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Sample records for active central volcanoes

  1. July 1973 ground survey of active Central American volcanoes

    NASA Technical Reports Server (NTRS)

    Stoiber, R. E. (Principal Investigator); Rose, W. I., Jr.

    1973-01-01

    The author has identified the following significant results. Ground survey has shown that thermal anomalies of various sizes associated with volcanic activity at several Central American volcanoes should be detectable from Skylab. Anomalously hot areas of especially large size (greater than 500 m in diameter) are now found at Santiaguito and Pacaya volcanoes in Guatemala and San Cristobal in Nicaragua. Smaller anomalous areas are to be found at least seven other volcanoes. This report is completed after ground survey of eleven volcanoes and ground-based radiation thermometry mapping at these same points.

  2. Output rate of magma from active central volcanoes

    NASA Technical Reports Server (NTRS)

    Wadge, G.

    1980-01-01

    For part of their historic records, nine of the most active volcanoes on earth have each erupted magma at a nearly constant rate. These output rates are very similar and range from 0.69 to 0.26 cu m/s. The volcanoes discussed - Kilauea, Mauna Loa, Fuego, Santiaguito, Nyamuragira, Hekla, Piton de la Fournaise, Vesuvius and Etna - represent almost the whole spectrum of plate tectonic settings of volcanism. A common mechanism of buoyantly rising magma-filled cracks in the upper crust may contribute to the observed restricted range of the rates of output.

  3. Marapi an active West-Central Sumatra Volcano: a geological and petrological study

    NASA Astrophysics Data System (ADS)

    Del Marmol, M.; Budianto, A.; Fournelle, J.; Jacobs, P.; Elburg, M. A.

    2010-12-01

    Marapi volcano (West - Central Sumatra), Sumatra’s most active volcano (not to be confused with Merapi on Java), located in a densely populated area and where more than 50 explosive eruptions have been recorded in the last 200 years has been studied in detail in the field to gain fundamental understanding of the volcano's activity in terms of its basic geology, petrology and geochemistry. Marapi is one of a few active volcanoes among many dormant volcanoes of this island. Large deposits of the nearby Maninjau caldera, dated 50 ka (n=3), associated with very silica-rich volcanic products is another reason for concern, since caldera formation is linked with severe explosive activity. Those deposits are found at the base of the volcano and largely in the deeply incised valley which follows the Sumatra fault extending parallel to the Sumatra volcanic front. A possible landslide parallel to the Sumatra fault is recognized on the LANDSAT image. Landslides on the external old external side have allowed the collection of the oldest part of the volcano as most of it is covered with a thick primary forest. These landslides occurring on old volcanic terrain are a threat to the surrounding population living nearby the rivers especially during the heavy rainy seasons. A 20 m high stratigraphic column has been studied, with the volcano’s explosive nature seen in the collected samples (i.e. bombs and pumices). A new sketch map of the area of the craters (6 over 2km) replaces the one made in 1921 at the Dutch colonial time. A geological and hazard map have been created showing the extension of the various deposits.

  4. Volcanoes, Central Java, Indonesia

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The island of Java (8.0S, 112.0E), perhaps better than any other, illustrates the volcanic origin of Pacific Island groups. Seen in this single view are at least a dozen once active volcano craters. Alignment of the craters even defines the linear fault line of Java as well as the other some 1500 islands of the Indonesian Archipelago. Deep blue water of the Indian Ocean to the south contrasts to the sediment laden waters of the Java Sea to the north.

  5. Volcanic activity and satellite-detected thermal anomalies at Central American volcanoes

    NASA Technical Reports Server (NTRS)

    Stoiber, R. E. (Principal Investigator); Rose, W. I., Jr.

    1973-01-01

    The author has identified the following significant results. A large nuee ardente eruption occurred at Santiaguito volcano, within the test area on 16 September 1973. Through a system of local observers, the eruption has been described, reported to the international scientific community, extent of affected area mapped, and the new ash sampled. A more extensive report on this event will be prepared. The eruption is an excellent example of the kind of volcanic situation in which satellite thermal imagery might be useful. The Santiaguito dome is a complex mass with a whole series of historically active vents. It's location makes access difficult, yet its activity is of great concern to large agricultural populations who live downslope. Santiaguito has produced a number of large eruptions with little apparent warning. In the earlier ground survey large thermal anomalies were identified at Santiaguito. There is no way of knowing whether satellite monitoring could have detected changes in thermal anomaly patterns related to this recent event, but the position of thermal anomalies on Santiaguito and any changes in their character would be relevant information.

  6. Dynamical parameter analysis of continuous seismic signals of Popocatépetl volcano (Central Mexico): A case of tectonic earthquakes influencing volcanic activity

    NASA Astrophysics Data System (ADS)

    Tárraga, Marta; Cruz-Reyna, Servando; Mendoza-Rosas, Ana; Carniel, Roberto; Martínez-Bringas, Alicia; García, Alicia; Ortiz, Ramon

    2012-06-01

    The continuous background seismic activity contains information on the internal state of a volcanic system. Here, we report the influence of major regional tectonic earthquakes (M > 5 in most cases) on such state, reflected as changes in the spectral and dynamical parameters of the volcano continuous seismic data. Although changes do not always occur, analysis of five cases of earthquake-induced variations in the signals recorded at Popocatépetl volcano in central México reveal significant fluctuations following the tectonic earthquakes. External visible volcanic activity, such as small to moderate explosions and ash emissions, were related to those fluctuations. We briefly discuss possible causes of the variations. We conclude that recognition of fluctuations in the dynamical parameters in volcano monitoring seismic signals after tectonic earthquakes, even those located in the far field, hundreds of kilometers away, may provide an additional criterion for eruption forecasting, and for decision making in the definition of volcanic alert levels.

  7. Thematic mapper studies of central Andean volcanoes

    NASA Technical Reports Server (NTRS)

    Francis, Peter W.

    1987-01-01

    A series of false color composite images covering the volcanic cordillera was written. Each image is 45 km (1536 x 1536 pixels) and was constructed using bands 7, 4, and 2 of the Thematic Mapper (TM) data. Approximately 100 images were prepared to date. A set of LANDSAT Multispectral Scanner (MSS) images was used in conjunction with the TM hardcopy to compile a computer data base of all volcanic structure in the Central Andean province. Over 500 individual structures were identified. About 75 major volcanoes were identified as active, or potentially active. A pilot study was begun combining Shuttle Imaging Radar (SIR) data with TM for a test area in north Chile and Bolivia.

  8. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, Robert I.

    1987-01-01

    One of the most spectacular, awesomely beautiful, and at times destructive displays of natural energy is an erupting volcano, belching fume and ash thousands of meters into the atmosphere and pouring out red-hot molten lava in fountains and streams. Countless eruptions in the geologic past have produced volcanic rocks that form much of the Earth's present surface. The gradual disintegration and weathering of these rocks have yielded some of the richest farmlands in the world, and these fertile soils play a significant role in sustaining our large and growing population. Were it not for volcanic activity, the Hawaiian Islands with their sugar cane and pineapple fields and magnificent landscapes and seascapes would not exist to support their residents and to charm their visitors. Yet, the actual eruptive processes are catastrophic and can claim life and property.

  9. Active submarine volcano sampled

    USGS Publications Warehouse

    Taylor, B.

    1983-01-01

    On June 4, 1982, two full dredge hauls of fresh lava were recovered from the upper flanks of Kavachi submarine volcano, Solomon Islands, in the western Pacific Ocean, from the water depths of 1,200 and 2,700 feet. the shallower dredge site was within 0.5 mile of the active submarine vent shown at the surface by an area of slick water, probably caused by gas emissions. Kavachi is a composite stratovolcano that has been observed to erupt every year or two for at least the last 30 years (see photographs). An island formed in 1952, 1961, 1965, and 1978; but, in each case, it rapidly eroded below sea level. The latest eruption was observed by Solair pilots during the several weeks up to and including May 18, 1982. 

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

    NASA Astrophysics Data System (ADS)

    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

  11. Mount Rainier active cascade volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  12. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, R.I.

    1980-01-01

    One of the most spectacular, awesomely beautiful, and at times, most destructive displays of natural energy is an erupting volcano, belching fume and ash thousands of feet into the atmoshpehere and pouring out red-hot molten lava in fountains and streams. 

  13. A transect of Tertiary central volcanoes across northwest Iceland

    NASA Astrophysics Data System (ADS)

    Jordan, B. T.; Duncan, R. A.; Carley, T. L.

    2013-12-01

    The Skagi-Snaefellsnes rift zone (SSRZ) was the focus of rifting in Iceland from ~15-7 Ma. We report on a transect of central volcanoes and isolated exposures of silicic rocks erupted from the SSRZ in northwest Iceland. The youngest system investigated is an epizonal intrusive series, gabbro to granite, at the northern end of Vididalsfjall, near the axis of the SSRZ. The granite yields an Ar/Ar plateau age of 7.03 × 0.07 Ma (all dates ×2σ), and SHRIMP 206Pb/238U zircon analysis gives an age of 6.79 × 0.35 Ma (n=15). This represents the final silicic activity in the northern SSRZ prior to abandonment at this latitude. Just east of the SSRZ is a central volcano exposed in Vatnsdalsfjall, Langadalsfjall, and Laxardalsfjoll, informally termed the southern Skagi central volcano. Ar/Ar ages for intermediate to silicic rocks in this system include a 7.62 × 0.32 Ma dacite, 7.80 × 0.07 Ma andesite, and a 7.82 × 0.04 Ma rhyolite. The rhyolite was also dated by SHRIMP zircon analysis yielding an age of 7.62 × 0.29 Ma (n=19). The Arnes central volcano is exposed on the northeastern tip of the West Fjords peninsula, east of the SSRZ. Based on correlation with nearby dated paleomagnetic surveys the age is ~12 Ma. The Hrafnfjordur central volcano further west in the West Fjords may be the oldest central volcano exposed on land in Iceland. A SHRIMP zircon age for the main dacite lava is 14.16 × 0.40 Ma (n=14). The three central volcanoes feature nearly continuous compositional spectra from basalt to a high-silica dacite or rhyolite. Extensive rhyolites occur in southern Skagi and Arnes, but with 2/3 of the system mapped, there are no true rhyolites at Hrafnfjordur; the most extensive silicic unit is a dacite lava (65-70 wt.% SiO2). Variation in Zr vs. SiO2 seems to implicate a cryptic high-silica low-Zr rhyolite magma as an end-member of mixing for some andesites at Hrafnfjordur, but Zr/Ti disproves this. The origin of most of the silicic magmas is likely by crustal

  14. Petrologic diversity of Hrafnfjordur central volcano, northwest Iceland: Iceland's oldest central volcano

    NASA Astrophysics Data System (ADS)

    Jordan, B. T.

    2012-12-01

    Hrafnfjordur central volcano in northwest Iceland is exposed along the southern and western fjords of the Jokulfirdir, encompassing an area of ~400 km2. Field studies in 2004 and 2011 under the auspices of the Keck Geology Consortium investigated the southern and western portions of the Hrafnfjordur central volcano, mapping and sampling approximately 75% of the system. Hrafnfjordur central volcano has not been dated, but a basalt underlying tuff correlated to central volcano deposits yielded a whole-rock Ar/Ar plateau age of 14.20 +/- 0.33 (2σ) Ma (Jordan & Duncan, unpub. data). The dated lava is ~550 m below the tuff, and applying an accumulation rate of 1,600 m/m.y. (Kristjansson & Jonsson, 2007) produces an estimated age of ~13.9 Ma. This would make Hrafnfjordur the oldest central volcano exposed in Iceland. Mapping and sampling to this point have documented abundant andesite and dacite lavas, and several sequences of basalts and basaltic andesites. A notable feature of Hrafnfjordur central volcano is the absence of true rhyolites in the area mapped so far. A suite of dacites exposed in the fjord Hrafnfjordur exhibits a tight linear trend of decreasing Zr (1010-460 ppm) with increasing SiO2 (65.3-69.9 wt.%), indicating progressive zircon-involved fractionation. Elevated Zr/Nb of the parental dacite, relative to local basalts, precludes an origin by fractional crystallization from a basaltic parent, and thus its origin is interpreted to be crustal melting. A dacite exposed at Leirufjordur falls on the same trend and may correlate with those at Hrafnfjordur. Another trend of dacites and andesites sampled in both fjords is characterized by low Zr (160-200 ppm). This trend could represent magma mixing between basalt and a hypothetical highly evolved low-Zr high-silica rhyolite that either is not exposed or was never erupted. Most of the andesites and basaltic andesites plot on inflected trends consistent with an origin primarily by fractional crystallization from a

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

    NASA Astrophysics Data System (ADS)

    Londono, John Makario

    2016-09-01

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

  16. The Ilugissoq graphite andesite volcano, Nuussuaq, central West Greenland

    NASA Astrophysics Data System (ADS)

    Pedersen, Asger Ken; Larsen, Lotte Melchior

    2006-11-01

    The Ilugissoq graphite andesite volcano on Nuussuaq belongs to the Asuk Member of the Paleocene Vaigat Formation. It is the largest eruption site within the Vaigat Formation and is recognized as the source of the majority of the graphite andesite tuffs found in marine sediments in central Nuussuaq. The volcano consists exclusively of pyroclastic rocks containing a diverse lithic assemblage including sediment xenoliths. The primary pyroclastic fragments consist of magnesian andesite with several weight percent of graphite, which formed when mafic magma established a shallow-level magma reservoir beneath the eruption site, and within older clastic sediments from the Nuussuaq Basin. Magma-modified mudstone is completely dominant in the xenolith assemblage and attests that the graphite andesite originated through prolonged high-temperature assimilation of mudstone. The eruptions took place on a marine shelf consisting of picritic hyaloclastites and subaqueous crater mounds. The volcano consists of four overlapping crater cones aligned along a more than 4 km long NNW-SSE oriented fissure system; two cones barely reached sea level whereas the other two reached up to 200 m above the sea. The morphology of the pyroclastic rocks demonstrates that the volcano evolved through phreatomagmatic activity, which diminished with time. The magma never degassed sufficiently to reach a subaerial lava stage. A moderate primary gas pressure well in excess of 100 bars in the graphite andesite magma facilitated the phreatomagmatic explosions, which created the Ilugissoq volcano. The rocks of the volcano are rich in graphite and contain little or no native iron. In comparison, the contemporaneous and chemically similar subaerial lavas and breccias from Disko and Nuussuaq contain less graphite and more iron. The differences are considered to be due to the extremely pressure-dependent redox-sensitivity of carbon-oxygen equilibria in the range 1 bar (the lavas) to 500 bars (the Ilugissoq

  17. Volcanoes.

    ERIC Educational Resources Information Center

    Tilling, Robert I.

    One of a series of general interest publications on science topics, this booklet provides a non-technical introduction to the subject of volcanoes. Separate sections examine the nature and workings of volcanoes, types of volcanoes, volcanic geological structures such as plugs and maars, types of eruptions, volcanic-related activity such as geysers…

  18. Evolution of Irruputuncu volcano, Central Andes, northern Chile

    NASA Astrophysics Data System (ADS)

    Rodríguez, I.; Roche, O.; Moune, S.; Aguilera, F.; Campos, E.; Pizarro, M.

    2015-11-01

    The Irruputuncu is an active volcano located in northern Chile within the Central Andean Volcanic Zone (CAVZ) and that has produced andesitic to trachy-andesitic magmas over the last ˜258 ± 49 ka. We report petrographical and geochemical data, new geochronological ages and for the first time a detailed geological map representing the eruptive products generated by the Irruputuncu volcano. The detailed study on the volcanic products allows us to establish a temporal evolution of the edifice. We propose that the Irruputuncu volcanic history can be divided in two stages, both dominated by effusive activity: Irruputuncu I and II. The oldest identified products that mark the beginning of Irruputuncu I are small-volume pyroclastic flow deposits generated during an explosive phase that may have been triggered by magma injection as suggested by mingling features in the clasts. This event was followed by generation of large lava flows and the edifice grew until destabilization of its SW flank through the generation of a debris avalanche, which ended Irruputuncu I. New effusive activity generated lavas flows to the NW at the beginning of Irruputuncu II. In the meantime, lava domes that grew in the summit were destabilized, as shown by two well-preserved block-and-ash flow deposits. The first phase of dome collapse, in particular, generated highly mobile pyroclastic flows that propagated up to ˜8 km from their source on gentle slopes as low as 11° in distal areas. The actual activity is characterized by deposition of sulfur and permanent gas emissions, producing a gas plume that reaches 200 m above the crater. The maximum volume of this volcanic system is of ˜4 km3, being one of the smallest active volcano of Central Andes.

  19. 2011 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Maharrey, J. Zebulon; Neal, Christina A.

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest at or near three separate volcanic centers in Alaska during 2011. The year was highlighted by the unrest and eruption of Cleveland Volcano in the central Aleutian Islands. AVO annual summaries no longer report on activity at Russian volcanoes.

  20. Eruptive activity of enigmatic medium-sized volcanoes in the Michoacán-Guanajuato Volcanic Field (MGVF), Central Mexico: The case of El Metate

    NASA Astrophysics Data System (ADS)

    Chevrel, M.; Siebe, C.; Guilbaud, M. N.

    2014-12-01

    The MGVF has a total area of ca. 40,000 km2 and is well known for being the host of the only two monogenetic volcanoes in Mexico that were born in historical times: Jorullo (1759-1774) and Paricutin (1943-1952). Another particularity of the MGVF is its high number of eruptive vents with over 1000 small monogenetic cones and associated lava flows (average vol. of 0.021 km3) and ca. 400 medium-sized volcanoes (average vol. from 0.5 to 50 km3). Most of these medium-sized volcanoes may be characterized as shields that were produced dominantly by effusive activity as opposed to the small cones formed also by explosive phases of activity. The products of the small cones range from olivine basalts to andesites whereas the medium-sized volcanoes are restricted to a smaller compositional range in the andesitic domain. Although the medium-sized volcanoes are more sparsely distributed in time and space and less abundant than the small cones, the risks associated with renewal of this type of activity should not be neglected. This study focuses on El Metate which is probably the youngest shield of the MGVF (< 3,700 y. BP). Unlike a typical shield volcano composed of a succession of thin fluid basaltic flows, El Metate consists of well-preserved >60 m thick andesite flows distributed radially around a summit dome. Detailed mapping and sampling allowed us to reconstruct its eruptive activity and the time sequence of lava flow emplacement. We have identified 13 individual lava flows with lengths ranging between 3 and 15 km covering 103 km2 and average thicknesses between 60 and 150 m. Individual volumes range between 0.5 and 3.5 km3 for a total of 11 to 15 km3. Estimates of flow emplacement parameters indicate maximum average effusion rates ranging between 15 and 100 m3.s-1 and a cumulative duration from 15 to 30 years. Such a short emplacement time is comparable to the historical monogenetic eruption of nearby Paricutin volcano (9 years) but the erupted volume of lava is

  1. Seismicity at Fuego, Pacaya, Izalco, and San Cristobal Volcanoes, Central America, 1973-1974

    USGS Publications Warehouse

    McNutt, S.R.; Harlow, D.H.

    1983-01-01

    Seismic data collected at four volcanoes in Central America during 1973 and 1974 indicate three sources of seismicity: regional earthquakes with hypocentral distances greater than 80 km, earthquakes within 40 km of each volcano, and seismic activity originating at the volcanoes due to eruptive processes. Regional earthquakes generated by the underthrusting and subduction of the Cocos Plate beneath the Caribbean Plate are the most prominent seismic feature in Central America. Earthquakes in the vicinity of the volcanoes occur on faults that appear to be related to volcano formation. Faulting near Fuego and Pacaya volcanoes in Guatemala is more complex due to motion on a major E-W striking transform plate boundary 40 km north of the volcanoes. Volcanic activity produces different kinds of seismic signatures. Shallow tectonic or A-type events originate on nearby faults and occur both singly and in swarms. There are typically from 0 to 6 A-type events per day with b value of about 1.3. At very shallow depths beneath Pacaya, Izalco, and San Cristobal large numbers of low-frequency or B-type events are recorded with predominant frequencies between 2.5 and 4.5 Hz and with b values of 1.7 to 2.9. The relative number of B-type events appears to be related to the eruptive states of the volcanoes; the more active volcanoes have higher levels of seismicity. At Fuego Volcano, however, low-frequency events have unusually long codas and appear to be similar to tremor. High-amplitude volcanic tremor is recorded at Fuego, Pacaya, and San Cristobal during eruptive periods. Large explosion earthquakes at Fuego are well recorded at five stations and yield information on near-surface seismic wave velocities (??=3.0??0.2 km/sec.). ?? 1983 Intern. Association of Volcanology and Chemistry of the Earth's Interior.

  2. Orographic Flow over an Active Volcano

    NASA Astrophysics Data System (ADS)

    Poulidis, Alexandros-Panagiotis; Renfrew, Ian; Matthews, Adrian

    2014-05-01

    Orographic flows over and around an isolated volcano are studied through a series of numerical model experiments. The volcano top has a heated surface, so can be thought of as "active" but not erupting. A series of simulations with different atmospheric conditions and using both idealised and realistic configurations of the Weather Research and Forecast (WRF) model have been carried out. The study is based on the Soufriere Hills volcano, located on the island of Montserrat in the Caribbean. This is a dome-building volcano, leading to a sharp increase in the surface skin temperature at the top of the volcano - up to tens of degrees higher than ambient values. The majority of the simulations use an idealised topography, in order for the results to have general applicability to similar-sized volcanoes located in the tropics. The model is initialised with idealised atmospheric soundings, representative of qualitatively different atmospheric conditions from the rainy season in the tropics. The simulations reveal significant changes to the orographic flow response, depending upon the size of the temperature anomaly and the atmospheric conditions. The flow regime and characteristic features such as gravity waves, orographic clouds and orographic rainfall patterns can all be qualitatively changed by the surface heating anomaly. Orographic rainfall over the volcano can be significantly enhanced with increased temperature anomaly. The implications for the eruptive behaviour of the volcano and resulting secondary volcanic hazards will also be discussed.

  3. Volcano-Hydrothermal Systems of the Central and Northern Kuril Island Arc - a Review

    NASA Astrophysics Data System (ADS)

    Kalacheva, E.; Taran, Y.; Voloshina, E.; Ptashinsky, L.

    2015-12-01

    More than 20 active volcanoes with historical eruptions are known on 17 islands composing the Central and Northern part of the Kurilian Arc. Six islands - Paramushir, Shiashkotan, Rasshua, Ushishir, Ketoy and Simushir - are characterized by hydrothermal activity, complementary to the fumarolic activity in their craters. There are several types of volcano-hydrothermal systems on the islands. At Paramushir, Shiashkotan and Ketoy the thermal manifestations are acidic to ultra-acidic water discharges associated with hydrothermal aquifers inside volcano edifices and formed as the result of the absorption of magmatic gases by ground waters. A closest known analogue of such activity is Satsuma-Iwojima volcano-island at the Ryukyu Arc. Another type of hydrothermal activity are wide spread coastal hot springs (Shiashkotan, Rasshua), situated as a rule within tide zones and formed by mixing of the heated seawater with cold groundwater or, in opposite, by mixing of the steam- or conductively heated groundwater with seawater. This type of thermal manifestation is similar to that reported for other volcanic islands of the world (Satsuma Iwojima, Monserrat, Ischia, Socorro). Ushishir volcano-hydrothermal system is formed by the absorption of magmatic gases by seawater. Only Ketoy Island hosts a permanent acidic crater lake. At Ebeko volcano (Paramushir) rapidly disappearing small acidic lakes (formed after phreatic eruptions) have been reported. The main hydrothermal manifestation of Simushir is the Zavaritsky caldera lake with numerous coastal thermal springs and weak steam vents. The last time measured temperatures of fumaroles at the islands are: >500ºC at Pallas Peak (Ketoy), 480ºC at Kuntamintar volcano (Shiashkotan), variable and fast changing temperatures from 120º C to 500ºC at Ebeko volcano (Paramushir), 150ºC in the Rasshua crater, and > 300ºC in the Chirpoy crater (Black Brothers islands). The magmatic and rock-forming solute output by the Kurilian volcano

  4. The geological evolution of Merapi volcano, Central Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Gertisser, Ralf; Charbonnier, Sylvain J.; Keller, Jörg; Quidelleur, Xavier

    2012-07-01

    Merapi is an almost persistently active basalt to basaltic andesite volcanic complex in Central Java (Indonesia) and often referred to as the type volcano for small-volume pyroclastic flows generated by gravitational lava dome failures (Merapi-type nuées ardentes). Stratigraphic field data, published and new radiocarbon ages in conjunction with a new set of 40K-40Ar and 40Ar-39Ar ages, and whole-rock geochemical data allow a reassessment of the geological and geochemical evolution of the volcanic complex. An adapted version of the published geological map of Merapi [(Wirakusumah et al. 1989), Peta Geologi Gunungapi Merapi, Jawa Tengah (Geologic map of Merapi volcano, Central Java), 1:50,000] is presented, in which eight main volcano stratigraphic units are distinguished, linked to three main evolutionary stages of the volcanic complex—Proto-Merapi, Old Merapi and New Merapi. Construction of the Merapi volcanic complex began after 170 ka. The two earliest (Proto-Merapi) volcanic edifices, Gunung Bibi (109 ± 60 ka), a small basaltic andesite volcanic structure on Merapi's north-east flank, and Gunung Turgo and Gunung Plawangan (138 ± 3 ka; 135 ± 3 ka), two basaltic hills in the southern sector of the volcano, predate the Merapi cone sensu stricto. Old Merapi started to grow at ~30 ka, building a stratovolcano of basaltic andesite lavas and intercalated pyroclastic rocks. This older Merapi edifice was destroyed by one or, possibly, several flank failures, the latest of which occurred after 4.8 ± 1.5 ka and marks the end of the Old Merapi stage. The construction of the recent Merapi cone (New Merapi) began afterwards. Mostly basaltic andesite pyroclastic and epiclastic deposits of both Old and New Merapi (<11,792 ± 90 14C years BP) cover the lower flanks of the edifice. A shift from medium-K to high-K character of the eruptive products occurred at ~1,900 14C years BP, with all younger products having high-K affinity. The radiocarbon record points towards an

  5. Volcano deformation in central Main Ethiopian Rift system (Aluto Volcano) inferred from continuous GPS and dynamic gravity observations

    NASA Astrophysics Data System (ADS)

    Birhanu, Yelebe; Biggs, Juliet; Gottsmann, Joachim; Lewi, Elias; Lloyd, Ryan; Bekele, Berhanu

    2016-04-01

    Silicic volcanic centres in the rift systems frequently experience unrest indicating long-term activity in the underlying magmatic system, but it is difficult to distinguish the contributions of hydrothermal fluids, magma or gasses. Aluto volcano which is located in the central MER system is situated between the Lakes Ziway and Langano in the north and south respectively. Continuous GPS installed from April 2013 to October 2015 shows subsidence initially, with the largest subsidence observed in the eastern part of the caldera (2 cm/yr). InSAR observations from TerraSAR-X show a radially-symmetric pattern of long-term subsidence. Dynamic gravity surveys carried out in October 2014 and 2015 showed that there is a net mass loss in the western and central part of the caldera and mass gain in the eastern and southern part of the caldera, with a sharp gradient between the two. This complex spatial pattern of gravity change is significantly different to the simple pattern of deformation indicating multiple sources of pressure and mass change exist within the caldera. We explain the ratio of gravity to height change (dg/dh) throughout the volcano by considering cooling and crystallisation of magma body, draining and precipitation of hydrothermal fluids and changes in the water table and lake levels. Keywords: volcano deformation, dynamic gravity, continental rift

  6. Volcanoes in the pre-Columbian life, legend, and archaeology of Costa Rica (Central America)

    NASA Astrophysics Data System (ADS)

    Alvarado, Guillermo E.; Soto, Gerardo J.

    2008-10-01

    Costa Rica is located geographically in the southern part of the Central American Volcanic Front, a zone where interaction between the Mesoamerican and South American cultures occurred in pre-Columbian times. Several volcanoes violently erupted during the Holocene, when the first nomadic human hunters and later settlers were present. Volcanic rocks were the most important geo-resource in making artifacts and as construction materials for pre-Columbian inhabitants. Some pottery products are believed to resemble smoking volcanoes, and the settlements around volcanoes would seem to indicate their influence on daily life. Undoubtedly, volcanic eruptions disrupted the life of early settlers, particularly in the vicinity of Arenal and Irazú volcanoes, where archaeological remains show transient effects and displacement caused by periodical eruptions, but later resilient occupations around the volcanoes. Most native languages are extinct, with the exception of those presently spoken in areas far away from active volcanoes, where no words are related to volcanic phenomena or structures. The preserved legends are ambiguous, suggesting that they were either produced during the early Spanish conquest or were altered following the pre-Columbian period.

  7. Interaction between central volcanoes and fissure swarms along divergent plate boundaries: an example from Askja Volcano, Northern Iceland.

    NASA Astrophysics Data System (ADS)

    Trippanera, Daniele; Ruch, Joel; Acocella, Valerio; Urbani, Stefano; Thordarson, Thor

    2016-04-01

    Central volcanoes located along divergent plate boundaries are typically part of a larger volcanic system that consists of a central edifice and a fissure swarm through which magma propagates and spreads plates apart. Regional normal faults and graben structures develop within the volcanic system, also dissecting portions of the central volcano with ring-faults faults and eruptive fissures related to the caldera structure. Both the fissure swarm and the caldera structure influence the pathway of the ascending magma, however, the influences of the structures on magma propagation and vice versa are not well defined and understood. Here we aim to understand the relationship between the activity of the central volcano structures (e.g. caldera ring faults, radial dykes and cone sheets) and those of the fissure swarm (e.g. regional normal faults, regional dikes). We focus on Askja volcano, located in the Northern Volcanic Zone of Iceland. It is comprised of three nested calderas, largely filled in with subaerial basaltic lava flows and surrounded by a massive hyaloclastite mountain on the Eastern side. Formation of the youngest, the Öskjuvatn caldera, was initiated during the 1874-1876 rifting episode on the Askja system. This major event was followed by several localized radial and circumferential magmatic intrusions taking place along the new-formed caldera ring fault, as well as intruding in the fissure swarm related to the regional tectonics. In order to characterize the influence of the caldera structure on the regional tectonics, we analysed the structural framework of the caldera and direct surroundings using remote sensing (optical imagery and high resolution DEM from TanDEM-X data). Then we made detailed field measurements (500 data) by analysing azimuth, dip, and opening of eruptive fissures, dikes, faults and extension fractures. Both remote sensing and field measurements have been then integrated producing a detailed structural map of Askja. Our results show

  8. Climbing in the high volcanoes of central Mexico

    USGS Publications Warehouse

    Secor, R. J.

    1984-01-01

    A chain of volcanoes extends across central Mexico along the 19th parallel, a line just south of Mexico City. The westernmost of these peaks is Nevado de Colima at 4,636 feet above sea level. A subsidiary summit of Nevado de Colima is Volcan de Colima, locally called Fuego (fire) it still emits sulphurous fumes and an occasional plume of smoke since its disastrous eruption in 1941. Parictuin, now dormant, was born in the fall of 1943 when a cornfield suddenly erupted. Within 18 months, the cone grew more than 1,700 feet. Nevado de Toluca is a 15,433-foot volcanic peak south of the city of Toluca. Just southeast of Mexico City are two high volcanoes that are permanently covered by snow: Iztaccihuatl (17,342 fet) and Popocatepetl (17,887 feet) Further east is the third highest mountain in North America: 18,700-foot Citlateptl, or El Pico de Orizaba. North of these high peaks are two volcanoes, 14, 436-foot La Malinche and Cofre de Perote at 14,048 feet. This range of mountains is known variously as the Cordillera de Anahuac, the Sierra Volcanica Transversal, or the Cordillera Neovolcanica. 

  9. Silicic Magma Genesis in Neogene Central Volcanoes in Northeast Iceland

    NASA Astrophysics Data System (ADS)

    Berg, S. E.; Troll, V. R.; Riishuus, M. S.; Burchardt, S.; Krumbholz, M.

    2012-04-01

    We report on a geological expedition to NE Iceland in August 2011. A comprehensive sample suite of intrusive and extrusive rocks, ranging from basaltic to silicic compositions, was collected from the Neogene silicic central volcanic complexes in the region between Borgarfjörður eystri and Loðmundarfjörður. The area contains the second-most voluminous occurrence of silicic rocks in Iceland, including caldera structures, inclined sheet swarms, extensive ignimbrite sheets, sub-volcanic rhyolites and silicic lava flows. Yet it is one of Iceland's geologically least known areas (c.f. Gústafsson, 1992; Martin & Sigmarsson, 2010; Burchardt et al., 2011). The voluminous occurrence of evolved rocks in Iceland (10-12 %) is very unusual for an ocean island or a mid-oceanic ridge, with a typical signal of magmatic bimodality, often called "Bunsen-Daly" compositional gap (e.g. Bunsen, 1851; Daly, 1925; Barth et al., 1939). The Bunsen-Daly Gap is a long-standing fundamental issue in petrology and difficult to reconcile with continuous fractional crystallization as a dominant process in magmatic differentiation (Bowen, 1928), implying that hydrothermal alteration and crustal melting may play a significant role. Our aim is to contribute to a solution of this issue by unravelling the occurrence of voluminous evolved rhyolites in NE Iceland. We will use a combined petrological, textural, experimental and in-situ isotope approach. We plan to perform major, trace element and Sr-Nd-Hf-Pb-He-O isotope geochemistry, as well as U/Pb and Ar/Ar geochronology on rocks and mineral separates. In addition, high pressure-temperature partial melting experiments aim to reproduce and further constrain natural processes. Using the combined data set we intend to produce a comprehensive and quantitative analysis of rhyolite petrogenesis, and of the temporal, structural and geochemical evolution of the silicic volcanism in NE Iceland. The chosen field area serves as a good analogue for active

  10. Volcanoes

    ERIC Educational Resources Information Center

    Kunar, L. N. S.

    1975-01-01

    Describes the forces responsible for the eruptions of volcanoes and gives the physical and chemical parameters governing the type of eruption. Explains the structure of the earth in relation to volcanoes and explains the location of volcanic regions. (GS)

  11. Volcanoes

    SciTech Connect

    Decker, R.W.; Decker, B.

    1989-01-01

    This book describes volcanoes although the authors say they are more to be experienced than described. This book poses more question than answers. The public has developed interest and awareness in volcanism since the first edition eight years ago, maybe because since the time 120 volcanoes have erupted. Of those, the more lethal eruptions were from volcanoes not included in the first edition's World's 101 Most Notorious Volcanoes.

  12. Some Recent USF Studies at Volcanoes in Central America

    NASA Astrophysics Data System (ADS)

    McNutt, S. R.

    2014-12-01

    Scientists at the University of South Florida (USF) have been working in Central America for several decades. Efforts have focused on Physical Volcanology in Nicaragua, GPS in Costa Rica, and assessment of Geothermal projects in El Salvador, amongst others. Two years ago a Seismology Lab was established at USF. Personnel now include three Professors, a Post-Doc, and 4 graduate students. Seismic and GPS networks were installed at Telica Volcano, Nicaragua, in 2010 by Roman, LaFemina and colleagues. Data are recorded on site and recovered several times per year at this persistently restless volcano, which has rates of 5 to 1400 low frequency seismic events per day (Rodgers et al., submitted). Proposals have been submitted to install instruments on other Nicaraguan volcanoes, including seismometers, GPS, infrasound, and lightning sensors. This suite of instruments has proven to be very effective to study a range of volcanic processes. The proposals have not been successful to date (some are pending), and alternative funding sources are being explored. One interesting scientific issue is the presence of strong seasonal effects, specifically a pronounced rainy season and dry season and possible interaction between shallow volcanic processes and surface waters. We are also pursuing a variety of studies that are complementary to the instrumental efforts. One such study is examining volcanic earthquake swarms, with the focus to date on identifying diagnostics. One clear pattern is that peak rates often occur early in swarms, whereas the largest M event occurs late. Additional evidence suggests that the seismic source size grows systematically, especially for events with similar waveforms (families). Recognition of such patterns, linked to processes, may help to improve monitoring and better take advantage of instrumental data to reduce vulnerability from eruptions.

  13. Degassing Processes at Persistently Active Explosive Volcanoes

    NASA Astrophysics Data System (ADS)

    Smekens, Jean-Francois

    Among volcanic gases, sulfur dioxide (SO2) is by far the most commonly measured. More than a monitoring proxy for volcanic degassing, SO 2 has the potential to alter climate patterns. Persistently active explosive volcanoes are characterized by short explosive bursts, which often occur at periodic intervals numerous times per day, spanning years to decades. SO 2 emissions at those volcanoes are poorly constrained, in large part because the current satellite monitoring techniques are unable to detect or quantify plumes of low concentration in the troposphere. Eruption plumes also often show high concentrations of ash and/or aerosols, which further inhibit the detection methods. In this work I focus on quantifying volcanic gas emissions at persistently active explosive volcanoes and their variations over short timescales (minutes to hours), in order to document their contribution to natural SO2 flux as well as investigate the physical processes that control their behavior. In order to make these measurements, I first develop and assemble a UV ground-based instrument, and validate it against an independently measured source of SO2 at a coal-burning power plant in Arizona. I establish a measurement protocol and demonstrate that the instrument measures SO 2 fluxes with < 20 % error. Using the same protocol, I establish a record of the degassing patterns at Semeru volcano (Indonesia), a volcano that has been producing cycles of repeated explosions with periods of minutes to hours for the past several decades. Semeru produces an average of 21-71 tons of SO2 per day, amounting to a yearly output of 8-26 Mt. Using the Semeru data, along with a 1-D transient numerical model of magma ascent, I test the validity of a model in which a viscous plug at the top of the conduit produces cycles of eruption and gas release. I find that it can be a valid hypothesis to explain the observed patterns of degassing at Semeru. Periodic behavior in such a system occurs for a very narrow range

  14. Using the Landsat Thematic Mapper to detect and monitor active volcanoes - An example from Lascar volcano, northern Chile

    NASA Astrophysics Data System (ADS)

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

    1987-07-01

    The Landsat Thematic Mapper (TM) offers a means of detecting and monitoring thermal features of active volcanoes. Using the TM, a prominent thermal anomaly has been discovered on Lascar volcano, northern Chile. Data from two short-wavelength infrared channels of the TM show that material within a 300-m-diameter pit crater was at a temperature of at least 380 C on two dates in 1985. The thermal anomaly closely resembles in size and radiant temperature the anomaly over the active lava lake at Erta'ale in Ethiopia. An eruption took place at Lascar on Sept. 16, 1986. TM data acquired on Oct. 27, 1986, revealed significant changes within the crater area. Lascar is in a much more active state than any other volcano in the central Andes, and for this reason it merits further careful monitoring. Studies show that the TM is capable of confidently identifying thermal anomalies less than 100 m in size, at temperatures of above 150 C, and thus it offers a valuable means of monitoring the conditions of active or potentially active volcanoes, particularly those in remote regions.

  15. Using the Landsat Thematic Mapper to detect and monitor active volcanoes - An example from Lascar volcano, northern Chile

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    The Landsat Thematic Mapper (TM) offers a means of detecting and monitoring thermal features of active volcanoes. Using the TM, a prominent thermal anomaly has been discovered on Lascar volcano, northern Chile. Data from two short-wavelength infrared channels of the TM show that material within a 300-m-diameter pit crater was at a temperature of at least 380 C on two dates in 1985. The thermal anomaly closely resembles in size and radiant temperature the anomaly over the active lava lake at Erta'ale in Ethiopia. An eruption took place at Lascar on Sept. 16, 1986. TM data acquired on Oct. 27, 1986, revealed significant changes within the crater area. Lascar is in a much more active state than any other volcano in the central Andes, and for this reason it merits further careful monitoring. Studies show that the TM is capable of confidently identifying thermal anomalies less than 100 m in size, at temperatures of above 150 C, and thus it offers a valuable means of monitoring the conditions of active or potentially active volcanoes, particularly those in remote regions.

  16. Size, distribution, and magma output rate for shield volcanoes of the Michoacán-Guanajuato volcanic field, Central Mexico

    NASA Astrophysics Data System (ADS)

    Hasenaka, T.

    1994-10-01

    The Michoacán-Guanajuato Volcanic Field (MGVF), in the west-central Mexican Volcanic Belt (MVB), contains nearly 400 medium-sized volcanoes in addition to 1000 small monogenetic cones. The area is distinct from other parts of the MVB, where large composite volcanoes predominate. Shield volcanoes are dominant among medium-sized volcanoes, which also include minor lava domes and composite volcanoes. The location, height, basal diameter, and crater diameter (when applicable) of 378 medium-sized volcanoes were catalogued, and the slope angles and volumes were calculated from these data. The median shield volcano has a height of 340 m, a basal diameter of 4100 m, an average slope angle of 9.4°, and a volume of 1.7 km 3. The shield volcanoes in the MGVF are similar in size to Icelandic-type shield volcanoes, but the former have much higher slope angles and smaller basal diameters than the latter. Within the MGVF, these medium-sized volcanoes are located between 190 km and 430 km from the Middle America Trench; the distribution area is similar to that of small cones, but clusters and alignments are not as obvious for the medium-sized cones. The shield density is highest between 270 and 280 km from the Middle America Trench, 20 km farther than the density maximum for small cones. Ten medium-sized volcanoes were considered younger than 40,000 yr B.P. from lava flow morphology. The slope angle and a ratio of height to basal diameter are not useful age indicators, because they seem to reflect difference in original shield shape. K-Ar ages of shield volcanoes reveal that the volcanoes located north of latitude 19°55'N were active between 1 Ma and 3 Ma, whereas those south of latitude 19°55'N were active since 1 Ma. The average volcanic output rate estimated for the last 1 Ma is 0.7 km 3/1000 yr., whereas that for the period of 1-3 Ma is 0.2 km 3/1000 yr. An increase in magma production occurred around 1 Ma in response to migration of volcanism and probably to a change in

  17. Living on Active Volcanoes - The Island of Hawai'i

    USGS Publications Warehouse

    Heliker, Christina; Stauffer, Peter H.; Hendley, James W., II

    1997-01-01

    People on the Island of Hawai'i face many hazards that come with living on or near active volcanoes. These include lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and tsunamis (giant seawaves). As the population of the island grows, the task of reducing the risk from volcano hazards becomes increasingly difficult. To help protect lives and property, U.S. Geological Survey (USGS) scientists at the Hawaiian Volcano Observatory closely monitor and study Hawai'i's volcanoes and issue timely warnings of hazardous activity.

  18. 2009 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2014-01-01

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

  19. Underground structure of terrestrial mud volcanoes and abnormal water pressure formation in Niigata, Central JAPAN

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Shinya, T.; Miyata, Y.; Tokuyasu, S.

    2005-12-01

    Activity of mud volcano is thought to be caused by an abnormal water pressure generated in deep underground and make a serious problem for underground constructions such as railway tunnel, underground facility for radwaste and so on. It is important to investigate the underground structure of a mud volcano and the mechanism of abnormal water formation for site selection and safety assessment of such facilities. Serious trouble such as tunnel wall collapse due to the rock swelling has happened 180m deep under mud volcanoes. It took more than 10 years to excavate the section of 150 m long. 4 terrestrial mud volcanoes were found in the Tertiary sedimentary basin in Niigata, central Japan All the mud volcanoes are distributed along the rim of the topographic basin that is located at the NE-SW trending crest of mountainous area and distributed along the wing of anticline. Geological structure inside basin is heavily disturbed. The extinct mud volcano is exposed in the side-slope of newly constructed road and the internal vent structure of mud volcano can be observed. The vent is 30 m in diameter and is consisted of mud breccia and scaly network clay that is thought to be generated by hydro-fracturing and the following water-rock interaction between mudstone and groundwater. Groundwater erupted from mud volcano is highly saline with electric conductivity of 15 mS/cm and high 18 O/16 O isotope ratio of 1.2 parmillage. Also, the vitrinite reflectance is 1.5 to 1.9 % that is not expected in the sedimentary rocks exposed near ground surface. As a result, it is assumed that these erupted materials were introduced from the deep underground about 4000 m deep. CSA-MT geophysical exploration was carried out to survey the underground structure and obtained the profile of electrical resistivity from the surface to 800 m in depth. It is found that the disk-shaped low resistivity zone less than 1 m due to the high salinity content is identified in underground 600 m deep, 200 m thick

  20. Digital data set of volcano hazards for active Cascade Volcanos, Washington

    USGS Publications Warehouse

    Schilling, Steve P.

    1996-01-01

    Scientists at the Cascade Volcano Observatory have completed hazard assessments for the five active volcanos in Washington. The five studies included Mount Adams (Scott and others, 1995), Mount Baker (Gardner and others, 1995), Glacier Peak (Waitt and others, 1995), Mount Rainier (Hoblitt and others, 1995) and Mount St. Helens (Wolfe and Pierson, 1995). Twenty Geographic Information System (GIS) data sets have been created that represent the hazard information from the assessments. The twenty data sets have individual Open File part numbers and titles

  1. Kizimen Volcano, Kamchatka, Russia: 2010-2012 Eruptive Activity

    NASA Astrophysics Data System (ADS)

    Gordeev, E.; Droznin, V.; Malik, N.; Muravyev, Y.

    2012-12-01

    New eruptive activity at Kizimen Volcano began in October 2010 after 1.5 years of seismic build up. Two vents located at the summit of the volcano had been producing occasional steam-and-gas emissions with traces of ash until early December. Kizimen is located at a junction between Shapensky graben in the Central Kamchatka Depression and a horst of Tumrok Ridge. Kizimen is a 2376 m a.s.l. complex stratovolcano. The only single eruption reported in historic time occurred from December 1928 to January 1929. Little is known about the volcano; explosive activity was preceded by strong local earthquakes, and ashfalls were reported in neighboring settlements. During the period between eruptions the volcano was producing constant fumarolic activity, reported since 1825. During the cause of the current (2010-2012) eruption, the volcano produced several eruptive phases: moderate explosive activity was observed from December 10, 2010 to late February 2011 (ashfalls and descend of pyroclastic flows resulted in a large lahar traveling along the valley of the Poperechny Creek on December 13, 2010); from late February to mid-December the volcano produced an explosive-effusive phase (the lava flow descended eastern flank, while explosive activity has decreased), which resulted in strong explosions on December 14, 2011 accompanied by scores of pyroclastic flows of various thickness to the NE foot on the volcano. Since then, a constant growth of the large lava flow has been accompanied by strong steam-and-gas emissions from the summit crater. The erupted materials are tephra and deposits of pyroclastic and lava flows consisted of high-aluminous andesites and dacites of potassium-sodium series: SiO2 content varied from 61% in December 2010 to 65-68% in January-February 2011, and up to 62% in December 2011. Ashfalls area exceeded 100 km2 (the weight of erupted tephra > 107 tons), while the total area of pyroclastic flows was estimated to be 15.5 km2 (V= 0.16 km3). Until late May 2012

  2. Fluoride in ash leachates: environmental implications at Popocatépetl volcano, central Mexico

    NASA Astrophysics Data System (ADS)

    Armienta, M. A.; de La Cruz-Reyna, S.; Cruz, O.; Ceniceros, N.; Aguayo, A.; Marin, M.

    2011-07-01

    Ash emitted by volcanic eruptions, even of moderate magnitude, may affect the environment and the health of humans and animals through different mechanisms at distances significantly larger than those indicated in the volcanic hazard maps. One such mechanism is the high capacity of ash to transport toxic volatiles like fluoride, as soluble condensates on the particles' surface. The mobilization and hazards related to volcanic fluoride are discussed based on the data obtained during the recent activity of Popocatépetl volcano in Central Mexico.

  3. Global data collection and the surveillance of active volcanoes

    USGS Publications Warehouse

    Ward, P.L.

    1990-01-01

    Data relay systems on existing earth-orbiting satellites provide an inexpensive way to collect environmental data from numerous remote sites around the world. This technology could be used effectively for fundamental monitoring of most of the world's active volcanoes. Such global monitoring would focus attention on the most dangerous volcanoes that are likely to significantly impact the geosphere and the biosphere. ?? 1990.

  4. Seismic activity of Erebus volcano, antarctica

    NASA Astrophysics Data System (ADS)

    Kaminuma, Katsutada

    1987-11-01

    Mount Erebus is presently the only Antarctic volcano with sustained eruptive activity in the past few years. It is located on Ross Island and a convecting anorthoclase phonolite lava lake has occupied the summit crater of Mount Erebus from January 1973 to September 1984. A program to monitor the seismic activity of Mount Erebus named IMESS was started in December 1980 as an international cooperative program among Japan, the United States and New Zealand. A new volcanic episode began on 13 September, 1984 and continued until December. Our main observations from the seismic activity from 1982 1985 are as follows: (1) The average numbers of earthquakes which occurred around Mount Erebus in 1982, 1983 and January August 1984 were 64, 134 and 146 events per day, respectively. Several earthquake swarms occurred each year. (2) The averag number of earthquakes in 1985 is 23 events per day, with only one earthquake swarm. (3) A remarkable decrease of the background seismicity is recognized before and after the September 1984 activity. (4) Only a few earthquakes were located in the area surrounding Erebus mountain after the September 1984 activity. A magma reservoir is estimated to be located in the southwest area beneath the Erebus summit, based on the hypocenter distributions of earthquakes.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Volcanotectonic evolution of central Jordan: Evidence from the Shihan Volcano

    NASA Astrophysics Data System (ADS)

    Ibrahim, Khalil M.; Moh'd, Basem K.; Masri, Ahmad I.; Al-Taj, Masdouq M.; Musleh, Salem M.; Alzughoul, Khitam A.

    2014-12-01

    The E-W Siwaqa transcurrent fault is the result of tectonic activity related to the opening of the Red Sea and sinistral movement along the Dead Sea Transform (DST). During the translation and anticlockwise rotation of the Arabian Plate, dextral motion occurred along the Siwaqa Fault that resulted in opening of the crust and allowed lava to erupt intermittently from the Shihan Volcano, producing the Shihan Basalt Group. The stress field that formed the Siwaqa Fault and its related volcanic group is characterized by N-S to NNW-SSE compression and E-W to ENE-WSW extension, which is compatible with that known in Middle Miocene - Recent and related to the DST tectonic activity. The temporal and spatial distribution of the different volcanic formations was possibly affected by stress fluctuations. The first volcanic stage occurred prior to the formation of Wadi Mujib during the Messinian age. The latest erupted during the middle Pleistocene after the formation of Wadi Mujib. The Shihan Basalt Group consists of alkali olivine basalt, basanite and hawaiite. The basalt is subdivided into a silica saturated unit and an undersaturated silica unit. Crustal contamination is evident; variations in the basalt composition are due to different degrees of partial melting and fractional crystallization.

  7. Seismic imaging of the shallow crust beneath the Krafla central volcano, NE Iceland

    NASA Astrophysics Data System (ADS)

    Schuler, Juerg; Greenfield, Tim; White, Robert S.; Roecker, Steven W.; Brandsdóttir, Bryndís.; Stock, Joann M.; Tarasewicz, Jon; Martens, Hilary R.; Pugh, David

    2015-10-01

    We studied the seismic velocity structure beneath the Krafla central volcano, NE Iceland, by performing 3-D tomographic inversions of 1453 earthquakes recorded by a temporary local seismic network between 2009 and 2012. The seismicity is concentrated primarily around the Leirhnjúkur geothermal field near the center of the Krafla caldera. To obtain robust velocity models, we incorporated active seismic data from previous surveys. The Krafla central volcano has a relatively complex velocity structure with higher P wave velocities (Vp) underneath regions of higher topographic relief and two distinct low-Vp anomalies beneath the Leirhnjúkur geothermal field. The latter match well with two attenuating bodies inferred from S wave shadows during the Krafla rifting episode of 1974-1985. Within the Leirhnjúkur geothermalreservoir, we resolved a shallow (-0.5 to 0.5 km below sea level; bsl) region with low-Vp/Vs values and a deeper (0.5-1.5 km bsl) high-Vp/Vs zone. We interpret the difference in the velocity ratios of the two zones to be caused by higher rock porosities and crack densities in the shallow region and lower porosities and crack densities in the deeper region. A strong low-Vp/Vs anomaly underlies these zones, where a superheated steam zone within felsic rock overlies rhyolitic melt.

  8. A magma-hydrothermal system beneath Hakone volcano, central Japan, revealed by highly resolved velocity structures

    NASA Astrophysics Data System (ADS)

    Yukutake, Yohei; Honda, Ryou; Harada, Masatake; Arai, Ryuta; Matsubara, Makoto

    2015-05-01

    High-resolution images of subsurface structures are necessary to understand the transport processes of crustal fluids from deep magma sources and their relationship to earthquake swarms in active volcanic regions. Based on a seismic tomography approach, we have developed a new model for the magma-hydrothermal system beneath Hakone volcano, central Japan, where shallow earthquake swarms and crustal deformation associated with inflation of an open-crack source are often observed. By applying travel-time data for local earthquakes to a tomographic inversion, we obtained highly resolved seismic velocity structures that show a region of low P-wave velocity (Vp), low S-wave velocity (Vs), and high Vp/Vs ratios at depths of 10-20 km beneath the volcano, corresponding to the location of the open-crack source. We suggest that the high Vp/Vs ratios represent a deep magma chamber with a high concentration of melt and/or fluids. Deep low-frequency earthquakes, located just beneath this high Vp/Vs zone, may indicate that magmatic fluids are supplied from below. Above the high Vp/Vs zone, a region of low Vp, low Vs, and low Vp/Vs ratios exists at depths of 3-10 km, suggesting the presence of crack-filled water or CO2 supplied from the inferred deep magma chamber. Many earthquake swarms occur in this low Vp/Vs zone, indicating that crustal fluids play an important role in generating the swarms. Similar relationships between magma reservoirs, overlying hydrothermal systems, and swarm activity have been reported from other volcanic areas and thus may be a ubiquitous feature beneath active volcanoes.

  9. Toward a revised hazard assessment at Merapi volcano, Central Java

    NASA Astrophysics Data System (ADS)

    Thouret, J.-C.; Lavigne, F.; Kelfoun, K.; Bronto, S.

    2000-07-01

    Of 1.1 million people living on the flanks of the active Merapi volcano, 440,000 are at relatively high risk in areas prone to pyroclastic flows, surges, and lahars. For the last two centuries, the activity of Merapi has alternated regularly between long periods of viscous lava dome extrusion, and brief explosive episodes at 8-15 year intervals, which generated dome-collapse pyroclastic flows and destroyed part of the pre-existing domes. Violent explosive episodes on an average recurrence of 26-54 years have generated pyroclastic flows, surges, tephra-falls, and subsequent lahars. The 61 reported eruptions since the mid-1500s killed about 7000 people. The current hazard-zone map of Merapi (Pardyanto et al., 1978) portrays three areas, termed 'forbidden zone', 'first danger zone' and 'second danger zone', based on successively declining hazards. Revision of the hazard map is desirable, because it lacks details necessary to outline hazard zones with accuracy, in particular the valleys likely to be swept by lahars, and excludes some areas likely to be devastated by pyroclastic gravity-currents such as the 22 November 1994 surge. In addition, risk maps should be developed to incorporate social, technical, and economic factors of vulnerability. Eruptive hazard assessment at Merapi is based on reconstructed eruptive history, on eruptive behavior and scenarios, and on existing models and preliminary numerical modeling. Firstly, the reconstructed eruptive activity, in particular for the past 7000 years and from historical accounts of eruptions, helps to define the extent and recurrence frequency of the most hazardous phenomena (Newhall et al., 2000; Camus et al., 2000). Pyroclastic flows traveled as far as 9-15 km from the source, pyroclastic surges swept the flanks as far as 9-20 km away from the vent, thick tephra fall buried temples in the vicinity of Yogyakarta 25 km to the south, and subsequent lahars spilled down the radial valleys as far as 30 km to the west and

  10. Imaging an Active Volcano Edifice at Tenerife Island, Spain

    NASA Astrophysics Data System (ADS)

    Ibáñez, Jesús M.; Rietbrock, Andreas; García-Yeguas, Araceli

    2008-08-01

    An active seismic experiment to study the internal structure of Teide volcano is being carried out on Tenerife, a volcanic island in Spain's Canary Islands archipelago. The main objective of the Tomography at Teide Volcano Spain (TOM-TEIDEVS) experiment, begun in January 2007, is to obtain a three-dimensional (3-D) structural image of Teide volcano using seismic tomography and seismic reflection/refraction imaging techniques. At present, knowledge of the deeper structure of Teide and Tenerife is very limited, with proposed structural models based mainly on sparse geophysical and geological data. The multinational experiment-involving institutes from Spain, the United Kingdom, Italy, Ireland, and Mexico-will generate a unique high-resolution structural image of the active volcano edifice and will further our understanding of volcanic processes.

  11. The 7-8 August 2008 eruption of Kasatochi Volcano, central Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Waythomas, Christopher F.; Scott, William E.; Prejean, Stephanie G.; Schneider, David J.; Izbekov, Pavel; Nye, Christopher J.

    2010-12-01

    Kasatochi volcano in the central Aleutian Islands erupted unexpectedly on 7-8 August 2008. Kasatochi has received little study by volcanologists and has had no confirmed historical eruptions. The island is an important nesting area for seabirds and a long-term biological study site of the U.S. Fish and Wildlife Service. After a notably energetic preeruptive earthquake swarm, the volcano erupted violently in a series of explosive events beginning in the early afternoon of 7 August. Each event produced ash-gas plumes that reached 14-18 km above sea level. The volcanic plume contained large amounts of SO2 and was tracked around the globe by satellite observations. The cumulative volcanic cloud interfered with air travel across the North Pacific, causing many flight cancelations that affected thousands of travelers. Visits to the volcano in 2008-2009 indicated that the eruption generated pyroclastic flows and surges that swept all flanks of the island, accumulated several tens of meters of pyroclastic debris, and increased the diameter of the island by about 800 m. Pyroclastic flow deposits contain abundant accidental lithic debris derived from the inner walls of the Kasatochi crater. Juvenile material is crystal-rich silicic andesite that ranges from slightly pumiceous to frothy pumice. Fine-grained pyroclastic surge and fall deposits with accretionary lapilli cover the lithic-rich pyroclastic flow deposits and mark a change in eruptive style from episodic explosive activity to more continuous ash emission with smaller intermittent explosions. Pyroclastic deposits completely cover the island, but wave erosion and gully development on the flanks have begun to modify the surface mantle of volcanic deposits.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  13. The preliminary results: Seismic ambient noise Rayleigh wave tomography around Merapi volcano, central Java, Indonesia

    SciTech Connect

    Trichandi, Rahmantara; Yudistira, Tedi; Nugraha, Andri Dian; Zulhan, Zulfakriza; Saygin, Erdinc

    2015-04-24

    Ambient noise tomography is relatively a new method for imaging the shallow structure of the Earth subsurface. We presents the application of this method to produce a Rayleigh wave group velocity maps around the Merapi Volcano, Central Java. Rayleigh waves group velocity maps were reconstructed from the cross-correlation of ambient noise recorded by the DOMERAPI array which consists 43 broadband seismometers. In the processing stage, we first filtered the observation data to separatethe noise from the signal that dominated by the strong volcanic activities. Next, we cross-correlate the filtered data and stack to obtain the Green’s function for all possible station pairs. Then we carefully picked the peak of each Green’s function to estimate the dispersion trend and appliedMultiple Filter Technique to obtain the dispersion curve. Inter-station group velocity curvesare inverted to produceRayleigh wave group velocity maps for periods 1 to 10 s. The resulted Rayleigh group velocity maps show the interesting features around the Merapi Volcano which generally agree with the previous studies. Merapi-Lawu Anomaly (MLA) is emerged as a relatively low anomaly in our group velocity maps.

  14. Temporary seismic networks on active volcanoes of Kamchatka (Russia)

    NASA Astrophysics Data System (ADS)

    Jakovlev, Andrey; Koulakov, Ivan; Abkadyrov, Ilyas; Shapiro, Nikolay; Kuznetsov, Pavel; Deev, Evgeny; Gordeev, Evgeny; Chebrov, Viktor

    2016-04-01

    We present details of four field campaigns carried out on different volcanoes of Kamchatka in 2012-2015. Each campaign was performed in three main steps: (i) installation of the temporary network of seismic stations; (ii) autonomous continuous registration of three component seismic signal; (III) taking off the network and downloading the registered data. During the first campaign started in September 2012, 11 temporary stations were installed over the Avacha group of volcanoes located 30 km north to Petropavlovsk-Kamchatsky in addition to the seven permanent stations operated by the Kamchatkan Branch of the Geophysical Survey (KBGS). Unfortunately, with this temporary network we faced with two obstacles. The first problem was the small amount of local earthquakes, which were detected during operation time. The second problem was an unexpected stop of several stations only 40 days after deployment. Nevertheless, after taking off the network in August 2013, the collected data appeared to be suitable for analysis using ambient noise. The second campaign was conducted in period from August 2013 to August 2014. In framework of the campaign, 21 temporary stations were installed over Gorely volcano, located 70 km south to Petropavlovsk-Kamchatsky. Just in time of the network deployment, Gorely Volcano became very seismically active - every day occurred more than 100 events. Therefore, we obtain very good dataset with information about thousands of local events, which could be used for any type of seismological analysis. The third campaign started in August 2014. Within this campaign, we have installed 19 temporary seismic stations over Tolbachik volcano, located on the south side of the Klyuchevskoy volcano group. In the same time on Tolbachik volcano were installed four temporary stations and several permanent stations operated by the KBGS. All stations were taking off in July 2015. As result, we have collected a large dataset, which is now under preliminary analysis

  15. GlobVolcano pre-operational services for global monitoring active volcanoes

    NASA Astrophysics Data System (ADS)

    Tampellini, Lucia; Ratti, Raffaella; Borgström, Sven; Seifert, Frank Martin; Peltier, Aline; Kaminski, Edouard; Bianchi, Marco; Branson, Wendy; Ferrucci, Fabrizio; Hirn, Barbara; van der Voet, Paul; van Geffen, J.

    2010-05-01

    The GlobVolcano project (2007-2010) is part of the Data User Element programme of the European Space Agency (ESA). The project aims at demonstrating Earth Observation (EO) based integrated services to support the Volcano Observatories and other mandate users (e.g. Civil Protection) in their monitoring activities. The information services are assessed in close cooperation with the user organizations for different types of volcano, from various geographical areas in various climatic zones. In a first phase, a complete information system has been designed, implemented and validated, involving a limited number of test areas and respective user organizations. In the currently on-going second phase, GlobVolcano is delivering pre-operational services over 15 volcanic sites located in three continents and as many user organizations are involved and cooperating with the project team. The set of GlobVolcano offered EO based information products is composed as follows: Deformation Mapping DInSAR (Differential Synthetic Aperture Radar Interferometry) has been used to study a wide range of surface displacements related to different phenomena (e.g. seismic faults, volcanoes, landslides) at a spatial resolution of less than 100 m and cm-level precision. Permanent Scatterers SAR Interferometry method (PSInSARTM) has been introduced by Politecnico of Milano as an advanced InSAR technique capable of measuring millimetre scale displacements of individual radar targets on the ground by using multi-temporal data-sets, estimating and removing the atmospheric components. Other techniques (e.g. CTM) have followed similar strategies and have shown promising results in different scenarios. Different processing approaches have been adopted, according to data availability, characteristic of the area and dynamic characteristics of the volcano. Conventional DInSAR: Colima (Mexico), Nyiragongo (Congo), Pico (Azores), Areanal (Costa Rica) PSInSARTM: Piton de la Fournaise (La Reunion Island

  16. Seismicity and stress in the vicinity of Mount Spurr volcano, south central Alaska

    NASA Astrophysics Data System (ADS)

    Jolly, Arthur D.; Page, Robert A.; Power, John A.

    1994-08-01

    Focal mechanism solutions and hypocenters for earthquakes near Mount Spurr volcano in south central Alaska reveal spatial perturbations in the regional stress field and in the maximum depth of seismicity. At the volcano, practically all the shocks during the dormant decade 1981-1991 have depths shallower than 5 km and are characterized by nearly pure normal slip. In contrast, earthquakes located outboard of the volcano concentrate in the depth range 3-18 km and exhibit predominantly strike slip, oblique reverse slip, or reverse slip. The regional stress field is characterized by subhorizontal maximum principal stress directed N 30 deg W, concordant with the direction of convergence between the North American and Pacific plates, whereas the maximum principal stress is probably more nearly vertical beneath the volcano. We suggest that the shoaling of seismicity beneath the volcano reflects localized elevation of the depth to the midcrustal transition from brittle failure to plastic flow. We attribute this localized elevation to relict magmatic heat associated with past volcanic eruptions. The available data are not sufficient to determine the cause of the suggested rotation of the maximum principal stress axis beneath the volcano; possible mechanisms include an increase in the vertical stress from the weight of the Mount Spurr massif and a decrease in the maximum horizontal stress associated with doming of the shallow crust from magmatic processes.

  17. Measuring thermal budgets of active volcanoes by satellite remote sensing

    NASA Technical Reports Server (NTRS)

    Glaze, L.; Francis, P. W.; Rothery, D. A.

    1989-01-01

    Thematic Mapper measurements of the total radiant energy flux Q at Lascar volcano in north Chile for December 1984 are reported. The results are consistent with the earlier suggestion that a lava lake is the source of a reported thermal budget anomaly, and with values for 1985-1986 that are much lower, suggesting that fumarolic activity was then a more likely heat source. The results show that satellite remote sensing may be used to monitor the activity of a volcano quantitatively, in a way not possible by conventional ground studies, and may provide a method for predicting eruptions.

  18. Estimated pressure source on Kozu Island volcano, South Central Japan, from GPS measurements (July 1996-August 1999)

    NASA Astrophysics Data System (ADS)

    Kimata, Fumiaki; Kariya, Shin-ichi; Fujita, Masayuki; Matsumoto, Kunio; Tabei, Takao; Segawa, Jiro; Yamada, Akiko

    2000-11-01

    Although the Kozu Island Volcano, one of the Izu Islands Volcanoes in the south part Central Japan, is an active volcano, there is no record of the eruption for about 1100 years since the last eruption in 833 A.D. Since 1988, frequent earthquake swarms are observed around the Kozu Island, and the uplift of 2-4 cm/yr is observed on the island by tidal observations. Station velocities detected by GPS measurements since 1989 show velocities that differ from the convergent velocity of the Philippine Sea plate calculated from plate motion models. A local GPS network with 12 stations is occupied around the volcano, and the GPS measurements are repeated every about six month since July 1996. Inflated deformation of 2-4 cm/yr are detected from the GPS measurements and the pressure source is estimated to be located in the northeastern part of the island at a depth of 2.1 km using Mogi solution. Negative gravity changes of more than 30 microgal are also measured above the pressure source in the period November 1998 to July 1999, consistent with uplift.

  19. Seismically Articulating Kilauea Volcano's Active Conduits, Rift Zones, and Faults through HVO's Second Fifty Years

    NASA Astrophysics Data System (ADS)

    Okubo, P.; Nakata, J.; Klein, F.; Koyanagi, R.; Thelen, W.

    2011-12-01

    While seismic monitoring of active Hawaiian volcanoes began 100 years ago, the build-up of the U. S. Geological Survey's (USGS) Hawaiian Volcano Observatory (HVO) seismographic network to its current configuration began in 1955, when Jerry Eaton established remote stations that telemetered data via landline to recorders at HVO. With network expansion through the 1960's, earthquake location and cataloging capabilities have evolved to afford a computer processed seismic catalog now spanning fifty years. Location accuracy and catalog completeness to smaller magnitudes have increased. Research and insights developed using HVO's seismic record have exploited the ability to seismically monitor volcanic activity at depth, to identify active regions within the volcanoes on the basis of computed hypocentral locations, to infer regions of magma storage by recognizing different families of volcanic earthquakes, and to forecast volcanic activity in both short and longer term from seismicity patterns. HVO's seismicity catalog was central to calculations of probabilistic seismic hazards. The ability to develop and implement additional analytical and interpretive capabilities has kept pace with improvements in both field and laboratory hardware and software. While the basic capabilities continue as part of HVO's core monitoring, additional interpretive capabilities now include adding details of volcanic and earthquake source regions, and viewing seismic data in juxtaposition with other observatory data streams. As HVO looks to its next century of volcano studies, research and development continue to shape the future. Broadband seismic recording at HVO has enabled extensive study by Chouet, Dawson, and co-workers of the relationship of very-long-period seismic sources beneath Kilauea's summit caldera to magma supply and transport. Recent upgrades have improved the ability to use these data in seismic cataloging and research. Data processing upgrades have bolstered the ability to

  20. Temporal Variations of Magnetic Field Associated with Seismic Activity at Cerro Machin Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Londono, J. M.; Serna, J. P.; Guzman, J.

    2011-12-01

    A study of magnetic variations was carried out at Cerro Machin Volcano, Colombia for the period 2009 -2010, with two permanent magnetometers located at South and North of the central dome, separated about 2.5 km each other. After corrections, we found that there is no clear correlation between volcanic seismicity and temporal changes of magnetic field for each magnetometer station, if they are analyzed individually. On the contrary, when we calculated the residual Magnetic field (RMF), for each magnetometer, and then we made the subtraction between them, and plot it vs time, we found a clear correlation of changes in local magnetic field with the occurrence of volcanic seismicity (ML >1.6). We found a change in the RMF between 1584 nT and 1608 nT, each time that a volcano-tectonic earthquake occurred. The máximum lapse time between the previous change in RMF and the further occurrence of the earthquake is 24 days, with an average of 11 days. This pattern occurred more than 9 times during the studied period. Based on the results, we believed that the simple methodology proposed here, is a good tool for monitoring changes in seismicity associated with activity at Cerro Machín volcano. We suggest that the temporal changes of RMF at Cerro Machín Volcano, are associated with piezo-magnetic effects, due to changes in strain-stress inside the volcano, produced by the interaction between local faulting and magma movement.

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

    NASA Astrophysics Data System (ADS)

    Yamamoto, M.; Miura, S.

    2014-12-01

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

  2. Rootless Cone? Pingo? or Mud Volcano? in Central Elysium Planitia, Mars

    NASA Astrophysics Data System (ADS)

    Noguchi, R.; Kurita, K.

    2011-03-01

    It is possible that Mars has experienced recent (~100 Ma) magmatism. In central Elysium Planitia, the identification of cone-like landforms are discussed: rootless cones, pingos, or mud volcanos. From their morphology, the landforms are thought to be rootless cones.

  3. Multiple Active Volcanoes in the Northeast Lau Basin

    NASA Astrophysics Data System (ADS)

    Baker, E. T.; Resing, J. A.; Lupton, J. E.; Walker, S. L.; Embley, R. W.; Rubin, K. H.; Buck, N.; de Ronde, C. E.; Arculus, R. J.

    2010-12-01

    The northeast Lau Basin occupies a complex geological area between the Tafua arc front, the E-W trending Tonga Trench, and the Northeast Lau Spreading Center. These boundaries create multiple zones of extension and thus provide abundant opportunities for magma to invade the crust. The 25-km-long chain of “Mata” volcanoes lies near the center of this area, separated from both the arc front and the spreading ridge. In 2008 we discovered hydrothermal venting on the largest and most southerly of these volcanoes, W and E Mata. In 2010 we visited the 7 smaller volcanoes that form a 15-km-long arcuate sweep to the north from W and E Mata (the “North Matas”). We also revisited W and E Mata. Over each volcano we conducted CTD tows to map plumes and collect water samples. Based on the CTD results, camera tows searched for seafloor sources on three volcanoes. The N Mata volcanoes, extending from Mata Taha (1) in the south to Mata Fitu (7) in the north, lie within a prominent gap in the shallow bathymetry along the southern border of the Tonga trench. Northward from E Mata the Mata volcanoes degrade from large symmetrical cones to smaller and blocky volcanic edifices. Summit depths range from 1165 m (W Mata) to 2670 m (Mata Nima (5)). The most active volcano in the chain is the erupting W Mata, with an intense plume that extended 250 m above the summit. Hydrothermal temperature anomalies (Δθ, corrected for hydrographic masking effects) reached ˜1.7°C, with light-scattering values as high as 2-5 ΔNTU. The 2010 surveys now show that 6 of the 7 N Mata volcanoes are also hydrothermally active. Along the N Matas, Δθ and ΔNTU signals ranged from robust to weak, but distinct oxidation-reduction potential (aka Eh) anomalies confirmed active venting in each case. The most concentrated plumes were found near Mata Ua (2) and Mata Fitu (7), with Δθ and ΔNTU maxima of 0.1-0.17°C and 0.3, respectively. Despite the variability in plume strength, however, ΔNTU/Δθ ratios

  4. Linking petrology and seismology at an active volcano.

    PubMed

    Saunders, Kate; Blundy, Jon; Dohmen, Ralf; Cashman, Kathy

    2012-05-25

    Many active volcanoes exhibit changes in seismicity, ground deformation, and gas emissions, which in some instances arise from magma movement in the crust before eruption. An enduring challenge in volcano monitoring is interpreting signs of unrest in terms of the causal subterranean magmatic processes. We examined over 300 zoned orthopyroxene crystals from the 1980-1986 eruption of Mount St. Helens that record pulsatory intrusions of new magma and volatiles into an existing larger reservoir before the eruption occurred. Diffusion chronometry applied to orthopyroxene crystal rims shows that episodes of magma intrusion correlate temporally with recorded seismicity, providing evidence that some seismic events are related to magma intrusion. These time scales are commensurate with monitoring signals at restless volcanoes, thus improving our ability to forecast volcanic eruptions by using petrology. PMID:22628652

  5. Geoelectrical structure of the central zone of Piton de la Fournaise volcano (Reunion)

    USGS Publications Warehouse

    Lenat, J.-F.; Fitterman, D.; Jackson, D.B.; Labazuy, P.

    2000-01-01

    A study of the geoelectrical structure of the central part of Piton de la Fournaise volcano (Reunion, Indian Ocean) was made using direct current electrical (DC) and transient electromagnetic soundings (TEM). Piton de la Fournaise is a highly active oceanic basaltic shield and has been active for more than half a million years. Joint interpretation of the DC and TEM data allows us to obtain reliable 1D models of the resistivity distribution. The depth of investigation is of the order of 1.5 km but varies with the resistivity pattern encountered at each sounding. Two-dimensional resistivity cross sections were constructed by interpolation between the soundings of the 1D interpreted models. Conductors with resistivities less than 100 ohm-m are present at depth beneath all of the soundings and are located high in the volcanic edifice at elevations between 2000 and 1200 m. The deepest conductor has a resistivity less than 20 ohm-m for soundings located inside the Enclos and less than 60-100 ohm-m for soundings outside the Enclos. From the resistivity distributions, two zones are distinguished: (a) the central zone of the Enclos; and (b) the outer zone beyond the Enclos. Beneath the highly active summit area, the conductor rises to within a few hundred meters of the surface. This bulge coincides with a 2000-mV self-potential anomaly. Low-resistivity zones are inferred to show the presence of a hydrothermal system where alteration by steam and hot water has lowered the resistivity of the rocks. Farther from the summit, but inside the Enclos the depth to the conductive layers increases to approximately 1 km and is inferred to be a deepening of the hydrothermally altered zone. Outside of the Enclos, the nature of the deep, conductive layers is not established. The observed resistivities suggest the presence of hydrated minerals, which could be found in landslide breccias, in hydrothermally altered zones, or in thick pyroclastic layers. Such formations often create perched

  6. Long-term eruptive activity at a submarine arc volcano

    USGS Publications Warehouse

    Embley, R.W.; Chadwick, W.W., Jr.; Baker, E.T.; Butterfield, D.A.; Resing, J.A.; De Ronde, C. E. J.; Tunnicliffe, V.; Lupton, J.E.; Juniper, S.K.; Rubin, K.H.; Stern, R.J.; Lebon, G.T.; Nakamura, K.-I.; Merle, S.G.; Hein, J.R.; Wiens, D.A.; Tamura, Y.

    2006-01-01

    Three-quarters of the Earth's volcanic activity is submarine, located mostly along the mid-ocean ridges, with the remainder along intraoceanic arcs and hotspots at depths varying from greater than 4,000 m to near the sea surface. Most observations and sampling of submarine eruptions have been indirect, made from surface vessels or made after the fact. We describe here direct observations and sampling of an eruption at a submarine arc volcano named NW Rota-1, located 60 km northwest of the island of Rota (Commonwealth of the Northern Mariana Islands). We observed a pulsating plume permeated with droplets of molten sulphur disgorging volcanic ash and lapilli from a 15-m diameter pit in March 2004 and again in October 2005 near the summit of the volcano at a water depth of 555 m (depth in 2004). A turbid layer found on the flanks of the volcano (in 2004) at depths from 700 m to more than 1,400 m was probably formed by mass-wasting events related to the eruption. Long-term eruptive activity has produced an unusual chemical environment and a very unstable benthic habitat exploited by only a few mobile decapod species. Such conditions are perhaps distinctive of active arc and hotspot volcanoes. ?? 2006 Nature Publishing Group.

  7. The 2008 Eruption of Kasatochi Volcano, Central Aleutian Islands, Alaska: Reconnaissance Observations and Preliminary Physical Volcanology

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Schneider, D. J.; Prejean, S. G.

    2008-12-01

    The August 7, 2008 eruption of Kasatochi volcano was the first documented historical eruption of this small (3 x 3 km) island volcano with a 1 km2 lake filled crater in the central Aleutian Islands of Alaska. Reports of previous Kasatochi eruptions are unconfirmed and lacking in detail and little is known about the eruptive history. Three explosively-generated ash plumes reaching altitudes of 15 to 20 km were observed in satellite data and were preceded by some of the most intense seismicity yet recorded by the Alaska Volcano Observatory (AVO) seismic network. Eruptive products on Kasatochi Island observed on August 22 and 23 consist of pumice-bearing, lithic-rich pyroclastic-flow deposits overlain by a 1-2 m thick sequence of fine- grained pyroclastic-surge, and -fall deposits all exposed at the coastline. These deposits completely blanket Kasatochi Island to a depth of many meters. Pyroclastic flows entered the sea and extended the coastline 300-400 m beyond prominent wave cut cliffs and sea stacks. Tide gauge data from Adak Island, 80 km to the west, indicate a small tsunami with maximum water amplitude of 20 cm, was initiated during the eruption. Kasatochi volcano lacks a real-time seismic monitoring network. Seismic activity was detected by AVO instruments on Great Sitkin Island 40 km to the west, and thus the timing of eruptive events is approximate. The eruption began explosively at 2201 UTC on August 7, and was followed by at least two additional strong eruptive bursts at 0150 UTC and 0435 UTC, August 8. Satellite data show a significant ash cloud associated with the 0435 UTC event followed by at least 14 hours of continuous ash emission. The lack of a strong ash signature in satellite data suggest that the first two plumes were ash poor. Satellite data also show a large emission of SO2 that entered the stratosphere. Correlation of eruptive periods with deposits on the island is not yet possible, but it appears that pyroclastic flows were emplaced during

  8. Seismic Activity at Vailulu'u, Samoa's Youngest Volcano

    NASA Astrophysics Data System (ADS)

    Konter, J.; Staudigel, H.; Hart, S.

    2002-12-01

    Submarine volcanic systems, as a product of the Earth's mantle, play an essential role in the Earth's heat budget and in the interaction between the solid Earth and the hydrosphere and biosphere. Their eruptive and intrusive activity exerts an important control on these hydrothermal systems. In March 2000, we deployed an array of five ocean bottom hydrophones (OBH) on the summit region (625-995 m water depth) of Vailulu'u Volcano (14°12.9'S;169°03.5'W); this volcano represents the active end of the Samoan hotspot chain and is one of only a few well-studied intra-plate submarine volcanoes. We monitored seismic activity for up to 12 months at low sample rate (25 Hz), and for shorter times at a higher sample rate (125 Hz). We have begun to catalogue and locate a variety of acoustic events from this network. Ambient ocean noise was filtered out by a 4th-order Butterworth bandpass filter (2.3 - 10 Hz). We distinguish small local earthquakes from teleseismic activity, mostly identified by T- (acoustic) waves, by comparison with a nearby GSN station (AFI). Most of the detected events are T-phases from teleseismic earthquakes, characterized by their emergent coda and high frequency content (up to 30 Hz); the latter distinguishes them from low frequency emergent signals associated with the volcano (e.g. tremor). A second type of event is characterized by impulsive arrivals, with coda lasting a few seconds. The differences in arrival times between stations on the volcano are too small for these events to be T-waves; they are very likely to be local events, since the GSN station in Western Samoa (AFI) shows no arrivals close in time to these events. Preliminary locations show that these small events occur approximately once per day and are located within the volcano (the 95% confidence ellipse is similar to the size of the volcano, due to the small size of the OBH network). Several events are located relatively close to each other (within a km radius) just NW of the crater.

  9. Seismicity characteristics of a potentially active Quaternary volcano: The Tatun Volcano Group, northern Taiwan

    NASA Astrophysics Data System (ADS)

    Konstantinou, Konstantinos I.; Lin, Cheng-Horng; Liang, Wen-Tzong

    2007-02-01

    The Tatun Volcano Group (TVG) is located at the northern tip of Taiwan, near the capital Taipei and close to two nuclear power plants. Because of lack of any activity in historical times it has been classified as an extinct volcano, even though more recent studies suggest that TVG might have been active during the last 20 ka. In May 2003 a seismic monitoring project at the TVG area was initiated by deploying eight three-component seismic stations some of them equipped with both short-period and broadband sensors. During the 18 months observation period local seismicity mainly consisted of high frequency earthquakes either occurring as isolated events, or as a continuous sequence in the form of spasmodic bursts. Mixed and low frequency events were also present during the same period, even though they occurred only rarely. Arrival times from events with clear P-/S-wave phases were inverted in order to obtain a minimum 1D velocity model with station corrections. Probabilistic nonlinear earthquake locations were calculated for all these events using the newly derived velocity model. Most high frequency seismicity appeared to be concentrated near the areas of hydrothermal activity, forming tight clusters at depths shallower than 4 km. Relative locations, calculated using the double-difference method and utilising catalogue and cross-correlation differential traveltimes, showed insignificant differences when compared to the nonlinear probabilistic locations. In general, seismicity in the TVG area seems to be primarily driven by circulation of hydrothermal fluids as indicated by the occurrence of spasmodic bursts, mixed/low frequency events and a b-value (1.17 ± 0.1) higher than in any other part of Taiwan. These observations, that are similar to those reported in other dormant Quaternary volcanoes, indicate that a magma chamber may still exist beneath TVG and that a future eruption or period of unrest should not be considered unlikely.

  10. Instrumental lahar monitoring at Merapi Volcano, Central Java, Indonesia

    USGS Publications Warehouse

    Lavigne, F.; Thouret, J.-C.; Voight, B.; Young, K.; LaHusen, R.; Marso, J.; Suwa, H.; Sumaryono, A.; Sayudi, D.S.; Dejean, M.

    2000-01-01

    More than 50 volcanic debris flows or lahars were generated around Mt Merapi during the first rainy season following the nuees ardentes of 22 November 1994. The rainfalls that triggered the lahars were analyzed, using such instruments as weather radar and telemetered rain gauges. Lahar dynamics were also monitored, using new non-contact detection instrumentation installed on the slopes of the volcano. These devices include real-time seismic amplitude measurement (RSAM), seismic spectral amplitude measurement (SSAM) and acoustic flow monitoring (AFM) systems. Calibration of the various systems was accomplished by field measurements of flow velocities and discharge, contemporaneously with instrumental monitoring. The 1994–1995 lahars were relatively short events, their duration in the Boyong river commonly ranging between 30 min and 1 h 30 min. The great majority (90%) of the lahars was recognized at Kaliurang village between 13:00 and 17:30 h, due to the predominance of afternoon rainfalls. The observed mean velocity of lahar fronts ranged between 1.1 and 3.4 m/s, whereas the peak velocity of the flows varied from 11 to 15 m/s, under the Gardu Pandang viewpoint location at Kaliurang, to 8–10 m/s at a section 500 m downstream from this site. River slopes vary from 28 to 22 m/km at the two sites. Peak discharges recorded in various events ranged from 33 to 360 m3/s, with the maximum value of peak discharge 360 m3/s, on 20 May 1995. To improve the lahar warning system along Boyong river, some instrumental thresholds were proposed: large and potentially hazardous lahars may be detected by RSAM units exceeding 400, SSAM units exceeding 80 on the highest frequency band, or AFM values greater than 1500 mV on the low-gain, broad-band setting.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. China's Changbaishan volcano showing signs of increased activity

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-10-01

    Roughly 1100 years ago, the Changbaishan volcano that lies along the border between northeastern China and North Korea erupted, sending pyroclastic flows dozens of kilometers and blasting a 5-kilometer-wide chunk off of the tip of the stratovolcano. The eruption, known as the Millennium eruption because of its proximity to the turn of the first millennium, was one of the largest volcanic events in the Common Era. In the subsequent period, there have been three smaller eruptions, the most recent of which took place in 1903. Starting in 1999, spurred by signs of resumed activity, scientists established the Changbaishan Volcano Observatory, a network to track changing gas compositions, seismic activity, and ground deformation. Reporting on the data collected over the past 12 years, Xu et al. found that these volcanic indices each leapt during a period of heightened activity from 2002 to 2006.

  13. Numerical model of heat conduction in active volcanoes induced by magmatic activity

    NASA Astrophysics Data System (ADS)

    Atmojo, Antono Arif; Rosandi, Yudi

    2015-09-01

    We study the heat transfer mechanism of active volcanoes using the numerical thermal conduction model. A 2D model of volcano with its conduit filled by magma is considered, and acts as a constant thermal source. The temperature of the magma activity diffuses through the rock layers of the mountain to the surface. The conduction equation is solved using finite-difference method, with some adaptations to allow temperature to flow through different materials. Our model allows to simulate volcanoes having dikes, branch-pipes, and sills by constructing the domain appropriately, as well as layers with different thermal properties. Our research will show the possibility to monitor magma activity underneath a volcano by probing its surface temperature. The result of our work will be very useful for further study of volcanoes, eruption prediction, and volcanic disaster mitigation.

  14. Active Volcanoes of the Kurile Islands: A Reference Guide for Aviation Users

    USGS Publications Warehouse

    Neal, Christina A.; Rybin, Alexander; Chibisova, Marina; Miller, Edward

    2008-01-01

    Introduction: The many volcanoes of the remote and mostly uninhabited Kurile Island arc (fig. 1; table 1) pose a serious hazard for air traffic in the North Pacific. Ash clouds from Kurile eruptions can impact some of the busiest air travel routes in the world and drift quickly into airspace managed by three countries: Russia, Japan, and the United States. Prevailing westerly winds throughout the region will most commonly send ash from any Kurile eruption directly across the parallel North Pacific airways between North America and Asia (Kristine A. Nelson, National Weather Service, oral commun., 2006; fig. 1). This report presents maps showing locations of the 36 most active Kurile volcanoes plotted on Operational Navigational Charts published by the Defense Mapping Agency (map sheets ONC F-10, F-11, and E-10; figs. 1, 2, 3, 4). These maps are intended to assist aviation and other users in the identification of restless Kurile volcanoes. A regional map is followed by three subsections of the Kurile volcanic arc (North, Central, South). Volcanoes and selected primary geographic features are labeled. All maps contain schematic versions of the principal air routes and selected air navigational fixes in this region.

  15. Continuous gravity observations at active volcanoes through superconducting gravimeters

    NASA Astrophysics Data System (ADS)

    Carbone, Daniele; Greco, Filippo

    2016-04-01

    Continuous gravity measurements at active volcanoes are usually taken through spring gravimeters that are easily portable and do not require much power to work. However, intrinsic limitations dictate that, when used in continuous, these instruments do not provide high-quality data over periods longer than some days. Superconducting gravimeters (SG), that feature a superconducting sphere in a magnetic field as the proof mass, provide better-quality data than spring gravimeters, but are bigger and need mains electricity to work, implying that they cannot be installed close to the active structures of high volcanoes. An iGrav SG was installed on Mt. Etna (Italy) in September 2014 and has worked almost continuously since then. It was installed about 6km from the active craters in the summit zone of the volcano. Such distance is normally too much to observe gravity changes due to relatively fast (minutes to days) volcanic processes. Indeed, mass redistributions in the shallowest part of the plumbing system induce short-wavelength gravity anomalies, centered below the summit craters. Nevertheless, thanks to the high precision and long-term stability of SGs, it was possible to observe low-amplitude changes over a wide range of timescales (minutes to months), likely driven by volcanic activity. Plans are in place for the implementation of a mini-array of SGs at Etna.

  16. Magnetic Excursion Recorded in Basalt at Newberry Volcano, Central Oregon

    NASA Astrophysics Data System (ADS)

    Champion, D. E.; Donnelly-Nolan, J. M.; Lanphere, M. A.; Ramsey, D. W.

    2004-12-01

    Paleomagnetic study of basalt flows on the north flank of Newberry Volcano has identified a major eruptive episode that occurred during a magnetic excursion. The measured direction of the basalt flows erupted during the excursion shallows from 81° to 76° inclination along a declination of ˜ 155° . The Virtual Geomagnetic Pole also shallows from 29° to 19° paleolatitude, along a paleolongitude of ˜ 250° , and is located off the west coast of Mexico. Geologic evidence combined with limited argon dating indicate that the basalt erupted from multiple sites about 80,000 years ago, probably during the time of anomalous magnetic directions recorded by ( ˜80 ka) ocean sediments in the Norwegian Sea and the North Atlantic. The westernmost flows erupted from spatter vents located a few km south of the city of Bend, and flowed north through lava tube(s) which form Stevens Cave, Horse Cave, and Redmond Cave among others. This western lobe flowed more than 50 km to the north, over NW-trending faults of the Tumalo Fault Zone that cut the adjacent and underlying basalt of Bend (40Ar/39Ar plateau age of 78±9 ka; isochron age of 77±19 ka); it is overlain by the basaltic andesite of Klawhop Butte (40Ar/39Ar plateau age of 39±6 ka). One sample of the transitional magnetic direction basalt has a K-Ar age of 77±40 ka; another sample has a 40Ar/39Ar plateau age of 92±25 ka and an isochron age of 73±24 ka. The eastern lobe erupted from vents at and near Lava Top Butte, located approximately 15 km SE of the western vents. These eastern lavas flowed through Arnold Cave and formed a broad ~10-12 km rootless shield known as the Badlands, the NE extent of which is about 30 km from Lava Top Butte. The west and east lobes each cover about 150 km2, and comprise an estimated volume of 3-5 km3. Newly acquired 10-meter DEM's and compilation of the mapping in ArcGIS will allow more precise calculation of the total area covered and the volume erupted. Chemical analyses of multiple

  17. Mud volcanoes in central Italy: Subsoil characterization through a multidisciplinary approach

    NASA Astrophysics Data System (ADS)

    Rainone, M. L.; Rusi, S.; Torrese, P.

    2015-04-01

    Mud volcanoes are common geological phenomenons observed worldwide as in Italy. They are well described in the scientific literature for their morphological, tectonic and hydrogeological features. They represent not only a relevant geological and geomorphological interest but also not negligible elements of hazard and risk associated with the presence of soft and pliable sediments and with the possible unexpected emission of gas and mud. Therefore, the understanding of their structure and hydrogeological circuits in the subsurface is an important key to define hazard and risk conditions in the adjacent areas. This paper deals with a multidisciplinary study including geophysical and hydrochemical surveys undertaken at the Pineto (central Italy) mud volcano site to achieve an interpretative conceptual model explaining the shallow upward migration of deep mud fluids. Shallow electrical and seismic imaging of the mud volcano was obtained using two dimensional and three dimensional (2D-3D) electrical resistivity tomography and 2D reflection seismic surveys. The hydrochemical properties of the rising fluids were assessed by means of seasonal measurements of the chemical-physical parameters, the concentrations of major ions, and some natural isotopes. This mud volcano or mud lump appears as a dome of about 15 × 10 m in size. The height of the crater is 2 m approximately, while the diameter of the crater is 2.5 m. Emission of fluids and solids (cold brine, mud, gas) occurs from this crater. Upper Pliocene-lower Pleistocene foredeep pelitic deposits (over-compacted clays with silty-sandy levels) overlain by clayey-silty deposits crop out in the area. The survey results seem to reveal that the uprising of deep fluids does not occur exactly below the mud volcano at present. Instead, a high conductivity body is present within a fractured zone in the pelitic deposits at 60 m approximately to the ENE. The probable occurrence of a high permeability layer approximately between 20

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

    USGS Publications Warehouse

    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.

  19. Deep structure and origin of active volcanoes in China

    NASA Astrophysics Data System (ADS)

    Zhao, D.

    2010-12-01

    Recent geophysical studies have provided important constraints on the deep structure and origin of the active intraplate volcanoes in Mainland China. Magmatism in the western Pacific arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab (e.g., Zhao et al., 2009a), while the intraplate magmatism in China has different origins. The active volcanoes in Northeast China (such as the Changbai and Wudalianchi) are caused by hot upwelling in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well (Zhao et al., 2009b). The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate (or Indian plate) (Lei et al., 2009a). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and Indian slab's deep subduction in the west down to the lower mantle (Lei et al., 2009b; Zhao, 2009). The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions (Zhao, 2009). References Lei, J., D. Zhao, Y. Su, 2009a. Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data. J. Geophys. Res. 114, B05302. Lei, J., D. Zhao, B. Steinberger et al., 2009b. New seismic constraints on the upper mantle structure of the Hainan plume. Phys. Earth Planet. Inter. 173, 33-50. Zhao, D., 2009. Multiscale seismic tomography and mantle dynamics. Gondwana Res. 15, 297-323. Zhao, D., Z. Wang, N. Umino, A. Hasegawa, 2009a. Mapping the mantle wedge and interplate thrust zone of the northeast Japan arc. Tectonophysics 467, 89-106. Zhao, D., Y. Tian, J. Lei, L. Liu, 2009b. Seismic

  20. Active Volcano Monitoring using a Space-based Hyperspectral Imager

    NASA Astrophysics Data System (ADS)

    Cipar, J. J.; Dunn, R.; Cooley, T.

    2010-12-01

    Active volcanoes occur on every continent, often in close proximity to heavily populated areas. While ground-based studies are essential for scientific research and disaster mitigation, remote sensing from space can provide rapid and continuous monitoring of active and potentially active volcanoes [Ramsey and Flynn, 2004]. In this paper, we report on hyperspectral measurements of Kilauea volcano, Hawaii. Hyperspectral images obtained by the US Air Force TacSat-3/ARTEMIS sensor [Lockwood et al, 2006] are used to obtain estimates of the surface temperatures for the volcano. ARTEMIS measures surface-reflected light in the visible, near-infrared, and short-wave infrared bands (VNIR-SWIR). The SWIR bands are known to be sensitive to thermal radiation [Green, 1996]. For example, images from the NASA Hyperion hyperspectral sensor have shown the extent of wildfires and active volcanoes [Young, 2009]. We employ the methodology described by Dennison et al, (2006) to obtain an estimate of the temperature of the active region of Kilauea. Both day and night-time images were used in the analysis. To improve the estimate, we aggregated neighboring pixels. The active rim of the lava lake is clearly discernable in the temperature image, with a measured temperature exceeding 1100o C. The temperature decreases markedly on the exterior of the summit crater. While a long-wave infrared (LWIR) sensor would be ideal for volcano monitoring, we have shown that the thermal state of an active volcano can be monitored using the SWIR channels of a reflective hyperspectral imager. References: Dennison, Philip E., Kraivut Charoensiri, Dar A. Roberts, Seth H. Peterson, and Robert O. Green (2006). Wildfire temperature and land cover modeling using hyperspectral data, Remote Sens. Environ., vol. 100, pp. 212-222. Green, R. O. (1996). Estimation of biomass fire temperature and areal extent from calibrated AVIRIS spectra, in Summaries of the 6th Annual JPL Airborne Earth Science Workshop, Pasadena, CA

  1. Crustal structure of east central Oregon: Relation between Newberry Volcano and regional crustal structure

    NASA Astrophysics Data System (ADS)

    Catchings, R. D.; Mooney, W. D.

    1988-09-01

    A 180-km-long seismic refraction transect from the eastern High Cascades, across Newberry Volcano, to the eastern High Lava Plains is used to investigate the subvolcanic crustal and upper mantle velocity structure there. Near-surface volcanic flows and sedimentary debris (1.6-4.7 km/s), ranging from 3 to 5 km in thickness, overlie subvolcanic Basin and Range structures. East and west of Newberry Volcano, the subvolcanic basement (5.6 km/s) has been downwarped, producing 5-km-deep basins. The midcrust (8- to 28-km depth) is characterized by velocities ranging from 6.1 to 6.5 km/s and varies laterally in thicknesses. The lower crust is characterized by art unusually high velocity (about 7.4 km/s), and its geometry mirrors the subvolcanic basement geometry. The Moho is located at a depth of 37 km and represents a transition to an upper mantle velocity of 8.1 km/s. The shallow subsurface (1.2 km) beneath Newberry Volcano is characterized by high-velocity (5.6 km/s, versus 4.1 km/s for the surrounding area) intrusions and appears to be located on a basement high. Beneath the seismic refraction array at Newberry Volcano, an absence of low-velocity anomalies suggests that large silicic magma chambers do not exist in the upper crust, but apparent high attenuation of the seismic wave field may be consistent with either partial melts in small volumes, elevated crustal temperatures, and/or poor geophonerecording site coupling. The east central Oregon velocity structure is nearly identical to that of the northwestern Nevada Basin and Range and the Modoc Plateau of northeastern California, and variations in the deep crustal structure about Newberry Volcano are consistent with tectonism involving crustal underplating, melting, and extension. If paleomagnetic estimates of extension in the east central Oregon area are correct, the North American continent experienced significant growth through extension, underplating, and volcanism in east central Oregon. Comparison of east

  2. Venus lives!. [evidence for active volcanoes

    NASA Technical Reports Server (NTRS)

    Wood, Charles A.; Francis, Peter W.

    1988-01-01

    Observational evidence which supports the contention that Venus is a volcanically and tectonically active planet is discussed. It is argued that, although there are no observations to date that would prove that Venus has been volcanically active during the last decade, planetological studies presented evidence for youthful volcanic mountains on Venus: the surface of the northern quarter of Venus is considered to be younger than 1 Gy, and some units are likely to be much younger. Because of the small sizes of likely volcanic manifestations and the long intervals expected between eruptions, it is unlikely that any direct evidence of eruptions will be detected with existing and planned spacecraft. It is suggested that future studies of the dynamics and the chemical mixing of the Venusian atmosphere might supply an unequivocal evidence for active volcanism on this planet.

  3. Dike propagation in active volcanoes: importance, evidence, models and perspectives

    NASA Astrophysics Data System (ADS)

    Acocella, V.

    2011-12-01

    Most eruptions are fed by dikes; therefore, better knowledge of dike propagation is crucial to improve our understanding of how magma is transferred and extruded at volcanoes. Dike pattern data from a few tens of active volcanic edifices show how dike propagation in a volcano is not a random process; rather, it depends from the following factors (listed in order of importance): the presence of relief, the shape of the edifice, the proximity to the surface, and regional tectonic control. Relief enhances the development of radial dikes, which may also cluster following volcano elongation or regional patterns. Dikes approaching the surface of volcanic edifices, regardless of their initial orientation, reorient to become radial (parallel to the maximum gravitational stress); in presence of scarps, dikes reorient subparallel to the scarp (perpendicular to the minimum gravitational stress). These relationships have been also observed or inferred during eruptions at Etna, Stromboli, Vesuvio (Italy), Erta Ale (Afar) and Faial (Azores). While numerical modelling of dike propagation remains challenging, analogue models of dike emplacement have been performed over a few decades, also supporting part of the above-described evidence. Analogue models have been mostly conducted injecting air or water within gelatine and, recently, injecting vegetable oil within sand. More sophisticated analogue modelling is foreseen for the future, using a more appropriate scaling, a larger sensitivity and providing a more quantitative approach in capturing relationships. More in general, future research on dikes should be devoted towards identifying dike propagation paths, dike arrest mechanisms, and likely locations of vent formation at specific volcanoes, to better aid hazards assessment.

  4. Underwater observations of active lava flows from Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Tribble, G.W.

    1991-01-01

    Underwater observation of active submarine lava flows from Kilauea volcano, Hawaii, in March-June 1989 revealed both pillow lava and highly channelized lava streams flowing down a steep and unconsolidated lava delta. The channelized streams were 0.7-1.5 m across and moved at rates of 1-3 m/s. The estimated flux of a stream was 0.7 m3/s. Jets of hydrothermal water and gas bubbles were associated with the volcanic activity. The rapidly moving channelized lava streams represent a previously undescribed aspect of submarine volcanism. -Author

  5. Study of Seismic Activity at Ceboruco Volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Nunez-Cornu, F. J.; Escudero, C. R.; Rodríguez Ayala, N. A.; Suarez-Plascencia, C.

    2013-12-01

    Many societies and their economies endure the disastrous consequences of destructive volcanic eruptions. The Ceboruco stratovolcano (2,280 m.a.s.l.) is located in Nayarit, Mexico, at the west of the Mexican volcanic belt and towards the Sierra de San Pedro southeast, which is a key communication point for coast of Jalisco and Nayarit and the northwest of Mexico. It last eruptive activity was in 1875, and during the following five years it presents superficial activity such as vapor emissions, ash falls and riodacitic composition lava flows along the southeast side. Although surface activity has been restricted to fumaroles near the summit, Ceboruco exhibits regular seismic unrest characterized by both low frequency seismic events and volcano-tectonic earthquakes. From March 2003 until July 2008 a three-component short-period seismograph Marslite station with a Lennartz 3D (1Hz) was deployed in the south flank (CEBN) and within 2 km from the summit to monitoring the seismic activity at the volcano. The LF seismicity recorded was classified using waveform characteristics and digital analysis. We obtained four groups: impulsive arrivals, extended coda, bobbin form, and wave package amplitude modulation earthquakes. The extended coda is the group with more earthquakes and present durations of 50 seconds. Using the moving particle technique, we read the P and S wave arrival times and estimate azimuth arrivals. A P-wave velocity of 3.0 km/s was used to locate the earthquakes, most of the hypocenters are below the volcanic edifice within a circular perimeter of 5 km of radius and its depths are calculated relative to the CEBN elevation as follows. The impulsive arrivals earthquakes present hypocenters between 0 and 1 km while the other groups between 0 and 4 km. Results suggest fluid activity inside the volcanic building that could be related to fumes on the volcano. We conclude that the Ceboruco volcano is active. Therefore, it should be continuously monitored due to the

  6. Open-Vent Degassing of CO2 from Typical Andesitic Volcanoes in the Central American Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Robidoux, P.; Aiuppa, A.; Rotolo, S.; Giudice, G.; Moretti, R.; Conde, V.; Galle, B.; Tamburello, G.

    2014-12-01

    The collection of H2O-CO2-SO2 volcanic gas datasets at open-vent basaltic volcanoes has increased since the introduction of electrochemical/NDIR (Multi-GAS) instruments in the field. An open problem remains to understand the degassing regime of volcanoes of intermediate compositions, which is complicated by wide range of eruption styles. We propose here to initiate the study of the degassing regime of Telica and San Cristobal (Nicaragua), two constantly monitored volcanoes in the Central American Volcanic Arc (CAVA). We calculated the CO2 flux sustained by summit plume degassing at Telica and San Cristobal as the product of the CO2/SO2 ratio of Multi-GAS technique with parallel SO2 flux measurements, made by using scanning UV-DOAS instruments in 2013. At Telica, the CO2 flux was evaluated at 166±76 t/d and at San Cristobal we measured 520±260 t/d. Degassing activity at Telica volcano consists in surface gas discharges dominated by H2O (70-98 mol%; mean of 92 mol%), and by CO2 (1-23 mol%; mean of 6 mol%) and SO2 (0.5-7.4 mol%; mean of 2.9 mol%). San Cristobal gas is dominated by H2O (85-97 mol%; mean of 92 mol%), and by CO2 (2-12 mol%; mean of 6 mol%) and SO2 (3-5 mol%; mean of 3.8 mol%). These values are typical of volcanic arc regions and the volcanoes were in a stage of quiescent degassing without excess of CO2 output relatively to the other major gases. By interpreting our recent gas measurements in tandem with preliminary melt inclusion records of pre-eruptive dissolved volatile abundances, we hope to build a conceptual degassing model taking into account the active degassing regimes during past volcanic eruptions. Finally, we hope to refine the CO2 budget estimates along the CAVA.

  7. Seismicity at Uturuncu Volcano, Bolivia: Volcano-Tectonic Earthquake Swarms Triggered by the 2010 Maule, Chile Earthquake and Non-Triggered Background Activity

    NASA Astrophysics Data System (ADS)

    Christensen, D. H.; Chartrand, Z. A.; Jay, J.; Pritchard, M. E.; West, M. E.; McNutt, S. R.

    2010-12-01

    We find that the 270 ky dormant Uturuncu Volcano in SW Bolivia exhibits relatively high rates of shallow, volcano-tectonic seismicity that is dominated by swarm-like activity. We also document that the 27 February 2010 Mw 8.8 Maule, Chile earthquake triggered an exceptionally high rate of seismicity in the seconds to days following the main event. Although dormant, Uturuncu is currently being studied due to its large-scale deformation rate of 1-2 cm/yr uplift as revealed by InSAR. As part of the NASA-funded Andivolc project to investigate seismicity of volcanoes in the central Andes, a seismic network of 15 stations (9 Mark Products L22 short period and 6 Guralp CMG40T intermediate period sensors) with an average spacing of about 10 km was installed at Uturuncu from April 2009 to April 2010. Volcano-tectonic earthquakes occur at an average rate of about 3-4 per day, and swarms of 5-60 events within a span of minutes to hours occur a few times per month. Most of these earthquakes are located close to the summit at depths near and above sea level. The largest swarm occurred on 28 September 2009 and consisted of 60 locatable events over a time span of 28 hours. The locations of volcano-tectonic earthquakes at Uturuncu are oriented in a NW-SE trend, which matches the dominant orientation of regional faults and suggests a relationship between the fault system at Uturuncu and the regional tectonics of the area; a NW-SE trending fault beneath Uturuncu may serve to localize stresses that are accumulating over the broad area of uplift. Based on automated locations, the maximum local magnitude of these events is approximately M = 4 and the average magnitude is approximately M = 2. An initial estimate of the b-value is about b = 1.2. The Mw 8.8 Maule earthquake on 27 February 2010 triggered hundreds of local volcano-tectonic events at Uturuncu. High-pass filtering of the long period surface waves reveals that the first triggered events occurred with the onset of the Rayleigh

  8. Interagency collaboration on an active volcano: a case study at Hawai‘i Volcanoes National Park

    USGS Publications Warehouse

    Kauahikaua, James P.; Orlando, Cindy

    2014-01-01

    Because Kilauea and Mauna Loa are included within the National Park, there is a natural intersection of missions for the National Park Service (NPS) and the U.S. Geological Survey (USGS). HAVO staff and the USGS Hawaiian Volcano Observatory scientists have worked closely together to monitor and forecast multiple eruptions from each of these volcanoes since HAVO’s founding in 1916.

  9. A Broadly-Based Training Program in Volcano Hazards Monitoring at the Center for the Study of Active Volcanoes

    NASA Astrophysics Data System (ADS)

    Thomas, D. M.; Bevens, D.

    2015-12-01

    The Center for the Study of Active Volcanoes, in cooperation with the USGS Volcano Hazards Program at HVO and CVO, offers a broadly based volcano hazards training program targeted toward scientists and technicians from developing nations. The program has been offered for 25 years and provides a hands-on introduction to a broad suite of volcano monitoring techniques, rather than detailed training with just one. The course content has evolved over the life of the program as the needs of the trainees have changed: initially emphasizing very basic monitoring techniques (e.g. precise leveling, interpretation of seismic drum records, etc.) but, as the level of sophistication of the trainees has increased, training in more advanced technologies has been added. Currently, topics of primary emphasis have included volcano seismology and seismic networks; acquisition and modeling of geodetic data; methods of analysis and monitoring of gas geochemistry; interpretation of volcanic deposits and landforms; training in LAHARZ, GIS mapping of lahar risks; and response to and management of volcanic crises. The course also provides training on public outreach, based on CSAV's Hawaii-specific hazards outreach programs, and volcano preparedness and interactions with the media during volcanic crises. It is an intensive eight week course with instruction and field activities underway 6 days per week; it is now offered in two locations, Hawaii Island, for six weeks, and the Cascades volcanoes of the Pacific Northwest, for two weeks, to enable trainees to experience field conditions in both basaltic and continental volcanic environments. The survival of the program for more than two decades demonstrates that a need for such training exists and there has been interaction and contribution to the program by the research community, however broader engagement with the latter continues to present challenges. Some of the reasons for this will be discussed.

  10. Review of eruptive activity at Tianchi volcano, Changbaishan, northeast China: implications for possible future eruptions

    NASA Astrophysics Data System (ADS)

    Wei, Haiquan; Liu, Guoming; Gill, James

    2013-04-01

    One of the largest explosive eruptions in the past several thousand years occurred at Tianchi volcano, also known as Changbaishan, on the China-North Korea border. This historically active polygenetic central volcano consists of three parts: a lower basaltic shield, an upper trachytic composite cone, and young comendite ash flows. The Millennium Eruption occurred between 938 and 946 ad, and was preceded by two smaller and chemically different rhyolitic pumice deposits. There has been at least one additional, small eruption in the last three centuries. From 2002 to 2005, seismicity, deformation, and the helium and hydrogen gas contents of spring waters all increased markedly, causing regional concern. We attribute this event to magma recharge or volatile exhalation or both at depth, followed by two episodes of addition of magmatic fluids into the overlying aquifer without a phreatic eruption. The estimated present magma accumulation rate is too low by itself to account for the 2002-2005 unrest. The most serious volcanic hazards are ash eruption and flows, and lahars. The available geological information and volcano monitoring data provide a baseline for comprehensive assessment of future episodes of unrest and possible eruptive activity.

  11. Scaling and Transition of the Explosive Activity at Stromboli Volcano

    NASA Astrophysics Data System (ADS)

    Ripepe, M.; Marchetti, E.; Genco, R.; Lacanna, G.; Delle Donne, D.; Valade, S.; Ulivieri, G.

    2014-12-01

    Explosive activity at Stromboli volcano covers a wide energetic and temporal spectrum, spanning from small puffing to violent paroxysms and with the corresponding mass discharge rate ranging 7 orders of magnitude. At the lowest end, puffing activity is characterized by discrete small pulses of gas and fragments with limited excess pressure, driving gas and ejecta at the rate of 1 kg/s few meters high above the vents and repeating almost persistently at the rate of ~ 1 event every 2 seconds. With increasing mass discharge rate ordinary explosive activity (103 kg/s) is repeating every ~ few minutes ejecting hot lava fragments at ~200 m height whereas larger (Mayor) explosions are occurring every year with a mass eruptive rate of 105 kg/s driving progressively higher eruptive clouds at ~500 m above the vent. At the other end of the activity, the paroxysms have a mass discharge rate of 107 kg/s, driving the eruptive column up to few km above the crater and repeating at a rate of one event every ~10 years. Clear limits among these different eruptive styles have not been defined and the dynamics driving this broad explosive spectrum is still debated. We show how seismic, ground tilt and infrasonic data collected at Stromboli since 2008 for a total of ~24000 events provide a geophysical-based classification of explosive activity at Stromboli volcano highlighting changes in eruptive dynamics.

  12. Application of scientific core drilling to geothermal exploration: Platanares, Honduras and Tecuamburro Volcano, Guatemala, Central America

    SciTech Connect

    Goff, S.J.; Goff, F.E.; Heiken, G.H.; Duffield, W.A.; Janik, C.J.

    1994-04-01

    Our efforts in Honduras and Guatemala were part of the Central America Energy Resource Project (CAERP) funded by the United States Agency for International Development (AID). Exploration core drilling operations at the Platanares, Honduras and Tecuamburro Volcano, Guatemala sites were part of a geothermal assessment for the national utility companies of these countries to locate and evaluate their geothermal resources for electrical power generation. In Honduras, country-wide assessment of all thermal areas determined that Platanares was the site with the greatest geothermal potential. In late 1986 to middle 1987, three slim core holes were drilled at Platanares to a maximum depth of 680 m and a maximum temperature of 165{degree}C. The objectives were to obtain information on the geothermal gradient, hydrothermal alterations, fracturing, and possible inflows of hydrothermal fluids. Two holes produced copious amounts of water under artesian conditions and a total of 8 MW(t) of energy. Geothermal investigations in Guatemala focused on the Tecuamburro Volcano geothermal site. The results of surface geological, volcanological, hydrogeochemical, and geophysical studies at Tecuamburro Volcano indicated a substantial shallow heat source. In early 1990 we drilled one core hole, TCB-1, to 808 m depth. The measured bottom hole temperature was 238{degree}C. Although the borehole did not flow, in-situ samples indicate the hole is completed in a vapor-zone above a probable 300{degree}C geothermal reservoir.

  13. The explosive activity of the Colima volcano in 2005

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nuñez-Cornu, F.; Diaz-Torres, J.

    2005-12-01

    The Colima volcano, Mexico, showed a new cycle of explosive activity beginning in March and April the 2005. This increased gradually and in May it appeared an explosive event which generated piroclastic flows on all flanks of the volcano. On May 23 a new dome was created, and it was observed from the Volcanological Observatory of the Nevado de Colima. Hours later its dome was destroyed by a strong explosion, which formed a column 3 km hight and piroclastic flows that reached a distance of 5 km on the ravines of the South sector. On May 30 the most intense explosion from 1999 occurred when the plume reached heights over 3.500 m above the crater, and piroclastic flows. In the month of June it generated four explosive events of characteristics similar to those of May. These constant explosions caused constant morphological changes on the top, being the most significant the collapse of the North and South walls of the crater in the first week of June, and the creation of a new crater in July. This activity was similar to the one shown in 1902-1903 and reported by Severo Diaz (1906), but without reaching the maximum levels of activity reported for 1903, where it had levels of three to five maximum explosive events per day. The explosions deposited great amount of nonconsolidated materials, like ash, lithics and rocks on the flanks of the volcano, which with the present rainy season have generated lahares, two in the month of June, ten in July and eight in August (RESCO reports). These have flowed in small flows on the ravines of La Lumbre, Montegrande, San Antonio and La Arena. None of them have caused damages until August, 2005.

  14. Seismic exploration of Fuji volcano with active sources in 2003

    NASA Astrophysics Data System (ADS)

    Oikawa, J.; Kagiyama, T.; Tanaka, S.; Miyamachi, H.; Tsutsui, T.; Ikeda, Y.; Katayama, H.; Matsuo, N.; Oshima, H.; Nishimura, Y.; Yamamoto, K.; Watanabe, T.; Yamazaki, F.

    2004-12-01

    the Tanzawa Range to the east. This uplifted body is formed by plate subduction and collision with the Izu Peninsula, and is believed to have influence at significant depth. This is considered to be the reason for the change in the geologic structure beneath Fuji volcano from west to east. The dome structure of the bedrock layer (second layer) directly beneath the summit is considered to have formed in the initial period of volcanic activity that formed Mt. Fuji, leading to the subsequent formation of Komitake volcano, Ko-Fuji volcano and the present day Fuji volcano.

  15. Explosion energy of the 2004 eruption of the Asama Volcano, central Japan, inferred from ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Heki, Kosuke

    2006-07-01

    The Japanese dense array of Global Positioning System recorded ionospheric disturbances as changes in Total Electron Content ~12 minutes after the September 1 2004 eruption of the Asama Volcano, Central Japan. The disturbance had a period of one and a quarter minutes and propagated as fast as ~1.1 km/s, suggesting its origin as the acoustic wave generated by the explosion. By comparing the disturbance amplitudes with those by a surface mine blast with a known energy, the overall Asama explosion energy is inferred to be about 2 × 1014 J.

  16. Holocene recurrent explosive activity at Chimborazo volcano (Ecuador)

    NASA Astrophysics Data System (ADS)

    Barba, Diego; Robin, Claude; Samaniego, Pablo; Eissen, Jean-Philippe

    2008-09-01

    Ice-capped Chimborazo is one of the large composite Ecuadorian volcanoes whose recent eruptive activity is poorly known. This paper presents the characteristics and the ages of a newly discovered Holocene sequence of pyroclastic deposits on the east and north sides of the cone. Lying upon a moraine of the Late-Glacial period, the most complete section of ~ 4.5 m in thickness is located 5 km from the present summit crater. It consists of seven massive or diffusely stratified ash flow layers and four fallout layers interbedded with seven paleosoils. Based on field study, most flow deposits were assessed as surge layers, and six radiocarbon analyses obtained from charcoal fragments and paleosoils indicate that eruptions occurred at quite regular intervals between about 8000 and 1000 years ago. The first two and most potent events generated thick lahars over the north and west flanks of the cone. Surface textures of volcanic clasts were analysed by scanning electron microscopy. Blocky and blocky/fluidal vitric clasts indicate fragmentation during vulcanian explosions of a quite solidified shallow magma body. In addition, aggregates either cemented at a cooling stage (with surface fluidal textures), or consisting of fine particles (moss-looking aggregates), form a large part of the surge deposits. These characteristics indicate powerful explosions and intense fragmentation due to phreatic water reaching the conduit, probably from the ice-cap. Since the last eruption occurred between the early part of the 5th century (~ AD 420) and the end of the 7th century, these results highlight that Chimborazo is a potentially active volcano. Given its dominating presence over the densely populated Ambato and Riobamba basins, and owing its large ice-cap, Chimborazo should be considered a dangerous volcano.

  17. Aerial monitoring in active mud volcano by UAV technique

    NASA Astrophysics Data System (ADS)

    Pisciotta, Antonino; Capasso, Giorgio; Madonia, Paolo

    2016-04-01

    UAV photogrammetry opens various new applications in the close range domain, combining aerial and terrestrial photogrammetry, but also introduces low-cost alternatives to the classical manned aerial photogrammetry. Between 2014 and 2015 tree aerial surveys have been carried out. Using a quadrotor drone, equipped with a compact camera, it was possible to generate high resolution elevation models and orthoimages of The "Salinelle", an active mud volcanoes area, located in territory of Paternò (South Italy). The main risks are related to the damages produced by paroxysmal events. Mud volcanoes show different cyclic phases of activity, including catastrophic events and periods of relative quiescence characterized by moderate activity. Ejected materials often are a mud slurry of fine solids suspended in liquids which may include water and hydrocarbon fluids, the bulk of released gases are carbon dioxide, with some methane and nitrogen, usually pond-shaped of variable dimension (from centimeters to meters in diameter). The scope of the presented work is the performance evaluation of a UAV system that was built to rapidly and autonomously acquire mobile three-dimensional (3D) mapping data in a volcanic monitoring scenario.

  18. Remote sensing for active volcano monitoring in Barren Island, India

    SciTech Connect

    Bhattacharya, A.; Reddy, C.S.S.; Srivastav, S.K. )

    1993-08-01

    The Barren Island Volcano, situated in the Andaman Sea of the Bay of Bengal, erupted recently (March, 1991) after a prolonged period of quiescence of about 188 years. This resumed activity coincides with similar outbreaks in the Philippines and Japan, which are located in an identical tectonic environment. This study addresses (1) remote sensing temporal monitoring of the volcanic activity, (2) detecting hot lava and measuring its pixel-integrated and subpixel temperatures, and (3) the importance of SWIR bands for high temperature volcanic feature detection. Seven sets of TM data acquired continuously from 3 March 1991 to 8 July 1991 have been analyzed. It is concluded that detectable pre-eruption warming took place around 25 March 1991 and volcanic activity started on 1 April 1991. It is observed that high temperature features, such as an erupting volcano, can register emitted thermal radiance in SWIR bands. Calculation of pixel-integrated and sub-pixel temperatures related to volcanic vents has been made, using the dual-band method. 6 refs.

  19. International Global Atmospheric Chemistry Programme global emissions inventory activity: Sulfur emissions from volcanoes, current status

    SciTech Connect

    Benkovitz, C.M.

    1995-07-01

    Sulfur emissions from volcanoes are located in areas of volcanic activity, are extremely variable in time, and can be released anywhere from ground level to the stratosphere. Previous estimates of global sulfur emissions from all sources by various authors have included estimates for emissions from volcanic activity. In general, these global estimates of sulfur emissions from volcanoes are given as global totals for an ``average`` year. A project has been initiated at Brookhaven National Laboratory to compile inventories of sulfur emissions from volcanoes. In order to complement the GEIA inventories of anthropogenic sulfur emissions, which represent conditions circa specific years, sulfur emissions from volcanoes are being estimated for the years 1985 and 1990.

  20. Satellite observations of Lava Lake activity at Nyiragongo volcano, ex-Zaire, during the Rwandan refugee crisis.

    PubMed

    Oppenheimer, C

    1998-09-01

    In June 1994 the summit crater of Nyiragongo volcano, located in the Great Lakes region of central Africa, began to fill with new lava, ending nearly 12 years of quiescence. An earlier eruption of the volcano in 1977 had culminated in the catastrophic draining of a lava lake through fissures in the crater wall, feeding highly mobile lava flows which reached the outskirts of Goma and killed more than 70 people. By July 1994, as many as 20,000 Hutu refugees were arriving in Goma every hour, only 18 km south from the summit of Nyiragongo. The exodus brought more than one million people to the camps near the town raising fears of a repeat of the 1977 eruption. This paper examines the role that satellite remote sensing could have played in surveillance of the volcano during this time, and demonstrates the potential for monitoring this and other volcanoes in the future. Images recorded by the spaceborne Advanced Very High Resolution Radiometer (AVHRR)--freely available over the Internet--provide semi-quantitative information on the activity of the volcano. The aim of this paper is to promote the wider use of readily available technologies. PMID:9753815

  1. Catalogue of satellite photography of the active volcanoes of the world

    NASA Technical Reports Server (NTRS)

    Heiken, G.

    1976-01-01

    A catalogue is presented of active volcanoes as viewed from Earth-orbiting satellites. The listing was prepared of photographs, which have been screened for quality, selected from the earth resources technology satellite (ERTS) and Skylab, Apollo and Gemini spacecraft. There is photography of nearly every active volcano in the world; the photographs are particularly useful for regional studies of volcanic fields.

  2. Observing ground surface change series at active volcanoes in Indonesia using backscattering intensity of SAR data

    NASA Astrophysics Data System (ADS)

    Saepuloh, Asep; Trianaputri, Mila Olivia

    2015-04-01

    Indonesia contains 27 active volcanoes passing the West through the East part. Therefore, Indonesia is the most hazard front due to the volcanic activities. To obtain the new precursory signals leading to the eruptions, we applied remote sensing technique to observe ground surface change series at the summit of Sinabung and Kelud volcanoes. Sinabung volcano is located at Karo Region, North Sumatra Province. This volcano is a strato volcano type which is re-activated in August 2010. The eruption continues to the later years by ejecting volcanic products such as lava, pyroclastic flow, and ash fall deposits. This study is targeted to observe ground surface change series at the summit of Sinabung volcano since 2007 to 2011. In addition, we also compared the summit ground surface changes after the eruptions of Kelud volcano in 2007. Kelud volcano is also strato volcano type which is located at East Java, Indonesia. The Synthetic Aperture Radar (SAR) remotely sensed technology makes possible to observe rapidly a wide ground surface changes related to ground surface roughness. Detection series were performed by extracting the backscattering intensity of the Phased Array type L-band Synthetic Aperture Radar (PALSAR) onboard the Advanced Land Observing Satellite (ALOS). The intensity values were then calculated using a Normalized Radar Cross-Section (NRCS). Based on surface roughness criterion at the summit of Sinabung volcano, we could observe the ground surface changes prior to the early eruption in August 2010. The continuous increment of NRCS values showed clearly at window size 3×3 pixel of the summit of Sinabung volcano. The same phenomenon was also detected at the summit of Kelud volcano after the 2007 eruptions. The detected ground surface changes were validated using optical Landsat-8, backscattering intensity ratio for volcanic products detection, and radial component of a tilt-meter data.

  3. A Benthic Invertebrate Survey of Jun Jaegyu Volcano: An active undersea volcano in Antarctic Sound, Antarctica

    NASA Astrophysics Data System (ADS)

    Quinones, G.; Brachfeld, S.; Gorring, M.; Prezant, R. S.; Domack, E.

    2005-12-01

    Jun Jaegyu volcano, an Antarctic submarine volcano, was dredged in May 2004 during cruise 04-04 of the RV Laurence M. Gould to determine rock, sediment composition and marine macroinvertebrate diversity. The objectives of this study are to examine the benthic assemblages and biodiversity present on a young volcano. The volcano is located on the continental shelf of the northeastern Antarctic Peninsula, where recent changes in surface temperature and ice shelf stability have been observed. This volcano was originally swath-mapped during cruise 01-07 of the Research Vessel-Ice Breaker Nathaniel B. Palmer. During LMG04-04 we also studied the volcano using a SCUD video camera, and performed temperature surveys along the flanks and crest. Both the video and the dredge indicate a seafloor surface heavily colonized by benthic organisms. Indications of fairly recent lava flows are given by the absence of marine life on regions of the volcano. The recovered dredge material was sieved, and a total of thirty-three invertebrates were extracted. The compilation of invertebrate community data can subsequently be compared to other benthic invertebrate studies conducted along the peninsula, which can determine the regional similarity of communities over time, their relationship to environmental change and health, if any, and their relationship to geologic processes in Antarctic Sound. Twenty-two rock samples, all slightly weathered and half bearing encrusted organisms, were also analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Except for one conglomerate sample, all are alkali basalts and share similar elemental compositions with fresh, unweathered samples from the volcano. Two of the encrusted basalt samples have significantly different compositions than the rest. We speculate this difference could be due to water loss during sample preparation, loss of organic carbon trapped within the vesicles of the samples and/or elemental uptake by the

  4. 1994 Volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Neal, Christina A.; Doukas, Michael P.; McGimsey, Robert G.

    1995-01-01

    During 1994, the Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, or false alarms at nine volcanic centers-- Mount Sanford, Iliamna, the Katmai group, Kupreanof, Mount Veniaminof, Shishaldin, Makushin, Mount Cleveland and Kanaga (table 1). Of these volcanoes, AVO has a real time, continuously recording seismic network only at Iliamna, which is located in the Cook Inlet area of south-central Alaska (fig. 1). AVO has dial-up access to seismic data from a 5-station network in the general region of the Katmai group of volcanoes. The remaining unmonitored volcanoes are located in sparsely populated areas of the Wrangell Mountains, the Alaska Peninsula, and the Aleutian Islands (fig. 1). For these volcanoes, the AVO monitoring program relies chiefly on receipt of pilot reports, observations of local residents and analysis of satellite imagery.

  5. Linking subsurface to surface degassing at active volcanoes: A thermodynamic model with applications to Erebus volcano

    NASA Astrophysics Data System (ADS)

    Iacovino, Kayla

    2015-12-01

    Volcanic plumbing systems are the pathways through which volatiles are exchanged between the deep Earth and the atmosphere. The interplay of a multitude of processes occurring at various depths in the system dictates the composition and quantity of gas eventually erupted through volcanic vents. Here, a model is presented as a framework for interpreting surface volcanic gas measurements in terms of subsurface degassing processes occurring throughout a volcanic plumbing system. The model considers all possible sources of fluid from multiple depths, including degassing of dissolved volatiles during crystallization and/or decompression as recorded in melt inclusions plus any co-existing fluid phase present in a magma reservoir. The former is achieved by differencing melt inclusion volatile contents between groups of melt inclusions saturated at discrete depths. The latter is calculated using a thermodynamic model, which computes the composition of a C-O-H-S fluid in equilibrium with a melt given a minimum of five thermodynamic parameters commonly known for natural systems (T, P, fO2, either fH2 or one parameter for H2O, and either fS2 or one parameter for CO2). The calculated fluids are thermodynamically decompressed and run through a mixing model, which finds all possible mixtures of subsurface fluid that match the chemistry of surface gas within ±2.0 mol%. The method is applied to Mount Erebus (Antarctica), an active, intraplate volcano whose gas emissions, which emanate from an active phonolitic lava lake, have been well quantified by FTIR, UV spectroscopy, and multi-gas sensors over the last several decades. In addition, a well-characterized suite of lavas and melt inclusions, and petrological interpretations thereof, represent a wealth of knowledge about the shallow, intermediate, and deep parts of the Erebus plumbing system. The model has been used to calculate the compositions of seven C-O-H-S fluids that originate from four distinct regions within the Erebus

  6. Testing a New Method for Imaging Crustal Magma Bodies: A Pilot Study at Newberry Volcano, Central OR

    NASA Astrophysics Data System (ADS)

    Beachly, M. W.; Hooft, E. E.; Toomey, D. R.; Waite, G. P.; Durant, D. T.

    2010-12-01

    Magmatic systems are often imaged using delay time seismic tomography, though a known limitation is that wavefront healing limits the ability of transmitted waves to detect small, low-velocity regions such as magma chambers. Crustal magma chambers have been successfully identified using secondary arrivals, including both P and S wave reflections and conversions. Such secondary phases are often recorded by marine seismic experiments owing to the density and quality of airgun data, which improves the identification of coherent arrivals. In 2008 we conducted a pilot study at Newberry volcano to test a new method of detecting secondary arrivals in a terrestrial setting. Our experimental geometry used a line of densely spaced (~300 m), three-component seismometers to record a shot-of-opportunity from the High Lave Plains Experiment. An ideal study would record several shots, however, data from this single event proves the concept. As part of our study, we also reanalyze all existing seismic data from Newberry volcano to obtain a tomographic image of the velocity structure to 6 km depth. Newberry is a lone shield volcano in central Oregon, located 40 km east of the Cascade axis. Newberry eruptions are silicic within the central caldera and mafic on its periphery suggesting a central silicic magma storage system, possibly located at upper crustal depths. The system may still be active with a recent eruption ~1300 years ago, and a central drill hole temperature of 256° C at only 932 m depth. A low-velocity anomaly previously imaged at 3-5 km beneath the caldera indicates either a magma body or a fractured pluton. Our tomographic study combines our 2008 seismic data with profile and array data collected in the 1980s by the USGS. In total, the inversion includes 16 active sources and 322 receivers yielding 1007 P-wave first arrivals. Beneath the caldera ring faults we image a high-velocity ring-like anomaly extending to 2 km depth. This anomaly is inferred to be near

  7. Hydrothermal System of the Lastarria Volcano (Central Andes) Imaged by Magnetotellurics

    NASA Astrophysics Data System (ADS)

    Diaz, D.

    2015-12-01

    Lazufre volcanic complex, located in the central Andes, is recently undergoing an episode of uplift, conforming one of the most extensive deforming volcanic systems worldwide. Recent works have focused on the subsurface of this volcanic system at different scales, using surface deformation data, seismic noise tomography and magnetotellurics. Here we image the electrical resistivity structure of the Lastarria volcano, one of the most important features in the Lazufre area, using broadband magnetotelluric data at 30 locations around the volcanic edifice. Results from 3-D modeling show a conductive zone at 6 km depth south of the Lastarria volcano interpreted as a magmatic heat source, which is connected to a shallower conductive area beneath the volcanic edifice and its close vicinity. This shallow highly conductive zone fits with geochemical analysis results of thermal fluid discharges, related to fumaroles present in this area, in terms of depth extent and possible temperatures of fluids, and presents also a good correlation with seismic tomography results. The horizontal extension of this shallow conductive zone, related to the hydrothermal system of Lastarria, suggests that it has been draining one of the lagoons in the area (Laguna Azufrera), forming a sulfur rich area which can be observed at the southern side of this lagoon. Joint modeling of the hydrothermal system using magnetotellurics and seismic data is part of the current work.

  8. 10,000 Years of explosive eruptions of Merapi Volcano, Central Java: archaeological and modern implications

    USGS Publications Warehouse

    Newhall, C.G.; Bronto, S.; Alloway, B.; Banks, N.G.; Bahar, I.; Del Marmol, M.A.; Hadisantono, R.D.; Holcomb, R.T.; McGeehin, J.; Miksic, J.N.; Rubin, M.; Sayudi, S.D.; Sukhyar, R.; Andreastuti, S.; Tilling, R.I.; Torley, R.; Trimble, D.; Wirakusumah, A.D.

    2000-01-01

    Stratigraphy and radiocarbon dating of pyroclastic deposits at Merapi Volcano, Central Java, reveals ~10,000 years of explosive eruptions. Highlights include: (1) Construction of an Old Merapi stratovolcano to the height of the present cone or slightly higher. Our oldest age for an explosive eruption is 9630±60 14C y B.P.; construction of Old Merapi certainly began earlier. (2) Collapse(s) of Old Merapi that left a somma rim high on its eastern slope and sent one or more debris avalanche(s) down its southern and western flanks. Impoundment of Kali Progo to form an early Lake Borobudur at ~3400 14C y B.P. hints at a possible early collapse of Merapi. The latest somma-forming collapse occurred ~1900 14C y B.P. The current cone, New Merapi, began to grow soon thereafter. (3) Several large and many small Buddhist and Hindu temples were constructed in Central Java between 732 and ~900 A.D. (roughly, 1400-1000 14C y B.P.). Explosive Merapi eruptions occurred before, during and after temple construction. Some temples were destroyed and (or) buried soon after their construction, and we suspect that this destruction contributed to an abrupt shift of power and organized society to East Java in 928 A.D. Other temples sites, though, were occupied by "caretakers" for several centuries longer. (4) A partial collapse of New Merapi occurred 14C y B.P. Eruptions ~700-800 14C y B.P. (12-14th century A.D.) deposited ash on the floors of (still-occupied?) Candi Sambisari and Candi Kedulan. We speculate but cannot prove that these eruptions were triggered by (the same?) partial collapse of New Merapi, and that the eruptions, in turn, ended "caretaker" occupation at Candi Sambisari and Candi Kedulan. A new or raised Lake Borobudur also existed during part or all of the 12-14th centuries, probably impounded by deposits from Merapi. (5) Relatively benign lava-dome extrusion and dome-collapse pyroclastic flows have dominated activity of the 20th century, but explosive eruptions much

  9. Evolution of Deformation Studies on Active Hawaiian Volcanoes

    USGS Publications Warehouse

    Decker, Robert; Okamura, Arnold; Miklius, Asta; Poland, Michael

    2008-01-01

    Everything responds to pressure, even rocks. Deformation studies involve measuring and interpreting the changes in elevations and horizontal positions of the land surface or sea floor. These studies are variously referred to as geodetic changes or ground-surface deformations and are sometimes indexed under the general heading of geodesy. Deformation studies have been particularly useful on active volcanoes and in active tectonic areas. A great amount of time and energy has been spent on measuring geodetic changes on Kilauea and Mauna Loa Volcanoes in Hawai`i. These changes include the build-up of the surface by the piling up and ponding of lava flows, the changes in the surface caused by erosion, and the uplift, subsidence, and horizontal displacements of the surface caused by internal processes acting beneath the surface. It is these latter changes that are the principal concern of this review. A complete and objective review of deformation studies on active Hawaiian volcanoes would take many volumes. Instead, we attempt to follow the evolution of the most significant observations and interpretations in a roughly chronological way. It is correct to say that this is a subjective review. We have spent years measuring and recording deformation changes on these great volcanoes and more years trying to understand what makes these changes occur. We attempt to make this a balanced as well as a subjective review; the references are also selective rather than exhaustive. Geodetic changes caused by internal geologic processes vary in magnitude from the nearly infinitesimal - one micron or less, to the very large - hundreds of meters. Their apparent causes also are varied and include changes in material properties and composition, atmospheric pressure, tidal stress, thermal stress, subsurface-fluid pressure (including magma pressure, magma intrusion, or magma removal), gravity, and tectonic stress. Deformation is measured in units of strain or displacement. For example, tilt

  10. An active seismic experiment at Tenerife Island (Canary Island, Spain): Imaging an active volcano edifice

    NASA Astrophysics Data System (ADS)

    Garcia-Yeguas, A.; Ibañez, J. M.; Rietbrock, A.; Tom-Teidevs, G.

    2008-12-01

    An active seismic experiment to study the internal structure of Teide Volcano was carried out on Tenerife, a volcanic island in Spain's Canary Islands. The main objective of the TOM-TEIDEVS experiment is to obtain a 3-dimensional structural image of Teide Volcano using seismic tomography and seismic reflection/refraction imaging techniques. At present, knowledge of the deeper structure of Teide and Tenerife is very limited, with proposed structural models mainly based on sparse geophysical and geological data. This multinational experiment which involves institutes from Spain, Italy, the United Kingdom, Ireland, and Mexico will generate a unique high resolution structural image of the active volcano edifice and will further our understanding of volcanic processes.

  11. Recent Seismic and Geodetic Activity at Multiple Volcanoes in the Ecuadorean Andes

    NASA Astrophysics Data System (ADS)

    Hernandez, S.; Ruiz, M. C.; McCausland, W. A.; Prejean, S. G.; Mothes, P. A.; Bell, A. F.; Hidalgo, S.; Barrington, C.; Yepez, M.; Aguaiza, S.; Plain, M.

    2015-12-01

    The state of volcanic activity often fluctuates between periods of repose and unrest. The transition time between a period of repose and unrest, or vice versa for an open system, can occur within a matter of hours or days. Because of this short time scale, real-time seismic and geodetic (e.g. tiltmeter, GPS) monitoring networks are crucial for characterizing the state of activity of a volcano. In the Ecuadorean Andes, 5 volcanoes demonstrate long-term (Tungurahua, Reventador, and Guagua Pichincha) or recently reactivated (Cotopaxi, Chiles-Cerro Negro) seismic and geodetic activity. The Instituto Geofisico regularly characterizes volcano seismicity into long period, very long period, volcano-tectonic, and tremor events. Significant recent changes at these volcanoes include: rigorous reactivation of glacier-capped Cotopaxi, drumbeat seismicity absent a dome extrusion at Tungurahua, and regularly reoccurring (~7 day recurrence interval), shallow seismic swarms at Guagua Pichincha. These volcanoes locate along both the Western and Eastern Cordillera of the Ecuadorean Andes and, where data are available, manifest important variations in chemical composition, daily gas flux, and surficial deformation. We summarize the long-term geophysical parameters measured at each volcano and place recent changes in each parameter in a larger magmatic and hydrothermal context. All of the studied volcanoes present significant societal hazards to local and regional communities.

  12. Seismicity study of volcano-tectonic in and around Tangkuban Parahu active volcano in West Java region, Indonesia

    NASA Astrophysics Data System (ADS)

    Ry, Rexha V.; Priyono, A.; Nugraha, A. D.; Basuki, A.

    2016-05-01

    Tangkuban Parahu is one of the active volcano in Indonesia located about 15 km northern part of Bandung city. The objective of this study is to investigate the seismic activity in the time periods of January 2013 to December 2013. First, we identified seismic events induced by volcano-tectonic activities. These micro-earthquake events were identified as having difference of P-wave and S-wave arrival times less than three seconds. Then, we constrained its location of hypocenter to locate the source of the activities. Hypocenter determination was performed using adaptive simulated annealing method. Using these results, seismic tomographic inversions were conducted to image the three-dimensional velocity structure of Vp, Vs, and the Vp/Vs ratio. In this study, 278 micro-earthquake events have been identified and located. Distribution of hypocenters around Tangkuban Parahu volcano forms an alignment structure and may be related to the stress induced by magma below, also movement of shallow magma below Domas Crater. Our preliminary tomographic inversion results indicate the presences of low Vp, high Vs, and low Vp/Vs ratio that associate to accumulated young volcanic eruption products and hot material zones.

  13. Volcano-stratigraphy and Petrography of the Hasandaǧ Volcanites (Central Anatolia)

    NASA Astrophysics Data System (ADS)

    Zeynep Çalışkanoǧlu, Ayşe; Ünal, Alp; Karadaǧ, Elif; Altunkaynak, Şafak; Görür, Naci

    2016-04-01

    The Hasandaǧ stratovolcano is one of the crucial volcanos within the Cappadocian Volcanic Complex, located in Central Anatolia, Turkey. In Quaternary, it produced various types of volcanic rocks including a variety of lava flows, domes and associated pyroclastic and volcanoclastic rocks. In this study, volcano-stratigraphy and petrography of the volcanic rocks which forms the SE flank of the Hasandaǧ stratovolcano will be presented. The early pyroclastic products associated with plinian-subplinian eruptions cover large areas with different thickness in the region. Felsic pyroclastic rocks are dominant and represented by ash, pumice and pumice-block tuffs and accretionary lapilli tuffs/breccias. Pyroclastic deposits are present as thin layers of reworked tuffs intercalated with sedimentary rocks (mudstone and marl) at the bottom of the volcanic sequence. They interfinger with pyroclastic flow deposits dominated by welded tuff and ignimbrite succession towards the upper parts of the sequence. Andesite- basaltic andesite and basaltic trachy-andesite lavas form the most common lava phase in the region and overlie the pyroclastic succession. At the upper parts of the volcanic succession, basaltic dykes and associated pyroclastic rocks are observed. The youngest member of the volcanic association is represented by andesitic-basaltic andesitic dykes which were injected into basaltic lavas and associated proclastic rocks. The areal distribution of the volcanic rocks in the SE flank of the Hasandaǧ stratovolcano indicates that they were erupted from a number of vents which set parallel to the NW-SE trending major fault systems of Central Anatolia (eg. The Salt Lake Fault). Petrographic investigations indicate that, all lava samples display several textures reflecting disequilibrium crystallization such as different stage of the plagioclase crystallization, sieve texture in plagioclases, clinopyroxene crystals mantled by hornblende (corona texture) and reaction textures

  14. 2013 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2015-01-01

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

  15. Active Source Tomography of Stromboli Volcano (Italy): Results From the 2006 Seismic Experiment.

    NASA Astrophysics Data System (ADS)

    Zuccarello, L.; Patanè, D.; Cocina, O.; Castellano, M.; Sgroi, T.; Favali, P.; de Gori, P.

    2008-12-01

    Stromboli island, located in the Southern Tyrrhenian sea, is the emerged part (about 900 m a.s.l.) of a 3km-high strato-volcano. Its persistent Strombolian activity, documented for over 2000 years, is sometimes interrupted by lava effusions or major explosions. Despite the amount of recent published geophysical studies aimed to clarifying eruption dynamics, the spatial extend and geometrical characteristics of the plumbing system remain poorly understood. In fact, the knowledge of the inner structure and the zones of magma storage is limited to the upper few hundreds meters of the volcanic edifice and P- and S-waves velocity models are available only in restricted areas. In order to obtain a more suitable internal structural and velocity models of the volcano, from 25 November to 2 December 2006, a seismic tomography experiment through active seismics using air-gun sources was carried out and the final Vp model is here presented. The data has been inverted for the Vp structure by using the code Simulps13q, considering a 3D grid of nodes spaced 0.5 km down to 2 km depth, beneath the central part of volcano. The results show a relatively high velocity zones located both in the inner part of the volcanic structure, at about 1km b.s.l. and in the last 200-300 m a.s.l. in correspondence with the volcanic conduit. Slower zones were located around the summit craters in agreement with volcanological and petrological informations for the area. The relatively high velocity zones could suggest the presence of intrusive bodies related to the plumbing system.

  16. "MERAPIDATA": New Petrologic and Geochemical Database of the Merapi Volcano, Central Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Borisova, A. Y.; Martel, C.; Pratomo, I.; Toutain, J.; Sumarti, S.; Surono, S.

    2011-12-01

    Petrologic and geochemical databases of erupted products are critical for monitoring and predicting the evolution of active volcanoes. To monitor the activity of one of the most dangerous volcanoes in the world, Merapi Volcano in Indonesia, in the framework of the new instrumental site VELI (Volcans Explosifs - Laboratoires Indonésiens labelled by INSU in 2009 in France), we generated "MERAPIDATA", a complete database of available petrologic and geochemical data published in the literature on pyroclastic flows, tephra, lavas and xenoliths coupled with the exact ages of historical flows [1] or estimated ages based on 14C geochronology [2]. "MERAPIDATA" permits to access complete petrologic, geochemical, and geochronological information (e.g., major, trace element and Sr-Nd-Pb-O isotopic composition of the bulk volcanic rocks, xenoliths, minerals and glasses; textural information; type of eruption; classification) of a given volcanic product or series. In addition to ~300 published volcanic products, new data on 2 pyroclastic flows, 1 tephra and 4 ash samples collected on northern and western slopes of the volcano in October and November 2010 during subplinian type eruption have been added to "MERAPIDATA". The 2010 ash sample chemistry allows classifying them as high-K basaltic andesite. The ash samples demonstrate major and trace element compositions typical for the high-K series. For the first time, we obtained complete data on the Merapi ash samples which characterized by low L.O.I. ≤ 0.58 wt%, CO2total ≤ 0.05 wt%, H2Ototal = 0.3 - 0.5 wt%, Stotal ≤ 0.13 wt% and moderate Cl (550 - 1120 ppm) contents. The ash-leachates produced by leaching experiments demonstrate constant F/Cl ratios (0.05 ± 0.01) and Ca-Na-K enrichment (Ca/Na= 3 - 7, Na/K = 1 - 5). Sr-Nd-Pb-O isotopic analyses on the 2010 Merapi products are in progress. New petrologic (e.g., melt and fluid inclusion data, T - P - fO2 - aH2O - aCO2) and geochemical (e.g., volatile, major, trace element and

  17. Identifying hazard parameter to develop quantitative and dynamic hazard map of an active volcano in Indonesia

    NASA Astrophysics Data System (ADS)

    Suminar, Wulan; Saepuloh, Asep; Meilano, Irwan

    2016-05-01

    Analysis of hazard assessment to active volcanoes is crucial for risk management. The hazard map of volcano provides information to decision makers and communities before, during, and after volcanic crisis. The rapid and accurate hazard assessment, especially to an active volcano is necessary to be developed for better mitigation on the time of volcanic crises in Indonesia. In this paper, we identified the hazard parameters to develop quantitative and dynamic hazard map of an active volcano. The Guntur volcano in Garut Region, West Java, Indonesia was selected as study area due population are resided adjacent to active volcanoes. The development of infrastructures, especially related to tourism at the eastern flank from the Summit, are growing rapidly. The remote sensing and field investigation approaches were used to obtain hazard parameters spatially. We developed a quantitative and dynamic algorithm to map spatially hazard potential of volcano based on index overlay technique. There were identified five volcano hazard parameters based on Landsat 8 and ASTER imageries: volcanic products including pyroclastic fallout, pyroclastic flows, lava and lahar, slope topography, surface brightness temperature, and vegetation density. Following this proposed technique, the hazard parameters were extracted, indexed, and calculated to produce spatial hazard values at and around Guntur Volcano. Based on this method, the hazard potential of low vegetation density is higher than high vegetation density. Furthermore, the slope topography, surface brightness temperature, and fragmental volcanic product such as pyroclastics influenced to the spatial hazard value significantly. Further study to this proposed approach will be aimed for effective and efficient analyses of volcano risk assessment.

  18. Embedded ARM system for volcano monitoring in remote areas: application to the active volcano on Deception Island (Antarctica).

    PubMed

    Peci, Luis Miguel; Berrocoso, Manuel; Fernández-Ros, Alberto; García, Alicia; Marrero, José Manuel; Ortiz, Ramón

    2014-01-01

    This paper describes the development of a multi-parameter system for monitoring volcanic activity. The system permits the remote access and the connection of several modules in a network. An embedded ARM™ processor has been used, allowing a great flexibility in hardware configuration. The use of a complete Linux solution (Debian™) as Operating System permits a quick, easy application development to control sensors and communications. This provides all the capabilities required and great stability with relatively low energy consumption. The cost of the components and applications development is low since they are widely used in different fields. Sensors and commercial modules have been combined with other self-developed modules. The Modular Volcano Monitoring System (MVMS) described has been deployed on the active Deception Island (Antarctica) volcano, within the Spanish Antarctic Program, and has proved successful for monitoring the volcano, with proven reliability and efficient operation under extreme conditions. In another context, i.e., the recent volcanic activity on El Hierro Island (Canary Islands) in 2011, this technology has been used for the seismic equipment and GPS systems deployed, thus showing its efficiency in the monitoring of a volcanic crisis. PMID:24451461

  19. Embedded ARM System for Volcano Monitoring in Remote Areas: Application to the Active Volcano on Deception Island (Antarctica)

    PubMed Central

    Peci, Luis Miguel; Berrocoso, Manuel; Fernández-Ros, Alberto; García, Alicia; Marrero, José Manuel; Ortiz, Ramón

    2014-01-01

    This paper describes the development of a multi-parameter system for monitoring volcanic activity. The system permits the remote access and the connection of several modules in a network. An embedded ARM™™ processor has been used, allowing a great flexibility in hardware configuration. The use of a complete Linux solution (Debian™) as Operating System permits a quick, easy application development to control sensors and communications. This provides all the capabilities required and great stability with relatively low energy consumption. The cost of the components and applications development is low since they are widely used in different fields. Sensors and commercial modules have been combined with other self-developed modules. The Modular Volcano Monitoring System (MVMS) described has been deployed on the active Deception Island (Antarctica) volcano, within the Spanish Antarctic Program, and has proved successful for monitoring the volcano, with proven reliability and efficient operation under extreme conditions. In another context, i.e., the recent volcanic activity on El Hierro Island (Canary Islands) in 2011, this technology has been used for the seismic equipment and GPS systems deployed, thus showing its efficiency in the monitoring of a volcanic crisis. PMID:24451461

  20. The ongoing dome emplacement and destruction cyclic process at Popocatépetl volcano, Central Mexico

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    The ongoing eruptive activity of Popocatépetl volcano has been characterized by emplacement and subsequent destruction of a succession of lava domes. Between the onset of the current eruption in 1994 and the time of this submission, 38 episodes of lava dome formation and removal have been identified. Each dome has showed particular features related to the magma extrusion process. Among other manifestations, dome-emplacement events have been usually accompanied by relatively low-intensity, protracted explosions referred to as exhalations. After variable times of residence, emplacements have ended in partial or total destruction of the domes by strong vulcanian explosions that produced sizeable ash plumes, with most of them also ejecting incandescent debris onto the volcano flanks. Here, we present a detailed account for the observed activity related to the domes' growth and destruction, related seismic monitoring signals, and morphological features of the domes based on 19 years of visual observations and image analysis. We then discuss a model for the process of dome growth and destruction and its hazard implications.

  1. Self-potential Anomalies Around the Earthquake Swarm Area in the Southeastern Flank of Ontake Volcano, Central Japan

    NASA Astrophysics Data System (ADS)

    Yoshimura, R.; Yamazaki, K.; Okada, Y.; Oshiman, N.

    2006-12-01

    Ontake Volcano is located in the southern end of the Norikura Volcanic Chain, central Japan, close to the junction of the Izu Bonin and Mariana and Southwestern Japan volcanic arcs. It is almost conical and made of andesite. Earthquake swarm activity has been continuously observed around the southeastern flank of Mt. Ontake since 1976. A phreatic explosion occurred in 1979 at a fissure on the southwestern slope of the Kengamine, the main peak of Mt. Ontake. And a large earthquake with the depth about 2 km and a magnitude of 6.8 occurred in 1984 in the southeastern flank of the volcano. Recently, Kimata et al. (2004) revealed uplift ground deformation above the earthquake swarm area by using repeated leveling. Furthermore, Magnetotelluric soundings estimated a low resistivity region with the depth about 2km beneath the uplift area [Kasaya et al., 2002]. In order to investigate a relationship between tectonic movements and subsurface low resistivity zone, we carried out self-potential(SP) measurements from 2003 and 2006 around the focal region of the 1984 Earthquake and the summit area of Mt. Ontake. The equipment for measuring surface self-potentials consists of a pair of non-polarizing copper-copper sulfate/silver-silver chloride electrodes, an insulated connecting conductor cable, and a high input impedance digital multimeter. In this survey, profiles totaling to about 90km length (982 sites) were made, with an average measurement interval of 100m. Two distinctive SP features are found around the active earthquake cluster and inside of the aseismic area of southeastern flank of Mt. Ontake. In this presentation, we will report a detail of SP measurements and results.

  2. Late-stage summit activity of Martian shield volcanoes

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, P. J.

    1982-01-01

    The preservation of morphologically fresh lava flows which pre-date the most recent episodes of caldera collapse at the summits of Ascraeus, Arsia and Olympus Montes indicates that explosive eruptions were not associated with this stage of Tharsis shield volcanism. The existence of resurfaced floor segments, complex wrinkle ridges, and lava terraces within the summit craters suggests that lava lakes comprised the dominant form of the intra-caldera activity. Multiple collapse episodes on Ascraeus and Olympus Montes are indicated by the nested summit craters. The most plausible cause of caldera collapse appears to be large-scale sub-terminal effusive activity, which is corroborated by the previously recognized existence of large lava flows on the flanks of these volcanoes. Due to the implied sequence of large-scale explosive (silicic) volcanism followed by effusive (basaltic) activity, it appears highly unlikely that ignimbrites or other forms of pyroclastic flows (previously proposed as possible deposits within the Olympus Mons aureole material) were ever erupted from the Tharsis Montes.

  3. Gas flux measurements of episodic bimodal eruptive activity at Karymsky volcano (Kamchatka, Russia)

    NASA Astrophysics Data System (ADS)

    Arellano, S.; Galle, B.; Melnikov, D.

    2012-04-01

    Volcanoes of intermediate magmatic composition commonly exhibit episodes of intermittent gas and ash emission of variable duration. Due to the multiple conditions present at each system, different mechanisms have been proposed to account for the observed activity, and without key measurements at hand, a definite understanding of the situation might not be singled out. Karymsky, the most active volcano of Central Kamchatka, has presented a remarkably stable pattern of bimodal eruption since a few weeks after its violent reactivation in 1996. Periods of quasi-periodic explosive emissions with typical recurrence intervals of 3-10 min are alternated with episodes of semi-continuous discharge which intensity has a typical modulation at a frequency of 1 Hz. Geophysical studies at Karymsky have identified the main visual, seismic and acoustic features of these two eruption modalities. From these observations, the time scales of the processes have been defined and relevant models have been formulated, according to which the two modes are controlled by the rheological properties of an intruding gas-saturated magma batch and a shallow gas-depleted magma plug. Explosions are explained as the consequence of the formation of temporary sealing, overpressure buildup and vent clearance. Clearly, direct measurements of the gas emission rate are the key parameter to test such models. In this work, we report on the results of a field campaign for SO2 gas measurements carried out at Karymsky during 10-14 September 2011. We deployed 2 NOVAC-type, scanning DOAS systems as well as 1 rapid wide-Field of View mini-DOAS plume tracker. With this setup, we derived time-resolved SO2 flux, plume height, direction and speed, and detected pulses of increasing emission with high temporal resolution. We observed phases of explosive and quiescent degassing with variable amounts of ash emission and detected intensity changes of the associated acoustic signals. The repose time intervals between these

  4. Chikurachki Volcano

    Atmospheric Science Data Center

    2013-04-16

    ... plume from the April 22, 2003, eruption of the Chikurachki volcano is portrayed in these views from the Multi-angle Imaging ... the volcanically active Kuril Island group, the Chikurachki volcano is an active stratovolcano on Russia's Paramushir Island (just south of ...

  5. Observations of Active Volcanoes Using the EO-1 Satellite

    NASA Astrophysics Data System (ADS)

    Flynn, L. P.; Harris, A. J.; Wright, R.; Oppenheimer, C.; Geschwind, L. R.; Donegan, S.; Garbeil, H.

    2001-12-01

    Previous satellite observations of active volcanoes have been hampered by instruments that are primarily designed to measure surface reflectance of the Earth's vegetation. Sensors detecting radiation in the near-IR and IR are frequently saturated by highly radiant active volcanic features. Two satellite instruments, Hyperion and the Advanced Land Imager (ALI) on the Earth Observing -1 (EO-1) offer a means to circumvent saturation issues. Hyperion is a hyperspectral instrument that collects data in 242 narrow spectral bands between 0.4 and 2.5 microns and produces images that are 7.5 km x 100 km. For each 30m x 30m pixel, accurate atmospheric corrections and multiple component thermal models for lava flows can be generated. ALI is a Landsat-like instrument having 10 spectral bands at 0.4 - 2.35 microns. One of these, the 1.2 micron band, is sensitive to high temperature thermal anomalies such as overturning lava lakes and open lava channels. ALI also has a 10-m panchromtic band that allows for greater detailed mapping of volcanic features. ALI and Hyperion analyses for Erta Ale (Ethiopia), Mt. Etna (Sicily), Santiaguito (Guatemala), Popocatepetl (Mexico), and Mayon (Philippines) will be presented. While distribution of these data sets is limited to the EO-1 Science Team, the future of NASA's high spatial resolution terrestrial observation program will likely be based on a hybrid of these EO-1 sensors.

  6. Virtual Investigations of an Active Deep Sea Volcano

    NASA Astrophysics Data System (ADS)

    Sautter, L.; Taylor, M. M.; Fundis, A.; Kelley, D. S.; Elend, M.

    2013-12-01

    Axial Seamount, located on the Juan de Fuca spreading ridge 300 miles off the Oregon coast, is an active volcano whose summit caldera lies 1500 m beneath the sea surface. Ongoing construction of the Regional Scale Nodes (RSN) cabled observatory by the University of Washington (funded by the NSF Ocean Observatories Initiative) has allowed for exploration of recent lava flows and active hydrothermal vents using HD video mounted on the ROVs, ROPOS and JASON II. College level oceanography/marine geology online laboratory exercises referred to as Online Concept Modules (OCMs) have been created using video and video frame-captured mosaics to promote skill development for characterizing and quantifying deep sea environments. Students proceed at their own pace through a sequence of short movies with which they (a) gain background knowledge, (b) learn skills to identify and classify features or biota within a targeted environment, (c) practice these skills, and (d) use their knowledge and skills to make interpretations regarding the environment. Part (d) serves as the necessary assessment component of the laboratory exercise. Two Axial Seamount-focused OCMs will be presented: 1) Lava Flow Characterization: Identifying a Suitable Cable Route, and 2) Assessing Hydrothermal Vent Communities: Comparisons Among Multiple Sulfide Chimneys.

  7. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system

    PubMed Central

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N.; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-01-01

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report 3He/4He measurements in CO2–dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a 3He/4He signature of at least 7.0 Ra (being Ra the 3He/4He ratio of atmospheric He equal to 1.39×10−6), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like 3He/4He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano. PMID:27311383

  8. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system

    NASA Astrophysics Data System (ADS)

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N.; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-06-01

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report 3He/4He measurements in CO2–dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a 3He/4He signature of at least 7.0 Ra (being Ra the 3He/4He ratio of atmospheric He equal to 1.39×10‑6), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like 3He/4He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano.

  9. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system.

    PubMed

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-01-01

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report (3)He/(4)He measurements in CO2-dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a (3)He/(4)He signature of at least 7.0 Ra (being Ra the (3)He/(4)He ratio of atmospheric He equal to 1.39×10(-6)), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like (3)He/(4)He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano. PMID:27311383

  10. Potentially active volcanoes of Peru - Observations using Landsat Thematic Mapper and Space Shuttle imagery

    NASA Technical Reports Server (NTRS)

    De Silva, S. L.; Francis, P. W.

    1990-01-01

    A synoptic study of the volcanoes of southern Peru (14-17 deg S), the northernmost part of the Central Volcanic Zone (CVZ 14-28 deg S) of the Andes, was conducted on the basis of Landsat TM images and color photography. The volcanoes were classified and their relative ages determined using subtle glacial-morphological features. Eight of them were postulated as potentially active. These are located in a narrow volcanic zone which probably reflects a steep dip of the Nazca plate through the zone of magma generation. The break in the trend of the volcanic arc possibly reflects the complexity of the crustal stress field above a major segment boundary in the subducting plate. There are also fields of mafic monogenetic centers in this region. In comparison with the southern part of the CVZ, the general paucity of older volcanic edifices north of 17 deg S suggested a more recent onset of volcanism, a possible result of the oblique subduction of the Nazca ridge and the consequent northward migration of its intersection with the Peru-Chile trench. This, together with the lack of any large silicic caldera systems and youthful dacite domes, suggested that there are real differences in the volcanic evolution of the two parts of the CVZ.

  11. Geology and preliminary [sup 40]Ar/[sup 39]Ar geochronology of the Sliderock Mountain volcano, south-central Montana

    SciTech Connect

    Du Bray, E.A.; Harlan, S.S. )

    1993-04-01

    The Sliderock Mountain Volcano is a deeply eroded, Upper Cretaceous basaltic andesite stratovolcano complex located along the northeastern margin of the Laramide Beartooth uplift of south-central Montana. Historically, these rocks have been included in the Livingston Group and correlated with Upper Cretaceous, dominantly epiclastic sedimentary rocks of the Livingston Group in the Crazy Mountains Basin. Recent geologic mapping has identified several map units including: basaltic andesite of Derby Ridge (lava flows, and minor interbedded pyroclastic flows including welded tuff, block and ash flows, and lahars); volcaniclastic sedimentary rocks; lahar deposits; dioritic plutons and sills (including the diorite of Sliderock Mountain); basaltic andesite lavas; and basaltic trachyandesite dikes. Stratigraphic relations indicate that initial volcanic activity was dominated by eruption of the basaltic andesite of Derby Ridge. Cross-cutting relations indicate that dioritic plutons and sills are younger than the basaltic andesite of Derby Ridge and the lahars but age relations with the second set of basaltic andesite lavas are indeterminate. The volcanic and dike rocks of the stratovolcano are cpx-plag rocks, characterized by limited compositional variation, whereas intrusive rocks are hbl-plag rocks whose compositions are principally that of diorite, but range to granite. [sup 40]Ar/[sup 39]Ar isotopic analysis of hornblende from the Lodgepole intrusion, a hypabyssal intrusion that may constitute part of the volcano's solidified magma chamber, gives an age of 76.2 [+-] 0.3 Ma (1[sigma]), significantly younger than a previously reported K-Ar biotite age of 82 Ma. [sup 40]Ar/[sup 39]Ar analyses of sericite from weakly mineralized Au-bearing quartz veins hosted by the diorite of Sliderock Mountain give slightly younger isochron ages of 73--74 Ma indicating that gold mineralization is probably associated with the late stages of cooling of the Sliderock Mountain magma system.

  12. Historical eruptions of Merapi Volcano, Central Java, Indonesia, 1768-1998

    USGS Publications Warehouse

    Voight, B.; Constantine, E.K.; Siswowidjoyo, S.; Torley, R.

    2000-01-01

    Information on Merapi eruptive activity is scattered and much is remotely located. A concise and well-documented summary of this activity has been long needed to assist researchers and hazard-mitigation efforts, and the aim of this paper is to synthesize information from the mid-1700s to the present. A descriptive chronology is given, with an abbreviated chronology in a table that summarizes events by year, assigns preliminary Volcanic Explosivity Index (VEI) ratings and Hartmann classifications, and provides key references. The history of volcano monitoring is also outlined. The study reveals that a major difference in eruption style exists between the twentieth and nineteenth centuries, although the periodicity between larger events seems about the same. During the twentieth century, activity has comprised mainly the effusive growth of viscous lava domes and lava tongues, with occasional gravitational collapses of parts of oversteepened domes to produce the nue??es ardentes - commonly defined as "Merapi-type". In the 1800s, however, explosive eruptions of relatively large size occurred (to VEI 4), and some associated "fountain-collapse" nue??es ardentes were larger and farther reaching than any produced in the twentieth century. These events may also be regarded as typical eruptions for Merapi. The nineteenth century activity is consistent with the long-term pattern of one relatively large event every one or two centuries, based on the long-term eruptive record deduced by others from volcanic stratigraphy. It is uncertain whether or not a "recurrence-time" model continues to apply to Merapi, but if so, Merapi could soon be due for another large event and its occurrence with only modest (or inadequately appreciated) precursors could lead to a disaster unprecedented in Merapi's history because the area around the volcano is now much more densely populated. ?? 2000 Elsevier Science B.V. All rights reserved.

  13. Shallow outgassing changes disrupt steady lava lake activity, Kilauea Volcano

    NASA Astrophysics Data System (ADS)

    Patrick, M. R.; Orr, T. R.; Swanson, D. A.; Lev, E.

    2015-12-01

    Persistent lava lakes are a testament to sustained magma supply and outgassing in basaltic systems, and the surface activity of lava lakes has been used to infer processes in the underlying magmatic system. At Kilauea Volcano, Hawai`i, the lava lake in Halema`uma`u Crater has been closely studied for several years with webcam imagery, geophysical, petrological and gas emission techniques. The lava lake in Halema`uma`u is now the second largest on Earth, and provides an unprecedented opportunity for detailed observations of lava lake outgassing processes. We observe that steady activity is characterized by continuous southward motion of the lake's surface and slow changes in lava level, seismic tremor and gas emissions. This normal, steady activity can be abruptly interrupted by the appearance of spattering - sometimes triggered by rockfalls - on the lake surface, which abruptly shifts the lake surface motion, lava level and gas emissions to a more variable, unstable regime. The lake commonly alternates between this a) normal, steady activity and b) unstable behavior several times per day. The spattering represents outgassing of shallowly accumulated gas in the lake. Therefore, although steady lava lake behavior at Halema`uma`u may be deeply driven by upwelling of magma, we argue that the sporadic interruptions to this behavior are the result of shallow processes occurring near the lake surface. These observations provide a cautionary note that some lava lake behavior is not representative of deep-seated processes. This behavior also highlights the complex and dynamic nature of lava lake activity.

  14. Interpreting Low Spatial Resolution Thermal Data from Active Volcanoes on Io and the Earth

    NASA Technical Reports Server (NTRS)

    Keszthelyi, L.; Harris, A. J. L.; Flynn, L.; Davies, A. G.; McEwen, A.

    2001-01-01

    The style of volcanism was successfully determined at a number of active volcanoes on Io and the Earth using the same techniques to interpret thermal remote sensing data. Additional information is contained in the original extended abstract.

  15. Temporal and spectral characteristics of seismicity observed at Popocatepetl volcano, central Mexico

    USGS Publications Warehouse

    Arciniega-Ceballos, A.; Valdes-Gonzalez, C.; Dawson, P.

    2000-01-01

    Popocatepetl volcano entered an eruptive phase from December 21, 1994 to March 30, 1995, which was characterized by ash and fumarolic emissions. During this eruptive episode, the observed seismicity consisted of volcano-tectonic (VT) events, long-period (LP) events and sustained tremor. Before the initial eruption on December 21, VT seismicity exhibited no increase in number until a swarm of VT earthquakes was observed at 01:31 hours local time. Visual observations of the eruption occurred at dawn the next morning. LP activity increased from an average of 7 events a day in October 1994 to 22 events per day in December 1994. At the onset of the eruption, LP activity peaked at 49 events per day. LP activity declined until mid-January 1995 when no events were observed. Tremor was first observed about one day after the initial eruption and averaged 10 h per episode. By late February 1995, tremor episodes became more intermittent, lasting less than 5 min, and the number of LP events returned to pre-eruption levels (7 events per day). Using a spectral ratio technique, low-frequency oceanic microseismic noise with a predominant peak around 7 s was removed from the broadband seismic signal of tremor and LP events. Stacks of corrected tremor episodes and LP events show that both tremor and LP events contain similar frequency features with major peaks around 1.4 Hz. Frequency analyses of LP events and tremor suggest a shallow extended source with similar radiation pattern characteristics. The distribution of VT events (between 2.5 and 10 km) also points to a shallow source of the tremor and LP events located in the first 2500 m beneath the crater. Under the assumption that the frequency characteristics of the signals are representative of an oscillator we used a fluid-filled-crack model to infer the length of the resonator.

  16. Research on identification of active volcano features based on Landsat TM/ETM+ imagery

    NASA Astrophysics Data System (ADS)

    Kong, Xiangsheng; Qian, Yonggang

    2009-10-01

    Volcanic activity can present unpredictable disasters to city populations living within regions and for people traveling in plane that intersect with ash-laden eruption clouds. Methods of monitoring volcanic activity include searching for variations in the thermal anomaly, clouds resource and subsidence deformation from active volcano. Over any active volcanoes, low spatial resolution satellite image are used to identify changes in eruptive activity, but are of insufficient spatial resolution to map active volcanic features. The Landsat data can be used to identify the thermal characteristics of a series of lava flows at Fuego volcano and Pacaya volcano, Guatemala. We use Landsat TM/ETM+ 7, 5, 4 (displayed in red, green, and blue, respectively) false-color composite of the research region, acquired on 18 December 1989 and 23 January 2000 to indicate the volcano image features which appear halo structure with blue red and yellow. The interpretation flag is obvious which indicate the difference temperature of volcano crater. Spatially varying haze emitted by volcano activity is identified and removed based on Improved Haze Optimized Transform (HOT) which is a robust haze assessing method. With improved spatial resolution in the thermal IR, we are able to map the bifurcation and braiding of underground lava tubes. With higher spatial resolution panchromatic data, we are able to map lava flow fields, trace very high temperature lava channels, and identify an accurate feature associated with a collapsed crater floor. At both Fuego and Pacaya, we are able to use the thermal data to estimate temperature. We can monitor the dynamic change of the two volcanoes using two difference date Landsat data.

  17. Infrasound of basaltic effusive activity at Piton de la Fournaise Volcano

    NASA Astrophysics Data System (ADS)

    Genco, Riccardo; Valade, Sebastien; Villeneuve, Nicolas; Peltier, Aline; Ferrazzini, Valérie; Di Muro, Andrea; Ripepe, Maurizio

    2016-04-01

    On August 24th 2015, a 67 days long eruptive activity started at Piton de la Fournaise Volcano. During the last phases of the eruption we deployed a portable, small aperture, infrasonic array which allowed us to record unprecedented data from effusive volcanic activity. The array consisted on four, few tens of meters spaced, infrasound pressure sensors and was installed on the outer rim of the Enclos Foqué, roughly 2.5 km far from the active vent, sited on the southern flank of the central cone. The system was almost continuously operating from October, 15th to December, 7th 2015, thus recording the end of the first eruptive phase (Autust 24th - October 17th) as well as the two short-living following phases (from 22 to 24 and from 29 to 31 October, 2015). The infrasound records have been coupled with discrete high-rate (30 Hz) thermal and visible imagery acquisitions located at a short distance from the vent (100-200 m) providing detailed information on the eruptive source dynamics. The comparison with seismic and ground tilt data recorded by the permanent network operated by the Observatoire Volcanologique du Piton de la Fournaise (OVPF), shows that infrasound can be succesfully used to locate the source, detect the onset, and the end, of the effusive phases as well as accurately track the time evolution of the effusive process. We present results which allows a detailed analysis of the shallow magma dynamics during the effusive activity at Piton de la Fournaise Volcano. As far as we know these are amongst the few rare infrasound dataset reported for this style of basaltic volcanic activity.

  18. Digital Data for Volcano Hazards at Newberry Volcano, Oregon

    USGS Publications Warehouse

    Schilling, S.P.; Doelger, S.; Sherrod, D.R.; Mastin, L.G.; Scott, W.E.

    2008-01-01

    Newberry volcano is a broad shield volcano located in central Oregon, the product of thousands of eruptions, beginning about 600,000 years ago. At least 25 vents on the flanks and summit have been active during the past 10,000 years. The most recent eruption 1,300 years ago produced the Big Obsidian Flow. Thus, the volcano's long history and recent activity indicate that Newberry will erupt in the future. Newberry Crater, a volcanic depression or caldera has been the focus of Newberry's volcanic activity for at least the past 10,000 years. Newberry National Volcanic Monument, which is managed by the U.S. Forest Service, includes the caldera and extends to the Deschutes River. Newberry volcano is quiet. Local earthquake activity (seismicity) has been trifling throughout historic time. Subterranean heat is still present, as indicated by hot springs in the caldera and high temperatures encountered during exploratory drilling for geothermal energy. The report USGS Open-File Report 97-513 (Sherrod and others, 1997) describes the kinds of hazardous geologic events that might occur in the future at Newberry volcano. A hazard-zonation map is included to show the areas that will most likely be affected by renewed eruptions. When Newberry volcano becomes restless, the eruptive scenarios described herein can inform planners, emergency response personnel, and citizens about the kinds and sizes of events to expect. The geographic information system (GIS) volcano hazard data layers used to produce the Newberry volcano hazard map in USGS Open-File Report 97-513 are included in this data set. Scientists at the USGS Cascades Volcano Observatory created a GIS data layer to depict zones subject to the effects of an explosive pyroclastic eruption (tephra fallout, pyroclastic flows, and ballistics), lava flows, volcanic gasses, and lahars/floods in Paulina Creek. A separate GIS data layer depicts drill holes on the flanks of Newberry Volcano that were used to estimate the probability

  19. Toward a general view of mantle peridotite beneath the volcanic front: petrology of peridotite xenoliths from Bezymyanny volcano (central Kamchatka)

    NASA Astrophysics Data System (ADS)

    Ishimaru, S.; Arai, S.; Tamura, A.; Okrugin, V. M.; Shcherbakov, V.; Plechov, P.

    2012-04-01

    We have a large amount of data about petrological and geochemical features of upper mantle peridotites based on researches of mantle xenoliths, ophiolites or solid intrusions. But the nature of sub-arc mantle, especially beneath a volcanic front, has not been fully understood due to the scarcity of occurrences of mantle-derived materials there. Kamchatka Peninsula is one of the active volcanic arcs, having 29 active volcanoes, and 13 volcanoes of them contain cognate or mantle peridotite xenoliths (Erlich et al., 1979). Peridotite xenoliths derived from the upper mantle beneath the volcanic front are expected from 9 of them (Erlich et al., 1979). Avachinsky (Avacha) volcano is the most famous of them because of its easy accessibility and high xenolith production. Peridotite xenoliths from Avacha record high degree of melting and multiple stages of metasomatism (e.g., Ishimaru et al., 2007; Ionov, 2010). Formation of secondary orthopyroxenes replacing olivine is one of characteristics of arc-derived peridotite xenoliths (e.g., Arai & Kida, 2000; McInnes et al., 2001). In addition, we found peculiar metasomatisms, e.g., Ni enrichment (e.g., Ishimaru and Arai, 2008), in the Avacha peridotite xenolith suite. Here, we show petrological and geochemical features of ultramafic xenoliths from Bezymyanny volcano, central Kamchatka, to obtain a more generalized view of the sub-front mantle. We examined 2 harzburgite xenoliths from Bezymyanny. They are composed of fine-grained minerals (cf. Arai and Kida, 2000), and occasionally contain hornblende and/or phlogopite. Almost all orthopyroxenes show irregular shapes and replace olivine, indicating a secondary origin. At the boundary between the harzburgite and host andesite, we observed hornblende and secondary orthopyroxenes. At the xenoliths' interior, Fo content of olivine and Cr# (= Cr/(Cr + Al) atomic ratio) of chromian spinel are high, 91-92 and 0.43-0.69, respectively, and the Fo content decreases to 76 at the boundary

  20. Reawakening of a volcano: Activity beneath Eyjafjallajökull volcano from 1991 to 2009

    NASA Astrophysics Data System (ADS)

    Hjaltadóttir, Sigurlaug; Vogfjörd, Kristín S.; Hreinsdóttir, Sigrún; Slunga, Ragnar

    2015-10-01

    The ice-capped Eyjafjallajökull volcano, south Iceland, had been dormant for 170 years when the first signs of reawakening of the volcano were captured by seismic and geodetic measurements in 1994. These were the first clear observed signs of unrest followed by 16 years of intermittent magmatic unrest culminating in 2010 when two eruptions broke out on the flank and at the summit. We analyze seismic data from 1991 through 2008 and GPS data from 1992 to May 2009 to infer magma movements beneath the volcano. The relocated earthquakes reveal an overall pipe-like pattern northeast of the summit crater, sporadically mapping the pathway of magma from the base of the crust towards an intrusion in the upper crust. During the study period, three major seismic swarms were recorded. Two of them, in 1994 and 1999-2000, occurred in the upper and intermediate crust and accompanied crustal deformation centered at the southeastern flank. No uplift was detected during the 19- to 25-km-deep 1996 swarm, near the crust-mantle boundary, but the horizontal, ~ E-W oriented T-axes indicate a period of tension/opening, suggesting magma intruding up into the base of the crust. The GPS measured deformation during 1999-2000 can be modeled as intrusion of a horizontal, circular sill with volume of 0.030 ± 0.007 km3 at 5.0 ± 1.3 km depth. The less constrained 4.5- to 5-km-deep sill model for the 1994 episode indicates a three times smaller intruded volume (0.011 km3) than during 1999-2000. In the years between/following the intrusions, contraction was observed at the southeastern flank. The contraction from 2000.5 to 2009.3 can be fitted by a circular sill model with a volume contraction of - 0.0015 ± 0.0003 km3/year at 5.5 ± 2.0 km depth. The less well constrained model for 1994.7 to 1998.6 gives a volume contraction of -(0.0009-0.0010) km3 at a fixed depth of 5 km. The accumulated volume changes (~- 0.013 km3 for the second period, ~ 0.0037 km3 for the first period) are much larger than

  1. Blast waves from violent explosive activity at Yasur volcano, Vanuatu

    NASA Astrophysics Data System (ADS)

    Marchetti, E.; Ripepe, M.; Delle Donne, D.; Genco, R.; Finizola, A.; Garaebiti, E.

    2013-12-01

    The violent Strombolian activity at Yasur volcano (Vanuatu) was recorded with infrasonic, seismic and thermal sensors. Infrasound array allowed to identify and stack ~3000 infrasonic and seismic transiensts of explosions from two distinct vents. The stacked seismic signals evidence a low-frequency (0.15 Hz) signal preceding of ~5-6 s the explosion that was hidden by the high seismic tremor and microseism. Infrasonic signals are self-similar presenting a stable strong asymmetry, with a sharp positive pressure (5-106 Pa) onset followed by a longer lasting negative rarefaction phase. Self-similarity and asymmetry of the recorded pressure waveforms are recalling blast waves. Regardless the pressure amplitude, ratio between the positive and negative phase is constant. This fit the Friedland waveform and support the blast wave model. Thermal imagery detects this pressure wave as soon as it exits the vent as a relative ~20 m thick cold front, which radiates spherically from the source. This front of apparent cold temperature is moving before the volcanic hot gas/fragments cloud at a velocity ranging between 342 and 403 m/s. We interpret this cold front as produced by the change of the atmospheric refraction index induced by the passage of the shock front. Assuming a supersonic dynamics, we calculate that the mean acoustic pressure (25 Pa) recorded at the array is generated by a a gas expansion velocity of 372 m/s equivalent to Mach number of 1.1. Our data are then suggesting that explosive activity at Yasur is able to generate blast waves indicating supersonic gas expansion. Blast waves are expected and well documented for Plinian and Vulcanian eruptions, but have never been recorded during Strombolian events. This evidence has a direct consequence on the source modeling of infrasonic transients explosions as it requires non-linear source dynamics to explain also small scale (VEI<2) explosive processes.

  2. Diffuse Emission of Carbon Dioxide From Irazú Volcano, Costa Rica, Central America

    NASA Astrophysics Data System (ADS)

    Galindo, I.; Melian, G.; Ramirez, C.; Salazar, J.; Hernandez, P.; Perez, N.; Fernandez, M.; Notsu, K.

    2001-12-01

    Irazú (3,432 m) is a stratovolcano situated 50 Km east of San José, the capital of Costa Rica. Major geomorphological features at Irazú are five craters (Main Crater, Diego de La Haya, Playa Hermosa, La Laguna and El Piroclástico), and at least 10 satellitic cones which are located on its southern flank. Its eruptive history is known from 1723. Since then, have ocurred at least 23 eruptions. All known Holocene eruptions have been explosive. The focus of eruptions at the summit crater complex has migrated to the west towards the historically active crater from 1963 to 1965. Diffuse degassing studies are becoming an additional geochemical tool for volcanic surveillance. The purpose of this study is to evaluate the spatial distribution of diffuse CO2 emission as well as CO2 efflux from Irazú volcano. A soil CO2 flux survey of 201 sampling sites was carried out at the summit of Irazú volcano in March 2001. Sampling site distribution covered an area of 3.5 Km2. Soil CO2 efflux measurements were performed by means of a portable NDIR sensor LICOR-800. Soil CO2 efflux values ranged from non-detectable values to 316.1 gm-2d-1 Statistical-graphical analysis of the data showed three overlapping geochemical populations. The background mean is 3 gm-2d-1 and represents 91.3 % of the total data. Peak group showed a mean of 18 gm-2d-1 and represented 1.2 % of the data. Anomalous CO2 flux values are mainly detected in the South sector of the main crater, where landslides have previously occurred. Diffuse CO2 degassing rate of the study area yields 44.2 td-1.

  3. Geomorphic assessment of the debris avalanche deposit from the Jocotitlán volcano, Central Mexico

    NASA Astrophysics Data System (ADS)

    Salinas, Sergio; López-Blanco, Jorge

    2010-11-01

    Edifice collapse of the Jocotitlán volcano produced a debris avalanche deposit whose morphology is characterized by conical hummocks and elongated ridges. We consulted aerial photographs, orthophotographs, and conducted field work to define field relationships between mound morphology and stratigraphy. Based on field evidence and geomorphic and geologic interpretation we sub-divide the deposit into three sectors (north, northeastern, and eastern). We determine the emplacement mechanisms of the different sectors based on their distinct morphologic and lithologic features. In this context, we generate a geomorphometric database comprising 17 variables for each mound and apply multivariate statistical methods (principal component analysis and cluster analysis) to define the relationships between them. The principal components incorporated 73% of the total data variance and seven geomorphometric variables (perimeter, major axis, area, height, distance to the source, axis ratio and circularity index) defined two groups: hummocks and ridges. The circularity index and the axis ratio best characterize the elongated form of hummocks composing the deposits. Contrasts in lithological characteristics, such as material strength and mobility, provide evidence for a transition from a sliding mass (debris avalanche deposit) to a debris-flow-like emplacement. Differences in deposit morphology suggest two collapse mechanisms: magmatic intrusion (Bezymianny-type sector collapse) and a tectonic mass-slide, an earthquake could provide the trigger for both collapses. The eastern lower flank of the volcano then collapsed gravitationally due to a movement along a fault (tectonic activity possibly related to the Acambay-Tixmadeje Fault System). This produced the northeastern sector of the debris avalanche deposit dominated by large elongated ridges. The spatial arrangement of both sectors (the N and NE) suggests that the two failure events occurred simultaneously. Finally, the eastern

  4. Genesis of adakite-like lavas of Licancabur volcano (Chile—Bolivia, Central Andes)

    NASA Astrophysics Data System (ADS)

    Figueroa, Oscar; Déruelle, Bernard; Demaiffe, Daniel

    2009-04-01

    The Licancabur volcano is located on the Bolivia—Chile Altiplano (Central Andes). The lavas are andesites and dacites. Numerous mineralogic features attest that magma mixing occurred. Andesites have concave (spoon-shaped) REE patterns whereas dacites have steep slopes. A spectacular crossover of patterns occurs with increasing SiO 2. Most geochemical discrimination criteria of adakites are satisfied by Licancabur dacites, except their high Sr-isotope compositions (> 0.7075). For the genesis of the Licancabur adakite-like lavas, a four-step model is proposed: (1) partial melting (5 to 10 wt %) of a subducted altered oceanic crust; (2) hybridation (< 10 wt %) of the magmas with melts derived from the overlying lithospheric mantle; (3) contamination (≈ 1 wt %) of these hybrid magmas by TTG-type granodiorites of the Archean lower continental crust (with present-day Sr-isotope ratios ≈ 0.820); (4) evolution and differentiation by crystal fractionation (< 6 wt %) and magma mixing at upper crustal levels.

  5. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Near, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of the Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analysed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analysed using data from the European Remote Sensing Satellites (ERS), the Japanese Earth Resources Satellite (JERS) and the US Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  6. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Neal, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analyzed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analyzed using data from the European Remote Sensing Satellites (ERS), Japanese Earth Resources Satellite (JERS) and the U. S. Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  7. Subglacial melting associated with activity at Bárdarbunga volcano, Iceland, explored using numerical reservoir simulations

    NASA Astrophysics Data System (ADS)

    Reynolds, Hannah I.; Gudmundsson, Magnús T.; Högnadóttir, Thórdís

    2015-04-01

    Increased seismic activity was observed within the caldera of Bárdarbunga, a central volcano beneath Vatnajökull glacier, on 16 August 2014. The seismicity traced the path of a lateral dyke, initially propagating to the south east of the volcano, before changing course and continuing beyond the northern extent of the glacier. A short fissure eruption occurred at the site of the Holuhraun lavas on 29 August, lasting for approximately 5 hours and producing less than 1 million cubic meters of lava, before recommencing in earnest on 31 August with the large effusive eruption, which is still ongoing at the time of writing. The glacier surface has been monitored aerially since the onset of heightened seismic activity, and the caldera and dyke propagation path surveyed using radar profiling. Ice cauldrons are shallow depressions which form on the glacier surface due to basal melting, as a manifestation of heat flux from below; the melting ice acts as a calorimeter, allowing estimations of heat flux magnitude to be made. Several cauldrons were observed outside the caldera, two to the south east of Bárdarbunga, and three located above the path of the dyke under the Dyngjujökull outlet glacier. The cauldrons range in volume from approximately 0.001 km3 to 0.02 km3. We present time series data of the development and evolution of these cauldrons, with estimates of the heat flux magnitudes involved. The nature of the heat source required to generate the aforementioned cauldrons is not obvious and two scenarios are explored: 1) small subglacial eruptions; or 2) increased geothermal activity induced by the dyke intrusion. We investigate these scenarios using analytical and finite element modelling, considering the surface heat flux produced, and timescales and spatial extent of associated surface anomalies. A range of permeabilities has been explored. It is found that an intrusion of a dyke or sill into rocks where the groundwater is near or at the boiling point curve can

  8. Recent Eruptive Activity at Etna Volcano Inferred by Borehole Strainmeters : Source Modeling and Magma Volume Balance

    NASA Astrophysics Data System (ADS)

    Bonaccorso, Alessandro; Calvari, Sonia; Currenti, Gilda; Linde, Alan; Sacks, Selwyn

    2015-04-01

    After the end of the last effusive flank 2008-2009 eruption, in January 2011 the eruptive activity resumed at Etna producing a new phase with 44 lava fountain episodes through December 2013. Almost all the lava fountains had similar characteristics. The intensity of the initial strombolian explosions increased rapidly and the activity soon shifted to lava fountains. The paroxysmal phase was accompanied by increasing tephra emission with lava fountain reaching up to ~0.5-0.8 km above the crater and an eruption column rising several kilometers above the volcano summit before being dispersed by wind to the distal volcano flanks and by lava flow output. The paroxysmal episodes lasted a few hours and fed lava flows that expanded in the Valle del Bove depression with maximum lengths of 4-6 km. These eruptive episodes emitted much more magma than in the phases occurred in the previous decades. In November 2011, the first two borehole strainmeters, dilatometers type with nominal precision of ~ 10^10 - 10^11, were installed at Etna at ~180 m depth below the ground surface with distances from the summit central crater of 6 (DEGI) and 10 km (DRUV), respectively. During the paroxysmal events these high precision instruments detected negative strain changes indicating medium expansion at both sites. For each fountain episode the amplitude of the stain changes were almost similar with ~0.2 and ~1 μstrain at DRUV and DEGI, respectively. A Finite Element Model was set up to estimate accurately the tilt and volumetric strain, taking into account the real profile of the volcano and the elastic medium heterogeneity. The numerical computations indicated an elongated depressurizing source located at 0 km b.s.l., which underwent a volume change of ~2 × 106 m3 which is the most of the magma volume erupted, while a smaller remaining part (~0.5 × 106 m^3) is accommodated by the magma compressibility. This allowed to infer a representative average erupted volume of ~2.5 × 106 m3 for

  9. Seismic Study of the Velocity Structure and Earthquake FocalMechanisms beneath the Krafla Central Volcano, NE Iceland

    NASA Astrophysics Data System (ADS)

    Martens, H. R.; Schuler, J.; Greenfield, T. S.; White, R. S.; Roecker, S. W.; Brandsdottir, B.; Stock, J. M.; Tarasewicz, J.; Pugh, D. J.

    2015-12-01

    We investigated the seismic velocity structure of the Krafla central volcano, NE Iceland, and its shallow geothermal fields. In our 3D tomographic inversions, we used passive seismic data recorded between 2009-2012 from a temporary local network as well as active seismic legacy data to constrain the velocity models. We find high P-wave velocities (Vp) underneath regions of elevated topographic relief as well as two low-Vp anomalies that coincide spatially with two attenuating bodies outlined from S-wave shadows during the Krafla rifting episode of 1974-1985. Within the Krafla geothermal reservoir, which is developed for energy production, we imaged a shallow low-Vp/Vs zone overlying a deeper high-Vp/Vs zone and interpreted them as steam- and brine-bearing formations, respectively. Previously undertaken borehole measurements support our findings. A prominent low-Vp/Vs anomaly underlies these zones at rock depths greater than 1.5 km, where a super-heated zone within felsic overlies rhyolitic within the geothermal melt. Calculations systems show that of the most earthquake focal events are mechanisms consistent double-couple source models with only a few clear non-shear source models.

  10. Synchronous degassing patterns of the neighbouring volcanoes Llaima and Villarrica in south-central Chile: the influence of tidal forces

    NASA Astrophysics Data System (ADS)

    Bredemeyer, Stefan; Hansteen, Thor H.

    2014-10-01

    The neighbouring volcanoes Villarrica and Llaima are two of the most active volcanoes in Chile and both currently degas continuously. We present a semi-continuous time series of SO2 fluxes for Villarrica and Llaima volcanoes. The time series was obtained using five scanning Mini-Differential Optical Absorption Spectrometers (Mini-DOAS, UV spectrometers) over 6 months (13 February to 31 July 2010) and is based on 6,829 scans for Villarrica and 7,165 scans for Llaima. Statistical analyses of the SO2 flux time series reveal a periodicity of degassing maxima about every 7 days, and further a conspicuous synchronicity of the degassing maxima and minima between the two volcanoes. Intra-day variations in SO2 fluxes also show a striking correlation between Villarrica and Llaima. All these patterns correlate well with the trend of the modelled solid Earth tide curves, where the 7-day degassing maxima correspond with both the fortnightly tidal maxima and minima. The intra-day degassing peaks mostly correlate well with the periods of maximum deformation rates during the diurnal tidal cycle, and further with semidiurnal minima in atmospheric pressure, a phenomenon we refer to as "the tidal pump". As there is little time lag between the tidal action and the changes in degassing rates, we infer that degassing at both volcanoes is controlled by conduit convection, involving physical separation between gas and magma at comparatively shallow levels. Variations in daily degassing rates were up to a factor of ca. 12 and 10 for Villarrica and Llaima, respectively, without any noticeable changes in the periodicity. We thus suggest that the described cyclic variations must be taken into account for all comparable volcanoes when using gas monitoring as a tool for volcanic hazard mitigation.

  11. Magmas with slab fluid and decompression melting signatures coexisting in the Gulf of Fonseca: Evidence from Isla El Tigre volcano (Honduras, Central America)

    NASA Astrophysics Data System (ADS)

    Mattioli, Michele; Renzulli, Alberto; Agostini, Samuele; Lucidi, Roberto

    2016-01-01

    Isla El Tigre volcano is located in the Gulf of Fonseca (Honduras) along the Central America volcanic front, where a significant change in the strike of the volcanic chain is observed. The studied samples of this poorly investigated volcano are mainly subalkaline basic to intermediate lavas (basalts and basaltic andesites) and subordinate subalkaline/alkaline transitional basalts, both having the typical mineralogical and geochemical characteristics of arc volcanic rocks. On the basis of petrographic and geochemical features, two groups of rocks have been distinguished. Lavas from the main volcanic edifice are highly porphyritic and hy-qz normative, and have lower MgO contents (< 5 wt.%). They show significant LILE and LREE enrichments and Nb-Ta depletions, and have a strong slab signature as well as incompatible element contents similar to those of the main front of the adjacent volcanoes in El Salvador and Nicaragua (e.g., Ba/La up to 80). In contrast, lavas from the parasitic cones have higher MgO contents (> 5 wt.%), are ol-hy normative and show lower HFSE depletions relative to LILE and LREE, with lower Ba/La, Ba/Nb and Zr/Nb ratios. This suggests that mantle-derived magmas were not produced by the same process throughout the activity of the volcano. The bulk rock geochemistry and 87Sr/86Sr (0.70373-0.70382), 143Nd/144Nd (0.51298-0.51301), 206Pb/204Pb (18.55-18.58), 207Pb/204Pb (15.54-15.56) and 208Pb/204Pb (38.23-38.26) isotopic data of Isla El Tigre compared with the other volcanoes of the Gulf of Fonseca and all available literature data for Central America suggests that this stratovolcano was mainly built by mantle-derived melts driven by slab-derived fluid-flux melting, while magmas erupted through its parasitic cones have a clear signature of decompression melting with minor slab contribution. The coexistence of these two different mantle melting generation processes is likely related to the complex geodynamic setting of the Gulf of Fonseca, where the

  12. Merapi Volcano, Central Java, Indonesia: A case study of radionuclide behavior in volcanic gases and its implications for magma dynamics at andesitic volcanoes

    NASA Astrophysics Data System (ADS)

    Le Cloarec, Marie-FrançOise; Gauthier, Pierre-J.

    2003-05-01

    For more than 20 years, volcanic gases have been regularly collected at Merapi Volcano, Indonesia, and have been subsequently analyzed for their (210Pb), (210Bi), and (210Po) activities and SO2 contents. These new results show the high volatility of the three radionuclides in andesitic gases, although their emanation coefficients (0.94%, 3.5%, and ≤53% for 210Pb, 210Bi, and 210Po, respectively) are significantly lower than those observed at basaltic volcanoes. This emphasizes the major role of magma temperature on the degassing of these metals, which are mainly transported in volcanic gases as Pb-chloride compounds and as Bi- and Po-metallic species. Radioactive disequilibria between 210Pb, 210Bi, and 210Po in the gas phase are characteristic of degassing processes and gas paths within the edifice. Gases released at both Gendol and Woro fumarolic fields are of magmatic origin, but their radionuclide content is strongly altered by secondary processes (chemical reactions with surrounding brines and deposition of sublimates in the ground). High-temperature gases collected in the summit gas plume are of pure primary magmatic origin and are likely directly tapped in the degassing reservoir. Gases arising from the growing domes are strongly depleted in the most volatile isotopes and gas species. This suggests that magma mostly degasses at depth in open system, explaining why the volcano usually undergoes no explosive eruptions. The gas flux at Merapi is sustained by a deep magma supply which is twice the extrusion rate of lava. Unerupted degassed magma thus progressively accumulates beneath the summit, yielding an overpressure which can trigger dome collapse without precursor.

  13. Giant magmatic water reservoir beneath Uturuncu volcano and Altiplano-Puna region (Central Andes)

    NASA Astrophysics Data System (ADS)

    Laumonier, Mickael; Gaillard, Fabrice; Muir, Duncan; Blundy, Jon; Unsworth, Martyn

    2016-04-01

    Volcanism at continental arcs is the surface manifestation of long-lived crustal magmatic processes whereby mantle-derived hydrous basalt magma differentiates to more silica-rich magmas by a combination of crystallization and crustal melting. What erupts is just a fraction of the total volume of magma produced by these processes; the unerupted, plutonic residues solidify and are inaccessible to direct study until millions of years of uplift and erosion bring them to the surface. In contrast, geophysical surveys, using electromagnetic and seismic waves, can provide real-time images of subduction zone magmatic systems. Several such studies have revealed that arc volcanoes are underlain by large partially molten regions at depths of >10 km, the largest known example being the Altiplano-Puna magma body (APMB) in central Andes. Interpreting such geophysical images in terms of amount, composition and distribution of partial melts is limited by our lack of knowledge of the physical properties of silicate melts at elevated pressures and temperatures. Here we present high-pressure, in situ experimental data showing that the electrical conductivity of andesitic melts is primarily controlled by their dissolved water contents. Linking our new measurements to petrological constraints from andesites erupted on the Altiplano, we show that the APMB is composed of 10-20% of an andesitic melt containing 8-10 wt% dissolved water. This implies that the APMB is a giant water anomaly in the global subduction system, with a total mass of dissolved magmatic water about half of the water contained within the Adriatic Sea. In addition to the controls on the physical properties of the melts, the abundance of dissolved water governs the structural levels of magma ponding, equivalent to the depth of water saturation, where degassing and crystallisation promote partial melting and weakening of the upper crust. Unexpectedly, very high concentrations of water in andesite magmas shall impede their

  14. 2010 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2014-01-01

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

  15. Volcanic history of El Chichon Volcano (Chiapas, Mexico) during the Holocene, and its impact on human activity

    USGS Publications Warehouse

    Espindola, J.M.; Macias, J.L.; Tilling, R.I.; Sheridan, M.F.

    2000-01-01

    Before its devastating eruption in 1982, El Chichon Volcano was little known and did not appear on any listings of hazardous volcanoes. Subsequent geologic studies, based on stratigraphic and radiocarbon investigations, showed that at least three explosive eruptions had occurred previously at this volcano. In this paper, we present the result of recent studies on the stratigraphy of the volcano and new radiocarbon ages which show that at least 11 eruptions have taken place at El Chichon in the past 8000 years. Explosive events, most of them producing block-and-ash flow and surge deposits, occurred around 550, 900, 1250, 1500, 1600, 1900, 2000, 2500, 3100, 3700 and 7700 years BP. The juvenile products of these eruptions have a trachyandesitic composition with similar degree of evolution, as evidenced from their SiO2 abundance and depletion in MgO, CaO, TiO2, as well as trace and rare earth elements. This suggests segregation of olivine and orthopyroxene from the melt. Since human settlements in southeast Mexico and Central America can be traced as far back as approximately 2500 years BP, most of these events probably affected human activity. In fact, there are reports of pottery shards and other artifacts in deposits from the eruption of 1250 BP. Pottery fragments in deposits of an eruption that took place 2500 BP are also reported in this paper. Thus, the impact of the volcano on human activities has been frequent, with most of the repose intervals lasting between 100 to 600 years. The impact of the eruptions was probably of greater than local extent, because airfall tephra could reach distant sites and possibly even affect weather. The eruptive history of El Chichon also offers clues in the investigation of the Maya civilization. Several researchers have considered the volcano as an important factor in the answer to some intriguing questions such as the extensive use of volcanic ash in Late Classic Maya ceramics or, of greater importance, the causes of the

  16. Volcanic history of El Chichón Volcano (Chiapas, Mexico) during the Holocene, and its impact on human activity

    NASA Astrophysics Data System (ADS)

    Espíndola, J. M.; Macías, J. L.; Tilling, R. I.; Sheridan, M. F.

    Before its devastating eruption in 1982, El Chichón Volcano was little known and did not appear on any listings of hazardous volcanoes. Subsequent geologic studies, based on stratigraphic and radiocarbon investigations, showed that at least three explosive eruptions had occurred previously at this volcano. In this paper, we present the result of recent studies on the stratigraphy of the volcano and new radiocarbon ages which show that at least 11 eruptions have taken place at El Chichón in the past 8000years. Explosive events, most of them producing block-and-ash flow and surge deposits, occurred around 550, 900, 1250, 1500, 1600, 1900, 2000, 2500, 3100, 3700 and 7700years BP. The juvenile products of these eruptions have a trachyandesitic composition with similar degree of evolution, as evidenced from their SiO2 abundance and depletion in MgO, CaO, TiO2, as well as trace and rare earth elements. This suggests segregation of olivine and orthopyroxene from the melt. Since human settlements in southeast Mexico and Central America can be traced as far back as approximately 2500years BP, most of these events probably affected human activity. In fact, there are reports of pottery shards and other artifacts in deposits from the eruption of 1250 BP. Pottery fragments in deposits of an eruption that took place 2500 BP are also reported in this paper. Thus, the impact of the volcano on human activities has been frequent, with most of the repose intervals lasting between 100 to 600years. The impact of the eruptions was probably of greater than local extent, because airfall tephra could reach distant sites and possibly even affect weather. The eruptive history of El Chichón also offers clues in the investigation of the Maya civilization. Several researchers have considered the volcano as an important factor in the answer to some intriguing questions such as the extensive use of volcanic ash in Late Classic Maya ceramics or, of greater importance, the causes of the collapse

  17. Observed inflation-deflation cycles at Popocatepetl volcano using tiltmeters and its possible correlation with regional seismic activity in Mexico

    NASA Astrophysics Data System (ADS)

    Contreras Ruiz Esparza, M. G., Sr.; Jimenez Velazquez, J. C., Sr.; Valdes Gonzalez, C. M., Sr.; Reyes Pimentel, T. A.; Galaviz Alonso, S. A.

    2014-12-01

    Popocatepetl, the smoking mountain, is a stratovolcano located in central Mexico with an elevation of 5450 masl. The active volcano, close to some of the largest urban centers in Mexico - 60 km and 30 km far from Mexico City and Puebla, respectively - poses a high hazard to an estimated population of 500 thousand people living in the vicinity of the edifice. Accordingly, in July 1994 the Popocatepetl Volcanological Observatory (POVO) was established. The observatory is operated and supported by the National Center for Disaster Prevention of Mexico (CENAPRED), and is equipped to fully monitor different aspects of the volcanic activity. Among the instruments deployed, we use in this investigation two tiltmometers and broad-band seismometers at two sites (Chipiquixtle and Encinos), which send the information gathered continuously to Mexico City.In this research, we study the characteristics of the tiltmeters signals minutes after the occurrence of certain earthquakes. The Popocatepetl volcano starts inflation-deflation cycles due to the ground motion generated by events located at certain regions. We present the analysis of the tiltmeters and seismic signals of all the earthquakes (Mw>5) occurred from January 2013 to June 2014, recorded at Chipiquixtle and Encinos stations. First, we measured the maximum tilt variation after each earthquake. Next, we apply a band-pass filter for different frequency ranges to the seismic signals of the two seismic stations, and estimated the total energy of the strong motion phase of the seismic record. Finally, we compared both measurements and observed that the maximum tilt variations were occurring when the maximum total energy of the seismic signals were in a specific frequency range. We also observed that the earthquake records that have the maximum total energy in that frequency range were the ones with a epicentral location south-east of the volcano. We conclude that our observations can be used set the ground for an early

  18. Volcano seismicity in Alaska

    NASA Astrophysics Data System (ADS)

    Buurman, Helena

    I examine the many facets of volcano seismicity in Alaska: from the short-lived eruption seismicity that is limited to only the few weeks during which a volcano is active, to the seismicity that occurs in the months following an eruption, and finally to the long-term volcano seismicity that occurs in the years in which volcanoes are dormant. I use the rich seismic dataset that was recorded during the 2009 eruption of Redoubt Volcano to examine eruptive volcano seismicity. I show that the progression of magma through the conduit system at Redoubt could be readily tracked by the seismicity. Many of my interpretations benefited greatly from the numerous other datasets collected during the eruption. Rarely was there volcanic activity that did not manifest itself in some way seismically, however, resulting in a remarkably complete chronology within the seismic record of the 2009 eruption. I also use the Redoubt seismic dataset to study post-eruptive seismicity. During the year following the eruption there were a number of unexplained bursts of shallow seismicity that did not culminate in eruptive activity despite closely mirroring seismic signals that had preceded explosions less than a year prior. I show that these episodes of shallow seismicity were in fact related to volcanic processes much deeper in the volcanic edifice by demonstrating that earthquakes that were related to magmatic activity during the eruption were also present during the renewed shallow unrest. These results show that magmatic processes can continue for many months after eruptions end, suggesting that volcanoes can stay active for much longer than previously thought. In the final chapter I characterize volcanic earthquakes on a much broader scale by analyzing a decade of continuous seismic data across 46 volcanoes in the Aleutian arc to search for regional-scale trends in volcano seismicity. I find that volcanic earthquakes below 20 km depth are much more common in the central region of the arc

  19. Late Pleistocene/Holocene paleoclimate reconstruction and eruptive history of Central American volcanoes from lake bottom sediments of Lake Nicaragua

    NASA Astrophysics Data System (ADS)

    Wulf, S.; Dull, R. A.; Mann, P.; McIntosh, K. D.; Gardner, J. E.

    2007-12-01

    A shallow coring program in Lake Nicaragua was completed in May/June 2006 by the University of Texas (UT Department of Geography and UT Institute for Geophysics). A total of 35 sediment cores with lengths ranging between 12 cm and 100 cm along with five longer cores were extracted from the lake using a gravity corer and a modified manual square rod piston corer, respectively. Analyses of lake sediments have the following objectives: 1) to correlate the geophysical results with the core data to provide a stratigraphic framework for the shallow lake sediments; 2) to constrain past climate variability in this rather poorly investigated area; and 3) to establish a time series of explosive volcanic activity based on the identification and dating of tephra layers in the cores. Initial measurements of magnetic susceptibility, dry density, loss on ignition and XRF scanning indicated a dominance of fine-grained homogeneous diatomaceous sediments cover most of the lake floor. Increasing values in magnetic susceptibility in the upper part of several short cores most likely reflect increased erosion caused by land-use changes during the Spanish colonial period (1522-1822). Results on the two longest cores from the northeastern (355 cm) and southwestern (478 cm) parts of the lake reveal complete Holocene paleoclimate records in both areas that are comparable to other terrestrial and marine records in the Central and South- American tropics (i.e. Cariaco Basin). A lithologic change from homogeneous gyttia (diatomaceous mud) to blue- grayish waxy clay at the bottom of these records marks the Late Pleistocene-Holocene transition as indicated by a radiocarbon dating on plant remains. The latter dense clay forms a distinctive stratigraphic marker in the lake basin. Tephra layers to date were detected in most gravity cores recovered west of Ometepe Island (Volcan Concepcion), and in long records in the northeastern basin (San Antonio Tephra, Masaya volcano, ca. 7,400 interpolated cal

  20. Coupling of Activity at Neighbouring Volcanoes in Iceland: Ground Deformation and Activity at the Bárðarbunga-Tungnafellsjökull and Eyjafjallajökull-Katla Volcano Pairs

    NASA Astrophysics Data System (ADS)

    Parks, M.; Heimisson, E. R.; Sigmundsson, F.; Hooper, A. J.; Ofeigsson, B.; Vogfjord, K. S.; Arnadottir, T.; Dumont, S.; Drouin, V.; Bagnardi, M.; Spaans, K.; Hreinsdottir, S.; Friðriksdóttir, H. M.; Jonsdottir, K.; Guðmundsson, G.; Hensch, M.; Hjaltadottir, S.; Hjartardottir, A. R.; Einarsson, P.; Gudmundsson, M. T.; Hognadottir, T.; Lafemina, P.; Geirsson, H.; Sturkell, E.; Magnússon, E.

    2015-12-01

    Interferometric Synthetic Aperture Radar (InSAR) techniques are used to generate a time series of high-resolution deformation measurements, in the vicinity of two pairs of closely spaced volcanoes in Iceland: Bárðarbunga and Tungnafellsjökull, as well as Eyjafjallajökull and Katla. Following the declaration of Icelandic Volcanoes as a Permanent Geohazard Supersite in 2013, a considerable amount of SAR data was made available for both past and future satellite acquisitions, including new X-band images and historic C-band images. InSAR time series have been formed using these data and compared to other geodetic and microseismic measurements to determine the most likely processes responsible for recently observed deformation and/or seismicity. A comprehensive network of seismometers and continuous GPS stations are already deployed at these volcanoes and a series of campaign GPS measurements have been undertaken since 2010. We present an overview of the temporal variation in InSAR observations and these complementary field based measurements at Bárðarbunga and Tungnafellsjökull from 2014-2015 (covering the recent eruption at Holuhraun and contemporaneous slow collapse of the Bárðarbunga caldera), and Eyjafjallajökull and Katla volcanoes from 2010 onwards, after the 2010 explosive eruption of Eyjafjallajökull. We undertake a joint InSAR-GPS inversion using a Markov-chain Monte Carlo approach. The best-fit source geometries responsible for both the inflation of a 50 km long dyke and simultaneous deflation of the Bárðarbunga central volcano during the 2014-2015 unrest and eruption are found. Using these we calculate the stress changes associated with the Bárðarbunga deformation events and compare our results to the location of earthquake swarms in the vicinity of neighbouring Tungnafellsjökull, where seismic activity increased significantly following the onset of unrest at Bárðarbunga in August 2014. We also determine the optimal source parameters for

  1. Volcano Deformation and Modeling on Active Volcanoes in the Philippines from ALOS InSAR Time Series

    NASA Astrophysics Data System (ADS)

    Morales Rivera, Anieri M.; Amelung, Falk; Eco, Rodrigo

    2015-05-01

    Bulusan, Kanlaon, and Mayon volcanoes have erupted over the last decade, and Taal caldera showed signs of volcanic unrest within the same time range. Eruptions at these volcanoes are a threat to human life and infrastructure, having over 1,000,000 people living within 10 km from just these 4 volcanic centers. For this reason, volcano monitoring in the Philippines is of extreme importance. We use the ALOS-1 satellite from the Japanese Aerospace Exploration Agency (JAXA) to make an InSAR time series analysis over Bulusan, Kanlaon, Mayon, and Taal volcanoes for the 2007-2011 period. Time-dependent deformation was detected at all of the volcanoes. Deformation related to changes in pressurization of the volcanic systems was found on Taal caldera and Bulusan volcanoes, with best fitting Mogi sources located at half-space depths of 3.07 km and 0.5 km respectively.

  2. Attaining high-resolution eruptive histories for active arc volcanoes with argon geochronology

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.

    2012-04-01

    Geochronology of active arc volcanoes commonly illuminates eruptive behavior over tens to hundreds of thousands of years, lengthy periods of repose punctuated by short eruptive episodes, and spatial and compositional changes with time. Despite the >1 Gyr half-life of 40K, argon geochronology is an exceptional tool for characterizing Pleistocene to Holocene eruptive histories and for placing constraints on models of eruptive behavior. Reliable 40Ar/39Ar ages of calc-alkaline arc rocks with rigorously derived errors small enough (± 500 to 3,000 years) to constrain eruptive histories are attainable using careful procedures. Sample selection and analytical work in concert with geologic mapping and stratigraphic studies are essential for determining reliable eruptive histories. Preparation, irradiation and spectrometric techniques have all been optimized to produce reliable, high-precision results. Examples of Cascade and Alaska/Aleutian eruptive histories illustrating duration of activity from single centers, eruptive episodicity, and spatial and compositional changes with time will be presented: (1) Mt. Shasta, the largest Cascade stratovolcano, has a 700,000-year history (Calvert and Christiansen, 2011 Fall AGU). A similar sized and composition volcano (Rainbow Mountain) on the Cascade axis was active 1200-950 ka. The eruptive center then jumped west 15 km to the south flank of the present Mt. Shasta and produced a stratovolcano from 700-450 ka likely rivaling today's Mt. Shasta. The NW portion of that edifice failed in an enormous (>30 km3) debris avalanche. Vents near today's active summit erupted 300-135 ka, then 60-15 ka. A voluminous, but short-lived eruptive sequence occurred at 11 ka, including a summit explosion producing a subplinian plume, followed by >60 km3 andesite-dacite Shastina domes and flows, then by the flank dacite Black Butte dome. Holocene domes and flows subsequently rebuilt the summit and flowed to the north and east. (2) Mt. Veniaminof on

  3. Linear volcanic segments in the central Sunda Arc, Indonesia, identified using Hough Transform analysis: Implications for arc lithosphere control upon volcano distribution

    NASA Astrophysics Data System (ADS)

    Pacey, Adam; Macpherson, Colin G.; McCaffrey, Ken J. W.

    2013-05-01

    Hough Transform analysis is used as an objective means to constrain volcano distribution in the central Sunda Arc, Indonesia. Most volcanoes in the arc define four en echelon, linear segments, each of 500-700 km length. Javan volcanoes that do not lie on these segments either (i) formed at an early stage in the history of the arc and erupted products that are petrologically and geochemically distinct from typical arc magma, or (ii) lie along other mapped structures. The en echelon distribution of volcanoes in the central Sunda Arc is best explained as originating from two possible sources. First, interaction with the subducting Indo-Australian Plate may induce stress in the arc lithosphere generating pathways for magma to exploit. Second, downward flexure of the arc lithosphere, as a result of mantle flow or loading by the arc, would also establish arc-normal tension towards the base of the lithosphere, where magma is supplied to volcanic systems. To the west and east of the central Sunda Arc deviations from the distribution of long, en echelon, linear segments can be understood as responses to specific stress fields in the arc lithosphere of Sumatra and eastern Nusa Tenggara, respectively. Control of volcano distribution by arc lithosphere explains why there are large variations in the depth from volcanoes to the zone of slab seismicity in the central Sunda Arc, where there is little variation in slab geometry or the rate of plate convergence.

  4. Active volcanoes observed through Art: the contribution offered by the social networks

    NASA Astrophysics Data System (ADS)

    Neri, Marco; Neri, Emilia

    2015-04-01

    Volcanoes have always fascinated people for the wild beauty of their landscapes and also for the fear that they arouse with their eruptive actions, sometimes simply spectacular, but other times terrifying and catastrophic for human activities. In the past, volcanoes were sometimes imagined as a metaphysical gateway to the otherworld; they have inspired the creation of myths and legends ever since three thousand years ago, also represented by paintings of great artistic impact. Modern technology today offers very sophisticated and readily accessed digital tools, and volcanoes continue to be frequently photographed and highly appreciated natural phenomena. Moreover, in recent years, the spread of social networks (Facebook, Twitter, YouTube, Instagram, etc.) have made the widespread dissemination of graphic contributions even easier. The result is that very active and densely inhabited volcanoes such as Etna, Vesuvius and Aeolian Islands, in Italy, have become among the most photographed subjects in the world, providing a popular science tool with formidable influence and usefulness. The beauty of these landscapes have inspired both professional artists and photographers, as well as amateurs, who compete in the social networks for the publication of the most spectacular, artistic or simply most informative images. The end result of this often frantic popular scientific activity is at least two-fold: on one hand, it provides geoscientists and science communicators a quantity of documentation that is almost impossible to acquire through the normal systems of volcano monitoring, while on the other it raises awareness and respect for the land among the civil community.

  5. Volcanoes: Nature's Caldrons Challenge Geochemists.

    ERIC Educational Resources Information Center

    Zurer, Pamela S.

    1984-01-01

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

  6. Attempt of volcanomagnetic change detection by repeated aeromagnetic survey aeromagnetic survey on Aso and Kuju volcano, central Kyushu Japan -

    NASA Astrophysics Data System (ADS)

    Utsugi, M.; Tanaka, Y.; Kagiyama, T.; Okubo, A.

    2006-12-01

    Recently, geomagnetic field observation is successfully applied to many active volcanos to detect the volcano- magnetic changes. These observations are usually based on the continuous or repeated observation stations setting on the ground near the active area. From these observations, we can obtain high accurate information about the temporal geomagnetic field changes. But we can obtain only limited information about the special distribution of field changes. To interpret the geomagnetic field changes to underground heat transfer, we have to know the special distribution of the geomagnetic changes. To obtain the detailed information about the spatial distribution, aeromagnetic survey is usually used. In our study, we tried to use this method to detect the volcanomagnetic change. The main problem of aeromagnetic repeated observation is the difficulty of the observation point control. In the two flights, it is impossible that quite the same place flies. So that, it is very difficult to separate a change according to the volcanic activity and a spatial change. But, if we know detailed 3-D distribution of geomagnetic field and we can estimate the field intensity on the arbitrary point, we can correct the spatial variation of the repeated aeromagnetic survey data caused by the difference of flight position, and it may be possible to detect the field changes associated with the volcanic activities. For this purpose, we made very high density and low altitude helicopter-borne aeromagnetic survey on Aso and Kuju volcano in July 2002 and Dec. 2004. Each observation was done by a different approach. On Aso volcano, an extremely high density aeromagnetic observation was carried out. The survey area was selected as NS1200 x EW1200 x 300m region above the Nakadake crater which is the most active area on Aso volcano. The flight was made in 8 heights. The total numbers of measurements were about 8200. Based on the equivalent anomaly method, which is usually used to calculate the

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

    PubMed

    Yang, Hong-Mei; Lou, Kai; Sun, Jian; Zhang, Tao; Ma, Xiao-Long

    2012-02-01

    The Usu mud volcanoes are the largest group of terrestrial mud volcanoes in China. The volcanoes are located in a typical arid and semi-arid region, and the group consists of 36 erupting active mud volcanoes. In this study, the prokaryotic diversity and community structure in the sediment of an active mud volcano were investigated by constructing bacterial and archaeal clone libraries of the 16S rRNA gene. A total of 100 bacterial and 100 archaeal clones were analysed and found to comprise 11 and 7 distinct phylotypes, respectively. The bacterial phylotypes were classified into three phyla (Proteobacteria, Actinobacteria, and Fusobacteria). Of these, Proteobacteria were the most abundant bacterial group, with Deltaproteobacteria dominating the sediment community, and these were affiliated with the order Desulfuromonadales. The archaeal phylotypes were all closely related to uncultivated species, and the majority of the members were related to the orders Methanosarcinales and Halobacteriales of the Euryarchaeota originating from methane hydrate bearing or alkaline sediments. The rest of the archaeal phylotypes belonged to the phylum Crenarchaeota, with representatives from similar habitats. These results suggested that a large number of novel microbial groups and potential methanogenesis may exist in this unique ecosystem. PMID:21656823

  8. Bibliography for Hayes, Spurr, Crater Peak, Redoubt, Iliamna, Augustine, Douglas, and Aniakchak volcanoes, Alaska

    USGS Publications Warehouse

    Lemke, K.J.; May, B.A.; Vanderpool, A.M.

    1995-01-01

    Alaska has more than 40 active volcanoes, many of which are close to the major population centers of south-central Alaska. This bibliography was compiled to assist in the preparation of volcano hazard evaluations at Cook Inlet volcanoes. It lists articles, reports, and maps about the geology and hydrology of Hayes, Spurr, Redoubt, Iliamna, Augustine, and Douglas volcanoes in the Cook Inlet region as well as Aniakchak Volcano on the Alaska Peninsula. References on the biology and archaeology of areas surrounding each volcano also are included because they may provide useful background information.

  9. Evaluating life-safety risk of fieldwork at New Zealand's active volcanoes

    NASA Astrophysics Data System (ADS)

    Deligne, Natalia; Jolly, Gill; Taig, Tony; Webb, Terry

    2014-05-01

    Volcano observatories monitor active or potentially active volcanoes. Although the number and scope of remote monitoring instruments and methods continues to grow, in-person field data collection is still required for comprehensive monitoring. Fieldwork anywhere, and especially in mountainous areas, contains an element of risk. However, on volcanoes with signs of unrest, there is an additional risk of volcanic activity escalating while on site, with potentially lethal consequences. As an employer, a volcano observatory is morally and sometimes legally obligated to take reasonable measures to ensure staff safety and to minimise occupational risk. Here we present how GNS Science evaluates life-safety risk for volcanologists engaged in fieldwork on New Zealand volcanoes with signs of volcanic unrest. Our method includes several key elements: (1) an expert elicitation for how likely an eruption is within a given time frame, (2) quantification of, based on historical data when possible, given a small, moderate, or large eruption, the likelihood of exposure to near-vent processes, ballistics, or surge at various distances from the vent, and (3) estimate of fatality rate given exposure to these volcanic hazards. The final product quantifies hourly fatality risk at various distances from a volcanic vent; various thresholds of risk (for example, zones with more than 10-5 hourly fatality risk) trigger different levels of required approval to undertake work. Although an element of risk will always be present when conducting fieldwork on potentially active volcanoes, this is a first step towards providing objective guidance for go/no go decisions for volcanic monitoring.

  10. Geothermal activities in Central America

    SciTech Connect

    Whetten, J.T.; Hanold, R.J.

    1985-09-11

    The Agency for International Development is funding a new program in energy and minerals for Central America. Geothermal energy is an important component. A country-wide geothermal assessment has started in Honduras, and other assessment activities are in progress or planned for Costa Rica, El Salvador, Guatemala, and Panama. Instrumentation for well logging has been provided to Costa Rica, and a self-contained logging truck will be made available for use throughout Central America. An important objective of this program is to involve the private sector in resource development. 4 refs., 3 figs.

  11. Hydrogochemical tools for monitoring active volcanoes: Applications to El Chichón volcano, México.

    NASA Astrophysics Data System (ADS)

    Armienta, M. A.; de La Cruz-Reyna, S.; Ramos, S.; Morton, O.; Ceniceros, N.; Aguayo, A.; Cruz, O.

    2010-03-01

    In 1982, a series of eruptions resulted in the worst disaster linked with volcanic activity in México. The characteristics of the phenomena together with a lack of prevention measures resulted in approximately 2000 deaths. An important aspect to prevent disasters is a thorough knowledge and monitoring of the potentially destructive natural phenomena. Monitoring the activity of dormant or active volcanoes by various methods is thus a key measure to estimate the hazard and design adequate risk reduction measures. Despite of the 1982 volcanic disaster, until only a few years, hydrogeochemical monitoring was the only regular surveillance of El Chichón post-eruptive activity. The first samples of the crater-lake water were collected by Casadevall et al. in 1983. Since 1985, a systematic sampling and chemical analyses program has been carried out by the Geophysics Institute in collaboration with local authorities from the State of Chiapas. Chemical analyses of main ions and Rare Earth elements (REE) are performed in the Laboratorio de Química Analítica and Laboratorio ICP-MS of the Instituto de Geofísica, UNAM. Results are interpreted considering the physico-chemical changes that may be recognized as precursors of volcanic activity. The problem is difficult because at least two main water reservoirs feed the crater lake; besides, dissolution of acid volcanic gases, water-rock interactions and geochemical processes among dissolved species have resulted in a complex chemical behavior of the lake-water along the years. The calculated degree of neutralization, pH values, and chloride and sulfate concentrations of samples taken at different dates result in a classification of the volcano as active or inactive according to the method developed by Varekamp. A pH of 0.5, very high conductivity and a temperature of about 50°C characterized the first years following the eruptions. An overall decrease on the temperature and ionic concentrations, along with a less acid p

  12. Elevated Seismic Activity Beneath the Slumbering Morne aux Diables Volcano, Northern Dominica and the Monitoring Role of the Seismic Research Centre

    NASA Astrophysics Data System (ADS)

    Watts, R. B.; Robertson, R. E.; Abraham, W.; Cole, P.; de Roche, T.; Edwards, S.; Higgins, M.; Johnson, M.; Joseph, E. P.; Latchman, J.; Lynch, L.; Nath, N.; Ramsingh, C.; Stewart, R. C.

    2012-12-01

    Since June 2009, periods of elevated seismic activity have been experienced around the flanks of Morne Aux Diables Volcano in northern Dominica. This long-dormant volcano is a complex of 7 andesitic lava domes with a central depression where a cold soufrière is evident. Prior to this activity, seismicity was very quiet except for a short period in 2000 and an intense short-lived swarm in April 2003. The most recent earthquake activity has been regularly felt by residents in villages on all flanks of the complex. In Dec 09/Jan10, scientists from the Seismic Research Centre (SRC), based in Trinidad & Tobago, in collaboration with staff of the Office of Disaster Management (ODM) and Dominica Public Seismic Network (DPSN) improved the monitoring capacity around this volcano from 1 to 7 seismic stations. Earthquakes are determined to be volcano-tectonic in nature and located at shallow depths (<4 km) beneath the central depression. Additionally, in Jan/Feb 10 geothermal sampling was undertaken and 2 permanent GPS sites were deployed. Public information leaflets prepared by SRC scientists using a "Question & Answer" format have been distributed to concerned citizens whilst many public meetings were carried out by ODM staff. Field investigations indicate that the previous Late Pleistocene activity of Morne Aux Diables switched from Pelèan dome growth and gravitational collapse to more explosive pumice-falls and associated ignimbrites, both styles forming extensive pyroclastic fans around the central complex. The town of Portsmouth is located on one of these fans ~5 km southwest of the central depression. Sporadic, short bursts of seismic activity continue at the time of writing.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  14. Methods of InSAR atmosphere correction for volcano activity monitoring

    USGS Publications Warehouse

    Gong, W.; Meyer, F.; Webley, P.W.; Lu, Zhiming

    2011-01-01

    When a Synthetic Aperture Radar (SAR) signal propagates through the atmosphere on its path to and from the sensor, it is inevitably affected by atmospheric effects. In particular, the applicability and accuracy of Interferometric SAR (InSAR) techniques for volcano monitoring is limited by atmospheric path delays. Therefore, atmospheric correction of interferograms is required to improve the performance of InSAR for detecting volcanic activity, especially in order to advance its ability to detect subtle pre-eruptive changes in deformation dynamics. In this paper, we focus on InSAR tropospheric mitigation methods and their performance in volcano deformation monitoring. Our study areas include Okmok volcano and Unimak Island located in the eastern Aleutians, AK. We explore two methods to mitigate atmospheric artifacts, namely the numerical weather model simulation and the atmospheric filtering using Persistent Scatterer processing. We investigate the capability of the proposed methods, and investigate their limitations and advantages when applied to determine volcanic processes. ?? 2011 IEEE.

  15. Identifying deformation styles and causes at two deforming volcanoes of the Central Main Ethiopian Rift with seismic anisotropy

    NASA Astrophysics Data System (ADS)

    Nowacki, Andy; Wilks, Matthew; Kendall, J.-Michael; Biggs, Juliet; Ayele, Atalay; Tulu, Beshahe; James, Wookey

    2016-04-01

    The Main Ethiopian Rift (MER) has undergone extension since ˜8 Ma, and whilst large border faults were active until later stages, since then (2 Ma) seemingly most extension has been via the Wonji Fault Belt (WFB), a series of en-echelon faults perpendicular to current spreading, which possibly focus around magmatic centres. Two such centres are Corbetti and Aluto volcanoes in the central MER. They have shown significant (>5 cm) uplift and subsidence for at least five years, probably erupted in the Holocene, and are geothermal sites. They are presumed therefore to play an active rôle in present-day extension along the rift, via magma injection and brittle deformation; yet a detailed physical explanation of their behaviour remains elusive. We report results from a recent combined seismic-geodetic study (ARGOS) of these areas, focussing on the seismic anisotropy revealed. We confirm that both volcanoes are seismically active, with events located beneath the edifice having mean local magnitude mL = 1.0. Beneath Aluto, there are two main clusters of activity: (1) at depths 5-10 km below sea level (bsl), and (2) between ‑2 and 0 km bsl. Focal mechanisms show predominantly normal faulting on fault planes striking north-northeast (NNE), and event locations cluster along a similar trend. The identification of the WFB in this region is debated, but we show that only the deepest (5-15 km) events occur along the northeast-trending faults with outcropping to the east. Shear wave splitting of over 5 % is present, and appears to be confined to the top 5 km, since little depth dependence is shown. Fast shear wave orientations have again a NNE trend. These lines of evidence indicate that current seismic deformation, and aligned structures in the top few km, act in response to the current stress field, and not pre-existing features. Any magmatic emplacement occurring above 15 km is likely not as dykes, as these would create large seismic anisotropy at these depths which is not

  16. Dante's volcano

    NASA Astrophysics Data System (ADS)

    1994-09-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  17. Dante's Volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  18. Inside active volcanoes; an exhibit on the move!

    USGS Publications Warehouse

    Fiske, R.S.

    1990-01-01

    All of us are aware of the emphasis currently being placed in the United States on science education and public understanding of science. Most of this emphasis is directed toward mass audiences through book publications, school curricula, and television programs; sadly, most of it deals with non-earth science topics. In an effort to take advantage of this awakened consciousness and to highlight the earth sciences, the Smithsonian Institution and the U.S Geological Survey joined forces to prepare a traveling exhibit on volcanoes that is currently touring the country. This note will serve to bring you up to date on the progress of this exhibit as it reaches the mid-point of its tour. 

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

    NASA Astrophysics Data System (ADS)

    Rodriguez, L. A.

    2010-12-01

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

  20. Methanogenic activity and diversity in the centre of the Amsterdam Mud Volcano, Eastern Mediterranean Sea.

    PubMed

    Lazar, Cassandre Sara; John Parkes, R; Cragg, Barry A; L'Haridon, Stephane; Toffin, Laurent

    2012-07-01

    Marine mud volcanoes are geological structures emitting large amounts of methane from their active centres. The Amsterdam mud volcano (AMV), located in the Anaximander Mountains south of Turkey, is characterized by intense active methane seepage produced in part by methanogens. To date, information about the diversity or the metabolic pathways used by the methanogens in active centres of marine mud volcanoes is limited. (14)C-radiotracer measurements showed that methylamines/methanol, H(2)/CO(2) and acetate were used for methanogenesis in the AMV. Methylotrophic methanogenesis was measured all along the sediment core, Methanosarcinales affiliated sequences were detected using archaeal 16S PCR-DGGE and mcrA gene libraries, and enrichments of methanogens showed the presence of Methanococcoides in the shallow sediment layers. Overall acetoclastic methanogenesis was higher than hydrogenotrophic methanogenesis, which is unusual for cold seep sediments. Interestingly, acetate porewater concentrations were extremely high in the AMV sediments. This might be the result of organic matter cracking in deeper hotter sediment layers. Methane was also produced from hexadecanes. For the most part, the methanogenic community diversity was in accordance with the depth distribution of the H(2)/CO(2) and acetate methanogenesis. These results demonstrate the importance of methanogenic communities in the centres of marine mud volcanoes. PMID:22458514

  1. Central Asia Active Fault Database

    NASA Astrophysics Data System (ADS)

    Mohadjer, Solmaz; Ehlers, Todd A.; Kakar, Najibullah

    2014-05-01

    The ongoing collision of the Indian subcontinent with Asia controls active tectonics and seismicity in Central Asia. This motion is accommodated by faults that have historically caused devastating earthquakes and continue to pose serious threats to the population at risk. Despite international and regional efforts to assess seismic hazards in Central Asia, little attention has been given to development of a comprehensive database for active faults in the region. To address this issue and to better understand the distribution and level of seismic hazard in Central Asia, we are developing a publically available database for active faults of Central Asia (including but not limited to Afghanistan, Tajikistan, Kyrgyzstan, northern Pakistan and western China) using ArcGIS. The database is designed to allow users to store, map and query important fault parameters such as fault location, displacement history, rate of movement, and other data relevant to seismic hazard studies including fault trench locations, geochronology constraints, and seismic studies. Data sources integrated into the database include previously published maps and scientific investigations as well as strain rate measurements and historic and recent seismicity. In addition, high resolution Quickbird, Spot, and Aster imagery are used for selected features to locate and measure offset of landforms associated with Quaternary faulting. These features are individually digitized and linked to attribute tables that provide a description for each feature. Preliminary observations include inconsistent and sometimes inaccurate information for faults documented in different studies. For example, the Darvaz-Karakul fault which roughly defines the western margin of the Pamir, has been mapped with differences in location of up to 12 kilometers. The sense of motion for this fault ranges from unknown to thrust and strike-slip in three different studies despite documented left-lateral displacements of Holocene and late

  2. Water composition in the unsaturated zone at Sete Cidades central volcano (S. Miguel, Azores, Portugal)

    NASA Astrophysics Data System (ADS)

    Cruz, J.; Silva, M.; Mendonça, J.; Dias, I.; Prudêncio, I.

    2009-04-01

    A field study was developed at Sete Cidades, the westernmost of the three active composite volcanoes that dominate the geology of São Miguel, the largest of the nine islands from the Azores archipelago. Research methodology comprehends the characterization of soil-water composition at several depths, sampled by means of ceramic suction cups. Previously to their installation, cups were all submitted to several stages of washing, first in the laboratory with supra pure water, until aliquot conductivity stabilizes, and after in the field. This study was planned in order to study the water pollution due to agriculture, one of the main economic activities in the Azores, as shown by the gross value added to regional product. The negative effects of groundwater pollution due to agriculture have been reported in the majority of the nine islands, reflected by high contents of nitrogen species, derived from the inadequate use of synthetic and organic fertilizers, as well as from animal wastes leaching, or also by microbiology parameters. The relation between water pollution and agriculture results in some cases in the failure to comply regarding EU and national water quality regulations, through quality deterioration and compromising groundwater as strategic natural resource in the Azores. The studied area corresponds to Sete Cidades volcano caldera, a 5 km-diameter circular shaped depression, contoured by steep walls from 30 m high up to 400 m. In order to characterize unsaturated water composition in the caldera floor, five pasture locations were selected and monitored, as well as one site with the same physical conditions, but without agricultural activity. From the 5 pasture lands we discuss further results obtained in the so-called Pavão I (Pa I), which corresponds to the most extensive data set. On this site, 6 suction cups were installed, at depths 0.35 m, 0.7 m, 1 m, 1.3 m, 1.6 m and 1.9 m. In the site without agricultural activity, in the vicinity of Sete Cidades

  3. Constrains on the Latest Volcanic Eruptions in Eastern-Central Europe: Zircon Geochronology and Magma Residence Time at the Ciomadul Volcano.

    NASA Astrophysics Data System (ADS)

    Harangi, S.; Lukács, R.; Dunkl, I.; Molnár, K.; Schmitt, A. K.; Kiss, B.

    2014-12-01

    Evaluation of volcanic hazard is often difficult, particularly at those areas, where no volcanic events have been documented in the historical time or even longer. Here, we present new geochronological data to demonstrate that relatively young volcanism occurred in eastern-central Europe, at the Ciomadul volcano (southeast Carpathians, Romania) and there is a potential for future rejuvenation. The eruption ages of the Ciomadul are constrained by (U-Th)/He zircon dating corrected for U-series disequilibrium and this suggests that the volcanic activity occurred from 150 ka to 32 ka. Following a lava dome building stage, a more explosive eruption phase took place at 50-32 ka. Subplinian to plinian eruptions produced volcanic ash clouds that blanketed extended areas. The U-Th and U-Pb age spectra of the zircons from the 50-32 ka volcanic rocks ranges over 300 ka and is thus indicative of a long-lasting intrusive body beneath the volcano. Interior-rim age difference within individual zircons is as much as 340-88 ka. Thus, a subterraneous magma system was already under construction ca. 150-200 ka before the onset of volcanic eruptions. The peak zircon crystallization age falls between 220-100 ka, and there are only sparse age data <100 ka indicating that conditions became unfavourable for zircon crystallization, possibly due to sluggish precipitation at low temperatures or complete solidification within some parts of the magma system. Nevertheless, rim-analysis (outer 4 μm) of the youngest, 32 ka zircons shows that crystallization occurred also at 60-80 ka, but this still precedes the eruption age by about 30-40 ka. All samples contain zircons with widely differing ages which cover the entire 300 ka period of magma evolution at Ciomadul. These data reflect that a melt-bearing crystal mush body could have continuously existed beneath the volcano. Intermittent injections of hotter magma into the cold crystal mush could help to maintain the magma system over 100's ka

  4. Crustal structure of east central Oregon: relation between Newberry Volcano and regional crustal structure

    USGS Publications Warehouse

    Catchings, R.D.; Mooney, W.D.

    1988-01-01

    A 180-km-long seismic refraction transect from the eastern High Cascades, across Newberry Volcano, to the eastern High Lava Plains is used to investigate the subvolcanic crustal and upper mantle velocity structure there. Near-surface volcanic flows and sedimentary debris (1.6-4.7 km/s), ranging from 3 to 5 km in thickness, overlie subvolcanic Basin and Range structures. East and west of Newberry Volcano, the subvolcanic basement (5.6 km/s) has been downwarped, producing 5-km-deep basins. The midcrust (8- to 28-km depth) is characterized by velocities ranging from 6.1 to 6.5 km/s and varies laterally in thicknesses. The lower crust is characterized by an unusually high velocity (about 7.4 km/s), and its geometry mirrors the subvolcanic basement geometry. The Moho is located at a depth of 37 km and represents a transition to an upper mantle velocity of 8.1 km/s. The shallow subsurface (1.2 km) beneath Newberry Volcano is characterized by high-velocity 5.6 km/s, versus 4.1 km/s for the surrounding area) intrusions and appears to be located on a basement high. Beneath the seismic refraction array at Newberry Volcano, an absence of low-velocity anomalies suggests that large silicic magma chambers do not exist in the upper crust, but apparent high attenuation of the seismic wave field may be consistent with either partial melts in small volumes, elevated crustal temperatures, and/or poor geophone-recording site coupling. -Authors

  5. Eruptive history, current activity and risk estimation using geospatial information in the Colima volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Camarena-Garcia, M.; Nunez-Cornu, F. J.; Flores-Peña, S.

    2013-12-01

    Colima volcano, also known as Volcan de Fuego (19 30.696 N, 103 37.026 W), is located on the border between the states of Jalisco and Colima, and is the most active volcano in Mexico. In January 20, 1913, Colima had its biggest explosion of the twentieth century, with VEI 4, after the volcano had been dormant for almost 40 years. In 1961, a dome reached the northeastern edge of the crater and started a new lava flow, and from this date maintains constant activity. In February 10, 1999, a new explosion occurred at the summit dome. The activity during the 2001-2005 period was the most intense, but did not exceed VEI 3. The activity resulted in the formation of domes and their destruction after explosive events. The explosions originated eruptive columns, reaching altitudes between 4,500 and 9,000 masl, further pyroclastic flows reaching distances up to 3.5 km from the crater. During the explosive events, ash emissions were generated in all directions reaching distances up to 100 km, slightly affecting the nearby villages: Tuxpan, Tonila, Zapotlan, Cuauhtemoc, Comala, Zapotitlan de Vadillo and Toliman. During 2005 to July 2013, this volcano has had an intense effusive-explosive activity; similar to the one that took place during the period of 1890 through 1905. That was before the Plinian eruption of 1913, where pyroclastic flows reached a distance of 15 km from the crater. In this paper we estimate the risk of Colima volcano through the analysis of the vulnerability variables, hazard and exposure, for which we use: satellite imagery, recurring Fenix helicopter over flights of the state government of Jalisco, the use of the images of Google Earth and the population census 2010 INEGI. With this information and data identified changes in economic activities, development, and use of land. The expansion of the agricultural frontier in the lower sides of the volcano Colima, and with the advancement of traditional crops of sugar cane and corn, increased the growth of

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

    NASA Astrophysics Data System (ADS)

    Gencalioglu-Kuscu, Gonca

    2011-11-01

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

  7. Time Variation of Seismic Anisotropy, Stress and Cracks on Active Volcanoes (Invited)

    NASA Astrophysics Data System (ADS)

    Savage, M. K.

    2013-12-01

    We summarize measurements of seismic anisotropy and its relation to other geophysical measurements of stress and cracks on eleven active volcanoes; Unzen (Unz), Sakurajima (Sak), Aso, Asama (Asm) and Kirishima (Kir) in Japan; Okmok (Okm) in Alaska, Ruapehu (Rua) and Tongariro (Ton) in New Zealand, Soufriere Hills (Sou) in Montserrat, Kilauea (Kil) in Hawaii and Piton de la Fournaise (PdF) in La Reunion. We used the MFAST shear wave splitting computer code, an objective code that is fully automatic except for the S arrival pick. Fast polarization directions (phi) should be parallel to cracks and hence the maximum horizontal stress direction. Time delays (dt) increase with path length and percent anisotropy, usually related to crack density. Where possible we used S waves from deep earthquakes to ensure that the movement of the earthquakes was not correlated with the volcanic activity. At some volcanoes we used families of repeating events with similar waveforms and at most volcanoes we also computed splitting at earthquakes local to the volcano. We compared the phi and dt variation in time to eruption occurrences and to other available parameters including seismicity rate, b-values, focal mechanisms, isotropic velocity changes from noise cross-correlation, Vp/Vs ratios, Geodetic measurements such as GPS and tilt, and gas flux. All volcanoes had some stations with excellent shear wave arrivals that yielded measureable splitting. Individual measurements showed scatter in most areas, but at most of the volcanoes, moving averages of phi or dt (or both) yielded time variations that correlated with other measurements related to volcanic activity or to stress changes or changes in crack-filling material such as gas flux. The multiplet studies did not yield slowly varying splitting but instead showed distinct jumps in splitting parameters at various times, which appears to be caused in part by cycle skipping. Time resolution of changes depends on the seismicity available

  8. Prokaryotic community structure and diversity in the sediments of an active submarine mud volcano (Kazan mud volcano, East Mediterranean Sea).

    PubMed

    Pachiadaki, Maria G; Lykousis, Vasilios; Stefanou, Euripides G; Kormas, Konstantinos A

    2010-06-01

    We investigated 16S rRNA gene diversity at a high sediment depth resolution (every 5 cm, top 30 cm) in an active site of the Kazan mud volcano, East Mediterranean Sea. A total of 242 archaeal and 374 bacterial clones were analysed, which were attributed to 38 and 205 unique phylotypes, respectively (> or = 98% similarity). Most of the archaeal phylotypes were related to ANME-1, -2 and -3 members originating from habitats where anaerobic oxidation of methane (AOM) occurs, although they occurred in sediment layers with no apparent AOM (below the sulphate depletion depth). Proteobacteria were the most abundant and diverse bacterial group, with the Gammaproteobacteria dominating in most sediment layers and these were related to phylotypes involved in methane cycling. The Deltaproteobacteria included several of the sulphate-reducers related to AOM. The rest of the bacterial phylotypes belonged to 15 known phyla and three unaffiliated groups, with representatives from similar habitats. Diversity index H was in the range 0.56-1.73 and 1.47-3.82 for Archaea and Bacteria, respectively, revealing different depth patterns for the two groups. At 15 and 20 cm below the sea floor, the prokaryotic communities were highly similar, hosting AOM-specific Archaea and Bacteria. Our study revealed different dominant phyla in proximate sediment layers. PMID:20370830

  9. BrO/SO2 ratios at Popocatepetl volcano during increased activity in 2012

    NASA Astrophysics Data System (ADS)

    Fickel, M.; Delgado Granados, H.

    2012-12-01

    Since its reactivation in 1994 after many decades of inactivity, Popocatepetl volcano has been showing long periods of quiescent degassing and some events of intensified activity in connection with dome building and destruction processes. During a period of increased activity of the volcano, which began in April 2012, mobile ultraviolet DOAS measurements and stationary DOAS scans were performed to quantify SO2 fluxes and BrO/SO2 ratios within the volcanic plume. The results of these measurements are presented in the context of the volcanic activity, which consisted of increased emission of gas and ash and Vulcanian type explosions. In general, SO2 emissions were high during the period April-June 2012 and so the BrO emissions, however, the BrO/SO2 ratios did not change strongly before, during and after the increased activity.

  10. Anomalous Change of Diffuse CO2 Emission Rates at San Salvador volcano, El Salvador, Central America: a premonitory geochemical signature of magmatic and/or tectonic reactivation?

    NASA Astrophysics Data System (ADS)

    Perez, N.; Salazar, J.; Hernandez, P.; Soriano, T.; Barahona, F.; Cartagena, R.; Olmos, R.; Lopez, D.

    2002-12-01

    San Salvador volcano is located towards the southern part of the Central American graben. The most recent magmatic activity was mainly focused on the volcano NW flank forming monogenetic explosion craters, cinder cones, and lava flows. Flank vents continue to erupt at a rate of once every 82 yrs with the last eruption in 1917 (Sofield, 1999). The city of San Salvador, with a population 1.7 million located at the skirts of the volcano, will be at high risk if an eruption occurs. The purpose of this work is to provide a multidisciplinary approach for the volcanic surveillance by means of introducing geochemical continuous monitoring of diffuse CO2 and H2S emission rates. Soil CO2 and H2S efflux are continuously monitored at Cerro La Hoya, which is located at San Salvador volcano southern flank, by means of a soil gas efflux continuous monitoring station. Since Nov.11, 2001, until Aug.30, 2002, about 6,800 observations of soil gas efflux and meteorological measurements had been recorded. Soil H2S efflux values were negligible during this period. On the contrary, two distinct diffuse CO2 degassing periods have been observed: (1) a stationary period from Nov. 11 to Dec. 27, 2001, and (2) a clear increasing trend period from Dec. 28, 2001, up to date. From Nov.11 to Dec.27, 2001, CO2 efflux showed an average of 700 gm-2d-1 peaking values up to 1,194 gm-2d-1. From Dec.28, 2001, to Aug.30, 2002, CO2 efflux showed an average of 7,435 gm-2d-1 peaking values up to 45,285 gm-2d-1. Soil temperature showed similar average and peak values for both periods. It is quite evident that this anomalous change of CO2 efflux rate at San Salvador is not driven by meteorological fluctuations. Therefore, this anomalous change of diffuse CO2 emission should be related to an increase of CO2 pressure in the volcanic-hydrothermal system. This increase of fluid pressure could be related to subsurface strain/stress changes, which might be taking place due to either magmatic or tectonic

  11. Explosive Activity at Tungurahua Volcano: Analysis of Seismic and Infrasonic Data from 2006 - 2011

    NASA Astrophysics Data System (ADS)

    Steele, A. L.; Ruiz, M. C.; Lyons, J. J.

    2012-12-01

    Tungurahua is an active, steep-sided andesitic stratovolcano, located in central Ecuador. Historic eruptions are characterized by strong explosions, lava and pyroclastic flows, lahars and tephra fallout. After 75 years of quiescence, a renewed phase of explosive activity began in October 1999. Since, Tungurahua has experienced a series of eruptive cycles, with almost continuous activity separated by only short periods (months) of repose. We apply several statistical techniques to a continuous catalog of over 4500 volcanic explosions, recorded between July 2006 and May 2011. Reduced amplitudes and energies are calculated for each event using four collocated broadband seismic and infrasound sensors. An initial time series analysis isolates 8 phases of activity: Jul-Aug 2006, Feb-Apr 2007, Jul 2007-Feb 2008, Mar 2008-Jun 2009, Jan-Mar 2010, May-Jul 2010, Nov-Dec 2010 and Apr-May 2011. Small temporal changes in the volcanic eruption mechanism across successive episodes are identified by a lack of dependency in event rate auto-correlation and a continuous fluctuation in the proxy b-value of moving-window, frequency-amplitude distributions. We highlight the May-July 2010 episode because it is statistically distinct from the other periods of explosive activity. Peak explosion event rate during this time is approximately six times that of any other episode across the observation period (max ~ 242 events; 31 May 2010), while cumulative daily seismo-acoustic explosion energies are at least an order of magnitude greater. The coefficient of variation (Cv = σ/μ, where; σ is the standard deviation; and μ is the mean repose time of explosions) is used to show a strong clustering of events with time (episodes 1-5 & 7-8 = Cv ~ 2-5) and not representative of a Poisson controlled process. A Cv ~ 13.7 in May-July 2010 (episode 6) further highlights the anomalous nature of activity during this period. The volcano acoustic-seismic ratio (VASR, or η), the ratio of elastic energy

  12. Perception of volcanic eruption as agent of change on Merapi volcano, Central Java

    NASA Astrophysics Data System (ADS)

    Dove, Michael R.

    2008-05-01

    Events like volcanic eruptions challenge equilibrium models of nature. This is a study of the perceptions of eruptions as agents of change, taking Mt. Merapi in Central Java as a case study. Villagers living on Merapi have developed a system of religious belief, and a system of agro-ecological practices, that 'domesticates' the volcanic hazard. The villagers view eruptions as agents of change, often change for the good. The Indonesian government, on the other hand, technologizes and exoticizes the volcanic hazard, and conceptually and materially separates it from the realm of civil society. The state focuses its attention exclusively on intermittent moments of heightened volcanic activity, whereas the villagers focus their attention on the much longer interim periods when there is little or no such activity. This case study shows that not just the perception of risk, but the very concept of risk itself can vary. The cultural production of such concepts co-evolves with natural patterns of perturbation.

  13. Catalogue of Icelandic Volcanoes

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Gudmundsson, Magnus T.; Vogfjord, Kristin; Pagneux, Emmanuel; Oddsson, Bjorn; Barsotti, Sara; Karlsdottir, Sigrun

    2016-04-01

    The Catalogue of Icelandic Volcanoes is a newly developed open-access web resource in English intended to serve as an official source of information about active volcanoes in Iceland and their characteristics. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the effort of FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite. Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene (the time since the end of the last glaciation - approximately the last 11,500 years). In the last 50 years, over 20 eruptions have occurred in Iceland displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and the distribution lava and tephra. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in numerous scientific papers and other publications. In 2010, the International Civil Aviation Organisation (ICAO) funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU through the FP7 project FUTUREVOLC. The Catalogue of Icelandic Volcanoes is a collaboration of the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Civil Protection Department of the National Commissioner of the Iceland Police, with contributions from a large number of specialists in Iceland and elsewhere. The Catalogue is built up of chapters with texts and various

  14. Magnetic precursors to the 2013 eruptive activity at Popocatepetl Volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Martin, A.; Gonzalez, E.; Cifuentes-Nava, G.; HernaNdez-Quintero, J.; Flores, A.

    2013-12-01

    Popocateptl volcano, 60km from Mexico City, has been erupting since 1994 with periods of more intense activity. Volcanomagnetic signals at Popocatepetl have been correlated with different volcanic phenomena especially ascent of several magma batches in pulses lasting several hours that precede increasing seismicity at the volcano. Data from the TL magnetic station on the northern flank of the volcano at 4000masl and from the CPX station at the same altitude on the southwestern flank are processed with the data from the TEO base station (weighted differences) in order to remove signals not associated with the volcano. Short term negative volcanic anomalies around 10nT preceded sharp increases in seismicity and copious ash emission during April and May 2013. They were correlated with periods of harmonic tremor and interpreted as new ascending magma batches, below the Curie point. A longer term descending magnetic trend from February on, is of thermomagnetic origen and is associated with the more mafic andesite compositions of the ash which contain higher MgO and are consistent with influx of deeper magma at higher magmatic temperatures. Sharp positive magnetic peaks are related both with explosions and seismic events, while sustained steps of positive anomalies are related with dome growth and cooling

  15. A Scientific Excursion: Volcanoes.

    ERIC Educational Resources Information Center

    Olds, Henry, Jr.

    1983-01-01

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

  16. 2008 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2011-01-01

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

  17. 2007 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Neal, Christina A.; Dixon, James P.; Malik, Nataliya; Chibisova, Marina

    2011-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest at or near nine separate volcanic centers in Alaska during 2007. The year was highlighted by the eruption of Pavlof, one of Alaska's most frequently active volcanoes. Glaciated Fourpeaked Mountain, a volcano thought to have been inactive in the Holocene, produced a phreatic eruption in the autumn of 2006 and continued to emit copious amounts of steam and volcanic gas into 2007. Redoubt Volcano showed the first signs of the unrest that would unfold in 2008-09. AVO staff also participated in hazard communication and monitoring of multiple eruptions at seven volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  18. Dueling Volcanoes: How Activity Levels At Kilauea Influence Eruptions At Mauna Loa

    NASA Astrophysics Data System (ADS)

    Trusdell, F.

    2011-12-01

    The eruption of Kilauea at Pu`u `O`o is approaching its 29th anniversary. During this time, Mauna Loa has slowly inflated following its most recent eruption in 1984. This is Mauna Loa's longest inter-eruptive interval observed in HVO's 100 years of operation. When will the next eruption of Mauna Loa take place? Is the next eruption of Mauna Loa tied to the current activity at Kilauea? Historically, eruptive periods at Kilauea and Mauna Loa volcanoes appear to be inversely correlated. In the past, when Mauna Loa was exceptionally active, Kilauea Volcano was in repose, recovery, or in sustained lava lake activity. Swanson and co-workers (this meeting) have noted that explosive activity on Kilauea, albeit sporadic, was interspersed between episodes of effusive activity. Specifically, Swanson and co-workers note as explosive the time periods between 300 B.C.E.-1000 C.E and 1500-1800 C.E. They also point to evidence for low magma supply to Kilauea during these periods and few flank eruptions. During the former explosive period, Mauna Loa was exceedingly active, covering approximately 37% of its surface or 1882 km2, an area larger than Kilauea. This period is also marked by summit activity at Mauna Loa sustained for 300 years. In the 1500-1800 C.E. period, Mauna Loa was conspicuously active with 29 eruptions covering an area of 446 km2. In the late 19th and early 20th century, Kilauea was dominated by nearly continuous lava-lake activity. Meanwhile Mauna Loa was frequently active from 1843 C.E. to 1919 C.E., with 24 eruptions for an average repose time of 3.5 years. I propose that eruptive activity at one volcano may affect eruptions at the other, due to factors that impact magma supply, volcanic plumbing, and flank motion. This hypothesis is predicated on the notion that when the rift zones of Kilauea, and in turn its mobile south flank, are active, Mauna Loa's tendency to erupt is diminished. Kilauea's rift zones help drive the south flank seaward, in turn, as Mauna

  19. 1996 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Neal, Christina A.; McGimsey, Robert G.

    1997-01-01

    During 1996, the Alaska Volcano Observatory (AVO) responded to eruptive activity, anomalous seismicity, or suspected volcanic activity at 10 of the approximately 40 active volcanic centers in the state of Alaska. As part of a formal role in KVERT (the Kamchatkan Volcano Eruption Response Team), AVO staff also disseminated information about eruptions and other volcanic unrest at six volcanic centers on the Kamchatka Peninsula and in the Kurile Islands, Russia.

  20. Results of geothermal gradient core hole TCB-1, Tecuamburro volcano geothermal site, Guatemala, Central America

    SciTech Connect

    Adams, A.I.; Chipera, S.; Counce, D.; Gardner, J.; Goff, S.; Goff, F.; Heiken, G.; Laughlin, A.W.; Musgrave, J.; Trujillo, P.E. Jr. ); Aycinena, S.; Martinelli, L. ); Castaneda, O.; Revolorio, M.; Roldan, A. . Inst. Nacional de Electrificacion); D

    1992-02-01

    Results of geological, volcanological, hydrogeochemical, and geophysical field studies conducted in 1988 and 1989 at the Tecuamburro volcano geothermal site in Guatemala indicated that there is a substantial shallow heat source beneath the area of youngest volcanism. To obtain information on subsurface temperatures and temperature gradients, stratigraphy, hydrothermal alteration, fracturing, and possible inflows of hydrothermal fluids, a geothermal gradient core hole (TCB-1) was drilled to 808 m low on the northern flank of the Tecuamburro volcano Complex, 300 km south of a 300-m-diameter phreatic crater, Laguna Ixpaco, dated at 2,910 years. Gases from acid-sulfate springs near Laguna Ixpaco consistently yield maximum estimated subsurface temperatures of 250--300{degrees}C. The temperature versus depth curve from TCB-1 does not show isothermal conditions and the calculated thermal gradients from 500--800 m is 230{degrees}C/km. Bottom hole temperature is 238{degrees}C. Calculated heat flow values are nearly 9 heat flow units (HFU). The integration of results from the TCB-1 gradient core hole with results from field studies provides strong evidence that the Tecuamburro area holds great promise for containing a commercial geothermal resource.

  1. Geothermal activity and energy of the Yakedake volcano, Gifu-Nagano, Japan

    SciTech Connect

    Iriyama, Jun

    1996-12-31

    The temperature of the most active solfatara in the summit crater of the Yakedake volcano (altitude 2,455 m Gifu-Nagano, Japan) was 92.2 and 129.4{degrees}C in September 1995 and in October 1994, respectively. The temperature of solfatara in the northern summit dome at an altitude of 2,240 to 2,270 m ranged from 68.2 to 92.5{degrees}C in September 1995. The water sample from a crater pond, Shoga-ike, located on the summit, showed a pH and electrical conductivity of 4.38 and 42.2 {mu}S/cm in October 1991, 4.35 and 42.4 {mu}S/cm in September 1992, 4.11 and 76.6 {mu}S/cm in October 1994, and 4.30 and 45.1 {mu}S/cm in September 1995, respectively. In 1960, the water sample from the same pond showed the pH and electrical conductivity of 3.7 and 80.8 {mu}S/cm, respectively. Although the values of pH and electrical conductivity in 1994 approached to the values at the volcano`s pre-eruption in 1960, the eruption in the summit dome did not occur in 1995. However, a large steam explosion occurred in the Nakanoyu area of the southeastern Mountainside of the volcano. The geothermal energy within the summit dome at an altitude of 2,050 to 2,455 m of the Yakedake volcano is calculated, using new data, to be about 4.8 x 10{sup 17} J, which represents a thermal power output of 5.1 x 10{sup 2} MW{sub th} averaged over 30 yrs.

  2. Evolution of Deformation Studies on Active Hawaiian Volcanoes

    NASA Astrophysics Data System (ADS)

    Decker, R.; Okamura, A.

    2004-12-01

    Summarizing 1600 years of observations and interpretations into a brief presentation forces some difficult choices on highlighting the following techniques that are presented chronologically: Visual Observations, 400 AD to present: Missionary William Ellis' Hawaiian Guides told him that Kilauea "had been burning from time immemorial, or, to use their own words, `mai ka po mai', from chaos till now...that in earlier ages it used to boil up, overflow its banks, and inundate the adjacent country...and on occasions they supposed Pele went by a road under ground from her house in the crater to the shore". Observations of the nearly-continuous lava lake in Kilauea Caldera from 1823 until 1924 established that its surface level fluctuated from about 700 to 1100 m above sea level in 10 up-and-down episodes. Tilt Measurements, 1914 to present: Horizontal-seismometer drift and water-tube tiltmeters show that the range of long-term, ground-surface tilt radial to Halemaumau Crater exceeds 500 microradians. Triangulation and Leveling, 1920: R. M. Wilson measured deformation changes related to major Kilauea summit subsidence in 1924. The caldera area around Halemaumau subsided concentrically as much as 4 m relative to the Volcano House benchmark, and triangulation points moved toward Halemaumau by as much as 1.6 m in the caldera area. K. Mogi in 1958 modeled Kilauea leveling data and inferred 3-4 km-deep magma reservoirs. Gravity Measurements, 1959 to present: Changes were first measured during Kilauea summit subsidence related to the lower-east-rift Kapoho eruption. Surveys made before and after the 1975 M7.2 Kalapana Earthquake show that gravity changes are not a simple proxy for elevation changes. Electronic Distance Measurements (EDM), 1964 to present: D. A. Swanson, W. A. Duffield, and R. S. Fiske use EDM for trilateration proving movement of the south flank of Kilauea toward the sea. EDM show displacements as large as 8.7 m of Kilauea's south flank toward the sea related

  3. The 1997 and 2001 lahars of Popocatépetl volcano (Central Mexico): textural and sedimentological constraints on their origin and hazards

    NASA Astrophysics Data System (ADS)

    Capra, L.; Poblete, M. A.; Alvarado, R.

    2004-03-01

    Popocatépetl volcano is the most active volcano in central Mexico, and represents a high risk for more than 40 million people, including Mexico City. In 1994, volcanic activity at Popocatépetl renewed with the formation of ash-rich plumes up to 7 km high. In April 1996, lava emissions filled the crater and were accompanied by a series of explosions that produced eruptive columns up to 8 km high. Associated with explosive events in 1997 and 2001, two major lahars events occurred, leaving debris flow deposits along Huiloac Gorge for as far as 15 km, to the town of Santiago Xalitzinta. The 1997 debris flow deposit originated after a prolonged emission of ash which caused glacier melt and a rapid release of water (1×10 7 m 3). The amount of melting water was sufficient to gradually erode the river bed causing a flood that gradually transformed from a debris flow to a hyperconcentrated flow. In contrast, the 2001 debris flow that originated from a post-depositional remobilization of a pumice flow deposit, did not experience any flow transformation and carried 25% water at maximum. The different behavior of these two lahars has important hazard implications. Both lahars reached Xalitzintla town, but at that point, the 1997 lahar had already transformed into a sediment-loaded stream flow. The 2001 lahar, by contrast, maintained the characteristics of a debris flow, being more competent, and with greater destructive power. What happened with these lahars demonstrates how important it is to take into consideration secondary volcanic phenomena. Even though they were not large flows, they were capable of threatening populated areas, even during periods of volcanic quiescence or reduced magmatic activity.

  4. Diversity and activity of benthic microbial communities at the North Alex mud volcano, Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Makarow, Dorothee; Feseker, Tomas; Schmitz, Ruth; Treude, Tina

    2010-05-01

    North Alex mud volcano, located on the upper slope of the western Nile deep-sea fan, is characterized by an active seepage center transporting pore fluids, hydrocarbons and gases from deep subsurface sources to the sediment-water interface. Surface sediments feature steep temperature gradient of 8.5°C m-1. We sampled the top 40 cm of the sediments at different locations between the center and rim of the mud volcano to study the diversity, activity, and physiological characteristics of benthic microorganisms. The sediments revealed the activity of anaerobic oxidation of methane coupled to sulfate reduction with a mesophilic temperature optimum. Organisms involved in the process include consortia of methanotrophic archaea (ANME-2 group) and an unknown bacterial partner. Besides methanotrophic organisms the sediments harbored a variety of other bacterial and archaeal groups - including potentially thermophilic bacteria that could be involved in sulfur cycling. This poster presentation will provide an overview of microbial activities and community compositions of North Alex mud volcano sediments.

  5. Analysis of the seismicity activity of the volcano Ceboruco, Nayarit, Mexico

    NASA Astrophysics Data System (ADS)

    Rodriguez-Ayala, N. A.; Nunez-Cornu, F. J.; Escudero, C. R.; Zamora-Camacho, A.; Gomez, A.

    2014-12-01

    The Ceboruco is a stratovolcano is located in the state of Nayarit,Mexico (104 ° 30'31 .25 "W, 21 ° 7'28 .35" N, 2280msnm). This is an volcano active, as part of the Trans-Mexican Volcanic Belt, Nelson (1986) reports that it has had activity during the last 1000 years has averaged eruptions every 125 years or so, having last erupted in 1870, currently has fumarolic activity. In the past 20 years there has been an increase in the population and socio-economic activities around the volcano (Suárez Plascencia, 2013); which reason the Ceboruco study has become a necessity in several ways. Recent investigations of seismicity (Rodríguez Uribe et al., 2013) have classified the earthquakes in four families Ceboruco considering the waveform and spectral features. We present analysis included 57 days of seismicity from March to October 2012, in the period we located 97 events with arrivals of P and S waves clear, registered in at least three seasons, three components of the temporal network Ceboruco volcano.

  6. Chemical composition of soils in the areas of volcanic ashfalls around active volcanoes in Kamchatka

    NASA Astrophysics Data System (ADS)

    Zakharikhina, L. V.; Litvinenko, Yu. S.

    2016-03-01

    The geochemical features of volcanic soils (Andosols) in the northern soil province of Kamchatka are identified. The background regional concentrations ( Cb r ) of most of chemical elements in the studied soils are lower than their average concentrations in soils of the world and in the European volcanic soils. Only Na, Ca, and Mg are present in elevated concentrations in all the studied soils in the north of Kamchatka. Regional background concentrations of elements are exceeded by 1.6 times in the area of active ashfalls of the Tolbachik volcano and by 1.3 times in the area of active ashfalls of the Shiveluch volcano. The concentrations of mobile forms of elements in these areas exceed their regional background concentrations by 2.1 and 2.6 times, respectively.

  7. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

    PubMed

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

  8. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

    NASA Astrophysics Data System (ADS)

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-02-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

  9. Long-term explosive degassing and debris flow activity at West Mata submarine volcano

    NASA Astrophysics Data System (ADS)

    Dziak, R. P.; Bohnenstiehl, D. R.; Baker, E. T.; Matsumoto, H.; Caplan-Auerbach, J.; Embley, R. W.; Merle, S. G.; Walker, S. L.; Lau, T.-K.; Chadwick, W. W.

    2015-03-01

    West Mata is a 1200 m deep submarine volcano where explosive boninite eruptions were observed in 2009. The acoustic signatures from the volcano's summit eruptive vents Hades and Prometheus were recorded with an in situ (~25 m range) hydrophone during ROV dives in May 2009 and with local (~5 km range) moored hydrophones between December 2009 and August 2011. The sensors recorded low frequency (1-40 Hz), short duration explosions consistent with magma bubble bursts from Hades, and broadband, 1-5 min duration signals associated with episodes of fragmentation degassing from Prometheus. Long-term eruptive degassing signals, recorded through May 2010, preceded a several month period of declining activity. Degassing episodes were not recorded acoustically after early 2011, although quieter effusive eruption activity may have continued. Synchronous optical measurements of turbidity made between December 2009 and April 2010 indicate that turbidity maxima resulted from occasional south flank slope failures triggered by the collapse of accumulated debris during eruption intervals.

  10. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

    PubMed Central

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

  11. The unrest of the San Miguel volcano (El Salvador, Central America): installation of the monitoring network and observed volcano-tectonic ground deformation

    NASA Astrophysics Data System (ADS)

    Bonforte, Alessandro; Hernandez, Douglas Antonio; Gutiérrez, Eduardo; Handal, Louis; Polío, Cecilia; Rapisarda, Salvatore; Scarlato, Piergiorgio

    2016-08-01

    On 29 December 2013, the Chaparrastique volcano in El Salvador, close to the town of San Miguel, erupted suddenly with explosive force, forming a column more than 9 km high and projecting ballistic projectiles as far as 3 km away. Pyroclastic density currents flowed to the north-northwest side of the volcano, while tephras were dispersed northwest and north-northeast. This sudden eruption prompted the local Ministry of Environment to request cooperation with Italian scientists in order to improve the monitoring of the volcano during this unrest. A joint force, made up of an Italian team from the Istituto Nazionale di Geofisica e Vulcanologia and a local team from the Ministerio de Medio Ambiente y Recursos Naturales, was organized to enhance the volcanological, geophysical and geochemical monitoring system to study the evolution of the phenomenon during the crisis. The joint team quickly installed a multiparametric mobile network comprising seismic, geodetic and geochemical sensors (designed to cover all the volcano flanks from the lowest to the highest possible altitudes) and a thermal camera. To simplify the logistics for a rapid installation and for security reasons, some sensors were colocated into multiparametric stations. Here, we describe the prompt design and installation of the geodetic monitoring network, the processing and results. The installation of a new ground deformation network can be considered an important result by itself, while the detection of some crucial deforming areas is very significant information, useful for dealing with future threats and for further studies on this poorly monitored volcano.

  12. Mud volcanoes of the Orinoco Delta, Eastern Venezuela

    USGS Publications Warehouse

    Aslan, A.; Warne, A.G.; White, W.A.; Guevara, E.H.; Smyth, R.C.; Raney, J.A.; Gibeaut, J.C.

    2001-01-01

    Mud volcanoes along the northwest margin of the Orinoco Delta are part of a regional belt of soft sediment deformation and diapirism that formed in response to rapid foredeep sedimentation and subsequent tectonic compression along the Caribbean-South American plate boundary. Field studies of five mud volcanoes show that such structures consist of a central mound covered by active and inactive vents. Inactive vents and mud flows are densely vegetated, whereas active vents are sparsely vegetated. Four out of the five mud volcanoes studied are currently active. Orinoco mud flows consist of mud and clayey silt matrix surrounding lithic clasts of varying composition. Preliminary analysis suggests that the mud volcano sediment is derived from underlying Miocene and Pliocene strata. Hydrocarbon seeps are associated with several of the active mud volcanoes. Orinoco mud volcanoes overlie the crest of a mud-diapir-cored anticline located along the axis of the Eastern Venezuelan Basin. Faulting along the flank of the Pedernales mud volcano suggests that fluidized sediment and hydrocarbons migrate to the surface along faults produced by tensional stresses along the crest of the anticline. Orinoco mud volcanoes highlight the proximity of this major delta to an active plate margin and the importance of tectonic influences on its development. Evaluation of the Orinoco Delta mud volcanoes and those elsewhere indicates that these features are important indicators of compressional tectonism along deformation fronts of plate margins. ?? 2001 Elsevier Science B.V. All rights reserved.

  13. Density Imaging of Puy de Dôme Volcano with Atmospheric Muons in French Massif Central as a Case Study for Volcano Muography

    NASA Astrophysics Data System (ADS)

    Carloganu, Cristina; Le Ménédeu, Eve

    2016-04-01

    High energy atmospheric muons have high penetration power that renders them appropriate for geophysical studies. Provided the topography is known, the measurement of the muon flux transmittance leads in an univoque way to 2D density mapping (so called radiographic images) revealing spatial and possibly also temporal variations. Obviously, several radiographic images could be combined into 3D tomographies, though the inverse 3D problem is generally ill-posed. The muography has a high potential for imaging remotely (from kilometers away) and with high resolution (better than 100 mrad2) volcanoes. The experimental and methodological task is however not straightforward since atmospheric muons have non trivial spectra that fall rapidly with muon energy. As shown in [Ambrosino 2015] successfully imaging km-scale volcanoes remotely requires state-of-the art, high-resolution and large-scale muon detectors. This contribution presents the geophysical motivation for muon imaging as well as the first quantitative density radiographies of Puy de Dôme volcano obtained by the TOMUVOL collaboration using a highly segmented muon telescope based on Glass Resistive Plate Chambers. In parallel with the muographic studies, the volcano was imaged through standard geophysical methods (gravimetry, electrical resistivity) [Portal 2013] allowing in depth comparisons of the different methods. Ambrosino, F., et al. (2015), Joint measurement of the atmospheric muon flux through the Puy de Dôme volcano with plastic scintillators and Resistive Plate Chambers detectors, J. Geophys. Res. Solid Earth, 120, doi:10.1002/2015JB011969 A. Portal et al (2013) , "Inner structure of the Puy de Dme volcano: cross-comparison of geophysical models (ERT, gravimetry, muon imaging)", Geosci. Instrum. Method. Data Syst., 2, 47-54, 2013

  14. Cellular immune responses and phagocytic activity of fishes exposed to pollution of volcano mud.

    PubMed

    Risjani, Yenny; Yunianta; Couteau, Jerome; Minier, Christophe

    2014-05-01

    Since May 29, 2006, a mud volcano in the Brantas Delta of the Sidoarjo district has emitted mud that has inundated nearby villages. Pollution in this area has been implicated in detrimental effects on fish health. In fishes, leukocyte and phagocytic cells play a vital role in body defenses. We report for the first time the effect of "LUSI" volcano mud on the immune systems of fish in the Brantas Delta. The aim of this study was to find biomarkers to allow the evaluation of the effects of volcanic mud and anthropogenic pollution on fish health in the Brantas Delta. The study took places at the Brantas Delta, which was polluted by volcano mud, and at reference sites in Karangkates and Pasuruan. Leukocyte numbers were determined using a Neubauer hemocytometer and a light microscope. Differential leukocyte counts were determined using blood smears stained with May Grunwald-Giemsa, providing neutrophil, lymphocyte and monocyte counts. Macrophages were taken from fish kidney, and their phagocytic activity was measured. In vitro analyses revealed that leukocyte and differential leukocyte counts (DLC) were higher in Channa striata and Chanos chanos caught from the polluted area. Macrophage numbers were higher in Oreochromis mossambicus than in the other species, indicating that this species is more sensitive to pollution. In areas close to volcanic mud eruption, all specimens had lower phagocytic activity. Our results show that immune cells were changed and phagocytic activity was reduced in the polluted area indicating cytotoxicity and alteration of the innate immune system in fishes exposed to LUSI volcano mud and anthropogenic pollution. PMID:24631200

  15. Autonomous thermal camera system for monitoring the active lava lake at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Peters, N.; Oppenheimer, C.; Kyle, P.

    2014-02-01

    In December 2012, the Mount Erebus Volcano Observatory installed a thermal infrared camera system to monitor the volcano's active lava lake. The new system is designed to be autonomous, and capable of capturing images of the lava lake continuously throughout the year. This represents a significant improvement over previous systems which required the frequent attention of observatory researchers and could therefore only be operated during a few weeks of the annual field campaigns. The extreme environmental conditions at the summit of Erebus pose significant challenges for continuous monitoring equipment, and a custom-made system was the only viable solution. Here we describe the hardware and software of the new system in detail and report on a publicly available online repository where data will be archived. Aspects of the technical solutions we had to find in order to overcome the challenges of automating this equipment may be relevant in other environmental science domains where remote instrument operation is involved.

  16. Autonomous thermal camera system for monitoring the active lava lake at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Peters, N.; Oppenheimer, C.; Kyle, P.

    2013-10-01

    In December 2012, the Mount Erebus Volcano Observatory installed a thermal infrared camera system to monitor the volcano's active lava lake. The new system is designed to be autonomous, and capable of capturing images of the lava lake continuously throughout the year. This represents a significant improvement over previous systems which required the frequent attention of observatory researchers and could therefore only be operated during a few weeks of the annual field campaigns. The extreme environmental conditions at the summit of Erebus pose significant challenges for continuous monitoring equipment, and a custom made system was the only viable solution. Here we describe the hardware and software of the new system in detail and report on a publicly-available online repository where data will be archived. Aspects of the technical solutions we had to find in order to overcome the challenges of automating this equipment may be relevant in other environmental science domains where remote instrument operation is involved.

  17. Lifespans of Cascade Arc volcanoes

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.

    2015-12-01

    Compiled argon ages reveal inception, eruptive episodes, ages, and durations of Cascade stratovolcanoes and their ancestral predecessors. Geologic mapping and geochronology show that most Cascade volcanoes grew episodically on multiple scales with periods of elevated behavior lasting hundreds of years to ca. 100 kyr. Notable examples include the paleomag-constrained, few-hundred-year-long building of the entire 15-20 km3 Shastina edifice at Mt. Shasta, the 100 kyr-long episode that produced half of Mt. Rainier's output, and the 30 kyr-long episode responsible for all of South and Middle Sister. Despite significant differences in timing and rates of construction, total durations of active and ancestral volcanoes at discrete central-vent locations are similar. Glacier Peak, Mt. Rainier, Mt. Adams, Mt. Hood, and Mt. Mazama all have inception ages of 400-600 ka. Mt. St. Helens, Mt. Jefferson, Newberry Volcano, Mt. Shasta and Lassen Domefield have more recent inception ages of 200-300 ka. Only the Sisters cluster and Mt. Baker have established eruptive histories spanning less than 50 kyr. Ancestral volcanoes centered 5-20 km from active stratocones appear to have similar total durations (200-600 kyr), but are less well exposed and dated. The underlying mechanisms governing volcano lifecycles are cryptic, presumably involving tectonic and plumbing changes and perhaps circulation cycles in the mantle wedge, but are remarkably consistent along the arc.

  18. Alaska Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Murray, Tom; Read, Cyrus

    2008-01-01

    Steam plume from the 2006 eruption of Augustine volcano in Cook Inlet, Alaska. Explosive ash-producing eruptions from Alaska's 40+ historically active volcanoes pose hazards to aviation, including commercial aircraft flying the busy North Pacific routes between North America and Asia. The Alaska Volcano Observatory (AVO) monitors these volcanoes to provide forecasts of eruptive activity. AVO is a joint program of the U.S. Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Augustine volcano and AVO at http://www.avo.alaska.edu.

  19. Estimating eruption temperature from thermal emission spectra of lava fountain activity in the Erta'Ale (Ethiopia) volcano lava lake: Implications for observing Io's volcanoes

    USGS Publications Warehouse

    Davies, Ashley G.; Keszthelyi, Laszlo P.; McEwen, Alfred S.

    2011-01-01

    We have analysed high-spatial-resolution and high-temporal-resolution temperature measurements of the active lava lake at Erta'Ale volcano, Ethiopia, to derive requirements for measuring eruption temperatures at Io's volcanoes. Lava lakes are particularly attractive targets because they are persistent in activity and large, often with ongoing lava fountain activity that exposes lava at near-eruption temperature. Using infrared thermography, we find that extracting useful temperature estimates from remote-sensing data requires (a) high spatial resolution to isolate lava fountains from adjacent cooler lava and (b) rapid acquisition of multi-color data. Because existing spacecraft data of Io's volcanoes do not meet these criteria, it is particularly important to design future instruments so that they will be able to collect such data. Near-simultaneous data at more than two relatively short wavelengths (shorter than 1 μm) are needed to constrain eruption temperatures. Resolving parts of the lava lake or fountains that are near the eruption temperature is also essential, and we provide a rough estimate of the required image scale.

  20. Estimating eruption temperature from thermal emission spectra of lava fountain activity in the Erta'Ale (Ethiopia) volcano lava lake: Implications for observing Io's volcanoes

    USGS Publications Warehouse

    Davies, A.G.; Keszthelyi, L.; McEwen, A.S.

    2011-01-01

    We have analysed high-spatial-resolution and high-temporal-resolution temperature measurements of the active lava lake at Erta'Ale volcano, Ethiopia, to derive requirements for measuring eruption temperatures at Io's volcanoes. Lava lakes are particularly attractive targets because they are persistent in activity and large, often with ongoing lava fountain activity that exposes lava at near-eruption temperature. Using infrared thermography, we find that extracting useful temperature estimates from remote-sensing data requires (a) high spatial resolution to isolate lava fountains from adjacent cooler lava and (b) rapid acquisition of multi-color data. Because existing spacecraft data of Io's volcanoes do not meet these criteria, it is particularly important to design future instruments so that they will be able to collect such data. Near-simultaneous data at more than two relatively short wavelengths (shorter than 1 ??m) are needed to constrain eruption temperatures. Resolving parts of the lava lake or fountains that are near the eruption temperature is also essential, and we provide a rough estimate of the required image scale. ?? 2011 by the American Geophysical Union.

  1. Estimating eruption temperature from thermal emission spectra of lava fountain activity in the Erta'Ale (Ethiopia) volcano lava lake: Implications for observing Io's volcanoes

    NASA Astrophysics Data System (ADS)

    Davies, Ashley Gerard; Keszthelyi, Laszlo; McEwen, Alfred S.

    2011-11-01

    We have analysed high-spatial-resolution and high-temporal-resolution temperature measurements of the active lava lake at Erta'Ale volcano, Ethiopia, to derive requirements for measuring eruption temperatures at Io's volcanoes. Lava lakes are particularly attractive targets because they are persistent in activity and large, often with ongoing lava fountain activity that exposes lava at near-eruption temperature. Using infrared thermography, we find that extracting useful temperature estimates from remote-sensing data requires (a) high spatial resolution to isolate lava fountains from adjacent cooler lava and (b) rapid acquisition of multi-color data. Because existing spacecraft data of Io's volcanoes do not meet these criteria, it is particularly important to design future instruments so that they will be able to collect such data. Near-simultaneous data at more than two relatively short wavelengths (shorter than 1 μm) are needed to constrain eruption temperatures. Resolving parts of the lava lake or fountains that are near the eruption temperature is also essential, and we provide a rough estimate of the required image scale.

  2. Base surge deposits, eruption history, and depositional processes of a wet phreatomagmatic volcano in Central Anatolia (Cora Maar)

    NASA Astrophysics Data System (ADS)

    Gençalioğlu-Kuşcu, Gonca; Atilla, Cüneyt; Cas, Ray A. F.; Kuşcu, İlkay

    2007-01-01

    Cora Maar is a Quaternary volcano located to the 20 km northwest of Mount Erciyes, the largest of the 19 polygenetic volcanic complexes of the Cappadocian Volcanic Province in central Anatolia. Cora Maar is a typical example of a maar-diatreme volcano with a nearly circular crater with a mean diameter of c.1.2 km, and a well-bedded base surge-dominated maar rim tephra sequence up to 40 m in thickness. Having a diameter/depth ratio ( D/ d) of 12, Cora is a relatively "mature" maar compared to recent maar craters in the world. Cora crater is excavated within the andesitic lava flows of Quaternary age. The tephra sequence is not indurated, and consists of juvenile clasts up to 70 cm, non-juvenile clasts up to 130 cm, accretionary lapilli up to 1.2 cm in diameter, and ash to lapilli-sized tephra. Base surge layers display well-developed antidune structures indicating the direction of the transport. Both progressive and regressive dune structures are present within the tephra sequence. Wavelength values increase with increasing wave height, and with large wavelength and height values. Cora tephra display similarities to Taal and Laacher See base surge deposits. Impact sags and small channel structures are also common. Lateral and vertical facies changes are observed for the dune bedded and planar bedsets. According to granulometric analyses, Cora Maar tephra samples display a bimodal distribution with a wide range of Md φ values, characteristic for the surge deposits. Very poorly sorted, bimodal ash deposits generally vary from coarse tail to fine tail grading depending on the grain size distribution while very poorly sorted lapilli and block-rich deposits display a positive skewness due to fine tail grading.

  3. Zonation of North Alex Mud Volcano Highlighted by 3-D Active and Passive Seismic Data

    NASA Astrophysics Data System (ADS)

    Bialas, J.; Lefeldt, M. R.; Klaeschen, D.; Papenberg, C. A.; Brueckmann, W.

    2010-12-01

    The West Nile Delta forms part of the source of the large turbiditic Nile Deep Sea Fan. Since the late Miocene sediments have formed an up to 10 km thick pile, which includes about 1 - 3 km of Messinian evaporates. The sediment load of the overburden implies strong overpressures and salt-related tectonic deformation. Both are favourable for fluid migration towards the seafloor guided by the fractured margin. The western deltaic system, Rosetta branch, has formed an 80 km wide continental shelf. Here at 700 m water depth the mud volcano North Alex (NA) developed his circular bathymetric feature, which proved to be an active gas and mud-expelling structure. A 3-D high-resolution multichannel seismic survey (IFM-GEOMAR P-Cable system) was completed across the mud volcano. 3-D time migration provided a 3-D data cube with a 6.25 m grid. Vertical seismic sections did reveal a large set of faults located within the main mud volcano as well as surrounding the structure. Internal faults are mainly related to episodic mud expulsion processes and continuous gas and fluid production. Deep cutting external faults surround the structure in a half circle shape. Horizontal amplitude maps (time slices) of indicate recent activity of these faults even up to the seafloor. High gas saturation of the sediments is indicated by inverted reflection events. In the centre the gas front cuts into the seafloor reflection while it dips down with increasing radius. Only with the small grid resolution inward dipping reflections become visible, which form an upward opened concave reflector plane underlying the top gas front. The interpretation assumes an oval lens shaped body (conduit) saturated with gas at the top of the mud volcano. It provides the upper termination of the mud chimney. This separation is further supported by passive seismic observations. Distant earthquakes can stimulate long-period harmonic oscillations in mud volcanoes. Such oscillations are detectable with three

  4. Catalogue of Icelandic volcanoes

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Vogfjörd, Kristin; Tumi Gudmundsson, Magnus; Jonsson, Trausti; Oddsson, Björn; Reynisson, Vidir; Barsotti, Sara; Karlsdottir, Sigrun

    2015-04-01

    Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene. In the last 100 years, over 30 eruptions have occurred displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and their distribution. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in scientific papers and other publications. In 2010, the International Civil Aviation Organisation funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland (commenced in 2012), and the EU FP7 project FUTUREVOLC (2012-2016), establishing an Icelandic volcano Supersite. The Catalogue is a collaborative effort between the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Icelandic Civil Protection, with contributions from a large number of specialists in Iceland and elsewhere. The catalogue is scheduled for opening in the first half of 2015 and once completed, it will be an official publication intended to serve as an accurate and up to date source of information about active volcanoes in Iceland and their characteristics. The Catalogue is an open web resource in English and is composed of individual chapters on each of the volcanic systems. The chapters include information on the geology and structure of the volcano; the eruption history, pattern and products; the known precursory signals

  5. Explosion Energy of the 2004 Eruption of the Asama Volcano, Central Japan: Inference From Ionospheric Disturbances Observed by a Dense GPS Array

    NASA Astrophysics Data System (ADS)

    Heki, K.

    2006-12-01

    Ionospheric Total Electron Content (TEC) can be easily measured as the phase differences of the L1 and L2 band carrier waves from Global Positioning System (GPS) satellites. Ionospheric disturbances measured as TEC changes have been contributing to not only solar-terrestrial studies but also solid earth geophysics, e.g. constraining the source process of the 2004 Sumatra Earthquake (Heki et al., JGR, 2006). Here I present a new application of GPS-TEC, i.e. estimation of the explosion energy of a volcanic eruption (Heki, GRL, 2006). The Asama Volcano, Central Japan, started eruptive activity at 11:02 UT on September 1, 2004, with a vulcanian explosion associated with strong airwaves. The Japanese dense GPS array GEONET recorded ionospheric disturbances as N-shaped changes in TEC approximately 12 minutes after the eruption. The disturbance had a period of 1.25 minutes and propagated as fast as about 1.1 km/s, suggesting its origin as the acoustic wave generated by the explosion. By comparing the disturbance amplitudes with those by a surface mine blast with a known energy (Calais et al., GJI, 1998), the overall Asama explosion energy is inferred to be equivalent to 1.2e14 Joule, about one third of the energy reported for the 1938 eruption (Minakami, BERI, 1942). Energy of the airwave can be estimated following Johnson (JVGR, 2003), assuming that the disturbance is a part of the spherical wave propagated from the volcano. We thus obtained the value 9.0e6 Joule, a typical value of airwave energies associated with volcanic eruptions. This new technique would complement past methods based on observations of mass deficits, near-field measurements of airwaves, etc, and may contribute to mitigation of volcanic hazards.

  6. Biological Studies on a Live Volcano.

    ERIC Educational Resources Information Center

    Zipko, Stephen J.

    1992-01-01

    Describes scientific research on an Earthwatch expedition to study Arenal, one of the world's most active volcanoes, in north central Costa Rica. The purpose of the two-week project was to monitor and understand the past and ongoing development of a small, geologically young, highly active stratovolcano in a tropical, high-rainfall environment.…

  7. 1997 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Wallace, Kristi L.

    1999-01-01

    The Alaska Volcano Observatory (AVO) monitors over 40 historically active volcanoes along the Aleutian Arc. Twenty are seismically monitored and for the rest, the AVO monitoring program relies mainly on pilot reports, observations of local residents and ship crews, and daily analysis of satellite images. In 1997, AVO responded to eruptive activity or suspect volcanic activity at 11 volcanic centers: Wrangell, Sanford, Shrub mud volcano, Iliamna, the Katmai group (Martin, Mageik, Snowy, and Kukak volcanoes), Chiginagak, Pavlof, Shishaldin, Okmok, Cleveland, and Amukta. Of these, AVO has real-time, continuously recording seismic networks at Iliamna, the Katmai group, and Pavlof. The phrase “suspect volcanic activity” (SVA), used to characterize several responses, is an eruption report or report of unusual activity that is subsequently determined to be normal or enhanced fumarolic activity, weather-related phenomena, or a non-volcanic event. In addition to responding to eruptive activity at Alaska volcanoes, AVO also disseminated information for the Kamchatkan Volcanic Eruption Response Team (KVERT) about the 1997 activity of 5 Russian volcanoes--Sheveluch, Klyuchevskoy, Bezymianny, Karymsky, and Alaid (SVA). This report summarizes volcanic activity and SVA in Alaska during 1997 and the AVO response, as well as information on the reported activity at the Russian volcanoes. Only those reports or inquiries that resulted in a “significant” investment of staff time and energy (here defined as several hours or more for reaction, tracking, and follow-up) are included. AVO typically receives dozens of reports throughout the year of steaming, unusual cloud sightings, or eruption rumors. Most of these are resolved quickly and are not tabulated here as part of the 1997 response record.

  8. Carbon-14 ages of the past 20 ka of eruptive activity of Teide volcano, Canary Islands

    NASA Astrophysics Data System (ADS)

    Carracedo, J. C.; Guillou, H.; Paterne, M.; Pérez Torrado, F. J.; Paris, R.; Badiola, E. R.

    2003-04-01

    Teide volcano, the highest volcano on earth (3718 m a.s.l., >7 Km high) after Mauna Loa and Mauna Kea in the Hawaiian Islands, forms a volcanic complex in the centre of the Island of Tenerife. Its most recent eruptive activity (last 20 Ka) is associated with the very active NW branch of the 120º triple rift system of the island. Most of the eruptions of Tenerife during the past 20 ka have occurred along this volcanic feature, frequently in the production of extensive mafic and felsic lava flows, many of which reached the coast, crossing what is now one of the most densely populated areas of Tenerife and of any oceanic island in the world. However, despite numerous previous studies, very important basic geological information is still lacking, in particular dating of these flows to construct a geochronological framework for the evolution of the Teide-NW rift system, and a scientifically based, much needed volcanic hazard assessment. New carbon-14 ages, obtained via coupled mass spectrometer, and others in process, provide important time constraints on the evolution of Teide's volcanic system, the frequency and distribution of its eruptions, and the associated volcanic hazards. Most of the eruptions are not related to the Teide stratovolcano, which apparently had only one eruption in the last 20 Ka about 1240 ± 60 years BP, but to the Pico Viejo volcano (17570 ± 150 years BP), flank parasitic vents (Mña. Abejera upper vent, 5170 ± 110 years BP; Mña. Abejera lower vent, 4790 ± 70 years BP; Mancha Ruana, 2420 ± 70 years BP; Mña. La Angostura, 2010 ± 60 years BP and Roques Blancos, 1790 ± 60 years BP) and the NW rift (Mña. Chío, 3620 ± 70 years BP). Although the volcanic activity during the past 20 ka included the involvement of at least 7 voluminous phonolitic flank vents in the northern, more unstable slopes of the Teide, it took place without any apparent response of the volcano; on the contrary, these eruptions seemed to progressively buttress and

  9. Geodetic Observations and Numerical Models of Magmatic Activity at Taal Volcano, Philippines

    NASA Astrophysics Data System (ADS)

    Hamburger, M. W.; Galgana, G. A.; Newman, A. V.; Solidum, R. U.; Bacolcol, T.

    2009-12-01

    We present modeling results based on geodetic observations at Taal Volcano, an active, tholeiitic volcano situated in southwestern Luzon, Philippines. The ~25 km2 multi-vent stratovolcano is located inside a 30-km wide caldera lake, situated within a volcanic region affected by transtensional tectonics. Continuous dual- and single-frequency (L1) GPS observations from 1998-2005 of sites situated around the volcano reveal deformation pulses averaging 3-9 months in length, with inflationary phases producing > 200 mm/yr of surface extension accompanied by 120 mm uplift (in 2000), and about 73 mm/yr extension with 50 mm uplift in early 2005. We use a two-step modeling procedure to seek the sources for this rapid volcanic deformation: first, we use analytical models to determine the Mogi (small spherical) source of deformation, using inversions at selected periods when there are significant inflationary/deflationary changes observed by surface deformation measurements. We determine the best-fit Mogi source to be near the center of Volcano Island, at ~5 km below the surface, similar to that determined for all of the major deformation events. Then, based on the best-fit source locations, axisymmetric finite element models are constructed to represent crustal geometry at the vicinity of Taal volcano. The continuous GPS time series is then used to constrain forward models by estimating the pressurization history at the source, represented by a 1-kilometer radius spherical reservoir with annuli of concentric shells (modeled initially as elastic, then viscoelastic), embedded within a multi-layered elastic lithosphere. The deformation estimates are then statistically compared, with the best-fit forward models showing active patterns of pressure variations. Results show that purely elastic approximation of the volcanic lithosphere produces significantly higher pressure (or volume) change estimates of magma chamber inflation/deflation, as compared to models incorporating a time

  10. PS-InSAR measurements at the most active volcanoes in Iceland: role of the GEO supersite initiative in deformation monitoring at Bárðarbunga, Askja, Hekla, Katla and Eyjafjallajökull volcanoes

    NASA Astrophysics Data System (ADS)

    Parks, Michelle; Dumont, Stéphanie; Drouin, Vincent; Sigmundsson, Freysteinn; Spaans, Karsten; Hooper, Andrew; Ófeigsson, Benedikt; Árnadóttir, Þóra; Hreinsdóttir, Sigrún; Michalczewska, Karolina; Hjaltadóttir, Sigurlaug; María Friðriksdóttir, Hildur; Rut Hjartardóttir, Ásta; Magnússon, Eyjólfur; Vogfjörd, Kristín; Jónsdóttir, Kristín; Hensch, Martin; Guðmundsson, Gunnar; Geirsson, Halldór; Sturkell, Erik

    2015-04-01

    deformation studies utilising data spanning this eruption, have provided insight into the shallow plumbing system, which may explain the large reduction in eruption repose interval following the 1970 eruption. InSAR and GPS observations at Katla volcano prior to 2010 suggest no magma induced deformation. However, deformation associated with a small flood at Mýrdalsjökull in July 2011, followed by an increase in micro-seismic earthquakes, could be interpreted in relation to magma movements. Post-eruption deformation observations reveal inflation at Eyjafjallajökull possibly related to the influx of new melt or readjustment of crustal stresses following the 2010 eruption. Continued deflation at Askja caldera since 1983 may have led to crustal weakening and the triggering of a mega rockslide and subsequent tsunami occurring on the 21 July 2014. Interferograms spanning the recent unrest and eruption within the Bárðarbunga volcanic system display both pre-eruptive and co-eruptive deformation associated with the initial dyke emplacement and ongoing magma withdrawal from beneath the Bárðarbunga central volcano. Continued high-resolution geodetic observations at these volcanoes are essential for assessing changes in their behaviour and the associated hazards. Rapid analysis of interferograms combined with GPS and earthquake seismicity measurements assists in tracking the evolution of magmatic activity during volcanic unrest/eruption, and may facilitate the assessment of associated hazards.

  11. Holocene eruptive activity of El Chichon volcano, Chiapas, Mexico

    NASA Astrophysics Data System (ADS)

    Tilling, R. I.; Rubin, M.; Sigurdsson, H.; Carey, S.; Duffield, W. A.; Rose, W. I.

    1984-05-01

    Geologic and radiometric-age data indicate that El Chichon was frequently and violently active during the Holocene, including eruptive episodes about 600, 1250, and 1700 years ago and several undated, older eruptions. These episodes, involving explosive eruptions of sulfur-rich magma and associated domegrowth processes, were apparently separated by intervals of approximately 350 to 650 years. Some of El Chichon's eruptions may correlate with unusual atmospheric phenomena around A.D. 1300 and possibly A.D. 623.

  12. Holocene eruptive activity of El Chichon volcano, Chiapas, Mexico

    NASA Technical Reports Server (NTRS)

    Tilling, R. I.; Rubin, M.; Sigurdsson, H.; Carey, S.; Duffield, W. A.; Rose, W. I.

    1984-01-01

    Geologic and radiometric-age data indicate that El Chichon was frequently and violently active during the Holocene, including eruptive episodes about 600, 1250, and 1700 years ago and several undated, older eruptions. These episodes, involving explosive eruptions of sulfur-rich magma and associated domegrowth processes, were apparently separated by intervals of approximately 350 to 650 years. Some of El Chichon's eruptions may correlate with unusual atmospheric phenomena around A.D. 1300 and possibly A.D. 623.

  13. Methanogenic diversity and activity in hypersaline sediments of the centre of the Napoli mud volcano, Eastern Mediterranean Sea.

    PubMed

    Lazar, Cassandre Sara; Parkes, R John; Cragg, Barry A; L'Haridon, Stéphane; Toffin, Laurent

    2011-08-01

    Submarine mud volcanoes are a significant source of methane to the atmosphere. The Napoli mud volcano, situated in the brine-impacted Olimpi Area of the Eastern Mediterranean Sea, emits mainly biogenic methane particularly at the centre of the mud volcano. Temperature gradients support the suggestion that Napoli is a cold mud volcano with moderate fluid flow rates. Biogeochemical and molecular genetic analyses were carried out to assess the methanogenic activity rates, pathways and diversity in the hypersaline sediments of the centre of the Napoli mud volcano. Methylotrophic methanogenesis was the only significant methanogenic pathway in the shallow sediments (0-40 cm) but was also measured throughout the sediment core, confirming that methylotrophic methanogens could be well adapted to hypersaline environments. Hydrogenotrophic methanogenesis was the dominant pathway below 50 cm; however, low rates of acetoclastic methanogenesis were also present, even in sediment layers with the highest salinity, showing that these methanogens can thrive in this extreme environment. PCR-DGGE and methyl coenzyme M reductase gene libraries detected sequences affiliated with anaerobic methanotrophs (mainly ANME-1) as well as Methanococcoides methanogens. Results show that the hypersaline conditions in the centre of the Napoli mud volcano influence active biogenic methane fluxes and methanogenic/methylotrophic diversity. PMID:21382146

  14. Volcano Observations Using an Unmanned Autonomous Helicopter : seismic and GPS observations near the active summit area of Sakurajima and Kirishima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ohminato, T.; Kaneko, T.; Koyama, T.; Watanabe, A.; Takeo, M.; Iguchi, M.; Honda, Y.

    2012-04-01

    Observations in the vicinity of summit area of active volcanoes are very important from various viewpoints such as understanding physical processes in the volcanic conduit. It is, however, highly difficult to install observation sensors near active vents because of the risk of sudden eruptions. We have been developing a safe volcano observation system based on an unmanned aerial vehicle (UAV). As an UAV, we adopted an unmanned autonomous helicopter manufactured by Yamaha-Motor Co., Ltd. We have also developed earthquake observation modules and GPS receiver modules that are exclusively designed for UAV installation at summit areas of active volcanoes. These modules are light weight, compact size, and solar powered. For data transmission, a commercial cellular-phone network is used. Our first application of the sensor installation by the UAV is Sakurajima, one of the most active volcanos in Japan. In November 2009, 2010, and 2011, we installed up to four seismic sensors within 2km from the active summit crater. In the 2010 and 2011 operations, we succeeded in pulling up and collecting the sensor modules by using the UAV. In the 2011 experiment, we installed two GPS receivers near the summit area of Sakurajima volcano. We also applied the UAV installation to another active volcano, Shinmoedake in Kirishima volcano group. Since the sub-plinian eruption in February 2011, entering the area 3km from the summit of Shinmoe-dake has been prohibited. In May and November 2011, we installed seismic sensors and GPS receivers in the off-limit zone. Although the ground coupling of the seismic modules is not perfect due to the way they are installed, the signal-to-noise ratio of the seismic signals recorded by these modules is fairly good. Despite the low antenna height of 50 cm from the ground surface, the location errors in horizontal and vertical GPS components are 1cm and 3cm, respectively. For seismic signals associated with eruptions at Sakurajima from November 2010 to

  15. Monitoring eruption activity from temporal stress changes at Mt. Ontake volcano, Japan

    NASA Astrophysics Data System (ADS)

    Terakawa, T.; Kato, A.; Yamanaka, Y.; Maeda, Y.; Horikawa, S.; Matsuhiro, K.; Okuda, T.

    2015-12-01

    On 27 September 2014, Mt. Ontake in Japan produced a phreatic (steam type) eruption with a Volcanic Explosivity Index value of 2 after being dormant for seven years. The local stress field around volcanoes is the superposition of the regional stress field and stress perturbations related to volcanic activity. Temporal stress changes over periods of weeks to months are generally attributed to volcanic processes. Here we show that monitoring temporal changes in the local stress field beneath Mt. Ontake, using focal mechanism solutions of volcano-tectonic (VT) earthquakes, is an effective tool for assessing the state of volcanic activity. We estimated focal mechanism solutions of 157 VT earthquakes beneath Mt. Ontake from August 2014 to March 2015, assuming that the source was double-couple. Pre-eruption seismicity was dominated by normal faulting with east-west tension, whereas most post-eruption events were reverse faulting with east-west compression. The misfit angle between observed slip vectors and those derived theoretically from the regional (i.e., background) stress pattern is used to evaluate the deviation of the local stress field, or the stress perturbation related to volcanic activity. The moving average of misfit angles tended to exceed 90° before the eruption, and showed a marked decrease immediately after the eruption. This indicates that during the precursory period the local stress field beneath Mt. Ontake was rotated by stress perturbations caused by the inflation of magmatic/hydrothermal fluids. Post-eruption events of reverse faulting acted to shrink the volcanic edifice after expulsion of volcanic ejecta, controlled by the regional stress field. The misfit angle is a good indicator of the state of volcanic activity. The monitoring method by using this indicator is applicable to other volcanoes and may contribute to the mitigation of volcanic hazards.

  16. The model of the Uzon-Geizernaya volcano-tectonic depression and Kikhpinych volcano, Kamchatka, from the joint analysis of microseismic sounding data and local geodynamic activity

    NASA Astrophysics Data System (ADS)

    Kugaenko, Yu. A.; Saltykov, V. A.; Gorbatikov, A. V.; Stepanova, M. Yu.

    2015-05-01

    The model of the magmatic system beneath the Uzon-Geizernaya volcano-tectonic depression and adjacent Kikhpinych volcano in Kamchatka is constructed to a depth of 30 km based on the microseismic sounding data. For doing this, measurements of the natural microseismic field by the Guralp CMG-6TD portable broadband seismometer were carried out at 60 points along three profiles with a total length of about 28 km. The revealed structural heterogeneities were interpreted in the common context with the previous geological, geological-morphological, and petrological results. The area of a shallow crystallized magmatic reservoir is identified and spatially localized below the depression. The zones of the presumed concentration of the basaltic melts probably responsible for the local geodynamic activation of the region during the past 15 years are revealed as the peripheral magmatic chamber of the Kikhpinych volcano at a depth of 5-12 km and a deeper (15-20 km) magma storage. The geometry of the identified deep structures is consistent with the local microseismicity and the model of the contemporary magmatic intrusion into the upper crustal layers, which is based on the data of satellite interferometry.

  17. Object-oriented classification of a high-spatial resolution SPOT5 image for mapping geology and landforms of active volcanoes: Semeru case study, Indonesia

    NASA Astrophysics Data System (ADS)

    Kassouk, Zeineb; Thouret, Jean-Claude; Gupta, Avijit; Solikhin, Akhmad; Liew, Soo Chin

    2014-09-01

    The present work explores the object-oriented classification (OOC) of high-spatial resolution (HSR) satellite panchromatic imagery for mapping the geology of the persistently active Semeru volcano and its ring plain, east Java, Indonesia. A panchromatic SPOT5 image and a digital elevation model (DEM) have been used to identify geologic units, structures, landforms and deposits. The panchromatic image was georeferenced and enhanced using histogram equalization. The enhanced image was segmented into polygons using the EnviFx (©Exelis) Software. The polygons were delineated and classified on the basis of spectral (panchromatic hues and textures), topographic (slope, elevation) information and geologic/geomorphic processes. The validity of classification was evaluated by interpreting Google Earth images, aerial photographs and limited field observations. The classification consists of three hierarchical levels across the volcanic area of about 745 km2. The first operational spatial level includes seven large volcano domains based on the spectral content of the volcanic, tectonic and lithological structures, and principal catchments. The second operational level, based on contextual relationships (topography, drainage network, vegetation cover type, stratigraphy and slope dynamics), encompasses 20 geological units that range between 30 and 80 km2 in area. Among the units, the third operational level distinguishes as many as 47 geomorphological sub-units (0.25-25 km2) according to slope gradient, deposit type, mass-wasting process and weathering. The resulting map provides a detailed pattern of geologic and geomorphic features unlike previous geologic maps that identified only 11 stratigraphic units. We show that the high-spatial resolution panchromatic SPOT5 scene can help to safely map the geology and landforms of persistently active volcanoes such as Semeru. We have applied the OOC technique on one HSR GeoEye panchromatic image to map another active volcano, Merapi

  18. Seismic Activity Related to the 2002-2003 Mt. Etna Volcano Eruption (Italy): Fault Plane Solutions and Stress Tensor Computation

    NASA Astrophysics Data System (ADS)

    Barberi, G.; Cammarata, L.; Cocina, O.; Maiolino, V.; Musumeci, C.; Privitera, E.

    2003-04-01

    Late on the night of October 26, 2002, a bi-lateral eruption started on both the eastern and the southeastern flanks of Mt. Etna. The opening of the eruptive fracture system on the NE sector and the reactivation of the 2001 fracture system, on the S sector, were accompanied by a strong seismic swarm recorded between October 26 and 28 and by sharp increase of volcanic tremor amplitude. After this initial phase, on October 29 another seismogenetic zone became active in the SE sector of the volcano. At present (January 2003) the eruption is still in evolution. During the whole period a total of 862 earthquakes (Md≫1) was recorded by the local permanent seismic network run by INGV - Sezione di Catania. The maximum magnitude observed was Md=4.4. We focus our attention on 55 earthquakes with magnitude Md≫ 3.0. The dataset consists of accurate digital pickings of P- and S-phases including first-motion polarities. Firstly earthquakes were located using a 1D velocity model (Hirn et alii, 1991), then events were relocated by using two different 3D velocity models (Aloisi et alii, 2002; Patane et alii, 2002). Results indicate that most of earthquakes are located to the east of the Summit Craters and to northeast of them. Fault plane solutions (FPS) obtained show prevalent strike-slip rupture mechanisms. The suitable FPSs were considered for the application of Gephart and Forsyth`s algorithm in order to evaluate seismic stress field characteristics. Taking into account the preliminary results we propose a kinematic model of the eastern flank eastward movement in response of the intrusion processes in the central part of the volcano. References Aloisi M., Cocina O., Neri G., Orecchio B., Privitera E. (2002). Seismic tomography of the crust underneath the Etna volcano, Sicily. Physics of the Earth and Planetary Interiors 4154, pp. 1-17 Hirn A., Nercessian A., Sapin M., Ferrucci F., Wittlinger G. (1991). Seismic heterogeneity of Mt. Etna: structure and activity. Geophys. J

  19. Degassing processes and eruptive activity at Merapi volcano: The bearing of short-lived U-series isotopes.

    NASA Astrophysics Data System (ADS)

    Gauthier, P. J.; Le Cloarec, M. F.

    2003-04-01

    For more than 20 years, volcanic gases have been regularly collected at Merapi volcano (Central Java, Indonesia) and subsequently analyzed for their radionuclide (210Pb, 210Bi, and 210Po) and SO_2 contents. Gas sampling was carried out during various periods of contrasted volcanic activity and at different locations: high-temperature fumarolic fields (Woro: 600^oC; Gendol 850^oC), main plume released through fractures within the summit crater, and active growing lava domes. These new results show the high volatility of the three radionuclides in andesitic gases, although their emanation coefficients (0.94%, 3.5%, and <= 53% for 210Pb, 210Bi, and 210Po, respectively) are significantly lower than those observed at basaltic volcanoes. This emphasizes the major role of magma temperature on the degassing of these metals, which are mainly transported in volcanic gases as Pb-chloride compounds, and Bi- and Po-metallic species. 210Pb--210Bi--210Po radioactive disequilibria in the gas phase at Merapi appear to be characteristic of the degassing processes and gas paths within the edifice. Gases released at both Gendol and Woro fumarolic fields are clearly of magmatic origin, but their 210Pb--210Bi--210Po isotopic signature is strongly altered by secondary processes: condensation and transformation of gases crossing brines (Woro); deposition and subsequent degassing of sublimates according to temperature variations in the ground (Woro, Gendol). High-temperature gases collected in the main plume are of pure primary magmatic origin. They are likely directly tapped in the degassing reservoir and escape through the main fractures with little interaction with the dome-forming host rocks. On the other hand, gases arising from the growing dome are strongly depleted in the most volatile isotopes and gas species. We conclude from these observations that lava is almost completely degassed prior to its emission at the surface, and that magmatic degassing at Merapi is an open

  20. A glassy lava flow from Toconce volcano and its relation with the Altiplano-Puna Magma Body in Central Andes

    NASA Astrophysics Data System (ADS)

    Godoy, B.; Rodriguez, I.; Aguilera, F.

    2012-12-01

    Toconce is a composite stratovolcano located at the San Pedro - Linzor volcanic chain (SPLVC). This volcanic chain distributes within the Altiplano-Puna region (Central Andes) which is characterized by extensive rhyodacitic-to-rhyolitic ignimbritic fields, and voluminous domes of dacitic-to-rhyolitic composition (de Silva, 1989). The felsic melts that gave origin to ignimbrites and domes at this area were generated by mixing of mantle-derived magmas and anatectic melts assimilated during their ascent through the thick crust. Thus, partially molten layers exist in the upper crust below the APVC (de Silva et al., 2006). Evidence of large volumes of such melts has been also proposed by geophysical methods (i.e. the Altiplano-Puna Magma Body; Chmielowsky et al., 1999) In this work, petrography and whole rock, mineralogical and melt inclusions geochemistry of a glassy lava flow of Toconce volcano are presented. Petrographically, this lava flow shows a porphyric texture, with euhdral to subhedral plagioclase, ortho- and clino-pyroxene phenocrysts immersed in a glassy groundmass. Geochemically, the lava flow has 64.7% wt. SiO2. The glassy groundmass (~70% wt. SiO2) is more felsic than all the lavas in the volcanic chain (47-68% wt., Godoy et al., 2011). Analyzed orthopyroxene-hosted melt inclusions show an even higher SiO2 content (72-75% wt.), and a decreasing on Al2O3, Na2O, and CaO content with differentiation. Crystallization pressures of this lava flow, obtained using Putirka's two-pyroxene and clinopyroxene-liquid models (Putirka, 2008), range between 6 and 9 kbar. According to crystallization pressures, and major element composition, a felsic source located at shallow crustal pressures - where plagioclase is a stable mineralogical phase - originated the inclusions. This could be related to the presence of the Altiplano-Puna Magma Body (APMB) located below SPLVC. On the other hand, glassy groundmass, and disequilibrium textures in minerals of this lava flow could

  1. Late Holocene stratigraphy of the Tetimpa archaeological sites, northeast flank of Popocatepetl volcano, central Mexico

    USGS Publications Warehouse

    Panfil, M.S.; Gardner, T.W.; Hirth, K.G.

    1999-01-01

    Late Holocene (240 km2 on the east side of the volcano with >25 cm of tephra. Lavas from eruptive sequence I dammed drainage in the lowland area near the town of San Nicolas and caused local upstream deposition of as much as 30 m of lacustrine silts, clays, and sands. These lacustrine deposits record an eruptive hiatus for the Tetimpa area of about 750 14C yr: between ca. 2100 and ca. 1350 yr B.P., no major tephras were deposited in the Tetimpa area. In upland areas, this time period is represented by an unconformity and by Entisols formed in the top of pumice deposits and lavas from eruptive sequence I. Artifacts, agricultural furrows, and dwellings record human reoccupation of this surface. At the end of this hiatus, several lahars were deposited above the lacustrine sequence and locally above the Entisol in upland positions adjacent to streams. Between ca. 1350 and ca. 1200 yr B.P., tephras from eruptive sequence II buried these paleosols, occupation sites, lacustrine sediments, and lahars. Andesitic (~62% SiO2) pumice lapilli deposits in the Tetimpa area record three pumice-fall eruptions directed northeast and east of the crater. The first and smallest of these (maximum Tetimpa area thickness = 12 cm; >52 km2 covered by >25 cm) took place at ca. 1350 yr B.P. and was accompanied by pyroclastic surge events preserved in the Tetimpa area by charcoal, sand waves, and cross-stratified sand-sized tephra. At ca. 1200 yr B.P., the products of two Plinian-style events and additional pyroclastic surges reached the Tetimpa area. The largest of these tephra-fall events covered the Tetimpa area with 0.5-1 m of tephra and blanketed an area of >230 km2 with a thickness of >25 cm. The Tetimpa record confirms two of the four periods of explosive volcanism recognized by studies conducted around Popocatepetl in the past 30 yr. Eruptive sequence I corresponds to the explosive period between 2100 and 2500 yr B.P., and eruptive sequence II corresponds to the period between 900 and

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Morphometric, acoustic and lithofacies characterization of mud volcanoes in the Eastern Mediterranean: Toward a new approach and classification to constrain the regional distribution and activity of mud volcanoes?

    NASA Astrophysics Data System (ADS)

    Flore, Mary; Sébastien, Migeon; Elia, d'Acremont; Alain, Rabaute; Silvia, Ceramicola; Daniel, Praeg; Christian, Blanpied

    2015-04-01

    On continental margins, several types of seabed features recording fluid circulation within the sediment column have already been recognized, including mud volcanoes, pockmarks, carbonates pavements and/or mounds and brine lakes. They can be associated to (a) thermogenic or biogenic fluids migrating along tectonic conduits, (b) dissociation of gas hydrates, or (c) dewatering of turbidite channels and mass-transport deposits. Although fluid-escape structures have been analyzed for the last two decades using diverse and complementary data, many questions are still debated about their morphologies/architectures, origin and formation, their temporal dynamic and the impact of the geodynamical context on their location/formation. In the Eastern Mediterranean, fluid seepages and in particular mud volcanoes, were identified in three geodynamical contexts including active margins (Calabrian accretionary prism and Mediterranean ridge) and highly-sedimented passive margin (Nil deep-sea fan). In this study, we follow a new approach allowing to (1) better quantify a broad set of morphological parameters that characterize the seabed fluid-escape structures, (2) propose an advance classification of these structures, the final goal being to test whether one or several morphological types of fluid-escape structures can be characteristic of one tectonic and sedimentological setting in the Eastern Mediterranean basin. To achieve this classification based on geophysical and geological analysis (morphometry, reflectivity, seismic r and lithofacies features), we used a broad homogenous dataset at the scale of the Eastern Mediterranean, including multibeam bathymetry, acoustic backscatter, 2D/3D seismic reflection, and sediment cores description and analysis. More than 500 mud volcano-like structures were identified based on one criterion or on the association of several criteria, while 40 of them were clearly proved to be mud volcanoes by coring. These structures exhibit different

  4. What drives centuries-long polygenetic scoria cone activity at Barren Island volcano?

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu

    2014-12-01

    Barren Island in the Andaman Sea is an active mafic stratovolcano, which had explosive and effusive eruptions, followed by caldera formation, in prehistoric time (poorly dated). A scoria cone within the caldera, marking volcanic resurgence, was active periodically from 1787 to 1832 (the historic eruptions). Since 1991, the same scoria cone has produced six eruptions, commonly including lava flows. Links between Barren Island's eruptions and giant earthquakes (such as the 26 December 2004 Great Sumatra megathrust earthquake) have been suggested, though there is no general correlation between them. The ≥ 227-year-long activity of the scoria cone, named here Shanku ("cone"), is normally driven by purely magmatic processes. I present a "source to surface" model for Barren Island and Shanku, including the source region, deeper and shallow magma chambers, volcanotectonics, dyking from magma chambers, and eruptions and eruptive style as controlled by crustal stresses, composition and volatile content. Calculations show that dykes ~ 0.5 m thick and a few hundred meters long, originating from shallow-level magma chambers (~ 5 km deep), are suitable feeders of the Shanku eruptions. Shanku, a polygenetic scoria cone (at least 13 eruptions since 1787), has three excellent analogues, namely Anak Krakatau (40 eruptions since 1927), Cerro Negro (23 eruptions since 1850), and Yasur (persistent activity for the past hundreds of years). This is an important category of volcanoes, gradational between small "monogenetic" scoria cones and larger "polygenetic" volcanoes.

  5. Source mechanism of very-long-period signals accompanying dome growth activity at Merapi volcano, Indonesia

    USGS Publications Warehouse

    Hidayat, D.; Chouet, B.; Voight, B.; Dawson, P.; Ratdomopurbo, A.

    2002-01-01

    Very-long-period (VLP) pulses with period of 6-7s, displaying similar waveforms, were identified in 1998 from broadband seismographs around the summit crater. These pulses accompanied most of multiphase (MP) earthquakes, a type of long-period event locally defined at Merapi Volcano. Source mechanisms for several VLP pulses were examined by applying moment tensor inversion to the waveform data. Solutions were consistent with a crack striking ???70?? and dipping ???50?? SW, 100m under the active dome, suggest pressurized gas transport involving accumulation and sudden release of 10-60 m3 of gas in the crack over a 6s interval.

  6. Source mechanism of very-long-period signals accompanying dome growth activity at Merapi volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Hidayat, D.; Chouet, B.; Voight, B.; Dawson, P.; Ratdomopurbo, A.

    2002-12-01

    Very-long-period (VLP) pulses with period of 6-7s, displaying similar waveforms, were identified in 1998 from broadband seismographs around the summit crater. These pulses accompanied most of multiphase (MP) earthquakes, a type of long-period event locally defined at Merapi Volcano. Source mechanisms for several VLP pulses were examined by applying moment tensor inversion to the waveform data. Solutions were consistent with a crack striking ~70° and dipping ~50° SW, 100m under the active dome, suggest pressurized gas transport involving accumulation and sudden release of 10-60 m3 of gas in the crack over a 6s interval.

  7. Effect of subduction components on production of basalts from Tateshina volcano, central Japan: geochemical calculation of dehydration of subducting oceanic crust and partial melting of overlying sediments, and subsequent fluid-mantle interaction

    NASA Astrophysics Data System (ADS)

    Katoh, Masayasu; Shuto, Kenji

    Effect of subduction components on production of basalts from Tateshina volcano, central Japan: geochemical calculation of dehydration of subducting oceanic crust and partial melting of overlying sediments, and subsequent fluid-mantle interaction

  8. 1995 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Neal, Christina A.

    1996-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptive activity or suspected volcanic activity (SVA) at 6 volcanic centers in 1995: Mount Martin (Katmai Group), Mount Veniaminof, Shishaldin, Makushin, Kliuchef/Korovin, and Kanaga. In addition to responding to eruptive activity at Alaska volcanoes, AVO also disseminated information for the Kamchatkan Volcanic Eruption Response Team (KVERT) on the 1995 eruptions of 2 Russian volcanoes: Bezymianny and Karymsky. This report summarizes volcanic activity in Alaska during 1995 and the AVO response, as well as information on the 2 Kamchatkan eruptions. Only those reports or inquiries that resulted in a "significant" investment of staff time and energy (here defined as several hours or more for reaction, tracking, and follow-up) are included. AVO typically receives dozens of phone calls throughout the year reporting steaming, unusual cloud sightings, or eruption rumors. Most of these are resolved quickly and are not tabulated here as part of the 1995 response record.

  9. The ~ 31 ka rhyolitic Plinian to sub-Plinian eruption of Tlaloc Volcano, Sierra Nevada, central Mexico

    NASA Astrophysics Data System (ADS)

    Rueda, H.; Macías, J. L.; Arce, J. L.; Gardner, J. E.; Layer, P. W.

    2013-02-01

    Tlaloc is a late Pleistocene stratovolcano located NE of México City. It is the northernmost volcano of the N-S Sierra Nevada Volcanic Range, which consists from north to south of Tlaloc, Telapón, Iztaccíhuatl, and Popocatépetl volcanoes. Tlaloc has always been considered the oldest (and extinct) volcano of the Sierra Nevada Volcanic Range. Recent field data revealed that Tlaloc was very active during late Pleistocene through a series of explosive eruptions. One of these eruptions produced the Multilayered White Pumice (MWP) a rhyolitic pyroclastic sequence. The eruption began with a 24-km high Plinian column MWP-F1 that was dispersed to the NE by prevailing winds. It was interrupted by fountaining of the column with the generation of a pyroclastic density current that emplaced MWP-S1 layer. Then, followed five unstable sub-Plinian columns (MWP-F2 to F6) that reached altitudes between 16 and 19 km. Fall deposits as a whole are 1 m thick at 12 km from the vent, cover a minimum area of 577 km2 for a total volume of 4.68 km3 (DRE 1.58 km3). The eruption ejected a total mass of 3.45 × 1012 kg at different mass discharges. The last sub-Plinian column (MWP-F6) collapsed and produced dense pyroclastic density currents that deposited pumiceous pyroclastic flows (MWP-PF) following main ravines to the north and east of the vent. These density currents filled gullies with 23 m-thick deposits at a distance of 12 km from the vent totaling a minimum DRE volume of 0.2 km3. Pyroclastic flow deposits charred tree trunks that yielded an age of 31,490 + 1995/- 1595 yr B.P. that closely date the age of the eruption. Rain during this phase of the eruption generated syn-eruptive lahars (MWP-DF). Post-eruptive lahars (MWP-ED) finally swept the volcano flanks. The MWP deposits consist of abundant white pumice (up to 96 vol.%), rare gray pumice, cognate lithics, accidental altered lithics, xenocrysts. White and gray pumice clasts contain phenocrysts of quartz, plagioclase, sanidine

  10. Observing active deformation of volcanoes in North America: Geodetic data from the Plate Boundary Observatory and associated networks

    NASA Astrophysics Data System (ADS)

    Puskas, C. M.; Phillips, D. A.; Mattioli, G. S.; Meertens, C. M.; Hodgkinson, K. M.; Crosby, C. J.; Enders, M.; Feaux, K.; Mencin, D.; Baker, S.; Lisowski, M.; Smith, R. B.

    2013-12-01

    The EarthScope Plate Boundary Observatory (PBO), operated by UNAVCO, records deformation of the geologically diverse North America western plate boundary, with subnetworks of instruments concentrated at selected active and potentially active volcanoes. These sensors record deformation and earthquakes and allow monitoring agencies and researchers to analyze changes in ground motion and seismicity. The intraplate volcanoes at Yellowstone and Long Valley are characterized by uplift/subsidence cycles, high seismicity, and hydrothermal activity but there have been no historic eruptions at either volcano. PBO maintains dense GPS networks of 20-25 stations at each of these volcanoes, with an additional 5 boreholes at Yellowstone containing tensor strainmeters, short-period seismometers, and borehole tiltmeters. Subduction zone volcanoes in the Aleutian Arc have had multiple historic eruptions, and PBO maintains equipment at Augustine (8 GPS), Akutan (8 GPS, 4 tiltmeters), and Unimak Island (14 GPS, 8 tiltmeters). The Unimak stations are at the active Westdahl and Shishaldin edifices and the nearby, inactive Isanotski volcano. In the Cascade Arc, PBO maintains networks at Mount St. Helens (15 GPS, 4 borehole strainmeters and seismometers, 8 borehole tiltmeters), Shasta (7 GPS, 1 borehole strainmeter and seismometer), and Lassen Peak (8 GPS). Data from many of these stations in the Pacific Northwest and California are also provided as realtime streams of raw and processed data. Real-time GPS data, along with high-rate GPS data, will be an important new resource for detecting and studying future rapid volcanic deformation events and earthquakes. UNAVCO works closely with the USGS Volcano Hazards Program, archiving data from USGS GPS stations in Alaska, Cascadia, and Long Valley. The PBO and USGS networks combined provide more comprehensive coverage than PBO alone, particularly of the Cascade Arc, where the USGS maintains a multiple instruments near each volcano. Ground

  11. Vailulu’u Seamount, Samoa: Life and death on an active submarine volcano

    PubMed Central

    Staudigel, Hubert; Hart, Stanley R.; Pile, Adele; Bailey, Bradley E.; Baker, Edward T.; Brooke, Sandra; Connelly, Douglas P.; Haucke, Lisa; German, Christopher R.; Hudson, Ian; Jones, Daniel; Koppers, Anthony A. P.; Konter, Jasper; Lee, Ray; Pietsch, Theodore W.; Tebo, Bradley M.; Templeton, Alexis S.; Zierenberg, Robert; Young, Craig M.

    2006-01-01

    Submersible exploration of the Samoan hotspot revealed a new, 300-m-tall, volcanic cone, named Nafanua, in the summit crater of Vailulu’u seamount. Nafanua grew from the 1,000-m-deep crater floor in <4 years and could reach the sea surface within decades. Vents fill Vailulu’u crater with a thick suspension of particulates and apparently toxic fluids that mix with seawater entering from the crater breaches. Low-temperature vents form Fe oxide chimneys in many locations and up to 1-m-thick layers of hydrothermal Fe floc on Nafanua. High-temperature (81°C) hydrothermal vents in the northern moat (945-m water depth) produce acidic fluids (pH 2.7) with rising droplets of (probably) liquid CO2. The Nafanua summit vent area is inhabited by a thriving population of eels (Dysommina rugosa) that feed on midwater shrimp probably concentrated by anticyclonic currents at the volcano summit and rim. The moat and crater floor around the new volcano are littered with dead metazoans that apparently died from exposure to hydrothermal emissions. Acid-tolerant polychaetes (Polynoidae) live in this environment, apparently feeding on bacteria from decaying fish carcasses. Vailulu’u is an unpredictable and very active underwater volcano presenting a potential long-term volcanic hazard. Although eels thrive in hydrothermal vents at the summit of Nafanua, venting elsewhere in the crater causes mass mortality. Paradoxically, the same anticyclonic currents that deliver food to the eels may also concentrate a wide variety of nektonic animals in a death trap of toxic hydrothermal fluids. PMID:16614067

  12. Remote observations of eruptive clouds and surface thermal activity during the 2009 eruption of Redoubt volcano

    NASA Astrophysics Data System (ADS)

    Webley, P. W.; Lopez, T. M.; Ekstrand, A. L.; Dean, K. G.; Rinkleff, P.; Dehn, J.; Cahill, C. F.; Wessels, R. L.; Bailey, J. E.; Izbekov, P.; Worden, A.

    2013-06-01

    Volcanoes often erupt explosively and generate a variety of hazards including volcanic ash clouds and gaseous plumes. These clouds and plumes are a significant hazard to the aviation industry and the ground features can be a major hazard to local communities. Here, we provide a chronology of the 2009 Redoubt Volcano eruption using frequent, low spatial resolution thermal infrared (TIR), mid-infrared (MIR) and ultraviolet (UV) satellite remote sensing data. The first explosion of the 2009 eruption of Redoubt Volcano occurred on March 15, 2009 (UTC) and was followed by a series of magmatic explosive events starting on March 23 (UTC). From March 23-April 4 2009, satellites imaged at least 19 separate explosive events that sent ash clouds up to 18 km above sea level (ASL) that dispersed ash across the Cook Inlet region. In this manuscript, we provide an overview of the ash clouds and plumes from the 19 explosive events, detailing their cloud-top heights and discussing the variations in infrared absorption signals. We show that the timing of the TIR data relative to the event end time was critical for inferring the TIR derived height and true cloud top height. The ash clouds were high in water content, likely in the form of ice, which masked the negative TIR brightness temperature difference (BTD) signal typically used for volcanic ash detection. The analysis shown here illustrates the utility of remote sensing data during volcanic crises to measure critical real-time parameters, such as cloud-top heights, changes in ground-based thermal activity, and plume/cloud location.

  13. Relationship between fumarole gas composition and eruptive activity at Galeras Volcano, Colombia

    SciTech Connect

    Fischer, T.P.; Williams, S.N.; Arehart, G.B.; Sturchio, N.C.

    1996-06-01

    Forecasting volcanic eruptions is critical to the mitigation of hazards for the millions of people living dangerously close to active volcanoes. Volcanic gases collected over five years from Galeras Volcano, Colombia, and analyzed for chemical and isotopic composition show the effects of long-term degassing of the magma body and a gradual decline in sulfur content of the gases. In contrast, short-term (weeks), sharp variations are the precursors to explosive eruptions. Selective absorption of magmatic SO{sub 2} and HCl due to interaction with low-temperature geothermal waters allows the gas emissions to become dominated by CO{sub 2}. Absorption appears to precede an eruption because magmatic volatiles are slowed or retained by a sealing carapace, reducing the total flux of volatiles and allowing the hydrothermal volatiles to dominate gas emissions. Temporal changes in gas compositions were correlated with eruptive activity and provide new evidence bearing on the mechanism of this type of `pneumatic` explosive eruptions. 18 refs., 5 figs.

  14. Seismic image of a CO2 reservoir beneath a seismically active volcano

    USGS Publications Warehouse

    Julian, B.R.; Pitt, A.M.; Foulger, G.R.

    1998-01-01

    Mammoth Mountain is a seismically active volcano 200 000 to 50 000 years old, situated on the southwestern rim of Long Valley caldera, California. Since 1989 it has shown evidence of unrest in the form of earthquake swarms (Hill et al. 1990), volcanic 'long-period' earthquakes (Pitt and Hill 1994), increased output of magmatic 3He (Sorey et al. 1993) and the emission of about 500 tonnes day-1 of CO2 (Farrar et al. 1995; Hill 1996; M. Sorey, personal communication, 1997) which has killed trees and poses a threat to human safety. Local-earthquake tomography shows that in mid-1989 areas of subsequent tree-kill were underlain by extensive regions where the ratio of the compressional and shear elastic-wave speeds Vp/VS was about 9% lower than in the surrounding rocks. Theory (Mavko and Mukerji 1995), experiment (Ito, DeVilbiss and Nur 1979) and experience at other geothermal/volcanic areas (Julian et al. 1996) and at petroleum reservoirs (Harris et al. 1996) indicate that Vp/VS is sensitive to pore-fluid compressibility, through its effect on Vp. The observed Vp/VS anomaly is probably caused directly by CO2, and seismic Vp/VS tomography is thus a promising tool for monitoring gas concentration and movement in volcanoes, which may in turn be related to volcanic activity.

  15. How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

    NASA Astrophysics Data System (ADS)

    Corbi, F.; Rivalta, E.; Pinel, V.; Maccaferri, F.; Bagnardi, M.; Acocella, V.

    2015-12-01

    Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we show with numerical models that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Galápagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observations. We then develop a general model for the stress state at volcanic edifices with calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control: 1) the shallow accumulation of magma in stacked sills, consistently with observations; 2) the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

  16. Development of an automatic volcanic ash sampling apparatus for active volcanoes

    NASA Astrophysics Data System (ADS)

    Shimano, Taketo; Nishimura, Takeshi; Chiga, Nobuyuki; Shibasaki, Yoshinobu; Iguchi, Masato; Miki, Daisuke; Yokoo, Akihiko

    2013-12-01

    We develop an automatic system for the sampling of ash fall particles, to be used for continuous monitoring of magma ascent and eruptive dynamics at active volcanoes. The system consists of a sampling apparatus and cameras to monitor surface phenomena during eruptions. The Sampling Apparatus for Time Series Unmanned Monitoring of Ash (SATSUMA-I and SATSUMA-II) is less than 10 kg in weight and works automatically for more than a month with a 10-kg lead battery to obtain a total of 30 to 36 samples in one cycle of operation. The time range covered in one cycle varies from less than an hour to several months, depending on the aims of observation, allowing researchers to target minute-scale fluctuations in a single eruptive event, as well as daily to weekly trends in persistent volcanic activity. The latest version, SATSUMA-II, also enables control of sampling parameters remotely by e-mail commands. Durability of the apparatus is high: our prototypes worked for several months, in rainy and typhoon seasons, at windy and humid locations, and under strong sunlight. We have been successful in collecting ash samples emitted from Showa crater almost everyday for more than 4 years (2008-2012) at Sakurajima volcano in southwest Japan.

  17. Seismic image of a CO2 reservoir beneath a seismically active volcano

    NASA Astrophysics Data System (ADS)

    Julian, Bruce R; Pitt, A. M.; Foulger, G. R.

    1998-04-01

    Mammoth Mountain is a seismically active volcano 200000 to 50000 years old, situated on the southwestern rim of Long Valley caldera, California. Since 1989 it has shown evidence of unrest in the form of earthquake swarms (Hill et al. 1990), volcanic `long-period' earthquakes (Pitt & Hill 1994), increased output of magmatic 3He (Sorey et al. 1993) and the emission of about 500 tonnes day -1 of CO2 (Farrar et al. 1995; Hill 1996; M. Sorey, personal communication, 1997), which has killed trees and poses a threat to human safety. Local-earthquake tomography shows that in mid-1989 areas of subsequent tree-kill were underlain by extensive regions where the ratio of the compressional and shear elastic-wave speeds VP/VS was about 9 per cent lower than in the surrounding rocks. Theory (Mavko & Mukerji 1995), experiment (Ito, DeVilbiss & Nur 1979), and experience at other geothermal/volcanic areas (Julian et al. 1996) and at petroleum reservoirs (Harris et al. 1996) indicate that VP/VS is sensitive to pore-fluid compressibility, through its effect on VP . The observed VP/VS anomaly is probably caused directly by CO2, and seismic VP/VS tomography is thus a promising tool for monitoring gas concentration and movement in volcanoes, which may in turn be related to volcanic activity.

  18. SO2 Emissions at Semeru Volcano, Indonesia: Characterization and Quantification of Persistent and Periodic Explosive Activity.

    NASA Astrophysics Data System (ADS)

    Smekens, J. F.; Clarke, A. B.; Burton, M. R.; Harijoko, A.; Wibowo, H.

    2014-12-01

    We present the first measurements of SO2 emissions at Semeru volcano, Indonesia, using an SO2 camera. Activity at Semeru is characterized by quiescent degassing interspersed with short-lived explosive events with low ash burden. The interval between explosions was measured at 32.1±15.7 minutes in a webcam survey of the volcano between the months of June and December 2013. We distinguish between two types of events: shorter events (type I: ~5 mins duration) with emissions returning quickly to baseline levels, and longer events (type II: ~15 mins duration) often showing multiple pulses and a longer period of increased emissions before a return to quiescent levels. Type I events represent >90% of the activity and release an average of 200-450 kg of SO2 per event. The single type II event we documented with the SO2 camera released a total of 1300 kg of SO2. We estimate the daily average emissions of Semeru to be 21-60 t d-1 of SO2, amounting to a yearly output of 7.5-22 Gg (7,500 - 22,000 metric tons), with 35-60% released during explosive events. The time series patterns of degassing are consistent with the existence of a viscous plug at the top of the conduit, causing accumulation and pressurization of the magma to produce the explosive events.

  19. SO2 emissions at Semeru volcano, Indonesia: Characterization and quantification of persistent and periodic explosive activity

    NASA Astrophysics Data System (ADS)

    Smekens, Jean-François; Clarke, Amanda B.; Burton, Michael R.; Harijoko, Agung; Wibowo, Haryo E.

    2015-07-01

    We present the first measurements of SO2 emissions at Semeru volcano, Indonesia, using an SO2 camera. Activity at Semeru is characterized by quiescent degassing interspersed with short-lived explosive events with low ash burden. The interval between explosions was measured at 32.1 ± 15.7 min in a webcam survey of the volcano between the months of June and December 2013. We distinguish between two types of events: shorter events (type I: ~ 5 min duration) with emissions returning quickly to baseline levels, and longer events (type II: ~ 15 min duration) often showing multiple pulses and a longer period of increased emissions before a return to quiescent levels. Type I events represent > 90% of the activity and release an average of 200-500 kg of SO2 per event. The single type II event we documented with the SO2 camera released a total of 1460 kg of SO2. We estimate the daily average emissions of Semeru to be 21-71 t d- 1 of SO2, amounting to a yearly output of 8-26 Gg (8000-26,000 metric tons), with 35-65% released during explosive events. The time series patterns of degassing are consistent with the existence of a viscous plug at the top of the conduit, which seals the conduit immediately prior to explosive events, causing pressurization of the underlying magma followed by a sudden release of gas and fragmented magma.

  20. Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems

    PubMed Central

    Tassi, Franco; Montegrossi, Giordano; Capecchiacci, Francesco; Vaselli, Orlando

    2010-01-01

    The composition of non-methane organic volatile compounds (VOCs) determined in 139 thermal gas discharges from 18 different geothermal and volcanic systems in Italy and Latin America, consists of C2–C20 species pertaining to the alkanes, alkenes, aromatics and O-, S- and N-bearing classes of compounds. Thiophenes and mono-aromatics, especially the methylated species, are strongly enriched in fluids emissions related to hydrothermal systems. Addition of hydrogen sulphide to dienes and electrophilic methylation involving halogenated radicals may be invoked for the formation of these species. On the contrary, the formation of furans, with the only exception of C4H8O, seems to be favoured at oxidizing conditions and relatively high temperatures, although mechanisms similar to those hypothesized for the production of thiophenes can be suggested. Such thermodynamic features are typical of fluid reservoirs feeding high-temperature thermal discharges of volcanoes characterised by strong degassing activity, which are likely affected by conspicuous contribution from a magmatic source. The composition of heteroaromatics in fluids naturally discharged from active volcanoes and geothermal areas can then be considered largely dependent on the interplay between hydrothermal vs. magmatic contributions. This implies that they can be used as useful geochemical tools to be successfully applied in both volcanic monitoring and geothermal prospection. PMID:20480029

  1. Precursory Activity of the 2005 Eruption of Santa Ana Volcano, El Salvador.

    NASA Astrophysics Data System (ADS)

    Colvin, A.; Patrick, M.; Rose, W. I.; Escobar, D.; Montalvo, F.; Gutierrez, E.; Olmos, R.

    2007-12-01

    After a period of unrest, Santa Ana (Illamatepec) volcano in El Salvador erupted suddenly on October 1st, 2005 at 1420 UTC (0820 local time), ejecting its acidic crater lake and generating a gas-and-ash plume ~10 km above the volcano. The short-lived eruption (~1 hr duration) deposited ballistics and ash up to 5m thick at the crater rim and depositing ash up to 40 km to the west. Underlying phreatomagmatic deposits exposed in the crater suggest that larger eruptions of this type are characteristic of recent historic activity. In this study, precursory activity to the 2005 eruption is investigated by analyzing physical and chemical parameters of the crater lake. Data has been compiled on water chemistry, temperature, and color of the lake from direct sampling and ground observations from 2004-2007. Lake water data suggests three phases of activity: (1) constant, well constrained activity from Jan. 2004 to Dec. 2004 showing SO4 ~10,000 ppm, Cl ~6000 ppm, and SO4/Cl ~1.6; (2) potential precursory activity from Jan. 2005 to Oct. 2005 expressed as a ramping up of SO4 to 11,625 ppm in May with a sudden decrease to 8250 ppm one month later, increased variability in Cl, and color change from dark coffee color to green in mid-September; and (3) post- eruption activity to present showing increasing Cl to a maximum of 22340 ppm, low SO4/Cl=0.38-0.8, an increase in temperature to 65.6 degrees C, and color change to yellowish-green). Analysis of high resolution satellite imagery from the ASTER sensor (15-90m/pixel) from 2000 to 2007 provides further information on lake size, temperature, and color. ASTER images show that the lake re-established itself further to the west after the eruption, drowning the adjacent high temperature fumarole field (max. 875 degrees C) which potentially contributed to the observed post-eruption changes in the lake. The combination of synoptic satellite-based remote sensing data with ground measurements will enhance the capabilities to recognize and

  2. Gravity and deformation changes at two persistently active volcanoes: Insights into magmatic processes

    NASA Astrophysics Data System (ADS)

    Williams-Jones, G.; Rymer, H.

    2004-05-01

    Insights on some of the mechanisms responsible for persistent volcanism can be best achieved through the synergy of temporal geophysical and geochemical data sets. Gravity changes combined with ground deformation have been shown to provide important information on magma reservoir mass changes while measurements of gas flux have been influential in determining the rate of magma emplacement. The integration of long-term micro-gravity and ground deformation data with SO2 flux and total sulphur budgets collected at Poás and Masaya volcanoes (since 1983 and 1993, respectively) now allows for the identification of significant cycles of activity. Recent eruptive activity at Poás volcano (Costa Rica) has been characterised by the disappearance and subsequent reappearance of the summit crater lake following intrusive episodes in 1980 and 1986-1989. Magma approached the surface on both occasions and was detected by the observation of concurrent increases in micro-gravity. These increases can be best modelled in terms of brittle fracturing of a shallow magma carapace allowing magma ascent through the conduit system to beneath the crater. This process allows for the vertical transfer of heat and gas and is driven by convection of buoyant, volatile-rich magma displacing colder, degassed magma. As magma pressure drops, the connection between the deeper magma reservoir and shallow conduit system is severed allowing the hydrothermal system to resume its role as a cooling mechanism. In contrast, recent activity at Masaya volcano (Nicaragua) has been characterised by repeated periods of significant passive degassing (>2000 t/d SO2) with the eruption of only negligible amounts of juvenile material. The resulting cycle gravity and gas flux variations is clearly not driven by intrusion of additional magma into the shallow system. Rather, it may be due in part to blocking and gas accumulation caused by restrictions in the shallow volcano substructure. However, as with Poás, this

  3. Stable and unstable phases of elevated seismic activity at the persistently restless Telica Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Rodgers, Mel; Roman, Diana C.; Geirsson, Halldor; LaFemina, Peter; McNutt, Stephen R.; Muñoz, Angelica; Tenorio, Virginia

    2015-01-01

    Telica Volcano, Nicaragua, is a persistently restless volcano with daily seismicity rates that can vary by orders of magnitude without apparent connection to eruptive activity. Low-frequency (LF) events are dominant and peaks in seismicity rate show little correlation with eruptive episodes, presenting a challenge for seismic monitoring and eruption forecasting. A short period seismic station (TELN) has been operated on Telica's summit since 1993, and in 2010 the installation of a six-station broadband seismic and eleven-station continuous GPS network (the TESAND network) was completed to document in detail the seismic characteristics of a persistently restless volcano. Between our study period of November 2009 and May 2013, over 400,000 events were detected at the TESAND summit station (TBTN), with daily event rates ranging from 5 to 1400. We present spectral analyses and classifications of ~ 200,000 events recorded by the TESAND network between April 2010 and March 2013, and earthquake locations for a sub-set of events between July 2010 and February 2012. In 2011 Telica erupted in a series of phreatic vulcanian explosions. Six months before the 2011 eruption, we observe a sudden decrease in LF events concurrent with a swarm of high-frequency (HF) events, followed by a decline in overall event rates, which reached a minimum at the eruption onset. We observe repeated periods of high and low seismicity rates and suggest these changes in seismicity represent repeated transitions between open-system and closed-system degassing. We suggest that these short- and long-term transitions between open to closed-system degassing form part of a long-term pattern of stable vs. unstable phases at Telica. Stable phases are characterised by steady high-rate seismicity and represent stable open-system degassing, whereas unstable phases are characterised by highly variable seismicity rates and represent repeated transitions from open to closed-system degassing, where the system is

  4. Santorini Volcano

    USGS Publications Warehouse

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

    1999-01-01

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

  5. Some insights about the activity of the Ceboruco Volcano (Nayarit, Mexico) from recent seismic low-frequency activity

    NASA Astrophysics Data System (ADS)

    Rodríguez Uribe, María Carolina; Núñez-Cornú, Francisco Javier; Nava Pichardo, Fidencio Alejandro; Suárez-Plascencia, Carlos

    2013-10-01

    The Ceboruco stratovolcano (2,280 m.a.s.l.) is located in Nayarit, Mexico, at the western end of the Mexican volcanic belt, near several population centers and by the side of a strategic highway. During the last 1,000 years it has had, on the average, one eruption every 125 years. It last eruptive activity began in 1870, and during the following 5 years it presented superficial activity including vapor emissions, ash falls, and rhyodacitic lava flows along the southeast side. A data set consisting of 139 low-frequency volcanic-type earthquakes, recorded from March 2003 to July 2008 at the CEBN triaxial short period digital station on the southwestern side of the volcano, was classified according to waveform and spectral characteristics into four families: short duration, extended coda, bobbin, and modulated amplitude. Approximate hypocentral locations indicate that there is no particular location for events of any family, but rather that all events occur at different points within the volcano. The presence of ongoing volcanic-earthquake activity together with the ongoing vapor emissions indicate that the Ceboruco volcano continues to be active, and the higher occurrence rates of short-duration events, as compared with those for the other families, could indicate an increase in the stress in the volcanic edifice. This apparent stress increase, together with the fact that the last eruption occurred 143 years ago, tell us that the Ceboruco may be approaching a critical state, and may represent a hazard to the surrounding communities and economic activities.

  6. Analysis of the seismic activity associated with the 2010 eruption of Merapi Volcano, Java

    NASA Astrophysics Data System (ADS)

    Budi-Santoso, Agus; Lesage, Philippe; Dwiyono, Sapari; Sumarti, Sri; Subandriyo; Surono; Jousset, Philippe; Metaxian, Jean-Philippe

    2013-07-01

    The 2010 eruption of Merapi is the first large explosive eruption of the volcano that has been instrumentally observed. The main characteristics of the seismic activity during the pre-eruptive period and the crisis are presented and interpreted in this paper. The first seismic precursors were a series of four shallow swarms during the period between 12 and 4 months before the eruption. These swarms are interpreted as the result of perturbations of the hydrothermal system by increasing heat flow. Shorter-term and more continuous precursory seismic activity started about 6 weeks before the initial explosion on 26 October 2010. During this period, the rate of seismicity increased almost constantly yielding a cumulative seismic energy release for volcano-tectonic (VT) and multiphase events (MP) of 7.5 × 1010 J. This value is 3 times the maximum energy release preceding previous effusive eruptions of Merapi. The high level reached and the accelerated behavior of both the deformation of the summit and the seismic activity are distinct features of the 2010 eruption. The hypocenters of VT events in 2010 occur in two clusters at of 2.5 to 5 km and less than 1.5 km depths below the summit. An aseismic zone was detected at 1.5-2.5 km depth, consistent with studies of previous eruptions, and indicating that this is a robust feature of Merapi's subsurface structure. Our analysis suggests that the aseismic zone is a poorly consolidated layer of altered material within the volcano. Deep VT events occurred mainly before 17 October 2010; subsequent to that time shallow activity strongly increased. The deep seismic activity is interpreted as associated with the enlargement of a narrow conduit by an unusually large volume of rapidly ascending magma. The shallow seismicity is interpreted as recording the final magma ascent and the rupture of a summit-dome plug, which triggered the eruption on 26 October 2010. Hindsight forecasting of the occurrence time of the eruption is performed

  7. Recent uplift and hydrothermal activity at Tangkuban Parahu volcano, west Java, Indonesia

    USGS Publications Warehouse

    Dvorak, J.; Matahelumual, J.; Okamura, A.T.; Said, H.; Casadevall, T.J.; Mulyadi, D.

    1990-01-01

    Tangkuban Parahu is an active stratovolcano located 17 km north of the city of Bandung in the province west Java, Indonesia. All historical eruptive activity at this volcano has been confined to a complex of explosive summit craters. About a dozen eruptions-mostly phreatic events- and 15 other periods of unrest, indicated by earthquakes or increased thermal activity, have been noted since 1829. The last magmatic eruption occurred in 1910. In late 1983, several small phreatic explosions originated from one of the summit craters. More recently, increased hydrothermal and earthquake activity occurred from late 1985 through 1986. Tilt measurements, using a spirit-level technique, have been made every few months since February 1981 in the summit region and along the south and east flanks of the volcano. Measurements made in the summit region indicated uplift since the start of these measurements through at least 1986. From 1981 to 1983, the average tilt rate at the edges of the summit craters was 40-50 microradians per year. After the 1983 phreatic activity, the tilt rate decreased by about a factor of five. Trilateration surveys across the summit craters and on the east flank of the volcano were conducted in 1983 and 1986. Most line length changes measured during this three-year period did not exceed the expected uncertainty of the technique (4 ppm). The lack of measurable horizontal strain across the summit craters seems to contradict the several years of tilt measurements. Using a point source of dilation in an elastic half-space to model tilt measurements, the pressure center at Tangkuban Parahu is located about 1.5 km beneath the southern part of the summit craters. This is beneath the epicentral area of an earthquake swarm that occurred in late 1983. The average rate in the volume of uplift from 1981 to 1983 was 3 million m3 per year; from 1983 to 1986 it averaged about 0.4 million m3 per year. Possible causes for this uplift are increased pressure within a very

  8. Volcanic activity observed from continuous seismic records in the region of the Klyuchevskoy group of volcanoes

    NASA Astrophysics Data System (ADS)

    Shapiro, N.; Droznin, D.; Droznina, S.; Senyukov, S.; Chebrov, V.; Gordeev, E.; Frank, W.

    2015-12-01

    We analyze continuous seismic records from 18 permanent stations operated in vicinity of the Klyuchevskoy group of volcanos (Kamchatka, Russia) during the period between 2009 and 2014. We explore the stability of the inter-station cross-correlation to detect different periods of sustained emission from seismic energy. The main idea of this approach is that cross-correlation waveforms computed from a wavefield emitted by a seismic source from a fixed position remain stable during the period when this source is acting. The detected periods of seismic emission correspond to different episodes of activity of volcanoes: Klyuchevskoy, Tolbachik, Shiveluch, and Kizimen. For Klyuchevskoy and Tolbachik whose recent eruptions are mostly effusive, the detected seismic signals correspond to typical volcanic tremor, likely caused by degassing processes. For Shiveluch and Kizimen producing more silicic lavas, the observed seismic emission often consists of many repetitive long period (LP) seismic events that might be related to the extrusion of viscous magmas. We develop an approach for automatic detection of these individual LP events in order to characterize variations of their size and recurrence in time.

  9. Tilt effects on moment tensor inversion in the near field of active volcanoes

    NASA Astrophysics Data System (ADS)

    van Driel, M.; Wassermann, J.; Pelties, C.; Schiemenz, A.; Igel, H.

    2015-09-01

    Dynamic tilts (rotational motion around horizontal axes) change the projection of local gravity onto the horizontal components of seismometers. This causes sensitivity of these components to tilt, especially at low frequencies. We analyse the consequences of this effect onto moment tensor inversion for very long period (vlp) events in the near field of active volcanoes on the basis of synthetic examples using the station distribution of a real deployed seismic network and the topography of Mt. Merapi volcano (Java, Indonesia). The examples show that for periods in the vlp range of 10-30 s tilt can have a strong effect on the moment tensor inversion, although its effect on the horizontal seismograms is significant only for few stations. We show that tilts can be accurately computed using the spectral element method and include them in the Green's functions. The (simulated) tilts might be largely influenced by strain-tilt coupling (stc). However, due to the frequency dependence of the tilt contribution to the horizontal seismograms, only the largest tilt signals affect the source inversion in the vlp frequency range. As these are less sensitive to stc than the weaker signals, the effect of stc can likely be neglected in this application. In the converse argument, this is not necessarily true for longer periods, where the horizontal seismograms are dominated by the tilt signal and rotational sensors would be necessary to account for it. As these are not yet commercially available, this study underlines the necessity for the development of such instruments.

  10. Social studies of volcanology: knowledge generation and expert advice on active volcanoes

    NASA Astrophysics Data System (ADS)

    Donovan, Amy; Oppenheimer, Clive; Bravo, Michael

    2012-04-01

    This paper examines the philosophy and evolution of volcanological science in recent years, particularly in relation to the growth of volcanic hazard and risk science. It uses the lens of Science and Technology Studies to examine the ways in which knowledge generation is controlled and directed by social forces, particularly during eruptions, which constitute landmarks in the development of new technologies and models. It also presents data from a survey of volcanologists carried out during late 2008 and early 2009. These data concern the felt purpose of the science according to the volcanologists who participated and their impressions of the most important eruptions in historical time. It demonstrates that volcanologists are motivated both by the academic science environment and by a social concern for managing the impact of volcanic hazards on populations. Also discussed are the eruptions that have most influenced the discipline and the role of scientists in policymaking on active volcanoes. Expertise in volcanology can become the primary driver of public policy very suddenly when a volcano erupts, placing immense pressure on volcanologists. In response, the epistemological foundations of volcanology are on the move, with an increasing volume of research into risk assessment and management. This requires new, integrated methodologies for knowledge collection that transcend scientific disciplinary boundaries.

  11. Capturing the fingerprint of Etna volcano activity in gravity and satellite radar data

    PubMed Central

    Negro, Ciro Del; Currenti, Gilda; Solaro, Giuseppe; Greco, Filippo; Pepe, Antonio; Napoli, Rosalba; Pepe, Susi; Casu, Francesco; Sansosti, Eugenio

    2013-01-01

    Long-term and high temporal resolution gravity and deformation data move us toward a better understanding of the behavior of Mt Etna during the June 1995 – December 2011 period in which the volcano exhibited magma charging phases, flank eruptions and summit crater activity. Monthly repeated gravity measurements were coupled with deformation time series using the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique on two sequences of interferograms from ERS/ENVISAT and COSMO-SkyMed satellites. Combining spatiotemporal gravity and DInSAR observations provides the signature of three underlying processes at Etna: (i) magma accumulation in intermediate storage zones, (ii) magmatic intrusions at shallow depth in the South Rift area, and (iii) the seaward sliding of the volcano's eastern flank. Here we demonstrate the strength of the complementary gravity and DInSAR analysis in discerning among different processes and, thus, in detecting deep magma uprising in months to years before the onset of a new Etna eruption. PMID:24169569

  12. Fiber Bragg grating strain sensors to monitor and study active volcanoes

    NASA Astrophysics Data System (ADS)

    Sorrentino, Fiodor; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvo; Giacomelli, Umberto; Grassi, Renzo; Maccioni, Enrico; Morganti, Mauro

    2016-04-01

    Stress and strain changes are among the best indicators of impending volcanic activity. In volcano geodesy, borehole volumetric strain-meters are mostly utilized. However, they are not easy to install and involve high implementation costs. Advancements in opto-electronics have allowed the development of low-cost sensors, reliable, rugged and compact, thus particularly suitable for field application. In the framework of the EC FP7 MED-SUV project, we have developed strain sensors based on the fiber Bragg grating (FBG) technology. In comparison with previous implementation of the FBG technology to study rock deformations, we have designed a system that is expected to offer a significantly higher resolution and accuracy in static measurements and a smooth dynamic response up to 100 Hz, implying the possibility to observe seismic waves. The system performances are tailored to suit the requirements of volcano monitoring, with special attention to power consumption and to the trade-off between performance and cost. Preliminary field campaigns were carried out on Mt. Etna (Italy) using a prototypal single-axis FBG strain sensor, to check the system performances in out-of-the-lab conditions and in the harsh volcanic environment (lack of mains electricity for power, strong diurnal temperature changes, strong wind, erosive ash, snow and ice during the winter time). We also designed and built a FBG strain sensor featuring a multi-axial configuration which was tested and calibrated in the laboratory. This instrument is suitable for borehole installation and will be tested on Etna soon.

  13. High-resolution seismic structure analysis of an active submarine mud volcano area off SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Hsiao-Shan; Hsu, Shu-Kun; Tsai, Wan-Lin; Tsai, Ching-Hui; Lin, Shin-Yi; Chen, Song-Chuen

    2015-04-01

    In order to better understand the subsurface structure related to an active mud volcano MV1 and to understand their relationship with gas hydrate/cold seep formation, we conducted deep-towed side-scan sonar (SSS), sub-bottom profiler (SBP), multibeam echo sounding (MBES), and multi-channel reflection seismic (MCS) surveys off SW Taiwan from 2009 to 2011. As shown in the high-resolution sub-bottom profiler and EK500 sonar data, the detailed structures reveal more gas seeps and gas flares in the study area. In addition, the survey profiles show several submarine landslides occurred near the thrust faults. Based on the MCS results, we can find that the MV1 is located on top of a mud diapiric structure. It indicates that the MV1 has the same source as the associated mud diapir. The blanking of the seismic signal may indicate the conduit for the upward migration of the gas (methane or CO2). Therefore, we suggest that the submarine mud volcano could be due to a deep source of mud compressed by the tectonic convergence. Fluids and argillaceous materials have thus migrated upward along structural faults and reach the seafloor. The gas-charged sediments or gas seeps in sediments thus make the seafloor instable and may trigger submarine landslides.

  14. Active Volcanic and Hydrothermal Processes at NW Rota-1 Submarine Volcano: Mariana Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Embley, R. W.; Baker, E. T.; Butterfield, D. A.; Chadwick, W. W.; de Ronde, C.; Dower, J.; Evans, L.; Hein, J.; Juniper, K.; Lebon, G.; Lupton, J. E.; Merle, S.; Metaxas, A.; Nakamura, K.; Resing, J. E.; Roe, K.; Stern, R.; Tunnicliffe, V.

    2004-12-01

    Dives with the remotely operated vehicle ROPOS in March/April 2004 documented a volcanic eruption at NW Rota-1, a submarine volcano of basaltic composition located at 14\\deg 36.0'N, 144\\deg 46.5'E lying 65 km northwest of Rota Island in the Commonwealth of the Northern Mariana Islands. The site was chosen as a dive target because of the of the high concentrations of H2S and alunite in the hydrothermal plume overlying its summit in February 2003. The summit of the volcano is composed of curvilinear volcanic ridge oriented NW-SE bounded by NE-SW trending normal faults. Lavas collected on the upper part of the edifice are primitive to moderately fractionated basalts (Mg# = 51-66). The eruptive activity is occurring within a small crater (Brimstone Pit) located on the upper south flank of the volcano at 550 m, about 30 m below the summit. The crater is approximately 15 m wide and at least 20 meters deep. The ROPOS's cameras observed billowing clouds of sulfur-rich fluid rising out of the crater, punctuated by frequent bursts of several minutes duration that entrained glassy volcanic ejecta up to at least 2 cm in diameter. ROPOS recorded a temperature of 38\\degC within the plume. The volcanic activity had substantial temporal variability on the scale of minutes. ROPOS was sometimes completely enveloped by the plume while on the rim of the crater, and its surfaces were coated with large sulfur droplets. Black glassy fragments were entrained in the plume up to least 50 m above the crater and deposits of this material were on ledges and tops of outcrops up to several hundred meters from Brimstone Pit. The pit crater fluids have an extremely high content of particulate sulfur and extremely acidic, with pH around 2.0. This strongly implicates magmatic degassing of SO2 and disproportionation into elemental S and sulfuric acid. Diffuse venting of clear fluids was also present on the summit of the volcano, with temperatures exceeding 100\\degC in volcaniclastic sands

  15. Measuring volcanic gases at Taal Volcano Main Crater for monitoring volcanic activity and possible gas hazard

    NASA Astrophysics Data System (ADS)

    Arpa, M.; Hernandez Perez, P. A.; Reniva, P.; Bariso, E.; Padilla, G.; Melian Rodriguez, G.; Barrancos, J.; Calvo, D.; Nolasco, D.; Padron, E.; Garduque, R.; Villacorte, E.; Fajiculay, E.; Perez, N.; Solidum, R.

    2012-12-01

    Taal is an active volcano located in southwest Luzon, Philippines. It consists of mainly tuff cones which have formed an island at the center of a 30 km wide Taal Caldera. Most historical eruptions, since 1572 on Taal Volcano Island, have been characterized as hydromagmatic eruptions. Taal Main Crater, produced during the 1911 eruption, is the largest crater in the island currently filled by a 1.2 km wide, 85 m deep acidic lake. The latest historical eruption occurred in 1965-1977. Monitoring of CO2 emissions from the Main Crater Lake (MCL) and fumarolic areas within the Main Crater started in 2008 with a collaborative project between ITER and PHIVOLCS. Measurements were done by accumulation chamber method using a Westsystem portable diffuse fluxmeter. Baseline total diffuse CO2 emissions of less than 1000 t/d were established for the MCL from 3 campaign-type surveys between April, 2008 to March, 2010 when seismicity was within background levels. In May, 2010, anomalous seismic activity from the volcano started and the total CO2 emission from the MCL increased to 2716±54 t/d as measured in August, 2010. The CO2 emission from the lake was highest last March, 2011 at 4670±159 t/d when the volcano was still showing signs of unrest. Because CO2 emissions increased significantly (more than 3 times the baseline value) at this time, this activity may be interpreted as magmatic and not purely hydrothermal. Most likely deep magma intrusions occurred but did not progress further to shallower depths and no eruption occurred. No large increase in lake water temperature near the surface (average for the whole lake area) during the period when CO2 was above background, it remained at 30-34°C and a few degrees lower than average ambient temperature. Total CO2 emissions from the MCL have decreased to within baseline values since October, 2011. Concentrations of CO2, SO2 and H2S in air in the fumarolic area within the Main Crater also increased in March, 2011. The measurements

  16. Estimation of total discharged mass from the phreatic eruption of Ontake Volcano, central Japan, on September 27, 2014

    NASA Astrophysics Data System (ADS)

    Takarada, Shinji; Oikawa, Teruki; Furukawa, Ryuta; Hoshizumi, Hideo; Itoh, Jun'ichi; Geshi, Nobuo; Miyagi, Isoji

    2016-08-01

    The total mass discharged by the phreatic eruption of Ontake Volcano, central Japan, on September 27, 2014, was estimated using several methods. The estimated discharged mass was 1.2 × 106 t (segment integration method), 8.9 × 105 t (Pyle's exponential method), and varied from 8.6 × 103 to 2.5 × 106 t (Hayakawa's single isopach method). The segment integration and Pyle's exponential methods gave similar values. The single isopach method, however, gave a wide range of results depending on which contour was used. Therefore, the total discharged mass of the 2014 eruption is estimated at between 8.9 × 105 and 1.2 × 106 t. More than 90 % of the total mass accumulated within the proximal area. This shows how important it is to include a proximal area field survey for the total mass estimation of phreatic eruptions. A detailed isopleth mass distribution map was prepared covering as far as 85 km from the source. The main ash-fall dispersal was ENE in the proximal and medial areas and E in the distal area. The secondary distribution lobes also extended to the S and NW proximally, reflecting the effects of elutriation ash and surge deposits from pyroclastic density currents during the phreatic eruption. The total discharged mass of the 1979 phreatic eruption was also calculated for comparison. The resulting volume of 1.9 × 106 t (using the segment integration method) indicates that it was about 1.6-2.1 times larger than the 2014 eruption. The estimated average discharged mass flux rate of the 2014 eruption was 1.7 × 108 kg/h and for the 1979 eruption was 1.0 × 108 kg/h. One of the possible reasons for the higher flux rate of the 2014 eruption is the occurrence of pyroclastic density currents at the summit area.

  17. Correcting for nucleogenic ^{36}Cl in cosmogenic ^{36}Cl dating of volcanic rocks from the Erciyes volcano, Central Turkey

    NASA Astrophysics Data System (ADS)

    Sarikaya, M. A.; Zreda, M.; Desilets, D.; Ciner, A.; Sen, E.

    2006-12-01

    Many radiometric methods are suitable for dating lava flows, but none is reliable for routine dating of lava flows younger than 10 ky. The cosmogenic ^{36}Cl method seems promising because it can be applied to any type of rock and laboratory and analytical work is easy and fast. But low cosmogenic ^{36}Cl inventory (after short exposure duration), combined with possible large non-cosmogenic component, makes this technique difficult to apply in a routine fashion. We applied the ^{36}Cl method to date a lava flow and the 14C technique to date the associated ash flow from the Erciyes (Argaeus) volcano, central Turkey. The average of three cosmogenic ^{36}Cl ages is 7.3 \\mp 0.5 ky and the average of two radiocarbon ages is 9.5 \\mp 0.3 ky (calibrated using Calib 5.0). The difference could be due to the overestimation of the calculated nucleogenic ^{36}Cl, which makes up almost one-third of the measured ^{36}Cl. If the nucleogenic component were set to zero, the average ^{36}Cl age would be 10.3 \\mp 0.2 ky. Thus, the ^{36}Cl age should be in the range between 7.3 ky and 10.2 ky, which includes the 14C age near the upper end of the interval. Under the assumption that the 14C age is correct and that the nucleogenic ^{36}Cl has reached a secular equilibrium with the magma, the nucleogenic ^{36}Cl needed to reconcile the ^{36}Cl and 14C ages is only about one-fifth of that previously calculated. In order to investigate this disparity of ages and possible calculating errors of nucleogenic ^{36}Cl, we are analyzing rock samples from where we can directly measure nucleogenic component of ^{36}Cl. This work is important for developing better ways to estimate the nucleogenic ^{36}Cl, which will improve the accuracy of ^{36}Cl dating of young volcanic rocks.

  18. Anomalous geomagnetic variations associated with the volcanic activity of the Mayon volcano, Philippines during 2009-2010

    NASA Astrophysics Data System (ADS)

    Takla, E. M.; Yoshikawa, A.; Kawano, H.; Uozumi, T.; Abe, S.

    2014-12-01

    Local anomalous geomagnetic variations preceding and accompanying the volcanic eruptions had been reported by several researchers. This paper uses continuous high-resolution geomagnetic data to examine the occurrence of any anomalous geomagnetic field variations that possibly linked with the volcanic eruption of the Mayon volcano, Philippines during 2009-2010. The nearest geomagnetic observing point from the Mayon volcano is the Legazpi (LGZ) station, Philippines; which is located about 13 km South of the Mayon volcano. The amplitude range of daily variations and the amplitude of Ultra Low Frequency emissions in the Pc3 range (Pc3; 10-45 s) were examined at the LGZ station and also were compared with those from the Davao (DAV) station, Philippines as a remote reference station. Both the LGZ and DAV stations belong to the MAGDAS Network. The result of data analysis reveals significant anomalous changes in the amplitude range of daily variations and the Pc3 amplitude at the LGZ station before and during the volcanic eruption of the Mayon volcano. From the obtained results, it appears that the observed anomalous variations are dependent on the change in the underground conductivity connected with variation in the physical properties of the Earth's crust due to the activity of the Mayon volcano. Therefore, these anomalous geomagnetic variations are considered to be of a local volcanic origin.

  19. Geochemistry of fluids emitted at the CA1 borehole (Alban Hills volcano, central Italy): new insights on deep fluids circulation and origin

    NASA Astrophysics Data System (ADS)

    Pizzino, Luca; Cinti, Daniele; Voltattorni, Nunzia; Sciarra, Alessandra; Quattrocchi, Fedora

    2010-05-01

    In the framework of a multidisciplinary project funded by the Italian Department of Civil Protection, focused on the Alban Hills volcano (Central Italy), a 350 m deep borehole (named CA1) was drilled near Santa Maria delle Mole village, adjacent to the western rim of the Tuscolano-Artemisio caldera, where several phenomena of unrest recently occurred. In the period 1989-90 a seismic swarm affected this area and a related uplift was recognized by geodetic investigations and satellite images analysis. In addition, this area is affected by high gas concentrations (mainly CO2, radon and H2S) both in aquifers and soils. Episodes of gas exhalation from soil and/or gas burst occurred in the past, causing illness and casualties among local inhabitants and animals, marking the considered area as exposed to a high Natural Gas Hazard. During the phase of hydraulic fracturing tests a blow-out occurred, allowing the collection of issuing fluids for their chemical and isotopic characterisation, in order to emphasise their origin. New geochemical data provided additional information about both the deep volcanic circulation of fluids and their possible connection to a deep-seated magma chamber. We present a general and schematic hydro-geochemical-structural model of the most degassing sector of the volcano, by merging all the information acquired in the last 15 years. Geochemical features highlight some peculiarities in both chemical and isotopic composition of the emitted fluids. Water shows a Na-HCO3 chemistry and a very high salinity never found till now throughout the Alban Hills district (TDS=7 g/l), probably due to the prolonged interaction of the CO2-rich fluids with clays. Activity plots were used to identify the main gas-water-rock interaction processes. Stable O and H isotopes reveal a meteoric origin of water, excluding any other source (juvenile and/or connate). Water is tritium-free, pointing to a long residence time of water in the aquifer. Gas phase is CO2-dominated

  20. Plume indications from hydrothermal activity on Kawio Barat Submarine Volcano, Sangihe Talaud Sea, North Sulawesi, Indonesia

    NASA Astrophysics Data System (ADS)

    Makarim, S.; Baker, E. T.; Walker, S. L.; Wirasantosa, S.; Permana, H.; Sulistiyo, B.; Shank, T. M.; Holden, J. F.; Butterfield, D.; Ramdhan, M.; Adi, R.; Marzuki, M. I.

    2010-12-01

    Kawio Barat submarine volcano has formed in response to the active tectonic conditions in Sangihe Talaud, an area that lies in the subduction zone between the Molucca Sea Plate and Celebes Sea Plate. Submarine volcanic activity in the western Sangihe volcanic arc is controlled by the west-dipping Molucca Sea Plate as it subducts beneath the Sangihe Arc. A secondary faulting system on Kawio Barat is in a northwest - southeast direction, and creates a network of deep cracks that facilitate hydrothermal discharge in this area. Hydrothermal activity on Kawio Barat was first discovered by joint Indonesia/Australian cruises in 2003. In 2010, as part of the joint US/Indonesian INDEX-SATAL expedition, we conducted CTD casts that confirmed continuing activity. Hydrothermal plumes were detected by light -scattering (LSS) and oxidation-reduction potential (ORP) sensors on the CTD package. LSS anomalies were found between 1600-1900 m, with delta NTU levels of 0.020-0.040. ORP anomalies coincident with the LSS anomalies indicate strong concentrations of reduced species such as H2S and Fe, confirming the hydrothermal origin of the plumes. Images of hydrothermal vents on Kawio Barat Submarine volcano, recorded by high- definition underwater cameras on the ROV “Little Hercules” operated from the NOAA ship Okeanos Explorer, confirmed the presence and sources of the detected vent plumes in the northern and southwest part of the summit in 1800-1900 m depth. In southwest part of this summit chimney, drips of molten sulfur were observed in the proximity of microbal staining.

  1. 2005 Volcanic Activity in Alaska, Kamchatka, and the Kurile Islands: Summary of Events and Response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, R.G.; Neal, C.A.; Dixon, J.P.; Ushakov, Sergey

    2008-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptive activity or suspected volcanic activity at or near 16 volcanoes in Alaska during 2005, including the high profile precursory activity associated with the 2005?06 eruption of Augustine Volcano. AVO continues to participate in distributing information about eruptive activity on the Kamchatka Peninsula, Russia, and in the Kurile Islands of the Russian Far East, in conjunction with the Kamchatkan Volcanic Eruption Response Team (KVERT) and the Sakhalin Volcanic Eruption Response Team (SVERT), respectively. In 2005, AVO helped broadcast alerts about activity at 8 Russian volcanoes. The most serious hazard posed from volcanic eruptions in Alaska, Kamchatka, or the Kurile Islands is the placement of ash into the atmosphere at altitudes traversed by jet aircraft along the North Pacific and Russian Trans East air routes. AVO, KVERT, and SVERT work collaboratively with the National Weather Service, Federal Aviation Administration, and the Volcanic Ash Advisory Centers to provide timely warnings of volcanic eruptions and the production and movement of ash clouds.

  2. Chlorine isotopes of thermal springs in arc volcanoes for tracing shallow magmatic activity

    NASA Astrophysics Data System (ADS)

    Li, Long; Bonifacie, Magali; Aubaud, Cyril; Crispi, Olivier; Dessert, Céline; Agrinier, Pierre

    2015-03-01

    The evaluation of the status of shallow magma body (i.e., from the final intrusion stage, to quiescence, and back to activity), one of the key parameters that trigger and sustain volcanic eruptions, has been challenging in modern volcanology. Among volatile tracers, chlorine (Cl) uniquely exsolves at shallow depths and is highly hydrophilic. Consequently, Cl enrichment in volcanic gases and thermal springs has been proposed as a sign for shallow magmatic activities. However, such enrichment could also result from numerous other processes (e.g., water evaporation, dissolution of old chloride mineral deposits, seawater contamination) that are unrelated to magmatic activity. Here, based on stable isotope compositions of chloride and dissolved inorganic carbon, as well as previous published 3He/4He data obtained in thermal springs from two recently erupted volcanoes (La Soufrière in Guadeloupe and Montagne Pelée in Martinique) in the Lesser Antilles Arc, we show that the magmatic Cl efficiently trapped in thermal springs displays negative δ37Cl values (≤ - 0.65 ‰), consistent with a slab-derived origin but distinct from the isotope compositions of chloride in surface reservoirs (e.g. seawater, local meteoric waters, rivers and cold springs) displaying common δ37Cl values of around 0‰. Using this δ37Cl difference as an index of magmatic Cl, we further examined thermal spring samples including a 30-year archive from two thermal springs in Guadeloupe covering samples from its last eruption in 1976-1977 to 2008 and an island-wide sampling event in Martinique in 2008 to trace the evolution of magmatic Cl in the volcanic hydrothermal systems over time. The results show that magmatic Cl can be rapidly flushed out of the hydrothermal systems within <30 to 80 years after the eruption, much quicker than other volatile tracers such as CO2 and noble gases, which can exsolve at greater depths and constantly migrate to the surface. Because arc volcanoes often have well

  3. Late Pleistocene to Holocene tephrostratigraphy of the Lonquimay Volcano, South Central Chile

    NASA Astrophysics Data System (ADS)

    Gilbert, D.; Freundt, A.; Kutterolf, S.; Burkert, C.

    2010-12-01

    The Lonquimay Volcanic Complex (LVC) in South Central Chile (38.38°S, 71.58°W) is part of the Southern Volcanic Zone of the Andes, which formed in response to the subduction of the Nazca Plate beneath the South American Plate. During the course of its magmatic evolution, the LVC produced explosive eruptions documented in the succession of widespread tephra deposits, as well as large lava flows that originated from the main edifice and several adjacent minor eruptive centers. The last eruptive phase in Lonquimays volcanic evolution occurred from 1988-1990. It led to the formation of the Navidad cinder cone with its associated 10.2 km long lava flow, and a widely distributed tephra blanket of andesitic composition (Moreno and Gardeweg, 1989). During recent field work we reinvestigated and complemented the LVC tephrostratigraphy as originally established by Polanco (1998)by detailed logging of 22 outcrops and collecting 126 stratigraphically controlled samples that were analyzed for their matrix glass, mineral and bulk rock compositions. This data set allows us to verify and extend the field-based correlations, and to establish a tephrostratigraphy for the LVC that comprises 15 stratigraphic units (LQA-LQO) and provides a framework for ongoing investigations of the petrogenetic evolution of the LVC. The stratigraphic record identifies at least 13 explosive eruptions of VEI > 3 that occurred since the last glaciation period (17150 a BP, McCulloch et al. 2000). Magmatic compositions of the tephra deposits range from basaltic scoriae (51wt% SiO2) to evolved dacitic pumice lapilli layers (67wt% SiO2), and thus have a wider compositional range than the chemically distinct andesitic lavas (57-63wt%) of the LVC. The vertical succession of tephra compositions reflects four periods of progressive magmatic differentiation, each successively tapped by several eruptions. The maximum degree of fractionation reached during these periods increases to younger ages. The

  4. Active high-resolution seismic tomography of compressional wave velocity and attenuation structure at Medicine Lake Volcano, northern California Cascade Range

    USGS Publications Warehouse

    Evans, J.R.; Zucca, J.J.

    1988-01-01

    Medicine Lake volcano is a basalt through rhyolite shield volcano of the Cascade Range, lying east of the range axis. The Pg wave from eight explosive sources which has traveled upward through the target volume to a dense array of 140 seismographs provides 1- to 2-km resolution in the upper 5 to 7 km of the crust beneath the volcano. The experiment tests the hypothesis that Cascade Range volcanoes of this type are underlain only by small silicic magma chambers. We image a low-velocity low-Q region not larger than a few tens of cubic kilometers in volume beneath the summit caldera, supporting the hypothesis. A shallower high-velocity high-density feature, previously known to be present, is imaged for the first time in full plan view; it is east-west elongate, paralleling a topographic lineament between Medicine Lake volcano and Mount Shasta. Differences between this high-velocity feature and the equivalent feature at Newberry volcano, a volcano in central regon resembling Medicine Lake volcano, may partly explain the scarcity of surface hydrothermal features at Medicine Lake volcano. A major low-velocity low-Q feature beneath the southeast flank of the volcano, in an area with no Holocene vents, is interpreted as tephra, flows, and sediments from the volcano deeply ponded on the downthrown side of the Gillem fault. A high-Q normal-velocity feature beneath the north rim of the summit caldera may be a small, possibly hot, subsolidus intrusion. A high-velocity low-Q region beneath the eastern caldera may be an area of boiling water between the magma chamber and the ponded east flank material. -from Authors

  5. Volcano-Tectonic Evolution of the Central Death Valley Volcanic Field - Insights Derived from the Geologic Map of the Death Valley Junction 30' x 60' Quadrangle

    NASA Astrophysics Data System (ADS)

    Thompson, R. A.; Fridrich, C.; Chan, C. F.; Zellman, K. L.; Workman, J. B.

    2014-12-01

    The geologic map of the Death Valley Junction 30' x 60' quadrangle encompasses many geologic features recording the Cenozoic volcano-tectonic evolution of central Death Valley. Most notable is the central Death Valley rhombochasm. The rhombochasm is a 65x80-km rhombic pull-apart basin complex that occupies the releasing step-over between the northern Death Valley—Furnace Creek and southern Death Valley faults. Stewart (1983) documented this feature by palinspastically restoring offset thrust fault segments and isopachs, thereby closing the rhombochasm. The central Death Valley volcanic field records the coincident and related magmatism that occurred during the extension and strike-slip strain that formed the rhombochasm. In the multi-stage evolution of this tectonomagmatic feature, changes in volcanic and structural styles, rates, and loci were synchronized, both spatially and temporally. The volcanic field covers an area of 3600 km2, and consists of >700 km3 of lava flows, domes, and pyroclastic deposits. Cenozoic map units reflect four major eruptive stages: Stage 1 (11-9 Ma: rhyolite and andesite), Stage 2 (9-7.5 Ma: dacite>basalt>andesite), Stage 3 (7-5 Ma: dacite>basalt), and Stage 4 (4.5-0.7 Ma: basalt). The predominant loci of eruptive centers migrated northwestward during this volcanic evolution, coeval with northwestward migration of adjacent depocenters. Stage 1 and 2 volcanism is broadly correlative to the supradetachment stage of rhombochasm development. Related intrusions include exposed upper-plate hypabyssal and lower-plate plutonic bodies. Stage 3 and 4 volcanism occurred during two tectonic stages in which higher-angle faults cut across the detachment fault, forming basins that are nested within the original detachment-floored area of the rhombochasm. Time-transgressive changes from dominantly silicic and intermediate magmas in Stages 1 and 2 to dominantly mafic and lesser intermediate magmas in Stages 3 and 4 coincided with decreases in eruptive

  6. Sulfur dioxide emissions related to volcanic activity at Asama volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ohwada, Michiko; Kazahaya, Kohei; Mori, Toshiya; Kazahaya, Ryunosuke; Hirabayashi, Jun-ichi; Miyashita, Makoto; Onizawa, Shin'ya; Mori, Takehiko

    2013-12-01

    A 40-year-long record of the sulfur dioxide (SO2) emission rate of Asama volcano, Japan, is presented including high-temporal-resolution data since the 2004 eruption. The 2004 and 2008-2009 eruptive activities were associated with high SO2 emission, and SO2 emission rates markedly fluctuated. In contrast, stable and weak SO2 emissions have been observed for the rest of the investigated interval. The fluctuation of the SO2 emission rates is correlated with the number of shallow low-frequency B-type earthquakes, implying that increased flows of gas and/or magma induced the B-type earthquakes along the shallow conduit. The total volumes of outgassed magma during the 2004 and 2008-2009 eruptive activities are estimated to be 1.9 × 108 and 1.5 × 108 m3, respectively. These volumes are about 100-200 times larger than those of the erupted magma, indicating that the large volumes of the magma were outgassed without being erupted (i.e., excess degassing/outgassing). Degassing and outgassing driven by magma convection rather than by permeable gas flow in the conduit is concluded as the probable degassing/outgassing process of Asama volcano based on model examinations, and is thought to occur regardless of the outgassing intensity. Production rates of outgassed magma related to the 2004 and 2008-2009 eruptive periods are estimated to have been 7.4 × 103 and 6.7 × 103 kg/s, respectively. These values are one order of magnitude higher than the average production rate of 0.92 × 103 kg/s for the inactive periods. Increased supply of fresh magma is thought to activate magma convection in the conduit and to thereby increase magma degassing/outgassing.

  7. The Pulse of the Volcano: Discovery of Episodic Activity at Prometheus on Io

    NASA Technical Reports Server (NTRS)

    Davies, A. G.

    2003-01-01

    The temporal behaviour of thermal output from a volcano yields valuable clues to the processes taking place at and beneath the surface. Galileo Near Infrared Mapping Spectrometer (NIMS) data show that the ionian volcanoes Prometheus and Amirani have significant thermal emission in excess of nonvolcanic background emission in every geometrically appropriate NIMS observation. The 5 micron brightness of these volcanoes shows considerable variation from orbit to orbit. Prometheus in particular exhibits an episodicity that yields valuable constraints to the mechanisms of magma supply and eruption. This work is part of an on-going study to chart and quantify the thermal emission of Io's volcanoes, determine mass eruption rates, and note eruption style.

  8. Icelandic Volcanoes Geohazard Supersite and FUTUREVOLC: role of interferometric synthetic aperture radar to identify renewed unrest and track magma movement beneath the most active volcanoes in Iceland

    NASA Astrophysics Data System (ADS)

    Parks, Michelle; Dumont, Stéphanie; Spaans, Karsten; Drouin, Vincent; Sigmundsson, Freysteinn; Hooper, Andrew; Michalczewska, Karolina; Ófeigsson, Benedikt

    2014-05-01

    FUTUREVOLC is an integrated volcano monitoring project, funded by the European Commission (FP7) and led by the University of Iceland and the Icelandic Meteorological Office (IMO). The project is a European collaborative effort, comprising 26 partners, aimed at integrating ground based and satellite observations for improved monitoring and evaluation of volcanic hazards. Iceland has also recently been declared a Geohazard Supersite by the Committee on Earth Observation Satellites, based on its propensity for relatively frequent eruptions and their potentially hazardous, long ranging effects. Generating a long-term time series of ground displacements is key to gaining a better understanding of sub-volcanic processes, including the detection of new melt and migration of magma within the crust. The focus of the FUTUREVOLC deformation team is to generate and interpret an extended time series of high resolution deformation measurements derived from InSAR observations, in the vicinity of the four most active volcanoes in Iceland: Grímsvötn, Katla, Hekla and Bárdarbunga. A comprehensive network of continuous deformation monitoring equipment, led by IMO and collaborators, is already deployed at these volcanoes, including GPS, tilt and borehole strainmeters. InSAR observations are complementary to field based measurements and their high spatial resolution assists in resolving the geometry and location of the source of the deformation. InSAR and tilt measurements at Hekla indicate renewed melt supply to a sub-volcanic reservoir after the last eruption in 2000. Recent deformation studies utilising data spanning this eruption, have provided insight into the shallow plumbing system which may explain the large reduction in eruption repose interval following the 1970 eruption. Although InSAR and GPS observations at Katla volcano (between 2001 and 2009) suggest no indication of magma induced deformation outside the ice-cap, it is possible that a small flood at Mýrdalsjökull in

  9. Broadband seismic monitoring of active volcanoes using deterministic and stochastic approaches

    NASA Astrophysics Data System (ADS)

    Kumagai, H.; Nakano, M.; Maeda, T.; Yepes, H.; Palacios, P.; Ruiz, M. C.; Arrais, S.; Vaca, M.; Molina, I.; Yamashina, T.

    2009-12-01

    We systematically used two approaches to analyze broadband seismic signals observed at active volcanoes: one is waveform inversion of very-long-period (VLP) signals in the frequency domain assuming possible source mechanisms; the other is a source location method of long-period (LP) and tremor using their amplitudes. The deterministic approach of the waveform inversion is useful to constrain the source mechanism and location, but is basically only applicable to VLP signals with periods longer than a few seconds. The source location method uses seismic amplitudes corrected for site amplifications and assumes isotropic radiation of S waves. This assumption of isotropic radiation is apparently inconsistent with the hypothesis of crack geometry at the LP source. Using the source location method, we estimated the best-fit source location of a VLP/LP event at Cotopaxi using a frequency band of 7-12 Hz and Q = 60. This location was close to the best-fit source location determined by waveform inversion of the VLP/LP event using a VLP band of 5-12.5 s. The waveform inversion indicated that a crack mechanism better explained the VLP signals than an isotropic mechanism. These results indicated that isotropic radiation is not inherent to the source and only appears at high frequencies. We also obtained a best-fit location of an explosion event at Tungurahua when using a frequency band of 5-10 Hz and Q = 60. This frequency band and Q value also yielded reasonable locations for the sources of tremor signals associated with lahars and pyroclastic flows at Tungurahua. The isotropic radiation assumption may be valid in a high frequency range in which the path effect caused by the scattering of seismic waves results in an isotropic radiation pattern of S waves. The source location method may be categorized as a stochastic approach based on the nature of scattering waves. We further applied the waveform inversion to VLP signals observed at only two stations during a volcanic crisis

  10. Active mud volcanoes on the continental slope of the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Caress, D. W.; Gwiazda, R.; Melling, H.; Riedel, M.; Jin, Y. K.; Hong, J. K.; Kim, Y.-G.; Graves, D.; Sherman, A.; Lundsten, E.; Anderson, K.; Lundsten, L.; Villinger, H.; Kopf, A.; Johnson, S. B.; Hughes Clarke, J.; Blasco, S.; Conway, K.; Neelands, P.; Thomas, H.; Côté, M.

    2015-09-01

    Morphologic features, 600-1100 m across and elevated up to 30 m above the surrounding seafloor, interpreted to be mud volcanoes were investigated on the continental slope in the Beaufort Sea in the Canadian Arctic. Sediment cores, detailed mapping with an autonomous underwater vehicle, and exploration with a remotely operated vehicle show that these are young and actively forming features experiencing ongoing eruptions. Biogenic methane and low-chloride, sodium-bicarbonate-rich waters are extruded with warm sediment that accumulates to form cones and low-relief circular plateaus. The chemical and isotopic compositions of the ascending water indicate that a mixture of meteoric water, seawater, and water from clay dehydration has played a significant role in the evolution of these fluids. The venting methane supports extensive siboglinid tubeworms communities and forms some gas hydrates within the near seafloor. We believe that these are the first documented living chemosynthetic biological communities in the continental slope of the western Arctic Ocean.

  11. Lightning and electrical activity during the Shiveluch volcano eruption on 16 November 2014

    NASA Astrophysics Data System (ADS)

    Shevtsov, Boris M.; Firstov, Pavel P.; Cherneva, Nina V.; Holzworth, Robert H.; Akbashev, Renat R.

    2016-03-01

    According to World Wide Lightning Location Network (WWLLN) data, a sequence of lightning discharges was detected which occurred in the area of the explosive eruption of Shiveluch volcano on 16 November 2014 in Kamchatka. Information on the ash cloud motion was confirmed by the measurements of atmospheric electricity, satellite observations and meteorological and seismic data. It was concluded that WWLLN resolution is enough to detect the earlier stage of volcanic explosive eruption when electrification processes develop the most intensively. The lightning method has the undeniable advantage for the fast remote sensing of volcanic electric activity anywhere in the world. There is a good opportunity for the development of WWLLN technology to observe explosive volcanic eruptions.

  12. Insights on Volcanic Activity - Self-Potential and Gravity surveys of Masaya volcano

    NASA Astrophysics Data System (ADS)

    Williams-Jones, G.; Mauri, G.; Saracco, G.

    2006-12-01

    For more than ten years, the activity of Masaya volcano, Nicaragua, has been surveyed annually in order to characterize the long term mass/density variations within the shallow magma chamber. However, the injection of new magma is a rapid process, requiring only several hours or days. Other cyclical short period phenomena may be present (e.g., hydrothermal systems) and responsible for noise in the measured signal during a typical dynamic gravity survey. In order to determine the origin and importance of this noise and fully characterize any short period variations, a continuous gravity survey was made from February 16, 2006 to March 12, 2006 in the summit crater of Masaya. During this period, a short term of gravity variation of 60 μGal was measured with a wavelength of 20 hours. Hydrothermal systems, which may or may not be well developed, are directly related to heat, gas and fluids coming from the shallow magma chamber and plumbing system. Others sources of fluids are rainfall and the local aquifer, notably at the caldera lake, Laguna Masaya. Movement of hydrothermal fluids, which will generate self-potential (SP) signals, are directly influenced by superficial dyke injection and fluctuations of magma in the shallow plumbing system. The depth and movement of large fluid cells can be localized by self- potential data when processed by continuous wavelet transform. To characterize the shape and position of the hydrothermal system on the Masaya volcano, several SP profiles were made in conjunction with the continuous gravity survey. The SP data from around the summit pit craters were processed by continuous wavelet transform to localize the main large cell of hydrothermal fluid and determine the effects of the hydrothermal fluids on the continuous gravity measurements. The combination of SP and continuous gravity can give insight into short and medium term variations in magmatic activity.

  13. Seismicity and eruptive activity at Fuego Volcano, Guatemala: February 1975 -January 1977

    USGS Publications Warehouse

    Yuan, A.T.E.; McNutt, S.R.; Harlow, D.H.

    1984-01-01

    We examine seismic and eruptive activity at Fuego Volcano (14??29???N, 90?? 53???W), a 3800-m-high stratovolcano located in the active volcanic arc of Guatemala. Eruptions at Fuego are typically short-lived vulcanian eruptions producing ash falls and ash flows of high-alumina basalt. From February 1975 to December 1976, five weak ash eruptions occurred, accompanied by small earthquake swarms. Between 0 and 140 (average ??? 10) A-type or high-frequency seismic events per day with M > 0.5 were recorded during this period. Estimated thermal energies for each eruption are greater by a factor of 106 than cumulative seismic energies, a larger ratio than that reported for other volcanoes. Over 4000 A-type events were recorded January 3-7, 1977 (cumulative seismic energy ??? 109 joules), yet no eruption occurred. Five 2-hour-long pulses of intense seismicity separated by 6-hour intervals of quiescence accounted for the majority of events. Maximum likelihood estimates of b-values range from 0.7 ?? 0.2 to 2.1 ?? 0.4 with systematically lower values corresponding to the five intense pulses. The low values suggest higher stress conditions. During the 1977 swarm, a tiltmeter located 6 km southeast of Fuego recorded a 14 ?? 3 microradian tilt event (down to SW). This value is too large to represent a simple change in the elastic strain field due to the earthquake swarm. We speculate that the earthquake swarm and tilt are indicative of subsurface magma movement. ?? 1984.

  14. How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

    NASA Astrophysics Data System (ADS)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Bagnardi, Marco; Acocella, Valerio

    2016-04-01

    Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we use numerical models to show that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Galápagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observation. We then develop a general model for the stress state at volcanic edifices with calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control the shallow accumulation of magma in stacked sills, consistently with observations as well as the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

  15. Characterization and interpretation of volcanic activity at Redoubt, Bezymianny and Karymsky volcanoes through direct and remote measurements of volcanic emissions

    NASA Astrophysics Data System (ADS)

    Lopez, Taryn M.

    Surface measurements of volcanic emissions can provide critical insight into subsurface processes at active volcanoes such as the influx or ascent of magma, changes in conduit permeability, and relative eruption size. In this dissertation I employ direct and remote measurements of volcanic emissions to characterize activity and elucidate subsurface processes at three active volcanoes around the North Pacific. The 2009 eruption of Redoubt Volcano, Alaska, produced elevated SO2 emissions that were detected by the Ozone Monitoring Instrument (OMI) satellite sensor for over three months. This provided a rare opportunity to characterize Redoubt's daily SO2 emissions and to validate the OMI measurements. Order of magnitude variations in daily SO2 mass were observed, with over half of the cumulative SO2 emissions released during the explosive phase of the eruption. Correlations among OMI daily SO2 mass, tephra mass and acoustic energies during the explosive phase suggest that OMI data may be used to infer eruption size and explosivity. From 2007 through 2010 direct and remote measurements of volcanic gas composition and flux were measured at Bezymianny Volcano, Kamchatka, Russia. During this period Bezymianny underwent five explosive eruptions. Estimates of passive and eruptive SO2 emissions suggest that the majority of SO2 is released passively. Order of magnitude variations in total volatile flux observed throughout the study period were attributed to changes in the depth of gas exsolution and separation from the melt at the time of sample collection. These findings suggest that exsolved gas composition may be used to detect magma ascent prior to eruption at Bezymianny Volcano. Karymsky Volcano, Kamchatka, Russia, is a dynamic volcano which exhibited four end-member activity types during field campaigns in 2011 and 2012, including: discrete ash explosions, pulsatory degassing, gas jetting, and explosive eruption. These activity types were characterized quantitatively

  16. International Volcanological Field School in Kamchatka and Alaska: Experiencing Language, Culture, Environment, and Active Volcanoes

    NASA Astrophysics Data System (ADS)

    Eichelberger, J. C.; Gordeev, E.; Ivanov, B.; Izbekov, P.; Kasahara, M.; Melnikov, D.; Selyangin, O.; Vesna, Y.

    2003-12-01

    The Kamchatka State University of Education, University of Alaska Fairbanks, and Hokkaido University are developing an international field school focused on explosive volcanism of the North Pacific. An experimental first session was held on Mutnovsky and Gorely Volcanoes in Kamchatka during August 2003. Objectives of the school are to:(1) Acquaint students with the chemical and physical processes of explosive volcanism, through first-hand experience with some of the most spectacular volcanic features on Earth; (2) Expose students to different concepts and approaches to volcanology; (3) Expand students' ability to function in a harsh environment and to bridge barriers in language and culture; (4) Build long-lasting collaborations in research among students and in teaching and research among faculty in the North Pacific region. Both undergraduate and graduate students from Russia, the United States, and Japan participated. The school was based at a mountain hut situated between Gorely and Mutnovsky Volcanoes and accessible by all-terrain truck. Day trips were conducted to summit craters of both volcanoes, flank lava flows, fumarole fields, ignimbrite exposures, and a geothermal area and power plant. During the evenings and on days of bad weather, the school faculty conducted lectures on various topics of volcanology in either Russian or English, with translation. Although subjects were taught at the undergraduate level, lectures led to further discussion with more advanced students. Graduate students participated by describing their research activities to the undergraduates. A final session at a geophysical field station permitted demonstration of instrumentation and presentations requiring sophisticated graphics in more comfortable surroundings. Plans are underway to make this school an annual offering for academic credit in the Valley of Ten Thousand Smokes, Alaska and in Kamchatka. The course will be targeted at undergraduates with a strong interest in and

  17. Array analyses of volcanic earthquakes and tremor recorded at Las Cañadas caldera (Tenerife Island, Spain) during the 2004 seismic activation of Teide volcano

    NASA Astrophysics Data System (ADS)

    Almendros, Javier; Ibáñez, Jesús M.; Carmona, Enrique; Zandomeneghi, Daria

    2007-02-01

    We analyze data from three seismic antennas deployed in Las Cañadas caldera (Tenerife) during May-July 2004. The period selected for the analysis (May 12-31, 2004) constitutes one of the most active seismic episodes reported in the area, except for the precursory seismicity accompanying historical eruptions. Most seismic signals recorded by the antennas were volcano-tectonic (VT) earthquakes. They usually exhibited low magnitudes, although some of them were large enough to be felt at nearby villages. A few long-period (LP) events, generally associated with the presence of volcanic fluids in the medium, were also detected. Furthermore, we detected the appearance of a continuous tremor that started on May 18 and lasted for several weeks, at least until the end of the recording period. It is the first time that volcanic tremor has been reported at Teide volcano. This tremor was a small-amplitude, narrow-band signal with central frequency in the range 1-6 Hz. It was detected at the three antennas located in Las Cañadas caldera. We applied the zero-lag cross-correlation (ZLCC) method to estimate the propagation parameters (back-azimuth and apparent slowness) of the recorded signals. For VT earthquakes, we also determined the S-P times and source locations. Our results indicate that at the beginning of the analyzed period most earthquakes clustered in a deep volume below the northwest flank of Teide volcano. The similarity of the propagation parameters obtained for LP events and these early VT earthquakes suggests that LP events might also originate within the source volume of the VT cluster. During the last two weeks of May, VT earthquakes were generally shallower, and spread all over Las Cañadas caldera. Finally, the analysis of the tremor wavefield points to the presence of multiple, low-energy sources acting simultaneously. We propose a model to explain the pattern of seismicity observed at Teide volcano. The process started in early April with a deep magma

  18. Geological and petrological evidences for mingling and mixing of magmas in the Me-akan and Taisetsu volcanoes, eastern and central Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Wada, Keiji; Sato, Eiichi; Anzai, Keisuke; Baba, Hikaru

    2015-04-01

    Both the Me-akan volcano, eastern Hokkaido, and the Taisetsu volcano, central Hokkaido, are exactly the clear fields showing geological evidences for magma mingling and magma mixing, such as coexistence of basaltic andesite scoria and dacite pumice in plinian fall deposit, heterogeneous juvenile ejecta (banded pumice, etc.) in pyroclastic flow, mafic inclusions in lavas, and banded structure in lavas. Throughout the eruption history of Me-Akan volcano, the largest eruptions occurred about 12000-13000 years ago. The main eruptions of this stage were continuously eruptive sequence of pumice-scoria pyroclastic flows and pumice-scoria plinian fallout, which show the multi-stage processes of magma mixing and mingling in the magma plumbing system through mineralogical and petrological analyses of the juvenile products. Each deposit contains pumice (SiO2=63wt.%), scoria (SiO2=55wt.%) and heterogeneous scoria. The core composition of plagioclase phenocrysts of these scoria and pumice shows a same bimodal distribution of low-An plagioclase (An=59) and high-An plagioclase (An>70). These indicate that heterogeneous ejecta such as banded pumice were exactly mingling products of both mixed mafic and felsic magmas, which were derived from continuous magma mixing of felsic and mafic end-member magmas in a zoned magma chamber. The lavas in Taisetsu volcano frequently show the banded structure of andesite and dacite magmas, and are characterized by containing a number of mafic inclusions with coarse- and fine-grained types. These inclusions were originated from two kinds of mafic end-member magmas and have different resident times in magma chamber. Some coarse-type inclusion was probably brought out from dacite crystal mush layer. The plagioclase phenocrysts in the host lava show trimodal An-content distributions (

  19. Organic geochemical signatures controlling methane outgassing at active mud volcanoes in the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    DongHun, Lee; YoungKeun, Jin; JungHyun, Kim; Heldge, Niemann; JongKu, Gal; BoHyung, Choi

    2016-04-01

    Based on the water column acoustic anomalies related to active methane (CH4) venting, numerous active Mud Volcanoes (MVs) were recently identified at ~282, ~420, and ~740 m water depths on the continental slope of the Canadian Beaufort Sea (Paull et al., 2015). While geophysical aspects such as the multibeam bathymetric mapping are thoroughly investigated, biogeochemical processes controlling outgassing CH4 at the active MVs are not well constrained. Here, we investigated three sediment cores from the active MVs and one sediment core from a non-methane influenced reference site recovered during the ARA-05C expedition with the R/V ARAON in 2014. We analyzed lipid biomarkers and their stable carbon isotopic values (δ13C) in order to determine key biogeochemical processes involved in CH4 cycling in the MV sediments. Downcore CH4 and sulphate (SO42-) concentration measurements revealed a distinct sulfate-methane transition zone (SMTZ) at the shallow sections of the cores (15 - 45 cm below seafloor (cm bsf) at 282 m MV, 420 m MV, and 740 m MV). The most abundant diagnostic lipid biomarkers in the SMTZ were sn-2-hydroxyarchaeol (-94‰) and archaeol (-66‰) with the sn-2-hydroxyarchaeol: archaeol ratio of 1.1 to 5, indicating the presence of ANME-2 or -3. However, we also found substantial amounts of monocyclic biphytane-1 (BP-1, -118‰), which is rather indicative for ANME-1. Nevertheless, the concentration of sn-2-hydroxyarchaeol was 2-fold higher than any other archaeal lipids, suggesting a predominant ANME-2 or -3 rather than ANME-1 as a driving force for the anaerobic methane oxidation (AOM) in these systems. We will further investigate the microbial community at the active MVs using nucleic acid (RNA and DNA) sequence analyses in near future. Our study provides first biogeochemical data set of the active MVs in the Canadian Beaufort Sea, which helps to better understand CH4 cycling mediated in these systems. Reference Paull, C.K., et al. (2015), Active mud

  20. Hydrodynamic modeling of magmatic-hydrothermal activity at submarine arc volcanoes, with implications for ore formation

    NASA Astrophysics Data System (ADS)

    Gruen, Gillian; Weis, Philipp; Driesner, Thomas; Heinrich, Christoph A.; de Ronde, Cornel E. J.

    2014-10-01

    Subduction-related magmas have higher volatile contents than mid-ocean ridge basalts, which affects the dynamics of associated submarine hydrothermal systems. Interaction of saline magmatic fluids with convecting seawater may enhance ore metal deposition near the seafloor, making active submarine arcs a preferred modern analogue for understanding ancient massive sulfide deposits. We have constructed a quantitative hydrological model for sub-seafloor fluid flow based on observations at Brothers volcano, southern Kermadec arc, New Zealand. Numerical simulations of multi-phase hydrosaline fluid flow were performed on a two-dimensional cross-section cutting through the NW Caldera and the Upper Cone sites, two regions of active venting at the Brothers volcanic edifice, with the former hosting sulfide mineralization. Our aim is to explore the flow paths of saline magmatic fluids released from a crystallizing magma body at depth and their interaction with seawater circulating through the crust. The model includes a 3×2 km sized magma chamber emplaced at ∼2.5 km beneath the seafloor connected to the permeable cone via a ∼200 m wide feeder dike. During the simulation, a magmatic fluid was temporarily injected from the top of the cooling magma chamber into the overlying convection system, assuming hydrostatic conditions and a static permeability distribution. The simulations predict a succession of hydrologic regimes in the subsurface of Brothers volcano, which can explain some of the present-day hydrothermal observations. We find that sub-seafloor phase separation, inferred from observed vent fluid salinities, and the temperatures of venting at Brothers volcano can only be achieved by input of a saline magmatic fluid at depth, consistent with chemical and isotopic data. In general, our simulations show that the transport of heat, water, and salt from magmatic and seawater sources is partly decoupled. Expulsion of magmatic heat and volatiles occurs within the first few

  1. Linking observations at active volcanoes to physical processes through conduit flow modelling

    NASA Astrophysics Data System (ADS)

    Thomas, Mark; Neuberg, Jurgen

    2010-05-01

    Low frequency seismic events observed on volcanoes such as Soufriere hills, Montserrat may offer key indications about the state of a volcanic system. To obtain a better understanding of the source of these events and of the physical processes that take place within a volcano it is necessary to understand the conditions of magma a depth. This can be achieved through conduit flow modelling (Collier & Neuberg, 2006). 2-D compressible Navier-Stokes equations are solved through a Finite Element approach, for differing initial water and crystal contents, magma temperatures, chamber overpressures and geometric shapes of conduit. In the fully interdependent modelled system each of these variables has an effect on the magma density, viscosity, gas content, and also the pressure within the flow. These variables in turn affect the magma ascent velocity and the overall eruption dynamics of an active system. Of particular interest are the changes engendered in the flow by relativity small variations in the conduit geometry. These changes can have a profound local effect of the ascent velocity of the magma. By restricting the width of 15m wide, 5000m long vertical conduit over a 100m distance a significant acceleration of the magma is seen in this area. This has implications for the generation of Low-Frequency (LF) events at volcanic systems. The strain-induced fracture of viscoelastic magma or brittle failure of melt has been previously discussed as a possible source of LF events by several authors (e.g. Tuffen et al., 2003; Neuberg et al., 2006). The location of such brittle failure however has been seen to occur at relativity shallow depths (<1000m), which does not agree with the location of recorded LF events. By varying the geometry of the conduit and causing accelerations in the magma flow, localised increases in the shear strain rate of up to 30% are observed. This provides a mechanism of increasing the depth over witch brittle failure of melt may occur. A key observable

  2. Investigating the active hydrothermal field of Kolumbo Volcano using CTD profiling

    NASA Astrophysics Data System (ADS)

    Eleni Christopoulou, Maria; Mertzimekis, Theo; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Carey, Steve

    2014-05-01

    The submarine Kolumbo volcano NE of Santorini Island and the unique active hydrothermal vent field on its crater field (depth ~ 500 m) have been recently explored in multiple cruises aboard E/V Nautilus. ROV explorations showed the existence of extensive vent activity and almost completely absence of vent-specific macrofauna. Gas discharges have been found to be 99%-rich in CO2, which is sequestered at the bottom of the crater due to a special combination of physicochemical and geomorphological factors. The dynamic conditions existing along the water column in the crater have been studied in detail by means of temperature, salinity and conductivity depth profiles for the first time. CTD sensors aboard the ROV Hercules were employed to record anomalies in those parameters in an attempt to investigate several active and inactive vent locations. Temporal CTD monitoring inside and outside of the crater was carried out over a period of two years. Direct comparison between the vent field and locations outside the main cone, where no hydrothermal activity is known to exist, showed completely different characteristics. CTD profiles above the active vent field (NNE side) are correlated to Kolumbo's cone morphology. The profiles suggest the existence of four distinct zones of physicochemical properties in the water column. The layer directly above the chimneys exhibit gas discharges highly enriched in CO2. Continuous gas motoring is essential to identify the onset of geological hazards in the region.

  3. A Wireless Seismoacoustic Sensor Network for Monitoring Activity at Volcano Reventador, Ecuador

    NASA Astrophysics Data System (ADS)

    Welsh, M.; Werner-Allen, G.; Lorincz, K.; Marcillo, O.; Ruiz, M.; Johnson, J.; Lees, J. M.

    2005-12-01

    We developed a wireless sensor network for monitoring seismoacoustic activity at Volcano Reventador, Ecuador. Wireless sensor networks are a new technology and our group is among the first to apply them to monitoring volcanoes. The small size, low power, and wireless communication capabilities can greatly simplify deployments of large sensor arrays. The network consisted of 16 wireless sensor nodes, each outfitted with an 8 MHz CPU (TI MSP430) and a 2.4 GHz IEEE 802.15.4 radio (Chipcon CC2420) with data rates up to 80 Kbps. Each node acquired acoustic and seismic data at 24-bit resolution, with a microphone and either a single-axis geophone or triaxial short-period seismometer. Each node is powered by two D-cell batteries with a lifetime of about 1 week, and measures 18 x 10 x 8 cm. Nodes were distributed radially from the vent over a 3 km aperture. Control and data messages are relayed via radio to a base station node, with inter-node distances of up to 420 m. The base station transmits data using a FreeWave radio modem, via a repeater, to a laptop located 4 km from the deployment site. Each node samples continuous sensor data and a simple event-detection algorithm is used to trigger data collection. When a sensor detects an event, it relays a short message to the base station via radio. If several nodes report an event within a short time interval, the last 60 seconds of data is downloaded from each node in turn. One of the sensor nodes is programmed to transmit continuous data; due to limited radio bandwidth, it is not possible to collect continuous data from all nodes in the array. A GPS receiver and time synchronization protocol is used to establish a global timebase across all sensor nodes.

  4. Volcano-hydrothermal activity detected by precise levelling surveys at the Tatun volcano group in Northern Taiwan during 2006-2013

    NASA Astrophysics Data System (ADS)

    Murase, Masayuki; Lin, Cheng-Hong; Kimata, Fumiaki; Mori, Hitoshi; Pu, Hsin-Chieh

    2014-10-01

    Precise levelling surveys were conducted from 2006 to 2013 on three levelling routes in the Tatun volcano group (TVG) located approximately 15 km northeast of Taipei, to detect deformation in relation to the volcano-hydrothermal activities of the TVG. Uplift was detected around the most active fumarole, Tayoukeng fumarole, throughout the period 2007 to 2011; the uplift rate throughout the period from March 2009 to March 2011 was reduced in comparison to the rate between 2007 and 2009. Following this, a dormant state or a small amount of subsidence was detected in the period March 2011 to March 2013. And throughout the period from June 2006 to March 2013, subsidence was centred on an area 0.5 km east of the summit of Mt. Cising, the highest peak in the TVG. A model of two spherical sources was therefore estimated from the deformation recorded from August 2007 to March 2011, using a genetic algorithm. A deflation source was obtained about 0.5 km northeast of Mt. Cising at a depth of 2 km; and an inflation source was situated approximately 1 km south of the Tayoukeng fumarole at a depth of 0.7 km. Based on previous seismic and AMT studies, the estimated sources are interpreted as being hydrothermal reservoirs. Because almost all the benchmarks around Mt. Cising show subsidence at a constant speed, we conclude that the deeper hydrothermal reservoir at a depth of 2 km may have been releasing hydrothermal fluid at a constant rate throughout the period from 2006 to 2013. However, it was suggested that in 2011 the shallower hydrothermal reservoir at a depth of 0.7 km changed from an inflation state to a dormant state (or small deflation) based on temporal vertical changes around Tayoukeng fumarole. A possible model for the volcano-hydrothermal system is therefore proposed. It is considered that the hydrothermal fluid may be supplied intermittently from the magma chamber to the deeper hydrothermal reservoir at a depth of 2 km (although this type of fluid input event may not

  5. Nicaraguan Volcanoes

    Atmospheric Science Data Center

    2013-04-18

    article title:  Nicaraguan Volcanoes     View Larger Image Nicaraguan volcanoes, February 26, 2000 . The true-color image at left is a ... February 26, 2000 - Plumes from the San Cristobal and Masaya volcanoes. project:  MISR category:  gallery ...

  6. Cotopaxi volcano's unrest and eruptive activity in 2015: mild awakening after 73 years of quiescence

    NASA Astrophysics Data System (ADS)

    Hidalgo, Silvana; Bernard, Benjamin; Battaglia, Jean; Gaunt, Elizabeth; Barrington, Charlotte; Andrade, Daniel; Ramón, Patricio; Arellano, Santiago; Yepes, Hugo; Proaño, Antonio; Almeida, Stefanie; Sierra, Daniel; Dinger, Florian; Kelly, Peter; Parra, René; Bobrowski, Nicole; Galle, Bo; Almeida, Marco; Mothes, Patricia; Alvarado, Alexandra

    2016-04-01

    Cotopaxi volcano (5,897 m) is located 50 km south of Quito, the capital of Ecuador. The most dangerous hazards of this volcano are the devastating lahars that can be generated by the melting of its ice cap during pyroclastic flow-forming eruptions. The first seismic station was installed in 1976. Cotopaxi has been monitored by the Instituto Geofísico (Escuela Politécnica Nacional) since 1983. Presently the monitoring network is comprised of 11 broadband and 5 short period seismometers, 4 scanning DOAS, 1 infrared and 5 visible cameras, 7 DGPS, 5 tiltmeters, 11 AFM (lahar detectors) and a network of ashmeters. Due to the recent unrest, the monitoring of the volcano has been complemented by campaign airborne Multi-GAS and thermal IR measurements and ground-based mobile DOAS and stationary solar FTIR. After 73 years of quiescence, the first sign of unrest was a progressive increase in the amplitude of transient seismic events in April 2015. Since May 20, an increase in SO2 emissions from ˜500 t/d to ˜3 kt/day was detected followed by the appearance of seismic tremor on June 4. Both SO2 emissions of up to 5 kt/day and seismic tremor were observed until August 14 when a swarm of volcano-tectonic earthquakes preceded the first phreatic explosions. These explosions produced ash and gas columns reaching up to 9 km above the crater. The ash fall produced by the opening phase covered over 500 km2 with a submillimetric deposit corresponding to a mass of 1.65E+8 kg (VEI 1). During this period of explosions, SO2 emission rates up to 24 kt/day were observed, the highest thus far. The ash was dominantly hydrothermally altered and oxidized lithic fragments, hydrothermal minerals (alunite, gypsum), free crystals of plagioclase and pyroxenes, and little juvenile material. Unrest continued after August 14, with three episodes of ash emission. However, the intensity of ash fallout, average seismic amplitude, and SO2 emissions during each successive episode progressively decreased

  7. Physical volcanology of the submarine Mariana and Volcano Arcs

    NASA Astrophysics Data System (ADS)

    Bloomer, Sherman H.; Stern, Robert J.; Smoot, N. Christian

    1989-05-01

    Narrow-beam maps, selected dredge samplings, and surveys of the Mariana and Volcano Arcs identify 42 submarine volcanos. Observed activity and sample characteristics indicate 22 of these to be active or dormant. Edifices in the Volcano Arc are larger than most of the Mariana Arc edifices, more irregularly shaped with numerous subsidiary cones, and regularly spaced at 50 70 km. Volcanos in the Mariana Arc tend to be simple cones. Sets of individual cones and volcanic ridges are elongate parallel to the trend of the arc or at 110° counterclockwise from that trend, suggesting a strong fault control on the distribution of arc magmas. Volcanos in the Mariana Arc are generally developed west of the frontal arc ridge, on rifted frontal arc crust or new back-arc basin crust. Volcanos in the central Mariana Arc are usually subaerial, large (> 500 km3), and spaced about 50 70 km apart. Those in the northern and southern Marianas are largely submarine, closer together, and generally less than 500 km3 in volume. There is a shoaling of the arc basement around Iwo Jima, accompanied by the appearance of incompatible-element enriched lavas with alkalic affinities. The larger volcanic edifices must reflect either a higher magma supply rate or a greater age for the larger volcanos. If the magma supply (estimated at 10 20 km3/km of arc per million years at 18° N) has been relatively constant along the Mariana Arc, we can infer a possible evolutionary sequence for arc volcanos from small, irregularly spaced edifices to large (over 1000 km3) edifices spaced at 50 70 km. The volcano distribution and basal depths are consistent with the hypothesis of back-arc propagation into the Volcano Arc.

  8. Imaging the magmatic system of Newberry Volcano using Joint active source and teleseismic tomography

    NASA Astrophysics Data System (ADS)

    Heath, Benjamin A.; Hooft, Emilie E. E.; Toomey, Douglas R.; Bezada, Maximiliano J.

    2015-12-01

    In this paper, we combine active and passive source P wave seismic data to tomographically image the magmatic system beneath Newberry Volcano, located east of the Cascade arc. By using both travel times from local active sources and delay times from teleseismic earthquakes recorded on closely spaced seismometers (300-800 m), we significantly improve recovery of upper crustal velocity structure (<10 km depth). The tomographic model reveals a low-velocity feature between 3 and 5 km depth that lies beneath the caldera, consistent with a magma body. In contrast to earlier tomographic studies, where elevated temperatures were sufficient to explain the recovered low velocities, the larger amplitude low-velocity anomalies in our joint tomography model require low degrees of partial melt (˜10%), and a minimum melt volume of ˜2.5 km3. Furthermore, synthetic tests suggest that even greater magnitude low-velocity anomalies, and by inference larger volumes of magma (up to 8 km3), are needed to explain the observed waveform variability. The lateral extent and shape of the inferred magma body indicates that the extensional tectonic regime at Newberry influences the emplacement of magmatic intrusions. Our study shows that jointly inverting active source and passive source seismic data improves tomographic imaging of the shallow crustal seismic structure of volcanic systems and that active source experiments would benefit from longer deployment times to also record teleseismic sources.

  9. A synthesis of the recent activity of Galeras volcano, Colombia: Seven years of continuous surveillance, 1989 1995

    NASA Astrophysics Data System (ADS)

    Cortés J, Gloria Patricia; Raigosa A, Jaime

    1997-05-01

    The current period of re-activation since 1988 at Galeras volcano, Colombia, has been characterized mainly by the following events: (1) a semi-continuous series of Vulcanian eruptions during 5-9 May 1989; (2) emplacement of an andesitic lava dome at the bottom of the main crater in October-November 1991; (3) six vulcanian eruptions during 1992-1993, the first of which destroyed most of the dome on 16 July 1992; and (4) three volcano-tectonic seismic crises in April 1993, November-December 1993 and March 1995. During much of this seven-year period, several small ash and gas emissions also have taken place. The 4-9 May 1989 eruptions originated from the secondary crater El Pinta and deposited ash, lapilli and blocks in the crater area. The 1992-1993 eruptions originated from the main crater and were associated with obstruction of the conduit by magma from dome emplacement in late 1991, causing overpressurization of the system. For the 1992-1993 eruptions, pre-eruptive seismicity, deformation and SO 2 flux all exhibited very low levels. The eruptions were characterized by their sudden initiation, low intensity (VEI = 1), small eruption columns, and small volumes of erupted material. The source of the volcano-tectonic seismic crises is located approximately 3 km north and northeast of the crater. Some of these events were felt in Pasto and other towns located around the volcano, on one occasion causing loss of life, injuries and damage to buildings.

  10. A Fluorescein Tracer Release Experiment in the Hydrothermally Active Crater of Vailulu'u Volcano, Samoa

    NASA Astrophysics Data System (ADS)

    Hart, S. R.; Staudigel, H.; Workman, R.; Koppers, A.; Girard, A.

    2001-12-01

    Vailulu'u (Rockne) volcano marks the active end of the Samoa hotspot chain. The volcano is 4400 meters high, with a summit crater 2000 meters wide by 400 meters deep and summit peaks reaching to within 600 meters of the sea surface. The crater is hydrothermally active, as witnessed by intense particulate concentrations in the water column (values to 1.4 NTU's), a particulate smog ``halo'' surrounding the summit and extending out many kilometers, high Mn concentrations and 3He/4He ratios (values to 3.8 ppb and 8.6 Ra, respectively), and bottom-water temperature anomalies of 0.5oC. Basalts from the crater have been dated in the range 5-50 years, and likely reflect eruptions associated with a 1995 earthquake swarm. On April 3, 2001, we released a 20 kg point-source charge of fluorescein dye 30 meters above the 975m deep crater floor. The dye was dissolved in a 180 liter mixture of propanol and water, adjusted to a density 1.3 per mil heavier than the ambient water at the release depth. Released from a rubberized bag by means of a galvanic link. First detection of the released dye was 39 hours after the deployment; the dye was in a 50 meter thick layer, with a concentration peak at 900 meters (relative to the release depth of 945m). Tracking was carried out by a CTD-based fluorometer operated in tow-yo mode from the U.S.C.G. Icebreaker Polar Sea. The detection limit was 25 picograms/gram, and the maximum detected concentration was 18,000 pg/g (if evenly dispersed in the lower 150 meters of water in the crater, the expected concentration would be approx. 130 pg/g). While the dye pool was only surveyed for 4 days due to ship-transit constraints, significant horizontal and vertical dispersion was apparent. Vertical dispersion velocities were typically 0.05 cm/sec; horizontal velocities were typically higher by a factor of 10. An approximate diapycnal or eddy diffusivity, K, can be calculated from the rate of vertical spreading of the dye layer: K = Z2/2(t-t0), where Z is

  11. The heartbeat of the volcano: The discovery of episodic activity at Prometheus on Io

    USGS Publications Warehouse

    Davies, A.G.; Wilson, L.; Matson, D.; Leone, G.; Keszthelyi, L.; Jaeger, W.

    2006-01-01

    The temporal signature of thermal emission from a volcano is a valuable clue to the processes taking place both at and beneath the surface. The Galileo Near Infrared Mapping Spectrometer (NIMS) observed the volcano Prometheus, on the jovian moon Io, on multiple occasions between 1996 and 2002. The 5 micron (??m) brightness of this volcano shows considerable variation from orbit to orbit. Prometheus exhibits increases in thermal emission that indicate episodic (though non-periodic) effusive activity in a manner akin to the current Pu'u 'O'o-Kupaianaha (afterwards referred to as the Pu'u 'O'o) eruption of Kilauea, Hawai'i. The volume of material erupted during one Prometheus eruption episode (defined as the interval from minimum thermal emission to peak and back to minimum) from 6 November 1996 to 7 May 1997 is estimated to be ???0.8 km3, with a peak instantaneous volumetric flux (effusion rate) of ???140 m3 s-1, and an averaged volumetric flux (eruption rate) of ???49 m3 s-1. These quantities are used to model subsurface structure, magma storage and magma supply mechanisms, and likely magma chamber depth. Prometheus appears to be supplied by magma from a relatively shallow magma chamber, with a roof at a minimum depth of ???2-3 km and a maximum depth of ???14 km. This is a much shallower depth range than sources of supply proposed for explosive, possibly ultramafic, eruptions at Pillan and Tvashtar. As Prometheus-type effusive activity is widespread on Io, shallow magma chambers containing magma of basaltic or near-basaltic composition and density may be common. This analysis strengthens the analogy between Prometheus and Pu'u 'O'o, at least in terms of eruption style. Even though the style of eruption appears to be similar (effusive emplacement of thin, insulated, compound pahoehoe flows) the scale of activity at Prometheus greatly exceeds current activity at Pu'u 'O'o in terms of volume erupted, area covered, and magma flux. Whereas the estimated magma chamber at

  12. The heartbeat of the volcano: The discovery of episodic activity at Prometheus on Io

    NASA Astrophysics Data System (ADS)

    Davies, Ashley Gerard; Wilson, Lionel; Matson, Dennis; Leone, Giovanni; Keszthelyi, Laszlo; Jaeger, Windy

    2006-10-01

    The temporal signature of thermal emission from a volcano is a valuable clue to the processes taking place both at and beneath the surface. The Galileo Near Infrared Mapping Spectrometer (NIMS) observed the volcano Prometheus, on the jovian moon Io, on multiple occasions between 1996 and 2002. The 5 micron (μm) brightness of this volcano shows considerable variation from orbit to orbit. Prometheus exhibits increases in thermal emission that indicate episodic (though non-periodic) effusive activity in a manner akin to the current Pu'u 'O'o-Kupaianaha (afterwards referred to as the Pu'u 'O'o) eruption of Kilauea, Hawai'i. The volume of material erupted during one Prometheus eruption episode (defined as the interval from minimum thermal emission to peak and back to minimum) from 6 November 1996 to 7 May 1997 is estimated to be ˜0.8 km 3, with a peak instantaneous volumetric flux (effusion rate) of ˜140 m 3 s -1, and an averaged volumetric flux (eruption rate) of ˜49 m 3 s -1. These quantities are used to model subsurface structure, magma storage and magma supply mechanisms, and likely magma chamber depth. Prometheus appears to be supplied by magma from a relatively shallow magma chamber, with a roof at a minimum depth of ˜2-3 km and a maximum depth of ˜14 km. This is a much shallower depth range than sources of supply proposed for explosive, possibly ultramafic, eruptions at Pillan and Tvashtar. As Prometheus-type effusive activity is widespread on Io, shallow magma chambers containing magma of basaltic or near-basaltic composition and density may be common. This analysis strengthens the analogy between Prometheus and Pu'u 'O'o, at least in terms of eruption style. Even though the style of eruption appears to be similar (effusive emplacement of thin, insulated, compound pahoehoe flows) the scale of activity at Prometheus greatly exceeds current activity at Pu'u 'O'o in terms of volume erupted, area covered, and magma flux. Whereas the estimated magma chamber at

  13. Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska

    USGS Publications Warehouse

    Wallace, Kristi; Coombs, Michelle L.; Hayden, Leslie A.; Waythomas, Christopher F.

    2014-01-01

    Bluffs along the Hayes River valley, 31 km northeast and 40 km downstream from Hayes Volcano, reveal volcanic deposits that shed new light on its eruptive history. Three thick (>10 cm) and five thin (<10 cm) tephra-fall deposits are dacitic in whole rock composition and contain high proportions of amphibole to pyroxene and minor biotite and broadly correlate to Hayes tephra set H defined by earlier investigators. Two basal ages for the tephra-fall sequence of 3,690±30 and 3,750±30 14C yr B.P. are also consistent with the Hayes tephra set H timeframe. Distinguishing among Hayes tephra set H units is critical because the set is an important time-stratigraphic marker in south-central Alaska and this section provides a new reference section for Hayes tephra set H. Analysis of Fe-Ti oxide grains in the tephras shows promise for identifying individual Hayes deposits. Beneath the dacitic tephra sequence lies an older, poorly sorted tephra (tephra A) that contains dacite and rhyolite lapilli and whose basal age is 4,450±30 14C yr B.P. Immediately below the tephra-fall sequence (Unit III) lies a series of mass-flow deposits that are rich in rhyodacitic clasts (Unit II). Below Unit II and possibly coeval with it, is a 20–30 m thick pumiceous pyroclastic-flow deposit (Unit I) that extends to the valley floor. Here informally named the Hayes River ignimbrite, this deposit contains pumice clasts of rhyolite with quartz, sanidine, plagioclase, and biotite phenocrysts, an assemblage that is unique among known Quaternary volcanic products of Hayes and other Alaskan volcanoes. Units I, II, and tephra A of Unit III represent at least two previously unrecognized eruptions of Hayes Volcano that occurred prior to ~3,700 yr B.P. No compositionally equivalent distal tephra deposits correlative with Hayes Volcano rhyodacites or rhyolites have yet been identified, perhaps indicating that some of these deposits are pre-Holocene, and were largely removed by glacial ice during the last

  14. Geodynamic interpretations of plate subduction in the northernmost part of the Central Volcanic Zone from the geochemical evolution and quantification of the crustal contamination of the Nevado Solimana volcano, southern Peru

    NASA Astrophysics Data System (ADS)

    Vatin-Pérignon, Nicole; Oliver, Richard A.; Goemans, Pierre; Keller, Francine; Briqueu, Louis; Guido Salas, A.

    1992-04-01

    The northernmost volcanoes of the Central Volcanic Zone (CVZ, southern Peru) form three isolated composite centres along the western side of the active arc segment. This particular situation is comparable to the Chilean volcanic region at the southernmost end of the CVZ; in both cases, volcanoes lie close to the discontinuity where the Benioff zone becomes less steeply inclined and where crustal thickness decreases. The Solimana volcano (15°25'S), the oldest of the northerly eruptive centres, is built upon a Late Precambrian/Palaeozoic basement intruded by an Upper Cretaceous granite and unconformably overlain by Cenozoic volcanics. After a mid-Miocene andesitic activity along N10° regional faults, the Solimana volcanic history ranged from 4 Ma to Recent and built a composite andesite/dacite centre which consists of two units, preand post-caldera collapses and a youngest intra-caldera basaltic andesite phreatomagmatic activity. Fumaroles with thermal hot springs and precipitates indicate continuing activity of this volcano. North of 16°S, other adjacent volcanoes show the same evolution. Mineral chemistry and geochemical variations of the Solimana series are similar to those obtained from most high-K CVZ lavas and are largely consistent with fractionation processes. A restricted range of compositions of phenocryst assemblages, together with trace element data showing prominent LIL element enrichments relative to HFS element depletions, are typical of subduction-related continental arc magmas. However, this localized volcanism in the vicinity of the Nazca ridge-continent collision shows specific signatures: a weakly positive correlation between 87Sr/ 86Sr and Rb/Sr ratios, a high Ba and Sr content of basaltic andesites and both low ɛ Nd (- 2 to - 4) and high ɛSr (+16 to +21) values show differences north of 16°S from those to the south and suggest that distinct processes have controlled this environment. High Ba values for the most primitive lavas may be

  15. Seismic body wave separation in volcano-tectonic activity inferred by the Convolutive Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Capuano, Paolo; De Lauro, Enza; De Martino, Salvatore; Falanga, Mariarosaria; Petrosino, Simona

    2015-04-01

    One of the main challenge in volcano-seismological literature is to locate and characterize the source of volcano/tectonic seismic activity. This passes through the identification at least of the onset of the main phases, i.e. the body waves. Many efforts have been made to solve the problem of a clear separation of P and S phases both from a theoretical point of view and developing numerical algorithms suitable for specific cases (see, e.g., Küperkoch et al., 2012). Recently, a robust automatic procedure has been implemented for extracting the prominent seismic waveforms from continuously recorded signals and thus allowing for picking the main phases. The intuitive notion of maximum non-gaussianity is achieved adopting techniques which involve higher-order statistics in frequency domain., i.e, the Convolutive Independent Component Analysis (CICA). This technique is successful in the case of the blind source separation of convolutive mixtures. In seismological framework, indeed, seismic signals are thought as the convolution of a source function with path, site and the instrument response. In addition, time-delayed versions of the same source exist, due to multipath propagation typically caused by reverberations from some obstacle. In this work, we focus on the Volcano Tectonic (VT) activity at Campi Flegrei Caldera (Italy) during the 2006 ground uplift (Ciaramella et al., 2011). The activity was characterized approximately by 300 low-magnitude VT earthquakes (Md < 2; for the definition of duration magnitude, see Petrosino et al. 2008). Most of them were concentrated in distinct seismic sequences with hypocenters mainly clustered beneath the Solfatara-Accademia area, at depths ranging between 1 and 4 km b.s.l.. The obtained results show the clear separation of P and S phases: the technique not only allows the identification of the S-P time delay giving the timing of both phases but also provides the independent waveforms of the P and S phases. This is an enormous

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

    NASA Astrophysics Data System (ADS)

    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.

  17. The mechanics and three-dimensional internal structure of active magmatic systems: Kilauea volcano, Hawaii.

    USGS Publications Warehouse

    Ryan, M.P.

    1988-01-01

    Interpretation of abundant seismic data suggest that Kilauea's primary conduit within the upper mantle is concentrically zoned to about 34-km depth. This zoned structure is inferred to contain a central core region of relatively higher permeability, surrounded by numerous dikes that are in intermittent hydraulic communication with each other and with the central core. During periods of relatively high magma transport, the entire cross section of the conduit is utilized. During periods of relatively low to moderate transport, however, only the central core is active.-from Author

  18. Subsurface mass migration at active volcanoes: what we learnt from the VOLUME project

    NASA Astrophysics Data System (ADS)

    Saccorotti, G.; Volume Team

    2009-04-01

    Movements of multiphase fluids beneath active volcanoes are generally detected at the surface in terms of changes in geophysical and geochemical observables. The prompt detection and interpretation of such signals thus represent a crucial step toward the short-term evaluation of volcanic hazard. Funded through the European 6th framework program, the VOLUME project joined 19 institutions from 6 EU and 5 extra-european countries under the common goal of improving our understanding of how subsurface mass movement manifests itself at the surface, in turn revealing the significance of such movements as precursors to impending eruptions. We integrated high-end experimental procedures with a robust modeling framework to address some of the most relevant issues of modern, quantitative volcanology. In particular, our studies focused on: (i) Unrevealing the complex interplay between hydrothermal and magmatic fluids in generating the observed geophysical / geochemical signals, (ii) Detailing the location, geometry and dynamics of magma pathways and storage zones (iii) Probing variations of the elastic parameters of volcanic media in response to stress changes induced by mass migration, and (iv) Developing a robust computational framework for forward-modelling the geophysical observables resulting from the dynamics of multiphase magmatic systems. VOLUME activities developed at both european and extra-european volcanoes. We present here the most striking results obtained at two italian test-sites, namely Etna and Campi Flegrei, for which we had available data sets of unprecedented sensitivity and temporal resolution. Results from Etna include a) mapping of the shallow plumbing system from Moment-Tensor inversion of broadband seismic signal, b) the detection of deep magma intrusion from inversion of joint gravity-tremor anomalies; c) the measurement of changes in both elastic anisotropy and seismic velocity concomitant to the waning stage of the 2002 NE flank lava effusion; and

  19. Emission of gas and atmospheric dispersion of SO2 during the December 2013 eruption at San Miguel volcano (El Salvador, Central America)

    NASA Astrophysics Data System (ADS)

    Granieri, Domenico; Salerno, Giuseppe; Liuzzo, Marco; La Spina, Alessandro; Giuffrida, Giovanni; Caltabiano, Tommaso; Giudice, Gaetano; Gutierrez, Eduardo; Montalvo, Francisco; Burton, Michael R.; Papale, Paolo

    2015-07-01

    San Miguel volcano, El Salvador, erupted on 29 December 2013, after a 46 year period characterized by weak activity. Prior to the eruption a trend of increasing SO2 emission rate was observed, with all values measured after mid-November greater than the average value of the previous year (~310 t d-1). During the eruption, SO2 emissions increased from the level of ~330 t d-1 to 2200 t d-1, dropping after the eruption to an average level of 680 t d-1. Wind measurements and SO2 emission rates during the preeruptive, syneruptive, and posteruptive stages were used to model SO2 dispersion around the volcano. Atmospheric SO2 concentration exceeded the dangerous threshold of 5 ppm in the crater region and in some sectors with medium elevation of the highly visited volcanic cone. Combining the SO2 emission rate with measured CO2/SO2, HCl/SO2, and HF/SO2 plume gas ratios, we estimate the CO2, HCl, and HF outputs for the first time on this volcano.

  20. Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan

    PubMed Central

    Uyeda, S.; Hayakawa, M.; Nagao, T.; Molchanov, O.; Hattori, K.; Orihara, Y.; Gotoh, K.; Akinaga, Y.; Tanaka, H.

    2002-01-01

    Significant anomalous changes in the ultra low frequency range (≈0.01 Hz) were observed in both geoelectric and geomagnetic fields before the major volcano-seismic activity in the Izu Island region, Japan. The spectral intensity of the geoelectric potential difference between some electrodes on Niijima Island and the third principal component of geomagnetic field variations at an array network in Izu Peninsula started to increase from a few months before the onset of the volcano-seismic activity, culminating immediately before nearby magnitude 6 class earthquakes. Appearance of similar changes in two different measurements conducted at two far apart sites seems to provide information supporting the reality of preseismic electromagnetic signals. PMID:12032286

  1. Nyiragonga Volcano

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image of the Nyiragonga volcano eruption in the Congo was acquired on January 28, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14spectral 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 will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    Image: A river of molten rock poured from the Nyiragongo volcano in the Congo on January 18, 2002, a day after it erupted, killing dozens, swallowing buildings and forcing hundreds of thousands to flee the town of Goma. The flow continued into Lake Kivu. The lave flows are depicted in red on the image indicating they are still hot. Two of them flowed south form the volcano's summit and went through the town of Goma. Another flow can be seen at the top of the image, flowing towards the northwest. One of Africa's most notable volcanoes, Nyiragongo contained an active lava lake in its deep summit crater that drained catastrophically through its outer flanks in 1977. Extremely fluid, fast-moving lava flows draining from the summit lava lake in 1977 killed 50 to 100 people, and several villages were destroyed. The image covers an area of 21 x 24 km and combines a thermal band in red, and two infrared bands in green and blue.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the

  2. Spectral Analysis of the Signals Associated with Increased Activity in Popocatepetl Volcano April 2012

    NASA Astrophysics Data System (ADS)

    Cuenca, J.

    2013-05-01

    After several decades of being inactive in 1994 had a strong reactivation. Since then he has had long periods where volcanic activity including increased growth and destruction of a dome. In April 2012 Popocatepetl Volcano activity showed an increase in the emission of gas and ash, and Vulcanian type explosions. As a result the National Center for Disaster Prevention (CENAPRED) raised the yellow phase from 2 to 3. Spectrally analyzes seismic activity characteristic of the types of events (explosions, LP, Type-B and tremors) that provides information of the source processes that cause it, despite sustained change reflected by the complexity of the volcanic apparatus, through of: 1) the spectral content of the process provides the source, 2) the spectral ratio H / V, its associated amplification and dominant frequencies, 3) time frequency analysis showing the variation in frequency, 4) the particle motion to analyze its retrograde or prograde acting in a volcanic complex medium. The calculation of H / V was performed by each hour using windows with duration of 80 seconds in the broadband seismic station "Canario" (PPPB). The predominant frequencies of H / V are around 1.4-1.8 Hz to 2.1-2.6 Hz and amplifications from 2.3 to 6.9 times. Analysis of H / V of 48 hours (days 16 and April 17) for the case of 1.4-1.8 Hz was observed: (1) From 0-9 hours there is no amplification. (2) The seismic amplification increases from 10 to 11 hours. (3) A first crisis reaches a maximum at 13 hours with about 6 times of amplification. (4) From 14 to 15 hours there is a strong relaxation of the activity. (5) The activity begins to increase from 16 to 23 hours where it reaches its maximum amplification of almost 7 times. (6) The following two hours and is kept exceeding 6 times of amplification. (7) Then is followed by a decrease to 4 hours on the day 17, from which is maintained at a level variable. (8) At 18 hours of the day 17 grows the amplification at 6.2 times, which conforms a

  3. Characterising Seismicity at Alutu, an Actively Deforming Volcano in the Main Ethiopian Rift

    NASA Astrophysics Data System (ADS)

    Wilks, M.; Nowacki, A.; Kendall, J. M.; Wookey, J. M.; Biggs, J.; Bastow, I. D.; Ayele, A.; Bedada, T.

    2013-12-01

    The Main Ethiopian Rift (MER) provides a unique example of the tectonic and volcanic processes occuring during the transition from continental rifting to oceanic spreading. Situated 100 km south of Addis Ababa along the eastern rift margin, Alutu is a silicic stratovolcano that geodetic measurements (InSAR and GPS) have shown is actively deforming. Though the volcano has received relatively little scientific attention it is also a site of economic significance as a geothermal power plant resides within the caldera. As part of ARGOS (Alutu Research Geophysical ObservationS), a multi-disciplinary project aiming to investigate the magmatic and hydrothermal processes occuring at Alutu, a seismic network of 12 broadband seismometers was deployed in January 2012. Other components of ARGOS include InSAR, GPS, geologic mapping and magnetotellurics. From the seismic dataset, P- and S-wave arrivals across the array were manually picked and used to locate events using a non-linear earthquake location algorithm (NonLinLoc) and a predefined 1D velocity model. Perturbations were later applied to this velocity model to investigate the sensitivity of the locations and evaluate the true uncertainties of the solutions. Over 1000 events were successfully located during 2012, where picks were possible at 4 or more stations. Seismicity clusters at both shallow depths (z<2 km) beneath the caldera and at deeper depths of 5-15 km. There is a significant increase in seismicity during the rainy months, suggesting the shallow events may be related to the hydrothermal system. We interpret the deeper events as being magmatic in origin. Events are also located along the eastern border faults that bound the outer edges of the MER and highlights that seismicity arises concurrently via tectonic processes. An adapted version of Richter's original local magnitude scale (ML) to account for attenuation within the MER (Keir et al., 2006) was then used to compute magnitudes for the best located events

  4. Dynamics and kinematics of eruptive activity at Fuego volcano, Guatemala 2005--2009

    NASA Astrophysics Data System (ADS)

    Lyons, John J.

    Volcanoes are the surficial expressions of complex pathways that vent magma and gasses generated deep in the Earth. Geophysical data record at least the partial history of magma and gas movement in the conduit and venting to the atmosphere. This work focuses on developing a more comprehensive understanding of explosive degassing at Fuego volcano, Guatemala through observations and analysis of geophysical data collected in 2005--2009. A pattern of eruptive activity was observed during 2005--2007 and quantified with seismic and infrasound, satellite thermal and gas measurements, and lava flow lengths. Eruptive styles are related to variable magma flux and accumulation of gas. Explosive degassing was recorded on broadband seismic and infrasound sensors in 2008 and 2009. Explosion energy partitioning between the ground and the atmosphere shows an increase in acoustic energy from 2008 to 2009, indicating a shift toward increased gas pressure in the conduit. Very-long-period (VLP) seismic signals are associated with the strongest explosions recorded in 2009 and waveform modeling in the 10--30 s band produces a best-fit source location 300 m west and 300 m below the summit crater. The calculated moment tensor indicates a volumetric source, which is modeled as a dike feeding a SW-dipping (35°) sill. The sill is the dominant component and its projection to the surface nearly intersects the summit crater. The deformation history of the sill is interpreted as: (1) an initial inflation due to pressurization, followed by (2) a rapid deflation as overpressure is explosively release, and finally (3) a reinflation as fresh magma flows into the sill and degasses. Tilt signals are derived from the horizontal components of the seismometer and show repetitive inflation-deflation cycles with a 20 minute period coincident with strong explosions. These cycles represent the pressurization of the shallow conduit and explosive venting of overpressure that develops beneath a partially

  5. Metal enrichment of soils following the April 2012-2013 eruptive activity of the Popocatépetl volcano, Puebla, Mexico.

    PubMed

    Rodriguez-Espinosa, P F; Jonathan, M P; Morales-García, S S; Villegas, Lorena Elizabeth Campos; Martínez-Tavera, E; Muñoz-Sevilla, N P; Cardona, Miguel Alvarado

    2015-11-01

    We analyzed the total (Zn, Pb, Ni, Hg, Cr, Cd, Cu, As) and partially leachable metals (PLMs) in 25 ash and soil samples from recent (2012-2013) eruptions of the Popocatépetl Volcano in Central Mexico. More recent ash and soil samples from volcanic activity in 2012-2013 had higher metal concentrations than older samples from eruptions in 1997 suggesting that the naturally highly volatile and mobile metals leach into nearby fresh water sources. The higher proportions of As (74.72%), Zn (44.64%), Cu (42.50%), and Hg (32.86%) reflect not only their considerable mobility but also the fact that they are dissolved and accumulated quickly following an eruption. Comparison of our concentration patterns with sediment quality guidelines indicates that the Cu, Cd, Cr, Hg, Ni, and Pb concentrations are higher than permissible limits; this situation must be monitored closely as these concentrations may reach lethal levels in the future. PMID:26514800

  6. Reunion Island Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On January 16, 2002, lava that had begun flowing on January 5 from the Piton de la Fournaise volcano on the French island of Reunion abruptly decreased, marking the end of the volcano's most recent eruption. These false color MODIS images of Reunion, located off the southeastern coast of Madagascar in the Indian Ocean, were captured on the last day of the eruption (top) and two days later (bottom). The volcano itself is located on the southeast side of the island and is dark brown compared to the surrounding green vegetation. Beneath clouds (light blue) and smoke, MODIS detected the hot lava pouring down the volcano's flanks into the Indian Ocean. The heat, detected by MODIS at 2.1 um, has been colored red in the January 16 image, and is absent from the lower image, taken two days later on January 18, suggesting the lava had cooled considerably even in that short time. Earthquake activity on the northeast flank continued even after the eruption had stopped, but by January 21 had dropped to a sufficiently low enough level that the 24-hour surveillance by the local observatory was suspended. Reunion is essentially all volcano, with the northwest portion of the island built on the remains of an extinct volcano, and the southeast half built on the basaltic shield of 8,630-foot Piton de la Fournaise. A basaltic shield volcano is one with a broad, gentle slope built by the eruption of fluid basalt lava. Basalt lava flows easily across the ground remaining hot and fluid for long distances, and so they often result in enormous, low-angle cones. The Piton de la Fournaise is one of Earth's most active volcanoes, erupting over 150 times in the last few hundred years, and it has been the subject of NASA research because of its likeness to the volcanoes of Mars. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  7. Locadiff with ambient seismic noise : theoretical background and application to monitoring volcanoes and active faults.

    NASA Astrophysics Data System (ADS)

    Larose, Eric; Obermann, Anne; Planes, Thomas; Rossetto, Vincent; Margerin, Ludovic; Sens-Schoenfelder, Christoph; Campillo, Michel

    2015-04-01

    This contribution will cover recent theoretical, numerical, and field data processing developments aiming at modeling how coda waves are perturbed (in phase and amplitude) by mechanical changes in the crust. Using continuous ambient seismic noise, we cross-correlate data every day and compare the coda of the correlograms. We can relative velocity changes and waveform decorrelation along the year, that are related to mechanical changes in the shallow crust, associated to the seismic or volcanic activity, but also to environmental effects such as hydrology. Bibliography : Anne Obermann, Thomas Planes, Eric Larose and Michel Campillo, Imaging pre- and co-eruptive structural changes of a volcano with ambient seismic noise, J. Geophys. Res. 118 6285-6294 (2013). A. Obermann, B. Froment, M. Campillo, E. Larose, T. Planès, B. Valette, J. H. Chen, and Q. Y. Liu, Seismic noise correlations to image structural and mechanical changes associated with the Mw7.9 2008-Wenchuan earthquake, J. Geophys. Res. Solid Earth, 119, 1-14,(2014). Thomas Planès, Eric Larose, Ludovic Margerin, Vincent Rossetto, Christoph Sens-Schoenfelder, Decorrelation and phase-shift of coda waves induced by local changes : Multiple scattering approach and numerical validation, Waves in Random and Complex Media 24, 99-125, (2014)

  8. Landform monitoring in active volcano by UAV and SfM-MVS technique

    NASA Astrophysics Data System (ADS)

    Nakano, T.; Kamiya, I.; Tobita, M.; Iwahashi, J.; Nakajima, H.

    2014-11-01

    Nishinoshima volcano in Ogasawara Islands has erupted since November, 2013. This volcanic eruption formed and enlarged a new island, and fused the new island with the old Nishinoshima Island. We performed automated aerial photographing using an Unmanned Aerial Vehicle (UAV) over the joined Nishinoshima Island on March 22 and July 4, 2014. We produced ortho-mosaic photos and digital elevation model (DEM) data by new photogrammetry software with computer vision technique, i.e. Structure from Motion (SfM) for estimating the photographic position of the camera and Multi-view Stereo (MVS) for generating the 3-D model. We also estimated the area and volume of the new island via analysis of ortho-mosaic photo and DEM data. Transition of volume estimated from the UAV photographing and other photographing shows the volcanic activity still keeps from initial level. The ortho-mosaic photos and DEM data were utilized to create an aerial photo interpretation map and a 3-D map. These operations revealed new knowledge and problems to be solved on the photographing and analysis using UAV and new techniques as this was first case in some respects.

  9. Near-bottom water column anomalies associated with active hydrothermal venting at Aeolian arc volcanoes, Tyrrhenian Sea, Italy

    NASA Astrophysics Data System (ADS)

    Walker, S. L.; Carey, S.; Bell, K. L.; Baker, E. T.; Faure, K.; Rosi, M.; Marani, M.; Nomikou, P.

    2012-12-01

    Hydrothermal deposits such as metalliferous sediments, Fe-Mn crusts, and massive sulfides are common on the submarine volcanoes of the Aeolian arc (Tyrrhenian Sea, Italy), but the extent and style of active hydrothermal venting is less well known. A systematic water column survey in 2007 found helium isotope ratios indicative of active venting at 6 of the 9 submarine volcanoes surveyed plus the Marsili back-arc spreading center (Lupton et al., 2011). Other plume indicators, such as turbidity and temperature anomalies were weak or not detected. In September 2011, we conducted five ROV Hercules dives at Eolo, Enarete, and Palinuro volcanoes during an E/V Nautilus expedition. Additionally, two dives explored the Casoni seamount on the southern flank of Stromboli where a dredge returned apparently warm lava in 2002 (Gamberi, 2006). Four PMEL MAPRs, with temperature, optical backscatter (particles), and oxidation-reduction potential (ORP) sensors, were arrayed along the lowermost 50 m of the Hercules/Argus cable during the dives to assess the relationship between seafloor observations and water column anomalies. Active venting was observed at each of the volcanoes visited. Particle anomalies were weak or absent, consistent with the 2007 CTD surveys, but ORP anomalies were common. Venting at Eolo volcano was characterized by small, localized patches of yellow-orange bacteria; living tubeworms were observed at one location. ORP anomalies (-1 to -22 mv) were measured at several locations, primarily along the walls of the crescent-shaped collapse area (or possible caldera) east of the Eolo summit. At Enarete volcano, we found venting fluids with temperatures up to 5°C above ambient as well as small, fragile iron-oxide chimneys. The most intense ORP anomaly (-140 mv) occurred at a depth of about 495 m on the southeast side of the volcano, with smaller anomalies (-10 to -20 mv) more common as the ROV moved upslope to the summit. At Palinuro volcano, multiple dives located

  10. Monitoring crater-wall collapse at active volcanoes: a study of the 12 January 2013 event at Stromboli

    NASA Astrophysics Data System (ADS)

    Calvari, Sonia; Intrieri, Emanuele; Di Traglia, Federico; Bonaccorso, Alessandro; Casagli, Nicola; Cristaldi, Antonio

    2016-05-01

    Crater-wall collapses are fairly frequent at active volcanoes and they are normally studied through the analysis of their deposits. In this paper, we present an analysis of the 12 January 2013 crater-wall collapse occurring at Stromboli volcano, investigated by means of a monitoring network comprising visible and infrared webcams and a Ground-Based Interferometric Synthetic Aperture Radar. The network revealed the triggering mechanisms of the collapse, which are comparable to the events that heralded the previous effusive eruptions in 1985, 2002, 2007 and 2014. The collapse occurred during a period of inflation of the summit cone and was preceded by increasing explosive activity and the enlargement of the crater. Weakness of the crater wall, increasing magmastatic pressure within the upper conduit induced by ascending magma and mechanical erosion caused by vent opening at the base of the crater wall and by lava fingering, are considered responsible for triggering the collapse on 12 January 2013 at Stromboli. We suggest that the combination of these factors might be a general mechanism to generate crater-wall collapse at active volcanoes.

  11. Active sulfur cycling by diverse mesophilic and thermophilic microorganisms in terrestrial mud volcanoes of Azerbaijan.

    PubMed

    Green-Saxena, A; Feyzullayev, A; Hubert, C R J; Kallmeyer, J; Krueger, M; Sauer, P; Schulz, H-M; Orphan, V J

    2012-12-01

    Terrestrial mud volcanoes (TMVs) represent geochemically diverse habitats with varying sulfur sources and yet sulfur cycling in these environments remains largely unexplored. Here we characterized the sulfur-metabolizing microorganisms and activity in four TMVs in Azerbaijan. A combination of geochemical analyses, biological rate measurements and molecular diversity surveys (targeting metabolic genes aprA and dsrA and SSU ribosomal RNA) supported the presence of active sulfur-oxidizing and sulfate-reducing guilds in all four TMVs across a range of physiochemical conditions, with diversity of these guilds being unique to each TMV. The TMVs varied in potential sulfate reduction rates (SRR) by up to four orders of magnitude with highest SRR observed in sediments where in situ sulfate concentrations were highest. Maximum temperatures at which SRR were measured was 60°C in two TMVs. Corresponding with these trends in SRR, members of the potentially thermophilic, spore-forming, Desulfotomaculum were detected in these TMVs by targeted 16S rRNA analysis. Additional sulfate-reducing bacterial lineages included members of the Desulfobacteraceae and Desulfobulbaceae detected by aprA and dsrA analyses and likely contributing to the mesophilic SRR measured. Phylotypes affiliated with sulfide-oxidizing Gamma- and Betaproteobacteria were abundant in aprA libraries from low sulfate TMVs, while the highest sulfate TMV harboured 16S rRNA phylotypes associated with sulfur-oxidizing Epsilonproteobacteria. Altogether, the biogeochemical and microbiological data indicate these unique terrestrial habitats support diverse active sulfur-cycling microorganisms reflecting the in situ geochemical environment. PMID:23116231

  12. An active ring fault detected at Tendürek volcano by using InSAR

    NASA Astrophysics Data System (ADS)

    Bathke, H.; Sudhaus, H.; Holohan, E. P.; Walter, T. R.; Shirzaei, M.

    2013-08-01

    ring faults are present at many ancient, deeply eroded volcanoes, they have been detected at only very few modern volcanic centers. At the so far little studied Tendürek volcano in eastern Turkey, we generated an ascending and a descending InSAR time series of its surface displacement field for the period from 2003 to 2010. We detected a large (~105 km2) region that underwent subsidence at the rate of ~1 cm/yr during this period. Source modeling results show that the observed signal fits best to simulations of a near-horizontal contracting sill located at around 4.5 km below the volcano summit. Intriguingly, the residual displacement velocity field contains a steep gradient that systematically follows a system of arcuate fractures visible on the volcano's midflanks. RapidEye satellite optical images show that this fracture system has deflected Holocene lava flows, thus indicating its presence for at least several millennia. We interpret the arcuate fracture system as the surface expression of an inherited ring fault that has been slowly reactivated during the detected recent subsidence. These results show that volcano ring faults may not only slip rapidly during eruptive or intrusive phases, but also slowly during dormant phases.

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

    PubMed

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

    2013-01-01

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

  14. Results From NICLAKES Survey of Active Faulting Beneath Lake Nicaragua, Central American Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Funk, J.; Mann, P.; McIntosh, K.; Wulf, S.; Dull, R.; Perez, P.; Strauch, W.

    2006-12-01

    In May of 2006 we used a chartered ferry boat to collect 520 km of seismic data, 886 km of 3.5 kHz subbottom profiler data, and 35 cores from Lake Nicaragua. The lake covers an area of 7700 km2 within the active Central American volcanic arc, forms the largest lake in Central America, ranks as the twentieth largest freshwater lake in the world, and has never been previously surveyed or cored in a systematic manner. Two large stratovolcanoes occupy the central part of the lake: Concepcion is presently active, Maderas was last active less than 2000 years ago. Four zones of active faulting and doming of the lake floor were mapped with seismic and 3.5 kHz subbottom profiling. Two of the zones consist of 3-5-km-wide, 20-30-km-long asymmetric rift structures that trend towards the inactive cone of Maderas Volcano in a radial manner. The northeastern rift forms a 20-27-m deep depression on the lake bottom that is controlled by a north-dipping normal fault. The southwestern rift forms a 25-35-m deep depression controlled by a northeast-dipping normal fault. Both depressions contain mound-like features inferred to be hydrothermal deposits. Two zones of active faulting are associated with the active Concepcion stratovolcano. A 600-m-wide and 6-km-long fault bounded horst block extends westward beneath the lake from a promontory on the west side of the volcano. Like the two radial rift features of Maderas, the horst points roughly towards the active caldera of Concepcion. A second north-south zone of active faulting, which also forms a high, extends off the north coast of Concepcion and corresponds to a localized zone of folding and faulting mapped by previous workers and inferred by them to have formed by gravitational spreading of the flank of the volcano. The close spatial relation of these faults to the two volcanic cones in the lake suggests that the mechanism for faulting is a result of either crustal movements related to magma intrusion or gravitational sliding and is

  15. Ongoing Active Deformation Processes at Fernandina Volcano (Galapagos) Detected via Multi-Orbit COSMO-SkyMed SAR Data Analysis

    NASA Astrophysics Data System (ADS)

    Pepe, Susi; Castaldo, Raffaele; De Luca, Claudio; Casu, Francesco; Tizzani, Pietro; Sansosti, Eugenio

    2014-05-01

    Fernandina Volcano, Galápagos (Ecuador), has experienced several uplift and eruption episodes over the last twenty-two years. The ground deformation between 2002 and 2006 was interpreted as the effect of an inflation phenomenon of two separate magma reservoirs beneath the caldera. Moreover, the uplift deformation occurred during the 2005 eruption was concentrated near the circumferential eruptive fissures, while being superimposed on a broad subsidence centred on the caldera. The geodetic studies emphasized the presence of two sub volcanic lateral intrusions from the central storage system in December 2006 and August 2007. The latest eruption in 2009 was characterized by lava flows emitted from the SW radial fissures. We analyze the spatial and temporal ground deformation between March 2012 and July 2013, by using data acquired by COSMO-SkyMed X-band constellation along both ascending and descending orbits and by applying advanced InSAR techniques. In particular, we use the SBAS InSAR approach and combine ascending and descending time series to produce vertical and East-West components of the mean deformation velocity and deformation time series. Our analysis revealed a new uplift phenomenon due to the stress concentration inside the shallow magmatic system of the volcano. In particular, the vertical mean velocity map shows that the deformation pattern is concentrated inside caldera region and is characterized by strongly radial symmetry with a maximum displacement of about 20 cm in uplift; an axial symmetry is also observed in the EW horizontal mean velocity map, showing a maximum displacement of about +12 cm towards East for the SE flank, and -12 cm towards West for the NW flank of the volcano. Moreover, the deformation time series show a rather linear uplift trend from March to September 2012, interrupted by a low deformation rate interval lasting until January 2013. After this stage, the deformation shows again a linear behaviour with an increased uplift rate

  16. The 2005 and 2006 eruptions of Ol Doinyo Lengai: assessing deep and shallow processes at an active carbonatite volcano using volatile chemistry and fluxes

    NASA Astrophysics Data System (ADS)

    Fischer, T.; Burnard, P.; Marty, B.; Palhol, F.; Mangasini, F.; Shaw, A. M.

    2006-12-01

    The African Rift valleys are sites of classical carbonatite volcano complexes. Ol Doinyo Lengai, the spectacular cone that rises to nearly 3000 m above Tanzania's Eastern Rift Valley, is the world's only active carbonatite volcano. High-alkali carbonatite lavas from this volcano were first recognized in the 1960's and the oldest natrocarbonatite tuffs have been dated to 1250 years B.P.. Earlier eruptions produced phonolitic and nephelinitc lavas [1]. Since the 1960's the volcano has erupted frequently producing carbonatite lava flows. Explosive eruptions are much less frequent but have occurred in 1966, 1983 [1] and 1993 [3] producing ash, cones and natrocarbonatite tephra. In July 2005, we launched an expedition to the crater to collect gas and rock samples. On July 4, the volcano began erupting low viscosity, low T (540C) high velocity (2 m/sec) lava flows at a rate of about 0.3 m3/sec. By afternoon, the lava was flowing over the eastern crater rim. During the eruption we sampled gases from nearby hornitos at 120 and 168C, yielding pristine magmatic gases characterized by 75 mol% H2O, 22% CO2, < 1% SO2, H2S, HCl and traces of H2, He, Ar, N2, CH4 and CO. CO2-CH4-CO gas equilibrium temperatures are 580C consistent with lava flow temperatures. N2-He-Ar abundances indicate an upper mantle origin of volatiles, confirmed by isotopes [4]. SO2 flux measured by mini DOAS was low (10 t/day). CO2 fluxes calculated using CO2/SO2 are 3000 to 4000 t/day. Volatiles measured in the carbonatite lavas by SIMS show low H2O (< 0.7 wt%), high S (0.2 to 1 wt%) and Cl (0.6 to 1.4 wt%) and variable F (0.06 to 0.7 wt%). CO2 contents are 30 wt% with major and trace elements typical of natrocarbonatite lavas previously reported in [1]. The release of all CO2 (30 wt% or 20 t/day) from eruption lavas would only produce a small fraction of the measured CO2. In March 2006 eyewitnesses [3] reported the occurrence of an explosive eruption and some of us returned to the volcano on May 12. The

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

    NASA Astrophysics Data System (ADS)

    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

  18. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania

    USGS Publications Warehouse

    Kervyn, M.; Ernst, G.G.J.; Keller, J.; Vaughan, R. Greg; Klaudius, J.; Pradal, E.; Belton, F.; Mattsson, H.B.; Mbede, E.; Jacobs, P.M.

    2010-01-01

    On September 4, 2007, after 25 years of effusive natrocarbonatite eruptions, the eruptive activity of Oldoinyo Lengai (OL), N Tanzania, changed abruptly to episodic explosive eruptions. This transition was preceded by a voluminous lava eruption in March 2006, a year of quiescence, resumption of natrocarbonatite eruptions in June 2007, and a volcano-tectonic earthquake swarm in July 2007. Despite the lack of ground-based monitoring, the evolution in OL eruption dynamics is documented based on the available field observations, ASTER and MODIS satellite images, and almost-daily photos provided by local pilots. Satellite data enabled identification of a phase of voluminous lava effusion in the 2 weeks prior to the onset of explosive eruptions. After the onset, the activity varied from 100 m high ash jets to 2–15 km high violent, steady or unsteady, eruption columns dispersing ash to 100 km distance. The explosive eruptions built up a ∼400 m wide, ∼75 m high intra-crater pyroclastic cone. Time series data for eruption column height show distinct peaks at the end of September 2007 and February 2008, the latter being associated with the first pyroclastic flows to be documented at OL. Chemical analyses of the erupted products, presented in a companion paper (Keller et al.2010), show that the 2007–2008 explosive eruptions are associated with an undersaturated carbonated silicate melt. This new phase of explosive eruptions provides constraints on the factors causing the transition from natrocarbonatite effusive eruptions to explosive eruptions of carbonated nephelinite magma, observed repetitively in the last 100 years at OL.

  19. A Sinuous Tumulus over an Active Lava Tube at Klauea Volcano: Evolution, Analogs, and Hazard Forecasts

    NASA Technical Reports Server (NTRS)

    Orr, Tim R.; Bleacher, Jacob E.; Patrick, Matthew R.; Wooten, Kelly M.

    2015-01-01

    Inflation of narrow tube-fed basaltic lava flows (tens of meters across), such as those confined by topography, can be focused predominantly along the roof of a lava tube. This can lead to the development of an unusually long tumulus, its shape matching the sinuosity of the underlying lava tube. Such a situation occurred during Klauea Volcanos (Hawaii, USA) ongoing East Rift Zone eruption on a lava tube active from July through November 2010. Short-lived breakouts from the tube buried the flanks of the sinuous, ridge-like tumulus, while the tumulus crest, its surface composed of lava formed very early in the flows emplacement history, remained poised above the surrounding younger flows. At least several of these breakouts resulted in irrecoverable uplift of the tube roof. Confined sections of the prehistoric Carrizozo and McCartys flows (New Mexico, USA) display similar sinuous, ridge-like features with comparable surface age relationships. We contend that these distinct features formed in a fashion equivalent to that of the sinuous tumulus that formed at Kilauea in 2010. Moreover, these sinuous tumuli may be analogs for some sinuous ridges evident in orbital images of the Tharsis volcanic province on Mars. The short-lived breakouts from the sinuous tumulus at Kilauea were caused by surges in discharge through the lava tube, in response to cycles of deflation and inflation (DI events) at Kilauea's summit. The correlation between DI events and subsequent breakouts aided in lava flow forecasting. Breakouts from the sinuous tumulus advanced repeatedly toward the sparsely populated Kalapana Gardens subdivision, destroying two homes and threatening others. Hazard assessments, including flow occurrence and advance forecasts, were relayed regularly to the Hawai?i County Civil Defense to aid their lava flow hazard mitigation efforts while this lava tube was active.

  20. 2012 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2014-01-01

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

  1. Geochemical heterogeneities and dynamics of magmas inside the plumbing system of a persistently active volcano: evidences from Stromboli

    NASA Astrophysics Data System (ADS)

    Pompilio, Massimo; Bertagnini, Antonella; Métrich, Nicole; Belhadj, Oulfa

    2010-05-01

    Shallow processes such as degassing, crystallization and magma drain-back commonly operate in the upper parts of the plumbing systems of open-conduit basaltic volcanoes, often hindering the identification of potentially important geochemical changes in the volcano systems. Stromboli, known for its long-lived persistent activity over the last 18 centuries, is a suitable subject of study for addressing this issue, since basaltic magmas presently erupting at in this volcano record both deep and shallow processes. We report petrological and geochemical data on magmas erupted by Stromboli since the beginning of the persistent activity, in order to find a correlation between magma composition and the dynamics of magma in the plumbing system. Geochemical data on deep-derived magmas erupted as pumice during paroxysmal eruptions allowed us to identify two distinct parental melts (1944- and 2003-Type). These magmas, in which geochemical differences are linked to source processes rather than crystal fractionation, have alternately fed the deep reservoir in the last two millennia several times. The chemical heterogeneities recorded in lava flows and the products of Strombolian activity testify to the extent of homogenization after magma recharges at shallow depths. Persistent heterogeneities in the shallow plumbing system have important implications for magma residence times calculated on the basis of time-series analysis. These models are based on the assumptions that the reservoir is well stirred and chemically homogeneous and that the time for the re-homogenization after recharge (or mixing) is shorter than the residence time. We argue that these models do not apply to present-day activity at Stromboli and may not apply to other open-conduit, persistently degassing basaltic volcanoes. Thus compositional variations within the shallow magma bodies provide only a biased signal of ongoing changes within the plumbing system. We conclude that source changes responsible for

  2. Modeling and measurement of the volcanic ash plume transport from the Eyjafjallajökull volcano towards Central Europe in April 2010-Methods applied and lessons learned

    NASA Astrophysics Data System (ADS)

    Wotawa, G.; Kerschbaum, M.

    2010-09-01

    On 14 April 2010, a VEI-4 eruption occurred at the Eyjafjallajoekull volcano in Iceland, which continued for a number of days. Within the first 72 hours, more than 0.1 km3 Tephra were released. Due to the prevailing weather conditions, volcanic ash was rapidly transported from Iceland towards Central Europe. The ash plume reached Southern England on 15 April, crossed Germany on 16 April and reached the Alps in the morning hours of 17 April. As a consequence, European air travel broke down almost completely, and flights were grounded for a number of days. In this presentation, we describe the methods applied by the national weather service of Austria and the Austrian national aviation authorities to handle the situation, taking into account also international response systems and mechanisms. Furthermore, we discuss the model results in combination with available observations, and outline the lessons learned from this event. Based on this analysis, improvements in modeling and enhancement of procedures are proposed.

  3. Cost effective aero-photogrammetry toys at active volcanoes: On the use of drones, balloons and kites

    NASA Astrophysics Data System (ADS)

    Walter, Thomas R.

    2014-05-01

    The availability of aerial photographs allows spatial mapping of flows and fractures, generation of digital elevation models and other change detection. Therefore aerial photographs significantly improve our understanding of volcanic processes. The common problem is the lack of available data for most volcanoes, and the lack of systematic and chronologic repeat surveys. This work summarizes the current state of knowledge and technical implementations that currently revolutionize the field of aero-photogrammetry. By the use of unmanned vehicles, such as octocopters, helicopters and small airplanes, photo data can be acquired from almost any place at distances up to kilometres from the operator. Moreover, by the use of helium balloons, kites or their hybrid helikites, near field aero-photographs are obtained. In combination with modern stitching procedures and computer vision algorithms, the positioning of the camera and the digital elevation model of the ground can be extracted, and the active volcano and its eruption cloud be imaged from almost any perspective. This field is increasingly gaining flexibility, as lightweight cameras are available from visible, infrared and other spectral bands. Here example data are provided from volcanoes that are difficult to access by regular airplanes, showing the strengths and the limits of these new aero-photogrammetry toys.

  4. Evolution of magma feeding system in Kumanodake agglutinate activity, Zao Volcano, northeastern Japan

    NASA Astrophysics Data System (ADS)

    Takebe, Yoshinori; Ban, Masao

    2015-10-01

    The Kumanodake agglutinate of Zao Volcano in northeastern Japan consists of pyroclastic surge layers accumulated during the early part of the newest stage of activity (ca. 33 ka to present). Our petrologic study of this agglutinate based on systematically collected samples aims to reveal the evolution of magma feeding system. To understand the magma evolution, we have examined samples from the agglutinate by using petrologic data including, petrography, analysis of minerals (plagioclase, pyroxene, and olivine), glass compositions, and whole rock major element and trace element (Ba, Sr, Cr, Ni, V, Rb, Zr, Nb, and Y) compositions. Agglutinate are mixed, medium-K, calc-alkaline olv-cpx-opx basaltic andesite (55.2-56.2% SiO2). Results show that the magma feeding system comprised a shallow felsic chamber injected by mafic magma from depth. The felsic magma (59-62% SiO2, 950-990 °C), which was stored at a shallower depth, had orthopyroxene (Mg# = 60-69), clinopyroxene (Mg# = 65-71), and low-An plagioclase (Anca. 58-70). The mafic magma is further divisible into two types: less-differentiated and more-differentiated, designed respectively as an initial mafic magma-1 and a second mafic magma-2. The original mafic magma-1 was olivine (Fo~ 84) basalt (ca. 48-51% SiO2, 1110-1140 °C). The second mafic magma-2, stored occasionally at 4-6 km depth, was basalt (1070-1110 °C) having Foca. 80 olivine and high-An (Anca. 90) plagioclase phenocrysts. These two magmas mixed (first mixing) to form hybrid mafic magma. The forced injections of the hybrid mafic magmas activated the felsic magma, and these two were mixed (second mixing) shortly before eruptions. The explosivity is inferred to have increased over time because the abundance of large scoria increased. Furthermore, the erupted magma composition became more mafic, which reflects increased percentage of the hybrid mafic magma involved in the second mixing. At the beginning of activity, the mafic magma also acted as a heat

  5. Observations of the Electrical Activity of the Redoubt Volcano in Alaska

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    The Mt. Redoubt volcano in Alaska underwent a series of 22 major explosive eruptions over a 2.5 week period between 23 March and 4 April 2009. We were able to deploy a 4-station Lightning Mapping Array (LMA) in advance of the eruptions along a 60 km stretch of the Kenai coastline, 70-80 km east of Redoubt on the opposite side of Cook Inlet, and to monitor and control the station operations remotely via internet connections. The LMA data show that the eruptions produced spectacular lightning, both over and downwind of the volcano, lasting between 20 to 80 minutes depending on the eruption strength. The discharging was essentially continuous during the initial stages of the eruptions and gradually evolved into more discrete and spatially structured discharges displaced from 10 km up to 80 or 90 km away from Redoubt. The discharge rates and VHF radiation signals were comparable to or greater than observed in Great Plains thunderstorms, with discernible but complex 'flashes' occurring at a rate of 2-3 per second in the active stages of eruptions, decaying to about 10-15 per minute of horizontally extensive discrete discharges in later stages. Individual eruptions produced literally thousands of discharges. The approximately linear array of the mapping stations, coupled with their distance from Redoubt and the inability to have a station at a closer distance, has precluded obtaining useful altitude information from the time-of-arrival data. The exception has been lightning at the end of the March 28 eruption as the plume cloud drifted over the northern end of the LMA network; which showed negative charge at 6 km altitude and positive charge between 8 and 9 km altitude, exactly the same as seen in normally electrified thunderstorms. Three of the four stations had been deployed on 50-100m high bluffs overlooking Cook Inlet in an attempt to use sea-surface interference effects to determine altitude, as in our study of the 2006 Augustine eruptions. But only partial

  6. The occurrence of a complete continental rift type of volcanic rocks suite along the Yerer-Tullu Wellel Volcano Tectonic Lineament, Central Ethiopia

    NASA Astrophysics Data System (ADS)

    Abebe Adhana, Tsegaye

    2014-11-01

    The Yerer-Tullu Wellel Volcano-tectonic Lineament (YTVL) is an E-W trending fault system or aborted rift that intercepts the Main Ethiopian Rift (MER) at Debre Zeyt (Bishoftu)/Yerer, in the eastern periphery of Addis Ababa. The structure is in correspondence with the westward extension of the southern margin of the Gulf of Aden rift. The YTVL extends for more than 500 km with a very clear northern fault margin, between Addis Ababa and Ambo known as the “Ambo Fault”. The southern margin is indicated by an E-W trending segmented lineaments at the latitude of about N 8°30‧, the Bedele-Metu being the most clear segment. In between these limits there are several evolved central volcanoes and cinder cones. The central volcanoes range in age from 12 to 7 Ma in the western most (Tullu Wellel) and gradually the upper limit get younger towards East to less than 1 Ma in the Wenchi and Debre Zeyt (Bishoftu) areas. These volcanic products cover the whole spectrum of a continental rift volcanic rocks suite: (1) in the eastern zone (Yerer-Bishoftu) the suite is silica over-saturated, ranging in composition from transitional basalt to peralkaline rhyolite, (2) moving westwards, between Wechacha and Wenchi, the rocks suite is silica saturated ranging in composition from alkali basalt to trachyte, (3) further West between Ijaji-Konchi and Nekemt the rocks suite is silica under-saturated ranging in composition from basanite to phonolite. Crossing the Dedessa lineament, the Tullu Wellel rocks appear to be silica saturated. Within a single suite fractional crystallization is the predominant evolutional process even in the silica over-saturated suite. The westwards progressive silica under-saturation and increase in alkalinity (except for the Tullu Wellel volcanic centers) is interpreted by the gradual deepening of an anomalous mantle where partial fusion took place. Therefore, as distance increases from the MER junction to the West, the amount of melt on the upper mantle was

  7. An Interactive Geospatial Database and Visualization Approach to Early Warning Systems and Monitoring of Active Volcanoes: GEOWARN

    NASA Astrophysics Data System (ADS)

    Gogu, R. C.; Schwandner, F. M.; Hurni, L.; Dietrich, V. J.

    2002-12-01

    Large parts of southern and central Europe and the Pacific rim are situated in tectonically, seismic and volcanological extremely active zones. With the growth of population and tourism, vulnerability and risk towards natural hazards have expanded over large areas. Socio-economical aspects, land use, tourist and industrial planning as well as environmental protection increasingly require needs of natural hazard assessment. The availability of powerful and reliable satellite, geophysical and geochemical information and warning systems is therefore increasingly vital. Besides, once such systems have proven to be effective, they can be applied for similar purposes in other European areas and worldwide. Technologies today have proven that early warning of volcanic activity can be achieved by monitoring measurable changes in geophysical and geochemical parameters. Correlation between different monitored data sets, which would improve any prediction, is very scarce or missing. Visualisation of all spatial information and integration into an "intelligent cartographic concept" is of paramount interest in order to develop 2-, 3- and 4-dimensional models to approach the risk and emergency assessment as well as environmental and socio-economic planning. In the framework of the GEOWARN project, a database prototype for an Early Warning System (EWS) and monitoring of volcanic activity in case of hydrothermal-explosive and volcanic reactivation has been designed. The platform-independent, web-based, JAVA-programmed, interactive multidisciplinary multiparameter visualization software being developed at ETH allows expansion and utilization to other volcanoes, world-wide databases of volcanic unrest, or other types of natural hazard assessment. Within the project consortium, scientific data have been acquired on two pilot sites: Campi Flegrei (Italy) and Nisyros Greece, including 2&3D Topography and Bathymetry, Elevation (DEM) and Landscape models (DLM) derived from conventional

  8. Waters associated with an active basaltic volcano, Kilauea, Hawaii: Variation in solute sources, 1973-1991

    USGS Publications Warehouse

    Tilling, R.I.; Jones, B.F.

    1996-01-01

    Chemical and isotopic analyses of samples collected from a 1262-m-deep research borehole at the summit of Kilauea Volcano provide unique time-series data for composition of waters in the uppermost part of its hydrothermal system. These waters have a distinctive geochemical signature: a very low proportion of chloride relative to other anions compared with other Hawaiian wa-ters - thermal (???30 ??C) or nonthermal (<30 ??C) - and with most thermal waters of the world. Isotope data demonstrate that the borehole waters are of essentially meteoric origin, with minimal magmatic input. The water chemistry exhibits marked temporal variations, including pronounced short-term (days to weeks) effects of rainfall dilution and longer term (months to years) decline of total solutes. The 1973-1974 samples are Na-sulfate-dominant, but samples collected after July 1975 are (Mg + Ca)-bicarbonate-dominant. This compositional shift, probably abrupt, was associated with an increase in the partial pressure of CO2 (PCO2) related to volcanic degassing of CO2 accompanying a large eruption (December 31, 1974) and associated intense seismicity. Following the initial sharp increase, the PCO2 then decreased, approaching preemption values in April 1976. Beginning in mid-1975, solute concentrations of the borehole waters decreased substantially, from ???45 meq/L to <25 meq/L in only eight months; by 1991, total solute concentrations were <17 meq/L. This decline in solutes cannot be attributed to rainfall dilution and is inferred to reflect the decreasing availability with time of the easily leachable salts of alkali metals and sulfate, which originated in sublimates and fumarolic encrustations in fractures and cavities of rocks along the hydrologic flow paths. The overall chemistry of the summit-borehole waters is largely determined by hydrolysis reactions associated with normal weathering of host tholeiitic basalts on a geologic time scale, despite short-term perturbations in composition

  9. Observations of Io's Active Volcanoes from IRTF: Imaging and Occultation Lightcurves

    NASA Astrophysics Data System (ADS)

    Rathbun, J. A.; Spencer, J. R.

    2014-12-01

    We have been observing Ionian volcanism from NASA's Infrared Telescope Facility (IRTF) for more than two decades. The frequency of our observations increases dramatically when spacecraft are observing Io in order to complement the data returned by the spacecraft. The Japanese Space Agency's (JAXA) Hisaki (Sprint-A) mission recently observd the Jupiter system from earth orbit, monitoring the Io Plasma Torus and Jovian aurora. In order to investigate the possible influence of Io volcanism on the torus, we observed Io's volcanoes from the IRTF in Hawaii between September 2013 and May 2014. We imaged Io at 2.2, 3.5, and 4.8 microns in eclipse and reflected sunlight. We also observed Io during occultation by Jupiter, which allows us to locate and characterize individual volcanic eruptions, with greater spatial accuracy, on the Jupiter-facing hemisphere. The 2013 3.5 micron images of a sunlit Io showed no obvious bright volcanic features. However, further increases in spatial resolution is possible with shift-and-add processing of short exposure images. Preliminary occultation lightcurves from 2013 show moderate levels of activity at Kaneheliki/Janus and Loki, the two volcanic centers most often observed in occultation lightcurves. Loki was much brighter in 2013 than during the New Horizons flyby in 2007, but not as bright as during the Galileo era (see figure). From February 2014 through May 2014, due to a planned upgrade on the SPEX instrument and an unplanned required repair on the NSFCam2 instrument (both of which we have used previously), we exclusively used the CSHELL instrument as an imager. Unfortunately, CSHELL was not designed for imaging and has limited spatial resolution and photometric precision, complicating image analysis.

  10. Acoustic measurements of the 1999 basaltic eruption of Shishaldin volcano, Alaska 1. Origin of Strombolian activity

    USGS Publications Warehouse

    Vergniolle, S.; Boichu, M.; Caplan-Auerbach, J.

    2004-01-01

    The 1999 basaltic eruption of Shishaldin volcano (Alaska, USA) displayed both classical Strombolian activity and an explosive Subplinian plume. Strombolian activity at Shishaldin occurred in two major phases following the Subplinian activity. In this paper, we use acoustic measurements to interpret the Strombolian activity. Acoustic measurements of the two Strombolian phases show a series of explosions that are modeled by the vibration of a large overpressurised cylindrical bubble at the top of the magma column. Results show that the bubble does not burst at its maximum radius, as expected if the liquid film is stretched beyond its elasticity. But bursting occurs after one cycle of vibration, as a consequence of an instability of the air-magma interface close to the bubble minimum radius. During each Strombolian period, estimates of bubble length and overpressure are calculated. Using an alternate method based on acoustic power, we estimate gas velocity to be 30-60 m/s, in very good agreement with synthetic waveforms. Although there is some variation within these parameters, bubble length and overpressure for the first Strombolian phase are found to be ??? 82 ?? 11 m and 0.083 MPa. For the second Strombolian phase, bubble length and overpressure are estimated at 24 ?? 12 m and 0.15 MPa for the first 17 h after which bubble overpressure shows a constant increase, reaching a peak of 1.4 MPa, just prior to the end of the second Strombolian phase. This peak suggests that, at the time, the magma in the conduit may contain a relatively large concentration of small bubbles. Maximum total gas volume and gas fluxes at the surface are estimated to be 3.3 ?? 107 and 2.9 ?? 103 m3/s for the first phase and 1.0 ?? 108 and 2.2 ?? 103 m3/s for the second phase. This gives a mass flux of 1.2 ?? 103 and 8.7 ?? 102 kg/s, respectively, for the first and the second Strombolian phases. ?? 2004 Elsevier B.V. All rights reserved.

  11. Remote sensing of Italian volcanos

    NASA Technical Reports Server (NTRS)

    Bianchi, R.; Casacchia, R.; Coradini, A.; Duncan, A. M.; Guest, J. E.; Kahle, A.; Lanciano, P.; Pieri, D. C.; Poscolieri, M.

    1990-01-01

    The results of a July 1986 remote sensing campaign of Italian volcanoes are reviewed. The equipment and techniques used to acquire the data are described and the results obtained for Campi Flegrei and Mount Etna are reviewed and evaluated for their usefulness for the study of active and recently active volcanoes.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  13. Seismic structure and origin of active intraplate volcanoes in Northeast Asia

    NASA Astrophysics Data System (ADS)

    Duan, Yonghong; Zhao, Dapeng; Zhang, Xiankang; Xia, Shaohong; Liu, Zhi; Wang, Fuyun; Li, Li

    2009-05-01

    Three-dimensional P-wave velocity structure beneath the Changbai and other intraplate volcanic areas in Northeast Asia is determined by inverting 1378 high-quality P-wave arrival times from 186 teleseismic events recorded by 61 broadband seismic stations. Low-velocity (low-V) anomalies are revealed beneath the Changbai, Longgan, Xianjindao volcanoes. High-velocity (high-V) anomalies are found in the mantle transition zone, where deep-focus earthquakes under Hunchun occur at depths of 500-600 km. The high-V anomaly reflects the deep subduction of the Pacific slab under NE Asia which may have contributed to the formation of the Changbai, Longgang, Xianjindao and Jingpohu intraplate volcanoes. A low-V anomaly is also revealed in the mantle transition zone, which may have a close relationship with the occurrence of deep earthquakes under the Hunchun area. Our results support the Big Mantle Wedge (BMW) model by Zhao et al. [Zhao, D., Lei, J., Tang, Y., 2004. Origin of the Changbai volcano in northeast China: evidence from seismic tomography, Chin. Sci. Bull. 49, 1401-1408; Zhao, D., Maruyama, S., Omori, S., 2007. Mantle dynamics of western Pacific and East Asia: insight from seismic tomography and mineral physics. Gondwana Res. 11, 120-131.] who proposed that the intraplate volcanoes in NE Asia are caused by the back-arc magmatism associated with the deep dehydration process of the subducting slab and convective circulation process in the BMW above the stagnant Pacific slab.

  14. Mount St. Helens Volcano Reawakens: An Overview of the First Month of Activity

    NASA Astrophysics Data System (ADS)

    Gardner, C. A.; Sisson, T.; Scott, W. E.

    2004-12-01

    Late in the evening of 22 September 2004, a shallow (< 2 km), high-frequency earthquake swarm began beneath Mount St. Helens volcano in southwest Washington. Seismicity declined and then, on the afternoon of 25 September and the following day, rapidly increased both in rate and magnitude. This prompted the U.S. Geological Survey's Cascades Volcano Observatory to issue an alert above background level for the first time since the 1980s. Over the following week, maximum earthquake magnitudes increased to M3.5 and the first steam-and-ash emission occurred on 1 October. Four additional steam-and-ash emissions occurred through 5 October; the last and largest sent an ash plume to 15,000 feet. Seismicity then dropped to low levels and changed character to more low-frequency events where it remains as of 24 October. Throughout, earthquake locations have remained shallow. By 30 September, field observers noted localized deformation on the south side of the 1980-86 lava dome and adjacent glacier, but in retrospect the deformation probably began earlier. The volume of the deforming area, or welt, grew to 5.4 million cubic meters by 4 October, grew to 11.7 million cubic meters by 13 October, and continues growing. Gas-sensing flights began on 27 September and detected only a few point sources of magmatic gas over the next several days. By 4 October, however, emission rates for carbon dioxide were large enough to be detected in the plume and by 7 October emissions rates for carbon dioxide, hydrogen sulfide and sulfur dioxide were readily measured. Since 7 October, sulfur dioxide has remained the principal sulfur gas. Forward-Looking InfraRed (FLIR) images from 1 to 10 October recorded increasing, but well below magmatic, temperatures on the northwest flank of the welt. On 11 October, temperature measurements of 500 to 600 degrees C coincided with the appearance of a lava spine on the northwest side of the welt that heralded the beginning of exogenous dome growth. Microbeam

  15. Magma Feeding System of the Past ca. 30-ky Activities of the Zao Volcano, NE Japan

    NASA Astrophysics Data System (ADS)

    Ban, M.; Kotaro, M.; Takebe, Y.; Sato, H.; Sagawa, H.

    2006-12-01

    In the youngest stage (30 ka to present) of the Zao volcano, three active periods (ca. 31 to 29 ka, 7.5 to 4.1 ka, and 2.0 to present) can be observed. Piles of pyroclastic rocks by numerous small to medium sized eruptions are main products of the activities. In this study we examined the magma feeding system in the three periods, based on the petrologic features of the products. Rocks erupted in the three periods are olivine± pyroxene basaltic andesite to andesite, and these were formed by mixing of two end-member magmas, judged from the petrographic and mineralogic features. The estimated felsic end-members are similar among the periods, andesite (ca.60% in silica content) with orthopyroxene (Mg#=ca.64), clinopyroxene (Mg#=ca.68), plagioclase (An=ca.65) phenocrysts. The estimated mafic end-members are basalt with olivine (Fo=ca.80) and plagioclase (An=ca.90) phenocrysts in all periods, however, the bulk MgO, Cr and Ni contents of the erupted rocks are higher in the second period than in the other two periods. During the second and third periods, silica contents of the rocks decreased temporally from 58 to 55-56 % and recovered up to 58 %, and these variations can be explained by the different percentages of the basaltic magma involved in the mixing. Those features are suggesting that the mafic end-member magmas are distinct among periods, and may have been stored in the deeper part of the crust for ca.3.5 to 2.0 ky. Looking at the chemical compositions of rocks in the past ca.0.8-ky eruptions closely, gradual decrease in Zr (and increase in Cr) contents toward upper part can be seen at least twice, which may correspond to the progressive injection of the basaltic magma to the shallower andesitic magma chamber, and it is estimated that the duration of each injection is less than 0.2 ky.

  16. Remotely triggered seismic activity in Hakone volcano during and after the passage of surface waves from the 2011 M9.0 Tohoku-Oki earthquake

    NASA Astrophysics Data System (ADS)

    Yukutake, Yohei; Miyazawa, Masatoshi; Honda, Ryou; Harada, Masatake; Ito, Hiroshi; Sakaue, Minoru; Koketsu, Kazuki; Yoshida, Akio

    2013-07-01

    Immediately after the March 11, 2011, M9.0 Tohoku-Oki earthquake, seismic activity increased remarkably beneath Hakone volcano, central Japan, at an epicentral distance of 450 km. The heightened seismicity was initiated during the passage of the large-amplitude surface waves from the main shock and continued over the subsequent 2 months. We obtained hypocenters and focal mechanisms of the seismic sequence, with the aim of clarifying the physical mechanism responsible for the remotely triggered seismicity. We used data from a dense seismic network containing 56 online permanent and offline temporary stations in and around the Hakone volcano. We found that the earthquakes that occurred during the passage of the surface waves are located at the lower depth limit of ordinary seismicity in the caldera. These earthquakes have larger magnitudes than both the ordinary seismicity prior to the Tohoku-Oki earthquake and the seismicity triggered after the passage of the surface waves. The focal mechanism that we determined is a strike-slip fault type with the P-axis in the NW-SE direction, which is consistent with the focal mechanisms of earthquakes that occurred after the passage of the surface waves and the tectonic stress field in the region. We also tried to detect missing events that occurred immediately after the passage of the surface waves, by using a waveform correlation technique. The detected events are distributed near the hypocenters of the earthquakes that occurred during the passage of the surface waves. The origin times of the first four events after the arrival of surface waves are consistent with the phases of the decrease in normal stress generated by the surface waves. The results suggest that the changes in dynamic stress due to the surface waves from the 2011 Tohoku-Oki earthquake contributed significantly to the initiation of the sequence of triggered seismic activity. Assuming that normal stress changes on the faults did play an important role in the

  17. Characterization of volcanic activity using observations of infrasound, volcanic emissions, and thermal imagery at Karymsky Volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Lopez, T.; Fee, D.; Prata, F.

    2012-04-01

    Karymsky Volcano is one of the most active and dynamic volcanoes in Kamchatka, with activity ranging from vigorous degassing, frequent ash emissions, and apparent vent sealing, all punctuated by daily to weekly explosive magmatic eruptions. Recent studies have highlighted the strengths in using complementary infrasound measurements and remote volcanic emission measurements to characterize volcanic activity, with the potential to discriminate emission-type, approximate ash-cloud height, and estimate SO2 emission mass. Here we use coincident measurements of infrasound, SO2, ash, and thermal radiation collected over a ten day period at Karymsky Volcano in August 2011 to characterize the observed activity and elucidate vent processes. The ultimate goal of this project is to enable different types of volcanic activity to be identified using only infrasound data, which would significantly improve our ability to continuously monitor remote volcanoes. Four types of activity were observed. Type 1 activity is characterized by discrete ash emissions occurring every 1 - 5 minutes that either jet or roil out of the vent, by plumes from 500 - 1500 m (above vent) altitudes, and by impulsive infrasonic onsets. Type 2 activity is characterized by periodic pulses of gas emission, little or no ash, low altitude (100 - 200 m) plumes, and strong audible jetting or roaring. Type 3 activity is characterized by sustained emissions of ash and gas, with multiple pulses lasting from ~1 - 3 minutes, and by plumes from 300 - 1500 m. Type 4 activity is characterized by periods of relatively long duration (~30 minutes to >1 hour) quiescence, no visible plume and weak SO2 emissions at or near the detection limit, followed by an explosive, magmatic eruption, producing ash-rich plumes to >2000 m, and centimeter to meter (or greater) sized pyroclastic bombs that roll down the flanks of the edifice. Eruption onset is accompanied by high-amplitude infrasound and occasionally visible shock

  18. Intense Seismic Activity at Chiles and Cerro Negro Volcanoes on the Colombia-Ecuador Border

    NASA Astrophysics Data System (ADS)

    Torres, R. A.; Cadena, O.; Gomez, D.; Ruiz, M. C.; Prejean, S. G.; Lyons, J. J.; White, R. A.

    2015-12-01

    The region of Chiles and Cerro Negro volcanoes, located on the Colombian-Ecuadorian border, has experienced an ongoing seismic swarm beginning in Aug. 2013. Based on concern for local residents and authorities, a cooperative broadband monitoring network was installed by the Servicio Geológico Colombiano in Colombia and the Instituto Geofísico of the Escuela Politécnica Nacional in Ecuador. Since November 2013 more than 538,000 earthquakes were recorded; although since May 2015 the seismicity has decreased significantly to an average of 70 events per day. Three large earthquake swarms with increasing energy occurred in Aug.-Oct. 2013, March-May 2014, and Sept.-Dec. 2014. By the end of 2014, roughly 400 earthquakes greater than M 3 had occurred with a maximum rate of 8000 earthquakes per day. The largest earthquake was a 5.6 ML on Oct. 20, 2014. This event produced an InSAR coseismic deformation of ~23 cm (S. Ebmeier, personal communication). Most events are typical brittle failure volcano-tectonic (VT) earthquakes that are located in a cluster beneath the southern flank of Chiles volcano, with depths between 1.5 and 10 km. Although the great majority of earthquakes are VT, some low-frequency (LF, ~0.5 Hz) and very-low-frequency (VLF) events have occurred. Particle motion analysis suggests that the VLF source migrated with time. While a VLF on Oct. 15, 2014 was located south of Chiles volcano, near the InSAR source, the VLF registered on Feb. 14, 2015 was likely located very close to Chiles Volcano. We infer that magma intrusion and resulting fluid exsolution at depths greater than 5 km are driving seismicity in the Chiles-Cerro Negro region. However earthquakes are failing in a manner consistent with regional tectonics. Relative relocations reveal a structure consistent with mapped regional faults. Thus seismicity is likely controlled by an interaction of magmatic and tectonic processes. Because the regional stress field is highly compressional and the volcanoes

  19. Melt inclusions in scoria and associated mantle xenoliths of Puy Beaunit Volcano, Chaîne des Puys, Massif Central, France

    NASA Astrophysics Data System (ADS)

    Jannot, Séverine; Schiano, Pierre; Boivin, Pierre

    2005-07-01

    In order to characterize the composition of the parental melts of intracontinental alkali-basalts, we have undertaken a study of melt and fluid inclusions in olivine crystals in basaltic scoria and associated upper mantle nodules from Puy Beaunit, a volcano from the Chaîne des Puys volcanic province of the French Massif Central (West-European Rift system). Certain melt inclusions were experimentally homogenised by heating-stage experiments and analysed to obtain major- and trace-element compositions. In basaltic scoria, olivine-hosted melt inclusions occur as primary isolated inclusions formed during growth of the host phase. Some melt inclusions contain both glass and daughter minerals that formed during closed-system crystallisation of the inclusion and consist mainly of clinopyroxene, plagioclase and rhönite crystals. Experimentally rehomogenised and naturally quenched, glassy inclusions have alkali-basalt compositions (with SiO2 content as low as 42 wt%, MgO>6 wt%, Na2O+K2O>5 wt%, Cl~1,000 3,000 ppm and S~400 2,000 ppm), which are consistent with those expected for the parental magmas of the Chaîne des Puys magmatic suites. Their trace-element signature is characterized by high concentration(s) of LILE and high LREE/HREE ratios, implying an enriched source likely to have incorporated small amounts of recycled sediments. In olivine porphyroclasts of the spinel peridotite nodules, silicate melt inclusions are secondary in nature and form trails along fracture planes. They are generally associated with secondary CO2 fluid inclusions containing coexisting vapour and liquid phases in the same trail. This observation and the existence of multiphase inclusions consisting of silicate glass and CO2-rich fluid suggest the former existence of a CO2-rich silicate melt phase. Unheated glass inclusions have silicic major-element compositions, with normative nepheline and olivine components, ~58 wt% SiO2, ~9 wt% total alkali oxides, <3 wt% FeO and MgO. They also have high

  20. Characterising volcanic activity of Piton de la Fournaise volcano by the spatial distribution of seismic velocity changes

    NASA Astrophysics Data System (ADS)

    Sens-Schoenfelder, C.; Pomponi, E.

    2013-12-01

    We apply Passive Image Interferometry to investigate the seismic noise recorded from October 2009 until December 2011 by 21 stations of the IPGP/OVPF seismic network installed on Piton de la Fournaise volcano within the UnderVolc project. The analyzed period contains three eruptions in 2009 and January 2010, two eruptions plus one dyke intrusion in late 2010, and a seismic crises in 2011. Seismic noise of vertical and horizontal components is cross-correlated to measure velocity changes as apparent stretching of the coda. For some station pairs the apparent velocity changes exceed 1% and a decorrelation of waveforms is observed at the time of volcanic activity. This distorts monitoring results if changes are measured with respect to a global reference. To overcome this we present a method to estimate changes using multiple references that stabilizes the quality of estimated velocity changes. We observe abrupt changes that occur coincident with volcanic events as well as long term transient signals. Using a simple assumption about the spatial sensitivity of our measurements we can map the spatial distribution of velocity changes for selected periods. Comparing these signals with volcanic activity and GPS derived surface deformation we can identify patterns of the velocity changes that appear characteristic for the type of volcanic activity. We can differentiate intrusive processes associated with inflation and increased seismic activity, periods of relaxation without seismicity and eruptions solely based on the velocity signal. This information can help to assess the processes acting in the volcano.

  1. What more have we learned from thermal infrared remote sensing of active volcanoes other than they are hot? (Invited)

    NASA Astrophysics Data System (ADS)

    Ramsey, M.

    2009-12-01

    Thermal infrared (TIR) remote sensing has been used for decades to detect changes in the heat output of active and reawakening volcanoes. The data from these thermally anomalous pixels are commonly used either as a monitoring tool or to calculate parameters such as effusion rate and eruptive style. First and second generation TIR data have been limited in the number of spectral channels and/or the spatial resolution. Two spectral channels with only one km spatial resolution has been the norm and therefore the number of science applications is limited to very large or very hot events. The one TIR channel of the Landsat ETM+ instrument improved the spatial resolution to 60 m, but it was not until the launch of ASTER in late 1999 that orbital TIR spectral resolution increased to five channels at 90 m per pixel. For the first time, the ability existed to capture multispectral emitted radiance from volcanic surfaces, which has allowed the extraction of emissivity as well as temperature. Over the past decade ASTER TIR emissivity data have been examined for a variety of volcanic processes including lava flow emplacement at Kilauea and Kluichevskoi, silicic lava dome composition at Sheveluch, Bezymianny and Mt. St. Helens, low temperature fumaroles emissions at Cerro Negro, and textural changes on the pyroclastic flow deposits at Merapi, Sheveluch and Bezymianny. Thermal-temporal changes at the 90 m scale are still an important monitoring tool for active volcanoes using ASTER TIR data. However, the ability to extract physical parameters such as micron-scale roughness and bulk mineralogy has added tremendously to the science derived from the TIR region. This new information has also presented complications such as the effects of sub-pixel thermal heterogeneities and amorphous glass on the emissivity spectra. If better understood, these complications can provide new insights into the physical state of the volcanic surfaces. Therefore, new data processing algorithms

  2. High-Temperature Hydrothermal Vent Field of Kolumbo Submarine Volcano, Aegean Sea: Site of Active Kuroko-Type Mineralization

    NASA Astrophysics Data System (ADS)

    Sigurdsson, H.; Carey, S.; Alexandri, M.; Vougioukalakis, G.; Croff, K.; Roman, C.; Sakellariou, D.; Anagnostou, C.; Rousakis, G.; Ioakim, C.; Gogou, A.; Ballas, D.; Misaridis, T.; Nomikou, P.

    2006-12-01

    Kolumbo submarine volcano is located 7 km north-east of the island of Santorini in the Hellenic arc (Greece), and comprises one of about twenty submarine cones in a NE-trending rift zone. Kolumbo erupted explosively in 1649-50AD, causing 70 fatalities on Santorini. Kolumbo's crater is 1700 m in diameter, with a crater rim at 10 m below sea level and crater floor at depth of 505 m. Recent marine geological investigations, using ROVs, reveal a very active high-temperature hydrothermal vent field in the northeastern part of the Kolumbo crater floor, about 25,000 m2. Vent chimneys up to 4 m high are vigorously emitting colorless gas plumes up to 10 m high in the water column. Temperatures up to 220oC are recorded in vent fluids. Some vents are in crater- like depressions, containing debris from collapsed extinct chimneys. The entire crater floor of Kolumbo is mantled by a reddish-orange bacterial mat, and bacterial filaments of a variety of colors cling to chimneys in dense clusters. Glassy tunicates and anemones are common in lower-temperature environments on the crater floor. Most chimneys show a high porosity, with a central conduit surrounded by an open and very permeable framework of sulfides and sulfates, aiding fluid flow through the chimney walls. In the sulfate-rich samples, blades of euhedral barite and anhydrite crystals coat the outside of the chimney wall, and layers of barite alternate with sulfide in the interior. The dominant sulfides are pyrite, sphalerite, wurtzite, marcasite and galena. Crusts on extinct and lower-temperature chimneys are composed of amorphous silica, goethite and halite. Sulfur isotope composition of sulfates is virtually at sea water values, whereas the sulfides are more depleted. Elevated levels of copper, gold and silver are observed in bulk composition of chimney samples. Both the structural setting, character of the vent field and sulfide/sulfate mineralogy and geochemistry indicate on-going Kuroko-type mineralization in the

  3. Chronology of Postglacial Eruptive Activity and Calculation of Eruption Probabilities for Medicine Lake Volcano, Northern California

    USGS Publications Warehouse

    Nathenson, Manuel; Donnelly-Nolan, Julie M.; Champion, Duane E.; Lowenstern, Jacob B.

    2007-01-01

    Medicine Lake volcano has had 4 eruptive episodes in its postglacial history (since 13,000 years ago) comprising 16 eruptions. Time intervals between events within the episodes are relatively short, whereas time intervals between the episodes are much longer. An updated radiocarbon chronology for these eruptions is presented that uses paleomagnetic data to constrain the choice of calibrated ages. This chronology is used with exponential, Weibull, and mixed-exponential probability distributions to model the data for time intervals between eruptions. The mixed exponential distribution is the best match to the data and provides estimates for the conditional probability of a future eruption given the time since the last eruption. The probability of an eruption at Medicine Lake volcano in the next year from today is 0.00028.

  4. Subaqueous cryptodome eruption, hydrothermal activity and related seafloor morphologies on the andesitic North Su volcano

    NASA Astrophysics Data System (ADS)

    Thal, Janis; Tivey, Maurice; Yoerger, Dana R.; Bach, Wolfgang

    2016-09-01

    North Su is a double-peaked active andesite submarine volcano located in the eastern Manus Basin of the Bismarck Sea that reaches a depth of 1154 m. It hosts a vigorous and varied hydrothermal system with black and white smoker vents along with several areas of diffuse venting and deposits of native sulfur. Geologic mapping based on ROV observations from 2006 and 2011 combined with morphologic features identified from repeated bathymetric surveys in 2002 and 2011 documents the emplacement of a volcanic cryptodome between 2006 and 2011. We use our observations and rock analyses to interpret an eruption scenario where highly viscous, crystal-rich andesitic magma erupted slowly into the water-saturated, gravel-dominated slope of North Su. An intense fragmentation process produced abundant blocky clasts of a heterogeneous magma (olivine crystals within a rhyolitic groundmass) that only rarely breached through the clastic cover onto the seafloor. Phreatic and phreatomagmatic explosions beneath the seafloor cause mixing of juvenile and pre-existing lithic clasts and produce a volcaniclastic deposit. This volcaniclastic deposit consists of blocky, non-altered clasts next, variably (1-100%) altered clasts, hydrothermal precipitates and crystal fragments. The usually applied parameters to identify juvenile subaqueous lava fragments, i.e. fluidal shape or chilled margin, were not applicable to distinguish between pre-existing non-altered clasts and juvenile clasts. This deposit is updomed during further injection of magma and mechanical disruption. Gas-propelled turbulent clast-recycling causes clasts to develop variably rounded shapes. An abundance of blocky clasts and the lack of clasts typical for the contact of liquid lava with water is interpreted to be the result of a cooled, high-viscosity, crystal-rich magma that failed as a brittle solid upon stress. The high viscosity allows the lava to form blocky and short lobes. The pervasive volcaniclastic cover on North Su is

  5. Satellite relay telemetry in the surveillance of active volcanoes and major fault zones

    NASA Technical Reports Server (NTRS)

    Eaton, J. P.; Ward, P. L.

    1972-01-01

    A review was made of efforts to develop a dense telemetered microearthquake network to study earthquake mechanics along the San Andreas fault and the strain mechanics of the Kilauea Volcano. The principle elements and objectives of the ERTS-A proposal are outlined. Some of the aspects of the earthquake network and the results obtained from it as well as some promising experiments in computerized record processing are discussed.

  6. Rates of volcanic activity along the southwest rift zone of Mauna Loa volcano, Hawaii.

    USGS Publications Warehouse

    Lipman, P.W.

    1981-01-01

    Flow-by-flow mapping of the 65 km long subaerial part of the southwest rift zone and adjacent flanks of Mauna Loa Volcano, Hawaii, and about 50 new 14C dates on charcoal from beneath these flows permit estimates of rates of lava accumulation and volcanic growth over the past 10 000 years. The sequence of historic eruptions along the southwest rift zone, beginning in 1868, shows a general pattern of uprift migration and increasing eruptive volume, culminating in the great 1950 eruption. No event comparable to 1950, in terms of volume or vent length, is evident for at least the previous 1000 years. Rates of lava accumulation along the zone have been subequal to those of Kilauea Volcano during the historic period but they were much lower in late prehistoric time (unpubl. Kilauea data by R. T. Holcomb). Rates of surface covering and volcanic growth have been markedly asymmetric along Mauna Loa's southwest rift zone. Accumulation rates have been about half again as great on the northwest side of the rift zone in comparison with the southeast side. The difference apparently reflects a westward lateral shift of the rift zone of Mauna Loa away from Kilauea Volcano, which may have acted as a barrier to symmetrical growth of the rift zone. -Author

  7. Preliminary radon measurements at Villarrica volcano, Chile

    NASA Astrophysics Data System (ADS)

    Cigolini, C.; Laiolo, M.; Coppola, D.; Ulivieri, G.

    2013-10-01

    We report data from a radon survey conducted at Villarrica volcano. Measurements have been obtained at selected sites by E-PERM® electrets and two automatic stations utilizing DOSEman detectors (SARAD Gmbh). Mean values for Villarrica are 1600 (±1150) Bq/m3 are similar to values recorded at Cerro Negro and Arenal in Central America. Moderately higher emissions, at measurement sites, were recorded on the NNW sector of the volcano and the summit, ranging from 1800 to 2400 Bq/m3. These measurements indicate that this area could potentially be a zone of flank weakness. In addition, the highest radon activities, up to 4600 Bq/m3, were measured at a station located near the intersection of the Liquiñe-Ofqui Fault Zone with the Gastre Fault Zone. To date, the Villarrica radon measurements reported here are, together with those collected at Galeras (Colombia), the sole radon data reported from South American volcanoes. This research may contribute to improving future geochemical monitoring and volcano surveillance.

  8. New constraints on the magmatic system beneath Newberry Volcano from the analysis of active and passive source seismic data, and ambient noise

    NASA Astrophysics Data System (ADS)

    Heath, B.; Toomey, D. R.; Hooft, E. E. E.

    2014-12-01

    Magmatic systems beneath arc-volcanoes are often poorly resolved by seismic imaging due to the small spatial scale and large magnitude of crustal heterogeneity in combination with field experiments that sparsely sample the wavefield. Here we report on our continued analysis of seismic data from a line of densely-spaced (~300 m), three-component seismometers installed on Newberry Volcano in central Oregon for ~3 weeks; the array recorded an explosive shot, ~20 teleseismic events, and ambient noise. By jointly inverting both active and passive-source travel time data, the resulting tomographic image reveals a more detailed view of the presumed rhyolitic magma chamber at ~3-5 km depth, previously imaged by Achauer et al. (1988) and Beachly et al. (2012). The magma chamber is elongated perpendicular to the trend of extensional faulting and encircled by hypocenters of small (M < 2) earthquakes located by PNSN. We also model teleseismic waveforms using a 2-D synthetic seismogram code to recreate anomalous amplitudes observed in the P-wave coda for sites within the caldera. Autocorrelation of ambient noise data also reveals large amplitude waveforms for a small but spatially grouped set of stations, also located within the caldera. On the basis of these noise observations and 2-D synthetic models, which both require slow seismic speeds at depth, we conclude that our tomographic model underestimates low-velocity anomalies associated with the inferred crustal magma chamber; this is due in large part to wavefront healing, which reduces observed travel time anomalies, and regularization constraints, which minimize model perturbations. Only by using various methods that interrogate different aspects of the seismic data are we able to more realistically constrain the complicated, heterogeneous volcanic system. In particular, modeling of waveform characteristics provides a better measure of the spatial scale and magnitude of crustal velocities near magmatic systems.

  9. Remote sensing of volcanos and volcanic terrains

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, Peter J.; Francis, Peter W.; Wilson, Lionel; Pieri, David C.; Self, Stephen; Rose, William I.; Wood, Charles A.

    1989-01-01

    The possibility of using remote sensing to monitor potentially dangerous volcanoes is discussed. Thermal studies of active volcanoes are considered along with using weather satellites to track eruption plumes and radar measurements to study lava flow morphology and topography. The planned use of orbiting platforms to study emissions from volcanoes and the rate of change of volcanic landforms is considered.

  10. Seismic Structure Beneath Taal Volcano, Philippines

    NASA Astrophysics Data System (ADS)

    You, S. H.; Gung, Y.; Konstantinou, K. I.; Lin, C. H.

    2014-12-01

    The very active Taal Volcano is situated 60 km south of Metro Manila in the southern part of Luzon Island. Based on its frequent explosive eruptions and high potential hazards to nearby population of several million, Taal Volcano is chosen as one of the 15 most dangerous "Decade Volcanoes" in the world. We deployed a temporary seismic network consisting of 8 stations since March 2008. The temporal network was operated from late March 2008 to mid March 2010 and recorded over 2270 local earthquakes. In the early data processing stages, unexpected linear drifting of clock time was clearly identified from ambient noise cross-correlation functions for a number of stations. The drifting rates of all problematic stations were determined as references to correct timing errors prior to further processing. Initial locations of earthquakes were determined from manually picking P- and S-phases arrivals with a general velocity model based on AK135. We used travel times of 305 well-located local events to derive a minimum 1-D model using VELEST. Two major earthquake groups were noticed from refined locations. One was underneath the western shore of Taal Lake with a linear feature, and the other spread at shallower depths showing a less compact feature around the eastern flank of Taal Volcano Island. We performed seismic tomography to image the 3D structure beneath Taal Volcano using a well-established algorithm, LOTOS. Some interesting features are noted in the tomographic results, such as a probable solidified past magma conduit below the northwestern corner of Taal Volcano Island, characterized by high Vp, Vs, and low Vp/Vs ratio, and a potential large hydrothermal reservoir beneath the central of Taal Volcano Island, characterized by low Vs and high Vp/Vs ratio. Combining the results of seismicity and tomographic images, we also suggest the potential existence of a magma chamber beneath the southwestern Taal Lake, and a magma conduit or fault extending from there to the

  11. A subsurface structure change associated with the eruptive activity at Sakurajima Volcano, Japan, inferred from an accurately controlled source

    NASA Astrophysics Data System (ADS)

    Maeda, Yuta; Yamaoka, Koshun; Miyamachi, Hiroki; Watanabe, Toshiki; Kunitomo, Takahiro; Ikuta, Ryoya; Yakiwara, Hiroshi; Iguchi, Masato

    2015-07-01

    Temporal variations of Green functions associated with the eruptive activity at Sakurajima Volcano, Japan, were estimated using an accurately controlled routinely operated signal system (ACROSS). We deconvolved 400 s waveforms of the ACROSS signal at nearby stations by a known source time function and stacked the results based on the time relative to individual eruptions and the eruption intervals; the quantities obtained by this procedure are Green functions corresponding to various stages of the eruptive activity. We found an energy decrease in the later phase of the Green functions in active eruptive periods. This energy decrease, localized in the 2-6 s window of the Green functions, is difficult to explain by contamination from volcanic earthquakes and tremors. The decrease could be more reasonably attributed to a subsurface structure change caused by the volcanic activity.

  12. Renalase regulates peripheral and central dopaminergic activities

    PubMed Central

    Serrão, Maria Paula; Soares-Silva, Isabel; Fernandes-Cerqueira, Cátia; Simões-Silva, Liliana; Pinho, Maria João; Remião, Fernando; Sampaio-Maia, Benedita; Desir, Gary V.; Pestana, Manuel

    2014-01-01

    Renalase is a recently identified FAD/NADH-dependent amine oxidase mainly expressed in kidney that is secreted into blood and urine where it was suggested to metabolize catecholamines. The present study evaluated central and peripheral dopaminergic activities in the renalase knockout (KO) mouse model and examined the changes induced by recombinant renalase (RR) administration on plasma and urine catecholamine levels. Compared with wild-type (WT) mice, KO mice presented increased plasma levels of epinephrine (Epi), norepinephrine (NE), and dopamine (DA) that were accompanied by increases in the urinary excretion of Epi, NE, DA. In addition, the KO mice presented an increase in urinary DA-to-l-3,4-dihydroxyphenylalanine (l-DOPA) ratios without changes in renal tubular aromatic-l-amino acid decarboxylase (AADC) activity. By contrast, the in vivo administration of RR (1.5 mg/kg sc) to KO mice was accompanied by significant decreases in plasma levels of Epi, DA, and l-DOPA as well as in urinary excretion of Epi, DA, and DA-to-l-DOPA ratios notwithstanding the accompanied increase in renal AADC activity. In addition, the increase in renal DA output observed in renalase KO mice was accompanied by an increase in the expression of the L-type amino acid transporter like (LAT) 1 that is reversed by the administration of RR in these animals. These results suggest that the overexpression of LAT1 in the renal cortex of the renalase KO mice might contribute to the enhanced l-DOPA availability/uptake and consequently to the activation of the renal dopaminergic system in the presence of renalase deficiency. PMID:25411385

  13. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Expedition Five crew members aboard the International Space Station (ISS) captured this overhead look at the smoke and ash regurgitated from the erupting volcano Mt. Etna on the island of Sicily, Italy in October 2002. Triggered by a series of earthquakes on October 27, 2002, this eruption was one of Etna's most vigorous in years. This image shows the ash plume curving out toward the horizon. The lighter-colored plumes down slope and north of the summit seen in this frame are produced by forest fires set by flowing lava. At an elevation of 10,990 feet (3,350 m), the summit of the Mt. Etna volcano, one of the most active and most studied volcanoes in the world, has been active for a half-million years and has erupted hundreds of times in recorded history.

  14. Internal structure of Erebus volcano, Antarctica imaged by high-resolution active-source seismic tomography and coda interferometry

    NASA Astrophysics Data System (ADS)

    Zandomeneghi, D.; Aster, R.; Kyle, P.; Barclay, A.; Chaput, J.; Knox, H.

    2013-03-01

    Erebus volcano, Antarctica has hosted a persistent convecting phonolite lava lake for over 40 years. The lake produces small (VEI 0-1) Strombolian eruptions resulting from gas slugs rising through the upper conduit system. High-resolution (to scale lengths of several hundreds of meters) three-dimensional P-wave tomographic velocity images were obtained to a depth of approximately 600 m below the volcano surface. Data were collected using 91 seismographs deployed over an approximately 4 by 4 km area of the summit region. Seismic illumination was provided by 12 chemical shots emplaced in shallow snow and ice boreholes. P-wave direct arrival travel-time measurements were used to invert for strong velocity anomalies (with spatial variations in Vp exceeding ±1 km/s) associated with the uppermost few km. Shallow anomalies correlate with fumarolic ice caves, a prominent radial chilled dike, and ring structures associated with the caldera rim. Conduit structures feeding the lava lake and other vents within the Inner Crater are evidently too small (e.g., less than many 10 s of meters) to be imaged under the resolution limits of this experiment. However, combined velocity and coda interferometry scattering intensity images identify near-summit regions with both low velocity and high scattering that are candidates for magma accommodation. Results indicate a nonaxisymmetric near-summit magmatic system that is likely constrained by heterogeneous structures in the uppermost volcano. The most extensive volume of near-summit magma likely resides approximately 500 m NW of the active Inner Crater vents at depths of 500 m and more below the surface.

  15. Magmatic inflation at a dormant stratovolcano: 1996-1998 activity at Mount Peulik volcano, Alaska, revealed by satellite radar interferometry

    USGS Publications Warehouse

    Lu, Zhiming; Wicks, C., Jr.; Dzurisin, D.; Power, J.A.; Moran, S.C.; Thatcher, W.

    2002-01-01

    A series of ERS radar interferograms that collectively span the time interval from July 1992 to August 2000 reveal that a presumed magma body located 6.6 ??? 0.5 km beneath the southwest flank of the Mount Peulik volcano inflated 0.051 ??? 0.005 km3 between October 1996 and September 1998. Peulik has been active only twice during historical time, in 1814 and 1852, and the volcano was otherwise quiescent during the 1990s. The inflation episode spanned at least several months because separate interferograms show that the associated ground deformation was progressive. The average inflation rate of the magma body was ???0.003 km3/month from October 1996 to September 1997, peaked at 0.005 km3/month from 26 June to 9 October 1997, and dropped to ???0.001 km3/month from October 1997 to September 1998. An intense earthquake swarm, including three ML 4.8 - 5.2 events, began on 8 May 1998 near Becharof Lake, ???30 km northwest of Peulik. More than 400 earthquakes with a cumulative moment of 7.15 ?? 1017 N m were recorded in the area through 19 October 1998. Although the inflation and earthquake swarm occured at about the same time, the static stress changes that we calculated in the epicentral area due to inflation beneath Peulik appear too small to provide a causal link. The 1996-1998 inflation episode at Peulik confirms that satellite radar interferometry can be used to detect magma accumulation beneath dormant volcanoes at least several months before other signs of unrest are apparent. This application represents a first step toward understanding the eruption cycle at Peulik and other stratovolcanoes with characteristically long repose periods.

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

    PubMed Central

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

    2013-01-01

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

  17. Earthquakes and Volcanic Processes at San Miguel Volcano, El Salvador, Determined from a Small, Temporary Seismic Network

    NASA Astrophysics Data System (ADS)

    Hernandez, S.; Schiek, C. G.; Zeiler, C. P.; Velasco, A. A.; Hurtado, J. M.

    2008-12-01

    The San Miguel volcano lies within the Central American volcanic chain in eastern El Salvador. The volcano has experienced at least 29 eruptions with Volcano Explosivity Index (VEI) of 2. Since 1970, however, eruptions have decreased in intensity to an average of VEI 1, with the most recent eruption occurring in 2002. Eruptions at San Miguel volcano consist mostly of central vent and phreatic eruptions. A critical challenge related to the explosive nature of this volcano is to understand the relationships between precursory surface deformation, earthquake activity, and volcanic activity. In this project, we seek to determine sub-surface structures within and near the volcano, relate the local deformation to these structures, and better understand the hazard that the volcano presents in the region. To accomplish these goals, we deployed a six station, broadband seismic network around San Miguel volcano in collaboration with researchers from Servicio Nacional de Estudios Territoriales (SNET). This network operated continuously from 23 March 2007 to 15 January 2008 and had a high data recovery rate. The data were processed to determine earthquake locations, magnitudes, and, for some of the larger events, focal mechanisms. We obtained high precision locations using a double-difference approach and identified at least 25 events near the volcano. Ongoing analysis will seek to identify earthquake types (e.g., long period, tectonic, and hybrid events) that occurred in the vicinity of San Miguel volcano. These results will be combined with radar interferometric measurements of surface deformation in order to determine the relationship between surface and subsurface processes at the volcano.

  18. Spreading Volcanoes

    NASA Astrophysics Data System (ADS)

    Borgia, Andrea; Delaney, Paul T.; Denlinger, Roger P.

    As volcanoes grow, they become ever heavier. Unlike mountains exhumed by erosion of rocks that generally were lithified at depth, volcanoes typically are built of poorly consolidated rocks that may be further weakened by hydrothermal alteration. The substrates upon which volcanoes rest, moreover, are often sediments lithified by no more than the weight of the volcanic overburden. It is not surprising, therefore, that volcanic deformation includes-and in the long term is often dominated by-spreading motions that translate subsidence near volcanic summits to outward horizontal displacements around the flanks and peripheries. We review examples of volcanic spreading and go on to derive approximate expressions for the time volcanoes require to deform by spreading on weak substrates. We also demonstrate that shear stresses that drive low-angle thrust faulting from beneath volcanic constructs have maxima at volcanic peripheries, just where such faults are seen to emerge. Finally, we establish a theoretical basis for experimentally derived scalings that delineate volcanoes that spread from those that do not.

  19. Spreading volcanoes

    USGS Publications Warehouse

    Borgia, A.; Delaney, P.T.; Denlinger, R.P.

    2000-01-01

    As volcanoes grow, they become ever heavier. Unlike mountains exhumed by erosion of rocks that generally were lithified at depth, volcanoes typically are built of poorly consolidated rocks that may be further weakened by hydrothermal alteration. The substrates upon which volcanoes rest, moreover, are often sediments lithified by no more than the weight of the volcanic overburden. It is not surprising, therefore, that volcanic deformation includes-and in the long term is often dominated by-spreading motions that translate subsidence near volcanic summits to outward horizontal displacements around the flanks and peripheries. We review examples of volcanic spreading and go on to derive approximate expressions for the time volcanoes require to deform by spreading on weak substrates. We also demonstrate that shear stresses that drive low-angle thrust faulting from beneath volcanic constructs have maxima at volcanic peripheries, just where such faults are seen to emerge. Finally, we establish a theoretical basis for experimentally derived scalings that delineate volcanoes that spread from those that do not.

  20. Mineralogical and Sulfur Isotopic Study on Volcanic Ash of the 2014 Eruption at Ontake Volcano, Central Honshu, Japan

    NASA Astrophysics Data System (ADS)

    Imura, T.; Minami, Y.; Ohba, T.; Takahashi, R.; Imai, A.; Hayashi, S.

    2015-12-01

    Ontake volcano erupted on 27th September 2014. Components in fallout samples were analyzed with microscope, XRD, and SEM-EDS. Pyrophyllite, smectite, muscovite, kaoline group minerals, quartz, cristobalite, tridymite, pyrite, alunite, gypsum and anhydrite were identified from bulk samples. Coarse ash fraction (> 125 µm) consists mainly of siliceous fragments that are intensely altered and contain pyrite and rutile. Weakly-altered dark-gray volcanic rock fragments are also contained. Fine fraction is abundant in euhedral free crystals of alunite and gypsum and aggregates of silica minerals. The 34S/32S ratios of bulk ash samples were analyzed for sulfur leached by water (water-soluble sulfate), gastric (HCl-soluble sulfate), and HNO3 (sulfide). Gastric and HNO3 leaching methods were applied to coarse fraction too. The bulk δ34SCDT compositions of water-soluble sulfate, HCl-soluble sulfate and sulfide were +14.7 ‰, +15.7 ‰, and -4.7 ‰, respectively. Those of HCl-soluble sulfate and sulfide in coarse fraction were +9.1 ‰ and -4.3 ‰, respectively. Paragenesis of quartz and pyrophyllite in single grain implies hydrothermal alteration by hot (> 230 °C), acidic fluid in the sub-volcanic system. The sulfur isotope geothermometry (Ohmoto and Rye, 1979) applied to the pair of water-soluble sulfate and bulk sulfide resulted in 306 °C. Similar temperature (ca. 296 °C) was estimated for the pair of HCl-soluble sulfate and sulfide in bulk ash. The mineralogy and sulfur isotopic study indicate that the 2014 Ontake eruption was derived from an acidic high-temperature (ca. 300 °C) sub-volcanic hydrothermal fluid. However, the estimated temperature for the pair of HCl-soluble sulfate and sulfide from coarse fraction resulted in higher temperature (ca. 482 °C). The coarse fraction preserved the past temperature record of the hydrothermal fluid, because the coarse lithic fragments were derived from pre-existing altered rocks.

  1. First 3D thermal mapping of an active volcano using an advanced photogrammetric method

    NASA Astrophysics Data System (ADS)

    Antoine, Raphael; Baratoux, David; Lacogne, Julien; Lopez, Teodolina; Fauchard, Cyrille; Bretar, Frédéric; Arab-Sedze, Mélanie; Staudacher, Thomas; Jacquemoud, Stéphane; Pierrot-Deseilligny, Marc

    2014-05-01

    to extract 3D informations from thermal images taken from different positions. This paper presents the first 3D thermal map of an active volcano (Piton de la Fournaise, La Réunion Island) directly generated from 70 thermal images (so-called "stereothermogrammetric" DEM). The data were obtained above Dolomieu caldera by helicopter just before sunrise, during a clear weather in 2008. They were obtained before the eruptive events occurring within the Dolomieu caldera. We used a 28 mm focal FLIR Thermacam PM695 lent by the Piton de la Fournaise Observatory. The thermal images were acquired automatically every 30 seconds with the helicopter flying around the caldera at low altitude (less than 100 m height above the caldera). This survey led to the acquisition of images with a ground pixel size in the range of 1-3 m. A particular attention has been brought to the obtaining of a high overlap percentage (80 percents) for the localization of the maximum tie points on the image. Finally, the acquisition of 70 images allowed the generation of a 3D thermal model of the caldera containing more than 500000 points. i.e. 1 point each 2 m², considering a surface of 106 m² for the Dolomieu caldera. This model is then compared with a DEM recently obtained with the LIDAR method after the eruptive events occurring within Dolomieu. The comparison of these independent methods leads to the validation of the stereothermogrammetric method. It allows the quantification of the thickness of the lava flows within the Dolomieu collapse in 2008 and 2009, i.e. approximately 80 meters, as estimated by previous studies from field observations.

  2. Continuous, Long-term, Cyclic, Varied Eruptive Activity Observed at NW Rota-1 Submarine Volcano, Mariana Arc

    NASA Astrophysics Data System (ADS)

    Chadwick, B.; Dziak, R. P.; Baker, E. T.; Cashman, K. V.; Embley, R. W.; Ferrini, V.; de Ronde, C. E.; Butterfield, D. A.; Deardorff, N.; Haxel, J. H.; Matsumoto, H.; Fowler, M. J.; Walker, S. L.; Bobbitt, A. M.; Merle, S. G.

    2009-12-01

    NW Rota-1 is a conical, basaltic-andesite submarine volcano in the Mariana arc with a summit depth of 520 m. Eruptive activity was first witnessed here during remotely operated vehicle (ROV) dives in 2004, and was also observed during all four subsequent ROV expeditions in 2005, 2006, and 2009. Cyclic explosive bursts were documented by a portable hydrophone during the 2006 ROV dives. More recently, a year of instrumental monitoring data from a moored hydrophone and plume sensor show that the volcano was continuously active from February 2008 to February 2009, and that the cyclic character of the eruptions occurred with variable intensity and periodicity. The 2008-2009 hydrophone record includes explosive bursts every 1-2 minutes, with high acoustic amplitudes in the first half of the year and lower more variable amplitudes in the second half. In contrast, the moored turbidity sensor recorded major eruptive plumes on a time scale of every few days to weeks, and at approximately the same frequency throughout the year. This apparent disparity may be explained by the most recent ROV and portable hydrophone observations at NW Rota-1 in April 2009, which confirmed continuous and diverse eruptive activity with cyclicity over several time scales, from minutes to days. Visual observations at the eruptive vent provided new insight into the process of very slow lava extrusion on the seafloor. During slow extrusion (at rates of 1-2 m3/hr), lava spines rose in the eruptive vent, then gradually disintegrated into angular blocks as they cooled and were shoved aside by the next lava to emerge. Freshly erupted lava blocks periodically tumbled down the sides of a growing cone (40-m high and 300-m wide) that had been constructed by this process since the last visit in 2006. Thus auto-brecciation during slow lava extrusion underwater produces primary deposits that could easily be mistaken as secondary, and can construct substantial landforms on submarine arc volcanoes. Even during

  3. Permafrost and Periglacial Activity Distribution and Geothermal Anomalies in the Chachani and El Misti Volcanoes (Southern Peru)

    NASA Astrophysics Data System (ADS)

    Palacios, D.; Andrés, N.; Úbeda, J.; Alcalá, J.

    2009-04-01

    The El Misti volcano (16˚ 17′ S, 71˚ 24′ W, 5.822 m) is considered one of the most potentially catastrophic in America. Its crater is 18 km from the centre of Arequipa (2335 m a.s.l.), a city with more than 800,000 inhabitants whose population has doubled over the last 20 years, spreading out over the volcano's sides and gullies in many new settlements, less than 12 km away from the crater. Although the last significant eruptive period occurred in 2300-2050 BP, during the last five thousand years the recurrence period for eruptions has been 500 to 1500 years (Thouret et al. 2001). The last eruption occurred between 1440 and 1447 AD, although it was low-intensity. The crater currently has fumarolic activity. The volcano does not show any signs of having supported glaciers or any periglacial form in the past. The Chachani volcanic complex (16˚ 11' S 71˚ 31' W, 6.057 m a.s.l.) lies 18 km northeast of El Misti and 22 km from the centre of the city of Arequipa. The complex is made up of several volcanic cones and domes. The date of the most recent eruption is unknown, and no current or recent eruptive activity has been recorded or detected (Paquereau et al. 2006). The complex probably supported glaciers during the Little Ice Age, although there are none at present. Geomorphological evidence shows that glaciers during the Last Glacial Maximum were very extensive, with some of their feet reaching an altitude of 4000m. Rocky glaciers up to 1800 m long can be found inside some of the cirques. The PichuPichi Complex (16° 25' 25"S 71°14'27", 5650 m a.s.l.), 22 km E of El Misti, supported substantial glaciers during the Last Glacial Maximum, with a minimum foot altitude of c.4000 m, and like the Chachani, has numerous rock glacier formations in its cirques. The aim of this paper is to ascertain whether the lack of glacial or periglacial geomorphological evidence on the El Misti volcano is due to its destruction from subsequent volcanic activity, or

  4. A study of the Taisho lahar generated by the 1926 eruption of Tokachidake Volcano, central Hokkaido, Japan, and implications for the generation of cohesive lahars

    NASA Astrophysics Data System (ADS)

    Uesawa, Shimpei

    2014-01-01

    Understanding the generation mechanisms of lahars is important for improving volcanic hazard assessments. The Taisho lahar (TL) was generated during the 1926 eruption of Tokachidake Volcano, Japan, and was considered a typical snowmelt lahar caused by the runout of hot debris onto a snow-covered slope. A similar mechanism produced a huge mud flow during the 1985 eruption of Nevado del Ruiz, Colombia. However, the origin of water in such lahars remains a controversial topic because the calculated water mass is based on the assumption that all of the snow on the runout area of the TL was melted, although this is much less than the estimated water volume in the TL estimated by previous studies. I have re-examined proximal deposits of the TL and their paleomagnetic characteristics in order to better understand the eruption sequence and formation of the TL. The TL produced two debris avalanche deposits and a surge-like deposit that had relatively high emplacement temperature (~ 350 °C). The deposits are composed of hydrothermally altered andesitic gravel, sand and mud. The high clay content (3-5 wt.% clay in the < 2 mm fraction) and sedimentary characteristics indicate that the flow was a cohesive lahar, most likely induced by collapse of a hydrothermally altered pyroclastic cone (hypocenter). The presence of the surge deposit indicates that the TL was not caused by simple collapse of a cinder cone but by a phreatic explosion that resulted in sector collapse. This suggests that the hydrothermal system was related to the 1926 eruption. The present-day volcano has a large hydrothermal system (1 × 106 m3 water) beneath the active crater. This study indicates that hydrothermal system explosions can trigger cohesive lahars that contain both snow melt and hydrothermal pore water, and this indicates the need to monitor hydrothermal systems.

  5. Eruptive viscosity and volcano morphology

    NASA Technical Reports Server (NTRS)

    Posin, Seth B.; Greeley, Ronald

    1988-01-01

    Terrestrial central volcanoes formed predominantly from lava flows were classified as shields, stratovolcanoes, and domes. Shield volcanoes tend to be large in areal extent, have convex slopes, and are characterized by their resemblance to inverted hellenic war shields. Stratovolcanoes have concave slopes, whereas domes are smaller and have gentle convex slopes near the vent that increase near the perimeter. In addition to these differences in morphology, several other variations were observed. The most important is composition: shield volcanoes tend to be basaltic, stratovolcanoes tend to be andesitic, and domes tend to be dacitic. However, important exceptions include Fuji, Pico, Mayon, Izalco, and Fuego which have stratovolcano morphologies but are composed of basaltic lavas. Similarly, Ribkwo is a Kenyan shield volcano composed of trachyte and Suswa and Kilombe are shields composed of phonolite. These exceptions indicate that eruptive conditions, rather than composition, may be the primary factors that determine volcano morphology. The objective of this study is to determine the relationships, if any, between eruptive conditions (viscosity, erupted volume, and effusion rate) and effusive volcano morphology. Moreover, it is the goal of this study to incorporate these relationships into a model to predict the eruptive conditions of extraterrestrial (Martian) volcanoes based on their morphology.

  6. Chilean Volcanoes

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On the border between Chile and the Catamarca province of Argentina lies a vast field of currently dormant volcanoes. Over time, these volcanoes have laid down a crust of magma roughly 2 miles (3.5 km) thick. It is tinged with a patina of various colors that can indicate both the age and mineral content of the original lava flows. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on May 15, 1999. This is a false-color composite image made using shortwave infrared, infrared, and green wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  7. Geochemistry and Sr-Nd isotopic compositions of mantle xenoliths from the Monte Vulture carbonatite-melilitite volcano, central southern Italy

    NASA Astrophysics Data System (ADS)

    Downes, H.; Kostoula, T.; Jones, A. P.; Beard, A. D.; Thirlwall, M. F.; Bodinier, J.-L.

    2002-08-01

    Spinel peridotite xenoliths found in the Monte Vulture carbonatite-melilitite volcano have been derived from the subcontinental lithospheric mantle beneath central southern Italy. Clinopyroxene-poor lherzolites and harzburgites are the most common rock types, with subordinate wehrlites and dunites. Small quantities of phlogopite and carbonate are present in a few samples. The peridotites record a large degree of partial melting and have experienced subsequent enrichment which has increased their LILE and LREE contents, but in most cases their HFSE contents are low. Despite being carried to the surface by a carbonatite-melilitite host, the whole-rock and clinopyroxene compositions of the xenoliths have a trace-element signature more closely resembling that of silicate-melt metasomatised mantle rather than carbonatite-metasomatised peridotites. 87Sr/86Sr and 143Nd/144Nd isotopic ratios for clinopyroxene from the Vulture peridotites are 0.7042-0.7058 and 0.51260-0.5131 respectively. They form a trend away from the depleted mantle to the composition of the host magmas, and show a significant enrichment in 87Sr/86Sr compared with most European mantle samples. The mantle beneath Monte Vulture has had a complex evolution - we propose that the lithosphere had already undergone extensive partial melting before being affected by metasomatism from a silicate melt which may have been subduction-related.

  8. SO2 Emission from Active Volcanoes Measured Simultaneously by COSPEC and mini-DOAS

    NASA Astrophysics Data System (ADS)

    Barrancos, José; Roselló, José I.; Calvo, David; Padrón, Eleazar; Melián, Gladys; Hernández, Pedro A.; Pérez, Nemesio M.; Millán, Millán M.; Galle, Bo

    2008-01-01

    We measured SO2 emission rate from six volcanoes in Latin America (Santa Ana, El Salvador; San Cristóbal and Masaya, Nicaragua; Arenal and Poás, Costa Rica; Tungurahua and Sierra Negra, Ecuador) and from Mt. Etna, Italy, using two different remote sensing techniques: COSPEC (COrrelation SPECtrometer) and miniDOAS (miniaturized Differential Optical Absorption Spectroscopy). One of the goals of this study was to evaluate the differences in SO2 emission rates obtained by these two methods. The observed average SO2 emission rates measured during this study were 2688 t· d -1 from Tungurahua in July 2006, 2375 t· d -1 in September 2005 and 480 t· d -1 in February 2006 from Santa Ana, 1200 t· d -1 in May 2005 from Etna, 955 t· d -1 in March 2006 and 1165 t· d -1 in December 2006 from Masaya, 5400 t· d -1 of March 7, 2006 and 265 t· d -1 in March 2006 from San Cristobal, 113 t· d -1 in April 2006 from Arenal, 104 t· d -1 in April 2006 from Poás and 11 t· d -1 in July 2006 from Sierra Negra volcano. Most of the observed relative differences of SO2 emission measurements from COSPEC and miniDOAS were lower than 10%.

  9. Volcanoes of the Solar System

    NASA Astrophysics Data System (ADS)

    Frankel, Charles

    1996-09-01

    Nothing can be more breathtaking than the spectacle of a volcano erupting. Space-age lunar and planetary missions offer us an unprecedented perspective on volcanism. Starting with the Earth, Volcanoes of the Solar System takes the reader on a guided tour of the terrestrial planets and moons and their volcanic features. We see lunar lava fields through the eyes of the Apollo astronauts, and take an imaginary hike up the Martian slopes of Olympus Mons--the tallest volcano in the solar system. Complemented by over 150 photographs, this comprehensive and lucid account of volcanoes describes the most recent data on the unique and varied volcanic features of Venus and updates our knowledge on the prodigiously active volcanoes of Io. A member of the Association of European Volcanologists, Charles Frankel has directed documentary films on geology, astronomy and space exploration and has authored a number of articles on the earth sciences.

  10. SO2 degassing at Tungurahua volcano (Ecuador) between 2007 and 2013: Transition from continuous to episodic activity

    NASA Astrophysics Data System (ADS)

    Hidalgo, Silvana; Battaglia, Jean; Arellano, Santiago; Steele, Alexander; Bernard, Benjamin; Bourquin, Julie; Galle, Bo; Arrais, Santiago; Vásconez, Freddy

    2015-06-01

    We present continuous SO2 measurements performed at Tungurahua volcano with a permanent network of 4 scanning DOAS instruments between 2007 and 2013. The volcano has been erupting since September 1999, but on the contrary to the first years of eruption when the activity was quasi-continuous, the activity transitioned in late 2008 towards the occurrence of distinct eruptive phases separated by periods of quiescence. During our study period we distinguish 11 phases lasting from 17 to 527 days separated by quiescence periods of 26 to 184 days. We propose a new routine to quantify the SO2 emissions when data from a dense DOAS monitoring network are available. This routine consists in summing all the highest validated SO2 measurements among all stations during the 10 h of daily working-time to obtain a daily observed SO2 mass. Since measurement time is constant at Tungurahua the "observed" amounts can be expressed in tons per 10 h and can easily be converted to a daily average flux or mass per day. Our results provide time series having an improved correlation on a long time scale with the eruptive phases and with quiescence periods. A total of 1.25 Mt (1.25 × 109 kg) of SO2 has been released by Tungurahua during the study period, with 95% of these emissions occurring during phases of activity and only 5% during quiescence. This shows a contrast with previous volcanic behaviour when passive degassing dominated the total SO2 emissions. SO2 average daily mass emission rates are of 73 ± 56 t/d during quiescent periods, 735 ± 969 t/d during long-lasting phases and 1424 ± 1224 t/d during short-lasting phases. Degassing during the different eruptive phases displays variable patterns. However, two contrasting behaviours can be distinguished for the onset of eruptive phases with both sudden and progressive onsets being observed. The first is characterised by violent opening of the conduit by high energy Vulcanian explosions; and the second by a progressive, in crescendo

  11. Social vulnerability as a contributing factor to disasters in Central America: A case study at San Vicente volcano, El Salvador

    NASA Astrophysics Data System (ADS)

    Bowman, L. J.; Henquinet, K. B.; Gierke, J. S.; Rose, W. I.

    2012-12-01

    El Salvador's geographic location on the Pacific Ring of Fire at the juncture of the Caribbean and Cocos plates exposes its population to various natural hazards, including volcanic eruptions (e.g., Santa Ana in 2005), earthquakes (e.g., January 13 and February 13, 2001), and landslides and flooding due to tropical rainfall events (e.g., Hurricane Mitch in 1998, Hurricane Stan in 2005). Such hazards can be devastating anywhere, but the condition of social vulnerability in which many Salvadorans currently live exacerbates the impacts of these hazards. Aspects contributing to most rural Salvadorans being marginalized include a colonial history marked by ethnic discrimination and laws prohibiting land ownership, lack of access to desirable land in an agrarian society, a poor education system, global economic policies that foster inequality, political marginalization, a bloody civil conflict, and rampant criminality and violence. In November 2009, an extreme rainfall event triggered landslides and lahars killing over 200 people at San Vicente volcano. This disaster brought to light weaknesses in disaster preparedness and response plans. Despite the existence of recent hazard maps and lahar inundation models (2001), and the occurrence of a similar, deadly event in 1934, the population appeared to be unaware of the risk, and lacked the organization and decision-making protocols to adequately deal with the emergency. Therefore, in the aftermath of the 2009 lahars, much of the focus on disaster risk reduction (DRR) initiatives has been aimed at the communities affected by this most recent event. Our study examines root causes of social vulnerability and assesses the apparent impacts of these interventions on the population, including individual's perceptions regarding these risk-reducing interventions. Two years after the event, though aid abounds, many people remain vulnerable to hazards in this area. Semi-structured interviews were completed with survivors of the 2009

  12. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

    ... of which are so thick that they block the penetration of light from CALIPSO's lidar to the surface. The yellow layer near the surface over France is believed to be primarily air pollution, but could also contain ash from the volcano. Highlighting its ...

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  14. High resolution deformation measurements at active volcanoes: a new remote sensing technology

    NASA Astrophysics Data System (ADS)

    Hort, M. K.; Scharff, L.; Gerst, A.; Meier, K.; Falk, S.; Peters, G.; Ripepe, M.

    2013-12-01

    It is known from observations at different volcanoes using ULP seismic observations that the volcanic edifice deforms slightly prior to an eruption. It can be expected that immediately prior to an eruption the largest deformation should occur in the vicinity of the vent. However, placing instruments at the vent is impossible as they will be destroyed during an eruption. Here we present new, high temporal resolution (up to 300Hz) deformation measurement that utilizes the phase information of a frequency modulated Doppler radar system. We decompose the Doppler signal into two parts, one part which allows us to measure speeds significantly above 0.5m/s (i.e. the movement of volcanic ash and clasts). The other part utilizes the slow phase changes of the signal reflected from non-moving objects, i.e. the volcanic edifice. This signal is used to measure very slow and longer term deformations, which are the main subject of this study. The method has been tested measuring the displacement of high rise buildings during strong winds. It can be shown that displacements down to 50 μm can be resolved without a problem. We apply this method to different data sets collected at Stromboli volcano, Italy, as well as Santiaguito volcano, Guatemala. At Stromboli we observed the NE crater once in 2008 and once in 2011. During both campaigns we observe on average a displacement between 1 and 5mm before different eruptions. This displacement can be interpreted as a widening of the conduit prior to an eruption. In a couple of cases even an oscillatory movement is observed with frequencies of about 0.5Hz. Finite element modeling of the rise of a pressurized slug indicates that deformations at the crater rim on the order of a 1mm or less are certainly reasonable. In the case of Santiaguito volcano prior to an eruption we observe a pre eruptive displacement 5-15mm and after the end of an eruption a displacement of up to 1m before the next eruption occurs. This can be interpreted as in

  15. Vailulu'u Seamount, Samoa: Life and Death at the Edge of An Active Submarine Volcano

    NASA Astrophysics Data System (ADS)

    Vailulu'U Research Group, T.

    2005-12-01

    Exploration of Vailulu'u seamount (14°13'S; 169°04'W) by manned submersible, ROV, and surface ship revealed a new, 300m tall volcano that has grown in the summit crater in less than four years. This shows that Vailulu'u's eruption behavior is at this stage not predictable and continued growth could allow Vailulu'u to breach sea level within decades Several types of hydrothermal vents fill Vailulu'u crater with particulates that reduce visibility to less than a few meters in some regions. Hydrothermal solutions mix with seawater that enters the crater from its breaches to produce distinct biological habitats. Low temperature hydrothermal vents can produce Fe-oxide chimneys or up to one meter-thick microbial mats. Higher temperature vents (85°C) produce low salinity acidic fluids containing buoyant droplets of immiscible CO2. Low temperature hydrothermal vents at Nafanua summit (708m depth) support a thriving population of eels (Dysommia rusosa). The areas around the high temperature vents and the moat and remaining crater around the new volcano is almost devoid of any macroscopic life and is littered with fish, and mollusk carcasses that apparently died from exposure to hydrothermal fluid components in deeper crater waters. Acid- tolerant polychaetes adapt to this environment and feed near and on these carcasses. Vailulu'u presents a natural laboratory for the study of how seamounts and their volcanic systems interact with the hydrosphere to produce distinct biological habitats, and how marine life can adapt to these conditions or be trapped in a toxic volcanic system that leads to mass mortality. The Vailulu'u research team: Hubert Staudigel, Samantha Allen, Brad Bailey, Ed Baker, Sandra Brooke, Ryan Delaney, Blake English, Lisa Haucke, Stan Hart, John Helly, Ian Hudson, Matt Jackson, Daniel Jones, Alison Koleszar, Anthony Koppers, Jasper Konter, Laurent Montesi, Adele Pile, Ray Lee, Scott Mcbride, Julie Rumrill, Daniel Staudigel, Brad Tebo, Alexis Templeton

  16. Submarine explosive activity and ocean noise generation at Monowai Volcano, Kermadec Arc: constraints from hydroacoustic T-waves

    NASA Astrophysics Data System (ADS)

    Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony

    2016-04-01

    Submarine volcanic activity is difficult to detect, because eruptions at depth are strongly attenuated by seawater. With increasing depth the ambient water pressure increases and limits the expansion of gas and steam such that volcanic eruptions tend to be less violent and less explosive with depth. Furthermore, the thermal conductivity and heat capacity of water causes rapid cooling of ejected products and hence erupted magma cools much more quickly than during subaerial eruptions. Therefore, reports on submarine volcanism are restricted to those sites where erupted products - like the presence of pumice rafts, gas bubbling on the sea surface, and local seawater colour changes - reach the sea surface. However, eruptions cause sound waves that travel over far distances through the Sound-Fixing-And-Ranging (SOFAR) channel, so called T-waves. Seismic networks in French Polynesia recorded T-waves since the 1980's that originated at Monowai Volcano, Kermadec Arc, and were attributed to episodic growth and collapse events. Repeated swath-mapping campaigns conducted between 1998 and 2011 confirm that Monowai volcano is a highly dynamic volcano. In July of 2007 a network of ocean-bottom-seismometers (OBS) and hydrophones was deployed and recovered at the end of January 2008. The instruments were located just to the east of Monowai between latitude 25°45'S and 27°30'S. The 23 OBS were placed over the fore-arc and on the incoming subducting plate to obtain local seismicity associated with plate bending and coupling of the subduction megathrust. However, we recognized additional non-seismic sleuths in the recordings. Events were best seen in 1 Hz high-pass filtered hydrophone records and were identified as T-waves. The term T-wave is generally used for waves travelling through the SOFAR channel over large distances. In our case, however, they were also detected on station down to ~8000 m, suggesting that waves on the sea-bed station were direct waves caused by explosive

  17. Unusual seismic activity in 2011 and 2013 at the submarine volcano Rocard, Society hot spot (French Polynesia)

    NASA Astrophysics Data System (ADS)

    Talandier, Jacques; Hyvernaud, Olivier; Maury, René C.

    2016-05-01

    We analyze two seismic events that occurred on 27 May 2011 and 29 April 2013 at the Rocard submarine volcano which overlies the Society hot spot. The Polynesian Seismic Network recorded for the first time unusual associated short- and long-period signals, with perfectly monochromatic (0.0589 Hz) Rayleigh wave trains of long period and duration. None of the numerous observations of long-period (10-30 s) signals previously associated with volcanic activity in Japan, Italy, Mexico, Indonesia, Antarctica, and the Hawaiian Islands have the characteristics we observed at Rocard. We propose a tentative model for these unusual and rather enigmatic signals, in which the movement of lava excited the resonance of a shallow open conduit under a high hydrostatic pressure of ~400 bars.

  18. Formation of a zoned magma chamber and its temporal evolution during the historic eruptive activity of Tarumai Volcano, Japan: Petrological implications for a long-term forecast of eruptive activity of an active volcano

    NASA Astrophysics Data System (ADS)

    Nakagawa, Mitsuhiro; Hiraga, Naoto; Furukawa, Ryuta

    2011-08-01

    Tarumai Volcano started a series of historic eruptive activity in AD 1667 after a dormancy of approximately 2000 years. The historic juvenile ejecta are mainly silicic andesite pumice associated with scoria, banded pumice and dome lava (SiO 2 = 55-63%), and are mixing products of two or three end-member magmas. In the initial largest plinian eruptions (AD 1667 period), simple mixing between two end-member magmas, silicic andesite (SA) and basalt, occurred. Large plinian eruptions (AD 1739 period) and the latest intermittent eruptions (AD 1804-AD 1909: latest period) also produced mixed magmas including both the SA, intermediate-SiO 2 andesite (IA), and basalt. Magmatic temperatures of the SA and IA magmas are 900-950 °C and approximately 1000 °C, respectively. The rocks of each period form linear trends in oxide-oxide diagrams, suggesting that mixing of two end-member magmas occurred in each period. Thus, it can be estimated that the IA magma was formed by mixing between the basaltic and SA magmas. These relations suggest that the injection of the basaltic magma into the SA magma occurred before the AD 1667 period, resulting in the formation of a zoned magma chamber. These two magmas were then withdrawn to mingle, during the AD 1667 period. After the period, the zoned chamber was composed of an upper SA magma and a lower mixed IA magma. Chemical compositions of the basaltic magma have been slightly different in each period since AD 1667. In addition, the phenocrystic minerals of the IA magma also have changed as a consequence of re-equilibration with the more mafic IA bulk magma compositions present from AD 1739 to AD 1909. Thus, distinct basaltic magma has repeatedly injected into the zoned chamber before each eruption. Although the scale of eruptions became much smaller after the plinian eruptions of AD 1739, the ratio of IA magma in the latest eruptive materials is much larger than that in AD 1739, suggesting that a larger amount of the lower part (IA magma

  19. The diversity of mud volcanoes in the landscape of Azerbaijan

    NASA Astrophysics Data System (ADS)

    Rashidov, Tofig

    2014-05-01

    As the natural phenomenon the mud volcanism (mud volcanoes) of Azerbaijan are known from the ancient times. The historical records describing them are since V century. More detail study of this natural phenomenon had started in the second half of XIX century. The term "mud volcano" (or "mud hill") had been given by academician H.W. Abich (1863), more exactly defining this natural phenomenon. All the previous definitions did not give such clear and capacious explanation of it. In comparison with magmatic volcanoes, globally the mud ones are restricted in distribution; they mainly locate within the Alpine-Himalayan, Pacific and Central Asian mobile belts, in more than 30 countries (Columbia, Trinidad Island, Italy, Romania, Ukraine, Georgia, Azerbaijan, Turkmenistan, Iran, Pakistan, Indonesia, Burma, Malaysia, etc.). Besides it, the zones of mud volcanoes development are corresponded to zones of marine accretionary prisms' development. For example, the South-Caspian depression, Barbados Island, Cascadia (N.America), Costa-Rica, Panama, Japan trench. Onshore it is Indonesia, Japan, and Trinidad, Taiwan. The mud volcanism with non-accretionary conditions includes the areas of Black Sea, Alboran Sea, the Gulf of Mexico (Louisiana coast), Salton Sea. But new investigations reveal more new mud volcanoes and in places which were not considered earlier as the traditional places of mud volcanoes development (e.g. West Nile Rive delta). Azerbaijan is the classic region of mud volcanoes development. From over 800 world mud volcanoes there are about 400 onshore and within the South-Caspian basin, which includes the territory of East Azerbaijan (the regions of Shemakha-Gobustan and Low-Kura River, Absheron peninsula), adjacent water area of South Caspian (Baku and Absheron archipelagoes) and SW Turkmenistan and represents an area of great downwarping with thick (over 25 km) sedimentary series. Generally, in the modern relief the mud volcanoes represent more or less large uplifts

  20. Volcanoes and the Environment

    NASA Astrophysics Data System (ADS)

    Marti, Edited By Joan; Ernst, Gerald G. J.

    2005-10-01

    Volcanoes and the Environment is a comprehensive and accessible text incorporating contributions from some of the world's authorities in volcanology. This book is an indispensable guide for those interested in how volcanism affects our planet's environment. It spans a wide variety of topics from geology to climatology and ecology; it also considers the economic and social impacts of volcanic activity on humans. Topics covered include how volcanoes shape the environment, their effect on the geological cycle, atmosphere and climate, impacts on health of living on active volcanoes, volcanism and early life, effects of eruptions on plant and animal life, large eruptions and mass extinctions, and the impact of volcanic disasters on the economy. This book is intended for students and researchers interested in environmental change from the fields of earth and environmental science, geography, ecology and social science. It will also interest policy makers and professionals working on natural hazards. An all-inclusive text that goes beyond the geological working of volcanoes to consider their environmental and sociological impacts Each chapter is written by one of the world's leading authorities on the subject Accessible to students and researchers from a wide variety of backgrounds

  1. Geology of Kilauea volcano

    SciTech Connect

    Moore, R.B. . Federal Center); Trusdell, F.A. . Hawaiian Volcano Observatory)

    1993-08-01

    This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower east rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailed geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. 71 refs., 2 figs.

  2. Anatahan Volcano, Mariana Islands

    NASA Technical Reports Server (NTRS)

    2008-01-01

    In the early hours of February 7, ASTER captured this nighttime thermal infrared image of an eruption of Anatahan Volcano in the central Mariana Islands. The summit of the volcano is bright indicating there is a very hot area there. Streaming to the west is an ash plume, visible by the red color indicating the presence of silicate-rich particles. Dark grey areas are clouds that appear colder than the ocean. Anatahan is a stratovolcano that started erupting in May 2003, forming a new crater.

    The image covers an area of 56.3 x 41.8 km, and is located 16 degrees north latitude and 145.6 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  3. The ultimate summit eruption of Puy de Dôme volcano (Chaîne des Puys, French Massif Central) about 10,700 years ago

    NASA Astrophysics Data System (ADS)

    Miallier, Didier; Boivin, Pierre; Deniel, Catherine; Gourgaud, Alain; Lanos, Philippe; Sforna, Marie; Pilleyre, Thierry

    2010-11-01

    The Puy de Dôme volcano is a trachytic lava dome, about 11,000 y old. New pyroclastic layers originating from the volcano itself were discovered covering the summit and the flanks of the volcano. These pyroclastic layers do not fit with the previous interpretation, assuming a non-explosive dome-forming eruption. The tephra display pyroclastic surge features and exhibit fresh trachytic lapilli, basement lithics, allogeneous basaltic lava and clinker fragments requiring an open vent eruption. This ultimate eruption occurred after a period of rest, long enough for vegetation to develop on the volcano, as evidenced by carbonized plant fragments. Radiocarbon dating of some of these fragments gave an age of c.10,700 y also suggesting a significant rest duration.

  4. Warm Brine Lakes in Craters of Active Mud Volcanoes, Menes Caldera off NW Egypt: Evidence for Deep-Rooted Thermogenic Processes

    NASA Astrophysics Data System (ADS)

    Dupré, S.; Mascle, J.; Foucher, J. P.; Woodside, J. M.; Pierre, C.

    2015-12-01

    The Menes caldera is a fault-controlled depression (~8 km in diameter) at ~3,000 m water depth in the western province of the Nile deep-sea fan off NW Egypt, comprising seven mud volcanoes (MVs) of which two are active. Based on multichannel and chirp seismic data, temperature profiles, and high-resolution bathymetric data collected during several oceanographic expeditions, the present study investigates factors controlling mud volcano morphology, the geometry of feeder channels, and the origin of emitted fluids (Dupré et al. 2014). The active Cheops and Chephren mud volcanoes are 1,500 m wide with subcircular craters at their summits, about 250 m in diameter, generally a few tens of metres deep, and filled with methane-rich muddy brines with temperatures reaching 42 °C and 57 °C respectively. Deployments of CTDs and corers with attached temperature sensors tracked these warm temperatures down to almost 0.5 km depth below the brine lake surface at the Cheops mud volcano, in a feeder channel probably only a few tens of metres wide. Thermogenic processes involve the dissolution of Messinian evaporites by warm fluids likely sourced even deeper, i.e. 1.7 and 2.6 km below the seabed at the Cheops and Chephren MVs respectively, and which ascend along listric faults. Seepage activity appears broadly persistent since the initiation of mud volcanism in the Early Pliocene, possibly accompanied by lateral migration of feeder channels.

  5. Space Radar Image of Sakura-Jima Volcano, Japan

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The active volcano Sakura-Jima on the island of Kyushu, Japan is shown in the center of this radar image. The volcano occupies the peninsula in the center of Kagoshima Bay, which was formed by the explosion and collapse of an ancient predecessor of today's volcano. The volcano has been in near continuous eruption since 1955. Its explosions of ash and gas are closely monitored by local authorities due to the proximity of the city of Kagoshima across a narrow strait from the volcano's center, shown below and to the left of the central peninsula in this image. City residents have grown accustomed to clearing ash deposits from sidewalks, cars and buildings following Sakura-jima's eruptions. The volcano is one of 15 identified by scientists as potentially hazardous to local populations, as part of the international 'Decade Volcano' program. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 9, 1994. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth. The image is centered at 31.6 degrees North latitude and 130.6 degrees East longitude. North is toward the upper left. The area shown measures 37.5 kilometers by 46.5 kilometers (23.3 miles by 28.8 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band vertically transmitted, vertically received; green is the average of L-band vertically transmitted, vertically received and C-band vertically transmitted, vertically received; blue is C-band vertically transmitted, vertically received.

  6. Gaseous transport and deposition of gold in magmatic fluid: evidence from the active Kudryavy volcano, Kurile Islands

    NASA Astrophysics Data System (ADS)

    Yudovskaya, Marina A.; Distler, Vadim V.; Chaplygin, Ilya V.; Mokhov, Andrew V.; Trubkin, Nikolai V.; Gorbacheva, Sonya A.

    2006-03-01

    The distribution of gold in high-temperature fumarole gases of the Kudryavy volcano (Kurile Islands) was measured for gas, gas condensate, natural fumarolic sublimates, and precipitates in silica tubes from vents with outlet temperatures ranging from 380 to 870°C. Gold abundance in condensates ranges from 0.3 to 2.4 ppb, which is significantly lower than the abundances of transition metals. Gold contents in zoned precipitates from silica tubes increase gradually with a decrease in temperature to a maximum of 8 ppm in the oxychloride zone at a temperature of approximately 300°C. Total Au content in moderate-temperature sulfide and oxychloride zones is mainly a result of Au inclusions in the abundant Fe-Cu and Zn sulfide minerals as determined by instrumental neutron activation analysis. Most Au occurs as a Cu-Au-Ag triple alloy. Single grains of native gold and binary Au-Ag alloys were also identified among sublimates, but aggregates and crystals of Cu-Au-Ag alloy were found in all fumarolic fields, both in silica tube precipitates and in natural fumarolic crusts. Although the Au triple alloy is homogeneous on the scale of microns and has a composition close to (Cu,Ni,Zn)3(Au,Ag)2, transmission electron microscopy (TEM) shows that these alloy solid solutions consist of monocrystal domains of Au-Ag, Au-Cu, and possibly Cu2O. Gold occurs in oxide assemblages due to the decomposition of its halogenide complexes under high-temperature conditions (650-870°C). In lower temperature zones (<650°C), Au behavior is related to sulfur compounds whose evolution is strongly controlled by redox state. Other minerals that formed from gas transport and precipitation at Kudryavy volcano include garnet, aegirine, diopside, magnetite, anhydrite, molybdenite, multivalent molybdenum oxides (molybdite, tugarinovite, and ilsemannite), powellite, scheelite, wolframite, Na-K chlorides, pyrrhotite, wurtzite, greenockite, pyrite, galena, cubanite, rare native metals (including Fe, Cr, Mo

  7. Temporal change of the mode of eruptive activity and the magma plumbing system of Sakurajima Volcano since 20th century : Implications for forecast future eruptive activity

    NASA Astrophysics Data System (ADS)

    Nakagawa, M.; Matsumoto, A.; Amma-Miyasaka, M.; Togashi, Y.; Iguchi, M.

    2011-12-01

    Sakurajima volcano is a post-caldera volcano of Aira caldera and has repeated large plinian eruptions with dormant periods in AD 1471, AD 1779 and AD 1914. After AD 1914 eruption, medium scale of lava effusion occurred in AD 1946. Since AD 1955, frequent vulcanian eruptions have repeated until now. Thus, mode of eruptive activity of the volcano has changed since 20th century. Based on temporal change of petrological features of these eruptive materials, We discuss the relationship between the mode of eruptive activity and magma system to forecast the future eruptive activity. The rocks of AD 1471 and AD 1779 eruptions are CPX-OPX dacite, in which normally and reversely zoned pyroxene and plagioclase phenocrysts coexist. In addition, compositional distribution of plagioclase phenocrysts is bi-modal. These suggest that these rocks are mixing products between dacitic and andesitic magmas. This is consistent with compositional variations of whole-rock chemistry for these rocks. On the other hand, the rocks of AD 1914 and AD 1946 eruption often contain olivine phenocrysts. Plagioclase and pyroxenes phenocrysts in these rocks show similar features to those of AD 1471 and AD 1779 eruptions, suggesting that these rocks are also mixing products of two end-member magmas, dacitic and andesitic ones. However, olivine phenocrysts are much magnesian compared with pyroxenes phenocrysts, indicating that these olivine phencorysts are derived from another basaltic magma. Thus, the basaltic magma injected into the mixed magma between dacitic and andesitic ones. Mixing among three magmas has been recognized since 20th century. The rocks from frequent eruptions since AD 1955 also contain minor amount of olivine phenocrysts, suggesting the injection of basaltic magma has continued. In 1970's and AD 1987 periods, relatively larger scale of vulcanian eruptions had occurred. The rocks from these periods contain considerable amount of olivine phenocrysts, indicating mixing ratio of the

  8. Active faults on the eastern flank of Etna volcano (Italy) monitored through soil radon measurements

    NASA Astrophysics Data System (ADS)

    Neri, M.; Giammanco, S.; Ferrera, E.; Patanè, G.; Zanon, V.

    2012-04-01

    This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the unstable eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. In particular, the highest anomalies were found at the intersection between WNW-ESE and NW-SE -running faults. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. These maps revealed a progressive deepening of hypocenters from NW to SE, with the exception of a narrow zone in the central part of the area, with a roughly WNW-ESE direction. Also, the highest values of seismic energy were released during events in the southern and northwestern sectors of the area. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquake depth and intensity can give some hints on the source of gas and/or on fault dynamics. Lastly, an important spin-off of this study is the recognition of some areas where radon activity was so high (>50000 Bq/m3) that it may represent a potential hazard to the local population. In fact, radon is the leading cause of lung cancer after cigarette smoke for long exposures and, due to its molecular weight, it accumulates in underground rooms or in low ground, particularly where air circulation is low or absent

  9. Volcano-tectonic implications of 3-D velocity structures derived from joint active and passive source tomography of the island of Hawaii

    USGS Publications Warehouse

    Park, J.; Morgan, J.K.; Zelt, C.A.; Okubo, P.G.

    2009-01-01

    We present a velocity model of the onshore and offshore regions around the southern part of the island of Hawaii, including southern Mauna Kea, southeastern Hualalai, and the active volcanoes of Mauna Loa, and Kilauea, and Loihi seamount. The velocity model was inverted from about 200,000 first-arrival traveltime picks of earthquakes and air gun shots recorded at the Hawaiian Volcano Observatory (HVO). Reconstructed volcanic structures of the island provide us with an improved understanding of the volcano-tectonic evolution of Hawaiian volcanoes and their interactions. The summits and upper rift zones of the active volcanoes are characterized by high-velocity materials, correlated with intrusive magma cumulates. These high-velocity materials often do not extend the full lengths of the rift zones, suggesting that rift zone intrusions may be spatially limited. Seismicity tends to be localized seaward of the most active intrusive bodies. Low-velocity materials beneath parts of the active rift zones of Kilauea and Mauna Loa suggest discontinuous rift zone intrusives, possibly due to the presence of a preexisting volcanic edifice, e.g., along Mauna Loa beneath Kilauea's southwest rift zone, or alternatively, removal of high-velocity materials by large-scale landsliding, e.g., along Mauna Loa's western flank. Both locations also show increased seismicity that may result from edifice interactions or reactivation of buried faults. New high-velocity regions are recognized and suggest the presence of buried, and in some cases, previously unknown rift zones, within the northwest flank of Mauna Loa, and the south flanks of Mauna Loa, Hualalai, and Mauna Kea. Copyright 2009 by the American Geophysical Union.

  10. Volcano seismology

    USGS Publications Warehouse

    Chouet, B.

    2003-01-01

    A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with wide dynamic range, and development of new powerful analysis techniques, rapid progress is being made toward a synthesis of high-quality seismic data to develop a coherent model of eruption mechanics. Examples of recent advances are: (1) high-resolution tomography to image subsurface volcanic structures at scales of a few hundred meters; (2) use of small-aperture seismic antennas to map the spatio-temporal properties of long-period (LP) seismicity; (3) moment tensor inversions of very-long-period (VLP) data to derive the source geometry and mass-transport budget of magmatic fluids; (4) spectral analyses of LP events to determine the acoustic properties of magmatic and associated hydrothermal fluids; and (5) experimental modeling of the source dynamics of volcanic tremor. These promising advances provide new insights into the mechanical properties of volcanic fluids and subvolcanic mass-transport dynamics. As new seismic methods refine our understanding of seismic sources, and geochemical methods better constrain mass balance and magma behavior, we face new challenges in elucidating the physico-chemical processes that cause volcanic unrest and its seismic and gas-discharge manifestations. Much work remains to be done toward a synthesis of seismological, geochemical, and petrological observations into an integrated model of volcanic behavior. Future important goals must include: (1) interpreting the key types of magma movement, degassing and boiling events that produce characteristic seismic phenomena; (2) characterizing multiphase fluids in subvolcanic

  11. Evolution of Popocatépetl volcano's glaciers in Mexico with and without volcanic activity: diagnosis from a minimal mass balance model

    NASA Astrophysics Data System (ADS)

    Ontiveros-Gonzalez, G.; Cortes Ramos, J.; Delgado Granados, H.

    2013-05-01

    This work describes the influence of eruptive activity on the evolution of the glacial cover on Popocatepetl volcano. Here, we try to answer a simple question: what had happened if this glacier had not been affected by the volcanic activity? In order to answer this question we modeled the mass balance evolution of this glacier using meteorological data and a minimal mass balance model developed for glaciers elsewhere. For this model we assumed no volcanic activity. These results were compared with measurements available for the actual situation at Popocatépetl Volcano. It was possible to separate the influence of the volcanic activity on the evolution of this glacier system considering two scenarios: one was modeled with a simulation of the mass balance where volcanic activity does not affect, and a second scenario is based on the documented studies developed around the glacial disappearance of the glaciers.

  12. A new method to monitor water vapor cycles in active volcanoes

    NASA Astrophysics Data System (ADS)

    Girona, T.; Costa Rodriguez, F.; Taisne, B.

    2014-12-01

    Simultaneous monitoring of different gas species of volcanic plumes is crucial to understand the mechanisms involved in persistent degassing, and to anticipate volcanic unrest episodes and magma ascent towards the surface. Progress in gas remote-sensing techniques during the last decades has led to the development of ultraviolet absorption spectrometers and UV cameras, which enable to monitor SO2 emission cycles in real time, at very high-frequency (~ 1Hz), and from several kilometers away from the volcanic plume. However, monitoring of the more abundant gases, i.e., H2O and CO2, is limited to volcanoes where infrared spectrometers and infrared lamps can be installed at both sides of the crater rims. In this study, we present a new and simple methodology to register H2O emission cycles from long distances (several kilometers), which is based on the light scattered by the micrometric water droplets of condensed plumes. The method only requires a commercial digital camera and a laptop for image processing, since, as we demonstrate, there is a linear correlation between the digital brightness of the plume and its volcanogenic water content. We have validated the method experimentally by generating controlled condensed plumes with an ultrasonic humidifier, and applied it to the plume of Erebus volcano using a 30 minutes-long movie [1]. The wavelet transforms of the plume brightness and SO2 time series (measured with DOAS [1]) show two common periodic components in the bands ~100­-250 s and ~500-­650 s. However, there is a third periodic component in the band ~300-­450 s in the SO2 time series that is absent in the brightness time series. We propose that the common periodic components are induced by magmatic foams collapsing intermittently beneath shallow geometrical barriers composed by bubbles with high content of both H2O and SO2, whereas the third periodic component could be induced by foams collapsing beneath a deeper geometrical barrier composed by bubbles with

  13. Analysis of dynamics of vulcanian activity of Ubinas volcano, using multicomponent seismic antennas

    NASA Astrophysics Data System (ADS)

    Inza, L. A.; Métaxian, J. P.; Mars, J. I.; Bean, C. J.; O'Brien, G. S.; Macedo, O.; Zandomeneghi, D.

    2014-01-01

    A series of 16 vulcanian explosions occurred at Ubinas volcano between May 24 and June 14, 2009. The intervals between explosions were from 2.1 h to more than 6 days (mean interval, 33 h). Considering only the first nine explosions, the average time interval was 7.8 h. Most of the explosions occurred after a short time interval (< 8 h) and had low energy, which suggests that the refilling time was not sufficient for large accumulation of gas. A tremor episode followed 75% of the explosions, which coincided with pulses of ash emission. The durations of the tremors following the explosions were longer for the two highest energy explosions. To better understand the physical processes associated with these eruptive events, we localized the sources of explosions using two seismic antennas that were composed of three-component 10 and 12 sensors. We used the high-resolution MUSIC-3C algorithm to estimate the slowness vector for the first waves that composed the explosion signals recorded by the two antennas assuming propagation in a homogeneous medium. The initial part of the explosions was dominated by two frequencies, at 1.1 Hz and 1.5 Hz, for which we identified two separated sources located at 4810 m and 3890 m +/- 390 altitude, respectively. The position of these two sources was the same for the full 16 explosions. This implies the reproduction of similar mechanisms in the conduit. Based on the eruptive mechanisms proposed for other volcanoes of the same type, we interpret the position of these two sources as the limits of the conduit portion that was involved in the fragmentation process. Seismic data and ground deformation recorded simultaneously less than 2 km from the crater showed a decompression movement 2 s prior to each explosion. This movement can be interpreted as gas leakage at the level of the cap before its destruction. The pressure drop generated in the conduit could be the cause of the fragmentation process that propagated deeper. Based on these

  14. Gravity changes and deformation at Kīlauea Volcano, Hawaii, associated with summit eruptive activity, 2009-2012

    USGS Publications Warehouse

    Bagnardi, Marco; Poland, Michael P.; Carbone, Daniele; Baker, Scott; Battaglia, Maurizio; Amelung, Falk

    2014-01-01

    Analysis of microgravity and surface displacement data collected at the summit of Kīlauea Volcano, Hawaii (USA), between December 2009 and November 2012 suggests a net mass accumulation at ~1.5 km depth beneath the northeast margin of Halema‘uma‘u Crater, within Kīlauea Caldera. Although residual gravity increases and decreases are accompanied by periods of uplift and subsidence of the surface, respectively, the volume change inferred from the modeling of interferometric synthetic aperture radar deformation data can account for only a small portion (as low as 8%) of the mass addition responsible for the gravity increase. We propose that since the opening of a new eruptive vent at the summit of Kīlauea in 2008, magma rising to the surface of the lava lake outgasses, becomes denser, and sinks to deeper levels, replacing less dense gas-rich magma stored in the Halema‘uma‘u magma reservoir. In fact, a relatively small density increase (<200 kg m−3) of a portion of the reservoir can produce the positive residual gravity change measured during the period with the largest mass increase, between March 2011 and November 2012. Other mechanisms may also play a role in the gravity increase without producing significant uplift of the surface, including compressibility of magma, formation of olivine cumulates, and filling of void space by magma. The rate of gravity increase, higher than during previous decades, varies through time and seems to be directly correlated with the volcanic activity occurring at both the summit and the east rift zone of the volcano.

  15. Gravity changes and deformation at Kīlauea Volcano, Hawaii, associated with summit eruptive activity, 2009-2012

    NASA Astrophysics Data System (ADS)

    Bagnardi, Marco; Poland, Michael P.; Carbone, Daniele; Baker, Scott; Battaglia, Maurizio; Amelung, Falk

    2014-09-01

    Analysis of microgravity and surface displacement data collected at the summit of Kīlauea Volcano, Hawaii (USA), between December 2009 and November 2012 suggests a net mass accumulation at ~1.5 km depth beneath the northeast margin of Halema`uma`u Crater, within Kīlauea Caldera. Although residual gravity increases and decreases are accompanied by periods of uplift and subsidence of the surface, respectively, the volume change inferred from the modeling of interferometric synthetic aperture radar deformation data can account for only a small portion (as low as 8%) of the mass addition responsible for the gravity increase. We propose that since the opening of a new eruptive vent at the summit of Kīlauea in 2008, magma rising to the surface of the lava lake outgasses, becomes denser, and sinks to deeper levels, replacing less dense gas-rich magma stored in the Halema`uma`u magma reservoir. In fact, a relatively small density increase (<200 kg m-3) of a portion of the reservoir can produce the positive residual gravity change measured during the period with the largest mass increase, between March 2011 and November 2012. Other mechanisms may also play a role in the gravity increase without producing significant uplift of the surface, including compressibility of magma, formation of olivine cumulates, and filling of void space by magma. The rate of gravity increase, higher than during previous decades, varies through time and seems to be directly correlated with the volcanic activity occurring at both the summit and the east rift zone of the volcano.

  16. A warning model based on temporal changes of coda Q for volcanic activity at Nevado Del Ruiz Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Londoño, John M.; Sudo, Yasuaki

    2002-07-01

    The coda Q has been calculated for Nevado del Ruiz Volcano, Colombia (NRV) from 1985 to 1999 by using a single scattering model. During this period, the inverse of Q (Q-1 proportional to attenuation) exhibited a long-term decrease with time, as well as shorter-term variations related to the volcanic activity. Q-1 increased prior to volcanic crises and decreased afterward. Based on these observations, a seismic warning criterion has been developed. The parameters (frequency band, size of moving average window, and threshold levels) necessary to evidence clear and significant short-term changes in Q-1 have been investigated and appropriated values are proposed. We suggest a phenomenological model with three stages for the short-term temporal changes in Q-1 at NRV. Firstly, Q-1 increases before a volcanic crises because of accumulation of gas and/or liquid, which decreases the aspect ratio of fluid pockets and increases the fractional volume of fluid in the rocks and the pore aspect ratio. Secondly, Q-1 starts to decrease during the crises by the discharging of fluids such as gas, water, etc. from the volcano. Finally, Q-1 becomes more stable after the crisis at a lower value because of the degassing and/or increasing of rigidity of the medium because of the long-term crystallization and cooling processes. Q-1 seems to be a promising monitoring tool at NRV. It is possible that the observed temporal changes of Q-1, combined with other parameters, may help to predict with greater accuracy a volcanic crisis at NRV.

  17. High-resolution seismic tomography of compressional wave velocity structure at Newberry Volcano, Oregon Cascade Range

    SciTech Connect

    Achauer, U.; Evans, J.R.; Stauber, D.A.

    1988-09-10

    Compressional wave velocity structure is determined for the upper crust beneath Newberry Volcano, central Oregon, using a high-resolution active-source seismic-tomography method. Newberry Volcano is a bimodal shield volcano east of the axis of the Cascade Range. It is associated both with the Cascade Range and with northwest migrating silicic volcanism in southeast Oregon. High-frequency (approx.7 Hz) crustal phases, nominally Pg and a midcrustal reflected phase, travel upward through a target volume beneath Newberry Volcano to a dense array of 120 seismographs. This arrangement is limited by station spacing to 1- to 2-km resolution in the upper 5 to 6 km of the crust beneath the volcano's summit caldera. The experiment tests the hypothesis that Cascade Range volcanoes are underlain only by small magma chambers. A small low-velocity anomaly delineated abosut 3 km below the summit caldera supports this hypothesis for Newberry Volcano and is interpreted as a possible magma chamber of a few to a few tens of km/sup 3/ in volume. A ring-shaped high-velocity anomaly nearer the surface coincides with the inner mapped ring fractures of the caldera. It also coincides with a circular gravity high, and we interpret it as largely subsolidus silicic cone sheets. The presence of this anomaly and of silicic vents along the ring fractures suggests that the fractures are a likely eruption path between the small magma chamber and the surface.

  18. The central power source in active galaxies

    NASA Astrophysics Data System (ADS)

    Ptak, Roger; Stoner, Ronald

    Potential sources for the central power in AGN are examined. The continuum, emission line profiles, and time variability and broad emission line region for AGN are analyzed. The supermassive black hole hypothesis, the supermassive magnetized core model of Kundt (1978), and the model of Stoner and Ptak (1984) in which the supermassive stars maintain a kind of long-term quasi-stability, but accretion is balanced by mass loss and spherical bursts rather than in jets are considered. It is argued that the hypothesis that the supermassive blackholes are the central engines for AGN is based on theoretical principles; however, AGN emission line profiles and variability suggest a spherical geometry for the observed components of these engines. Also the supermassive black hole models do not account for all the AGN observations.

  19. The Volcano Adventure Guide

    NASA Astrophysics Data System (ADS)

    Lopes, Rosaly

    2005-02-01

    This guide contains vital information for anyone wishing to visit, explore, and photograph active volcanoes safely and enjoyably. Following an introduction that discusses eruption styles of different types of volcanoes and how to prepare for an exploratory trip that avoids volcanic dangers, the book presents guidelines to visiting 42 different volcanoes around the world. It is filled with practical information that includes tour itineraries, maps, transportation details, and warnings of possible non-volcanic dangers. Three appendices direct the reader to a wealth of further volcano resources in a volume that will fascinate amateur enthusiasts and professional volcanologists alike. Rosaly Lopes is a planetary geology and volcanology specialist at the NASA Jet Propulsion Laboratory in California. In addition to her curatorial and research work, she has lectured extensively in England and Brazil and written numerous popular science articles. She received a Latinas in Science Award from the Comision Feminil Mexicana Nacional in 1991 and since 1992, has been a co-organizer of the United Nations/European Space Agency/The Planetary Society yearly conferences on Basic Science for the Benefit of Developing Countries.

  20. Water content and hydrogen behaviour during metasomatism in the uppermost mantle beneath Ray Pic volcano (Massif Central, France)

    NASA Astrophysics Data System (ADS)

    Denis, Carole M. M.; Alard, Olivier; Demouchy, Sylvie

    2015-11-01

    To understand the deep cycle of water, upper mantle water content and distribution between nominally anhydrous minerals (NAMs) and hydrous minerals (e.g., amphibole) must be constrained. We need then to understand H behaviour during mantle melting and metasomatism. Major, minor and trace element compositions including water contents were obtained on ten xenoliths of spinel-bearing peridotites from the Ray Pic locality, in the Southern part of the Massif Central (France). The sample suite investigated here is composed of rather fertile lherzolites (89.4 ≤ Fo ≤ 90.8%; 11.3 ≤ cr# in spinel ≤ 21.1%; 0.942 ≤ [Yb]cpx ≤ 1.90 ppm; cpx: clinopyroxene), which can be best explained by batch melting, with degree of melting between 3 and 10%. These xenoliths contain up to 8% modal amphibole. Three groups are defined as a function of the amphibole modal abundance (above or below 1%) and equilibrium temperature (above or below 1000 °C). Results show no clear positive correlation between modal metasomatism (amphibole) and incompatible element enrichment in cpx. Trace element compositions in cpx show strong enrichments of the most incompatible elements (e.g., (La/Sm)PM as high as 15.7; PM: normalised to primitive mantle values), but strong negative anomalies of the high field strength elements (e.g., (Th/Nb)PM as high as ~ 680). Such trace element fractionations are usually ascribed to the so-called carbonatitic metasomatism involving the percolation of small volume melts which are enriched in volatiles. The hydrogen concentrations in cpx range from 203 to 330 ppm wt. H2O, in orthopyroxene from 66 to 160 ppm wt. H2O and in olivine from 2 to 6 ppm wt. H2O. These values are within the common concentration range of other spinel-bearing peridotites. Amphiboles contain 1.9 ± 0.5 wt.% of H2O. The effect of metasomatism on water abundances in NAMs is not straightforward. Hydrous metasomatism (i.e., leading to the crystallisation of OH-bearing amphibole) has no effect on the

  1. Real-time measurements of Hg0 and H2S at La Solfatara Crater (Campi Flegrei, Southern Italy) and Mt. Amiata volcano (Siena, Central Italy): a new geochemical approach to estimate the distribution of air contaminants

    NASA Astrophysics Data System (ADS)

    Cabassi, J.; Calabrese, S.; Tassi, F.; Venturi, S.; Capecchiacci, F.; Di Lonardo, C.; D'Alessandro, W.; Vaselli, O.

    2014-12-01

    The emission of Hg and H2S from natural and anthropogenic sources may have a great environmental impact in urban areas as well as in the surroundings of active and passive degassing volcanoes. Mercury is present in the atmosphere mainly in its elemental form (Hg0~98 %), which has a relatively high volatility, low solubility and chemical inertness. Hydrogen sulfide, one of the most abundant gas species in volcanic fluids, is highly poisoning and corrosive. In this study, an innovative real-time method for the measurements of Hg0 and H2S concentrations in air was carried out at La Solfatara Crater, a hydrothermally altered tuff-cone nested in the town of Pozzuoli (Southern Italy), and at Mt. Amiata volcano (Central Italy), where a world-class Hg mining district abandoned in the seventies and a presently-exploited geothermal field for the production of electrical energy occur. The main aims were (i) to test this new methodological approach and (ii) to investigate Hg0 and H2S concentrations and the chemical-physical parameters regulating their spatial distribution in polluted areas. A portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M) was used in combination with a pulsed fluorescence gas analyzer (Thermo Scientific Model 450i) to measure Hg0 and H2S, respectively. The instruments were synchronized and set at high-frequency acquisition (10 sec and 1 min, respectively). Measurements were carried out along pathways (up to 12 km long) at an average speed of <10 km/h and coupled with GPS data and meteorological parameters. In selected sites, passive samplers were positioned to determine the time-integrated Hg0 and H2S concentrations to be compared with the real-time measurements. The results indicate that this approach is highly efficient and effective in providing reliable and reproducible Hg0 and H2S concentrations and can be used to identify and characterize gas emitters in different environments.

  2. Volcanoes triggered by dynamic and static stress changes in Chile: Observations, stress field changes and physical modelling

    NASA Astrophysics Data System (ADS)

    Gaete, Ayleen; Walter, Thomas

    2015-04-01

    Evidence is increasing that subduction zone earthquakes may influence the volcanic activity along a volcanic arc. The processes of triggering, however, are not clear. In a commonly discussed concept, changes of the crustal stress field may affect intrusive bodies under volcano, open magma pathways and faults, and decompress a magma-fluid system. Other concepts focus on the dynamic passage of seismic waves, inducing bubble growth and ascent as well as fluid migration. Volcanoes in the south and central Andes have a century long documented history of earthquake - eruption interactions. Numerous subduction earthquakes were followed by more and unexpected volcano eruptions, which is why we here concentrate our research on this particular area. The most recent major subduction earthquake occurred on April 1st, 2014, close to the coast of northern Chile. During this event we had volcano monitoring stations located at several active volcanoes and fumarole sites, as well as at on of the largest geyser fields of the world, all located within 500 km distance to the earthquake epicenter. Here we present preliminary results describing if and how those monitored volcano sites showed activity level changes, which is an opportunity to study the influence of earthquakes over active and dormant volcanoes. After analysis of the date we computed the static strain and stress field in the overriding plate and at the sites of the volcanoes. In addition we design physical models that allow to study not only the effects of static stress changes and dilatation on fluid paths, but also the effect of dynamic processes. To this aim we simulate real seismic waveforms on a shaking table hosting an analogue volcano, and discuss under which situations magma paths and ascent rates are augmented and hindered by the subduction earthquake. Results are transferrable to other subduction related volcano-earthquake interactions and may allow better understanding of the processes of static and dynamic

  3. Developments in analysis of basaltic ash applied to recent activity at Stromboli and Etna volcanoes

    NASA Astrophysics Data System (ADS)

    Lautze, Nicole; Taddeucci, Jacopo; Andronico, Daniele; Tornetta, Lauretta; Cannata, Chiara; Cristaldi, Antonio

    2010-05-01

    Volcanic ash is widely distributed and therefore generally safe to collect in real-time, however, there is a paucity of published studies that characterize the textural properties of ash (relative to larger clasts), probably because its small size makes ash inherently difficult to analyze. Recent advances in analytical techniques enable automated, relatively quick, quantitative classification of the morphoscopy and surface chemistry of a hundreds of ash particles using a Field Emission SEM. We present results of such analysis on eight samples of ash collected at different locations from a weak ash-producing event at Etna on 24 November 2006, and seven samples of ash collected during the 2007 eruptive crisis of Stromboli. The latter includes ash from lava-sea water interaction, the paroxysmal explosion on 15 March, and Strombolian explosions at the summit craters. The morphoscopy data can be compared to grain size data collected by conventional techniques, while the surface chemistry data can be considered a proxy for component analysis, as it reflects the degree of crystallinity and alteration of the particles. Our data show that insight into the particle source and eruptive dynamics of both volcanoes can be obtained from this detailed analysis of the ash. In particular, the different sources of ash at Stromboli have distinctive alteration signatures, while the Etna samples show subtle differences that can be related to relatively small-scale plume zonations.

  4. Mantle to surface gas triggers of magmatic activity at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Oppenheimer, C.; Moretti, R.; Kyle, P.

    2009-04-01

    Intraplate volcanoes are associated with extensional tectonics, mantle upwelling and high heat flow. Erupted magmas have an alkaline nature and are rich in volatiles, especially CO2, that are inherited from fluid-rich magmatic sources in the mantle. Localized alkaline centers emit gas fluxes that exceed what can be sustained by the rates of magma erupted. At Mount Erebus this dichotomy is evidenced by open-path Fourier transform infrared (FTIR) spectroscopy of gases released from the lava lake. Different gas signatures are associated with explosive and non-explosive gas emissions, representative of volatile contents and redox conditions that identify the overlap between shallow and deep degassing sources. We show that this multiple signature of magma degassing provides a unique probe for magma differentiation and transfer of CO2-rich oxidized fluids from lithospheric roots up to the surface, and show how these processes operate in time and space. Magma deeper than 4 km equilibrates under vapour buffered conditions, whereas shallower magmas allow deep, CO2-rich fluids to accumulate and prior to release either via open-system degassing conditions and reduced oxidation states, or as volatile-enriched, phonolitic blobs that preserve the deep oxidized signature, and ascend as a closed-system to explode at the surface during Strombolian phases.

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

    NASA Astrophysics Data System (ADS)

    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

  6. Evolution of large shield volcanoes on Venus

    NASA Technical Reports Server (NTRS)

    Herrick, Robert R.; Dufek, Josef; McGovern, Patrick J.

    2005-01-01

    We studied the geologic history, topographic expression, and gravity signature of 29 large Venusian shield volcanoes with similar morphologies in Magellan synthetic aperture radar imagery. While they appear similar in imagery, 16 have a domical topographic expression and 13 have a central depression. Typical dimensions for the central depression are 150 km wide and 500 m deep. The central depressions are probably not calderas resulting from collapse of a shallow magma chamber but instead are the result of a corona-like sagging of a previously domical volcano. The depressions all have some later volcanic filling. All but one of the central depression volcanoes have been post-dated by geologic features unrelated to the volcano, while most of the domical volcanoes are at the top of the stratigraphic column. Analysis of the gravity signatures in the spatial and spectral domains shows a strong correlation between the absence of post-dating features and the presence of dynamic support by an underlying plume. We infer that the formation of the central depressions occurred as a result of cessation of dynamic support. However, there are some domical volcanoes whose geologic histories and gravity signatures also indicate that they are extinct, so sagging of the central region apparently does not always occur when dynamic support is removed. We suggest that the thickness of the elastic lithosphere may be a factor in determining whether a central depression forms when dynamic support is removed, but the gravity data are of insufficient resolution to test this hypothesis with admittance methods.

  7. Thematic mapper studies of Andean volcanoes

    NASA Technical Reports Server (NTRS)

    Francis, P. W.

    1986-01-01

    The primary objective was to identify all the active volcanoes in the Andean region of Bolivia. Morphological features of the Tata Sabaya volcano, Bolivia, were studied with the thematic mapper. Details include marginal levees on lava and pyroclastic flows, and summit crater structure. Valley glacier moraine deposits, not easily identified on the multispectral band scanner, were also unambiguous, and provide useful marker horizons on large volcanic edifices which were built up in preglacial times but which were active subsequently. With such high resolution imagery, it is not only possible to identify potentially active volcanoes, but also to use standard photogeological interpretation to outline the history of individual volcanoes.

  8. Volcano plumbing system geometry: The result of multi-parametric effects

    NASA Astrophysics Data System (ADS)

    Tibaldi, Alessandro

    2014-05-01

    Magma is transported from magma chambers towards the surface through networks of planar structures (intrusive sheets) spanning from vertical dikes to inclined sheets and horizontal sills. This study presents an overview of intrusive sheets at several volcanoes located in different settings in order to contribute to assess the factors controlling the geometry of magma plumbing systems. Data have been mainly acquired in the field and secondarily through a collection and analysis of geophysical publications; data include local lithology and tectonics of the substratum surrounding the volcano with special reference to local fault kinematics and related stress tensor, regional tectonics (general kinematics and far-field stress tensors), crustal thickness, geology and shape of the volcano, topographic setting, and characteristics of the plumbing system. Data from active volcanoes and eroded extinct volcanoes are discussed; the shallow plumbing system of active volcanoes has been reconstructed by combining available geophysical data with field information derived from outcropping sheets, morphometric analyses of pyroclastic cones, and the orientation and location of eruptive fissures. The study of eroded volcanoes enabled to assess the plumbing system geometry at lower levels in the core of the edifice or under the volcano-substratum interface. Key sites are presented in extensional, transcurrent and contractional tectonic settings, and different geodynamic areas have been investigated in North and South-America, Iceland, Southern Tyrrhenian Sea and Africa. The types of sheet arrangements that are illustrated include swarms of parallel dikes, diverging rift patterns, centrally-inclined sheets, radial dikes, bi-modal dike strikes, circum-lateral collapse sheets, and mixed members. This review shows that intrusive sheet emplacement at a volcano depends upon the combination of several local and regional factors, some of which are difficult to be constrained. While much

  9. Interaction between ultrapotassic magmas and carbonate rocks: Evidence from geochemical and isotopic (Sr, Nd, O) compositions of granular lithic clasts from the Alban Hills Volcano, Central Italy

    NASA Astrophysics Data System (ADS)

    Peccerillo, Angelo; Federico, Marcella; Barbieri, Mario; Brilli, Mauro; Wu, Tsai-Wan

    2010-05-01

    Magma-carbonate rock interaction is investigated through a geochemical and Sr-Nd-O isotope study of granular lithic clasts ( ejecta) from the Alban Hills ultrapotassic volcano, Central Italy. Some samples (Group-1) basically represent intrusive equivalents of Alban Hills magmas. A few samples (Group-2) are ultramafic, have high MgO (˜30 to 40 wt%) and δ 18O‰, and originated by accumulation of mafic phases that crystallised from ultrapotassic melts during assimilation of dolomitic rocks. Group-3 ejecta consist of dominant K-feldspar, and show major element compositions similar to phonolites, which, however, are absent among the Alban Hills volcanics. Finally, another group (Group-4) contains corroded K-feldspars, surrounded by a microgranular to porphyritic matrix, made of igneous minerals (K-feldspar, foids, clinopyroxene, phlogopite) plus wollastonite, garnet, and some cuspidine. Group-4 ejecta are depleted in SiO 2 and enriched in CaO with respect to Group-3. The analysed ejecta have similar 143Nd/ 144Nd (0.51204-0.51217) as the Alban Hills lavas, whereas 87Sr/ 86Sr (0.70900-0.71067) is similar to lower. Whole rocks δ 18O‰ ranges from +7.0 to +13.2, reaching maximum values in ultramafic samples. A positive correlation with CaO is observed in single rock groups. Large Ion Lithophile Element (LILE) abundances and REE fractionation are generally high, and extreme values of Th, U and LREE are found in some Group-3 and Group-4 rocks. Mineralogical, petrological and geochemical data reveal extensive interaction between magma and carbonate wall rocks, involving both dolostones and limestones. These processes had dramatic effects on magma compositions, especially on phonolites, which were transformed to foidites. Evidence of such a process is found in Group-4 samples, in which K-feldspar is observed to react with a matrix that represents strongly undersaturated melts formed by interaction between silicate magma and carbonates. Trace element data also testify to a

  10. Shiveluch and Klyuchevskaya Volcanoes

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A distance of about 80 kilometers (50 miles) separates Shiveluch and Klyuchevskaya Volcanoes on Russia's Kamchatka Peninsula. Despite this distance, however, the two acted in unison on April 26, 2007, when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite caught them both erupting simultaneously. ASTER 'sees' a slightly different portion of the light spectrum than human eyes. Besides a portion of visible light, ASTER detects thermal energy, meaning it can detect volcanic activity invisible to human eyes. Inset in each image above is a thermal infrared picture of the volcano's summit. In these insets, dark red shows where temperatures are coolest, and yellowish-white shows where temperatures are hottest, heated by molten lava. Both insets show activity at the crater. In the case of Klyuchevskaya, some activity at the crater is also visible in the larger image. In the larger images, the landscapes around the volcanoes appear in varying shades of blue-gray. Dark areas on the snow surface are likely stains left over from previous eruptions of volcanic ash. Overhead, clouds dot the sky, casting their shadows on the snow, especially southeast of Shiveluch and northeast of Klyuchevskaya. To the northwest of Klyuchevskaya is a large bank of clouds, appearing as a brighter white than the snow surface. Shiveluch (sometimes spelled Sheveluch) and Klyuchevskaya (sometimes spelled Klyuchevskoy or Kliuchevskoi) are both stratovolcanoes composed of alternating layers of hardened lava, solidified ash, and rocks from earlier eruptions. Both volcanoes rank among Kamchatka's most active. Because Kamchatka is part of the Pacific 'Ring of Fire,' the peninsula experiences regular seismic activity as the Pacific Plate slides below other tectonic plates in the Earth's crust. Large-scale plate tectonic activity causing simultaneous volcanic eruptions in Kamchatka is not uncommon.

  11. January 2002 volcano-tectonic eruption of Nyiragongo volcano, Democratic Republic of Congo

    NASA Astrophysics Data System (ADS)

    Tedesco, D.; Vaselli, O.; Papale, P.; Carn, S. A.; Voltaggio, M.; Sawyer, G. M.; Durieux, J.; Kasereka, M.; Tassi, F.

    2007-09-01

    In January 2002, Nyiragongo volcano erupted 14-34 × 106 m3 of lava from fractures on its southern flanks. The nearby city of Goma was inundated by two lava flows, which caused substantial socioeconomic disruption and forced the mass exodus of the population, leaving nearly 120,000 people homeless. Field observations showed marked differences between the lava erupted from the northern portion of the fracture system and that later erupted from the southern part. These observations are confirmed by new 238U and 232Th series radioactive disequilibria data, which show the presence of three different phases during the eruption. The lavas first erupted (T1) were probably supplied by a residual magma batch from the lava lake activity during 1994-1995. These lavas were followed by a fresh batch erupted from fissure vents as well as later (May-June 2002) from the central crater (T2). Both lava batches reached the surface via the volcano's central plumbing system, even though a separate flank reservoir may also have been involved in addition to the main reservoir. The final phase (T3) is related to an independent magmatic reservoir located much closer (or even beneath) the city of Goma. Data from the January 2002 eruption, and for similar activity in January 1977, suggest that the eruptive style of the volcano is likely to change in the future, trending toward more common occurrence of flank eruptions. If so, this would pose a significant escalation of volcanic hazards facing Goma and environs, thus requiring the implementation of different volcano-monitoring strategies to better anticipate where and when future eruptions might take place.

  12. Paleoseismology of latest Pleistocene and Holocene fault activity in central Oregon

    SciTech Connect

    Pezzopane, S.K.; Weldon, R.J. II . Dept. of Geological Sciences)

    1993-04-01

    Latest Pleistocene and Holocene fault activity in Oregon concentrates along four zones that splay northward from seismically active faults along the Central Nevada and Eastern California seismic zones. The Central Oregon fault zone is one of these zones, which splays northward from dextral faults of the Walker Lane, stretching across the flanks of several ranges in south-central Oregon along a N20[degree]W trend, and ultimately merges with the Cascade volcanic arc near Newberry volcano. Aerial-photo interpretations and field investigations reveal fault scarps with, on average about 4 m, but in places as much as [approximately]10 m of vertical expression across latest Pleistocene pluvial lake deposits and geomorphic surfaces. Trenches across three different faults in the Central Oregon zone reveal evidence for multiple episodes of faulting in the form of fault-related colluvial deposits and deformed horizons which have been cut by younger fault movements. Trench exposures reveal faults with relatively steep dips and anastomosing traces, which are interpreted locally as evidence for a small oblique-slip component. Vertical offsets measured in the trenches are [approximately]2 m or more for each event. Radiocarbon analyses and preliminary tephra correlations indicate that the exposed deposits are [approximately]30,000 yr in age and younger, and record the decline of latest Pleistocene pluvial lakes. Commonly, reworked or deformed lacustrine deposits and interlayered and faulted colluvial deposits mark the second and third events back, which probably occurred in the Latest Pleistocene, at a time during low to moderate lake levels. If offsets of the past 18,000 yr are representative of the long-term average, then faults along this zone have slip rates of from 0.2 mm/yr to 0.6 mm/yr and recurrence intervals that range from [approximately]4,000 yr to 11,000 yr.

  13. Palynoflora from Deccan volcano-sedimentary sequence (Cretaceous-Palaeogene transition) of central India: implications for spatio-temporal correlation.

    PubMed

    Samant, B; Mohabey, D M

    2009-11-01

    The sedimentary beds associated with Deccan Continental Flood Basalt (DCFB) sequences exposed in the volcanic subprovinces of Jabalpur-Mandla-Chhindwara (JMC) regions of Madhya Pradesh and Nand-Dongargaon (N-D) basin and the adjoining areas to the west in Yeotmal-Nanded in Maharashtra were studied for their palynofloral analysis. The sediments were characterized palynologically and changes in the palynoflora are observed at different stratigraphic levels in a number of sections including several new intertrappean localities recorded in recent years. For the purpose of effective correlation of different subprovinces, palynofloras of some of the previously studied intertrappeans are also reviewed. Our studies suggest that before the start of the Deccan volcanic activity, the palynoflora found in the Lameta sediments, was dominated by gymnosperms-angiosperm association. The plant canopy consisted mainly of gymnosperms (Conifers and Podocarpaceae) whereas, the understory members were mostly of palms and herbs (Poaceae and Asteraceae). The eruption of Deccan volcanic flows severely affected the existing floral association and proved fatal for the well established plant community. The immediately overlying sediments associated with the earliest volcanic flows are dominated by pteridophytes and angiosperm taxa (Azolla cretacea, Aquilapollenites bengalensis, Ariadnaesporites sp., Gabonisporis vigourouxii and Tripo