craters northeast of Kolumbo were sediment covered and showed little evidence of recent volcanic activity. Outcrops of volcanic rock were found in the crater walls and slopes of some of the cones but they typically consisted of volcanic fragments of pumice and lava that have been cemented together by biological activity, indicative of the lack of recent eruptions. Geochemical analysis of samples collected on the northeast cones showed evidence of low temperature hydrothermal circulation on the summit and upper flanks in the form of stream-like manganese precipitates emanating from pits and fractures.

  20. International Collaboration on Building Local Technical Capacities for Monitoring Volcanic Activity at Pacaya Volcano, Guatemala.

    Science.gov (United States)

    Escobar-Wolf, R. P.; Chigna, G.; Morales, H.; Waite, G. P.; Oommen, T.; Lechner, H. N.

    2015-12-01

    Pacaya volcano is a frequently active and potentially dangerous volcano situated in the Guatemalan volcanic arc. It is also a National Park and a major touristic attraction, constituting an important economic resource for local municipality and the nearby communities. Recent eruptions have caused fatalities and extensive damage to nearby communities, highlighting the need for risk management and loss reduction from the volcanic activity. Volcanic monitoring at Pacaya is done by the Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH), instrumentally through one short period seismic station, and visually by the Parque Nacional Volcan de Pacaya y Laguna de Calderas (PNVPLC) personnel. We carry out a project to increase the local technical capacities for monitoring volcanic activity at Pacaya. Funding for the project comes from the Society of Exploration Geophysicists through the Geoscientists Without Borders program. Three seismic and continuous GPS stations will be installed at locations within 5 km from the main vent at Pacaya, and one webcam will aid in the visual monitoring tasks. Local educational and outreach components of the project include technical workshops on data monitoring use, and short thesis projects with the San Carlos University in Guatemala. A small permanent exhibit at the PNVPLC museum or visitor center, focusing on the volcano's history, hazards and resources, will also be established as part of the project. The strategy to involve a diverse group of local collaborators in Guatemala aims to increase the chances for long term sustainability of the project, and relies not only on transferring technology but also the "know-how" to make that technology useful. Although not a primary research project, it builds on a relationship of years of joint research projects at Pacaya between the participants, and could be a model of how to increase the broader impacts of such long term collaboration partnerships.

  1. On the origin of Mount Etna eruptive cycles and Stromboli volcano paroxysms: implications for an alternative mechanism of volcanic eruption

    CERN Document Server

    Nechayev, Andrei

    2014-01-01

    New mechanism of imbalance between magma column and fluid volume, accumulated in the magmatic system, is considered as a driving force of the volcanic eruption. Conditions of eruption based on this mechanism are used to explain main features of the volcanic activity (eruptive cycles and paroxysms) of the volcanoes Etna and Stromboli (Italy).

  2. Volcano-tectonics of the Al Haruj Volcanic Province, Central Libya

    Science.gov (United States)

    Elshaafi, Abdelsalam; Gudmundsson, Agust

    2016-10-01

    The Al Haruj intra-continental Volcanic Province (AHVP), located at the south-western margin of the Sirt Basin, hosts the most extensive and recent volcanic activity in Libya - which is considered typical for plate interiors. From north to south the AHVP is divided into two subprovinces, namely Al Haruj al Aswad and Al Haruj al Abiyad. The total area of the AHVP is around 42,000 km2. Despite the great size of the AHVP, its volcano-tectonic evolution and activity have received very little attention and are poorly documented and understood. Here we present new field data, and analytical and numerical results, on the volcano-tectonics of the AHVP. The length/thickness ratio of 47 dykes and volcanic fissures were measured to estimate magmatic overpressure at the time of eruption. The average dyke (length/thickness) ratio of 421 indicates magmatic overpressures during the associate fissure eruptions of 8-19 MPa (depending on host-rock elastic properties). Spatial distributions of 432 monogenetic eruptions sites/points (lava shields, pyroclastic cones) in the AHVP reveal two main clusters, one in the south and another in the north. Aligned eruptive vents show the dominating strike of volcanic fissures/feeder-dykes as WNW-ESE to NW-SE, coinciding with the orientation of one of main fracture/fault zones. Numerical modelling and field observations suggest that some feeder-dykes may have used steeply dipping normal-fault zones as part of their paths to the surface.

  3. GIS-Based emergency and evacuation planning for volcanic hazards in New Zealand

    DEFF Research Database (Denmark)

    Cole, J. W.; Sabel, C. E.; Blumenthal, E.

    2005-01-01

    in New Zealand is high, with 10 volcanoes or volcanic centres (Auckland, Bay of Islands, Haroharo, Mayor Island, Ruapehu, Taranaki, Tarawera, Taupo, Tongariro (including Ngauruhoe) and White Island) recognised as active or potentially active. In addition there are many active and potentially active...... (reduction, readiness, response and recovery) can benefit from CIS, including applications related to transportation systems, a critical element in managing effective lifelines in an emergency. This is particularly true immediately before and during a volcanic eruption. The potential for volcanic activity...... volcanoes along the Kermadec Island chain. There is a great deal of background information on all of these volcanoes, and GIS is currently being used for some aspects of monitoring (e.g. ERS and Envisat radar interferometry for observing deformation prior to eruptions). If an eruption is considered imminent...

  4. Separation of scattering and intrinsic attenuation at Asama volcano (Japan): Evidence of high volcanic structural contrasts

    Science.gov (United States)

    Prudencio, Janire; Aoki, Yosuke; Takeo, Minoru; Ibáñez, Jesús M.; Del Pezzo, Edoardo; Song, WenZhan

    2017-03-01

    In this study we show 2D intrinsic- and scattering-Q images of Asama volcano obtained by analyzing 2320 waveforms from active data. Observed energy envelopes were fitted to the diffusion model and separate intrinsic- and scattering-Q images were produced using a back-projection method based on a Gaussian-type weighting function. Synthetic tests indicate robustness and reliability of the results. Areas of high scattering attenuation coincide with the volcanic edifice and the summit at which recent eruptions took place. The intrinsic dissipation pattern shows a strong contrast between the east and west side of the volcanic structure with the low values observed in the west interpreted as solidified magma bodies. Our results demonstrate a strong relationship between structural heterogeneities and attenuation processes in volcanic areas and confirm the effectiveness of the present technique, which can be used as an imaging tool complementary to conventional techniques.

  5. Planetary Aspects of Volcanism: Insights Into the Volcano - Tectonic Relationship on Earth

    Science.gov (United States)

    Cañón-Tapia, E.

    2009-12-01

    There are many alternative definitions of a volcanic system, each focusing on different aspects of volcanic and/or magmatic activity. Although all of these definitions contribute to increase our understanding of volcanic phenomena, each was conceived with a specific aspect of volcanism in mind, therefore reducing its utility when problems beyond its own limits are considered, and perhaps more importantly, introducing subtle biases in the form in which we approach the study of this type of phenomena. In particular, the volcano-tectonic relationship most commonly used in volcanology textbooks seems to be biased towards volcanic activity on Earth, disregarding the presence of this type of phenomena in other planets, moons and even asteroids of our solar system. As a cursory examination of volcanism in the solar system reveals, the causes of volcanic activity deserve to be examined independently of any tectonic influence. Any model of volcanism of this type, however, needs to be flexible enough to accommodate tectonic variables if so required. In this work, such a flexible model of volcanism is outlined. This model is constructed by first exploring the form in which the Tectonic and the Volcanic systems are related to each other in different planets by using a mechanical analogy. Second, the analogy is used to identify key components of the volcanic system that need to be quantified first, therefore leading to the introduction of fundamental physical principles in the conceptual model of volcanism that is independent of the tectonic scenario. Third, the predictive capabilities of this model are compared to specific cases on Earth where the type of required information has been gathered previously. The results suggest that the physical constraints of the model are reasonable, therefore paving the road for further studies aiming to identify the tectonic contribution of volcanism on a case by case basis. Two corollaries of this study are that we need to learn to formulate

  6. Tectonic versus volcanic origin of the summit depression at Medicine Lake Volcano, California

    Energy Technology Data Exchange (ETDEWEB)

    Mark Leon Gwynn

    2010-05-01

    Medicine Lake Volcano is a Quaternary shield volcano located in a tectonically complex and active zone at the transition between the Basin and Range Province and the Cascade Range of the Pacific Province. The volcano is topped by a 7x12 km elliptical depression surrounded by a discontinuous constructional ring of basaltic to rhyolitic lava flows. This thesis explores the possibility that the depression may have formed due to regional extension (rift basin) or dextral shear (pull-apart basin) rather than through caldera collapse and examines the relationship between regional tectonics and localized volcanism. Existing data consisting of temperature and magnetotelluric surveys, alteration mineral studies, and core logging were compiled and supplemented with additional core logging, field observations, and fault striae studies in paleomagnetically oriented core samples. These results were then synthesized with regional fault data from existing maps and databases. Faulting patterns near the caldera, extension directions derived from fault striae P and T axes, and three-dimensional temperature and alteration mineral models are consistent with slip across arcuate ring faults related to magma chamber deflation during flank eruptions and/or a pyroclastic eruption at about 180 ka. These results are not consistent with a rift or pull-apart basin. Limited subsidence can be attributed to the relatively small volume of ash-flow tuff released by the only known major pyroclastic eruption and is inconsistent with the observed topographic relief. The additional relief can be explained by constructional volcanism. Striae from unoriented and oriented core, augmented by striae measurements in outcrop suggest that Walker Lane dextral shear, which can be reasonably projected from the southeast, has probably propagated into the Medicine Lake area. Most volcanic vents across Medicine Lake Volcano strike north-south, suggesting they are controlled by crustal weakness related to Basin and

  7. TECTONIC VERSUS VOLCANIC ORIGIN OF THE SUMMIT DEPRESSION AT MEDICINE LAKE VOLCANO, CALIFORNIA

    Energy Technology Data Exchange (ETDEWEB)

    Mark Leon Gwynn

    2010-05-01

    Medicine Lake Volcano is a Quaternary shield volcano located in a tectonically complex and active zone at the transition between the Basin and Range Province and the Cascade Range of the Pacific Province. The volcano is topped by a 7x12 km elliptical depression surrounded by a discontinuous constructional ring of basaltic to rhyolitic lava flows. This thesis explores the possibility that the depression may have formed due to regional extension (rift basin) or dextral shear (pull-apart basin) rather than through caldera collapse and examines the relationship between regional tectonics and localized volcanism. Existing data consisting of temperature and magnetotelluric surveys, alteration mineral studies, and core logging were compiled and supplemented with additional core logging, field observations, and fault striae studies in paleomagnetically oriented core samples. These results were then synthesized with regional fault data from existing maps and databases. Faulting patterns near the caldera, extension directions derived from fault striae P and T axes, and three-dimensional temperature and alteration mineral models are consistent with slip across arcuate ring faults related to magma chamber deflation during flank eruptions and/or a pyroclastic eruption at about 180 ka. These results are not consistent with a rift or pull-apart basin. Limited subsidence can be attributed to the relatively small volume of ash-flow tuff released by the only known major pyroclastic eruption and is inconsistent with the observed topographic relief. The additional relief can be explained by constructional volcanism. Striae from unoriented and oriented core, augmented by striae measurements in outcrop suggest that Walker Lane dextral shear, which can be reasonably projected from the southeast, has probably propagated into the Medicine Lake area. Most volcanic vents across Medicine Lake Volcano strike north-south, suggesting they are controlled by crustal weakness related to Basin and

  8. Preliminary volcano-hazard assessment for the Katmai volcanic cluster, Alaska

    Science.gov (United States)

    Fierstein, Judy; Hildreth, Wes

    2000-01-01

    The world’s largest volcanic eruption of the 20th century broke out at Novarupta (fig. 1) in June 1912, filling with hot ash what came to be called the Valley of Ten Thousand Smokes and spreading downwind more fallout than all other historical Alaskan eruptions combined. Although almost all the magma vented at Novarupta, most of it had been stored beneath Mount Katmai 10 km away, which collapsed during the eruption. Airborne ash from the 3-day event blanketed all of southern Alaska, and its gritty fallout was reported as far away as Dawson, Ketchikan, and Puget Sound (fig. 21). Volcanic dust and sulfurous aerosol were detected within days over Wisconsin and Virginia; within 2 weeks over California, Europe, and North Africa; and in latter-day ice cores recently drilled on the Greenland ice cap. There were no aircraft in Alaska in 1912—fortunately! Corrosive acid aerosols damage aircraft, and ingestion of volcanic ash can cause abrupt jet-engine failure. Today, more than 200 flights a day transport 20,000 people and a fortune in cargo within range of dozens of restless volcanoes in the North Pacific. Air routes from the Far East to Europe and North America pass over and near Alaska, many flights refueling in Anchorage. Had this been so in 1912, every airport from Dillingham to Dawson and from Fairbanks to Seattle would have been enveloped in ash, leaving pilots no safe option but to turn back or find refuge at an Aleutian airstrip west of the ash cloud. Downwind dust and aerosol could have disrupted air traffic anywhere within a broad swath across Canada and the Midwest, perhaps even to the Atlantic coast. The great eruption of 1912 focused scientific attention on Novarupta, and subsequent research there has taught us much about the processes and hazards associated with such large explosive events (Fierstein and Hildreth, 1992). Moreover, work in the last decade has identified no fewer than 20 discrete volcanic vents within 15 km of Novarupta (Hildreth and others

  9. Linear volcanic segments in the Sunda Arc, Indonesia: Implications for arc lithosphere control upon volcano distribution

    Science.gov (United States)

    Macpherson, C. G.; Pacey, A.; McCaffrey, K. J.

    2012-12-01

    The overall curvature of many subduction zones is immediately apparent and the term island arc betrays the common assumption that subduction zone magmatism occurs in curved zones. This assumption can be expressed by approximating island arcs as segments of small circles on the surface of a sphere. Such treatments predict that the location of arc volcanoes is related to their vertical separation from the slab (in fact, the depth to seismicity in the slab) and require that the primary control on the locus of magmatism lies either within the subducted slab or the mantle wedge that separates the subducted and overriding lithospheric plates. The concept of curved arcs ignores longstanding observations that magmatism in many subduction systems occurs as segments of linearly arranged volcanic centres. Further evidence for this distribution comes from the close relationship between magmatism and large scale, arc-parallel fabrics in some arcs. Similarly, exposures of deep arc crust or mantle often reveal elongation of magmatic intrusions sub-parallel to the inferred trend of the arc. The Sunda Arc forms the Indonesian islands from Sumatra to Alor and provides an important test for models of volcano distribution for several reasons. First, Sunda has hosted abundant historic volcanic activity. Second, with the notable exception of Krakatau, every volcano in the arc is subaerial from base to cone and, therefore, can be readily identified where there is a suitable extent of local mapping that can be used to ground-truth satellite imagery. Third, there are significant changes in the stress regime along the length of the arc, allowing the influence of the upper plate to be evaluated by comparison of different arc segments. Finally, much of the Sunda Arc has proved difficult to accommodate in models that try to relate volcano distribution to the depth to the subducted slab. We apply an objective line-fitting protocol; the Hough Transform, to explore the distribution of volcanoes

  10. Continuous measurements of volcanic gases from Popocatepetl volcano by thermal emission spectroscopy

    Science.gov (United States)

    Taquet, Noemie; Stremme, Wolfgang; Meza, Israel; Grutter, Michel

    2016-04-01

    Passive volcanic gas emissions have been poorly studied despite their impact on the atmospheric chemistry with important consequences on its geochemical cycles and climate change on regional and global scale. Therefore, long-term monitoring of volcanic gas plumes and their composition are of prime importance for climatic models and the estimation of the volcanic contribution to climate change. We present a new measurement and analysis strategy based on remote thermal emission spectroscopy which can provide continuous (day and night) information of the composition of the volcanic plume. In this study we show results from the Popocatepetl volcano in Mexico with measurements performed during the year 2015 from the Altzomoni Atmospheric Observatory (19.12N, -98.65W, 3,985 masl). This site, which forms part of the RUOA (www.ruoa.unam.mx) and NDACC (https://www2.acom.ucar.edu/irwg) networks, is located north of the crater of this active volcano at 12 km distance. Emission spectra were recorded with an FTIR spectrometer (OPAG22, Bruker) at 0.5 cm-1 spectral resolution and processed using the SFIT4 radiative transfer and profile retrieval code, based on the Optimal Estimation method (Rodgers, 1976; 1990; 2000). This newly improved methodology is intercompared to a former retrieval strategy using measurements from 2008 and recent results of the variability of the SiF4/SO2 composition ratio during 2015 is presented. A discussion of how the new measurements improve the understating of the impact of volcanic gas emissions on the atmosphere on global and regional scale is included.

  11. Probabilistic hazard analysis of Citlaltépetl (Pico de Orizaba) Volcano, eastern Mexican Volcanic Belt

    Science.gov (United States)

    De la Cruz-Reyna, Servando; Carrasco-Núñez, Gerardo

    2002-03-01

    Citlaltépetl or Pico de Orizaba is the highest active volcano in the North American continent. Although Citlaltépetl is at present in repose, its eruptive history reveals repetitive explosive eruptions in the past. Its relatively low eruption rate has favored significant population growth in areas that may be affected by a potential eruptive activity. The need of some criteria for hazards assessment and land-use planning has motivated the use of statistical methods to estimate the time and space distribution of volcanic hazards around this volcano. The analysis of past activity, from late Pleistocene to historic times, and the extent of some well-identified deposits are used to calculate the recurrence probabilities of eruptions of various size during time periods useful for land-use planning.

  12. UNCOVERING BURIED VOLCANOES: NEW DATA FOR PROBABILISTIC VOLCANIC HAZARD ASSESSMENT AT YUCCA MOUNTAIN

    Energy Technology Data Exchange (ETDEWEB)

    F.V. Perry

    2005-10-13

    Basaltic volcanism poses a potential hazard to the proposed Yucca Mountain nuclear waste repository because multiple episodes of basaltic volcanism have occurred in the Yucca Mountain region (YMR) in the past 11 Ma. Intervals between eruptive episodes average about 1 Ma. Three episodes have occurred in the Quaternary at approximately 1.1 Ma (5 volcanoes), 350 ka (2 volcanoes), and 80 ka (1 volcano). Because Yucca Mountain lies within the Basin and Range Province, a significant portion of the pre-Quaternary volcanic history of the YMR may be buried in alluvial-filled basins. An exceptionally high-resolution aeromagnetic survey and subsequent drilling program sponsored by the U.S. Department of Energy (DOE) began in 2004 and is gathering data that will enhance understanding of the temporal and spatial patterns of Pliocene and Miocene volcanism in the region (Figure 1). DOE has convened a ten-member expert panel of earth scientists that will use the information gathered to update probabilistic volcanic hazard estimates originally obtained by expert elicitation in 1996. Yucca Mountain is a series of north-trending ridges of eastward-tilted fault blocks that are bounded by north to northeast-trending normal faults. Topographic basins filled with up to 500 m of alluvium surround it to the east, south and west. In the past several decades, nearly 50 holes have been drilled in these basins, mainly for Yucca Mountain Project Site Characterization and the Nye County Early Warning Drilling Program. Several of these drill holes have penetrated relatively deeply buried (300-400 m) Miocene basalt; a Pliocene basalt dated at 3.8 Ma was encountered at a relatively shallow depth (100 m) in the northern Amargosa Desert (Anomaly B in Figure 1). The current drilling program is the first to specifically target and characterize buried basalt. Based on the new aeromagnetic survey and previous air and ground magnetic surveys (Connor et al. 2000; O'Leary et al. 2002), at least eight

  13. Eruptive History of the Rhyolitic Guangoche Volcano, Los Azufres Volcanic Field, Central Mexico

    Science.gov (United States)

    Rangel Granados, E.; Arce, J. L.; Macias, J. L.; Layer, P. W.

    2014-12-01

    Guangoche is a rhyolitic and polygenetic volcano with a maximum elevation of 2,760 meters above sea level. It is situated to the southwest of the Los Azufres Volcanic Field (LAVF), in the central sector of the Trans-Mexican Volcanic Belt. Guangoche volcano is the youngest volcano described within the LAVF. It shows a horseshoe shaped crater open to the south, with a central lava dome. Its eruptive history during late Pleistocene has been intense with six explosive eruptions that consists of: 1) A southwards sector collapse of the volcano that generated a debris avalanche deposit with megablocks of heterogenous composition; 2) A plinian-type eruption that generated a pumice fall deposit and pyroclastic density currents by column collapse at 30.6 ka; 3) A plinian-type eruption "White Pumice Sequence" (29 ka) that developed a 22-km-high eruptive column, with a MDR of 7.0 x 107 kg/s (vol. = 0.53 km3); 4) A dome-destruction event, "Agua Blanca Pyroclastic Sequence" at 26.7 ka, that deposited a block-and-ash flow deposit; 5) A subplinian-plinian type eruption "Ochre Pyroclastic Sequence" (<26 ka) with an important initial phreatomagmatic phase, that generated pyroclastic density currents and pumice fallouts. The subplinian-plinian event generated a 16-km-high eruptive column, with a MDR of 1.9 x 107 kg/s, and magma volume of 0.38 km3; 6) The eruptive history ended with a subplinian eruption (<<26 ka), that generated a multilayered fall deposit, that developed a 11-km-high eruptive column, with a MDR of 2.9 x 106 kg/s and a magma volume of 0.26 km3. Volcanic activity at Guangoche volcano has been intense and future activity should not be discarded. Unfortunately, the last two events have not been dated yet. Guangoche rhyolitic magma is characterized by low-Ba contents suggesting crystal mush extraction for their genesis.

  14. VEPP Exercise: Volcanic Activity and Monitoring of Pu`u `O`o, Kilauea Volcano, Hawaii

    Science.gov (United States)

    Rodriguez, L. A.

    2010-12-01

    A 10-week project will be tested during the Fall semester 2010, for a Volcanic Hazards elective course, for undergraduate Geology students of the University of Puerto Rico at Mayaguez. This exercise was developed during the Volcanoes Exploration Project: Pu`u `O`o (VEPP) Workshop, held on the Big Island of Hawaii in July 2010. For the exercise the students will form groups (of 2-4 students), and each group will be assigned a monitoring technique or method, among the following: seismic (RSAM data), deformation (GPS and tilt data), observations (webcam and lava flow maps), gas and thermal monitoring. The project is designed for Geology undergraduates who have a background in introductory geology, types of volcanoes and eruptions, magmatic processes, characteristics of lava flows, and other related topics. It is divided in seven tasks, starting with an introduction and demonstration of the VEPP website and the VALVE3 software, which is used to access monitoring data from the current eruption of Pu`u `O`o, Kilauea volcano, Hawaii. The students will also familiarize themselves with the history of Kilauea volcano and its current eruption. At least weekly the groups will acquire data (mostly near-real-time) from the different monitoring techniques, in the form of time series, maps, videos, and images, in order to identify trends in the data. The groups will meet biweekly in the computer laboratory to work together in the analysis and interpretation of the data, with the support of the instructor. They will give reports on the progress of the exercise, and will get feedback from the instructor and from the other expert groups. All groups of experts will relate their findings to the recent and current activity of Kilauea volcano, and the importance of their specific type of monitoring. The activity will culminate with a written report and an oral presentation. The last task of the project consists of a wrap-up volcano monitoring exercise, in which the students will

  15. Scattering matrices of volcanic ash particles of Mount St. Helens, Redoubt, and Mount Spurr Volcanoes

    Science.gov (United States)

    MuñOz, O.; Volten, H.; Hovenier, J. W.; Veihelmann, B.; van der Zande, W. J.; Waters, L. B. F. M.; Rose, W. I.

    2004-08-01

    We present measurements of the whole scattering matrix as a function of the scattering angle at a wavelength of 632.8 nm in the scattering angle range 3°-174° of randomly oriented particles taken from seven samples of volcanic ashes corresponding to four different volcanic eruptions: the 18 May 1980 Mount St. Helens eruption, the 1989-1990 Redoubt eruption, and the 18 August and 17 September 1992 Mount Spurr eruptions. The samples were collected at different distances from the vent. The samples studied contain large mass fractions of fine particles and were chosen to represent ash that could remain in the atmosphere for at least hours or days. They include fine ashfall samples that fell at a variety of distances from the volcano and pyroclastic flows that retained their fine fractions. Together, they represent a range of ashes likely to remain in the atmosphere in volcanic clouds following eruptions from convergent plate boundary volcanoes, Earth's most important group of explosive sources of ash. All measured scattering matrix elements are confined to rather limited domains when plotted as functions of the scattering angle following the general trends presented by irregular mineral particles. This similarity in the scattering behavior justifies the construction of an average scattering matrix for volcanic ash particles as a function of the scattering angle. To facilitate the use of the average scattering matrix for multiple-scattering calculations with polarization included, we present a synthetic scattering matrix based on the average scattering matrix for volcanic ashes and the assumption that the diffraction forward scattering peak is the same for randomly oriented nonspherical particles and projected-surface-area-equivalent spheres. This synthetic scattering matrix is normalized so that the average of its 1-1 element over all directions equals unity. It is available in the full range from 0° to 180° and can be used, for example, for interpretation of

  16. Impact of volcanic fluoride and SO/sub 7/ emissions from moderated activity volcanoes on the surrounding vegetation

    Energy Technology Data Exchange (ETDEWEB)

    Garrec, J.P.; Plebin, R.; Faivre-Pierret, R.X.

    1984-01-01

    Studies in the regions of the volcanoes Etna (Italy) and Masaya (Nicaragua) show that the continuous emissions of gaseous pollutants (HF and SO/sub 2/) from moderated activity volcanoes causes a chronic pollution in the surrounding vegetation with certain economical and ecological consequences. Reciprocally the measure of the pollutants in the plants growing in volcanic regions may be a simple and fast method to investigate some characteristics of the volcanic plume: for example, intensity of the emissions of gas, direction and extent of the plume. 12 references.

  17. Pleistocene to recent alkalic volcanism in the region of Sanganguey volcano, Nayarit, Mexico

    Science.gov (United States)

    Nelson, S. A.; Carmichael, I. S. E.

    1984-12-01

    Forty five cinder cones and associated lava flows have erupted within the last 300,000 years along five parallel lines through the calc-alkaline volcano, Sanganguey, in the northwestern segment of the Mexican Volcanic Belt. Lavas erupted from these cinder cones include ne- and hynormative alkali basalts, hawaiites, mugearites, and benmoreites. It is unusual that this suite has erupted in a calc-aikaline volcanic belt where volcanoes in the vicinity have been erupting calc-alkaline andesites, dacites and rhyodacites. Incompatible trace elements such Ba, Rb, Sr, and LREEs show little change with decreasing Mg, Ni, and Cr in the series alkali basalt to hawaiite, suggesting that simple crystal fractionation of observed phenocrysts has not been the dominant process in the derivation of the hawaiites from the alkali basalts. Petrographic evidence of magma mixing along with observed variation of trace element abundances suggests that the alkali basalts might represent mixtures of primitive magma with more evolved compositions. Crystal fractionation is capable of explaining major and most trace element trends in the series hawaiite — mugearite — benmoreite. However, such a process could only occur at pressure because of the requirement that clinopyroxene be a major crystallizing phase. The anomolous association of alkaline magmatism contemporaneously with calc-alkaline magmatism is probably related to the complex tectonic history associated with the rearrangement of plate boundaries in the vicinity of western Mexico.

  18. Field Courses for Volcanic Hazards Mapping at Parícutinand Jorullo Volcanoes (Mexico)

    Science.gov (United States)

    Victoria Morales, A.; Delgado Granados, H.; Roberge, J.; Farraz Montes, I. A.; Linares López, C.

    2007-05-01

    During the last decades, Mexico has suffered several geologic phenomena-related disasters. The eruption of El Chichón volcano in 1982 killed >2000 people and left a large number of homeless populations and severe economic damages. The best way to avoid and mitigate disasters and their effects is by making geologic hazards maps. In volcanic areas these maps should show in a simplified fashion, but based on the largest geologic background possible, the probable (or likely) distribution in time and space of the products related to a variety of volcanic processes and events, according to likely magnitude scenarios documented on actual events at a particular volcano or a different one with similar features to the volcano used for calibration and weighing geologic background. Construction of hazards maps requires compilation and acquisition of a large amount of geological data in order to obtain the physical parameters needed to calibrate and perform controlled simulation of volcanic events under different magnitude-scenarios in order to establish forecasts. These forecasts are needed by the authorities to plan human settlements, infrastructure, and economic development. The problem is that needs are overwhelmingly faster than the adjustments of university programs to include courses. At the Earth Science División of the Faculty of Engineering at the Universidad Nacional Autónoma de México, the students have a good background that permits to learn the methodologies for hazards map construction but no courses on hazards evaluations. Therefore, under the support of the university's Program to Support Innovation and Improvement of Teaching (PAPIME, Programa de Apoyo para la Innovación y Mejoramiento de la Enseñanza) a series of field-based intensive courses allow the Earth science students to learn what kind of data to acquire, how to record, and process in order to carry out hazards evaluations. This training ends with hazards maps that can be used immediately by the

  19. Volcanic Hazard Education through Virtual Field studies of Vesuvius and Laki Volcanoes

    Science.gov (United States)

    Carey, S.; Sigurdsson, H.

    2011-12-01

    Volcanic eruptions pose significant hazards to human populations and have the potential to cause significant economic impacts as shown by the recent ash-producing eruptions in Iceland. Demonstrating both the local and global impact of eruptions is important for developing an appreciation of the scale of hazards associated with volcanic activity. In order to address this need, Web-based virtual field exercises at Vesuvius volcano in Italy and Laki volcano in Iceland have been developed as curriculum enhancements for undergraduate geology classes. The exercises are built upon previous research by the authors dealing with the 79 AD explosive eruption of Vesuvius and the 1783 lava flow eruption of Laki. Quicktime virtual reality images (QTVR), video clips, user-controlled Flash animations and interactive measurement tools are used to allow students to explore archeological and geological sites, collect field data in an electronic field notebook, and construct hypotheses about the impacts of the eruptions on the local and global environment. The QTVR images provide 360o views of key sites where students can observe volcanic deposits and formations in the context of a defined field area. Video sequences from recent explosive and effusive eruptions of Carribean and Hawaiian volcanoes are used to illustrate specific styles of eruptive activity, such as ash fallout, pyroclastic flows and surges, lava flows and their effects on the surrounding environment. The exercises use an inquiry-based approach to build critical relationships between volcanic processes and the deposits that they produce in the geologic record. A primary objective of the exercises is to simulate the role of a field volcanologist who collects information from the field and reconstructs the sequence of eruptive processes based on specific features of the deposits. Testing of the Vesuvius and Laki exercises in undergraduate classes from a broad spectrum of educational institutions shows a preference for the

  20. A new volcano-structural map of the Virunga Volcanic Province, D.R.Congo and Rwanda

    Science.gov (United States)

    Poppe, Sam; Smets, Benoît; Albino, Fabien; Kervyn, François; Kervyn, Matthieu

    2013-04-01

    The Virunga Volcanic Province (VVP) is situated within the Western branch of the East African Rift system at the boundary of D.R.Congo, Rwanda and Uganda. The Western VVP comprises two active volcanoes, Nyamulagira and Nyiragongo. Six supposedly historically inactive volcanoes are present in the Central and Eastern VVP. Nyamulagira is recently the most active volcano on the African continent, with 30 eruptions since 1900, while Nyiragongo hosts a semi-permanent lava lake in its crater and fed a catastrophic lava flow in 2002. Additionally, numerous volcanic vents, fissures and cones are scattered on and around the main edifices. Except for geological maps from the colonial times and limited studies of historical eruptions, little is known about the volcano-tectonic structure and long term volcanic history of the VVP. A new Digital Elevation Model (TanDEM-X) with a resolution of 5 m, combined with SPOT and SAR images served as a base for the development of a new volcano-structural map for the entire VVP. A GIS data base was developed including the location of eruptive cones and fissures and the distribution of lava flows. The boundaries of historic and pre-historic lava flows and pyroclastic cones were traced from from interpretation of topographic and multispectral remote sensing data and re-analysis of ancient geological maps.Larger-scale lineaments interpreted as potential volcano-tectonic structures were also systematically mapped. All previously geochemically analyzed samples were localized. This GIS-based volcano-structural map will serve as a base for the quantitative characterization of recent and historic volcanic eruption products, such as pyroclastic cones and lava flows, of Nyamulagira and Nyiragongo, as well as for the assessment of potential Holocene activity in the Central and Eastern VVP. The orientation of feeder dykes inferred from cone alignments and morphology is used to identify the main volcanic structures and infer the locally dominant stress

  1. Physical properties of volcanic lightning: Constraints from magnetotelluric and video observations at Sakurajima volcano, Japan

    Science.gov (United States)

    Aizawa, Koki; Cimarelli, Corrado; Alatorre-Ibargüengoitia, Miguel A.; Yokoo, Akihiko; Dingwell, Donald B.; Iguchi, Masato

    2016-06-01

    The lightning generated by explosive volcanic eruptions is of interest not only as a promising technique for monitoring volcanic activity, but also for its broader implications and possible role in the origin of life on Earth, and its impact on the atmosphere and biosphere of the planet. However, at present the genetic mechanisms and physical properties of volcanic lightning remain poorly understood, as compared to our understanding of thundercloud lightning. Here, we present joint magnetotelluric (MT) data and video imagery that were used to investigate the physical properties of electrical discharges generated during explosive activity at Sakurajima volcano, Japan, and we compare these data with the characteristics of thundercloud lightning. Using two weeks of high-sensitivity, high-sample-rate MT data recorded in 2013, we detected weak electromagnetic signals radiated by volcanic lightning close to the crater. By carefully inspecting all MT waveforms that synchronized with visible flashes, and comparing with high-speed (3000 frame/s) and normal-speed (30 frame/s) videos, we identified two types of discharges. The first type consists of impulses (Type A) and is interpreted as cloud-to-ground (CG) lightning. The second type is characterized by weak electromagnetic variations with multiple peaks (Type B), and is interpreted as intra-cloud (IC) lightning. In addition, we observed a hybrid MT event wherein a continuous weak current accompanied Type A discharge. The observed features of volcanic lightning are similar to thunderstorm lightning, and the physical characteristics show that volcanic lightning can be treated as a miniature version of thunderstorm lightning in many respects. The overall duration, length, inter-stroke interval, peak current, and charge transfer all exhibit values 1-2 orders of magnitude smaller than those of thunderstorm lightning, thus suggesting a scaling relation between volcanic and thunderstorm lightning parameters that is independent of

  2. Characterization of volcanic deposits and geoarchaeological studies from the 1815 eruption of Tambora volcano

    Directory of Open Access Journals (Sweden)

    Igan Supriatman Sutawidjaja

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol1no1.20066aThe eruption of Tambora volcano on the island of Sumbawa in 1815 is generally considered as the largest and the most violent volcanic event in recorded history. The cataclysmic eruption occurred on 11 April 1815 was initiated by Plinian eruption type on 5 April and killed more than 90,000 people on Sumbawa and nearby Lombok. The type plinian eruptions occurred twice and ejected gray pumice and ash, to form stratified deposits as thick as 40-150 cm on the slopes and mostly distributed over the district west of the volcano. Following this, at about 7 pm, on 11 April the first pyroclastic surge was generated and progressively became greater extending to almost whole direction, mainly to the north, west, and south districts from the eruption center. The deadliest volcanic eruption buried ancient villages by pyroclastic surge and flow deposits in almost intact state, thus preserving important archaeological evidence for the period. High preservation in relatively stable conditions and known date of the eruptions provide approximate dating for the archaeological remains. Archaeological excavations on the site uncovered a variety of remains were relieved by ground penetrating radar (GPR to map structural remains of the ancient villages under the pyroclastic surge and flow deposits. These traverses showed that GPR could define structures as deep as 10 m (velocity 0.090 m/ns and could accurately map the thickness of the stratified volcanic deposits in the Tambora village area.    

  3. Characterization of volcanic deposits and geoarchaeological studies from the 1815 eruption of Tambora volcano

    Directory of Open Access Journals (Sweden)

    Igan Supriatman Sutawidjaja

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol1no1.20066aThe eruption of Tambora volcano on the island of Sumbawa in 1815 is generally considered as the largest and the most violent volcanic event in recorded history. The cataclysmic eruption occurred on 11 April 1815 was initiated by Plinian eruption type on 5 April and killed more than 90,000 people on Sumbawa and nearby Lombok. The type plinian eruptions occurred twice and ejected gray pumice and ash, to form stratified deposits as thick as 40-150 cm on the slopes and mostly distributed over the district west of the volcano. Following this, at about 7 pm, on 11 April the first pyroclastic surge was generated and progressively became greater extending to almost whole direction, mainly to the north, west, and south districts from the eruption center. The deadliest volcanic eruption buried ancient villages by pyroclastic surge and flow deposits in almost intact state, thus preserving important archaeological evidence for the period. High preservation in relatively stable conditions and known date of the eruptions provide approximate dating for the archaeological remains. Archaeological excavations on the site uncovered a variety of remains were relieved by ground penetrating radar (GPR to map structural remains of the ancient villages under the pyroclastic surge and flow deposits. These traverses showed that GPR could define structures as deep as 10 m (velocity 0.090 m/ns and could accurately map the thickness of the stratified volcanic deposits in the Tambora village area.    

  4. Pre-eruptive conditions of the ~31 ka rhyolitic magma of Tlaloc volcano, Sierra Nevada Volcanic Range, Central Mexico

    Science.gov (United States)

    Macias, J.; Arce, J.; Rueda, H.; Gardner, J.

    2008-12-01

    Tlaloc volcano is located at the northern tip of the Sierra Nevada Volcanic Range in Central Mexico. This Pleistocene to Recent volcanic range consists from north to south of Tlaloc-Telapón-Teyotl-Iztaccíhuatl-and- Popocatépetl volcanoes. While andesitic to barely dacitic volcanism dominates the southern part of the range (i.e. Popocatépetl and Iztaccíhuatl); dacitic and rare rhyolithic volcanism (i.e. Telapón, Tlaloc) dominates the northern end. The known locus of rhyolitic magmatism took place at Tlaloc volcano with a Plinian-Subplinian eruption that occurred 31 ka ago. The eruption emplaced the so-called multilayered fallout and pumiceous pyroclastic flows (~2 km3 DRE). The deposit consists of 95% vol. of juvenile particles (pumice + crystals) and minor altered lithics 5% vol. The mineral association of the pumice fragments (74-76 % wt. SiO2) consists of quartz + plagioclase + sanidine + biotite and rare oxides set in a glassy groundmass with voids. Melt inclusions in quartz phenocrysts suggest that prior to the eruption the rhyolitic contain ~7% of H2O and Toluca volcano (~6 km) some 50 km to the southwest.

  5. Radium isotopes in groundwater around Fuji Volcano, Japan -application for groundwater dating on volcanic area-

    Science.gov (United States)

    Ohta, T.; Mahara, Y.

    2010-12-01

    Young groundwater dating less than 100 years is possible to be obtained from environmental radioactivity with short half life, 3H+3He, 85Kr, or chemical material, CFC-12. The 3H+3He dating method is excellent method to estimate the residence time of shallow groundwater. The one of advantage of the method is small sample volume. The 3He in groundwater is originated by 3 sources, tritiogenic He, mantle He, radiogenic He produced in rock. Especially, as the contribution of the mantle He is greater than the radiogenic and triogenic, when 3H+3He dating apply for groundwater dating on volcanic area, we have to determine ratio of 3 sources. On the other hand, as 85Kr is only originated from atmosphere, it is excellent groundwater dating tracer on volcanic area. However, as 85Kr is ultra low concentration in groundwater, 85Kr is needed to separate from large amount of ground water about 10^5 L. Young groundwater dating by these methods has both advantages and disadvantages, but the disadvantages of the individual methods can be offset by using multiple tracers. Development of a lot of groundwater dating techniques is desired. Therefore, an application of radium isotopes which is simple origin to groundwater dating on volcanic area was tried. Ra-228 and Ra-226 are progenies of Th and U, respectively. The 228Ra/226Ra in ground waters depends on the Th/U in the relevant rocks. As the 228Ra and 226Ra in shallow groundwater on volcanic area are originated from only rock, and the collection of radium isotopes from groundwater is easier than that of 85Kr, implying that it is possible to be good tracer for volcanic area. We aim that groundwater age obtain from 228Ra/226Ra in groundwater and relevant rock on volcanic area. We determined that 228Ra/226Ra observed with river waters and the relevant rocks. The method applied for Kakitagawa around Fuji Volcano, Japan. The relevant rock of Kakitagawa is Mishima lava flow. Our method compared with 3H+3He dating. The residence time of

  6. A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc.

    Science.gov (United States)

    Klaver, Martijn; Carey, Steven; Nomikou, Paraskevi; Smet, Ingrid; Godelitsas, Athanasios; Vroon, Pieter

    2016-08-01

    This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely-operated vehicle that were analyzed for major element, trace element and Sr-Nd-Hf-Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave-bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52-60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low (206)Pb/(204)Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field.

  7. Reducing volcanic risk on Fogo Volcano, Cape-Verde, through a participatory approach: which out coming?

    Science.gov (United States)

    Texier-Teixeira, P.; Chouraqui, F.; Perrillat-Collomb, A.; Lavigne, F.; Cadag, J. R.; Grancher, D.

    2013-11-01

    This research paper presents the outcomes of the Work Package 5 (Socio-economical Vulnerability Assessment and Community-Based Disaster Risk Reduction) of the MIAVITA Research Program (MItigate and Assess risk from Volcanic Impact on Terrain and human Activities) conducted in Fogo Volcano, Cape-Verde. The study lasted for almost 3 yr (May 2010-January 2012) of which most of the time was spent in the village of Chã das Caldeiras, situated within the 9 km-wide caldera of the volcano inside the Fogo Natural Park. The objectives of the program included assessment of the vulnerability of the community at risk in terms of livelihoods, access to resources, and power relations between the local people and the different public and private institutions. These are important factors that need to be investigated in order to understand the root causes of vulnerability of the local people. This case study shows that the voluntary exposure of people at volcanic threats is linked with daily access to sources of livelihood specially agriculture and tourism. This is despite the perception of people of the risk on their lives and properties. In order to counter the factors of vulnerability, the study also aimed to identify and enhance local capacities. To achieve such objective, a Participatory 3-Dimensional Mapping (P3DM) activity was conducted to facilitate the dialogue between the local people and the different stakeholders as well as to prepare plans and measures to reduce volcanic risk. The P3DM was a half success considering that it has not yet led to an operational plan which takes into account the local capacities. The main reasons included (1) the non-participative aspect of the project at the beginning which should have identified priorities for people and let them lead the project to ensure the sustainability (2) deep conflicts within the community which complicated the focus group discussions around the 3-D map, and the difficulties to involve more marginalized people

  8. Reducing volcanic risk on Fogo Volcano, Cape Verde, through a participatory approach: which outcome?

    Science.gov (United States)

    Texier-Teixeira, P.; Chouraqui, F.; Perrillat-Collomb, A.; Lavigne, F.; Cadag, J. R.; Grancher, D.

    2014-09-01

    This research paper presents the outcomes of Work Package 5 (socio-economical vulnerability assessment and community-based disaster risk reduction) of the MIAVITA (MItigate and Assess risk from Volcanic Impact on Terrain and human Activities) research programme conducted on Fogo Volcano, Cape Verde. The study lasted for almost 3 years (May 2010 to January 2012), of which most of the time was spent in the village of Chã das Caldeiras, situated within the 9 km wide caldera of the volcano inside Fogo Natural Park. The objectives of the programme included assessment of the vulnerability of the community at risk in terms of livelihoods, access to resources, and power relations between the local people and the different public and private institutions. These are important factors that need to be investigated in order to understand the root causes of vulnerability of the local people. This case study shows that the voluntary exposure of people to volcanic threats is linked to daily access to sources of livelihood, especially agriculture and tourism. This is despite the perception of people of the risk to their lives and properties. In order to counter the factors of vulnerability, the study also aimed to identify and enhance local capacities. To achieve such an objective, a participatory three-dimensional mapping (P3DM) activity was conducted to facilitate the dialogue between the local people and the different stakeholders as well as to prepare plans and measures to reduce volcanic risk. The P3DM was a half success considering that it has not yet led to an operational plan which takes into account the local capacities. The main reasons included (1) the non-participatory aspect of the project at the beginning which should have identified priorities for people and let them lead the project to ensure the sustainability of (2) deep conflicts within the community which complicated the focus group discussions around the 3-D map, and the difficulties in involving more

  9. Reducing volcanic risk on Fogo Volcano, Cape-Verde, through a participatory approach: which out coming?

    Directory of Open Access Journals (Sweden)

    P. Texier-Teixeira

    2013-11-01

    Full Text Available This research paper presents the outcomes of the Work Package 5 (Socio-economical Vulnerability Assessment and Community-Based Disaster Risk Reduction of the MIAVITA Research Program (MItigate and Assess risk from Volcanic Impact on Terrain and human Activities conducted in Fogo Volcano, Cape-Verde. The study lasted for almost 3 yr (May 2010–January 2012 of which most of the time was spent in the village of Chã das Caldeiras, situated within the 9 km-wide caldera of the volcano inside the Fogo Natural Park. The objectives of the program included assessment of the vulnerability of the community at risk in terms of livelihoods, access to resources, and power relations between the local people and the different public and private institutions. These are important factors that need to be investigated in order to understand the root causes of vulnerability of the local people. This case study shows that the voluntary exposure of people at volcanic threats is linked with daily access to sources of livelihood specially agriculture and tourism. This is despite the perception of people of the risk on their lives and properties. In order to counter the factors of vulnerability, the study also aimed to identify and enhance local capacities. To achieve such objective, a Participatory 3-Dimensional Mapping (P3DM activity was conducted to facilitate the dialogue between the local people and the different stakeholders as well as to prepare plans and measures to reduce volcanic risk. The P3DM was a half success considering that it has not yet led to an operational plan which takes into account the local capacities. The main reasons included (1 the non-participative aspect of the project at the beginning which should have identified priorities for people and let them lead the project to ensure the sustainability (2 deep conflicts within the community which complicated the focus group discussions around the 3-D map, and the difficulties to involve more

  10. Utilizing NASA Earth Observations to Model Volcanic Hazard Risk Levels in Areas Surrounding the Copahue Volcano in the Andes Mountains

    Science.gov (United States)

    Keith, A. M.; Weigel, A. M.; Rivas, J.

    2014-12-01

    Copahue is a stratovolcano located along the rim of the Caviahue Caldera near the Chile-Argentina border in the Andes Mountain Range. There are several small towns located in proximity of the volcano with the two largest being Banos Copahue and Caviahue. During its eruptive history, it has produced numerous lava flows, pyroclastic flows, ash deposits, and lahars. This isolated region has steep topography and little vegetation, rendering it poorly monitored. The need to model volcanic hazard risk has been reinforced by recent volcanic activity that intermittently released several ash plumes from December 2012 through May 2013. Exposure to volcanic ash is currently the main threat for the surrounding populations as the volcano becomes more active. The goal of this project was to study Copahue and determine areas that have the highest potential of being affected in the event of an eruption. Remote sensing techniques were used to examine and identify volcanic activity and areas vulnerable to experiencing volcanic hazards including volcanic ash, SO2 gas, lava flow, pyroclastic density currents and lahars. Landsat 7 Enhanced Thematic Mapper Plus (ETM+), Landsat 8 Operational Land Imager (OLI), EO-1 Advanced Land Imager (ALI), Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Shuttle Radar Topography Mission (SRTM), ISS ISERV Pathfinder, and Aura Ozone Monitoring Instrument (OMI) products were used to analyze volcanic hazards. These datasets were used to create a historic lava flow map of the Copahue volcano by identifying historic lava flows, tephra, and lahars both visually and spectrally. Additionally, a volcanic risk and hazard map for the surrounding area was created by modeling the possible extent of ash fallout, lahars, lava flow, and pyroclastic density currents (PDC) for future eruptions. These model results were then used to identify areas that should be prioritized for disaster relief and evacuation orders.

  11. Photosynthesis within Mars' volcanic craters?: Insights from Cerro Negro Volcano, Nicaragua

    Science.gov (United States)

    Rogers, K. L.; Hynek, B. M.; McCollom, T. M.

    2011-12-01

    Discrete locales of sulfate-rich bedrocks exist on Mars and in many cases represent the products of acid-sulfate alteration of martian basalt. In some places, the products have been attributed to hydrothermal processes from local volcanism. In order to evaluate the habitability of such an environment, we are investigating the geochemical and biological composition of active fumaroles at Cerro Negro Volcano, Nicaragua, where fresh basaltic cinders similar in composition to martian basalts are altered by acidic, sulfur-bearing gases. Temperatures at active fumaroles can reach as high as 400°C and the pH of the steam ranges from Bacterial diversity. Cloning of PCR-amplified 16S rRNA genes reveals a diverse community of Bacteria, with eight phyla represented. The most common bacterial sequences belonged to the Cyanobacteria and Ktedonobacteria, however Actinobacteria, alpha-Proteobacteria and Acidobacteria were also identified. Many of the cyanobacterial sequences were similar to those of the eukaryotic Cyanidiales, red algae that inhabit acidic, geothermal environments. Many of sequences related to Ktedonobacteria and Actinobacteria have also been found in acid mine drainage environments. The Archaeal community was far less diverse, with sequences matching those of unclassified Desulfurococcales and unclassified Thermoprotei. These sequences were more distant from isolated species than the bacterial sequences. Similar bacterial and archaeal communities have been found in hot spring environments in Yellowstone National Park, Greenland, Iceland, New Zealand and Costa Rica. Some of Mars' volcanoes were active for billions of years and by analogy to Cerro Negro, may have hosted photosynthetic organisms that could have been preserved in alteration mineral assemblages. Even on a generally cold and dry Mars, volcanic craters likely provided long-lived warm and wet conditions and should be a key target for future exploration assessing habitability.

  12. The impact of persistent volcanic degassing on vegetation: A case study at Turrialba volcano, Costa Rica

    Science.gov (United States)

    Tortini, R.; van Manen, S. M.; Parkes, B. R. B.; Carn, S. A.

    2017-07-01

    Although the impacts of large volcanic eruptions on the global environment have been frequently studied, the impacts of lower tropospheric emissions from persistently degassing volcanoes remain poorly understood. Gas emissions from persistent degassing exceed those from sporadic eruptive activity, and can have significant long-term (years to decades) effects on local and regional scales, both on humans and the environment. Here, we exploit a variety of high temporal and high spatial resolution satellite-based time series and complementary ground-based measurements of element deposition and surveys of species richness, to enable a comprehensive spatio-temporal assessment of sulfur dioxide (SO2) emissions and their associated impacts on vegetation at Turrialba volcano (Costa Rica) from 2000 to 2013. We observe increased emissions of SO2 coincident with a decline in vegetation health downwind of the vents, in accordance with the prevalent wind direction at Turrialba. We also find that satellite-derived vegetation indices at various spatial resolutions are able to accurately define the vegetation kill zone, the extent of which is independently confirmed by ground-based sampling, and monitor its expansion over time. In addition, ecological impacts in terms of vegetation composition and diversity and physiological damage to vegetation, all spatially correspond to fumigation by Turrialba's plume. This study shows that analyzing and relating satellite observations to conditions and impacts on the ground can provide an increased understanding of volcanic degassing, its impacts in terms of the long-term vegetation response and the potential of satellite-based monitoring to inform hazard management strategies related to land use.

  13. Stability Evaluation Of Previous Volcanic Edifice Collapse At Pico De Orizaba Volcano, Mexico, Using Geotechnical Techniques

    Science.gov (United States)

    Concha-Dimas, A.; Watters, R. J.

    2001-12-01

    Pico de Orizaba volcano has collapsed twice during its geologic evolution (Carrasco-Nuñez, 1997). The initial stage of evolution for this volcano is known as the Torrecillas cone that collapsed 0.21 Ma b.p., and the related deposits formed the Jamapa avalanche which traveled eastward 75 km. A second, superimposed constructional stage is the Espolón de Oro cone that also ended with a collapse 20 000 years b.p., forming the Tetelzingo avalanche-lahar that traveled 85 km. Samples from the remains of old summit cores and their corresponding collapse deposits were collected and tested in order to obtain strength parameters of altered rock from old volcanic edifices. Hydrothermal alteration and variations of strength of the two avalanche deposits were correlated with the strength values and alterations from the in situ corresponding sources. Strength values: Hoek and Brown's parameters, Uniaxial Compressive Strength (50-300 kPa), cohesion (480-2000 kPa), angle of friction (6° - 35° ); and degree of alteration give insights of rock mass quality and maximum intact rock strengths of the edifice rock mass. These values provide the upper limits for numerical model input parameter values for evaluation of flank stability. Rock strength from numerical model of previous failures can be compared with those obtained for the rock mass and intact rock of the actual edifice. This would permit the assessment of future avalanche hazards.

  14. Volcanic hazard zonation of the Nevado de Toluca volcano, México

    Science.gov (United States)

    Capra, L.; Norini, G.; Groppelli, G.; Macías, J. L.; Arce, J. L.

    2008-10-01

    The Nevado de Toluca is a quiescent volcano located 20 km southwest of the City of Toluca and 70 km west of Mexico City. It has been quiescent since its last eruptive activity, dated at ˜ 3.3 ka BP. During the Pleistocene and Holocene, it experienced several eruptive phases, including five dome collapses with the emplacement of block-and-ash flows and four Plinian eruptions, including the 10.5 ka BP Plinian eruption that deposited more than 10 cm of sand-sized pumice in the area occupied today by Mexico City. A detailed geological map coupled with computer simulations (FLOW3D, TITAN2D, LAHARZ and HAZMAP softwares) were used to produce the volcanic hazard assessment. Based on the final hazard zonation the northern and eastern sectors of Nevado de Toluca would be affected by a greater number of phenomena in case of reappraisal activity. Block-and-ash flows will affect deep ravines up to a distance of 15 km and associated ash clouds could blanket the Toluca basin, whereas ash falls from Plinian events will have catastrophic effects for populated areas within a radius of 70 km, including the Mexico City Metropolitan area, inhabited by more than 20 million people. Independently of the activity of the volcano, lahars occur every year, affecting small villages settled down flow from main ravines.

  15. Detecting hidden volcanic explosions from Mt. Cleveland Volcano, Alaska with infrasound and ground-couples airwaves

    Science.gov (United States)

    De Angelis, Slivio; Fee, David; Haney, Matthew; Schneider, David

    2012-01-01

    In Alaska, where many active volcanoes exist without ground-based instrumentation, the use of techniques suitable for distant monitoring is pivotal. In this study we report regional-scale seismic and infrasound observations of volcanic activity at Mt. Cleveland between December 2011 and August 2012. During this period, twenty explosions were detected by infrasound sensors as far away as 1827 km from the active vent, and ground-coupled acoustic waves were recorded at seismic stations across the Aleutian Arc. Several events resulting from the explosive disruption of small lava domes within the summit crater were confirmed by analysis of satellite remote sensing data. However, many explosions eluded initial, automated, analyses of satellite data due to poor weather conditions. Infrasound and seismic monitoring provided effective means for detecting these hidden events. We present results from the implementation of automatic infrasound and seismo-acoustic eruption detection algorithms, and review the challenges of real-time volcano monitoring operations in remote regions. We also model acoustic propagation in the Northern Pacific, showing how tropospheric ducting effects allow infrasound to travel long distances across the Aleutian Arc. The successful results of our investigation provide motivation for expanded efforts in infrasound monitoring across the Aleutians and contributes to our knowledge of the number and style of vulcanian eruptions at Mt. Cleveland.

  16. Velocity structure of the crust and upper mantle at the northern group of Kamchatka volcanoes (Based on the travel time of P-waves from volcanic earthquakes)

    Science.gov (United States)

    Slavina, L. B.; Pivovarova, N. B.; Senyukov, S. L.

    2012-12-01

    The results of a calculation of the P-wave ( V P ) velocity fields are presented on the basis of the method of the reversible wave and the TAU parameter characterizing the V P / V S ratio of seismic waves from the local volcanic earthquakes that occurred at the northern group of Kamchatka volcanoes in 2005-2007. The 3D velocity cross sections were constructed along the SW-NE-trending volcanic group from the Ploskii Tolbachik volcano in the southwest up to the Shiveluch volcano in the northeast. The change of velocity field in time and depth is found. The problems of relating these changes to volcanic activity is reviewed.

  17. Composition of volcanic gases emitted during repeating Vulcanian eruption stage of Shinmoedake, Kirishima volcano, Japan

    Science.gov (United States)

    Shinohara, H.

    2013-06-01

    Volcanic gas compositions of Shinmoedake, Kirishima volcano, Japan were measured by Multi-GAS during the persistent degassing period with repeating Vulcanian eruptions from March 2011 to March 2012. In order to avoid risks due to eruptions, the measurements were performed with the Unmanned Aerial Vehicles (UAV) that fly through the plume with the Multi-GAS and by an automatic Multi-GAS monitoring station installed 5 km away from the summit. Based on the UAV measurements on May 18, 2011, most of the major volcanic gas components were quantified as CO2/SO2 = 8, SO2/H2S = 0.8, H2O/CO2 = 70 and H2/SO2 = 0.03 (mol ratio), and the SO2/H2S ratio of the plume was quantified as 8 on March 15, 2011. The Multi-GAS monitoring station occasionally detected a dilute plume with an SO2/H2S ratio ranging from 0.8 to 3.3 from April 2011 to March 2012. The decrease of the SO2/H2S ratio from March 15, 2011, to May 18, 2011, is interpreted as the result of a ten times increase of the degassing pressure. Based on the SO2 fluxes and the gas compositions, the conduit magma convection is considered to be the gas supply mechanism at the Shinmoedake, and the degassing pressure changes are attributed to the change of depth of the convecting magma column top.

  18. Localised magmatic constraints on continental back-arc volcanism in southern Mendoza, Argentina: the Santa Maria Volcano

    Science.gov (United States)

    Espanon, Venera R.; Chivas, Allan R.; Turner, Simon P.; Kinsley, Leslie P. J.; Dosseto, Anthony

    2016-11-01

    The Payún Matrú Volcanic Field constitutes part of the continental back-arc in Argentina. This volcanic field has been the focus of several regional investigations; however, geochemical analysis of recent volcanoes (<8 ka) at the scale of an individual volcano has not been conducted. We present a morphological description for the Santa Maria Volcano in addition to results from major and trace element analysis and 238U-230Th-226Ra disequilibria. The trace element evidence suggests that the Santa Maria magmatic source has a composition similar to that of the local intraplate end member (resembling an ocean island basalt-like source), with a slight contribution from subduction-related material. The U-series analyses suggest a high 226Ra excess over 230Th for this volcano, which is not derived from a shallow process such as hydrothermal alteration or upper crustal contamination. Furthermore, intermediate-depth processes such as fractional crystallisation have been inferred for the Santa Maria Volcano, but they are not capable of producing the 226Ra excess measured. The 226Ra excess is explained by deep processes like partial melting of mantle lithologies with some influence from subducted Chilean trench sediments. Due to the short half-life of 226Ra (1600 years), we infer that fast magma ascent rates are required to preserve the high 226Ra excess.

  19. Geodetic constraints on volcanic plume height at Grímsvötn volcano, Iceland

    Science.gov (United States)

    Hreinsdóttir, Sigrún; Sigmundsson, Freysteinn; Roberts, Matthew; Björnsson, Halldór; Grapenthin, Ronni; Arason, Pórdur; Árnadóttir, Thóra; Hólmjárn, Jósef; Geirsson, Halldór; Bennett, Richard; Gudmundsson, Magnús; Oddsson, Björn; Ófeigsson, Benedikt; Villemin, Thierry; Jónsson, Torsteinn; Sturkell, Erik; Höskuldsson, Ármann; Larsen, Gudrún; Thordarson, Thor; Óladóttir, Bergrún

    2014-05-01

    In 2011 a VEI 4 explosive eruption took place at Grímsvötn volcano, Iceland. Grímsvötn is a subglacial basaltic volcano beneath the Vatnajökull ice cap. It is Iceland's most frequently erupting volcano, with recent eruptions in 1983, 1998, 2004, and 2011. The volcano has a low seismic velocity anomaly down to about 3 km depth, interpreted as a magma chamber. A continuous GPS station and a tiltmeter are located on a nunatak, Mount Grímsfjall, which protrudes from the ice at the southern rim of the caldera. The 21-28 May 2011 eruption was Grímsvötn's largest since 1873, resulting in airspace closure in northern Europe and the cancellation of about 900 passenger flights. The eruption was preceded by gradual inflation following the 2004 eruption and progressive increase in seismicity. Kinematic 1 Hz solutions were derived for the position of the GPS station in the hours immediately before and during the 2011 eruption. The onset of deformation preceded the eruption by one hour and reached maximum of 0.57 m within 48 hours. Throughout the eruption the GPS station moved consistently in direction N38.4+/-0.5W, opposite to the direction of movements during the 2004-2011 inter eruptive phase. The deformation characteristics suggest that the signal was mostly due to pressure change in a source at 1.7 +/- 0.2 km depth. We use the geodetic measurements to infer co-eruptive pressure change in the magma chamber using the Mogi model. The rate of pressure drop is then used to estimate the magma flow rate from the chamber. Numerous studies have shown that plume height in explosive eruptions can be related to magma discharge. Using an empirical relationship between the volcanic plume height and magma flow rate (Mastin et al., 2009) we estimate the evolution of the plume height from the geodetic data. Two weather radars monitored the height of the volcanic plume during the eruption. A strong initial plume with peaks at 20-25 km was followed by a declining, pulsating activity

  20. The Volcano Disaster Assistance Program: Working with International Partners to Reduce the Risk from Volcanic Eruptions Worldwide

    Science.gov (United States)

    Mayberry, G. C.; Pallister, J. S.

    2015-12-01

    The Volcano Disaster Assistance Program (VDAP) is a joint effort between USGS and the U.S. Agency for International Development's (USAID) Office of U.S. Foreign Disaster Assistance (OFDA). OFDA leads and coordinates disaster responses overseas for the U.S. government and is a unique stakeholder concerned with volcano disaster risk reduction as an international humanitarian assistance donor. One year after the tragic eruption of Nevado del Ruiz in 1985, OFDA began funding USGS to implement VDAP. VDAP's mission is to reduce the loss of life and property and limit the economic impact from foreign volcano crises, thereby preventing such crises from becoming disasters. VDAP fulfills this mission and complements OFDA's humanitarian assistance by providing crisis response, capacity-building, technical training, and hazard assessments to developing countries before, during, and after eruptions. During the past 30 years, VDAP has responded to more than 27 major volcanic crises, built capacity in 12+ countries, and helped counterparts save tens of thousands of lives and hundreds of millions of dollars in property. VDAP responses have evolved as host-country capabilities have grown, but the pace of work has not diminished; as a result of VDAP's work at 27 volcanoes in fiscal year 2014, more than 1.3 million people who could have been impacted by volcanic activity benefitted from VDAP assistance, 11 geological policies were modified, 188 scientists were trained, and several successful eruption forecasts were made. VDAP is developing new initiatives to help counterparts monitor volcanoes and communicate volcanic risk. These include developing the Eruption Forecasting Information System (EFIS) to learn from compiled crisis data from 30 years of VDAP responses, creating event trees to forecast eruptions at restless volcanoes, and exploring the use of unmanned aerial systems for monitoring. The use of these new methods, along with traditional VDAP assistance, has improved VDAP

  1. Poás volcano: Relationships between diffuse vs active CO degassing and long term volcanic activity.

    Science.gov (United States)

    Epiard, Matthieu; Avard, Geoffroy; de Moor, Marteen; Martinez Cruz, Maria; Bakkar, Henriette

    2017-04-01

    Active volcanoes exhibit diffuse gas emanations through the ground. Carbon dioxide is one of the most abundant species, in addition to the gases actively released through channelized vents. CO₂ diffuse degassing is not always correlated to volcanic activity but CO₂ diffuse vs active degassing ratios appears to show interesting behavior regarding fluctuations in volcanic activity. CO₂ diffuse degassing data were obtained at Poás volcano (Costa Rica) in 2011 using the accumulation chamber method with the aim of estimating the total diffuse CO₂ budget. This result was compared to active degassing data, as well as to previous CO₂ diffuse degassing data measured between 2000 and 2004, when Poás entered in a stage of enhanced volcanic activity. Results show a dramatic decrease in CO₂ diffuse degassing rate between 2000 and 2011 of more than 500t/d, following an increasing trend in total gas emission and power output between September 1995 and the end of 2001. Thus, the ratio of diffuse to active degassing has dramatically decreased with the increase of volcanic activity and occurrence of phreatic eruption. Two main hypothesis could explain those results: 1) Either the rising of magma to shallower levels allows the gas to be better channelized due to enhanced permeability and conduit opening, or 2) Poás volcano might experience a periodic pattern of hydrothermal sealing/overpressure/eruption that allows the system to shift from a regimen of passive degassing to active degassing.

  2. Volcanic ash hazard climatology for an eruption of Hekla Volcano, Iceland

    Science.gov (United States)

    Leadbetter, Susan J.; Hort, Matthew C.

    2011-01-01

    Ash produced by a volcanic eruption on Iceland can be hazardous for both the transatlantic flight paths and European airports and airspace. In order to begin to quantify the risk to aircraft, this study explored the probability of ash from a short explosive eruption of Hekla Volcano (63.98°N, 19.7°W) reaching European airspace. Transport, dispersion and deposition of the ash cloud from a three hour 'explosive' eruption with an initial plume height of 12 km was simulated using the Met Office's Numerical Atmospheric-dispersion Modelling Environment, NAME, the model used operationally by the London Volcanic Ash Advisory Centre. Eruptions were simulated over a six year period, from 2003 until 2008, and ash clouds were tracked for four days following each eruption. Results showed that a rapid spread of volcanic ash is possible, with all countries in Europe facing the possibility of an airborne ash concentration exceeding International Civil Aviation Organization (ICAO) limits within 24 h of an eruption. An additional high impact, low probability event which could occur is the southward spread of the ash cloud which would block transatlantic flights approaching and leaving Europe. Probabilities of significant concentrations of ash are highest to the east of Iceland, with probabilities exceeding 20% in most countries north of 50°N. Deposition probabilities were highest at Scottish and Scandinavian airports. There is some seasonal variability in the probabilities; ash is more likely to reach southern Europe in winter when the mean winds across the continent are northerly. Ash concentrations usually remain higher for longer during summer when the mean wind speeds are lower.

  3. Mercury speciation, fluxes, and fate in the volcanically acidified fluids of Copahue volcano, Argentina

    Science.gov (United States)

    Kading, T.; Varekamp, J. C.; Andersson, M.; Balcom, P.; Mason, R. P.

    2010-12-01

    The behavior of mercury in volcanic acid springs and acidified rivers is poorly known, despite the potential impact this vector of contamination has on local surface and ground water quality. Mercury was measured in a volcanically acidified river system (pHNeuquen province of Argentina, which discharges into a large glacial lake (Lake Caviahue, pH 2.2-3.0). The Hg concentration ranged from 2 - 600 pM throughout the fluvial system. Mercury in the hot, hyperacidic source fluids was dominated by dissolved ionic species, with only 2% of total mercury as dissolved elemental mercury, and 11% being particulate bound. The Hg flux from the volcano, determined from river water flux measurements and Hg concentrations, was modest and varied between the 3/2008 and 3/2009 sampling campaigns resp. from 0.7 to 1.1 moles/year. The Hg:S ratio of the acid fluids was ~10-8, several orders of magnitude lower than that typically found in volcanic plumes and fumaroles. The small Hg flux and low Hg:S values suggest that the system is either inherently Hg-poor or has lost Hg through vapor loss deeper in the hydrothermal system. Support for the latter comes from high Hg concentrations in geothermal vents and mudpots on the flank of the mountain (24 - 55 ppm Hg). Mercury concentrations decreased conservatively downstream in the river as based on Hg/Cl and Hg/SO4. Non-conservative depletion occurs in the less acidic Lake Caviahue, suggesting that mercury is removed from the water column by sorption to organic matter or other phases. Mercury analyses of a short lake sediment core confirm this (Hg = 0.01 to 0.70 ppm). No evidence was found for preferential uptake of mercury by jarosite, schwertmannite, or goethite, although the latter two phases precipitate in the most distal and Hg-depleted section of the fluvial system.

  4. The Massive Compound Cofre de Perote Shield Volcano: a Volcanological Oddity in the Eastern Mexican Volcanic Belt

    Science.gov (United States)

    Siebert, L.; Carrasco-Nunez, G.; Diaz-Castellon, R.; Rodriguez, J. L.

    2007-12-01

    Cofre de Perote volcano anchors the northern end of the easternmost of several volcanic chains orthogonal to the E-W trend of the Mexican Volcanic Belt (MVB). Its structure, geochemistry, and volcanic history diverge significantly from that of the large dominantly andesitic stratovolcanoes that have been the major focus of research efforts in the MVB. Andesitic-trachyandesitic to dacitic-trachydacitic effusive activity has predominated at Cofre de Perote, forming a massive low-angle compound shield volcano that dwarfs the more typical smaller shield volcanoes of the central and western MVB. The 4282-m-high volcano overlooking Xalapa, the capital city of the State of Veracruz, has a diameter of about 30 km and rises more than 3000 m above the coastal plain to the east. Repeated edifice collapse has left massive horseshoe-shaped scarps that truncate the eastern side of the edifice. Five major evolutionary stages characterize the growth of this compound volcano: 1) emplacement of a multiple-vent dome complex forming the basal structure of Cofre de Perote around 1.9-1.3 Ma; 2) construction of the basal part of the compound shield volcano from at least two main upper-edifice vents at about 400 ka; 3) effusion of the summit dome-like lavas through multiple vents at ca. 240 ka; 4) eruption of a large number of geochemically diverse, alkaline and calc-alkaline Pleistocene-to-Holocene monogenetic cones (likely related to regional volcanism) through the flanks of the Cofre de Perote edifice; 5) late-stage, large-volume edifice collapse on at least two occasions (ca. 40 ka and ca. 10 ka), producing long-runout debris avalanches that traveled to the east. An undated tephra layer from Cofre de Perote overlies deposits likely of the youngest collapse. Cofre de Perote is one of several volcanoes in the roughly N-S-trending chain that has undergone major edifice collapse. As with Citlaltepetl (Pico de Orizaba) and Las Cumbres volcanoes, Cofre de Perote was constructed at the

  5. The temporal evolution of back-arc magmas from the Auca Mahuida shield volcano (Payenia Volcanic Province, Argentina)

    Science.gov (United States)

    Pallares, Carlos; Quidelleur, Xavier; Gillot, Pierre-Yves; Kluska, Jean-Michel; Tchilinguirian, Paul; Sarda, Philippe

    2016-09-01

    In order to better constrain the temporal volcanic activity of the back-arc context in Payenia Volcanic Province (PVP, Argentina), we present new K-Ar dating, petrographic data, major and trace elements from 23 samples collected on the Auca Mahuida shield volcano. Our new data, coupled with published data, show that this volcano was built from about 1.8 to 1.0 Ma during five volcanic phases, and that Auca Mahuida magmas were extracted from, at least, two slightly different OIB-type mantle sources with a low partial melting rate. The first one, containing more garnet, was located deeper in the mantle, while the second contains more spinel and was thus shallower. The high-MgO basalts (or primitive basalts) and the low-MgO basalts (or evolved basalts), produced from the deeper and shallower lherzolite mantle sources, respectively, are found within each volcanic phase, suggesting that both magmatic reservoirs were sampled during the 1 Myr lifetime of the Auca Mahuida volcano. However, a slight increase of the proportion of low-MgO basalts, as well as of magmas sampled from the shallowest source, can be observed through time. Similar overall petrological characteristics found in the Pleistocene-Holocene basaltic rocks from Los Volcanes and Auca Mahuida volcano suggest that they originated from the same magmatic source. Consequently, it can be proposed that the thermal asthenospheric anomaly is probably still present beneath the PVP. Finally, our data further support the hypothesis that the injection of hot asthenosphere with an OIB mantle source signature, which was triggered by the steepening of the Nazca subducting plate, induced the production of a large volume of lavas within the PVP since 2 Ma.

  6. Knowledge Sharing and Collaboration in Volcanic Risk Mitigation at Galeras Volcano, Colombia: A Participative Workshop to Reduce Volcanic Risk

    Science.gov (United States)

    Sheridan, M. F.; Cordoba, G. A.

    2009-12-01

    Galeras has been in nearly constant activity during modern historic times (roughly the past 500 years). Approximately 10,000 people live within an area designated as the highest-hazard and nearly 400,000 people are within areas of potential harmful effects. A wide variety of stakeholders are affected by the hazards, including: farmers, indigenous villagers, and people in urban environments. Hazards assessment and volcano monitoring are the responsibility of the Colombian Geological Survey (INGEOMINAS), whereas decisions regarding mitigation and response procedures are the responsibility of various governmental offices and the national emergency system (SNPAD). According to the current plan, when the risk level rises to a high level the people in the highest risk zone are required to evacuate. The volcano currently is in a very active, but fluctuating, condition and a future large eruption in a medium time frame (years to decades) is possible. There is a growing level of discomfort among many of the affected groups, including indigenous communities, farmers, and urban dwellers, related to the risk assessment. The general opinion prior to July 2009 was quite polarized as the decision makers saw the people of the region as poorly prepared to understand this hazard, whereas the population felt that their views were not being heard. The result was that the people in the hazardous areas decided not to evacuate, even during the current period of explosive activity. To resolve this situation the University of Nariño (Colombia) and the State University of New York at Buffalo organized a workshop named "Knowledge, Sharing and Collaboration in Volcanic Risk Mitigation at Galeras Volcano, Colombia" that was held in Pasto (Colombia), between 6 and 11 July, 2009. The general objective of this workshop was to analyze the existing hazard maps and safety plans for Galeras and form a bridge connecting scientists, decision makers, and other stake holders to promote a better

  7. Isotopically (δ13C and δ18O) heavy volcanic plumes from Central Andean volcanoes: a field study

    Science.gov (United States)

    Schipper, C. Ian; Moussallam, Yves; Curtis, Aaron; Peters, Nial; Barnie, Talfan; Bani, Philipson; Jost, H. J.; Hamilton, Doug; Aiuppa, Alessandro; Tamburello, Giancarlo; Giudice, Gaetano

    2017-08-01

    Stable isotopes of carbon and oxygen in volcanic gases are key tracers of volatile transfer between Earth's interior and atmosphere. Although important, these data are available for few volcanoes because they have traditionally been difficult to obtain and are usually measured on gas samples collected from fumaroles. We present new field measurements of bulk plume composition and stable isotopes (δ13CCO2 and δ18OH2O+CO2) carried out at three northern Chilean volcanoes using MultiGAS and isotope ratio infrared spectroscopy. Carbon and oxygen in magmatic gas plumes of Lastarria and Isluga volcanoes have δ13C in CO2 of +0.76‰ to +0.77‰ (VPDB), similar to slab carbonate; and δ18O in the H2O + CO2 system ranging from +12.2‰ to +20.7‰ (VSMOW), suggesting significant contributions from altered slab pore water and carbonate. The hydrothermal plume at Tacora has lower δ13CCO2 of -3.2‰ and δ18OH2O+CO2 of +7.0‰, reflecting various scrubbing, kinetic fractionation, and contamination processes. We show the isotopic characterization of volcanic gases in the field to be a practical complement to traditional sampling methods, with the potential to remove sampling bias that is a risk when only a few samples from accessible fumaroles are used to characterize a given volcano's volatile output. Our results indicate that there is a previously unrecognized, relatively heavy isotopic signature to bulk volcanic gas plumes in the Central Andes, which can be attributed to a strong influence from components of the subducting slab, but may also reflect some local crustal contamination. The techniques we describe open new avenues for quantifying the roles that subduction zones and arc volcanoes play in the global carbon cycle.

  8. The ~ 2000 yr BP Jumento volcano, one of the youngest edifices of the Chichinautzin Volcanic Field, Central Mexico

    Science.gov (United States)

    Arce, J. L.; Muñoz-Salinas, E.; Castillo, M.; Salinas, I.

    2015-12-01

    The Chichinautzin Volcanic Field is situated at the southern limit of the Basin of Mexico and the Metropolitan area of Mexico City, the third most populated city around the world. The Chichinautzin Volcanic field holds more than 220 monogenetic volcanoes. Xitle is the youngest of these with an estimated age of 1.6 ky BP. Xitle's eruptive activity took place during the Mesoamerican Mexican Pre-classic period and is related to the destruction of Cuicuilco Archaeological Site, the oldest civilization known in Central Mexico. However, there are still several regional cones that have not been dated. Based on 14C ages, stratigraphic and geomorphologic criteria, we conclude that the Jumento volcano, located to the west of Xitle, is one of the youngest cones of the Chichinautzin Volcanic Field. The Jumento volcano has a basaltic andesite composition, and its eruptive activity was initially hydromagmatic, followed by Strombolian and finally effusive events occurred recorded through: (1) a sequence of hydromagmatic pyroclastic surges and ashfall layers emplaced at a radius of > 5 km from the crater with charcoal fragments at its base; this activity built the Jumento's cone with slopes of 32°; and (2) lava flows that breached the southern part of the cone and flowed for up to 2.5 km from the vent. The resulting 14C ages for this volcano yielded a maximum age of ~ 2 ky BP. Morphometric analysis indicates that the state of degradation of Jumento cone is similar to the Xitle, suggesting that the Jumento could be in the state of degradation of a volcanic structure of similar age or younger adding credence to the probable radiocarbon age of ~ 2 ky BP for the Jumento edifice.

  9. Bromo volcano area as human-environment system: interaction of volcanic eruption, local knowledge, risk perception and adaptation strategy

    Science.gov (United States)

    Bachri, Syamsul; Stötter, Johann; Sartohadi, Junun

    2013-04-01

    People in the Bromo area (located within Tengger Caldera) have learn to live with the threat of volcanic hazard since this volcano is categorized as an active volcano in Indonesia. During 2010, the eruption intensity increased yielding heavy ash fall and glowing rock fragments. A significant risk is also presented by mass movement which reaches areas up to 25 km from the crater. As a result of the 2010 eruption, 12 houses were destroyed, 25 houses collapsed and there were severe also effects on agriculture and the livestock sector. This paper focuses on understanding the interaction of Bromo volcanic eruption processes and their social responses. The specific aims are to 1) identify the 2010 eruption of Bromo 2) examine the human-volcano relationship within Bromo area in general, and 3) investigate the local knowledge related to hazard, risk perception and their adaptation strategies in specific. In-depth interviews with 33 informants from four districts nearest to the crater included local people and authorities were carried out. The survey focused on farmers, key persons (dukun), students and teachers in order to understand how people respond to Bromo eruption. The results show that the eruption in 2010 was unusual as it took continued for nine months, the longest period in Bromo history. The type of eruption was phreatomagmatic producing material dominated by ash to fine sand. This kind of sediment typically belongs to Tengger mountain eruptions which had produced vast explosions in the past. Furthermore, two years after the eruption, the interviewed people explained that local knowledge and their experiences with volcanic activity do not influence their risk perception. Dealing with this eruption, people in the Bromo area applied 'lumbung desa' (traditional saving systems) and mutual aid activity for surviving the volcanic eruption. Keywords: Human-environment system, local knowledge, risk perception, adaptation strategies, Bromo Volcano Indonesia

  10. Volcano Monitoring and Early Warning on MT Etna, Italy, Using Volcanic Tremor - Methods and Technical Aspects

    Science.gov (United States)

    D'Agostino, Marcello; Di Grazia, Giuseppe; Ferrari, Ferruccio; Langer, Horst; Messina, Alfio; Reitano, Danilo; Spampinato, Salvatore

    2013-04-01

    Recent activity on Mt Etna was characterized by 25 lava fountains occurred on Mt Etna in 2011 and the first semester of 2012. In summer 2012 volcanic activity in a milder form was noticed within the Bocca Nuova crater, before it came to an essential halt in August 2012. Together with previous unrests (e. g., in 2007-08) these events offer rich material for testing automatic data processing and alert issue in the context of volcano monitoring. Our presentation focuses on the seismic background radiation - volcanic tremor - which has a key role in the surveillance of Mt Etna. From 2006 on a multi-station alert system exploiting STA/LTA ratios, has been established in the INGV operative centre of Catania. Besides, also the frequency content has been found to change correspondingly to the type of volcanic activity, and can thus be exploited for warning purposes. We apply Self Organizing Maps and Fuzzy Clustering which offer an efficient way to visualize signal characteristics and its development with time. These techniques allow to identify early stages of eruptive events and automatically flag a critical status before this becomes evident in conventional monitoring techniques. Changes of tremor characteristics are related to the position of the source of the signal. Given the dense seismic network we can base the location of the sources on distribution of the amplitudes across the network. The locations proved to be extremely useful for warning throughout both a flank eruption in 2008 as well as the 2011 lava fountains. During all these episodes a clear migration of tremor sources towards the eruptive centres was revealed in advance. The location of the sources completes the picture of an imminent volcanic unrest and corroborates early warnings flagged by the changes of signal characteristics. Automatic real time data processing poses high demands on computational efficiency, robustness of the methods and stability of data acquisition. The amplitude based multi

  11. Petrologic insights into basaltic volcanism at historically active Hawaiian volcanoes: Chapter 6 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Helz, Rosalind L.; Clague, David A.; Sisson, Thomas W.; Thornber, Carl R.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Study of the petrology of Hawaiian volcanoes, in particular the historically active volcanoes on the Island of Hawai‘i, has long been of worldwide scientific interest. When Dr. Thomas A. Jaggar, Jr., established the Hawaiian Volcano Observatory (HVO) in 1912, detailed observations on basaltic activity at Kīlauea and Mauna Loa volcanoes increased dramatically. The period from 1912 to 1958 saw a gradual increase in the collection and analysis of samples from the historical eruptions of Kīlauea and Mauna Loa and development of the concepts needed to evaluate them. In a classic 1955 paper, Howard Powers introduced the concepts of magnesia variation diagrams, to display basaltic compositions, and olivine-control lines, to distinguish between possibly comagmatic and clearly distinct basaltic lineages. In particular, he and others recognized that Kīlauea and Mauna Loa basalts must have different sources.

  12. Integrating science and education during an international, multi-parametric investigation of volcanic activity at Santiaguito volcano, Guatemala

    Science.gov (United States)

    Lavallée, Yan; Johnson, Jeffrey; Andrews, Benjamin; Wolf, Rudiger; Rose, William; Chigna, Gustavo; Pineda, Armand

    2016-04-01

    In January 2016, we held the first scientific/educational Workshops on Volcanoes (WoV). The workshop took place at Santiaguito volcano - the most active volcano in Guatemala. 69 international scientists of all ages participated in this intensive, multi-parametric investigation of the volcanic activity, which included the deployment of seismometers, tiltmeters, infrasound microphones and mini-DOAS as well as optical, thermographic, UV and FTIR cameras around the active vent. These instruments recorded volcanic activity in concert over a period of 3 to 9 days. Here we review the research activities and present some of the spectacular observations made through this interdisciplinary efforts. Observations range from high-resolution drone and IR footage of explosions, monitoring of rock falls and quantification of the erupted mass of different gases and ash, as well as morphological changes in the dome caused by recurring explosions (amongst many other volcanic processes). We will discuss the success of such integrative ventures in furthering science frontiers and developing the next generation of geoscientists.

  13. Environmental hazards of fluoride in volcanic ash: a case study from Ruapehu volcano, New Zealand

    Science.gov (United States)

    Cronin, Shane J.; Neall, V. E.; Lecointre, J. A.; Hedley, M. J.; Loganathan, P.

    2003-03-01

    The vent-hosted hydrothermal system of Ruapehu volcano is normally covered by a c. 10 million m 3 acidic crater lake where volcanic gases accumulate. Through analysis of eruption observations, granulometry, mineralogy and chemistry of volcanic ash from the 1995-1996 Ruapehu eruptions we report on the varying influences on environmental hazards associated with the deposits. All measured parameters are more dependent on the eruptive style than on distance from the vent. Early phreatic and phreatomagmatic eruption phases from crater lakes similar to that on Ruapehu are likely to contain the greatest concentrations of environmentally significant elements, especially sulphur and fluoride. These elements are contained within altered xenolithic material extracted from the hydrothermal system by steam explosions, as well as in residue hydrothermal fluids adsorbed on to particle surfaces. In particular, total F in the ash may be enriched by a factor of 6 relative to original magmatic contents, although immediately soluble F does not show such dramatic increases. Highly soluble NaF and CaSiF 6 phases, demonstrated to be the carriers of 'available' F in purely magmatic eruptive systems, are probably not dominant in the products of phreatomagmatic eruptions through hydrothermal systems. Instead, slowly soluble compounds such as CaF 2, AlF 3 and Ca 5(PO 4) 3F dominate. Fluoride in these phases is released over longer periods, where only one third is leached in a single 24-h water extraction. This implies that estimation of soluble F in such ashes based on a single leach leads to underestimation of the F impact, especially of a potential longer-term environmental hazard. In addition, a large proportion of the total F in the ash is apparently soluble in the digestive system of grazing animals. In the Ruapehu case this led to several thousand sheep deaths from fluorosis.

  14. Evidence of recent deep magmatic activity at Cerro Bravo-Cerro Machín volcanic complex, central Colombia. Implications for future volcanic activity at Nevado del Ruiz, Cerro Machín and other volcanoes

    Science.gov (United States)

    Londono, John Makario

    2016-09-01

    In the last nine years (2007-2015), the Cerro Bravo-Cerro Machín volcanic complex (CBCMVC), located in central Colombia, has experienced many changes in volcanic activity. In particular at Nevado del Ruiz volcano (NRV), Cerro Machin volcano (CMV) and Cerro Bravo (CBV) volcano. The recent activity of NRV, as well as increasing seismic activity at other volcanic centers of the CBCMVC, were preceded by notable changes in various geophysical and geochemical parameters, that suggests renewed magmatic activity is occurring at the volcanic complex. The onset of this activity started with seismicity located west of the volcanic complex, followed by seismicity at CBV and CMV. Later in 2010, strong seismicity was observed at NRV, with two small eruptions in 2012. After that, seismicity has been observed intermittently at other volcanic centers such as Santa Isabel, Cerro España, Paramillo de Santa Rosa, Quindío and Tolima volcanoes, which persists until today. Local deformation was observed from 2007 at NRV, followed by possible regional deformation at various volcanic centers between 2011 and 2013. In 2008, an increase in CO2 and Radon in soil was observed at CBV, followed by a change in helium isotopes at CMV between 2009 and 2011. Moreover, SO2 showed an increase from 2010 at NRV, with values remaining high until the present. These observations suggest that renewed magmatic activity is currently occurring at CBCMVC. NRV shows changes in its activity that may be related to this new magmatic activity. NRV is currently exhibiting the most activity of any volcano in the CBCMVC, which may be due to it being the only open volcanic system at this time. This suggests that over the coming years, there is a high probability of new unrest or an increase in volcanic activity of other volcanoes of the CBCMVC.

  15. Young volcanoes in the Chilean Southern Volcanic Zone: A statistical approach to eruption prediction based on time series

    Science.gov (United States)

    Dzierma, Y.; Wehrmann, H.

    2010-03-01

    Forecasting volcanic activity has long been an aim of applied volcanology with regard to mitigating consequences of volcanic eruptions. Effective disaster management requires both information on expected physical eruption behaviour such as types and magnitudes of eruptions as typical for the individual volcano, usually reconstructed from deposits of past eruptions, and the likelihood that a new eruption will occur within a given time. Here we apply a statistical procedure to provide a probability estimate for future eruptions based on eruption time series, and discuss the limitations of this approach. The statistical investigation encompasses a series of young volcanoes of the Chilean Southern Volcanic Zone. Most of the volcanoes considered have been active in historical times, in addition to several volcanoes with a longer eruption record from Late-Pleistocene to Holocene. Furthermore, eruption rates of neighbouring volcanoes are compared with the aim to reveal possible regional relations, potentially resulting from local to medium-scale tectonic dynamics. One special focus is directed to the two currently most active volcanoes of South America, Llaima and Villarrica, whose eruption records comprise about 50 historical eruptions over the past centuries. These two front volcanoes are considered together with Lanín Volcano, situated in the back-arc of Villarrica, for which the analysis is based on eight eruptions in the past 10 ka. For Llaima and Villarrica, affirmed tests for independence of the repose times between successive eruptions permit to assume Poisson processes; which is hampered for Lanín because of the more limited availability of documented eruptions. The assumption of stationarity reaches varying degrees of confidence depending on the time interval considered, ameliorating towards the more recent and hence probably more complete eruption record. With these pre-requisites of the time series, several distribution functions are fit and the goodness of

  16. Classification of volcanic ash particles from Sakurajima volcano using CCD camera image and cluster analysis

    Science.gov (United States)

    Miwa, T.; Shimano, T.; Nishimura, T.

    2012-12-01

    total luminance=(R+G+B)/665. We classify the volcanic ash particles from the Dendrograms into three groups based on the euclid distance. The groups are named as Group A, B and C in order of increasing of the average value of total luminance. The classification shows that the numbers of particles belonging to Group A, B and C are 77, 25 and 6 in Feb, 09, 2009 sample, and 102, 19 and 6 in Jan, 13, 2010 sample, respectively. The examination under stereoscopic microscope suggests that Group A, B and C mainly correspond with juvenile, altered and free-crystal particles, respectively. So the result of classification by present method demonstrates a difference in the contribution of juvenile material between the two days. To evaluate reliability of our classification, we classify pseudo-samples in which errors of 10% are added in the measured parameters. We apply our method to one thousand psuedo-samples, and the result shows that the numbers of particles classified into the three groups vary less than 20 % of the total number of 235 particles. Our system can classify 120 particles within 6 minutes so that we easily increase the number of ash particles, which enable us to improve reliabilities and resolutions of the classification and to speedily capture temporal changes of the property of ash particles from active volcanoes.

  17. Characteristics of volcanic gas correlated to the eruption activity; Case study in the Merapi Volcano, periods of 1990-1994

    Directory of Open Access Journals (Sweden)

    Priatna Priatna

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol2no4.20074Volcanic gases, collected from Gendol and Woro solfatara fields, the summit of Merapi Volcano during 1990-1994, show an increase in chemical composition of H , CO, CO , SO , and HCl prior to the volcanic events, on the contrary to the drastic decreasing water vapour. The carbon/sulfur ratio of the volcanic gases lies between 1.5 and 5.7 which means that they were derived from the fresh magma. The Apparent Equilibrium Temperature (AET which is calculated from chemical compositions of volcanic gases using reaction of SO +3H = H S+2H O showed an increasing value prior to the volcanic events. The Merapi activities lasted during August 1990 to November 1994 showed a significant increase in ratio SO /H S prior to the November 1994 pyroclastic flow. The isotopic composition of volcanic gas condensates indicates that water vapour in Gendol is directly derived from the fresh magma. On the other hand, the contamination and cooling by the subsurface water occurred around the Woro field at a shallow part. 

  18. Managing the effects of accelerated glacial melting on volcanic collapse and debris flows: Planchon-Peteroa Volcano, Southern Andes

    Science.gov (United States)

    Tormey, Daniel

    2010-11-01

    Glaciated mountains are among the most sensitive environments to climatic changes, and recent work has shown that large-scale glacial melting, including at the end of the Pleistocene, caused a significant increase in the incidence of large volcanic sector collapse and debris flows on then-active volcanoes. With current accelerated rates of glacial melting, glaciated active volcanoes are at an increasing risk of sector collapse, debris flow and landslide. These catastrophic events are Earth's most damaging erosion phenomenon, causing extensive property damage and loss of life. This paper illustrates these effects in well-studied settings, focusing on the end-Pleistocene to Holocene glaciovolcanic growth and destruction of the cone of the active volcano Planchon-Peteroa in the Andean Southern Volcanic Zone at latitude 35° 15' S, along the border between Chile and Argentina. The development of the volcano over the last 14,000 years illustrates how glacial melting and magmatic activity can trigger landslides and sector collapses. Planchon had a large sector collapse that produced a highly mobile and erosive debris avalanche 11,000 years BP, and other slope instabilities during the end-Pleistocene/early Holocene deglaciation. The summit amphitheater left after the sector collapse was subject to alternating periods of glaciation and melting-induced lake formation. Breaching of the moraine dams then formed lahars and landslides originating at the western edge of the summit amphitheater, and the deposits are preserved along the western flank of the volcano. Deep incision of moraine deposits further down the western slope of the volcano indicates that the lahars and landslides were water-rich and had high erosive power. As illustrated by Planchon-Peteroa, the interplay among glacial growth and melting, magmatic activity, and slope stability is complex, but must be accounted for in volcanic hazard assessment. Planchon-Peteroa currently has the southernmost temperate zone

  19. Contrasting carbonatite volcanism at the Kerimasi and Oldoinyo Lengai volcanoes, northern Tanzania

    Science.gov (United States)

    Mattsson, Hannes B.; Bosshard-Stadlin, Sonja A.; Weidendorfer, Daniel; Balashova, Anna

    2014-05-01

    The two neighboring volcanoes, Kerimasi and Oldoinyo Lengai, located 12 km apart in the eastern branch of the East African Rift in northern Tanzania display many similarities but also significant differences in terms of the types of magmas being erupted. The carbonatites of Kerimasi have a rather large compositional span (MgO=0-14 wt.% and CaO=32-56 wt.%). This is in sharp contrast to the very uniform Na-carbonatites typically erupted at Oldoinyo Lengai. As a result of this the Kerimasi carbonatites classify as Ca-carbonatites and they are all virtually devoid of alkalis. The trace elements patterns are rather uniform for the Kerimasi carbonatites and the patterns are similar to Ca-carbonatites found elsewhere. They differ to the natrocarbonatites by having considerable higher Zr and Hf concentrations. The slope of the REE ([La/Yb]N) are considerably flatter for the Kerimasi rocks (12 to 45) in comparison to natrocarbonatites (>1000) or even Ca-carbonatite dykes from Oldoinyo Lengai (~100). Interestingly, the Trig Point Hill debris avalanche deposit of Kerimasi is dominated by carbonatitic material in the form of blocks comprising intrusions, cumulates and vesicular lava flows (calculated to have a total volume of approximately 0.6 to 1.2 km3). This strongly indicates that the collapsed part of volcanic edifice at Kerimasi is in fact dominated by carbonatitic material with only minor amounts of silicate rocks. At Oldoinyo Lengai the carbonatitic material mainly occur inside the summit crater as small lava flows (with a combined volume of collapses but none of the resulting debris avalanche deposits contain lithics of carbonatitic material. This discrepancy is noteworthy, as the location of magma chamber is supposedly shallower at Oldoinyo Lengai (i.e., at a few km depth inside the volcano). Yet none of this is reflected in resulting deposits. Although much has been learned since Barry Dawson's discovery of the magmatic nature of the natrocarbonatites at Oldoinyo

  20. Diffuse volcanic degassing and thermal energy release 2015 surveys from the summit cone of Teide volcano, Tenerife (Canary Islands, Spain)

    Science.gov (United States)

    Melián, Gladys; Asensio-Ramos, María; Padilla, Germán; Alonso, Mar; Halliwell, Simon; Sharp, Emerson; Butters, Damaris; Ingman, Dylan; Alexander, Scott; Cook, Jenny; Pérez, Nemesio M.

    2016-04-01

    The summit cone of Teide volcano (Spain) is characterized by the presence of a weak fumarolic system, steamy ground, and high rates of diffuse CO2 degassing all around this area. The temperature of the fumaroles (83° C) corresponds to the boiling point of water at discharge conditions. Water is the major component of these fumarolic emissions, followed by CO2, N2, H2, H2S, HCl, Ar, CH4, He and CO, a composition typical of hydrothermal fluids. Previous diffuse CO2 surveys have shown to be an important tool to detect early warnings of possible impending volcanic unrests at Tenerife Island (Melián et al., 2012; Pérez et al., 2013). In July 2015, a soil and fumarole gas survey was undertaken in order to estimate the diffuse volcanic degassing and thermal energy release from the summit cone of Teide volcano. A diffuse CO2 emission survey was performed selecting 170 observation sites according to the accumulation chamber method. Soil CO2 efflux values range from non-detectable (˜0.5 g m-2d-1) up to 10,672 g m-2d-1, with an average value of 601 g m-2d-1. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. Measurement of soil CO2 efflux allowed an estimation of 162 ± 14 t d-1 of deep seated derived CO2. To calculate the steam discharge associated with this volcanic/hydrothermal CO2 output, we used the average H2O/CO2 mass ratio equal to 1.19 (range, 0.44-3.42) as a representative value of the H2O/CO2 mass ratios for Teide fumaroles. The resulting estimate of the steam flow associated with the gas flux is equal to 193 t d-1. The condensation of this steam results in a thermal energy release of 5.0×1011J d-1 for Teide volcano or a total heat flow of 6 MWt. The diffuse gas emissions and thermal energy released from the summit of Teide volcano are comparable to those observed at other volcanoes. Sustained surveillance using these methods will be valuable for monitoring the activity of Teide volcano.

  1. Volcanic ash and daily mortality in Sweden after the Icelandic volcano eruption of May 2011.

    Science.gov (United States)

    Oudin, Anna; Carlsen, Hanne K; Forsberg, Bertil; Johansson, Christer

    2013-12-10

    In the aftermath of the Icelandic volcano Grimsvötn's eruption on 21 May 2011, volcanic ash reached Northern Europe. Elevated levels of ambient particles (PM) were registered in mid Sweden. The aim of the present study was to investigate if the Grimsvötn eruption had an effect on mortality in Sweden. Based on PM measurements at 16 sites across Sweden, data were classified into an ash exposed data set (Ash area) and an unexposed data set (No ash area). Data on daily all-cause mortality were obtained from Statistics Sweden for the time period 1 April through 31 July 2011. Mortality ratios were calculated as the ratio between the daily number of deaths in the Ash area and the No ash area. The exposure period was defined as the week following the days with elevated particle concentrations, namely 24 May through 31 May. The control period was defined as 1 April through 23 May and 1 June through 31 July. There was no absolute increase in mortality during the exposure period. However, during the exposure period the mean mortality ratio was 2.42 compared with 2.17 during the control period, implying a relatively higher number of deaths in the Ash area than in the No ash area. The differences in ratios were mostly due to a single day, 31 May, and were not statistically significant when tested with a Mann-Whitney non-parametric test (p > 0.3). The statistical power was low with only 8 days in the exposure period (24 May through 31 May). Assuming that the observed relative differences were not due to chance, the results would imply an increase of 128 deaths during the exposure period 24-31 May. If 31 May was excluded, the number of extra deaths was reduced to 20. The results of the present study are contradicting and inconclusive, but may indicate that all-cause mortality was increased by the ash-fall from the Grimsvötn eruption. Meta-analysis or pooled analysis of data from neighboring countries might make it possible to reach sufficient statistical power to study effects

  2. Long range transport and fate of a stratospheric volcanic cloud from Soufrière Hills volcano, Montserrat

    Directory of Open Access Journals (Sweden)

    A. J. Prata

    2007-10-01

    Full Text Available Volcanic eruptions emit gases, ash particles and hydrometeors into the atmosphere, occasionally reaching heights of 20 km or more, to reside in the stratospheric overworld where they affect the radiative balance of the atmosphere and the Earth's climate. Here we use satellite measurements and a Lagrangian particle dispersion model to determine the mass loadings, vertical penetration, horizontal extent, dispersion and transport of volcanic gases and particles in the stratosphere from the volcanic cloud emitted during the 20 May 2006 eruption of Soufrière Hills volcano, Montserrat, West Indies. Infrared, ultraviolet and microwave radiation measurements from two polar orbiters are used to quantify the gases and particles, and track the movement of the cloud for 23 days, over a distance of ~18 000 km. Approximately, 0.1±0.01 Tg(S was injected into the stratosphere in the form of SO2: the largest single sulphur input to the stratosphere in 2006. Microwave Limb Sounder measurements indicate an enhanced mass of HCl of ~0.003–0.01 Tg. Geosynchronous satellite data reveal the rapid nature of the stratospheric injection and indicate that the eruption cloud contained ~2 Tg of ice, with very little ash reaching the stratosphere. These new satellite measurements of volcanic gases and particles can be used to test the sensitivity of climate to volcanic forcing and assess the impact of stratospheric sulphates on climate cooling.

  3. Structural analysis and thermal remote sensing of the Los Humeros Volcanic Complex: Implications for volcano structure and geothermal exploration

    Science.gov (United States)

    Norini, G.; Groppelli, G.; Sulpizio, R.; Carrasco-Núñez, G.; Dávila-Harris, P.; Pellicioli, C.; Zucca, F.; De Franco, R.

    2015-08-01

    The Los Humeros Volcanic Complex (LHVC) is an important geothermal target in the Trans-Mexican Volcanic Belt. Understanding the structure of the LHVC and its influence on the occurrence of thermal anomalies and hydrothermal fluids is important to get insights into the interplay between the volcano-tectonic setting and the characteristics of the geothermal resources in the area. In this study, we present a structural analysis of the LHVC, focused on Quaternary tectonic and volcano-tectonic features, including the areal distribution of monogenetic volcanic centers. Morphostructural analysis and structural field mapping revealed the geometry, kinematics and dynamics of the structural features in the study area. Also, thermal infrared remote sensing analysis has been applied to the LHVC for the first time, to map the main endogenous thermal anomalies. These data are integrated with newly proposed Unconformity Bounded Stratigraphic Units, to evaluate the implications for the structural behavior of the caldera complex and geothermal field. The LHVC is characterized by a multistage formation, with at least two major episodes of caldera collapse: Los Humeros Caldera (460 ka) and Los Potreros Caldera (100 ka). The study suggests that the geometry of the first collapse recalls a trap-door structure and impinges on a thick volcanic succession (10.5-1.55 Ma), now hosting the geothermal reservoir. The main ring-faults of the two calderas are buried and sealed by the widespread post-calderas volcanic products, and for this reason they probably do not have enough permeability to be the main conveyers of the hydrothermal fluid circulation. An active, previously unrecognized fault system of volcano-tectonic origin has been identified inside the Los Potreros Caldera. This fault system is the main geothermal target, probably originated by active resurgence of the caldera floor. The active fault system defines three distinct structural sectors in the caldera floor, where the

  4. Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption.

    Science.gov (United States)

    Ripepe, Maurizio; Donne, Dario Delle; Genco, Riccardo; Maggio, Giuseppe; Pistolesi, Marco; Marchetti, Emanuele; Lacanna, Giorgio; Ulivieri, Giacomo; Poggi, Pasquale

    2015-05-18

    Effusive eruptions are explained as the mechanism by which volcanoes restore the equilibrium perturbed by magma rising in a chamber deep in the crust. Seismic, ground deformation and topographic measurements are compared with effusion rate during the 2007 Stromboli eruption, drawing an eruptive scenario that shifts our attention from the interior of the crust to the surface. The eruption is modelled as a gravity-driven drainage of magma stored in the volcanic edifice with a minor contribution of magma supplied at a steady rate from a deep reservoir. Here we show that the discharge rate can be predicted by the contraction of the volcano edifice and that the very-long-period seismicity migrates downwards, tracking the residual volume of magma in the shallow reservoir. Gravity-driven magma discharge dynamics explain the initially high discharge rates observed during eruptive crises and greatly influence our ability to predict the evolution of effusive eruptions.

  5. The eruptive history and magmatic evolution of Aluto volcano: new insights into silicic peralkaline volcanism in the Ethiopian rift

    Science.gov (United States)

    Hutchison, William; Pyle, David M.; Mather, Tamsin A.; Yirgu, Gezahegn; Biggs, Juliet; Cohen, Benjamin E.; Barfod, Dan N.; Lewi, Elias

    2016-12-01

    The silicic peralkaline volcanoes of the East African Rift are some of the least studied volcanoes on Earth. Here we bring together new constraints from fieldwork, remote sensing, geochronology and geochemistry to present the first detailed account of the eruptive history of Aluto, a restless silicic volcano located in a densely populated section of the Main Ethiopian Rift. Prior to the growth of the Aluto volcanic complex (before 500 ka) the region was characterized by a significant period of fault development and mafic fissure eruptions. The earliest volcanism at Aluto built up a trachytic complex over 8 km in diameter. Aluto then underwent large-volume ignimbrite eruptions at 316 ± 19 ka and 306 ± 12 ka developing a 42 km2 collapse structure. After a hiatus of 250 ka, a phase of post-caldera volcanism initiated at 55 ± 19 ka and the most recent eruption of Aluto has a radiocarbon age of 0.40 ± 0.05 cal. ka BP. During this post-caldera phase highly-evolved peralkaline rhyolite lavas, ignimbrites and pumice fall deposits have erupted from vents across the complex. Geochemical modelling is consistent with rhyolite genesis from protracted fractionation (> 80%) of basalt that is compositionally similar to rift-related basalts found east of the complex. Based on the style and volume of recent eruptions we suggest that silicic eruptions occur at an average rate of 1 per 1000 years, and that future eruptions of Aluto will involve explosive emplacement of localised pumice cones and effusive obsidian coulees of volumes in the range 1-100 × 106 m3.

  6. Regional radiative impact of volcanic aerosol from the 2009 eruption of Redoubt volcano

    Directory of Open Access Journals (Sweden)

    C. L. Young

    2011-09-01

    Full Text Available High northern latitude eruptions have the potential to release volcanic aerosol into the Arctic environment, perturbing the Arctic's climate system. In this study, we present assessments of shortwave (SW, longwave (LW and net direct aerosol radiative forcings (DARFs and atmospheric heating/cooling rates caused by volcanic aerosol from the 2009 eruption of Redoubt Volcano by performing radiative transfer modeling constrained by NASA A-Train satellite data. The Ozone Monitoring Instrument (OMI, the Moderate Resolution Imaging Spectroradiometer (MODIS, and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT model for volcanic ash were used to characterize aerosol across the region. A representative range of aerosol optical depths (AODs at 550 nm were obtained from MODIS, and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO was used to determine the altitude and thickness of the plumes. The optical properties of volcanic aerosol were calculated using a compositionally resolved microphysical model developed for both ash and sulfates. Two compositions of volcanic aerosol were considered in order to examine a fresh, ash rich plume and an older, ash poor plume. Optical models were incorporated into a modified version of the Santa Barbara Disort Atmospheric Radiative Transfer (SBDART model. Radiative transfer calculations were made for a range of surface albedos and solar zenith angles (SZA representative of the region. We find that the total DARF caused by a fresh, thin plume (~2.5–7 km at an AOD (550 nm range of 0.16–0.58 and SZA = 55° is –46 W m−2AOD−1 at the top of the atmosphere (TOA, 110 W m−2AOD−1 in the aerosol layer, and – 150 W m−2AOD−1 at the surface over seawater. However, the total DARF for the same plume over snow and at the same SZA at TOA, in the layer, and at the surface is 170, 170, and −2 W m−2

  7. Eruption time series statistically examined: Probabilities of future eruptions at Villarrica and Llaima Volcanoes, Southern Volcanic Zone, Chile

    Science.gov (United States)

    Dzierma, Yvonne; Wehrmann, Heidi

    2010-06-01

    Probabilistic forecasting of volcanic eruptions is a central issue of applied volcanology with regard to mitigating consequences of volcanic hazards. Recent years have seen great advances in the techniques of statistical analysis of volcanic eruption time series, which constitutes an essential component of a multi-discipline volcanic hazard assessment. Here, two of the currently most active volcanoes of South America, Villarrica and Llaima, are subjected to an established statistical procedure, with the aim to provide predictions for the likelihood of future eruptions within a given time interval. In the eruptive history of both Villarrica and Llaima Volcanoes, time independence of eruptions provides consistency with Poissonian behaviour. A moving-average test, helping to assess whether the distribution of repose times between eruptions changes in response to the time interval considered, validates stationarity for at least the younger eruption record. For the earlier time period, stationarity is not entirely confirmed, which may artificially result from incompleteness of the eruption record, but can also reveal fluctuations in the eruptive regime. To take both possibilities into account, several different distribution functions are fit to the eruption time series, and the fits are evaluated for their quality and compared. The exponential, Weibull and log-logistic distributions are shown to fit the repose times sufficiently well. The probability of future eruptions within defined time periods is therefore estimated from all three distribution functions, as well as from a mixture of exponential distribution (MOED) for the different eruption regimes and from a Bayesian approach. Both the MOED and Bayesian estimates intrinsically predict lower eruption probabilities than the exponential distribution function, while the Weibull distributions have increasing hazard rates, hence giving the highest eruption probability forecasts. This study provides one of the first

  8. Volcano-tectonic framework of a linear volcanic ridge (Faial-Pico ridge, Azores Archipelago) assessed by paleomagnetic studies

    Science.gov (United States)

    Silva, Pedro; Henry, Bernard; Lopes, Ana; Marques, Fernando; Madureira, Pedro; Hildenbrand, Anthony; Madeira, José; Nunes, João; Roxerová, Zuzana

    2016-04-01

    The morphology of volcanic oceanic islands results from the alternation between constructive and destructive episodes. In this study directional analyses obtained from paleomagnetic studies are used as a tool to achieve relative rotations related with destructive processes intra the Pico-Faial linear volcanic ridge (Azores archipelago; North Atlantic). A total of 45 lava flows and one dyke were sampled preferable along lava piles though to record volcano-tectonic movements. The respective paleomagnetic results are able to show important rotations within the two islands that resemble the onshore signature of this ridge. Paleomagnetic directions retrieved here mostly show elliptical distribution of ChRM's sub-perpendicular to volcanic ridge. Such distribution agrees with the development of listric faults plunging towards the axis of the volcanic ridge at Faial Island and towards offshore at the Topo complex of Pico Island. In Faial Island, the "collapse" related to the magma chamber decompression was accommodated by brittle deformation with listric faults plunging toward the core of the formed graben. On Pico Island, this collapse was probably of less importance and simply accommodated by a local tilting. Listric faults then should have been developed, in the opposite direction (compared to Faial Island case) relatively to the collapsed area, to compensate a relative local uplift. Accordingly paleomagnetic studies appear as key data to retrieve intra-islands deformations due to the volcano-tectonic balance responsible for the construction and destruction of such unstable buildings. This important tool to address georisks and natural hazards remains poorly explored and need to be strongly developed. The author wish to acknowledge MEGAHAZARDS (PTDC/CTE-GIX/108149/2008) and REGENA (PTDC/GEO-FIQ/3648/2012) projects for its major contribution without which this work wouldn't be possible. Publication supported by project FCT UID/GEO/50019/2013 - Instituto Dom Luiz.

  9. Volcanic gas composition changes during the gradual decrease of the gigantic degassing activity of Miyakejima volcano, Japan, 2000-2015

    Science.gov (United States)

    Shinohara, Hiroshi; Geshi, Nobuo; Matsushima, Nobuo; Saito, Genji; Kazahaya, Ryunosuke

    2017-02-01

    The composition of volcanic gases discharged from Miyakejima volcano has been monitored during the intensive degassing activity that began after the eruption in 2000. During the 15 years from 2000 to 2015, Miyakejima volcano discharged 25.5 Mt of SO2, which required degassing of 3 km3 of basaltic magma. The SO2 emission rate peaked at 50 kt/day at the end of 2000 and quickly decreased to 5 kt/day by 2003. During the early degassing period, the volcanic gas composition was constant with the CO2/SO2 = 0.8 (mol ratio), H2O/SO2 = 35, HCl/SO2 = 0.08, and SO2/H2S = 15. The SO2 emission rate decreased gradually to 0.5 kt/day by 2012, and the gas composition also changed gradually to CO2/SO2 = 1.5, H2O/SO2 = 150, HCl/SO2 = 0.15, and SO2/H2S = 6. The compositional changes are not likely caused by changes in degassing pressure or volatile heterogeneity of a magma chamber but are likely attributed to an increase of hydrothermal scrubbing caused by large decrease of the volcanic gas emission rate, suggesting a supply of gases with constant composition during the 15 years. The intensive degassing was modeled based on degassing of a convecting magma conduit. The gradual SO2 emission rate that decrease without changes in volcanic gas composition is attributed to a reduction of diameter of the convecting magma conduit.

  10. Temporal changes in thermal waters related to volcanic activity of Tokachidake Volcano, Japan: implications for forecasting future eruptions

    Science.gov (United States)

    Takahashi, Ryo; Shibata, Tomo; Murayama, Yasuji; Ogino, Tagiru; Okazaki, Noritoshi

    2015-01-01

    In order to detect changes in volcanic activity of Tokachidake Volcano, Japan, we have continuously monitored thermal waters discharging at the western to southwestern flank of the volcano since 1986. The steam-heated waters in the Nukkakushi crater discharged with boiling temperature until 2002. Thermal waters at the Tokachidake spa area have similar compositions to fumarolic gas emitted from the summit craters, indicating that the waters formed by absorption of volcanic gas into shallow aquifers. Thermal waters at the Fukiage spa area were derived from the same aquifer as the Tokachidake spa area until early 1986. However, after that time, NaCl-type thermal water entered the Fukiage spa area during the increase in volcanic activity associated with the 1988-1989 eruption, thus leading to a clear increase in Cl concentrations and temperature. After the eruption, the supply of the NaCl-type thermal water was halted, and the Cl concentrations of the thermal waters decreased. In contrast, SO4 concentrations gradually increased in the Fukiage spa area after 1989, and the temperature has been maintained. These observations indicate that SO4-rich thermal water with a relatively high temperature entered the system instead of the NaCl-type thermal water. As was the case for the 1988-1989 eruption, the Cl concentrations at the Fukiage spa area increased in 2012 during an increase in volcanic activity, implying that the supply of the NaCl-type thermal water had resumed. However, the chemical changes in the thermal waters since 2012 are small compared with those before the 1988-1989 eruption, with oxygen and hydrogen isotopic compositions remaining nearly the same as those of meteoric waters.

  11. Volcanic Lake System at Aso Volcano, Japan: Fluctuations in the Supply of Volcanic Fluid from the Hydrothermal System beneath the Crater Lake (Invited)

    Science.gov (United States)

    Terada, A.; Hashimoto, T.; Kagiyama, T.

    2010-12-01

    Hot crater lakes that develop upon active volcanoes generally overlie the magma-hydrothermal system. At hot crater lakes, most of the thermal energy and mass injected into the lake bottom is trapped in the lake water. It is therefore possible to detect even slight changes in subaqueous geothermal activity. The 1st crater of Nakadake, Aso volcano, Japan, contains a hot crater lake, locally called Yudamari, which is about 200 m in diameter. During a recent calm period, water temperature is around 60-70 °C, and heat discharge from lake surface is approximately constant at 200-300 MW. Historical documents report that Yudamari has repeatedly appeared and disappeared over the past 1,500 years. Changes in water level and temperature suggest that the state of Yudamari is related to volcanic activity, as also reported for Poás in Costa Rica and for Ruapehu in New Zealand. These changes in lake water are probably caused by changes in the input of volcanic fluid to the crater bottom. Therefore, precise observations and analysis of a hot crater lake would reveal the nature of variations in the input of volcanic fluid that originated from the underlying hydrothermal system. However, direct monitoring of the lake water at Yudamari is made difficult by the steep topography and high concentrations of SO2 gas. The recent compilation of a 1-mesh digital surface model (DSM) and installation of a commercial digital camera enabled precise and continuous monitoring of water level with an average accuracy of 10-20 cm. As a result we observed characteristic patterns of change in lake level that show no direct correlation with precipitation, suggesting fluctuations in the supply of volcanic fluid to lake water. To estimate temporal variations in flux and enthalpy from the lake bottom, we developed a numerical model of a hot crater lake applied to the precise observation data for the period from July 2006 to January 2009. The analyses revealed seasonal changes in mass flux (66-132 kg

  12. Measurements of radon and chemical elements: Popocatepetl volcano; Mediciones de radon y elementos quimicos: Volcan Popocatepetl

    Energy Technology Data Exchange (ETDEWEB)

    Pena, P.; Segovia, N.; Lopez, B.; Reyes, A.V. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Armienta, M.A.; Valdes, C.; Mena, M. [IGFUNAM, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Seidel, J.L.; Monnin, M. [UMR 5569 CNRS Hydrosciences, Montpellier (France)

    2002-07-01

    The Popocatepetl volcano is a higher risk volcano located at 60 Km from Mexico City. Radon measurements on soil in two fixed seasons located in the north slope of volcano were carried out. Moreover the radon content, major chemical elements and tracks in water samples of three springs was studied. The radon of soil was determined with solid detectors of nuclear tracks (DSTN). The radon in subterranean water was evaluated through the liquid scintillation method and it was corroborated with an Alpha Guard equipment. The major chemical elements were determined with conventional chemical methods and the track elements were measured using an Icp-Ms equipment. The radon on soil levels were lower, indicating a moderate diffusion of the gas across the slope of the volcano. The radon in subterranean water shown few changes in relation with the active scene of the volcano. The major chemical elements and tracks showed a stable behavior during the sampling period. (Author)

  13. Science at the policy interface: volcano-monitoring technologies and volcanic hazard management

    Science.gov (United States)

    Donovan, Amy; Oppenheimer, Clive; Bravo, Michael

    2012-07-01

    This paper discusses results from a survey of volcanologists carried out on the Volcano Listserv during late 2008 and early 2009. In particular, it examines the status of volcano monitoring technologies and their relative perceived value at persistently and potentially active volcanoes. It also examines the role of different types of knowledge in hazard assessment on active volcanoes, as reported by scientists engaged in this area, and interviewees with experience from the current eruption on Montserrat. Conclusions are drawn about the current state of monitoring and the likely future research directions, and also about the roles of expertise and experience in risk assessment on active volcanoes; while local knowledge is important, it must be balanced with fresh ideas and expertise in a combination of disciplines to produce an advisory context that is conducive to high-level scientific discussion.

  14. How to associate with volcanoes. Mitigation of volcanic hazards; Kazan tono tsukiaikata. Kazan saigai wo doyatte herasuka

    Energy Technology Data Exchange (ETDEWEB)

    Kawabe, Y. [Geological Survey of Japan, Tsukuba (Japan)

    1997-08-01

    This paper describes how to deal with volcanic hazards. Basaltic lave such as in the Kilauea volcano flows quickly, while andesite lava such as in Mt. Asama and Mt. Sakurajima in Japan flows slowly. The pyroclastic flow in the Unzen area was a flow of high-temperature lava, pumice stones and gas driven to a high speed by gravity. The flow is so dangerous as it flows so quickly as allowing no time to escape from. Pyroclastic fall-outs and volcanic gases also give damages of different forms. Mountain collapse and debris avalanche in which a volcanic mountain collapses by eruption and earthquake acting as a trigger can also cause a large disaster. A debris flow may also do the same. Knowing the history of volcanic activities by making geological surveys may help judge what type of eruptive activities is prone to occur. On the other hand, the current conditions must be kept observed by performing seismic observations. Eruption itself, a large-scale lava flow and a pyroclastic flow cannot be prevented by using any hardware technique. Software measures are important to utilize more adequately areas and soil natures with high risks. The National Land Agency has prepared recently a guideline for making hazard prediction maps. It is important that both the administration and general residents utilize this guideline. 11 refs., 3 figs., 3 tabs.

  15. Acute health effects associated with exposure to volcanic air pollution (vog) from increased activity at Kilauea Volcano in 2008.

    Science.gov (United States)

    Longo, Bernadette M; Yang, Wei; Green, Joshua B; Crosby, Frederick L; Crosby, Vickie L

    2010-01-01

    In 2008, the Kilauea Volcano on the island of Hawai'i increased eruption activity and emissions of sulfurous volcanic air pollution called vog. The purpose of this study was to promptly assess for a relative increase in cases of medically diagnosed acute illnesses in an exposed Hawaiian community. Using a within-clinic retrospective cohort design, comparisons were made for visits of acute illnesses during the 14 wk prior to the increased volcanic emissions (low exposure) to 14 wk of high vog exposure when ambient sulfur dioxide was threefold higher and averaged 75 parts per billion volume per day. Logistic regression analysis estimated effect measures between the low- and high-exposure cohorts for age, gender, race, and smoking status. There were statistically significant positive associations between high vog exposure and visits for medically diagnosed cough, headache, acute pharyngitis, and acute airway problems. More than a sixfold increase in odds was estimated for visits with acute airway problems, primarily experienced by young Pacific Islanders. These findings suggest that the elevated volcanic emissions in 2008 were associated with increased morbidity of acute illnesses in age and racial subgroups of the general Hawaiian population. Continued investigation is crucial to fully assess the health impact of this natural source of sulfurous air pollution. Culturally appropriate primary- and secondary-level health prevention initiatives are recommended for populations in Hawai'i and volcanically active areas worldwide.

  16. History of Red Crater volcano, Tongariro Volcanic Centre (New Zealand): Abrupt shift in magmatism following recharge and contrasting evolution between neighboring volcanoes

    Science.gov (United States)

    Shane, Phil; Maas, Roland; Lindsay, Jan

    2017-06-01

    Red Crater volcano is one of several contemporaneously active vents on the Tongariro Volcanic Centre. Its history provides an opportunity to investigate the contrasting magmatic evolutionary paths of closely-spaced volcanoes. Rocks erupted at Red Crater over the last 3.4 ka display typical subduction-related trace element and isotopic signatures. Those erupted pre-1.8 ka are medium-K andesites (SiO2 59-62 wt%). They represent the most voluminous magmas and were emplaced in 5 lava flow events. An abrupt shift to the eruption of basaltic andesite (SiO2 53-54 wt%) with less radiogenic Sr-Nd-Pb isotope ratios, occurred post-1.8 ka. This period comprised 6 smaller volume, lava flow episodes and the contemporaneous development of a scoria cone. Plagioclase phenocrysts in post-1.8 ka lava flows have resorbed cores with diverse textural and compositional growth patterns, as would be expected from the disruption of a crystal mush. They are similar to phenocrysts of the pre-1.8 ka lava flows. The post-1.8 ka plagioclase is distinguished from those in the older lavas by overgrowths with elevated An ( 70-90), FeO and MgO contents, that mantle the resorbed cores ( An50-70). These rims are compositionally similar to groundmass plagioclase. This demonstrates that new mafic magma was intruded into the system, mixing with and entraining relic crystals from the older andesite system. Iron and Mg zoning patterns in the crystals are not consistent with significant re-equilibration via diffusion. Hence, the generation of eruptible magma during the last 1.8 ka required repeated mafic intrusion events. The emptying of the older andesitic magma reservoir early in the volcano's history removed buoyancy barriers to the direct eruption of more mafic magmas. This pattern of magmatism is not recorded at the contemporaneously active Ngauruhoe volcano, just 3 km to the SSW. Ngauruhoe rocks are compositionally distinct and are more heterogeneous in isotopic composition. Although mafic recharge is

  17. Impact of volcanic processes on the cryospheric system of the Peteroa Volcano, Andes of southern Mendoza, Argentina

    Science.gov (United States)

    Liaudat, Dario Trombotto; Penas, Pablo; Aloy, Gustavo

    2014-03-01

    Soil temperatures of the active Volcanic Complex Peteroa situated in the Cordillera Principal between Chile and Argentina at 35°15‧ S and 70°35‧ W (approximately) were monitored in the area, and local geomorphology (periglacial geomorphology, presence of permafrost, and cryoforms) was studied. The present contribution also resulted in a comparison of two consecutive analyses of the volcano peak carried out with special thermocameras (AGEMA TVH 550, FUR P660) in order to study the thermal range of different hot and cold sites selected in 2009. The thermocameras were used ascending by foot and also during flights with a Cessna 180. A night expedition to the volcanic avalanche caldera, at up to 3900 m asl (approximately), completed the monitoring activity of 2010. Hot zones were associated to present volcanism and cold zones to the presence of glacier ice and shadowy slopes with possible presence of permafrost. Identifying and mapping uncovered and covered ice was possible with the help of monitoring and geomorphological interpretation related to the upper englacement, which is severely affected by volcanism. Glaciers are retreating toward the north or approaching the rims of the volcanic avalanche caldera leaving islands of ice associated with superficial permafrost. The cryogenic area with slope permafrost was identified through active protalus and sedimentary cryogenic slopes. Craters have undergone considerable thermal changes in comparison to the year 2009; and new, much more vigorous fumaroles have appeared in hot areas detected in 2009 following a tendency toward the west. New subaquatic heat columns that appeared in crater 3, crater walls, and glaciated areas vanished, supplying cold water and thus contributing to the formation of a new lake in crater 4. A possible post-seismic shift of the volcanic activity may provide geodynamical evidence of the changes registered in other areas after the earthquake of 27 February 2010.

  18. Isotopic composition of Pb and Th in interplinian volcanics from Somma-Vesuvius volcano, Italy

    Science.gov (United States)

    Cortini, M.; Ayuso, R.A.; de Vivo, B.; Holden, P.; Somma, R.

    2004-01-01

    We present a detailed isotopic study of volcanic rocks emitted from Somma-Vesuvius volcano during three periods of interplinian activity: "Protohistoric" (3550 y B.P. to 79 A.D.), "Ancient Historic" (79 to 472 A.D.) and "Medieval" (472 to 1631 A.D.). Pb isotopic compositions of two acid leached fractions and whole rock residues of 37 whole rock samples (determined by Somma et al., 2001) show that each of the three interplinian periods is distinguished by small, systematic, and unique uranogenic and thorogenic Pb isotopic trends. This key and novel feature is compatible with the notion that the Pb isotopic data reflect small-scale source heterogeneity operating over relatively short periods of time. From this representative group of samples, a selected set of nine whole rocks were analysed for Th isotopes. 232Th/238U ratios in the source can be obtained independently from Pb and from Th isotopes. Those obtained from Pb isotopes represent source ratios, time-integrated over the whole age of the Earth; they range from 3.9 to 4.1. 232Th/238U obtained from Th isotopes are those of the present source. They are lower, and cluster around 3.5; this difference probably indicates recent U enrichment of the present source. The behaviour of Pb, as inferred by its isotopic ratios, is quite distinct from that of Sr and Nd isotopes: Pb isotope variations are not correlated to Sr or Nd isotope variations. The isotopic contrast is compatible with the idea that the isotopes were decoupled during magmatic production, evolution, and ascent through the crust. Thus, the Pb isotopes do not reflect the effects of the same processes as in the case of the Sr and Nd isotopes, or, as we also favor, they do not necessarily reflect the same source contributions into the magmas. Moreover, the Pb isotopic evolution of the interplinian rocks chiefly reflects mixing, driven by processes that are superimposed on, and independent of, other source contributions that determine the isotopic compositions

  19. Volcanoes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the past thousand years,volcanoes have claimed more than 300,000 lives. Volcanology is ayoung and dangerous science that helps us against the power of the Earth itself.We live on a fiery planet. Nearly 2000 miles beneath our feet, the Earth's inner core reachestemperatures of 12,000 degrees Fahrenheit. Molten rock or magma, rises to the earth's surface. Acold, rigid crust fractured into some twenty plates. When magma breaks through crust it becomes

  20. Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management (G-EVER) project and a next-generation real-time volcano hazard assessment system

    Science.gov (United States)

    Takarada, S.

    2012-12-01

    The first Workshop of Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management (G-EVER1) was held in Tsukuba, Ibaraki Prefecture, Japan from February 23 to 24, 2012. The workshop focused on the formulation of strategies to reduce the risks of disasters worldwide caused by the occurrence of earthquakes, tsunamis, and volcanic eruptions. More than 150 participants attended the workshop. During the workshop, the G-EVER1 accord was approved by the participants. The Accord consists of 10 recommendations like enhancing collaboration, sharing of resources, and making information about the risks of earthquakes and volcanic eruptions freely available and understandable. The G-EVER Hub website (http://g-ever.org) was established to promote the exchange of information and knowledge among the Asia-Pacific countries. Several G-EVER Working Groups and Task Forces were proposed. One of the working groups was tasked to make the next-generation real-time volcano hazard assessment system. The next-generation volcano hazard assessment system is useful for volcanic eruption prediction, risk assessment, and evacuation at various eruption stages. The assessment system is planned to be developed based on volcanic eruption scenario datasets, volcanic eruption database, and numerical simulations. Defining volcanic eruption scenarios based on precursor phenomena leading up to major eruptions of active volcanoes is quite important for the future prediction of volcanic eruptions. Compiling volcanic eruption scenarios after a major eruption is also important. A high quality volcanic eruption database, which contains compilations of eruption dates, volumes, and styles, is important for the next-generation volcano hazard assessment system. The volcanic eruption database is developed based on past eruption results, which only represent a subset of possible future scenarios. Hence, different distributions from the previous deposits are mainly observed due to the differences in

  1. Understanding causality and uncertainty in volcanic observations: An example of forecasting eruptive activity on Soufrière Hills Volcano, Montserrat

    Science.gov (United States)

    Sheldrake, T. E.; Aspinall, W. P.; Odbert, H. M.; Wadge, G.; Sparks, R. S. J.

    2017-07-01

    Following a cessation in eruptive activity it is important to understand how a volcano will behave in the future and when it may next erupt. Such an assessment can be based on the volcano's long-term pattern of behaviour and insights into its current state via monitoring observations. We present a Bayesian network that integrates these two strands of evidence to forecast future eruptive scenarios using expert elicitation. The Bayesian approach provides a framework to quantify the magmatic causes in terms of volcanic effects (i.e., eruption and unrest). In October 2013, an expert elicitation was performed to populate a Bayesian network designed to help forecast future eruptive (in-)activity at Soufrière Hills Volcano. The Bayesian network was devised to assess the state of the shallow magmatic system, as a means to forecast the future eruptive activity in the context of the long-term behaviour at similar dome-building volcanoes. The findings highlight coherence amongst experts when interpreting the current behaviour of the volcano, but reveal considerable ambiguity when relating this to longer patterns of volcanism at dome-building volcanoes, as a class. By asking questions in terms of magmatic causes, the Bayesian approach highlights the importance of using short-term unrest indicators from monitoring data as evidence in long-term forecasts at volcanoes. Furthermore, it highlights potential biases in the judgements of volcanologists and identifies sources of uncertainty in terms of magmatic causes rather than scenario-based outcomes.

  2. Volcanic magma reservoir imaged as a low-density body beneath Aso volcano that terminated the 2016 Kumamoto earthquake rupture

    Science.gov (United States)

    Miyakawa, Ayumu; Sumita, Tatsuya; Okubo, Yasukuni; Okuwaki, Ryo; Otsubo, Makoto; Uesawa, Shimpei; Yagi, Yuji

    2016-12-01

    We resolve the density structure of a possible magma reservoir beneath Aso, an active volcano on Kyushu Island, Japan, by inverting gravity data. In the context of the resolved structure, we discuss the relationship between the fault rupture of the 2016 Kumamoto earthquake and Aso volcano. Low-density bodies were resolved beneath central Aso volcano using a three-dimensional inversion with an assumed density contrast of ±0.3 g/cm3. The resultant location of the southern low-density body is consistent with a magma reservoir reported in previous studies. No Kumamoto aftershocks occur in the southern low-density body; this aseismic anomaly may indicate a ductile feature due to high temperatures and/or the presence of partial melt. Comparisons of the location of the southern low-density body with rupture models of the mainshock, obtained from teleseismic waveform and InSAR data, suggest that the rupture terminus overlaps the southern low-density body. The ductile features of a magma reservoir could have terminated rupture propagation. On the other hand, a northern low-density body is resolved in the Asodani area, where evidence of current volcanic activity is scarce and aftershock activity is high. The northern low-density body might, therefore, be derived from a thick caldera fill in the Asodani area, or correspond to mush magma or a high-crystallinity magma reservoir that could be the remnant of an ancient intrusion.[Figure not available: see fulltext.

  3. Volcanic Risk Perception in Five Communities Located near the Chichón Volcano, Northern Chiapas, Mexico

    Science.gov (United States)

    Rodriguez, F.; Novelo-Casanova, D. A.

    2010-12-01

    The Chichón volcano (17° 19’ N and 93° 15’ W) is located in the state of Chiapas, Mexico. This volcano is classified by UNESCO as one of the ten most dangerous volcanos in the world. The eruptions of March and April in 1982 affected at least 51 communities located in the surroundings of the volcano and caused the death of about 2000 people. In this work we evaluate the risk perception in five communities highly populated: Juárez, Ostuacán, Pichucalco, Reforma and Sunuapa. We selected these communities because they have a high possibility to be affected by a volcanic eruption in the future. Our survey was carried out during February and March 2006. A total of 222 families were interviewed using a questionnaire to measure risk perception. These questionnaires retrieved general information as how long people had been living there and their reasons to do so; their experiences during the 1982 events, their opinion about the authorities participation and their perception of volcanic risk; the plans of the community for disaster prevention and mitigation. Some of the most important results are: (1). People perceive a very low volcanic risk and the 70% of interviewees believe that a new eruption in the future is almost improbable because it happened in 1982. This result is particularly interesting because, according to the state government, more than 100,000 inhabitants will be directly affected in case of a new similar eruption; (2). About 95% of the population do not know the current activity of the volcano and consider that the authorities do not inform properly to their communities; (3). The response of the authorities during the events of 1982 was ranked as deficient mainly because they were unable provide shelters, storage facilities, food as well as medicine and health care access; (4). Approximately 60% of the community will accept to be re-located again in case of a new eruption; (5). About 70% of the population will not accept to be re-located because

  4. Volcanic Hazard Map as a Tool of City Planning: Experiences at Galeras Volcano and the county of Pasto, Colombia.

    Science.gov (United States)

    Calvache, M. L.

    2001-12-01

    Large populated areas located near active volcanoes emphasize the importance to take effective actions towards risk reduction. A volcanic hazard map is believed to be the first step in order to inform government officials, private institutions and community about the danger that poses a particular volcano. The hazard map is a tool that must be used to evaluate risk and elaborate risk map. The risk map must be used by decision makers to take measurements about the land-use accordingly with the hazard present in the area and to prepare contingency plans. In 1998 and 1999 the Colombian government pass a law, where every county of the country has to have a plan of land-use and development (POT) for the following 10 years. The POT must consider natural hazard and risk such as seismicity, landslide and volcanic activity. Without the plan, the county will not receive any economical support from the central government. In the county of Pasto, the largest city in the influence zone of Galeras volcano, the hazard map has been used to promote educational plan in schools, increasing public awareness of Galeras and its hazard, advise and persuade decision makers to consider Galeras hazard in the city development plans. On the other hand, the hazard map has been mistaken as a risk map and it has originated opposition due to the measurements taken as a consequence of the map. This presentation deal with the gain experience of using the hazard map as a tool of information and planing and the confrontation that any decision implies with political, social and economic interest.

  5. Volcanic emissions of metals and halogens from White Island (New Zealand) and Erebus volcano (Antarctica) determined with chemical traps

    Science.gov (United States)

    Wardell, L. J.; Kyle, P. R.; Counce, D.

    2008-11-01

    Volcanic emission rates of As, Sb, Pb, Hg, Se, Cl, and F were determined at Erebus volcano, Antarctica and White Island, New Zealand, using chemical traps. The trace metal fluxes were determined by combining the species to S ratios in the solutions with SO 2 emission rates measured by correlation spectrometry at the two volcanoes. At Erebus volcano, fluxes for the metals Pb and Hg were 2.0 × 10 - 4 and 8.1 × 10 - 6 kg s - 11 , respectively. Fluxes for Cl, F, As, Sb and Se (0.35, 0.15, 2.5 × 10 - 4 , 1.2 × 10 - 5 , and 4.5 × 10 - 6 kg s - 1 , respectively) agreed within error limits for values determined previously by the LiOH impregnated filter method [Zreda-Gostynska, G., Kyle, P., Finnegan, D., Prestbo, K., 1997. Volcanic gas emissions from Mount Erebus and their impact on the Antarctic environment. Journal of Geophysical Research, 102(B7): 15039-15055.], demonstrating the utility of the chemical trap method. A fall in the As/S ratio from 7 × 10 - 4 in 1997/1999 to 3 × 10 - 4 in 2000 at Erebus coincided with a change in the frequency and style of eruptive activity that may have been due to injection of magma into the system. At White Island, chemical trap data indicated fluxes of Cl = 0.90, F = 0.0079, Pb = 2.7 × 10 - 4 , Hg = 1.1 × 10 - 5 , As = 1.3 × 10 - 4 , Sb = 1.9 × 10 - 5 and Se = 1.5 × 10 - 5 kg s - 1 . Samples collected 600 m downwind of the active crater were comparable to samples collected adjacent to the main gas vent, showing that this method can still be used at some distance from a degassing vent.

  6. Chronic exposure to volcanic air pollution and DNA damage in Furnas Volcano (São Miguel Island, Azores, Portugal) inhabitants

    Science.gov (United States)

    Linhares, Diana; Garcia, Patricia; Silva, Catarina; Ferreira, Teresa; Barroso, Joana; Camarinho, Ricardo; Rodrigues, Armindo

    2015-04-01

    Many studies in volcanic air pollution only have in consideration the acute toxic effects of gas or ash releases however the impact of chronic exposure to ground gas emissions in human health is yet poorly known. In the Azores archipelago (Portugal), São Miguel island has one of the most active and dangerous volcanoes: Furnas Volcano. Highly active fumarolic fields, hot springs and soil diffuse degassing phenomena are the main secondary volcanic phenomena that can be seen at the volcano surroundings. One of the main gases released in these diffuse degassing areas is radon (222Rn), which decay results in solid particles that readily settle within the airways. These decay particles emit alpha radiation that is capable of causing severe DNA damage that cumulatively can eventually cause cancer. Previous studies have established that chronic exposure to chromosome-damaging agents can lead to the formation of nuclear anomalies, such as micronuclei that is used for monitoring DNA damage in human populations. The present study was designed to evaluate whether chronic exposure to volcanic air pollution, associated to 222Rn, might result in DNA damage in human oral epithelial cells. A cross sectional study was performed in a study group of 142 individuals inhabiting an area where volcanic activity is marked by active fumarolic fields and soil degassing (hydrothermal area), and a reference group of 368 individuals inhabiting an area without these secondary manifestations of volcanism (non-hydrothermal area). For each individual, 1000 buccal epithelial cells were analyzed for the frequency of micronucleated cells (MNc) and the frequency of cells with other nuclear anomalies (ONA: pyknosis, karyolysis and karyorrhexis), by using the micronucleus assay. Information on lifestyle factors and an informed consent were obtained from each participant. Assessment of indoor radon was performed with the use of radon detectors. Data were analyzed with logistic regression models, adjusted

  7. Long-term autonomous volcanic gas monitoring with Multi-GAS at Mount St. Helens, Washington, and Augustine Volcano, Alaska

    Science.gov (United States)

    Kelly, P. J.; Ketner, D. M.; Kern, C.; Lahusen, R. G.; Lockett, C.; Parker, T.; Paskievitch, J.; Pauk, B.; Rinehart, A.; Werner, C. A.

    2015-12-01

    In recent years, the USGS Volcano Hazards Program has worked to implement continuous real-time in situ volcanic gas monitoring at volcanoes in the Cascade Range and Alaska. The main goal of this ongoing effort is to better link the compositions of volcanic gases to other real-time monitoring data, such as seismicity and deformation, in order to improve baseline monitoring and early detection of volcanic unrest. Due to the remote and difficult-to-access nature of volcanic-gas monitoring sites in the Cascades and Alaska, we developed Multi-GAS instruments that can operate unattended for long periods of time with minimal direct maintenance from field personnel. Our Multi-GAS stations measure H2O, CO2, SO2, and H2S gas concentrations, are comprised entirely of commercial off-the-shelf components, and are powered by small solar energy systems. One notable feature of our Multi-GAS stations is that they include a unique capability to perform automated CO2, SO2, and H2S sensor verifications using portable gas standards while deployed in the field, thereby allowing for rigorous tracking of sensor performances. In addition, we have developed novel onboard data-processing routines that allow diagnostic and monitoring data - including gas ratios (e.g. CO2/SO2) - to be streamed in real time to internal observatory and public web pages without user input. Here we present over one year of continuous data from a permanent Multi-GAS station installed in August 2014 in the crater of Mount St. Helens, Washington, and several months of data from a station installed near the summit of Augustine Volcano, Alaska in June 2015. Data from the Mount St. Helens Multi-GAS station has been streaming to a public USGS site since early 2015, a first for a permanent Multi-GAS site. Neither station has detected significant changes in gas concentrations or compositions since they were installed, consistent with low levels of seismicity and deformation.

  8. Technical progress report of biological research on the Volcanic Island Surtsey and environment for the year 1976. [Recovery of terrestrial ecosystem on volcanic island following volcano eruption

    Energy Technology Data Exchange (ETDEWEB)

    Fridriksson, S.

    1976-01-01

    The study involves the terrestrial biological research on the volcanic island, Surtsey, off the coast of Iceland and the neighbouring islands and environs of the Westman Islands, which are situated on the Mid-Atlantic Ridge. An eruption of the volcano in 1973 is studied. The topographical changes on Surtsey were studied in August 1976. It is evident that the southwestern side is constantly being eroded and that the island decreases in area of some 7.5 hectares per year. Results are reported from studies of microorganisms, algae, lichens, moss, vascular plants, insects, birds, and soil, and the nitrogen cycle. Emphasis was placed on revegetation and recolonization of plants, insects, and sea birds.

  9. An examination of the resettlement program at Mayon Volcano: what can we learn for sustainable volcanic risk reduction?

    Science.gov (United States)

    Usamah, Muhibuddin; Haynes, Katharine

    2012-05-01

    This paper investigates a resettlement program for communities impacted by volcanic hazards from Mayon volcano in the Philippines. Two resettlement sites are selected, the first FVR-FNM village (named after President Fidel V. Ramos and Mayor Florencio N. Munoz) was settled after the 1993 eruption. The second, Bungkaras Village, was settled after the 2006 eruption and associated typhoon Reming lahar event. These two sites were selected in order to explore the process of relocation over the short and longer term, although the main focus of the study is in the more recently settled Bungkaras Village. The overall aim is to determine if exposure to volcanic hazards has decreased without adding to vulnerability through loss of livelihood, community and culture, and exposure to new risks. A mixed method qualitative approach was utilized including semistructured interviews, participant observations, and a participatory workshop. This enabled an in-depth understanding of life and the challenges faced at the resettlement sites vis-à-vis the original settlements. In order to document the process of site selection, planning, and building, semistructured interviews were conducted with key government officials, emergency managers, and donors of the resettlement projects. This research demonstrates that a volcanic resettlement program must be directed by meaningful consultation with the impacted community who also share in the decision making. Successful resettlement must consider aspects of livelihood security, house design, and the availability of public and lifeline facilities.

  10. Geometric Comparisons of Selected Small Topographically Fresh Volcanoes in the Borealis and Elysium Planitia Volcanic Fields, Mars: Implications for Eruptive Styles

    Science.gov (United States)

    Taylor, K.; Sakimoto, S. E. H.; Mitchell, D.

    2002-01-01

    MOLA (Mars Orbiter Laser Altimeter) data from small, topographically fresh volcanoes from the Elysium and Borealis regions were gridded and analyzed using GMT (Generic Mapping Tools) programs. Results compare eruptive styles of the two regions, and draw conclusions about the different volcanic regions. Additional information is contained in the original extended abstract.

  11. El Estribo Volcanic Complex: Evolution from a shield volcano to a cinder cone, Pátzcuaro Lake, Michoacán, México

    Science.gov (United States)

    Pola, A.; Macías, J. L.; Osorio-Ocampo, S.; Sosa-Ceballos, G.; Garduño-Monroy, V. H.; Martínez-Martínez, J.

    2015-09-01

    El Estribo Volcanic Complex (EVC) is located in the northern part of the Michoacán-Guanajuato Volcanic Field within the Trans-Mexican Volcanic Belt (TMVB). El Estribo is located at the southern edge of the E-W Pátzcuaro fault that belongs to the Pátzcuaro-Jarácuaro graben, a western extension of the E-W Morelia-Acambay fault system. Stratigraphy, geochronology, chemistry, and mineral assemblages suggest that the volcanic complex was constructed in two periods separated by a ~ 100 ka volcanic hiatus: a) emission of lava flows that constructed a shield volcano between 126 ka, and b) mixed phreatomagmatic to Strombolian activity that formed a cinder cone ~ 28 ka. The magmas that fed these monogenetic volcanoes were able to use the same feeding system. The cinder cone itself was constructed by Strombolian fallouts and remobilized scoria beds, followed by an erosion period, and by a mixed phreatomagmatic to magmatic phase (Strombolian fallouts ending with lava flows). Soft-sedimentary deformation of beds and impact sags, cross-bedding, as well as pitting and hydrothermal cracks found in particles support the phreatomagmatic phase. The erupted magmas through time ejected basaltic andesitic lava flows (56.21-58.88% SiO2) that built the shield volcano and then basaltic andesitic scoria (57.65-59.05% SiO2) that constructed the cinder cone. Although they used the same feeding system, the geochemical data and the mineral chemistry of the magmas indicate that the shield volcano and the cinder cone were fed by different magma batches erupted thousands of years apart. Therefore, the location of El Estribo Volcanic Complex along an E-W fault that has generated two sector collapses of the shield volcano to the north may be directly linked to this complex redistribution of the magmatic paths to the surface. Our findings show that magmatic feeding systems within monogenetic volcanic fields could be long lived, questioning the classic view of the monogenetic nature of their

  12. Sr, Nd and Pb isotope and geochemical data from the Quaternary Nevado de Toluca volcano, a source of recent adakitic magmatism, and the Tenango Volcanic Field, Mexico

    Science.gov (United States)

    Martínez-Serrano, Raymundo G.; Schaaf, Peter; Solís-Pichardo, Gabriela; Hernández-Bernal, Ma. del Sol; Hernández-Treviño, Teodoro; Julio Morales-Contreras, Juan; Macías, José Luis

    2004-11-01

    Volcanic activity at Nevado de Toluca (NT) volcano began 2.6 Ma ago with the emission of andesitic lavas, but over the past 40 ka, eruptions have produced mainly lava flows and pyroclastic deposits of predominantly orthopyroxene-hornblende dacitic composition. In the nearby Tenango Volcanic Field (TVF) pyroclastic products and lava flows ranging in composition from basaltic andesite to andesite were erupted at most of 40 monogenetic volcanic centers and were coeval with the last stages of NT. All volcanic rocks in the study area are characterized by a calc-alkaline affinity that is consistent with a subduction setting. Relatively high concentrations of Sr (>460 ppm) coupled with low Y (45 km) that underlies the volcanoes of the study area, the geochemical and isotopic patterns of these rocks indicate low interaction with this crust. NT volcano was constructed at the intersection of three fault systems, and it seems that the Plio-Quaternary E-W system played an important role in the ascent and storage of magmas during the recent volcanic activity in the two regions. Chemical and textural features of orthopyroxene, amphibole and Fe-Ti oxides from NT suggest that crystallization of magmas occurred at polybaric conditions, confirming the rapid upwelling of magmas.

  13. 226Ra or 226Ra/Ba dating of Holocene volcanic rocks: application to Mt. Etna and Merapi volcanoes

    Science.gov (United States)

    Condomines, M.; Gauthier, P. J.; Tanguy, J. C.; Gertisser, R.; Thouret, J. C.; Berthommier, P.; Camus, G.

    2005-02-01

    This paper shows how 226Ra- 230Th disequilibria can be used to date Holocene volcanic rocks from some well selected volcanoes. A systematic study of these disequilibria on historical or well-dated volcanic samples is indeed first required to test the applicability of this method. Two examples are described here to illustrate its potential. In the case of Mt. Etna, the good correlation observed between ( 226Ra) 0 activities at the time of eruption and Th contents in lava flows from the last two millennia [M. Condomines, J.C. Tanguy, V. Michaud, Magma dynamics at Mt. Etna: constraints from U-Th-Ra-Pb radioactive disequilibria and Sr isotopes in historical lavas, Earth Planet. Sci. Lett. 132 (1995) 25-41] is used to infer the ages of several newly analysed lava flows. The calculated ages are in good agreement with those deduced from the archaeomagnetic curve describing the variation of the geomagnetic field direction in southern Italy [J.C. Tanguy, I. Bucur, J.F.C. Thompson, Geomagnetic secular variation in Sicily and revised ages of historic lavas from Mt. Etna, Nature 318 (1985) 453-455, J.C. Tanguy, M. Le Goff, V. Chillemi, A. Paiotti, C. Principe, S. La Delfa, G. Patane, Variation séculaire de la direction du champ géomagnétique enregistrée par les laves de l'Etna et du Vésuve pendant les deux derniers millénaires, C. R. Acad. Sci. Paris 329 (1999) 557-564, J.C. Tanguy, M. Le Goff, C. Principe, S. Arrighi, V. Chillemi, A. Paiotti, S. La Delfa, G. Patane, Archaeomagnetic dating of Mediterranean volcanics of the last 2100 years: validity and limits. Earth Planet. Sci. Lett. 211 (2003) 111-124]. We also present a whole set of new U-series data on historical, recent, and older samples from Merapi (Indonesia), and show that the ( 226Ra)/Ba ratio has probably maintained a quasi-steady state value during at least the past four millennia, and can be used to infer the ( 226Ra) 0/Ba ratio of old volcanics at the time of eruption, and thus their ages. Comparison with

  14. The anatomy of a cinder cone: preliminary paleomagnetic, rock magnetic, structural, and petrologic data from the La Cienega volcano, Cerros del Rio volcanic field, northern New Mexico

    Science.gov (United States)

    Petronis, M. S.; Foucher, M.; Lineline, J.; Van Wyk de Vries, B.

    2011-12-01

    The Cerros del Rio volcanic field is one of several middle Pliocene to Pleistocene basaltic volcanic fields of the axial Rio Grande Rift in central and northern New Mexico. It is a monogenetic volcanic field that comprises about 60 cinder-spatter cones, occupies ~ 700 km2, and ranges in age from 2.7 Ma to 1.1 Ma. Eruptive centers are typically central vent volcanoes, ranging from low-relief shields to steep-sided, breached cinder and spatter cone remnants. They represent short eruptive events that likely were derived from rapidly evolving reservoir-conduit systems. Mining activity has exposed the volcanic plumbing system of the Cienega Mine cinder cone, just west of Santa Fe, NM. Here, geologists from France and USA have been investigating the exposed roots of this eviscerated Pliocene volcano to investigate magma conduit geometry, magma flow structures, and eruption patterns. We are testing models for magma transport and volcano construction using a variety of field and laboratory tools. Common models of volcanic construction envision the magma feeder as a dike or pipe-like conduit transporting molten rock from a deep reservoir to the eruptive vent. We posit that small volcanic pluming systems are inherently more complex and actually involve numerous feeder geometries throughout the volcano lifespan. Our preliminary work suggests that the simple exteriors of some cinder cones hide a long life and complex history, both of which would change the appreciation of the related volcanic hazards in active systems. The Cienega Mine cinder cone consists of several meter- to decimeter-wide intrusions that connect to eruptive centers. These intrusions show a continuity of brittle to ductile structures from their margins to interiors. We have collected samples across each intrusion as well as along strike for anisotropy of magnetic susceptibility (AMS) and petrographic analysis in order to establish magma flow patterns. AMS results yield a remarkably consistent dataset that

  15. Behavior of volatiles in arc volcanism : geochemical and petrologic evidence from active volcanoes in Indonesia

    NARCIS (Netherlands)

    Hoog, J.C.M. de

    2001-01-01

    Large amounts of material are recycled along subduction zones by uprising magmas, of which volcanoes are the surface expression. This thesis focuses on the behavior of volatiles elements (S, Cl, H) during these recycling processes. The study area is the Indonesian arc system, which hosts

  16. Behavior of volatiles in arc volcanism : geochemical and petrologic evidence from active volcanoes in Indonesia

    NARCIS (Netherlands)

    Hoog, J.C.M. de

    2001-01-01

    Large amounts of material are recycled along subduction zones by uprising magmas, of which volcanoes are the surface expression. This thesis focuses on the behavior of volatiles elements (S, Cl, H) during these recycling processes. The study area is the Indonesian arc system, which hosts

  17. Petrology and geochronology of lavas from Ka'ula Volcano: Implications for rejuvenated volcanism of the Hawaiian mantle plume

    Science.gov (United States)

    Garcia, Michael O.; Weis, Dominique; Jicha, Brian R.; Ito, Garrett; Hanano, Diane

    2016-07-01

    Marine surveying and submersible sampling of Ka'ula Volcano, located 100 km off the axis of the Hawaiian chain, revealed widespread areas of young volcanism. New 40Ar/39Ar and geochemical analyses of the olivine-phyric submarine and subaerial volcanic rocks show that Ka'ula is shrouded with 1.9-0.5 Ma alkalic basalts. The ages and chemistry of these rocks overlap with rejuvenated lavas on nearby, northern Hawaiian Island shields (Ni'ihau, Kaua'i and South Kaua'i Swell). Collectively, these rejuvenated lavas cover a vast area (∼7000 km2), much more extensive than any other area of rejuvenated volcanism worldwide. Ka'ula rejuvenated lavas range widely in alkalinity and incompatible element abundances (e.g., up to 10× P2O5 at a given MgO value) and ratios indicating variable degrees of melting of a heterogeneous source. Heavy REE elements in Ka'ula lavas are pinned at a mantle normalized Yb value of 10 ± 1, reflecting the presence of garnet in the source. Trace element ratios indicate the source also contained phlogopite and an Fe-Ti oxide. The new Ka'ula ages show that rejuvenated volcanism was nearly coeval from ∼0.3 to 0.6 Ma along a 450 km segment of the Hawaiian Islands (from West Maui to north of Ka'ula). The ages and volumes for rejuvenated volcanism are inconsistent with all but one geodynamic melting model proposed to date. This model advocates a significant contribution of pyroxenite to rejuvenated magmas. Analyses of olivine phenocryst compositions suggest a major (33-69%) pyroxenite component in Ka'ula rejuvenated lavas, which correlates positively with radiogenic Pb isotope ratios for Ka'ula. This correlation is also observed in lavas from nearby South Kaua'i lavas, as was reported for Atlantic oceanic islands. The presence of pyroxenite in the source may have extended the duration and volume of Hawaiian rejuvenated volcanism.

  18. Directed Volcanic Blast as a Tragedy of October 26Th, 2010 at Merapi Volcano, Central Java

    Directory of Open Access Journals (Sweden)

    Igan S. Sutawidjaja

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i3.163Merapi is an active strato volcano located in Central Java. This volcano is regarded as the most active and most dangerous volcano in Indonesia. Since the twentieth century, the activities have comprised mainly the effusive growth of viscous lava domes and lava tongues, with occasional gravitational collapses of parts of over-steepened domes producing pyroclastic flows, commonly defined as “Merapi-Type”. Since October 2010, however, explosive eruptions of a relatively large size have occurred to VEI 4, and some associated pyroclastic flows were larger and had farther reach than any produced on July 2006. These events may also be regarded as another type of eruptions for Merapi. On October26th, 2010 such event happened, even though it was not caused by pyroclastic flows of the dome collapses, about thirty people were killed including Mbah Marijan, known as the Merapi volcano's spiritual gatekeeper, who was found dead at his home approximately 4 km from the crater. The Yogyakarta Palace subsequently confirmed his death. This time the disaster was caused by a sudden directed blast that took place at 17:02 pm throughout Cangkringan, Kinahrejo Village, at the south flank of Merapi Volcano. The victims were the local people who did not predict the blast threatened their areas, because they believed that the pyroclastic flows from the dome collapses as long as they knew, did not threaten their areas, and pyroclastic flows would flow down following the Boyong River as the closest valley to their village. The blast swept an area about 8 km2, reaching about 5 km in distance, deposited thin ash, and toppled all trees to the south around the Kinahrejo and Pakem areas. The blast that reached Kinahrejo Village seemed to have moderate temperatures, because all trees facing the crater were not burnt. However, the victims were affected by dehydration and blanketed by fine ash.

  19. The bioreactivity of the sub-10 μm component of volcanic ash: Soufrière Hills volcano, Montserrat.

    Science.gov (United States)

    Jones, Timothy; Bérubé, Kelly

    2011-10-30

    With the recent eruption of the Icelandic volcano Eyafallajökull and resulting ash cloud over much of Europe there was considerable concern about possible respiratory hazards. Volcanic ash can contain minerals that are known human respiratory health hazards such as cristobalite. Short-term ash exposures can cause skin sores, respiratory and ocular irritations and exacerbation of pre-existing lung conditions such as asthma. Long-term occupational level exposures to crystalline silicon dioxide can cause lung inflammation, oedema, fibrosis and cancer. The potential health effects would be dependent on factors including mineralogy, surface chemistry, size, and levels and duration of exposure. Bulk ash from the Soufrière Hills volcano was sourced and inhalable (<2.5 μm) ash samples prepared and physicochemically characterised. The fine ash samples were tested for bioreactivity by SDS-PAGE which determined the strength of binding between mineral grains and lung proteins. Selected proteins bound tightly to cristobalite, and bound loosely to other ash components. A positive correlation was seen between the amount of SiO(2) in the sample and the strength of the binding. The strength of binding is a function of the mineral's bioreactivity, and therefore, a potential geo-biomarker of respiratory risk.

  20. Deposition and immersion-mode nucleation of ice by three distinct samples of volcanic ash

    Science.gov (United States)

    Schill, G. P.; Genareau, K.; Tolbert, M. A.

    2015-07-01

    Ice nucleation of volcanic ash controls both ash aggregation and cloud glaciation, which affect atmospheric transport and global climate. Previously, it has been suggested that there is one characteristic ice nucleation efficiency for all volcanic ash, regardless of its composition, when accounting for surface area; however, this claim is derived from data from only two volcanic eruptions. In this work, we have studied the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman microscopy coupled to an environmental cell. Ash from the Fuego (basaltic ash, Guatemala), Soufrière Hills (andesitic ash, Montserrat), and Taupo (Oruanui eruption, rhyolitic ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. In the present study, we find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice from 225 to 235 K at ice saturation ratios of 1.05 ± 0.01, comparable to the mineral dust proxy kaolinite. Since depositional ice nucleation will be more important at colder temperatures, fine volcanic ash may represent a global source of cold-cloud ice nuclei. For immersion freezing relevant to mixed-phase clouds, however, only the Oruanui ash exhibited appreciable heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

  1. Diffuse H_{2} emission: a useful geochemical tool to monitor the volcanic activity at El Hierro volcano system

    Science.gov (United States)

    Pérez, Nemesio M.; Melián, Gladys; González-Santana, Judit; Barrancos, José; Padilla, Germán; Rodríguez, Fátima; Padrón, Eleazar; Hernández, Pedro A.

    2016-04-01

    The occurrence of interfering processes affecting reactive gases as CO2 during its ascent from magmatic bodies or hydrothermal systems toward the surface environment hinders the interpretation of their enrichments in the soil atmosphere and fluxes for volcano monitoring purposes (Marini and Gambardella, 2005). These processes include gas scrubbing by ground-waters and interaction with rocks, decarbonatation processes, biogenic production, etc. Within the rest of the soil gases, particularly interest has been addressed to light and highly mobile gases. They offer important advantages for the detection of vertical permeability structures, because their interaction with the surrounding rocks or fluids during the ascent toward the surface is minimum. H2 is one of the most abundant trace species in volcano-hydrothermal systems and is a key participant in many redox reactions occurring in the hydrothermal reservoir gas (Giggenbach, 1987). Although H2 can be produced in soils by N2-fixing and fertilizing bacteria, soils are considered nowadays as sinks of molecular hydrogen (Smith-Downey et al., 2006). Because of its chemical and physical characteristics, H2 generated within the crust moves rapidly and escapes to the atmosphere. These characteristics make H2 one of the best geochemical indicators of magmatic and geothermal activity at depth. El Hierro is the youngest and the SW-most of the Canary Islands and the scenario of the last volcanic eruption of the archipelago, a submarine eruption that took place 2 km off the southern coast of the island from October 2011 to March 2012. Since at El Hierro Island there are not any surface geothermal manifestations (fumaroles, etc), we have focused our studies on soil degassing surveys. Here we show the results of soil H2 emission surveys that have been carried out regularly since mid-2012. Soil gas samples were collected in ˜600 sites selected based on their accessibility and geological criteria. Soil gases were sampled at ˜40

  2. The polycyclic Lausche Volcano (Lausitz Volcanic Field) and its message concerning landscape evolution in the Lausitz Mountains (northern Bohemian Massif, Central Europe)

    Science.gov (United States)

    Wenger, Erik; Büchner, Jörg; Tietz, Olaf; Mrlina, Jan

    2017-09-01

    The Tertiary Lausitz Volcanic Field covers a broad area encompassing parts of Eastern Saxony (Germany), Lower Silesia (Poland) and North Bohemia (Czech Republic). Volcanism was predominantly controlled by the volcano-tectonic evolution of the Ohře Rift and culminated in the Lower Oligocene. This paper deals with the highest volcano of this area, the Lausche Hill (792.6 m a.s.l.) situated in the Lausitz Mountains. We offer a reconstruction of the volcanic edifice and its eruptive history. Its complex genesis is reflected by six different eruption styles and an associated petrographic variety. Furthermore, the Lausche Volcano provides valuable information concerning the morphological evolution of its broader environs. The remnant of an alluvial fan marking a Middle Paleocene-Lower Eocene (62-50 Ma) palaeo-surface is preserved at the base of the volcano. The deposition of this fan can be attributed to a period of erosion of its nearby source area, the Lausitz Block that has undergone intermittent uplift at the Lausitz Overthrust since the Upper Cretaceous. The Lausche Hill is one of at least six volcanoes in the Lausitz Mountains which show an eminent low level of erosion despite their Oligocene age and position on elevated terrain. These volcanoes are exposed in their superficial level which clearly contradicts their former interpretation as subvolcanoes. Among further indications, this implies that the final morphotectonic uplift of the Lausitz Mountains started in the upper Lower Pleistocene ( 1.3 Ma) due to revived subsidence of the nearby Zittau Basin. It is likely that this neotectonic activity culminated between the Elsterian and Saalian Glaciation ( 320 ka). The formation of the low mountain range was substantially controlled by the intersection of the Lausitz Overthrust and the Ohře Rift.

  3. MATLAB tools for improved characterization and quantification of volcanic incandescence in Webcam imagery; applications at Kilauea Volcano, Hawai'i

    Science.gov (United States)

    Patrick, Matthew R.; Kauahikaua, James P.; Antolik, Loren

    2010-01-01

    Webcams are now standard tools for volcano monitoring and are used at observatories in Alaska, the Cascades, Kamchatka, Hawai'i, Italy, and Japan, among other locations. Webcam images allow invaluable documentation of activity and provide a powerful comparative tool for interpreting other monitoring datastreams, such as seismicity and deformation. Automated image processing can improve the time efficiency and rigor of Webcam image interpretation, and potentially extract more information on eruptive activity. For instance, Lovick and others (2008) provided a suite of processing tools that performed such tasks as noise reduction, eliminating uninteresting images from an image collection, and detecting incandescence, with an application to dome activity at Mount St. Helens during 2007. In this paper, we present two very simple automated approaches for improved characterization and quantification of volcanic incandescence in Webcam images at Kilauea Volcano, Hawai`i. The techniques are implemented in MATLAB (version 2009b, Copyright: The Mathworks, Inc.) to take advantage of the ease of matrix operations. Incandescence is a useful indictor of the location and extent of active lava flows and also a potentially powerful proxy for activity levels at open vents. We apply our techniques to a period covering both summit and east rift zone activity at Kilauea during 2008?2009 and compare the results to complementary datasets (seismicity, tilt) to demonstrate their integrative potential. A great strength of this study is the demonstrated success of these tools in an operational setting at the Hawaiian Volcano Observatory (HVO) over the course of more than a year. Although applied only to Webcam images here, the techniques could be applied to any type of sequential images, such as time-lapse photography. We expect that these tools are applicable to many other volcano monitoring scenarios, and the two MATLAB scripts, as they are implemented at HVO, are included in the appendixes

  4. The western submerged sector of the Ischia volcanic island (Tyrrhenian Sea, Italy): new insights into its volcano-tectonic evolution

    Science.gov (United States)

    Passaro, Salvatore; de Alteriis, Giovanni; Milano, Girolamo; Fedi, Maurizio; Florio, Giovanni

    2010-05-01

    The Island of Ischia is a volcanic complex located in the northern boundary of the Gulf of Naples (south-eastern Tyrrhenian Sea, Italy). The island represents only the 30% of a larger, E-W trending, volcanic ridge and likely controlled by a regional tectonic lineament. Despite the many geo-volcanological and geophysical investigations conducted on the island since long time, still little is the knowledge of its offshore. Several marine surveys have been carried out over the past 10 years from IAMC - CNR research institute (Naples, Italy) mostly in the frame of INGV and GNV projects, funded by Italy Civil Protection Department. Such surveys have largely improved the knowledge of the entire volcanic complex. Multibeam bathymetry surveys has revealed several, previously unexpected, morphological and morphostructural features. Moreover some structural patterns and volcano alignments offshore show similarities with those occurring at a regional scale in the Campania region and, locally, between the island of Procida and Phlegrean Fields. Here we report the joint interpretation of geophysical data focused on the western underwater sector of the island. Interpretation was chiefly based on processing/inversion of magnetic data in turn constrained by bathymetry and seismic reflection profiles. Magnetic data, acquired by the IAMC during two different cruises in 2000 and 2002 onboard of the Urania R/V oceanographic vessel, put in evidence that the western seafloor of Ischia is characterized by the presence of a strong residual magnetic anomaly field of complex behaviour, somewhere correlated to local bathymetry. These two last methods allowed to define and distinguish between undersea and subsurface magnetic (i.e. magmatic) basement. Interpretation was also constrained by seismological data.

  5. Organizational preparedness for and management of volcanic crises at Kīlauea and Mauna Loa volcanoes, Hawaii

    Science.gov (United States)

    Gregg, C. E.; Reeves, A.; Lindell, M. K.; Prater, C.; Joyner, T. A.; Eggert, S.

    2016-12-01

    The eruption of Kīlauea volcano since 1983 has produced a series of crises, the latest one occurring in 2014 and 2015 when a new vent sent lava flows northeastward toward developed areas in the lower Puna District of Kīlauea. The June 27 lava flow took about 2 months to advance to the edge of developed areas in Puna, prompting widespread reaction. Volcanic eruptions often have large economic consequences out of proportion with their magnitudes, and uncertainties about the physical and organizational communication of risk information amplify these losses. This study aims to improve tools to communicate uncertainty of volcanic activity and organizational and individual response, offering clearer and more reliable information to guide civic leaders in issuing appropriate warnings. One significant impediment to risk communication is limited knowledge about the most effective ways to communicate scientific uncertainty through verbal, numeric and graphic methods. The public's demand for near-real time information updates during the June 27 lava crisis, including both written messages and graphics, required some agencies to provide information at a faster rate than in any previous eruption. In order to understand how these and other stakeholders involved with the crisis can better plan for and manage future crises, including implementing evacuation decisions, we conducted a series of interviews and a mental model exercise with stakeholders. We explored their knowledge of local risk communication messages and hazard mitigation efforts and their experiences during the June 27 lava flow crisis. Stakeholders represented county, state and federal agencies and included elected officials, emergency managers, scientists, and other professionals involved with the crisis (traffic engineers, land use planners, police officers, fire fighters). We also assessed factors that influence individual and household preparedness to implement officials' protective action recommendations

  6. A statistical method linking geological and historical eruption time series for volcanic hazard estimations: Applications to active polygenetic volcanoes

    Science.gov (United States)

    Mendoza-Rosas, Ana Teresa; De la Cruz-Reyna, Servando

    2008-09-01

    The probabilistic analysis of volcanic eruption time series is an essential step for the assessment of volcanic hazard and risk. Such series describe complex processes involving different types of eruptions over different time scales. A statistical method linking geological and historical eruption time series is proposed for calculating the probabilities of future eruptions. The first step of the analysis is to characterize the eruptions by their magnitudes. As is the case in most natural phenomena, lower magnitude events are more frequent, and the behavior of the eruption series may be biased by such events. On the other hand, eruptive series are commonly studied using conventional statistics and treated as homogeneous Poisson processes. However, time-dependent series, or sequences including rare or extreme events, represented by very few data of large eruptions require special methods of analysis, such as the extreme-value theory applied to non-homogeneous Poisson processes. Here we propose a general methodology for analyzing such processes attempting to obtain better estimates of the volcanic hazard. This is done in three steps: Firstly, the historical eruptive series is complemented with the available geological eruption data. The linking of these series is done assuming an inverse relationship between the eruption magnitudes and the occurrence rate of each magnitude class. Secondly, we perform a Weibull analysis of the distribution of repose time between successive eruptions. Thirdly, the linked eruption series are analyzed as a non-homogeneous Poisson process with a generalized Pareto distribution as intensity function. As an application, the method is tested on the eruption series of five active polygenetic Mexican volcanoes: Colima, Citlaltépetl, Nevado de Toluca, Popocatépetl and El Chichón, to obtain hazard estimates.

  7. RESEARCH: Effects of Recent Volcanic Eruptions on Aquatic Habitat in the Drift River, Alaska, USA: Implications at Other Cook Inlet Region Volcanoes.

    Science.gov (United States)

    DORAVA; MILNER

    1999-02-01

    / Numerous drainages supporting productive salmon habitat are surrounded by active volcanoes on the west side of Cook Inlet in south-central Alaska. Eruptions have caused massive quantities of flowing water and sediment to enter the river channels emanating from glaciers and snowfields on these volcanoes. Extensive damage to riparian and aquatic habitat has commonly resulted, and benthic macroinvertebrate and salmonid communities can be affected. Because of the economic importance of Alaska's fisheries, detrimental effects on salmonid habitat can have significant economic implications. The Drift River drains glaciers on the northern and eastern flanks of Redoubt Volcano. During and following eruptions in 1989-1990, severe physical disturbances to the habitat features of the river adversely affected the fishery. Frequent eruptions at other Cook Inlet region volcanoes exemplify the potential effects of volcanic activity on Alaska's important commercial, sport, and subsistence fisheries. Few studies have documented the recovery of aquatic habitat following volcanic eruptions. The eruptions of Redoubt Volcano in 1989-1990 offered an opportunity to examine the recovery of the macroinvertebrate community. Macroinvertebrate community composition and structure in the Drift River were similar in both undisturbed and recently disturbed sites. Additionally, macroinvertebrate samples from sites in nearby undisturbed streams were highly similar to those from some Drift River sites. This similarity and the agreement between the Drift River macroinvertebrate community composition and that predicted by a qualitative model of typical macroinvertebrate communities in glacier-fed rivers indicate that the Drift River macroinvertebrate community is recovering five years after the disturbances associated with the most recent eruptions of Redoubt Volcano. KEY WORDS: Aquatic habitat; Volcanoes; Lahars; Lahar-runout flows; Macroinvertebrates; Community structure; Community composition

  8. Global Volcano Locations Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC maintains a database of over 1,500 volcano locations obtained from the Smithsonian Institution Global Volcanism Program, Volcanoes of the World publication. The...

  9. Satellite observations of fumarole activity at Aluto volcano, Ethiopia: Implications for geothermal monitoring and volcanic hazard

    Science.gov (United States)

    Braddock, Mathilde; Biggs, Juliet; Watson, Iain M.; Hutchison, William; Pyle, David M.; Mather, Tamsin A.

    2017-07-01

    Fumaroles are the surface manifestation of hydrothermal circulation and can be influenced by magmatic, hydrothermal, hydrological and tectonic processes. This study investigates the temporal changes in fumarole temperatures and spatial extent on Aluto, a restless volcano in the Main Ethiopian Rift (MER), in order to better understand the controls on fluid circulation and the interaction between the magmatic and hydrothermal systems. Thermal infrared (TIR) satellite images, acquired by the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) over the period of 2004 to 2016, are used to generate time series of the fumarole temperatures and areas. The thermal anomalies identified in the ASTER images coincide with known fumaroles with temperatures > 80 °C and are located on or close to fault structures, which provide a pathway for the rising fluids. Most of the fumaroles, including those along the major zone of hydrothermal upwelling, the Artu Jawe Fault Zone, have pixel-integrated temperature variations of only 2 ± 1.5 °C. The exception are the Bobesa fumaroles located on a hypothesised caldera ring fault which show pixel-integrated temperature changes of up to 9 °C consistent with a delayed response of the hydrothermal system to precipitation. We conclude that fumaroles along major faults are strongly coupled to the magmatic-hydrothermal system and are relatively stable with time, whereas those along shallower structures close to the rift flank are more strongly influenced by seasonal variations in groundwater flow. The use of remote sensing data to monitor the thermal activity of Aluto provides an important contribution towards understanding the behaviour of this actively deforming volcano. This method could be used at other volcanoes around the world for monitoring and geothermal exploration.

  10. Collateral variations between the concentrations of mercury and other water soluble ions in volcanic ash samples and volcanic activity during the 2014-2016 eruptive episodes at Aso volcano, Japan

    Science.gov (United States)

    Marumoto, Kohji; Sudo, Yasuaki; Nagamatsu, Yoshizumi

    2017-07-01

    During 2014-2016, the Aso volcano, located in the center of the Kyushu Islands, Japan, erupted and emitted large amounts of volcanic gases and ash. Two episodes of the eruption were observed; firstly Strombolian magmatic eruptive episodes from 25 November 2014 to the middle of May 2015, and secondly phreatomagmatic and phreatic eruptive episodes from September 2015 to February 2016. Bulk chemical analyses on total mercury (Hg) and major ions in water soluble fraction in volcanic ash fall samples were conducted. During the Strombolian magmatic eruptive episodes, total Hg concentrations averaged 1.69 ± 0.87 ng g- 1 (N = 33), with a range from 0.47 to 3.8 ng g- 1. In addition, the temporal variation of total Hg concentrations in volcanic ash varied with the amplitude change of seismic signals. In the Aso volcano, the volcanic tremors are always observed during eruptive stages and quiet interludes, and the amplitudes of tremors increase at eruptive stages. So, the temporal variation of total Hg concentrations could provide an indication of the level of volcanic activity. During the phreatomagmatic and phreatic eruptive episodes, on the other hand, total Hg concentrations in the volcanic ash fall samples averaged 220 ± 88 ng g- 1 (N = 5), corresponding to 100 times higher than those during the Strombolian eruptive episode. Therefore, it is possible that total Hg concentrations in volcanic ash samples are largely varied depending on the eruptive type. In addition, the ash fall amounts were also largely different among the two eruptive episodes. This can be also one of the factors controlling Hg concentrations in volcanic ash.

  11. The record of magma chamber processes in plagioclase phenocrysts at Thera Volcano, Aegean Volcanic Arc, Greece

    Science.gov (United States)

    Stamatelopoulou-Seymour, Karen; Vlassopoulos, Dimitrios; Pearce, Thomas H.; Rice, Craig

    1990-01-01

    Lavas and pyroclastic rocks throughout the volcanic stratigraphy of the Tertiary-Quaternary volcanic complex of Thera in the Aegean island arc display inhomogenous plagioclase populations and phenocryst resorption textures, interpreted as indicative of magma mixing. Plagioclase zoning characteristics studied by Nomarski and laser interferometry techniques establish three main categories of plagioclase: (i) inherited plagioclase (nucleated in endmember prior to initial mixing event) (ii) in situ plagioclase (nucleated in mixed or hybrid magma) and (iii) xenocrystic plagioclase. Nomarski contrast images and linearized compositional zoning profiles reveal striking differences between calcic and sodic plagioclases, depending on the composition of the lava in which they are hosted. These differences reflect the contrasting effects of changes in physical-chemical parameters in basic vis-a-vis more acidic melts during magma mixing and/or influx of new magma into the subvolcanic magma chamber, as well as the influence of magma chamber dynamics on plagioclase equilibration. Variations in bulk major and trace element abundances of Thera volcanic products reflect the dominant overprint of crystal fractionation, but decoupling between major and trace element fractionation models and variations in incompatible trace element distributions are all indicative of magma mixing processes, consistent with compositional and textural zoning in plagioclases.

  12. Chemistry of ash-leachates to monitor volcanic activity: An application to Popocatepetl volcano, central Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Armienta, M.A., E-mail: victoria@geofisica.unam.mx [Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Circuito Exterior, C.U., Mexico 04510 D.F. (Mexico); De la Cruz-Reyna, S. [Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Circuito Exterior, C.U., Mexico 04510 D.F. (Mexico); Soler, A. [Grup de Mineralogia Aplicada i Medi Ambient, Dep. Cristal.lografia, Mineralogia i Diposits Minerals, Fac. Geologia, Universidad de Barcelona (Spain); Cruz, O.; Ceniceros, N.; Aguayo, A. [Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Circuito Exterior, C.U., Mexico 04510 D.F. (Mexico)

    2010-08-15

    Monitoring volcanic activity and assessing volcanic risk in an on-going eruption is a problem that requires the maximum possible independent data to reduce uncertainty. A quick, relatively simple and inexpensive method to follow the development of an eruption and to complement other monitoring parameters is the chemical analysis of ash leachates, particularly in the case of eruptions related to dome emplacement. Here, the systematic analysis of SO{sub 4}{sup 2-}, Cl{sup -} and F{sup -} concentrations in ash leachates is proposed as a valuable tool for volcanic activity monitoring. However, some results must be carefully assessed, as is the case for S/Cl ratios, since eruption of hydrothermally altered material may be confused with degassing of incoming magma. Sulfur isotopes help to identify SO{sub 4} produced by hydrothermal processes from magmatic SO{sub 2}. Lower S isotopic values correlated with higher F{sup -} percentages represent a better indicator of fresh magmatic influence that may lead to stronger eruptions and emplacement of new lava domes. Additionally, multivariate statistical analysis helps to identify different eruption characteristics, provided that the analyses are made over a long enough time to sample different stages of an eruption.

  13. Short-period volcanic gas precursors to phreatic eruptions: Insights from Poás Volcano, Costa Rica

    Science.gov (United States)

    de Moor, Maarten; Aiuppa, Alessandro; Pacheco, Javier; Avard, Geoffroy; Kern, Christoph; Liuzzo, Marco; Martinez, Maria; Giudice, Gaetano; Fischer, Tobias P.

    2016-01-01

    Volcanic eruptions involving interaction with water are amongst the most violent and unpredictable geologic phenomena on Earth. Phreatic eruptions are exceptionally difficult to forecast by traditional geophysical techniques. Here we report on short-term precursory variations in gas emissions related to phreatic blasts at Poás volcano, Costa Rica, as measured with an in situ multiple gas analyzer that was deployed at the edge of the erupting lake. Gas emitted from this hyper-acid crater lake approaches magmatic values of SO2/CO2 1–6 days prior to eruption. The SO2 flux derived from magmatic degassing through the lake is measureable by differential optical absorption spectrometry (sporadic campaign measurements), which allows us to constrain lake gas output and input for the major gas species during eruptive and non-eruptive periods. We can further calculate power supply to the hydrothermal system using volatile mass balance and thermodynamics, which indicates that the magmatic heat flux into the shallow hydrothermal system increases from ∼27 MW during quiescence to ∼59 MW during periods of phreatic events. These transient pulses of gas and heat from the deeper magmatic system generate both phreatic eruptions and the observed short-term changes in gas composition, because at high gas flux scrubbing of sulfur by the hydrothermal system is both kinetically and thermodynamically inhibited whereas CO2gas is always essentially inert in hyperacid conditions. Thus, the SO2/CO2 of lake emissions approaches magmatic values as gas and power supply to the sub-limnic hydrothermal system increase, vaporizing fluids and priming the hydrothermal system for eruption. Our results suggest that high-frequency real-time gas monitoring could provide useful short-term eruptive precursors at volcanoes prone to phreatic explosions.

  14. Volcanoes: Nature's Caldrons Challenge Geochemists.

    Science.gov (United States)

    Zurer, Pamela S.

    1984-01-01

    Reviews various topics and research studies on the geology of volcanoes. Areas examined include volcanoes and weather, plate margins, origins of magma, magma evolution, United States Geological Survey (USGS) volcano hazards program, USGS volcano observatories, volcanic gases, potassium-argon dating activities, and volcano monitoring strategies.…

  15. Scientific and public responses to the ongoing volcanic crisis at Popocatépetl Volcano, Mexico: Importance of an effective hazards-warning system

    Science.gov (United States)

    de la Cruz-Reyna, Servando; Tilling, Robert I.

    2008-01-01

    Volcanic eruptions and other potentially hazardous natural phenomena occur independently of any human actions. However, such phenomena can cause disasters when a society fails to foresee the hazardous manifestations and adopt adequate measures to reduce its vulnerability. One of the causes of such a failure is the lack of a consistent perception of the changing hazards posed by an ongoing eruption, i.e., with members of the scientific community, the Civil Protection authorities and the general public having diverging notions about what is occurring and what may happen. The problem of attaining a perception of risk as uniform as possible in a population measured in millions during an evolving eruption requires searching for communication tools that can describe—as simply as possible—the relations between the level of threat posed by the volcano, and the level of response of the authorities and the public. The hazards-warning system adopted at Popocatépetl Volcano, called the Volcanic Traffic Light Alert System(VTLAS), is a basic communications protocol that translates volcano threat into seven levels of preparedness for the emergency-management authorities, but only three levels of alert for the public (color coded green–yellow–red). The changing status of the volcano threat is represented as the most likely scenarios according to the opinions of an official scientific committee analyzing all available data. The implementation of the VTLAS was intended to reduce the possibility of ambiguous interpretations of intermediate levels by the endangered population. Although the VTLAS is imperfect and has not solved all problems involved in mass communication and decision-making during a volcanic crisis, it marks a significant advance in the management of volcanic crises in Mexico.

  16. Composition, geometry, and emplacement dynamics of a large volcanic island landslide offshore Martinique: From volcano flank-collapse to seafloor sediment failure?

    Science.gov (United States)

    Brunet, Morgane; Le Friant, Anne; Boudon, Georges; Lafuerza, Sara; Talling, Peter; Hornbach, Matthew; Ishizuka, Osamu; Lebas, Elodie; Guyard, Hervé

    2016-03-01

    Landslides are common features in the vicinity of volcanic islands. In this contribution, we investigate landslides emplacement and dynamics around the volcanic island of Martinique based on the first scientific drilling of such deposits. The evolution of the active Montagne Pelée volcano on this island has been marked by three major flank-collapses that removed much of the western flank of the volcano. Subaerial collapse volumes vary from 2 to 25 km3 and debris avalanches flowed into the Grenada Basin. High-resolution seismic data (AGUADOMAR-1999, CARAVAL-2002, and GWADASEIS-2009) is combined with new drill cores that penetrate up to 430 m through the three submarine landslide deposits previously associated to the aerial flank-collapses (Site U1399, Site U1400, Site U1401, IODP Expedition 340, Joides Resolution, March-April 2012). This combined geophysical and core data provide an improved understanding of landslide processes offshore a volcanic island. The integrated analysis shows a large submarine landslide deposit, without debris avalanche deposits coming from the volcano, comprising up to 300 km3 of remobilized seafloor sediment that extends for 70 km away from the coast and covers an area of 2100 km2. Our new data suggest that the aerial debris avalanche deposit enter the sea but stop at the base of submarine flank. We propose a new model dealing with seafloor sediment failures and landslide propagation mechanisms, triggered by volcanic flank-collapse events affecting Montagne Pelée volcano. Newly recognized landslide deposits occur deeper in the stratigraphy, suggesting the recurrence of large-scale mass-wasting processes offshore the island and thus, the necessity to better assess the associated tsunami hazards in the region.

  17. Scientific and public responses to the ongoing volcanic crisis at Popocatépetl Volcano, Mexico: Importance of an effective hazards-warning system

    Science.gov (United States)

    De la Cruz-Reyna, Servando; Tilling, Robert I.

    2008-02-01

    Volcanic eruptions and other potentially hazardous natural phenomena occur independently of any human actions. However, such phenomena can cause disasters when a society fails to foresee the hazardous manifestations and adopt adequate measures to reduce its vulnerability. One of the causes of such a failure is the lack of a consistent perception of the changing hazards posed by an ongoing eruption, i.e., with members of the scientific community, the Civil Protection authorities and the general public having diverging notions about what is occurring and what may happen. The problem of attaining a perception of risk as uniform as possible in a population measured in millions during an evolving eruption requires searching for communication tools that can describe—as simply as possible—the relations between the level of threat posed by the volcano, and the level of response of the authorities and the public. The hazards-warning system adopted at Popocatépetl Volcano, called the Volcanic Traffic Light Alert System (VTLAS), is a basic communications protocol that translates volcano threat into seven levels of preparedness for the emergency-management authorities, but only three levels of alert for the public (color coded green-yellow-red). The changing status of the volcano threat is represented as the most likely scenarios according to the opinions of an official scientific committee analyzing all available data. The implementation of the VTLAS was intended to reduce the possibility of ambiguous interpretations of intermediate levels by the endangered population. Although the VTLAS is imperfect and has not solved all problems involved in mass communication and decision-making during a volcanic crisis, it marks a significant advance in the management of volcanic crises in Mexico.

  18. Source of the great A.D. 1257 mystery eruption unveiled, Samalas volcano, Rinjani Volcanic Complex, Indonesia.

    Science.gov (United States)

    Lavigne, Franck; Degeai, Jean-Philippe; Komorowski, Jean-Christophe; Guillet, Sébastien; Robert, Vincent; Lahitte, Pierre; Oppenheimer, Clive; Stoffel, Markus; Vidal, Céline M; Surono; Pratomo, Indyo; Wassmer, Patrick; Hajdas, Irka; Hadmoko, Danang Sri; de Belizal, Edouard

    2013-10-15

    Polar ice core records attest to a colossal volcanic eruption that took place ca. A.D. 1257 or 1258, most probably in the tropics. Estimates based on sulfate deposition in these records suggest that it yielded the largest volcanic sulfur release to the stratosphere of the past 7,000 y. Tree rings, medieval chronicles, and computational models corroborate the expected worldwide atmospheric and climatic effects of this eruption. However, until now there has been no convincing candidate for the mid-13th century "mystery eruption." Drawing upon compelling evidence from stratigraphic and geomorphic data, physical volcanology, radiocarbon dating, tephra geochemistry, and chronicles, we argue the source of this long-sought eruption is the Samalas volcano, adjacent to Mount Rinjani on Lombok Island, Indonesia. At least 40 km(3) (dense-rock equivalent) of tephra were deposited and the eruption column reached an altitude of up to 43 km. Three principal pumice fallout deposits mantle the region and thick pyroclastic flow deposits are found at the coast, 25 km from source. With an estimated magnitude of 7, this event ranks among the largest Holocene explosive eruptions. Radiocarbon dates on charcoal are consistent with a mid-13th century eruption. In addition, glass geochemistry of the associated pumice deposits matches that of shards found in both Arctic and Antarctic ice cores, providing compelling evidence to link the prominent A.D. 1258/1259 ice core sulfate spike to Samalas. We further constrain the timing of the mystery eruption based on tephra dispersal and historical records, suggesting it occurred between May and October A.D. 1257.

  19. Seismicity and active tectonics at Coloumbo Reef (Aegean Sea, Greece): Monitoring an active volcano at Santorini Volcanic Center using a temporary seismic network

    Science.gov (United States)

    Dimitriadis, I.; Karagianni, E.; Panagiotopoulos, D.; Papazachos, C.; Hatzidimitriou, P.; Bohnhoff, M.; Rische, M.; Meier, T.

    2009-02-01

    The volcanic center of Santorini Island is the most active volcano of the southern Aegean volcanic arc. Α dense seismic array consisting of fourteen portable broadband seismological stations has been deployed in order to monitor and study the seismo-volcanic activity at the broader area of the Santorini volcanic center between March 2003 and September 2003. Additional recordings from a neighbouring larger scale temporary network (CYCNET) were also used for the relocation of more than 240 earthquakes recorded by both arrays. A double-difference relocation technique was used, in order to obtain optimal focal parameters for the best-constrained earthquakes. The results indicate that the seismic activity of the Santorini volcanic center is strongly associated with the tectonic regime of the broader Southern Aegean Sea area as well as with the volcanic processes. The main cluster of the epicenters is located at the Coloumbo Reef, a submarine volcano of the volcanic system of Santorini Islands. A smaller cluster of events is located near the Anydros Islet, aligned in a NE-SW direction, running almost along the main tectonic feature of the area under study, the Santorini-Amorgos Fault Zone. In contrast, the main Santorini Island caldera is characterized by the almost complete absence of seismicity. This contrast is in very good agreement with recent volcanological and marine studies, with the Coloumbo volcanic center showing an intense high-temperature hydrothermal activity, in comparison to the corresponding low-level activity of the Santorini caldera. The high-resolution hypocentral relocations present a clear view of the volcanic submarine structure at the Coloumbo Reef, showing that the main seismic activity is located within a very narrow vertical column, mainly at depths between 6 and 9 km. The focal mechanisms of the best-located events show that the cluster at the Coloumbo Reef is associated with the "Kameni-Coloumbo Fracture Zone", which corresponds to the

  20. Deposition and immersion mode nucleation of ice by three distinct samples of volcanic ash using Raman spectroscopy

    Science.gov (United States)

    Schill, G. P.; Genareau, K.; Tolbert, M. A.

    2015-01-01

    Ice nucleation on volcanic ash controls both ash aggregation and cloud glaciation, which affect atmospheric transport and global climate. Previously, it has been suggested that there is one characteristic ice nucleation efficiency for all volcanic ash, regardless of its composition, when accounting for surface area; however, this claim is derived from data from only two volcanic eruptions. In this work, we have studied the depositional and immersion freezing efficiency of three distinct samples of volcanic ash using Raman Microscopy coupled to an environmental cell. Ash from the Fuego (basaltic ash, Guatemala), Soufrière Hills (andesitic ash, Montserrat), and Taupo (Oruanui euption, rhyolitic ash, New Zealand) volcanoes were chosen to represent different geographical locations and silica content. All ash samples were quantitatively analyzed for both percent crystallinity and mineralogy using X-ray diffraction. In the present study, we find that all three samples of volcanic ash are excellent depositional ice nuclei, nucleating ice from 225-235 K at ice saturation ratios of 1.05 ± 0.01, comparable to the mineral dust proxy kaolinite. Since depositional ice nucleation will be more important at colder temperatures, fine volcanic ash may represent a global source of cold-cloud ice nuclei. For immersion freezing relevant to mixed-phase clouds, however, only the Oruanui ash exhibited heterogeneous ice nucleation activity. Similar to recent studies on mineral dust, we suggest that the mineralogy of volcanic ash may dictate its ice nucleation activity in the immersion mode.

  1. Volcanic Source Mechanisms from the Low Frequency End of Broadband Recordings: Examples from Fuego Volcano

    Science.gov (United States)

    Waite, G. P.; Brill, K. A.

    2014-12-01

    With the proliferation of broadband recordings from volcanoes, it has become clear that conduit processes produce seismic signals with an extensive range of frequencies. Near the low corner of broadband instruments, the affects of ground rotation can be significant; rotation dominates at periods below the corner. Unraveling the relative influence of translation and rotation on recordings of very-long-period (12 - 120 s) and ultra-long-period (120-600 s) events is an important challenge, because including tilt in inversion of VLP and ULP signals associated with small eruptions can provide constraints on the dynamics of conduit processes. At Fuego volcano in Guatemala, we recorded hundreds of small-scale explosions in field campaigns since 2008 using temporary arrays of seismometers, tiltmeters and microbarometers. Explosions are frequently preceded by 5 to 20 minutes of tilt, indicative of pressurization of the upper conduit. The onset of explosive eruptions, which last from many tens of seconds to more than two minutes, include VLPs with peak periods from less than 30 to nearly 50 seconds. The events are dominated by ash emission that suggests a vulcanian-style downward migration of the magma fragmentation front. Joint inversions of the seismic and tilt signals using synthetic tilt and displacement Green functions provides a more complete view of the eruption process at Fuego. Inversions without tilt point to a source centroid 200 m west of and 300 m below the vent. When lower frequencies are included in the inversion, the source centroid shallows and moves east to a position directly below the vent. We interpret this to reflect a process where the vent seals and pressurizes, producing the ULP signal. The VLP signal results from a rapid change in the deformation of the upper few hundred meters of the conduit due to the ejection of magma during the explosion.

  2. Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex

    Indian Academy of Sciences (India)

    Ashima Saikia; Bibhuti Gogoi; Mansoor Ahmad; Talat Ahmad

    2014-07-01

    The Bathani volcanic and volcano-sedimentary (BVS) sequence is a volcanic and volcano-sedimentary sequence, best exposed near Bathani village in Gaya district of Bihar. It is located in the northern fringe of the Chotanagpur Granite Gneiss Complex (CGGC). The volcano-sedimentary unit comprises of garnet-mica schist, rhyolite, tuff, banded iron formation (BIF) and chert bands with carbonate rocks as enclaves within the rhyolite and the differentiated volcanic sequence comprises of rhyolite, andesite, pillow basalt, massive basalt, tuff and mafic pyroclasts. Emplacement of diverse felsic and mafic rocks together testifies for a multi-stage and multi-source magmatism for the area. The presence of pillow basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption of mafic and felsic magmas resulted in the formation of rhyolite, mafic pyroclasts, and tuff. Mixing and mingling of the felsic and mafic magmas resulted in the hybrid rock andesite. Granites are emplaced later, crosscutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and calc-alkaline affinities of andesite, rhyolite and granite is consistent with their generation in an island arc, subduction related setting. The rocks of the BVS sequence probably mark the collision of the northern and southern Indian blocks during Proterozoic period. The explosive submarine volcanism may be related to culmination of the collision of the aforementioned blocks during the Neoproterozoic (1.0 Ga) as the Grenvillian metamorphism is well established in various parts of CGGC.

  3. Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex

    Science.gov (United States)

    Saikia, Ashima; Gogoi, Bibhuti; Ahmad, Mansoor; Ahmad, Talat

    2014-06-01

    The Bathani volcanic and volcano-sedimentary (BVS) sequence is a volcanic and volcano-sedimentary sequence, best exposed near Bathani village in Gaya district of Bihar. It is located in the northern fringe of the Chotanagpur Granite Gneiss Complex (CGGC). The volcano-sedimentary unit comprises of garnet-mica schist, rhyolite, tuff, banded iron formation (BIF) and chert bands with carbonate rocks as enclaves within the rhyolite and the differentiated volcanic sequence comprises of rhyolite, andesite, pillow basalt, massive basalt, tuff and mafic pyroclasts. Emplacement of diverse felsic and mafic rocks together testifies for a multi-stage and multi-source magmatism for the area. The presence of pillow basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption of mafic and felsic magmas resulted in the formation of rhyolite, mafic pyroclasts, and tuff. Mixing and mingling of the felsic and mafic magmas resulted in the hybrid rock andesite. Granites are emplaced later, cross-cutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and calc-alkaline affinities of andesite, rhyolite and granite is consistent with their generation in an island arc, subduction related setting. The rocks of the BVS sequence probably mark the collision of the northern and southern Indian blocks during Proterozoic period. The explosive submarine volcanism may be related to culmination of the collision of the aforementioned blocks during the Neoproterozoic (1.0 Ga) as the Grenvillian metamorphism is well established in various parts of CGGC.

  4. Use of precipitation and groundwater isotopes to interpret regional hydrology on a tropical volcanic island: Kilauea volcano area, Hawaii

    Science.gov (United States)

    Scholl, M.A.; Ingebritsen, S.E.; Janik, C.J.; Kauahikaua, J.P.

    1996-01-01

    Isotope tracer methods were used to determine flow paths, recharge areas, and relative age for groundwater in the Kilauea volcano area of the Island of Hawaii. A network of up to 66 precipitation collectors was emplaced in the study area and sampled twice yearly for a 3-year period. Stable isotopes in rainfall show three distinct isotopic gradients with elevation, which are correlated with trade wind, rain shadow, and high- elevation climatological patterns. Temporal variations in precipitation isotopes are controlled more by the frequency of storms than by seasonal temperature fluctuations. Results from this study suggest that (1) sampling network design must take into account areal variations in rainfall patterns on islands and in continental coastal areas and (2) isotope/elevation gradients on other tropical islands may be predictable on the basis of similar climatology. Groundwater was sampled yearly in coastal springs, wells, and a few high-elevation springs. Areal contrasts in groundwater stable isotopes and tritium indicate that the volcanic rift zones compartmentalize the regional groundwater system, isolating the groundwater south of Kilauea's summit and rift zones. Part of the Southwest Rift gone appears to act as a conduit for water from higher elevation, but there is no evidence for downrift flow in the springs and shallow wells sampled in the lower East Rift Zone.

  5. Short-term volcano-tectonic earthquake forecasts based on a moving mean recurrence time algorithm: the El Hierro seismo-volcanic crisis experience

    Science.gov (United States)

    García, Alicia; De la Cruz-Reyna, Servando; Marrero, José M.; Ortiz, Ramón

    2016-05-01

    Under certain conditions, volcano-tectonic (VT) earthquakes may pose significant hazards to people living in or near active volcanic regions, especially on volcanic islands; however, hazard arising from VT activity caused by localized volcanic sources is rarely addressed in the literature. The evolution of VT earthquakes resulting from a magmatic intrusion shows some orderly behaviour that may allow the occurrence and magnitude of major events to be forecast. Thus governmental decision makers can be supplied with warnings of the increased probability of larger-magnitude earthquakes on the short-term timescale. We present here a methodology for forecasting the occurrence of large-magnitude VT events during volcanic crises; it is based on a mean recurrence time (MRT) algorithm that translates the Gutenberg-Richter distribution parameter fluctuations into time windows of increased probability of a major VT earthquake. The MRT forecasting algorithm was developed after observing a repetitive pattern in the seismic swarm episodes occurring between July and November 2011 at El Hierro (Canary Islands). From then on, this methodology has been applied to the consecutive seismic crises registered at El Hierro, achieving a high success rate in the real-time forecasting, within 10-day time windows, of volcano-tectonic earthquakes.

  6. Geochemical and petrological indicators of volcanic behavior: Merapi volcano, Java, Indonesia

    Science.gov (United States)

    Troll, V. R.; Deegan, F. M.; Jolis, E. M.; Chadwick, J.; Blythe, L. S.; Freda, C.; Hilton, D. R.; Schwarzkopf, L. M.; Gertisser, R.; Zimmer, M.

    2011-12-01

    Gunung Merapi, one of Indonesia's most active volcanoes, is characterized by long periods of dome growth and intermittent explosive pyroclastic events. Merapi currently degasses continuously through high-T fumaroles (>200°C), and erupts crystal-rich basaltic-andesite that contains a large range of igneous and calc-silicate crustal inclusions. To evaluate mechanisms that trigger explosive eruptions, we sampled lavas, inclusions (xenoliths), and gas from active fumaroles. Additionally, we established a time-integrated experiment reaction series mimicking crustal assimilation at Merapi under magmatic conditions. Merapi lava contains abundant plagioclase crystals which show complex zoning and vary in anorthite (An) content between 40 and 95 mol% across resorption surfaces. A negative correlation between An mol% and other indicators of magmatic fractionation, such as MgO and FeO, has been observed. Moreover, Sr isotope analyses of discrete zones in plagioclase yields 87Sr/86Sr values that notably exceed those of the host lavas. Zones with the highest An content also tend to show the highest radiogenic Sr values, consistent with a Ca-rich, high-87Sr/86Sr crustal contaminant. Abundant metamorphosed limestone xenoliths contain compositionally identical feldspar to the high-An population in the lavas, demonstrating that magma-crust interaction is a significant process at Merapi. Carbon isotope ratios of fumarole CO2 sampled during quiescent degassing periods form a baseline of δ13C2001-2008 = -4.1%. The notable exceptions are the 2006 values, obtained immediately after the eruption and the 6.4 magnitude Yogyakarta earthquake, which show elevated δ13C values up to -2.4%. Notably, the rise in δ13C values coincided with an increase in eruptive intensity and volcano seismicity by a factor of 3 to 5 for several weeks after the earthquake. This is consistent with addition of a late-stage, crustal volatile component added to purely mantle and slab-derived volatile sources

  7. Volcanic processes recorded by inclusions in sanidine megacrystals ejected from Quaternary Rockeskyll volcano, Eifel, Germany

    Science.gov (United States)

    Eilhard, Nicole; Schreuer, Jürgen; Stöckhert, Bernhard

    2016-04-01

    Sanidine megacrystals were ejected by a late stage explosive eruption at the Quaternary Rockeskyll volcanic complex, Eifel volcanic field, Germany. The homogeneous distribution of barium (about 1 % wt BaO equivalent to about 2 mole % celsian component) indicates that the nearly perfect single crystals must have crystallized in the Ostwald-Miers range from a huge reservoir, probably in the roof of a magma chamber. Irregularities during crystal growth caused trapping of hydrous melt inclusions, which are the objective of the present study. The inclusions show a characteristic concentric microstructure, in the following described from the sanidine host towards the inclusion center: (1) Ba is enriched by a factor of 2 to 3 in a ca. 0.01 mm wide rim, compared to the otherwise homogeneous sanidine host; (2) inwards, the continuous rim is overgrown by a thin crust of Ba enriched sanidine with irregular surface; (3) a layer of glass with a composition similar to sanidine; (4) a second, thinner layer of glass slightly reduced in Na2O and K2O, separated from the first glass layer by a sharp interface with approximately spherical shape; (5) a bubble containing a fluid phase, composed of H2O and minor CO2. This record is interpreted as follows: After crystallization of the sanidine megacrystals, a rise in temperature within the magmatic system caused some re-melting of the Ba-rich sanidine around the inclusions. Partitioning of Ba between the small included melt reservoir and the host caused formation of the Ba-rich rim (layer 1) by diffusive exchange. The onset of cooling lead to crystallization of the thin sanidine crust (layer 2). Finally, very rapid decompression and cooling during the subsequent explosive eruption caused sequential phase separation (two stages) in the remaining melt, the denser melt phase (layers 3 and 4) quenched to glass, the complementary low-density volatile-rich phase forming the central bubble. In summary, the microstructure and phase composition of

  8. Discovery of an active shallow submarine silicic volcano in the northern Izu-Bonin Arc: volcanic structure and potential hazards of Oomurodashi Volcano (Invited)

    Science.gov (United States)

    Tani, K.; Ishizuka, O.; Nichols, A. R.; Hirahara, Y.; Carey, R.; McIntosh, I. M.; Masaki, Y.; Kondo, R.; Miyairi, Y.

    2013-12-01

    Oomurodashi is a bathymetric high located ~20 km south of Izu-Oshima, an active volcanic island of the northern Izu-Bonin Arc. Using the 200 m bathymetric contour to define its summit dimensions, the diameter of Oomurodashi is ~20 km. Oomurodashi has been regarded as inactive, largely because it has a vast flat-topped summit at 100 - 150 meters below sea level (mbsl). During cruise NT07-15 of R/V Natsushima in 2007, we conducted a dive survey in a small crater, Oomuro Hole, located in the center of the flat-topped summit, using the remotely-operated vehicle (ROV) Hyper-Dolphin. The only heat flow measurement conducted on the floor of Oomuro Hole during the dive recorded an extremely high value of 4,200 mW/m2. Furthermore, ROV observations revealed that the southwestern wall of Oomuro Hole consists of fresh rhyolitic lavas. These findings suggest that Oomurodashi is in fact an active silicic submarine volcano. To confirm this hypothesis, we conducted detailed geological and geophysical ROV Hyper-Dolphin (cruise NT12-19). In addition to further ROV surveys, we carried out single-channel seismic (SCS) surveys across Oomurodashi in order to examine the shallow structures beneath the current edifice. The ROV surveys revealed numerous active hydrothermal vents on the floor of Oomuro Hole, at ~200 mbsl, with maximum water temperature measured at the hydrothermal vents reaching 194°C. We also conducted a much more detailed set of heat flow measurements across the floor of Oomuro Hole, detecting very high heat flows of up to 29,000 mW/m2. ROV observations revealed that the area surrounding Oomuro Hole on the flat-topped summit of Oomurodashi is covered by extensive fresh rhyolitic lava and pumice clasts with minimum biogenetic or manganese cover, suggesting recent eruption(s). These findings strongly indicate that Oomurodashi is an active silicic submarine volcano, with recent eruption(s) occurring from Oomuro Hole. Since the summit of Oomurodashi is in shallow water, it

  9. Relationship between regional changes of soil physical properties and volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali, Indonesia

    Science.gov (United States)

    Tanaka, T.; Sunarta, N.

    1994-04-01

    The present paper shows the relationship between the regional changes of soil physical properties and the volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali, Indonesia, from the hydrogeological point of view based on the data obtained from field observations and laboratory experiments. The Bali soils data showed marked differences in regional distribution and their characteristics are closely correlated to the distribution of the volcanic stratigraphy derived from the Batur volcanic activities with the eruption about 23,700 years ago. On the basis of these data, the hydrogeological situation of the slope are presented schematically and groundwater flow regimes on the slope, such as recharge and discharge areas, are also classified according to the hydrogeological information. These classifications of groundwater flow regimes are useful to consider the occurrence of hydrological phenomena such as springs and paddy field distributions observed on the slope.

  10. The perception of volcanic risk in Kona communities from Mauna Loa and Hualālai volcanoes, Hawai'i

    Science.gov (United States)

    Gregg, Chris E.; Houghton, B.F.; Johnston, David M.; Paton, Douglas; Swanson, D.A.

    2004-01-01

    Volcanic hazards in Kona (i.e. the western side of the island of Hawai'i) stem primarily from Mauna Loa and Huala??lai volcanoes. The former has erupted 39 times since 1832. Lava flows were emplaced in Kona during seven of these eruptions and last impacted Kona in 1950. Huala??lai last erupted in ca. 1800. Society's proximity to potential eruptive sources and the potential for relatively fast-moving lava flows, coupled with relatively long time intervals since the last eruptions in Kona, are the underlying stimuli for this study of risk perception. Target populations were high-school students and adults ( n =462). Using these data, we discuss threat knowledge as an influence on risk perception, and perception as a driving mechanism for preparedness. Threat knowledge and perception of risk were found to be low to moderate. On average, fewer than two-thirds of the residents were aware of the most recent eruptions that impacted Kona, and a minority felt that Mauna Loa and Huala??lai could ever erupt again. Furthermore, only about one-third were aware that lava flows could reach the coast in Kona in less than 3 h. Lava flows and ash fall were perceived to be among the least likely hazards to affect the respondent's community within the next 10 years, whereas vog (volcanic smog) was ranked the most likely. Less than 18% identified volcanic hazards as amongst the most likely hazards to affect them at home, school, or work. Not surprisingly, individual preparedness measures were found on average to be limited to simple tasks of value in frequently occurring domestic emergencies, whereas measures specific to infrequent hazard events such as volcanic eruptions were seldom adopted. Furthermore, our data show that respondents exhibit an 'unrealistic optimism bias' and infer that responsibility for community preparedness for future eruptions primarily rests with officials. We infer that these respondents may be less likely to attend to hazard information, react to warnings as

  11. Decompressional Volcanism Following Giant Landslide Events at a Miocene Shield- Volcano, Teno, Tenerife: Evidence From Field Observations, Augite and Olivine Chemistry, and Chemical Thermobarometry

    Science.gov (United States)

    Hansteen, T. H.; Longpré, M.; Troll, V. R.; Walter, T. R.

    2006-12-01

    Giant landslides play a major role in the evolution of large oceanic shield-volcanoes around the globe. The removal of a significant portion of the volcanic edifice due to lateral collapse is thought to supersede the effect of erosion and subsidence in the process of island decay. On the other hand, rapid constructional phases appear to frequently follow giant mass-wasting and are generally concentrated in the region affected by the collapse (e.g. Réunion, La Palma, Fogo). The rapid unloading of up to thousands of km3 of near-surface rocks must decompress parts of the volcanic edifice, which in turn may affect the magmatic system [1,2]. Located in north-western Tenerife, Teno is a deeply eroded Miocene shield-volcano which has suffered at least two giant lateral collapses between 5-6 Ma [3]. Incised valleys dissect the structure of the old volcano and expose ancient landslide scars. Extensive debris avalanche deposits typically include juvenile pyroclastic material, suggesting that explosive volcanic activity was contemporaneous with landsliding. Moreover, post- collapse stratigraphy is marked by numerous thick ultramafic lava flows (basanites, ankaramites, picrites, SiO2 volcano may have disrupted any shallow magma reservoir existing prior to the collapse, resulting in pyroclastic activity. The decompression effect may also have triggered the rapid ascent of mafic melts stored at mantle depth, causing mixing of multiple magma batches and the aggregation of their crystal populations. The very steep normal zonation at the rims of many augite and olivine crystals may be attributed to a rapid change in the P-T conditions and/or the melt chemical composition. [1] Presley et al. 1997, Bull Volcanol. [2] Pinet & Jaupart 2005, JVGR. [3] Walter & Schmincke 2002, Int J Earth Sci.[4] Putirka et al. 2003, Am Min.

  12. Slope instability induced by volcano-tectonics as an additional source of hazard in active volcanic areas: the case of Ischia island (Italy)

    Science.gov (United States)

    Della Seta, Marta; Marotta, Enrica; Orsi, Giovanni; de Vita, Sandro; Sansivero, Fabio; Fredi, Paola

    2012-01-01

    Ischia is an active volcanic island in the Gulf of Naples whose history has been dominated by a caldera-forming eruption (ca. 55 ka) and resurgence phenomena that have affected the caldera floor and generated a net uplift of about 900 m since 33 ka. The results of new geomorphological, stratigraphical and textural investigations of the products of gravitational movements triggered by volcano-tectonic events have been combined with the information arising from a reinterpretation of historical chronicles on natural phenomena such as earthquakes, ground deformation, gravitational movements and volcanic eruptions. The combined interpretation of all these data shows that gravitational movements, coeval to volcanic activity and uplift events related to the long-lasting resurgence, have affected the highly fractured marginal portions of the most uplifted Mt. Epomeo blocks. Such movements, mostly occurring since 3 ka, include debris avalanches; large debris flows (lahars); smaller mass movements (rock falls, slumps, debris and rock slides, and small debris flows); and deep-seated gravitational slope deformation. The occurrence of submarine deposits linked with subaerial deposits of the most voluminous mass movements clearly shows that the debris avalanches impacted on the sea. The obtained results corroborate the hypothesis that the behaviour of the Ischia volcano is based on an intimate interplay among magmatism, resurgence dynamics, fault generation, seismicity, slope oversteepening and instability, and eruptions. They also highlight that volcano-tectonically triggered mass movements are a potentially hazardous phenomena that have to be taken into account in any attempt to assess volcanic and related hazards at Ischia. Furthermore, the largest mass movements could also flow into the sea, generating tsunami waves that could impact on the island's coast as well as on the neighbouring and densely inhabited coast of the Neapolitan area.

  13. On the predictability of volcano-tectonic events by low frequency seismic noise analysis at Teide-Pico Viejo volcanic complex, Canary Islands

    Directory of Open Access Journals (Sweden)

    M. Tárraga

    2006-01-01

    Full Text Available The island of Tenerife (Canary Islands, Spain, is showing possible signs of reawakening after its last basaltic strombolian eruption, dated 1909 at Chinyero. The main concern relates to the central active volcanic complex Teide - Pico Viejo, which poses serious hazards to the properties and population of the island of Tenerife (Canary Islands, Spain, and which has erupted several times during the last 5000 years, including a subplinian phonolitic eruption (Montaña Blanca about 2000 years ago. In this paper we show the presence of low frequency seismic noise which possibly includes tremor of volcanic origin and we investigate the feasibility of using it to forecast, via the material failure forecast method, the time of occurrence of discrete events that could be called Volcano-Tectonic or simply Tectonic (i.e. non volcanic on the basis of their relationship to volcanic activity. In order to avoid subjectivity in the forecast procedure, an automatic program has been developed to generate forecasts, validated by Bayes theorem. A parameter called 'forecast gain' measures (and for the first time quantitatively what is gained in probabilistic terms by applying the (automatic failure forecast method. The clear correlation between the obtained forecasts and the occurrence of (Volcano-Tectonic seismic events - a clear indication of a relationship between the continuous seismic noise and the discrete seismic events - is the explanation for the high value of this 'forecast gain' in both 2004 and 2005 and an indication that the events are Volcano-Tectonic rather than purely Tectonic.

  14. Origin and age of the Volcanic Rocks of Tláloc Volcano, Sierra Nevada, Central Mexico

    Science.gov (United States)

    Meier, M.; Grobéty, B.; Arce, J. L.; Rueda, H.

    2007-05-01

    The Tláloc volcano (TV) is a 4125 m high stratovolcano of the Trans Mexican Volcanic Belt (TMVB) and is located in the northern end of the N-S trending Sierra Nevada, 30 km NE of Mexico City. Few data on the petrological and temporal evolution of TV have been published to date. Recently dated deposits gave ages between 32'000 and 34'500±500 years BP (Huddart and Gonzalez, 2004). Mapping and sampling of extrusive rocks in the summit region of TV revealed a dome structure with radiating lava flows consisting of dacitic rocks containing plagioclase and hornblende phenocrysts. Some flows, however, seem to be associated with a collapse structure E of the main summit. Crossing relationships indicate that this structure is older (“Paleo Tláloc”). A stratigraphy of the pyroclastic deposits was established along the northern slope of TV. From the numerous pyroclastic flows, separated by paleosoils and fluviatile deposits, only two pumice and one block and ash flow (BAF) have regional extent. Their thickness - distance relationship and their granulometry point to major explosive events. A carbonized wood sample from the BAF deposit gave ages similar to the previous ages (33'180±550 yr BP and 23'170±270 yr BP), a sample from a pyroclastic flow gave even a younger age (16'620±110 yr BP), suggesting that TV remained active also after the volcanoes Iztaccíhuatl and Popocatépetl further to the South started their activity. Based on these preliminary data it may be necessary to reconsider the accepted scenario of the temporal evolution of the central section of the TMVB, which assumes that the activity migrates from North to South with time. Huddart, D. and Gonzalez, S., 2004. Pyroclastic flows and associated sediments, Tláloc-Telapón, piedmont fringe of the eastern basin of Mexico. In: G.J. Aguirre-Diaz, Macías, J.L., and Siebe, C., (Editor), Penrose Conference. UNAM, Metepec, Puebla, Mexico, pp. 35.

  15. Estimating volume of deposits associated with landslides on volcanic landscapes in the SW flank of the volcano Pico de Orizaba, Puebla-Veracruz

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    Gabriel Legorreta Paulín

    2017-03-01

    Full Text Available Landslides that occur along river systems are very common and have the potential to cause harm to human, to its infrastructure or affect their socio-economic activity. This dynamic is magnified in territories where morphological contrasts are very marked; as in the border between the mountains and subhorizontal land. This is especially true for volcanic terrains where volcanic activity can trigger voluminous landslides along stream systems by sector and flank collapse and where high seasonal rainfall on terrains covered by poorly consolidated materials produces small but hazardous landslides and debris flows that occur continually along stream systems during the volcanic repose periods. Those type of landslides can deliver volumes of hundreds and millions cubic meters that create a potentially hazardous situation for people and property down the valleys. The study of landslides in volcanic terrains through a Geographic Information System (GIS and under a geomorphological criterion, have allowed to develop a comprehensive methodology linked to the development of multi-temporal inventory, with susceptibility and volume estimation of displaced material. The aim of this research is to develop a method (protocol for landslide susceptibility and landslide volume assessment of potentially unstable volcanic landscapes in order to be helpful in mitigating landslide damages to human settlements. Pico de Orizaba volcano is the highest volcano in Mexico. The volcano has been affected by large flank collapse landslides throughout its geological history. These events have partially destroyed the cone as it happened in Bezymianny volcano and St. Elena volcano. In this volcano, the risk associated with landslide and debris flows, is increased by the growing of human settlements along the hillslopes and by the subsistence agriculture, and deforestation. This situation is favored by a volcanic calm that has lasted 147 years, approximate. These conditions create a

  16. Long-range hazard assessment of volcanic ash dispersal for a Plinian eruptive scenario at Popocatépetl volcano (Mexico): implications for civil aviation safety

    Science.gov (United States)

    Bonasia, Rosanna; Scaini, Chirara; Capra, Lucia; Nathenson, Manuel; Siebe, Claus; Arana-Salinas, Lilia; Folch, Arnau

    2013-01-01

    Popocatépetl is one of Mexico’s most active volcanoes threatening a densely populated area that includes Mexico City with more than 20 million inhabitants. The destructive potential of this volcano is demonstrated by its Late Pleistocene–Holocene eruptive activity, which has been characterized by recurrent Plinian eruptions of large magnitude, the last two of which destroyed human settlements in pre-Hispanic times. Popocatépetl’s reawakening in 1994 produced a crisis that culminated with the evacuation of two villages on the northeastern flank of the volcano. Shortly after, a monitoring system and a civil protection contingency plan based on a hazard zone map were implemented. The current volcanic hazards map considers the potential occurrence of different volcanic phenomena, including pyroclastic density currents and lahars. However, no quantitative assessment of the tephra hazard, especially related to atmospheric dispersal, has been performed. The presence of airborne volcanic ash at low and jet-cruise atmospheric levels compromises the safety of aircraft operations and forces re-routing of aircraft to prevent encounters with volcanic ash clouds. Given the high number of important airports in the surroundings of Popocatépetl volcano and considering the potential threat posed to civil aviation in Mexico and adjacent regions in case of a Plinian eruption, a hazard assessment for tephra dispersal is required. In this work, we present the first probabilistic tephra dispersal hazard assessment for Popocatépetl volcano. We compute probabilistic hazard maps for critical thresholds of airborne ash concentrations at different flight levels, corresponding to the situation defined in Europe during 2010, and still under discussion. Tephra dispersal mode is performed using the FALL3D numerical model. Probabilistic hazard maps are built for a Plinian eruptive scenario defined on the basis of geological field data for the “Ochre Pumice” Plinian eruption (4965 14C

  17. Long Period (LP) volcanic earthquake source location at Merapi volcano by using dense array technics

    Science.gov (United States)

    Metaxian, Jean Philippe; Budi Santoso, Agus; Laurin, Antoine; Subandriyo, Subandriyo; Widyoyudo, Wiku; Arshab, Ghofar

    2015-04-01

    Since 2010, Merapi shows unusual activity compared to last decades. Powerful phreatic explosions are observed; some of them are preceded by LP signals. In the literature, LP seismicity is thought to be originated within the fluid, and therefore to be representative of the pressurization state of the volcano plumbing system. Another model suggests that LP events are caused by slow, quasi-brittle, low stress-drop failure driven by transient upper-edifice deformations. Knowledge of the spatial distribution of LP events is fundamental for better understanding the physical processes occurring in the conduit, as well as for the monitoring and the improvement of eruption forecasting. LP events recorded at Merapi have a spectral content dominated by frequencies between 0.8 and 3 Hz. To locate the source of these events, we installed a seismic antenna composed of 4 broadband CMG-6TD Güralp stations. This network has an aperture of 300 m. It is located on the site of Pasarbubar, between 500 and 800 m from the crater rim. Two multi-parameter stations (seismic, tiltmeter, S-P) located in the same area, equipped with broadband CMG-40T Güralp sensors may also be used to complete the data of the antenna. The source of LP events is located by using different approaches. In the first one, we used a method based on the measurement of the time delays between the early beginnings of LP events for each array receiver. The observed differences of time delays obtained for each pair of receivers are compared to theoretical values calculated from the travel times computed between grid nodes, which are positioned in the structure, and each receiver. In a second approach, we estimate the slowness vector by using MUSIC algorithm applied to 3-components data. From the slowness vector, we deduce the back-azimuth and the incident angle, which give an estimation of LP source depth in the conduit. This work is part of the Domerapi project funded by French Agence Nationale de la Recherche (https

  18. The effect of shear on permeability in a volcanic conduit: a case study at Unzen volcano, Japan

    Science.gov (United States)

    Ashworth, James; Lavallée, Yan; Wallace, Paul; Lamur, Anthony; Kendrick, Jackie; Miwa, Takahiro

    2016-04-01

    The efficiency of outgassing at volcanoes is a function of permeability, and exerts a major influence on the type of eruptive behaviour exhibited. Understanding how shear affects the permeability profile across volcanic conduits is therefore a key part of understanding volcanic processes and the associated hazards. During the final months of the 1990-1995 eruption of Unzen volcano in southern Japan, extrusion of a dacite spine followed a period of endogenous dome growth. Many of the resulting formations are relatively accessible, allowing for the study of a variety of associated deformation phenomena. One of these formations, a ~6 m wide block, is a section of the extruded spine, that forms the basis for this study on shallow conduit processes. It displays a textural gradation from highly sheared rock to rock with negligible deformation, and is bounded at the high shear end by an agglutinated block of gouge that is thought to represent the conduit margin. A multi-faceted approach was taken to investigate the variation of permeability across the spine and its implications for processes occurring within the conduit. The permeability was measured at several points along the exposed surface of the spine transect using a field permeameter. Sample blocks from four of these locations were collected and tested in the lab using a hydrostatic pressure vessel water-flow permeameter and categorized as: gouge; highest shear; moderate shear; negligible shear. Each block was tested in three orthogonal axes: one perpendicular to observed shear; and two in the plane of shear. For each of these rocks, permeability and porosity measurements were made at a wide range of effective pressures (5 to 100 MPa), using a controlled upstream/downstream pore pressure gradient of 0.5 MPa (at an average pore pressure of 1.25 MPa). Thin sections of each sample were also taken prepared and analysed to describe the primary microstructures controlling the permeability of the rock. Textural analysis

  19. Foci of Volcanoes

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, I.

    1974-01-01

    One may assume a center of volcanic activities beneath the edifice of an active volcano, which is here called the focus of the volcano. Sometimes it may be a ''magma reservoir''. Its depth may differ with types of magma and change with time. In this paper, foci of volcanoes are discussed from the viewpoints of four items: (1) Geomagnetic changes related with volcanic activities; (2) Crustal deformations related with volcanic activities; (3) Magma transfer through volcanoes; and (4) Subsurface structure of calderas.

  20. Smoothed particle hydrodynamic modeling of volcanic debris flows: Application to Huiloac Gorge lahars (Popocatépetl volcano, Mexico)

    Science.gov (United States)

    Haddad, Bouchra; Palacios, David; Pastor, Manuel; Zamorano, José Juan

    2016-09-01

    Lahars are among the most catastrophic volcanic processes, and the ability to model them is central to mitigating their effects. Several lahars recently generated by the Popocatépetl volcano (Mexico) moved downstream through the Huiloac Gorge towards the village of Santiago Xalitzintla. The most dangerous was the 2001 lahar, in which the destructive power of the debris flow was maintained throughout the extent of the flow. Identifying the zone of hazard can be based either on numerical or empirical models, but a calibration and validation process is required to ensure hazard map quality. The Geoflow-SPH depth integrated numerical model used in this study to reproduce the 2001 lahar was derived from the velocity-pressure version of the Biot-Zienkiewicz model, and was discretized using the smoothed particle hydrodynamics (SPH) method. The results of the calibrated SPH model were validated by comparing the simulated deposit depth with the field depth measured at 16 cross sections distributed strategically along the gorge channel. Moreover, the dependency of the results on topographic mesh resolution, initial lahar mass shape and dimensions is also investigated. The results indicate that to accurately reproduce the 2001 lahar flow dynamics the channel topography needed to be discretized using a mesh having a minimum 5 m resolution, and an initial lahar mass shape that adopted the source area morphology. Field validation of the calibrated model showed that there was a satisfactory relationship between the simulated and field depths, the error being less than 20% for 11 of the 16 cross sections. This study demonstrates that the Geoflow-SPH model was able to accurately reproduce the lahar path and the extent of the flow, but also reproduced other parameters including flow velocity and deposit depth.

  1. Shallow crustal velocities and volcanism suggested from ambient noise studies using a dense broadband seismic network in the Tatun Volcano Group of Taiwan

    Science.gov (United States)

    Huang, Yu-Chih; Lin, Cheng-Horng; Kagiyama, Tsuneomi

    2017-07-01

    The Tatun Volcano Group (TVG) is situated adjacent to the Taipei metropolis and was active predominantly around 0.8-0.2 Ma (Pleistocene). Various recent lines of evidence suggest that the TVG is a potentially active volcano and that future volcanic eruptions cannot be ruled out. Geothermal activities are largely constrained to faults, but the relationship between volcanism and detailed velocity structures is not well understood. We analyzed ambient seismic noise of daily vertical components from 2014 using a dense seismic network of 40 broadband stations. We selected a 0.02° grid spacing to construct 2D and 3D shallow crustal phase velocity maps in the 0.5-3 s period band. Two S-wave velocity profiles transect Chishingshan (Mt. CS) in the shallow 3 km crust are further derived. The footwall of the Shanchiao Fault is dominated by low velocity, which may relate to Tertiary bedrock buried under andesitic lava flows dozens to hundreds of meters thick. The hanging wall of the Shanchiao Fault is the location of recent major volcanic activities. Low velocity zones in the southeast of Dayoukeng (DYK) may be interpreted as hydrothermal reservoirs or water-saturated Tertiary bedrock related to Cenozoic structures in the shallow crust. High velocities conspicuously dominate the east of the TVG, where the earliest stages of volcanism in the TVG are located, but where surface hydro-geothermal activities were absent in recent times. Between the Shanchiao Fault and Kanchiao Fault high velocities were detected, which converge below Mt. CS and may be related to early stages of magma conduits that gradually consolidated. These two faults may play a significant role with the TVG. The submarine volcanism adjacent to the Keelung coastline also requires further attention.

  2. A Scientific Excursion: Volcanoes.

    Science.gov (United States)

    Olds, Henry, Jr.

    1983-01-01

    Reviews an educationally valuable and reasonably well-designed simulation of volcanic activity in an imaginary land. VOLCANOES creates an excellent context for learning information about volcanoes and for developing skills and practicing methods needed to study behavior of volcanoes. (Author/JN)

  3. Advective diffusion of volcanic plume captured by dense GNSS network around Sakurajima volcano: a case study of the vulcanian eruption on July 24, 2012

    Science.gov (United States)

    Ohta, Yusaku; Iguchi, Masato

    2015-09-01

    Data from a dense GNSS network were used to investigate the temporal and spatial development of a volcanic plume during the eruptive event at Sakurajima volcano in Japan on July 24, 2012. We extracted the post-fit phase residuals (PPR) of ionosphere-free linear combinations for each satellite based on the precise point positioning (PPP) approach. Temporal and spatial PPR anomalies clearly detected the movement of the volcanic plume. The maximum height of the crossing points of anomalous PPR paths was determined to be approximately 4000 m. We also compared the estimated wet zenith tropospheric delay with the estimated PPR anomalies, which suggested that we might successfully extract the PPR anomalies caused by the eruptive event. We then compared the PPR with the signal-to-noise ratio (SNR) anomalies. Only the path passing just above the crater showed significant change in the SNR value, suggesting that the volcanic ash and the water vapor within the volcanic plume became separated after reaching a high altitude because of ash fall during the plume's lateral movement. Each of the two observables might reflect different characteristics of the water vapor and volcanic ash.

  4. Whakaari (White Island volcano, New Zealand): Magma-hydrothermal laboratory

    Science.gov (United States)

    Lavallee, Yan; Heap, Michael J.; Reuschle, Thierry; Mayer, Klaus; Scheu, Bettina; Gilg, H. Albert; Kennedy, Ben M.; Letham-Brake, Mark; Jolly, Arthur; Dingwell, Donald B.

    2015-04-01

    Whakaari, active andesitic stratovolcano of the Taupo Volcanic Zone (New Zealand), hosts an open, highly reactive hydrothermal system in the amphitheatre of an earlier sector collapse. Its recent volcanic activity is primarily characterized by sequences of steam-driven (phreatic) and phreatomagmatic explosive eruptions, although a lava dome briefly extruded in 2012. The volcano provides a natural laboratory for the study of aggressive fluids on the permeability of the hydrothermal system, on phreatomagmatic volcanism as well as on the volcano edifice structural stability. Here, we present a holistic experimental dataset on the reservoir rocks properties (mineralogy, permeability, seismic velocity) and their response to changes in stress (strength, deformation mechanisms, fragmentation) and temperature (mineralogical breakdown). We show that the advance degree of alteration in the system, nearly replaced all the original rock-forming minerals. This alteration has produced generally weak rocks, which, when subjected to a differential stress, can undergo transition from a dilatant response (brittle) to a compactant response with a mere confining pressure of about 15-20 MPa (corresponding to depth of about 1 km). Thermal stressing experiments reveal that the alteration phases breakdown at 500 °C (alunite) and 700 °C (dehydrated alum and sulphur), generating much weakened skeletal rocks, deteriorated by a mass loss of 20 wt.%, resulting in an increase in porosity and permeability of about 15 vol.% and an order of magnitude, respectively. Novel thermal stressing tests at high-heating rates (violence of these steam-driven events and highlight the predisposition of thermally unstable rocks in hydrothermal system to undergo sudden phreatic eruptions.

  5. Influence of the substrate on maar-diatreme volcanoes — An example of a mixed setting from the Pali Aike volcanic field, Argentina

    Science.gov (United States)

    Ross, Pierre-Simon; Delpit, Séverine; Haller, Miguel J.; Németh, Károly; Corbella, Hugo

    2011-04-01

    The morphologic parameters, pyroclastic deposits and evolution of maar-diatreme volcanoes are affected by the type of environment in which they are emplaced. End-member cases are a hard substrate (rocks) and a soft substrate (unconsolidated volcaniclastic or sedimentary deposits). In this paper, we present an example of a volcanic complex emplaced in a mixed hard-soft setting from the Pali Aike volcanic field (PAVF) near the Argentina-Chile border. The Plio-Pleistocene PAVF is an alkaline, mafic, back-arc monogenetic field which contains over 100 phreatomagmatic volcanoes. The studied volcanic complex contains two large coalescent maars overlain by scoria and spatter. The 1.4 × 1.3 km East Maar has better exposures than the shallower, 1.9 km-wide West Maar and seems to have been less modified by post-eruptive processes. The tephra rim of the East Maar was studied in detail and we infer it was produced mostly by base surges from phreatomagmatic eruption columns, with rare instances of intercalated scoria fall layers. Based on regional information, the general pre-maar stratigraphy is dominated by sedimentary and volcaniclastic rocks of the Magallanes Basin, including a thick poorly consolidated upper unit dating from the Miocene. These are overlain by Plio-Pleistocene fluvio-glacial deposits and PAVF lavas, some of which are exposed in the East Maar just below the phreatomagmatic deposits. All of these units are represented as lithic clasts in the tephra rim of the East Maar, the most abundant being the clasts from the earlier basaltic lavas and rock fragments derived from the glacial deposits. There is no specific evidence for a deep diatreme under the East Maar, and in this particular case, the mixed environment seems to have produced a maar-diatreme volcano typical of a soft substrate.

  6. Paleo-tsunami and Tephrochronologic Investigations into the Late Holocene Volcanic History of Augustine Volcano on the Southwest Coast of the Kenai Peninsula, Lower Cook Inlet Alaska

    Science.gov (United States)

    Maharrey, J. Z.; Beget, J. E.; Wallace, K.

    2014-12-01

    Augustine Volcano, a small island volcano located in Cook Inlet, Alaska has produced approximately 11 flank-failure debris-avalanches over the last 2,000 yrs (BP) that were large enough to reach the coast of the island and enter the sea. Each debris avalanche conceivably could have triggered a tsunami. In 1883, a tsunami generated by an eruption and flank-failure of Augustine inundated the indigenous Alaskan village of Nanwalek (previously English Bay) with 8 meters of runup. Nanwalek is geographically located atop a coastal headland on the southwest coast of the Kenai Peninsula approximately 85 kilometers due east of Augustine (Beget et al., 2008). Current research in Nanwalek is focused on describing a peat exposure situated on the shoreward edge of the English Bay headland. We present new data from this locality on the sedimentology, tephrochronology, radiocarbon dating, and field stratigraphy. The exposure is basally dated to approximately 7,100 yr BP and includes exotic units of volcanic ash, sand, and gravel. We correlate 19 tephra layers to late Holocene eruptions of Augustine and several Cook Inlet and northern Alaska Peninsula volcanoes. We interpret the non-volcanic clastic sediment horizons in the peat as prehistoric tsunami-inundation events of the English Bay headland. Augustine volcanic-ash deposits found within the tsunami deposits allow correlation to prehistoric coeval flank-failure debris-avalanche deposits exposed on Augustine (Waitt and Beget, 2009). We correlate three tsunami deposits associated with Augustine tephra marker horizons H, I, and G of Waitt and Beget (2009) each of which were erupted approximately 1,400 yr BP, 1,700 yr BP, and 2,100 yr BP. Additionally, we present new tephra and sedimentological evidence for a 4,100 yr BP paleo-tsunami inundation event at Nanwalek that we correlate to a previously unidentified flank-failure debris-avalanche event at Augustine Volcano. The recognition of this new deposit extends the age record for

  7. Ellipsometry and electronic microscopy of ashes swept of the Popocatepetl volcano; Elipsometria y microscopia electronica de barrido de las cenizas del volcan Popocatepetl

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, Aaron; Munoz, Rafel; Falcon, Nelson [Universidad de Carabobo, Valencia (Venezuela); Chavira, Enrique [Instituto Nacional de Astrofisica Optica y Electronica, Puebla (Mexico)

    2001-12-01

    The ellipsometry and the scanning electronic microscopy is applied to the study of the optic properties of Popocatepetl volcano ash in connection with the form, ruggedness and elemental chemical composition of the microparticles, also to argue about the relation with atmospheric conditions. [Spanish] Se aplica la eliposometria y la microscopia electronica de barrido al estudio de las propiedades opticas de las cenizas de volcan Popocatepetl en relacion con la forma, rugosidad y composicion quimica elemental de las microparticulas, destacandose su vinculacion con las condiciones de visibilidad.

  8. Volcanic-ash hazard to aviation during the 2003-2004 eruptive activity of Anatahan volcano, Commonwealth of the Northern Mariana Islands

    Science.gov (United States)

    Guffanti, M.; Ewert, J.W.; Gallina, G.M.; Bluth, G.J.S.; Swanson, G.L.

    2005-01-01

    Within the Commonwealth of the Northern Mariana Islands (CNMI), Anatahan is one of nine active subaerial volcanoes that pose hazards to major air-traffic routes from airborne volcanic ash. The 2003-2004 eruptive activity of Anatahan volcano affected the region's aviation operations for 3 days in May 2003. On the first day of the eruption (10 May 2003), two international flights from Saipan to Japan were cancelled, and several flights implemented ash-avoidance procedures. On 13 May 2003, a high-altitude flight through volcanic gas was reported, with no perceptible damage to the aircraft. TOMS and MODIS analysis of satellite data strongly suggests that no significant ash and only minor amounts of SO2 were involved in the incident, consistent with crew observations. On 23 May 2003, airport operations were disrupted when tropical-cyclone winds dispersed ash to the south, dusting Saipan with light ashfall and causing flight cancellations there and at Guam 320 km south of the volcano. Operational (near-real-time) monitoring of ash clouds produced by Anatahan has been conducted since the first day of the eruption on 10 May 2003 by the Washington Volcanic Ash Advisory Center (VAAC). The VAAC was among the first groups outside of the immediate area of the volcano to detect and report on the unexpected eruption of Anatahan. After being contacted about an unusual cloud by National Weather Service forecasters in Guam at 1235 UTC on 10 May 2003, the VAAC analyzed GOES 9 images, confirming Anatahan as the likely source of an ash cloud and estimating that the eruption began at about 0730 UTC. The VAAC issued its first Volcanic Ash Advisory for Anatahan at 1300 UTC on 10 May 2003 more than 5 h after the start of the eruption, the delay reflecting the difficulty of detecting and confirming a surprise eruption at a remote volcano with no in situ real-time geophysical monitoring. The initial eruption plume reached 10.7-13.4 km (35,000-44,000 ft), well into jet cruise altitudes

  9. Application of a new multiphase multicomponent volcanic conduit model with magma degassing and crystallization to Stromboli volcano.

    Science.gov (United States)

    La Spina, Giuseppe; Burton, Mike; de'Michieli Vitturi, Mattia

    2014-05-01

    Volcanoes exhibit a wide range of eruption styles, from relatively slow effusive eruptions, generating lava flows and lava domes, to explosive eruptions, in which very large volumes of fragmented magma and volcanic gas are ejected high into the atmosphere. During an eruption, much information regarding the magma ascent dynamics can be gathered: melt and exsolved gas composition, crystal content, mass flow rate and ballistic velocities, to name just a few. Due to the lack of direct observations of the conduit itself, mathematical models for magma ascent provide invaluable tools for a better comprehension of the system. The complexity of the multiphase multicomponent gas-magma-solid system is reflected in the corresponding mathematical model; a set of non-linear hyperbolic partial differential and constitutive equations, which describe the physical system, has to be formulated and solved. The standard approach to derive governing equations for two-phase flow is based on averaging procedures, which leads to a system of governing equations in the form of mass, momentum and energy balance laws for each phase coupled with algebraic and differential source terms which represent phase interactions. For this work, we used the model presented by de' Michieli Vitturi et al. (EGU General Assembly Conference Abstracts, 2013), where a different approach based on the theory of thermodynamically compatible systems has been adopted to write the governing multiphase equations for two-phase compressible flow (with two velocities and two pressures) in the form of a conservative hyperbolic system of partial differential equations, coupled with non-differential source terms. Here, in order to better describe the multicomponent nature of the system, we extended the model adding several transport equations to the system for different crystal components and different gas species, and implementing appropriate equations of state. The constitutive equations of the model are chosen to

  10. The ocean response to volcanic iron fertilisation after the eruption of Kasatochi volcano: a regional-scale biogeochemical ocean model study

    Directory of Open Access Journals (Sweden)

    A. Lindenthal

    2013-06-01

    Full Text Available In high-nutrient–low-chlorophyll regions, phytoplankton growth is limited by the availability of water-soluble iron. The eruption of Kasatochi volcano in August 2008 led to ash deposition into the iron-limited NE Pacific Ocean. Volcanic ash released iron upon contact with seawater and generated a massive phytoplankton bloom. Here we investigate this event with a one-dimensional ocean biogeochemical column model to illuminate the ocean response to iron fertilisation by volcanic ash. The results indicate that the added iron triggered a phytoplankton bloom in the summer of 2008. Associated with this bloom, macronutrient concentrations such as nitrate and silicate decline and zooplankton biomass is enhanced in the ocean mixed layer. The simulated development of the drawdown of carbon dioxide and increase of pH in surface seawater is in good agreement with available observations. Sensitivity studies with different supply dates of iron to the ocean emphasise the favourable oceanic conditions in the NE Pacific to generate massive phytoplankton blooms in particular during July and August in comparison to other months. By varying the amount of volcanic ash and associated bio-available iron supplied to the ocean, model results demonstrate that the NE Pacific Ocean has higher, but limited capabilities to consume CO2 after iron fertilisation than those observed after the volcanic eruption of Kasatochi.

  11. Particle morphologies and formation mechanisms of fine volcanic ash aerosol collected from the 2006 eruption of Augustine Volcano, Alaska

    Science.gov (United States)

    Rinkleff, P. G.; Cahill, C. F.

    2010-12-01

    Fine volcanic ash aerosol (35-0.09um) erupted in 2006 by Augustine Volcano, southwest of Anchorage, Alaska was collected by a DRUM cascade impactor and analyzed by scanning electron microscopy for individual particle chemistry and morphology. Results of these analyses show ash particles occur as either individual glass shard and mineral phase (plagioclase, magnetite, ilmenite, hornblende, etc.) particles or aggregates thereof. Individual glass shard ash particles are angular, uniformly-sized, consist of calc-alkaline whole-rock elements (Si, Al, Fe, Na, and Ca) and are not collocated on the sample media with non-silicate, Cl and S bearing sea salt particles. Aggregate particles occur as two types: pure ash aggregates and sea salt-cored aggregates. Pure ash aggregates are made up of only ash particles and contain no other constituents. Sea salt-cored aggregates are ash particles commingled with sea salts. Determining the formation processes of the different ash particle types need further investigation but some possibilities are proposed here. Individual ash particles may exist when the ambient air is generally dry, little electrical charge exists on ash particles, the eruptive cloud is generally dry, or the number of individual particles exceeds the scavenging capacity of the water droplets present. Another possibility is that ash aggregates may break apart as relative humidity drops over time and causes ash-laden water droplets to evaporate and subsequently break apart. Pure ash aggregates may form when the ambient air and plume is relatively dry but the ash has a significant charge to cause ash to aggregate. Or they could form during long-range transport when turbulent or Brownian motion can cause ash particles to collide and coagulate. Pure ash aggregates could also form as a result of water droplet scavenging and subsequent evaporation of water droplets, leaving behind only ash. In this case, droplets would not have interacted with a sea salt

  12. Evolution of {sup 222} Rn and chemical species related with eruptive processes of the Popocatepetl volcano; Evolucion de {sup 222} Rn y especies quimicas relacionadas con procesos eruptivos del volcan Popocatepetl

    Energy Technology Data Exchange (ETDEWEB)

    Aranda, P.; Ceballos, S.; Cruz, D.; Hernandez, A.; Lopez, R.; Pena, P.; Salazar, S.; Segovia, N.; Tamez, E. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The {sup 222} Rn monitoring in the Popocatepetl volcano was initiated on 1993. At December 21, 1994 it is initiated an eruptive stage in the volcano with gas emission, ashes and the lava dome formation on the crater at middle 1996. During all this time it has been determined radon concentrations on soils with active and passive detectors. In this work the changes in radon contents are reported also the physicochemical parameters in spring water related with the volcanic building associated to the recent activity of the volcano. (Author)

  13. About the use of radon in the surveillance of volcanoes from Central America; De l`utilisation du radon dans la surveillance des volcans d`amerique centrale

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, E. [Obviscori, Heridia (Costa Rica); Garcia Vindas, R.; Monnin, M.; Seidel, J.L. [Centre National de la Recherche Scientifique (CNRS), 34 -Montpellier (France). Centre d`Etudes Phytosociologiques et Ecologiques Louis-Emberger; Segovia, N. [ININ, Mexico (Mexico)

    1996-12-31

    Anomalous fluctuations of radon content in soil gases, fumaroles or thermal sources associated with volcanic systems are considered as precursors of deep degassing phenomena. Radon measurements in soil gases were performed for several years on three active volcanoes of Costa-Rica (Arenal, Irazu, Poas), also on El Chichon and Colima volcanoes in Mexico and more recently on the Popocatepetl since its reactivation in December 1994. Data acquisition was initially performed using plastic detectors with a 15 days integration. Since 1993, autonomous automatic probes are used and give hourly measurements. A nine stations network for ground measurements is installed on the Poas since 1982. Radon and Cl{sup -}, F{sup -} and SO{sub 4}{sup 2-} variations of the main crater lake are examined and correlated with the volcanic activity which led to the decay and disappearing of the lake in April 1989. On the Irazu, five stations were installed in 1982 and 3 automatic ones were added in November 1993. Results obtained so far are discussed according to the phreatic eruption of December 1994. The Popocatepetl measurements obtained since December 1994 are presented too. Abstract only. (J.S.).

  14. From high quality seismic data acquisition in remote volcanic area to fast data distribution to scientific community: The UnderVolc project on Piton de la Fournaise volcano

    Science.gov (United States)

    Brenguier, Florent; Kowalski, Philippe; Pequegnat, Catherine; Lauret, Frédéric; Cougoulat, Glenn; Boissier, Patrice; Catherine, Philippe

    2010-05-01

    Piton de la Fournaise basaltic volcano (La Réunion island, France) is one of the most active volcano in the world with an average of one eruption every year. This volcano is thus an ideal case study for research projects focusing on studying magmatic, seismic and deformation processes occurring in volcanic areas. The UNDERVOLC (UNDERstanding VOLCanic Processes) research project main goal is to provide high quality 3-component broadband continuous seismic data to an amount of about 30 volcano-seismologists from different international research teams (including Japan and New-Zealand). This data acquisition system is moreover dedicated to the monitoring of Piton de la Fournaise volcano by providing real-time seismic data to the Piton de la Fournaise volcanological Observatory/IPGP. The network consists of 21 fully autonomous stations composed of CMG40-T seismometers associated to high dynamic digitizers and linked to wireless digital radio stations. The seismic signal is sent by UDP protocol to the observatory through a network of wireless LAN over large distances (~10 km) and possibly through the internet to the Observatory. The acquisition system at the observatory is composed of: 1-An Earthworm system (USGS - ISTI - CERI) with a Q330 to Earthworm data acquisition module (6 permanent stations from the observatory) 2-An Apollo server system (Nanometrics) for 15 stations (for which seismometers and digitizers belong to the French national pool of portable seismic instruments Sismob, INSU-CNRS) In both case, requests are sent back to the stations in case of loss of udp packets. This system allows us producing miniseed files every hour. Since September 2009, the full dataset has less then 1 % of gaps. In order to provide a fast data access to the scientific community, we synchronize our dataset every night with the SISMOB datacenter located in France (LGIT, Grenoble). After a quality check, seed data volumes are produced and distributed by standard NETDC requests from

  15. High Resolution Aircraft Scanner Mapping of Geothermal and Volcanic Areas

    Energy Technology Data Exchange (ETDEWEB)

    Mongillo, M.A.; Cochrane, G.R.; Wood, C.P.; Shibata, Y.

    1995-01-01

    High spectral resolution GEOSCAN Mkll multispectral aircraft scanner imagery has been acquired, at 3-6 m spatial resolutions, over much of the Taupo Volcanic Zone as part of continuing investigations aimed at developing remote sensing techniques for exploring and mapping geothermal and volcanic areas. This study examined the 24-band: visible, near-IR (NIR), mid-IR (MIR) and thermal-IR (TIR) imagery acquired over Waiotapu geothermal area (3 m spatial resolution) and White Island volcano (6 m resolution). Results show that color composite images composed of visible and NIR wavelengths that correspond to color infrared (CIR) photographic wavelengths can be useful for distinguishing among bare ground, water and vegetation features and, in certain cases, for mapping various vegetation types. However, combinations which include an MIR band ({approx} 2.2 {micro}m) with either visible and NIR bands, or two NIR bands, are the most powerful for mapping vegetation types, water bodies, and bare and hydrothermally altered ground. Combinations incorporating a daytime TIR band with NIR and MIR bands are also valuable for locating anomalously hot features and distinguishing among different types of surface hydrothermal alteration.

  16. A geochemical comparison of alkalic lavas in the Trans-Mexican Volcanic Belt, peninsular Baja California and intraplate volcanoes in the eastern Pacific

    Science.gov (United States)

    Tian, L.; Castillo, P. R.

    2011-12-01

    The Trans-Mexican Volcanic Belt (TMVB) is a continental volcanic arc built along the southern edge of the North American plate. The volcanic rocks along TMVB are compositionally diverse and the origin of its alkalic lavas with ocean island basalt (OIB)-like composition is highly controversial. Alkalic lavas from four regions in the western, central, and eastern TMVB [e.g., Verma and Hasenaka, Geochem. J., 58, 2004; Petrone et al., Geol. S. Am. S., 402, 2006; Orozco-Esquivel et al., Geol. Soc. Amer. Bull., 93, 2007] are compared with similar OIB-like alkalic lavas from peninsular Baja California [e.g., Storey et al., Terra Nova, 1, 1989; Castillo, Geol. Soc. Amer. Bull., 120, 2008] and intraplate volcanoes in the eastern Pacific [Tian et al., Geochem. Geophys. Geosyst., 12, 2011] in order to ascertain their geochemical similarities and differences and to constrain the compositions of their respective magma sources. A few of the alkalic lavas from TMVB have very similar trace element and isotopic compositions as the OIB-like alkalic lavas from peninsular Baja California and intraplate volcanoes in the eastern Pacific. Majority of the TMVB alkalic lavas, however, are compositionally more heterogeneous, similar to the less-alkalic Nb-enriched basalts in peninsular Baja California representing OIB-like alkalic lavas that had been contaminated by other mantle components and/or crustal materials. Thus, data seem to indicate that all the OIB-like alkalic lavas can be traced to a similar source, the compositionally heterogeneous Pacific asthenosphere.

  17. Constraints on the timing of Quaternary volcanism and duration of magma residence at Ciomadul volcano, east-central Europe, from combined U-Th/He and U-Th zircon geochronology

    Science.gov (United States)

    Harangi, S.; Lukács, R.; Schmitt, A. K.; Dunkl, I.; Molnár, K.; Kiss, B.; Seghedi, I.; Novothny, Á.; Molnár, M.

    2015-08-01

    High-spatial resolution zircon geochronology was applied to constrain the timescales of volcanic eruptions of the youngest, mostly explosive volcanic phase of Ciomadul volcano (Carpathian-Pannonian region, Romania). Combined U-Th and (U-Th)/He zircon dating demonstrates that intermittent volcanic eruptions occurred in a time range of 56-32 ka. The reliability of the eruption dates is supported by concordant ages obtained from different dating techniques, such as zircon geochronology, radiocarbon analysis, and infrared stimulated luminescence dating for the same deposits. The new geochronological data suggest that volcanism at Ciomadul is much younger (volcanic phase occurred after an apparent lull in volcanism that lasted for several 10's of ka, after a period of lava dome extrusion that defines the onset of the known volcanism at Ciomadul. At least four major eruptive episodes can be distinguished within the 56-32 ka period. Among them, relatively large (sub-plinian to plinian) explosive eruptions produced distal tephra covering extended areas mostly southeast from the volcano. The 38.9 ka tephra overlaps the age of the Campanian Ignimbrite eruption and has an overlapping dispersion axis towards the Black Sea region. The wide range of U-Th model ages of the studied zircons indicates prolonged existence of a low-temperature (volcanism. Even the youngest U-Th model ages obtained for the outermost 4 μm rim of individual zircon crystals predate the eruption by several 10's of ka. The zircon age distributions suggest re-heating above zircon saturation temperatures via injection of hot mafic magmas prior to eruption. Intermittent intrusions of fresh magma could play a significant role in keeping the intrusive silicic magmatic reservoir in a partially melted for prolonged period. The previous history of Ciomadul suggests that melt-bearing crystal mush resided beneath the volcano, and was rapidly remobilized after a protracted (several 10's of ka) lull in volcanism to

  18. Mineralogical study on volcanic ash of the eruption on September 27, 2014 at Ontake volcano, central Japan: correlation with porphyry copper systems

    Science.gov (United States)

    Minami, Yusuke; Imura, Takumi; Hayashi, Shintaro; Ohba, Tsukasa

    2016-04-01

    The volcanic ash of the eruption on September 27, 2014 at Ontake volcano consists mostly of altered rock fragments. The ash contains partly altered volcanic rock fragments consisting of primary igneous minerals (plagioclase, orthopyroxene, titanomagnetite, and feldspars) and volcanic glass accompanied by alteration minerals to some extents, and contains no juvenile fragments. These features indicate that the eruption was a non-juvenile hydrothermal eruption that was derived from the hydrothermal system developed under the crater. The major minerals derived from hydrothermal alteration zones are silica mineral, kaolin-group mineral, smectite, pyrophyllite, muscovite, alunite, anhydrite, gypsum, pyrite, K-feldspar, albite, and rutile. Minor chlorite, biotite, and garnet are accompanied. Five types of alteration mineral associations are identified from observations on individual ash particles: silica-pyrite, silica-pyrite ± alunite ± kaolin, silica-pyrophyllite-pyrite, silica-muscovite ± chlorite, and silica-K-feldspar ± albite ± garnet ± biotite. The associations indicate development of advanced argillic, sericite, and potassic alteration zones under the crater. Occurrence of anhydrite veinlet and the set of alteration zones indicate hydrothermal alteration zones similar to late-stage porphyry copper systems. Comparing the mineral associations with the geologic model of the late-stage porphyry copper systems, the source depths of mineral associations are estimated to range from near surface to >2 km. The depths of advanced argillic alteration, sericite, and potassic zones are 0 to ~2, ~1.5 to ~2, and >2 km, respectively.

  19. A new simplified approach for simultaneous retrieval of SO2 and ash content of tropospheric volcanic clouds: an application to the Mt Etna volcano

    Directory of Open Access Journals (Sweden)

    S. Pugnaghi

    2013-05-01

    Full Text Available A new procedure is presented for simultaneous estimation of SO2 and ash abundance in a volcanic plume, using thermal infrared (TIR MODIS data. Plume altitude and temperature are the only two input parameters required to run the procedure, while surface emissivity, temperature, atmospheric profiles, ash optical properties, and radiative transfer models are not necessary to perform the atmospheric corrections. The procedure gives the most reliable results when the surface under the plume is uniform, for example above the ocean, but still produces fairly good estimates in more challenging and not easily modelled conditions, such as above land or meteorological cloud layers. The developed approach was tested on the Etna volcano. By linearly interpolating the radiances surrounding a detected volcanic plume, the volcanic plume removal (VPR procedure described here computes the radiances that would have been measured by the sensor in the absence of a plume, and reconstructs a new image without plume. The new image and the original data allow computation of plume transmittance in the TIR-MODIS bands 29, 31, and 32 (8.6, 11.0 and 12.0 μm by applying a simplified model consisting of a uniform plume at a fixed altitude and temperature. The transmittances are then refined with a polynomial relationship obtained by means of MODTRAN simulations adapted for the geographical region, ash type, and atmospheric profiles. Bands 31 and 32 are SO2 transparent and, from their transmittances, the effective ash particle radius (Re, and aerosol optical depth at 550 nm (AOD550 are computed. A simple relation between the ash transmittances of bands 31 and 29 is demonstrated and used for SO2 columnar content (cs estimation. Comparing the results of the VPR procedure with MODTRAN simulations for more than 200 000 different cases, the frequency distribution of the differences shows the following: the Re error is less than ±0.5 μm in more than 60% of cases; the AOD550 error

  20. The impact of rapid recharge events on the evolution of magma chambers: Case studies of Santorini Volcano (Greece) and Volcan Quizapu (Chile)

    Science.gov (United States)

    Degruyter, Wim; Huber, Christian; Bachmann, Olivier; Cooper, Kari; Kent, Adam

    2016-04-01

    Magma reservoirs in the crust are thought to be dominantly formed by episodic recharge events at rates that are much larger than the long-term average magma inflow rates. Hence, a better understanding of the evolution of a magma reservoir requires elucidating the mass change, pressurization, heating, deformation and the potential for an eruption associated with different recharge scenarios. Most importantly, the bifurcation in behavior between a recharge event that leads to eruption and one that will grow the chamber requires quantification for better volcanic hazard assessment. We use a numerical model to determine the change in pressure, temperature and volume of a magma chamber as it is exposed to a recharge event. The model is applied to the well-studied volcanic systems of Santorini Volcano (Greece) and Volcan Quizapu (Chile). We establish the rates and the duration of magma recharge events that will lead to an eruption. In doing so, we demonstrate the importance of the state of the magma chamber prior to the recharge event, i.e. its size and exsolved volatile content, on the subsequent evolution of the reservoir. In the case of Santorini, the model successfully reproduces the main features of the Minoan eruption and Nea Kameni activity, providing volume estimates for the active part of the current subvolcanic reservoir as well as information regarding the presence of exsolved volatiles. For Quizapu, we suggest that the change in eruptive style, from an effusive outpouring of lava in 1846-1847 to an explosive Plinian eruption in 1932, was controlled by a shift in the state of the magma chamber induced by the first eruption. These case studies show that thermo-mechanical models offer a new framework to integrate the historic eruption record with geodetic measurements and provide a context to understand the past, present and future of active volcanic centers.

  1. The Albano maar lake (Colli Albani Volcano, Italy): recent volcanic activity and evidence of pre-Roman Age catastrophic lahar events

    Science.gov (United States)

    Funiciello, R.; Giordano, G.; De Rita, D.

    2003-04-01

    The evaluation of volcanic hazard in the Roman hinterland related to the quiescent Colli Albani Volcano has recently been the subject of renewed attention and several interpretations by many authors. However, very little was known of the recent history of the volcano, making such interpretations rather speculative. The most recent activity of Colli Albani Volcano originated from the Albano polygenetic maar lake, which erupted several phreatomagmatic units, the most recent of which, the Peperino Albano ignimbrite, has been dated at around 25 ka. An area of several square kilometers centered around Albano Lake is presently the site of shallow and frequent seismic activity and gaseous emission as well as hydrothermal activity and is therefore considered the most prone to geologic hazards. This paper presents new stratigraphic and geomorphologic data as well as age determinations that allow rejuvenation of the most recent activity of the Colli Albani Volcano, and particularly the Albano maar lake, to the Holocene. This study allows for the first time to identify a potential hazard related to the Albano maar lake withdrawal interpreted to be related to endogenous causes, namely CO 2 emission. The main results of the study are: (1) the Peperino Albano is not, as is generally believed, the last phreatomagmatic eruption from the Colli Albani Volcano; a previously unrecognized phreatomagmatic surge deposit has been identified overlying the paleosol at the top of the Peperino Albano and related lahar deposits; (2) two lahar deposits separated by paleosols top the stratigraphic succession and are dispersed only to the NW, corresponding to the lowest point of the maar rim, indicating that catastrophic hydrologic events occurred at the Albano Lake in recent times; rapid and substantial lake-level variations and lake withdrawal are reported by Roman historians and recorded by the stratigraphy of the Albano Lake lacustrine sediments; (3) microfracturing related to seismic energy

  2. Geology and geochemistry of Pelagatos, Cerro del Agua, and Dos Cerros monogenetic volcanoes in the Sierra Chichinautzin Volcanic Field, south of México City

    Science.gov (United States)

    Agustín-Flores, Javier; Siebe, Claus; Guilbaud, Marie-Noëlle

    2011-04-01

    This study focuses on the geology and geochemistry of three closely-spaced monogenetic volcanoes that are located in the NE sector of the Sierra Chichinautzin Volcanic Field near México City. Pelagatos (3020 m.a.s.l.) is a small scoria cone (0.0017 km 3) with lava flows (0.036 km 3) that covered an area of 4.9 km 2. Cerro del Agua scoria cone (3480 m.a.s.l., 0.028 km 3) produced several lava flows (0.24 km 3) covering an area of 17.6 km 2. Dos Cerros is a lava shield which covers an area of 80.3 km 2 and is crowned by two scoria cones: Tezpomayo (3080 m.a.s.l., 0.022 km 3) and La Ninfa (3000 m.a.s.l., 0.032 km 3). The eruptions of Cerro del Agua and Pelagatos occurred between 2500 and 14,000 yr BP. The Dos Cerros eruption took place close to 14,000 yr BP as constrained by radiocarbon dating. Rocks from these three volcanoes are olivine-hypersthene normative basaltic andesites and andesites with porphyritic, aphanitic, and glomeroporphyritic textures. Their mineral assemblages include olivine, clinopyroxene, and orthopyroxene phenocrysts (≤ 10 vol.%) embedded in a trachytic groundmass which consists mainly of plagioclase microlites and glass. Pelagatos rocks also present quartz xenocrysts. Due to their high Cr and Ni contents, and high Mg#s, Pelagatos rocks are considered to be derived from primitive magmas, hence the importance of this volcano for understanding petrogenetic processes in this region. Major and trace element abundances and petrography of products from these volcanoes indicate a certain degree of crystal fractionation during ascent to the surface. However, the magmas that formed the volcanoes evolved independently from each other and are not cogenetically related. REE, HFSE, LILE, and isotopic (Sr, Nd, and Pb) compositions point towards a heterogeneous mantle source that has been metasomatized by aqueous/melt phases from the subducted Cocos slab. There is no clear evidence of important crustal contributions in the compositions of Pelagatos and

  3. Tectonic evolution of the central-eastern sector of Trans Mexican Volcanic Belt and its influence on the eruptive history of the Nevado de Toluca volcano (Mexico)

    Science.gov (United States)

    Bellotti, F.; Capra, L.; Groppelli, G.; Norini, G.

    2006-11-01

    The Nevado de Toluca is an andesitic to dacitic stratovolcano of Late Pliocene-Holocene age located within the central and eastern sectors of the Trans Mexican Volcanic Belt. Morphostructural analysis, aerial photograph and satellite image interpretation, structural analysis and geological fieldwork were methods used to investigate the relationship between the evolution of the volcano and the tectonic framework of its basement. The study revealed that the area of Nevado de Toluca is affected by three main fault systems that intersect close to the volcanic edifice. These are from oldest to youngest, the Taxco-Querétaro, San Antonio and Tenango fault systems. The NNW-SSE Taxco-Querétaro fault system was active in the area since Early Miocene, and is characterized by right-lateral transtensive movement. Its reactivation during Early to Middle Pleistocene was responsible for the emplacement of andesitic to dacitic lava flows and domes of La Cieneguilla Supersynthem. The NE-SW San Antonio fault system was active during Late Pliocene, before the reactivation of the Taxco-Querétaro fault system, and is characterized by extensional left-lateral oblique-slip kinematics. The youngest is the E-W Tenango fault system that has been active since Late Pleistocene. This fault system is characterized by transtensive left-lateral strike-slip movement, and partly coeval with the youngest eruptive phase, the Nevado Supersynthem, which formed the present summit cone of the Nevado de Toluca volcano. The stress re-orientation from the Taxco-Querétaro to the Tenango fault system during Late Pleistocene is responsible for the ˜ 1 Ma hiatus in the magmatic activity between 1.15 Ma and 42 ka. After this period of repose, the eruptive style drastically changed from effusive to explosive with the emission of dacitic products. The methodology presented here furnish new data that can be used to better assess the complex structural evolution of this sector of the Trans Mexican Volcanic Belt

  4. Geochemical evolution of the acid crater lake of Poas volcano (Costa Rica): Insights into volcanic-hydrothermal processes

    NARCIS (Netherlands)

    Martínez Cruz, María

    2008-01-01

    This thesis describes the evolution of Laguna Caliente, an acid crater lake at the summit of Po:is, a persistently active volcano in central Costa Rica. The appearance, volume, temperature and chemical composition of the lake have continuously changed over the entire known period of its existence. O

  5. Long-Term Volcanic Activity at Shiveluch Volcano: Nine Years of ASTER Spaceborne Thermal Infrared Observations  

    Directory of Open Access Journals (Sweden)

    Adam Carter

    2010-11-01

    Full Text Available Shiveluch (Kamchatka, Russia is the most active andesitic volcano of the Kuril-Kamchatka arc, typically exhibiting near-continual high-temperature fumarolic activity and periods of exogenous lava dome emplacement punctuated by discrete large explosive eruptions. These eruptions can produce large pyroclastic flow (PF deposits, which are common on the southern flank of the volcano. Since 2000, six explosive eruptions have occurred that generated ash fall and PF deposits. Over this same time period, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER instrument has been acquiring image-based visible/near infrared (VNIR, short wave infrared (SWIR and thermal infrared (TIR data globally, with a particular emphasis on active volcanoes. Shiveluch was selected as an ASTER target of interest early in the mission because of its frequent activity and potential impact to northern Pacific air transportation. The north Pacific ASTER archive was queried for Shiveluch data and we present results from 2000 to 2009 that documents three large PF deposits emplaced on 19 May 2001, 9 May 2004, and 28 February 2005. The long-term archive of infrared data provides an excellent record on the changing activity and eruption state of the volcano.

  6. Geomorphological evolution of volcanic fluvial channels: Eighteen years of morphological monitoring of the upper strect of the Tenenepanco Gorge, Popocatépetl volcano, Mexico

    Science.gov (United States)

    Tanarro, Luis Miguel; Juan Zamorano, Jose; Andres, Nuria; Palacios, David

    2015-04-01

    During volcanic eruptions a significant volume of material accumulates on the slopes and pre-existing gorges of the stratovolcanoes. This abundance of loose and unconsolidated material is very likely to be mobilized by rapid flows or lahars generated by sudden heavy rain or melting snow and ice. Thus, volcanic gorges are affected by complex cycles of incision, filling and widening, altering the equilibrium of river systems due to the major changes that lahars cause in channel morphology. These geomorphological dynamics characterize the gorges located on the north flank of the Popocatépetl volcano (19°02' N, 98°62' W, 5424 m). This volcano, located in the centre of the Trans-Mexican Volcanic Belt, began its most recent eruptive period in December 1994, when a glacier partially covered the northern slope. Since then, the interaction of volcanic and glacier activity triggered the formation of lahars in the gorges, causing significant morphological changes in the channel (especially in April 1995, July 1997 and January 2001). The most recent major eruption at Popocatépetl took place on 19 July 2003, and since then a series of smaller eruptions has reduced the glacier to near extinction. The aim of this study is to assess the morphological response of the Tenenepanco channel over an 18-year period, from 1995-2013, where two main scenarios can be observed: a) the period from 1995 to 2001 of volcanic activity and glacier retreat with the formation of flows and b) the period from 2002 to 2013 of relative volcanic calm, the almost complete extinction of the glacier, and the formation of secondary lahars associated with heavy rainfall. Monitoring of the gorge has consisted in the elaboration of 14 geomorphological maps during field studies (November 14, 1995, December 5, 1997, February 7, 1998, October 6, 2001, November 14, 1995, December 5, 1997, February 7, 1998, October 6, 2001, Julio 16, 2002, February 11, 2004, September 8, 2004, February 5, 2006, November 2, 2008

  7. The memory of volcanic waters: Shallow magma degassing revealed by halogen monitoring in thermal springs of La Soufrière volcano (Guadeloupe, Lesser Antilles)

    Science.gov (United States)

    Villemant, Benoît; Hammouya, Gilbert; Michel, Agnès; Semet, Michel P.; Komorowski, Jean-Christophe; Boudon, Georges; Cheminée, Jean-Louis

    2005-09-01

    The halogen contents of thermal waters collected since 1979 at La Soufrière volcano (Guadeloupe, Lesser Antilles) are interpreted as a retarded record of magma degassing pulses dispersed into the hydrothermal system. The further the spring is located from the source, the larger the time delay and the older the event recorded in water chemistry. Using advection-dispersion transport models in porous media, we reconstruct the time-series of degassing pulses for the period 1971-1992 and show that it correlates with the seismic records. The 1975-1977 sismo-volcanic crisis at La Soufrière is thereby interpreted as the result of a magma intrusion at shallow depth (˜3 km) which likely began in approximately 1973 and degassed in a pulsatory regime during ˜15 yr. The recent recrudescence of fumarolic and seismic activity could represent the initial stage of new magma injection. Measurement of halogen contents in hydrothermal waters collected around active volcanoes may provide a powerful tool for detection of the initial stages of magma intrusions.

  8. Thermal mapping: the hydrothermal system of a volcano used to map faults and palaeostructures within stratified ground. The Yasur-Yenkahe volcanic complex (Vanuatu)

    Science.gov (United States)

    Amin Douillet, Guilhem; Peltier, Aline; Finizola, Anthony; Brothelande, Elodie; Garaebiti, Esline

    2014-05-01

    Subsurface thermal measurements provide a valuable tool to map hydrothermal-fluid release zones in activevolcanic areas. On explosive volcanoes, where ash fall layers deposit parallel to the ground surface, hydrothermal fluids are trapped in the stratification due to the variations in permeability in deposits of the different explosive phases. Thermal fluids thus travel parallel to the surface close to the ground. This horizontal flux can only escape when faults break the seals of stratification. On the Yasur-Yenkahe volcanic complex (Tanna Island, Vanuatu archipelago), fumaroles andhot springs abound, signs of upraising heat fluxes associated to a well-developed hydrothermal activity. Combinationof high resolution mapping of ground thermal anomalies with geomorphological analysis allows thecharacterization of the structural relationships between the active Yasur volcano and the Yenkahe resurgent dome. A complex system of heat release and hydrothermal fluid circulation below the Yasur-Yenkahe complex isevidenced. Circulation, though propagating vertically as a whole, is funneled by stratification. Thus, the main thermal fluid release is almost exclusively concentrated along structural limits that break the seals inducedby the stratified nature of the ground. Three types of medium/high temperature anomalies have beenevidenced: (1) broad hydrothermalized areas linked with planar stratification that favor lateral spreading,(2) linear segments that represent active faults, and (3) arcuate segments related to paleo-crater rims. Thelimit between the Yasur volcano and the Yenkahe resurgent dome is characterized by an active fault systemaccommodating both the rapid uplift of the Yenkahe block and the overloading induced by the volcanoweight. In such a setting, faults converge below the cone of Yasur, which acts as a focus for the faults. Evidenceof such structures, sometimes hidden in the landscape but detected by thermal measurements, iscritical for risk assessment of

  9. In Situ Observations and Sampling of Volcanic Emissions with Unmanned Aircraft: A NASA/UCR Case Study at Turrialba Volcano, Costa Rica

    Science.gov (United States)

    Pieri, David; Diaz, Jorge Andres; Bland, Geoffrey; Fladeland, Matthew; Madrigal, Yetty; Corrales, Ernesto; Alan, Alfredo; Alegria, Oscar; Realmuto, Vincent; Miles, Ted

    2011-01-01

    Burgeoning new technology in the design and development of robotic aircraft-unmanned aerial vehicles (UAVs)-presents unprecedented opportunities for the volcanology community to observe, measure, and sample eruption plumes and drifting volcanic clouds in situ. While manned aircraft can sample dilute parts of such emissions, demonstrated hazards to air breathing, and most particularly turbine, engines preclude penetration of the zones of highest ash concentrations. Such areas within plumes are often of highest interest with respect to boundary conditions of applicable mass-loading retrieval models, as well as Lagrangian, Eulerian, and hybrid transport models used by hazard responders to predict plume trajectories, particularly in the context of airborne hazards. Before the 2010 Ejyafyallajokull eruption in Iceland, ICAO zero-ash-tolerance rules were typically followed, particularly for relatively uncrowded Pacific Rim airspace, and over North and South America, where often diversion of aircraft around ash plumes and clouds was practical. The 2010 eruption in Iceland radically changed the paradigm, in that critical airspace over continental Europe and the United Kingdom were summarily shut by local civil aviation authorities and EURO CONTROL. A strong desire emerged for better real-time knowledge of ash cloud characteristics, particularly ash concentrations, and especially for validation of orbital multispectral imaging. UAV platforms appear to provide a viable adjunct, if not a primary source, of such in situ data for volcanic plumes and drifting volcanic clouds from explosive eruptions, with prompt and comprehensive application to aviation safety and to the basic science of volcanology. Current work is underway in Costa Rica at Turrialba volcano by the authors, with the goal of developing and testing new small, economical UAV platforms, with miniaturized instrument payloads, within a volcanic plume. We are underway with bi-monthly deployments of tethered SO2-sondes

  10. Santorini Volcano

    Science.gov (United States)

    Druitt, T.H.; Edwards, L.; Mellors, R.M.; Pyle, D.M.; Sparks, R.S.J.; Lanphere, M.; Davies, M.; Barreirio, B.

    1999-01-01

    Santorini is one of the most spectacular caldera volcanoes in the world. It has been the focus of significant scientific and scholastic interest because of the great Bronze Age explosive eruption that buried the Minoan town of Akrotiri. Santorini is still active. It has been dormant since 1950, but there have been several substantial historic eruptions. Because of this potential risk to life, both for the indigenous population and for the large number of tourists who visit it, Santorini has been designated one of five European Laboratory Volcanoes by the European Commission. Santorini has long fascinated geologists, with some important early work on volcanoes being conducted there. Since 1980, research groups at Cambridge University, and later at the University of Bristol and Blaise Pascal University in Clermont-Ferrand, have collected a large amount of data on the stratigraphy, geochemistry, geochronology and petrology of the volcanics. The volcanic field has been remapped at a scale of 1:10 000. A remarkable picture of cyclic volcanic activity and magmatic evolution has emerged from this work. Much of this work has remained unpublished until now. This Memoir synthesizes for the first time all the data from the Cambridge/Bristol/Clermont groups, and integrates published data from other research groups. It provides the latest interpretation of the tectonic and magmatic evolution of Santorini. It is accompanied by the new 1:10 000 full-colour geological map of the island.

  11. ASTER Urgent Response to the 2006 Eruption of Augustine Volcano, Alaska: Science and Decision Support Gained From Frequent High-resolution, Satellite Thermal Infrared Imaging of Volcanic Events

    Science.gov (United States)

    Wessels, R. L.; Ramsey, M. S.; Schneider, D. S.; Coombs, M.; Dehn, J.; Realmuto, V. J.

    2006-12-01

    Augustine Volcano, Alaska explosively erupted on January 11, 2006 after nearly eight months of increasing seismicity, deformation, gas emission, and small phreatic explosions. The volcano produced a total of 13 explosive eruptions during the last three weeks of January 2006. A new summit lava dome and two short, blocky lava flows grew during February and March 2006. A series of 7 daytime and 15 nighttime Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scenes were acquired in response to this new activity. This response was facilitated by a new ASTER Urgent Request Protocol system. The ASTER data provided several significant observations as a part of a much larger suite of real-time or near-real-time data from other satellite (AVHRR, MODIS), airborne (FLIR, visual, gas), and ground-based (seismometers, radiometers) sensors used at the Alaska Volcano Observatory (AVO). ASTER is well-suited to volcanic observations because of its 15-m to 90-m spatial resolution, its ability to be scheduled and point off-nadir, and its ability to collect visible-near infrared (VNIR) to thermal infrared (TIR) data during both the day and night. Aided by the volcano's high latitude (59.4°N) ASTER was able to provide frequent repeat imaging as short as one day between scenes with an average 6-day repeat during the height of activity. These data provided a time series of high-resolution VNIR, shortwave infrared (SWIR - detects temperatures from about 200°C to > 600°C averaged over a 30-m pixel), and TIR (detects temperatures up to about 100°C averaged over a 90-m pixel) data of the volcano and its eruptive products. Frequent satellite imaging of volcanoes is necessary to record rapid changes in activity and to avoid recurring cloud cover. Of the 22 ASTER scenes acquired between October 30, 2005 and May 30, 2006, the volcano was clear to partly cloudy in 13 scenes. The most useful pre-eruption ASTER Urgent Request image was acquired on December 20. These data

  12. Inverse steptoes in Las Bombas volcano, as an evidence of explosive volcanism in a solidified lava flow field. Southern Mendoza-Argentina

    Science.gov (United States)

    Risso, Corina; Prezzi, Claudia; Orgeira, María Julia; Nullo, Francisco; Margonari, Liliana; Németh, Karoly

    2015-11-01

    Here we describe the unusual genesis of steptoes in Las Bombas volcano- Llancanelo Volcanic Field (LVF) (Pliocene - Quaternary), Mendoza, Argentina. Typically, a steptoe forms when a lava flow envelops a hill, creating a well-defined stratigraphic relationship between the older hill and the younger lava flow. In the Llancanelo Volcanic Field, we find steptoes formed with an apparent normal stratigraphic relationship but an inverse age-relationship. Eroded remnants of scoria cones occur in ;circular depressions; in the lava field. To express the inverse age-relationship between flow fields and depression-filled cones here we define this landforms as inverse steptoes. Magnetometric analysis supports this inverse age relationship, indicating reverse dipolar magnetic anomalies in the lava field and normal dipolar magnetization in the scoria cones (e.g. La Bombas). Negative Bouguer anomalies calculated for Las Bombas further support the interpretation that the scoria cones formed by secondary fracturing on already solidified basaltic lava flows. Advanced erosion and mass movements in the inner edge of the depressions created a perfectly excavated circular depression enhancing the ;crater-like; architecture of the preserved landforms. Given the unusual genesis of the steptoes in LVF, we prefer the term inverse steptoe for these landforms. The term steptoe is a geomorphological name that has genetic implications, indicating an older hill and a younger lava flow. Here the relationship is reversed.

  13. Magma replenishment and volcanic unrest inferred from the analysis of VT micro-seismicity and seismic velocity changes at Piton de la Fournaise Volcano

    Science.gov (United States)

    Brenguier, F.; Rivemale, E.; Clarke, D. S.; Schmid, A.; Got, J.; Battaglia, J.; Taisne, B.; Staudacher, T.; Peltier, A.; Shapiro, N. M.; Tait, S.; Ferrazzini, V.; Di Muro, A.

    2011-12-01

    Piton de la Fournaise volcano (PdF) is among the most active basaltic volcanoes worldwide with more than one eruption per year on average. Also, PdF is densely instrumented with short-period and broad-band seismometers as well as with GPS receivers. Continuous seismic waveforms are available from 1999. Piton de la Fournaise volcano has a moderate inter-eruptive seismic activity with an average of five detected Volcano-Tectonic (VT) earthquakes per day with magnitudes ranging from 0.5 to 3.5. These earthquakes are shallow and located about 2.5 kilometers beneath the edifice surface. Volcanic unrest is captured on average a few weeks before eruptions by measurements of increased VT seismicity rate, inflation of the edifice summit, and decreased seismic velocities from correlations of seismic noise. Eruptions are usually preceded by seismic swarms of VT earthquakes. Recently, almost 50 % of seismic swarms were not followed by eruptions. Within this work, we aim to gather results from different groups of the UnderVolc research project in order to better understand the processes of deep magma transfer, volcanic unrest, and pre-eruptive magma transport initiation. Among our results, we show that the period 1999-2003 was characterized by a long-term increase of VT seismicity rate coupled with a long-term decrease of seismic velocities. These observations could indicate a long-term replenishment of the magma storage area. The relocation of ten years of inter-eruptive micro-seismicity shows a narrow (~300 m long) sub-vertical fault zone thus indicating a conduit rather than an extended magma reservoir as the shallow magma feeder system. Also, we focus on the processes of short-term volcanic unrest and prove that magma intrusions within the edifice leading to eruptions activate specific VT earthquakes that are distinct from magma intrusions that do not lead to eruptions. We thus propose that, among the different pathways of magma transport within the edifice, only one will

  14. Hazard assessment of far-range volcanic ash dispersal from a violent Strombolian eruption at Somma-Vesuvius volcano, Naples, Italy: implications on civil aviation

    Science.gov (United States)

    Sulpizio, Roberto; Folch, Arnau; Costa, Antonio; Scaini, Chiara; Dellino, Pierfrancesco

    2012-11-01

    Long-range dispersal of volcanic ash can disrupt civil aviation over large areas, as occurred during the 2010 eruption of Eyjafjallajökull volcano in Iceland. Here we assess the hazard for civil aviation posed by volcanic ash from a potential violent Strombolian eruption of Somma-Vesuvius, the most likely scenario if eruptive activity resumed at this volcano. A Somma-Vesuvius eruption is of concern for two main reasons: (1) there is a high probability (38 %) that the eruption will be violent Strombolian, as this activity has been common in the most recent period of activity (between AD 1631 and 1944); and (2) violent Strombolian eruptions typically last longer than higher-magnitude events (from 3 to 7 days for the climactic phases) and, consequently, are likely to cause prolonged air traffic disruption (even at large distances if a substantial amount of fine ash is produced such as is typical during Vesuvius eruptions). We compute probabilistic hazard maps for airborne ash concentration at relevant flight levels using the FALL3D ash dispersal model and a statistically representative set of meteorological conditions. Probabilistic hazard maps are computed for two different ash concentration thresholds, 2 and 0.2 mg/m3, which correspond, respectively, to the no-fly and enhanced procedure conditions defined in Europe during the Eyjafjallajökull eruption. The seasonal influence of ash dispersal is also analysed by computing seasonal maps. We define the persistence of ash in the atmosphere as the time that a concentration threshold is exceeded divided by the total duration of the eruption (here the eruption phase producing a sustained eruption column). The maps of averaged persistence give additional information on the expected duration of the conditions leading to flight disruption at a given location. We assess the impact that a violent Strombolian eruption would have on the main airports and aerial corridors of the Central Mediterranean area, and this assessment

  15. Volcanic risk metrics at Mt Ruapehu, New Zealand: some background to a probabilistic eruption forecasting scheme and a cost/benefit analysis at an open conduit volcano

    Science.gov (United States)

    Jolly, Gill; Sandri, Laura; Lindsay, Jan; Scott, Brad; Sherburn, Steve; Jolly, Art; Fournier, Nico; Keys, Harry; Marzocchi, Warner

    2010-05-01

    The Bayesian Event Tree for Eruption Forecasting software (BET_EF) is a probabilistic model based on an event tree scheme that was created specifically to compute long- and short-term probabilities of different outcomes (volcanic unrest, magmatic unrest, eruption, vent location and eruption size) at long-time dormant and routinely monitored volcanoes. It is based on the assumption that upward movements of magma in a closed conduit volcano will produce detectable changes in the monitored parameters at the surface. In this perspective, the goal of BET_EF is to compute probabilities by merging information from geology, models, past data and present monitoring measurements, through a Bayesian inferential method. In the present study, we attempt to apply BET_EF to Mt Ruapehu, a very active and well-monitored volcano exhibiting the typical features of open conduit volcanoes. In such conditions, current monitoring at the surface is not necessarily able to detect short term changes at depth that may occur only seconds to minutes before an eruption. This results in so-called "blue sky eruptions" of Mt Ruapehu (for example in September 2007), that are volcanic eruptions apparently not preceded by any presently detectable signal in the current monitoring. A further complication at Mt Ruapehu arises from the well-developed hydrothermal system and the permanent crater lake sitting on top of the magmatic conduit. Both the hydrothermal system and crater lake may act to mask or change monitoring signals (if present) that magma produces deeper in the edifice. Notwithstanding these potential drawbacks, we think that an attempt to apply BET_EF at Ruapehu is worthwhile, for several reasons. First, with the exception of a few "blue sky" events, monitoring data at Mt Ruapehu can be helpful in forecasting major events, especially if a large amount of magma is intruded into the edifice and becomes available for phreatomagmatic or magmatic eruptions, as for example in 1995-96. Secondly, in

  16. A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity.

    Science.gov (United States)

    Alanis, Paul K B; Yamaya, Yusuke; Takeuchi, Akihiro; Sasai, Yoichi; Okada, Yoshihiro; Nagao, Toshiyasu

    2013-01-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km×3 km×3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano's activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions.

  17. Volcanic gas

    Science.gov (United States)

    McGee, Kenneth A.; Gerlach, Terrance M.

    1995-01-01

    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  18. Determination of concentration of radon, volatile organic compounds (VOC) and water chemistry in springs near to Popocatepetl volcano; Determinacion de la concentracion de radon, VOCs y Quimica del agua en manantiales cercanos al volcan Popocatepetl

    Energy Technology Data Exchange (ETDEWEB)

    Pena, P.; Segovia, N.; Lopez M, B.E.; Cisniega, G. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Valdes, C.; Armienta, M.A.; Mena, M. [Instituto de Geofisica, UNAM, 04510 Mexico D.F. (Mexico)

    2004-07-01

    Popocatepetl volcano is a high-risk active volcano in Central Mexico where the highest population density in the country is settled. Radon in the soil and groundwater together with water chemistry from samples of nearby springs is analysed as a function of the 2002-2003 volcanic activity. Soil radon indicated fluctuations related both the meteorological parameters and sporadic explosive events. Groundwater radon showed essentially differences in concentration due to the specific characteristics of the studied springs. Water chemistry showed stability along the monitoring period indicating also differences between springs. No anthropogenic pollution from volatile organic compounds was observed. (Author)

  19. Chemical and isotopic compositions of thermal springs, fumaroles and bubbling gases at Tacaná Volcano (Mexico-Guatemala): implications for volcanic surveillance

    Science.gov (United States)

    Rouwet, Dmitri; Inguaggiato, Salvatore; Taran, Yuri; Varley, Nicholas; Santiago S., José A.

    2009-04-01

    This study presents baseline data for future geochemical monitoring of the active Tacaná volcano-hydrothermal system (Mexico-Guatemala). Seven groups of thermal springs, related to a NW/SE-oriented fault scarp cutting the summit area (4,100m a.s.l.), discharge at the northwest foot of the volcano (1,500-2,000m a.s.l.); another one on the southern ends of Tacaná (La Calera). The near-neutral (pH from 5.8 to 6.9) thermal ( T from 25.7°C to 63.0°C) HCO3-SO4 waters are thought to have formed by the absorption of a H2S/SO2-CO2-enriched steam into a Cl-rich geothermal aquifer, afterwards mixed by Na/HCO3-enriched meteoric waters originating from the higher elevations of the volcano as stated by the isotopic composition (δD and δ18O) of meteoric and spring waters. Boiling temperature fumaroles (89°C at ~3,600m a.s.l. NW of the summit), formed after the May 1986 phreatic explosion, emit isotopically light vapour (δD and δ18O as low as -128 and -19.9‰, respectively) resulting from steam separation from the summit aquifer. Fumarolic as well as bubbling gases at five springs are CO2-dominated. The δ13CCO2 for all gases show typical magmatic values of -3.6 ± 1.3‰ vs V-PDB. The large range in 3He/4He ratios for bubbling, dissolved and fumarolic gases [from 1.3 to 6.9 atmospheric 3He/4He ratio ( R A)] is ascribed to a different degree of near-surface boiling processes inside a heterogeneous aquifer at the contact between the volcanic edifice and the crystalline basement (4He source). Tacaná volcano offers a unique opportunity to give insight into shallow hydrothermal and deep magmatic processes affecting the CO2/3He ratio of gases: bubbling springs with lower gas/water ratios show higher 3He/4He ratios and consequently lower CO2/3He ratios (e.g. Zarco spring). Typical Central American CO2/3He and 3He/4He ratios are found for the fumarolic Agua Caliente and Zarco gases (3.1 ± 1.6 × 1010 and 6.0 ± 0.9 R A, respectively). The L/ S (5.9 ± 0.5) and ( L + S)/ M

  20. Paleomagnetic, Anisotropy of Magnetic Susceptibility, and 40AR/39AR Data from the Cienega Volcano, Cerros del Rio Volcanic Field, New Mexico

    Science.gov (United States)

    Foucher, M. S.; Petronis, M. S.; Lindline, J.; Van Wyk de Vries, B.

    2012-12-01

    Cinder cone eruptions are typically interpreted to have formed by the ascension of magma through a simple conduit. Recent field work and laboratory studies on different excavated volcanoes around the world suggest that magma transport within cinder cones can involve a complex system of feeder geometries. We studied the Cienega volcano, a cinder cone in the Cerros del Rio volcanic field, northern New Mexico, in order to better understand the complexity and the evolution of volcanic plumbing systems in the development of cinder cone volcanoes. We hypothesized that cinder cone plumbing systems are inherently complex and involve numerous feeder geometries (e.g. dikes, sills) and flow patterns both towards and away from the central vent complex. The Cienega volcano comprises tephra fall deposits as well as several vents, multiple intrusions, and numerous lava flow sequences. We inspected the magmatic plumbing system using different laboratory methods including paleomagnetic, anisotropy of magnetic susceptibility (AMS), rock magnetic and thin section studies. We collected samples across each outcrop of the feeder system. The dikes are olivine porphyritic basalts with major clinopyroxene, calcic plagioclase feldspar, magnetite, and xenocrystic quartz. Most samples display a trachytic texture with plagioclase crystals showing a preferred orientation parallel to the dike margins. The magnetic information is held predominantly by a cubic phase magnetite with a low- to moderate-Ti composition of Single or Pseudo-Single Domain grains. The AMS results show various flow directions. Three of six dikes yielded magma flow directions away from the vent. The other dikes showed both a subvertical flow, which corresponds to the typical movement of magma in a dike originating from a deeper crustal level, and a downward flow direction. We concluded that magma initially flowed upward from the magma chamber until it encountered flow resistance. At this structural level (the current

  1. Chlorine isotope composition of volcanic rocks and gases at Stromboli volcano (Aeolian Islands, Italy): Inferences on magmatic degassing prior to 2014 eruption

    Science.gov (United States)

    Liotta, Marcello; Rizzo, Andrea L.; Barnes, Jaime D.; D'Auria, Luca; Martelli, Mauro; Bobrowski, Nicole; Wittmer, Julian

    2017-04-01

    Among the magmatic volatiles, chlorine (Cl) is degassed at shallow depths offering the opportunity to investigate the behavior of magmatic degassing close to the surface, and the possible occurrence of chemical and isotopic fractionation related to gas/melt partitioning. However, it is still unclear if the isotopic composition of Cl (δ37Cl) can be used as a proxy of magmatic degassing. In this work, we investigate the concentrations of chlorine and sulfur, and the Cl isotope composition of rocks and plume gases collected at Stromboli volcano, Aeolian Islands, Italy. This volcano was chosen because it is characterized by persistent eruptive activity (i.e., Strombolian explosions) and by the presence of magma at very shallow levels in the conduits. Rocks belonging to the different magmatic series erupted throughout the formation of the volcano have δ37Cl values ranging between - 1.0 and + 0.7‰. The isotopic composition seems independent of the Cl concentration of the rocks, but shows a negative correlation with SiO2 content. Plume gases have a greater isotopic compositional variability than the rocks (- 2.2‰ ≤ δ37Cl ≤ + 1.5‰) and the composition seems related to the level of volcanic activity at Stromboli. Gases collected in 2011-2013 during days of ordinary eruptive activity are characterized by δ37Cl values ranging from + 0.3 to + 1.5‰ and S/Cl molar ratios between 1.4 and 2.2, similar to previous S/Cl measurements performed at Stromboli with other techniques. Plume gases collected in July 2014, in days of high-level eruptive activity preceding the onset of the 2014 effusive eruption, have negative δ37Cl values (- 2.2‰ ≤ δ37Cl ≤ - 0.1‰) and S/Cl between 0.9 and 1.2, which are among the lowest S/Cl values measured at this volcano. The amplitude of the volcanic tremor and the variation in the inclination of very long period (VLP) seismic signal polarization clearly indicate that in July 2014 the intensity and frequency of Strombolian

  2. Assessing individual and organizational response to volcanic crisis and unrest at Kīlauea and Mauna Loa volcanoes, Hawai'i

    Science.gov (United States)

    Reeves, Ashleigh; Gregg, Chris; Lindell, Michael; Prater, Carla; Joyner, Timothy; Eggert, Sarah

    2017-04-01

    This study describes response to and preparedness for eruption and unrest at Kīlauea and Mauna Loa volcanoes, respectively. The on-going 1983-present eruption of Kīlauea's East Rift Zone (ERZ) has generated a series of lava flow crises, the latest occurring in 2014 and 2015 when lava from a new vent flowed northeast and into the perimeter of developed areas in the lower Puna District, some 20km distant. It took ca. 2 months for the June 27 lava flow to advance a distance to which scientists reported it might be a concern to people downslope, but this prompted widespread formal and informal responses and culminated in improvements to infrastructure, voluntary evacuations of residents and businesses and closure of schools. Unlike Kīlauea, which has had frequent crises since the mid-20th century, the last eruption of nearby Mauna Loa occurred in 1984 and the last eruption and crisis on its Southwest Rift Zone (SWZ) was in 1950, so residents there are less familiar with eruptions than in Puna. In September 2015, the US Geological Survey, Hawaiian Volcano Observatory upgraded Mauna Loa's Alert Level from Normal to Advisory due to increases in unrest above known background levels. A crisis on Mauna Loa's SWZ would likely be much different than the recent 2014-15 crisis at Kīlauea as steep topography downslope of the SWZ and typical high discharge rates mean lava flows move fast, posing increased risk to areas downslope. Typically, volcanic eruptions have significant economic consequences out of proportion with their magnitudes. Furthermore, uncertainties regarding the physical and organizational communication of risk information amplify these economic losses. One significant impediment to risk communication is limited knowledge about the most effective ways to verbally, numerically and graphically communicate scientific uncertainty. This was a challenge in the recent lava flow crisis on Kīlauea. The public's demand for near-real time information updates, including

  3. Primer registro del ratón de los volcanes (Neotomodon alstoni para el estado de Hidalgo, México First record of the volcano mouse (Neotomodon alstoni from the State of Hidalgo, Mexico

    Directory of Open Access Journals (Sweden)

    Alejandro García-Becerra

    2012-06-01

    Full Text Available El ratón de los volcanes (Neotomodon alstoni se registra por primera vez en el estado de Hidalgo, México. Los ejemplares se recolectaron en diciembre de 2010, en el municipio de Almoloya, aproximadamente a 32.8 km al norte de la localidad documentada más cercana al estado de Tlaxcala, por lo que este nuevo registro se convierte en el más norteño para la distribución conocida del ratón de los volcanes.The volcano mouse (Neotomodon alstoni is firstly recorded in the State of Hidalgo. Specimens were collected in December 2010, at the municipality of Almoloya, approximately 32.8 km to the north from the nearest locality in the state of Tlaxcala. Therefore, this is the northernmost record for the range of the Mexican volcano mouse.

  4. A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity

    Science.gov (United States)

    ALANIS, Paul K. B.; YAMAYA, Yusuke; TAKEUCHI, Akihiro; SASAI, Yoichi; OKADA, Yoshihiro; NAGAO, Toshiyasu

    2013-01-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km × 3 km × 3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano’s activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions. PMID:24126286

  5. Relationship between volcanic ash fallouts and seismic tremor: quantitative assessment of the 2015 eruptive period at Cotopaxi volcano, Ecuador

    Science.gov (United States)

    Bernard, Benjamin; Battaglia, Jean; Proaño, Antonio; Hidalgo, Silvana; Vásconez, Francisco; Hernandez, Stephen; Ruiz, Mario

    2016-11-01

    Understanding the relationships between geophysical signals and volcanic products is critical to improving real-time volcanic hazard assessment. Thanks to high-frequency sampling campaigns of ash fallouts (15 campaigns, 461 samples), the 2015 Cotopaxi eruption is an outstanding candidate for quantitatively comparing the amplitude of seismic tremor with the amount of ash emitted. This eruption emitted a total of 1.2E + 9 kg of ash ( 8.6E + 5 m3) during four distinct phases, with masses ranging from 3.5E + 7 to 7.7E + 8 kg of ash. We compare the ash fallout mass and the corresponding cumulative quadratic median amplitude of the seismic tremor and find excellent correlations when the dataset is divided by eruptive phase. We use scaling factors based on the individual correlations to reconstruct the eruptive process and to extract synthetic Eruption Source Parameters (daily mass of ash, mass eruption rate, and column height) from the seismic records. We hypothesize that the change in scaling factor through time, associated with a decrease in seismic amplitudes compared to ash emissions, is the result of a more efficient fragmentation and transport process. These results open the possibility of feeding numerical models with continuous geophysical data, after adequate calibration, in order to better characterize volcanic hazards during explosive eruptions.

  6. A new Bayesian Event Tree tool to track and quantify volcanic unrest and its application to Kawah Ijen volcano

    Science.gov (United States)

    Tonini, Roberto; Sandri, Laura; Rouwet, Dmitri; Caudron, Corentin; Marzocchi, Warner; Suparjan

    2016-07-01

    Although most of volcanic hazard studies focus on magmatic eruptions, volcanic hazardous events can also occur when no migration of magma can be recognized. Examples are tectonic and hydrothermal unrest that may lead to phreatic eruptions. Recent events (e.g., Ontake eruption on September 2014) have demonstrated that phreatic eruptions are still hard to forecast, despite being potentially very hazardous. For these reasons, it is of paramount importance to identify indicators that define the condition of nonmagmatic unrest, in particular for hydrothermal systems. Often, this type of unrest is driven by movement of fluids, requiring alternative monitoring setups, beyond the classical seismic-geodetic-geochemical architectures. Here we present a new version of the probabilistic BET (Bayesian Event Tree) model, specifically developed to include the forecasting of nonmagmatic unrest and related hazards. The structure of the new event tree differs from the previous schemes by adding a specific branch to detail nonmagmatic unrest outcomes. A further goal of this work consists in providing a user-friendly, open-access, and straightforward tool to handle the probabilistic forecast and visualize the results as possible support during a volcanic crisis. The new event tree and tool are here applied to Kawah Ijen stratovolcano, Indonesia, as exemplificative application. In particular, the tool is set on the basis of monitoring data for the learning period 2000-2010, and is then blindly applied to the test period 2010-2012, during which significant unrest phases occurred.

  7. The Magma feeding system of Somma-Vesuvius (Italy)strato-volcano:new inferences from a review of geochemical and Sr,Nd,Pb and O isotope data. Volcanism in the Campania Plain: Vesuvius, Campi Flegrei and Ignimbrites

    OpenAIRE

    Piochi, M.; De Vivo, B.; Ayuso, R. A.

    2006-01-01

    A large database of major, trace and isotope (Sr, Nd, Pb, O) data exists for rocks produced by the volcanic activity of Somma-Vesuvius volcano. Variation diagrams strongly suggest a major role for evolutionary processes such as fractional crystallization, contamination, crystal trapping and magma mixing, occurring after magma genesis in the mantle. Most mafic magmas are enriched in LILE (K, Rb, Ba), REE (Ce, Sm) and Y, show small Nb–Ta negative anomalies, and have values of Nb/Zr ...

  8. H2O-rich melt inclusions in fayalitic olivine from Hekla volcano: Implications for phase relationships in silicic systems and driving forces of explosive volcanism on Iceland

    Science.gov (United States)

    Portnyagin, Maxim; Hoernle, Kaj; Storm, Sonja; Mironov, Nikita; van den Bogaard, Christel; Botcharnikov, Roman

    2012-12-01

    Silicic Icelandic magmas are widely believed to contain low to moderate H2O content prior to degassing, and that their high explosivity mostly results from the interaction of the magmas with ice or meteoric water. Here we report the compositions of glass inclusions (SiO2=57-72 wt%, K2O=1.3-2.6 wt%) in Fe-rich olivines (Fo2-42) from the largest Holocene eruptions of Hekla volcano (H3 and H4) on Iceland, which preserved quenched melts with very high primary H2O contents (3.3-6.2 wt%). The silicic Hekla melts originate primarily by extensive (˜90%) crystal fractionation of H2O-poor (˜0.6 wt%) basalts and represent an end member in the systematics of terrestrial magmas because they originate at low fO2 (ΔQFM ˜-0.1 to -0.4) and have as high H2O contents as significantly more oxidized island-arc magmas (ΔQFM≥1). This demonstrates that H2O and ΔQFM do not correlate in silicic magmas from different tectonic settings, and that fO2, not H2O content, shows a major difference between silicic ocean-island (e.g., Icelandic) and island-arc magmas. Analysis of available experimental data suggests that high H2O activity and low fO2 expand the field of olivine stability in silicic melts. Low fO2 and low MgO content could also suppress crystallization of amphibole. On the basis of these results we propose that an anhydrous mineral assemblage bearing Fe-rich olivine in evolved volcanic and Skaergaard-type intrusive rocks does not imply low H2O in magmas prior to degassing but, in contrast to the commonly held view, is an indicator of H2O-rich silicic parental magmas crystallized at low fO2. Finally, the high H2O content in magma was a major driving force of the largest explosive eruptions of Hekla volcano and must be at least as important for driving silicic explosive volcanism on Iceland as magma-ice interaction.

  9. Characterizing Volcanic Processes using Near-bottom, High Resolution Magnetic Mapping of the Caldera and Inner Crater of the Kick'em Jenny Submarine Volcano

    Science.gov (United States)

    Ruchala, T. L.; Chen, M.; Tominaga, M.; Carey, S.

    2016-12-01

    Kick'em Jenny (KEJ) is an active submarine volcano located in the Lesser Antilles subduction zone, 7.5 km north of the Caribbean island Grenada. KEJ, known as one of the most explosive volcanoes in Caribbean, erupted 12 times since 1939 with recent eruptions in 2001 and possibly in 2015. Multiple generations of submarine landslides and canyons have been observed in which some of them can be attributed to past eruptions. The structure of KEJ can be characterized as a 1300 m high conical profile with its summit crater located around 180 m in depth. Active hydrothermal venting and dominantly CO2 composition gas seepage take place inside this 250m diameter crater, with the most activity occurring primarily within a small ( 70 x 110 m) depression zone (inner crater). In order to characterize the subsurface structure and decipher the processes of this volcanic system, the Nautilus NA054 expedition in 2014 deployed the underwater Remotely Operated Vehicle (ROV) Hercules to conduct near-bottom geological observations and magnetometry surveys transecting KEJ's caldera. Raw magnetic data was corrected for vehicle induced magnetic noise, then merged with ROV to ship navigation at 1 HZ. To extract crustal magnetic signatures, the reduced magnetic data was further corrected for external variations such as the International Geomagnetic Reference Field and diurnal variations using data from the nearby San Juan Observatory. We produced a preliminary magnetic anomaly map of KEJ's caldera for subsequent inversion and forward modeling to delineate in situ magnetic source distribution in understanding volcanic processes. We integrated the magnetic characterization of the KEJ craters with shipboard multibeam, ROV visual descriptions, and photomosaics. Initial observations show the distribution of short wavelength scale highly magnetized source centered at the north western part of the inner crater. Although locations of gas seeps are ubiquitous over the inner crater area along ROV

  10. Volcanic unrest primed by ice cap melting: A case study of Snæfellsjökull volcano, Western Iceland

    Science.gov (United States)

    Bakker, Richard; Lupi, Matteo; Frehner, Marcel; Berger, Julien; Fuchs, Florian

    2014-05-01

    The most dramatic effect of global warming is the water level rise due to rapid melting of ice sheets. In addition, recent studies suggest that accelerated glacial retreat and associated lithospheric relaxation may enhance upwelling of magmatic fluids through the crust. Here, we investigate whether, also at short geological timescales, shallow magmatic systems may be affected by rapid melting of ice caps. As a case study, we chose the Snæfellsjökull volcanic system in western Iceland, whose ice cap is rapidly melting with 1.25 m(w.e.)/year. To investigate the role of deglaciation in promoting volcanic unrest we use a cross-disciplinary approach integrating geophysical field data, laboratory rheological rock tests, and numerical finite-element analysis. Initial results from seismic data acquisition and interpretation in 2011 show seismic activity (occasionally in swarm sequences) at around a depth range of 8-13 km, indicating the presence of a magmatic reservoir in the crust. In addition, a temporary seismic network of 21 broad-band stations has been deployed in spring 2013 and continuously collected data for several months, which will help better constrain the subsurface geometry. During summer 2013 we collected samples of Tertiary basaltic bedrock from the flanks of Snæfellsjökull, which we assume to be representative for the subsurface volcanic system. Cores drilled from these samples were tri-axially deformed in a Paterson-type apparatus at a constant strain rate of 10-5 s-1, a confining pressure of 50 MPa (i.e. ~2 km depth), and a temperature ranging from 200 °C to 1000 °C (i.e. various proximities to magma chamber). From the obtained stress-strain curves the static Young's modulus is calculated to be around 35 (±2) GPa, which is not significantly influenced by increasing temperatures up to 800 °C. Beyond the elastic domain, cataclastic shear bands develop, accommodating up to 7% strain before brittle failure. The subsurface geometrical constraints from

  11. Depositional and Immersion-Mode Ice Nucleation of Fine-Grained Volcanic Ash Samples

    Science.gov (United States)

    Cloer, S.; Woods, T.; Genareau, K. D.

    2016-12-01

    Volcanic lightning is a common phenomenon during explosive eruptions; occurring as vent discharges, near-vent discharges, and plume lightning. Plume lightning is most similar to thunderstorm lightning, where volcanic ash may act as ice nuclei. Volcanic ash samples derived from eight volcanoes: Augustine, Crater Peak, Katmai, Okmok, Redoubt (Alaska, U.S.A.), Lathrop Well (Nevada, U.S.A.), Taupo (New Zealand), and Valles Caldera (New Mexico, U.S.A.); were used to determine what roles ash mineralogy, particularly Fe-oxide-bearing minerals and silica-enriched minerals, grain shape, and grain size have in the nucleation of ice, which can generate plume lightning. Depositional and immersion-mode ice nucleation experiments were performed using a Nicolet Almega XR Dispersive Raman spectrometer, following the methods of Schill et al. (2015), where samples were shaken for 24 h prior to experiments in ultra-pure water, then nebulized to super micron droplets. Depositional nucleation experiments were conducted from 225-235 K, and immersion-mode nucleation experiments were conducted from 233-278 K. A JEOL JSM 6010 Plus/LA scanning electron microscope (SEM), along with Image-J freeware, was used to quantify the number density of Fe-oxide mineral phases in backscattered electron images, with an x-ray diffractometer (XRD) used to determine bulk mineral abundance and an x-ray fluorescence (XRF) spectrometer to determine bulk ash composition. Based on previous studies, we hypothesize that all ash samples will efficiently form depositional ice nuclei; however, certain mineral phases will dictate the efficiency of immersion-mode ice nucleation including K or Na / Ca feldspars, which have been shown to be efficient nuclei, and Fe-oxide-bearing minerals. These results will shed new light on volcanic cloud dynamics and add new parameters for atmospheric models, which currently only address effects of mineral dust as ice nuclei and overlook the potential role of volcanic ash.

  12. Self-potential changes associated with volcanic activity. Short-term signals associated with March 9, 1998 eruption on La Fournaise volcano (Reunion Island)

    Energy Technology Data Exchange (ETDEWEB)

    Zlotniki, J. [UMR6530, Clermont-Ferrand (France); Institut de Physique du Globe de Paris, Laboratoire de Geomagnetisme, Paris (France); Le Mouel, J. L. [Institut de Physique du Globe de Paris, Laboratoire de Geomagnetisme, Paris (France); Sasai, Y. [Tokyo Univ., Tokyo (Italy). Earthquake Research Institute; Yvetot, P.; Ardisson, M. H. [UMR6524, Laboratoire de Geophysique d' Orleans, Orleans (France)

    2001-04-01

    After six years of quietness La Fournaise volcano entered into activity on March 9, 1998. Fissures opened gradually downwards on the northern flank of the cone. Two cones, Kapor and Krafft built, from which lava poured until September 1998. Several other vents opened during this eruption. Mappings, surveys, and continuous recordings of the Self-Potential have been performed on the volcano for twenty years. SP mappings disclose the variability of large scale SP anomalies due to the modification of the hydrothermal system over some ten years. Most of the eruptions take place along a Main Fracture Zone (MFZ), in which ground water flows prevail. SP measurements have also regularly been made on the northern flank of the cone, on a west-east profile crossing the MFZ. Between 1981 and 1992 an enlargement and a shift of the MFZ to the east are evidenced. In particular, the eastern fissural axis trending N35{sup 0}E could be related to the possible collapse of the east flank of the volcano. After a decrease between 1992 and 1997, the SP anomaly was enhanced again by the 1998 eruption. Short scale, about 250 m wide, 750 mV amplitude anomalies were superimposed on a large scale one, 2500 m wide, and about 250 mV in amplitude. For several years, continuous stations have been measuring the electric field along two directions, with a 20 s sampling, in order to record the genesis of SP signals associated with the volcanic activity. Oscillations belonging to the ULF band were evidenced several days before the 1988 eruption, some of them at 9 km from the summit. Their amplitude reached several tens mV/km. These oscillations sometimes present a phase lag from summit. Their amplitude reached several tens mV/km. These oscillations sometimes present a phase lag from one station to another; they progressively shift towards the location of the future effusive vents. The polarisation of the oscillations is similar to the polarisation of longer SP variations (1 h period or more) and are

  13. Self-potential chenges associated with volcanic activity: Short-term signals associated with March 9, 1998 eruption on La Fournaise volcano (Reunion Island

    Directory of Open Access Journals (Sweden)

    P. Yvetot

    2001-06-01

    Full Text Available After six years of quietness La Fournaise volcano entered into activity on March 9, 1998. Fissures opened gradually downwards on the northern flank of the cone. Two cones, Kapor and Krafft built, from which lava poured until September 1998. Several other vents opened during this eruption. Mappings, surveys, and continuous recordings of the Self-Potential have been performed on the volcano for twenty years. SP mappings disclose the variability of large scale SP anomalies due to the modification of the hydrothermal system over some ten years. Most of the eruptions take place along a Main Fracture Zone (MFZ in which ground water flows prevail. SP measurements have also regularly been made on the northern flank of the cone, on a west-east profile crossing the MFZ. Between 1981 and 1992 an enlargement and a shift of the MFZ to the east are evidenced. In particular, the eastern fissural axis trending N35°E could be related to the possible collapse of the east flank of the volcano. After a decrease between 1992 and 1997, the SP anomaly was enhanced again by the 1998 eruption. Short scale, about 250 m wide, 750 mV amplitude anomalies were superimposed on a large scale one, 2500 m wide, and about 250 mV in amplitude. For several years, continuous stations have been measuring the electric field along two directions, with a 20 s sampling, in order to record the genesis of SP signals associated with the volcanic activity. Oscillations belonging to the ULF band were evidenced several days before the 1988 eruption, some of them at 9 km from the summit. Their amplitude reached several tens mV/km. These oscillations sometimes present a phase lag from one station to another; they progressively shift towards the location of the future effusive vents. The polarisation of the oscillations is similar to the polarisation of longer SP variations (1 h period or more and are correlated with the structural anisotropy. Finally, during the last hours preceding the

  14. Double, double, (but mostly) toil, and trouble: A multidisciplinary approach to quantify the permeability of an active volcanic hydrothermal system (Whakaari volcano, New Zealand)

    Science.gov (United States)

    Heap, Michael; Kennedy, Ben; Farquharson, Jamie; Ashworth, James; Mayer, Klaus; Letham-Brake, Mark; Reuschlé, Thierry; Gilg, Albert; Scheu, Betty; Lavallée, Yan; Siratovich, Paul; Cole, Jim; Jolly, Art; Dingwell, Donald

    2016-04-01

    Our multidisciplinary approach, which combines field techniques and traditional laboratory methods, aims to better understand the permeability of an active volcanic hydrothermal system, a vital prerequisite for understanding and modelling the behaviour of hydrothermal systems worldwide. Whakaari volcano (an active stratovolcano located 48 km off New Zealand's North Island) hosts an open, highly reactive hydrothermal system (hot springs and mud pools, fumaroles, acid streams and lakes) and represents an ideal natural laboratory to undertake such a study. We first gained an appreciation of the different lithologies at Whakaari and (where possible) their lateral and vertical extent through reconnaissance by land, sea, and air. Due to the variable nature of these altered lithologies (mainly lavas and tuffs), we measured porosity-permeability for in excess of a hundred rock hand samples using field techniques. We also measured the permeability of recent, unconsolidated deposits using a field soil permeameter. Our field measurements were then groundtruthed on a subset of these samples (~40-50) using traditional laboratory techniques: helium pycnometry and measurements of permeability using a benchtop permeameter, including measurements under increasing confining pressure (i.e., depth). In all, our measurements highlight that the porosity of the materials at Whakaari can vary from ~0.01 to ~0.6, and permeability can vary by eight orders of magnitude. However, our data show no discernable trend between porosity and permeability. A combination of macroscopic and microscopic observations, chemistry (XRF), mineralogy (XRD), and mercury porosimetry highlight that the absence of a robust porosity-permeability relationship is the product of an insane variability in alteration and microstructure (pore size, particle size, pore connectivity, presence/absence of microcracks, layering, amongst others). While our systematic study offers the most complete porosity-permeability dataset

  15. 五大连池老黑山火山弹和喷发柱动力学模拟%Simulation on the Dynamic Process of Volcanic Bombs and Plumes of Laoheishan Volcano in Wudalianchi Area

    Institute of Scientific and Technical Information of China (English)

    李永生; 刘永顺; 张招崇; 聂保锋; 张东阳

    2012-01-01

    The volcanic eruption is a complex fluid dynamic process of gas, liquid and solid mixtures. A correct understanding of this process is the key factor to study the volcanic eruption. Eject and Plumeria softwares can be good simulations for dynamic processes of volcanic bombs and plumes during real volcanic eruption. On the basis of detailed investigation of volcanic bombs, volcanic debris and the published data of Laoheishan volcano in Wudalianchi area, this study evaluated dynamic processes of Laoheishan volcanic bombs and plumes using Eject and Plumeria softwares. The results show that the bombs ejected from Laoheishan volcano can reach a maximum height of 530 m and a maximum horizontal distance of 1,000 m when ejection angle is 45°; the maximum height of its volcanic plume is 4. 7 km, and the plume head radius is 2. 3 km. Through the discussion of the eruption scale and the ratio of volcanic ashes, it can be concluded that Laoheishan volcano is a small mafic eruption, and its effect on the environment is small.%火山喷发是一个气体、液体和固体混合物的复杂的流体动力学过程.正确理解这个过程是研究火山喷发的关键因素.Eject和Plumeria软件可以很好地模拟现实火山喷发过程中火山弹和喷发柱的动力学过程.在详细调查五大连池老黑山地区火山弹、火山碎屑物和整理已有数据的基础上,运用Eject和Plumeria软件对老黑山火山的火山弹和喷发柱进行了动力学模拟.结果表明:老黑山火山喷发的火山弹喷射最大高度为530 m,喷射角度45.时喷射水平距离最远为1000m,喷发柱最大高度为4.7 km,喷发柱半径为2.3 km.通过对其喷发规模和火山灰构成比例的探讨,认为老黑山火山喷发属于镁铁质火山小型喷发,对环境的影响范围有限.

  16. Economic impact of explosive volcanic eruptions: A simulation-based assessment model applied to Campania region volcanoes

    Science.gov (United States)

    Zuccaro, Giulio; Leone, Mattia Federico; Del Cogliano, Davide; Sgroi, Angelo

    2013-10-01

    PLINIVS Study Centre of University of Naples Federico II has developed a methodology that aims to estimate, in probabilistic terms, the direct and the indirect economic impacts of a Sub-Plinian I or Strombolian type eruption of Vesuvius. The economic model has been implemented as a complementary tool of the Volcanic Impact Simulation Model, a tool developed at PLINIVS Center available to the Italian Civil Protection Department (DPC) decision makers to quantify the potential losses consequent to a possible eruption of Vesuvius or Campi Flegrei. Along the expected time history of the eruptive event all the possible "direct costs" and the "factors" (indirect costs) impacting the economic growth in the event area have been identified. Each cost factor is built up through a specific algorithm that is fed by various providers, in order to run software that will estimate the global amount of economic damage from a volcanic event. The model does not include the economic evaluation of intangibles (e.g. human casualties), while the evaluation of damage to the local cultural heritage (historical buildings, archeological sites, monuments, etc.), is linked to the economic impact on tourism, estimated into indirect costs. The architecture of the model is based on a simulation logic, which allows an evaluation of different economic impact scenarios through input changes, allowing the model to be used as a tool to support the decision making process.

  17. Volcano-tectonic structures, gravity and helium in geothermal areas of Tuscany and Latium (Vulsini volcanic district), Italy

    Science.gov (United States)

    Di, Filippo M.; Lombardi, S.; Nappi, G.; Reimer, G.M.; Renzulli, A.; Toro, B.

    1999-01-01

    Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.

  18. An overview of a landslide susceptibility methodology for identification of unstable slopes in volcanic terrains. A case-control study in Pico de Orizaba volcano, México

    Science.gov (United States)

    Legorreta Paulin, G.; Lugo Hubp, J.

    2010-12-01

    Landslides have been studied using several approaches - inventory, heuristic, statistical, and deterministic. Each approach has advantages and limitations for assigning landslide potential. This poster presents a comprehensive qualitative and quantitative approach to characterize areas that are prone to slope instability in volcanic terrains. The Río Chiquito-Barranca del Muerto watershed is selected as the case-control study area. The watershed is located on the southwestern flank of the highest mountain in Mexico, Pico de Orizaba volcano. The study area has a combination of several contributing factors to landsliding such as high rain fall during the wet season, rock types, high degree of weathering, and steep slopes. With the goal of identifying areas within the watershed that have a low, moderate, or high risk of landslides, a representative sample of mass-wasting features were inventoried from aerial photography and field investigations. This analysis divided the watershed into mass wasting terrain units to analyze its behavior. The data developed during this project consist of a multi-temporal landslide inventory map, terrain unit descriptions, and a report detailing the landslide hazard findings.

  19. Chlorine isotope and Cl-Br fractionation in fluids of Poás volcano (Costa Rica): Insight into an active volcanic-hydrothermal system

    Science.gov (United States)

    Rodríguez, Alejandro; Eggenkamp, H. G. M.; Martínez-Cruz, María; van Bergen, Manfred J.

    2016-10-01

    Halogen-rich volcanic fluids issued at the surface carry information on properties and processes operating in shallow hydrothermal systems. This paper reports a long-term record of Cl-Br concentrations and δ37Cl signatures of lake water and fumaroles from the active crater of Poás volcano (Costa Rica), where surface expressions of magmatic-hydrothermal activity have shown substantial periodic changes over the last decades. Both the hyperacid water of its crater lake (Laguna Caliente) and subaerial fumaroles show significant temporal variability in Cl-Br concentrations, Br/Cl ratios and δ37Cl, reflecting variations in the mode and magnitude of volatile transfer. The δ37Cl signatures of the lake, covering the period 1985-2012, show fluctuations between + 0.02 ± 0.06‰ and + 1.15 ± 0.09‰. Condensate samples from adjacent fumaroles on the southern shore, collected during the interval (2010-2012) with strong changes in gas temperature (107-763°C), display a much larger range from - 0.43 ± 0.09‰ to + 14.09 ± 0.08‰. Most of the variations in Cl isotope, Br/Cl and concentration signals can be attributed to interaction between magma-derived gas and liquid water in the volcanic-hydrothermal system below the crater. The δ37Cl were lowest and closest to magmatic values in (1) fumarolic gas that experienced little or no interaction with subsurface water and followed a relatively dry pathway, and (2) water that captured the bulk of magmatic halogen output so that no phase separation could induce fractionation. In contrast, elevated δ37Cl can be explained by partial scavenging and fractionation during subsurface gas-liquid interaction. Hence, strong Cl isotope fractionation leading to very high δ37Cl in Poás' fumaroles indicates that they followed a wet pathway. Highest δ37Cl values in the lake water were found mostly in periods when it received a significant input from subaqueous fumaroles or when high temperatures and low pH caused HCl evaporation. It is

  20. Volcanic Rocks and Features

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanoes have contributed significantly to the formation of the surface of our planet. Volcanism produced the crust we live on and most of the air we breathe. The...

  1. δ18O and δD variations in some volcanic lakes on the Cameroon Volcanic Line (West-Africa: generating isotopic baseline data for volcano monitoring and surveillance in Cameroon

    Directory of Open Access Journals (Sweden)

    . Issa

    2014-06-01

    Full Text Available Based on geo-anthropological and geochemical studies, catastrophes similar to the unprecedented gas explosions in the mid-1980s from the Cameroonian killer lakes Nyos and Monoun, might occur in any of the 37 other lakes located along the Cameroon Volcanic Line (CVL. Because people could suffer loss and desolation from predictable catastrophes in the future, monitoring/surveillance policies must be established. Due to their location, crater lakes integrate the geochemical processes that develop in the Earth’s crust due to magmatic activities. Therefore, monitoring the surface manifestations of those deep seated and/or hydrothermal processes might reveal increases/decreases in magmatic activities. The anomalous changes in a volcanic lake induced by mixing with exogenous fluids that have a specific δ18O and δD compositional fingerprint (magmatic, metamorphic, etc. could be utilized to predict volcanic hazards. If the steady state of a lake environment and the external and intrinsic parameters that control its hydrodynamics are clearly identified and reasonably understood, the anomalous evolutionary processes that compromise its stability can be identified. This study attempts to collect the δ18O and δD data from 17 Cameroonian lakes to help establish a volcano-related monitoring/surveillance network. This work identifies the processes that control the isotopic composition of the lakes and assesses the intra-/inter- and spatial δ18O/δD variations. Almost all of the lakes contain meteoric water. These lakes are mostly isotopically stratified; epilimnia is generally more positive than the hypolimnia. However, although the rainfall is gradually depleted in heavy isotopes when moving from the South to the North due to the latitude effect, the lakes become more enriched (0.6‰/100 km due to evaporation. The evaluated impact of several parameters on the isotopic variation suggests that the hydrological setting may play an important, albeit not

  2. Monogenetic volcanoes fed by interconnected dikes and sills in the Hopi Buttes volcanic field, Navajo Nation, USA

    Science.gov (United States)

    Muirhead, James D.; Van Eaton, Alexa R.; Re, Giuseppe; White, James D. L.; Ort, Michael H.

    2016-01-01

    Although monogenetic volcanic fields pose hazards to major cities worldwide, their shallow magma feeders (volcanic field, Arizona, to shed light on the nature of its magma feeder system. Shallow exposures reveal a transition zone between intrusion and eruption within 350 m of the syn-eruptive surface. Using a combination of field- and satellite-based observations, we have identified three types of shallow magma systems: (1) dike-dominated, (2) sill-dominated, and (3) interconnected dike-sill networks. Analysis of vent alignments using the pyroclastic massifs and other eruptive centers (e.g., maar-diatremes) shows a NW-SE trend, parallel to that of dikes in the region. We therefore infer that dikes fed many of the eruptions. Dikes are also observed in places transforming to transgressive (ramping) sills. Estimates of the observable volume of dikes (maximum volume of 1.90 × 106 m3) and sills (minimum volume of 8.47 × 105 m3) in this study reveal that sills at Hopi Buttes make up at least 30 % of the shallow intruded volume (∼2.75 × 106 m3 total) within 350 m of the paeosurface. We have also identified saucer-shaped sills, which are not traditionally associated with monogenetic volcanic fields. Our study demonstrates that shallow feeders in monogenetic fields can form geometrically complex networks, particularly those intruding poorly consolidated sedimentary rocks. We conclude that the Hopi Buttes eruptions were primarily fed by NW-SE-striking dikes. However, saucer-shaped sills also played an important role in modulating eruptions by transporting magma toward and away from eruptive conduits. Sill development could have been accompanied by surface uplifts on the order of decimeters. We infer that the characteristic feeder systems described here for the Hopi Buttes may underlie monogenetic fields elsewhere, particularly where magma intersects shallow, and often weak, sedimentary rocks. Results from this study support growing evidence of the

  3. Volcano-tectonic structures, gravity and helium in geothermal areas of Tuscany and Latium (Vulsini volcanic district), Italy

    Energy Technology Data Exchange (ETDEWEB)

    Di Filippo, Michele; Lombardi, Salvatore; Toro, Beniamino [Universita di Roma ' La Sapienza' , Dip. di Scienze della Terra, Roma (Italy); Nappi, Giovanni; Renzulli, Alberto [Universita di Urbino, Ist. di Mineralogia e Petrologia, Urbino (Italy); Reimer, G. Michael [U.S. Geological Survey, Federal Center, Denver, CO (United States)

    1999-06-01

    Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of 100degC/km, and by widespread hydrothermal mineralisation, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth. (Author)

  4. Structure and kinematics of the Taupo Rift, New Zealand

    Science.gov (United States)

    Seebeck, Hannu; Nicol, Andrew; Villamor, Pilar; Ristau, John; Pettinga, Jarg

    2014-06-01

    The structure and kinematics of the continental intra-arc Taupo Rift have been constrained by fault-trace mapping, a large catalogue of focal mechanisms (N = 202) and fault slip striations. The mean extension direction of ~137° is approximately orthogonal to the regional trend of the rift and arc front (α = 84° and 79°, respectively) and to the strike of the underlying subducting Pacific Plate. Bending and rollback of the subduction hinge strongly influence the location, orientation, and extension direction of intra-arc rifting in the North Island. In detail, orthogonal rifting (α = 85-90°) transitions northward to oblique rifting (α = 69-71°) across a paleovertical-axis rotation boundary where rift faults, extension directions, and basement fabric rotate by ~20-25°. Toward the south, extension is orthogonal to normal faults which are parallel to, and reactivate, steeply dipping basement fabric. Basement reactivation facilitates strain partitioning with a portion of margin-parallel motion in the overriding plate mainly accommodated east of the rift by strike-slip faults in the North Island Fault System (NIFS). Toward the north where the rift and NIFS intersect, ~4 mm/yr strike slip is transferred into the rift with net oblique extension accommodating a component of margin-parallel motion. The trend and kinematics of the Taupo Rift are comparable to late Miocene-Pliocene intra-arc rifting in the Taranaki Basin, indicating that the northeast strike of the subducting plate and the southeast extension direction have been uniform since at least 4 Ma.

  5. Volcanic hazards and aviation safety

    Science.gov (United States)

    Casadevall, Thomas J.; Thompson, Theodore B.; Ewert, John W.; ,

    1996-01-01

    An aeronautical chart was developed to determine the relative proximity of volcanoes or ash clouds to the airports and flight corridors that may be affected by volcanic debris. The map aims to inform and increase awareness about the close spatial relationship between volcanoes and aviation operations. It shows the locations of the active volcanoes together with selected aeronautical navigation aids and great-circle routes. The map mitigates the threat that volcanic hazards pose to aircraft and improves aviation safety.

  6. The role of viscous magma mush spreading in volcanic flank motion at Kīlauea Volcano, Hawai‘i

    Science.gov (United States)

    Plattner, C.; Amelung, F.; Baker, S.; Govers, R.; Poland, M.

    2013-01-01

    Multiple mechanisms have been suggested to explain seaward motion of the south flank of Kīlauea Volcano, Hawai‘i. The consistency of flank motion during both waxing and waning magmatic activity at Kīlauea suggests that a continuously acting force, like gravity body force, plays a substantial role. Using finite element models, we test whether gravity is the principal driver of long-term motion of Kīlauea's flank. We compare our model results to geodetic data from Global Positioning System and interferometric synthetic aperture radar during a time period with few magmatic and tectonic events (2000-2003), when deformation of Kīlauea was dominated by summit subsidence and seaward motion of the south flank. We find that gravity-only models can reproduce the horizontal surface velocities if we incorporate a regional décollement fault and a deep, low-viscosity magma mush zone. To obtain quasi steady state horizontal surface velocities that explain the long-term seaward motion of the flank, we find that an additional weak zone is needed, which is an extensional rift zone above the magma mush. The spreading rate in our model is mainly controlled by the magma mush viscosity, while its density plays a less significant role. We find that a viscosity of 2.5 × 1017–2.5 × 1019 Pa s for the magma mush provides an acceptable fit to the observed horizontal surface deformation. Using high magma mush viscosities, such as 2.5 × 1019 Pa s, the deformation rates remain more steady state over longer time scales. These models explain a significant amount of the observed subsidence at Kīlauea's summit. Some of the remaining subsidence is probably a result of magma withdrawal from subsurface reservoirs

  7. The role of viscous magma mush spreading in volcanic flank motion at Kīlauea Volcano, Hawai`i

    Science.gov (United States)

    Plattner, C.; Amelung, F.; Baker, S.; Govers, R.; Poland, M.

    2013-05-01

    Multiple mechanisms have been suggested to explain seaward motion of the south flank of Kīlauea Volcano, Hawai`i. The consistency of flank motion during both waxing and waning magmatic activity at Kīlauea suggests that a continuously acting force, like gravity body force, plays a substantial role. Using finite element models, we test whether gravity is the principal driver of long-term motion of Kīlauea's flank. We compare our model results to geodetic data from Global Positioning System and interferometric synthetic aperture radar during a time period with few magmatic and tectonic events (2000-2003), when deformation of Kīlauea was dominated by summit subsidence and seaward motion of the south flank. We find that gravity-only models can reproduce the horizontal surface velocities if we incorporate a regional décollement fault and a deep, low-viscosity magma mush zone. To obtain quasi steady state horizontal surface velocities that explain the long-term seaward motion of the flank, we find that an additional weak zone is needed, which is an extensional rift zone above the magma mush. The spreading rate in our model is mainly controlled by the magma mush viscosity, while its density plays a less significant role. We find that a viscosity of 2.5 × 1017-2.5 × 1019 Pa s for the magma mush provides an acceptable fit to the observed horizontal surface deformation. Using high magma mush viscosities, such as 2.5 × 1019 Pa s, the deformation rates remain more steady state over longer time scales. These models explain a significant amount of the observed subsidence at Kīlauea's summit. Some of the remaining subsidence is probably a result of magma withdrawal from subsurface reservoirs.

  8. The role of viscous magma mush spreading in volcanic flank motion at Kilauea Volcano, Hawai'i

    Science.gov (United States)

    Plattner, Christina; Amelung, Falk; Baker, Scott; Govers, Rob; Poland, Mike

    2014-05-01

    Multiple mechanisms have been suggested to explain seaward motion of the south flank of Kīlauea Volcano, Hawai'i. The consistency of flank motion during both waxing and waning magmatic activity at Kīlauea suggests that a continuously acting force, like gravity body force, plays a substantial role. Using finite element models, we test whether gravity is the principal driver of long-term motion of Kīlauea's flank. We compare our model results to geodetic data from Global Positioning System and interferometric synthetic aperture radar during a time period with few magmatic and tectonic events (2000-2003), when deformation of Kīlauea was dominated by summit subsidence and seaward motion of the south flank. We find that gravity-only models can reproduce the horizontal surface velocities if we incorporate a regional décollement fault and a deep, low-viscosity magma mush zone. To obtain quasi steady state horizontal surface velocities that explain the long-term seaward motion of the flank, we find that an additional weak zone is needed, which is an extensional rift zone above the magma mush. The spreading rate in our model is mainly controlled by the magma mush viscosity, while its density plays a less significant role.We find that a viscosity of 2.5 x 10^17 - 2.5 x 10^19 Pa s for the magma mush provides an acceptable fit to the observed horizontal surface deformation. Using high magma mush viscosities, such as 2.5 x 10^19 Pa s, the deformation rates remain more steady state over longer time scales. These models explain a significant amount of the observed subsidence at Kīlauea's summit. Some of the remaining subsidence is probably a result of magma withdrawal from subsurface reservoirs.

  9. Contribution of volcanic ashes to the regional geochemical balance: the 2008 eruption of Chaitén volcano, Southern Chile.

    Science.gov (United States)

    Ruggieri, F; Fernandez-Turiel, J L; Saavedra, J; Gimeno, D; Polanco, E; Amigo, A; Galindo, G; Caselli, A

    2012-05-15

    The environmental geochemical behaviour of the rhyolitic ashes from the 2008 eruption of Chaitén volcano, Southern Chile, has been studied. After the bulk characterisation, the potential contribution to the regional geochemical fluxes was examined using: i) single batch leaching tests to provide a rapid screening of the implied major and trace elements; and ii) column experiments to evaluate the temporal mobility of leached elements. The environmental concerns of these ashes are related to the fine grained component present in each sample (independent of distance from the source), in particular the presence of cristobalite, and the geochemical hazards posed by ash-water interaction. Leaching experiments show the fast dissolution of surface salts and aerosols, which dominate over glass dissolution during the first steps of the ash-water interaction. Chaitén ashes could transfer to the environment more than 1×10(10)g or 10,000 metric tonnes (mt) of Cl, S, Ca, Na, Si, and K; between 1000 and 10,000 mt of F, Mg, and Al; between 100 and 1000 mt of As, Pb, P, Fe, Sr, Zn, Mn, and Br; between 10 and 100 mt of Ba, Li, Ti, Ni, Nb, Cu, Rb, Zr, V, Mo, Co, and Sc; and less than 10 mt of Cr, Sb, Ce, Ga, Cs, and Y. These results show the fertilising potential of the ashes (e.g., providing Ca and Fe) but also the input of potentially toxic trace elements (e.g., F and As) in the regional geochemical mass balance. The Chaitén results evidence lower potentials for poisoning and fertilising than low silica ashes due to the lower contents released of practically all elements.

  10. Geothermal disruption of ice at Mount Spurr Volcano, 2004 - 2006: An unusual manifestation of volcanic unrest in Alaska

    Science.gov (United States)

    Coombs, Michelle L.; Neal, Christina A.; Wessels, Rick L.; McGimsey, Robert G.

    2006-01-01

    Mount Spurr, a 3,374-m-high stratovolcano in the Cook Inlet region of Alaska, showed signs of volcanic unrest beginning in 2004 and lasting through 2006. These signs included increases in heat flow, seismicity, and gas flux, which we interpret as the results of a magmatic intrusion in mid-2004. In response, debris-laden meltwater beneath the glacier in Mount Spurr's geothermally active summit basin accumulated as the overlying snow and ice melted. As heat output increased, the icecap subsided into a growing cavity over a meltwater lake, similar to that observed during subglacial volcanic activity in Iceland. An ice plug collapsed into the lake sometime between June 20 and July 8, 2004, forming an ice cauldron that continued to grow in diameter during 2004 and 2005. A freefall of ice and snow into the lake likely caused a mixture of water and debris to be displaced rapidly upward and outward along preexisting englacial and, possibly, subglacial pathways leading away and downslope from the summit basin. Where these pathways intersected crevasses or other weak points in the sloping icefield, the mixture debouched onto the surface, producing dark, fluid debris flows. In summer 2004, the occurrence of two sets of debris flows separated in time by as long as a week suggests two pulses of summit ice collapse, each producing a surge of water and debris from the lake. A single debris flow was also emplaced on May 2, 2005. This event, which was captured by a Web camera, occurred simultaneously with a lake-level drop of ~15 m. To the east of the ice cauldron, a spillway that fed the debris flows has apparently maintained a relatively constant lake level for months at a time. Aerial photographs show that the spillway is in the direction of a breach in the summit crater. Melting of snow and ice at the summit has continued through 2006, with a total meltwater volume of ~5.4 million m3 as of March 2006.

  11. Magmatic controls on eruption dynamics of the 1950 yr B.P. eruption of San Antonio Volcano, Tacaná Volcanic Complex, Mexico-Guatemala

    Science.gov (United States)

    Mora, Juan Carlos; Gardner, James Edward; Macías, José Luis; Meriggi, Lorenzo; Santo, Alba Patrizia

    2013-07-01

    San Antonio Volcano, in the Tacaná Volcanic Complex, erupted ~ 1950 yr. B.P., with a Pelean type eruption that produced andesitic pyroclastic surges and block-and-ash flows destroying part of the volcano summit and producing a horse-shoe shaped crater open to the SW. Between 1950 and 800 yr B.P. the eruption continued with effusive andesites followed by a dacite lava flow and a summit dome, all from a single magma batch. All products consist of phenocrysts and microphenocrysts of zoned plagioclase, amphibole, pyroxene, magnetite ± ilmenite, set in partially crystallized groundmass of glass and microlites of the same mineral phases, except for the lack of amphibole. Included in the andesitic blocks of the block-and-ash flow deposit are basaltic andesite enclaves with elongated and ellipsoidal forms and chilled margins. The enclaves have intersertal textures with brown glass between microphenocrysts of plagioclase, hornblende, pyroxene, and olivine, and minor proportions of phenocrysts of plagioclase, hornblende, and pyroxene. A compositional range obtained of blocks and enclaves resulted from mixing between andesite (866 °C ± 22) and basaltic andesite (enclaves, 932 °C ± 22), which may have triggered the explosive Pelean eruption. Vestiges of that mixing are preserved as complex compositional zones in plagioclase and clinopyroxene-rich reaction rims in amphibole in the andesite. Whole-rock chemistry, geothermometry, experimental petrology and modeling results suggest that after the mixing event the eruption tapped hybrid andesitic magma (≤ 900 °C) and ended with effusive dacitic magma (~ 825 °C), all of which were stored at ~ 200 MPa water pressure. A complex open-system evolution that involved crustal end-members best explains the generation of effusive dacite from the hybrid andesite. Amphibole in the dacite is rimmed by reaction products of plagioclase, orthopyroxene, and Fe-Ti oxides produced by decompression during ascent. Amphibole in the andesite

  12. Transition from alkaline to calc-alkaline volcanism during evolution of the Paleoproterozoic Francevillian basin of eastern Gabon (Western Central Africa)

    Science.gov (United States)

    Thiéblemont, Denis; Bouton, Pascal; Préat, Alain; Goujou, Jean-Christian; Tegyey, Monique; Weber, Francis; Ebang Obiang, Michel; Joron, Jean Louis; Treuil, Michel

    2014-11-01

    We report new geochemical data for the volcanic and subvolcanic rocks associated with the evolution of the Francevillian basin of eastern Gabon during Paleoproterozoic times (c. 2.1-2 Ga). Filling of this basin has proceeded through four main sedimentary or volcano-sedimentary episodes, namely FA, FB, FC and FD. Volcanism started during the FB episode being present only in the northern part of the basin (Okondja sub-basin). This volcanism is ultramafic to trachytic in composition and displays a rather constant alkaline geochemical signature. This signature is typical of a within-plate environment, consistent with the rift-setting generally postulated for the Francevillian basin during the FB period. Following FB, the FC unit is 10-20 m-thick silicic horizon (jasper) attesting for a massive input of silica in the basin. Following FC, the FD unit is a c. 200-400 m-thick volcano-sedimentary sequence including felsic tuffs and epiclastic rocks. The geochemical signatures of these rocks are totally distinct from those of the FB alkaline lavas. High Th/Ta and La/Ta ratios attest for a calc-alkaline signature and slight fractionation between heavy rare-earth suggests melting at a rather low pressure. Such characteristics are comparable to those of felsic lavas associated with the Taupo zone of New Zealand, a modern ensialic back-arc basin. Following FD, the FE detrital unit is defined only in the Okondja region, probably associated with a late-stage collapse of the northern part of the basin. It is suggested that the alkaline to calc-alkaline volcanic transition reflects the evolution of the Francevillian basin from a diverging to a converging setting, in response to the onset of converging movements in the Eburnean Belt of Central Africa.

  13. Volcano crisis response at Yellowstone volcanic complex - after-action report for exercise held at Salt Lake City, Utah, November 15, 2011

    Science.gov (United States)

    Pierson, Thomas C.; Driedger, Carolyn L.; Tilling, Robert I.

    2013-01-01

    A functional tabletop exercise was run on November 14-15, 2011 in Salt Lake City, Utah, to test crisis response capabilities, communication protocols, and decision-making by the staff of the multi-agency Yellowstone Volcano Observatory (YVO) as they reacted to a hypothetical exercise scenario of accelerating volcanic unrest at the Yellowstone caldera. The exercise simulated a rapid build-up of seismic activity, ground deformation, and hot-spring water-chemistry and temperature anomalies that culminated in a small- to moderate-size phreatomagmatic eruption within Yellowstone National Park. The YVO scientific team's responses to the unfolding events in the scenario and to simulated requests for information by stakeholders and the media were assessed by (a) the exercise organizers; (b) several non-YVO scientists, who observed and queried participants, and took notes throughout the exercise; and (c) the participants themselves, who kept logs of their actions during the exercise and later participated in a group debriefing session and filled out detailed questionnaires. These evaluations were tabulated, interpreted, and summarized for this report, and on the basis of this information, recommendations have been made. Overall, the YVO teams performed their jobs very well. The exercise revealed that YVO scientists were able to successfully provide critical hazards information, issue information statements, and appropriately raise alert levels during a fast-moving crisis. Based on the exercise, it is recommended that several measures be taken to increase YVO effectiveness during a crisis: 1. Improve role clarification within and between YVO science teams. 2. Improve communications tools and protocols for data-sharing and consensus-building among YVO scientists, who are geographically and administratively dispersed among various institutions across the United States. 3. Familiarize YVO staff with Incident Command System (ICS) procedures and protocols, and provide more in

  14. The interest of cartography for a better perception and management of volcanic risk: From scientific to social representations: The case of Mt. Pelée volcano, Martinique (Lesser Antilles)

    Science.gov (United States)

    Leone, Frédéric; Lesales, Thierry

    2009-10-01

    The study develops an innovative GIS-based integrated approach for the assessment of a comprehensive volcanic risk. This is based on a four-step methodology which has been developed at Mt. Pelée volcano, in Martinique, a French island in the Lesser Antilles. The first stage of the methodological framework integrates the spatial extent of volcanic hazards for a maximal credible eruptive scenario. The second stage covers an assessment of the elements (especially the buildings) that may be affected in the event of an eruption and defines their level of damages by given volcanic hazards. A computerized analysis leads to the definition of an index for the risk of total loss in a 500-meter grid. The third stage consists of designing regulative land use maps which should orient and limit the occupation of areas exposed to severe hazards. Finally, the fourth stage, based on survey data, includes a spatial assessment of collective representations for a future eruption by the surrounding communities. These maps turn out to be powerful communication tools which help planners and disaster authorities in mitigating damages from volcanic hazards. They can contribute to enhance the perception of volcanic risk in Martinique.

  15. An investigation of vegetation and other Earth resource/feature parameters using LANDSAT and other remote sensing data. 1: LANDSAT. 2: Remote sensing of volcanic emissions. [New England forest and emissions from Mt. St. Helens and Central American volcanoes

    Science.gov (United States)

    Birnie, R. W.; Stoiber, R. E. (Principal Investigator)

    1981-01-01

    A fanning technique based on a simplistic physical model provided a classification algorithm for mixture landscapes. Results of applications to LANDSAT inventory of 1.5 million acres of forest land in Northern Maine are presented. Signatures for potential deer year habitat in New Hampshire were developed. Volcanic activity was monitored in Nicaragua, El Salvador, and Guatemala along with the Mt. St. Helens eruption. Emphasis in the monitoring was placed on the remote sensing of SO2 concentrations in the plumes of the volcanoes.

  16. Eruption parameters elicitation for volcanoes in Ethiopia and Kenya Informing a World Bank GFDRR project on volcanic threat in sub-Saharan Africa

    Science.gov (United States)

    Jenkins, Susanna; Lark, Murray; Loughlin, Sue; Fontijn, Karen; Mather, Tamsin; Pyle, David; Lewi, Elias; Yirgu, Gezahegn; Vye-Brown, Charlotte; Sparks, Steve

    2016-04-01

    Despite large numbers of very visible active volcanoes in sub-Saharan Africa, data about eruptions are limited compared to elsewhere in the world. We present the method and findings from elicitations carried out to characterise likely future eruptions in the region as part of a World Bank GFDRR risk profiling project for sub-Saharan Africa. The purpose of the elicitations was to better understand the characteristics and frequencies of explosive eruptions at volcanoes in Ethiopia and Kenya. The elicitations will provide source parameters for tephra fall modelling at select volcanoes in Ethiopia (Aluto, Corbetti, Fentale) and Kenya (Menegai, Longonot, Suswa). There were two stages of elicitation: 1) a 'sanity check' of initial assumptions around likely eruption style, magnitude and frequency for the six selected volcanoes; 2) a formal SHELF (SHeffield ELicitation Framework) elicitation that centred round establishing frequency-magnitude relationships for the volcanoes. The elicitation suggested that explosive eruptions at Aluto and Corbetti were less likely than at the other volcanoes, although the uncertainty was significant. Menengai and Rungwe volcano in Tanzania (elicited as an analogue for Fentale, Longonot and Suswa volcanoes) were characterised by approximately similar probabilities of eruption. However, Rungwe was considered more likely to produce larger explosive (VEI ≥ 4) eruptions than Menengai. Elicitation discussions highlighted the knowledge and data gaps for African volcanoes and raised important questions around whether gaps in the eruption record were real and related to changing regimes at the volcanoes over time or if they were a function of under-recording or lack of preservation. Further investigation is therefore needed to validate the findings of the elicitation. It is hoped that continued collaboration with local partners and studies within the ongoing NERC-funded RiftVolc project will address these issues and help to improve our knowledge

  17. Volcanic hazard management in dispersed volcanism areas

    Science.gov (United States)

    Marrero, Jose Manuel; Garcia, Alicia; Ortiz, Ramon

    2014-05-01

    Traditional volcanic hazard methodologies were developed mainly to deal with the big stratovolcanoes. In such type of volcanoes, the hazard map is an important tool for decision-makers not only during a volcanic crisis but also for territorial planning. According to the past and recent eruptions of a volcano, all possible volcanic hazards are modelled and included in the hazard map. Combining the hazard map with the Event Tree the impact area can be zoned and defining the likely eruptive scenarios that will be used during a real volcanic crisis. But in areas of disperse volcanism is very complex to apply the same volcanic hazard methodologies. The event tree do not take into account unknown vents, because the spatial concepts included in it are only related with the distance reached by volcanic hazards. The volcanic hazard simulation is also difficult because the vent scatter modifies the results. The volcanic susceptibility try to solve this problem, calculating the most likely areas to have an eruption, but the differences between low and large values obtained are often very small. In these conditions the traditional hazard map effectiveness could be questioned, making necessary a change in the concept of hazard map. Instead to delimit the potential impact areas, the hazard map should show the expected behaviour of the volcanic activity and how the differences in the landscape and internal geo-structures could condition such behaviour. This approach has been carried out in La Palma (Canary Islands), combining the concept of long-term hazard map with the short-term volcanic scenario to show the expected volcanic activity behaviour. The objective is the decision-makers understand how a volcanic crisis could be and what kind of mitigation measurement and strategy could be used.

  18. Contrasting records from mantle to surface of Holocene lavas of two nearby arc volcanic complexes: Caburgua-Huelemolle Small Eruptive Centers and Villarrica Volcano, Southern Chile

    Science.gov (United States)

    Morgado, E.; Parada, M. A.; Contreras, C.; Castruccio, A.; Gutiérrez, F.; McGee, L. E.

    2015-11-01

    Most of the small eruptive centers of the Andean Southern Volcanic Zone are built over the Liquiñe-Ofqui Fault Zone (LOFZ), a NS strike-slip (> 1000 km length) major structure, and close to large stratovolcanoes. This contribution compares textural features, compositional parameters, and pre- and syn-eruptive P,T conditions, between basaltic lavas of the Caburgua-Huelemolle Small Eruptive Centers (CHSEC) and the 1971 basaltic andesite lava of the Villarrica Volcano located 10 km south of the CHSEC. Olivines and clinopyroxenes occur as phenocrysts and forming crystal clots of the studied lavas. They do not markedly show compositional differences, except for the more scattered composition of the CHSEC clinopyroxenes. Plagioclase in CHSEC lavas mainly occur as phenocrysts or as microlites in a glass-free matrix. Two groups of plagioclase phenocrysts were identified in the 1971 Villarrica lava based on crystal size, disequilibrium features and zonation patterns. Most of the CHSEC samples exhibit higher LaN/YbN and more scattered Sr-Nd values than 1971 Villarrica lava samples, which are clustered at higher 143Nd/144Nd values. Pre-eruptive temperatures of the CHSEC-type reservoir between 1162 and 1165 ± 6 °C and pressures between 10.8 and 11.4 ± 1.7 kb consistent with a deep-seated reservoir were obtained from olivine-augite phenocrysts. Conversely, olivine-augite phenocrysts of 1971 Villarrica lava samples record pre-eruptive conditions of two stages or pauses in the magma ascent to the surface: 1208 ± 6 °C and 6.3-8.1 kb ± 1.7 kb (deep-seated reservoir) and 1164-1175 ± 6 °C and ≤ 1.4 kb (shallow reservoir). At shallow reservoir conditions a magma heating prior to the 1971 Villarrica eruption is recorded in plagioclase phenocrysts. Syn-eruptive temperatures of 1081-1133 ± 6 °C and 1123-1148 ± 6 °C were obtained in CHSEC and 1971 Villarrica lava, respectively using equilibrium olivine-augite microlite pairs. The LOFZ could facilitate a direct transport to

  19. Hawaii's volcanoes revealed

    Science.gov (United States)

    Eakins, Barry W.; Robinson, Joel E.; Kanamatsu, Toshiya; Naka, Jiro; Smith, John R.; Takahashi, Eiichi; Clague, David A.

    2003-01-01

    Hawaiian volcanoes typically evolve in four stages as volcanism waxes and wanes: (1) early alkalic, when volcanism originates on the deep sea floor; (2) shield, when roughly 95 percent of a volcano's volume is emplaced; (3) post-shield alkalic, when small-volume eruptions build scattered cones that thinly cap the shield-stage lavas; and (4) rejuvenated, when lavas of distinct chemistry erupt following a lengthy period of erosion and volcanic quiescence. During the early alkalic and shield stages, two or more elongate rift zones may develop as flanks of the volcano separate. Mantle-derived magma rises through a vertical conduit and is temporarily stored in a shallow summit reservoir from which magma may erupt within the summit region or be injected laterally into the rift zones. The ongoing activity at Kilauea's Pu?u ?O?o cone that began in January 1983 is one such rift-zone eruption. The rift zones commonly extend deep underwater, producing submarine eruptions of bulbous pillow lava. Once a volcano has grown above sea level, subaerial eruptions produce lava flows of jagged, clinkery ?a?a or smooth, ropy pahoehoe. If the flows reach the ocean they are rapidly quenched by seawater and shatter, producing a steep blanket of unstable volcanic sediment that mantles the upper submarine slopes. Above sea level then, the volcanoes develop the classic shield profile of gentle lava-flow slopes, whereas below sea level slopes are substantially steeper. While the volcanoes grow rapidly during the shield stage, they may also collapse catastrophically, generating giant landslides and tsunami, or fail more gradually, forming slumps. Deformation and seismicity along Kilauea's south flank indicate that slumping is occurring there today. Loading of the underlying Pacific Plate by the growing volcanic edifices causes subsidence, forming deep basins at the base of the volcanoes. Once volcanism wanes and lava flows no longer reach the ocean, the volcano continues to submerge, while

  20. Volcano seismology

    Science.gov (United States)

    Chouet, B.

    2003-01-01

    A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with wide dynamic range, and development of new powerful analysis techniques, rapid progress is being made toward a synthesis of high-quality seismic data to develop a coherent model of eruption mechanics. Examples of recent advances are: (1) high-resolution tomography to image subsurface volcanic structures at scales of a few hundred meters; (2) use of small-aperture seismic antennas to map the spatio-temporal properties of long-period (LP) seismicity; (3) moment tensor inversions of very-long-period (VLP) data to derive the source geometry and mass-transport budget of magmatic fluids; (4) spectral analyses of LP events to determine the acoustic properties of magmatic and associated hydrothermal fluids; and (5) experimental modeling of the source dynamics of volcanic tremor. These promising advances provide new insights into the mechanical properties of volcanic fluids and subvolcanic mass-transport dynamics. As new seismic methods refine our understanding of seismic sources, and geochemical methods better constrain mass balance and magma behavior, we face new challenges in elucidating the physico-chemical processes that cause volcanic unrest and its seismic and gas-discharge manifestations. Much work remains to be done toward a synthesis of seismological, geochemical, and petrological observations into an integrated model of volcanic behavior. Future important goals must include: (1) interpreting the key types of magma movement, degassing and boiling events that produce characteristic seismic phenomena; (2) characterizing multiphase fluids in subvolcanic

  1. Frequency-dependent seismic coda-attenuation imaging of volcanic geomorphology: from debris flows at Mount St. Helens volcano to cross-faulting at Campi Flegrei caldera.

    Science.gov (United States)

    De Siena, Luca; Gabrielli, Simona; Spagnolo, Matteo

    2017-04-01

    The stochastic loss of energy measured using the later portion of seismic recordings (coda) can be used to image and monitor geomorphology in volcanoes, once appropriate sensitivity kernels for the application of attenuation tomography have been developed. The use of this advanced seismic method with GIS/InSAR techniques is an unexplored field, which is receiving increasing attention in volcano-seismology. By using this integrated approach we can image structure and monitor dynamics of the debris flow that followed the 1980 explosive eruption of Mount St. Helens (US) volcano at resolution similar to that of remote sensing data, and depths of Italy, the results provide a novel perspective on the links between deep fluid migration and surface structures. The implications of the proposed approach on volcano monitoring are evident.

  2. Experimental studies of anomalous radon activity in the Tlamacas Mountain, Popocatepetl Volcano area, México: new tools to study lithosphere-atmosphere coupling for forecasting volcanic and seismic events

    Directory of Open Access Journals (Sweden)

    Jose Antonio Lopez Cruz Abeyro

    2012-04-01

    Full Text Available

    This study presents and discusses the results of soil radon monitoring at three different volcano sites and one reference site, from December 2007 to January 2009. This relates to the activity of the Popocatepetl Volcano and a radon survey and gamma-ray spectrometry in the area between Paso de Cortes and Tlamacas Mountain, and in the adjacent regions. The results are applied to the aspects of atmosphere electricity and lithosphere-atmosphere coupling in relation to the forecasting of volcano and earthquake activity. The monitoring of radon release reveals a decrease in radon concentration (down to total suppression with approaching moderate volcanic eruptions. The behavior of the radon activity at the Tlamacas site is more apparent, compared to other observational sites. The average level of radon release observed at the Tlamacas site is much higher, with some characteristic variations. Both the radon survey and gamma-ray spectrometry indicate intensive diffusion radon emission localized in the area of Tlamacas Mountain. The average radon concentration in the area of Tlamacas is about 10-20-fold greater than the background volcano values. The new concept of lithosphere-atmosphere coupling is presented: intensive radon release in high elevated areas shortens and modifies the Earth-to-thunderclouds electric circuit, which provokes microdischarges into the air close to the ground, attracting lightning discharges. This concept attempts to explain in a new way the noise-like geomagnetic emissions registered before major earthquakes, and it promotes interest for the study of thunderstorm activity in seismo-active zones, as a promising instrument for earthquake forecasting.

  3. Catalogue of Icelandic Volcanoes

    Science.gov (United States)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Gudmundsson, Magnus T.; Vogfjord, Kristin; Pagneux, Emmanuel; Oddsson, Bjorn; Barsotti, Sara; Karlsdottir, Sigrun

    2016-04-01

    The Catalogue of Icelandic Volcanoes is a newly developed open-access web resource in English intended to serve as an official source of information about active volcanoes in Iceland and their characteristics. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the effort of FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite. Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene (the time since the end of the last glaciation - approximately the last 11,500 years). In the last 50 years, over 20 eruptions have occurred in Iceland displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and the distribution lava and tephra. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in numerous scientific papers and other publications. In 2010, the International Civil Aviation Organisation (ICAO) funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU through the FP7 project FUTUREVOLC. The Catalogue of Icelandic Volcanoes is a collaboration of the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Civil Protection Department of the National Commissioner of the Iceland Police, with contributions from a large number of specialists in Iceland and elsewhere. The Catalogue is built up of chapters with texts and various

  4. Exploring Hawaiian Volcanism

    Science.gov (United States)

    Poland, Michael P.; Okubo, Paul G.; Hon, Ken

    2013-02-01

    In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai`i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO's founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists' understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

  5. Exploring Hawaiian volcanism

    Science.gov (United States)

    Poland, Michael P.; Okubo, Paul G.; Hon, Ken

    2013-01-01

    In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai‘i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO’s founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists’ understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

  6. Preliminary volcano-hazard assessment for Iliamna Volcano, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Miller, Thomas P.

    1999-01-01

    Iliamna Volcano is a 3,053-meter-high, ice- and snow-covered stratovolcano in the southwestern Cook Inlet region about 225 kilometers southwest of Anchorage and about 100 kilometers northwest of Homer. Historical eruptions of Iliamna Volcano have not been positively documented; however, the volcano regularly emits steam and gas, and small, shallow earthquakes are often detected beneath the summit area. The most recent eruptions of the volcano occurred about 300 years ago, and possibly as recently as 90-140 years ago. Prehistoric eruptions have generated plumes of volcanic ash, pyroclastic flows, and lahars that extended to the volcano flanks and beyond. Rock avalanches from the summit area have occurred numerous times in the past. These avalanches flowed several kilometers down the flanks and at least two large avalanches transformed to cohesive lahars. The number and distribution of known volcanic ash deposits from Iliamna Volcano indicate that volcanic ash clouds from prehistoric eruptions were significantly less voluminous and probably less common relative to ash clouds generated by eruptions of other Cook Inlet volcanoes. Plumes of volcanic ash from Iliamna Volcano would be a major hazard to jet aircraft using Anchorage International Airport and other local airports, and depending on wind direction, could drift at least as far as the Kenai Peninsula and beyond. Ashfall from future eruptions could disrupt oil and gas operations and shipping activities in Cook Inlet. Because Iliamna Volcano has not erupted for several hundred years, a future eruption could involve significant amounts of ice and snow that could lead to the formation of large lahars and downstream flooding. The greatest hazards in order of importance are described below and shown on plate 1.

  7. Volcano-hazard zonation for San Vicente volcano, El Salvador

    Science.gov (United States)

    Major, J.J.; Schilling, S.P.; Pullinger, C.R.; Escobar, C.D.; Howell, M.M.

    2001-01-01

    San Vicente volcano, also known as Chichontepec, is one of many volcanoes along the volcanic arc in El Salvador. This composite volcano, located about 50 kilometers east of the capital city San Salvador, has a volume of about 130 cubic kilometers, rises to an altitude of about 2180 meters, and towers above major communities such as San Vicente, Tepetitan, Guadalupe, Zacatecoluca, and Tecoluca. In addition to the larger communities that surround the volcano, several smaller communities and coffee plantations are located on or around the flanks of the volcano, and major transportation routes are located near the lowermost southern and eastern flanks of the volcano. The population density and proximity around San Vicente volcano, as well as the proximity of major transportation routes, increase the risk that even small landslides or eruptions, likely to occur again, can have serious societal consequences. The eruptive history of San Vicente volcano is not well known, and there is no definitive record of historical eruptive activity. The last significant eruption occurred more than 1700 years ago, and perhaps long before permanent human habitation of the area. Nevertheless, this volcano has a very long history of repeated, and sometimes violent, eruptions, and at least once a large section of the volcano collapsed in a massive landslide. The oldest rocks associated with a volcanic center at San Vicente are more than 2 million years old. The volcano is composed of remnants of multiple eruptive centers that have migrated roughly eastward with time. Future eruptions of this volcano will pose substantial risk to surrounding communities.

  8. Volcanic eruptions observed with infrasound

    Science.gov (United States)

    Johnson, Jeffrey B.; Aster, Richard C.; Kyle, Philip R.

    2004-07-01

    Infrasonic airwaves produced by active volcanoes provide valuable insight into the eruption dynamics. Because the infrasonic pressure field may be directly associated with the flux rate of gas released at a volcanic vent, infrasound also enhances the efficacy of volcanic hazard monitoring and continuous studies of conduit processes. Here we present new results from Erebus, Fuego, and Villarrica volcanoes highlighting uses of infrasound for constraining quantitative eruption parameters, such as eruption duration, source mechanism, and explosive gas flux.

  9. 火山地层学与火山架构:以长白山火山为例%Volcanostratigraphy and Volcanic Architecture of the Changbaishan Volcanos, NE China

    Institute of Scientific and Technical Information of China (English)

    王璞珺; 衣健; 陈崇阳; 王岩泉

    2013-01-01

    将长白山火山喷出物按成岩方式和岩相可分为柱状节理熔岩、火山碎屑流和火山泥石流等20种基本类型,它们均可构成可识别的19种火山地层单元.火山架构是由被火山地层界面所围限的诸多基本地层单元叠置而成.一个复杂的火山组合体,可以通过界面识别,拆分成若干火山地层单元,从而实现对火山堆积体的分解描述和整体认知.基性火山喷发区常见的5种火山架构(单源火山田、洪泛玄武岩田、熔岩盾火山、中心式火山和层状复合火山),在长白山地区相继发育.本区火山灾害可分为原发和次生2种.原发性灾害指火山再次喷发引发的灾害,巨量天池水可沿火山断裂下渗,使气水-岩浆喷发的可能性和爆炸强度增加,同时还能引发火山泥石流.次生灾害主要源于火山碎屑堆积物的再搬运和熔岩火山体的崩塌.熔岩火山在本区分布最广,但其底座常为3~7 m厚的松散沉积层,这犹如坐落在软地基之上的摩天大厦,是很不稳定的火山架构.熔岩体下伏的这些风化壳型松散层,只要发生流变或差异性沉陷,就会引发山体滑坡和山崩.因此,加强相关基础地质调查,对事关国计民生的重点区段开展次生火山灾害风险评估,势在必行.%Twenty types of volcanic materials ejected from Changbaishan volcanos were classified, such as columnar joint, pyroclastic flow deposits and lahars. Each of them can comprise a stratigraphic unit recognizable in the volcanic successions. Volcanic architectures are composed of these volcanic units bounded by some kind of eruption surfaces or unconformities. Monogenetic volcano fields, flood basalt field, lava shield volcanos, central volcanos and stratovolcanos described by Walker (2000) seem to develop successively from Miocene to Holocene in the area of Changbaishan volcanos. The potential volcanic hazards including both primary and secondary ones should be concerned

  10. Italian Volcano Supersites

    Science.gov (United States)

    Puglisi, G.

    2011-12-01

    Volcanic eruptions are among the geohazards that may have a substantial economic and social impact, even at worldwide scale. Large populated regions are prone to volcanic hazards worldwide. Even local phenomena may affect largely populated areas and in some cases even megacities, producing severe economic losses. On a regional or global perspective, large volcanic eruptions may affect the climate for years with potentially huge economic impacts, but even relatively small eruptions may inject large amounts of volcanic ash in the atmosphere and severely affect air traffic over entire continents. One of main challenges of the volcanological community is to continuously monitor and understand the internal processes leading to an eruption, in order to give substantial contributions to the risk reduction. Italian active volcanoes constitute natural laboratories and ideal sites where to apply the cutting-edge volcano observation systems, implement new monitoring systems and to test and improve the most advanced models and methods for investigate the volcanic processes. That's because of the long tradition of volcanological studies resulting into long-term data sets, both in-situ and from satellite systems, among the most complete and accurate worldwide, and the large spectrum of the threatening volcanic phenomena producing high local/regional/continental risks. This contribution aims at presenting the compound monitoring systems operating on the Italian active volcanoes, the main improvements achieved during the recent studies direct toward volcanic hazard forecast and risk reductions and the guidelines for a wide coordinated project aimed at applying the ideas of the GEO Supersites Initiative at Mt. Etna and Campi Flegrei / Vesuvius areas.

  11. Catastrophic volcanic collapse: relation to hydrothermal processes.

    Science.gov (United States)

    López, D L; Williams, S N

    1993-06-18

    Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.

  12. ANCIENT VOLCANOES AND TECTONIC STRUCTURES OF A RELIEF OF MARS

    Directory of Open Access Journals (Sweden)

    S. G. Pugacheva

    2014-01-01

    Full Text Available In article the basic geological and morphological features of a volcanic relief of a surface of a planet Mars are considered. The volcanic relief of a planet represents relic ancient shield volcanoes, linear forms of volcanic mountains, areal and central lava flooding, radial and concentric breaks. Results of researches of morphology of volcanic and tectonic formations of a relief of Mars are given in article. On materials of shooting of a surface of Mars spacecrafts constructed hypsometric high-rise profiles of volcanoes and average steepness of slopes are defined. The relative age of volcanoes and volcanic plains is estimated on density of shock craters.

  13. Insights on volcanic behaviour from the 2015 July 23-24 T-phase signals generated by eruptions at Kick-'em-Jenny Submarine Volcano, Grenada, Lesser Antilles

    Science.gov (United States)

    Dondin, F. J. Y.; Latchman, J. L.; Robertson, R. E. A.; Lynch, L.; Stewart, R.; Smith, P.; Ramsingh, C.; Nath, N.; Ramsingh, H.; Ash, C.

    2015-12-01

    Kick-'em-Jenny volcano (KeJ) is the only known active submarine volcano in the Lesser Antilles Arc. Since 1939, the year it revealed itself, and until the volcano-seismic unrest of 2015 July 11-25 , the volcano has erupted 12 times. Only two eruptions breached the surface: 1939, 1974. The volcano has an average eruption cycle of about 10-11 years. Excluding the Montserrat, Soufrière Hills, KeJ is the most active volcano in the Lesser Antilles arc. The University of the West Indies, Seismic Research Centre (SRC) has been monitoring KeJ since 1953. On July 23 and 24 at 1:42 am and 0:02 am local time, respectively, the SRC recorded T-phase signals , considered to have been generated by KeJ. Both signals were recorded at seismic stations in and north of Grenada: SRC seismic stations as well as the French volcano observatories in Guadeloupe and Martinique, Montserrat Volcano Observatory, and the Puerto Rico Seismic Network. These distant recordings, along with the experience of similar observations in previous eruptions, allowed the SRC to confirm that two explosive eruptions occurred in this episode at KeJ. Up to two days after the second eruption, when aerial surveillance was done, there was no evidence of activity at the surface. During the instrumental era, eruptions of the KeJ have been identified from T-phases recorded at seismic stations from Trinidad, in the south, to Puerto Rico, in the north. In the 2015 July eruption episode, the seismic station in Trinidad did not record T-phases associated with the KeJ eruptions. In this study we compare the T-phase signals of 2015 July with those recorded in KeJ eruptions up to 1974 to explore possible causative features for the T-phase recording pattern in KeJ eruptions. In particular, we investigate the potential role played by the Sound Fixing and Ranging (SOFAR) layer in influencing the absence of the T-phase on the Trinidad seismic station during this eruption.

  14. Petrography and geochemistry of achnelithic tephra from Las Herrerías Volcano (Calatrava volcanic field, Spain): Formation of nephelinitic achneliths and post-depositional glass alteration

    Science.gov (United States)

    Carracedo-Sánchez, M.; Sarrionandia, F.; Arostegui, J.; Errandonea-Martin, J.; Gil-Ibarguchi, J. I.

    2016-11-01

    We present the results of a petrographic and geochemical study carried out on a layer of achnelithic tephra outcropping at the base of the volcanic cone of Las Herrerías (Miocene-Quaternary volcanic region of Campo de Calatrava, Spain). The tephra, with a composition of nephelinite and ash (volcanic maar lake. Afterwards, there was no more water circulation through the achnelithic tephra, which was sealed from water by overlying hydrovolcanic tuff deposits. It was this isolation that made possible the preservation of glass to the present day.

  15. The Birimian volcanism in the northeastern Ivory-Coast, evidence for two distinct volcano-tectonic phases in the geodynamical evolution during the Palaeo-Proterozoic; Le volcanisme birimien du nord-est de la Cote-d`Ivoire, mise en evidence de deux phases volcano-tectoniques distinctes dans l`evolution geodynamique du Paleoproterozoique

    Energy Technology Data Exchange (ETDEWEB)

    Pouclet, A.; Vidal, M. [Orleans Univ., 45 (France); Delor, C.; Simeon, Y. [Bureau de Recherches Geologiques et Minieres (BRGM), 45 - Orleans (France); Alric, G.

    1996-12-31

    In the northeastern Ivory-Coast, volcanic formations having different geochemical features are located in the Haute-Comoe volcano-sedimentary Birimian terrains (Palaeo-Proterozoic). They consist of tholeiites belonging to greenstone belts and showing an oceanic magmatic signature, andesitic calc-alkaline lavas interbedded in the sediments of the Haute-Comoe Basin and related to an active margin-type magmatic genesis, and rhyodacitic intrusions spatially and geochemically linked to granitoid plutons. The magmatic characterization, in terms of geotectonic contexts leads to the following scheme: formation of the greenstone belts in a juvenile oceanic context with building of oceanic plateau (2.195 Ga), genesis of granitoid batholites with metamorphose the belts and beget a first continental crust (2.15 Ga), opening of a sedimentary basin in a shear-zone corridor with local production of calc-alkaline volcanism due to heat transfer along a major lithospheric fault (2.15 - 2.10 Ga), shortening of the basin with leucogranite intrusions in the same transcurrent context (2.09 Ga). This geodynamical scheme takes account of the distinction between two major volcano-tectonic phases: a tholeiitic phase with the greenstone belt formation and then, a calc-alkaline phase linked to the structural evolution of the sedimentary basin. This model could be applied to other Ivory-Coast Birimian terrains, but it is necessary to distinguish the volcanics and the sediments belonging to the greenstone belts and those of the basins which were emplaced between the batholiths. (authors). 78 refs., 9 figs., 1 tab.

  16. Exploration of the Rotokawa geothermal field, Taupo volcanic zone, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Browne, P.R.L. (Univ. of Auckland (New Zealand))

    1988-11-10

    The Rotokawa geothermal field is located 7 km east of Wairakei, New Zealand, and has been investigated for its sulphur resources and power potential over the past 50 years. Exploration of the field has slow and mostly unsystematic. The depths of the drill holes are less than 50 m until 1964. Since 1965 the exploration has been carried out systematically. Three, one and four exploration wells were drilled in 1965-66, 1977, and 1984-86 respectively. Finding Jurassic greywackes and argillites at a depth of 2200 m below a thick (ca. 900 m)sequence of two pyroxene andesite lava flows had an important significance, because the Jurassic rocks are the basement rocks for the North Island. The Rotokawa geothermal field represents an important resource with an assessed potential of 49 MW (proven), 100 MW (probable) and 200 MW (possible), though these figures are considered to be probably optimistic. Further exploratory drilling is needed. The main development problems at this stage are: (1) encountering good subsurface permeability, (2) identifying and combating corrosive CO{sub 2}-rich fluids, (3) determining the most favorable reinjection conditions; this is a problem, ironically enhanced by the hot temperature and the consequently high silica contents of the thermal fluids, (4) establishing an acceptable development plan for the field which accommodates the requirements of both the sulphur mining interests, the power producers, and especially the Ngati Tahu maori owners of the land. 24 refs., 2 figs., 2 tabs.

  17. "Canary Islands, a volcanic window in the Atlantic Ocean": a 7 year effort of public awareness on volcano hazards and risk management

    Science.gov (United States)

    Rodríguez, Fátima; Calvo, David; Pérez, Nemesio M.; Padrón, Eleazar; Melián, Gladys; Padilla, Germán; Barrancos, José; Hernández, Pedro A.; Asensio-Ramos, María; Alonso, Mar

    2016-04-01

    "Canary Islands: A volcanic window in the Atlantic Ocean" is an educational program born from the need to inform and educate citizens residing in the Canary Islands on the various hazards associated to volcanic phenomena. The Canary Islands is the only territory of Spain that hosts active volcanism, as is shown by the 16 historical eruptions that have occurred throughout this territory, being the last one a submarine eruption taking place on October 12, 2011, offshore El Hierro Island. In the last 7 years, ITER as well as INVOLCAN have been performing an educative program focused on educating to the population about the benefits of a volcanic territory, volcanic hazards, how to reduce volcanic risk and the management of volcanic risk in the Canary Islands. "Canary Islands: A volcanic window in the Atlantic Ocean" consists of three units, the first two dedicated to the IAVCEI/UNESCO videos "Understanding Volcanic Hazards" and "Reducing Volcanic Risk" and the third one dedicated to the management of volcanic risk in the Canary Islands, as well as some other aspects of the volcanic phenomena. Generally the three units are shown consecutively on Tuesday, Wednesday and Thursday. This educative program has been roaming all around the 88 municipalities of the archipelago since this initiative started in 2008. The total number of attendees since then amounts to 18,911 people. The increase of assistance was constant until 2011, with annual percentages of 7.8, 17.1 and 20.9 respectively, regarding to ratio assistant/municipality. Despite the heterogeneity of the audience, the main audience is related to aged people of 45 years and older. This could be related to the memories of the recent eruptions occurred at La Palma Island in 1949 and 1971. It is important to point out that many of those people attending the educative program are representatives of local government (i.e. civil protection). Regarding the interest of the audience, the educational program attendees have

  18. "Mediterranean volcanoes vs. chain volcanoes in the Carpathians"

    Science.gov (United States)

    Chivarean, Radu

    2017-04-01

    Volcanoes have always represent an attractive subject for students. Europe has a small number of volcanoes and Romania has none active ones. The curricula is poor in the study of volcanoes. We want to make a parallel between the Mediterranean active volcanoes and the old extinct ones in the Oriental Carpathians. We made an comparison of the two regions in what concerns their genesis, space and time distribution, the specific relief and the impact in the landscape, consequences of their activities, etc… The most of the Mediterranean volcanoes are in Italy, in the peninsula in Napoli's area - Vezuviu, Campi Flegrei, Puzzoli, volcanic islands in Tirenian Sea - Ischia, Aeolian Islands, Sicily - Etna and Pantelleria Island. Santorini is located in Aegean Sea - Greece. Between Sicily and Tunisia there are 13 underwater volcanoes. The island called Vulcano, it has an active volcano, and it is the origin of the word. Every volcano in the world is named after this island, just north of Sicily. Vulcano is the southernmost of the 7 main Aeolian Islands, all volcanic in origin, which together form a small island arc. The cause of the volcanoes appears to be a combination of an old subduction event and tectonic fault lines. They can be considered as the origin of the science of volcanology. The volcanism of the Carpathian region is part of the extensive volcanic activity in the Mediterranean and surrounding regions. The Carpathian Neogene/Quaternary volcanic arc is naturally subdivided into six geographically distinct segments: Oas, Gutai, Tibles, Calimani, Gurghiu and Harghita. It is located roughly between the Carpathian thrust-and-fold arc to the east and the Transylvanian Basin to the west. It formed as a result of the convergence between two plate fragments, the Transylvanian micro-plate and the Eurasian plate. Volcanic edifices are typical medium-sized andesitic composite volcanoes, some of them attaining the caldera stage, complicated by submittal or peripheral domes

  19. Catalogue of Icelandic volcanoes

    Science.gov (United States)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Vogfjörd, Kristin; Tumi Gudmundsson, Magnus; Jonsson, Trausti; Oddsson, Björn; Reynisson, Vidir; Barsotti, Sara; Karlsdottir, Sigrun

    2015-04-01

    Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene. In the last 100 years, over 30 eruptions have occurred displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and their distribution. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in scientific papers and other publications. In 2010, the International Civil Aviation Organisation funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland (commenced in 2012), and the EU FP7 project FUTUREVOLC (2012-2016), establishing an Icelandic volcano Supersite. The Catalogue is a collaborative effort between the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Icelandic Civil Protection, with contributions from a large number of specialists in Iceland and elsewhere. The catalogue is scheduled for opening in the first half of 2015 and once completed, it will be an official publication intended to serve as an accurate and up to date source of information about active volcanoes in Iceland and their characteristics. The Catalogue is an open web resource in English and is composed of individual chapters on each of the volcanic systems. The chapters include information on the geology and structure of the volcano; the eruption history, pattern and products; the known precursory signals

  20. Volcanism on Mars. Chapter 41

    Science.gov (United States)

    Zimbelman, J. R.; Garry, W. B.; Bleacher, J. E.; Crown, D. A.

    2015-01-01

    Spacecraft exploration has revealed abundant evidence that Mars possesses some of the most dramatic volcanic landforms found anywhere within the solar system. How did a planet half the size of Earth produce volcanoes like Olympus Mons, which is several times the size of the largest volcanoes on Earth? This question is an example of the kinds of issues currently being investigated as part of the space-age scientific endeavor called "comparative planetology." This chapter summarizes the basic information currently known about volcanism on Mars. The volcanoes on Mars appear to be broadly similar in overall morphology (although, often quite different in scale) to volcanic features on Earth, which suggests that Martian eruptive processes are not significantly different from the volcanic styles and processes on Earth. Martian volcanoes are found on terrains of different age, and Martian volcanic rocks are estimated to comprise more than 50% of the Martian surface. This is in contrast to volcanism on smaller bodies such as Earth's Moon, where volcanic activity was mainly confined to the first half of lunar history (see "Volcanism on the Moon"). Comparative planetology supports the concept that volcanism is the primary mechanism for a planetary body to get rid of its internal heat; smaller bodies tend to lose their internal heat more rapidly than larger bodies (although, Jupiter's moon Io appears to contradict this trend; Io's intense volcanic activity is powered by unique gravitational tidal forces within the Jovian system; see "Volcanism on Io"), so that volcanic activity on Mars would be expected to differ considerably from that found on Earth and the Moon.

  1. Record of Volcanism Since 7000 B.C. from the GISP2 Greenland Ice Core and Implications for the Volcano-Climate System.

    Science.gov (United States)

    Zielinski, G A; Mayewski, P A; Meeker, L D; Whitlow, S; Twickler, M S; Morrison, M; Meese, D A; Gow, A J; Alley, R B

    1994-05-13

    Sulfate concentrations from continuous biyearly sampling of the GISP2 Greenland ice core provide a record of potential climate-forcing volcanism since 7000 B.C. Although 85 percent of the events recorded over the last 2000 years were matched to documented volcanic eruptions, only about 30 percent of the events from 1 to 7000 B.C. were matched to such events. Several historic eruptions may have been greater sulfur producers than previously thought. There are three times as many events from 5000 to 7000 B.C. as over the last two millennia with sulfate deposition equal to or up to five times that of the largest known historical eruptions. This increased volcanism in the early Holocene may have contributed to climatic cooling.

  2. The Cenozoic Volcanoes in Northeast China

    Institute of Scientific and Technical Information of China (English)

    LIU Jiaqi; HAN Jingtai; GUO Zhengfu

    2002-01-01

    There are more than 600 Cenozoic volcanic cones and craters with abeut 50 000 km2of lava flows in northeast China, which formed many volcanic clusters and shown the features of the continental rift - type volcanoes. Most volcanic activities in this area, especially in the east part of Songliao graben, were usually controlled by rifts and faults with the main direction of NE / NNE in parallel and become younger from the central graben towards its both sides, especially to the east continental margin. It is revealed that the volcanism occurred in northeast China was as strong as that occurred in Japan during the Miocene and the Quaternary. The Quaternary basalt that is usually distributed along river valley is called "valley basalt"while Neogene basalt usually distributed in the top of mounts is called "high position basalt". These volcanoes and volcanic rocks are usually composed of alkaline basalts with ultramafic inclusions, except Changbaishan volcano that is built by trachyte and pantellerite.

  3. Volcano Preparedness

    Science.gov (United States)

    ... You might feel better to learn that an ‘active’ volcano is one that has erupted in the past ... miles away. If you live near a known volcano, active or dormant, following these tips will help you ...

  4. Deformation in volcanic areas: a numerical approach for their prediction in Teide volcano (Tenerife, Canary Islands); Deformaciones en areas volcanicas: una aproximacin numerica para su prediccion en el volcan Teide (Tenerife, Islas Canarias)

    Energy Technology Data Exchange (ETDEWEB)

    Charco, M.; Galan del Sastre, P.

    2011-07-01

    Active volcanic areas study comprises both, observation of physical changes in the natural media and the interpretation of such changes. Nowadays, the application of spatial geodetic techniques, such as GPS (Global Positioning System) or InSAR (Interferometry with Synthetic Aperture Radar), for deformation understanding in volcanic areas, revolutionizes our view of this geodetic signals. Deformation of the Earth's surface reflects tectonic, magmatic and hydrothermal processes at depth. In this way, the prediction of volcanic deformation through physical modelling provides a link between the observation and depth interior processes that could be crucial for volcanic hazards assessment. In this work, we develop a numerical model for elastic deformation study. The Finite Element Method (FEM) is used for the implementation of the numerical model. FEM allows to take into account different morphology, structural characteristics and the mechanical heterogeneities of the medium. Numerical simulations of deformation in Tenerife (Canary Islands) taking into account different medium hypothesis allow us to conclude that the accuracy of the predictions depends on how well the natural system is described. (Author) 22 refs.

  5. Volcanic hazards to airports

    Science.gov (United States)

    Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.

    2009-01-01

    Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by volcanic activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by volcanic activity, which indicates that volcanic hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by volcanic hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby volcanic activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by volcanic activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies

  6. Volcanostratigraphic Approach for Evaluation of Geothermal Potential in Galunggung Volcano

    Science.gov (United States)

    Ramadhan, Q. S.; Sianipar, J. Y.; Pratopo, A. K.

    2016-09-01

    he geothermal systems in Indonesia are primarily associated with volcanoes. There are over 100 volcanoes located on Sumatra, Java, and in the eastern part of Indonesia. Volcanostratigraphy is one of the methods that is used in the early stage for the exploration of volcanic geothermal system to identify the characteristics of the volcano. The stratigraphy of Galunggung Volcano is identified based on 1:100.000 scale topographic map of Tasikmalaya sheet, 1:50.000 scale topographic map and also geological map. The schematic flowchart for evaluation of geothermal exploration is used to interpret and evaluate geothermal potential in volcanic regions. Volcanostratigraphy study has been done on Galunggung Volcano and Talaga Bodas Volcano, West Java, Indonesia. Based on the interpretation of topographic map and analysis of the dimension, rock composition, age and stress regime, we conclude that both Galunggung Volcano and Talaga Bodas Volcano have a geothermal resource potential that deserve further investigation.

  7. Submarine seismic monitoring of El Hierro volcanic eruption with a 3C-geophone string: applying new acquisition and data processing techniques to volcano monitoring

    Science.gov (United States)

    Jurado, Maria Jose; Ripepe, Maurizio; Lopez, Carmen; Blanco, Maria Jose; Crespo, Jose

    2015-04-01

    A submarine volcanic eruption took place near the southernmost emerged land of the El Hierro Island (Canary Islands, Spain), from October 2011 to February 2012. The Instituto Geografico Nacional (IGN) seismic stations network evidenced seismic unrest since July 2011 and was a reference also to follow the evolution of the seismic activity associated with the volcanic eruption. Right after the eruption onset, in October 2011 a geophone string was deployed by the CSIC-IGN to monitor seismic activity. Monitoring with the seismic array continued till May 2012. The array was installed less than 2 km away from the new vol¬cano, next to La Restinga village shore in the harbor from 6 to 12m deep into the water. Our purpose was to record seismic activity related to the volcanic activity, continuously and with special interest on high frequency events. The seismic array was endowed with 8, high frequency, 3 component, 250 Hz, geophone cable string with a separation of 6 m between them. Each geophone consists on a 3-component module based on 3 orthogonal independent sensors that measures ground velocity. Some of the geophones were placed directly on the seabed, some were buried. Due to different factors, as the irregular characteristics of the seafloor. The data was recorded on the surface with a seismometer and stored on a laptop computer. We show how acoustic data collected underwater show a great correlation with the seismic data recorded on land. Finally we compare our data analysis results with the observed sea surface activity (ash and lava emission and degassing). This evidence is disclosing new and innovative tecniques on monitoring submarine volcanic activity. Reference Instituto Geográfico Nacional (IGN), "Serie El Hierro." Internet: http://www.ign.es/ign/resources /volcanologia/HIERRO.html [May, 17. 2013

  8. Subterranean fragmentation of magma during conduit initiation and evolution in the shallow plumbing system of the small-volume Jagged Rocks volcanoes (Hopi Buttes Volcanic Field, Arizona, USA)

    Science.gov (United States)

    Re, Giuseppe; White, James D. L.; Muirhead, James D.; Ort, Michael H.

    2016-08-01

    Monogenetic volcanoes have limited magma supply and lack long-lived sustained magma plumbing systems. They erupt once, often from multiple vents and sometimes over several years, and are rarely or never re-activated. Eruptive behavior is very sensitive to physical processes (e.g., volatile exsolution, magma-water interaction) occurring in the later stages of magma ascent at shallow crustal depths (flowing through dikes fragmented and conduits were formed. We have identified three main types of fragmental deposits, (1) buds (which emerge from dikes), (2) pyroclastic massifs, and (3) diatremes; these represent three different styles and intensities of shallow-depth magma fragmentation. They may develop successively and at different sites during the evolution of a monogenetic volcano. The deposits consist of a mixture of pyroclasts with varying degrees of welding and country-rock debris in various proportions. Pyroclasts are commonly welded together, but also reveal in places features consistent with phreatomagmatism, such as blocky shapes, dense groundmasses, and composite clasts (loaded and cored). The extent of fragmentation and the formation of subterranean open space controlled the nature of the particles and the architecture and geometry of these conduit structures and their deposits.

  9. Alaska volcanoes guidebook for teachers

    Science.gov (United States)

    Adleman, Jennifer N.

    2011-01-01

    Alaska’s volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 140 volcanoes, which have been active over the last 2 million years. About 90 of these volcanoes have been active within the last 10,000 years and more than 50 of these have been active since about 1700. The volcanoes in Alaska make up well over three-quarters of volcanoes in the United States that have erupted in the last 200 years. In fact, Alaska’s volcanoes erupt so frequently that it is almost guaranteed that an Alaskan will experience a volcanic eruption in his or her lifetime, and it is likely they will experience more than one. It is hard to imagine a better place for students to explore active volcanism and to understand volcanic hazards, phenomena, and global impacts. Previously developed teachers’ guidebooks with an emphasis on the volcanoes in Hawaii Volcanoes National Park (Mattox, 1994) and Mount Rainier National Park in the Cascade Range (Driedger and others, 2005) provide place-based resources and activities for use in other volcanic regions in the United States. Along the lines of this tradition, this guidebook serves to provide locally relevant and useful resources and activities for the exploration of numerous and truly unique volcanic landscapes in Alaska. This guidebook provides supplemental teaching materials to be used by Alaskan students who will be inspired to become educated and prepared for inevitable future volcanic activity in Alaska. The lessons and activities in this guidebook are meant to supplement and enhance existing science content already being taught in grade levels 6–12. Correlations with Alaska State Science Standards and Grade Level Expectations adopted by the Alaska State Department of Education and Early Development (2006) for grades six through eleven are listed at

  10. Facies volcánicas del depósito de avalancha de detritos del volcán Tata Sabaya, Andes Centrales Volcanic facies of the debris avalanche deposit of Tata Sabaya Volcano, Central Andes

    Directory of Open Access Journals (Sweden)

    Benigno Godoy

    2012-09-01

    evolution of a volcano. These flows are formed by edifice instability, which could be due to several factors such as the presence of hydrother-mally altered areas, climatic changes, earthquakes, shallow magma intrusions (cryptodomes and/or dykes and/or fault activity beneath or close to the volcano. The final product of this avalanche flow, known as debris avalanche deposit (DAD shows typical hummocky and closed drainage morphologies. More than 14 volcanic centers of the Central Andes have volcanic DAD's, being Tata Sabaya (Bolivia one of them. The collapse that has originated the deposit could have been generated by a combination of magmatic and seismic activity in the volcano. The deposit associated to the partial collapse of Tata Sabaya volcano is distributed on its lower southern flank and partially fills the north-western part of the Salar de Coipasa basin. The deposit covers a minimum area of 230 km² and has an estimated minimum volume of 6±1 km³. The deposit is formed by 6 different types of hummocks, according to their compositions: lavic, pyroclastic, sedimentary, mixed, pyroclastic breccia and basaltic-andesitic hummocks. Based on the predominant hummock type and the spatial distribution, the deposit has been divided into 6 different facies (Toreva Block Facies, Volcanic Hummocks Facies, Central Facies, Sedimentary Hummocks Facies, Mixed Facies and Pyroclastic Breccia Hummocks Facies. Taking into account the facies distribution and their characteristics, we infer the pre-collapse structure of the volcano.

  11. Phreatomagmatic and water-influenced Strombolian eruptions of a small-volume parasitic cone complex on the southern ringplain of Mt. Ruapehu, New Zealand: Facies architecture and eruption mechanisms of the Ohakune Volcanic Complex controlled by an unstable fissure eruption

    Science.gov (United States)

    Kósik, S.; Németh, K.; Kereszturi, G.; Procter, J. N.; Zellmer, G. F.; Geshi, N.

    2016-11-01

    The Ohakune Volcanic Complex is a late Pleistocene tuff ring - scoria/spatter cone complex located south of Ruapehu volcano. This small-volume volcano consists of an outer E-W elongated compound tuff ring edifice, three inner scoria-spatter cones and further volcanic depressions, located on the Ohakune Fault. We quantified accurately the variations of the eruptive styles and processes through time by systematic sampling of key stratigraphic marker beds at proximal and distal locations, and the determination of grain size distribution, componentry, density and vesicularity. Using a Digital Terrain Model coupled with stratigraphic data, we also determined the spatial distribution and volume of each identified unit and individual edifices within the Ohakune Volcanic Complex. Activity began with a shallow phreatomagmatic phase characterized by an almost continuous generation of a low eruptive column, accompanied by wet pyroclastic density currents, together with the ejection of juvenile fragments and accidental lithics from the surrounding country rocks. Subsequent activity was dominated by a variety of Strombolian eruptions exhibiting differing intensities that were at times disrupted by phreatic blasts or phreatomagmatic explosions due to the interaction with external water and/or sudden changes in magma discharge rate. At least three major vent-shifting events occurred during the eruption, which is demonstrated by the truncation of the initial tuff ring and the infilling of the truncated area by several coarse grained surge units. Our study indicates that approx. 12 × 106 m3 DRE magma erupted within maximum 2.5 to 5 months through multiple vents. The erupted magma ascended from a depth of 16-18 km, and reached the surface within approximately 50 h. Alternating eruption styles, frequent vent-shifting and a variety of emplacement mechanisms inferred from the deposits of the Ohakune Volcanic Complex demonstrate the unpredictable nature of small-volume volcanism

  12. Distinguishing contributions to diffuse CO2 emissions in volcanic areas from magmatic degassing and thermal decarbonation using soil gas 222Rn-δ13C systematics: Application to Santorini volcano, Greece

    Science.gov (United States)

    Parks, Michelle M.; Caliro, Stefano; Chiodini, Giovanni; Pyle, David M.; Mather, Tamsin A.; Berlo, Kim; Edmonds, Marie; Biggs, Juliet; Nomikou, Paraskevi; Raptakis, Costas

    2013-09-01

    Between January 2011 and April 2012, Santorini volcano (Greece) experienced a period of unrest characterised by the onset of detectable seismicity and caldera-wide uplift. This episode of inflation represented the first sizeable intrusion of magma beneath Santorini in the past 50 years. We employ a new approach using 222Rn-δ13C systematics to identify and quantify the source of diffuse degassing at Santorini during the period of renewed activity. Soil CO2 flux measurements were made across a network of sites on Nea Kameni between September 2010 and January 2012. Gas samples were collected in April and September 2011 for isotopic analysis of CO2 (δ13C), and radon detectors were deployed during September 2011 to measure (222Rn). Our results reveal a change in the pattern of degassing from the summit of the volcano (Nea Kameni) and suggest an increase in diffuse CO2 emissions between September 2010 and January 2012. High-CO2-flux soil gas samples have δ13C˜0‰. Using this value and other evidence from the literature we conclude that these CO2 emissions from Santorini were a mixture between CO2 sourced from magma, and CO2 released by the thermal or metamorphic breakdown of crustal limestone. We suggest that this mixing of magmatic and crustal carbonate sources may account more broadly for the typical range of δ13C values of CO2 (from ˜-4‰ to ˜+1‰) in diffuse volcanic and fumarole gas emissions around the Mediterranean, without the need to invoke unusual mantle source compositions. At Santorini a mixing model involving magmatic CO2 (with δ13C of -3±2‰ and elevated (222Rn)/CO2 ratios ˜105-106 Bqkg) and CO2 released from decarbonation of crustal limestone (with (222Rn)/CO2 ˜ 30-300 Bq kg-1, and δ13C of +5‰) can account for the δ13C and (222Rn)/CO2 characteristics of the 'high flux' gas source. This model suggests ˜60% of the carbon in the high flux deep CO2 end member is of magmatic origin. This combination of δ13C and (222Rn) measurements has

  13. Environmental impact of the 1.8 ka Taupo eruption, New Zealand: Landscape responses to a large-scale explosive rhyolite eruption

    Science.gov (United States)

    Manville, V.; Segschneider, B.; Newton, E.; White, J. D. L.; Houghton, B. F.; Wilson, C. J. N.

    2009-10-01

    Large-scale ignimbrite eruptions from rhyolitic caldera volcanoes can trigger geologically instantaneous changes in sedimentary systems over huge areas by either burying existing environments or overloading them with vast quantities of unconsolidated particulate material. The post-eruption readjustment of the landscape to such perturbations is one of the most dramatic processes in physical sedimentology, exemplified here by the 1.8 ka Taupo eruption in the central North Island of New Zealand. This eruption generated voluminous fall deposits, then climaxed with emplacement of a c. 30 km 3 non-welded ignimbrite over a near-circular area of c. 20 000 km 2. Approximately 90% of the area, but retrenchment of single thread rivers and a return to pre-eruption gradients and bedloads years to decades later. Typically the modern profile of many streams and rivers follow closely their pre-eruption profiles, and incision and erosion is overwhelmingly confined to the deposits of the eruption itself. Although the general remobilisation pattern is similar for all impacted river systems, detailed studies of the Waikato, Rangitaiki, Mohaka, Ngaruroro and Whanganui catchments show that the relative timing and scale of each eruption response phase differs between each catchment. These reflect differences in catchment physiography and hydrology, and the volume and type of pyroclastic material deposited in each. Ultimately, the landscape response reflects the relative spatial distributions of, and the volumetric ratios between, the volumes of pyroclastic debris, water, and accommodation space in the basin (cf. Kataoka and Manville, this volume).

  14. Estimating the volcanic emission rate and atmospheric lifetime of SO2 from space: a case study for Kīlauea volcano, Hawai`i

    Directory of Open Access Journals (Sweden)

    S. Beirle

    2014-08-01

    Full Text Available We present an analysis of SO2 column densities derived from GOME-2 satellite measurements for the Kīlauea volcano (Hawai`i for 2007–2012. During a period of enhanced degassing activity in March–November 2008, monthly mean SO2 emission rates and effective SO2 lifetimes are determined simultaneously from the observed downwind plume evolution and meteorological wind fields, without further model input. Kīlauea is particularly suited for quantitative investigations from satellite observations owing to the absence of interfering sources, the clearly defined downwind plumes caused by steady trade winds, and generally low cloud fractions. For March–November 2008, the effective SO2 lifetime is 1–2 days, and Kīlauea SO2 emission rates are 9–21 kt day−1, which is about 3 times higher than initially reported from ground-based monitoring systems.

  15. Determination of temporal changes in seismic velocity caused by volcanic activity in and around Hakone volcano, central Japan, using ambient seismic noise records

    Science.gov (United States)

    Yukutake, Yohei; Ueno, Tomotake; Miyaoka, Kazuki

    2016-12-01

    Autocorrelation functions (ACFs) for ambient seismic noise are considered to be useful tools for estimating temporal changes in the subsurface structure. Velocity changes at Hakone volcano in central Japan, where remarkable swarm activity has often been observed, were investigated in this study. Significant velocity changes were detected during two seismic activities in 2011 and 2013. The 2011 activity began immediately after the 2011 Tohoku-oki earthquake, suggesting remote triggering by the dynamic stress changes resulting from the earthquake. During the 2013 activity, which exhibited swarm-like features, crustal deformations were detected by Global Navigation Satellite System (GNSS) stations and tiltmeters, suggesting a pressure increment of a Mogi point source at a depth of 7 km and two shallow open cracks. Waveforms that were bandpass-filtered between 1 and 3 Hz were used to calculate ACFs using a one-bit correlation technique. Fluctuations in the velocity structure were obtained using the stretching method. A gradual decrease in the velocity structure was observed prior to the 2013 activity at the KOM station near the central cone of the caldera, which started after the onset of crustal expansion observed by the GNSS stations. Additionally, a sudden significant velocity decrease was observed at the OWD station near a fumarolic area just after the onset of the 2013 activity and the tilt changes. The changes in the stress and strain caused by the deformation sources were likely the main contributors to these decreases in velocity. The precursory velocity reduction at the KOM station likely resulted from the inflation of the deep Mogi source, whereas the sudden velocity decrease at the OWD station may reflect changes in the strain caused by the shallow open-crack source. Rapid velocity decreases were also detected at many stations in and around the volcano after the 2011 Tohoku-oki earthquake. The velocity changes may reflect the redistribution of hydrothermal

  16. Evidences of volcanic unrest on high-temperature fumaroles by satellite thermal monitoring: The case of Santa Ana volcano, El Salvador

    Science.gov (United States)

    Laiolo, M.; Coppola, D.; Barahona, F.; Benítez, J. E.; Cigolini, C.; Escobar, D.; Funes, R.; Gutierrez, E.; Henriquez, B.; Hernandez, A.; Montalvo, F.; Olmos, R.; Ripepe, M.; Finizola, A.

    2017-06-01

    On October 1st, 2005, Santa Ana volcano (El Salvador) underwent a VEI 3 phreatomagmatic eruption after approximately one century of rest. Casualties and damages to some of the local infrastructures and surrounding plantations were followed by the evacuation of the nearby communities. The analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) infrared data reveals that the main explosion was preceded by a one-year-long thermal unrest, associated to the development of a fumaroles field, located at the western rim of the summit crater lake. By combining space-based thermal flux and ground-based measurements (seismicity, sulfur emissions and lake temperatures), we suggest that the activity observed at Santa Ana between 2004 and 2005 was driven by the gradual intrusion of an undegassed magma body at a very shallow depth. Magma injection induced thermal anomalies associated with sustained degassing from the fumaroles field and promoted the interaction between the magmatic-hydrothermal system and the overlying water table. This process culminated into the VEI 3 phreatomagmatic eruption of October 2005 that strongly modified the shallow structure of the crater area. The subsequent three-years-long activity resulted from self-sealing of the fracture system and by the opening of a new fracture network directly connecting the deeper hydrothermal system with the crater lake. Our results show that satellite-based thermal data allow us to detect the expansion of the high-temperature fumarolic field. This may precede an explosive eruption and/or a lava dome extrusion. In particular, we show that thermal records can be analyzed with other geochemical (i.e. SO2 emissions) and geophysical (seismicity) data to track a shallow magmatic intrusion interacting with the surrounding hydrothermal system. This provides a remarkable support for volcano monitoring and eruption forecasting, particularly in remote areas where permanent ground data acquisition is hazardous, expensive

  17. Volcanic Zone, New Zealand

    Directory of Open Access Journals (Sweden)

    Graham J. Weir

    2001-01-01

    Full Text Available A conceptual model of the Taupo Volcanic Zone (TVZ is developed, to a depth of 25 km, formed from three constant density layers. The upper layer is formed from eruption products. A constant rate of eruption is assumed, which eventually implies a constant rate of extension, and a constant rate of volumetric creation in the middle and bottom layers. Tectonic extension creates volume which can accomodate magmatic intrusions. Spreading models assume this volume is distributed throughout the whole region, perhaps in vertical dykes, whereas rifting models assume the upper crust is thinned and the volume created lies under this upper crust. Bounds on the heat flow from such magmatic intrusions are calculated. Heat flow calculations are performed and some examples are provided which match the present total heat output from the TVZ of about 4200 MW, but these either have extension rates greater than the low values of about 8 ± 4 mm/a being reported from GPS measurements, or else consider extension rates in the TVZ to have varied over time.

  18. The Climate and Human Impacts of Major Explosive Volcanism AD670-730, A Multi-proxy Assessment

    Science.gov (United States)

    Gao, C.; Ludlow, F.

    2013-12-01

    Chronologically secure volcanic events can provide an important tool to improve ice core dating as well as our understanding of volcano-climate responses. However, there is a substantial lack of reference horizons for ice-core dating during the first millennium, excepting the Taupo (New Zealand, AD186×10) and Vesuvius (Italy, AD 79) eruptions. In this exploratory case-study, we use a total of 20 ice core records, 9 from the Arctic and 11 from the Antarctic, together with historical records to examine the occurrence and climatic impact of explosive volcanism, AD 670-730. Sulfate signals comparable in magnitude to the sizeable 1815 Tambora eruption are detected in all of the ice-core time series, with different cores attributing the timing of eruptions to AD 676×2, 688×2, or 700×2, respectively. Historical records of widespread frost damage, anomalously warm winters, drought, famine and mortality from Chinese, European and Middle Eastern chronicles suggest substantial climate and social perturbations during AD 677-685 and AD 699-709. The distinctive double-peak feature seen in the majority of the volcanic signals from both poles at AD 676×2 and AD 688×2 suggests that these signals may belong to the same eruption, with those cores dating the signals to c.AD 676 generally considered to have a more precise chronology. Combining the evidence from natural and historical anthropogenic records and taking into account uncertainties (e.g. resolution, dating accuracy) associated with individual ice cores, we propose that a (most-likely) low-latitude eruption took place around AD676, followed by another possible eruption around AD700, identifiable by the significant acidity in polar ice-caps and historical documents. Unique historical observations of 'blood rain' in Ireland (often associated with Saharan sand deposition, but also plausibly with iron and manganese-rich tephra falls) also suggest a high-latitude eruption (possibly Icelandic) at AD693, corresponding to a

  19. Santa Maria Volcano, Guatemala

    Science.gov (United States)

    2002-01-01

    The eruption of Santa Maria volcano in 1902 was one of the largest eruptions of the 20th century, forming a large crater on the mountain's southwest flank. Since 1922, a lava-dome complex, Santiaguito, has been forming in the 1902 crater. Growth of the dome has produced pyroclastic flows as recently as the 2001-they can be identified in this image. The city of Quezaltenango (approximately 90,000 people in 1989) sits below the 3772 m summit. The volcano is considered dangerous because of the possibility of a dome collapse such as one that occurred in 1929, which killed about 5000 people. A second hazard results from the flow of volcanic debris into rivers south of Santiaguito, which can lead to catastrophic flooding and mud flows. More information on this volcano can be found at web sites maintained by the Smithsonian Institution, Volcano World, and Michigan Tech University. ISS004-ESC-7999 was taken 17 February 2002 from the International Space Station using a digital camera. The image is provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Searching and viewing of additional images taken by astronauts and cosmonauts is available at the NASA-JSC Gateway to

  20. Mount Rainier active cascade volcano

    Science.gov (United States)

    1994-01-01

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  1. Mount Rainier active cascade volcano

    Science.gov (United States)

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  2. Geothermal exploration results at the Ceboruco volcano, Nayarit State, Mexico; Resultados de la exploracion geotermica en el volcan Ceboruco en el estado de Nayarit, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Venegas S, Saul [Gerencia de Proyectos Geotermoelectricos de la Comision Federal de Electricidad, Morelia (Mexico)

    1995-05-01

    Since the seventies, in Mexico, the thermal areas census and the geothermal exploration have been carried out by the Geothermal Division of Comision Federal de Electricidad (CFE), including geological, geophysical and geochemical studies and deep exploratory wells, most of them located in the Mexican Volcanic Belt (MVB). In recent years, the exploration has been intensified in the northwestern sector of this regional structure, called the Tepic-Chapala graben, also named by some authors as the Zacoalco-Tepic graben. Due to the large volumes of plio-quaternary volcanism between the tectonic limits of the Sierra Madre Occidental (SMO) and the Jalisco Block (JB), one of the greatest geothermal interest areas is located between the large volcanic apparatus of Ceboruco, Domes of San Pedro, and Tepetiltic, in the State of Nayarit, where CFE has drilled 3 deep exploratory wells. The obtained results, demonstrate that the tectonic limit between SMO and BJ physiographic provinces is much more complex than initially proposed and the hypothetical Quaternary continental rift type structure, could be of Miocene age, because in the three wells discordant lithologic contact was observed between the BJ and the MVB. Also the measured thermal gradient in the Ceboruco No. 1 well (112 degrees celsius to 2800 m), does not correspond the typical heat flow of this type of recent structures. [Espanol] La Gerencia de Proyectos Geotermoelectricos, dependiente de la Comision Federal de Electricidad (CFE), ha realizado desde 1970, el censo de focos termales en el pais. La prospeccion geotermica con base en estudios de geologia, geofisica, geoquimica y construccion tanto de pozos exploratorios profundos como de desarrollo, define a la estructura del Eje Neovolcanico Mexicano (ENM), como la provincia fisiografica con mayores posibilidades para el desarrollo de la energia geotermica. En el sector noroccidental de esta estructura regional, en los limites tectonicos de la Sierra Madre Occidental

  3. Geology of Kilauea volcano

    Energy Technology Data Exchange (ETDEWEB)

    Moore, R.B. (Geological Survey, Denver, CO (United States). Federal Center); Trusdell, F.A. (Geological Survey, Hawaii National Park, HI (United States). Hawaiian Volcano Observatory)

    1993-08-01

    This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower east rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailed geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. 71 refs., 2 figs.

  4. 4D volcano gravimetry

    Science.gov (United States)

    Battaglia, Maurizio; Gottsmann, J.; Carbone, D.; Fernandez, J.

    2008-01-01

    Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast (hours to weeks), as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera (California, U.S.A.) and Campi Flegrei (Italy), careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological inter-pretations, particularly when the real crust surrounding the source is far from the homogeneous/ isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located (e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography). Applications at Teide volcano (Tenerife) and Campi Flegrei demonstrate the

  5. 五大连池老黑山、火烧山火山岩屑崩落堆积的发现及其喷发历史和模式的重塑%Discovery of Volcanic Debris-Avalanche Deposits in Laohei and Huoshao Volcanoes, Wudalianchi World Geopark, and Ascertaining the Volcanoes' History and Eruptive Model Again

    Institute of Scientific and Technical Information of China (English)

    刘祥; 郎建军

    2011-01-01

    large debris avalanche blocks should be the block facies of the debris avalanche deposits and the blocks consist of grey-purple basaltic volcanic agglomerate and volcanic breccia that as same as that of the rocks exposed in the base of the cones of Laohei Mountain and Huoshao Mountain, which indicate that these deposit resulted from the avalanche event happened in the two volcanoes. Most of the debris avalanche blocks were shattered strongly, but is partial preservation of primary edifice stratigraphy occasionally. These blocks were highly fractured and often with small fauts. During period of 1720 ~ 1721 AD the Laohei Mountain volcano formed in the Middle Pleistocene (0. 16Ma) and Huoshao Mountain volcano erupted again. The eruption model is: debris-avalanche ( debris-avalanche deposits and hummocky terrain ) -lava flows ( aa-lava and pahoehoe-lava)-Strombolian column (scoria cones of both Laohei Mountain and Huoshao Mountain and tepra sheets around the cones). Hazards derived from the avalanche themselves, as well as from associated pyroclastic flow and lahar that exceed damage beyond the debris avalanche deposits have been discussed.

  6. Vanishing Volcano

    Institute of Scientific and Technical Information of China (English)

    杨树仁

    1995-01-01

    Mauna Loa, the world’s largest active volcano,is sinking into the Pacific Ocean——and it’s taking the main island of Hawaii with it! The problem:The mighty volcano has gained too much weight, says Peter Lipman of the U. S. Geological Survey.

  7. Magma supply, storage, and transport at shield-stage Hawaiian volcanoes: Chapter 5 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Poland, Michael P.; Miklius, Asta; Montgomery-Brown, Emily K.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    The characteristics of magma supply, storage, and transport are among the most critical parameters governing volcanic activity, yet they remain largely unconstrained because all three processes are hidden beneath the surface. Hawaiian volcanoes, particularly Kīlauea and Mauna Loa, offer excellent prospects for studying subsurface magmatic processes, owing to their accessibility and frequent eruptive and intrusive activity. In addition, the Hawaiian Volcano Observatory, founded in 1912, maintains long records of geological, geophysical, and geochemical data. As a result, Hawaiian volcanoes have served as both a model for basaltic volcanism in general and a starting point for many studies of volcanic processes.

  8. Alberca De Guadalupe Maar Crater, Zacapu Basin : A Rare Type of Volcano within the Michoacán-Guanajuato Volcanic Field, México

    Science.gov (United States)

    Kshirsagar, P. V.; Siebe, C.; Guilbaud, M. N.; Salinas, S.

    2014-12-01

    Phreato-magmatic vents (esp. maar craters) are rare in the ~40,000 Km2 Plio-Quaternary monogenetic Michoacán-Guanajuato Volcanic Field (MGVF) located in the central part of the Mexican Volcanic Belt. In contrast to >1000 scoria cones, only 2 dozen phreato-magmatic monogenetic vents (e.g. tuff cones, tuff rings, and maars) have been identified. About half of these form a cluster near Valle de Santiago in the Lerma river valley at the northern margin of the MGVF, while the others occur in a rather scattered fashion. Here we discuss the origin of Alberca de Guadalupe maar crater, one of the three phreato-magmatic vents (in addition to El Caracol and Alberca de Los Espinos) that occur within the boundaries of the inter-montane lacustrine Zacapu basin, a tectonic graben bound by an ENE-WSW normal fault system. The maar crater came into existence between 20,000 and 23,000 y BP, forming a 140 m deep hole in the otherwise planar surrounding ground of theearly Pleistocene lava flows of Cerro Pelón.The maar crater has a diameter of ~1 Km and bears a 9 m deep lake. Eruptive products include typical surge deposits that are best exposed around the rim and inner crater walls. They are poorly sorted (Mdø= -1.56 to -3.75, ø= 1.43 to 3.23), rich in accidental lithics (angular andesitic lava and ignimbrite clasts) constituting 51-88% of the deposit with few juveniles (basaltic andesite with phenocrysts of plagioclase, olivine, and pyroxene in a quenched glassy matrix; SiO2=54-58 wt. %). Dry surge units are friable and clast-supported, in contrast the wet surge units are fairly indurated and bear accretionary lapilli. Bedding is frequently distorted by ballistic impact-sag structures. The entire construct is disrupted by an E-W trending regional fault, downthrowing the northern part by ~30 m.The unusual formation of this maar crater in the semi-arid highlands of Zacapu was favored by the local hydrological and topographical conditions. Such conditions still prevail in several

  9. Cyclists' attitudes toward policies encouraging bicycle travel: findings from the Taupo Bicycle Study in New Zealand.

    Science.gov (United States)

    Tin Tin, Sandar; Woodward, Alistair; Thornley, Simon; Langley, John; Rodgers, Anthony; Ameratunga, Shanthi

    2010-03-01

    Utility cycling provides substantial health, environmental and economic benefits. Despite a favourable trend in leisure-time cycling, cycling is infrequently used for everyday travel needs in New Zealand. This study investigated cyclists' attitudes toward environmental and policy measures that would encourage them to cycle more, particularly for a trip to work. A cross-sectional analysis was undertaken using baseline data obtained from the Taupo Bicycle Study, a web-based longitudinal study. The study population comprised 2469 cyclists, aged 16 years or over, who had enrolled in the 2006 Wattyl Lake Taupo Cycle Challenge. The majority (88%) reported the provision of bicycle lanes as an important factor that would encourage them to cycle more often, followed by bicycle paths (76%), better bicycle security (64%), reduced motor vehicle speed (55%) and bike friendly public transport (38%). Of those who reported travelling to work at least once a week (N = 2223), varying proportions reported shower facilities at work (61%), fewer difficult intersections (43%), rising fuel costs (41%), fewer car parks (27%), bike designed to commute (26%) and rising cost of car parking (25%) as important factors that would encourage them to cycle to work more often. There were important differences in these perceived influences defined by the participants' socio-demographic characteristics and current cycling habits.

  10. Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Founded in 1912 at the edge of the caldera of Kīlauea Volcano, HVO was the vision of Thomas A. Jaggar, Jr., a geologist from the Massachusetts Institute of Technology, whose studies of natural disasters around the world had convinced him that systematic, continuous observations of seismic and volcanic activity were needed to better understand—and potentially predict—earthquakes and volcanic eruptions. Jaggar summarized the aim of HVO by stating that “the work should be humanitarian” and have the goals of developing “prediction and methods of protecting life and property on the basis of sound scientific achievement.” These goals align well with those of the USGS, whose mission is to serve the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage natural resources; and enhance and protect our quality of life.

  11. A high-resolution 40Ar/39Ar lava chronology and edifice construction history for Ruapehu volcano, New Zealand

    Science.gov (United States)

    Conway, Chris E.; Leonard, Graham S.; Townsend, Dougal B.; Calvert, Andrew T.; Wilson, Colin J. N.; Gamble, John A.; Eaves, Shaun R.

    2016-11-01

    Ruapehu is an active 150 km3 andesite-dacite composite volcano located at the southern end of the Taupo Volcanic Zone, New Zealand. The growth of the present-day edifice has occurred throughout coeval eruptive and glacial histories since 200 ka. We present high-precision 40Ar/39Ar eruption ages for 46 samples and whole-rock major element geochemical data for 238 samples from lava flows. These new and existing data are interpreted in the context of geomorphologic and geologic mapping, volcano-ice interaction processes and glacier reconstructions to present an improved chronostratigraphic framework and new edifice evolution history for Ruapehu. Sub-glacial to ice-marginal effusive eruption of medium-K basaltic-andesites and andesites constructed the northern portion of the exposed edifice between 200 and 150 ka, and a wide southeast planèze as well as parts of the northern, eastern and western flanks between 160 and 80 ka. None of the dated lava flows have ages in the range of 80-50 ka, which may reflect an eruptive hiatus. Alternatively the lack of ages may be the result of erosion and burial of lavas and syn-eruptive glacial conveyance of lava flows to the ring-plain during glacial advance at 70-60 ka. From 50-15 ka edifice growth occurred via effusive eruptions onto the glaciated flanks of the volcano, resulting in construction of ice-bounded planèzes and ridges. The distribution of dated ice-marginal lavas indicates a general decrease in glacier thicknesses over this time, except for a short-lived period centred at 31 ka when peak ice cover was reached. The compositional ranges of medium- to high-K andesite and dacite lava flows within 50-35 ka eruptive packages define broadly bimodal high- and low-MgO trends. Lavas erupted at 35-22 ka have compositions that fill a transitional geochemical field between older dacites and younger andesites. Large-scale retreat of flank glaciers since 15 ka has resulted in intra-valley lava flow emplacement at elevations below

  12. High-K andesite petrogenesis and crustal evolution: Evidence from mafic and ultramafic xenoliths, Egmont Volcano (Mt. Taranaki) and comparisons with Ruapehu Volcano, North Island, New Zealand

    Science.gov (United States)

    Price, Richard C.; Smith, Ian E. M.; Stewart, Robert B.; Gamble, John A.; Gruender, Kerstin; Maas, Roland

    2016-07-01

    This study uses the geochemistry and petrology of xenoliths to constrain the evolutionary pathways of host magmas at two adjacent andesitic volcanoes in New Zealand's North Island. Egmont (Mt. Taranaki) is located on the west coast of the North Island and Ruapehu lies 140 km to the east at the southern end of the Taupo Volcanic Zone, the principal locus of subduction-related magmatism in New Zealand. Xenoliths are common in the eruptives of both volcanoes but the xenoliths suites are petrographically and geochemically different. Ruapehu xenoliths are predominantly pyroxene-plagioclase granulites derived from Mesozoic meta-greywacke basement and the underlying oceanic crust. The xenolith population of Egmont Volcano is more complex. It includes sedimentary, metamorphic and plutonic rocks from the underlying basement but is dominated by coarse grained, mafic and ultramafic igneous rocks. Gabbroic xenoliths (Group 1) are composed of plagioclase, clinopyroxene and amphibole whereas ultramafic xenoliths are dominated by amphibole (Group 2) or pyroxene (Group 3) or, in very rare cases, olivine (Group 4). In Group 1 xenoliths plagioclase and clinopyroxene and in some cases amphibole show cumulate textures. Amphibole also occurs as intercumulate poikilitic crystals or as blebs or laminae replacing pyroxene. Some Group 2 xenoliths have cumulate textures but near monomineralic amphibole xenoliths are coarse grained with bladed or comb textures. Pyroxene in Group 3 xenoliths has a polygonal granoblastic texture that is commonly overprinted by veining and amphibole replacement. Group 1 and most Group 2 xenoliths have major, trace element and Sr, Nd and Pb isotope compositions indicating affinity with the host volcanic rocks. Geochemical variation can be modelled by assimilation fractional crystallisation (AFC) and fractional crystallisation (FC) of basaltic parents assuming an assimilant with the composition of average crystalline basement and Group 1 xenoliths have

  13. Global Volcano Model

    Science.gov (United States)

    Sparks, R. S. J.; Loughlin, S. C.; Cottrell, E.; Valentine, G.; Newhall, C.; Jolly, G.; Papale, P.; Takarada, S.; Crosweller, S.; Nayembil, M.; Arora, B.; Lowndes, J.; Connor, C.; Eichelberger, J.; Nadim, F.; Smolka, A.; Michel, G.; Muir-Wood, R.; Horwell, C.

    2012-04-01

    Over 600 million people live close enough to active volcanoes to be affected when they erupt. Volcanic eruptions cause loss of life, significant economic losses and severe disruption to people's lives, as highlighted by the recent eruption of Mount Merapi in Indonesia. The eruption of Eyjafjallajökull, Iceland in 2010 illustrated the potential of even small eruptions to have major impact on the modern world through disruption of complex critical infrastructure and business. The effects in the developing world on economic growth and development can be severe. There is evidence that large eruptions can cause a change in the earth's climate for several years afterwards. Aside from meteor impact and possibly an extreme solar event, very large magnitude explosive volcanic eruptions may be the only natural hazard that could cause a global catastrophe. GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. We are designing and developing an integrated database system of volcanic hazards, vulnerability and exposure with internationally agreed metadata standards. GVM will establish methodologies for analysis of the data (eg vulnerability indices) to inform risk assessment, develop complementary hazards models and create relevant hazards and risk assessment tools. GVM will develop the capability to anticipate future volcanism and its consequences. NERC is funding the start-up of this initiative for three years from November 2011. GVM builds directly on the VOGRIPA project started as part of the GRIP (Global Risk Identification Programme) in 2004 under the auspices of the World Bank and UN. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM.

  14. Common processes at unique volcanoes – a volcanological conundrum

    Directory of Open Access Journals (Sweden)

    Katharine eCashman

    2014-11-01

    Full Text Available An emerging challenge in modern volcanology is the apparent contradiction between the perception that every volcano is unique, and classification systems based on commonalities among volcano morphology and eruptive style. On the one hand, detailed studies of individual volcanoes show that a single volcano often exhibits similar patterns of behaviour over multiple eruptive episodes; this observation has led to the idea that each volcano has its own distinctive pattern of behaviour (or personality. In contrast, volcano classification schemes define eruption styles referenced to type volcanoes (e.g. Plinian, Strombolian, Vulcanian; this approach implicitly assumes that common processes underpin volcanic activity and can be used to predict the nature, extent and ensuing hazards of individual volcanoes. Actual volcanic eruptions, however, often include multiple styles, and type volcanoes may experience atypical eruptions (e.g., violent explosive eruptions of Kilauea, Hawaii1. The volcanological community is thus left with a fundamental conundrum that pits the uniqueness of individual volcanic systems against generalization of common processes. Addressing this challenge represents a major challenge to volcano research.

  15. Lahar-hazard zonation for San Miguel volcano, El Salvador

    Science.gov (United States)

    Major, J.J.; Schilling, S.P.; Pullinger, C.R.; Escobar, C.D.; Chesner, C.A.; Howell, M.M.

    2001-01-01

    San Miguel volcano, also known as Chaparrastique, is one of many volcanoes along the volcanic arc in El Salvador. The volcano, located in the eastern part of the country, rises to an altitude of about 2130 meters and towers above the communities of San Miguel, El Transito, San Rafael Oriente, and San Jorge. In addition to the larger communities that surround the volcano, several smaller communities and coffee plantations are located on or around the flanks of the volcano, and the PanAmerican and coastal highways cross the lowermost northern and southern flanks of the volcano. The population density around San Miguel volcano coupled with the proximity of major transportation routes increases the risk that even small volcano-related events, like landslides or eruptions, may have significant impact on people and infrastructure. San Miguel volcano is one of the most active volcanoes in El Salvador; it has erupted at least 29 times since 1699. Historical eruptions of the volcano consisted mainly of relatively quiescent emplacement of lava flows or minor explosions that generated modest tephra falls (erupted fragments of microscopic ash to meter sized blocks that are dispersed into the atmosphere and fall to the ground). Little is known, however, about prehistoric eruptions of the volcano. Chemical analyses of prehistoric lava flows and thin tephra falls from San Miguel volcano indicate that the volcano is composed dominantly of basalt (rock having silica content

  16. Triggering of volcanic eruptions by large earthquakes

    Science.gov (United States)

    Nishimura, Takeshi

    2017-08-01

    When a large earthquake occurs near an active volcano, there is often concern that volcanic eruptions may be triggered by the earthquake. In this study, recently accumulated, reliable data were analyzed to quantitatively evaluate the probability of the occurrence of new eruptions of volcanoes located near the epicenters of large earthquakes. For volcanoes located within 200 km of large earthquakes of magnitude 7.5 or greater, the eruption occurrence probability increases by approximately 50% for 5 years after the earthquake origin time. However, no significant increase in the occurrence probability of new eruptions was observed at distant volcanoes or for smaller earthquakes. The present results strongly suggest that new eruptions are likely triggered by static stress changes and/or strong ground motions caused by nearby large earthquakes. This is not similar to the previously presented evidence that volcanic earthquakes at distant volcanoes are remotely triggered by surface waves generated by large earthquakes.

  17. Revealing magma degassing below closed-conduit active volcanoes: Geochemical features of volcanic rocks versus fumarolic fluids at Vulcano (Aeolian Islands, Italy)

    Science.gov (United States)

    Mandarano, Michela; Paonita, Antonio; Martelli, Mauro; Viccaro, Marco; Nicotra, Eugenio; Millar, Ian L.

    2016-04-01

    The elemental and isotopic compositions of noble gases (He, Ne, and Ar) in olivine- and clinopyroxene-hosted fluid inclusions have been measured for rocks at various degrees of evolution and belonging to high-K calcalkaline-shoshonitic and shoshonitic-potassic series in order to cover the entire volcanological history of Vulcano Island (Italy). The major- and trace-element concentrations and the Sr- and Pb-isotope compositions for whole rocks were integrated with data obtained from the fluid inclusions. 3He/4He in fluid inclusions is within the range of 3.30 and 5.94 R/Ra, being lower than the theoretical value for the deep magmatic source expected for Vulcano Island (6.0-6.2 R/Ra). 3He/4He of the magmatic source is almost constant throughout the volcanic history of Vulcano. Integration of the He- and Sr-isotope systematics leads to the conclusion that a decrease in the He-isotope ratio of the rocks is mainly due to the assimilation of 10-25% of a crustal component similar to the Calabrian basement. 3He/4He shows a negative correlation with Sr isotopes except for the last-erupted Vulcanello latites (Punta del Roveto), which have anomalously high He isotope ratios. This anomaly has been attributed to a flushing process by fluids coming from the deepest reservoirs, since an input of deep magmatic volatiles with high 3He/4He values increases the He-isotope ratio without changing 87Sr/86Sr. A comparison of the He-isotope ratios between fluid inclusions and fumarolic gases shows that only the basalts of La Sommata and the latites of Vulcanello have comparable values. Taking into account that the latites of Vulcanello relate to one of the most-recent eruptions at Vulcano (in the 17th century), we infer that the most probable magma which actually feeds the fumarolic emissions is a latitic body that ponded at about 3-3.5 km of depth and is flushed by fluids coming from a deeper and basic magma.

  18. Revealing the magmas degassing below closed-conduit active volcanoes: noble gases in volcanic rocks versus fumarolic fluids at Vulcano (Aeolian Islands, Italy)

    Science.gov (United States)

    Mandarano, Michela; Paonita, Antonio; Martelli, Mauro; Viccaro, Marco; Nicotra, Eugenio; Millar, Ian L.

    2016-04-01

    With the aim to constrain the nature of magma currently feeding the fumarolic field of Vulcano, we measured the elemental and isotopic compositions of noble gases (He, Ne, and Ar) in olivine- and clinopyroxene-hosted fluid inclusions in high-K calcalcaline-shoshonitic and shoshonitic-potassic series so as to cover the entire volcanological history of Vulcano Island (Italy). The major and trace-element concentrations and the Sr- and Pb-isotope compositions for whole rocks were integrated with data obtained from the fluid inclusions. 3He/4He in fluid inclusions is within the range of 3.30 and 5.94 R/Ra, being lower than the value for the deep magmatic source expected for Vulcano Island (6.0-6.2 R/Ra). 3He/4He of the magmatic source is almost constant throughout the volcanic record of Vulcano. Integration of the He- and Sr-isotope systematics leads to the conclusion that a decrease in the He-isotope ratio of the rocks is mainly due to the assimilation of 10-25% of a crustal component similar to the Calabrian basement. 3He/4He shows a negative correlation with Sr isotopes except for the last-emitted Vulcanello latites (Punta del Roveto), which have high He- and Sr-isotope ratios. This anomaly has been attributed to a flushing process by fluids coming from the deepest reservoirs. Indeed, an input of deep magmatic volatiles with high 3He/4He values increases the He-isotope ratio without changing 87Sr/86Sr. A comparison of the He isotope ratios between fluid inclusions and fumarolic gases showed that only the basalts of La Sommata and the latites of Vulcanello have comparable values. Taking into account that the latites of Vulcanello relate to one of the most-recent eruptions at Vulcano (in the 17th century), we infer that that the most probable magma which actually feeds the fumarolic emissions is a latitic body ponding at about 3-3.5 km of depth and flushed by fluids coming from a deeper and basic magma.

  19. Dante's volcano

    Science.gov (United States)

    1994-09-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  20. Preliminary volcano-hazard assessment for Augustine Volcano, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Waitt, Richard B.

    1998-01-01

    Augustine Volcano is a 1250-meter high stratovolcano in southwestern Cook Inlet about 280 kilometers southwest of Anchorage and within about 300 kilometers of more than half of the population of Alaska. Explosive eruptions have occurred six times since the early 1800s (1812, 1883, 1935, 1964-65, 1976, and 1986). The 1976 and 1986 eruptions began with an initial series of vent-clearing explosions and high vertical plumes of volcanic ash followed by pyroclastic flows, surges, and lahars on the volcano flanks. Unlike some prehistoric eruptions, a summit edifice collapse and debris avalanche did not occur in 1812, 1935, 1964-65, 1976, or 1986. However, early in the 1883 eruption, a portion of the volcano summit broke loose forming a debris avalanche that flowed to the sea. The avalanche initiated a small tsunami reported on the Kenai Peninsula at English Bay, 90 kilometers east of the volcano. Plumes of volcanic ash are a major hazard to jet aircraft using Anchorage International and other local airports. Ashfall from future eruptions could disrupt oil and gas operations and shipping activities in Cook Inlet. Eruptions similar to the historical and prehistoric eruptions are likely in Augustine's future.

  1. What Are Volcano Hazards?

    Science.gov (United States)

    ... Sheet 002-97 Revised March 2008 What Are Volcano Hazards? Volcanoes give rise to numerous geologic and ... as far as 15 miles from the volcano. Volcano Landslides A landslide or debris avalanche is a ...

  2. Tectonostratigraphy and depositional history of the Neoproterozoic volcano-sedimentary sequences in Kid area, southeastern Sinai, Egypt: Implications for intra-arc to foreland basin in the northern Arabian-Nubian Shield

    Science.gov (United States)

    Khalaf, E. A.; Obeid, M. A.

    2013-09-01

    This paper presents a stratigraphic and sedimentary study of Neoproterozoic successions of the South Sinai, at the northernmost segment of the Arabian-Nubian Shield (ANS), including the Kid complex. This complex is composed predominantly of thick volcano-sedimentary successions representing different depositional and tectonic environments, followed by four deformational phases including folding and brittle faults (D1-D4). The whole Kid area is divisible from north to south into the lower, middle, and upper rock sequences. The higher metamorphic grade and extensive deformational styles of the lower sequence distinguishes them from the middle and upper sequences. Principal lithofacies in the lower sequence include thrust-imbricated tectonic slice of metasediments and metavolcanics, whereas the middle and upper sequences are made up of clastic sediments, intermediate-felsic lavas, volcaniclastics, and dike swarms. Two distinct Paleo- depositional environments are observed: deep-marine and alluvial fan regime. The former occurred mainly during the lower sequence, whereas the latter developed during the other two sequences. These alternations of depositional conditions in the volcano-sedimentary deposits suggest that the Kid area may have formed under a transitional climate regime fluctuating gradually from warm and dry to warm and humid conditions. Geochemical and petrographical data, in conjunction with field relationships, suggest that the investigated volcano-sedimentary rocks were built from detritus derived from a wide range of sources, ranging from Paleoproterozoic to Neoproterozoic continental crust. Deposition within the ancient Kid basin reflects a complete basin cycle from rifting and passive margin development, to intra-arc and foreland basin development and, finally, basin closure. The early phase of basin evolution is similar to various basins in the Taupo volcanics, whereas the later phases are similar to the Cordilleran-type foreland basin. The

  3. Volcano ecology: Disturbance characteristics and assembly of biological communities

    Science.gov (United States)

    Volcanic eruptions are powerful expressions of Earth’s geophysical forces which have shaped and influenced ecological systems since the earliest days of life. The study of the interactions of volcanoes and ecosystems, termed volcano ecology, focuses on the ecological responses of organisms and biolo...

  4. The significance of SAR remote sensing in volcano-geology for hazard and resource potential mapping

    Science.gov (United States)

    Saepuloh, Asep; Bakker, Erwin; Suminar, Wulan

    2017-07-01

    Geological mapping at volcanic terrain is crucial for providing accurate information related to the distribution of volcanic products and volcano-related structures. The volcano-geology map is basis information, not only for hazard mitigation related to volcanic activity, but also for resource exploration as well as scientific purposes. Therefore, the accurate detection and observation of volcanic products and their genetics are necessary for volcano-geology mapping. The classical problem at Torrid Zone such as cloud, dense vegetation, heavy weathering, and erosion usually hamper the detection and observation of volcanic products and their structures. Moreover, the stratigraphic of volcanic products generally follows paleo-topography which was buried by the products. Overcoming the problem, we exploited the applicability of remotely sensed data to provide the great assistance for field based observations at volcanic field in Indonesia. The Geomorphologic and Structural Features (GSF) of the Synthetic Aperture Radar (SAR) are the selected parameters to define the distribution of the volcanic products. We explained about the significant of SAR identification to detect and interpret volcano-geology parameters such as eruption centers, volcanic products, depositional mechanisms, and volcanic structures especially at complex of volcanoes. The fall and flowing mechanisms controlled the depositional process were also analyzed to obtain the genetic of volcanic products. For young volcanoes, the quantitative techniques based on SAR surface roughness and polarized signatures are effective to identify volcanic formations and their sources. However, for old volcanoes the visual analyses of GSF is superior to identify the volcanic units and structures. We selected two volcanic complexes at Mts. Guntur and Malabar in West Java (Indonesia) presenting the young and old volcanic field characteristics under Torrid Zone condition.

  5. The Online GVP/USGS Weekly Volcanic Activity Report: Providing Timely Information About Worldwide Volcanism

    Science.gov (United States)

    Mayberry, G. C.; Guffanti, M. C.; Luhr, J. F.; Venzke, E. A.; Wunderman, R. L.

    2001-12-01

    The awesome power and intricate inner workings of volcanoes have made them a popular subject with scientists and the general public alike. About 1500 known volcanoes have been active on Earth during the Holocene, approximately 50 of which erupt per year. With so much activity occurring around the world, often in remote locations, it can be difficult to find up-to-date information about current volcanism from a reliable source. To satisfy the desire for timely volcano-related information the Smithsonian Institution and US Geological Survey combined their strengths to create the Weekly Volcanic Activity Report. The Smithsonian's Global Volcanism Program (GVP) has developed a network of correspondents while reporting worldwide volcanism for over 30 years in their monthly Bulletin of the Global Volcanism Network. The US Geological Survey's Volcano Hazards Program studies and monitors volcanoes in the United States and responds (upon invitation) to selected volcanic crises in other countries. The Weekly Volcanic Activity Report is one of the most popular sites on both organization's websites. The core of the Weekly Volcanic Activity Report is the brief summaries of current volcanic activity around the world. In addition to discussing various types of volcanism, the summaries also describe precursory activity (e.g. volcanic seismicity, deformation, and gas emissions), secondary activity (e.g. debris flows, mass wasting, and rockfalls), volcanic ash hazards to aviation, and preventative measures. The summaries are supplemented by links to definitions of technical terms found in the USGS photoglossary of volcano terms, links to information sources, and background information about reported volcanoes. The site also includes maps that highlight the location of reported volcanoes, an archive of weekly reports sorted by volcano and date, and links to commonly used acronyms. Since the Weekly Volcanic Activity Report's inception in November 2000, activity has been reported at

  6. Investigation of a fossil geothermal system, Hamblin-Cleopatra Volcano, Clark County, Nevada. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Barker, D.S.

    1986-07-28

    The Hamblin-Cleopatra volcano, selected for study because erosion and fault displacement have exposed the entire volcanic succession, the intrusive core, a radial dike systems, and sedimentary and volcanic rocks that predate and postdate the volcano, was investigated to estimate the proportions of igneous materials forming lava flows, pyroclastic deposits, intrusive bodies, and reworked debris. Chemical changes in the magma throughout the active period of the volcano were documented. The geothermal system active within the pile after activity ceased was reconstructed. (ACR)

  7. Monogenetic volcanism: personal views and discussion

    Science.gov (United States)

    Németh, K.; Kereszturi, G.

    2015-11-01

    Monogenetic volcanism produces small-volume volcanoes with a wide range of eruptive styles, lithological features and geomorphic architectures. They are classified as spatter cones, scoria (or cinder) cones, tuff rings, maars (maar-diatremes) and tuff cones based on the magma/water ratio, dominant eruption styles and their typical surface morphotypes. The common interplay between internal, such as the physical-chemical characteristics of magma, and external parameters, such as groundwater flow, substrate characteristics or topography, plays an important role in creating small-volume volcanoes with diverse architectures, which can give the impression of complexity and of similarities to large-volume polygenetic volcanoes. In spite of this volcanic facies complexity, we defend the term "monogenetic volcano" and highlight the term's value, especially to express volcano morphotypes. This study defines a monogenetic volcano, a volcanic edifice with a small cumulative volume (typically ≤1 km3) that has been built up by one continuous, or many discontinuous, small eruptions fed from one or multiple magma batches. This definition provides a reasonable explanation of the recently recognized chemical diversities of this type of volcanism.

  8. Evolution of {sup 222} Rn and chemical species related with eruptive processes of the Popocatepetl volcano; Evolucion de {sup 222} Rn y especies quimicas relacionadas con procesos eruptivos del volcan Popocatepetl

    Energy Technology Data Exchange (ETDEWEB)

    Aranda Z, P

    1998-10-01

    The study of the water quality for human consumption has always been great importance, considering the factors that can affect water quality as aquifers recharge and underground permeability. In this work, the behavior of three water springs related with the Popocatepetl volcano were studied within April 1997 and March 1998. The spring in Paso de Cortes in the municipality of Amecameca, State of Mexico, and the springs of Atlimeyaya and Axocopan in Atlixco, State of Puebla; the water of these last two springs is used for human consumption. The content of radon in water was determined by means of liquid scintillation, and a concentration of 1.22 Bq/l was found in the spring of Atlimeyaya, which represents 2 % of the maximum permissible level established by ICRP. A significant increase was observed in the Paso de Cortes spring in the month of July 1997. The content of radium, was determined by means of gamma spectrophotometry and small quantities of this element (<0.11 Bq/l) were found. Water chemical analysis also included usual physical-chemical parameters determination by means of conventional methods. The spring of Axocopan, was found to have the major level of minerals, followed by Atlimeyaya and finally the Paso de Cortes spring, which is supplied by recent infiltrated water. Fluoride level showed a peak high level in concentration during the months of October and November, time in which infiltration due to rain is low; concentration level found was above the maximum permissible level established by Mexican authorities for this compound. The other chemical species determined were: Ca{sup 2+} , Mg{sup 2+} , K{sup +}, Na{sup +}, H C O{sub 3} {sup -} , Cl{sup -} , S O{sub 4} {sup -} {sup 2} , Li, B, Sc, Ti, V, Rb, Sr and Ba, primarily, which did not show any significant variation with the change of seasons. No important variations in the concentration of radon, radium or for other volcanic activity related species were found in the entire study. (Author)

  9. Instrumentation Recommendations for Volcano Monitoring at U.S. Volcanoes Under the National Volcano Early Warning System

    Science.gov (United States)

    Moran, Seth C.; Freymueller, Jeff T.; LaHusen, Richard G.; McGee, Kenneth A.; Poland, Michael P.; Power, John A.; Schmidt, David A.; Schneider, David J.; Stephens, George; Werner, Cynthia A.; White, Randall A.

    2008-01-01

    As magma moves toward the surface, it interacts with anything in its path: hydrothermal systems, cooling magma bodies from previous eruptions, and (or) the surrounding 'country rock'. Magma also undergoes significant changes in its physical properties as pressure and temperature conditions change along its path. These interactions and changes lead to a range of geophysical and geochemical phenomena. The goal of volcano monitoring is to detect and correctly interpret such phenomena in order to provide early and accurate warnings of impending eruptions. Given the well-documented hazards posed by volcanoes to both ground-based populations (for example, Blong, 1984; Scott, 1989) and aviation (for example, Neal and others, 1997; Miller and Casadevall, 2000), volcano monitoring is critical for public safety and hazard mitigation. Only with adequate monitoring systems in place can volcano observatories provide accurate and timely forecasts and alerts of possible eruptive activity. At most U.S. volcanoes, observatories traditionally have employed a two-component approach to volcano monitoring: (1) install instrumentation sufficient to detect unrest at volcanic systems likely to erupt in the not-too-distant future; and (2) once unrest is detected, install any instrumentation needed for eruption prediction and monitoring. This reactive approach is problematic, however, for two reasons. 1. At many volcanoes, rapid installation of new ground-1. based instruments is difficult or impossible. Factors that complicate rapid response include (a) eruptions that are preceded by short (hours to days) precursory sequences of geophysical and (or) geochemical activity, as occurred at Mount Redoubt (Alaska) in 1989 (24 hours), Anatahan (Mariana Islands) in 2003 (6 hours), and Mount St. Helens (Washington) in 1980 and 2004 (7 and 8 days, respectively); (b) inclement weather conditions, which may prohibit installation of new equipment for days, weeks, or even months, particularly at

  10. Volcano hazards at Fuego and Acatenango, Guatemala

    Science.gov (United States)

    Vallance, J.W.; Schilling, S.P.; Matías, O.; Rose, William I.; Howell, M.M.

    2001-01-01

    The Fuego-Acatenango massif comprises a string of five or more volcanic vents along a north-south trend that is perpendicular to that of the Central American arc in Guatemala. From north to south known centers of volcanism are Ancient Acatenango, Yepocapa, Pico Mayor de Acatenango, Meseta, and Fuego. Volcanism along the trend stretches back more than 200,000 years. Although many of the centers have been active contemporaneously, there is a general sequence of younger volcanism, from north to south along the trend. This massive volcano complex towers more than 3500 meters (m) above the Pacific coastal plain to the south and 2000 m above the Guatemalan Highlands to the north. The volcano complex comprises remnants of multiple eruptive centers, which periodically have collapsed to form huge debris avalanches. The largest of these avalanches extended more than 50 kilometers (km) from its source and covered more than 300 square km. The volcano has potential to produce huge debris avalanches that could inundate large areas of the Pacific coastal plain. In areas around the volcanoes and downslope toward the coastal plain, more than 100,000 people are potentially at risk from these and other flowage phenomena.

  11. New volcanoes discovered in southeast Australia

    Science.gov (United States)

    Wendel, JoAnna

    2014-07-01

    Scientists have discovered three new active volcanoes in the Newer Volcanics Province (NVP) in southeast Australia. Researchers from Monash University in Melbourne describe in the Australian Journal of Earth Sciences how they used a combination of satellite photographs, detailed topography models from NASA, the distribution of magnetic minerals in the rocks, and site visits to analyze the region.

  12. Analysis of Distribution of Volcanoes around the Korean Peninsula and the Potential Effects on Korea

    Science.gov (United States)

    Choi, Eun-kyeong; Kim, Sung-wook

    2017-04-01

    Since the scale and disaster characteristics of volcanic eruptions are determined by their geological features, it is important not only to grasp the current states of the volcanoes in neighboring countries around the Korean Peninsula, but also to analyze the tectonic settings, tectonic regions, geological features, volcanic types, and eruption histories of these volcanoes. Volcanic data were based on the volcano information registered with the Global Volcanism Program at the Smithsonian Institute. We created a database of 289 volcanoes around Korea, Japan, China, Taiwan, and the Kamchatka area in Russia, and then identified a high-risk group of 29 volcanoes that are highly likely to affect the region, based on conditions such as volcanic activity, types of rock at risk of eruption, distance from Seoul, and volcanoes having Plinian eruption history with volcanic explosivity index (VEI) of 4 or more. We selected 29 hazardous volcanoes, including Baekdusan, Ulleungdo, and 27 Japanese volcanoes that can cause widespread ashfall on the Korean peninsula by potentially explosive eruptions. In addition, we identified ten volcanoes that should be given the highest priority, through an analysis of data available in literature, such as volcanic ash dispersion results from previous Japanese eruptions, the definition of a large-scale volcano used by Japan's Cabinet Office, and examination of cumulative magma layer volumes from Japan's quaternary volcanoes. We expect that predicting the extent of the spread of ash caused by this hazardous activity and analyzing its impact on the Korean peninsula will be help to predict volcanic ash damage as well as provide direction for hazard mitigation research. Acknowledgements This research was supported by a grant [MPSS-NH-2015-81] through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government.

  13. Single-station monitoring of volcanoes using seismic ambient noise

    Science.gov (United States)

    De Plaen, Raphael S. M.; Lecocq, Thomas; Caudron, Corentin; Ferrazzini, Valérie; Francis, Olivier

    2016-08-01

    Seismic ambient noise cross correlation is increasingly used to monitor volcanic activity. However, this method is usually limited to volcanoes equipped with large and dense networks of broadband stations. The single-station approach may provide a powerful and reliable alternative to the classical "cross-station" approach when measuring variation of seismic velocities. We implemented it on the Piton de la Fournaise in Reunion Island, a very active volcano with a remarkable multidisciplinary continuous monitoring. Over the past decade, this volcano has been increasingly studied using the traditional cross-correlation technique and therefore represents a unique laboratory to validate our approach. Our results, tested on stations located up to 3.5 km from the eruptive site, performed as well as the classical approach to detect the volcanic eruption in the 1-2 Hz frequency band. This opens new perspectives to successfully forecast volcanic activity at volcanoes equipped with a single three-component seismometer.

  14. Distribution of acidic groundwater around quaternary volcanoes in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Asamori, Koichi; Ishimaru, Tsuneari; Iwatsuki, Teruki [Japan Nuclear Cycle Development Inst., Toki, Gifu (Japan). Tono Geoscience Center

    2002-06-01

    One important key issue in the understanding of the long-term stability of the geological environment is the influence of magmatism. In this study, we examined the general spatial distribution of acidic groundwater around Quaternary volcanoes in Japan using a database of groundwater geochemistry. The results may be summarized as follows: Acidic groundwater with pH < 4.8 mainly occur in present volcanic regions and are distributed from several kilometers to about 20 km from Quaternary volcanoes. The pH value of groundwater tends to decrease with increasing distance from a volcano. However, these results may be affected by inhomogeneity of groundwater data distribution and the characteristic activity of each volcano. In order to assess a specific volcanic region, a detailed analysis that considers volcanic activity, using a data set with high spatial density is necessary. (author)

  15. Learning to recognize volcanic non-eruptions

    Science.gov (United States)

    Poland, Michael P.

    2010-01-01

    An important goal of volcanology is to answer the questions of when, where, and how a volcano will erupt—in other words, eruption prediction. Generally, eruption predictions are based on insights from monitoring data combined with the history of the volcano. An outstanding example is the A.D. 1980–1986 lava dome growth at Mount St. Helens, Washington (United States). Recognition of a consistent pattern of precursors revealed by geophysical, geological, and geochemical monitoring enabled successful predictions of more than 12 dome-building episodes (Swanson et al., 1983). At volcanic systems that are more complex or poorly understood, probabilistic forecasts can be useful (e.g., Newhall and Hoblitt, 2002; Marzocchi and Woo, 2009). In such cases, the probabilities of different types of volcanic events are quantified, using historical accounts and geological studies of a volcano's past activity, supplemented by information from similar volcanoes elsewhere, combined with contemporary monitoring information.

  16. Volcanic stratigraphy and evidence of magma mixing in the Quaternary Payún Matrú volcano, andean backarc in western Argentina Estratigrafía volcánica y evidencia de mezcla de magmas en el volcán Payún Matrú del Cuaternario, en el retroarco andino de Argentina occidental

    Directory of Open Access Journals (Sweden)

    Irene R Hernando

    2012-01-01

    Full Text Available The Payún Matrú Volcanic Field is located in the Payenia Basaltic Province of the recent back-arc of western Argentina (35°S-38°S. This province is younger than 5 Ma, and most of its volcanic activity took place since 2 Ma. The Payún Matrú Volcanic Field contains two composite volcanoes, Payún Matrú and Payún Liso, and two basaltic fields in an E-W oriented zone, located east and west of the Payún Matrú volcano. Payún Matrú is the largest volcano of this volcanic field, and consists of a shield-shaped edifice with a circular summit caldera of 8 km in diameter. The composition of both composite volcanoes is alkaline and predominantly trachytic, having also minor intermediate lavas. The basaltic fields consist of basalts and trachybasalts, with clinopyroxene and abundant olivine as phenocrysts and also in the groundmass. Textures indicating mixing and mingling processes, such as dusty plagioclases along with clear ones, biotite replaced by anhydrous minerals and two groundmasses with a fluid-fluid relationship, are common in the early pre-caldera stage of Payún Matrú and some post-caldera lavas. The latest post-caldera lavas are trachytic, with clean sanidine phenocrysts without disequilibrium textures. A remarkable characteristic of the Payún Matrú Volcanic Field is the fact that the Payún Matrú caldera is surrounded by basaltic fields at its base, while no basalts were erupted in the caldera region. We propose that the absence of basaltic lavas in the Payún Matrú volcano is due to the presence of a magmatic chamber below it, and that the mafic magmas rising from deeper levels were unable to erupt without interaction with more evolved melts. Intermediate hybrid magmas produced as a consequence of magma mixing and mingling between basaltic and trachytic magmas, are present in the early and mid-history of Payún Matrú volcano. We present here new information about the Quaternary Payún Matrú Volcanic Field derived from field

  17. July 1973 ground survey of active Central American volcanoes

    Science.gov (United States)

    Stoiber, R. E. (Principal Investigator); Rose, W. I., Jr.

    1973-01-01

    The author has identified the following significant results. Ground survey has shown that thermal anomalies of various sizes associated with volcanic activity at several Central American volcanoes should be detectable from Skylab. Anomalously hot areas of especially large size (greater than 500 m in diameter) are now found at Santiaguito and Pacaya volcanoes in Guatemala and San Cristobal in Nicaragua. Smaller anomalous areas are to be found at least seven other volcanoes. This report is completed after ground survey of eleven volcanoes and ground-based radiation thermometry mapping at these same points.

  18. Remote monitoring of volcanic gases using passive Fourier transform spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Love, S.P.; Goff, F.; Counce, D.; Schmidt, S.C. [Los Alamos National Lab., NM (United States); Siebe, C.; Delgado, H. [Univ. Nactional Autonoma de Mexico, Coyoacan (Mexico)

    1999-06-01

    Volcanic gases provide important insights on the internal workings of volcanoes and changes in their composition and total flux can warn of impending changes in a volcano`s eruptive state. In addition, volcanoes are important contributors to the earth`s atmosphere, and understanding this volcanic contribution is crucial for unraveling the effect of anthropogenic gases on the global climate. Studies of volcanic gases have long relied upon direct in situ sampling, which requires volcanologists to work on-site within a volcanic crater. In recent years, spectroscopic techniques have increasingly been employed to obtain information on volcanic gases from greater distances and thus at reduced risk. These techniques have included UV correlation spectroscopy (Cospec) for SO{sub 2} monitoring, the most widely-used technique, and infrared spectroscopy in a variety of configurations, both open- and closed-path. Francis et al. have demonstrated good results using the sun as the IR source. This solar occultation technique is quite useful, but puts rather strong restrictions on the location of instrument and is thus best suited to more accessible volcanoes. In order to maximize the flexibility and range of FTIR measurements at volcanoes, work over the last few years has emphasized techniques which utilize the strong radiance contrast between the volcanic gas plume and the sky. The authors have successfully employed these techniques at several volcanoes, including the White Island and Ruapehu volcanoes in New Zealand, the Kilauea volcano on Hawaii, and Mt. Etna in Italy. But Popocatepetl (5452 m), the recently re-awakened volcano 70 km southeast of downtown Mexico City, has provided perhaps the best examples to date of the usefulness of these techniques.

  19. Determining the stress field in active volcanoes using focal mechanisms

    Directory of Open Access Journals (Sweden)

    Bruno Massa

    2016-11-01

    Full Text Available Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs, Campi Flegrei (217 FPSs and Long Valley Caldera (38,000 FPSs. The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  20. Determining the stress field in active volcanoes using focal mechanisms

    Science.gov (United States)

    Massa, Bruno; D'Auria, Luca; Cristiano, Elena; De Matteo, Ada

    2016-11-01

    Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs), Campi Flegrei (217 FPSs) and Long Valley Caldera (38,000 FPSs). The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  1. Volcano hazards assessment for the Lassen region, northern California

    Science.gov (United States)

    Clynne, Michael A.; Robinson, Joel E.; Nathenson, Manuel; Muffler, L.J. Patrick

    2012-01-01

    The Lassen region of the southernmost Cascade Range is an active volcanic area. At least 70 eruptions have occurred in the past 100,000 years, including 3 in the past 1,000 years, most recently in 1915. The record of past eruptions and the present state of the underlying magmatic and hydrothermal systems make it clear that future eruptions within the Lassen Volcanic Center are very likely. Although the annual probability of an eruption is small, the consequences of some types of eruptions could be severe. Compared to those of a typical Cascade composite volcano, eruptive vents at Lassen Volcanic Center and the surrounding area are widely dispersed, extending in a zone about 50 km wide from the southern boundary of Lassen Volcanic National Park north to the Pit River. This report presents a discussion of volcanic and other geologic hazards in the Lassen area and delineates hazards zones for different types of volcanic activity. Owing to its presence in a national park with significant visitorship, its explosive behavior, and its proximity to regional infrastructure, the Lassen Volcanic Center has been designated a "high threat volcano" in the U.S. Geological Survey National Volcano Early Warning System assessment. Volcanic eruptions are typically preceded by seismic activity and ground deformation, and the Lassen area has a network of seismometers and Global Positioning System stations in place to monitor for early warning of volcanic activity.

  2. Volcanoes muon imaging using Cherenkov telescopes

    CERN Document Server

    Catalano, Osvaldo; Mineo, Teresa; Cusumano, Giancarlo; Maccarone, Maria Concetta; Pareschi, Giovanni

    2015-01-01

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energ...

  3. Radial anisotropy ambient noise tomography of volcanoes

    Science.gov (United States)

    Mordret, Aurélien; Rivet, Diane; Shapiro, Nikolai; Jaxybulatov, Kairly; Landès, Matthieu; Koulakov, Ivan; Sens-Schönfelder, Christoph

    2016-04-01

    The use of ambient seismic noise allows us to perform surface-wave tomography of targets which could hardly be imaged by other means. The frequencies involved (~ 0.5 - 20 s), somewhere in between active seismic and regular teleseismic frequency band, make possible the high resolution imaging of intermediate-size targets like volcanic edifices. Moreover, the joint inversion of Rayleigh and Love waves dispersion curves extracted from noise correlations allows us to invert for crustal radial anisotropy. We present here the two first studies of radial anisotropy on volcanoes by showing results from Lake Toba Caldera, a super-volcano in Indonesia, and from Piton de la Fournaise volcano, a hot-spot effusive volcano on the Réunion Island (Indian Ocean). We will see how radial anisotropy can be used to infer the main fabric within a magmatic system and, consequently, its dominant type of intrusion.

  4. Volcano-tectonic evolution of the polygenetic Kolumbo submarine volcano/Santorini (Aegean Sea)

    Science.gov (United States)

    Hübscher, Christian; Ruhnau, M.; Nomikou, P.

    2015-01-01

    Here we show for the first time the 3D-structural evolution of an explosive submarine volcano by means of reflection seismic interpretation. Four to five vertically stacked circular and cone-shaped units consisting mainly of volcaniclastics build the Kolumbo underwater volcano which experienced its first eruption > 70 ka ago and its last explosive eruption 1650 AD, 7 km NE of Santorini volcano (southern Aegean Sea). The summed volume of volcaniclastics is estimated to range between 13-22 km3. The entire Kolumbo volcanic complex has a height of ≥ 1 km and a diameter of ≥ 11 km. All volcaniclastic units reveal the same transparent reflection pattern strongly suggesting that explosive underwater volcanism was the prevalent process. Growth faults terminate upwards at the base of volcaniclastic units, thus representing a predictor to an eruption phase. Similarities in seismic reflection pattern between Kolumbo and near-by volcanic cones imply that the smaller cones evolved through explosive eruptions as well. Hence, the central Aegean Sea experienced several more explosive eruptions (≥ 23) than previously assumed, thus justifying further risk assessment. However, the eruption columns from the smaller volcanic cones did not reach the air and- consequently - no sub-aerial pyroclastic surge was created. The Anydros basin that hosts Kolumbo volcanic field opened incrementally NW to SE and parallel to the Pliny and Strabo trends during four major tectonic pulses prior to the onset of underwater volcanism.

  5. Geologic map of Medicine Lake volcano, northern California

    Science.gov (United States)

    Donnelly-Nolan, Julie M.

    2011-01-01

    Medicine Lake volcano forms a broad, seemingly nondescript highland, as viewed from any angle on the ground. Seen from an airplane, however, treeless lava flows are scattered across the surface of this potentially active volcanic edifice. Lavas of Medicine Lake volcano, which range in composition from basalt through rhyolite, cover more than 2,000 km2 east of the main axis of the Cascade Range in northern California. Across the Cascade Range axis to the west-southwest is Mount Shasta, its towering volcanic neighbor, whose stratocone shape contrasts with the broad shield shape of Medicine Lake volcano. Hidden in the center of Medicine Lake volcano is a 7 km by 12 km summit caldera in which nestles its namesake, Medicine Lake. The flanks of Medicine Lake volcano, which are dotted with cinder cones, slope gently upward to the caldera rim, which reaches an elevation of nearly 8,000 ft (2,440 m). The maximum extent of lavas from this half-million-year-old volcano is about 80 km north-south by 45 km east-west. In postglacial time, 17 eruptions have added approximately 7.5 km3 to its total estimated volume of 600 km3, and it is considered to be the largest by volume among volcanoes of the Cascades arc. The volcano has erupted nine times in the past 5,200 years, a rate more frequent than has been documented at all other Cascades arc volcanoes except Mount St. Helens.

  6. Atmospheric chemistry in volcanic plumes.

    Science.gov (United States)

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

  7. Spatial Analysis of Volcanoes at Convergent Margins on Earth

    Science.gov (United States)

    Roberts, R. V.; de Silva, S. L.; Meyers, M.

    2009-12-01

    One of the most obvious patterns seen on the surface of the terrestrial planets is the distribution of volcanoes. On Earth, most volcanoes are distributed in volcanic “arcs” that signal the primary relationship between subduction and volcanism. The distributions of major composite volcanoes in volcanic arcs are thought to reflect the primary magmatic pathways from source to surface. Understanding these patterns therefore may allow fundamental controls on the organization of magmatic plumbing in arcs to be identified. Using a control dataset from the Central Volcanic Zone of the Andes (de Silva and Francis, 1991; Springer-Verlag) we have examined several popular approaches to spatial analysis of volcano distribution in several volcanic arcs (Aleutian, Alaskan, Central American, Northern and Southern volcanic zones of the Andes). Restricting our analysis to major volcanoes of similar age, we find that while clustering is visually obvious in many volcanic arcs it has been rejected as a primary signal by previous analytical efforts (e.g. Bremont d'Ars et al (1995)). We show that the fractal box or grid counting method used previously does not detect clusters and statistical methods such as the Kernel Density Analysis or Single-link Cluster Analysis are better suited for cluster detection. Utilizing both ARC GIS and Matlab to conduct density analyses in combination with statistical software SPlus for the appropriate hypothesis testing methods such as the pooled variance t-test, the Welch Modified two sample t-test, and the f-test we find evidence of clustering in four volcanic arcs whose crustal thickness is greater than or equal to 40 kilometres (Central America, CVZ, NVZ, SVZ). We suggest that clustering is the surface manifestation of upper crustal diffusion of primary magmatic pathways, which in other places manifests as a single volcano. The inter-cluster distance is a thus reflection of primary magmatic pathways and thus equivalent to inter-volcano distance

  8. Reply to: Barazzuoli P., Bertini G., Brogi A., Capezzuoli E., Conticelli S., Doveri M., Ellero A., Gianelli G., La Felice S., Liotta D., Marroni M., Manzella A., Meccheri M., Montanari D., Pandeli E., Principe C., Ruggieri R., Sbrana A., Vaselli V., Vezzoli L., 2015. COMMENT ON: "Borgia, A., Mazzoldi, A., Brunori, C.A., Allocca, C., Delcroix, C., Micheli, L., Vercellino, A., Grieco, G., 2014. Volcanic spreading forcing and feedback in geothermal resorvoir development, Amiata Volcano, Italia. J. Volc. Geoth. Res. 284, 16-31". Journal of Volcanology and Geothermal Research, this issue

    Science.gov (United States)

    Borgia, Andrea; Mazzoldi, Alberto; Brunori, Carlo Alberto; Allocca, Carmine; Delcroix, Carlo; Micheli, Luigi; Vercellino, Alberto; Grieco, Giovanni

    2015-09-01

    The volcanic spreading model by Borgia et al. (2014) is accurate in describing the extensional structures found on the edifice and the radial compressional structures existing all around the base of Amiata Volcano. Volcanic conduits, extensional structures, and direct contact between the volcanic rocks and the Tuscan Units, constitute the hydraulic connection between the potable fresh-water aquifer contained in the volcanites and the underlying hydrothermal system. Therefore, gaseous phases tend to flow upward (particularly through faults) carrying pollutants into the freshwater aquifer, while the freshwater recharges (also through primary permeability) the exploited geothermal fields.

  9. Spreading and collapse of big basaltic volcanoes

    Science.gov (United States)

    Puglisi, Giuseppe; Bonforte, Alessandro; Guglielmino, Francesco; Peltier, Aline; Poland, Michael

    2016-04-01

    Among the different types of volcanoes, basaltic ones usually form the most voluminous edifices. Because volcanoes are growing on a pre-existing landscape, the geologic and structural framework of the basement (and earlier volcanic landforms) influences the stress regime, seismicity, and volcanic activity. Conversely, the masses of these volcanoes introduce a morphological anomaly that affects neighboring areas. Growth of a volcano disturbs the tectonic framework of the region, clamps and unclamps existing faults (some of which may be reactivated by the new stress field), and deforms the substratum. A volcano's weight on its basement can trigger edifice spreading and collapse that can affect populated areas even at significant distance. Volcano instability can also be driven by slow tectonic deformation and magmatic intrusion. The manifestations of instability span a range of temporal and spatial scales, ranging from slow creep on individual faults to large earthquakes affecting a broad area. In the frame of MED-SVU project, our work aims to investigate the relation between basement setting and volcanic activity and stability at three Supersite volcanoes: Etna (Sicily, Italy), Kilauea (Island of Hawaii, USA) and Piton de la Fournaise (La Reunion Island, France). These volcanoes host frequent eruptive activity (effusive and explosive) and share common features indicating lateral spreading and collapse, yet they are characterized by different morphologies, dimensions, and tectonic frameworks. For instance, the basaltic ocean island volcanoes of Kilauea and Piton de la Fournaise are near the active ends of long hotspot chains while Mt. Etna has developed at junction along a convergent margin between the African and Eurasian plates and a passive margin separating the oceanic Ionian crust from the African continental crust. Magma supply and plate velocity also differ in the three settings, as to the sizes of the edifices and the extents of their rift zones. These

  10. Volcanism and associated hazards: the Andean perspective

    Science.gov (United States)

    Tilling, R. I.

    2009-12-01

    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and Peru has spurred significant improvements in reducing volcano risk in the Andean region. But much remains to be done.

  11. Volcanism and associated hazards: The Andean perspective

    Science.gov (United States)

    Tilling, R.I.

    2009-01-01

    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and Peru has spurred significant improvements in reducing volcano risk in the Andean region. But much remains to be done.

  12. Mud Volcanoes Formation And Occurrence

    Science.gov (United States)

    Guliyev, I. S.

    2007-12-01

    Mud volcanoes are natural phenomena, which occur throughout the globe. They are found at a greater or lesser scale in Azerbaijan, Turkmenistan, Georgia, on the Kerch and Taman peninsulas, on Sakhalin Island, in West Kuban, Italy, Romania, Iran, Pakistan, India, Burma, China, Japan, Indonesia, Malaysia, New Zealand, Mexico, Colombia, Trinidad and Tobago, Venezuela and Ecuador. Mud volcanoes are most well-developed in Eastern Azerbaijan, where more than 30% of all the volcanoes in the world are concentrated. More than 300 mud volcanoes have already been recognized here onshore or offshore, 220 of which lie within an area of 16,000 km2. Many of these mud volcanoes are particularly large (up to 400 m high). The volcanoes of the South Caspian form permanent or temporary islands, and numerous submarine banks. Many hypotheses have been developed regarding the origin of mud volcanoes. Some of those hypotheses will be examined in the present paper. Model of spontaneous excitation-decompaction (proposed by Ivanov and Guliev, 1988, 2002). It is supposed that one of major factors of the movement of sedimentary masses and formation of hydrocarbon deposits are phase transitions in sedimentary basin. At phase transitions there are abnormal changes of physical and chemical parameters of rocks. Abnormal (high and negative) pressure takes place. This process is called as excitation of the underground environment with periodicity from several tens to several hundreds, or thousand years. The relationship between mud volcanism and the generation of hydrocarbons, particularly methane, is considered to be a critical factor in mud volcano formation. At high flow rates the gas and sediment develops into a pseudo-liquid state and as flow increases the mass reaches the "so-called hover velocity" where mass transport begins. The mass of fluid moves as a quasi-uniform viscous mass through the sediment pile in a piston like manner until expelled from the surface as a "catastrophic eruption

  13. Volcano Monitoring Using Google Earth

    Science.gov (United States)

    Bailey, J. E.; Dehn, J.; Webley, P.; Skoog, R.

    2006-12-01

    At the Alaska Volcano Observatory (AVO), Google Earth is being used as a visualization tool for operational satellite monitoring of the region's volcanoes. Through the abilities of the Keyhole Markup Language (KML) utilized by Google Earth, different datasets have been integrated into this virtual globe browser. Examples include the ability to browse thermal satellite image overlays with dynamic control, to look for signs of volcanic activity. Webcams can also be viewed interactively through the Google Earth interface to confirm current activity. Other applications include monitoring the location and status of instrumentation; near real-time plotting of earthquake hypocenters; mapping of new volcanic deposits; and animated models of ash plumes within Google Earth, created by a combination of ash dispersion modeling and 3D visualization packages. The globe also provides an ideal interface for displaying near real-time information on detected thermal anomalies or "hotspot"; pixels in satellite images with elevated brightness temperatures relative to the background temperature. The Geophysical Institute at the University of Alaska collects AVHRR (Advanced Very High Resolution Radiometer) and MODIS (Moderate Resolution Imaging Spectroradiometer) through its own receiving station. The automated processing that follows includes application of algorithms that search for hotspots close to volcano location, flagging those that meet certain criteria. Further automated routines generate folders of KML placemarkers, which are linked to Google Earth through the network link function. Downloadable KML files have been created to provide links to various data products for different volcanoes and past eruptions, and to demonstrate examples of the monitoring tools developed. These KML files will be made accessible through a new website that will become publicly available in December 2006.

  14. Principal Component Analysis for pattern recognition in volcano seismic spectra

    Science.gov (United States)

    Unglert, Katharina; Jellinek, A. Mark

    2016-04-01

    Variations in the spectral content of volcano seismicity can relate to changes in volcanic activity. Low-frequency seismic signals often precede or accompany volcanic eruptions. However, they are commonly manually identified in spectra or spectrograms, and their definition in spectral space differs from one volcanic setting to the next. Increasingly long time series of monitoring data at volcano observatories require automated tools to facilitate rapid processing and aid with pattern identification related to impending eruptions. Furthermore, knowledge transfer between volcanic settings is difficult if the methods to identify and analyze the characteristics of seismic signals differ. To address these challenges we have developed a pattern recognition technique based on a combination of Principal Component Analysis and hierarchical clustering applied to volcano seismic spectra. This technique can be used to characterize the dominant spectral components of volcano seismicity without the need for any a priori knowledge of different signal classes. Preliminary results from applying our method to volcanic tremor from a range of volcanoes including K¯ı lauea, Okmok, Pavlof, and Redoubt suggest that spectral patterns from K¯ı lauea and Okmok are similar, whereas at Pavlof and Redoubt spectra have their own, distinct patterns.

  15. Volcanic mercury in Pinus canariensis

    Science.gov (United States)

    Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

    2013-08-01

    Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg-1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg-1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg-1) and bark (6.0 μg kg-1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

  16. Catastrophic volcanism

    Science.gov (United States)

    Lipman, Peter W.

    1988-01-01

    Since primitive times, catastrophes due to volcanic activity have been vivid in the mind of man, who knew that his activities in many parts of the world were threatened by lava flows, mudflows, and ash falls. Within the present century, increasingly complex interactions between volcanism and the environment, on scales not previously experienced historically, have been detected or suspected from geologic observations. These include enormous hot pyroclastic flows associated with collapse at source calderas and fed by eruption columns that reached the stratosphere, relations between huge flood basalt eruptions at hotspots and the rifting of continents, devastating laterally-directed volcanic blasts and pyroclastic surges, great volcanic-generated tsunamis, climate modification from volcanic release of ash and sulfur aerosols into the upper atmosphere, modification of ocean circulation by volcanic constructs and attendent climatic implications, global pulsations in intensity of volcanic activity, and perhaps triggering of some intense terrestrial volcanism by planetary impacts. Complex feedback between volcanic activity and additional seemingly unrelated terrestrial processes likely remains unrecognized. Only recently has it become possible to begin to evaluate the degree to which such large-scale volcanic processes may have been important in triggering or modulating the tempo of faunal extinctions and other evolutionary events. In this overview, such processes are examined from the viewpoint of a field volcanologist, rather than as a previous participant in controversies concerning the interrelations between extinctions, impacts, and volcanism.

  17. Applications of geophysical methods to volcano monitoring

    Science.gov (United States)

    Wynn, Jeff; Dzurisin, Daniel; Finn, Carol A.; Kauahikaua, James P.; Lahusen, Richard G.

    2006-01-01

    The array of geophysical technologies used in volcano hazards studies - some developed originally only for volcano monitoring - ranges from satellite remote sensing including InSAR to leveling and EDM surveys, campaign and telemetered GPS networks, electronic tiltmeters and strainmeters, airborne magnetic and electromagnetic surveys, short-period and broadband seismic monitoring, even microphones tuned for infrasound. They include virtually every method used in resource exploration except large-scale seismic reflection. By “geophysical ” we include both active and passive methods as well as geodetic technologies. Volcano monitoring incorporates telemetry to handle high-bandwith cameras and broadband seismometers. Critical geophysical targets include the flux of magma in shallow reservoir and lava-tube systems, changes in active hydrothermal systems, volcanic edifice stability, and lahars. Since the eruption of Mount St. Helens in Washington State in 1980, and the eruption at Pu’u O’o in Hawai’i beginning in 1983 and still continuing, dramatic advances have occurred in monitoring technology such as “crisis GIS” and lahar modeling, InSAR interferograms, as well as gas emission geochemistry sampling, and hazards mapping and eruption predictions. The on-going eruption of Mount St. Helens has led to new monitoring technologies, including advances in broadband Wi-Fi and satellite telemetry as well as new instrumentation. Assessment of the gap between adequate monitoring and threat at the 169 potentially dangerous Holocene volcanoes shows where populations are dangerously exposed to volcanic catastrophes in the United States and its territories . This paper focuses primarily on Hawai’ian volcanoes and the northern Pacific and Cascades volcanoes. The US Geological Survey, the US National Park System, and the University of Utah cooperate in a program to monitor the huge Yellowstone volcanic system, and a separate observatory monitors the restive Long Valley

  18. Newberry Volcano's youngest lava flows

    Science.gov (United States)

    Robinson, Joel E.; Donnelly-Nolan, Julie M.; Jensen, Robert A.

    2015-01-01

    Most of Newberry Volcano's youngest lava flows are found within the Newberry National Volcanic Monument in central Oregon. Established November 5, 1990, the monument is managed by the U.S. Forest Service as part of the Deschutes National Forest. Since 2011, a series of aerial surveys over the monument collected elevation data using lidar (light detection and ranging) technology, which uses lasers to directly measure the ground surface. These data record previously unseen detail in the volcano’s numerous lava flows and vents. On average, a laser return was collected from the ground’s surface every 2.17 feet (ft) with ±1.3 inches vertical precision.

  19. VOLCANIC TSUNAMI GENERATING SOURCE MECHANISMS IN THE EASTERN CARIBBEAN REGION

    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis

    2004-01-01

    Full Text Available Earthquakes, volcanic eruptions, volcanic island flank failures and underwater slides have generated numerous destructive tsunamis in the Caribbean region. Convergent, compressional and collisional tectonic activity caused primarily from the eastward movement of the Caribbean Plate in relation to the North American, Atlantic and South American Plates, is responsible for zones of subduction in the region, the formation of island arcs and the evolution of particular volcanic centers on the overlying plate. The inter-plate tectonic interaction and deformation along these marginal boundaries result in moderate seismic and volcanic events that can generate tsunamis by a number of different mechanisms. The active geo-dynamic processes have created the Lesser Antilles, an arc of small islands with volcanoes characterized by both effusive and explosive activity. Eruption mechanisms of these Caribbean volcanoes are complex and often anomalous. Collapses of lava domes often precede major eruptions, which may vary in intensity from Strombolian to Plinian. Locally catastrophic, short-period tsunami-like waves can be generated directly by lateral, direct or channelized volcanic blast episodes, or in combination with collateral air pressure perturbations, nuéss ardentes, pyroclastic flows, lahars, or cascading debris avalanches. Submarine volcanic caldera collapses can also generate locally destructive tsunami waves. Volcanoes in the Eastern Caribbean Region have unstable flanks. Destructive local tsunamis may be generated from aerial and submarine volcanic edifice mass edifice flank failures, which may be triggered by volcanic episodes, lava dome collapses, or simply by gravitational instabilities. The present report evaluates volcanic mechanisms, resulting flank failure processes and their potential for tsunami generation. More specifically, the report evaluates recent volcanic eruption mechanisms of the Soufriere Hills volcano on Montserrat, of Mt. Pel

  20. Monitoring gas emissions can help forecast volcanic eruptions

    Science.gov (United States)

    Kern, Christoph; Maarten de Moor,; Bo Galle,

    2015-01-01

    As magma ascends in active volcanoes, dissolved volatiles partition from melt into a gas phase, rise, and are released into the atmosphere from volcanic vents. The major components of high-temperature volcanic gas are typically water vapor, carbon dioxide, and sulfur dioxide. 

  1. Translating Volcano Hazards Research in the Cascades Into Community Preparedness

    Science.gov (United States)

    Ewert, J. W.; Driedger, C. L.

    2015-12-01

    Research by the science community into volcanic histories and physical processes at Cascade volcanoes in the states of Washington, Oregon, and California has been ongoing for over a century. Eruptions in the 20th century at Lassen Peak and Mount St. Helen demonstrated the active nature of Cascade volcanoes; the 1980 eruption of Mount St. Helens was a defining moment in modern volcanology. The first modern volcano hazards assessments were produced by the USGS for some Cascade volcanoes in the 1960s. A rich scientific literature exists, much of which addresses hazards at these active volcanoes. That said community awareness, planning, and preparation for eruptions generally do not occur as a result of a hazard analyses published in scientific papers, but by direct communication with scientists. Relative to other natural hazards, volcanic eruptions (or large earthquakes, or tsunami) are outside common experience, and the public and many public officials are often surprised to learn of the impacts volcanic eruptions could have on their communities. In the 1980s, the USGS recognized that effective hazard communication and preparedness is a multi-faceted, long-term undertaking and began working with federal, state, and local stakeholders to build awareness and foster community action about volcano hazards. Activities included forming volcano-specific workgroups to develop coordination plans for volcano emergencies; a concerted public outreach campaign; curriculum development and teacher training; technical training for emergency managers and first responders; and development of hazard information that is accessible to non-specialists. Outcomes include broader ownership of volcano hazards as evidenced by bi-national exchanges of emergency managers, community planners, and first responders; development by stakeholders of websites focused on volcano hazards mitigation; and execution of table-top and functional exercises, including evacuation drills by local communities.

  2. Preliminary geochemical characterization of volcanic and geothermal fluids discharged from the Ecuadorian volcanic arc.

    OpenAIRE

    Inguaggiato, S.; Hidalgo, S.; Beate, B.; Bourquin, J.

    2009-01-01

    In Ecuador, magmatism results from the subduction of the Nazca Plate beneath the North Western part of South America (Pennington, 1981; Kellogg and Vega, 1995; Witt et al., 2006). North of 2.5°S, the Ecuadorian Quaternary volcanic arc is characterized by about 60 volcanoes distributed in three different parallel chains. Many of these volcanoes are potentially active or currently in activity and display associated geothermal fields. South of this latitude, no active arc is present in Ecuador. ...

  3. The origin of the Hawaiian Volcano Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Dvorak, John [University of Hawaii' s Institute for Astronomy (United States)

    2011-05-15

    I first stepped through the doorway of the Hawaiian Volcano Observatory in 1976, and I was impressed by what I saw: A dozen people working out of a stone-and-metal building perched at the edge of a high cliff with a spectacular view of a vast volcanic plain. Their primary purpose was to monitor the island's two active volcanoes, Kilauea and Mauna Loa. I joined them, working for six weeks as a volunteer and then, years later, as a staff scientist. That gave me several chances to ask how the observatory had started.

  4. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael P.; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Ben

    2017-08-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  5. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Benjamin

    2017-01-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  6. Global monsoon precipitation responses to large volcanic eruptions.

    Science.gov (United States)

    Liu, Fei; Chai, Jing; Wang, Bin; Liu, Jian; Zhang, Xiao; Wang, Zhiyuan

    2016-04-11

    Climate variation of global monsoon (GM) precipitation involves both internal feedback and external forcing. Here, we focus on strong volcanic forcing since large eruptions are known to be a dominant mechanism in natural climate change. It is not known whether large volcanoes erupted at different latitudes have distinctive effects on the monsoon in the Northern Hemisphere (NH) and the Southern Hemisphere (SH). We address this issue using a 1500-year volcanic sensitivity simulation by the Community Earth System Model version 1.0 (CESM1). Volcanoes are classified into three types based on their meridional aerosol distributions: NH volcanoes, SH volcanoes and equatorial volcanoes. Using the model simulation, we discover that the GM precipitation in one hemisphere is enhanced significantly by the remote volcanic forcing occurring in the other hemisphere. This remote volcanic forcing-induced intensification is mainly through circulation change rather than moisture content change. In addition, the NH volcanic eruptions are more efficient in reducing the NH monsoon precipitation than the equatorial ones, and so do the SH eruptions in weakening the SH monsoon, because the equatorial eruptions, despite reducing moisture content, have weaker effects in weakening the off-equatorial monsoon circulation than the subtropical-extratropical volcanoes do.

  7. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    primitive basalts and trachybasalts but also more evolved samples from the retroarc region and the larger volcanoes Payún Matrú and Payún Liso are presented. The samples cover a broad range of compositions from intraplate lavas similar to ocean island basalts to arc andesites. A common feature found...... Pleistocene times. These basalts mark the end of a period of shallow subduction of the Nazca slab beneath the Payenia province and volcanism in the Nevado volcanic field apparently followed the downwarping slab in a north-northwest direction ending in the Northern Segment. The northern Payenia basalts...... the literature. The Nevado basalts have been modelled by 4-10 % melting of a primitive mantle added 1-5 % upper continental crust. In the southern Payenia province, intraplate basalts dominate. The samples from the Payún Matrú and Río Colorado volcanic fields are apparently unaffected by the subducting slab...

  8. Scaling properties of planetary calderas and terrestrial volcanic eruptions

    Directory of Open Access Journals (Sweden)

    L. Sanchez

    2012-11-01

    Full Text Available Volcanism plays an important role in transporting internal heat of planetary bodies to their surface. Therefore, volcanoes are a manifestation of the planet's past and present internal dynamics. Volcanic eruptions as well as caldera forming processes are the direct manifestation of complex interactions between the rising magma and the surrounding host rock in the crust of terrestrial planetary bodies. Attempts have been made to compare volcanic landforms throughout the solar system. Different stochastic models have been proposed to describe the temporal sequences of eruptions on individual or groups of volcanoes. However, comprehensive understanding of the physical mechanisms responsible for volcano formation and eruption and more specifically caldera formation remains elusive. In this work, we propose a scaling law to quantify the distribution of caldera sizes on Earth, Mars, Venus, and Io, as well as the distribution of calderas on Earth depending on their surrounding crustal properties. We also apply the same scaling analysis to the distribution of interevent times between eruptions for volcanoes that have the largest eruptive history as well as groups of volcanoes on Earth. We find that when rescaled with their respective sample averages, the distributions considered show a similar functional form. This result implies that similar processes are responsible for caldera formation throughout the solar system and for different crustal settings on Earth. This result emphasizes the importance of comparative planetology to understand planetary volcanism. Similarly, the processes responsible for volcanic eruptions are independent of the type of volcanism or geographical location.

  9. Volcanic Plume Measurements with UAV (Invited)

    Science.gov (United States)

    Shinohara, H.; Kaneko, T.; Ohminato, T.

    2013-12-01

    Volatiles in magmas are the driving force of volcanic eruptions and quantification of volcanic gas flux and composition is important for the volcano monitoring. Recently we developed a portable gas sensor system (Multi-GAS) to quantify the volcanic gas composition by measuring volcanic plumes and obtained volcanic gas compositions of actively degassing volcanoes. As the Multi-GAS measures variation of volcanic gas component concentrations in the pumped air (volcanic plume), we need to bring the apparatus into the volcanic plume. Commonly the observer brings the apparatus to the summit crater by himself but such measurements are not possible under conditions of high risk of volcanic eruption or difficulty to approach the summit due to topography etc. In order to overcome these difficulties, volcanic plume measurements were performed by using manned and unmanned aerial vehicles. The volcanic plume measurements by manned aerial vehicles, however, are also not possible under high risk of eruption. The strict regulation against the modification of the aircraft, such as installing sampling pipes, also causes difficulty due to the high cost. Application of the UAVs for the volcanic plume measurements has a big advantage to avoid these problems. The Multi-GAS consists of IR-CO2 and H2O gas analyzer, SO2-H2O chemical sensors and H2 semiconductor sensor and the total weight ranges 3-6 kg including batteries. The necessary conditions of the UAV for the volcanic plumes measurements with the Multi-GAS are the payloads larger than 3 kg, maximum altitude larger than the plume height and installation of the sampling pipe without contamination of the exhaust gases, as the exhaust gases contain high concentrations of H2, SO2 and CO2. Up to now, three different types of UAVs were applied for the measurements; Kite-plane (Sky Remote) at Miyakejima operated by JMA, Unmanned airplane (Air Photo Service) at Shinomoedake, Kirishima volcano, and Unmanned helicopter (Yamaha) at Sakurajima

  10. Assimilating aircraft-based measurements to improve forecast accuracy of volcanic ash transport

    NARCIS (Netherlands)

    Fu, G.; Lin, H.X.; Heemink, A.W.; Segers, A.J.; Lu, S.; Palsson, T.

    2015-01-01

    The 2010 Eyjafjallajökull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash transport forecast in recent years. For forecasting the volcanic ash transport after eruption onset, a volcanic ash transport and diffusion model (VATDM) needs

  11. Assimilating aircraft-based measurements to improve forecast accuracy of volcanic ash transport

    NARCIS (Netherlands)

    Fu, G.; Lin, H.X.; Heemink, A.W.; Segers, A.J.; Lu, S.; Palsson, T.

    2015-01-01

    The 2010 Eyjafjallajokull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash transport forecast in recent years. For forecasting the volcanic ash transport after eruption onset, a volcanic ash transport and diffusion model (VATDM) needs

  12. Model-based aviation advice on distal volcanic ash clouds by assimilating aircraft in situ measurements

    NARCIS (Netherlands)

    Fu, G.; Heemink, A.; Lu, S.; Segers, A.; Weber, K.; Lin, H.X.

    2016-01-01

    The forecast accuracy of distal volcanic ash clouds is important for providing valid aviation advice during volcanic ash eruption. However, because the distal part of volcanic ash plume is far from the volcano, the influence of eruption information on this part becomes rather indirect and uncertain,

  13. Sutter Buttes-the lone volcano in California's Great Valley

    Science.gov (United States)

    Hausback, Brain P.; Muffler, L.J. Patrick; Clynne, Michael A.

    2011-01-01

    The volcanic spires of the Sutter Buttes tower 2,000 feet above the farms and fields of California's Great Valley, just 50 miles north-northwest of Sacramento and 11 miles northwest of Yuba City. The only volcano within the valley, the Buttes consist of a central core of volcanic domes surrounded by a large apron of fragmental volcanic debris. Eruptions at the Sutter Buttes occurred in early Pleistocene time, 1.6 to 1.4 million years ago. The Sutter Buttes are not part of the Cascade Range of volcanoes to the north, but instead are related to the volcanoes in the Coast Ranges to the west in the vicinity of Clear Lake, Napa Valley, and Sonoma Valley.

  14. Temporal relationships between the variations of diffuse gaseous emanations and the explosive activity of some active volcanoes of Costa-Rica, examples at the Arenal, Irazu and at the Rincon de la Vieja; Relations temporelles entre les variations des emanations gazeuses diffuses et l`activite explosive de quelques volcans actifs du Costa-Rica, exemples a l`Arenal, l`Irazu et au Rincon de la Vieja

    Energy Technology Data Exchange (ETDEWEB)

    Baubron, J.C. [BRGM, 45 - Orleans (France); Allard, P. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Direction des Sciences de la Matiere; Fernandez, E. [Obviscori, Heridia (Costa Rica); Hammouya, G. [Observatoire de la Soufriere, IPG-P, le Houelmont, 97 - Gourgeyre (France); Soto, G.J. [ICE, San Jose (Costa Rica)

    1996-12-31

    The surveillance of the temporal evolution of radon and helium concentrations in the carbon dioxide of crater fumaroles and gaseous emanations is performed since 1992 on the Irazu, Arenal, Poas and Rincon de la Vieja volcanoes in Costa-Rica. The {sup 3}He/{sup 4}He ratio is used as an indicator of the deep origin of the volcanic gas while radon is an indicator of the CO{sub 2} flux. Radon measurements performed on the Irazu show a continuous decay of radon concentration in the intra-crater fumaroles with an important increase of the gaseous flux since 1992. On the contrary, the external fumaroles on the NW flank were characterized by an important increase in radon concentration in 1994 with a stable flux. The radon surveillance performed in soils around the volcano has shown an intense increase of the diffuse gaseous flows probably linked to the micro-seismic activity of the volcano. Similar observations are reported for the Rincon de la Vieja volcano and correlated with its eruptive history and its phreatic and phreato-magmatic activity. Short paper. (J.S.).

  15. Volcanic caves of East Africa - an overview</