WorldWideScience

Sample records for active andean volcanism

  1. 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 (Colombia) killed about 25 000 people - the worst volcanic disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and 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

  2. Application of ASAR-ENVISAT Data for Monitoring Andean Volcanic Activity : Results From Lastarria-Azufre Volcanic Complex (Chile-Argentina)

    Science.gov (United States)

    Froger, J.; Remy, D.; Bonvalot, S.; Franco Guerra, M.

    2005-12-01

    Since the pioneer study on Mount Etna by Massonnet et al., in 1995, several works have illustrated the promising potentiality of Synthetic Aperture Radar Interferometry (INSAR) for the monitoring of volcanoes. In the case of wide, remote or hazardous volcanic areas, in particular, INSAR represents a safer and more economic way to acquire measurements than from ground based geodetic networks. Here we present the preliminary results of an interferometric survey made with ASAR-ENVISAT data on a selection of South American volcanoes where deformation signals had been previously evidenced or are expected. An interesting result is the detection of a present-day active ground deformation on the Azufre-Lastarria area (Chile-Argentina) indicating that process, identified during 1998-2000 by Pritchard and Simmons (2004) from ERS data, is still active. The phase signal visible on ASAR interferograms (03/2003-06/2005) is roughly elliptical with a 45 km NNE-SSW major axis. Its amplitude increases as a function of time and is compatible with ground uplift in the line of sight of the satellite. The ASAR time series (up to 840 days, 7 ASAR images) indicates variable deformation rate that might confirm the hypothesis of a non uniform deformation process. We investigated the origin and the significance of the deformation using various source modelling strategies (analytical and numerical). The observed deformation can be explained by the infilling of an elliptical magmatic reservoir lying between 7 and 10 km depth. The deformation could represent the first stage of a new caldera forming as it is correlated with a large, although subtle, topographic depression surrounded by a crown of monogenetic centers. A short wavelength inflation has also been detected on Lastaria volcano. It could result from the on-going infilling of a small subsurface magmatic reservoir, eventually supplied by the deeper one. All these observations point out the need of a closer monitoring of this area in

  3. Oxygen Isotopes in Intra-Back Arc Basalts from the Andean Southern Volcanic Zone

    Science.gov (United States)

    Parks, B. H.; Wang, Z.; Saal, A. E.; Frey, F. A.; Blusztajn, J.

    2013-12-01

    The chemical compositions of volcanic rocks from the Andean Southern Volcanic Zone (SVZ) reflect complex and dynamic interactions among the subducting oceanic lithosphere, the mantle wedge, and the overlying continental crust. Oxygen isotope ratios of olivine phenocrysts can be a useful means to identifying their relative contributions to the arc magmatism. In this study, we report high-precision oxygen-isotope ratios of olivine phenocrysts in a set of intra-back arc basalts from the SVZ. The samples were collected from monogenetic cinder cones east of the volcanic front (35-39 degrees S), and have been geochemically well-characterized with major and trace element contents, and Sr-Nd-Pb isotope compositions. Compared to lavas from the volcanic front, these intra-back arc lavas have similar radiogenic isotope, and a more alkalic and primitive (higher MgO content) chemical composition. We determined the oxygen-isotope ratios using the CO2-laser-fluorination method set up at the Department of Geology and Geophysics, Yale University following the techniques reported in Wang et al (2011). The samples were analyzed with standards of Gore Mountain Garnet (5.77×0.12‰ 1σ; Valley et al., 1995) and Kilbourne Hole Olivine (5.23×0.07‰ 1σ; Sharp, 1990) in order to account for minor changes in the vacuum line during analyses. The obtained δ18OSMOW values of olivine phenocrysts from the intra-back arc basalts vary from 4.98×0.01 to 5.34×0.01‰. This range, surprisingly, is similar to the δ18O values of olivines from mantle peridotites (5.2×0.2‰). Preliminary results indicate significant correlations of 87Sr/86Sr, 143Nd/144Nd and trace element ratios of the basaltic matrix with the δ18O values of olivine phenocrysts, indicating at least three components involved in the formation of the arc volcanism. By comparing the δ18O with the variations of major and trace element contents (e.g., MgO, TiO2 and Ni), and trace element ratios (e.g. Ba/Nb), we evaluate the effects

  4. Holocene tephrostratigraphy of southern Chiloé Continental (Andean southern volcanic zone; ~43°S), Chile

    Science.gov (United States)

    Lachowycz, S.; Smith, V. C.; Pyle, D. M.; Mather, T. A.

    2012-12-01

    The eruptive history of the volcanoes in the southern part of the Andean Southern Volcanic Zone (42.5-45°S) is very poorly constrained: only several late Quaternary eruptions have been identified, mostly from study of sparse roadcuts [1]. In this study, we further constrain the Holocene explosive eruption history around 43°S by identifying and analysing tephra layers preserved in a ~3.25m long peat core from Cuesta Moraga [2], ~35km east of Yanteles volcano. Cryptotephra was extracted following the method of [3], in addition to macrotephra; owing to the vicinity of the sampling site to the tephra sources, cryptotephra was found throughout the core stratigraphy, but was sufficiently variable in concentration that discrete layers were identifiable and attributed to specific eruptions. Chemical analysis of the glass by electron microprobe shows that the tephra layers originate from a number of volcanoes in the region. This new tephrostratigraphy improves our knowledge of the important history of explosive volcanism in this area, potentially tying the tephrostratigraphies of surrounding areas (e.g., [4]) and allowing improved evaluation of regional volcanic risk. [1] Naranjo, J.A.., and C. R. Stern, 2004. Holocene tephrochronology of the southernmost part (42°30'-45°S) of the Andean Southern Volcanic Zone. Revista geológica de Chile, 31, pp. 225-240. [2] Heusser, C.J., et al., 1992. Paleoecology of late Quaterary deposits in Chiloé Continental, Chile. Revista Chilena de Historia Natural, 65, pp. 235-245. [3] Blockley, S.P.E., et al., 2005. A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments. Quaternary Science Reviews, 24, pp. 1952-1960. [4] Watt, S.F.L., et al., 2011. Holocene tephrochronology of the Hualaihue region (Andean southern volcanic zone, ~42°S), southern Chile. Quaternary International, 246, pp. 324-343.

  5. Rapid uplift in Laguna del Maule volcanic field of the Andean Southern Volcanic Zone (Chile) measured by satellite radar interferometry

    Science.gov (United States)

    Feigl, K.; Ali, T.; Singer, B. S.; Pesicek, J. D.; Thurber, C. H.; Jicha, B. R.; Lara, L. E.; Hildreth, E. W.; Fierstein, J.; Williams-Jones, G.; Unsworth, M. J.; Keranen, K. M.

    2011-12-01

    The Laguna del Maule (LdM) volcanic field of the Andean Southern Volcanic Zone extends over 500 square kilometers and comprises more than 130 individual vents. As described by Hildreth et al. (2010), the history has been defined from sixty-eight Ar/Ar and K-Ar dates. Silicic eruptions have occurred throughout the past 3.7 Ma, including welded ignimbrite associated with caldera formation at 950 ka, small rhyolitic eruptions between 336 and 38 ka, and a culminating ring of 36 post-glacial rhyodacite and rhyolite coulees and domes that encircle the lake. Dating of five post-glacial flows implies that these silicic eruptions occurred within the last 25 kyr. Field relations indicate that initial eruptions comprised modest volumes of mafic rhyodacite magma that were followed by larger volumes of high silica rhyolite. The post-glacial flare-up of silicic magmatism from vents distributed around the lake, is unprecedented in the history of this volcanic field. Using satellite radar interferometry (InSAR), Fournier et al. (2010) measured uplift at a rate of more than 180 mm/year between 2007 and 2008 in a round pattern centered on the west side of LdM. More recent InSAR observations suggest that rapid uplift has continued from 2008 through early 2011. In contrast, Fournier et al. found no measurable deformation in an interferogram spanning 2003 through 2004. In this study, we model the deformation field using the General Inversion of Phase Technique (GIPhT), as described by Feigl and Thurber (2009). Two different models fit the data. The first model assumes a sill at ~5 km depth has been inflating at a rate of more than 20 million cubic meters per year since 2007. The second model assumes that the water level in the lake dropped at a rate of 20 m/yr from January 2007 through February 2010, thus reducing the load on an elastic simulation of the crust. The rate of intrusion inferred from InSAR is an order of magnitude higher than the average rate derived from well-dated arc

  6. Tectonic Constraints on the Evolution of Geothermal Systems in the Central Andean Volcanic Zone (CAVZ)

    Science.gov (United States)

    Veloso, E. E.; Tardani, D.; Aron, F.; Elizalde, J. D.; Sanchez-Alfaro, P.; Godoy, B.

    2017-12-01

    South of 19°S, geothermal fields and Pliocene-to-Holocene volcanic centers of the Central Andean Volcanic Zone are spatially associated with distinct, large-scale fault systems disrupting the volcanic arc, which control the architecture and dynamics of the fluids reservoirs at shallow crustal levels. Based on an extensive compilation of structural, lithological and isotopic data, and satellite imagery band-ratio analyses, we produced detailed maps of 13 areas comprising 19 identified and/or potential geothermal fields, to examine if particular local-scale tectonic configurations are associated to fluids migrating from different crustal levels. We defined three main tectonic environments according to the specific, kilometer-scale structural arrangement and its spatial relation to the geothermal surface manifestations. T1, dominated by left-lateral, pure strike-slip motion on a NW-trending duplex-like geometry with geothermal fields located along the faults - in turn distributed into five major subparallel zones cutting across the orogenic belt between ca. 20° and 27°S. T2, dominated by shortening on a series of N-trending thrust faults and fault-propagated folds, cut and displaced by the above mentioned NW-trending faults, with geothermal fields hosted at fault intersections and at fold hinges. And T3, characterized by transtension accommodated by NW-to-WNW-trending left-lateral/normal faults, with hot-springs lying along the fault traces. Interestingly, each of the independently defined tectonic environments has distinctive helium (in fluids) and strontium (in lavas) isotopic signatures and estimated geothermal reservoir temperatures. T1 shows a large 4He contribution, low 87Sr/86Sr ratio and temperatures varying between ca. 220°-310°C; T3 low 4He and high 87Sr/86Sr ratio and temperature (260°-320°C); T2 isotopic values fall between T1 and T3, yet showing the lowest (130°-250°C) temperatures. We suggest that these particular isotopic signatures are due to

  7. Petrology and oxygen isotope geochemistry of the Pucon ignimbrite - Southern Andean volcanic zone, Chile: Implications for genesis of mafic ignimbrites

    International Nuclear Information System (INIS)

    McCurry, Michael; Schmidt, Keegan

    2001-01-01

    Although mafic components of dominantly intermediate to silicic ignimbrites are rather common, voluminous, dominantly mafic ignimbrites are rare (e.g., Smith, 1979; cf. Freundt and Schmincke, 1995). Volcan Villarrica, the most active composite volcano in South America, located in the Southern Andean Volcanic Zone (SAVZ, Lopez-Escobar and Moreno, 1994a), has produced two such ignimbrites, respectively the Lican and Pucon Ignimbrites, in the last 14,000 years (Clavero, 1996). The two ignimbrites are low-Si andesite and basaltic-andesite to low-Si andesite, respectively, the former about twice as voluminous as the later (10 and 5 km 3 ). Eruption of the ignimbrites produced calderas respectively 5 and 2 km in diameter (Moreno, 1995; Clavero, 1996). In addition to its mafic bulk composition, the Pucon Ignimbrite (PI) is also distinguished by numerous xenolithic fragments among and also within magmatic pyroclasts. Many of these are fragments of granitoid rocks. Volcan Villarrica has also produced numerous smaller mafic ignimbrites and pyroclastic surge deposits, as well as dominantly basaltic fallout and lava flows (Lopez-Escobar and Moreno, 1994; Moreno, 1995; Clavero, 1996; Hickey-Vargas et al., 1989; Tormey et al., 1991). Reasons for the unusual style of mafic explosive activity at Volcan Villarrica are unclear. Clavero (1996), based upon an exemplary thesis-study of the physical volcanology and petrology of the PI, suggests it formed in response to a sequence of events beginning with injection of a shallow basaltic andesite magma chamber by hotter basaltic magma. In his model mixing and heat transfer between the two magmas initiated a violent Strombolian eruption that destabilized the chamber causing infiltration of large amounts of meteoric-water saturated country rocks. The Pucon Ignimbrite formed in response to subsequent phreatomagmatic interactions. In contrast, Lopez-Escobar and Moreno (1994) infer on geochemical grounds that volatiles leading to the explosive

  8. Assessing the effects of climate and volcanism on diatom and chironomid assemblages in an Andean lake near Quito, Ecuador

    Directory of Open Access Journals (Sweden)

    Neal Michelutti

    2015-12-01

    Full Text Available The tropical Andes are undergoing climate changes that rival those occurring anywhere else on the planet, and are likely to have profound consequences for ecosystems. Paleolimnological investigations of remote mountain lakes can provide details of past environmental change, especially where monitoring data are absent. Here, we reconstruct fossil diatom and chironomid communities spanning the last several hundred years from an Andean lake located in an ecological reserve near Quito, Ecuador. Both diatoms and chironomids recorded assemblage shifts reflective of changing climate conditions. The diatoms are likely responding primarily to temperature-related limnological changes, recording an increase in the number of planktonic taxa in the most recent sediments. This change is consistent with warmer conditions that result in enhanced periods of thermal stratification, allowing planktonic species to proliferate. The chironomids appear to respond mainly to a change in precipitation regime, recording a greater number of terrestrial and semi-terrestrial taxa that have been transported to the lake. A thick tephra deposit at the base of the sediment core affected both diatom and chironomid assemblages. The diatoms registered a change in species composition highlighting the ability of certain taxa to rapidly colonize new environments. In contrast, the chironomids showed a marked drop in abundance immediately following the tephra, but no change in species composition. In both cases the ecological response was short-lived, illustrating the resiliency of the lake to return to baseline conditions following volcanic inputs.

  9. The volcanism of the western part of the Los Frailes Meseta (Bolivia): a representative example of the Andean volcanism since the Upper Oligocene

    International Nuclear Information System (INIS)

    Leroy, L.; Jimenez, N.

    1996-01-01

    The Los Frailes Meseta (Bolivia) is one of the large tertiary ignimbritic fields of the inner volcanic arc from Central Andes (Central Volcanic Zone. CVZ), in contact zone between the Altiplano to the west and the Eastern Cordillera to the east. Field observations and mineralogical and geochemical studies (major and trace elements) lead to distinguish two types of volcanism in the western border to the Meseta. During the Middle Miocene and Pliocene, the volcanic activity can be subdivided into three pyroclastic emission cycles, the Larco, Coroma and Pliocene ignimbrites, the first two being separated by the Quechua 2 orogeny. All these ignimbrites are very similar and correspond to peraluminous rhyolites to rhyodacites. In the studies area, the Coroma cycle is the only one where an ignimbrite-less evolved resurgent dome association can be observed. Beside these ignimbrites, isolated small lava flows and domes overlay and/or intrude all the other formations. They are meta-aluminous lavas with a shoshonitic affinity. A quaternary age can be attributed to his second volcanism. These two volcanic types are well-known in the CVZ and are related to the different deformation stages, either compressional or extensional, which occur alternately in the Cordillera since 26 Ma. (authors). 61 refs., 12 figs., 3 tabs

  10. Dinasour extinction and volcanic activity

    Science.gov (United States)

    Gledhill, J. A.

    There is at present some controversy about the reason for the mass extinction of dinosaurs and other forms of life at the end of the Cretaceous. A suggestion by Alvarez et al. [1980] that this was due to the collision of the earth with a meteorite 10 km or so in diameter has excited considerable interest [Silver and Schultz, 1982] and also some criticism [Stanley, 1984]. A recent publication [Wood, 1984] describing the catastrophic effects of a relatively minor lava flow in Iceland suggests that intense volcanic activity could have played a large part in the extinctions. In this letter it is pointed out that the Deccan lava flows in India took place in the appropriate time and may well have been of sufficient magnitude to be a major factor in the Cretaceous-Tertiary (C-T) boundary catastrophe.

  11. Volcanic eruptions and solar activity

    Science.gov (United States)

    Stothers, Richard B.

    1989-01-01

    The historical record of large volcanic eruptions from 1500 to 1980 is subjected to detailed time series analysis. In two weak but probably statistically significant periodicities of about 11 and 80 yr, the frequency of volcanic eruptions increases (decreases) slightly around the times of solar minimum (maximum). Time series analysis of the volcanogenic acidities in a deep ice core from Greenland reveals several very long periods ranging from about 80 to about 350 yr which are similar to the very slow solar cycles previously detected in auroral and C-14 records. Solar flares may cause changes in atmospheric circulation patterns that abruptly alter the earth's spin. The resulting jolt probably triggers small earthquakes which affect volcanism.

  12. Active Volcanic Eruptions on Io

    Science.gov (United States)

    1996-01-01

    Six views of the volcanic plume named Prometheus, as seen against Io's disk and near the bright limb (edge) of the satellite by the SSI camera on the Galileo spacecraft during its second (G2) orbit of Jupiter. North is to the top of each frame. To the south-southeast of Prometheus is another bright spot that appears to be an active plume erupting from a feature named Culann Patera. Prometheus was active 17 years ago during both Voyager flybys, but no activity was detected by Voyager at Culann. Both of these plumes were seen to glow in the dark in an eclipse image acquired by the imaging camera during Galileo's first (G1) orbit, and hot spots at these locations were detected by Galileo's Near-Infrared Mapping Spectrometer.The plumes are thought to be driven by heating sulfur dioxide in Io's subsurface into an expanding fluid or 'geyser'. The long-lived nature of these eruptions requires that a substantial supply of sulfur dioxide must be available in Io's subsurface, similar to groundwater. Sulfur dioxide gas condenses into small particles of 'snow' in the expanding plume, and the small particles scatter light and appear bright at short wavelengths. The images shown here were acquired through the shortest-wavelength filter (violet) of the Galileo camera. Prometheus is about 300 km wide and 75 km high and Culann is about 150 km wide and less than 50 km high. The images were acquired on September 4, 1996 at a range of 2,000,000 km (20 km/pixel resolution). Prometheus is named after the Greek fire god and Culann is named after the Celtic smith god.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can

  13. Tellurium in active volcanic environments: Preliminary results

    Science.gov (United States)

    Milazzo, Silvia; Calabrese, Sergio; D'Alessandro, Walter; Brusca, Lorenzo; Bellomo, Sergio; Parello, Francesco

    2014-05-01

    Tellurium is a toxic metalloid and, according to the Goldschmidt classification, a chalcophile element. In the last years its commercial importance has considerably increased because of its wide use in solar cells, thermoelectric and electronic devices of the last generation. Despite such large use, scientific knowledge about volcanogenic tellurium is very poor. Few previous authors report result of tellurium concentrations in volcanic plume, among with other trace metals. They recognize this element as volatile, concluding that volcanic gases and sulfur deposits are usually enriched with tellurium. Here, we present some results on tellurium concentrations in volcanic emissions (plume, fumaroles, ash leachates) and in environmental matrices (soils and plants) affected by volcanic emissions and/or deposition. Samples were collected at Etna and Vulcano (Italy), Turrialba (Costa Rica), Miyakejima, Aso, Asama (Japan), Mutnovsky (Kamchatka) at the crater rims by using common filtration techniques for aerosols (polytetrafluoroethylene filters). Filters were both eluted with Millipore water and acid microwave digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Volcanic ashes emitted during explosive events on Etna and Copahue (Argentina) were analyzed for tellurium bulk composition and after leaching experiments to evaluate the soluble fraction of tellurium. Soils and leaves of vegetation were also sampled close to active volcanic vents (Etna, Vulcano, Nisyros, Nyiragongo, Turrialba, Gorely and Masaya) and investigated for tellurium contents. Preliminary results showed very high enrichments of tellurium in volcanic emissions comparing with other volatile elements like mercury, arsenic, thallium and bismuth. This suggests a primary transport in the volatile phase, probably in gaseous form (as also suggested by recent studies) and/or as soluble salts (halides and/or sulfates) adsorbed on the surface of particulate particles and ashes. First

  14. Temporal and geochemical evolution of Miocene volcanism in the Andean back-arc between 36°S and 38°S and U-series analyses of young volcanic centers in the arc and back-arc, Argentina

    DEFF Research Database (Denmark)

    Dyhr, Charlotte Thorup

    New 40Ar/39Ar, major and trace element, and Sr, Nd and Pb isotopic data for the c. 24-7 Ma volcanic rocks from the Andean back-arc (35°S – 38°S) in the Mendoza and Neuquén (Argentina) regions shed light on the Miocene evolution of the back-arc of the Southern Volcanic Zone. Incipient shallowing......-Sr-Pb isotopic compositions. The arc-like component that dominates the geochemistry of the Palaoco rocks is absent in both the Early Miocene and the Pliocene-Pleistocene in the same area. Young volcanic Provinces in the main arc, retro-arc and back-arc are further investigated by U-series analyses which confirm...... the fluid-enriched nature of arc-related rocks (U-excess are found in most rocks) and the more OIB-like nature of the Payún Matrú complex (Th-exsess is observed in all rocks). The fluid addition to the mantle source is modeled revealing timescales of 10 – 100 ka for the fluid enrichment. For the back...

  15. Isotopic clues to magmatic source regions for neogene Andean volcanic rocks in the El Teniente area near 38oS latitude

    International Nuclear Information System (INIS)

    Kay, Suzanne Mahlburg; Kurtz, A.C

    2001-01-01

    The origin of isotopic variations in Central Andean arc lavas is a long-standing problem that involves identifying mantle and crustal source regions. Advances have come from analyzing temporal and spatial variations in constrained tectonic settings. The purpose here is to highlight the similarities of temporal variations in an east-west transect of Neogene magmatic units near 34 O S latitude with those from a south-north transect along the modern Southern Volcanic Zone (SVZ, e.g. Hildreth and Moorbath 1988, Tormey et al. 1991). The comparison shows the importance of crustal thickening processes associated with compressional shortening and of lithospheric scale adjustments associated with eastward migration of the arc front on magma sources. Sr, Nd and Pb isotopic analyses of 27 Neogene volcanic and plutonic samples from the El Teniente area are presented in Table 1 and plotted along with some analyses from Skewes and Stern (1994) and Stern and Skewes (1995) in Figure 2. The data show a clear progression from older samples with more 'depleted' isotopic signatures (lower 87 Sr/ 86 Sr and Pb isotopic ratios, higher εNd) to younger samples with more 'enriched' signatures (higher 87 Sr/ 86 Sr and Pb isotopic ratios, lower εNd). In detail, four temporal and spatial groups marked by discontinuities in isotopic trends can be defined. Within each group, εNd tends to decrease and 87 Sr/ 86 Sr ratios to increase with SiO2 concentration (au)

  16. Towards understanding of carbon stocks and stabilization in volcanic ash soils in natural Andean ecosystems of northern Ecuador

    NARCIS (Netherlands)

    Tonneijck, F.H.; Jansen, B.; Nierop, K.G.J.; Verstraten, J.M.; Sevink, J.; de Lange, L.

    2010-01-01

    Volcanic ash soils contain very large stocks of soil organic matter (SOM) per unit area. Consequently, they constitute potential sources or sinks for the greenhouse gas carbon dioxide. Whether soils become a net carbon source or sink with climate and/or land-use change depends on the stability of

  17. Wound healing activity of Ullucus tuberosus, an Andean tuber crop

    OpenAIRE

    Nathalie Heil; Karent Bravo; Andrés Montoya; Sara Robledo; Edison Osorio

    2017-01-01

    Objective: This study was designed to investigate the wound healing activity of aqueous extracts of Ullucus tuberosus (U. tuberosus) using in vitro models. Methods: Lyophilized pulp and acetone extracts of U. tuberosus were produced using ultrasound extraction. The capacity for collagenase activation was evaluated using fluorescence detection of the enzymatic activity. Then, the influence of U. tuberosus extracts on cell proliferation, cell migration and synthesis of the extracellular matr...

  18. 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.

  19. 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

  20. Phenolic compound contents and antioxidant activity in plants with nutritional and/or medicinal properties form the Peruvian Andean region

    NARCIS (Netherlands)

    Chirinos, R.; Pedreschi Plasencia, R.P.; Rogez, H.

    2013-01-01

    Total phenolic compounds (TPC) and antioxidant activities using different assays (DPPH, ABTS and ORAC) in fruits, grains, leaves, seeds, roots and tubers from 27 different Peruvian Andean plants used in folk medicine or/and as food by the native population were evaluated in order to use these as

  1. Phytosynthesis and photocatalytic activity of magnetite (Fe_3O_4) nanoparticles using the Andean blackberry leaf

    International Nuclear Information System (INIS)

    Kumar, Brajesh; Smita, Kumari; Cumbal, Luis; Debut, Alexis; Galeas, Salome; Guerrero, Victor H.

    2016-01-01

    In the present study, a simple, low cost, and ecofriendly synthesis of magnetite nanoparticles (Fe_3O_4 NPs) has been developed using Andean blackberry leaf extract. UV–vis spectroscopy technique were used to study the initial formation of Fe_3O_4 NPs. Morphology, crystallinity and surface properties of nanoparticles were studied using transmission electron microscopy (TEM), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Thermal gravimetric (TG) techniques. TEM and DLS characterization indicated the formation of spherical Fe_3O_4 NPs of average size 54.5 ± 24.6 nm. XRD and FTIR studies confirmed the existence of the cubic spinel phase of Fe_3O_4 NPs and Fe−O peak at 570 cm"−"1, whereas TG analysis indicated that the nanoparticles contain 94% metal and 6% capping ligand. It has been observed that, as-synthesized Fe_3O_4 NPs exhibited photocatalytic activity for degradation of organic dyes such as methylene blue (k = 0.0105475 min"−"1), congo red (k = 0.0043240 min"−"1), and methyl orange (k = 0.0028930 min"−"1), efficiently. The antioxidant activity of Fe_3O_4 NPs against 1, 1-diphenyl-2-picrylhydrazyl were also evaluated. - Highlights: • We report extracellular phytosynthesis of Fe_3O_4 nanoparticles using the Andean blackberry leaf. • The synthesized Fe_3O_4 nanoparticles are spherical and average size is 54.5 ± 24.6 nm. • It showed enhanced photocatalytic activity and weak antioxidant efficacy. • Environmentally benign, non-toxic and cost-effective method is suggested.

  2. U-series radioactive disequilibria 238U-230Th-226Ra: discussions on sources and processes responsible for volcanism of the Andean cordillera and on the deglaciation in Iceland

    International Nuclear Information System (INIS)

    Chmeleff, J.

    2005-10-01

    Thanks to precise analyses of uranium series radioactive disequilibria, permitted by improvements of mass spectrometry data acquisition and optimization of chemistry, two questions were tackled and answers about the periods of glaciation in Iceland and the petrogenesis of Andean lavas were proposed. Two methods were used to date lava flows from the Reykjanes peninsula and the island of Heimaey, in Iceland, directly linked to the periods of deglaciation or reheating around the last ice age. An original method based on the use of segregation veins present in the lava flows has been developed. Thanks to the formation of this particular geological object this methods permits to be freed from xeno-crystals when using the internal isochron method in the 238 U- 230 Th system. Using this method some constraints are brought both on the quaternary geology of the area of Reykjavik and on the age of the end of the Wurm glaciation on Heirnaey. In parallel, due to the homogeneity of the historical and Holocene lavas of the Reykjanes peninsula, regarding the ( 230 Th/ 232 Th) and Th/U ratios, it is possible to derive the ( 230 Th/ 232 Th) ratio in time to determine the age of lava flows installed during the ice age. Thus we confirmed that the magnetic excursion recorded in the Skalamaelifell lava flow is most probably the same one as that of Laschamp-Olby and that at this time (approximately 48.000 years) the Reykjanes peninsula was entirely covered with a glacier. Thanks to this method the extent of the glacier was also constrained by dating of a picritic shield around 22.000 years, thus the peninsula has to be free of any ice cap despite the fact that glaciation is the most intense around this time.Then Andean arc magmas petrogenesis was constrained in time and space. Almost systematic excesses of 226 Ra compared to 230 Th in lavas of austral, southern and northern volcanic zones of the Andes (AVZ, SVZ and NVZ) constrain the ascending time from the source to the surface after

  3. Volcanic Gases and Hot Spring Water to Evaluate the Volcanic Activity of the Mt. Baekdusan

    Science.gov (United States)

    Yun, S. H.; Lee, S.; Chang, C.

    2017-12-01

    This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu, also known as Changbaishan on the North Korea(DPRK)-China border, during the period from July 2015 to August 2016. Also, we confirmed the errors that HCO3- concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved CO2 in hot spring waters was analyzed using gas chromatograph in Lee et al.(2014). Improving this, from 2015, we used TOC-IC to analysis dissolved CO2. Also, we analyzed the Na2CO3 standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of the Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the HCO3-concentrations of 2014 samples. During the period of study, CO2/CH4 ratios in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction condition, and carbon in volcanic gases become more favorable to distribute into CH4 or CO than CO2. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of CO2which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cations, and some trace elements (As, Cd, Re).This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMIPA 2015-3060.

  4. Using Volcanic Lightning Measurements to Discern Variations in Explosive Volcanic Activity

    Science.gov (United States)

    Behnke, S. A.; Thomas, R. J.; McNutt, S. R.; Edens, H. E.; Krehbiel, P. R.; Rison, W.

    2013-12-01

    VHF observations of volcanic lightning have been made during the recent eruptions of Augustine Volcano (2006, Alaska, USA), Redoubt Volcano (2009, Alaska, USA), and Eyjafjallajökull (2010, Iceland). These show that electrical activity occurs both on small scales at the vent of the volcano, concurrent with an eruptive event and on large scales throughout the eruption column during and subsequent to an eruptive event. The small-scale discharges at the vent of the volcano are often referred to as 'vent discharges' and are on the order of 10-100 meters in length and occur at rates on the order of 1000 per second. The high rate of vent discharges produces a distinct VHF signature that is sometimes referred to as 'continuous RF' radiation. VHF radiation from vent discharges has been observed at sensors placed as far as 100 km from the volcano. VHF and infrasound measurements have shown that vent discharges occur simultaneously with the onset of eruption, making their detection an unambiguous indicator of explosive volcanic activity. The fact that vent discharges are observed concurrent with explosive volcanic activity indicates that volcanic ejecta are charged upon eruption. VHF observations have shown that the intensity of vent discharges varies between eruptive events, suggesting that fluctuations in eruptive processes affect the electrification processes giving rise to vent discharges. These fluctuations may be variations in eruptive vigor or variations in the type of eruption; however, the data obtained so far do not show a clear relationship between eruption parameters and the intensity or occurrence of vent discharges. Further study is needed to clarify the link between vent discharges and eruptive behavior, such as more detailed lightning observations concurrent with tephra measurements and other measures of eruptive strength. Observations of vent discharges, and volcanic lightning observations in general, are a valuable tool for volcano monitoring, providing a

  5. The Role of Volcanic Activity in Climate and Global Change

    KAUST Repository

    Stenchikov, Georgiy L.

    2015-09-23

    Explosive volcanic eruptions are magnificent events that in many ways affect the Earth\\'s natural processes and climate. They cause sporadic perturbations of the planet\\'s energy balance, activating complex climate feedbacks and providing unique opportunities to better quantify those processes. We know that explosive eruptions cause cooling in the atmosphere for a few years, but we have just recently realized that volcanic signals can be seen in the subsurface ocean for decades. The volcanic forcing of the previous two centuries offsets the ocean heat uptake and diminishes global warming by about 30%. The explosive volcanism of the twenty-first century is unlikely to either cause any significant climate signal or to delay the pace of global warming. The recent interest in dynamic, microphysical, chemical, and climate impacts of volcanic eruptions is also excited by the fact that these impacts provide a natural analogue for climate geoengineering schemes involving deliberate development of an artificial aerosol layer in the lower stratosphere to counteract global warming. In this chapter we aim to discuss these recently discovered volcanic effects and specifically pay attention to how we can learn about the hidden Earth-system mechanisms activated by explosive volcanic eruptions. To demonstrate these effects we use our own model results when possible along with available observations, as well as review closely related recent publications.

  6. Explosive Volcanic Activity at Extreme Depths: Evidence from the Charles Darwin Volcanic Field, Cape Verdes

    Science.gov (United States)

    Kwasnitschka, T.; Devey, C. W.; Hansteen, T. H.; Freundt, A.; Kutterolf, S.

    2013-12-01

    Volcanic eruptions on the deep sea floor have traditionally been assumed to be non-explosive as the high-pressure environment should greatly inhibit steam-driven explosions. Nevertheless, occasional evidence both from (generally slow-) spreading axes and intraplate seamounts has hinted at explosive activity at large water depths. Here we present evidence from a submarine field of volcanic cones and pit craters called Charles Darwin Volcanic Field located at about 3600 m depth on the lower southwestern slope of the Cape Verdean Island of Santo Antão. We examined two of these submarine volcanic edifices (Tambor and Kolá), each featuring a pit crater of 1 km diameter, using photogrammetric reconstructions derived from ROV-based imaging followed by 3D quantification using a novel remote sensing workflow, aided by sampling. The measured and calculated parameters of physical volcanology derived from the 3D model allow us, for the first time, to make quantitative statements about volcanic processes on the deep seafloor similar to those generated from land-based field observations. Tambor cone, which is 2500 m wide and 250 m high, consists of dense, probably monogenetic medium to coarse-grained volcaniclastic and pyroclastic rocks that are highly fragmented, probably as a result of thermal and viscous granulation upon contact with seawater during several consecutive cycles of activity. Tangential joints in the outcrops indicate subsidence of the crater floor after primary emplacement. Kolá crater, which is 1000 m wide and 160 m deep, appears to have been excavated in the surrounding seafloor and shows stepwise sagging features interpreted as ring fractures on the inner flanks. Lithologically, it is made up of a complicated succession of highly fragmented deposits, including spheroidal juvenile lapilli, likely formed by spray granulation. It resembles a maar-type deposit found on land. The eruption apparently entrained blocks of MORB-type gabbroic country rocks with

  7. Ejection age of volcano rocks and trend of volcanic activity

    Energy Technology Data Exchange (ETDEWEB)

    Sakaguchi, Keiichi

    1987-10-01

    This report is II-7 of an interim report on research and development of the Sunshine Project for 1986. This report considers on the trend of volcanic activities in the South of Kyushu area. K-Ar age measurement was newly made and reported. Age values obtained were 1.09 plus minus 0.21 Ma for Nagaoyama andesite, 1.33 plus minus 0.18 Ma for Nozato andesite, and 0.3 plus minus 0.1 Ma for Imuta volcanos. Including these age values, from the age values and their distribution of the volcanic rocks in the South Kyushu district, the following three districts were selected to represent the volcanic activities since the Pliocene Epoch. As these districts are mutually overwrapped, verification at these overwrapped districts are necessary. (4 figs, 1 tab, 12 refs)

  8. 78 FR 15031 - Agency Information Collection Activities: Andean Trade Preferences Act

    Science.gov (United States)

    2013-03-08

    ... Management and Budget (OMB) approval. All comments will become a matter of public record. In this document..., Andean Trade Promotion and Drug Eradication Act (ATPDEA) Certificate of Origin. This form can be used... 17. Type of Review: Extension (without change). Affected Public: Businesses. ATPA Certificate of...

  9. Characterization of the volcanic eruption emissions using neutron activation analysis

    International Nuclear Information System (INIS)

    Pla, Rita R.; Tafuri, Victoria V.

    1997-01-01

    Characterization of the volcanic particulate material has been performed by analyzing aerosols and ashes with instrumental neutron activation analysis. Crustal enrichment factors were calculated using the elemental concentration and clustering techniques, and multivariate analysis were done. The analytical and data treatment methodologies allowed the sample differentiation from their geographical origin viewpoint, based on their chemical composition patterns, which are related to the deposit formation processes, which consist of direct deposition from the volcanic cloud, and removal by wind action after the end of the eruption, and and finally the deposition. (author). 8 refs., 5 figs

  10. Radon in active volcanic areas of Southern Italy

    International Nuclear Information System (INIS)

    Avino, R.; Capaldi, G.; Pece, R.

    1999-01-01

    The paper presents the preliminary data dealing with the variations in time of the radiogenic gas radon in soils and waters of many active volcanic areas of Southern Italy. The greatest differences in Rn content of the investigated volcanic areas are: Ischia and Campi Flegrei, which have more Rn than Vesuvio and Volcano, both in soils and in waters. The thermalized waters of Ischia are enriched in Rn 15 times with respect to soils, while in the other areas soils and underground waters have comparable Rn contents

  11. Division of volcanic activity cycles in the late mesozoic in South Jiangxi and North Guangdong

    International Nuclear Information System (INIS)

    Li Qinglong; Wu Jianhua

    1999-01-01

    Based on stratigraphical unconformity, rock association, fossil assemblage, isotope age and tectonic features, the volcanic activity in late Mesozoic in south Jiangxi and north Guandong can be divided into four cycles: Yutian volcanic activity cycle, Lianhuazhai volcanic activity cycle. Banshi volcanic activity cycle and Nanxiong volcanic activity cycle. Yutian volcanic cycle which occurs in middle Jurassic epoch is the bimodal rock association composed of rhyolite and basalt. Lianhuazhai volcanic cycle which occurs in late Jurassic epoch is unimodal rock association composed of rhyolite. Banshi volcanic cycle occurs from the late stage of early Cretaceous to the early stage of late Cretaceous epoch. There are two types of rock associations related to this cycle: unimodal rock association composed of rhyolite or basalt and bimodal rock association composed of rhyolite and basalt. Nanxiong volcanic activity cycle which occurred in late stage of late Cretaceous epoch is the unimodal rock association composed of basalt which is the interlayer of the red sedimentary series

  12. Volcanic ash in ancient Maya ceramics of the limestone lowlands: implications for prehistoric volcanic activity in the Guatemala highlands

    Science.gov (United States)

    Ford, Anabel; Rose, William I.

    1995-07-01

    In the spirit of collaborative research, Glicken and Ford embarked on the problem of identifying the source of volcanic ash used as temper in prehistoric Maya ceramics. Verification of the presence of glass shards and associated volcanic mineralogy in thin sections of Maya ceramics was straightforward and pointed to the Guatemala Highland volcanic chain. Considering seasonal wind rose patterns, target volcanoes include those from the area west of and including Guatemala City. Joint field research conducted in 1983 by Glicken and Ford in the limestone lowlands of Belize and neighboring Guatemala, 300 km north of the volcanic zone and 150 km from the nearest identified ash deposits, was unsuccessful in discovering local volcanic ash deposits. The abundance of the ash in common Maya ceramic vessels coupled with the difficulties of long-distance procurement without draft animals lead Glicken to suggest that ashfall into the lowlands would most parsimoniously explain prehistoric procurement; it literally dropped into their hands. A major archaeological problem with this explanation is that the use of volcanic ash occurring over several centuries of the Late Classic Period (ca. 600-900 AD). To accept the ashfall hypothesis for ancient Maya volcanic ash procurement, one would have to demonstrate a long span of consistent volcanic activity in the Guatemala Highlands for the last half of the first millennium AD. Should this be documented through careful petrographic, microprobe and tephrachronological studies, a number of related archaeological phenomena would be explained. In addition, the proposed model of volcanic activity has implications for understanding volcanism and potential volcanic hazards in Central America over a significantly longer time span than the historic period. These avenues are explored and a call for further collaborative research of this interdisciplinary problem is extended in this paper.

  13. Active avoidance from a crude oil soluble fraction by an Andean paramo copepod.

    Science.gov (United States)

    Araújo, Cristiano V M; Moreira-Santos, Matilde; Sousa, José P; Ochoa-Herrera, Valeria; Encalada, Andrea C; Ribeiro, Rui

    2014-09-01

    Several oil spills due to ruptures in the pipeline oil systems have occurred at the Andean paramo. A sample of this crude oil was mixed with water from a nearby Andean lagoon and the toxicity of the soluble fraction was assessed through lethal and avoidance assays with a locally occurring copepod (Boeckella occidentalis intermedia). The integration of mortality and avoidance aimed at predicting the immediate decline of copepod populations facing an oil leakage. The 24-h median lethal PAH concentration was 42.7 (26.4-91.6) µg L(-1). In the 12-h avoidance assay, 30% avoidance was recorded at the highest PAH concentration (19.4 µg L(-1)). The mortality at this PAH concentration would be of 25% and, thus, the population immediate decline would be of 55%. The inclusion of non-forced exposure testing with the quantification of the avoidance response in environmental risk assessments is, therefore, supported due to underestimation of the lethal assays.

  14. Andean waterways

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    Andean Waterways explores the politics of natural resource use in the Peruvian Andes in the context of climate change and neoliberal expansion. It does so through careful ethnographic analysis of the constitution of waterways, illustrating how water becomes entangled in a variety of political......, social, and cultural concerns. Set in the highland town of Recuay in Ancash, the book traces the ways in which water affects political and ecological relations as glaciers recede. By looking at the shared waterways of four villages located in the foothills of Cordillera Blanca, it addresses pertinent...

  15. Andean waterways

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    , social, and cultural concerns. Set in the highland town of Recuay in Ancash, the book traces the ways in which water affects political and ecological relations as glaciers recede. By looking at the shared waterways of four villages located in the foothills of Cordillera Blanca, it addresses pertinent......Andean Waterways explores the politics of natural resource use in the Peruvian Andes in the context of climate change and neoliberal expansion. It does so through careful ethnographic analysis of the constitution of waterways, illustrating how water becomes entangled in a variety of political...... questions concerning water governance and rural lives....

  16. Active Volcanism on Io as Seen by Galileo SSI

    Science.gov (United States)

    McEwen, A.S.; Keszthelyi, L.; Geissler, P.; Simonelli, D.P.; Carr, M.H.; Johnson, T.V.; Klaasen, K.P.; Breneman, H.H.; Jones, T.J.; Kaufman, J.M.; Magee, K.P.; Senske, D.A.; Belton, M.J.S.; Schubert, G.

    1998-01-01

    Active volcanism on Io has been monitored during the nominal Galileo satellite tour from mid 1996 through late 1997. The Solid State Imaging (SSI) experiment was able to observe many manifestations of this active volcanism, including (1) changes in the color and albedo of the surface, (2) active airborne plumes, and (3) glowing vents seen in eclipse. About 30 large-scale (tens of kilometers) surface changes are obvious from comparison of the SSI images to those acquired by Voyager in 1979. These include new pyroclastic deposits of several colors, bright and dark flows, and caldera-floor materials. There have also been significant surface changes on Io during the Galileo mission itself, such as a new 400-km-diameter dark pyroclastic deposit around Pillan Patera. While these surface changes are impressive, the number of large-scale changes observed in the four months between the Voyager 1 and Voyager 2 flybys in 1979 suggested that over 17 years the cumulative changes would have been much more impressive. There are two reasons why this was not actually the case. First, it appears that the most widespread plume deposits are ephemeral and seem to disappear within a few years. Second, it appears that a large fraction of the volcanic activity is confined to repeated resurfacing of dark calderas and flow fields that cover only a few percent of Io's surface. The plume monitoring has revealed 10 active plumes, comparable to the 9 plumes observed by Voyager. One of these plumes was visible only in the first orbit and three became active in the later orbits. Only the Prometheus plume has been consistently active and easy to detect. Observations of the Pele plume have been particularly intriguing since it was detected only once by SSI, despite repeated attempts, but has been detected several times by the Hubble Space Telescope at 255 nm. Pele's plume is much taller (460 km) than during Voyager 1 (300 km) and much fainter at visible wavelengths. Prometheus-type plumes (50

  17. Unzen volcanic rocks as heat source of geothermal activity

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masao; Sugiyama, Hiromi

    1987-03-25

    Only a few radiometric ages have been reported so far for the Unzen volcanic rocks. In this connection, in order to clarify the relation between volcanism and geothermal activity, fission track ages of zircon seperated from the Unzen volcanic rocks in western Kyushu have been dated. Since all the rocks are thought to be young, the external surface re-etch method was adopted. The results are that the age and standard error of the basal volcaniclastic rocks of the Tatsuishi formation are 0.28 +- 0.05 Ma and 0.25 +- 0.05 Ma. The next oldest Takadake lavas range from 0.26 to 0.20 Ma. The Kusenbudake lavas fall in a narrow range from 0.19 to 0.17 Ma. The latest Fugendake lavas are younger than 0.07 Ma.In conclusion, the most promising site for geothermal power generation is the Unzen hot spring field because of its very high temperature. After that, comes the Obama hot spring field because of the considerable high temperature chemically estimated. In addition, the northwestern area of the Unzen volcanic region will be promising for electric power generation in spite of no geothermal manifestations, since its volcanos are younger than 0.2 Ma. (14 figs, 14 tabs, 22 refs)

  18. Sedimentary response to volcanic activity in the Okinawa Trough since the last deglaciation

    Institute of Scientific and Technical Information of China (English)

    蒋富清; 李安春; 李铁刚

    2010-01-01

    To investigate the relationship between volcanic activity and sediment record on regional and temporal scales,158 surface sediment samples were collected from the East China Sea Shelf to the northern Okinawa Trough (OT),and two cores recovered in the northern and southern OT,respectively.Mineralogy,grain-size,and geochemical analyses of those samples show that:1) volcanic glass,volcanic-type pyroxene,hypersthenes,and magnetite increase in sediment influenced by volcanic activity;2) sediment grain sizes (and...

  19. Microgravity change as a precursor to volcanic activity

    Science.gov (United States)

    Rymer, Hazel

    1994-07-01

    In recent decades, systematic microgravity studies over some 20 active volcanoes in Central America, Iceland, Italy, Japan, Papua New Guinea and the USA have provided valuable data on sub-surface mass redistribution associated with volcanic activity. Concurrent data on ground deformation are essential to the unambiguous interpretation of gravity changes. In some instances, gravity and elevation vary along the free-air or Bouguer gradients, implying that there has been no sub-surface mass or density change, respectively. Where there are residual gravity changes after correction for elevation changes, magma movements in sub-surface chambers, feeder systems, vents and fissures (dykes) or water table variations are proposed. Although detailed interpretations depend on local circumstances and the calculations depend on source geometry, in general, the smallest residual gravity changes are associated with eruptions from volatile-poor basaltic vents and at extensional rift zones, whereas the highest residual values occur at explosive, subduction-related stratocones built from volatile-rich andesitic magma. The most intriguing, yet difficult, data to interpret derive from large-volume, infrequently erupting volcanic systems where caldera unrest is now becoming well documented and the ultimate hazards are most severe. Mass increases during inflation followed by limited mass loss during subsequent deflation typify these structures.

  20. The 42-kDa coat protein of Andean potato mottle virus acts as a transcriptional activator in yeast

    Directory of Open Access Journals (Sweden)

    Vidal M.S.

    2002-01-01

    Full Text Available Interactions of viral proteins play an important role in the virus life cycle, especially in capsid assembly. Andean potato mottle comovirus (APMoV is a plant RNA virus with a virion formed by two coat proteins (CP42 and CP22. Both APMoV coat protein open reading frames were cloned into pGBT9 and pGAD10, two-hybrid system vectors. HF7c yeast cells transformed with the p9CP42 construct grew on yeast dropout selection media lacking tryptophan and histidine. Clones also exhibited ß-galactosidase activity in both qualitative and quantitative assays. These results suggest that CP42 protein contains an amino acid motif able to activate transcription of His3 and lacZ reporter genes in Saccharomyces cerevisiae. Several deletions of the CP42 gene were cloned into the pGBT9 vector to locate the region involved in this activation. CP42 constructions lacking 12 residues from the C-terminal region and another one with 267 residues deleted from the N-terminus are still able to activate transcription of reporter genes. However, transcription activation was not observed with construction p9CP42deltaC57, which does not contain the last 57 amino acid residues. These results demonstrate that a transcription activation domain is present at the C-terminus of CP42 between residues 267 and 374.

  1. Galileo SSI Observations of Volcanic Activity at Tvashtar Catena, Io

    Science.gov (United States)

    Milazzo, M. P.; Keszthely, L. P.; Radebaugh, J.; Davies, A. G.; Turtle, E. P.; Geissler, P.; Klaasen, K. P.; McEwen, A. S.

    2005-01-01

    Introduction: We report on the analysis of the Galileo SSI's observations of the volcanic activity at Tvashtar Catena, Io as discussed by Milazzo et al. Galileo's Solid State Imager (SSI) observed Tvashtar Catena (63 deg N, 120 deg W) four times between November 1999 and October 2001, providing a unique look at the distinctive high latitude volcanism on Io. The November 1999 observation spatially resolved, for the first time, an active extraterrestrial fissure eruption. The brightness temperature of the lavas at the November 1999 fissure eruption was 1300 K. The second observation (orbit I27, February 2000) showed a large (approx. 500 sq km) region with many, small spots of hot, active lava. The third observation was taken in conjunction with a Cassini observation in December 2000 and showed a Pele-like plume deposition ring, while the Cassini images revealed a 400 km high Pele-type plume above the Catena. The final Galileo SSI observation of Tvashtar was acquired in October 2001, and all obvious (to SSI) activity had ceased, although data from Galileo's Near Infrared Mapping Spectrometer (NIMS) indicated that there was still significant thermal emission from the Tvashtar region. We have concentrated on analyzing the style of eruption during orbit I27 (February 2000). Comparison with a lava flow cooling model indicates that the behavior of the Tvashtar eruption during I27 does not match that of "simple" advancing lava flows. Instead, it may be an active lava lake or a complex set of lava flows with episodic, overlapping (in time and space) eruptions.

  2. Constraints on the origin and evolution of magmas in the Payún Matrú Volcanic Field, Quaternary Andean back-arc of western Argentina

    DEFF Research Database (Denmark)

    Hernadno, I R; Aragón, E; Frei, Robert

    2014-01-01

    and Sr–Nd isotopic compositions of the basaltic lavas and Payún Matrú rocks indicate that the trachytes of Payún Matrú are the result of fractional crystallization of basaltic parent magmas without significant upper crustal contamination, and that the basalts have a geochemical similarity to ocean island...... basalt (La/Nb = 0·8–1·5, La/Ba = 0·05–0·08). The Sr–Nd isotopic compositions of the basaltic to trachytic rocks range between 0·703813 and 0·703841 (87Sr/86Sr) and 0·512743 and 0·512834 (143Nd/144Nd). Mass-balance and Rayleigh fractionation models support the proposed origin of the trachytes...... that the basaltic lavas originated in the asthenospheric mantle, probably within the spinel stability field and beneath an attenuated continental lithosphere in the back-arc area. The lack of a slab-fluid signature in the Payún Matrú Volcanic Field rocks, along with unpublished and published geophysical results...

  3. Nondestructive neutron activation analysis of volcanic samples: Hawaii

    International Nuclear Information System (INIS)

    Zoller, W.H.; Finnegan, D.L.; Crowe, B.

    1986-01-01

    Samples of volcanic emissions have been collected between and during eruptions of both Kilauea and Mauna Loa volcanoes during the last three years. Airborne particles have been collected on Teflon filters and acidic gases on base-impregnated cellulose filters. Chemically neutral gas-phase species are collected on charcoal-coated cellulose filters. The primary analytical technique used is nondestructive neutron activation analysis, which has been used to determine the quantities of up to 35 elements on the different filters. The use of neutron activation analysis makes it possible to analyze for a wide range of elements in the different matrices used for the collection and to learn about the distribution between particles and gas phases for each of the elements

  4. Phytosynthesis and photocatalytic activity of magnetite (Fe{sub 3}O{sub 4}) nanoparticles using the Andean blackberry leaf

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Brajesh, E-mail: krmbraj@gmail.com [Centro de Nanociencia y Nanotecnologia, Universidad de las Fuerzas Armadas ESPE, Av. Gral. Rumiñahui s/n, Sangolqui, P.O. BOX 171-5-231B (Ecuador); Department of Chemistry, TATA College, Kolhan University, Chaibasa, 833202, Jharkhand (India); Smita, Kumari; Cumbal, Luis; Debut, Alexis [Centro de Nanociencia y Nanotecnologia, Universidad de las Fuerzas Armadas ESPE, Av. Gral. Rumiñahui s/n, Sangolqui, P.O. BOX 171-5-231B (Ecuador); Galeas, Salome; Guerrero, Victor H. [Laboratorio de Nuevos Materiales, Departamento de Materiales, Escuela Politécnica Nacional, Quito (Ecuador)

    2016-08-15

    In the present study, a simple, low cost, and ecofriendly synthesis of magnetite nanoparticles (Fe{sub 3}O{sub 4} NPs) has been developed using Andean blackberry leaf extract. UV–vis spectroscopy technique were used to study the initial formation of Fe{sub 3}O{sub 4} NPs. Morphology, crystallinity and surface properties of nanoparticles were studied using transmission electron microscopy (TEM), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Thermal gravimetric (TG) techniques. TEM and DLS characterization indicated the formation of spherical Fe{sub 3}O{sub 4} NPs of average size 54.5 ± 24.6 nm. XRD and FTIR studies confirmed the existence of the cubic spinel phase of Fe{sub 3}O{sub 4} NPs and Fe−O peak at 570 cm{sup −1}, whereas TG analysis indicated that the nanoparticles contain 94% metal and 6% capping ligand. It has been observed that, as-synthesized Fe{sub 3}O{sub 4} NPs exhibited photocatalytic activity for degradation of organic dyes such as methylene blue (k = 0.0105475 min{sup −1}), congo red (k = 0.0043240 min{sup −1}), and methyl orange (k = 0.0028930 min{sup −1}), efficiently. The antioxidant activity of Fe{sub 3}O{sub 4} NPs against 1, 1-diphenyl-2-picrylhydrazyl were also evaluated. - Highlights: • We report extracellular phytosynthesis of Fe{sub 3}O{sub 4} nanoparticles using the Andean blackberry leaf. • The synthesized Fe{sub 3}O{sub 4} nanoparticles are spherical and average size is 54.5 ± 24.6 nm. • It showed enhanced photocatalytic activity and weak antioxidant efficacy. • Environmentally benign, non-toxic and cost-effective method is suggested.

  5. Crustal deformation and volcanism at active plate boundaries

    Science.gov (United States)

    Geirsson, Halldor

    Most of Earth's volcanoes are located near active tectonic plate boundaries, where the tectonic plates move relative to each other resulting in deformation. Likewise, subsurface magma movement and pressure changes in magmatic systems can cause measurable deformation of the Earth's surface. The study of the shape of Earth and therefore studies of surface deformation is called geodesy. Modern geodetic techniques allow precise measurements (˜1 mm accuracy) of deformation of tectonic and magmatic systems. Because of the spatial correlation between tectonic boundaries and volcanism, the tectonic and volcanic deformation signals can become intertwined. Thus it is often important to study both tectonic and volcanic deformation processes simultaneously, when one is trying to study one of the systems individually. In this thesis, I present research on crustal deformation and magmatic processes at active plate boundaries. The study areas cover divergent and transform plate boundaries in south Iceland and convergent and transform plate boundaries in Central America, specifically Nicaragua and El Salvador. The study is composed of four main chapters: two of the chapters focus on the magma plumbing system of Hekla volcano, Iceland and the plate boundary in south Iceland; one chapter focuses on shallow controls of explosive volcanism at Telica volcano, Nicaragua; and the fourth chapter focuses on co- and post-seismic deformation from a Mw = 7.3 earthquake which occurred offshore El Salvador in 2012. Hekla volcano is located at the intersection of a transform zone and a rift zone in Iceland and thus is affected by a combination of shear and extensional strains, in addition to co-seismic and co-rifting deformation. The inter-eruptive deformation signal from Hekla is subtle, as observed by a decade (2000-2010) of GPS data in south Iceland. A simultaneous inversion of this data for parameters describing the geometry and source characteristics of the magma chamber at Hekla, and

  6. Neogene stratigraphy and Andean geodynamics of southern Ecuador

    Science.gov (United States)

    Hungerbühler, Dominik; Steinmann, Michael; Winkler, Wilfried; Seward, Diane; Egüez, Arturo; Peterson, Dawn E.; Helg, Urs; Hammer, Cliff

    2002-01-01

    The present paper reviews Tertiary volcanic and sedimentary formations in the Inter-Andean region of southern Ecuador (between 2°S and 4°20'S) in order to develop a geodynamic model of the region. The formations occur in the southern shallow prolongation of the Inter-Andean Valley between the Cordillera Real to the east, and the Cordillera Occidental and Amotape-Tahuín Provinces to the west. One hundred fifty zircon fission-track analyses has established a detailed chronostratigraphy for the sedimentary and volcanic formations and several small intrusions. The Paleogene to early Miocene formations are dominated by intermediate and acidic volcanic and pyroclastic rocks. In addition, relics of Eocene continental sedimentary series have been identified. The Neogene sedimentary series lie unconformably on deformed and eroded metamorphic, sedimentary and volcanic formations. They were deposited in two stages, which are separated by a major unconformity dated at ≈10-9 Ma. (1) During the middle and early late Miocene (≈15-10 Ma) marginal marine deltaic, lagoonal, lacustrine and fluvial environments prevailed, which we group under the heading "Pacific Coastal sequences". They presumably covered a greater surface area in southern Ecuador than their present occurrence in small topographic depressions. We suggest that they were deposited in the shallow marine Cuenca and Loja Embayments. Deposition in a marginal marine environment is also supported by the occurrence of brackish water ostracods and other fauna. (2) Above the regional (angular) unconformity, the coastal facies are overlain by late Miocene (≈9-5 Ma) continental alluvial fan and fluvial facies which are in turn covered by mainly airborne volcanic material. They represent the "Intermontane sequences" of the basins of Cuenca, Girón-Santa Isabel, Nabón, Loja and Malacatos-Vilcabamba. Sedimentologic and stratigraphic results are used to discuss the tectonic setting of Neogene sedimentation in the forearc

  7. Sediment-infill volcanic breccia from the Neoarchean Shimoga greenstone terrane, western Dharwar Craton: Implications on pyroclastic volcanism and sedimentation in an active continental margin

    Science.gov (United States)

    Manikyamba, C.; Saha, Abhishek; Ganguly, Sohini; Santosh, M.; Lingadevaru, M.; Rajanikanta Singh, M.; Subba Rao, D. V.

    2014-12-01

    We report sediment-infill volcanic breccia from the Neoarchean Shimoga greenstone belt of western Dharwar Craton which is associated with rhyolites, chlorite schists and pyroclastic rocks. The pyroclastic rocks of Yalavadahalli area of Shimoga greenstone belt host volcanogenic Pb-Cu-Zn mineralization. The sediment-infill volcanic breccia is clast-supported and comprises angular to sub-angular felsic volcanic clasts embedded in a dolomitic matrix that infilled the spaces in between the framework of volcanic clasts. The volcanic clasts are essentially composed of alkali feldspar and quartz with accessory biotite and opaques. These clasts have geochemical characteristics consistent with that of the associated potassic rhyolites from Daginkatte Formation. The rare earth elements (REE) and high field strength element (HFSE) compositions of the sediment-infill volcanic breccia and associated mafic and felsic volcanic rocks suggest an active continental margin setting for their generation. Origin, transport and deposition of these rhyolitic clasts and their aggregation with infiltrated carbonate sediments may be attributed to pyroclastic volcanism, short distance transportation of felsic volcanic clasts and their deposition in a shallow marine shelf in an active continental margin tectonic setting where the rhyolitic clasts were cemented by carbonate material. This unique rock type, marked by close association of pyroclastic volcanic rocks and shallow marine shelf sediments, suggest shorter distance between the ridge and shelf in the Neoarchean plate tectonic scenario.

  8. The volcanism of the western part of the Los Frailes Meseta (Bolivia): a representative example of the Andean volcanism since the Upper Oligocene; Le volcanisme de la bordure occidentale de la Meseta de Los Frailes (Bolivie): un jalon representatif du volcanisme andin depuis l`Oligocene superieur

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, L. [Nancy-1 Univ., 54 (France); Jimenez, N.

    1996-12-31

    The Los Frailes Meseta (Bolivia) is one of the large tertiary ignimbritic fields of the inner volcanic arc from Central Andes (Central Volcanic Zone. CVZ), in contact zone between the Altiplano to the west and the Eastern Cordillera to the east. Field observations and mineralogical and geochemical studies (major and trace elements) lead to distinguish two types of volcanism in the western border to the Meseta. During the Middle Miocene and Pliocene, the volcanic activity can be subdivided into three pyroclastic emission cycles, the Larco, Coroma and Pliocene ignimbrites, the first two being separated by the Quechua 2 orogeny. All these ignimbrites are very similar and correspond to peraluminous rhyolites to rhyodacites. In the studies area, the Coroma cycle is the only one where an ignimbrite-less evolved resurgent dome association can be observed. Beside these ignimbrites, isolated small lava flows and domes overlay and/or intrude all the other formations. They are meta-aluminous lavas with a shoshonitic affinity. A quaternary age can be attributed to his second volcanism. These two volcanic types are well-known in the CVZ and are related to the different deformation stages, either compressional or extensional, which occur alternately in the Cordillera since 26 Ma. (authors). 61 refs., 12 figs., 3 tabs.

  9. Study of Volcanic Activity at Different Time Scales Using Hypertemporal Land Surface Temperature Data

    NARCIS (Netherlands)

    Pavlidou, Efthymia; Hecker, Chris; van der Werff, Harald; van der Meijder, Mark

    2017-01-01

    We apply a method for detecting subtle spatiotemporal signal fluctuations to monitor volcanic activity. Whereas midwave infrared data are commonly used for volcanic hot spot detection, our approach utilizes hypertemporal longwave infrared-based land surface temperature (LST) data. Using LST data of

  10. The Role of Volcanic Activity in Climate and Global Change

    KAUST Repository

    Stenchikov, Georgiy L.

    2015-01-01

    . The recent interest in dynamic, microphysical, chemical, and climate impacts of volcanic eruptions is also excited by the fact that these impacts provide a natural analogue for climate geoengineering schemes involving deliberate development of an artificial

  11. Monitoring of Volcanic Activity by Sub-mm Geodetic Analyses

    Science.gov (United States)

    Miura, S.; Mare, Y.; Ichiki, M.; Demachi, T.; Tachibana, K.; Nishimura, T.

    2017-12-01

    Volcanic earthquakes have been occurring beneath Zao volcano in northern Honshu, Japan since 2013, following the increase of deep low frequency earthquakes from 2012. On account of a burst of seismicity initiated in April 2015, the JMA announced a warning of eruption, however, the seismicity gradually decreased for the next two months and the warning was canceled in June. In the same time period, minor expansive deformation was observed by GNSS. Small earthquakes are still occurring, and low-freq. earthquakes (LPE) occur sometimes accompanied by static tilt changes. In this study, we try to extract the sub-mm displacements from the LPE waveforms observed by broadband seismometers (BBS) and utilize them for geodetic inversion to monitor volcanic activities. Thun et al. (2015, 2016) devised an efficient method using a running median filter (RMF) to remove LP noises, which contaminate displacement waveforms. They demonstrated the reproducibility of the waveforms corresponding to the experimentally given sub-mm displacements in the laboratory. They also apply the method to the field LPE data obtained from several volcanoes to show static displacements. The procedure is outlined as follows: (1) Unfiltered removal of the instrument response, (2) LP noise estimate by LPF with a corner frequency of 5/M, where M (seconds) is the time window of the RMF and should be at least three times the length of the rise time. (3) Subtract the noise estimated from step (2). (4) Integrate to obtain displacement waveforms. We apply the method to the BBS waveform at a distance of about 1.5 km ESE from the summit crater of Zao Volcano associated with a LPE on April 1, 2017. Assuming the time window M as 300 seconds, we successfully obtained the displacement history: taking the rise time of about 2 minutes, the site was gradually uplifted with the amount of about 50-60 µm and then subsided with HF displacements in the next 2 minutes resulting about 20-30 µm static upheaval. Comparing the

  12. Experimental study on the effect of calcination on the volcanic ash activity of diatomite

    Science.gov (United States)

    Xiao, Liguang; Pang, Bo

    2017-09-01

    The volcanic ash activity of diatomite was studied under the conditions of aerobic calcination and vacuum calcination by the combined water rate method, it was characterized by XRD, BET and SEM. The results showed that the volcanic ash activity of diatomite under vacuum conditions was higher than that of aerobic calcination, 600°C vacuum calcination 2h, the combined water rate of diatomite-Ca(OH)2-H2O system was increased from 6.24% to 71.43%, the volcanic ash activity reached the maximum value, the specific surface

  13. Rapid response of a hydrologic system to volcanic activity: Masaya volcano, Nicaragua

    Science.gov (United States)

    Pearson, S.C.P.; Connor, C.B.; Sanford, W.E.

    2008-01-01

    Hydrologic systems change in response to volcanic activity, and in turn may be sensitive indicators of volcanic activity. Here we investigate the coupled nature of magmatic and hydrologic systems using continuous multichannel time series of soil temperature collected on the flanks of Masaya volcano, Nicaragua, one of the most active volcanoes in Central America. The soil temperatures were measured in a low-temperature fumarole field located 3.5 km down the flanks of the volcano. Analysis of these time series reveals that they respond extremely rapidly, on a time scale of minutes, to changes in volcanic activity also manifested at the summit vent. These rapid temperature changes are caused by increased flow of water vapor through flank fumaroles during volcanism. The soil temperature response, ~5 °C, is repetitive and complex, with as many as 13 pulses during a single volcanic episode. Analysis of the frequency spectrum of these temperature time series shows that these anomalies are characterized by broad frequency content during volcanic activity. They are thus easily distinguished from seasonal trends, diurnal variations, or individual rainfall events, which triggered rapid transient increases in temperature during 5% of events. We suggest that the mechanism responsible for the distinctive temperature signals is rapid change in pore pressure in response to magmatism, a response that can be enhanced by meteoric water infiltration. Monitoring of distal fumaroles can therefore provide insight into coupled volcanic-hydrologic-meteorologic systems, and has potential as an inexpensive monitoring tool.

  14. Intra-arc Seismicity: Geometry and Kinematic Constraints of Active Faulting along Northern Liquiñe-Ofqui and Andean Transverse Fault Systems [38º and 40ºS, Southern Andes

    Science.gov (United States)

    Sielfeld, G.; Lange, D.; Cembrano, J. M.

    2017-12-01

    Intra-arc crustal seismicity documents the schizosphere tectonic state along active magmatic arcs. At oblique-convergent margins, a significant portion of bulk transpressional deformation is accommodated in intra-arc regions, as a consequence of stress and strain partitioning. Simultaneously, crustal fluid migration mechanisms may be controlled by the geometry and kinematics of crustal high strain domains. In such domains shallow earthquakes have been associated with either margin-parallel strike-slip faults or to volcano-tectonic activity. However, very little is known on the nature and kinematics of Southern Andes intra-arc crustal seismicity and its relation with crustal faults. Here we present results of a passive seismicity study based on 16 months of data collected from 33 seismometers deployed along the intra-arc region of Southern Andes between 38˚S and 40˚S. This region is characterized by a long-lived interplay among margin-parallel strike-slip faults (Liquiñe-Ofqui Fault System, LOFS), second order Andean-transverse-faults (ATF), volcanism and hydrothermal activity. Seismic signals recorded by our network document small magnitude (0.2P and 2,796 S phase arrival times have been located with NonLinLoc. First arrival polarities and amplitude ratios of well-constrained events, were used for focal mechanism inversion. Local seismicity occurs at shallow levels down to depth of ca. 16 km, associated either with stratovolcanoes or to master, N10˚E, and subsidiary, NE to ENE, striking branches of the LOFS. Strike-slip focal mechanisms are consistent with the long-term kinematics documented by field structural-geology studies. Unexpected, well-defined NW-SE elongated clusters are also reported. In particular, a 72-hour-long, N60˚W-oriented seismicity swarm took place at Caburgua Lake area, describing a ca. 36x12x1km3 faulting crustal volume. Results imply a unique snapshot on shallow crustal tectonics, contributing to the understanding of faulting processes

  15. 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.

  16. Learning about hydrothermal volcanic activity by modeling induced geophysical changes

    Science.gov (United States)

    Currenti, Gilda M.; Napoli, Rosalba

    2017-05-01

    Motivated by ongoing efforts to understand the nature and the energy potential of geothermal resources, we devise a coupled numerical model (hydrological, thermal, mechanical), which may help in the characterization and monitoring of hydrothermal systems through computational experiments. Hydrothermal areas in volcanic regions arise from a unique combination of geological and hydrological features which regulate the movement of fluids in the vicinity of magmatic sources capable of generating large quantities of steam and hot water. Numerical simulations help in understanding and characterizing rock-fluid interaction processes and the geophysical observations associated with them. Our aim is the quantification of the response of different geophysical observables (i.e. deformation, gravity and magnetic field) to hydrothermal activity on the basis of a sound geological framework (e.g. distribution and pathways of the flows, the presence of fractured zones, caprock). A detailed comprehension and quantification of the evolution and dynamics of the geothermal systems and the definition of their internal state through a geophysical modeling approach are essential to identify the key parameters for which the geothermal system may fulfill the requirements to be exploited as a source of energy. For the sake of illustration only, the numerical computations are focused on a conceptual model of the hydrothermal system of Vulcano Island by simulating a generic 1-year unrest and estimating different geophysical changes. We solved (i) the mass and energy balance equations of flow in porous media for temperature, pressure and density changes, (ii) the elastostatic equation for the deformation field and (iii) the Poisson’s equations for gravity and magnetic potential fields. Under the model assumptions, a generic unrest of 1-year engenders on the ground surface low amplitude changes in the investigated geophysical observables, that are, however, above the accuracies of the modern

  17. The Lanzarote Geodynamic Laboratory: new capabilities for monitoring of volcanic activity at Canary Islands

    Science.gov (United States)

    Arnoso, J.; Vélez, E. J.; Soler, V.; Montesinos, F. G.; Benavent, M.

    2012-04-01

    The volcanic island of Lanzarote is located at the northeastern end of the Canary Islands. Together with Fuerteventura Island, Lanzarote constitutes the emergent part of the East Canary Ridge, which presents a NNE-SSW volcanic alignment. Last eruptive events took place in 1824 and during the period 1730-1736, which is the largest to occur in the archipelago and throw out about 1.3 km3 of volcanic materials. The Lanzarote Geodynamic Laboratory (LGL) was created in 1986 with the idea of making Lanzarote as a natural laboratory to carry out studies in order to acquire more knowledge about its origin, present status and evolution (Vieira et al., 1991; 2006). The LGL has a multidisciplinary scientific purpose and, among others, various objectives are devoted to investigate mass distribution in the Earth system and surface displacements associated to volcanic and/or seismic activity in the island. The influence of LGL is extended throughout the whole geographical area of Lanzarote, including small islands located at the north. The laboratory has 3 observing modules distributed along the island according to its infrastructure and scientific objectives, where more than 70 sensors are recording continuously gravity variations, ground deformations, sea level, seismic activity, meteorological parameters, etc. All these observations are supplemented by periodic measurement of geodetic and geophysical networks that allow us to make studies at local, insular and regional scales. The application of geodetic and geophysical techniques to identify geodynamic signals related to volcanic processes is then a permanent research activity of the laboratory. Nowadays, this fact becomes more interesting due to the ongoing volcanic eruption that is taking place in other island of the Canary Archipelago, El Hierro, since past July 2011. That is, the multidisciplinary research carry on up to now at the LGL allow us to apply multiparameter observations of different kinds of volcanic

  18. 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.

  19. Learning about Hydrothermal Volcanic Activity by Modeling Induced Geophysical Changes

    Directory of Open Access Journals (Sweden)

    Gilda M. Currenti

    2017-05-01

    Full Text Available Motivated by ongoing efforts to understand the nature and the energy potential of geothermal resources, we devise a coupled numerical model (hydrological, thermal, mechanical, which may help in the characterization and monitoring of hydrothermal systems through computational experiments. Hydrothermal areas in volcanic regions arise from a unique combination of geological and hydrological features which regulate the movement of fluids in the vicinity of magmatic sources capable of generating large quantities of steam and hot water. Numerical simulations help in understanding and characterizing rock-fluid interaction processes and the geophysical observations associated with them. Our aim is the quantification of the response of different geophysical observables (i.e., deformation, gravity, and magnetic fields to hydrothermal activity on the basis of a sound geological framework (e.g., distribution and pathways of the flows, the presence of fractured zones, caprock. A detailed comprehension and quantification of the evolution and dynamics of the geothermal systems and the definition of their internal state through a geophysical modeling approach are essential to identify the key parameters for which the geothermal system may fulfill the requirements to be exploited as a source of energy. For the sake of illustration only, the numerical computations are focused on a conceptual model of the hydrothermal system of Vulcano Island by simulating a generic 1-year unrest and estimating different geophysical changes. We solved (i the mass and energy balance equations of flow in porous media for temperature, pressure and density changes, (ii the elastostatic equation for the deformation field and (iii the Poisson's equations for gravity and magnetic potential fields. Under the model assumptions, a generic unrest of 1-year engenders on the ground surface low amplitude changes in the investigated geophysical observables, that, being above the accuracies of

  20. Recent progress in volcanism studies: Site characterization activities for the Yucca Mountain site characterization project

    International Nuclear Information System (INIS)

    Crowe, B.M.; Valentine, G.; Morley, R.; Perry, F.V.

    1992-01-01

    Significant progress has been made on volcanism studies over the past calendar year. There are a number of major highlights from this work. Geochronology data have been obtained for the Lathrop Wells center using a range of isotopic, radiogenic, and age-calibrated methods. Initial work is encouraging but still insufficient to resolve the age of the center with confidence. Geologic mapping of the Sleeping Butte volcanic centers was completed and a report issued on the geology and chronology data. Twenty shallow trenches have been constructed in volcanic units of the Lathrop Wells volcanic center. Results of detailed studies of the trenches support a polycyclic eruptive history. New soil data from the trenches continue to support a late Pleistocene or Holocene age for many of the volcanic units at the center. Geochemical data (trace element and isotopic analysis) show that the volcanic units of the Lathrop Wells center cannot be related to one another by fractional crystallization of a single magma batch, supporting a polycyclic model of volcanism. Structural models using existing data are used to evaluate the probability of magmatic disruption of a potential repository. Several permissive models have been developed but none lead to significant differences in calculating the disruption ratio. Work was initiated on the eruptive and subsurface effects of magmatic activity on a repository. (author)

  1. [Chemical characterization and quantification of fructooligosaccharides, phenolic compounds and antiradical activity of Andean roots and tubers grown in Northwest of Argentina].

    Science.gov (United States)

    Jiménez, María Eugenia; Sammán, Norma

    2014-06-01

    There is great interest in consuming foods that can provide the nutrients for a good nutrition and other health beneficial compounds. The aim of this work was to determine the chemical composition of native foods of the Andean region and to quantify some functional com-ponents. Proximal composition, vitamin C, total phenolic compounds, antiradical activity (DPPH) in peel and pulp, dietary fiber soluble and insoluble, fructooligosaccharides (FOS), total and resistant starch (in tubers and raw roots, boiled and boiled and stored) of 6 varieties of Oca (Oxalis tuberosa), 4 clones of manioc (Manihot esculenta Crantz) and yacon (Smallanthus sonchifolius were determined. The results showed greater amount of bioactive compounds and antiradical activity in the skin of these products. The highest content was found in the oca peel. In all cases, the content of insoluble fiber was greater than the soluble. The manioc had higher total starch than Andean roots and tubers. The boiling process decreased the resistant starch content of ocas and maniocs, but when these are stored for 48 h at 5 ° C, the resistant starch content increased. The FOS content of the ocas was similar for all varieties (7%). The main component of yacon carbohydrates were FOS (8.89%). The maniocs did not contain FOS. It can be concluded that the roots and tubers studied, in addition to provide nutrients, contain functional compounds that confer additional helpful value for preventing no communicable diseases.

  2. K-Ar chronological study of the quaternary volcanic activity in Shin-etsu Highland

    International Nuclear Information System (INIS)

    Kaneko, Takayuki; Shimizu, Satoshi; Itaya, Tetsumaru.

    1989-01-01

    In order to clarify the temporal and spatial patterns in arc volcanism, 55 K-Ar ages of volcanic rocks from 17 volcanoes in Shin-etsu Highland, central Japan were determined. In addition, life spans, volume of erupted materials and eruption rates of each volcano were estimated. Graphical analysis demonstrates that volume of ejecta varies proportionately with both life span and eruption rate, and that there is no significant correlation between eruption rate and distance from the volcanic front. The life span of each volcano in this Highland is less than 0.6 m.y. In the central Shiga and southern Asama area, the volcanism started at 1 Ma and is still active. However the former had a peak in the activity at around 0.5 Ma, while the latter is apparently most intense at present. Northern Kenashi area has the volcanism without peak in 1.7 - 0.2 Ma, though the activity within a volcanic cluster or chain in central Japan lasts generally for 1 m.y. or less with a peak. (author)

  3. Forests of the tropical eastern Andean flank during the middle Pleistocene

    NARCIS (Netherlands)

    Cárdenas, M.L.; Gosling, W.D.; Pennington, R.T.; Poole, I.; Sherlock, S.C.; Mothes, P.

    2014-01-01

    Inter-bedded volcanic and organic sediments from Erazo (Ecuador) indicate the presence of four different forest assemblages on the eastern Andean flank during the middle Pleistocene. Radiometric dates (40Ar-39Ar) obtained from the volcanic ash indicate that deposition occurred between 620,000 and

  4. Geologic evolution of the Jemez Mountains and their potential for future volcanic activity

    International Nuclear Information System (INIS)

    Burton, B.W.

    1982-01-01

    Geophysical and geochemical data and the geologic history of the Rio Grande rift and the vicinity of the Jemez Mountains are summarized to determine the probability of future volcanic activity in the Los Alamos, New Mexico area. The apparent cyclic nature of volcanism in the Jemez Mountains may be related to intermittent thermal inputs into the volcanic system beneath the region. The Jemez lineament, an alignment of late Cenozoic volcanic centers that crosses the rift near Los Alamos, has played an important role in the volcanic evolution of the Jemez Mountains. Geophysical data suggest that there is no active shallow magma body beneath the Valles caldera, though magma probably exists at about 15 km beneath this portion of the rift. The rate of volcanism in the Jemez Mountains during the last 10 million years has been 5 x 10 -9 /km 2 /y. Lava or ash flows overriding Laboratory radioactive waste disposal sites would have little potential to release radionuclides to the environment. The probability of a new volcano intruding close enough to a radioactive waste disposal site to effect radionuclide release is 2 x 10 -7 /y

  5. Soil radon concentration and volcanic activity of Mt. Etna before and after the 2002 eruption

    International Nuclear Information System (INIS)

    Imme, G.; La Delfa, S.; Lo Nigro, S.; Morelli, D.; Patane, G.

    2006-01-01

    Soil radon investigation, using a continuous measurement device, has been performed on Mt. Etna in order to observe possible anomalies due to seismic and/or volcanic activity. In October 2002 an eruptive event occurred. Measurements, performed on the NE flank, have shown a possible correlation between eruptive activity of the volcano and soil radon concentration anomaly. The study of the seismic activity recorded in the same flank has, also, allowed to characterize the volcano dynamics and to correlate it with the variations of radon. The obtained results seem to indicate a possible dependence on volcanic activity of the radon concentration

  6. Volcanic ash activates the NLRP3 inflammasome in murine and human macrophages

    Science.gov (United States)

    Damby, David; Horwell, Claire J.; Baxter, Peter J.; Kueppers, Ulrich; Schnurr, Max; Dingwell, Donald B.; Duewell, Peter

    2018-01-01

    Volcanic ash is a heterogeneous mineral dust that is typically composed of a mixture of amorphous (glass) and crystalline (mineral) fragments. It commonly contains an abundance of the crystalline silica (SiO2) polymorph cristobalite. Inhalation of crystalline silica can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that plays a critical role in driving inflammatory immune responses. Ingested material results in the assembly of NLRP3, ASC, and caspase-1 with subsequent secretion of the interleukin-1 family cytokine IL-1β. Previous toxicology work suggests that cristobalite-bearing volcanic ash is minimally reactive, calling into question the reactivity of volcanically derived crystalline silica, in general. In this study, we target the NLRP3 inflammasome as a crystalline silica responsive element to clarify volcanic cristobalite reactivity. We expose immortalized bone marrow-derived macrophages of genetically engineered mice and primary human peripheral blood mononuclear cells (PBMCs) to ash from the Soufrière Hills volcano as well as representative, pure-phase samples of its primary componentry (volcanic glass, feldspar, cristobalite) and measure NLRP3 inflammasome activation. We demonstrate that respirable Soufrière Hills volcanic ash induces the activation of caspase-1 with subsequent release of mature IL-1β in a NLRP3 inflammasome-dependent manner. Macrophages deficient in NLRP3 inflammasome components are incapable of secreting IL-1β in response to volcanic ash ingestion. Cellular uptake induces lysosomal destabilization involving cysteine proteases. Furthermore, the response involves activation of mitochondrial stress pathways leading to the generation of reactive oxygen species. Considering ash componentry, cristobalite is the most reactive pure-phase with other components inducing only low-level IL-1β secretion. Inflammasome activation mediated by inhaled ash and its potential relevance in chronic pulmonary

  7. 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.

  8. Characterization of Io's volcanic activity by infrared polarimetry

    International Nuclear Information System (INIS)

    Goguen, J.D.; Sinton, W.M.

    1985-01-01

    The thermal emission from Io's volcanic hot spots is linearly polarized.Infrared measurements at 4.76 micrometers show disk-integrated polarization as large as 1.6 percent. The degree and position angle of linear polarization vary with Io's rotation in a manner characteristic of emission from a small number of hot spots. A model incorporating three hot spots best fits the data. The largest of these hot spots lies to the northeast of Loki Patera, as mapped from Voyager, and the other spot on the trailing hemisphere is near Ra Patera. The hot spot on the leading hemisphere corresponds to no named feature on the Voyager maps. The value determined for the index of refraction of the emitting surface is a lower bound; it is similar to that of terrestrial basalts and is somewhat less than that of sulfur. 25 references

  9. Magmatic activity stages of the El'brus volcanic center (Great Caucasus): isotope geochronological data

    International Nuclear Information System (INIS)

    Chernyshev, I.V.; Lebedev, V.A.; Bubnov, S.N.; Arakelyants, M.M.; Gol'tsman, Yu.V.

    2001-01-01

    The age of volcanites in the Elbrus volcanic center was determined by the methods of K-Ar- and Rb-Sr-dating to ascertain stages of magmatic activity in the area. The data obtained suggest existence of at least two stages of magmatic activity: Middle Neopleistocene (225-180 thous. years) and Late Neopleistocene-Holocene ( [ru

  10. The research of modern He discharge in volcanic and tectonically active areas of China's continent

    International Nuclear Information System (INIS)

    Shangguan, Z.G.

    1999-01-01

    The realising features of modern helium in volcanic and tectonically active areas of China's continent are here discussed, presenting that the current escaped He in volcanic areas are mainly the mantle-derived He. The 3 He/ 4 He ratios of crustal gases in Eastern China are relatively higher than those gases in Middle-Western China. The author considers difficult to interpret this phenomenon by means of the differences of tectonic activity in those areas: it may be related to the variation of crustal thickness of China's continent from East to West

  11. Late Cenozoic Samtskhe-Javakheti Volcanic Highland, Georgia:The Result of Mantle Plumes Activity

    Science.gov (United States)

    Okrostsvaridze, Avtandil

    2017-04-01

    Late Cenozoic Samtskhe-Javakheti continental volcanic highland (1500-2500 m a.s.l) is located in the SW part of the Lesser Caucasus. In Georgia the highland occupies more than 4500 km2, however its large part spreads towards the South over the territories of Turkey and Armenia. One can point out three stages of magmatic activity in this volcanic highland: 1. Early Pliocene activity (5.2-2.8 Ma; zircons U-Pb age) - when a large part of the highland was built up. It is formed from volcanic lava-breccias of andesite-dacitic composition, pyroclastic rocks and andesite-basalt lava flow. The evidences of this structure are: a large volume of volcanic material (>1500 km3); big thickness (700-1100 m in average), large-scale of lava flows (length 35 km, width 2.5-3.5 km, thickness 30-80 m), big thickness of volcanic ash horizons (300 cm at some places) and big size of volcanic breccias (diameter >1 m). Based on this data we assume that a source of this structure was a supervolcano (Okrostsvaridze et al., 2016); 2. Early Pleistocene activity (2.4 -1.6 Ma; zircons U-Pb age) - when continental flood basalts of 100-300 m thickness were formed. The flow is fully crystalline, coarse-grained, which mainly consist of olivine and basic labradorite. There 143Nd/144Nd parameter varies in the range of +0.41703 - +0.52304, and 87Sr/88Sr - from 0.7034 to 0.7039; 3. Late Pleistocene activity (0.35-0.021 Ma; zircons U-Pb age) - when intraplate Abul-Samsari linear volcanic ridge of andesite composition was formed stretching to the S-N direction for 40 km with the 8-12 km width and contains more than 20 volcanic edifices. To the South of the Abul-Samsari ridge the oldest (0.35-0.30 Ma; zircons U-Pb age) volcano Didi Abuli (3305 m a.s.l.) is located. To the North ages of volcano edifices gradually increase. Farther North the youngest volcano Tavkvetili (0.021-0. 030 Ma) is located (2583 m a.s.l.). One can see from this description that the Abul-Samsari ridge has all signs characterizing

  12. Volcanic features of Io

    International Nuclear Information System (INIS)

    Carr, M.H.; Masursky, H.; Strom, R.G.; Terrile, R.J.

    1979-01-01

    The volcanic features of Io as detected during the Voyager mission are discussed. The volcanic activity is apparently higher than on any other body in the Solar System. Its volcanic landforms are compared with features on Earth to indicate the type of volcanism present on Io. (U.K.)

  13. The Importance of Differing Types of Io Volcanic Activity for the Jupiter Magnetosphere

    Science.gov (United States)

    Howell, R. R.

    2016-12-01

    The Jupiter magnetosphere is populated largely by sulfur and oxygen ultimately derived from the volcanoes on Io and correlations have been detected between changes in volcanic activity and the magnetosphere. However different types of volcanic activity on Io vary widely in the amount and composition of the gasses they release. For example while Loki is often the brightest volcanic hotspot in the infrared (and therefore most easily monitored from earth) it appears to release a comparatively small amount of gas compared to Prometheus type plumes and the giant plumes such as Pele. The dominant volatile released at most sites is sulfur dioxide but giant plumes such as Pele appear to contain significantly fractions of S2 gas. The amounts and type of dust produced may also differ. Finally, the way material is buffered in Io's surface and atmosphere before escaping to the magnetosphere is also uncertain. A better understanding of the connection between volcanic activity and the magnetosphere will require studying not just correlations between broad measures of activity but rather specific indices of different types of activity. Observations of possible storage buffers such as the atmosphere, as are now becoming possible with ALMA, will also be essential.

  14. Modeling of hydrothermal circulation applied to active volcanic areas. The case of Vulcano (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Todesco, M. [Dip. Scienze della Terra, Posa (Italy)

    1995-03-01

    Modeling of fluid and heat flows through porous media has been diffusely applied up to date to the study of geothermal reservoirs. Much less has been done to apply the same methodology to the study of active volcanoes and of the associated volcanic hazard. Hydrothermal systems provide direct information on dormant eruptive centers and significant insights on their state of activity and current evolution. For this reason, the evaluation of volcanic hazard is also based on monitoring of hydrothermal activity. Such monitoring, however, provides measurements of surface parameters, such as fluid temperature or composition, that often are only representative of the shallower portion of the system. The interpretation of these data in terms of global functioning of the hydrothermal circulation can therefore be highly misleading. Numerical modeling of hydrothermal activity provides a physical approach to the description of fluid circulation and can contribute to its understanding and to the interpretation of monitoring data. In this work, the TOUGH2 simulator has been applied to study the hydrothermal activity at Vulcano (Italy). Simulations involved an axisymmetric domain heated from below, and focused on the effects of permeability distribution and carbon dioxide. Results are consistent with the present knowledge of the volcanic system and suggest that permeability distribution plays a major role in the evolution of fluid circulation. This parameter should be considered in the interpretation of monitoring data and in the evaluation of volcanic hazard at Vulcano.

  15. Search for possible relationship between volcanic ash particles and thunderstorm lightning activity

    Science.gov (United States)

    Várai, A.; Vincze, M.; Lichtenberger, J.; Jánosi, I. M.

    2011-12-01

    Explosive volcanic eruptions that eject columns of ash from the crater often generate lightning discharges strong enough to be remotely located by very low frequency radio waves. A fraction of volcanic ash particles can stay and disperse long enough to have an effect on weather phenomena days later such as thunderstorms and lightnings. In this work we report on lightning activity analysis over Europe following two recent series of volcanic eruptions in order to identify possible correlations between ash release and subsequent thunderstorm flash frequency. Our attempts gave negative results which can be related to the fact that we have limited information on local atmospheric variables of high enough resolution, however lightning frequency is apparently determined by very local circumstances.

  16. Search for possible relationship between volcanic ash particles and thunderstorm lightning activity

    International Nuclear Information System (INIS)

    Várai, A; Vincze, M; Jánosi, I M; Lichtenberger, J

    2011-01-01

    Explosive volcanic eruptions that eject columns of ash from the crater often generate lightning discharges strong enough to be remotely located by very low frequency radio waves. A fraction of volcanic ash particles can stay and disperse long enough to have an effect on weather phenomena days later such as thunderstorms and lightnings. In this work we report on lightning activity analysis over Europe following two recent series of volcanic eruptions in order to identify possible correlations between ash release and subsequent thunderstorm flash frequency. Our attempts gave negative results which can be related to the fact that we have limited information on local atmospheric variables of high enough resolution, however lightning frequency is apparently determined by very local circumstances.

  17. Multiple episodes of hydrothermal activity and epithermal mineralization in the southwestern Nevada volcanic field and their relations to magmatic activity, volcanism and regional extension

    International Nuclear Information System (INIS)

    Weiss, S.I.; Noble, D.C.; Jackson, M.C.

    1994-01-01

    Volcanic rocks of middle Miocene age and underlying pre-Mesozoic sedimentary rocks host widely distributed zones of hydrothermal alteration and epithermal precious metal, fluorite and mercury deposits within and peripheral to major volcanic and intrusive centers of the southwestern Nevada volcanic field (SWNVF) in southern Nevada, near the southwestern margin of the Great Basin of the western United States. Radiometric ages indicate that episodes of hydrothermal activity mainly coincided with and closely followed major magmatic pulses during the development of the field and together spanned more than 4.5 m.y. Rocks of the SWNVF consist largely of rhyolitic ash-flow sheets and intercalated silicic lava domes, flows and near-vent pyroclastic deposits erupted between 15.2 and 10 Ma from vent areas in the vicinity of the Timber Mountain calderas, and between about 9.5 and 7 Ma from the outlying Black Mountain and Stonewall Mountain centers. Three magmatic stages can be recognized: the main magmatic stage, Mountain magmatic stage (11.7 to 10.0 Ma), and the late magmatic stage (9.4 to 7.5 Ma)

  18. Late Pleistocene and Holocene activity of the Atacazo-Ninahuilca Volcanic Complex (Ecuador)

    NARCIS (Netherlands)

    Hidalgo, Silvana; Monzier, Michel; Almeida, Eduardo; Chazot, Gilles; Eissen, Jean-Philippe; van der Plicht, Johannes; Hall, Minard L.

    2008-01-01

    The Atacazo-Ninahuilca Volcanic Complex (ANVC) is located in the Western Cordillera of Ecuador, 10 km southwest of Quito. At least six periods of Pleistocene to Holocene activity (N1 to N6) have been preserved in the geologic record as tephra fallouts and pyroclastic flow deposits. New field data,

  19. Impact of potato cultivation and cattle farming on physicochemical parameters and enzymatic activities of Neotropical high Andean Páramo ecosystem soils.

    Science.gov (United States)

    Avellaneda-Torres, Lizeth Manuela; León Sicard, Tomás Enrique; Torres Rojas, Esperanza

    2018-08-01

    The Andean Páramos are high mountain ecosystems whose soils are essential for the management of South American water resources, but research on anthropic impacts to these soils is currently minimal and insufficient. The objective of this study was to evaluate the impacts of potato (Solanum tuberosum) cultivation and livestock on the physicochemical parameters and enzymatic activities that determine the soil quality of the Neotropical high Andean Páramo ecosystem in the Nevados National Natural Park (Nevados NNP) in Colombia. It was hypothesised that sites with potato crops and livestock farming would exhibit significant changes in soil physicochemical parameters and enzymatic activities compared with Páramo sites that have been conserved without agriculture. Samples were collected from soils under potato cultivation, livestock and Páramo (subject to the lowest degree of human intervention possible), on three farms in the El Bosque District at three different altitudes (Buenos Aires, El Edén and La Secreta) during two seasons (dry and rainy). The results showed that none of the physical parameters under study presented statistically significant differences due to the type of use (livestock, potato crop or Páramo), season of sampling (dry or rainy season) or altitude (different farms). The chemical parameters that statistically significantly differed due to land use were organic carbon, cation exchange capacity, calcium, potassium, and ammonium and those that showed statistically significant differences associated with the sampling timing were organic carbon, nitrogen, cation exchange capacity, total carbon, C/N and nitrate. Additionally, there were differences in organic carbon due to the altitude of the farms. With respect to enzymatic activities, those of β-glucosidase, phosphodiesterase and urease significantly decreased in soils under potato cultivation and livestock relative to those of Páramo, but those of acid phosphatase and protease increased

  20. Ocatin. A novel tuber storage protein from the andean tuber crop oca with antibacterial and antifungal activities.

    Science.gov (United States)

    Flores, Teresita; Alape-Girón, Alberto; Flores-Díaz, Marietta; Flores, Hector E

    2002-04-01

    The most abundant soluble tuber protein from the Andean crop oca (Oxalis tuberosa Mol.), named ocatin, has been purified and characterized. Ocatin accounts for 40% to 60% of the total soluble oca tuber proteins, has an apparent molecular mass of 18 kD and an isoelectric point of 4.8. This protein appears to be found only in tubers and is accumulated only within the cells of the pith and peridermis layers (peel) of the tuber as it develops. Ocatin inhibits the growth of several phytopathogenic bacteria (Agrobacterium tumefaciens, Agrobacterium radiobacter, Serratia marcescens, and Pseudomonas aureofaciens) and fungi (Phytophthora cinnamomi, Fusarium oxysporum, Rhizoctonia solani, and Nectria hematococcus). Ocatin displays substantial amino acid sequence similarity with a widely distributed group of intracellular pathogenesis-related proteins with a hitherto unknown biological function. Our results showed that ocatin serves as a storage protein, has antimicrobial properties, and belongs to the Betv 1/PR-10/MLP protein family. Our findings suggest that an ancient scaffolding protein was recruited in the oca tuber to serve a storage function and that proteins from the Betv 1/PR-10/MLP family might play a role in natural resistance to pathogens.

  1. Ocatin. A Novel Tuber Storage Protein from the Andean Tuber Crop Oca with Antibacterial and Antifungal Activities1

    Science.gov (United States)

    Flores, Teresita; Alape-Girón, Alberto; Flores-Díaz, Marietta; Flores, Hector E.

    2002-01-01

    The most abundant soluble tuber protein from the Andean crop oca (Oxalis tuberosa Mol.), named ocatin, has been purified and characterized. Ocatin accounts for 40% to 60% of the total soluble oca tuber proteins, has an apparent molecular mass of 18 kD and an isoelectric point of 4.8. This protein appears to be found only in tubers and is accumulated only within the cells of the pith and peridermis layers (peel) of the tuber as it develops. Ocatin inhibits the growth of several phytopathogenic bacteria (Agrobacterium tumefaciens, Agrobacterium radiobacter, Serratia marcescens, and Pseudomonas aureofaciens) and fungi (Phytophthora cinnamomi, Fusarium oxysporum, Rhizoctonia solani, and Nectria hematococcus). Ocatin displays substantial amino acid sequence similarity with a widely distributed group of intracellular pathogenesis-related proteins with a hitherto unknown biological function. Our results showed that ocatin serves as a storage protein, has antimicrobial properties, and belongs to the Betv 1/PR-10/MLP protein family. Our findings suggest that an ancient scaffolding protein was recruited in the oca tuber to serve a storage function and that proteins from the Betv 1/PR-10/MLP family might play a role in natural resistance to pathogens. PMID:11950978

  2. Desarrollo de herramientas de gestión socio-ambiental para cuencas andinas con actividades mineras = Development of socio-environmental management tools for Andean basins with mining activities

    OpenAIRE

    Pérez Foguet, Agustí; Yacoub López, Cristina; Miralles Esteban, Núria

    2013-01-01

    We present an analysis of three socio-environmental management tools developed and applied to an example of Andean basin with mining activities of significant importance. Socio-environmental conflicts related to mining activities are of increasing interest in the region. Most of them include water quality or quantity issues as a central part of the disputes. On the other hand, environmental regulations are changing from a paradigm focused on pollution control to a paradigm based on the health...

  3. 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.

  4. First volcanic CO2 budget estimate for three actively degassing volcanoes in the Central American Volcanic Arc

    Science.gov (United States)

    Robidoux, Philippe; Aiuppa, Alessandro; Conde, Vladimir; Galle, Bo; Giudice, Gaetano; Avard, Geoffroy; Muñoz, Angélica

    2014-05-01

    CO2 is a key chemical tracer for exploring volcanic degassing mechanisms of basaltic magmatic systems (1). The rate of CO2 release from sub-aerial volcanism is monitored via studies on volcanic plumes and fumaroles, but information is still sparse and incomplete for many regions of the globe, including the majority of the volcanoes in the Central American Volcanic Arc (2). Here, we use a combination of remote sensing techniques and in-situ measurements of volcanic gas plumes to provide a first estimate of the CO2 output from three degassing volcanoes in Central America: Turrialba, in Costa Rica, and Telica and San Cristobal, in Nicaragua. During a field campaign in March-April 2013, we obtained (for the three volcanoes) a simultaneous record of SO2 fluxes (from the NOVAC network (3)) and CO2 vs. SO2 concentrations in the near-vent plumes (obtained via a temporary installed fully-automated Multi-GAS instrument (4)). The Multi-GAS time-series allowed to calculate the plume CO2/SO2 ratios for different intervals of time, showing relatively stable gas compositions. Distinct CO2 - SO2 - H2O proportions were observed at the three volcanoes, but still within the range of volcanic arc gas (5). The CO2/SO2 ratios were then multiplied by the SO2 flux in order to derive the CO2 output. At Turrialba, CO2/SO2 ratios fluctuated, between March 12 and 19, between 1.1 and 5.7, and the CO2flux was evaluated at ~1000-1350 t/d (6). At Telica, between March 23 and April 8, a somewhat higher CO2/SO2 ratio was observed (3.3 ± 1.0), although the CO2 flux was evaluated at only ~100-500 t/d (6). At San Cristobal, where observations were taken between April 11 and 15, the CO2/SO2 ratio ranged between 1.8 and 7.4, with a mean CO2 flux of 753 t/d. These measurements contribute refining the current estimates of the total CO2 output from the Central American Volcanic Arc (7). Symonds, R.B. et al., (2001). J. Volcanol. Geotherm. Res., 108, 303-341 Burton, M. R. et al. (2013). Reviews in

  5. Electrical activity during the 2006 Mount St. Augustine volcanic eruptions

    Science.gov (United States)

    Thomas, Ronald J.; Krehbiel, Paul R.; Rison, William; Edens, H. E.; Aulich, G. D.; McNutt, S.R.; Tytgat, Guy; Clark, E.

    2007-01-01

    By using a combination of radio frequency time-of-arrival and interferometer measurements, we observed a sequence of lightning and electrical activity during one of Mount St. Augustine's eruptions. The observations indicate that the electrical activity had two modes or phases. First, there was an explosive phase in which the ejecta from the explosion appeared to be highly charged upon exiting the volcano, resulting in numerous apparently disorganized discharges and some simple lightning. The net charge exiting the volcano appears to have been positive. The second phase, which followed the most energetic explosion, produced conventional-type discharges that occurred within plume. Although the plume cloud was undoubtedly charged as a result of the explosion itself, the fact that the lightning onset was delayed and continued after and well downwind of the eruption indicates that in situ charging of some kind was occurring, presumably similar in some respects to that which occurs in normal thunderstorms.

  6. The new Andean Regional Office of Astronomy for Development (ROAD)

    Science.gov (United States)

    Char, Farid; Forero-Romero, Jaime

    2015-08-01

    The Andean Regional Office of Astronomy for Development (ROAD) is a new effort in South America to serve several goals in astronomical development. Six countries (Bolivia, Colombia, Chile, Ecuador, Perú and Venezuela) will work together, representing a common language block in the Andean region and focusing on develop strategies to strengthen the professional research, education and popularization of astronomy. Our current Working Structure comprises a ROAD Coordinator and Coordinators per Task Force, as well as Organizing Committees, Collaborators and Volunteers.The participating institutions of this new ROAD have been involved in many projects involving each of the current OAD’s Task Forces: research, schools and children and public, exploring educational activities/material to be shared among the Andean countries, standardizing the knowledge and creating inspirational experiences. We expect to generate many efforts in order to bring a more homogeneous activity in each Andean country, taking into account the special role of Chile in global astronomy, due to its great conditions for astronomy and the involvement of many professional observatories, universities and astronomy institutions.Our current (and upcoming) most relevant activities includes: Andean Schools on Astronomy, Andean Graduate Program and Massive Open Online Courses (TF1); Virtual Training Sessions and Teaching material for the visually impaired students; Annual TF2 meeting to gather all the collaborators (TF2); Development for planetariums and Communicating Astronomy with the Public (TF3). The Andean region, in the other hand, will also be involved in at least two important events: the CAP Meeting in May 2016 and the XV LARIM in October 2016 (both in Colombia); and Chile will bid to host the XXXI IAU GA in 2021, with the aim of show the great advances in astronomical development from the Andean region and South America.

  7. Self-potential, geoelectric and magnetotelluric studies in Italian active volcanic areas

    OpenAIRE

    Di Mai, R.; Mauriello, P.; Patella, D.; Petrillo, Z.; Piscitelli, S.; Siniscalchi, A.; Veneruso, M.

    1997-01-01

    We present the results of self-potential, geoelectric and magnetotelluric studies in Italian active volcanic areas as essential contributions both to structural modeling and to hazard evaluation. On Mt. Etna and Mt. Somma-Vesuvius complexes structural modeling was emphasized due to a lack of global information involving the whole apparatuses, at least from the electrical point of view. Hazard investigation was, instead, investigated with high resolution techniques on the island of Vulcano, wh...

  8. Unraveling the Lipolytic Activity of Thermophilic Bacteria Isolated from a Volcanic Environment

    OpenAIRE

    Stathopoulou, Panagiota M.; Savvides, Alexander L.; Karagouni, Amalia D.; Hatzinikolaou, Dimitris G.

    2013-01-01

    In a bioprospecting effort towards novel thermostable lipases, we assessed the lipolytic profile of 101 bacterial strains isolated from the volcanic area of Santorini, Aegean Sea, Greece. Screening of lipase activity was performed both in agar plates and liquid cultures using olive oil as carbon source. Significant differences were observed between the two screening methods with no clear correlation between them. While the percentage of lipase producing strains identified in agar plates was o...

  9. Quantifying unsteadiness and dynamics of pulsatory volcanic activity

    Science.gov (United States)

    Dominguez, L.; Pioli, L.; Bonadonna, C.; Connor, C. B.; Andronico, D.; Harris, A. J. L.; Ripepe, M.

    2016-06-01

    Pulsatory eruptions are marked by a sequence of explosions which can be separated by time intervals ranging from a few seconds to several hours. The quantification of the periodicities associated with these eruptions is essential not only for the comprehension of the mechanisms controlling explosivity, but also for classification purposes. We focus on the dynamics of pulsatory activity and quantify unsteadiness based on the distribution of the repose time intervals between single explosive events in relation to magma properties and eruptive styles. A broad range of pulsatory eruption styles are considered, including Strombolian, violent Strombolian and Vulcanian explosions. We find a general relationship between the median of the observed repose times in eruptive sequences and the viscosity of magma given by η ≈ 100 ṡtmedian. This relationship applies to the complete range of magma viscosities considered in our study (102 to 109 Pa s) regardless of the eruption length, eruptive style and associated plume heights, suggesting that viscosity is the main magma property controlling eruption periodicity. Furthermore, the analysis of the explosive sequences in terms of failure time through statistical survival analysis provides further information: dynamics of pulsatory activity can be successfully described in terms of frequency and regularity of the explosions, quantified based on the log-logistic distribution. A linear relationship is identified between the log-logistic parameters, μ and s. This relationship is useful for quantifying differences among eruptive styles from very frequent and regular mafic events (Strombolian activity) to more sporadic and irregular Vulcanian explosions in silicic systems. The time scale controlled by the parameter μ, as a function of the median of the distribution, can be therefore correlated with the viscosity of magmas; while the complexity of the erupting system, including magma rise rate, degassing and fragmentation efficiency

  10. Evidence of volcanic and glacial activity in Chryse and Acidalia Planitiae, Mars

    Science.gov (United States)

    Martinez-Alonso, Sara; Mellon, Michael T.; Banks, Maria E.; Keszthelyi, Laszlo P.; McEwen, Alfred S.

    2011-01-01

    Chryse and Acidalia Planitiae show numerous examples of enigmatic landforms previously interpreted to have been influenced by a water/ice-rich geologic history. These landforms include giant polygons bounded by kilometer-scale arcuate troughs, bright pitted mounds, and mesa-like features. To investigate the significance of the last we have analyzed in detail the region between 60°N, 290°E and 10°N, 360°E utilizing HiRISE (High Resolution Imaging Science Experiment) images as well as regional-scale data for context. The mesas may be analogous to terrestrial tuyas (emergent sub-ice volcanoes), although definitive proof has not been identified. We also report on a blocky unit and associated landforms (drumlins, eskers, inverted valleys, kettle holes) consistent with ice-emplaced volcanic or volcano-sedimentary flows. The spatial association between tuya-like mesas, ice-emplaced flows, and further possible evidence of volcanism (deflated flow fronts, volcanic vents, columnar jointing, rootless cones), and an extensive fluid-rich substratum (giant polygons, bright mounds, rampart craters), allows for the possibility of glaciovolcanic activity in the region.Landforms indicative of glacial activity on Chryse/Acidalia suggest a paleoclimatic environment remarkably different from today's. Climate changes on Mars (driven by orbital/obliquity changes) or giant outflow channel activity could have resulted in ice-sheet-related landforms far from the current polar caps.

  11. Relationship between the latest activity of mare volcanism and topographic features of the Moon

    Science.gov (United States)

    Kato, Shinsuke; Morota, Tomokatsu; Yamaguchi, Yasushi; Watanabe, Sei-ichiro; Otake, Hisashi; Ohtake, Makiko

    2016-04-01

    Lunar mare basalts provide insights into compositions and thermal history of lunar mantle. According to crater counting analysis with remote sensing data, the model ages of mare basalt units indicate a second peak of magma activity at the end of mare volcanism (~2 Ga), and the latest eruptions were limited in the Procellarum KREEP Terrane (PKT), which has high abundances of heat-producing elements. In order to understand the mechanism for causing the second peak and its magma source, we examined the correlation between the titanium contents and eruption ages of mare basalt units using compositional and chronological data updated by SELENE/Kaguya. Although no systematic relationship is observed globally, a rapid increase in mean titanium (Ti) content occurred at 2.3 Ga in the PKT, suggesting that the magma source of mare basalts changed at that time. The high-Ti basaltic eruption, which occurred at the late stage of mare volcanism, can be correlated with the second peak of volcanic activity at ~2 Ga. The latest volcanic activity can be explained by a high-Ti hot plume originated from the core-mantle boundary. If the hot plume was occurred, the topographic features formed by the hot plume may be remained. We calculated the difference between topography and selenoid and found the circular feature like a plateau in the center of the PKT, which scale is ~1000 km horizontal and ~500 m vertical. We investigated the timing of ridge formation in the PKT by using stratigraphic relationship between mare basalts and ridges. The ridges were formed before and after the high-Ti basaltic eruptions and seem to be along with the plateau. These results suggest that the plateau formation is connected with the high-Ti basaltic eruptions.

  12. MIGRATION OF SEISMIC AND VOLCANIC ACTIVITY AS DISPLAY OF WAVE GEODYNAMIC PROCESS

    Directory of Open Access Journals (Sweden)

    Alexander V. Vikulin

    2012-01-01

    Full Text Available Publications about the earthquake foci migration have been reviewed. An important result of such studies is establishment of wave nature of seismic activity migration that is manifested by two types of rotational waves; such waves are responsible for interaction between earthquakes foci and propagate with different velocities. Waves determining long-range interaction of earthquake foci are classified as Type 1; their limiting velocities range from 1 to 10 cm/s. Waves determining short-range interaction of foreshocks and aftershocks of individual earthquakes are classified as Type 2; their velocities range from 1 to 10 km/s. According to the classification described in [Bykov, 2005], these two types of migration waves correspond to slow and fast tectonic waves. The most complete data on earthquakes (for a period over 4.1 million of years and volcanic eruptions (for 12 thousand years of the planet are consolidated in a unified systematic format and analyzed by methods developed by the authors. For the Pacific margin, Alpine-Himalayan belt and the Mid-Atlantic Ridge, which are the three most active zones of the Earth, new patterns of spatial and temporal distribution of seismic and volcanic activity are revealed; they correspond to Type 1 of rotational waves. The wave nature of the migration of seismic and volcanic activity is confirmed. A new approach to solving problems of geodynamics is proposed with application of the data on migration of seismic and volcanic activity, which are consolidated in this study, in combination with data on velocities of movement of tectonic plate boundaries. This approach is based on the concept of integration of seismic, volcanic and tectonic processes that develop in the block geomedium and interact with each other through rotating waves with a symmetric stress tensor. The data obtained in this study give grounds to suggest that a geodynamic value, that is mechanically analogous to an impulse

  13. Andean region study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-10-01

    New opportunities for climate change mitigation arising from a higher energy integration among Andean Pact nations were analysed within the framework of the UNEP/GEF Project. Apart from the search for regional mitigation actions, the study was mainly aimed at detecting methodological problems which arise when passing from a strictly national view to the co-ordination of regional actions to deal with climate change. In accordance with the available resources and data, and in view of the mainly methodological nature of the project, it was decided to analyse the opportunities to delve into the energy integration of the Region as regards electricity and natural gas industries and their eventual impact on the emission of greenhouse gases. Although possibilities of setting up electricity and natural gas markets are real, their impacts on GHG emission from the energy system would not prove substantially higher than those which the nations could achieve through the use of their own energy resources, in view that the Andean systems are competitive rather than complementary. More in-depth studies and detail information will be required - unavailable for the present study - to be able to properly evaluate all benefits associated with higher energy integration. Nevertheless, the supply of natural gas to Ecuador seems to be the alternative with the highest impact on GHG emission. If we were to analyse the supply and final consumption of energy jointly, we would most certainly detect additional mitigation options resulting from higher co-operation and co-ordination in the energy field. (EHS)

  14. Mercury as a proxy for volcanic activity during extreme environmental turnover

    DEFF Research Database (Denmark)

    Sial, A.N.; Lacerda, L.D.; Ferreira, V.P.

    2013-01-01

    (KTB) and was, perhaps, responsible for dramatic climatic changes and decrease in biodiversity and mass extinction. We have used Hg concentrations as a proxy for volcanic activity and atmospheric Hg and CO2 buildup across the KTB at three localities. In the Salta Basin, Argentina, Hg contents display...... close to) this transition. At Stevns Klint, Denmark, Hg contents reached almost 250 ng·g− 1 within a 5 cm thick-clay layer, the Fiskeler Member (‘Fish Clay’) that comprises the KTB. Some co-variation between Hg and Al2O3 contents has been observed in all of the studied sections across the KTB......, suggesting that Hg is probably adsorbed onto clays. Thermo-desorption experiments in selected samples from the Yacoraite Formation showed Hg+ 2 as the major species present, which is in agreement with a volcanic origin. Combined Hg and C-isotope chemostratigraphy may become a powerful tool for the eventual...

  15. Acoustic waves in the atmosphere and ground generated by volcanic activity

    International Nuclear Information System (INIS)

    Ichihara, Mie; Lyons, John; Oikawa, Jun; Takeo, Minoru

    2012-01-01

    This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted also to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.

  16. Acoustic waves in the atmosphere and ground generated by volcanic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ichihara, Mie; Lyons, John; Oikawa, Jun; Takeo, Minoru [Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Instituto Geofisico, Escuela Politecnica Nacional, Ladron de Guevara E11-253, Aptdo 2759, Quito (Ecuador); Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)

    2012-09-04

    This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted also to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.

  17. 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.

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

    International Nuclear Information System (INIS)

    Armienta, M.A.; De la Cruz-Reyna, S.; Soler, A.; Cruz, O.; Ceniceros, N.; Aguayo, A.

    2010-01-01

    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 4 2- , Cl - and F - 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 4 produced by hydrothermal processes from magmatic SO 2 . Lower S isotopic values correlated with higher F - 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.

  19. Multi-Source Autonomous Response for Targeting and Monitoring of Volcanic Activity

    Science.gov (United States)

    Davies, Ashley G.; Doubleday, Joshua R.; Tran, Daniel Q.

    2014-01-01

    The study of volcanoes is important for both purely scientific and human survival reasons. From a scientific standpoint, volcanic gas and ash emissions contribute significantly to the terrestrial atmosphere. Ash depositions and lava flows can also greatly affect local environments. From a human survival standpoint, many people live within the reach of active volcanoes, and therefore can be endangered by both atmospheric (ash, debris) toxicity and lava flow. There are many potential information sources that can be used to determine how to best monitor volcanic activity worldwide. These are of varying temporal frequency, spatial regard, method of access, and reliability. The problem is how to incorporate all of these inputs in a general framework to assign/task/reconfigure assets to monitor events in a timely fashion. In situ sensing can provide a valuable range of complementary information such as seismographic, discharge, acoustic, and other data. However, many volcanoes are not instrumented with in situ sensors, and those that have sensor networks are restricted to a relatively small numbers of point sensors. Consequently, ideal volcanic study synergistically combines space and in situ measurements. This work demonstrates an effort to integrate spaceborne sensing from MODIS (Terra and Aqua), ALI (EO-1), Worldview-2, and in situ sensing in an automated scheme to improve global volcano monitoring. Specifically, it is a "sensor web" concept in which a number of volcano monitoring systems are linked together to monitor volcanic activity more accurately, and this activity measurement automatically tasks space assets to acquire further satellite imagery of ongoing volcanic activity. A general framework was developed for evidence combination that accounts for multiple information sources in a scientist-directed fashion to weigh inputs and allocate observations based on the confidence of an events occurrence, rarity of the event at that location, and other scientists

  20. PCDD/PCDF and dl-PCB in the ambient air of a tropical Andean city: passive and active sampling measurements near industrial and vehicular pollution sources.

    Science.gov (United States)

    Cortés, J; González, C M; Morales, L; Abalos, M; Abad, E; Aristizábal, B H

    2014-09-01

    Concentration gradients were observed in gas and particulate phases of PCDD/F originating from industrial and vehicular sources in the densely populated tropical Andean city of Manizales, using passive and active air samplers. Preliminary results suggest greater concentrations of dl-PCB in the mostly gaseous fraction (using quarterly passive samplers) and greater concentrations of PCDD/F in the mostly particle fraction (using daily active samplers). Dioxin-like PCB predominance was associated with the semi-volatility property, which depends on ambient temperature. Slight variations of ambient temperature in Manizales during the sampling period (15°C-27°C) may have triggered higher concentrations in all passive samples. This was the first passive air sampling monitoring of PCDD/F conducted in an urban area of Colombia. Passive sampling revealed that PCDD/F in combination with dioxin-like PCB ranged from 16 WHO-TEQ2005/m(3) near industrial sources to 7 WHO-TEQ2005/m(3) in an intermediate zone-a reduction of 56% over 2.8 km. Active sampling of particulate phase PCDD/F and dl-PCB were analyzed in PM10 samples. PCDD/F combined with dl-PCB ranged from 46 WHO-TEQ2005/m(3) near vehicular sources to 8 WHO-TEQ2005/m(3) in the same intermediate zone, a reduction of 83% over 2.6 km. Toxic equivalent quantities in both PCDD/F and dl-PCB decreased toward an intermediate zone of the city. Variations in congener profiles were consistent with variations expected from nearby sources, such as a secondary metallurgy plant, areas of concentrated vehicular emissions and a municipal solid waste incinerator (MSWI). These variations in congener profile measurements of dioxins and dl-PCBs in passive and active samples can be partly explained by congener variations expected from the various sources. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. The ELSA tephra stack: Volcanic activity in the Eifel during the last 500,000 years

    Science.gov (United States)

    Förster, Michael W.; Sirocko, Frank

    2016-07-01

    Tephra layers of individual volcanic eruptions are traced in several cores from Eifel maar lakes, drilled between 1998 and 2014 by the Eifel Laminated Sediment Archive (ELSA). All sediment cores are dated by 14C and tuned to the Greenland interstadial succession. Tephra layers were characterized by the petrographic composition of basement rock fragments, glass shards and characteristic volcanic minerals. 10 marker tephra, including the well-established Laacher See Tephra and Dümpelmaar Tephra can be identified in the cores spanning the last glacial cycle. Older cores down to the beginning of the Elsterian, show numerous tephra sourced from Strombolian and phreatomagmatic eruptions, including the 40Ar/39Ar dated differentiated tephra from Glees and Hüttenberg. In total, at least 91 individual tephra can be identified since the onset of the Eifel volcanic activity at about 500,000 b2k, which marks the end of the ELSA tephra stack with 35 Strombolian, 48 phreatomagmatic and 8 tephra layers of evolved magma composition. Many eruptions cluster near timings of the global climate transitions at 140,000, 110,000 and 60,000 b2k. In total, the eruptions show a pattern, which resembles timing of phases of global sea level and continental ice sheet changes, indicating a relation between endogenic and exogenic processes.

  2. 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

  3. A new model for the development of the active Afar volcanic margin

    Science.gov (United States)

    Pik, Raphaël; Stab, Martin; Bellahsen, Nicolas; Leroy, Sylvie

    2016-04-01

    Volcanic passive margins, that represent more than the three quarters of continental margins worldwide, are privileged witnesses of the lithospheric extension processes thatform new oceanic basins. They are characterized by voluminous amounts of underplated, intruded and extruded magmas, under the form of massive lavas prisms (seaward-dipping reflectors, or SDR) during the course of thinning and stretching of the lithosphere, that eventually form the ocean-continent transition. The origin and mechanisms of formation of these objects are still largely debated today. We have focussed our attention in the last few years on the Afar volcanic province which represents an active analogue of such volcanic margins. We explored the structural and temporal relationships that exist between the development of the major thinning and stretching structures and the magmatic production in Central Afar. Conjugate precise fieldwork analysis along with lavas geochronology allowed us to revisit the timing and style of the rift formation, since the early syn-rift period of time in the W-Afar marginal area to present days. Extension is primarily accommodated over a wide area at the surface since the very initial periods of extension (~ 25 Ma) following the emplacement of Oligocene CFBs. We propose in our reconstruction of central Afar margin history that extension has been associated with important volumes of underplated mafic material that compensate crustal thinning. This has been facilitated by major crustal-scale detachments that help localize the thinning and underplating at depth. In line with this 'magmatic wide-rift' mode of extension, we demonstrate that episodic extension steps alternate with more protracted magmatic phases. The production of syn-rift massive flood basalts (~ 4 Ma) occurs after early thinning of both the crust and the lithosphere, which suggests that SDR formation, is controlled by previous tectonic event. We determined how the melting regime evolved in

  4. Soil organic matter dynamics at the paramo and puna highlands in the Andean mountains

    Science.gov (United States)

    Ángeles Muñoz, M.; Faz, Ángel; Mermut, Ahmet R.; Zornoza, Raúl

    2014-05-01

    Mountains and uplands represent the most diverse and fragile ecosystems in the world, cover about 20% of the terrestrial surface and are distributed across all continents and major ecoregions. The Andean Plateau is the main mountain range of the American continent and one of the largest in the world with more than 7,500 km. The soil organic matter is a corner stone in the fertility management of the Andean agriculture as well as in the erosion control. However, its role is still much unknown in these ecosystems. Moreover, the influence of current global climatic change on soil organic C reservoirs and dynamics is still not clearly understood. The aim of this work was to review the soil C dynamics and the implication of the soil organic matter in the fertility management, erosion control, conservation of biodiversity and global climate change to improve the knowledge on the mountain Andean highlands. Climate, landscape, soil C pools, biomass and management were studied. In general, the Andean climate is affected by three main factors: ocean currents, winds and orography characterized by an abrupt topography. The entire Andean belt is segmented into the Northern, Central and Southern Andes. Northern Andes are called paramo and are characterized by humid climate while Central and Southern Andes dryer zones are called puna. Most of the region is tectonically and volcanically active. Sedimentary rocks predominated in the paramo while sedimentary, igneous and metamorphic ones prevailed in the puna. The most common soils were Andosols, Regosols, Umbrisols and Histosols. The cold and wet climate and the low atmospheric pressure favored organic matter accumulation in the soil. The accumulation of organic matter is further enhanced by the formation of organomineral complexes strongly resistant to the microbial breakdown mainly in the paramo. High organic C contents were observed in the paramo (10%) oppositely to the low contents found in the dryer puna (1%). The C/N ratio

  5. Geochemical and geophysical monitoring activities in Campo de Calatrava Volcanic Field (Spain)

    Science.gov (United States)

    Luengo-Oroz, Natividad; Villasante-Marcos, Víctor; López-Díaz, Rubén; Calvo, Marta; Albert, Helena; Domínguez Cerdeña, Itahiza

    2017-04-01

    The Campo de Calatrava Volcanic Field (CCVF) or Spanish Central Volcanic Zone is located in central continental Spain (Ciudad Real province) and covers about 5000 km2. It includes around 240 eruptive centers, mainly monogenetic basaltic cones but also explosive maar structures. According to K-Ar geochronology, its main activity phase occurred during Pliocene and Pleistocene epochs (between 5 and 1.7 Ma) and involved alkaline to ultraalkaline magmas, although an older ultrapotassic phase is dated around 8.7-6.4 Ma. However, some recent works have proposed Holocene ages for some of the volcanic products, opening the possibility of considering the CCVF "active" according to international standards. Responding to this situation, the Instituto Geográfico Nacional (IGN) has initiated geochemical and geophysical monitoring activities in the CCVF. Here, we describe these ongoing efforts and we report results about groundwater geochemistry at several natural highly-gaseous springs in the area (hervideros), as well as soil temperature, CO2 diffuse flux from the soil and electrical self-potential data mapped on a small degassing structure called La Sima. In order to analyze microseismicity or any seismic anomaly in the CCVF, a seismic station has also been installed close to this degassing structure. Physicochemical parameters (temperature, pH, Eh and electric conductivity) were measured in situ in four springs and samples were taken in order to analyze major ions and trace elements. Total composition of dissolved gases and helium isotopic ratios were also determined. To complete soil temperature, self-potential and gas prospections performed in La Sima, soil gases were sampled at the bottom of the structure at a depth of 20 cm. Analysis of the total gas composition found 957400 ppm of CO2. Low values of O2 and N2 were also detected (5600 and 24800 ppm respectively).

  6. A spaceborne inventory of volcanic activity in Antarctica and southern oceans, 2000-10

    Science.gov (United States)

    Patrick, Matthew R.; Smellie, John L.

    2015-01-01

    Of the more than twenty historically active volcanoes in Antarctica and the sub-Antarctic region only two, to our knowledge, host any ground-based monitoring instruments. Moreover, because of their remoteness, most of the volcanoes are seldom visited, thus relegating the monitoring of volcanism in this region almost entirely to satellites. In this study, high temporal resolution satellite data from the Hawaii Institute of Geophysics and Planetology's MODVOLC system using MODIS (Moderate Resolution Imaging Spectroradiometer) are complemented with high spatial resolution data (ASTER, or Advanced Spaceborne Thermal Emission and Reflection Radiometer, and similar sensors) to document volcanic activity throughout the region during the period 2000–10. Five volcanoes were observed in eruption (Mount Erebus, Mount Belinda, Mount Michael, Heard Island and McDonald Island), which were predominantly low-level and effusive in nature. Mount Belinda produced tephra, building a cinder cone in addition to an extensive lava field. Five volcanoes exhibited detectable thermal, and presumed fumarolic, activity (Deception, Zavodovski, Candlemas, Bristol, and Bellingshausen islands). A minor eruption reported at Marion Island was not detected in our survey due to its small size. This study also discovered a new active vent on Mount Michael, tracked dramatic vent enlargement on Heard Island, and provides an improved picture of the morphology of some of the volcanoes.

  7. Self-potential, geoelectric and magnetotelluric studies in Italian active volcanic areas

    Directory of Open Access Journals (Sweden)

    A. Siniscalchi

    1997-06-01

    Full Text Available We present the results of self-potential, geoelectric and magnetotelluric studies in Italian active volcanic areas as essential contributions both to structural modeling and to hazard evaluation. On Mt. Etna and Mt. Somma-Vesuvius complexes structural modeling was emphasized due to a lack of global information involving the whole apparatuses, at least from the electrical point of view. Hazard investigation was, instead, investigated with high resolution techniques on the island of Vulcano, where intense unrest phenomena have long been recorded.

  8. Monitoring Io's Volcanic Activity in the Visible and Infrared from JUICE - It's All About (Eruption) Style

    Science.gov (United States)

    Davies, A. G.; Matson, D.; McEwen, A. S.; Keszthelyi, L. P.

    2012-12-01

    The European Space Agency's Jupiter Icy Moons Explorer (JUICE) will provide many opportunities for long-range monitoring of Io's extraordinary silicate, high-temperature volcanic activity [1, 2]. A considerable amount of valuable work can be performed even with relatively low-spatial-resolution observations [2]. Techniques developed from the examination and analysis of Galileo Near Infrared Mapping Spectrometer (NIMS) data, as well as observations of terrestrial silicate volcanic activity, allows the identification of likely eruption style [2] at many locations where the entire eruption is sub-pixel. Good temporal coverage, especially for episodic eruptions (including high-energy "outburst" eruptions), is important for modelling purposes. With opportunities to observe Io on a regular basis (hours-days) during cruise/orbital reduction phases, a visible-to-near-infrared mapping spectrometer (covering ~0.4-5.5 μm) is the best instrument to chart the magnitude and variability of Io's volcanic activity, allowing comparison with an existing and constantly expanding set of Io observations [e.g. 1, 3]. The eruption temperature of Io's dominant silicate lava, a constraint on interior composition and conditions, is a major unanswered question in the wake of the Galileo mission [1]. A careful approach to instrument design is needed to ensure that observations by both imager and IR spectrometer on JUICE are capable of determining lava eruption temperature [e.g., 4] in low spatial resolution data. With an ideal thermal target (e.g., an outburst eruption, or the proposed lava lake at Pele) the imager should obtain multi-spectral data in a rapid sequence to allow stability of the thermal source to be quantified. Observations by imager and spectrometer have to be contemporaneous and unsaturated. References: [1] Davies, A. (2007) "Volcanism on Io", Cam. Univ. Press. [2] Davies, A. et al. (2010) JVGR, 194, 75-99. [3] Veeder, G. et al. (2012) Icarus, 219, 701-722. [4] Davies, A. et

  9. Seismic evidence for arc segmentation, active magmatic intrusions and syn-rift fault system in the northern Ryukyu volcanic arc

    Science.gov (United States)

    Arai, Ryuta; Kodaira, Shuichi; Takahashi, Tsutomu; Miura, Seiichi; Kaneda, Yoshiyuki

    2018-04-01

    Tectonic and volcanic structures of the northern Ryukyu arc are investigated on the basis of multichannel seismic (MCS) reflection data. The study area forms an active volcanic front in parallel to the non-volcanic island chain in the eastern margin of the Eurasian plate and has been undergoing regional extension on its back-arc side. We carried out a MCS reflection experiment along two across-arc lines, and one of the profiles was laid out across the Tokara Channel, a linear bathymetric depression which demarcates the northern and central Ryukyu arcs. The reflection image reveals that beneath this topographic valley there exists a 3-km-deep sedimentary basin atop the arc crust, suggesting that the arc segment boundary was formed by rapid and focused subsidence of the arc crust driven by the arc-parallel extension. Around the volcanic front, magmatic conduits represented by tubular transparent bodies in the reflection images are well developed within the shallow sediments and some of them are accompanied by small fragments of dipping seismic reflectors indicating intruded sills at their bottoms. The spatial distribution of the conduits may suggest that the arc volcanism has multiple active outlets on the seafloor which bifurcate at crustal depths and/or that the location of the volcanic front has been migrating trenchward over time. Further distant from the volcanic front toward the back-arc (> 30 km away), these volcanic features vanish, and alternatively wide rift basins become predominant where rapid transitions from normal-fault-dominant regions to strike-slip-fault-dominant regions occur. This spatial variation in faulting patterns indicates complex stress regimes associated with arc/back-arc rifting in the northern Okinawa Trough.[Figure not available: see fulltext.

  10. Multiteide Project: Multiparametric characterization of the activity of Teide-Pico Viejo volcanic system

    Science.gov (United States)

    Domínguez Cerdeña, Itahiza; Villasante-Marcos, Victor; Meletlidis, Stavros; Sainz-Maza, Sergio; Abella, Rafael; Torres, Pedro A.; Sánchez, Nieves; Luengo-Oroz, Natividad; José Blanco, María; García-Cañada, Laura; Pereda de Pablo, Jorge; Lamolda, Héctor; Moure, David; Del Fresno, Carmen; Finizola, Anthony; Felepto, Alicia

    2017-04-01

    Teide-Pico Viejo complex stands for one of the major natural volcanic hazards in the Canary Islands, due to the expected types of eruptions in the area and the high number of inhabitants in Tenerife Island. Therefore, it is necessary to have a volcanic alert system able to afford a precise assessment of the current state of the complex. For this purpose, the knowledge of the expected signals at each volcanic activity level is required. Moreover, the external effects that can affect the measurements shall be distinguished, external influences as the atmosphere are qualitatively known but have not been quantified yet. The objective of the project is to collect, analyze and jointly and continuously evaluate over time geophysical, geodetic, geochemical and meteorological data from the Teide-Pico Viejo complex and its surroundings. A continuous multiparametric network have been deployed in the area, which, together with the data provided by the Volcano Monitoring Network of the Instituto Geográfico Nacional (IGN) and data from other institutions will provide a comprehensive set of data with high resolution in both space and time. This multiparametric network includes a seismic array, two self-potential lines for continuous measurements, five magnetometers and two weather stations. The network will be complemented with 8 CGPS stations, one tiltmeter, 10 seismic stations, and four thermometric stations on the fumaroles of Teide volcano that IGN already manage in Tenerife. The data will be completed with the results from different repeated surveys of self potential, soil temperature and CO2 diffuse flux in several pre-established areas on top of Teide throughout the entire duration of project. During the project, new computation tools will be developed to study the correlation between the different parameters analyzed. The results obtained will characterize the possible seasonal fluctuations of each parameter and the variations related to meteorological phenomena. In

  11. New Approach for Monitoring Seismic and Volcanic Activities Using Microwave Radiometer Data

    Science.gov (United States)

    Maeda, Takashi; Takano, Tadashi

    Interferograms formed from the data of satellite-borne synthetic aperture radar (SAR) enable us to detect slight land-surface deformations related to volcanic eruptions and earthquakes. Currently, however, we cannot determine when land-surface deformations occurred with high time resolution since the time lag between two scenes of SAR used to form interferograms is longer than the recurrent period of the satellite carrying it (several tens of days). In order to solve this problem, we are investigating new approach to monitor seismic and vol-canic activities with higher time resolution from satellite-borne sensor data, and now focusing on a satellite-borne microwave radiometer. It is less subject to clouds and rainfalls over the ground than an infrared spectrometer, so more suitable to observe an emission from land sur-faces. With this advantage, we can expect that thermal microwave energy by increasing land surface temperatures is detected before a volcanic eruption. Additionally, laboratory experi-ments recently confirmed that rocks emit microwave energy when fractured. This microwave energy may result from micro discharges in the destruction of materials, or fragment motions with charged surfaces of materials. We first extrapolated the microwave signal power gener-ated by rock failures in an earthquake from the experimental results and concluded that the microwave signals generated by rock failures near the land surface are strong enough to be detected by a satellite-borne radiometer. Accordingly, microwave energy generated by rock failures associated with a seismic activity is likely to be detected as well. However, a satellite-borne microwave radiometer has a serious problem that its spatial res-olution is too coarse compared to SAR or an infrared spectrometer. In order to raise the possibility of detection, a new methodology to compensate the coarse spatial resolution is es-sential. Therefore, we investigated and developed an analysis method to detect local

  12. Theory for Deducing Volcanic Activity From Size Distributions in Plinian Pyroclastic Fall Deposits

    Science.gov (United States)

    Iriyama, Yu; Toramaru, Atsushi; Yamamoto, Tetsuo

    2018-03-01

    Stratigraphic variation in the grain size distribution (GSD) of plinian pyroclastic fall deposits reflects volcanic activity. To extract information on volcanic activity from the analyses of deposits, we propose a one-dimensional theory that provides a formula connecting the sediment GSD to the source GSD. As the simplest case, we develop a constant-source model (CS model), in which the source GSD and the source height are constant during the duration of release of particles. We assume power laws of particle radii for the terminal fall velocity and the source GSD. The CS model can describe an overall (i.e., entire vertically variable) feature of the GSD structure of the sediment. It is shown that the GSD structure is characterized by three parameters, that is, the duration of supply of particles to the source scaled by the fall time of the largest particle, ts/tM, and the power indices of the terminal fall velocity p and of the source GSD q. We apply the CS model to samples of the Worzel D ash layer and compare the sediment GSD structure calculated by using the CS model to the observed structure. The results show that the CS model reproduces the overall structure of the observed GSD. We estimate the duration of the eruption and the q value of the source GSD. Furthermore, a careful comparison of the observed and calculated GSDs reveals new interpretation of the original sediment GSD structure of the Worzel D ash layer.

  13. 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. 

  14. Antimicrobial and antioxidant activities of Gentianella multicaulis collected on the Andean Slopes of San Juan Province, Argentina.

    Science.gov (United States)

    Lima, Beatriz; Sánchez, Marianela; Luna, Lorena; Agüero, María B; Zacchino, Susana; Filippa, Eva; Palermo, Jorge A; Tapia, Alejandro; Feresin, Gabriela E

    2012-01-01

    The infusion of the aerial parts of Gentianella multicaulis (Gillies ex Griseb.) Fabris (Gentianaceae), locally known as 'nencia', is used in San Juan Province, Argentina, as stomachic and as a bitter tonic against digestive and liver problems. The bioassay-guided isolation of G. multicaulis extracts and structural elucidation of the main compounds responsible for the antifungal and free radical scavenging activities were performed. The extracts had strong free radical scavenging effects in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay (45-93% at 10 microg/mL) and ferric-reducing antioxidant power (FRAP) assay at 200 microg/mL. Demethylbellidifolin (4) had high antioxidant activity in the DPPH and FRAP assay. The dermatophytes Microsporum gypseum, Trichophyton mentagrophytes, and T. rubrum were moderately inhibited by the different extracts (MIC values of 125-250 microg/mL). Demethylbellidifolin (4), bellidifolin (5), and isobellidifolin (6) showed an antifungal effect (MIC values of 50 microg/mL), while swerchirin (3) was less active with a MIC value of 100 microg/mL. In addition, oleanolic acid (1) and ursolic acid (2) were also isolated. These findings demonstrate that Gentianella multicaulis collected in the mountains of the Province of San Juan, Argentina, is an important source of compounds with antifungal and antioxidant activities.

  15. Jupiter's Auroral Energy Input Observed by Hisaki/EXCEED and its Modulations by Io's Volcanic Activity

    Science.gov (United States)

    Tao, C.; Kimura, T.; Tsuchiya, F.; Murakami, G.; Yoshioka, K.; Kita, H.; Yamazaki, A.; Kasaba, Y.; Yoshikawa, I.; Fujimoto, M.

    2016-12-01

    Aurora is an important indicator representing the momentum transfer from the fast-rotating outer planet to the magnetosphere and the energy input into the atmosphere through the magnetosphere-ionosphere coupling. Long-term monitoring of Jupiter's northern aurora was achieved by the Extreme Ultraviolet (EUV) spectrometer called EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) onboard JAXA's Earth-orbiting planetary space telescope Hisaki until today after its launch in September 2013. We have proceeded the statistical survey of the Jupiter's auroral energy input into the upper atmosphere. The auroral electron energy is estimated using a hydrocarbon color ratio (CR) adopted for the wavelength range of EXCEED, and the emission power in the long wavelength range 138.5-144.8 nm is used as an indicator of total emitted power before hydrocarbon absorption and auroral electron energy flux. Temporal dynamic variation of the auroral intensity was detected when Io's volcanic activity and thus EUV emission from the Io plasma torus are enhanced in the early 2015. Average of the total input power over 80 days increases by 10% with sometimes sporadically more than a factor of 3 upto 7, while the CR indicates the auroral electron energy decrease by 20% during the volcanic event compared to the other period. This indicates much more increase in the current system and Joule heating which contributes heating of the upper atmosphere. We will discuss the impact of this event on the upper atmosphere and ionosphere.

  16. Seismically active fracture zones in the continental wedge above the Andean subduction zone in the Arica Elbow region

    Czech Academy of Sciences Publication Activity Database

    Vaněk, Jiří; Hanuš, Václav; Slancová, Alice; Špičák, Aleš

    2007-01-01

    Roč. 9, č. 1-4 (2007), s. 39-57 ISSN 0163-3171 R&D Projects: GA ČR GA205/95/0264; GA AV ČR IAA3012805 Grant - others:UNESCO(FR) IGCP project No. 345 Institutional research plan: CEZ:AV0Z30120515 Source of funding: V - iné verejné zdroje Keywords : continental lithosphere * Wadati-Benioff zone * seismically active zones Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  17. Hemoglobin affinity in Andean rodents

    Directory of Open Access Journals (Sweden)

    HRVOJ OSTOJIC

    2002-01-01

    Full Text Available Blood hemoglobin oxygen affinity (P50 was measured in three Andean species and in the laboratory rat (control, all raised near sea level. Chinchilla lanigera (Molina, 1792 has an altitudinal habitat range from low Andean slopes up to 3000 m., while Chinchilla brevicaudata (Waterhouse, 1848 has an altitudinal range from 3000 to 5000 m. The laboratory type guinea pig, wild type guinea pig (Cavia porcellus, (Waterhouse, 1748, and laboratory rat (Rattus norvegicus were also raised at sea level. The Andean species had high hemoglobin oxygen affinities (low P50 compared with the rat. Chinchilla brevicaudata had a higher affinity than Chinchilla lanigera. The wild type guinea pig had a higher affinity than the laboratory type. As has been shown in other species, this is another example of an inverse correlation between the altitude level and the P50 values. This is the first hemoglobin oxygen affinity study in Chinchilla brevicaudata.

  18. Geochemical constraints on the relationship between the Miocene-Pliocene volcanism and tectonics in the Palaoco and Fortunoso volcanic fields, Mendoza Region, Argentina

    DEFF Research Database (Denmark)

    Dyhr, Charlotte Thorup; Holm, Paul Martin; Llambias, Eduardo J.

    2013-01-01

    New 40Ar/39Ar analyses constrain the formation of the volcanic succession of Sierra de Palaoco in the present back-arc of the Andean Southern Volcanic Zone (SVZ), near 36°S, to the Late Miocene and assigns them to the Huincán II Formation. The composition of major and trace elements, Sr, Nd and P...

  19. Review of the Cambrian volcanic activity in Morocco: geochemical fingerprints and geotectonic implications for the rifting of West Gondwana

    Science.gov (United States)

    Pouclet, André; El Hadi, Hassan; Álvaro, J. Javier; Bardintzeff, Jacques-Marie; Benharref, Mohammed; Fekkak, Abdelilah

    2018-03-01

    Volcanic activities related to the opening of a Cambrian rift in Morocco were widespread from the Fortunian to the Cambrian Epoch 3. Numerous data are available from northwestern volcanic sites, particularly in the western High Atlas, but they are scarce from the southeastern sites. New data are documented here from the volcanic formations exposed in the Jbel Tazoult n'Ouzina of the Tafilalt Province, eastern Anti-Atlas and dated to Cambrian Epoch 2-3. The Cambrian volcanic activities recorded in the High Atlas, Anti-Atlas, and Coastal Meseta are synthesized to refine their stratigraphic setting and to characterize their magmatic affinities and fingerprints. Six volcanic pulses are determined as tholeiitic, transitional, and alkaline suites. The tholeiitic and transitional magmas originated from primitive mantle and E-MORB-type sources with a spinel- and garnet-bearing lherzolite composition. Some of them were modified by assimilation-fractional crystallisation processes during crust-mantle interactions. The alkaline magmas fit with an OIB-type and a garnet-bearing lherzolite source. The palaeogeographic distribution of the magmatic suites was controlled by the lithospheric thinning of the Cambrian Atlas Rift and lithospheric constraints of the Pan-African metacraton and West African craton.

  20. Geochemical monitoring of volcanic lakes. A generalized box model for active crater lakes

    Directory of Open Access Journals (Sweden)

    Franco Tassi

    2011-06-01

    Full Text Available

    In the past, variations in the chemical contents (SO42−, Cl−, cations of crater lake water have not systematically demonstrated any relationships with eruptive activity. Intensive parameters (i.e., concentrations, temperature, pH, salinity should be converted into extensive parameters (i.e., fluxes, changes with time of mass and solutes, taking into account all the internal and external chemical–physical factors that affect the crater lake system. This study presents a generalized box model approach that can be useful for geochemical monitoring of active crater lakes, as highly dynamic natural systems. The mass budget of a lake is based on observations of physical variations over a certain period of time: lake volume (level, surface area, lake water temperature, meteorological precipitation, air humidity, wind velocity, input of spring water, and overflow of the lake. This first approach leads to quantification of the input and output fluxes that contribute to the actual crater lake volume. Estimating the input flux of the "volcanic" fluid (Qf- kg/s –– an unmeasurable subsurface parameter –– and tracing its variations with time is the major focus during crater lake monitoring. Through expanding the mass budget into an isotope and chemical budget of the lake, the box model helps to qualitatively characterize the fluids involved. The (calculated Cl− content and dD ratio of the rising "volcanic" fluid defines its origin. With reference to continuous monitoring of crater lakes, the present study provides tips that allow better calculation of Qf in the future. At present, this study offers the most comprehensive and up-to-date literature review on active crater lakes.

  1. A late Holocene metal record of Andean climate and anthropogenic activity in lake sediments near Quelccaya Ice Cap, Peru

    Science.gov (United States)

    Beal, S. A.; Kelly, M. A.; Jackson, B. P.; Stroup, J. S.; Osterberg, E. C.

    2011-12-01

    The tropical hypothesis maintains that major changes in global climate are motivated by phenomena based at tropical latitudes. Evidence for this hypothesis lies in: modern-day observations of El Niño Southern Oscillation (ENSO); East African lake sediment records of Intertropical Convergence Zone (ITCZ) position that precede high-latitude changes; and the potential for ITCZ shifts to cause major CO2 degassing from the Southern Ocean. In order to improve the understanding of these phenomena we present an ~1800 year record of atmospheric metal deposition in a lake sediment core near Quelccaya Ice Cap, Peru (13.9 °S). In June, 2010 we collected a 1.45 meter-long core from Yanacocha - a small, closed-basin tarn that has been isolated from glacial input since ~11,200 BP. The chronology for the core is based on 4 of 6 AMS 14C dates on aquatic macrofossils and one sharp Zr/Ti anomaly at 36 cm, likely derived from the 350 BP eruption of Huaynaputina. We completely digested organic-rich core samples at 1 cm resolution using HNO3, HCl, and HF in a closed-vessel microwave system, and then analyzed the digestates for 67 metals by inductively coupled plasma mass spectrometry. Here we show fluxes of lithogenic metals (Fe, Nb, Ti, and Zr) that reflect changes in wind strength and aridity, fluxes of lithogenic metal isotopes (REEs and Pb) that reflect wind direction, and enrichment factors (EFs) of metals (Ag, As, Cd, Cu, Hg, and Pb) that reflect anthropogenic activity. Five episodic peaks in lithogenic metal fluxes, centered around 1800, 1300, 900, 600, and 100 yrs BP, are thought to result from either drier or windier conditions, potentially caused by a northern ITCZ position or a more persistent El Niño state. The provenance of atmospheric deposition, evidenced by REE ratios (light REEs / heavy REEs), suggest that high lithogenic fluxes are associated with a change in wind direction, possibly caused by a change in the ENSO state, which will be explored with forthcoming Pb

  2. On the use of UAVs at active volcanoes: a case study from Volcan de Fuego, Guatemala

    Science.gov (United States)

    Watson, M.; Chigna, G.; Wood, K.; Richardson, T.; Liu, E.; Schellenberg, B.; Thomas, H.; Naismith, A.

    2017-12-01

    Volcan de Fuego, Guatemala, is one of Central America's most active systems. More than one hundred thousand people live within ten kilometres of the summit, many of them in profound poverty. Both the summit region and the volcano's steep sided valleys present significant access challenges, mostly associated with unacceptably high risk. Unmanned aerial vehicles (UAVs) offer the opportunity to observe, map and quantify emissions of tephra, gas, lava and heat flux and, using structure from motion algorithms, model dynamic topography. During recent campaigns, the team have completed observations of changes in the summit morphology immediately prior a paroxysmal eruption, mapped the key drainage systems after the fifth of May 2017 eruption and sampled the plume for tephra and gases using a range of onboard instruments. I will present the group's findings within a broader context of hazard mitigation and physical volcanology, and discuss the future of UAVs in volcano monitoring and research.

  3. Use of Logistic Regression for Forecasting Short-Term Volcanic Activity

    Directory of Open Access Journals (Sweden)

    Mark T. Woods

    2012-08-01

    Full Text Available An algorithm that forecasts volcanic activity using an event tree decision making framework and logistic regression has been developed, characterized, and validated. The suite of empirical models that drive the system were derived from a sparse and geographically diverse dataset comprised of source modeling results, volcano monitoring data, and historic information from analog volcanoes. Bootstrapping techniques were applied to the training dataset to allow for the estimation of robust logistic model coefficients. Probabilities generated from the logistic models increase with positive modeling results, escalating seismicity, and rising eruption frequency. Cross validation yielded a series of receiver operating characteristic curves with areas ranging between 0.78 and 0.81, indicating that the algorithm has good forecasting capabilities. Our results suggest that the logistic models are highly transportable and can compete with, and in some cases outperform, non-transportable empirical models trained with site specific information.

  4. Middle Pleistocene volcanic activity dated by red thermoluminescence (RTL) - a case study from Lanzarote (Canary Islands)

    Science.gov (United States)

    von Suchodoletz, H.; Blanchard, H.; Rittner, S.; Radtke, U.; Fuchs, M.; Dietze, M.; Zöller, L.

    2009-04-01

    On Lanzarote (Canary Islands) soils were baked by Quaternary lava flows. This offers the possibility to date phases of eruptive activity by red thermoluminescence (RTL). We dated soil material baked by two different lava flows originating from the "Las Calderetas de Guatiza" volcanic chain in the northeast of the island by RTL. Furthermore, three samples of Helicidae-mollusk shells overlying one of the lava flows (site Mála) were dated using electron spin resonance (ESR). RTL datings were carried out using quartz grains 63-200 µm from baked material that were originally brought by eolian transport from the nearby Saharan desert. It appears that in spite of a baking temperature Lanzarote by RTL thus offers the possibility to further investigate the yet fragmentary Middle and Late Quaternary eruptive history of these islands.

  5. ASI-Volcanic Risk System (SRV): a pilot project to develop EO data processing modules and products for volcanic activity monitoring, first results.

    Science.gov (United States)

    Silvestri, M.; Musacchio, M.; Buongiorno, M. F.; Dini, L.

    2009-04-01

    The Project called Sistema Rischio Vulcanico (SRV) is funded by the Italian Space Agency (ASI) in the frame of the National Space Plan 2003-2005 under the Earth Observations section for natural risks management. The SRV Project is coordinated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) which is responsible at national level for the volcanic monitoring. The project philosophy is to implement, by incremental versions, specific modules which allow to process, store and visualize through Web GIS tools geophysical parameters suitable for volcanic risk management. The ASI-SRV is devoted to the development of an integrated system based on Earth Observation (EO) data to respond to specific needs of the Italian Civil Protection Department (DPC) and improve the monitoring of Italian active volcanoes during all the risk phases (Pre Crisis, Crisis and Post Crisis). The ASI-SRV system provides support to risk managers during the different volcanic activity phases and its results are addressed to the Italian Civil Protection Department (DPC). SRV provides the capability to manage the import many different EO data into the system, it maintains a repository where the acquired data have to be stored and generates selected volcanic products. The processing modules for EO Optical sensors data are based on procedures jointly developed by INGV and University of Modena. This procedures allow to estimate a number of parameters such as: surface thermal proprieties, gas, aerosol and ash emissions and to characterize the volcanic products in terms of composition and geometry. For the analysis of the surface thermal characteristics, the available algorithms allow to extract information during the prevention phase and during the Warning and Crisis phase. In the prevention phase the thermal analysis is directed to the identification of temperature variation on volcanic structure which may indicate a change in the volcanic activity state. At the moment the only sensor that

  6. Transition of neogene arc volcanism in central-western Hokkaido, viewed from K-Ar ages, style of volcanic activity, and bulk rock chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, Wataru; Iwasaki, Miyuki; Nakagawa, Mitsuhiro [Hokkaido Univ., Sapporo (Japan)

    2000-02-01

    Spatial and temporal variations in late Cenozoic volcanism of southwestern Hokkaido at the northern end of NE-Japan arc have been clarified by 261 K-Ar and 76 FT ages including 49 newly determined K-Ar ages, volcanic stratigraphy, physical volcanology and whole-rock geochemistry. Arc volcanism characterized by rocks with low-Ti and Nb, and by across-arc increase in K{sub 2}O content in these rocks has continued at least since 12 Ma. Based on volcanic stratigraphy, physical volcanology and whole-rock geochemistry, volcanism after 12 Ma can be subdivided into 4 stages, 12-5, 5-1.7, and 1.7-0 Ma. The volcanism from 12 Ma to 5 Ma extended northward widely compared with distribution of Quaternary arc volcanism (1.7-0 Ma). This suggests that the arc trench junction between Kuril and NE-Japan arc's trenches was located about 100 km northward from the present position. Since around 5 Ma until 1.7 Ma, different type of volcanism under local extension field, characterized by a group of monogenetic volcanoes of alkali basalt and shield volcanoes of calc-alkaline andesite, had occurred at northern end of the volcanic region (Takikawa-Mashike region). During and after this volcanism, the northern edge of arc volcanism in the area has migrated southward. This suggests that the trench junction has migrated about 100 km southward since {approx}5 Ma. The quaternary arc volcanism (1.7-0 Ma) has been restricted at the southern part of the region. The volcanism since 12 Ma might be influenced by oblique subduction of Pacific plate beneath Kuril arc, resulting in the formation of local back arc basin at the junction and to southward migration of the trench junction. (author)

  7. Crust-mantle contribution to Andean magmatism

    International Nuclear Information System (INIS)

    Ruiz, J; Hildreth, W; Chesley, J

    2001-01-01

    There has long been great interest in quantifying the contributions of the continental crust to continental arc magmas, such as those of the Andes using osmium isotopes (Alves et al., 1999; Borg et al., 2000; Brandon et al., 1996; McInnes et al., 1999). In general, Andean volcanic rocks of all compositions show relatively low Sr-isotope ratios and positive to mildly negative epsilon Nd values. Nonetheless, in the Southern Volcanic Zone of central Chile, basalt-andesite-dacite volcanoes along the Quaternary volcanic front were shown (by Hildreth and Moorbath, 1988) to have latitudinally systematic chemical variations, as well as a monotonic increase in 87Sr/Sr86 from ca. 0.7035 to 0.7055 and a decrease in epsilon Nd values from ca. +3 to -1. The isotopic variations correlate with basement elevation of the volcanic edifices and with Bouguer gravity anomalies, both of which are thought to reflect along-arc variations in thickness and average age of the underlying crust. Volcanoes with the most evolved isotopic signatures were fed through the thickest crust. Correlation of chemical and isotopic variations with crustal thickness was interpreted to be caused by Melting (of deep-crustal host rocks), Assimilation, Storage, and Homogenization (MASH) of mantle-derived magmas in long-lived lower-crustal reservoirs beneath each center prior to eruption. We have now determined Os-isotope ratios for a sample suite from these volcanoes (33-36 S lat.), representing a range of crustal thickness from ca. 60-35 km. The samples range in MgO from ca. 8-4% and in SiO2 from 51-57%. The most evolved eruptive products occur above the thickest crust and have 87Sr/86Sr ratios of 0.7054 and epsilon Nd values of -1.5. The 187Os/188Os ratios correlate with the other isotopic systems and with crustal thickness. Volcanoes on the thinnest crust have 187Os/188Os ratios of 0.18-0.21. Those on the thickest crust have 187Os/188Os ratios as high as 0.64. All the Os values are much too radiogenic to

  8. Volcanic and Tectonic Activity in the Red Sea Region (2004-2013): Insights from Satellite Radar Interferometry and Optical Imagery

    KAUST Repository

    Xu, Wenbin

    2015-01-01

    due to insufficient in-situ data and remoteness of some of the activity. In this dissertation, I have used satellite remote sensing to derive new information about several recent volcanic and tectonic events in the Red Sea region. I first report

  9. Impacts of forest harvest on active carbon and microbial properties of a volcanic ash cap soil in northern Idaho

    Science.gov (United States)

    Deborah S. Page-Dumroese; Matt D. Busse; Steven T. Overby; Brian D. Gardner; Joanne M. Tirocke

    2015-01-01

    Soil quality assessments are essential for determining impacts on belowground microbial community structure and function. We evaluated the suitability of active carbon (C), a rapid field test, as an indicator of soil biological quality in five paired forest stands (clear cut harvested 40 years prior and unharvested) growing on volcanic ash-cap soils in northern Idaho....

  10. Volcanic complexes in the eastern ridge of the Canary Islands: the Miocene activity of the island of Fuerteventura

    Science.gov (United States)

    Ancochea, E.; Brändle, J. L.; Cubas, C. R.; Hernán, F.; Huertas, M. J.

    1996-03-01

    Fuerteventura has been since early stages of its growth the result of three different adjacent large volcanic complexes: Southern, Central and Northern. The definition of these volcanic complexes and their respective growing episodes is based on volcano-stratigraphic, morphological and structural criteria, particularly radial dyke swarms. Each complex has its own prolonged history that might be longer than 10 m.y. During that time, several periods of activity alternating with gaps accompanied by important erosion took place. The evolution of each volcanic complex has been partially independent but all the three are affected by at least three Miocene tectonic phases that controlled considerably their activity. The volcanic complexes are deeply eroded and partially submerged. In the core of the Northern and the Central volcanic complexes there is a set of submarine and plutonic rocks intensely traversed by a dyke swarm, known as the Basal Complex. The Basal Complex has been interpreted in different ways but all previous authors have considered it to be prior to the subaerial shield stage of the island. Here we advance the idea that the Basal Complex represent the submarine growing stage of the volcanic complexes and the hypabyssal roots (plutons and dykes) of their successive subaerial growing episodes. Two seamounts situated nearby, southwest of the island, might be interpreted as remains of two other major volcanoes. These two volcanoes, together with those forming the present emerged island of Fuerteventura, and finally those of Famara and Los Ajaches situated further north on Lanzarote constitute a chain of volcanoes located along a lineation which is subparallel to the northwestern African coastline and which may relate to early Atlantic spreading trends in the area.

  11. Sustained effects of volcanic ash on biofilm stoichiometry, enzyme activity and community composition in North- Patagonia streams.

    Science.gov (United States)

    Carrillo, Uara; Díaz-Villanueva, Verónica; Modenutti, Beatriz

    2018-04-15

    Volcanic eruptions are extreme perturbations that affect ecosystems. These events can also produce persistent effects in the environment for several years after the eruption, with increased concentrations of suspended particles and the introduction of elements in the water column. On 4th June 2011, the Puyehue-Cordón Caulle Volcanic Complex (40.59°S-72.11°W, 2200m.a.s.l.) erupted explosively in southern Chile. The area affected by the volcano was devastated; a thick layer of volcanic ash (up to 30cm) was deposited in areas 50 km east of the volcano towards Argentina. The aim of the present study was to evaluate the effect of volcanic ash deposits on stream ecosystems four years after the eruption, comparing biofilm stoichiometry, alkaline phosphatase activity, and primary producer's assemblage in streams which were severely affected by the volcano with unaffected streams. We confirmed in the laboratory that ash deposited in the catchment of affected streams still leach phosphorus (P) into the water four years after eruption. Results indicate that affected streams still receive volcanic particles and that these particles release P, thus stream water exhibits high P concentration. Biofilm P content was higher and the C:P ratio lower in affected streams compared to unaffected streams. As a consequence of less P in unaffected streams, the alkaline phosphatase activity was higher compared to affected streams. Cyanobacteria increased their abundances (99.9% of total algal biovolume) in the affected streams suggesting that the increase in P may positively affect this group. On the contrary, unaffected streams contained a diatom dominant biofilm. In this way, local heterogeneity was created between sub-catchments located within 30 km of each other. These types of events should be seen as opportunities to gather valuable ecological information about how severe disturbances, like volcanic eruptions, shape landscapes and lotic systems for several years after the event

  12. Evaluation on changes caused by volcanic activities in the groundwater environment as a natural barrier for the HLW disposal. Literature survey and groundwater observation conducted at Mt. Iwate

    International Nuclear Information System (INIS)

    Mahara, Yasunori; Nakata, Eiji; Tanaka, Kazuhiro

    2000-01-01

    It is very important in the site characterization for the HLW disposal to understand changes in geochemical performances caused by volcanic activities in the groundwater environment as the natural barrier. The various effects and its magnitude of changes were listed up and were filed from literature surveys of the correlation between volcanic activities and hydrological can geochemical changes (e.g. water temperature, water pressure, water level, dissolved gas concentration of He and Rn, isotopic ratio of He, and chloride concentration) in volcanic aquifer. However, it is difficult to evaluate the magnitude of impacts, which volcanic activities will give to the groundwater environment in the natural barrier, through only the literature surveys. We have started monitoring of groundwater level and changes in groundwater quality, since volcanic activities have enhanced at Mt. Iwate from June in 1998. Judging from variation of isotopic ratio of dissolved He in groundwater, a prompt and sharp signals indicating volcanic activities will easily be found in shallow groundwater and discharged ponds. On the other hands, geochemical conditions in deep groundwater surroundings from some 100 m to 1000 m deep will be very stable, if the area being more than 5 km apart from the volcanic active center. Consequently, our observed results suggest that the groundwater environment which is not directly disturbed by the underground magmatic activities spreads under the area that is connected to trench side of the volcanic front. (author)

  13. Unraveling the lipolytic activity of thermophilic bacteria isolated from a volcanic environment.

    Science.gov (United States)

    Stathopoulou, Panagiota M; Savvides, Alexander L; Karagouni, Amalia D; Hatzinikolaou, Dimitris G

    2013-01-01

    In a bioprospecting effort towards novel thermostable lipases, we assessed the lipolytic profile of 101 bacterial strains isolated from the volcanic area of Santorini, Aegean Sea, Greece. Screening of lipase activity was performed both in agar plates and liquid cultures using olive oil as carbon source. Significant differences were observed between the two screening methods with no clear correlation between them. While the percentage of lipase producing strains identified in agar plates was only 17%, lipolytic activity in liquid culture supernatants was detected for 74% of them. Nine strains exhibiting elevated extracellular lipase activities were selected for lipase production and biochemical characterization. The majority of lipase producers revealed high phylogenetic similarity with Geobacillus species and related genera, whilst one of them was identified as Aneurinibacillus sp. Lipase biosynthesis strongly depended on the carbon source that supplemented the culture medium. Olive oil induced lipase production in all strains, but maximum enzyme yields for some of the strains were also obtained with Tween-80, mineral oil, and glycerol. Partially purified lipases revealed optimal activity at 70-80°C and pH 8-9. Extensive thermal stability studies revealed marked thermostability for the majority of the lipases as well as a two-step thermal deactivation pattern.

  14. Unraveling the Lipolytic Activity of Thermophilic Bacteria Isolated from a Volcanic Environment

    Directory of Open Access Journals (Sweden)

    Panagiota M. Stathopoulou

    2013-01-01

    Full Text Available In a bioprospecting effort towards novel thermostable lipases, we assessed the lipolytic profile of 101 bacterial strains isolated from the volcanic area of Santorini, Aegean Sea, Greece. Screening of lipase activity was performed both in agar plates and liquid cultures using olive oil as carbon source. Significant differences were observed between the two screening methods with no clear correlation between them. While the percentage of lipase producing strains identified in agar plates was only 17%, lipolytic activity in liquid culture supernatants was detected for 74% of them. Nine strains exhibiting elevated extracellular lipase activities were selected for lipase production and biochemical characterization. The majority of lipase producers revealed high phylogenetic similarity with Geobacillus species and related genera, whilst one of them was identified as Aneurinibacillus sp. Lipase biosynthesis strongly depended on the carbon source that supplemented the culture medium. Olive oil induced lipase production in all strains, but maximum enzyme yields for some of the strains were also obtained with Tween-80, mineral oil, and glycerol. Partially purified lipases revealed optimal activity at 70–80°C and pH 8-9. Extensive thermal stability studies revealed marked thermostability for the majority of the lipases as well as a two-step thermal deactivation pattern.

  15. Quaternary Tectonic and Climatic Processes shaping the Central Andean hyperarid forearc (southern Peru)

    Science.gov (United States)

    Audin, Laurence; Benavente, Carlos; Zerathe, Swann; Saillard, Marianne; Hall, Sarah R.; Farber, Daniel L.

    2015-04-01

    Understanding the forearc structure and processes related to Quaternary evolution and uplift of the Western Andean Cordillera remains an outstanding scientific issue. Models of Andean Plateau evolution based on Tertiary volcanic stratigraphy since 5Ma suggest that the deformation was focused along the eastern margin of the plateau and that minimal uplift occurred along the Pacific margin. On the contrary, new tectonic data and Quaternary surface 10Be dating highlight the presence of recently active deformation, incision and alluvial processes within the upper Andean forearc together with a regional uplift of the coastal zone. Additionally, the high obliquity observed in the northern Arica Bend region makes it an ideal target to discuss whether partitioning of the oblique convergence is accommodated by the neotectonic features that dissect the Quaternary forearc. Our goals are both to decipher the Quaternary tectonic and climatic processes shaping the hyperarid forearc along strike and across strike. Finally, we aim to quantify the respective influence of these factors in the overall uplift of the Western Andes. Indeed, sequences of pediment surfaces, landslide products, paleolake deposits and marine terraces found along the oblique Peruvian margin are a unique set of datable markers that can be used to quantify the rates of Quaternary processes. In this study, we focus on the southern Peru hyperarid Atacama area where regional surfaces and tectonic markers (scarps, folds, temporary streams and paleolake levels offsets…) are well preserved for the Quaternary timescale. Numerous landsliding events align on the major fault segments and reflect Plio-Pleistocene climatic and tectonic activity together with filled and strath terraces. As the present day sea-level is one of the highest levels recorded for Quaternary time span, any emerged marine terrace is preserved by tectonic coastal uplift. In particular, the geomorphic and chronologic correlation between marine and

  16. Water-quality effects on Baker Lake of recent volcanic activity at Mount Baker, Washington

    Science.gov (United States)

    Bortleson, Gilbert Carl; Wilson, Reed T.; Foxworthy, B.L.

    1976-01-01

    Increased volcanic activity on Mount Baker, which began in March 1975, represents the greatest known activity of a Cascade Range volcano since eruptions at Lassen Peak, Calif. during 1914-17. Emissions of dust and increased emanations of steam, other gases, and heat from the Sherman Crater area of the mountain focused attention on the possibility of hazardous events, including lava flows, pyroclastic eruptions, avalanches, and mudflows. However, the greatest undesirable natural results that have been observed after one year of the increased activity are an increase in local atmospheric pollution and a decrease in the quality of some local water resources, including Baker Lake. Baker Lake, a hydropower reservoir behind Upper Baker Dam, supports a valuable fishery resource and also is used for recreation. The lake's feedwater is from Baker River and many smaller streams, some of which, like Boulder Creek, drain parts of Mount Baker. Boulder Creek receives water from Sherman Crater, and its channel is a likely route for avalanches or mudflows that might originate in the crater area. Boulder Creek drains only about 5 percent of the total drainage area of Baker Lake, but during 1975 carried sizeable but variable loads of acid and dissolved minerals into the lake. Sulfurous gases and the fumarole dust from Sherman Crater are the main sources for these materials, which are brought into upper Boulder Creek by meltwater from the crater. In September 1973, before the increased volcanic activity, Boulder Creek near the lake had a pH of 6.0-6.6; after the increase the pH ranged as low as about 3.5. Most nearby streams had pH values near 7. On April 29, in Boulder Creek the dissolved sulfate concentration was 6 to 29 times greater than in nearby creeks or in Baker River; total iron was 18-53 times greater than in nearby creeks; and other major dissolved constituents generally 2 to 7 times greater than in the other streams. The short-term effects on Baker Lake of the acidic

  17. New Style of Volcanic Eruption Activity Identified in Galileo NIMS data at Marduk Fluctus, Io

    Science.gov (United States)

    Davies, A. G.; Davies, R. L.; Veeder, G. J.; de Kleer, K.; De Pater, I.; Matson, D.

    2017-12-01

    Analysis of observations of Marduk Fluctus, Io, by the Galileo Near Infrared Mapping Spectrometer (NIMS) reveals a style of volcanic activity not previously seen on Io - a very short-duration, highly-changeable, powerful thermal event, similar to what might be expected from a strombolian-like explosion. Marduk Fluctus is a persistent active volcano characterised by ≈3600 km2 of silicate flows [1]. Between 1996 and 2001, NIMS obtained 44 observations of Marduk Fluctus at a wide variety of spatial and spectral resolutions. Six observations were obtained during Galileo orbit E4, with five nighttime observations obtained on 1996 Dec 19 in the space of less than three hours. Three of these observations were each separated by one minute. Compared to the previous observation obtained a few hours earlier, the first two of these three observations show an order of magnitude increase in spectral radiance (corrected for emission angle). Spectral radiance then dropped back to the background level one minute later. The emission angles for these five E4 observations are large (>70°), but even without the emission angle radiance correction the spike in activity is still a factor of five larger than the pre- and post-spike radiances. The NIMS spectrum of the central observation shows a shift in peak of thermal emission to short wavelengths characteristic of the exposure of a large area of incandescent lava. The rapid increase and decrease in activity suggests an equally rapid physical process, the most likely being a large strombolian explosion that generated small clasts that cooled rapidly. The presence of such events provide an additional volcanic process that can be imaged with the intent of determining lava composition from eruption temperature, an important constraint on internal composition and state. For this particular eruption type, eruption temperature can be constrained if non-saturated, multiple-wavelength IR observations are obtained simultaneously and with very

  18. Soil gas radon and volcanic activity at El Hierro (Canary Islands) before and after the 2011-2012 submarine eruption

    Science.gov (United States)

    Barrancos, J.; Padilla, G.; Hernandez Perez, P. A.; Padron, E.; Perez, N.; Melian Rodriguez, G.; Nolasco, D.; Dionis, S.; Rodriguez, F.; Calvo, D.; Hernandez, I.

    2012-12-01

    El Hierro is the youngest and southernmost island of the Canarian archipelago and represents the summit of a volcanic shield elevating from the surrounding seafloor at depth of 4000 m to up to 1501 m above sea level. The island is believed to be near the present hotspot location in the Canaries with the oldest subaerial rocks dated at 1.12 Ma. The subaerial parts of the El Hierro rift zones (NE, NW and S Ridges) are characterized by tightly aligned dyke complexes with clusters of cinder cones as their surface expressions. Since July 16, 2011, an anomalous seismicity at El Hierro Island was recorded by IGN seismic network. Volcanic tremor started at 05:15 hours on October 10, followed on the afternoon of October 12 by a green discolouration of seawater, strong bubbling and degassing indicating the initial stage of submarine volcanic eruption at approximately 2 km off the coast of La Restinga, El Hierro. Soil gas 222Rn and 220Rn activities were continuously measured during the period of the recent volcanic unrest occurred at El Hierro, at two different geochemical stations, HIE02 and HIE03. Significant increases in soil 222Rn activity and 222Rn/220Rn ratio from the soil were observed at both stations prior the submarine eruption off the coast of El Hierro, showing the highest increases before the eruption onset and the occurrence of the strongest seismic event (M=4.6). A statistical analysis showed that the long-term trend of the filtered data corresponded closely to the seismic energy released during the volcanic unrest. The observed increases of 222Rn are related to the rock fracturing processes (seismic activity) and the magmatic CO2 outflow increase, as observed in HIE03 station. Under these results, we find that continuous soil radon studies are important for evaluating the volcanic activity of El Hierro and they demonstrate the potential of applying continuous monitoring of soil radon to improve and optimize the detection of early warning signals of future

  19. Volcanic risk

    International Nuclear Information System (INIS)

    Rancon, J.P.; Baubron, J.C.

    1995-01-01

    This project follows the previous multi-disciplinary studies carried out by the French Bureau de Recherches Geologiques et Minieres (BRGM) on the two active volcanoes of the French lesser Antilles: Mt Pelee (Martinique) and Soufriere (Guadeloupe) for which geological maps and volcanic risk studies have been achieved. The research program comprises 5 parts: the study of pyroclastic deposits from recent eruptions of the two volcanoes for a better characterization of their eruptive phenomenology and a better definition of crisis scenarios; the study of deposits and structures of active volcanoes from Central America and the study of eruptive dynamics of andesite volcanoes for a transposition to Antilles' volcanoes; the starting of a methodological multi-disciplinary research (volcanology, geography, sociology...) on the volcanic risk analysis and on the management of a future crisis; and finally, the development of geochemical survey techniques (radon, CO 2 , H 2 O) on active volcanoes of Costa-Rica and Europe (Fournaise, Furnas, Etna) and their application to the Soufriere. (J.S.). 9 refs., 3 figs

  20. 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.

  1. Volcanism on Io

    Science.gov (United States)

    Davies, Ashley Gerard

    2014-03-01

    Preface; Introduction; Part I. Io, 1610 to 1995: Galileo to Galileo: 1. Io, 1610-1979; 2. Between Voyager and Galileo: 1979-95; 3. Galileo at Io; Part II. Planetary Volcanism: Evolution and Composition: 4. Io and Earth: formation, evolution, and interior structure; 5. Magmas and volatiles; Part III. Observing and Modeling Volcanic Activity: 6. Observations: thermal remote sensing of volcanic activity; 7. Models of effusive eruption processes; 8. Thermal evolution of volcanic eruptions; Part IV. Galileo at Io: the Volcanic Bestiary: 9. The view from Galileo; 10. The lava lake at Pele; 11. Pillan and Tvashtar: lava fountains and flows; 12. Prometheus and Amirani: Effusive activity and insulated flows; 13. Loki Patera: Io's powerhouse; 14. Other volcanoes and eruptions; Part V. Volcanism on Io: The Global View: 15. Geomorphology: paterae, shields, flows and mountains; 16. Volcanic plumes; 17. Hot spots; Part VI. Io after Galileo: 18. Volcanism on Io: a post-Galileo view; 19. The future of Io observations; Appendix 1; Appendix 2; References; Index.

  2. Soil CO2 efflux measurement network by means of closed static chambers to monitor volcanic activity at Tenerife, Canary Islands

    Science.gov (United States)

    Amonte, Cecilia; García-Merino, Marta; Asensio-Ramos, María; Melián, Gladys; García-Hernández, Rubén; Pérez, Aaron; Hernández, Pedro A.; Pérez, Nemesio M.

    2017-04-01

    Tenerife (2304 km2) is the largest of the Canary Islands and has developed a central volcanic complex (Cañadas edifice), that started to grow about 3.5 My ago. Coeval with the construction of the Cañadas edifice, shield basaltic volcanism continued until the present along three rift zones oriented NW-SE, NE-SW and NS (hereinafter referred as NW, NE and NS respectively). Main volcanic historical activity has occurred along de NW and NE rift-zones, although summit cone of Teide volcano, in central volcanic complex, is the only area of the island where surface geothermal manifestations are visible. Uprising of deep-seated gases occurs along the aforementioned volcanic structures causing diffuse emissions at the surface environment of the rift-zones. In the last 20 years, there has been considerable interest in the study of diffuse degassing as a powerful tool in volcano monitoring programs. Diffuse degassing studies are even more important volcanic surveillance tool at those volcanic areas where visible manifestations of volcanic gases are absent. Historically, soil gas and diffuse degassing surveys in volcanic environments have focused mainly on CO2 because it is, after water vapor, the most abundant gas dissolved in magma. One of the most popular methods used to determine CO2 fluxes in soil sciences is based on the absorption of CO2 through an alkaline medium, in its solid or liquid form, followed by gravimetric, conductivity, or titration analyses. In the summer of 2016, a network of 31 closed static chambers was installed, covering the three main structural zones of Tenerife (NE, NW and NS) as well as Cañadas Caldera with volcanic surveillance porpoises. 50 cc of 0.1N KOH solution is placed inside the chamber to absorb the CO2 released from the soil. The solution is replaced weekly and the trapped CO2 is then analyzed at the laboratory by titration. The are expressed as weekly integrated CO2 efflux values. The CO2 efflux values ranged from 3.2 to 12.9 gṡm-2

  3. Evidence for sub-lacustrine volcanic activity in Lake Bolsena (central Italy) revealed by high resolution seismic data sets

    Science.gov (United States)

    Lindhorst, Katja; Krastel, Sebastian; Wagner, Bernd; Schuerer, Anke

    2017-06-01

    The Bolsena caldera that formed between 0.6 and 0.2 Ma has a well preserved structural rim, which makes it an ideal site to study the tectonic and volcanic evolution of calderas. However, the main area is covered by a 150 m deep lake which makes it rather difficult to investigate the subsurface structure directly. To overcome this problem new high resolution hydro-acoustic surveys using a multichannel reflection seismic system and a sediment echo-sounder system were conducted in September 2012. As space was limited we used a rowing boat towed by a rubber boat to handle a 36 m long and 24 channel streamer to receive seismic reflections produced using a Mini GI-Gun (0.25 l). The subsurface structure of Lake Bolsena was imaged up to a sediment depth of 190 m, which is estimated to have filled over a period of 333 kyrs. However, massive pyroclastic flow deposits found in the deeper parts of the basin indicate an initial infill of volcanic deposits from two adjacent younger calderas, the Latera (W) and Montefiascone (SE) calderas. Our data suggest that the caldera has a long history of active volcanism, because the lacustrine sediments show post-sedimentary influences of geothermal fluids. We mapped several mound structures at various stratigraphic depths. Two volcanic structures outcrop at the modern lake surface implying recent activity. One of these structures is hardly covered by sediments and has a crater-like feature in its summit. The other structure shows a pockmark-like depression on top. Another observable feature is a partially sediment filled crater located in the western part of the lake which further implies the existence of a magma chamber located beneath the Bolsena caldera. Since the late Pleistocene and Holocene, the sedimentation was mainly hemipelagic evidenced by a sediment drape of up to 10 m thick sediment drape on the uppermost sediments. Beneath the drape we found evidence for a distal tephra layer likely related to an explosive eruption from

  4. Foreland sedimentary record of Andean mountain building during advancing and retreating subduction

    Science.gov (United States)

    Horton, Brian K.

    2016-04-01

    As in many ocean-continent (Andean-type) convergent margins, the South American foreland has long-lived (>50-100 Myr) sedimentary records spanning not only protracted crustal shortening, but also periods of neutral to extensional stress conditions. A regional synthesis of Andean basin histories is complemented by new results from the Mesozoic Neuquén basin system and succeeding Cenozoic foreland system of west-central Argentina (34-36°S) showing (1) a Late Cretaceous shift from backarc extension to retroarc contraction and (2) an anomalous mid-Cenozoic (~40-20 Ma) phase of sustained nondeposition. New detrital zircon U-Pb geochronological results from Jurassic through Neogene clastic deposits constrain exhumation of the evolving Andean magmatic arc, retroarc thrust belt, foreland basement uplifts, and distal eastern craton. Abrupt changes in sediment provenance and distal-to-proximal depositional conditions can be reconciled with a complex Mesozoic-Cenozoic history of extension, post-extensional thermal subsidence, punctuated tectonic inversion involving thick- and thin-skinned shortening, alternating phases of erosion and rapid accumulation, and overlapping igneous activity. U-Pb age distributions define the depositional ages of several Cenozoic stratigraphic units and reveal a major late middle Eocene-earliest Miocene (~40-20 Ma) hiatus in the Malargüe foreland basin. This boundary marks an abrupt shift in depositional conditions and sediment sources, from Paleocene-middle Eocene distal fluviolacustrine deposition of sediments from far western volcanic sources (Andean magmatic arc) and subordinate eastern cratonic basement (Permian-Triassic Choiyoi igneous complex) to Miocene-Quaternary proximal fluvial and alluvial-fan deposition of sediments recycled from emerging western sources (Malargüe fold-thrust belt) of Mesozoic basin fill originally derived from basement and magmatic arc sources. Neogene eastward advance of the fold-thrust belt involved thick

  5. Complex explosive volcanic activity on the Moon within Oppenheimer crater, Icarus

    Science.gov (United States)

    Bennett, Kristen A; Horgan, Briony H N; Gaddis, Lisa R.; Greenhagen, Benjamin T; Allen, Carlton C.; Hayne, Paul O; Bell, James F III; Paige, David A.

    2016-01-01

    Oppenheimer Crater is a floor-fractured crater located within the South Pole-Aitken basin on the Moon, and exhibits more than a dozen localized pyroclastic deposits associated with the fractures. Localized pyroclastic volcanism on the Moon is thought to form as a result of intermittently explosive Vulcanian eruptions under low effusion rates, in contrast to the higher-effusion rate, Hawaiian-style fire fountaining inferred to form larger regional deposits. We use Lunar Reconnaissance Orbiter Camera images and Diviner Radiometer mid-infrared data, Chandrayaan-1 orbiter Moon Mineralogy Mapper near-infrared spectra, and Clementine orbiter Ultraviolet/Visible camera images to test the hypothesis that the pyroclastic deposits in Oppenheimer crater were emplaced via Vulcanian activity by constraining their composition and mineralogy. Mineralogically, we find that the deposits are variable mixtures of orthopyroxene and minor clinopyroxene sourced from the crater floor, juvenile clinopyroxene, and juvenile iron-rich glass, and that the mineralogy of the pyroclastics varies both across the Oppenheimer deposits as a whole and within individual deposits. We observe similar variability in the inferred iron content of pyroclastic glasses, and note in particular that the northwest deposit, associated with Oppenheimer U crater, contains the most iron-rich volcanic glass thus far identified on the Moon, which could be a useful future resource. We propose that this variability in mineralogy indicates variability in eruption style, and that it cannot be explained by a simple Vulcanian eruption. A Vulcanian eruption should cause significant country rock to be incorporated into the pyroclastic deposit; however, large areas within many of the deposits exhibit spectra consistent with high abundances of juvenile phases and very little floor material. Thus, we propose that at least the most recent portion of these deposits must have erupted via a Strombolian or more continuous fire

  6. 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.

  7. Satellite Monitoring of Accumulation of Strain in the Earth's Crust Related to Seismic and Volcanic Activity

    Science.gov (United States)

    Arellano-Baeza, A. A.

    2009-12-01

    Our studies have shown that the strain energy accumulation deep in the Earth’s crust that precedes seismic and volcanic activity can be detected by applying a lineament extraction technique to the high-resolution multispectral satellite images. A lineament is a straight or a somewhat curved feature in a satellite image, which it is possible to detect by a special processing of images based on directional filtering and or Hough transform. We analyzed tens of earthquakes occurred in the Pacific coast of the South America with the magnitude > 4 Mw, using ASTER/TERRA multispectral satellite images for detection and analysis of changes in the system of lineaments previous to a strong earthquake. All events were located in the regions with small seasonal variations and limited vegetation to facilitate the tracking of features associated with the seismic activity only. It was found that the number and orientation of lineaments changed significantly about one month before an earthquake approximately, and a few months later the system returns to its initial state. This effect increases with the earthquake magnitude. It also was shown that the behavior of lineaments associated to the volcano seismic activity is opposite to that obtained previously for earthquakes. This discrepancy can be explained assuming that in the last case the main reason of earthquakes is compression and accumulation of strength in the Earth’s crust due to subduction of tectonic plates, whereas in the first case we deal with the inflation of a volcano edifice due to elevation of pressure and magma intrusion. The results obtained made it possible to include this research as a part of scientific program of Chilean Remote Sensing Satellite mission to be launched in 2010.

  8. Impact of solar versus volcanic activity variations on tropospheric temperatures and precipitation during the Dalton Minimum

    Science.gov (United States)

    Anet, J. G.; Muthers, S.; Rozanov, E. V.; Raible, C. C.; Stenke, A.; Shapiro, A. I.; Brönnimann, S.; Arfeuille, F.; Brugnara, Y.; Beer, J.; Steinhilber, F.; Schmutz, W.; Peter, T.

    2014-05-01

    The aim of this work is to elucidate the impact of changes in solar irradiance and energetic particles versus volcanic eruptions on tropospheric global climate during the Dalton Minimum (DM, AD 1780-1840). Separate variations in the (i) solar irradiance in the UV-C with wavelengths λ 250 nm, (iii) in energetic particle spectrum, and (iv) volcanic aerosol forcing were analyzed separately, and (v) in combination, by means of small ensemble calculations using a coupled atmosphere-ocean chemistry-climate model. Global and hemispheric mean surface temperatures show a significant dependence on solar irradiance at λ > 250 nm. Also, powerful volcanic eruptions in 1809, 1815, 1831 and 1835 significantly decreased global mean temperature by up to 0.5 K for 2-3 years after the eruption. However, while the volcanic effect is clearly discernible in the Southern Hemispheric mean temperature, it is less significant in the Northern Hemisphere, partly because the two largest volcanic eruptions occurred in the SH tropics and during seasons when the aerosols were mainly transported southward, partly because of the higher northern internal variability. In the simulation including all forcings, temperatures are in reasonable agreement with the tree ring-based temperature anomalies of the Northern Hemisphere. Interestingly, the model suggests that solar irradiance changes at λ Dalton Minimum. This downscales the importance of top-down processes (stemming from changes at λ 250 nm). Reduction of irradiance at λ > 250 nm leads to a significant (up to 2%) decrease in the ocean heat content (OHC) between 0 and 300 m in depth, whereas the changes in irradiance at λ < 250 nm or in energetic particles have virtually no effect. Also, volcanic aerosol yields a very strong response, reducing the OHC of the upper ocean by up to 1.5%. In the simulation with all forcings, the OHC of the uppermost levels recovers after 8-15 years after volcanic eruption, while the solar signal and the different

  9. Impact of solar vs. volcanic activity variations on tropospheric temperatures and precipitation during the Dalton Minimum

    Science.gov (United States)

    Anet, J. G.; Muthers, S.; Rozanov, E. V.; Raible, C. C.; Stenke, A.; Shapiro, A. I.; Brönnimann, S.; Arfeuille, F.; Brugnara, Y.; Beer, J.; Steinhilber, F.; Schmutz, W.; Peter, T.

    2013-11-01

    The aim of this work is to elucidate the impact of changes in solar irradiance and energetic particles vs. volcanic eruptions on tropospheric global climate during the Dalton Minimum (DM, 1780-1840 AD). Separate variations in the (i) solar irradiance in the UV-C with wavelengths λ 250 nm, (iii) in energetic particle spectrum, and (iv) volcanic aerosol forcing were analyzed separately, and (v) in combination, by means of small ensemble calculations using a coupled atmosphere-ocean chemistry-climate-model. Global and hemispheric mean surface temperatures show a significant dependence on solar irradiance at λ > 250 nm. Also, powerful volcanic eruptions in 1809, 1815, 1831 and 1835 significantly decrease global mean temperature by up to 0.5 K for 2-3 yr after the eruption. However, while the volcanic effect is clearly discernible in the southern hemispheric mean temperature, it is less significant in the Northern Hemisphere, partly because the two largest volcanic eruptions occurred in the SH tropics and during seasons when the aerosols were mainly transported southward, partly because of the higher northern internal variability. In the simulation including all forcings, temperatures are in reasonable agreement with the tree-ring-based temperature anomalies of the Northern Hemisphere. Interestingly, the model suggests that solar irradiance changes at λ Dalton Minimum. This downscales the importance of top-down processes (stemming from changes at λ 250 nm). Reduction of irradiance at λ > 250 nm leads to a significant (up to 2%) decrease of the ocean heat content (OHC) between the 0 and 300 m of depth, whereas the changes in irradiance at λ < 250 nm or in energetic particle have virtually no effect. Also, volcanic aerosol yields a very strong response, reducing the OHC of the upper ocean by up to 1.5%. In the simulation with all forcings, the OHC of the uppermost levels recovers after 8-15 yr after volcanic eruption, while the solar signal and the different

  10. 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

  11. Diffuse CO_{2} degassing monitoring of the oceanic active volcanic island of El Hierro, Canary Islands, Spain

    Science.gov (United States)

    Hernández, Pedro A.; Norrie, Janice; Withoos, Yannick; García-Merino, Marta; Melián, Gladys; Padrón, Eleazar; Barrancos, José; Padilla, Germán; Rodríguez, Fátima; Pérez, Nemesio M.

    2017-04-01

    Even during repose periods, volcanoes release large amounts of gases from both visible (fumaroles, solfataras, plumes) and non-visible emanations (diffuse degassing). In the last 20 years, there has been considerable interest in the study of diffuse degassing as a powerful tool in volcano monitoring programs, particularly in those volcanic areas where there are no visible volcanic-hydrothermal gas emissions. Historically, soil gas and diffuse degassing surveys in volcanic environments have focused mainly on CO2 because it is, after water vapor, the most abundant gas dissolved in magma. As CO2 travels upward by advective-diffusive transport mechanisms and manifests itself at the surface, changes in its flux pattern over time provide important information for monitoring volcanic and seismic activity. Since 1998, diffuse CO2 emission has been monitored at El Hierro Island, the smallest and south westernmost island of the Canarian archipelago with an area of 278 km2. As no visible emanations occur at the surface environment of El Hierro, diffuse degassing studies have become the most useful geochemical tool to monitor the volcanic activity in this volcanic island. The island experienced a volcano-seismic unrest that began in July 2011, characterized by the location of a large number of relatively small earthquakes (MHierro at depths between 8 and 15 km. On October 12, 2011, a submarine eruption was confirmed during the afternoon of October 12, 2011 by visual observations off the coast of El Hierro, about 2 km south of the small village of La Restinga in the southernmost part of the island. During the pre-eruptive and eruptive periods, the time series of the diffuse CO2 emission released by the whole island experienced two significant increases. The first started almost 2 weeks before the onset of the submarine eruption, reflecting a clear geochemical anomaly in CO2 emission, most likely due to increasing release of deep seated magmatic gases to the surface. The second

  12. Integration of geophysical datasets by a conjoint probability tomography approach: application to Italian active volcanic areas

    Directory of Open Access Journals (Sweden)

    D. Patella

    2008-06-01

    Full Text Available We expand the theory of probability tomography to the integration of different geophysical datasets. The aim of the new method is to improve the information quality using a conjoint occurrence probability function addressed to highlight the existence of common sources of anomalies. The new method is tested on gravity, magnetic and self-potential datasets collected in the volcanic area of Mt. Vesuvius (Naples, and on gravity and dipole geoelectrical datasets collected in the volcanic area of Mt. Etna (Sicily. The application demonstrates that, from a probabilistic point of view, the integrated analysis can delineate the signature of some important volcanic targets better than the analysis of the tomographic image of each dataset considered separately.

  13. Evidence of volcanic activity in the base of the Pendencia Formation, onshore Potiguar Basin; Evidencia de atividade vulcanica na base da Formacao Pendencia, Bacia Potiguar emersa

    Energy Technology Data Exchange (ETDEWEB)

    Anjos, S.M.C.; Souza, R.S. de; Sombra, C.L. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Silva Scuta, M. da [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    1990-10-01

    The occurrence of volcanic rocks on the Pendencia Formation on the onshore part of Potiguar Basin, the porosity and permeability characteristics, are presented. The studies suggest that the evidence of the volcanic activity occurred associated with the rift process, all the wells drilling in the basin presents profiles characteristics at those volcanos-sedimentary sequences found in other sedimentary basins, and the lithic sandstones permit the conclusion that the occurrence of under water volcanic activity is contemporary of sedimentation in the Pendencia Lake. 4 figs., 8 refs.

  14. Constraining Silicate Weathering Processes in an Active Volcanic Complex: Implications for the Long-term Carbon Cycle

    Science.gov (United States)

    Washington, K.; West, A. J.; Hartmann, J.; Amann, T.; Hosono, T.; Ide, K.

    2017-12-01

    While analyzing geochemical archives and carbon cycle modelling can further our understanding of the role of silicate weathering as a sink in the long-term carbon cycle, it is necessary to study modern weathering processes to inform these efforts. A recent compilation of data from rivers draining basaltic catchments estimates that rock weathering in active volcanic fields (AVFs) consumes atmospheric CO2 approximately three times faster than in inactive volcanic fields (IVFs), suggesting that the eruption and subsequent weathering of large igneous provinces likely played a major role in the carbon cycle in the geologic past [1]. The study demonstrates a significant correlation between catchment mean annual temperature (MAT) and atmospheric CO2 consumption rate for IVFs. However CO2 consumption due to weathering of AVFs is not correlated with MAT as the relationship is complicated by variability in hydrothermal fluxes, reactive surface area, and groundwater flow paths. To investigate the controls on weathering processes in AVFs, we present data for dissolved and solid weathering products from Mount Aso Caldera, Japan. Aso Caldera is an ideal site for studying the how the chemistry of rivers draining an AVF is impacted by high-temperature water/rock interactions, volcanic ash weathering, and varied groundwater flow paths and residence times. Samples were collected over five field seasons from two rivers and their tributaries, cold groundwater springs, and thermal springs. These samples capture the region's temperature and precipitation seasonality. Solid samples of unaltered volcanic rocks, hydrothermally-altered materials, volcanic ash, a soil profile, and suspended and bedload river sediments were also collected. The hydrochemistry of dissolved phases were analyzed at the University of Hamburg, while the mineralogy and geochemical compositions of solid phases were analyzed at the Natural History Museum of Los Angeles. This work will be discussed in the context of

  15. Morpho-structural evolution of a volcanic island developed inside an active oceanic rift: S. Miguel Island (Terceira Rift, Azores)

    Science.gov (United States)

    Sibrant, A. L. R.; Hildenbrand, A.; Marques, F. O.; Weiss, B.; Boulesteix, T.; Hübscher, C.; Lüdmann, T.; Costa, A. C. G.; Catalão, J. C.

    2015-08-01

    The evolution of volcanic islands is generally marked by fast construction phases alternating with destruction by a variety of mass-wasting processes. More specifically, volcanic islands located in areas of intense regional deformation can be particularly prone to gravitational destabilisation. The island of S. Miguel (Azores) has developed during the last 1 Myr inside the active Terceira Rift, a major tectonic structure materializing the present boundary between the Eurasian and Nubian lithospheric plates. In this work, we depict the evolution of the island, based on high-resolution DEM data, stratigraphic and structural analyses, high-precision K-Ar dating on separated mineral phases, and offshore data (bathymetry and seismic profiles). The new results indicate that: (1) the oldest volcanic complex (Nordeste), composing the easternmost part of the island, was dominantly active between ca. 850 and 750 ka, and was subsequently affected by a major south-directed flank collapse. (2) Between at least 500 ka and 250 ka, the landslide depression was massively filled by a thick lava succession erupted from volcanic cones and domes distributed along the main E-W collapse scar. (3) Since 250 kyr, the western part of this succession (Furnas area) was affected by multiple vertical collapses; associated plinian eruptions produced large pyroclastic deposits, here dated at ca. 60 ka and less than 25 ka. (4) During the same period, the eastern part of the landslide scar was enlarged by retrogressive erosion, producing the large Povoação valley, which was gradually filled by sediments and young volcanic products. (5) The Fogo volcano, in the middle of S. Miguel, is here dated between ca. 270 and 17 ka, and was affected by, at least, one southwards flank collapse. (6) The Sete Cidades volcano, in the western end of the island, is here dated between ca. 91 and 13 ka, and experienced mutliple caldera collapses; a landslide to the North is also suspected from the presence of a

  16. Exploring the potential of an Andean fruit

    NARCIS (Netherlands)

    Olivares Tenorio, Mary Luz

    2017-01-01

    Cape gooseberry is a fruit cultivated in Andean countries. Currently it is available some international markets, besides the domestic Andean market. Colombia is the major producer and export country at the moment. The value chain of cape gooseberry faces several barriers of technological and

  17. Volcanic Activity on lo at the Time of the Ulysses Encounter.

    Science.gov (United States)

    Spencer, J R; Howell, R R; Clark, B E; Klassen, D R; O'connor, D

    1992-09-11

    The population of heavy ions in lo's torus is ultimately derived from lo volcanism. Groundbased infrared observations of lo between October 1991 and March 1992, contemporaneous with the 8 February 1992 Ulysses observations of the lo torus, show that volcanic thermal emission was at the low end of the normal range at all lo longitudes during this period. In particular, the dominant hot spot Loki was quiescent. Resolved images show that there were at least four hot spots on lo's Jupiter-facing hemisphere, including Loki and a long-lived spot on the leading hemisphere (Kanehekili), of comparable 3.5-micrometer brightness but higher temperature.

  18. Groundwater flow processes and mixing in active volcanic systems: the case of Guadalajara (Mexico)

    Science.gov (United States)

    Hernández-Antonio, A.; Mahlknecht, J.; Tamez-Meléndez, C.; Ramos-Leal, J.; Ramírez-Orozco, A.; Parra, R.; Ornelas-Soto, N.; Eastoe, C. J.

    2015-09-01

    other active volcanic systems on Earth.

  19. Volcanic and Tectonic Activity in the Red Sea Region (2004-2013): Insights from Satellite Radar Interferometry and Optical Imagery

    KAUST Repository

    Xu, Wenbin

    2015-04-01

    Studying recent volcanic and tectonic events in the Red Sea region is important for improving our knowledge of the Red Sea plate boundary and for regional geohazard assessments. However, limited information has been available about the past activity due to insufficient in-situ data and remoteness of some of the activity. In this dissertation, I have used satellite remote sensing to derive new information about several recent volcanic and tectonic events in the Red Sea region. I first report on three volcanic eruptions in the southern Red Sea, the 2007-8 Jebel at Tair eruption and the 2011-12 & 2013 Zubair eruptions, which resulted in formation of two new islands. Series of high- resolution optical images were used to map the extent of lava flows and to observe and analyze the growth and destructive processes of the new islands. I used Interferometric Synthetic Aperture Radar (InSAR) data to study the evolution of lava flows, to estimate their volumes, as well as to generate ground displacements maps, which were used to model the dikes that fed the eruptions. I then report on my work of the 2009 Harrat Lunayyir dike intrusion and the 2004 Tabuk earthquake sequence in western Saudi Arabia. I used InSAR observations and stress calculations to study the intruding dike at Harrat Lunayyir, while I combined InSAR data and Bayesian estimation to study the Tabuk earthquake activity. The key findings of the thesis are: 1) The recent volcanic eruptions in the southern Red Sea indicate that the area is magmatically more active than previously acknowledged and that a rifting episode has been taken place in the southern Red Sea; 2) Stress interactions between an ascending dike intrusion and normal faulting on graben-bounding faults above the dike can inhibit vertical propagation of magma towards the surface; 3) InSAR observations can improve locations of shallow earthquakes and fault model uncertainties are useful to associate earthquake activity with mapped faults; 4). The

  20. Soil gas 222Rn and volcanic activity at El Hierro (Canary Islands) before and after the 2011 submarine eruption

    Science.gov (United States)

    Padilla, G.; Hernández, P. A.; Padrón, E.; Barrancos, J.; Melián, G.; Dionis, S.; Rodríguez, F.; Nolasco, D.; Calvo, D.; Hernández, I.; Pereza, M. D.; Pérez, N. M.

    2012-04-01

    El Hierro (278 km2) is the southwesternmost island of the Canarian archipelago. From June 19, 2011 to January 2012, more than 11,950 seismic events have been detected by the seismic network of IGN. On 10 October 2011 the earthquake swarm changed its behaviour and produced a harmonic tremor due to magma movement, indicating that a submarine eruption located at 2 km south of La Restinga had started which is still in progress. Since 2003, the ITER Environmental Research Division now integrated in the Instituto Volcanológico de Canarias, INVOLCAN, has regularly performed soil gas surveys at El Hierro as a geochemical tool for volcanic surveillance. Among the investigated gases, soil gas radon (222Rn) and thoron (220Rn) have played a special attention. Both gases are characterized to ascend towards the surface mainly through cracks or faults via diffusion or advection, mechanisms dependent of both soil porosity and permeability, which in turn vary as a function of the stress/strain changes at depth. Years before the starts of the volcanic-seismic crisis on July 17, 2011, a volcanic multidisciplinary surveillance program was implemented at El Hierro including discrete and continuous measurements of 222Rn and 220Rn. Two soil gas 222Rn surveys had been carried out at El Hierro in 2003 and 2011, and four continuous geochemical monitoring stations for 222Rn and 220Rn measurements had been installed (HIE02, HIE03, HIE04 and HIE08). Soil gas 222Rn surveys were carried out at the surface environment of El Hierro after selecting 600 sampling observation sites (about 40 cm depth). Geochemical stations measure 222Rn and 220Rn activities by pumping the gas from a PVC pipe inserted 1m in the ground and thermally isolated. The results of the 2003 and 2011 soil gas 222Rn surveys show clearly a relatively higher observed 222Rn activities in the surface environment on 2011 than those observed on 2003 when no anomalous seismicity were taking place beneath El Hierro. The observed

  1. United States-Chile binational exchange for volcanic risk reduction, 2015—Activities and benefits

    Science.gov (United States)

    Pierson, Thomas C.; Mangan, Margaret T.; Lara Pulgar, Luis E.; Ramos Amigo, Álvaro

    2017-07-25

    In 2015, representatives from the United States and Chile exchanged visits to discuss and share their expertise and experiences dealing with volcano hazards. Communities in both countries are at risk from various volcano hazards. Risks to lives and property posed by these hazards are a function not only of the type and size of future eruptions but also of distances from volcanoes, structural integrity of volcanic edifices, landscape changes imposed by recent past eruptions, exposure of people and resources to harm, and any mitigative measures taken (or not taken) to reduce risk. Thus, effective risk-reduction efforts require the knowledge and consideration of many factors, and firsthand experience with past volcano crises provides a tremendous advantage for this work. However, most scientists monitoring volcanoes and most officials delegated with the responsibility for emergency response and management in volcanic areas have little or no firsthand experience with eruptions or volcano hazards. The reality is that eruptions are infrequent in most regions, and individual volcanoes may have dormant periods lasting hundreds to thousands of years. Knowledge may be lacking about how to best plan for and manage future volcanic crises, and much can be learned from the sharing of insights and experiences among counterpart specialists who have had direct, recent, or different experiences in dealing with restless volcanoes and threatened populations. The sharing of information and best practices can help all volcano scientists and officials to better prepare for future eruptions or noneruptive volcano hazards, such as large volcanic mudflows (lahars), which could affect their communities.

  2. Assessment of volcanic and geothermal activity in the Pasco Basin and vicinity

    International Nuclear Information System (INIS)

    Davis, J.D.

    1980-01-01

    Event network analyses indicate the most likely volcanic hazard to the Pasco Basin is influx of ash fall tephra from source areas in the Cascade Range. Less likely, but still notable, is the possibility of water flooding the Pasco Basin as a result of volcanic damming of one or more major drainages in the region. The least probable hazards include (1) influx of ash flows from eruptions in the Cascade Range or the Basin and Range Province, (2) renewed flood basalt volcanism, and (3) breaching of a repository by a dike or fissure. It is highly unlikely that volcanism will pose a direct threat to the integrity of any nuclear waste repositories in the Pasco Basin. Low-temperature geothermal water (20 degrees--90 degrees C) is present at random locations within the Pasco Basin and vicinity. This water may represent a potential resource only for direct heating purposes. Available data indicate no geothermal reservoirs with temperatures high enough and depths shallow enough for economical production of electricity are present within the Pasco Basin. 70 refs., 16 figs., 7 tabs

  3. Volcanic activity in Late Variscan Krkonoše Piedmont Basin: petrological and geochemical constraints

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Štěpánková, Jana; Novák, Jiří Karel; Pivec, Edvín; Prouza, V.

    2002-01-01

    Roč. 8, 3-4 (2002), s. 219-234 ISSN 1335-096X R&D Projects: GA AV ČR(CZ) IAA3013903 Keywords : Late Palaeozoic volcanism * Krkonoše Piedmont Basin * geochemistry Subject RIV: DB - Geology ; Mineralogy

  4. 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.

  5. 77 FR 31039 - Andean Trade Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication

    Science.gov (United States)

    2012-05-24

    .... 332-352, Andean Trade Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication... INTERNATIONAL TRADE COMMISSION [Investigation No. 332-352] Andean Trade Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication AGENCY: United States International Trade...

  6. Volcanic and Hydrothermal Activity of the North Su Volcano: New Insights from Repeated Bathymetric Surveys and ROV Observations

    Science.gov (United States)

    Thal, J.; Bach, W.; Tivey, M.; Yoerger, D.

    2013-12-01

    Bathymetric data from cruises in 2002, 2006, and 2011 were combined and compared to determine the evolution of volcanic activity, seafloor structures, erosional features and to identify and document the distribution of hydrothermal vents on North Su volcano, SuSu Knolls, eastern Manus Basin (Papua New Guinea). Geologic mapping based on ROV observations from 2006 (WHOI Jason-2) and 2011 (MARUM Quest-4000) combined with repeated bathymetric surveys from 2002 and 2011 are used to identify morphologic features on the slopes of North Su and to track temporal changes. ROV MARUM Quest-4000 bathymetry was used to develop a 10 m grid of the top of North Su to precisely depict recent changes. In 2006, the south slope of North Su was steeply sloped and featured numerous white smoker vents discharging acid sulfate waters. These vents were covered by several tens of meters of sand- to gravel-sized volcanic material in 2011. The growth of this new cone changed the bathymetry of the south flank of North Su up to ~50 m and emplaced ~0.014 km3 of clastic volcanic material. This material is primarily comprised of fractured altered dacite and massive fresh dacite as well as crystals of opx, cpx, olivine and plagioclase. There is no evidence for pyroclastic fragmentation, so we hypothesize that the fragmentation is likely related to hydrothermal explosions. Hydrothermal activity varies over a short (~50 m) lateral distance from 'flashing' black smokers to acidic white smoker vents. Within 2 weeks of observation time in 2011, the white smoker vents varied markedly in activity suggesting a highly episodic hydrothermal system. Based on ROV video recordings, we identified steeply sloping (up to 30°) slopes exposing pillars and walls of hydrothermal cemented volcaniclastic material representing former fluid upflow zones. These features show that hydrothermal activity has increased slope stability as hydrothermal cementation has prevented slope collapse. Additionally, in some places

  7. Martian volcanism: A review

    International Nuclear Information System (INIS)

    Carr, M.H.

    1987-01-01

    Martian volcanism is reviewed. It is emphasized that lava plains constitute the major type of effusive flow, and can be differentiated by morphologic characteristics. Shield volcanoes, domes, and patera constitute the major constructional landforms, and recent work has suggested that explosive activity and resulting pyroclastic deposits may have been involved with formation of some of the small shields. Analysis of morphology, presumed composition, and spectroscopic data all indicate that Martian volcanism was dominantly basaltic in composition

  8. Bee pollen as non-wood forest product in the eastern Andean highlands of Colombia

    Directory of Open Access Journals (Sweden)

    Fermín José Chamorro García

    2013-07-01

    Full Text Available The Andean forests of the Eastern Andean high-lands of Colombia have a high conservation priority given the vulnerable condition of species such as Quercus humboldtii (Fagaceae that inhabit these ecosystems. Beekeeping is regarded as an alternative activity that could play a role in the conservation of Andean forests, but little is known about how the floras of these ecosystems contribute to honey and bee pollen production. We analyzed the contribution of Andean forests to bee pollen production, given the productive potential and commercial importance of this product. Pollen analyses were performed on 25 samples from apiaries near Andean forests located in the states of Cundinamarca, Boyacá and Santander. We found that Q. humboldtii is an important source of pollen with high potential for monofloral bee pollen production. In addition, bees collect pollen from other Andean forests species such as Weinmannia tomentosa, Viburnum spp. and Morella spp. Utilization of bee pollen could lead to incentives to carry out forest conservation practices through beekeeping management.

  9. The climatic effect of explosive volcanic activity: Analysis of the historical data

    Science.gov (United States)

    Bryson, R. A.; Goodman, B. M.

    1982-01-01

    By using the most complete available records of direct beam radiation and volcanic eruptions, an historical analysis of the role of the latter in modulating the former was made. A very simple fallout and dispersion model was applied to the historical chronology of explosive eruptions. The resulting time series explains about 77 percent of the radiation variance, as well as suggests that tropical and subpolar eruptions are more important than mid-latitude eruptions in their impact on the stratospheric aerosol optical depth. The simpler climatic models indicate that past hemispheric temperature can be stimulated very well with volcanic and CO2 inputs and suggest that climate forecasting will also require volcano forecasting. There is some evidence that this is possible some years in advance.

  10. Magmatic activity beneath the quiescent Three Sisters volcanic center, central Oregon Cascade Range, USA

    Science.gov (United States)

    Wicks, Charles W.; Dzurisin, Daniel; Ingebritsen, Steven; Thatcher, Wayne; Lu, Zhong; Iverson, Justin

    2002-04-01

    Images from satellite interferometric synthetic aperture radar (InSAR) reveal uplift of a broad ~10 km by 20 km area in the Three Sisters volcanic center of the central Oregon Cascade Range, ~130 km south of Mt. St. Helens. The last eruption in the volcanic center occurred ~1500 years ago. Multiple satellite images from 1992 through 2000 indicate that most if not all of ~100 mm of observed uplift occurred between September 1998 and October 2000. Geochemical (water chemistry) anomalies, first noted during 1990, coincide with the area of uplift and suggest the existence of a crustal magma reservoir prior to the uplift. We interpret the uplift as inflation caused by an ongoing episode of magma intrusion at a depth of ~6.5 km.

  11. Localization of Volcanic Activity: Topographic Effects on Dike Propagation, Eruption and COnduit Formation

    Energy Technology Data Exchange (ETDEWEB)

    E.S. Gaffney; B. Damjanac

    2006-05-12

    Magma flow in a dike rising in a crack whose strike runs from a highland or a ridge to an adjacent lowland has been modeled to determine the effect of topography on the flow. It is found that there is a distinct tendency for the flow to be diverted away from the highland end of the strike toward the lowland. Separation of the geometric effect of the topography from its effect on lateral confining stresses on the crack indicates that both contribute to the effect but that the effect of stress is less important. Although this analysis explains a tendency for volcanic eruptions to occur in low lands, it does not preclude eruptions on highlands. The particular configuration modeled mimics topography around the proposed nuclear waste repository at Yucca Mountain, Nevada, so that the results may indicate some reduction in the volcanic hazard to the site.

  12. Localization of Volcanic Activity: Topographic Effects on Dike Propagation, Eruption and Conduit Formation

    International Nuclear Information System (INIS)

    E.S. Gaffney; B. Damjanac

    2006-01-01

    Magma flow in a dike rising in a crack whose strike runs from a highland or a ridge to an adjacent lowland has been modeled to determine the effect of topography on the flow. It is found that there is a distinct tendency for the flow to be diverted away from the highland end of the strike toward the lowland. Separation of the geometric effect of the topography from its effect on lateral confining stresses on the crack indicates that both contribute to the effect but that the effect of stress is less important. Although this analysis explains a tendency for volcanic eruptions to occur in low lands, it does not preclude eruptions on highlands. The particular configuration modeled mimics topography around the proposed nuclear waste repository at Yucca Mountain, Nevada, so that the results may indicate some reduction in the volcanic hazard to the site

  13. Enzyme activities and microbial indices of Mexican volcanic soils under different managements

    International Nuclear Information System (INIS)

    Pajares, S.; Gallardo, J. F.; Masciandaro, G.; Ceccanti, B.; Etchevers, J. D.; Marinari, S.

    2009-01-01

    Soils at the Mexican Trans-volcanic Belt are extremely important because the lack of agricultural land in overpopulated areas in Mexico. In addition, contents of soil organic matter (SOM) have been declining since the Mexican fields have been cultivated intensively. The aim of this work was to study how different agricultural management practices affect the SOM quality, using biochemical and microbiological parameters as indices. (Author)

  14. Estimation of age of Dali-Ganis rifting and associated volcanic activity, Venus

    Science.gov (United States)

    Basilevsky, A. T.

    1993-01-01

    This paper deals with the estimation of age for the Dali and Ganis Chasma rift zones and their associated volcanism based on photogeologic analysis of stratigraphic relations of rift-associated features with impact craters which have associated features indicative of their age. The features are radar-dark and parabolic, and they are believed to be mantles of debris derived from fallout of the craters' ejecta. They are thought to be among the youngest features on the Venusian surface, so their 'parent' craters must also be very young, evidently among the youngest 10 percent of Venus' crater population. Dali Chasma and Ganis Chasma are a part of a system of rift zones contained within eastern Aphrodite and Atla Regio which is a significant component of Venus tectonics. The rifts of this system are fracture belts which dissect typical Venusian plains with rare islands of tessera terrain. The rift zone system consists of several segments following each other (Diane, Dali, Ganis) and forming the major rift zone line, about 10,000 km long, which has junctions with several other rift zones, including Parga Chasma Rift. The junctions are usually locations of rift-associated volcanism in the form of volcanic edifices (Maat and Ozza Montes) or plain-forming flows flooding some areas within the rift zones and the adjacent plains.

  15. Eighteen years of geochemical monitoring at the oceanic active volcanic island of El Hierro (Canary Islands, Spain)

    Science.gov (United States)

    Asensio-Ramos, María; Alonso, Mar; Sharp, Emerson; Woods, Hannah; Barrancos, José; Pérez, Nemesio M.

    2016-04-01

    We report herein the latest results of a diffuse CO2 efflux survey at El Hierro volcanic system carried out during the summer period of 2015 to constrain the total CO2 output from the studied area a during post-eruptive period. El Hierro Island (278 km2) is the youngest and the SW-most of the Canary Islands. On July 16, 2011, a seismic-volcanic crisis started with the occurrence of more than 11,900 seismic events and significant deformation along the island. On October 10, 2011, the dominant character of seismicity changed dramatically from discrete earthquakes to continuous tremor, a clear indication that magma was rapidly approaching the surface immediately before the onset of the eruption, October 12. Eruption was declared over on 5 March, 2012. In order to monitor the volcanic activity of El Hierro Island, from 1998 to 2015 diffuse CO2 emission studies have been performed at El Hierro volcanic system in a yearly basis (˜600 observation sites) according to the accumulation chamber method. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. To quantify the total CO2 emission from the studied area, 100 simulations for each survey have been performed. During the eruption period, soil CO2 efflux values range from non-detectable (˜0.5 g m-2 d-1) up to 457 g m-2 d-1, reaching in November 27, 2011, the maximum CO2 output estimated value of all time series, 2,398 t d-1, just before the episodes of maximum degassing observed as vigorous bubbling at the sea surface and an increment in the amplitude of the tremor signal. During the 2015 survey, soil CO2 efflux values ranged from non-detectable up to 41 g m-2 d-1. The spatial distribution of diffuse CO2 emission values seemed to be controlled by the main volcano structural features of the island. The total diffuse CO2 output released to atmosphere was estimated at 575 ± 24 t d-1, value slightly higher that the background CO2 emission estimated at 422 t d-1 (Melián et

  16. Study of the structure changes caused by volcanic activity in Mexico applying the lineament analysis to the Aster (Terra) satellite data.

    Science.gov (United States)

    Arellano-Baeza, A. A.; Garcia, R. V.; Trejo-Soto, M.; Molina-Sauceda, E.

    Mexico is one of the most volcanically active regions in North America Volcanic activity in central Mexico is associated with the subduction of the Cocos and Rivera plates beneath the North American plate Periods of enhanced microseismic activity associated with the volcanic activity of the Colima and Popocapetl volcanoes are compared to some periods of low microseismic activity We detected changes in the number and orientation of lineaments associated with the microseismic activity due to lineament analysis of a temporal sequence of high resolution satellite images of both volcanoes 15 m resolution multispectral images provided by the ASTER VNIR instrument were used The Lineament Extraction and Stripes Statistic Analysis LESSA software package was employed for the lineament extraction

  17. Andean settlers rush for Amazonia.

    Science.gov (United States)

    Serra-vega, J

    1990-01-01

    Governments of Andean countries (Peru, Bolivia, Colombia, Ecuador, and Venezuela) have encouraged migration to the Amazon Basin, which has contributed to its destruction. Population pressure, landlessness, and poverty are the inducements to migrate. Efforts to populate the Amazon forest were begun as early as 1964 in Peru without international notice. By 1980, logging was allowed in Peru, and Brazil considered colonization of the Amazon essential to national sovereignty. By 1986, outside of Lima, Peru, a development project originally funded by the World Bank, the InterAmerican Development Bank, and the US, resulted in conflicts between settlers and Indians, in loggers indiscriminately cutting, and in farmers using slash and burn techniques to clear forests. Elsewhere the Peruvian Amazon, in San Ignacio, the population was growing by 5.5%/year. The jungle road that had been started but never completed, Carretera Marginal, destroyed 5 million hectares of primary forest, and much of the 600,000 hectares of arable land gained by the road suffered from inappropriate farming practices which caused massive erosion and laterization of the soils. Food crop production declined, and production of coca for cocaine increased. Coca crops are controlled by the Shining Path guerrillas, who are trying to overthrow the Peruvian government. Devastation of Ecuador around Lago Agrio continues. In Colombia, east of Bogota, forests have disappeared and hills have eroded and silted up rivers and dams. The Andean piedmont in Bolivia has also been devastated by loggers and by slash and burn farming. Southeastern Bolivian forests have been cleared for soya bean cultivation on poor soils. Social and economic crises propel people into the remaining forests. The solution is to ease foreign debt, transfer appropriate technology at affordable prices, refuse to finance destructive development, and help to educate and train scientific researchers. Family planning services are also urgently needed

  18. Toward a pro-active scientific advice on global volcanic activity within the multi-hazard framework of the EU Aristotle project

    Science.gov (United States)

    Barsotti, Sara; Duncan, Melanie; Loughlin, Susan; Gísladóttir, Bryndis; Roberts, Matthew; Karlsdóttir, Sigrún; Scollo, Simona; Salerno, Giuseppe; Corsaro, Rosa Anna; Charalampakis, Marinos; Papadopoulos, Gerassimos

    2017-04-01

    The demand for timely analysis and advice on global volcanic activity from scientists is growing. At the same time, decision-makers require more than an understanding of hazards; they need to know what impacts to expect from ongoing and future events. ARISTOTLE (All Risk Integrated System TOwards Trans-boundary hoListic Early-warning) is a two-year EC funded pilot project designed to do just that. The Emergency Response Coordination Centre (ERCC) works to support and coordinate response to disasters both inside and outside Europe using resources from the countries participating in the European Union Civil Protection Mechanism. Led by INGV and ZAMG, the ARISTOTLE consortium comprises 15 institutions across Europe and aims to deliver multi-hazard advice on natural events, including their potential interactions and impact, both inside and outside of Europe to the ERCC. Where possible, the ERCC would like a pro-active provision of scientific advice by the scientific group. Iceland Met Office leads the volcanic hazards work, with BGS, INGV and NOA comprising the volcano observatory team. At this stage, the volcanology component of the project comprises mainly volcanic ash and gas dispersal and potential impact on population and ground-based critical infrastructures. We approach it by relying upon available and official volcano monitoring institutions' reporting of activity, existing assessments and global databases of past events, modelling tools, remote-sensing observational systems and official VAAC advisories. We also make use of global assessments of volcanic hazards, country profiles, exposure and proxy indicators of threat to livelihoods, infrastructure and economic assets (e.g. Global Volcano Model outputs). Volcanic ash fall remains the only hazard modelled at the global scale. Volcanic risk assessments remain in their infancy, owing to challenges related to the multitude of hazards, data availability and model representation. We therefore face a number of

  19. Seismicity and volcanic activity in Japan based on crustal thermal activity. 1; Chikaku no netsukatsudo ni motozuku Nippon no jishin kazan katsudo. 1

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, M [Tokai Univ., Tokyo (Japan). School of Marine Science and Technology

    1996-05-01

    This paper describes the following matters about correlation between seismic and volcanic activities and thermal energy. Investigations on the status of seismic and volcanic activities in the Japanese archipelago during about 400 years in the past reveals the following matters: noticing earthquakes with magnitudes of upper M6 to about M7, flows of energy going outward from deep crust of the earth repeat ups and downs, whereas several prominent rising periods having certain time widths can be seen; volcanic activities are included in the rising period at the same rank as seismic activities; with regard to years 1900 and on, the similar fact can be seen if the Japanese archipelago is divided into a north portion, a south portion, and an extremely south portion southern than the Hiuga area; and the present time is going toward a period of rise in energy flows. In other words, it is thought that the crust and the uppermost portion of the mantle form one body like an organic body, making an action like a geyser releasing the energy outward. 3 refs., 2 figs., 1 tab.

  20. 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...... are isotopically similar to the Andean Southern Volcanic Zone arc rocks and their mantle source possibly resembled the source of South Atlantic N-MORB prior to addition of fluids and melts from the subduction channel. However, it must have been more enriched than the estimates of depleted upper mantle from...... the lithosphere is thinnest and possibly in areas of elevated mantle temperatures. The pyroxenite melts formed at deeper levels react with the surrounding peridotite and thereby changes composition leading to eruption of melts which experienced variable degrees of melt-peridotite interaction. This can presumably...

  1. Disruptive event analysis: volcanism and igneous intrusion

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1979-01-01

    Three basic topics are addressed for the disruptive event analysis: first, the range of disruptive consequences of a radioactive waste repository by volcanic activity; second, the possible reduction of the risk of disruption by volcanic activity through selective siting of a repository; and third, the quantification of the probability of repository disruption by volcanic activity

  2. Mesozooplankton distribution near an active volcanic island in the Andaman Sea (Barren Island)

    Digital Repository Service at National Institute of Oceanography (India)

    Pillai, H.U.K.; Jayaraj, K.A.; Rafeeq, M.; Jayalakshmi, K.J.; Revichandran, C.

    predation might happened in the surface. Copepods are important food items for chaetognaths (Liang and Vega-Pérez 1995), and they play an extremely important role in energy transfer to higher trophic levels (Terazaki 1998; Fulmer and Bollens 2005). It has... volcanic signature observed around Barren Island, Andaman Sea, India. Marine Geophysical Researches. doi:10.1007/ s11001–006–9008-z. Liang, T. H., & Vega-Pérez, L. A. (1995). Studies on chaetognaths off Ubatuba region, Brazil. II. Feeding habits...

  3. Opportunities for Monitoring Io's Volcanic Activity in the Visible and Infrared From JUICE - It's All About (Eruption) Style

    Science.gov (United States)

    Davies, Ashley; Matson, D.; McEwen, A. S.; Keszthelyi, L.

    2012-10-01

    The ESA Jupiter Icy Moons Explorer (JUICE) provides many opportunities for long-range monitoring of Io’s extraordinary silicate volcanic activity [1, 2]. A considerable amount of valuable work can be performed even with relatively low-spatial-resolution observations [2]. Techniques developed from the study of Galileo NIMS data and observations of terrestrial silicate volcanism allow the identification of likely eruption style [2] at many locations where the entire eruption is sub-pixel. Good temporal coverage, especially for episodic eruptions (including high-energy “outburst” eruptions), is important for modelling purposes. With opportunities to observe Io on a regular basis (hours-days) during cruise/orbital reduction phases, a visible-to-near-infrared mapping spectrometer (covering 0.4-5.5 µm) is the best instrument to chart the magnitude and variability of Io’s volcanic activity, allowing comparison with an existing and constantly expanding set of Io observations [e.g. 1, 3]. The eruption temperature of Io’s dominant silicate lava, a constraint on interior composition and conditions, is a major unanswered question in the wake of the Galileo mission [1]. A careful approach to instrument design is needed to ensure that observations by both imager and IR spectrometer on JUICE are capable of determining lava eruption temperature [e.g., 4] in low spatial resolution data. With an ideal thermal target (e.g., outburst eruption; the proposed lava lake at Pele) the imager should obtain multi-spectral data in a rapid sequence to allow stability of the thermal source to be quantified. Observations by imager and spectrometer have to be contemporaneous and unsaturated. References: [1] Davies, A. (2007) “Volcanism on Io”, Cam. Univ. Press. [2] Davies et al. (2010) JVGR, 194, 75-99. [3] Veeder et al. (2012) Icarus, 219, 701-722. [4] Davies et al. (2011) GRL, 38, L21308. This work was performed at the Jet Propulsion Laboratory-California Institute of Technology

  4. The Andean Geotrail (1): A scientific adventure

    Science.gov (United States)

    Sassier, C.; Galland, O.; Raufaste, C.; Mair, K.

    2009-12-01

    The role of Geosciences in our society is of primary importance. Its implications for humanity relate to major challenges such as climate change, managing energy resources, natural hazard mitigation, and water scarcity. Despite these issues being familiar to specialists, this is in general not the case for the public. In a world, where the impact of human activity is beginning to be seen on the environment, knowledge of the Earth and its history is paramount to make informed decisions that will influence our future. The necessity to educate the global population and raise awareness of Geosciences has led UNESCO to designate 2009 the International Year of the Planet Earth. In this context and with the label of the UNESCO, we organized and performed a popular science adventure that was followed in real time by both school children and many adults around the world. The Andean Geotrail consisted of a cycling expedition through a spectacular geological environment, the Andean Cordillera. During the nine month expedition, we cycled 8000 km and walked 400 km from Ushuaia in the Southern tip of Argentina to Nazca in Peru to encounter a rich variety of geological environments: active volcanoes, earthquakes, mineral and hydrocarbon deposits, and fantastic geological scenery. All this makes the Andes a great pedagogical natural laboratory. During the expedition, we visited spectacular geological localities that illustrate key Earth Science phenomena (such as mines and hydrocarbon deposits, erupting volcanoes and seismogenically active areas, and national parks) and discovered their implications for the local people. Along the way, we interviewed local geologists and scientists who helped us understand the geology of their areas. We gathered our own observations with those of the local specialists and published essays, articles and photographs on our website and blog (www.georouteandine.fr/English, http://georouteandine.blogspot.com). Seventeen schools in France and Norway

  5. Hazards of volcanic lakes: analysis of Lakes Quilotoa and Cuicocha, Ecuador

    Directory of Open Access Journals (Sweden)

    G. Gunkel

    2008-01-01

    Full Text Available Volcanic lakes within calderas should be viewed as high-risk systems, and an intensive lake monitoring must be carried out to evaluate the hazard of potential limnic or phreatic-magmatic eruptions. In Ecuador, two caldera lakes – Lakes Quilotoa and Cuicocha, located in the high Andean region >3000 a.s.l. – have been the focus of these investigations. Both volcanoes are geologically young or historically active, and have formed large and deep calderas with lakes of 2 to 3 km in diameter, and 248 and 148 m in depth, respectively. In both lakes, visible gas emissions of CO2 occur, and an accumulation of CO2 in the deep water body must be taken into account.

    Investigations were carried out to evaluate the hazards of these volcanic lakes, and in Lake Cuicocha intensive monitoring was carried out for the evaluation of possible renewed volcanic activities. At Lake Quilotoa, a limnic eruption and diffuse CO2 degassing at the lake surface are to be expected, while at Lake Cuicocha, an increased risk of a phreatic-magmatic eruption exists.

  6. Geosphere-biosphere interactions in bio-activity volcanic lakes: evidences from Hule and Rìo Cuarto (Costa Rica.

    Directory of Open Access Journals (Sweden)

    Jacopo Cabassi

    Full Text Available Hule and Río Cuarto are maar lakes located 11 and 18 km N of Poás volcano along a 27 km long fracture zone, in the Central Volcanic Range of Costa Rica. Both lakes are characterized by a stable thermic and chemical stratification and recently they were affected by fish killing events likely related to the uprising of deep anoxic waters to the surface caused by rollover phenomena. The vertical profiles of temperature, pH, redox potential, chemical and isotopic compositions of water and dissolved gases, as well as prokaryotic diversity estimated by DNA fingerprinting and massive 16S rRNA pyrosequencing along the water column of the two lakes, have highlighted that different bio-geochemical processes occur in these meromictic lakes. Although the two lakes host different bacterial and archaeal phylogenetic groups, water and gas chemistry in both lakes is controlled by the same prokaryotic functions, especially regarding the CO2-CH4 cycle. Addition of hydrothermal CO2 through the bottom of the lakes plays a fundamental priming role in developing a stable water stratification and fuelling anoxic bacterial and archaeal populations. Methanogens and methane oxidizers as well as autotrophic and heterotrophic aerobic bacteria responsible of organic carbon recycling resulted to be stratified with depth and strictly related to the chemical-physical conditions and availability of free oxygen, affecting both the CO2 and CH4 chemical concentrations and their isotopic compositions along the water column. Hule and Río Cuarto lakes were demonstrated to contain a CO2 (CH4, N2-rich gas reservoir mainly controlled by the interactions occurring between geosphere and biosphere. Thus, we introduced the term of bio-activity volcanic lakes to distinguish these lakes, which have analogues worldwide (e.g. Kivu: D.R.C.-Rwanda; Albano, Monticchio and Averno: Italy; Pavin: France from volcanic lakes only characterized by geogenic CO2 reservoir such as Nyos and Monoun

  7. 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.

  8. 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

  9. 3D-Reconstruction of recent volcanic activity from ROV-video, Charles Darwin Seamounts, Cape Verdes

    Science.gov (United States)

    Kwasnitschka, T.; Hansteen, T. H.; Kutterolf, S.; Freundt, A.; Devey, C. W.

    2011-12-01

    As well as providing well-localized samples, Remotely Operated Vehicles (ROVs) produce huge quantities of visual data whose potential for geological data mining has seldom if ever been fully realized. We present a new workflow to derive essential results of field geology such as quantitative stratigraphy and tectonic surveying from ROV-based photo and video material. We demonstrate the procedure on the Charles Darwin Seamounts, a field of small hot spot volcanoes recently identified at a depth of ca. 3500m southwest of the island of Santo Antao in the Cape Verdes. The Charles Darwin Seamounts feature a wide spectrum of volcanic edifices with forms suggestive of scoria cones, lava domes, tuff rings and maar-type depressions, all of comparable dimensions. These forms, coupled with the highly fragmented volcaniclastic samples recovered by dredging, motivated surveying parts of some edifices down to centimeter scale. ROV-based surveys yielded volcaniclastic samples of key structures linked by extensive coverage of stereoscopic photographs and high-resolution video. Based upon the latter, we present our workflow to derive three-dimensional models of outcrops from a single-camera video sequence, allowing quantitative measurements of fault orientation, bedding structure, grain size distribution and photo mosaicking within a geo-referenced framework. With this information we can identify episodes of repetitive eruptive activity at individual volcanic centers and see changes in eruptive style over time, which, despite their proximity to each other, is highly variable.

  10. Seismically active column and volcanic plumbing system beneath the island arc of the Izu-Bonin subduction zone

    Science.gov (United States)

    Špičák, Aleš; Vaněk, Jiří; Hanuš, Václav

    2009-12-01

    A detailed spatio-temporal analysis of teleseismic earthquake occurrence (mb > 4.0) along the convergent margin of the Izu-Bonin-Mariana arc system reveals an anomalously high concentration of events between 27° and 30.5°N, beneath a chain of seamounts between Tori-shima and Nishino-shima volcanoes. This seismicity is dominated by the 1985/1986 earthquake swarm represented in the Engdahl-van der Hilst-Buland database by 146 earthquakes in the body wave magnitude range 4.3-5.8 and focal depth range 1-100 km. The epicentral cluster of the swarm is elongated parallel to the volcanic chain. Available focal mechanisms are consistent with an extensional tectonic regime and reveal nodal planes with azimuths close to that of the epicentral cluster. Earthquakes of the 1985/1986 swarm occurred in seven time phases. Seismic activity migrated in space from one phase to the other. Earthquake foci belonging to individual phases of the swarm aligned in vertically disposed seismically active columns. The epicentral zones of the columns are located in the immediate vicinity of seamounts Suiyo and Mokuyo, recently reported by the Japanese Meteorological Agency as volcanically active. The three observations-episodic character of earthquake occurrence, column-like vertically arranged seismicity pattern, and existence of volcanic seamounts at the seafloor above the earthquake foci-led us to interpret the 1985/1986 swarm as a consequence of subduction-related magmatic and/or fluid activity. A modification of the shallow earthquake swarm magmatic model of D. Hill fits earthquake foci distribution, tectonic stress orientation and fault plane solutions. The 1985/1986 deep-rooted earthquake swarm in the Izu-Bonin region represents an uncommon phenomenon of plate tectonics. The portion of the lithospheric wedge that was affected by the swarm should be composed of fractured rigid, brittle material so that the source of magma and/or fluids which might induce the swarm should be situated at a

  11. Active spreading processes at ultraslow mid-ocean ridges: The 1999-2001 seismo-volcanic episode at 85°E Gakkel ridge, Arctic Ocean

    Science.gov (United States)

    Schlindwein, Vera; Riedel, Carsten; Korger, Edith; Läderach, Christine

    2010-05-01

    The rate of magma and crustal production at mid-ocean ridges is thought to decrease with decreasing spreading rate. At ultraslow spreading rates below 10-20 mm/y full rate, heat loss by conduction greatly reduces melt production with less melt produced at increasingly greater depths. Gakkel Ridge, the actively spreading mid-ocean ridge in the Arctic Ocean, opens at rates of 14 mm/y in the west decreasing to less than 6 mm/y at its eastern termination and demonstrates that magma production is not only a function of spreading rate. Whereas amagmatic spreading takes place at rates of about 12-10 mm/y, focussed melt production occurs at even lower spreading rates in long-lived discrete volcanic centres. One such centre is the 85°E volcanic complex at eastern Gakkel ridge where in 1999 a teleseismically recorded earthquake swarm consisting of more than 250 earthquakes over 9 months signalled the onset of an active spreading episode. The earthquake swarm is believed to be associated with volcanic activity although no concurrent lava effusion was found. We analysed the teleseismic earthquake swarm together with visual observation and microseismic data recorded at this site in 2001 and 2007 and noted the following characteristics which may be indicative for volcanic spreading events at the still poorly explored ultraslow spreading ridges: - unusual duration: The 1999 earthquake swarm lasted over 9 months rather than a few weeks as observed on faster spreading ridges. In addition, in 2001 seismoacoustic sounds which we interpret as gas discharge in Strombolian eruptions and a giant event plume maintained over more than one year indicate waxing and waning volcanic activity since 1999. - unusual strength: The earthquake swarm was detected at teleseismic distances of more than 1000 km and included 11 events with a magnitude >5. No other confirmed mid-ocean ridge eruption released a comparable seismic moment. Rather than focussing in a narrow area or showing pronounced

  12. Two new Cystoderma species from high Andean Ecuador

    DEFF Research Database (Denmark)

    Saar, I.; Læssøe, Thomas

    2006-01-01

    ABSTRACT: Two new agaric species, Cystoderma andinum and C. papallactae are described from high Andean Ecuador.......ABSTRACT: Two new agaric species, Cystoderma andinum and C. papallactae are described from high Andean Ecuador....

  13. Evidence from acoustic imaging for submarine volcanic activity in 2012 off the west coast of El Hierro (Canary Islands, Spain)

    Science.gov (United States)

    Pérez, Nemesio M.; Somoza, Luis; Hernández, Pedro A.; de Vallejo, Luis González; León, Ricardo; Sagiya, Takeshi; Biain, Ander; González, Francisco J.; Medialdea, Teresa; Barrancos, José; Ibáñez, Jesús; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

    2014-12-01

    We report precursory geophysical, geodetic, and geochemical signatures of a new submarine volcanic activity observed off the western coast of El Hierro, Canary Islands. Submarine manifestation of this activity has been revealed through acoustic imaging of submarine plumes detected on the 20-kHz chirp parasound subbottom profiler (TOPAS PS18) mounted aboard the Spanish RV Hespérides on June 28, 2012. Five distinct "filament-shaped" acoustic plumes emanating from the flanks of mounds have been recognized at water depth between 64 and 88 m on a submarine platform located NW El Hierro. These plumes were well imaged on TOPAS profiles as "flares" of high acoustic contrast of impedance within the water column. Moreover, visible plumes composed of white rafts floating on the sea surface and sourcing from the location of the submarine plumes were reported by aerial photographs on July 3, 2012, 5 days after acoustic plumes were recorded. In addition, several geophysical and geochemical data support the fact that these submarine vents were preceded by several precursory signatures: (i) a sharp increase of the seismic energy release and the number of daily earthquakes of magnitude ≥2.5 on June 25, 2012, (ii) significant vertical and horizontal displacements observed at the Canary Islands GPS network (Nagoya University-ITER-GRAFCAN) with uplifts up to 3 cm from June 25 to 26, 2012, (iii) an anomalous increase of the soil gas radon activity, from the end of April until the beginning of June reaching peak values of 2.7 kBq/m3 on June 3, 2012, and (iv) observed positive peak in the air-corrected value of 3He/4He ratio monitored in ground waters (8.5 atmospheric 3He/4He ratio ( R A)) at the northwestern El Hierro on June 16, 2012. Combining these submarine and subaerial information, we suggest these plumes are the consequence of submarine vents exhaling volcanic gas mixed with fine ash as consequence of an event of rapid rise of volatile-rich magma beneath the NW submarine ridge

  14. Andean tectonics: Implications for Satellite Geodesy

    Science.gov (United States)

    Allenby, R. J.

    1984-01-01

    Current knowledge and theories of large scale Andean tectonics as they relate to site planning for the NASA Crustal Dynamics Program's proposed high precision geodetic measurements of relative motions between the Nazca and South American plates are summarized. The Nazca Plate and its eastern margin, the Peru-Chile Trench, is considered a prototype plate marked by rapid motion, strong seismicity and well defined boundaries. Tectonic activity across the Andes results from the Nazca Plate subducting under the South American plate in a series of discrete platelets with different widths and dip angles. This in turn, is reflected in the tectonic complexity of the Andes which are a multitutde of orogenic belts superimposed on each other since the Precambrian. Sites for Crustal Dynamics Program measurements are being located to investigate both interplate and extraplate motions. Observing operations have already been initiated at Arequipa, Peru and Easter Island, Santiago and Cerro Tololo, Chile. Sites under consideration include Iquique, Chile; Oruro and Santa Cruz, Bolivia; Cuzco, Lima, Huancayo and Bayovar, Peru; and Quito and the Galapagos Islands, Ecuador. Based on scientific considerations, Santa Cruz, Huancayo (or Lima), Quito and the Galapagos Islands should be replaced by Isla San Felix, Chile; Brazilia or Petrolina, Brazil; and Guayaquil, Ecuador. If resources permit, additional important sites would be Buenaventura and Villavicencio or Puerto La Concordia, Colombia; and Mendoza and Cordoba, Argentina.

  15. Fluid escape structures in the Graham Bank region (Sicily Channel, Central Mediterranean) revealing volcanic and neotectonic activity.

    Science.gov (United States)

    Spatola, Daniele; Pennino, Valentina; Basilone, Luca; Interbartolo, Francesco; Micallef, Aaron; Sulli, Attilio; Basilone, Walter

    2016-04-01

    In the Sicily Channel, (Central Mediterranean), two geodynamic processes overlap each other, the Maghrebides-Apennines accretionary prism and the Sicily Channel rift. Moreover, the northwestern sector (Banks sector) is characterised by an irregular seafloor morphology linked to the recent volcanic and tectonic activity.In order to discriminate the role exerted by both the processes in the morphostructural setting of the area we used a dataset of both high and very high resolution single-channel and multi-channel profiles, acquired in the frame of the RITMARE project respectively with CHIRP and sparker, and airgun sources, and high resolution (5 m cell) morpho-bathymetric data. The data allowed us to identify and characterise two areas where different geological features (sedimentary and volcanic) are prevailing. They present fluid escaping evidence, which often appears to be active and generating different types of morphologies (both positive and negative). In the western sector we recognised pockmarks at water depths of 195 to 317 m, with diameters from 25 to 580 m, depths from 1.3 to 15 m, and slope up to 23°. They show sub-circular shape in plan-view and reflectors with upward concavity in cross section, and are oriented along a NW-SE trend.The CHIRP and multichannel profiles highlight fluids that affect the Plio-Quaternary succession, especially in areas where the top surface of the Messinian succession is shallower. Conversely, wipe-out acoustic facies were recognised in proximity of: i) extensional faults of Mesozoic age with NW-SE trend; ii) dip/strike slip faults of Cenozoic age with NW-SE, N-S and about NNE-SSW trends, and iii) extensional neo-tectonic faults with NW-SE and NNW-SSE trends. We cannot exclude that they could feed the shallower reservoir producing a mixing between the two. In the eastern sector we recognised a cluster of volcanoes composed of seven cone-shaped structures (SCV1-7), pertaining to a wide area known as Graham Bank. A detailed

  16. Volcview: A Web-Based Platform for Satellite Monitoring of Volcanic Activity and Eruption Response

    Science.gov (United States)

    Schneider, D. J.; Randall, M.; Parker, T.

    2014-12-01

    The U.S. Geological Survey (USGS), in cooperation with University and State partners, operates five volcano observatories that employ specialized software packages and computer systems to process and display real-time data coming from in-situ geophysical sensors and from near-real-time satellite sources. However, access to these systems both inside and from outside the observatory offices are limited in some cases by factors such as software cost, network security, and bandwidth. Thus, a variety of Internet-based tools have been developed by the USGS Volcano Science Center to: 1) Improve accessibility to data sources for staff scientists across volcano monitoring disciplines; 2) Allow access for observatory partners and for after-hours, on-call duty scientists; 3) Provide situational awareness for emergency managers and the general public. Herein we describe VolcView (volcview.wr.usgs.gov), a freely available, web-based platform for display and analysis of near-real-time satellite data. Initial geographic coverage is of the volcanoes in Alaska, the Russian Far East, and the Commonwealth of the Northern Mariana Islands. Coverage of other volcanoes in the United States will be added in the future. Near-real-time satellite data from NOAA, NASA and JMA satellite systems are processed to create image products for detection of elevated surface temperatures and volcanic ash and SO2 clouds. VolcView uses HTML5 and the canvas element to provide image overlays (volcano location and alert status, annotation, and location information) and image products that can be queried to provide data values, location and measurement capabilities. Use over the past year during the eruptions of Pavlof, Veniaminof, and Cleveland volcanoes in Alaska by the Alaska Volcano Observatory, the National Weather Service, and the U.S. Air Force has reinforced the utility of shared situational awareness and has guided further development. These include overlay of volcanic cloud trajectory and

  17. Improved techniques in data analysis and interpretation of potential fields: examples of application in volcanic and seismically active areas

    Directory of Open Access Journals (Sweden)

    G. Florio

    2002-06-01

    Full Text Available Geopotential data may be interpreted by many different techniques, depending on the nature of the mathematical equations correlating specific unknown ground parameters to the measured data set. The investigation based on the study of the gravity and magnetic anomaly fields represents one of the most important geophysical approaches in the earth sciences. It has now evolved aimed both at improving of known methods and testing other new and reliable techniques. This paper outlines a general framework for several applications of recent techniques in the study of the potential methods for the earth sciences. Most of them are here described and significant case histories are shown to illustrate their reliability on active seismic and volcanic areas.

  18. Global positioning system survey data for active seismic and volcanic areas of eastern Sicily, 1994 to 2013

    Science.gov (United States)

    Bonforte, Alessandro; Fagone, Sonia; Giardina, Carmelo; Genovese, Simone; Aiesi, Gianpiero; Calvagna, Francesco; Cantarero, Massimo; Consoli, Orazio; Consoli, Salvatore; Guglielmino, Francesco; Puglisi, Biagio; Puglisi, Giuseppe; Saraceno, Benedetto

    2016-08-01

    This work presents and describes a 20-year long database of GPS data collected by geodetic surveys over the seismically and volcanically active eastern Sicily, for a total of more than 6300 measurements. Raw data were initially collected from the various archives at the Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania—Osservatorio Etneo and organized in a single repository. Here, quality and completeness checks were performed, while all necessary supplementary information were searched, collected, validated and organized together with the relevant data. Once all data and information collections were completed, raw binary data were converted into the universal ASCII RINEX format; all data are provided in this format with the necessary information for precise processing. In order to make the data archive readily consultable, we developed software allowing the user to easily search and obtain the needed data by simple alphanumeric and geographic queries.

  19. Global positioning system survey data for active seismic and volcanic areas of eastern Sicily, 1994 to 2013.

    Science.gov (United States)

    Bonforte, Alessandro; Fagone, Sonia; Giardina, Carmelo; Genovese, Simone; Aiesi, Gianpiero; Calvagna, Francesco; Cantarero, Massimo; Consoli, Orazio; Consoli, Salvatore; Guglielmino, Francesco; Puglisi, Biagio; Puglisi, Giuseppe; Saraceno, Benedetto

    2016-08-01

    This work presents and describes a 20-year long database of GPS data collected by geodetic surveys over the seismically and volcanically active eastern Sicily, for a total of more than 6300 measurements. Raw data were initially collected from the various archives at the Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania-Osservatorio Etneo and organized in a single repository. Here, quality and completeness checks were performed, while all necessary supplementary information were searched, collected, validated and organized together with the relevant data. Once all data and information collections were completed, raw binary data were converted into the universal ASCII RINEX format; all data are provided in this format with the necessary information for precise processing. In order to make the data archive readily consultable, we developed software allowing the user to easily search and obtain the needed data by simple alphanumeric and geographic queries.

  20. Long-term volcanic hazard forecasts based on Somma-Vesuvio past eruptive activity

    Science.gov (United States)

    Lirer, Lucio; Petrosino, Paola; Alberico, Ines; Postiglione, Immacolata

    2001-02-01

    Distributions of pyroclastic deposits from the main explosive events at Somma-Vesuvio during the 8,000-year B.P.-A.D. 1906 time-span have been analysed to provide maps of volcanic hazard for long-term eruption forecasting. In order to define hazard ratings, the spatial distributions and loads (kg/m2) exerted by the fall deposits on the roofs of buildings have been considered. A load higher than 300 kg/m2 is defined as destructive. The relationship load/frequency (the latter defined as the number of times that an area has been impacted by the deposition of fall deposits) is considered to be a suitable parameter for differentiating among areas according to hazard rating. Using past fall deposit distributions as the basis for future eruptive scenarios, the total area that could be affected by the products of a future Vesuvio explosive eruption is 1,500 km2. The perivolcanic area (274 km2) has the greatest hazard rating because it could be buried by pyroclastic flow deposits thicker than 0.5 m and up to several tens of metres in thickness. Currently, the perivolcanic area also has the highest risk because of the high exposed value, mainly arising from the high population density.

  1. 75 FR 24967 - Andean Trade Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication

    Science.gov (United States)

    2010-05-06

    ... Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication. DATES: June 24, 2010... INTERNATIONAL TRADE COMMISSION [Investigation No. 332-352] Andean Trade Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication AGENCY: United States International Trade...

  2. Characterization of the volcanic eruption emissions using neutron activation analysis; Caracterizacion de las emisiones de una erupcion volcanica mediante analisis por activacion neutronica

    Energy Technology Data Exchange (ETDEWEB)

    Pla, Rita R. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Radioquimica, Tecnicas Analiticas Nucleares; Tafuri, Victoria V. [Servicio Meteorologico Nacional, Buenos Aires (Argentina). Centro de Contaminacion del Aire

    1997-10-01

    Characterization of the volcanic particulate material has been performed by analyzing aerosols and ashes with instrumental neutron activation analysis. Crustal enrichment factors were calculated using the elemental concentration and clustering techniques, and multivariate analysis were done. The analytical and data treatment methodologies allowed the sample differentiation from their geographical origin viewpoint, based on their chemical composition patterns, which are related to the deposit formation processes, which consist of direct deposition from the volcanic cloud, and removal by wind action after the end of the eruption, and and finally the deposition. (author). 8 refs., 5 figs.

  3. Forms of memory in Andean queros

    Directory of Open Access Journals (Sweden)

    Alfredo Cordiviola

    2017-12-01

    Full Text Available In colonial times, queros were used to drink chicha and to formalize pacts in ritual ceremonies by the indigenous Andean elites. They had been manufactured for centuries, long before the Incas dominated the region, and continued to be made after Spanish domination and compulsory evangelization had been established. During the Inca empire, the surface of the queros was covered just with incisions and geometric forms; in the viceroyalty of Peru they were covered instead with figurative images. In this work we analyze the evolution of these forms and the different ways in which these ceremonial vessels were used to evoke the Andean pasts.

  4. Possible Late Pleistocene volcanic activity on Nightingale Island, South Atlantic Ocean, based on geoelectrical resistivity measurements, sediment corings and 14C dating

    DEFF Research Database (Denmark)

    Bjørk, Anders Anker; Björck, Svante; Cronholm, Anders

    2011-01-01

    . The irregular shapes of the basins and the lack of clear erosional features indicate that they are not eruption craters and were not formed by erosion. Instead, we regard them as morphological depressions formed between ridges of trachytic lava flows and domes at a late stage of the formation of the volcanic...... edifice. The onset of sedimentation within these basins appears to have occurred between 24 and 37 ka with the highest situated wetland yielding the highest ages. These ages are very young compared to the timing of the main phase of the formation of the island, implying volcanic activity on the island......Tristan da Cunha is a volcanic island group situated in the central South Atlantic. The oldest of these islands, Nightingale Island, has an age of about 18Ma. In the interior of the island, there are several wetlands situated in topographic depressions. The ages of these basins have been unknown...

  5. Sediment budget in the Ucayali River basin, an Andean tributary of the Amazon River

    Directory of Open Access Journals (Sweden)

    W. Santini

    2015-03-01

    Full Text Available Formation of mountain ranges results from complex coupling between lithospheric deformation, mechanisms linked to subduction and surface processes: weathering, erosion, and climate. Today, erosion of the eastern Andean cordillera and sub-Andean foothills supplies over 99% of the sediment load passing through the Amazon Basin. Denudation rates in the upper Ucayali basin are rapid, favoured by a marked seasonality in this region and extreme precipitation cells above sedimentary strata, uplifted during Neogene times by a still active sub-Andean tectonic thrust. Around 40% of those sediments are trapped in the Ucayali retro-foreland basin system. Recent advances in remote sensing for Amazonian large rivers now allow us to complete the ground hydrological data. In this work, we propose a first estimation of the erosion and sedimentation budget of the Ucayali River catchment, based on spatial and conventional HYBAM Observatory network.

  6. Administrative Law in the Andean Community of Nations

    Directory of Open Access Journals (Sweden)

    Jorge Enrique Santos Rodríguez

    2013-12-01

    Full Text Available One of the contemporary tendencies of Administrative Law is the recognition of its existence beyond the borders of a State. Under such premise, this paper aims to demonstrate that in the Andean Community of Nations sufficient elements to consider the existence of an Andean administrative Law. In the Andean statutes and rules, it is possible to identify an administrative function, as well as an administrative organization inside the Andean Integration System; and a system of Andean administrative rules and an administrative justice system.

  7. Transition from phreatic to phreatomagmatic explosive activity of Zhupanovsky volcano (Kamchatka) in 2013-2016 due to volcanic cone collapse

    Science.gov (United States)

    Gorbach, Natalia; Plechova, Anastasiya; Portnyagin, Maxim

    2017-04-01

    Zhupanovsky volcano, situated 70 km north from Petropavlovsk-Kamchatsky city, resumed its activity in October 2013 [3]. In 2014 and in the first half of 2015, episodic explosions with ash plumes rising up to 6-8 km above sea level occurred on Priemish cone - one of four cones on the Zhupanovsky volcanic edifice [1]. In July 2015 after a series of seismic and explosive events, the southern sector of the active cone collapsed. The landslide and lahar deposits resulted from the collapse formed a large field on the volcano slopes [2]. In November 2015 and January-March 2016, a series of powerful explosions took place sending ash up to 8-10 km above sea level. No pure magmatic, effusive or extrusive, activity has been observed on Zhupanovsky in 2013-2016. We have studied the composition, morphology and textural features of ash particles produced by the largest explosive events of Zhupanovsky in the period from October 2013 to March 2016. The main components of the ash were found to be hydrothermally altered particles and lithics, likely originated by the defragmentation of rocks composing the volcanic edifice. Juvenile glass fragments occur in very subordinate quantities. The maximum amount of glass particles (up to 7%) was found in the ash erupted in January-March 2016, after the cone collapse. We suggest that the phreatic to phreatomagmatic explosive activity of Zhupanovsky volcano in 2013-2016 was initially caused by the intrusion of a new magma batch under the volcano. The intrusion and associated degassing of magma led to heating, overpressure and instability in the hydrothermal system of the volcano, causing episodic, predominantly phreatic explosions. Decompression of the shallow magmatic and hydrothermal system of the volcano due to the cone collapse in July 2015 facilitated a larger involvement of the magmatic component in the eruption and more powerful explosions. [1] Girina O.A. et al., 2016 Geophysical Research Abstracts Vol. 18, EGU2016-2101, doi: 10

  8. Low-pressure evolution of arc magmas in thickened crust: The San Pedro-Linzor volcanic chain, Central Andes, Northern Chile

    Science.gov (United States)

    Godoy, Benigno; Wörner, Gerhard; Kojima, Shoji; Aguilera, Felipe; Simon, Klaus; Hartmann, Gerald

    2014-07-01

    Magmatism at Andean Central Volcanic Zone (CVZ), or Central Andes, is strongly influenced by differentiation and assimilation at high pressures that occurred at lower levels of the thick continental crust. This is typically shown by high light to heavy rare earth element ratios (LREE/HREE) of the erupted lavas at this volcanic zone. Increase of these ratios with time is interpreted as a change to magma evolution in the presence of garnet during evolution of Central Andes. Such geochemical signals could be introduced into the magmas be high-pressure fractionation with garnet on the liquidus and/or assimilation from crustal rocks with a garnet-bearing residue. However, lavas erupted at San Pedro-Linzor volcanic chain show no evidence of garnet fractionation in their trace element patterns. This volcanic chain is located in the active volcanic arc, between 22°00‧S and 22°30‧S, over a continental crust ˜70 km thick. Sampled lavas show Sr/Y and Sm/Yb ratios Chile. We relate our geochemical observations to shallow crustal evolution of primitive magmas involving a high degree of assimilation of upper continental crust. We emphasize that low pressure AFC- (Assimilation Fractional Crystallization) type evolution of the San Pedro-Linzor volcanic chain reflects storage, fractionation, and contamination of mantle-derived magmas at the upper felsic crust (<40 km depth). The ascent of mantle-derived magmas to mid-crustal levels is related with the extensional regime that has existed in this zone of arc-front offset since Late-Miocene age, and the relatively thin portion of mafic lower crust observed below the volcanic chain.

  9. Andean cutaneous leishmaniasis (Andean-CL, uta) in Peru and Ecuador: the vector Lutzomyia sand flies and reservoir mammals.

    Science.gov (United States)

    Hashiguchi, Yoshihisa; Gomez L, Eduardo A; Cáceres, Abraham G; Velez, Lenin N; Villegas, Nancy V; Hashiguchi, Kazue; Mimori, Tatsuyuki; Uezato, Hiroshi; Kato, Hirotomo

    2018-02-01

    The vector Lutzomyia sand flies and reservoir host mammals of the Leishmania parasites, causing the Andean cutaneous leishmaniasis (Andean-CL, uta) in Peru and Ecuador were thoroughly reviewed, performing a survey of literatures including our unpublished data. The Peruvian L. (V.) peruviana, a principal Leishmania species causing Andean-CL in Peru, possessed three Lutzomyia species, Lu. peruensis, Lu. verrucarum and Lu. ayacuchensis as vectors, while the Ecuadorian L. (L.) mexicana parasite possessed only one species Lu. ayacuchensis as the vector. Among these, the Ecuadorian showed a markedly higher rate of natural Leishmania infections. However, the monthly and diurnal biting activities were mostly similar among these vector species was in both countries, and the higher rates of infection (transmission) reported, corresponded to sand fly's higher monthly-activity season (rainy season). The Lu. tejadai sand fly participated as a vector of a hybrid parasite of L. (V.) braziliensis/L. (V.) peruviana in the Peruvian Andes. Dogs were considered to be principal reservoir hosts of the L. (V.) peruviana and L. (L.) mexicana parasites in both countries, followed by other sylvatic mammals such as Phyllotis andium, Didelphis albiventris and Akodon sp. in Peru, and Rattus rattus in Ecuador, but information on the reservoir hosts/mammals was extremely poor in both countries. Thus, the Peruvian disease form demonstrated more complicated transmission dynamics than the Ecuadorian. A brief review was also given to the control of vector and reservoirs in the Andes areas. Such information is crucial for future development of the control strategies of the disease. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. High-up: a remote reservoir of microbial extremophiles at Central Andean Wetlands

    Directory of Open Access Journals (Sweden)

    Virginia Helena Albarracín

    2015-12-01

    Full Text Available The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3,700 m. Being isolated and hostile, these so-called High-Altitude Andean Lakes (HAAL are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern -though quite imperfect- analogues of environments proxy for an earlier time in Earth’s history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure. Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e. DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes.

  11. Preliminary review and summary of the potential for tectonic, seismic, and volcanic activity at the Nevada Test Site defense waste disposal site

    International Nuclear Information System (INIS)

    Metcalf, L.A.

    1983-03-01

    A change from compressional to extensional tectonics, which occurred about 17 m.y. ago, marks the emergence of the present tectonic regime in the southern Great Basin. Crustal extension is continuing at the present time, oriented in a NW-SE direction in the NTS region. Concurrently with the onset of crustal extension a system of NW- and NE-trending shear zones developed, along which mutual offset has occurred. Present seismic and tectonic activity in the NTS region is concentrated along the intersections of the shear zones and in areas of deep basin formation. Natural historic seismicity of the NTS region has been low to moderate. Seismic hazard assessments suggest a maximum magnitude 6-7 earthquake, associated with a maximum peak acceleration of 0.7 to 0.9 g, is probable for the NTS. A return period of 12,700 to 15,000 y for the maximum peak acceleration indicates a relatively low seismic hazard. Silicic volcanism in the NTS region was active from 16 to 6 m.y. ago, followed by a transition to basaltic volcanism. The tectonic settings most favorable for Quaternary basaltic activity are areas of young basin-range extension, caldera ring fracture zones, and intersections of conjugate shear zones. Probability calculations for the Yucca Mountain waste repository result in a volcanic disruption hazard of 10 - 8 to 10 - 9 /y. This value is extremely low and is probably representative of the hazard at Frenchman Flat. However, due to its tectonic setting, Frenchman Flat may be an area conducive to future basaltic volcanism; further investigation is needed to properly assess volcanic hazard

  12. Volcanic eruption plumes on Io

    International Nuclear Information System (INIS)

    Strom, R.G.; Terrile, R.J.; Masursky, H.; Hansen, C.

    1979-01-01

    The detection of an umbrella-shaped plume extending about 280 km above the bright limb of Io was one of the most important discoveries made during the Voyager 1 encounter with the jovian system. This discovery proves that Io is volcanically active at present, and the number and magnitude of these eruptions indicate that Io is the most volcanically active body so far discovered in the Solar System. Preliminary analyses of these eruptive plumes are presented. (U.K.)

  13. Disruptive event analysis: volcanism and igneous intrusion

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1980-08-01

    An evaluation is made of the disruptive effects of volcanic activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by volcanic activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future volcanic activity. And third, can the probability of repository disruption by volcanic activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by volcanic activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of volcanism. Potential radionuclide dispersal by volcanic transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or volcanic provinces within the western United States have been sites of significant volcanism and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active volcanism are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of volcanic activity and a numerical evaluation of the areal extent of volcanic disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past volcanic activity

  14. The fabrication of andean particularism

    Directory of Open Access Journals (Sweden)

    1989-01-01

    original culture through resistance, it focuses on the fabrication of tradition within the disciplinary strategies of the colonial order and on the local re-employment of those productions in political mobilizations. The discussion of this major issue within the field of Andean history is undertaken against the horizon of a case of resistance focusing on the Inca from the Audiencia of Quito in the seventeenth century. Such an incident affords a privileged field for the investigation of the connections between colonial authority and origins, since it stages the recall, simulation and reinstatement of the past.

  15. Seismicity and volcanic activity in Japan based on crustal thermal activity . 2; Chikaku no netsukatsudo ni motozuku Nippon no Jishin kazan katsudo. 2

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, M [Tokai Univ., Tokyo (Japan). School of Marine Science and Technology

    1996-05-01

    This paper describes the following matters about seismic and volcanic activities in Japan. The previous paper has reported a view that energy is transported from deep portions of the earth`s crust toward outer portions, and the stored energy thrusts up collectively in a certain time period (a rising period). A fact may be accounted for as one of the endorsements thereof that earthquakes and volcanic eruptions take place successively over a wide area from Okinawa to Hokkaido in a short period of time (included in the rising period). When viewed by limiting the time period and areas, a great earthquake would not occur suddenly, but stored energy is released wholly at a certain time while it has been released little by little. Referring to the Kanto Great Earthquake (1923) and the Tokai and Nankai Earthquakes (1944 and 1946), it is found that earthquakes had been occurring successively in the surrounding areas since about 20 years before the occurrence of these great earthquakes. Similar phenomena may be seen in the great earthquakes of Ansei (1854) and An-ei (1707). 5 figs.

  16. 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

  17. Evidence of Influence of Human Activities and Volcanic Eruptions on Environmental Perchlorate from a 300-Year Greenland Ice Core Record.

    Science.gov (United States)

    Cole-Dai, Jihong; Peterson, Kari Marie; Kennedy, Joshua Andrew; Cox, Thomas S; Ferris, David G

    2018-06-26

    A 300-year (1700-2007) chronological record of environmental perchlorate, reconstructed from high-resolution analysis of a central Greenland ice core, shows that perchlorate levels in the post-1980 atmosphere were two-to-three times those of the pre-1980 environment. While this confirms recent reports of increased perchlorate in Arctic snow since 1980 compared with the levels for the prior decades (1930-1980), the longer Greenland record demonstrates that the Industrial Revolution and other human activities, which emitted large quantities of pollutants and contaminants, did not significantly impact environmental perchlorate, as perchlorate levels remained stable throughout the eighteenth, nineteenth, and much of the twentieth centuries. The increased levels since 1980 likely result from enhanced atmospheric perchlorate production, rather than from direct release from perchlorate manufacturing and applications. The enhancement is probably influenced by the emission of organic chlorine compounds in the last several decades. Prior to 1980, no significant long-term temporal trends in perchlorate concentration are observed. Brief (a few years) high concentration episodes appear frequently over an apparently stable and low background (~1 ng kg‒1). Several such episodes coincide in time with large explosive volcanic eruptions including the 1912 Novarupta/Katmai eruption in Alaska. It appears that atmospheric perchlorate production is impacted by large eruptions in both high and low latitudes, but not by small eruptions and non-explosive degassing.

  18. Volcanic eruptions on Io

    Science.gov (United States)

    Strom, R. G.; Schneider, N. M.; Terrile, R. J.; Hansen, C.; Cook, A. F.

    1981-01-01

    Nine eruption plumes which were observed during the Voyager 1 encounter with Io are discussed. During the Voyager 2 encounter, four months later, eight of the eruptions were still active although the largest became inactive sometime between the two encounters. Plumes range in height from 60 to over 300 km with corresponding ejection velocities of 0.5 to 1.0 km/s and plume sources are located on several plains and consist of fissures or calderas. The shape and brightness distribution together with the pattern of the surface deposition on a plume 3 is simulated by a ballistic model with a constant ejection velocity of 0.5 km/s and ejection angles which vary from 0-55 deg. The distribution of active and recent eruptions is concentrated in the equatorial regions and indicates that volcanic activity is more frequent and intense in the equatorial regions than in the polar regions. Due to the geologic setting of certain plume sources and large reservoirs of volatiles required for the active eruptions, it is concluded that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.

  19. Provenance and fate of arsenic and other solutes in the Chaco-Pampean Plain of the Andean foreland, Argentina: From perspectives of hydrogeochemical modeling and regional tectonic setting

    Science.gov (United States)

    Raychowdhury, Nilasree; Mukherjee, Abhijit; Bhattacharya, Prosun; Johannesson, Karen; Bundschuh, Jochen; Sifuentes, Gabriela Bejarano; Nordberg, Erika; Martin, Raúl A.; Storniolo, Angel del Rosario

    2014-10-01

    Extensive arsenic (As) enriched groundwater is known to occur in the aquifers of the Chaco-Pampean Plain of Argentina. Previous studies speculated that the As mobilization in these groundwaters was a direct result of their elevated pH and oxidative conditions. The volcanic glass layers present in the aquifer matrix were hypothesized as one of the possible sources of As to the groundwaters. Here, we examine the groundwater chemistry of the Santiago del Estero province of Chaco-Pampean Plains of Argentina, and test these hypotheses by using hydrogeochemical modeling within the framework of the regional geologic-tectonic setting. The study area is located in the active foreland of the Andean orogenic belt, which forms a continental arc setting, and is dotted with several hot springs. Rhyolitic volcanic glass fragments derived from arc volcanism are abundant within the aeolian-fluvial aquifer sediments, and are related to the paleo-igneous extrusion in the vicinity. Hydrogeochemical analyses show that the groundwater is in predominantly oxidative condition. In addition, some of the groundwaters exhibit very high Na, Cl- and SO42- concentrations. It is hypothesized in this study that the groundwater chemistry has largely evolved by dissolution of rhyolitic volcanic glass fragments contained within the aquifer sediments along with mixing with saline surface waters from, adjoining salinas, which are thought to be partially evaporated remnants of a paleo inland sea. Flow path modeling, stability diagrams, and thermodynamic analyses undertaken in this study indicate that the dominant evolutionary processes include ion exchange reactions, chemical weathering of silicate and evaporites, in monosialitization-dominated weathering. Geochemical modeling predicts that plagioclase feldspar and volcanic glass are the major solids phases that contribute metal cations and dissolved silica to the local groundwaters. Co-influxed oxyanions, with similar ionic radii and structure (e.g. Mo

  20. 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

  1. 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.

  2. The Andean Swallow (Orochelidon andecola) in Argentina

    OpenAIRE

    Mazar Barnett, Juan; Pugnali, Germán D.; Pearman Morrison, Mark; Bodrati, Alejandro; Moschione, Flavio; Clark, Ricardo; Roesler, Carlos Ignacio; Monteleone, Diego; Casañas, Hernán; Burgos Gallardo, Freddy; Segovia, José; Pagano, Luis; Povedano, Hernán; Areta, Juan Ignacio

    2016-01-01

    During ornithological studies in the provinces of Jujuy, Salta, and San Juan, we recorded the Andean Swallow Orochelidon andecola at 40 localities. These are the first records in Argentina, and also represent the southernmost for the species. Some of these localities are up to 1500 m lower than the previously known elevational limit (now 800 masl), and up to 1100 km southwards. This is a relatively poorly known swallow, and we present novel natural history data. We found evidence of breeding ...

  3. The caldera of Volcan Fernandina: a remote sensing study of its structure and recent activity

    Science.gov (United States)

    Rowland, Scott K.; Munro, Duncan C.

    1992-12-01

    Air photographs taken in 1946, 1960, and 1982, together with SPOT HVR-1 images obtained in April and October of 1988, are used to characterize recent activity in and around the caldera of Fernandina Volcano, West Galapagos Islands. The eruptive and collapse events during this time span appear to be distributed in a NW-SE band across the summit and caldera. On the flanks of the volcano, subtle topographic ridges indicate that this is a long-term preferred orientation of extra-caldera activity as well (although radial and arcuate fissures are found on all sectors). The caldera is formed from the coalescence of multiple collapse features that are also distributed along a NW-SE direction, and these give the caldera its elongate and scalloped outline. The NW and SE benches consist of lavas that ponded in once-separated depressions that have been incorporated into the caldera by more recent collapse. The volume of individual eruptions within the caldera over the observed 42 years appears to be small (˜4x106 m3) in comparison to the volumes of individual flows exposed in the caldera walls (˜120 150x106 m3). Field observations (in 1989) of lavas exposed in the caldera walls and their cross-cutting relationships show that there have been at least three generations of calderas, and that at times each was completely filled. An interplay between a varying supply rate to the volcano and a regional stress regime is suggested to be the cause of long-term spatial and volumetric variations in activity. When supply is high, the caldera is filled in relative to collapse and dikes tend to propagate in all directions through the edifice. At other times (such as the present) supply is relatively low; eruptions are small, the caldera is far from being filled in, and dike propagation is influenced by an extra-volcano stress regime.

  4. Monitoring volcanic thermal activity by Robust Satellite Techniques: achievements and perspectives

    Science.gov (United States)

    Tramutoli, V.; Marchese, F.; Mazzeo, G.; Pergola, N.

    2009-12-01

    Satellite data have been increasingly used in last decades to study active volcanoes and to monitor thermal activity variation in space-time domain. Several satellite techniques and original methods have been developed and tested, devoted to hotspot detection and thermal monitoring. Among them, a multi-temporal approach, named RST (Robust Satellite Techniques), has shown high performances in detecting hotspots, with a low false positive rate under different observational and atmospheric conditions, providing also a potential toward low-level thermal anomalies which may announce incoming eruptions. As the RST scheme is intrinsically exportable on different geographic areas and satellite sensors, it has been applied and tested on a number of volcanoes and in different environmental conditions. This work presents major results and outcomes of studies carried out on Etna and Stromboli (Italy), Merapi (Java Indonesia), Asamayama (Japan), Jebel Al Tair (Yemen) by using different satellite systems and sensors (e.g. NOAA-AVHRR, EOS-MODIS, MSG-SEVIRI). Performances on hotspot detection, early warning and real-time monitoring, together with capabilities in possible thermal precursor identification, will be presented and discussed.

  5. Seismic activity and thermal regime of low temperature fumaroles at Mt. Vesuvius in 2004-2011: distinguishing among seismic, volcanic and hydrological signals

    Directory of Open Access Journals (Sweden)

    Paola Cusano

    2013-11-01

    Full Text Available Seismological, soil temperature and hydrological data from Mt. Vesuvius are collected to characterize the present-day activity of the volcanic/hydrothermal system and to detect possible unrest-related phenomena. We present patterns of seismicity and soil temperature in the crater area during the period February 2004-December 2011. The temporal distribution of number and depth of Volcano-Tectonic earthquakes and the energy release are considered. Hourly data of soil temperature have been acquired since January 2004 in different locations along the rim and within the crater. The observed changes of temperature are studied to establish a temporal-based correlation with the volcanic activity and/or with external forcing, as variations of the regional and local stress field acting on the volcano or meteorological phenomena. The comparison between seismic activity and temperature data highlights significant variations possibly related to changes in fluid circulation in the hydrothermal system of the volcano. The common continuous observations start just before a very shallow earthquake occurred in August 2005, which was preceded by a thermal anomaly. This coincidence has been interpreted as related to fluid-driven rock fracturing, as observed in other volcanoes. For the successive temporal patterns, the seismicity rate and energy release are characterized by slight variations accompanied by changes in temperature. This evidence of reactivity of the fumarole thermal field to seismic strain can be used to discriminate between tectonic and volcanic signals at Mt. Vesuvius.

  6. Emitted short wavelength infrared radiation for detection and monitoring of volcanic activity

    Science.gov (United States)

    Rothery, D. A.; Francis, P. W.; Wood, C. A.

    1988-01-01

    Thematic Mapper images from LANDSAT were used to monitor volcanoes. Achievements include: (1) the discovery of a magmatic precursor to the 16 Sept. 1986 eruption of Lascar, northern Chile, on images from Mar. and July 1985 and of continuing fumarolic activity after the eruption; (2) the detection of unreported major changes in the distribution of lava lakes on Erta'Ale, Ethiopia; and (3) the mapping of a halo of still-hot spatter surrounding a vent on Mount Erebus, Antarctica, on an image acquired 5 min after a minor eruption otherwise known only from seismic records. A spaceborne short wavelength infrared sensor for observing hot phenomena of volcanoes is proposed. A polar orbit is suggested.

  7. Imaging of volcanic activity on Jupiter's moon Io by Galileo during the Galileo Europa Mission and the Galileo Millennium Mission

    Science.gov (United States)

    Keszthelyi, L.; McEwen, A.S.; Phillips, C.B.; Milazzo, M.; Geissler, P.; Turtle, E.P.; Radebaugh, J.; Williams, D.A.; Simonelli, D.P.; Breneman, H.H.; Klaasen, K.P.; Levanas, G.; Denk, T.; Alexander, D.D.A.; Capraro, K.; Chang, S.-H.; Chen, A.C.; Clark, J.; Conner, D.L.; Culver, A.; Handley, T.H.; Jensen, D.N.; Knight, D.D.; LaVoie, S.K.; McAuley, M.; Mego, V.; Montoya, O.; Mortensen, H.B.; Noland, S.J.; Patel, R.R.; Pauro, T.M.; Stanley, C.L.; Steinwand, D.J.; Thaller, T.F.; Woncik, P.J.; Yagi, G.M.; Yoshimizu, J.R.; Alvarez, Del; Castillo, E.M.; Belton, M.J.S.; Beyer, R.; Branston, D.; Fishburn, M.B.; Mueller, B.; Ragan, R.; Samarasinha, N.; Anger, C.D.; Cunningham, C.; Little, B.; Arriola, S.; Carr, M.H.; Asphaug, E.; Moore, J.; Morrison, D.; Rages, K.; Banfield, D.; Bell, M.; Burns, J.A.; Carcich, B.; Clark, B.; Currier, N.; Dauber, I.; Gierasch, P.J.; Helfenstein, P.; Mann, M.; Othman, O.; Rossier, L.; Solomon, N.; Sullivan, R.; Thomas, P.C.; Veverka, J.; Becker, T.; Edwards, K.; Gaddis, L.; Kirk, R.; Lee, E.; Rosanova, T.; Sucharski, R.M.; Beebe, R.F.; Simon, A.; Bender, K.; Chuang, F.; Fagents, S.; Figueredo, P.; Greeley, R.; Homan, K.; Kadel, S.; Kerr, J.; Klemaszewski, J.; Lo, E.; Schwarz, W.; Williams, K.; Bierhaus, E.; Brooks, S.; Chapman, C.R.; Merline, B.; Keller, J.; Schenk, P.; Tamblyn, P.; Bouchez, A.; Dyundian, U.; Ingersoll, A.P.; Showman, A.; Spitale, J.; Stewart, S.; Vasavada, A.; Cunningham, W.F.; Johnson, T.V.; Jones, T.J.; Kaufman, J.M.; Magee, K.P.; Meredith, M.K.; Orton, G.S.; Senske, D.A.; West, A.; Winther, D.; Collins, G.; Fripp, W.J.; Head, J. W.; Pappalardo, R.; Pratt, S.; Procter, L.; Spaun, N.; Colvin, T.; Davies, M.; DeJong, E.M.; Hall, J.; Suzuki, S.; Gorjian, Z.; Giese, B.; Koehler, U.; Neukum, G.; Oberst, J.; Roatsch, T.; Tost, W.; Schuster, P.; Wagner, R.; Dieter, N.; Durda, D.; Greenberg, R.J.; Hoppa, G.; Jaeger, W.; Plassman, J.; Tufts, R.; Fanale, F.P.; Gran,

    2001-01-01

    The Solid-State Imaging (SSI) instrument provided the first high- and medium-resolution views of Io as the Galileo spacecraft closed in on the volcanic body in late 1999 and early 2000. While each volcanic center has many unique features, the majority can be placed into one of two broad categories. The "Promethean" eruptions, typified by the volcanic center Prometheus, are characterized by long-lived steady eruptions producing a compound flow field emplaced in an insulating manner over a period of years to decades. In contrast, "Pillanian" eruptions are characterized by large pyroclastic deposits and short-lived but high effusion rate eruptions from fissures feeding open-channel or open-sheet flows. Both types of eruptions commonly have ???100-km-tall, bright, SO2-rich plumes forming near the flow fronts and smaller deposits of red material that mark the vent for the silicate lavas. Copyright 2001 by the American Geophysical Union.

  8. Disturbances in groundwater chemical parameters related to seismic and volcanic activity in Kamchatka (Russia

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2004-01-01

    Full Text Available Starting from 1992 geochemical data are being collected with a mean sampling frequency of three days in the form of the pH value and of the most common ions and gases in the groundwater in one deep well located in Petropavlovsk, the capital city of Kamchatka (Russia. On 1 January 1996 a strong eruption started from the Karymsky volcano, that is located about 100km far from the well, in the north-northeastern direction. At the same time, a large earthquake (M=6.9 occurred in the Karymsky area. On 5 December 1997 a very large earthquake (M=7.7 occurred offshore, at a distance of 350km from the well and towards the same direction. The analysis of the geochemical data shows clear variations in the raw temporal trends on both cases. For the first event, a clear premonitory phase appeared; for the second one, some pre-seismic variations could be revealed but permanent modifications of the chemistry of the water subsequent to the earthquake are very clear. In both cases the feature of the geochemical variations is consistent with an afflux of new water in the aquifer connected with the well and with an escape of the Carbon dioxide gas from the ground in different directions. A schematic model able to justify such a phenomenology and the connections of the geochemical variations with the previous tectonic activities is proposed.

  9. Survey and assessment of post volcanic activities of a young caldera lake, Lake Cuicocha, Ecuador

    Directory of Open Access Journals (Sweden)

    G. Gunkel

    2009-05-01

    Full Text Available Cuicocha is a young volcano adjacent to the inactive Pleistocene Cotacachi volcano complex, located in the western cordilleras of the Ecuadorian Andes. A series of eruptions with intensive ash emission and collapse of the caldera occurred around 4500–3000 y BP. A crater 3.2 km in diameter and a maximum depth of 450 m was formed. Further eruptions of the volcano occurred 1300 y BP and formed four smaller domes within the caldera. Over the last few hundred years, a caldera lake has developed, with a maximum depth of 148 m. The lake water is characterized by sodium carbonate with elevated concentrations of manganese, calcium and chloride. Nowadays, an emission of gases, mainly CO2, and an input of warm spring water occur in Lake Cuicocha. The zone of high activity is in the western basin of the lake at a depth of 78 m, and continuous gas emissions with sediment resuspension were observed using sonar. In the hypolimnion of the lake, CO2 accumulation occurs up to 0.2% saturation, but the risk of a limnic eruption can be excluded at present. The lake possesses monomictic stratification behaviour, and during overturn an intensive gas exchange with the atmosphere occurs. Investigations concerning the sedimentation processes of the lake suggest only a thin sediment layer of up to 10–20 cm in the deeper lake basin; in the western bay, in the area of gas emissions, the lake bottom is partly depleted of sediment in the form of holes, and no lake colmation exists. Decreases in the lake water level of about 30 cm y−1 indicate a percolation of water into fractures and fissures of the volcano, triggered by a nearby earthquake in 1987.

  10. Backprojection of volcanic tremor

    Science.gov (United States)

    Haney, Matthew M.

    2014-01-01

    Backprojection has become a powerful tool for imaging the rupture process of global earthquakes. We demonstrate the ability of backprojection to illuminate and track volcanic sources as well. We apply the method to the seismic network from Okmok Volcano, Alaska, at the time of an escalation in tremor during the 2008 eruption. Although we are able to focus the wavefield close to the location of the active cone, the network array response lacks sufficient resolution to reveal kilometer-scale changes in tremor location. By deconvolving the response in successive backprojection images, we enhance resolution and find that the tremor source moved toward an intracaldera lake prior to its escalation. The increased tremor therefore resulted from magma-water interaction, in agreement with the overall phreatomagmatic character of the eruption. Imaging of eruption tremor shows that time reversal methods, such as backprojection, can provide new insights into the temporal evolution of volcanic sources.

  11. The crustal thickness and lithospheric structure of active and inactive volcanic arc terrains in Fiji and Tonga

    Science.gov (United States)

    Chen, J.; Wiens, D.; Wei, S. S.; Zha, Y.; Julià, J.; Cai, C.; Chen, Y. J.

    2015-12-01

    In order to investigate the crustal thickness and lithospheric structure beneath active and inactive volcanic arcs in Fiji and Tonga, we analyzed receiver functions from teleseismic P waves as well as Rayleigh waves from teleseismic earthquakes and ambient noise. The data were recorded by stations from three previous temporary seismic arrays deployed on the islands during 1993-1995, 2001-2002, and 2009-2010. Receiver functions were calculated with an iterative deconvolution in the time domain. We used an H-k stacking method to get preliminary Moho depth estimates under the island arcs, after assuming constant seismic average crustal P velocity. We also determined the shear wave velocity structure beneath each station from a 1-D combined inversion of receiver functions and Rayleigh wave phase velocity dispersion curves from ambient noise cross correlation at 8s - 20s and teleseismic surface waves at 20s-90s. The joint inversion models reveal that the Moho beneath the main islands of the Fiji plateau is 26-31 km deep, whereas the crust under the outer islands - including the Lau Ridge - is generally thinner, with Moho depths of 21-23.5 km. The thinnest crust (16 km) is found beneath Moala Island located between the Fiji Platform and the Lau Ridge. Crustal thickness beneath several Tonga islands is about 18-20 km. A relatively high velocity lithosphere (Vs of 4.4 - 4.5 km/s) extends to only about 60 km depth beneath the outer Fiji Islands and Lau Ridge, but to depths of 90 km underneath the main islands of the Fiji Plateau. The much thicker crust and lithosphere of the Fiji plateau relative to the Lau Ridge and Tonga Arc reflects its much longer geological history of arc crust building, going back to the early Miocene.

  12. The fate of arsenic in a river acidified by volcanic activity and an acid thermal water and sedimentation mechanism.

    Science.gov (United States)

    Ogawa, Yasumasa; Yamada, Ryoichi; Shinoda, Kozo; Inoue, Chihiro; Tsuchiya, Noriyoshi

    2014-01-01

    The Shozu-gawa river, located in the Aomori Prefecture, northern Japan, is affected by volcanic activities and acid thermal waters. The river is unique because both solid arsenic (As; as orpiment, As2S3) and dissolved As are supplied to the river from the uppermost caldera lake (Usori-ko Lake) and thermal ponds. The watershed is an excellent site for investigating the fate of different As species in a fluvial system. Upstream sediments near the caldera lake and geothermal ponds are highly contaminated by orpiment. This solid phase is transported as far as the mouth of the river. On the other hand, dissolved As is removed from the river system by hydrous ferric oxides (HFOs); however, HFO formation and removal of dissolved As do not occur in the uppermost area of the watershed, resulting in further downstream transport of dissolved As. Consequently, upstream river sediments are enriched in orpiment, whereas As(v), which is associated with HFOs in river sediments, increases downstream. Furthermore, orpiment particles are larger, and possibly heavier, than those of HFO with sorbed As. Fractionation between different chemical states of As during transport in the Shozu-gawa river is facilitated not only by chemical processes (i.e., sorption of dissolved As by HFOs), but also by physical factors (i.e., gravity). In contrast to acid mine drainage (AMD), in some areas of the Shozu-gawa river, both solid forms of As (as sulfide minerals) and dissolved As are introduced into the aquatic system. Considering that the stabilities of sulfide minerals are rather different from those of oxides and hydroxides, river sediments contacted with thermal waters possibly act as sources of As under both aerobic and anaerobic conditions.

  13. Adakite-like volcanism of Ecuador: lower crust magmatic evolution and recycling

    Science.gov (United States)

    Chiaradia, Massimo; Müntener, Othmar; Beate, Bernardo; Fontignie, Denis

    2009-11-01

    In the Northern Andes of Ecuador, a broad Quaternary volcanic arc with significant across-arc geochemical changes sits upon continental crust consisting of accreted oceanic and continental terranes. Quaternary volcanic centers occur, from west to east, along the Western Cordillera (frontal arc), in the Inter-Andean Depression and along the Eastern Cordillera (main arc), and in the Sub-Andean Zone (back-arc). The adakite-like signatures of the frontal and main arc volcanoes have been interpreted either as the result of slab melting plus subsequent slab melt-mantle interactions or of lower crustal melting, fractional crystallization, and assimilation processes. In this paper, we present petrographic, geochemical, and isotopic (Sr, Nd, Pb) data on dominantly andesitic to dacitic volcanic rocks as well as crustal xenolith and cumulate samples from five volcanic centers (Pululagua, Pichincha, Ilalo, Chacana, Sumaco) forming a NW-SE transect at about 0° latitude and encompassing the frontal (Pululagua, Pichincha), main (Ilalo, Chacana), and back-arc (Sumaco) chains. All rocks display typical subduction-related geochemical signatures, such as Nb and Ta negative anomalies and LILE enrichment. They show a relative depletion of fluid-mobile elements and a general increase in incompatible elements from the front to the back-arc suggesting derivation from progressively lower degrees of partial melting of the mantle wedge induced by decreasing amounts of fluids released from the slab. We observe widespread petrographic evidence of interaction of primary melts with mafic xenoliths as well as with clinopyroxene- and/or amphibole-bearing cumulates and of magma mixing at all frontal and main arc volcanic centers. Within each volcanic center, rocks display correlations between evolution indices and radiogenic isotopes, although absolute variations of radiogenic isotopes are small and their values are overall rather primitive (e.g., ɛNd = +1.5 to +6, 87Sr/86Sr = 0

  14. The subduction erosion and mantle source region contamination model of Andean arc magmatism: Isotopic evidence from igneous rocks of central Chile

    International Nuclear Information System (INIS)

    Stern, Charles R

    2001-01-01

    Continental crust may be incorporated in mantle-derived Andean magmas as these magmas rise through the crust (Hildreth and Moorbath, 1988), or alternatively, crust may be tectonically transported into the mantle by subduction of trench sediments and subduction erosion of the continental margin, and then added into the mantle source region of Andean magmas (Stern, 1991). Since the mantle has relatively low Sr, Nd, and Pb concentrations compared to continental crust, differences in the isotopic compositions of magmas erupted in different region of the Andes may be produced by relatively small differences in the amount of subducted crust added to the mantle source region of these magmas. By comparison, significantly larger amounts of crust must be assimilated by mantle-derived magmas to produce isotopic differences of similar magnitude. Therefore, constraining the process by which continental crust is incorporated in Andean magmas has important implications for understanding the chemical cycling that takes place in the Andean subduction-related magma factory. Isotopic data suggest the incorporation of a greater proportion of crust in Andean magmas erupted at the northern portion of the Southern Volcanic Zone of central Chile compared to those erupted in the southern portion of the Southern Volcanic Zone of south central Chile (SSVZ) (Stern et al., 1984; Futa and Stern, 1988; Hildreth and Moorbath, 1988). The NSVZ occurs just south of the current locus of the subduction of the Juan Fernandez Ridge. The southward migration of the locus of subduction of this ridge has resulted in decreasing subduction angle below the NSVZ, the eastward migration of the volcanic front of the Andean arc, and an increase in the crustal thickness below the arc. These factors together have caused changes, since the middle Miocene, in the isotopic composition of Andean igneous rocks of central Chile. The data indicate a close chronologic relation between the southward migrations of the locus

  15. Seismically active column and volcanic plumbing system beneath the island arc of the Izu-Bonin subduction zone

    Czech Academy of Sciences Publication Activity Database

    Špičák, Aleš; Vaněk, Jiří; Hanuš, Václav

    2009-01-01

    Roč. 179, č. 3 (2009), s. 1301-1312 ISSN 0956-540X Institutional research plan: CEZ:AV0Z30120515 Keywords : seismicity and tectonics * volcano seismology * subduction zone processes * volcanic arc processes * magma migration and fragmentation * Pacific Ocean Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.435, year: 2009

  16. Reconstruction of eroded monogenic Strombolian cones of Miocene age: A case study on character of volcanic activity of the Jičín Volcanic Field (NE Bohemia) and subsequent erosional rates estimation

    Czech Academy of Sciences Publication Activity Database

    Rapprich, V.; Cajz, Vladimír; Košťák, M.; Pécskay, Z.; Řídkošil, T.; Raška, P.; Radoň, M.

    2007-01-01

    Roč. 52, 3-4 (2007), s. 169-180 ISSN 0449-2560 R&D Projects: GA AV ČR IAA300130612 Institutional research plan: CEZ:AV0Z30130516 Keywords : cinder cone * Strombolian eruption * volcanic facies * erosion rate * Jičín Volcanic Field * Bohemian Paradise GeoPark Subject RIV: DB - Geology ; Mineralogy

  17. Marking behavior of Andean bears in an Ecuadorian cloud forest

    NARCIS (Netherlands)

    Filipczyková, Eva; Heitkonig, Ignas; Castellanos, Armando; Hantson, Wouter; Steyaert, Sam M.J.G.

    2017-01-01

    Very little is known about marking behavior of the endangered Andean bear (Tremarctos ornatus). Here, we present a first detailed description of Andean bear marking behavior obtained using camera traps. From November 2012 to April 2013, we inspected 16 bear trails in the Napo province of eastern

  18. The Under-side of the Andes: Using Receiver Functions to Map the North Central Andean Subsurface

    Science.gov (United States)

    Ryan, J. C.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2012-12-01

    The Central Andean Uplift and Geodynamics of High Topography (CAUGHT) project is an interdisciplinary project to investigate connections between lithospheric removal, crustal shortening and surface uplift in the northern Bolivia and southern Peru region of the South American Andean orogen. The central Andes are defined by six major tectonomorphic provinces; the forearc, the volcanically active Western Cordillera (WC, ~6 km elevation), the internally drained Altiplano (~4 km elevation), an inactive fold and thrust belt in the Eastern Cordillera (EC, ~6 km elevation), a lower elevation active fold and thrust belt in the Subandean (SA) zone and the Beni, a foreland basin. Forty seismic stations installed for the CAUGHT project were deployed between 13° and 18° S latitude, covering the transition zone where the Altiplano region pinches out in southern Peru, in an effort to better constrain the changing character of the crust and mantle lithosphere. Geologic studies across the northern Bolivian portion of the eastern Andean margin (15-17° S) have documented a total of 275 km of upper crustal shortening (McQuarrie et al, Tectonics, v27, 2008), which may be associated with crustal thickening and/or the removal of lithospheric material as a thickened lithosphere root becomes unstable. For this receiver function (converted wave) study, we have little coverage in the forearc and foreland, ~75 km spacing in most of the array, and a relatively dense ~20 km spaced profile along the Charaña-La Paz-Yucumo transect, the eastern portion of which is nearly coincident with the balanced cross-section of McQuarrie et al. (2008). Using the first year of available data, more than 1200 receiver functions have been calculated using an iterative deconvolution method, and stacked using the common conversion point (CCP) method, along profiles parallel to and nearly coincident to those used for the geologic shortening estimates. We identified arrivals for the Moho and generated a 3D map of

  19. 77 FR 28620 - Andean Trade Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication

    Science.gov (United States)

    2012-05-15

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 332-352] Andean Trade Preference Act: Impact on the U.S. Economy and on Andean Drug Crop Eradication AGENCY: United States International Trade... to report biennially to the Congress by September 30 of each reporting year on the economic impact of...

  20. Unity and Difference in Andean Songs

    Directory of Open Access Journals (Sweden)

    Charles Maurice Pigott

    2013-03-01

    Full Text Available This essay explores the concepts of “unity” and “difference” in Andean songs. The verses pertain to the Masha ritual enacted annually in Mangas, central Peru, and combine Quechua (the indigenous language with Spanish. Through detailed exegesis of the texts, this essay argues that, far from being irreconcilable, “unity” and “difference” are best understood as mutually informing since the recognition of difference opens up the parameters of potential exchange. This optic is informed by a worldview that emphasizes “relation” over “entities.”

  1. Enrichments of the mantle sources beneath the Southern Volcanic Zone (Andes) by fluids and melts derived from abraded upper continental crust

    DEFF Research Database (Denmark)

    Holm, Paul Martin; Søager, Nina; Dyhr, Charlotte Thorup

    2014-01-01

    Mafic basaltic-andesitic volcanic rocks from the Andean Southern Volcanic Zone (SVZ) exhibit a northward increase in crustal components in primitive arc magmas from the Central through the Transitional and Northern SVZ segments. New elemental and Sr–Nd-high-precision Pb isotope data from the Quat......Mafic basaltic-andesitic volcanic rocks from the Andean Southern Volcanic Zone (SVZ) exhibit a northward increase in crustal components in primitive arc magmas from the Central through the Transitional and Northern SVZ segments. New elemental and Sr–Nd-high-precision Pb isotope data from...... mantle by means of subduction erosion in response to the northward increasingly strong coupling of the converging plates. Both types of enrichment had the same Pb isotope composition in the TSVZ with no significant component derived from the subducting oceanic crust. Pb–Sr–Nd isotopes indicate a major...

  2. The Timber Mountain magmato-thermal event: An intense widespread culmination of magmatic and hydrothermal activity at the southwestern Nevada volcanic field

    International Nuclear Information System (INIS)

    Jackson, M.R. Jr.

    1988-05-01

    Eruption of the Rainier Mesa and Ammonia Tanks Members Timber Mountain Tuff at about 11.5 and 11.3 Ma, respectively, resulted in formation of the timber Mountain (TM) caldera; new K-Ar ages show that volcanism within and around the TM caldera continued for about 1 m.y. after collapse. Some TM age magmatic activity took place west and southeast of the TM caldera in the Beatty -- Bullfrog Hills and Shoshone Mountain areas, suggesting that volcanic activity at the TM caldera was an intense expression of an areally extensive magmatic system active from about 11.5 to 10Ma. Epithermal Au-Ag, Hg and fluorite mineralization and hydrothermal alteration are found in both within and surrounding the Timber Mountain -- Oasis Valley caldera complex. New K-Ar ages date this hydrothermal activity between about 13 and 10 Ma, largely between about 11.5 and 10 Ma, suggesting a genetic relation of hydrothermal activity to the TM magmatic system

  3. The Timber Mountain magmato-thermal event: An intense widespread culmination of magmatic and hydrothermal activity at the southwestern Nevada volcanic field

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Jr., Mac Roy [Univ. of Nevada, Reno, NV (United States)

    1988-05-01

    Eruption of the Rainier Mesa and Ammonia Tanks Members Timber Mountain Tuff at about 11.5 and 11.3 Ma, respectively, resulted in formation of the timber Mountain (TM) caldera; new K-Ar ages show that volcanism within and around the TM caldera continued for about 1 m.y. after collapse. Some TM age magmatic activity took place west and southeast of the TM caldera in the Beatty -- Bullfrog Hills and Shoshone Mountain areas, suggesting that volcanic activity at the TM caldera was an intense expression of an areally extensive magmatic system active from about 11.5 to 10Ma. Epithermal Au-Ag, Hg and fluorite mineralization and hydrothermal alteration are found in both within and surrounding the Timber Mountain -- Oasis Valley caldera complex. New K-Ar ages date this hydrothermal activity between about 13 and 10 Ma, largely between about 11.5 and 10 Ma, suggesting a genetic relation of hydrothermal activity to the TM magmatic system.

  4. Change detection and characterization of volcanic activity using ground based low-light and near infrared cameras to monitor incandescence and thermal signatures

    Science.gov (United States)

    Harrild, Martin; Webley, Peter; Dehn, Jonathan

    2015-04-01

    Knowledge and understanding of precursory events and thermal signatures are vital for monitoring volcanogenic processes, as activity can often range from low level lava effusion to large explosive eruptions, easily capable of ejecting ash up to aircraft cruise altitudes. Using ground based remote sensing techniques to monitor and detect this activity is essential, but often the required equipment and maintenance is expensive. Our investigation explores the use of low-light cameras to image volcanic activity in the visible to near infrared (NIR) portion of the electromagnetic spectrum. These cameras are ideal for monitoring as they are cheap, consume little power, are easily replaced and can provide near real-time data. We focus here on the early detection of volcanic activity, using automated scripts, that capture streaming online webcam imagery and evaluate image pixel brightness values to determine relative changes and flag increases in activity. The script is written in Python, an open source programming language, to reduce the overall cost to potential consumers and increase the application of these tools across the volcanological community. In addition, by performing laboratory tests to determine the spectral response of these cameras, a direct comparison of collocated low-light and thermal infrared cameras has allowed approximate eruption temperatures and effusion rates to be determined from pixel brightness. The results of a field campaign in June, 2013 to Stromboli volcano, Italy, are also presented here. Future field campaigns to Latin America will include collaborations with INSIVUMEH in Guatemala, to apply our techniques to Fuego and Santiaguito volcanoes.

  5. Multidisciplinary exploratory study of a geothermal resource in the active volcanic arc of Basse-Terre (Guadeloupe, Lesser Antilles)

    Science.gov (United States)

    Navelot, Vivien; Favier, Alexiane; Géraud, Yves; Diraison, Marc; Corsini, Michel; Verati, Chrystèle; Lardeaux, Jean-Marc; Mercier de Lépinay, Jeanne; Munschy, Marc

    2017-04-01

    The GEOTREF project (high enthalpy geothermal energy in fractured reservoirs), supported by the French government program, "Investissements d'avenir" develops a sustainable geothermal resource in the Vieux Habitants area, 8-km south of the currently exploited Bouillante geothermal field. The Basse Terre Island is a recent volcanic arc (meta-andesite. This metamorphism forms cleavage plans thanks to a pressure-solution mechanism. Mineralogical transformations associated with these cleavage planes have an impact on petrophysical properties. The solid phase density and porosity decrease. An anisotropy of permeability develops due to cleavage plans. Thermodynamics modelling based on the rock chemical composition and petrography observations emphasizes a steady-state mineral assemblage between 1.5 - 2 kbar and 280 - 320˚ C. This is consistent with an in situ measured volcanic arc conductive geothermal gradient of 70 ˚ C/km.

  6. Seismic reflection data processing in active volcanic areas: an application to Campi Flegrei and Somma Vesuvius offshore (Southern Italy

    Directory of Open Access Journals (Sweden)

    A. Rapolla

    2002-06-01

    Full Text Available The Campanian volcanism develops near the sea. Therefore, the geophysical study of the marine environment is a key to a better understanding of the tectonic evolution and the origin of volcanism in the area. An abundance of high quality seismic data in the marine sector, where little direct information is available, is critical to the study of Campanian volcanism. This paper concerns the reprocessing of a seismic reflection dataset acquired in Naples Bay and processed during 1973. Even though the overall data quality was high for that time, of course their acquisition technological limits have been overcome by the new processing. Our reprocessing aimed at: 1 reduction of random noise in the data; 2 removal of unwanted coherent events; 3 reduction of spatial aliasing by means of trace interpolation on Commod Shot Point (CSP gathering; 4 improvement of resolution of the seismic wavelet with spiking deconvolution algorithms and finally 5 reposition of reflectors in their correct locations in the space-TWT domain by means of dip moveout and post-stack time migration. A comparison between the new and old data shows that the new sections are characterized by a much higher S/N ratio. Diffraction hyperbole has been collapsed. Reverberations, ghosts and multiples have been removed or greatly attenuated, especially between the reflectors of interest, allowing us to follow them with more detail and with greater continuity. Furthermore, data resolution has been boosted by the reprocessing, allowing the interpreter to evaluate reflector position and continuity in greater detail. The reinterpretation phase of such lines, that is already in an advanced stage, will therefore allow us to gain new insights into the structural setting of the bay, with the aim of exploring the connection between tectonics and volcanism.

  7. Seismic activity around and under Krakatau volcano, Sunda Arc: constraints to the source region of island arc volcanics

    Czech Academy of Sciences Publication Activity Database

    Špičák, Aleš; Hanuš, Václav; Vaněk, Jiří

    2002-01-01

    Roč. 46, č. 3 (2002), s. 545-565 ISSN 0039-3169 R&D Projects: GA ČR GA205/97/0898; GA AV ČR IAA3012002 Institutional research plan: CEZ:AV0Z3012916 Keywords : Krakatau * Sunda Strait seismicity * island arc volcanism * subduction * Wadati-Benioff zone Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.571, year: 2002

  8. Subaqueous volcanism in the Etnean area: evidence for hydromagmatic activity and regional uplift inferred from the Castle Rock of Acicastello

    Science.gov (United States)

    Corsaro, R. A.; Cristofolini, R.

    2000-01-01

    The subalkaline rocks outcropping at the Acicastello Castle Rock, Catania, Sicily, and on its abrasion platforms, are related to the oldest Etnean volcanism (500-300 ka; [Gillot, P.Y., Kieffer, G., Romano, R., 1994. The evolution of Mount Etna in the light of potassium-argon dating. Acta Vulcanol. 5, 81-87.]). Here, submarine lavas with pillows closely packed onto each other are associated with heterogeneous and poorly sorted volcaniclastic breccia levels with sub-vertical sharp boundaries. The present-day attitude was previously interpreted as due to a local tilt [Di Re, M., 1963. Hyaloclastites and pillow-lavas of Acicastello (Mt. Etna). Bull. Volcanol. 25, 281-284.; Kieffer, G., 1985. Evolution structurale et dynamique d'un grand volcan polygenique: stades d'edification et activitè actuelle de l'Etna (Sicile). Clermont Ferrand IIDoctorat Etat Tesi, Clermont Ferrand II.], or to the seaward sliding of the entire eastern Etnean flank [Borgia, A., Ferrari, L., Pasquarè, G., 1992. Importance of gravitational spreading in the tectonic and volcanic evolution of Mount Etna. Nature 357, 231-235.], on the assumption of originally horizontal boundaries. On the contrary, our observations do not match the hypothesis of a significantly tilted succession and lead us to conclude that, apart from the strong regional uplift, the present Castle Rock exposure did not suffer any substantial change of its attitude.

  9. Statistical eruption forecast for the Chilean Southern Volcanic Zone: typical probabilities of volcanic eruptions as baseline for possibly enhanced activity following the large 2010 Concepción earthquake

    Directory of Open Access Journals (Sweden)

    Y. Dzierma

    2010-10-01

    Full Text Available A probabilistic eruption forecast is provided for ten volcanoes of the Chilean Southern Volcanic Zone (SVZ. Since 70% of the Chilean population lives in this area, the estimation of future eruption likelihood is an important part of hazard assessment. After investigating the completeness and stationarity of the historical eruption time series, the exponential, Weibull, and log-logistic distribution functions are fit to the repose time distributions for the individual volcanoes and the models are evaluated. This procedure has been implemented in two different ways to methodologically compare details in the fitting process. With regard to the probability of at least one VEI ≥ 2 eruption in the next decade, Llaima, Villarrica and Nevados de Chillán are most likely to erupt, while Osorno shows the lowest eruption probability among the volcanoes analysed. In addition to giving a compilation of the statistical eruption forecasts along the historically most active volcanoes of the SVZ, this paper aims to give "typical" eruption probabilities, which may in the future permit to distinguish possibly enhanced activity in the aftermath of the large 2010 Concepción earthquake.

  10. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.; Delworth, Thomas L.; Ramaswamy, V.; Stouffer, Ronald J.; Wittenberg, Andrew; Zeng, Fanrong

    2009-01-01

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean

  11. Global scale concentrations of volcanic activity on Venus: A summary of three 23rd Lunar and Planetary Science Conference abstracts. 1: Venus volcanism: Global distribution and classification from Magellan data. 2: A major global-scale concentration of volcanic activity in the Beta-Atla-Themis region of Venus. 3: Two global concentrations of volcanism on Venus: Geologic associations and implications for global pattern of upwelling and downwelling

    Science.gov (United States)

    Crumpler, L. S.; Aubele, Jayne C.; Head, James W.; Guest, J.; Saunders, R. S.

    1992-01-01

    As part of the analysis of data from the Magellan Mission, we have compiled a global survey of the location, dimensions, and subsidiary notes of all identified volcanic features on Venus. More than 90 percent of the surface area was examined and the final catalog comprehensively identifies 1548 individual volcanic features larger than approximately 20 km in diameter. Volcanic features included are large volcanoes, intermediate volcanoes, fields of small shield volcanoes, calderas, large lava channels, and lava floods as well as unusual features first noted on Venus such as coronae, arachnoids, and novae.

  12. Volcanic risk; Risque volcanique

    Energy Technology Data Exchange (ETDEWEB)

    Rancon, J.P.; Baubron, J.C.

    1995-12-31

    This project follows the previous multi-disciplinary studies carried out by the French Bureau de Recherches Geologiques et Minieres (BRGM) on the two active volcanoes of the French lesser Antilles: Mt Pelee (Martinique) and Soufriere (Guadeloupe) for which geological maps and volcanic risk studies have been achieved. The research program comprises 5 parts: the study of pyroclastic deposits from recent eruptions of the two volcanoes for a better characterization of their eruptive phenomenology and a better definition of crisis scenarios; the study of deposits and structures of active volcanoes from Central America and the study of eruptive dynamics of andesite volcanoes for a transposition to Antilles` volcanoes; the starting of a methodological multi-disciplinary research (volcanology, geography, sociology...) on the volcanic risk analysis and on the management of a future crisis; and finally, the development of geochemical survey techniques (radon, CO{sub 2}, H{sub 2}O) on active volcanoes of Costa-Rica and Europe (Fournaise, Furnas, Etna) and their application to the Soufriere. (J.S.). 9 refs., 3 figs.

  13. Classifcation of volcanic structure in mesozoic era in the Fuzhou-Shaoxing area

    International Nuclear Information System (INIS)

    Zhang Fengqi.

    1989-01-01

    The volcanic structure in the Fuzhou-Shaoxing area can be classified into IV grades: the grade I be the zone of volcanic activity; the grade II be the second zone of volcanic activity; the grade III be the positive, negative volcanic structure; the grade IV be volcanic conduit, volcanic crater, concealed eruption breccia pipe. Based on the geological situation in this area, the different types of volcanic structure are also dealt with. In the mean time, both the embossed type in the depression area and the depressed type in the embossed area in the volcanic basin are pointed out. It is of great advantage to Uranium mineralization

  14. Pattern of genetic differentiation of an incipient speciation process: The case of the high Andean killifish Orestias

    Science.gov (United States)

    Guerrero-Jiménez, Claudia Jimena; Peña, Fabiola; Morales, Pamela; Méndez, Marco; Sallaberry, Michel; Vila, Irma; Poulin, Elie

    2017-01-01

    During the Pleistocene and Holocene, the southwest Andean Altiplano (17°-22°S) was affected by repeated fluctuations in water levels, high volcanic activity and major tectonic movements. In the early Holocene the humid Tauca phase shifted to the arid conditions that have lasted until the present, producing endorheic rivers, lakes, lagoons and wetlands. The endemic fish Orestias (Cyprinodontidae) represents a good model to observe the genetic differentiation that characterizes an incipient speciation process in allopatry since the morphospecies described inhabit a restricted geographic area, with present habitat fragmentation. The genetic diversity and population structure of four endemic morphospecies of Orestias (Cyprinodontidae) found in the Lauca National Park (LNP) analyzed with mitochondrial markers (Control Region) and eight microsatellites, revealed the existence of genetic groups that matches the fragmentation of these systems. High values of genetic and phylogeographic differentiation indices were observed between Chungará Lake and Piacota lagoon. The group composed of the Lauca River, Copapujo and Chuviri wetlands sampling sites showed a clear signal of expansion, with a star-like haplotype network. Levels of genetic differentiation were lower than in Chungará and Piacota, suggesting that these localities would have differentiated after the bottlenecks linked to the collapse of Parinacota volcano. The Parinacota sample showed a population signal that differed from the other localities revealing greater genetic diversity and a disperse network, presenting haplotypes shared with other LNP localities. A mixing pattern of the different genetic groups was evident using the microsatellite markers. The chronology of the vicariance events in LNP may indicate that the partition process of the Orestias populations was gradual. Considering this, and in view of the genetic results, we may conclude that the morphospecies from LNP are populations in ongoing

  15. Magmatic Activity Beneath the Quiescent Three Sisters Volcanic Center, Central Oregon Cascade Range, USA, Inferred from Satellite InSAR

    Science.gov (United States)

    Wicks, C. W.; Dzurisin, D.; Ingebritsen, S.; Thatcher, W.; Lu, Z.; Iverson, J.

    2001-12-01

    Images from satellite interferometric synthetic aperture radar (InSAR) reveal uplift of a broad ~10 km by 20 km area in the Three Sisters volcanic center of the central Oregon Cascade Range, ~130 km south of Mt. St. Helens. The uplift is centered ~5 km west of South Sister volcano, the youngest stratovolcano in the volcanic center. The center has been volcanically inactive since the last eruption ~1500 years ago. Multiple European Space Agency ERS-1 and 2 satellite images from 1992 through 2000, used in this study, were selected based on orbital separation and time of year. Summer and early autumn scenes were necessary to avoid decorrelation from snow cover. Interferograms generated from these images indicate that most if not all of ~100 mm of observed uplift occurred between September 1998 and October 2000. We interpret the uplift as inflation caused by an apparently ongoing episode of magma intrusion at a depth of ~6.5 km. Geochemical (water chemistry) anomalies, first noted ~1990, coincide with the area of uplift and suggest the existence of a magma reservoir prior to the uplift. High chloride and sulfate concentrations, and a positive correlation between chloride concentration and spring temperature were found within the uplift area, with larger SO4/Cl ratios in springs at higher elevations. These findings are indicative of a high-temperature hydrothermal system driven by magma intrusions. The current inflation episode observed with InSAR may lead to an eruption, but the more persistent geochemical evidence suggests that the episode is likely the latest in a series of hitherto undetected magma intrusions. We do not yet know if the inflation has abated, is continuing, or has accelerated since October 2000--we only know that the highest rate of uplift occurred in the last year for which ERS-2 data was available (1999- 2000). In May of 2001, a continuous GPS receiver and seismometer were installed by the USGS within the Three Sisters Wilderness to monitor the

  16. Relationship between Diffuse CO2 Degassing and Volcanic Activity. Case Study of the Poás, Irazú, and Turrialba Volcanoes, Costa Rica

    Directory of Open Access Journals (Sweden)

    Matthieu Epiard

    2017-10-01

    Full Text Available Active volcanoes exhibit diffuse gas emanations through the ground, the most abundant species of which is CO2. However, the relationship between diffuse degassing and volcanic activity is not often clear and some volcanoes may have low diffuse degassing levels despite having strong volcanic activity. The main goals of this study are to quantify diffuse CO2 degassing and determine whether patterns exist in relation to volcanic activity through the study of Turrialba, Poás, and Irazú, three active volcanoes in Costa Rica which are at different stages of activity. Structural controls of spatial distribution of diffuse degassing were also investigated. Measurement campaigns were conducted using the accumulation chamber method coupled with 10 cm depth ground temperature sampling with the aim of estimating the total diffuse CO2 degassing budget. The total amount of CO2 emitted diffusely by each volcano is ~113 ± 46 t/d over ~0.705 km2 for Turrialba, 0.9 ± 0.5 t/d for Poás over ~0.734 km2, 3.8 ± 0.9 t/d over ~0.049 km2 for Irazú's main crater, and 15 ± 12 t/d over 0.0059 km2 for Irazú's north flank. Turrialba and Poás volcano diffuse degassing budget represent about 10% of the whole gas output. Both volcanoes were in a transitional stage and the opening of new conduits may cause a loss in diffuse degassing and an increase of active degassing. Numerous diffuse degassing structures were also identified. At Turrialba, one of which was closely associated with the collapse of a crater wall in 2014 during the initiation of a new period of heightened eruptive activity. Similar structures were also observed on the outer slopes of the west crater, suggesting strong alteration and perhaps destabilization of the upper outer cone. Irazú's north flank is highly permeable and has experienced intense hydrothermal alteration.

  17. Rate of volcanism on Venus

    International Nuclear Information System (INIS)

    Fegley, B. Jr.; Prinn, R.G.

    1988-07-01

    The maintenance of the global H 2 SO 4 clouds on Venus requires volcanism to replenish the atmospheric SO 2 which is continually being removed from the atmosphere by reaction with calcium minerals on the surface of Venus. The first laboratory measurements of the rate of one such reaction, between SO 2 and calcite (CaCO 3 ) to form anhydrite (CaSO 4 ), are reported. If the rate of this reaction is representative of the SO 2 reaction rate at the Venus surface, then we estimate that all SO 2 in the Venus atmosphere (and thus the H 2 SO 4 clouds) will be removed in 1.9 million years unless the lost SO 2 is replenished by volcanism. The required rate of volcanism ranges from about 0.4 to about 11 cu km of magma erupted per year, depending on the assumed sulfur content of the erupted material. If this material has the same composition as the Venus surface at the Venera 13, 14 and Vega 2 landing sites, then the required rate of volcanism is about 1 cu km per year. This independent geochemically estimated rate can be used to determine if either (or neither) of the two discordant (2 cu km/year vs. 200 to 300 cu km/year) geophysically estimated rates is correct. The geochemically estimated rate also suggests that Venus is less volcanically active than the Earth

  18. The Lathrop Wells volcanic center

    International Nuclear Information System (INIS)

    Crowe, B.; Morley, R.

    1992-01-01

    The Lathrop Wells volcanic center is located 20 km south of the potential Yucca Mountain site, at the south end of the Yucca Mountain range. This paper discusses a detailed Study Plan which was prepared describing planned geochronology and field studies to assess the chronology of the Lathrop Wells volcanic center and other Quaternary volcanic centers in the region. A paper was published discussing the geomorphic and soil evidence for a late Pleistocene or Holoceno age for the main cone of the center. The purpose of this paper was to expose the ideas concerning the age of the Lathrop Wells center to scientific scrutiny. Additionally, field evidence was described suggesting the Lathrop Wells center may have formed from multiple eruptive events with significant intervals of no activity between events. This interpretation breaks with established convention in the volcanological literature that small volume basalt centers are monogenetic

  19. Evolution of ice-dammed proglacial lakes in Última Esperanza, Chile: implications from the late-glacial R1 eruption of Reclús volcano, Andean Austral Volcanic Zone Evolución de lagos proglaciales embalsados por hielo en Última Esperanza, Chile: Implicancias de la explosión volcánica tardiglacial R1 del volcán Reclús, Zona Volcánica Austral Andina

    Directory of Open Access Journals (Sweden)

    Charles R Stern

    2011-01-01

    Full Text Available Newly described outerops, excavations and sediment cores from the region of Última Esperanza, Magallanes, contain tephra derived from the large late-glacial explosive Rl eruption of the Reclús volcano in the Andean Austral Volcanic Zone. New radiocarbon dates associated to these deposits refine previous estimates of the age, to 14.9 cal kyrs BP (12,670±240 14C yrs BP, and volume, to >5 km³, of this tephra. The geographic and stratigraphic distribution of Rl also place constraints on the evolution of the ice-dammed proglacial lake that existed east of the cordillera in this area between the termination of the Last Glacial Maximum (LGM and the Holocene. This proglacial lake generated wave-cut terraces, and also caves, such as the Cueva de Milodón, along the highest prominent terrace. The current elevation of these terraces depends on the total amount of post-glacial isostatic rebound, which is unknown. Due to differential rebound, the highest prominent lake terraces decrease in height from west-to-east, from -170 m a.s.l. on Península Antonio Varas west of Seno Ultima Esperanza, to-150 m a.s.l. aroundLago Sofía, anddownto-125 m a.s.l. along their easternmost margin. The presence of thick deposits of Rl tephra in some of the caves around Lago Sofía implies that the proglacial lake had already dropped below its highest level prior to the time of this eruption, and, in fact, even earlier, prior to 16.1 cal kyrs BP (13,560±180 14C yrs BP, when land mammals first oceupied these caves. The depositional environment of Rl in a core from Dumestre bog suggests that the lake level was in fact 70 m a.s.l. until 12.8 cal kyrs BP (10,695±40 14C yrs BP. However, a 14.2 cal kyrs BP (12,125±85 14C yrs BF Mylodon pelvis from a nearby site, located at only -7 m a.s.l., suggests that the lake could have emptied, for at least a brief period, to this low level at this time. This latter datum, combined with the lack of any prominent terraces between the

  20. Pore Fluid Evolution Influenced by Volcanic Activities and Related Diagenetic Processes in a Rift Basin: Evidence from the Paleogene Medium-Deep Reservoirs of Huanghekou Sag, Bohai Bay Basin, China

    Directory of Open Access Journals (Sweden)

    Zhongheng Sun

    2017-01-01

    Full Text Available Volcanic activities exert a significant influence on pore fluid property and related diagenetic processes that substantially controlled reservoirs quality. Analysis of Paleogene medium-deep sandstones on the Huanghekou Sag provides insight into relating the diagenetic processes to pore fluid property evolution influenced by volcanic activities. Three distinct types of pore fluids were identified on the basis of an integrated and systematic analysis including core and thin section observation, XRD, SEM, CL, and trace element. Alkaline aqueous medium environment occurred in E2s1+2 where volcanic activities have insignificant influence on pore fluids, evidenced by typical alkaline diagenetic events such as K-feldspar albitization, quartz dissolution, feldspar dissolution, and carbonate cementation. During the deposition of E3d3, influx of terrestrial freshwater and alteration of ferromagnesian-rich pore water result in the formation of mixing aqueous medium environment through volcanic eruption dormancy causing zeolite dissolution, clay mineral transformation, and K-feldspar albitization. Ferromagnesian-rich aqueous medium environment developed resulting from the intensive hydrolysis of the unstable ferromagnesian minerals formed due to intense volcanic activities during E3d1+2 and corresponding predominant diagenetic processes were characterized by the precipitation and dissolution of low-silica zeolites. Therefore, the differential properties of pore fluids caused various diagenetic processes controlling reservoir quality.

  1. Recent and Hazardous Volcanic Activity Along the NW Rift Zone of Piton De La Fournaise Volcano, La Réunion Island

    Science.gov (United States)

    Walther, G.; Frese, I.; Di Muro, A.; Kueppers, U.; Michon, L.; Metrich, N.

    2014-12-01

    Shield volcanoes are a common feature of basaltic volcanism. Their volcanic activity is often confined to a summit crater area and rift systems, both characterized by constructive (scoria and cinder cones; lava flows) and destructive (pit craters; caldera collapse) phenomena. Piton de la Fournaise (PdF) shield volcano (La Réunion Island, Indian Ocean) is an ideal place to study these differences in eruptive behaviour. Besides the frequent eruptions in the central Enclos Fouqué caldera, hundreds of eruptive vents opened along three main rift zones cutting the edifice during the last 50 kyrs. Two short rift zones are characterized by weak seismicity and lateral magma transport at shallow depth (above sea level). Here we focus on the third and largest rift zone (15km wide, 20 km long), which extends in a north-westerly direction between PdF and nearby Piton des Neiges volcanic complex. It is typified by deep seismicity (up to 30 km), emitting mostly primitive magmas, testifying of high fluid pressures (up to 5 kbar) and large-volume eruptions. We present new field data (including stratigraphic logs, a geological map of the area, C-14 dating and geochemical analyses of the eruption products) on one of the youngest (~6kyrs) and largest lava field (Trous Blancs eruption). It extends for 24km from a height of 1800 m asl, passing Le Tampon and Saint Pierre cities, until reaching the coast. The source area of this huge lava flow has been identified in an alignment of four previously unidentified pit craters. The eruption initiated with intense fountaining activity, producing a m-thick bed of loose black scoria, which becomes densely welded in its upper part; followed by an alternation of volume rich lava effusions and strombolian activity, resulting in the emplacement of meter-thick, massive units of olivine-basalt alternating with coarse scoria beds in the proximal area. Activity ended with the emplacement of a dm-thick bed of glassy, dense scoria and a stratified lithic

  2. Volcanic Eruptions and Climate

    Science.gov (United States)

    LeGrande, Allegra N.; Anchukaitis, Kevin J.

    2015-01-01

    Volcanic eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, volcanic eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.

  3. The TF1 Radio Astronomy Working Group in the Andean ROAD: goals and challenges for 2025

    Science.gov (United States)

    Chaparro Molano, G.

    2017-07-01

    Since the creation of the Andean Regional Office of Astronomy for Development (OAD) of the International Astronomical Union, one of the main goals has been to foster a scientific culture of radio astronomy in countries of the central and northern Andes (Bolivia, Colombia, Ecuador, Perú, and Venezuela). For this reason, Andean ROAD Task Force 1 (Research and Education in Universities) created the Radio Astronomy Working Group to set a path along which collaborative endeavors can grow and yield scientific results. The first official meeting of the Working Group took place in Bogotá, Colombia during the 2nd Astronomá en los Andes Workshop (2015) where scientists actively developing projects in radio astronomy set goals for the near future, such as improving mobility for researchers and students, developing collaborations in related areas such as engineering and data science, and building transnational collaborations aiming at developing VLBI across the countries of the Andean ROAD and beyond. In this poster, I present current projects and associated research groups (ROAS - Perú, SiAMo - Colombia, Alfa-Orion UTP - Colombia, RAIG - Chile) and discuss goalposts and current challenges in the development of transnational radioastronomical projects. As a case study, I present the development and early astronomical results of the privately funded UECCI 4m Radio Telescope for 21 cm line observations in Bogotá, Colombia.

  4. Adding seismic broadband analysis to characterize Andean backarc seismicity in Argentina

    Science.gov (United States)

    Alvarado, P.; Giuliano, A.; Beck, S.; Zandt, G.

    2007-05-01

    Characterization of the highly seismically active Andean backarc is crucial for assessment of earthquake hazards in western Argentina. Moderate-to-large crustal earthquakes have caused several deaths, damage and drastic economic consequences in Argentinean history. We have studied the Andean backarc crust between 30°S and 36°S using seismic broadband data available from a previous ("the CHARGE") IRIS-PASSCAL experiment. We collected more than 12 terabytes of continuous seismic data from 22 broadband instruments deployed across Chile and Argentina during 1.5 years. Using free software we modeled full regional broadband waveforms and obtained seismic moment tensor inversions of crustal earthquakes testing for the best focal depth for each event. We also mapped differences in the Andean backarc crustal structure and found a clear correlation with different types of crustal seismicity (i.e. focal depths, focal mechanisms, magnitudes and frequencies of occurrence) and previously mapped terrane boundaries. We now plan to use the same methodology to study other regions in Argentina using near-real time broadband data available from the national seismic (INPRES) network and global seismic networks operating in the region. We will re-design the national seismic network to optimize short-period and broadband seismic station coverage for different network purposes. This work is an international effort that involves researchers and students from universities and national government agencies with the goal of providing more information about earthquake hazards in western Argentina.

  5. Structural control on arc volcanism: The Caviahue Copahue complex, Central to Patagonian Andes transition (38°S)

    Science.gov (United States)

    Melnick, Daniel; Folguera, Andrés; Ramos, Victor A.

    2006-11-01

    This paper describes the volcanostratigraphy, structure, and tectonic implications of an arc volcanic complex in an oblique subduction setting: the Caviahue caldera Copahue volcano (CAC) of the Andean margin. The CAC is located in a first-order morphotectonic transitional zone, between the low and narrow Patagonian and the high and broad Central Andes. The evolution of the CAC started at approximately 4-3 Ma with the opening of the 20 × 15 km Caviahue pull-apart caldera; Las Mellizas volcano formed inside the caldera and collapsed at approximately 2.6 Ma; and the Copahue volcano evolved in three stages: (1) 1.2-0.7 Ma formed the approximately 1 km thick andesitic edifice, (2) 0.7-0.01 Ma erupted andesitic-dacitic subglacial pillow lavas, and (3) 0.01-0 Ma erupted basaltic-andesites and pyroclastic flows from fissures, aligned cones, and summit craters. Magma ascent has occurred along planes perpendicular to the least principal horizontal stress, whereas hydrothermal activity and hot springs also occur along parallel planes. At a regional scale, Quaternary volcanism concentrates along the NE-trending, 90 km long Callaqui-Copahue-Mandolegüe lineament, the longest of the southern volcanic zone, which is here interpreted as an inherited crustal-scale transfer zone from a Miocene rift basin. At a local scale within the CAC, effusions are controlled by local structures that formed at the intersection of regional fault systems. The Central to Patagonian Andes transition occurs at the Callaqui-Copahue-Mandolegüe lineament, which decouples active deformation from the intra-arc strike-slip Liquiñe-Ofqui fault zone to the south and the backarc Copahue-Antiñir thrust system.

  6. Volcanic stratigraphy: A review

    Science.gov (United States)

    Martí, Joan; Groppelli, Gianluca; Brum da Silveira, Antonio

    2018-05-01

    Volcanic stratigraphy is a fundamental component of geological mapping in volcanic areas as it yields the basic criteria and essential data for identifying the spatial and temporal relationships between volcanic products and intra/inter-eruptive processes (earth-surface, tectonic and climatic), which in turn provides greater understanding of the geological evolution of a region. Establishing precise stratigraphic relationships in volcanic successions is not only essential for understanding the past behaviour of volcanoes and for predicting how they might behave in the future, but is also critical for establishing guidelines for exploring economic and energy resources associated with volcanic systems or for reconstructing the evolution of sedimentary basins in which volcanism has played a significant role. Like classical stratigraphy, volcanic stratigraphy should also be defined using a systematic methodology that can provide an organised and comprehensive description of the temporal and spatial evolution of volcanic terrain. This review explores different methods employed in studies of volcanic stratigraphy, examines four case studies that use differing stratigraphic approaches, and recommends methods for using systematic volcanic stratigraphy based on the application of the concepts of traditional stratigraphy but adapted to the needs of volcanological environment.

  7. Soft sediment deformation structures in a lacustrine sedimentary succession induced by volcano-tectonic activities: An example from the Cretaceous Beolgeumri Formation, Wido Volcanics, Korea

    Science.gov (United States)

    Ko, Kyoungtae; Kim, Sung Won; Lee, Hong-Jin; Hwang, In Gul; Kim, Bok Chul; Kee, Won-Seo; Kim, Young-Seog; Gihm, Yong Sik

    2017-08-01

    The Cretaceous Beolgeumri Formation is composed of laminated mudstones intercalated with sandstones, chert, and a bed of lapilli tuff that were deposited in a lacustrine environment at the terminal part of a regional strike-slip fault systems on the southwestern Korean Peninsula. The Beolgeumri Formation contains various types of soft sediment deformation (SSD) structures that are characterized by a wide extent (features and deformation styles: 1) fold structures, 2) load structures, 3) water-escape structures, 4) rip-down structures, 5) boudin structures, and 6) synsedimentary fault structures. Field examination of SSD structures together with an analysis of the sedimentological records of the Beolgeumri Formation indicate that the SSD structures formed largely by liquefaction and/or fluidization triggered by ground shaking during earthquakes. To constrain the timing of the development of SSD structures in the Beolgeumri Formation, we conducted sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon age dating of block sized lithic clasts bearing volcaniclastic deposits that conformably underlie (the Mangryeongbong Tuff) and overlie (the Ttandallae Tuff) the Beolgeumri Formation. The Mangryeongbong and Ttandallae Tuffs have ages of 86.63 ± 0.83 Ma and 87.24 ± 0.36 Ma, respectively, indicating that the Beolgeumri Formation was deposited during a short interval between major volcanic eruptions. The large lithic clasts of volcaniclastic deposits suggest that the Beolgeumri Formation was deposited adjacent to an active volcanic edifice(s). Syndepositional magmatic activities are suggested by the occurrence of a lapilli tuff bed in the Beolgeumri Formation and an igneous intrusion (intermediate sill) that is crosscut by a sand dike, as well as the similar age results of the underlying and overlying volcaniclastic deposits. Thus, we infer that the earthquakes that caused the development of SSD structures in the study area were closely related to syndepositional

  8. Characterization of Two Microbial Isolates from Andean Lakes in Bolivia

    Science.gov (United States)

    Demergasso, C.; Blamey, J.; Escudero, L.; Chong, G.; Casamayor, E. O.; Cabrol, N. A.; Grin, E. A.; Hock, A.; Kiss, A.; Borics, G.

    2004-01-01

    We are currently investigating the biological population present in the highest and least explored perennial lakes on earth in the Bolivian and Chilean Andes, including several volcanic crater lakes of more than 6000 m elevation, in combination of microbiological and molecular biological methods. Our samples were collected in saline lakes of the Laguna Blanca Laguna Verde area in the Bolivian Altiplano and in the Licancabur volcano crater (27 deg. 47 min S/67 deg. 47 min. W) in the ongoing project studying high altitude lakes. The main goal of the project is to look for analogies with Martian paleolakes. These Bolivian lakes can be described as Andean lakes following the classification of Chong. We have attempted to isolate pure cultures and phylogenetically characterize prokaryotes that grew under laboratory conditions. Sediment samples taken from the Licancabur crater lake (LC), Laguna Verde (LV), and Laguna Blanca (LB) were analyzed and cultured using enriched liquid media under both aerobic and anaerobic conditions. All cultures were incubated at room temperature (15 to 20 C) and under light exposure. For the reported isolates, 36 hours incubation were necessary for reaching optimal optical densities to consider them viable cultures. Ten serial dilutions starting from 1% inoculum were required to obtain a suitable enriched cell culture to transfer into solid media. Cultures on solid medium were necessary to verify the formation of colonies in order to isolate pure cultures. Different solid media were prepared using several combinations of both trace minerals and carbohydrates sources in order to fit their nutrient requirements. The microorganisms formed individual colonies on solid media enriched with tryptone, yeast extract and sodium chloride. Cells morphology was studied by optical and electronic microscopy. Rodshape morphologies were observed in most cases. Total bacterial genomic DNA was isolated from 50 ml late-exponential phase culture by using the CTAB

  9. Recurrence models of volcanic events: Applications to volcanic risk assessment

    International Nuclear Information System (INIS)

    Crowe, B.M.; Picard, R.; Valentine, G.; Perry, F.V.

    1992-01-01

    An assessment of the risk of future volcanism has been conducted for isolation of high-level radioactive waste at the potential Yucca Mountain site in southern Nevada. Risk used in this context refers to a combined assessment of the probability and consequences of future volcanic activity. Past studies established bounds on the probability of magmatic disruption of a repository. These bounds were revised as additional data were gathered from site characterization studies. The probability of direct intersection of a potential repository located in an eight km 2 area of Yucca Mountain by ascending basalt magma was bounded by the range of 10 -8 to 10 -10 yr -1 2 . The consequences of magmatic disruption of a repository were estimated in previous studies to be limited. The exact releases from such an event are dependent on the strike of an intruding basalt dike relative to the repository geometry, the timing of the basaltic event relative to the age of the radioactive waste and the mechanisms of release and dispersal of the waste radionuclides in the accessible environment. The combined low probability of repository disruption and the limited releases associated with this event established the basis for the judgement that the risk of future volcanism was relatively low. It was reasoned that that risk of future volcanism was not likely to result in disqualification of the potential Yucca Mountain site

  10. Tracking spatial variation in river load from Andean highlands to inter-Andean valleys

    Science.gov (United States)

    Tenorio, Gustavo E.; Vanacker, Veerle; Campforts, Benjamin; Álvarez, Lenín; Zhiminaicela, Santiago; Vercruysse, Kim; Molina, Armando; Govers, Gerard

    2018-05-01

    Mountains play an important role in the denudation of continents and transfer erosion and weathering products to lowlands and oceans. The rates at which erosion and weathering processes take place in mountain regions have a substantial impact on the morphology and biogeochemistry of downstream reaches and lowlands. The controlling factors of physical erosion and chemical weathering and the coupling between the two processes are not yet fully understood. In this study, we report physical erosion and chemical weathering rates for five Andean catchments located in the southern Ecuadorian Andes and investigate their mutual interaction. During a 4-year monitoring period, we sampled river water at biweekly intervals, and we analyzed water samples for major ions and suspended solids. We derived the total annual dissolved, suspended sediment, and ionic loads from the flow frequency curves and adjusted rating curves and used the dissolved and suspended sediment yields as proxies for chemical weathering and erosion rates. In the 4-year period of monitoring, chemical weathering exceeds physical erosion in the high Andean catchments. Whereas physical erosion rates do not exceed 30 t km-2 y-1 in the relict glaciated morphology, chemical weathering rates range between 22 and 59 t km-2 y-1. The variation in chemical weathering is primarily controlled by intrinsic differences in bedrock lithology. Land use has no discernible impact on the weathering rate but leads to a small increase in base cation concentrations because of fertilizer leaching in surface water. When extending our analysis with published data on dissolved and suspended sediment yields from the northern and central Andes, we observe that the river load composition strongly changes in the downstream direction, indicating large heterogeneity of weathering processes and rates within large Andean basins.

  11. Origins of The Paleolandslide of Tarapaca (north Chile, Andean Belt)

    Science.gov (United States)

    Darrozes, J.; Pinto, L.; Ingles, J.; Soula, J.-C.; Maire, E.; Courjault-Radé, P.; Hérail, G.

    Landslides are an important and potentially rate-limiting process in the topographic evolution of active orogens like the Andean Belt. Various processes are responsi- ble for triggering landslides, including hillslope baselevel lowering, seismic events (Keefer, 1999); climate changes (Coriminas and Moya, 1999), anthropic effects (Sah and Mazari, 1998) and each of these triggers may be spatially heterogeneous in strength and effectiveness. Present work seeks to identify and constrain the domi- nant mechanism of a Tarapaca PaleoLandslide in order to determine the influence of the overall tectonic uplift of the Andean belt, and the seismicity of the area. The zone of interest is located near Iquique, along the Atacama Desert in the Tarapaca (N. Chile) domain (1955S, 6935W). The climate of the region became dry at 15 Ma (Gregory-Wodzicki, 2000) and remain today one of driest in the world. One of the most significant characteristic of the Atacama Desert landslides is to be located on the western limb of N-S trending flexures. At Tarapaca, the studied landslide is located on the front limb of a fault propagation anticline, the Moquella flexure, of Cenozoic age. The slope in this part increases weakly to reach a value close to 10 degrees. The main scarp of Tarapaca landslide has a length of ≈ 7 km and an elevation close to 200 m. This corresponds to the thickness of an ignimbritic formation which constitutes the load of the landslide. As in most of the Atacama desert, the lateral boundaries of the landslide are two antecedent paleorivers (Suca &Lataguella) which created free edges to the landslide and thus greatly facilitating landsliding. A smaller secondary landslide formed in the foot zone because of the local increase in the slope, which was responsible for the instability of the overlapping mass. The analysis of the safety factor and morphologic features shows that weathering, uplift, water pressure and load are not enough important for creating the slide. It is

  12. Volcanic Characteristics of Kueishantao in Northeast Taiwan and Their Implications

    Directory of Open Access Journals (Sweden)

    Ching-Lung Chiu

    2010-01-01

    Full Text Available Kueishantao (KST is a small offshore volcanic island located at the southernmost part of the Okinawa Trough. In this study, we conducted a detailed mapping incorporating the new high resolution LiDAR DTM laser scanning device to accurately construct a volcanic sequence. A new 1/5000 geological map was established. One primary volcanic cone, composed of layers of both lava flows and pyroclastic rocks constituted the major edifice of KST. The other minor volcanic cone, which consists of volcanic lapillis and blocks, is seated to the east of the main cone. The escarped and nearly straight coast in the southern part of the KST indicates that the volcano suffered a large post-volcanic edifice collapse erasing nearly one half of the volume of both volcanic cones. The increase in the abundance of the xenoliths of sedimentary rocks from the lower to the upper part of the volcanic sequence indicates that the formation of volcanic rocks of the KST involved an intensification of crustal contamination. The possibility of volcanic eruption can not be excluded in the future based on the present thermolu¬minescene age data of 7 ka. The associated eruptive ash fall and tsunami induced by the further collapse of the KST volcanic edifice might have great influence to the adjacent inland. Thus, long-term monitoring of volcanic activities around KST should be required for future hazard assessments.

  13. Volcanic Alert System (VAS) developed during the (2011-2013) El Hierro (Canary Islands) volcanic process

    Science.gov (United States)

    Ortiz, Ramon; Berrocoso, Manuel; Marrero, Jose Manuel; Fernandez-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Garcia, Alicia

    2014-05-01

    In volcanic areas with long repose periods (as El Hierro), recently installed monitoring networks offer no instrumental record of past eruptions nor experience in handling a volcanic crisis. Both conditions, uncertainty and inexperience, contribute to make the communication of hazard more difficult. In fact, in the initial phases of the unrest at El Hierro, the perception of volcanic risk was somewhat distorted, as even relatively low volcanic hazards caused a high political impact. The need of a Volcanic Alert System became then evident. In general, the Volcanic Alert System is comprised of the monitoring network, the software tools for the analysis of the observables, the management of the Volcanic Activity Level, and the assessment of the threat. The Volcanic Alert System presented here places special emphasis on phenomena associated to moderate eruptions, as well as on volcano-tectonic earthquakes and landslides, which in some cases, as in El Hierro, may be more destructive than an eruption itself. As part of the Volcanic Alert System, we introduce here the Volcanic Activity Level which continuously applies a routine analysis of monitoring data (particularly seismic and deformation data) to detect data trend changes or monitoring network failures. The data trend changes are quantified according to the Failure Forecast Method (FFM). When data changes and/or malfunctions are detected, by an automated watchdog, warnings are automatically issued to the Monitoring Scientific Team. Changes in the data patterns are then translated by the Monitoring Scientific Team into a simple Volcanic Activity Level, that is easy to use and understand by the scientists and technicians in charge for the technical management of the unrest. The main feature of the Volcanic Activity Level is its objectivity, as it does not depend on expert opinions, which are left to the Scientific Committee, and its capabilities for early detection of precursors. As a consequence of the El Hierro

  14. The Volcanism Ontology (VO): a model of the volcanic system

    Science.gov (United States)

    Myer, J.; Babaie, H. A.

    2017-12-01

    We have modeled a part of the complex material and process entities and properties of the volcanic system in the Volcanism Ontology (VO) applying several top-level ontologies such as Basic Formal Ontology (BFO), SWEET, and Ontology of Physics for Biology (OPB) within a single framework. The continuant concepts in BFO describe features with instances that persist as wholes through time and have qualities (attributes) that may change (e.g., state, composition, and location). In VO, the continuants include lava, volcanic rock, and volcano. The occurrent concepts in BFO include processes, their temporal boundaries, and the spatio-temporal regions within which they occur. In VO, these include eruption (process), the onset of pyroclastic flow (temporal boundary), and the space and time span of the crystallization of lava in a lava tube (spatio-temporal region). These processes can be of physical (e.g., debris flow, crystallization, injection), atmospheric (e.g., vapor emission, ash particles blocking solar radiation), hydrological (e.g., diffusion of water vapor, hot spring), thermal (e.g., cooling of lava) and other types. The properties (predicates) relate continuants to other continuants, occurrents to continuants, and occurrents to occurrents. The ontology also models other concepts such as laboratory and field procedures by volcanologists, sampling by sensors, and the type of instruments applied in monitoring volcanic activity. When deployed on the web, VO will be used to explicitly and formally annotate data and information collected by volcanologists based on domain knowledge. This will enable the integration of global volcanic data and improve the interoperability of software that deal with such data.

  15. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    to eruption behaviour and during ascent magma behaves in an increasingly rock-like manner as it degasses and crystallises. This character aids the development of shear zones in the conduit, producing fault surfaces that host gouge, cataclasite and pseudotachylyte and which control the last hundreds of meters of ascent by frictional slip. Recent work has shown that the occurrence of vesiculation of gas bubbles modifies the rheology of frictional melt and in extreme cases can trigger eruption style to switch from effusive to explosive activity. Hence it is of vital importance to recognise the frictional behaviour of volcanic rocks and magmas to understand the continuation of an eruption and associated hazards.

  16. Environment, vulnerability, and gender in Andean ethnomedicine.

    Science.gov (United States)

    Larme, A C

    1998-10-01

    In Cuyo Cuyo, in the southern Peruvian highlands, ethnomedicine is rife with images of human vulnerability to a hostile and unpredictable environment. This is represented in the ethnomedical system by a focus on wayras, air- or wind-borne illnesses that enter through vulnerable body openings such as the head, orifices, lower back, and feet. Women are viewed to be more vulnerable, or débil, than men to illness because they have an extra orifice, the vagina, they lose copious amounts of blood, which is thought to be irreplaceable, during childbirth. and because they suffer more negative emotions, which are thought to attract wayras and other illnesses to the body. The relationship of ethnomedical beliefs to the Andean physical and political economic environment is explored within the context of social and economic change. Negative beliefs about women's bodies have negative effects on women's roles and position vis-à-vis men in present day Cuyo Cuyo. Ethnomedical beliefs reflect and reinforce gender inequalities in present day Peru and are part of a cultural ideology that in general devalues women. This case study demonstrates that power is a key dimension in the cultural construction of medical knowledge. whether in non-Western or Western societies.

  17. An Overview of the Dynamics of the Volcanic Paroxysmal Explosive Activity, and Related Seismicity, at Andesitic and Dacitic Volcanoes (1960–2010

    Directory of Open Access Journals (Sweden)

    Vyacheslav M. Zobin

    2018-05-01

    Full Text Available Understanding volcanic paroxysmal explosive activity requires the knowledge of many associated processes. An overview of the dynamics of paroxysmal explosive eruptions (PEEs at andesitic and dacitic volcanoes occurring between 1960 and 2010 is presented here. This overview is based mainly on a description of the pre-eruptive and eruptive events, as well as on the related seismic measurements. The selected eruptions are grouped according to their Volcanic Explosivity Index (VEI. A first group includes three eruptions of VEI 5-6 (Mount St. Helens, 1980; El Chichón, 1982; Pinatubo, 1991 and a second group includes three eruptions of VEI 3 (Usu volcano, 1977; Soufriere Hills Volcano (SHV, 1996, and Volcán de Colima, 2005. The PEEs of the first group have similarity in their developments that allows to propose a 5-stage scheme of their dynamics process. Between these stages are: long (more than 120 years period of quiescence (stage 1, preliminary volcano-tectonic (VT earthquake swarm (stage 2, period of phreatic explosions (stage 3 and then, PEE appearance (stage 4. It was shown also that the PEEs of this group during their Plinian stage “triggered” the earthquake sequences beneath the volcanic structures with the maximum magnitude of earthquakes proportional to the volume of ejecta of PEEs (stage 5. Three discussed PEEs of the second group with lower VEI developed in more individual styles, not keeping within any general scheme. Among these, one PEE (SHV may be considered as partly following in development to the PEEs of the first group, having stages 1, 3, and 4. The PEEs of Usu volcano and of Volcán de Colima had no preliminary long-term stages of quiescence. The PEE at Usu volcano came just at the end of the preceding short swarm of VT earthquakes. At Volcán de Colima, no preceding swarm of VT occurred. This absence of any regularity in development of lower VEI eruptions may refer, among other reasons, to different conditions of opening

  18. Continuous magma recharge at Mt. Etna during the 2011-2013 period controls the style of volcanic activity and compositions of erupted lavas

    Science.gov (United States)

    Viccaro, Marco; Calcagno, Rosario; Garozzo, Ileana; Giuffrida, Marisa; Nicotra, Eugenio

    2015-02-01

    Volcanic rocks erupted during the January 2011 - April 2013 paroxysmal sequence at Mt. Etna volcano have been investigated through in situ microanalysis of mineral phases and whole rock geochemistry. These products have been also considered within the framework of the post-2001 record, evidencing that magmas feeding the 2011-2013 paroxysmal activity inherited deep signature comparable to that of the 2007-2009 volcanic rocks for what concerns their trace element concentration. Analysis performed on plagioclase, clinopyroxene and olivine, which are sensitive to differentiation processes, show respectively fluctuations of the An, Mg# and Fo contents during the considered period. Also major and trace elements measured on the whole rock provide evidence of the evolutionary degree variations through time. Simulations by MELTS at fixed chemical-physical parameters allowed the definition of feeding system dynamics controlling the geochemical variability of magmas during the 2011-2013 period. Specifically, compositional changes have been interpreted as due to superimposition of fractional crystallization and mixing in variable proportions with more basic magma ascending from intermediate to shallower levels of the plumbing system. Composition of the recharging end-member is compatible with that of the most basic magmas emitted during the 2007 and the early paroxysmal eruptions of 2012. Analysis of the erupted volumes of magma combined with its petrologic evolution through time support the idea that large volumes of magma are continuously intruded and stored in the intermediate plumbing system after major recharging phases in the deepest levels of it. Transient recharge from the intermediate to the shallow levels is then responsible for the paroxysmal eruptions.

  19. Early Jurassic Volcanism in the South Lhasa Terrane, Southern Tibet: Record of Back-arc Extension in the Active Continental Margin

    Science.gov (United States)

    Wei, Y.; Zhao, Z.; Zhu, D. C.; Wang, Z.; Liu, D.; Mo, X.

    2015-12-01

    Indus-Yarlung Zangbo Suture Zone (IYZSZ) represents the Mesozoic remnants of the Neo-Tethyan Ocean lithosphere after its northward subduction beneath the Lhasa Terrane. The evolution of the Neo-Tethyan Ocean prior to India-Asia collision remains unclear. To explore this period of history, we investigate zircon U-Pb geochronology, geochemistry and Nd-Hf isotopes of the Early Jurassic bimodal-like volcanic sequence around Dagze area, south Tibet. The volcanic sequence comprises calc-alkaline basalts to rhyolites whereas intermediate components are volumetrically restricted. Zircons from a basaltic andesite yielded crystallization age of 178Ma whereas those from 5 silicic rocks were dated at 183-174Ma, which suggest that both the basaltic and the silicic rocks are coeval. The basaltic rocks are enriched in LREE and LILE, and depleted in HFSE, with Epsilon Nd(t) of 1.6-4.0 and zircon Epsilon Hf(t) of 0.7-11.8, which implies that they were derived from a heterogenetic mantle source metasomatized by subduction components. Trace element geochemistry shows that the basaltic rocks are compositionally transitional from normal mid-ocean ridge basalts (N-MORB) to island arc basalts (IAB, e.g. Zedong arc basalts of ~160-155Ma in the south margin of Lhasa Terrane), with the signature of immature back-arc basin basalts. The silicic rocks display similar Nd-Hf isotopic features of the Gangdese batholith with Epsilon Nd(t) of 0.9-3.4 and zircon Epsilon Hf(t) of 2.4-17.7, indicating that they were possibly generated by anatexis of basaltic juvenile lower crust, instead of derived from the basaltic magma. These results support an Early to Middle Jurassic (183-155Ma) model that the back-arc extension tectonic setting were existing in the active continental margin in the south Lhasa Terrane.

  20. On the Nature of Cross-Linguistic Transfer: A Case Study of Andean Spanish

    Science.gov (United States)

    Muntendam, Antje G.

    2013-01-01

    This paper presents the results of a study on cross-linguistic transfer in Andean Spanish word order. In Andean Spanish the object appears in preverbal position more frequently than in non-Andean Spanish, which has been attributed to an influence from Quechua (a Subject-Object-Verb language). The high frequency of preverbal objects could be…

  1. Seismic tomography model reveals mantle magma sources of recent volcanic activity at El Hierro Island (Canary Islands, Spain)

    Science.gov (United States)

    García-Yeguas, Araceli; Ibáñez, Jesús M.; Koulakov, Ivan; Jakovlev, Andrey; Romero-Ruiz, M. Carmen; Prudencio, Janire

    2014-12-01

    We present a 3-D model of P and S velocities beneath El Hierro Island, constructed using the traveltime data of more than 13 000 local earthquakes recorded by the Instituto Geográfico Nacional (IGN, Spain) in the period from 2011 July to 2012 September. The velocity models were performed using the LOTOS code for iterative passive source tomography. The results of inversion were thoroughly verified using different resolution and robustness tests. The results reveal that the majority of the onshore area of El Hierro is associated with a high-velocity anomaly observed down to 10-12-km depth. This anomaly is interpreted as the accumulation of solid igneous rocks erupted during the last 1 Myr and intrusive magmatic bodies. Below this high-velocity pattern, we observe a low-velocity anomaly, interpreted as a batch of magma coming from the mantle located beneath El Hierro. The boundary between the low- and high-velocity anomalies is marked by a prominent seismicity cluster, thought to represent anomalous stresses due to the interaction of the batch of magma with crust material. The areas of recent eruptions, Orchilla and La Restinga, are associated with low-velocity anomalies surrounding the main high-velocity block. These eruptions took place around the island where the crust is much weaker than the onshore area and where the melted material cannot penetrate. These results put constraints on the geological model that could explain the origin of the volcanism in oceanic islands, such as in the Canaries, which is not yet clearly understood.

  2. Superficial alteration mineralogy in active volcanic systems: An example of Poás volcano, Costa Rica

    Science.gov (United States)

    Rodríguez, Alejandro; van Bergen, Manfred J.

    2017-10-01

    volcanic environments.

  3. A volcanic activity alert-level system for aviation: review of its development and application in Alaska

    Science.gov (United States)

    Guffanti, Marianne; Miller, Thomas P.

    2013-01-01

    An alert-level system for communicating volcano hazard information to the aviation industry was devised by the Alaska Volcano Observatory (AVO) during the 1989–1990 eruption of Redoubt Volcano. The system uses a simple, color-coded ranking that focuses on volcanic ash emissions: Green—normal background; Yellow—signs of unrest; Orange—precursory unrest or minor ash eruption; Red—major ash eruption imminent or underway. The color code has been successfully applied on a regional scale in Alaska for a sustained period. During 2002–2011, elevated color codes were assigned by AVO to 13 volcanoes, eight of which erupted; for that decade, one or more Alaskan volcanoes were at Yellow on 67 % of days and at Orange or Red on 12 % of days. As evidence of its utility, the color code system is integrated into procedures of agencies responsible for air-traffic management and aviation meteorology in Alaska. Furthermore, it is endorsed as a key part of globally coordinated protocols established by the International Civil Aviation Organization to provide warnings of ash hazards to aviation worldwide. The color code and accompanying structured message (called a Volcano Observatory Notice for Aviation) comprise an effective early-warning message system according to the United Nations International Strategy for Disaster Reduction. The aviation color code system currently is used in the United States, Russia, New Zealand, Iceland, and partially in the Philippines, Papua New Guinea, and Indonesia. Although there are some barriers to implementation, with continued education and outreach to Volcano Observatories worldwide, greater use of the aviation color code system is achievable.

  4. Evidences of Episodic Crustal Magmatic Diapir and Shallow Volcanic Activity at Uturuncu, Central Andes, from Geodetic Observations between 2014 - 2017

    Science.gov (United States)

    Lau, H. N.; Tymofyeyeva, E.; Fialko, Y. A.

    2017-12-01

    Previous space geodetic studies using ERS-1/2 and Envisat Interferometric Synthetic Aperture Radar (InSAR) data revealed a broad uplift of 10 mm/yr within the Altiplano-Puna Volcanic Complex (APVC), centered at the Uturuncu volcano, surrounded by a ring of subsidence at a rate of a few millimeters per year. This pattern was attributed to formation of a diapir in the middle of the Altiplano-Puna Magma Body (APMB), at depth of 15-19 km. We use new data from the Sentinel-1 InSAR mission, collected between 2014-2017, to produce high-resolution maps of surface displacements in the satellite's line of sight (LOS) from 4 satellite tracks. We estimated random propagation effects (e.g. due to atmospheric turbulence) using a common-point stacking method by Tymofyeyeva and Fialko [2015] and estimated temporally-correlated propagation effects (e.g. due to seasonal variations in atmospheric moisture) using a regression of the residual phase against topography. The estimated atmospheric artifacts were removed from the interferograms prior to computing the time series of the LOS displacements. The data indicate that the uplift above the APMB has considerably slowed down compared to the 1992-2010 epoch. The observed variations in the uplift rate suggest that the "ballooning" of the mid-crustal diapir is episodic on time scales of year to decades, possibly due to variations in melt supply from the partially molten APMB to the incipient diapir. We also find a previously undiscovered localized uplift 11 km south of Uturuncu's peak with maximum LOS velocities of 10 - 15 mm/yr. Joint inversions of data from different satellite tracks for a point source of inflation in an elastic half space constrain the source depth to be at 2 km, suggestive of a shallow magma chamber or a hydrothermal system.

  5. Volcanic activity at Etna volcano, Sicily, Italy between June 2011 and March 2017 studied with TanDEM-X SAR interferometry

    Science.gov (United States)

    Kubanek, J.; Raible, B.; Westerhaus, M.; Heck, B.

    2017-12-01

    High-resolution and up-to-date topographic data are of high value in volcanology and can be used in a variety of applications such as volcanic flow modeling or hazard assessment. Furthermore, time-series of topographic data can provide valuable insights into the dynamics of an ongoing eruption. Differencing topographic data acquired at different times enables to derive areal coverage of lava, flow volumes, and lava extrusion rates, the most important parameters during ongoing eruptions for estimating hazard potential, yet most difficult to determine. Anyhow, topographic data acquisition and provision is a challenge. Very often, high-resolution data only exists within a small spatial extension, or the available data is already outdated when the final product is provided. This is especially true for very dynamic landscapes, such as volcanoes. The bistatic TanDEM-X radar satellite mission enables for the first time to generate up-to-date and high-resolution digital elevation models (DEMs) repeatedly using the interferometric phase. The repeated acquisition of TanDEM-X data facilitates the generation of a time-series of DEMs. Differencing DEMs generated from bistatic TanDEM-X data over time can contribute to monitor topographic changes at active volcanoes, and can help to estimate magmatic ascent rates. Here, we use the bistatic TanDEM-X data to investigate the activity of Etna volcano in Sicily, Italy. Etna's activity is characterized by lava fountains and lava flows with ash plumes from four major summit crater areas. Especially the newest crater, the New South East Crater (NSEC) that was formed in 2011 has been highly active in recent years. Over one hundred bistatic TanDEM-X data pairs were acquired between January 2011 and March 2017 in StripMap mode, covering episodes of lava fountaining and lava flow emplacement at Etna's NSEC and its surrounding area. Generating DEMs of every bistatic data pair enables us to assess areal extension of the lava flows, to

  6. 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

  7. Aquatic community response to volcanic eruptions on the Ecuadorian Andean flank: evidence from the palaeoecological record

    NARCIS (Netherlands)

    Matthews-Bird, F.; Brooks, S.J.; Gosling, W.D.; Gulliver, P.; Mothes, P.; Montoya, E.

    2017-01-01

    Aquatic ecosystems in the tropical Andes are under increasing pressure from human modification of the landscape (deforestation and dams) and climatic change (increase of extreme events and 1.5 °C on average temperatures are projected for AD 2100). However, the resilience of these ecosystems to

  8. Volcanic hazards in Central America

    Science.gov (United States)

    Rose, William I.; Bluth, Gregg J.S.; Carr, Michael J.; Ewert, John W.; Patino, Lina C.; Vallance, James W.

    2006-01-01

    This volume is a sampling of current scientific work about volcanoes in Central America with specific application to hazards. The papers reflect a variety of international and interdisciplinary collaborations and employ new methods. The book will be of interest to a broad cross section of scientists, especially volcanologists. The volume also will interest students who aspire to work in the field of volcano hazards mitigation or who may want to work in one of Earth’s most volcanically active areas.

  9. The rigid Andean sliver hypothesis challenged : impact on interseismic coupling on the Chilean subduction zone

    Science.gov (United States)

    Metois, M.

    2017-12-01

    Convergence partitioning between subduction zones and crustal active structures has been widely evidenced. For instance, the convergence between the Indian and Sunda plates is accommodated both by the Sumatra subduction zone and the Great Sumatran strike-slip fault, that defines a narrow sliver. In Cascadia, small-scale rotating rigid blocks bounded by active faults have been proposed (e.g. McCaffrey et al. 2007). Recent advances in geodetic measurements along the South-American margin especially in Ecuador, Peru and Chile and the need for precise determination of the coupling amount on the megathrust interface in particular for seismic hazard assessment, led several authors to propose the existence of large-scale Andean slivers rotating clockwise and counter-clockwise South and North of the Arica bend, respectively (e.g. Chlieh et al. 2011, Nocquet et al. 2014, Métois et al. 2013). In Chile, one single large Andean sliver bounded to the west by the subduction thrust and to the east by the subandean fold-an-thrust belt active front is used to mimic the velocities observed in the middle to far field that are misfitted by elastic coupling models on the megathrust interface alone (Métois et al. 2016). This rigid sliver is supposed to rotate clockwise around a Euler pole located in the South Atlantic ocean, consistently with long-term observed rotations detected by paleomagnetism (e.g. Arriagada et al. 2008). However, recent GPS data acquired in the Taltal area ( 26°S, Klein et al. submitted) show higher than expected middle-field eastward velocities and question the first-order assumption of a rigid Andean sliver. Mis-modeling the fore-arc deformation has a direct impact on the inverted coupling amount and distribution, and could therefore bias significantly the megathrust rupture scenarios. Correctly estimating the current-day deformation of the Andes is therefore required to properly assess for coupling on the plate interface and is challenging since crustal

  10. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.

    2009-08-22

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean integrates volcanic radiative cooling and responds over a wide range of time scales. The associated processes, especially ocean heat uptake, play a key role in ongoing climate change. However, they are not well constrained by observations, and attempts to simulate them in current climate models used for climate predictions yield a range of uncertainty. Volcanic impacts on the ocean provide an independent means of assessing these processes. This study focuses on quantification of the seasonal to multidecadal time scale response of the ocean to explosive volcanism. It employs the coupled climate model CM2.1, developed recently at the National Oceanic and Atmospheric Administration\\'s Geophysical Fluid Dynamics Laboratory, to simulate the response to the 1991 Pinatubo and the 1815 Tambora eruptions, which were the largest in the 20th and 19th centuries, respectively. The simulated climate perturbations compare well with available observations for the Pinatubo period. The stronger Tambora forcing produces responses with higher signal-to-noise ratio. Volcanic cooling tends to strengthen the Atlantic meridional overturning circulation. Sea ice extent appears to be sensitive to volcanic forcing, especially during the warm season. Because of the extremely long relaxation time of ocean subsurface temperature and sea level, the perturbations caused by the Tambora eruption could have lasted well into the 20th century.

  11. Macrophyte Communities of Andean Rivers: Composition and Relation with Environmental Factors

    OpenAIRE

    Alida Marcela Gómez Rodríguez; Luz Teresa Valderrama Valderrama; Carlos A. Rivera-Rondón

    2017-01-01

    Small streams of tropical Andes have been poorly studied. Therefore, there is little information about the structure, dynamics and function of their macrophyte communities. In this research, aquatic plant communities of 18 Andean streams of La Vieja (Quindío) and Otún (Risaralda) river basins were studied; those are some of the basins most affected by anthropic activities in the country. Streams were selected according to their association with the main land’s uses of the region in both basin...

  12. Can rain cause volcanic eruptions?

    Science.gov (United States)

    Mastin, Larry G.

    1993-01-01

    Volcanic eruptions are renowned for their violence and destructive power. This power comes ultimately from the heat and pressure of molten rock and its contained gases. Therefore we rarely consider the possibility that meteoric phenomena, like rainfall, could promote or inhibit their occurrence. Yet from time to time observers have suggested that weather may affect volcanic activity. In the late 1800's, for example, one of the first geologists to visit the island of Hawaii, J.D. Dana, speculated that rainfall influenced the occurrence of eruptions there. In the early 1900's, volcanologists suggested that some eruptions from Mount Lassen, Calif., were caused by the infiltration of snowmelt into the volcano's hot summit. Most such associations have not been provable because of lack of information; others have been dismissed after careful evaluation of the evidence.

  13. 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.

  14. 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.

  15. [Effects of volcanic eruptions on human health in Iceland. Review].

    Science.gov (United States)

    Gudmundsson, Gunnar; Larsen, Guðrun

    2016-01-01

    Volcanic eruptions are common in Iceland and have caused health problems ever since the settlement of Iceland. Here we describe volcanic activity and the effects of volcanic gases and ash on human health in Iceland. Volcanic gases expelled during eruptions can be highly toxic for humans if their concentrations are high, irritating the mucus membranes of the eyes and upper respiratory tract at lower concentrations. They can also be very irritating to the skin. Volcanic ash is also irritating for the mucus membranes of the eyes and upper respiratory tract. The smalles particles of volcanic ash can reach the alveoli of the lungs. Described are four examples of volcanic eruptions that have affected the health of Icelanders. The eruption of Laki volcanic fissure in 1783-1784 is the volcanic eruption that has caused the highest mortality and had the greatest effects on the well-being of Icelanders. Despite multiple volcanic eruptions during the last decades in Iceland mortality has been low and effects on human health have been limited, although studies on longterm effects are lacking. Studies on the effects of the Eyjafjallajökul eruption in 2010 on human health showed increased physical and mental symptoms, especially in those having respiratory disorders. The Directorate of Health in Iceland and other services have responded promptly to recurrent volcanic eruptions over the last few years and given detailed instructions on how to minimize the effects on the public health. Key words: volcanic eruptions, Iceland, volcanic ash, volcanic gases, health effects, mortality. Correspondence: Gunnar Guðmundsson, ggudmund@landspitali.is.

  16. On the Relationship of Dynamic Forearc Processes in Southern Peru to the Development and Preservation of Andean Topography

    Science.gov (United States)

    Hall, S. R.; Farber, D. L.; Audin, L.; Saillard, M.; Finkel, R. C.

    2008-12-01

    After more than 40 years of study, the timing and nature of Andean uplift remains an area of great scientific debate. The forearc of the Andean margin is of particular neotectonic interest, as previous models of Andean orogenesis attributed little-no Neogene deformation to the western margin of Altiplano. However, using the combination of remote sensing with high-resolution data, in situ cosmogenic isotope concentrations and thermochronology, in recent years the community has made important advances in addressing the rates, timings, styles, and locations of active deformation within the forearc of the Andean margin. To first order, we find that - both in terms of tectonics and climate - since 10Ma, the Andean forearc has been quite a dynamic region. Neotectonic studies in this region have been facilitated by the high degree of geomorphic surface preservation that the hyperarid (for at least the last 3My) coastal Atacama Desert has provided. Specifically, in southern Peru (14°-18°S), vast pediment surfaces have been abandoned through incision along the major river drainages that carve the deep canyons into the Precordillera and Western Cordillera. While the exact timing of the periods of more intense incision plausibly correspond with climate events, the total amount of incision integrated over many climate cycles is a useful indicator of tectonic activity. In this region, we find a number of geomorphic and structural features that provide strong evidence for distributed crustal deformation along range-sub-parallel contractile and strike-slip structures. Specifically, we see 1) ancient surfaces reflecting erosion rates as low as chronologies, and 6) Pleistocene mass-wasting events accommodating the redistribution of ~109-1010 m3 of material per event. Furthermore, the observation that Pleistocene incision rates are comparable with Late Miocene and Pliocene rates, suggests to us, that the rates and style of surface uplift within the forearc of southern Peru has

  17. 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...

  18. Neogene volcanism in Gutai Mts. (Eastern Carpathains: a review

    Directory of Open Access Journals (Sweden)

    Marinel Kovacs

    2003-04-01

    Full Text Available Two types of volcanism developed in Gutâi Mts. (inner volcanic chain of Eastern Carpathians: a felsic, extensional/“back-arc” type and an intermediate, arc type. The felsic volcanism of explosive origin, consisting of caldera-related rhyolitic ignimbrites and resedimented volcaniclastics, had taken place during Early-Middle Badenian and Early Sarmatian. The intermediate volcanism, consisting of extrusive (effusive and explosive and intrusive activity, had developed during Sarmatian and Pannonian (13.4-7.0 Ma. It is represented by typical calc-alkaline series, from basalts to rhyolites. Lava flows of basaltic andesites and andesites are predominant, often emplaced in subaqueous environment. Extrusive domes, mainly composed of dacites, are associated to the andesitic volcanic structures. The intermediate volcanism, consisting of extrusive (effusive and explosive and intrusive activity, had developed during Sarmatian and Pannonian (13.4-7.0 Ma. It is represented by typical calc-alkaline series, from basalts to rhyolites. Lava flows of basaltic andesites and andesites are predominant, often emplaced in subaqueous environment. Extrusive domes, mainly composed of dacites, are associated to the andesitic volcanic structures. The geochemical study on the volcanic rocks shows the calc-alkaline character of both felsic and intermediate volcanism and typical subduction zones geochemical signatures for the intermediate one. The felsic volcanism shows affinities with subduction-related rocks as well. The main petrogenetic process in Gutâi Mts. was crustal assimilation, strongly constrained by trace element and isotope geochemistry.

  19. 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

  20. Postmodern Anthropology: Reflections from Andean Ethnohistory

    Directory of Open Access Journals (Sweden)

    Villarías-Robles, Juan J. R.

    2008-06-01

    Full Text Available The postmodern perspective, which began its influence on studies of Prehispanic Peru in the 1980s, has resulted —as chief positive effect— in reflection and debate concerning the written sources for apprehending such cultural otherness, the so-called “Chronicles of the West Indies”: a perspective accompanied by new editions of these texts. The author of the present article expresses his own reflection on such change in theory and method. He argues that, with regard to self-reflectivity on its epistemological foundations, the new perspective is not entirely original in the long history of Andean ethnohistory; in effect, this approach is almost as old as the field itself. What is indeed original is the cognitive relativism that surfaced in some extreme forms of the discussion. It was an unfortunate development, however: when not denying, as a matter of principle, the very possibility of understanding that cultural otherness, arguments masked actual interpretations or explanations of its features that were protected, ipso facto, from a rigorous process of validation.

    La perspectiva posmoderna, que empezó a ser influyente en los estudios del Perú prehispánico en la década de 1980, ha tenido como principal efecto positivo la reflexión y el debate sobre las fuentes originales de conocimiento de esa alteridad cultural, las llamadas genéricamente “Crónicas de Indias”: una perspectiva acompañada de nuevas ediciones de tales textos. El autor del presente artículo hace aquí su propia reflexión sobre este cambio teórico y metodológico. Plantea que, en lo que tiene de discusión sobre sus bases epistemológicas, no es del todo original en la larga historia de la etnohistoria peruanista. Es, de hecho, casi tan antiguo como ella. Lo que sí ha sido original es el relativismo cognitivo que ha acompañado a algunas expresiones extremas de la discusión. Pero fue ésta una novedad desafortunada: cuando no negaba por principio la

  1. Interrill and rill erodibility in the northern andean highlands

    NARCIS (Netherlands)

    Romero, C.; Stroosnijder, L.; Baigorria, G.A.

    2007-01-01

    There is a lack of quantitative information describing the physical processes causing soil erosion in the Andean Highlands, especially those related to interrill and rill erodibility factors. To assess how susceptible are soils to erosion in this region, field measurements of interrill (Ki) and rill

  2. Andean shrublands of Moquegua, South Peru: Prepuna plant communities

    NARCIS (Netherlands)

    Montesinos, D.B.; Cleef, A.M.; Sykora, K.V.

    2012-01-01

    A syntaxonomic overview of shrubland vegetation in the southern Andean regions of Peru is presented. For each plant community, information is given on physiognomy, floristic diversity, ecology and geographical distribution. The shrub vegetation on the slopes of the upper Tambo river valley includes

  3. The Andean Common Market: An Experiment in Regional Cooperation.

    Science.gov (United States)

    Carlson, Reynold E.

    The Grupo Andino (GRAN) was formed in 1969 as an effort at economic integration by six Latin American countries (Bolivia, Chile, Columbia, Ecuador, Peru, and Venezuela). It was an outgrowth of its predecessor, the Latin American Free Trade Association (LAFTA), which had been formed in 1960 with eleven member countries. The Andean Group (GRAN) from…

  4. Holocene volcanic geology, volcanic hazard, and risk on Taveuni, Fiji

    International Nuclear Information System (INIS)

    Cronin, S.J.; Neall, V.E.

    2001-01-01

    The Holocene volcanic geology of Taveuni has been mapped in order to produce a volcanic hazard and risk assessment for the island. Taveuni is the third-largest island of the Fiji group and home to 14,500 people. At least cubic km 2.7 of olivine-alkali-basalt magma was erupted from over 100 events throughout the Holocene. Vents are concentrated along a northeast-striking rift zone that is parallel to other regional structural trends. There is an overall trend of younging southward along the rift. Holocene lavas and tephras are grouped within six newly defined eruptive periods, established on a basis of radiocarbon dating. Within these periods, 14 tephra layers, useful as local marker horizons, are recognised. At least 58% of Holocene eruptions produced lava flows, while almost all produced some tephra. Individual eruption event volumes ranged between 0.001 and cubic km 0.20 (dense rock equivalent). Many eruptions involved at least some phases of phreatic and/or phreato-magmatic activity, although dominant hydrovolcanic activity was limited to only a few events. A volcanic hazard map is presented, based on the Holocene geology map and statistical analyses of eruption recurrence. The highest levels of ground-based and near-vent hazards are concentrated along the southern portion of the island's rift axis, with the paths of initial lava flows predicted from present topography. Tephra fall hazards are based on eruption parameters interpreted from mapped Holocene tephra layers. Hawaiian explosive-style eruptions appear to be a dominant eruptive process, with prevailing low-level (<3 km) southeasterly winds dispersing most tephra to the northwestern quadrant. Vulnerable elements (population centres, infrastructure, and economy) on Taveuni have been considered in deriving a volcanic risk assessment for the island. A number of infrastructural and subdivision developments are either under way or planned for the island, driven by its highly fertile soils and availability of

  5. Volcanic deformation in the Andes

    Science.gov (United States)

    Riddick, S.; Fournier, T.; Pritchard, M.

    2009-05-01

    We present the results from an InSAR survey of volcanic activity in South America. We use data from the Japanese Space Agency's ALOS L-band radar satellite from 2006-2009. The L-band instrument provides better coherence in densely vegetated regions, compared to the shorter wave length C-band data. The survey reveals volcano related deformation in regions, north, central and southern, of the Andes volcanic arc. Since observations are limited to the austral summer, comprehensive coverage of all volcanoes is not possible. Yet, our combined observations reveal volcanic/hydrothermal deformation at Lonquimay, Llaima, Laguna del Maule, and Chaitén volcanoes, extend deformation measurements at Copahue, and illustrate temporal complexity to the previously described deformation at Cerro Hudson and Cordón Caulle. No precursory deformation is apparent before the large Chaitén eruption (VEI_5) of 2 May 2008, (at least before 16 April) suggesting rapid magma movement from depth at this long dormant volcano. Subsidence at Ticsani Volcano occurred coincident with an earthquake swarm in the same region.

  6. Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

    Science.gov (United States)

    Nordstrom, D. Kirk; Guo, Qinghai; McCleskey, R. Blaine

    2014-01-01

    Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1–2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.

  7. Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

    Science.gov (United States)

    Guo, Qinghai; Kirk Nordstrom, D.; Blaine McCleskey, R.

    2014-11-01

    Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1-2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.

  8. Volcanic hazards of the Idaho National Engineering Laboratory and adjacent areas

    International Nuclear Information System (INIS)

    Hackett, W.R.; Smith, R.P.

    1994-12-01

    Potential volcanic hazards are assessed, and hazard zone maps are developed for the Idaho National Engineering Laboratory (INEL) and adjacent areas. The basis of the hazards assessment and mapping is the past volcanic history of the INEL region, and the apparent similarity of INEL volcanism with equivalent, well-studied phenomena in other regions of active volcanism, particularly Hawaii and Iceland. The most significant hazards to INEL facilities are associated with basaltic volcanism, chiefly lava flows, which move slowly and mainly threaten property by inundation or burning. Related hazards are volcanic gases and tephra, and ground disturbance associated with the ascent of magma under the volcanic zones. Several volcanic zones are identified in the INEL area. These zones contain most of the volcanic vents and fissures of the region and are inferred to be the most probable sites of future INEL volcanism. Volcanic-recurrence estimates are given for each of the volcanic zones based on geochronology of the lavas, together with the results of field and petrographic investigations concerning the cogenetic relationships of INEL volcanic deposits and associated magma intrusion. Annual probabilities of basaltic volcanism within the INEL volcanic zones range from 6.2 x 10 -5 per year (average 16,000-year interval between eruptions) for the axial volcanic zone near the southern INEL boundary and the Arco volcanic-rift zone near the western INEL boundary, to 1 x 10 -5 per year (average 100,000-year interval between eruptions) for the Howe-East Butte volcanic rift zone, a geologically old and poorly defined feature of the central portion of INEL. Three volcanic hazard zone maps are developed for the INEL area: lava flow hazard zones, a tephra (volcanic ash) and gas hazard zone, and a ground-deformation hazard zone. The maps are useful in land-use planning, site selection, and safety analysis

  9. Paired Magmatic-Metallogenic Belts in Myanmar - an Andean Analogue?

    Science.gov (United States)

    Gardiner, Nicholas; Robb, Laurence; Searle, Michael; Morley, Christopher

    2015-04-01

    contrasting minerals endowment. The Mogok-Mandalay-Mergui (MMM) Belt hosts crustal-melt S-type granites with significant tin-tungsten mineralization, and contains the historically major tungsten deposit of Mawchi. The Wuntho-Popa Arc comprises I-type granites and granodiorites with porphyry-type copper-gold and epithermal gold mineralization, and includes the world-class Monywa copper mine. Recent U-Pb radiometric age dating has shown the potential for the two belts to be both active from the Late Cretaceous to Eocene. The spatial juxtaposition of these two sub-parallel belts, the implication of contemporary magmatism, and their distinct but consistent metallogenic endowment bears strong similarities to the metallogenic belts of the South American Cordillera. Here we investigate whether they together represent the magmatic and metallogenic expression of an Andean-type setting in Myanmar during the subduction of Neo-Tethys. In this analogue the Wuntho-Popa Arc represents a proximal I-type magmatic belt sited immediately above the eastwards-verging Neo-Tethys subduction zone. Exhibiting porphyry-type copper-gold and epithermal gold mineralization, this would therefore be the Myanmar equivalent of the Andean coastal copper belts. Conversely, the parallel MMM Belt, comprised of more distal crustal-melt S-type tin granites, would have an analogue in the Bolivian tin belt.

  10. Volcanic impediments in the progressive development of pre-Columbian civilizations in the Ecuadorian Andes

    Science.gov (United States)

    Hall, Minard L.; Mothes, Patricia A.

    2008-10-01

    Archaeological investigations in Ecuador have proposed that there appear to be hiatus or anomalous jumps in the progressive development of pre-Columbian indigenous cultures, based upon the fact that their ceramics and tools demonstrate abrupt advances in their sophistication at several horizons in the soil profile. Because some of these horizons are clearly associated with volcanic ash layers, archaeologists have sought a causal relation with volcanism, that is, the eruptive events or their products severely interfered with the early inhabitants, resulting in their abandonment of certain areas. Geological studies of the young volcanoes in the Ecuadorian Andes carried out during the past two decades now allow us to make a more thorough evaluation of the role of volcanism during the Holocene. This contribution briefly describes the principal Holocene volcanic events and the distribution of the corresponding eruptive products found along the InterAndean Valley, from southern Colombia to central Ecuador. Only those events that were sufficiently large that they could have had a detrimental effect on the valley's early residents are discussed. Dacitic and rhyolitic ash flows, as well as numerous debris flows (lahars) have occurred frequently and their deposits cover many valleys and floodplains, where early inhabitants probably settled. The enormous Chillos Valley lahar, associated with the 4500 yBP eruption of Cotopaxi volcano, buried soils containing ceramics of the early Formative Period. However, the greatest impact upon mankind was probably not these short-lived violent events, but rather the burying of settlements and agricultural fields by ash fallout, the effect of which may have lasted hundreds of years. Ash fall layers are observed in pre-Columbian cultural horizons in the soil profile, occurring in the InterAndean Valley, the lower flanks of the Andes, and along Ecuador's Pacific coast, the oldest corresponding to the 5800 yBP eruption of Cotopaxi. This brief

  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. A new method for monitoring global volcanic activity. [Alaska, Hawaii, Washington, California, Iceland, Guatemala, El Salvador, and Nicaragua

    Science.gov (United States)

    Ward, P. L.; Endo, E.; Harlow, D. H.; Allen, R.; Eaton, J. P.

    1974-01-01

    The ERTS Data Collection System makes it feasible for the first time to monitor the level of activity at widely separated volcanoes and to relay these data rapidly to one central office for analysis. While prediction of specific eruptions is still an evasive goal, early warning of a reawakening of quiescent volcanoes is now a distinct possibility. A prototypical global volcano surveillance system was established under the ERTS program. Instruments were installed in cooperation with local scientists on 15 volcanoes in Alaska, Hawaii, Washington, California, Iceland, Guatemala, El Salvador and Nicaragua. The sensors include 19 seismic event counters that count four different sizes of earthquakes and six biaxial borehole tiltmeters that measure ground tilt with a resolution of 1 microradian. Only seismic and tilt data are collected because these have been shown in the past to indicate most reliably the level of volcano activity at many different volcanoes. Furthermore, these parameters can be measured relatively easily with new instrumentation.

  13. Basaltic volcanic episodes of the Yucca Mountain region

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1990-01-01

    The purpose of this paper is to summarize briefly the distribution and geologic characteristics of basaltic volcanism in the Yucca Mountain region during the last 10--12 Ma. This interval largely postdates the major period of silicic volcanism and coincides with and postdates the timing of major extensional faulting in the region. Field and geochronologic data for the basaltic rocks define two distinct episodes. The patterns in the volume and spatial distribution of these basaltic volcanic episodes in the central and southern part of the SNVF are used as a basis for forecasting potential future volcanic activity in vicinity of Yucca Mountain. 33 refs., 2 figs

  14. 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.

  15. Volcanic Supersites as cross-disciplinary laboratories

    Science.gov (United States)

    Provenzale, Antonello; Beierkuhnlein, Carl; Giamberini, Mariasilvia; Pennisi, Maddalena; Puglisi, Giuseppe

    2017-04-01

    Volcanic Supersites, defined in the frame of the GEO-GSNL Initiative, are usually considered mainly for their geohazard and geological characteristics. However, volcanoes are extremely challenging areas from many other points of view, including environmental and climatic properties, ecosystems, hydrology, soil properties and biogeochemical cycling. Possibly, volcanoes are closer to early Earth conditions than most other types of environment. During FP7, EC effectively fostered the implementation of the European volcano Supersites (Mt. Etna, Campi Flegrei/Vesuvius and Iceland) through the MED-SUV and FUTUREVOLC projects. Currently, the large H2020 project ECOPOTENTIAL (2015-2019, 47 partners, http://www.ecopotential-project.eu/) contributes to GEO/GEOSS and to the GEO ECO Initiative, and it is devoted to making best use of remote sensing and in situ data to improve future ecosystem benefits, focusing on a network of Protected Areas of international relevance. In ECOPOTENTIAL, remote sensing and in situ data are collected, processed and used for a better understanding of the ecosystem dynamics, analysing and modelling the effects of global changes on ecosystem functions and services, over an array of different ecosystem types, including mountain, marine, coastal, arid and semi-arid ecosystems, and also areas of volcanic origin such as the Canary and La Reunion Islands. Here, we propose to extend the network of the ECOPOTENTIAL project to include active Volcanic Supersites, such as Mount Etna and other volcanic Protected Areas, and we discuss how they can be included in the framework of the ECOPOTENTIAL workflow. A coordinated and cross-disciplinary set of studies at these sites should include geological, biological, ecological, biogeochemical, climatic and biogeographical aspects, as well as their relationship with the antropogenic impact on the environment, and aim at the global analysis of the volcanic Earth Critical Zone - namely, the upper layer of the Earth

  16. Composition and diversity of High Andean in the Fauna Production Reserve Chimborazo, Ecuador

    Directory of Open Access Journals (Sweden)

    Jorge Caranqui

    2016-03-01

    Full Text Available The present study inquire the floristic diversity of 9 sampling in four plots of 1 m² of high andean in several locations in the “Reserva de Producción de Fauna Chimborazo”. For the development of this study, we used an adaptation of the method of plots “Gloria”. With coverage (% in each of the plots, Further the diversity indices and similarity with respective analysis were obtained. The data obtained reflect a diversity that can range from medium to low, believe that this is due to anthropogenic activities that have taken place in these ecosistems. With the presence mostly Calamagrostis intermedia, it could establish that the type of vegetation is herbaceous in high andean is higher percentage; is the species that is almost always present in most types of vegetation of the RPF Chimborazo and high dominance that influences the results of low floristic diversity indices was found in the analysis. As a result the most abundant family Asteraceae is well Poaceae.

  17. Venus - Volcanic features in Atla Region

    Science.gov (United States)

    1991-01-01

    This Magellan image from the Atla region of Venus shows several types of volcanic features and superimposed surface fractures. The area in the image is approximately 350 kilometers (217 miles) across, centered at 9 degrees south latitude, 199 degrees east longitude. Lava flows emanating from circular pits or linear fissures form flower-shaped patterns in several areas. A collapse depression approximately 20 kilometers by 10 kilometers (12 by 6 miles) near the center of the image is drained by a lava channel approximately 40 kilometers (25 miles) long. Numerous surface fractures and graben (linear valleys) criss-cross the volcanic deposits in north to northeast trends. The fractures are not buried by the lavas, indicating that the tectonic activity post-dates most of the volcanic activity.

  18. Developing International Guidelines on Volcanic Hazard Assessments for Nuclear Facilities

    Science.gov (United States)

    Connor, Charles

    2014-05-01

    Worldwide, tremendous progress has been made in recent decades in forecasting volcanic events, such as episodes of volcanic unrest, eruptions, and the potential impacts of eruptions. Generally these forecasts are divided into two categories. Short-term forecasts are prepared in response to unrest at volcanoes, rely on geophysical monitoring and related observations, and have the goal of forecasting events on timescales of hours to weeks to provide time for evacuation of people, shutdown of facilities, and implementation of related safety measures. Long-term forecasts are prepared to better understand the potential impacts of volcanism in the future and to plan for potential volcanic activity. Long-term forecasts are particularly useful to better understand and communicate the potential consequences of volcanic events for populated areas around volcanoes and for siting critical infrastructure, such as nuclear facilities. Recent work by an international team, through the auspices of the International Atomic Energy Agency, has focused on developing guidelines for long-term volcanic hazard assessments. These guidelines have now been implemented for hazard assessment for nuclear facilities in nations including Indonesia, the Philippines, Armenia, Chile, and the United States. One any time scale, all volcanic hazard assessments rely on a geologically reasonable conceptual model of volcanism. Such conceptual models are usually built upon years or decades of geological studies of specific volcanic systems, analogous systems, and development of a process-level understanding of volcanic activity. Conceptual models are used to bound potential rates of volcanic activity, potential magnitudes of eruptions, and to understand temporal and spatial trends in volcanic activity. It is these conceptual models that provide essential justification for assumptions made in statistical model development and the application of numerical models to generate quantitative forecasts. It is a

  19. Responses to, and the short and long-term impacts of, the 1957/1958 Capelinhos volcanic eruption and associated earthquake activity on Faial, Azores

    Science.gov (United States)

    Coutinho, Rui; Chester, David K.; Wallenstein, Nicolau; Duncan, Angus M.

    2010-10-01

    The 1957/58 Capelinhos eruption on Faial Island in the Azores is well known for being an excellent example of Surtseyan hydromagmatic volcanic activity. Less well known are the responses of the Portuguese authorities to the eruption and subsequent earthquake in May 1958, and the ways in which well-thought-out and generally effective recovery programmes were put in place. At the time Portugal was ruled by a dictatorship, the Estado Novo (New State). Only superficially similar to other fascist governments in Southern Europe, the Estado Novo collected huge amounts of data on the responses of the authorities to the disaster and their programmes of recovery, but never encouraged academic evaluation of policy, although it ensured that the scientific aspects of the eruption and earthquake were meticulously recorded and published. In this paper we remedy this situation by discussing the details of the immediate response to the emergency and the ways in which the island recovered in its aftermath. The study is based not only on archival sources and demographic and economic data, but also on detailed interviews with survivors some of whom were also decision makers. We argue that response, recovery and rehabilitation were generally highly successful and assess the lessons of the 1957/58 emergency which are relevant to future geophysical disasters in Faial and the wider Azores. Since the 1974 revolution Portugal has been a democratic state. We conclude that both the legislation and the civil defence infrastructure, necessary to achieve a similarly strong and successful response, are in place today.

  20. Social inequality and child malnutrition in four Andean countries

    OpenAIRE

    Carlos Larrea; Wilma Freire

    2002-01-01

    Objective. To analyze the effects of socioeconomic, regional, and ethnic conditions on chronic malnutrition in four Andean countries of South America: Bolivia, Colombia, Ecuador, and Peru. Methods. The study was based on Demographic and Health Surveys (DHS) for Colombia (1995), Peru (1996), and Bolivia (1997), and on a Living Standard Measurement Survey for Ecuador (1998). We developed an index of household socioeconomic status using categorical principal components analysis. We broke down th...

  1. Volcanism Studies: Final Report for the Yucca Mountain Project

    International Nuclear Information System (INIS)

    Crowe, Bruce M.; Perry, Frank V.; Valentine, Greg A.; Bowker, Lynn M.

    1998-01-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt ( than about 7 x 10 -8 events yr -1 . Simple probability estimates are used to assess possible implications of not drilling aeromagnetic anomalies in the Amargosa Valley. The sensitivity of the disruption probability to the location of northeast boundaries of volcanic zones near the Yucca Mountain sit

  2. 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

  3. Genetic diversity and germplasm conservation of three minor Andean tuber crop species

    Directory of Open Access Journals (Sweden)

    Malice M.

    2009-01-01

    Full Text Available In traditional Andean agrosystems, three minor tuber crop species are of regional or local importance: oca (Oxalis tuberosa Molina, ulluco (Ullucus tuberosus Caldas and mashua (Tropaeolum tuberosum Ruiz and Pav.. Genetic diversity within these species is very large and could result from the high ecological and cultural variability that characterizes the Andean area. Nowadays, many anthropic or ecological factors cause the loss of diversity and contribute to genetic erosion. The development of conservation strategies for genetic resources of Andean tubers, in situ as well as ex situ, includes a better knowledge of diversity in addition to the study of Andean farming strategies linked to this genetic diversity.

  4. Modeling volcanic ash dispersal

    CERN Multimedia

    CERN. Geneva

    2010-01-01

    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  5. Predicting Polylepis distribution: vulnerable and increasingly important Andean woodlands

    Directory of Open Access Journals (Sweden)

    Brian R. Zutta

    2012-11-01

    Full Text Available Polylepis woodlands are a vital resource for preserving biodiversity and hydrological functions, which will be altered by climate change and challenge the sustainability of local human communities. However, these highaltitude Andean ecosystems are becoming increasingly vulnerable due to anthropogenic pressure including fragmentation, deforestation and the increase in livestock. Predicting the distribution of native woodlands has become increasingly important to counteract the negative effects of climate change through reforestation and conservation. The objective of this study was to develop and analyze the distribution models of two species that form extensive woodlands along the Andes, namely Polylepis sericea and P. weberbaueri. This study utilized the program Maxent, climate and remotely sensed environmental layers at 1 km resolution. The predicted distribution model for P. sericea indicated that the species could be located in a variety of habitats along the Andean Cordillera, while P. weberbaueri was restricted to the high elevations of southern Peru and Bolivia. For both species, elevation and temperature metrics were the most significant factors for predicted distribution. Further model refinement of Polylepis and other Andean species using increasingly available satellite data demonstrate the potential to help define areas of diversity and improve conservation strategies for the Andes.

  6. 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

  7. 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

  8. Origin and evolution of geothermal fluids from Las Tres Vírgenes and Cerro Prieto fields, Mexico – Co-genetic volcanic activity and paleoclimatic constraints

    International Nuclear Information System (INIS)

    Birkle, Peter; Marín, Enrique Portugal; Pinti, Daniele L.; Castro, M. Clara

    2016-01-01

    during the final stage of the Last Glacial Pluvial period. Quaternary recharge of the LTV geothermal reservoir is related to elevated precipitation rates during cooler-humid climate intervals in the Late Pleistocene and Early Holocene. The probable replacement of connate water or pore fluids by infiltrating surface water might have been triggered by enhanced fracture and fault permeability through contemporaneous tectonic–volcanic activity in the Las Tres Vírgenes region. Fast hydrothermal alteration processes caused a secondary, positive δ 18 O-shift from 4‰ to 6‰ for LTV and from 2‰ to 4‰ for CP geothermal fluids since the Late Glacial infiltration. - Highlights: • U-Th/He ages for Cerro Prieto fluids show 4 He flux from granite basement or brines. • LTV geothermal water is composed of Quaternary meteoric water and fossil seawater. • 14 C and 4 He suggest Quaternary recharge of Las Tres Vírgenes geothermal reservoir. • Paleotemperatures point to cooler-humid climate in NW-Mexico during recharge.

  9. Nd, Sr-isotopic provenance and trace element geochemistry of Amazonian foreland basin fluvial sands, Bolivia and Peru: Implications for ensialic Andean orogeny

    International Nuclear Information System (INIS)

    Basu, A.R.; Sharma, M.; DeCelles, P.G.

    1990-01-01

    Nd and Sr isotopes and the trace element contents, including the rare earths, were determined for fluvial sands of lithic arenite composition from the Madre de Dios foreland basin of Bolivia and Peru. On standard petrologic ternary diagrams, the sands fall in the recycled orogen provenance field and thus are similar to typical ancient foreland basin composition. The average rare earth elemental pattern of the sands is identical to the upper continental crustal average, as estimated from post-Archean composite shales of different continents. Ratio of Th/U, Co/Th, La/Sc and Th/Sc of the fluvial sands are intermediate between an average magmatic arc and an upper crustal average compositions. The dispersion of some trace elemental patterns in the sands can be attributed to fractionation of dense minerals, including zircon, during the sedimentation process. The variations of Nd isotopes in conjunction with the petrographic parameters of lithic metamorphic (Lm) and volcanic (Lv) fragments allow a two-fold classification of the sands. These two sand types can be interpreted in terms of mixing among three different provenances: one volcanic rock-suit with less negative ε Nd (O) parameter than the other volcanic suite, and a third metasedimentary source with ε Nd (O) value of around -12, which is considered to be similar to the average western Brazilian shield composition. Thus the overall compositions of the sands has been modeled as mechanical mixtures of two components, an Andean magmatic arc and the Brazilian shield-derived metasediments. The model is strongly supported by a plot of ε Nd (O) versus ε Sr (O) of the sands. In this plot, the Type 1 and 2 sands define two coherent hyperbolic trends contiguous with two different portions of the Andean magmatic trend. (orig./WB)

  10. Volcanic Eruptions in Kamchatka

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Sheveluch Stratovolcano Click on the image for full resolution TIFF Klyuchevskoy Stratovolcano Click on the image for full resolution TIFF One of the most volcanically active regions of the world is the Kamchatka Peninsula in eastern Siberia, Russia. It is not uncommon for several volcanoes to be erupting at the same time. On April 26, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radioneter (ASTER) on NASA's Terra spacecraft captured these images of the Klyuchevskoy and Sheveluch stratovolcanoes, erupting simultaneously, and 80 kilometers (50 miles) apart. Over Klyuchevskoy, the thermal infrared data (overlaid in red) indicates that two open-channel lava flows are descending the northwest flank of the volcano. Also visible is an ash-and-water plume extending to the east. Sheveluch volcano is partially cloud-covered. The hot flows highlighted in red come from a lava dome at the summit. They are avalanches of material from the dome, and pyroclastic flows. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra spacecraft. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and

  11. Volcanic hazards and public response

    Science.gov (United States)

    Peterson, Donald W.

    1988-05-01

    Although scientific understanding of volcanoes is advancing, eruptions continue to take a substantial toll of life and property. Some of these losses could be reduced by better advance preparation, more effective flow of information between scientists and public officials, and better understanding of volcanic behavior by all segments of the public. The greatest losses generally occur at volcanoes that erupt infrequently where people are not accustomed to dealing with them. Scientists sometimes tend to feel that the blame for poor decisions in emergency management lies chiefly with officials or journalists because of their failure to understand the threat. However, the underlying problem embraces a set of more complex issues comprising three pervasive factors. The first factor is the volcano: signals given by restless volcanoes are often ambiguous and difficult to interpret, especially at long-quiescent volcanoes. The second factor is people: people confront hazardous volcanoes in widely divergent ways, and many have difficulty in dealing with the uncertainties inherent in volcanic unrest. The third factor is the scientists: volcanologists correctly place their highest priority on monitoring and hazard assessment, but they sometimes fail to explain clearly their conclusions to responsible officials and the public, which may lead to inadequate public response. Of all groups in society, volcanologists have the clearest understanding of the hazards and vagaries of volcanic activity; they thereby assume an ethical obligation to convey effectively their knowledge to benefit all of society. If society resists, their obligation nevertheless remains. They must use the same ingenuity and creativity in dealing with information for the public that they use in solving scientific problems. When this falls short, even excellent scientific results may be nullified.

  12. Andean cutaneous leishmaniasis (Andean-CL, uta) in Peru and Ecuador: the causative Leishmania parasites and clinico-epidemiological features.

    Science.gov (United States)

    Hashiguchi, Yoshihisa; Gomez, Eduardo A L; Cáceres, Abraham G; Velez, Lenin N; Villegas, Nancy V; Hashiguchi, Kazue; Mimori, Tatsuyuki; Uezato, Hiroshi; Kato, Hirotomo

    2018-01-01

    This study provides comprehensive information on the past and current status of the Andean cutaneous leishmaniasis (Andean-CL, uta) in Peru and Ecuador, mainly focusing on the causative Leishmania parasites and clinico-epidemiological features. Available information and data including our unpublished works were analyzed thoroughly. Endemic regions of the Andean-CL (uta) in Peru run from the north Piura/Cajamarca to the south Ayacucho at a wide range of the Pacific watersheds of the Andes through several departments, while in Ecuador those exist at limited and spotted areas in the country's mid-southwestern two provinces, Azuay and Chimborazo. The principal species of the genus Leishmania are completely different at subgenus level, L. (Viannia) peruviana in Peru, and L. (Leishmania) mexicana and L. (L.) major-like (infrequent occurrence) in Ecuador. The Peruvian uta is now prevalent in different age and sex groups, being not clearly defined as found in the past. The precise reasons are not known and should be elucidated further, though probable factors, such as emergence of other Leishmania parasites, non-immune peoples' migration into the areas, etc., were discussed briefly in the text. The Andean-CL cases in Ecuador are more rural than before, probably because of a rapid development of the Leishmania-positive communities and towns, and the change of life-styles of the inhabitants, including newly constructed houses and roads in the endemic areas. Such information is helpful for future management of the disease, not only for Leishmania-endemic areas in the Andes but also for other endemic areas. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development

    Science.gov (United States)

    Korteniemi, J.; Kukkonen, S.

    2018-04-01

    Outflow channel formation on the eastern Hellas rim region is traditionally thought to have been triggered by activity phases of the nearby volcanoes Hadriacus and Tyrrhenus Montes: As a result of volcanic heating subsurface volatiles were mobilized. It is, however, under debate, whether eastern Hellas volcanism was in fact more extensive, and if there were volcanic centers separate from the identified central volcanoes. This work describes previously unrecognized structures in the Niger-Dao Valles outflow channel complex. We interpret them as volcanic edifices: cones, a shield, and a caldera. The structures provide evidence of an additional volcanic center within the valles and indicate volcanic activity both prior to and following the formation of the outflow events. They expand the extent, type, and duration of volcanic activity in the Circum-Hellas Volcanic Province and provide new information on interaction between volcanism and fluvial activity.

  14. Opening of the Gulf of Guayaquil: quantifying the motion from the trench to the Andean Cordillera

    Science.gov (United States)

    Santana, E.; Dumont, J. F.; Vilema, W.; Pedoja, K.

    2003-04-01

    The Gulf of Guayaquil is a complex pull-apart opened at the south tip of the North Andean Block. The Guayaquil-Caracas Megashear (i.e. Dolores-Guayaquil Megashear) which bounds the North Andean Block to the east crosses the Western Andean Cordillera along the Pallatanga fault, and joins southwestward the Ecuadorian trench. According to paleogeographic data the Gulf of Guayaquil began to open about 9 Ma ago, which is evidenced now by about 100 km offset of the Early Neogene Progresso and Loja basins. A lesser post orogenic offset of about 60 km is observed along the Pallatanga fault, coherent with the offset of the piedmont of the Western Andean Cordillera. The discrepancy suggests a partition of the deformation at the south tip of the North Andean Block, part of the motion being accommodated by other small faults north of the Pallatanga fault zone and resulting in a pull apart motion and subsidence of the Daule-Babahoyo basin. The main curve of the Tallara Arc described by the trend of the trench from north Peru to north Ecuador shows a significant anomaly in front of the Gulf of Guayaquil. A 60 to 70 km minimum right hand deviation of the curve is observed, displayed in three segments delimited by faults. Neotectonic studies in the Santa Clara and Puná Islands located in the Gulf of Guayaquil show a regional E-W shortening during the Pleistocene, characterised by right lateral motion along the Zambapala Cordillera in Puná. Offset of river drainage and morphostructures in South Puná gives evidence of 3 km dextral offset which post-date marine terraces with an estimated age of M.I.S. 9 or 11, giving mean offset rates of 9 mm/y or 6.8 mm/y respectively. The conclusion underlines the following points: (1) These data suggest that the offset rate inside the Gulf of Guayaquil during the Late Quaternary is lower than the mean rate observed since 9 Ma. The apparent slow down may be due to the partition of the deformation of the Gulf of Guayaquil towards the Guayas

  15. Conceptual model of volcanism and volcanic hazards of the region of Ararat valley, Armenia

    Science.gov (United States)

    Meliksetian, Khachatur; Connor, Charles; Savov, Ivan; Connor, Laura; Navasardyan, Gevorg; Manucharyan, Davit; Ghukasyan, Yura; Gevorgyan, Hripsime

    2015-04-01

    Armenia and the adjacent volcanically active regions in Iran, Turkey and Georgia are located in the collision zone between the Arabian and Eurasian lithospheric plates. The majority of studies of regional collision related volcanism use the model proposed by Keskin, (2003) where volcanism is driven by Neo-Tethyan slab break-off. In Armenia, >500 Quaternary-Holocene volcanoes from the Gegham, Vardenis and Syunik volcanic fields are hosted within pull-apart structures formed by active faults and their segments (Karakhanyan et al., 2002), while tectonic position of the large in volume basalt-dacite Aragats volcano and periphery volcanic plateaus is different and its position away from major fault lines necessitates more complex volcano-tectonic setup. Our detailed volcanological, petrological and geochemical studies provide insight into the nature of such volcanic activity in the region of Ararat Valley. Most magmas, such as those erupted in Armenia are volatile-poor and erupt fairly hot. Here we report newly discovered tephra sequences in Ararat valley, that were erupted from historically active Ararat stratovolcano and provide evidence for explosive eruption of young, mid K2O calc-alkaline and volatile-rich (>4.6 wt% H2O; amph-bearing) magmas. Such young eruptions, in addition to the ignimbrite and lava flow hazards from Gegham and Aragats, present a threat to the >1.4 million people (~ ½ of the population of Armenia). We will report numerical simulations of potential volcanic hazards for the region of Ararat valley near Yerevan that will include including tephra fallout, lava flows and opening of new vents. Connor et al. (2012) J. Applied Volcanology 1:3, 1-19; Karakhanian et al. (2002), JVGR, 113, 319-344; Keskin, M. (2003) Geophys. Res. Lett. 30, 24, 8046.

  16. Some isotopic and geochemical anomalies observed in Mexico prior to large scale earthquakes and volcanic eruptions

    International Nuclear Information System (INIS)

    Cruz R, S. de la; Armienta, M.A.; Segovia A, N.

    1992-05-01

    A brief account of some experiences obtained in Mexico, related with the identification of geochemical precursors of volcanic eruptions and isotopic precursors of earthquakes and volcanic activity is given. The cases of three recent events of volcanic activity and one large earthquake are discussed in the context of an active geological environment. The positive results in the identification of some geochemical precursors that helped to evaluate the eruptive potential during two volcanic crises (Tacana 1986 and Colima 1991), and the significant radon-in-soil anomalies observed during a volcanic catastrophic eruption (El Chichon, 1982) and prior to a major earthquake (Michoacan, 1985) are critically analysed. (Author)

  17. Some isotopic and geochemical anomalies observed in Mexico prior to large scale earthquakes and volcanic eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Cruz R, S. de la; Armienta, M A; Segovia A, N

    1992-05-15

    A brief account of some experiences obtained in Mexico, related with the identification of geochemical precursors of volcanic eruptions and isotopic precursors of earthquakes and volcanic activity is given. The cases of three recent events of volcanic activity and one large earthquake are discussed in the context of an active geological environment. The positive results in the identification of some geochemical precursors that helped to evaluate the eruptive potential during two volcanic crises (Tacana 1986 and Colima 1991), and the significant radon-in-soil anomalies observed during a volcanic catastrophic eruption (El Chichon, 1982) and prior to a major earthquake (Michoacan, 1985) are critically analysed. (Author)

  18. Lidar Observations of Aerosol Disturbances of the Stratosphere over Tomsk (56.5∘N; 85.0∘E in Volcanic Activity Period 2006–2011

    Directory of Open Access Journals (Sweden)

    Oleg E. Bazhenov

    2012-01-01

    Full Text Available The lidar measurements (Tomsk: 56.5∘N; 85.0∘E of the optical characteristics of the stratospheric aerosol layer (SAL in the volcanic activity period 2006–2011 are summarized and analyzed. The background SAL state with minimum aerosol content, observed since 1997 under the conditions of long-term volcanically quiet period, was interrupted in October 2006 by series of explosive eruptions of volcanoes of Pacific Ring of Fire: Rabaul (October 2006, New Guinea; Okmok and Kasatochi (July-August 2008, Aleutian Islands; Redoubt (March-April 2009, Alaska; Sarychev Peak (June 2009, Kuril Islands; Grimsvötn (May 2011, Iceland. A short-term and minor disturbance of the lower stratosphere was also observed in April 2010 after eruption of the Icelandic volcano Eyjafjallajokull. The developed regional empirical model of the vertical distribution of background SAL optical characteristics was used to identify the periods of elevated stratospheric aerosol content after each of the volcanic eruptions. Trends of variations in the total ozone content are also considered.

  19. Amazonian volcanism inside Valles Marineris on Mars

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Hauber, E.; Wray, J. J.; Michael, G.

    2017-01-01

    Roč. 473, September (2017), s. 122-130 ISSN 0012-821X Institutional support: RVO:67985530 Keywords : Mars * Valles Marineris * volcanism * scoria cone * hydrothermal activity Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Volcanology Impact factor: 4.409, year: 2016

  20. Andean contributions to the biogeochemistry of the amazon river system

    Directory of Open Access Journals (Sweden)

    1995-01-01

    Atlántico. Un nuevo programa colaborativo de investigación se inició en 1994 con el propósito de caracterizar de una manera más completa la biogeoquímica de los ríos andinos. Contributions from Andean rivers may play a significant role in determining the basin-wide biogeochemistry integrated into the mainstem Amazon River of Brazil. Concentration data for organic C, NO3-, and PO43- in Andean rivers are highly variable and reveal no clear spatial or altitudinal patterns. Concentrations measured in Andean rivers are similar to those reported in the mainstem Amazon river and its major tributaries. Explanations of processes which alter Andean-derived particulates and solutes as they exit the Cordillera are only speculative at this time, but their net effect is to diminish Andean signals through decomposition and dilution by lowland inputs. The 13C of particulate and dissolved organic matter in the mainstem Amazon provides evidence that some fraction of Andean derived material persists within the river system, ultimately to be discharged to the Atlantic Ocean. In 1994 a new collaborative research program was launched to further characterize the biogeochemistry of Andean rivers.

  1. Geochemistry and Geochronology of Ngorongoro Crater, Tanzania: Implication for Magma Evolution, Duration of Volcanic Activity and Age of the Ngorongoro N-R Geomagnetic Polarity Transition

    Science.gov (United States)

    Mollel, G. F.; Swisher, C. C.; Feigenson, M. D.; Carr, M. J.

    2005-05-01

    40Ar/39Ar dates on volcanic rocks from the Ngorongoro Crater (NC) in northern Tanzania indicate that NC activity was very short in duration lasting approximately 120 ka. Laser incremental heating experiments on lava from the bottom and top of the NC crater-wall section gave ages of 2.08 +/- 0.04 and 1.96 +/- 0.02 Ma respectively. Lavas from the same section show a change in magnetic polarity from normal (N) at the lower part to reverse (R) polarity at the upper part (Grommé et al. 1970). The new ages are about 400 ka younger than previously estimated by K-Ar technique. These new ages suggest correlation of the NC N-R polarity transition to the 2.1 Ma (N-R) Reunion-Matuyama boundary (Cande and Kent, 1995), instead of the Gauss-Matuyama boundary as proposed by Grommé et al. (1970). 87Sr/86Sr measurements on lavas from the NC section vary widely from 0.70801 in the trachydacite at the base to 0.70405 in the basaltic lava near the top. The lower part of the section is more radiogenic varying from 0.70592 to 0.70801 whereas the upper part is constrained to 0.70405 to 0.70450. The more radiogenic lower part is likely to have interacted with crustal rocks. Two possible contaminants are the Tanzanian Archean Craton to the west and the late Proterozoic Mozambican belt in the east. The crater-wall section is composed of trachydacite at the bottom that becomes trachyandesite in mid-section. The top section is mainly basaltic. Major and trace elements show an inverted geochemical signature that is typical of stratified magma chambers characterized by a silicic top and basaltic bottom. Olivine basalt at the upper part of the section has the highest Mg# (56.60) and in general the upper section is more mafic than the lower section as inferred from Mg#. The upper part of the section is high in TiO2, MgO, FeOT, and CaO wt% whereas SiO2 and K2O wt% are higher in lower part of the section. No significant variations are observed in N2O, Al2O3, P2O5 and MnO wt% up-section. Highly

  2. Screening criteria of volcanic hazards aspect in the NPP site evaluation

    International Nuclear Information System (INIS)

    Nur Siwhan

    2013-01-01

    Studies have been conducted on the completeness of regulation in Indonesia particularly on volcanic hazards aspects in the evaluation of nuclear power plant site. Volcanic hazard aspect needed to identify potential external hazards that may endanger the safety of the operation of nuclear power plants. There are four stages for evaluating volcanic hazards, which are initial assessment, characterization sources of volcanic activity in the future, screening volcanic hazards and assessment of capable volcanic hazards. This paper discuss the third stage of the general evaluation which is the screening procedure of volcanic hazards. BAPETEN Chairman Regulation No. 2 Year of 2008 has only one screening criteria for missile volcanic phenomena, so it required screening criteria for other hazard phenomena that are pyroclastic flow density; lava flows; avalanche debris materials; lava; opening hole new eruptions, volcano missile; tsunamis; ground deformation; and hydrothermal system and ground water anomaly. (author)

  3. 238U-230Th-226Ra systematics applied to the active oceanic volcanism. Constraints on the duration and processes of magmas formation

    International Nuclear Information System (INIS)

    Claude-Ivana, Ch.

    1997-02-01

    The development of a new precise analytical technique for measuring radioactive disequilibria by TIMS has enabled to put constraints on both the extend and time scale of incompatible element fractionation during magma formation in oceanic islands. Three different settings have been studied: the Grande Comore volcanoes (Comores archipelago), Tenerife and Lanzarote volcanism (Canary islands) and four islands within the Azores: Sao Miguel, Terceira, Pico and Faial islands. The Comores and Canaries archipelagoes are both lying on an old thick oceanic lithosphere. The detailed case in Grande Comore shows evidence for a process of interaction of the Comore plume with the underlying lithosphere. In the Canaries, the lithosphere also contributes to lava formation either during the differentiation (in Tenerife) or during mantle melting (in Lanzarote). Within the Azores, U-series measurements reveal large geochemical and isotopic variations between the different islands that we interpret as reflecting heterogeneities in the Azore plume. In particular, the U-Th fractionation in Sao Miguel volcanics is though to result from melting of an hydrous sediment-bearing mantle. The magma transit times have been found to be very short (1000 yr) in all the basaltic series. This very rapid migration of the melts is an evidence for the absence of large magma chamber and for processes of fracturing during melt transports. However, this model does not apply in the case of the very evolved volcanic series in Tenerife island (Canaries) where transit times of c.a. 100000 yr indicate the presence of a large magmatic reservoir. (author)

  4. Assessment of the atmospheric impact of volcanic eruptions

    Science.gov (United States)

    Sigurdsson, H.

    1988-01-01

    The dominant global impact of volcanic activity is likely to be related to the effects of volcanic gases on the Earth's atmosphere. Volcanic gas emissions from individual volcanic arc eruptions are likely to cause increases in the stratospheric optical depth that result in surface landmass temperature decline of 2 to 3 K for less than a decade. Trachytic and intermediate magmas are much more effective in this regard than high-silica magmas, and may also lead to extensive ozone depletion due to effect of halogens and magmatic water. Given the assumed relationship between arc volcanism and subduction rate, and the relatively small variation in global spreading rates in the geologic record, it is unlikely that the rates of arc volcanism have varied greatly during the Cenozoic. Hotspot related basaltic fissure eruptions in the subaerial environment have a higher mass yield of sulfur, but lofting of the valcanic aerosol to levels above the tropopause is required for a climate impact. High-latitude events, such as the Laki 1783 eruption can easily penetrate the tropopause and enter the stratosphere, but formation of a stratospheric volcanic aerosol form low-latitude effusive basaltic eruptions is problematical, due to the elevated low-latitude tropopause. Due to the high sulfur content of hotspot-derived basaltic magmas, their very high mass eruption rates and the episodic behavior, hotspots must be regarded as potentially major modifiers of Earth's climate through the action of their volcanic volatiles on the chemistry and physics of the atmosphere.

  5. Assessment of volcanic hazards, vulnerability, risk and uncertainty (Invited)

    Science.gov (United States)

    Sparks, R. S.

    2009-12-01

    A volcanic hazard is any phenomenon that threatens communities . These hazards include volcanic events like pyroclastic flows, explosions, ash fall and lavas, and secondary effects such as lahars and landslides. Volcanic hazards are described by the physical characteristics of the phenomena, by the assessment of the areas that they are likely to affect and by the magnitude-dependent return period of events. Volcanic hazard maps are generated by mapping past volcanic events and by modelling the hazardous processes. Both these methods have their strengths and limitations and a robust map should use both approaches in combination. Past records, studied through stratigraphy, the distribution of deposits and age dating, are typically incomplete and may be biased. Very significant volcanic hazards, such as surge clouds and volcanic blasts, are not well-preserved in the geological record for example. Models of volcanic processes are very useful to help identify hazardous areas that do not have any geological evidence. They are, however, limited by simplifications and incomplete understanding of the physics. Many practical volcanic hazards mapping tools are also very empirical. Hazards maps are typically abstracted into hazards zones maps, which are some times called threat or risk maps. Their aim is to identify areas at high levels of threat and the boundaries between zones may take account of other factors such as roads, escape routes during evacuation, infrastructure. These boundaries may change with time due to new knowledge on the hazards or changes in volcanic activity levels. Alternatively they may remain static but implications of the zones may change as volcanic activity changes. Zone maps are used for planning purposes and for management of volcanic crises. Volcanic hazards maps are depictions of the likelihood of future volcanic phenomena affecting places and people. Volcanic phenomena are naturally variable, often complex and not fully understood. There are

  6. National volcanic ash operations plan for aviation

    Science.gov (United States)

    ,; ,

    2007-01-01

    International Civil Aviation Organization’s (ICAO) International Airways Volcano Watch. This plan defines agency responsibilities, provides a comprehensive description of an interagency standard for volcanic ash products and their formats, describes the agency backup procedures for operational products, and outlines the actions to be taken by each agency following an occurrence of a volcanic eruption that subsequently affects and impacts aviation services. Since our most recent International Conference on Volcanic Ash and Aviation Safety, volcanic ash-related product and service activities have grown considerably along with partnerships and alliances throughout the aviation community. In January 2005, the National Oceanic and Atmospheric Administration’s National Centers for Environment Prediction began running the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model in place of the Volcanic Ash Forecast Transport and Dispersion (VAFTAD) model, upgrading support to the volcanic ash advisory community. Today, improvements to the HYSPLIT model are ongoing based on recommendations by the OFCM-sponsored Joint Action Group for the Selection and Evaluation of Atmospheric Transport and Diffusion Models and the Joint Action Group for Atmospheric Transport and Diffusion Modeling (Research and Development Plan). Two international workshops on volcanic ash have already taken place, noticeable improvements and innovations in education, training, and outreach have been made, and federal and public education and training programs on volcanic ash-related products, services, and procedures iv continue to evolve. For example, in partnership with Embry-Riddle Aeronautical University and other academic institutions, volcanic ash hazard and mitigation training has been incorporated into aviation meteorology courses. As an essential next step, our volcanic ash-related efforts in the near term will be centered on the development of an interagency implementation plan to

  7. Cenozoic intraplate tectonics in Central Patagonia: Record of main Andean phases in a weak upper plate

    Science.gov (United States)

    Gianni, G. M.; Echaurren, A.; Folguera, A.; Likerman, J.; Encinas, A.; García, H. P. A.; Dal Molin, C.; Valencia, V. A.

    2017-11-01

    Contraction in intraplate areas is still poorly understood relative to similar deformation at plate margins. In order to contribute to its comprehension, we study the Patagonian broken foreland (PBF) in South America whose evolution remains controversial. Time constraints of tectonic events and structural characterization of this belt are limited. Also, major causes of strain location in this orogen far from the plate margin are enigmatic. To unravel tectonic events, we studied the Cenozoic sedimentary record of the central sector of the Patagonian broken foreland (San Bernardo fold and thrust belt, 44°30‧S-46°S) and the Andes (Meseta de Chalia, 46°S) following an approach involving growth-strata detection, U-Pb geochronology and structural modeling. Additionally, we elaborate a high resolution analysis of the effective elastic thickness (Te) to examine the relation between intraplate contraction location and variations in lithospheric strength. The occurrence of Eocene growth-strata ( 44-40 Ma) suggests that contraction in the Andes and the Patagonian broken foreland was linked to the Incaic phase. Detection of synextensional deposits suggests that the broken foreland collapsed partially during Oligocene to early Miocene. During middle Miocene times, the Quechua contractional phase produced folding of Neogene volcanic rocks and olistostrome deposition at 17 Ma. Finally, the presented Te map shows that intraplate contraction related to Andean phases localized preferentially along weak lithospheric zones (Te < 15 km). Hence, the observed strain distribution in the PBF appears to be controlled by lateral variations in the lithospheric strength. Variations in this parameter could be related to thermo-mechanical weakening produced by intraplate rifting in Paleozoic-Mesozoic times.

  8. Petrography, geochemistry and tectonic setting of Salmabad Tertiary volcanic rocks, southeast of Sarbisheh, eastern Iran

    Directory of Open Access Journals (Sweden)

    Masoumeh Goodarzi

    2014-10-01

    is attributed to the mantle source, presumably metasomatized by the Sistan ocean subduction. The trace element features are consistent with the roles played by subducted sediments and fluid released from the subducted slab in magma genesis. Acknowledgements The authors would like to thank reviewers for the constructive comments which greatly contributed to the improvement of the manuscript. References Berberian, F., Muir, I.D., Pankhurst, R.J. and Berberian, M., 1982. Late Cretaceous and early Miocene Andean type plutonic activity in northern Makran and Central Iran. Journal of the Geological Society, 139(5: 605-614. Camp, V.E. and Griffis, R., 1982. Character, genesis and tectonic setting of igneous rocks in the Sistan suture zone, eastern Iran. Lithos, 15(3: 221-239. Gill, R., 2010. Igneous rocks and processes. Wiley-Blackwell, Malaysia, 428 pp. Harangi, S., Downes, H., Thirlwall, M., Gmeling, K., 2007. Geochemistry, Petrogenesis and Geodynamic Relationships of Miocene Calc-alkalineVolcanic Rocks in the Western Carpathian arc, Eastern Central Europe. Journal of petrology, 48(12: 2261-2287. Jung, D., Keller, J., Khorasani, R., Marcks, Chr., Baumann, A. and Horn, P., 1983. Petrology of the Tertiary magmatic activity the northern Lut area, East of Iran. Ministry of mines and metals, Geological survey of Iran, geodynamic project (geotraverse in Iran, Tehran, Report 51, pp. 285-336. Karimpour, M.H., Stern, C.R., Farmer, L., Saadat, S. and Malekezadeh, A., 2011. Review of age, Rb-Sr geochemistry and petrogenesis of Jurassic to Quaternary igneous rocks in Lut Block, Eastern Iran. Geopersia, 1(1:19-36. Kuscu, G.G. and Geneli, F., 2010. Review of post-collisional volcanism in the central Anatolian volcanic province(Turkey, with special reference to the Tepekoy volcanic complex. International Journal of Earth Sciences, 99(3: 593-621. Richards, J.P., Spell, T., Rameh, E., Razique, A. and Fletcher T., 2012. High Sr/Y Magmas Reflect Arc Maturity,High Magmatic Water Content, and

  9. The use of Remote Sensing for the Study of the Relationships Between Tectonics and Volcanism

    Science.gov (United States)

    Chorowicz, J.; Dhont, D.; Yanev, Y.; Bardintzeff, J.

    2004-12-01

    Observations of geometric relationships between tectonics and volcanism is a fruitful approach in geology. On the one hand analysis of the distribution and types of volcanic vents provides information on the geodynamics. On the other hand tectonic analysis explains the location of volcanics vents. Volcanic edifices often result from regional scale deformation, forming open structures constituting preferred pathways for the rise of magmas. Analysis of the shape and the distribution of vents can consequently provide data on the regional deformation. Remote sensing imagery gives synoptic views of the earth surface allowing the analysis of landforms of still active tectonic and volcanic features. Shape and distribution of volcanic vents, together with recent tectonic patterns are best observed by satellite data and Digital Elevation Models than in the field. The use of radar scenes for the study of the structural relationships between tectonic and volcanic features is particularly efficient because these data express sensitive changes in the morphology. In various selected areas, we show that volcanic edifices are located on tension fractures responsible for fissure eruptions, volcanic linear clusters and elongate volcanoes. Different types of volcanic emplacements can be also distinguished such as tail-crack or horse-tail features, and releasing bend basins along strike-slip faults. Caldera complexes seem to be associated to horse-tail type fault terminations. At a regional scale, the distribution of volcanic vents and their relationships with the faults is able to explain the occurrence of volcanism in collisional areas.

  10. Volcanic hazard studies for the Yucca Mountain project

    International Nuclear Information System (INIS)

    Crowe, B.; Turrin, B.; Wells, S.; Perry, F.; McFadden, L.; Renault, C.E.; Champion, D.; Harrington, C.

    1989-01-01

    Volcanic hazard studies are ongoing to evaluate the risk of future volcanism with respect to siting of a repository for disposal of high-level radioactive waste at the Yucca Mountain site. Seven Quaternary basaltic volcanic centers are located a minimum distance of 12 km and a maximum distance of 47 km from the outer boundary of the exploration block. The conditional probability of disruption of a repository by future basaltic volcanism is bounded by the range of 10/sup /minus/8/ to 10/sup /minus/10/ yr/sup /minus/1/. These values are currently being reexamined based on new developments in the understanding of the evaluation of small volume, basaltic volcanic centers including: (1) Many, perhaps most, of the volcanic centers exhibit brief periods of eruptive activity separated by longer periods of inactivity. (2) The centers may be active for time spans exceeding 10 5 yrs, (3) There is a decline in the volume of eruptions of the centers through time, and (4) Small volume eruptions occurred at two of the Quaternary centers during latest Pleistocene or Holocene time. We classify the basalt centers as polycyclic, and distinguish them from polygenetic volcanoes. Polycyclic volcanism is characterized by small volume, episodic eruptions of magma of uniform composition over time spans of 10 3 to 10 5 yrs. Magma eruption rates are low and the time between eruptions exceeds the cooling time of the magma volumes. 25 refs., 2 figs

  11. Seismic imaging of the upper mantle beneath the northern Central Andean Plateau: Implications for surface topography

    Science.gov (United States)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Wagner, L. S.

    2015-12-01

    Extending over 1,800 km along the active South American Cordilleran margin, the Central Andean Plateau (CAP) as defined by the 3 km elevation contour is second only to the Tibetan Plateau in geographic extent. The uplift history of the 4 km high Plateau remains uncertain with paleoelevation studies along the CAP suggesting a complex, non-uniform uplift history. As part of the Central Andean Uplift and the Geodynamics of High Topography (CAUGHT) project, we use surface waves measured from ambient noise and two-plane wave tomography to image the S-wave velocity structure of the crust and upper mantle to investigate the upper mantle component of plateau uplift. We observe three main features in our S-wave velocity model including (1), a high velocity slab (2), a low velocity anomaly above the slab where the slab changes dip from near horizontal to a normal dip, and (3), a high-velocity feature in the mantle above the slab that extends along the length of the Altiplano from the base of the Moho to a depth of ~120 km with the highest velocities observed under Lake Titicaca. A strong spatial correlation exists between the lateral extent of this high-velocity feature beneath the Altiplano and the lower elevations of the Altiplano basin suggesting a potential relationship. Non-uniqueness in our seismic models preclude uniquely constraining this feature as an uppermost mantle feature bellow the Moho or as a connected eastward dipping feature extending up to 300 km in the mantle as seen in deeper mantle tomography studies. Determining if the high velocity feature represents a small lithospheric root or a delaminating lithospheric root extending ~300 km into the mantle requires more integration of observations, but either interpretation shows a strong geodynamic connection with the uppermost mantle and the current topography of the northern CAP.

  12. Effects of Flat Slab Subduction on Andean Thrust Kinematics and Foreland Basin Evolution in Western Argentina

    Science.gov (United States)

    Horton, B. K.; Fuentes, F.; McKenzie, N. R.; Constenius, K. N.; Alvarado, P. M.

    2014-12-01

    Debate persists over the effects of flat-slab subduction on the kinematics of overriding plate deformation and the evolution of retroarc sedimentary basins. In western Argentina, major spatial and temporal variations in the geometry of the subducting Nazca slab since ~15 Ma provide opportunities to evaluate the late Cenozoic response of the Andean fold-thrust belt and foreland basin to subhorizontal subduction. Preliminary results from several structural and sedimentary transects spanning the frontal thrust belt and foreland basin system between 31°S and 35°S reveal Oligocene-middle Miocene hinterland exhumation during normal-slab subduction followed thereafter by progressive slab shallowing with initial rapid cratonward propagation of ramp-flat thrust structures (prior to basement-involved foreland uplifts) and accompanying wholesale exhumation and recycling of the early Andean foreland basin (rather than regional dynamic subsidence). Detrital zircon U-Pb geochronologic data prove instrumental for revealing shifts in thrust-belt exhumation, defining depositional ages within the foreland basin, and constraining the timing of activity along frontal thrust structures. In both the San Juan (31-32°S) and Malargüe (34-35°S) segments of the fold-thrust belt, geochronological results for volcaniclastic sandstones and syndeformational growth strata are consistent with a major eastward advance in shortening at 12-9 Ma. This episode of rapid thrust propagation precedes the reported timing of Sierras Pampeanas basement-involved foreland uplifts and encompasses modern regions of both normal- and flat-slab subduction, suggesting that processes other than slab dip (such as inherited crustal architecture, critical wedge dynamics, and arc magmatism) are additional regulators of thrust-belt kinematics and foreland basin evolution.

  13. 75 FR 73118 - Agency Information Collection Activities: Andean Trade Preferences

    Science.gov (United States)

    2010-11-29

    ... Management and Budget (OMB) approval. All comments will become a matter of public record. In this document... through 3206. The ATPA Certificate of Origin format is found under the CBP Regulations, 19 CFR 10.201-10... collected or to CBP Form 449. Type of Review: Extension (without change). Affected Public: Businesses. ATPA...

  14. Climate change forces new ecological states in tropical Andean lakes.

    Directory of Open Access Journals (Sweden)

    Neal Michelutti

    Full Text Available Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources.

  15. Andean rural children's views of the environment: A qualitative study

    Science.gov (United States)

    Maurial, Mahia

    Andean rural children's drawings and narratives about their crops and the immediate biological environment are rich tools to understand local views of the environment. Children's drawings and narratives were collected and linked to interviews as well as participant observation gathered from parents, leaders and teachers. The research sites are the community of Willca and the school of Mayu. Fieldwork was completed in 1998. In the conceptual framework I distinguish between two dissimilar knowledges, school knowledge and local knowledge. These knowledges produce two dissimilar views of the environment. I further analyze relationships of knowledge and power and argue that school knowledge overpowers local knowledge. Concomitantly, I studied set of ideas associated with two knowledges aforementioned: superacion (surpass) and regeneration (Apffel-Marglin 1995). Although these ideas coexist in peoples' minds they are not linked or effectively connected. In order to link local knowledge and school knowledge together, I propose the integration of environmental studies and art education to enhance a local sense of place (Blandy et. al 1993) in Andean and other schools. This will contribute to grassroots educational policy.

  16. Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process

    Science.gov (United States)

    García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón

    2014-06-01

    The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

  17. Large Volcanic Rises on Venus

    Science.gov (United States)

    Smrekar, Suzanne E.; Kiefer, Walter S.; Stofan, Ellen R.

    1997-01-01

    Large volcanic rises on Venus have been interpreted as hotspots, or the surface manifestation of mantle upwelling, on the basis of their broad topographic rises, abundant volcanism, and large positive gravity anomalies. Hotspots offer an important opportunity to study the behavior of the lithosphere in response to mantle forces. In addition to the four previously known hotspots, Atla, Bell, Beta, and western Eistla Regiones, five new probable hotspots, Dione, central Eistla, eastern Eistla, Imdr, and Themis, have been identified in the Magellan radar, gravity and topography data. These nine regions exhibit a wider range of volcano-tectonic characteristics than previously recognized for venusian hotspots, and have been classified as rift-dominated (Atla, Beta), coronae-dominated (central and eastern Eistla, Themis), or volcano-dominated (Bell, Dione, western Eistla, Imdr). The apparent depths of compensation for these regions ranges from 65 to 260 km. New estimates of the elastic thickness, using the 90 deg and order spherical harmonic field, are 15-40 km at Bell Regio, and 25 km at western Eistla Regio. Phillips et al. find a value of 30 km at Atla Regio. Numerous models of lithospheric and mantle behavior have been proposed to interpret the gravity and topography signature of the hotspots, with most studies focusing on Atla or Beta Regiones. Convective models with Earth-like parameters result in estimates of the thickness of the thermal lithosphere of approximately 100 km. Models of stagnant lid convection or thermal thinning infer the thickness of the thermal lithosphere to be 300 km or more. Without additional constraints, any of the model fits are equally valid. The thinner thermal lithosphere estimates are most consistent with the volcanic and tectonic characteristics of the hotspots. Estimates of the thermal gradient based on estimates of the elastic thickness also support a relatively thin lithosphere (Phillips et al.). The advantage of larger estimates of

  18. The evolution of witchcraft and the meaning of healing in colonial Andean society.

    Science.gov (United States)

    Silverblatt, I

    1983-12-01

    This paper explores the ways in which traditional beliefs of Andean peoples regarding health and sickness were transformed by the process of Spanish colonization. It also examines how the colonial context devolved new meanings and powers on native curers. The analysis of these transformations in Andean systems of meanings and role structures relating to healing depends on an examination of the European witchcraze of the 16th-17th centuries. The Spanish conquest of the Inca empire in the mid-1500's coincided with the European witch hunts; it is argued that the latter formed the cultural lens through which the Spanish evaluated native religion--the matrix through which Andean concepts of disease and health were expressed--as well as native curers. Andean religion was condemned as heresy and curers were condemned as witches. Traditional Andean cosmology was antithetical to 16th century European beliefs in the struggle between god and the devil, between loyal Christians and the Satan's followers. Consequently, European concepts of disease and health based on the power of witches, Satan's adherents, to cause harm and cure were alien to pre-Columbian Andean thought. Ironically European concepts of Satan and the supposed powers of witches began to graft themselves onto the world view of Andean peoples. The ensuing dialectic of ideas as well as the creation of new healers/witches forged during the imposition of colonial rule form the crux of this analysis.

  19. Pacific seamount volcanism in space and time

    Science.gov (United States)

    Hillier, J. K.

    2007-02-01

    Seamounts constitute some of the most direct evidence about intraplate volcanism. As such, when seamounts formed and into which tectonic setting they erupted (i.e. on-ridge or off-ridge) are a useful reflection of how the properties of the lithosphere interact with magma generation in the fluid mantle beneath. Proportionately few seamounts are radiometrically dated however, and these tend to be recently active. In order to more representatively sample and better understand Pacific seamount volcanism this paper estimates the eruption ages (tvolc) of 2706 volcanoes via automated estimates of lithospheric strength. Lithospheric strength (GTRrel) is deduced from the ratio of gravity to topography above the summits of volcanoes, and is shown to correlate with seafloor age at the time of volcanic loading (Δt) at 61 sites where radiometric constraints upon Δt exist. A trend of fits data for these 61, and with seafloor age (tsf) known, can date the 2706 volcanoes; tvolc = tsf - Δt. Widespread recurrences of volcanism proximal to older features (e.g. the Cook-Austral alignment in French Polynesia) suggest that the lithosphere exerts a significant element of control upon the location of volcanism, and that magmatic throughput leaves the lithosphere more susceptible to the passage of future melts. Observations also prompt speculation that: the Tavara seamounts share morphological characteristics and isostatic compensation state with the Musicians, and probably formed similarly; the Easter Island chain may be a modern analogy to the Cross-Lines; a Musicians - South Hawaiian seamounts alignment may be deflecting the Hawaiian hotspot trace.

  20. Cooling Rates of Lunar Volcanic Glass Beads

    Science.gov (United States)

    Hui, Hejiu; Hess, Kai-Uwe; Zhang, Youxue; Peslier, Anne; Lange, Rebecca; Dingwell, Donald; Neal, Clive

    2016-01-01

    It is widely accepted that the Apollo 15 green and Apollo 17 orange glass beads are of volcanic origin. The diffusion profiles of volatiles in these glass beads are believed to be due to degassing during eruption (Saal et al., 2008). The degree of degassing depends on the initial temperature and cooling rate. Therefore, the estimations of volatiles in parental magmas of lunar pyroclastic deposits depend on melt cooling rates. Furthermore, lunar glass beads may have cooled in volcanic environments on the moon. Therefore, the cooling rates may be used to assess the atmospheric condition in an early moon, when volcanic activities were common. The cooling rates of glasses can be inferred from direct heat capacity measurements on the glasses themselves (Wilding et al., 1995, 1996a,b). This method does not require knowledge of glass cooling environments and has been applied to calculate the cooling rates of natural silicate glasses formed in different terrestrial environments. We have carried out heat capacity measurements on hand-picked lunar glass beads using a Netzsch DSC 404C Pegasus differential scanning calorimeter at University of Munich. Our preliminary results suggest that the cooling rate of Apollo 17 orange glass beads may be 12 K/min, based on the correlation between temperature of the heat capacity curve peak in the glass transition range and glass cooling rate. The results imply that the parental magmas of lunar pyroclastic deposits may have contained more water initially than the early estimations (Saal et al., 2008), which used higher cooling rates, 60-180 K/min in the modeling. Furthermore, lunar volcanic glass beads could have been cooled in a hot gaseous medium released from volcanic eruptions, not during free flight. Therefore, our results may shed light on atmospheric condition in an early moon.

  1. Volcanism Studies: Final Report for the Yucca Mountain Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce M. Crowe; Frank V. Perry; Greg A. Valentine; Lynn M. Bowker

    1998-12-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone is

  2. Submarine Volcanic Eruptions and Potential Analogs for Venus

    Science.gov (United States)

    Wilson, L.; Mouginismark, P. J.; Fryer, P.; Gaddis, L. R.

    1985-01-01

    As part of an analysis program to better understand the diversity of volcanic processes on the terrestrial planets, an investigation of the volcanic landforms which exist on the Earth's ocean floor was initiated. In part, this analysis is focused toward gaining a better understanding of submarine volcanic landforms in their own right, but also it is hoped that these features may show similarities to volcanic landforms on Venus, due to the high ambient water (Earth) and atmospheric (Venus) pressures. A series of numerical modelling experiments was performed to investigate the relative importance of such attributes as water pressure and temperature on the eruption process, and to determine the rate of cooling and emplacement of lava flows in the submarine environment. Investigations to date show that the confining water pressure and the buoyancy effects of the surrounding water significantly affect the styles of volcanism on the ocean floor. In the case of Venusian volcanism, confining pressures will not be as great as that found at the ocean's abyssal plains, but nevertheless the general trend toward reducing magma vesiculation will hold true for Venus as well as the ocean floor. Furthermore, other analogs may also be found between submarine volcanism and Venusian activity.

  3. 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

  4. ASI-Sistema Rischio Vulcanico SRV: a pilot project to develop EO data processing modules and products for volcanic activity monitoring based on Italian Civil Protection Department requirements and needs

    Science.gov (United States)

    Buongiorno, Maria Fabrizia; Musacchio, Massimo; Silvestri, Malvina; Spinetti, Claudia; Corradini, Stefano; Lombardo, Valerio; Merucci, Luca; Sansosti, Eugenio; Pugnagli, Sergio; Teggi, Sergio; Pace, Gaetano; Fermi, Marco; Zoffoli, Simona

    2007-10-01

    The Project called Sistema Rischio Vulcanico (SRV) is funded by the Italian Space Agency (ASI) in the frame of the National Space Plan 2003-2005 under the Earth Observations section for natural risks management. The SRV Project is coordinated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) which is responsible at national level for the volcanic monitoring. The objective of the project is to develop a pre-operative system based on EO data and ground measurements integration to support the volcanic risk monitoring of the Italian Civil Protection Department which requirements and need are well integrated in the GMES Emergency Core Services program. The project philosophy is to implement, by incremental versions, specific modules which allow to process, store and visualize through Web GIS tools EO derived parameters considering three activity phases: 1) knowledge and prevention; 2) crisis; 3) post crisis. In order to combine effectively the EO data and the ground networks measurements the system will implement a multi-parametric analysis tool, which represents and unique tool to analyze contemporaneously a large data set of data in "near real time". The SRV project will be tested his operational capabilities on three Italian Volcanoes: Etna,Vesuvio and Campi Flegrei.

  5. Modelling ground deformation patterns associated with volcanic processes at the Okataina Volcanic Centre

    Science.gov (United States)

    Holden, L.; Cas, R.; Fournier, N.; Ailleres, L.

    2017-09-01

    The Okataina Volcanic Centre (OVC) is one of two large active rhyolite centres in the modern Taupo Volcanic Zone (TVZ) in the North Island of New Zealand. It is located in a complex section of the Taupo rift, a tectonically active section of the TVZ. The most recent volcanic unrest at the OVC includes the 1315 CE Kaharoa and 1886 Tarawera eruptions. Current monitoring activity at the OVC includes the use of continuous GPS receivers (cGPS), lake levelling and seismographs. The ground deformation patterns preceding volcanic activity the OVC are poorly constrained and restricted to predictions from basic modelling and comparison to other volcanoes worldwide. A better understanding of the deformation patterns preceding renewed volcanic activity is essential to determine if observed deformation is related to volcanic, tectonic or hydrothermal processes. Such an understanding also means that the ability of the present day cGPS network to detect these deformation patterns can also be assessed. The research presented here uses the finite element (FE) modelling technique to investigate ground deformation patterns associated with magma accumulation and diking processes at the OVC in greater detail. A number of FE models are produced and tested using Pylith software and incorporate characteristics of the 1315 CE Kaharoa and 1886 Tarawera eruptions, summarised from the existing body of research literature. The influence of a simple ring fault structure at the OVC on the modelled deformation is evaluated. The ability of the present-day continuous GPS (cGPS) GeoNet monitoring network to detect or observe the modelled deformation is also considered. The results show the modelled horizontal and vertical displacement fields have a number of key features, which include prominent lobe based regions extending northwest and southeast of the OVC. The results also show that the ring fault structure increases the magnitude of the displacements inside the caldera, in particular in the

  6. Lidar detection of carbon dioxide in volcanic plumes

    Science.gov (United States)

    Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Maio, Giovanni; Del Franco, Mario; Aiuppa, Alessandro

    2015-06-01

    Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. Two differential absorption lidar instruments will be presented in this paper: BILLI (BrIdge voLcanic LIdar), based on injection seeded Nd:YAG laser, double grating dye laser, difference frequency mixing (DFM) and optical parametric amplifier (OPA), and VULLI (VULcamed Lidar), based on injection seeded Nd:YAG laser and optical parametric oscillator (OPO). The first one is funded by the ERC (European Research Council) project BRIDGE and the second one by the ERDF (European Regional Development Fund) project VULCAMED. While VULLI has not yet been tested in a volcanic site, BILLI scanned the gas emitted by Pozzuoli Solfatara (Campi Flegrei volcanic area, Naples, Italy) during a field campaign carried out from 13 to 17 October 2014. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater area. Lidar measurements were in good agreement with well-established techniques, based on different operating principles. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar, representing the first direct measurement of this kind ever performed on an active volcano and showing the high potential of laser remote sensing in geophysical research.

  7. A new minute Andean Pristimantis (Anura: Strabomantidae from Venezuela

    Directory of Open Access Journals (Sweden)

    César L. Barrio-Amorós

    2012-12-01

    Full Text Available A new species of Pristimantis is described from the Venezuelan Andes. The new species is the smallest in its genus known in Venezuela and belongs to the Pristimantis unistrigatus Group. It differs from the rest of Venezuelan Andean congeners in body size (mean male SVL < 21.3 mm, female SVL < 26.3 mm, expanded discs on fingers and toes, absence of dorsolateral folds, and a distinctivecall consisting in 2–5 cricket-like short notes. The new species inhabits the southwestern part of the Cordillera de Mérida in Venezuela and the Venezuelan side of the Cordillera Oriental deColombia, and could be present on the Colombian portion of the cordillera as well.

  8. Biodegradability and mechanical properties of starch films from Andean crops.

    Science.gov (United States)

    Torres, F G; Troncoso, O P; Torres, C; Díaz, D A; Amaya, E

    2011-05-01

    Different Andean crops were used to obtain starches not previously reported in literature as raw material for the production of biodegradable polymers. The twelve starches obtained were used to prepare biodegradable films by casting. Water and glycerol were used as plasticizers. The mechanical properties of the starch based films were assessed by means of tensile tests. Compost tests and FTIR tests were carried out to assess biodegradability of films. The results show that the mechanical properties (UTS, Young's modulus and elongation at break) of starch based films strongly depend on the starch source used for their production. We found that all the starch films prepared biodegrade following a three stage process and that the weight loss rate of all the starch based films tested was higher than the weight loss rate of the cellulose film used as control. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Bioactive Potential of Andean Fruits, Seeds, and Tubers.

    Science.gov (United States)

    Campos, David; Chirinos, Rosana; Gálvez Ranilla, Lena; Pedreschi, Romina

    2018-01-01

    The Andes is considered the longest continental mountain range in the world. It covers 7000km long and about 200-700km wide and an average height of about 4000m. Very unique plant species are endemic of this area including fruits (e.g., lucuma, cherimoya, sweet pepino, sauco), roots and tubers (potatoes, sweet potatoes, yacón, chicuru, mashua, olluco, etc.), and seeds (quinoa, amaranth, tarwi, etc.). These crops have been used for centuries by the native population and relatively recently have gained the world attention due to the wide range of nutrients and/or phytochemicals they possess. In this chapter, main Andean fruits, seeds, and roots and tubers have been selected and detailed nutritional and functional information is provided. In addition, traditional and current uses are provided and their bioactive potential is reported based on published scientific literature. © 2018 Elsevier Inc. All rights reserved.

  10. [Elaboration and evaluation of infant food based on Andean crops].

    Science.gov (United States)

    Repo-Carrasco, R; Hoyos, N L

    1993-06-01

    The Andes mountain range of South America is one of the most important centres for crop domestication, potato, corn, and lesser known grains such as quinua, cañihua, kiwicha and tarwi are indigenous of these highlands. These Andean grains have adapted perfectly to the climatic and geographical conditions present, whereas other grains have not been able to survive. In addition to their hardiness, they also have a high nutritional value. Bearing in mind on one hand, the high nutritional value of these indegenous products, and on the other hand the high rate of child malnutrition prevalent in the population, it was considered important to look for new variations in their processing which would facilitate their consumption by the poor working classes, especially the children. Accordingly three different flour mixtures were developed based on these Andean grains, the mixtures were then subjected to bromatological and biological analysis. The three new flour mixtures were: Quinua-Cañihua-Broad Bean (Q-C-B), Quinua-Kiwicha-Bean (Q-K-B) and Kiwicha-Rice (K-R). The protein content of these mixtures varied between 11.35-15.46 g/100g, the mixture K-R having the lowest protein level and the Q-C-B having the highest. The Q-K-B mixture had the highest chemical score, PER and NPU value. This PER value of 2.59 was higher than the value of casein which was 2.50. In addition this mixture had a chemical score of 0.94 and a NPU value of 59.38. The Q-C-B mixture had a chemical score of 0.88 and its PER, NPU and Digestibility values were 2.36, 47.24 and 79.2 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Genetic diversity of Phytophthora infestans in the Northern Andean region.

    Science.gov (United States)

    Cárdenas, Martha; Grajales, Alejandro; Sierra, Roberto; Rojas, Alejandro; González-Almario, Adriana; Vargas, Angela; Marín, Mauricio; Fermín, Gustavo; Lagos, Luz E; Grünwald, Niklaus J; Bernal, Adriana; Salazar, Camilo; Restrepo, Silvia

    2011-02-09

    Phytophthora infestans (Mont.) de Bary, the causal agent of potato late blight, is responsible for tremendous crop losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato, and more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana) and tree tomato (Solanum betaceum), all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly understood in Colombia and Venezuela. To understand the P. infestans population structure in the Northern part of the Andes, four nuclear regions (ITS, Ras, β-tubulin and Avr3a) and one mitochondrial (Cox1) region were analyzed in isolates of P. infestans sampled from different hosts in Colombia and Venezuela. Low genetic diversity was found within this sample of P. infestans isolates from crops within several regions of Colombia and Venezuela, revealing the presence of clonal populations of the pathogen in this region. We detected low frequency heterozygotes, and their distribution patterns might be a consequence of a high migration rate among populations with poor effective gene flow. Consistent genetic differentiation exists among isolates from different regions. The results here suggest that in the Northern Andean region P. infestans is a clonal population with some within-clone variation. P. infestans populations in Venezuela reflect historic isolation that is being reinforced by a recent self-sufficiency of potato seeds. In summary, the P. infestans population is mainly shaped by migration and probably by the appearance of variants of key effectors such as Avr3a.

  12. Genetic diversity of Phytophthora infestans in the Northern Andean region

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    Grünwald Niklaus J

    2011-02-01

    Full Text Available Abstract Background Phytophthora infestans (Mont. de Bary, the causal agent of potato late blight, is responsible for tremendous crop losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato, and more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana and tree tomato (Solanum betaceum, all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly understood in Colombia and Venezuela. To understand the P. infestans population structure in the Northern part of the Andes, four nuclear regions (ITS, Ras, β-tubulin and Avr3a and one mitochondrial (Cox1 region were analyzed in isolates of P. infestans sampled from different hosts in Colombia and Venezuela. Results Low genetic diversity was found within this sample of P. infestans isolates from crops within several regions of Colombia and Venezuela, revealing the presence of clonal populations of the pathogen in this region. We detected low frequency heterozygotes, and their distribution patterns might be a consequence of a high migration rate among populations with poor effective gene flow. Consistent genetic differentiation exists among isolates from different regions. Conclusions The results here suggest that in the Northern Andean region P. infestans is a clonal population with some within-clone variation. P. infestans populations in Venezuela reflect historic isolation that is being reinforced by a recent self-sufficiency of potato seeds. In summary, the P. infestans population is mainly shaped by migration and probably by the appearance of variants of key effectors such as Avr3a.

  13. Geophysical expression of caldera related volcanism, structures and mineralization in the McDermitt volcanic field

    Science.gov (United States)

    Rytuba, J. J.; Blakely, R. J.; Moring, B.; Miller, R.

    2013-12-01

    30 km trend that then arcs NE into the caldera. These anomalies reflect near surface rhyolite intrusions that underlie the caldera-fill sediments that have been altered to K-feldpar and clay minerals. K gamma ray anomalies also delineate this zone of alteration. The last phase of volcanism occurs in the central part of the caldera and is associated with a broad aeromagnetic high with individual high-amplitude aeromagnetic highs coincident with three large volcanic vents. No hydrothermal alteration is associated with this last phase of volcanism. On the SW side of the McDermitt volcanic field a 10 km wide, 60 km long, NNW-trending zone of late Miocene normal faults developed after cessation of volcanism and prior to Basin and Range faulting. We propose that this extensional fault zone is the eastern continuation of the NW trending Brothers Fault Zone, but changes to a NNW trend where it is deflected by the plutons that underlies the McDermitt volcanic field. Plutons that underlie all three of these Mid Miocene volcanic fields have minimized post-caldera extensional faulting. Thus only caldera ring fracture faults were available for the development of hydrothermal systems in areas where post caldera intrusive activity was localized.

  14. Closer look at lunar volcanism

    International Nuclear Information System (INIS)

    Vaniman, D.T.; Heiken, G.; Taylor, G.J.

    1984-01-01

    Although the American Apollo and Soviet Luna missions concentrated on mare basalt samples, major questions remain about lunar volcanism. Lunar field work will be indispensable for resolving the scientific questions about ages, compositions, and eruption processes of lunar volcanism. From a utilitarian standpoint, a better knowledge of lunar volcanism will also yield profitable returns in lunar base construction (e.g., exploitation of rille or lava-tube structures) and in access to materials such as volatile elements, pure glass, or ilmenite for lunar industry

  15. Volcanic emission of radionuclides and magma dynamics

    International Nuclear Information System (INIS)

    Lambert, G.; Le Cloarec, M.F.; Ardouin, B.; Le Roulley, J.C.

    1985-01-01

    210 Pb, 210 Bi and 210 Po, the last decay products of the 238 U series, are highly enriched in volcanic plumes, relative to the magma composition. Moreover this enrichment varies over time and from volcano to volcano. A model is proposed to describe 8 years of measurements of Mt. Etna gaseous emissions. The lead and bismuth coefficients of partition between gaseous and condensated phases in the magma are determined by comparing their concentrations in lava flows and condensated volatiles. In the case of volatile radionuclides, an escaping time is calculated which appears to be related to the volcanic activity. Finally, it is shown that that magma which is degassing can already be partly degassed; it should be considered as a mixture of a few to 50% of deep non-degassed magma with a well degassed superficial magma cell. (orig.)

  16. 40Ar/39Ar laster fusion and K-Ar ages from Lathrop Wells, Nevada, and Cima, California: The age of the latest volcanic activity in the Yucca Mountain area

    International Nuclear Information System (INIS)

    Turrin, B.D.; Champion, D.E.

    1991-01-01

    K-Ar and 40 Ar/ 39 Ar ages from the Lathrop Wells volcanic center, Nevada, and from the Cima volcanic field, California, indicate that the recently reported 20-ka age estimate for the Lathrop Wells volcanic center is incorrect. Instead, an age of 119 ± 11 to 141 ± 10 ka is indicated for the Lathrop Wells volcanic center. This age corrected is concordant with the ages determined by two independent isotopic geochronometric techniques and with the stratigraphy of surficial deposits in the Yucca Mountain region. In addition, paleomagnetic data and radiometric age data indicate only two volcanic events at the Lathrop Wells volcanic center that are probably closely linked in time, not as many as five as recently reported. 32 refs., 2 figs., 2 tabs

  17. Self-potential anomalies in some Italian volcanic areas

    Directory of Open Access Journals (Sweden)

    C. Silenziario

    1996-06-01

    Full Text Available The study of Self-Potential (SP space and time variations in volcanic areas may provide useful information on both the geometrical structure of the volcanic apparatuses and the dynamical behaviour of the feeding and uprising systems. In this paper, the results obtained on the islands of Vulcano (Eolian arc and Ponza (Pontine archipelago and on the Mt. Somma-Vesuvius complex are shown. On the island of Vulcano and on the Mt. Somma-Vesuvius apparatus areal SP surveys were performed with the aim of evidencing anomalies closely associated to the zones of major volcanic activity. On the island of Vulcano a profile across the fumaroles along the crater rim of the Fossa Cone was also carried out in order to have a direct relationship between fumarolic fracture migration and flow rate and SP anomaly space and time variations. The areal survey on the island of Ponza, which is considered an inactive area, is assumed as a reference test with which to compare the amplitude and pattern of the anomalies in the active areas. A tentative interpretation of the SP anomalies in volcanic areas is suggested in terms of electrokinetic phenomena, related to the movement of fluids of both volcanic and non-volcanic origin.

  18. From Dearth to El Dorado: Andean Nature, Plate Tectonics, and the Ontologies of Ecuadorian Resource Wealth

    Directory of Open Access Journals (Sweden)

    David Kneas

    2018-03-01

    Full Text Available Since the early 1990s, the Ecuadorian government has pledged to convert the nation into a “mining country” of global standing. Contemporary claims of mineral wealth, however, stand in stark contrast to previous assessments. Indeed, through much of the 20th century, geologists described Ecuador as a country of mineral dearth. Exploring the process through which Ecuador seemingly transitioned from a nation of resource scarcity to one of mineral plenty, I demonstrate how assessments of Ecuador’s resource potential relate to ideas of Andean nature. Promoters of resource abundance have emphasized Andean uniformity and equivalence—the notion that Ecuador’s mineral wealth is inevitable by virtue of the resource richness of its Andean neighbors. Geologists who have questioned Ecuador’s mineral content, on the other hand, have emphasized Andean heterogeneity. In the recent promotion of Ecuador’s resource potential, notions of Andean uniformity have been bolstered by models of subsoil copper that emerged in the in 1970s in the context of plate-tectonic theory. In highlighting the linkage between ideas of Andean nature and appraisals of Ecuadorian resource potential since the late 19th century, I outline the dialectics between nature and natural resources that underpin processes of resource becoming.

  19. Glacial evolution of the Ampato Volcanic Complex (Peru)

    Science.gov (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.; Vázquez, L.

    2009-04-01

    Ice masses on the Western range of the Central Andes are a main source of water resources and act as a geoindicator of variations in the climate of the tropics (Mark, 2008). The study of their evolution is of particular interest since they are situated in the transition zone between the tropical and mid-latitude circulation areas of the atmosphere (Zech et al., 2007). The function of this transition area is currently under debate, and understanding it is essential for the development of global climate models (Kull et al, 2008; Mark, 2008). However our understanding of the evolution of glaciers and their paleoclimatic factors for this sector of the Central Andes is still at a very basic level. This paper presents initial results of a study on the glacial evolution of the Ampato volcanic complex (15°24´- 15° 51´ S, 71° 51´ - 73° W; 6288 m a.s.l.) located in the Western Range of the Central Andes in Southern Peru, 70 km NW of the city of Arequipa. The main objectives are to identify the number of glacial phases the complex has undergone using geomorphological criteria to define a time frame for each phase, based on cosmogenic 36Cl dating of a sequence of moraine deposits; and to estimate the glacier Equilibrium Line Altitude (ELA) of each phase. The Ampato volcanic complex is formed by 3 great andesitic stratovolcanoes, the Nevados HualcaHualca-Sabancaya-Ampato, which started forming between the late Miocene and early Quaternary (Bulmer et al., 1999), aligned N-S and with summits covered with glaciers. The Sabancaya volcano is fully active, with its latest eruption occurring in 2001. Glacial landforms were identified and mapped using photointerpretation of vertical aerial photographs from 1955 (1:35,000 scale, National Geographic Institute of Peru), oblique photographs from 1943 (Aerophotographical Service of Peru), and a geo-referenced high-resolution Mrsid satellite image from 2000 (NASA). This cartography was corrected and improved through fieldwork. It was

  20. Detrital Zircon Provenance Record of Pre-Andean to Modern Tectonics in the Northern Andes: Examples from Peru, Ecuador, and Colombia

    Science.gov (United States)

    George, S. W. M.; Jackson, L. J.; Horton, B. K.

    2015-12-01

    Detrital zircon U-Pb age distributions from modern rivers and Mesozoic-Cenozoic basin fill in the northern Andes provide insights into pre-Andean, Andean, and active uplift and exhumation of distinctive sediment source regions. Diagnostic age signatures enable straightforward discrimination of competing sediment sources within the Andean magmatic arc (Western Cordillera-Central Cordillera), retroarc fold-thrust belt (Eastern Cordillera-Subandean Zone), and Amazonian craton (composed of several basement provinces). More complex, however, are the mid/late Cenozoic provenance records generated by recycling of basin fill originally deposited during early/mid Mesozoic extension, late Mesozoic thermal subsidence, and early Cenozoic shortening. Although subject to time-transgressive trends, regionally significant provenance patterns in Peru, Ecuador, and Colombia reveal: (1) Triassic-Jurassic growth of extensional subbasins fed by local block uplifts (with commonly unimodal 300­-150 Ma age peaks); (2) Cretaceous deposition in an extensive postrift setting fed by principally cratonic sources (with common 1800-900 Ma ages); and (3) Cenozoic growth of a broad flexural basin fed initially fed by magmatic-arc rocks (100-0 Ma), then later dominance by thrust-belt sedimentary rocks with progressively greater degrees of basin recycling (yielding diverse and variable age populations from the aforementioned source regions). U-Pb results from modern rivers and smaller subbasins prove useful in evaluating source-to-sink relationships, downstream mixing relationships, hinterland-foreland basin connectivity, paleodrainage integration, and tectonic/paleotopographic reconstructions. Most but not all of the elevated intermontane basins in the modern hinterland of the northern Andes contain provenance records consistent with genesis in a broader foreland basin developed at low elevation. Downstream variations within modern axial rivers and Cenozoic axial basins inform predictive models of

  1. Education can improve the negative perception of a threatened long-lived scavenging bird, the Andean condor

    Science.gov (United States)

    Cailly Arnulphi, Verónica B.; Lambertucci, Sergio A.

    2017-01-01

    Human-wildlife conflicts currently represent one of the main conservation problems for wildlife species around the world. Vultures have serious conservation concerns, many of which are related to people's adverse perception about them due to the belief that they prey on livestock. Our aim was to assess local perception and the factors influencing people's perception of the largest scavenging bird in South America, the Andean condor. For this, we interviewed 112 people from Valle Fértil, San Juan province, a rural area of central west Argentina. Overall, people in the area mostly have an elementary education, and their most important activity is livestock rearing. The results showed that, in general, most people perceive the Andean condor as an injurious species and, in fact, some people recognize that they still kill condors. We identified two major factors that affect this perception, the education level of villagers and their relationship with livestock ranching. Our study suggests that conservation of condors and other similar scavengers depends on education programs designed to change the negative perception people have about them. Such programs should be particularly focused on ranchers since they are the ones who have the worst perception of these scavengers. We suggest that highlighting the central ecological role of scavengers and recovering their cultural value would be fundamental to reverse their persecution and their negative perception by people. PMID:28950019

  2. Volcanology: Volcanic bipolar disorder explained

    Science.gov (United States)

    Jellinek, Mark

    2014-02-01

    Eruptions come in a range of magnitudes. Numerical simulations and laboratory experiments show that rare, giant super-eruptions and smaller, more frequent events reflect a transition in the essential driving forces for volcanism.

  3. Lidar sounding of volcanic plumes

    Science.gov (United States)

    Fiorani, Luca; Aiuppa, Alessandro; Angelini, Federico; Borelli, Rodolfo; Del Franco, Mario; Murra, Daniele; Pistilli, Marco; Puiu, Adriana; Santoro, Simone

    2013-10-01

    Accurate knowledge of gas composition in volcanic plumes has high scientific and societal value. On the one hand, it gives information on the geophysical processes taking place inside volcanos; on the other hand, it provides alert on possible eruptions. For this reasons, it has been suggested to monitor volcanic plumes by lidar. In particular, one of the aims of the FP7 ERC project BRIDGE is the measurement of CO2 concentration in volcanic gases by differential absorption lidar. This is a very challenging task due to the harsh environment, the narrowness and weakness of the CO2 absorption lines and the difficulty to procure a suitable laser source. This paper, after a review on remote sensing of volcanic plumes, reports on the current progress of the lidar system.

  4. Timing and compositional evolution of Late Pleistocene to Holocene volcanism within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia

    Science.gov (United States)

    Stelten, M. E.; Downs, D. T.; Dietterich, H. R.

    2017-12-01

    Harrat Rahat is one of the largest ( 20,000 km2) of 15 active Cenozoic volcanic fields that stretch 3,000 km along the western Arabian Peninsula from Yemen to Syria. The Harrat Rahat volcanic field is 310 km long (N-S) by 75 km wide (E-W), and is dominated by alkalic basalts with minor hawaiite, mugearite, benmoreite, and trachyte eruptives. The timing of volcanism within greater Harrat Rahat is poorly constrained, but field relations and geochronology indicate that northern Harrat Rahat hosted the most recent eruptions. To better constrain the timing and compositional evolution of Harrat Rahat during this recent phase, we present 743 geochemical analyses, 144 40Ar/39Ar ages, and 9 36Cl exposure ages for volcanic strata from northernmost Harrat Rahat. These data demonstrate that volcanism has been ongoing from at least 1.2 Ma to the present, with the most recent eruption known from historical accounts at 1256 CE. Basalt has erupted persistently from 1.2 Ma to the present, but more evolved volcanism has been episodic. Benmoreite erupted at 1.1 Ma and between 550 to 400 ka. Trachytic volcanism has only occurred over the past 150 ka, with the most recent eruption at 5 ka. Aside from the well-documented basaltic eruption at 1256 CE, prior workers interpreted 6 additional basaltic eruptions during the Holocene. However, our 36Cl exposure ages demonstrate that these erupted between 60 to 13 ka. Interestingly, in the northern part of our field area, where the spatial density of volcanic vents is low, young volcanism (<150 ka) is dominated by basaltic eruptions. Conversely, young volcanism in the southern part of our field area, where volcanic vent density is high, is dominated by trachyte. This observation is consistent with a process wherein the time-integrated effects of basaltic influx into the crust in the south produced a mafic intrusive complex, through which younger basaltic magmas cannot ascend. Instead, these magmas stall and produce trachyte, likely through

  5. Volcanic crisis in

    Directory of Open Access Journals (Sweden)

    Mgs. Víctor Manuel Pérez Martínez

    2007-01-01

    Full Text Available The article is the result of an investigation which is focussed on some deontological aspects of the scientificjournalism. In the first place it gives a theoretical vision about science, journalism, internet and including some reflectionsabout the deontological principles in handling the information about science and technology. This focus is useful as it formsthe base of an investigation where we deal with the information about a possible ”volcanic crisis” in El Teide during the years2004-2005 done by the digital newspaper” El Dïa” a canarian newspaper from Tenerife. The work required the revision of theinformation which was published and a followed analysis of its context. It was used the digital version with the purpose ofvisualizing the news which was published. It was also compared with a printed version, with local cover but divulged theinformation to the public who was most affected by this particular news. The results give rise to some questions regardinghow the information is given to a topic which is of local interest as well as national and international interest due to therepercussions in the social, economical and tourist field (the tourist field is the main industrial sector in Tenerife by receivingthis type of news.

  6. Geomicrobiological exploration and characterization of novel deep-sea hydrothermal activities accompanying with extremely acidic white smokers and elemental sulfur chimneys at the TOTO caldera in the Mariana Volcanic Arc

    Science.gov (United States)

    Takai, K.; Nakagawa, T.; Suzuki, Y.; Hirayama, H.; Kosaka, A.; Tsunogai, U.; Gamo, T.; Nealson, K. H.; Horikoshi, K.

    2004-12-01

    Novel hydrothermal activities accompanying effluent white smokers and elemental sulfur chimney structures at the northeast lava dome of the TOTO caldera depression in the Mariana Volcanic Arc were explored by the manned submersible Shinkai 6500 and characterized by geochemical and microbiological surveys. The white smoker hydrothermal fluids were observed in the potential hydrothermal activity center of the field and represented a maximal temperature of 172 degree C and a lowest pH of 1.59, that was the lowest pH of the hydrothermal fluid ever recorded. The chimney structures consisting all of elemental sulfur (sulfur chimney) were also peculiar to the TOTO caldera hydrothermal field in the world. The geochemical characterization strongly suggested that the TOTO caldera hydrothermal field was a novel system driven by subseafloor mixing between the oxygenated seawater and the superheated volcanic gasses. Microbial community structures in a sulfur chimney structure and its formation hydrothermal fluid with a high concentration of hydrogen sulfide (15 mM) were investigated by culture-dependent and _|independent analyses. Ribosomal rRNA gene clone analysis and fluorescence in situ hybridization (FISH) analysis revealed that epsilon-Proteobacteria, specifically classified into Group G and Group B, dominated the microbial communities in the sulfur chimney structure and formed a dense microbial mat covering the sulfur chimney surface. Archaeal phylotypes were consistently minor components in the communities and related to the genera Thermococcus, Pyrodictium, Aeropyrum, and the uncultivated archaeal group of Deep-sea Hydrothermal Vent Euryarchaeotal Group. Cultivation analysis suggested that the microbial components inhabiting in the sulfur chimney structure might be entrained by hydrothermal fluids from the potential subsurface habitats

  7. Monitoring the Sumatra volcanic arc with InSAR

    Science.gov (United States)

    Chaussard, E.; Hong, S.; Amelung, F.

    2009-12-01

    The Sumatra volcanic arc is the result of the subduction of the Indo-Australian plate under the Sunda plate. The arc consists of 35 known volcanic centers, subaerials on the west coast of the Sumatra and Andaman Islands and submarines between these islands. Six active centers are known in the Sumatra volcanic arc. Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Here we present a satellite-based Interferometric synthetic aperture radar (InSAR) survey of the Sumatra volcanic arc using ALOS data. Spanning the years 2007 to beginning of 2009, our survey reveals the background level of activity of the 35 volcanoes. We processed data from 40 tracks (24 in descending orbit and 16 in ascending orbit) to cover the whole Sumatra arc. In the first results five of these six known active centers show no sign of activity: Dempo, Kaba, Marapi, Talang and Peuet. The remaining active volcano, Mount Kerinci, has an ambiguous signal. We used pair-wise logic and InSAR time series of the available ALOS data to determine if the observed InSAR signal is caused by ground deformation or by atmospheric delays.

  8. Radon gas as a tracer for volcanic processes

    International Nuclear Information System (INIS)

    Thomas, D.M.

    1990-01-01

    Radon emissions from volcanic systems have been under investigation for several decades. Soil gas and groundwater radon activities have been used to map faults and to characterize geothermal systems, and measurements of atmospheric radon and radon daughter concentrations have been used to estimate the volume of magma chambers feeding active eruptions. Several studies have also shown that temporal variations in radon concentration have been associated with the onset of volcanic eruptions or changes in the rates or character of an eruption. Some of these studies have been able to clearly define the cause of the radon anomalies but others have proposed models of radon emission and transport that are not well supported by the known physical and chemical processes that occur in a volcanic system. In order to better characterize the processes that control radon activities in volcanic systems, it is recommended that future radon monitoring programs attempt to maintain continuous recording of radon activities; individual radon measurements should be made over the shortest time intervals possible that are consistent with acceptable counting statistics and geophysical, meteorological, and hydrological parameters should be measured in order to better define the physical processes that affect radon activities in volcanic systems. (author). 63 refs

  9. Slab dehydration in Cascadia and its relationship to volcanism, seismicity, and non-volcanic tremor

    Science.gov (United States)

    Delph, J. R.; Levander, A.; Niu, F.

    2017-12-01

    . Siletzia also contains most of the young arc volcanoes in the Cascades, indicating that water is retained in the slab to depths where it can feed arc volcanism. Thus, the along strike variations in volcanic activity and seismic activity in Cascadia appear to be related to variations in depth of dewatering of the downgoing oceanic lithosphere.

  10. Geothermal and volcanism in west Java

    Science.gov (United States)

    Setiawan, I.; Indarto, S.; Sudarsono; Fauzi I, A.; Yuliyanti, A.; Lintjewas, L.; Alkausar, A.; Jakah

    2018-02-01

    Indonesian active volcanoes extend from Sumatra, Jawa, Bali, Lombok, Flores, North Sulawesi, and Halmahera. The volcanic arc hosts 276 volcanoes with 29 GWe of geothermal resources. Considering a wide distribution of geothermal potency, geothermal research is very important to be carried out especially to tackle high energy demand in Indonesia as an alternative energy sources aside from fossil fuel. Geothermal potency associated with volcanoes-hosted in West Java can be found in the West Java segment of Sunda Arc that is parallel with the subduction. The subduction of Indo-Australian oceanic plate beneath the Eurasian continental plate results in various volcanic products in a wide range of geochemical and mineralogical characteristics. The geochemical and mineralogical characteristics of volcanic and magmatic rocks associated with geothermal systems are ill-defined. Comprehensive study of geochemical signatures, mineralogical properties, and isotopes analysis might lead to the understanding of how large geothermal fields are found in West Java compared to ones in Central and East Java. The result can also provoke some valuable impacts on Java tectonic evolution and can suggest the key information for geothermal exploration enhancement.

  11. Structural control of monogenetic volcanism in the Garrotxa volcanic field (Northeastern Spain) from gravity and self-potential measurements

    Science.gov (United States)

    Barde-Cabusson, S.; Gottsmann, J.; Martí, J.; Bolós, X.; Camacho, A. G.; Geyer, A.; Planagumà, Ll.; Ronchin, E.; Sánchez, A.

    2014-01-01

    We report new geophysical observations on the distribution of subsurface structures associated with monogenetic volcanism in the Garrotxa volcanic field (Northern Spain). As part of the Catalan Volcanic Zone, this Quaternary volcanic field is associated with the European rifts system. It contains the most recent and best preserved volcanic edifices of the Catalan Volcanic Zone with 38 monogenetic volcanoes identified in the Garrotxa Natural Park. We conducted new gravimetric and self-potential surveys to enhance our understanding of the relationship between the local geology and the spatial distribution of the monogenetic volcanoes. The main finding of this study is that the central part of the volcanic field is dominated by a broad negative Bouguer anomaly of around -0.5 mGal, within which a series of gravity minima are found with amplitudes of up to -2.3 mGal. Inverse modelling of the Bouguer data suggests that surficial low-density material dominates the volcanic field, most likely associated with effusive and explosive surface deposits. In contrast, an arcuate cluster of gravity minima to the NW of the Croscat volcano, the youngest volcano of this zone, is modelled by vertically extended low-density bodies, which we interpret as a complex ensemble of fault damage zones and the roots of young scoria cones. A ground-water infiltration zone identified by a self-potential anomaly is associated with a steep horizontal Bouguer gravity gradient and interpreted as a fault zone and/or magmatic fissure, which fed the most recent volcanic activity in the Garrotxa. Gravimetric and self-potential data are well correlated and indicate a control on the locations of scoria cones by NNE-SSW and NNW-SSE striking tectonic features, which intersect the main structural boundaries of the study area to the north and south. Our interpretation of the data is that faults facilitated magma ascent to the surface. Our findings have major implications for understanding the relationship

  12. Mainshock-Aftershocks Clustering Detection in Volcanic Regions

    Science.gov (United States)

    Garza Giron, R.; Brodsky, E. E.; Prejean, S. G.

    2017-12-01

    Crustal earthquakes tend to break their general Poissonean process behavior by gathering into two main kinds of seismic bursts: swarms and mainshock-aftershocks sequences. The former is commonly related to volcanic or geothermal processes whereas the latter is a characteristic feature of tectonically driven seismicity. We explore the mainshock-aftershock clustering behavior of different active volcanic regions in Japan and its comparison to non-volcanic regions. We find that aftershock production in volcanoes shows mainshock-aftershocks clustering similar to what is observed in non-volcanic areas. The ratio of volanic areas that cluster in mainshock-aftershocks sequences vs the areas that do not is comparable to the ratio of non-volcanic regions that show clustering vs the ones that do not. Furthermore, the level of production of aftershocks for most volcanic areas where clustering is present seems to be of the same order of magnitude, or slightly higher, as the median of the non-volcanic regions. An interesting example of highly aftershock-productive volcanoes emerges from the 2000 Miyakejima dike intrusion. A big seismic cluster started to build up rapidly in the south-west flank of Miyakejima to later propagate to the north-west towards the Kozushima and Niijima volcanoes. In Miyakejima the seismicity showed a swarm-like signature with a constant earthquake rate, whereas Kozushima and Niijima both had expressions of highly productive mainshock-aftershocks sequences. These findings are surprising given the alternative mechanisms available in volcanic systems for releasing deviatoric strain. We speculate that aftershock behavior might hold a relationship with the rheological properties of the rocks of each system and with the capacity of a system to accumulate or release the internal pressures caused by magmatic or hydrothermal systems.

  13. Volcanic passive margins: another way to break up continents.

    Science.gov (United States)

    Geoffroy, L; Burov, E B; Werner, P

    2015-10-07

    Two major types of passive margins are recognized, i.e. volcanic and non-volcanic, without proposing distinctive mechanisms for their formation. Volcanic passive margins are associated with the extrusion and intrusion of large volumes of magma, predominantly mafic, and represent distinctive features of Larges Igneous Provinces, in which regional fissural volcanism predates localized syn-magmatic break-up of the lithosphere. In contrast with non-volcanic margins, continentward-dipping detachment faults accommodate crustal necking at both conjugate volcanic margins. These faults root on a two-layer deformed ductile crust that appears to be partly of igneous nature. This lower crust is exhumed up to the bottom of the syn-extension extrusives at the outer parts of the margin. Our numerical modelling suggests that strengthening of deep continental crust during early magmatic stages provokes a divergent flow of the ductile lithosphere away from a central continental block, which becomes thinner with time due to the flow-induced mechanical erosion acting at its base. Crustal-scale faults dipping continentward are rooted over this flowing material, thus isolating micro-continents within the future oceanic domain. Pure-shear type deformation affects the bulk lithosphere at VPMs until continental breakup, and the geometry of the margin is closely related to the dynamics of an active and melting mantle.

  14. Self-potential anomalies preceding tectonic and volcanic crises

    International Nuclear Information System (INIS)

    Patella, D.

    1993-01-01

    In this paper I consider a possible physical mechanism capable of explaining self-potential anomalies, which are currently observed on the ground surface prior to tectonic and volcanic activities. A rock cracking-fluid diffusion-charge polarization model is described. The electrical charge polarization is assumed to be the electrokinetic effect due to invasion of fluid into new fissures, which open inside a stressed rock material because of dilatancy, in the case of tectonic activity, and of the rising of a magma intrusion in the case of volcanic activity. (author). 10 refs, 2 figs

  15. New environmentally-friendly antimicrobials and biocides from Andean and Mexican biodiversity.

    Science.gov (United States)

    Cespedes, Carlos L; Alarcon, Julio; Aqueveque, Pedro M; Lobo, Tatiana; Becerra, Julio; Balbontin, Cristian; Avila, Jose G; Kubo, Isao; Seigler, David S

    2015-10-01

    Persistent application of pesticides often leads to accumulation in the environment and to the development of resistance in various organisms. These chemicals frequently degrade slowly and have the potential to bio-accumulate across the food chain and in top predators. Cancer and neuronal damage at genomic and proteomic levels have been linked to exposure to pesticides in humans. These negative effects encourage search for new sources of biopesticides that are more "environmentally-friendly" to the environment and human health. Many plant or fungal compounds have significant biological activity associated with the presence of secondary metabolites. Plant biotechnology and new molecular methods offer ways to understand regulation and to improve production of secondary metabolites of interest. Naturally occurring crop protection chemicals offer new approaches for pest management by providing new sources of biologically active natural products with biodegradability, low mammalian toxicity and environmentally-friendly qualities. Latin America is one of the world's most biodiverse regions and provide a previously unsuspected reservoir of new and potentially useful molecules. Phytochemicals from a number of families of plants and fungi from the southern Andes and from Mexico have now been evaluated. Andean basidiomycetes are also a great source of scientifically new compounds that are interesting and potentially useful. Use of biopesticides is an important component of integrated pest management (IPM) and can improve the risks and benefits of production of many crops all over the world. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Anthropogenic and volcanic emission impacts on SO2 dynamics and acid rain profiles. Numerical study using WRF-Chem in a high-resolution modeling

    Science.gov (United States)

    Vela, A. V.; González, C. M.; Ynoue, R.; Rojas, N. Y.; Aristizábal, B. H.; Wahl, M.

    2017-12-01

    Eulerian 3-D chemistry transport models (CTM) have been widely used for the study of air quality in urban environments, becoming an essential tool for studying the impacts and dynamics of gases and aerosols on air quality. However, their use in Colombia is scarce, especially in medium-sized cities, which are experimenting a fast urban growth, increasing the risk associated with possible air pollution episodes. In the densely populated medium-sized Andean city of Manizales, Colombia - a city located on the western slopes of the central range of the Andes (urban population 368000; 2150 m.a.s.l), there is an influence of the active Nevado del Ruiz volcano, located 28 km to the southwest. This natural source emits daily gas and particle fluxes, which could influence the atmospheric chemistry of the city and neighboring towns. Hence, the zone presents a unique combination of anthropogenic and volcanic sulfur gas emissions, which affects SO2 dynamics in the urban area, influencing also in the formation of acid rain phenomenon in the city. Therefore, studies analyzing the relative contribution of anthropogenic and volcanic emission could contribute with a deep understanding about causes and dynamics of both acid rain phenomenon and ambient SO2 levels in Manizales. This work aimed to analyze the influence of anthropogenic (on-road vehicular and industrial point-sources) and volcanic sulfur emissions in SO2 atmospheric chemistry dynamics, evaluating its possible effects on acid rain profiles. Ambient SO2 levels and day-night rain samples were measured and used to analyze results obtained from the application of the fully-coupled on-line WRF-Chem model. Two high-resolution simulations were performed during two dry and wet one-week periods in 2015. Analysis of SO2 dispersion patterns and comparison with SO2 observations in the urban area were performed for three different scenarios in which natural and anthropogenic emissions were simulated separately. Results suggest that

  17. Strike-slip pull-apart process and emplacement of Xiangshan uranium-producing volcanic basin

    International Nuclear Information System (INIS)

    Qiu Aijin; Guo Lingzhi; Shu Liangshu

    2001-01-01

    Xiangshan volcanic basin is one of the famous uranium-producing volcanic basins in China. Emplacement mechanism of Xiangshan uranium-producing volcanic basin is discussed on the basis of the latest research achievements of deep geology in Xiangshan area and the theory of continental dynamics. The study shows that volcanic activity in Xiangshan volcanic basin may be divided into two cycles, and its emplacement is controlled by strike-ship pull-apart process originated from the deep regional faults. Volcanic apparatus in the first cycle was emplaced in EW-trending structure activated by clockwise strike-slipping of NE-trending deep fault, forming the EW-trending fissure-type volcanic effusion belt. Volcanic apparatus in the second cycle was emplaced at junction points of SN-trending pull-apart structure activated by sinistral strike-slipping of NE-trending deep faults and EW-trending basement faults causing the center-type volcanic magma effusion and extrusion. Moreover, the formation mechanism of large-rich uranium deposits is discussed as well

  18. Complex land cover change, water and sediment yield in a degraded Andean environment

    Science.gov (United States)

    Molina, Armando; Vanacker, Veerle; Balthazar, Vincent; Mora, Diego; Govers, Gerard

    2012-11-01

    SummaryRapid land use/-cover change has increasingly transformed the hydrological functioning of tropical Andean ecosystems. The hydrological response to forest cover change strongly depends on the initial state of the ecosystem. Relatively little is known about human-disturbed ecosystems where forest plantations have been established on highly degraded land. In this paper, we analyze the impact of forest change on water and sediment fluxes for a highly degraded Andean catchment. Different pathways of land cover change (1963-2007) are observed in the Jadan catchment, with deforestation taking place in remote uplands and recovery and reforestation in the middle and lower parts where agricultural and bare lands are prevalent. Time series analyses of streamflow and rainfall data (1979/1982-2005/2007) show significant shifts in the distribution of rainfall and flow data. Changes in discharge are not resulting from changes in precipitation, as the direction of change is opposite. The removal of native forest for rangeland or croplands (by -20 km2) is likely to have contributed to the increase in total annual water yield, through an increase in annual baseflow by 25 mm. The observed changes in peakflow are important as the 1st percentile highest flow rates were 54% lower, while the 1st percentile rainfall amounts increased by 52%. The observed decrease in peakflow cannot be explained by clearcut of native forest, but is likely to be related to reforestation of degraded lands as well as spontaneous recovery of vegetation on remaining grazing lands. Over the same time period, a major decrease in specific sediment yields and suspended sediment loads was observed. Although deforestation in the upper parts led to increased landslide activity, this change is not reflected in an increased sediment yield. Small upland rivers are often nearly completely blocked by landslide material, thereby reducing their potential to transport sediment. In contrast, the reduction in estimated

  19. Status of volcanism studies for the Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.; Perry, F.; Murrell, M.; Poths, J.; Valentine, G.A. [Los Alamos National Lab., NM (United States); Wells, S. [Univ. of California, Riverside, CA (United States); Bowker, L.; Finnegan, K. [Univ. of Nevada, Las Vegas, NV (United States); Geissman, J.; McFadden, L.

    1995-02-01

    Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. Geophysical data are described for the YMR and are used as an aid to understand the distribution of basaltic volcanic centers. Chapter 4 discusses the petrologic and geochemical features of basaltic volcanism in the YMR, the southern Great Basin and the Basin and Range province. The long time of activity and characteristic small volume of the Postcaldera basalt of the YMR result in one of the lowest eruptive rates in a volcanic field in the southwest United States. Chapter 5 summarizes current concepts of the segregation, ascent, and eruption of basalt magma. Chapter 6 summarizes the history of volcanism studies (1979 through early 1994), including work for the Yucca Mountain Site Characterization Project and overview studies by the state of Nevada and the Nuclear Regulatory Commission. Chapter 7 summarizes probabilistic volcanic hazard assessment using a three-part conditional probability model. Chapter 8 describes remaining volcanism work judged to be needed to complete characterization studies for the YMR. Chapter 9 summarizes the conclusions of this volcanism status report.

  20. Status of volcanism studies for the Yucca Mountain Site Characterization Project

    International Nuclear Information System (INIS)

    Crowe, B.; Perry, F.; Murrell, M.; Poths, J.; Valentine, G.A.; Wells, S.; Bowker, L.; Finnegan, K.; Geissman, J.; McFadden, L.

    1995-02-01

    Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. Geophysical data are described for the YMR and are used as an aid to understand the distribution of basaltic volcanic centers. Chapter 4 discusses the petrologic and geochemical features of basaltic volcanism in the YMR, the southern Great Basin and the Basin and Range province. The long time of activity and characteristic small volume of the Postcaldera basalt of the YMR result in one of the lowest eruptive rates in a volcanic field in the southwest United States. Chapter 5 summarizes current concepts of the segregation, ascent, and eruption of basalt magma. Chapter 6 summarizes the history of volcanism studies (1979 through early 1994), including work for the Yucca Mountain Site Characterization Project and overview studies by the state of Nevada and the Nuclear Regulatory Commission. Chapter 7 summarizes probabilistic volcanic hazard assessment using a three-part conditional probability model. Chapter 8 describes remaining volcanism work judged to be needed to complete characterization studies for the YMR. Chapter 9 summarizes the conclusions of this volcanism status report

  1. Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions

    Science.gov (United States)

    1979-01-01

    This photo of an active volcanic eruption on Jupiter's satellite Io was taken 1 hour, 52 minutes after the accompanying picture, late in the evening of March 4, 1979, Pacific time. On the limb of the satellite can be seen one of at least four simultaneous volcanic eruptions -- the first such activity ever observed on another celestial body. Seen against the limb are plume-like structures rising more than 60 miles (100 kilometers) above the surface. Several eruptions have been identified with volcanic structures on the surface of Io, which have also been identified by Voyager 1's infrared instrument as being abnormally hot -- several hundred degrees warmer than surrounding terrain. The fact that several eruptions appear to be occurring at the same time suggests that Io has the most active surface in the solar system and that volcanism is going on there essentially continuously. Another characteristic of the observed volcanism is that it appears to be extremely explosive, with velocities more than 2,000 miles an hour (at least 1 kilometer per second). That is more violent than terrestrial volcanoes like Etna, Vesuvius or Krakatoa.

  2. Climatic impact of volcanic eruptions

    Science.gov (United States)

    Rampino, Michael R.

    1991-01-01

    Studies have attempted to 'isolate' the volcanic signal in noisy temperature data. This assumes that it is possible to isolate a distinct volcanic signal in a record that may have a combination of forcings (ENSO, solar variability, random fluctuations, volcanism) that all interact. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on temperatures in regions where the effects of aerosol clouds may be amplified by perturbed atmospheric circulation patterns. This is especially true in subpolar and midlatitude areas affected by changes in the position of the polar front. Such climatic perturbation can be detected in proxy evidence such as decrease in tree-ring widths and frost rings, changes in the treeline, weather anomalies, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures. In low latitudes, sudden temperature drops were correlated with the passage overhead of the volcanic dust cloud (Stothers, 1984). For some eruptions, such as Tambora, 1815, these kinds of proxy and anectdotal information were summarized in great detail in a number of papers and books (e.g., Post, 1978; Stothers, 1984; Stommel and Stommel, 1986; C. R. Harrington, in press). These studies lead to the general conclusion that regional effects on climate, sometimes quite severe, may be the major impact of large historical volcanic aerosol clouds.

  3. Changing Hydrology in Glacier-fed High Altitude Andean Peatbogs

    Science.gov (United States)

    Slayback, D. A.; Yager, K.; Baraer, M.; Mohr, K. I.; Argollo, J.; Wigmore, O.; Meneses, R. I.; Mark, B. G.

    2012-12-01

    Montane peatbogs in the glacierized Andean highlands of Peru and Bolivia provide critical forage for camelids (llama and alpaca) in regionally extensive pastoral agriculture systems. During the long dry season, these wetlands often provide the only available green forage. A key question for the future of these peatbog systems, and the livelihoods they support, is the impact of climate change and glacier recession on their hydrology, and thus forage production. We have already documented substantial regional glacier recession, of, on average, approximately 30% of surface area over the past two decades. As glaciers begin to retreat under climate change, there is initially a period of increased meltwater outflow, culminating in a period of "peak water", and followed by a continual decline in outflows. Based on previous work, we know that some glaciers in the region have already passed peak water conditions, and are now declining. To better understand the impacts of these processes on peatbog hydrology and productivity, we have begun collecting a variety of surface data at several study sites in both Bolivia and Peru. These include precipitation, stream flow, water levels, water chemistry and isotope analyses, and peatbog biodiversity and biomass. These measurements will be used in conjunction with a regional model driven by satellite data to predict likely future impacts. We will present the results from these initial surface measurements, and an overview of satellite datasets to be used in the regional model.

  4. Polyhydroxyalkanoate biosynthesis by oxalotrophic bacteria from high Andean soil

    Directory of Open Access Journals (Sweden)

    Roger David Castillo-Arteaga

    2018-02-01

    Full Text Available Oxalate is a highly oxidized organic acid anion used as a carbon and energy source by oxalotrophic bacteria. Oxalogenic plants convert atmospheric CO2 into oxalic acid and oxalic salts. Oxalate-salt formation acts as a carbon sink in terrestrial ecosystems via the oxalate-carbonate pathway (OCP. Oxalotrophic bacteria might be implicated in other carbon-storage processes, including the synthesis of polyhydroxyalkanoates (PHAs. More recently, a variety of bacteria from the Andean region of Colombia in Nariño have been reported for their PHA-producing abilities. These species can degrade oxalate and participate in the oxalate-carbonate pathway. The aim of this study was to isolate and characterize oxalotrophic bacteria with the capacity to accumulate PHA biopolymers. Plants of the genus Oxalis were collected and bacteria were isolated from the soil adhering to the roots. The isolated bacterial strains were characterized using biochemical and molecular biological methods. The consumption of oxalate in culture was quantified, and PHA production was monitored in batch fermentation. The polymeric composition was characterized using gas chromatography. Finally, a biosynthetic pathway based on our findings and on those from published sources is proposed. Strains of Bacillus spp. and Serratia sp. were found to metabolize calcium oxalate and synthesize PHA.

  5. The epidemiology and control of leishmaniasis in Andean countries

    Directory of Open Access Journals (Sweden)

    Davies Clive Richard

    2000-01-01

    Full Text Available This paper reviews the current knowledge of leishmaniasis epidemiology in Venezuela, Colombia, Ecuador, Peru, and Bolivia. In all 5 countries leishmaniasis is endemic in both the Andean highlands and the Amazon basin. The sandfly vectors belong to subgenera Helcocyrtomyia, Nyssomiya, Lutzomyia, and Psychodopygus, and the Verrucarum group. Most human infections are caused by Leishmania in the Viannia subgenus. Human Leishmania infections cause cutaneous lesions, with a minority of L. (Viannia infections leading to mucocutaneous leishmaniasis. Visceral leishmaniasis and diffuse cutaneous leishmaniasis are both rare. In each country a significant proportion of Leishmania transmission is in or around houses, often close to coffee or cacao plantations. Reservoir hosts for domestic transmission cycles are uncertain. The paper first addresses the burden of disease caused by leishmaniasis, focusing on both incidence rates and on the variability in symptoms. Such information should provide a rational basis for prioritizing control resources, and for selecting therapy regimes. Secondly, we describe the variation in transmission ecology, outlining those variables which might affect the prevention strategies. Finally, we look at the current control strategies and review the recent studies on control.

  6. From Subordinate Marker to Discourse Marker: que in Andean Spanish

    Directory of Open Access Journals (Sweden)

    Anna María Escobar

    2005-06-01

    Full Text Available This paper proposes an analysis of a redundant use of que ('that' found in Andean Spanish as an expression which has undergone a grammaticalization process. Evidence suggests that the function of que as subordinate marker is much more generalized in this variety than in other dialects of Spanish. que is found to be used as a marker introducing both nominal and adjectival clauses, suggesting that adjectival subordinates behave as nominal subordinates in this variety of Spanish. An intrusive que appears in restricted syntactic and semantic contexts with clauses that have nominal and adjectival functions, and even appears replacing adverbial expressions in some adverbial subordinates (temporal, spatial, and manner. Furthermore, it is found to be sensitive to the degree of the argument’s thematic/semantic function in the subordinate clause. In particular, it seems to occur more often with low-agency arguments in adjectival and nominal contexts, and, in nominal subordinates, tends to appear with a restricted set of epistemic and evidential main verbs (e.g. creer 'to believe', saber 'to know', decir 'to say'. The analysis suggests that que has developed a new function in this variety of Spanish, namely, one of indicating that the information contained in the subordinate clause does not constitute background information (as would be expected in non-contact varieties of Spanish but instead contains information relevant to the discourse.

  7. Phoretic mites identified on andean hummingbirds (Trochilidae of Caldas, Colombia

    Directory of Open Access Journals (Sweden)

    Natalia López-Orozco

    Full Text Available Within the bird-plant-mite system, the relationship between hummingbirds, flowers, and mites remains poorly understood. In this study, we evaluated the degree of association between nasal mites and eight species of Andean hummingbirds in Colombia (Amazilia saucerrottei,A. tzacatl, Chalybura buffonii,Chlorostilbon mellisugus, Florisuga mellivora, Glaucis hirsutus, Phaethornis guy and P. striigularis. Over a five-month period (trapping effort 360 hours/month, a total of 178 birds were captured, from which 81 mite specimens were collected and identified as belonging to three genera (Proctolaelaps, Rhinoseius andTropicoseius spanning eleven species. This is the first report of its kind from Colombia on the identification of the mite speciesP. rabulatus, R. luteyni, R. rafinskii, T. berryi, T. colwelli, T. erro and T. uniformisand the first record of P. guy as phoretic host forProctolaelaps rabulatus. Morphological characteristics (length of the dorsal plate, width of the dorsal plate and setae z5 length alone failed to distinguish between mite species. The ecologic impact of this relationship on flowers with respect to nectar and pollen availability and the effect of mites on pollination by hummingbirds needs to be determined.

  8. Phoretic mites identified on Andean hummingbirds (Trochilidae) of Caldas, Colombia.

    Science.gov (United States)

    López-Orozco, Natalia; Cañón-Franco, William Alberto

    2013-01-01

    Within the bird-plant-mite system, the relationship between hummingbirds, flowers, and mites remains poorly understood. In this study, we evaluated the degree of association between nasal mites and eight species of Andean hummingbirds in Colombia (Amazilia saucerrottei, A. tzacatl, Chalybura buffonii, Chlorostilbon mellisugus, Florisuga mellivora, Glaucis hirsutus, Phaethornis guy and P. striigularis). Over a five-month period (trapping effort 360 hours/month), a total of 178 birds were captured, from which 81 mite specimens were collected and identified as belonging to three genera (Proctolaelaps, Rhinoseius and Tropicoseius) spanning eleven species. This is the first report of its kind from Colombia on the identification of the mite species P. rabulatus, R. luteyni, R. rafinskii, T. berryi, T. colwelli, T. erro and T. uniformis and the first record of P. guy as phoretic host for Proctolaelaps rabulatus. Morphological characteristics (length of the dorsal plate, width of the dorsal plate and setae z5 length) alone failed to distinguish between mite species. The ecologic impact of this relationship on flowers with respect to nectar and pollen availability and the effect of mites on pollination by hummingbirds needs to be determined.

  9. The epidemiology and control of leishmaniasis in Andean countries

    Directory of Open Access Journals (Sweden)

    Clive Richard Davies

    Full Text Available This paper reviews the current knowledge of leishmaniasis epidemiology in Venezuela, Colombia, Ecuador, Peru, and Bolivia. In all 5 countries leishmaniasis is endemic in both the Andean highlands and the Amazon basin. The sandfly vectors belong to subgenera Helcocyrtomyia, Nyssomiya, Lutzomyia, and Psychodopygus, and the Verrucarum group. Most human infections are caused by Leishmania in the Viannia subgenus. Human Leishmania infections cause cutaneous lesions, with a minority of L. (Viannia infections leading to mucocutaneous leishmaniasis. Visceral leishmaniasis and diffuse cutaneous leishmaniasis are both rare. In each country a significant proportion of Leishmania transmission is in or around houses, often close to coffee or cacao plantations. Reservoir hosts for domestic transmission cycles are uncertain. The paper first addresses the burden of disease caused by leishmaniasis, focusing on both incidence rates and on the variability in symptoms. Such information should provide a rational basis for prioritizing control resources, and for selecting therapy regimes. Secondly, we describe the variation in transmission ecology, outlining those variables which might affect the prevention strategies. Finally, we look at the current control strategies and review the recent studies on control.

  10. Pseudotachylyte formation in volcanic conduits: Montserrat vs. Mount St. Helens

    Science.gov (United States)

    Kendrick, J. E.; Lavallee, Y.; Petrakova, L.; Ferk, A.; Di Toro, G.; Hess, K.; Ferri, F.; Dingwell, D. B.

    2012-12-01

    Seismogenic fracture and faulting may result in non-equilibrium frictional melting of rock, which upon cooling and recrystallisation forms pseudotachylyte. In volcanic environments, the transition from endogenous to exogenous growth can be attributed to a shift in magma rheology into the brittle regime, and thus the ascent of high-viscosity magma can form discrete shear zones, comparable to tectonic faults, along conduit margins. Pseudotachylytes have, until now, rarely been noted in exogenous volcanic materials and seldom in active volcanic environments. This is despite the simultaneous occurrence of high pressures and differential stresses, which make high-viscosity magmas ideal candidates for the occurrence of frictional melting. Here, we compare the chemical, thermal, magnetic and structural properties of two candidate volcanic pseudotachylytes; one from Soufriere Hills (Montserrat) and one from Mount St. Helens (USA). Additionally, we present data from a set of high-velocity rotary shear experiments on the host materials of these natural pseudotachylytes in which melting was induced after just 10's of centimeters of slip at realistic extrusion velocities (0.4 - 1.6 ms-1) and low normal stresses (0.5-2 MPa). After 1-2 meters of slip a continuous melt layer formed, at which point friction decreased and the fault zone displayed slip-weakening behaviour. For volcanic conduits, this would facilitate temporarily elevated slip rates, or an increase in extrusion rate, and could cause transitions in dome morphology and eruption style. This study demonstrates that shear fracturing in magma or sliding along conduit margins can readily result in frictional melting. The conspicuous absence of pseudotachylytes in active volcanic environments is likely the result of exceptionally high background temperatures which precipitate near-equilibrium melting, thereby obviating one of the characteristic signatures of pseudotachylyte - glassy protomelts formed by selective melting of

  11. Preliminary volcanic hazards evaluation for Los Alamos National Laboratory Facilities and Operations : current state of knowledge and proposed path forward

    Energy Technology Data Exchange (ETDEWEB)

    Keating, Gordon N.; Schultz-Fellenz, Emily S.; Miller, Elizabeth D.

    2010-09-01

    The integration of available information on the volcanic history of the region surrounding Los Alamos National Laboratory indicates that the Laboratory is at risk from volcanic hazards. Volcanism in the vicinity of the Laboratory is unlikely within the lifetime of the facility (ca. 50–100 years) but cannot be ruled out. This evaluation provides a preliminary estimate of recurrence rates for volcanic activity. If further assessment of the hazard is deemed beneficial to reduce risk uncertainty, the next step would be to convene a formal probabilistic volcanic hazards assessment.

  12. Use of spatial capture–recapture to estimate density of Andean bears in northern Ecuador

    Science.gov (United States)

    Molina, Santiago; Fuller, Angela K.; Morin, Dana J.; Royle, J. Andrew

    2017-01-01

    The Andean bear (Tremarctos ornatus) is the only extant species of bear in South America and is considered threatened across its range and endangered in Ecuador. Habitat loss and fragmentation is considered a critical threat to the species, and there is a lack of knowledge regarding its distribution and abundance. The species is thought to occur at low densities, making field studies designed to estimate abundance or density challenging. We conducted a pilot camera-trap study to estimate Andean bear density in a recently identified population of Andean bears northwest of Quito, Ecuador, during 2012. We compared 12 candidate spatial capture–recapture models including covariates on encounter probability and density and estimated a density of 7.45 bears/100 km2 within the region. In addition, we estimated that approximately 40 bears used a recently named Andean bear corridor established by the Secretary of Environment, and we produced a density map for this area. Use of a rub-post with vanilla scent attractant allowed us to capture numerous photographs for each event, improving our ability to identify individual bears by unique facial markings. This study provides the first empirically derived density estimate for Andean bears in Ecuador and should provide direction for future landscape-scale studies interested in conservation initiatives requiring spatially explicit estimates of density.

  13. Lost crops of the Incas: Origins of domestication of the Andean pulse crop tarwi, Lupinus mutabilis.

    Science.gov (United States)

    Atchison, Guy W; Nevado, Bruno; Eastwood, Ruth J; Contreras-Ortiz, Natalia; Reynel, Carlos; Madriñán, Santiago; Filatov, Dmitry A; Hughes, Colin E

    2016-09-01

    The Andean highlands are a hotspot of domestication, yet our understanding of the origins of early Andean agriculture remains fragmentary. Key questions of where, when, how many times, and from what progenitors many Andean crops were domesticated remain unanswered. The Andean lupine crop tarwi (Lupinus mutabilis) is a regionally important pulse crop with exceptionally high seed protein and oil content and is the focus of modern breeding efforts, but its origins remain obscure. A large genome-wide DNA polymorphism data set was generated using nextRADseq to infer relationships among more than 200 accessions of Andean Lupinus species, including 24 accessions of L. mutabilis and close relatives. Phylogenetic and demographic analyses were used to identify the likely progenitor of tarwi and elucidate the area and timing of domestication in combination with archaeological evidence. We infer that tarwi was domesticated once in northern Peru, most likely in the Cajamarca region within, or adjacent to the extant distribution of L. piurensis, which is the most likely wild progenitor. Demographic analyses suggest that tarwi split from L. piurensis around 2600 BP and suffered a classical domestication bottleneck. The earliest unequivocal archaeological evidence of domesticated tarwi seeds is from the Mantaro Valley, central Peru ca. 1800 BP. A single origin of tarwi from L. piurensis in northern Peru provides a robust working hypothesis for the domestication of this regionally important crop and is one of the first clear-cut examples of a crop originating in the highlands of northern Peru. © 2016 Botanical Society of America.

  14. The onset of the volcanism in the Ciomadul Volcanic Dome Complex (Eastern Carpathians): Eruption chronology and magma type variation

    Science.gov (United States)

    Molnár, Kata; Harangi, Szabolcs; Lukács, Réka; Dunkl, István; Schmitt, Axel K.; Kiss, Balázs; Garamhegyi, Tamás; Seghedi, Ioan

    2018-04-01

    Combined zircon U-Th-Pb and (U-Th)/He dating was applied to refine the eruption chronology of the last 2 Myr for the andesitic and dacitic Pilişca volcano and Ciomadul Volcanic Dome Complex (CVDC), the youngest volcanic area of the Carpathian-Pannonian region, located in the southernmost Harghita, eastern-central Europe. The proposed eruption ages, which are supported also by the youngest zircon crystallization ages, are much younger than the previously determined K/Ar ages. By dating every known eruption center in the CVDC, repose times between eruptive events were also accurately determined. Eruption of the andesite at Murgul Mare (1865 ± 87 ka) and dacite of the Pilişca volcanic complex (1640 ± 37 ka) terminated an earlier pulse of volcanic activity within the southernmost Harghita region, west of the Olt valley. This was followed by the onset of the volcanism in the CVDC, which occurred after several 100s kyr of eruptive quiescence. At ca. 1 Ma a significant change in the composition of erupted magma occurred from medium-K calc-alkaline compositions to high-K dacitic (Baba-Laposa dome at 942 ± 65 ka) and shoshonitic magmas (Malnaş and Bixad domes; 964 ± 46 ka and 907 ± 66 ka, respectively). Noteworthy, eruptions of magmas with distinct chemical compositions occurred within a restricted area, a few km from one another. These oldest lava domes of the CVDC form a NNE-SSW striking tectonic lineament along the Olt valley. Following a brief (ca. 100 kyr) hiatus, extrusion of high-K andesitic magma continued at Dealul Mare (842 ± 53 ka). After another ca. 200 kyr period of quiescence two high-K dacitic lava domes extruded (Puturosul: 642 ± 44 ka and Balvanyos: 583 ± 30 ka). The Turnul Apor lava extrusion occurred after a ca. 200 kyr repose time (at 344 ± 33 ka), whereas formation of the Haramul Mic lava dome (154 ± 16 ka) represents the onset of the development of the prominent Ciomadul volcano. The accurate determination of eruption dates shows that the

  15. Macrophyte Communities of Andean Rivers: Composition and Relation with Environmental Factors

    Directory of Open Access Journals (Sweden)

    Alida Marcela Gómez Rodríguez

    2017-01-01

    Full Text Available Small streams of tropical Andes have been poorly studied. Therefore, there is little information about the structure, dynamics and function of their macrophyte communities. In this research, aquatic plant communities of 18 Andean streams of La Vieja (Quindío and Otún (Risaralda river basins were studied; those are some of the basins most affected by anthropic activities in the country. Streams were selected according to their association with the main land’s uses of the region in both basins. The aim of the study was to evaluate the effect of land use on the structure of macrophyte communities. Streams running exclusively through each land use were selected. Sampling was done in two different climatic seasons of year 2006. Vegetation found (54 species belonging to 25 families was dominated by species with high capability of adaptation to changing and disturbed environments. Richness and abundance of macrophytes were lower than those reported in other tropical aquatic systems. Variables associated with land use, such as temperature, conductivity and type of substrate of the streams mainly explained the structure of the macrophyte communities: streams running on meat-cattle areas -with higher temperatures, conductivity and dominance of sandy-slimy substrates- had higher macrophyte species richness and abundance than streams of protected-forest areas, with higher coverage by riparian vegetation, lower temperatures and conductivity and rocky substrates.

  16. Insects associated with exposed decomposing bodies in the Colombian Andean Coffee Region

    Directory of Open Access Journals (Sweden)

    Diana Grisales

    2010-01-01

    Full Text Available In Colombia, mainly classic forensic medicine methods were used to clarify crimes until 2004. However, other disciplines, including forensic entomology, started to be considered only after the New Accusatory System introduction in Bogotá and the Coffee Region in 2005. In order to provide tools for obtaining evidentiary material elements in judicial trials, it is presented here the succession of insects throughout the decomposition process of an exposed carcass of Sus scrofa Linnaeus 1758 (Suidae and the Occurrence Matrix of colonizing species. This process was evaluated under ambient conditions in the Andean rural area of the city of Pereira, in the Mundo Nuevo district, located in a pre-montane Wet Forest area, from October to November 2006. A sampling period of 27 days and 3198 individuals were collected. We found these colonizing species in the following stages of decomposition: Lucilia eximia (Wiedemann, 1819 fresh; Hemilucilia semidiaphana (Rondani, 1850, Oxelytrum discicolle (Brullé, 1840, and Cochliomyia macellaria (Fabricius 1775 bloated; Chrysomya albiceps (Wiedemann 1819, Compsomyiops verena (Walker, 1849, Ophyra aenescens (Wiedemann, 1830 and Musca domestica Linnaeus, 1758 active; Fannia sp. advanced and Stearibia nigriceps (Meigen, 1826 remains. This study provides support tools to define the Post Mortem Interval that may be used by experts from government institutions and laboratories officially accredited.

  17. [Floristic composition and distribution of the Andean subtropical riparian forests of Lules River, Tucuman, Argentina].

    Science.gov (United States)

    Sirombra, Martín G; Mesa, Leticia M

    2010-03-01

    We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem.

  18. Global volcanic aerosol properties derived from emissions, 1990-2014, using CESM1(WACCM): VOLCANIC AEROSOLS DERIVED FROM EMISSIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Michael J. [Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder Colorado USA; Schmidt, Anja [School of Earth and Environment, University of Leeds, Leeds UK; Easter, Richard [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Solomon, Susan [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge Massachusetts USA; Kinnison, Douglas E. [Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder Colorado USA; Ghan, Steven J. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Neely, Ryan R. [School of Earth and Environment, University of Leeds, Leeds UK; National Centre for Atmospheric Science, University of Leeds, Leeds UK; Marsh, Daniel R. [Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder Colorado USA; Conley, Andrew [Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder Colorado USA; Bardeen, Charles G. [Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder Colorado USA; Gettelman, Andrew [Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder Colorado USA

    2016-03-06

    Accurate representation of global stratospheric aerosol properties from volcanic and non-volcanic sulfur emissions is key to understanding the cooling effects and ozone-loss enhancements of recent volcanic activity. Attribution of climate and ozone variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the apparent rate of global average temperature increases, and variable recovery of the Antarctic ozone hole. We have developed a climatology of global aerosol properties from 1990 to 2014 calculated based on volcanic and non-volcanic emissions of sulfur sources. We have complied a database of volcanic SO2 emissions and plume altitudes for eruptions between 1990 and 2014, and a new prognostic capability for simulating stratospheric sulfate aerosols in version 5 of the Whole Atmosphere Community Climate Model, a component of the Community Earth System Model. Our climatology shows remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD), and with in situ measurements of aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD climatology represents a significant improvement over satellite-based analyses, which ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at mid- and high-latitudes. Our SAD climatology significantly improves on that provided for the Chemistry-Climate Model Initiative, which misses 60% of the SAD measured in situ. Our climatology of aerosol properties is publicly available on the Earth System Grid.

  19. Volcanic systems of Iceland and their magma source

    Science.gov (United States)

    Sigmarsson, Olgeir

    2017-04-01

    Several active hot-spot volcanoes produce magma from mantle sources which composition varies on decadal time scale. This is probably best demonstrated by the recent work of Pietruszka and collaborators on Kilauea, Hawaii. In marked contrast, basalt lavas from volcanic system in Iceland located above the presumed centre of the Iceland mantle plume have uniform isotope composition over the last 10 thousand years. Volcanic systems are composed of a central volcano and a fissure swarm, or a combination of both and they represent a fundamental component of the neovolcanic zones in Iceland. Four such systems, those of Askja, Bárðarbunga, Kverkfjöll and Grímsvötn in central Iceland were chosen for investigation. The last three have central volcanoes covered by the Vatnajökull ice-sheet whereas part of their fissure swarms is ice-free. Tephra produced during subglacial eruptions together with lavas from the fissure swarms of Holocene age have been collected and analysed for Sr, Nd and Th isotope ratios. Those volcanic formations that can be univocally correlated to a given volcanic system display uniform isotope ratio but different from one volcanic system to another. An exception to this regularity is that Askja products have isotope ratios indistinguishable from those of Gímsvötn, but since these volcanic systems lies far apart their lava fields do not overlap. A practical aspect of these findings was demonstrated during the rifting event of Bárðarbunga and fissure eruption forming the Holuhraun lava field. Relatively low, O isotope ratios in these basalts and heterogeneous macrocrystal composition have been ascribed to important metabasaltic crustal contamination with or without crystal mush recycling. In that case a surprisingly efficient magma mixing and melt homogenization must have occurred in the past beneath the volcanic systems. One possibility is that during the rapid deglaciation much mantle melting occurred and melts accumulated at the mantle

  20. Volcanic influence on centennial to millennial Holocene Greenland temperature change.

    Science.gov (United States)

    Kobashi, Takuro; Menviel, Laurie; Jeltsch-Thömmes, Aurich; Vinther, Bo M; Box, Jason E; Muscheler, Raimund; Nakaegawa, Toshiyuki; Pfister, Patrik L; Döring, Michael; Leuenberger, Markus; Wanner, Heinz; Ohmura, Atsumu

    2017-05-03

    Solar variability has been hypothesized to be a major driver of North Atlantic millennial-scale climate variations through the Holocene along with orbitally induced insolation change. However, another important climate driver, volcanic forcing has generally been underestimated prior to the past 2,500 years partly owing to the lack of proper proxy temperature records. Here, we reconstruct seasonally unbiased and physically constrained Greenland Summit temperatures over the Holocene using argon and nitrogen isotopes within trapped air in a Greenland ice core (GISP2). We show that a series of volcanic eruptions through the Holocene played an important role in driving centennial to millennial-scale temperature changes in Greenland. The reconstructed Greenland temperature exhibits significant millennial correlations with K + and Na + ions in the GISP2 ice core (proxies for atmospheric circulation patterns), and δ 18 O of Oman and Chinese Dongge cave stalagmites (proxies for monsoon activity), indicating that the reconstructed temperature contains hemispheric signals. Climate model simulations forced with the volcanic forcing further suggest that a series of large volcanic eruptions induced hemispheric-wide centennial to millennial-scale variability through ocean/sea-ice feedbacks. Therefore, we conclude that volcanic activity played a critical role in driving centennial to millennial-scale Holocene temperature variability in Greenland and likely beyond.

  1. Seed production differences of the Andean oak Quercus Humboldtii Bonpl. in two Andean forests of the Colombian Eastern Cordillera

    International Nuclear Information System (INIS)

    Gonzalez Melo, Andres; Parrado Rosselli Angela

    2010-01-01

    Knowledge of mechanisms of tree species reproduction under natural situations including fruit and seed production patterns is very important for forest management strategies. Considering the influence of abiotic factors such as soil characteristics, humidity and rainfall on fruiting phenology, we studied fruit production patterns of the Andean oak (Quercus humboldtii: Fagaceae) in two forest sites of the Colombian Eastern Cordillera (Cachalu and Patios Altos), under contrasting environmental conditions. At both sites, we monitored monthly fruit production of 15 trees in Cachalu and 11 in Patios Altos using fruit/seed traps placed under the tree crowns. In each site soil cores were extracted below the litter layer 20 cm depth, and soil characteristics and nutrients were analyzed. In general, trees in Cachalu produced more fruits than in Patios Altos, as well as mean fruit mass (wet and dry weight) was significantly higher in Cachalu. At both sites, oak fruiting peaked from April to May, when the highest rainfall occurs. We found positive correlations between fruit production and rainfall one month prior. High phosphorus (P) and potassium (K) were the main variables for explaining the high production. In contrast, high aluminum (Al) contents explained the low production found in Patios Altos. We discuss the importance of including fruit production for oak management strategies, such as restoration and reforestation programs.

  2. Effects of heat-flow and hydrothermal fluids from volcanic intrusions on authigenic mineralization in sandstone formations

    Directory of Open Access Journals (Sweden)

    Wolela Ahmed

    2002-06-01

    Full Text Available Volcanic intrusions and hydrothermal activity have modified the diagenetic minerals. In the Ulster Basin, UK, most of the authigenic mineralization in the Permo-Triassic sandstones pre-dated tertiary volcanic intrusions. The hydrothermal fluids and heat-flow from the volcanic intrusions did not affect quartz and feldspar overgrowths. However, clay mineral-transformation, illite-smectite to illite and chlorite was documented near the volcanic intrusions. Abundant actinolite, illite, chlorite, albite and laumontite cementation of the sand grains were also documented near the volcanic intrusions. The abundance of these cementing minerals decreases away from the volcanic intrusions.In the Hartford Basin, USA, the emplacement of the volcanic intrusions took place simultaneous with sedimentation. The heat-flow from the volcanic intrusions and hydrothermal activity related to the volcanics modified the texture of authigenic minerals. Microcrystalline mosaic albite and quartz developed rather than overgrowths and crystals near the intrusions. Chlorite clumps and masses were also documented with microcrystalline mosaic albite and quartz. These features are localized near the basaltic intrusions. Laumontite is also documented near the volcanic intrusions. The reservoir characteristics of the studied sandstone formations are highly affected by the volcanic and hydrothermal fluids in the Hartford and the Ulster Basin. The porosity dropped from 27.4 to zero percent and permeability from 1350 mD to 1 mD.

  3. Thermal effects of massive CO2 emissions associated with subduction volcanism

    NARCIS (Netherlands)

    Schuiling, R.D.

    2004-01-01

    Large volumes of CO₂ are emitted during volcanic activity at convergent plate boundaries, not only from volcanic centers. Their C isotopic signature indicates that this CO₂ is mainly derived from the decarbonation of subducted limestones or carbonated metabasalts, not as often admitted from magma

  4. The volcanic and geochemical development of São Nicolau, Cape Verde Islands

    DEFF Research Database (Denmark)

    Duprat, Helene Inga; Holm, Paul Martin; Sherson, Jacob Friis

    2007-01-01

    We present 34 new age results from 40 Ar/39 Ar incremental heating analyses of groundmass separates from volcanic rocks from São Nicolau, Cape Verde. Combining the age results with field observations, we show that the volcanic activity that formed the island occurred in four separate stages: 1: >6...

  5. Records of climatic changes and volcanic events in an ice core from ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    the volcanic event that occurred in 1815 AD, has been identified based on electrical conductance ... tions and accumulation rates of ice, climatic and ..... The peak saturated values of currents (µ amp) at about 5 and 30m depths identify the past volcanic episodes Augung ..... in promoting the scientific activities by allowing us.

  6. Geophysical imaging of buried volcanic structures within a continental back-arc basin

    DEFF Research Database (Denmark)

    Stratford, Wanda Rose; Stern, T.A.

    2008-01-01

    Hidden beneath the ~2 km thick low-velocity volcaniclastics on the western margin of the Central Volcanic Region, North Island, New Zealand, are two structures that represent the early history of volcanic activity in a continental back-arc. These ~20×20 km structures, at Tokoroa and Mangakino, fo...

  7. Mud volcanism of South-Caspian depression

    International Nuclear Information System (INIS)

    Aliyev, A.A.

    2002-01-01

    Full text : South-Caspian depression is presented by area of large warping with thick (more than 25 km) sedimentary series and with wide development of mud volcanism. This depression is unique according to its number of mud volcanoes and intensity of their eruptions. There are about 400 mud volcanoes in this area, which is more than than a half of all volcanoes of the planet. Among them - 220 are continental, more 170 are marine, defined by different methods in the South-Caspian aquatorium. As a result of mudvolcanic activity islands, banks, shoals and underwater ridges are formed in marine conditions. Depths of underwater volcanoes vary from few meters to 900 m as the height of cones are different too. Marine mud volcanoes in geological history of Caspian sea evolution and in its recent history had and important significance. Activity of mud volcanoes in sea conditions lead to the formation of positive elements of relief. Products of ejection take part in the formation of microrelief of surrounding areas of sea bottom influence upon its dynamics and composition of bottom sediments. The carried out comparative analysis of mud volcanism manifestation both onshore and offshore showed the basic differences and similarities in morphology of volcanoes and geology-geochemical peculiarities of eruption products. New data on tectonics of mud volcanism development has been obtained over recent years. Mud volcanoes of South-Caspian depression are studied for assessment and oil-gas content of deep-seated deposits. Geochemical method of search of oil and gas deposits in mudvolcanic areas had been worked out.

  8. The origin and crust/mantle mass balance of Central Andean ignimbrite magmatism constrained by oxygen and strontium isotopes and erupted volumes

    Science.gov (United States)

    Freymuth, Heye; Brandmeier, Melanie; Wörner, Gerhard

    2015-06-01

    Volcanism during the Neogene in the Central Volcanic Zone (CVZ) of the Andes produced (1) stratovolcanoes, (2) rhyodacitic to rhyolitic ignimbrites which reach volumes of generally less than 300 km3 and (3) large-volume monotonous dacitic ignimbrites of up to several thousand cubic kilometres. We present models for the origin of these magma types using O and Sr isotopes to constrain crust/mantle proportions for the large-volume ignimbrites and explore the relationship to the evolution of the Andean crust. Oxygen isotope ratios were measured on phenocrysts in order to avoid the effects of secondary alteration. Our results show a complete overlap in the Sr-O isotope compositions of lavas from stratovolcanoes and low-volume rhyolitic ignimbrites as well as older (>9 Ma) large-volume dacitic ignimbrites. This suggests that the mass balance of crustal and mantle components are largely similar. By contrast, younger (estimated the volume of these ignimbrite deposits throughout the Central Andes during the Neogene and examined the spatiotemporal pattern of so-called ignimbrite flare-ups. We observe a N-S migration of maximum ages of the onset of large-volume "ignimbrite pulses" through time: Major pulses occurred at 19-24 Ma (e.g. Oxaya, Nazca Group), 13-14 Ma (e.g. Huaylillas and Altos de Pica ignimbrites) and 70 km3 Ma-1 km-1 (assuming plutonic/volcanic ratios of 1:5) which are additional to, but within the order of, the arc background magmatic flux. Comparing our results to average shortening rates observed in the Andes, we observe a "lag-time" with large-volume eruptions occurring after accelerated shortening. A similar delay exists between the ignimbrite pulses and the subduction of the Juan Fernandez ridge. This is consistent with the idea that large-volume ignimbrite eruptions occurred in the wake of the N-S passage of the ridge after slab steepening has allowed hot asthenospheric mantle to ascend into and cause the melting of the mantle wedge. In our model, the

  9. Critical review of a new volcanic eruption chronology

    Science.gov (United States)

    Neuhäuser, Dagmar L.; Neuhäuser, Ralph

    2016-04-01

    Sigl. et al. (2015, Nature) present historical evidence for 32 volcanic eruptions to evaluate their new polar ice core 10-Be chronology - 24 are dated within three years of sulfur layers in polar ice. Most of them can be interpreted as weather phenomena (Babylonia: disk of sun like moon, reported for only one day, e.g. extinction due to clouds), Chinese sunspot reports (pellet, black vapor, etc.), solar eclipses, normal ice-halos and coronae (ring, bow, etc.), one aurora (redness), red suns due to mist drops in wet fog or fire-smoke, etc. Volcanic dust may facilitate detections of sunspots and formation of Bishop's ring, but tend to inhibit ice-halos, which are otherwise often reported in chronicles. We are left with three reports possibly indicating volcanic eruptions, namely fulfilling genuine criteria for atmospheric disturbances due to volcanic dust, e.g. bluish or faint sun, orange sky, or fainting of stars for months (BCE 208, 44-42, and 32). Among the volcanic eruptions used to fix the chronology (CE 536, 626, 939, 1257), the reports cited for the 930s deal only with 1-2 days, at least one reports an eclipse. In the new chronology, there is a sulfur detection eight years after the Vesuvius eruption, but none in CE 79. It may appear surprising that, from BCE 500 to 1, all five northern sulfur peaks labeled in figure 2 in Sigl et al. are systematically later by 2-4 years than the (corresponding?) southern peaks, while all five southern peaks from CE 100 to 600 labeled in figure 2 are systematically later by 1-4 years than the (corresponding?) northern peaks. Furthermore, in most of their six strongest volcanic eruptions, temperatures decreased years before their sulfur dating - correlated with weak solar activity as seen in radiocarbon, so that volcanic climate forcing appears dubious here. Also, their 10-Be peaks at CE 775 and 994 are neither significant nor certain in dating.

  10. Candidate constructional volcanic edifices on Mercury

    OpenAIRE

    Wright, J.; Rothery, D. A.; Balme, M. R.; Conway, S. J.

    2018-01-01

    [Introduction] Studies using MESSENGER data suggest that Mercury’s crust is predominantly a product of effusive volcanism that occurred in the first billion years following the planet’s formation. Despite this planet-wide effusive volcanism, no constructional volcanic edifices, characterized by a topographic rise, have hitherto been robustly identified on Mercury, whereas constructional volcanoes are common on other planetary bodies in the solar system with volcanic histories. Here, we descri...

  11. The monogenetic Bayuda Volcanic Field, Sudan - New insights into geology and volcanic morphology

    Science.gov (United States)

    Lenhardt, Nils; Borah, Suranjana B.; Lenhardt, Sukanya Z.; Bumby, Adam J.; Ibinoof, Montasir A.; Salih, Salih A.

    2018-05-01

    The small monogenetic Bayuda Volcanic Field (BVF; 480 km2), comprising at least 53 cinder cones and 15 maar volcanoes in the Bayuda desert of northern Sudan is one of a few barely studied volcanic occurrences of Quaternary age in Sudan. The exact age of the BVF and the duration of volcanic activity has not yet been determined. Furthermore, not much is known about the eruptional mechanisms and the related magmatic and tectonic processes that led to the formation of the volcanic field. In the framework of a larger project focusing on these points it is the purpose of this contribution to provide a first account of the general geology of the BVF volcanoes as well as a first description of a general stratigraphy, including a first description of their morphological characteristics. This was done by means of fieldwork, including detailed rock descriptions, as well as the analysis of satellite images (SRTM dataset at 30 m spatial resolution). The BVF cinder cones are dominated by scoracious lapilli tephra units, emplaced mainly by pyroclastic fallout from Strombolian eruptions. Many cones are breached and are associated with lava flows. The subordinate phreatomagmatism represented by maar volcanoes suggests the presence of ground and/or shallow surface water during some of the eruptions. The deposits constituting the rims around the maar volcanoes are interpreted as having mostly formed due to pyroclastic surges. Many of the tephra rings around the maars are underlain by thick older lava flows. These are inferred to be the horizons where rising magma interacted with groundwater. The existence of phreatomagmatic deposits may point to a time of eruptive activity during a phase with wetter conditions and therefore higher groundwater levels than those encountered historically. This is supported by field observations as well as the morphological analysis, providing evidence for relatively high degrees of alteration of the BVF volcanoes and therefore older eruption ages as

  12. Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation

    Science.gov (United States)

    Praetorius, Summer; Mix, Alan; Jensen, Britta; Froese, Duane; Milne, Glenn A.; Wolhowe, Matthew; Addison, Jason A.; Prahl, Fred

    2016-01-01

    Observations of enhanced volcanic frequency during the last deglaciation have led to the hypothesis that ice unloading in glaciated volcanic terrains can promote volcanism through decompression melting in the shallow mantle or a reduction in crustal magma storage time. However, a direct link between regional climate change, isostatic adjustment, and the initiation of volcanism remains to be demonstrated due to the difficulty of obtaining high-resolution well-dated records that capture short-term climate and volcanic variability traced to a particular source region. Here we present an exceptionally resolved record of 19 tephra layers paired with foraminiferal oxygen isotopes and alkenone paleotemperatures from marine sediment cores along the Southeast Alaska margin spanning the last deglacial transition. Major element compositions of the tephras indicate a predominant source from the nearby Mt. Edgecumbe Volcanic Field (MEVF). We constrain the timing of this regional eruptive sequence to 14.6–13.1 ka. The sudden increase in volcanic activity from the MEVF coincides with the onset of Bølling–Allerød interstadial warmth, the disappearance of ice-rafted detritus, and rapid vertical land motion associated with modeled regional isostatic rebound in response to glacier retreat. These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity. Rapid sea surface temperature fluctuations and an increase in local salinity (i.e., δ18Osw) variability are associated with the interval of intense volcanic activity, consistent with a two-way interaction between climate and volcanism in which rapid volcanic response to ice unloading may in turn enhance short-term melting of the glaciers, plausibly via albedo effects on glacier ablation zones.

  13. Volcanism on differentiated asteroids (Invited)

    Science.gov (United States)

    Wilson, L.

    2013-12-01

    The Dawn spacecraft's investigation of 4 Vesta, best-preserved of the early-forming differentiated asteroids, prompts a reappraisal of factors controlling igneous activity on such bodies. Analogy with melt transfer in zones of partial melting on Earth implies that silicate melts moved efficiently within asteroid mantles in complex networks of veins and dikes, so that only a few percent of the mantle consisted of melt at any one time. Thus even in cases where large amounts of mantle melting occurred, the melts did not remain in the mantle to form "magma oceans", but instead migrated to shallow depths. The link between magma flow rate and the stresses needed to keep fractures open and allow flow fast enough to avoid excessive cooling implies that only within asteroids with radii more than ~190-250 km would continuous magma flow from mantle to surface be possible. In all smaller asteroids (including Vesta) magma must have accumulated in sills at the base of the lithosphere (the conductively controlled ~10 km thick thermal boundary layer) or in crustal magma reservoirs near its base. Magma would then have erupted intermittently to the surface from these steadily replenished reservoirs. The average rates of eruption to the surface (or shallow intrusion) should balance the magma production rate, but since magma could accumulate and erupt intermittently from these reservoirs, the instantaneous eruption rates could be hundreds to thousands of cubic m/s, comparable to historic basaltic eruption rates on Earth and very much greater than the average mantle melting rate. The absence of asteroid atmospheres makes explosive eruptions likely even if magmas are volatile-poor. On asteroids with radii less than ~100 km, gases and sub-mm pyroclastic melt droplets would have had speeds exceeding the escape speed assuming a few hundred ppm volatiles, and only cm sized or larger clasts would have been retained. On larger bodies almost all pyroclasts will have returned to the surface

  14. Principal geological characteristics of the volcanic-type uranium deposits in China

    International Nuclear Information System (INIS)

    Fang Xiheng

    2009-01-01

    The volcanic-type uranium deposits in China distribute in two gigantic active belts, that is, circum-Pacific belt and latitudinal structure belt crossing Europe-Asia. The volcanic-type uranium deposits occur in continental volcanics,which are mainly composed of acid or alkali volcanics. Based on the study of 87 Sr/ 86 Sr initial ratio, REE distribution pattern and melt inclusion thermometry of volcanics, it is found that volcanic magma originated mainly from high-temperature melt of sialsphere and they were propably contaiminated partially by mantle materials. The volcanic eruption was controlled by regional fault and formed eruption belt, the beld can be divided into several sub-belt which was comprised by a serial eruption centres. The volcanic-type uranium deposits occur by the side of down-faulted red basin or associated with basic swarm. This means that the uranium mineralization is related to deep tectonics-magmatism. The paper proposes that the moderate erosion of volcanic belt is an important precondition to find uranium deposits. (authors)

  15. Properties of volcanic soils in cold climate conditions

    Science.gov (United States)

    Kuznetsova, Elena

    2017-04-01

    Layers of volcanic ash and the Andosol soils derived from them may play an important role in preserving snow and ice as well as developing permafrost conditions in the immediate vicinity of volcanoes of high elevation or those situated at high latitudes, and land areas, often distant from volcanic activity that are either prone to permafrost or covered by snow and ice, but are affected by the deposition of subaerial ash. The special properties of volcanic ash that are responsible are critically reviewed particularly in relation to recent research in Kamchatka in the Far East of Russia. Of particular importance are the thermal properties and the unfrozen water contents of ash layers and the rate at which the weathering of volcanic glass takes place. Volcanic glass is the most easily weathered component of volcanic ejecta (Shoji et al., 1993; Kimble et al., 2000). There are many specific environmental conditions, including paleoclimate and present-day climate, the composition of volcanic tephra and glaciation history, which cause the differences in weathering and development of volcanic ash soils (Zehetner et al., 2003). The preservation of in situ, unweathered, and unaltered surficial ash-fall deposits in the cold regions has important implications for paleoclimate and glacial history. Ash-fall deposits, which trap and preserve the soils, sediments, and landforms on which they fall, can be used to resolve local climate conditions (temperature and moisture) at the ash site during ash-fall deposition. The preservation of detailed sedimentary features (e.g. bedding in the ash, sharpness of stratigraphic contacts) can tell us about their post-depositional history, whether they have been redeposited by wind or water, or overridden by glaciers (Marchant et al., 1996). Weathering of volcanic glass results in the development of amorphous clay minerals (e.g. allophane, opal, palagonite) but this takes place much slower in cold than under warmer climate conditions. Only few

  16. [Structural recovering in Andean successional forests from Porce (Antioquia, Colombia)].

    Science.gov (United States)

    Yepes, Adriana P; del Valle, Jorge I; Jaramillo, Sandra L; Orrego, Sergio A

    2010-03-01

    Places subjected to natural or human disturbance can recover forest through an ecological process called secondary succession. Tropical succession is affected by factors such as disturbances, distance from original forest, surface configuration and local climate. These factors determine the composition of species and the time trend of the succession itself. We studied succession in soils used for cattle ranching over various decades in the Porce Region of Colombia (Andean Colombian forests). A set of twenty five permanent plots was measured, including nine plots (20 x 50 m) in primary forests and sixteen (20 x 25 m) in secondary forests. All trees with diameter > or =1.0 cm were measured. We analyzed stem density, basal area, above-ground biomass and species richness, in a successional process of ca. 43 years, and in primary forests. The secondary forests' age was estimated in previous studies, using radiocarbon dating, aerial photographs and a high-resolution satellite image analysis (7 to >43 years). In total, 1,143 and 1,766 stems were measured in primary and secondary forests, respectively. Basal area (5.7 to 85.4 m2 ha(-1)), above-ground biomass (19.1 to 1,011.5 t ha(-1)) and species richness (4 to 69) directly increased with site age, while steam density decreased (3,180 to 590). Diametric distributions were "J-inverted" for primary forests and even-aged size-class structures for secondary forests. Three species of palms were abundant and exclusive in old secondary forests and primary forests: Oenocarpus mapora, Euterpe precatoria and Oenocarpus bataua. These palms happened in cohorts after forest disturbances. Secondary forest structure was 40% in more than 43 years of forest succession and indicate that many factors are interacting and affecting the forests succession in the area (e.g. agriculture, cattle ranching, mining, etc.).

  17. Social inequality and child malnutrition in four Andean countries.

    Science.gov (United States)

    Larrea, Carlos; Freire, Wilma

    2002-01-01

    To analyze the effects of socioeconomic, regional, and ethnic conditions on chronic malnutrition in four Andean countries of South America: Bolivia, Colombia, Ecuador, and Peru. The study was based on Demographic and Health Surveys (DHS) for Colombia (1995), Peru (1996), and Bolivia (1997), and on a Living Standard Measurement Survey for Ecuador (1998). We developed an index of household socioeconomic status using categorical principal components analysis. We broke down the prevalence of stunting by socioeconomic status (SES), ethnicity, place of residence (large cities, small cities, towns, and countryside), and region (highland region versus other areas of the country). We applied smoothed regression curves and linear functions to analyze SES effects on stunting, with specific models for Bolivia, Ecuador, and Peru. Bolivia, Ecuador, and Peru have similar characteristics, with high stunting prevalences overall; higher stunting prevalences in their highland areas, particularly among indigenous populations; and strong socioeconomic disparities. Colombia, in contrast, has a lower stunting prevalence and smaller regional disparities. The socioeconomic gradient of stunting is strong in all four countries, with prevalence rates in the poorest deciles at least three times as high as those in the top decile. The sharp contrast between the conditions found in Bolivia, Ecuador, and Peru and those in Colombia may be the result of specific ethnic factors affecting indigenous groups; a particular diet profile in the highland areas, with low protein and micronutrient intake; and differences in the long-term economic and social development paths that the countries have taken. Along with the strong socioeconomic gradient in all the countries, the weight of ethnic and regional factors suggests the need to reduce inequality as well as to comprehensively improve education and housing, better target health and nutrition programs, and implement participatory programs integrated into

  18. Social inequality and child malnutrition in four Andean countries

    Directory of Open Access Journals (Sweden)

    Carlos Larrea

    2002-06-01

    Full Text Available Objective. To analyze the effects of socioeconomic, regional, and ethnic conditions on chronic malnutrition in four Andean countries of South America: Bolivia, Colombia, Ecuador, and Peru. Methods. The study was based on Demographic and Health Surveys (DHS for Colombia (1995, Peru (1996, and Bolivia (1997, and on a Living Standard Measurement Survey for Ecuador (1998. We developed an index of household socioeconomic status using categorical principal components analysis. We broke down the prevalence of stunting by socioeconomic status (SES, ethnicity, place of residence (large cities, small cities, towns, and countryside, and region (highland region versus other areas of the country. We applied smoothed regression curves and linear functions to analyze SES effects on stunting, with specific models for Bolivia, Ecuador, and Peru. Results. Bolivia, Ecuador, and Peru have similar characteristics, with high stunting prevalences overall; higher stunting prevalences in their highland areas, particularly among indigenous populations; and strong socioeconomic disparities. Colombia, in contrast, has a lower stunting prevalence and smaller regional disparities. The socioeconomic gradient of stunting is strong in all four countries, with prevalence rates in the poorest deciles at least three times as high as those in the top decile. Discussion. The sharp contrast between the conditions found in Bolivia, Ecuador, and Peru and those in Colombia may be the result of specific ethnic factors affecting indigenous groups; a particular diet profile in the highland areas, with low protein and micronutrient intake; and differences in the long-term economic and social development paths that the countries have taken. Along with the strong socioeconomic gradient in all the countries, the weight of ethnic and regional factors suggests the need to reduce inequality as well as to comprehensively improve education and housing, better target health and nutrition programs

  19. Diverging responses of tropical Andean biomes under future climate conditions.

    Directory of Open Access Journals (Sweden)

    Carolina Tovar

    Full Text Available Observations and projections for mountain regions show a strong tendency towards upslope displacement of their biomes under future climate conditions. Because of their climatic and topographic heterogeneity, a more complex response is expected for biodiversity hotspots such as tropical mountain regions. This study analyzes potential changes in the distribution of biomes in the Tropical Andes and identifies target areas for conservation. Biome distribution models were developed using logistic regressions. These models were then coupled to an ensemble of 8 global climate models to project future distribution of the Andean biomes and their uncertainties. We analysed projected changes in extent and elevational range and identified regions most prone to change. Our results show a heterogeneous response to climate change. Although the wetter biomes exhibit an upslope displacement of both the upper and the lower boundaries as expected, most dry biomes tend to show downslope expansion. Despite important losses being projected for several biomes, projections suggest that between 74.8% and 83.1% of the current total Tropical Andes will remain stable, depending on the emission scenario and time horizon. Between 3.3% and 7.6% of the study area is projected to change, mostly towards an increase in vertical structure. For the remaining area (13.1%-17.4%, there is no agreement between model projections. These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions. Instead, our models project diverging responses, including downslope expansion and large areas projected to remain stable. Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management. This, and the inclusion of a comprehensive uncertainty analysis, will help to inform conservation strategies in the Tropical Andes, and to guide similar

  20. A Volcanic Hydrogen Habitable Zone

    International Nuclear Information System (INIS)

    Ramirez, Ramses M.; Kaltenegger, Lisa

    2017-01-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N_2–CO_2–H_2O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO_2 outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H_2 can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N_2–CO_2–H_2O–H_2) can be sustained as long as volcanic H_2 output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H_2 warming is reduced in dense H_2O atmospheres. The atmospheric scale heights of such volcanic H_2 atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.

  1. A Volcanic Hydrogen Habitable Zone

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Ramses M.; Kaltenegger, Lisa, E-mail: rmr277@cornell.edu [Carl Sagan Institute, Cornell University, Ithaca, NY (United States)

    2017-03-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N{sub 2}–CO{sub 2}–H{sub 2}O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO{sub 2} outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H{sub 2} can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N{sub 2}–CO{sub 2}–H{sub 2}O–H{sub 2}) can be sustained as long as volcanic H{sub 2} output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H{sub 2} warming is reduced in dense H{sub 2}O atmospheres. The atmospheric scale heights of such volcanic H{sub 2} atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.

  2. Glacial recession in the Tropical Andes from the Little Ice Age: the case of Ampato Volcanic Complex (Southern Peru

    Science.gov (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.

    2010-03-01

    . Annals of Glaciology, 50. Stern, C. R. (2004): Active Andean volcanism: it’s geologic and tectonic setting. Revista Geológica de Chile, 31: 161-206. Úbeda, J., Palacios D., Vazquez L. (2009 a) Reconstruction of Equilibrium Line Altitudes of Nevado Coropuna Glaciers (Southern Peru) from the Late Pleistocene to the present. Geophysical Research Abstracts, 11, EGU2009-8067-2, Vuille, M.; Francou, B.; Wagnon, P.; Juen, I. ; Kaser, G. ; Mark, B. ; y Bradley, R. (2008) : Climate change and tropical Andean glaciers : Past, present and future. Earth-Science Reviews, 89: 79-96.

  3. Lahar—River of volcanic mud and debris

    Science.gov (United States)

    Major, Jon J.; Pierson, Thomas C.; Vallance, James W.

    2018-05-09

    Lahar, an Indonesian word for volcanic mudflow, is a mixture of water, mud, and volcanic rock flowing swiftly along a channel draining a volcano. Lahars can form during or after eruptions, or even during periods of inactivity. They are among the greatest threats volcanoes pose to people and property. Lahars can occur with little to no warning, and may travel great distances at high speeds, destroying or burying everything in their paths.Lahars form in many ways. They commonly occur when eruptions melt snow and ice on snow-clad volcanoes; when rains fall on steep slopes covered with fresh volcanic ash; when crater lakes, volcano glaciers or lakes dammed by volcanic debris suddenly release water; and when volcanic landslides evolve into flowing debris. Lahars are especially likely to occur at erupting or recently active volcanoes.Because lahars are so hazardous, U.S. Geological Survey scientists pay them close attention. They study lahar deposits and limits of inundation, model flow behavior, develop lahar-hazard maps, and work with community leaders and governmental authorities to help them understand and minimize the risks of devastating lahars.

  4. Eruptive history of the Elysium volcanic province of Mars

    International Nuclear Information System (INIS)

    Tanaka, K.L.; Scott, D.H.

    1987-01-01

    New geologic mapping of the Elysium volcanic province at 1:2,000,000 scale and crater counts provide a basis for describing its overall eruptive history. Four stages are listed and described in order of their relative age. They are also distinguished by eruption style and location. Stage 1: Central volcanism at Hecates and Albor Tholi. Stage 2: Shield and complex volcanism at Elysium Mons and Elysium Fossae. Stage 3: Rille volcanism at Elysium Fossae and Utopia Planitia. Stage 4: Flood lava and pyroclastic eruptions at Hecates Tholus and Elysium Mons. Tectonic and channeling activity in the Elysium region is intimately associated with volcanism. Recent work indicates that isostatic uplift of Tharsis, loading by Elysium Mons, and flexural uplift of the Elysium rise produced the stresses responsible for the fracturing and wrinkle-ridge formation in the region. Coeval faulting and channel formation almost certainly occurred in the pertinent areas in Stages 2 to 4. Older faults east of the lava flows and channels on Hecates Tholus may be coeval with Stage 1

  5. Treatment of low-level radioactive waste using Volcanic ash

    International Nuclear Information System (INIS)

    Valdezco, E.M.; Marcelo, E.A.; Junio, J.B.; Caseria, E.S.; Salom, D.S.; Alamares, A.L.

    1997-01-01

    The effective application of volcanic ash, an indigenous adsorptive material abundant in the Mt. Pinatubo area, in the removal of radioiodine from radioactive waste streams was demonstrated. Factors such as availability, low cost and comparative retention capacity with respect to activated charcoal make volcanic ash an attractive alternative in the conditioning of radioactive waste containing radioiodine. Chemical precipitation was employed in the treatment of low level aqueous waste containing 137 Cs. It was shown that there exists an optimum concentration of ferric ion that promotes maximum precipitation of caesium. It was further demonstrated that complete removal of caesium can be achieved with the addition of nickel hexacyanoferrate. (author). 5 refs, 3 figs

  6. Treatment of low-level radioactive waste using Volcanic ash

    Energy Technology Data Exchange (ETDEWEB)

    Valdezco, E M; Marcelo, E A; Junio, J B; Caseria, E S; Salom, D S; Alamares, A L [Philippine Nuclear Research Inst., Manila (Philippines). Radiation Protection Services

    1997-02-01

    The effective application of volcanic ash, an indigenous adsorptive material abundant in the Mt. Pinatubo area, in the removal of radioiodine from radioactive waste streams was demonstrated. Factors such as availability, low cost and comparative retention capacity with respect to activated charcoal make volcanic ash an attractive alternative in the conditioning of radioactive waste containing radioiodine. Chemical precipitation was employed in the treatment of low level aqueous waste containing {sup 137}Cs. It was shown that there exists an optimum concentration of ferric ion that promotes maximum precipitation of caesium. It was further demonstrated that complete removal of caesium can be achieved with the addition of nickel hexacyanoferrate. (author). 5 refs, 3 figs.

  7. Metallogenetic regularity exploration model and prospecting potential of the mesocenozoic volcanic type uranium deposit in the east of south China

    International Nuclear Information System (INIS)

    Wang Yusheng; Li Wenjun

    1995-01-01

    During the Meso-Cenozoic era, the crust in the east of South China experienced an evolutional process of compression-relaxed extension-local disintegration, correspondingly, three periods of volcanic activity were developed, forming initial volcanic cycle, principal volcanic cycle and caldera volcanic cycle. The caldera volcanic cycle was expressed as a 'bimodal type' rock suite, indicating the entering of the region into an evolutional stage of new embryonic refitting. The volcanic type uranium deposit is characterized by ore-formation during caldera volcanic cycle, ore control by the mobile belt of caldera volcanic cycle and double superposition and concentration, and it can be summarized as a new unconformity-related type uranium deposit of caldera volcanic series, which is divided into three morphological types: body type, layer type and vein type and relevant exploration models are proposed. The new unconformity-related type uranium deposits of the caldera volcanic series in the east of South China have a great prospecting potential. The tectonomagmatic complex area of the caldera volcanic cycle developed on the granite basement is the favourable target area in searching for large uranium deposits from now on

  8. Volcanic Infrasound - A technical topic communicated in an entertaining way

    Science.gov (United States)

    Kerlow, Isaac

    2017-04-01

    Volcanic Infrasound is a 9-minute film about using infrasound waves to detect and measure volcanic eruptions as they unfold. The film was made by an interdisciplinary team of filmmakers and scientists for a general audience. The movie explains the basic facts of using infrasound to detect volcanic activity, and it also shows volcano researchers as they install infrasound sensors in a natural reserve in the middle of the city. This is the first in a series of films that seek to address natural hazards of relevance to Singapore, a country shielded from violent hazards. This presentation reviews the science communication techniques and assumptions used to develop and produce this entertaining scientific documentary short. Trailer: https://vimeo.com/192206460

  9. Global volcanic earthquake swarm database and preliminary analysis of volcanic earthquake swarm duration

    Directory of Open Access Journals (Sweden)

    S. R. McNutt

    1996-06-01

    Full Text Available Global data from 1979 to 1989 pertaining to volcanic earthquake swarms have been compiled into a custom-designed relational database. The database is composed of three sections: 1 a section containing general information on volcanoes, 2 a section containing earthquake swarm data (such as dates of swarm occurrence and durations, and 3 a section containing eruption information. The most abundant and reliable parameter, duration of volcanic earthquake swarms, was chosen for preliminary analysis. The distribution of all swarm durations was found to have a geometric mean of 5.5 days. Precursory swarms were then separated from those not associated with eruptions. The geometric mean precursory swarm duration was 8 days whereas the geometric mean duration of swarms not associated with eruptive activity was 3.5 days. Two groups of precursory swarms are apparent when duration is compared with the eruption repose time. Swarms with durations shorter than 4 months showed no clear relationship with the eruption repose time. However, the second group, lasting longer than 4 months, showed a significant positive correlation with the log10 of the eruption repose period. The two groups suggest that different suites of physical processes are involved in the generation of volcanic earthquake swarms.

  10. Initial discussion on ore-forming conditions and prospecting direction of volcanic type uranium deposits in the gangdise tectonic belt

    International Nuclear Information System (INIS)

    Zhao Baoguang; Wang Sili; Wang Qin; Sun Yue; Du Xiaolin; Chen Yuliang

    2010-01-01

    The most active volcanic activity in the Gangdise tectonic belt happened in early Cretaceous, Paleocene and Eocene, and Eocene is the most active period. The distribution of volcanic rock is controlled by latitudinal deep fault and deuteric longitudinal fault. Paleo-volcano was located at these structural compounds frequently. The volcanics which appeared near the merdional large scale pull-apart construction in Neogene is considered as land facies medium-acidic volcanics which brought by various kinds of volcanic basin. A large stream sediment anomaly (>6.8 x 10 -6 ) has been found at Cenozoic volcanics in south of CuoQin basin, and its areas amount to hundreds square kilometers. The uranium content of volcanics in Wuyu basin amounts to 20.0 x 10 -6 at most. It has favorable Ore-forming conditions for forming volcanic type uranium deposit due to the volcanic geologic environment, accompanying mineral, region feature of geochemistry and geophysical, volcanic-tectonic depression and so on. The major prospecting targets are the south of CuoQin basin and the Nanmulin district. (authors)

  11. Relative impact of on-road vehicular and point-source industrial emissions of air pollutants in a medium-sized Andean city

    Science.gov (United States)

    González, C. M.; Gómez, C. D.; Rojas, N. Y.; Acevedo, H.; Aristizábal, B. H.

    2017-03-01

    Cities in emerging countries are facing a fast growth and urbanization; however, the study of air pollutant emissions and its dynamics is scarce, making their populations vulnerable to potential effects of air pollution. This situation is critical in medium-sized urban areas built along the tropical Andean mountains. This work assesses the contribution of on-road vehicular and point-source industrial activities in the medium-sized Andean city of Manizales, Colombia. Annual fluxes of criteria pollutants, NMVOC, and greenhouse gases were estimated. Emissions were dominated by vehicular activity, with more than 90% of total estimated releases for the majority of air pollutants. On-road vehicular emissions for CO (43.4 Gg/yr) and NMVOC (9.6 Gg/yr) were mainly associated with the use of motorcycles (50% and 81% of total CO and NMVOC emissions respectively). Public transit buses were the main source of PM10 (47%) and NOx (48%). The per-capita emission index was significantly higher in Manizales than in other medium-sized cities, especially for NMVOC, CO, NOx and CO2. The unique mountainous terrain of Andean cities suggest that a methodology based on VSP model could give more realistic emission estimates, with additional model components that include slope and acceleration. Food and beverage facilities were the main contributors of point-source industrial emissions for PM10 (63%), SOx (55%) and NOx (45%), whereas scrap metal recycling had high emissions of CO (73%) and NMVOC (47%). Results provide the baseline for ongoing research in atmospheric modeling and urban air quality, in order to improve the understanding of air pollutant fluxes, transport and transformation in the atmosphere. In addition, this emission inventory could be used as a tool to identify areas of public health exposure and provide information for future decision makers.

  12. Using Digital Cameras to Detect Warning Signs of Volcanic Eruptions

    Science.gov (United States)

    Girona, T.; Huber, C.; Trinh, K. T.; Protti, M.; Pacheco, J. F.

    2017-12-01

    Monitoring volcanic outgassing is fundamental to improve the forecasting of volcanic eruptions. Recent efforts have led to the advent of new methods to measure the concentration and flux of volcanic gases with unprecedented temporal resolution, thus allowing us to obtain reliable high-frequency (up to 1 Hz) time series of outgassing activity. These high-frequency methods have shown that volcanic outgassing can be periodic sometimes (with periodicities ranging from 101 s to 103 s), although it remains unknown whether the spectral features of outgassing reflect the processes that ultimately trigger volcanic unrest and eruptions. In this study, we explore the evolution of the spectral content of the outgassing activity of Turrialba volcano (Costa Rica) using digital images (with digital brightness as a proxy for the emissions of water vapor [Girona et al., 2015]). Images were taken at 1 km distance with 1 Hz sampling rate, and the time period analyzed (from April 2016 to April 2017) is characterized by episodes of quiescent outgassing, ash explosions, and sporadic eruptions of ballistics. Our preliminary results show that: 1) quiescent states of Turrialba volcano are characterized by outgassing frequency spectra with fractal distribution; 2) superimposed onto the fractal frequency spectra, well-defined pulses with period around 100 s emerge hours to days before some of the eruptions of ballistics. An important conclusion of this study is that digital cameras can be potentially used in real-time volcano monitoring to detect warning signs of eruptions, as well as to better understand subsurface processes and track the changing conditions below volcanic craters. Our ongoing study also explores the correlation between the evolution of the spectral content of outgassing, infrasound data, and shallow seismicity. Girona, T., F. Costa, B. Taisne, B. Aggangan, and S. Ildefonso (2015), Fractal degassing from Erebus and Mayon volcanoes revealed by a new method to monitor H2O

  13. A bottom-up partnership of Andean institutions to improve hydrological interventions using a participatory network of research basins

    Science.gov (United States)

    Buytaert, W.; Ochoa-Tocachi, B. F.; De Bièvre, B.

    2017-12-01

    Many watershed interventions in remote data-scarce areas respond to information gaps by extrapolating conventional approaches based on very limited local evidence. However, most interventions, including conservation strategies and adaptation measures, have not been evaluated properly for their hydrological benefits. This is particularly the case for the Andean region, where the complex climatic and hydrological characteristics combined with a very dynamic anthropogenic disturbance, require better monitoring. Here, we present the experience of a partnership of academic and non-governmental institutions who pioneered participatory hydrological monitoring in the Andes. Established in 2009, the Regional Initiative for Hydrological Monitoring of Andean Ecosystems (iMHEA), is a bottom-up initiative that complements the national monitoring networks and more conventional scientific observatories. Using a design based on a trading-space-for-time approach, over 30 paired catchments with a variety of watershed interventions are currently being monitored by 18 local stakeholders in 15 sites in the tropical Andes. Pooling these data into a hydrological impact model allowed the consortium to make more robust predictions about the effectiveness of catchment interventions to improve water resources management and to reduce risks. The collaborative nature of iMHEA has several strengths. We identify as most important of those the ability to: (i) standardize monitoring practices; (ii) ensure quality and technical support; (iii) share responsibility of monitoring activities; (iv) obtain project co-funding and complementarity; and, (v) promote decision maker-scientist engagement. As a result, this network has started to deliver useful information to multi-scale and multi-stakeholder decision making arenas. For example, in the context of growing investment in hydrological ecosystem services in Peru, the sites provide a new generation of hydrological information that allows for evidence

  14. Improving the effectiveness of interventions and investment in Andean watersheds through a participatory network of research basins

    Science.gov (United States)

    Ochoa-Tocachi, B. F.; Buytaert, W.; De Bièvre, B.

    2016-12-01

    Many watershed interventions in remote data-scarce areas respond to information gaps by extrapolating conventional approaches based on very limited local evidence. However, most interventions, including conservation strategies and adaptation measures, have not been evaluated properly for their hydrological benefits. This is particularly the case for the Andean region, where the complex climatic and hydrological characteristics combined with a very dynamic anthropogenic disturbance, require better monitoring. Here, we