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Sample records for active geyser-like eruptions

  1. Triton's geyser-like plumes - Discovery and basic characterization

    NASA Technical Reports Server (NTRS)

    Soderblom, L. A.; Becker, T. L.; Kieffer, S. W.; Brown, R. H.; Hansen, C. J.; Johnson, T. V.

    1990-01-01

    One model for the mechanism driving the plumes of the four active geyser-like eruptions observed by Voyager 2 on Triton is a heating up of nitrogen ice in a subsurface greenhouse environment, where nitrogen gas pressurized by solar heating explosively vents to the surface carrying clouds of ice and dark particles into the atmosphere. A temperature increase of less than 4 K above the ambient surface value of 38 + or - 3 K suffices to drive the plumes to 8-km altitude. Each eruption may last a year or more, over the course of which 0.1 cu km of ice is sublimed.

  2. Triton's geyser-like plumes: Discovery and basic characterization

    USGS Publications Warehouse

    Soderblom, L.A.; Kieffer, S.W.; Becker, T.L.; Brown, R.H.; Cook, A.F., II; Hansen, C.J.; Johnson, T.V.; Kirk, R.L.; Shoemaker, E.M.

    1990-01-01

    At least four active geyser-like eruptions were discovered in Voyager 2 images of Triton, Neptune's large satellite. The two best documented eruptions occur as columns of dark material rising to an altitude of about 8 kilometers where dark clouds of material are left suspended to drift downwind over 100 kilometers. The radii of the rising columns appear to be in the range of several tens of meters to a kilometer. One model for the mechanism to drive the plumes involves heating of nitrogen ice in a sub-surface greenhouse environment; nitrogen gas pressurized by the solar heating explosively vents to the surface carrying clouds of ice and dark particles into the atmosphere. A temperature increase of less than 4 kelvins above the ambient surface value of 38 ?? 3 kelvins is more than adequate to drive the plumes to an 8-kilometer altitude. The mass flux in the trailing clouds is estimated to consist of up to 10 kilograms of fine dark particles per second or twice as much nitrogen ice and perhaps several hundred or more kilograms of nitrogen gas per second. Each eruption may last a year or more, during which on the order of a tenth of a cubic kilometer of ice is sublimed.

  3. Triton's Geyser-Like Plumes: Discovery and Basic Characterization.

    PubMed

    Soderblom, L A; Kieffer, S W; Becker, T L; Brown, R H; Cook, A F; Hansen, C J; Johnson, T V; Kirk, R L; Shoemaker, E M

    1990-10-19

    At least four active geyser-like eruptions were discovered in Voyager 2 images of Triton, Neptune's large satellite. The two best documented eruptions occur as columns of dark material rising to an altitude of about 8 kilometers where dark clouds of material are left suspended to drift downwind over 100 kilometers. The radii of the rising columns appear to be in the range of several tens of meters to a kilometer. One model for the mechanism to drive the plumes involves heating of nitrogen ice in a subsurface greenhouse environment; nitrogen gas pressurized by the solar heating explosively vents to the surface carrying clouds of ice and dark partides into the atmosphere. A temperature increase of less than 4 kelvins above the ambient surface value of 38 +/- 3 kelvins is more than adequate to drive the plumes to an 8-kilometer altitude. The mass flux in the trailing clouds is estimated to consist of up to 10 kilograms of fine dark particles per second or twice as much nitrogen ice and perhaps several hundred or more kilograms of nitrogen gas per second. Each eruption may last a year or more, during which on the order of a tenth of a cubic kilometer of ice is sublimed. PMID:17793016

  4. Energy sources for triton's geyser-like plumes

    USGS Publications Warehouse

    Brown, R.H.; Kirk, R.L.; Johnson, T.V.; Soderblom, L.A.

    1990-01-01

    Four geyser-like plumes were discovered near Triton's south pole in areas now in permanent sunlight. Because Triton's southern hemisphere is nearing a maximum summer solstice, insolation as a driver or a trigger for Triton's geyser-like plumes is an attractive hypothesis. Trapping of solar radiation in a translucent, low-conductivity surface layer (in a solid-state greenhouse), which is subsequently released in the form of latent heat of sublimation, could provide the required energy. Both the classical solid-state greenhouse consisting of exponentially absorbed insolation in a gray, translucent layer of solid nitrogen, and the "super" greenhouse consisting of a relatively transparent solid-nitrogen layer over an opaque, absorbing layer are plausible candidates. Geothermal heat may also play a part if assisted by the added energy input of seasonal cycles of insolation.

  5. Energy Sources for Triton's Geyser-Like Plumes.

    PubMed

    Brown, R H; Kirk, R L; Johnson, T V; Soderblom, L A

    1990-10-19

    Four geyser-like plumes were discovered near Triton's south pole in areas now in permanent sunlight. Because Triton's southern hemisphere is nearing a maximum summer solstice, insolation as a driver or a trigger for Triton's geyser-like plumes is an attractive hypothesis. Trapping of solar radiation in a translucent, low-conductivity surface layer (in a solid-state greenhouse), which is subsequently released in the form of latent heat of sublimation, could provide the required energy. Both the classical solid-state greenhouse consisting of exponentially absorbed insolation in a gray, translucent layer of solid nitrogen, and the "super" greenhouse consisting of a relatively transparent solid-nitrogen layer over an opaque, absorbing layer are plausible candidates. Geothermal heat may also play a part if assisted by the added energy input of seasonal cycles of insolation. PMID:17793021

  6. Energy sources for Triton's geyser-like plumes

    NASA Technical Reports Server (NTRS)

    Brown, R. H.; Johnson, T. V.; Kirk, R. L.; Soderblom, L. A.

    1990-01-01

    Four geyser-like plumes were discovered near Triton's south pole in areas now in permanent sunlight. Because Triton's southern hemisphere is nearing a maximum summer solstice, insolation as a driver or a trigger for Triton's geyser-like plumes is an attractive hypothesis. Trapping of solar radiation in a translucent, low-conductivity surface layer (in a solid-state greenhouse), which is subsequently released in the form of latent heat of sublimation, could provide the required energy. Both the classical solid-state greenhouse consisting of exponentially absorbed insolation in a gray, translucent layer of solid nitrogen, and the 'super' greenhouse consisting of a relatively transparent solid-nitrogen layer over an opaque, absorbing layer are plausible candidates. Geothermal heat may also play a part if assisted by the added energy input of seasonal cycles of insolation.

  7. Solar Activity and Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.

    2006-01-01

    Our Sun is a dynamic, ever-changing star. In general, its atmosphere displays major variation on an 11-year cycle. Throughout the cycle, the atmosphere occasionally exhibits large, sudden outbursts of energy. These "solar eruptions" manifest themselves in the form of solar flares, filament eruptions, coronal mass ejections (CMEs), and energetic particle releases. They are of high interest to scientists both because they represent fundamental processes that occur in various astrophysical context, and because, if directed toward Earth, they can disrupt Earth-based systems and satellites. Research over the last few decades has shown that the source of the eruptions is localized regions of energy-storing magnetic field on the Sun that become destabilized, leading to a release of the stored energy. Solar scientists have (probably) unraveled the basic outline of what happens in these eruptions, but many details are still not understood. In recent years we have been studying what triggers these magnetic eruptions, using ground-based and satellite-based solar observations in combination with predictions from various theoretical models. We will present an overview of solar activity and solar eruptions, give results from some of our own research, and discuss questions that remain to be explored.

  8. Eruption on Io

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This image, taken by NASA's Galileo spacecraft, shows a new blue-colored volcanic plume extending about 100 kilometers (about 60 miles) into space from Jupiter's moon Io (see inset at lower left). The blue color of the plume is consistent with the presence of sulfur dioxide gas and 'snow' condensing from the gas as the plume expands and cools. Galileo images have also shown that the Ra Patera plume glows in the dark, perhaps due to the fluorescence of sulfur and oxygen ions created by the breaking apart of sulfur dioxide molecules by energetic particles in the Jovian magnetosphere. The images at right show a comparison of changes seen near the volcano Ra Patera since the Voyager spacecraft flybys of 1979 (windows at right show Voyager image at top and Galileo image at bottom). This eruptive plume is an example of a new type of volcanic activity discovered during Voyager's flyby in 1979, believed to be geyser-like eruptions driven by sulfur dioxide or sulfur gas erupting and freezing in Io's extremely tenuous atmosphere. Volcanic eruptions on Earth cannot throw materials to such high altitudes. Ra Patera is the site of dramatic surface changes. An area around the volcano of about 40,000 square kilometers, area about the size of New Jersey, has been covered by new volcanic deposits. The image was taken in late June 28, 1996 from a distance of 972,000 kilometers (604,000 miles). The Galileo mission is managed by NASA's Jet Propulsion Laboratory.

  9. Active Volcanic Eruptions on Io

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Six views of the volcanic plume named Prometheus, as seen against Io's disk and near the bright limb (edge) of the satellite by the SSI camera on the Galileo spacecraft during its second (G2) orbit of Jupiter. North is to the top of each frame. To the south-southeast of Prometheus is another bright spot that appears to be an active plume erupting from a feature named Culann Patera. Prometheus was active 17 years ago during both Voyager flybys, but no activity was detected by Voyager at Culann. Both of these plumes were seen to glow in the dark in an eclipse image acquired by the imaging camera during Galileo's first (G1) orbit, and hot spots at these locations were detected by Galileo's Near-Infrared Mapping Spectrometer.

    The plumes are thought to be driven by heating sulfur dioxide in Io's subsurface into an expanding fluid or 'geyser'. The long-lived nature of these eruptions requires that a substantial supply of sulfur dioxide must be available in Io's subsurface, similar to groundwater. Sulfur dioxide gas condenses into small particles of 'snow' in the expanding plume, and the small particles scatter light and appear bright at short wavelengths. The images shown here were acquired through the shortest-wavelength filter (violet) of the Galileo camera. Prometheus is about 300 km wide and 75 km high and Culann is about 150 km wide and less than 50 km high. The images were acquired on September 4, 1996 at a range of 2,000,000 km (20 km/pixel resolution). Prometheus is named after the Greek fire god and Culann is named after the Celtic smith god.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the

  10. Solar Eruptions Initiated in Sigmoidal Active Regions

    NASA Astrophysics Data System (ADS)

    Savcheva, Antonia

    2016-07-01

    active regions that have been shown to possess high probability for eruption. They present a direct evidence of the existence of flux ropes in the corona prior to the impulsive phase of eruptions. In order to gain insight into their eruptive behavior and how they get destabilized we need to know their 3D magnetic field structure. First, we review some recent observations and modeling of sigmoidal active regions as the primary hosts of solar eruptions, which can also be used as useful laboratories for studying these phenomena. Then, we concentrate on the analysis of observations and highly data-constrained non-linear force-free field (NLFFF) models over the lifetime of several sigmoidal active regions, where we have captured their magnetic field structure around the times of major flares. We present the topology analysis of a couple of sigmoidal regions pointing us to the probable sites of reconnection. A scenario for eruption is put forward by this analysis. We demonstrate the use of this topology analysis to reconcile the observed eruption features with the standard flare model. Finally, we show a glimpse of how such a NLFFF model of an erupting region can be used to initiate a CME in a global MHD code in an unprecedented realistic manner. Such simulations can show the effects of solar transients on the near-Earth environment and solar system space weather.

  11. Volcanic eruptions and solar activity

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

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

  12. Active Eruptions in the NE Lau Basin

    NASA Astrophysics Data System (ADS)

    Resing, J. A.; Embley, R. W.

    2009-12-01

    NE Lau Response Team: K Rubin, E Baker, J Lupton, M Lilley, T Shank, S Merle, R Dziak, T Collasius (Jason 2 Expedition Leader), N Buck, T Baumberger, D Butterfield, D Clague, D Conlin, J Cowen, R Davis, L Evans, J Huber, M Keith, N Keller, P Michael, E Podowski, A-L Reysenbach, K Roe, H Thomas, S Walker. During a May 2009 cruise to W Mata volcano in the NE Lau Basin, we made the first observations of an active eruption on the deep-sea floor. The cruise was organized after volcanic activity was detected at two sites (W Mata volcano and NE Lau Spreading Center, NELSC) during a Nov. 2008 NOAA-PMEL expedition. At that time, both sites had elevated H2 concentrations and volcaniclastic shards in the hydrothermal plumes. Moored hydrophone data since Jan 2009 indicate that the activity at W Mata has been continuous between these expeditions. Results of our cruise and other work suggest that the NE Lau Basin hosts an unusually high level of magmatic activity, making it an ideal location to study the effects of magmatic processes on hydrothermal activity and associated ecosystems. W Mata was visited with 5 ROV Jason 2 dives and 2 dives with the MBARI autonomous mapping vehicle in May 2009. It was actively erupting at the 1200 m deep summit during each, so a hydrophone was deployed locally to collect acoustic data. Ship and shore-based analysis of HD video, molten lava, rocks, sediments, hot spring waters, and micro- and macro biological specimens collected by Jason 2 have provided a wealth of data. The eruption itself was characterized by extrusion of red, molten lava, extensive degassing, formation of large magma bubbles, explosive pyroclast ejection, and the active extrusion of pillow lavas. The erupting magmas are boninite, a relatively rare magma type found only at convergent margins. The hydrothermal fluids are generally acidic and all diffuse fluids collected were microbially active, even those at pH <3. W Mata was host to shrimp similar to those found at several other

  13. Geyser's Eruptive Activity in Broadband Seismic Records

    NASA Astrophysics Data System (ADS)

    Kugaenko, Yulia; Saltykov, Vadim

    2010-05-01

    A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapor phase (steam). The formation of geysers is due to particular hydrogeological conditions, which exist in only a few places on Earth, so they are a fairly rare phenomenon. The reasons of geyser periodicity and specifics of the activity for every particular geyser are not completely clear yet. So almost for all known geysers it is necessary to develop the personal model. In given study we first use seismic method for detection of possible hidden feature of geyser's eruptive activity in Kamchatkan Valley of the Geysers. Broadband seismic records of geyser generated signals were obtained in hydrothermal field. The Valley of the Geysers belongs to Kronotskiy State Natural Biosphere Reserve and the UNESCO World Natural Heritage Site "Volcanoes of Kamchatka". Neither seismological nor geophysical investigations were carried out here earlier. In September, 2009 seismic observation was organized in geyser's field by 24-bit digital output broadband seismometers (GURALP CMG-6TD flat velocity response 0.033-50 Hz). Four geysers were surveyed: the fountain type Big and Giant geysers; the cone type Pearl geyser and the short-period Gap geyser. Seismometers were set as possible close to the geyser's surface vent (usually at the distance near 3-5 m). Main parameters of the eruptions for the investigated geysers: - The Giant geyser is the most powerful among the regular active geysers in Kamchatkan Valley of the Geysers. The height of the fountain reaches 30 meters, the mass of water erupted is about 40-60 tons. The main cycle of activity varies significantly: in 1945 the intervals between eruptions was near 3 hours, nowadays it is 5-6 hours. As a geyser of fountain type, the Giant geyser erupts from the 2*3 m2 pool of water. - The Big geyser was flooded by the lake after the natural catastrophe (giant mud-stone avalanche, formed by landslide, bed into Geiyzernaya

  14. An experimental study of geyser-like flows induced by a pressurized air pocket

    NASA Astrophysics Data System (ADS)

    Elayeb, I. S.; Leon, A.; Choi, Y.; Alnahit, A. O.

    2015-12-01

    Previous studies argues that the entrapment of pressurized air pockets within combined sewer systems can produce geyser flows, which is an oscillating jetting of a mixture of gas-liquid flows. To verify that pressurized air pockets can effectively produce geysers, laboratory experiments were conducted. However, past experiments were conducted in relatively small-scale apparatus (i.e. maximum φ2" vertical shaft). This study conducted a set of experiments in a larger apparatus. The experimental setup consists of an upstream head tank, a downstream head tank, a horizontal pipe (46.5ft long, φ6") and a vertical pipe (10ft long, φ6"). The initial condition for the experiments is constant flow discharge through the horizontal pipe. The experiments are initiated by injecting an air pocket with pre-determined volume and pressure at the upstream end of the horizontal pipe. The air pocket propagates through the horizontal pipe until it arrives to the vertical shaft, where it is released producing a geyser-like flow. Three flow rates in the horizontal pipe and three injected air pressures were tested. The variables measured were pressure at two locations in the horizontal pipe and two locations in the vertical pipe. High resolution videos at two regions in the vertical shaft were also recorded. To gain further insights in the physics of air-water interaction, the laboratory experiments were complemented with numerical simulations conducted using a commercial 3D CFD model, previously validated with experiments.

  15. Geyser's Eruptive Activity in Broadband Seismic Records

    NASA Astrophysics Data System (ADS)

    Kugaenko, Yulia; Saltykov, Vadim

    2010-05-01

    A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapor phase (steam). The formation of geysers is due to particular hydrogeological conditions, which exist in only a few places on Earth, so they are a fairly rare phenomenon. The reasons of geyser periodicity and specifics of the activity for every particular geyser are not completely clear yet. So almost for all known geysers it is necessary to develop the personal model. In given study we first use seismic method for detection of possible hidden feature of geyser's eruptive activity in Kamchatkan Valley of the Geysers. Broadband seismic records of geyser generated signals were obtained in hydrothermal field. The Valley of the Geysers belongs to Kronotskiy State Natural Biosphere Reserve and the UNESCO World Natural Heritage Site "Volcanoes of Kamchatka". Neither seismological nor geophysical investigations were carried out here earlier. In September, 2009 seismic observation was organized in geyser's field by 24-bit digital output broadband seismometers (GURALP CMG-6TD flat velocity response 0.033-50 Hz). Four geysers were surveyed: the fountain type Big and Giant geysers; the cone type Pearl geyser and the short-period Gap geyser. Seismometers were set as possible close to the geyser's surface vent (usually at the distance near 3-5 m). Main parameters of the eruptions for the investigated geysers: - The Giant geyser is the most powerful among the regular active geysers in Kamchatkan Valley of the Geysers. The height of the fountain reaches 30 meters, the mass of water erupted is about 40-60 tons. The main cycle of activity varies significantly: in 1945 the intervals between eruptions was near 3 hours, nowadays it is 5-6 hours. As a geyser of fountain type, the Giant geyser erupts from the 2*3 m2 pool of water. - The Big geyser was flooded by the lake after the natural catastrophe (giant mud-stone avalanche, formed by landslide, bed into Geiyzernaya

  16. Analyses of Etna Eruptive Activity From 18th Century and Characterization of Flank Eruptions

    NASA Astrophysics Data System (ADS)

    del Carlo, P.; Branca, S.; Coltelli, M.

    2003-12-01

    Etna explosive activity has usually been considered subordinate with respect to the effusive eruptions. Nevertheless, in the last decade and overall after the 2001 and 2002 flank eruptions, explosive activity has drawn the attention of the scientific and politic communities owing to the damages that the long-lasting ash fall caused to Sicily's economy. We analyzed the eruptions from the 18th century to find some analogous behavior of Etna in the past. A study of the Etna historical record (Branca and Del Carlo, 2003) evidenced that after the 1727 eruption, there are no more errors in the attribution of the year of the eruption. Furthermore from this time on, the scientific quality of the chronicles allowed us to obtain volcanological information and to estimate the magnitude of the major explosive events. The main goal of this work was to characterize the different typologies of Etna eruptions in the last three centuries. Meanwhile, we have tried to find the possible relationship between the two kinds of activity (explosive and effusive) in order to understand the complexity of the eruptive phenomena and define the short-term behavior of Etna. On the base of the predominance of the eruptive typology (effusive or explosive) we have classified the flank eruptions in three classes: i) Type 1: almost purely effusive; ii) Type 2: the intensity of explosive activity comparable with the effusive; iii) Type 3: almost purely explosive with minor lava effusion (only the 1763 La Montagnola and 2002 eruptions belong to this class). Long-lasting explosive activity is produced by flank eruptions with continuous ash emission and prolonged fallout on the flanks (e.g. 1763, 1811, 1852-53, 1886, 1892, 2001 and 2002 eruptions). At summit craters continuous activity is weaker, whereas the strongest explosive eruptions are short-lived events. Furthermore, from the 18th to 20th century there were several years of intense and discontinuous summit explosive activity, from high strombolian

  17. 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.

  18. 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.

  19. Role of Internal Heat Source for Eruptive Plumes on Triton

    NASA Technical Reports Server (NTRS)

    Duxbury, N. S.; Brown, R. H.

    1996-01-01

    For the first time the role of the internal heat source, due to radioactive decay in Triton's core, is investigate with respect to geyser-like plumes...A new mechanism of energy supply to the Tritonian eruptive plumes is proposed...We present the critical values of these parameters for Triton. A possible origin of the subsurface vents on Triton is also suggested.

  20. Predicting eruptions from precursory activity using remote sensing data hybridization

    NASA Astrophysics Data System (ADS)

    Reath, K. A.; Ramsey, M. S.; Dehn, J.; Webley, P. W.

    2016-07-01

    Many volcanoes produce some level of precursory activity prior to an eruption. This activity may or may not be detected depending on the available monitoring technology. In certain cases, precursors such as thermal output can be interpreted to make forecasts about the time and magnitude of the impending eruption. Kamchatka (Russia) provides an ideal natural laboratory to study a wide variety of eruption styles and precursory activity prior to an eruption. At Bezymianny volcano for example, a clear increase in thermal activity commonly occurs before an eruption, which has allowed predictions to be made months ahead of time. Conversely, the eruption of Tolbachik volcano in 2012 produced no discernable thermal precursors before the large scale effusive eruption. However, most volcanoes fall between the extremes of consistently behaved and completely undetectable, which is the case with neighboring Kliuchevskoi volcano. This study tests the effectiveness of using thermal infrared (TIR) remote sensing to track volcanic thermal precursors using data from both the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Advanced Very High Resolution Radiometer (AVHRR) sensors. It focuses on three large eruptions that produced different levels and durations of effusive and explosive behavior at Kliuchevskoi. Before each of these eruptions, TIR spaceborne sensors detected thermal anomalies (i.e., pixels with brightness temperatures > 2 °C above the background temperature). High-temporal, low-spatial resolution (i.e., ~ hours and 1 km) AVHRR data are ideal for detecting large thermal events occurring over shorter time scales, such as the hot material ejected following strombolian eruptions. In contrast, high-spatial, low-temporal resolution (i.e., days to weeks and 90 m) ASTER data enables the detection of much lower thermal activity; however, activity with a shorter duration will commonly be missed. ASTER and AVHRR data are combined to track low

  1. 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.

  2. Trends in intrusive and eruptive activity during Kilauea's long-lived east rift zone eruption

    NASA Astrophysics Data System (ADS)

    Orr, T. R.; Patrick, M. R.; Heliker, C.

    2011-12-01

    Kilauea Volcano's Pu`u `O`o eruption, continuing for nearly three decades, offers a unique opportunity to study trends in eruptive behavior. One such trend, that of uprift intrusion ± eruption, accompanied by crater floor collapse and eruptive hiatus, has been repeated several times at Pu`u `O`o. This includes the February 7, 1993, intrusion; the January 29, 1997, intrusion and eruption; the September 12, 1999, intrusion; and the June 17, 2007, intrusion and eruption. Activity resumed within Pu`u `O`o following each of these events, and crater refilling culminated eventually in the outbreak of lava from new vents on the flank of the Pu`u `O`o cone. The pattern was repeated again in 2011, when a brief fissure eruption uprift from Pu`u `O`o started on March 5. The Pu`u `O`o crater floor dropped about 115 m in response to the eruption, which ceased on March 9. After a short hiatus, lava reappeared in Pu`u `O`o on March 26, and the crater began to fill slowly thereafter by overflow from a central lava lake. Starting in late June 2011, however, the crater floor began to uplift in a wholesale fashion, suggesting an increase in the pressure beneath the Pu`u `O`o edifice. By late July, the lava within the crater had reached its highest level since early 2004, and lava had begun to overflow from the southwestern side of the crater. On August 3, the west side of the Pu`u `O`o cone was abruptly thrust upward as a sill was injected beneath that portion of the cone. Within minutes, lava began to erupt from a crack on the west flank of Pu`u `O`o, completing the pattern of intrusion, crater collapse, refilling, and breakout. During a long-lived eruption, maintaining a detailed observational and geophysical record is essential for recognizing patterns that may emerge. Recognizing such a pattern allowed Hawaiian Volcano Observatory scientists to prepare a response well in advance of the August 3, 2011 event, and provides guidance for responding to future eruption crises at Pu`u `O

  3. Case study of a complex active-region filament eruption

    NASA Astrophysics Data System (ADS)

    Yan, X. L.; Qu, Z. Q.; Kong, D. F.; Deng, L. H.; Xue, Z. K.

    2013-09-01

    Context. We investigated a solar active-region filament eruption associated with a C6.6 class flare and a coronal mass ejection (CME) in NOAA active region 08858 on 2000 February 9. Aims: We aim to better understand the relationship between filament eruptions and the associated flares and CMEs. Methods: Using BBSO, SOHO/EIT, and TRACE observational data, we analyzed the process of the active-region filament eruption in the chromosphere and the corona. Using the SOHO/MDI magnetograms, we investigated the change of the magnetic fields in the photosphere. Using the GOES soft X-ray flux and the SOHO/LASCO images, we identified the flare and CME, which were associated with this active-region filament eruption. Results: The brightenings in the chromosphere are a precursor of the filament expansion. The eruption itself can be divided into four phases: In the initial phase, the intertwined bright and dark strands of the filament expand. Then, the bright strands are divided into three parts with different expansion velocity. Next, the erupting filament-carrying flux rope expands rapidly and combines with the lower part of the expanding bright strands. Finally, the filament erupts accompanied by other dark strands overlying the filament.The overlying magnetic loops and the expansion of the filament strands can change the direction of the eruption. Conclusions: The time delay between the velocity peaks of the filament and that of the two parts of the bright strands clearly demonstrates that the breakup of the bright loops tying on the filament into individual strands is important for its eruption. The eruption is a collection of multiple processes that are physically coupled rather than a single process.

  4. Eruptions that Drive Coronal Jets in a Solar Active Region

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

    2016-01-01

    Solar coronal jets are common in both coronal holes and in active regions (e.g., Shibata et al. 1992, Shimojo et al. 1996, Cirtain et al. 2007. Savcheva et al. 2007). Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism (e.g. Yokoyama & Shibata 1995). We present observations of an on-disk active region (NOAA AR 11513) that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale 20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode. A full report of this study appears in Sterling et al. (2016).

  5. Can vesicle size distributions predict eruption intensity during volcanic activity?

    NASA Astrophysics Data System (ADS)

    LaRue, A.; Baker, D. R.; Polacci, M.; Allard, P.; Sodini, N.

    2013-06-01

    We studied three-dimensional (3-D) vesicle size distributions by X-ray microtomography in scoria collected during the relatively quiescent Phase II of the 2010 eruption at Eyjafjallajökull volcano, Iceland. Our goal was to compare the vesicle size distributions (VSDs) measured in these samples with those found in Stromboli volcano, Italy. Stromboli was chosen because its VSDs are well-characterized and show a correlation with eruption intensity: typical Strombolian activity produces VSDs with power-law exponents near 1, whereas larger and more energetic Vulcanian-type explosions and Plinian eruptions produce VSDs with power-law exponents near 1.5. The hypothesis to be tested was whether or not the samples studied in this work would contain VSDs similar to normal Strombolian products, display higher power-law exponents, or be described by exponential functions. Before making this comparison we tested the hypothesis that the phreatomagmatic nature of the Eyjafjallajökull eruption might have a significant effect on the VSDs. We performed 1 atm bubble-growth experiments in which the samples were inundated with water and compared them to similar, control, experiments without water inundation. No significant differences between the VSDs of the two sets of experiments were found, and the hypothesis is not supported by the experimental evidence; therefore, VSDs of magmatic and phreatomagmatic eruptions can be directly compared. The Phase II Eyjafjallajökull VSDs are described by power law exponents of ~ 0.8, typical of normal Strombolian eruptions. The comparable VSDs and behavior of Phase II of the Eyjafjallajökull 2010 eruption to Stromboli are interpreted to be a reflection of similar conduit systems in both volcanoes that are being constantly fed by the ascent of deep magma that mixes with resident magma at shallow depths. Such behavior implies that continued activity during Phase II of the Eyjafjallajökull eruption could be expected and would have been predicted

  6. Temperature and Structure of Active Eruptions from a Handheld Camcorder

    NASA Astrophysics Data System (ADS)

    Radebaugh, Jani; Carling, Greg T.; Saito, Takeshi; Dangerfield, Anne; Tingey, David G.; Lorenz, Ralph D.; Lopes, Rosaly M.; Howell, Robert R.; Diniega, Serina; Turtle, Elizabeth P.

    2014-11-01

    A commercial handheld digital camcorder can operate as a high-resolution, short-wavelength, low-cost thermal imaging system for monitoring active volcanoes, when calibrated against a laboratory heated rock of similar composition to the given eruptive material. We utilize this system to find full pixel brightness temperatures on centimeter scales at close but safe proximity to active lava flows. With it, observed temperatures of a Kilauea tube flow exposed in a skylight reached 1200 C, compared with pyrometer measurements of the same flow of 1165 C, both similar to reported eruption temperatures at that volcano. The lava lake at Erta Ale, Ethiopia had crack and fountain temperatures of 1175 C compared with previous pyrometer measurements of 1165 C. Temperature calibration of the vigorously active Marum lava lake in Vanuatu is underway, challenges being excessive levels of gas and distance from the eruption (300 m). Other aspects of the fine-scale structure of the eruptions are visible in the high-resolution temperature maps, such as flow banding within tubes, the thermal gradient away from cracks in lake surfaces, heat pathways through pahoehoe crust and temperature zoning in spatter and fountains. High-resolution measurements such as these reveal details of temperature, structure, and change over time at the rapidly evolving settings of active lava flows. These measurement capabilities are desirable for future instruments exploring bodies with active eruptions like Io, Enceladus and possibly Venus.

  7. Can vesicle size distributions assess eruption intensity during volcanic activity?

    NASA Astrophysics Data System (ADS)

    LaRue, A.; Baker, D. R.; Polacci, M.; Allard, P.; Sodini, N.

    2013-10-01

    We studied three-dimensional (3-D) vesicle size distributions by X-ray microtomography in scoria collected during the relatively quiescent Phase II of the April-May 2010 eruption at Eyjafjallajökull volcano, Iceland. Our goal was to compare cumulative vesicle size distributions (VSDs) measured in these samples with those found in Stromboli volcano, Italy. Stromboli was chosen because its VSDs are well-characterized and show a correlation with eruption intensity: typical Strombolian activity produces VSDs with power-law exponents near 1, whereas larger and more energetic vulcanian-type explosions and Plinian eruptions produce VSDs with power-law exponents near 1.5. The first hypothesis to be tested was whether or not the samples studied in this work would contain VSDs similar to normal Strombolian products, display higher power-law exponents, or be described by exponential functions. Before making this comparison, we tested a second hypothesis, which was that the magma-water interactions in the Eyjafjallajökull eruption might have a significant effect on the VSDs. We performed 1 bar bubble-growth experiments in which the samples were inundated with water and compared them to similar control experiments without water inundation. No significant differences between the VSDs of the two sets of experiments were found, and the second hypothesis is not supported by the experimental evidence. The Phase II Eyjafjallajökull VSDs are described by power-law exponents of ~0.8, typical of normal Strombolian eruptions, and support the first hypothesis. The comparable VSDs and behavior of Phase II of the Eyjafjallajökull 2010 eruption to Stromboli are interpreted to be a reflection of similar conduit systems in both volcanoes that are being constantly fed by the ascent of mingled/mixed magma from depth. Such behavior implies that continued activity during Phase II of the Eyjafjallajökull eruption could be expected and would have been predicted, had our VSDs been measured in

  8. A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

    NASA Astrophysics Data System (ADS)

    Jiang, Chao-Wei; Wu, Shi-Tsan; Feng, Xue-Shang; Hu, Qiang

    2016-01-01

    Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE-MHD-NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption.

  9. Hinode Observations of an Eruption from a Sigmoidal Active Region

    NASA Astrophysics Data System (ADS)

    Green, L. M.; Wallace, A. J.; Kliem, B.

    2012-08-01

    We analyse the evolution of a bipolar active region which produces an eruption during its decay phase. The soft X-ray arcade develops high shear over a time span of two days and transitions to sigmoidal shortly before the eruption. We propose that the continuous sigmoidal soft X-ray threads indicate that a flux rope has formed which is lying low in the solar atmosphere with a bald patch separatrix surface topology. The formation of the flux rope is driven by the photospheric evolution which is dominated by fragmentation of the main polarities, motion due to supergranular flows and cancellation at the polarity inversion line.

  10. 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.

  11. Lightning and electrical activity during the eruption of Mt. Augustine

    NASA Astrophysics Data System (ADS)

    Thomas, R. J.; Krehbiel, P.; Rison, W.; Aulich, G.; Edens, H.; McNutt, S.; Tytgat, G.; Clark, E.

    2006-12-01

    Lightning during several of the eruptions were observed using a technique that we use to observe thunderstorms. Very high frequency radio emissions (60 MHz) emitted by electrical discharges are located by their times of arrival at several receiving stations. In a typical thunderstorm lightning flash we locate several thousand events giving a 3-D map of the lightning. In mid January we set up two stations about 100 km east of the volcano, near Homer, AK. We received and located the source of thousands of radio emissions from the vicinity of Mt Augustine during the January 28 eruption. With two stations we were able to determine the azimuthal direction to the sources, their power, the time history and relationship to other pulses. On one lightning flash we used an interferometric effect to infer altitude. We observed two distinct forms of electrical activity. The first was many short bursts (less than a milliseconds) that occurred coincident with the explosive eruption. These seemed to be short discharges (up to several hundred meters) that occur just as the material leaves the volcano. The other type was very similar to the lightning that we see in thunderstorms. Most of these lightning flashes began several minutes after the explosive eruption began. Following the largest eruption on January 28 we observed about 300 discharges in a period lasting 11 minutes. Initially these flashes lasted only a few milliseconds, but the final ones lasted more than one half second, had many branches 10's of km in length. Most or all of this lightning was in the plume. Because of the bad weather there were no visual observations. Previous detection of volcanic lightning has been visually or by low frequency radio emissions that detect only the lightning that comes to the ground. These initial observations show that this technique has great potential to detect explosive eruptions and study the details of lightning and the charge structure in the plume.

  12. 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

  13. 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.

  14. 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.

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

    USGS Publications Warehouse

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

    2007-01-01

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

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

    PubMed

    Thomas, R J; Krehbiel, P R; Rison, W; Edens, H E; Aulich, G D; Winn, W P; McNutt, S R; Tytgat, G; Clark, E

    2007-02-23

    By using a combination of radio frequency time-of-arrival and interferometer measurements, we observed a sequence of lightning and electrical activity during one of Mount St. Augustine's eruptions. The observations indicate that the electrical activity had two modes or phases. First, there was an explosive phase in which the ejecta from the explosion appeared to be highly charged upon exiting the volcano, resulting in numerous apparently disorganized discharges and some simple lightning. The net charge exiting the volcano appears to have been positive. The second phase, which followed the most energetic explosion, produced conventional-type discharges that occurred within plume. Although the plume cloud was undoubtedly charged as a result of the explosion itself, the fact that the lightning onset was delayed and continued after and well downwind of the eruption indicates that in situ charging of some kind was occurring, presumably similar in some respects to that which occurs in normal thunderstorms. PMID:17322054

  17. A Comparison Study of an Active Region Eruptive Filament and a Neighboring Non-Eruptive Filament

    NASA Astrophysics Data System (ADS)

    Wu, S. T.; Jiang, C.; Feng, X. S.; Hu, Q.

    2014-12-01

    We perform a comparison study of an eruptive filament in the core region of AR 11283 and a nearby non-eruptive filament. The coronal magnetic field supporting these two filaments is extrapolated using our data-driven CESE-MHD-NLFFF code (Jiang et al. 2013, Jiang etal. 2014), which presents two magnetic flux ropes (FRs) in the same extrapolation box. The eruptive FR contains a bald-patch separatrix surface (BPSS) spatially co-aligned very well with a pre-eruption EUV sigmoid, which is consistent with the BPSS model for the coronal sigmoids. The numerically reproduced magnetic dips of the FRs match observations of the filaments strikingly well, which supports strongly the FR-dip model for filaments. The FR that supports the AR eruptive filament is much smaller (with a length of 3 Mm) compared with the large-scale FR holding the quiescent filament (with a length of 30 Mm). But the AR eruptive FR contains most of the magnetic free energy in the extrapolation box and holds a much higher magnetic energy density than the quiescent FR, because it resides along the main polarity inversion line (PIL) around sunspots with strong magnetic shear. Both the FRs are weakly twisted and cannot trigger kink instability. The AR eruptive FR is unstable because its axis reaches above a critical height for torus instability (TI), at which the overlying closed arcades can no longer confine the FR stably. To the contrary, the quiescent FR is firmly held down by its overlying field, as its axis apex is far below the TI threshold height. (This work is partially supported by NSF AGS-1153323 and 1062050)

  18. MAGNETOHYDRODYNAMIC SIMULATION OF A SIGMOID ERUPTION OF ACTIVE REGION 11283

    SciTech Connect

    Jiang Chaowei; Feng Xueshang; Wu, S. T.; Hu Qiang E-mail: fengx@spaceweather.ac.cn E-mail: qh0001@uah.edu

    2013-07-10

    Current magnetohydrodynamic (MHD) simulations of the initiation of solar eruptions are still commonly carried out with idealized magnetic field models, whereas the realistic coronal field prior to eruptions can possibly be reconstructed from the observable photospheric field. Using a nonlinear force-free field extrapolation prior to a sigmoid eruption in AR 11283 as the initial condition in an MHD model, we successfully simulate the realistic initiation process of the eruption event, as is confirmed by a remarkable resemblance to the SDO/AIA observations. Analysis of the pre-eruption field reveals that the envelope flux of the sigmoidal core contains a coronal null and furthermore the flux rope is prone to a torus instability. Observations suggest that reconnection at the null cuts overlying tethers and likely triggers the torus instability of the flux rope, which results in the eruption. This kind of simulation demonstrates the capability of modeling the realistic solar eruptions to provide the initiation process.

  19. 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

  20. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania. II. Eruptive behaviour during the 2007-2008 explosive eruptions

    NASA Astrophysics Data System (ADS)

    Kervyn, Matthieu; Ernst, Gerald G. J.; Keller, Jörg; Vaughan, R. Greg; Klaudius, Jurgis; Pradal, Evelyne; Belton, Frederic; Mattsson, Hannes B.; Mbede, Evelyne; Jacobs, Patric

    2010-10-01

    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.

  1. The Variation of Volcanic Tremor During Active Stage in the 1986 Izu-Oshima Eruption

    NASA Astrophysics Data System (ADS)

    Kurokawa, Aika; Kurita, Kei

    2014-05-01

    Izu-Oshima is one of the most active volcanoes in Japan. The latest eruption of Nov. 1986 exhibited a curious eruption sequence; the strombolian type eruption started on 15 Nov. at the central vent and it had continued for 4 days. Then after it ceased, subplinian type fissure eruptions occurred inside and outside the caldera where several hundreds meters to few kilometers away from the central vent. Lava flows were associated with these two eruption episodes. Petrologically compositions of these two kinds of lava are completely dissimilar; magma from the central vent is basaltic with narrow range of chemical composition, which is almost same as that of the previous stages while magma from the fissures is evolved one with wider variations of composition [Aramaki and Fujii, 1988]. This means that two distinct magma sources, which were chemically separated but mechanically coupled, should have existed prior to the eruption. The most important issue concerning this eruption is how the mechanical interaction between two magma sources took place and evolved. Throughout the eruption sequence, remarkable activities of seismic tremor have been observed. In this presentation we report evolution of tremor sources to characterize the interaction based on the recently recovered seismic records and we propose a reinterpretation of the eruption sequence. We analyzed volcanic tremor in Nov. 1986 on digitized seismic records of 7 stations in the Island. The aim of this analysis is to estimate the movement of two kinds of magma associated with the change of the eruption styles. Firstly root mean square amplitudes of the filtered seismic signals and their spectrum were calculated. The tremor style changed from continuous mode to intermittent, sporadic mode at the period between the summit eruption and the fissure eruptions. The dominant frequency also changed around the same time. Secondly to derive the location of tremor source, Amplitude Inversion Method [Battaglia and Aki, 2003

  2. 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

  3. Triggering of major eruptions recorded by actively forming cumulates

    PubMed Central

    Stock, Michael J.; Taylor, Rex N.; Gernon, Thomas M.

    2012-01-01

    Major overturn within a magma chamber can bring together felsic and mafic magmas, prompting de-volatilisation and acting as the driver for Plinian eruptions. Until now identification of mixing has been limited to analysis of lavas or individual crystals ejected during eruptions. We have recovered partially developed cumulate material (‘live’ cumulate mush) from pyroclastic deposits of major eruptions on Tenerife. These samples represent “frozen” clumps of diverse crystalline deposits from all levels in the developing reservoir, which are permeated with the final magma immediately before eruptions. Such events therefore record the complete disintegration of the magma chamber, leading to caldera collapse. Chemical variation across developing cumulus crystals records changes in melt composition. Apart from fluctuations reflecting periodic influxes of mafic melt, crystal edges consistently record the presence of more felsic magmas. The prevalence of this felsic liquid implies it was able to infiltrate the entire cumulate pile immediately before each eruption. PMID:23066500

  4. Triggering of major eruptions recorded by actively forming cumulates.

    PubMed

    Stock, Michael J; Taylor, Rex N; Gernon, Thomas M

    2012-01-01

    Major overturn within a magma chamber can bring together felsic and mafic magmas, prompting de-volatilisation and acting as the driver for Plinian eruptions. Until now identification of mixing has been limited to analysis of lavas or individual crystals ejected during eruptions. We have recovered partially developed cumulate material ('live' cumulate mush) from pyroclastic deposits of major eruptions on Tenerife. These samples represent "frozen" clumps of diverse crystalline deposits from all levels in the developing reservoir, which are permeated with the final magma immediately before eruptions. Such events therefore record the complete disintegration of the magma chamber, leading to caldera collapse. Chemical variation across developing cumulus crystals records changes in melt composition. Apart from fluctuations reflecting periodic influxes of mafic melt, crystal edges consistently record the presence of more felsic magmas. The prevalence of this felsic liquid implies it was able to infiltrate the entire cumulate pile immediately before each eruption. PMID:23066500

  5. Holocene eruptive activity of El Chichón Volcano, Chiapas, Mexico

    USGS Publications Warehouse

    Tilling, Robert I.; Rubin, Meyer; Sigurdsson, Haraldur; Carey, Steven; Duffield, Wendell A.; Rose, William I., Jr.

    1984-01-01

    Geologic and radiometric-age data indicate that El Chichón 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 dome-growth processes, were apparently separated by intervals of approximately 350 to 650 years. Some of El Chichón's eruptions may correlate with unusual atmospheric phenomena around A.D. 1300 and possibly A.D. 623.

  6. Seismic activity before and after the eruption of Kuchinoerabujima in 2015

    NASA Astrophysics Data System (ADS)

    Chiba, K.

    2015-12-01

    Shindake, on Kuchinoerabujima, in the Ryukyu Islands, south of Kyusyu, Japan, erupted at 09:59 JST on 29 May 2015. This eruption is considered to have been a phreato-magmatic eruption, according to the Coordinating Committee for Prediction of Volcanic Eruption in Japan. As characteristic seismic activities before and after the eruption, an A-type event (Mw 2.3) occurred in the northwestern part of Shindake on 23 May, and numerous volcanic events occurred in and around Shindake just after the eruption. The frequency-magnitude distribution (b-value) of earthquakes is commonly high in volcanic areas. It is also known that high b-values in volcanic areas are primarily responsible for material heterogeneity, low shear strength, and high thermal gradients. These facts suggest that the b-value distribution can be used as a tool to locate active magma chambers. It is thus important to determine the distribution of hypocenters precisely and to investigate the b-value distribution on Kuchinoerabujima. We used a data set of the Japan Meteorological Agency and the National Research Institute for Earth Science and Disaster Prevention, and a half-space with Vp = 2.5 km/s as a velocity structure. For the determination of hypocenters, we used the hypomh (Hirata and Matsu'ura 1987) and hypoDD (Waldhauser and Ellsworth 2000) algorithms. This revealed that many estimated hypocenters were distributed in and around the vent at a depth of ~5 km under Shindake before and after the eruption. A volume of high b (>1.2) was locally observed in the eastern part at depths of 1.0-2.5 km below Shindake before the eruption and another was widely observed at depths of 2.0-4.0 km after the eruption. By comparing these findings with other observation results, we may be able to obtain a clear image of the active magma chamber.

  7. 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

  8. ASTER Observations of Recent Thermal Activity and Explosive Eruption at Oldoinyo Lengai, Tanzania

    NASA Astrophysics Data System (ADS)

    Vaughan, R. G.; Abrams, M. J.; Kervyn, M.; Hook, S. J.

    2007-12-01

    Oldoinyo Lengai (OL) is the only active volcano in the world that produces natro-carbonatite lava. These carbonate-rich lavas are unique in that they have relatively low temperatures (500-600 C) compared with typical silicate lavas (600-1100 C), and they have a low viscosity, behaving more like a mud flow than a lava flow. OL has been erupting on and off since 1983, mostly resulting in small lava flows, pools and spatter cones (hornitos) confined to the summit crater. Explosive, ash-producing eruptions here are rare, however, an ASTER observation from September 4, 2007 caught the first satellite image of an ash plume erupting from OL, which may be indicative of a new phase of more silica-rich products and explosive activity that has not occurred here since the 1960s. Thermal infrared satellite monitoring has detected an increasing number of thermal anomalies around OL in recent months. MODIS MODVOLC data detected >30 hot spots in the last week of August and first week of September 2007, some of which may have been brush fires started by lava flows or spatter; ASTER detected the appearance of an anomalous hot spot at the summit of OL as early as mid-June. We will present up-to date information about the progress of the eruption and results from the analysis of the spectral composition of new eruption products and thermal anomalies that occurred prior to the recent explosive eruption. OL is one of many volcanoes in the world, and especially Africa, that is not regularly monitored. It is only through sporadic reports from locals or tourists in the area, and satellite data that we know anything at all about this volcanic eruption. Continued satellite monitoring along with studies of past thermal activity will help determine how future eruptions may be forecasted.

  9. Minifilament Eruptions that Drive Coronal Jets in a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

    2016-04-01

    We present observations of eruptive events in an active region adjacent to an on-disk coronal hole on 2012 June 30, primarily using data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), SDO/Helioseismic and Magnetic Imager (HMI), and STEREO-B. One eruption is of a large-scale (∼100″) filament that is typical of other eruptions, showing slow-rise onset followed by a faster-rise motion starting as flare emissions begin. It also shows an “EUV crinkle” emission pattern, resulting from magnetic reconnections between the exploding filament-carrying field and surrounding field. Many EUV jets, some of which are surges, sprays and/or X-ray jets, also occur in localized areas of the active region. We examine in detail two relatively energetic ones, accompanied by GOES M1 and C1 flares, and a weaker one without a GOES signature. All three jets resulted from small-scale (∼20″) filament eruptions consistent with a slow rise followed by a fast rise occurring with flare-like jet-bright-point brightenings. The two more-energetic jets showed crinkle patters, but the third jet did not, perhaps due to its weakness. Thus all three jets were consistent with formation via erupting minifilaments, analogous to large-scale filament eruptions and to X-ray jets in polar coronal holes. Several other energetic jets occurred in a nearby portion of the active region; while their behavior was also consistent with their source being minifilament eruptions, we could not confirm this because their onsets were hidden from our view. Magnetic flux cancelation and emergence are candidates for having triggered the minifilament eruptions.

  10. Volcanic eruption source parameters from active and passive microwave sensors

    NASA Astrophysics Data System (ADS)

    Montopoli, Mario; Marzano, Frank S.; Cimini, Domenico; Mereu, Luigi

    2016-04-01

    It is well known, in the volcanology community, that precise information of the source parameters characterising an eruption are of predominant interest for the initialization of the Volcanic Transport and Dispersion Models (VTDM). Source parameters of main interest would be the top altitude of the volcanic plume, the flux of the mass ejected at the emission source, which is strictly related to the cloud top altitude, the distribution of volcanic mass concentration along the vertical column as well as the duration of the eruption and the erupted volume. Usually, the combination of a-posteriori field and numerical studies allow constraining the eruption source parameters for a given volcanic event thus making possible the forecast of ash dispersion and deposition from future volcanic eruptions. So far, remote sensors working at visible and infrared channels (cameras and radiometers) have been mainly used to detect, track and provide estimates of the concentration content and the prevailing size of the particles propagating within the ash clouds up to several thousand of kilometres far from the source as well as track back, a-posteriori, the accuracy of the VATDM outputs thus testing the initial choice made for the source parameters. Acoustic wave (infrasound) and microwave fixed scan radar (voldorad) were also used to infer source parameters. In this work we want to put our attention on the role of sensors operating at microwave wavelengths as complementary tools for the real time estimations of source parameters. Microwaves can benefit of the operability during night and day and a relatively negligible sensitivity to the presence of clouds (non precipitating weather clouds) at the cost of a limited coverage and larger spatial resolution when compared with infrared sensors. Thanks to the aforementioned advantages, the products from microwaves sensors are expected to be sensible mostly to the whole path traversed along the tephra cloud making microwaves particularly

  11. Minifilament Eruptions that Drive Coronal Jets in a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David; Panesar, Navdeep; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

    2016-05-01

    Solar coronal jets are common in both coronal holes and in active regions. Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism, such as the hitherto popular ``emerging flux'' model for jets. We present observations of an on-disk active region that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale ~20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode.

  12. 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

  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. 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

  15. 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

  16. 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.

  17. Monitoring Eruptive Activity at Mount St. Helens with TIR Image Data

    NASA Technical Reports Server (NTRS)

    Vaughan, R. G.; Hook, S. J.; Ramsey, M. S.; Realmuto, V. J.; Schneider, D. J.

    2005-01-01

    Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre-eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum temperatures of similar to approximately 330 C and TIR data acquired concurrently from a Forward Looking Infrared (FLIR) camera showed maximum temperatures similar to approximately 675 C, in narrow (approximately 1-m) fractures of molten rock on a new resurgent dome. MASTER and FLIR thermal flux calculations indicated a radiative cooling rate of approximately 714 J/m(exp 2)/s over the new dome, corresponding to a radiant power of approximately 24 MW. MASTER data indicated the new dome was dacitic in composition, and digital elevation data derived from LIDAR acquired concurrently with MASTER showed that the dome growth correlated with the areas of elevated temperatures. Low SO2 concentrations in the plume combined with sub-optimal viewing conditions prohibited quantitative measurement of plume SO2. The results demonstrate that airborne TIR data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes. Given sufficient resources, the airborne instrumentation could be deployed rapidly to a newly-awakening volcano and provide a means for remote volcano monitoring.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Formation and Eruption of an Active Region Sigmoid: NLFFF Modeling and MHD Simulation

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Wu, S.; Feng, X.; Hu, Q.

    2013-12-01

    We present a magnetic analysis of the formation and eruption of an active region sigmoid in AR 11283 from 2011 September 4 to 6, which is jointly based on observations, static nonlinear force-free field (NLFFF) extrapolation and dynamic MHD simulation. A time sequence of NLFFF model's outputs are used to reproduce the evolution of the magnetic field of the region over three days leading to a X-class flare near the end of 2011 September 6. In the first day, a new bipolar emerges into the negative polarity of a pre-existing mature bipolar, forming a magnetic topology with a coronal null on the magnetic separatrix surface between the two flux system, while the field is still near potential at the end of the day. After then photospheric shearing and twisting build up non-potentiality in the embedded core region, with a flux rope (FR) formed there above the polarity inversion line by tether-cutting reconnection between the strongly sheared field lines. Within this duration, the core field has gained a magnetic free energy of ˜ 1032 erg. In this core a sigmoid is observed distinctly at 22:00 UT on September 6, closely before its eruption at 22:12 UT. Comparison of the SDO/AIA observations with coronal magnetic field suggests that the sigmoid is formed by emission due to enhanced current sheet along the BPSS (bald-patch separatrix surface, in which the field lines graze the line-tied photosphere at the neutral line) that separates the FR from the ambient flux. Quantitative inspection of the pre-eruption field on 22:00 UT suggests a mechanism for the eruption: tether cutting at the null triggers a torus instability of the FR--overlying field system. This pre-eruption NLFFF is then input into a time-dependent MHD model to simulate the fast magnetic evolution during eruption, which successfully reproduces the observations. The highly asymmetric magnetic environment along with the lateral location of the null leads to a strongly inclined non-radial direction of the eruption

  3. Eruption dynamics at the active Santiaguito Dome inferred from a multidisciplinary geophysical experiment

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Varley, N.; Sanderson, R.; Gerst, A.; Lees, J.; Dalton, M.; Marcillo, O.; Every, S.; Normand, J.; Ruiz, M.

    2007-05-01

    Santiaguito Dome, which lies in the shadow of its parent stratovolcano (Santa Maria, Guatemala), has been effusing and exploding for more than eight decades. Pyroclastic emissions from the currently active Caliente Vent are characterized by ash and ballistic-rich emissions at least every hour, with vapor plumes that reach more than a kilometer above the vent. Such activity is recently accompanied by slow effusion of a dacitic block lava flow, which overtops the shallow 200-m-diameter crater and flows down the flanks of the cone. We are studying the mechanics of this explosive activity with an arsenal of geophysical sensors because of the unparalleled view into the crater from the Santa Maria summit vantage 1200 m above. Data collected in January 2007 provides us with the opportunity to quantify the energy budget for small-magnitude pyroclastic eruptions involving a silica-rich (dacitic) magma. Specifically, we are integrating seismic, infrasonic, thermal imaging, gas flux (SO2) imaging, high resolution video, and doppler radar observations to assess the temporal chronology of an eruption beginning with pre-eruption seismicity (apparent a few seconds to tens of seconds before the eruption onset), followed by subsequent infrasound radiation, and multi-phase material flux out through the vent. We are integrating these diverse data streams with the goal to better understand the location of various elastic energy sources and to provide more insight into the complex geometry of the crater and conduit system. Integrated measurements are used to assess the kinetic energy and thermal flux with an end goal of using elastic wavefield studies to remotely quantify eruption intensity at this type of potentially hazardous volcano.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  5. A statistical study of the subsurface structure and eruptivity of solar active regions

    NASA Astrophysics Data System (ADS)

    Lin, C.-H.

    2014-08-01

    A statistical study of 77 solar active regions (ARs) is conducted to investigate the existence of identifiable correlations between the subsurface structural disturbances and the activity level of the active regions. The disturbances examined in this study are <| δΓ 1/ Γ 1|>, <| δc 2/ c 2|>, and <| δc 2/ c 2- δΓ 1/ Γ 1|>, where Γ 1 and c are the thermodynamic properties of first adiabatic index and sound speed modified by magnetic field, respectively. The averages are over three depth layers: 0.975-0.98 R ⊙, 0.98-0.99 R ⊙ and 0.99-0.995 R ⊙ to represent the structural disturbances in that layer. The level of the surface magnetic activity is measured by the Magnetic Activity Index (MAI) of active region and the relative and absolute MAI differences (rdMAI and dMAI) between the active and quiet regions. The eruptivity of each active region is quantified by its Flare Index, total number of coronal mass ejections (CMEs), and total kinetic energy of the CMEs. The existence and level of the correlations are evaluated by scatter plots and correlation coefficients. No definitive correlation can be claimed from the results. While a weak positive trend is visible between dMAI and <| δΓ 1/ Γ 1|> and <| δc 2/ c 2|> in the layer 0.975-0.98 R ⊙, their correlation levels, being approximately 0.6, are not sufficiently high to justify the correlation. Some subsurface disturbances are seen to increase with eruptivity indices among ARs with high eruptivity. The statistical significance of such trend, however, cannot be ascertained due to the small number of very eruptive ARs in our sample.

  6. Solar Magnetic Activity Cycles, Coronal Potential Field Models and Eruption Rates

    NASA Astrophysics Data System (ADS)

    Petrie, G. J. D.

    2013-05-01

    We study the evolution of the observed photospheric magnetic field and the modeled global coronal magnetic field during the past 3 1/2 solar activity cycles observed since the mid-1970s. We use synoptic magnetograms and extrapolated potential-field models based on longitudinal full-disk photospheric magnetograms from the National Solar Observatory's three magnetographs at Kitt Peak, the Synoptic Optical Long-term Investigations of the Sun vector spectro-magnetograph, the spectro-magnetograph and the 512-channel magnetograph instruments, and from Stanford University's Wilcox Solar Observatory. The associated multipole field components are used to study the dominant length scales and symmetries of the coronal field. Polar field changes are found to be well correlated with active fields over most of the period studied, except between 2003 and 2006 when the active fields did not produce significant polar field changes. Of the axisymmetric multipoles, only the dipole and octupole follow the poles whereas the higher orders follow the activity cycle. All non-axisymmetric multipole strengths are well correlated with the activity cycle. The tilt of the solar dipole is therefore almost entirely due to active-region fields. The axial dipole and octupole are the largest contributors to the global field except while the polar fields are reversing. This influence of the polar fields extends to modulating eruption rates. According to the Computer Aided CME Tracking, Solar Eruptive Event Detection System, and Nobeyama radioheliograph prominence eruption catalogs, the rate of solar eruptions is found to be systematically higher for active years between 2003 and 2012 than for those between 1997 and 2002. This behavior appears to be connected with the weakness of the late-cycle 23 polar fields as suggested by Luhmann. We see evidence that the process of cycle 24 field reversal is well advanced at both poles.

  7. Solar magnetic activity cycles, coronal potential field models and eruption rates

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon

    2013-07-01

    We study the evolution of the observed photospheric magnetic field and the modeled global coronal magnetic field during the past 3 1/2 solar activity cycles observed since the mid-1970s. We use synoptic magnetograms and extrapolated potential-field models based on longitudinal full-disk photospheric magnetograms from the NSO's three magnetographs at Kitt Peak, the Synoptic Optical Long-term Investigations of the Sun (SOLIS) vector spectro-magnetograph (VSM), the spectro-magnetograph and the 512-channel magnetograph instruments, and from the U. Stanford's Wilcox Solar Observatory. The associated multipole field components are used to study the dominant length scales and symmetries of the coronal field. Of the axisymmetric multipoles, only the dipole and octupole follow the poles whereas the higher orders follow the activity cycle. All non-axisymmetric multipole strengths are well correlated with the activity cycle. The axial dipole and octupole are the largest contributors to the global field except while the polar fields are reversing. This influence of the polar fields extends to modulating eruption rates. According to the Computer Aided CME Tracking (CACTus), Solar Eruptive Event Detection System (SEEDS), and Nobeyama radioheliograph prominence eruption catalogs, the rate of solar eruptions is found to be systematically higher for active years between 2003-2012 than for those between 1997-2002. This behavior appears to be connected with the weakness of the late-cycle 23 polar fields as suggested by Luhmann. We see evidence that the process of cycle 24 field reversal is well advanced at both poles.

  8. 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

  9. Eruption of the magnetic flux rope in a fast decayed active region

    NASA Astrophysics Data System (ADS)

    Yang, Shangbin

    2012-07-01

    An isolated and fast decayed active region was observed when passing through solar disk. There is only one CME related with it that give us a good opportunity to investigate the whole process of the CME. Filament in this active region rises up rapidly and then hesitates and disintegrates into flare loops. The rising filament from EIT images separates into two parts just before eruption. It is interesting that this filament rises up with positive kink which is opposite to the negative helicity according to the inverse S-shaped X-ray sigmoid and accumulated magnetic helicity. A new filament reforms several hours later after CME and the axis of this new one rotates clockwise about 22° comparing with that of the former one. We also observed a bright transient J-shaped X-ray sigmoid immediately appears after filament eruption. It quickly develops into a soft X-ray cusp and rises up firstly then drops down. We propose that field lines underneath bald-patch sparatrix surface (BPSS) where for the formation of a magnetic tangential discontinuity are locally rooted to the photosphere near the bald-patch (BP) inversion line. Field lines above the surface are detached from the photosphere to form this CME and partially open the field which make the filament loses equilibrium to rise quickly and then be drawn back by the tension force of magnetic field after eruption to form a new filament. Two magnetic cancelation regions have been observed clearly just before filament eruption that reflect the existence of BPs. On the other hand, the values of total magnetic helicity to the corona taken by emergence and differential rotation normalized by the square total magnetic flux implies the possibility of upper bound on the total magnetic helicity that a force-free field can contain.

  10. A comparison of active seismic source data to seismic excitations from the 2012 Tongariro volcanic eruptions, New Zealand

    NASA Astrophysics Data System (ADS)

    Jolly, Arthur; Kennedy, Ben; Keys, Harry; Lokmer, Ivan; Proctor, Jon; Lyons, John; Jolly, Gillian

    2014-05-01

    The 6 August 2012 eruption from Tongariro volcano's Te Maari vent comprised a complex sequence of events including at least 4 eruption jets, a large chasm collapse, and a debris avalanche (volume of ~7x105 m3) that propagated ~2 km beyond the eruptive vent. The eruption was poorly observed, being obscured by night time darkness, and the eruption chronology must be unravelled instead from a complex seismic record that includes discrete volcanic earthquakes, a sequence of low to moderate level spasmodic tremor and an intense burst of seismic and infrasound activity starting at 11:52:18 UTC that marked the eruption onset. We have discriminated the timing of the complex surface activity by comparing active seismic source data to the eruptive sequence. We dropped 11 high impact masses from helicopter to generate a range of active seismic sources in the vicinity of the eruption vent, chasm, and debris avalanche areas. We obtained 8 successful drops having an impact energy ranging from 3 to 9x106 joules producing seismic signals to a distance of 5 to 10 km and having good signal to noise characteristics in the 3-12 Hz range. For the 8 drops, we picked first-P arrival times and calculated amplitude spectra for a uniform set of four 3-component stations. From these, we obtained a distribution of amplitudes across the network for each drop position which varied systematically from the eruption vent and avalanche scar to the debris avalanche toe. We then compared these proxy source excitations to the natural eruption and pre-eruption data using a moving window cross-correlation approach. From the correlation processing, we found evidence for the debris avalanche a few minutes prior to the eruption in both the broad spectrum and narrow frequency (5-10 Hz) analysis. The total seismic energy release calculated from the new method is ~8x1011 joules, similar to an independently estimated calculation based on the radiated seismic energy. The inferred seismic energy release for the

  11. Irreversibility and the Point of No Return in the Evolution of Eruptive Active Regions

    NASA Astrophysics Data System (ADS)

    Georgoulis, Manolis K.

    We combine multiple methods and findings to demonstrate that those eruptive solar active regions that form intense photospheric magnetic polarity inversion lines (PILs) enter a domain of irreversible evolution that will unavoidably force them to erupt at least once, giving rise to a major flare and an associated fast CME. Electric currents, Lorentz forces, free magnetic energy storage, and magnetic helicity, all play major roles in bringing the magnetic configuration on the verge of instability. The inferred irreversibility stems from the conservative properties of magnetic helicity in high magnetic Reynolds-number plasmas. In addition, the long-standing and fiercely debated classification of eruptive magnetic structures into sheared arcades and flux ropes is found to be of relatively little meaning: by means of the evolution above, the simplest possible sheared-arcade structure may gradually evolve into a flux rope susceptible to the helical-kink and the torus instabilities, among other destabilization mechanisms. Research partially supported by the EU Seventh Framework Programme under grant agreement No. PIRG07-GA-2010-268245 and by the European Union Social Fund (ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales. Investing in knowledge society through the European Social Fund.

  12. Phreatomagmatic to Strombolian eruptive activity of basaltic cinder cones: Montaña Los Erales, Tenerife, Canary Islands

    NASA Astrophysics Data System (ADS)

    Clarke, Hilary; Troll, Valentin R.; Carracedo, Juan Carlos

    2009-03-01

    Phreatomagmatic activity results from the interaction of magma and external water during a volcanic eruption and is a frequent eruptive phenomenon worldwide. Such 'fuel-coolant' reactions change the eruptive dynamics, thus generating particles that reflect the degree of explosivity. Different eruptive phases may thus be identified from deposits, allowing us to reconstruct conditions that prevailed in the past and use these to predict the level of explosivity in a given geological setting in the future. A detailed study of the deposits from Montaña Los Erales, a 70 m-high Quaternary cinder cone belonging to a rift-related chain of vents in the Bandas del Sur region, in Southeast Tenerife, was undertaken. Field observations on excavated sections and SEM analysis of tephra suggest that the eruption style changed progressively from an initial phreatomagmatic phase, through a transitional stage, to one that was entirely Strombolian. To investigate the causes and the nature of these changes in eruptive style, products from each major unit were analysed for their morphology using hand specimen observations, secondary electron microscopy, backscatter electron microscopy, and reflected light microscopy to examine fragment size variation, fragment morphologies, vesicularity, and the level of secondary hydrous alteration (e.g. palagonitisation and zeolitisation). Study results demonstrate that the initial phase of activity was largely driven by magma-water interaction, where magma may have interacted with a lens of fresh ground- or surface water. With proceeding eruptive activity the water became exhausted, giving rise to an entirely Strombolian eruptive style. Examples of phreatomagmatic activity that occur on typical rift-related basaltic vent alignments are not infrequent in the Canary Islands. These vent systems usually erupt in Strombolian fashion, producing scoria and lava flows that do not generally extend far beyond the vent area. However, aligned feeders may

  13. A complete solar eruption activity processing tool with robotization and real time (II)

    NASA Astrophysics Data System (ADS)

    Lin, Ganghua; Zhao, Cui; Yang, Xiao

    2014-07-01

    Intense solar active events have made significant impacts on the modern high technology system and living environment of human being, therefore solar activities forecast and space weather forecast are getting more and more attention. Meanwhile, data volume acquisitioned by solar monitor facility is growing larger and larger due to the requirement of multiple dimensions observation and high temporal and spatial resolution. As staffs of a solar monitor data producer, we are encouraged to adopt new techniques and methods to provide valuable information to solar activities forecast organization and the other related users, and provide convenient products and tools to the users. In the previous paper "A complete solar eruption activities processing tool with robotization and real time (I)", we presented a fully automatic and real time detecting architecture for different solar erupt activities. In this paper, we present new components of new data sets in the architecture design, latest progresses on automatic recognition of solar flare, filament and magnetic field, and a newly introduced method with which solar photospheric magnetic nonpotentiality parameters are processed in real time, then its result directly can be used in solar active forecast.

  14. New insights into eruptive activity and lava flow hazard at Nyamulagira volcano, D.R.C., from a new GIS-based lava flow map

    NASA Astrophysics Data System (ADS)

    Smets, B.; Kervyn, M.; Kervyn, F.; D'Oreye, N.; Wauthier, C.

    2010-12-01

    Nyamulagira, located in the western branch of the East African Rift (EAR), is Africa’s most active volcano with one eruption every 2 - 4 years. A map of Nyamulagira lava flows was produced during the 1960’s by Thonnard et al. (1965). This map, which results from the mosaicking of several aerial photographs, contains locally some geographic inaccuracies. The photo-interpretation also led in places to the discrimination of lava units not corresponding to any flow boundaries in the field. Finally, 19 eruptions occurred since this first edition, which causes it to be outdated and of limited use to document the recent eruptive history. Recently, Smets et al. (2010) have produced a new map of lava flows using a combination of optical and radar satellite imagery. This map is GIS-based and can be quickly updated during/after each eruption. Using the new lava flow map of Nyamulagira and a compilation of bibliographic/field information of the last 31 eruptions, the evolution of eruptive activity since the early 1900’s was reconstructed and the volume of erupted lava estimated for each eruption from 1938 to 2010. The spatio-temporal evolution of eruptive activity suggests a strong control from the rift tectonics but also from inherited basement structures on the location, the fissure orientation and the relative lava volume for the successive eruptions. The time lapse after each eruption is strongly correlated with the erupted volume of lava. The 1938-40 eruption is a key event in the volcano recent history, as the corresponding caldera collapse led to an increase of flank eruptions. Nyamulagira flank eruptions systematically destroy large areas of the protected forest of the Virunga National Park, a UNESCO World Heritage in danger since 1994. The lava flows from distal eruptions or from exceptionally high effusion rate or volume events also threaten local population, mainly south of the main edifice near Lake Kivu.

  15. Active seismic sources as a proxy for seismic surface processes: An example from the 2012 Tongariro volcanic eruptions, New Zealand

    NASA Astrophysics Data System (ADS)

    Jolly, A. D.; Lokmer, I.; Kennedy, B.; Keys, H. J. R.; Proctor, J.; Lyons, J. J.; Jolly, G. E.

    2014-10-01

    The 6 August 2012 eruption from Tongariro volcano's Te Maari vent comprised a complex sequence of events including at least 4 eruption pulses, a large chasm collapse, and a debris avalanche (volume of ~ 7 × 105 m3) that propagated ~ 2 km beyond the eruptive vent. The eruption was poorly observed, being obscured by night time darkness, and the eruption timing must be unravelled instead from a complex seismic record that includes discrete volcanic earthquakes, a sequence of low to moderate level spasmodic tremor and an intense burst of seismic and infrasound activity that marked the eruption onset. We have discriminated the evolution of the complex surface activity by comparing active seismic source data to the seismic sequence in a new cross correlation source location approach. We dropped 11 high impact masses from helicopter to generate a range of active seismic sources in the vicinity of the eruption vent, chasm, and debris avalanche areas. We obtained 8 successful drops having an impact energy ranging from 3 to 9 × 106 Nm producing observable seismic signals to a distance of 5 to 10 km and having good signal to noise characteristics in the 3-12 Hz range. For the 8 drops, we picked first-P arrival times and calculated amplitude spectra for a uniform set of four stations. We then compared these proxy source excitations to the natural eruption and pre-eruption data using a moving window cross correlation approach. From the correlation processing, we obtain a best matched source position in the near vent region for the eruption period and significant down channel excitations during both the pre and post eruption periods. The total seismic energy release calculated from the new method is ~ 8 × 1011 Nm, similar to an independently estimated calculation based on the radiated seismic energy. The new energy estimate may be more robust than those calculated from standard seismic radiation equations, which may include uncertainties about the path and site effects. The

  16. Popocatepetl Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Popocatepetl Volcano, almost 30 miles south of Mexico City, erupted yesterday (December 18, 2000) in what authorities are calling its most spectacular eruption since 800 A.D. This morning, Popocatepetl (pronounced poh-poh-kah-TEH-peh-til) continued spewing red-hot rocks as well as a column of smoke and ash about 2.5 miles high into the atmosphere. This true-color image of the volcano was acquired today by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) flying aboard the OrbView-2 satellite. In this image, Popocatepetl's plume (greyish pixels) can be seen blowing southward, away from Mexico City. There is a large cloud bank (bright white pixels) just to the east of the volcanic plume. Although Popocatepetl has been active since 1994-when it awoke from a 70-year slumber-this most recent eruption is most concerning to the greater Mexico City region's 20 million residents. The volcano demonstrated what it can do in 800 A.D. when it belched forth enough lava to fill many of the valleys in the surrounding region. Earlier, scientists warned the citizens of Mexico that there is a dome of lava at the base of the volcano that is causing pressure to build inside. They are concerned that, if it continues to build unabated, this pressure could cause even larger eruptions in the future. Image provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  17. Eyjafjallajökull2010 - The activity of the eruption plume during the first 2 weeks

    NASA Astrophysics Data System (ADS)

    Sigurősson, Árni; Pálmason, Bolli; Hlíőar Jensen, Esther; Petersen, Gudrun Nina; Björnsson, Halldór; Şorsteinsson, Hróbjartur; Arason, Şórőur

    2010-05-01

    On 14 April 2010 an eruption started in Eyjafjallajökull, in southern Iceland. This was an explosive eruption in the caldera, beneath the glacier. During the first two weeks the eruption went through two phases, an explosive phase with much tephra and ash production and a calmer phase with less productivity and some lava production. During the explosive phase 14-17 April, the plume altititude was about 5-7 km but occasionally increased up to 8 km height, there was lightning activity in the plume and the material produced was mainly ash and tephra. It is estimated that the production was peaked at about 750 tons/s. The local ash fall on 17 April was the worst by far for the local community to the south of the volcano as about a 1 km thick ash cloud flowed almost continuously from the volcano and over the region. During this phase the upper level winds over Iceland were strong, northwesterly 40-50 m/s, and the emitted ash was advected southeastward toward northwestern Europe. This caused major disruption in air traffic. During the second phase 18-29 April there was a reduced net output form the volcano, lava production was estimated as 10-30 tons/s and tephra and ash production of less than 10 tons/s. The height of the plume was estimated as 3-5 km. Local ash fall predictions were made for the areas within a 500 km radius from the eruption site and prediction maps published on the website of the Icelandic Met Office. Information on local ash fall were collected from synoptic weather stations but also from the general public and the media. An internet web registration form was made public and advertised. In 6 days 95 reports of ash fall were made. This information together with other ground observations and remote sense observations are important for validations of ash fall prediction, near field and far field, as well as ensuring that the impact of the volcanic eruption is well understood, in a geological, geophysical and biological sense but also the societal

  18. Forecasts and predictions of eruptive activity at Mount St. Helens, USA: 1975-1984

    USGS Publications Warehouse

    Swanson, D.A.; Casadevall, T.J.; Dzurisin, D.; Holcomb, R.T.; Newhall, C.G.; Malone, S.D.; Weaver, C.S.

    1985-01-01

    Public statements about volcanic activity at Mount St. Helens include factual statements, forecasts, and predictions. A factual statement describes current conditions but does not anticipate future events. A forecast is a comparatively imprecise statement of the time, place, and nature of expected activity. A prediction is a comparatively precise statement of the time, place, and ideally, the nature and size of impending activity. A prediction usually covers a shorter time period than a forecast and is generally based dominantly on interpretations and measurements of ongoing processes and secondarily on a projection of past history. The three types of statements grade from one to another, and distinctions are sometimes arbitrary. Forecasts and predictions at Mount St. Helens became increasingly precise from 1975 to 1982. Stratigraphic studies led to a long-range forecast in 1975 of renewed eruptive activity at Mount St. Helens, possibly before the end of the century. On the basis of seismic, geodetic and geologic data, general forecasts for a landslide and eruption were issued in April 1980, before the catastrophic blast and landslide on 18 May 1980. All extrusions except two from June 1980 to the end of 1984 were predicted on the basis of integrated geophysical, geochemical, and geologic monitoring. The two extrusions that were not predicted were preceded by explosions that removed a substantial part of the dome, reducing confining pressure and essentially short-circuiting the normal precursors. ?? 1985.

  19. Community Analysis of Dynamic Microbial Mat Communities from Actively Erupting Seamounts (Invited)

    NASA Astrophysics Data System (ADS)

    Davis, R.; Tebo, B.; Moyer, C. L.

    2009-12-01

    The actively erupting deep-sea volcanoes NW Rota-1 and W Mata have multiple diffuse low-temperature (Tmax= 20-30 degrees) vent sites which harbor dense populations of microbial mat communities driven by chemoautotrophy. These microbial mats were often composed of white filamentous bacteria growing in close proximity to focused hydrothermal flow. Eight microbial mats were sampled from discrete hydrothermal vents on NW Rota-1 and W Mata volcanoes in 2009. The microbial mat communities were analyzed with quantitative PCR (Q-PCR) and terminal-restriction fragment length polymorphism (T-RFLP) community fingerprinting. All of the sampled microbial mats were dominated by the class Epsilonproteobacteria. The microbial mat at Iceberg Vent contained 13.5% Archaea, while all other microbial mats contained less than 1% Archaea. Bacterial community fingerprints from NW Rota-1 and W Mata formed distinct clusters that were well separated from clusters formed by hydrothermal communities from Axial and Eifuku Seamounts that were also dominated by Epsilonproteobacteria. Iceberg vent communities from NW Rota-1 have transitioned from being dominated by Caminibacter phylotypes to Sulfuimonas group phylotypes since 2004. These data suggest that microbial communities found on actively erupting volcanoes are geographically distinct and provide a natural laboratory to study microbial colonization and community succession at hydrothermal systems.

  20. Data-driven magnetohydrodynamic modelling of a flux-emerging active region leading to solar eruption

    PubMed Central

    Jiang, Chaowei; Wu, S. T.; Feng, Xuesheng; Hu, Qiang

    2016-01-01

    Solar eruptions are well-recognized as major drivers of space weather but what causes them remains an open question. Here we show how an eruption is initiated in a non-potential magnetic flux-emerging region using magnetohydrodynamic modelling driven directly by solar magnetograms. Our model simulates the coronal magnetic field following a long-duration quasi-static evolution to its fast eruption. The field morphology resembles a set of extreme ultraviolet images for the whole process. Study of the magnetic field suggests that in this event, the key transition from the pre-eruptive to eruptive state is due to the establishment of a positive feedback between the upward expansion of internal stressed magnetic arcades of new emergence and an external magnetic reconnection which triggers the eruption. Such a nearly realistic simulation of a solar eruption from origin to onset can provide important insight into its cause, and also has the potential for improving space weather modelling. PMID:27181846

  1. Data-driven magnetohydrodynamic modelling of a flux-emerging active region leading to solar eruption.

    PubMed

    Jiang, Chaowei; Wu, S T; Feng, Xuesheng; Hu, Qiang

    2016-01-01

    Solar eruptions are well-recognized as major drivers of space weather but what causes them remains an open question. Here we show how an eruption is initiated in a non-potential magnetic flux-emerging region using magnetohydrodynamic modelling driven directly by solar magnetograms. Our model simulates the coronal magnetic field following a long-duration quasi-static evolution to its fast eruption. The field morphology resembles a set of extreme ultraviolet images for the whole process. Study of the magnetic field suggests that in this event, the key transition from the pre-eruptive to eruptive state is due to the establishment of a positive feedback between the upward expansion of internal stressed magnetic arcades of new emergence and an external magnetic reconnection which triggers the eruption. Such a nearly realistic simulation of a solar eruption from origin to onset can provide important insight into its cause, and also has the potential for improving space weather modelling. PMID:27181846

  2. Data-driven magnetohydrodynamic modelling of a flux-emerging active region leading to solar eruption

    NASA Astrophysics Data System (ADS)

    Jiang, Chaowei; Wu, S. T.; Feng, Xuesheng; Hu, Qiang

    2016-05-01

    Solar eruptions are well-recognized as major drivers of space weather but what causes them remains an open question. Here we show how an eruption is initiated in a non-potential magnetic flux-emerging region using magnetohydrodynamic modelling driven directly by solar magnetograms. Our model simulates the coronal magnetic field following a long-duration quasi-static evolution to its fast eruption. The field morphology resembles a set of extreme ultraviolet images for the whole process. Study of the magnetic field suggests that in this event, the key transition from the pre-eruptive to eruptive state is due to the establishment of a positive feedback between the upward expansion of internal stressed magnetic arcades of new emergence and an external magnetic reconnection which triggers the eruption. Such a nearly realistic simulation of a solar eruption from origin to onset can provide important insight into its cause, and also has the potential for improving space weather modelling.

  3. 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

  4. Volcanic and seismic activity at Stromboli preceding the 2002-2003 flank eruption

    NASA Astrophysics Data System (ADS)

    Burton, M.; Calvari, S.; Spampinato, L.; Lodato, L.; Pino, N. A.; Marchetti, E.; Murè, F.

    Regular surveys with a thermal camera from both ground- and helicopter-based surveys have been carried out on Stromboli since October 2001. This data set allowed us to detect morphological changes in Stromboli's summit craters produced by major explosions and to track an increase in volcanic activity associated with a heightened magma level within the main conduit that preceded the 2002-2003 effusive eruption. Together with thermal measurements, geophysical surveys performed in May and September/October 2002 highlighted clear increases in the amplitude of very long period (VLP) events, consistent with the ascent of the magma column above the VLP source region. The increased magma level was probably induced by elevated pressure in the deep feeding system, controlled by regional tectonic stress. This, in turn, pressurized the uppermost part of the crater terrace, producing greater soil permeability and soil degassing. Eventually, the magma loading caused the NW flank of the summit craters to fracture, allowing lava to flood out at high effusion rates on 28 December 2002, starting an approximately 6-month-long effusive eruption.

  5. 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

  6. 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.

  7. 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

  8. Volcanology and eruptive styles of Barren Island: an active mafic stratovolcano in the Andaman Sea, NE Indian Ocean

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Ray, Jyotiranjan S.; Bhutani, Rajneesh; Kumar, Alok; Smitha, R. S.

    2009-11-01

    Barren Island (India) is a relatively little studied, little known active volcano in the Andaman Sea, and the northernmost active volcano of the great Indonesian arc. The volcano is built of prehistoric (possibly late Pleistocene) lava flows (dominantly basalt and basaltic andesite, with minor andesite) intercalated with volcaniclastic deposits (tuff breccias, and ash beds deposited by pyroclastic falls and surges), which are exposed along a roughly circular caldera wall. There are indications of a complete phreatomagmatic tephra ring around the exposed base of the volcano. A polygenetic cinder cone has existed at the centre of the caldera and produced basalt-basaltic andesite aa and blocky aa lava flows, as well as tephra, during historic eruptions (1787-1832) and three recent eruptions (1991, 1994-95, 2005-06). The recent aa flows include a toothpaste aa flow, with tilted and overturned crustal slabs carried atop an aa core, as well as locally developed tumuli-like elliptical uplifts having corrugated crusts. Based on various evidence we infer that it belongs to either the 1991 or the 1994-95 eruptions. The volcano has recently (2008) begun yet another eruption, so far only of tephra. We make significantly different interpretations of several features of the volcano than previous workers. This study of the volcanology and eruptive styles of the Barren Island volcano lays the ground for detailed geochemical-isotopic and petrogenetic work, and provides clues to what the volcano can be expected to do in the future.

  9. Exploring a long-lasting volcanic eruption by means of in-soil radon measurements and seismic activity

    NASA Astrophysics Data System (ADS)

    Falsaperla, Susanna; Neri, Marco; Di Grazia, Giuseppe; Langer, Horst; Spampinato, Salvatore

    2016-04-01

    We analyze in-soil radon (Rn) emission and ambient parameters (barometric pressure and air temperature measurements) along with seismic activity during the longest flank eruption of this century at Mt. Etna, Italy. This eruption occurred between 14 May 2008 and 6 July 2009, from a N120-140°E eruptive fissure extending between 3050 and 2620 m above sea level. It was heralded by a short-lived (~5 hours) episode of lava fountaining three days before a dike-forming intrusion fed a lava emission, which affected the summit area of the volcano over ~15 months. The peculiar position of the station for the Rn measurement, which was at an altitude of 2950 m above sea level and near (~1 km) the summit active craters, offered us the uncommon chance: i) to explore the temporal development of the gas emission close (<2 km) to the 2008-2009 eruptive vents in the long term, and ii) to analyze the relationship between in-soil Rn fluxes and seismic signals (in particular, local earthquakes and volcanic tremor) during the uninterrupted lava emission. This approach reveals important details about the recharging phases characterizing the 2008-2009 eruption, which are not visible with other methods of investigation. Our study benefitted from the application of methods of pattern classification developed in the framework of the European MEDiterrranean Supersite Volcanoes (MED­SUV) project.

  10. 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

    , while juvenile component increased. Total ash fallout mass since August 14 yield 1.19E+9 kg. During these episodes BrO and HCl were detected in the plume, and airborne Multi-GAS measurements showed that the plume had a CO2/SO2 ratio from 1 to 2.5 and that SO2 was >99% of total sulfur (SO2+ H2S), indicating a shallow magmatic origin for the gas. During ash emissions temperatures of up to 200° C were measured at the column with an IR camera. Thermal anomalies in the upper part of the edifice have also been observed and have resulted in minor melting of the ice cap. This phenomenon has produced small secondary lahars with a maximum discharge on the order of 10 to 30 m3/s. Since late November 2015, surface manifestations and the other monitored parameters have shown a marked decrease. Historical reports of Cotopaxi's activity show that both short and long-lasting eruptive periods usually start with mild eruptive phases prior to culminating in VEI 3 or 4 eruptions. Therefore special care should be taken in monitoring unrest at Cotopaxi in order to identify precursory signs of a larger eruption.

  11. Large Solar Energetic Particle Events Associated With Filament Eruptions Outside Active Regions

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

    2015-01-01

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds approx. 1000 km/s) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of approx.2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ?4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  12. Large Solar Energetic Particle Events Associated with Filament Eruptions Outside of Active Regions

    NASA Astrophysics Data System (ADS)

    Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

    2015-06-01

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds ˜ 1000 km s-1) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of ˜2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ≥4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  13. Fault activation after vigorous eruption: the December 8, 2015 seismic swarm at Mt. Etna

    NASA Astrophysics Data System (ADS)

    Alparone, Salvatore; Bonforte, Alessandro; Guglielmino, Francesco; Maiolino, Vincenza; Puglisi, Giuseppe; Ursino, Andrea

    2016-04-01

    From December 2, 2015, volcanic activity suddenly occurred on Mt. Etna with very violent fire fountaining at central crater, known also as "Voragine". This activity continued with other intense episodes at the same crater during the three following days and involving also, in turn, all the other three summit craters. This sudden eruption produced a rapid deflation of the volcano and was followed, from December 8, by a seismic swarm, with almost eighty earthquakes during this day, located on the uppermost segment of the Pernicana-Provenzana fault system (PFS). This seismicity was characterized by shallow foci (from few hundred meters until 1.5 km below the sea level) and mainshock with 3.6 magnitude. In order to investigate and measure the dynamics controlling and accompanying the PFS activation, a dataset composed of C-Band Sentinel-1A data has been used for SAR Interferometry (InSAR) analysis. Some interferograms have been generated from ascending and descending orbits in order to analyze both short- and long-term deformation. The availability of GPS data allowed comparing and integrating them with InSAR for ground truth and modeling aims. The surface kinematics and modeling obtained by DInSAR and GPS data and integration have been compared to the distribution of the seismicity and related focal mechanisms in order to define the fault geometry and motion. Moreover, essential constraints have been achieved about the PFS dynamic and its relationship with the intense volcanic activity occurred.

  14. Record of complex scoria cone eruptive activity at Red Mountain, Arizona, USA, and implications for monogenetic mafic volcanoes

    NASA Astrophysics Data System (ADS)

    Riggs, N. R.; Duffield, W. A.

    2008-12-01

    for sealing fine-grained ash beds in the cone, and a pressurized system developed. Residual heat from a dike that was emplaced as part of the magmatic activity provided heat that drove groundwater along the regional fault up into the cone. Eventually the overpressurized system exploded in a phreatic eruption that created the amphitheatre, which has subsequently been enlarged by water and wind erosion. The combined sequence of events at Red Mountain illustrates some of the complexities in monogenetic scoria cone eruptions that have received little attention to date.

  15. 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

  16. Seismic time-frequency analysis of the recent 2015 eruptive activity of Volcán de Colima, Mexico

    NASA Astrophysics Data System (ADS)

    Vargas-Bracamontes, D. M.; Nava Pichardo, F. A.; Reyes Dávila, G. A.; Arámbula-Mendoza, R.; Martínez Fierros, A.; Ramírez Vázquez, A.; González Amezcua, M.

    2015-12-01

    Volcán de Colima is an andesitic stratovolcano located in western Mexico. It is considered the most active volcano in Mexico, with activity characterized mainly by intermittent effusive and explosive episodes. On July 10th-12th 2015, Volcán de Colima underwent its most intense eruptive phase since its Plinian eruption in 1913. A partial collapse of the dome and of the crater wall generated several pyroclastic flows, the largest of which reached almost 10 km to the south of the volcano. Lava flows along with incandescent rockfalls descended through various flanks of the volcanic edifice. Ashfall affected people up to 40 km from the volcano's summit. Inhabitants from the small villages closest to the volcano were evacuated and authorities sealed off a 12 km area. We present an overview of the seismic activity that preceded and accompanied this eruptive phase, with data from the closest broadband and short period seismic stations of the Volcán de Colima monitoring network. We focus on the search of temporal information within the spectral content of the seismic signals. We first employ common time-frequency representations such as Fourier and wavelet transforms, but we also apply more recent techniques proposed for the analysis of non-stationary signals, such as empirical mode decomposition and the synchrosqueezing transform. We present and discuss the performances of these various methods characterizing and quantifying spectral changes which could be used to forecast future eruptive events and to evaluate the course of volcanic processes during ongoing eruptions.

  17. Reconstructing 800 years of historical eruptive activity at Popocatépetl Volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Martin-Del Pozzo, Ana Lillian; Rodríguez, Alan; Portocarrero, Jorge

    2016-03-01

    Pictorial and written documents spanning 800 years were analyzed for information about historical eruptions at Popocatépetl volcano. These documents were prepared by several indigenous groups as well as by the Spanish conquistadors and missionaries during their military campaigns and long-term evangelization and colonization and later on, by Indian nobles and Spanish historians. Pre-Columbian drawings show flames coming out of Popocatépetl's crater while later descriptions from the Spanish colonial period in Mexico (1521 to 1821) refer to ash emission and ballistics, lahars, and some pumice falls, similar to what were depicted in the thirteenth to sixteenth century drawings. Graphic information from the pre-Columbian codices, colonial maps, and paintings referring to the eruptions were correlated with historical accounts and religious chronicles, thereby leading to the reconstruction of a more detailed sequence of eruptive events. From such information, it was possible for us to prepare ash distribution maps for the 1540, 1592, and 1664 eruptions. Most of the known historical eruptions seem to be similar to those that have been occurring at Popocatépetl since 1994, indicating the importance of ash emission and crater dome formation throughout its recent eruptive history. The strongest eruptions occurred in 1510, 1519, 1540, 1580, 1664, and 2001; these produced widespread ash falls that affected both populated and rural areas. Duration of eruptive episodes during the past 800 years were estimated to have ranged from less than a year to more than 30 years, separated by repose periods ranging between 7 and over 100 years.

  18. 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

  19. 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

  20. 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

  1. 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

  2. Trigger Mechanisms for Volcanic Eruptions at Campi Flegrei caldera (Southern-Italy) in the last 5ka of activity

    NASA Astrophysics Data System (ADS)

    Arienzo, I.; D'Antonio, M.; Moretti, R.; Cavallo, A.; Civetta, L.; Orsi, G.

    2012-12-01

    Products from the 3.98 ± 0.53 ka year-old Nisida eruption have been studied in order to investigate the role of magma mingling/mixing, degassing and crystal fractionation in triggering volcanic eruptions during the last 5 ka of volcanic activity at Campi Flegrei caldera (Southern Italy). Due to persistent unrest, the explosive character of its volcanism and the large population living within the caldera and its surroundings, the volcanic risk in this nested, resurgent caldera is among the highest on Earth and demands an accurate reconstruction of processes driving recent volcanism. We present major elements and isotope data on bulk rock, glass matrix and separated phenocrysts, along with major and volatile elements on clinopyroxene-hosted melt inclusions, of products from Nisida and other Campi Flegrei eruptions occurred in the last 5 ka. The new data, together with literature data, suggest that crystal fractionation may account for the chemical variability of the extruded melt, although additional processes, such as magma mingling/mixing and/or entrapment of antecrysts into the magma prior to eruption are required to explain the large isotopic variation displayed by the analyzed products. In particular, the Nisida eruption was triggered by the arrival of isotopically distinct (87Sr/86Sr ~ 0.7073), poorly differentiated (latite), volatile-rich magma (H2O up to 4 wt.%). This is in line with what already proposed for the Agnano-Monte Spina (~ 4.1 ka) and Minopoli 2 eruptions (~ 9.7 ka), both occurred in the eastern sector of the Campi Flegrei caldera affected by extension. Noteworthy, Campi Flegrei caldera is located at the intersection of regional NE-SW and NW-SE fault systems and characterized by large caldera-forming eruptions and resurgence of the caldera floor following a simple shearing mechanism. In particular, deep, latitic magmas, rose along portions of faults of the NE-SW system, in the eastern sector of the caldera affected by extensional processes

  3. Triple Solar Eruption

    NASA Video Gallery

    Solar activity surged on the morning of Dec 12, 2010 when the sun erupted three times in quick succession, hurling a trio of bright coronal mass ejections (CMEs) into space. Coronagraphs onboard th...

  4. The ongoing Puʻu ʻŌʻō eruption of Kīlauea Volcano, Hawaiʻi: 30 years of eruptive activity

    USGS Publications Warehouse

    Orr, Tim R.; Heliker, Christina; Patrick, Matthew R.

    2013-01-01

    The Puʻu ʻŌʻō eruption of Kīlauea Volcano is its longest rift-zone eruption in more than 500 years. Since the eruption began in 1983, lava flows have buried 48 square miles (125 square kilometers) of land and added about 500 acres (200 hectares) of new land to the Island of Hawaiʻi. The eruption not only challenges local communities, which must adapt to an ever-changing and sometimes-destructive environment, but has also drawn millions of visitors to Hawaiʻi Volcanoes National Park. U.S. Geological Survey (USGS) scientists closely monitor and evaluate hazards at Hawaiʻi’s volcanoes and also work with park rangers to help ensure safe lava viewing for visitors.

  5. Transition from Effusive to Explosive Activity during Lava Dome Eruption: The Example of the 2010 of Merapi Volcano (Java, Indonesia)

    NASA Astrophysics Data System (ADS)

    Drignon, M. J.; Arbaret, L.; Burgisser, A.; Komorowski, J. C.; Martel, C.; Putra, R.

    2014-12-01

    Understanding the transition between effusive and explosive activity in dome-forming volcanoes remains a challenging question for eruption forecasting and eruptive scenario definition. The explosive activity of 26 Oct. and 5 Nov. during the 2010 eruption of Merapi volcano offers the opportunity to explore this transition by quantifying the mechanisms that led to the dome explosion. Forty-three pumice samples were analyzed by 1) scanning electron microscope for textural analysis and 2) elemental analyzer for water content. The SEM images were processed so as to determine the proportions of gas bubbles, microlites and glass in each sample. These data were combined with the glass water content to feed the simple physical model developed by Burgisser et al. [1,2] to calculate pre-explosive pressure, depth, and porosity level for each pyroclastic pumice sample. Preliminary results indicate that the water content in the melt is high, reaching 7 wt.%. These water contents yield a wide range of pre-eruptive pressures. Samples from 26 Oct. originated at pressures from a few MPa to 280 MPa. These pressures correspond to depths ranging from a few hundred meters to more than 10 km. This suggests that large overpressures were associated with conduit evacuation that reached unexpected depths. Samples from the 5 Nov. event range from ~10 to ~100 MPa. This suggests that this event also evacuated a large part of the volcanic conduit. Pre-explosive porosities of both events are low (<10 vol. %) along the depth of the entire conduit, which suggests extensive permeable outgassing of the magma-filed conduit prior to each explosive evacuation. Ongoing work includes analysis of melt CO2 content due to preliminary evidence that it played an important role in the 2010 Merapi eruption. The modeled conduit properties serve as baseline data for conduit flow modeling and building plausible eruptive scenarios. [1] Burgisser et al. (2010) J. Volcanol. Geotherm. Res. 194, 27-41. [2] Burgisser et

  6. 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.

  7. The transition from summit to flank activity at Mt. Etna, Sicily (Italy): Inferences from the petrology of products erupted in 2007-2009

    NASA Astrophysics Data System (ADS)

    Corsaro, Rosa Anna; Miraglia, Lucia

    2014-04-01

    Mt. Etna is an active basaltic volcano where both flank and summit eruptions take place. In recent decades, the South-East summit crater (SEC) has in particular been characterized by 'episodic' eruptions, consisting of recurrent lava fountains associated with lava flow emissions and lasting from a few weeks to months. Recent volcanic activity shows that, if there is a transition from an episodic summit eruption to a flank eruption, then this usually takes place while the last paroxysm of the episodic eruption is still underway. By contrast, the 2007-08 episodic eruption at SEC was followed by the 2008-09 flank activity which started three days after the conclusion of the last paroxysm, coinciding with the strong earthquake (M = 7.9) in Sichuan (China), whose perturbations were recorded by the monitoring network of Mt. Etna. We therefore investigated the transition from a summit episodic eruption at SEC to flank activity utilizing a petrologic study of the products erupted from 2007 to 2009, integrated with literature data. The compositional variability of the products may largely be explained by a mixing between an evolved magma stored in the SEC reservoir and a more primitive magma which intrudes it. In the studied period, the most significant episodes of magma recharge occurred before the onset of the 2007-08 episodic eruption and during the 2008-09 flank activity, more precisely before June 2008. According to previous studies, the seven paroxysms of the 2007-08 episodic eruption at SEC have been interpreted as resulting from the disruption of a foam layer at the top of the SEC reservoir which was rebuilt before each subsequent episode. The transition from the 2007-08 episodic eruption at SEC to the 2008-09 flank activity was essentially triggered by the Sichuan earthquake which caused a variation of dynamic stress. It caused the volatile exolution, the pressurization of SEC stored magma, and the consequent fracturing of the surrounding rocks where magma intruded

  8. The transition summit-flank activity at Mt. Etna, Sicily (Italy): inferences from the petrology of products erupted from 2007 to 2009

    NASA Astrophysics Data System (ADS)

    Corsaro, Rosa Anna; Miraglia, Lucia

    2014-05-01

    Mt. Etna is an active basaltic volcano where both flank and summit eruptions take place. In particular, the South-East summit crater (SEC) during the last decades has been characterized by 'episodic' eruptions, which consist of recurrent lava fountains associated with lava flows emission, lasting from a few weeks to months. The past recent volcanic activity has shown that, if a transition from an episodic summit eruption to a flank eruption occurred, it generally took place while the last paroxysm of the episodic eruption was still underway. Differently, the 2007-08 episodic eruption at SEC was followed by the 2008-09 flank activity which started three days after the conclusion of the last paroxysm, in coincidence with the strong earthquake (M= 7.9) in Sichuan (China), whose perturbations have been registered by the monitoring network of Mt. Etna. We then investigated the transition from summit episodic activity at SEC to flank eruption utilizing a petrologic study of the products erupted from 2007 to 2009 integrated with data from the literature. The compositional variability of the products is mainly explainable with a mixing between an evolved magma stored in the SEC reservoir and a more primitive magma which intrudes it. In the studied period the most significant episodes of magma recharge occurred before the onset of the 2007-08 episodic activity and during the 2008-09 flank eruption, more precisely before June 2008. According to previous studies the seven episodes of the 2007-08 eruption at SEC have been interpreted to result from the disruption of a foam layer at the top of the SEC reservoir which was rebuilt before each subsequent episode. The transition from 2007-08 episodic eruption at SEC to the 2008-09 flank activity was essentially triggered by the Sichuan earthquake which caused a variation of dynamic stress. It promoted the volatile exolution, the pressurization of SEC stored magma, and the consequent fracturing of the surrounding rocks where magma

  9. MICRO-SIGMOIDS AS PROGENITORS OF CORONAL JETS: IS ERUPTIVE ACTIVITY SELF-SIMILARLY MULTI-SCALED?

    SciTech Connect

    Raouafi, N.-E.; Rust, D. M.; Bernasconi, P. N.; Georgoulis, M. K.

    2010-08-01

    Observations from the X-ray telescope (XRT) on Hinode are used to study the nature of X-ray-bright points, sources of coronal jets. Several jet events in the coronal holes are found to erupt from small-scale, S-shaped bright regions. This finding suggests that coronal micro-sigmoids may well be progenitors of coronal jets. Moreover, the presence of these structures may explain numerous observed characteristics of jets such as helical structures, apparent transverse motions, and shapes. Analogous to large-scale sigmoids giving rise to coronal mass ejections (CMEs), a promising future task would perhaps be to investigate whether solar eruptive activity, from coronal jets to CMEs, is self-similar in terms of properties and instability mechanisms.

  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. Isotopic and ion analysis of erupting Lusi water for constraints on numerical models

    NASA Astrophysics Data System (ADS)

    Faubert, Maïté; Sohrabi, Reza; Mauri, Guillaume; Mazzini, Adriano; Miller, Stephen

    2016-04-01

    The LUSI mud eruption, in the Sidoarjo district, East Java, Indonesia, has been continuously erupting great amounts of material for ten years. From a hydrogeological point of view, the hypothesis that this is a newly born deep hydrothermal system is supported by geochemistry, thermal properties, and its geyser-like behavior. The present work investigates the configuration of this hydrogeological system through hydro-chemical analysis of the erupting fluids, and to establish constraints on numerical model parameters. We used two different radioactive isotope dating methods (δ14C and δ3H) to constrain travel time from inflow to outflow, and major ion analyses to determine water-type from LUSI. We also measured δ2H and δ18O to determine the source of the water. Additionally, it has been reported that significant amounts of Li is found in the erupting fluid. Result of δ14C provides ages in the range of 16ka, and ion analyses show the water is of the Na-Cl type, typical for hydrothermal volcanic fluids. However, typical volcanic fluids have high K, and the low K that we measured in the LUSI erupting waters could result from K-consumption associated with smectite-illite metamorphism (e.g. dehydration) of the Upper Kalibeng formation. The quantity of Li reinforces the volcanic source hypothesis, while the stable isotope results show that the water feeding the erupting system is a combination of formation dehydration, magmatic origin, and mixed with some meteoric water. We propose that the erupting water originates from deep strata, likely below the carbonate formation at a depth of > 4 km deep. The carbonate formation provides the necessary permeability to feed the substantial outflow observed at the surface. The Arjuno-Welirang volcanic complex, situated at ~20 km from LUSI, offers the necessary hydraulic gradient to drive the eruption. These parameters provide constraints on numerical models that we are developing to understand LUSI's deep hydrodynamic

  12. The link between multistep magma ascent and eruption intensity: examples from the recent activity of Piton de la Fournaise (La Réunion Island).

    NASA Astrophysics Data System (ADS)

    Di Muro, Andrea

    2014-05-01

    Caldera collapses represent catastrophic events, which induce drastic modification in a volcano plumbing system and can result in major and fast evolution of the system dynamics. At Piton de la Fournaise (PdF) volcano, the 2007 eruptive sequence extruded the largest lava volume (240 Mm3) since at least 3 centuries, provoking the collapse of a small (1 km wide; 340 m deep) summit caldera. In about 35 days, the 2007 major eruption generated i) the greatest lava output rate, ii) the strongest lava fountaining activity (> 200 m high), iii) the largest SO2 volume (> 230 kt) ever documented at PdF. This event ended a 9 year-long period (1998-2007) of continuous edifice inflation and sustained eruptive activity (3 eruptions per year on average). Unexpectedly and in spite of the large volume of magma erupted in 2007, volcano unrest and eruptive activity resumed quickly in 2008, soon after caldera collapse, and produced several closely spaced intracaldera eruptions and shallow intrusions. The post-2007 activity is associated with a trend of continuous volcano deflation and consists in small-volume (<3 Mm3) weak (< 20 m high fountains; strombolian activity) summit/proximal eruptions of moderate/low MgO magmas and frequent shallow magma intrusions. Non-eruptive tremor and increase in SO2 emissions were interpreted as evidences of magma intrusions at shallow depth (< 2.0 km) preceding the eruptions. The 2007-2011 phase of activity represents an ideal case-study to analyze the influence of magma ascent kinetics on the evolution of volcano dynamics at a persistently active basaltic volcano. In order to track magma storage and ascent, we compare geochemical data on fast quenched glasses (melt inclusions, Pele's hairs, coarse ash fragments produced by lava-sea water interaction, glassy crust of lavas, high-temperature lavas quenched in water, matrix glasses) with the geophysical record of volcano unrest. Petro-chemical data suggest that the shallow PdF plumbing system is formed by

  13. Pre-flare Activity and Magnetic Reconnection during the Evolutionary Stages of Energy Release in a Solar Eruptive Flare

    NASA Astrophysics Data System (ADS)

    Joshi, Bhuwan; Veronig, Astrid M.; Lee, Jeongwoo; Bong, Su-Chan; Tiwari, Sanjiv Kumar; Cho, Kyung-Suk

    2011-12-01

    In this paper, we present a multi-wavelength analysis of an eruptive white-light M3.2 flare that occurred in active region NOAA 10486 on 2003 November 1. The excellent set of high-resolution observations made by RHESSI and the TRACE provides clear evidence of significant pre-flare activities for ~9 minutes in the form of an initiation phase observed at EUV/UV wavelengths followed by an X-ray precursor phase. During the initiation phase, we observed localized brightenings in the highly sheared core region close to the filament and interactions among short EUV loops overlying the filament, which led to the opening of magnetic field lines. The X-ray precursor phase is manifested in RHESSI measurements below ~30 keV and coincided with the beginning of flux emergence at the flaring location along with early signatures of the eruption. The RHESSI observations reveal that both plasma heating and electron acceleration occurred during the precursor phase. The main flare is consistent with the standard flare model. However, after the impulsive phase, an intense hard X-ray (HXR) looptop source was observed without significant footpoint emission. More intriguingly, for a brief period, the looptop source exhibited strong HXR emission with energies up to ~50-100 keV and significant non-thermal characteristics. The present study indicates a causal relation between the activities in the pre-flare and the main flare. We also conclude that pre-flare activities, occurring in the form of subtle magnetic reorganization along with localized magnetic reconnection, played a crucial role in destabilizing the active region filament, leading to a solar eruptive flare and associated large-scale phenomena.

  14. Multistation alarm system for eruptive activity based on the automatic classification of volcanic tremor: specifications and performance

    NASA Astrophysics Data System (ADS)

    Langer, Horst; Falsaperla, Susanna; Messina, Alfio; Spampinato, Salvatore

    2015-04-01

    With over fifty eruptive episodes (Strombolian activity, lava fountains, and lava flows) between 2006 and 2013, Mt Etna, Italy, underscored its role as the most active volcano in Europe. Seven paroxysmal lava fountains at the South East Crater occurred in 2007-2008 and 46 at the New South East Crater between 2011 and 2013. Month-lasting lava emissions affected the upper eastern flank of the volcano in 2006 and 2008-2009. On this background, effective monitoring and forecast of volcanic phenomena are a first order issue for their potential socio-economic impact in a densely populated region like the town of Catania and its surroundings. For example, explosive activity has often formed thick ash clouds with widespread tephra fall able to disrupt the air traffic, as well as to cause severe problems at infrastructures, such as highways and roads. For timely information on changes in the state of the volcano and possible onset of dangerous eruptive phenomena, the analysis of the continuous background seismic signal, the so-called volcanic tremor, turned out of paramount importance. Changes in the state of the volcano as well as in its eruptive style are usually concurrent with variations of the spectral characteristics (amplitude and frequency content) of tremor. The huge amount of digital data continuously acquired by INGV's broadband seismic stations every day makes a manual analysis difficult, and techniques of automatic classification of the tremor signal are therefore applied. The application of unsupervised classification techniques to the tremor data revealed significant changes well before the onset of the eruptive episodes. This evidence led to the development of specific software packages related to real-time processing of the tremor data. The operational characteristics of these tools - fail-safe, robustness with respect to noise and data outages, as well as computational efficiency - allowed the identification of criteria for automatic alarm flagging. The

  15. Localization of volcanic activity: Topographic effects on dike propagation, eruption and conduit formation

    NASA Astrophysics Data System (ADS)

    Gaffney, Edward S.; Damjanac, Branko

    2006-07-01

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

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

    SciTech Connect

    E.S. Gaffney; B. Damjanac

    2006-05-12

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

  17. Evidence of flux rope and sigmoid in Active Regions prior eruptions

    NASA Astrophysics Data System (ADS)

    Schmieder, Brigitte; Aulanier, Guillaume; Janvier, Miho; Bommier, Veronique; Dudik, Jaroslav; Gilchrist, Stuart; Zhao, Jie

    2016-07-01

    In the solar corona, the magnetic field is dominant, and the current density vector is nearly aligned with the magnetic field lines for strong and stressed field regions. Stressed and highly twisted flux ropes are at the origin of eruptive events such as flares and coronal mass ejections, which inject material into the interplanetary medium. The standard three dimensional (3D) flare model predicts the complex evolution of flare loops and the flux rope before the eruption. Flux ropes are not directly observed in the corona, however it has started to be possible to detect their footprints in the photosphere. Recent high spatial and temporal resolution spectro-polarimeters have allowed us to compute the photospheric electric currents and follow their evolution. Characteristics pattern like J-shaped ribbons indicate the presence of a flux rope before the flare. The results confirm the predictions of the 3D MHD standard model of eruptive flares. It is interesting to compare the magnetic helicity of the ejected flux rope with the in situ measurements of the corresponding ICME at L1. We will show some examples (February 15 2011, July 12 2012, Sept 10 2014).

  18. Products of Submarine Fountains and Bubble-burst Eruptive Activity at 1200 m on West Mata Volcano, Lau Basin

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Rubin, K. H.; Keller, N. S.

    2009-12-01

    An eruption was observed and sampled at West Mata Volcano using ROV JASON II for 5 days in May 2009 during the NSF-NOAA eruption response cruise to this region of suspected volcanic activity. Activity was focused near the summit at the Prometheus and Hades vents. Prometheus erupted almost exclusively as low-level fountains. Activity at Hades cycled between vigorous degassing, low fountains, and bubble-bursts, building up and partially collapsing a small spatter/scoria cone and feeding short sheet-like and pillow flows. Fire fountains at Prometheus produced mostly small primary pyroclasts that include Pele's hair and fluidal fragments of highly vesicular volcanic glass. These fragments have mostly shattered and broken surfaces, although smooth spatter-like surfaces also occur. As activity wanes, glow in the vent fades, and denser, sometimes altered volcanic clasts are incorporated into the eruption. The latter are likely from the conduit walls and/or vent-rim ejecta, drawn back into the vent by inrushing seawater that replaces water entrained in the rising volcanic plume. Repeated recycling of previously erupted materials eventually produces rounded clasts resembling beach cobbles and pitted surfaces on broken phenocrysts of pyroxene and olivine. We estimate that roughly 33% of near vent ejecta are recycled. Our best sample of this ejecta type was deposited in the drawer of the JASON II ROV during a particularly large explosion that occurred during plume sampling immediately above the vent. Elemental sulfur spherules up to 5 mm in diameter are common in ejecta from both vents and occur inside some of the lava fragments Hades activity included dramatic bubble-bursts unlike anything previously observed under water. The lava bubbles, sometimes occurring in rapid-fire sequence, collapsed in the water-column, producing fragments that are quenched in less than a second to form Pele's hair, limu o Pele, spatter-like lava blobs, and scoria. All are highly vesicular

  19. Fossil and active fumaroles in the 1912 eruptive deposits, Valley of ten thousand smokes, Alaska

    USGS Publications Warehouse

    Keith, T.E.C.

    1991-01-01

    Fumaroles in the ash-flow sheet emplaced during the 1912 eruption of Novarupta were intensely active throughout the Valley of Ten Thousand Smokes (VTTS) when first studied in 1917. Fumarole temperatures recorded in 1919 were as hot as 645??C. Influx of surface waters into the hot ash-flow sheet provided the fluid flow to sustain the fumaroles but also enhanced cooling so that by the mid-1930's vigorous activity survived only in the vent region. Configuration and distribution of high-temperature fissure fumaroles tens of meters long, that are prevalent in the middle and upper VTTS, were controlled largely by sintering and degree of welding, which in turn controlled fracturing and permeability of the ash-flow tuff. One fracture type developed parallel to the enclosing valley walls during compaction of the ash-flow sheet. Another type extends across the VTTS nearly perpendicular to the flow direction. A third type of randomly oriented fractures developed as cooling contraction cracks during vapor-phase devitrification. In distal parts of the ash-flow sheet where the tuff is nonwelded, prominent fumaroles have irregular funnel-shaped morphologies. Fumarole distribution in the nonwelded part of the ash-flow sheet is concentrated above pre-emplacement river channels. The hottest, longest-lived fumaroles occurred in the upper VTTS near the 1912 vent where the ash-flow sheet is thicker, more indurated, and on average more mafic (richer in dacite and andesite) in contrast to the thinner, nonwelded rhyolitic tuff in the distal part of the sheet. Fumarolic activity was less intense in the distal part of the tuff because of lower emplacement temperatures, more diffuse fumarole conduits in the nonwelded tuff, and the thinness of the ash-flow sheet. Chemical leaching of ash-flow tuff by hot rising fluids took place adjacent to fumarolic conduits in deep parts of the fumaroles. Deposition of incrustation minerals, the components of which were carried upward by fumarolic gases

  20. Seasonality of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Mason, B. G.; Pyle, D. M.; Dade, W. B.; Jupp, T.

    2004-04-01

    An analysis of volcanic activity during the last three hundred years reveals that volcanic eruptions exhibit seasonality to a statistically significant degree. This remarkable pattern is observed primarily along the Pacific "Ring of Fire" and locally at some individual volcanoes. Globally, seasonal fluctuations amount to 18% of the historical average monthly eruption rate. In some regions, seasonal fluctuations amount to as much as 50% of the average eruption rate. Seasonality principally reflects the temporal distribution of the smaller, dated eruptions (volcanic explosivity index of 0-2) that dominate the eruption catalog. We suggest that the pattern of seasonality correlates with the annual Earth surface deformation that accompanies the movement of surface water mass during the annual hydrological cycle and illustrate this with respect to global models of surface deformation and regional measurements of annual sea level change. For example, seasonal peaks in the eruption rate of volcanoes in Central America, the Alaskan Peninsula, and Kamchatka coincide with periods of falling regional sea level. In Melanesia, in contrast, peak numbers of volcanic eruptions occur during months of maximal regional sea level and falling regional atmospheric pressure. We suggest that the well-documented slow deformation of Earth's surface that accompanies the annual movements of water mass from oceans to continents acts to impose a fluctuating boundary condition on volcanoes, such that volcanic eruptions tend to be concentrated during periods of local or regional surface change rather than simply being distributed randomly throughout the year. Our findings have important ramifications for volcanic risk assessment and volcanoclimate feedback mechanisms.

  1. Monitoring and Characterizing the Geysering and Seismic Activity at the Lusi Mud Eruption Site, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Karyono, Karyono; Obermann, Anne; Mazzini, Adriano; Lupi, Matteo; Syafri, Ildrem; Abdurrokhim, Abdurrokhim; Masturyono, Masturyono; Hadi, Soffian

    2016-04-01

    The Lusi eruption began on May 29, 2006 in the northeast of Java Island, Indonesia, and to date is still active. Lusi is a newborn sedimentary-hosted hydrothermal system characterized by continuous expulsion of liquefied mud and breccias and geysering activity. Lusi is located upon the Watukosek fault system, a left lateral wrench system connecting the volcanic arc and the bakarc basin. This fault system is still periodically reactivated as shown by field data. In the framework of the Lusi Lab project (ERC grant n° 308126) we conducted several types of monitoring. Based on camera observations, we characterized the Lusi erupting activity by four main behaviors occurring cyclically: (1) Regular activity, which consists in the constant emission of water and mud breccias (i.e. viscous mud containing clay, silt, sand and clasts) associated with the constant expulsion of gas (mainly aqueous vapor with minor amounts of CO2 and CH4) (2) Geysering phase with intense bubbling, consisting in reduced vapor emission and more powerful bursting events that do not seem to have a regular pattern. (3) Geysering phase with intense vapor and degassing discharge and a typically dense plume that propagates up to 100 m height. (4) Quiescent phase marking the end of the geysering activity (and the observed cycle) with no gas emissions or bursts observed. To investigate the possible seismic activity beneath Lusi and the mechanisms controlling the Lusi pulsating behaviour, we deployed a network of 5 seismic stations and a HD camera around the Lusi crater. We characterize the observed types of seismic activity as tremor and volcano-tectonic events. Lusi tremor events occur in 5-10 Hz frequency band, while volcano tectonic events are abundant in the high frequencies range from 5 Hz until 25 Hz. We coupled the seismic monitoring with the images collected with the HD camera to study the correlation between the seismic tremor and the different phases of the geysering activity. Key words: Lusi

  2. 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

  3. Modelling of Subglacial Volcanic and Geothermal Activity, during the 2014-15 Bárdarbunga-Holuhraun Eruption and Caldera Collapse

    NASA Astrophysics Data System (ADS)

    Reynolds, H. I.; Gudmundsson, M. T.; Hognadottir, T.

    2015-12-01

    Seismic unrest was observed within the subglacial caldera of Bárdarbunga on 16 August 2014, followed by seismicity tracing the path of a lateral dyke extending underneath the Vatnajökull glacier out to 45 km to the north east of the volcano. A short subaerial fissure eruption occurred at the site of the Holuhraun lavas, just north of the glacier edge on 29 August, before recommencing in earnest on 31 August with a large effusive eruption and accompanying slow caldera collapse, which lasted for approximately 6 months. The glacier surface around Bárdarbunga was monitored using aerial altimeter profiling. Several shallow depressions, known as ice cauldrons, formed around the caldera rim and on Dyngjujökull glacier above the dyke propagation path. The cauldrons range in volume from approximately 0.0003 km3 to 0.02 km3. Two types of melting were observed: high initial heat flux over a period of days which gradually disappears; and slower but more sustained melting rates. 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 these cauldrons is not obvious. Two scenarios are explored: 1) small subglacial eruptions; or 2) increased geothermal activity induced by the dyke intrusion. We investigate these scenarios using numerical modelling, considering the surface heat flux produced, and timescales and spatial extent of associated surface anomalies. It is found that a magmatic intrusion into rocks where the groundwater is near the boiling point curve can cause rapid increase in geothermal activity, but even a shallow intrusion into a cold groundwater reservoir will have a muted thermal response. Thus, our results indicate that minor subglacial eruptions are the most plausible explanation for the observed rapid melting far from known geothermal areas. These results have implications for the interpretation of thermal signals observed at ice

  4. Seismic activity during the recent eruptive period at Volcán de Colima, México

    NASA Astrophysics Data System (ADS)

    Arambula, R.; Reyes, G.; González, M.; Ramirez, C.; Martínez, A.

    2013-12-01

    Volcán de Colima is an andesitic volcano and is located in the Western part of Mexico, between the states of Jalisco and Colima. It is considered the most active in Mexico based upon its more than 40 effusive and explosive eruptive episodes in the past 500 years. Based upon its last period of activity (2007-2011), the volcano is considered as an open system. On January 3, 2013, a new period of activity started at Volcán of Colima, with the occurrence of Long-Period events (LPs) of low amplitude and proximal Volcano-Tectonic events (VTs) under the crater. An exponential growth of the continuous seismic signal (RMS) of nearest station was observed during the next three days. Finally, a moderately-sized vulcanian explosion occurred with pyroclastic flows emplaced mainly to the west. Then, another three moderate explosions partially destroyed the lava dome formed during the activity of 2007-2011. In late January a new lava dome started to grow inside the fresh crater; the seismic activity associated with this new lava dome was composed of mainly LPs. Some distal VTs have also been observed within 30 kilometers of the volcano. The emission rate has been estimated at less than 0.1 m3/s. During the first days of April, lava flows commenced to the west and southwest of the volcano. Rockfalls and some small pyroclastic flows followed reaching the base of the volcanic edifice. With a program based on Hidden Markov Models (HMMs) more than 100 rockfalls have been recognized automatically per day, also more than 1538 explosions have occurred up to July 30 with a mean of 7 daily. These explosions originated from depths less than 3 km below the crater, determined using the seismic amplitude method. The maximum energy of these explosions was 1.5e+9 Joules for the explosion on January 29. The most energetic explosions also had Very-Long-Period events (VLPs) associated with them with periods of between 30 and 10 sec. The accumulated energy of all the explosions is 3.9e+9 Joules

  5. 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.

  6. Formation and Eruption of an Active Region Sigmoid. I. A Study by Nonlinear Force-free Field Modeling

    NASA Astrophysics Data System (ADS)

    Jiang, Chaowei; Wu, S. T.; Feng, Xueshang; Hu, Qiang

    2014-01-01

    We present a comprehensive study of the formation and eruption of an active region (AR) sigmoid in AR 11283. To follow the quasi-static evolution of the coronal magnetic field, we reconstruct a time sequence of static fields using a recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis of the fields compared with observations suggests the following scenario for the evolution of the region. Initially, a new bipole emerges into the negative polarity of a preexisting bipolar AR, forming a null-point topology between the two flux systems. A weakly twisted flux rope (FR) is then built up slowly in the embedded core region, largely through flux cancellation, forming a bald patch separatrix surface (BPSS). The FR grows gradually until its axis runs into a torus instability (TI) domain, and the BPSS also develops a full S-shape. The combined effects of the TI-driven expansion of the FR and the line tying at the BP tear the FR into two parts with the upper portion freely expelled and the lower portion remaining behind the postflare arcades. This process dynamically perturbs the BPSS and results in the enhanced heating of the sigmoid and the rope. The accelerated expansion of the upper-portion rope strongly pushes its envelope flux near the null point and triggers breakout reconnection at the null, which further drives the eruption. We discuss the important implications of these results for the formation and disruption of the sigmoid region with an FR.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  8. Photogrammetry surveys and mosaic: a useful tool to monitor active zones. Applications to the Indonesian Lusi eruption site.

    NASA Astrophysics Data System (ADS)

    Romeo, Giovanni; Di Stefano, Giuseppe; Mazzini, Adriano; Iarocci, Alessandro; Caramelli, Antonio

    2016-04-01

    Unmanned and remotely operated aircraft showed to be an efficient and cost effective way to explore remote or extreme environments. Comparative photogrammetry studies are an efficient way to study and monitor he evolution of geologically active areas and ongoing events and are able to highlight details that are typically lost during traditional field campaigns. The Lusi mud eruption in eastern Java (Indonesia) represents one of the most spectacular geological phenomena that is ongoing since May 2006. In the framework of the Lusi Lab project (ERC grant n° 308126) we designed and constructed a multipurpose drone to survey the eruption site. Among the numerous other payloads, the Lusi drone is equipped with Olympus EPM-2 and Go-Pro Hero3 cameras that allow the operator to collect video stills, high quality pictures and to complete photogrammetry surveys. Targeted areas have been selected for detailed studies in the 7 km2 region inside the embankment that was prevent the mud burial of the settlements in the Sidoarjo Regency. The region is characterized by the presence of the Watukosek fault zone. This strike slip system originates from the Arjuno-Welirang volcanic complex and extends to the north east of the Java Island intersecting the Lusi crater. Therefore of particular interest are the faulted surveyed areas present around the Lusi crater inside the embankment. Results reveal a surprising accuracy for the collected mosaic. Multiple surveys are able to reveal the changes and the evolution of the fault through time and to indicate more active zones. In particular this type of survey can highlight the weakness zones and is thus useful to prevent potential geohazards in the area. The poster shows the aerial survey results, including a 3d-printed slice of LuSi, obtained combining 2500 16 Mp photographs. A 3d zoomed detail is also shown, evidencing the resolution that this technique can offer.

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

    USGS Publications Warehouse

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

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Guffanti, Marianne; Ewert, John W.; Gallina, Gregory M.; Bluth, Gregg J. S.; Swanson, Grace L.

    2005-08-01

    Within the Commonwealth of the Northern Mariana Islands (CNMI), Anatahan is one of nine active subaerial volcanoes that pose hazards to major air-traffic routes from airborne volcanic ash. The 2003-2004 eruptive activity of Anatahan volcano affected the region's aviation operations for 3 days in May 2003. On the first day of the eruption (10 May 2003), two international flights from Saipan to Japan were cancelled, and several flights implemented ash-avoidance procedures. On 13 May 2003, a high-altitude flight through volcanic gas was reported, with no perceptible damage to the aircraft. TOMS and MODIS analysis of satellite data strongly suggests that no significant ash and only minor amounts of SO 2 were involved in the incident, consistent with crew observations. On 23 May 2003, airport operations were disrupted when tropical-cyclone winds dispersed ash to the south, dusting Saipan with light ashfall and causing flight cancellations there and at Guam 320 km south of the volcano. Operational (near-real-time) monitoring of ash clouds produced by Anatahan has been conducted since the first day of the eruption on 10 May 2003 by the Washington Volcanic Ash Advisory Center (VAAC). The VAAC was among the first groups outside of the immediate area of the volcano to detect and report on the unexpected eruption of Anatahan. After being contacted about an unusual cloud by National Weather Service forecasters in Guam at 1235 UTC on 10 May 2003, the VAAC analyzed GOES 9 images, confirming Anatahan as the likely source of an ash cloud and estimating that the eruption began at about 0730 UTC. The VAAC issued its first Volcanic Ash Advisory for Anatahan at 1300 UTC on 10 May 2003 more than 5 h after the start of the eruption, the delay reflecting the difficulty of detecting and confirming a surprise eruption at a remote volcano with no in situ real-time geophysical monitoring. The initial eruption plume reached 10.7-13.4 km (35,000-44,000 ft), well into jet cruise altitudes

  11. 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

  12. Crater lake and post-eruption hydrothermal activity, El Chichón Volcano, Mexico

    USGS Publications Warehouse

    Casadevall, Thomas J.; de la Cruz-Reyna, Servando; Rose, William I., Jr.; Bagley, Susan; Finnegan, David L.; Zoller, William H.

    1984-01-01

    Explosive eruptions of Volcán El Chichón in Chiapas, Mexico on March 28 and April 3–4, 1982 removed 0.2 km3 of rock to form a 1-km-wide 300-m-deep summit crater. By late April 1982 a lake had begun to form on the crater floor, and by November 1982 it attained a maximum surface area of 1.4 × 105 m2 and a volume of 5 × 106 m3. Accumulation of 4–5 m of rainfall between July and October 1982 largely formed the lake. In January 1983, temperatures of fumaroles on the crater floor and lower crater walls ranged from 98 to 115°C; by October 1983 the maximum temperature of fumarole emissions was 99°C. In January 1983 fumarole gas emissions were greater than 99 vol. % H2O with traces of CO2, SO2, and H2S. The water of the lake was a hot (T = 52–58°C), acidic (pH = 0.5), dilute solution (34,046 mg L−1 dissolved solids; Cl/S = 20.5). Sediment from the lake contains the same silicate minerals as the rocks of the 1982 pyroclastic deposits, together with less than 1% of elemental sulfur. The composition and temperature of the lake water is attributed to: (1) solution of fumarole emissions; (2) reaction of lake water with hot rocks beneath the lake level; (3) sediments washed into the lake from the crater walls; (4) hydrothermal fluids leaching sediments and formational waters in sedimentary rocks of the basement; (5) evaporation; and (6) precipitation.

  13. 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.

  14. 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.

  15. 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.

  16. Active Submarine Volcanoes and Electro-Optical Sensor Networks: The Potential of Capturing and Quantifying an Entire Eruptive Sequence at Axial Seamount, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Delaney, J. R.; Kelley, D. S.; Proskurowski, G.; Fundis, A. T.; Kawka, O.

    2011-12-01

    The NE Pacific Regional Scale Nodes (RSN) component of the NSF Ocean Observatories Initiative is designed to provide unprecedented electrical power and bandwidth to the base and summit of Axial Seamount. The scientific community is engaged in identifying a host of existing and innovative observation and measurement techniques that utilize the high-power and bandwidth infrastructure and its real-time transmission capabilities. The cable, mooring, and sensor arrays will enable the first quantitative documentation of myriad processes leading up to, during, and following a submarine volcanic event. Currently planned RSN instrument arrays will provide important and concurrent spatial and temporal constraints on earthquake activity, melt migration, hydrothermal venting behavior and chemistry, ambient currents, microbial community structure, high-definition (HD) still images and HD video streaming from the vents, and water-column chemistry in the overlying ocean. Anticipated, but not yet funded, additions will include AUVs and gliders that continually document the spatial-temporal variations in the water column above the volcano and the distal zones. When an eruption appears imminent the frequency of sampling will be increased remotely, and the potential of repurposing the tracking capabilities of the mobile sensing platforms will be adapted to the spatial indicators of likely eruption activity. As the eruption begins mobile platforms will fully define the geometry, temperature, and chemical-microbial character of the volcanic plume as it rises into the thoroughly documented control volume above the volcano. Via the Internet the scientific community will be able to witness and direct adaptive sampling in response to changing conditions of plume formation. A major goal will be to document the eruptive volume and link the eruption duration to the volume of erupted magma. For the first time, it will be possible to begin to quantify the time-integrated output of an underwater

  17. Eruption processes and deposit characteristics at the monogenetic Mt. Gambier Volcanic Complex, SE Australia: implications for alternating magmatic and phreatomagmatic activity

    NASA Astrophysics Data System (ADS)

    van Otterloo, Jozua; Cas, Raymond A. F.; Sheard, Malcolm J.

    2013-08-01

    The ˜5 ka Mt. Gambier Volcanic Complex in the Newer Volcanics Province, Australia is an extremely complex monogenetic, volcanic system that preserves at least 14 eruption points aligned along a fissure system. The complex stratigraphy can be subdivided into six main facies that record alternations between magmatic and phreatomagmatic eruption styles in a random manner. The facies are (1) coherent to vesicular fragmental alkali basalt (effusive/Hawaiian spatter and lava flows); (2) massive scoriaceous fine lapilli with coarse ash (Strombolian fallout); (3) bedded scoriaceous fine lapilli tuff (violent Strombolian fallout); (4) thin-medium bedded, undulating very fine lapilli in coarse ash (dry phreatomagmatic surge-modified fallout); (5) palagonite-altered, cross-bedded, medium lapilli to fine ash (wet phreatomagmatic base surges); and (6) massive, palagonite-altered, very poorly sorted tuff breccia and lapilli tuff (phreato-Vulcanian pyroclastic flows). Since most deposits are lithified, to quantify the grain size distributions (GSDs), image analysis was performed. The facies are distinct based on their GSDs and the fine ash to coarse+fine ash ratios. These provide insights into the fragmentation intensities and water-magma interaction efficiencies for each facies. The eruption chronology indicates a random spatial and temporal sequence of occurrence of eruption styles, except for a "magmatic horizon" of effusive activity occurring at both ends of the volcanic complex simultaneously. The eruption foci are located along NW-SE trending lineaments, indicating that the complex was fed by multiple dykes following the subsurface structures related to the Tartwaup Fault System. Possible factors causing vent migration along these dykes and changes in eruption styles include differences in magma ascent rates, viscosity, crystallinity, degassing and magma discharge rate, as well as hydrological parameters.

  18. 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

  19. Volcanic Eruptions and Climate

    NASA Technical Reports Server (NTRS)

    LeGrande, Allegra N.; Anchukaitis, Kevin J.

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  1. 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

  2. Polymorphic light eruption

    MedlinePlus

    ... outdoors. Wear a sun hat. Wear sunglasses with UV protection. Use a lip balm with sunscreen. Alternative Names Polymorphic light eruption; Photodermatosis; PMLE Images Polymorphic light eruption on ...

  3. Improvement forecasting of volcanic activity by applying a Kalman filter to the SSEM signal. The case of the El Hierro Island eruption (October 2011)

    NASA Astrophysics Data System (ADS)

    Garcia, A.; Berrocoso, M.; Marrero, J. M.; Ortiz, R.

    2012-04-01

    The FFM (Failure Forecast Method) is developed from the eruption of St. Helens, being repeatedly applied to forecast eruptions and recently to the prediction of seismic activity in active volcanic areas. The underwater eruption of El Hierro Island has been monitored from three months before starting (October 10, 2011). This allowed a large catalogue of seismic events (over 11000) and continuous recording seismic signals that cover the entire period. Since the beginning of the seismic-volcanic crisis (July 2011), the FFM was applied to the SSEM signal of seismic records. Mainly because El Hierro is a very small island, the SSEM has a high noise (traffic and oceanic noise). To improve the signal / noise ratio has been used a Kalman filter. The Kalman filter coefficients are adjusted using an inversion process based on forecasting errors occurred in the twenty days preceding. The application of this filter has been a significant improvement in the reliability of forecasts. The analysis of the results shows, before the start of the eruption, that 90% of the forecasts are obtained with errors less than 10 minutes with more than 24 hours in advance. It is noteworthy that the method predicts the events of greater magnitude and especially the beginning of each swarm of seismic events. At the time the eruption starts reducing the efficiency of the forecast 50% with a dispersion of more than one hour. This fact is probably due to decreased detectability by saturation of some of the seismic stations and decreased the average magnitude. However, the events of magnitude greater than 4 were predicted with an error less than 20 minutes.

  4. Carbonate-derived CO 2 purging magma at depth: Influence on the eruptive activity of Somma-Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Dallai, Luigi; Cioni, Raffaello; Boschi, Chiara; D'Oriano, Claudia

    2011-10-01

    Mafic phenocrysts from selected products of the last 4 ka volcanic activity at Mt. Vesuvius were investigated for their chemical and O-isotope composition, as a proxy for primary magmas feeding the system. 18O/ 16O ratios of studied Mg-rich olivines suggest that near-primary shoshonitic to tephritic melts experienced a flux of sedimentary carbonate-derived CO 2, representing the early process of magma contamination in the roots of the volcanic structure. Bulk carbonate assimilation (physical digestion) mainly occurred in the shallow crust, strongly influencing magma chamber evolution. On a petrological and geochemical basis the effects of bulk sedimentary carbonate digestion on the chemical composition of the near-primary melts are resolved from those of carbonate-released CO 2 fluxed into magma. An important outcome of this process lies in the effect of external CO 2 in changing the overall volatile solubility of the magma, enhancing the ability of Vesuvius mafic magmas to rapidly rise and explosively erupt at the surface.

  5. 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

  6. Hydrothermal activity at Campi Flegrei caldera: rock mechanical properties and implications for outgassing and possible phreatic eruptions

    NASA Astrophysics Data System (ADS)

    Mayer, K.; Montanaro, C.; Scheu, B.; Isaia, R.; Mangiacapra, A.; Gresse, M.; Vandemeulebrouck, J.; Moretti, R.; Dingwell, D. B.

    2015-12-01

    The Solfatara and Pisciarelli fumaroles are the main surface manifestations of the vigorous hydrothermal activity within the Campi Flegrei caldera system. The existing fault system appears to have a major control on outgassing and leads to a strong alteration of the volcanic products in both areas. Consistent with the volcanic history of the area, Solfatara and Pisciarelli are posited as having the highest probability for the opening of new vents, and in particular for possible phreatic activity within the Campi Flegrei system. Hydrothermal alteration deeply affects all the rocks exposed within Solfatara sector, including lava domes, breccias, as well as pyroclastic fallout ash beds and pyroclastic density current deposits. This results in changes of the volcanic rock's original microstructure and of their physical and mechanical properties, which in turn control both the outgassing and their fragmentation behaviors. Here, samples from the wall rocks in the vicinity of the Solfatara and Pisciarelli fumaroles have been subjected to geochemical, physical and mechanical properties characterization. In addition, surficial Solfatara crater floor deposits were characterized and their properties, in particular permeability, were mapped. Results show that hydrothermal alteration increases porosity and permeability of the crater wall samples favoring outgassing, while decreasing the rock strength. At the crater floor the outgassing occurs mainly along the crack system, which has also generated crusted hummocks. Elsewhere the fluid circulation in the subsoil is favored by the presence of coarse and sulfur-hardened levels, whereas their surfacing is hindered by compacted fine-grained, low permeability layers. Decompression experiments were performed to simulate a phreatic eruption at shallow depth. We used crater-wall samples representing the rocks in the proximity of high degassing areas. Changes in the fragmentation behavior and ejection dynamics, depending on the

  7. Jupiter Eruptions

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on the image for high resolution image of Nature Cover

    Detailed analysis of two continent-sized storms that erupted in Jupiter's atmosphere in March 2007 shows that Jupiter's internal heat plays a significant role in generating atmospheric disturbances. Understanding these outbreaks could be the key to unlock the mysteries buried in the deep Jovian atmosphere, say astronomers.

    This visible-light image is from NASA's Hubble Space Telescope taken on May 11, 2007. It shows the turbulent pattern generated by the two plumes on the upper left part of Jupiter.

    Understanding these phenomena is important for Earth's meteorology where storms are present everywhere and jet streams dominate the atmospheric circulation. Jupiter is a natural laboratory where atmospheric scientists study the nature and interplay of the intense jets and severe atmospheric phenomena.

    According to the analysis, the bright plumes were storm systems triggered in Jupiter's deep water clouds that moved upward in the atmosphere vi gorously and injected a fresh mixture of ammonia ice and water about 20 miles (30 kilometers) above the visible clouds. The storms moved in the peak of a jet stream in Jupiter's atmosphere at 375 miles per hour (600 kilometers per hour). Models of the disturbance indicate that the jet stream extends deep in the buried atmosphere of Jupiter, more than 60 miles (approximately100 kilometers) below the cloud tops where most sunlight is absorbed.

  8. 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.

  9. 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.

  10. EVOLUTION OF MAGNETIC FIELD AND ENERGY IN A MAJOR ERUPTIVE ACTIVE REGION BASED ON SDO/HMI OBSERVATION

    SciTech Connect

    Sun Xudong; Hoeksema, J. Todd; Liu, Yang; Hayashi, Keiji; Wiegelmann, Thomas; Thalmann, Julia; Chen Qingrong

    2012-04-01

    We report the evolution of the magnetic field and its energy in NOAA active region 11158 over five days based on a vector magnetogram series from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO). Fast flux emergence and strong shearing motion led to a quadrupolar sunspot complex that produced several major eruptions, including the first X-class flare of Solar Cycle 24. Extrapolated nonlinear force-free coronal fields show substantial electric current and free energy increase during early flux emergence near a low-lying sigmoidal filament with a sheared kilogauss field in the filament channel. The computed magnetic free energy reaches a maximum of {approx}2.6 Multiplication-Sign 10{sup 32} erg, about 50% of which is stored below 6 Mm. It decreases by {approx}0.3 Multiplication-Sign 10{sup 32} erg within 1 hr of the X-class flare, which is likely an underestimation of the actual energy loss. During the flare, the photospheric field changed rapidly: the horizontal field was enhanced by 28% in the core region, becoming more inclined and more parallel to the polarity inversion line. Such change is consistent with the conjectured coronal field 'implosion' and is supported by the coronal loop retraction observed by the Atmospheric Imaging Assembly (AIA). The extrapolated field becomes more 'compact' after the flare, with shorter loops in the core region, probably because of reconnection. The coronal field becomes slightly more sheared in the lowest layer, relaxes faster with height, and is overall less energetic.

  11. INITIATION AND ERUPTION PROCESS OF MAGNETIC FLUX ROPE FROM SOLAR ACTIVE REGION NOAA 11719 TO EARTH-DIRECTED CME

    SciTech Connect

    Vemareddy, P.; Zhang, J.

    2014-12-20

    An eruption event launched from the solar active region (AR) NOAA 11719 is investigated based on coronal EUV observations and photospheric magnetic field measurements obtained from the Solar Dynamic Observatory. The AR consists of a filament channel originating from a major sunspot and its south section is associated with an inverse-S sigmoidal system as observed in Atmospheric Imaging Assembly passbands. We regard the sigmoid as the main body of the flux rope (FR). There also exists a twisted flux bundle crossing over this FR. This overlying flux bundle transforms in shape similar to kink-rise evolution, which corresponds with the rise motion of the FR. The emission measure and temperature along the FR exhibits an increasing trend with its rising motion, indicating reconnection in the thinning current sheet underneath the FR. Net magnetic flux of the AR, evaluated at north and south polarities, showed decreasing behavior whereas the net current in these fluxes exhibits an increasing trend. Because the negative (positive) flux has a dominant positive (negative) current, the chirality of AR flux system is likely negative (left handed) in order to be consistent with the chirality of inverse S-sigmoidal FR. This analysis of magnetic fields of the source AR suggests that the cancelling fluxes are prime factors of the monotonous twisting of the FR system, reaching to a critical state to trigger kink instability and rise motion. This rise motion may have led to the onset of the torus instability, resulting in an Earth-directed coronal mass ejection, and the progressive reconnection in the thinning current sheet beneath the rising FR led to the M6.5 flare.

  12. Using a combined population-based and kinetic modelling approach to assess timescales and durations of magma migration activities prior to the 1669 flank eruption of Mt. Etna

    NASA Astrophysics Data System (ADS)

    Kahl, M.; Morgan, D. J.; Viccaro, M.; Dingwell, D. B.

    2015-12-01

    The March-July eruption of Mt. Etna in 1669 is ranked as one of the most destructive and voluminous eruptions of Etna volcano in historical times. To assess threats from future eruptions, a better understanding of how and over what timescales magma moved underground prior to and during the 1669 eruption is required. We present a combined population based and kinetic modelling approach [1-2] applied to 185 olivine crystals that erupted during the 1669 eruption. By means of this approach we provide, for the first time, a dynamic picture of magma mixing and magma migration activity prior to and during the 1669 flank eruption of Etna volcano. Following the work of [3] we have studied 10 basaltic lava samples (five SET1 and five SET2 samples) that were erupted from different fissures that opened between 950 and 700 m a.s.l. Following previous work [1-2] we were able to classify different populations of olivine based on their overall core and rim compositional record and the prevalent zoning type (i.e. normal vs. reverse). The core plateau compositions of the SET1 and SET2 olivines range from Fo70 up to Fo83 with a single peak at Fo75-76. The rims differ significantly and can be distinguished into two different groups. Olivine rims from the SET1 samples are generally more evolved and range from Fo50 to Fo64 with a maximum at Fo55-57. SET2 olivine rims vary between Fo65-75 with a peak at Fo69. SET1 and SET2 olivines display normal zonation with cores at Fo75-76 and diverging rim records (Fo55-57 and Fo65-75). The diverging core and rim compositions recorded in the SET1 and SET2 olivines can be attributed to magma evolution possibly in three different magmatic environments (MEs): M1 (=Fo75-76), M2 (=Fo69) and M3 (=Fo55-57) with magma transfer and mixing amongst them. The MEs established in this study differ slightly from those identified in previous works [1-2]. We note the relative lack of olivines with Fo-rich core and rim compositions indicating a major mafic magma

  13. Assessing Eruption Column Height in Ancient Flood Basalt Eruptions

    NASA Technical Reports Server (NTRS)

    Glaze, Lori S.; Self, Stephen; Schmidt, Anja; Hunter, Stephen J.

    2015-01-01

    A buoyant plume model is used to explore the ability of flood basalt eruptions to inject climate-relevant gases into the stratosphere. An example from the 1986 Izu-Oshima basaltic fissure eruption validates the model's ability to reproduce the observed maximum plume heights of 12-16 km above sea level, sustained above fire-fountains. The model predicts maximum plume heights of 13-17 km for source widths of between 4-16 m when 32% (by mass) of the erupted magma is fragmented and involved in the buoyant plume (effective volatile content of 6 wt%). Assuming that the Miocene-age Roza eruption (part of the Columbia River Basalt Group) sustained fire-fountains of similar height to Izu-Oshima (1.6 km above the vent), we show that the Roza eruption could have sustained buoyant ash and gas plumes that extended into the stratosphere at approximately 45 deg N. Assuming 5 km long active fissure segments and 9000 Mt of SO2 released during explosive phases over a 10-15 year duration, the approximately 180 km of known Roza fissure length could have supported approximately 36 explosive events/phases, each with a duration of 3-4 days. Each 5 km fissure segment could have emitted 62 Mt of SO2 per day into the stratosphere while actively fountaining, the equivalent of about three 1991 Mount Pinatubo eruptions per day. Each fissure segment could have had one to several vents, which subsequently produced lava without significant fountaining for a longer period within the decades-long eruption. Sensitivity of plume rise height to ancient atmospheric conditions is explored. Although eruptions in the Deccan Traps (approximately 66 Ma) may have generated buoyant plumes that rose to altitudes in excess of 18 km, they may not have reached the stratosphere because the tropopause was substantially higher in the late Cretaceous. Our results indicate that some flood basalt eruptions, such as Roza, were capable of repeatedly injecting large masses of SO2 into the stratosphere. Thus sustained

  14. Continuous overnight observation of human premolar eruption.

    PubMed

    Risinger, R K; Proffit, W R

    1996-01-01

    Such observation was made possible by transmitting the image of a mobile ceramic ruling on the erupting maxillary second premolar to a video-microscope via a coaxial fibreoptic cable. The cable was inserted into a reference bar secured to the adjacent first molar and first premolar. The image of the ruling was superimposed with the image from a surveillance camera focused on the patient and continuously recorded on video-tape along with the participant's blood pressure, pulse rate, electromyographic activity and occlusal contact sounds. Overnight data from 12 individuals clearly revealed a circadian rhythm in eruption during the prefunctional spurt. On average, the maxillary second premolar erupted 41 microns during an 11-h overnight observation, with almost all the eruption occurring in the late evening from 8 p.m. to 1 a.m. After 1 a.m., eruption typically ceased, with a tendency for intrusion to occur until 7 a.m. Sleep increased the rate of eruption during the late evening, but did not influence the eruption rate during the early morning. Haemodynamic changes, including blood pressure and pulse rate, did not have a significant impact on the rhythm of eruption. The observed eruption rhythm is most probably caused by changing hormone levels and their effect on the periodontal ligament. The late-evening eruption of human premolars coincides with the late-evening secretion of growth hormone and thyroid hormone typically found in humans. PMID:9022915

  15. Postglacial eruptive history, geochemistry, and recent seismicity of Aniakchak volcano, Alaska Peninsula

    USGS Publications Warehouse

    Bacon, Charles R.; Neal, Christina A.; Miller, Thomas P.; McGimsey, Robert G.; Nye, Christopher J.

    2014-01-01

    Future volcanic activity of Aniakchak could include hydromagmatic explosions, possibly followed by effusion or strombolian eruption of basaltic andesite to Plinian eruption of dacite. Another voluminous eruption, such as Aniakchak II, is considered unlikely in the near future.

  16. 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

  17. Regional-scale advective, diffusive, and eruptive dynamics of CO2 and brine leakage through faults and wellbores

    NASA Astrophysics Data System (ADS)

    Jung, Na-Hyun; Han, Weon Shik; Han, Kyungdoe; Park, Eungyu

    2015-05-01

    Regional-scale advective, diffusive, and eruptive transport dynamics of CO2 and brine within a natural analogue in the northern Paradox Basin, Utah, were explored by integrating numerical simulations with soil CO2 flux measurements. Deeply sourced CO2 migrates through steeply dipping fault zones to the shallow aquifers predominantly as an aqueous phase. Dense CO2-rich brine mixes with regional groundwater, enhancing CO2 dissolution. Linear stability analysis reveals that CO2 could be dissolved completely within only ~500 years. Assigning lower permeability to the fault zones induces fault-parallel movement, feeds up-gradient aquifers with more CO2, and impedes down-gradient fluid flow, developing anticlinal CO2 traps at shallow depths (<300 m). The regional fault permeability that best reproduces field spatial CO2 flux variation is estimated 1 × 10-17 ≤ kh < 1 × 10-16 m2 and 5 × 10-16 ≤ kv < 1 × 10-15 m2. The anticlinal trap serves as an essential fluid source for eruption at Crystal Geyser. Geyser-like discharge sensitively responds to varying well permeability, radius, and CO2 recharge rate. The cyclic behavior of wellbore CO2 leakage decreases with time.

  18. Will Teide erupt again?

    NASA Astrophysics Data System (ADS)

    Marti, Joan; Geyer, Adelina

    2016-04-01

    The quantification of hazard in volcanic systems characterised by long repose period is difficult because the lack of knowledge of the past volcanic history and also because in many cases volcanism is not perceived as a potential problem, being only regarded as an attraction for tourism or a source of economic benefit, thus hiding the need to conduct hazard assessment. Teide, in the island of Tenerife (Canary Islands), is not an exception to this general rule and, despite being one of the largest composite volcanoes in the World, it is generally considered as a non-active volcano by population, visitors and even by some scientists. However, geological and geophysical evidence, including a large diversity of monitoring signals recorded during last decades, as well as a simple comparison with similar volcanoes that have erupted in recent times after hundreds or even thousands of years of quiescence, recommend to consider Teide as an active volcano and to take the necessary precaution in an island with nearly one million of permanent inhabitants and nearly 5 millions of visitors per year. What is the potential of Teide to erupt again? is the question that relies behind the fact of considering it as active, and that needs to be answered first. Based on the current volcanological, petrological and geophysical knowledge We propose a conceptual model on the magma recharge mechanisms, structure of the plumbing system, and eruption triggers and dynamics of Teide volcano that helps to understand its behaviour and to anticipate future activity. Ramón y Cajal contract (RYC-2012-11024)

  19. Lava dome morphometry and geochronology of the youngest eruptive activity in Eastern Central Europe: Ciomadul (Csomád), East Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Karátson, D.; Telbisz, T.; Harangi, Sz.; Magyari, E.; Kiss, B.; Dunkl, I.; Veres, D.; Braun, M.

    2012-04-01

    Volcanic evolution of the Ciomadul (Csomád) lava dome complex, site of the youngest (Late Pleistocene, late Marine Isotope Stage 3) eruptive activity in the Carpathians, has been studied by advanced morphometry and radiometric (U/Pb, U/He and 14C) geochronology. The volcano produced alternating effusive and intermittent explosive eruptions from individual domes, typical of common andesitic-dacitic lava domes. A comparative morphometry shows steep ≥30° mean slopes of domes' upper flank and the Csomád domes fit well to the 100-200 ka domes worldwide. Morphometric ages obtained from the mean slope vs age precipitation correlation results in ≤100 ka ages. The morphometric approach is supported by U/Pb and U/He chronology: preliminary results of zircon dating indicate ages ranging between 200(250) and 30 ka. The youngest ages of the data set obtained both from lavas and pumiceous pyroclastics argue for a more or less coeval effusive and explosive volcanism. Based also on volcanological data, we propose vulcanian eruptions and explosive dome collapses especially toward the end of volcanic activity. Moreover, radiometric chronology suggests that, possibly subsequently to the peripheral domes, a central lava dome complex built up ≤100 ka ago. This dome complex, exhibiting even more violent, up to sub-plinian explosions, emplaced pumiceous pyroclastic flow and fall deposits as far as 17 km. We propose that the explosive activity produced caldera-forming eruptions as well, creating a half-caldera. This caldera rim is manifested by the asymmetric morphology of the central edifice: the present-day elevated ridge of Ciomadul Mare (Nagy Csomád), encompassing the twin craters of Mohoş (Mohos) peat bog and Sf. Ana (Szent [St.] Anna). These latter craters may have been formed subsequently, ca. ~100-30 ka ago, after the caldera formation. Drilling of lacustrine sediments in the St. Anna crater shows that beneath the Holocene gyttja several meters of Late Pleistocene

  20. Bayesian analysis of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Ho, Chih-Hsiang

    1990-10-01

    The simple Poisson model generally gives a good fit to many volcanoes for volcanic eruption forecasting. Nonetheless, empirical evidence suggests that volcanic activity in successive equal time-periods tends to be more variable than a simple Poisson with constant eruptive rate. An alternative model is therefore examined in which eruptive rate(λ) for a given volcano or cluster(s) of volcanoes is described by a gamma distribution (prior) rather than treated as a constant value as in the assumptions of a simple Poisson model. Bayesian analysis is performed to link two distributions together to give the aggregate behavior of the volcanic activity. When the Poisson process is expanded to accomodate a gamma mixing distribution on λ, a consequence of this mixed (or compound) Poisson model is that the frequency distribution of eruptions in any given time-period of equal length follows the negative binomial distribution (NBD). Applications of the proposed model and comparisons between the generalized model and simple Poisson model are discussed based on the historical eruptive count data of volcanoes Mauna Loa (Hawaii) and Etna (Italy). Several relevant facts lead to the conclusion that the generalized model is preferable for practical use both in space and time.

  1. Two types of volcanic tremor changed with eruption style during 1986 Izu-Oshima eruption

    NASA Astrophysics Data System (ADS)

    Kurokawa, Aika; Takeo, Minoru; Kurita, Kei

    2016-04-01

    Volcanic tremor provides clues to magma migration pathways so that tremor source location is expected to be an efficient tool for tracking dynamic behavior of magma in evolution of eruptive activity. However, clear evidence, which connects between temporal variation in volcanic tremor and evolution of eruption style, is still lacking. We have analyzed volcanic tremors occurred during 1986 Izu-Oshima eruption using recently digitized data. The results present a clear link between eruption styles, waveform variations and source locations of the tremors. Moreover, precursory activity of the tremors that indicates injection of magma below fissures has been clarified 5 days prior to the fissure eruptions. This demonstrates predominance of tremor activity as an adaptive monitoring tool in volcanic eruption.

  2. Styles of eruptive activity on intraplate volcanoes in the Society and Austral hot spot regions - Bathymetry, petrology, and submersible observations

    NASA Astrophysics Data System (ADS)

    Binard, N.; Hekinian, R.; Cheminee, J. L.; Stoffers, P.

    1992-09-01

    A model relating the style of volcanism to the depth of eruption on large intraplate seamounts is proposed on the basis of submersible observations carried out in the Society and Austral hot spot regions (South Pacific) during the Teahitia II cruise (1988-1989). The bases of volcanic edifices are characterized by broad flat flows formed during a high rate of discharge of a very fluid magma on the sea floor. The edifices' flanks deeper than 500 m are mainly made up of bulbous tubular pillows and large drained lava tunnels occurring on slopes steeper than 60-70 deg. Volcanic ejecta due to hydromagmatic eruptions occur at shallow depths (less than 500 m). Volcanic shards, produced by the shattering of the vesiculated glassy margins of the flows, are observed on the edifices' slopes at all depths (from 3000 m to the sea surface), concentrated between pillows or covering large areas, and forming thin indurated layers of mixed shard, sediment, and hydrothermal deposits.

  3. An erupted compound odontoma.

    PubMed

    Gupta, Anil; Vij, Hitesh; Vij, Ruchieka; Malhotra, Ritika

    2014-01-01

    Odontomas are familiar entities but their eruption into the oral cavity is an extraordinary occurrence, which may be associated with pain, infection, malocclusion, etc. Not many cases of erupted odontomas have been reported in the literature. This paper puts forth a case of erupting odontoma in an attempt to add to the list of reported cases of this unique pathology. PMID:24729109

  4. Eruptive history of the Dieng Mountains region, central Java, and potential hazards from future eruptions

    USGS Publications Warehouse

    Miller, C. Dan; Sushyar, R.; Santoso; Hamidi, S.

    1983-01-01

    The Dieng Mountains region consists of a complex of late Quaternary to recent volcanic stratocones, parasitic vents, and explosion craters. Six age groups of volcanic centers, eruptive products, and explosion craters are recognized in the region based on their morphology, degree of dissection, stratigraphic relationships, and degree of weathering. These features range in age from tens of thousands of years to events that have occurred this century. No magmatic eruptions have occurred in the Dieng Mountains region for at least several thousand years; volcanic activity during this time interval has consisted of phreatic eruptions and non-explosive hydrothermal activity. If future volcanic events are similar to those of the last few thousand years, they will consist of phreatic eruptions, associated small hot mudflows, emission of suffocating gases, and hydrothermal activity. Future phreatic eruptions may follow, or accompany, periods of increased earthquake activity; the epicenters for the seismicity may suggest where eruptive activity will occur. Under such circumstances, the populace within several kilometers of a potential eruption site should be warned of a possible eruption, given instructions about what to do in the event of an eruption, or temporarily evacuated to a safer location.

  5. Eruptive history of the Dieng mountains region, central Java, and potential hazards from future eruptions

    SciTech Connect

    Miller, C.D.; Sukhyar, R.; Santoso; Hamidi, S.

    1983-01-01

    The Dieng Mountains region consists of a complex of late Quaternary to recent volcanic stratocones, parasitic vents, and explosion craters. Six age groups of volcanic centers, eruptive products, and explosion craters are recognized in the region based on their morphology, degree of dissection, stratigraphic relationships, and degree of weathering. These features range in age from tens of thousands of years to events that have occurred this century. No magmatic eruptions have occurred in the Dieng Mountains region for at least several thousand years; volcanic activity during this time interval has consisted of phreatic eruptions and non-explosive hydrothermal activity. If future volcanic events are similar to those of the last few thousand years, they will consist of phreatic eruptions, associated small hot mudflows, emission of suffocating gases, and hydrothermal activity. Future phreatic eruptions may follow, or accompany, periods of increased earthquake activity; the epicenters for the seismicity may suggest where eruptive activity will occur. Under such circumstances, the populace within several kilometers of a potential eruption site should be warned of a possible eruption, given instructions about what to do in the event of an eruption, or temporarily evacuated to a safer location. 6 references, 6 figures, 2 tables.

  6. Andesitic Plinian eruptions at Mt. Ruapehu: quantifying the uppermost limits of eruptive parameters

    NASA Astrophysics Data System (ADS)

    Pardo, Natalia; Cronin, Shane; Palmer, Alan; Procter, Jonathan; Smith, Ian

    2012-07-01

    New tephro-stratigraphic studies of the Tongariro Volcanic Centre (TgVC) on the North Island (New Zealand) allowed reconstruction of some of the largest, andesitic, explosive eruptions of Mt. Ruapehu. Large eruptions were common in the Late Pleistocene, before a transition to strombolian-vulcanian and phreatomagmatic eruptive styles that have predominated over the past 10,000 years. Considering this is the most active volcano in North Island of New Zealand and the uppermost hazard limits are unknown, we identified and mapped the pyroclastic deposits corresponding to the five largest eruptions since ~27 ka. The selected eruptive units are also characterised by distinctive lithofacies associations correlated to different behaviours of the eruptive column. In addition, we clarify the source of the ~10-9.7 ka Pahoka Tephra, identified by previous authors as the product of one of the largest eruptions of the TgVC. The most common explosive eruptions taking place between ~13.6 and ~10 ka cal years BP involved strongly oscillating, partially collapsing eruptive columns up to 37 km high, at mass discharge rates up to 6 × 108 kg/s and magnitudes of 4.9, ejecting minimum estimated volumes of 0.6 km3. Our results indicate that this volcano (as well as the neighbouring andesitic Mt. Tongariro) can generate Plinian eruptions similar in magnitude to the Chaitén 2008 and Askja 1875 events. Such eruptions would mainly produce pyroclastic fallout covering a minimum area of 1,700 km2 ESE of the volcano, where important touristic, agricultural and military activities are based. As for the 1995/1996 eruption, our field data indicate that complex wind patterns were critical in controlling the dispersion of the eruptive clouds, developing sheared, commonly bilobate plumes.

  7. Can rain cause volcanic eruptions?

    USGS Publications Warehouse

    Mastin, Larry G.

    1993-01-01

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

  8. Eruptive History of Ikeda Caldera, Southern Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Inakura, H.; Naruo, H.; Okuno, M.; Kobayashi, T.; Tamura, T.

    2015-12-01

    Ikeda caldera is a small-scale caldera (about 4 km in diameter), located in the southern tip of the Satsuma Peninsula, southern Kyushu, Japan. The information on the onset of the caldera-forming eruption is gone due to the catastrophic eruption, but Ikeda caldera is a relatively small-scale eruption that the information before the eruption may have been conserved. We conducted a geological research to understand the eruptive history of Ikeda caldera, including a study of the processes leading to the catastrophic eruption. Pre-caldera activity began at about 20 cal kBP by Iwamoto ash and the effusion of Senta lava, which may have similar composition as the caldera-forming eruption. The caldera-forming eruption began at 6.4 cal kBP with a phreatic explosion that produced the Ikezaki tephra. The phreatic eruption was followed by Osagari scoria, Mizusako scoria and Ikeda pumice plinian eruption. During the climactic stage, Ikeda ignimbrite was erupted and reclaimed the coastal area at that time, and formed the ignimbrite plateau along the coast. Immediately after this event, four maars were formed to the southeast of the caldera. Yamagawa maar, which is the largest and is located at the southeastern end of the fissure vent, erupted pumiceous base surge (Yamagawa base surge), but other maars ejected small amount of accidental materials. During the late stage of the Ikeda eruption, phreatomagmatic eruption occurred at the bottom of the caldera floor, and erupted the Ikedako ash which covered a wide area. The Central lava dome was generated at the late stage of this eruption. After Ikedako ash deposition, secondary explosion of Ikeda ignimbrite occurred mainly along the coastal area, generating small-scale base surge deposits. About two thousand years after the caldera-forming eruption at 4.8 cal kBP, new magmatic activity began on the margin of the caldera rim, and generated Nabeshimadake lava dome.

  9. Can Satellite-Based Sensors, Hand-Held Thermal Imagers and Thermal Infrared Radiometers Calculate Reliable Eruption Rates at Active Lava Flows, Domes and Lakes?

    NASA Astrophysics Data System (ADS)

    Harris, A. J.

    2004-12-01

    Thermal data provide viable means of extracting eruption rates at active lava flows, domes and lakes. The initial algorithm, developed since 1994, uses total heat flux (Q), extracted from satellite-sensor-derived thermal images of the active lava body to extract eruption rate (E) using E = Q / ρ [c Δ T + f L]. Here ρ and c are lava density and specific heat capacity, Δ T is lava cooling, f is fractional crystallization and L is latent heat of crystallization. Later it was shown that this reduces to a linear relationship: E = a Q + b, where a and b are defined by values assumed for ρ , c, Δ T, f, and L. We present three case studies that: (1) demonstrate the variety of thermal data and activity styles that can be used in this approach, and (2) validate the approach through cross-checks with independent, field-based data: (I) Stromboli: Satellite and thermal imager-based lava flow eruption rates. A safe, easy and rapid method to calculate lava effusion rates using hand-held thermal image data was developed in June 2003 at Stromboli (Italy). FLIR data were used as input to the thermal effusion rate model, previously applied to satellite data, allowing automated effusion rate extraction. A comparison between a thermally-derived (0.2 - 0.9 m3/s) and dimensionally-derived (i.e. channel depth x width x velocity) effusion rate (0.6 m3/s) showed excellent agreement. In addition, the comparison between FLIR-derived effusion rates and satellite (AVHRR) derived values showed a good correlation (R = 0.9). (II) Santiaguito: Satellite-derived eruption rates for a lava dome A time series of 21 Landsat ETM+ and TM images acquired during 1986-2003, were used to calculate eruption rates at Santiaguito dome (Guatemala) to yield a time-averaged effusion rate of 0.4 m3/s. Field-based flow dimension and velocity measurements during 1987 and 2000-03 yielded a values of 0.6±0.3 and 0.5±0.2 m3/s which compared with an ETM+ derived values of 0.7±0.1 and 0.5±0.1 m3/s, respectively

  10. Numerical model of crater lake eruptions

    NASA Astrophysics Data System (ADS)

    Morrissey, M.; Gisler, G.; Weaver, R.; Gittings, M.

    2010-12-01

    We present results from a numerical investigation of subaqueous eruptions involving superheated steam released through a lake mimicking the volcanic setting at Mt. Ruapehu. The simulations were conducted using an adaptive mesh, multi-material, hydrodynamics code with thermal conduction SAGE, (Simple Adaptive Grid Eulerian). Parameters investigated include eruption pressure, lake level and mass of superheated vapor. The simulations produced a spectrum of eruption styles from vapor cavities to radial jets that resulted in hazards that ranged from small-scale waves to high amplitude surges that reached and cascaded over the edge of the crater rim. There was an overall tendency for lake surface activity to increase (including wave amplitude) with increasing mass of superheated vapor and eruption pressure. Surface waves were induced by the formation and collapse of a gas cavity. The collapse of the cavity is considered to play a major role in the characteristic features observed during a subaqueous eruption. The additional mass of superheated vapor produced a larger cavity that displaced a larger area of the lake surface resulting in fast moving surges upon the collapse of the cavity. High lake levels (>90 m) appear to suppress the development of explosive jetting activity when eruption pressures are <10 MPa. At very large eruption pressures (>10 MPa), vertical jets and radial ejections of steam and water can occur in water depths >90 m. Less explosive eruption styles can produce hazardous events such as lahars by the outward movement of surface waves over the crater rim.

  11. Redistribution of static stress, induced by the 2002-2003 Etna eruption, triggers seismic activity: a viscoelastic numerical model

    NASA Astrophysics Data System (ADS)

    Pulvirenti, Fabio; Aloisi, Marco

    2014-05-01

    The principal aim of this study is the investigation of the relationship between the push of the dike-forming magmatic intrusions and the faulting process in terms of earthquakes generation. A complete time-dependent 3D finite element model for the 2002-2003 eruption at Mount Etna is presented. The model, which takes into account the topography, medium heterogeneities and principal fault systems, is developed in a viscoelastic environment by a generalized Maxwell rheological description. To investigate where fault slips were encouraged or not and consequently how earthquakes may have been triggered, we look at the Coulomb stress changes induced by the magma uprising, during the co-intrusive and post-intrusive periods, focusing on the area of Pernicana Fault and S. Venerina Fault, which have been reactivated during the studied eruption. The temporal variation of the Coulomb stress changes allows to know the time of maximum stress transfer and then to infer the areas where there is an higher probability of earthquake occurrence. Results show positive stress changes for Pernicana Fault in accordance to the time, location and depth of the 27th October 2002 Pernicana earthquakes (Mmax = 3.8). Moreover, the amount of Coulomb stress changes on S. Venerina Fault, as induced by dike-forming intrusions, is not enough to trigger the 29th October Santa Venerina earthquakes (Mmax = 4.4), two days after the start of the eruption. The necessary Coulomb stress changes value to trigger the 29th S. Venerina Fault earthquakes is instead reached if we consider them as aftershocks of the 27th October Pernicana biggest earthquake. Acknowledgments This work was supported by MED-SUV Project.

  12. NUMERICAL INVESTIGATION OF A CORONAL MASS EJECTION FROM AN ANEMONE ACTIVE REGION: RECONNECTION AND DEFLECTION OF THE 2005 AUGUST 22 ERUPTION

    SciTech Connect

    Lugaz, N.; Shibata, K.; Downs, C.; Roussev, I. I.; Asai, A.; Gombosi, T. I.

    2011-09-10

    We present a numerical investigation of the coronal evolution of a coronal mass ejection (CME) on 2005 August 22 using a three-dimensional thermodynamic magnetohydrodynamic model, the space weather modeling framework. The source region of the eruption was anemone active region (AR) 10798, which emerged inside a coronal hole. We validate our modeled corona by producing synthetic extreme-ultraviolet (EUV) images, which we compare to EIT images. We initiate the CME with an out-of-equilibrium flux rope with an orientation and chirality chosen in agreement with observations of an H{alpha} filament. During the eruption, one footpoint of the flux rope reconnects with streamer magnetic field lines and with open field lines from the adjacent coronal hole. It yields an eruption which has a mix of closed and open twisted field lines due to interchange reconnection and only one footpoint line-tied to the source region. Even with the large-scale reconnection, we find no evidence of strong rotation of the CME as it propagates. We study the CME deflection and find that the effect of the Lorentz force is a deflection of the CME by about 3{sup 0} R{sup -1}{sub sun} toward the east during the first 30 minutes of the propagation. We also produce coronagraphic and EUV images of the CME, which we compare with real images, identifying a dimming region associated with the reconnection process. We discuss the implication of our results for the arrival at Earth of CMEs originating from the limb and for models to explain the presence of open field lines in magnetic clouds.

  13. Numerical Investigation of a Coronal Mass Ejection from an Anemone Active Region: Reconnection and Deflection of the 2005 August 22 Eruption

    NASA Astrophysics Data System (ADS)

    Lugaz, N.; Downs, C.; Shibata, K.; Roussev, I. I.; Asai, A.; Gombosi, T. I.

    2011-09-01

    We present a numerical investigation of the coronal evolution of a coronal mass ejection (CME) on 2005 August 22 using a three-dimensional thermodynamic magnetohydrodynamic model, the space weather modeling framework. The source region of the eruption was anemone active region (AR) 10798, which emerged inside a coronal hole. We validate our modeled corona by producing synthetic extreme-ultraviolet (EUV) images, which we compare to EIT images. We initiate the CME with an out-of-equilibrium flux rope with an orientation and chirality chosen in agreement with observations of an Hα filament. During the eruption, one footpoint of the flux rope reconnects with streamer magnetic field lines and with open field lines from the adjacent coronal hole. It yields an eruption which has a mix of closed and open twisted field lines due to interchange reconnection and only one footpoint line-tied to the source region. Even with the large-scale reconnection, we find no evidence of strong rotation of the CME as it propagates. We study the CME deflection and find that the effect of the Lorentz force is a deflection of the CME by about 3° R -1 sun toward the east during the first 30 minutes of the propagation. We also produce coronagraphic and EUV images of the CME, which we compare with real images, identifying a dimming region associated with the reconnection process. We discuss the implication of our results for the arrival at Earth of CMEs originating from the limb and for models to explain the presence of open field lines in magnetic clouds.

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

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  15. Long-term cycles in Large Igneous Province (LIP) eruptions and fossil diversity may be related to periodic mantle plume activity

    NASA Astrophysics Data System (ADS)

    Rampino, M. R.; Prokoph, A.

    2013-12-01

    Wavelet analysis shows evidence for an approximately 62 Myr cycle in the eruptions of Large Igneous Provinces (LIPs) over the last 540 Myr. This agrees with a cycle of 62×3 Myr seen in fossil biodiversity over the same interval. A similar cycle (about 56-62 Myr) has been reported in data related to continental-scale fluctuations of sedimentation, most likely resulting from changes in climate, sea level and tectonics. A longer about 140 Myr cycle is also detected in the LIP eruption data, matching a similar cycle seen in fossil diversity and in global climate. Both the LIP and fossil diversity data sets show a shorter approximately 28-35 Myr period, especially during the last 135 Myr. Cross-spectral wavelet analysis of the LIP occurrences against the marine diversity record shows that almost all cross-variability in the two data sets is concentrated in the 28 to 35 Myr, 62 to 65 Myr and around 140 Myr wavelength bands, showing a sharp change from dominant 62 Myr to 32 Myr cyclicity since the Early Cretaceous. The phase differences for the cycles indicate an inverse LIP-diversity relationship at these wavebands. The LIP eruptions commonly mark the initiation of hotspots, presumably created by upwelling mantle plumes. The agreement among these periodicities suggests that long-term global cycles of biodiversity, sea level, climate and sedimentation are partly driven by periodic or quasi-periodic fluctuations in mantle plume activity. This conclusion is bolstered by the close temporal correlation of several LIPs with times of mass extinction and climatic crises indicated by ocean anoxic events.

  16. Managing public and media response to a reawakening volcano: lessons from the 2004 eruptive activity of Mount St. Helens: Chapter 23 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Frenzen, Peter M.; Matarrese, Michael T.

    2008-01-01

    Volcanic eruptions and other infrequent, large-scale natural disturbances pose challenges and opportunities for public-land managers. In the days and weeks preceding an eruption, there can be considerable uncertainty surrounding the magnitude and areal extent of eruptive effects. At the same time, public and media interest in viewing developing events is high and concern for public safety on the part of local land managers and public safety officials is elevated. Land managers and collaborating Federal, State, and local officials must decide whether evacuations or restrictions to public access are necessary, the appropriate level of advance preparation, and how best to coordinate between overlapping jurisdictions. In the absence of a formal Federal or State emergency declaration, there is generally no identified source of supplemental funding for emergency-response preparation or managing extraordinary public and media response to developing events. In this chapter, we examine responses to escalating events that preceded the 2004 Mount St. Helens eruption and changes in public perception during the extended period of the largely nonexplosive, dome-building eruption that followed. Lessons learned include the importance of maintaining up-to-date emergency-response plans, cultivating close working relationships with collaborating agencies, and utilizing an organized response framework that incorporates clearly defined roles and responsibilities and effective communication strategies.

  17. Impact of tephra falls on Andean communities: The influences of eruption size and weather conditions during the 1999-2001 activity of Tungurahua volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Le Pennec, Jean-Luc; Ruiz, Gorki A.; Ramón, Patricio; Palacios, Enrique; Mothes, Patricia; Yepes, Hugo

    2012-03-01

    Repeated ash fall events have occurred during the 1999-ongoing eruption of Tungurahua volcano, Ecuador, notably during the late 1999 and August 2001 eruptive phases. While the eruptive styles were similar, these two phases had different impacts on nearby rural and urban Andean populations: ash falls in late 1999 had limited effects on human health and farming, whereas the 2001 phase resulted in medical problems, death of animals in livestock, and damages to houses and crops. Here we investigate the origin of this difference by estimating the size of the August 2001 event (VEI, magnitude, intensity), and by comparing monitoring information of the 1999 and 2001 phases (duration, explosion rate, column height, SO2 output rate). The results show that both phases ranked at VEI 3, although the longer 1999 phase was likely larger than the 2001 phase. Mass magnitude (M) and intensity (I) indexes calculated for the 2001 phase reach M ≈ 2.7 and I ≈ 6.5 when based on ash fall layer data, but increase to M ≈ 3.2 and I ≈ 7.0 when ballistic products are included. We investigated the influence of rain fall and wind flow regimes on ash dispersion, sedimentation and remobilization. The analysis indicates that the harmful effect of the 2001 phase resulted from unfavorable conditions that combined volcanological and seasonal origins, including: a) a low elevation of the ash plume above rural regions owed to a usually bent-over column, b) ash sedimentation in a narrow area west of the volcano under sub-steady wind directions, c) anticipated ash settling by frequent rain flushing of low intensity, and d) formation of a wet cohesive ash coating on buildings and harvests. Conversely, the stronger 1999 phase injected a large amount of ash at higher elevation in the dry season; the ash was widely disseminated across the whole Ecuadorian territory and beyond, and was frequently removed by rain and winds. In summary, our study illustrates the influences of eruption size and weather

  18. An Eruption on Io

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The first images returned to Earth by New Horizons during its close encounter with Jupiter feature the Galilean moon Io, snapped with the Long Range Reconnaissance Imager (LORRI) at 0840 UTC on February 26, while the moon was 2.5 million miles (4 million kilometers) from the spacecraft.

    Io is intensely heated by its tidal interaction with Jupiter and is thus extremely volcanically active. That activity is evident in these images, which reveal an enormous dust plume, more than 150 miles high, erupting from the volcano Tvashtar. The plume appears as an umbrella-shaped feature of the edge of Io's disk in the 11 o'clock position in the right image, which is a long-exposure (20-millisecond) frame designed specifically to look for plumes like this. The bright spots at 2 o'clock are high mountains catching the setting sun; beyond them the night side of Io can be seen, faintly illuminated by light reflected from Jupiter itself.

    The left image is a shorter exposure -- 3 milliseconds -- designed to look at surface features. In this frame, the Tvashtar volcano shows as a dark spot, also at 11 o'clock, surrounded by a large dark ring, where an area larger than Texas has been covered by fallout from the giant eruption.

    This is the clearest view yet of a plume from Tvashtar, one of Io's most active volcanoes. Ground-based telescopes and the Galileo Jupiter orbiter first spotted volcanic heat radiation from Tvashtar in November 1999, and the Cassini spacecraft saw a large plume when it flew past Jupiter in December 2000. The Keck telescope in Hawaii picked up renewed heat radiation from Tvashtar in spring 2006, and just two weeks ago the Hubble Space Telescope saw the Tvashtar plume in ultraviolet images designed to support the New Horizons flyby.

    Most of those images will be stored onboard the spacecraft for downlink to Earth in March and April.

  19. C3-class Solar Flare Eruption

    NASA Video Gallery

    Just as sunspot 1105 was turning away from Earth on Sept. 8, the active region erupted, producing a C3-class solar flare (peak @ 2330 UT) and a fantastic prominence. This is a three color closeup o...

  20. Seismic activity that accompanied the effusive and explosive eruptions during the 2004-2005 period at Volcán de Colima, Mexico

    NASA Astrophysics Data System (ADS)

    Arámbula-Mendoza, R.; Lesage, P.; Valdés-González, C.; Varley, N. R.; Reyes-Dávila, G.; Navarro, C.

    2011-08-01

    Volcán de Colima is considered the most active in Mexico. A period of large eruptive activity occurred in 2004-2005. It began as a swarm of long-period events (LPs) in late September 2004, indicating the onset of growth of a new lava dome in its crater. Subsequently, avalanches of incandescent material and pyroclastic flows during a period of approximately 2 months occurred. Then, the activity became more explosive with moderate explosions. Finally, swarms of LPs accompanied the magma ascent and extrusion of small domes and vulcanian explosions with pyroclastic flows in 2005. This eruptive period was investigated with a continuous seismic signal study, cross-correlation of LPs and autoregressive analysis of monochromatic LPs. For the vast majority of the explosions, an increase in the rate of seismic energy was observed with the Seismic Spectral Energy Measurement (SSEM) from 1 to 3 Hz, before each explosive event. This increase in energy is proportional to the increase in the rate of LPs, probably as a result of an increase in the emission rate. Applying the material failure forecasting method (FFM) and using SSEM inverse of parameter, the time of the explosions is estimated as the time when the adjusted line reaches the null value. We observe a systematic delay of a few hours between the real time of occurrence of the explosions and the estimated time. This suggests that more complex processes than pure damaging of the plug occur before the explosions. The swarms associated with the large explosions include a large proportion of LPs with similar waveforms. They form a dozen of families which stay during the whole period of activity and which indicate repetitive sources. Some of the families are active only before the explosions and could therefore be used as early warning. Monochromatic LP events occurred during this period, some of them just some hours before an explosion. However, no clear relationship between their occurrence and the explosions could be found.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  2. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania. I. New magma composition during the 2007-2008 explosive eruptions

    NASA Astrophysics Data System (ADS)

    Keller, Jörg; Klaudius, Jurgis; Kervyn, Matthieu; Ernst, Gerald G. J.; Mattsson, Hannes B.

    2010-10-01

    With a paroxysmal ash eruption on 4 September 2007 and the highly explosive activity continuing in 2008, Oldoinyo Lengai (OL) has dramatically changed its behavior, crater morphology, and magma composition after 25 years of quiet extrusion of fluid natrocarbonatite lava. This explosive activity resembles the explosive phases of 1917, 1940-1941, and 1966-1967, which were characterized by mixed ashes with dominantly nephelinitic and natrocarbonatitic components. Ash and lapilli from the 2007-2008 explosive phase were collected on the slopes of OL as well as on the active cinder cone, which now occupies the entire north crater having buried completely all earlier natrocarbonatite features. The lapilli and ash samples comprise nepheline, wollastonite, combeite, Na-åkermanite, Ti-andradite, resorbed pyroxene and Fe-Ti oxides, and a Na-Ca carbonate phase with high but varying phosphorus contents which is similar, but not identical, to the common gregoryite phenocrysts in natrocarbonatite. Lapilli from the active cone best characterize the erupted material as carbonated combeite-wollastonite-melilite nephelinite. The juvenile components represent a fundamentally new magma composition for OL, containing 25-30 wt.% SiO2, with 7-11 wt.% CO2, high alkalies (Na2O 15-19%, K2O 4-5%), and trace-element signatures reminiscent of natrocarbonatite enrichments. These data define an intermediate composition between natrocarbonatite and nephelinite, with about one third natrocarbonatite and two thirds nephelinite component. The data are consistent with a model in which the carbonated silicate magma has evolved from the common combeite-wollastonite nephelinite (CWN) of OL by enrichment of CO2 and alkalies and is close to the liquid immiscible separation of natrocarbonatite from carbonated nephelinite. Material ejected in April/May 2008 indicates reversion to a more common CWN composition.

  3. Dome forming eruptions: a global hazards database

    NASA Astrophysics Data System (ADS)

    Ogburn, S. E.; Loughlin, S.; Calder, E. S.; Ortiz, N.

    2009-12-01

    The analysis of global datasets of historical eruptions is a powerful tool for decision-making as well as for scientific discovery. Lava dome forming eruptions are common throughout the world, can extend for significant periods of time and have many associated hazards, thus providing a rich source of data to mine. A database on dome forming eruptions is under development with the view to aiding comparative studies, providing scientists with valuable data for analysis, and enabling advances in modeling of associated hazards. For new eruptive episodes in particular, and in the absence of monitoring data or a knowledge of a volcano’s eruptive history, global analysis can provide a method of understanding what might be expected based on similar eruptions in the past. Important scientific information has already been gleaned from disparate collections of dome-forming eruption hazard information, such as variation in the mobility of different types of pyroclastic flows, magma ascent and extrusion dynamics, and mechanisms of lava dome collapse. Further, modeling (both empirically-based and geophysically-based) of volcanic phenomena requires extensive data for development, calibration and validation. This study investigates the relationship between large explosive eruptions (VEI ≥ 4) and lava dome-growth from 1000 CE to present by development of a world-wide database of all relevant information, including dome growth duration, pauses between episodes of dome growth, and extrusion rates. Data sources include the database of volcanic activity maintained by the Smithsonian Institute (Global Volcanism Program) and all relevant published review papers, research papers and reports. For example, nearly all dome-forming eruptions have been associated with some level of explosive activity. Most explosions are vulcanian with eruption plumes reaching less than 15 km, and with a Volcanic Explosivity Index (VEI) <3. However large Plinian explosions with a VEI ≥ 4 can also occur

  4. Timing signatures of large scale solar eruptions

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Hock-Mysliwiec, Rachel; Henry, Timothy; Kirk, Michael S.

    2016-05-01

    We examine the timing signatures of large solar eruptions resulting in flares, CMEs and Solar Energetic Particle events. We probe solar active regions from the chromosphere through the corona, using data from space and ground-based observations, including ISOON, SDO, GONG, and GOES. Our studies include a number of flares and CMEs of mostly the M- and X-strengths as categorized by GOES. We find that the chromospheric signatures of these large eruptions occur 5-30 minutes in advance of coronal high temperature signatures. These timing measurements are then used as inputs to models and reconstruct the eruptive nature of these systems, and explore their utility in forecasts.

  5. Overview Of Mount St. Helens Volcanic Eruption

    NASA Astrophysics Data System (ADS)

    Tilling, Robert I.

    Dormant since 1857, Mount St. Helens Volcano in southwestern Washington stirred from its repose to erupt on March 27, 1980, following a week of premonitory earthquake activity. The eruption was the first in the conterminous United States since the 1914-1921 activity of Lassen Peak, California. The eruptive activity through May 17 was intermittent and relatively mild, but the accompanying seismic activity remained intense. On May 18, a catastrophic eruption, triggered by a magnitude 5.0 earthquake, produced a massive landslide/debris avalanche, a devastating lateral "blast," pyroclastic flows, mudflows, and an ash column that rose more than 20 km into the stratosphere. Winds carried the ash easterly, and more than 7 cm of ash was deposited locally in parts of eastern Washington. The landslide/debris avalanche and associated mudflows caused flooding of the Toutle and Cowlitz River valleys, which carried sediment as far as the confluence with the Columbia, where it choked off the channel to navigation. Smaller but significant explosive eruptions followed in May, June, July, August, and October, 1980, with lava domes being extruded in the crater following the June, August, and October eruptions. Subsequently in December 1980 and February 1981, lava domes were extruded without significant preceding explosive activity. Except for the latter two, each dome was partly or wholly destroyed by succeeding explosive events. Scientists expect similar activity to continue for months or years--possibly even decades. The Mount St. Helens eruptions severely tested the ability of scientists to respond swiftly and effectively in assisting public officials during a geologic disaster. At the same time, they shall continue to provide an unprecedented opportunity for the systematic investigation of volcanic phenomena, and hopefully, the insight to meet possible future eruptions there and elsewhere in the Cascade Range with equal success.

  6. Volatile concentrations in variably vesicular pyroclasts from the Rotongaio ash (181 AD Taupo eruption): did shallow magma degassing trigger exceptionally violent phreatomagmatic activity?

    NASA Astrophysics Data System (ADS)

    Tuffen, Hugh; Houghton, Bruce F.; Dingwellp, Donald B.; Pinkerton, Harry

    2010-05-01

    Measurement of dissolved volatile concentrations in pyroclasts has formed the basis of our understanding of the links between magma degassing and the explosivity of silicic eruptions[1]. To date these studies have focussed exclusively on the densest pyroclastic obsidians, which comprise on a tiny proportion of the erupted products, in order to bypass the difficulty of analysing vesicular material. As a consequence, crucial information is missing about how degassing in the densest clasts relates to the behaviour of the bulk of the magma volume. To overcome this shortcoming, the volatile content of variably vesicular pyroclasts from the Rotongaio ash has been analysed using both micro-analytical (SIMS, synchrotron FTIR) and bulk techniques (TGA-MS). The Rotongaio ash was an exceptionally violent phase of phreatomagmatic activity during the 181 AD rhyolitic eruption of Taupo (New Zealand), the most powerful worldwide in the last 5000 years. The Rotongaio phase involved opening of new vents beneath Lake Taupo and the ash is characterised by a wide range of clast vesicularities (<10 to ~80 % by volume). Volatile measurement was challenging due to the high bubble number densities and small clast sizes. The mismatch between the water content of matrix glasses measured using bulk and micro-analytical techniques reflects pervasive post-eruption hydration of vesicle walls, which is most problematic at high vesicularities. Micron-scale maps of water concentration variations around vesicles in 30-50 vol % vesicular samples were acquired using SIMS. They indicate strong hydration within ~5 microns of vesicle walls, with pockets of unhydrated glass remaining in the thickest septa. Analysis of these unhydrated domains allowed robust measurement of water contents in pyroclasts ranging from ~1 to >50 vol % vesicles. Matrix glasses had largely degassed (0.19-0.49 wt % H2O, compared with an initial concentration in melt inclusions of ~3.6 wt %). The water contents measured using SIMS

  7. The 2008 eruption of Chaitén volcano, Southern Chile: a tectonically controlled eruption?

    NASA Astrophysics Data System (ADS)

    Lara, L. E.; Pallister, J. S.; Ewert, J. W.

    2008-12-01

    initially high plumes and only limited column collapse argue for a relatively strong and narrow conduit and vent structure during the early explosive eruptions. However, the sustained high-rate and large-volume lava eruption (now 4 months in duration) accompanied by relatively low explosivity and low SO2 emissions argue against a purely gas-driven eruptive process. We propose a model for magmatism at Chaitén, in which the timing and compositions of eruptions are controlled by tectonism along the Liquiñe-Ofqui Fault Zone (LOFZ), a 1200 km long structure that is part of a dextral transpressional arc domain. In this model, silicic magmas are trapped and stored at deep levels of the crust (10 km?) during periods of upper crustal localized compression, and eruptions are triggered by tectonic shifts that open tear faults and promote magma transport to the surface. Consistent with seismicity along the LOFZ and subsidiary branches before and during the eruption and with new InSAR data that indicate fault-controlled syn-eruptive deformation, we suggest that such a process triggered the 2008 eruption and that re-establishment of compression, following the initial Plinian phase, has sustained an anomalously high-rate of lava production for the past four months. In turn, fluid flow along the fault-fracture network enhances seismic activity, which is still recorded. The two- way coupling between tectonics and volcanism provides a challenging conceptual framework for hazards assessment in Southern Andes.

  8. The 2010 Eruption of Merapi Volcano, Java, Indonesia: Petrological Insights into Magma Dynamics and Eruptive Behaviour

    NASA Astrophysics Data System (ADS)

    Gertisser, R.; Handley, H.; Preece, K.; Reagan, M.; Berlo, K.; Barclay, J.; Herd, R.

    2012-04-01

    The violent eruption of Merapi volcano (Central Java) that started on 26 October 2010 was the volcano's largest since 1872 and the deadliest event since 1930. Before 2010, Merapi's more recent (historical) eruptive activity was repeatedly characterised by periods of slow lava dome extrusion punctuated by gravitational dome failures, generating small-volume pyroclastic density currents (PDCs) with runout distances of typically less than 10 km. The unforeseen, large-magnitude events in 2010 were unusual in many respects: (1) the eruption was short-lived and started with an explosive phase that was not preceded by a lava dome at the surface; (2) between 31 October and 4 November, a lava dome appeared and grew rapidly within the summit crater, exceeding growth rates observed at the peak of the penultimate eruption in 2006 by a factor of ~ 22; (3) during the most vigorous eruptive phase on 5 November, at least one PDC travelled more than 15 km (more than twice the distance of the largest flows in 2006) beyond the summit along the Gendol river valley, causing widespread devastation on Merapi's south flank; (4) in a late phase of the eruption, pumice-rich PDCs were produced, forming a thin veneer on top of the deposits of the largest PDCs from 5 November; (5) ash emissions from sustained eruption columns resulted in ash fall tens of kilometres from the volcano, affecting, amongst other areas, the volcano's western slopes and the city of Yogyakarta ~ 25 km to the south; and (6) the total deposited volume in 2010, based on provisional estimates, may have been ~ 10 times higher than that of other recent eruptions. Here we report and present new geochemical, Sr-Nd-O isotope and U-series data for the volcanic products (lava dome fragments, magmatic inclusions, scoria, pumice and ash) from various stages of the 2010 eruption of Merapi. These data are discussed in the context of other recent to historical, typically less explosive, dome-forming eruptions to elucidate the driving

  9. Gas-driven eruptions at Mount Ruapehu, New Zealand: towards a coherent model of eruption

    NASA Astrophysics Data System (ADS)

    Kilgour, G. N.; Mader, H. M.; Mangan, M.; Blundy, J.

    2010-12-01

    Mt. Ruapehu is an andesitic cone volcano situated at the southern end of the Taupo Volcanic Zone. The summit plateau at Ruapehu consists of three craters (South, Central and North). Historical activity has consisted of frequent small phreatic and phreatomagmatic eruptions from South Crater. The active vents of South Crater are submerged beneath Crater Lake - a warm, acidic lake. The most recent eruption at Ruapehu occurred on 25th September, 2007 that generated a moderate steam column to about 4.5 km above Crater Lake, and a directed ballistic and surge deposit of coarse blocks and ash to the north of Crater Lake. It also initiated lahars in two catchments. The eruption occurred during the ski season and it resulted in the temporary closure of the three ski fields. Seismicity for the main eruption lasted for about 4 minutes and included an explosive phase which lasted for less than 1 minute and a post-explosion phase which probably indicated resonance in the conduit together with signals generated from lahars and vent stabilisation. Preceding seismicity occurred ~ 10 min before the eruption. The 2007 eruption appears strikingly similar to phreatic/phreatomagmatic eruptions of 1969 and 1975. In those eruptions, limited precursory seismicity was recorded, the bulk of the erupted deposits were accidental lithics, including lake sediments and older lavas, and only a small amount of juvenile material was erupted (~ 5%). It is likely that all three eruptions were driven by magmatic gases, either stored and pressurised beneath a hydrothermal seal, or rapidly exsolved during a gas release event. This poster outlines the plan that we will use to model this common type of eruption at Ruapehu. We will analyse the volatile content of phenocryst-hosted melt inclusions to determine the degassing depth of historic eruptions. This will allow us to identify where the magmas have been or are degassing beneath Crater Lake. Analogue modelling of gas and fluid flow through a visco

  10. Thermal signature, eruption style, and eruption evolution at Pele and Pillan on Io

    USGS Publications Warehouse

    Davies, A.G.; Keszthelyi, L.P.; Williams, D.A.; Phillips, C.B.; McEwen, A.S.; Lopes, R.M.C.; Smythe, W.D.; Kamp, L.W.; Soderblom, L.A.; Carlson, R.W.

    2001-01-01

    The Galileo spacecraft has been periodically monitoring volcanic activity on Io since June 1996, making it possible to chart the evolution of individual eruptions. We present results of coanalysis of Near-Infrared Mapping Spectrometer (NIMS) and solid-state imaging (SSI) data of eruptions at Pele and Pillan, especially from a particularly illuminating data set consisting of mutually constraining, near-simultaneous NIMS and SSI observations obtained during orbit C9 in June 1997. The observed thermal signature from each hot spot, and the way in which the thermal signature changes with time, tightly constrains the possible styles of eruption. Pele and Pillan have very different eruption styles. From September 1996 through May 1999, Pele demonstrates an almost constant total thermal output, with thermal emission spectra indicative of a long-lived, active lava lake. The NIMS Pillan data exhibit the thermal signature of a "Pillanian" eruption style, a large, vigorous eruption with associated open channel, or sheet flows, producing an extensive flow field by orbit C10 in September 1997. The high mass eruption rate, high liquidus temperature (at least 1870 K) eruption at Pillan is the best candidate so far for an active ultramafic (magnesium-rich, "komatiitic") flow on Io, a style of eruption never before witnessed. The thermal output per unit area from Pillan is, however, consistent with the emplacement of large, open-channel flows. Magma temperature at Pele is ???1600 K. If the magma temperature is 1600 K, it suggests a komatiitic-basalt composition. The power output from Pele is indicative of a magma volumetric eruption rate of ???250 to 340 m3 s-1. Although the Pele lava lake is considerably larger than its terrestrial counterparts, the power and mass fluxes per unit area are similar to active terrestrial lava lakes. Copyright 2001 by the American Geophysical Union.

  11. Volcanic Eruptions and Climate

    NASA Astrophysics Data System (ADS)

    Robock, A.

    2012-12-01

    Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of these aerosol clouds produce responses in the climate system. Observations and numerical models of the climate system show that volcanic eruptions produce global cooling and were the dominant natural cause of climate change for the past millennium, on timescales from annual to century. Major tropical eruptions produce winter warming of Northern Hemisphere continents for one or two years, while high latitude eruptions in the Northern Hemisphere weaken the Asian and African summer monsoon. The Toba supereruption 74,000 years ago caused very large climate changes, affecting human evolution. However, the effects did not last long enough to produce widespread glaciation. An episode of four large decadally-spaced eruptions at the end of the 13th century C.E. started the Little Ice Age. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade had a small effect on global temperature trends. The June 13, 2011 Nabro eruption in Eritrea produced the largest stratospheric aerosol cloud since Pinatubo, and the most of the sulfur entered the stratosphere not by direct injection, but by slow lofting in the Asian summer monsoon circulation. Volcanic eruptions warn us that while stratospheric geoengineering could cool the surface, reducing ice melt and sea level rise, producing pretty sunsets, and increasing the CO2 sink, it could also reduce summer monsoon precipitation, destroy ozone, allowing more harmful UV at the surface, produce rapid warming when stopped, make the sky white, reduce solar power, perturb the ecology with more diffuse radiation, damage airplanes flying in the stratosphere, degrade astronomical observations, affect remote sensing, and affect

  12. History of earthquakes and vertical ground movement in Campi Flegrei caldera, Southern Italy: comparison of precursory events to the A.D. 1538 eruption of Monte Nuovo and of activity since 1968

    USGS Publications Warehouse

    Dvorak, J.J.; Gasparini, P.

    1991-01-01

    The record of felt earthquakes around Naples Bay in southern Italy is probably complete since the mid-15th century. According to this record, intense earthquake swarms originating beneath Campi Flegrei, an explosive caldera located along the north coast of Naples Bay, have occurred only twice: (1) before the only historical eruption in Campi Flegrei in 1538; and (2) from mid-1983 to December 1984. Earthquake activity during the earlier period, which began at least a few years, and possibly as many as 30 years, before the 1538 eruption, damaged many buildings in the city of Pozzuoli, located near the center of Campi Flegrei. Minor seismic activity, which consisted of only a few felt earthquakes, occurred from 1970 to 1971. The second period of intense earthquake swarms lasted from mid-1983 to 1984, again damaging many buildings in Pozzuoli. Two periods of uplift along the shoreline within Campi Flegrei have also been noted since the mid-15th century: (1) during the few decades before the 1538 eruption; and (2) as two distinct episodes since 1968. Uplift of a few meters probably occurred a few decades before the 1538 eruption; uplift of as much as 3.0 m has occurred in Pozzuoli since 1968. These similarities strongly suggest that, for the first time in 440 years, the same process that caused intense local earthquake swarms and uplift in the early 1500's and led to an eruption in 1538, has again occurred beneath Campi Flegrei. Though no major seismicity or uplift has occurred since December 1984, because of the large amount of extensional strain accumulated during the past two decades, if a third episode of seismicity and rapid uplift occurs, it may lead to an eruption within several months after the resumption of activity. ?? 1991.

  13. Morphometrical and geochronological constraints on the youngest eruptive activity in East-Central Europe at the Ciomadul (Csomád) lava dome complex, East Carpathians

    NASA Astrophysics Data System (ADS)

    Karátson, Dávid; Telbisz, Tamás; Harangi, Szabolcs; Magyari, Enikő; Dunkl, István; Kiss, Balázs; Jánosi, Csaba; Veres, Daniel; Braun, Mihály; Fodor, Emőke; Biró, Tamás; Kósik, Szabolcs; von Eynatten, Hilmar; Lin, Ding

    2013-04-01

    The timing of Late Pleistocene volcanic activity of the Ciomadul (Csomád) dacitic lava dome complex, site of the youngest eruptions in the Carpathians, has been constrained by morphometric analysis and radiometric chronology. Peléan domes and asymmetric domes/coulées built up the volcano, including the central edifice that hosts the youngest twin craters of Mohoş (Mohos) peat bog and lake St. Ana (Szent Anna). A comparative digital elevation model (DEM)-based morphometric analysis of lava domes (29 worldwide examples including 5 domes from Ciomadul) shows that it is the mean slope of the upper dome flank that correlates best with age. Although the logarithmic relationship is only moderately strong (R = 0.80), slope characteristics of the Ciomadul domes fit to those of 10-100 ka old domes. These young ages contradict the previous K/Ar dates giving as old as 1 Ma ages on a number of domes, but are supported by ongoing U-Pb and (U-Th)/He zircon dating. The latter methods constrain the whole volcanic activity to the past 250 ka and the emplacement of most lava domes within the period of 150-100 ka. The volcanism at Ciomadul produced alternating effusive and explosive eruptions including lava dome collapses and successive crater formations. The latest, possibly subplinian explosive event formed the well-preserved St. Ana crater. Radiocarbon dating of organic remains from a sediment core that reached 11 m into the lacustrine infill of St. Ana suggests that the crater was formed prior to 26,000 years BP.

  14. Conduit Wall Failure as a Trigger for Transition From Strombolian to Phreatomagmatic Explosive Activity in the Cova de Paúl Crater Eruption on Santo Antão, Cape Verde Islands

    NASA Astrophysics Data System (ADS)

    Tarff, R. W.; Day, S. J.

    2011-12-01

    Episodes of hazardous phreatomagmatic explosive activity, including Surtseyan activity, occur within otherwise less dangerous effusive to mildly explosive magmatic eruptions at high-elevation vents on many oceanic island volcanoes. The water driving these explosions is sourced from freshwater aquifers within the volcanic edifices. Understanding volcanic and geophysical precursors to, and mechanisms of, the (frequently abrupt) transitions to explosive activity is required as a basis for effective warning and mitigation of the resulting hazards. Here we describe near-vent deposits around the large Cova de Paúl crater on the island of Santo Antão, Cape Verde Islands, which provide some insights into a transition from mild magmatic to violently explosive phreatomagmatic activity in one such eruption. This pre-historic but well-preserved crater formed in a single eruption that produced extensive low-temperature, lithic-rich phreatomagmatic pyroclastic flows and surge deposits; these are interbedded in proximal outcrops with airfall breccia and ash beds containing varying proportions of lithic and juvenile clasts, pointing to a series of climactic explosions within an extended period of milder explosive activity of broadly Surtseyan type. Prior to the transition to phreatomagmatic activity, the eruption had been characterized by mild Strombolian activity that produced scoria and spatter deposits of broadly tephritic composition. The Strombolian deposits contain a distinct population of strongly banded, low-vesicularity angular clasts with strongly prolate vesicles and a notably glassy appearance. These became markedly larger and more abundant just below the transition to the phreatomagmatic deposits. Comparisons of these clasts with the Strombolian scoria suggest that they are fragments of flow-banded chilled margins from the walls of the eruptive conduit. Thermal shattering of these margins to produce the angular glassy clasts may record the onset of groundwater flow

  15. Solar Prominence Eruption

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.

    1998-01-01

    The prominence that erupts in a prominence eruption is a magnetic structure in the chromosphere and corona. It is visible in chromospheric images by virtue of chromospheric-temperature plasma suspended in the magnetic field, and belongs to that large class of magnetic structures appropriately called filaments because of their characteristic sinewy sigmoidal form. Hence, the term "filament eruption" is used interchangeably with the term "prominence eruption". The magnetic field holding a filament is prone to undergo explosive changes in configuration. In these upheavals, because the filament material is compelled by its high conductivity to ride with the magnetic field that threads it, this material is a visible tracer of the field motion. The part of the magnetic explosion displayed by the entrained filament material is the phenomenon known as a filament eruption, the topic of this article. This article begins with a description of basic observed characteristics of filament eruptions, with attention to the magnetic fields, flares, and coronal mass ejections in which erupting filaments are embedded. The present understanding of these characteristics in terms of the form and action of the magnetic field is then laid out by means of a rudimentary three-dimensional model of the field. The article ends with basic questions that this picture leaves unresolved and with remarks on the observations needed to probe these questions.

  16. Sympathetic Solar Filament Eruptions

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Liu, Ying D.; Zimovets, Ivan; Hu, Huidong; Dai, Xinghua; Yang, Zhongwei

    2016-08-01

    The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic filament eruptions. We investigate the relations between the different filaments involved in the eruption. A surge-like small-scale filament motion is confirmed as the trigger that initiated the erupting filament with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting filament moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filament that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for F2 rapid acceleration and have some relation with the largest solar storm. The comparison between the successful and failed filament eruptions suggests that the confining magnetic field plays an important role in the preconditions for an eruption.

  17. Recent Two Distinct Eruptions at Sinabung and Kelud, Indonesia

    NASA Astrophysics Data System (ADS)

    Nakada, S.; Yoshimoto, M.; Maeno, F.; Iguchi, M.; Zaenudin, A.; Hendrasto, M.

    2014-12-01

    Two distinct eruptions occurred in 2014 at Sinabung and Kelud volcanoes in Indonesia. Lava dome-forming eruption started at Sinabung volcano, N Sumatra, in the end of 2013, which was preceded by the phreatic events since 2010 and shallow inflation with high seismicity since 3 months before eruption. The 2010 eruption was the first historic eruption, and the latest eruption geologically recorded occurred in the 9 to 10th Century. The eruption had continued in a nearly constant rate of magma effusion as of the summer of 2014. The lava complex extended on the SE slope (~2.5 km long from the source), frequently generating pyroclastic flows. The volume of erupted magma reached about 0.1 km3 in the 2014 summer. The lava is porphyritic andesite (SiO2 ~57%). The existence of mafic blobs in rocks and plagioclase microlites more calcic than the phenocryst rims, and the absence of breakdown rim on hornblende phenocrysts suggest magma mixing prior to eruption and relatively fast magma ascent. On the other hand, the Plinian eruption began at Kelud volcano, W Java on the evening of February 13, 2014, which had declined almost within about 6 hours. The eruption cloud rose to 18-25 km in altitude, and tephra deposited on extensive areas. The precursory seismic activity started two weeks before eruption and the intensity increased with time. This short but explosive eruption was one of recent large eruptions (VEI 4) at Kelud, which had repeated every ~20 years. A lava dome of 0.035 km3 was accidentally (?) formed within the crater in 2007-2008. The total volume of tephra of the 2014 eruption is 0.2-0.3 km3 in DRE. The magma is crystal-rich basaltic andesite (SiO2 ~56%; phenocryst proportion of ~60%). The petrological characteristics are close to the 2007-2008 dome lava except higher crystallinity in the latter. Mobilization of crystal-rich chamber magma probably was brought by intrusion of new magma. Thus, these recent examples in Indonesia are less-explosive and explosive

  18. Mass eruptions from the Sun

    NASA Astrophysics Data System (ADS)

    Green, Lucie

    2015-08-01

    This review talk will address the recent developments and current understanding of the physical mechanisms that underlie the ejection of matter and magnetic field from the atmosphere of the Sun, known as coronal mass ejections. These eruptions are intitiated within and between active regions throughout an active region's entire lifetime; from the emergence phase, when strong and concentrated magnetic fields are present, through the long decay phase during which time the active region magnetic field fragments and disperses over a larger and larger area, eventually fading into the background quiet sun magnetic field. All coronal mass ejection models invoke the presence of a twisted magnetic field configuration known as a magnetic flux rope either before or after eruption. The observational identification of these structures using remote sensing data of the lower solar atmosphere will be discussed. Do such magnetic field configurations exist in the solar atmosphere prior to the eruption? And if so what can they tell us about the physical mechanisms that trigger and drive coronal mass ejections and the timescales over which an eruptive magnetic field configuration forms? However, not all coronal mass ejections are easily identifiable at the Sun. For example, in situ observations of coronal mass ejections in interplanetary space reveal small magnetic flux rope coronal mass ejections which are not detected leaving the Sun using the remote sensing data. And so-called stealth coronal mass ejections which also have no lower atmosphere signatures. Are there different populations of flux ropes that have different origins? And what might this say about the physical mechanisms behind coronal mass ejections and the consequences for the Sun's evolving global magnetic field?

  19. Dynamics and pre-eruptive conditions of catastrophic, ignimbrite-producing eruptions from the Yenkahe Caldera, Vanuatu

    NASA Astrophysics Data System (ADS)

    Firth, Chris W.; Cronin, Shane J.; Turner, Simon P.; Handley, Heather K.; Gaildry, Clement; Smith, Ian

    2015-12-01

    A combined stratigraphic and geochemical examination of ~ 43 kyr of volcanic activity is presented for the Yenkahe Caldera, a mafic-intermediate volcanic system on the island of Tanna, in the Vanuatu Arc. Through this period two catastrophic ignimbrite-producing eruptions have occurred: the Siwi eruption and the older, Old Tanna Ignimbrite eruption. The latter was previously linked with a different edifice to the north-east, however re-examination has shown it was derived from the Yenkahe Caldera. Radiocarbon dating of this ignimbrite gives an age of ~ 43 kyr B.P. Both eruptions produced voluminous ignimbrite sheets, however differences in deposit sequences show that the eruptions followed distinct courses. Deposits from the more recent Siwi eruption display greater evidence for phreatomagmatic phases during eruption onset. Both ignimbrites are distributed asymmetrically about the caldera, indicating partial collapse in each case. The early stages of the Siwi eruption produced directed pyroclastic surges and spatter fountains. Between these two major eruptions, volcanic activity was maintained through the formation of small, discrete volcanic cones, such as Yasur, which is active today. Whole rock major and trace element data show that intra-caldera activity between cataclysmic eruptions produced magmas of uniform basaltic-trachy-andesitic composition (SiO2 ~ 56 wt.%). Minerals within these lavas appear to be in equilibrium with their host. The Siwi eruption produced the most evolved, trachy-andesitic magma (SiO2 > 58 wt.%), while the Old Tanna eruption is associated with less evolved, basaltic-andesite magma (SiO2 ~ 53 wt.%). Juvenile clasts from both ignimbrites display diverse mineral chemistry and mineral disequilibrium textures. From these variations in geochemistry and petrology we suggest that a crystal mush or resident magma remained following low-magnitude, intra-caldera activity. MELTS modelling suggest that this was stored at shallow depths, equivalent

  20. Eruption and degassing dynamics of the major August 2015 Piton de la Fournaise eruption

    NASA Astrophysics Data System (ADS)

    Di Muro, Andrea; Arellano, Santiago; Aiuppa, Alessandro; Bachelery, Patrick; Boudoire, Guillaume; Coppola, Diego; Ferrazzini, Valerie; Galle, Bo; Giudice, Gaetano; Gurioli, Lucia; Harris, Andy; Liuzzo, Marco; Metrich, Nicole; Moune, Severine; Peltier, Aline; Villeneuve, Nicolas; Vlastelic, Ivan

    2016-04-01

    Piton de la Fournaise (PdF) shield volcano is one of the most active basaltic volcanoes in the World with one eruption every nine months, on average. This frequent volcanic activity is broadly bimodal, with frequent small volume, short lived eruptions (< 30 Mm3, most being < 10 Mm3) and less frequent relatively large (50-210 Mm3) and long lasting (months) eruptions. After the major caldera forming event of 2007, the volcano produced several short lived small volume summit to proximal eruptions of relatively evolved cotectic magmas and relatively long repose periods (up to 3.5 years between 2010 and 2014). The August 2015 eruption was the first large (45±15 Mm3) and long lasting (2 months) eruption since 2007 and the only event to be fully monitored by the new gas geochemical network of Piton de la Fournaise volcanological observatory (DOAS, MultiGaS, diffuse CO2 soil emissions). Regular lava and tephra sampling was also performed for geochemical and petrological analysis. The eruption was preceded by a significant increase in CO2 soil emissions at distal soil stations (ca. 15 km from the summit), with CO2 enrichment also being recorded at summit low temperature fumaroles. Eruptive products were spectacularly zoned, with plagioclase and pyroxene being abundant in the early erupted products and olivine being the main phase in the late-erupted lavas. Total gas emissions at the eruptive vent underwent a decrease during the first half of the eruption and then an increase, mirroring the time evolution of magma discharge rate (from 5-10 m3/s in September to 15-30 m3/s in late-October) and the progressive change in magma composition. In spite of significant evolution in magma and gas output, CO2/SO2 ratios in high temperature gases remained quite low (< 0.3) and with little temporal change. Geochemical data indicated that this relatively long-lived eruption corresponded to the progressive drainage of most of the shallow part of PdF plumbing system, triggered by a new

  1. An Erupted Silent Tumour.

    PubMed

    Kudva, Adarsh; Chithra, A; Rao, Nirmala N; Cariappa, K M

    2016-07-01

    Odontomas are the most common odontogenic tumors of the oral cavity which are nonaggressive, hamartomatous in nature consisting of enamel, dentin and cementum. They are called as composite because they contain more than one type of tissue. They are generally asymptomatic, hence recognised on routine radiologic examination. The compound odontoma is composed of multiple small tooth like structures, whereas the complex odontoma consists of a conglomerate mass of enamel and dentine, which bears no anatomical similarity to the tooth. The eruption and infection of odontoma are uncommon, only few cases of erupted complex odontoma are reported in the literature. We report a case of silent erupting complex odontoma. PMID:27408461

  2. Depth of origin of magma in eruptions.

    PubMed

    Becerril, Laura; Galindo, Ines; Gudmundsson, Agust; Morales, Jose Maria

    2013-01-01

    Many volcanic hazard factors--such as the likelihood and duration of an eruption, the eruption style, and the probability of its triggering large landslides or caldera collapses--relate to the depth of the magma source. Yet, the magma source depths are commonly poorly known, even in frequently erupting volcanoes such as Hekla in Iceland and Etna in Italy. Here we show how the length-thickness ratios of feeder dykes can be used to estimate the depth to the source magma chamber. Using this method, accurately measured volcanic fissures/feeder-dykes in El Hierro (Canary Islands) indicate a source depth of 11-15 km, which coincides with the main cloud of earthquake foci surrounding the magma chamber associated with the 2011-2012 eruption of El Hierro. The method can be used on widely available GPS and InSAR data to calculate the depths to the source magma chambers of active volcanoes worldwide. PMID:24067336

  3. Depth of origin of magma in eruptions

    PubMed Central

    Becerril, Laura; Galindo, Ines; Gudmundsson, Agust; Morales, Jose Maria

    2013-01-01

    Many volcanic hazard factors - such as the likelihood and duration of an eruption, the eruption style, and the probability of its triggering large landslides or caldera collapses - relate to the depth of the magma source. Yet, the magma source depths are commonly poorly known, even in frequently erupting volcanoes such as Hekla in Iceland and Etna in Italy. Here we show how the length-thickness ratios of feeder dykes can be used to estimate the depth to the source magma chamber. Using this method, accurately measured volcanic fissures/feeder-dykes in El Hierro (Canary Islands) indicate a source depth of 11–15 km, which coincides with the main cloud of earthquake foci surrounding the magma chamber associated with the 2011–2012 eruption of El Hierro. The method can be used on widely available GPS and InSAR data to calculate the depths to the source magma chambers of active volcanoes worldwide. PMID:24067336

  4. Volcanic Eruptions in Kamchatka

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Sheveluch Stratovolcano Click on the image for full resolution TIFF Klyuchevskoy Stratovolcano Click on the image for full resolution TIFF

    One of the most volcanically active regions of the world is the Kamchatka Peninsula in eastern Siberia, Russia. It is not uncommon for several volcanoes to be erupting at the same time. On April 26, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radioneter (ASTER) on NASA's Terra spacecraft captured these images of the Klyuchevskoy and Sheveluch stratovolcanoes, erupting simultaneously, and 80 kilometers (50 miles) apart. Over Klyuchevskoy, the thermal infrared data (overlaid in red) indicates that two open-channel lava flows are descending the northwest flank of the volcano. Also visible is an ash-and-water plume extending to the east. Sheveluch volcano is partially cloud-covered. The hot flows highlighted in red come from a lava dome at the summit. They are avalanches of material from the dome, and pyroclastic flows.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra spacecraft. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining

  5. Geomorphic consequences of volcanic eruptions in Alaska: A review

    NASA Astrophysics Data System (ADS)

    Waythomas, Christopher F.

    2015-10-01

    Eruptions of Alaska volcanoes have significant and sometimes profound geomorphic consequences on surrounding landscapes and ecosystems. The effects of eruptions on the landscape can range from complete burial of surface vegetation and preexisting topography to subtle, short-term perturbations of geomorphic and ecological systems. In some cases, an eruption will allow for new landscapes to form in response to the accumulation and erosion of recently deposited volcaniclastic material. In other cases, the geomorphic response to a major eruptive event may set in motion a series of landscape changes that could take centuries to millennia to be realized. The effects of volcanic eruptions on the landscape and how these effects influence surface processes has not been a specific focus of most studies concerned with the physical volcanology of Alaska volcanoes. Thus, what is needed is a review of eruptive activity in Alaska in the context of how this activity influences the geomorphology of affected areas. To illustrate the relationship between geomorphology and volcanic activity in Alaska, several eruptions and their geomorphic impacts will be reviewed. These eruptions include the 1912 Novarupta-Katmai eruption, the 1989-1990 and 2009 eruptions of Redoubt volcano, the 2008 eruption of Kasatochi volcano, and the recent historical eruptions of Pavlof volcano. The geomorphic consequences of eruptive activity associated with these eruptions are described, and where possible, information about surface processes, rates of landscape change, and the temporal and spatial scale of impacts are discussed. A common feature of volcanoes in Alaska is their extensive cover of glacier ice, seasonal snow, or both. As a result, the generation of meltwater and a variety of sediment-water mass flows, including debris-flow lahars, hyperconcentrated-flow lahars, and sediment-laden water floods, are typical outcomes of most types of eruptive activity. Occasionally, such flows can be quite large

  6. Geomorphic Consequences of Volcanic Eruptions in Alaska: A Review

    USGS Publications Warehouse

    Waythomas, Christopher F.

    2015-01-01

    Eruptions of Alaska volcanoes have significant and sometimes profound geomorphic consequences on surrounding landscapes and ecosystems. The effects of eruptions on the landscape can range from complete burial of surface vegetation and preexisting topography to subtle, short-term perturbations of geomorphic and ecological systems. In some cases, an eruption will allow for new landscapes to form in response to the accumulation and erosion of recently deposited volcaniclastic material. In other cases, the geomorphic response to a major eruptive event may set in motion a series of landscape changes that could take centuries to millennia to be realized. The effects of volcanic eruptions on the landscape and how these effects influence surface processes has not been a specific focus of most studies concerned with the physical volcanology of Alaska volcanoes. Thus, what is needed is a review of eruptive activity in Alaska in the context of how this activity influences the geomorphology of affected areas. To illustrate the relationship between geomorphology and volcanic activity in Alaska, several eruptions and their geomorphic impacts will be reviewed. These eruptions include the 1912 Novarupta–Katmai eruption, the 1989–1990 and 2009 eruptions of Redoubt volcano, the 2008 eruption of Kasatochi volcano, and the recent historical eruptions of Pavlof volcano. The geomorphic consequences of eruptive activity associated with these eruptions are described, and where possible, information about surface processes, rates of landscape change, and the temporal and spatial scale of impacts are discussed.A common feature of volcanoes in Alaska is their extensive cover of glacier ice, seasonal snow, or both. As a result, the generation of meltwater and a variety of sediment–water mass flows, including debris-flow lahars, hyperconcentrated-flow lahars, and sediment-laden water floods, are typical outcomes of most types of eruptive activity. Occasionally, such flows can be quite

  7. A Nanolite Record of Eruption Style Transition

    NASA Astrophysics Data System (ADS)

    Mujin, M.; Nakamura, M.

    2014-12-01

    Microlites in pyroclasts have been intensively studied to understand magma ascent processes. However, microlites do not record the explosive-effusive transitions in sub-Plinian eruptions when such transitions are governed by the shallow level degassing rather than by the magma ascent rate. To overcome this limitation, we studied the "nanolites" in the quenched products of the 2011 Shinmoedake, Kirishima Volcanic Group, Kyusyu Japan1. Nanolites are the nanometer-scale components of the groundmass minerals and exhibit a steeper slope of crystal size distribution than that of the microlites2. In the 2011 Shinmoedake eruption, the style of activity had undergone transformations from sub-Plinian eruption to Vulcanian explosion and intermittent effusion of lava3. We found that, although the products formed by different eruptive activities have similar microlite characteristics, such products can be distinguished clearly by their mineral assemblage of nanolites. The samples of pumices of sub-Plinian eruptions and Vulcanian explosions and the dense juvenile fragments of lava (in descending order of explosivity) contained, respectively, nanolites of low-Ca pyroxene, low-Ca pyroxene + plagioclase, and low-Ca pyroxene + plagioclase + Fe-Ti oxides. Nanolites are assumed to crystallize when undercooling of the magma due primarily to dehydration increases rapidly near the surface. The water contents of the interstitial glass indicate that the quenched depths did not differ greatly between eruption styles. Hence, the different nanolite assemblages of each eruption style are assumed to have resulted from differences in magma residence time near the surface. Thus, we propose that nanolites in pyroclasts have the potential to indicate the physicochemical conditions of magma at the transition points of eruption styles. References 1) Mujin and Nakamura, 2014, Geology, v.42, p.611-614 2) Sharp et al., 1996, Bull. Volcanol, v.57, p.631-640 3) Miyabuchi et al, 2013, J. Volcanol

  8. Nyiragongo Volcano before the Eruption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nyiragongo is an active stratovolcano situated on the Eastern African Rift; it is part of Africa's Virunga Volcanic Chain. In a massive eruption that occurred on January 17, 2002, Nyiragongo sent a vast plume of smoke and ash skyward, and three swifly-moving rivers of lava streaming down its western and eastern flanks. Previous lava flows from Nyiragongo have been observed moving at speeds of up to 40 miles per hour (60 kph). The lava flows from the January 17 eruption destroyed more than 14 villages in the surrounding countryside, forcing tens of thousands to flee into the neighboring country of Rwanda. Within one day the lava ran to the city of Goma, situated on the northern shore of Lake Kivu about 12 miles (19 km) south of Nyiragongo. The lava cut a 200 foot (60 meter) wide swath right through Goma, setting off many fires, as it ran into Lake Kivu. Goma, the most heavily populated city in eastern Democratic Republic of Congo, is home to about 400,000 people. Most of these citizens were forced to flee, while many have begun to return to their homes only to find their homes destroyed. This true-color scene was captured by the Enhanced Thematic Mapper Plus (ETM+), flying aboard the Landsat 7 satellite, on December 11, 2001, just over a month before the most recent eruption. Nyiragongo's large crater is clearly visible in the image. As recently as June 1994, there was a large lava lake in the volcano's crater which had since solidified. The larger Nyamuragira Volcano is located roughly 13 miles (21 km) to the north of Nyiragongo. Nyamuragira last erupted in February and March 2001. That eruption was also marked by columns of erupted ash and long fluid lava flows, some of which are apparent in the image as dark greyish swaths radiating away from Nyamuragira. Both peaks are also notorious for releasing large amounts of sulfur dioxide, which presents another health hazard to people and animals living in close proximity. Image by Robert Simmon, based on data supplied

  9. Snake Filament Eruption

    NASA Video Gallery

    A very long solar filament that had been snaking around the Sun erupted on Dec. 6, 2010 with a flourish. NASA's Solar Dynamics Observatory (SDO) caught the action in dramatic detail in extreme ultr...

  10. Generalized eruptive syringomas.

    PubMed

    Jamalipour, Mahnaz; Heidarpour, Mitra; Rajabi, Parvin

    2009-01-01

    Generalized eruptive syringoma is a rare clinical presentation of a benign adnexal tumor that derives from the intraepidermal portion of the eccrine sweat ducts. It presents as successive crops of small flesh-colored papules on the anterior body surfaces. It generally occurs in the peripubertal period. Treatment of this benign condition is cosmetic only. A case of a 28-year-old female with an eight-year history of eruptive syringoma is presented. PMID:20049275

  11. Eruption Mechanism of the 10th Century Eruption in Baitoushan Volcano, China/North Korea

    NASA Astrophysics Data System (ADS)

    Shimano, T.; Miyamoto, T.; Nakagawa, M.; Ban, M.; Maeno, F.; Nishimoto, J.; Jien, X.; Taniguchi, H.

    2005-12-01

    Baitoushan volcano, China/North Korea, is one of the most active volcanoes in Northeastern Asia, and the 10th century eruption was the most voluminous eruption in the world in recent 2000 years. The sequence of the eruption reconstructed recently consists mainly of 6 units of deposits (Miyamoto et al., 2004); plinian airfall (unit B), large pyroclastic flow (unit C), plinian airfall with some intra- plinian pyroclastic flows (unit D), sub-plinian airfall (unit E), and large pyroclastic flow (unit F) with base surge (unit G) in ascending order. The magma erupted during steady eruption in earlier phase was comendite (unit B-C; Phase 1), whereas the magma during fluctuating eruptions in later phase is characterized by trachyte to trachyandesite with various amount of comendite (unit D-G; Phase 2). The wide variety in composition and occurrence of banded pumices strongly indicate mixing or mingling of the two magmas just prior to or during the eruption. The initial water contents had been determined for comendite by melt inclusion analyses (ca. 5.2 wt.%; Horn and Schmincke, 2000). Although the initial water content of the trachytic magma has not been correctly determined yet, the reported water contents of trachytic melt inclusions are lower (3-4 wt.%) than those of comenditic melt (Horn and Schmincke, 2000). We investigated juvenile materials of the eruption sequentially in terms of vesicularity, H2O content in matrix glass and textural characteristics. The vesicularity of pumices are generally high (>0.75) for all units. The residual water contents of the comenditic pumices during Phase 1 are relatively uniform (1.6 wt.%), whereas those of the trachytic scoria during Phase 2 and gray pumices during Phase 1 are low (ca. 0.7-1.3 wt.%). These facts may indicate that the difference in the initial water content, rather than the ascent mechanism of magma, controls the steadiness or fluctuation in eruption styles and the mass flux during the eruption.

  12. Influence of seismicity on the Lusi mud eruption

    NASA Astrophysics Data System (ADS)

    Rudolph, Maxwell L.; Manga, Michael; Tingay, Mark; Davies, Richard J.

    2015-09-01

    Earthquakes trigger the eruption of mud and magmatic volcanoes and influence ongoing eruptive activity. One mechanism that could trigger an eruption is clay liquefaction. Here we model the propagation of seismic waves beneath the Lusi mud eruption (East Java, Indonesia) using available seismic velocity and density models to assess the effect of subsurface structure on the amplification of incident seismic waves. We find that using an updated subsurface density and velocity structure, there is no significant amplification of incident seismic energy in the Upper Kalibeng Formation, the source of the erupting solids. Hence, the hypothesis that the Lusi eruption was triggered by clay liquefaction appears unlikely to be correct. Independent constraints from gas chemistry as well as analyses of drilling activities at the nearby Banjar-Panji 1 gas exploration well and an analysis of the effects of other earthquakes all favor a drilling trigger.

  13. Russian eruption warning systems for aviation

    USGS Publications Warehouse

    Neal, C.; Girina, O.; Senyukov, S.; Rybin, A.; Osiensky, J.; Izbekov, P.; Ferguson, G.

    2009-01-01

    More than 65 potentially active volcanoes on the Kamchatka Peninsula and the Kurile Islands pose a substantial threat to aircraft on the Northern Pacific (NOPAC), Russian Trans-East (RTE), and Pacific Organized Track System (PACOTS) air routes. The Kamchatka Volcanic Eruption Response Team (KVERT) monitors and reports on volcanic hazards to aviation for Kamchatka and the north Kuriles. KVERT scientists utilize real-time seismic data, daily satellite views of the region, real-time video, and pilot and field reports of activity to track and alert the aviation industry of hazardous activity. Most Kurile Island volcanoes are monitored by the Sakhalin Volcanic Eruption Response Team (SVERT) based in Yuzhno-Sakhalinsk. SVERT uses daily moderate resolution imaging spectroradiometer (MODIS) satellite images to look for volcanic activity along this 1,250-km chain of islands. Neither operation is staffed 24 h per day. In addition, the vast majority of Russian volcanoes are not monitored seismically in real-time. Other challenges include multiple time-zones and language differences that hamper communication among volcanologists and meteorologists in the US, Japan, and Russia who share the responsibility to issue official warnings. Rapid, consistent verification of explosive eruptions and determination of cloud heights remain significant technical challenges. Despite these difficulties, in more than a decade of frequent eruptive activity in Kamchatka and the northern Kuriles, no damaging encounters with volcanic ash from Russian eruptions have been recorded. ?? Springer Science+Business Media B.V. 2009.

  14. Magma degassing during eruption through water-saturated porous rocks

    NASA Astrophysics Data System (ADS)

    Melnik, O. E.; Afanasyev, A. A.; Zarin, G. A.

    2016-05-01

    In the case of extrusive eruption, we consider the problem on magma degassing which rises in a volcano conduit crossing porous water-saturated rocks. We show that the intensity of outflow of volcanic gases into the rocks is comparable to the intensity of their transport with the rising magma. The magma degassing in the rocks substantially affects the eruption dynamics, in particular, the duration of the periods of eruptive activity.

  15. Deformation associated with the 1997 eruption of Okmok volcano, Alaska

    USGS Publications Warehouse

    Mann, Dorte; Freymueller, Jeffrey T.; Lu, Zhiming

    2002-01-01

    Okmok volcano, located on Umnak Island in the Aleutian chain, Alaska, is the most eruptive caldera system in North America in historic time. Its most recent eruption occurred in 1997. Synthetic aperture radar interferometry shows deflation of the caldera center of up to 140 cm during this time, preceded and followed by inflation of smaller magnitude. The main part of the observed deformation can be modeled using a pressure point source model. The inferred source is located between 2.5 and 5.0 km beneath the approximate center of the caldera and ???5 km from the eruptive vent. We interpret it as a central magma reservoir. The preeruptive period features inflation accompanied by shallow localized subsidence between the caldera center and the vent. We hypothesize that this is caused by hydrothermal activity or that magma moved away from the central chamber and toward the later vent. Since all historic eruptions at Okmok have originated from the same cone, this feature may be a precursor that indicates an upcoming eruption. The erupted magma volume is ???9 times the volume that can be accounted for by the observed preeruptive inflation. This indicates a much longer inflation interval than we were able to observe. The observation that reinflation started shortly after the eruption suggests that inflation spans the whole time interval between eruptions. Extrapolation of the average subsurface volume change rate is in good agreement with the long-term eruption frequency and eruption volumes of Okmok.

  16. Conduit dynamics in transitional rhyolitic activity recorded by tuffisite vein textures from the 2008-2009 Chaitén eruption

    NASA Astrophysics Data System (ADS)

    Saubin, Elodie; Tuffen, Hugh; Gurioli, Lucia; Owen, Jacqueline; Castro, Jonathan; Berlo, Kim; McGowan, Ellen; Schipper, C. Ian; Wehbe, Katia

    2016-04-01

    Conduit processes govern the mechanisms of hazardous silicic eruptions, but our understanding of complex conduit behaviour is far from complete. Observations of recent Chilean rhyolite eruptions have revealed the importance of hybrid activity, involving simultaneous explosive and effusive emissions from a common vent[1]. Such behaviour hinges upon the ability of gas to decouple from magma in the shallow conduit. Tuffisite veins are increasingly suspected to be a key facilitator of outgassing, as they repeatedly provide a transient permeable escape route for volcanic gases. However, we have limited insights into the interactions between tuffisites and foams that appear critical to efficient outgassing[2], and into how heterogeneous conduit magma responds to pressure perturbations related to repeated disruption or slip of dense magma plugs. Here we provide a detailed characterization of an exceptionally large tuffisite vein within a rhyolitic obsidian bomb ejected during transitional explosive-effusive activity at volcán Chaitén, Chile in May 2008. Vein textures and chemistry provide a time-integrated record of the invasion of a dense upper conduit plug by deeper fragmented magma. Quantitative textural analysis reveals diverse vesiculation histories of varied juvenile clast types. Using vesicle size distributions, bubble number densities, zones of diffusive water depletion, and glass H2O concentrations, we propose a multi-step degassing/fragmentation history, spanning deep degassing to explosive bomb ejection. Rapid decompression events of ~3-4 MPa are associated with fragmentation of foam and dense magma at ~200-300 metres depth in the conduit, permitting vertical gas and pyroclast mobility over >100-200 metres. Permeable pathway occlusion in the dense conduit plug by pyroclast accumulation and sintering preceded ultimate bomb ejection, which triggered a final bubble nucleation event. Our results highlight how the vesiculation response of magma to decompression

  17. Conduit dynamics in transitional rhyolitic activity recorded by tuffisite vein textures from the 2008-2009 Chaitén eruption

    NASA Astrophysics Data System (ADS)

    Saubin, Elodie; Tuffen, Hugh; Gurioli, Lucia; Owen, Jacqueline; Castro, Jonathan; Berlo, Kim; McGowan, Ellen; Schipper, C.; Wehbe, Katia

    2016-05-01

    The mechanisms of hazardous silicic eruptions are controlled by complex, poorly-understood conduit processes. Observations of recent Chilean rhyolite eruptions have revealed the importance of hybrid activity, involving simultaneous explosive and effusive emissions from a common vent. Such behaviour hinges upon the ability of gas to decouple from magma in the shallow conduit. Tuffisite veins are increasingly suspected to be a key facilitator of outgassing, as they repeatedly provide a transient permeable escape route for volcanic gases. Intersection of foam domains by tuffisite veins appears critical to efficient outgassing. However, knowledge is currently lacking into textural heterogeneities within shallow conduits, their relationship with tuffisite vein propagation, and the implications for fragmentation and degassing processes. Similarly, the magmatic vesiculation response to upper conduit pressure perturbations, such as those related to the slip of dense magma plugs, remains largely undefined. Here we provide a detailed characterization of an exceptionally large tuffisite vein within a rhyolitic obsidian bomb ejected during transitional explosive-effusive activity at Chaitén, Chile in May 2008. Vein textures and chemistry provide a time-integrated record of the invasion of a dense upper conduit plug by deeper fragmented magma. Quantitative textural analysis reveals diverse vesiculation histories of various juvenile clast types. Using vesicle size distributions, bubble number densities, zones of diffusive water depletion, and glass H2O concentrations, we propose a multi-step degassing/fragmentation history, spanning deep degassing to explosive bomb ejection. Rapid decompression events of ~3-4 MPa are associated with fragmentation of foam and dense magma at ~200-350 metres depth in the conduit, permitting vertical gas and pyroclast mobility over hundreds of metres. Permeable pathway occlusion in the dense conduit plug by pyroclast accumulation and sintering

  18. Setting of the Father's Day Eruption at Kilauea

    NASA Astrophysics Data System (ADS)

    Swanson, D. A.

    2007-12-01

    The Father's Day eruption and associated intrusion took place within a 10-km segment of Kilauea's east rift zone between Hi`iaka and Napau Craters--a segment that has had more numerous eruptions and intrusions than any other of comparable length during the past 200, probably the past 1000, years. Fifteen known eruptions started in this area in the past 200 years: 1840, 1922, 1923, 1962, August and October 1963, March and December 1965, August and October 1968, February and May 1969, May and November 1973, and March 1980 (only 3 cubic meters!). Three others, not previously designated as distinct eruptions despite having all the appropriate characteristics, took place during on-going eruptions: two in `Alo`i Crater in 1970 and 1972, and one in Napau Crater in 1997. Two of the largest shields on the east rift zone formed during long-lasting eruptions within this area--Kane Nui o Hamo at an unknown date, perhaps the 11-12th century, and Mauna Ulu (1969-1974). In addition, many small intrusions without eruptions are known. Seven short eruptions punctuated a prolonged eruption: four within the segment during the Mauna Ulu eruption, two at the summit and southwest rift zone during that same eruption, and one in Napau Crater in 1997 during the Pu`u `O`o eruption. Thus the Father's Day eruption is not unique by virtue of taking place during an ongoing eruption elsewhere along the rift zone. The increased frequency of activity in the segment during the 20th century is obvious, particularly after 1962. For most of the past 1,000 years, eruptions were centered at Kilauea's summit, with significant but lesser activity along the rift zones. A large summit deflation in 1924 ended the nearly continuous lava lake in Halemaumau, eventually leading to the past 5 decades of dominantly east rift zone activity. This segment of the rift zone contains most of the pit craters on Kilauea and gradually changes from a SE trend near the caldera to an ENE trend that characterizes the rest of

  19. Eruption column physics

    SciTech Connect

    Valentine, G.A.

    1997-03-01

    In this paper the author focuses on the fluid dynamics of large-scale eruption columns. The dynamics of these columns are rooted in multiphase flow phenomena, so a major part of the paper sets up a foundation on that topic that allows one to quickly assess the inherent assumptions made in various theoretical and experimental approaches. The first part is centered on a set of complex differential equations that describe eruption columns, but the focus is on a general understanding of important physical processes rather than on the mathematics. The author discusses briefly the relative merits and weaknesses of different approaches, emphasizing that the largest advances in understanding are made by combining them. He then focuses on dynamics of steady eruption columns and then on transient phenomena. Finally he briefly reviews the effects of varying behavior of the ambient medium through which an eruption column moves. These final sections will emphasize concepts and a qualitative understanding of eruption dynamics. This paper relies on principles of continuum mechanics and transport processes but does not go into detail on the development of those principles. 36 refs., 36 figs., 3 tabs.

  20. MASS COMPOSITION IN PRE-ERUPTION QUIET SUN FILAMENTS

    SciTech Connect

    Kilper, Gary; Gilbert, Holly; Alexander, David

    2009-10-10

    Filament eruptions are extremely important phenomena due to their association with coronal mass ejections and their effects on space weather. Little is known about the filament mass and composition in the eruption process, since most of the related research has concentrated on the evolution and disruption of the magnetic field. Following up on our previous work, we present here an analysis of nineteen quiet Sun filament eruptions observed by Mauna Loa Solar Observatory in Halpha and He I 10830 A that has identified a compositional precursor common to all of these eruptions. There is a combined trend of an apparent increase in the homogenization of the filament mass composition, with concurrent increases in absorption in Halpha and He I and in the level of activity, all starting at least one day prior to eruption. This finding suggests that a prolonged period of mass motions, compositional mixing, and possibly even extensive mass loading is occurring during the build up of these eruptions.

  1. Potential hazards from future volcanic eruptions in California

    SciTech Connect

    Miller, C.D.

    1989-01-01

    More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the last 10,000 yr. Past volcanic activity has ranged in scale and type from small rhyolitic and basaltic eruptions through large catastrophic rhyolitic eruptions. Volcanoes in California will erupt again, and they could have serious impacts on the health, safety, and economy of the State's citizens as well as that of neighboring states. The nature and probable distribution of potentially hazardous volcanic phenomena and their threat to people and property is described in this bulletin.

  2. Intrusion Triggering of Explosive Eruptions: Lessons Learned from EYJAFJALLAJÖKULL 2010 Eruptions and Crustal Deformation Studies

    NASA Astrophysics Data System (ADS)

    Sigmundsson, F.; Hreinsdottir, S.; Hooper, A. J.; Arnadottir, T.; Pedersen, R.; Roberts, M. J.; Oskarsson, N.; Auriac, A.; Decriem, J.; Einarsson, P.; Geirsson, H.; Hensch, M.; Ofeigsson, B. G.; Sturkell, E. C.; Sveinbjornsson, H.; Feigl, K.

    2010-12-01

    Gradual inflation of magma chambers often precedes eruptions at highly active volcanoes. During eruptions, rapid deflation occurs as magma flows out and pressure is reduced. Less is known about the deformation style at moderately active volcanoes, such as Eyjafjallajökull, Iceland, where an explosive summit eruption of trachyandesite beginning on 14 April 2010 caused exceptional disruption to air traffic. This eruption was preceded by an effusive flank eruption of olivine basalt from 20 March - 12 April 2010. Geodetic and seismic observations revealed the growth of an intrusive complex in the roots of the volcano during three months prior to eruptions. After initial horizontal growth, modelling indicates both horizontal and sub-vertical growth in three weeks prior the first eruption. The behaviour is attributed to subsurface variations in crustal stress and strength originating from complicated volcano foundations. A low-density layer may capture magma allowing pressure to build before an intrusion can ascend towards higher levels. The intrusive complex was formed by olivine basalt as erupted on the volcano flank 20 March - 12 April; the intrusive growth halted at the onset of this eruption. Deformation associated with the eruption onset was minor as the dike had reached close to the surface in the days before. Isolated eruptive vents opening on long-dormant volcanoes may represent magma leaking upwards from extensive pre-eruptive intrusions formed at depth. A deflation source activated during the summit eruption of trachyandesite is distinct from, and adjacent to, all documented sources of inflation in the volcano roots. Olivine basalt magma which recharged the volcano appears to have triggered the summit eruption, although the exact mode of triggering is uncertain. Scenarios include stress triggering or propagation of olivine basalt into more evolved magma. The trachyandesite includes crystals that can be remnants of minor recent intrusion of olivine basalt

  3. Jet noise recorded during discrete explosive eruptions

    NASA Astrophysics Data System (ADS)

    Scarlato, P.; Sesterhenn, J.; Taddeucci, J.

    2013-12-01

    Most commonly, acoustic studies of explosive volcanic activity focus on the infrasonic range, as related to large volumetric changes mostly associated with the liberation of pressurized gas. However, there are multiple potential sources of sound that accompany explosive activity, expected to cover a broad range of frequencies. Among the audible range are several mechanisms, generating sound in high-velocity jets of gas or gas-particle mixture entering the atmosphere. This types of sound, well-documented and investigated in physics and engineering literature, has been so far mostly neglected in the study of explosive eruptions, due to the high energy content of the jet noise in the infrasonic regime, despite the potential it holds for parameterizing and understanding eruption processes. High-speed imaging of Strombolian and Vulcanian explosive eruptions at several volcanoes allowed the visualization of acoustic waves generated during the emission of the eruptive gas-pyroclast mixture. The waves, visible only when travelling within dilute gas/aerosol plumes, are thought to cause a temporary phase change in the travel medium. Image analysis allows direct measurement of the apparent (projected) trajectory, wavelength and travel velocity of the waves. Synchronized audio recording from the same eruptions include frequency contents in agreement with the observed waves. The general features of the observed waves are compatible with jet noise originated by the gas-pyroclast mixture entering the atmosphere, opening the way for future comparison with the results of numerical simulations of explosive eruptions, and possibly setting the basis for new acoustic monitoring tools for explosive eruptions.

  4. A FLUX ROPE ERUPTION TRIGGERED BY JETS

    SciTech Connect

    Guo Juan; Zhang Hongqi; Deng Yuanyong; Lin Jiaben; Su Jiangtao; Liu Yu

    2010-03-10

    We present an observation of a filament eruption caused by recurrent chromospheric plasma injections (surges/jets) on 2006 July 6. The filament eruption was associated with an M2.5 two-ribbon flare and a coronal mass ejection (CME). There was a light bridge in the umbra of the main sunspot of NOAA 10898; one end of the filament was terminated at the region close to the light bridge, and recurrent surges were observed to be ejected from the light bridge. The surges occurred intermittently for about 8 hr before the filament eruption, and finally a clear jet was found at the light bridge to trigger the filament eruption. We analyzed the evolutions of the relative darkness of the filament and the loaded mass by the continuous surges quantitatively. It was found that as the occurrence of the surges, the relative darkness of the filament body continued growing for about 3-4 hr, reached its maximum, and kept stable for more than 2 hr until it erupted. If suppose 50% of the ejected mass by the surges could be trapped by the filament channel, then the total loaded mass into the filament channelwill be about 0.57x10{sup 16} g with a momentum of 0.57x10{sup 22} g cm s{sup -1} by 08:08 UT, which is a non-negligible effect on the stability of the filament. Based on the observations, we present a model showing the important role that recurrent chromospheric mass injection play in the evolution and eruption of a flux rope. Our study confirms that the surge activities can efficiently supply the necessary material for some filament formation. Furthermore, our study indicates that the continuous mass with momentum loaded by the surge activities to the filament channel could make the filament unstable and cause it to erupt.

  5. Characterize Eruptive Processes at Yucca Mountain, Nevada

    SciTech Connect

    G. Valentine

    2001-12-20

    This Analysis/Model Report (AMR), ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', presents information about natural volcanic systems and the parameters that can be used to model their behavior. This information is used to develop parameter-value distributions appropriate for analysis of the consequences of volcanic eruptions through a potential repository at Yucca Mountain. Many aspects of this work are aimed at resolution of the Igneous Activity Key Technical Issue (KTI) as identified by the Nuclear Regulatory Commission (NRC 1998, p. 3), Subissues 1 and 2, which address the probability and consequence of igneous activity at the proposed repository site, respectively. Within the framework of the Disruptive Events Process Model Report (PMR), this AMR provides information for the calculations in two other AMRs ; parameters described herein are directly used in calculations in these reports and will be used in Total System Performance Assessment (TSPA). Compilation of this AMR was conducted as defined in the Development Plan, except as noted. The report begins with considerations of the geometry of volcanic feeder systems, which are of primary importance in predicting how much of a potential repository would be affected by an eruption. This discussion is followed by one of the physical and chemical properties of the magmas, which influences both eruptive styles and mechanisms for interaction with radioactive waste packages. Eruptive processes including the ascent velocity of magma at depth, the onset of bubble nucleation and growth in the rising magmas, magma fragmentation, and velocity of the resulting gas-particle mixture are then discussed. The duration of eruptions, their power output, and mass discharge rates are also described. The next section summarizes geologic constraints regarding the interaction between magma and waste packages. Finally, they discuss bulk grain size produced by relevant explosive eruptions and grain shapes.

  6. Long-term evolution of erupted magma chemistry

    NASA Astrophysics Data System (ADS)

    Caricchi, L.; Simpson, G.

    2014-12-01

    Magmatic reservoirs that feed explosive volcanic activity at the surface are constructed by the periodic injection of magma into the upper crust. The long-term magma flux controls the thermal evolution of these magmatic reservoirs and therefore the possibility of accumulating eruptible magma in the plumbing system of volcanoes. Magma flux, in combination with the periodicity of magma injection, regulates the frequency and magnitude of volcanic eruptions. We combined thermal and mechanical modelling with Monte Carlo simulations to compute the temporal evolution of the chemistry of eruptible magma (<50 vol. % crystals) in systems growing at different characteristic magma fluxes. We simulated the periodic injection of andesitic magma in the upper crust and trace the volume and chemistry of the eruptible magma together with the evolution of the overpressure within the reservoir. Eruptions are prescribed to occur once overpressure reached critical values (1-40 MPa). The calculations show that eruptions of rhyolitic compositions are rare and can only occur after a stage of prolonged thermal maturation of a magmatic reservoir (lasting a few hundredths of thousands of years). Additionally, eruptions of chemically evolved rocks are restricted to a specific range of physical conditions. Interestingly, the probability of eruptions of rhyolitic compositions increases substantially once the injection of magma into the magmatic reservoir ceases, which would imply that rhyolitic eruptions (not produced by partial melting of continental crust) are most likely to occur during the waning (not waxing) stages of magmatic activity.

  7. Acneiform facial eruptions

    PubMed Central

    Cheung, Melody J.; Taher, Muba; Lauzon, Gilles J.

    2005-01-01

    OBJECTIVE To summarize clinical recognition and current management strategies for four types of acneiform facial eruptions common in young women: acne vulgaris, rosacea, folliculitis, and perioral dermatitis. QUALITY OF EVIDENCE Many randomized controlled trials (level I evidence) have studied treatments for acne vulgaris over the years. Treatment recommendations for rosacea, folliculitis, and perioral dermatitis are based predominantly on comparison and open-label studies (level II evidence) as well as expert opinion and consensus statements (level III evidence). MAIN MESSAGE Young women with acneiform facial eruptions often present in primary care. Differentiating between morphologically similar conditions is often difficult. Accurate diagnosis is important because treatment approaches are different for each disease. CONCLUSION Careful visual assessment with an appreciation for subtle morphologic differences and associated clinical factors will help with diagnosis of these common acneiform facial eruptions and lead to appropriate management. PMID:15856972

  8. The 1977 eruption of Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Moore, R.B.; Helz, R.T.; Dzurisin, D.; Eaton, G.P.; Koyanagi, R.Y.; Lipman, P.W.; Lockwood, J.P.; Puniwai, G.S.

    1980-01-01

    Kilauea volcano began to erupt on September 13, 1977, after a 21.5-month period of quiescence. Harmonic tremor in the upper and central east rift zone and rapid deflation of the summit area occurred for 22 hours before the outbreak of surface activity. On the first night, spatter ramparts formed along a discontinuous, en-echelon, 5.5-km-long fissure system that trends N70??E between two prehistoric cones, Kalalua and Puu Kauka. Activity soon became concentrated at a central vent that erupted sporadically until September 23 and extruded flows that moved a maximum distance of 2.5 km to the east. On September 18, new spatter ramparts began forming west of Kalalua, extending to 7 km the length of the new vent system. A vent near the center of this latest fissure became the locus of sustained fountaining and continued to extrude spatter and short flows intermittently until September 20. The most voluminous phase of the eruption began late on September 25. A discontinuous spatter rampart formed along a 700-m segment near the center of the new, 7-km-long fissure system; within 24 hours activity became concentrated at the east end of this segment. One flow from the 35-m-high cone that formed at this site moved rapidly southeast and eventually reached an area 10 km from the vent and 700 m from the nearest house in the evacuated village of Kalapana. We estimate the total volume of material produced during this 18-day eruption to be 35 ?? 106 m3. Samples from active vents and flows are differentiated quartz-normative tholeiitic basalt, similar in composition to lavas erupted from Kilauea in 1955 and 1962. Plagioclase is the only significant phenocryst; augite, minor olivine, and rare orthopyroxene and opaque oxides accompany it as microphenocrysts. Sulfide globules occur in fresh glass and as inclusions in phenocrysts in early 1977 lavas; their absence in chemically-similar basalt from the later phases of the eruption suggests that more extensive intratelluric degassing

  9. Preliminary results from Submarine Ring of Fire 2012 - NE Lau: First explorations of hydrothermally active volcanoes across the supra-subduction zone and a return to the West Mata eruption site

    NASA Astrophysics Data System (ADS)

    Resing, J.; Embley, R. W.

    2012-12-01

    Several expeditions in the past few years have shown that the NE Lau basin has one of the densest concentrations of volcanically and hydrothermally active volcanoes on the planet. In 2008 two active submarine volcanic eruptions were discovered during a one week period and subsequent dives with the Jason remotely operated vehicle at one of the sites (West Mata) revealed an active boninite eruption taking place at 1200 m depth. Two dives at the other revealed evidence for recent eruption along the NE Lau Spreading Center. Several more expeditions in 2010-11 discovered additional evidence about the extent and types of hydrothermal activity in this area. Data from CTDO (conductivity, temperature, depth, optical) vertical casts, tow-yos, and towed camera deployments revealed more than 15 hydrothermal sites at water depths from ~800 to 2700 m that include sites from the magmatic arc, the "rear arc," and the back arc spreading centers. These sites range from high temperature black smoker sulfide-producing systems to those dominated by magmatic degassing. Dives by remotely operated vehicle (Quest 4000) in September 2012 will explore these sites and return samples for chemical, biological and geologic studies. One of the dives will be a return visit to West Mata volcano, the site of the deepest submarine eruption yet observed (in 2009). Recent multibeam data reveal large changes in West Mata's summit, suggesting that the nature of the eruption and the location of the erupting vents may have changed. In addition to the preliminary results from the science team, we will also discuss our use and experience with continuous live video transmission (through the High Definition video camera on the Quest 4000) back to shore via satellite and through the internet. Submarine Ring of Fire 2012 Science Team: Bradley Tebo, Bill Chadwick, Ed Baker, Ken Rubin, Susan Merle, Timothy Shank, Sharon Walker, Andra Bobbitt, Nathan Buck, David Butterfield, Eric Olson, John Lupton, Richard Arculus

  10. Assessing the volcanic hazard for Rome: 40Ar/39Ar and In-SAR constraints on the most recent eruptive activity and present-day uplift at Colli Albani Volcanic District

    NASA Astrophysics Data System (ADS)

    Marra, F.; Gaeta, M.; Giaccio, B.; Jicha, B. R.; Palladino, D. M.; Polcari, M.; Sottili, G.; Taddeucci, J.; Florindo, F.; Stramondo, S.

    2016-07-01

    We present new 40Ar/39Ar data which allow us to refine the recurrence time for the most recent eruptive activity occurred at Colli Albani Volcanic District (CAVD) and constrain its geographic area. Time elapsed since the last eruption (36 kyr) overruns the recurrence time (31 kyr) in the last 100 kyr. New interferometric synthetic aperture radar data, covering the years 1993-2010, reveal ongoing inflation with maximum uplift rates (>2 mm/yr) in the area hosting the most recent (<200 ka) vents, suggesting that the observed uplift might be caused by magma injection within the youngest plumbing system. Finally, we frame the present deformation within the structural pattern of the area of Rome, characterized by 50 m of regional uplift since 200 ka and by geologic evidence for a recent (<2000 years) switch of the local stress-field, highlighting that the precursors of a new phase of volcanic activity are likely occurring at the CAVD.

  11. Eruptions from the Sun

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-11-01

    The Sun often exhibits outbursts, launching material from its surface in powerful releases of energy. Recent analysis of such an outburst captured on video by several Sun-monitoring spacecraft may help us understand the mechanisms that launch these eruptions.Many OutburstsSolar jets are elongated, transient structures that are thought to regularly release magnetic energy from the Sun, contributing to coronal heating and solar wind acceleration. Coronal mass ejections (CMEs), on the other hand, are enormous blob-like explosions, violently ejecting energy and mass from the Sun at incredible speeds.But could these two types of events actually be related? According to a team of scientists at the University of Science and Technology of China, they may well be. The team, led by Jiajia Liu, has analyzed observations of a coronal jet that they believe prompted the launch of a powerful CME.Observing an ExplosionGif of a movie of the CME, taken by the Solar Dynamics Observatorys Atmospheric Imaging Assembly at a wavelength of 304. The original movie can be found in the article. [Liu et al.]An army of spacecraft was on hand to witness the event on 15 Jan 2013 including the Solar Dynamics Observatory (SDO), the Solar and Heliospheric Observatory (SOHO), and the Solar Terrestrial Relations Observatory (STEREO). The instruments on board these observatories captured the drama on the northern limb of the Sun as, at 19:32 UT, a coronal jet formed. Just eight minutes later, a powerful CME was released from the same active region.The fact that the jet and CME occurred in the same place at roughly the same time suggests theyre related. But did the initial motions of the CME blob trigger the jet? Or did the jet trigger the CME?Tying It All TogetherIn a recently published study, Liu and collaborators analyzed the multi-wavelength observations of this event to find the heights and positions of the jet and CME. From this analysis, they determined that the coronal jet triggered the release

  12. Drawing the Curtain on Enceladus' South-Polar Eruptions

    NASA Astrophysics Data System (ADS)

    Spitale, Joseph N.; Hurford, Terry A.; Rhoden, Alyssa R.; Berkson, Emily E.; Platts, Symeon S.

    2015-11-01

    For a comprehensive description of Enceladus' south-polar eruptions observed at high resolution, they must be represented as broad curtains rather than discrete jets. Meanders in the fractures from which the curtains of material erupt give rise to optical illusions that look like discrete jets, even along fractures with no local variations in eruptive activity, implying that many features previously identified as "jets" are in fact phantoms. By comparing Cassini images with model curtain eruptions, we are able to obtain maps of eruptive activity that are not biased by the presence of those phantom jets. The average of our activity maps over all times agrees well with thermal maps produced by Cassini CIRS. We can best explain the observed curtains by assuming spreading angles with altitude of up to 14° and zenith angles of up to 8°, for curtains observed in geometries that are sensitive to those quantities.

  13. Cause and risk of catastrophic eruptions in the Japanese Archipelago.

    PubMed

    Tatsumi, Yoshiyuki; Suzuki-Kamata, Keiko

    2014-01-01

    The Japanese Archipelago is characterized by active volcanism with variable eruption styles. The magnitude (M)-frequency relationships of catastrophic caldera-forming eruptions (M ≥ 7) are statistically different from those of smaller eruptions (M ≤ 5.7), suggesting that different mechanisms control these eruptions. We also find that volcanoes prone to catastrophic eruptions are located in regions of low crustal strain rate (<0.5 × 10(8)/y) and propose, as one possible mechanism, that the viscous silicic melts that cause such eruptions can be readily segregated from the partially molten lower crust and form a large magma reservoir in such a tectonic regime. Finally we show that there is a ∼1% probability of a catastrophic eruption in the next 100 years based on the eruption records for the last 120 ky. More than 110 million people live in an area at risk of being covered by tephra >20 cm thick, which would severely disrupt every day life, from such an eruption on Kyushu Island, SW Japan. PMID:25391319

  14. Cause and risk of catastrophic eruptions in the Japanese Archipelago

    PubMed Central

    TATSUMI, Yoshiyuki; SUZUKI-KAMATA, Keiko

    2014-01-01

    The Japanese Archipelago is characterized by active volcanism with variable eruption styles. The magnitude (M)-frequency relationships of catastrophic caldera-forming eruptions (M ≥ 7) are statistically different from those of smaller eruptions (M ≤ 5.7), suggesting that different mechanisms control these eruptions. We also find that volcanoes prone to catastrophic eruptions are located in regions of low crustal strain rate (<0.5 × 108/y) and propose, as one possible mechanism, that the viscous silicic melts that cause such eruptions can be readily segregated from the partially molten lower crust and form a large magma reservoir in such a tectonic regime. Finally we show that there is a ∼1% probability of a catastrophic eruption in the next 100 years based on the eruption records for the last 120 ky. More than 110 million people live in an area at risk of being covered by tephra >20 cm thick, which would severely disrupt every day life, from such an eruption on Kyushu Island, SW Japan. PMID:25391319

  15. Ash erupted during normal activity at Stromboli (Aeolian Islands, Italy) raises questions on how the feeding system works

    NASA Astrophysics Data System (ADS)

    D'Oriano, Claudia; Bertagnini, Antonella; Pompilio, Massimo

    2010-05-01

    Normal activity at Stromboli consists of continuous, non-explosive degassing, punctuated by mild explosions at a frequency of about 13 events/h. Each burst, lasting for a few seconds, throws to heights of 100-300 m incandescent scoriae, ash and blocks made of high-porphyritic (HP) degassed magma. During a multidisciplinary experiments on September 2008, ash samples emitted from 18 distinct explosions were collected with the aim of investigating magmatic and volcanic processes occurring in the conduits during the normal Strombolian activity on the basis of ash characterization. The selected samples are representative of the activity of two different craters (SW and NE) during three distinct days. After sieving, about 30 juvenile fragments (from the 0.5-1 mm size interval) were randomly hand-picked from each sample, and then mounted on double-adhesive tape on a glass slide. Single clasts were examined and photographed at the Scanning Electron Microscope (SEM) for identification of clast types, external morphology description and identification of secondary minerals. The same clasts were embedded in epoxy, sectioned and polished for textural and compositional analysis of the groundmass. Preliminary results indicate that Pele's hairs and fluidal, glassy fragments represent the majority (>50 vol%) of the juvenile material together with dense clasts (<30 vol%) in all the analysed samples, while crystals and lithic clasts are less than 20 vol%. Within the juvenile fraction a minor but significant amount of highly vesicular fragments (< 3 vol%) shows glass composition typical of deep-seated, volatile-rich, low-porphyritic (LP) magma. Until now the emission of the LP magma, as highly vesicular pumice, was associated exclusively with high energy explosions (paroxysms) (Bertagnini et al. 1999, Schiavi et al. 2009). The comparison of the morphological and textural features of these LP ash fragments let exclude that they are clasts recycled after the last paroxysm (15 March

  16. The influence of magma supply rate on eruption style and textures of erupted ash particles

    NASA Astrophysics Data System (ADS)

    Wright, H. M.; Cashman, K. V.

    2011-12-01

    Persistent low- to moderate-level eruptive activity of basaltic to andesitic volcanoes is difficult to monitor because small changes in magma supply rates can cause abrupt transitions in eruption style. Direct measurement of magma ascent rate is not possible; therefore, we must develop indirect measures of ascent rate. Here, we use a petrologic approach to this problem. We quantify textural variations in Vulcanian and Strombolian eruptive products (erupted between 1999-2006) from Tungurahua volcano, Ecuador. We compare average crystallinities of pyroclasts from a succession of ash eruptions with magma supply rates determined using satellite observations of plume heights and seismic recordings of explosion frequency. We show that tephra crystallinity correlates inversely with magma supply rate, similar to correlations described from decompression experiments of intermediate composition magma. We further suggest that the range of textures present in any individual sample indicates recycling from one eruption to the next and/or simultaneous eruption of particles with different crystallization histories. The correlation between crystallinity and magma supply rate is most easily explained by efficient degassing at very low pressures and degassing-driven crystallization between eruptions. A similar correlation has been shown at Crater Peak, USA (Gardner et al. 1998); Merapi, Indonesia (Hammer et al. 2000); Unzen, Japan (Nakada and Motomura, 1999); and Sakurajima, Japan (Miwa et al., 2009). Futhermore, systematic changes in crystallinity have been shown to extend across a range of eruption styles (including Vulcanian and Strombolian), as at Etna, Italy (Taddeucci et al. 2002) and Croscat, Spain (Cimarelli et al., 2010). This variation with eruption style suggests that the observed transition from intermittent Vulcanian explosions to more continuous periods of Strombolian eruptions and lava fountains can be explained simply by changes in the average crystal content of the

  17. Kimberlite ascent and eruption.

    PubMed

    Sparks, R S J; Brown, R J; Field, M; Gilbertson, M

    2007-12-13

    Wilson and Head model kimberlite ascent and eruption by considering the propagation of a volatile-rich dyke. Wilson and Head's model has features in common with Sparks et al., but it is inconsistent with geological observations and constraints on volatile solubility. Here we show that this may be due to erroneous physical assumptions. PMID:18075522

  18. The Eruptive Behavior of Klyuchevskoy Volcano, Kamchatka

    NASA Astrophysics Data System (ADS)

    Rose, S.; Ramsey, M.

    2008-12-01

    Klyuchevskoy volcano, one of the most active volcanoes in the northern Pacific, is located on the Kamchatka Peninsula in eastern Russia at the junction between the Kurile-Kamchatka and Aleutian Island Arcs. Its remote location and diversity of eruption styles make satellite-based monitoring and characterization of its eruptive activity essential. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor was launched in December 1999 on the NASA Terra satellite and has proven effective for the detection and monitoring of volcanic eruptions and their associated products. The goal of this investigation is to determine how well data from a broad spectral range at spatial resolutions under 100m/pixel can be used to characterize the 2005 and 2007 eruptions of a remote volcano during the harsh northern Pacific winter. The ASTER data presented here are supplemented by hand samples collected from the 2005 basaltic lava flows as well as high-spatial resolution thermal infrared data collected by a Forward Looking Infrared (FLIR) camera during field campaigns in August 2005 and 2007. Collectively, these data provide details regarding the composition, eruption rate, and eruptive mechanisms. Analysis of the data from all three ASTER subsystems reveals four main eruptive phases: a precursory, explosive, explosive-effusive, and cooling phase. These phases correlate to a gradual increase in maximum brightness temperatures followed by a rapid decrease. Close examination of FLIR data and digital photographs reveal the presence of a breakout point approximately 90 m below the rim of the nested summit crater, indicating a flow had breached the nested crater and traveled down the Krestovsky channel during both eruptions. Laboratory- derived TIR spectral data of the 2005 hand samples indicate good agreement with those obtained by ASTER after being reduced to the same spectral resolution. However, inherent errors of the spectra at longer wavelength indicate the

  19. Eruption Source Parameters for forecasting ash dispersion and deposition from vulcanian eruptions at Tungurahua volcano: Insights from field data from the July 2013 eruption

    NASA Astrophysics Data System (ADS)

    Parra, René; Bernard, Benjamin; Narváez, Diego; Le Pennec, Jean-Luc; Hasselle, Nathalie; Folch, Arnau

    2016-01-01

    Tungurahua volcano, located in the central area of the Ecuadorian Sierra, is erupting intermittently since 1999 alternating between periods of quiescence and explosive activity. Volcanic ash has been the most frequent and widespread hazard provoking air contamination episodes and impacts on human health, animals and crops in the surrounding area. After two months of quiescence, Tungurahua erupted violently on 14th July 2013 generating short-lived eruptive columns rising up to 9 km above the vent characterized as a vulcanian eruption. The resulting fallout deposits were sampled daily during and after the eruptions to determine grain size distributions and perform morphological and componentry analyses. Dispersion and sedimentation of ash were simulated numerically coupling the meteorological Weather Research Forecasting (WRF) with the volcanic ash dispersion FALL3D models. The combination of field and numerical studies allowed constraining the Eruption Source Parameters (ESP) for this event, which could be used to forecast ash dispersion and deposition from future vulcanian eruptions at Tungurahua. This set of pre-defined ESP was further validated using two different eruptions, as blind test, occurring on 16th December 2012 and 1st February 2014.

  20. An arcade-like eruptive prominence

    NASA Astrophysics Data System (ADS)

    Zhong, Shu-Hua; Zhan, La-Sheng

    2004-12-01

    An eruptive prominence happened on the east-northern limb of the Sun on March 7, 1991. It appeared in a relatively quiet region where any activity phenomena such as flare, filament and sunspot etc. was not found. The maximum height reachable of the prominence was 6.97×104km and its maximum length reached as 11.6×104km. The eruptive prominence might belong to the one of the middle-smaller scale according to its size in morphology. The course of the eruption exhibited some properties: ascending rapidly and descending slowly just like the process of the flare eruption. After the eruption, the most material in the prominence basically moved along a parabola under the action of magnetic force lines forming the arcade-like shape and keeping it till to the disappearance of the prominence. Before and after descending, a little matter came from the top part was ejected and divorced from the main body of the prominence and diffused into the interplanetary space.

  1. Predicting Major Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

    , whether an active region that produces a flare will also produce a CME. Bobra and Ilonidis then use a feature-selection algorithm to try to understand which features distinguish between flaring regions that dont produce a CME and those that do.Predictors of CMEsThe authors reach several interesting conclusions:Under the right conditions, their algorithm is able to predict whether an active region with a given set of features will produce a CME as well as a flare with a fairly high rate of success.None of the 18 features they tested are good predictors in isolation: its necessary to look at a combination of at least 6 features to have success predicting whether a flare will be accompanied by a CME.The features that are the best predictors are all intensive features ones that stay the same independent of the active regions size. Extensive features ones that change as the active region grows or shrinks are less successful predictors.Only the magnetic field properties of the photosphere were considered, so a logical next step is to extend this study to consider properties of the solar corona above active regions as well. In the meantime, these are interesting first results that may well help us better predict these major solar eruptions.BonusCheck out this video for a great description from NASA of the difference between solar flares and CMEs (as well as some awesome observations of both).CitationM. G. Bobra and S. Ilonidis 2016 ApJ 821 127. doi:10.3847/0004-637X/821/2/127

  2. Predictions of volcanic eruptions at Mt Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Ho, Chih-Hsiang

    1992-06-01

    We present a mathematically-based model for predicting the likelihood of future eruptions of Vesuvius and, by implication, other volcanoes. The volcanic activity of Vesuvius in the period 1630-1989 is described by a compound Poisson distribution with a gamma compounding density. The frequency distribution of eruptions in any given interval of equal length follows a negative binomial distribution (NBD). The assumptions of the NBD model are less restrictive, so the observation time can be extended to include the long repose following the 1944 eruption of Vesuvius. Moreover, this exceedingly flexible model has only two parameters which can be determined easily from the eruptive count data. The future probability of x number of eruptions is predicted on the aggregate behaviour of past volcanic activity. This capability would be useful for long-term planning, such as for land-use development, although not for short-term forecasts of volcanic hazards.

  3. 2014 Mount Ontake eruption: characteristics of the phreatic eruption as inferred from aerial observations

    NASA Astrophysics Data System (ADS)

    Kaneko, Takayuki; Maeno, Fukashi; Nakada, Setsuya

    2016-05-01

    The sudden eruption of Mount Ontake on September 27, 2014, led to a tragedy that caused more than 60 fatalities including missing persons. In order to mitigate the potential risks posed by similar volcano-related disasters, it is vital to have a clear understanding of the activity status and progression of eruptions. Because the erupted material was largely disturbed while access was strictly prohibited for a month, we analyzed the aerial photographs taken on September 28. The results showed that there were three large vents in the bottom of the Jigokudani valley on September 28. The vent in the center was considered to have been the main vent involved in the eruption, and the vents on either side were considered to have been formed by non-explosive processes. The pyroclastic flows extended approximately 2.5 km along the valley at an average speed of 32 km/h. The absence of burned or fallen trees in this area indicated that the temperatures and destructive forces associated with the pyroclastic flow were both low. The distribution of ballistics was categorized into four zones based on the number of impact craters per unit area, and the furthest impact crater was located 950 m from the vents. Based on ballistic models, the maximum initial velocity of the ejecta was estimated to be 111 m/s. Just after the beginning of the eruption, very few ballistic ejecta had arrived at the summit, even though the eruption plume had risen above the summit, which suggested that a large amount of ballistic ejecta was expelled from the volcano several tens-of-seconds after the beginning of the eruption. This initial period was characterized by the escape of a vapor phase from the vents, which then caused the explosive eruption phase that generated large amounts of ballistic ejecta via sudden decompression of a hydrothermal reservoir.

  4. Chain Reconnections Observed in Sympathetic Eruptions

    NASA Astrophysics Data System (ADS)

    Joshi, Navin Chandra; Schmieder, Brigitte; Magara, Tetsuya; Guo, Yang; Aulanier, Guillaume

    2016-04-01

    The nature of various plausible causal links between sympathetic events is still a controversial issue. In this work, we present multiwavelength observations of sympathetic eruptions, associated flares, and coronal mass ejections (CMEs) occurring on 2013 November 17 in two close active regions. Two filaments, i.e., F1 and F2, are observed in between the active regions. Successive magnetic reconnections, caused for different reasons (flux cancellation, shear, and expansion) have been identified during the whole event. The first reconnection occurred during the first eruption via flux cancellation between the sheared arcades overlying filament F2, creating a flux rope and leading to the first double-ribbon solar flare. During this phase, we observed the eruption of overlying arcades and coronal loops, which leads to the first CME. The second reconnection is believed to occur between the expanding flux rope of F2 and the overlying arcades of filament F1. We suggest that this reconnection destabilized the equilibrium of filament F1, which further facilitated its eruption. The third stage of reconnection occurred in the wake of the erupting filament F1 between the legs of the overlying arcades. This may create a flux rope and the second double-ribbon flare and a second CME. The fourth reconnection was between the expanding arcades of the erupting filament F1 and the nearby ambient field, which produced the bi-directional plasma flows both upward and downward. Observations and a nonlinear force-free field extrapolation confirm the possibility of reconnection and the causal link between the magnetic systems.

  5. Magma migration and resupply during the 1974 summit eruptions of Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Lockwood, John P.; Tilling, Robert I.; Holcomb, Robin T.; Klein, Fred W.; Okamura, Arnold T.; Peterson, Donald W.

    1999-01-01

    The purpose of this paper is to present a complete account of contrasting yet related eruptions, thus filling a gap in the published narratives of recent activity of Kilauea; and to examine their significance within a broader context of regional magmatic and eruptive dynamics. We have gained a historical perspective and can view these three eruptions within a multidecade context of the eruptive behavior of not only Kilauea, but also of the adjacent Mauna Loa.

  6. Driving Mechanism and Onset Condition of a Confined Eruption

    NASA Astrophysics Data System (ADS)

    Guo, Y.; Ding, M. D.; Schmieder, B.; Li, H.; Török, T.; Wiegelmann, T.

    2010-12-01

    We study a confined eruption accompanied by an M1.1 flare in solar active region (AR) NOAA 10767 on 2005 May 27, where a pre-eruptive magnetic flux rope was reported in a nonlinear force-free field (NLFFF) extrapolation. The observations show a strong writhing motion of the erupting structure, suggesting that a flux rope was indeed present and converted some of its twist into writhe in the course of the eruption. Using the NLFFF extrapolation, we calculate the twist of the pre-eruptive flux rope and find that it is in very good agreement with thresholds of the helical kink instability found in numerical simulations. We conclude that the activation and rise of the flux rope were triggered and driven by the instability. Using a potential field extrapolation, we also estimate the height distribution of the decay index of the external magnetic field in the AR 1 hr prior to the eruption. We find that the decay index stays below the threshold for the torus instability for a significant height range above the erupting flux rope. This provides a possible explanation for the confinement of the eruption to the low corona.

  7. Magma movements and Iceland's next eruptions (Invited)

    NASA Astrophysics Data System (ADS)

    Sigmundsson, F.; Ofeigsson, B.; Hreinsdottir, S.; Hensch, M.; Gudmundsson, G.; Vogfjord, K. S.; Roberts, M. J.; Geirsson, H.; La Femina, P. C.; Hooper, A. J.; Sturkell, E. C.; Einarsson, P.; Gudmundsson, M. T.; Brandsdottir, B.; Loughlin, S. C.; Team, F.

    2013-12-01

    Iceland, created by hotspot-ridge interaction, is characterized by higher magmatic input and more complicated plate boundary structure than other parts of the Mid-Atlantic rift system. It has 30+ volcanic systems, where 20 confirmed eruptions have occurred in the last 40 years, the most recent at Eyjafjallajökull in 2010 and Grimsvotn in 2011. Likely candidates for the next eruption include the four most active volcanoes in Iceland (Hekla, Katla, Grimsvotn, and Bardarbunga) and other areas of volcanic unrest (Askja region, the Krisuvik area). Present volcano monitoring and research, including the FUTUREVOLC project, aims at providing warnings of impending eruptions and their character. Earthquake monitoring and deformation studies have hereto provided the most relevant information. Hekla continuously accumulates magma at a rate of about 0.003-0.02 km3/yr, according to GPS and InSAR studies, in a magma chamber placed below 14 km depth. A sequence of M0.4-1 earthquakes early this year stands out from otherwise mostly aseismic character of Hekla during repose periods. The Hekla magma chamber does not fail at a constant amount of magma volume, rather a clear pattern is observed with eruption size scaling with the length of the preceding period of dormancy. The ice capped Katla volcano shows unusual annual deformation pattern, seismic activity, and hydrological variations depending on time of year, presumably related to ice load and water pressure variations. It may be in a critical stage and renewed inflow of magma may quickly move the volcano towards failure. Bardarbunga had major earthquake and magma transfer activity in 1996, and has been the site of deep low-frequency earthquakes. Grímsvötn volcano is the only volcano with a shallow magma chamber with ongoing confirmed recharging, and failure criteria closest to 'expected'. A large eruption occurred in 2011 compared to much smaller eruption in 2004. However, the amount of erupted magma did not scale with the

  8. Probabilities of future VEI ≥ 2 eruptions at the Central American Volcanic Arc: a statistical perspective based on the past centuries' eruption record

    NASA Astrophysics Data System (ADS)

    Dzierma, Yvonne; Wehrmann, Heidi

    2014-10-01

    A probabilistic eruption forecast is provided for seven historically active volcanoes along the Central American Volcanic Arc (CAVA), as a pivotal empirical contribution to multi-disciplinary volcanic hazards assessment. The eruption probabilities are determined with a Kaplan-Meier estimator of survival functions, and parametric time series models are applied to describe the historical eruption records. Aside from the volcanoes that are currently in a state of eruptive activity (Santa María, Fuego, and Arenal), the highest probabilities for eruptions of VEI ≥ 2 occur at Concepción and Cerro Negro in Nicaragua, which are likely to erupt to 70-85 % within the next 10 years. Poás and Irazú in Costa Rica show a medium to high eruption probability, followed by San Miguel (El Salvador), Rincón de la Vieja (Costa Rica), and Izalco (El Salvador; 24 % within the next 10 years).

  9. Textural constraints on the dynamics of the 2000 Miyakejima eruption

    NASA Astrophysics Data System (ADS)

    Garozzo, Ileana; Romano, Claudia; Giordano, Guido; Geshi, Nobuo; Vona, Alessandro

    2016-04-01

    Miyakejima Volcano is a basaltic-andesite stratovolcano active from ~10.000 years, located on the north of the Izu-Bonin arc. During the last 600 years the volcano has been characterized mainly by flank fissure activity, with explosive phreatomagmatic eruptions on the coastal areas. In the last century, the activity became more frequent and regular with intervals of 20 to 70 years (1940, 1962, 1983 and 2000). The last activity started on 27 June 2000, with a minor submarine eruption on the west coast of the volcano, and proceeded with six major summit eruptions from July 8 to August 29. The eruptions led to the formation of a collapse caldera ~1.6 km across. The total erupted tephra represents only 1.7% in volume of the caldera, the high fragmentation of magma produced mainly fine-grained volcanic ash. In order to improve the understanding on the triggering and dynamics of this explosive eruption, we carried out a detailed investigation of the erupted materials with particular attention to the textural features of juvenile pyroclasts (Vesicle and Crystal Size Distributions). The stratigraphic record can be divided into six fall units, corresponding to the six summit eruptions, although juvenile materials were identified only in 4 units (unit 2, 4, 5, 6). We selected about 100 juvenile grains sampled from the bottom to the top of each level, to be analyzed by scanning electron microscopy. The study of juvenile morphological features allowed us to recognize the existence of three characteristic morphotypes, showing marked differences in their external morphologies and internal textures (from poorly to highly crystallized and vesiculated clasts). The distribution of these morphotypes is non-homogeneous along the eruptive sequence indicating changes of dynamics during magma ascent. Juveniles do not show features inherited from the interaction with external water. Vesicle Volume Distributions of the selected ash grains show that the three types of pyroclasts experienced

  10. Introduction to the 2012-2013 Tolbachik eruption special issue

    NASA Astrophysics Data System (ADS)

    Edwards, Benjamin R.; Belousov, Alexander; Belousova, Marina; Volynets, Anna

    2015-12-01

    The Tolbachik volcanic complex in central Kamchatka holds a special place in global volcanological studies. It is one of 4 areas of extensive historic volcanic activity in the northern part of the Central Kamchatka Depression (the others being Klyuchevskoy, Bezymianny, Shiveluch), and is part of the Klyuchevskoy volcanic group, which is one of the most active areas of volcanism on Earth. Tolbachik is especially well-known due largely to the massive 1975-1976 eruption that became known as the Great Tolbachik Fissure eruption (GTFE; Fedotov, 1983; Fedotov et al., 1984). This was one of the first eruptions in Russia to be predicted based on precursory seismic activity, based on M5 earthquakes approximately one week before the eruption started, and was intensively studied during its course by a large number of Russian scientists. A summary of those studies was published, first in Russian and then in English, and it became widely read for many reasons. One in particular is that the eruption was somewhat unusual for a subduction zone setting; although many subduction zone stratovolcanoes have associated basaltic tephra cone-lava fields, this was the first such Hawaiian-style eruption to be widely observed. After the end of the eruption in 1976, the complex showed no signs of activity until 27 November 2012, when increased seismic activity was registered by the Kamchatka Branch of the Russian Geophysical Survey and a red glow from the eruption site was first noticed through the snowstorm haze. This prompted them, and then the Kamchatka Volcanic Emergency Response Team (KVERT) to issue an alert that activity was coming from the south flank of Plosky Tolbachik volcano, the younger of two volcanic edifices (the older is Ostry Tolbachik) that together make up the bulk of the complex along with tephra cone-lava fields that lie along a NE-SW fissure zone that transects Plosky Tolbachik. The new eruption lasted for more than 250 days and, like the 1975-1976 eruption, was

  11. The feeder system for the 2014 fissure eruption at Holuhraun, Bárðarbunga volcanic system, Iceland: Geodetic and seismic constraints on subsurface activity in the area north of the Vatnajökull ice cap

    NASA Astrophysics Data System (ADS)

    Dumont, Stéphanie; Parks, Michelle; Sigmundsson, Freysteinn; Hooper, Andy; Hreinsdóttir, Sigrun; Ófeigsson, Benedikt; Spaans, Karsten; Vogfjörd, Kristin; Jónsdóttir, Kristín; Hensch, Martin; Gudmundsson, Gunnar; Rafn Heimisson, Elias; Drouin, Vincent; Árnadóttir, Thóra; Pedersen, Rikke; Rut Hjartardóttir, Ásta; Magnússon, Eyjólfur

    2015-04-01

    An intense earthquake swarm began on 16 August 2014 at Bárðarbunga volcano under the Vatnajökull ice cap in Central Iceland. It marked the beginning of an intrusive activity, with a dyke propagating over 45 km northward. Such major magmatic activity has not been observed for the last three decades in Iceland, since the Krafla rifting episode 1975-1984. The dyke propagation stopped 15 days after the onset of the seismic activity, with the dyke distal end in the Holuhraun plain north of the Vatnajökull ice cap. A small 4 hour eruption marked the beginning of extrusive activity. A new fissure eruption opened up on 31 August at the northern dyke tip, with lava fountaining and feeding extensive lava flows. In January 2014 the surface covered by the lava had exceeded 80 km2, and the eruption activity does not show significant decline. We have carried out interferometric analysis of SAR data (InSAR) since the onset of the unrest. X-band satellite images from COSMO-SkyMed and TerraSAR-X satellites were acquired and analyzed to map ground surface deformation associated with the dyke emplacement. Despite most of the dyke propagation occurring under several hundreds meters of ice, the last 10 km were outside the ice cap, allowing better characterisation of the dyke-induced deformation. Here we focus on the deformation in the Holuhraun plain, in order to better understand the link between the surface deformation detected in the vicinity of the dyke by InSAR as well as GPS measurements, and the eruptive activity. The regular SAR acquisitions made over the Holuhraun area since the beginning of the unrest offer a unique opportunity to better understand the evolution of the intrusion feeding the fissure eruption. For that purpose, we focus on the faults and fissures forming the graben borders on the glacier as well as in the Holuhraun plain, initially mapped using high-resolution radar images, acquired by airborne radar. We extract movement along and perpendicular to these

  12. Nyamuragira Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nyamuragira volcano erupted on July 26, 2002, spewing lava high into the air along with a large plume of steam, ash, and sulfur dioxide. The 3,053-meter (10,013-foot) volcano is located in eastern Congo, very near that country's border with Rwanda. Nyamuragira is the smaller, more violent sibling of Nyiragongo volcano, which devastated the town of Goma with its massive eruption in January 2002. Nyamuragira is situated just 40 km (24 miles) northeast of Goma. This true-color image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on July 28, 2002. Nyamuragira is situated roughly in the center of this scene, roughly 100 km south of Lake Edward and just north of Lake Kivu (which is mostly obscured by the haze from the erupting volcano and the numerous fires burning in the surrounding countryside). Due south of Lake Kivu is the long, narrow Lake Tanganyika running south and off the bottom center of this scene.

  13. ROTATION OF CORONAL MASS EJECTIONS DURING ERUPTION

    SciTech Connect

    Lynch, B. J.; Li, Y.; Luhmann, J. G.; Antiochos, S. K.; DeVore, C. R. E-mail: yanli@ssl.berkeley.edu E-mail: spiro.k.antiochos@nasa.gov

    2009-06-01

    Understanding the connection between coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs) is one of the most important problems in solar-terrestrial physics. We calculate the rotation of erupting field structures predicted by numerical simulations of CME initiation via the magnetic breakout model. In this model, the initial potential magnetic field has a multipolar topology and the system is driven by imposing a shear flow at the photospheric boundary. Our results yield insight on how to connect solar observations of the orientation of the filament or polarity inversion line (PIL) in the CME source region, the orientation of the CME axis as inferred from coronagraph images, and the ICME flux rope orientation obtained from in situ measurements. We present the results of two numerical simulations that differ only in the direction of the applied shearing motions (i.e., the handedness of the sheared-arcade systems and their resulting CME fields). In both simulations, eruptive flare reconnection occurs underneath the rapidly expanding sheared fields transforming the ejecta fields into three-dimensional flux rope structures. As the erupting flux ropes propagate through the low corona (from 2 to 4 R{sub sun}) the right-handed breakout flux rope rotates clockwise and the left-handed breakout flux rope rotates counterclockwise, in agreement with recent observations of the rotation of erupting filaments. We find that by 3.5 R {sub sun} the average rotation angle between the flux rope axes and the active region PIL is approximately 50 deg. We discuss the implications of these results for predicting, from the observed chirality of the pre-eruption filament and/or other properties of the CME source region, the direction and amount of rotation that magnetic flux rope structures will experience during eruption. We also discuss the implications of our results for CME initiation models.

  14. Mid-ocean ridge eruptions as a climate valve

    NASA Astrophysics Data System (ADS)

    Tolstoy, Maya

    2015-03-01

    Seafloor eruption rates and mantle melting fueling eruptions may be influenced by sea level and crustal loading cycles at scales from fortnightly to 100 kyr. Recent mid-ocean ridge eruptions occur primarily during neap tides and the first 6 months of the year, suggesting sensitivity to minor changes in tidal forcing and orbital eccentricity. An ~100 kyr periodicity in fast-spreading seafloor bathymetry and relatively low present-day eruption rates at a time of high sea level and decreasing orbital eccentricity suggest a longer-term sensitivity to sea level and orbital variations associated with Milankovitch cycles. Seafloor spreading is considered a small but steady contributor of CO2 to climate cycles on the 100 kyr time scale; however, this assumes a consistent short-term eruption rate. Pulsing of seafloor volcanic activity may feed back into climate cycles, possibly contributing to glacial/interglacial cycles, the abrupt end of ice ages, and dominance of the 100 kyr cycle.

  15. Driving mechanism of a failed eruption

    NASA Astrophysics Data System (ADS)

    Guo, Y.; Ding, M. D.; Schmieder, B.; Li, H.; Törö, T.; Wiegelmann, T.

    We find a magnetic flux rope before the M1.1 flare in active region 10767 on 2005 May 27 by a nonlinear force-free field extrapolation. TRACE observations of the filament eruption show that the erupting structure performed a writhing deformation and stopped rising at a certain height, suggesting that the flux rope converted some of its twist into writhe and was confined in the corona. After calculating the twist of the flux rope, we find that it was comparable to thresholds of the helical kink instability found in numerical simulations. We conclude that the activation and rise of the flux rope were triggered and initially driven by the kink instability. The decay index of the external magnetic field stays below the threshold for the torus instability within a long height range. The confinement of the eruption could be explained by the failure of the torus instability. Hard X-ray sources at the peak of the M1.1 flare coincided with the footpoints of the erupting helical structure, which indicates a high possibility that hard X-ray sources were produced more efficiently in the flux rope.

  16. Rheological controls on the eruption style and size of historical eruptions from Mt. Ruapehu, New Zealand

    NASA Astrophysics Data System (ADS)

    Kilgour, Geoff; Mader, Heidy

    2014-05-01

    The physical state of a magma controls a range of igneous processes, from crystal and bubble growth, the ability to exsolve gas, drive convection, and eventually whether the magma erupts or stalls. During magma ascent, crystallisation and bubble expansion significantly alter the physical state of a magma. Therefore, a quantitative assessment of magma rheology through time could help to explain the style, duration and size of eruptions. The aim of this work is to determine the rheology of magma from storage to eruption using existing constitutive equations. An assessment of the changing rheological properties of magma could provide insights into the generation of seismicity, deformation, and gas efflux; all signals that are regularly monitored at active volcanoes. Regular eruptions have occurred at Mt. Ruapehu, New Zealand since 1830, yet all have been small volume (< 0.001 km3). This work combines melt inclusion volatile contents with geochemistry to track the physical state of the magma from its source region (300 MPa) to eruption. In doing so, we hoped to explain the size and style of Ruapehu eruptions. The rheology of Ruapehu magma has been determined using a combination of thermodynamic models and rheological calculations. We used a thermodynamic model (MELTS) to determine the composition of three, representative Ruapehu magmas from 300 MPa to ~ 30 MPa. The outputs of the model agreed with experimental data and provided the crystal and bubble (assuming no gas loss) content, along with the melt content and composition. We calculated the melt viscosity, and the relative effect of bubbles and crystals, to quantify the rheology of the magma during ascent (under assumed equilibrium conditions). The crystal content at which a yield strength would develop, and therefore the point at which a magma would likely stall, has been constrained to ~ 0.3, which is marginally higher than the crystal content of erupted scoria. Historical eruptions from Ruapehu were H2O

  17. Models of volcanic eruption hazards

    SciTech Connect

    Wohletz, K.H.

    1992-01-01

    Volcanic eruptions pose an ever present but poorly constrained hazard to life and property for geothermal installations in volcanic areas. Because eruptions occur sporadically and may limit field access, quantitative and systematic field studies of eruptions are difficult to complete. Circumventing this difficulty, laboratory models and numerical simulations are pivotal in building our understanding of eruptions. For example, the results of fuel-coolant interaction experiments show that magma-water interaction controls many eruption styles. Applying these results, increasing numbers of field studies now document and interpret the role of external water eruptions. Similarly, numerical simulations solve the fundamental physics of high-speed fluid flow and give quantitative predictions that elucidate the complexities of pyroclastic flows and surges. A primary goal of these models is to guide geologists in searching for critical field relationships and making their interpretations. Coupled with field work, modeling is beginning to allow more quantitative and predictive volcanic hazard assessments.

  18. Estimating rates of decompression from textures of erupted ash particles produced by 1999-2006 eruptions of Tungurahua volcano, Ecuador

    USGS Publications Warehouse

    Wright, Heather M.N.; Cashman, Katharine V.; Mothes, Patricia A.; Hall, Minard L.; Ruiz, Andrés Gorki; Le Pennec, Jean-Luc

    2012-01-01

    Persistent low- to moderate-level eruptive activity of andesitic volcanoes is difficult to monitor because small changes in magma supply rates may cause abrupt transitions in eruptive style. As direct measurement of magma supply is not possible, robust techniques for indirect measurements must be developed. Here we demonstrate that crystal textures of ash particles from 1999 to 2006 Vulcanian and Strombolian eruptions of Tungurahua volcano, Ecuador, provide quantitative information about the dynamics of magma ascent and eruption that is difficult to obtain from other monitoring approaches. We show that the crystallinity of erupted ash particles is controlled by the magma supply rate (MSR); ash erupted during periods of high magma supply is substantially less crystalline than during periods of low magma supply. This correlation is most easily explained by efficient degassing at very low pressures (<<50 MPa) and degassing-driven crystallization controlled by the time available prior to eruption. Our data also suggest that the observed transition from intermittent Vulcanian explosions at low MSR to more continuous periods of Strombolian eruptions and lava fountains at high MSR can be explained by the rise of bubbles through (Strombolian) or trapping of bubbles beneath (Vulcanian) vent-capping, variably viscous (and crystalline) magma.

  19. Solar filament material oscillations and drainage before eruption

    SciTech Connect

    Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Hong, Junchao; Li, Haidong; Yang, Dan; Yang, Bo

    2014-08-01

    Both large-amplitude longitudinal (LAL) oscillations and material drainage in a solar filament are associated with the flow of material along the filament axis, often followed by an eruption. However, the relationship between these two motions and a subsequent eruption event is poorly understood. We analyze a filament eruption using EUV imaging data captured by the Atmospheric Imaging Array on board the Solar Dynamics Observatory and the Hα images from the Global Oscillation Network Group. Hours before the eruption, the filament was activated, with one of its legs undergoing a slow rising motion. The asymmetric activation inclined the filament relative to the solar surface. After the active phase, LAL oscillations were observed in the inclined filament. The oscillation period increased slightly over time, which may suggest that the magnetic fields supporting the filament evolve to be flatter during the slow rising phase. After the oscillations, a significant amount of filament material was drained toward one filament endpoint, followed immediately by the violent eruption of the filament. The material drainage may further support the change in magnetic topology prior to the eruption. Moreover, we suggest that the filament material drainage could play a role in the transition from a slow to a fast rise of the erupting filament.

  20. Erupted complex odontoma delayed eruption of permanent molar.

    PubMed

    Ohtawa, Yumi; Ichinohe, Saori; Kimura, Eri; Hashimoto, Sadamitsu

    2013-01-01

    Odontomas, benign tumors that develop in the jaw, rarely erupt into the oral cavity. We report an erupted odontoma which delayed eruption of the first molar. The patient was a 10-year-old Japanese girl who came to our hospital due to delayed eruption of the right maxillary first molar. All the deciduous teeth had been shed. The second premolar on the right side had erupted, but not the first molar. Slight inflammation of the alveolar mucosa around the first molar had exposed a tooth-like, hard tissue. Panoramic radiography revealed a radiopaque mass indicating a lesion approximately 1 cm in diameter. The border of the image was clear, and part of the mass was situated close to the occlusal surface of the first molar. The root of the maxillary right first molar was only half-developed. A clinical diagnosis of odontoma was made. The odontoma was subsequently extracted, allowing the crown of the first molar to erupt almost 5 months later. The dental germ of the permanent tooth had been displaced by the odontoma. However, after the odontoma had been extracted, the permanent tooth was still able to erupt spontaneously, as eruptive force still remained. When the eruption of a tooth is significantly delayed, we believe that it is necessary to examine the area radiographically. If there is any radiographic evidence of a physical obstruction that might delay eruption, that obstruction should be removed before any problems can arise. Regular dental checkups at schools might improve our ability to detect evidence of delayed eruption earlier. PMID:24521551

  1. New Aspects of a Lid-Removal Mechanism in the Onset of a SEP-Producing Eruption Sequence

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Knox, Javon M.

    2014-01-01

    We examine a sequence of two ejective eruptions from a single active region on 2012 January 23, using magnetograms and EUV images from SDO/HMI and SDO/AIA, and EUV images from STEREO. Cheng et al. (2013) showed that the first eruption's ("Eruption 1'') flux rope was apparent only in "hotter'' AIA channels, and that it removed overlying field that allowed the second eruption (``Eruption 2'') to begin via ideal MHD instability; here we say Eruption 2 began via a ``lid removal'' mechanism. We show that during Eruption-1's onset, its flux rope underwent ``tether weakening'' (TW) reconnection with the field of an adjacent active region. Standard flare loops from Eruption 1 developed over Eruption-2's flux rope and enclosed filament, but these overarching new loops were unable to confine that flux rope/filament. Eruption-1's flare loops, from both TW reconnection and standard-flare-model internal reconnection, were much cooler than Eruption-2's flare loops (GOES thermal temperatures of approx. 9 MK compared to approx. 14 MK). This eruption sequence produced a strong solar energetic particle (SEP) event (10 MeV protons, >10(exp 3) pfu for 43 hrs), apparently starting when Eruption-2's CME blasted through Eruption-1's CME at 5-10 R_s. This occurred because the two CMEs originated in close proximity and in close time sequence: Eruption-1's fast rise started soon after the TW reconnection; the lid removal by Eruption-1's ejection triggered the slow onset of Eruption 2; and Eruption-2's CME, which started approx. 1 hr later, was three times faster than Eruption-1's CME.

  2. Eruptive history of the youngest Mexican Shield and Mexico's most voluminous Holocene eruption: Cerro El Metate

    NASA Astrophysics Data System (ADS)

    Oryaëlle Chevrel, Magdalena; Guilbaud, Marie-Noelle; Siebe, Claus

    2016-04-01

    Small to medium-sized shield volcanoes are an important component of many volcanic fields on Earth. The Trans-Mexican Volcanic Belt, one of the most complex and active continental arcs worldwide, displays a large number of such medium-sized volcanoes. In particular the Michoacán-Guanajuato Volcanic Field (MGVF) situated in central Mexico, is the largest monogenetic volcanic field in the world and includes more than 1000 scoria cones and about four hundred medium-sized volcanoes, also known as Mexican shields. The Mexican shields nevertheless represent nearly 70% of the total volume erupted since 1 Ma and hence played a considerable role in the formation of the MGVF. However, the source, storage, and transport as well as the physical properties (density, viscosity, volatile content, etc.) of the magmas involved in these eruptions remain poorly constrained. Here, we focus on Cerro El Metate, the youngest monogenetic andesite shield volcano of the field. New C14 dates for the eruption yield a young age (~AD 1250), which briefly precedes the initial rise of the Tarascan Empire (AD 1350-1521) in this region. This volcano has a minimum volume of ~9.2 km3 DRE, and its viscous lava flows were emplaced during a single eruption over a period of ~35 years covering an area of 103 km2. By volume, this is certainly the largest eruption during the Holocene in Mexico, and it is the largest andesitic effusive eruption known worldwide for this period. Such a large volume of lava erupted in a relatively short time had a significant impact on the environment (modification of the hydrological network, forest fires, etc.), and hence, nearby human populations probably had to migrate. Its eruptive history was reconstructed through detailed mapping, and geochemical and rheological analyses of its thick hornblende-bearing andesitic flows. Early and late flows have distinct morphologies, chemical and mineralogical compositions, and isotopic signatures which show that these lavas were fed by

  3. Granulomatous Drug Eruptions.

    PubMed

    Dodiuk-Gad, Roni P; Shear, Neil H

    2015-07-01

    Granuloma formation is usually regarded as a means of defending the host from persistent irritants of either exogenous or endogenous origin. Noninfectious granulomatous disorders of the skin encompass a challenging group of diseases owing to their clinical and histologic overlap. Drug reactions characterized by a granulomatous reaction pattern are rare, and defined by a predominance of histiocytes in the inflammatory infiltrate. This review summarizes current knowledge on the various types of granulomatous drug eruptions, focusing on the 4 major types: interstitial granulomatous drug reaction, drug-induced accelerated rheumatoid nodulosis, drug-induced granuloma annulare, and drug-induced sarcoidosis. PMID:26143430

  4. Comparison of Galunggung1982-83 and Eyjafjalla-2010 Eruptions: definition of eruption dynamics from 3D Ash Surface Morphology

    NASA Astrophysics Data System (ADS)

    Aydar, E.; Höskuldsson, A.; Ersoy, O.; Gourgaud, A.

    2012-04-01

    fragmentation mechanisms. Several common types of ashes produced during phreatomagmatic fragmentation process bear blocky-equant, mosslike, plate-like and drop or spherical shapes, besides, magmatic fragmentation leads to the formation of vesiculated fragments. We applied some quantitative statistical parameters for surface descriptors of volcanic ashes such as "Average roughness of profile (Ra), Maximum valley height of roughness profile (Rv), profile irregularities of roughness profile, Surface Area (SA), Volume (V), Fractal Dimension of Roughness (DAS)". We compared quantitative morphological data acquired from both eruptions. The grain size distribution of Eyjafjalla-2010 eruption, ash surface morphology, tephras types and textural parameters exhibit that magma input was important during the first phase (14-16 April) than following days. First phase ashes have either tubular vesicles as classically known for plinian deposits or curviplanar cut vesicles and some brittle fracturations, characteristics of phreatomagmatism. Interestingly, coarse fragmentation happened after the first phase. There is great similarities between two eruptions, but in reverse sens that in Galunggung, the eruption started with vulcanian style then phreatomatism and lasted with strombolian activity. Besides in Eyjafjalla-2010, eruptive phase started with basaltic activities at the North, then phreatomagmatism and toward the end a slight vulcanian style happened.

  5. Mafic intrusions triggering eruptions in Iceland

    NASA Astrophysics Data System (ADS)

    Sigmarsson, O.

    2012-04-01

    The last two eruptions in Iceland, Eyjafjallajökull 2010 and Grímsvötn 2011, were both provoked by an intrusion of more mafic magma into pre-existing magmatic system. Injection into the latter volcano, which is located in the main rift-zone of the island, above the presumed centre of the mantle plume and is the most active volcano of Iceland, has been gradual since the last eruption in 2004. In contrast, at Eyjafjallajökull volcano, one of the least active volcano in Iceland and located at the southern part of a propagating rift-zone where extensional tectonics are poorly developed, mafic magma intrusion occurred over less than a year. Beneath Eyjafjallajökull, a silicic intrusion at approximately 6 km depth was recharged with mantle derived alkali basalt that was injected into residual rhyolite from the penultimate eruption in the years 1821-23. The resulting magma mingIing process was highly complex, but careful sampling of tephra during the entire eruption allows the dynamics of the mingling process to be unravelled. Short-lived disequilibria between the gaseous nuclide 210Po and the much less volatile nuclide 210Pb, suggest that basalt accumulated beneath the silicic intrusion over approximately 100 days, or from early January 2010 until the onset of the explosive summit eruption on 14 April. Due to the degassing, crystal fractionation modified the composition of the injected mafic magma producing evolved Fe-and Ti-rich basalt, similar in composition to that of the nearby Katla volcano. This evolved basalt was intruded into the liquid part of the silicic intrusion only a few hours before the onset of the explosive summit eruption. The short time between intrusion and eruption led to the production of very heterogeneous (of basaltic, intermediate and silicic composition) and fine-grained tephra during the first days of explosive eruption. The fine grained tephra resulted from combined effects of magma fragmentation due to degassing of stiff magma rich in

  6. Ionospheric effects of the Mt. Kirishima volcanic eruption as seen from subionospheric VLF observations

    NASA Astrophysics Data System (ADS)

    Rozhnoi, A.; Hayakawa, M.; Solovieva, M.; Hobara, Y.; Fedun, V.

    2014-01-01

    Data from the Pacific network of VLF receivers have been used to study the response of the lower ionosphere to the January 2011 Mt. Kirishima (South Japan) volcanic eruption. A major explosive eruption occurred on January 27, which was preceded by several small eruptions. Perturbations of nighttime subionospheric VLF signals have been detected on the day of the first small eruption on January 18 (UT) with the maximum observed about 1.5 h after the eruption. The nighttime signal remained disturbed during the subsequent pre-eruptive and eruptive activity of Mt. Kirishima. The daytime perturbations were not observed. The frequency of the maximum spectral amplitude was found to be in the range of periods of 6-30 min, which corresponds to the periods of internal gravity waves. These results suggest that the observed VLF ionospheric effects can possibly be produced by the penetration of gravity waves caused by the volcanic activity into the ionosphere.

  7. ERUPTION OF A SOLAR FILAMENT CONSISTING OF TWO THREADS

    SciTech Connect

    Bi Yi; Jiang Yunchun; Li Haidong; Hong Junchao; Zheng Ruisheng E-mail: jyc@ynao.ac.cn

    2012-10-10

    The trigger and driving mechanism for the eruption of a filament consisting of two dark threads was studied with unprecedented high cadence and resolution of He II 304 A observations made by the Atmospheric Imagining Assembly (AIA) on board the Solar Dynamics Observatory (SDO) and the observations made by the Solar Magnetic Activity Research Telescope and the Extreme Ultraviolet Imager (EUVI) telescope on board the Solar Terrestrial Relations Observatory Ahead (STEREO-A). The filament was located at the periphery of the active region NOAA 11228 and erupted on 2011 June 6. At the onset of the eruption, a turbulent filament thread was found to be heated and to elongate in stride over a second one. After it rose slowly, most interestingly, the elongating thread was driven to contact and interact with the second one, and it then erupted with its southern leg being wrapped by a newly formed thread produced by the magnetic reconnection between fields carried by the two threads. Combining the observations from STEREO-A/EUVI and SDO/AIA 304 A images, the three-dimensional shape of the axis of the filament was obtained and it was found that only the southern leg of the eruptive filament underwent rotation. We suggest that the eruption was triggered by the reconnection of the turbulent filament thread and the surrounding magnetic field, and that it was mainly driven by the kink instability of the southern leg of the eruptive filament that possessed a more twisted field introduced by the reconnection-produced thread.

  8. Steam explosions, earthquakes, and volcanic eruptions -- what's in Yellowstone's future?

    USGS Publications Warehouse

    Lowenstern, Jacob B.; Christiansen, Robert L.; Smith, Robert B.; Morgan, Lisa A.; Heasler, Henry

    2005-01-01

    Yellowstone, one of the world?s largest active volcanic systems, has produced several giant volcanic eruptions in the past few million years, as well as many smaller eruptions and steam explosions. Although no eruptions of lava or volcanic ash have occurred for many thousands of years, future eruptions are likely. In the next few hundred years, hazards will most probably be limited to ongoing geyser and hot-spring activity, occasional steam explosions, and moderate to large earthquakes. To better understand Yellowstone?s volcano and earthquake hazards and to help protect the public, the U.S. Geological Survey, the University of Utah, and Yellowstone National Park formed the Yellowstone Volcano Observatory, which continuously monitors activity in the region.

  9. Evidence for different eruptive conditions for two simultaneous, late Miocene, rhyolitic phreatomagmatic eruptions: Jemez Mountains, New Mexico

    SciTech Connect

    Gay, K.R.; Smith, G.A. . Dept. of Earth and Planetary Sciences)

    1993-04-01

    The Peralta Tuff Member of the Bearhead Rhyolite records episodic, rhyolitic volcanism during the late Miocene. It is composed of primary and reworked pyroclastic-flow (PF), tephra-fall (TF), and pyroclastic-surge (PS) deposits intercalated with braided-stream deposits. Two eruptive units have been informally named the Tuffs of West Mesa (TWM) and the Tuffs of Lower Peralta Canyon (TLPC). The TWM consist of 20 m of PF and minor PS deposits erupted from a vent in the Bearhead Park dome complex. In most places the TLPC consist of 50 m of PF, PS, and TF and were erupted from a vent located 7 km SE of Bearhead Peak. The absence of inter-eruptive sediments, erosional surfaces, or paleosols, along with the intercalated nature of the two units, indicates that the two eruptions were simultaneous. Granulometric, vesiculation, petrographic, and stratigraphic data indicate that the TWM eruption began with a phreatomagmatic (PM) component, resulting in the formation of a tuff ring at least 70 m thick, and ended with [ge]20 m of drier PF that traveled at least 6 km from the vent. The TLPC eruption began with several PM eruptive cycles of wet, ash-rich, low-angle x-bedded PS to drier, pumiceous, lapilli-rich PS. Abundant fragments of underlying rift-fill sediments decrease upward in the cycles. The cyclic deposits were followed by 20 m of pumice-rich, x-bedded PS, containing only rare sedimentary fragments. The TLPC eruption concluded with a 2 m TF. The greater phreatomagmatic component to the TLPC eruption, despite its proximity to the simultaneously active TWM vent, is apparently related to the mixing of magma with basin-fill sediments at a topographically lower ([ge]300 m) position and at a site that probably has less subjacent, relatively dry, older volcanic rocks.

  10. Drug Rash (Unclassified Drug Eruption) in Children

    MedlinePlus

    ... rash and rashes clinical tools newsletter | contact Share | Drug Eruption, Unclassified (Pediatric) A parent's guide to condition ... lesions coming together into larger lesions typical of drug rashes (eruptions). Overview A drug eruption, also known ...

  11. Nyamuragira Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nyamuragira volcano erupted on July 26, 2002, spewing lava high into the air along with a large plume of steam, ash, and sulfur dioxide. The 3,053-meter (10,013-foot) volcano is located in eastern Congo, very near that country's border with Rwanda. Nyamuragira is the smaller, more violent sibling of Nyiragongo volcano, which devastated the town of Goma with its massive eruption in January 2002. Nyamuragira is situated just 40 km (24 miles) northeast of Goma. This pair of images was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on July 26. The image on the left shows the scene in true color. The small purple box in the upper righthand corner marks the location of Nyamuragira's hot summit. The false-color image on the right shows the plume from the volcano streaming southwestward. This image was made using MODIS' channels sensitive at wavelengths from 8.5 to 11 microns. Red pixels indicate high concentrations of sulphur dioxide. Image courtesy Liam Gumley, Space Science and Engineering Center, University of Wisconsin-Madison

  12. The physics of large eruptions

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust

    2015-04-01

    Based on eruptive volumes, eruptions can be classified as follows: small if the volumes are from less than 0.001 km3 to 0.1 km3, moderate if the volumes are from 0.1 to 10 km3, and large if the volumes are from 10 km3 to 1000 km3 or larger. The largest known explosive and effusive eruptions have eruptive volumes of 4000-5000 km3. The physics of small to moderate eruptions is reasonably well understood. For a typical mafic magma chamber in a crust that behaves as elastic, about 0.1% of the magma leaves the chamber (erupted and injected as a dyke) during rupture and eruption. Similarly, for a typical felsic magma chamber, the eruptive/injected volume during rupture and eruption is about 4%. To provide small to moderate eruptions, chamber volumes of the order of several tens to several hundred cubic kilometres would be needed. Shallow crustal chambers of these sizes are common, and deep-crustal and upper-mantle reservoirs of thousands of cubic kilometres exist. Thus, elastic and poro-elastic chambers of typical volumes can account for small to moderate eruptive volumes. When the eruptions become large, with volumes of tens or hundreds of cubic kilometres or more, an ordinary poro-elastic mechanism can no longer explain the eruptive volumes. The required sizes of the magma chambers and reservoirs to explain such volumes are simply too large to be plausible. Here I propose that the mechanics of large eruptions is fundamentally different from that of small to moderate eruptions. More specifically, I suggest that all large eruptions derive their magmas from chambers and reservoirs whose total cavity-volumes are mechanically reduced very much during the eruption. There are two mechanisms by which chamber/reservoir cavity-volumes can be reduced rapidly so as to squeeze out much of, or all, their magmas. One is piston-like caldera collapse. The other is graben subsidence. During large slip on the ring-faults/graben-faults the associated chamber/reservoir shrinks in volume

  13. WOVOdat as a worldwide resource to improve eruption forecasts

    NASA Astrophysics Data System (ADS)

    Widiwijayanti, Christina; Costa, Fidel; Zar Win Nang, Thin; Tan, Karine; Newhall, Chris; Ratdomopurbo, Antonius

    2015-04-01

    During periods of volcanic unrest, volcanologists need to interpret signs of unrest to be able to forecast whether an eruption is likely to occur. Some volcanic eruptions display signs of impending eruption such as seismic activity, surface deformation, or gas emissions; but not all will give signs and not all signs are necessarily followed by an eruption. Volcanoes behave differently. Precursory signs of an eruption are sometimes very short, less than an hour, but can be also weeks, months, or even years. Some volcanoes are regularly active and closely monitored, while other aren't. Often, the record of precursors to historical eruptions of a volcano isn't enough to allow a forecast of its future activity. Therefore, volcanologists must refer to monitoring data of unrest and eruptions at similar volcanoes. WOVOdat is the World Organization of Volcano Observatories' Database of volcanic unrest - an international effort to develop common standards for compiling and storing data on volcanic unrests in a centralized database and freely web-accessible for reference during volcanic crises, comparative studies, and basic research on pre-eruption processes. WOVOdat will be to volcanology as an epidemiological database is to medicine. We have up to now incorporated about 15% of worldwide unrest data into WOVOdat, covering more than 100 eruption episodes, which includes: volcanic background data, eruptive histories, monitoring data (seismic, deformation, gas, hydrology, thermal, fields, and meteorology), monitoring metadata, and supporting data such as reports, images, maps and videos. Nearly all data in WOVOdat are time-stamped and geo-referenced. Along with creating a database on volcanic unrest, WOVOdat also developing web-tools to help users to query, visualize, and compare data, which further can be used for probabilistic eruption forecasting. Reference to WOVOdat will be especially helpful at volcanoes that have not erupted in historical or 'instrumental' time and

  14. The Puu Oo eruption of Kilauea Volcano, Hawaii

    SciTech Connect

    Wolfe, E.W. )

    1988-01-01

    The Puu Oo eruption is the most voluminous and longest-lived historical flank eruption of Kilauea volcano. A pattern of episodic lava discharge developed in which relatively brief periods of vigorous fountaining and high-volume flow production alternated with longer repose periods. The activity was intensely monitored, and results of the first 11/2 yrs of observation and measurement are reported, including geologic observations, lava sampling, temperature measurements, compositional analyses, petrologic study, studies of gas composition and the role of gases in the eruptive process, geodetic measurements during emplacement of the feeder dike, and seismic and electrical studies.

  15. Recurrent patterns in fluid geochemistry data prior to phreatic eruptions

    NASA Astrophysics Data System (ADS)

    Rouwet, Dmitri; Sandri, Laura; Todesco, Micol; Tonini, Roberto; Pecoraino, Giovannella; Diliberto, Iole Serena

    2016-04-01

    Not all volcanic eruptions are magma-driven: the sudden evaporation and expansion of heated groundwater may cause phreatic eruptions, where the magma involvement is absent or negligible. Active crater lakes top some of the volcanoes prone to phreatic activity. This kind of eruption may occur suddenly, and without clear warning: on September 27, 2014 a phreatic eruption of Ontake, Japan, occurred without timely precursors, killing 57 tourists near the volcano summit. Phreatic eruptions can thus be as fatal as higher VEI events, due to the lack of recognised precursory signals, and because of their explosive and violent nature. In this study, we tackle the challenge of recognising precursors to phreatic eruptions, by analysing the records of two "phreatically" active volcanoes in Costa Rica, i.e. Poás and Turrialba, respectively with and without a crater lake. These volcanoes cover a wide range of time scales in eruptive behaviour, possibly culminating into magmatic activity, and have a long-term multi-parameter dataset mostly describing fluid geochemistry. Such dataset is suitable for being analysed by objective pattern recognition techniques, in search for recurrent schemes. The aim is to verify the existence and nature of potential precursory patterns, which will improve our understanding of phreatic events, and allow the assessment of the associated hazard at other volcanoes, such as Campi Flegrei or Vulcano, in Italy. Quantitative forecast of phreatic activity will be performed with BET_UNREST, a Bayesian Event Tree tool recently developed within the framework of FP7 EU VUELCO project. The study will combine the analysis of fluid geochemistry data with pattern recognition and phreatic eruption forecast on medium and short-term. The study will also provide interesting hints on the features that promote or hinder phreatic activity in volcanoes that host well-developed hydrothermal circulation.

  16. The Eruption Forecasting Information System (EFIS) database project

    NASA Astrophysics Data System (ADS)

    Ogburn, Sarah; Harpel, Chris; Pesicek, Jeremy; Wellik, Jay; Pallister, John; Wright, Heather

    2016-04-01

    The Eruption Forecasting Information System (EFIS) project is a new initiative of the U.S. Geological Survey-USAID Volcano Disaster Assistance Program (VDAP) with the goal of enhancing VDAP's ability to forecast the outcome of volcanic unrest. The EFIS project seeks to: (1) Move away from relying on the collective memory to probability estimation using databases (2) Create databases useful for pattern recognition and for answering common VDAP questions; e.g. how commonly does unrest lead to eruption? how commonly do phreatic eruptions portend magmatic eruptions and what is the range of antecedence times? (3) Create generic probabilistic event trees using global data for different volcano 'types' (4) Create background, volcano-specific, probabilistic event trees for frequently active or particularly hazardous volcanoes in advance of a crisis (5) Quantify and communicate uncertainty in probabilities A major component of the project is the global EFIS relational database, which contains multiple modules designed to aid in the construction of probabilistic event trees and to answer common questions that arise during volcanic crises. The primary module contains chronologies of volcanic unrest, including the timing of phreatic eruptions, column heights, eruptive products, etc. and will be initially populated using chronicles of eruptive activity from Alaskan volcanic eruptions in the GeoDIVA database (Cameron et al. 2013). This database module allows us to query across other global databases such as the WOVOdat database of monitoring data and the Smithsonian Institution's Global Volcanism Program (GVP) database of eruptive histories and volcano information. The EFIS database is in the early stages of development and population; thus, this contribution also serves as a request for feedback from the community.

  17. Explosive volcanism on Hecates Tholus, Mars - Investigation of eruption conditions

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, P. J.; Head, J. W., III; Wilson, L.

    1982-01-01

    From a reexamination of the medium and high-resolution Viking images of Amazonian and Hesperian age volcanic centers on Mars, it is believed that an excellent example of well-preserved explosive activity does indeed exist close to the summit of Hecates Tholus. A mantled region to the west of the summit caldera is seen as an example of a geologically very recent plinian air fall ash deposit. Morphological evidence is presented for describing this as explosively generated material, and numerical models of magma ascent and eruption in the Martian environment are used to estimate the physical characteristics (eruption cloud height, magma discharge rate, magma volatile content, duration of activity, and vent size) for this event. Attention is also given to the implication of this eruptive style for the composition of the erupted magma.

  18. Database for potential hazards from future volcanic eruptions in California

    USGS Publications Warehouse

    White, Melissa N.; Ramsey, David W.; Miller, C. Dan

    2011-01-01

    More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the past 10,000 yr. Past volcanic activity has ranged in scale and type from small rhyolitic and basaltic eruptions through large catastrophic rhyolitic eruptions. Sooner or later, volcanoes in California will erupt again, and they could have serious impacts on the health and safety of the State's citizens as well as on its economy. This report describes the nature and probable distribution of potentially hazardous volcanic phenomena and their threat to people and property. It includes hazard-zonation maps that show areas relatively likely to be affected by future eruptions in California. This digital release contains information from maps of potential hazards from future volcanic eruptions in the state of California, published as Plate 1 in U.S. Geological Survey Bulletin 1847. The main component of this digital release is a spatial database prepared using geographic information systems (GIS) applications. This release also contains links to files to view or print the map plate, main report text, and accompanying hazard tables from Bulletin 1847. It should be noted that much has been learned about the ages of eruptive events in the State of California since the publication of Bulletin 1847 in 1989. For the most up to date information on the status of California volcanoes, please refer to the U.S. Geological Survey Volcano Hazards Program website.

  19. Intrusion triggering of the 2010 Eyjafjallajökull explosive eruption.

    PubMed

    Sigmundsson, Freysteinn; Hreinsdóttir, Sigrún; Hooper, Andrew; Arnadóttir, Thóra; Pedersen, Rikke; Roberts, Matthew J; Oskarsson, Níels; Auriac, Amandine; Decriem, Judicael; Einarsson, Páll; Geirsson, Halldór; Hensch, Martin; Ofeigsson, Benedikt G; Sturkell, Erik; Sveinbjörnsson, Hjörleifur; Feigl, Kurt L

    2010-11-18

    Gradual inflation of magma chambers often precedes eruptions at highly active volcanoes. During such eruptions, rapid deflation occurs as magma flows out and pressure is reduced. Less is known about the deformation style at moderately active volcanoes, such as Eyjafjallajökull, Iceland, where an explosive summit eruption of trachyandesite beginning on 14 April 2010 caused exceptional disruption to air traffic, closing airspace over much of Europe for days. This eruption was preceded by an effusive flank eruption of basalt from 20 March to 12 April 2010. The 2010 eruptions are the culmination of 18 years of intermittent volcanic unrest. Here we show that deformation associated with the eruptions was unusual because it did not relate to pressure changes within a single magma chamber. Deformation was rapid before the first eruption (>5 mm per day after 4 March), but negligible during it. Lack of distinct co-eruptive deflation indicates that the net volume of magma drained from shallow depth during this eruption was small; rather, magma flowed from considerable depth. Before the eruption, a ∼0.05 km(3) magmatic intrusion grew over a period of three months, in a temporally and spatially complex manner, as revealed by GPS (Global Positioning System) geodetic measurements and interferometric analysis of satellite radar images. The second eruption occurred within the ice-capped caldera of the volcano, with explosivity amplified by magma-ice interaction. Gradual contraction of a source, distinct from the pre-eruptive inflation sources, is evident from geodetic data. Eyjafjallajökull's behaviour can be attributed to its off-rift setting with a 'cold' subsurface structure and limited magma at shallow depth, as may be typical for moderately active volcanoes. Clear signs of volcanic unrest signals over years to weeks may indicate reawakening of such volcanoes, whereas immediate short-term eruption precursors may be subtle and difficult to detect. PMID:21085177

  20. Reconstructing recent basaltic fissure eruptions in the Afar Depression, Ethiopia, using satellite imagery

    NASA Astrophysics Data System (ADS)

    Barnie, T. D.; Ferguson, D. J.; Oppenheimer, C.

    2009-12-01

    Since 2005, there have been numerous dike intrusions in the Manda-Hararo rift segment in central Afar, Ethiopia, as part of an on-going rifting event similar to that which occurred at Krafla, Iceland between 1975 and 1984. Two of the dikes have been associated with basaltic fissure eruptions, in August 2007 and in June 2009. A large fissure eruption also occurred in the Erta ‘Ale volcanic range in northern Afar in November 2008, which may be related to the activity further south. These eruptions took place in remote areas and lasted only a few days, making field observation almost impossible. We must therefore rely on the geomorphology and geochemistry of the erupted deposits, and syn-eruption satellite observations of thermally emitted radiance and gas emissions to reconstruct the evolution of these eruptions. Reconstruction of the eruptions is important for i) understanding the relationship between dike intrusion and fissure eruption dynamics ii) understanding the relationship between eruption dynamics and the resulting deposits, iii) interpreting the deposits of pre-historic eruptions from previous rifting events, and iv) estimating the hazard posed to the local population by further activity. In this study we use pre- and post-eruption high resolution ASTER and ALI images to map the morphology of the erupted material, and SEVIRI and MODIS time series of the eruptions to track evolution of the vent dynamics and lava flows. These datasets are augmented by oblique aerial and ground based photographic and FLIR surveys of the cooling lava flows and tephra. ASTER and ALI images are also used to map older erupted materials, which allow us to compare this rifting event with previous events to anticipate future activity.

  1. Aurorae and Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  2. Aurorae and Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  3. Solar Eruptive Events

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2012-01-01

    It s long been known that the Sun plays host to the most energetic explosions in the solar system. But key insights into the forms that energy takes have only recently become available. Solar flares have been phenomena of both academic and practical interest since their discovery in 1859. From the academic point of view, they are the nearest events for studying the explosive release of energy in astrophysical magnetized plasmas. From the practical point of view, they disrupt communication channels on Earth, from telegraph communications in 1859 to radio and television signals today. Flares also wreak havoc on the electrical power grid, satellite operations, and GPS signals, and energetic charged particles and radiation are dangerous to passengers on high-altitude polar flights and to astronauts. Flares are not the only explosive phenomena on the Sun. More difficult to observe but equally energetic are the large coronal mass ejections (CMEs), the ejection of up to ten billion tons of magnetized plasma into the solar wind at speeds that can exceed 1000 km/s. CMEs are primarily observed from the side, with coronagraphs that block out the bright disk of the Sun and lower solar atmosphere so that light scattered from the ejected mass can be seen. Major geomagnetic storms are now known to arise from the interaction of CMEs with Earth's magnetosphere. Solar flares are observed without CMEs, and CMEs are observed without flares. The two phenomena often occur together, however, and almost always do in the case of large flares and fast CMEs. The term solar eruptive event refers to the combination of a flare and a CME. Solar eruptive events generate a lot of heat: They can heat plasma to temperatures as high at 50 million Kelvin, producing radiation across the electromagnetic spectrum. But that s not all. A fascinating aspect of solar eruptive events is the acceleration of electrons and ions to suprathermal often relativistic energies. The accelerated particles are primarily

  4. Eruption-induced modifications to volcanic seismicity at Ruapehu, New Zealand, and its implications for eruption forecasting

    USGS Publications Warehouse

    Bryan, C.J.; Sherburn, S.

    2003-01-01

    Broadband seismic data collected on Ruapehu volcano, New Zealand, in 1994 and 1998 show that the 1995-1996 eruptions of Ruapehu resulted in a significant change in the frequency content of tremor and volcanic earthquakes at the volcano. The pre-eruption volcanic seismicity was characterized by several independent dominant frequencies, with a 2 Hz spectral peak dominating the strongest tremor and volcanic earthquakes and higher frequencies forming the background signal. The post-eruption volcanic seismicity was dominated by a 0.8-1.4 Hz spectral peak not seen before the eruptions. The 2 Hz and higher frequency signals remained, but were subordinate to the 0.8-1.4 Hz energy. That the dominant frequencies of volcanic tremor and volcanic earthquakes were identical during the individual time periods prior to and following the 1995-1996 eruptions suggests that during each of these time periods the volcanic tremor and earthquakes were generated by the same source process. The overall change in the frequency content, which occurred during the 1995-1996 eruptions and remains as of the time of the writing of this paper, most likely resulted from changes in the volcanic plumbing system and has significant implications for forecasting and real-time assessment of future eruptive activity at Ruapehu.

  5. Failed eruptions of two intertwining small-scale filaments

    NASA Astrophysics Data System (ADS)

    Xue, Zhike; Yan, Xiaoli; Zhao, Li; Xiang, Yongyuan; Yang, Liheng; Guo, Yang

    2016-02-01

    Using multi-wavelength observations of the New Vacuum Solar Telescope (NVST), the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO), we study the topology and evolutions of two filaments observed in NOAA active region (AR) 12031 on 2014 April 7. Before their eruptions, the two filaments (F1 and F2) were sinistral filaments, and the left part of F1 (LP) was located above F2, the right part of F1 (RP) under F2. They show an overall intertwining structure. LP erupted first and rotated clockwise. The total rotation angle was about 470° (≈2.61π). With its rotation, most of the plasma fell back, and thus it was a failed eruption. Meanwhile, when LP erupted to a higher altitude, the overlying magnetic loops were partially pushed from the northeast to the southwest with projected speeds from 36 to 105 km s-1. Next, F2 began to erupt and, when reaching a certain height, the plasma of F2 started to fall down to their footpoints. Using the potential-field source-surface (PFSS) model, the decay indexes at five positions along the polarity inversion line of AR 12031 were calculated to be from 1.03 to 1.25 with an average value of 1.20 that was lower than the critical value for torus instability. These results imply that the kink instability was the main triggering mechanism for the eruption of F1, and the eruption of F2 was due to the decreasing of overlying magnetic loops caused by the eruption of F1. The eruptions of two filaments were confined by the large-scale overlying magnetic loops.

  6. Shallow lateral magma migration or not during the Bárðarbunga 2014 activity and preceding the Flæðahraun eruption: the geochemical perspective.

    NASA Astrophysics Data System (ADS)

    Sigmarsson, Olgeir

    2015-04-01

    Basaltic fissure eruptions several tens of km away from central volcanoes in Iceland are interpreted to reflect either lateral magma migration from a shallow magma chamber beneath the central volcano, or vertical dyke propagation from deep magma reservoir underlying large part of the fissure swarm. During the Krafla Fires (1975-1984) basalts emitted within the caldera of the central volcano and far away out on the fissure swarm have different composition. During the subglacial eruption at Gjálp (1996), halfway between Grímsvötn and Bárdarbunga, the erupted magma had identical isotope ratios as that of the former but different from that of the latter, despite earthquake originating at Bárdarbunga and propagation towards the eruption site at Gjálp. These geochemical fingerprints have been taken to indicate that lateral magma migration over tens of km was an unlikely process. The spectacular lateral migration of seismicity from 16 August to 29 August and associated ground deformation has been interpreted to reflect a lateral dyke injection over 45 km, from a shallow magma chamber beneath the Bárðarbunga central volcano to the eruption site forming the new Flæðahraun (Sigmundsson et al., 2015). The isotope ratio of Sr in Flæðahraun is identical to that of Holocene lavas and tephra produced at the Bárdarbunga Volcanic System confirming uniform Sr isotope ratios at a given volcanic system in Iceland. Thermodynamic equlibrium between mineral and magmatic liquid indicate that the first Flæðahraun olivine tholeiite originated from more than 10 km depth at a temperature of approximately 1180 °C. Basalt this hot is not likely to have been stored in a superficial magma chamber before migrating laterally at shallow depth over 40 km beneath a glacier covered surface. Basalts crystallizing at variable depth should have different trace element composition caused by evolving crystallizing mineral assemblage, where plagioclase proportions should increase with

  7. Large and small volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust; Mohajeri, Nahid

    2013-04-01

    Despite great progress in volcanology in the past decades, we still cannot make reliable forecasts as to the likely size (volume, mass) of an eruption once it has started. Empirical data collected from volcanoes worldwide indicates that the volumes (or masses) of eruptive materials in volcanic eruptions are heavy-tailed. This means that most of the volumes erupted from a given magma chamber are comparatively small. Yet, the same magma chamber can, under certain conditions, squeeze out large volumes of magma. To know these conditions is of fundamental importance for forecasting the likely size of an eruption. Thermodynamics provides the basis for understanding the elastic energy available to (i) propagate an injected dyke from the chamber and to the surface to feed an eruption, and (ii) squeeze magma out of the chamber during the eruption. The elastic energy consists of two main parts: first, the strain energy stored in the volcano before magma-chamber rupture and dyke injection, and, second, the work done through displacement of the flanks of the volcano (or the margins of a rift zone) and the expansion and shrinkage of the magma chamber itself. Other forms of energy in volcanoes - thermal, seismic, kinetic - are generally important but less so for squeezing magma out of a chamber during an eruption. Here we suggest that for (basaltic) eruptions in rift zones the strain energy is partly related to minor doming above the reservoir, and partly to stretching of the rift zone before rupture. The larger the reservoir, the larger is the stored strain energy before eruption. However, for the eruption to be really large, the strain energy has to accumulate in the entire crustal segment above the reservoir and there will be additional energy input into the system during the eruption which relates to the displacements of the boundary of the rift-zone segment. This is presumably why feeder dykes commonly propagate laterally at the surface following the initial fissure

  8. Investigation of Solar Eruptive Prominences

    NASA Astrophysics Data System (ADS)

    Su, Yingna; McCauley, Patrick; van Ballegooijen, Adriaan; Ji, Haisheng; Reeves, Katharine; DeLuca, Edward

    2015-08-01

    At first, we will present an investigation of the polar crown prominence that erupted on 2012 March 12. This prominence is observed at the southeast limb by SDO/AIA (end-on view) and displays a quasi vertical-thread structure. Bright U-shape (horn-like) structure is observed surrounding the upper portion of the prominence (171 Angstrom) before the eruption and becomes more prominent during the eruption. When viewed on the disk, STEREO-B shows that this long prominence is composed of a series of vertical threads and displays a half loop-like structure during the eruption. We focus on the magnetic support of the prominence by studying the structure and dynamics of the prominence before and during the eruption using observations from SDO and STEREO. We construct a series of magnetic field models (including sheared arcade model, twisted flux rope model, and model with HFT), then compare with observations. Various observational characteristics appear to support the twisted flux rope model. Our study suggests that the flux rope supporting the prominence enters the regime of torus instability at the onset of the fast rise phase, and signature of reconnection appears about one hour later. In the second part, we will present a statistical study on the kinematics of limb eruptive prominences observed by SDO/AIA. A brief introduction on an online catalog of prominence eruptions observed by SDO/AIA will also be presented.

  9. SYMPATHETIC FILAMENT ERUPTIONS FROM A BIPOLAR HELMET STREAMER IN THE SUN

    SciTech Connect

    Yang Jiayan; Jiang Yunchun; Zheng Ruisheng; Bi Yi; Hong Junchao; Yang Bo

    2012-01-20

    On 2005 August 5, two solar filaments erupted successively from different confined arcades underlying a common overarching multiple-arcade bipolar helmet streamer. We present detailed observations of these two events and identify them as sympathetic filament eruptions. The first (F1) is a small active-region filament located near the outskirts of the streamer arcade. It underwent a nonradial eruption, initially moving in the interior of the streamer arcade and resulting in an over-and-out coronal mass ejection. The second filament (F2), a larger quiescent one far away from F1, was clearly disturbed during the F1 eruption. It then underwent a very slow eruption and finally disappeared completely and permanently. Because two belt-shaped diffuse dimmings formed along the footprints of the streamer arcade in the first eruption and persisted throughout the complete disappearance of F2, the eruption series are interpreted as sympathetic: the simple expansion of the common streamer arcade forced by the F1 eruption weakened magnetic flux overlying F2 and thus led to its slow eruption, with the dimming formation indicating their physical connection. Our observations suggest that multiple-arcade bipolar helmet-streamer configurations are appropriate to producing sympathetic eruptions. Combined with the recent observations of unipolar-streamer sympathetic events, it appears that a multiple-arcade unipolar or bipolar helmet streamer can serve as a common magnetic configuration for sympathetic eruptions.

  10. An Analysis of Eruptions Detected by the LMSAL Eruption Patrol

    NASA Astrophysics Data System (ADS)

    Hurlburt, N. E.; Higgins, P. A.; Jaffey, S.

    2014-12-01

    Observations of the solar atmosphere reveals a wide range of real and apparent motions, from small scale jets and spicules to global-scale coronal mass ejections. Identifying and characterizing these motions are essential to advance our understanding the drivers of space weather. Automated and visual identifications are used in identifying CMEs. To date, the precursors to these — eruptions near the solar surface — have been identified primarily by visual inspection. Here we report on an analysis of the eruptions detected by the Eruption Patrol, a data mining module designed to automatically identify eruptions from data collected by Solar Dynamics Observatory's Atmospheric Imaging Assembly (SDO/AIA). We describe the module and use it both to explore relations with other solar events recorded in the Heliophysics Event Knowledgebase and to identify and access data collected by the Interface Region Imaging Spectrograph (IRIS) and Solar Optical Telescope (SOT) on Hinode for further analysis.

  11. Characterization of Solar Eruptions reported by EruptionPatrol

    NASA Astrophysics Data System (ADS)

    Hurlburt, Neal

    2015-04-01

    Observation of the solar atmosphere reveals a wide range of real and apparent motions, from small scale jets and spicules to global-scale coronal mass ejections. Identifying and characterizing these motions are essential to advance our understanding the drivers of space weather. A method for automatically identifying eruptions near the solar surface (either from filaments or otherwise) has recently been developed and integrated into the Heliophysics Events Knowledgebase. Here we report on the EruptionPatrol module for identifying eruptions in data collected by the SDO/AIA instrument and on the characterization and analysis of its output. A cluster analysis on the time periods reported by EruptionPatrol demarcates several large-scale events spanning significant portions of the solar disk with lifetimes of up to six hours.

  12. Spectacular lightning revealed in 2009 Mount Redoubt eruption

    NASA Astrophysics Data System (ADS)

    Behnke, Sonja A.; Thomas, Ronald J.; Krehbiel, Paul R.; McNutt, Stephen R.

    2012-05-01

    The explosive eruption of Alaska's Mount Redoubt volcano in March and April 2009 provided a superb opportunity for studying volcanic lightning. The energetic explosions produced powerful volcanic lightning storms, the largest of which rivaled the intensity of the massive supercell thunderstorms that frequent the midwestern Great Plains. Although lightning often has been observed in the plumes of explosive volcanic eruptions, only a handful of detailed studies have delved into the origins of volcanic lightning. Active volcanoes tend to be situated in remote locations, where they are difficult to observe, and often have sudden, unpredicted eruptions. Even when the eruptions are observed close at hand, the volcanic clouds are intensely opaque, obscuring most of the lightning from view.

  13. A new paradigm for solar filament eruptions

    NASA Astrophysics Data System (ADS)

    Rust, David M.

    2001-11-01

    This article discusses the formation, magnetic structure, and eruption of solar filaments in terms of two contrasting paradigms. The standard paradigm is that filaments are formed by condensation of plasma on coronal magnetic fields that are twisted or dimpled as a result of photospheric motions. According to this paradigm, filaments erupt when photospheric motions shear the fields, increasing their energy and decreasing their stability. According to a new paradigm, subsurface motions generate toroidal magnetic flux ropes, and after these flux ropes emerge to form active regions, the most twisted parts migrate into the corona to form filaments. Filaments become unstable and are ejected after a sufficient accumulation of twist (i.e., magnetic helicity). Various proposed mechanisms for producing the needed helicity are reviewed, and several observational tests are proposed to differentiate among the possible mechanisms.

  14. Learning to recognize volcanic non-eruptions

    USGS Publications Warehouse

    Poland, Michael P.

    2010-01-01

    An important goal of volcanology is to answer the questions of when, where, and how a volcano will erupt—in other words, eruption prediction. Generally, eruption predictions are based on insights from monitoring data combined with the history of the volcano. An outstanding example is the A.D. 1980–1986 lava dome growth at Mount St. Helens, Washington (United States). Recognition of a consistent pattern of precursors revealed by geophysical, geological, and geochemical monitoring enabled successful predictions of more than 12 dome-building episodes (Swanson et al., 1983). At volcanic systems that are more complex or poorly understood, probabilistic forecasts can be useful (e.g., Newhall and Hoblitt, 2002; Marzocchi and Woo, 2009). In such cases, the probabilities of different types of volcanic events are quantified, using historical accounts and geological studies of a volcano's past activity, supplemented by information from similar volcanoes elsewhere, combined with contemporary monitoring information.

  15. Comparing Dynamics in Eruptive and Non-Eruptive Flares

    NASA Astrophysics Data System (ADS)

    Nitta, Nariaki; Tarbell, Theodore D.; Slater, Gregory L.; Frank, Zoe Anne

    2016-05-01

    Close comparison of EUV and coronagraph data suggests that there may not be clear distinction between eruptive and non-eruptive flares as far as the coronal and chromospheric signatures are concerned. Here we define eruptive and non-eruptive flares in terms of the presence and absence of the associated coronal mass ejection (CME). We have studied several flares in both categories using Hinode/SOT and IRIS data. The pointing of the Hinode/SOT data has been updated by correlating them with AIA 1700 A images. We show our initial results about how the flare development compares in eruptive and non-eruptive flares, including the reconnection rate as derived from the magnetic field swept over by flare ribbons (in SOT Ca images), and the line-of-sight velocities at different locations and temperatures (in IRIS spectral data). We also discuss large-scale disturbances and related CMEs in SDO/AIA and SOHO/LASCO data as context information.

  16. Hydroacoustic, infrasonic and seismic monitoring of the submarine eruptive activity and sub-aerial plume generation at South Sarigan, May 2010

    NASA Astrophysics Data System (ADS)

    Green, David N.; Evers, Läslo G.; Fee, David; Matoza, Robin S.; Snellen, Mirjam; Smets, Pieter; Simons, Dick

    2013-05-01

    Explosive submarine volcanic processes are poorly understood, due to the difficulties associated with both direct observation and continuous monitoring. In this study hydroacoustic, infrasound, and seismic signals recorded during the May 2010 submarine eruption of South Sarigan seamount, Marianas Arc, are used to construct a detailed event chronology. The signals were recorded on stations of the International Monitoring System, which is a component of the verification measures for the Comprehensive Nuclear-Test-Ban Treaty. Numerical hydroacoustic and infrasound propagation modelling confirms that viable propagation paths from the source to receivers exist, and provide traveltimes allowing signals recorded on the different technologies to be associated. The eruption occurred in three stages, separated by three-hour periods of quiescence. 1) A 46 h period during which broadband impulsive hydroacoustic signals were generated in clusters lasting between 2 and 13 min. 95% of the 7602 identified events could be classified into 4 groups based on their waveform similarity. The time interval between clusters decreased steadily from 80 to 25 min during this period. 2) A five-hour period of 10 Hz hydroacoustic tremor, interspersed with large-amplitude, broadband signals. Associated infrasound signals were also recorded at this time. 3) An hour-long period of transient broadband events culminated in two large-amplitude hydroacoustic events and one broadband infrasound signal. A speculative interpretation, consistent with the data, suggests that during phase (1) transitions between endogenous dome growth and phreatomagmatic explosions occurred with the magma ascent rate accelerating throughout the period; during phase (2) continuous venting of fragmented magma occurred, and was powerful enough to breach the sea surface. During the climactic phase (3) discrete powerful explosions occurred, and sufficient seawater was vaporised to produce the contemporaneous 12 km altitude steam

  17. Petrology of the 2004-2006 Mount St. Helens lava dome -- implications for magmatic plumbing and eruption triggering: Chapter 30 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Pallister, John S.; Thornber, Carl R.; Cashman, Katharine V.; Clynne, Michael A.; Lowers, Heather; Mandeville, Charles W.; Brownfield, Isabelle K.; Meeker, Gregory P.

    2008-01-01

    The question of new versus residual magma has implications for the long-term eruptive behavior of Mount St. Helens, because arrival of a new batch of dacitic magma from the deep crust could herald the beginning of a new long-term cycle of eruptive activity. It is also important to our understanding of what triggered the eruption and its future course. Two hypotheses for triggering are considered: (1) top-down fracturing related to the shallow groundwater system and (2) an increase in reservoir pressure brought about by recent magmatic replenishment. With respect to the future course of the eruption, similarities between textures and character of eruption of the 2004-6 dome and the long-duration (greater than 100 years) pre-1980 summit dome, along with the low eruptive rate of the current eruption, suggest that the eruption could continue sluggishly or intermittently for years to come.

  18. Eruption Forecasting: Success and Surprise at Kasatochi and Okmok Volcanoes

    NASA Astrophysics Data System (ADS)

    Prejean, S.; Power, J.; Brodsky, E.

    2008-12-01

    In the summer of 2008, the Alaska Volcano Observatory (AVO) successfully forecast eruption at an unmonitored volcano, Kasatochi, and was unable to forecast eruption at a well monitored volcano, Okmok. We use these case studies to explore the limitations and opportunities of seismically monitored and unmonitored systems and to evaluate situations when we can expect to succeed and when we must expect to fail in eruption forecasting. Challenges in forecasting eruptions include interpreting seismicity in context of volcanic history, developing a firm understanding of distance scales over which pre- and co-eruptive seismic signals are observed, and improving our ability to discriminate processes causing tremor. Kasatochi Volcano is a 3 km wide island in the central Aleutian Islands with no confirmed historical activity. Little is known about the eruptive history of the volcano. It was not considered an immediate threat until 3 days prior to eruption. A report of ground shaking by a biology field crew on the island on August 4 was the first indication of unrest. On August 6 a vigorous seismic swarm became apparent on the nearest seismic stations 40 km distant. The aviation color code/volcano alert level at Kasatochi was increased to Yellow/Advisory in response to increasing magnitude and frequency of earthquakes. The color code/alert level was increased to Orange/Watch on August 7 when volcanic tremor was observed in the wake of the largest earthquake in the sequence, a M 5.6. Three hours after the onset of volcanic tremor, eruption was confirmed by satellite data and the color code/alert level increased to Red/Warning. Eruption forecasting was possible only due to the exceptionally large moment release of pre-eruptive seismicity. The key challenge in evaluating the situation was distinguishing between tectonic activity and a volcanic swarm. It is likely there were weeks to months of precursory seismicity, however little instrumental record exists due to the lack of a

  19. Tenofovir induced lichenoid drug eruption

    PubMed Central

    Gupta, Mrinal; Gupta, Heena; Gupta, Anish

    2015-01-01

    Cutaneous adverse reactions are a common complication of anti-retroviral therapy. Tenofovir is a newer anti-retroviral drug belonging to the nucleotide reverse transcriptase inhibitor group. Systemic adverse effects like nausea, vomiting, diarrhea, hepatotoxicity and renal toxicity are common with tenofovir but cutaneous adverse effects are rare. Lichenoid drug eruptions are a common adverse effect seen with a large variety of drugs including antimalarials, antihypertensives, nonsteroidal anti-inflammatory drugs and diuretics. Lichenoid drug eruption is a rare cutaneous adverse effect of tenofovir with only a single case reported till date. Here, we report a case of tenofovir induced lichenoid drug eruption in a 54-year-old human immunodeficiency virus affected male who presented with generalized lichenoid eruption after 6 weeks of initiation of tenofovir and complete clearance on cessation of the drug. PMID:26229762

  20. Voyager 2 Jupiter Eruption Movie

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This movie records an eruptive event in the southern hemisphere of Jupiter over a period of 8 Jupiter days. Prior to the event, an undistinguished oval cloud mass cruised through the turbulent atmosphere. The eruption occurs over avery short time at the very center of the cloud. The white eruptive material is swirled about by the internal wind patterns of the cloud. As a result of the eruption, the cloud then becomes a type of feature seen elsewhere on Jupiter known as 'spaghetti bowls'.

    As Voyager 2 approached Jupiter in 1979, it took images of the planet at regular intervals. This sequence is made from 8 images taken once every Jupiter rotation period (about 10 hours). These images were acquired in the Violet filter around May 6, 1979. The spacecraft was about 50 million kilometers from Jupiter at that time.

    This time-lapse movie was produced at JPL by the Image Processing Laboratory in 1979.

  1. Scoria cone formation through a violent Strombolian eruption: Irao Volcano, SW Japan

    NASA Astrophysics Data System (ADS)

    Kiyosugi, Koji; Horikawa, Yoshiyuki; Nagao, Takashi; Itaya, Tetsumaru; Connor, Charles B.; Tanaka, Kazuhiro

    2014-01-01

    Scoria cones are common volcanic features and are thought to most commonly develop through the deposition of ballistics produced by gentle Strombolian eruptions and the outward sliding of talus. However, some historic scoria cones have been observed to form with phases of more energetic violent Strombolian eruptions (e.g., the 1943-1952 eruption of Parícutin, central Mexico; the 1975 eruption of Tolbachik, Kamchatka), maintaining volcanic plumes several kilometers in height, sometimes simultaneous with active effusive lava flows. Geologic evidence shows that violent Strombolian eruptions during cone formation may be more common than is generally perceived, and therefore it is important to obtain additional insights about such eruptions to better assess volcanic hazards. We studied Irao Volcano, the largest basaltic monogenetic volcano in the Abu Monogenetic Volcano Group, SW Japan. The geologic features of this volcano are consistent with a violent Strombolian eruption, including voluminous ash and fine lapilli beds (on order of 10-1 km3 DRE) with simultaneous scoria cone formation and lava effusion from the base of the cone. The characteristics of the volcanic products suggest that the rate of magma ascent decreased gradually throughout the eruption and that less explosive Strombolian eruptions increased in frequency during the later stages of activity. During the eruption sequence, the chemical composition of the magma became more differentiated. A new K-Ar age determination for phlogopite crystallized within basalt dates the formation of Irao Volcano at 0.4 ± 0.05 Ma.

  2. Forecasting the duration of volcanic eruptions: an empirical probabilistic model

    NASA Astrophysics Data System (ADS)

    Gunn, L. S.; Blake, S.; Jones, M. C.; Rymer, H.

    2014-01-01

    The ability to forecast future volcanic eruption durations would greatly benefit emergency response planning prior to and during a volcanic crises. This paper introduces a probabilistic model to forecast the duration of future and on-going eruptions. The model fits theoretical distributions to observed duration data and relies on past eruptions being a good indicator of future activity. A dataset of historical Mt. Etna flank eruptions is presented and used to demonstrate the model. The data have been compiled through critical examination of existing literature along with careful consideration of uncertainties on reported eruption start and end dates between the years 1300 AD and 2010. Data following 1600 is considered to be reliable and free of reporting biases. The distribution of eruption duration between the years 1600 and 1669 is found to be statistically different from that following it and the forecasting model is run on two datasets of Mt. Etna flank eruption durations: 1600-2010 and 1670-2010. Each dataset is modelled using a log-logistic distribution with parameter values found by maximum likelihood estimation. Survivor function statistics are applied to the model distributions to forecast (a) the probability of an eruption exceeding a given duration, (b) the probability of an eruption that has already lasted a particular number of days exceeding a given total duration and (c) the duration with a given probability of being exceeded. Results show that excluding the 1600-1670 data has little effect on the forecasting model result, especially where short durations are involved. By assigning the terms `likely' and `unlikely' to probabilities of 66 % or more and 33 % or less, respectively, the forecasting model based on the 1600-2010 dataset indicates that a future flank eruption on Mt. Etna would be likely to exceed 20 days (± 7 days) but unlikely to exceed 86 days (± 29 days). This approach can easily be adapted for use on other highly active, well

  3. Eruption probabilities for the Lassen Volcanic Center and regional volcanism, northern California, and probabilities for large explosive eruptions in the Cascade Range

    USGS Publications Warehouse

    Nathenson, Manuel; Clynne, Michael A.; Muffler, L.J. Patrick

    2012-01-01

    Chronologies for eruptive activity of the Lassen Volcanic Center and for eruptions from the regional mafic vents in the surrounding area of the Lassen segment of the Cascade Range are here used to estimate probabilities of future eruptions. For the regional mafic volcanism, the ages of many vents are known only within broad ranges, and two models are developed that should bracket the actual eruptive ages. These chronologies are used with exponential, Weibull, and mixed-exponential probability distributions to match the data for time intervals between eruptions. For the Lassen Volcanic Center, the probability of an eruption in the next year is 1.4x10-4 for the exponential distribution and 2.3x10-4 for the mixed exponential distribution. For the regional mafic vents, the exponential distribution gives a probability of an eruption in the next year of 6.5x10-4, but the mixed exponential distribution indicates that the current probability, 12,000 years after the last event, could be significantly lower. For the exponential distribution, the highest probability is for an eruption from a regional mafic vent. Data on areas and volumes of lava flows and domes of the Lassen Volcanic Center and of eruptions from the regional mafic vents provide constraints on the probable sizes of future eruptions. Probabilities of lava-flow coverage are similar for the Lassen Volcanic Center and for regional mafic vents, whereas the probable eruptive volumes for the mafic vents are generally smaller. Data have been compiled for large explosive eruptions (>≈ 5 km3 in deposit volume) in the Cascade Range during the past 1.2 m.y. in order to estimate probabilities of eruption. For erupted volumes >≈5 km3, the rate of occurrence since 13.6 ka is much higher than for the entire period, and we use these data to calculate the annual probability of a large eruption at 4.6x10-4. For erupted volumes ≥10 km3, the rate of occurrence has been reasonably constant from 630 ka to the present, giving

  4. Infrasound research of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Marchetti, Emanuele; Ripepe, Maurizio

    2016-04-01

    Volcanic eruptions are efficient sources of infrasound produced by the rapid perturbation of the atmosphere by the explosive source. Being able to propagate up to large distances from the source, infrasonic waves from major (VEI 4 or larger) volcanic eruptions have been recorded for many decades with analogue micro-barometers at large regional distances. In late 1980s, near-field observations became progressively more common and started to have direct impact on the understanding and modeling of explosive source dynamics, to eventually play a primary role in volcano research. Nowadays, infrasound observation from a large variety of volcanic eruptions, spanning from VEI 0 to VEI 5 events, has shown a dramatic variability in terms of signature, excess pressure and frequency content of radiated infrasound and has been used to infer complex eruptive source mechanisms for the different kinds of events. Improved processing capability and sensors has allowed unprecedented precise locations of the explosive source and is progressively increasing the possibility to monitor volcanoes from distant records. Very broadband infrasound observations is also showing the relation between volcanic eruptions and the atmosphere, with the eruptive mass injection in the atmosphere triggering acoustic-gravity waves which eventually might control the ash dispersal and fallout.

  5. A novel approach to estimate the eruptive potential and probability in open conduit volcanoes

    NASA Astrophysics Data System (ADS)

    de Gregorio, Sofia; Camarda, Marco

    2016-07-01

    In open conduit volcanoes, volatile-rich magma continuously enters into the feeding system nevertheless the eruptive activity occurs intermittently. From a practical perspective, the continuous steady input of magma in the feeding system is not able to produce eruptive events alone, but rather surplus of magma inputs are required to trigger the eruptive activity. The greater the amount of surplus of magma within the feeding system, the higher is the eruptive probability.Despite this observation, eruptive potential evaluations are commonly based on the regular magma supply, and in eruptive probability evaluations, generally any magma input has the same weight. Conversely, herein we present a novel approach based on the quantification of surplus of magma progressively intruded in the feeding system. To quantify the surplus of magma, we suggest to process temporal series of measurable parameters linked to the magma supply. We successfully performed a practical application on Mt Etna using the soil CO2 flux recorded over ten years.

  6. A novel approach to estimate the eruptive potential and probability in open conduit volcanoes

    PubMed Central

    De Gregorio, Sofia; Camarda, Marco

    2016-01-01

    In open conduit volcanoes, volatile-rich magma continuously enters into the feeding system nevertheless the eruptive activity occurs intermittently. From a practical perspective, the continuous steady input of magma in the feeding system is not able to produce eruptive events alone, but rather surplus of magma inputs are required to trigger the eruptive activity. The greater the amount of surplus of magma within the feeding system, the higher is the eruptive probability.Despite this observation, eruptive potential evaluations are commonly based on the regular magma supply, and in eruptive probability evaluations, generally any magma input has the same weight. Conversely, herein we present a novel approach based on the quantification of surplus of magma progressively intruded in the feeding system. To quantify the surplus of magma, we suggest to process temporal series of measurable parameters linked to the magma supply. We successfully performed a practical application on Mt Etna using the soil CO2 flux recorded over ten years. PMID:27456812

  7. A novel approach to estimate the eruptive potential and probability in open conduit volcanoes.

    PubMed

    De Gregorio, Sofia; Camarda, Marco

    2016-01-01

    In open conduit volcanoes, volatile-rich magma continuously enters into the feeding system nevertheless the eruptive activity occurs intermittently. From a practical perspective, the continuous steady input of magma in the feeding system is not able to produce eruptive events alone, but rather surplus of magma inputs are required to trigger the eruptive activity. The greater the amount of surplus of magma within the feeding system, the higher is the eruptive probability.Despite this observation, eruptive potential evaluations are commonly based on the regular magma supply, and in eruptive probability evaluations, generally any magma input has the same weight. Conversely, herein we present a novel approach based on the quantification of surplus of magma progressively intruded in the feeding system. To quantify the surplus of magma, we suggest to process temporal series of measurable parameters linked to the magma supply. We successfully performed a practical application on Mt Etna using the soil CO2 flux recorded over ten years. PMID:27456812

  8. Explosion Quakes: The 2007 Eruption of Pavlof

    NASA Astrophysics Data System (ADS)

    Smith, C.; McNutt, S. R.; Thompson, G.

    2014-12-01

    Pavlof Volcano on the Alaska Peninsula began to erupt on August 14, 2007 after an 11 year repose. Pavlof is the most active volcano in the Aleutians, with over 40 eruptions in historical times. The 2007 eruption began with low-frequency earthquakes and thermal anomalies. Strombolian activity occurred from a newly formed vent on the SE flank of the volcano. The plume reached 20,000 ft during the peak of the eruption on August 29th and 30th. Seismic activity, monitored by a network of 5 local instruments, consisted of low-frequency events, explosion quakes, volcanic tremor, and lahar-generated signals. Here we focus on explosion quakes. The first explosion quake occurred August 14th at 2:54pm UTC and the last on September 13th at 3:14pm UTC. Explosion events were often embedded in continuous tremor, but could be distinguished by the ground-coupled air waves, which appeared as a high-frequency spike superimposed on the lower-frequency ground waves. Rates were as high as 19 explosion quakes per minute. We establish whether systematic changes in explosion rates, signal properties, and ground-coupled air-wave amplitudes correlate with the height and ash content of the plume. First order trends show a positive correlation between increased explosion quake rates, increased amplitudes, and plume height. In addition, we investigate how atmospheric conditions such as wind speed and direction affect the recording of the ground-coupled air-wave. The time differences in the airwaves at different stations are consistent with the acoustic speed of 340 m/s, but show variations of up to 0.6 s depending on wind speed and direction. Eruptions at Pavlof typically have little or no seismic precursors; this combined with the low visibility common to the area results in Pavlof being dangerous to the many aviation routes that transverse this airspace. It is the goal of this study to determine the conditions under which explosion quake data may be reliably used for more effective monitoring.

  9. Pre- and syn-eruptive degassing and crystallisation processes of the 2010 and 2006 eruptions of Merapi volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Preece, Katie; Gertisser, Ralf; Barclay, Jenni; Berlo, Kim; Herd, Richard A.

    2014-10-01

    The 2010 eruption of Merapi (VEI 4) was the volcano's largest since 1872. In contrast to the prolonged and effusive dome-forming eruptions typical of Merapi's recent activity, the 2010 eruption began explosively, before a new dome was rapidly emplaced. This new dome was subsequently destroyed by explosions, generating pyroclastic density currents (PDCs), predominantly consisting of dark coloured, dense blocks of basaltic andesite dome lava. A shift towards open-vent conditions in the later stages of the eruption culminated in multiple explosions and the generation of PDCs with conspicuous grey scoria and white pumice clasts resulting from sub-plinian convective column collapse. This paper presents geochemical data for melt inclusions and their clinopyroxene hosts extracted from dense dome lava, grey scoria and white pumice generated during the peak of the 2010 eruption. These are compared with clinopyroxene-hosted melt inclusions from scoriaceous dome fragments from the prolonged dome-forming 2006 eruption, to elucidate any relationship between pre-eruptive degassing and crystallisation processes and eruptive style. Secondary ion mass spectrometry analysis of volatiles (H2O, CO2) and light lithophile elements (Li, B, Be) is augmented by electron microprobe analysis of major elements and volatiles (Cl, S, F) in melt inclusions and groundmass glass. Geobarometric analysis shows that the clinopyroxene phenocrysts crystallised at depths of up to 20 km, with the greatest calculated depths associated with phenocrysts from the white pumice. Based on their volatile contents, melt inclusions have re-equilibrated during shallower storage and/or ascent, at depths of ~0.6-9.7 km, where the Merapi magma system is interpreted to be highly interconnected and not formed of discrete magma reservoirs. Melt inclusions enriched in Li show uniform "buffered" Cl concentrations, indicating the presence of an exsolved brine phase. Boron-enriched inclusions also support the presence of a

  10. A phenomenological model for precursor volcanic eruptions.

    PubMed

    Menand, T; Tait, S R

    2001-06-01

    Intense explosions of relatively short duration frequently precede large explosive and effusive volcanic eruptions-by as much as weeks to months in the case of very viscous magmas. In some cases, such pre-eruption activity has served as a sufficient warning to those living in the vicinity to evacuate and avoid calamity. Precursor events seem to be related to the formation of a magma pathway to the surface, but their precise interpretation is a long-standing puzzle. It has been inferred from theoretical studies that exsolution of volatiles might create an almost separate gas pocket at the tip of a propagating dyke. Here we explain the role that such a process may have, using a laboratory study of the transient propagation of a liquid-filled crack with a gas pocket at its tip that grows with time. We show that once the gas pocket acquires sufficient buoyancy to overcome the fracture resistance of the host solid the dynamics of the gas pocket, rather than those of the liquid, determine the velocity of the crack tip. Furthermore, we find that the gas can ultimately separate from the liquid. We propose that fast-moving, gas-rich pockets reaching the surface ahead of the main liquid-filled fissure could be the origin of many precursor eruptions. PMID:11395766

  11. Victims from volcanic eruptions: a revised database

    NASA Astrophysics Data System (ADS)

    Tanguy, J.-C.; Ribière, C.; Scarth, A.; Tjetjep, W. S.

    The number of victims from volcanism and the primary cause(s) of death reported in the literature show considerable uncertainty. We present the results of investigations carried out either in contemporary accounts or in specific studies of eruptions that occurred since A.D. 1783. More than 220 000 people died because of volcanic activity during this period, which includes approximately 90% of the recorded deaths throughout history. Most of the fatalities resulted from post-eruption famine and epidemic disease (30.3%), nuées ardentes or pyroclastic flows and surges (26.8%), mudflows or lahars (17.1%), and volcanogenic tsunamis (16.9%). At present, however, international relief efforts might reduce the effects of post-eruption crop failure and disease, and at least some of the lahars could be anticipated in time by adequate scientific and social response. Thus, mitigation of hazards from pyroclastic flows and tsunamis will become of paramount importance to volcanologists and civil authorities.

  12. Volcanic Lightning in Eruptions of Sakurajima Volcano

    NASA Astrophysics Data System (ADS)

    Edens, Harald; Thomas, Ronald; Behnke, Sonja; McNutt, Stephen; Smith, Cassandra; Farrell, Alexandra; Van Eaton, Alexa; Cimarelli, Corrado; Cigala, Valeria; Eack, Ken; Aulich, Graydon; Michel, Christopher; Miki, Daisuke; Iguchi, Masato

    2016-04-01

    In May 2015 a field program was undertaken to study volcanic lightning at the Sakurajima volcano in southern Japan. One of the main goals of the study was to gain a better understanding of small electrical discharges in volcanic eruptions, expanding on our earlier studies of volcanic lightning at Augustine and Redoubt volcanoes in Alaska, USA, and Eyjafjallajökull in Iceland. In typical volcanic eruptions, electrical activity occurs at the onset of an eruption as a near-continual production of VHF emissions at or near to the volcanic vent. These emissions can occur at rates of up to tens of thousands of emissions per second, and are referred to as continuous RF. As the ash cloud expands, small-scale lightning flashes of several hundred meters length begin to occur while the continuous RF ceases. Later on during the eruption larger-scale lightning flashes may occur within the ash cloud that are reminiscent of regular atmospheric lightning. Whereas volcanic lightning flashes are readily observed and reasonably well understood, the nature and morphology of the events producing continuous RF are unknown. During the 2015 field program we deployed a comprehensive set of instrumentation, including a 10-station 3-D Lightning Mapping Array (LMA) that operated in 10 μs high time resolution mode, slow and fast ΔE antennas, a VHF flat-plate antenna operating in the 20-80 MHz band, log-RF waveforms within the 60-66 MHz band, an infra-red video camera, a high-sensitivity Watec video camera, two high-speed video cameras, and still cameras. We give an overview of the Sakurajima field program and present preliminary results using correlated LMA, waveforms, photographs and video recordings of volcanic lightning at Sakurajima volcano.

  13. A solar eruption driven by rapid sunspot rotation

    SciTech Connect

    Ruan, Guiping; Chen, Yao; Du, Guohui; Wang, Shuo; Jing, Ju; Wang, Haimin; Zhang, Hongqi; Su, Jiangtao; Xu, Haiqing; Li, Gang; Li, Xing

    2014-04-01

    We present the observation of a major solar eruption that is associated with fast sunspot rotation. The event includes a sigmoidal filament eruption, a coronal mass ejection, and a GOES X2.1 flare from NOAA active region 11283. The filament and some overlying arcades were partially rooted in a sunspot. The sunspot rotated at ∼10° hr{sup –1} during a period of 6 hr prior to the eruption. In this period, the filament was found to rise gradually along with the sunspot rotation. Based on the Helioseismic and Magnetic Imager observation, for an area along the polarity inversion line underneath the filament, we found gradual pre-eruption decreases of both the mean strength of the photospheric horizontal field (B{sub h} ) and the mean inclination angle between the vector magnetic field and the local radial (or vertical) direction. These observations are consistent with the pre-eruption gradual rising of the filament-associated magnetic structure. In addition, according to the nonlinear force-free field reconstruction of the coronal magnetic field, a pre-eruption magnetic flux rope structure is found to be in alignment with the filament, and a considerable amount of magnetic energy was transported to the corona during the period of sunspot rotation. Our study provides evidence that in this event sunspot rotation plays an important role in twisting, energizing, and destabilizing the coronal filament-flux rope system, and led to the eruption. We also propose that the pre-event evolution of B{sub h} may be used to discern the driving mechanism of eruptions.

  14. High-Resolution Observations of Sympathetic Filament Eruptions by NVST

    NASA Astrophysics Data System (ADS)

    Su, Yingna; Li, Shangwei; Zhou, Tuanhui; Ji, Haisheng

    2016-05-01

    We investigate the sympathetic eruptions of two solar filaments side by side as observed by the New Vacuum Solar Telescope (NVST) on 2015 October 15. These two filaments start from the complex active region NOAA 12434 (north) and end in a large quiescent region (south). The corresponding SDO/HMI magnetic field observations suggest that the two small filaments are located above two different polarity inversion lines in the northern part. The SDO/AIA observations of the eruption show that these two filaments appear to merge into one in the southern quiescent region. The north-eastern filament starts eruption firstly, which is followed by the north-western filament eruption about 20 minutes later. Clear untwisting motions (i.e., signature of flux ropes) are observed in both filaments during the eruption. After the lifts off of the north-western filament, mini filaments are observed to emerge from the surface and rise up multiple times. The high-resolution observations reveal the fact that the filament is composed of multiple sections and multiple layers. The filament in the lower layer can merge into the upper layer, which leads to the increase of non-potentiality of the upper layer. Magnetic field models using the flux rope insertion method are also constructed in order to understand the complex magnetic configuration as well as the initiation and dynamics of the eruptions.

  15. Risk factors for seabather's eruption: a prospective cohort study.

    PubMed Central

    Kumar, S; Hlady, W G; Malecki, J M

    1997-01-01

    OBJECTIVE: A prospective cohort study was performed to identify risk factors for seabather's eruption. METHODS: Study participants were recruited at four beaches in Palm Beach County, Florida, during three weekends of May and June 1993. Participants were interviewed by telephone after 48 hours regarding medical history, beach activities, development of rashes, and use of possible preventive measures. RESULTS: Seabather's eruption, defined by the occurrence of a rash within two days of exposure to seawater, was reported by 114 (16%) of 735 respondents. The strongest predictor of seabather's eruption was a past history of the condition. Children less than 16 years of age were also at increased risk, as were surfers. Showering with one's bathing suit off was a useful protective measure. CONCLUSION: The study's findings suggest that when the seasonal risk of seabather's eruption is present, children, people with a history of seabather's eruption, and surfers are at greatest risk. During the sea lice season, seabathers can minimize their risk by showering with their bathing suits off after seabathing. Length of the time spent in water was not significantly associated with seabather's eruption. PMID:9018290

  16. Automated Detection of Eruptive Structures for Solar Eruption Prediction

    NASA Astrophysics Data System (ADS)

    Georgoulis, Manolis K.

    2012-07-01

    The problem of data processing and assimilation for solar eruption prediction is, for contemporary solar physics, more pressing than the problem of data acquisition. Although critical solar data, such as the coronal magnetic field, are still not routinely available, space-based observatories deliver diverse, high-quality information at such a high rate that a manual or semi-manual processing becomes meaningless. We discuss automated data analysis methods and explain, using basic physics, why some of them are unlikely to advance eruption prediction. From this finding we also understand why solar eruption prediction is likely to remain inherently probabilistic. We discuss some promising eruption prediction measures and report on efforts to adapt them for use with high-resolution, high-cadence photospheric and coronal data delivered by the Solar Dynamics Observatory. Concluding, we touch on the problem of physical understanding and synthesis of different results: combining different measures inferred by different data sets is a yet-to-be-done exercise that, however, presents our best opportunity of realizing benefits in solar eruption prediction via a meaningful, targeted assimilation of solar data.

  17. Eruptive history and magmatic stability of Erebus volcano, Antarctica: Insights from englacial tephra

    NASA Astrophysics Data System (ADS)

    Iverson, Nels A.; Kyle, Philip R.; Dunbar, Nelia W.; McIntosh, William C.; Pearce, Nicholas J. G.

    2014-11-01

    tephrostratigraphy of the active Antarctic Erebus volcano was determined from englacial tephra on the ice-covered flanks of Erebus and an adjacent volcano. The tephra are used to reconstruct the eruptive history and magmatic evolution of Erebus. More fine-grained and blocky particles define tephra formed in phreatomagmatic eruptions and larger fluidal shards are characteristic of magmatic eruptions and in some cases both eruptive types are identified in a single mixed tephra. The eruptions forming the mixed tephra likely started as phreatomagmatic eruptions which transitioned into Strombolian eruptions as the nonmagmatic water source was exhausted. We reconstructed the eruptive history of Erebus using the tephra layers stratigraphic position, 40Ar/39Ar ages, shard morphology, and grain size. Major and trace element analyses of individual glass shards were measured by electron probe microanalysis and LA-ICP-MS. Trachybasalt, trachyte, and phonolite tephra were identified. All phonolitic tephra are Erebus-derived with compositions similar to volcanic bombs erupted from Erebus over the past 40 years. The tephra show that Erebus magma has not significantly changed for 40 ka. The uniformity of the glass chemical composition implies that the phonolite magma has crystallized in the same manner without change throughout the late Quaternary, suggesting long-term stability of the Erebus magmatic system. Trachyte and trachybasalt tephra were likely erupted from Marie Byrd Land and the McMurdo Sound area, respectively. The trachytic tephra can be regionally correlated and could provide an important time-stratigraphic marker in Antarctic ice cores.

  18. Dental eruption in afrotherian mammals

    PubMed Central

    Asher, Robert J; Lehmann, Thomas

    2008-01-01

    Background Afrotheria comprises a newly recognized clade of mammals with strong molecular evidence for its monophyly. In contrast, morphological data uniting its diverse constituents, including elephants, sea cows, hyraxes, aardvarks, sengis, tenrecs and golden moles, have been difficult to identify. Here, we suggest relatively late eruption of the permanent dentition as a shared characteristic of afrotherian mammals. This characteristic and other features (such as vertebral anomalies and testicondy) recall the phenotype of a human genetic pathology (cleidocranial dysplasia), correlations with which have not been explored previously in the context of character evolution within the recently established phylogeny of living mammalian clades. Results Although data on the absolute timing of eruption in sengis, golden moles and tenrecs are still unknown, craniometric comparisons for ontogenetic series of these taxa show that considerable skull growth takes place prior to the complete eruption of the permanent cheek teeth. Specimens showing less than half (sengis, golden moles) or two-thirds (tenrecs, hyraxes) of their permanent cheek teeth reach or exceed the median jaw length of conspecifics with a complete dentition. With few exceptions, afrotherians are closer to median adult jaw length with fewer erupted, permanent cheek teeth than comparable stages of non-afrotherians. Manatees (but not dugongs), elephants and hyraxes with known age data show eruption of permanent teeth late in ontogeny relative to other mammals. While the occurrence of delayed eruption, vertebral anomalies and other potential afrotherian synapomorphies resemble some symptoms of a human genetic pathology, these characteristics do not appear to covary significantly among mammalian clades. Conclusion Morphological characteristics shared by such physically disparate animals such as elephants and golden moles are not easy to recognize, but are now known to include late eruption of permanent teeth, in

  19. An investigation of pre-eruptive deformation for the 2004 eruption of Mount St. Helens using persistent scatterer interferometry

    NASA Astrophysics Data System (ADS)

    Welch, M.; Schmidt, D. A.

    2014-12-01

    The volcanoes of the Cascade Range pose a legitimate threat to people living in the Pacific Northwest. Mt St Helens, which erupted in 2004 as a part of a dome building event, is a notable example of this danger. Deformation and seismicity are known indicators of volcanic activity and can provide warning of an imminent eruption. In the weeks leading up to the 2004 eruption, a shallow earthquake swarm was detected under St. Helens, suggesting ongoing deformation with its source beneath the edifice. A campaign GPS survey conducted in 2000 found no evidence of deformation. The sole continuous GPS station that was operational prior to the eruption (located ~9 km away from the crater) began moving only with the onset of the earthquake swarm. Because of the lack of ground based geodetic instruments in the near-field of Mt St Helens at the time of the 2004 eruption, it is unknown whether pre-eruptive deformation occurred on the edifice or solely within crater. InSAR is the only method available to conclusively determine whether the 2004 eruption was preceded by deformation of the edifice. Previous work explored this question using standard 2-pass interferometry, but the results were inconclusive. The main obstacle to implementing InSAR methods in the Cascades region is phase decorrelation due to the presence of both dense forest and snow for most of the year. We revisit the available InSAR data for St. Helens by experimenting with the application of the Persistent Scatterers and Distributed Scatterers processing techniques in order to overcome the decorrelation problem. By using these techniques on the question of Mt St Helens pre-eruptive deformation, we will demonstrate the viability of their application to the entire Northwest region as a low cost, low maintenance, monitoring tool.

  20. Forecasting volcanic ash dispersal and coeval resuspension during the April-May 2015 Calbuco eruption

    NASA Astrophysics Data System (ADS)

    Reckziegel, F.; Bustos, E.; Mingari, L.; Báez, W.; Villarosa, G.; Folch, A.; Collini, E.; Viramonte, J.; Romero, J.; Osores, S.

    2016-07-01

    Atmospheric dispersion of volcanic ash from explosive eruptions or from subsequent fallout deposit resuspension causes a range of impacts and disruptions on human activities and ecosystems. The April-May 2015 Calbuco eruption in Chile involved eruption and resuspension activities. We overview the chronology, effects, and products resulting from these events, in order to validate an operational forecast strategy for tephra dispersal. The modelling strategy builds on coupling the meteorological Weather Research and Forecasting (WRF/ARW) model with the FALL3D dispersal model for eruptive and resuspension processes. The eruption modelling considers two distinct particle granulometries, a preliminary first guess distribution used operationally when no field data was available yet, and a refined distribution based on field measurements. Volcanological inputs were inferred from eruption reports and results from an Argentina-Chilean ash sample data network, which performed in-situ sampling during the eruption. In order to validate the modelling strategy, results were compared with satellite retrievals and ground deposit measurements. Results indicate that the WRF-FALL3D modelling system can provide reasonable forecasts in both eruption and resuspension modes, particularly when the adjusted granulometry is considered. The study also highlights the importance of having dedicated datasets of active volcanoes furnishing first-guess model inputs during the early stages of an eruption.

  1. Kamchatkan Volcanic Eruption Response Team (KVERT), Russia: preventing the danger of volcanic eruptions to aviation.

    NASA Astrophysics Data System (ADS)

    Girina, O.; Neal, Ch.

    2012-04-01

    The Kamchatkan Volcanic Eruption Response Team (KVERT) has been a collaborative project of scientists from the Institute of Volcanology and Seismology, the Kamchatka Branch of Geophysical Surveys, and the Alaska Volcano Observatory (IVS, KB GS and AVO). The purpose of KVERT is to reduce the risk of costly, damaging, and possibly deadly encounters of aircraft with volcanic ash clouds. To reduce this risk, KVERT collects all possible volcanic information and issues eruption alerts to aviation and other emergency officials. KVERT was founded by Institute of Volcanic Geology and Geochemistry FED RAS in 1993 (in 2004, IVGG merged with the Institute of Volcanology to become IVS). KVERT analyzes volcano monitoring data (seismic, satellite, visual and video, and pilot reports), assigns the Aviation Color Code, and issues reports on eruptive activity and unrest at Kamchatkan (since 1993) and Northern Kurile (since 2003) volcanoes. KVERT receives seismic monitoring data from KB GS (the Laboratory for Seismic and Volcanic Activity). KB GS maintains telemetered seismic stations to investigate 11 of the most active volcanoes in Kamchatka. Data are received around the clock and analysts evaluate data each day for every monitored volcano. Satellite data are provided from several sources to KVERT. AVO conducts satellite analysis of the Kuriles, Kamchatka, and Alaska as part of it daily monitoring and sends the interpretation to KVERT staff. KVERT interprets MODIS and MTSAT images and processes AVHRR data to look for evidence of volcanic ash and thermal anomalies. KVERT obtains visual volcanic information from volcanologist's field trips, web-cameras that monitor Klyuchevskoy (established in 2000), Sheveluch (2002), Bezymianny (2003), Koryaksky (2009), Avachinsky (2009), Kizimen (2011), and Gorely (2011) volcanoes, and pilots. KVERT staff work closely with staff of AVO, AMC (Airport Meteorological Center) at Yelizovo Airport and the Tokyo Volcanic Ash Advisory Center (VAAC), the

  2. Iceland's Grímsvötn volcano erupts

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-05-01

    About 13 months after Iceland's Eyjafjallajökull volcano began erupting on 14 April 2010, which led to extensive air traffic closures over Europe, Grímsvötn volcano in southeastern took its turn. Iceland's most active volcano, which last erupted in 2004 and lies largely beneath the Vatnajökull ice cap, began its eruption activity on 21 May, with the ash plume initially reaching about 20 kilometers in altitude, according to the Icelandic Meteorological Office. Volcanic ash from Grímsvötn has cancelled hundreds of airplane flights and prompted U.S. president Barack Obama to cut short his visit to Ireland. As Eos went to press, activity at the volcano was beginning to subside.

  3. Eruption cysts in the neonate.

    PubMed

    Ricci, Hérica Adad; Parisotto, Thaís Manzano; Giro, Elisa Maria Aparecida; de Souza Costa, Carlos Alberto; Hebling, Josimeri

    2008-01-01

    Disturbances of the dental development may result in anomalies, which may be apparent as soon as the child is born. Eruption cysts are rarely observed in neonates considering that at this stage of the child's life teeth eruption is uncommon. Thus, the aim of this report is to describe a case of eruption cysts in a neonate. A male neonate was brought to the emergency service with the chief complaint of an elevated area on the anterior region of the inferior alveolar ridge. The lesion was clinically characterized as a compressive and floating swelling. Through a radiographic exam two mandibular primary incisors could be seen superficially located. Due to the patient's age and the initial diagnosis of eruption cysts the conduct adopted was clinical surveillance. Forty-five days after the first visit the lesions had significantly decreased in size, and completely disappeared after 4 months. At that age, both mandibular central incisors were already in the oral cavity exhibiting small hypoplastic areas in the incisal edges. The clinical and radiographic follow-up of eruption cysts in neonates appears to be an adequate conduct without differing from that recommended for older children. PMID:18524277

  4. Featured Image: Solar Prominence Eruptions

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-02-01

    In these images from the Solar Dynamics Observatorys AIA instrument (click for the full resolution!), two solar prominence eruptions (one from June 2011 and one from August 2012) are shown in pre- and post-eruption states. The images at the top are taken in the Fe XII 193 bandpass and the images at the bottom are taken in the He II 304 bandpass. When a team of scientists searched through seven years of solar images taken by the STEREO (Solar Terrestrial Relations Observatory) spacecraft, these two eruptions were found to extend all the way out to a distance of 1 AU. They were the only two examples of clear, bright, and compact prominence eruptions found to do so. The scientists, led by Brian Wood (Naval Research Laboratory), used these observations to reconstruct the motion of the eruption and model how prominences expand as they travel away from the Sun. Theimage to the rightshowsa STEREO observation compared to the teams 3D model of theprominences shape and expansion. To learn more about theresults from this study, check out the paper below.CitationBrian E. Wood et al 2016 ApJ 816 67. doi:10.3847/0004-637X/816/2/67

  5. Automated detection of solar eruptions

    NASA Astrophysics Data System (ADS)

    Hurlburt, N.

    2015-12-01

    Observation of the solar atmosphere reveals a wide range of motions, from small scale jets and spicules to global-scale coronal mass ejections (CMEs). Identifying and characterizing these motions are essential to advancing our understanding of the drivers of space weather. Both automated and visual identifications are currently used in identifying Coronal Mass Ejections. To date, eruptions near the solar surface, which may be precursors to CMEs, have been identified primarily by visual inspection. Here we report on Eruption Patrol (EP): a software module that is designed to automatically identify eruptions from data collected by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory (SDO/AIA). We describe the method underlying the module and compare its results to previous identifications found in the Heliophysics Event Knowledgebase. EP identifies eruptions events that are consistent with those found by human annotations, but in a significantly more consistent and quantitative manner. Eruptions are found to be distributed within 15 Mm of the solar surface. They possess peak speeds ranging from 4 to 100 km/s and display a power-law probability distribution over that range. These characteristics are consistent with previous observations of prominences.

  6. Volatiles from the 1994 Eruptions of Rabaul: Understanding Large Caldera Systems

    PubMed

    Roggensack; Williams; Schaefer; Parnell

    1996-07-26

    The 1994 eruption of Rabaul, in Papua New Guinea, involved a small plinian eruption at Vulcan and a vulcanian eruption on the opposite side of the caldera at Tavurvur. Vulcan's ash leachates indicate seawater interaction that is consistent with earlier observations of low sulfur dioxide emissions and the presence of ice crystals in the initial plinian eruption cloud. In contrast, Tavurvur ash leachates indicate no seawater interaction, and later sulfur dioxide emissions remained high despite low-level eruptive activity. Silicic melt inclusions indicate that the andesitic melt contained about 2 weight percent water and negligible carbon dioxide. Mafic melt inclusions in Tavurvur ash have water and carbon dioxide contents that vary systematically over the course of the eruption. The mafic melt inclusions suggest that a mafic dike intruded from below the silicic chamber and provide further evidence that mafic intrusions drive caldera unrest. PMID:8662536

  7. Long-range infrasound monitoring of eruptive volcanoes.

    NASA Astrophysics Data System (ADS)

    Marchetti, Emanuele; Innocenti, Lorenzo; Ulivieri, Giacomo; Lacanna, Giorgio; Ripepe, Maurizio

    2016-04-01

    The efficient long-range propagation in the atmosphere makes infrasound of active volcanoes extremely promising and opens new perspectives for volcano monitoring at large scale. In favourable propagation conditions, long-range infrasound observations can be used to track the occurrence and the duration of volcanic eruptions also at remote non-monitored volcanoes, but its potential to infer volcanic eruptive source term is still debated. We present results of comparing five years of infrasound of eruptive activity at Mt.Etna volcano (Italy) recorded both at local (~5 km) and at regional distances (~600 km) from the source. Infrasound of lava fountains at Etna volcano, occurring in between 2010 and 2015, are analysed in terms of the local and regional wavefield record, and by comparing to all available volcanic source terms (i.e. plume height and mass eruption rates). Besides, the potential of near real-time notification of ongoing volcanic activity at Etna volcano at a regional scale is investigated. In particular we show how long range infrasound, in the case of Etna volcano, can be used to promptly deliver eruption notification and reliability is constrained by the results of the local array. This work is performed in the framework of the H2020 ARISE2 project funded by the EU in the period 2015-2018.

  8. Mechanism of explosive eruptions of Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Dvorak, J.J.

    1992-01-01

    A small explosive eruption of Kilauea Volcano, Hawaii, occurred in May 1924. The eruption was preceded by rapid draining of a lava lake and transfer of a large volume of magma from the summit reservoir to the east rift zone. This lowered the magma column, which reduced hydrostatic pressure beneath Halemaumau and allowed groundwater to flow rapidly into areas of hot rock, producing a phreatic eruption. A comparison with other events at Kilauea shows that the transfer of a large volume of magma out of the summit reservoir is not sufficient to produce a phreatic eruption. For example, the volume transferred at the beginning of explosive activity in May 1924 was less than the volumes transferred in March 1955 and January-February 1960, when no explosive activity occurred. Likewise, draining of a lava lake and deepening of the floor of Halemaumau, which occurred in May 1922 and August 1923, were not sufficient to produce explosive activity. A phreatic eruption of Kilauea requires both the transfer of a large volume of magma from the summit reservoir and the rapid removal of magma from near the surface, where the surrounding rocks have been heated to a sufficient temperature to produce steam explosions when suddenly contacted by groundwater. ?? 1992 Springer-Verlag.

  9. A sight "fearfully grand": eruptions of Lassen Peak, California, 1914 to 1917

    USGS Publications Warehouse

    Clynne, Michael A.; Christiansen, Robert L.; Stauffer, Peter H.; Hendley, James W., II; Bleick, Heather A.

    2014-01-01

    On May 22, 1915, a large explosive eruption at the summit of Lassen Peak, California, the southernmost active volcano in the Cascade Range, devastated nearby areas and rained volcanic ash as far away as 280 miles to the east. This explosion was the most powerful in a series of eruptions during 1914–17 that were the last to occur in the Cascade Range before the 1980 eruption of Mount St. Helens, Washington. A century after the Lassen eruptions, work by U.S. Geological Survey (USGS) scientists in cooperation with the National Park Service is shedding new light on these events.

  10. Eruption of soufriere volcano on st. Vincent island, 1971-1972.

    PubMed

    Aspinall, W P; Sigurdsson, H; Shepherd, J B

    1973-07-13

    The Soufrière volcano in St. Vincent erupted from October 1971 to March 1972, as 80 x 10(6) m(3) of basaltic andesite lava was quietly extruded inside the mile-wide crater. The eruption was largely subaqueous, taking place in the 180-m-deep crater lake, and resulted in the emergence of a steep-sided island. The mild character of the eruption and the absence of seismic activity stand in direct contrast to the highly explosive character of the eruption of 1902 to 1903. PMID:17746610

  11. Keck observations of eruptions on Io in 2003-2005

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Davies, Ashley Gerard; Marchis, Franck

    2016-08-01

    We report observations of four energetic volcanic eruptions on Io: at Tupan Patera on UT 8 March 2003; Tung Yo Patera on UT 28 May 2004; Sui Jen Patera on UT 30 May 2004; and south of Babbar Patera on UT 31 May 2005. The Tung Yo, Sui Jen and south of Babbar Paterae eruptions are in locations where no activity had been seen before. Our observations were obtained at near-infrared wavelengths (1.2-4.7 μm) with the 10-m Keck telescope equipped with adaptive optics. We report single and two-temperature blackbody fits, as well as single-component and dual-component Io Flow Model (IFM) fits (Davies, 1996, Icarus, 124, 45-61) to all four eruptions where applicable. We use 2-μm and 5-μm radiant fluxes, the 2:5-μm radiant flux ratio, and radiant flux density of each thermal source to constrain the likely style of volcanic eruption. All eruptions are characterized by a high temperature IFM component (ranging from 1475 to ∼900 K) from a relatively small area (<1 km2 to several tens of km2), and a lower temperature component with a more extensive surface area. The relationship of the areas at the highest temperatures to the cooler, more extensive area is of particular importance in deriving eruption style. Model fits to the Sui Jen Patera data are strongly suggestive of lava fountaining, although not at a level consistent with a large "outburst" eruption. Activity at Tupan Patera suggests that the entire floor of the patera may have been resurfaced with silicate lava in 2003.

  12. Eruptive history of South Sister, Oregon Cascades

    USGS Publications Warehouse

    Fierstein, J.; Hildreth, W.; Calvert, A.T.

    2011-01-01

    South Sister locus throughout its lifetime. South Sister is part of a reach of the Cascades unusually active in the last 50kyr, characterized by high vent density, N-S vent alignments, and numerous eruptive units of true rhyolite (≥ 72% SiO2) that distinguishes it from much of the Quaternary Cascade arc; these are eruptive expressions of the complex confluence of arc and intraplate magmatic-tectonic regimes.

  13. Pre-eruptive volatile content, degassing paths and depressurisation explaining the transition in style at the subglacial rhyolitic eruption of Dalakvísl, South Iceland

    NASA Astrophysics Data System (ADS)

    Owen, Jacqueline; Tuffen, Hugh; McGarvie, David W.

    2013-05-01

    Many volcanoes express a variety of contrasting eruptive styles with behavioural transitions between explosive and effusive activities. Understanding eruptive mechanisms is of key importance but we currently have little insight into the behavioural controls for rhyolitic eruptions beneath ice. This paper addresses a subglacial rhyolitic eruption at Dalakvísl in South Iceland that involved both explosive and effusive activities. We present measurements of pre- and post-eruptive magmatic volatile contents that we use to track magma degassing from the chamber to the surface and reconstruct pressure conditions during the eruption. Explosive and effusive phases involve significant differences in: (1) pre-eruptive volatile contents; (2) the ‘openness' of magma degassing; and (3) inferred confining pressure. This final factor is potentially associated with a jökulhlaup-induced decompression. Due to the combination of these factors Dalakvísl experienced a change from effusive to explosive behaviour, although we cannot currently resolve cause from effect. Our work points towards complex interactions between the dynamics of magma ascent and the response of overlying ice and meltwater during rhyolitic eruptions beneath ice.

  14. Potential hazards from future volcanic eruptions in California

    USGS Publications Warehouse

    Miller, C. Dan

    1989-01-01

    More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the last 10,000 years. Past volcanic activity has ranged in scale and type from small rhyolitic and basaltic eruptions through large catastrophic rhyolitic eruptions. Sooner or later, volcanoes in California will erupt again, and they could have serious impacts on the health and safety of the State\\'s citizens as well as on its economy. This report describes the nature and probable distribution of potentially hazardous volcanic phenomena and their threat to people and property. It includes hazard-zonation maps that show areas relatively likely to be affected by future eruptions in California. The potentially more hazardous eruptions in the State are those that involve explosive eruption of large volumes of silicic magma. Such eruptions could occur at vents in as many as four areas in California. They could eject pumice high into the atmosphere above the volcano, produce destructive blasts, avalanches, or pyroclastic flows that reach distances of tens of kilometers from a vent, and produce mudflows and floods that reach to distances of hundreds of kilometers. Smaller eruptions produce similar, but less severe and less extensive, phenomena. Hazards are greatest close to a volcanic vent; the slopes on or near a volcano, and valleys leading away from it, are affected most often and most severely by such eruptions. In general, risk from volcanic phenomena decreases with increasing distance from a vent and, for most flowage processes, with increasing height above valley floors or fan surfaces. Tephra (ash) from explosive eruptions can affect wide areas downwind from a vent. In California, prevailing winds cause the 180-degree sector east of the volcano to be affected most often and most severely. Risk to life from ashfall decreases rapidly with increasing distance from a vent, but thin deposits of ash could disrupt communication

  15. Can the structure of an explosive caldera affect eruptive behaviour?

    NASA Astrophysics Data System (ADS)

    Willcox, C. P.; Branney, M.; Carrasco-Nuñez, G.; Barford, D.

    2010-12-01

    Explosive caldera volcanoes cause catastrophic events at the Earth’s surface, yet we know little about how their internal structures evolve with time, and whether this can affect both differentiation and eruptive behaviour. Distinguishing how structural evolution impacts upon eruption behaviour and periodicity is challenging because the resolution of eruption frequencies can be difficult at ancient exhumed calderas, whereas at young volcanoes, most of the caldera floor faults and associated conduits are hidden. Some exhumed calderas reveal caldera floor faults and conduits; some of these apparently underwent a single collapse event that was piecemeal, i.e. fragmentation into several, variously subsided fault-blocks (e.g. Scafell caldera, UK). In contrast, the present study tests whether some caldera volcanoes may become more intensely fractured with time as a result of successive distinct caldera-collapse eruptions (“multi-cyclic calderas”). It has been proposed that this scenario could lead to an increase in eruption frequency, with smaller eruptions over time. Magma leakage through the increasingly fractured volcano might also lead to less evolved compositions with time due to shorter residence times. We have returned to the volcano where this hypothesis was formulated, the ~ 20 km diameter, hydrothermally active Los Humeros caldera in eastern central México. We aim to see how well the structural evolution of this modern caldera can be reconstructed, and whether changes in structure affected the styles and periodicity of large explosive eruptions. How a caldera evolves structurally could have important implications for predicting future catastrophic eruptions. Detailed structural mapping (e.g. of fault scarps, vent positions, and tilted strata), documentation of draping and cross-cutting field relations, together with logging, optical and SEM petrography, XRF major and trace element geochemistry and new 40Ar-39Ar and radiocarbon dating of the pyroclastic

  16. A tale of two seafloor eruptions: Comparing seismic data from the 2006 East Pacific Rise and 2015 Axial Seamount eruptions

    NASA Astrophysics Data System (ADS)

    Tolstoy, M.; Wilcock, W. S. D.; Tan, Y. J.; Waldhauser, F.

    2015-12-01

    In January 2006 at 9°50'N on the East Pacific Rise, a three-OBS array captured the first in situ seismic data from a mid-ocean ridge eruption. The data show a steady build up in seismicity over the preceding 2+ years leading to a seismic crisis on January 22nd2006 that lasted approximately 6 hours, with one particularly intense hour interpreted as a rising dike (Tolstoy et al., 2006). This was followed by approximately 10 days of dwindling activity. In April-May 2015, at the ridge-hotspot Axial Seamount, an eight-OBS array captured the second in situ seismic data, and first real-time data, from a mid-ocean ridge eruption. This eruption was also preceded by high seismicity rates, though data were only available for ~6 months prior to the eruption. An ~10 hr seismic crisis on April 24thwas followed by almost a month of dwindling activity. Immediately following the end of the crisis, previously unknown impulsive waterborne signals were observed coming from two sites along the north rift of Axial Seamount (Wilcock et al., this meeting; Garcia et al., this meeting). The signals were interpreted as being associated with lava reaching the seafloor, and subsequent multibeam mapping and an ROV dive confirmed the presence of fresh lava at these sites (Kelley et al., this meeting). Re-examination of the East Pacific Rise eruption data has shown that the same impulsive waterborne signals were also observed there starting ~3 hrs after the beginning of the 2006 seismic crisis (Tan et al., this meeting). The locations of these signals track the mapped lava flow associated with this eruption (Soule et al., 2007), further supporting their association with lava extrusion onto the seafloor. These two eruptions show similar characteristics including ~6-10 hr seismic crises, and lava likely reaching the surface within ~3 hrs (EPR) and ~10 hrs (Axial) of the initiation of seismic crisis activity. They also show similar tremor activity, likely suggesting similar magma movement processes

  17. Erupted odontoma: a case report.

    PubMed

    Raval, Nilesh; Mehta, Dhaval; Vachhrajani, Kanan; Nimavat, Abhishek

    2014-07-01

    Odontomas are nonaggressive, hamartomatous developmental malformations or lesions of odontogenic origin, which consist of enamel, dentin, cementum and pulpal tissue 'Erupted odontoma' is a term used to specifically denote odontomas, which are exposed into the oral cavity. These are rare entities with only 25-30 cases being reported so far in the dental literature. Here, we present a rare case of an erupted odontoma in an adolescent patient who came with a complaint of bad aesthetics due to the presence of multiple small teeth like structures in the upper front teeth region. PMID:25177649

  18. Sub-glacial volcanic eruptions

    USGS Publications Warehouse

    White, Donald Edward

    1956-01-01

    The literature on sub-glacial volcanic eruptions and the related flood phenomena has been reviewed as a minor part of the larger problem of convective and conductive heat transfer from intrusive magma. (See Lovering, 1955, for a review of the extensive literature on this subject.) This summary of data on sub-glacial eruptions is part of a program that the U.S. Geological Survey is conducting in connection with its Investigations of Geologic Processes project on behalf of the Division of Research, U.S. Atomic Energy Commission.

  19. The intensities and magnitudes of volcanic eruptions

    USGS Publications Warehouse

    Sigurdsson, H.

    1991-01-01

    Ever since 1935, when C.F Richter devised the earthquake magnitude scale that bears his name, seismologists have been able to view energy release from earthquakes in a systematic and quantitative manner. The benefits have been obvious in terms of assessing seismic gaps and the spatial and temporal trends of earthquake energy release. A similar quantitative treatment of volcanic activity is of course equally desirable, both for gaining a further understanding of the physical principles of volcanic eruptions and for volcanic-hazard assessment. A systematic volcanologic data base would be of great value in evaluating such features as volcanic gaps, and regional and temporal trends in energy release.  

  20. Multi-parameter quantification of wet eruption dynamics (Invited)

    NASA Astrophysics Data System (ADS)

    Schipper, C.; Burgisser, A.; Le Voyer, M.; White, J. D.

    2013-12-01

    Processes observed during the extremely well documented eruption of Surtsey, Iceland (1963-67), highlighted that magma-water interaction affects eruption dynamics. Although 2013 marks the 50th anniversary of this canonical eruption, many specific aspects of Surtseyan eruption dynamics, and magma-water interaction in general, remain only qualitatively described. For example, eruptions or phases thereof are often referred to as 'phreatomagmatic', without any discussion or identification of specific geometries and interactive volumes of the magma-water interaction involved. Moving toward a more quantitative understanding requires that all types of information: observational, textural, geochemical, and thermodynamic, be combined to effectively normalize the heterogeneity that is inherent to wet eruptions, and to yield specific descriptors of how magma and water (+/- solid contaminants) interact in style-defining ways. We explore the hypothesis that Surtseyan dynamics result from mingling between actively degassing and vesiculating magma, and slurries of previously erupted material in a flooded vent. Magmatic textures and properties can be explained by co-tracking: volatiles in phenocryst-hosted melt inclusions, the composition of gases emitted during the eruption, and evolution of magma porosity/permeability. Mingling of magma with water-saturated slurry can be identified in the textures of compound clasts over a range of grain sizes. Depending on key mingling parameters, including: the magma's porosity/permeability, the magma-slurry mixing ratio, and the slurry's particle-water mass ratio, several characteristic features of Surtseyan eruptions can be explained. The low-pressure expansion of superheated water in a coarsely mingled, saturated slurry can initiate Surtseyan cock's tail jets by imparting momentum to composite bombs at the jets' leading edges. Finer-scale mingling ensures that vapour formed within ballistic bombs discharges over timescales longer than their

  1. Curtain eruptions from Enceladus' south-polar terrain.

    PubMed

    Spitale, Joseph N; Hurford, Terry A; Rhoden, Alyssa R; Berkson, Emily E; Platts, Symeon S

    2015-05-01

    Observations of the south pole of the Saturnian moon Enceladus revealed large rifts in the south-polar terrain, informally called 'tiger stripes', named Alexandria, Baghdad, Cairo and Damascus Sulci. These fractures have been shown to be the sources of the observed jets of water vapour and icy particles and to exhibit higher temperatures than the surrounding terrain. Subsequent observations have focused on obtaining close-up imaging of this region to better characterize these emissions. Recent work examined those newer data sets and used triangulation of discrete jets to produce maps of jetting activity at various times. Here we show that much of the eruptive activity can be explained by broad, curtain-like eruptions. Optical illusions in the curtain eruptions resulting from a combination of viewing direction and local fracture geometry produce image features that were probably misinterpreted previously as discrete jets. We present maps of the total emission along the fractures, rather than just the jet-like component, for five times during an approximately one-year period in 2009 and 2010. An accurate picture of the style, timing and spatial distribution of the south-polar eruptions is crucial to evaluating theories for the mechanism controlling the eruptions. PMID:25951283

  2. Curtain eruptions from Enceladus' south-polar terrain

    NASA Astrophysics Data System (ADS)

    Spitale, Joseph N.; Hurford, Terry A.; Rhoden, Alyssa R.; Berkson, Emily E.; Platts, Symeon S.

    2015-05-01

    Observations of the south pole of the Saturnian moon Enceladus revealed large rifts in the south-polar terrain, informally called `tiger stripes', named Alexandria, Baghdad, Cairo and Damascus Sulci. These fractures have been shown to be the sources of the observed jets of water vapour and icy particles and to exhibit higher temperatures than the surrounding terrain. Subsequent observations have focused on obtaining close-up imaging of this region to better characterize these emissions. Recent work examined those newer data sets and used triangulation of discrete jets to produce maps of jetting activity at various times. Here we show that much of the eruptive activity can be explained by broad, curtain-like eruptions. Optical illusions in the curtain eruptions resulting from a combination of viewing direction and local fracture geometry produce image features that were probably misinterpreted previously as discrete jets. We present maps of the total emission along the fractures, rather than just the jet-like component, for five times during an approximately one-year period in 2009 and 2010. An accurate picture of the style, timing and spatial distribution of the south-polar eruptions is crucial to evaluating theories for the mechanism controlling the eruptions.

  3. Continuous soil radon monitoring during the July 2006 Etna eruption

    NASA Astrophysics Data System (ADS)

    Neri, M.; Behncke, B.; Burton, M.; Galli, G.; Giammanco, S.; Pecora, E.; Privitera, E.; Reitano, D.

    2006-12-01

    Continuous soil radon monitoring was carried out near the Southeast Crater (SEC) of Mt. Etna during the 10-day July 2006 Strombolian-effusive eruption. This signal was compared with simultaneously acquired volcanic tremor and thermal radiance data. The onset of explosive activity and a lava fountaining episode were preceded by some hours with increases in radon soil emission by 4-5 orders of magnitude, which we interpret as precursors. Minor changes in eruptive behavior did not produce significant variations in the monitored parameters. The remarkably high radon concentrations we observed are unprecedented in the literature. We interpret peaks in radon activity as due primarily to microfracturing of uranium-bearing rock. These observations suggest that radon measurements in the summit area of Etna are strongly controlled by the state of stress within the volcano and demonstrate the usefulness of radon data acquisition before and during eruptions.

  4. Influence of petrophysical parameters on eruption dynamics: a rheological study of the erupted products of Mt. Yasur, Vanuatu

    NASA Astrophysics Data System (ADS)

    Hanson, J. B.; Kremers, S. B.; Lavallee, Y.; Hess, K.; Dingwell, D. B.

    2011-12-01

    Mt. Yasur (Tanna, Vanuatu) is a small scoria cone (360 m high) and one of the most persistently active volcanoes worldwide. During the last ~10.000 years, Mt.Yasur mostly produced strong strombolian to vulcanian eruptions intercalated by sub-plinian eruptions every ca. 40 years. During a 6-week field campaign in August-September 2008, we installed four seismic and four infrasound arrays on site to record seismic and acoustic signals. Two Doppler-Radars measured the exit velocities of the erupted material, and a thermal camera was used to determine the temperature at the vent mouth. At the time of the fieldwork, three active craters showed very different styles of activity. Crater A, the most active vent, had an eruption recurrence of under a minute. Crater B showed very irregular ash-venting, while crater C was producing the strongest eruptions every 10 minutes. We sampled the eruptive products of craters A and C for further analysis in the lab. In total, three bombs were collected in order to investigate the chemical, physical, rheological and textural variations in the erupted products from the different craters. The collected basaltic-andesite scoria bombs exhibit a relatively constant whole rock major element geochemistry (~56 wt.% SiO2); correspondingly, the remelted whole rock viscosity, investigated via a combination of concentric cylinder rheometry and micropenetration, remains similar. Petrographic texture and structure analyses reveal a large variation in porosity (~30 - 78 %) and microlite content. Observation of aphyric zones grading abruptly or incrementally (on mm to cm scales) to nearly entirely crystalline zones suggest the occurrence of mingling and mixing of magma batches with different crystallization histories. The microlites are mostly anhydral, showing and needle-like growth pattern, with signs of kinetic growth disequilibrium similar to spherulites. Interstitial glass chemistry from electron microprobe analysis shows a range of glass

  5. Mt. Etna Eruption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1: Vis/NIR Image CloseupFigure 2: Difference Image

    October 2002 Mt. Etna, a volcano on the island of Sicily, erupted on October 26, 2002. Preliminary analysis of data taken by the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite on October 28 shows the instrument can provide an excellent means to study the evolution and structure of the sulfur dioxide (SO2) plume emitted from volcanoes. These data also demonstrate that AIRS can be used to obtain the total mass of SO2 injected into the atmosphere during a volcanic event, information that may help us to better understand these dangerous natural occurrences in the future.

    This image was made from a sensor on the AIRS instrument that is sensitive to the visible and near-infrared portions of the spectrum. The visible/near infrared data show the smoke plume from Mt. Etna. The view is of Europe and the central Mediterranean with Italy in the center. Since the visible/near infrared sensor on AIRS is sensitive to wavelengths that are different than the human eye, vegetated regions appear red (compare the red color of Europe with the tan desert of North Africa in the lower left). Figure 1 is a closer view of Sicily and shows a long, brownish smoke plume extending across the Mediterranean to Africa. This is consistent with the enhanced feature in the difference image in Figure 2 and helps validate the information inferred from that image.

    Figure 2 clearly shows the SO2 plume. This image was created by comparing data taken at two different frequencies, or channels, and creating one image that highlights the differences between these two channels. Both channels are sensitive to water vapor, but one of the channels is also sensitive to SO2. By subtracting out the common water vapor signal in both channels, the SO2 feature remains and shows up as an enhancement in the difference image.

    The

  6. Timescales of Human Interest in the Geological Records of Rhyolite Eruptions

    NASA Astrophysics Data System (ADS)

    Wilson, C. J. N.; Barker, S. J.; Myers, M.; Swallow, E. J.; Wallace, P. J.

    2015-12-01

    Prehistoric eruptions are generally treated as discrete events, separated from preceding and following events by periods defined by 14C or radiometric dating as centuries or longer. Modern events such as Monserrat (1995-?) or Mount St. Helens (1980-86; 2004-2008) blur this distinction with 'eruption episodes' versus 'separate eruptions' becoming a semantic issue. For rhyolite eruptions, where historic events are scarce, discerning episodicity within, or close spacing between, eruptions becomes important. Time gaps of a few decades or less are challenging to recognise and quantify in eruption products, but important in terms of modelling future events and considering the consequent hazards, economic impacts and associated societal responses. We here consider the geological record for the timing of prehistoric rhyolite eruptions over a range of sizes. In some, such as the Bishop Tuff, there is no evidence in the eruptive stratigraphy to suggest any significant hiatus in activity, and an overall timing of days for the main activity has been inferred. In contrast, evidence from other deposits indicates a prolongation of geologically distinct eruptions, such as the Oruanui (over several months) and Huckleberry Ridge Tuff (over likely over a few decades). Such evidence is in the form of syn-eruptive erosion and reworking, or breaks long enough for successive units to have contrasting welding histories but for the earlier units to still be hot and fumarolically active when the later ones were emplaced. Some eruptions in the young record from Taupo volcano were sourced from widely separated vents, yet have only subtle evidence for time breaks between them, suggestive of years to 1-2 decades. The youngest event at Taupo consisted of the catastrophic 232±5 CE explosive activity (eruption Y), which was followed by a break of 10±5 years before effusive activity (eruption Z) occurred under the re-formed Lake Taupo. The lengths of time breaks within and between rhyolite

  7. Transitions between explosive and effusive phases during the cataclysmic 2010 eruption of Merapi volcano, Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Preece, Katie; Gertisser, Ralf; Barclay, Jenni; Charbonnier, Sylvain J.; Komorowski, Jean-Christophe; Herd, Richard A.

    2016-08-01

    Transitions between explosive and effusive activity are commonly observed during dome-forming eruptions and may be linked to factors such as magma influx, ascent rate and degassing. However, the interplay between these factors is complex and the resulting eruptive behaviour often unpredictable. This paper focuses on the driving forces behind the explosive and effusive activity during the well-documented 2010 eruption of Merapi, the volcano's largest eruption since 1872. Time-controlled samples were collected from the 2010 deposits, linked to eruption stage and style of activity. These include scoria and pumice from the initial explosions, dense and scoriaceous dome samples formed via effusive activity, as well as scoria and pumice samples deposited during subplinian column collapse. Quantitative textural analysis of groundmass feldspar microlites, including measurements of areal number density, mean microlite size, crystal aspect ratio, groundmass crystallinity and crystal size distribution analysis, reveal that shallow pre- and syn-eruptive magmatic processes acted to govern the changing behaviour during the eruption. High-An (up to ˜80 mol% An) microlites from early erupted samples reveal that the eruption was likely preceded by an influx of hotter or more mafic magma. Transitions between explosive and effusive activity in 2010 were driven primarily by the dynamics of magma ascent in the conduit, with degassing and crystallisation acting via feedback mechanisms, resulting in cycles of effusive and explosive activity. Explosivity during the 2010 eruption was enhanced by the presence of a `plug' of cooled magma within the shallow magma plumbing system, which acted to hinder degassing, leading to overpressure prior to initial explosive activity.

  8. Initial Analysis of Inner Crater Eruptive Deposits and Modeling of the 2005 Eruption of Ilamatepec (Santa Ana) Volcano, El Salvador

    NASA Astrophysics Data System (ADS)

    Martinez-Hackert, B.; Bajo, J. V.; Escobar, D.; Gutierrez, E.

    2011-12-01

    The October 1st, 2005 eruption of Ilamatepec Volcano, also known as Santa Ana Volcano in El Salvador, Central America, was a relatively small phreatic possibly phreatomagmatic eruption that generated an approximately 10km high ash column, with a volume of 1.5 million cubic meters. It generated small pyroclastic density currents, and shortly after the eruption a hot lahar. All of these volcanic products present grat danger to the surrounding population and the surrounding fertile lands growing coffe and sugar cane, the major export products. To better understand the eruptive behavior of this active composite volcano, older deposits need to be studied. An initial analysis of the inner crater eruptive deposits was undertaken in 2011. The many layers that can be seen within the crater suggest that Santa Ana volcano alternates its eruptions from phreatic to phreatomagmatic to magmatic, back to phreatomagmatic to phreatic with a period of rest in between. The last magmatic eruption of the Santa Ana Volcano took place in 1904. There are some historical records of it, and the scoracious materials and lava flows can still be well traced on the flanks and the crater of Ilamatepec, while the 2005 eruption has been eroded away in most areas of the flanks. Observations and data collected in 2005 and 2011 indicate that pyroclastic density currents went not only to the Southeastern flanks of the volcano, but also towards the Northwestern flanks, an area behind the highest rim of the volcano. Deposits up to 0.5 m were found in 2011, after significant erosion already had taken place. We present here the partial stratigraphic column taken within the inner crater walls that indicate alternating eruption styles from eruptions well pre-1904, with radiocarbon dating pending. Additionally, we show the results of the modeling of pyroclastic deposits, and lahars using Titan2D on DEMs extracted from the only topographic map (pre-1980) which has a 10 m resolution of the volcano, and a DEM

  9. Inflate, Pause, Erupt, Recharge: the 2008 Alu eruption in the Erta ‘Ale volcanic system (Ethiopia)

    NASA Astrophysics Data System (ADS)

    Pagli, C.; Wright, T. J.; Ebinger, C. J.; Barnie, T. D.; Ayele, A.

    2009-12-01

    The Alu volcano is located within the Erta ‘Ale volcanic system in northern Afar (Ethiopia), about 30 km to the north of Erta ‘Ale volcano whose summit caldera hosts a persistent lava lake. On 3rd November 2008 a fissure eruption started east of Alu volcano. An unprecedented InSAR dataset, seismic records and other space satellite imagery allow us to study the temporal and spatial evolution of magma preceding, during and after the eruption. We use InSAR images from five tracks of the Envisat satellite both in descending ad ascending orbits. Small pre-eruptive inflation 3 cm/month started at Alu in July but had ceased by September 10. There was no deformation for around a month before the eruption began on November 3, 2008 at 11:10 GMT. During the eruption over 1 m of subsidence was observed at two distinct locations: at Alu and a volcanic ridge 3 km south of Alu. The co-eruptive subsidence continued for around 16 days at Alu, before deflation reversed into inflation. A swarm of earthquakes, some with magnitude (ml) > 4, occurred along the border fault escarpment, ~ 40 km west of Alu, at 22:00 GMT on November 2, and within ~4 hours a seismic activity started around Alu, leading to the eruption. The deformation was modelled with a Mogi source under Alu and a Sill under the ridge, undergoing different undergoing different volume changes from July 2008 to June 2009. In order to find the best-fit model parameters, first we modelled few selected co-eruptive interferograms with a non-linear inversion. Then, keeping fixed the model geometries we inverted a total of ~40 interferograms for the time-dependent volume change of the Mogi source and the opening of the sill, using a least-squares inversion. Results indicate that a small magma volume was intruded into Alu July-September but a time lag of ~ 1 month occurred between intrusion and eruption. Martin et al. (2008) used petrological evidence to suggest that fresh magma intruded into a magma chamber can cause volatile

  10. Rootless eruption of a mandibular permanent canine.

    PubMed

    Shapira, Yehoshua; Kuftinec, Mladen M

    2011-04-01

    The purpose of this article was to describe the rootless eruption of a mandibular permanent canine in a 10-year-old boy; his mandible had been fractured in a car accident. The fracture was at the region of the developing canine, resulting in arrested root formation and causing abnormal, rootless eruption. Current theories on tooth eruption and the important role of the dental follicle in the process of eruption are discussed. PMID:21457868

  11. Sequence of the 1895 eruption of the Zao volcano, Tohoku Japan

    NASA Astrophysics Data System (ADS)

    Miura, Kotaro; Ban, Masao; Ohba, Tsukasa; Fujinawa, Akihiko

    2012-12-01

    The most recent major eruption event of the Zao volcano comprised a series of phreatic eruption episodes on 15 and 19 February, 22 August, and 27-28 September 1895, with several precursory vulcanian eruptions during February-July 1894. All were generated at the Okama crater lake located inside the Umanose caldera. The eruption products consist mainly of hydrothermally altered ash with altered blocks, except for ash from 1984. The eruption deposits of 1895 are divided lithologically into six layers (1-6). Comparison of the document with the lithofacies of deposits shows that layers 1, 2, 3-4, and 5-6 were correlated respectively with eruption episodes of 15 February (episode 1), 19 February (episode 2), 22 August (episode3), and 27-28 September (episode 4). During these four episodes, ca. 0.5%, 0.5%, 1.5%, and 98% of the total mass of the products had been discharged. Based on lithologic, stratigraphic, granulometric, and component analyses and on distributional features for these layers, the following depositional mechanisms were inferred. Layers 1, 3, and 4 were formed mainly from their related small pyroclastic density currents, whereas layer 2 resulted mainly from a small pyroclastic fall. In contrast, layers 5 and 6 are larger-scale near-vent pyroclastic fall deposits from ash clouds and eruption clouds, which might have included some juvenile fragments. The three early episodes in 1985 led to the climactic episode of 27-28 September. Furthermore, the andesitic magma chamber at < 3 kb depth, which caused the 1894 vulcanian eruptions, became a hydrothermal alteration source for the 1895 erupted materials. The chamber was re-activated before 1895 eruption by injection of basaltic magmas from greater depth. The injection reached maximum at the climactic event. The inferred course of that series of eruption episodes provides useful information to predict future volcanic phreatic-type eruptions at this volcano.

  12. Sorafenib induced eruptive melanocytic lesions.

    PubMed

    Uhlenhake, Elizabeth E; Watson, Alice C; Aronson, Peter

    2013-05-01

    Sorafenib is a multikinase inhibitor FDA-approved for the treatment of advanced renal cell and hepatocellular carcinoma. Dermatologic side effects include hand-foot skin reaction, facial and scalp erythema and desquamation, splinter subungual hemorrhages, alopecia, pruritus, xerosis, keratoacanthomas, and squamous cell carcinomas. We report sudden eruption of melanocytic nevi diffusely in a patient receiving sorafenib. PMID:24011281

  13. 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.

  14. Eruption conditions of spatter deposits

    NASA Astrophysics Data System (ADS)

    Rader, Erika; Geist, Dennis

    2015-10-01

    Spatter is an eruptive product that forms within a narrow range of thermal conditions: it must be hot enough to deform and agglutinate, but not so hot that clasts completely re-fuse and remobilize as clastogenic lava. This narrow thermal window of spatter-forming conditions allows for quantitative prediction of cooling rates and accumulation rates. Cooling and accumulation rates then provide information that enables estimates of eruption parameters for inaccessible and prehistoric deposits. High-temperature experiments conducted on basaltic scoria from Devil's Garden, Oregon have revealed the eruption temperature was ~ 1130 °C. The strength welds formed between experimental clasts is shown to depend on cooling rate. Natural samples are compared to the experimental samples by measuring tensile strength and welded area between clasts. The weld strength in natural deposits yields estimates of cooling rates that range between 2.5 °C and 48 °C/min, with the majority of the samples grouping between 7 °C and 14 °C/min. Thermal models based on these cooling rates yield spatter accumulation rates of 0.5-1.8 m/h in the Devil's Garden spatter deposits. We provide a general model for cooling and accumulation rates for spatter cones, ramparts, and hornitos, which allow estimation of the factors that control basaltic eruptive products.

  15. Consistent decrease in North Atlantic Tropical Cyclone frequency following major volcanic eruptions in the last three centuries

    NASA Astrophysics Data System (ADS)

    Guevara-Murua, A.; Hendy, E. J.; Rust, A. C.; Cashman, K. V.

    2015-11-01

    Injection of sulphate aerosols into the stratosphere following major volcanic eruptions alters global climate through the absorption and scattering of solar radiation. One proposed consequence is a decrease in North Atlantic Tropical Cyclone (TC) activity, as was observed following the El Chichón (1982) and Mount Pinatubo (1991) eruptions. We test this relationship using documentary and proxy reconstructions of major volcanic eruptions and TC frequency in the North Atlantic basin over the last three centuries. We find a consistent reduction in the number of TCs formed during the 3 years following major eruptions compared to the preceding 3 years, including after eruptions located at northern high latitudes. Our findings suggest that low-latitude eruptions reduce Atlantic TC frequency by decreasing local sea surface temperatures, whereas the mechanisms for the decrease in TC frequency following high-latitude eruptions are less clear and attribution is hampered by poor identification of these events.

  16. Preliminary impact assessment of effusive eruptions at Etna volcano

    NASA Astrophysics Data System (ADS)

    Cappello, Annalisa; Michaud-Dubuy, Audrey; Branca, Stefano; De Beni, Emanuela; Del Negro, Ciro

    2016-04-01

    Lava flows are a recurring and widespread form of volcanic activity that threaten people and property around the world. The growing demographic congestion around volcanic structures increases the potential risks and costs that lava flows represent, and leads to a pressing need for faster and more accurate assessment of lava flow impact. To fully evaluate potential effects and losses that an effusive eruption may cause to society, property and environment, it is necessary to consider the hazard, the distribution of the exposed elements at stake and the associated vulnerability. Lava flow hazard assessment is at an advanced state, whereas comprehensive vulnerability assessment is lacking. Cataloguing and analyzing volcanic impacts provide insight on likely societal and physical vulnerabilities during future eruptions. Here we quantify the lava flow impact of two past main effusive eruptions of Etna volcano: the 1669, which is the biggest and destructive flank eruption to have occurred on Etna in historical time, and the 1981, lasting only 6 days, but characterized by an intense eruptive dynamics. Different elements at stake are considered, including population, hospitals, critical facilities, buildings of historic value, industrial infrastructures, gas and electricity networks, railways, roads, footways and finally land use. All these elements were combined with the 1669 and 1981 lava flow fields to quantify the social damage and economic loss.

  17. Assessment of the atmospheric impact of volcanic eruptions

    NASA Technical Reports Server (NTRS)

    Sigurdsson, H.

    1988-01-01

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

  18. The June 2014 eruption at Piton de la Fournaise: Robust methods developed for monitoring challenging eruptive processes

    NASA Astrophysics Data System (ADS)

    Villeneuve, N.; Ferrazzini, V.; Di Muro, A.; Peltier, A.; Beauducel, F.; Roult, G. C.; Lecocq, T.; Brenguier, F.; Vlastelic, I.; Gurioli, L.; Guyard, S.; Catry, T.; Froger, J. L.; Coppola, D.; Harris, A. J. L.; Favalli, M.; Aiuppa, A.; Liuzzo, M.; Giudice, G.; Boissier, P.; Brunet, C.; Catherine, P.; Fontaine, F. J.; Henriette, L.; Lauret, F.; Riviere, A.; Kowalski, P.

    2014-12-01

    After almost 3.5 years of quiescence, Piton de la Fournaise (PdF) produced a small summit eruption on 20 June 2014 at 21:35 (GMT). The eruption lasted 20 hours and was preceded by: i) onset of deep eccentric seismicity (15-20 km bsl; 9 km NW of the volcano summit) in March and April 2014; ii) enhanced CO2 soil flux along the NW rift zone; iii) increase in the number and energy of shallow (<1.5 km asl) VT events. The increase in VT events occurred on 9 June. Their signature, and shallow location, was not characteristic of an eruptive crisis. However, at 20:06 on 20/06 their character changed. This was 74 minutes before the onset of tremor. Deformations then began at 20:20. Since 2007, PdF has emitted small magma volumes (<3 Mm3) in events preceded by weak and short precursory phases. To respond to this challenging activity style, new monitoring methods were deployed at OVPF. While the JERK and MSNoise methods were developed for processing of seismic data, borehole tiltmeters and permanent monitoring of summit gas emissions, plus CO2 soil flux, were used to track precursory activity. JERK, based on an analysis of the acceleration slope of a broad-band seismometer data, allowed advanced notice of the new eruption by 50 minutes. MSNoise, based on seismic velocity determination, showed a significant decrease 7 days before the eruption. These signals were coupled with change in summit fumarole composition. Remote sensing allowed the following syn-eruptive observations: - INSAR confirmed measurements made by the OVPF geodetic network, showing that deformation was localized around the eruptive fissures; - A SPOT5 image acquired at 05:41 on 21/06 allowed definition of the flow field area (194 500 m2); - A MODIS image acquired at 06:35 on 21/06 gave a lava discharge rate of 6.9±2.8 m3 s-1, giving an erupted volume of 0.3 and 0.4 Mm3. - This rate was used with the DOWNFLOW and FLOWGO models, calibrated with the textural data from Piton's 2010 lava, to run lava flow

  19. Surface Flux Emergence and Coronal Eruption

    NASA Astrophysics Data System (ADS)

    Fang, Fang

    2016-05-01

    Among various active regions, delta-sunspots of aggregated spots of opposite polarities, are of particular interest due to their high productivity in energetic and recurrent eruptive events, such as X-class flares and homologous eruptions. We here study the formation of such complex magnetic structures by numerical simulations of magnetic flux emergence from the convection zone into the corona in an active-region scale domain. In our simulation, two pairs of bipolar sunspots form on the surface, originating from two buoyant segments of a single subsurface twisted flux rope. Expansion and rotation of the emerging fields in the two bipoles drive the two opposite polarities into each other with apparent rotating motion, producing a compact delta-sunspot with a sharp polarity inversion line (PIL). The formation of the delta-sunspot in such a realistic-scale domain produces emerging patterns similar to those formed in observations, e.g. the inverted polarity against Hale’s law, the curvilinear motion of the spot, strong transverse field with highly sheared magnetic and velocity fields at the PIL. Strong current builds up at the PIL, giving rise to reconnection, which produces a complex coronal magnetic connectivity with non-potential fields in the delta-spot overlaid by more relaxed fields connecting the two polarities at the two ends.

  20. The First Historic Eruption of Nabro, Eritrea: Insights from Thermal and UV Satellite Data

    NASA Astrophysics Data System (ADS)

    Sealing, C. R.; Carn, S. A.; Harris, A. J. L.

    2015-12-01

    In June 2011, the first recorded eruption of Nabro volcano, took place at the border of Eritrea and Ethiopia. This eruption was the largest in what could be considered an ongoing sequence of eruptions in the Afar-Red Sea region since 2005. It halted air travel in northern Africa, contaminated food and water sources, and displaced thousands from their homes. Geographic isolation, previous quiescence, and regional civil unrest meant that this volcano was effectively unmonitored at the time of eruption, and opportunities for field study were limited. The purpose of this study is to explore the quantity of erupted products and the timing and mechanisms of their emplacement using predominantly free, publicly available satellite data. We use MODIS and OMI data to examine rates of lava effusion and SO2 emission, and quantify the amount of erupted products. We also examine published images from other satellites, such as ALI and SEVIRI in order to understand the temporal evolution of the eruption. Synthesizing these data, we then attempt to infer the mechanisms through which the eruption progressed. Examination of satellite data reveals a bimodal eruption, beginning with explosive activity marked by high SO2 emission totalling 1824 - 2299 KT, and extensive ash fall of 270 - 440 km2. This was followed by a period of rapid effusion, producing a ~17 km long lava flow, and a volume of ~22.1 x 106 m3. Mass balance between the SO2 and lava flows reveals no sulfur 'excess', suggesting that nearly all of the degassed magma was extruded. This eruption of Nabro continued for nearly 6 weeks, and may be considered the second largest historic eruption in Africa. This type of work highlights the effectiveness and importance of accessible satellite remote sensing data for the study of active volcanoes, particularly those in remote regions that may be otherwise inaccessible.

  1. Descent of tremor source locations before the 2014 phreatic eruption of Ontake volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ogiso, Masashi; Matsubayashi, Hirotoshi; Yamamoto, Tetsuya

    2015-12-01

    On 27 September 2014, Ontake volcano, in central Japan, suddenly erupted without precursory activity. We estimated and tracked the source locations of volcanic tremor associated with the eruption at high temporal resolution, using a method based on the spatial distribution of tremor amplitudes. Although the tremor source locations were not well constrained in depth, their epicenters were well located beneath the erupted crater and the summit. Tremor sources were seen to descend approximately 2 km over a period of several minutes prior to the beginning of the eruption. Detailed analysis of the time series of tremor amplitudes suggests that this descent is a robust feature. Our finding may be an important constraint for modeling the 2014 eruption of Ontake volcano as well as for monitoring activities on this and other volcanoes.

  2. The Tala Tuff, La Primavera caldera Mexico. Pre-eruptive conditions and magma processes before eruption

    NASA Astrophysics Data System (ADS)

    Sosa-Ceballos, G.

    2015-12-01

    La Primavera caldera, Jalisco Mexico, is a Pleistocenic volcanic structure formed by dome complexes and multiple pyroclastic flows and fall deposits. It is located at the intersection of the Chapala, Colima, and Tepic grabens in western Mexico. The first volcanic activity associated to La Primavera started ~0.1 Ma with the emission of pre-caldera lavas. The caldera collapse occurred 95 ka and is associated to the eruption of ~20 km3of pumice flows known as the Tala tuff (Mahood 1980). The border of the caldera was replaced by a series of domes dated in 75-30 ky, which partially filled the inner depression of the caldera with pyroclastic flows and falls. For more than a decade the Federal Commission of Electricity in Mexico (CFE) has prospected and evaluated the geothermal potential of the Cerritos Colorados project at La Primavera caldera. In order to better understand the plumbing system that tapped the Tala tuff and to investigate its relation with the potential geothermal field at La Primavera we performed a series of hydrothermal experiments and studied melt inclusions hosted in quartz phenocrysts by Fourier Infra red stectroscopy (FTIR). Although some post caldera products at La Primavera contain fayalite and quartz (suggesting QFM conditions) the Tala tuff does not contain fayalite and we ran experiments under NNO conditions. The absence of titanomagnetite does not allowed us to calculate pre-eruptive temperature. However, the stability of quartz and plagioclase, which are natural phases, suggest that temperature should be less than 750 °C at a pressure of 200 MPa. The analyses of H2O and CO2 dissolved in melt inclusions yielded concentrations of 2-5 wt.% and 50-100 ppm respectively. This data confirm that the pre-eruptive pressure of the Tala tuff is ~200 MPa and in addition to major elements compositions suggest that the Tala tuff is either, compositionally zoned or mixed with other magma just prior to eruption.

  3. Large X-class Flare Erupting on Jan. 27

    NASA Video Gallery

    On Jan. 27, 2012 a large X-class flare erupted from an active region near the solar west limb. Seen here is a time series of the flare captured by the X-ray telescope on Hinode. These images repres...

  4. Vulcanian explosions: precursory and eruptive signatures from a multiparameteric perspective

    NASA Astrophysics Data System (ADS)

    Gottsmann, J.; De Angelis, S.; Fournier, N.; Sacks, S. I.; Van Camp, M. J.; Linde, A. T.; Ripepe, M.

    2012-12-01

    Vulcanian explosions: precursory and eruptive signatures from a multiparameteric perspective Vulcanian eruptions form a continuum ranging from the weaker Strombolian-type to violent sub-Plinian activity. They are short-lived (tens of seconds to tens of minutes) events commonly associated with a Volcanic Eruption Index (VEI) of 2-3. Extrusion of viscous magma and the formation of a lava dome is often interspersed by short-lived vigorous (Vulcanian) explosions. The causes for and the timing of the transition from effusive to explosive activity during dome formation are poorly understood and forecasting this transition remains a challenge. Previous investigations have pointed towards pressure sources at shallow levels in volcanic conduits, which ultimately fuel Vulcanian explosions. Here, we describe and interpret a robust and unique multi-parameter data set documenting the subsurface processes associated with Vulcanian explosions at Soufriere Hills Volcano, Montserrat. We show that explosion priming can be driven by processes in the shallow or the deep magmatic system. The geophysical constraints on the eruption dynamics are consitent with the geological evidence of eruptive products. One geophysical signature is related exclusively to shallow dynamics including conduit destabilisation, syn-eruptive decompression and magma fragmentation, conduit emptying and expulsion of juvenile pumice. By contrast, another explosion was triggered by unprecedented sudden pressurisation of the entire plumbing system from depths of about 10 km resulting in the partial failure of the dome carapace, a violent cannon-like explosion, propagation of pressure waves and pronounced ballistic ejection of dome fragments. The timescale for explosion precursors is on the order of few minutes for both types of explosions, however, the precursory geophysical signatures are indicative of the nature of ensuing explosions. The short precursory phases characterise Vulcanian explosions as freak events

  5. The 2006 lava dome eruption of Merapi Volcano (Indonesia): Detailed analysis using MODIS TIR

    NASA Astrophysics Data System (ADS)

    Carr, Brett B.; Clarke, Amanda B.; Vanderkluysen, Loÿc

    2016-02-01

    Merapi is one of Indonesia's most active and dangerous volcanoes. Prior to the 2010 VEI 4 eruption, activity at Merapi during the 20th century was characterized by the growth and collapse of a series of lava domes. Periods of very slow growth were punctuated by short episodes of increased eruption rates characterized by dome collapse-generated pyroclastic density currents (PDCs). An eruptive event of this type occurred in May-June, 2006. For effusive eruptions such as this, detailed extrusion rate records are important for understanding the processes driving the eruption and the hazards presented by the eruption. We use thermal infrared (TIR) images from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on NASA's Aqua and Terra satellites to estimate extrusion rates at Merapi Volcano during the 2006 eruption using the method of Harris and Ripepe (2007). We compile a set of 75 nighttime MODIS images of the eruptive period to produce a detailed time series of thermal radiance and extrusion rate that reveal multiple phases of the 2006 eruption. These data closely correspond to the published ground-based observational record and improve observation density and detail during the eruption sequence. Furthermore, additional analysis of radiance values for thermal anomalies in Band 21 (λ = 3.959 μm) of MODIS images results in a new framework for detecting different styles of activity. We successfully discriminate among slow dome growth, rapid dome growth, and PDC-producing dome collapse. We also demonstrate a positive correlation between PDC frequency and extrusion rate, and provide evidence that extrusion rate can increase in response to external events such as dome collapses or tectonic earthquakes. This study represents a new method of documenting volcanic activity that can be applied to other similar volcanic systems.

  6. Some observations regarding the thermal flux from Earth's erupting volcanoes for the period 2000 to 2014

    NASA Astrophysics Data System (ADS)

    Wright, R.; Blackett, M.; Hill-Butler, C.

    2014-12-01

    This presentation will describe 15 years of MODIS observations of the thermal flux from Earth's sub-aerially erupting volcanoes. The MODVOLC algorithm has been providing data regarding volcanic eruptions on Earth to the volcanological community since the launch of Terra MODIS, via the internet, in near-real-time (http:modis.higp.hawaii.edu). During this time, eruptions at 102 volcanoes have been observed, including activity associated with mafic lava flows, lava lakes, vent-based explosive activity and felsic lava domes. This presentation will present an overview of how MODIS has documented every eruption to occur on Earth since 2000, and will describe some of the more interesting result that have been obtained from the analysis of this archive. The total amount of energy radiated into the atmosphere can be divided into two parts: a baseline level of emission which has increased gradually over this 15 period, superimposed on which are large "spikes" attributable to large, lava-flow-forming eruptions. The most intense eruption during this period of time was the 2004 eruption of Nyamuragira, in the Democratic Republic of Congo, whilst the largest magnitude event was the 2012-2013 eruption of Tolbachik, Russia. Spatio-temporal patterns in thermal output will be addressed. Time-series analysis of heat flux from these 102 volcanoes has revealed while some volcanoes exhibit statistically significant periodicity in the magnitude of their heat output, many do not.

  7. The magmatic and eruptive response of arc volcanoes to deglaciation: insights from southern Chile

    NASA Astrophysics Data System (ADS)

    Mather, T. A.; Rawson, H. L.; Smith, V.; Fontijn, K.; Lachowycz, S.; Pyle, D. M.; Naranjo, J. A.; Watt, S. F.

    2015-12-01

    In plate-tectonic settings where magmatism is driven by decompression melting there is convincing evidence that activity is modulated by changes in ice- or water-loading across glacial/interglacial cycles. In contrast, the response of subduction-related volcanoes, where the crust is typically thicker and mantle melting is dominated by flux melting, remains unclear. The large areas spanned by arcs, and the typical activity at subduction zone volcanoes present particular challenges when compiling regional eruption archives. Records of effusive eruptions from long-lived, arc stratovolcanoes are challenging to obtain, and date; while deposits from the explosive eruptions, which dominate arc records, are prone to erosion and reworking. Here we use a rare high-resolution post-glacial (<18 ka) eruption record from a large stratovolcano (Mocho-Choshuenco) in southern Chile to gain new insight into the magmatic response to removal of an ice load; variation in eruptive flux, eruption size and magma composition are observed and divided into three distinct phases based on style of activity and erupted composition. Phase 1, shortly after deglaciation, was dominated by large explosive eruptions of dacite and rhyolite. During Phase 2 (7.3 - 2.9 ka) eruption rates and eruptive fluxes were lower, and activity was dominated by moderate-scale basaltic-andesite eruptions. Since 2.4 ka (Phase 3) eruptive fluxes have been elevated, and dominated by explosive eruptions of more intermediate magmas. This time-varying behaviour reflects changes in crustal plumbing systems, and magma storage timescales. During glaciations, magmas stall and differentiate to form large, evolved crustal reservoirs. After the load is removed, much of this stored magma is erupted (Phase 1). Subsequently, less-differentiated melts infiltrate the shallow crust (Phase 2). Then, as storage timescales increase, volcanism returns to more evolved compositions (Phase 3). On short (<10 kyr) timescales these variations are

  8. The magmatic and eruptive response of arc volcanoes to deglaciation: insights from southern Chile

    NASA Astrophysics Data System (ADS)

    Rawson, Harriet; Mather, Tamsin A.; Pyle, David M.; Smith, Victoria C.; Fontijn, Karen; Lachowycz, Stefan; Naranjo, José A.; Watt, Sebastian F. L.

    2016-04-01

    Volcanism exerts a major influence on Earth's atmosphere and surface environments. Understanding feedbacks between climate and long-term changes in rates or styles of volcanism is important, but unresolved. For example, it has been proposed that a pulse of activity at once-glaciated volcanoes contributed to increasing atmospheric carbon dioxide accelerating early Holocene climate change. In plate-tectonic settings where magmatism is driven by decompression melting there is convincing evidence that activity is modulated by changes in ice- or water-loading across glacial/interglacial cycles. The response of subduction-related volcanoes, where the crust is typically thicker and mantle melting is dominated by flux melting, remains unclear. Since arc volcanoes account for 90% of subaerial eruptions, they are the most significant sources of volcanic gases and tephra directly to the atmosphere. Testing the response of arc volcanoes to deglaciation requires careful work to piece together eruption archives. Records of effusive eruptions from long-lived, arc stratovolcanoes are challenging to obtain and date; while deposits from the explosive eruptions, which dominate arc records, are prone to erosion and reworking. Our new high-resolution post-glacial (<18 ka) eruption record from a large stratovolcano in southern Chile (Mocho Choshuenco) provides new insight into the magmatic response following the removal of a regional ice load. We observe significant variations in eruptive flux, eruption size and magma composition across three distinct phases of post-glacial volcanic activity. Phase 1, shortly after deglaciation, was dominated by large explosive eruptions of dacite and rhyolite. During Phase 2 (7.3 - 2.9 ka) eruption rates and eruptive fluxes were lower, and activity was dominated by moderate-scale basaltic-andesite eruptions. For the past 2.4 kyr (Phase 3), eruptive fluxes have been elevated, and dominated by explosive eruptions of intermediate magmas. We propose that

  9. Multidisciplinary observations of the 2011 explosive eruption of Telica volcano, Nicaragua: Implications for the dynamics of low-explosivity ash eruptions

    NASA Astrophysics Data System (ADS)

    Geirsson, Halldor; Rodgers, Mel; LaFemina, Peter; Witter, Molly; Roman, Diana; Muñoz, Angelica; Tenorio, Virginia; Alvarez, Julio; Jacobo, Vladimir Conde; Nilsson, Daniel; Galle, Bo; Feineman, Maureen D.; Furman, Tanya; Morales, Allan

    2014-02-01

    We present multidisciplinary observations of the March-June 2011 VEI 2 eruptive episode of the basaltic-andesite Telica volcano, Nicaragua, which allow for a comprehensive study of the eruption mechanics of low-explosivity eruptions at persistently active volcanoes. The observations are from a dense network of seismic and GPS instrumentation augmented by visual observations of the eruptive episode, geochemical and petrologic analysis of eruptive products, plume SO2 measurements, and temperature measurements of fumaroles inside and outside the active vent. The 2011 eruptive episode was Telica's most explosive since 1999 and consisted of numerous vulcanian explosions, with maximum column heights of 1.5-2 km above the crater rim, depositing a low volume of dominantly hydrothermally altered ash. Based on observed variations in seismicity, temperature, and SO2 flux, the lack of deformation of the edifice, the non-juvenile origin of and predominance of accretionary lapilli in the ash, we propose that temporary sealing of the hydrothermal system between ~ 0.5 and 2 km depth, allowed pressure to build up prior to vulcanian explosions, making this a phreatic eruptive episode.

  10. Io Eclipse/Volcanic Eruption

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image was acquired while Io was in eclipse (in Jupiter's shadow) during Galileo's eighth orbit, and reveals several dynamic processes. The most intense features are red, while glows of lesser intensity are yellow or green, and very faint glows appear blue in this color-coded image. The small red or yellow spots mark the sites of high-temperature magma erupting onto the surface in lava flows or lava lakes.

    This image reveals a field of bright spots near Io's sub-Jupiter point (right-hand side of image). The sub-Jupiter hemisphere always faces Jupiter just as the Moon's nearside always faces Earth. There are extended diffuse glows on the equatorial limbs or edges of the planet (right and left sides). The glow on the left is over the active volcanic plume Prometheus, but whereas Prometheus appears to be 75 kilometers (46.6 miles) high in reflected light, here the diffuse glow extends about 800 kilometers (497 miles) from Io's limb. This extended glow indicates that gas or small particles reach much greater heights than the dense inner plume. The diffuse glow on the right side reaches a height of 400 kilometers (249 miles), and includes a prominence with a plume-like shape. However, no volcanic plume has been seen at this location in reflected light. This type of observation is revealing the relationships between Io's volcanism, atmosphere and exosphere.

    Taken on May 6, 1997, north is toward the top. The image was taken with the clear filter of the solid state imaging (CCD) system on NASA's Galileo spacecraft at a range of 1.8 million kilometers (1.1 million miles).

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and

  11. Influences on the variability of eruption sequences and style transitions in the Auckland Volcanic Field, New Zealand

    NASA Astrophysics Data System (ADS)

    Kereszturi, Gábor; Németh, Károly; Cronin, Shane J.; Procter, Jonathan; Agustín-Flores, Javier

    2014-10-01

    Monogenetic basaltic volcanism is characterised by a complex array of eruptive behaviours, reflecting spatial and temporal variability of the magmatic properties (e.g. composition, eruptive volume, magma flux) as well as environmental factors at the vent site (e.g. availability of water, country rock geology, faulting). These combine to produce changes in eruption style over brief periods (minutes to days) in many eruption episodes. Monogenetic eruptions in some volcanic fields often start with a phreatomagmatic vent-opening phase that later transforms into "dry" magmatic explosive or effusive activity, with a strong variation in the duration and importance of this first phase. Such an eruption sequence pattern occurred in 83% of the known eruption in the 0.25 My-old Auckland Volcanic Field (AVF), New Zealand. In this investigation, the eruptive volumes were compared with the sequences of eruption styles preserved in the pyroclastic record at each volcano of the AVF, as well as environmental influencing factors, such as distribution and thickness of water-saturated semi- to unconsolidated sediments, topographic position, distances from known fault lines. The AVF showed that there is no correlation between ejecta ring volumes and environmental influencing factors that is valid for the entire AVF. In contrary, using a set of comparisons of single volcanoes with well-known and documented sequences, resultant eruption sequences could be explained by predominant patterns of the environment in which these volcanoes were erupted. Based on the spatial variability of these environmental factors, a first-order susceptibility hazard map was constructed for the AVF that forecasts areas of largest likelihood for phreatomagmatic eruptions by overlaying topographical and shallow geological information. Combining detailed phase-by-phase breakdowns of eruptive volumes and the event sequences of the AVF, along with the new susceptibility map, more realistic eruption scenarios can be

  12. Unusual Volcanic Products From the 2008 Eruption at Volcan Llaima, Chile

    NASA Astrophysics Data System (ADS)

    Sweeney, D. C.; Hughes, M.; Calder, E. S.; Cortes, J.; Valentine, G.; Whelley, P.; Lara, L.

    2009-05-01

    Volcan Llaima, a snow-covered basaltic andesite stratocone in southern Chile (38 41' S, 71 44' W, 3179 m a.s.l.), erupted on 1 January 2008 with a fire fountain display lasting 14 hours. Elevated activity continues to date with mild to moderate strombolian activity occurring from two nested scoria cones in the summit crater and with occasional lava flows from crater overflow. The eruption displayed contrasting styles of activity emanating from different parts of the edifice that may provide some unique insight into the upper level plumbing system. Furthermore, the activity has provided an excellent chance to study the transition of a normally passive degassing system into a violent eruptive cycle. A field study of the eruptive products from this eruption was completed in January 2009, where sampling was carried out from the tephra fall, lava flows, lahar deposits and even small pyroclastic flow deposits. The scoria samples collected suggest a mixture of two magmas involved in the initial violent, fire fountaining activity from the summit. Additionally, they exhibit a variety of unusual textures, including rapidly-quenched, dense lava 'balls' - generated at the front of the lava flows traveling through ice, as well as cauliflower-textured tephra from explosive eruptions though ice. This presentation comprises our observations and preliminary interpretations concerning the processes that occurred during this unique eruption.

  13. Direct video and hydrophone observations of submarine explosive eruptions at NW Rota-1 volcano, Mariana arc

    NASA Astrophysics Data System (ADS)

    Chadwick, W. W.; Cashman, K. V.; Embley, R. W.; Matsumoto, H.; Dziak, R. P.; de Ronde, C. E. J.; Lau, T. K.; Deardorff, N. D.; Merle, S. G.

    2008-08-01

    Extraordinary video and hydrophone observations of a submarine explosive eruption were made with a remotely operated vehicle in April 2006 at a depth of 550-560 m on NW Rota-1 volcano in the Mariana arc. The observed eruption evolved from effusive to explosive, while the eruption rate increased from near zero to 10-100 m3/h. During the peak in activity, cyclic explosive bursts 2-6 min long were separated by shorter non-eruptive pauses lasting 10-100 s. The size of the ejecta increased with the vigor of the explosions. A portable hydrophone deployed near the vent recorded sounds correlated with the explosive bursts; the highest amplitudes were ˜50 dB higher than ambient noise at frequencies between 10 and 50 Hz. The acoustic data allow us to quantify the durations, amplitudes, and evolution of the eruptive events over time. The low eruption rate, high gas/lava ratio, and rhythmic eruptive behavior at NW Rota-1 are most consistent with a Strombolian eruptive style. We interpret that the eruption was primarily driven by the venting of magmatic gases, which was also the primary source of the sound recorded during the explosive bursts. The rhythmic nature of the bursts can be explained by partial gas segregation in the conduit and upward migration in a transitional regime between bubbly flow and fully developed slug flow. The strongest explosive bursts were accompanied by flashes of red glow and oscillating eruption plumes in the vent, apparently caused by magma-seawater interaction and rapid steam formation and condensation. This is the first time submarine explosive eruptions have been witnessed with simultaneous near-field acoustic recordings.

  14. Volcanic eruption detection with TOMS

    NASA Technical Reports Server (NTRS)

    Krueger, Arlin J.

    1987-01-01

    The Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) is designed for mapping of the atmospheric ozone distribution. Absorption by sulfur dioxide at the same ultraviolet spectral wavelengths makes it possible to observe and resolve the size of volcanic clouds. The sulfur dioxide absorption is discriminated from ozone and water clouds in the data processing by their spectral signatures. Thus, the sulfur dioxide can serve as a tracer which appears in volcanic eruption clouds because it is not present in other clouds. The detection limit with TOMS is close to the theoretical limit due to telemetry signal quantization of 1000 metric tons (5-sigma threshold) within the instrument field of view (50 by 50 km near the nadir). Requirements concerning the use of TOMS in detection of eruptions, geochemical cycles, and volcanic climatic effects are discussed.

  15. Eruption column modeling of supervolcanoes

    NASA Astrophysics Data System (ADS)

    Dobran, F.

    2010-12-01

    Eruption columns consists of multiphase mixtures of gases and particulate matter in thermodynamic non-equilibrium, and tracking the multitude of interfaces associated with the liquid, solid, and plastic bodies of a wide spectrum of sizes is not practical. The current modeling practice is to use different averaging procedures by employing single-phase continuum models or those from the kinetic theory, together with various conditions that specify the microphysical processes of mixtures. But these models are inadequate to model the eruption columns of supervolcanoes, where the plumes reach the stratosphere and phase change processes contribute to the columns’ dispersion properties on the regional and global scales. A more effective multiphase flow modeling procedure is presented and its computer implementation is discussed.

  16. Solar Eruptions and Energetic Particles

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Natchimuthukonar; Mewaldt, Richard; Torsti, Jarmo

    Coronal mass ejections (CMEs) are the most energetic events in the heliosphere. During solar cycle 23, the close connection between CMEs and solar energetic particles (SEPs) was studied in much greater detail than was previously possible, including effects on space weather. This book reviews extensive observations of solar eruptions and SEPs from orbiting and ground-based systems. From SOHO and ACE to RHESSI and TRACE, we now have measurements of unprecedented sensitivity by which to test assumptions and refine models. Discussion and analysis of: • Coronal mass ejections and energetic particles over one solar cycle • Implications of solar eruptions for space weather and human space exploration • The elemental, isotopic, and ionic charge state composition of accelerated particles • Complex interconnections among CMEs, flares, shocks, and energetic particles will make this book an indispensable resource for scientists working on the Sun-Earth connection, including space physicists, magnetospheric physicists, atmospheric physicists, astrophysicists, and aeronomists.

  17. Supercomputer modeling of volcanic eruption dynamics

    SciTech Connect

    Kieffer, S.W.; Valentine, G.A.; Woo, Mahn-Ling

    1995-06-01

    Our specific goals are to: (1) provide a set of models based on well-defined assumptions about initial and boundary conditions to constrain interpretations of observations of active volcanic eruptions--including movies of flow front velocities, satellite observations of temperature in plumes vs. time, and still photographs of the dimensions of erupting plumes and flows on Earth and other planets; (2) to examine the influence of subsurface conditions on exit plane conditions and plume characteristics, and to compare the models of subsurface fluid flow with seismic constraints where possible; (3) to relate equations-of-state for magma-gas mixtures to flow dynamics; (4) to examine, in some detail, the interaction of the flowing fluid with the conduit walls and ground topography through boundary layer theory so that field observations of erosion and deposition can be related to fluid processes; and (5) to test the applicability of existing two-phase flow codes for problems related to the generation of volcanic long-period seismic signals; (6) to extend our understanding and simulation capability to problems associated with emplacement of fragmental ejecta from large meteorite impacts.

  18. Petrological analysis of the pre-eruptive magmatic process prior to the 2006 explosive eruptions at Tungurahua volcano (Ecuador)

    NASA Astrophysics Data System (ADS)

    Samaniego, Pablo; Le Pennec, Jean-Luc; Robin, Claude; Hidalgo, Silvana

    2011-01-01

    Understanding the processes at the origin of explosive events is crucial for volcanic hazard mitigation, especially during long-lasting eruptions at andesitic volcanoes. This work exposes the case of Tungurahua volcano, whose unrest occurred in 1999. Since this date, the eruptive activity was characterized by low-to moderate explosiveness, including phases with stronger canon-like explosions and regional ash fallout. However, in 2006, a sudden increase of the explosiveness led to pyroclastic flow-forming eruptions on July 14th (VEI 2) and August 16-17th (VEI 3). All magmas emitted from 1999 to 2005, as well as the samples from the 2006 eruptions, have homogeneous bulk-rock andesitic compositions (58-59 wt.% SiO 2), and contain the same mineral assemblage consisting of pl + cpx + opx + mag ± ol. However, during the August 16-17th event, the erupted tephra comprise two types of magmas: a dominant, brown andesitic scoria; and scarce, light-grey pumice representing a subordinate, silica-rich juvenile component. For the andesitic magma, thermobarometric data point to magmatic temperatures ranging from 950 to 1015 °C and pressures in the range of 200 to 250 MPa, which corresponds to 7.5-9.5 km below the summit. Disequilibrium textures in plagioclase and pyroxene phenocrysts, particularly thin overgrowth rims, indicate the recharge of this magma body by mafic magma. Between 1999 and 2005, repeated injections from depth fed the intermittent eruptive activity observed while silica-rich melts were produced by in-situ crystallization in the peripheral parts of the reservoir. In April 2006, the recharge of a primitive magma produced strong convection and homogenisation in the reservoir, as well as pressure increase and higher magma ascent rate after seven years of only moderately explosive activity. This work emphasizes the importance of petrological studies in constraining the pre-eruptive magmatic conditions and processes, as a tool for understanding the fundamental causes

  19. The 1883 eruption of Krakatau

    NASA Technical Reports Server (NTRS)

    Self, S.; Rampino, M. R.

    1981-01-01

    The 1883 eruption of Krakatau was a modest ignimbrite-forming event. The deposits are primarily coarse-grained dacitic, non-welded ignimbrite. Large explosions produced pyroclastic flows that entered the sea, generating destructive tsunami. Grain-size studies of the ignimbrite suggest that these explosions were not driven by magma-seawater interaction. The total bulk volume of pyroclastic deposits, including co-ignimbrite ash, is estimated to be 18-21 cu km.

  20. A kilohertz approach to Strombolian-style eruptions

    NASA Astrophysics Data System (ADS)

    Taddeucci, Jacopo; Scarlato, Piergiorgio; Del Bello, Elisabetta; Gaudin, Damien

    2015-04-01

    Accessible volcanoes characterized by persistent, relatively mild Strombolian-style explosive activity have historically hosted multidisciplinary studies of eruptions. These studies, focused on geophysical signals preceding, accompanying, and following the eruptions, have provided key insights on the physical processes driving the eruptions. However, the dynamic development of the single explosions that characterize this style of activity remained somewhat elusive, due to the timescales involved (order of 0.001 seconds). Recent technological advances now allow recording and synchronizing different data sources on time scales relevant to the short timescales involved in the explosions. In the last several years we developed and implemented a field setup that integrates visual and thermal imaging with acoustic and seismic recordings, all synchronized and acquired at timescales of 100-10000 Hz. This setup has been developed at several active volcanoes. On the one hand, the combination of these different techniques provides unique information on the dynamics and energetics of the explosions, including the parameterization of individual ejection pulses within the explosions, the ejection and emplacement of pyroclasts and their coupling-decoupling with the gas phases, the different stages of development of the eruption jets, and their reflection in the associated acoustic and seismic signals. On the other hand, the gained information provides foundation for better understanding and interpreting the signals acquired, at lower sampling rates but routinely, from volcano monitoring networks. Perhaps even more important, our approach allows parameterizing differences and commonalities in the explosions from different volcanoes and settings.

  1. The 2010 explosive eruption of Java's Merapi volcano—A '100-year' event

    NASA Astrophysics Data System (ADS)

    Surono; Jousset, Philippe; Pallister, John; Boichu, Marie; Buongiorno, M. Fabrizia; Budisantoso, Agus; Costa, Fidel; Andreastuti, Supriyati; Prata, Fred; Schneider, David; Clarisse, Lieven; Humaida, Hanik; Sumarti, Sri; Bignami, Christian; Griswold, Julie; Carn, Simon; Oppenheimer, Clive; Lavigne, Franck

    2012-10-01

    Merapi volcano (Indonesia) is one of the most active and hazardous volcanoes in the world. It is known for frequent small to moderate eruptions, pyroclastic flows produced by lava dome collapse, and the large population settled on and around the flanks of the volcano that is at risk. Its usual behavior for the last decades abruptly changed in late October and early November 2010, when the volcano produced its largest and most explosive eruptions in more than a century, displacing at least a third of a million people, and claiming nearly 400 lives. Despite the challenges involved in forecasting this 'hundred year eruption', we show that the magnitude of precursory signals (seismicity, ground deformation, gas emissions) was proportional to the large size and intensity of the eruption. In addition and for the first time, near-real-time satellite radar imagery played an equal role with seismic, geodetic, and gas observations in monitoring eruptive activity during a major volcanic crisis. The Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) issued timely forecasts of the magnitude of the eruption phases, saving 10,000-20,000 lives. In addition to reporting on aspects of the crisis management, we report the first synthesis of scientific observations of the eruption. Our monitoring and petrologic data show that the 2010 eruption was fed by rapid ascent of magma from depths ranging from 5 to 30 km. Magma reached the surface with variable gas content resulting in alternating explosive and rapid effusive eruptions, and released a total of ~ 0.44 Tg of SO2. The eruptive behavior seems also related to the seismicity along a tectonic fault more than 40 km from the volcano, highlighting both the complex stress pattern of the Merapi region of Java and the role of magmatic pressurization in activating regional faults. We suggest a dynamic triggering of the main explosions on 3 and 4 November by the passing seismic waves generated by regional earthquakes on

  2. Video monitoring analysis of the dynamics at fissure eruptions

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2016-04-01

    At basaltic eruption often lava fountains occur. The fountains mainly develop at erupting fissures, underlain by a magma-filled dike transporting the magma horizontally and vertically. Understanding of the dynamics of the deep dike and fracture mechanisms are mainly based on geophysical data as well as observations from seismic or geodetic networks. At the surface, however, new methods are needed to allow detailed interpretation on the eruption velocities, interactions between vents and complexities in the magma paths. With video cameras we collected imaging data from different erupting fissures. We find that lava fountaining is often correlated at distinct vents. From the frames of the videos we calculated the height and velocities of fountains as a function of time. Lava fountains often show a pulsating regime, that may change over time. Comparing the fountain height as a function of time of different vents by an time-dependent cross-correlation, we find a time lag between the pulses at adjacent vents. From this we derive an apparent velocity of temporal separation between vents, associated with the fountaining activity based on the calculated time lag and the vent distances. Although the correlation system can change episodically and sporadically, both the frequency of the fountains and eruption and the rest time between single fountains remain remarkably similar for adjacent lava fountains imply a controlling process in the magma feeder system itself. We present and compare our method for the Kamoamoa eruption 2011 (Hawaii) and the Holuhraun eruption 2014/2015 (Iceland). Both sites show a significant time shift between the single pulses of adjacent vents. We compare our velocities determined by this time shift to the assumed magma flow velocity in the dike as determined by independent models. Therefore we conjecture that the time shift of venting activity may allow to estimate the dynamics of magma and fluid migration at depth, as well as to identify the

  3. Medical effects of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Baxter, Peter J.

    1990-09-01

    Excluding famine and tsunamis, most deaths in volcanic eruptions have been from pyroclastic flows and surges (nuées ardentes) and wet debris flows (lahars). Information on the causes of death and injury in eruptions is sparse but the available literature is summarised for the benefit of volcanologists and emergency planners. In nuées, thermal injury may be at least as important as asphyxia in causing immediate deaths. The high temperature of the gases and entrained particles readily causes severe burns to the skin and the air passages and the presence of both types of injury in an individual may combine to increase the delayed mortality risk from respiratory complications or from infection of burns. Trauma from missiles or body displacement is also common, but the role of asphyxiant or irritant gases, and steam, remains unclear. The ratio of dead: injured is much higher than in other natural disasters. At the periphery of a nuée being protected inside buildings which remain intact appears to greatly increase the chances of survival. In lahars, infected wounds and crush injury are the main delayed causes of death, and the scope for preventive measures, other than evacuation, is small. The evidence from Mount St. Helens, 1980, and other major eruptions indicates that, although mortality is high within the main zone of devastation and in the open, emergency planning should concentrate on the periphery of a nuée where preventive measures are feasible and could save many lives in densely populated areas.

  4. Shallow conduit processes during the 1158 AD explosive eruption of Hekla volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Janebo, Maria; Houghton, Bruce; Thordarson, Thor; Larsen, Gudrun

    2015-04-01

    Hekla is one of the most frequently active silicic volcanic systems in the world, with multiple pre-historic large Plinian eruptions and 18 historical subplinian-Plinian eruptions. The common view is that the Plinian phases of the largest Hekla eruptions are all relatively homogeneous in style. Of the historical eruptions, only two were silicic: a Plinian eruption in 1104 and a smaller, less well characterized, eruption in 1158. We examine the dynamics of the 1158 eruption in detail with focus on the modulating role of shallow conduit processes. Grain size analysis, componentry, and density were used to characterize gradual and abrupt changes during the course of the eruption and quantitative vesicularity analysis was used to constrain the influence of bubble nucleation and coalescence. The 1158 eruption was a relatively steady, dry eruption with a more powerful opening phase followed by a lower intensity, waning phase accompanied by destabilization and collapse of the conduit walls. The juvenile pyroclasts are comprised of three types of microvesicular ragged pumice: white, grey, and banded. The abundance of grey pumice decreases as the eruption reaches maximum intensity, and then increases again during the waning phase of the eruption. The white pumices are more vesicular than the grey pumice, and the banded pumices have vesicularities that span predictably the range of the two end-members. The macroscopic differences between the white and grey pumice are accompanied by differences on a microscopic scale, most notably in a decrease in vesicle number density (VND) and a broadening of the vesicle size distribution, as well as increased crystal content. VND values of 0.5 to 1 E+6 mm-3 are similar to those recorded for the more powerful and sustained Plinian phases of the Novarupta 1912 and Taupo 181 eruptions in our laboratory. The 1158 pumice clasts display complex textures with adjacent domains of contrasting texture, alluding to complex nucleation, growth and

  5. The plinian fallout associated with Quilotoa's 800 yr BP eruption, Ecuadorian Andes

    NASA Astrophysics Data System (ADS)

    Mothes, Patricia A.; Hall, Minard L.

    2008-09-01

    Large volcanic eruptions at dacitic or rhyolitic volcanoes often generate exceptional volumes of fine ash that mantles an area up to a million km 2. These eruptions are characterized by extreme fragmentation of the magma and hence extraordinary dispersal of ash and are categorized as plinian, ultraplinian, or phreatoplinian events. Large-volume co-ignimbrites or co-plinian ashes are often produced by such eruptions. High fragmentation indices of > 90% are attributed to the violent eruption of silicic magma, especially if augmented by fuel-coolant reactions produced when abundant external water interacts with the magma. The present study documents a case where the fine ash (≤ 1 mm diameter) fall deposit related to the plinian phase of the eruption comprises the overwhelming bulk - about 87 wt.% of the eruptive products. This is another example demonstrating the predominance of a widespread, fine-grained, co-plinian ash which follows the initial coarser lapilli fall. Historical eruptions at two other Andean volcanoes Quizapu, (Chile) and Huaynaputina, (Peru), and at Santa Maria, (Guatemala) and Novarupta, (Alaska) produced similar ash fall sequences. Quilotoa's 800 yr BP eruption, in the Ecuadorian Andes, is an example of a powerful plinian eruption at a small dacitic volcano. It produced a crystal-rich, fine-grained ash layer which mantled an extrapolated ˜ 810,000 km 2 with ≥ 1 mm thickness and has a bulk magma volume of about 18.3 km 3. Stratigraphic and petrographic studies, as well as granulometric and density analyses were employed to investigate these eruptive products, particularly the distal co-plinian fall deposits. The eruptive cycle consisted of a phreatomagmatic triggering, the establishment of a powerful sustained plinian column and subsequently partial column collapses, leading to widespread surge and ash flow activity. Quilotoa's 800 yr BP eruption has a (VEI) Volcano Explosivity Index = 6, and generated a maximum column height of about 35 km and

  6. Geophysical Implications of Macro Variations in Enceladan Eruptions

    NASA Astrophysics Data System (ADS)

    Hurford, Terry; Hedman, Matthew M.; Spitale, Joseph N.; Rhoden, Alyssa R.

    2014-05-01

    Models of the evolution of Saturn's E ring have shown that Enceladus is the likely source of its particles [1]. Particles within this ring are quickly destroyed and must be constantly replenished [2,3]. Until recently the Enceladan source for these particles had been debated, but Cassini observations have tied their source to eruptions from a large fracture system in the south polar region. Cassini observations of the south pole of Enceladus revealed large rifts in the crust, informally called “tiger stripes”, which exhibit higher temperatures than the surrounding terrain and are likely sources of the observed plumes [4,5]. Diurnal tides due to Enceladus' orbital eccentricity were predicted to control the timing of eruptions as tidal stress varied across active faults on an orbital timescale [6]. These tidal stresses are periodic, driving motion along the rifts throughout Enceladus' orbit, influencing the timing and location of eruption as well as the formation and evolution of the E ring. Moreover, recent work has shown that Cassini has detected changes in the plume on orbital timescales [7], confirming the prediction of tidal control. Macro variations in eruptive plumes can be used to probe the conditions under which the eruptions occur [8]. We explore further the links between tidal control of eruptions and their geophysical implications.[1] M. Horanyi, et al., Icarus 97, 248 (1992). [2] P. K. Haff, et al., Icarus 56, 426 (1983). [3] S. Jurac, et al., Icarus 149, 384 (2001). [4] J. R. Spencer, et al., Science 311, 1401 (2006).[5] C. C. Porco, et al., Science 311, 1393 (2006).[6] T.A. Hurford, et al., Nature 447, 292 (2007).[7] M. Hedman, et al., Nature 500, 182 (2013).[8] T.A. Hurford, et al., Icarus 203, 541 (2009).

  7. New Insights into Basaltic Balloon Formation during Submarine Eruptions

    NASA Astrophysics Data System (ADS)

    Carey, S.; Kelly, J.; Rosi, M.; Pistolesi, M.; Marani, M.; Roman, C.; Croff Bell, K. L.

    2014-12-01

    Remotely operated vehicle (ROV) explorations in the area of the 1891 Foerstner submarine eruption (Pantelleria, Italy) during cruise NA-018 of the E/V Nautilus has provided the first examination of the vent site of a basaltic balloon-forming eruption. Ultra high-resolution bathymetric mapping defined a mound-like vent morphology in water depths of ~250 meter, constructed dominantly of highly vesicular scoriaceous fragments with minor pillow lava flows. The formation of floating basaltic balloons that reached the surface of the Strait of Sicily during the eruption is attributed to a hybrid Strombolian eruption mechanism that involved pre-concentration of volatiles into gas-rich portions of magma beneath the vent. An important difference of this Strombolian mechanism compared to its subaerial counterpart is the occurrence of buoyant magma discharge in the submarine environment caused by localized high gas contents. The added buoyancy flux modifies the fluid dynamic configuration of magma venting on the seafloor allowing for detachment of highly-inflated parcels of gas-rich magma. Some of these parcels contain large gas cavities that are enveloped in a partially quenched shell and maintain sufficient buoyancy to rise to the sea surface as a basaltic balloon. The majority of the vesicular magma maintains only partial positive buoyancy or negative buoyancy and is explosively fragmented to form large quantities of decimeter-scale fragments that accumulate close to the vent. Formation of the basaltic balloons is thus considered a somewhat accidental process that involves a subset of the total erupted volume of magma during the eruption. Suitable conditions for balloon formation include low magma viscosity, pre-concentration of gas, and moderate pressures (i.e.water depth). The dampening effect of seawater greatly reduces the dispersal of pyroclasts resulting in a mound-like vent morphology compared to subaerial scoria cones typically associated with Strombolian activity.

  8. Effects of megascale eruptions on Earth and Mars

    USGS Publications Warehouse

    Thordarson, T.; Rampino, M.; Keszthelyi, L.P.; Self, S.

    2009-01-01

    Volcanic features are common on geologically active earthlike planets. Megascale or "super" eruptions involving >1000 Gt of magma have occurred on both Earth and Mars in the geologically recent past, introducing prodigious volumes of ash and volcanic gases into the atmosphere. Here we discuss felsic (explosive) and mafi c (flood lava) supereruptions and their potential atmospheric and environmental effects on both planets. On Earth, felsic supereruptions recur on average about every 100-200,000 years and our present knowledge of the 73.5 ka Toba eruption implies that such events can have the potential to be catastrophic to human civilization. A future eruption of this type may require an unprecedented response from humankind to assure the continuation of civilization as we know it. Mafi c supereruptions have resulted in atmospheric injection of volcanic gases (especially SO2) and may have played a part in punctuating the history of life on Earth. The contrast between the more sustained effects of flood basalt eruptions (decades to centuries) and the near-instantaneous effects of large impacts (months to years) is worthy of more detailed study than has been completed to date. Products of mafi c supereruptions, signifi cantly larger than known from the geologic record on Earth, are well preserved on Mars. The volatile emissions from these eruptions most likely had global dispersal, but the effects may not have been outside what Mars endures even in the absence of volcanic eruptions. This is testament to the extreme variability of the current Martian atmosphere: situations that would be considered catastrophic on Earth are the norm on Mars. ?? 2009 The Geological Society of America.

  9. INSIGHTS INTO FILAMENT ERUPTION ONSET FROM SOLAR DYNAMICS OBSERVATORY OBSERVATIONS

    SciTech Connect

    Sterling, Alphonse C.; Moore, Ronald L.; Freeland, Samuel L. E-mail: ron.moore@nasa.gov

    2011-04-10

    We examine the buildup to and onset of an active region filament confined eruption of 2010 May 12, using EUV imaging data from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Array and line-of-sight magnetic data from the SDO Helioseismic and Magnetic Imager. Over the hour preceding eruption the filament undergoes a slow rise averaging {approx}3 km s{sup -1}, with a step-like trajectory. Accompanying a final rise step {approx}20 minutes prior to eruption is a transient preflare brightening, occurring on loops rooted near the site where magnetic field had canceled over the previous 20 hr. Flow-type motions of the filament are relatively smooth with speeds {approx}50 km s{sup -1} prior to the preflare brightening and appear more helical, with speeds {approx}50-100 km s{sup -1}, after that brightening. After a final plateau in the filament's rise, its rapid eruption begins, and concurrently an outer shell 'cocoon' of the filament material increases in emission in hot EUV lines, consistent with heating in a newly formed magnetic flux rope. The main flare brightenings start {approx}5 minutes after eruption onset. The main flare arcade begins between the legs of an envelope-arcade loop that is nearly orthogonal to the filament, suggesting that the flare results from reconnection among the legs of that loop. This progress of events is broadly consistent with flux cancellation leading to formation of a helical flux rope that subsequently erupts due to onset of a magnetic instability and/or runaway tether cutting.

  10. Combined Hinode, STEREO, and TRACE Observations of a Solar Filament Eruption: Evidence for Destabilization by Flux-Cancelation Tether Cutting

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, R. L.

    2007-01-01

    We present observations from Hinode, STEREO, and TRACE of a solar filament eruption and flare that occurred on 2007 March 2. Data from the two new satellites, combined with the TRACE observations, give us fresh insights into the eruption onset process. HINODE/XRT shows soft X-ray (SXR) activity beginning approximately 30 minutes prior to ignition of bright flare loops. STEREO andTRACE images show that the filament underwent relatively slow motions coinciding with the pre-eruption SXR brightenings, and it underwent rapid eruptive motions beginning near the time of flare onset. Concurrent HINODE/SOT magnetograms showed substantial flux cancelation under the filament at the site of the pre-eruption SXR activity. From these observations we infer that progressive tether-cutting reconnection driven by photospheric convection caused the slow rise of the filament and led to its eruption. NASA supported this work through a NASA Heliosphysics GI grant.

  11. Vent evolution and lag breccia formation during the Cape Riva eruption of Santorini, Greece.

    USGS Publications Warehouse

    Druitt, T.H.

    1985-01-01

    The 18 500 yr BP Cape Riva (CR) eruption of Santorini vented several km3 or more of magma, generating 4 eruption units, each of which is discussed. The eruption sampled a zoned magma chamber containing rhyodacite overlying andesite, and leaks of these magmas were manifested as the Skaros-Therasia lavas preceding the CR eruption. Plinian and initial ignimbrite stages occurred while the magma chamber was overpressured; subsequent underpressuring, due to magma discharge, caused fracturing of the chamber roof, caldera collapse, and eruption of pyroclastic flows from multiple vents. Activation and widening of new conduits during collapse resulted in the rapid escalation of discharge rate favoring the formation of lag breccias by: 1) promoting erosion of lithic debris at the surface vent; and 2) raising surface exit pressures, thereby resulting in a dramatic increase in the grain size of the ejecta.-from Author

  12. Interdisciplinary studies of eruption at Chaitén volcano, Chile

    USGS Publications Warehouse

    Pallister, John S.; Major, Jon J.; Pierson, Thomas C.; Holitt, Richard P.; Lowenstern, Jacob B.; Eichelberger, John C.; Luis, Lara; Moreno, Hugo; Muñoz, Jorge; Castro, Jonathan M.; Iroumé, Andrés; Andreoli, Andrea; Jones, Julia; Swanson, Fred; Crisafulli, Charlie

    2010-01-01

    High-silica rhyolite magma fuels Earth's largest and most explosive eruptions. Recurrence intervals for such highly explosive eruptions are in the 100- to 100,000-year time range, and there have been few direct observations of such eruptions and their immediate impacts. Consequently, there was keen interest within the volcanology community when the first large eruption of high-silica rhyolite since that of Alaska's Novarupta volcano in 1912 began on 1 May 2008 at Chaitén volcano, southern Chile, a 3-kilometer-diameter caldera volcano with a prehistoric record of rhyolite eruptions [Naranjo and Stern, 2004semi; Servicio Nacional de Geología y Minería (SERNAGEOMIN), 2008semi; Carn et al., 2009; Castro and Dingwell, 2009; Lara, 2009; Muñoz et al., 2009]. Vigorous explosions occurred through 8 May 2008, after which explosive activity waned and a new lava dome was extruded.

  13. Interdisciplinary Studies of Eruption at Chaitén Volcano, Chile

    NASA Astrophysics Data System (ADS)

    Pallister, John S.; Major, Jon J.; Pierson, Thomas C.; Hoblitt, Richard P.; Lowenstern, Jacob B.; Eichelberger, John C.; Lara, Luis; Moreno, Hugo; Muñoz, Jorge; Castro, Jonathan M.; Iroumé, Andrés; Andreoli, Andrea; Jones, Julia; Swanson, Fred; Crisafulli, Charlie

    2010-10-01

    High-silica rhyolite magma fuels Earth's largest and most explosive eruptions. Recurrence intervals for such highly explosive eruptions are in the 100- to 100,000­year time range, and there have been few direct observations of such eruptions and their immediate impacts. Consequently, there was keen interest within the volcanology community when the first large eruption of high-silica rhyolite since that of Alaska's Novarupta volcano in 1912 began on 1 May 2008 at Chaitén volcano, southern Chile, a 3-kilometer­diameter caldera volcano with a prehistoric record of rhyolite eruptions [Naranjo and Stern, 2004; Servicio Nacional de Geología y Minería (SERNAGEOMIN), 2008; Carn et al., 2009; Castro and Dingwell, 2009; Lara, 2009; Muñoz et al., 2009]. Vigorous explosions occurred through 8 May 2008, after which explosive activity waned and a new lava dome was extruded.

  14. Genome patent fight erupts

    SciTech Connect

    Roberts, L.

    1991-10-11

    At a Congressional briefing while describing a new project to sequence partially every gene active in the human brain, it was made known that the National Institutes of Health was planning to file patent applications on 1,000 of these sequences a month. The scheme has engendered a firestorm of criticism from genome scientists and project officials alike. The critics argue that these sequences probably can't be patented in the first place - and even if they can, they shouldn't be. The plan would undercut patent protection for those who labor long and hard at the real task of elucidating the function of the proteins encoded by the genes, thereby driving industry away from developing inventions based on that work.

  15. 1891 Submarine eruption of Foerstner volcano (Pantelleria, Sicily) : insights into the vent structure of basaltic balloon eruptions

    NASA Astrophysics Data System (ADS)

    Kelly, J. T.; Carey, S.; Bell, K. L.; Rosi, M.; Marani, M.; Roman, C.; Pistolesi, M.; Baker, E. T.

    2012-12-01

    Numerous shallow water basaltic eruptions have produced abundant floating scoria up to several meters in diameter, yet little is known about the conditions that give rise to this unusual style of volcanism. On October 17, 1891, a submarine eruption began 4 kilometers northwest of the island of Pantelleria, Sicily. The eruptive vent was located at a depth of 250 meters along the NW-SE trending Sicily Channel Rift Zone. Evidence for the eruption was provided by the occurrence of hot, scoriaceous lava "balloons" floating on the sea surface along a narrow line about 850-1000 meters long trending along the rift. These extremely vesicular fragments were spherical to ellipsoidal in shape and ranged from <50 to 250 cm in diameter. Remotely Operated Vehicles (ROVs) and existing bathymetric maps have been used to conduct the first detailed investigation of a vent site associated with this unique style of volcanism. In 2011 the ROV Hercules, deployed from the E/V Nautilus, explored the 1891 Foerstner vent using high definition video cameras and produced a high resolution bathymetric map of the area using a BlueView multibeam imaging sonar. Light backscattering and oxidation-reduction potential sensors (MAPRs) were added to Hercules to detect discharge from active venting. ROV video footage has been used in conjunction with the high resolution bathymetric data to construct a geologic map of the vent area based on a variety of facies descriptors, such as abundance of scoria bombs, occurrence of pillow or scoria flow lobes, extent of sediment cover, and presence of spatter-like deposits. Initial results of the mapping have shown that there are two main vents that erupted within the observed area of floating scoria and most likely erupted at the same time as evidenced by similar bulk chemical compositions of recovered samples. Scoria bomb beds and some scoria flow lobes largely cover the suspected main vent, located at a depth of 250 meters. Distinct pillow flow lobes cover the

  16. Pigeonholing pyroclasts: Insights from the 19 March 2008 explosive eruption of Kīlauea volcano

    USGS Publications Warehouse

    Houghton, B.F.; Swanson, D.A.; Carey, R.J.; Rausch, J.; Sutton, A.J.

    2011-01-01

    We think, conventionally, of volcanic explosive eruptions as being triggered in one of two ways: by release and expansion of volatiles dissolved in the ejected magma (magmatic explosions) or by transfer of heat from magma into an external source of water (phreatic or phreatomagmatic explosions). We document here an event where neither magma nor an external water source was involved in explosive activity at K??lauea. Instead, the eruption was powered by the expansion of decoupled magmatic volatiles released from deeper magma, which was not ejected by the eruption, and the trigger was a collapse of near-surface wall rocks that then momentarily blocked that volatile flux. Mapping of the advected fall deposit a day after this eruption has highlighted the difficulty of constraining deposit edges from unobserved or prehistoric eruptions of all magnitudes. Our results suggest that the dispersal area of advected fall deposits could be miscalculated by up to 30% of the total, raising issues for accurate hazard zoning and assessment. Eruptions of this type challenge existing classification schemes for pyroclastic deposits and explosive eruptions and, in the past, have probably been interpreted as phreatic explosions, where the eruptive mechanism has been assumed to involve flashing of groundwater to steam. ?? 2011 Geological Society of America.

  17. Two Types of Magnetic Flux Cancellation in the Solar Eruption of 2007 May 20

    NASA Technical Reports Server (NTRS)

    Sterlin, Alphonse C.; Moore, Ronald L.; Mason, Helen

    2010-01-01

    We study a solar eruption of 2007 May 20, in an effort to understand the cause of the eruption's onset. The event produced a GOES class B6.7 flare peaking at 05:56 UT, while ejecting a surge/filament and producing a coronal mass ejection (CME). We examine several data sets, including H-alpha images from the Solar Optical Telescope (SOT) on Hinode, EUV images from TRACE, and line-of-sight magnetograms from SOHO/MDI. Flux cancelation occurs among two different sets of flux elements inside of the erupting active region: First, for several days prior to eruption, opposite-polarity sunspot groups inside the region move toward each other, leading to the cancelation of approximately 10^{21} Mx of flux over three days. Second, within hours prior to the eruption, positive-polarity moving magnetic features (MMFs) flowing out of the positive-flux spots at approximately 1 kilometer per second repeatedly cancel with field inside a patch of negative-polarity flux located north of the sunspots. The filament erupts as a surge whose base is rooted in the location where the MMF cancelation occurs, while during the eruption that filament flows out along the polarity inversion line between the converging spot groups. We conclude that a plausible scenario is that the converging spot fields brought the magnetic region to the brink of instability, and the MMF cancelation pushed the system "over the edge." triggering the eruption.

  18. Identifying the locations of future eruptions within large calderas: Campi Flegrei, Southern Italy.

    NASA Astrophysics Data System (ADS)

    Charlton, Danielle; Kilburn, Christopher; Sobradelo, Rosa; Edwards, Stephen

    2016-04-01

    Large calderas, with surface areas of 100 km2 or more, are among the most populated active volcanoes on Earth. New vents commonly open at locations across the caldera floor. An important goal for hazard mitigation, therefore, is to develop reliable methods for evaluating the most likely location for a future eruption. A preferred approach is to analyse statistically the distributions of previous vents. Using the Campi Flegrei caldera as a test case, we here examine the sensitivity of results to starting assumptions, notably the choice of data set for defining preferred vent locations. Situated immediately west of Naples, in southern Italy, Campi Flegrei poses a direct threat to more than 300,000 people. It has been in episodic unrest since the late 1950s. The unrest is the first since the last eruption in Campi Flegrei in 1538 and suggests that the caldera may have re-entered a state with an increased probability of an eruption. Since the most recent episode of caldera collapse 15.5 ka BP, at least 60 intra-caldera eruptions have occurred across the 150 km2 that make up the modern onshore area of Campi Flegrei. The eruptions have been concentrated within three epochs: 15.5-9.5 ka BP (Epoch 1, c. 27 eruptions), 8.6-8.2 ka BP (Epoch 2; c. 6 eruptions) and 4.8-3.8 ka BP (Epoch 3; c. 27 eruptions). Recent statistical studies of future vent locations have assumed that (1) only data from Epoch 3 are relevant to modern Campi Flegrei, and (2) repeated eruptions from the same vent can be incorporated, whether they are independent events or belong to a connected sequence of activity. We have relaxed these assumptions to investigate data from all epochs and to distinguish between independent and related eruptions from the same vent. Quadrat and nearest-neighbour statistics show that eruptions from Epochs 1 and 2 were distributed within an annulus 3-5 km around modern Pozzuoli, but that, in agreement with previous studies, eruptions occurred preferentially NE-ENE of Pozzuoli

  19. 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.

  20. Eruption Forecasting in Alaska: A Retrospective and Test of the Distal VT Model

    NASA Astrophysics Data System (ADS)

    Prejean, S. G.; Pesicek, J. D.; Wellik, J.; Cameron, C.; White, R. A.; McCausland, W. A.; Buurman, H.

    2015-12-01

    United States volcano observatories have successfully forecast most significant US eruptions in the past decade. However, eruptions of some volcanoes remain stubbornly difficult to forecast effectively using seismic data alone. The Alaska Volcano Observatory (AVO) has responded to 28 eruptions from 10 volcanoes since 2005. Eruptions that were not forecast include those of frequently active volcanoes with basaltic-andesite magmas, like Pavlof, Veniaminof, and Okmok volcanoes. In this study we quantify the success rate of eruption forecasting in Alaska and explore common characteristics of eruptions not forecast. In an effort to improve future forecasts, we re-examine seismic data from eruptions and known intrusive episodes in Alaska to test the effectiveness of the distal VT model commonly employed by the USGS-USAID Volcano Disaster Assistance Program (VDAP). In the distal VT model, anomalous brittle failure or volcano-tectonic (VT) earthquake swarms in the shallow crust surrounding the volcano occur as a secondary response to crustal strain induced by magma intrusion. Because the Aleutian volcanic arc is among the most seismically active regions on Earth, distinguishing distal VT earthquake swarms for eruption forecasting purposes from tectonic seismicity unrelated to volcanic processes poses a distinct challenge. In this study, we use a modified beta-statistic to identify pre-eruptive distal VT swarms and establish their statistical significance with respect to long-term background seismicity. This analysis allows us to explore the general applicability of the distal VT model and quantify the likelihood of encountering false positives in eruption forecasting using this model alone.

  1. An ergodic approach to eruption hazard scaling

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The complexity and indeterminacy of volcanic processes demand the use of statistical methods to analyze the expectations of the occurrence and size of future eruptions. The probability of a volcano producing potentially destructive eruptions in a given time interval may be estimated analyzing the sequence of past eruptions assuming a physically plausible process. Since the threat posed by eruptions depends on their mass or energy release (magnitude) and on their emission rate (intensity), the Volcanic Explosivity Index is a suitable measure to quantify the eruptive events, particularly considering that the largest available global catalogues use that measure. The definition of volcanic hazard is thus posed here in terms of the expected annual release of energy by eruptions in each VEI category. This concept is based on the ergodic property of a large set of volcanoes to release about the same amount of energy in each VEI category over a sufficiently large time interval. This property is however constrained to the VEI range of eruptions that constitute complete catalogues (VEI >2) in the lower end, and to the extreme eruptions that may destroy or significantly alter a volcanic system, such as the large caldera-forming eruptions (VEI < 7). In such conditions, a simple power law for eruptions at the global level relating the global rate of energy release to the eruption magnitude has been proposed as a statistical basis for eruptive event model development. Following the above mentioned arguments, we assume that a similar scaling law rules the annual rate at which energy is released by eruptions at individual volcanoes as log(EmRm)=bM+a, where Em is the energy released by eruptions in the VEI magnitude class M, and Rm is the occurrence rate of such eruptions over times ranges in which catalogues may be considered complete. The parameters b and a depend on the eruptive history of individual volcanoes, the former determining the preferred mode of the volcano to release

  2. Volcanic Eruptions and Climate: Outstanding Research Issues

    NASA Astrophysics Data System (ADS)

    Robock, Alan

    2016-04-01

    Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of this aerosol cloud produce responses in the climate system. Based on observations after major eruptions of the past and experiments with numerical models of the climate system, we understand much about their climatic impact, but there are also a number of unanswered questions. Volcanic eruptions produce global cooling, and are an important natural cause of interannual, interdecadal, and even centennial-scale climate change. One of the most interesting volcanic effects is the "winter warming" of Northern Hemisphere continents following major tropical eruptions. During the winter in the Northern Hemisphere following every large tropical eruption of the past century, surface air temperatures over North America, Europe, and East Asia were warmer than normal, while they were colder over Greenland and the Middle East. This pattern and the coincident atmospheric circulation correspond to the positive phase of the Arctic Oscillation. While this response is observed after recent major eruptions, most state-of-the-art climate models have trouble simulating winter warming. Why? High latitude eruptions in the Northern Hemisphere, while also producing global cooling, do not have the same impact on atmospheric dynamics. Both tropical and high latitude eruptions can weaken the Indian and African summer monsoon, and the effects can be seen in past records of flow in the Nile and Niger Rivers. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade have had a small effect on global temperature trends. Some important outstanding research questions include: How much seasonal, annual, and decadal predictability is possible following a large volcanic eruption? Do

  3. Eruptive and Geomorphic Processes at the Lathrop Wells Scoria Cone

    SciTech Connect

    G. Valentine; D.J. Krier; F.V. Perry; G. Heiken

    2006-08-03

    The {approx}80 ka Lathrop Wells volcano (southern Nevada, U.S.A.) preserves evidence for a range of explosive processes and emplacement mechanisms of pyroclastic deposits and lava fields in a small-volume basaltic center. Early cone building by Strombolian bursts was accompanied by development of a fan-like lava field reaching {approx}800 m distance from the cone, built upon a gently sloping surface. Lava flows carried rafts of cone deposits, which provide indirect evidence for cone facies in lieu of direct exposures in the active quarry. Subsequent activity was of a violent Strombolian nature, with many episodes of sustained eruption columns up to a few km in height. These deposited layers of scoria lapilli and ash in different directions depending upon wind direction at the time of a given episode, reaching up to {approx}20 km from the vent, and also produced the bulk of the scoria cone. Lava effusion migrated from south to north around the eastern base of the cone as accumulation of lavas successively reversed the topography at the base of the cone. Late lavas were emplaced during violent Strombolian activity and continued for some time after explosive eruptions had waned. Volumes of the eruptive products are: fallout--0.07 km{sup 3}, scoria cone--0.02 km{sup 3}, and lavas--0.03 km{sup 3}. Shallow-derived xenolith concentrations suggest an upper bound on average conduit diameter of {approx}21 m in the uppermost 335 m beneath the volcano. The volcano was constructed over a period of at least seven months with cone building occurring only during part of that time, based upon analogy with historical eruptions. Post-eruptive geomorphic evolution varied for the three main surface types that were produced by volcanic activity: (1) scoria cone, (2) low relief surfaces (including lavas) with abundant pyroclastic material, and (3) lavas with little pyroclastic material. The role of these different initial textures must be accounted for in estimating relative ages of

  4. Eruptive and Geomorphic Processes at Lathrop Wells Scoria Cone Volcano

    NASA Astrophysics Data System (ADS)

    Krier, D. J.; Valentine, G. A.; Perry, F. V.; Heiken, G.

    2006-12-01

    The ~80 ka Lathrop Wells volcano (southern Nevada, U.S.A.) preserves evidence for a range of explosive processes and emplacement mechanisms of pyroclastic deposits and lava fields in a small-volume basaltic center. Early cone building by Strombolian bursts was accompanied by development of a fan-like lava field reaching ~800 m distance from the cone, built upon a gently sloping surface. Lava flows carried rafts of cone deposits, which provide indirect evidence for cone facies in lieu of direct exposures in the active quarry. Subsequent activity was of a violent Strombolian nature, with many episodes of sustained eruption columns up to a few km in height. These deposited layers of scoria lapilli and ash in different directions depending upon wind direction at the time of a given episode, reaching up to ~20 km from the vent, and also produced the bulk of the scoria cone. Lava effusion migrated from south to north around the eastern base of the cone as accumulation of lavas successively reversed the topography at the base of the cone. Late lavas were emplaced during violent Strombolian activity and continued for some time after explosive eruptions had waned. Volumes of the eruptive products are: fallout - 0.07 km3, scoria cone - 0.02 km3, and lavas - 0.03 km3. Shallow-derived xenolith concentrations suggest an upper bound on average conduit diameter of ~21 m in the uppermost 335 m beneath the volcano. The volcano was constructed over a period of at least seven months with cone building occurring only during part of that time, based upon analogy with historical eruptions. Post-eruptive geomorphic evolution varied for the three main surface types that were produced by volcanic activity: (1) scoria cone, (2) low relief surfaces (including lavas) with abundant pyroclastic material, and (3) lavas with little pyroclastic material. The role of these different initial textures must be accounted for in estimating relative ages of volcanic surfaces, and failure to account for

  5. Critical Decay Index at the Onset of Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Zuccarello, F. P.; Aulanier, G.; Gilchrist, S. A.

    2015-12-01

    Magnetic flux ropes are topological structures consisting of twisted magnetic field lines that globally wrap around an axis. The torus instability model predicts that a magnetic flux rope of major radius R undergoes an eruption when its axis reaches a location where the decay index -d({ln}{B}{ex})/d({ln}R) of the ambient magnetic field Bex is larger than a critical value. In the current-wire model, the critical value depends on the thickness and time evolution of the current channel. We use magnetohydrodynamic simulations to investigate whether the critical value of the decay index at the onset of the eruption is affected by the magnetic flux rope’s internal current profile and/or by the particular pre-eruptive photospheric dynamics. The evolution of an asymmetric, bipolar active region is driven by applying different classes of photospheric motions. We find that the critical value of the decay index at the onset of the eruption is not significantly affected by either the pre-erupitve photospheric evolution of the active region or the resulting different magnetic flux ropes. As in the case of the current-wire model, we find that there is a “critical range” [1.3-1.5], rather than a “critical value” for the onset of the torus instability. This range is in good agreement with the predictions of the current-wire model, despite the inclusion of line-tying effects and the occurrence of tether-cutting magnetic reconnection.

  6. Forces in Erupting Flux Ropes: CMEs and Failed Eruptions

    NASA Astrophysics Data System (ADS)

    Chen, James

    2016-05-01

    A range of dynamical behaviors that can be exhibited by a quasi-statically evolving flux rope is studied. Starting with a CME-like flux rope in equilibrium balanced by the ambient coronal pressure (non-force-free) and an overlying coronal magnetic field (Bc), the poloidal flux is slowly increased, on a timescale much longer than the eruptive timescale of several to tens of minutes. In this configuration, the overlying field Bc provides an external downward restraining force, constituting an effective potential barrier. Slowly increasing poloidal flux causes the flux rope to gradually rise, following a sequence of quasi-static equilibria. As the apex of the flux rope rises past a critical height Z*, slightly higher than the peak of the potential barrier Bc(Z), it expands on a faster, dynamical (Alfvenic) timescale determined by the magnetic field and geometry of the flux rope. The expanding flux rope may reach a new equilibrium at height Z1. Observationally, this behavior would be recognized as a ``failed eruption.'' The new equilibrium flux rope is established if the magnetic tension force due to the toroidal magnetic field component Bt can balance the outward hoop force due to the poloidal component Bp. The flux rope may also expand without reaching a new equilibrium, provided a sufficiennt amount of poloidal flux is injected on a dynamical timescale so that the tension force cannot balance the hoop force. This scenario would result in a CME eruption. The influence of the poloidal flux injection, the Bc(Z) profile, and boundary conditions on the quantitative balance of the forces in an expanding flux rope is elucidated. Potentially observable consequences of the difference scenarios/models are discussed.Work supported by the Naval Research Laboratory Base Research Program

  7. Magma migration at the onset of the 2012-13 Tolbachik eruption revealed by Seismic Amplitude Ratio Analyses

    NASA Astrophysics Data System (ADS)

    Taisne, B.; Caudron, C.; Kugaenko, Y.; Saltykov, V.

    2015-12-01

    In contrast of the 1975-76 Tolbachik eruption, the 2012-2013 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma transfer prior to this important eruption. We highlighted a clear migration of the source of the microseismicity within the seismic swarm, starting 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava extrusion, was recorded (at ~11:00 UTC, 27 November 2012). In order to get a first order approximation of the location of the magma, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest a migration toward the eruptive vent. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano that would interact at shallower depth with an intermediate storage region and initiate the lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16-20 km to the south of Plosky Tolbachik at 20:31 UTC on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975-76 Tolbachik eruption and can be considered as a possible aborted eruption.

  8. Magma migration at the onset of the 2012-13 Tolbachik eruption revealed by Seismic Amplitude Ratio Analysis

    NASA Astrophysics Data System (ADS)

    Caudron, Corentin; Taisne, Benoit; Kugaenko, Yulia; Saltykov, Vadim

    2015-12-01

    In contrast of the 1975-76 Tolbachik eruption, the 2012-13 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma movement prior to this important eruption. A clear seismic migration within the seismic swarm, started 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava flows, was recorded (at ~ 11:00 UTC, 27 November 2012). In order to get a first order approximation of the magma location, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest that the seismicity migrated toward the eruption location. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano followed by a lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16-20 km to the south of Plosky Tolbachik at 20:31 UTC on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975-76 Tolbachik eruption and can be considered as a possible aborted eruption.

  9. Eruptive modes and hiatus of volcanism at West Mata seamount, NE Lau basin: 1996-2012

    NASA Astrophysics Data System (ADS)

    Embley, Robert W.; Merle, Susan G.; Baker, Edward T.; Rubin, Kenneth H.; Lupton, John E.; Resing, Joseph A.; Dziak, Robert P.; Lilley, Marvin D.; Chadwick, William W.; Shank, T.; Greene, Ron; Walker, Sharon L.; Haxel, Joseph; Olson, Eric; Baumberger, Tamara

    2014-10-01

    present multiple lines of evidence for years to decade-long changes in the location and character of volcanic activity at West Mata seamount in the NE Lau basin over a 16 year period, and a hiatus in summit eruptions from early 2011 to at least September 2012. Boninite lava and pyroclasts were observed erupting from its summit in 2009, and hydroacoustic data from a succession of hydrophones moored nearby show near-continuous eruptive activity from January 2009 to early 2011. Successive differencing of seven multibeam bathymetric surveys of the volcano made in the 1996-2012 period reveals a pattern of extended constructional volcanism on the summit and northwest flank punctuated by eruptions along the volcano's WSW rift zone (WSWRZ). Away from the summit, the volumetrically largest eruption during the observational period occurred between May 2010 and November 2011 at ˜2920 m depth near the base of the WSWRZ. The (nearly) equally long ENE rift zone did not experience any volcanic activity during the 1996-2012 period. The cessation of summit volcanism recorded on the moored hydrophone was accompanied or followed by the formation of a small summit crater and a landslide on the eastern flank. Water column sensors, analysis of gas samples in the overlying hydrothermal plume and dives with a remotely operated vehicle in September 2012 confirmed that the summit eruption had ceased. Based on the historical eruption rates calculated using the bathymetric differencing technique, the volcano could be as young as several thousand years.

  10. Controls on the explosivity of scoria cone eruptions: Magma segregation at conduit junctions

    NASA Astrophysics Data System (ADS)

    Pioli, L.; Azzopardi, B. J.; Cashman, K. V.

    2009-10-01

    Violent strombolian (transitional) eruptions are common in mafic arc settings and are characterized by simultaneous explosive activity from scoria cone vents and lava effusion from lateral vents. This dual activity requires magma from the feeder conduit to split into vertical and lateral branches somewhere near the base of the scoria cone. Additionally, if the flow is separated, gas and liquid (+ crystals) components of the magma may be partitioned unevenly between the two branches. Because flow separation requires bubbles to move independently of the liquid over time scales of magma ascent separation is promoted by low magma viscosities and by high magma H 2O content (i.e. sufficiently deep bubble nucleation to allow organization of the gas and liquid phases during magma ascent). Numerical modeling shows that magma and gas distribution between vertical and horizontal branches of a T-junction is controlled by the mass flow rate and the geometry of the system, as well as by magma viscosity. Specifically, we find that mass eruption rates (MERs) between 10 3 and 10 5 kg/s allow the gas phase to concentrate within the central conduit, significantly increasing explosivity of the eruption. Lower MERs produce either strombolian or effusive eruption styles, while MER > 10 5 kg/s prohibit both gas segregation and lateral magma transport, creating explosive eruptions that are not accompanied by effusive activity. These bracketing MER constraints on eruptive transitions are consistent with field observations from recent eruptions of hydrous mafic magmas.

  11. Effects of shallow subvolcanic magma storage regions on magma evolution and eruptions dynamics of small mafic centers

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.; Wallace, P. J.; McKay, D.; Ruscitto, D. M.

    2009-12-01

    The existence of shallow subvolcanic dike and sill complexes has long been recognized in field investigations of mafic cinder cones and shield volcanoes. Evidence that these subvolcanic storage regions develop during (rather than separate from) eruptive activity comes from detailed studies of tephra deposits and lava flows produced during cinder cone eruptions. These deposits show both the variable volatile contents of olivine-hosted melt inclusions and pervasive microphenocryst crystallization, both of which indicate temporary magma storage at shallow levels prior to eruption. The consequences of such shallow magma storage for both eruption dynamics and syn-eruptive magma evolution have not previously been considered. Here we use both physical (density, crystallinity) and compositional (bulk, melt inclusion) data from the 1943-1952 eruption of Parícutin, Mexico to examine the impact of shallow pre-eruptive storage on both the eruption process and on the dramatic evolution in magma composition first described by Wilcox (1954). We supplement these observations with data from recent (1500-2000 ybp) mafic cinder cone eruptions in central Oregon. Our data show that shallow subvolcanic storage of magma permits pre-eruptive degassing and crystallization, which, in turn, are responsible for the (typically) wide density range of basaltic scoria observed in cinder cone activity. As pre-eruptive gas loss will diminish the volatiles available to fuel explosive activity, we further speculate that the ease of syn-eruptive dike and sill formation, which is likely to be controlled by both the rate of magma supply and the specific tectonic setting, may modulate the explosive potential of cinder cone eruptions. Additionally, all of the deposits that we have studied have a range in bulk composition, with the earliest tephra the most mafic and the latest lava the most silicic of the eruptive sequence. This observation suggests that an additional consequence of shallow magma storage

  12. Impact of explosive eruption scenarios at Vesuvius

    NASA Astrophysics Data System (ADS)

    Zuccaro, G.; Cacace, F.; Spence, R. J. S.; Baxter, P. J.

    2008-12-01

    In the paper the first attempt at the definition of a model to assess the impact of a range of different volcanic hazards on the building structures is presented. This theoretical approach has been achieved within the activities of the EXPLORIS Project supported by the EU. A time history for Sub-Plinian I eruptive scenario of the Vesuvius is assumed by taking advantage of interpretation of historical reports of volcanic crises of the past [Carafa, G. 1632. In opusculum de novissima Vesuvij conflagratione, epistola isagogica, 2 a ed. Napoli, Naples; Mascolo, G.B., 1634. De incendio Vesuvii excitato xvij. Kal. Ianuar. anno trigesimo primo sæculi Decimiseptimi libri X. Cum Chronologia superiorum incendiorum; & Ephemeride ultimi. Napoli; Varrone, S., 1634. Vesuviani incendii historiae libri tres. Napoli], numerical simulations [Neri, A., Esposti Ongaro, T., Macedonio, G., Gidaspow, D., 2003. Multiparticle simulation of collapsing volcanic columns and pyroclastic flows. J. Geophys. Res. Lett. 108, 2202. doi:10.1029/2001 JB000508; Macedonio, G., Costa, A., Longo, A., 2005. HAZMAP: a computer model for volcanic ash fallout and assessment of subsequent hazard. Comput. Geosci. 31,837-845; Costa, A., Macedonio, G., Folch, A., 2006. A three-dimensional Eulerian model for transport and deposition of volcanic ashes. Earth Planet. Sci. Lett. 241,634-647] and experts' elicitations [Aspinall, W.P., 2006. Structured elicitation of expert judgment for probabilistic hazard and risk assessment in volcanic eruptions. In: Mader, H.M. Coles, S.G. Connor, C.B. Connor, L.J. (Eds), Statistics in Volcanology. Geological Society of London on behalf of IAVCEI, pp.15-30; Woo, G., 1999. The Mathematics of Natural Catastrophes. Imperial College Press, London] from which the impact on the building structures is derived. This is achieved by an original definition of vulnerability functions for multi-hazard input and a dynamic cumulative damage model. Factors affecting the variability of the final

  13. Adverse reaction of topical etofenamate: petechial eruption.

    PubMed

    Orbak, Z; Yildirim, Z K; Sepetci, O; Karakelleoglu, C; Alp, H

    2012-10-01

    Etofenamate is a non-steroidal anti-inflammatory drug (NSAID). Clinical findings caused by etofenamate are uncommon. Allergic contact dermatitis is the most common cutaneous reaction reported. But petechial eruption due to etofenamate had not been reported yet. This report concerns an 11-year old male with petechial eruption after application of topical etofenamate. Physicians need to be aware that patients can develop an asymptomatic purpuric eruption when etofenamate is ordered. PMID:23620980

  14. How and Why Do Geysers Erupt?

    NASA Astrophysics Data System (ADS)

    Manga, M.

    2014-12-01

    Geysers are features that produce episodic eruptions of water, steam and sometimes non-condensable gases. Natural geysers are rare, with fewer than 1,000 worldwide. They are more than curiosities and popular tourist attractions: they offer a direct window into geothermal processes, and may serve as a natural small-scale laboratory to study larger-scale eruptive process such as those at volcanoes, and other self-organized, intermittent processes that result from phase separation and localized input of energy and mass. Despite > 200 years of scientific study, basic questions remain: Do eruptions begin from the bottom or top of the geyser? What controls eruption duration? Why do eruptions end? What are the required special subsurface geometries? Why are some geysers periodic, and others irregular? How and why do they respond to external influences such as weather, tides, and earthquakes? This presentation will review new insights from field studies at Lone Star geyser, Yellowstone National Park, geysers in the El Tatio geyser field, Chile, and laboratory models. At Lone Star we infer that dynamics are controlled by thermal and mechanical coupling between the conduit and a deeper, laterally-offset reservoir (called a "bubble trap" in previous studies). At El Tatio, we measured pressure and temperature within geysers over multiple eruption cycles: this data document the heating of liquid water by steam delivered from below. The laboratory experiments reveal how episodic release of steam from a bubble trap prepares a conduit for eruption and can generate a range of eruption intensities. In all cases, the eruption initiation, duration and termination are controlled by the interaction between the accumulation and transport of steam and liquid, and modulated by the geometry of the geyser's plumbing. Time series of thousands of eruptions confirm that internal processes control eruptions, with only pool geysers showing a sensitivity to air temperature; only very large stress

  15. Hybrid Pyroclastic Deposits Accumulated From The Eruptive Transitional Regime of Plinian Eruptions.

    NASA Astrophysics Data System (ADS)

    di Muro, Andrea; Rosi, Mauro

    In the past 15 years sedimentological studies (Valentine and Giannetti, 1995; Wilson and Hildreth, 1997; Rosi et al., 2001), physical models (Neri et al., 1988; Veitch and Woods, 2000; Kaminski and Jaupart, 2001) and laboratory experiments (Carey et al., 1988) converge at defining a new eruptive regime transitional between the fully convective and the fully collapsing end -members. Buoyant columns and density currents are contemporaneously fed in the transitional dynamic regime and fall beds are intercalated with the density current deposits in the area invested by them. The sedimentological analysis of the well exposed 800yr B.P. plinian eruption of the volcano Quilotoa (Ecuador) enabled us to i) recognize a gradual evolution of the eruptive regime, ii) characterize the fall and density current deposits emplaced during the transitional regime. The eruptive activity began with at least two phreatic explosions and the effusion of a small volume lava dome. Eruptive behaviour then switched to explosive and fed a purely convective column that accumulated a reverse graded pumice fall while rising up to an height of 30 km. A small volume, diluted and slow density current (S1 current) was emplaced in the proximal SW sector just before the column reached its maximum height. Two group s of more voluminous and faster intra-plinian density currents (S2 and S3 currents) were subsequently emplaced contemporaneously with the accumulation of the lower and upper part respectively of a normal graded pumice fall bed. S2 and S3 currents were radially distributed around the crater and deposited bedded layers with facies of decreasing energy when moving away from the crater. Massive beds of small volume were emplaced only i) inside the proximal valley channel near the topography break in slope, ii) outside the valley channel in medial area where the currents impinged against relieves. A thick sequence of pyroclastic flow deposits (S4 currents) accumulated in the valley channels around

  16. Tracking effusive eruptions in near real-time: 2014 Fogo (Cape Verde) eruption

    NASA Astrophysics Data System (ADS)

    Laiolo, Marco; Coppola, Diego; Cigolini, Corrado; Faria, Bruno; Ripepe, Maurizio

    2015-04-01

    The Fogo volcano (Cape Verde), after almost 20 years of inactivity, entered in a new effusive phase on November 23, 2014. The eruption occurred on the Fogo's Pico cone inside the Cha Caldera where the lava flow caused the evacuation of the Bangaeira and Portela inhabitants. To track the thermal evolution of this eruption, we extended the near-real time processing of the MIROVA (Middle InfraRed Observation of Volcanic Activity) algorithm to Fogo island. MIROVA is a hot-spot detection system based on the analysis of the Moderate Resolution Imaging Spectroradiometer (MODIS) data that provide thermal maps (1 km resolution) and radiant flux estimates, in near real time (1-4 hours from satellite overpass). Thermal output retrieved by MIROVA can be converted into time-average lava discharge rates allowing the identification of ongoing effusive trends. During the first 45 days of activity the eruption shows a waxing-waning trend typical of pressurized closed systems. Preliminary results indicate that MIROVA is particularly efficient to provide near real-time data that are critical for better assessing volcanic risk, and to help the decision-makers during volcanic crisis. Data requested by the UNDAC (United Nations Disaster Assessment and Coordination) team operating in Cape Verde, through the Emergency Response Coordination Center (ERCC) of the European Mechanism of Civil Protection, were provided in near real-time via web to the National Institute of Meteorology and Geophysics and to National Civil Protection. Once compared to seismological data, information provided by MIROVA have been successfully used during the volcanic crisis.

  17. Eruption of Shiveluch Volcano, Kamchatka, Russia

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On the night of June 4, 2001 ASTER captured this thermal image of the erupting Shiveluch volcano. Located on Russia's Kamchatka Peninsula, Shiveluch rises to an altitude of 8028'. The active lava dome complex is seen as a bright (hot) area on the summit of the volcano. To the southwest, a second hot area is either a debris avalanche or hot ash deposit. Trailing to the west is a 25 km ash plume, seen as a cold 'cloud' streaming from the summit. At least 60 large eruptions have occurred during the last 10,000 years; the largest historical eruptions were in 1854 and 1964. Because Kamchatka is located along the major aircraft routes between North America/Europe and the Far East, this area is constantly monitored for potential ash hazards to aircraft. The lower image is the same as the upper, except it has been color coded: red is hot, light greens to dark green are progressively colder, and gray/black are the coldest areas.

    The image is located at 56.7 degrees north latitude, 161.3 degrees east longitude.

    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, Calif., 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 ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in

  18. Winter warming from large volcanic eruptions

    NASA Technical Reports Server (NTRS)

    Robock, Alan; Mao, Jianping

    1992-01-01

    An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95-percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

  19. Tornados and Transverse Oscillations during Prominence Eruption

    NASA Astrophysics Data System (ADS)

    Banerjee, Dipankar; Chandrashekhar, K.; Morton, Richard; Pant, Vaibhav; Datta, Ajanta

    2016-07-01

    We report and analyse different phases of a prominence eruption. The winding-unwinding of two footpoints and a tornado like swirling motion is studied. The prominence eruption is observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). This prominence eruption is associated with a CME at a central principal angle of 340 degree, according to the SOHO/LASCO CME catalogue. We can observe the prominence threads and the time distance maps reveal that the loop threads are entangled. We also study the transverse oscillations in the threads. Swirling motions after the eruptions are also quantified and its possible link with the CME kinematics is also studied

  20. Winter warming from large volcanic eruptions

    SciTech Connect

    Robock, A.; Mao, J.

    1992-01-01

    An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95 percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

  1. Abrupt transitions during sustained explosive eruptions: Examples from the 1912 eruption of Novarupta, Alaska

    USGS Publications Warehouse

    Adams, N.K.; Houghton, B.F.; Hildreth, W.

    2006-01-01

    Plinian/ignimbrite activity stopped briefly and abruptly 16 and 45 h after commencement of the 1912 Novarupta eruption defining three episodes of explosive volcanism before finally giving way after 60 h to effusion of lava domes. We focus here on the processes leading to the termination of the second and third of these three episodes. Early erupted pumice from both episodes show a very similar range in bulk vesicularity, but the modal values markedly decrease and the vesicularity range widens toward the end of Episode III. Clasts erupted at the end of each episode represent textural extremes; at the end of Episode II, clasts have very thin glass walls and a predominance of large bubbles, whereas at the end of Episode III, clasts have thick interstices and more small bubbles. Quantitatively, all clasts have very similar vesicle size distributions which show a division in the bubble population at 30 ??m vesicle diameter and cumulative number densities ranging from 107-109 cm-3. Patterns seen in histograms of volume fraction and the trends in the vesicle size data can be explained by coalescence signatures superimposed on an interval of prolonged nucleation and free growth of bubbles. Compared to experimental data for bubble growth in silicic melts, the high 1912 number densities suggest homogeneous nucleation was a significant if not dominant mechanism of bubble nucleation in the dacitic magma. The most distinct clast populations occurred toward the end of Plinian activity preceding effusive dome growth. Distributions skewed toward small sizes, thick walls, and teardrop vesicle shapes are indicative of bubble wall collapse marking maturation of the melt and onset of processes of outgassing. The data suggest that the superficially similar pauses in the 1912 eruption which marked the ends of episodes II and III had very different causes. Through Episode III, the trend in vesicle size data reflects a progressive shift in the degassing process from rapid magma ascent and

  2. Why do Martian Magmas erupt?

    NASA Astrophysics Data System (ADS)

    Balta, J. B.; McSween, H. Y.

    2011-12-01

    Eruption of silicate lava, whether on Earth or another planet, requires that at some depth the melt has lower density than the surrounding rocks. As the densities of silicate liquids change during crystallization, whether a particular silicate liquid will erupt or be trapped at a level of neutral buoyancy is a complex yet fundamental issue for planetary dynamics. In general, 3 factors drive surface eruptions: inherent buoyancy relative to mantle phases, compositional evolution, and volatile contents. These factors manifest on Earth as terrestrial basalts commonly have compositions close to a density minimum [1]. Recent work has produced estimates of Martian parental magma compositions [2-5] based on shergottite meteorites and from Gusev crater. Using the MELTS algorithm [6] and other density calibrations, we simulated evolution of these liquids, focusing on density changes. For much of the crystallization path, density is controlled by FeO. All of the liquids begin with ρ ~ 2.8 g/cc at 1 bar, and the evolution of liquid density is controlled by the liquidus phases. At low pressures, olivine is the liquidus phase for each melt, and as FeO is not incompatible in olivine, olivine crystallization decreases liquid density, increasing buoyancy with crystallization. However, FeO is incompatible in pyroxene, and thus liquids crystallizing pyroxene become denser and less buoyant with crystallization, producing liquids with densities up to and above 3.0 g/cc. As the olivine-pyroxene saturation relationship is affected by pressure and chemistry, the identity of the liquidus phase and density evolution will vary between magmas. Without spreading centers, Mars has no location where the mantle approaches the surface, and it is likely that any magma which is denser than the crust will stall below or within that crust. The crystallization path of a liquid is a function of pressure, with pyroxene crystallizing first at P > 10 kbar (~80 km depth), close to the base of the Martian

  3. Futurvolc and the Bardarbunga eruption 2014-15 Iceland, success in the field and laboratory.

    NASA Astrophysics Data System (ADS)

    Hoskuldsson, Armann; Jonsdottir, Ingibjorg; Thordarson, Thor

    2016-04-01

    The Bardarbunga volcanic system in Iceland started unrest in August 2014. Seismic activity gradually build up, until magma began to be extruded on surface. The first eruption occurred on the 28th of August and was small and subglacial, the second eruption took place outside the glacier, on the 29th of August and lasted for few hours. Third and largest eruption started on early morning 31st of August. This was to be the largest eruption in Iceland since Laki eruption 1783. The eruption used the same fissure that had opened up on the 28th but was much larger. The fissure was about 2 km long with a curtain of fire along the whole fissure, curtains reaching up to 150 m into the air. The area in which the eruption took place is a glacial river outwash plain, thus relatively flat. Although the eruption site is remote, being in the highlands north of the icecap Vatnajökull, at an average altitude of some 700 m, the flat sandur plain offered a unique opportunity to combine satellite and on site observations methods. The eruption ended on the 27th of February 2015, thus lasting for almost 6 months, during this time some 1.44 km3 of lava was erupted. From day one satellite data from NOAA AVHRR, MODIS, LANDSAT 7 and 8, ASTER, EO-1 ALI, EO-1 HYPERION, SENTINEL-1, RADARSAT-2 COSMO SKYMED and TERRASAR X where collected and used in combination with onsite observation. Resulting data give unique information on the effusion rates in basaltic fissure eruptions and its evolution with time. Further information on flow behavior and cooling of basaltic lava being emplaced in a relatively flat land can be used for future and past predictions. In this talk we shall show how valuable the combination of satellite data to field observation are to be able to precisely monitor on of the largest lava eruption on earth for the past 200 years. The role of Futurevolc and preparedness involved in that work greatly enhanced and facilitated synchronization of onsite and remote data during the

  4. Using SOHO to Understand CME-Producing Quiet-Region Filament Eruptions

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.; Moore, R. L.; Harra, L. K.

    2006-01-01

    In recent years we have been studying solar eruptions in an attempt to determine their primary initiation mechanism. We have focused on events involving filaments, because motions of the filaments just prior to their violent eruption are indicative of changes in the entire magnetic field system involved in the eruption. When the pre-eruption filament resides in a quiet region, the motions leading up to eruption are slower than in similar eruptions in active regions due to the weaker magnetic field strength and correspondingly lower Alfven velocities. These early motions manifest themselves in a slow rise (a few km/s) of the filament, in some cases lasting several hours. After this the filament and associated magnetic structures erupt rapidly, accelerating to speeds of a few 10 kmh over a few minutes. Because of their slow evolution, quiet-region eruptions such as these can be effectively studied in EUV with SOHO/EIT, with its regular cadence of about 12 min. For several cases we have combined EIT images with SOHO/MDI magnetograms and data from other other instruments, and compared our observations with predictions from various eruption scenarios, in particular the "breakout" (Antiochos 1998), "tether cutting" (e.g., Moore et al. 2001), and MHD instability mechanisms. Here we present a representative example of a quiet-region eruption involving a filament ejection, that occurred on 2001 February 28 in a magnetically quadrupolar region and produced a halo CME in SOHO/LASCO images. In addition to EIT and MDI, we analyzed spectral data from SOHO/CDS and soft X-ray (SXR) images from Yohkoh/SXT. We found that flux emergence occurred near one end of the filament, and that both this emergence and resulting microflaring in SXRs and EUV were temporally and spatially closely related to the start of the filament's slow rise. Intensity changes (dimmings and brightenings) in the EIT and SXT images indicate that fields far removed from the erupting core were involved in the

  5. Volcaniclastic stratigraphy of Gede Volcano, West Java, Indonesia: How it erupted and when

    NASA Astrophysics Data System (ADS)

    Belousov, A.; Belousova, M.; Krimer, D.; Costa, F.; Prambada, O.; Zaennudin, A.

    2015-08-01

    Gede Volcano, West Java (Indonesia), is located 60 km south of Jakarta within one of the regions with highest population density in the world. Therefore, knowledge of its eruption history is necessary for hazard evaluation, because even a small eruption would have major societal and economic consequences. Here we report the results of the investigation of the stratigraphy of Gede (with the focus on its volcaniclastic deposits of Holocene age) and include 23 new radiocarbon dates. We have found that a major part of the volcanic edifice was formed in the Pleistocene when effusions of lavas of high-silica basalt dominated. During this period the volcano experienced large-scale lateral gravitational failure followed by complete reconstruction of the edifice, formation of the summit subsidence caldera and its partial refilling. After a repose period of > 30,000 years the volcanic activity resumed at the Pleistocene/Holocene boundary. In the Holocene the eruptions were dominantly explosive with magma compositions ranging from basaltic andesite to rhyodacite; many deposits show heterogeneity at the macroscopic hand specimen scale and also in the minerals, which indicates interactions between mafic (basaltic andesite) and silicic (rhyodacite) magmas. Significant eruptions of the volcano were relatively rare and of moderate violence (the highest VEI was 3-4; the largest volume of erupted pyroclasts 0.15 km3). There were 4 major Holocene eruptive episodes ca. 10,000, 4000, 1200, and 1000 yr BP. The volcanic plumes of these eruptions were not buoyant and most of the erupted products were transported in the form of highly concentrated valley-channelized pyroclastic flows. Voluminous lahars were common in the periods between the eruptions. The recent eruptive period of the volcano started approximately 800 years ago. It is characterized by frequent and weak VEI 1-2 explosive eruptions of Vulcanian type and rare small-volume extrusions of viscous lava. We estimate that during

  6. Formation of Prominences and Dynamics Before Eruption

    NASA Astrophysics Data System (ADS)

    Luna, Manuel

    2016-07-01

    Solar prominences have fascinated to astronomers since the first scientific observations of eclipses. Prominences are spectacular manifestations of both quiescent and eruptive solar activity. These are cool and dense structures suspended in the very hot solar corona. The continuous improvements in spatial and temporal resolution from both ground- and space-based instruments have revealed a rich structure and dynamics of prominences. Despite over one century of observations, the magnetic structure of a solar prominence, the origin of its mass, and their dynamics remain vigorously debated issues with profound implications for space weather. In this talk I will address the question of the origin of the cool mass of prominences by reviewing past and recent advances in theoretical modelling.

  7. Fixed drug eruption due to levocetirizine.

    PubMed

    Jhaj, Ratinder; Asati, Dinesh Prasad; Chaudhary, Deepa

    2016-01-01

    A fixed drug eruption (FDE) is a cutaneous adverse drug reaction due to Type IV or delayed cell-mediated hypersensitivity. Antihistamines, which antagonize the action of histamine during an allergic reaction by blocking the H1 histamine receptors, are used routinely for the treatment of various allergic disorders such as urticaria, eczemas, and also in itchy lesions of skin like scabies. Levocetirizine, an active (R)-enantiomer of cetirizine, is a newer or second generation antihistamine, with more specific actions and fewer side effects, including cutaneous reactions. FDE due to levocetirizine as well as with cetirizine are rare. We report a case of levocetirizine induced FDE in a 49-year-old male patient with scabies. The patient had a history of cetirizine induced FDE in the past. PMID:27440959

  8. Fixed drug eruption due to levocetirizine

    PubMed Central

    Jhaj, Ratinder; Asati, Dinesh Prasad; Chaudhary, Deepa

    2016-01-01

    A fixed drug eruption (FDE) is a cutaneous adverse drug reaction due to Type IV or delayed cell-mediated hypersensitivity. Antihistamines, which antagonize the action of histamine during an allergic reaction by blocking the H1 histamine receptors, are used routinely for the treatment of various allergic disorders such as urticaria, eczemas, and also in itchy lesions of skin like scabies. Levocetirizine, an active (R)-enantiomer of cetirizine, is a newer or second generation antihistamine, with more specific actions and fewer side effects, including cutaneous reactions. FDE due to levocetirizine as well as with cetirizine are rare. We report a case of levocetirizine induced FDE in a 49-year-old male patient with scabies. The patient had a history of cetirizine induced FDE in the past. PMID:27440959

  9. Kamchatkan Volcanoes Explosive Eruptions in 2014 and Danger to Aviation

    NASA Astrophysics Data System (ADS)

    Girina, Olga; Manevich, Alexander; Melnikov, Dmitry; Demyanchuk, Yury; Nuzhdaev, Anton; Petrova, Elena

    2015-04-01

    There are 30 active volcanoes in the Kamchatka, and several of them are continuously active. In 2014, three of the Kamchatkan volcanoes - Sheveluch, Karymsky and Zhupanovsky - had strong and moderate explosive eruptions. Moderate gas-steam activity was observing of Klyuchevskoy, Bezymianny, Avachinsky, Koryaksky, Gorely, Mutnovsky and other volcanoes. Strong explosive eruption of volcanoes is the most dangerous for aircraft because in a few hours or days in the atmosphere and the stratosphere can produce about several cubic kilometers of volcanic ash and aerosols. Ash plumes and the clouds, depending on the power of the eruption, the strength and wind speed, can travel thousands of kilometers from the volcano for several days, remaining hazardous to aircraft, as the melting temperature of small particles of ash below the operating temperature of jet engines. The eruptive activity of Sheveluch Volcano began since 1980 (growth of the lava dome) and is continuing at present. Strong explosive events of the volcano occurred in 2014: on January 08 and 12, May 12, September 24, October 02 and 28, November 16, 22 and 26, and December 05, 17, 26 and 29: ash plumes rose up to 9-12 km a.s.l. and extended more 900 km to the eastern and western directions of the volcano. Ashfalls occurred at Klyuchi Village (on January 12, June 11, and November 16). Activity of the volcano was dangerous to international and local aviation. Karymsky volcano has been in a state of explosive eruption since 1996. The moderate ash explosions of this volcano were noting during 2014: from March 24 till April 02; and from September 03 till December 10. Ash plumes rose up to 5 km a.s.l. and extended more 300 km mainly to the eastern directions of the volcano. Activity of the volcano was dangerous to local aviation. Explosive eruption of Zhupanovsky volcano began on June 06, 2014 and continues in January 2015 too. Ash explosions rose up to 8-10 km a.s.l. on June 19, September 05 and 07, October 11

  10. The 2011 Cerro Hudson volcano eruption (Southern Andes, Chile): Pre-eruptive inflation and hot spots observed with InSAR and thermal imagery

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Pritchard, M. E.; Lohman, R. B.

    2013-12-01

    Cerro Hudson is one of most active volcanoes of the Southern Andes with at least 12 documented Holocene eruptions including two large caldera forming eruptions (VEI>6) at 6700 and 3600 years BP and one of the largest eruptions of the 20th century in 1991 -- VEI of 5 and ~2.7 km3 of dense rock equivalent erupted material. The volcano had smaller eruptions in 1971 (VEI 3) and 2011 (VEI of 1-2), but despite its persistent activity, there is little monitoring because of its remote location. In this work we focus on remote sensing observations to better characterize the activity of Cerro Hudson between the 1991 and 2011 eruptions and during the 2011 eruption. Our primary technique is satellite-based interferometric synthetic aperture radar (InSAR). Although InSAR studies at Cerro Hudson are challenging given the poor data coverage as well as the presence of ice, snow and vegetation, the data show that the volcano inflated between 2004 and 2010 with a maximum range change rate between 2 and 3 cm/yr, about half of the deformation rate observed during a previously detected deformation episode from 1993-1999. Inversion for an inflating point source suggests magma accumulation beneath the SW part of the caldera at an average depth of 10 km -- deeper than the depths estimated for the magma chamber of the 1991 eruption (3 km) and a deformation event between 1993 and 1999 (5-6 km), and in a slightly different location with smaller volume changes. The center of deformation is located a few km away from the eruption location near the caldera ring fault, but the predicted static Coloumb stress changes due to the inferred inflation source would enhance motion on the caldera ring fault, suggesting that the deformation and eruptive vents may be linked. We also analize nighttime satellite thermal images from MODIS and ASTER for pixel-integrated temperatures above the background temperatures in the ice filled caldera. While MODIS did not show any unambiguous evidence for the eruption

  11. What Generated the Eruptive Tremor During the Bardarbunga Eruption, Iceland?

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristin S.; Jónsdóttir, Ingibjörg; Höskuldsson, Armann; Þórðarson, Þorvaldur

    2016-04-01

    The Bárðarbunga eruption in Iceland 2014/15 led to the formation of a 85 km2 big lavafield and the extrusion of ~1.5 km3 of magma. The eruption initially started for 4 hours on August 29th. It stopped but restarted on the same fissure on August 31st. We installed a seismic array on August 30th. Harmonic tremor was seen on August 31st consistent with the visual opening of the fissure and continued through February 2015. The harmonic tremor with most energy from 0.8-1.5 Hz is remarkably stable over 6 months but 3 characteristic features occur from time to time: (i) Stronger harmonic tremor bursts in the same frequency range, (ii) Stronger non-harmonic bursts with energy up to 5 Hz and (iii) Step like increases or decreases in the tremor amplitude. Seemingly uncorrelated the array results show (iv) three very stable tremor directions until mid October and (v) tremor sources moving by up to 9 km in 4 days. We compare these five seismic observations with the features of the growing lavafield and discuss the relative importance of possible tremor sources such as: a resonating conduit, boiling magma in the vent, a resonating lavafield, interactions at the edges of the lavafield and inflation of the lavafield.

  12. RECURRENT EXPLOSIVE ERUPTIONS AND THE ''SIGMOID-TO-ARCADE'' TRANSFORMATION IN THE SUN DRIVEN BY DYNAMICAL MAGNETIC FLUX EMERGENCE

    SciTech Connect

    Archontis, V.; Hood, A. W.; Tsinganos, K.

    2014-05-10

    We report on three-dimensional MHD simulations of recurrent mini coronal mass ejection (CME)-like eruptions in a small active region (AR), which is formed by the dynamical emergence of a twisted (not kink unstable) flux tube from the solar interior. The eruptions develop as a result of the repeated formation and expulsion of new flux ropes due to continuous emergence and reconnection of sheared field lines along the polarity inversion line of the AR. The acceleration of the eruptions is triggered by tether-cutting reconnection at the current sheet underneath the erupting field. We find that each explosive eruption is followed by reformation of a sigmoidal structure and a subsequent ''sigmoid-to-flare arcade'' transformation in the AR. These results might have implications for recurrent CMEs and eruptive sigmoids/flares observations and theoretical studies.

  13. Volcanic geology and eruption frequency, lower east rift zone of Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Moore, R.B.

    1992-01-01

    Detailed geologic mapping and radiocarbon dating of tholeiitic basalts covering about 275 km2 on the lower east rift zone (LERZ) and adjoining flanks of Kilauea volcano, Hawaii, show that at least 112 separate eruptions have occurred during the past 2360 years. Eruptive products include spatter ramparts and cones, a shield, two extensive lithic-rich tuff deposits, aa and pahoehoe flows, and three littoral cones. Areal coverage, number of eruptions and average dormant interval estimates in years for the five age groups assigned are: (I) historic, i.e. A D 1790 and younger: 25%, 5, 42.75; (II) 200-400 years old: 50%, 15, 14.3: (III) 400-750 years old: 20%, 54, 6.6; (IV) 750-1500 years old: 5%, 37, 20.8; (V) 1500-3000 years old: <1%, 1, unknown. At least 4.5-6 km3 of tholeiitic basalt have been erupted from the LERZ during the past 1500 years. Estimated volumes of the exposed products of individual eruptions range from a few tens of cubic meters for older units in small kipukas to as much as 0.