Sample records for africa began erupting

  1. Tropical explosive volcanic eruptions can trigger El Niño by cooling tropical Africa.

    PubMed

    Khodri, Myriam; Izumo, Takeshi; Vialard, Jérôme; Janicot, Serge; Cassou, Christophe; Lengaigne, Matthieu; Mignot, Juliette; Gastineau, Guillaume; Guilyardi, Eric; Lebas, Nicolas; Robock, Alan; McPhaden, Michael J

    2017-10-03

    Stratospheric aerosols from large tropical explosive volcanic eruptions backscatter shortwave radiation and reduce the global mean surface temperature. Observations suggest that they also favour an El Niño within 2 years following the eruption. Modelling studies have, however, so far reached no consensus on either the sign or physical mechanism of El Niño response to volcanism. Here we show that an El Niño tends to peak during the year following large eruptions in simulations of the Fifth Coupled Model Intercomparison Project (CMIP5). Targeted climate model simulations further emphasize that Pinatubo-like eruptions tend to shorten La Niñas, lengthen El Niños and induce anomalous warming when occurring during neutral states. Volcanically induced cooling in tropical Africa weakens the West African monsoon, and the resulting atmospheric Kelvin wave drives equatorial westerly wind anomalies over the western Pacific. This wind anomaly is further amplified by air-sea interactions in the Pacific, favouring an El Niño-like response.El Niño tends to follow 2 years after volcanic eruptions, but the physical mechanism behind this phenomenon is unclear. Here the authors use model simulations to show that a Pinatubo-like eruption cools tropical Africa and drives westerly wind anomalies in the Pacific favouring an El Niño response.

  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. 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.

  4. Deformation associated with the 2015 Eruption of Axial Seamount

    NASA Astrophysics Data System (ADS)

    Nooner, S. L.; Chadwick, W.; Caress, D. W.; Clague, D. A.; Paduan, J. B.; Yoerger, D.; Sasagawa, G. S.

    2015-12-01

    On April 24th 2015, an eruption began at Axial Seamount, a seafloor volcano located about 480 km west of the Oregon coast at the intersection of the Cobb hotspot and the Juan de Fuca Ridge. This eruption was first detected in real time by the newly operational Ocean Observatories Initiative cabled instrumentation at Axial (Delaney, AGU-2015, Wilcock, AGU-2015, Caplan-Auerbach, AGU-2015). Two prior eruptions have been observed since routine observations began in the 1990's, one in January 1998 and the other in April 2011. Precise water pressure measurements made on the volcano have documented an inflation/deflation cycle within Axial's summit caldera for the past 15 years. These data are now being supplemented by repeat bathymetric mapping by AUV. The long-term pattern appears to be "inflation predictable", in which eruptions are triggered at or near the same level of inflation. This pattern allowed us to successfully forecast in September 2014 that the next eruption was expected to occur at Axial sometime in 2015 (a 1-year time window). It is noteworthy that the rate of inflation between the 2011 and 2015 eruptions was about 4 times higher than between the 1998 and 2011 eruptions (60 cm/yr vs. 15 cm/yr). Subsidence at the caldera center began at 06:00 on 24 April (all times GMT) and amounted to 2.2 m by 02:00 on 25 April (20 hours in), 2.4 m by 00:00 on 28 April, and 2.45 m by 05 May when subsidence ended and re-inflation began (which has continued ever since). This amount of subsidence is similar to that observed during the 2011 eruption, but in 2015 the initial rate of subsidence was higher (11 cm/hr during the first 20 hours vs. 7 cm/hr in 2011) and the duration appears to have been longer (11 days vs. 6 days). Also, the 1998 and 2011 eruptions occurred along the southeastern edge of the caldera and along Axial's south rift zone, whereas the 2015 eruption occurred along the north rift zone (Kelley, AGU-2015). Here we present preliminary results of our August

  5. Monitoring a restless volcano: The 2004 eruption of Mount St. Helens

    USGS Publications Warehouse

    Gardner, C.

    2005-01-01

    Although the precise course of volcanic activity is difficult to predict, volcanologists are pretty adept at interpreting volcanic signals from well-monitored volcanoes in order to make short-term forecasts. Various monitoring tools record effects to give us warning before eruptions, changes in eruptive behavior during eruptions, or signals that an eruption is ending. Foremost among these tools is seismic monitoring. The character, size, depth and rate of earthquakes are all important to the interpretation of what is happening belowground. The first inkling of renewed activity at Mount St. Helens began in the early hours of Sept. 23, when a seismic swarm - tens to hundreds of earthquakes over days to a week - began beneath the volcano. This article details the obervations made during the eruptive sequence.

  6. 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

  7. Interdisciplinary studies of eruption at Chaiten Volcano, Chile

    Treesearch

    John S. Pallister; Jon J. Major; Thomas C. Pierson; Richard P. Hoblitt; Jacob B. Lowenstern; John C. Eichelberger; Lara Luis; Hugo Moreno; Jorge Munoz; Jonathan M. Castro; Andres Iroume; Andrea Andreoli; Julia Jones; Fred Swanson; Charlie Crisafulli

    2010-01-01

    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 Chaiten volcano, southern Chile, a 3-kilometer-diameter caldera volcano with a prehistoric record of rhyolite eruptions. Vigorous explosions occurred through 8 May 2008, after which...

  8. NASA Spacecraft Images Mexican Volcanic Eruption

    NASA Image and Video Library

    2012-04-24

    NASA Terra spacecraft shows Mexico active Popocatepetl volcano, located about 40 miles southeast of Mexico City, spewing water vapor, gas, ashes and glowing rocks since its most recent eruption period began in April 2012.

  9. Humans thrived in South Africa through the Toba eruption about 74,000 years ago

    NASA Astrophysics Data System (ADS)

    Smith, Eugene I.; Jacobs, Zenobia; Johnsen, Racheal; Ren, Minghua; Fisher, Erich C.; Oestmo, Simen; Wilkins, Jayne; Harris, Jacob A.; Karkanas, Panagiotis; Fitch, Shelby; Ciravolo, Amber; Keenan, Deborah; Cleghorn, Naomi; Lane, Christine S.; Matthews, Thalassa; Marean, Curtis W.

    2018-03-01

    Approximately 74 thousand years ago (ka), the Toba caldera erupted in Sumatra. Since the magnitude of this eruption was first established, its effects on climate, environment and humans have been debated. Here we describe the discovery of microscopic glass shards characteristic of the Youngest Toba Tuff—ashfall from the Toba eruption—in two archaeological sites on the south coast of South Africa, a region in which there is evidence for early human behavioural complexity. An independently derived dating model supports a date of approximately 74 ka for the sediments containing the Youngest Toba Tuff glass shards. By defining the input of shards at both sites, which are located nine kilometres apart, we are able to establish a close temporal correlation between them. Our high-resolution excavation and sampling technique enable exact comparisons between the input of Youngest Toba Tuff glass shards and the evidence for human occupation. Humans in this region thrived through the Toba event and the ensuing full glacial conditions, perhaps as a combined result of the uniquely rich resource base of the region and fully evolved modern human adaptation.

  10. Detailed View of Erupting Nabro Volcano

    NASA Image and Video Library

    2011-06-28

    NASA image acquired June 24, 2011 Since it began erupting on June 12, 2011, emissions from Eritrea’s Nabro Volcano have drifted over much of East Africa and the Middle East. Ash has displaced residents living near the volcano and disrupted flights in the region. Despite the volcano’s widespread effects, little is known about the eruption. Nabro is located in an isolated region along the border between Eritrea and Ethiopia, and few English-language reports have been published. Satellite remote sensing is currently the only reliable way to monitor the ongoing eruption. This satellite image is among the first detailed pictures of the erupting vent and lava flows. They were acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite on June 24, 2011. The bright red portions of the false-color image (top) indicate hot surfaces. Hot volcanic ash glows above the vent, located in the center of Nabro’s caldera. To the west of the vent, portions of an active lava flow (particularly the front of the flow) are also hot. The speckled pattern on upstream portions of the flow are likely due to the cool, hardened crust splitting and exposing fluid lava as the flow advances. The bulbous blue-white cloud near the vent is likely composed largely of escaping water vapor that condensed as the plume rose and cooled. The whispy, cyan clouds above the lava flow are evidence of degassing from the lava. NASA Earth Observatory image by Robert Simmon, using EO-1 ALI data. Caption by Robert Simmon. Instrument: EO-1 - ALI To download the high res go here: earthobservatory.nasa.gov/IOTD/view.php?id=51216 NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on

  11. Rapid laccolith intrusion driven by explosive volcanic eruption

    NASA Astrophysics Data System (ADS)

    Castro, Jonathan M.; Cordonnier, Benoit; Schipper, C. Ian; Tuffen, Hugh; Baumann, Tobias S.; Feisel, Yves

    2016-11-01

    Magmatic intrusions and volcanic eruptions are intimately related phenomena. Shallow magma intrusion builds subsurface reservoirs that are drained by volcanic eruptions. Thus, the long-held view is that intrusions must precede and feed eruptions. Here we show that explosive eruptions can also cause magma intrusion. We provide an account of a rapidly emplaced laccolith during the 2011 rhyolite eruption of Cordón Caulle, Chile. Remote sensing indicates that an intrusion began after eruption onset and caused severe (>200 m) uplift over 1 month. Digital terrain models resolve a laccolith-shaped body ~0.8 km3. Deformation and conduit flow models indicate laccolith depths of only ~20-200 m and overpressures (~1-10 MPa) that likely stemmed from conduit blockage. Our results show that explosive eruptions may rapidly force significant quantities of magma in the crust to build laccoliths. These iconic intrusions can thus be interpreted as eruptive features that pose unique and previously unrecognized volcanic hazards.

  12. Rapid laccolith intrusion driven by explosive volcanic eruption.

    PubMed

    Castro, Jonathan M; Cordonnier, Benoit; Schipper, C Ian; Tuffen, Hugh; Baumann, Tobias S; Feisel, Yves

    2016-11-23

    Magmatic intrusions and volcanic eruptions are intimately related phenomena. Shallow magma intrusion builds subsurface reservoirs that are drained by volcanic eruptions. Thus, the long-held view is that intrusions must precede and feed eruptions. Here we show that explosive eruptions can also cause magma intrusion. We provide an account of a rapidly emplaced laccolith during the 2011 rhyolite eruption of Cordón Caulle, Chile. Remote sensing indicates that an intrusion began after eruption onset and caused severe (>200 m) uplift over 1 month. Digital terrain models resolve a laccolith-shaped body ∼0.8 km 3 . Deformation and conduit flow models indicate laccolith depths of only ∼20-200 m and overpressures (∼1-10 MPa) that likely stemmed from conduit blockage. Our results show that explosive eruptions may rapidly force significant quantities of magma in the crust to build laccoliths. These iconic intrusions can thus be interpreted as eruptive features that pose unique and previously unrecognized volcanic hazards.

  13. Mount St. Helens: Still erupting lessons 31 years later

    Treesearch

    Rhonda Mazza; Charlie Crisafulli; Fred Swanson

    2011-01-01

    The massive volcanic eruption of Mount St. Helens 31 years ago provided the perfect backdrop for studying the earliest stages of forest development. Immediately after the eruption, some areas of the blast area were devoid of life. On other parts of the volcanic landscape, many species survived, although their numbers were greatly reduced. Reassembly began at many...

  14. Multidisciplinary Studies of the 2015-2016 Eruption of Momotombo Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Roman, D. C.; La Femina, P. C.; Connor, C.; Connor, L.; Dixon, T. H.; Feineman, M. D.; Gallant, E.; Geirsson, H.; Glover, C.; Rinehart, J. M.; Ruiz, G.; Saballos, A.; Strauch, W.; Tenorio, V.; Wauthier, C.; Webley, P. W.; Wnuk, K.

    2016-12-01

    Momotombo volcano, Nicaragua, began erupting in December 2015 after 105 years of dormancy. Within weeks of the eruption onset, an international team of scientists began interdisciplinary studies investigating the geophysical and geochemical processes of the eruption. Our work included the installation of new seismic and geodetic networks, sampling of lava flows and ashes for geochemical and petrographic analyses, and the collection and analysis of space and ground-based radar data. Momotombo volcano has been seismically restless since at least the 1980's, when modern records are first available. Beginning in September 2013, discrete seismic swarms including events up to M4 and depths of 20 km occurred periodically. On April 10, 2014 an M6.1 earthquake occurred in Lake Managua displacing the southern flank of the volcano more than 5 cm as measured at a continuous GPS (cGPS) site. A major seismic swarm, which included an M4.7 earthquake, began on November 24, 2015, and culminated in gas and ash eruptions beginning at 7:49 am (local time) on December 1, 2015. By the evening of December 1, Momotombo was in strombolian eruption with columns to 1 km and a lava flow advancing down the northern flank. To date, there have been over 435 explosions as detected by seismic data and visually on webcam imagery, with the last explosion on April 7, 2016. Utilizing cGPS and episodic GPS observations and radar interferometry (InSAR), we did not detect any significant pre-, co-, or post-eruptive magmatic deformation. Lava samples collected from the 2015, 1905, and pre-1905 eruptions are all basaltic andesites with nearly identical major and trace element compositions, suggesting a long-lived magma body. Concentrations of metals and volatiles in ash leachates decrease over time in the first two days of the eruption. Our interdisciplinary studies allow for an integrated analysis of this strombolian eruption and its hazards.

  15. Explosive eruption records from Eastern Africa: filling in the gaps with tephra records from stratified lake sequences

    NASA Astrophysics Data System (ADS)

    Lane, Christine; Asrat, Asfawossen; Cohen, Andy; Cullen, Victoria; Johnson, Thomas; Lamb, Henry; Martin-Jones, Catherine; Poppe, Sam; Schaebitz, Frank; Scholz, Christopher

    2017-04-01

    On-going research into the preservation of volcanic ash fall in stratified Holocene lake sediments in Eastern Africa reveals the level of incompleteness of our explosive eruption record. Only nine eruptions with VEI >4 are recorded in the LaMEVE database (Crosweller et al., 2012) and of the 188 Holocene eruptions listed for East African volcanoes in the Global Volcanism Programme database, only 24 are dated to > 2000 years ago (GVP, 2013). Tephrostratigraphic investigation of Holocene sediments from a number of lakes, including Lake Kivu (south of the Virunga volcanic field), Lake Victoria (west of the Kenyan Rift volcanism) and palaeolake Chew Bahir (southern Ethiopia), all reveal multiple tephra layers, which indicate vastly underestimated eruption histories. Whereas the tephra layers in Lake Kivu were all located macroscopically, no visible tephra layers were observed in the sediments from Lake Victoria and Chew Bahir. Instead, tephra are preserved as non-visible horizons (cryptotephra), revealed only after laboratory processing. These results indicate that even where we do have stratified visible tephra records, the number of past eruptions may still be a minimum. Cryptotephra studies therefore play a fundamental role in building comprehensive records of past volcanism. Challenges remain, in this understudied region, to identify the volcanic source of each of the tephra layers, which requires geochemical correlation to proximal volcanic deposits. Where correlations to source can be achieved, explosive eruption frequencies and recurrence rates may be assessed for individual volcanoes. Furthermore, if a tephra layer can be traced into multiple sedimentary sequences, the potential exists to evaluate eruption magnitude, providing a more useful criterion for risk assessment. Filling in the gaps in our understanding of East African Rift volcanism and the associated hazards is therefore critically dependent upon bringing together this important data from distal

  16. Ionospheric "Volcanology": Ionospheric Detection of Volcano Eruptions

    NASA Astrophysics Data System (ADS)

    Astafyeva, E.; Shults, K.; Lognonne, P. H.; Rakoto, V.

    2016-12-01

    It is known that volcano eruptions and explosions can generate acoustic and gravity waves. These neutral waves further propagate into the atmosphere and ionosphere, where they are detectable by atmospheric and ionospheric sounding tools. So far, the features of co-volcanic ionospheric perturbations are not well understood yet. The development of the global and regional networks of ground-based GPS/GNSS receivers has opened a new era in the ionospheric detection of natural hazard events, including volcano eruptions. It is now known that eruptions with the volcanic explosivity index (VEI) of more than 2 can be detected in the ionosphere, especially in regions with dense GPS/GNSS-receiver coverage. The co-volcanic ionospheric disturbances are usually characterized as quasi-periodic oscillations. The Calbuco volcano, located in southern Chile, awoke in April 2015 after 43 years of inactivity. The first eruption began at 21:04UT on 22 April 2015, preceded by only an hour-long period of volcano-tectonic activity. This first eruption lasted 90 minutes and generated a sub-Plinian (i.e. medium to large explosive event), gray ash plume that rose 15 km above the main crater. A larger second event on 23 April began at 04:00UT (01:00LT), it lasted six hours, and also generated a sub-Plinian ash plume that rose higher than 15 km. The VEI was estimated to be 4 to 5 for these two events. In this work, we first study ionospheric TEC response to the Calbuco volcano eruptions of April 2015 by using ground-based GNSS-receivers located around the volcano. We analyze the spectral characteristics of the observed TEC variations and we estimate the propagation speed of the co-volcanic ionospheric perturbations. We further proceed with the normal mode summation technique based modeling of the ionospheric TEC variations due to the Calbuco volcano eruptions. Finally, we attempt to localize the position of the volcano from the ionospheric measurements, and we also estimate the time of the

  17. Modelling fluid flow in clastic eruptions: application to the Lusi mud eruption.

    NASA Astrophysics Data System (ADS)

    Collignon, Marine; Schmid, Daniel W.; Galerne, Christophe; Lupi, Matteo; Mazzini, Adriano

    2017-04-01

    Clastic eruptions involve the rapid ascension of clasts together with fluids, gas and/or liquid phases that may deform and brecciate the host rocks. These fluids transport the resulting mixture, called mud breccia, to the surface. Such eruptions are often associated with geological structures such as mud volcanoes, hydrothermal vent complexes and more generally piercement structures. They involve various processes, acting over a wide range of scales which makes them a complex and challenging, multi-phase system to model. Although piercement structures have been widely studied and discussed, only few attempts have been made to model the dynamics of such clastic eruptions. The ongoing Lusi mud eruption, in the East Java back-arc basin, which began in May 2006, is probably the most spectacular clastic eruption. Lusi's eruptive behaviour has been extensively studied over the past decade and thus represents a unique opportunity to better understand the dynamics driving clastic eruptions, including fossil clastic systems. We use both analytical formulations and numerical models to simulate Lusi's eruptive dynamics and to investigate simple relationships between the mud breccia properties (density, viscosity, gas and clast content) and the volumetric flow rate. Our results show that the conduit radius of such piercement system cannot exceeds a few meters at depth, and that clasts, if not densely packed, will not affect the flow rate when they are smaller than a fifth of the conduit size. Using published data for the annual gas fluxes at Lusi, we infer a maximal depth at which exsolution starts. This occurs between 1800 m and 3200 m deep for the methane and between 750 m and 1000 m for the carbon dioxide.

  18. Detailed View of Erupting Nabro Volcano [annotated

    NASA Image and Video Library

    2017-12-08

    NASA image acquired June 24, 2011 Since it began erupting on June 12, 2011, emissions from Eritrea’s Nabro Volcano have drifted over much of East Africa and the Middle East. Ash has displaced residents living near the volcano and disrupted flights in the region. Despite the volcano’s widespread effects, little is known about the eruption. Nabro is located in an isolated region along the border between Eritrea and Ethiopia, and few English-language reports have been published. Satellite remote sensing is currently the only reliable way to monitor the ongoing eruption. This satellite image is among the first detailed pictures of the erupting vent and lava flows. They were acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite on June 24, 2011. The bright red portions of the false-color image (top) indicate hot surfaces. Hot volcanic ash glows above the vent, located in the center of Nabro’s caldera. To the west of the vent, portions of an active lava flow (particularly the front of the flow) are also hot. The speckled pattern on upstream portions of the flow are likely due to the cool, hardened crust splitting and exposing fluid lava as the flow advances. The bulbous blue-white cloud near the vent is likely composed largely of escaping water vapor that condensed as the plume rose and cooled. The whispy, cyan clouds above the lava flow are evidence of degassing from the lava. NASA Earth Observatory image by Robert Simmon, using EO-1 ALI data. Caption by Robert Simmon. Instrument: EO-1 - ALI To download the high res go here: earthobservatory.nasa.gov/IOTD/view.php?id=51216 NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on

  19. Forecasting eruptions of Mauna Loa Volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Decker, Robert W.; Klein, Fred W.; Okamura, Arnold T.; Okubo, Paul G.

    Past eruption patterns and various kinds of precursors are the two basic ingredients of eruption forecasts. The 39 historical eruptions of Mauna Loa from 1832 to 1984 have intervals as short as 104 days and as long as 9,165 days between the beginning of an eruption and the beginning of the next one. These recurrence times roughly fit a Poisson distribution pattern with a mean recurrence time of 1,459 days, yielding a probability of 22% (P=.22) for an eruption of Mauna Loa during any next year. The long recurrence times since 1950, however, suggest that the probability is not random, and that the current probability for an eruption during the next year may be as low as 6%. Seismicity beneath Mauna Loa increased for about two years prior to the 1975 and 1984 eruptions. Inflation of the summit area took place between eruptions with the highest rates occurring for a year or two before and after the 1975 and 1984 eruptions. Volcanic tremor beneath Mauna Loa began 51 minutes prior to the 1975 eruption and 115 minutes prior to the 1984 eruption. Eruption forecasts were published in 1975, 1976, and 1983. The 1975 and 1983 forecasts, though vaguely worded, were qualitatively correct regarding the timing of the next eruption. The 1976 forecast was more quantitative; it was wrong on timing but accurate on forecasting the location of the 1984 eruption. This paper urges that future forecasts be specific so they can be evaluated quantitatively.

  20. The 1991 eruptions of Mount Pinatubo, Philippines

    USGS Publications Warehouse

    Wolfe, Edward W.

    1992-01-01

    Recognition of the volcanic unrest at Mount Pinatubo in the Philippines began when steam explosions occurred on April 2, 1991. The unrest culminated ten weeks later in the world's largest eruption in more than half a century. 

  1. Diverse Eruptive Activity Revealed by Acoustic and Electromagnetic Observations of the 14 July 2013 Intense Vulcanian Eruption of Tungurahua Volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Anderson, J. F.; Johnson, J. B.; Steele, A. L.; Ruiz, M. C.; Brand, B. D.

    2018-04-01

    During the powerful July 2013 eruption of Tungurahua volcano, Ecuador, we recorded exceptionally high amplitude, long-period infrasound (1,600-Pa peak-to-peak amplitude, 5.5-s period) on sensors within 2 km of the vent alongside electromagnetic signals from volcanic lightning serendipitously captured as interference. This explosion was one of Tungurahua's most powerful vulcanian eruptions since recent activity began in 1999, and its acoustic wave is among the most powerful volcanic infrasound ever recorded anywhere. We use these data to quantify erupted volume from the main explosion and to classify postexplosive degassing into distinct emission styles. Additionally, we demonstrate a highly effective method of recording lightning-related electromagnetic signals alongside infrasound. Detailed chronologies of powerful vulcanian eruptions are rare; this study demonstrates that diverse eruptive processes can occur in such eruptions and that near-vent infrasound and electromagnetic data can elucidate them.

  2. Rapid laccolith intrusion driven by explosive volcanic eruption

    PubMed Central

    Castro, Jonathan M.; Cordonnier, Benoit; Schipper, C. Ian; Tuffen, Hugh; Baumann, Tobias S.; Feisel, Yves

    2016-01-01

    Magmatic intrusions and volcanic eruptions are intimately related phenomena. Shallow magma intrusion builds subsurface reservoirs that are drained by volcanic eruptions. Thus, the long-held view is that intrusions must precede and feed eruptions. Here we show that explosive eruptions can also cause magma intrusion. We provide an account of a rapidly emplaced laccolith during the 2011 rhyolite eruption of Cordón Caulle, Chile. Remote sensing indicates that an intrusion began after eruption onset and caused severe (>200 m) uplift over 1 month. Digital terrain models resolve a laccolith-shaped body ∼0.8 km3. Deformation and conduit flow models indicate laccolith depths of only ∼20–200 m and overpressures (∼1–10 MPa) that likely stemmed from conduit blockage. Our results show that explosive eruptions may rapidly force significant quantities of magma in the crust to build laccoliths. These iconic intrusions can thus be interpreted as eruptive features that pose unique and previously unrecognized volcanic hazards. PMID:27876800

  3. The first five years of Kīlauea’s summit eruption in Halema‘uma‘u Crater, 2008–2013

    USGS Publications Warehouse

    Patrick, Matthew R.; Orr, Tim R.; Sutton, A.J.; Elias, Tamar; Swanson, Donald A.

    2013-01-01

    The eruption in Halema‘uma‘u Crater that began in March 2008 is the longest summit eruption of Kīlauea Volcano, on the Island of Hawai‘i, since 1924. From the time the eruption began, the new "Overlook crater" inside Halema‘uma‘u has exhibited fluctuating lava lake activity, occasional small explosive events, and a persistent gas plume. The beautiful nighttime glow impresses and thrills visitors in Hawai‘i Volcanoes National Park, but the continuous emission of sulfur dioxide gas produces "vog" (volcanic smog) that can severely affect communities and local agriculture downwind. U.S. Geological Survey scientists continue to closely monitor the eruption and assess ongoing hazards.

  4. Asymptomatic petechial eruption on the lower legs.

    PubMed

    Mendese, Gary; Grande, Donald

    2013-09-01

    The authors report an unusual case of Rocky Mountain spotted fever that presented as an asymptomatic petechial eruption on the lower legs. Rocky Mountain spotted fever is rare in New England and, as such, is typically not on the differential diagnosis when presented with such patients. What began as an asymptomatic eruption progressed to more classic signs of the disease, including a positive Rocky Mountain spotted fever titer. The patient was successfully treated with doxycydine and within a short period of time, was completely back at baseline.

  5. Eruption prediction aided by electronic tiltmeter data at Mount St. Helens

    USGS Publications Warehouse

    Dzurisin, D.; Westphal, J.A.; Johnson, Daniel J.

    1983-01-01

    Telemetry from electronic tiltmeters in the crater at Mount St. Helens contributed to accurate predictions of all six effusive eruptions from June 1981 to August 1982. Tilting of the crater floor began several weeks before each eruption, accelerated sharply for several days, and then abruptly changed direction a few minutes to days before extrusion began. Each episode of uplift was caused by the intrusion of magma into the lava dome from a shallow source, causing the dome to inflate and eventually rupture. Release of magma pressure and increased surface loading by magma added to the dome combined to cause subsidence just prior to extrusion.

  6. Eruption prediction aided by electronic tiltmeter data at mount st. Helens.

    PubMed

    Dzurisin, D; Westphal, J A; Johnson, D J

    1983-09-30

    Telemetry from electronic tiltmeters in the crater at Mount St. Helens contributed to accurate predictions of all six effusive eruptions from June 1981 to August 1982. Tilting of the crater floor began several weeks before each eruption, accelerated sharply for several days, and then abruptly changed direction a few minutes to days before extrusion began. Each episode of uplift was caused by the intrusion of magma into the lava dome from a shallow source, causing the dome to inflate and eventually rupture. Release of magma pressure and increased surface loading by magma added to the dome combined to cause subsidence just prior to extrusion.

  7. 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.

  8. Asymptomatic Petechial Eruption on the Lower Legs

    PubMed Central

    Grande, Donald

    2013-01-01

    The authors report an unusual case of Rocky Mountain spotted fever that presented as an asymptomatic petechial eruption on the lower legs. Rocky Mountain spotted fever is rare in New England and, as such, is typically not on the differential diagnosis when presented with such patients. What began as an asymptomatic eruption progressed to more classic signs of the disease, including a positive Rocky Mountain spotted fever titer. The patient was successfully treated with doxycydine and within a short period of time, was completely back at baseline. PMID:24062875

  9. NASA Satellite Tracks Underwater Volcanic Eruption in Canary Islands

    NASA Image and Video Library

    2011-11-02

    In July 2011, volcanic tremors began on the Island of El Hierro in the Canary Islands; by September, many tourists evacuated the resort island, fearing a volcanic eruption. This image is from NASA Terra spacecraft.

  10. The Ottaviano eruption of Somma-Vesuvio (8000 y B.P.): a magmatic alternating fall and flow-forming eruption

    NASA Astrophysics Data System (ADS)

    Rolandi, G.; Maraffi, S.; Petrosino, P.; Lirer, L.

    1993-11-01

    The Ottaviano eruption occurred in the late neolithic (8000 y B.P.). 2.40 km 3 of phonolitic pyroclastic material (0.61 km 3 DRE) were emplaced as pyroclastic flow, surge and fall deposits. The eruption began with a fall phase, with a model column height of 14 km, producing a pumice fall deposit (LA). This phase ended with short-lived weak explosive activity, giving rise to a fine-grained deposit (L1), passing to pumice fall deposits as the result of an increasing column height and mass discharge rate. The subsequent two fall phases (producing LB and LC deposits), had model column heights of 20 and 22 km with eruption rates of 2.5 × 10 7 and 2.81 × 10 7 kg/s, respectively. These phases ended with the deposition of ash layers (L2 and L3), related to a decreasing, pulsing explosive activity. The values of dynamic parameters calculated for the eruption classify it as a sub-plinian event. Each fall phase was characterized by variations in the eruptive intensity, and several pyroclastic flows were emplaced (F1 to F3). Alternating pumice and ash fall beds record the waning of the eruption. Finally, owing to the collapse of a eruptive column of low gas content, the last pyroclastic flow (F4) was emplaced.

  11. Episode 49 of the Pu'u 'O'o-Kupaianaha eruption of Kilauea volcano - breakdown of a steady-state eruptive era

    NASA Astrophysics Data System (ADS)

    Mangan, M. T.; Heliker, C. C.; Mattox, T. N.; Kauahikaua, J. P.; Helz, R. T.

    1995-04-01

    The Pu'u 'O'o-Kupaianaha eruption (1983-present) is the longest lived rift eruption of either Kilauea or neighboring Mauna Loa in recorded history. The initial fissure opening in January 1983 was followed by three years of episodic fire fountaining at the Pu'u 'O'o vent on Kilauea's east rift zone ˜19km from the summit (episodes 4 47). These spectacular events gave way in July 1986 to five and a half years of nearcontinuous, low-level effusion from the Kupaianaha vent, ˜ 3km to the cast (episode 48). A 49th episode began in November 1991 with the opening of a new fissure between Pu'u 'O'o and Kupaianaha. this three week long outburst heralded an era of more erratic eruptive behavior characterized by the shut down of Kupaianaha in February 1992 and subsequent intermittent eruption from vents on the west flank of Pu'u 'O'o (episodes 50 and 51). The events occurring over this period are due to progressive shrinkage of the rift-zone reservoir beneath the eruption site, and had limited impact on eruption temperatures and lava composition.

  12. Pre-, Syn- and Post Eruptive Seismicity of the 2011 Eruption of Nabro Volcano, Eritrea

    NASA Astrophysics Data System (ADS)

    Goitom, Berhe; Hammond, James; Kendall, Michael; Nowacky, Andy; Keir, Derek; Oppenheimer, Clive; Ogubazghi, Ghebrebrhan; Ayele, Atalay; Ibrahim, Said; Jacques, Eric

    2014-05-01

    Nabro volcano, located in south-east Eritrea, East Africa, lies at the eastern margin of the Afar Rift and the Danakil Depression. Its tectonic behaviour is controlled by the divergence of the Arabian, Nubian and Somali plates. Nabro volcano was thought to be seismically quiet until it erupted in June 2011 with limited warning. The volcano erupted on June 12, 2011 around 20:32 UTC, following a series of earthquakes on that day that reached a maximum magnitude of 5.8. It is the first recorded eruption of Nabro volcano and only the second in Eritrea, following the Dubbi eruption in 1861. A lava flow emerged from the caldera and travelled about 20 km from the vent and buried settlements in the area. At the time of this eruption there was no seismic network in Eritrea, and hence the volcano was not monitored. In this study we use ten Ethiopian, one Yemeni and one Djibouti stations to investigate the seismicity of the area before, during and after the eruption. Four Eritrean seismic stations deployed in June 2011, four days after the eruption, are also included in the dataset. Travel time picks supplied by colleagues from Djibouti were also incorporated into the dataset. Our analysis covers roughly three months before and after the eruption and shows that Nabro was seismically quiet before the eruption (nine events), with the exception of one major earthquake (4.8 magnitude) that occurred on March 31, 2011. In contrast, the region shows continued seismic activity after the eruption (92 events). During the eruption seismicity levels are high (123 events), with two days particularly active, June 12 and June 17 with 85 and 28 discrete events, respectively. Maximum magnitudes of 5.8 and 5.9 were recorded on these two days. The two days of increased seismicity are consistent with satellite observations of the eruption which show two distinct phases of the eruption. The period between these two phases was dominated by volcanic tremor. The tremor signal lasted for almost one

  13. Eruption dynamics and explosive-effusive transitions during the 1400 cal BP eruption of Opala volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Andrews, Benjamin J.; Dufek, Josef; Ponomareva, Vera

    2018-05-01

    Deposits and pumice from the 1400 cal BP eruption of Opala volcano record activity that occurred at the explosive-effusive transition, resulting in intermittent, or stop-start, behavior, where explosive activity resumed following a pause. The eruption deposited distinctive, biotite-bearing rhyolite tephra across much of Kamchatka, and its stratigraphy consists of a lithic-rich pumice fall, overlain by pumice falls and pyroclastic density deposits, with the proportion of the latter increasing with height. This sequence repeats such that the middle of the total deposit is marked by a lithic-rich fall with abundant obsidian clasts. Notably, the eruptive pumice are poorly vesiculated, with vesicle textures that record fragmentation of a partially collapsed magmatic foam. The eruption vent, Baranii Amphitheater is filled with obsidian lavas of the same composition as the rhyolite tephra. Based upon the stratigraphic and compositional relations, we divide the eruption into four phases. Phase I initiated with eruption of a lithic-rich pumice fall, followed by eruption of Plinian falls and pyroclastic density currents. During Phase II, the eruption paused for at least 5-6 h; in this time, microlites nucleated and began to grow in the magma. Phase III essentially repeated the Phase I sequence. Obsidian lavas were emplaced during Phase IV. The pumice textures suggest that the magma ascended very near the threshold decompression rate for the transition between explosive (fast) and effusive (slow) behavior. The pause during Phase II likely occurred as decompression slowed enough for the magma to develop sufficient permeability for gas to escape resulting in collapse of the magmatic foam, stopping the eruption and temporarily sealing the conduit. After about 5-6 h, eruption resumed with, once again, magma decompressing very near the explosive-effusive transition. Phase III ended when the decompression rate slowed and lava dome emplacement began. Distributions of pumice and

  14. Episode 49 of the Pu'u 'Ō'ō-Kūpaianaha eruption of Kilauea volcano-breakdown of a steady-state eruptive era

    USGS Publications Warehouse

    Mangan, M.T.; Heliker, C.C.; Mattox, T.N.; Kauahikaua, J.P.; Helz, R.T.

    1995-01-01

    The Pu'u 'O'o-Kupaianaha eruption (1983-present) is the longest lived rift eruption of either Kilauea or neighboring Mauna Loa in recorded history. The initial fissure opening in January 1983 was followed by three years of episodic fire fountaining at the Pu'u 'O'o vent on Kilauea's east rift zone ∼19km from the summit (episodes 4–47). These spectacular events gave way in July 1986 to five and a half years of near-continuous, low-level effusion from the Kupaianaha vent, ∼ 3km to the cast (episode 48). A 49th episode began in November 1991 with the opening of a new fissure between Pu'u 'O'o and Kupaianaha. This three week long outburst heralded an era of more erratic eruptive behavior characterized by the shut down of Kupaianaha in February 1992 and subsequent intermittent eruption from vents on the west flank of Pu'u 'O'o (episodes 50 and 51). The events occurring over this period are due to progressive shrinkage of the rift-zone reservoir beneath the eruption site, and had limited impact on eruption temperatures and lava composition.

  15. 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.

  16. Hydrogen sulphide eruptions in the Atlantic Ocean off southern Africa: implications of a new view based on SeaWiFS satellite imagery

    NASA Astrophysics Data System (ADS)

    Weeks, Scarla J.; Currie, Bronwen; Bakun, Andrew; Peard, Kathleen R.

    2004-02-01

    Conventional wisdom has held that eruptions of toxic hydrogen sulphide that occur from time to time in the ocean off southwestern Africa were rather isolated near-coastal features, limited both in extent and in ecosystem-scale consequences. Now, however, it has become possible to identify sulphide outbreaks by satellite remote sensing. This new capability appears to lead to a complete revision of the conventional view, with some eruption episodes being observed to affect areas of ocean surface exceeding 20,000 km 2. The occurrences are also seen to be more frequent and longer lasting than previously supposed. Example sequences of Sea-viewing Wide Field of View (SeaWiFS) images are presented to indicate general classes of eruption types that are observed and to support discussion of potential eruption mechanisms. Certain methodological problems in interpreting effects on local productivity are outlined. Spatial configurations of eruptions indicate that simple upward advection in the upwelling process may not be a sufficient explanation for the range of eruption characteristics experienced. Eruptions seem often to be coincident with one of two contrasting types of atmospheric weather situation: either (1) increased intensity of wind driven coastal upwelling, or (2) indications of passage of a low pressure weather cell (e.g. interruption of coastal upwelling, sudden warming of the sea surface, rainfall in the hinterland). Such a pattern may imply that related lowering of hydrostatic pressure at depth may tend to trigger incipient eruptions. It also suggests an episodic mechanism driven by the buoyancy introduced by the effervescence of gases trapped by hydrostatic pressure within the sea-floor sediments. Connotations of these phenomena to the local ecology and to that of the entire Benguela Current regional ecosystem would appear to be major. Their relevance to the valuable but extremely variable fishery resource populations of the region, which have undergone drastic

  17. Remote sensing and petrological observations on the 2012-2013 fissure eruption at Tolbachik volcano, Kamchatka: Implications for reconstruction of the eruption chronology

    NASA Astrophysics Data System (ADS)

    Melnikov, Dmitry; Volynets, Anna O.

    2015-12-01

    We present a reconstruction of the chronological sequence of events that took place during the first days of the 2012-2013 Tolbachik fissure eruption using petrological data and remote sensing methods. We were forced to use this approach because bad weather conditions did not allow direct observations during the first two days of the eruption. We interpreted infrared images from the scanning radiometer VIIRS Suomi NPP and correlated the output with the results of the geochemical study, including comparison of the ash, deposited at the period from 27 to 29 November, with the samples of lava and bombs erupted from the Menyailov and Naboko vents. We argue that the compositional change observed in the eruption products (the decrease of SiO2 concentration and K2O/MgO ratio, increase of MgO concentration and Mg#) started approximately 24 h after the eruption began. At this time the center of activity moved to the southern part of the fissure, where the Naboko group of vents was formed; therefore, this timeframe also characterizes the timing of the Naboko vent opening. The Naboko group of vents remained active until the end of eruption in September 2013.

  18. Worldwide environmental impacts from the eruption of Thera

    NASA Astrophysics Data System (ADS)

    Lamoreaux, P. E.

    1995-10-01

    The eruptions of Thera (Santorini) between 1628 and 1450 BC constituted a natural catastrophe unparalleled in all of history. The last major eruption in 1450 BC destroyed the entire Minoan Fleet at Crete at a time when the Minoans dominated the Mediterranean world. In addition, there had to be massive loss of life from ejecta gases, volcanic ash, bombs, and flows. The collapse of a majestic mountain into a caldera 15 km in diameter caused a giant ocean wave, a tsunami, that at its source was estimated in excess of 46 m high. The tsunami destroyed ships as far away as Crete (105 km) and killed thousands of people along the shorelines in the eastern Mediterranean area. At distant points in Asia Minor and Africa, there was darkness from ash fallout, lightning, and destructive earthquakes. Earthquake waves emanating from the epicenter near the ancient volcano were felt as far away as the Norwegian countries. These disturbances caused great physical damage in the eastern Mediterranean and along the rift valley system from Turkey to the south into central Africa. They caused major damage and fires in north Africa from Sinai to Alexandria, Egypt. Volcanic ash spread upward as a pillar of fire and clouds into the atmosphere and blocked out the sun for many days. The ash reached the stratosphere and moved around the world where the associated gases and fine particulate matter impacted the atmosphere, soils, and waters. Ground-hugging, billowing gases moved along the water surface and destroyed all life downwind, probably killing those who attempted to flee from Thera. The deadly gases probably reached the shores of north Africa. Climatic changes were the aftermath of the eruption and the atmospheric plume was to eventually affect the bristlecone pine of California; the bog oaks of Ireland, England, and Germany, and the grain crops of China. Historical eruptions at Krakatau, Tambora, Vesuvius, and, more currently, eruptions at Nevado del Ruiz, Pinatubo, and Mount Saint

  19. The character of long-term eruptions: Inferences from episodes 50-53 of the Pu'u 'Ō'ō-Kūpaianaha eruption of Kīlauea volcano

    USGS Publications Warehouse

    Heliker, C.C.; Mangan, M.T.; Mattox, T.N.; Kauahikaua, J.P.; Helz, R.T.

    1998-01-01

    The Pu'u 'Ō'ō-Kūpaianaha eruption on the east rift zone of Kīlauea began in January 1983. The first 9 years of the eruption were divided between the Pu'u 'Ō'ō (1983–1986) and Kūpaianaha (1986–1992) vents, each characterized by regular, predictable patterns of activity that endured for years. In 1990 a series of pauses in the activity disturbed the equilibrium of the eruption, and in 1991, the output from Kūpaianaha steadily declined and a short-lived fissure eruption broke out between Kūpaianaha and Pu'u 'Ō'ō. In February 1992 the Kūpaianaha vent died, and, 10 days later, eruptive episode 50 began as a fissure opened on the uprift flank of the Pu'u 'Ō'ō cone. For the next year, the eruption was marked by instability as more vents opened on the flank of the cone and the activity was repeatedly interrupted by brief pauses in magma supply to the vents. Episodes 50–53 constructed a lava shield 60 m high and 1.3 km in diameter against the steep slope of the Pu'u 'Ō'ō cone. By 1993 the shield was pockmarked by collapse pits as vents and lava tubes downcut as much as 29 m through the thick deposit of scoria and spatter that veneered the cone. As the vents progressively lowered, the level of the Pu'u 'Ō'ō pond also dropped, demonstrating the hydraulic connection between the two. The downcutting helped to undermine the prominent Pu'u 'Ō'ō cone, which has diminished in size both by collapse, as a large pit crater formed over the conduit, and by burial of its flanks. Intervals of eruptive instability, such as that of 1991–1993, accelerate lateral expansion of the subaerial flow field both by producing widely spaced vents and by promoting surface flow activity as lava tubes collapse and become blocked during pauses.

  20. Chronology and volcanology of the 1949 multi-vent rift-zone eruption on La Palma (Canary Islands)

    NASA Astrophysics Data System (ADS)

    Klügel, A.; Schmincke, H.-U.; White, J. D. L.; Hoernle, K. A.

    1999-12-01

    The compositionally zoned San Juan eruption on La Palma emanated from three eruptive centers located along a north-south-trending rift zone in the south of the island. Seismic precursors began weakly in 1936 and became strong in March 1949, with their foci progressing from the north of the rift zone towards its south. This suggests that magma ascended beneath the old Taburiente shield volcano and moved southward along the rift. The eruption began on June 24, 1949, with phreatomagmatic activity at Duraznero crater on the ridgetop (ca. 1880 m above sea level), where five vents erupted tephritic lava along a 400-m-long fissure. On June 8, the Duraznero vents shut down abruptly, and the activity shifted to an off-rift fissure at Llano del Banco, located at ca. 550 m lower elevation and 3 km to the northwest. This eruptive center issued initially tephritic aa and later basanitic pahoehoe lava at high rates, producing a lava flow that entered the sea. Two days after basanite began to erupt at Llano del Banco, Hoyo Negro crater (ca. 1880 m asl), located 700 m north of Duraznero along the rift, opened on July 12 and produced ash and bombs of basanitic to phonotephritic composition in violent phreatomagmatic explosions ( White and Schmincke, 1999). Llano del Banco and Hoyo Negro were simultaneously active for 11 days and showed a co-variance of their eruption rates indicating a shallow hydraulic connection. On July 30, after 3 days of quiescence at all vents, Duraznero and Hoyo Negro became active again during a final eruptive phase. Duraznero issued basanitic lava at high rates for 12 h and produced a lava flow that descended towards the east coast. The lava contains ca. 1 vol.% crustal and mantle xenoliths consisting of 40% tholeiitic gabbros from the oceanic crust, 35% alkaline gabbros, and 20% ultramafic cumulates. The occurrence of xenoliths almost exclusively in the final lava is consistent with their origin by wall-rock collapse at depth near the end of the eruption

  1. Is Kīlauea's East Rift Zone eruption running out of gas?

    NASA Astrophysics Data System (ADS)

    Sutton, A. J.; Elias, T.; Orr, T. R.; Patrick, M. R.; Poland, M. P.; Thornber, C. R.

    2015-12-01

    Gases exsolving from magma are a key force that drives eruptive activity, and emissions from Kīlauea's East Rift Zone (ERZ) dominated the volcano's gas release from the beginning of the long-running and voluminous Pu'u 'Ō'ō eruption in 1983, through February 2008. In the months prior to the March 2008 onset of eruptive activity within Halema'uma'u Crater, however, SO2 degassing at the summit climbed substantially, and summit gas release has remained elevated since. These unprecedented emissions associated with the new summit eruption effectively began robbing gas from magma destined for Kīlauea's ERZ. As a result, ERZ SO2discharge, which had averaged 1,700 +-380 t/d for the previous 15 years, declined sharply and steadily beginning in September, 2008, and reached a new steady low of 380 +- 100 t/d by early 2011. This level persisted through mid-2015. In the years since the late 2008 downturn in ERZ SO2 emissions, there has been an overall slowdown in ERZ eruptive activity. Elevated emissions and effusive activity occurred briefly during the 2011 Kamoamoa fissure eruption and two other outbreaks at Pu'u 'Ō'ō , but otherwise ERZ eruptive activity had waned by 2010, when effusion rates were measured at about half of the long-term rate. Also, the sulfur preserved in ERZ olivine melt-inclusions, which provides a record of pre-eruptive SO2degassing, has steadily declined along with equilibration temperatures of host olivine phenocrysts, since 2008. We suggest that the drop in gas content of magma reaching the ERZ, owing to summit pre-eruptive degassing, has contributed significantly to the downturn in ERZ activity. While SO2 emissions from the ERZ have dropped to sustained levels lower than anything seen in the past 20 years, summit emissions have remained some of the highest recorded since regular measurements began at Kīlauea in 1979. Overall, average total SO2 discharge from Kīlauea in 2014, summit and ERZ, is still about 50% higher than for the 15 years prior

  2. The 2013 eruption of Pavlof Volcano, Alaska: a spatter eruption at an ice- and snow-clad volcano

    USGS Publications Warehouse

    Waythomas, Christopher F.; Haney, Matthew M.; Fee, David; Schneider, David J.; Wech, Aaron G.

    2014-01-01

    The 2013 eruption of Pavlof Volcano, Alaska began on 13 May and ended 49 days later on 1 July. The eruption was characterized by persistent lava fountaining from a vent just north of the summit, intermittent strombolian explosions, and ash, gas, and aerosol plumes that reached as high as 8 km above sea level and on several occasions extended as much as 500 km downwind of the volcano. During the first several days of the eruption, accumulations of spatter near the vent periodically collapsed to form small pyroclastic avalanches that eroded and melted snow and ice to form lahars on the lower north flank of the volcano. Continued lava fountaining led to the production of agglutinate lava flows that extended to the base of the volcano, about 3–4 km beyond the vent. The generation of fountain-fed lava flows was a dominant process during the 2013 eruption; however, episodic collapse of spatter accumulations and formation of hot spatter-rich granular avalanches was a more efficient process for melting snow and ice and initiating lahars. The lahars and ash plumes generated during the eruption did not pose any serious hazards for the area. However, numerous local airline flights were cancelled or rerouted, and trace amounts of ash fall occurred at all of the local communities surrounding the volcano, including Cold Bay, Nelson Lagoon, Sand Point, and King Cove.

  3. 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.

  4. Nyiragongo Volcano Erupts in the Congo

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Mount Nyiragongo, located in the Democratic Republic of the Congo, erupted today (January 17, 2002), ejecting a large cloud of smoke and ash high into the sky and spewing lava down three sides of the volcano. Mount Nyiragongo is located roughly 10 km (6 miles) north of the town of Goma, near the Congo's border with Rwanda. According to news reports, one river of lava is headed straight toward Goma, where international aid teams are evacuating residents. Already, the lava flows have burned through large swaths of the surrounding jungle and have destroyed dozens of homes. This false-color image was acquired today (January 17) by the Moderate-resolution Imaging Spectroradiometer (MODIS) roughly 5 hours after the eruption began. Notice Mount Nyiragongo's large plume (bright white) can be seen streaming westward in this scene. The plume appears to be higher than the immediately adjacent clouds and so it is colder in temperature, making it easy for MODIS to distinguish the volcanic plume from the clouds by using image bands sensitive to thermal radiation. Images of the eruption using other band combinations are located on the MODIS Rapid Response System. Nyiragongo eruptions are extremely hazardous because the lava tends to be very fluid and travels down the slopes of the volcano quickly. Eruptions can be large and spectacular, and flows can reach up to 10s of kilometers from the volcano very quickly. Also, biomass burned from Nyriagongo, and nearby Mount Nyamuragira, eruptions tends to create clouds of smoke that adversely affect the Mountain Gorillas living in the adjacent mountain chain. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  5. The 2009 eruption of Redoubt Volcano, Alaska

    USGS Publications Warehouse

    Bull, Katharine F.; Cameron, Cheryl; Coombs, Michelle L.; Diefenbach, Angie; Lopez, Taryn; McNutt, Steve; Neal, Christina; Payne, Allison; Power, John A.; Schneider, David J.; Scott, William E.; Snedigar, Seth; Thompson, Glenn; Wallace, Kristi; Waythomas, Christopher F.; Webley, Peter; Werner, Cynthia A.; Schaefer, Janet R.

    2012-01-01

    Redoubt Volcano, an ice-covered stratovolcano on the west side of Cook Inlet, erupted in March 2009 after several months of escalating unrest. The 2009 eruption of Redoubt Volcano shares many similarities with eruptions documented most recently at Redoubt in 1966–68 and 1989–90. In each case, the eruptive phase lasted several months, consisted of multiple ashproducing explosions, produced andesitic lava and tephra, removed significant amounts of ice from the summit crater and Drift glacier, generated lahars that inundated the Drift River valley, and culminated with the extrusion of a lava dome in the summit crater. Prior to the 2009 explosive phase of the eruption, precursory seismicity lasted approximately six months with the fi rst weak tremor recorded on September 23, 2008. The first phreatic explosion was recorded on March 15, and the first magmatic explosion occurred seven days later, at 22:34 on March 22. The onset of magmatic explosions was preceded by a strong, shallow swarm of repetitive earthquakes that began about 04:00 on March 20, 2009, less than three days before an explosion. Nineteen major ash-producing explosions generated ash clouds that reached heights between 17,000 ft and 62,000 ft (5.2 and 18.9 km) ASL. During ash fall in Anchorage, the Ted Stevens International Airport was shut down for 20 hours, from ~17:00 on March 28 until 13:00 on March 29. On March 23 and April 4, lahars with fl ow depths to 10 m in the upper Drift River valley inundated parts of the Drift River Terminal (DRT). The explosive phase ended on April 4 with a dome collapse at 05:58. The April 4 ash cloud reached 50,000 ft (15.2 km) and moved swiftly to the southeast, depositing up to 2 mm of ash fall in Homer, Anchor Point, and Seldovia. At least two and possibly three lava domes grew and were destroyed by explosions prior to the final lava dome extrusion that began after the April 4 event. The fi nal lava dome ceased growth by July 1, 2009, with an estimated volume of 72

  6. The transition from explosive to effusive eruptive regime: The example of the 1912 Novarupta eruption, Alaska

    USGS Publications Warehouse

    Adams, N.K.; Houghton, Bruce F.; Fagents, S.A.; Hildreth, W.

    2006-01-01

    The shift from explosive to effusive silicic volcanism seen in many historical eruptions reflects a change in the style of degassing of erupted magma. This paper focuses on such a transition during the largest eruption of the twentieth century, the 1912 eruption of Novarupta. The transition is recorded in a dacite block bed, which covers an elliptical area of 4 km2 around the vent. Approximately 700 studied blocks fall into four main lithologic categories: (1) pumiceous, (2) dense, (3) flow-banded dacites, and (4) welded breccias. Textural analyses of the blocks indicate portions of the melt underwent highly variable degrees of outgassing. Vesicle populations show features characteristic of bubble coalescence and collapse. A decrease in measured vesicularity and increased evidence for bubble collapse compared with pumice from earlier Plinian episodes mark the transition from closed- to open-system degassing. Block morphology and textures strongly suggest the magma was first erupted as a relatively gas-rich lava dome/plug, but incomplete out-gassing led to explosive disruption. Heterogeneous degassing of ascending magma began in Plinian Episode III and resulted in instability during Episode IV dome growth and a (series of) Vulcanian explosion(s). Modeling of the dynamics of explosion initiation and ejecta dispersal indicates that a significant concentration in gas is required to produce the explosions responsible for the observed block field dispersal. The amount of gas available in the hot pumiceous dome material appears to have been inadequate to drive the explosion(s); therefore, external water most likely contributed to the destruction. ?? 2006 Geological Society of America.

  7. The 2011 submarine volcanic eruption of El Hierro Island (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    López, C.; Blanco, M. J.

    2012-04-01

    On 10 October 2011 a submarine volcanic eruption began 2 km SW of La Restinga village in the South coast of El Hierro Island (Spain). It became the first submarine eruption reported in 500 years of historical record in the Canary Islands. The eruption took place after three months of intensive seismic activity and ground deformation. The first signal evidencing the eruption was a harmonic tremor signal, located somewhere in the South sector of El Hierro Island and registered in every seismic station on the island. On the following day, the tremoŕs amplitude increased up enough to be felt by the residents of La Restinga. The first visual evidence of the eruption was observed during the afternoon of 12 October, a large light-green coloured area on the sea surface, 2 km to the SW of La Restinga. Three days later, steaming lava fragments were observed floating on the sea, in the area where the vent was supposed to be located. These fragments had a bomb-like shape and their sizes ranged between 10 and 40 cm long. They were bicoloured, a black outer part with a basaltic composition, and a white inner part, highly vesiculated and rich in silica content (>60%). This type of fragments was only observed during the first days of the eruption. Within the next two months further emission episodes have been observed with turbulent water, foam rings and large bubbles on the sea surface. On the 27th of November new lava fragments were observed while floating and degassing on the sea surface. Most of them were "lava balloons" or hollow fragments of lavas, with sizes between 30 and 200 cm, and highly vesiculated outer crust of basaltic-basanitic and sideromelane composition. The emission of these products continues intermitently up to date (January 2012) During the eruption, the GPS monitoring network detected episodes of inflation-deflation and a maximum vertical deformation of 4 cm. The horizontal deformation, which had reached up to 5 cm before the eruption, remains stable. The

  8. First recorded eruption of Nabro volcano, Eritrea, 2011.

    PubMed

    Goitom, Berhe; Oppenheimer, Clive; Hammond, James O S; Grandin, Raphaël; Barnie, Talfan; Donovan, Amy; Ogubazghi, Ghebrebrhan; Yohannes, Ermias; Kibrom, Goitom; Kendall, J-Michael; Carn, Simon A; Fee, David; Sealing, Christine; Keir, Derek; Ayele, Atalay; Blundy, Jon; Hamlyn, Joanna; Wright, Tim; Berhe, Seife

    We present a synthesis of diverse observations of the first recorded eruption of Nabro volcano, Eritrea, which began on 12 June 2011. While no monitoring of the volcano was in effect at the time, it has been possible to reconstruct the nature and evolution of the eruption through analysis of regional seismological and infrasound data and satellite remote sensing data, supplemented by petrological analysis of erupted products and brief field surveys. The event is notable for the comparative rarity of recorded historical eruptions in the region and of caldera systems in general, for the prodigious quantity of SO 2 emitted into the atmosphere and the significant human impacts that ensued notwithstanding the low population density of the Afar region. It is also relevant in understanding the broader magmatic and tectonic significance of the volcanic massif of which Nabro forms a part and which strikes obliquely to the principal rifting directions in the Red Sea and northern Afar. The whole-rock compositions of the erupted lavas and tephra range from trachybasaltic to trachybasaltic andesite, and crystal-hosted melt inclusions contain up to 3,000 ppm of sulphur by weight. The eruption was preceded by significant seismicity, detected by regional networks of sensors and accompanied by sustained tremor. Substantial infrasound was recorded at distances of hundreds to thousands of kilometres from the vent, beginning at the onset of the eruption and continuing for weeks. Analysis of ground deformation suggests the eruption was fed by a shallow, NW-SE-trending dike, which is consistent with field and satellite observations of vent distributions. Despite lack of prior planning and preparedness for volcanic events in the country, rapid coordination of the emergency response mitigated the human costs of the eruption.

  9. Characterizing the first historic eruption of Nabro, Eritrea: Insights from thermal and UV remote sensing

    NASA Astrophysics Data System (ADS)

    Sealing, Christine R.

    June 2011 saw the first historic eruption of Nabro volcano, one of 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. Due to its remote location, little was known about this event in terms of the quantity of erupted products and the timing and mechanisms of their emplacement. 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 are limited. Using free, publicly available satellite data, I examined rates of lava effusion and SO2 emission in order to quantify the amount of erupted products and understand the temporal evolution of the eruption, as well as explore what information can be gleaned about eruption mechanisms using remote sensing data. These data revealed 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 gave way to 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. The 2011 eruption of Nabro lasted nearly 6 weeks, and may be considered the second largest historic eruption in Africa. Work such as this highlights the importance of satellite remote sensing for studying and monitoring volcanoes, particularly those in remote regions that may be otherwise inaccessible.

  10. Phreatomagmatic eruptive and depositional processes during the 1949 eruption on La Palma (Canary Islands)

    NASA Astrophysics Data System (ADS)

    White, James D. L.; Schmincke, Hans-Ulrich

    1999-12-01

    In 1949, a 5-week-long magmatic and phreatomagmatic eruption took place along the active volcanic ridge of La Palma (Canary Islands). Two vents, Duraznero and Hoyo Negro, produced significant pyroclastic deposits. The eruption began from Duraznero vent, which produced a series of deposits with an upward decrease in accidental fragments and increase in fluidal ash and spatter, together inferred to indicate decreasing phreatomagmatic interaction. Hoyo Negro erupted over a 2-week period, producing a variety of pyroclastic density currents and ballistic blocks and bombs. Hoyo Negro erupted within and modified an older crater having high walls on the northern to southeastern edges. Southwestern to western margins of the crater lay 50 to 100 m lower. Strongly contrasting deposits in the different sectors (N-SE vs. SW-W) were formed as a result of interaction between topography, weak eruptive columns and stratified pyroclastic density currents. Tephra ring deposits are thicker and coarser-grained than upper rim deposits formed along the higher edges of the crater, and beyond the crater margin, valley-confined deposits are thicker than more thinly bedded mantling deposits on higher topography. These differences indicate that the impact zone for the bulk of the collapsing, tephra-laden column lay within the crater and that the high crater walls inhibited escape of pyroclastic density currents to the north and east. The impact zone lay outside the low SW-W rims, however, thus allowing stratified pyroclastic density currents to move freely away from the crater in those directions, depositing thin sections (<30 cm) of well-bedded ash (mantling deposits) on ridges and thicker sections (1-3 m) of structureless ash beds in valleys and small basins. Such segregation of dense pyroclastic currents from more dilute ones at the crater wall is likely to be common for small eruptions from pre-existing craters and is an important factor to be taken into account in volcanic hazards

  11. Storage, migration, and eruption of magma at Kilauea volcano, Hawaii, 1971-1972

    USGS Publications Warehouse

    Duffield, W.A.; Christiansen, R.L.; Koyanagi, R.Y.; Peterson, D.W.

    1982-01-01

    The magmatic plumbing system of Kilauea Volcano consists of a broad region of magma generation in the upper mantle, a steeply inclined zone through which magma rises to an intravolcano reservoir located about 2 to 6 km beneath the summit of the volcano, and a network of conduits that carry magma from this reservoir to sites of eruption within the caldera and along east and southwest rift zones. The functioning of most parts of this system was illustrated by activity during 1971 and 1972. When a 29-month-long eruption at Mauna Ulu on the east rift zone began to wane in 1971, the summit region of the volcano began to inflate rapidly; apparently, blockage of the feeder conduit to Mauna Ulu diverted a continuing supply of mantle-derived magma to prolonged storage in the summit reservoir. Rapid inflation of the summit area persisted at a nearly constant rate from June 1971 to February 1972, when a conduit to Mauna Ulu was reopened. The cadence of inflation was twice interrupted briefly, first by a 10-hour eruption in Kilauea Caldera on 14 August, and later by an eruption that began in the caldera and migrated 12 km down the southwest rift zone between 24 and 29 September. The 14 August and 24-29 September eruptions added about 107 m3 and 8 ?? 106 m3, respectively, of new lava to the surface of Kilauea. These volumes, combined with the volume increase represented by inflation of the volcanic edifice itself, account for an approximately 6 ?? 106 m3/month rate of growth between June 1971 and January 1972, essentially the same rate at which mantle-derived magma was supplied to Kilauea between 1952 and the end of the Mauna Ulu eruption in 1971. The August and September 1971 lavas are tholeiitic basalts of similar major-element chemical composition. The compositions can be reproduced by mixing various proportions of chemically distinct variants of lava that erupted during the preceding activity at Mauna Ulu. Thus, part of the magma rising from the mantle to feed the Mauna Ulu

  12. Seismo-acoustic evidence for an avalanche driven phreatic eruption through a beheaded hydrothermal system: An example from the 2012 Tongariro eruption

    USGS Publications Warehouse

    Jolly, A.D.; Jousset, P.; Lyons, J.J.; Carniel, R.; Fournier, R.; Fry, B.; Miller, C.

    2016-01-01

    The 6 August 2012 Te Maari eruption comprises a complex eruption sequence including multiple eruption pulses, a debris avalanche that propagated ~ 2 km from the vent, and the formation of a 500 m long, arcuate chasm, located ~ 300 m from the main eruption vent. The eruption included 6 distinct impulses that were coherent across a local infrasound network marking the eruption onset at 11:52:18 (all times UTC). An eruption energy release of ~ 3 × 1012 J was calculated using a body wave equation for radiated seismic energy. A similar calculation based on the infrasound record, shows that ~ 90% of the acoustic energy was released from three impulses at onset times 11:52:20 (~ 20% of total eruption energy), 11:52:27 (~ 50%), and 11:52:31 (~ 20%). These energy impulses may coincide with eyewitness accounts describing an initial eastward directed blast, followed by a westward directed blast, and a final vertical blast. Pre-eruption seismic activity includes numerous small unlocatable micro-earthquakes that began at 11:46:50. Two larger high frequency earthquakes were recorded at 11:49:06 and 11:49:21 followed directly by a third earthquake at 11:50:17. The first event was located within the scarp based on an arrival time location from good first P arrival times and probably represents the onset of the debris avalanche. The third event was a tornillo, characterised by a 0.8 Hz single frequency resonance, and has a resonator attenuation factor of Q ~ 40, consistent with a bubbly fluid filled resonator. This contrasts with a similar tornillo event occurring 2.5 weeks earlier having Q ~ 250–1000, consistent with a dusty gas charged resonator. We surmise from pre-eruption seismicity, and the observed attenuation change, that the debris avalanche resulted from the influx of fluids into the hydrothermal system, causing destabilisation and failure. The beheaded hydrothermal system may have then caused depressurisation frothing of the remaining gas charged system leading to the

  13. FOGO-2014: Monitoring the Fogo 2014 Eruption, Cape Verde

    NASA Astrophysics Data System (ADS)

    Fernandes, Rui; Faria, Bruno

    2015-04-01

    Fogo volcano, located in the Cape Verde Archipelago offshore Western Africa, is a complete stratovolcano system that was created by the Cape Verde hotspot, forming the island of Fogo. The top (Pico do Fogo) reaches ~2830m above sea level, and raises ~1100m above Chã das Caldeiras, an almost flat circular area with approximately 10 kilometres in the north-south direction and 7 kilometres in the east-west direction. Chã das Caldeiras, surrounded towards the West by the ~1000m high Bordeira rampart, has been inhabited since the early 20th Century, because it is one of the most productive agricultural areas in this semi-arid country. Fogo volcano erupted on November 23, 2014 (~10:00UTC) on a subsidiary vent of the main cone, after 19 years of inactivity. C4G (Collaboratory for Geosciences), a distributed research infrastructure created in 2014 in the framework of the Portuguese Roadmap for Strategic Research Infrastructures, immediately offered support to the Cape Verdean authorities, with the goal of complementing the permanent geophysical monitoring network operated in Fogo island by INMG, the Cape Verdean Meteorological and Geophysical Institute. This permanent network is composed of seven seismographic stations and three tiltmeter stations, and the data is transmitted in real time to the INMG geophysical laboratory in São Vicente Island, where it is analysed on a routine basis. Pre-eruptive activity started to be detected by the permanent monitoring network on October 2014, with earthquakes occurring at depths larger than 15 km. These events led to a first volcanic warning to the Cape Verdean Civil Protection Agency. On November 22 several volcano-tectonic earthquakes were recorded at shallow depths, indicating shallow fracturing. On the basis of this activity, INMG issued a formal alert of an impending eruption to the Civil Protection Agency, ~24 hours before the onset of the eruption. Volcanic tremor and clear tiltmeter signals were recorded about one hour

  14. Ground deformation associated with the precursory unrest and early phases of the January 2006 eruption of Augustine volcano, Alaska

    USGS Publications Warehouse

    Cervelli, P.F.; Fournier, T.; Freymueller, Jeffrey T.; Power, J.A.

    2006-01-01

    On January 11, 2006 Augustine Volcano erupted after nearly 20 years of quiescence. Global Positioning System (GPS) instrumentation at Augustine, consisting of six continuously recording, telemetered receivers, measured clear precursory deformation consistent with a source of inflation or pressurization beneath the volcano's summit at a depth of around sea level. Deformation began in early summer 2005, and was preceded by a subtle, but distinct, increase in seismicity, which began in May 2005. After remaining more or less constant, deformation rates accelerated on at least three stations beginning in late November 2005. After this date, GPS data suggest the upward propagation of a small dike into the edifice, which, based on the style of deformation and high levels of gas emission, appears to have ascended to shallow levels by mid-December 2005, about four weeks before the eruption began.

  15. Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming

    USGS Publications Warehouse

    Till, Christy B.; Vazquez, Jorge A.; Boyce, Jeremy W

    2015-01-01

    Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at calderas with protracted histories of eruption and unrest such as Yellowstone, Long Valley, and Valles, USA. Although orders of magnitude smaller in volume than rare caldera-forming super-eruptions, these relatively frequent effusions of rhyolite are comparable to the largest eruptions of the 20th century and pose a considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption of silicic magma is unclear particularly because the time between reheating of a subvolcanic intrusion and eruption is poorly quantified. This study uses geospeedometry of trace element profiles with nanometer resolution in sanidine crystals to reveal that Yellowstone’s most recent volcanic cycle began when remobilization of a near- or sub-solidus silicic magma occurred less than 10 months prior to eruption, following a 220,000 year period of volcanic repose. Our results reveal a geologically rapid timescale for rejuvenation and effusion of ~3 km3 of high-silica rhyolite lava even after protracted cooling of the subvolcanic system, which is consistent with recent physical modeling that predict a timescale of several years or less. Future renewal of rhyolitic volcanism at Yellowstone is likely to require an energetic intrusion of mafic or silicic magma into the shallow subvolcanic reservoir and could rapidly generate an eruptible rhyolite on timescales similar to those documented here.

  16. Thermal precursors in satellite images of the 1999 eruption of Shishaldin Volcano

    NASA Astrophysics Data System (ADS)

    Dehn, Jonathan; Dean, Kenneson; Engle, Kevin; Izbekov, Pavel

    2002-07-01

    Shishaldin Volcano, Unimak Island Alaska, began showing signs of thermal unrest in satellite images on 9 February 1999. A thermal anomaly and small steam plume were detected at the summit of the volcano in short-wave thermal infrared AVHRR (advanced very high resolution radiometer) satellite data. This was followed by over 2 months of changes in the observed thermal character of the volcano. Initially, the thermal anomaly was only visible when the satellite passed nearly directly over the volcano, suggesting a hot source deep in the central crater obscured from more oblique satellite passes. The "zenith angle" needed to see the anomaly increased with time, presumably as the thermal source rose within the conduit. Based on this change, an ascent rate of ca. 14 m per day for the thermal source was estimated, until it reached the summit on around 21 March. It is thought that Strombolian activity began around this time. The precursory activity culminated in a sub-Plinian eruption on 19 April, ejecting ash to over 45,000 ft. (13,700 m). The thermal energy output through the precursory period was calculated based on geometric constraints unique to Shishaldin. These calculations show fluctuations that can be tied to changes in the eruptive character inferred from seismic records and later geologic studies. The remote location of this volcano made satellite images a necessary observation tool for this eruption. To date, this is the longest thermal precursory activity preceding a sub-Plinian eruption recorded by satellite images in the region. This type of thermal monitoring of remote volcanoes is central in the efforts of the Alaska Volcano Observatory to provide timely warnings of volcanic eruption, and mitigate their associated hazards to air-traffic and local residents.

  17. Water, CO2, Cl, and F in melt inclusions in phenocrysts from three Holocene explosive eruptions, Crater Lake, Oregon

    USGS Publications Warehouse

    Bacon, C.R.; Newman, S.; Stolper, E.

    1992-01-01

    Rare melt inclusions ~100 ??m in diameter trapped near the boundaries of corroded patchy zones in plagioclase phenocrysts from Plinian pumice of three Holocene eruptions were analyzed by IR spectroscopy for molecular H2O, OH groups, and CO2 and by electron microprobe for Cl and F. The three rhyodacitic eruptions, each of which began with a Plinian phase, occurred over ~200 yr. The Llao Rock and Cleetwood eruptions ended with degassed lava flows and the subsequent climatic eruption with voluminous ignimbrite. Location of melt inclusions near boundaries of patchy zones, which are mantled by oscillatory-zoned overgrowths, suggests that their H2O concentrations represent magmatic values significantly before eruption. -from Authors

  18. The Pu`u `O`o-Kupaianaha Eruption of Kilauea Volcano: The First 20 Years

    NASA Astrophysics Data System (ADS)

    Heliker, C.

    2002-12-01

    The Pu`u `O`o-Kupaianaha eruption on Kilauea's east rift zone, which began January 3, 1983, is the volcano's longest rift-zone eruption during at least the past 600 years. The early years of the eruption were memorable for lava fountains as high as 460 m that erupted episodically from the Pu`u `O`o vent. From June 1983 through June 1986, 44 episodes of fountaining fed channeled `a`a flows and built a cinder-and-spatter cone 255-m high. For the past 16 years, however, the activity has been dominated by nearly continuous effusion, low eruption rates, and emplacement of tube-fed pahoehoe flows. The change in eruptive style began in July 1986, when the activity shifted 3 km downrift to a new vent, Kupaianaha, where overflows from a lava pond built a broad, low shield, 1 km in diameter and 56 m high. For much of the next 5.5 years, tubes delivered lava to the ocean, 12 km away. In February 1992, the Kupaianaha vent died, and the eruption returned to Pu`u `O`o, where a series of flank vents on the southwest side of the cone has erupted nearly continuously for 11 years, again producing a shield and tube-fed pahoehoe flows to the coast. Since late 1986, lava has entered the ocean over 70 percent of the time. More than 210 hectares of new land have formed during this eruption, as lava deltas build seaward over steep, prograding submarine slopes of hyaloclastic debris and pillow lava. The estimated long-term effusion rate of this eruption, averaged over its first 19 years, is approximately 0.12 km3 per year (dense-rock equivalent). The total volume of lava produced, 2.1 km3, accounts for over half the volume erupted by Kilauea in the last 160 years. The composite flow field covers 105 km2 of the volcano's south flank and spans 14.5 km at the coastline, forming a lava plain 10-35 m thick. The Pu`u `O`o-Kupaianaha eruption also ranks as Hawaii's most destructive of the past two centuries. Lava flows repeatedly invaded communities on Kilauea's southern coast, destroying 186

  19. A tectonic earthquake sequence preceding the April-May 1999 eruption of Shishaldin Volcano, Alaska

    USGS Publications Warehouse

    Moran, S.C.; Stihler, S.D.; Power, J.A.

    2002-01-01

    On 4 March 1999, a shallow ML 5.2 earthquake occurred beneath Unimak Island in the Aleutian Arc. This earthquake was located 10-15 km west of Shishaldin Volcano, a large, frequently active basaltic-andesite stratovolcano. A Strombolian eruption began at Shishaldin roughly 1 month after the mainshock, culminating in a large explosive eruption on 19 April. We address the question of whether or not the eruption caused the mainshock by computing the Coulomb stress change caused by an inflating dike on fault planes oriented parallel to the mainshock focal mechanism. We found Coulomb stress increases of ???0.1 MPa in the region of the mainshock, suggesting that magma intrusion prior to the eruption could have caused the mainshock. Satellite and seismic data indicate that magma was moving upwards beneath Shishaldin well before the mainshock. indicating that, in an overall sense, the mainshock cannot be said to have caused the eruption. However, observations of changes at the volcano following the mainshock and several large aftershocks suggest that the earthquakes may, in turn, have influenced the course of the eruption.

  20. When does eruption run-up begin? Multidisciplinary insight from the 1999 eruption of Shishaldin volcano

    NASA Astrophysics Data System (ADS)

    Rasmussen, Daniel J.; Plank, Terry A.; Roman, Diana C.; Power, John A.; Bodnar, Robert J.; Hauri, Erik H.

    2018-03-01

    km, and that mixing with a shallow magma or olivine cumulates occurred in or just below the edifice (<3 km depth). Deformation was likely outside the spatial and temporal resolution of the satellite measurements. Prior to eruption magma was stored over a large range of depths (∼0-2.5 km below the summit), suggesting a shallow, vertical reservoir that could provide another explanation for the lack of detectable deformation. The earliest sign of unrest (deep long-period seismicity) coincides temporally with magmatic activity (magma mixing and a change in the local stress state), possibly indicating the beginning of eruption run-up. The more immediate run-up began with the major recharge event ∼50 days prior to eruption, after which the signs of unrest became continuous. This timescale is long compared to the seismic run-up to other basaltic eruptions (typically hours to days). Other volcanoes classified as open-system, based on their lack of precursory deformation, also tend to have relatively long run-up durations, which may be related to the time required to fill the shallow reservoir with magmas sourced from greater depth.

  1. 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

    We consider that all works, concepts on aviation safety, security codes, establishment of warning systems etc begin in 1982, when two commercial jumbo jets en route to Australia across Indonesia suffered loss of engine thrust from ingesting volcanic ash from the erupting Galunggung Volcano, Java, and descended more than 20,000 ft before the engines could be restarted (Casadevall, 1991). It is not the only incident of this kind but this Galunggung eruption had a pionner character attracting attention on aviation safety against volcanic eruptions in international community. As the needs for precautions on aviation safety against volcanic ash encounters began with Galunggung 1982 eruption and as we all concerned by the measures taken by ICAO due to Eyjafjallajökull-2010 eruption, we aimed to investigate this last huge airspace perturbing eruption and compare the volcanic ashes produced by those two eruptions. Volcanic ash characterization should be most important parameter to understand how the eruption concerned unrolled. Galunggung 1982-83 eruption was exceptionally long, lasting about nine months between 5 April 1982-8 January 1983). During this well known eruption, the composition of the erupted magma evolved from andesite (58% SiO2) to Mg-rich basalt (47% SiO2), while the style of the eruption changed drastically through time (Katili and Sudrdajat, 1984; Sudrajat and Tilling, 1984; Gourgaud et al., 1989 gourgaud etal 2000). Paralel to chemical changes and water consumption, eruption dynamic was also changed and occured in three eruption phases with different eruptive styles as an initial Vulcanian phase (5 April-13 May), a phreatomagmatic phase (17 May-28 October) and a Strombolian phase (3 November-8 January), have been recognized (Katili and Sudradjat,1984). We examined the surficial morphological features of proximal tephra collected from Galunggung and Eyjafjalla volcanoes. Surface texture and morphology of volcanic ash particles change according to various

  2. Voluminous eruption from a zoned magma body after an increase in supply rate at Axial Seamount

    NASA Astrophysics Data System (ADS)

    Chadwick, W. W.; Paduan, J. B.; Clague, D. A.; Dreyer, B. M.; Merle, S. G.; Bobbitt, A. M.; Caress, D. W.; Philip, B. T.; Kelley, D. S.; Nooner, S. L.

    2016-12-01

    Axial Seamount is the best monitored submarine volcano in the world, providing an exceptional window into the dynamic interactions between magma storage, transport, and eruption processes in a mid-ocean ridge setting. An eruption in April 2015 produced the largest volume of erupted lava since monitoring and mapping began in the mid-1980s after the shortest repose time, due to a recent increase in magma supply. The higher rate of magma replenishment since 2011 resulted in the eruption of the most mafic lava in the last 500-600 years. Eruptive fissures at the volcano summit produced pyroclastic ash that was deposited over an area of at least 8 km2. A systematic spatial distribution of compositions is consistent with a single dike tapping different parts of a thermally and chemically zoned magma reservoir that can be directly related to previous multichannel seismic-imaging results.

  3. Seismic array observations for monitoring phreatic eruptions in Iwojima Island, Japan

    NASA Astrophysics Data System (ADS)

    Ueda, H.; Kawaguchi, R.; Chiba, K.; Fujita, E.; Tanada, T.

    2015-12-01

    Iwojima is an active volcanic island located within a 10 km wide submarine caldera about 1250 km to the south of Tokyo, Japan. The volcanic activity is characterized by intensive earthquake activity associated with an island-wide uplift with high uplift rate (30~40 cm/year) and hydrothermal activity. In the last 10 years, phreatic eruptions took place in and near the island in 2012, 2013, and 2015. In such restless volcano, predictions and detections of occurrence points of phreatic eruptions are important for ensuring safety of residents. In the previous studies, we found that the earthquake activity of Iwojima highly correlates with the island wide large uplift, but the precursory activity of the phreatic eruption in 2012 was deviated from the correlation (Ueda et al. 2013 AGU Fall Meeting). For prediction of occurrence points of phreatic eruptions and investigation of the eruption mechanism, we began observation by seismic arrays at two areas in December 2014. The seismic arrays enable to locate epicenters of volcanic tremors, which are not well located by existing seismic stations. In May and June 2015, Japan Maritime Self-Defense Force stayed in Iwojima and a live camera of Japan Meteorological Agency found very small phreatic eruptions occurred at the northern beach. Existing seismic stations could not detect seismic signals related with the eruptions. The seismic array could detect weak seismic signals related with the eruptions. Although the seismic arrays could not detect precursory signals because of too small eruption, we expect the seismic arrays can detect precursory seismic signals suggesting occurrence points of small or medium-sized phreatic eruptions. The seismic arrays also detected epicenters of harmonic and monotonic tremors took place at an active fumarolic field in the north earthen part of Iwojima. The apparent velocity of seismic waves (~1km/s) strongly suggests that the tremors relate with hydrothermal activity near ground surface.

  4. Eruptive history of South Sister, Oregon Cascades

    USGS Publications Warehouse

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

    2011-01-01

    South Sister is southernmost and highest of the Three Sisters, three geologically dissimilar stratovolcanoes that together form a spectacular 20km reach along the Cascade crest in Oregon. North Sister is a monotonously mafic edifice as old as middle Pleistocene, Middle Sister a basalt-andesite-dacite cone built between 48 and 14ka, and South Sister is a basalt-free edifice that alternated rhyolitic and intermediate modes from 50ka to 2ka (largely contemporaneous with Middle Sister). Detailed mapping, 330 chemical analyses, and 42 radioisotopic ages show that the oldest exposed South Sister lavas were initially rhyolitic ~50ka. By ~37ka, rhyolitic lava flows and domes (72-74% SiO2) began alternating with radially emplaced dacite (63-68% SiO2) and andesite (59-63% SiO2) lava flows. Construction of a broad cone of silicic andesite-dacite (61-64% SiO2) culminated ~30ka in a dominantly explosive sequence that began with crater-forming andesitic eruptions that left fragmental deposits at least 200m thick. This was followed at ~27ka by growth of a steeply dipping summit cone of agglutinate-dominated andesite (56-60.5% SiO2) and formation of a summit crater ~800m wide. This crater was soon filled and overtopped by a thick dacite lava flow and then by >150m of dacitic pyroclastic ejecta. Small-volume dacite lavas (63-67% SiO2) locally cap the pyroclastic pile. A final sheet of mafic agglutinate (54-56% SiO2) - the most mafic product of South Sister - erupted from and drapes the small (300-m-wide) present-day summit crater, ending a summit-building sequence that lasted until ~22ka. A 20kyr-long-hiatus was broken by rhyolite eruptions that produced (1) the Rock Mesa coulee, tephra, and satellite domelets (73.5% SiO2) and (2) the Devils Chain of ~20 domes and short coulees (72.3-72.8% SiO2) from N-S vent alignments on South Sister's flanks. The compositional reversal from mafic summit agglutinate to recent rhyolites epitomizes the frequently changing compositional modes of the

  5. Eruptive history of South Sister, Oregon Cascades

    NASA Astrophysics Data System (ADS)

    Fierstein, Judy; Hildreth, Wes; Calvert, Andrew T.

    2011-10-01

    South Sister is southernmost and highest of the Three Sisters, three geologically dissimilar stratovolcanoes that together form a spectacular 20 km reach along the Cascade crest in Oregon. North Sister is a monotonously mafic edifice as old as middle Pleistocene, Middle Sister a basalt-andesite-dacite cone built between 48 and 14 ka, and South Sister is a basalt-free edifice that alternated rhyolitic and intermediate modes from 50 ka to 2 ka (largely contemporaneous with Middle Sister). Detailed mapping, 330 chemical analyses, and 42 radioisotopic ages show that the oldest exposed South Sister lavas were initially rhyolitic ~ 50 ka. By ~ 37 ka, rhyolitic lava flows and domes (72-74% SiO 2) began alternating with radially emplaced dacite (63-68% SiO 2) and andesite (59-63% SiO 2) lava flows. Construction of a broad cone of silicic andesite-dacite (61-64% SiO 2) culminated ~ 30 ka in a dominantly explosive sequence that began with crater-forming andesitic eruptions that left fragmental deposits at least 200 m thick. This was followed at ~ 27 ka by growth of a steeply dipping summit cone of agglutinate-dominated andesite (56-60.5% SiO 2) and formation of a summit crater ~ 800 m wide. This crater was soon filled and overtopped by a thick dacite lava flow and then by > 150 m of dacitic pyroclastic ejecta. Small-volume dacite lavas (63-67% SiO 2) locally cap the pyroclastic pile. A final sheet of mafic agglutinate (54-56% SiO 2) - the most mafic product of South Sister - erupted from and drapes the small (300-m-wide) present-day summit crater, ending a summit-building sequence that lasted until ~ 22 ka. A 20 kyr-long-hiatus was broken by rhyolite eruptions that produced (1) the Rock Mesa coulee, tephra, and satellite domelets (73.5% SiO 2) and (2) the Devils Chain of ~ 20 domes and short coulees (72.3-72.8% SiO 2) from N-S vent alignments on South Sister's flanks. The compositional reversal from mafic summit agglutinate to recent rhyolites epitomizes the frequently

  6. 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.

  7. 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

  8. A conceptual model of the Mount Spurr magmatic system from seismic and geochemical observations of the 1992 Crater Peak eruption sequence

    USGS Publications Warehouse

    Power, J.; Jolly, A.; Nye, C.; Harbin, M.

    2002-01-01

    A conceptual model of the geometry and dynamics of the Mount Spurr magmatic system is developed using seismic, geochemical, and visual observations of the 1992 Crater Peak eruption sequence. The basis for this model is a new classification of all located seismic events and results from prior studies of seismology, geology, geochemistry, and geophysics of the Mount Spurr area. Significant seismic features of the 1992 eruption sequence include (1) a distinct swarm of volcano-tectonic (VT) earthquakes in August 1991 directly beneath the Crater Peak vent, (2) a caldera-wide increase in VT earthquakes, lasting 7 months, which preceded the 27 June eruption, (3) two shallow swarms of VT earthquakes that occured on 5 June and 27 June, the latter immediately preceding the 27 June eruption, (4) a mix of VT, long-period (LP), and hybrid events at depths of 20-40 km, which began coincident with the onset of seismic unrest and reached a peak after eruptive activity ended, (5) a strong swarm of VT earthquakes that began as the 16-17 September eruption was ending, (6) a prominent swarm of VT earthquakes on 9-10 November at depths of 1 to 4 km beneath Crater Peak, and (7) a smaller swarm of VT earthquakes in late December 1992, which were located between 7 and 10 km depth. These seismic observations, combined with geological, geochemical, and geophysical data and observations, suggest a deep magmatic source zone for Crater Peak andesites at depths of 20-40 km, a smaller mid-crustal storage zone at about 10 km depth, and a conduit that extends to the surface. We infer that the magmas erupted in 1992 were generated at depths of 20-40 km and rose to the mid-crustal storage zone that fed all three 1992 eruptions. The 1992 eruption sequence may have terminated when additional magma solidified at shallow depths.

  9. Long-range transport of SO2 over South Africa: A case study of the Calbuco volcanic eruption in April 2015

    NASA Astrophysics Data System (ADS)

    Sangeetha, S. K.; Sivakumar, V.; Gebreslasie, M.

    2018-07-01

    South Africa (SA) is influenced by anthropogenic SO2 emissions, however, no studies exist detailing the atmospheric or climatic effects resulting from volcanic eruptions at this location. In this work, the Calbuco volcano situated in southern Chile (41.79°S, 73.13°W), was used as a case study to investigate the transport of volcanic SO2 plumes over SA in 2015. The Calbuco volcano underwent a series of eruptive phases starting from 22 April 2015. In this study, HYSPLIT forward trajectories and cluster analysis were carried out in order to estimate the altitude level of air parcels entering the SA subcontinent. These analyses along with Ozone Monitoring Instrument (OMI) assessments confirmed that trajectories beginning in Calbuco arrived in SA during the last few days of April (∼28 April 2015) and stayed until the 1st week of May 2015 (∼2 May 2015). In order to estimate the rise in SO2 columnar concentrations at various altitudes and surface SO2 levels, OMI data and 19 ground-based (GB) monitoring stations (situated throughout SA) were utilized. A comparative analysis employing SO2 data from pre-2014 and post-2016 volcanic eruption periods were also included in this study. Results showed that a major increase in SO2 concentration was observed at the Planetary Boundary Layer (∼ 2 DU) when compared to its upper layers during April and May 2015. Although some GB stations in North West province namely Damonsville, Mmabatho and Phola showed a moderate increase in SO2 values during April and May 2015, there was no significant rise in GB measurements at the surface in other locations However, we are not certain due to data gaps in the measurements and non-availability of ground-based measurements.

  10. Small volcanic eruptions and the stratospheric sulfate aerosol burden

    NASA Astrophysics Data System (ADS)

    Pyle, David M.

    2012-09-01

    (Rampino and Self 1984, Pyle et al 1996, Self and Rampino 2012). But as yet, there is little evidence for the consequences of this scale of eruption for the climate system (Miles et al 2004), and few data against which to test simulations of stratospheric sulfur-injection 'geoengineering' scenarios of a similar scale and frequency (e.g. English et al 2012). A hint of the new volcano-observing capability came during the eruption of Eyjafjallajökull, Iceland. For a few days in April 2010 meteorological conditions, coupled with a dramatic increase in volcanic ash production, led to the wide dispersal of fine volcanic particles across northern Europe; an event which was widely tracked by ground-based and satellite-borne instruments, augmented by in situ measurements from balloons and aircraft (Bennett et al 2010, Flentje et al 2010, Harrison et al 2010, Stohl et al 2011). Despite the interest in Eyjafjallajökull at the time, this was, geologically, only a very modest eruption with limited sulfur emissions and an impact restricted mainly to the regional troposphere (e.g. Thomas and Prata 2011, Walker et al 2012). Then, in June 2011, a previously dormant volcano in north-east Africa began to erupt violently. Little is known about Nabro, which is a partially collapsed volcano that straddles the Eritrea-Ethiopia border, and has had no known historical activity (Wiart and Oppenheimer 2005). Despite the remote location, and lack of prior warning, the event and its aftermath were remarkably well captured by remote-sensing instruments, as demonstrated in the new letter by Sawamura et al (2012). Using both ground-based and satellite-borne laser-ranging (lidar) data, Sawamura et al (2012) were able to extract detailed information about the nature of the volcanic aerosol layer, and its spread around the globe. The eruption started strongly, with substantial ash plumes for the first 48 h, rising to 9-14 km altitude (Smithsonian Institution 2011, Bourassa et al 2012), that carried at

  11. Waveform Template Matching and Analysis of Hydroacoustic Events from the April-May 2015 Eruption of Axial Volcano

    NASA Astrophysics Data System (ADS)

    Mann, M. E.; Bohnenstiehl, D. R.; Weis, J.

    2016-12-01

    The submarine emplacement of new lava flows during the 2015 eruption of Axial Volcano generated a series of impulsive acoustic signals that were captured by seismic and hydrophone sensors deployed as part of the Ocean Observatories Initiative cabled array network. A catalog of >37,000 explosions was created using a four-channel waveform matching routine using 800 template arrivals. Most of the explosions are sourced from a set of lava mounds erupted along the volcano's northern rift; however, a subset of 400 explosions are located within the caldera and track the flow of lava from a vent near its eastern rim. The earliest explosion occurs at 08:00 UTC on April 24, approximately four hours after the seismicity rate began to increase and two hours after bottom pressure recorders indicate the caldera floor began to subside. Between April 24 and 28 event rates are sustained at 1000/day. The rate then decreases gradually with explosive activity ending on 21 May, coincident with the initial re-inflation of the caldera. The windowed coefficient of variation of the inter-event time is approximately 1 throughout the eruption, consistent with a random process. The size-frequency distribution shows a bimodal pattern, with the loudest explosions, having received levels up to 157 dB re 1 micro-Pa, being produced during the first few hours of the eruption.

  12. A volcano bursting at the seams: Inflation, faulting, and eruption at Sierra Negra volcano, Galápagos

    USGS Publications Warehouse

    Chadwick, William W.; Geist, Dennis J.; Jonsson, Sigurjon; Poland, Michael P.; Johnson, Daniel J.; Meertens, Charles M.

    2006-01-01

    The results of geodetic monitoring since 2002 at Sierra Negra volcano in the Galápagos Islands show that the filling and pressurization of an ∼2-km-deep sill eventually led to an eruption that began on 22 October 2005. Continuous global positioning system (CGPS) monitoring measured >2 m of accelerating inflation leading up to the eruption and contributed to nearly 5 m of total uplift since 1992, the largest precursory inflation ever recorded at a basaltic caldera. This extraordinary uplift was accommodated in part by repeated trapdoor faulting, and coseismic CGPS data provide strong constraints for improved deformation models. These results highlight the feedbacks between inflation, faulting, and eruption at a basaltic volcano, and demonstrate that faulting above an intruding magma body can relieve accumulated strain and effectively postpone eruption.

  13. Climate response to the Samalas volcanic eruption in 1257 revealed by proxy records

    NASA Astrophysics Data System (ADS)

    Guillet, Sébastien; Corona, Christophe; Stoffel, Markus; Khodri, Myriam; Lavigne, Franck; Ortega, Pablo; Eckert, Nicolas; Sielenou, Pascal Dkengne; Daux, Valérie; Churakova (Sidorova), Olga V.; Davi, Nicole; Edouard, Jean-Louis; Zhang, Yong; Luckman, Brian H.; Myglan, Vladimir S.; Guiot, Joël; Beniston, Martin; Masson-Delmotte, Valérie; Oppenheimer, Clive

    2017-01-01

    The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the Common Era with sulfur deposition in ice cores reaching twice the volume of the Tambora eruption in 1815. Sedimentological analyses of deposits confirm the exceptional size of the event, which had both an eruption magnitude and a volcanic explosivity index of 7. During the Samalas eruption, more than 40 km3 of dense magma was expelled and the eruption column is estimated to have reached altitudes of 43 km. However, the climatic response to the Samalas event is debated since climate model simulations generally predict a stronger and more prolonged surface air cooling of Northern Hemisphere summers than inferred from tree-ring-based temperature reconstructions. Here, we draw on historical archives, ice-core data and tree-ring records to reconstruct the spatial and temporal climate response to the Samalas eruption. We find that 1258 and 1259 experienced some of the coldest Northern Hemisphere summers of the past millennium. However, cooling across the Northern Hemisphere was spatially heterogeneous. Western Europe, Siberia and Japan experienced strong cooling, coinciding with warmer-than-average conditions over Alaska and northern Canada. We suggest that in North America, volcanic radiative forcing was modulated by a positive phase of the El Niño-Southern Oscillation. Contemporary records attest to severe famines in England and Japan, but these began prior to the eruption. We conclude that the Samalas eruption aggravated existing crises, but did not trigger the famines.

  14. Phreatic eruptions and deformation of Ioto Island (Iwo-jima), Japan, triggered by deep magma injection

    NASA Astrophysics Data System (ADS)

    Ueda, Hideki; Nagai, Masashi; Tanada, Toshikazu

    2018-03-01

    On Ioto Island (Iwo-jima), 44 phreatic eruptions have been recorded since 1889, when people began to settle there. Four of these eruptions, after the beginning of continuous observation by seismometers in 1976, were accompanied by intense seismic activity and rapid crustal deformation beforehand. Other eruptions on Ioto were without obvious crustal activities. In this paper, we discuss the mechanisms of phreatic eruptions on Ioto. Regular geodetic surveys and continuous GNSS observations show that Ioto intermittently uplifts at an abnormally high rate. All of the four eruptions accompanied by the precursors took place during intermittent uplifts. The crustal deformation before and after one of these eruptions revealed that a sill-like deformation source in the shallow part of Motoyama rapidly inflated before and deflated after the beginning of the eruption. From the results of a seismic array and a borehole survey, it is estimated that there is a layer of lava at a depth of about 100-200 m, and there is a tuff layer about 200-500 m beneath it. The eruptions accompanied by the precursors probably occurred due to abrupt boiling of hot water in hydrothermal reservoirs in the tuff layer, sealed by the lava layer and triggered by intermittent uplift. For the eruptions without precursors, the hydrothermal systems are weakly sealed by clay or probably occurred on the same principle as a geyser because phreatic eruptions had occurred beforehand and hydrostatic pressure is applied to the hydrothermal reservoirs.

  15. 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

  16. Video and seismic observations of Strombolian eruptions at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Dibble, R. R.; Kyle, P. R.; Rowe, C. A.

    2008-11-01

    Between 1986 and 1990 the eruptive activity of Erebus volcano was monitored by a video camera with on-screen time code and recorded on video tape. Corresponding seismic and acoustic signals were recorded from a network of 6 geophones and 2 infrasonic microphones. Two hundred Strombolian explosions and three lava flows which were erupted from 7 vents were captured on video. In December 1986 the Strombolian eruptions ejected bombs and ash. In November 1987 large bubble-bursting Strombolian eruptions were observed. The bubbles burst when the bubble walls thinned to ˜ 20 cm. Explosions with bomb flight-times up to 14.5 s were accompanied by seismic signals with our local size estimate, "unified magnitudes" ( mu), up to 2.3. Explosions in pools of lava formed by flows in the Inner Crater were comparatively weak. Changes in eruptive activity occurred in 1987 when the lava lake was buried by a landslide from the crater wall. Two new vents formed and seismic activity peaked as the landslide was ingested. Lava flows from a vent on the eastern side of the crater formed small lakes and a vent on the north began to flow in 1990. By December 1990 the entire floor of the Inner Crater was buried by up to 20 000 m 3 of new lava. Different families of nearly identical eruption earthquakes occurred each year, whose foci were contained within small, shallow volumes. Immediately after several bubble-bursting eruptions, clear views of the empty vent were recorded. The vent was seen to taper downwards to about half its diameter at the bottom. Our observations confirm models of Strombolian eruptions suggesting they arise from gas slugs rising through a conduit into a flared vent.

  17. Volcanomagnetic signals during the recent Popocatépetl (México) eruptions and their relation to eruptive activity

    NASA Astrophysics Data System (ADS)

    Martin-Del Pozzo, A. L.; Cifuentes-Nava, G.; Cabral-Cano, E.; Sánchez-Rubio, G.; Reyes, M.; Martínez-Bringas, Alicia; Garcia, E.; Arango-Galvan, C.

    2002-03-01

    An interdisciplinary approach correlating magnetic anomalies with composition of the ejecta in each eruption, as well as with seismicity, was used to study the effect of magmatic activity on the local magnetic record at Popocatépetl Volcano located 65 km southeast of México City. Eruptions began on December, 1994, and have continued with dome growth and ash emissions since then. The Tlamacas (TLA) geomagnetic total field monitoring station, located 5 km away from Popocatépetl's crater, was installed in December, 1997, in order to detect magnetic anomalies induced by this activity. Spatial correlation and weighted difference methods were applied to detect temporal geomagnetic anomalies using TLA's record and the Teoloyucan Magnetic Observatory as a reference station. Weighted differences were applied to cancel the effects of non-vulcanogenic external field variations. Magnetic anomalies over a 2-year time span were classified into four types correlating them with geochemical, seismic and visual monitoring of the volcanic activity. Magnetic anomalies are believed to be caused by magma injection and gas pressure build-up, which is sensitive to vent morphology and clearing during eruption, although some anomalies appear to be thermally related, changes in the stress field are very important. Most magnetic anomalies are short time signals that reverse to baseline level. Decreasing anomalies (-0.5 to -6.8 nT) precede eruptions by 1-8 days. The presence of a mafic magmatic component was determined by mineral examination and silica and magnesium analyses on the ejecta from the 1997-1999 eruptions. Whole rock analyses ranged from dacitic (65% SiO 2) to andesitic (57% SiO 2) with 2-6.6% MgO. The higher MgO, lower silica samples contain forsteritic olivine (Fo90). SiO 2 does not increase and MgO does not increase with time, suggesting ascent of small magma pulses which are consistent with the magnetic data.

  18. Eruption history of the Tharsis shield volcanoes, Mars

    NASA Technical Reports Server (NTRS)

    Plescia, J. B.

    1993-01-01

    The Tharsis Montes volcanoes and Olympus Mons are giant shield volcanoes. Although estimates of their average surface age have been made using crater counts, the length of time required to build the shields has not been considered. Crater counts for the volcanoes indicate the constructs are young; average ages are Amazonian to Hesperian. In relative terms; Arsia Mons is the oldest, Pavonis Mons intermediate, and Ascreaus Mons the youngest of the Tharsis Montes shield; Olympus Mons is the youngest of the group. Depending upon the calibration, absolute ages range from 730 Ma to 3100 Ma for Arsia Mons and 25 Ma to 100 Ma for Olympus Mons. These absolute chronologies are highly model dependent, and indicate only the time surficial volcanism ceased, not the time over which the volcano was built. The problem of estimating the time necessary to build the volcanoes can be attacked in two ways. First, eruption rates from terrestrial and extraterrestrial examples can be used to calculate the required period of time to build the shields. Second, some relation of eruptive activity between the volcanoes can be assumed, such as they all began at a speficic time or they were active sequentially, and calculate the eruptive rate. Volumes of the shield volcanoes were derived from topographic/volume data.

  19. Low intensity hawaiian fountaining as exemplified by the March 2011, Kamoamoa eruption at Kilauea Volcano, Hawai`i (Invited)

    NASA Astrophysics Data System (ADS)

    Orr, T. R.; Houghton, B. F.; Poland, M. P.; Patrick, M. R.; Thelen, W. A.; Sutton, A. J.; Parcheta, C. E.; Thornber, C. R.

    2013-12-01

    The latest 'classic' hawaiian high-fountaining activity at Kilauea Volcano occurred in 1983-1986 with construction of the Pu`u `O`o pyroclastic cone. Since then, eruptions at Kilauea have been dominated by nearly continuous effusive activity. Episodes of sustained low hawaiian fountaining have occurred but are rare and restricted to short-lived fissure eruptions along Kilauea's east rift zone. The most recent of these weakly explosive fissure eruptions--the Kamoamoa eruption--occurred 5-9 March 2011. The Kamoamoa eruption was probably the consequence of a decrease in the carrying capacity of the conduit feeding the episode 58 eruptive vent down-rift from Pu`u `O`o in Kilauea's east rift zone. As output from the vent waned, Kilauea's summit magma storage and east rift zone transport system began to pressurize, as manifested by an increase in seismicity along the upper east rift zone, inflation of the summit and Pu`u `O`o, expansion of the east rift zone, and rising lava levels at both the summit and Pu`u `O`o. A dike began propagating towards the surface from beneath Makaopuhi Crater, 6 km west of Pu`u `O`o, at 1342 Hawaiian Standard Time (UTC - 10 hours) on 5 March. A fissure eruption started about 3.5 hours later near Nāpau Crater, 2 km uprift of Pu`u `O`o. Activity initially jumped between numerous en echelon fissure segments before centering on discrete vents near both ends of the 2.4-km-long fissure system for the final two days of the eruption. About 2.6 mcm of lava was erupted over the course of four days with a peak eruption rate of 11 m3/s. The petrologic characteristics of the fissure-fed lava indicate mixing between hotter mantle-derived magma and cooler rift-stored magma, with a greater proportion of the cooler component than was present in east rift zone lava erupting before March 2011. The fissure eruption was accompanied by the highest SO2 emission rates since 1986. Coincidentally, the summit and Pu`u `O`o deflated as magma drained away, causing

  20. Locating the depth of magma supply for volcanic eruptions, insights from Mt. Cameroon

    PubMed Central

    Geiger, Harri; Barker, Abigail K.; Troll, Valentin R.

    2016-01-01

    Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano’s underlying magma supply system is sparse. To characterize Mt. Cameroon’s magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano’s two most recent eruptions of 1999 and 2000. Our results suggest pre-eruptive magma storage between 20 and 39 km beneath Mt. Cameroon, which corresponds to the Moho level and below. Additionally, the 1999 eruption products reveal several shallow magma pockets between 3 and 12 km depth, which are not detected in the 2000 lavas. This implies that small-volume magma batches actively migrate through the plumbing system during repose intervals. Evolving and migrating magma parcels potentially cause temporary unrest and short-lived explosive outbursts, and may be remobilized during major eruptions that are fed from sub-Moho magma reservoirs. PMID:27713494

  1. Locating the depth of magma supply for volcanic eruptions, insights from Mt. Cameroon.

    PubMed

    Geiger, Harri; Barker, Abigail K; Troll, Valentin R

    2016-10-07

    Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano's underlying magma supply system is sparse. To characterize Mt. Cameroon's magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano's two most recent eruptions of 1999 and 2000. Our results suggest pre-eruptive magma storage between 20 and 39 km beneath Mt. Cameroon, which corresponds to the Moho level and below. Additionally, the 1999 eruption products reveal several shallow magma pockets between 3 and 12 km depth, which are not detected in the 2000 lavas. This implies that small-volume magma batches actively migrate through the plumbing system during repose intervals. Evolving and migrating magma parcels potentially cause temporary unrest and short-lived explosive outbursts, and may be remobilized during major eruptions that are fed from sub-Moho magma reservoirs.

  2. The 2005 eruption of Sierra Negra volcano, Galápagos, Ecuador

    USGS Publications Warehouse

    Geist, Dennis J.; Harpp, Karen S.; Naumann, Terry R.; Poland, Michael P.; Chadwick, William W.; Hall, Minard; Rader, Erika

    2008-01-01

    Sierra Negra volcano began erupting on 22 October 2005, after a repose of 26 years. A plume of ash and steam more than 13 km high accompanied the initial phase of the eruption and was quickly followed by a ~2-km-long curtain of lava fountains. The eruptive fissure opened inside the north rim of the caldera, on the opposite side of the caldera from an active fault system that experienced an mb 4.6 earthquake and ~84 cm of uplift on 16 April 2005. The main products of the eruption were an `a`a flow that ponded in the caldera and clastigenic lavas that flowed down the north flank. The `a`a flow grew in an unusual way. Once it had established most of its aerial extent, the interior of the flow was fed via a perched lava pond, causing inflation of the `a`a. This pressurized fluid interior then fed pahoehoe breakouts along the margins of the flow, many of which were subsequently overridden by `a`a, as the crust slowly spread from the center of the pond and tumbled over the pahoehoe. The curtain of lava fountains coalesced with time, and by day 4, only one vent was erupting. The effusion rate slowed from day 7 until the eruption’s end two days later on 30 October. Although the caldera floor had inflated by ~5 m since 1992, and the rate of inflation had accelerated since 2003, there was no transient deformation in the hours or days before the eruption. During the 8 days of the eruption, GPS and InSAR data show that the caldera floor deflated ~5 m, and the volcano contracted horizontally ~6 m. The total eruptive volume is estimated as being ~150×106 m3. The opening-phase tephra is more evolved than the eruptive products that followed. The compositional variation of tephra and lava sampled over the course of the eruption is attributed to eruption from a zoned sill that lies 2.1 km beneath the caldera floor.

  3. The Sulfur Dioxide Plume from the February 26, 2000 Eruption of Mt. Hekla, Iceland

    NASA Technical Reports Server (NTRS)

    Krueger, Arlin J.; Krotkov, N. A.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The February 2000 fissure eruption of Mt. Hekla, Iceland was captured in sulfur dioxide data from the Earth Probe TOMS. A special algorithm is used to discriminate sulfur dioxide from ozone. The eruption began at 18:19 GMT on February 26, 2000 and was first viewed by TOMS at 09:55 GMT on February 27. The volcanic cloud at that time appeared as a very long and narrow arc extending west from the volcano in southern Iceland, then north across Greenland, and finally east towards Norway. The cloud altitude was reported from aircraft sightings and data to be above 10 km. The circulation of a ridge located north of Iceland produced the large arc shaped cloud. As the eruption is non-explosive the high altitude cloud contains little ash. Almost all the ash from the eruption fell out locally across Iceland. By February 29, the sulfur dioxide cloud had drifted eastward in a band along the Barents Sea coast of Norway and Russia. The analysis includes an assessment of the initial sulfur dioxide content and its rate of conversion to sulfate.

  4. 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

  5. The Pu'u 'O'o-Kupaianaha Eruption of Kilauea Volcano, Hawaii: The First 20 Years

    USGS Publications Warehouse

    Heliker, Christina C.; Swanson, Donald A.; Takahashi, Taeko Jane

    2003-01-01

    The Pu'u 'O'o-Kupaianaha eruption started on January 3, 1983. The ensuing 20-year period of nearly continuous eruption is the longest at Kilauea Volcano since the famous lava-lake activity of the 19th century. No rift-zone eruption in more than 600 years even comes close to matching the duration and volume of activity of these past two decades. Fortunately, such a landmark event came during a period of remarkable technological advancements in volcano monitoring. When the eruption began, the Global Positioning System (GPS) and the Geographic Information System (GIS) were but glimmers on the horizon, broadband seismology was in its infancy, and the correlation spectrometer (COSPEC), used to measure SO2 flux, was still very young. Now, all of these techniques are employed on a daily basis to track the ongoing eruption and construct models about its behavior. The 12 chapters in this volume, written by present or past Hawaiian Volcano Observatory staff members and close collaborators, celebrate the growth of understanding that has resulted from research during the past 20 years of Kilauea's eruption. The chapters range widely in emphasis, subject matter, and scope, but all present new concepts or important modifications of previous ideas - in some cases, ideas long held and cherished.

  6. Nicaragua Eruption Lava Threat Closely Monitored by NASA EO-1 Spacecraft

    NASA Image and Video Library

    2015-12-07

    Momotombo volcano, Nicaragua, began erupting on Dec. 1, 2015, after more than a century of inactivity. On Dec. 4, 2015, the Advanced Land Imager (ALI) on NASA's Earth Observing 1 (EO-1) spacecraft observed the new eruption. This image is created from infrared data, and shows the incandescent active vent at the summit of the volcano and lava flowing down the side of the volcano. These data are being examined by scientists to determine where lava will flow, allowing assessment of possible threats to local infrastructure. The EO-1 data were obtained at an altitude of 438 miles (705 kilometers) and at a resolution of 98 feet (30 meters) per pixel at different visible and infrared wavelengths. The ALI image is 23 miles (37 kilometers) wide. http://photojournal.jpl.nasa.gov/catalog/PIA20203

  7. NASA AIRS Instrument Tracks Transport of Sulfur Dioxide from Chilean Volcanic Eruption Animation

    NASA Image and Video Library

    2015-05-07

    For the first time in 40 years, the Calbuco volcano in southern Chile erupted on April 22, 2015. The eruption caused airline flight cancellations in Chile, Argentina and Uruguay and the evacuation of approximately 4,000 people. This movie shows alternating day and nighttime views of the plume of sulfur dioxide gas emitted by Calbuco, as observed by NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft, from April 22 to May 5, 2015. Significant amounts of sulfur dioxide are shown in bright red. The largest plume is apparent over South America during the initial eruption on April 22. The plume is then carried by winds across the south Atlantic Ocean and southern Africa. A second large eruption on April 29 produced a smaller plume. Volcanic sulfur dioxide can be an important factor in climate. Some of it is carried into Earth's stratosphere, where it is transformed into highly reflective droplets of sulfuric acid. By reflecting sunlight, these droplets can cool Earth. Large eruptions, like Mt. Pinatubo in 1991, cool our planet and disrupt rainfall patterns. Though an impressive eruption, Calbuco is expected to have only a small impact on Earth's climate. http://photojournal.jpl.nasa.gov/catalog/PIA19385

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

    USGS Publications Warehouse

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

    2000-01-01

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

  9. Constraining magma physical properties and its temporal evolution from InSAR and topographic data only: a physics-based eruption model for the effusive phase of the Cordon Caulle 2011-2012 rhyodacitic eruption

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Kubanek, J.; Anderson, K. R.; Lundgren, P.; Pritchard, M. E.

    2017-12-01

    The 2011-2012 eruption of Cordón Caulle volcano in Chile is the best scientifically observed rhyodacitic eruption and is thus a key place to understand the dynamics of these rare but powerful explosive rhyodacitic eruptions. Because the volatile phase controls both the eruption temporal evolution and the eruptive style, either explosive or effusive, it is important to constrain the physical parameters that drive these eruptions. The eruption began explosively and after two weeks evolved into a hybrid explosive - lava flow effusion whose volume-time evolution we constrain with a series of TanDEM-X Digital Elevation Models. Our data shows the intrusion of a large volume laccolith or cryptodome during the first 2.5 months of the eruption and lava flow effusion only afterwards, with a total volume of 1.4 km3. InSAR data from the ENVISAT and TerraSAR-X missions shows more than 2 m of subsidence during the effusive eruption phase produced by deflation of a finite spheroidal source at a depth of 5 km. In order to constrain the magma total H2O content, crystal cargo, and reservoir pressure drop we numerically solve the coupled set of equations of a pressurized magma reservoir, magma conduit flow and time dependent density, volatile exsolution and viscosity that we use to invert the InSAR and topographic data time series. We compare the best-fit model parameters with independent estimates of magma viscosity and total gas content measured from lava samples. Preliminary modeling shows that although it is not possible to model both the InSAR and the topographic data during the onset of the laccolith emplacement, it is possible to constrain the magma H2O and crystal content, to 4% wt and 30% which agree well with published literature values.

  10. Deformation Associated With the July 21 Fissure Eruption at Kilauea Volcano, Hawai`i

    NASA Astrophysics Data System (ADS)

    Poland, M.; Orr, T.; Miklius, A.

    2007-12-01

    Deformation measurements at the Pu`u `O`o cone on Kilauea volcano indicate that the vent is underlain by a shallow magma storage reservoir fed by magma transported from Kilauea's summit. The Pu`u `O`o reservoir was drained during the "Father's&pDay" intrusion of June 17-19, 2007, causing Pu`u `O`o's floor to collapse. Following the intrusion, the reservoir gradually refilled and lava reappeared on July 1-2. A lava lake grew in the crater during July 2-20, steadily raising the elevation of the crater floor. The crater interior and adjoining walls began to uplift on July 10, and 2 days later lava began to vent above the level of the lava lake along the margins of the crater. The number of crater margin vents and the magnitude of their activity increased until July 21, by which time crater uplift amounted to about 8 meters. Early that morning, the lava pond at Pu`u `O`o drained suddenly and an eruptive fissure opened on the east flank of the cone. The fissure propagated 2 km downrift, and within a few hours the eruption had localized on three fissure segments between 1 and 2 km east of Pu`u `O`o. Lava erupting from this series of vents formed a system of perched lava ponds feeding long `a`a flows. Deformation associated with the July 21 fissure was exceptionally well-documented by a borehole tiltmeter on the north flank of Pu`u `O`o and 7 continuous GPS stations within 2 km of the cone (the fissure propagated between two of these GPS stations). The time series of geodetic measurements suggests that deflation of Pu`u `O`o began at about 2250 HST (Hawaiian Standard Time - UTC minus 10 hours) on July 20, while a camera looking into Pu`u `O`o crater recorded draining of the lava lake starting at around 2355 HST. Deformation associated with opening of the fissure was apparent in the tilt and GPS records by 0012 HST, with the camera showing glow in the direction of the eruption site by 0039 HST on July 21. Localized deformation from InSAR suggests that the fissure has a

  11. NASA's MISR Spots Alaskan Volcano's Latest Eruption

    NASA Image and Video Library

    2017-06-02

    The tiny Aleutian island of Bogoslof in Alaska, erupting regularly since December 2016, produced fresh activity on Sunday, May 28, 2017. Bogoslof is a stratovolcano fueled by the subduction of the Pacific Plate under the North American Plate and forms part of the larger Aleutian Arc, which includes more than 60 volcanoes on the Aleutian Islands and the Aleutian Range on the Alaska mainland. Previous to its recent period of activity, Bogoslof had last erupted in 1992, and its above-water surface area was a mere 0.11 square miles (0.29 square kilometers). As of March 11, the most recent data available, the area of the island had tripled to 0.38 square miles (0.98 square kilometers). The event on May 28 produced an ash cloud that reached 40,000 feet (12 km) in altitude, causing the Alaskan Volcano Observatory to issue a red alert for air travel in the area. Volcanic ash can cause major damage to aircraft engines, and the region is close to several major air routes between North America and Asia. On May 28, 2017, at approximately 2:23 p.m. local time, NASA's Terra satellite passed over Bogoslof, less than 10 minutes after the eruption began. MISR has nine cameras that view Earth at different angles. It takes slightly less than seven minutes for all nine cameras to view the same location on Earth. An animation made from the images from the nine MISR cameras, captured between 2:19 and 2:26 p.m., demonstrates how the angled views give a glimpse of the underside of the growing plume of volcanic ash, showing the eruption column widening into the cloud at the top. The animation is available at https://photojournal.jpl.nasa.gov/catalog/PIA21655

  12. The First Historical Eruption of Kambalny Volcano in 2017 .

    NASA Astrophysics Data System (ADS)

    Gordeev, E.

    2017-12-01

    The first historical eruption at Kambalny volcano began about 21:20 UTC on March 24, 2017 with powerful ash emissions up to 6 km above sea level from the pre-summit crater. According to tephrochronological data, it is assumed that the strong eruptions of the volcano occurred 200 (?) and 600 years ago. KVERT (Kamchatka Volcanic Eruption Response Team) of the Institute of Volcanology and Seismology FEB RAS has been monitoring Kambalny volcano since 2002. KVERT worked closely with AMC Elizovo and Tokyo VAAC during the eruption at Kambalny volcano in 2017. The maximum intensity of ash emissions occurred on 25-26 March: a continuous plume laden with ash particles spread over several thousand kilometers, changing the direction of propagation from the volcano from the south-west to the south and south-east. On 27-29 March, the ash plume extended to the west, on 30 March - to the southeast of the volcano. On March 31 and April 01, the volcano was relatively quiet. The resumption of the volcano activity after two days of rest was expressed in powerful ash emissions up to 7 km above sea level. Gas-steam plumes containing some amount of ash were noted on 02-05 April, and powerful ash emissions up to 7 km above sea level occurred on 09 April. The explosive activity at the volcano ended on 11 April. The area of ash deposits was about 1500 km2, the total area covered by ash falls, for example, on 25 March, was about 650 thousand km2. To monitor and study the Kambalny volcano eruption we mainly used satellite images of medium resolution available in the information system "Monitoring volcanic activity in Kamchatka and Kurile Islands" (VolSatView). This work was supported by the Russian Science Foundation, project No. 16-17-00042.

  13. Kamchatka and North Kurile Volcano Explosive Eruptions in 2015 and Danger to Aviation

    NASA Astrophysics Data System (ADS)

    Girina, Olga; Melnikov, Dmitry; Manevich, Alexander; Demyanchuk, Yury; Nuzhdaev, Anton; Petrova, Elena

    2016-04-01

    There are 36 active volcanoes in the Kamchatka and North Kurile, and several of them are continuously active. In 2015, four of the Kamchatkan volcanoes (Sheveluch, Klyuchevskoy, Karymsky and Zhupanovsky) and two volcanoes of North Kurile (Alaid and Chikurachki) had strong and moderate explosive eruptions. Moderate gas-steam activity was observing of Bezymianny, Kizimen, Avachinsky, Koryaksky, Gorely, Mutnovsky and other volcanoes. Strong explosive eruptions of volcanoes are the most dangerous for aircraft because they can produce in a few hours or days to the atmosphere and the stratosphere till 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 2015: on 07, 12, and 15 January, 01, 17, and 28 February, 04, 08, 16, 21-22, and 26 March, 07 and 12 April: ash plumes rose up to 7-12 km a.s.l. and extended more 900 km to the different directions of the volcano. Ashfalls occurred at Ust'-Kamchatsk on 16 March, and Klyuchi on 30 October. Strong and moderate hot avalanches from the lava dome were observing more often in the second half of the year. Aviation color code of Sheveluch was Orange during the year. Activity of the volcano was dangerous to international and local aviation. Explosive-effusive eruption of Klyuchevskoy volcano lasted from 01 January till 24 March. Strombolian explosive volcanic activity began from 01 January, and on 08-09 January a lava flow was detected at the Apakhonchich chute on the southeastern flank of the volcano. Vulcanian activity of the volcano began from 10 January. Ashfalls

  14. An overview of the 2009 eruption of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Bull, Katharine F.; Buurman, Helena

    2013-06-01

    In March 2009, Redoubt Volcano, Alaska erupted for the first time since 1990. Explosions ejected plumes that disrupted international and domestic airspace, sent lahars more than 35 km down the Drift River to the coast, and resulted in tephra fall on communities over 100 km away. Geodetic data suggest that magma began to ascend slowly from deep in the crust and reached mid- to shallow-crustal levels as early as May, 2008. Heat flux at the volcano during the precursory phase melted ~ 4% of the Drift glacier atop Redoubt's summit. Petrologic data indicate the deeply sourced magma, low-silica andesite, temporarily arrested at 9-11 km and/or at 4-6 km depth, where it encountered and mixed with segregated stored high-silica andesite bodies. The two magma compositions mixed to form intermediate-silica andesite, and all three magma types erupted during the earliest 2009 events. Only intermediate- and high-silica andesites were produced throughout the explosive and effusive phases of the eruption. The explosive phase began with a phreatic explosion followed by a seismic swarm, which signaled the start of lava effusion on March 22, shortly prior to the first magmatic explosion early on March 23, 2009 (UTC). More than 19 explosions (or “Events”) were produced over 13 days from a single vent immediately south of the 1989-90 lava domes. During that period multiple small pyroclastic density currents flowed primarily to the north and into glacial ravines, three major lahars flooded the Drift River Terminal over 35 km down-river on the coast, tephra fall deposited on all aspects of the edifice and on several communities north and east of the volcano, and at least two, and possibly three lava domes were emplaced. Lightning accompanied almost all the explosions. A shift in the eruptive character took place following Event 9 on March 27 in terms of infrasound signal onsets, the character of repeating earthquakes, and the nature of tephra ejecta. More than nine additional

  15. Eruptions of Hawaiian volcanoes - Past, present, and future

    USGS Publications Warehouse

    Tilling, Robert I.; Heliker, Christina; Swanson, Donald A.

    2010-01-01

    Viewing an erupting volcano is a memorable experience, one that has inspired fear, superstition, worship, curiosity, and fascination since before the dawn of civilization. In modern times, volcanic phenomena have attracted intense scientific interest, because they provide the key to understanding processes that have created and shaped more than 80 percent of the Earth's surface. The active Hawaiian volcanoes have received special attention worldwide because of their frequent spectacular eruptions, which often can be viewed and studied with relative ease and safety. In January 1987, the Hawaiian Volcano Observatory (HVO), located on the rim of Kilauea Volcano, celebrated its 75th Anniversary. In honor of HVO's Diamond Jubilee, the U.S. Geological Survey (USGS) published Professional Paper 1350 (see list of Selected Readings, page 57), a comprehensive summary of the many studies on Hawaiian volcanism by USGS and other scientists through the mid-1980s. Drawing from the wealth of data contained in that volume, the USGS also published in 1987 the original edition of this general-interest booklet, focusing on selected aspects of the eruptive history, style, and products of two of Hawai'i's active volcanoes, Kilauea and Mauna Loa. This revised edition of the booklet-spurred by the approaching Centennial of HVO in January 2012-summarizes new information gained since the January 1983 onset of Kilauea's Pu'u 'O'o-Kupaianaha eruption, which has continued essentially nonstop through 2010 and shows no signs of letup. It also includes description of Kilauea's summit activity within Halema'uma'u Crater, which began in mid-March 2008 and continues as of this writing (late 2010). This general-interest booklet is a companion to the one on Mount St. Helens Volcano first published in 1984 and revised in 1990 (see Selected Readings). Together, these publications illustrate the contrast between the two main types of volcanoes: shield volcanoes, such as those in Hawai'i, which generally

  16. Investigating Preschool Education and Care in South Africa.

    ERIC Educational Resources Information Center

    Van Den Berg, Owen C.; Vergnani, Tania

    Recognizing the complexities of apartheid with its implications for conducting systems-related research within the vortex of South Africa, a study investigated the implementation of a national system of preschool provision for South Africa. The investigation began by studying two earlier reports: the Reilly-Hofmeyr report of 1983 and the report of…

  17. MULTIWAVELENGTH OBSERVATIONS OF A SLOW-RISE, MULTISTEP X1.6 FLARE AND THE ASSOCIATED ERUPTION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yurchyshyn, V.; Kumar, P.; Cho, K.-S.

    Using multiwavelength observations, we studied a slow-rise, multistep X1.6 flare that began on 2014 November 7 as a localized eruption of core fields inside a δ-sunspot and later engulfed the entire active region (AR). This flare event was associated with formation of two systems of post-eruption arcades (PEAs) and several J-shaped flare ribbons showing extremely fine details, irreversible changes in the photospheric magnetic fields, and it was accompanied by a fast and wide coronal mass ejection. Data from the Solar Dynamics Observatory and IRIS spacecraft, along with the ground-based data from the New Solar Telescope, present evidence that (i) themore » flare and the eruption were directly triggered by a flux emergence that occurred inside a δ-sunspot at the boundary between two umbrae; (ii) this event represented an example of the formation of an unstable flux rope observed only in hot AIA channels (131 and 94 Å) and LASCO C2 coronagraph images; (iii) the global PEA spanned the entire AR and was due to global-scale reconnection occurring at heights of about one solar radius, indicating the global spatial and temporal scale of the eruption.« less

  18. Kilauea's double eruption, 2008-2016: volatile budget and associated hazards

    NASA Astrophysics Data System (ADS)

    Sutton, A. J.; Elias, T.

    2016-12-01

    After 20 years of effusive behavior on Kilauea's East Rift Zone, a surge in magma supply brought about eruptive changes that significantly improved our understanding of volcanic processes and associated hazards. The volcano's summit deformation changes and increase in CO2 emissions signaled the supply surge beginning in 2003, and heralded the opening of the Overlook Vent in 2008. Along with the supply surge and vent opening came a dramatic spike in gas release. Summit SO2 emissions climbed from 0.2 kt/d to over 10 kt/d while East Rift discharge rose from 2 kt/d to about 6 kt/d before both summit and rift emissions began an overall decline in late 2008. In spite of the emissions decline, however, overall gas release from Kilauea remained well above the previous 20-year average through early 2014. Beginning in 2008, the annual gas budget released from the summit and rift combined, was more than 830 kt, 6.7 kt, and 3.7 kt of SO2, HCl, and HF, respectively. Effects of these elevated emissions sustained ongoing human health concerns and caused a multi-year agricultural disaster designation for the Island. The current activity of Kīlauea consists of a predominant summit gas eruption (where lava and ash discharge are trivial compared to gas release) and a more typical rift lava eruption with sufficient lava effusion to reach a community 20 km from the eruptive vent. An updated gas-based lava effusion estimate shows that Kilauea continued to erupt an average of 0.11 km^3 yr^-1 of dense rock equivalent lava between early 2012 and mid-2016. This value shows that despite the new regime of erupting most of its gas budget at the volcano's summit, the Kilauea system is still capable of pushing magma out of its rift at a rate consistent with the long term average.

  19. A Study of External Magnetic Reconnection that Triggers a Solar Eruption

    NASA Astrophysics Data System (ADS)

    Zhou, G. P.; Zhang, J.; Wang, J. X.; Wheatland, M. S.

    2017-12-01

    External magnetic reconnection (EMR) is suggested to play an essential role in triggering a solar eruption, but is rarely directly observed. Here, we report on a filament eruption on 2014 October 3 that apparently involves the process of an early EMR. A total of 1.7 × 1020 Mx flux was first canceled along the filament-related polarity inversion line over 12 hr, and then the filament axis started to brighten in extreme ultraviolet (EUV). An impulsive EUV brightening began 30 minutes later, and we attribute this to EMR, as it is located at the center of a bidirectional outflow with a velocity of 60-75 km s-1 along large-scale magnetic loops from active regions NOAA 12178 and 12179, respectively, and over the filament mentioned above. Following the EMR, the filament was activated; then, partial eruption occurred 6 minutes later in the west, in which the decay index above the magnetic flux rope (MFR) reached the critical value of 1.5. The observations are interpreted in terms of underlying magnetic flux cancelation leading to the buildup and eventual formation of the MFR with a filament embedded in it, and the MFR is elevated later. The activated MFR rises and pushes the overlying sheared field and forms a current sheet causing the EMR. The EMR in turn weakens the constraining effect of the overlying field, leading to the arising of the MFR, and subsequently erupting due to torus instability.

  20. Rapid transport of ash and sulfate from the 2011 Puyehue-Córdon Caulle (Chile) eruption to West Antarctica

    NASA Astrophysics Data System (ADS)

    Dowd, E.; Koffman, B. G.; Osterberg, E. C.; Ferris, D. G.; Hartman, L.; Wheatley, S.; Kurbatov, A.; Wong, G. J.; Markle, B. R.; Dunbar, N. W.; Kreutz, K. J.; Yates, M. G.

    2017-12-01

    The VEI 5 eruption of the Puyehue-Cordón Caulle volcanic complex (PCC) in central Chile, which began 4 June 2011, provides a rare opportunity to assess the rapid transport and deposition of sulfate and ash from a mid-latitude volcano to the Antarctic ice sheet. We present sulfate, microparticle concentrations of fine-grained ( 5 μm diameter) tephra, and geochemistry, which document the depositional sequence of volcanic products from the PCC eruption in West Antarctic snow and shallow firn. From the depositional phasing and duration of ash and sulfate peaks, we infer that transport occurred primarily through the troposphere but that ash and sulfate transport were decoupled. We use Hysplit back-trajectory modeling to assess circulation conditions in the weeks following the eruption, and find that atmospheric conditions favored mid-to-high latitude air parcel transport during 6-14 June and 4-18 July, 2011. We suggest that two discrete pulses of cryptotephra deposition relate to these intervals, and as such, constrain the sulfate transport and deposition lifespan to the 2-3 weeks following the eruption. Finally, we compare PCC depositional patterns to those of prominent low- and high-latitude eruptions in order to improve multiparameter-based efforts to identify "unknown source" eruptions in the ice core record. Our observations suggest that mid-latitude eruptions such as PCC can be distinguished from explosive tropical eruptions by differences in ash/sulfate phasing and in the duration of sulfate deposition, and from high-latitude eruptions by differences in particle size distribution and in cryptotephra geochemical composition.

  1. Shallow conduit processes of the 1991 Hekla eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Gudnason, J.; Thordarson, T.; Houghton, B. F.

    2013-12-01

    On January 17, 1991 at 17:00 hrs, the 17th eruption of Hekla since 1104AD began. Lasting for almost two months, it produced 0.02 km3 of icelandite tephra and ~0.15km3 of icelandite lava. This eruption was the third of four eruptions since 1980 with a recurrence period of approximately 10 years, as opposed to a recurrence interval of c. 55 years for the eruptions in the period 1104AD to 1947AD. [1] The last four Hekla eruptions are typified by a 0.5-2 hour-long initial phase of subplinian intensity and discharge ranging from 2900-6700 m3/s [2]. In all 4 events the inital phase was followed by a sustained and relatively low-discharge(<20 m3/s) effusive phase, which in the case of Hekla 1991 lasted until the 11th March 1991 [1]. The initial phase of the 1991 event lasted for ~50 minutes and sustained an eruption plume that rose to 11.5 km in about 10 minutes [1]. The plume was dispersed to the NNE at velocities of 60-70 km/hr producing a well-sorted tephra fall covering >20,000 km2. Here we examine the first phase of the Hekla 1991 eruption with focus on vesiculation and fragmentation processes in the shallow conduit and ash production. Samples of the tephra fall were collected on snow immediately after the initial phase at multiple sites providing a representative spatial coverage within the 0.1mm isopach [3]. This set was augmented by samples collected in 2012 to provide tighter coverage of near vent region. Grain size of all samples has been measured down to 1 micron. Density measurements have been conducted on 4 near-vent pumice samples (100 clasts each) and the pumice vesicle size distribution has been determined in a selected subset of clasts. The reconstructed whole deposit grain size distribution exhibits a unimodal, log-normal distribution peaking at -3 phi, typical of dry, magmatic fragmentation. Pumice densities range from 520-880 kg/m3 and exhibit a tight unimodal and log-normal distribution indicating a mean vesicularity of 77% to 79% for the magma

  2. Kilauea's Ongoing Eruption: 25th Year Brings Major Changes

    NASA Astrophysics Data System (ADS)

    Orr, T. R.

    2007-12-01

    2007 marks the 25th year of nearly continuous eruption on Kilauea's east rift zone. Episodic high lava fountains, which built the Pu`u `O`o cone during the first three years of the eruption, ended in 1986. Activity then migrated downrift and the Kupaianaha shield was formed by passive effusion of lava. The change in eruptive style resulted in a switch at Pu`u `O`o from cone construction to cone collapse that has been ongoing for the last two decades. Activity at Kupaianaha ceased in 1992, and the eruption resumed at Pu`u `O`o. The eruptive style established at Kupaianaha continued, however, with continuous effusion from vents on the southwest flank of the Pu`u `O`o cone. The last 15 years have been characterized by the formation of relatively stable tube systems---broken only by a brief fissure eruption uprift of Pu`u `O`o in 1997---that have carried lava from the flank vents to the ocean about 9 km away. The Prince Kuhio Kalanianaole (PKK) tube, the most recent of these tube systems to develop, was active from March 2004 to June 2007. The PKK flow was emplaced almost entirely on older flows of this eruption and entered the ocean in several locations over a span of 6 km. The "Father's Day" intrusion of June 17--19, 2007, robbed the supply of magma to Pu`u `O`o and, thus, the active flow field. The floor of the Pu`u `O`o crater dropped 80--100 m, the PKK tube system drained, and the active flows and ocean entry quickly stagnated. On June 19, a short-lived fissure eruption broke out low on the east flank of Kane Nui o Hamo, about 6 km uprift of Pu`u `O`o, burying only 0.22 hectares. The eruption at Kilauea paused from June 20 through July 1 or 2, when lava returned to Pu`u `O`o and began refilling the collapsed crater. Near midnight on July 20--21, after at least 19 days of lava lake growth, the lava pond within the Pu`u `O`o crater drained suddenly when a series of fissures opened on the east flank of the cone and propagated ~2 km downrift. The new activity, dubbed

  3. The Lusi eruption and implications for understanding fossil piercement structures in sedimentary basins

    NASA Astrophysics Data System (ADS)

    Svensen, Henrik; Mazzini, Adriano; Planke, Sverre; Hadi, Soffian

    2016-04-01

    The Lusi eruption started in northeast Java, Indonesia, on May 29th 2006, and it has been erupting rocks, mud, water, and gas ever since. We have been doing field work and research on Lusi ever since the eruption commenced. This work was initially motivated from studying the initiation of a mud volcano. However, the longevity of the eruption has made it possible to describe and monitor the lifespan of this unique piercement structure. . One of the first-order questions regarding the eruption is how it should be classified and if there are any other modern or fossil analogues that can place Lusi in a relevant geological context. During the initial stages of eruption, Lusi was classified as a mud volcano, but following geochemical studies the eruption did not show the typical CH4-dominated gas composition of other mud volcanoes and the temperature was also too high. Moreover, mud volcano eruptions normally last a few days, but Lusi never stopped during the past decade. In particular, the crater fluid geochemistry suggests a connection to the neighboring volcanic complex. Lusi represent a sedimentary hosted hydrothermal system. This opens up new possibilities for understanding fossil hydrothermal systems in sedimentary basins, such as hydrothermal vent complexes and breccia-pipes found in sedimentary basins affected by the formation of Large igneous provinces. We will present examples from the Karoo Basin (South Africa) and the Vøring Basin (offshore Norway) and discuss how Lusi can be used to refine existing formation models. Finally, by comparing Lusi to fossil hydrothermal systems we may get insight into the processes operating at depth where the Lusi system interacts with the igneous rocks of the neighbouring volcanic arc.

  4. Temporal changes in stress preceding the 2004-2008 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Lehto, H.L.; Roman, D.C.; Moran, S.C.

    2010-01-01

    The 2004-2008 eruption of Mount St. Helens (MSH), Washington, was preceded by a swarm of shallow volcano-tectonic earthquakes (VTs) that began on September 23, 2004. We calculated locations and fault-plane solutions (FPS) for shallow VTs recorded during a background period (January 1999 to July 2004) and during the early vent-clearing phase (September 23 to 29, 2004) of the 2004-2008 eruption. FPS show normal and strike-slip faulting during the background period and on September 23; strike-slip and reverse faulting on September 24; and a mixture of strike-slip, reverse, and normal faulting on September 25-29. The orientation of ??1 beneath MSH, as estimated from stress tensor inversions, was found to be sub-horizontal for all periods and oriented NE-SW during the background period, NW-SE on September 24, and NE-SW on September 25-29. We suggest that the ephemeral ~90?? change in ??1 orientation was due to intrusion and inflation of a NE-SW-oriented dike in the shallow crust prior to the eruption onset. ?? 2010 Elsevier B.V.

  5. Assessing eruption column height in ancient flood basalt eruptions

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    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 ∼ 45 ° N. Assuming 5 km long active fissure segments and 9000 Mt of SO2 released during explosive phases over a 10-15 year duration, the ∼ 180km of known Roza fissure length could have supported ∼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 (∼ 66Ma) 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 flood basalt eruptions could have influenced

  6. 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

  7. Incorporating the eruptive history in a stochastic model for volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Bebbington, Mark

    2008-08-01

    We show how a stochastic version of a general load-and-discharge model for volcanic eruptions can be implemented. The model tracks the history of the volcano through a quantity proportional to stored magma volume. Thus large eruptions can influence the activity rate for a considerable time following, rather than only the next repose as in the time-predictable model. The model can be fitted to data using point-process methods. Applied to flank eruptions of Mount Etna, it exhibits possible long-term quasi-cyclic behavior, and to Mauna Loa, a long-term decrease in activity. An extension to multiple interacting sources is outlined, which may be different eruption styles or locations, or different volcanoes. This can be used to identify an 'average interaction' between the sources. We find significant evidence that summit eruptions of Mount Etna are dependent on preceding flank eruptions, with both flank and summit eruptions being triggered by the other type. Fitted to Mauna Loa and Kilauea, the model had a marginally significant relationship between eruptions of Mauna Loa and Kilauea, consistent with the invasion of the latter's plumbing system by magma from the former.

  8. Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history

    NASA Astrophysics Data System (ADS)

    Thordarson, T.; Larsen, G.

    2007-01-01

    The large-scale volcanic lineaments in Iceland are an axial zone, which is delineated by the Reykjanes, West and North Volcanic Zones (RVZ, WVZ, NVZ) and the East Volcanic Zone (EVZ), which is growing in length by propagation to the southwest through pre-existing crust. These zones are connected across central Iceland by the Mid-Iceland Belt (MIB). Other volcanically active areas are the two intraplate belts of Öræfajökull (ÖVB) and Snæfellsnes (SVB). The principal structure of the volcanic zones are the 30 volcanic systems, where 12 are comprised of a fissure swarm and a central volcano, 7 of a central volcano, 9 of a fissure swarm and a central domain, and 2 are typified by a central domain alone. Volcanism in Iceland is unusually diverse for an oceanic island because of special geological and climatological circumstances. It features nearly all volcano types and eruption styles known on Earth. The first order grouping of volcanoes is in accordance with recurrence of eruptions on the same vent system and is divided into central volcanoes (polygenetic) and basalt volcanoes (monogenetic). The basalt volcanoes are categorized further in accordance with vent geometry (circular or linear), type of vent accumulation, characteristic style of eruption and volcanic environment (i.e. subaerial, subglacial, submarine). Eruptions are broadly grouped into effusive eruptions where >95% of the erupted magma is lava, explosive eruptions if >95% of the erupted magma is tephra (volume calculated as dense rock equivalent, DRE), and mixed eruptions if the ratio of lava to tephra occupy the range in between these two end-members. Although basaltic volcanism dominates, the activity in historical time (i.e. last 11 centuries) features expulsion of basalt, andesite, dacite and rhyolite magmas that have produced effusive eruptions of Hawaiian and flood lava magnitudes, mixed eruptions featuring phases of Strombolian to Plinian intensities, and explosive phreatomagmatic and magmatic

  9. The Largest Holocene Eruption of the Central Andes Found

    NASA Astrophysics Data System (ADS)

    Fernandez-Turiel, J.; Rodriguez-Gonzalez, A.; Saavedra, J.; Perez-Torrado, F.; Carracedo, J.; Osterrieth, M.; Carrizo, J.; Esteban, G.

    2013-12-01

    We present new data and interpretation about a major eruption -spreading ˜110 km3 ashes over 440.000 km2- long thought to have occurred around 4200 years ago in the Cerro Blanco Volcanic Complex (CBVC) in NW Argentina. This eruption may be the biggest during the past five millennia in the Central Volcanic Zone of the Andes, and possibly one of the largest Holocene eruptions in the world. The environmental effects of this voluminous eruption are still noticeable, as evidenced by the high content of arsenic and other trace elements in the groundwaters of the Chacopampean Plain. The recognition of this significant volcanic event may shed new light on interpretations of critical changes observed in the mid-Holocene paleontological and archaeological records, and offers researchers an excellent, extensive regional chronostratigraphic marker for reconstructing mid-Holocene geological history over a wide geographical area of South America. More than 100 ashes were sampled in Argentina, Chile and Uruguay during different field campaigns. Ash samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), grain size distributions laser diffraction, and geochemically by electron microprobe (EMPA) and laser ablation-HR-ICP-MS. New and published 14C ages were calibrated to calendar years BP. The age of the most recent CBVC eruption is 4407-4093 cal y BP, indirectly dated by 14C of associated organic sediment within the lower part of a proximal fall deposit of this event (26°53'16.05"S-67°44'48.68"W). This is the youngest record of a major volcanic event in the Southern Puna. This age is consistent with other radiocarbon dates of organic matter in palaeosols underlying or overlying distal ash fall deposits. Based on their products, all of rhyolitic composition, we have distinguished 8 main episodes during the evolution of the most recent CBVC eruption: 1) the eruption began with a white rhyolite lava dome extrusion; 2) followed by a Plinian

  10. Rapid transport of ash and sulfate from the 2011 Puyehue-Cordón Caulle (Chile) eruption to West Antarctica

    NASA Astrophysics Data System (ADS)

    Koffman, Bess G.; Dowd, Eleanor G.; Osterberg, Erich C.; Ferris, David G.; Hartman, Laura H.; Wheatley, Sarah D.; Kurbatov, Andrei V.; Wong, Gifford J.; Markle, Bradley R.; Dunbar, Nelia W.; Kreutz, Karl J.; Yates, Martin

    2017-08-01

    The Volcanic Explosivity Index 5 eruption of the Puyehue-Cordón Caulle volcanic complex (PCC) in central Chile, which began 4 June 2011, provides a rare opportunity to assess the rapid transport and deposition of sulfate and ash from a midlatitude volcano to the Antarctic ice sheet. We present sulfate, microparticle concentrations of fine-grained ( 5 μm diameter) tephra, and major oxide geochemistry, which document the depositional sequence of volcanic products from the PCC eruption in West Antarctic snow and shallow firn. From the depositional phasing and duration of ash and sulfate peaks, we infer that transport occurred primarily through the troposphere but that ash and sulfate transport were decoupled. We use Hybrid Single-Particle Lagrangian Integrated Trajectory back trajectory modeling to assess atmospheric circulation conditions in the weeks following the eruption and find that conditions favored southward air parcel transport during 6-14 June and 4-18 July 2011. We suggest that two discrete pulses of cryptotephra deposition relate to these intervals, and as such, constrain the sulfate transport and deposition lifespan to the 2-3 weeks following the eruption. Finally, we compare PCC depositional patterns to those of prominent low- and high-latitude eruptions in order to improve multiparameter-based efforts to identify "unknown source" eruptions in the ice core record. Our observations suggest that midlatitude eruptions such as PCC can be distinguished from explosive tropical eruptions by differences in ash/sulfate phasing and in the duration of sulfate deposition, and from high-latitude eruptions by differences in particle size distribution and in cryptotephra geochemical composition.

  11. Satellite Observations of Volcanic Clouds from the Eruption of Redoubt Volcano, Alaska, 2009

    NASA Astrophysics Data System (ADS)

    Dean, K. G.; Ekstrand, A. L.; Webley, P.; Dehn, J.

    2009-12-01

    Redoubt Volcano began erupting on 23 March 2009 (UTC) and consisted of 19 events over a 14 day period. The volcano is located on the Alaska Peninsula, 175 km southwest of Anchorage, Alaska. The previous eruption was in 1989/1990 and seriously disrupted air traffic in the region, including the near catastrophic engine failure of a passenger airliner. Plumes and ash clouds from the recent eruption were observed on a variety of satellite data (AVHRR, MODIS and GOES). The eruption produced volcanic clouds up to 19 km which are some of the highest detected in recent times in the North Pacific region. The ash clouds primarily drifted north and east of the volcano, had a weak ash signal in the split window data and resulted in light ash falls in the Cook Inlet basin and northward into Alaska’s Interior. Volcanic cloud heights were measured using ground-based radar, and plume temperature and wind shear methods but each of the techniques resulted in significant variations in the estimates. Even though radar showed the greatest heights, satellite data and wind shears suggest that the largest concentrations of ash may be at lower altitudes in some cases. Sulfur dioxide clouds were also observed on satellite data (OMI, AIRS and Calipso) and they primarily drifted to the east and were detected at several locations across North America, thousands of kilometers from the volcano. Here, we show time series data collected by the Alaska Volcano Observatory, illustrating the different eruptive events and ash clouds that developed over the subsequent days.

  12. Evidence for Gradual External Reconnection Before Explosive Eruption of a Solar Filament

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2004-01-01

    evolution is consistent with gradual breakout that led to (and perhaps caused) the fast eruption. Tether-cutting reconnection below the filament begins early in the rapid ejection. but our data are not complete enough to determine whether this reconnection began early enough to be the cause of the fast-phase onset. Thus, our observations are consistent with gradual breakout reconnection causing the long slow rise of the filament, but allow the cause of the sudden onset of the explosive fast phase to be either a jump in the breakout reconnection rate or the onset of runaway tether-cutting reconnection. or both.

  13. Evidence for Gradual External Reconnection Before Explosive Eruption of a Solar Filament

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2003-01-01

    . The pre-eruption evolution is consistent with gradual breakout that led to (and perhaps caused) the fast eruption. Tether-cutting reconnection below the filament begins early in the rapid ejection, but our data are not complete enough to determine whether this reconnection began early enough to be the cause of the fast-phase onset. Thus, our observations are consistent with gradual breakout reconnection causing the long slow rise of the filament, but allow the cause of the sudden onset of the explosive fast phase to be either a jump in the breakout reconnection rate or the onset of runaway tether-cutting reconnection, or both.

  14. The 1999 eruption of Shishaldin Volcano, Alaska: Monitoring a distant eruption

    USGS Publications Warehouse

    Nye, C.J.; Keith, T.E.C.; Eichelberger, J.C.; Miller, T.P.; McNutt, S.R.; Moran, S.; Schneider, D.J.; Dehn, J.; Schaefer, J.R.

    2002-01-01

    Shishaldin Volcano, in the central Aleutian volcanic arc, became seismically restless during the summer of 1998. Increasing unrest was monitored using a newly installed seismic network, weather satellites, and rare local visual observations. The unrest culminated in large eruptions on 19 April and 22-23 April 1999. The opening phase of the 19 April eruption produced a sub-Plinian column that rose to 16 km before rapidly dissipating. About 80 min into the 19 April event we infer that the eruption style transitioned to vigorous Strombolian fountaining. Exceptionally vigorous seismic tremor heralded the 23 April eruption, which produced a large thermal anomaly observable by satellite, but only a modest, 6-km-high plume. There are no ground-based visual observations of this eruption; however we infer that there was renewed, vigorous Strombolian fountaining. Smaller low-level ash-rich plumes were produced through the end of May 1999. The lava that erupted was evolved basalt with about 49% SiO2. Subsequent field investigations have been unable to find a distinction between deposits from each of the two major eruptive episodes.

  15. The A.D. 79 eruption as a future explosive scenario in the Vesuvian area: evaluation of associated risk

    NASA Astrophysics Data System (ADS)

    Lirer, Lucio; Munno, Rosalba; Postiglione, Immacolata; Vinci, Anna; Vitelli, Livia

    Due to the lack of an effective policy of planning and prevention, over the past decades the area around Mt. Vesuvio has undergone a steady increase in population and uncontrolled housing development. Consequently, it has become one of the most hazardous volcanic areas in the world. In order to mitigate the damage that the impact of an explosive event would cause in the area, the Department of Civil Defense has worked out an Emergency Management Plan using the A.D. 1631 subplinian eruption as the most probable short-term event. However, from 25 000 years B.P. to present, the activity of the Somma-Vesuvio volcano has shown a sequence of eight eruptive cycles, which always began with a strong plinian eruption. In this paper we utilize the A.D. 79 eruption as an example of a potential large explosive eruption that might occur again at Vesuvio. A detailed tephrostratigraphic analysis of the eruption products was processed by a multivariate statistical analysis. This analysis proved useful for identifying marker layers in the sequences, thus allowing the recognition of some major phases of synchronous deposition and hence the definition of the chronological and spatial evolution of the eruption. By combining this reconstruction with land-use maps, a scenario is proposed with time intervals in the eruptive sequence similar to those reported in Pliny's letter. Thus, it was calculated that, after 7h from the start of the eruption, a total area of approximately 300km2 would be covered with the eruption products. In the following 11h, a total area of approximately 500km2 would be involved. The third and last phase of deposition would not cause significant variation in the total area involved, but it would bring about an increase in the thickness of the pyroclastic deposits in the perivolcanic area.

  16. Textural and geochemical constraints on eruptive style of the 79AD eruption at Vesuvius

    NASA Astrophysics Data System (ADS)

    Balcone-Boissard, Hélène; Boudon, Georges; Villemant, Benoît.

    2010-05-01

    The 79AD eruption of Vesuvius, also known as the "Pompeii eruption", is the reference for one of the explosive eruptive styles, the plinian-type eruption. The eruption involved H2O-rich phonolitic magmas and is commonly divided into three phases: an initial phreatomagmatic phase, followed by a plinian event which produced a thick pumice fallout deposit and a final phase that was dominated by numerous column-collapse events. During the plinian phase, a first white pumice fallout was produced from a high steady eruptive column, followed by a grey pumice fallout originated by an oscillatory eruptive column with several partial column collapse events. This study focuses on the pumice fallout deposits, sampled in a proximal thick section, at the Terzigno quarry, 6 km southeast of the present crater. In order to constrain the degassing processes and the eruptive dynamics, major element compositions, residual volatile contents (H2O, Cl) and textural characteristics (vesicularity and microcrystallinity) were studied. A previous study that we performed on the pre-eruptive Cl content has shown that Cl may be used as an indicator of magma saturation with Cl-rich fluids and of pre-eruptive pressures. Cl contents measured in melt inclusions show that only the white pumice and the upper part of the grey pumice magma were H2O saturated prior eruption. Large variations in residual volatile contents exist between the different eruptive units and textural features strongly differ between white and grey pumice clasts but also within the grey pumice clasts. The degassing processes were thus highly heterogeneous: the white pumice eruptive units represent a typical closed-system degassing evolution whereas the first grey pumice one, stored in the same pre-eruptive saturation conditions, follows a particular open-system degassing evolution. Here we propose a new model of the 79AD eruption where pre-eruptive conditions (H2O saturation, magma temperature and viscosity) are the critical

  17. The Eruption Forecasting Information System: Volcanic Eruption Forecasting Using Databases

    NASA Astrophysics Data System (ADS)

    Ogburn, S. E.; Harpel, C. J.; Pesicek, J. D.; Wellik, J.

    2016-12-01

    Forecasting eruptions, including the onset size, duration, location, and impacts, is vital for hazard assessment and risk mitigation. The Eruption Forecasting Information System (EFIS) project is a new initiative of the US Geological Survey-USAID Volcano Disaster Assistance Program (VDAP) and will advance VDAP's ability to forecast the outcome of volcanic unrest. The project supports probability estimation for eruption forecasting by creating databases useful for pattern recognition, identifying monitoring data thresholds beyond which eruptive probabilities increase, and for answering common forecasting questions. A major component of the project is a global 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. This module allows us to query eruption chronologies, monitoring data, descriptive information, operational data, and eruptive phases alongside other global databases, such as WOVOdat and the Global Volcanism Program. The EFIS database is in the early stages of development and population; thus, this contribution also is a request for feedback from the community. Preliminary data are already benefitting several research areas. For example, VDAP provided a forecast of the likely remaining eruption duration for Sinabung volcano, Indonesia, using global data taken from similar volcanoes in the DomeHaz database module, in combination with local monitoring time-series data. In addition, EFIS seismologists used a beta-statistic test and empirically-derived thresholds to identify distal volcano-tectonic earthquake anomalies preceding Alaska volcanic eruptions during 1990-2015 to retrospectively evaluate Alaska Volcano Observatory eruption precursors. This has identified important considerations for selecting analog volcanoes for global data analysis, such as differences between

  18. Eruptive History and Chemical Evolution of the Precaldera and Postcaldera Basalt-Dacite Sequences, Long Valley, California: Implications for Magma Sources, Current Seismic Unrest, and Future Volcanism

    USGS Publications Warehouse

    Bailey, Roy A.

    2004-01-01

    The Long Valley Volcanic Field in east-central California straddles the East Sierran frontal fault zone, overlapping the Sierra Nevada and western Basin and Range Provinces. The volcanic field overlies a mature mid-Tertiary erosional surface that truncates a basement composed mainly of Mesozoic plutons and associated roof pendants of Mesozoic metavolcanic and Paleozoic metasedimentary rocks. Long Valley volcanism began about 4 Ma during Pliocene time and has continued intermittently through the Holocene. The volcanism is separable into two basalt-rhyolite episodes: (1) an earlier, precaldera episode related to Long Valley Caldera that climaxed with eruption of the Bishop Tuff and collapse of the caldera; and (2) a later, postcaldera episode structurally related to the north-south-trending Mono-Inyo Craters fissure system, which extends from the vicinity of Mammoth Mountain northward through the west moat of the caldera to Mono Lake. Eruption of the basalt-dacite sequence of the precaldera basalt-rhyolite episode peaked volumetrically between 3.8 and 2.5 Ma; few basalts were erupted during the following 1.8 m.y. (2.5?0.7 Ma). Volcanism during this interval was dominated by eruption of the voluminous rhyolites of Glass Mountain (2.2?0.8 Ma) and formation of the Bishop Tuff magma chamber. Catastrophic rupture of the roof of this magma chamber caused eruption of the Bishop Tuff and collapse of Long Valley Caldera (760 ka), after which rhyolite eruptions resumed on the subsided caldera floor. The earliest postcaldera rhyolite flows (700?500 ka) contain quenched globular basalt enclaves (mafic magmatic inclusions), indicating that basaltic magma had reentered shallow parts of the magmatic system after a 1.8-m.y. hiatus. Later, at about 400 ka, copious basalts, as well as dacites, began erupting from vents mainly in the west moat of the caldera. These later eruptions initiated the postcaldera basalt-rhyolite episode related to the Mono-Inyo Craters fissure system, which

  19. Cyclic Explosivity in High Elevation Phreatomagmatic Eruptions at Ocean Island Volcanoes: Implications for Aquifer Pressurization and Volcano Flank Destabilization.

    NASA Astrophysics Data System (ADS)

    Tarff, R.; Day, S. J.; Downes, H.; Seghedi, I.

    2015-12-01

    Groundwater heating and pressurization of aquifers trapped between dikes in ocean island volcanoes has been proposed as a mechanism for destabilizing and triggering large-volume flank collapses. Previous modelling has indicated that heat transfer from sustained magma flow through dikes during eruption has the potential to produce destabilizing levels of pressure on time scales of 4 to 400 days, if the aquifers remain confined. Here we revisit this proposal from a different perspective. We examine evidence for pressure variations in dike-confined aquifers during eruptions at high elevation vents on ocean island volcanoes. Initially magmatic, these eruptions change to mostly small-volume explosive phreatomagmatic activity. A recent example is the 1949 eruption on La Palma, Canary Islands. Some such eruptions involve sequences of larger-volume explosive phases or cycles, including production of voluminous low-temperature, pyroclastic density currents (PDC). Here we present and interpret data from the Cova de Paul crater eruption (Santo Antao, Cape Verde Islands). The phreatomagmatic part of this eruption formed two cycles, each culminating with eruption of PDCs. Compositional and textural variations in the products of both cycles indicate that the diatreme fill began as coarse-grained and permeable which allowed gas to escape. During the eruption, the fill evolved to a finer grained, poorly sorted, less permeable material, in which pore fluid pressures built up to produce violent explosive phases. This implies that aquifers adjacent to the feeder intrusion were not simply depressurized at the onset of phreatomagmatic explosivity but experienced fluctuations in pressure throughout the eruption as the vent repeatedly choked and emptied. In combination with fluctuations in magma supply rate, driving of aquifer pressurization by cyclical vent choking will further complicate the prediction of flank destabilization during comparable eruptions on ocean island volcanoes.

  20. Holocene eruption history in Iceland - Eruption frequency vs. Tephra layer frequency

    NASA Astrophysics Data System (ADS)

    Oladottir, B. A.; Larsen, G.

    2012-12-01

    Volcanic deposits of all kinds are used to reconstruct eruption history of volcanoes and volcanic zones. In Iceland tephra is the ideal volcanic deposit to study eruption history as two out of every three eruptions taking place there during the last 11 centuries have been explosive, leaving tephra as their only product. If eruptions producing both lava and tephra are included three out of every four eruptions have produced tephra. Tephra dispersal and deposition depends on factors such as eruption magnitude, eruption cloud height, duration of eruption and prevailing wind directions at the time of eruption. Several outcrops around a particular volcano must therefore be measured to obtain optimal information of its eruption history. Vegetation in the area of deposition is also of great importance for its preservation. Tephra deposited on un-vegetated land is rapidly eroded by wind and water, and deposits up to few tens of cm thickness may be lost from the record. Such tephra deposited on grassy or forested land is at least partly sheltered from the wind after deposition. Soon after tephra deposition (how soon depends on tephra thickness) the root system of the vegetation creates an even better shelter for the tephra and when this stage is reached the tephra is preserved in the soil for millennia, given that no soil erosion takes place. Vegetation is often boosted in the first years after tephra deposition which in turn helps tephra preservation. A setback of using soil sections for reconstructing Holocene eruption history is the lack of soil at the beginning of the era but for that time period tephra records in lake and marine sediments can be used. When tephra stratigraphy in soil sections is measured to study eruption history and eruption frequency of a volcano it must be kept in mind that what is seen is in fact the tephra layer frequency. One section only shows tephra layers deposited in that location and more importantly only the layers preserved there. The

  1. Use of digital aerophotogrammetry to determine rates of lava dome growth, Mount St. Helens, Washington, 2004-2005: Chapter 8 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Schilling, Steve P.; Thompson, Ren A.; Messerich, James A.; Iwatsubo, Eugene Y.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Successful application of aerophotogrammetry was possible during the critical earliest parts of the eruption because we had baseline data and photogrammetric infrastructure in place before the eruption began. The vertical aerial photographs, including the DEMs and calculations derived from them, were one of the most widely used data sets collected during the 2004-5 eruption, as evidenced in numerous contributions to this volume. These data were used to construct photogeologic maps, deformation vector fields, and profiles of the evolving dome and glacier. Extruded volumes and rates proved to be critical parameters to constrain models and hypotheses of eruption dynamics and thus helped to assess volcano hazards.

  2. Kilauea's 5-9 March 2011 Kamoamoa fissure eruption and its relation to 30+ years of activity from Pu'u 'Ō'ō: Chapter 18

    USGS Publications Warehouse

    Orr, Tim R.; Poland, Michael P.; Patrick, Matthew R.; Thelen, Weston A.; Sutton, A.J.; Elias, Tamar; Thornber, Carl R.; Parcheta, Carolyn; Wooten, Kelly M.; Carey, Rebecca; Cayol, Valérie; Poland, Michael P.; Weis, Dominique

    2015-01-01

    Lava output from Kīlauea's long-lived East Rift Zone eruption, ongoing since 1983, began waning in 2010 and was coupled with uplift, increased seismicity, and rising lava levels at the volcano's summit and Pu‘u ‘Ō‘ō vent. These changes culminated in the four-day-long Kamoamoa fissure eruption on the East Rift Zone starting on 5 March 2011. About 2.7 × 106 m3 of lava erupted, accompanied by ˜15 cm of summit subsidence, draining of Kīlauea's summit lava lake, a 113 m drop of Pu‘u ‘Ō‘ō's crater floor, ˜3 m of East Rift Zone widening, and eruptive SO2 emissions averaging 8500 tonnes/day. Lava effusion resumed at Pu‘u ‘Ō‘ō shortly after the Kamoamoa eruption ended, marking the onset of a new period of East Rift Zone activity. Multiparameter monitoring before and during the Kamoamoa eruption suggests that it was driven by an imbalance between magma supplied to and erupted from Kīlauea's East Rift Zone and that eruptive output is affected by changes in the geometry of the rift zone plumbing system. These results imply that intrusions and eruptive changes during ongoing activity at Kīlauea may be anticipated from the geophysical, geological, and geochemical manifestations of magma supply and magma plumbing system geometry.

  3. Introduction to Augustine Volcano and Overview of the 2006 Eruption

    NASA Astrophysics Data System (ADS)

    Nye, C. J.

    2006-12-01

    This overview represents the combined efforts of scores of people, including Alaska Volcano Observatory staff from the US Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys; additional members of those agencies outside of AVO; and volcanologists from elsewhere. Augustine is a young, and therefore small island volcano in the Cook Inlet region of the eastern Aleutian arc. It is among the most active volcanoes in the arc, with six major historic eruptions, and a vigorous eruptive history going back at least 2,500 years. Eruptions typically begin explosively, and finish with the extrusion of domes and sometimes short, steep lava flows. At least 14 times (most recently in 1883) the -summit has become over-steepened and failed, producing debris avalanches which reached tidewater. Magmas within each of the well-studied eruptions are crystal-rich andesite spanning up to seven weight percent silica. Mixing and mingling are ubiquitous and occur at scales from meters to microns. In general, magmagenesis at Augustine is open, messy, and transcrustal. The 2006 eruption was broadly similar to the 20th century eruptions. Unrest began midway through 2005, with steadily increasing numbers of microearthquakes and continuous inflation of the edifice. By mid-December there were obvious morphological and thermal changes at the summit, as well as phreatic explosions and more passive venting of S-rich gasses. In mid-January 2006 phreatomagmatic explosions gave way to magmatic explosions, producing pyroclastic flows dominated by low-silica andesite, as well as lahars, followed by a small summit dome. In late January the nature of seismicity, eruptive style, and type of erupted magma all changed, and block-and-ash flows of high-silica, crystal-rich andesite were emplaced as the edifice deflated. Re-inflation well below the edifice and low-level effusion continued through February. During the second week

  4. Large, Moderate or Small? The Challenge of Measuring Mass Eruption Rates in Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Dürig, T.; Hognadottir, T.; Hoskuldsson, A.; Bjornsson, H.; Barsotti, S.; Petersen, G. N.; Thordarson, T.; Pedersen, G. B.; Riishuus, M. S.

    2015-12-01

    The potential impact of a volcanic eruption is highly dependent on its eruption rate. In explosive eruptions ash may pose an aviation hazard that can extend several thousand kilometers away from the volcano. Models of ash dispersion depend on estimates of the volcanic source, but such estimates are prone to high error margins. Recent explosive eruptions, including the 2010 eruption of Eyjafjallajökull in Iceland, have provided a wealth of data that can help in narrowing these error margins. Within the EU-funded FUTUREVOLC project, a multi-parameter system is currently under development, based on an array of ground and satellite-based sensors and models to estimate mass eruption rates in explosive eruptions in near-real time. Effusive eruptions are usually considered less of a hazard as lava flows travel slower than eruption clouds and affect smaller areas. However, major effusive eruptions can release large amounts of SO2 into the atmosphere, causing regional pollution. In very large effusive eruptions, hemispheric cooling and continent-scale pollution can occur, as happened in the Laki eruption in 1783 AD. The Bárdarbunga-Holuhraun eruption in 2014-15 was the largest effusive event in Iceland since Laki and at times caused high concentrations of SO2. As a result civil protection authorities had to issue warnings to the public. Harmful gas concentrations repeatedly persisted for many hours at a time in towns and villages at distances out to 100-150 km from the vents. As gas fluxes scale with lava fluxes, monitoring of eruption rates is therefore of major importance to constrain not only lava but also volcanic gas emissions. This requires repeated measurements of lava area and thickness. However, most mapping methods are problematic once lava flows become very large. Satellite data on thermal emissions from eruptions have been used with success to estimate eruption rate. SAR satellite data holds potential in delivering lava volume and eruption rate estimates

  5. Breaking the Habit - The peculiar 2016 eruption of the remarkable recurrent nova M31N 2008-12a

    NASA Astrophysics Data System (ADS)

    Henze, Martin; M31N 2008-12a Monitoring Collaboration

    2018-01-01

    Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every year. This makes it the most extreme member of the new class of Rapidly Recurring Novae (RRN) which show repeated eruptions within a time span of a decade or less. Such frequent outbursts indicate a high mass accretion rate onto a white dwarf that is extremely close to the Chandrasekhar limit, thereby making RRN the most promising observable candidates for the progenitors of type-Ia supernovae currently known.The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multi-wavelength properties. From a relatively faint peak brightness the optical light curve declined rapidly by two magnitudes in less than two days. Early spectra showed high velocities that declined significantly within days and displayed clear helium and nitrogen lines throughout. The supersoft X-ray source phase of the nova began extremely early, around day six after eruption, and only lasted for about two weeks.In contrast, the delayed 2016 eruption showed significant deviations from the established pattern. In this talk, I will discuss the observational results and their impact on our understanding of the physics and evolution of this unique nova.

  6. Magma degassing and eruption dynamics of the Avellino pumice Plinian eruption of Somma-Vesuvius (Italy). Comparison with the Pompeii eruption

    NASA Astrophysics Data System (ADS)

    Balcone-Boissard, H.; Boudon, G.; Ucciani, G.; Villemant, B.; Cioni, R.; Civetta, L.; Orsi, G.

    2012-05-01

    The eruptive history of Mt. Somma-Vesuvius is characterised by large explosive events: Pomici di Base eruption (22,030 ± 175 yr cal BP), Mercato (8890 ± 90 yr cal BP), Avellino (3945 ± 10 yr cal BP) and Pompeii (79 AD). Pre-eruptive conditions and sin-eruptive degassing processes of the Avellino eruption, the highest-magnitude Plinian event, have been investigated, using volatile contents (F, Cl, H2O) in melt inclusions and residual glass, and textural characteristics of pumice clasts of the 9 fallout layers sampled in detail in a representative sequence. The sequence displays an up-section sharp colour change from white to grey, corresponding to variations in both magma composition and textural characteristics. The pre-eruptive conditions have been constrained by systematic measurements of Cl content in both melt inclusions and matrix glass of pumice clasts. The pumice glass composition varies from Na-rich phonolite (white pumice) to K-rich phonolite (grey pumice). The measured Cl values constantly cluster at 5200 ± 400 ppm (buffer value), whatever the composition of the melt, suggesting that the entire magma body was saturated with sub-critical fluids. This Cl saturation constrains the pre-eruptive pressures and maximum H2O contents at 200 ± 10 MPa and 6.3 ± 0.2 wt.% H2O for the white pumice melt and 195 ± 15 MPa and 5.2 ± 0.2 wt.% H2O for the grey pumice melt. The fluid phase, mainly composed of a H2O-rich vapour phase and brine, probably accumulated at the top of the reservoir and generated an overpressure able to trigger the onset of the eruption. Magma degassing was rather homogeneous for the white and grey eruptive units, mostly occurring through closed-system processes, leading to a typical Plinian eruptive style. A steady-state withdrawal of an H2O-saturated magma may explain the establishment of a sustained Plinian column. Variation from white to grey pumice is accompanied by decrease of mean vesicularity and increase of mean microcrystallinity

  7. Eruption Dynamics and Flow Morphology during the 2005 Sierra Negra Eruption, Galapagos Islands

    NASA Astrophysics Data System (ADS)

    Rader, E.; Harpp, K.; Geist, D.

    2006-12-01

    Sierra Negra volcano began erupting on October 22nd, 2005. The eruption lasted nine days and provided an opportunity to examine emplacement of lava flows and their morphology. During the first two days, fire fountaining produced a broad, unchannelized flow that coated the northern caldera wall and benches directly below the vents as it moved onto the eastern caldera floor. After the first day of the eruption, the caldera floor a'a flow grew primarily by inflation, lateral spreading along linear upwelling regions, and pahoehoe breakouts at the perimeter. Simultaneously, four 4km long rootless flows formed on the northern flanks of the volcano, supplied by spatter from the vents inboard of the caldera rim. Samples from different morphological types of lava from the caldera floor, bench, and outer flanks were collected and examined by BSE imaging. Transitions from pahoehoe to a'a and back to pahoehoe were observed in a low viscosity flow on the caldera bench that cascaded over a steep escarpment. Plagioclase microlite content in the bench flow varies little, with 27% in pahoehoe and 33% in a'a, on average. Consequently, we propose that the transformation was driven by changes in strain rate rather than cooling. As the lava first flowed over the bench edge, the increased strain rate caused it to become a'a. The elevation drop was small enough, however, that the flow remained sufficiently hot to revert to pahoehoe as it pooled on the flat surface at the base of the drop; comparable flows have been described on Kilauea. Similarly, pahoehoe breakouts from the caldera floor a'a flow were driven by pressure from the inflating flow, causing well-insulated lava to emerge from the a'a body as pahoehoe. Quenched lava collected from the incandescent breakouts have higher crystal contents than those collected closer to the vents, indicating that they experienced ~30° cooling during transport within the inflating flow. At the southern tip of the caldera floor flow, several km

  8. Father's Day dike intrusion and eruption reveals interaction between magmatic and tectonic processes at Kilauea Volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Foster, J. H.; Brooks, B. A.; Sandwell, D. T.; Poland, M.; Miklius, A.; Myer, D.; Okubo, P. G.; Patrick, M.; Wolfe, C.

    2007-12-01

    The June 17-19, 2007, Father's Day dike intrusion and eruption at Kilauea volcano brought to an end a seven- year period of steady state lava effusion at the Pu'u 'O'o vent. The event was observed by an unprecedented number of geophysical instruments, with temporary arrays of GPS and tiltmeters augmenting the continuous monitoring network. Envisat and ALOS SAR scenes were also acquired during this event and provide further information on the surface deformation as the event progressed. Fortuitously, the Envisat acquisition was during a pause in the middle of the sequence, while the ALOS PALSAR scene was acquired at the end of the sequence, allowing us to model each phase separately. Analysis of these data sets indicates that, in addition to three phases of the dike intrusion, a slow earthquake also occurred on the south flank of Kilauea. The slow earthquake apparently began near the end of the second phase of the dike intrusion. It was still underway the following day, when the third phase of the intrusion began and culminated in a small eruption. This suggests the possibility that the slow earthquake was triggered by the initial diking, and then in turn influenced the progression of the intrusion. Two of the largest previous slow earthquakes also hint at a connection between slow earthquakes and eruptive activity on Kilauea. The range of observations of the Father's Day events provides us with a unique opportunity to investigate the complex interactions between the tectonic processes of the south flank and magmatic processes within the summit and rift zones.

  9. Pre-eruption deformation caused by dike intrusion beneath Kizimen volcano, Kamchatka, Russia, observed by InSAR

    USGS Publications Warehouse

    Ji, Lingyun; Lu, Zhong; Dzurisin, Daniel; Senyukov, Sergey

    2013-01-01

    Interferometric synthetic aperture radar (InSAR) images reveal a pre-eruption deformation signal at Kizimen volcano, Kamchatka, Russia, where an ongoing eruption began in mid-November, 2010. The previous eruption of this basaltic andesite-to-dacite stratovolcano occurred in 1927–1928. InSAR images from both ascending and descending orbital passes of Envisat and ALOS PALSAR satellites show as much as 6 cm of line-of-sight shortening from September 2008 to September 2010 in a broad area centered at Kizimen. About 20 cm of opening of a nearly vertical dike provides an adequate fit to the surface deformation pattern. The model dike is approximately 14 km long, 10 km high, centered 13 km beneath Kizimen, and strikes NE–SW. Time-series analysis of multi-temporal interferograms indicates that (1) intrusion started sometime between late 2008 and July 2009, (2) continued at a nearly constant rate, and (3) resulted in a volume expansion of 3.2 × 107 m3 by September 2010, i.e., about two months before the onset of the 2010 eruption. Earthquakes located above the tip of the dike accompanied the intrusion. Eventually, magma pressure in the dike exceeded the confining strength of the host rock, triggering the 2010 eruption. Our results provide insight into the intrusion process that preceded an explosive eruption at a Pacific Rim stratovolcano following nearly a century of quiescence, and therefore have implications for monitoring and hazards assessment at similar volcanoes elsewhere.

  10. Large explosive basaltic eruptions at Katla volcano, Iceland: Fragmentation, grain size and eruption dynamics

    NASA Astrophysics Data System (ADS)

    Schmith, Johanne; Höskuldsson, Ármann; Holm, Paul Martin; Larsen, Guðrún

    2018-04-01

    Katla volcano in Iceland produces hazardous large explosive basaltic eruptions on a regular basis, but very little quantitative data for future hazard assessments exist. Here details on fragmentation mechanism and eruption dynamics are derived from a study of deposit stratigraphy with detailed granulometry and grain morphology analysis, granulometric modeling, componentry and the new quantitative regularity index model of fragmentation mechanism. We show that magma/water interaction is important in the ash generation process, but to a variable extent. By investigating the large explosive basaltic eruptions from 1755 and 1625, we document that eruptions of similar size and magma geochemistry can have very different fragmentation dynamics. Our models show that fragmentation in the 1755 eruption was a combination of magmatic degassing and magma/water-interaction with the most magma/water-interaction at the beginning of the eruption. The fragmentation of the 1625 eruption was initially also a combination of both magmatic and phreatomagmatic processes, but magma/water-interaction diminished progressively during the later stages of the eruption. However, intense magma/water interaction was reintroduced during the final stages of the eruption dominating the fine fragmentation at the end. This detailed study of fragmentation changes documents that subglacial eruptions have highly variable interaction with the melt water showing that the amount and access to melt water changes significantly during eruptions. While it is often difficult to reconstruct the progression of eruptions that have no quantitative observational record, this study shows that integrating field observations and granulometry with the new regularity index can form a coherent model of eruption evolution.

  11. Tephra architecture, pyroclast texture and magma rheology of mafic, ash-dominated eruptions: the Violent Strombolian phase of the Pleistocene Croscat (NE Spain) eruption.

    NASA Astrophysics Data System (ADS)

    Cimarelli, C.; Di Traglia, F.; Vona, A.,; Taddeucci, J.

    2012-04-01

    A broad range of low- to mid-intensity explosive activity is dominated by the emission of ash-sized pyroclasts. Among this activity, Violent Strombolian phases characterize the climax of many mafic explosive eruptions. Such phases last months to years, and produce ash-charged plumes several kilometers in height, posing severe threats to inhabited areas. To tackle the dominant processes leading to ash formation during Violent Strombolian eruptions, we investigated the magma rheology and the field and textural features of products from the 11 ka Croscat basaltic complex scoria cone in the Quaternary Garrotxa Volcanic Field (GVF). Field, grain-size, chemical (XRF, FE-SEM and electron microprobe) and textural analyses of the Croscat pyroclastic succession outlined the following eruption evolution: activity at Croscat began with fissural, Hawaiian-type fountaining that rapidly shifted towards Strombolian style from a central vent. Later, a Violent Strombolian explosion included several stages, with different emitted volumes and deposit features indicative of differences within the same eruptive style: at first, quasi-sustained fire-fountaining with ash jet and plume produced a massive, reverse to normal graded, scoria deposit; later, a long lasting series of ash-explosions produced a laminated scoria deposit. The eruption ended with a lava flow breaching the western-side of the volcano. Scoria clasts from the Croscat succession ubiquitously show micrometer- to centimeter-sized, microlite-rich domains (MRD) intermingled with volumetrically dominant, microlite-poor domains (MPD). MRD magmas resided longer in a relatively cooler, degassed zone lining the conduit walls, while MPD ones travelled faster along the central, hotter streamline, the two interminging along the interface between the two velocity zones. The preservation of two distinct domains in the short time-scale of the eruption was favoured by their rheological contrast related to the different microlite

  12. The eruption of Mount Pagan volcano, Mariana Islands, 15 May 1981

    USGS Publications Warehouse

    Banks, N.G.; Koyanagi, R.Y.; Sinton, J.M.; Honma, K.T.

    1984-01-01

    A major explosive eruption occurred 15 May 1981 at Mount Pagan Volcano, the larger of two historic eruptive centers on Pagan Island, Mariana Islands. The eruption was preceded by increased numbers of locally felt earthquakes beginning in late March or early April and by new ground cracks, new sublimates, and increased gas emissions. A swarm of felt earthquakes began at 0745h (local time = UCT+10 hours) 15 May, and at 0915 h, closely following a loud sonic boom, a strong plinian column issued from the volcano. The high-altitude ash cloud (at least 13.5 km) travelled south-southeast, but ash and scoria deposits were thickest (> 2 m) in the NW sector of the island because of the prevailing low-altitude southeasterly winds. The early activity of 15 May probably involved magmatic eruption along a fissure system oriented about N10??E. However, the eruption became hydromagmatic, possibly within minutes, and was largely restricted to three long-lived vents. The northernmost of these built a substantial new scoria-ash cinder cone. Flows and air-fall deposits, consisting almost entirely of juvenile material, exceeded 105 ?? 106 m3 in volume (75 ?? 106 m3 of magma) on land and at least 70-100 ?? 606 m3 at sea. An unknown volume was carried away by stratospheric winds. Lithic blocks and juvenile bombs as large as 1 m in diameter were thrown more than 2 km from the summit, and evidence for base-surge was observed in restricted corridors as low as 200 m elevation on the north and south slopes of the volcano. Neither of these events resulted in serious injuries to the 54 residents of the island, nor did the eruption produce serious chemical hazards in their water supply. Weak eruptions occurred during the ensuing month, and some of these were monitored by ground observations, seismic monitoring, and deformation studies. Precursory seismicity and possibly deformation occurred with some of the observed eruptions. More vigorous eruptions were reported by visiting residents in late

  13. Yohimbine-induced cutaneous drug eruption, progressive renal failure, and lupus-like syndrome.

    PubMed

    Sandler, B; Aronson, P

    1993-04-01

    Yohimbine is an indole alkaloid obtained from the yohimbe tree, a common tree in West Africa. We describe a forty-two-year black man in whom a generalized erythrodermic skin eruption, progressive renal failure, and lupus-like syndrome developed following treatment with the drug, yohimbine. A literature review failed to reveal any reported association of these side effects. We review current information on yohimbine's use in male impotence, reported side effects, and its role as a drug allergen.

  14. 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.

  15. The 2010 Eyjafjallajokull Eruptions: The NASA Applied Sciences Perspective for Aviation

    NASA Astrophysics Data System (ADS)

    Murray, J. J.; Haynes, J. A.; Trepte, C. R.; Krotkov, N. A.; Krueger, A. J.

    2010-12-01

    The volcanic ash from the eruption of the Eyjafjallajokull volcano in Iceland which began on March 17, 2010 was closely monitored by NASA Earth Observing System satellites. A wide variety of applications and techniques developed by the NASA Science Mission Directorate’s Applied Science Program were employed. These included information from imager data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua and Terra spacecraft. Horizontal distribution of the ash cloud and column amount of volcanic sufur dioxide gas was accurately mapped by the Ozone Monitoring Instrument (OMI) onboard the Aura satellite. Highly precise retrievals of the vertical distribution of volcanic aerosols were obtained by the Caliop instrument onboard the Calipso satellite. The Multi-angle Imaging SpectroRadiometer (MISR) satellite also provided stereo-derived plume heights at 1km horizontal and ~0.5km vertical resolutions. All of this information was employed to assist in airspace management during the eruptive period. It will continue to be used to improve dispersion models and procedures for dealing with volcanic ash.

  16. Primary failure of eruption: further characterization of a rare eruption disorder.

    PubMed

    Frazier-Bowers, Sylvia A; Koehler, Karen E; Ackerman, James L; Proffit, William R

    2007-05-01

    Posterior open bite has several possible causes, including primary failure of eruption (PFE) that affects all teeth distal to the most mesial involved tooth, mechanical failure of eruption (MFE) (primarily ankylosis) that affects only the involved tooth or teeth, and soft-tissue interferences with eruption (other). Radiographs and other clinical records for 97 cases of failure of posterior eruption submitted for consultation were analyzed to further characterize PFE and distinguish it from MFE. Of the 97 cases, 38 were judged to be clear-cut PFE; 19 were diagnosed as MFE; 32 were classified as indeterminate failure because they were too young to be certain of the distinction between PFE and MFE; and 8 were placed in the "other" category. Two subtypes of PFE were observed. In type 1, eruption failure occurred at or near the same time for all teeth in an affected quadrant. In type 2, a gradient of the time of failure was present, so that some further development of the teeth posterior to the most mesial affected tooth was observed before eruption failure. A family history of eruption problems was noted in 10 of the 38 PFE subjects (26%), and a pedigree analysis was done for 4 families. This was consistent with autosomal dominant transmission. The distinction between PFE and MFE is clinically important because it determines whether all posterior teeth, or only individual affected teeth, will not respond to orthodontic force. Certain diagnosis often requires progress radiographs so that the pattern of eruption of teeth distal to the most mesial affected tooth can be observed.

  17. Are Avellino (4365 cal BP) and Pompeii twin plinian eruptions? Pre-eruptive constraints and degassing history

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoît.; Ucciani, Guillaume; Cioni, Raffaello

    2010-05-01

    Somma-Vesuvius activity started 35 ky ago and is characterized by numerous eruptions of variable composition and eruptive style, sometimes interrupted by long periods of unrest. The main explosive eruptions are represented by four plinian eruptions: Pomici di Base eruption (22 cal ky), Mercato (~8900 cal BP), Avellino (4365 cal BP) and Pompeii (79 AD). The 79 AD eruption embodies the most famous eruption since it's responsible of the destruction of Pompeii and Herculanum and it's the first described eruption. The Avellino eruption represents the last plinian event that preceded the Pompeii eruption. The eruptive sequence is similar to the 79 AD plinian eruption, with an opening phase preceding a main plinian fallout activity which ended by a phreatomagmatic phase. The fallout deposit displays a sharp colour contrast from white to grey pumice, corresponding to a magma composition evolution. We focus our study on the main fallout deposit that we sampled in detail in the Traianello quarry, 9 km North-North East of the crater, to investigate the degassing processes during the eruption, using volatile content and textural observations. Density and vesicularity measurements were obtained on a minimum of 100 pumice clasts sampled in 10 stratigraphic levels in the fallout deposit. On the basis of the density distribution, bulk geochemical data, point analytical measurements on glasses (melt inclusions and residual glass) and textural observations were obtained simultaneously on a minimum of 5 pumice clasts per eruptive unit. The glass composition, in particular the Na/K ratio, evolves from Na-rich phonolite for white pumices to a more K-rich phonolite for grey pumices. The pre-eruptive conditions are constrained by systematic Cl measurements in melt inclusions and matrix glass of pumice clasts. The entire magma was saturated relative to sub-critical fluids (a Cl-rich H2O vapour phase and a brine), with a Cl melt content buffered at ~6000 ppm, and a mean pre-eruptive H2O

  18. Recent Inflation of Kilauea Volcano During the Ongoing Eruption - Harbinger of Change?

    NASA Astrophysics Data System (ADS)

    Miklius, A.

    2005-12-01

    Since the start of the Pu`u `O`o-Kupaianaha eruption on Kilauea's east rift zone in 1983, the volcano's summit has subsided over 1.5 m. Over the last two years, however, leveling and GPS networks have recorded substantial inflation of the summit magma system. Since late 2003, the summit has extended almost 20 cm and risen about 5 cm. Leveling surveys suggest that the locus of inflation has been variable, with maximum uplift shifting from an area in the caldera near Halemaumau to an area in the southeastern part of the caldera, near Keanakako`i crater. Inflation rates have also been highly variable. Starting in mid-January 2005, the inflation rate accelerated for approximately a month, with extension rates across the summit reaching over 60 cm/yr. During this accelerated inflation, on January 25, a brief inflation-deflation transient was recorded on the tiltmeter network, accompanied by volcanic tremor. This event was followed by rapid slip of Kilauea's south flank, raising intriguing possibilities about the relationship between the magmatic system and the rapid slip events. Tiltmeters at the eruption site also recorded inflation, but only until early February, when a deflationary trend began, accompanied by increased eruptive output. The summit continued to inflate until late February, deflated slightly, then resumed inflation in April. These observations suggest that the high inflation rate in January-February was a result of increased magma supply to the summit magma system. In contrast, the most recent previous episode of inflation in 2002 was related to decreased outflow at the eruption site, effectively backing up pressure in the system. That inflation episode ended with the opening of new vents on the flank of Pu`u `O`o that produced high volumes of lava. The two previous, prolonged periods of uplift at the summit were in 1985-1986, before the eruption moved downrift from Pu`u `O`o to Kupaianaha, and 1990-1992, when eruptive activity shifted back to Pu`u `O

  19. LATERAL OFFSET OF THE CORONAL MASS EJECTIONS FROM THE X-FLARE OF 2006 DECEMBER 13 AND ITS TWO PRECURSOR ERUPTIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sterling, Alphonse C.; Moore, Ronald L.; Harra, Louise K., E-mail: alphonse.sterling@nasa.gov, E-mail: ron.moore@nasa.gov, E-mail: lkh@mssl.ucl.ac.uk

    2011-12-10

    Two GOES sub-C-class precursor eruptions occurred within {approx}10 hr prior to and from the same active region as the 2006 December 13 X4.3-class flare. Each eruption generated a coronal mass ejection (CME) with center laterally far offset ({approx}> 45 Degree-Sign ) from the co-produced bright flare. Explaining such CME-to-flare lateral offsets in terms of the standard model for solar eruptions has been controversial. Using Hinode/X-Ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) data, and Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) and Michelson Doppler Imager (MDI) data, we find or infer the following. (1) The first precursormore » was a 'magnetic-arch-blowout' event, where an initial standard-model eruption of the active region's core field blew out a lobe on one side of the active region's field. (2) The second precursor began similarly, but the core-field eruption stalled in the side-lobe field, with the side-lobe field erupting {approx}1 hr later to make the CME either by finally being blown out or by destabilizing and undergoing a standard-model eruption. (3) The third eruption, the X-flare event, blew out side lobes on both sides of the active region and clearly displayed characteristics of the standard model. (4) The two precursors were offset due in part to the CME originating from a side-lobe coronal arcade that was offset from the active region's core. The main eruption (and to some extent probably the precursor eruptions) was offset primarily because it pushed against the field of the large sunspot as it escaped outward. (5) All three CMEs were plausibly produced by a suitable version of the standard model.« less

  20. Petrologic constraints on rift-zone processes - Results from episode 1 of the Puu Oo eruption of Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Garcia, M.O.; Ho, R.A.; Rhodes, J.M.; Wolfe, E.W.

    1989-01-01

    The Puu Oo eruption in the middle of Kilauea volcano's east rift zone provides an excellent opportunity to utilize petrologic constraints to interpret rift-zone processes. Emplacement of a dike began 24 hours before the start of the eruption on 3 January 1983. Seismic and geodetic evidence indicates that the dike collided with a magma body in the rift zone. Most of the lava produced during the initial episode of the Puu Oo eruption is of hybrid composition, with petrographic and geochemical evidence of mixing magmas of highly evllved and more mafic compositions. Some olivine and plagioclase grains in the hybrid lavas show reverse zoning. Whole-rock compositional variations are linear even for normally compatible elements like Ni and Cr. Leastsquares mixing calculations yield good residuals for major and trace element analyses for magma mixing. Crystal fractionation calculations yield unsatisfactory residuals. The highly evolved magma is similar in composition to the lava from the 1977 eruption and, at one point, vents for these two eruptions are only 200 m apart. Possibly both the 1977 lava and the highly evolved component of the episode 1 Puu Oo lava were derived from a common body of rift-zone-stored magma. The more mafic mixing component may be represented by the most mafic lava from the January 1983 eruption; it shows no evidence of magma mixing. The dike that was intruded just prior to the start of the Puu Oo eruption may have acted as a hydraulic plunger causing mixing of the two rift-zone-stored magmas. ?? 1989 Springer-Verlag.

  1. NEW ASPECTS OF A LID-REMOVAL MECHANISM IN THE ONSET OF AN ERUPTION SEQUENCE THAT PRODUCED A LARGE SOLAR ENERGETIC PARTICLE (SEP) EVENT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    We examine a sequence of two ejective eruptions from a single active region on 2012 January 23, using magnetograms and EUV images from the Solar Dynamics Observatory's (SDO) Helioseismic and Magnetic Imager (HMI) and Atmospheric and Imaging Assembly (AIA), and EUV images from STEREO/EUVI. This sequence produced two coronal mass ejections (CMEs) and a strong solar energetic particle event (SEP); here we focus on the magnetic onset of this important space weather episode. Cheng et al. showed that the first eruption's ({sup E}ruption 1{sup )} flux rope was apparent only in ''hotter'' AIA channels, and that it removed overlying field thatmore » allowed the second eruption ({sup E}ruption 2{sup )} to begin via ideal MHD instability; here we say that Eruption 2 began via a ''lid removal'' mechanism. We show that during Eruption 1's onset, its flux rope underwent a ''tether weakening'' (TW) reconnection with field that arched from the eruption-source active region to 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 ∼7.5 MK and 9 MK, compared to ∼14 MK). The corresponding three sequential GOES flares were, respectively, due to TW reconnection plus earlier phase Eruption 1 tether-cutting reconnection, Eruption 1 later-phase tether-cutting reconnection, and Eruption 2 tether-cutting reconnection.« less

  2. 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

  3. Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka

    PubMed Central

    Lane, Christine S.; Chorn, Ben T.; Johnson, Thomas C.

    2013-01-01

    The most explosive volcanic event of the Quaternary was the eruption of Mt. Toba, Sumatra, 75,000 y ago, which produced voluminous ash deposits found across much of the Indian Ocean, Indian Peninsula, and South China Sea. A major climatic downturn observed within the Greenland ice cores has been attributed to the cooling effects of the ash and aerosols ejected during the eruption of the Youngest Toba Tuff (YTT). These events coincided roughly with a hypothesized human genetic bottleneck, when the number of our species in Africa may have been reduced to near extinction. Some have speculated that the demise of early modern humans at that time was due in part to a dramatic climate shift triggered by the supereruption. Others have argued that environmental conditions would not have been so severe to have such an impact on our ancestors, and furthermore, that modern humans may have already expanded beyond Africa by this time. We report an observation of the YTT in Africa, recovered as a cryptotephra layer in Lake Malawi sediments, >7,000 km west of the source volcano. The YTT isochron provides an accurate and precise age estimate for the Lake Malawi paleoclimate record, which revises the chronology of past climatic events in East Africa. The YTT in Lake Malawi is not accompanied by a major change in sediment composition or evidence for substantial temperature change, implying that the eruption did not significantly impact the climate of East Africa and was not the cause of a human genetic bottleneck at that time. PMID:23630269

  4. Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka.

    PubMed

    Lane, Christine S; Chorn, Ben T; Johnson, Thomas C

    2013-05-14

    The most explosive volcanic event of the Quaternary was the eruption of Mt. Toba, Sumatra, 75,000 y ago, which produced voluminous ash deposits found across much of the Indian Ocean, Indian Peninsula, and South China Sea. A major climatic downturn observed within the Greenland ice cores has been attributed to the cooling effects of the ash and aerosols ejected during the eruption of the Youngest Toba Tuff (YTT). These events coincided roughly with a hypothesized human genetic bottleneck, when the number of our species in Africa may have been reduced to near extinction. Some have speculated that the demise of early modern humans at that time was due in part to a dramatic climate shift triggered by the supereruption. Others have argued that environmental conditions would not have been so severe to have such an impact on our ancestors, and furthermore, that modern humans may have already expanded beyond Africa by this time. We report an observation of the YTT in Africa, recovered as a cryptotephra layer in Lake Malawi sediments, >7,000 km west of the source volcano. The YTT isochron provides an accurate and precise age estimate for the Lake Malawi paleoclimate record, which revises the chronology of past climatic events in East Africa. The YTT in Lake Malawi is not accompanied by a major change in sediment composition or evidence for substantial temperature change, implying that the eruption did not significantly impact the climate of East Africa and was not the cause of a human genetic bottleneck at that time.

  5. Mechanism of Human Tooth Eruption: Review Article Including a New Theory for Future Studies on the Eruption Process

    PubMed Central

    Kjær, Inger

    2014-01-01

    Human eruption is a unique developmental process in the organism. The aetiology or the mechanism behind eruption has never been fully understood and the scientific literature in the field is extremely sparse. Human and animal tissues provide different possibilities for eruption analyses, briefly discussed in the introduction. Human studies, mainly clinical and radiological, have focused on normal eruption and gender differences. Why a tooth begins eruption and what enables it to move eruptively and later to end these eruptive movements is not known. Pathological eruption courses contribute to insight into the aetiology behind eruption. A new theory on the eruption mechanism is presented. Accordingly, the mechanism of eruption depends on the correlation between space in the eruption course, created by the crown follicle, eruption pressure triggered by innervation in the apical root membrane, and the ability of the periodontal ligament to adapt to eruptive movements. Animal studies and studies on normal and pathological eruption in humans can support and explain different aspects in the new theory. The eruption mechanism still needs elucidation and the paper recommends that future research on eruption keeps this new theory in mind. Understanding the aetiology of the eruption process is necessary for treating deviant eruption courses. PMID:24688798

  6. Ash from Kilauea Eruption Viewed by NASA's MISR

    NASA Image and Video Library

    2018-05-09

    On May 3, 2018, a new eruption began at a fissure of the Kilauea volcano on the Island of Hawaii. Kilauea is the most active volcano in the world, having erupted almost continuously since 1983. Advancing lava and dangerous sulfur dioxide gas have forced thousands of residents in the neighborhood of Leilani Estates to evacuate. A number of homes have been destroyed, and no one can say how soon the eruption will abate and evacuees can return home. On May 6, 2018, at approximately 11 a.m. local time, the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite captured this view of the island as it passed overhead. Much of the island was shrouded by clouds, including the fissure on its eastern point. However, an eruption plume is visible streaming southwest over the ocean. The MISR instrument is unique in that it has nine cameras that view Earth at different angles: one pointing downward, four at various angles in the forward direction, and four in the backward direction. This image shows the view from one of MISR's forward-pointing cameras (60 degrees), which shows the plume more distinctly than the near-vertical views. The information from the images acquired at different view angles is used to calculate the height of the plume, results of which are superimposed on the right-hand image. The top of the plume near the fissure is at approximately 6,500 feet (2,000 meters) altitude, and the height of the plume decreases as it travels south and west. These relatively low altitudes mean that the ash and sulfur dioxide remained near the ground, which can cause health issues for people on the island downwind of the eruption. The "Ocean View" air quality monitor operated by the Clean Air Branch of the State of Hawaii Department of Health recorded a concentration of 18 μg/m3 of airborne particles less than 2.5 micrometers in diameter at 11 a.m. local time. This amount corresponds to an air quality rating of "moderate" and supports the MISR results

  7. Tooth Eruption without Roots

    PubMed Central

    2013-01-01

    Root development and tooth eruption are very important topics in dentistry. However, they remain among the less-studied and -understood subjects. Root development accompanies rapid tooth eruption, but roots are required for the movement of teeth into the oral cavity. It has been shown that the dental follicle and bone remodeling are essential for tooth eruption. So far, only limited genes have been associated with root formation and tooth eruption. This may be due to the difficulties in studying late stages of tooth development and tooth movement and the lack of good model systems. Transgenic mice with eruption problems and short or no roots can be used as a powerful model for further deciphering of the cellular, molecular, and genetic mechanisms underlying root formation and tooth eruption. Better understanding of these processes can provide hints on delivering more efficient dental therapies in the future. PMID:23345536

  8. 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

  9. 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

  10. Pu'u 'Ō'ō-Kūpaianaha eruption of Kilauea, November 1991-February 1994; field data and flow maps

    USGS Publications Warehouse

    Heliker, C. Christina; Mangan, Margaret T.; Mattox, Tari N.; Kauahikaua, James P.

    1998-01-01

    The Pu'u 'Ō'ō-Kūpaianaha eruption on the east rift zone of Kīlauea, which began in January 1983, is the longest-lived rift zone eruption of the last two centuries. By 1994, a broad field of lava, nearly 1 km3 in volume and 12 km wide at the coast, had buried 87 km2 of the volcano's south flank. The initial six months of fissure eruptions (episodes 1-3) were followed by three years of episodic lava fountaining from the Pu'u 'Ō'ō vent (episodes 4–47). In July 1986, after two days of fissure eruptions up- and downrift from Pu'u 'Ō'ō (episodes 48a and 48b), the eruption shifted to a new vent, Kūpaianaha, 3.5 km downrift. For the next five-and-a-half years (episode 48), Kūpaianaha was the site of nearly continuous low-level effusion. The 49th episode occurred in November 1991, when several fissures opened between Pu'u 'Ō'ō and Kūpaianaha (see Mangan and others, 1995, Bulletin of Volcanology, v. 57, p. 127-135). This three-week-long outburst was the result of the waning output of the Kūpaianaha vent, which finally died in February 1992 (see Kauahikaua and others, 1996, Bulletin of Volcanology, v. 57, p. 641-648). The third epoch of the eruption began ten days later, when vents opened on the uprift slope of the Pu'u 'Ō'ō cone. Several flank vents erupted over the next two years (episodes 50-53). In the first year, from February 1992 through February 1993, the low-level effusion was interrupted by 21 brief pauses. These ended with the beginning of episode 53 in February 1993, and for the next year, lava effusion was continuous. Episode 53 was ongoing at the end of the interval covered by this report. During the years that Kūpaianaha was active, the Pu'u 'Ō'ō conduit gradually evolved into a crater 300 m in diameter as the conduit walls collapsed. Beginning in 1987, an active lava pond was intermittently visible in the bottom of the crater; from 1990 on, the pond was almost continuously present. The Pu'u 'Ō‘ō pond drained at the beginning of episode

  11. Entertainment Films and Video in Africa.

    ERIC Educational Resources Information Center

    Crane, Louise

    The film industry in Africa began in 1963. Since then, development has been slow because of funding problems and political restrictions. Television is available to only a fraction of the population and imported programming represents almost one-half of the programming. However, there are some successful African produced television programs. The…

  12. Ultrafast syn-eruptive degassing and ascent trigger high-energy basic eruptions.

    PubMed

    Giuffrida, Marisa; Viccaro, Marco; Ottolini, Luisa

    2018-01-09

    Lithium gradients in plagioclase are capable of recording extremely short-lived processes associated with gas loss from magmas prior to extrusion at the surface. We present SIMS profiles of the 7 Li/ 30 Si ion ratio in plagioclase crystals from products of the paroxysmal sequence that occurred in the period 2011-2013 at Mt. Etna (Italy) in an attempt to constrain the final ascent and degassing processes leading to these powerful eruptions involving basic magma. The observed Li concentrations reflect cycles of Li addition to the melt through gas flushing, and a syn-eruptive stage of magma degassing driven by decompression that finally produce significant Li depletion from the melt. Modeling the decreases in Li concentration in plagioclase by diffusion allowed determination of magma ascent timescales that are on the order of minutes or less. Knowledge of the storage depth beneath the volcano has led to the quantification of a mean magma ascent velocity of ~43 m/s for paroxysmal eruptions at Etna. The importance of these results relies on the application of methods, recently used exclusively for closed-system volcanoes producing violent eruptions, to open-conduit systems that have generally quiet eruptive periods of activity sometimes interrupted by sudden re-awakening and the production of anomalously energetic eruptions.

  13. Communicating Uncertainty to the Public During Volcanic Unrest and Eruption -A Case Study From the 2004-2005 Eruption of Mount St. Helens, USA

    NASA Astrophysics Data System (ADS)

    Gardner, C. A.; Pallister, J. S.

    2005-12-01

    The earthquake swarm beneath Mount St. Helens that began on 23 September 2004 did not initially appear different from previous swarms (none of which culminated in an eruption) that had occurred beneath the volcano since the end of the 1980-1986 eruptions. Three days into the swarm, however, a burst of larger-magnitude earthquakes indicated that this swarm was indeed different and prompted the U.S. Geological Survey's Cascades Volcano Observatory (CVO) to issue a change in alert level, the first time such a change had been issued in the Cascades in over 18 years. From then on, the unrest accelerated quickly as did the need to communicate the developing conditions to the public and public officials, often in the spotlight of intense media attention. Within three weeks of the onset of unrest, magma reached the surface. Since mid-October 2004, lava has been extruding through a glacier within the crater of Mount St. Helens, forming a 60 Mm3 dome by August 2005. The rapid onset of the eruption required a rapid ramping up of communication within and among the scientific, emergency-response and land-management communities, as well as the reestablishment of protocols that had not been rigorously tested for 18 years. Early on, daily meetings of scientists from CVO and the University of Washington's Pacific Northwest Seismograph Network were established to discuss incoming monitoring data and to develop a consensus on the likely course of activity, hazard potential and the uncertainty inherent in these forecasts. Subgroups developed scenario maps to describe the range of activity likely under different eruptive behaviors and sizes, and assessed short- and long-term probabilities of eruption, explosivity and hazardous events by employing a probability-tree methodology. Resultant consensual information has been communicated to a variety of groups using established alert levels for ground-based and aviation communities, daily updates and media briefings, postings on the

  14. The eruption of Mount Pagan volcano, Mariana Islands, 15 May 1981

    NASA Astrophysics Data System (ADS)

    Banks, Norman G.; Koyanagi, Robert Y.; Sinton, John M.; Honma, Kenneth T.

    1984-10-01

    A major explosive eruption occurred 15 May 1981 at Mount Pagan Volcano, the larger of two historic eruptive centers on Pagan Island, Mariana Islands. The eruption was preceded by increased numbers of locally felt earthquakes beginning in late March or early April and by new ground cracks, new sublimates, and increased gas emissions. A swarm of felt earthquakes began at 0745h (local time = UCT+10 hours) 15 May, and at 0915 h, closely following a loud sonic boom, a strong plinian column issued from the volcano. The high-altitude ash cloud (at least 13.5 km) travelled south-southeast, but ash and scoria deposits were thickest (> 2 m) in the NW sector of the island because of the prevailing low-altitude southeasterly winds. The early activity of 15 May probably involved magmatic eruption along a fissure system oriented about N10°E. However, the eruption became hydromagmatic, possibly within minutes, and was largely restricted to three long-lived vents. The northernmost of these built a substantial new scoria-ash cinder cone. Flows and air-fall deposits, consisting almost entirely of juvenile material, exceeded 105 × 10 6 m 3 in volume (75 × 10 6 m 3 of magma) on land and at least 70-100 × 60 6 m 3 at sea. An unknown volume was carried away by stratospheric winds. Lithic blocks and juvenile bombs as large as 1 m in diameter were thrown more than 2 km from the summit, and evidence for base-surge was observed in restricted corridors as low as 200 m elevation on the north and south slopes of the volcano. Neither of these events resulted in serious injuries to the 54 residents of the island, nor did the eruption produce serious chemical hazards in their water supply. Weak eruptions occurred during the ensuing month, and some of these were monitored by ground observations, seismic monitoring, and deformation studies. Precursory seismicity and possibly deformation occurred with some of the observed eruptions. More vigorous eruptions were reported by visiting residents in

  15. 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.

  16. 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

  17. Eruption-related lahars and sedimentation response downstream of Mount Hood: Field guide to volcaniclastic deposits along the Sandy River, Oregon

    USGS Publications Warehouse

    Pierson, Tom C.; Scott, William E.; Vallance, James W.; Pringle, Patrick T.; O'Connor, Jim; Dorsey, Rebecca; Madin, Ian

    2009-01-01

    Late Holocene dome-building eruptions at Mount Hood during the Timberline and Old Maid eruptive periods resulted in numerous dome-collapse pyroclastic flows and lahars that moved large volumes of volcaniclastic sediment into temporary storage in headwater canyons of the Sandy River. During each eruptive period, accelerated sediment loading to the river through erosion and remobilization of volcanic fragmental debris resulted in very high sediment-transport rates in the Sandy River during rain- and snowmelt-induced floods. Large sediment loads in excess of the river's transport capacity led to channel aggradation, channel widening, and change to a braided channel form in the lowermost reach of the river, between 61 and 87 km downstream from the volcano. The post-eruption sediment load moved as a broad bed-material wave, which in the case of the Old Maid eruption took ~2 decades to crest 83 km downstream. Maximum post-eruption aggradation levels of at least 28 and 23 m were achieved in response to Timberline and Old Maid eruptions. In each case, downstream aggradation cycles were initiated by lahars, but the bulk of the aggradation was achieved by fluvial sediment transport and deposition. When the high rates of sediment supply began to diminish, the river degraded, incising the channel fills and forming progressively lower sets of degradational terraces. A variety of debris-flow, hyperconcentrated-flow, and fluvial (upper and lower flow regime) deposits record the downstream passage of the sediment waves that were initiated by these eruptions. The deposits also presage a hazard that may be faced by communities along the Sandy River when volcanic activity at Mount Hood resumes.

  18. The plinian eruptions of 1912 at Novarupta, Katmai National Park, Alaska

    USGS Publications Warehouse

    Fierstein, J.; Hildreth, W.

    1992-01-01

    The three-day eruption at Novarupta in 1912 consisted of three discrete episodes. Episode I began with plinian dispersal of rhyolitic fallout (Layer A) and contemporaneous emplacement of rhyolitic ignimbrites and associated proximal veneers. The plinian column was sustained throughout most of the interval of ash flow generation, in spite of progressive increases in the proportions of dacitic and andesitic ejecta at the expense of rhyolite. Accordingly, plinian Layer B, which fell in unbroken continuity with purely rhyolitic Layer A, is zoned from >99% to ???15% rhyolite and accumulated synchronously with emplacement of the correspondingly zoned ash flow sequence in Mageik Creek and the Valley of Ten Thousand Smokes (VTTS). Only the andesiterichest flow units that cap the flow sequence lack a widespread fallout equivalent, indicating that ignimbrite emplacement barely outlasted the plinian phase. On near-vent ridges, the passing ash flows left proximal ignimbrite veneers that share the compositional zonation of their valley-filling equivalents but exhibit evidence for turbulent deposition and recurrent scour. Episode II began after a break of a few hours and was dominated by plinian dispersal of dacitic Layers C and D, punctuated by minor proximal intraplinian flows and surges. After another break, dacitic Layers F and G resulted from a third plinian episode (III); intercalated with these proximally are thin intraplinian ignimbrites and several andesite-rich fall/flow layers. Both CD and FG were ejected from an inner vent <400 m wide (nested within that of Episode I), into which the rhyolitic lava dome (Novarupta) was still later extruded. Two finer-grained ash layers settled from composite regional dust clouds: Layer E, which accumulated during the D-F hiatus, includes a contribution from small contemporaneous ash flows; and Layer H settled after the main eruption was over. Both are distinct layers in and near the VTTS, but distally they merge with CD and FG

  19. A Study of a Compound Solar Eruption with Two Consecutive Erupting Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Dhakal, Suman K.; Chintzoglou, Georgios; Zhang, Jie

    2018-06-01

    We report a study of a compound solar eruption that was associated with two consecutively erupting magnetic structures and correspondingly two distinct peaks, during impulsive phase, of an M-class flare (M8.5). Simultaneous multi-viewpoint observations from SDO, GOES and STEREO-A show that this compound eruption originated from two pre-existing sigmoidal magnetic structures lying along the same polarity inversion line. Observations of the associated pre-existing filaments further show that these magnetic structures are lying one on top of the other, separated by 12 Mm in height, in a so-called “double-decker” configuration. The high-lying magnetic structure became unstable and erupted first, appearing as an expanding hot channel seen at extreme ultraviolet wavelengths. About 12 minutes later, the low-lying structure also started to erupt and moved at an even faster speed compared to the high-lying one. As a result, the two erupting structures interacted and merged with each other, appearing as a single coronal mass ejection in the outer corona. We find that the double-decker configuration is likely caused by the persistent shearing motion and flux cancellation along the source active region’s strong-gradient polarity inversion line. The successive destabilization of these two separate but closely spaced magnetic structures, possibly in the form of magnetic flux ropes, led to a compound solar eruption. The study of the compound eruption provides a unique opportunity to reveal the formation process, initiation, and evolution of complex eruptive structures in solar active regions.

  20. Lunar mare volcanism - Stratigraphy, eruption conditions, and the evolution of secondary crusts

    NASA Technical Reports Server (NTRS)

    Head, James W., III; Wilson, Lionel

    1992-01-01

    Recent developments in the geological analysis of lunar mare volcanism are reviewed. Analysis of returned samples and photogeological and remote sensing studies shows that mare volcanism began prior to the end of heavy bombardment (the period of cryptomare formation), in pre-Nectarian times, and continued until the Copernical Period, the total duration approaching 3.5-4 Ga. Stratigraphic analysis shows that the flux was not constant, but peaked in early lunar history, during the Imbrian Period. Average volcanic output rate during this period was about 0.01 cu cm/a. Volcanic landforms indicate that many eruptions were of high volume and long duration. Some eruptions associated with sinuous rills may have lasted a year and emplaced 1000 cu km of lava, representing the equivalent in one year of about 70,000 yr at the average flux. The occurrence of farside maria within craters whose diameter is generally near to or less than the thickness of the crust may be accounted for by the difference between local and regional compensation.

  1. A Volcano Rekindled: The Renewed Eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Mount St. Helens began a dome-building eruption in September 2004 after nearly two decades of quiescence. Dome growth was initially robust, became more sluggish with time, and ceased completely in late January 2008. The volcano has been quiet again since January 2008. Professional Paper 1750 describes the first 1 1/2 years of this eruptive activity, chiefly from September 2004 until December 2005. Its 37 chapters contain contributions of 87 authors from 23 institutions, including the U.S. Geological Survey, Forest Service, many universities, and local and State emergency management agencies. Chapter topics range widely - from seismology, geology, geodesy, gas geochemistry, and petrology to the human endeavor required for managing the public volcanic lands and distributing information during the hectic early days of a renewed eruption. In PDF format, the book may be downloaded in its entirety or by its topical sections, each section including a few prefatory paragraphs that describe the general findings, recurrent themes, and, in some cases, the unanswered questions that arise repeatedly. Those readers who prefer downloading the smaller files of only a chapter or two have this option available as well. Readers are directed to chapter 1 for a general overview of the eruption and the manner in which different chapters build our knowledge of events. More detailed summaries for specific topics can be found in chapter 2 (seismology), chapter 9 (geology), chapter 14 (deformation), chapter 26 (gas geochemistry), and chapter 30 (petrology). The printed version of the book may be purchased as a hardback weighty tome (856 printed pages) that includes a DVD replete with the complete online version, including all chapters and several additional appendixes not in the printed book.

  2. The 1793 eruption of San Martín Tuxtla volcano, Veracruz, Mexico

    NASA Astrophysics Data System (ADS)

    Espíndola, J. M.; Zamora-Camacho, A.; Godinez, M. L.; Schaaf, P.; Rodríguez, S. R.

    2010-11-01

    San Martín Tuxtla (N18.562°; W95.199°, 1659 masl) is a basaltic volcano located in southern Veracruz, a Mexican State bordering the Gulf of Mexico. It rises in a volcanic field strewn with monogenetic volcanic cones, maars and three other large volcanoes mostly dormant since the late Pliocene: Santa Marta, San Martín Pajapan and Cerro El Vigía. The latest eruptive event of San Martín occurred in 1793 and was described by Don José Mariano Moziño, a naturalist under the commission of the Viceroy of the then New Spain. In this work we present results of the study of this eruption based on historical accounts and field observations. We identified an ash deposit around the volcano related to the 1793 eruption, mapped its distribution and determined its granulometric, petrographic and geochemical characteristics. These studies suggest that the volcano began its activity with explosive phreatomagmatic explosions, which were followed by Strombolian activity; this period lasting from March to October 1793. The activity continued with an effusive phase that lasted probably 2 years. The eruption covered an area of about 480 km 2 with at least 1 cm of ash; the fines reaching distances greater than 300 km from the crater. A total mass of about 2.5 × 10 14 g was ejected and the volcanic columns probably reached altitudes of the order of 10 km during the most explosive phases. The lava emitted formed a coulee that descended the northern flank of the volcano and has an approximate volume of 2.0 × 10 7 m 3.

  3. Keanakākoʻi Tephra produced by 300 years of explosive eruptions following collapse of Kīlauea's caldera in about 1500 CE

    USGS Publications Warehouse

    Swanson, Donald A.; Rose, Timothy R.; Fiske, Richard S.; McGeehin, John P.

    2012-01-01

    The Keanakākoʻi Tephra at Kīlauea Volcano has previously been interpreted by some as the product of a caldera-forming eruption in 1790 CE. Our study, however, finds stratigraphic and 14C evidence that the tephra instead results from numerous eruptions throughout a 300-year period between about 1500 and 1800. The stratigraphic evidence includes: (1) as many as six pure lithic ash beds interleaved in sand dunes made of earlier Keanakākoʻi vitric ash, (2) three lava flows from Kīlauea and Mauna Loa interbedded with the tephra, (3) buried syneruptive cultural structures, (4) numerous intraformational water-cut gullies, and (5) abundant organic layers rich in charcoal within the tephra section. Interpretation of 97 new accelerator mass spectrometry (AMS) 14C ages and 4 previous conventional ages suggests that explosive eruptions began in 1470–1510 CE, and that explosive activity continued episodically until the early 1800s, probably with two periods of quiescence lasting several decades. Kīlauea's caldera, rather than forming in 1790, predates the first eruption of the Keanakākoʻi and collapsed in 1470–1510, immediately following, and perhaps causing, the end of the 60-year-long, 4–6 km3 ʻAilāʻau eruption from the east side of Kīlauea's summit area. The caldera was several hundred meters deep when the Keanakākoʻi began erupting, consistent with oral tradition, and probably had a volume of 4–6 km3. The caldera formed by collapse, but no eruption of lava coincided with its formation. A large volume of magma may have quickly drained from the summit reservoir and intruded into the east rift zone, perhaps in response to a major south-flank slip event, leading to summit collapse. Alternatively, magma may have slowly drained from the reservoir during the prolonged ʻAilāʻau eruption, causing episodic collapses before the final, largest downdrop took place. Two prolonged periods of episodic explosive eruptions are known at Kīlauea, the Keanak

  4. Keanakākoʻi Tephra produced by 300 years of explosive eruptions following collapse of Kīlauea's caldera in about 1500 CE

    USGS Publications Warehouse

    Swanson, Donald A.; Rose, Timothy R.; Fiske, Richard S.; McGeehin, John P.

    2012-01-01

    The Keanakākoʻi Tephra at Kīlauea Volcano has previously been interpreted by some as the product of a caldera-forming eruption in 1790 CE. Our study, however, finds stratigraphic and 14C evidence that the tephra instead results from numerous eruptions throughout a 300-year period between about 1500 and 1800. The stratigraphic evidence includes: (1) as many as six pure lithic ash beds interleaved in sand dunes made of earlier Keanakākoʻi vitric ash, (2) three lava flows from Kīlauea and Mauna Loa interbedded with the tephra, (3) buried syneruptive cultural structures, (4) numerous intraformational water-cut gullies, and (5) abundant organic layers rich in charcoal within the tephra section. Interpretation of 97 new accelerator mass spectrometry (AMS) 14C ages and 4 previous conventional ages suggests that explosive eruptions began in 1470–1510 CE, and that explosive activity continued episodically until the early 1800s, probably with two periods of quiescence lasting several decades. Kīlauea's caldera, rather than forming in 1790, predates the first eruption of the Keanakākoʻi and collapsed in 1470–1510, immediately following, and perhaps causing, the end of the 60-year-long, 4–6 km3 ʻAilāʻau eruption from the east side of Kīlauea's summit area. The caldera was several hundred meters deep when the Keanakākoʻi began erupting, consistent with oral tradition, and probably had a volume of 4–6 km3. The caldera formed by collapse, but no eruption of lava coincided with its formation. A large volume of magma may have quickly drained from the summit reservoir and intruded into the east rift zone, perhaps in response to a major south-flank slip event, leading to summit collapse. Alternatively, magma may have slowly drained from the reservoir during the prolonged ʻAilāʻau eruption, causing episodic collapses before the final, largest downdrop took place. Two prolonged periods of episodic explosive eruptions are known at Kīlauea, the Keanak

  5. DAMAGE AND CORRESPOBDENCE OF LOCAL GOVERNMENTS AND BUSINESS ESTABLISHMENTS FOR Mt. SHINMOE 2011 ERUPTIONS

    NASA Astrophysics Data System (ADS)

    Uno, Kohji; Nakano, Susumu; Kasubuchi, Yoshio

    On Jan. 27, 2011, Mt. Shinmoe in the Kirishima mountain range on the border between Kagoshima and Miyazaki Prefectures began erupting for the first time in 52 years. In this study, to clarify the damage and correspondence of local governments and business establishments for a series of volcanic hazards of Mt. Shinmoe in 2011, we conducted interview research and document investigation. For endless volcanic hazard, not only the serious and sustained effots of disaster-affected area, but also the broad-based supoorts from neighboring local governments and business establishments are required.

  6. Multiple coincident eruptive seismic tremor sources during the 2014-2015 eruption at Holuhraun, Iceland

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Bean, Christopher J.; Jónsdóttir, Ingibjörg; Höskuldsson, Armann; Thordarson, Thorvaldur; Coppola, Diego; Witt, Tanja; Walter, Thomas R.

    2017-04-01

    We analyze eruptive tremor during one of the largest effusive eruptions in historical times in Iceland (2014/2015 Holuhraun eruption). Seismic array recordings are compared with effusion rates deduced from Moderate Resolution Imaging Spectroradiometer recordings and ground video monitoring data and lead to the identification of three coexisting eruptive tremor sources. This contrasts other tremor studies that generally link eruptive tremor to only one source usually associated with the vent. The three sources are (i) a source that is stable in back azimuth and shows bursts with ramp-like decrease in amplitude at the beginning of the eruption: we link it to a process below the open vents where the bursts correlate with the opening of new vents and temporary increases in the lava fountaining height; (ii) a source moving by a few degrees per month while the tremor amplitude suddenly increases and decreases: back azimuth and slowness correlate with the growing margins of the lava flow field, whilst new contact with a river led to fast increases of the tremor amplitude; and (iii) a source moving by up to 25° southward in 4 days that cannot be related to any observed surface activity and might be linked to intrusions. We therefore suggest that eruptive tremor amplitudes/energies are used with caution when estimating eruptive volumes, effusion rates, or the eruption explosivity as multiple sources can coexist during the eruption phase. Our results suggest that arrays can monitor both the growth of a lava flow field and the activity in the vents.

  7. Quantifying Sulphur Emissions and Atmospheric Aerosol Loading From the 1730-36 Lanzarote Eruption

    NASA Astrophysics Data System (ADS)

    Sharma, K.; Blake, S.; Self, S.

    2005-12-01

    The AD 1730-36 eruption of Lanzarote (Canary Islands) is the third largest basaltic fissure eruption known to have occurred in the last 1000 years, after the Icelandic events of Laki (AD 1783-84) and Eldgja (AD 934). Our new volume estimates suggest that the Lanzarote eruption produced ~6 km3 of alkali basalt magma along a 15-km long, E-W trending fissure. Eruptive activity occurred in five distinct phases. Each phase began with Strombolian fire fountain activity, building large spatter and scoria cones. This was accompanied and followed by effusive aa and pahoehoe lava flow emplacement. As studies in Iceland have shown, this type of sustained fissure eruption can release large amounts of SO2 to the upper atmosphere, leading to the formation of sulphate aerosol clouds and causing widespread environmental damage and human suffering. Matrix glasses in scoria and surface lava samples have 80-300 ppm S (EMPA) and 300-600 ppm H2O (FTIR), whereas glass inclusions in olivine have 420-2650 ppm S and 1000-5000 ppm H2O. Low sulphur inclusions are believed to be partially degassed, representing melt that was trapped during degassing-induced crystallization that occurred as a result of shallow decompression. The inclusions with the highest sulphur contents trap the original un-degassed melt, as indicated by their consistent S/K2O ratio (0.22). The high sulphur contents are also consistent with our finding, from olivine-spinel equilibria, that the magma was relatively oxidized (log fO2 -4.8) therefore favouring the formation of sulphate species and preventing sulphide saturation. Our glass analyses indicate that 40 Mt of SO2 was injected into the upper troposphere - lower stratosphere via 12-16-km-high eruption plumes and that over half this amount was released during the first year of activity. This figure correlates with published Greenland ice-core (GISP-2) data that shows an acidity spike in 1731, suggesting stratospheric transport of sulphate aerosol to the North during

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

    USGS Publications Warehouse

    Miller, C. Dan; Sushyar, R.; ,; 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.

  9. 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.

  10. SYMPATHETIC SOLAR FILAMENT ERUPTIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Rui; Liu, Ying D.; Zimovets, Ivan

    2016-08-10

    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 filamentmore » 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.« less

  11. Modeling the Climate Response of the Laki Eruption - Benjamin Franklin was Right

    NASA Astrophysics Data System (ADS)

    Oman, L.; Robock, A.; Stenchikov, G. L.; Thordarson, T.

    2006-12-01

    Benjamin Franklin was one of the first to recognize the connections between volcanic eruptions and climate. Shortly after the 1783-1784 Laki eruption, he postulated that the dry fog over much of Europe was likely caused by a volcanic eruption in Iceland, that the winds would have transported the gas and aerosol over much of the Northern Hemisphere, and that the cold winter of 1783-84 was caused by this dry fog. We used the NASA Goddard Institute for Space Studies ModelE climate model to examine the chemical conversion and transport of SO2 gas from the Laki eruption (64.10°N, 17.15°W) and used the resulting aerosol concentrations to model the climate response. Using our calculated aerosol distribution, we conducted a 10-member ensemble simulation with ModelE coupled to a q-flux mixed-layer ocean. The mean of these runs reproduced the extensive radiative cooling (-1 to -3°C) that occurred during the summer of 1783 across much of Asia, Canada, and Alaska and produced a strong dynamical effect in summer as the Laki eruption forces a significant weakening of the African and India monsoon circulations. This is seen in cloud cover and precipitation anomalies and resulted in significant warming (1 to 2°C) from the Sahel of Africa to northern India. This is a very robust result and has been observed after the last 3 large high-latitude volcanic eruptions, Eldgjá (939), Katmai (1912), and Laki, all of which produced large reductions in the flow of the Nile River. In the winter of 1783-1784 our model reproduced the significant negative temperature anomalies over the Northeastern United States, and smaller cooling produced over Europe. That winter was one of the coldest on record over these areas and our model results confirm that Laki could have been partially responsible for these anomalies.

  12. Early prediction of eruption site using lightning location data: Estimates of accuracy during past eruptions

    NASA Astrophysics Data System (ADS)

    Nína Petersen, Guðrún; Arason, Þórður; Bjornsson, Halldór

    2013-04-01

    Eruption of subglacial volcanoes may lead to catastrophic floods and therefore early determination of the exact eruption site may be critical to civil protection evacuation plans. Poor visibility due to weather or darkness often inhibit positive identification of exact eruption location for many hours. However, because of the proximity and abundance of water in powerful subglacial volcanic eruptions, they are probably always accompanied by early lightning activity in the volcanic column. Lightning location systems, designed for weather thunderstorm monitoring, based on remote detection of electromagnetic waves from lightning, can provide valuable real-time information on location of eruption site. Important aspect of such remote detection is its independence of weather, apart from thunderstorms close to the volcano. Individual lightning strikes can be 5-10 km in length and are sometimes tilted and to the side of the volcanic column. This adds to the lightning location uncertainty, which is often a few km. Furthermore, the volcanic column may be swayed by the local wind to one side. Therefore, location of a single lightning can be misleading but by calculating average location of many lightning strikes and applying wind correction a more accurate eruption site location can be obtained. In an effort to assess the expected accuracy, the average lightning locations during the past five volcanic eruptions in Iceland (1998-2011) were compared to the exact site of the eruption vent. Simultaneous weather thunderstorms might have complicated this analysis, but there were no signs of ordinary thunderstorms in Iceland during these eruptions. To identify a suitable wind correction, the vector wind at the 500 hPa pressure level (5-6 km altitude) was compared to mean lightning locations during the eruptions. The essential elements of a system, which predicts the eruption site during the first hour(s) of an eruption, will be described.

  13. Multi-disciplinary Monitoring of the 2014 Eruption of Fogo Volcano, Cape Verde

    NASA Astrophysics Data System (ADS)

    Fernandes, R. M. S.; Faria, B. V. E.

    2015-12-01

    The Fogo volcano, located in the Cape Verde Archipelago (offshore Western Africa), is a complete stratovolcano system. It is the most recent expression of the Cape Verde hotspot, that has formed the archipelago. The summit reaches ~2830m above sea level, and raises 1100m above Chã das Caldeiras, an almost flat circular area. The last eruption of Fogo started on November 23, 2014 (~10:00UTC), after 19 years of inactivity. C4G, a distributed research infrastructure created in 2014 in the framework of the Portuguese Roadmap for Strategic Research Infrastructures, collaborated immediately with INMG, the Cape Verdean Meteorological and Geophysical Institut with the goal of complementing the permanent geophysical monitoring network in operation on Fogo island. The INMG permanent network is composed of seven seismographic stations and three tiltmeter stations, with real-time data transmitted. On the basis of increased pre-event activity (which started in October 2014), INMG issued a formal alert of an impending eruption to the Civil Protection Agency, about 24 hours before the onset of the eruption. Although the eruption caused no casualties or personal injuries due to the warnings issued, the lava expelled by the eruption (which last until the end of January) destroyed the two main villages in the caldera (~1000 inhabitants) and covered vast areas of agricultural land, causing very large economic losses and an uncertain future of the local populations. The C4G team installed a network of seven GNSS receivers and nine seismometers, distributed by the entire island. The data collection started on 28th November 2014, and continued until the end of January 2015. The mission also included a new detailed gravimetric survey of the island, the acquisition of geological samples, and the analysis of the air quality during the eruption. We present here a detailed description of the monitoring efforts carried out during the eruption as well as initial results of the analysis of the

  14. Two-step solar filament eruptions

    NASA Astrophysics Data System (ADS)

    Filippov, B.

    2018-04-01

    Coronal mass ejections (CMEs) are closely related to eruptive filaments and usually are the continuation of the same eruptive process into the upper corona. There are failed filament eruptions when a filament decelerates and stops at some greater height in the corona. Sometimes the filament after several hours starts to rise again and develops into the successful eruption with a CME formation. We propose a simple model for the interpretation of such two-step eruptions in terms of equilibrium of a flux rope in a two-scale ambient magnetic field. The eruption is caused by a slow decrease of the holding magnetic field. The presence of two critical heights for the initiation of the flux-rope vertical instability allows the flux rope to stay after the first jump some time in a metastable equilibrium near the second critical height. If the decrease of the ambient field continues, the next eruption step follows.

  15. 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.

  16. Observations of the eruptions of July 22 and August 7, 1980, at Mount St. Helens, Washington

    USGS Publications Warehouse

    Hoblitt, Richard P.

    1986-01-01

    The explosive eruptions of July 22 and August 7, 1980, at Mount St. Helens, Wash., both included multiple eruptive pulses. The beginnings of three of the pulses-two on July 22 and one on August 7-were witnessed and photographed. Each of these three began with a fountain of gases and pyroclasts that collapsed around the vent and generated a pyroclastic density flow. Significant vertical-eruption columns developed only after the density flows were generated. This behavior is attributable to either an increase in the gas content of the eruption jet or a decrease in vent radius with time. An increase in the gas content may have occurred as the vent was cleared (by expulsion of a plug of pyroclasts) or as the eruption began to tap deeper, gas-rich magma after first expelling the upper, gas-depleted part of the magma body. An effective decrease of the vent radius with time may have occurred as the eruption originated from progressively deeper levels in the vent. All of these processes-vent clearing; tapping of deeper, gas-rich magma; and effective decrease in vent radius-probably operated to some extent. A 'relief-valve' mechanism is proposed here to account for the occurrence of multiple eruptive pulses. This mechanism requires that the conduit above the magma body be filled with a bed of pyroclasts, and that the vesiculation rate in the magma body be inadequate to sustain continuous eruption. During a repose interval, vesiculation of the magma body would cause gas to flow upward through the bed of pyroclasts. If the rate at which the magma produced gas exceeded the rate at which gas escaped to the atmosphere, the vertical pressure difference across the bed of pyroclastic debris would increase, as would the gas-flow rate. Eventually a gas-flow rate would be achieved that would suddenly diminish the ability of the bed to maintain a pressure difference between the magma body and the atmosphere. The bed of pyroclasts would then be expelled (that is, the relief valve would

  17. 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.

  18. Dental eruption sequence among colobine primates.

    PubMed

    Harvati, K

    2000-05-01

    Dental development is one aspect of growth that is linked to diet and to life history but has not been investigated among colobines since the work of Schultz [1935]. This study establishes the dental eruption sequence for several colobine species and compares it to that of other catarrhines. The mandibles and maxillae of two hundred and four juvenile colobine specimens were scored for presence or absence of permanent teeth and for stages of partial eruption. Eruption was defined as ranging between tooth emergence (any part of a tooth crown above the alveolar margin) and full occlusion, with three intermediate levels manifest between these boundaries. In African colobines, represented by C. guereza, C. angolensis and P. badius, M2 erupts before I2, and in C. angolensis it also erupts before I1. The canine is delayed, erupting after the premolars in females and after M3 in males. Asian colobines show greater diversity in eruption sequences. Nasalis shows no early eruption of the molars and is very similar to Macaca. In Trachypithecus and Pygathrix M(2) erupts before I(2). The canine in Trachypithecus is delayed, erupting after the premolars and, in some males, after M3. In Presbytis M2 erupts before both incisors; M3 erupts before C in both sexes, and often before both premolars. Although the actual timing of eruption is unknown, all colobine species examined except N. larvatus showed some degree of relatively early eruption of M2 and M3. The lack of this tendency in Nasalis sets this genus apart from all other colobines represented in this study. Dental eruption sequence is thought to reflect life history patterns. Early molar eruption in colobines was thought by Schultz (1935) to be a primitive character reflecting shorter life history. Faster growth rates found in folivorous primates have been interpreted as being related to an adaptation to folivory (Leigh 1994), and early eruption of molars may be part of this dietary specialization. The relationships between

  19. Decompression Induced Crystallization of Basaltic Andesite Magma: Constraints on the Eruption of Arenal Volcano, Costa Rica.

    NASA Astrophysics Data System (ADS)

    Szramek, L. A.; Gardner, J. E.; Larsen, J. F.

    2004-12-01

    Arenal Volcano is a small stratovolcano located 90 km NW of San Jose, Costa Rica. In 1968 current activity began with a Plinian phase, and has continued to erupt lava flows and pyroclastic flows intermittently since. Samples from the Plinian, pyroclastic flow, strombolian, and effusive phases have been studied texturally. Little variation in crystallinity occurs amongst the different phases. Number density of crystals, both 2D and 3D are 50-70 mm-2 and 30,000-50,000 mm-3 in the Plinian sample, compared to the lesser values in other eruptive types. Characteristic crystal size also increases as explosivity decreases. Two samples, both lava flows collected while warm, overlap with the Plinian sample. This suggests that the variations seen may be a result of cooling history. Plagioclase differs between the Plinian sample, in which they are only tabular in shape, and the other eruptive types, which contain both tabular and equant crystals. To link decompression paths of the Arenal magma to possible pre-eruptive conditions, we have carried out hydrothermal experiments. The experiments were preformed in TZM pressure vessels buffered at a fugacity of Ni-NiO and water saturation. Phase equilibria results in conjunction with mineral compositions and temperature estimates by previous workers from active lava flows and two-pyroxene geothermometry, constrain the likely pre-eruptive conditions for the Arenal magma to 950-1040° C with a water pressure of 50-80 MPa. Samples that started from conditions that bracket our estimated pre-eruptive conditions were decompressed in steps of 5-30 MPa and held for various times at each step until 20 MPa was reached, approximating average decompression rates of 0.25, 0.025, 0.0013 MPa/s. Comparison of textures found in the natural samples to the experimentally produced textures suggest that the Plinian eruption likely was fed by magma ascending at 0.05-1 m/s, whereas the less explosive phases were fed by magma ascending at 0.05 m/s or less.

  20. Relationship between eruption plume heights and seismic source amplitudes of eruption tremors and explosion events

    NASA Astrophysics Data System (ADS)

    Mori, A.; Kumagai, H.

    2016-12-01

    It is crucial to analyze and interpret eruption tremors and explosion events for estimating eruption size and understanding eruption phenomena. Kumagai et al. (EPS, 2015) estimated the seismic source amplitudes (As) and cumulative source amplitudes (Is) for eruption tremors and explosion events at Tungurahua, Ecuador, by the amplitude source location (ASL) method based on the assumption of isotropic S-wave radiation in a high-frequency band (5-10 Hz). They found scaling relations between As and Is for eruption tremors and explosion events. However, the universality of these relations is yet to be verified, and the physical meanings of As and Is are not clear. In this study, we analyzed the relations between As and Is for eruption tremors and explosion events at active volcanoes in Japan, and estimated As and Is by the ASL method. We obtained power-law relations between As and Is, in which the powers were different between eruption tremors and explosion events. These relations were consistent with the scaling relations at Tungurahua volcano. Then, we compared As with maximum eruption plume heights (H) during eruption tremors analyzed in this study, and found that H was proportional to 0.21 power of As. This relation is similar to the plume height model based on the physical process of plume rise, which indicates that H is proportional to 0.25 power of volumetric flow rate for plinian eruptions. This suggests that As may correspond to volumetric flow rate. If we assume a seismic source with volume changes and far-field S-wave, As is proportional to the source volume rate. This proportional relation and the plume height model give rise to the relation that H is proportional to 0.25 power of As. These results suggest that we may be able to estimate plume heights in realtime by estimating As during eruptions from seismic observations.

  1. Breaking the Habit: The Peculiar 2016 Eruption of the Unique Recurrent Nova M31N 2008-12a

    NASA Astrophysics Data System (ADS)

    Henze, M.; Darnley, M. J.; Williams, S. C.; Kato, M.; Hachisu, I.; Anupama, G. C.; Arai, A.; Boyd, D.; Burke, D.; Ciardullo, R.; Chinetti, K.; Cook, L. M.; Cook, M. J.; Erdman, P.; Gao, X.; Harris, B.; Hartmann, D. H.; Hornoch, K.; Horst, J. Chuck; Hounsell, R.; Husar, D.; Itagaki, K.; Kabashima, F.; Kafka, S.; Kaur, A.; Kiyota, S.; Kojiguchi, N.; Kučáková, H.; Kuramoto, K.; Maehara, H.; Mantero, A.; Masci, F. J.; Matsumoto, K.; Naito, H.; Ness, J.-U.; Nishiyama, K.; Oksanen, A.; Osborne, J. P.; Page, K. L.; Paunzen, E.; Pavana, M.; Pickard, R.; Prieto-Arranz, J.; Rodríguez-Gil, P.; Sala, G.; Sano, Y.; Shafter, A. W.; Sugiura, Y.; Tan, H.; Tordai, T.; Vraštil, J.; Wagner, R. M.; Watanabe, F.; Williams, B. F.; Bode, M. F.; Bruno, A.; Buchheim, B.; Crawford, T.; Goff, B.; Hernanz, M.; Igarashi, A. S.; José, J.; Motta, M.; O’Brien, T. J.; Oswalt, T.; Poyner, G.; Ribeiro, V. A. R. M.; Sabo, R.; Shara, M. M.; Shears, J.; Starkey, D.; Starrfield, S.; Woodward, C. E.

    2018-04-01

    Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multiwavelength properties: (i) from a faint peak, the optical light curve declined rapidly by two magnitudes in less than two days, (ii) early spectra showed initial high velocities that slowed down significantly within days and displayed clear He/N lines throughout, and (iii) the supersoft X-ray source (SSS) phase of the nova began extremely early, six days after eruption, and only lasted for about two weeks. In contrast, the peculiar 2016 eruption was clearly different. Here we report (i) the considerable delay in the 2016 eruption date, (ii) the significantly shorter SSS phase, and (iii) the brighter optical peak magnitude (with a hitherto unobserved cusp shape). Early theoretical models suggest that these three different effects can be consistently understood as caused by a lower quiescence mass accretion rate. The corresponding higher ignition mass caused a brighter peak in the free–free emission model. The less massive accretion disk experienced greater disruption, consequently delaying the re-establishment of effective accretion. Without the early refueling, the SSS phase was shortened. Observing the next few eruptions will determine whether the properties of the 2016 outburst make it a genuine outlier in the evolution of M31N 2008-12a.

  2. Large Prominence Eruption [video

    NASA Image and Video Library

    2014-10-07

    The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs. Credit: NASA/Goddard/STEREO The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs.

  3. Human Footprints in Relation to the 1790 Eruption of Kilauea

    NASA Astrophysics Data System (ADS)

    Swanson, D. A.; Rausch, J.

    2008-12-01

    stream, because its fallout was mainly dispersed east-southeastward by westerlies, a wind direction found only at high altitudes in Hawai'i. Surges associated with the high eruption column swept over the southwest and west rims of the caldera. These relations indicate that the accretionary lapilli (footprints) ash was an early stage of a powerful eruption involving both high columns and lithic surges. Hawaiian oral tradition says that the 1790 eruption was large, and Jaggar calculated a column height probably greater than 9 km (30,000 ft) based on observations of a pillar (eruption column) seen over Mauna Loa when viewed from the north. This is about halfway through the jet stream. Our work found two deposits of the late 1700s dispersed east of Kilauea's summit. The younger was probably erupted in 1790. A reconstruction of events in 1790 suggests that the accretionary lapilli ash fell early in the eruption, blown southwestward into areas where family groups, mainly women and children, were chipping glass from old pahoehoe for tools. They probably sought shelter while the ash was falling. but once it stopped, they slogged through the mud, leaving footprints in the 2-cm-thick deposit.. Meanwhile, the warriors and their families, camped at Kilauea's summit (supposedly for 3 days) waiting for the eruption to end, saw the sky clear following the ash eruption and started walking southwestward along the west side of the summit area. Then the most powerful stage of the eruption began, sending surges westward across the path of the doomed group, killing many. Afterwards, any survivors or rescuers who walked on the accretionary lapilli ash, by now dry, left no footprints that are preserved.

  4. Io - Volcanic Eruption

    NASA Technical Reports Server (NTRS)

    1979-01-01

    This photo of a volcanic eruption on Jupiter's satellite Io (dark fountain-like feature near the limb) was taken March 4, 1979, about 12 hours before Voyager 1's closest approach to Jupiter. This and the accompanying photo present the evidence for the first active volcanic eruption ever observed on another body in the solar system. This photo taken from a distance of 310,000 miles (499,000 kilometers), shows a plume-like structure rising more than 60 miles (100 kilometers) above the surface, a cloud of material being produced by an active eruption. At least four eruptions have been identified on Voyager 1 pictures and many more may yet be discovered on closer analysis. On a nearly airless body like Io, particulate material thrown out of a volcano follows a ballistic trajectory, accounting for the dome-like shape of the top of the cloud, formed as particles reach the top of their flight path and begin to fall back. Spherical expansion of outflowing gas forms an even larger cloud surrounding the dust. Several regions have been identified by the infrared instrument on Voyager 1 as being several hundred degrees Fahrenheit warmer than surrounding terrain, and correlated with the eruptions. The fact that several eruptions appear to be going on simultaneously makes Io the most active surface in the solar system and suggests to scientists that Io is undergoing continuous volcanism, revising downward the age of Io's surface once again. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

  5. Plagioclase populations and zoning in dacite of the 2004-2005 Mount St. Helens eruption: constraints for magma origin and dynamics: Chapter 34 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Streck, Martin J.; Broderick, Cindy A.; Thronber, Carl R.; Clynne, Michael A.; Pallister, John S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    We propose that crystals with no dissolution surfaces are those that were supplied last to the shallow reservoir, whereas plagioclase with increasingly more complex zoning patterns (that is, the number of zoned bands bounded by dissolution surfaces) result from prolonged residency and evolution in the reservoir. We propose that banding and An zoning across multiple bands are primarily a response to thermally induced fluctuations in crystallinity of the magma in combination with recharge; a lesser role is ascribed to cycling crystals through pressure gradients. Crystals without dissolution surfaces, in contrast, could have grown only in response to steady(?) decompression. Some heating-cooling cycles probably postdate the final eruption in 1986. They resulted from small recharge events that supplied new crystals that then experienced resorption-growth cycles. We suggest that magmatic events shortly prior to the current eruption, recorded in the outermost zones of plagioclase phenocrysts, began with the incorporation of acicular orthopyroxene, followed by last resorption, and concluded with crystallization of euhedral rims. Finally, we propose that 2004-5 dacite is composed mostly of dacite magma that remained after 1986 and underwent subsequent magmatic evolution but, more importantly, contains a component of new dacite from deeper in the magmatic system, which may have triggered the new eruption.

  6. Quantifying the condition of eruption column collapse during explosive volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Koyaguchi, Takehiro; Suzuki, Yujiro

    2016-04-01

    During an explosive eruption, a mixture of pyroclasts and volcanic gas forms a buoyant eruption column or a pyroclastic flow. Generation of a pyroclastic flow caused by eruption column collapse is one of the most hazardous phenomena during explosive volcanic eruptions. The quantification of column collapse condition (CCC) is, therefore, highly desired for volcanic hazard assessment. Previously the CCC was roughly predicted by a simple relationship between magma discharge rate and water content (e.g., Carazzo et al., 2008). When a crater is present above the conduit, because of decompression/compression process inside/above the crater, the CCC based on this relationship can be strongly modified (Woods and Bower, 1995; Koyaguchi et al., 2010); however, the effects of the crater on CCC has not been fully understood in a quantitative fashion. Here, we have derived a semi-analytical expression of CCC, in which the effects of the crater is taken into account. The CCC depends on magma properties, crater shape (radius, depth and opening angle) as well as the flow rate at the base of crater. Our semi-analytical CCC expresses all these dependencies by a single surface in a parameter space of the dimensionless magma discharge rate, the dimensionless magma flow rate (per unit area) and the ratio of the cross-sectional areas at the top and the base of crater. We have performed a systematic parameter study of three-dimensional (3D) numerical simulations of eruption column dynamics to confirm the semi-analytical CCC. The results of the 3D simulations are consistent with the semi-analytical CCC, while they show some additional fluid dynamical features in the transitional state (e.g., partial column collapse). Because the CCC depends on such many parameters, the scenario towards the generation of pyroclastic flow during explosive eruptions is considered to be diverse. Nevertheless, our semi-analytical CCC together with the existing semi-analytical solution for the 1D conduit flow

  7. The largest volcanic eruptions on Earth

    NASA Astrophysics Data System (ADS)

    Bryan, Scott E.; Peate, Ingrid Ukstins; Peate, David W.; Self, Stephen; Jerram, Dougal A.; Mawby, Michael R.; Marsh, J. S. (Goonie); Miller, Jodie A.

    2010-10-01

    Large igneous provinces (LIPs) are sites of the most frequently recurring, largest volume basaltic and silicic eruptions in Earth history. These large-volume (> 1000 km 3 dense rock equivalent) and large-magnitude (> M8) eruptions produce areally extensive (10 4-10 5 km 2) basaltic lava flow fields and silicic ignimbrites that are the main building blocks of LIPs. Available information on the largest eruptive units are primarily from the Columbia River and Deccan provinces for the dimensions of flood basalt eruptions, and the Paraná-Etendeka and Afro-Arabian provinces for the silicic ignimbrite eruptions. In addition, three large-volume (675-2000 km 3) silicic lava flows have also been mapped out in the Proterozoic Gawler Range province (Australia), an interpreted LIP remnant. Magma volumes of > 1000 km 3 have also been emplaced as high-level basaltic and rhyolitic sills in LIPs. The data sets indicate comparable eruption magnitudes between the basaltic and silicic eruptions, but due to considerable volumes residing as co-ignimbrite ash deposits, the current volume constraints for the silicic ignimbrite eruptions may be considerably underestimated. Magma composition thus appears to be no barrier to the volume of magma emitted during an individual eruption. Despite this general similarity in magnitude, flood basaltic and silicic eruptions are very different in terms of eruption style, duration, intensity, vent configuration, and emplacement style. Flood basaltic eruptions are dominantly effusive and Hawaiian-Strombolian in style, with magma discharge rates of ~ 10 6-10 8 kg s -1 and eruption durations estimated at years to tens of years that emplace dominantly compound pahoehoe lava flow fields. Effusive and fissural eruptions have also emplaced some large-volume silicic lavas, but discharge rates are unknown, and may be up to an order of magnitude greater than those of flood basalt lava eruptions for emplacement to be on realistic time scales (< 10 years). Most

  8. Compound-specific carbon isotopes from Earth’s largest flood basalt eruptions directly linked to the end-Triassic mass extinction

    PubMed Central

    Whiteside, Jessica H.; Olsen, Paul E.; Eglinton, Timothy; Brookfield, Michael E.; Sambrotto, Raymond N.

    2010-01-01

    A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO2. The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie’s Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO2 super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date. PMID:20308590

  9. Monitoring lava-dome growth during the 2004-2008 Mount St. Helens, Washington, eruption using oblique terrestrial photography

    USGS Publications Warehouse

    Major, J.J.; Dzurisin, D.; Schilling, S.P.; Poland, Michael P.

    2009-01-01

    We present an analysis of lava dome growth during the 2004–2008 eruption of Mount St. Helens using oblique terrestrial images from a network of remotely placed cameras. This underutilized monitoring tool augmented more traditional monitoring techniques, and was used to provide a robust assessment of the nature, pace, and state of the eruption and to quantify the kinematics of dome growth. Eruption monitoring using terrestrial photography began with a single camera deployed at the mouth of the volcano's crater during the first year of activity. Analysis of those images indicates that the average lineal extrusion rate decayed approximately logarithmically from about 8 m/d to about 2 m/d (± 2 m/d) from November 2004 through December 2005, and suggests that the extrusion rate fluctuated on time scales of days to weeks. From May 2006 through September 2007, imagery from multiple cameras deployed around the volcano allowed determination of 3-dimensional motion across the dome complex. Analysis of the multi-camera imagery shows spatially differential, but remarkably steady to gradually slowing, motion, from about 1–2 m/d from May through October 2006, to about 0.2–1.0 m/d from May through September 2007. In contrast to the fluctuations in lineal extrusion rate documented during the first year of eruption, dome motion from May 2006 through September 2007 was monotonic (± 0.10 m/d) to gradually slowing on time scales of weeks to months. The ability to measure spatial and temporal rates of motion of the effusing lava dome from oblique terrestrial photographs provided a significant, and sometimes the sole, means of identifying and quantifying dome growth during the eruption, and it demonstrates the utility of using frequent, long-term terrestrial photography to monitor and study volcanic eruptions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  11. Initiation of Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2007-01-01

    We consider processes occurring just prior to and at the start of the onset of flare- and CME-producing solar eruptions. Our recent work uses observations of filament motions around the time of eruption onset as a proxy for the evolution of the fields involved in the eruption. Frequently the filaments show a slow rise prior to fast eruption, indicative of a slow expansion of the field that is about co explode. Work by us and others suggests that reconnection involving emerging or canceling flux results in a lengthening of fields restraining the filament-carrying field, and the consequent upward expansion of the field in and around the filament produces the filament's slow rise: that is, the reconnection weakens the magnetic "tethers" ("tether-weakening" reconnection), and results in the slow rise of the filament. It is still inconclusive, however, what mechanism is responsible for the switch from the slow rise to the fast eruption.

  12. Eruptive parameters and dynamics of the April 2015 sub-Plinian eruptions of Calbuco volcano (southern Chile)

    NASA Astrophysics Data System (ADS)

    Castruccio, Angelo; Clavero, Jorge; Segura, Andrea; Samaniego, Pablo; Roche, Olivier; Le Pennec, Jean-Luc; Droguett, Bárbara

    2016-09-01

    We conducted geological and petrological analyses of the tephra fallout and pyroclastic density current (PDC) products of the 22-23 April 2015 Calbuco eruptions. The eruptive cycle consisted of two sub-Plinian phases that generated > 15 km height columns and PDCs that travelled up to 6 km from the vent. The erupted volume is estimated at 0.38 km3 (non-DRE), with approximately 90% corresponding to tephra fall deposits and the other 10% to PDC deposits. The erupted products are basaltic-andesite, 54-55 wt.% SiO2, with minor amounts of andesite (58 wt.% SiO2). Despite the uniform composition of the products, there are at least four types of textures in juvenile clasts, with different degrees of vesicularity and types and content of crystals. We propose that the eruption triggering mechanism was either exsolution of volatiles due to crystallization, or a small intrusion into the base of the magma chamber, without significant magma mixing or with a magma compositionally similar to that of the residing magma. In either case the triggering mechanism generated convection and sufficient overpressure to promote the first eruptive phase. The start of the eruption decompressed the chamber, promoting intense vesiculation of the remaining magma and an increase in eruption rate towards the end of the eruption.

  13. Eruptive Source Parameters from Near-Source Gravity Waves Induced by Large Vulcanian eruptions

    NASA Astrophysics Data System (ADS)

    Barfucci, Giulia; Ripepe, Maurizio; De Angelis, Silvio; Lacanna, Giorgio; Marchetti, Emanuele

    2016-04-01

    The sudden ejection of hot material from volcanic vent perturbs the atmosphere generating a broad spectrum of pressure oscillations from acoustic infrasound (<10 Hz) to gravity waves (<0.03 Hz). However observations of gravity waves excited by volcanic eruptions are still rare, mostly limited to large sub-plinian eruptions and frequently at large distance from the source (>100 km). Atmospheric Gravity waves are induced by perturbations of the hydrostatic equilibrium of the atmosphere and propagate within a medium with internal density stratification. They are initiated by mechanisms that cause the atmosphere to be displaced as for the injection of volcanic ash plume during an eruption. We use gravity waves to infer eruptive source parameters, such as mass eruption rate (MER) and duration of the eruption, which may be used as inputs in the volcanic ash transport and dispersion models. We present the analysis of near-field observations (<7 km) of atmospheric gravity waves, with frequencies of 0.97 and 1.15 mHz, recorded by a pressure sensors network during two explosions in July and December 2008 at Soufrière Hills Volcano, Montserrat. We show that gravity waves at Soufrière Hills Volcano originate above the volcanic dome and propagate with an apparent horizontal velocities of 8-10 m/s. Assuming a single mass injection point source model, we constrain the source location at ~3.5 km a.s.l., above the vent, duration of the gas thrust < 140 s and MERs of 2.6 and 5.4 x10E7 kg/s, for the two eruptive events. Source duration and MER derived by modeling Gravity Waves are fully compatible with others independent estimates from field observations. Our work strongly supports the use of gravity waves to model eruption source parameters and can have a strong impact on our ability to monitor volcanic eruption at a large distance and may have future application in assessing the relative magnitude of volcanic explosions.

  14. Changes in Aerosol Chemistry in the Plume of Kilauea Volcano Caused by the 2008 Summit Eruption

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, E.; Oppenheimer, C.

    2009-05-01

    In March 2008 an eruption began in Halema'uma'u summit crater of Kilauea volcano; this was the first summit eruption since 1982. Prior to the new active phase, degassing in the crater was predominantly from several small fumaroles emitting a weak translucent plume. The 2003-2007 average SO2 emission rate was 140 tonnes per day and increased drastically to over 2000 tonnes per day in March 2008. The plume emitted from the crater during the eruption was concentrated and opaque, containing both ash and aerosol particles. Aerosol particles were sampled in the plume from Halema'uma'u before the start of the new eruptive phase (August 2007) and during it (May 2008). Particles emitted from Pu'u'O'o crater were collected at the rim and 8- 10km downwind. Sampling was done with a cascade impactor which collects and segregates PM10 (particle matter <10 μm) into 14 size fractions. There is a significant increase in PM sulphate concentration during the eruptive phase, or from 0.11 up to 6.3 μg per m3 of sampled air. Cl- concentration increased from 0.097 to 0.338 μgm-3, while F- was not detected either before or during the eruption. The SO42-/Cl- ratio increased from 0.15 to 18.8. The concentration peak of SO42- shifts to a coarser PM size fraction during the active phase, or from 0.18-0.32 to 0.32-0.56 μm. It is possible that higher water vapour content during the eruption favours more rapid particle growth. PM collected at Pu'u'O'o rim shows a noteworthy bimodal SO42- concentration distribution with a finer peak between 0.32-0.56 μm and a coarser peak between 1.0-1.4 μm. The coarser PM is efficiently removed from the plume and is not detected when sampled 8km downwind of the source. Near-vent nitrate was not detected in pre-eruptive samples but was found in concentrations between 0.17-0.58 μgm-3 in syn-eruptive PM; these are much lower than the concentrations seen at Pu'u'O'o (up to 3.0 μgm-3). Work in progress is analysis of metal content in the pre- and syn-eruptive

  15. Chronology of the 2015 eruption of Hakone volcano, Japan: geological background, mechanism of volcanic unrest and disaster mitigation measures during the crisis

    NASA Astrophysics Data System (ADS)

    Mannen, Kazutaka; Yukutake, Yohei; Kikugawa, George; Harada, Masatake; Itadera, Kazuhiro; Takenaka, Jun

    2018-04-01

    The 2015 eruption of Hakone volcano was a very small phreatic eruption, with total erupted ash estimated to be in the order of only 102 m3 and ballistic blocks reaching less than 30 m from the vent. Precursors, however, had been recognized at least 2 months before the eruption and mitigation measures were taken by the local governments well in advance. In this paper, the course of precursors, the eruption and the post-eruptive volcanic activity are reviewed, and a preliminary model for the magma-hydrothermal process that caused the unrest and eruption is proposed. Also, mitigation measures taken during the unrest and eruption are summarized and discussed. The first precursors observed were an inflation of the deep source and deep low-frequency earthquakes in early April 2015; an earthquake swarm then started in late April. On May 3, steam wells in Owakudani, the largest fumarolic area on the volcano, started to blowout. Seismicity reached its maximum in mid-May and gradually decreased; however, at 7:32 local time on June 29, a shallow open crack was formed just beneath Owakudani as inferred from sudden tilt change and InSAR analysis. The same day mud flows and/or debris flows likely started before 11:00 and ash emission began at about 12:30. The volcanic unrest and the eruption of 2015 can be interpreted as a pressure increase in the hydrothermal system, which was triggered by magma replenishment to a deep magma chamber. Such a pressure increase was also inferred from the 2001 unrest and other minor unrests of Hakone volcano during the twenty-first century. In fact, monitoring of repeated periods of unrest enabled alerting prior to the 2015 eruption. However, since open crack formation seems to occur haphazardly, eruption prediction remains impossible and evacuation in the early phase of volcanic unrest is the only way to mitigate volcanic hazard.[Figure not available: see fulltext.

  16. 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

  17. Thermodynamics of gas and steam-blast eruptions

    USGS Publications Warehouse

    Mastin, L.G.

    1995-01-01

    Eruptions of gas or steam and non-juvenile debris are common in volcanic and hydrothermal areas. From reports of non-juvenile eruptions or eruptive sequences world-wide, at least three types (or end-members) can be identified: (1) those involving rock and liquid water initially at boiling-point temperatures ('boiling-point eruptions'); (2) those powered by gas (primarily water vapor) at initial temperatures approaching magmatic ('gas eruptions'); and (3) those caused by rapid mixing of hot rock and ground- or surface water ('mixing eruptions'). For these eruption types, the mechanical energy released, final temperatures, liquid water contents and maximum theoretical velocities are compared by assuming that the erupting mixtures of rock and fluid thermally equilibrate, then decompress isentropically from initial, near-surface pressure (???10 MPa) to atmospheric pressure. Maximum mechanical energy release is by far greatest for gas eruptions (??????1.3 MJ/kg of fluid-rock mixture)-about one-half that of an equivalent mass of gunpowder and one-fourth that of TNT. It is somewhat less for mixing eruptions (??????0.4 MJ/kg), and least for boiling-point eruptions (??????0.25 MJ/kg). The final water contents of crupted boiling-point mixtures are usually high, producing wet, sloppy deposits. Final erupted mixtures from gas eruptions are nearly always dry, whereas those from mixing eruptions vary from wet to dry. If all the enthalpy released in the eruptions were converted to kinetic energy, the final velocity (vmax) of these mixtures could range up to 670 m/s for boiling-point eruptions and 1820 m/s for gas eruptions (highest for high initial pressure and mass fractions of rock (mr) near zero). For mixing eruptions, vmax ranges up to 1150 m/s. All observed eruption velocities are less than 400 m/s, largely because (1) most solid material is expelled when mr is high, hence vmax is low; (2) observations are made of large blocks the velocities of which may be less than the

  18. Prediction of Solar Eruptions Using Filament Metadata

    NASA Astrophysics Data System (ADS)

    Aggarwal, Ashna; Schanche, Nicole; Reeves, Katharine K.; Kempton, Dustin; Angryk, Rafal

    2018-05-01

    We perform a statistical analysis of erupting and non-erupting solar filaments to determine the properties related to the eruption potential. In order to perform this study, we correlate filament eruptions documented in the Heliophysics Event Knowledgebase (HEK) with HEK filaments that have been grouped together using a spatiotemporal tracking algorithm. The HEK provides metadata about each filament instance, including values for length, area, tilt, and chirality. We add additional metadata properties such as the distance from the nearest active region and the magnetic field decay index. We compare trends in the metadata from erupting and non-erupting filament tracks to discover which properties present signs of an eruption. We find that a change in filament length over time is the most important factor in discriminating between erupting and non-erupting filament tracks, with erupting tracks being more likely to have decreasing length. We attempt to find an ensemble of predictive filament metadata using a Random Forest Classifier approach, but find the probability of correctly predicting an eruption with the current metadata is only slightly better than chance.

  19. Early signs of geodynamic activity before the 2011-2012 El Hierro eruption

    NASA Astrophysics Data System (ADS)

    López, Carmen; García-Cañada, Laura; Martí, Joan; Domínguez Cerdeña, Itahiza

    2017-04-01

    The potential relation between mantle plume dynamics, regional tectonics and eruptive activity in the Canary Islands has not been studied yet through the analysis of long-time series of geophysical observational data. The existence of highly reliable seismic and GNSS data has enabled us to study from 1996 to 2014 the geodynamic evolution of the North Atlantic Azores-Gibraltar region and its relationship with recent volcanic activity in El Hierro (Canary Islands, Spain). We compiled a new and unified regional seismic catalog and used long time-series of surface displacements recorded by permanent GNSS stations in the region. A regional- and local-scale analysis based on these data enabled us to identify signs of anomalous tectonic activity from 2003 onwards, whose intensity increased in 2007 and finally accelerated three months before the onset of the volcanic eruption on El Hierro in October 2011. This activity includes a regional extension and an uplift process that affects the southern Iberian Peninsula, NW Africa, and the Canary Islands. We interpret these observations as early signs of the geodynamic activity, which led to El Hierro eruption and the subsequent episodes of magma intrusion. Results point to the significant contribution of the mantle plume dynamics (i.e. external forces) in this renewed volcanic activity in the Canary Islands and emphasize the role of mantle dynamics in controlling regional tectonics.

  20. Models of volcanic eruption hazards

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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 fluidmore » 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.« less

  1. Models of volcanic eruption hazards

    NASA Astrophysics Data System (ADS)

    Wohletz, K. H.

    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.

  2. Volcano geodesy: The search for magma reservoirs and the formation of eruptive vents

    USGS Publications Warehouse

    Dvorak, J.J.; Dzurisin, D.

    1997-01-01

    Routine geodetic measurements are made at only a few dozen of the world's 600 or so active volcanoes, even though these measurements have proven to be a reliable precursor of eruptions. The pattern and rate of surface displacement reveal the depth and rate of pressure increase within shallow magma reservoirs. This process has been demonstrated clearly at Kilauea and Mauna Loa, Hawaii; Long Valley caldera, California; Campi Flegrei caldera, Italy; Rabaul caldera, Papua New Guinea; and Aira caldera and nearby Sakurajima, Japan. Slower and lesser amounts of surface displacement at Yellowstone caldera, Wyoming, are attributed to changes in a hydrothermal system that overlies a crustal magma body. The vertical and horizontal dimensions of eruptive fissures, as well as the amount of widening, have been determined at Kilauea, Hawaii; Etna, Italy; Tolbachik, Kamchatka; Krafla, Iceland; and Asal-Ghoubbet, Djibouti, the last a segment of the East Africa Rift Zone. Continuously recording instruments, such as tiltmeters, extensometers, and dilatometers, have recorded horizontal and upward growth of eruptive fissures, which grew at rates of hundreds of meters per hour, at Kilauea; Izu-Oshima, Japan; Teishi Knoll seamount, Japan; and Piton de la Fournaise, Re??union Island. In addition, such instruments have recorded the hour or less of slight ground movement that preceded small explosive eruptions at Sakurajima and presumed sudden gas emissions at Galeras, Colombia. The use of satellite geodesy, in particular the Global Positioning System, offers the possibility of revealing changes in surface strain both local to a volcano and over a broad region that includes the volcano.

  3. Selected time-lapse movies of the east rift zone eruption of KĪlauea Volcano, 2004–2008

    USGS Publications Warehouse

    Orr, Tim R.

    2011-01-01

    Since 2004, the U.S. Geological Survey's Hawaiian Volcano Observatory has used mass-market digital time-lapse cameras and network-enabled Webcams for visual monitoring and research. The 26 time-lapse movies in this report were selected from the vast collection of images acquired by these camera systems during 2004–2008. Chosen for their content and broad aesthetic appeal, these image sequences document a variety of flow-field and vent processes from Kīlauea's east rift zone eruption, which began in 1983 and is still (as of 2011) ongoing.

  4. A cascade of magmatic events during the assembly and eruption of a super-sized magma body

    NASA Astrophysics Data System (ADS)

    Allan, Aidan. S. R.; Barker, Simon J.; Millet, Marc-Alban; Morgan, Daniel J.; Rooyakkers, Shane M.; Schipper, C. Ian; Wilson, Colin J. N.

    2017-07-01

    We use comprehensive geochemical and petrological records from whole-rock samples, crystals, matrix glasses and melt inclusions to derive an integrated picture of the generation, accumulation and evacuation of 530 km3 of crystal-poor rhyolite in the 25.4 ka Oruanui supereruption (New Zealand). New data from plagioclase, orthopyroxene, amphibole, quartz, Fe-Ti oxides, matrix glasses, and plagioclase- and quartz-hosted melt inclusions, in samples spanning different phases of the eruption, are integrated with existing data to build a history of the magma system prior to and during eruption. A thermally and compositionally zoned, parental crystal-rich (mush) body was developed during two periods of intensive crystallisation, 70 and 10-15 kyr before the eruption. The mush top was quartz-bearing and as shallow as 3.5 km deep, and the roots quartz-free and extending to >10 km depth. Less than 600 year prior to the eruption, extraction of large volumes of 840 °C low-silica rhyolite melt with some crystal cargo (between 1 and 10%), began from this mush to form a melt-dominant (eruptible) body that eventually extended from 3.5 to 6 km depth. Crystals from all levels of the mush were entrained into the eruptible magma, as seen in mineral zonation and amphibole model pressures. Rapid translation of crystals from the mush to the eruptible magma is reflected in textural and compositional diversity in crystal cores and melt inclusion compositions, versus uniformity in the outermost rims. Prior to eruption the assembled eruptible magma body was not thermally or compositionally zoned and at temperatures of 790 °C, reflecting rapid cooling from the 840 °C low-silica rhyolite feedstock magma. A subordinate but significant volume (3-5 km3) of contrasting tholeiitic and calc-alkaline mafic material was co-erupted with the dominant rhyolite. These mafic clasts host crystals with compositions which demonstrate that there was some limited pre-eruptive physical interaction of mafic

  5. Mount Cameroon Eruptions, Related Hazards and Effects on the Ecosystem

    NASA Astrophysics Data System (ADS)

    Aloatem Tazifor, A. N.

    2016-02-01

    Mount Cameroon (MC) is the highest peak in West and Central Africa. It is the only active volcano along the 1600km, Cameroon volcanic line with NE-SW orientation. It has a height of about 4100m above sea level, is a typical example of a hazardous volcano in a densely populated area, often causing damage by lava flows. It shows layered mafic volcanic sequence thought to be related to near-continuous eruptions within the last century during which period it has erupted 8 times in 1909, 1922, 1925, 1954, 1959, 1982, 1999 and 2000. These volcanic activities are suggested to be contributing factor to the many small-scale shallow landslides within the last 20 years which have resulted in the loss of about 30 lives and significant damage to farmland and property. The relatively high carbon dioxide (CO2) content in MC Glass inclusions support the interpretation that the CO2 gas responsible for the 1984 Lakes Monoun and 1986 Nyos disasters is magmatic in origin, which killed 37 and over 1800 people respectively. Months before the latest 2000 eruption, MC was characterized by a seismic swarm recorded in 03/2000 by analogue seismic stations. The co-eruptive period from May 28th to June 19th, 2000 was characterized by sequences of earth quakes, swarms and volcanic tremor. The main shock had a magnitude 3.2 event and a modified Mercalli intensity of 3 to 4. The largest seismic event recorded had a magnitude of 4. An explosion on 5th June, 2000, injured many members of a surveillance team, and a helicopter crash on 10th June, 2000 killed both pilots. It also led to lava flow across the Limbe-Idenau highway, damage of forest and palm plantations in Bakingili, and the evacuation of the 600 inhabitants of Bakingili. Never the less MC has positive impacts on the environment such as increased soil fertility where agro-industrial plantations have taken advantage, and more touristic sites have developed. After the last eruption of 2000, a number of seismographs have been placed along

  6. Serreta 1998-2001 submarine volcanic eruption, offshore Terceira (Azores): Characterization of the vent and inferences about the eruptive dynamics

    NASA Astrophysics Data System (ADS)

    Casas, David; Pimentel, Adriano; Pacheco, José; Martorelli, Eleonora; Sposato, Andrea; Ercilla, Gemma; Alonso, Belen; Chiocci, Francesco

    2018-05-01

    High-resolution bathymetric data and seafloor sampling were used to characterize the most recent volcanic eruption in the Azores region, the 1998-2001 Serreta submarine eruption. The vent of the eruption is proposed to be an asymmetric topographic high, composed of two coalescing volcanic cones, underlying the location where lava balloons had been observed at the sea surface during the eruption. The volcanic products related to the 1998-2001 eruption are constrained to an area of 0.5 km2 around the proposed vent position. A submarine Strombolian-style eruption producing basaltic lava balloons, ash and coarse scoriaceous materials with limited lateral dispersion led to the buildup of the cones. The 1998-2001 Serreta eruption shares many similarities with other intermediate-depth lava balloon-forming eruptions (e.g., the 1891 eruption offshore Pantelleria and the 2011-2012 eruption south of El Hierro), revealing the particular conditions needed for the production of this unusual and scarcely documented volcanic product.

  7. Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions

    NASA Technical Reports Server (NTRS)

    1979-01-01

    This photo of an active volcanic eruption on Jupiter's satellite Io was taken 1 hour, 52 minutes after the accompanying picture, late in the evening of March 4, 1979, Pacific time. On the limb of the satellite can be seen one of at least four simultaneous volcanic eruptions -- the first such activity ever observed on another celestial body. Seen against the limb are plume-like structures rising more than 60 miles (100 kilometers) above the surface. Several eruptions have been identified with volcanic structures on the surface of Io, which have also been identified by Voyager 1's infrared instrument as being abnormally hot -- several hundred degrees warmer than surrounding terrain. The fact that several eruptions appear to be occurring at the same time suggests that Io has the most active surface in the solar system and that volcanism is going on there essentially continuously. Another characteristic of the observed volcanism is that it appears to be extremely explosive, with velocities more than 2,000 miles an hour (at least 1 kilometer per second). That is more violent than terrestrial volcanoes like Etna, Vesuvius or Krakatoa.

  8. Microfilament-Eruption Mechanism for Solar Spicules

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2017-01-01

    Recent studies indicate that solar coronal jets result from eruption of small-scale filaments, or "minifilaments" (Sterling et al. 2015, Nature, 523, 437; Panesar et al. ApJL, 832L, 7). In many aspects, these coronal jets appear to be small-scale versions of long-recognized large-scale solar eruptions that are often accompanied by eruption of a large-scale filament and that produce solar flares and coronal mass ejections (CMEs). In coronal jets, a jet-base bright point (JBP) that is often observed to accompany the jet and that sits on the magnetic neutral line from which the minifilament erupts, corresponds to the solar flare of larger-scale eruptions that occurs at the neutral line from which the large-scale filament erupts. Large-scale eruptions are relatively uncommon (approximately 1 per day) and occur with relatively large-scale erupting filaments (approximately 10 (sup 5) kilometers long). Coronal jets are more common (approximately 100s per day), but occur from erupting minifilaments of smaller size (approximately 10 (sup 4) kilometers long). It is known that solar spicules are much more frequent (many millions per day) than coronal jets. Just as coronal jets are small-scale versions of large-scale eruptions, here we suggest that solar spicules might in turn be small-scale versions of coronal jets; we postulate that the spicules are produced by eruptions of "microfilaments" of length comparable to the width of observed spicules (approximately 300 kilometers). A plot of the estimated number of the three respective phenomena (flares/CMEs, coronal jets, and spicules) occurring on the Sun at a given time, against the average sizes of erupting filaments, minifilaments, and the putative microfilaments, results in a size distribution that can be fitted with a power-law within the estimated uncertainties. The counterparts of the flares of large-scale eruptions and the JBPs of jets might be weak, pervasive, transient brightenings observed in Hinode/CaII images, and

  9. Mt. Spurr's 1992 eruptions

    USGS Publications Warehouse

    1993-01-01

    On 27 June, 1992, the Crater Peak vent on the south side of Mt. Spurr awoke from 39 years of dormancy and burst into sub-plinian eruption after 10 months of elevated seismicity. Two more eruptions followed in August and September. The volcano lies 125 km west of Anchorage, Alaska's largest city and an important international hub for air travel. The Alaska Volcano Observatory (AVO) was able to warn communities and the aviation industry well in advance of these eruptions.

  10. The May 2003 eruption of Anatahan volcano, Mariana Islands: Geochemical evolution of a silicic island-arc volcano

    USGS Publications Warehouse

    Wade, J.A.; Plank, T.; Stern, R.J.; Tollstrup, D.L.; Gill, J.B.; O'Leary, J. C.; Eiler, J.M.; Moore, R.B.; Woodhead, J.D.; Trusdell, F.; Fischer, T.P.; Hilton, David R.

    2005-01-01

    The first historical eruption of Anatahan volcano began on May 10, 2003. Samples of tephra from early in the eruption were analyzed for major and trace elements, and Sr, Nd, Pb, Hf, and O isotopic compositions. The compositions of these tephras are compared with those of prehistoric samples of basalt and andesite, also newly reported here. The May 2003 eruptives are medium-K andesites with 59-63 wt.% SiO2, and are otherwise homogeneous (varying less than 3% 2?? about the mean for 45 elements). Small, but systematic, chemical differences exist between dark (scoria) and light (pumice) fragments, which indicate fewer mafic and oxide phenocrysts in, and less degassing for, the pumice than scoria. The May 2003 magmas are nearly identical to other prehistoric eruptives from Anatahan. Nonetheless, Anatahan has erupted a wide range of compositions in the past, from basalt to dacite (49-66 wt.% SiO2). The large proportion of lavas with silicic compositions at Anatahan (> 59 wt.% SiO2) is unique within the active Mariana Islands, which otherwise erupt a narrow range of basalts and basaltic andesites. The silicic compositions raise the question of whether they formed via crystal fractionation or crustal assimilation. The lack of 87Sr/86Sr variation with silica content, the MORB-like ??18O, and the incompatible behavior of Zr rule out assimilation of old crust, altered crust, or zircon-saturated crustal melts, respectively. Instead, the constancy of isotopic and trace element ratios, and the systematic variations in REE patterns are consistent with evolution by crystal fractionation of similar parental magmas. Thus, Anatahan is a type example of an island-arc volcano that erupts comagmatic basalts to dacites, with no evidence for crustal assimilation. The parental magmas to Anatahan lie at the low 143Nd/144Nd, Ba/La, and Sm/La end of the spectrum of magmas erupted in the Marianas arc, consistent with 1-3 wt.% addition of subducted sediment to the mantle source, or roughly one

  11. Source models for the March 5-9, 2011 Kamoamoa fissure eruption, Kilauea Volcano, Hawai`i, constrained by InSAR and in-situ observations

    NASA Astrophysics Data System (ADS)

    Lundgren, P.; Poland, M. P.; Miklius, A.; Yun, S.; Fielding, E. J.; Liu, Z.; Tanaka, A.; Szeliga, W. M.; Hensley, S.

    2011-12-01

    On March 5, 2011, the Kamoamoa fissure eruption began along the east rift zone (ERZ) of Kilauea Volcano. It followed several months of pronounced inflation at Kilauea's summit and was the first dike intrusion into the ERZ since June 2007. The eruption began in the late afternoon of March 5, 2011 (Hawaii Standard Time; UTC-10:00 hrs) with rapid deflation beginning at Pu'u 'O'o crater along the ERZ and followed about 30 minutes later at the summit. Magma from both locations fed the intrusion and an eruption that included lava fountaining along a set of discontinuous eruptive fissures ~2 km in length located between Napau and Pu'u 'O'o craters. Eruptive activity jumped between fissure segments until it ended on the night of March 9. A rich InSAR data set exists for this eruption from the COSMO-SkyMed (CSK), TerraSAR-X (TSX), ALOS PALSAR, and UAVSAR sensors. CSK data acquired on March 7 and processed that same day provided the earliest, quasi-real-time SAR data for this event. By March 10, after the eruption had ended, we had three CSK acquisitions and one ALOS scene acquired and processed. At present we have the following satellite data (UTC dates): ALOS March 6, 9, 11; CSK March 7, 10, 11; TSX March 11; from a mixture of ascending and descending tracks. UAVSAR airborne SAR data were acquired in early May 2011. Preliminary UAVSAR results are encouraging and complete processing should provide high-resolution data from four viewing directions. SAR data were acquired on all days of the eruption but March 8, allowing us to examine the progression of the dike opening beneath the surface with excellent spatial and temporal resolution. We use a combination of unwrapped interferograms, azimuthal pixel offsets, and in-situ data from GPS and electronic tiltmeters to model dike opening and summit deflation. GPS data are from the Hawaiian Volcano Observatory (HVO) continuous GPS network augmented by campaign occupations closer to the eruption area. Continuous tilt measurements

  12. The Eggøyan eruption in 1732, Jan Mayen; an emerging ankaramitic surtseyjan type eruption

    NASA Astrophysics Data System (ADS)

    Gjerlxw, E.; Hoskuldsson, A.; Pedersen, R. B.; Thorseth, I. H.

    2011-12-01

    Jan Mayen is a volcanic island situated at 71°N and 8°W. The Island is build up of two main edifices, Sør Jan and Nord Jan (Beerenberg). Volcanic activity on the island is little known, and however at least 4 eruptions are documented at the island since early 18th century. An expedition to the island in summer 2011 reveals that first of these eruptions formed the tuffcone Eggøyan in 1732 AD. The Eggøyan tuffcone is situated at the north east foot of Beerenberg volcano, about 2.5 km from the coastline marked by Valberget. The tuffcone is about 1.5 km in diameter and emerges from about 35 m depth to reach the altitude of at least 217 m above sea level. Pre Eggøyan Lava flows on the sandy coast west of the edifice are covered by up to 1.6 m of ash some 3 km from the vent. These lava flows have been suggested to be formed in the 1732 eruption and the 1818 eruption of Jan Mayen. However, they are covered with the Eggøyan tephra and thus considerable older. Volcanic tephra from the Eggøyan eruption forms the uppermost tephra layer on the Eastern flanks of Beerenberg. Contemporary description of the 1732 eruption, tell of violent explosive eruption at the east side of Beerenberg observed by German whalers for 28 hours, while sailing past the island in May that year. A Dutch wailer group arriving to the island in June that year, report fine ash covering the island in such a way they sink up to mid leg into it. Our study this summer shows that the only eruption these descriptions can report to are the Eggøyan eruption, dating it precisely to the spring 1732. The eruptive products are made up of frothy glass and ol, cpx and opx crystals, which characterize the flank eruptions of Beerenberg. In this presentation we shall present first results of intense fragmentation of deep gas rich ankaramitic magma from the Jan Mayen are and its interaction with seawater in shallow coastal settings.

  13. Recent eruptive history of Mount Hood, Oregon, and potential hazards from future eruptions

    USGS Publications Warehouse

    Crandell, Dwight Raymond

    1980-01-01

    Each of three major eruptive periods at Mount Hood (12,000-15,000(?), 1,500-1,800, and 200-300 years ago) produced dacite domes, pyroclastic flows, and mudflows, but virtually no pumice. Most of the fine lithic ash that mantles the slopes of the volcano and the adjacent mountains fell from ash clouds that accompanied the pyroclastic flows. Widely scattered pumice lapilli that are present at the ground surface on the south, east, and north sides of Mount Hood may have been erupted during the mid-1800's, when the last known activity of the volcano occurred. The geologically recent history of Mount Hood suggests that the most likely eruptive event in the future will be the formation of another dome, probably within the present south-facing crater. The principal hazards that could accompany dome formation include pyroclastic flows and mudflows moving from the upper slopes of the volcano down the floors of valleys. Ash clouds which accompany pyroclastic flows may deposit as much as a meter of fine ash close to their source, and as much as 20 centimeters at a distance of 11 kilometers downwind from the pyroclastic flows. Other hazards that could result from such eruptions include laterally directed explosive blasts that could propel rock fragments outward from the sides of a dome at high speed, and toxic volcanic gases. The scarcity of pumiceous ash erupted during the last 15,000 years suggests that explosive pumice eruptions are not a major hazard at Mount Hood; thus, there seems to be little danger that such an eruption will significantly affect the Portland (Oregon) metropolitan area in the near future.

  14. Merapi 2010 eruption—Chronology and extrusion rates monitored with satellite radar and used in eruption forecasting

    USGS Publications Warehouse

    Pallister, John S.; Schneider, David; Griswold, Julia P.; Keeler, Ronald H.; Burton, William C.; Noyles, Christopher; Newhall, Christopher G.; Ratdomopurbo, Antonius

    2013-01-01

    Despite dense cloud cover, satellite-borne commercial Synthetic Aperture Radar (SAR) enabled frequent monitoring of Merapi volcano's 2010 eruption. Near-real-time interpretation of images derived from the amplitude of the SAR signals and timely delivery of these interpretations to those responsible for warnings, allowed satellite remote sensing for the first time to play an equal role with in situ seismic, geodetic and gas monitoring in guiding life-saving decisions during a major volcanic crisis. Our remotely sensed data provide an observational chronology for the main phase of the 2010 eruption, which lasted 12 days (26 October–7 November, 2010). Unlike the prolonged low-rate and relatively low explosivity dome-forming and collapse eruptions of recent decades at Merapi, the eruption began with an explosive eruption that produced a new summit crater on 26 October and was accompanied by an ash column and pyroclastic flows that extended 8 km down the flanks. This initial explosive event was followed by smaller explosive eruptions on 29 October–1 November, then by a period of rapid dome growth on 1–4 November, which produced a summit lava dome with a volume of ~ 5 × 106 m3. A paroxysmal VEI 4 magmatic eruption (with ash column to 17 km altitude) destroyed this dome, greatly enlarged the new summit crater and produced extensive pyroclastic flows (to ~ 16 km radial distance in the Gendol drainage) and surges during the night of 4–5 November. The paroxysmal eruption was followed by a period of jetting of gas and tephra and by a second short period (12 h) of rapid dome growth on 6 November. The eruption ended with low-level ash and steam emissions that buried the 6 November dome with tephra and continued at low levels until seismicity decreased to background levels by about 23 November. Our near-real-time commercial SAR documented the explosive events on 26 October and 4–5 November and high rates of dome growth (> 25 m3 s− 1). An event tree

  15. Homologous prominence non-radial eruptions: A case study

    NASA Astrophysics Data System (ADS)

    Duchlev, P.; Koleva, K.; Madjarska, M. S.; Dechev, M.

    2016-10-01

    The present study provides important details on homologous eruptions of a solar prominence that occurred in active region NOAA 10904 on 2006 August 22. We report on the pre-eruptive phase of the homologous feature as well as the kinematics and the morphology of a forth from a series of prominence eruptions that is critical in defining the nature of the previous consecutive eruptions. The evolution of the overlying coronal field during homologous eruptions is discussed and a new observational criterion for homologous eruptions is provided. We find a distinctive sequence of three activation periods each of them containing pre-eruptive precursors such as a brightening and enlarging of the prominence body followed by small surge-like ejections from its southern end observed in the radio 17 GHz. We analyse a fourth eruption that clearly indicates a full reformation of the prominence after the third eruption. The fourth eruption although occurring 11 h later has an identical morphology, the same angle of propagation with respect to the radial direction, as well as similar kinematic evolution as the previous three eruptions. We find an important feature of the homologous eruptive prominence sequence that is the maximum height increase of each consecutive eruption. The present analysis establishes that all four eruptions observed in Hα are of confined type with the third eruption undergoing a thermal disappearance during its eruptive phase. We suggest that the observation of the same direction of the magnetic flux rope (MFR) ejections can be consider as an additional observational criterion for MFR homology. This observational indication for homologous eruptions is important, especially in the case of events of typical or poorly distinguishable morphology of eruptive solar phenomena.

  16. Regional Effects of the Mount Pinatubo Eruption on the Middle East and the Red Sea

    NASA Astrophysics Data System (ADS)

    Osipov, Sergey; Stenchikov, Georgiy

    2017-11-01

    The 1991 eruption of Mount Pinatubo had dramatic effects on the regional climate in the Middle East. Though acknowledged, these effects have not been thoroughly studied. To fill this gap and to advance understanding of the mechanisms that control variability in the Middle East's regional climate, we simulated the impact of the 1991 Pinatubo eruption using a regional coupled ocean-atmosphere modeling system set for the Middle East and North Africa (MENA) domain. We used the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) framework, which couples the Weather Research and Forecasting Model (WRF) model with the Regional Oceanic Modeling System (ROMS). We modified the WRF model to account for the radiative effect of volcanic aerosols. Our coupled ocean-atmosphere simulations verified by available observations revealed strong perturbations in the energy balance of the Red Sea, which drove thermal and circulation responses. Our modeling approach allowed us to separate changes in the atmospheric circulation caused by the impact of the volcano from direct regional radiative cooling from volcanic aerosols. The atmospheric circulation effect was significantly stronger than the direct volcanic aerosols effect. We found that the Red Sea response to the Pinatubo eruption was stronger and qualitatively different from that of the global ocean system. Our results suggest that major volcanic eruptions significantly affect the climate in the Middle East and the Red Sea and should be carefully taken into account in assessments of long-term climate variability and warming trends in MENA and the Red Sea.

  17. Pre-eruptive storage conditions of the Holocene dacite erupted from Kizimen Volcano, Kamchatka

    USGS Publications Warehouse

    Browne, B.; Izbekov, P.; Eichelberger, J.; Churikova, T.

    2010-01-01

    This study describes an investigation of the pre-eruptive conditions (T, P and fO2) of dacite magma erupted during the KZI cycle (12,000-8400 years ago) of Kizimen Volcano, Kamchatka, the earliest, most voluminous and most explosive eruption cycle in the Kizimen record. Hydrothermal, water-saturated experiments on KZI dacite pumice coupled with titanomagnetite-ilmenite geothermometry calculations require that the KZI dacite existed at a temperature of 823 ?? 20??C and pressures of 125-150 MPa immediately prior to eruption. This estimate corresponds to a lithologic contact between Miocene volcaniclastic rocks and Pliocene-Pleistocene volcanic rocks located at a depth of 5-6 km beneath the Kizimen edifice, which may have facilitated the accumulation of atypically large volumes of gas-rich dacite during the KZI cycle.

  18. INVESTIGATING TWO SUCCESSIVE FLUX ROPE ERUPTIONS IN A SOLAR ACTIVE REGION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheng, X.; Zhang, J.; Ding, M. D.

    2013-06-01

    We investigate two successive flux rope (FR1 and FR2) eruptions resulting in two coronal mass ejections (CMEs) on 2012 January 23. Both flux ropes (FRs) appeared as an EUV channel structure in the images of high temperature passbands of the Atmospheric Imaging Assembly prior to the CME eruption. Through fitting their height evolution with a function consisting of linear and exponential components, we determine the onset time of the FR impulsive acceleration with high temporal accuracy for the first time. Using this onset time, we divide the evolution of the FRs in the low corona into two phases: a slowmore » rise phase and an impulsive acceleration phase. In the slow rise phase of FR1, the appearance of sporadic EUV and UV brightening and the strong shearing along the polarity inverse line indicates that the quasi-separatrix-layer reconnection likely initiates the slow rise. On the other hand, for FR2, we mainly contribute its slow rise to the FR1 eruption, which partially opened the overlying field and thus decreased the magnetic restriction. At the onset of the impulsive acceleration phase, FR1 (FR2) reaches the critical height of 84.4 ± 11.2 Mm (86.2 ± 13.0 Mm) where the decline of the overlying field with height is fast enough to trigger the torus instability. After a very short interval (∼2 minutes), the flare emission began to enhance. These results reveal the compound activity involving multiple magnetic FRs and further suggest that the ideal torus instability probably plays the essential role of initiating the impulsive acceleration of CMEs.« less

  19. 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.

  20. Volcanic eruptions on Io

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  1. New interpretation of the so-called Nubian strata in northeast Africa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Klitzsch, E.H.; Squyres, C.H.

    1988-08-01

    Stratigraphical interpretation of the so-called Nubian Sandstone of Egypt and northern Sudan have led to new ideas on the structural and paleogeographical development of northeast Africa. The strata formerly comprised under the term Nubian Sandstone include sediments from Cambrian to Paleocene age. Based on field work and paleontological investigations during the last 10 years, these strata can be subdivided into three major cycles, each characterizing a certain structural situation of northeast Africa. The first or Paleozoic cycle comprises strata of Cambrian to Early Carboniferous age. These strata were deposited during a period of generally northern dip of northeast Africa; continentalmore » sediments transported northward interfinger with marine strata resulting from southward transgressions. Sediments of the second cycle were deposited during and after Gondwana and northern continents collided, which caused updoming of large areas of Egypt and bordering areas to the west and east. As a result, most of Egypt became subject to erosion; transgressions remained near the present northern edge of the continent, and purely continental deposition took place in northern Sudan and bordering areas in Chad and Libya. The resulting strata are similar to the Karroo of East Africa. Strata of the third cycle were deposited after Pangea began to disintegrate. Northeast Africa now had a generally northern dip again, and consequently deposition was controlled - as during the first cycle - by northward drainage and southward transgressions. This last cycle began during Late Jurassic time.« less

  2. 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

  3. The origin of a coarse lithic breccia in the 34 ka caldera-forming Sounkyo eruption, Taisetsu volcano group, central Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Yasuda, Y.; Suzuki-Kamata, K.

    2018-05-01

    The 34 ka Sounkyo eruption produced 7.6 km3 of tephra ( 5 km3 DRE) as fallout, ignimbrite, and lithic breccia units, forming a small, 2-km-diameter summit caldera in the Taisetsu volcano group, Japan. The Sounkyo eruption products are made up of five eruptive units (SK-A to -E) in proximal regions, corresponding to the distal deposits, a 1- to 2-m-thick pumice fallout and the Px-type ignimbrite up to 220 m thick. The eruption began with a fallout phase, producing unstable low eruption columns during the earlier phase to form a <7-m-thick succession of well-stratified fallouts (SK-A1 and the lower part of the distal fallout). The eruption column reached up to 25 km high (subplinian to plinian) and became more stable at the late of the phase, producing a < 60-m-thick, pumice-dominated fallout (SK-A2 and the upper part of the distal fallout). The second phase, the climax of the Sounkyo eruption, produced a widespread, valley-filling ignimbrite in both proximal and distal regions (SK-B and the Px-type ignimbrite). At the end of the climactic phase, the waning of the eruption led to extensive failure of the walls of the shallow conduit, generating a dense, lithic-rich, low-mobile pyroclastic density current (PDC) to form a >27-m-thick, unstratified and ungraded, coarse lithic breccia (SK-C). The failure in turn choked the conduit, and then the eruption stopped. After a short eruptive hiatus, the eruption resumed with a short-lived fall phase, establishing an eruption column up to 16 km high and producing a <6-m-thick scoria fallout (SK-D). Finally, the eruption ended with the generation of PDCs by eruption column collapse to form a 5- to 15-m-thick ignimbrite in the proximal area (SK-E). Volume relationships between the caldera, ejected magma, and ejected lithic fragments suggest that the caldera was not essentially formed by caldera collapse but, instead, by vent widening as a consequence of explosive erosion and failure of the shallow conduit. The dominance of shallow

  4. The longevity of lava dome eruptions

    NASA Astrophysics Data System (ADS)

    Wolpert, Robert L.; Ogburn, Sarah E.; Calder, Eliza S.

    2016-02-01

    Understanding the duration of past, ongoing, and future volcanic eruptions is an important scientific goal and a key societal need. We present a new methodology for forecasting the duration of ongoing and future lava dome eruptions based on a database (DomeHaz) recently compiled by the authors. The database includes duration and composition for 177 such eruptions, with "eruption" defined as the period encompassing individual episodes of dome growth along with associated quiescent periods during which extrusion pauses but unrest continues. In a key finding, we show that probability distributions for dome eruption durations are both heavy tailed and composition dependent. We construct objective Bayesian statistical models featuring heavy-tailed Generalized Pareto distributions with composition-specific parameters to make forecasts about the durations of new and ongoing eruptions that depend on both eruption duration to date and composition. Our Bayesian predictive distributions reflect both uncertainty about model parameter values (epistemic uncertainty) and the natural variability of the geologic processes (aleatoric uncertainty). The results are illustrated by presenting likely trajectories for 14 dome-building eruptions ongoing in 2015. Full representation of the uncertainty is presented for two key eruptions, Soufriére Hills Volcano in Montserrat (10-139 years, median 35 years) and Sinabung, Indonesia (1-17 years, median 4 years). Uncertainties are high but, importantly, quantifiable. This work provides for the first time a quantitative and transferable method and rationale on which to base long-term planning decisions for lava dome-forming volcanoes, with wide potential use and transferability to forecasts of other types of eruptions and other adverse events across the geohazard spectrum.

  5. SOLAR ERUPTION AND LOCAL MAGNETIC PARAMETERS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Jeongwoo; Chae, Jongchul; Liu, Chang

    It is now a common practice to use local magnetic parameters such as magnetic decay index for explaining solar eruptions from active regions, but there can be an alternative view that the global properties of the source region should be counted as a more important factor. We discuss this issue based on Solar Dynamics Observatory observations of the three successive eruptions within 1.5 hr from the NOAA active region 11444 and the magnetic parameters calculated using the nonlinear force-free field model. Two violent eruptions occurred in the regions with relatively high magnetic twist number (0.5–1.5) and high decay index (0.9–1.1)more » at the nominal height of the filament (12″) and otherwise a mild eruption occurred, which supports the local-parameter paradigm. Our main point is that the time sequence of the eruptions did not go with these parameters. It is argued that an additional factor, in the form of stabilizing force, should operate to determine the onset of the first eruption and temporal behaviors of subsequent eruptions. As supporting evidence, we report that the heating and fast plasma flow continuing for a timescale of an hour was the direct cause for the first eruption and that the unidirectional propagation of the disturbance determined the timing of subsequent eruptions. Both of these factors are associated with the overall magnetic structure rather than local magnetic properties of the active region.« less

  6. 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.

  7. 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

  8. 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

  9. Structure and Dynamics of Quiescent Prominence Eruptions

    NASA Astrophysics Data System (ADS)

    Su, Y.; Lu, M.; van Ballegooijen, A.

    2012-05-01

    We present a survey on the fine structure and dynamics of quiescent prominence eruptions observed both on the disk and at the limb. We have identified 45 quiescent prominence eruptions by looking at the SDO (Solar Dynamics Observatory)/AIA (Atmospheric Imaging Assembly) daily movies from April to June in 2011. Among these events, there are 24 symmetric eruptions (coherent loop-like eruptions) and 21 asymmetric eruptions (one footpoint lifts off) as shown by AIA and STEREO/EUVI observations. Vertical filament threads are identified in 10 out of the 45 events, while horizontal threads are observed in almost all eruptions. We find 23 events with twisting/untwisting motions. For 14 selected limb events, we carry out a detailed study of the eruption dynamics using AIA observations at 304 Å. We find that the initial heights of these erupting prominences are located around 50-110 Mm above the limb. The eruptions start from a speed of less than 5 km/s, then increase to several tens km/s in the AIA field of view. The maximum speed of these events is 50 km/s. The acceleration plots show a positive acceleration in the range of 0 to 20 m/s2. No significant difference is identified in the dynamics of the symmetric and asymmetric eruptions.

  10. A MODEL FOR MAGNETICALLY COUPLED SYMPATHETIC ERUPTIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Toeroek, T.; Titov, V. S.; Mikic, Z.

    2011-10-01

    Sympathetic eruptions on the Sun have been observed for several decades, but the mechanisms by which one eruption can trigger another remain poorly understood. We present a three-dimensional MHD simulation that suggests two possible magnetic trigger mechanisms for sympathetic eruptions. We consider a configuration that contains two coronal flux ropes located within a pseudo-streamer and one rope located next to it. A sequence of eruptions is initiated by triggering the eruption of the flux rope next to the streamer. The expansion of the rope leads to two consecutive reconnection events, each of which triggers the eruption of a flux ropemore » by removing a sufficient amount of overlying flux. The simulation qualitatively reproduces important aspects of the global sympathetic event on 2010 August 1 and provides a scenario for the so-called twin filament eruptions. The suggested mechanisms are also applicable for sympathetic eruptions occurring in other magnetic configurations.« less

  11. CME Eruption Onset Observations from EIT and SXT

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.

    2004-01-01

    Why CMEs erupt is a major outstanding puzzle of solar physics. Signatures observable at the earliest stages of eruption onset may hold precious clues about the onset mechanism. We present observations in EUV from SOHO/EIT and in soft X-rays from Yohkoh/SXT of the re-eruption and eruption phases of CME expulsion, along with the eruption's magnetic setting found from SOHO/MDI magnetograms. Most of our events involve clearly-observable filament eruptions and multiple neutral lines, and we use the magnetic settings and motions of the filaments to help infer the geometry and behavior of the associated erupting magnetic fields. Pre-eruption and early-eruption signatures include a relatively slow filament rise prior to eruption, and intensity "dimmings" and brightenings, both in the immediate neighborhood of the "core" (location of greatest magnetic shear) of the erupting fields and at locations remote from the core. These signatures and their relative timings place observational constraints on eruption mechanisms; our recent work has focused on implications for the so-called "tether cutting" and "breakout" models, but the same observational constraints are applicable to any model.

  12. The variation of magma discharge during basaltic eruptions

    NASA Technical Reports Server (NTRS)

    Wadge, G.

    1981-01-01

    The rate at which basaltic magma is discharged during many eruptions varies substantially. An individual eruption has an eruption rate, which is the volumetric rate of discharge averaged over the whole or a major part of an eruption, and an effusion rate, which is the volumetric flux rate at any given time. In many cases, the effusion rate soon reaches a maximum after a short period of waxing flow (partly because of magmatic expansion); it then falls more slowly in the later parts of the eruption. The release of elastic strain energy from stored magma and the subvolcanic reservoir during eruption can give a waning flow of this type an exponential form. A comparison of the eruption rates of eruptions of Mauna Loa, Kilauea and Etna shows that for each volcano there is a trend of decreasing effusion rate with increasing duration of eruption. It is noted that this relationship is not predicted by a simple elastic model of magma release. Two other processes are invoked to explain the eruptive histories of these volcanoes: modification of the eruptive conduits and the continued supply of magma from depth during eruption.

  13. Early signs of geodynamic activity before the 2011-2012 El Hierro eruption

    NASA Astrophysics Data System (ADS)

    López, Carmen; García-Cañada, Laura; Martí, Joan; Domínguez Cerdeña, Itahiza

    2017-02-01

    The potential relation between mantle plume dynamics, regional tectonics and eruptive activity in the Canary Islands has not been studied yet through the analysis of long-time series of geophysical observational data. The existence of highly reliable seismic and geodetic data has enabled us to study from 1996 to 2014 the geodynamic evolution of the North Atlantic Azores-Gibraltar region (including the NW African margin) and its relationship with recent volcanic activity in El Hierro (Canary Islands). We compiled a new and unified regional seismic catalog and used long time-series of digital 3D surface displacements recorded by permanent GPS stations in the region. A joint regional- and local-scale analysis based on these data enabled us to identify signs of anomalous tectonic activity from 2003 onwards, whose intensity increased in 2007 and finally accelerated three months before the onset of the volcanic eruption on El Hierro in October 2011. Activity included the occurrence of regional extension and an uplift process affecting the southern Iberian Peninsula, NW Africa, and the Canary Islands. We interpret these observations as early signs of the geodynamic activity, which led to El Hierro eruption and the subsequent episodes of magma intrusion. Results point to the significant contribution of the mantle plume dynamics (i.e. external forces) in this renewed volcanic activity in the Canary Islands and emphasize the role of mantle dynamics in controlling regional tectonics.

  14. SYMPATHETIC FILAMENT ERUPTIONS CONNECTED BY CORONAL DIMMINGS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jiang Yunchun; Yang Jiayan; Hong Junchao

    2011-09-10

    We present for the first time detailed observations of three successive, interdependent filament eruptions that occurred one by one within 5 hr from different locations beyond the range of a single active region. The first eruption was observed from an active region and was associated with a coronal mass ejection (CME), during which diffuse and complex coronal dimmings formed, largely extending to the two other filaments located in quiet-Sun regions. Then, both quiescent filaments consecutively underwent the second and third eruptions, while the nearby dimmings were persistent. Comparing the result of a derived coronal magnetic configuration, the magnetic connectivity betweenmore » the dimmings suggested that they were caused by the joint effect of simple expansion of overlying loop systems forced by the first eruption, as well as by its erupting field interacting or reconnecting with the surrounding magnetic structures. Note that the dimming process in the first eruption indicated a weakening and partial removal of an overlying magnetic field constraint on the two other filaments, and thus one can physically connect these eruptions as sympathetic. It appears that the peculiar magnetic field configuration in our event was largely favorable to the occurrence of sympathetic filament eruptions. Because coronal dimmings are frequent and common phenomena in solar eruptions, especially in CME events, it is very likely that they represent a universal agent that can link consecutive eruptions nearby with sympathetic eruptions.« less

  15. 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.

  16. Ozone depletion following future volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Eric Klobas, J.; Wilmouth, David M.; Weisenstein, Debra K.; Anderson, James G.; Salawitch, Ross J.

    2017-07-01

    While explosive volcanic eruptions cause ozone loss in the current atmosphere due to an enhancement in the availability of reactive chlorine following the stratospheric injection of sulfur, future eruptions are expected to increase total column ozone as halogen loading approaches preindustrial levels. The timing of this shift in the impact of major volcanic eruptions on the thickness of the ozone layer is poorly known. Modeling four possible climate futures, we show that scenarios with the smallest increase in greenhouse gas concentrations lead to the greatest risk to ozone from heterogeneous chemical processing following future eruptions. We also show that the presence in the stratosphere of bromine from natural, very short-lived biogenic compounds is critically important for determining whether future eruptions will lead to ozone depletion. If volcanic eruptions inject hydrogen halides into the stratosphere, an effect not considered in current ozone assessments, potentially profound reductions in column ozone would result.

  17. The ten-year eruption of Kilauea Volcano

    USGS Publications Warehouse

    Clague, D.A.; Heliker, C.

    1992-01-01

    About 1 km3 of lava erupted during the first 0 years of the eruption. Lava flows have destroyed 181 houses and severed the coastal highway along the volcano's south flank, severely restricting transportation on this part of the island of Hawaii. the eruption consisted of many distinct episodes characterized by activity at different vents and by different eruptive styles. the following summarizes the first 10 years of the eruption, starting with the initial outbreak in 1983.

  18. Syn-eruptive CO2 Degassing of Submarine Lavas Flows: Constraints on Eruption Dynamics

    NASA Astrophysics Data System (ADS)

    Soule, S. A.; Boulahanis, B.; Fundis, A.; Clague, D. A.; Chadwick, B.

    2013-12-01

    At fast- and intermediate-spreading rate mid-ocean ridges, quenched lava samples are commonly supersaturated in CO2 with concentrations similar to the pressure/depth of shallow crustal melt lenses. This supersaturation is attributed to rapid ascent and decompression rates that exceed the kinetic rates of bubble nucleation and growth. During emplacement, CO2 supersaturated lavas experience nearly isothermal and isobaric conditions over a period of hours. A recent study has demonstrated systematic decreases in CO2 with increasing transport distance (i.e. time) along a single flow pathway within the 2005-06 eruption at the East Pacific Rise (~2500 m.b.s.l.). Based on analysis of vesicle population characteristics and complementary noble gas measurements, it is proposed that diffusion of CO2 into bubbles can be used as a basis to model the gas loss from the melt and thus place constraints on the dynamics of the eruption. We suggest that submarine lava flows represent a natural experiment in degassing that isolates conditions of low to moderate supersaturation and highlights timescales of diffusion and vesiculation processes that are relevant to shallow crustal and conduit processes in subaerial basaltic volcanic systems. Here we report a new suite of volatile concentration analyses and vesicle size distributions from the 2011 eruption of Axial Volcano along the Juan de Fuca Ridge (~1500 m.b.s.l.). The lava flows from this eruption are mapped by differencing of repeat high-resolution bathymetric surveys, so that the geologic context of the samples is known. In addition, in-situ instrument records record the onset of the eruption and place constraints on timing that can be used to verify estimates of eruption dynamics derived from degassing. This sample suite provides a comprehensive view of the variability in volatile concentrations within a submarine eruption and new constraints for evaluating models of degassing and vesiculation. Initial results show systematic

  19. 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.

  20. [Recognizing and preventing disturbances in eruption].

    PubMed

    van der Linden, F P G M

    2014-04-01

    Disturbances in eruption and related problems are quite common in permanent dentition but rare in deciduous dentition. For the timely recognition of disturbances in eruption, knowledge of the normal development of dentition is essential. Disturbances in eruption comprise disturbances in which eruption does not occur at all, in which it is delayed or incomplete, or in which the normal direction of eruption is influenced. If identified early enough, many undesirable dental conditions can be avoided or their seriousness can be limited. A possible impacting of permanent cuspids, for example, can be avoided by extracting the deciduous cuspids at the right moment; in cases of a large overjet or the threat of a cover-bite, lip interference can be prevented.

  1. Can tides influence volcanic eruptions?

    NASA Astrophysics Data System (ADS)

    Girona, T.; Huber, C.

    2015-12-01

    The possibility that the Moon-Sun gravitational force can affect terrestrial volcanoes and trigger eruptions is a controversial issue that has been proposed since ancient times, and that has been widely debated during the last century. The controversy arises mainly from two reasons. First, the days of initiation of eruptions are not well known for many volcanoes, and thus a robust statistical comparison with tidal cycles cannot be performed for many of them. Second, the stress changes induced by tides in the upper crust are very small (10-3 MPa) compared to the tensile strength of rocks (~ 10-1-10 MPa), and hence the mechanism by which tidal stresses might trigger eruptions is unclear. In this study, we address these issues for persistently degassing volcanoes, as they erupt frequently and thus the initiation time of a significant number of eruptions (>30) is well known in several cases (9). In particular, we find that the occurrence of eruptions within ±2 days from neap tides (first and third quarter moon) is lower than 34% (e.g., 29% for Etna, Italy; 28% for Merapi, Indonesia), which is the value expected if eruptions occur randomly with no external influence. To understand this preference for erupting far away from neap tides, we have developed a new lumped-parameter model that accounts for the deformation of magma reservoirs, a partially open conduit, and a gas layer where bubbles accumulate beneath volcanic craters before being released. We demonstrate that this system reservoir-conduit-gas layer acts as an amplifier of the tidal stresses, such that, when a volcano approaches to a critical state, the gas overpressure beneath the crater can reach up to several MPa more during a spring tide (full and new moon) than during a neap tide. This amplification mechanism can explain why active volcanoes are sensitive to the moon cycles.

  2. The Hekla eruption of 1845 - Volume and characteristics of the tephra layer.

    NASA Astrophysics Data System (ADS)

    Gudnason, Jonas; Thordarson, Thor; Houghton, Bruce

    2014-05-01

    The eruption of Hekla in 1845 started on the 2nd of September around 9 am, activity lasted until the 13-16th of August 1846 with minor activity in August the same year (Thorarinsson, 1968). Written accounts describe precursor earthquakes followed by a shadow casted over the Land district by the ~10-20km high eruption plume that drifted to the east-southeast and eruption induced flash floods in the river Rangá (Erlendsson, 1847). Contemporary description at sites some 80 km downwind indicate first sighting of the eruption plume at ~10 am and tephra falling on the ground at ~11 am. Around noon the tephra fall began to dissipate and was over by 3 pm. Reports of ash fall beyond the shores of Iceland are preserved in records from 3 ships of the southeast coast of Iceland as well as from the Faeroe and the Shetland Islands. The 1845 eruption is divided into three phases based on style of activity, phase 1 (the focus of this study) is the initial explosive phase that produced bulk of the tephra fall, phase 2, which is a transitional phase where explosive intensity of the eruption declines abruptly and shifts towards effusive activity, which is phase 3. The 1845 tephra layer is a marker layer in the soils of South Central Iceland, a well sorted homogeneous brownish tephra. Its distribution has been re-mapped via thicknesses and mass-per-area measurements at ~120 locations. In addition, grain size samples were collected at each measuring site. Our preliminary mapping results indicate that tephra fall on land was approximately 16000 km2, the thickness half distance is approximately 17 km with principal axis passing over Torfajökull and to Kirkjubæjarklaustur. In the proximal sector, straight east of Hekla, the maximum measured thickness of the tephra layer is 37 cm. Density analyzes of three 100 clast sets of juveniles range in mean from 560-690 kg/m3 and exhibit a tight unimodal and log-normal distribution with measured a mean vesicularity of 74% to 79% for the magma

  3. Microearthquake focal mechanisms and ring-fault mechanics during periods of inflation, deflation, and re-inflation surrounding the 2015 eruption of Axial Seamount

    NASA Astrophysics Data System (ADS)

    Levy, S. R.; Bohnenstiehl, D. R.; Weis, J.

    2016-12-01

    The Axial Seamount eruption during April and May of 2015 presents a unique opportunity to study volcanic processes along an oceanic spreading center. The recently installed Ocean Observatory Initiative Cabled Array provides continuous access to seismic and seafloor deformation data spanning the eruption. Composite focal mechanisms are created using at least east four nearby events with well-correlated waveforms. These event clusters are located along both the east and west sides of the caldera. The P- and S- wave first motions and S/P amplitude ratios are used to produce the focal solutions with the HASH program. During the period before the eruption, as the caldera floor is steadily inflating, focal mechanisms are consistent with normal slip along outward dipping ring faults. During the eruption period, the center of the caldera floor deflates by 2.5 m as a dike is emplaced along the volcano's northern rift zone. Focal mechanism solutions during this time suggest these ring faults are re-activated with a reverse sense of motion to accommodate this deflation. Re-inflation of the volcano began in late May of 2015 and continues. Seismicity rates following the eruption are low, and focal mechanisms during this time period show more complicated results, with both normal and reverse slip movement present. As the inflation cycle matures it is hypothesized that a more consistent pattern of normal slip will again be observed along these faults.

  4. The submarine volcano eruption at the island of El Hierro: physical-chemical perturbation and biological response

    NASA Astrophysics Data System (ADS)

    Fraile-Nuez, E.; Santana-Casiano, J.; Gonzalez-Davila, M.

    2013-12-01

    On October 10 2011 an underwater eruption gave rise to a novel shallow submarine volcano south of the island of El Hierro, Canary Islands, Spain. During the eruption large quantities of mantle-derived gases, solutes and heat were released into the surrounding waters. In order to monitor the impact of the eruption on the marine ecosystem, periodic multidisciplinary cruises were carried out. Here, we present an initial report of the extreme physical-chemical perturbations caused by this event, comprising thermal changes, water acidification, deoxygenation and metal-enrichment, which resulted in significant alterations to the activity and composition of local plankton communities. Our findings highlight the potential role of this eruptive process as a natural ecosystem-scale experiment for the study of extreme effects of global change stressors on marine environments. (A) Natural color composite from the MEdium Resolution Imaging Spectrometer (MERIS) instrument aboard ENVISAT Satellite (European Space Agency), (November 9, 2011 at 14:45 UTC). Remote sensing data have been used to monitor the evolution of the volcanic emissions, playing a fundamental role during field cruises in guiding the Spanish government oceanographic vessel to the appropriate sampling areas. The inset map shows the position of Canary Islands west of Africa and the study area (solid white box). (B) Location of the stations carried out from November 2011 to February 2012 at El Hierro. Black lines denote transects A-B and C-D.

  5. El Cobreloa: A geyser with two distinct eruption styles

    NASA Astrophysics Data System (ADS)

    Namiki, Atsuko; Muñoz-Saez, Carolina; Manga, Michael

    2014-08-01

    We performed field measurements at a geyser nicknamed "El Cobreloa," located in the El Tatio Geyser Field, Northern Andes, Chile. The El Cobreloa geyser has two distinct eruption styles: minor eruptions and more energetic and long-lived major eruptions. Minor eruptions splash hot water intermittently over an approximately 4 min time period. Major eruptions begin with an eruption style similar to minor eruptions, but then transition to a voluminous liquid water-dominated eruption, and finally end with energetic steam discharge that continues for approximately 1 h. We calculated eruption intervals by visual observations, acoustic measurements, and ground temperature measurements and found that each eruption style has a regular interval: 4 h and 40 min for major eruptions and ˜14 min for minor eruptions. Eruptions of El Cobreloa and geochemical measurements suggest interaction of three water sources. The geyser reservoir, connected to the surface by a conduit, is recharged by a deep, hot aquifer. More deeply derived magmatic fluids heat the reservoir. Boiling in the reservoir releases steam and hot liquid water to the overlying conduit, causing minor eruptions, and heating the water in the conduit. Eventually the water in the conduit becomes warm enough to boil, leading to a steam-dominated eruption that empties the conduit. The conduit is then recharged by a shallow, colder aquifer, and the eruption cycle begins anew. We develop a model for minor eruptions which heat the water in the conduit. El Cobreloa provides insight into how small eruptions prepare the geyser system for large eruptions.

  6. The 2013 Eruptions of Pavlof and Mount Veniaminof Volcanoes, Alaska

    NASA Astrophysics Data System (ADS)

    Schneider, D. J.; Waythomas, C. F.; Wallace, K.; Haney, M. M.; Fee, D.; Pavolonis, M. J.; Read, C.

    2013-12-01

    Pavlof Volcano and Mount Veniaminof on the Alaska Peninsula erupted during the summer of 2013 and were monitored by the Alaska Volcano Observatory (AVO) using seismic data, satellite and web camera images, a regional infrasound array and observer reports. An overview of the work of the entire AVO staff is presented here. The 2013 eruption of Pavlof Volcano began on May 13 after a brief and subtle period of precursory seismicity. Two volcano-tectonic (VT) earthquakes at depths of 6-8 km on April 24 preceded the onset of the eruption by 3 weeks. Given the low background seismicity at Pavlof, the VTs were likely linked to the ascent of magma. The onset of the eruption was marked by subtle pulsating tremor that coincided with elevated surface temperatures in satellite images. Activity during May and June was characterized by lava fountaining and effusion from a vent near the summit. Seismicity consisted of fluctuating tremor and numerous explosions that were detected on an infrasound array (450 km NE) and as ground-coupled airwaves at local and distant seismic stations (up to 650 km). Emissions of ash and sulfur dioxide were observed in satellite data extending as far as 300 km downwind at altitudes of 5-7 km above sea level. Ash collected in Sand Point (90 km E) were well sorted, 60-150 micron diameter juvenile glass shards, many of which had fluidal forms. Automated objective ash cloud detection and cloud height retrievals from the NOAA volcanic cloud alerting system were used to evaluate the hazard to aviation. A brief reconnaissance of Pavlof in July found that lava flows on the NW flank consist of rubbly, clast rich, 'a'a flows composed of angular blocks of agglutinate and rheomorphic lava. There are at least three overlapping flows, the longest of which extends about 5 km from the vent. Eruptive activity continued through early July, and has since paused or stopped. Historical eruptions of Mount Veniaminof volcano have been from an intracaldera cone within a 10

  7. Regional Climate Modeling of Volcanic Eruptions and the Arctic Climate System: A Baffin Island Case Study

    NASA Astrophysics Data System (ADS)

    Losic, M.; Robock, A.

    2010-12-01

    It is well-understood that the effects of volcanic aerosol loading into the stratosphere are transient, with global cooling lasting only a few years after a single large eruption. Geological evidence collected from Northern Baffin Island, Canada, suggests ice cap growth began soon after a succession of several large eruptions in the 13th century, and they did not start to melt until roughly a century ago. We investigate which feedbacks allowed these ice caps to be maintained long after the transient forcing of the volcanic aerosols, by conducting sensitivity studies with the Weather Research and Forecasting (WRF) Model and Polar WRF, a version of WRF developed specifically for the polar regions. Results from an ensemble of month-long regional simulations over Baffin Island suggest that better treatment of snow and ice in Polar WRF improves our regional climate simulations. Thus, sensitivity test results from decade-long runs with imposed changes to boundary condition temperatures and carbon dioxide concentrations using Polar WRF are presented. Preliminary findings suggest that not only large scale but localized climate feedbacks play an important role in the responses of the ice caps after temperature and carbon dioxide forcings are applied. The results from these and further sensitivity tests will provide insight into the influence of regional feedbacks on the persistence of these ice caps long after the 13th century eruptions.

  8. Flux Cancellation Leading to CME Filament Eruptions

    NASA Technical Reports Server (NTRS)

    Popescu, Roxana M.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

    2016-01-01

    Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to approx.100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable, often by magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions. We find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two CME-producing eruptions in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field, and thereafter evolve in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

  9. 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

  10. Flux Cancelation: The Key to Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald; Chakrapani, Prithi; Innes, Davina; Schmit, Don; Tiwari, Sanjiv

    2017-01-01

    Solar coronal jets are magnetically channeled eruptions that occur in all types of solar environments (e.g. active regions, quiet-Sun regions and coronal holes). Recent studies show that coronal jets are driven by the eruption of small-scare filaments (minifilaments). Once the eruption is underway magnetic reconnection evidently makes the jet spire and the bright emission in the jet base. However, the triggering mechanism of these eruptions and the formation mechanism of the pre-jet minifilaments are still open questions. In this talk, mainly using SDOAIA and SDOHIM data, first I will address the question: what triggers the jet-driving minifilament eruptions in different solar environments (coronal holes, quiet regions, active regions)? Then I will talk about the magnetic field evolution that produces the pre-jet minifilaments. By examining pre-jet evolutionary changes in line-of-sight HMI magnetograms while examining concurrent EUV images of coronal and transition-region emission, we find clear evidence that flux cancelation is the main process that builds pre-jet minifilaments, and is also the main process that triggers the eruptions. I will also present results from our ongoing work indicating that jet-driving minifilament eruptions are analogous to larger-scare filament eruptions that make flares and CMEs. We find that persistent flux cancellation at the neutral line of large-scale filaments often triggers their eruptions. From our observations we infer that flux cancelation is the fundamental process from the buildup and triggering of solar eruptions of all sizes.

  11. Flux Cancelation: The Key to Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald; Chakrapani, Prithi; Innes, Davina; Schmit, Don; Tiwari, Sanjiv

    2017-01-01

    Solar coronal jets are magnetically channeled eruptions that occur in all types of solar environments (e.g. active regions, quiet-Sun regions and coronal holes). Recent studies show that coronal jets are driven by the eruption of small-scale filaments (minifilaments). Once the eruption is underway magnetic reconnection evidently makes the jet spire and the bright emission in the jet base. However, the triggering mechanism of these eruptions and the formation mechanism of the pre-jet minifilaments are still open questions. In this talk, mainly using SDO/AIA and SDO/HMI data, first I will address the question: what triggers the jet-driving minifilament eruptions in different solar environments (coronal holes, quiet regions, active regions)? Then I will talk about the magnetic field evolution that produces the pre-jet minifilaments. By examining pre-jet evolutionary changes in line-of-sight HMI magnetograms while examining concurrent EUV images of coronal and transition-region emission, we find clear evidence that flux cancellation is the main process that builds pre-jet minifilaments, and is also the main process that triggers the eruptions. I will also present results from our ongoing work indicating that jet-driving minifilament eruptions are analogous to larger-scale filament eruptions that make flares and CMEs. We find that persistent flux cancellation at the neutral line of large-scale filaments often triggers their eruptions. From our observations we infer that flux cancellation is the fundamental process for the buildup and triggering of solar eruptions of all sizes.

  12. Inherited retarded eruption in the permanent dentition.

    PubMed

    Rasmussen, P; Kotsaki, A

    1997-01-01

    The term retarded eruption, may be used in cases where eruption is inhibited, causing an interruption in the coordination of tooth formation and tooth eruption. The phenomenon may be local or general, and several etiological factors for retarded eruption have been listed, comprising a lack of space, ankylosis, cysts, supernumerary teeth, hormone and vitamin deficiencies and several developmental disturbances and syndromes. The present paper describes several cases of retarded eruption where no factors other than inheritance have been evident. So far 14 cases have been evaluated, 9 boys and 5 girls. In addition several cases have been registered among parents and grandparents of the probands. Typical features are: retarded eruption, defined as more than 3 SD beyond mean eruption figures, comprises all teeth in the permanent dentition, and in 5 cases also second primary molars. The chronology of tooth formation are within normal limits. Consequently the teeth finish development still laying deeply buried in the jaws, often in aberrant positions and with curves or hooks on the roots. When the teeth finally get the "signal" for eruption, 5-15 years beyond normal eruption time, they move rather quickly into right positions, despite the long eruption paths and the hooked roots. Permanent teeth without, as well as with predecessors, are affected. Extraction of predecessors does not seem to provoke eruption. The main features in management are to take care of the primary teeth, to improve-esthetics, and offer surgery and orthodontics when needed. Analyses of pedigrees indicates that the genetic transmittance may be autosomal dominant as both sexes are affected, about half of the siblings show the trait, and the trait shows continuity through generations.

  13. Cyclic flank-vent and central-vent eruption patterns

    NASA Astrophysics Data System (ADS)

    Takada, Akira

    Many basaltic and andesitic polygenetic volcanoes have cyclic eruptive activity that alternates between a phase dominated by flank eruptions and a phase dominated by eruptions from a central vent. This paper proposes the use of time-series diagrams of eruption sites on each polygenetic volcano and intrusion distances of dikes to evaluate volcano growth, to qualitatively reconstruct the stress history within the volcano, and to predict the next eruption site. In these diagrams the position of an eruption site is represented by the distance from the center of the volcano and the clockwise azimuth from north. Time-series diagrams of Mauna Loa, Kilauea, Kliuchevskoi, Etna, Sakurajima, Fuji, Izu-Oshima, and Hekla volcanoes indicate that fissure eruption sites of these volcanoes migrated toward the center of the volcano linearly, radially, or spirally with damped oscillation, occasionally forming a hierarchy in convergence-related features. At Krafla, terminations of dikes also migrated toward the center of the volcano with time. Eruption sites of Piton de la Fournaise did not converge but oscillated around the center. After the convergence of eruption sites with time, the central eruption phase is started. The intrusion sequence of dikes is modeled, applying crack interaction theory. Variation in convergence patterns is governed by the regional stress and the magma supply. Under the condition that a balance between regional extension and magma supply is maintained, the central vent convergence time during the flank eruption phase is 1-10 years, whereas the flank vent recurrence time during the central eruption phase is greater than 100 years owing to an inferred decrease in magma supply. Under the condition that magma supply prevails over regional extension, the central vent convergence time increases, whereas the flank vent recurrence time decreases owing to inferred stress relaxation. Earthquakes of M>=6 near a volcano during the flank eruption phase extend the

  14. Mt Agung (Bali) Eruption Plumes

    Atmospheric Science Data Center

    2018-05-23

    article title:  Mt Agung (Bali) Eruption Plumes     View larger image ... 2017 (left) and calculated plume heights (right)   Volcanic eruptions can generate a significant amount of atmospheric aerosols ...

  15. Eruptive and tectonic history of the Endeavour Segment, Juan de Fuca Ridge, based on AUV mapping data and lava flow ages

    USGS Publications Warehouse

    Clague, David A.; Dreyer, Brian M; Paduan, Jennifer B; Martin, Julie F; Caress, David W; Gillespie, James B.; Kelley, Deborah S; Thomas, Hans; Portner, Ryan A; Delaney, John R; Guilderson, Thomas P.; McGann, Mary L.

    2014-01-01

    High-resolution bathymetric surveys from autonomous underwater vehicles ABE and D. Allan B. were merged to create a coregistered map of 71.7 km2 of the Endeavour Segment of the Juan de Fuca Ridge. Radiocarbon dating of foraminifera in cores from three dives of remotely operated vehicle Doc Ricketts provide minimum eruption ages for 40 lava flows that are combined with the bathymetric data to outline the eruptive and tectonic history. The ages range from Modern to 10,700 marine-calibrated years before present (yr BP). During a robust magmatic phase from >10,700 yr BP to ~4300 yr BP, flows erupted from an axial high and many flowed >5 km down the flanks; some partly buried adjacent valleys. Axial magma chambers (AMCs) may have been wider than today to supply dike intrusions over a 2 km wide axial zone. Summit Seamount formed by ~4770 yr BP and was subsequently dismembered during a period of extension with little volcanism starting ~4300 yr BP. This tectonic phase with only rare volcanic eruptions lasted until ~2300 yr BP and may have resulted in near-solidification of the AMCs. The axial graben formed by crustal extension during this period of low magmatic activity. Infrequent eruptions occurred on the flanks between 2620–1760 yr BP and within the axial graben since ~1750 yr BP. This most recent phase of limited volcanic and intense hydrothermal activity that began ~2300 yr BP defines a hydrothermal phase of ridge development that coincides with the present-day 1 km wide AMCs and overlying hydrothermal vent fields.

  16. Topological Analyses of Symmetric Eruptive Prominences

    NASA Astrophysics Data System (ADS)

    Panasenco, O.; Martin, S. F.

    Erupting prominences (filaments) that we have analyzed from Hα Doppler data at Helio Research and from SOHO/EIT 304 Å, show strong coherency between their chirality, the direction of the vertical and lateral motions of the top of the prominences, and the directions of twisting of their legs. These coherent properties in erupting prominences occur in two patterns of opposite helicity; they constitute a form of dynamic chirality called the ``roll effect." Viewed from the positive network side as they erupt, many symmetrically-erupting dextral prominences develop rolling motion toward the observer along with right-hand helicity in the left leg and left-hand helicity in the right leg. Many symmetricaly-erupting sinistral prominences, also viewed from the positive network field side, have the opposite pattern: rolling motion at the top away from the observer, left-hand helical twist in the left leg, and right-hand twist in the right leg. We have analysed the motions seen in the famous movie of the ``Grand Daddy" erupting prominence and found that it has all the motions that define the roll effect. From our analyses of this and other symmetric erupting prominences, we show that the roll effect is an alternative to the popular hypothetical configuration of an eruptive prominence as a twisted flux rope or flux tube. Instead we find that a simple flat ribbon can be bent such that it reproduces nearly all of the observed forms. The flat ribbon is the most logical beginning topology because observed prominence spines already have this topology prior to eruption and an initial long magnetic ribbon with parallel, non-twisted threads, as a basic form, can be bent into many more and different geometrical forms than a flux rope.

  17. Identifying recycled ash in basaltic eruptions

    PubMed Central

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

    2014-01-01

    Deposits of mid-intensity basaltic explosive eruptions are characterized by the coexistence of different types of juvenile clasts, which show a large variability of external properties and texture, reflecting alternatively the effects of primary processes related to magma storage or ascent, or of syn-eruptive modifications occurred during or immediately after their ejection. If fragments fall back within the crater area before being re-ejected during the ensuing activity, they are subject to thermally- and chemically-induced alterations. These ‘recycled' clasts can be considered as cognate lithic for the eruption/explosion they derive. Their exact identification has consequences for a correct interpretation of eruption dynamics, with important implications for hazard assessment. On ash erupted during selected basaltic eruptions (at Stromboli, Etna, Vesuvius, Gaua-Vanuatu), we have identified a set of characteristics that can be associated with the occurrence of intra-crater recycling processes, based also on the comparison with results of reheating experiments performed on primary juvenile material, at variable temperature and under different redox conditions. PMID:25069064

  18. Reduced cooling following future volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Hopcroft, Peter O.; Kandlbauer, Jessy; Valdes, Paul J.; Sparks, R. Stephen J.

    2017-11-01

    Volcanic eruptions are an important influence on decadal to centennial climate variability. Large eruptions lead to the formation of a stratospheric sulphate aerosol layer which can cause short-term global cooling. This response is modulated by feedback processes in the earth system, but the influence from future warming has not been assessed before. Using earth system model simulations we find that the eruption-induced cooling is significantly weaker in the future state. This is predominantly due to an increase in planetary albedo caused by increased tropospheric aerosol loading with a contribution from associated changes in cloud properties. The increased albedo of the troposphere reduces the effective volcanic aerosol radiative forcing. Reduced sea-ice coverage and hence feedbacks also contribute over high-latitudes, and an enhanced winter warming signal emerges in the future eruption ensemble. These findings show that the eruption response is a complex function of the environmental conditions, which has implications for the role of eruptions in climate variability in the future and potentially in the past.

  19. Structure and Dynamics of Quiescent Prominence Eruptions

    NASA Astrophysics Data System (ADS)

    Lu, Muzhou; Su, Y.; Adriaan van Ballegooijen, A.

    2012-05-01

    We present a survey on the fine structure and dynamics of quiescent prominence eruptions observed both on the disk and at the limb. We have identified 45 quiescent prominence eruptions by looking at the SDO (Solar Dynamics Observatory)/AIA (Atmospheric Imaging Assembly) daily movies from April to June in 2011. Among these events, there are 24 symmetric eruptions (coherent loop-like eruptions) and 21 asymmetric eruptions (one footpoint lifts off) as shown by AIA and STEREO/EUVI observations. Vertical filament threads are identified in 10 out of the 45 events, while horizontal threads are observed in almost all eruptions. We find 23 events with twisting/untwisting motions. For 14 selected limb events, we carry out a detailed study of the eruption dynamics using AIA observations at 304 Å. We find that the initial heights of these erupting prominences are located around 50-110 Mm above the limb. The eruptions start from a speed of less than 5 km/s, then increase to several tens km/s in the AIA field of view. The maximum speed of these events is 50 km/s. The acceleration plots show a positive acceleration in the range of 0 to 20 m/s^2. No significant difference is identified in the dynamics of the symmetric and asymmetric eruptions. Acknowledgments. This project is supported by the NASA contract SP02H1701R from LMSAL to Smithsonian Astrophysical Observatory (SAO). M. Lu is supported under the NSF-REU solar physics program at SAO, grant number ATM-0851866.

  20. Flux Cancellation Leading to Solar Filament Eruptions

    NASA Astrophysics Data System (ADS)

    Popescu, R. M.; Panesar, N. K.; Sterling, A. C.; Moore, R. L.

    2016-12-01

    Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to 100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable by either magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both onboard the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions and find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two events in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field and are in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

  1. El Cobreloa: A geyser with two distinct eruption styles

    NASA Astrophysics Data System (ADS)

    Namiki, A.; Munoz, C.; Manga, M.; Hurwitz, S.; King, E.; Negri, A.; Ortega, P.; Patel, A.; Rudolph, M.

    2013-12-01

    El Cobreloa geyser has two distinct eruption styles: vigorous major eruptions, and less energetic minor eruptions. Minor eruptions splash hot water intermittently over an approximately 4 minute time period. Major eruptions begin with an eruption style similar to minor eruptions, but then transition to a voluminous and water-dominated eruption, and finally end with energetic steam discharge. The steam discharge continues for approximately 1 hour. We calculated the eruption intervals by visual observations, acoustic measurements, and ground temperature measurements. All of measurements consistently show that each eruption style has a regular interval: 4 hours and 40 minutes for major eruptions, and ~13 minutes for minor eruptions. From these observations, we infer that there are two boiling loci that source each type of eruption, one at the bottom and the other at the top of the conduit. If the bottom of the conduit is hot enough, boiling begins at the bottom of the conduit to make a steam slug. As this slug ascends in the conduit, it heats the surrounding water. If the slug rises fast enough it splashes water when it reaches the surface, creating minor eruptions. Each successive steam slug continues to heat water in the conduit until it eventually reaches the boiling temperature everywhere. Once the top of the conduit begins boiling, the energetic steam discharge begins and the boiling propagates downward. Such a process causes major eruption. Geysers are often studied as an analogue to magmatic volcanoes because it is easier to document how mass and energy transfer lead to eruptions. El Cobreloa provides insight into how the system becomes primed for large eruptions.

  2. The 2014 eruptions of Pavlof Volcano, Alaska

    USGS Publications Warehouse

    Waythomas, Christopher F.; Haney, Matthew M.; Wallace, Kristi; Cameron, Cheryl E.; Schneider, David J.

    2017-12-22

    Pavlof Volcano is one of the most frequently active volcanoes in the Aleutian Island arc, having erupted more than 40 times since observations were first recorded in the early 1800s . The volcano is located on the Alaska Peninsula (lat 55.4173° N, long 161.8937° W), near Izembek National Wildlife Refuge. The towns and villages closest to the volcano are Cold Bay, Nelson Lagoon, Sand Point, and King Cove, which are all within 90 kilometers (km) of the volcano (fig. 1). Pavlof is a symmetrically shaped stratocone that is 2,518 meters (m) high, and has about 2,300 m of relief. The volcano supports a cover of glacial ice and perennial snow roughly 2 to 4 cubic kilometers (km3) in volume, which is mantled by variable amounts of tephra fall, rockfall debris, and pyroclastic-flow deposits produced during historical eruptions. Typical Pavlof eruptions are characterized by moderate amounts of ash emission, lava fountaining, spatter-fed lava flows, explosions, and the accumulation of unstable mounds of spatter on the upper flanks of the volcano. The accumulation and subsequent collapse of spatter piles on the upper flanks of the volcano creates hot granular avalanches, which erode and melt snow and ice, and thereby generate watery debris-flow and hyperconcentrated-flow lahars. Seismic instruments were first installed on Pavlof Volcano in the early 1970s, and since then eruptive episodes have been better characterized and specific processes have been documented with greater certainty. The application of remote sensing techniques, including the use of infrasound data, has also aided the study of more recent eruptions. Although Pavlof Volcano is located in a remote part of Alaska, it is visible from Cold Bay, Sand Point, and Nelson Lagoon, making distal observations of eruptive activity possible, weather permitting. A busy air-travel corridor that is utilized by a numerous transcontinental and regional air carriers passes near Pavlof Volcano. The frequency of air travel

  3. Complicated lichenoid drug eruption.

    PubMed

    Armour, Katherine; Lowe, Patricia

    2005-02-01

    We report a case of severe lichenoid drug eruption with multiple possible causative agents. A hepatitis C-positive male presented with a short history of painful erosions of the vermilion, lichenoid lesions on the buccal mucosa and glans penis, and erosions and lichenification of the scrotum. In addition, he had a pruritic polymorphic eruption over the scalp, trunk and limbs, comprising psoriasiform and eczematous lesions. He had received combination therapy of pegylated interferon-alpha-2a and ribavirin, along with granulocyte colony-stimulating factor for interferon-induced leucopenia, and propranolol for portal hypertension. The former three agents were ceased 3 weeks prior to presentation, but he remained on propranolol at the initial dermatology consultation. The polymorphous clinical picture was consistent with lichenoid drug eruption, which was confirmed on histology. The papulosquamous eruption responded quickly to 2 weeks of oral prednisone 25 mg daily, which was tapered to 1 mg over 3 months and then ceased. The mucosal lesions were slow to improve and required the addition of tacrolimus 0.03% solution t.d.s. for complete resolution.

  4. Addressing the needs of the telecoms industry for optical fibre communication in Africa

    NASA Astrophysics Data System (ADS)

    Leitch, Andrew W. R.; Conibear, Ann B.

    2005-10-01

    We report on a successful partnership between the Department of Physics at the Nelson Mandela Metropolitan University (NMMU) and Telkom, South Africa's national telecommunications company, to train physics students in the important fields related to optical fibre technology. The partnership, which began in 2001 and forms part of Telkom's Centre of Excellence program in South Africa, is currently being extended to other countries in Africa. The training being conducted in the Physics Department has as one of its main goals an increased understanding of polarisation mode dispersion (PMD), an effect that will ultimately limit the transmission speeds through optical fibre.

  5. 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)

  6. Sulphur-rich volcanic eruptions and stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Rampino, M. R.; Self, S.

    1984-01-01

    Data from direct measurements of stratospheric optical depth, Greenland ice-core acidity, and volcanological studies are compared, and it is shown that relatively small but sulfur-rich volcanic eruptions can have atmospheric effects equal to or even greater than much larger sulfur-poor eruptions. These small eruptions are probably the most frequent cause of increased stratospheric aerosols. The possible sources of the excess sulfur released in these eruptions are discussed.

  7. Bipolar volcanic events in ice cores and the Toba eruption at 74 ka BP (Invited)

    NASA Astrophysics Data System (ADS)

    Svensson, A.

    2013-12-01

    Acidity spikes in Greenland and Antarctic ice cores are applied as tracers of past volcanic activity. Besides providing information on the timing and magnitude of past eruptions, the acidity spikes are also widely used for synchronization of ice cores. All of the deep Greenland ice cores are thus synchronized throughout the last glacial cycle based on volcanic markers. Volcanic matching of ice cores from the two Hemispheres is much more challenging but it is feasible in periods of favourable conditions. Over the last two millennia, where ice cores are precisely dated, some 50 bipolar volcanic events have thus been identified. In order for an eruption to express a bipolar fingerprint it generally needs to be a low latitude eruption with stratospheric injection. Sometimes tephra is associated with the ice-core acidity spikes, but most often there is no tephra present in the ice. As yet, an unknown eruption occurring in 1259 AD is the only event reported to have deposited tephra in both Greenland and Antarctica. During the last glacial period bipolar volcanic matching is very challenging and very little work has been done, but recent high-resolution ice core records have the potential to provide bipolar ice core matching for some periods. Recently, Greenland and Antarctic ice cores have been linked by acidity spikes in the time window of the most recent eruption (the YTT eruption) of the Indonesian Toba volcano that is situated close to equator in Sumatra. Ash from this Toba event is widespread over large areas in Asia and has been identified as far west as Africa, but no corresponding tephra has been found in polar ice cores despite several attempts. The age of the YTT eruption is well constrained by recent Ar-Ar dating to have occurred some 74 ka ago close to the Marine Isotope Stage 4/5 boundary and close to the onset of the cold Greenland Stadial 20 and the corresponding mild Antarctic Isotopic Maxima 19 and 20. Surprisingly, no single outstanding acidity spike

  8. Characterization of pyroclastic deposits and pre-eruptive soils following the 2008 eruption of Kasatochi Island Volcano, Alaska

    USGS Publications Warehouse

    Wang, B.; Michaelson, G.; Ping, C.-L.; Plumlee, G.; Hageman, P.

    2010-01-01

    The 78 August 2008 eruption of Kasatochi Island volcano blanketed the island in newly generated pyroclastic deposits and deposited ash into the ocean and onto nearby islands. Concentrations of water soluble Fe, Cu, and Zn determined from a 1:20 deionized water leachate of the ash were sufficient to provide short-term fertilization of the surface ocean. The 2008 pyroclastic deposits were thicker in concavities at bases of steeper slopes and thinner on steep slopes and ridge crests. By summer 2009, secondary erosion had exposed the pre-eruption soils along gulley walls and in gully bottoms on the southern and eastern slopes, respectively. Topographic and microtopographic position altered the depositional patterns of the pyroclastic flows and resulted in pre-eruption soils being buried by as little as 1 m of ash. The different erosion patterns gave rise to three surfaces on which future ecosystems will likely develop: largely pre-eruptive soils; fresh pyroclastic deposits influenced by shallowly buried, pre-eruptive soil; and thick (>1 m) pyroclastic deposits. As expected, the chemical composition differed between the pyroclastic deposits and the pre-eruptive soils. Pre-eruptive soils hold stocks of C and N important for establishing biota that are lacking in the fresh pyroclastic deposits. The pyroclastic deposits are a source for P and K but have negligible nutrient holding capacity, making these elements vulnerable to leaching loss. Consequently, the pre-eruption soils may also represent an important long-term P and K source. ?? 2010 Regents of the University of Colorado.

  9. Vent Processes and Deposits of a Hiatus in a Violent Eruption: Quilotoa Volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Best, J. A.; Bustillos, J.; Ort, M. H.; Cashman, K. V.; Mothes, P. A.; di Muro, A.; Rosi, M.

    2009-12-01

    high proportion of stained fragments in U2b requires a different, possibly hydrothermal, source. We interpret the lava lapilli of U2c and U3 as being from a single explosion, perhaps the opening of a new vent, and thus they indicate that the eruption was continuous from U2b through U3. Our current hypothesis is that, as the U1 eruption ended, acidic gas streamed through the material clogging the vent. This elutriated vitric material that eventually formed a cap on the system. As the U3 magma began its ascent, gas flux increased, leading to explosions that gradually removed the vitric cap and depositing the vitric U2a. Then, more continuous gas streaming led to the development of an pulsatory eruption column that carried the hot stained crystals and lithic fragments into a convecting column and eventual deposition as fallout of U2b, which was then followed by the establishment of the U3 eruption column.

  10. Flux Cancelation: The Key to Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Panesar, Navdeep K.; Sterling, Alphonse; Moore, Ronald; Chakrapani, Prithi; Innes, Davina; Schmit, Don; Tiwari, Sanjiv

    2017-01-01

    Solar coronal jets are magnetically channeled eruptions that occur in all types of solar environments (e.g. active regions, quiet-Sun regions and coronal holes). Recent studies show that coronal jets are driven by the eruption of small-scare filaments (minifilaments). Once the eruption is underway magnetic reconnection evidently makes the jet spire and the bright emission in the jet base. However, the triggering mechanism of these eruptions and the formation mechanism of the pre-jet minifilaments are still open questions. In this talk, mainly using SDO/AIA (Solar Dynamics Observatory / Atmospheric Imaging Assembly) and SDO/HIM (Solar Dynamics Observatory / Helioseismic and Magnetic Imager) data, first I will address the question: what triggers the jet-driving minifilament eruptions in different solar environments (coronal holes, quiet regions, active regions)? Then I will talk about the magnetic field evolution that produces the pre-jet minifilaments. By examining pre-jet evolutionary changes in line-of-sight HMI magnetograms while examining concurrent EUV (Extreme Ultra-Violet) images of coronal and transition-region emission, we find clear evidence that flux cancelation is the main process that builds pre-jet minifilaments, and is also the main process that triggers the eruptions. I will also present results from our ongoing work indicating that jet-driving minifilament eruptions are analogous to larger-scare filament eruptions that make flares and CMEs (Coronal Mass Ejections). We find that persistent flux cancellation at the neutral line of large-scale filaments often triggers their eruptions. From our observations we infer that flux cancelation is the fundamental process from the buildup and triggering of solar eruptions of all sizes.

  11. X-ray and EUV Observations of CME Eruption Onset

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.

    2004-01-01

    Why Coronal Mass Ejections (CMEs) erupt is a major outstanding puzzle of solar physics. Signatures observable at the earliest stages of eruption onset may hold precious clues about the onset mechanism. We present observations from SOHO/EIT and from TRACE in EUV, and from Yohkoh/SXT in soft X-rays of the pre-eruption and eruption phases of CME expulsion, along with the eruption's magnetic setting found from SOHO/MDI magnetograms. Most of our events involve clearly-observable filament eruptions and multiple neutral lines, and we use the magnetic settings and motions of the filaments to help infer the geometry and behavior of the associated erupting magnetic fields. Pre-eruption and early-eruption signatures include a relatively slow filament rise prior to eruption, and intensity "dimmings" and brightenings, both in the immediate neighborhood of the "core" (location of greatest magnetic shear) of the erupting fields and at locations remote from the core. These signatures and their relative timings place observational constraints on eruption mechanisms; our recent work has focused on implications for the so-called "tether cutting" and "breakout" models, but the same observational constraints are applicable to any model.

  12. The 1997 eruption of Okmok Volcano, Alaska: A synthesis of remotely sensed imagery

    USGS Publications Warehouse

    Patrick, M.R.; Dehn, J.; Papp, K.R.; Lu, Z.; Dean, K.; Moxey, L.; Izbekov, P.; Guritz, R.

    2003-01-01

    Okmok Volcano, in the eastern Aleutian Islands, erupted in February and March of 1997 producing a 6-km-long lava flow and low-level ash plumes. This caldera is one of the most active in the Aleutian Arc, and is now the focus of international multidisciplinary studies. A synthesis of remotely sensed data (AirSAR, derived DEMs, Landsat MSS and ETM+ data, AVHRR, ERS, JERS, Radarsat) has given a sequence of events for the virtually unobserved 1997 eruption. Elevation data from the AirSAR sensor acquired in October 2000 over Okmok were used to create a 5-m resolution DEM mosaic of Okmok Volcano. AVHRR nighttime imagery has been analyzed between February 13 and April 11, 1997. Landsat imagery and SAR data recorded prior to and after the eruption allowed us to accurately determine the extent of the new flow. The flow was first observed on February 13 without precursory thermal anomalies. At this time, the flow was a large single lobe flowing north. According to AVHRR Band 3 and 4 radiance data and ground observations, the first lobe continued growing until mid to late March, while a second, smaller lobe began to form sometime between March 11 and 12. This is based on a jump in the thermal and volumetric flux determined from the imagery, and the physical size of the thermal anomalies. Total radiance values waned after March 26, indicating lava effusion had ended and a cooling crust was growing. The total area (8.9 km2), thickness (up to 50 m) and volume (1.54×108 m3) of the new lava flow were determined by combining observations from SAR, Landsat ETM+, and AirSAR DEM data. While the first lobe of the flow ponded in a pre-eruption depression, our data suggest the second lobe was volume-limited. Remote sensing has become an integral part of the Alaska Volcano Observatory’s monitoring and hazard mitigation efforts. Studies like this allow access to remote volcanoes, and provide methods to monitor potentially dangerous ones.

  13. Two-Stage Magma Mixing and Initial Phase of the 1667 Plinian Eruption of Tarumai Volcano

    NASA Astrophysics Data System (ADS)

    Tomiya, A.; Takeuchi, S.

    2009-12-01

    25, Mg/Mn > 10 (type-3) with no type-1 (classification based on Nakagawa et al. (2006)); magnetite inclusions in pyroxene phenocrysts in b8-bottom are, however, type-1. According to the observations, we propose two-stage magma mixing as follows. Prior to the 1667 eruption, there are high-T mafic magma with olivine, calcic plagioclase and type-3 magnetite, and low-T main magma with two pyroxenes, other types of plagioclase and type-1 magnetite (and few ilmenite). The first-stage mixing between the two magmas formed the precursory hybrid magma, but could not prompt the magma to erupt immediately. In the hybrid magma, type-1 and -3 magnetite rehomogenized into type-2 due to rapid cation diffusion, but magnetite inclusions in pyroxene remained type-1. Then, the second-stage mixing between the hybrid magma and the high-T magma occurred, and just after the mixing (with no rehomogenization of type-3 magnetite) the eruption began. Following the hybrid magma (b8-bottom), the main magma erupted. Considering the diffusion coefficients of Ti and Mg in magnetite, the period between the two mixings was several years, whereas the period between the second mixing and the eruption was less than weeks. The two-stage mixing of high-T magma enabled the high-viscosity phenocryst-rich magma to erupt.

  14. 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.

  15. 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.

  16. 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.

  17. The Novarupta-Katmai eruption of 1912 - largest eruption of the twentieth century; centennial perspectives

    USGS Publications Warehouse

    Hildreth, Wes; Fierstein, Judy

    2012-01-01

    The explosive outburst at Novarupta (Alaska) in June 1912 was the 20th century's most voluminous volcanic eruption. Marking its centennial, we illustrate and document the complex eruptive sequence, which was long misattributed to nearby Mount Katmai, and how its deposits have provided key insights about volcanic and magmatic processes. It was one of the few historical eruptions to produce a collapsed caldera, voluminous high-silica rhyolite, wide compositional zonation (51-78 percent SiO2), banded pumice, welded tuff, and an aerosol/dust veil that depressed global temperature measurably. It emplaced a series of ash flows that filled what became the Valley of Ten Thousand Smokes, sustaining high-temperature metal-transporting fumaroles for a decade. Three explosive episodes spanned ~60 hours, depositing ~17 km3 of fallout and 11±2 km3 of ignimbrite, together representing ~13.5 km3 of zoned magma. No observers were nearby and no aircraft were in Alaska, and so the eruption narrative was assembled from scattered villages and ship reports. Because volcanology was in its infancy and the early investigations (1915-23) were conducted under arduous expeditionary conditions, many provocative misapprehensions attended reports based on those studies. Fieldwork at Katmai was not resumed until 1953, but, since then, global advances in physical volcanology and chemical petrology have gone hand in hand with studies of the 1912 deposits, clarifying the sequence of events and processes and turning the eruption into one of the best studied in the world. To provide perspective on this century-long evolution, we describe the geologic and geographic setting of the eruption - in a remote, sparsely inhabited wilderness; we review the cultural and scientific contexts at the time of the eruption and early expeditions; and we compile a chronology of the many Katmai investigations since 1912. Products of the eruption are described in detail, including eight layers of regionwide fallout

  18. Eruption of Shiveluch Volcano, Kamchatka Peninsula

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On March 29, 2007, the Shiveluch Volcano on the Russian Federation's Kamchatka Peninsula erupted. According to the Alaska Volcano Observatory the volcano underwent an explosive eruption between 01:50 and 2:30 UTC, sending an ash cloud skyward roughly 9,750 meters (32,000 feet), based on visual estimates. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying onboard NASA's Aqua satellite took this picture at 02:00 UTC on March 29. The top image shows the volcano and its surroundings. The bottom image shows a close-up view of the volcano at 250 meters per pixel. Satellites often capture images of volcanic ash plumes, but usually as the plumes are blowing away. Plumes have been observed blowing away from Shiveluch before. This image, however, is different. At the time the Aqua satellite passed overhead, the eruption was recent enough (and the air was apparently still enough) that the ash cloud still hovered above the summit. In this image, the bulbous cloud casts its shadow northward over the icy landscape. Volcanic ash eruptions inject particles into Earth's atmosphere. Substantial eruptions of light-reflecting particles can reduce temperatures and even affect atmospheric circulation. Large eruptions impact climate patterns for years. A massive eruption of the Tambora Volcano in Indonesia in 1815, for instance, earned 1816 the nickname 'the year without a summer.' Shiveluch is a stratovolcano--a steep-sloped volcano composed of alternating layers of solidified ash, hardened lava, and volcanic rocks. One of Kamchatka's largest volcanoes, it sports a summit reaching 3,283 meters (10,771 feet). Shiveluch is also one of the peninsula's most active volcanoes, with an estimated 60 substantial eruptions in the past 10,000 years.

  19. ASTER Images Merapi Continuing Eruption

    NASA Image and Video Library

    2010-11-18

    This thermal infrared image from NASA Terra spacecraft of Merapi continuing eruption has been processed to reveal the dominant presence of volcanic ash in the eruption plume and clouds, displayed in dark red. The warm volcanic flow appears bright.

  20. Impact of volcanic plume emissions on rain water chemistry during the January 2010 Nyamuragira eruptive event: implications for essential potable water resources.

    PubMed

    Cuoco, Emilio; Tedesco, Dario; Poreda, Robert J; Williams, Jeremy C; De Francesco, Stefano; Balagizi, Charles; Darrah, Thomas H

    2013-01-15

    On January 2, 2010 the Nyamuragira volcano erupted lava fountains extending up to 300 m vertically along an ~1.5 km segment of its southern flank cascading ash and gas on nearby villages and cities along the western side of the rift valley. Because rain water is the only available potable water resource within this region, volcanic impacts on drinking water constitutes a major potential hazard to public health within the region. During the 2010 eruption, concerns were expressed by local inhabitants about water quality and feelings of physical discomfort (e.g. nausea, bloating, indigestion, etc.) after consuming rain water collected after the eruption began. We present the elemental and ionic chemistry of drinking water samples collected within the region on the third day of the eruption (January 5, 2010). We identify a significant impact on water quality associated with the eruption including lower pH (i.e. acidification) and increases in acidic halogens (e.g. F(-) and Cl(-)), major ions (e.g. SO(4)(2-), NH(4)(+), Na(+), Ca(2+)), potentially toxic metals (e.g. Al(3+), Mn(2+), Cd(2+), Pb(2+), Hf(4+)), and particulate load. In many cases, the water's composition significantly exceeds World Health Organization (WHO) drinking water standards. The degree of pollution depends upon: (1) ash plume direction and (2) ash plume density. The potential negative health impacts are a function of the water's pH, which regulates the elements and their chemical form that are released into drinking water. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. The variation of magma discharge during basaltic eruptions

    NASA Technical Reports Server (NTRS)

    Wadge, G.

    1981-01-01

    The different types of magmatic flow in basaltic eruptions are discussed, and processes explaining the eruptive history of specific volcanoes are investigated. The effusion rate curve is divided into waxing and waning flow parts, and the ideal, elastic response of the reservoir in the waning phase is analytically shown. Historical eruption rates of Mauna Loa, Kilauea, and Etna are presented, demonstrating that for each volcano there is a trend of decreasing rate with increasing duration of eruption, a relationship not predicted by a simple elastic model of magma release. The eruptive histories of these volcanoes is explained by the processes of modification of the eruptive conduits and the continued supply of magma from depth during eruption. Discharge variations from Paricutin, Hekla, and Kilauea Iki are discussed in detail.

  2. 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.

  3. 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.

  4. Large Prominence Eruption (October 3, 2014)

    NASA Image and Video Library

    2017-12-08

    The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs. Credit: NASA/Goddard/STEREO The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs.

  5. 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.

  6. Naples between two fires: eruptive scenarios for the next eruptions by an integrated volcanological-probabilistic approach.

    NASA Astrophysics Data System (ADS)

    Mastrolorenzo, G.; Pappalardo, L.; de Natale, G.; Troise, C.; Rossano, S.; Panizza, A.

    2009-04-01

    Probabilistic approaches based on available volcanological data from real eruptions of Campi Flegrei and Somma-Vesuvius, are assembled in a comprehensive assessment of volcanic hazards at the Neapolitan area. This allows to compare the volcanic hazards related to the different types of events, which can be used for evaluating the conditional probability of flows and falls hazard in case of a volcanic crisis. Hazard maps are presented, based on a rather complete set of numerical simulations, produced using field and laboratory data as input parameters relative to a large range (VEI 1 to 5) of fallout and pyroclastic-flow events and their relative occurrence. The results allow us to quantitatively evaluate and compare the hazard related to pyroclastic fallout and density currents (PDCs) at the Neapolitan volcanoes and their surroundings, including the city of Naples. Due to its position between the two volcanic areas, the city of Naples is particularly exposed to volcanic risk from VEI>2 eruptions, as recorded in the local volcanic succession. Because dominant wind directions, the area of Naples is particularly prone to fallout hazard from Campi Flegrei caldera eruptions in the VEI range 2-5. The hazard from PDCs decreases roughly radially with distance from the eruptive vents and is strongly controlled by the topographic heights. Campi Flegrei eruptions are particularly hazardous for Naples, although the Camaldoli and Posillipo hills produce an effective barrier to propagation to the very central part of Naples. PDCs from Vesuvius eruptions with VEI>4 can cover the city of Naples, whereas even VEI>3 eruptions have a moderate fallout hazard there.

  7. Explosive Volcanic Eruptions from Linear Vents on Earth, Venus and Mars: Comparisons with Circular Vent Eruptions

    NASA Technical Reports Server (NTRS)

    Glaze, Lori S.; Baloga, Stephen M.; Wimert, Jesse

    2010-01-01

    Conditions required to support buoyant convective plumes are investigated for explosive volcanic eruptions from circular and linear vents on Earth, Venus, and Mars. Vent geometry (linear versus circular) plays a significant role in the ability of an explosive eruption to sustain a buoyant plume. On Earth, linear and circular vent eruptions are both capable of driving buoyant plumes to equivalent maximum rise heights, however, linear vent plumes are more sensitive to vent size. For analogous mass eruption rates, linear vent plumes surpass circular vent plumes in entrainment efficiency approximately when L(sub o) > 3r(sub o) owing to the larger entrainment area relative to the control volume. Relative to circular vents, linear vents on Venus favor column collapse and the formation of pyroclastic flows because the range of conditions required to establish and sustain buoyancy is narrow. When buoyancy can be sustained, however, maximum plume heights exceed those from circular vents. For current atmospheric conditions on Mars, linear vent eruptions are capable of injecting volcanic material slightly higher than analogous circular vent eruptions. However, both geometries are more likely to produce pyroclastic fountains, as opposed to convective plumes, owing to the low density atmosphere. Due to the atmospheric density profile and water content on Earth, explosive eruptions enjoy favorable conditions for producing sustained buoyant columns, while pyroclastic flows would be relatively more prevalent on Venus and Mars. These results have implications for the injection and dispersal of particulates into the planetary atmosphere and the ability to interpret the geologic record of planetary volcanism.

  8. Complex dynamics of small-moderate volcanic events: the example of the 2011 rhyolitic Cordón Caulle eruption, Chile

    NASA Astrophysics Data System (ADS)

    Pistolesi, Marco; Cioni, Raffaello; Bonadonna, Costanza; Elissondo, Manuela; Baumann, Valerie; Bertagnini, Antonella; Chiari, Laura; Gonzales, Rafael; Rosi, Mauro; Francalanci, Lorella

    2015-01-01

    After decades of repose, Puyehue-Cordón Caulle Volcano (Chile) erupted in June 2011 following a month of continuously increasing seismic activity. The eruption dispersed a large volume of rhyolitic tephra over a wide area and was characterized by complex dynamics. During the initial climactic phase of the eruption (24-30 h on 4-5 June), 11-14-km-high plumes dispersed most of the erupted tephra eastward towards Argentina, reaching as far as the Atlantic Ocean. This first eruptive phase was followed by activity of lower intensity, leading to the development of a complex stratigraphic sequence, mainly due to rapid shifts in wind direction and eruptive style. The resulting tephra deposits consist of 13 main layers grouped into four units. Each layer was characterized based on its dispersal direction, sedimentological features, and on the main characteristics of the juvenile fraction (texture, density, petrography, chemistry). The lowest part of the eruptive sequence (Unit I), corresponding to the tephra emitted between 4 and 5 June, is composed of alternating lapilli layers with a total estimated volume of ca. 0.75 km3; these layers record the highest intensity phase, during which a bent-over plume dispersed tephra towards the southeast-east, with negligible up-wind sedimentation. Products emitted during 5-6 June (Unit II) signaled an abrupt shift in wind direction towards the north, leading to the deposition of a coarse ash deposit in the northern sector (ca. 0.21 km3 in volume), followed by a resumption of easterly directed winds. A third phase (Unit III) began on 7 June and resulted in tephra deposits in the eastern sector and ballistic bombs around the vent area. A final phase (Unit IV) started after 15 June and was characterized by the emission of fine-grained white tephra from ash-charged plumes during low-level activity and the extrusion of a viscous lava flow. Timing and duration of the first eruptive phases were constrained based on comparison of the

  9. 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

  10. 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.

  11. Eruptive history and tectonic setting of Medicine Lake Volcano, a large rear-arc volcano in the southern Cascades

    USGS Publications Warehouse

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

    2008-01-01

    Medicine Lake Volcano (MLV), located in the southern Cascades ??? 55??km east-northeast of contemporaneous Mount Shasta, has been found by exploratory geothermal drilling to have a surprisingly silicic core mantled by mafic lavas. This unexpected result is very different from the long-held view derived from previous mapping of exposed geology that MLV is a dominantly basaltic shield volcano. Detailed mapping shows that < 6% of the ??? 2000??km2 of mapped MLV lavas on this southern Cascade Range shield-shaped edifice are rhyolitic and dacitic, but drill holes on the edifice penetrated more than 30% silicic lava. Argon dating yields ages in the range ??? 475 to 300??ka for early rhyolites. Dates on the stratigraphically lowest mafic lavas at MLV fall into this time frame as well, indicating that volcanism at MLV began about half a million years ago. Mafic compositions apparently did not dominate until ??? 300??ka. Rhyolite eruptions were scarce post-300??ka until late Holocene time. However, a dacite episode at ??? 200 to ??? 180??ka included the volcano's only ash-flow tuff, which was erupted from within the summit caldera. At ??? 100??ka, compositionally distinctive high-Na andesite and minor dacite built most of the present caldera rim. Eruption of these lavas was followed soon after by several large basalt flows, such that the combined area covered by eruptions between 100??ka and postglacial time amounts to nearly two-thirds of the volcano's area. Postglacial eruptive activity was strongly episodic and also covered a disproportionate amount of area. The volcano has erupted 9 times in the past 5200??years, one of the highest rates of late Holocene eruptive activity in the Cascades. Estimated volume of MLV is ??? 600??km3, giving an overall effusion rate of ??? 1.2??km3 per thousand years, although the rate for the past 100??kyr may be only half that. During much of the volcano's history, both dry HAOT (high-alumina olivine tholeiite) and hydrous calcalkaline

  12. Characteristics of EIT Dimmings in Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Adams, Mitzi; Sterling, A. C.

    2006-01-01

    Intensity "dimmings" in coronal images are a key feature of solar eruptions. Such dimmings are likely the source locations for much of the material expelled in coronal mass ejections (CMEs). Characteristics such as the timing of the dimmings with respect to the onset of other eruption signatures, and the location of the dimmings in the context of the magnetic field environment of the erupting region, are indicative of the mechanism leading to the eruption. We examine dimmings of six eruptions in images from the EUV Imaging Telescope (EIT) on SOHO, along with supplementary soft X-ray (SXR) data from GOES and the SXR Telescope (SXT) on Yohkoh. We examine the timing of the dimming onset and compare with the time of EUV and SXR brightening and determine the timescale for the recovery from dimming for each event. With line-of-sight photospheric magnetograms from the MDI instrument on SOHO, we determine the magnetic structure of the erupting regions and the locations of the dimmings in those regions. From our analysis we consider which mechanism likely triggered each eruption: internal tether cutting, external tether cutting ("breakout"), loss of equilibrium, or some other mechanism.

  13. Plasma Evolution within an Erupting Coronal Cavity

    NASA Astrophysics Data System (ADS)

    Long, David M.; Harra, Louise K.; Matthews, Sarah A.; Warren, Harry P.; Lee, Kyoung-Sun; Doschek, George A.; Hara, Hirohisa; Jenkins, Jack M.

    2018-03-01

    Coronal cavities have previously been observed to be associated with long-lived quiescent filaments and are thought to correspond to the associated magnetic flux rope. Although the standard flare model predicts a coronal cavity corresponding to the erupting flux rope, these have only been observed using broadband imaging data, restricting an analysis to the plane-of-sky. We present a unique set of spectroscopic observations of an active region filament seen erupting at the solar limb in the extreme ultraviolet. The cavity erupted and expanded rapidly, with the change in rise phase contemporaneous with an increase in nonthermal electron energy flux of the associated flare. Hot and cool filamentary material was observed to rise with the erupting flux rope, disappearing suddenly as the cavity appeared. Although strongly blueshifted plasma continued to be observed flowing from the apex of the erupting flux rope, this outflow soon ceased. These results indicate that the sudden injection of energy from the flare beneath forced the rapid eruption and expansion of the flux rope, driving strong plasma flows, which resulted in the eruption of an under-dense filamentary flux rope.

  14. Bárðarbunga volcano - post-eruption trends following the Holuhraun eruption in 2014-2015

    NASA Astrophysics Data System (ADS)

    Jónsdóttir, Kristín; Hooper, Andrew; Jónasson, Kristján; Vogfjörð, Kristín; Tumi Gudmundsson, Magnús; Hjorleifsdóttir, Vala; Rodríguez-Cardozo, Felix R.; Sigmundsson, Freysteinn; Ófeigsson, Benedikt G.; Parks, Michelle M.; Roberts, Matthew; Gudmundsson, Gunnar B.; Hognadóttir, Thordis; Pfeffer, Melissa A.; Geirsson, Halldór; Barsotti, Sara; Oddsson, Bjorn

    2017-04-01

    The Bárdarbunga volcano in central Iceland experienced a major unrest, lateral dyking, and eruption in August 2014-February 2015. The eruption was accompanied by caldera collapse, a truly rare event that has not been monitored in such detail before, providing a unique opportunity for better understanding the volcanic structure and processes. The collapse was extensive as the 8x11 km caldera gradually subsided and a subsidence bowl up to 65 m deep was formed, while about 1.8 km3 of magma drained laterally along a subterranean path, forming a flood basalt 47 km northeast of the volcano. The collapse was accompanied by high rates of seismicity and 80 earthquakes between M5-M5.8 were recorded. Using various geophysical and geochemical data, together with modelling, the magma reservoir has been estimated to reside at about 8-12 km depth beneath the caldera and recent findings show that the subsidence was driven by a feedback between the pressure of the piston-like block overlying the reservoir, and the 47 km long magma outflow path. The collapse and magma outflow gradually declined until the eruption ended on the 27th February 2015. After the end of the eruption, GPS deformation data show horizontal movements that seem to be in line with an inflation signal centered at the caldera, but the pattern is more complicated than during the co-eruptive period. The seismicity continued to decline, both in the far end of the dyke as well as within the caldera. However, in September 2015 seismicity within the caldera started to increase again. Interestingly, this increase was identified in terms of increased earthquake magnitudes while earthquake rate remained relatively constant. This resulted in a volcanic earthquake catalog with the highest seismic moment release rate ever recorded in Iceland during times of volcanic quiescence. Here we present a seismic waveform correlation analysis which reveals a dramatic change occurring between February and May 2015, where the earthquakes

  15. Development Communication and the New Millennium: Which Way for Africa?

    ERIC Educational Resources Information Center

    Moemeka, Andrew A.

    Since development communication began in Africa in the 1950s, it has been based on the erroneous belief, first, that development meant westernization and, later, that it meant modernization. This led to two working assumptions: that money and educated (qualified) personnel were all that was needed to create development; and that all efforts should…

  16. Geochemical Composition of Volcanic Rocks from the May 2003 Eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Wade, J. A.; Plank, T.; Stern, R.; Hilton, D.; Fischer, T. P.; Moore, R.; Trusdell, F.; Sako, M.

    2003-12-01

    The first historical eruption of Anatahan volcano began on May 10, 2003, from the easternmost of the island's two craters. Samples of tephra, scoria, and bombs, collected in May by a MARGINS-supported rapid-response team, were analyzed for 34 trace elements by solution ICP-MS at Boston University and Sr-Nd-Pb isotopic composition at the University of Texas-Dallas. The new eruptive materials can be compared with an extensive suite of pre-existing volcanics (basalts through dacites) from Anatahan sampled by the USGS in 1990 and 1992, and analyzed by XRF and INAA. While most Mariana volcanoes erupt basalts and basaltic andesites, Anatahan is unusual for erupting a wide range of compositions, from basalt to dacite, and thus provides the best opportunity for addressing questions of magma evolution in this classic island arc. The newly erupted scoria and pumice are andesites and dacites that are among the most silicic materials erupted in the northern Mariana islands. The recent eruptives are highly homogeneous; 13 samples vary by only 3-5% relative standard deviation for incompatible trace elements. Isotopic compositions (0.703450 +/- 2 87Sr/86Sr and 18.806 +/- 5 206Pb/204Pb) are within the range of previously measured samples from Anatahan and other volcanic centers in the Marianas. The combined dataset for Anatahan defines virtually a single liquid line of descent. This is consistent with nearly-parallel REE patterns, and small variations in the ratios of the most incompatible trace elements (e.g., Th/Rb varies by <10% over the entire fractionation trend). Low values of Th/La and Th/Zr in Anatahan volcanics provide evidence against partial melting of crustal material as a source of the silicic magmas, as these ratios are highly senstive to apatite- and zircon- saturated crustal melts. Instead, the basalts, andesites and dacites of Anatahan appear to be related predominantly by crystal fractionation with little evidence for assimilation of crustal melts. The new data

  17. Seasonal variations of volcanic eruption frequencies

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

    Do volcanic eruptions have a tendency to occur more frequently in the months of May and June? Some past evidence suggests that they do. The present study, based on the new eruption catalog of Simkin et al.(1981), investigates the monthly statistics of the largest eruptions, grouped according to explosive magnitude, geographical latitude, and year. At the 2-delta level, no month-to-month variations in eruption frequency are found to be statistically significant. Examination of previously published month-to-month variations suggests that they, too, are not statistically significant. It is concluded that volcanism, at least averaged over large portions of the globe, is probably not periodic on a seasonal or annual time scale.

  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. Theoretical mechanisms for solar eruptions

    NASA Astrophysics Data System (ADS)

    Lin, Jun

    This thesis presents new theoretical models of solar eruptions which are derived from older models that involve a loss of equilibrium of the Sun's coronal magnetic field. These models consist of a magnetic flux rope nested within an arcade of magnetic loop. Prior to an eruption, the flux rope floats in the corona under a balance between magnetic compression and tension forces. When an eruption occurs, the magnetic compression exceeds the magnetic tension and causes the flux rope to be thrown outwards, away from the Sun. Three important factors which impact the occurrence and evolution of the eruptive processes are investigated. These factors are magnetic reconnection, new emerging flux, and the large scale curvature of the flux rope. First, our new results confirm that in the absence of reconnection, magnetic tension in two-dimensional configuration is always strong enough to prevent escape of the flux rope to infinity after it erupts. However, only a relatively small reconnection rate is needed to allow the flux rope to escape to infinity. Specifically, for a coronal density model that decreases exponentially with height we find that average Alfvén Mach number MA for the inflow into the reconnection site can be as small as M A = 0.005 and still be fast enough to give a plausible eruption. The best fit to observations is obtained by assuming an inflow rate on the order of MA ~ 0.1. Second, we have found that the emergence of new flux system in the vicinity of a preexisting flux rope can cause a loss of ideal-MHD equilibrium under certain circumstances. But the circumstances which lead to eruption are much richer and more complicated than commonly described in the existing literatures. Our model results suggest that the actual circumstances leading to an eruption are sensitive, not only to the polarity of the emerging region, but to several other parameters, such as its strength, distance, and area as well. The results also indicate that in general there is no

  20. Triggering of solar magnetic eruptions on various size scales

    NASA Astrophysics Data System (ADS)

    Sterling, Alphonse

    A solar eruption that produces a coronal mass ejection (CME) together with a flare is driven by the eruption of a closed-loop magnetic arcade that has a sheared-field core. Before eruption, the sheared core envelops a polarity inversion line along which cool filament material may reside. The sheared-core arcade erupts when there is a breakdown in the balance between the confining downward-directed magnetic tension of the overall arcade field and the upward-directed force of the pent-up magnetic pressure of the sheared field in the core of the arcade. What triggers the breakdown in this balance in favor of the upward-directed force is still an unsettled question. We consider several eruption examples, using imaging data from the SoHO, TRACE and Hinode satellites, and other sources, along with information about the magnetic field of the erupting regions. In several cases, observations of large-scale eruptions, where the magnetic neutral line spans ˜ few ×10,000 km, are consistent with magnetic flux cancelation being the trigger to the eruption's onset, even though the amount of flux canceled is only ˜ few percent of the total magnetic flux of the erupting region. In several other cases, an initial compact (small size-scale) eruption occurs embedded inside of a larger closed magnetic loop system, so that the smaller eruption destabilizes and causes the eruption of the much larger system. In this way, small-scale eruptive events can result in eruption of much larger-scale systems. This work was funded by NASA's Science Mission Directorate thought the Living With a Star Targeted Research and Technology Program, the Supporting Research and Program, and the Hinode project.

  1. The hazards of eruptions through lakes and seawater

    USGS Publications Warehouse

    Mastin, L.G.; Witter, J.B.

    2000-01-01

    Eruptions through crater lakes or shallow seawater, referred to here as subaqueous eruptions, present hazards from hydromagmatic explosions, such as base surges, lahars, and tsunamis, which may not exist at volcanoes on dry land. We have systematically compiled information from eruptions through surface water in order to understand the circumstances under which these hazards occur and what disastrous effects they have caused in the past. Subaqueous eruptions represent only 8% of all recorded eruptions but have produced about 20% of all fatalities associated with volcanic activity in historical time. Excluding eruptions that have resulted in about a hundred deaths or less, lahars have killed people in the largest number of historical subaqueous eruptions (8), followed by pyroclastic flows (excluding base surges; 5) tsunamis (4), and base surges (2). Subaqueous eruptions have produced lahars primarily on high (>1000 m), steep-sided volcanoes containing small (<1 km diameter) crater lakes. Tsunamis and other water waves have caused death or destroyed man-made structures only at submarine volcanoes and at Lake Taal in the Philippines. In spite of evidence that magma-water mixing makes eruptions more explosive, such explosions and their associated base surges have caused fewer deaths, and have been implicated in fewer eruptions involving large numbers of fatalities than lahars and tsunamis. The latter hazards are more deadly because they travel much farther from a volcano and inundate coastal areas and stream valleys that tend to be densely settled.

  2. 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. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  3. The Chaitén rhyolite lava dome: Eruption sequence, lava dome volumes, rapid effusion rates and source of the rhyolite magma

    USGS Publications Warehouse

    Pallister, John S.; Diefenbach, Angela K.; Burton, William C.; Munoz, Jorge; Griswold, Julia P.; Lara, Luis E.; Lowenstern, Jacob B.; Valenzuela, Carolina E.

    2013-01-01

    We use geologic field mapping and sampling, photogrammetric analysis of oblique aerial photographs, and digital elevation models to document the 2008-2009 eruptive sequence at Chaitén Volcano and to estimate volumes and effusion rates for the lava dome. We also present geochemical and petrologic data that contribute to understanding the source of the rhyolite and its unusually rapid effusion rates. The eruption consisted of five major phases: 1. An explosive phase (1-11 May 2008); 2. A transitional phase (11-31 May 2008) in which low-altitude tephra columns and simultaneous lava extrusion took place; 3. An exogenous lava flow phase (June-September 2008); 4. A spine extrusion and endogenous growth phase (October 2008-February 2009); and 5. A mainly endogenous growth phase that began after the collapse of a prominent Peléean spine on 19 February 2009 and continued until the end of the eruption (late 2009 or possibly earliest 2010). The 2008-2009 rhyolite lava dome has a total volume of approximately 0.8 km3. The effusion rate averaged 66 m3s-1 during the first two weeks and averaged 45 m3s-1 for the first four months of the eruption, during which 0.5 km3 of rhyolite lava was erupted. These are among the highest rates measured world-wide for historical eruptions of silicic lava. Chaitén’s 2008-2009 lava is phenocryst-poor obsidian and microcrystalline rhyolite with 75.3±0.3% SiO2. The lava was erupted at relatively high temperature and is remarkably similar in composition and petrography to Chaitén’s pre-historic rhyolite. The rhyolite’s normative composition plots close to that of low pressure (100-200 MPa) minimum melts in the granite system, consistent with estimates of approximately 5 to 10 km source depths based on phase equilibria and geodetic studies. Calcic plagioclase, magnesian orthopyroxene and aluminous amphibole among the sparse phenocrysts suggest derivation of the rhyolite by melt extraction from a more mafic magmatic mush. High temperature

  4. Eruption Cyst in the Neonate.

    PubMed

    de Oliveira, Alline J; Silveira, Maria Lg; Duarte, Danilo A; Diniz, Michele B

    2018-01-01

    The pediatric dental approach to the oral cavity of newborns requires special attention, as many aspects are unique and peculiar to this period of life. It is important that pediatricians and pediatric dentists be aware of the characteristics within normal newborn patterns and prepared to make a correct diagnosis of abnormalities at early stages. Congenital eruption cysts (ECs) are rarely observed in newborns, as at this stage of a child's life, tooth eruption is unusual. This study reports a case of EC treated successfully by monitoring of the lesion, without any surgical procedure. In the 4th month, the lesion had completely regressed, and the deciduous central incisors had erupted without problems. The clinical and radiographic monitoring of ECs in newborns seems to be a satisfactory management procedure, similar to what is recommended for older children. How to cite this article: de Oliveira AJ, Silveira MLG, Duarte DA, Diniz MB. Eruption Cyst in the Neonate. Int J Clin Pediatr Dent 2018;11(1):58-60.

  5. 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.

  6. Fracture Mechanics Approach to Forecasting Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Matthews, C.; Sammonds, P.; Kilburn, C.; Woo, G.

    2008-12-01

    A medium to short-term increase in the rate of volcano-tectonic earthquake events provides one of the most useful and promising tools for eruption forecasting, particularly at subduction-zone volcanoes reawakening after a long repose interval. Two basic patterns of accelerating seismicity observed prior to eruptions are exponential and faster than exponential increases with time. While theoretical and empirical models exist that can explain these observed trends, less is known about seismic unrest at volcanoes that does not end in eruption. A comprehensive model of fracturing and failure within an edifice must also explain why volcanoes do not erupt. We have developed a numerical fracture mechanical model for simulating precursory seismic sequences, associated with the opening of a new magmatic pathway to the surface. The model reproduces the basic patterns of precursory seismicity and shows that the signals produced vary according to changes in the extent of damage and in the mechanical properties of the host rock. Local stress conditions and material property distributions exist under which the model is also able to produce seismic swarms that do not lead to failure and eruption. It can therefore provide insight into factors determining whether or not a seismic crisis leads to eruption. Critically, when combined with field data this may provide information on how often 'failed' eruptions can be expected, or suggest a step towards an observational method for distinguishing between a seismic swarm leading to quiescence and a pre-eruptive seismic sequence.

  7. 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

  8. The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines

    USGS Publications Warehouse

    Newhall, Christopher G.; Hendley, James W.; Stauffer, Peter H.

    1997-01-01

    The second-largest volcanic eruption of this century, and by far the largest eruption to affect a densely populated area, occurred at Mount Pinatubo in the Philippines on June 15, 1991. The eruption produced high-speed avalanches of hot ash and gas, giant mudflows, and a cloud of volcanic ash hundreds of miles across. The impacts of the eruption continue to this day.

  9. Vent Processes and Deposits of a Hiatus in a Violent Eruption: Quilotoa Volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Best, J. A.; Bustillos, J.; Ort, M. H.; Cashman, K. V.; Mothes, P. A.; di Muro, A.; Rosi, M.

    2010-12-01

    , with the simultaneous milling of the weakened material producing the orange dust. We interpret the dense vitric lapilli ≥ -2.0 φ of U2c as being from an explosion through a lava dome, and thus they indicate that the eruption was continuous from U2c through U3. Our current hypothesis is that, as the U1 eruption ended, magma stalled deep in the conduit and degassed hot acidic gas that streamed through the material clogging the vent. This elutriated vitric material that eventually formed a cap on the system. As the U3 magma began its ascent, gas flux increased, leading to explosions that gradually removed the vitric cap and deposited the vitric U2a. Then, more continuous gas streaming led to the development of a pulsatory eruption column that carried hot crystals and vitric grains from the vent clog into a convecting column and eventual deposition as U2b fallout, which was then followed by the establishment of the U3 eruption column.

  10. Understanding and forecasting phreatic eruptions driven by magmatic degassing

    NASA Astrophysics Data System (ADS)

    Stix, John; de Moor, J. Maarten

    2018-05-01

    This paper examines phreatic eruptions which are driven by inputs of magma and magmatic gas. We synthesize data from several significant phreatic systems, including two in Costa Rica (Turrialba and Poás) which are currently highly active and hazardous. We define two endmember types of phreatic eruptions, the first (type 1) in which a deeper hydrothermal system fed by magmatic gases is sealed and produces overpressure sufficient to drive explosive eruptions, and the second (type 2) where magmatic gases are supplied via open-vent degassing to a near-surface hydrothermal system, vaporizing liquid water which drives the phreatic eruptions. The surficial source of type 2 eruptions is characteristic, while the source depth of type 1 eruptions is commonly greater. Hence, type 1 eruptions tend to be more energetic than type 2 eruptions. The first type of eruption we term "phreato-vulcanian", and the second we term "phreato-surtseyan". Some systems (e.g., Ruapehu, Poás) can produce both type 1 and type 2 eruptions, and all systems can undergo sealing at various timescales. We examine a number of precursory signals which appear to be important in understanding and forecasting phreatic eruptions; these include very long period events, banded tremor, and gas ratios, in particular H2S/SO2 and CO2/SO2. We propose that if these datasets are carefully integrated during a monitoring program, it may be possible to accurately forecast phreatic eruptions.[Figure not available: see fulltext.

  11. Satellite View of Kilauea Eruption

    NASA Image and Video Library

    2018-05-07

    This image from NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft show recent eruptions of Kilauea volcano on the island of Hawaii (the Big Island). Following days of increased seismic activity, Kilauea erupted May 3, 2018, and triggered a number of additional fissure eruptions along the East Rift Zone. The eruptions and high level of sulfur dioxide gas (SO2) prompted evacuations in the area, including the Leilani Estates subdivision near the town of Pahoa. The ASTER images, acquired on May 6, 2018, show different aspects of the eruption. A color composite depicts vegetation in red, and old lava flows in black and gray. Superimposed on the image in yellow are hotspots detected on the thermal infrared bands. The easternmost hot spots show the newly formed fissures and the lava flow spilling to the northwest. The middle spots are Pu'u O'o crater, and lava flows descending the slopes to the southeast. The westernmost area is the crater and lava lake on Kilauea's summit. The greenish area southwest of Pu'u O'o is ash deposits from its short eruption on Friday. The inset shows the massive sulfur dioxide plume is shown in yellow and yellow-green, extracted from ASTER's multiple thermal bands. A smaller, but thicker, sulfur dioxide gas plume can be seen coming from Kilauea. The prevailing trade winds blow the plumes to the southwest, out over the ocean. The images cover an area of 57.8 by 63 kilometers, and are located at 19.3 degrees North, 155.1 degrees West. https://photojournal.jpl.nasa.gov/catalog/PIA22450

  12. SOLAR MULTIPLE ERUPTIONS FROM A CONFINED MAGNETIC STRUCTURE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Jeongwoo; Chae, Jongchul; Liu, Chang

    2016-09-20

    How eruption can recur from a confined magnetic structure is discussed based on the Solar Dynamics Observatory observations of the NOAA active region 11444, which produced three eruptions within 1.5 hr on 2012 March 27. The active region (AR) had the positive-polarity magnetic fields in the center surrounded by the negative-polarity fields around. Since such a distribution of magnetic polarity tends to form a dome-like magnetic fan structure confined over the AR, the multiple eruptions were puzzling. Our investigation reveals that this event exhibits several properties distinct from other eruptions associated with magnetic fan structures: (i) a long filament encirclingmore » the AR was present before the eruptions; (ii) expansion of the open–closed boundary (OCB) of the field lines after each eruption was suggestive of the growing fan-dome structure, and (iii) the ribbons inside the closed magnetic polarity inversion line evolved in response to the expanding OCB. It thus appears that in spite of multiple eruptions the fan-dome structure remained undamaged, and the closing back field lines after each eruption rather reinforced the fan-dome structure. We argue that the multiple eruptions could occur in this AR in spite of its confined magnetic structure because the filament encircling the AR was adequate for slipping through the magnetic separatrix to minimize the damage to its overlying fan-dome structure. The result of this study provides a new insight into the productivity of eruptions from a confined magnetic structure.« less

  13. Water/magma mass fractions in phreatomagmatic eruption plumes - constraints from the Grímsvötn 2011 eruption

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Pálsson, F.; Thordarson, T.; Hoskuldsson, A.; Larsen, G.; Hognadottir, T.; Oddsson, B.; Oladottir, B. A.; Gudnason, J.

    2014-12-01

    Explosive interaction of magma and water leads to vaporization and introduces external water vapor to volcanic plumes. Theoretical considerations on the effect of external water magma ratio on volcanic plumes indicate that plume buoyancy should be enhanced by external water fractions up to at least 30%, while fractions reaching 40% should lead to plume collapse. The basaltic VEI 4 eruption of Grímsvötn in May 2011 produced a 15-20 km high eruption plume and over 100 km wide umbrella cloud. External water interacted with the magma and entered the plume from the melting out of a 100-150 m deep ice cauldron that had acquired a volume of 0.1 km3 at the end of the eruption. About 0.7 km3 of tephra was produced in the eruption whereof about half was erupted in phreatomagmatic phases and the other half in magmatic phases. During the dry, magmatic phases melting was apparently not fast enough to supply sufficient external water to the vents to control the style of activity. The only source of external water was the melting out of the ice cauldron since no changes took place in the level of the larger, subglacial lake in the center of the Grímsvötn caldera, and no meltwater was drained from the caldera. The eruption site therefore had little or no hydrological connection with the adjacent subglacial lake. Water remaining at the eruption site at the end of the eruption was miniscule compared to the amount of ice melted. Hence, most of the meltwater was vaporized and carried away as a part of the eruption plume. About one third of the thermal energy of the magma erupted was used to melt, heat up and vaporize water. A large part of this water was released from the plume through condensation and re-freezing, manifested in hail-rich tephra deposited out to several kilometers from the vent. The data indicate that the external water/tephra mass ratio in the phreatomagmatic phases was 20-25%, but similar to 5% for the predominantly magmatic phases.

  14. Analysis of data on large explosive eruptions of stratovolcanoes to constrain under-recording and eruption rates

    NASA Astrophysics Data System (ADS)

    Rougier, Jonty; Cashman, Kathy; Sparks, Stephen

    2016-04-01

    We have analysed the Large Magnitude Explosive Volcanic Eruptions database (LaMEVE) for volcanoes that classify as stratovolcanoes. A non-parametric statistical approach is used to assess the global recording rate for large (M4+). The approach imposes minimal structure on the shape of the recording rate through time. We find that the recording rates have declined rapidly, going backwards in time. Prior to 1600 they are below 50%, and prior to 1100 they are below 20%. Even in the recent past, e.g. the 1800s, they are likely to be appreciably less than 100%.The assessment for very large (M5+) eruptions is more uncertain, due to the scarcity of events. Having taken under-recording into account the large-eruption rates of stratovolcanoes are modelled exchangeably, in order to derive an informative prior distribution as an input into a subsequent volcano-by-volcano hazard assessment. The statistical model implies that volcano-by-volcano predictions can be grouped by the number of recorded large eruptions. Further, it is possible to combine all volcanoes together into a global large eruption prediction, with an M4+ rate computed from the LaMEVE database of 0.57/yr.

  15. NEW OBSERVATION OF FAILED FILAMENT ERUPTIONS: THE INFLUENCE OF ASYMMETRIC CORONAL BACKGROUND FIELDS ON SOLAR ERUPTIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Y.; Xu, Z.; Su, J.

    2009-05-01

    Failed filament eruptions not associated with a coronal mass ejection (CME) have been observed and reported as evidence for solar coronal field confinement on erupting flux ropes. In those events, each filament eventually returns to its origin on the solar surface. In this Letter, a new observation of two failed filament eruptions is reported which indicates that the mass of a confined filament can be ejected to places far from the original filament channel. The jetlike mass motions in the two failed filament eruptions are thought to be due to the asymmetry of the background coronal magnetic fields with respectmore » to the locations of the filament channels. The asymmetry of the coronal fields is confirmed by an extrapolation based on a potential field model. The obvious imbalance between the positive and negative magnetic flux (with a ratio of 1:3) in the bipolar active region is thought to be the direct cause of the formation of the asymmetric coronal fields. We think that the asymmetry of the background fields can not only influence the trajectories of ejecta, but also provide a relatively stronger confinement for flux rope eruptions than the symmetric background fields do.« less

  16. Jupiter Eruptions

    NASA Image and Video Library

    2008-01-25

    NASA Hubble Space Telescope shows detailed analysis of two continent-sized storms that erupted in Jupiter atmosphere in March 2007 shows that Jupiter internal heat plays a significant role in generating atmospheric disturbances .

  17. Interpretation of Historical Eruptions of Mt. Baekdu Volcano, Korea

    NASA Astrophysics Data System (ADS)

    Yun, S. H.; Cho, E.; Yang, I. S.

    2014-12-01

    This study is performed to find out the eruptive events of the historical period recorded in literature, which have been recognized and regarded as ones from Mt. Baekdusan, and to make volcanological interpretations of the eruptive events. Since the Millennium eruption, more than 31 eruptive events have been discovered, most of which are Plinian eruptions with volcanic ash that dispersed into the regions in the vicinity of the volcano. The minimum volume of erupted materials in 1702 is estimated to be 1.2 km3when calculated with an empirical formula using an isopach line obtained from two points 140 km away from the vent. The 1702 eruption was a paroxysmal one with VEI of 5. The historical record described a deposition of wind-modified fallout ash by movement of hot ash cloud. The 1903 record includes the event of the phreatomagmatic or vulcanian eruption that occurred within the Cheonji caldera lake. Based on the eruption records of the historical period and the 2002 precursor unrest to volcanic eruptions, Mt. Baekdusan has been evaluated and regarded as an active volcano that has the potential to erupt in the future. This research was supported by a grant [NEMA-BAEKDUSAN-2012-1-2] from the Volcanic Disaster Preparedness Research Center sponsored by National Emergency Management Agency of Korea. T

  18. Integrating field, textural, and geochemical monitoring to track eruption triggers and dynamics: a case study from Piton de la Fournaise

    NASA Astrophysics Data System (ADS)

    Gurioli, Lucia; Di Muro, Andrea; Vlastélic, Ivan; Moune, Séverine; Thivet, Simon; Valer, Marina; Villeneuve, Nicolas; Boudoire, Guillaume; Peltier, Aline; Bachèlery, Patrick; Ferrazzini, Valérie; Métrich, Nicole; Benbakkar, Mhammed; Cluzel, Nicolas; Constantin, Christophe; Devidal, Jean-Luc; Fonquernie, Claire; Hénot, Jean-Marc

    2018-04-01

    The 2014 eruption at Piton de la Fournaise (PdF), La Réunion, which occurred after 41 months of quiescence, began with surprisingly little precursory activity and was one of the smallest so far observed at PdF in terms of duration (less than 2 days) and volume (less than 0.4 × 106 m3). The pyroclastic material was composed of golden basaltic pumice along with fluidal, spiny iridescent and spiny opaque basaltic scoria. Density analyses performed on 200 lapilli reveal that while the spiny opaque clasts are the densest (1600 kg m-3) and most crystalline (55 vol. %), the golden pumices are the least dense (400 kg m-3) and crystalline (8 vol. %). The connectivity data indicate that the fluidal and golden (Hawaiian-like) clasts have more isolated vesicles (up to 40 vol. %) than the spiny (Strombolian-like) clasts (0-5 vol. %). These textural variations are linked to primary pre-eruptive magma storage conditions. The golden and fluidal fragments track the hotter portion of the melt, in contrast to the spiny fragments and lava that mirror the cooler portion of the shallow reservoir. Exponential decay of the magma ascent and output rates through time revealed depressurization of the source during which a stratified storage system was progressively tapped. Increasing syn-eruptive degassing and melt-gas decoupling led to a decrease in the explosive intensity from early fountaining to Strombolian activity. The geochemical results confirm the absence of new input of hot magma into the 2014 reservoir and confirm the emission of a single shallow, differentiated magma source, possibly related to residual magma from the November 2009 eruption. Fast volatile exsolution and crystal-melt separation (second boiling) were triggered by deep pre-eruptive magma transfer and stress field change. Our study highlights the possibility that shallow magma pockets can be quickly reactivated by deep processes without mass or energy (heat) transfer and produce hazardous eruptions with only short

  19. 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.

  20. Understanding the eruption mechanisms of the explosive Bellecombe Eruptions on Piton de la Fournaise, La Réunion

    NASA Astrophysics Data System (ADS)

    Morgan, K.; Ort, M. H.; Di Muro, A.; Parnell, R. A.; Huff, W. D.

    2017-12-01

    Piton de la Fournaise (PdF) is an active basaltic volcano on La Réunion island. The Bellecombe Tephra was deposited from at least three unusually explosive eruptions between 3000-5000 ka. The Bellecombe eruptions were interpreted recently to have been due to rapid depressurization of the hydrothermal system when a deep fracture opened after lateral, seaward-directed sliding of the eastern flank, late in a large effusive eruption. This project tests this hypothesis by physically, mineralogically, and chemically characterizing the Bellecombe Tephra to look for evidence of the involvement of the PdF hydrothermal system in the eruptions and understand where the eruptions initiated. The Bellecombe tephra consists of three units separated by incipient soils. Both the Upper and Lower Bellecombe deposits are mostly medium to very fine ash. Lower Bellecombe deposits, from the first two eruptions, are mostly beds of glassy ash containing minor lithic grains and olivine crystals. Hydrothermal minerals, mostly smectite, are present in a few Lower Bellecombe beds. Since these minerals are only present in some beds, the smectite formed before deposition rather than as a product of surficial alteration. The Upper Bellecombe deposits record a third eruption and vary between clast-supported crystal- and lithic-rich lapilli beds and ash beds with abundant ash pellets. The crystals are mostly olivine, with lesser pyroxene and plagioclase and sparse hydrothermal quartz. Gabbro and oceanite clasts are abundant and trachytic pumice rare in these deposits. Hydrothermal minerals are common in most Upper Bellecombe beds. The presence of smectite in some of the Lower Bellecombe beds suggests these deposits came from a system below 200 ºC. Clays in the Upper Bellecombe beds - smectite and mixed layer R0 illite/smectite - imply a system at 40-140 ºC. The hydrothermal system was involved, but might not have been the primary impetus for these eruptions, since hydrothermal minerals are not

  1. The frequency of explosive volcanic eruptions in Southeast Asia.

    PubMed

    Whelley, Patrick L; Newhall, Christopher G; Bradley, Kyle E

    There are ~750 active and potentially active volcanoes in Southeast Asia. Ash from eruptions of volcanic explosivity index 3 (VEI 3) and smaller pose mostly local hazards while eruptions of VEI ≥ 4 could disrupt trade, travel, and daily life in large parts of the region. We classify Southeast Asian volcanoes into five groups, using their morphology and, where known, their eruptive history and degassing style. Because the eruptive histories of most volcanoes in Southeast Asia are poorly constrained, we assume that volcanoes with similar morphologies have had similar eruption histories. Eruption histories of well-studied examples of each morphologic class serve as proxy histories for understudied volcanoes in the class. From known and proxy eruptive histories, we estimate that decadal probabilities of VEI 4-8 eruptions in Southeast Asia are nearly 1.0, ~0.6, ~0.15, ~0.012, and ~0.001, respectively.

  2. Familial polymorphous cold eruption.

    PubMed

    Martin, S; Eastern, J; Knox, J M

    1981-02-01

    An erythematous, burning papular eruption, constitutional symptoms, fever, and arthropathy developed in a 65-year-old patient after cold exposure. Involvement of other family members occurred in an autosomal dominant pattern. Histopathologic examination of a biopsy specimen revealed telangiectasia and primarily neutrophilic perivascular inflammation, consistent with earlier biopsy reports of this syndrome. Although previously called "familial cold urticaria," this disease is not characterized by urticaria and may be best descriptively termed, "familial polymorphous cold eruption."

  3. 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

  4. 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

  5. Creeping eruption

    MedlinePlus

    ... eruption is more common in countries with warm climates. In the United States, the Southeast has the ... MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department ...

  6. Accelerated tooth eruption in children with diabetes mellitus.

    PubMed

    Lal, Shantanu; Cheng, Bin; Kaplan, Selma; Softness, Barney; Greenberg, Ellen; Goland, Robin S; Lalla, Evanthia; Lamster, Ira B

    2008-05-01

    The objective of this study was to evaluate tooth eruption in 6- to 14-year-old children with diabetes mellitus. Tooth eruption status was assessed for 270 children with diabetes and 320 control children without diabetes. Data on important diabetes-related variables were collected. Analyses were performed using logistic regression models. Children with diabetes exhibited accelerated tooth eruption in the late mixed dentition period (10-14 years of age) compared to healthy children. For both case patients and control subjects the odds of a tooth being in an advanced eruptive stage were significantly higher among girls than boys. There was also a trend associating gingival inflammation with expedited tooth eruption in both groups. No association was found between the odds of a tooth being in an advanced stage of eruption and hemoglobin A(1c) or duration of diabetes. Patients with higher body mass index percentile demonstrated statistically higher odds for accelerated tooth eruption, but the association was not clinically significant. Children with diabetes exhibit accelerated tooth eruption. Future studies need to ascertain the role of such aberrations in dental development and complications such as malocclusion, impaired oral hygiene, and periodontal disease. The standards of care for children with diabetes should include screening and referral programs aimed at oral health promotion and disease prevention.

  7. The 2006-2009 activity of the Ubinas volcano (Peru): Petrology of the 2006 eruptive products and insights into genesis of andesite magmas, magma recharge and plumbing system

    NASA Astrophysics Data System (ADS)

    Rivera, Marco; Thouret, Jean-Claude; Samaniego, Pablo; Le Pennec, Jean-Luc

    2014-01-01

    Following a fumarolic episode that started six months earlier, the most recent eruptive activity of the Ubinas volcano (south Peru) began on 27 March 2006, intensified between April and October 2006 and slowly declined until December 2009. The chronology of the explosive episode and the extent and composition of the erupted material are documented with an emphasis on ballistic ejecta. A petrological study of the juvenile products allows us to infer the magmatic processes related to the 2006-2009 eruptions of the andesitic Ubinas volcano. The juvenile magma erupted during the 2006 activity shows a homogeneous bulk-rock andesitic composition (56.7-57.6 wt.% SiO2), which belongs to a medium- to high-K calc-alkaline series. The mineral assemblage of the ballistic blocks and tephra consists of plagioclase > two-pyroxenes > Fe-Ti oxide and rare olivine and amphibole set in a groundmass of the same minerals with a dacitic composition (66-67 wt.% SiO2). Thermo-barometric data, based on two-pyroxene and amphibole stability, records a magma temperature of 998 ± 14 °C and a pressure of 476 ± 36 MPa. Widespread mineralogical and textural features point to a disequilibrium process in the erupted andesite magma. These features include inversely zoned "sieve textures" in plagioclase, inversely zoned clinopyroxene, and olivine crystals with reaction and thin overgrowth rims. They indicate that the pre-eruptive magmatic processes were dominated by recharge of a hotter mafic magma into a shallow reservoir, where magma mingling occurred and triggered the eruption. Prior to 2006, a probable recharge of a mafic magma produced strong convection and partial homogenization in the reservoir, as well as a pressure increase and higher magma ascent rate after four years of fumarolic activity. Mafic magmas do not prevail in the Ubinas pre-historical lavas and tephras. However, mafic andesites have been erupted during historical times (e.g. AD 1667 and 2006-2009 vulcanian eruptions). Hence

  8. The fascinating and complex dynamics of geyser eruptions

    USGS Publications Warehouse

    Hurwitz, Shaul; Manga, Michael

    2017-01-01

    Geysers episodically erupt liquid and vapor. Despite two centuries of scientific study, basic questions persist—why do geysers exist? What determines eruption intervals, durations, and heights? What initiates eruptions? Through monitoring eruption intervals, analyzing geophysical data, taking measurements within geyser conduits, performing numerical simulations, and constructing laboratory models, some of these questions have been addressed. Geysers are uncommon because they require a combination of abundant water recharge, magmatism, and rhyolite flows to supply heat and silica, and large fractures and cavities overlain by low-permeability materials to trap rising multiphase and multicomponent fluids. Eruptions are driven by the conversion of thermal to kinetic energy during decompression. Larger and deeper cavities permit larger eruptions and promote regularity by isolating water from weather variations. The ejection velocity may be limited by the speed of sound of the liquid + vapor mixture.

  9. Assessing the atmospheric and climatic effects of basaltic fissure eruptions. A case study Nornahraun, North Iceland, 2014-2015.

    NASA Astrophysics Data System (ADS)

    Gallagher, Catherine; Burton, Kevin; Thordarson, Thorvaldur; Vye-Brown, Charlotte; Brown, Richard

    2015-04-01

    A volcanic eruption's ability to release sulphur gases into the atmosphere is one of the critical factors in assessing their climatic and environmental effects, because it is directly linked to the potential H2SO4 aerosol burden produced [1]. Basaltic fissure eruptions loft large amounts of sulphur into the atmosphere because of the efficient degassing of volatiles and halogens from the magma at the vent [2-4] coupled with the high sulphur yield of basaltic magma. The common nature of this style of eruption and its products, regardless of magnitude, means that our understanding of the exact processes which influence atmospheric chemistry and environmental impact is very important. The Nornahraun fissure eruption in North Iceland that began on the 31st August 2014, has quickly become one of the best documented eruptions of its kind, through systematic monitoring and sampling by the Institute of Earth Sciences eruption team and The Icelandic Meteorological Office. As a result it is an excellent modern analogue for historic or ancient basaltic fissure eruptions, for which the amount of degassing can only be estimated through petrological and geochemical methods. It also serves as a timely testing platform for novel geochemical proxies. This study uses the exceptional sensitivity of the 187Os-187Re radiogenic system to the presence of crustal material [5], and highly siderophile stable isotopes Cu, Zn and S to indicate the chemistry and degassing of the melt carrying S to the surface. The geochemical isotopic proxies will be tested using established petrological methods and gas emission data. This study concentrates on determining the following key parameters: (1) The source of volatiles in the magma indicated though the pressure dependence of S solubility. (2) The mechanism of aerosol and gas release into the atmosphere is dictated both by the chemistry of the melt that controls the S species (H2S, SO2 or FeS2) present [6], and by the mechanism of transfer. (3) The

  10. Late Holocene Andesitic Eruptions at Mount Rainier

    NASA Astrophysics Data System (ADS)

    Sisson, T. W.; Vallance, J. W.

    2005-12-01

    Holocene Mt. Rainier erupted much more frequently than is recorded by its 11 pumiceous tephras. In the 2.6-2.2 ka Summerland eruptive period, 6 groups of thin (1-5 mm) Sparsely Vesicular Glassy (SVG) ashes were deposited (S1-S6), followed by the 0.3 km3 C-tephra. Two groups of andesitic lava flows and one andesitic block-and-ash flow (2.45 ka) also erupted in the Summerland period (ice conceals any other products). Based on glass composition the pyroclastic flow correlates with S4 ashes that also contain pumiceous grains and rare pumice lapilli. The first of the lava groups, exposed in windows through the Emmons and Winthrop glaciers, is Sr-rich for Mt. Rainier eruptives and correlates with S5 & S6 ashes based on similar high-Sr plagioclase. The ensuing C-tephra formed by plinian eruption of mixed and mingled magma comprising 4 juvenile components: mixed porphyritic andesite pumice, crystal-poor andesite scoria, vesicular high-Sr dacite blebs in pumice and scoria, and poorly inflated crystal-rich high-Sr dacite. High-Sr components were probably entrained conduit linings and segregations from the preceding high-Sr eruptions. The youngest lava group, exposed at the summit, is normal-Sr andesite lacking mixing textures of the C-tephra, and represents eruption of another small batch of andesitic magma perhaps just after the C event. SVG ash grains have blocky-to-fluidal shapes, are rich in plagioclase microlites, and their glasses are high-SiO2 (66-78%) and low-Al2O3 (15-11%). Melting experiments yield apparent equilibration pressures <50MPa for SVG liquids. SVG ashes likely result from shallow hydromagmatic explosions as largely degassed magmas transited the upper-edifice hydrothermal system during effusive eruptions. Rare pumice lapilli codeposited with S1, S2, and S4 ashes have microlite-free dacitic glasses, one with nonreacted hbl phenocrysts. These pumice formed from magmas that ascended rapidly from reservoir depths, synchronous with or closely between effusive

  11. The onset of an eruption: selective assimilation of hydrothermal minerals during pre-eruptive magma ascent of the 2010 summit eruption of Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Pistolesi, M.; Cioni, R.; Francalanci, L.; Bertagnini, A.; D'Oriano, C.; Braschi, E.; Höskuldsson, A.

    2016-11-01

    The complex processes occurring in the initial phases of an eruption are often recorded in the products of its opening stage, which are usually characterized by small volume and limited dispersal, and thus generally poorly studied. The 2010 eruption of Eyjafjallajökull (Iceland) represents a unique opportunity for these investigations thanks to the good preservation of tephra deposits within the ice/snow pack. A detailed geochemical investigation on the glassy groundmass of single ash clasts disclosed a population of fragments with unusual high 87Sr/86Sr (up to 0.70668) for Icelandic magmatism, and anomalous elemental composition with respect to most of the juvenile material of the eruption. This suggests that during its rise, before intruding into the ice cover, magma at a dyke tip selectively assimilated hydrothermal minerals with seawater-related, high-Sr isotopic ratios (zeolites, silica phases, anhydrite) hosted in altered volcanic/epiclastic rocks. According to the observed precursory seismicity, only restricted to few hours before the onset of the eruption, this process could have accompanied subcritical aseismic fracture opening during the days before the eruption, possibly related to stress corrosion-cracking processes, which enhanced the partial dissolution/melting and subsequent selective assimilation of the host rocks.

  12. An Integrative Approach for Defining Plinian and Sub-Plinian Eruptive Scenarios at Andesitic Volcanoes: Event-Lithostratigraphy, Eruptive Parameters and Pyroclast Textural Variations of the Largest Late-Holocene Eruptions of Mt. Taranaki, New Zealand.

    NASA Astrophysics Data System (ADS)

    Torres-Orozco, R.; Cronin, S. J.; Damaschke, M.; Kosik, S.; Pardo, N.

    2016-12-01

    Three eruptive scenarios were determined based on the event-lithostratigraphic reconstruction of the largest late-Holocene eruptions of the andesitic Mt. Taranaki, New Zealand: a) sustained dome-effusion followed by sudden stepwise collapse and unroofing of gas-rich magma; b) repeated plug and burst events generated by transient open-/closed-vent conditions; and c) open-vent conditions of more mafic magmas erupting from a satellite vent. Pyroclastic density currents (PDCs) are the most frequent outcome in every scenario. They can be produced in any/every eruption phase by formation and either repetitive-partial or total gravity-driven collapse of lava domes in the summit crater (block-and-ash flows), frequently followed by sudden magma decompression and violent, highly unsteady to quasi-steady lateral expansion (blast-like PDCs); by collapse or single-pulse fall-back of unsteady eruption columns (pyroclastic flow- and surge-type currents); or during highly unsteady and explosive hydromagmatic phases (wet surges). Fall deposits are produced during the climatic phase of each eruptive scenario by the emplacement of (i) high, sustained and steady, (ii) sustained and height-oscillating, (iii) quasi-steady and pulsating, or (iv) unsteady and totally collapsing eruption columns. Volumes, column heights and mass- and volume-eruption rates indicate that these scenarios correspond to VEI 4-5 plinian and sub-plinian multi-phase and style-shifting episodes, similar or larger than the most recent 1655 AD activity, and comparable to plinian eruptions of e.g. Apoyeque, Colima, Merapi and Tarawera volcanoes. Whole-rock chemistry, textural reconstructions and density-porosity determinations suggest that the different eruptive scenarios are mainly driven by variations in the density structure of magma in the upper conduit. Assuming a simple single conduit model, the style transitions can be explained by differing proportions of alternating gas-poor/degassed and gas-rich magma.

  13. A space-borne, multi-parameter, Virtual Volcano Observatory for the real-time, anywhere-anytime support to decision-making during eruptive crises

    NASA Astrophysics Data System (ADS)

    Ferrucci, F.; Tampellini, M.; Loughlin, S. C.; Tait, S.; Theys, N.; Valks, P.; Hirn, B.

    2013-12-01

    The EVOSS consortium of academic, industrial and institutional partners in Europe and Africa, has created a satellite-based volcano observatory, designed to support crisis management within the Global Monitoring for Environment and Security (GMES) framework of the European Commission. Data from 8 different payloads orbiting on 14 satellite platforms (SEVIRI on-board MSG-1, -2 and -3, MODIS on-board Terra and Aqua, GOME-2 and IASI onboard MetOp-A, OMI on-board Aura, Cosmo-SkyMED/1, /2, /3 and /4, JAMI on-board MTSAT-1 and -2, and, until April 8th2012, SCHIAMACHY on-board ENVISAT) acquired at 5 different down-link stations, are disseminated to and automatically processed at 6 locations in 4 countries. The results are sent, in four separate geographic data streams (high-temperature thermal anomalies, volcanic Sulfur dioxide daily fluxes, volcanic ash and ground deformation), to a central facility called VVO, the 'Virtual Volcano Observatory'. This system operates 24H/24-7D/7 since September 2011 on all volcanoes in Europe, Africa, the Lesser Antilles, and the oceans around them, and during this interval has detected, measured and monitored all subaerial eruptions occurred in this region (44 over 45 certified, with overall detection and processing efficiency of ~97%). EVOSS borne realtime information is delivered to a group of 14 qualified end users, bearing the direct or indirect responsibility of monitoring and managing volcano emergencies, and of advising governments in Comoros, DR Congo, Djibouti, Ethiopia, Montserrat, Uganda, Tanzania, France and Iceland. We present the full set of eruptions detected and monitored - from 2004 to present - by multispectral payloads SEVIRI onboard the geostationary platforms of the MSG constellation, for developing and fine tuning-up the EVOSS system along with its real-time, pre- and post-processing automated algorithms. The set includes 91% of subaerial eruptions occurred at 15 volcanoes (Piton de la Fournaise, Karthala, Jebel al

  14. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2001-01-01

    An Expedition Two crewmember 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. 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.

  15. Failed magmatic eruptions: Late-stage cessation of magma ascent

    USGS Publications Warehouse

    Moran, S.C.; Newhall, C.; Roman, D.C.

    2011-01-01

    When a volcano becomes restless, a primary question is whether the unrest will lead to an eruption. Here we recognize four possible outcomes of a magmatic intrusion: "deep intrusion", "shallow intrusion", "sluggish/viscous magmatic eruption", and "rapid, often explosive magmatic eruption". We define "failed eruptions" as instances in which magma reaches but does not pass the "shallow intrusion" stage, i. e., when magma gets close to, but does not reach, the surface. Competing factors act to promote or hinder the eventual eruption of a magma intrusion. Fresh intrusion from depth, high magma gas content, rapid ascent rates that leave little time for enroute degassing, opening of pathways, and sudden decompression near the surface all act to promote eruption, whereas decreased magma supply from depth, slow ascent, significant enroute degassing and associated increases in viscosity, and impingement on structural barriers all act to hinder eruption. All of these factors interact in complex ways with variable results, but often cause magma to stall at some depth before reaching the surface. Although certain precursory phenomena, such as rapidly escalating seismic swarms or rates of degassing or deformation, are good indicators that an eruption is likely, such phenomena have also been observed in association with intrusions that have ultimately failed to erupt. A perpetual difficulty with quantifying the probability of eruption is a lack of data, particularly on instances of failed eruptions. This difficulty is being addressed in part through the WOVOdat database. Papers in this volume will be an additional resource for scientists grappling with the issue of whether or not an episode of unrest will lead to a magmatic eruption.

  16. High-resolution Observations of Sympathetic Filament Eruptions by NVST

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Shangwei; Su, Yingna; Zhou, Tuanhui

    We investigate two sympathetic filament eruptions observed by the New Vacuum Solar Telescope on 2015 October 15. The full picture of the eruptions is obtained from the corresponding Solar Dynamics Observatory ( SDO )/Atmospheric Imaging Assembly (AIA) observations. The two filaments start from active region NOAA 12434 in the north and end in one large quiescent filament channel in the south. The left filament erupts first, followed by the right filament eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both filaments during the eruption. Both eruptions failed, since the filaments first rise up, thenmore » flow toward the south and merge into the southern large quiescent filament. We also observe repeated activations of mini filaments below the right filament after its eruption. Using magnetic field models constructed based on SDO /HMI magnetograms via the flux rope insertion method, we find that the left filament eruption is likely to be triggered by kink instability, while the weakening of overlying magnetic fields due to magnetic reconnection at an X-point between the two filament systems might play an important role in the onset of the right filament eruption.« less

  17. Study New Pregress on Volcanic Phreatomagmatic Eruption

    NASA Astrophysics Data System (ADS)

    Sun, Q.; Fan, Q.; Li, N.

    2007-12-01

    As an essential and important type of volcanic eruption on earth, phreatomagmatic eruption is characterized by groundwater-related explosive eruption and subsequent base surge deposit and maar lakes. Base surge deposit and maar lakes are widely distributed all over the world, and also in the Northeast China and the southern China. Study of phreatomagmatic eruption maybe dated back to 1921, and in the following over 80 years, many works have been done on phreatomagmatic eruption, using various of methods of volcanic geology, petrology, sedimentology, physical volcanology and digital modeling, to discuss its origin and mechanism. In this paper, we focus on the geological feature of the base surge deposit and dynamic mechanism of the phreatomagmatic eruption. When ascending basaltic magma meets with ground ( surface ) water, violent explosion would occur, this action was called phreatomagmatic eruption. The main product of this kind of eruption are maars and base surge. As to the base surge, it has long been treated as sedimentary tuff by mistake. Usually, base surge is distributed around maar, different from the distribution of sedimentary tuff. Typical phenomena of base surge caused by phreatomagmatic eruption can be observed through the detail field work, such as large-scale and low-angle cross-bedding, slaty-bedding, current-bedding and distal facies accretionary lapilli. In order to explain the dynamic mechanism of phreatomagmatic eruption thoroughly, we propose a simple model in this paper in light of the elasticity theory. Some conclusions can be drawn as follows: the larger the radius of maar, the larger the explosive wallop needed for the formation of maar is; provided that the radius of maar and depth of explosive point are limited, then the larger the area of contact surface between magma and groundwater, the stronger the explosive energy will be; if the explosive energy and area of explosive point are restricted, the larger the radius of maar, the greater

  18. 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

    Scoria cone eruptions are generally modeled as a simple succession from explosive eruption to form the cone to passive effusion of lava, generally from the base of the cone. Sector collapse of scoria cones, wherein parts of the cone are rafted on a lava flow, is increasingly recognized as common, but the reasons that a cone may not be rebuilt are poorly understood. Red Mountain volcano is a Pleistocene scoria cone in the San Francisco Volcanic Field of northern Arizona, USA. The cone lies along the trace of a major steeply dipping normal fault that originated during Proterozoic tectonism and was reactivated in Tertiary time. The earliest phase of eruption at Red Mountain was typical "Strombolian", forming a cone that was followed by or possibly synchronous with lava effusion, toward the west from the base of the cone. Rafting then ensued as the west side of the cone collapsed; approximately 15% of the cone is preserved in mounds as much as 30 m high. Rafting was extensive enough to remove most of the cone over the vent area, which effectively reduced the pressure cap on the magma conduit. Resultant low fountaining fed clastogenic lava flows and minor scoria fallback. Clastogenic flows traveled as far as 4 km and now form a cliff 30-40 m high at the edge of the lava platform. Although several possibilities explain the change in vent dynamics and eruptive style, we favor the interpretation that an increase in magma-rise rate caused collapse of the cone. The abrupt removal of 300 m of material over the vent removed a conduit "cork" and low fountaining began. Magma that had erupted effusively suddenly became explosive. This aspect of scoria cone rafting at Red Mountain is broadly similar to sector collapse followed by explosive eruption in larger systems. A steep-walled, 150-m-high amphitheatre on the northeast side of Red Mountain exposes weakly to strongly altered scoria cemented by calcite, iron, and zeolites. We suggest that vapor-phase alteration was responsible

  19. Are flood basalt eruptions monogenetic or polygenetic?

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Cañón-Tapia, Edgardo

    2015-11-01

    A fundamental classification of volcanoes divides them into "monogenetic" and "polygenetic." We discuss whether flood basalt fields, the largest volcanic provinces, are monogenetic or polygenetic. A polygenetic volcano, whether a shield volcano or a stratovolcano, erupts from the same dominant conduit for millions of years (excepting volumetrically small flank eruptions). A flood basalt province, built from different eruptive fissures dispersed over wide areas, can be considered a polygenetic volcano without any dominant vent. However, in the same characteristic, a flood basalt province resembles a monogenetic volcanic field, with only the difference that individual eruptions in the latter are much smaller. This leads to the question how a flood basalt province can be two very different phenomena at the same time. Individual flood basalt eruptions have previously been considered monogenetic, contrasted by only their high magma output (and lava fluidity) with typical "small-volume monogenetic" volcanoes. Field data from Hawaiian shield volcanoes, Iceland, and the Deccan Traps show that whereas many feeder dykes were single magma injections, and the eruptions can be considered "large monogenetic" eruptions, multiple dykes are equally abundant. They indicate that the same dyke fissure repeatedly transported separate magma batches, feeding an eruption which was thus polygenetic by even the restricted definition (the same magma conduit). This recognition helps in understanding the volcanological, stratigraphic, and geochemical complexity of flood basalts. The need for clear concepts and terminology is, however, strong. We give reasons for replacing "monogenetic volcanic fields" with "diffuse volcanic fields" and for dropping the term "polygenetic" and describing such volcanoes simply and specifically as "shield volcanoes," "stratovolcanoes," and "flood basalt fields."

  20. Seismicity of the Earth 1900-2013 East African Rift

    USGS Publications Warehouse

    Hayes, Gavin P.; Jones, Eric S.; Stadler, Timothy J.; Barnhart, William D.; McNamara, Daniel E.; Benz, Harley M.; Furlong, Kevin P.; Villaseñor, Antonio; Hayes, Gavin P.; Jones, Eric S.; Stadler, Timothy J.; Barnhart, William D.; McNamara, Daniel E.; Benz, Harley M.; Furlong, Kevin P.; Villaseñor, Antonio

    2014-01-01

    Rifting in East Africa is not all coeval; volcanism and faulting have been an ongoing phenomenon on the continent since the Eocene (~45 Ma). The rifting began in northern East Africa, and led to the separation of the Nubia (Africa) and Arabia plates in the Red Sea and Gulf of Aden, and in the Lake Turkana area at the Kenya-Ethiopia border. A Paleogene mantle superplume beneath East Africa caused extension within the Nubia plate, as well as a first order topographic high known as the African superswell which now includes most of the eastern and southern sectors of the Nubia plate. Widespread volcanism erupted onto much of the rising plateau in Ethiopia during the Eocene-Oligocene (45–29 Ma), with chains of volcanoes forming along the rift separating Africa and Arabia. Since the initiation of rifting in northeastern Africa, the system has propagated over 3,000 km to the south and southwest, and it experiences seismicity as a direct result of the extension and active magmatism.

  1. Eruptions at Lone Star Geyser, Yellowstone National Park, USA, part 1: energetics and eruption dynamics

    USGS Publications Warehouse

    Karlstrom, Leif; Hurwitz, Shaul; Sohn, Robert; Vandemeulebrouck, Jean; Murphy, Fred; Rudolph, Maxwell L.; Johnston, Malcolm J.S.; Manga, Michael; McCleskey, R. Blaine

    2013-01-01

    Geysers provide a natural laboratory to study multiphase eruptive processes. We present results from a four–day experiment at Lone Star Geyser in Yellowstone National Park, USA. We simultaneously measured water discharge, acoustic emissions, infraredintensity, and visible and infrared video to quantify the energetics and dynamics of eruptions, occurring approximately every three hours. We define four phases in the eruption cycle: 1) a 28 ± 3 minute phase with liquid and steam fountaining, with maximum jet velocities of 16–28 m s− 1, steam mass fraction of less than ∼ 0.01. Intermittently choked flow and flow oscillations with periods increasing from 20 to 40 s are coincident with a decrease in jet velocity and an increase of steam fraction; 2) a 26 ± 8 minute post–eruption relaxation phase with no discharge from the vent, infrared (IR) and acoustic power oscillations gliding between 30 and 40 s; 3) a 59 ± 13 minute recharge period during which the geyser is quiescent and progressively refills, and 4) a 69 ± 14 minute pre–play period characterized by a series of 5–10 minute–long pulses of steam, small volumes of liquid water discharge and 50–70 s flow oscillations. The erupted waters ascend froma 160 − 170° C reservoir and the volume discharged during the entire eruptive cycle is 20.8 ± 4.1 m3. Assuming isentropic expansion, we calculate a heat output from the geyser of 1.4–1.5 MW, which is < 0.1% of the total heat output from Yellowstone Caldera.

  2. Eruptive and Transportation Processes During Caldera-Forming Eruptions of Sete Cidades Volcano, São Miguel, Azores

    NASA Astrophysics Data System (ADS)

    Kueppers, U.; Queiroz, M. G.; Pacheco, J. M.

    2007-12-01

    Sete Cidades volcano forms the Western part of the island of São Miguel, Azores, which is hosting three active trachytic central volcanoes (Sete Cidades, Fogo, Furnas). Volcanic activity in the archipelago exhibits a strong tectonic control and on São Miguel, the NW-SE trending basaltic Terceira Rift is intersecting the central volcanoes. All three have erupted since the settlement of the island in the 15{th} century. The Eastern part of the island is considered extinct. The oldest dated subaerial rocks of Sete Cidades exhibit an age of 210 ka. Morphology of the present summit caldera (5 km diameter, up to 350 m deep), stratigraphy, and distribution of the deposits suggest a multiple-stage evolution and at least three caldera-forming eruptions (CFE) are assumed to have occurred. 14C-dating revealed ages of 36, 29, and 16 ka, respectively, for the most recent ones. Today, the average slope angle is 12° and the maximum distance of the coastline from the caldera rim approx. 5 km. Assuming a comparable situation at the time of the CFE, a large portion of the eruptive products has probably not been deposited on land. After a pause of several thousand years, eruptive activity resumed approx. 5 ka ago and started filling the caldera. As deposits of minor thickness and distribution can be found between the deposits of the CFE, it is unclear whether the caldera formation is completely finished. Climatic factors (e.g. precipitation, air humidity) have affected the deposits by erosion, weathering, and possibly significant reworking and caused dense vegetation on all flanks of the volcano. Still, it was possible to establish distribution and thickness of the deposits of the CFE and constrain differences in eruptive behaviour and transport/emplacement mechanisms. They are composed of air-fall deposits and pyroclastic density currents but show significant differences amongst them: (1) Degree of pre- and syn-eruptive magma-magma interaction and syn-eruptive magma

  3. How We Began - About the Guard - The National Guard

    Science.gov Websites

    Partnership Program Special Features Your National Guard About the Guard How We Began Air National Guard Army National Guard About Us By the Numbers Contact Us FAQ Federal Mission History Join Us Leaders Director of the ARNG Deputy Director of the ARNG Chief of Staff of the ARNG Command Chief Warrant Officer of the

  4. Stereoscopic Analysis of 19 May and 31 Aug 2007 Filament Eruptions

    NASA Technical Reports Server (NTRS)

    Liewer, Paulett; DeJong, E. M.; Hall, J. R.

    2008-01-01

    The presentation outline includes results from stereoscopic analysis of SECCHI/EUVI data for 19 May 2007 filament eruption, including the determined 3D trajectory of erupting filament, strong evidence for reconnection below erupting filament as consistent with standard model, and comparison of EUVI and H-alpha images during eruption; and results from stereoscopic analytic of 21 August 2007 filament eruption. Slide topics include standard model of filament eruption; 2007 May 19 STEREO A/SECCHI/EUVI 195 and 304 A: CME signatures and filament eruption, 3D reconstruction of erupting prominence; filament's relation to coronal magnetic fields; 3d reconstructions of filament eruption; height-time plot of eruption from 3D reconstructions; detailed pre-eruptions comparison of H-alpha and EUVI 304 at 12:42 UT; comparisons during the eruption; STEREO prominence and CME August 31, 2007; reconstructions of prominence and leading edges of both dark cavity and CME; and 3D reconstructions of prominence and leading edges.

  5. Mafic enclaves record syn-eruptive basalt intrusion and mixing

    NASA Astrophysics Data System (ADS)

    Plail, Melissa; Edmonds, Marie; Woods, Andrew W.; Barclay, Jenni; Humphreys, Madeleine C. S.; Herd, Richard A.; Christopher, Thomas

    2018-02-01

    Mafic enclaves hosted by andesite erupted at the Soufrière Hills Volcano between 1995 and 2010 yield insights into syn-eruptive mafic underplating of an andesite magma reservoir, magma mixing and its role in sustaining eruptions that may be widely applicable in volcanic arc settings. The mafic enclaves range in composition from basalt to andesite and are generated from a hybrid thermal boundary layer at the interface between the two magmas, where the basalt quenches against the cooler andesite, and the two magmas mix. We show, using an analytical model, that the enclaves are generated when the hybrid layer, just a few tens of centimetres thick, becomes buoyant and forms plumes which rise up into the andesite. Mafic enclave geochemistry suggests that vapour-saturated basalt was underplated quasi-continuously throughout the first three eruptive phases of the eruption (the end member basalt became more Mg and V-rich over time). The andesite erupted during the final phases of the eruption contained more abundant and larger enclaves, and the enclaves were more extensively hybridised with the andesite, suggesting that at some time during the final few years of the eruption, the intrusion of mafic magma at depth ceased, allowing the hybrid layer to reach a greater thickness, generating larger mafic enclaves. The temporal trends in mafic enclave composition and abundance suggests that basalt recharge and underplating sustained the eruption by the transfer of heat and volatiles across the interface and when the recharge ceased, the eruption waned. Our study has important implications for the petrological monitoring of long-lived arc eruptions.

  6. 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

  7. 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

  8. Particle transport in subaqueous eruptions: An experimental investigation

    NASA Astrophysics Data System (ADS)

    Verolino, A.; White, J. D. L.; Zimanowski, B.

    2018-01-01

    Subaqueous volcanic eruptions are natural events common under the world's oceans. Here we report results from bench-scale underwater explosions that entrain and eject particles into a water tank. Our aim was to examine how particles are transferred to the water column and begin to sediment from it, and to visualize and interpret evolution of the 'eruption' cloud. Understanding particle transfer to water is a key requirement for using deposit characteristics to infer behaviour and evolution of an underwater eruption. For the experiments here, we used compressed argon to force different types of particles, under known driving pressures, into water within a container, and recorded the results at 1 MPx/frame and 1000 fps. Three types of runs were completed: (1) particles within water were driven into a water-filled container; (2) dry particles were driven into water; (3) dry particles were driven into air at atmospheric pressure. Across the range of particles used for all subaqueous runs, we observed: a) initial doming, b) a main expansion of decompressing gas, and c) a phase of necking, when a forced plume separated from the driving jet. Phase c did not take place for the subaerial runs. A key observation is that none of the subaqueous explosions produced a single, simple, open cavity; in all cases, multiphase mixtures of gas bubbles, particles and water were formed. Explosions in which the expanding argon ejects particles in air, analogous to delivery of particles created in an explosion, produce jets and forced plumes that release particles into the tank more readily than do those in which particles in water are driven into the tank. The latter runs mimic propulsion of an existing vent slurry by an explosion. Explosions with different particle types also yielded differences in behaviour controlled primarily by particle mass, particle density, and particle-population homogeneity. Particles were quickly delivered into the water column during plume rise following

  9. Solar Eruptive Flares: from Physical Understanding to Probabilistic Forecasting

    NASA Astrophysics Data System (ADS)

    Georgoulis, M. K.

    2013-12-01

    We describe a new, emerging physical picture of the triggering of major solar eruptions. First, we discuss and aim to interpret the single distinguishing feature of tight, shear-ridden magnetic polarity inversion lines (PILs) in solar active regions, where most of these eruptions occur. Then we analyze the repercussions of this feature, that acts to form increasingly helical pre-eruption structures. Eruptions, with the CME progenitor preceding the flare, tend to release parts of the accumulated magnetic free energy and helicity that are always much smaller than the respective budgets of the source active region. These eruption-related decreases, however, are not optimal for eruption forecasting - this role is claimed by physically intuitive proxy parameters that could show increased pre-eruption sensitivity at time scales practical for prediction. Concluding, we show how reconciling this new information - jointly enabled by the exceptional resolution and quality of Hinode and cadence of SDO data - can lead to advances in understanding that outline the current state-of-the-art of our eruption-forecasting capability.

  10. Eruptive history of Mount Mazama and Crater Lake Caldera, Cascade Range, U.S.A.

    USGS Publications Warehouse

    Bacon, C.R.

    1983-01-01

    silicic lavas commonly contain traces of hornblende and record early stages in the development of the climatic magma chamber. Some 15,000 to 40,000 yr were apparently needed for development of the climactic magma chamber, which had begun to leak rhyodacitic magma by 7015 ?? 45 yr B.P. Four rhyodacitic lava flows and associated tephras were emplaced from an arcuate array of vents north of the summit of Mount Mazama, during a period of ??? 200 yr before the climactic eruption. The climactic eruption began 6845 ?? 50 yr B.P. with voluminous airfall deposition from a high column, perhaps because ejection of ??? 4-12 km3 of magma to form the lava flows and tephras depressurized the top of the system to the point where vesiculation at depth could sustain a Plinian column. Ejecta of this phase issued from a single vent north of the main Mazama edifice but within the area in which the caldera later formed. The Wineglass Welded Tuff of Williams (1942) is the proximal featheredge of thicker ash-flow deposits downslope to the north, northeast, and east of Mount Mazama and was deposited during the single-vent phase, after collapse of the high column, by ash flows that followed topographic depressions. Approximately 30 km3 of rhyodacitic magma were expelled before collapse of the roof of the magma chamber and inception of caldera formation ended the single-vent phase. Ash flows of the ensuing ring-vent phase erupted from multiple vents as the caldera collapsed. These ash flows surmounted virtually all topographic barriers, caused significant erosion, and produced voluminous deposits zoned from rhyodacite to mafic andesite. The entire climactic eruption and caldera formation were over before the youngest rhyodacitic lava flow had cooled completely, because all the climactic deposits are cut by fumaroles that originated within the underlying lava, and part of the flow oozed down the caldera wall. A total of ??? 51-59 km3 of magma was ejected in the precursory and climactic eruptions,

  11. Volatile Abundances and Magma Geochemistry of Recent (2006) Through Ancient Eruptions (Less Than 2100 aBP) of Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Webster, J. D.; Mandeville, C. W.; Gerard, T.; Goldoff, B.; Coombs, M. L.

    2006-12-01

    dikes to depths as shallow as 2.4 to 0.6 km, at which stage the fluid or fluids began to separate from magma. Fluid separation may have generated some of the seismic signals recorded at these depths during pre-2006 volcanic eruptions. We will examine 2006 juvenile material to evaluate whether or not similar processes of magma evolution and ascent were operative. Johnston D.A. (1978) Univ. Washington unpub. Ph.D. dissertation. Roman, D.C., et al. (2005) Bull. Volcanol. 84:240-254.

  12. Emplacement of the final lava dome of the 2009 eruption of Redoubt Volcano, Alaska

    USGS Publications Warehouse

    Bull, Katharine F.; Anderson, Steven W.; Diefenbach, Angela K.; Wessels, Rick L.; Henton, Sarah M.

    2013-01-01

    After more than 8 months of precursory activity and over 20 explosions in 12 days, Redoubt Volcano, Alaska began to extrude the fourth and final lava dome of the 2009 eruption on April 4. By July 1 the dome had filled the pre-2009 summit crater and ceased to grow. By means of analysis and annotations of time-lapse webcam imagery, oblique-image photogrammetry techniques and capture and analysis of forward-looking infrared (FLIR) images, we tracked the volume, textural, effusive-style and temperature changes in near-real time over the entire growth period of the dome. The first month of growth (April 4–May 4) produced blocky intermediate- to high-silica andesite lava (59–62.3 wt.% SiO2) that initially formed a round dome, expanding by endogenous growth, breaking the surface crust in radial fractures and annealing them with warmer, fresh lava. On or around May 1, more finely fragmented and scoriaceous andesite lava (59.8–62.2 wt.% SiO2) began to appear at the top of the dome coincident with increased seismicity and gas emissions. The more scoriaceous lava spread radially over the dome surface, while the dome continued to expand from endogenous growth and blocky lava was exposed on the margins and south side of the dome. By mid-June the upper scoriaceous lava had covered 36% of the dome surface area. Vesicularity of the upper scoriaceous lava range from 55 to 66%, some of the highest vesicularity measurements recorded from a lava dome.We suggest that the stability of the final lava dome primarily resulted from sufficient fracturing and clearing of the conduit by preceding explosions that allowed efficient degassing of the magma during effusion. The dome was thus able to grow until it was large enough to exceed the magmastatic pressure in the chamber, effectively shutting off the eruption.

  13. The 1989-1990 eruptions of Redoubt Volcano: an introduction

    USGS Publications Warehouse

    Miller, T.P.; Chouet, B.A.

    1994-01-01

    Redoubt Volcano, located on the west side of Cook Inlet in south-central Alaska, erupted explosively on over 20 separate occasions between December 14, 1989 and April 21, 1990. Fourteen lava domes were emplaced in the summit area, thirteen of which were subsequently destroyed. The eruption caused economic losses estimated at over $160,000,000 making this the second most costly eruption in U.S. history. This economic impact provided the impetus for a integrated comprehensive account of an erupting volcano using both modern and classical research and modern techniques which in turn led to advances in eruption monitoring and interpretation. Research on such topics as dome formation and collapse and the resulting pyroclastic flows, elutriated ash, lightning, tephra, and flooding was blended with the rapid communication of associated hazards to a large user group. The seismology successes in predicting and monitoring eruption dynamics were due in part to (1) the recognition of long-period seismic events as indicators of the readiness of the volcano to erupt, and (2) to the development of new tools that allowed the seismicity to be assessed instantaneously. Integrated studies of the petrology of erupted products and volatile content over time gave clues as to the progress of the eruption towards completion. ?? 1994.

  14. Pre-eruptive volatile and erupted gas phase characterization of the 2014 basalt of Bárðarbunga volcanic system, Iceland.

    NASA Astrophysics Data System (ADS)

    Haddadi, Baptiste; Moune, Séverine; Sigmarsson, Olgeir; Gauthier, Pierre-Jean; Gouhier, Mathieu

    2015-04-01

    The 2014 Holuhraun eruption on the Bárðarbunga Volcanic System is the largest fissure eruption in Iceland since the 1783 Laki eruption. The eruption started end of August 2014 and has been characterized by large emission of SO2 into the atmosphere. It provides a rare opportunity to study in details magmatic and degassing processes during a large-volume fissure eruption. In order to characterize the pre-eruptive magmatic composition and to assess the plume chemistry at the eruption site, lava and tephra were sampled together with the eruption plume. The basalt composition is olivine tholeiite with MgO close to 7 wt%. It is phenocryst-poor with plagioclase as the dominant mineral phase but olivine and clinopyroxene are also present together with sulphide globules composed principally of pyrite and chalcopyrite. The volatile (S, Cl and F) and major element concentrations were measured by the electron microprobe in melt inclusions (MIs) trapped in plagioclase and clinopyroxene and groundmass glass. The MIs composition ranges from fairly primitive basaltic compositions (MgO: 9.03 wt%) down to evolved qz-tholeiites (MgO: 5.57 wt%), with estimated pre-eruptive S concentrations of 1500 ppm. Tephra groundmass glass contains 400 ppm S, whereas Cl and F concentrations are respectively slightly lower and indistinguishable from those in the MIs. This implies limited exsolution of halogens but 75% of the initial sulphur content. Relatively to their total iron content, MIs are sulphur saturated, and their oxygen fugacity close to the FMQ buffer. The difference between the estimated initial volatile concentrations measured in the MIs and in the tephra groundmass (i.e. the so-called petrological method) yields 7.2 Mt SO2, limited HCl and no HF atmospheric mass loading from the Holuhraun 2014 eruption. The SO2/HCl molar ratio of the gas phase, calculated from the MIs, is 13 and 14, respectively, using average and estimated pre-eruptive S and Cl concentrations in the MIs. Filter

  15. A Comparative Study of the Eruptive and Non-eruptive Flares Produced by the Largest Active Region of Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Sarkar, Ranadeep; Srivastava, Nandita

    2018-02-01

    We investigate the morphological and magnetic characteristics of solar active region (AR) NOAA 12192. AR 12192 was the largest region of Solar Cycle 24; it underwent noticeable growth and produced 6 X-class flares, 22 M-class flares, and 53 C-class flares in the course of its disc passage. However, the most peculiar fact of this AR is that it was associated with only one CME in spite of producing several X-class flares. In this work, we carry out a comparative study between the eruptive and non-eruptive flares produced by AR 12192. We find that the magnitude of abrupt and permanent changes in the horizontal magnetic field and Lorentz force are significantly smaller in the case of the confined flares compared to the eruptive one. We present the areal evolution of AR 12192 during its disc passage. We find the flare-related morphological changes to be weaker during the confined flares, whereas the eruptive flare exhibits a rapid and permanent disappearance of penumbral area away from the magnetic neutral line after the flare. Furthermore, from the extrapolated non-linear force-free magnetic field, we examine the overlying coronal magnetic environment over the eruptive and non-eruptive zones of the AR. We find that the critical decay index for the onset of torus instability was achieved at a lower height over the eruptive flaring region, than for the non-eruptive core area. These results suggest that the decay rate of the gradient of overlying magnetic-field strength may play a decisive role to determine the CME productivity of the AR. In addition, the magnitude of changes in the flare-related magnetic characteristics are found to be well correlated with the nature of solar eruptions.

  16. Understanding the plume dynamics of explosive super-eruptions.

    PubMed

    Costa, Antonio; J Suzuki, Yujiro; Koyaguchi, Takehiro

    2018-02-13

    Explosive super-eruptions can erupt up to thousands of km 3 of magma with extremely high mass flow rates (MFR). The plume dynamics of these super-eruptions are still poorly understood. To understand the processes operating in these plumes we used a fluid-dynamical model to simulate what happens at a range of MFR, from values generating intense Plinian columns, as did the 1991 Pinatubo eruption, to upper end-members resulting in co-ignimbrite plumes like Toba super-eruption. Here, we show that simple extrapolations of integral models for Plinian columns to those of super-eruption plumes are not valid and their dynamics diverge from current ideas of how volcanic plumes operate. The different regimes of air entrainment lead to different shaped plumes. For the upper end-members can generate local up-lifts above the main plume (over-plumes). These over-plumes can extend up to the mesosphere. Injecting volatiles into such heights would amplify their impact on Earth climate and ecosystems.

  17. Volcanic crystals as time capsules of eruption history.

    PubMed

    Ubide, Teresa; Kamber, Balz S

    2018-01-23

    Crystals formed prior to a volcanic event can provide evidence of processes leading to and timing of eruptions. Clinopyroxene is common in basaltic to intermediate volcanoes, however, its ability as a recorder of pre-eruptive histories has remained comparatively underexplored. Here we show that novel high-resolution trace element images of clinopyroxene track eruption triggers and timescales at Mount Etna (Sicily, Italy). Chromium (Cr) distribution in clinopyroxene from 1974 to 2014 eruptions reveals punctuated episodes of intrusion of primitive magma at depth. Magma mixing efficiently triggered volcanism (success rate up to 90%), within only 2 weeks of arrival of mafic intrusions. Clinopyroxene zonations distinguish between injections of mafic magma and regular recharges with more evolved magma, which often fail to tip the system to erupt. High Cr zonations can therefore be used to reconstruct past eruptions and inform responses to geophysical signals of volcano unrest, potentially offering an additional approach to volcano hazard monitoring.

  18. Global time-size distribution of volcanic eruptions on Earth.

    PubMed

    Papale, Paolo

    2018-05-01

    Volcanic eruptions differ enormously in their size and impacts, ranging from quiet lava flow effusions along the volcano flanks to colossal events with the potential to affect our entire civilization. Knowledge of the time and size distribution of volcanic eruptions is of obvious relevance for understanding the dynamics and behavior of the Earth system, as well as for defining global volcanic risk. From the analysis of recent global databases of volcanic eruptions extending back to more than 2 million years, I show here that the return times of eruptions with similar magnitude follow an exponential distribution. The associated relative frequency of eruptions with different magnitude displays a power law, scale-invariant distribution over at least six orders of magnitude. These results suggest that similar mechanisms subtend to explosive eruptions from small to colossal, raising concerns on the theoretical possibility to predict the magnitude and impact of impending volcanic eruptions.

  19. Comparative geothermometry of recent Hawaiian eruptions

    NASA Astrophysics Data System (ADS)

    Helz, Rosalind Tuthill; Banks, Norman G.; Heliker, Christina; Neal, Christina A.; Wolfe, Edward W.

    1995-09-01

    In this paper we compare lava temperatures measured using Cr-Al thermocouples or infrared spectrometry with estimated quenching temperatures based on the glass geothermometry calibration of Helz and Thornber (1987). Comparative data are available for the April 1982 and September 1982 summit eruptions, the Pu'u O'o east rift eruption (1983-1986), all three eruptions at Kilauea, and the 1984 Mauna Loa eruption. The results show that quenching temperatures, based on the MgO contents of Kilauean glasses (TMgO), lie within ±10°C of field measurements using the infrared spectrometer for 85% of the samples. Where a Cr-Al thermocouple was used, 90% of the field measurements lie within +1° to -11°C of TMgO for samples with Tfield > 1130°C. Samples where Tfield < 1130°C show larger divergence. The uncertainty in TMgO by itself is ±10°C, so the level of agreement between field measurements and TMgO is very good for Kilauean lavas. Systematic comparison of field measurements of temperature with glass geothermometry for the 1984 Mauna Loa eruption suggests that, although the field and glass temperatures lie within ±10°C of each other, the Kilauean TMgO calibration is nevertheless not appropriate for Mauna Loa glasses and that actual quenching temperatures for Mauna Loa samples will lie 10°-20°C higher than would be predicted from the Kilauea calibration curve. Consideration of possible effects of variable volatile content suggest that in most cases these are small. Samples erupted early in an eruption may reflect preeruptive water contents different enough to affect TMgO significantly, but later spatter samples and all flow samples appear to have equilibrated at low enough water contents for the calibration to be applicable. We conclude that the MgO-based geothermometer can be applied to glassy Kilauean samples to give temperatures that generally will lie within ±10°C of a field measurement. Plots of glass MgO content versus time, if a suitable sample base is

  20. 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

  1. 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

  2. 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

  3. 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.

  4. CHAIN RECONNECTIONS OBSERVED IN SYMPATHETIC ERUPTIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Joshi, Navin Chandra; Magara, Tetsuya; Schmieder, Brigitte

    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 themore » 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.« less

  5. 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.

  6. 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.

  7. Eruption precursors: Manifestations and strategies for detection

    NASA Astrophysics Data System (ADS)

    Poland, Michael; Pritchard, Matthew

    2017-04-01

    The past several decades have seen a rapid increase in volcano monitoring and modeling capabilities. Diverse arrays of instrument networks can detect a variety of pre-, co-, and post-eruptive phenomena, and remote sensing observations are available across a range of spatial, temporal, and spectral resolutions. A growing class of models, based on the physics of magmatic systems, are making use of these expanding datastreams, providing probabilistic assessments of such parameters as magma supply, volatile content, and eruption duration. To what extent, however, do these developments heighten our ability to identify eruption precursors? The advent of better data and new models provides an opportunity to reexamine our understanding of pre-eruption unrest, as well as our ability to detect and recognize it as such. An idealized model of the buildup to a volcanic eruption might include magma ascent from a deep source region and accumulation in the mid- to upper crust in the preceding months to years. The process might be manifested by surface inflation and deep long-period earthquakes, and accompanied by an increase in CO2 emissions. As magma continues to accumulate, distal volcano-tectonic earthquakes may result as stress builds on nearby faults, H2S emissions may increase as sulfur in a shallow reservoir is hydrolyzed by groundwater, and fumarole and spring temperatures may increase and show changes in chemistry. In the days to hours before an eruption, sudden changes in the rate and style of earthquakes (including repeating earthquakes and tremor) and deformation may occur as the magma reservoir ruptures and magma moves laterally or vertically. Phreatic eruptions might result as ascending magma comes into contact with groundwater, and SO2 emissions might increase as the path between the magma and surface dries out. How often does such a sequence actually occur? Relatively few volcanoes are comprehensively monitored prior to obvious expressions of unrest, so this is not

  8. Geochemical and textural constraints on degassing processes in sub-Plinian eruptions: case-study of the Greenish Pumice eruption of Mount Somma-Vesuvius

    NASA Astrophysics Data System (ADS)

    Zdanowicz, G.; Boudon, G.; Balcone-Boissard, H.; Cioni, R.; Mundula, F.; Orsi, G.; Civetta, L.; Agrinier, P.

    2018-04-01

    Plinian eruptions are characterized by high intensity and an overall steady character, and result in a stable convective column. The main processes controlling the dynamics of such steady and stable plume systems have been extensively investigated. Conversely, sub-Plinian eruptions are unsteady, as recorded by the large variability of the products and deposits. Our knowledge of the processes creating this unsteadiness on various timescales remains limited, and still requires more observations as well as theoretical and experimental investigation. Here, we focus on the sub-Plinian eruption of the Greenish Pumice (GP, 19,265 ± 105 BP), Mt. Somma-Vesuvius (Italy). On the basis of coupled geochemical and textural analyses of samples from the well-established stratigraphy of the GP deposits, we investigate volatiles (H2O, CO2, F, Cl) to better constrain the unsteady sub-Plinian eruptive style. This allows us to carry out a detailed study of the degassing processes in relation to the eruption dynamics. We find that degassing by open-system processes generally dominates throughout the entire eruption, but alternates with episodes of closed-system degassing. The fluctuating degassing regimes, responsible for the variable magma ascent rate within the conduit, are also responsible for the eruptive column instability. Volatile behavior is well correlated with textural heterogeneities of the eruptive products. Both reflect higher conduit heterogeneity than for Plinian eruptions, where we find a higher horizontal gradient in magma ascent velocity due to a smaller conduit diameter.

  9. Large historical eruptions at subaerial mud volcanoes, Italy

    NASA Astrophysics Data System (ADS)

    Manga, M.; Bonini, M.

    2012-11-01

    Active mud volcanoes in the northern Apennines, Italy, currently have gentle eruptions. There are, however, historical accounts of violent eruptions and outbursts. Evidence for large past eruptions is also recorded by large decimeter rock clasts preserved in erupted mud. We measured the rheological properties of mud currently being erupted in order to evaluate the conditions needed to transport such large clasts to the surface. The mud is well-characterized by the Herschel-Bulkley model, with yield stresses between 4 and 8 Pa. Yield stresses of this magnitude can support the weight of particles with diameters up to several mm. At present, particles larger than this size are not being carried to the surface. The transport of larger clasts to the surface requires ascent speeds greater than their settling speed in the mud. We use a model for the settling of particles and rheological parameters from laboratory measurements to show that the eruption of large clasts requires ascent velocities > 1 m s-1, at least three orders of magnitude greater than during the present, comparatively quiescent, activity. After regional earthquakes on 20 May and 29 May 2012, discharge also increased at locations where the stress changes produced by the earthquakes would have unclamped feeder dikes below the mud volcanoes. The magnitude of increased discharge, however, is less than that inferred from the large clasts. Both historical accounts and erupted deposits are consistent in recording episodic large eruptions.

  10. Micro-scale δ18O analyses of a Borneo stalagmite across the Toba super-eruption

    NASA Astrophysics Data System (ADS)

    Orland, I. J.; Cobb, K. M.; Carolin, S.; Linzmeier, B.; Valley, J. W.; Adkins, J. F.

    2016-12-01

    The Toba super-eruption occurred in close association with an abrupt climate transition from Greenland Interstadial (GI-) 20 to Greenland Stadial (GS-) 20, roughly 74 ky BP. As such, it is conceivable that the eruption played a role, whether direct or indirect, in shaping global-scale climate in the years, decades, and/or centuries that followed. Understanding the climatic response to Toba is important not only because the eruption represents an extreme atmospheric perturbation that is relevant to modeling future climate change, but also because the climate response may have slowed human population growth. Recent attempts to characterize either the regional or global climate response to Toba have been limited by a lack of age control, geographic proximity, and/or a convincing marker of the major eruption. Multiple U-Th-dated calcite stalagmites from Gunung Mulu National Park (Borneo; 4°N, 115°E) reveal a 1,000-year long period with elevated oxygen isotope values (δ18O; Carolin et al. 2013) that began abruptly and within error of the 40Ar/39Ar-dated Toba eruption (Storey et al., 2012). The δ18O shift is interpreted as a change in regional rainfall δ18O, and perhaps reflects a prolonged shift in the mean state of tropical climate. Microdrill analysis of the Mulu stalagmites showed that the abrupt onset of this period is marked by a large (>1‰) monotonic increase in δ18O. Here, we examine the structure of the abrupt δ18O increase at high-resolution in Mulu stalagmite "SC03". The WiscSIMS CAMECA IMS 1280 was used to measure δ18O in 857 spots along a 5.5 mm ( 1300 yr) linear, growth-axis traverse that is centered on the microdrilled δ18O shift. SIMS spot diameters are 6 mm in the growth dimension, 2 yr temporal resolution, with spot-to-spot δ18O reproducibility of ±0.3‰ (2 s.d.). The SIMS data reveal four δ18O excursions of ±2-3‰ over 6-10 spot intervals ( 10-20 yrs) during the 300 yr transition from GI-20 to GS-20, likely caused by fluctuations in

  11. The chemically zoned 1949 eruption on La Palma (Canary Islands): Petrologic evolution and magma supply dynamics of a rift zone eruption

    NASA Astrophysics Data System (ADS)

    Klügel, Andreas; Hoernle, Kaj A.; Schmincke, Hans-Ulrich; White, James D. L.

    2000-03-01

    The 1949 rift zone eruption along the Cumbre Vieja ridge on La Palma involved three eruptive centers, 3 km spaced apart, and was chemically and mineralogically zoned. Duraznero crater erupted tephrite for 14 days and shut down upon the opening of Llano del Banco, a fissure that issued first tephrite and, after 3 days, basanite. Hoyo Negro crater opened 4 days later and erupted basanite, tephrite, and phonotephrite, while Llano del Banco continued to issue basanite. The eruption ended with Duraznero erupting basanite with abundant crustal and mantle xenoliths. The tephrites and basanites from Duraznero and Llano del Banco show narrow compositional ranges and define a bimodal suite. Each batch ascended and evolved separately without significant intermixing, as did the Hoyo Negro basanite, which formed at lower degrees of melting. The magmas fractionated clinopyroxene +olivine±kaersutite±Ti-magnetite at 600-800 MPa and possibly 800-1100 MPa. Abundant reversely zoned phenocrysts reflect mixing with evolved melts at mantle depths. Probably as early as 1936, Hoyo Negro basanite entered the deep rift system at 200-350 MPa. Some shallower pockets of this basanite evolved to phonotephrite through differentiation and assimilation of wall rock. A few months prior to eruption, a mixing event in the mantle may have triggered the final ascent of the magmas. Most of the erupted tephrite and basanite ascended from mantle depths within hours to days without prolonged storage in crustal reservoirs. The Cumbre Vieja rift zone differs from the rift zones of Kilauea volcano (Hawaii) in lacking a summit caldera or a summit reservoir feeding the rift system and in being smaller and less active with most of the rift magma solidifying between eruptions.

  12. Eruptions of Lassen Peak, California, 1914 to 1917

    USGS Publications Warehouse

    Clynne, Michael A.; Christiansen, Robert L.; Felger, Tracey J.; Stauffer, Peter H.; Hendley, James W.

    1999-01-01

    On May 22, 1915, an explosive eruption at Lassen Peak, California, the southernmost active volcano in the Cascade Range, devastated nearby areas and rained volcanic ash as far away as 200 miles to the east. This explosion was the most powerful in a 1914–17 series of eruptions that were the last to occur in the Cascades before the 1980 eruption of Mount St. Helens, Washington. Recent work by scientists with the U.S. Geological Survey (USGS) in cooperation with the National Park Service is shedding new light on these eruptions.

  13. Solar filament material oscillations and drainage before eruption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bi, Yi; Jiang, Yunchun; Yang, Jiayan

    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 tomore » 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.« less

  14. 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.

  15. 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

  16. Hydrogen isotope investigation of amphibole and biotite phenocrysts in silicic magmas erupted at Lassen Volcanic Center, California

    USGS Publications Warehouse

    Underwood, S.J.; Feeley, T.C.; Clynne, M.A.

    2012-01-01

    prior to eruption, degassed vesiculated magma or lava had drained back down the volcanic conduit and mixed with less devolatilized magma. The vesiculated magma contained hydrous phenocrysts with lattice damage, which locally raised the effective H diffusion coefficient by ca 10–100 × and resulted in increased mineral dehydrogenation. Remobilization of dacite magma mush by relatively more reduced mafic magma appears to have generated further fO2 variations in May 1915 as oxidized magma from shallow levels circulated to depths where dehydrogenation of hydrous phenocrysts began. The δDMagmatic H2O expressed in LVC acid hot springs is likely a mixture derived from devolatilized ascending mafic magmas and crystallizing silicic magma mush.

  17. Detecting and Characterizing Repeating Earthquake Sequences During Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Tepp, G.; Haney, M. M.; Wech, A.

    2017-12-01

    A major challenge in volcano seismology is forecasting eruptions. Repeating earthquake sequences often precede volcanic eruptions or lava dome activity, providing an opportunity for short-term eruption forecasting. Automatic detection of these sequences can lead to timely eruption notification and aid in continuous monitoring of volcanic systems. However, repeating earthquake sequences may also occur after eruptions or along with magma intrusions that do not immediately lead to an eruption. This additional challenge requires a better understanding of the processes involved in producing these sequences to distinguish those that are precursory. Calculation of the inverse moment rate and concepts from the material failure forecast method can lead to such insights. The temporal evolution of the inverse moment rate is observed to differ for precursory and non-precursory sequences, and multiple earthquake sequences may occur concurrently. These observations suggest that sequences may occur in different locations or through different processes. We developed an automated repeating earthquake sequence detector and near real-time alarm to send alerts when an in-progress sequence is identified. Near real-time inverse moment rate measurements can further improve our ability to forecast eruptions by allowing for characterization of sequences. We apply the detector to eruptions of two Alaskan volcanoes: Bogoslof in 2016-2017 and Redoubt Volcano in 2009. The Bogoslof eruption produced almost 40 repeating earthquake sequences between its start in mid-December 2016 and early June 2017, 21 of which preceded an explosive eruption, and 2 sequences in the months before eruptive activity. Three of the sequences occurred after the implementation of the alarm in late March 2017 and successfully triggered alerts. The nearest seismometers to Bogoslof are over 45 km away, requiring a detector that can work with few stations and a relatively low signal-to-noise ratio. During the Redoubt

  18. Differentiation and magma mixing on Kilauea's east rift zone: A further look at the eruptions of 1955 and 1960. Part II. The 1960 lavas

    USGS Publications Warehouse

    Wright, T.L.; Helz, R.T.

    1996-01-01

    New and detailed petrographic observations, mineral compositional data, and whole-rock vs glass compositional trends document magma mixing in lavas erupted from Kilauea's lower east rift zone in 1960. Evidence includes the occurrence of heterogeneous phenocryst assemblages, including resorbed and reversely zoned minerals in the lavas inferred to be hybrids. Calculations suggest that this mixing, which is shown to have taken place within magma reservoirs recharged at the end of the 1955 eruption, involved introduction of four different magmas. These magmas originated beneath Kilauea's summit and moved into the rift reservoirs beginning 10 days after the eruption began. We used microprobe analyses of glass to calculate temperatures of liquids erupted in 1955 and 1960. We then used the calculated proportions of stored and recharge components to estimate the temperature of the recharge components, and found those temperatures to be consistent with the temperature of the same magmas as they appeared at Kilauea's summit. Our studies reinforce conclusions reached in previous studies of Kilauea's magmatic plumbing. We infer that magma enters shallow storage beneath Kilauea's summit and also moves laterally into the fluid core of the East rift zone. During this process, if magmas of distinctive chemistry are present, they retain their chemical identity and the amount of cooling is comparable for magma transported either upward or laterally to eruption sites. Intrusions within a few kilometers of the surface cool and crystallize to produce fractionated magma. Magma mixing occurs both within bodies of previously fractionated magma and when new magma intersects a preexisting reservoir. Magma is otherwise prevented from mixing, either by wall-rock septa or by differing thermal and density characteristics of the successive magma batches.

  19. 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.

  20. Precursory diffuse CO2 and H2S emission signatures of the 2011-2012 El Hierro submarine eruption, Canary Islands

    NASA Astrophysics Data System (ADS)

    Pérez, Nemesio M.; Padilla, Germán D.; Padrón, Eleazar; Hernández, Pedro A.; Melián, Gladys V.; Barrancos, José; Dionis, Samara; Nolasco, Dácil; Rodríguez, Fátima; Calvo, David; Hernández, Íñigo

    2012-08-01

    On October 12, 2011, a submarine eruption began 2 km off the coast of La Restinga, south of El Hierro Island. CO2 and H2S soil efflux were continuously measured during the period of volcanic unrest by using the accumulation chamber method at two different geochemical stations, HIE01 and HIE07. Recorded CO2 and H2S effluxes showed precursory signals that preceded the submarine eruption. Beginning in late August, the CO2 efflux time series started increasing at a relatively constant rate over one month, reaching a maximum of 19 gm-2d-1 one week before the onset of the submarine volcanic eruption. The H2S efflux time series at HIE07 showed a pulse in H2S emission just one day before the initiation of the submarine eruption, reaching peak values of 42 mg m-2 d-1, 10 times the average H2S efflux recorded during the observation period. Since CO2 and H2S effluxes are strongly influenced by external factors, we applied a multiple regression analysis to remove their contribution. A statistical analysis showed that the long-term trend of the filtered data is well correlated with the seismic energy. We find that these geochemical stations are important monitoring sites for evaluating the volcanic activity of El Hierro and that they demonstrate the potential of applying continuous monitoring of soil CO2 and H2S efflux to improve and optimize the detection of early warning signals of future volcanic unrest episodes at El Hierro. Continuous diffuse degassing studies would likely prove useful for monitoring other volcanoes during unrest episodes.

  1. Eruptive keratoacanthomas following carbon dioxide laser resurfacing.

    PubMed

    Gewirtzman, A; Meirson, D H; Rabinovitz, H

    1999-08-01

    Skin resurfacing with the carbon dioxide (CO2) laser is currently a popular means of improving rhytides and scars. Scarring, hyperpigmentation, hypopigmentation, and infection are among the complications that have been known to occur in some patients treated with the CO2 laser. We wish to communicate a previously unreported complication of CO2 laser resurfacing-multiple eruptive keratoacanthomas. We describe a 61-year-old woman who presented with multiple eruptive keratoacanthomas subsequent to CO2 laser resurfacing. Her lesions were cultured for fungus and bacteria. Biopsy specimens of two lesions were taken. Cultures were negative for pathogens. Biopsy specimens revealed atypical squamous epithelial proliferation and changes consistent with eruptive keratoacanthomas. Multiple eruptive keratoacanthomas should be considered as a rare complication of CO2 laser resurfacing.

  2. Triggering of Solar Magnetic Eruptions on Various Size Scales Alphonse Sterling

    NASA Technical Reports Server (NTRS)

    Sterling, A.C.

    2010-01-01

    A solar eruption that produces a coronal mass ejection (CME) together with a flare is driven by the eruption of a closed-loop magnetic arcade that has a sheared-field core. Before eruption, the sheared core envelops a polarity inversion line along which cool filament material may reside. The sheared-core arcade erupts when there is a breakdown in the balance between the confining downward-directed magnetic tension of the overall arcade field and the upward-directed force of the pent-up magnetic pressure of the sheared field in the core of the arcade. What triggers the breakdown in this balance in favor of the upward-directed force is still an unsettled question. We consider several eruption examples, using imaging data from the SoHO, TRACE and Hinode satellites, and other sources, along with information about the magnetic field of the erupting regions. In several cases, observations of large-scale eruptions, where the magnetic neutral line spans few x 10,000 km, are consistent with magnetic flux cancellation being the trigger to the eruption's onset, even though the amount of flux canceled is only few percent of the total magnetic flux of the erupting region. In several other cases, an initial compact (small size-scale) eruption occurs embedded inside of a larger closed magnetic loop system, so that the smaller eruption destabilizes and causes the eruption of the much larger system. In this way, small-scale eruptive events can result in eruption of much larger-scale systems.

  3. Conduit stability effects on intensity and steadiness of explosive eruptions.

    PubMed

    Aravena, Álvaro; Cioni, Raffaello; de'Michieli Vitturi, Mattia; Neri, Augusto

    2018-03-07

    Conduit geometry affects magma ascent dynamics and, consequently, the style and evolution of volcanic eruptions. However, despite geological evidences support the occurrence of conduit widening during most volcanic eruptions, the factors controlling conduit enlargement are still unclear, and the effects of syn-eruptive variations of conduit geometry have not been investigated in depth yet. Based on numerical modeling and the application of appropriate stability criteria, we found out a strong relationship between magma rheology and conduit stability, with significant effects on eruptive dynamics. Indeed, in order to be stable, conduits feeding dacitic/rhyolitic eruptions need larger diameters respect to their phonolitic/trachytic counterparts, resulting in the higher eruption rates commonly observed in dacitic/rhyolitic explosive events. Thus, in addition to magma source conditions and viscosity-dependent efficiency for outgassing, we suggest that typical eruption rates for different magma types are also controlled by conduit stability. Results are consistent with a compilation of volcanological data and selected case studies. As stability conditions are not uniform along the conduit, widening is expected to vary in depth, and three axisymmetric geometries with depth-dependent radii were investigated. They are able to produce major modifications in eruptive parameters, suggesting that eruptive dynamics is influenced by syn-eruptive changes in conduit geometry.

  4. 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

  5. Contrasting modes of rifting: The Benue Trough and Cameroon Volcanic Line, West Africa

    NASA Astrophysics Data System (ADS)

    Okereke, C. S.

    1988-08-01

    The Benue trough of west Africa is commonly believed to be a rift feature that originated in the Cretaceous at about the time that Africa and South America began to separate. Bouguer gravity and available geological data in the trough indicate that its formation was probably the result of regional horizontal stresses in the lithosphere, causing crustal extension and surface subsidence. By contrast, the data for the adjoining Cameroon volcanic line suggests that the associated tensional stresses relate to mantle upwarp causing thinning of the lithosphere and regional crustal uplift similar to that associated with the Kenya rift. Thus the association of passive and active rifts seen in the Afro-Arabia rift system is also a feature of the Cretaceous rift system in west Africa.

  6. Filament Eruptions, Jets, and Space Weather

    NASA Technical Reports Server (NTRS)

    Moore, Ronald; Sterling, Alphonse; Robe, Nick; Falconer, David; Cirtain, Jonathan

    2013-01-01

    Previously, from chromospheric H alpha and coronal X-ray movies of the Sun's polar coronal holes, it was found that nearly all coronal jets (greater than 90%) are one or the other of two roughly equally common different kinds, different in how they erupt: standard jets and blowout jets (Yamauchi et al 2004, Apl, 605, 5ll: Moore et all 2010, Apj, 720, 757). Here, from inspection of SDO/AIA He II 304 A movies of 54 polar x-ray jets observed in Hinode/XRT movies, we report, as Moore et al (2010) anticipated, that (1) most standard x-ray jets (greater than 80%) show no ejected plasma that is cool enough (T is less than or approximately 10(exp 5K) to be seen in the He II 304 A movies; (2) nearly all blownout X-ray jets (greater than 90%) show obvious ejection of such cool plasma; (3) whereas when cool plasma is ejected in standard X-ray jets, it shows no lateral expansion, the cool plasma ejected in blowout X-ray jets shows strong lateral expansion; and (4) in many blowout X-ray jets, the cool plasma ejection displays the erupting-magnetic-rope form of clasic filament eruptions and is thereby seen to be a miniature filament eruption. The XRT movies also showed most blowout X-ray jets to be larger and brighter, and hence to apparently have more energy, than most standard X-ray jets. These observations (1) confirm the dichotomy of coronal jets, (2) agree with the Shibata model for standard jets, and (3) support the conclusion of Moore et al (2010) that in blowout jets the magnetic-arch base of the jet erupts in the manner of the much larger magnetic arcades in which the core field, the field rooted along the arcade's polarity inversion line, is sheared and twisted (sigmoid), often carries a cool-plasma filament, and erupts to blowout the arcade, producing a CME. From Hinode/SOT Ca II movies of the polar limb, Sterling et al (2010, ApJ, 714, L1) found that chromospheric Type-II spicules show a dichotomy of eruption dynamics similar to that found here for the cool

  7. Tephra productivity and eruption flux of the subglacial Katla volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Óladóttir, Bergrún Arna; Sigmarsson, Olgeir; Larsen, Guðrún

    2018-07-01

    The influence of the mode of magma ascent on eruption fluxes is uncertain beneath active volcanoes. To study this, the subglacial volcano Katla, Iceland, whichhas produced abundant tephra through the Holocene, has been investigated through volume estimations of the largest eruptions from the last 3500 years. Tephra volume measurements allow tephra productivity and their variation through time to be estimated. By adding the volume of lava from effusive eruptions, the total eruption flux is obtained. Tephra productivity shows variations with time, ranging from 2.0 km3/century, during the prehistoric period examined, to 0.7 km3/century, during historical time (after 939 CE). However, the average eruption flux remained unchanged ( 2.2 km3/century) during the studied 3500 years due to the large lava produced during the Eldgjá flood basalt eruption (939 CE). Following the Eldgjá event, tephra production declined and also eruption frequency, decreasing from 5.6-2.0 eruptions/century. Magma ascending vertically to the glacier -covered volcano results in explosive phreatomagmatic eruptions and tephra formation, whereas magma transferred in a laterally extended dyke leads to predominant fissural eruptions outside the glacier (e.g., Eldgjá). The mode of magma ascent thus exerts control on the eruption frequency and the volcanic style at Katla volcano without affecting the long-term eruption flux. A uniform increase in cumulative magma volume from Katla suggests a time-integrated steady-state behavior over the last 3500 years. Finally, although the large fissural eruption of Eldgjá lowered the following eruption frequency, it only temporarily affected the time averaged eruption flux of Katla.

  8. Effects of scoria-cone eruptions upon nearby human communities

    USGS Publications Warehouse

    Ort, M.H.; Elson, M.D.; Anderson, K.C.; Duffield, W.A.; Hooten, J.A.; Champion, D.E.; Waring, G.

    2008-01-01

    Scoria-cone eruptions are typically low in volume and explosivity compared with eruptions from stratovolcanoes, but they can affect local populations profoundly. Scoria-cone eruption effects vary dramatically due to eruption style, tephra blanket extent, climate, types of land use, the culture and complexity of the affected group, and resulting governmental action. A comparison of a historic eruption (Pari??cutin, Me??xico) with prehistoric eruptions (herein we primarily focus on Sunset Crater in northern Arizona, USA) elucidates the controls on and effects of these variables. Long-term effects of lava flows extend little beyond the flow edges. These flows, however, can be used for defensive purposes, providing refuges from invasion for those who know them well. In arid lands, tephra blankets serve as mulches, decreasing runoff and evaporation, increasing infiltration, and regulating soil temperature. Management and retention of these scoria mulches, which can open new areas for agriculture, become a priority for farming communities. In humid areas, though, the tephra blanket may impede plant growth and increase erosion. Cultural responses to eruptions vary, from cultural collapse, through fragmentation of society, dramatic changes, and development of new technologies, to little apparent change. Eruptions may also be viewed as retribution for poor behavior, and attempts are made to mollify angry gods. ?? 2008 Geological Society of America.

  9. Mount St. Helens eruptive behavior during the past 1500 yr.

    USGS Publications Warehouse

    Hoblitt, R.P.; Crandell, D.R.; Mullineaux, D.R.

    1980-01-01

    During the past 1500 yr Mount St. Helens, Washington, has repeatedly erupted dacite domes, tephra, and pyroclastic flows as well as andesite lava flows and tephra. Two periods of activity prior to 1980, each many decades long, were both initiated by eruptions of volatile-rich dacite which were followed by andesite, then by dacite. A third eruptive period was characterized by the eruption of volatile-poor dacite that formed a dome and minor pyroclastic flows. The prolonged duration of some previous eruptive periods suggests that the current activity could continue for many years. The volatile-rich dacite that has been erupted to date probably will be followed by gas-poor magma, but it cannot yet be predicted whether a more mafic magma will be extruded during the current eruptive period.-Authors

  10. Magmatic Ascent and Eruption Processes on Mercury

    NASA Astrophysics Data System (ADS)

    Head, J. W.; Wilson, L.

    2018-05-01

    MESSENGER volcanic landform data and information on crustal composition allow us to model the generation, ascent, and eruption of magma; Mercury explosive and effusive eruption processes differ significantly from other terrestrial planetary bodies.

  11. The Origin, Early Evolution and Predictability of Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Green, Lucie M.; Török, Tibor; Vršnak, Bojan; Manchester, Ward; Veronig, Astrid

    2018-02-01

    Coronal mass ejections (CMEs) were discovered in the early 1970s when space-borne coronagraphs revealed that eruptions of plasma are ejected from the Sun. Today, it is known that the Sun produces eruptive flares, filament eruptions, coronal mass ejections and failed eruptions; all thought to be due to a release of energy stored in the coronal magnetic field during its drastic reconfiguration. This review discusses the observations and physical mechanisms behind this eruptive activity, with a view to making an assessment of the current capability of forecasting these events for space weather risk and impact mitigation. Whilst a wealth of observations exist, and detailed models have been developed, there still exists a need to draw these approaches together. In particular more realistic models are encouraged in order to asses the full range of complexity of the solar atmosphere and the criteria for which an eruption is formed. From the observational side, a more detailed understanding of the role of photospheric flows and reconnection is needed in order to identify the evolutionary path that ultimately means a magnetic structure will erupt.

  12. Effects of volcanic eruptions on China's monsoon precipitation over the past 700 years

    NASA Astrophysics Data System (ADS)

    Zhuo, Z.; Gao, C.

    2013-12-01

    Tropical volcanic eruptions were found to affect precipitation especially in Asia and Africa monsoon region. However, studies with different types of eruptions suggested different impacts as well as the spatial patterns. In this study, we combined the Monsoon Asia Drought Atlas (MADA, [Cook et al., 2010]) and the Chinese Historical Drought Disaster Index (CHDDI) compiled from the historic meteorological records to study the effect of volcanic eruptions on China's monsoon precipitation over the past 700 years. Histories of past volcanism were compiled from the IVI2[Gao et al., 2008] and Crowley2013[Crowley and Unterman, 2013] reconstructions. Volcanic events were classified into 2×Pinatubo, 1×Pinatubo , ≥5 Tg sulfate aerosols injection in the northern hemisphere (NH) stratosphere for IVI2; and NH sulfate flux more than 20/15/10/5 kg km-2 for Crowley2013. In both cases, average MADA show a drying trend over mainland China from year zero(0) to year three(+3) after the eruption; and the more sulfate aerosol injected into the NH stratosphere or the larger the sulfate flux, the more severe this drying trend seem to reveal. In comparison, a wetting trend was found in the eruption year with Southern Hemisphere (SH) only injections. Superposed epoch analysis with a 10,000 Monte Carlo resampling procedure showed that 97.9% (96.9%) of the observed MADA values are statistically significant at the 95% (99%) confidence level. The drying is probably caused by a reduction of the latent heat flux due to volcanic aerosol' cooling effect, leading to the weakening of south Asian monsoon and decrease of moisture vapor over tropical oceans, which contribute to a reduced moisture flux over china. Spatial distribution of the average MADA show a southward movement of the driest areas in eastern China from year zero to year three after the 1×Pinatubo and 2×Pinatubo eruptions, whereas part of north china experienced unusual wetting condition. This is in good agreement with CHDDI, which

  13. Arching Eruption

    NASA Image and Video Library

    2015-06-30

    NASA’s Solar Dynamics Observatory caught this image of an eruption on the side of the sun on June 18, 2015. The eruption ultimately escaped the sun, growing into a substantial coronal mass ejection, or CME — a giant cloud of solar material traveling through space. This imagery is shown in the 304 Angstrom wavelength of extreme ultraviolet light, a wavelength that highlights material in the low parts of the sun’s atmosphere and that is typically colorized in red. The video clip covers about four hours of the event. Credit: NASA/Goddard/SDO Download: svs.gsfc.nasa.gov/goto?11908 NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  14. Modeling Explosive Eruptions at Kīlauea, Hawai'i

    NASA Astrophysics Data System (ADS)

    Gonnermann, H. M.; Ferguson, D. J.; Blaser, A. P.; Houghton, B. F.; Plank, T. A.; Hauri, E. H.; Swanson, D. A.

    2014-12-01

    We have modeled eruptive magma ascent during two explosive eruptions of Kīlauea volcano, Hawai'i. They are the Hawaiian style Kīlauea Iki eruption, 1959, and the subplinian Keanakāko'i eruption, 1650 CE. We have modeled combined magma ascent in the volcanic conduit and exsolution of H2O and CO2 from the erupting magma. To better assess the relative roles of conduit processes and magma chamber, we also coupled conduit flow and magma chamber through mass balance and pressure. We predict magma discharge rates, superficial gas velocities, H2O and CO2 concentrations of the melt, magma chamber pressure, surface deformation, and height of the volcanic jet. Models are in part constrained by H2O and CO2 measured in olivine-hosted melt inclusions and by decompression rates recorded in melt embayment diffusion profiles. We present a parametric analysis, indicating that the pressure within the chamber that fed the subplinian Keanakāko'i eruption was significantly higher than lithostatic pressure. In contrast, chamber pressure for the Hawaiian Kīlauea Iki eruption was close to lithostatic. In both cases the superficial gas velocity, which affects the geometrical distribution of gas-liquid mixtures during upward flow in conduits, may have exceeded values at which bubble coalescence did not affect the flow.

  15. The latest explosive eruptions of Ciomadul (Csomád) volcano, East Carpathians - A tephrostratigraphic approach for the 51-29 ka BP time interval

    NASA Astrophysics Data System (ADS)

    Karátson, D.; Wulf, S.; Veres, D.; Magyari, E. K.; Gertisser, R.; Timar-Gabor, A.; Novothny, Á.; Telbisz, T.; Szalai, Z.; Anechitei-Deacu, V.; Appelt, O.; Bormann, M.; Jánosi, Cs.; Hubay, K.; Schäbitz, F.

    2016-06-01

    The most recent, mainly explosive eruptions of Ciomadul, the youngest volcano in the Carpatho-Pannonian Region, have been constrained by detailed field volcanological studies, major element pumice glass geochemistry, luminescence and radiocarbon dating, and a critical evaluation of available geochronological data. These investigations were complemented by the first tephrostratigraphic studies of the lacustrine infill of Ciomadul's twin craters (St. Ana and Mohoş) that received tephra deposition during the last eruptions of the volcano. Our analysis shows that significant explosive activity, collectively called EPPA (Early Phreatomagmatic and Plinian Activity), started at Ciomadul in or around the present-day Mohoş, the older crater, at ≥ 51 ka BP. These eruptions resulted in a thick succession of pyroclastic-fall deposits found in both proximal and medial/distal localities around the volcano, characterized by highly silicic (rhyolitic) glass chemical compositions (ca. 75.2-79.8 wt.% SiO2). The EPPA stage was terminated by a subplinian/plinian eruption at ≥ 43 ka BP, producing pumiceous pyroclastic-fall and -flow deposits of similar glass composition, probably from a "Proto-St. Ana" vent located at or around the younger crater hosting the present-day Lake St. Ana. After a quiescent period with a proposed lava dome growth in the St. Ana crater, a new explosive stage began, defined as MPA (Middle Plinian Activity). In particular, a significant two-phase eruption occurred at 31.5 ka BP, producing pyroclastic flows from vulcanian explosions disrupting the preexisting lava dome of Sf. Ana, and followed by pumiceous fallout from a plinian eruption column. Related pyroclastic deposits show a characteristic, less evolved rhyolitic glass composition (ca. 70.2-74.5 wt.% SiO2) and occur both in proximal and medial/distal localities up to 21 km from source. The MPA eruptions, that may have pre-shaped a crater similar to, but possibly smaller than, the present-day St. Ana

  16. Juvenile Spring Eruption: A Variant of Perniosis?

    PubMed

    Nabatian, Adam S; Rosman, Ilana S; Sturza, Jeffrey; Jacobson, Mark

    2015-09-01

    Juvenile spring eruption (JSE) is a unique condition that typically affects the helices of the ears of boys and young men. The classical clinical picture of JSE includes the abrupt onset of lesions after spending time outdoors in the early spring. Because of the papulovesicular nature of the rash and the history of sun exposure, JSE is considered a variant of polymorphous light eruption. In addition to the term "juvenile spring eruption," this entity has also been described under other less common terms such as "perniosis juvenilis vernalis aurium" or "spring perniosis," which emphasizes the onset in the spring and the possible pathogenic role of cold weather. We present a case of likely JSE with histopathologic features more consistent with perniosis than polymorphous light eruption and present a review the literature.

  17. Towards forecasting volcanic eruptions on a global scale

    NASA Astrophysics Data System (ADS)

    Hooper, A. J.; Heimisson, E. R.; Gaddes, M.; Bagnardi, M.; Sigmundsson, F.; Spaans, K.; Parks, M.; Gudmundsson, M. T.; Ebmeier, S. K.; Holohan, E. P.; Wright, T. J.; Jonsdottir, K.; Hreinsdottir, S.; Dumont, S.; Ofeigsson, B.; Vogfjord, K. S.

    2016-12-01

    Volcanic eruptions can cause loss of life, damage health, and have huge economic impacts, providing strong societal motivation for predicting eruptive behavior prior to and during eruptions. I will present here recent progress we have made in mechanical modelling with a predictive capacity, and how we are expanding volcano monitoring to a global scale. The eruption of Bardarbunga volcano, Iceland, in 2014-2015 was the largest eruption there for more than 200 years, producing 1.6 km3of lava. Prior to eruption, magma propagated almost 50 km beneath the surface, over a period of two weeks. Key questions to answer in advance of such eruptions are: will it erupt, where, how much and for how long? We developed a model based on magma taking a path that maximizes energy release, which aligns well with the actual direction taken. Our model also predicts eruption in a topographic low, as actually occurred. As magma was withdrawn, the volcano surface sagged downwards. A coupled model of magma flow and piston-like collapse predicts a declining magma flow rate and ground subsidence rate, in accordance with that observed. With such a model, observations can be used to predict the timescale and rates of eruption, even before one starts. The primary data needed to constrain these predictive models are measurements of surface deformation. In Iceland, this is achieved using high accuracy GPS, however, most volcanoes have no ground instrumentation. A recent ESA mission, Sentinel-1, can potentially image deformation at almost all subaerial volcanoes every 6 days, using a technique called interferometric synthetic aperture radar (InSAR). This will allow us to detect early stages of magma migration at any volcano, then task other satellites to acquire data at a higher rate. We are working on a system to process all Sentinel-1 data in near-real time, which is a big data challenge. We have also developed new algorithms that maximize signal extraction from each new acquisition and

  18. 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

  19. How does tooth eruption relate to vertical mandibular growth displacement?

    PubMed

    Liu, Sean Shih-Yao; Buschang, Peter H

    2011-06-01

    Our objectives were to investigate the eruptive patterns of the mandibular teeth and assess their associations with mandibular growth displacements. Cephalograms for a mixed-longitudinal sample of 124 French-Canadian girls were evaluated between 10 and 15 years of age. Vertical mandibular displacement and mandibular eruption were evaluated by using cranial and mandibular superimpositions, respectively. Multilevel modeling procedures were used to estimate each subject's growth change over time. Stepwise multiple regressions were used to determine the amount and relative magnitudes of variations in mandibular eruption explained by mandibular growth displacement, controlling for vertical maxillary tooth movements. Cubic polynomial models explained between 91% and 98% of the variations in eruption and vertical growth displacement. All curves showed acceleration of eruption until approximately 12 years of age, after which eruption decelerated. The eruption of the mandibular teeth demonstrated greater relative variability than did vertical mandibular growth displacements. Independent of the overall movements of the maxillary molars, inferior mandibular growth displacement explained approximately 54% of the variation in mandibular molar eruption between 10.5 and 14.5 years of age. Inferior mandibular growth displacement and dental eruption followed similar patterns of change during adolescence. Based on their associations and the differences in variability identified, mandibular eruption appears to compensate for or adapt to growth displacements. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  20. The 1994-2001 eruptive period at Rabaul, Papua New Guinea: Petrological and geochemical evidence for basalt injections into a shallow dacite magma reservoir, and significant SO2 flux

    NASA Astrophysics Data System (ADS)

    Patia, H.; Eggins, S. M.; Arculus, R. J.; McKee, C. O.; Johnson, R. W.; Bradney, A.

    2017-10-01

    The eruptions that began at Rabaul Caldera on 19 September 1994 had two focal points, the vents Tavurvur and Vulcan, located 6 km apart on opposing sides of the caldera. Vulcan eruptives define a tight cluster of dacite compositions, whereas Tavurvur eruptives span an array from equivalent dacite compositions to mafic andesites. The eruption of geochemically and mineralogically identical dacites from both vents indicates sourcing from the same magma reservoir. This, together with previously reported H2O-CO2 volatile contents of dacite melt inclusions, a caldera-wide seismic low-velocity zone, and a seismically active caldera ring fault structure are consistent with the presence at 3-6 km depth of an extensive, tabular dacitic magma body having volume of about 15-150 km3. The Tavurvur andesites form a linear compositional array and have strongly bimodal phenocryst assemblages that reflect dacite hybridisation with a mafic basalt. The moderately large volume SO2 flux documented in the Tavurvur volcanic plume (and negligible SO2 flux in the Vulcan plume) combined with high dissolved S contents of basaltic melt inclusions trapped in olivine of Tavurvur eruptives, indicate that the amount of degassed basaltic magma was 0.1 km3 and suggest that the injection of this magma was confined to the Tavurvur-side (eastern to northeastern sector) of the caldera. Circumstantial evidence suggests that the eruption was triggered and evolved in response to a series of basaltic magma injections that may have commenced in 1971 and continued up until at least the start of the 1994 eruptions. The presence of zoned plagioclase phenocrysts reflecting older basalt-dacite interaction events (i.e. anorthite cores overgrown with thick andesine rims), evaluation of limited available data for the products of previous eruptions in 1878 and 1937-1943, and the episodic occurrence of major intra-caldera seismo-deformational events indicates that the shallow magma system at Rabaul Caldera is

  1. Geyser preplay and eruption in a laboratory model with a bubble trap

    NASA Astrophysics Data System (ADS)

    Adelstein, Esther; Tran, Aaron; Saez, Carolina Muñoz; Shteinberg, Alexander; Manga, Michael

    2014-09-01

    We present visual observations and temperature measurements from a laboratory model of a geyser. Our model incorporates a bubble trap, a zone in which vapor can accumulate in the geyser's subsurface plumbing, in a vertical conduit connected to a basal chamber. Analogous features have been identified at several natural geysers. We observe three types of eruptions: 1) rising bubbles eject a small volume of liquid in a weak spout (small eruption); 2) boiling occurs in the conduit above the bubble trap (medium eruption); and 3) boiling occurs in the conduit and chamber (large eruption). In the last two cases, boiling in the conduit causes a rapid hydrostatic pressure drop that allows for the rise and eruption of liquid water in a vigorous spout. Boiling initiates at depth rather than propagating downward from the surface. In a single eruption cycle, multiple small eruptions precede every medium and large eruption. At least one eruption cycle that culminates in a medium eruption (i.e., a quiescent period followed by a series of small eruptions leading up to a medium eruption) precedes every eruption cycle that culminates in a large eruption. We find that the transfer of fluid with high enthalpy to the upper conduit during small and medium eruptions is necessary to heat the upper conduit and prepare the system for the full boiling required for a large eruption. The placement of the bubble trap midway up the conduit allows for more efficient heating of the upper conduit. Our model provides insight into the influence of conduit geometry on eruption style and the importance of heat transfer by smaller events in preparing the geyser system for eruption.

  2. 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

  3. A Management Framework for Training Providers to Improve Workplace Skills Development in South Africa

    ERIC Educational Resources Information Center

    Bisschoff, Tom; Govender, Cookie

    2007-01-01

    Deputy President, Ms Phumzile Mlambo-Ngcuka, says a skills revolution is necessary for South Africa's (SA) skills crisis. The SA skills revolution began with the skills legislation of 1998-1999 when the Departments of Labour and Education intended a seamless, integrated approach to rapid skills development. The National Skills Development…

  4. Observing eruptions of gas-rich compressible magmas from space

    PubMed Central

    Kilbride, Brendan McCormick; Edmonds, Marie; Biggs, Juliet

    2016-01-01

    Observations of volcanoes from space are a critical component of volcano monitoring, but we lack quantitative integrated models to interpret them. The atmospheric sulfur yields of eruptions are variable and not well correlated with eruption magnitude and for many eruptions the volume of erupted material is much greater than the subsurface volume change inferred from ground displacements. Up to now, these observations have been treated independently, but they are fundamentally linked. If magmas are vapour-saturated before eruption, bubbles cause the magma to become more compressible, resulting in muted ground displacements. The bubbles contain the sulfur-bearing vapour injected into the atmosphere during eruptions. Here we present a model that allows the inferred volume change of the reservoir and the sulfur mass loading to be predicted as a function of reservoir depth and the magma's oxidation state and volatile content, which is consistent with the array of natural data. PMID:28000791

  5. The Influence of Conduit Processes During Basaltic Plinian Eruptions.

    NASA Astrophysics Data System (ADS)

    Houghton, B. F.; Sable, J. E.; Wilson, C. J.; Coltelli, M.; Del Carlo, P.

    2001-12-01

    Basaltic volcanism is most typically thought to produce effusion of lava, with the most explosive manifestations ranging from mild Strombolian activity to more energetic fire fountain eruptions. However, some basaltic eruptions are now recognized as extremely violent, i.e. generating widespread phreatomagmatic, subplinian and Plinian fall deposits. These eruptions are particularly dangerous because the ascent rate of basaltic magma prior to eruption can be very rapid (giving warning times as little as a few hours) and because their precursors may be ignored or misunderstood. The main question addressed in this talk is: what conditions in the conduit cause basaltic magma to adopt an eruption style more typical of chemically evolved, highly viscous magmas? Possible mechanisms (acting singly, or in concert) are: (1) interaction between magma and water, (ii) very rapid ascent producing a delayed onset of degassing then exceptionally rapid "runaway" vesiculation at shallow levels in the conduit, (iii) microlite crystallization and degassing of the magma during ascent leading to increased viscosity. We focus here on two examples of basaltic Plinian volcanism: the 1886 eruption of Tarawera, New Zealand, which is the youngest known basaltic Plinian eruption and the only one for which there are detailed written eyewitness accounts, and the well documented 122 BC eruption of Mount Etna, Italy. Field and laboratory evidence suggests that the Plinian phase of the 1886 eruption was a consequence of two processes. Firstly rheologic changes during magma ascent accompanied early (pre-fragmentation) interaction between the basaltic melt and water-bearing rhyolitic units forming the conduit walls and, secondly, late-stage magma:water interaction. In contrast, during the 122 BC eruption tectonic processes, such as slope failure or permanent displacement of a mobile flank of the volcano, appear to have triggered exceptionally rapid ascent, delayed onset of degassing and exceptionally

  6. A solar eruption driven by rapid sunspot rotation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ruan, Guiping; Chen, Yao; Du, Guohui

    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,more » 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.« less

  7. Impact of Future Volcanic Eruptions on Stratospheric Ozone

    NASA Astrophysics Data System (ADS)

    Wilmouth, D. M.; Klobas, J. E.; Weisenstein, D.; Anderson, J. G.; Salawitch, R. J.

    2017-12-01

    Due to the anthropogenic release of chlorine-containing chemicals such as chlorofluorocarbons into the atmosphere in the twentieth century, a large volcanic eruption occurring today would initiate chemical reactions that reduce the thickness of the ozone layer. In the future, when atmospheric levels of chlorine are reduced, large volcanic eruptions are instead expected to increase the thickness of the ozone layer, but important details relevant to this shift in volcanic impact are not well known. Here we use the AER-2D chemical transport model to simulate a Pinatubo-like volcanic eruption in contemporary and future atmospheres. In particular, we explore the sensitivity of column ozone to volcanic eruption for four different climate change scenarios over the remainder of this century and also establish the importance of bromine-containing very short-lived substances (VSLS) in determining whether future eruptions will lead to ozone depletion. We find that the ozone layer will be vulnerable to volcanic perturbation for considerably longer than previously believed. Finally, we consider the impact on column ozone of inorganic halogens being co-injected into the stratosphere following future explosive eruptions using realistic hydrogen halide to sulfur dioxide ratios.

  8. Photogrammetric monitoring of lava dome growth during the 2009 eruption of Redoubt Volcano

    USGS Publications Warehouse

    Diefenbach, Angela K.; Bull, Katharine F.; Wessels, Rick; McGimsey, Robert G.

    2013-01-01

    The 2009 eruption of Redoubt Volcano, Alaska, began with a phreatic explosion on 15 March followed by a series of at least 19 explosive events and growth and destruction of at least two, and likely three, lava domes between 22 March and 4 April. On 4 April explosive activity gave way to continuous lava effusion within the summit crater. We present an analysis of post-4 April lava dome growth using an oblique photogrammetry approach that provides a safe, rapid, and accurate means of measuring dome growth. Photogrammetric analyses of oblique digital images acquired during helicopter observation flights and fixed-wing volcanic gas surveys produced a series of digital elevation models (DEMs) of the lava dome from 16 April to 23 September. The DEMs were used to calculate estimates of volume and time-averaged extrusion rates and to quantify morphological changes during dome growth.Effusion rates ranged from a maximum of 35 m3 s− 1 during the initial two weeks to a low of 2.2 m3 s− 1 in early summer 2009. The average effusion rate from April to July was 9.5 m3 s− 1. Early, rapid dome growth was characterized by extrusion of blocky lava that spread laterally within the summit crater. In mid-to-late April the volume of the dome had reached 36 × 106 m3, roughly half of the total volume, and dome growth within the summit crater began to be limited by confining crater walls to the south, east, and west. Once the dome reached the steep, north-sloping gorge that breaches the crater, growth decreased to the south, but the dome continued to inflate and extend northward down the gorge. Effusion slowed during 16 April–1 May, but in early May the rate increased again. This rate increase was accompanied by a transition to exogenous dome growth. From mid-May to July the effusion rate consistently declined. The decrease is consistent with observations of reduced seismicity, gas emission, and thermal anomalies, as well as declining rates of geodetic deflation or

  9. Aleutian volcanic eruption taken by Expedition 13 crewmember

    NASA Image and Video Library

    2006-05-23

    ISS013-E-24184 (23 May 2006) --- Eruption of Cleveland Volcano, Aleutian Islands, Alaska is featured in this image photographed by an Expedition 13 crewmember on the International Space Station. This most recent eruption was first reported to the Alaska Volcano Observatory by astronaut Jeffrey N. Williams, NASA space station science officer and flight engineer, at 3:00 p.m. Alaska Daylight Time (23:00 GMT). This image, acquired shortly after the beginning of the eruption, captures the ash plume moving west-southwest from the summit vent. The eruption was short-lived; the plume had completely detached from the volcano summit two hours later.

  10. The ash deposits of the 4200 BP Cerro Blanco eruption: the largest Holocene eruption of the Central Andes

    NASA Astrophysics Data System (ADS)

    Fernandez-Turiel, Jose-Luis; Saavedra, Julio; Perez-Torrado, Francisco-Jose; Rodriguez-Gonzalez, Alejandro; Carracedo, Juan-Carlos; Lobo, Agustin; Rejas, Marta; Gallardo, Juan-Fernando; Osterrieth, Margarita; Carrizo, Julieta; Esteban, Graciela; Martinez, Luis-Dante; Gil, Raul-Andres; Ratto, Norma; Baez, Walter

    2015-04-01

    We present new data about a major eruption -spreading approx. 110 km3 ashes over 440.000 km2- long thought to have occurred around 4200 years ago in the Cerro Blanco Volcanic Complex (CBVC) in the Central Andes of NW Argentina (Southern Puna, 26°45' S, 67°45' W). This eruption may be the biggest during the past five millennia in the Central Volcanic Zone of the Andes, and possibly one of the largest Holocene eruptions in the world. Discrimination and correlation of pyroclastic deposits of this eruption of Cerro Blanco was conducted comparing samples of proximal (domes, pyroclastic flow and fall deposits) with distal ash fall deposits (up to 400 km from de vent). They have been characterized using optical and electron microscopy (SEM), X-ray diffraction, particle-size distribution by laser diffraction and electron microprobe and HR-ICP-MS with laser ablation for major and trace element composition of glass, feldspars and biotite. New and published 14C ages were calibrated using Bayesian statistics. An one-at-a-time inversion method was used to reconstruct the eruption conditions using the Tephra2 code (Bonadonna et al. 2010, https://vhub.org/resources/tephra2). This method allowed setting the main features of the eruption that explains the field observations in terms of thickness and grain size distributions of the ash fall deposit. The main arguments that justify the correlation are four: 1) Compositional coincidence for glass, feldspars, and biotite in proximal and distal materials; 2) Stratigraphic and geomorphological relationships, including structure and thickness variation of the distal deposits; 3) Geochronological consistency, matching proximal and distal ages; and 4) Geographical distribution of correlated outcrops in relation to the eruption centre at the coordinates of Cerro Blanco. With a magnitude of 7.0 and a volcanic explosivity index or VEI 7, this eruption of ~4200 BP at Cerro Blanco is the largest in the last five millennia known in the Central

  11. Characterize Eruptive Processes at Yucca Mountain, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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. Withinmore » 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.« less

  12. Beyond eruptive scenarios: assessing tephra fallout hazard from Neapolitan volcanoes

    PubMed Central

    Sandri, Laura; Costa, Antonio; Selva, Jacopo; Tonini, Roberto; Macedonio, Giovanni; Folch, Arnau; Sulpizio, Roberto

    2016-01-01

    Assessment of volcanic hazards is necessary for risk mitigation. Typically, hazard assessment is based on one or a few, subjectively chosen representative eruptive scenarios, which use a specific combination of eruptive sizes and intensities to represent a particular size class of eruption. While such eruptive scenarios use a range of representative members to capture a range of eruptive sizes and intensities in order to reflect a wider size class, a scenario approach neglects to account for the intrinsic variability of volcanic eruptions, and implicitly assumes that inter-class size variability (i.e. size difference between different eruptive size classes) dominates over intra-class size variability (i.e. size difference within an eruptive size class), the latter of which is treated as negligible. So far, no quantitative study has been undertaken to verify such an assumption. Here, we adopt a novel Probabilistic Volcanic Hazard Analysis (PVHA) strategy, which accounts for intrinsic eruptive variabilities, to quantify the tephra fallout hazard in the Campania area. We compare the results of the new probabilistic approach with the classical scenario approach. The results allow for determining whether a simplified scenario approach can be considered valid, and for quantifying the bias which arises when full variability is not accounted for. PMID:27067389

  13. Beyond eruptive scenarios: assessing tephra fallout hazard from Neapolitan volcanoes.

    PubMed

    Sandri, Laura; Costa, Antonio; Selva, Jacopo; Tonini, Roberto; Macedonio, Giovanni; Folch, Arnau; Sulpizio, Roberto

    2016-04-12

    Assessment of volcanic hazards is necessary for risk mitigation. Typically, hazard assessment is based on one or a few, subjectively chosen representative eruptive scenarios, which use a specific combination of eruptive sizes and intensities to represent a particular size class of eruption. While such eruptive scenarios use a range of representative members to capture a range of eruptive sizes and intensities in order to reflect a wider size class, a scenario approach neglects to account for the intrinsic variability of volcanic eruptions, and implicitly assumes that inter-class size variability (i.e. size difference between different eruptive size classes) dominates over intra-class size variability (i.e. size difference within an eruptive size class), the latter of which is treated as negligible. So far, no quantitative study has been undertaken to verify such an assumption. Here, we adopt a novel Probabilistic Volcanic Hazard Analysis (PVHA) strategy, which accounts for intrinsic eruptive variabilities, to quantify the tephra fallout hazard in the Campania area. We compare the results of the new probabilistic approach with the classical scenario approach. The results allow for determining whether a simplified scenario approach can be considered valid, and for quantifying the bias which arises when full variability is not accounted for.

  14. 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

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

    PubMed

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

    2015-05-07

    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.

  16. 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.

  17. The Campanian Ignimbrite Eruption: New Data on Volcanic Ash Dispersal and Its Potential Impact on Human Evolution

    PubMed Central

    Fitzsimmons, Kathryn E.; Hambach, Ulrich; Veres, Daniel; Iovita, Radu

    2013-01-01

    The Campanian Ignimbrite (CI) volcanic eruption was the most explosive in Europe in the last 200,000 years. The event coincided with the onset of an extremely cold climatic phase known as Heinrich Event 4 (HE4) approximately 40,000 years ago. Their combined effect may have exacerbated the severity of the climate through positive feedbacks across Europe and possibly globally. The CI event is of particular interest not only to investigate the role of volcanism on climate forcing and palaeoenvironments, but also because its timing coincides with the arrival into Europe of anatomically modern humans, the demise of Neanderthals, and an associated major shift in lithic technology. At this stage, however, the degree of interaction between these factors is poorly known, based on fragmentary and widely dispersed data points. In this study we provide important new data from Eastern Europe which indicate that the magnitude of the CI eruption and impact of associated distal ash (tephra) deposits may have been substantially greater than existing models suggest. The scale of the eruption is modelled by tephra distribution and thickness, supported by local data points. CI ashfall extends as far as the Russian Plain, Eastern Mediterranean and northern Africa. However, modelling input is limited by very few data points in Eastern Europe. Here we investigate an unexpectedly thick CI tephra deposit in the southeast Romanian loess steppe, positively identified using geochemical and geochronological analyses. We establish the tephra as a widespread primary deposit, which blanketed the topography both thickly and rapidly, with potentially catastrophic impacts on local ecosystems. Our discovery not only highlights the need to reassess models for the magnitude of the eruption and its role in climatic transition, but also suggests that it may have substantially influenced hominin population and subsistence dynamics in a region strategic for human migration into Europe. PMID:23799050

  18. The Campanian Ignimbrite eruption: new data on volcanic ash dispersal and its potential impact on human evolution.

    PubMed

    Fitzsimmons, Kathryn E; Hambach, Ulrich; Veres, Daniel; Iovita, Radu

    2013-01-01

    The Campanian Ignimbrite (CI) volcanic eruption was the most explosive in Europe in the last 200,000 years. The event coincided with the onset of an extremely cold climatic phase known as Heinrich Event 4 (HE4) approximately 40,000 years ago. Their combined effect may have exacerbated the severity of the climate through positive feedbacks across Europe and possibly globally. The CI event is of particular interest not only to investigate the role of volcanism on climate forcing and palaeoenvironments, but also because its timing coincides with the arrival into Europe of anatomically modern humans, the demise of Neanderthals, and an associated major shift in lithic technology. At this stage, however, the degree of interaction between these factors is poorly known, based on fragmentary and widely dispersed data points. In this study we provide important new data from Eastern Europe which indicate that the magnitude of the CI eruption and impact of associated distal ash (tephra) deposits may have been substantially greater than existing models suggest. The scale of the eruption is modelled by tephra distribution and thickness, supported by local data points. CI ashfall extends as far as the Russian Plain, Eastern Mediterranean and northern Africa. However, modelling input is limited by very few data points in Eastern Europe. Here we investigate an unexpectedly thick CI tephra deposit in the southeast Romanian loess steppe, positively identified using geochemical and geochronological analyses. We establish the tephra as a widespread primary deposit, which blanketed the topography both thickly and rapidly, with potentially catastrophic impacts on local ecosystems. Our discovery not only highlights the need to reassess models for the magnitude of the eruption and its role in climatic transition, but also suggests that it may have substantially influenced hominin population and subsistence dynamics in a region strategic for human migration into Europe.

  19. Solar Eruptions: Coronal Mass Ejections and Flares

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2012-01-01

    This lecture introduces the topic of Coronal mass ejections (CMEs) and solar flares, collectively known as solar eruptions. During solar eruptions, the released energy flows out from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. Flares can be eruptive or confined. Eruptive flares accompany CMEs, while confined flares hav only electromagnetic signature. CMEs can drive MHD shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. CMEs heading in the direction of Earth arrive in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currnts that can disrupt power grids, railroads, and underground pipelines

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

    USGS Publications Warehouse

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

    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.

  1. Calbuco Volcano Erupts in Southern Chile

    NASA Image and Video Library

    2015-04-24

    Calbuco Volcano in southern Chile has erupted for the first time since 1972, with the last major eruption occurring in 1961 that sent ash columns 12-15 kilometers high. This image was taken by the Suomi NPP satellite's VIIRS instrument in a high resolution infrared channel around 0515Z on April 23, 2015. Credit: NOAA/NASA/NPP/VIIRS

  2. Overview of Chaitén Volcano, Chile, and its 2008-2009 eruption

    USGS Publications Warehouse

    Major, Jon J.; Lara, Luis E.

    2013-01-01

    Chaitén Volcano erupted unexpectedly in May 2008 in one of the largest eruptions globally since the 1990s. It was the largest rhyolite eruption since the great eruption of Katmai Volcano in 1912, and the first rhyolite eruption to have at least some of its aspects monitored. The eruption consisted of an approximately 2-week-long explosive phase that generated as much as 1 km3 bulk volume tephra (~0.3 km3 dense rock equivalent) followed by an approximately 20-month-long effusive phase that erupted about 0.8 km3 of high-silica rhyolite lava that formed a new dome within the volcano’s caldera. Prior to its eruption, little was known about the eruptive history of the volcano or the hazards it posed to society. This edition of Andean Geology contains a selection of papers that discuss new insights on the eruptive history of Chaitén Volcano, and the broad impacts of and new insights obtained from analyses of the 2008-2009 eruption. Here, we summarize the geographic, tectonic, and climatic setting of Chaitén Volcano and the pre-2008 state of knowledge of its eruptive history to provide context for the papers in this edition, and we provide a revised chronology of the 2008-2009 eruption.

  3. 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.

  4. Preliminary Spreadsheet of Eruption Source Parameters for Volcanoes of the World

    USGS Publications Warehouse

    Mastin, Larry G.; Guffanti, Marianne; Ewert, John W.; Spiegel, Jessica

    2009-01-01

    Volcanic eruptions that spew tephra into the atmosphere pose a hazard to jet aircraft. For this reason, the International Civil Aviation Organization (ICAO) has designated nine Volcanic Ash and Aviation Centers (VAACs) around the world whose purpose is to track ash clouds from eruptions and notify aircraft so that they may avoid these ash clouds. During eruptions, VAACs and their collaborators run volcanic-ashtransport- and-dispersion (VATD) models that forecast the location and movement of ash clouds. These models require as input parameters the plume height H, the mass-eruption rate , duration D, erupted volume V (in cubic kilometers of bubble-free or 'dense rock equivalent' [DRE] magma), and the mass fraction of erupted tephra with a particle size smaller than 63 um (m63). Some parameters, such as mass-eruption rate and mass fraction of fine debris, are not obtainable by direct observation; others, such as plume height or duration, are obtainable from observations but may be unavailable in the early hours of an eruption when VATD models are being initiated. For this reason, ash-cloud modelers need to have at their disposal source parameters for a particular volcano that are based on its recent eruptive history and represent the most likely anticipated eruption. They also need source parameters that encompass the range of uncertainty in eruption size or characteristics. In spring of 2007, a workshop was held at the U.S. Geological Survey (USGS) Cascades Volcano Observatory to derive a protocol for assigning eruption source parameters to ash-cloud models during eruptions. The protocol derived from this effort was published by Mastin and others (in press), along with a world map displaying the assigned eruption type for each of the world's volcanoes. Their report, however, did not include the assigned eruption types in tabular form. Therefore, this Open-File Report presents that table in the form of an Excel spreadsheet. These assignments are preliminary and will

  5. Does fluoride in drinking water delay tooth eruption?

    PubMed

    Jolaoso, Ismail Adeyemi; Kumar, Jayanth; Moss, Mark E

    2014-01-01

    The objectives of this study are to determine the effect of fluoride exposure on permanent tooth eruption patterns as well as to understand its effect on caries attack rate by accounting for the number of erupted tooth surfaces. We analyzed data from the 1986-1987 National Survey of Oral Health of US Schoolchildren to determine the mean number of erupted permanent teeth and permanent first molars according to fluoride level in drinking water. The analysis included 13,348 children aged 5-17 years with a history of single residence. We also estimated the attack rate (decayed, missing, and filled surfaces/surfaces at risk) for fluoride deficient, suboptimal, and optimally fluoridated areas adjusting for covariates. Multivariable statistical analyses were performed to control for potential confounders. By age 7, almost all permanent first molars had erupted. The adjusted mean number of erupted permanent first molars per child were 3.81, 3.67, and 3.92 in areas with <0.3, 0.3-<0.7, and 0.7-1.2 ppm of fluoride, respectively. The adjusted caries attack rate in the first permanent molars among 5- to 17-year-old children was 93, 81, and 78 per 1,000 surfaces in fluoride deficient, suboptimal, and optimally fluoridated areas, respectively (P < 0.0001). This pattern of higher first molar attack rate among children in the fluoride-deficient communities was also observed in all erupted teeth. Exposure to fluoride in drinking water did not delay the eruption of permanent teeth. The observed difference in dental caries experience among children exposed to different fluoride levels could not be explained by the timing of eruption of permanent teeth. © 2014 American Association of Public Health Dentistry.

  6. 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

  7. A basalt trigger for the 1991 eruptions of Pinatubo volcano?

    USGS Publications Warehouse

    Pallister, J.S.; Hoblitt, R.P.; Reyes, A.G.

    1992-01-01

    THE eruptive products of calc-alkaline volcanos often show evidence for the mixing of basaltic and acid magmas before eruption (see, for example, refs 1, 2). These observations have led to the suggestion3 that the injection of basaltic magma into the base of a magma chamber (or the catastrophic overturn of a stably stratified chamber containing basaltic magma at its base) might trigger an eruption. Here we report evidence for the mixing of basaltic and dacitic magmas shortly before the paroxysmal eruptions of Pinatubo volcano on 15 June 1991. Andesitic scoriae erupted on 12 June contain minerals and glass with disequilibrium compositions, and are considerably more mafic than the dacitic pumices erupted on 15 June. Differences in crystal abundance and glass composition among the pumices may arise from pre-heating of the dacite magma by the underlying basaltic liquid before mixing. Degassing of this basaltic magma may also have contributed to the climatologically important sulphur dioxide emissions that accompanied the Pinatubo eruptions.

  8. Magma plumbing for the 2014-2015 Holuhraun eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Geiger, Harri; Mattsson, Tobias; Deegan, Frances M.; Troll, Valentin R.; Burchardt, Steffi; Gudmundsson, Ólafur; Tryggvason, Ari; Krumbholz, Michael; Harris, Chris

    2016-08-01

    The 2014-2015 Holuhraun eruption on Iceland was located within the Askja fissure swarm but was accompanied by caldera subsidence in the Bárðarbunga central volcano 45 km to the southwest. Geophysical monitoring of the eruption identified a seismic swarm that migrated from Bárðarbunga to the Holuhraun eruption site over the course of two weeks. In order to better understand this lateral connection between Bárðarbunga and Holuhraun, we present mineral textures and compositions, mineral-melt-equilibrium calculations, whole rock and trace element data, and oxygen isotope ratios for selected Holuhraun samples. The Holuhraun lavas are compositionally similar to recorded historical eruptions from the Bárðarbunga volcanic system but are distinct from the historical eruption products of the nearby Askja system. Thermobarometry calculations indicate a polybaric magma plumbing system for the Holuhraun eruption, wherein clinopyroxene and plagioclase crystallized at average depths of ˜17 km and ˜5 km, respectively. Crystal resorption textures and oxygen isotope variations imply that this multilevel plumbing system facilitated magma mixing and assimilation of low-δ18O Icelandic crust prior to eruption. In conjunction with the existing geophysical evidence for lateral migration, our results support a model of initial vertical magma ascent within the Bárðarbunga plumbing system followed by lateral transport of aggregated magma batches within the upper crust to the Holuhraun eruption site.

  9. [Localized eruptive juvenile xanthogranuloma].

    PubMed

    Vanotti, S; Chiaverini, C; Rostain, G; Cardot-Leccia, N; Lacour, J-P

    2014-03-01

    Juvenile xanthogranuloma (JXG) is a non-Langerhans histiocytosis of young children characterized by solitary or multiple yellowish cutaneous nodules. Atypical skin lesions such as lichenoid eruptions, and pedunculated, maculopapular, plaque-like or linear lesions have been described. We report a case of eruptive XGJ en plaque in the left leg in an infant. A 13-month-old child presented asymptomatic eruptive, yellowish papules of the leg measuring 5 to 10mm since the age of 2months. There was no cutaneous infiltration between the lesions. Darier's sign was negative. Histological examination confirmed the diagnosis of JXG. The course of the disease comprised a gradual decrease in the number of active lesions with slight residual pigmentation. Our case was suggestive of JXG en plaque. Only 7 cases have been reported in the literature, all appearing before the age of 5months. The lesions corresponded mostly to an asymptomatic erythematous plaque studded with small yellowish/red nodules of variable localisation. Spontaneous involvement was noted in all cases. No systemic involvement was found. Herein we present a unique case of localised multiple JXG without evident clinical infiltrating plaque progressing with self-resolving flares. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  10. On the use of remote infrasound and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Caudron, Corentin; Taisne, Benoit; Garces, Milton

    The February 2014 eruption of Kelud volcano (Indonesia) destroyed most of the instruments near it. We use remote seismic and infrasound sensors to reconstruct the eruptive sequence. The first explosions were relatively weak seismic and infrasound events. A major stratospheric ash injection occurred a few minutes later and produced long-lasting atmospheric and ground-coupled acoustic waves that were detected as far as 11,000 km by infrasound sensors and up to 2300 km away on seismometers. A seismic event followed ~12 minutes later and was recorded 7000 km away by seismometers. We estimate a volcanic intensity around 10.9, placing the 2014 Keludmore » eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. As a result, we demonstrate how remote infrasound and seismic sensors are critical for the early detection of volcanic explosions, and how they can help to constrain and understand eruptive sequences.« less

  11. On the use of remote infrasound and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption

    DOE PAGES

    Caudron, Corentin; Taisne, Benoit; Garces, Milton; ...

    2015-07-14

    The February 2014 eruption of Kelud volcano (Indonesia) destroyed most of the instruments near it. We use remote seismic and infrasound sensors to reconstruct the eruptive sequence. The first explosions were relatively weak seismic and infrasound events. A major stratospheric ash injection occurred a few minutes later and produced long-lasting atmospheric and ground-coupled acoustic waves that were detected as far as 11,000 km by infrasound sensors and up to 2300 km away on seismometers. A seismic event followed ~12 minutes later and was recorded 7000 km away by seismometers. We estimate a volcanic intensity around 10.9, placing the 2014 Keludmore » eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. As a result, we demonstrate how remote infrasound and seismic sensors are critical for the early detection of volcanic explosions, and how they can help to constrain and understand eruptive sequences.« less

  12. UBIQUITOUS SOLAR ERUPTIONS DRIVEN BY MAGNETIZED VORTEX TUBES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.

    2013-06-10

    The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruption events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push the surrounding material up, generating shocks. Our simulations reveal complicated high-speed flow patterns andmore » thermodynamic and magnetic structure in the erupting vortex tubes. The main new results are: (1) the eruptions are initiated in the subsurface layers and are driven by high-pressure gradients in the subphotosphere and photosphere and by the Lorentz force in the higher atmosphere layers; (2) the fluctuations in the vortex tubes penetrating into the chromosphere are quasi-periodic with a characteristic period of 2-5 minutes; and (3) the eruptions are highly non-uniform: the flows are predominantly downward in the vortex tube cores and upward in their surroundings; the plasma density and temperature vary significantly across the eruptions.« less

  13. Volcan Baru: Eruptive History and Volcano-Hazards Assessment

    USGS Publications Warehouse

    Sherrod, David R.; Vallance, James W.; Tapia Espinosa, Arkin; McGeehin, John P.

    2008-01-01

    Volcan Baru is a potentially active volcano in western Panama, about 35 km east of the Costa Rican border. The volcano has had four eruptive episodes during the past 1,600 years, including its most recent eruption about 400?500 years ago. Several other eruptions occurred in the prior 10,000 years. Several seismic swarms in the 20th century and a recent swarm in 2006 serve as reminders of a restless tectonic terrane. Given this history, Volcan Baru likely will erupt again in the near or distant future, following some premonitory period of seismic activity and subtle ground deformation that may last for days or months. Future eruptions will likely be similar to past eruptions?explosive and dangerous to those living on the volcano?s flanks. Outlying towns and cities could endure several years of disruption in the wake of renewed volcanic activity. Described in this open-file report are reconnaissance mapping and stratigraphic studies, radiocarbon dating, lahar-inundation modeling, and hazard-analysis maps. Existing data have been compiled and included to make this report as comprehensive as possible. The report is prepared in coooperation with National Secretariat for Science, Technology and Innovation (SENACYT) of the Republic of Panama and the U.S. Agency for International Development (USAID).

  14. Depth of origin of magma in eruptions.

    PubMed

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

    2013-09-26

    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.

  15. Infrasonic component of volcano-seismic eruption tremor

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Fee, David

    2014-03-01

    Air-ground and ground-air elastic wave coupling are key processes in the rapidly developing field of seismoacoustics and are particularly relevant for volcanoes. During a sustained explosive volcanic eruption, it is typical to record a sustained broadband signal on seismometers, termed eruption tremor. Eruption tremor is usually attributed to a subsurface seismic source process, such as the upward migration of magma and gases through the shallow conduit and vent. However, it is now known that sustained explosive volcanic eruptions also generate powerful tremor signals in the atmosphere, termed infrasonic tremor. We investigate infrasonic tremor coupling down into the ground and its contribution to the observed seismic tremor. Our methodology builds on that proposed by Ichihara et al. (2012) and involves cross-correlation, coherence, and cross-phase spectra between waveforms from nearly collocated seismic and infrasonic sensors; we apply it to datasets from Mount St. Helens, Tungurahua, and Redoubt Volcanoes.

  16. The 18 May 1980 eruption of Mount St. Helens: The nature of the eruption, with an atmospheric perspective

    NASA Technical Reports Server (NTRS)

    Rose, W. I., Jr.; Hoffman, M. F.

    1982-01-01

    Mount St. Helens erupted somewhat less than 0.5 cu km of magma (dense rock equivalent) on May 18, 1980. The May 18 event was usually violent. As much 35% of the volume of the airfall material fell outside of the 2.5 mm isopach, which encloses about 88,000 sq km. This extraordinary dispersive power was transmitted by an eruption column which reached heights of more than 20 km. There was a lateral blast (or surge) of unusually large dimensions associated with the onset of the eruption. The magma is dacitic in composition and had a low ( 500 ppm) sulfur content. Distal ashes contain much nonmagmatic (lithic) material, but smaller ( 50 microns m) particles are mostly finely divided magmatic dacite. The grain size distributions of the ash are multimodal, frequently with peaks at 90, 25, and 10 microns. The finer populations fell out faster than their terminal velocities as simple particles would suggest. It is inferred that large proportions of the fine ash fell out as composite particles. This condition greatly reduces the atmospheric burden of silicate particles. Some of the unusual aspects (violence, intense surges, multimodal grain size distributions, lithic content of the ashes) of the eruption may be due to its phreatomagmatic character. The hydrothermal system above the magma may have infiltrated the magma body at the onset of the eruption. An "overprint" of the geochemistry of this hydrothermal system on the geochemistry of the magmatic gas system is likely. One important feature is that reduced gas species may be much more abundant than in many eruptions. Another is that fine ash may form aggregates more readily.

  17. Studying the Formation and Evolution of Eruptive Solar Magnetic Flux Ropes

    NASA Astrophysics Data System (ADS)

    Linton, M.

    2017-12-01

    Solar magnetic eruptions are dramatic sources of solar activity, and dangerous sources of space weather hazards. Many of these eruptions take the form of magnetic flux ropes, i.e., magnetic fieldlines wrapping around a core magnetic flux tube. Investigating the processes which form these flux ropes both prior to and during eruption, and investigating their evolution after eruption, can give us a critical window into understanding the sources of and processes involved in these eruptions. This presentation will discuss modeling and observational investigations into these various phases of flux rope formation, eruption, and evolution, and will discuss how these different explorations can be used to develop a more complete picture of erupting flux rope dynamics. This work is funded by the NASA Living with a Star program.

  18. Research oriented MSc course on solar eruptions

    NASA Astrophysics Data System (ADS)

    Vainio, Rami; Heber, Bernd; Agueda, Neus; Kilpua, Emilia; Isavnin, Alexey; Afanasiev, Alexandr; Ganse, Urs; Koskinen, Hannu E. J.

    2014-05-01

    Department of Physics, University of Helsinki, organized a five-credit-point Master-level course on "Solar Eruptions and Space Environment" in spring 2013. The course, attended by nine students, included twenty hours of introductory lectures on solar eruptive phenomena (focusing on energetic particle emissions) as well as experimental and theoretical methods to analyze them. In addition, the course contained ten hours of exercise sessions, where solutions on short calculation exercises were presented and discussed. The main learning method on the course was, however, a coordinated scientific analysis of five solar eruptions observed by the STEREO spacecraft in 2010-2011. The students were grouped in four teams to study the solar eruptive events from four different view points: (1) Analysis of morphology and kinematics of coronal mass ejections, (2) analysis of EUV imaging observations of coronal wave-like transients, (3) solar and interplanetary magnetic field conditions during the eruptions, and (4) emission and transport modelling of near-relativistic electron events associated with the eruptions. Each group of students was assigned a scientist to oversee their work. The students reported weekly on their progress and gave a final presentation (of 30 minutes) in a seminar session at the end of the seven-week course. Grading of the course was based on the home exercises and final presentations. Students were also asked to give anonymous feedback on the course. Learning results on the course were very encouraging, showing that research oriented courses with practical research exercises on specific topics give students deeper knowledge and more practical skills than traditional lectures and home exercises alone.

  19. Magmatic densities control erupted volumes in Icelandic volcanic systems

    NASA Astrophysics Data System (ADS)

    Hartley, Margaret; Maclennan, John

    2018-04-01

    Magmatic density and viscosity exert fundamental controls on the eruptibility of magmas. In this study, we investigate the extent to which magmatic physical properties control the eruptibility of magmas from Iceland's Northern Volcanic Zone (NVZ). By studying subaerial flows of known age and volume, we are able to directly relate erupted volumes to magmatic physical properties, a task that has been near-impossible when dealing with submarine samples dredged from mid-ocean ridges. We find a strong correlation between magmatic density and observed erupted volumes on the NVZ. Over 85% of the total volume of erupted material lies close to a density and viscosity minimum that corresponds to the composition of basalts at the arrival of plagioclase on the liquidus. These magmas are buoyant with respect to the Icelandic upper crust. However, a number of small-volume eruptions with densities greater than typical Icelandic upper crust are also found in Iceland's neovolcanic zones. We use a simple numerical model to demonstrate that the eruption of magmas with higher densities and viscosities is facilitated by the generation of overpressure in magma chambers in the lower crust and uppermost mantle. This conclusion is in agreement with petrological constraints on the depths of crystallisation under Iceland.

  20. Postglacial eruptive history of the Western Volcanic Zone, Iceland

    NASA Astrophysics Data System (ADS)

    Sinton, John; GröNvold, Karl; SæMundsson, KristjáN.

    2005-12-01

    New field observations, age constraints, and extensive chemical analyses define the complete postglacial eruptive history of the 170-km-long Western Volcanic Zone (WVZ) of Iceland, the ultraslow-spreading western boundary of the south Iceland microplate. We have identified 44 separate eruptive units, 10 of which are small-volume eruptions associated with the flanking Grímsnes system. Overall chemical variations are consistent with very simplified models of melting of a source approximating primitive mantle composition. The 17 eruptions in the first 3000 years of postglacial time account for about 64% of the total postglacial production and are incompatible-element depleted compared to younger units, consistent with enhanced melting as a consequence of rebound immediately following deglaciation. Steadily declining eruption rates for the last 9000 years also correlate with changes in average incompatible element ratios that appear to reflect continued decline in melting extents to the present day. This result is not restricted to the WVZ, however, and may herald a decline in melting throughout all of western Iceland during later postglacial time. Lavas from the northern part of the WVZ are depleted in incompatible elements relative to those farther south at all times, indicating either a long-wavelength gradient in mantle source composition or variations in the melting process along axis. We find no evidence in the postglacial volcanic record for current failure of the WVZ, despite evidence for continued propagation of the eastern margin of the microplate. The dominance of lava shields in the eruptive history of the WVZ contrasts with the higher number of fissure eruptions in other Icelandic volcanic zones. WVZ shields represent long-duration, low-effusion rate eruptions fed by recharge magma arising out of the mantle. Average effusion rate is the key variable distinguishing shield and fissure eruptions, both within the WVZ and between different volcanic zones. High

  1. Proximal lava drainage controls on basaltic fissure eruption dynamics

    NASA Astrophysics Data System (ADS)

    Jones, T. J.; Llewellin, E. W.; Houghton, B. F.; Brown, R. J.; Vye-Brown, C.

    2017-11-01

    Hawaiian basaltic eruptions commonly initiate as a fissure, producing fountains, spattering, and clastogenic lava flows. Most fissures rapidly localize to form a small number of eruptive vents, the location of which may influence the subsequent distribution of lava flows and associated hazards. We present results from a detailed field investigation of the proximal deposits of episode 1 of the 1969 fissure eruption of Mauna Ulu, Kīlauea, Hawai`i. Exceptional preservation of the deposits allows us to reconstruct vent-proximal lava drainage patterns and to assess the role that drainage played in constraining vent localization. Through detailed field mapping, including measurements of the height and internal depth of lava tree moulds, we reconstruct high-resolution topographic maps of the pre-eruption ground surface, the lava high-stand surface and the post-eruption ground surface. We calculate the difference in elevation between pairs of maps to estimate the lava inundation depth and lava drainage depth over the field area and along different segments of fissure. Aerial photographs collected during episode 1 of the eruption allow us to locate those parts of the fissure that are no longer exposed at the surface. By comparing with the inundation and drainage maps, we find that fissure segments that were inundated with lava to greater depths (typically 1-6 m) during the eruption later became foci of lava drainage back into the fissure (internal drain-back). We infer that, in these areas, lava ponding over the fissure suppressed discharge of magma, thereby favouring drain-back and stagnation. By contrast, segments with relatively shallow inundation (typically less than 1 m), such as where the fissure intersects pre-eruptive topographic highs, or where flow away from the vent (outflow) was efficient, are often associated with sub-circular vent geometries in the post-eruption ground surface. We infer that these parts of the fissure became localization points for ongoing

  2. The association between childhood obesity and tooth eruption.

    PubMed

    Must, Aviva; Phillips, Sarah M; Tybor, David J; Lividini, Keith; Hayes, Catherine

    2012-10-01

    Obesity is a growth-promoting process as evidenced by its effect on the timing of puberty. Although studies are limited, obesity has been shown to affect the timing of tooth eruption. Both the timing and sequence of tooth eruption are important to overall oral health. The purpose of this study was to examine the association between obesity and tooth eruption. Data were combined from three consecutive cycles (2001-2006) of the National Health and Nutrition Examination Survey (NHANES) and analyzed to examine associations between the number of teeth erupted (NET) and obesity status (BMI z-score >95th percentile BMI relative to the Centers for Disease Control and Prevention (CDC) growth reference) among children 5 up to 14 years of age, controlling for potential confounding by age, gender, race, and socioeconomic status (SES). Obesity is significantly associated with having a higher average NET during the mixed dentition period. On average, teeth of obese children erupted earlier than nonobese children with obese children having on average 1.44 more teeth erupted than nonobese children, after adjusting for age, gender, and race/ethnicity (P < 0.0001). SES was not a confounder of the observed associations. Obese children, on average, have significantly more teeth erupted than nonobese children after adjusting for gender, age, and race. These findings may have clinical importance in the area of dental and orthodontic medicine both in terms of risk for dental caries due to extended length of time exposed in the oral cavity and sequencing which may increase the likelihood of malocclusions.

  3. The Association Between childhood Obesity and Tooth Eruption

    PubMed Central

    Must, Aviva; Phillips, Sarah M.; Tybor, David J.; Lividini, Keith; Hayes, Catherine

    2013-01-01

    Obesity is a growth-promoting process as evidenced by its effect on the timing of puberty. Although studies are limited, obesity has been shown to affect the timing of tooth eruption. Both the timing and sequence of tooth eruption are important to overall oral health. The purpose of this study was to examine the association between obesity and tooth eruption. Data were combined from three consecutive cycles (2001–2006) of the National Health and Nutrition Examination Survey (NHANES) and analyzed to examine associations between the number of teeth erupted (NET) and obesity status (BMI z-score >95th percentile BMI relative to the Centers for Disease Control and Prevention (CDC) growth reference) among children 5 up to 14 years of age, controlling for potential confounding by age, gender, race, and socioeconomic status (SES). Obesity is significantly associated with having a higher average NET during the mixed dentition period. On average, teeth of obese children erupted earlier than nonobese children with obese children having on average 1.44 more teeth erupted than nonobese children, after adjusting for age, gender, and race/ethnicity (P < 0.0001). SES was not a confounder of the observed associations. Obese children, on average, have significantly more teeth erupted than nonobese children after adjusting for gender, age, and race. These findings may have clinical importance in the area of dental and orthodontic medicine both in terms of risk for dental caries due to extended length of time exposed in the oral cavity and sequencing which may increase the likelihood of malocclusions. PMID:22310231

  4. Mortality in England during the 1783 4 Laki Craters eruption

    NASA Astrophysics Data System (ADS)

    Witham, C. S.; Oppenheimer, C.

    2004-12-01

    1783/4 has been recognised as a mortality “crisis year” in the population history of England. This demographic incident coincides with the Laki Craters eruption, Iceland, which began in June 1783 and fumigated many parts of Europe with volcanic gases and particles. Many reports and proxy climate records implicate the volcanic cloud in meteorological anomalies, including notably hot 1783 summer conditions in England and a severe subsequent winter. We present here a detailed analysis of the geographical and temporal trends in English mortality data, and interpret them in the light of the climatological records and observations of the pollutant cloud. We show that there were two distinct crisis periods: in August-September 1783, and January-February 1784, which together accounted for ~20,000 extra deaths. In both cases, the East of England was the worst affected region. Possible causes for the two crisis periods are considered and we conclude that the timing and magnitude of the winter mortality peak can be explained by the severe cold of January 1784. The late summer mortality followed 1 2 months after the very hot July of 1783 and may also have been related to the weather, with the time lag reflecting the relatively slow spread of enteric disease or the contraction of malaria. However, it is hard to explain the entire late summer anomaly by these high temperature causes. We therefore consider that fine acid aerosol and/or gases in the volcanic haze may also have contributed to the unusual August-September mortality. Given that complex radiative and dynamical effects of the volcanic cloud are implicated in the climatic anomalies in 1783 4, it is likely that the Laki Craters eruption did play a role in the English mortality crises of the same period.

  5. The 2011 Eruption of the Recurrent Nova T Pyxidis: The Discovery, the Pre-eruption Rise, the Pre-eruption Orbital Period, and the Reason for the Long Delay

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.; Landolt, Arlo U.; Linnolt, Michael; Stubbings, Rod; Pojmanski, Grzegorz; Plummer, Alan; Kerr, Stephen; Nelson, Peter; Carstens, Rolf; Streamer, Margaret; Richards, Tom; Myers, Gordon; Dillon, William G.

    2013-08-01

    We report the discovery by M. Linnolt on JD 2,455,665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova), and with high time resolution in three filters. The speed of the rise peaked at 9 mag day-1, while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report the discovery by R. Stubbings of a pre-eruption rise starting 18 days before the eruption, peaking 1.1 mag brighter than its long-time average, and then fading back toward quiescence 4 days before the eruption. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB) anticipatory rise closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to 2011 February, where the orbital period is fast increasing with P/\\dot{P}=+313{,000} yr. From 2008 to 2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622950 ± 0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of (1.7-3.5) × 10-7 M ⊙ yr-1. We report 6116 magnitudes between 1890 and 2011, for an average B = 15.59 ± 0.01 from 1967 to 2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. The ultraviolet-optical-infrared spectral energy distribution is well fit by a power law with f νvpropν1.0, although the narrow ultraviolet region has a tilt with a fit of f νvpropν1/3. We prove that most of the T Pyx light is not coming from a disk, or any superposition of blackbodies, but rather is coming from some nonthermal source. We confirm the extinction measure from IUE with E(B - V) = 0.25 ± 0.02 mag.

  6. THE 2011 ERUPTION OF THE RECURRENT NOVA T PYXIDIS: THE DISCOVERY, THE PRE-ERUPTION RISE, THE PRE-ERUPTION ORBITAL PERIOD, AND THE REASON FOR THE LONG DELAY

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schaefer, Bradley E.; Landolt, Arlo U.; Linnolt, Michael

    We report the discovery by M. Linnolt on JD 2,455,665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova), and with high time resolution in three filters. The speed of the rise peaked at 9 mag day{sup -1}, while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report themore » discovery by R. Stubbings of a pre-eruption rise starting 18 days before the eruption, peaking 1.1 mag brighter than its long-time average, and then fading back toward quiescence 4 days before the eruption. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB) anticipatory rise closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to 2011 February, where the orbital period is fast increasing with P/ P-dot =+313,000 yr. From 2008 to 2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622950 {+-} 0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of (1.7-3.5) Multiplication-Sign 10{sup -7} M{sub Sun} yr{sup -1}. We report 6116 magnitudes between 1890 and 2011, for an average B = 15.59 {+-} 0.01 from 1967 to 2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. The ultraviolet-optical-infrared spectral energy distribution is well fit by a power law with f{sub {nu}}{proportional_to}{nu}{sup 1.0}, although the narrow ultraviolet region has a tilt with a fit of f{sub {nu}}{proportional_to}{nu}{sup 1/3}. We prove that most of the T Pyx light is not coming from a disk, or any superposition of blackbodies, but rather is coming from some

  7. Monitoring and Modeling: The Future of Volcanic Eruption Forecasting

    NASA Astrophysics Data System (ADS)

    Poland, M. P.; Pritchard, M. E.; Anderson, K. R.; Furtney, M.; Carn, S. A.

    2016-12-01

    Eruption forecasting typically uses monitoring data from geology, gas geochemistry, geodesy, and seismology, to assess the likelihood of future eruptive activity. Occasionally, months to years of warning are possible from specific indicators (e.g., deep LP earthquakes, elevated CO2 emissions, and aseismic deformation) or a buildup in one or more monitoring parameters. More often, observable changes in unrest occur immediately before eruption, as magma is rising toward the surface. In some cases, little or no detectable unrest precedes eruptive activity. Eruption forecasts are usually based on the experience of volcanologists studying the activity, but two developing fields offer a potential leap beyond this practice. First, remote sensing data, which can track thermal, gas, and ash emissions, as well as surface deformation, are increasingly available, allowing statistically significant research into the characteristics of unrest. For example, analysis of hundreds of volcanoes indicates that deformation is a more common pre-eruptive phenomenon than thermal anomalies, and that most episodes of satellite-detected unrest are not immediately followed by eruption. Such robust datasets inform the second development—probabilistic models of eruption potential, especially those that are based on physical-chemical models of the dynamics of magma accumulation and ascent. Both developments are essential for refining forecasts and reducing false positives. For example, many caldera systems have not erupted but are characterized by unrest that, in another context, would elicit strong concern from volcanologists. More observations of this behavior and better understanding of the underlying physics of unrest will improve forecasts of such activity. While still many years from implementation as a forecasting tool, probabilistic physio-chemical models incorporating satellite data offer a complement to expert assessments that, together, can form a powerful forecasting approach.

  8. Utility of patch testing for patients with drug eruption.

    PubMed

    Ohtoshi, S; Kitami, Y; Sueki, H; Nakada, T

    2014-04-01

    Patch testing is less dangerous than oral provocation testing for identification of the causative drug for patients with drug eruption; however, its usefulness for such identification is controversial. To clarify the rates of positive patch testing for patients with drug eruption, classified by causative drugs and clinical features. We analysed results during the period 1990-2010 for 444 patients (151 men, 293 women; mean ± SD age 49.9 ± 18.6 years) who were tested for drug eruption. In the patient group, there were 309 people (69.1%) with maculopapular eruption and 31 (6.9%) with severe drug eruption. The test materials were applied to the back and left for 2 days under occlusion, then results were assessed by the International Contact Dermatitis Research Group (ICDRG) scoring system 3 days after application. Reactions of + to +++ were regarded as positive. Of the 444 patients, 100 (22.4%) had a positive patch test result to a suspected drug. Positive rates were 23.6% and 20.0% for maculopapular eruption and fixed drug eruption, respectively. The class of materials to which most patients reacted positively was contrast medium (n = 53; 41.1%), followed by drugs acting on the central nervous system (n = 18; 28.6%). In the latter group, 16 of the 18 patients were positive to antiepileptics. Positive rates depend on the causative drug rather than the clinical features of the drug eruption. Patch testing is useful when contrast medium or antiepileptics are suspected to be the causative drugs. However, standardization of patch test materials and method of reading is needed, as well as guidelines regarding when testing should be performed. Although patch testing for drug eruption has significant potential, it requires further validation. © 2014 The Authors. Clinical and Experimental Dermatology published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.

  9. Juvenile pumice and pyroclastic obsidian reveal the eruptive conditions necessary for the stability of Plinian eruption of rhyolitic magma

    NASA Astrophysics Data System (ADS)

    Giachetti, T.; Shea, T.; Gonnermann, H. M.; McCann, K. A.; Hoxsie, E. C.

    2016-12-01

    Significant explosive activity generally precedes or coexists with the large effusion of rhyolitic lava (e.g., Mono Craters; Medicine Lake Volcano; Newberry; Chaitén; Cordón Caulle). Such explosive-to-effusive transitions and, ultimately, cessation of activity are commonly explained by the overall waning magma chamber pressure accompanying magma withdrawal, albeit modulated by magma outgassing. The tephra deposits of such explosive-to-effusive eruptions record the character of the transition - abrupt or gradual - as well as potential changes in eruptive conditions, such as magma composition, volatiles content, mass discharge rate, conduit size, magma outgassing. Results will be presented from a detailed study of both the gas-rich (pumice) and gas-poor (obsidian) juvenile pyroclasts produced during the Plinian phase of the 1060 CE Glass Mountain eruption of Medicine Lake Volcano, California. In the proximal deposits, a multitude of pumice-rich sections separated by layers rich in dense clasts suggests a pulsatory behavior of the explosive phase. Density measurements on 2,600 pumices show that the intermediate, most voluminous deposits have a near constant median porosity of 65%. However, rapid increase in porosity to 75-80% is observed at both the bottom and the top of the fallout deposits, suggestive of rapid variations in magma degassing. In contrast, a water content of pyroclastic obsidians of approximately 0.6 wt% does remain constant throughout the eruption, suggesting that the pyroclastic obsidians degassed up to a constant pressure of a few megapascals. Numerical modeling of eruptive magma ascent and degassing is used to provide constraints on eruption conditions.

  10. Impacts of high-latitude volcanic eruptions on ENSO and AMOC.

    PubMed

    Pausata, Francesco S R; Chafik, Leon; Caballero, Rodrigo; Battisti, David S

    2015-11-10

    Large volcanic eruptions can have major impacts on global climate, affecting both atmospheric and ocean circulation through changes in atmospheric chemical composition and optical properties. The residence time of volcanic aerosol from strong eruptions is roughly 2-3 y. Attention has consequently focused on their short-term impacts, whereas the long-term, ocean-mediated response has not been well studied. Most studies have focused on tropical eruptions; high-latitude eruptions have drawn less attention because their impacts are thought to be merely hemispheric rather than global. No study to date has investigated the long-term effects of high-latitude eruptions. Here, we use a climate model to show that large summer high-latitude eruptions in the Northern Hemisphere cause strong hemispheric cooling, which could induce an El Niño-like anomaly, in the equatorial Pacific during the first 8-9 mo after the start of the eruption. The hemispherically asymmetric cooling shifts the Intertropical Convergence Zone southward, triggering a weakening of the trade winds over the western and central equatorial Pacific that favors the development of an El Niño-like anomaly. In the model used here, the specified high-latitude eruption also leads to a strengthening of the Atlantic Meridional Overturning Circulation (AMOC) in the first 25 y after the eruption, followed by a weakening lasting at least 35 y. The long-lived changes in the AMOC strength also alter the variability of the El Niño-Southern Oscillation (ENSO).

  11. Requirement of alveolar bone formation for eruption of rat molars

    PubMed Central

    Wise, Gary E.; He, Hongzhi; Gutierrez, Dina L.; Ring, Sherry; Yao, Shaomian

    2011-01-01

    Tooth eruption is a localized event that requires a dental follicle (DF) to regulate the resorption of alveolar bone to form an eruption pathway. During the intra-osseous phase of eruption, the tooth moves through this pathway. The mechanism or motive force that propels the tooth through this pathway is controversial but many studies have shown that alveolar bone growth at the base of the crypt occurs during eruption. To determine if this bone growth (osteogenesis) was causal, experiments were designed in which the expression of an osteogenic gene in the DF, bone morphogenetic protein-6 (BMP6), was inhibited by injection of the 1st mandibular molar of the rat with an siRNA targeted against BMP6. The injection was followed by electroporation to promote uptake of the siRNA. In 45 first molars injected, eruption either was delayed or completely inhibited (7 molars). In the impacted molars, an eruption pathway formed but bone growth at the base of the crypt was greatly reduced as compared to the erupted first molar controls. These studies show that alveolar bone growth at the base of the crypt is required for tooth eruption and that BMP6 may be an essential gene for promoting this growth. PMID:21896048

  12. National-level long-term eruption forecasts by expert elicitation

    NASA Astrophysics Data System (ADS)

    Bebbington, Mark S.; Stirling, Mark W.; Cronin, Shane; Wang, Ting; Jolly, Gill

    2018-06-01

    Volcanic hazard estimation is becoming increasingly quantitative, creating the potential for land-use decisions and engineering design to use volcanic information in an analogous manner to seismic codes. The initial requirement is to characterize the possible hazard sources, quantifying the likely timing, magnitude and location of the next eruption in each case. This is complicated by the extremely different driving processes at individual volcanoes, and incomplete and uneven records of past activity at various volcanoes. To address these issues, we carried out an expert elicitation approach to estimate future eruption potential for 12 volcanoes of interest in New Zealand. A total of 28 New Zealand experts provided estimates that were combined using Cooke's classical method to arrive at a hazard estimate. In 11 of the 12 cases, the elicited eruption duration increased with VEI, and was correlated with expected repose, differing little between volcanoes. Most of the andesitic volcanoes had very similar elicited distributions for the VEI of a future eruption, except that Taranaki was expected to produce a larger eruption, due to the current long repose. Elicited future vent locations for Tongariro and Okataina reflect strongly the most recent eruptions. In the poorly studied Bay of Islands volcanic field, the estimated vent location distribution was centred on the centroid of the previous vent locations, while in the Auckland field, it was focused on regions within the field without past eruptions. The elicited median dates for the next eruptions ranged from AD2022 (Whakaari/White Island) to AD4390 (Tuhua/Mayor Island).

  13. 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

  14. Modeling Volcanic Eruption Parameters by Near-Source Internal Gravity Waves.

    PubMed

    Ripepe, M; Barfucci, G; De Angelis, S; Delle Donne, D; Lacanna, G; Marchetti, E

    2016-11-10

    Volcanic explosions release large amounts of hot gas and ash into the atmosphere to form plumes rising several kilometers above eruptive vents, which can pose serious risk on human health and aviation also at several thousands of kilometers from the volcanic source. However the most sophisticate atmospheric models and eruptive plume dynamics require input parameters such as duration of the ejection phase and total mass erupted to constrain the quantity of ash dispersed in the atmosphere and to efficiently evaluate the related hazard. The sudden ejection of this large quantity of ash can perturb the equilibrium of the whole atmosphere triggering oscillations well below the frequencies of acoustic waves, down to much longer periods typical of gravity waves. We show that atmospheric gravity oscillations induced by volcanic eruptions and recorded by pressure sensors can be modeled as a compact source representing the rate of erupted volcanic mass. We demonstrate the feasibility of using gravity waves to derive eruption source parameters such as duration of the injection and total erupted mass with direct application in constraining plume and ash dispersal models.

  15. Modeling Volcanic Eruption Parameters by Near-Source Internal Gravity Waves

    PubMed Central

    Ripepe, M.; Barfucci, G.; De Angelis, S.; Delle Donne, D.; Lacanna, G.; Marchetti, E.

    2016-01-01

    Volcanic explosions release large amounts of hot gas and ash into the atmosphere to form plumes rising several kilometers above eruptive vents, which can pose serious risk on human health and aviation also at several thousands of kilometers from the volcanic source. However the most sophisticate atmospheric models and eruptive plume dynamics require input parameters such as duration of the ejection phase and total mass erupted to constrain the quantity of ash dispersed in the atmosphere and to efficiently evaluate the related hazard. The sudden ejection of this large quantity of ash can perturb the equilibrium of the whole atmosphere triggering oscillations well below the frequencies of acoustic waves, down to much longer periods typical of gravity waves. We show that atmospheric gravity oscillations induced by volcanic eruptions and recorded by pressure sensors can be modeled as a compact source representing the rate of erupted volcanic mass. We demonstrate the feasibility of using gravity waves to derive eruption source parameters such as duration of the injection and total erupted mass with direct application in constraining plume and ash dispersal models. PMID:27830768

  16. Eruptive Keratoacanthomas Associated With Pembrolizumab Therapy

    PubMed Central

    Freites-Martinez, Azael; Kwong, Bernice Y.; Rieger, Kerri E.; Coit, Daniel G.; Colevas, A. Dimitrios; Lacouture, Mario E.

    2017-01-01

    IMPORTANCE To our knowledge, there have been no previous reports of eruptive keratoacanthomas (KAs) in patients receiving pembrolizumab. OBJECTIVE To report the cases of 3 consecutive patients with pembrolizumab-induced eruptive KAs and their management. DESIGN, SETTING, AND PARTICIPANTS Case report study of 3 patients from 2 centers with pembrolizumab-treated cancer who all developed eruptive KAs. INTERVENTIONS All 3 patients had AK treatment with clobetasol ointment and intralesional triamcinolone; 2 patients also underwent open superficial cryosurgery. RESULTS Three consecutive patients with cancer, 2 men and 1 woman (median age, 83 years; range 77–91 years), experienced pembrolizumab-associated eruptive KAs. All patients presented with a sudden onset of multiple lesions on sun-exposed areas of their extremities after a median of 13 months (range, 4–18 months) of pembrolizumab therapy. On lesional biopsy, a lichenoid infiltrate was observed in the underlying dermis, predominantly composed of CD3+ T cells, scattered CD20+ B cells, and relatively few PD-1+ (programmed cell death 1–positive) T cells, an immunophenotypic pattern also observed in other cases of anti–PD-1–induced lichenoid dermatitis. Patients were treated with clobetasol ointment and intralesional triamcinolone, alone or in combination with open superficial cryosurgery. All KAs resolved in all patients, and no new lesions occurred during close follow-up. Pembrolizumab treatment was continued without disruption in all 3 cases, and all patients had complete responses of their primary cancers. CONCLUSIONS AND RELEVANCE Pembrolizumab is used in advanced melanoma, advanced non–small-cell lung cancer, and in head and neck cancer. A variety of dermatologic immune-related adverse events including maculopapular eruption, lichenoid reactions, pruritus, and vitiligo have been described. This case series demonstrates that pembrolizumab therapy may also be associated with eruptive KAs with

  17. Evaluation of Kilauea Eruptions By Using Stable Isotope Analysis

    NASA Astrophysics Data System (ADS)

    Rahimi, K. E.; Bursik, M. I.

    2016-12-01

    Kilauea, on the island of Hawaii, is a large volcanic edifice with numerous named vents scattered across its surface. Halema`uma`u crater sits with Kilauea caldera, above the magma reservoir, which is the main source of lava feeding most vents on Kilauea volcano. Halema`uma`u crater produces basaltic explosive activity ranging from weak emission to sub-Plinian. Changes in the eruption style are thought to be due to the interplay between external water and magma (phreatomagmatic/ phreatic), or to segregation of gas from magma (magmatic) at shallow depths. Since there are three different eruption mechanisms (phreatomagmatic, phreatic, and magmatic), each eruption has its own isotope ratios. The aim of this study is to evaluate the eruption mechanism by using stable isotope analysis. Studying isotope ratios of D/H and δ18O within fluid inclusion and volcanic glass will provide an evidence of what driven the eruption. The results would be determined the source of water that drove an eruption by correlating the values with water sources (groundwater, rainwater, and magmatic water) since each water source has a diagnostic value of D/H and δ18O. These results will provide the roles of volatiles in eruptions. The broader application of this research is that these methods could help volcanologists forecasting and predicting the current volcanic activity by mentoring change in volatiles concentration within deposits.

  18. 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

  19. 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

  20. Sixty thousand years of magmatic volatile history before the caldera-forming eruption of Mount Mazama, Crater Lake, Oregon

    USGS Publications Warehouse

    Wright, Heather M.; Bacon, Charles R.; Vazquez, Jorge A.; Sisson, Thomas W.

    2012-01-01

    The well-documented eruptive history of Mount Mazama, Oregon, provides an excellent opportunity to use pre-eruptive volatile concentrations to study the growth of an explosive silicic magmatic system. Melt inclusions (MI) hosted in pyroxene and plagioclase crystals from eight dacitic–rhyodacitic eruptive deposits (71–7.7 ka) were analyzed to determine variations in volatile-element concentrations and changes in magma storage conditions leading up to and including the climactic eruption of Crater Lake caldera. Temperatures (Fe–Ti oxides) increased through the series of dacites, then decreased, and increased again through the rhyodacites (918–968 to ~950 to 845–895 °C). Oxygen fugacity began at nickel–nickel-oxide buffer (NNO) +0.8 (71 ka), dropped slightly to NNO +0.3, and then climbed to its highest value with the climactic eruption (7.7 ka) at NNO +1.1 log units. In parallel with oxidation state, maximum MI sulfur concentrations were high early in the eruptive sequence (~500 ppm), decreased (to ~200 ppm), and then increased again with the climactic eruption (~500 ppm). Maximum MI sulfur correlates with the Sr content (as a proxy for LREE, Ba, Rb, P2O5) of recharge magmas, represented by basaltic andesitic to andesitic enclaves and similar-aged lavas. These results suggest that oxidized Sr-rich recharge magmas dominated early and late in the development of the pre-climactic dacite–rhyodacite system. Dissolved H2O concentrations in MI do not, however, correlate with these changes in dominant recharge magma, instead recording vapor solubility relations in the developing shallow magma storage and conduit region. Dissolved H2O concentrations form two populations through time: the first at 3–4.6 wt% (with a few extreme values up to 6.1 wt%) and the second at ≤2.4 wt%. CO2 concentrations measured in a subset of these inclusions reach up to 240 ppm in early-erupted deposits (71 ka) and are below detection in climactic deposits (7.7 ka). Combined H2O and

  1. Volcanoes in the Classroom: Simulating an Eruption Column

    NASA Astrophysics Data System (ADS)

    Harpp, K. S.; Geist, D. J.; Koleszar, A. M.

    2005-12-01

    Few students have the opportunity to witness volcanic eruptions first hand. Analog models of eruptive processes provide ways for students to apply basic physical principles when field observations are not feasible. We describe a safe simulation of violent volcanic explosions, one that can be carried out simply and easily as a demonstration for specialized volcanology classes, introductory classes, and science outreach programs. Volcanic eruptions are fundamentally gas-driven phenomena. Depressurization of volatiles dissolved in magma during ascent is the driving force behind most explosive eruptions. We have developed a demonstration whereby the instructor can initiate a gas-driven eruption, which produces a dramatic but safe explosion and eruptive column. First, one pours liquid nitrogen into a weighted, plastic soda bottle, which is then sealed and placed into a trashcan filled with water. As the liquid nitrogen boils, the pressure inside the bottle increases until the seal fails, resulting in an explosion. The expansive force propels a column of water vertically, to 10 or more meters. Students can operate the demonstration themselves and carry out a sequence of self-designed variations, changing the vent size and viscosity of the "magma", for instance. They can also vary the material used as "tephra", studying the effects of projectile density, column height, and wind direction on tephra distribution. The physical measurements that students collect, such as column height and tephra radius, can be used as the basis for problem sets that explore the dynamics of eruption columns. Possible calculations include ejection velocity, the pressure needed to propel the water column, and average vesicularity of the "magma". Students can then compare their results to observations from real volcanic eruptions. We find this to be an exceedingly effective demonstration of gas-driven liquid explosions and one that is safe if done properly. [NOTE: Please do NOT attempt this

  2. Effects of Volcanic Eruptions on Stratospheric Ozone Recovery

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.

    2002-01-01

    The effects of the stratospheric sulfate aerosol layer associated with the Mt. Pinatubo volcano and future volcanic eruptions on the recovery of the ozone layer is studied with an interactive two-dimensional photochemical model. The time varying chlorine loading and the stratospheric cooling due to increasing carbon dioxide have been taken into account. The computed ozone and temperature changes associated with the Mt. Pinatubo eruption in 1991 agree well with observations. Long model runs out to the year 2050 have been carried out, in which volcanoes having the characteristics of the Mount Pinatubo volcano were erupted in the model at 10-year intervals starting in the year 2010. Compared to a non-volcanic run using background aerosol loading, transient reductions of globally averaged column ozone of 2-3 percent were computed as a result of each of these eruptions, with the ozone recovering to that computed for the non-volcanic case in about 5 years after the eruption. Computed springtime Arctic column ozone losses of from 10 to 18 percent also recovered to the non-volcanic case within 5 years. These results suggest that the long-term recovery of ozone would not be strongly affected by infrequent volcanic eruptions with a sulfur loading approximating Mt. Pinatubo. Sensitivity studies in which the Arctic lower stratosphere was forced to be 4 K and 10 K colder resulted in transient ozone losses of which also recovered to the non-volcanic case in 5 years. A case in which a volcano five times Mt. Pinatubo was erupted in the year 2010 led to maximum springtime column ozone losses of 45 percent which took 10 years to recover to the background case. Finally, in order to simulate a situation in which frequent smaller volcanic eruptions result in increasing the background sulfate loading, a simulation was made in which the background aerosol was increased by 10 percent per year. This resulted in a delay of the recovery of column ozone to 1980 values of more than 10 years.

  3. 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

  4. Terbinafine-induced lichenoid drug eruption.

    PubMed

    Zheng, Yue; Zhang, Jie; Chen, Haiyan; Lai, Wei; Maibach, Howard I

    2017-03-01

    Drug-induced lichen planus has been induced by antibiotics, anticonvulsants, antidiabetics, antimalarials, antitubercular drugs, antihypertensives, psychiatric drugs, chemotherapeutic agents, diuretic, heavy metals, NSAIDs, etc. Terbinafine, an antifungal agent, is widely used for dermatophyte infections and onychomycosis. Cutaneous adverse effects of terbinafine are rarely reported. Here, we report a case of terbinafine-induced lichenoid drug eruption in a 22-year-old who presented with generalized lichenoid eruption 2 weeks after terbinafine initiation of. The body and lip cleared completely after 8 weeks of drug withdrawal; nail change cleared after 12 weeks.

  5. The first permanent molar: spontaneous eruption after a five-year failure.

    PubMed

    Mistry, Vinay N; Barker, Christopher S; James Spencer, R

    2017-09-01

    It is rare for a first permanent molar (FPM) to temporarily exhibit clinical features of failure of eruption, followed by regeneration of full eruptive capacity 5 years later. Indeterminate failure of eruption (IFE) is a diagnosis of exclusion where the distinction between primary failure of eruption (PFE) and mechanical failure of eruption (MFE) is unclear, including patients too young to specify. An 11-year-old girl attended the orthodontic clinic at Mid Yorkshire Hospitals NHS Trust regarding an unerupted lower right FPM. Her medical and dental trauma history was unremarkable. She presented with a Class II division 2 malocclusion in the mixed dentition, with all other FPMs fully erupted. This report documents that an unerupted FPM in an 11-year-old patient may still have the eruptive potential to become functional within the dentition. The period spent monitoring the FPM's outcome prior to surgical intervention has avoided an operation under general anaesthetic and potentially unnecessary orthodontic treatment, as the tooth subsequently erupted without treatment. © 2017 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. The Variable Climate Impact of Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Graf, H.

    2011-12-01

    The main effect of big volcanic eruptions in the climate system is due to their efficient transport of condensable gases and their precursors into the stratosphere. There the formation of aerosols leads to effects on atmospheric radiation transfer inducing a reduction of incoming solar radiation by reflection (i.e. cooling of the Earth surface) and absorption of near infrared radiation (i.e. heating) in the aerosol laden layers. In the talk processes determining the climate effect of an eruption will be illustrated by examples, mainly from numerical modelling. The amount of gases released from a magma during an eruption and the efficiency of their transport into very high altitudes depends on the geological setting (magma type) and eruption style. While mid-sized eruption plumes of Plinian style quickly can develop buoyancy by entrainment of ambient air, very large eruptions with high magma flux rates often tend to collapsing plumes and co-ignimbrite style. These cover much bigger areas and are less efficient in entraining ambient air. Vertical transport in these plumes is chaotic and less efficient, leading to lower neutral buoyancy height and less gas and particles reaching high stratospheric altitudes. Explosive energy and amount of released condensable gases are not the only determinants for the climatic effect of an eruption. The effect on shortwave radiation is not linear with the amount of aerosols formed since according to the Lambert-Beer Law atmospheric optical depth reaches a saturation limit with increased absorber concentration. In addition, if more condensable gas is available for aerosol growth, particles become larger and this affects their optical properties to less reflection and more absorption. Larger particles settle out faster, thus reducing the life time of the aerosol disturbance. Especially for big tropical eruptions the strong heating of the stratosphere in low latitudes leads to changes in atmospheric wave propagation by strengthened

  7. Eruption of Eyjafjallajökull Volcano, Iceland

    NASA Image and Video Library

    2010-03-27

    NASA Image acquired March 24, 2010 To learn more and to download a high res version of this image go here: earthobservatory.nasa.gov/IOTD/view.php?id=43252 Iceland’s Eyjafjallajökull Volcano burst into life for the first time in 190 years on March 20, 2010. A 500-meter- (2,000-foot) long fissure opened in the Fimmvörduháls pass to the west of the ice-covered summit of Eyjafjallajökull. Lava fountains erupted fluid magma, which quickly built several hills of bubble-filled lava rocks (scoria) along the vent. A lava flow spread northeast, spilling into Hrunagil Gully. This natural-color satellite image shows lava fountains, lava flows, a volcanic plume, and steam from vaporized snow. The image was acquired on March 24, 2010, by the Advanced Land Imager (ALI) aboard NASA’s Earth Observing-1 (EO-1) satellite. The lava fountains are orange-red, barely visible at the 10-meter (33-foot) resolution of the satellite. The scoria cones surrounding the fissure are black, as is the lava flow extending to the northeast. White volcanic gases escape from the vent and erupting lava, while a steam plume rises where the hot lava meets snow. (The bright green color along the edge of the lava flow is an artifact of the sensor.) The eruption of Eyjafjallajökull was presaged by a series of earthquakes starting in early March. Over time, the earthquakes rose towards the surface, and land near the volcano rose at least 40 millimeters (2 inches)—both indications that magma was moving underneath the volcano. The eruption continued through at least March 26th, and may continue for several more months. Previous eruptions in the area have caused flooding due to the melting of glacial ice (a Jökulhlaup), but the current eruption is in an area covered by winter snow, not permanent ice. Although some past eruptions of Eyjafjallajökull were followed by larger, explosive eruptions at nearby Katla Volcano, there is currently no sign of activity at Katla. NASA image by Robert Simmon, using

  8. Evolution of the magma feeding system during a Plinian eruption: The case of Pomici di Avellino eruption of Somma-Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Massaro, S.; Costa, A.; Sulpizio, R.

    2018-01-01

    The current paradigm for volcanic eruptions is that magma erupts from a deep magma reservoir through a volcanic conduit, typically modelled with fixed rigid geometries such as cylinders. This simplistic view of a volcanic eruption does not account for the complex dynamics that usually characterise a large explosive event. Numerical simulations of magma flow in a conduit combined with volcanological and geological data, allow for the first description of a physics-based model of the feeding system evolution during a sustained phase of an explosive eruption. The method was applied to the Plinian phase of the Pomici di Avellino eruption (PdA, 3945 ±10 cal yr BP) from Somma-Vesuvius (Italy). Information available from volcanology, petrology, and lithology studies was used as input data and as constraints for the model. In particular, Mass Discharge Rates (MDRs) assessed from volcanological methods were used as target values for numerical simulations. The model solutions, which are non-unique, were constrained using geological and volcanological data, such as volume estimates and types of lithic components in the fall deposits. Three stable geometric configurations of the feeding system (described assuming elliptical cross-section of variable dimensions) were assessed for the Eruptive Units 2 and 3 (EU2, EU3), which form the magmatic Plinian phase of PdA eruption. They describe the conduit system geometry at time of deposition of EU2 base, EU2 top, and EU3. A 7-km deep dyke (length 2 a = 200-4 00 m, width 2 b = 10- 12 m), connecting the magma chamber to the surface, characterised the feeding system at the onset of the Plinian phase (EU2 base). The feeding system rapidly evolved into hybrid geometric configuration, with a deeper dyke (length 2 a = 600- 800 m, width 2 b = 50 m) and a shallower cylindrical conduit (diameter D = 50 m, dyke-to-cylinder transition depth ∼2100 m), during the eruption of the EU2 top. The deeper dyke reached the dimensions of 2 a = 2000 m and

  9. Pyroclast textural variation as an indicator of eruption column steadiness in andesitic Plinian eruptions at Mt. Ruapehu

    USGS Publications Warehouse

    Pardo, Natalia; Cronin, Shane J.; Wright, Heather M.N.; Schipper, C. Ian; Smith, Ian; Stewart, Bob

    2014-01-01

    Between 27 and 11 cal. ka BP, a transition is observed in Plinian eruptions at Mt. Ruapehu, indicating evolution from non-collapsing (steady and oscillatory) eruption columns to partially collapsing columns (both wet and dry). To determine the causes of these variations over this eruptive interval, we examined lapilli fall deposits from four eruptions representing the climactic phases of each column type. All eruptions involve andesite to basaltic andesite magmas containing plagioclase, clinopyroxene, orthopyroxene and magnetite phenocrysts. Differences occur in the dominant pumice texture, the degree of bulk chemistry and textural variability, the average microcrystallinity and the composition of groundmass glass. In order to investigate the role of ascent and degassing processes on column stability, vesicle textures were quantified by gas volume pycnometry (porosity), X-ray synchrotron and computed microtomography (μ-CT) imagery from representative clasts from each eruption. These data were linked to groundmass crystallinity and glass geochemistry. Pumice textures were classified into six types (foamy, sheared, fibrous, microvesicular, microsheared and dense) according to the vesicle content, size and shape and microlite content. Bulk porosities vary from 19 to 95 % among all textural types. Melt-referenced vesicle number density ranges between 1.8 × 102 and 8.9 × 102 mm−3, except in fibrous textures, where it spans from 0.3 × 102 to 53 × 102 mm−3. Vesicle-free magnetite number density varies within an order of magnitude from 0.4 × 102 to 4.5 × 102 mm−3 in samples with dacitic groundmass glass and between 0.0 and 2.3 × 102 mm−3 in samples with rhyolitic groundmass. The data indicate that columns that collapsed to produce pyroclastic flows contained pumice with the greatest variation in bulk composition (which overlaps with but extends to slightly more silicic compositions than other eruptive products); textures

  10. Ectopic eruption of first permanent molars: presenting features and associations.

    PubMed

    Mooney, G C; Morgan, A G; Rodd, H D; North, S

    2007-09-01

    To investigate presenting features of ectopically erupting first permanent molars and associations with other dental anomalies. Prospective convenience study. 28 panoral radiographs were collected, over a 24-month period, of 7-11 year-old children with radiographic evidence of ectopic eruption of first permanent molars who presented to a Dental Teaching Hospital in the North of England. A further 20 radiographs were collected of matched patients with no evidence of ectopic molar eruption. All radiographs were analysed under standard conditions to record the distribution and type of ectopic eruption (if present). In addition, the presence of the following dental anomalies was noted: cleft lip and/or palate; supernumerary teeth; hypodontia, and infraocclusion of primary molars. Chi-squared analysis was performed to determine any significant differences in the frequency of these dental anomalies between ectopic molar and control groups. For patients with ectopic molar eruption, the majority demonstrated ectopic eruption of either one or two first permanent molars (32% and 57% of subjects respectively). There were a similar proportion of 'jumps' and 'holds'. 92% of these were maxillary teeth and there was equal left and right distribution. Interestingly, a positive record of ectopic eruption was only documented in the dental records of 35.7% of these subjects. Children with ectopic eruption were significantly more likely to have at least one additional dental anomaly than was the case for the control group (60.7% versus 25%). Notably, primary molar infraocclusion and cleft lip/palate were significantly more frequent in the ectopic group. This study, the first in a British population, has identified a significant association between ectopic eruption of first permanent molars and other dental anomalies. A multifactorial aetiology is thus supported and clinicians should be alert to the co-existence of ectopic eruption and other dental anomalies.

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

    PubMed

    Gudmundsson, Gunnar; Larsen, Guðrun

    2016-01-01

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

  12. Numerical models of volcanic eruption plumes: inter-comparison and sensitivity

    NASA Astrophysics Data System (ADS)

    Costa, Antonio; Suzuki, Yujiro; Folch, Arnau; Cioni, Raffaello

    2016-10-01

    The accurate description of the dynamics of convective plumes developed during explosive volcanic eruptions represents one of the most crucial and intriguing challenges in volcanology. Eruptive plume dynamics are significantly affected by complex interactions with the surrounding atmosphere, in the case of both strong eruption columns, rising vertically above the tropopause, and weak volcanic plumes, developing within the troposphere and often following bended trajectories. The understanding of eruptive plume dynamics is pivotal for estimating mass flow rates of volcanic sources, a crucial aspect for tephra dispersion models used to assess aviation safety and tephra fallout hazard. For these reasons, several eruption column models have been developed in the past decades, including the more recent sophisticated computational fluid dynamic models.

  13. Coronal Bright Points Associated with Minifilament Eruptions

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 109 cm-3. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  14. 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

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang Jiayan; Jiang Yunchun; Zheng Ruisheng

    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 eruptionmore » 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.« less

  16. MeMoVolc report on classification and dynamics of volcanic explosive eruptions

    NASA Astrophysics Data System (ADS)

    Bonadonna, C.; Cioni, R.; Costa, A.; Druitt, T.; Phillips, J.; Pioli, L.; Andronico, D.; Harris, A.; Scollo, S.; Bachmann, O.; Bagheri, G.; Biass, S.; Brogi, F.; Cashman, K.; Dominguez, L.; Dürig, T.; Galland, O.; Giordano, G.; Gudmundsson, M.; Hort, M.; Höskuldsson, A.; Houghton, B.; Komorowski, J. C.; Küppers, U.; Lacanna, G.; Le Pennec, J. L.; Macedonio, G.; Manga, M.; Manzella, I.; Vitturi, M. de'Michieli; Neri, A.; Pistolesi, M.; Polacci, M.; Ripepe, M.; Rossi, E.; Scheu, B.; Sulpizio, R.; Tripoli, B.; Valade, S.; Valentine, G.; Vidal, C.; Wallenstein, N.

    2016-11-01

    Classifications of volcanic eruptions were first introduced in the early twentieth century mostly based on qualitative observations of eruptive activity, and over time, they have gradually been developed to incorporate more quantitative descriptions of the eruptive products from both deposits and observations of active volcanoes. Progress in physical volcanology, and increased capability in monitoring, measuring and modelling of explosive eruptions, has highlighted shortcomings in the way we classify eruptions and triggered a debate around the need for eruption classification and the advantages and disadvantages of existing classification schemes. Here, we (i) review and assess existing classification schemes, focussing on subaerial eruptions; (ii) summarize the fundamental processes that drive and parameters that characterize explosive volcanism; (iii) identify and prioritize the main research that will improve the understanding, characterization and classification of volcanic eruptions and (iv) provide a roadmap for producing a rational and comprehensive classification scheme. In particular, classification schemes need to be objective-driven and simple enough to permit scientific exchange and promote transfer of knowledge beyond the scientific community. Schemes should be comprehensive and encompass a variety of products, eruptive styles and processes, including for example, lava flows, pyroclastic density currents, gas emissions and cinder cone or caldera formation. Open questions, processes and parameters that need to be addressed and better characterized in order to develop more comprehensive classification schemes and to advance our understanding of volcanic eruptions include conduit processes and dynamics, abrupt transitions in eruption regime, unsteadiness, eruption energy and energy balance.

  17. Volcanic Thunder From Explosive Eruptions at Bogoslof Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Haney, Matthew M.; Van Eaton, Alexa R.; Lyons, John J.; Kramer, Rebecca L.; Fee, David; Iezzi, Alexandra M.

    2018-04-01

    Lightning often occurs during ash-producing eruptive activity, and its detection is now being used in volcano monitoring for rapid alerts. We report on infrasonic and sonic recordings of the related, but previously undocumented, phenomenon of volcanic thunder. We observe volcanic thunder during the waning stages of two explosive eruptions at Bogoslof volcano, Alaska, on a microphone array located 60 km away. Thunder signals arrive from a different direction than coeruptive infrasound generated at the vent following an eruption on 10 June 2017, consistent with locations from lightning networks. For the 8 March 2017 eruption, arrival times and amplitudes of high-frequency thunder signals correlate well with the timing and strength of lightning detections. In both cases, the thunder is associated with lightning that continues after significant eruptive activity has ended. Infrasonic and sonic observations of volcanic thunder offer a new avenue for studying electrification processes in volcanic plumes.

  18. Geometry of the September 1971 eruptive fissure at Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Dvorak, J.J.

    1990-01-01

    A three-dimensional model has been used to estimate the location and dimensions of the eruptive fissure for the 24-29 September 1971 eruption along the southwest rift zone of Kilauea volcano, Hawaii. The model is an inclined rectangular sheet embedded in an elastic half-space with constant displacement on the plane of the sheet. The set of "best" model parameters suggests that the sheet is vertical, extends from a depth of about 2 km to the surface, and has a length of about 14 km. Because this sheet intersects the surface where eruptive vents and extensive ground cracking formed during the eruption, this sheet probably represents the conduit for erupted lava. The amount of displacement perpendicular to the sheet is about 1.9 m, in the middle range of values measured for the amount of opening across the September 1971 eruptive fissure. The thickness of the eruptive fissure associated with the January 1983 east rift zone eruption was determined in an earlier paper to be 3.6 m, about twice the thickness determined here for the September 1971 eruption. Because the lengths (12 km for 1983 and 14 km for 1971) and heights (about 2 km) of the sheet models derived for the January 1983 and September 1971 rift zone eruptions are nearly identical, the greater thickness for the January 1983 eruptive fissure implies that the magma pressure was about a factor of two greater to form the January 1983 eruptive fissure. Because the September 1971 and January 1983 eruptive fissures extent to depths of only a few kilometers, the region of greatest compressive stress produced along the volcano's flank by either of these eruptive fissures would also be within a few kilometers of the surface. Previous work has shown that rift eruptions and intrusions contribute to the buildup of compressive stress along Kilauea's south flank and that this buildup is released by increased seismicity along the south flank. Because south flank earthquakes occur at significantly greater depths, i.e., from 5

  19. On a Possible Unified Scaling Law for Volcanic Eruption Durations

    PubMed Central

    Cannavò, Flavio; Nunnari, Giuseppe

    2016-01-01

    Volcanoes constitute dissipative systems with many degrees of freedom. Their eruptions are the result of complex processes that involve interacting chemical-physical systems. At present, due to the complexity of involved phenomena and to the lack of precise measurements, both analytical and numerical models are unable to simultaneously include the main processes involved in eruptions thus making forecasts of volcanic dynamics rather unreliable. On the other hand, accurate forecasts of some eruption parameters, such as the duration, could be a key factor in natural hazard estimation and mitigation. Analyzing a large database with most of all the known volcanic eruptions, we have determined that the duration of eruptions seems to be described by a universal distribution which characterizes eruption duration dynamics. In particular, this paper presents a plausible global power-law distribution of durations of volcanic eruptions that holds worldwide for different volcanic environments. We also introduce a new, simple and realistic pipe model that can follow the same found empirical distribution. Since the proposed model belongs to the family of the self-organized systems it may support the hypothesis that simple mechanisms can lead naturally to the emergent complexity in volcanic behaviour. PMID:26926425

  20. On a Possible Unified Scaling Law for Volcanic Eruption Durations.

    PubMed

    Cannavò, Flavio; Nunnari, Giuseppe

    2016-03-01

    Volcanoes constitute dissipative systems with many degrees of freedom. Their eruptions are the result of complex processes that involve interacting chemical-physical systems. At present, due to the complexity of involved phenomena and to the lack of precise measurements, both analytical and numerical models are unable to simultaneously include the main processes involved in eruptions thus making forecasts of volcanic dynamics rather unreliable. On the other hand, accurate forecasts of some eruption parameters, such as the duration, could be a key factor in natural hazard estimation and mitigation. Analyzing a large database with most of all the known volcanic eruptions, we have determined that the duration of eruptions seems to be described by a universal distribution which characterizes eruption duration dynamics. In particular, this paper presents a plausible global power-law distribution of durations of volcanic eruptions that holds worldwide for different volcanic environments. We also introduce a new, simple and realistic pipe model that can follow the same found empirical distribution. Since the proposed model belongs to the family of the self-organized systems it may support the hypothesis that simple mechanisms can lead naturally to the emergent complexity in volcanic behaviour.

  1. Discovery of the Largest Historic Silicic Submarine Eruption

    NASA Astrophysics Data System (ADS)

    Carey, Rebecca J.; Wysoczanski, Richard; Wunderman, Richard; Jutzeler, Martin

    2014-05-01

    It was likely twice the size of the renowned Mount St. Helens eruption of 1980 and perhaps more than 10 times bigger than the more recent 2010 Eyjafjallajökull eruption in Iceland. However, unlike those two events, which dominated world news headlines, in 2012 the daylong submarine silicic eruption at Havre volcano in the Kermadec Arc, New Zealand (Figure 1a; ~800 kilometers north of Auckland, New Zealand), passed without fanfare. In fact, for a while no one even knew it had occurred.

  2. Geostationary satellite observations of the april 1979 soufriere eruptions.

    PubMed

    Krueger, A F

    1982-06-04

    Infrared images from the geostationary satellite SMS-1 were used to study the growth of the eight major eruptions of Soufriere, St. Vincent, during April 1979. These eruptions differed considerably in growth and intensity, the most intense being that of 17 April which formed an ash cloud of 96,000 square kilometers in 4 hours. The weakest eruption formed a cloud of only 16,000 square kilometers.

  3. Volcanoes drive climate variability by emitting ozone weeks before eruptions, by forming lower stratospheric aerosols, by causing sustained ozone depletion, and by causing rapid changes in regional ozone concentrations affecting temperature and pressure differences driving atmospheric oscillations

    NASA Astrophysics Data System (ADS)

    Ward, P. L.

    2016-12-01

    Total column ozone observed by satellite on February 19, 2010, increased 75% in a plume from Eyjafjallajökull volcano in southern Iceland eastward past Novaya Zemlya, extending laterally from northern Greenland to southern Norway (http://youtu.be/wJFZcPEfoR4). Contemporaneous ground deformation and rapidly increasing numbers of earthquakes imply magma began rising from a sill 4-6 km below the volcano, erupting a month later. Whether the ozone formed from the magma or from very hot gases rising through cracks in the ground is unclear. On February 20-22, 1991, similar increases in ozone were observed north of Pinatubo volcano before its initial eruption on April 2 (http://youtu.be/5y1PU2Qu3ag). Annual average total column ozone during the year of most moderate to large explosive volcanic eruptions since routine observations of ozone began in 1927 has been substantially higher than normal. Increased total column ozone absorbs more solar ultraviolet-B radiation, warming the ozone layer and cooling Earth. Most major volcanic eruptions form sulfuric-acid aerosols in the lower part of the ozone layer providing aqueous surfaces on which heterogeneous chemical reactions enhance ozone depletion. Within a year, aerosol droplets grew large enough to reflect and scatter high-frequency solar radiation, cooling Earth 0.5oC for 2-3 years. Temperature anomalies in the northern hemisphere rose 0.7oC in 28 years from 1970 to 1998 (HadCRUT4), while annual average ozone at Arosa dropped 27 DU because of manufactured CFC gases. Beginning in August 2014, temperature anomalies in the northern hemisphere rose another 0.6oC in less than two years apparently because of the 6-month eruption of Bárðarbunga volcano in central Iceland, the highest rate of basaltic lava extrusion since 1783. Large extrusions of basaltic lava are typically contemporaneous with the greatest periods of warming throughout Earth history. Ozone concentrations at Arosa change by season typically from 370 DU during

  4. NASA Spacecraft Views Erupting Chilean Volcano

    NASA Image and Video Library

    2015-03-13

    On March 3, 2015, Chile's Villarrica volcano erupted, forcing the evacuation of thousands of people. The eruption deposited a layer of ash over the volcano's eastern slope, blanketing and darkening the normal winter snow cover. The eruption and its effects were captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft on March 9. Black flows on the other flanks are mud and ash flows. Vegetation is displayed in red colors. The thermal infrared image shows hot spots (white colored) at the summit crater, indicating continuing volcanic activity. The ash blanket is warmer (brighter) than the cold snow (black). The image covers an area of 13.5 by 16.5 kilometers, and is located at 39.4 degrees south, 71.9 degrees west. http://photojournal.jpl.nasa.gov/catalog/PIA19241

  5. Frequent eruptions of Mount Rainier over the last ˜2,600 years

    NASA Astrophysics Data System (ADS)

    Sisson, T. W.; Vallance, J. W.

    2009-08-01

    Field, geochronologic, and geochemical evidence from proximal fine-grained tephras, and from limited exposures of Holocene lava flows and a small pyroclastic flow document ten-12 eruptions of Mount Rainier over the last 2,600 years, contrasting with previously published evidence for only 11-12 eruptions of the volcano for all of the Holocene. Except for the pumiceous subplinian C event of 2,200 cal year BP, the late-Holocene eruptions were weakly explosive, involving lava effusions and at least two block-and-ash pyroclastic flows. Eruptions were clustered from ˜2,600 to ˜2,200 cal year BP, an interval referred to as the Summerland eruptive period that includes the youngest lava effusion from the volcano. Thin, fine-grained tephras are the only known primary volcanic products from eruptions near 1,500 and 1,000 cal year BP, but these and earlier eruptions were penecontemporaneous with far-traveled lahars, probably created from newly erupted materials melting snow and glacial ice. The most recent magmatic eruption of Mount Rainier, documented geochemically, was the 1,000 cal year BP event. Products from a proposed eruption of Mount Rainier between AD 1820 and 1854 (X tephra of Mullineaux (US Geol Surv Bull 1326:1-83, 1974)) are redeposited C tephra, probably transported onto young moraines by snow avalanches, and do not record a nineteenth century eruption. We found no conclusive evidence for an eruption associated with the clay-rich Electron Mudflow of ˜500 cal year BP, and though rare, non-eruptive collapse of unstable edifice flanks remains as a potential hazard from Mount Rainier.

  6. Frequent eruptions of Mount Rainier over the last ∼2,600 years

    USGS Publications Warehouse

    Sisson, T.W.; Vallance, J.W.

    2009-01-01

    Field, geochronologic, and geochemical evidence from proximal fine-grained tephras, and from limited exposures of Holocene lava flows and a small pyroclastic flow document ten–12 eruptions of Mount Rainier over the last 2,600 years, contrasting with previously published evidence for only 11–12 eruptions of the volcano for all of the Holocene. Except for the pumiceous subplinian C event of 2,200 cal year BP, the late-Holocene eruptions were weakly explosive, involving lava effusions and at least two block-and-ash pyroclastic flows. Eruptions were clustered from ∼2,600 to ∼2,200 cal year BP, an interval referred to as the Summerland eruptive period that includes the youngest lava effusion from the volcano. Thin, fine-grained tephras are the only known primary volcanic products from eruptions near 1,500 and 1,000 cal year BP, but these and earlier eruptions were penecontemporaneous with far-traveled lahars, probably created from newly erupted materials melting snow and glacial ice. The most recent magmatic eruption of Mount Rainier, documented geochemically, was the 1,000 cal year BP event. Products from a proposed eruption of Mount Rainier between AD 1820 and 1854 (X tephra of Mullineaux (US Geol Surv Bull 1326:1–83, 1974)) are redeposited C tephra, probably transported onto young moraines by snow avalanches, and do not record a nineteenth century eruption. We found no conclusive evidence for an eruption associated with the clay-rich Electron Mudflow of ∼500 cal year BP, and though rare, non-eruptive collapse of unstable edifice flanks remains as a potential hazard from Mount Rainier.

  7. Mauna Loa eruptive history—The preliminary radiocarbon record

    NASA Astrophysics Data System (ADS)

    Lockwood, John P.

    Radiocarbon dating of charcoal from beneath lava flows of Mauna Loa has provided the most detailed prehistoric eruptive chronology of any volcano on Earth. Three hundred and fifty-five 14C dates have been reviewed, stratigraphically contradictory dates have been rejected, and multiple dates on single flows averaged to give "reliable" ages on 170 separate lava flows (about 35% of the total number of prehistoric Mauna Loa flows mapped to date). The distribution of these ages has revealed fundamental variations in the time and place of Mauna Loa eruptive activity, particularly for Holocene time. As lava flow activity from Mauna Loa's summit waxes, activity on the rift zones wanes. A cyclic model is proposed which involves a period of concentrated summit shield-building activity associated with long-lived lava lakes and frequent overflows of pahoehoe lavas on the north and southeast flanks. At this time, compressive stresses across Mauna Loa's rift zones are relatively high, inhibiting eruptions in these areas. This period is then followed by a relaxation of stresses across Mauna Loa's rift zones and a long period of frequent rift zone eruptions as magma migrates downrift. This change of eruptive style is marked by summit caldera collapse (possibly associated with massive eruptions of picritic lavas low on the rift zones). Concurrent with this increased rift zone activity, the summit caldera is gradually filled by repeated summit eruptions, stress across the rift zones increases, magma rises more easily to the summit, rift activity wanes, and the cycle repeats itself. Two such cycles are suggested within the late Holocene, each lasting 1,500-2,000 years. Earlier evidence for such cycles is obscure. Mauna Loa appears to have been quiescent between 6-7 ka, for unknown reasons. A period of increased eruptive activity marked the period 8-11 ka, coincident with the Pleistocene-Holocene boundary. Other volcanoes on the Island of Hawaii for which (limited) radiocarbon dating

  8. Hydrogeomorphic responses to explosive volcanic eruptions-what have we learned?

    NASA Astrophysics Data System (ADS)

    Major, J. J.

    2011-12-01

    Explosive eruptions can greatly alter landscape hydrology and geomorphology. Analyses of hydrogeomorphic responses to four major eruptions, spanning two orders of magnitude in eruption volume, reveal patterns in the timing, pace, and style of landscape response to explosive eruptions. Tephra fall can blanket broad swaths of landscape with sediment having a low-permeability surface, and can cause significant tree damage. Volcanic blasts can also deposit many tens of cm of fines-capped sediment across the landscape, and can raze or completely remove vast tracts of forest. Debris avalanches, pyroclastic flows, and lahars can fill channels and valley floors with meters to tens of meters of gravelly sand for tens of kilometers from source; straighten, smooth or obliterate channel planforms; and remove, bury, or smother riparian vegetation. Such disturbances can radically alter runoff regimes and the manner in which water is routed along channels. Surface-infiltration capacities of landscapes denuded by volcanic blast and pyroclastic flows following eruptions of Mount St. Helens (MSH) and Unzen were reduced 1-2 orders of magnitude (from >100 mm/hr to as little as 2-5 mm/hr). Altered hydrologic processes promoted substantial overland flow in basins normally dominated by subsurface flow; measurements at Unzen showed overland flow 3-5 times greater from barren, tephra-covered ground compared to vegetated ground. Hydrological analysis at MSH showed that post-eruption wet-season peakflow discharges increased by a few to tens of percent in eruption-affected basins. Changes in hydrological processes alter sediment erosion and transport; extensive hillslope and channel erosion can lead to sediment yields that exceed preeruption yields by orders of magnitude. Indeed, sediment yields from volcanically disturbed watersheds rival those of great sediment-producing rivers worldwide. Short-term landscape-denudation rates following explosive eruptions are typically 10-104 times greater

  9. Plasma Brightenings in a Failed Solar Filament Eruption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Y.; Ding, M. D., E-mail: yingli@nju.edu.cn

    Failed filament eruptions are solar eruptions that are not associated with coronal mass ejections. In a failed filament eruption, the filament materials usually show some ascending and falling motions as well as generating bright EUV emissions. Here we report a failed filament eruption (SOL2016-07-22) that occurred in a quiet-Sun region observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory . In this event, the filament spreads out but gets confined by the surrounding magnetic field. When interacting with the ambient magnetic field, the filament material brightens up and flows along the magnetic field lines through the coronamore » to the chromosphere. We find that some materials slide down along the lifting magnetic structure containing the filament and impact the chromosphere, and through kinetic energy dissipation, cause two ribbon-like brightenings in a wide temperature range. There is evidence suggesting that magnetic reconnection occurs between the filament magnetic structure and the surrounding magnetic fields where filament plasma is heated to coronal temperatures. In addition, thread-like brightenings show up on top of the erupting magnetic fields at low temperatures, which might be produced by an energy imbalance from a fast drop of radiative cooling due to plasma rarefaction. Thus, this single event of a failed filament eruption shows the existence of a variety of plasma brightenings that may be caused by completely different heating mechanisms.« less

  10. Volcanic Eruptions of the EPR and Ridge Axis Segmentation: An Interdisciplinary View

    NASA Astrophysics Data System (ADS)

    White, S.; Soule, S. A.; Tolstoy, M.; Waldhauser, F.; Rubin, K.

    2008-12-01

    The eruption of the EPR in 2005-06 provides an ideal window into the relationship between fine-scale segmentation of the ridge axis and individual eruptive episodes. Lava flow mapping of the eruption by visual and acoustic images, precise dates on multiple eruptive units, stress information from seismicity, long-term records of hydrothermal activity, and well known segment boundaries illustrate the relationships between eruptions and segmentation of mid-ocean ridges. Lava flows emerged from several sections of the axial summit trough (AST) during the eruption, presumably from en echelon fissures between 9 45'N and 9 57'N. Each en echelon fissure is a 4th order segment, and the overall area matches the 3rd Order segment between ~9 45'N and ~9 58'N. Within the eruption, the primary eruptive fissure jumped east by 600 m at 9 53'N, and ran along an inward facing fault scarp, although limited lava effusion also extended northward along the axial fissure. A zone of high seismicity connects the normal fault bounding the eastern fissure eruption with the main locus of eruption on the ridge axis to the south, suggesting that the offset eruption may have occurred in response to stress buildup on this fault. Radiometric ages indicate that the entire along-axis extent of the eruptive fissures activated initially, but that volcanic activity focused to a single fourth-order segment within 1-3 months. Previously indentified breaks in the AST and its overall outline were largely unchanged by the eruption. These observations support the hypothesis that fourth-order segments are offsets controlled by the mechanics of dike emplacement, whereas third-order segments represent discrete volcanic systems. Dike segmentation may be controlled by variations in underlying ridge structure or the magma reservoir. Hydrothermal systems disrupted as far south as 9 37'N may be responding to cracking due to stress interaction or share a common deeper magmatic source. Comparisons between the 1991 EPR

  11. Seismic evolution of the 1989-1990 eruption sequence of Redoubt Volcano, Alaska

    USGS Publications Warehouse

    Power, J.A.; Lahr, J.C.; Page, R.A.; Chouet, B.A.; Stephens, C.D.; Harlow, D.H.; Murray, T.L.; Davies, J.N.

    1994-01-01

    Redoubt Volcano in south-central Alaska erupted between December 1989 and June 1990 in a sequence of events characterized by large tephra eruptions, pyroclastic flows, lahars and debris flows, and episodes of dome growth. The eruption was monitored by a network of five to nine seismic stations located 1 to 22 km from the summit crater. Notable features of the eruption seismicity include : (1) small long-period events beginning in September 1989 which increased slowly in number during November and early December; (2) an intense swarm of long-period events which preceded the initial eruptions on December 14 by 23 hours; (3) shallow swarms (0 to 3 km) of volcano-tectonic events following each eruption on December 15; (4) a persistent cluster of deep (6 to 10 km) volcano-tectonic earthquakes initiated by the eruptions on December 15, which continued throughout and beyond the eruption; (5) an intense swarm of long-period events which preceded the eruptions on January 2; and (6) nine additional intervals of increased long-period seismicity each of which preceded a tephra eruption. Hypocenters of volcano-tectonic earthquakes suggest the presence of a magma source region at 6-10 km depth. Earthquakes at these depths were initiated by the tephra eruptions on December 15 and likely represent the readjustment of stresses in the country rock associated with the removal of magma from these depths. The locations and time-history of these earthquakes coupled with the eruptive behavior of the volcano suggest this region was the source of most of the erupted material during the 1989-1990 eruption. This source region appears to be connected to the surface by a narrow pipe-like conduit as inferred from the hypocenters of volcano-tectonic earthquakes. Concentrations of shallow volcano-tectonic earthquakes followed each of the tephra eruptions on December 15; these shocks may represent stress readjustment in the wall rock related to the removal of magma and volatiles at these depths

  12. Measuring the speed of magma ascent during explosive eruptions of Kilauea, Hawaii

    NASA Astrophysics Data System (ADS)

    Ferguson, D. J.; Ruprecht, P.; Plank, T. A.; Hauri, E. H.; Gonnermann, H. M.; Houghton, B. F.; Swanson, D. A.

    2014-12-01

    The size and intensity of volcanic eruptions is controlled by a combination of the physical properties of magmas and the conditions of magma ascent. At basaltic volcanoes, where relatively fluid magmas are erupted, sustained explosive eruptions vary widely in style, from Hawaiian fountains erupted 10s to 100s of meter high to large Plinian type events, involving >20 km high eruption plumes. Decompression of magmas leads to volatile saturation and bubble growth, however it remains disputed how the dynamics of shallow ascent and degassing might control this disparate eruptive behaviour, or whether factors such as the initial volatile content exert the primary control on eruption style. A key issue is that the physical conditions of magma ascent, which may significantly impact eruptive dynamics, remain largely unconstrained by observational data. Here we quantify two primary variables - decompression rates and volatile contents - for magmas from three contrasting eruptions of Kīlauea volcano, Hawaii, using microanalysis and modelling of volatile diffusion along small melt tubes or embayments found in olivine crystals carried by the ascending magmas. During ascent decreasing solubility causes dissolved volatiles to diffuse along the embayment towards growing bubbles at the crystal edge. By modelling the diffusion of H2O, CO2 and S we obtain decompression rates, and indirectly ascent velocities, for the rising magma. For Hawaiian style fountaining events we obtain ascent rates of 0.05-0.07 MPa s-1 (~1 m s-1), whereas for a more intense subplinian eruption we obtain a notably faster rate of 0.29 MPa s-1 (>10m s-1). The timescales of melt transport from the storage region during these eruptions varied from around 3 to 40 minutes. We find no link between pre-eruptive volatile contents and eruption intensity, rather our results suggest that the eventual size of sustained explosive basaltic eruptions is likely governed by factors affecting the ascent velocity of melts in

  13. Global monsoon precipitation responses to large volcanic eruptions.

    PubMed

    Liu, Fei; Chai, Jing; Wang, Bin; Liu, Jian; Zhang, Xiao; Wang, Zhiyuan

    2016-04-11

    Climate variation of global monsoon (GM) precipitation involves both internal feedback and external forcing. Here, we focus on strong volcanic forcing since large eruptions are known to be a dominant mechanism in natural climate change. It is not known whether large volcanoes erupted at different latitudes have distinctive effects on the monsoon in the Northern Hemisphere (NH) and the Southern Hemisphere (SH). We address this issue using a 1500-year volcanic sensitivity simulation by the Community Earth System Model version 1.0 (CESM1). Volcanoes are classified into three types based on their meridional aerosol distributions: NH volcanoes, SH volcanoes and equatorial volcanoes. Using the model simulation, we discover that the GM precipitation in one hemisphere is enhanced significantly by the remote volcanic forcing occurring in the other hemisphere. This remote volcanic forcing-induced intensification is mainly through circulation change rather than moisture content change. In addition, the NH volcanic eruptions are more efficient in reducing the NH monsoon precipitation than the equatorial ones, and so do the SH eruptions in weakening the SH monsoon, because the equatorial eruptions, despite reducing moisture content, have weaker effects in weakening the off-equatorial monsoon circulation than the subtropical-extratropical volcanoes do.

  14. Global link between deformation and volcanic eruption quantified by satellite imagery.

    PubMed

    Biggs, J; Ebmeier, S K; Aspinall, W P; Lu, Z; Pritchard, M E; Sparks, R S J; Mather, T A

    2014-04-03

    A key challenge for volcanological science and hazard management is that few of the world's volcanoes are effectively monitored. Satellite imagery covers volcanoes globally throughout their eruptive cycles, independent of ground-based monitoring, providing a multidecadal archive suitable for probabilistic analysis linking deformation with eruption. Here we show that, of the 198 volcanoes systematically observed for the past 18 years, 54 deformed, of which 25 also erupted. For assessing eruption potential, this high proportion of deforming volcanoes that also erupted (46%), together with the proportion of non-deforming volcanoes that did not erupt (94%), jointly represent indicators with 'strong' evidential worth. Using a larger catalogue of 540 volcanoes observed for 3 years, we demonstrate how this eruption-deformation relationship is influenced by tectonic, petrological and volcanic factors. Satellite technology is rapidly evolving and routine monitoring of the deformation status of all volcanoes from space is anticipated, meaning probabilistic approaches will increasingly inform hazard decisions and strategic development.

  15. The 1984 Mauna Loa eruption and planetary geolgoy

    NASA Technical Reports Server (NTRS)

    Moore, Henry J.

    1987-01-01

    In planetary geology, lava flows on the Moon and Mars are commonly treated as relatively simple systems. Some of the complexities of actual lava flows are illustrated using the main flow system of the 1984 Mauna Loa eruption. The outline, brief narrative, and results given are based on a number of sources. The implications of the results to planetary geology are clear. Volume flow rates during an eruption depend, in part, on the volatile content of the lava. These differ from the volume flow rates calculated from post eruption flow dimensions and the duration of the eruption and from those using models that assume a constant density. Mass flow rates might be more appropriate because the masses of volatiles in lavas are usually small, but variable and sometimes unknown densities impose severe restrictions on mass estimates.

  16. Notes on the Recent History of Neuroscience in Africa

    PubMed Central

    Russell, Vivienne A.

    2017-01-01

    Neuroscience began with neuroanatomy and neurosurgery in Egypt more than 5000 years ago. Knowledge grew over time and specialized neurosurgery centers were established in north Africa in the eleventh century. However, it was not until the twentieth century that neuroscience research became established in sub-Saharan Africa. In most African countries, clinical research focused on understanding the rationale and improving treatment of epilepsy, infections, nutritional neuropathies, stroke and tumors. Significant advances were made. In the twenty-first century, African knowledge expanded to include all branches of neuroscience, contributing to genetic, biochemical and inflammatory determinants of brain disorders. A major focus of basic neuroscience research has been, and is, investigation of plant extracts, drugs and stress in animal models, providing insight and identifying potential novel therapies. A significant event in the history of African neuroscience was the founding of the Society of Neuroscientists of Africa (SONA) in 1993. The International Brain Research Organization (IBRO) supported SONA conferences, as well as workshops and neuroscience training schools in Africa. Thanks to their investment, as well as that of funding agencies, such as the National Institutes of Health (NIH), International Society for Neurochemistry (ISN), World Federation of Neurosurgical Societies (WFNS), World Federation of Neurology (WFN) and the International League Against Epilepsy (ILAE), neuroscience research is well-established in Africa today. However, in order to continue to develop, African neuroscience needs continued international support and African neuroscientists need to engage in policy and decision-making to persuade governments to fund studies that address the unique regional needs in Africa. PMID:29163069

  17. 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.

  18. Spontaneous Eruption of Premolar Associated with a Dentigerous Cyst.

    PubMed

    de Carvalho, Irla Karlinne Ferreira; Luna, Anibal Henrique Barbosa

    2016-01-01

    Dentigerous cyst (DC) is the second most common odontogenic cyst with greater incidence in young patients. It presents as a unilocular, asymptomatic radiolucency involving the crown of an impacted tooth, commonly noticed in X-rays to investigate absence, wrong tooth position, or delay in the chronology of eruption. Decompression/marsupialization (D/M) is the most implemented treatment, especially when preserving the tooth involved is advised. The aim of this study is to discuss the DC characteristics that contribute to spontaneous eruption of premolars, by reporting the case of a conservative treatment of DC. This eruption depends on factors such as age, angulation of inclusion, rate of root formation, depth of inclusion, and eruption space. This paper reports the case of a 10-year-old patient with a radiolucent lesion diagnosed as DC involving element 35, which erupted as a result of treatment. The patient was observed during 1 year and 6 months.

  19. Spontaneous Eruption of Premolar Associated with a Dentigerous Cyst

    PubMed Central

    Luna, Anibal Henrique Barbosa

    2016-01-01

    Dentigerous cyst (DC) is the second most common odontogenic cyst with greater incidence in young patients. It presents as a unilocular, asymptomatic radiolucency involving the crown of an impacted tooth, commonly noticed in X-rays to investigate absence, wrong tooth position, or delay in the chronology of eruption. Decompression/marsupialization (D/M) is the most implemented treatment, especially when preserving the tooth involved is advised. The aim of this study is to discuss the DC characteristics that contribute to spontaneous eruption of premolars, by reporting the case of a conservative treatment of DC. This eruption depends on factors such as age, angulation of inclusion, rate of root formation, depth of inclusion, and eruption space. This paper reports the case of a 10-year-old patient with a radiolucent lesion diagnosed as DC involving element 35, which erupted as a result of treatment. The patient was observed during 1 year and 6 months. PMID:27313912

  20. Magnetic field restructuring associated with two successive solar eruptions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Rui; Liu, Ying D.; Yang, Zhongwei

    2014-08-20

    We examine two successive flare eruptions (X5.4 and X1.3) on 2012 March 7 in the NOAA active region 11429 and investigate the magnetic field reconfiguration associated with the two eruptions. Using an advanced non-linear force-free field extrapolation method based on the SDO/HMI vector magnetograms, we obtain a stepwise decrease in the magnetic free energy during the eruptions, which is roughly 20%-30% of the energy of the pre-flare phase. We also calculate the magnetic helicity and suggest that the changes of the sign of the helicity injection rate might be associated with the eruptions. Through the investigation of the magnetic fieldmore » evolution, we find that the appearance of the 'implosion' phenomenon has a strong relationship with the occurrence of the first X-class flare. Meanwhile, the magnetic field changes of the successive eruptions with implosion and without implosion were well observed.« less