Science.gov

Sample records for africa began erupting

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  2. Phytoliths Used to Investigate the Effects of the Indonesian Mount Toba Super-Eruption (~75 kyr) in East Africa: A Subdecadal Record from Lake Malawi

    NASA Astrophysics Data System (ADS)

    Yost, C. L.; Cohen, A. S.

    2014-12-01

    The recent discovery of cryptotephra visually and chemically matched to the Youngest Toba Tuff (YTT, 75.0 ± 0.9 kyr) in Lake Malawi drill core sediments has spurred renewed interest in this period of time in East Africa. The YTT is the most recent and largest of the four Mount Toba eruptions, and is the only super-eruption to have taken place during the Quaternary. The timing of the YTT approximately coincides with a hypothesized human genetic bottleneck. Several climate models have proposed an episode of global cooling following the YTT; however, the magnitude and duration of the cooling is much debated, ranging from just a few degrees of cooling to a state of volcanic winter. Cored sediments from Lake Malawi provide an excellent record of local variability in the lake's watershed that may be linked to specific climatic events. To investigate the possible effects of the YTT in East Africa, we continuously sampled Lake Malawi drill core 2A-10H-2 at 2-4 mm (~6 yr) intervals above and below the first occurrence of the YTT. Poaceae phytoliths were grouped into plant functional types (C3, C4, xerophytic, mesophytic, arboreal, etc.), revealing mostly subtle changes in terrestrial vegetation over the ~400 yr time period examined. Abrupt increases in concentration values for phytoliths derived from riverine Podostemaceae plants appear to signal increased discharge from rivers draining the surrounding uplands. Perhaps most significant is the increasing trend in burned phytoliths and decreasing trend in tree phytoliths post-YTT. Although there appears to be a very weak cooling signal synchronous with the YTT, the most abrupt terrestrial vegetation changes appear to be better correlated with the deposition of a slightly older cryptotephra horizon derived from the local Rungwe Volcanic Province. A potential complication with this record is the existence of a turbidite pre-YTT that encompasses the Rungwe horizon.

  3. Africa.

    ERIC Educational Resources Information Center

    Martz, Carlton

    2001-01-01

    This publication explores issues related to Africa. It examines the U.S. response to the Barbary pirate states (Morocco, Algiers, Tunis, Tripoli) in the early 19th century; the current AIDS crisis in Africa; and 14th century Mali and other Islamic lands through the eyes of Ibn Battuta, who traveled throughout the Muslim world. Each article…

  4. Africa.

    ERIC Educational Resources Information Center

    Happel, Sue; Loeb, Joyce

    Although the activities in this unit are designed primarily for students in the intermediate grades, the document's text, illustrations, and bibliographic references are suitable for anyone interested in learning about Africa. Following a brief introduction and map work, the document is arranged into six sections. Section 1 traces Africa's history…

  5. 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. 

  6. The Anthropogenic Era Began Thousands of Years Ago

    NASA Astrophysics Data System (ADS)

    Ruddiman, W. F.

    2003-12-01

    The anthropogenic era is generally thought to have begun about 150 years ago when the industrial revolution began producing CO2 and CH4 at rates sufficient to alter atmospheric compositions. The hypothesis proposed here is that anthropogenic emissions first altered atmospheric gas concentrations (and climate) thousands of years ago. This hypothesis rests on three arguments: (1) Cyclic variations in CO2 and CH4 driven by Earth-orbital changes during the last 400,000 years predict decreases of both gases throughout the Holocene, but CO2 began an anomalous increase near 8000 years ago and CH4 about 5000 years ago. (2) Published explanations attributing these Holocene gas increases to natural forcing can be rejected based on available paleoclimatic evidence. (3) Archeological, cultural, historical, and geologic sources provide viable explanations tied to anthropogenic changes that emerged from early agriculture in Eurasia, including forest clearance after 8000 years ago and lowland irrigation for rice farming by 5000 years ago. Prior to the industrial era, these emissions caused a mean-annual warming effect of ~0.8oC globally and 1.5-2oC at high latitudes. The early-anthropogenic warming counteracted most of a natural cooling that would otherwise have occurred, and it may have prevented a glaciation in northeastern Canada predicted by two kinds of climatic models. CO2 decreases as large as 10 ppm during the last 1000 years cannot be explained by solar-volcanic forcing without violating constraints imposed by reconstructions of northern hemisphere temperature. The CO2 decreases can be explained by bubonic plague pandemics that the caused widespread abandonment of western Eurasian farms documented in historical records. Rapid regrowth of forests on millions of abandoned farms could have sequestered enough carbon to explain the observed CO2 decreases. Plague-driven CO2 decreases were a significant causal factor in the cooler temperatures of the Little Ice Age from 1300 to

  7. How life began on Earth: a status report

    NASA Astrophysics Data System (ADS)

    2004-09-01

    There are two fundamental requirements for life as we know it, liquid water and organic polymers, such as nucleic acids and proteins. Water provides the medium for chemical reactions and the polymers carry out the central biological functions of replication and catalysis. During the accretionary phase of the Earth, high surface temperatures would have made the presence of liquid water and an extensive organic carbon reservoir unlikely. As the Earth's surface cooled, water and simple organic compounds, derived from a variety of sources, would have begun to accumulate. This set the stage for the process of chemical evolution to begin in which one of the central facets was the synthesis of biologically important polymers, some of which had a variety of simple catalytic functions. Increasingly complex macromolecules were produced and eventually molecules with the ability to catalyze their own imperfect replication appeared. Thus began the processes of multiplication, heredity and variation, and this marked the point of both the origin of life and evolution. Once simple self-replicating entities originated, they evolved first into the RNA World and eventually to the DNA/Protein World, which had all the attributes of modern biology. If the basic components water and organic polymers were, or are, present on other bodies in our solar system and beyond, it is reasonable to assume that a similar series of steps that gave rise of life on Earth could occur elsewhere.

  8. Two Amazing Rocket Launches That Began My Career

    NASA Astrophysics Data System (ADS)

    Rothschild, Richard E.

    2013-01-01

    I began my X-ray astronomy career by being given the responsibility for the Goddard rocket program by Frank MacDonald in the early 70's. I am forever grateful to him and Elihu Boldt for the opportunity. The rocket's observing program was three compact binary X-ray sources that could not have been more different: Cyg X-1, Cyg X-3, and Her X-1. A sounding rocket launch is nothing like a satellite launch with its large booster, Cape Canaveral experience, and lots of procedures and no touching of the hardware. First of all, one can walk up to the sounding rocket tower (at least you used to be able to) and go up in it to fix or adjust something with the yet-to-be-fueled rocket, booster, and payload just sitting there. At launch, you can see it up close 100 m) and personal, and it is spectacular. There is an explosion (the Nike booster igniting), a bright flash of light, and it is gone in a second or two. And back in the block house, I watched Her X-1 pulse in real time, after Chuck Glasser calmed me down and explained that the detectors were not arcing but it was Her X-1. The Cyg X-1 observations resulted in the discovery of millisecond temporal structure in the flux from a cosmic source -- 13 1-ms bursts over a total of two minutes of observing in the 2 flights. Cyg X-3 was seen in a high state in the first flight and in a lower harder state in the second, where we detected the iron line for the first time in a Galactic source. The Her X-1 observation clearly showed the high energy roll-over of the spectrum for the first time. The light curves of the first flight found their way into many presentations, including Ricardo Giacconi's Nobel lecture. The Goddard rocket program was an amazing beginning to my career.

  9. Variations in eruption style during the 1931 A.D. eruption of Aniakchak volcano, Alaska

    USGS Publications Warehouse

    Nicholson, Robert S.; Gardner, James E.; Neal, Christina A.

    2011-01-01

    The 1931 A.D. eruption of Aniakchak volcano, Alaska, progressed from subplinian to effusive eruptive style and from trachydacite to basaltic andesite composition from multiple vent locations. Eyewitness accounts and new studies of deposit stratigraphy provide a combined narrative of eruptive events. Additional field, compositional, grain size, componentry, density, and grain morphology data document the influences on changing eruptive style as the eruption progressed. The eruption began on 1 May 1931 A.D. when a large subplinian eruption column produced vesicular juvenile-rich tephra. Subsequent activity was more intermittent, as magma interacted with groundwater and phreatomagmatic ash and lithic-rich tephra was dispersed up to 600 km downwind. Final erupted products were more mafic in composition and the eruption became more strombolian in style. Stratigraphic evidence suggests that two trachydacitic lava flows were erupted from separate but adjacent vents before the phreatomagmatic phase concluded and that basaltic andesite lava from a third vent began to effuse near the end of explosive activity. The estimated total bulk volume of the eruption is 0.9 km3, which corresponds to approximately 0.3 km3 of magma. Eruption style changes are interpreted as follows: (1) a decrease in magma supply rate caused the change from subplinian to phreatomagmatic eruption; (2) a subsequent change in magma composition caused the transition from phreatomagmatic to strombolian eruption style. Additionally, the explosion and effusion of a similar magma composition from three separate vents indicates how the pre-existing caldera structure controlled the pathway of shallow magma ascent, thus influencing eruption style.

  10. Variations in eruption style during the 1931A.D. eruption of Aniakchak volcano, Alaska

    USGS Publications Warehouse

    Nicholson, R.S.; Gardner, J.E.; Neal, C.A.

    2011-01-01

    The 1931A.D. eruption of Aniakchak volcano, Alaska, progressed from subplinian to effusive eruptive style and from trachydacite to basaltic andesite composition from multiple vent locations. Eyewitness accounts and new studies of deposit stratigraphy provide a combined narrative of eruptive events. Additional field, compositional, grain size, componentry, density, and grain morphology data document the influences on changing eruptive style as the eruption progressed. The eruption began on 1 May 1931A.D. when a large subplinian eruption column produced vesicular juvenile-rich tephra. Subsequent activity was more intermittent, as magma interacted with groundwater and phreatomagmatic ash and lithic-rich tephra was dispersed up to 600km downwind. Final erupted products were more mafic in composition and the eruption became more strombolian in style. Stratigraphic evidence suggests that two trachydacitic lava flows were erupted from separate but adjacent vents before the phreatomagmatic phase concluded and that basaltic andesite lava from a third vent began to effuse near the end of explosive activity. The estimated total bulk volume of the eruption is 0.9km3, which corresponds to approximately 0.3km3 of magma. Eruption style changes are interpreted as follows: (1) a decrease in magma supply rate caused the change from subplinian to phreatomagmatic eruption; (2) a subsequent change in magma composition caused the transition from phreatomagmatic to strombolian eruption style. Additionally, the explosion and effusion of a similar magma composition from three separate vents indicates how the pre-existing caldera structure controlled the pathway of shallow magma ascent, thus influencing eruption style. ?? 2011 Elsevier B.V..

  11. Creeping eruption

    MedlinePlus

    ... JavaScript. Creeping eruption is a human infection with dog or cat hookworm larvae (immature worms). Causes Hookworm eggs are found in the stool of infected dogs and cats. When the eggs hatch, the larvae ...

  12. 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

  13. Polymorphic light eruption sine eruption.

    PubMed

    Dover, J S; Hawk, J L

    1988-01-01

    We describe seven patients, four female and three male, who developed intense pruritus on sun-exposed skin without visible change. The clinical features resembled those of polymorphic light eruption (PLE) without rash. Four patients also occasionally developed typical PLE upon sun exposure, but sun-induced pruritus alone occurred most frequently. No patient was taking any drug therapy. One patient developed similar pruritus following solar simulated irradiation, and one following PUVA therapy. All other laboratory investigations were negative. Treatment with low dose UVB phototherapy or PUVA therapy was effective. The condition, which we have called polymorphic light eruption sine eruptione (PLESE), appears to be a variant of PLE not previously reported.

  14. 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.

  15. Eruptive xanthomas.

    PubMed

    Zaremba, Joanna; Zaczkiewicz, Andrzej; Placek, Waldemar

    2013-12-01

    Xanthomas are localized lipid deposits in the skin, tendons and subcutaneous tissue associated with lipid abnormality. The hyperlipidemia responsible for this disorder can be caused by a primary genetic defect, a secondary disorder, or both. That kind of skin exanthema may be the first signal of cardiovascular risk. We present a 24-year-old woman with a skin eruption that had appeared a few months earlier.

  16. Eruptive xanthomas

    PubMed Central

    Zaczkiewicz, Andrzej; Placek, Waldemar

    2013-01-01

    Xanthomas are localized lipid deposits in the skin, tendons and subcutaneous tissue associated with lipid abnormality. The hyperlipidemia responsible for this disorder can be caused by a primary genetic defect, a secondary disorder, or both. That kind of skin exanthema may be the first signal of cardiovascular risk. We present a 24-year-old woman with a skin eruption that had appeared a few months earlier. PMID:24494004

  17. 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

  18. A Case Study of a Career in Education that Began with "Teach for America"

    ERIC Educational Resources Information Center

    Tellez, Kip

    2011-01-01

    In this article I share the results of a seven-year case study of an educator who began his career without formal preservice teacher education, as a participant in Teach for America. Steven (a pseudonym) began teaching mathematics in an urban middle school, later teaching social studies to English language learners, and is currently a principal of…

  19. Jupiter Eruptions

    NASA Technical Reports Server (NTRS)

    2008-01-01

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

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

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

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    The May, 2008 - present eruption at Chaitén caldera is the only example of a geophysically monitored rhyolite eruption. Geologic and seismic monitoring was conducted by the Chilean Servicio Nacional de Geología y Minería (SERNAGEOMIN) with assistance from the Volcano Disaster Assistance Program (VDAP, a joint program of USGS and OFDA). In addition, global remote sensing assets were focused on the eruption and provide extensive data on the eruptive plume and ash cloud. An initial analysis of seismic and observational monitoring and remote sensing data lead us to suggest that the Chaitén eruption was tectonically controlled, as described below. The Chaitén eruption began abruptly with Plinian ash columns (May 2-8), and then transitioned into lava dome effusion accompanied by continuous low-level ash plumes. Heights and durations of the Plinian phase of the eruption initially suggested magmatic volumes of up to as much as 1 km3, ranking this as a large VEI 4 or possibly a small VEI 5 eruption. However, reports of relatively modest thicknesses of downwind tephra indicate a smaller explosivity, probably in the moderate VEI 4 range. Extrusion of the lava dome continues at a high rate as of this time (mid-September, 2008). We estimate a lava volume of >0.3 km3 and eruption rates that have frequently exceeded 20 m3s-1, anomalously high rates for a sustained lava dome eruption. Little detailed on-site study of the proximal deposits of the eruption has been possible because of continued hazards from the eruption and austral winter weather conditions. However, several inferences about the nature of the eruption are evident. The apparent lack of historic eruptions, absence of a hydrothermal system, rapid onset of the eruption, crystal-poor rhyolite composition, lack of decompression reaction rims on amphibole crystals, and relatively high magmatic temperatures (about 860°C, as reported elsewhere in this session) all argue for rapid ascent of magma from depth. The

  1. 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

  2. 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

  3. Some aspect of seismicity prior to the 27 November 2006 eruption of Nyamuragira volcano and its implication for volcano monitoring and risk mitigation in the Virunga area, Western Rift Valley of Africa

    NASA Astrophysics Data System (ADS)

    Mavonga, Tuluka; Kavotha, Sadaka K.; Lukaya, Nyombo; Etoy, Osodundu; Mifundu, Wafula; Bizimungu, Rusangiza K.; Durieux, Jacques

    2010-12-01

    The temporal variation in the seismicity in the Nyamuragira area was investigated for the period 1 July 2004-27 November 2006, prior to the 27 November 2006 eruptions of Nyamuragira. It is found that this eruption was preceded by 11 months by progressive increase in number of long-period earthquakes. This pattern of seismicity, integrated with other geophysical, geological and geochemistry data, is useful for volcano monitoring and risk mitigation.

  4. Filament Eruption Onset

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2011-01-01

    We have been investigating filament eruptions in recent years. Use filament eruptions as markers of the coronal field evolution. Data from SoHO, Yohkoh, TRACE, Hinode, and other sources. We and others have observed: (1)Filaments often show slow rise, followed by fast rise, (2) Brightenings, preflares, microflares during slow rise (3) Magnetic evolution in hours prior to eruption onset. We investigated What do Hinode and SDO show for filament eruptions?

  5. An erupted compound odontoma.

    PubMed

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

    2014-04-12

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

  6. 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

  7. 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

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

    SciTech Connect

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

    1993-04-01

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

  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. 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.

  11. 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

  12. 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.

  13. MtDNA analysis of global populations support that major population expansions began before Neolithic Time

    NASA Astrophysics Data System (ADS)

    Zheng, Hong-Xiang; Yan, Shi; Qin, Zhen-Dong; Jin, Li

    2012-10-01

    Agriculture resulted in extensive population growths and human activities. However, whether major human expansions started after Neolithic Time still remained controversial. With the benefit of 1000 Genome Project, we were able to analyze a total of 910 samples from 11 populations in Africa, Europe and Americas. From these random samples, we identified the expansion lineages and reconstructed the historical demographic variations. In all the three continents, we found that most major lineage expansions (11 out of 15 star lineages in Africa, all autochthonous lineages in Europe and America) coalesced before the first appearance of agriculture. Furthermore, major population expansions were estimated after Last Glacial Maximum but before Neolithic Time, also corresponding to the result of major lineage expansions. Considering results in current and previous study, global mtDNA evidence showed that rising temperature after Last Glacial Maximum offered amiable environments and might be the most important factor for prehistorical human expansions.

  14. 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

  15. Linear drug eruption.

    PubMed

    Alfonso, R; Belinchon, I

    2001-01-01

    Linear eruptions are sometimes associated with systemic diseases and they may also be induced by various drugs. Paradoxically, such acquired inflammatory skin diseases tend to follow the system of Blaschko's lines. We describe a case of unilateral linear drug eruption caused by ibuprofen, which later became bilateral and generalized.

  16. Generalized Eruptive Syringoma

    PubMed Central

    Avhad, Ganesh; Ghuge, Priyanka; Jerajani, HR

    2015-01-01

    Eruptive syringoma is a very rare variant of syringoma. It is a benign adnexal tumor of the intraepidermal portion of eccrine sweat ducts. Here we report a 32-year-old female presented with classical asymptomatic eruptive syringomas involving her face and extremities. PMID:25814740

  17. 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.

  18. 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

  19. A FILAMENT ERUPTION ON 2010 OCTOBER 21 FROM THREE VIEWPOINTS

    SciTech Connect

    Filippov, Boris

    2013-08-10

    A filament eruption on 2010 October 21 observed from three different viewpoints by the Solar Terrestrial Relations Observatory and the Solar Dynamic Observatory is analyzed by also invoking data from the Solar and Heliospheric Observatory and the Kanzelhoehe Solar Observatory. The position of the filament just before the eruption at the central meridian not far from the center of the solar disk was favorable for photospheric magnetic field measurements in the area below the filament. Because of this, we were able to calculate with high precision the distribution of the coronal potential magnetic field near the filament. We found that the filament began to erupt when it approached the height in the corona where the magnetic field decay index was greater than 1. We also determined that during the initial stage of the eruption the filament moved along the magnetic neutral surface.

  20. Mt. Etna Eruption

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

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

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

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

    The

  1. 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.

  2. Observations, stratigraphy and eruptive processes of the 1990 eruption of Kelut volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Bourdier, Jean-Louis; Pratomo, Indyo; Thouret, Jean-Claude; Boudon, Georges; Vincent, Pierre M.

    1997-12-01

    The February 10, 1990 eruption of Kelut volcano (eastern Java) reportedly began with seven discrete, short-lived explosions between 11.41 and 12.35 local times. Deposits of this initial, phreatomagmatic stage include a basal ash-fall layer (unit A1), widespread pumice surge deposits (unit S) and related pisolitic ash layer (unit A2). The main, plinian phase of the eruption lasted about 4 hours from 12.35 and produced pumice-flow deposits (unit PF) overlain by a pumice fallout layer distributed mainly to the southwest (unit P), and intra-plinian scoria-flow deposits (unit SF). Uppermost scoria-rich ash fall layers (unit A3) likely relate to late, discrete eruptive pulses. A few small explosions resumed on February 11 and 12 leaving no recognizable deposit. An embryonic lava dome had formed in the crater bottom by April, then was submerged by the new crater lake. Destruction of the summit area resulted from emplacement of the pre-plinian pumice surge up to 4-5 km on the south and west flanks, and of the early plinian pumice flows up to 1-2 km radially from the crater, before these were channelized in the main valleys to further travel 3 km. Most of the 32 human deaths resulted from roof collapse under the load of fallout tephra beyond the devastated area, which had been evacuated before the eruption began. The eruption produced 0.13 km 3 of tephra, of which 0.12 km 3 represent the products of the plinian phase. The average eruptive rate of the plinian phase is estimated to have been ˜7.5×10 6 kg/s magma DRE. The pumice flows are interpreted to have been formed due to unsteadiness and low velocity of the eruptive column at the beginning of the plinian phase. The intra-plinian scoria flows incorporate either more degassed or colder juvenile magma; they were presumably erupted at the edge of the column, due to fluctuations in the mass flux and in pressure in the conduit.

  3. Large numbers of vertebrates began rapid population decline in the late 19th century

    PubMed Central

    Li, Haipeng; Xiang-Yu, Jinggong; Dai, Guangyi; Gu, Zhili; Ming, Chen; Yang, Zongfeng; Ryder, Oliver A.; Li, Wen-Hsiung; Fu, Yun-Xin; Zhang, Ya-Ping

    2016-01-01

    Accelerated losses of biodiversity are a hallmark of the current era. Large declines of population size have been widely observed and currently 22,176 species are threatened by extinction. The time at which a threatened species began rapid population decline (RPD) and the rate of RPD provide important clues about the driving forces of population decline and anticipated extinction time. However, these parameters remain unknown for the vast majority of threatened species. Here we analyzed the genetic diversity data of nuclear and mitochondrial loci of 2,764 vertebrate species and found that the mean genetic diversity is lower in threatened species than in related nonthreatened species. Our coalescence-based modeling suggests that in many threatened species the RPD began ∼123 y ago (a 95% confidence interval of 20–260 y). This estimated date coincides with widespread industrialization and a profound change in global living ecosystems over the past two centuries. On average the population size declined by ∼25% every 10 y in a threatened species, and the population size was reduced to ∼5% of its ancestral size. Moreover, the ancestral size of threatened species was, on average, ∼22% smaller than that of nonthreatened species. Because the time period of RPD is short, the cumulative effect of RPD on genetic diversity is still not strong, so that the smaller ancestral size of threatened species may be the major cause of their reduced genetic diversity; RPD explains 24.1–37.5% of the difference in genetic diversity between threatened and nonthreatened species. PMID:27872315

  4. 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.

  5. Quantifying the eruption cycle at Axial Seamount using submarine geodesy

    NASA Astrophysics Data System (ADS)

    Nooner, S. L.; Chadwick, B.

    2011-12-01

    Bottom pressure instruments within the caldera of Axial Seamount recorded subsidence during eruptions in 1998 and again in April 2011, for a total repeat time of 13 years. We present here a summary of the vertical deformation history at Axial and describe what that tells us about changes in magma supply over an entire eruption cycle. Over the last 13 years we have used a combination of continuously recording bottom pressure recorder (BPR) instruments and campaign style mobile pressure recorder (MPR) surveys to document changes in the elevation of the caldera floor. These observations of caldera deformation directly reflect changes in the magmatic system throughout the entire volcanic eruption cycle. Rapid inflation of the volcano (>50 cm/yr) started immediately after the 1998 eruption and began slowing exponentially within a few months, ultimately transitioning to a constant linear inflation rate of 15 cm/yr that continued until the 2011 eruption. We interpret these two different inflation regimes as the surface manifestation of two entirely different recharge mechanisms within the magma chamber: 1) Short-duration poroelastic flow and viscoelastic relaxation immediately following eruption, and 2) Long-term linear recharge from the mantle. The second mechanism suggests that long-term flow rates from the mantle are controlled by permeability rather than pressure at Axial. Finally, we present evidence that the pattern of deformation at Axial can be used as a method of forecasting future eruptions here.

  6. Drivers of explosivity and elevated hazard in basaltic fissure eruptions: The 1913 eruption of Ambrym Volcano, Vanuatu (SW-Pacific)

    NASA Astrophysics Data System (ADS)

    Németh, Károly; Cronin, Shane J.

    2011-04-01

    Fissure-eruptions along linear structures can extend for several tens of kilometres with distinct separate manifestations of volcanism along their length. They typically involve low-viscosity mafic magmas forming long lava flows and cinder cones. Eruptions in 1894 and 1913 on Ambrym volcano, Vanuatu, showed how these mildly explosive eruptions can rapidly transform into violent explosive events, producing significant hazard and widespread volcanic ash clouds. During the 1913 episode, a fissure began in the central caldera and basaltic magmas broke out in a series of locations down the island's western flank. In all sites over 100 m in elevation, fissure outbreaks produced vigorous lava fountains and highly fluid lava flows that travelled rapidly to the shoreline. When the outbreaks propagated along the island's axis into coastal plain areas, a climactic series of explosive eruptions occurred, producing a 1.2 km long by 600 m wide maar and tephra ring. A further small tuff ring was formed later, creating a temporary island 400 m offshore. The onshore tephra ring destroyed a hospital and associated buildings. Its last evacuating occupants were close witnesses to the eruption processes. Deposits exposed in the lower portion of the tephra ring show that this part of the eruption began with a mild phreatomagmatic explosive eruption from a narrow vent, followed by a magmatic scoria-producing phase. Subsequently a complex sequence of highly explosive phreatomagmatic eruptions occurred, producing pyroclastic surges, along with repeated distinctive breccia-horizons, rich in coral and lava country rock. These features tally with eye-witness accounts to indicate that the main eruption phase was produced by a periodically shifting locus of phreatomagmatic fragmentation and eruption along a single E-W fissure. The glassy and vesicle-poor pyroclasts produced during this eruption phase were dominantly fragmented in a brittle manner by magma water interaction. Low volatile content

  7. 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.

  8. Estimates of eruption velocity and plume height from infrasonic recordings of the 2006 eruption of Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Caplan-Auerbach, Jacqueline; Bellesiles, Anna; Fernandes, Jennifer K.

    2010-01-01

    The 2006 eruption of Augustine Volcano, Alaska, began with an explosive phase comprising 13 discrete Vulcanian blasts. These events generated ash plumes reaching heights of 3-14 km. The eruption was recorded by a dense geophysical network including a pressure sensor located 3.2 km from the vent. Infrasonic signals recorded in association with the eruptions have maximum pressures ranging from 13-111 Pa. Eruption durations are estimated to range from 55-350 s. Neither of these parameters, however, correlates with eruption plume height. The pressure record, however, can be used to estimate the velocity and flux of material erupting from the vent, assuming that the sound is generated as a dipole source. Eruptive flux, in turn, is used to estimate plume height, assuming that the plume rises as a buoyant thermal. Plume heights estimated in this way correlate well with observations. Events that exhibit strongly impulsive waveforms are underestimated by the model, suggesting that flow may have been supersonic.

  9. Compositional variation through the Surtsey eruption, 1963-1967

    NASA Astrophysics Data System (ADS)

    White, J. D. L.; Jakobsson, S. P.; Schipper, C. I.

    2014-12-01

    The volcanic island of Surtsey is the best-known product of a 3.5-year-long eruption that began in November 1963. During the course of the eruption four volcanic edifices grew from the seafloor along a discontinuous fissure extending 4.5 km, with three of them forming islands. Two of the islands washed quickly away - Syrtlingur lasted 5 months, and Jolnir 11 months. Surtla grew to within meters of the sea surface before its eruption ceased without forming an island. These separate eruptive centers along the Surtsey fissure produced edifices totalling ~0.15 km3 (Syrtlingur and Jolnir ~ 0.07 km3 each; Surtla ~0.01 km3), nearly half the volume of Surtsey below sea level (~0.3 km3). Although Surtsey's explosive activity ceased after 6 months, it was more than 3 years into the eruption when the last pyroclastic activity at Jolnir ceased, and during most of the time that Syrtlingur and Jolnir were erupting, there was no subaerial eruption at Surtsey. Here we present previously unpublished historic data on chemical diversity through the Surtsey eruption, bolstered with new analyses, and address specifically the other centers that were active during the eruption. Whole-rock compositions became progressively more magnesian as the eruption progressed (rising from 7 to 12% MgO), with a subtle concomitant reduction in potassium (0.7% to 0.4%). Glass compositions show considerable variation early in the eruption at Surtsey (~4.5-6.2 % MgO; 46.5-48.2% SiO2), but changed little through the remainder of the eruption (~7% MgO; 48% SiO2) at all sites. Glasses from Jolnir and Syrtlingur have overlapping compositions that form a separate cluster from those of Surtsey (more calcic, less potassic). Surtla, represented by only one sample and erupted at the greatest distance from Surtsey, has slightly more-evolved glass (lower MgO, higher FeOt), but this may reflect post-fragmentation crystal growth. Using this information we present a new assessment of magma-supply dynamics for this

  10. Modelling VLP sources for the 25 September 2007 Ruapehu eruption

    NASA Astrophysics Data System (ADS)

    Jolly, A. D.; Jousset, P.; Sherburn, S.

    2008-12-01

    Mt. Ruapehu erupted on 25 September 2007 at 20:26 PM NZDT (8:26 UT) generating a moderate steam column to about 15,000 feet, a directed ballistic and surge deposit of coarse blocks and ash to the north of the Crater Lake, and initiated lahars in the Whangaehu catchment and Whakapapa ski field. The eruption was recorded on three broadband seismometers and two acoustic pressure sensors which indicated broadly coherent waveform characteristics across the network. The eruption had duration of less than 1 minute as indicated by strong seismic and acoustic pulses. The acoustic wave coincided with observed very long period (VLP) seismic signal (7-25 s period with 13 s peak). The acoustic pulse had positive pressure (indicating an explosion) and travelled at a velocity of ~320 m/s. The associated VLP ground displacement (elastic velocity ~2500 m/s) changed from negative (compression) to positive (dilatation) at the onset of the eruption. The syn-eruptive VLP was composed of surface waves having strong radial and transverse components which varied dependent on station azimuth and distance. The immediate aftermath of the eruption produced about 3 minutes of continued high amplitude spasmodic tremor signals that probably resulted from post-explosion phase associated vent backfill/stabilisation. The eruption was preceded by minor volcano-tectonic earthquakes and tremor pulses which began 10 minutes before the main eruption. Two smaller VLP pulses were associated with these tremor pulses at 20:16 and 20:25. These pre-eruptive VLP pulses had particle motions indicating body waves from a subsurface source region less than 4 km below the surface. We are modelling pre-eruption and eruption VLP pulses using a three-dimensional finite-difference scheme which incorporates topography. Data (from three broadband stations) are insufficient to determine uniquely constrained source processes. However the data are sufficient to test specific pre and syn-eruption source models. We aim to

  11. Snake Filament Eruption

    NASA Video Gallery

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

  12. Triple Solar Eruption

    NASA Video Gallery

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

  13. The Chaitén 2008 eruption: explosive eruption characteristics and tephra dispersal

    NASA Astrophysics Data System (ADS)

    Watt, S. F. L.; Pyle, D. M.

    2012-04-01

    Chaitén volcano, situated in the southern Chilean Andes at 42.8 °S, began erupting explosively and without warning on 2nd May 2008. The early and most intense stages of the eruption lasted approximately one week, and represented the largest explosive eruption globally since that of Hudson, Chile, in 1991. The eruption was also the first explosive eruption of rhyolitic magma for almost a century. Widespread tephra deposition caused significant regional-scale disruption to agriculture, and aviation across southern Chile and Argentina was periodically affected for one month. Severe local impacts in Chile led to the evacuation of more than 5000 people. The proximal tephra fall deposit contains multiple layers, corresponding to individual eruption phases. Early clearing of the conduit produced a dense rhyolitic lapilli deposit with very little juvenile material. This was followed by pulsatory explosions of extremely homogeneous crystal-poor rhyolite. The overall volume of the tephra fall deposit was ~0.2 km3 (dense-rock equivalent). Eruption column heights reached ~19 km height during the most energetic phases, but these were of notably short duration given their intensity. After 8th May 2008 the Chaitén eruption entered a dome-forming stage, which is ongoing. The series of explosive phases during the first week of the Chaitén eruption interacted with a strong and variable wind field. This produced a complex, lobate fall deposit that reached the Atlantic coast of Argentina and covered ~2 × 105 km2. Measurable ash fallout occurred at a distance of 1000 km downwind. Ground measurements of the distal ash deposit correspond well with satellite observations of plume dispersal and ash deposition, and reflect the differing transport directions of ash-rich clouds from separate explosive phases. The overlap of multiple deposits in the medial fallout region is confirmed by the multiple modes in deposit grain-size distributions. Grain-size measurements also provide evidence

  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. An erupted complex odontoma.

    PubMed

    Tozoglu, Sinan; Yildirim, Umran; Buyukkurt, M Cemil

    2010-01-01

    Odontomas are benign tumors of odontogenic origin. The cause of the odontoma is unknown, but it is believed to be hereditary or due to a disturbance in tooth development triggered by trauma or infection. Odontomas may be either compound or complex. Although these tumors are seen frequently, erupted odontomas are rare. The purpose of this study is to present a rare case of complex odontoma that erupted into the oral cavity.

  16. Dating the period when intensive anthropogenic activity began to influence the Sanjiang Plain, Northeast China

    NASA Astrophysics Data System (ADS)

    Cong, Jinxin; Gao, Chuanyu; Zhang, Yan; Zhang, Shaoqing; He, Jiabao; Wang, Guoping

    2016-02-01

    Dating the start of intensive anthropogenic influence on ecosystems is important for identifying the conditions necessary for ecosystem recovery. However, few studies have focused on determining when anthropogenic influences on wetland began through sedimentary archives. To fill this critical gap in our knowledge, combustion sources and emission intensities, reconstructed via black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) were analyzed in two wetlands in the Sanjiang Plain in Northeast China. 14C provided age control for the sedimentary records. By combining previous sedimentary and archaeological studies, we attempt to date the beginning of intensive anthropogenic influences on the Sanjiang Plain. Our results showed that BC deposition fluxes increased from 0.02 to 0.7 g C/m2.yr during the last 10,000 years. An upward trend was apparent during the last 500 years. Before 1200 cal yr BP, human activities were minor, such that the wetland ecosystem in the Sanjiang Plain before this period may represent the reference conditions that for the recovery of these wetlands. As the human population increased after 1200 cal yr BP, combustion sources changed and residential areas became a major source of BC and PAHs. In this way, the wetland ecosystem gradually became more heavily influenced by human activities.

  17. Dating the period when intensive anthropogenic activity began to influence the Sanjiang Plain, Northeast China.

    PubMed

    Cong, Jinxin; Gao, Chuanyu; Zhang, Yan; Zhang, Shaoqing; He, Jiabao; Wang, Guoping

    2016-02-24

    Dating the start of intensive anthropogenic influence on ecosystems is important for identifying the conditions necessary for ecosystem recovery. However, few studies have focused on determining when anthropogenic influences on wetland began through sedimentary archives. To fill this critical gap in our knowledge, combustion sources and emission intensities, reconstructed via black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) were analyzed in two wetlands in the Sanjiang Plain in Northeast China. (14)C provided age control for the sedimentary records. By combining previous sedimentary and archaeological studies, we attempt to date the beginning of intensive anthropogenic influences on the Sanjiang Plain. Our results showed that BC deposition fluxes increased from 0.02 to 0.7 g C/m(2).yr during the last 10,000 years. An upward trend was apparent during the last 500 years. Before 1200 cal yr BP, human activities were minor, such that the wetland ecosystem in the Sanjiang Plain before this period may represent the reference conditions that for the recovery of these wetlands. As the human population increased after 1200 cal yr BP, combustion sources changed and residential areas became a major source of BC and PAHs. In this way, the wetland ecosystem gradually became more heavily influenced by human activities.

  18. Dating the period when intensive anthropogenic activity began to influence the Sanjiang Plain, Northeast China

    PubMed Central

    Cong, Jinxin; Gao, Chuanyu; Zhang, Yan; Zhang, Shaoqing; He, Jiabao; Wang, Guoping

    2016-01-01

    Dating the start of intensive anthropogenic influence on ecosystems is important for identifying the conditions necessary for ecosystem recovery. However, few studies have focused on determining when anthropogenic influences on wetland began through sedimentary archives. To fill this critical gap in our knowledge, combustion sources and emission intensities, reconstructed via black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) were analyzed in two wetlands in the Sanjiang Plain in Northeast China. 14C provided age control for the sedimentary records. By combining previous sedimentary and archaeological studies, we attempt to date the beginning of intensive anthropogenic influences on the Sanjiang Plain. Our results showed that BC deposition fluxes increased from 0.02 to 0.7 g C/m2.yr during the last 10,000 years. An upward trend was apparent during the last 500 years. Before 1200 cal yr BP, human activities were minor, such that the wetland ecosystem in the Sanjiang Plain before this period may represent the reference conditions that for the recovery of these wetlands. As the human population increased after 1200 cal yr BP, combustion sources changed and residential areas became a major source of BC and PAHs. In this way, the wetland ecosystem gradually became more heavily influenced by human activities. PMID:26907560

  19. pp iii How life began on Earth: a status report [rapid communication

    NASA Astrophysics Data System (ADS)

    Bada, Jeffrey L.

    2004-09-01

    There are two fundamental requirements for life as we know it, liquid water and organic polymers, such as nucleic acids and proteins. Water provides the medium for chemical reactions and the polymers carry out the central biological functions of replication and catalysis. During the accretionary phase of the Earth, high surface temperatures would have made the presence of liquid water and an extensive organic carbon reservoir unlikely. As the Earth's surface cooled, water and simple organic compounds, derived from a variety of sources, would have begun to accumulate. This set the stage for the process of chemical evolution to begin in which one of the central facets was the synthesis of biologically important polymers, some of which had a variety of simple catalytic functions. Increasingly complex macromolecules were produced and eventually molecules with the ability to catalyze their own imperfect replication appeared. Thus began the processes of multiplication, heredity and variation, and this marked the point of both the origin of life and evolution. Once simple self-replicating entities originated, they evolved first into the RNA World and eventually to the DNA/Protein World, which had all the attributes of modern biology. If the basic components water and organic polymers were, or are, present on other bodies in our solar system and beyond, it is reasonable to assume that a similar series of steps that gave rise of life on Earth could occur elsewhere.

  20. Petrological Characteristic of Recent Eruption Events at Galeras Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Nakada, S.; Noguchi, S.; Cortes, G. P.; Calvache, M. L.

    2007-12-01

    On-going volcanic activity at Galeras began in 1988, and major explosive eruption events occurred in 1993. Long- period seismic events had occurred before these events. In late 2004, explosive eruptive events resumed and intermittently continued by the present. Long-period events similar to those before the 1993 explosive eruptive events have been observed since early 2006. Evaluating potential of more explosive future eruptions becomes very important to minimize volcanic disasters in cities and towns around this volcano, including the city of Pasto. Investigation of temporal changes in petrological characteristics of eruption products makes us possible to understand the magma system undergone at Galeras. Whether has it changed (or developed) from the 1993 explosive events or not? Ballistics and scoria of vulcanian explosions during 2004-2006 and of the 1991 eruption were investigated in this paper. Rocks are two pyroxene andesite with various crystallinity in groundmass. Small amount of hornblende and olivine microphenocrsyts are involved. The whole rock chemistry hardly changed with time. Lines of petrological evidence suggest that magma mixing occurred throughout the eruption products during 1991-2006; 1) bimodal populations in core compositions of plagioclase phenocrysts, 2) plagioclase microlites with the composition between the two polulations, 3) plagioclase phenocrysts rims more enriched in Fe, and 4) reverse zoning of pyroxene phenocrysts that rather show single chemical population. Melt inclusions in pyroxene phenocrysts are slightly less evolved than the groundmass glass, suggesting that most pyroxenes were derived from felsic magma. These suggest mixing of low-temperature hydrous felsic magma with high-temperature anhydrous (pyroxene-free) mafic magma. Similarity in the petrographical characteristics and temperatures with the pyroxene geothermometry among all the samples shows that nearly constant mixing processes has been operated throughout the recent

  1. 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 SO2 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.

  2. 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

  3. 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

  4. Eruption column physics

    SciTech Connect

    Valentine, G.A.

    1997-03-01

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

  5. Ritodrine-induced pustular eruptions distinctly resembling impetigo herpetiformis.

    PubMed

    Kuwabara, Yoshimitsu; Sato, Atsuki; Abe, Hiroko; Abe, Sumino; Kawai, Naoki; Takeshita, Toshiyuki

    2011-01-01

    A 27-year-old nulligravida woman without a history of dermatosis was hospitalized for threatened preterm labor at 29 weeks' gestation; therefore, continuous infusion of ritodrine hydrochloride was started. At 31 weeks' gestation, erythematous plaques appeared and spread over the body surface; therefore, a topical steroid preparation was applied. At 32 weeks' gestation, the eruptions developed into irregular annular areas of erythema with multiple pustules accompanied by severe itching, and oral prednisolone treatment was started. Bacterial cultures of the pustules were negative, and a crural cutaneous biopsy revealed Kogoj's spongiform pustules. Based on the clinicopathological findings, the most likely diagnosis was impetigo herpetiformis, which causes cutaneous symptoms closely resembling pustular psoriasis in pregnant females without a history of psoriasis. To rule out ritodrine-induced pustular eruptions, the ritodrine infusion was stopped and treatment with an MgSO(4) preparation was started at 33 weeks' 3 days' gestation; however, the uterine contractions could not be suppressed. Because of the patient's highly edematous, severely painful feet, a cesarean section was performed the same day. Within several days of delivery, the eruptions began to resolve, and no recurrence was observed after treatment with oral prednisolone was stopped 31 days after delivery. On the basis of a positive patch test for ritodrine, we diagnosed pustular drug eruptions caused by ritodrine hydrochloride. Although ritodrine-induced pathognomonic cutaneous eruptions are rare, we would like to emphasize that ritodrine can cause drug-induced pustular eruptions distinctly resembling life-threatening impetigo herpetiformis.

  6. 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

  7. 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.

  8. Seasonality of Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

    An analysis of volcanic activity in the last three hundred years reveals that the frequency of onset of volcanic eruptions varies systematically with the time of year. We analysed the Smithsonian catalogue of more than 3200 subaerial eruptions recorded during the last 300 years. We also investigated continuous records, which are not part of the general catalogue, of individual explosions at Sakurajima volcano (Japan, 150 events per year since 1955) and Semeru (Indonesia, 100,000 events during the period 1997-2000). A higher proportion (as much as 18 percent of the average monthly rate) of eruptions occur worldwide between December and March. This observation is statistically significant at above the 99 percent level. This pattern is independent of the time interval considered, and emerges whether individual eruptions are counted with equal weight or with weights proportional to event explosivity. Elevated rates of eruption onset in boreal winter months are observed in northern and southern hemispheres alike, as well as in most volcanically-active regions including, most prominently, the 'Ring of Fire' surrounding the Pacific basin. Key contributors to this regional pattern include volcanoes in Central and South America, the volcanic provinces of the northwest Pacific rim, Indonesia and the southwest Pacific basin. On the smallest spatial scales, some individual volcanoes for which detailed histories exist exhibit peak levels in eruption activity during November-January. Seasonality is attributed to one or more mechanisms associated with the annual hydrological cycle, and may correspond to the smallest time-scale over which fluctuations in stress due to the redistribution of water-masses are felt by the Earth's crust. Our findings have important ramifications for volcanic risk assessment, and offer new insight into possible changes in volcanic activity during periods of long-term changes in global sea level.

  9. Seasonality of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Mason, B.; Pyle, D.; Dade, B.; Jupp, T.

    2003-04-01

    An analysis of volcanic activity in the last three hundred years reveals that the frequency of onset of volcanic eruptions varies systematically with the time of year. We analysed the Smithsonian catalogue of more than 3200 subaerial eruptions recorded during the last 300 years. We also investigated continuous records, which are not part of the general catalogue, of individual explosions at Sakurajima volcano (Japan, 150 events per year since 1955) and Semeru (Indonesia, 100,000 events during the period 1997-2000). A higher proportion (as much as 18 percent of the average monthly rate) of eruptions occur worldwide between December and March. This observation is statistically significant at above the 99 percent level. This pattern is independent of the time interval considered, and emerges whether individual eruptions are counted with equal weight or with weights proportional to event explosivity. Elevated rates of eruption onset in boreal winter months are observed in northern and southern hemispheres alike, as well as in most volcanically-active regions including, most prominently, the 'Ring of Fire' surrounding the Pacific basin. Key contributors to this regional pattern include volcanoes in Central and South America, the volcanic provinces of the northwest Pacific rim, Indonesia and the southwest Pacific basin. On the smallest spatial scales, some individual volcanoes for which detailed histories exist exhibit peak levels in eruption activity during November-January. Seasonality is attributed to one or more mechanisms associated with the annual hydrological cycle, and may correspond to the smallest time-scale over which fluctuations in stress due to the redistribution of water-masses are felt by the Earth's crust. Our findings have important ramifications for volcanic risk assessment, and offer new insight into possible changes in volcanic activity during periods of long-term changes in global sea level.

  10. 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.

  11. Explosive Eruptions of Kamchatkan Volcanoes in 2012 and Danger to Aviation

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Strong explosive eruption of volcanoes is the most dangerous for aircraft because in a few hours or days in the atmosphere and the stratosphere can produce about several cubic kilometers of volcanic ash and aerosols. Ash plumes and the clouds, depending on the power of the eruption, the strength and wind speed, can travel thousands of kilometers from the volcano for several days, remaining hazardous to aircraft, as the melting temperature of small particles of ash below the operating temperature of jet engines. There are 30 active volcanoes in the Kamchatka and 6 active volcanoes in the Northern Kuriles, and 4 of them continuously active. In 2012 seven strong explosive eruptions of the Kamchatkan and the Northern Kuriles volcanoes Sheveluch, Bezymianny, Kizimen, Tolbachik, Klyuchevskoy, and Karymsky took place. In addition, higher fumarolic activity of Gorely volcano was observed. 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 2012: on January 22-23; on March 16-17; March 25-30 - June 03; and on September 18: ash plumes rose up to 10 km a.s.l. and extended about 200-2000 km to the different directions of the volcano. The eruptive activity of Bezymianny volcano began since 1955, and is continuing at present as growth of the lava dome. Two paroxysmal explosive phases of the eruption occurred on March 08 and September 01: ash plumes rose up to 8-12 km a.s.l. and extended about 1500 km to the east-north-east of the volcano. Eruption of Kizimen volcano began on December 09, 2010, and continues. Strong explosive eruption began in mid-December, 2010, - ash plumes rose up to 10 km a.s.l. and extended > 800 km from the volcano. There are several stages of the eruption: explosive (from 09 December 2010 to mid-January 2011); explosive-effusive (mid-January to mid-June 2011); effusive (mid-January 2011 to September 2012). Extrusive-effusive phase of eruption

  12. Kimberlite ascent and eruption.

    PubMed

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

    2007-12-13

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

  13. 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.

  14. Eruption of Pele

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The eruption of Pele on Jupiter's moon Io. The volcanic plume rises 300 kilometers above the surface in an umbrella-like shape. The plume fallout covers an area the size of Alaska. The vent is a dark spot just north of the triangular-shaped plateau (right center). To the left, the surface is covered by colorful lava flows rich in sulfur.

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

    NASA Astrophysics Data System (ADS)

    Welch, M.; Schmidt, D. A.

    2014-12-01

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

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

    USGS Publications Warehouse

    Adams, N.K.; Houghton, B.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.

  17. 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

  18. 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.

  19. Late Holocene Eruptions of Mount Rainier, Washington

    NASA Astrophysics Data System (ADS)

    Vallance, J. W.; Sisson, T. W.; Gardner, C. A.; McGeehin, J. P.; Champion, D. E.; Byman, J. A.

    2001-12-01

    Detailed stratigraphy, more than 20 radiocarbon ages, and paleomagnetic secular variation measurements indicate that eruptions of Mount Rainier clustered in three major periods during the past 3000 years. Products include a plinian fall deposit, several vulcanian falls, several fine ash falls that are associated with block-and-ash flows, and lahars that descended all major drainages that head on the volcano. Tephra layers are of two types: vesicle rich (chiefly pumice lapilli, scoria, and ash) and vesicle poor (chiefly fine-grained glass and lithic fragments). Pumice and glass shards in vesicle-rich deposits are microlite-poor and derive from explosive eruptions. Glass shards in vesicle-poor ashes have variable microlite contents and derive from minor explosions, or from ash clouds that billow up from block-and-ash pyroclastic flows. These findings contrast with those of previous studies that document only two eruptions, each associated with a pumiceous tephra layer, during the last 3000 years. The oldest eruptive period, called Summerland, began after 2700 cal yr BP with a vesicle-poor tephra and a collapse of hydrothermally altered rock on the west flank of the volcano that generated the Round Pass mudflow. Lava flows, fine ash falls and a pyroclastic flow erupted ca 2400 to 2500 cal yr BP. Intermittent eruptions produced more fine-grained ash falls, a possible pyroclastic flow and more lahars, then culminated in the plinian "C" fall to the NE and large lahars that flowed south, southeast, and west about 2200 cal yr BP. The Summerland period ended before 1600 cal yr BP with minor fall deposits and lahars. About 1000 cal yr BP, the Deadman Flat eruptions produced large lahars that contain distinctive prismatically-jointed glassy clasts, interpreted as juvenile components from pyroclastic flows, and co- ignimbrite ash in the headwaters of the White River. The lahars descended valleys to the NE and flowed 100 km to Puget Sound. Aggradation shortly after emplacement

  20. 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.

  1. 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.

  2. Interdisciplinary Studies of Eruption at Chaitén Volcano, Chile

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

    High-silica rhyolite magma fuels Earth's largest and most explosive eruptions. Recurrence intervals for such highly explosive eruptions are in the 100- to 100,000­year time range, and there have been few direct observations of such eruptions and their immediate impacts. Consequently, there was keen interest within the volcanology community when the first large eruption of high-silica rhyolite since that of Alaska's Novarupta volcano in 1912 began on 1 May 2008 at Chaitén volcano, southern Chile, a 3-kilometer­diameter caldera volcano with a prehistoric record of rhyolite eruptions [Naranjo and Stern, 2004; Servicio Nacional de Geología y Minería (SERNAGEOMIN), 2008; Carn et al., 2009; Castro and Dingwell, 2009; Lara, 2009; Muñoz et al., 2009]. Vigorous explosions occurred through 8 May 2008, after which explosive activity waned and a new lava dome was extruded.

  3. Crustal deformation associated with the 2011 Shinmoe-dake eruption as observed by tiltmeters and GPS

    NASA Astrophysics Data System (ADS)

    Ueda, Hideki; Kozono, Tomofumi; Fujita, Eisuke; Kohno, Yuhki; Nagai, Masashi; Miyagi, Yousuke; Tanada, Toshikazu

    2013-06-01

    The National Research Institute for Earth Science and Disaster Prevention (NIED) developed volcano observation stations at the Kirishima volcanic group in 2010. The stations observed remarkable crustal deformation and seismic tremors associated with the Shinmoe-dake eruption in 2011. The major eruptive activity began with sub-Plinian eruptions (January 26) before changing to explosive eruptions and continuous lava effusion into the summit crater (from January 28). The observation data combined with GEONET data of GSI indicated a magma chamber located about 7 km to the northwest of Shinmoe-dake at about 10 km depth. The tiltmeter data also quantified detailed temporal volumetric changes of the magma chamber due to the continuous eruptions. The synchronized tilt changes with the eruptions clearly show that the erupted magma was supplied from the magma chamber; nevertheless, the stations did not detect clear precursory tilt changes and earthquakes showing ascent of magma from the magma chamber just before the major eruptions. The lack of clear precursors suggests that magma had been stored in a conduit connecting the crater and the magma chamber prior to the beginning of the sub-Plinian eruptions.

  4. 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.

  5. Geology and eruptive mechanisms of Masaya Caldera Complex, Nicaragua

    SciTech Connect

    Williams, S.N.

    1983-01-01

    Results of detailed geologic field mapping and analysis of eruptive mechanisms at Masaya Caldera Complex, Nicaragua are presented. Eruptions began at least 50,000 and possibly 460,000 y.b.p. The Las Sierras Formation, regarded as Plio-Pleistocene in age, forms the local basement. A central vent of group or vents in the developing Masaya volcanic complex produced diverse deposits, all of basaltic composition. Eruption of a pyroclastic flow-surge sequence at 2250-6500 y.b.p. culminated in wholesale collapse of a caldera with a volume of 15.3 km/sup 3/. The bulk volume of the ignimbrite is 2.2-3.4 kkm/sup 3/ and the surge deposit is 4.9-5.5 km/sup 3/. Pre-historic lava production rates of 1.9-5.5 x 10/sup 6/ m/sup 3//year are similar to rates at other volcanoes but 26-76 times greater than the historic rate of production. The average lava effusion rate of 32 m/sup 3//sec during the 1772 eruption is at least an order of magnitude greater than observed effusion rates at other Central American volcanoes, and helps explain the unusual shield-like morphology of the volcano. Pyroclastic eruptions of several types have played an important role in the evolution of the volcano. Fissure-type eruptions, unknown elsewhere in Central America, have created numerous ash and scoria deposits. Two widespread scoria-fall deposits, locally known as the Fontana Lapilli an San Judas Formation, are the first documented plinian airfall deposts of basaltic composition. The Masaya-type caldera is redefined as a caldera associated with voluminous explosive eruptions of much less than 100 km/sup 3/ of mafic magma from a summit vent.

  6. 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.

  7. 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.

  8. 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…

  9. 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.

  10. Models of volcanic eruption hazards

    SciTech Connect

    Wohletz, K.H.

    1992-06-01

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

  11. Models of volcanic eruption hazards

    SciTech Connect

    Wohletz, K.H.

    1992-01-01

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

  12. How nonimaging optics began

    NASA Astrophysics Data System (ADS)

    Winston, Roland

    2016-09-01

    Classical optics was traditionally the mapping of point sources by lenses, mirrors and occasionally holograms , i.e. making an image. The subject has had many famous scientists associated with it; Fermat, Huygens, Descartes, Hamilton just to name a few. By the mid 20th Century it was a well-developed field as exemplified by such luminaries as Walter T. Welford, Emil Wolf and many others. The theory of aberrations which addresses the imperfections of the mapping codified the state of the art. Then arose the need to collect energy, not just images. To the author's knowledge it can be traced back to WWII Germany with collection of infra-red radiation (the work by D. E. Williamson, was not published until 1952). The radiation collector, a simple right-circular cone, was a harbinger of things to come.

  13. Erupted complex odontoma delayed eruption of permanent molar.

    PubMed

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

    2013-01-01

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

  14. Will Teide erupt again?

    NASA Astrophysics Data System (ADS)

    Marti, Joan; Geyer, Adelina

    2016-04-01

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

  15. Geological aspects of the 2003 2004 eruption of Anatahan Volcano, Northern Mariana Islands

    NASA Astrophysics Data System (ADS)

    Nakada, Setsuya; Matsushima, Takeshi; Yoshimoto, Mitsuhiro; Sugimoto, Takeshi; Kato, Teruyuki; Watanabe, Tsuyoshi; Chong, Ramon; Camacho, Juan T.

    2005-08-01

    Anatahan Volcano, Northern Mariana Islands, began erupting in May-June 2003. A series of subplinian explosive eruptions of andesite magma began at the Eastern Crater in the eastern part of the summit caldera on the evening of 10 May. Brown tephra was sent mainly westward by strong winds. Small-scale pyroclastic surges were discharged eastward outside the caldera in late May. An andesite lava dome that had once filled the inner crater was fragmented by phreatomagmatic explosions in the middle of June. The phreatomagmatic explosions probably occurred due to interaction of the magma head with groundwater around the crater, and abundant very fine ash ("gray tephra") was discharged within the caldera and over most of the island. The volume of eruption products of the May-June eruption was estimated to be 1.4 × 10 7 m 3 dense-rock-equivalent. Erupted pumices and lava are aphyric andesite and are variously colored depending on their vesicularity. The SiO 2 contents of erupted materials decreased slightly with time. The fine gray ash is depleted in alkalies, probably due to leaching by acid hydrothermal fluids during explosions. Seismic activity resumed in late March 2004, and small strombolian-like explosions were repeated in May and June 2004. About half of the inner crater was filled with new scoria and lava.

  16. 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.

  17. Southern Africa

    Atmospheric Science Data Center

    2013-04-16

    ... tip of South Africa is at the bottom of the image, and Zambia is at the top. Distinctive features about a third of the way from the ... MISR Team. Aug 25, 2000 - South Africa to Zambia including the Okavango Delta. project:  MISR ...

  18. Nyamuragira Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  19. 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

  20. Redoubt Volcano: 2009 Eruption Overview

    NASA Astrophysics Data System (ADS)

    Bull, K. F.

    2009-12-01

    Redoubt Volcano is a 3110-m glaciated stratovolcano located 170 km SW of Anchorage, Alaska, on the W side of Cook Inlet. The edifice comprises a <1500-m-thick sequence of mid-Pleistocene to recent, basaltic to dacitic pyroclastic-, block-and-ash- and lava-flow deposits built on Jurassic tonalite. Magma-ice contact features are common. A dissected earlier cone underlies the E flank of Redoubt. Alunite-bearing debris flows to the SE, E and N suggest multiple flank collapses over Redoubt's history. Most recent eruptions occurred in 1966-68, and 1989-90. In March 2009, Redoubt erupted to produce pyroclastic flows, voluminous lahars, and tephra that fell over large portions of south-central Alaska. Regional and local air traffic was significantly disrupted, Anchorage airport was closed for over 12 hours, and oil production in Cook Inlet was halted for nearly five months. Unrest began in August, 2008 with reports of H2S odor. In late September, the Alaska Volcano Observatory (AVO)’s seismic network recorded periods of volcanic tremor. Throughout the fall, AVO noted increased fumarolic emissions and accompanying ice- and snow-melt on and around the 1990 dome, and gas measurements showed elevated H2S and CO2 emissions. On January 23, seismometers recorded 48 hrs of intermittent tremor and discrete, low-frequency to hybrid events. Over the next 6 weeks, seismicity waxed and waned, an estimated 5-6 million m3 of ice were lost due to melting, volcanic gas emissions increased, and debris flows emerged repeatedly from recently formed ice holes near the 1990 dome, located on the crater’s N (“Drift”) side. On March 15, a phreatic explosion deposited non-juvenile ash from a new vent in the summit ice cap just S of the 1990 dome. Ash from the explosion rose to ~4500 m above sea level (asl). The plume was accompanied by weak seismicity. The first magmatic explosion occurred on March 22. Over the next two weeks, more than 19 explosions destroyed at least two lava domes and

  1. Fixed drug eruption to tartrazine.

    PubMed

    Orchard, D C; Varigos, G A

    1997-11-01

    An 11-year-old girl with a recurrent fixed drug eruption to tartrazine on the dorsum of the left hand is presented. Oral provocation tests to both the suspected food, an artificially coloured cheese crisp, and to tartrazine were positive. This case highlights fire need to consider artificial flavours, colours and preservatives as potential culprits in classic drug eruptions.

  2. 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

  3. 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

  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. Recovery from a Giant Eruption: The Case of Eta Car

    NASA Astrophysics Data System (ADS)

    Davidson, Kris; Mehner, Andrea; Martin, John C.; Humphreys, Roberta M.

    2016-01-01

    Giant eruptions or SN Impostors are far more mysterious than "real" supernovae, because they are scarcer and because they have received far less theoretical effort. One rather special problem is the disequilibrium state of the post-eruption object. It may be partially observable by watching the star's gradual recovery; which, in principle, may offer clues to the basic instability mechanisms. So far, the only example that can be observed well enough is eta Carinae. This object's history offers tantalizing clues and counter-clues. For instance: (1) Before 2000, the recovery timescale seemed to be of order 150 years; but (2) around 2000, many attributes began to change much more rapidly; and (3) the 150-year recovery process has been punctuated by about three abrupt changes of state. This strange combination of facts has received almost no theoretical attention.

  6. Solar Eruptive Events

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2012-01-01

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

  7. An Eruption on Io

    NASA Technical Reports Server (NTRS)

    2007-01-01

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

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

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

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

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

  8. Large and small volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust; Mohajeri, Nahid

    2013-04-01

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

  9. 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

  10. Characterization of Solar Eruptions reported by EruptionPatrol

    NASA Astrophysics Data System (ADS)

    Hurlburt, Neal

    2015-04-01

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

  11. 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.

  12. Fixed drug eruption to sitagliptin.

    PubMed

    Gupta, Mrinal; Gupta, Anish

    2015-01-01

    Fixed drug eruption is a common adverse effect seen with various drugs notably antibiotics, antiepileptics and non-steroidal anti-inflammatory drugs. Herein we report a case of Sitagliptin induced fixed drug eruption in a 46 year old female who developed circumscribed, erythematous macules all over the body within one week of initiation of Sitagliptin. The lesions resolved with residual hyperpigmentation on cessation of the drug. The diagnosis was confirmed by an oral provocation test which led to a reactivation of the lesions. To the best of our knowledge, this is the first case of fixed drug eruption to Sitagliptin reported in the literature.

  13. Fixed drug eruption to propofol.

    PubMed

    Allchurch, L G V; Crilly, H

    2014-11-01

    We present a case of fixed drug eruption to propofol following a series of sedations of a patient for a number of day case procedures. The patient experienced oedema and blistering of his penis, increasing in severity and duration following each subsequent exposure. The diagnosis was confirmed by punch biopsy following an intravenous challenge test with propofol. Whilst reports of fixed drug eruptions to anaesthetic induction agents are uncommon, a number of drugs used commonly by anaesthetists are known triggers. We discuss fixed drug eruptions in relation to anaesthetic practice, aiming to raise awareness of this adverse drug reaction.

  14. Episode 49 of the Pu'u 'O'o-Kupaianaha 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 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. ?? 1995 Springer-Verlag.

  15. 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.

  16. Kamchatkan Volcanoes Explosive Eruptions in 2014 and Danger to Aviation

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    There are 30 active volcanoes in the Kamchatka, and several of them are continuously active. In 2014, three of the Kamchatkan volcanoes - Sheveluch, Karymsky and Zhupanovsky - had strong and moderate explosive eruptions. Moderate gas-steam activity was observing of Klyuchevskoy, Bezymianny, Avachinsky, Koryaksky, Gorely, Mutnovsky and other volcanoes. Strong explosive eruption of volcanoes is the most dangerous for aircraft because in a few hours or days in the atmosphere and the stratosphere can produce about several cubic kilometers of volcanic ash and aerosols. Ash plumes and the clouds, depending on the power of the eruption, the strength and wind speed, can travel thousands of kilometers from the volcano for several days, remaining hazardous to aircraft, as the melting temperature of small particles of ash below the operating temperature of jet engines. The eruptive activity of Sheveluch Volcano began since 1980 (growth of the lava dome) and is continuing at present. Strong explosive events of the volcano occurred in 2014: on January 08 and 12, May 12, September 24, October 02 and 28, November 16, 22 and 26, and December 05, 17, 26 and 29: ash plumes rose up to 9-12 km a.s.l. and extended more 900 km to the eastern and western directions of the volcano. Ashfalls occurred at Klyuchi Village (on January 12, June 11, and November 16). Activity of the volcano was dangerous to international and local aviation. Karymsky volcano has been in a state of explosive eruption since 1996. The moderate ash explosions of this volcano were noting during 2014: from March 24 till April 02; and from September 03 till December 10. Ash plumes rose up to 5 km a.s.l. and extended more 300 km mainly to the eastern directions of the volcano. Activity of the volcano was dangerous to local aviation. Explosive eruption of Zhupanovsky volcano began on June 06, 2014 and continues in January 2015 too. Ash explosions rose up to 8-10 km a.s.l. on June 19, September 05 and 07, October 11

  17. Volcanic Eruptions in Kamchatka

    NASA Technical Reports Server (NTRS)

    2007-01-01

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

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

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

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

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

  18. Futurvolc and the Bardarbunga eruption 2014-15 Iceland, success in the field and laboratory.

    NASA Astrophysics Data System (ADS)

    Hoskuldsson, Armann; Jonsdottir, Ingibjorg; Thordarson, Thor

    2016-04-01

    The Bardarbunga volcanic system in Iceland started unrest in August 2014. Seismic activity gradually build up, until magma began to be extruded on surface. The first eruption occurred on the 28th of August and was small and subglacial, the second eruption took place outside the glacier, on the 29th of August and lasted for few hours. Third and largest eruption started on early morning 31st of August. This was to be the largest eruption in Iceland since Laki eruption 1783. The eruption used the same fissure that had opened up on the 28th but was much larger. The fissure was about 2 km long with a curtain of fire along the whole fissure, curtains reaching up to 150 m into the air. The area in which the eruption took place is a glacial river outwash plain, thus relatively flat. Although the eruption site is remote, being in the highlands north of the icecap Vatnajökull, at an average altitude of some 700 m, the flat sandur plain offered a unique opportunity to combine satellite and on site observations methods. The eruption ended on the 27th of February 2015, thus lasting for almost 6 months, during this time some 1.44 km3 of lava was erupted. From day one satellite data from NOAA AVHRR, MODIS, LANDSAT 7 and 8, ASTER, EO-1 ALI, EO-1 HYPERION, SENTINEL-1, RADARSAT-2 COSMO SKYMED and TERRASAR X where collected and used in combination with onsite observation. Resulting data give unique information on the effusion rates in basaltic fissure eruptions and its evolution with time. Further information on flow behavior and cooling of basaltic lava being emplaced in a relatively flat land can be used for future and past predictions. In this talk we shall show how valuable the combination of satellite data to field observation are to be able to precisely monitor on of the largest lava eruption on earth for the past 200 years. The role of Futurevolc and preparedness involved in that work greatly enhanced and facilitated synchronization of onsite and remote data during the

  19. Tenofovir induced lichenoid drug eruption.

    PubMed

    Gupta, Mrinal; Gupta, Heena; Gupta, Anish

    2015-01-01

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

  20. Voyager 2 Jupiter Eruption Movie

    NASA Technical Reports Server (NTRS)

    2000-01-01

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

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

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

  1. Volcanology: Chronicling a medieval eruption

    NASA Astrophysics Data System (ADS)

    Ludlow, Francis

    2017-01-01

    The climatic response to the eruption of the Samalas Volcano in 1257 has been elusive. Medieval archives tell of a spatially variable reaction, with Europe and Japan experiencing severe cold compared to relative warmth in North America.

  2. An Early Holocene Eruptive Period at Mount Rainier, Washington

    NASA Astrophysics Data System (ADS)

    Byman, J.; Vallance, J. W.

    2001-12-01

    Tephrochronologic studies indicate that the Cowlitz Park eruptive period at Mount Rainier began about 7500 years ago and continued intermittently until about 6800 years ago. Stratigraphic evidence suggests that Cowlitz Park time comprises four distinct eruptive episodes, each of which occurred during a relatively brief interval. The eruptions produced subplinian falls, several small ash falls, pyroclastic flows, and lahars, the largest of which swept down the White River valley to Puget Sound lowland. Tephra layers are of two types: vesicle rich (chiefly pumice lapilli, scoria, and ash) and vesicle poor (chiefly fine-grained glass and lithic fragments). Pumice and glass shards in vesicle-rich deposits are microlite-poor and derive from larger explosive eruptions. Glass shards in vesicle-poor ashes have variable microlite contents and derive from smaller explosions, or from ash clouds that billow up from block-and-ash pyroclastic flows. Although the Pleistocene record indicates considerable effusive activity at Mount Rainier, no record remains of lavas that might have erupted during Cowlitz Park time. The oldest eruption, ca 7500 cal yr BP, produced vesicular tephra "A," distributed to the east, with a volume of 5 x 106 m3. Layer A is pumiceous, but fine-grained, glassy layers, suggestive of ash-clouds derived from pyroclastic flows, bracket it stratigraphically. About 7300 cal yr BP, within a short interval of time, a more complex eruptive episode occurred that produced a subplinian fall, at least 3 minor ash layers and an avalanche of hydrothermally altered rock on the south flank of the volcano that generated a lahar. The subplinian layer, "L," was among the most voluminous in the Holocene 30 x 106 m3 at Mount Rainier. This tephra occurs to the southeast and chiefly contains pumice along with subordinate, juvenile, lithic clasts. Related fine-to-coarse-grained ash layers derive from small explosions that occurred shortly before and after the eruption of layer L

  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. 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

  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. 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.

  7. Polymorphous light eruption.

    PubMed

    Hölzle, E; Plewig, G; von Kries, R; Lehmann, P

    1987-03-01

    Polymorphous light eruption (PLE) is a common photodermatosis of unknown etiology. It afflicts mainly fair-skinned patients, with a preponderance of young females. There is, however, no absolute restriction as to age, sex, or race. Clinical variants include the papular, vesiculo-bullous, and hemorrhagic variety, as well as plaque, erythema multiforme-like, and insect bite (strophulus)-like types. Skin lesions appear only in certain exposed areas hours or a few days after intense sunshine, and are nearly always monomorphous in the same patient. The rash subsides spontaneously within several days without leaving scars. The histopathologic picture is characteristic and shows a perivascular lymphocytic infiltrate in the upper and middle corium with subepidermal edema, vacuolization of basal cells, and spongiosis in the lower epidermis. The most important differential diagnoses are solar urticaria, photosensitive erythema multiforme, and lupus erythematosus. The action spectrum of PLE is under debate. Reproduction of skin lesions has been reported with UVB, UVA, and, rarely, visible light, with UVA probably being the most effective part of the spectrum. More important than treatment of PLE is prophylaxis. UVA- and UVB-effective sunscreens are of some help. Phototherapy and especially photochemotherapy (psoralen + UVA; PUVA) offer effective ways to decrease light sensitivity. Systemic treatment with chloroquine or beta-carotene has been disappointing.

  8. Infrasound research of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Marchetti, Emanuele; Ripepe, Maurizio

    2016-04-01

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

  9. Late Permian marine ecosystem collapse began in deeper waters: evidence from brachiopod diversity and body size changes.

    PubMed

    He, W-H; Shi, G R; Twitchett, R J; Zhang, Y; Zhang, K-X; Song, H-J; Yue, M-L; Wu, S-B; Wu, H-T; Yang, T-L; Xiao, Y-F

    2015-03-01

    Analysis of Permian-Triassic brachiopod diversity and body size changes from different water depths spanning the continental shelf to basinal facies in South China provides insights into the process of environmental deterioration. Comparison of the temporal changes of brachiopod diversity between deepwater and shallow-water facies demonstrates that deepwater brachiopods disappeared earlier than shallow-water brachiopods. This indicates that high environmental stress commenced first in deepwater settings and later extended to shallow waters. This environmental stress is attributed to major volcanic eruptions, which first led to formation of a stratified ocean and a chemocline in the outer shelf and deeper water environments, causing the disappearance of deep marine benthos including brachiopods. The chemocline then rapidly migrated upward and extended to shallow waters, causing widespread mass extinction of shallow marine benthos. We predict that the spatial and temporal patterns of earlier onset of disappearance/extinction and ecological crisis in deeper water ecosystems will be recorded during other episodes of rapid global warming.

  10. Eruptions from the Sun

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-11-01

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

  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. 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

  13. 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

  14. 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

  15. 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

  16. NeuroAIDS in Africa.

    PubMed

    Robertson, Kevin; Liner, Jeff; Hakim, James; Sankalé, Jean-Louis; Grant, Igor; Letendre, Scott; Clifford, David; Diop, Amadou Gallo; Jaye, Assan; Kanmogne, Georgette; Njamnshi, Alfred; Langford, T Dianne; Weyessa, Tufa Gemechu; Wood, Charles; Banda, Mwanza; Hosseinipour, Mina; Sacktor, Ned; Nakasuja, Noeline; Bangirana, Paul; Paul, Robert; Joska, John; Wong, Joseph; Boivin, Michael; Holding, Penny; Kammerer, Betsy; Van Rie, Annelies; Ive, Prudence; Nath, Avindra; Lawler, Kathy; Adebamowo, Clement; Royal, Walter; Joseph, Jeymohan

    2010-05-01

    In July 2009, the Center for Mental Health Research on AIDS at the National Institute of Mental Health organized and supported the meeting "NeuroAIDS in Africa." This meeting was held in Cape Town, South Africa, and was affiliated with the 5th IAS Conference on HIV Pathogenesis, Treatment and Prevention. Presentations began with an overview of the epidemiology of HIV in sub-Saharan Africa, the molecular epidemiology of HIV, HIV-associated neurocognitive disorders (HANDs), and HAND treatment. These introductory talks were followed by presentations on HAND research and clinical care in Botswana, Cameroon, Ethiopia, The Gambia, Kenya, Malawi, Nigeria, Senegal, South Africa, Uganda, and Zambia. Topics discussed included best practices for assessing neurocognitive disorders, patterns of central nervous system (CNS) involvement in the region, subtype-associated risk for HAND, pediatric HIV assessments and neurodevelopment, HIV-associated CNS opportunistic infections and immune reconstitution syndrome, the evolving changes in treatment implementation, and various opportunities and strategies for NeuroAIDS research and capacity building in the region.

  17. Stratigraphy and eruption history of pre-Green Tuff peralkaline welded ignimbrites, Pantelleria, Italy

    NASA Astrophysics Data System (ADS)

    Jordan, Nina; Branney, Mike, ,, Dr; Williams, Rebecca, ,, Dr; Norry, Mike, ,, Dr

    2013-04-01

    A revised volcanic stratigraphy is presented for the ignimbrites of Pantelleria, a peralkaline caldera volcano situated in the submerged continental rift between Africa and Sicily. The volcano has been active for ×325 ka (Mahood & Hildreth, 1986), producing eight major ignimbrites from large central eruptions, which appear to have alternated with numerous minor pumice falls and lavas from scattered local centres. The main ignimbrites can be traced along superb coastal exposures and have been logged in detail. Eruption-units have been defined by the position of palaeosols and a type section designated. Lithic breccias and pumice fall deposits associated with these major ignimbrites are interpreted as part of the same eruption overcoming correlation problems encountered by previous workers (cf Mahood & Hildreth, 1986). The ignimbrites are 2 to >20 m thick, welded to rheomorphic and cover most of the island, recording devastating, radial, high-temperature density currents. Five of the eight major ignimbrites contain lithic breccias, which have commonly been interpreted as recording caldera collapse events, but the details of individual calderas are not clear. The ignimbrites were erupted between 181 and 50 ka suggesting that the early history of the island (325 to 181 ka) differs from later stages in that only local pumice and lava-producing eruptions have occurred. This means that the amount of erupted magma increased in the later stage as the ignimbrites represent eruptions of many times the volume of the local centres. Distal peralkaline tephras have been found around the Mediterranean as far away as ~1200 km. With only this volcano erupting peralkaline compositions, it suggests that eruptions from Pantelleria have had a substantial impact on their environment. We infer that there were few Plinian events on the island, and that the distal tephras may be co-ignimbrite ashfall deposits. REFERENCES: Mahood, G.A., Hildreth, W., (1986) Bulletin of Volcanology 48, 143-172.

  18. 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.

  19. Featured Image: Solar Prominence Eruptions

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-02-01

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

  20. Textural analysis of tephra from a rhyodacitic eruption sequence, Thira (Santorini), Greece

    SciTech Connect

    Heiken, G.

    1983-01-01

    The Minoan eruption sequence of 1390 B.C. produced a minimum volume of 13 km/sup 3/ of rhyodacitic tephra (dense rock equivalent). The eruptions evolved from magmatic to phreatomagmatic and back to a mix of both processes. Thin section and scanning electron micrograph analysis of the tephra sequence provide information about eruption processes that is critical to interpretation of the field data. The eruptions began at a vent located above sea level and produced a coarse-grained Plinian pumice deposit. All later phases of the eruption involved propagating vent(s) into an older flooded caldera and flooding of the sea into a collapsing Minoan caldera. Interaction of magma and water produced fine-grained tephra that consist mostly of slightly curved, nearly flat shards and small pumice pyroclasts. These were derived during fragmentation of a heterogeneous, vesicular magma containing large compound vesicles and smaller, elongate vesicles. The vesiculated magma was thoroughly comminuted during magma-water interactions. The last eruptive phase is interpreted as having involved both magmatic and phreatomagmatic processes. Hot pyroclastic flows from this phase contained a bimodal mixture of pumice pyroclasts and finely comminuted shards.

  1. Shallow pressure sources associated with the 2007 and 2014 phreatic eruptions of Mt. Ontake, Japan

    NASA Astrophysics Data System (ADS)

    Takagi, Akimichi; Onizawa, Shin'ya

    2016-07-01

    We modeled pressure sources under Mount Ontake volcano, Japan, on the basis of global navigation satellite system (GNSS) observations of ground deformation during the time period including the 2007 and 2014 phreatic eruptions. The total change in volume in two sources below sea level in the period including the 2007 eruption was estimated from GNSS network observations to be 6 × 106 m3. Additionally, data from a GNSS campaign survey yielded an estimated volume change of 0.28 × 106 m3 in a shallower source just beneath the volcanic vents. The 2007 eruption may have been activated by magmatic activity at depth. During the 2014 eruption, the volume change at depth was very small. However, tiltmeter data indicated inflation from a shallow source that began 7 min before the eruption, representing a volume change estimated to be 0.38 × 106 m3. We infer that the potential for subsurface hydrothermal activity may have remained high after the 2007 eruption.

  2. South Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color image of South Africa was acquired on May 14, 2000, by NASA's Moderate-resolution Imaging Spectroradiometer, or MODIS. The image was produced using a combination of the sensor's 250-m and 500-m resolution visible wavelength bands. As part of the opening ceremony to begin the joint U.S.-South Africa SAFARI Field Experiment, NASA presented print copies of this image as GIFts to Dr. Ben Ngubane, Minister of Arts, Science and Technology, and Honorable Advocate Ngoaka Ramathlodi, Premier of the Northern Province, South Africa. The area shown in this image encompasses seven capital cities and a number of the region's distinctive geological features can be seen clearly. Toward the northern (top) central part of the image, the browns and tans comprise the Kalahari Desert of southern Botswana. The Tropic of Capricorn runs right through the heart of the Kalahari and the Botswanan capital city of Gaborone sits on the Limpopo River, southeast of the Kalahari. Along the western coastline of the continent is the country of Namibia, where the Namib Desert is framed against the sea by the Kaokoveld Mountains. The Namibian capital of Windhoek is obscured by clouds. Looking closely in the center of the image, the Orange River can be seen running from east to west, demarcating the boundary between Namibia and South Africa. On the southwestern corner of the continent is the hook-like Cape of Good Hope peninsula and Cape Town, the parliamentary capital of South Africa. Running west to east away from Cape Town are the Great Karroo Mountains. The shadow in this image conveys a sense of the very steep grade of the cliffs along the southern coast of South Africa. Port Elizabeth sits on the southeasternmost point of South Africa, and a large phytoplankton bloom can be seen in the water about 100 miles east of there. Moving northward along the east coast, the Drakensberg Mountains are visible. The two small nations of Lesotho and Swaziland are in this region, completely

  3. 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.

  4. 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

  5. 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.

  6. The 1631 eruption of Vesuvius

    NASA Astrophysics Data System (ADS)

    Rolandi, G.; Barrella, A. M.; Borrelli, A.

    1993-11-01

    Contemporary accounts of the violent eruption of Vesuvius in 1631 are reviewed, and recorded events are correlated with resulting volcanic deposits. Field study of the deposits in the proximal area revealed the presence of tephra falls, pyroclastic flows and lava, with subordinate surge deposits. A total volume of 1.1 km 3 (0.55 km 3 DRE) of phono-tephritic to phonolitic magma was ejected during 24 hours. The different magma compositions correspond with a transition from a lower, white, aphyric, highly vesiculated pumice (layer 1) to an upper, gray, crystal-rich, poorly vesiculated pumice (layer 3), showing reverse grading. Isopach and isopleth maps of the tephra-falls have been constructed to determine changes in the eruptive style and temporal evolution of the eruption column which reached a maximum height of 16 to 28 km. The recorded column height variations show a change in the mass discharge rate (8.9 × 10 6 kg/s to 8.2 × 10 7 kg/s) and the occurrence of pyroclastic flows during the deposition of the weakly vesiculated, dense pumice of the upper part of layer 3. Pyroclastic flows are crystal-rich and show St. Vincent-type features. The explosive phase demolished the upper part of the pre-existing cone, and debris flows invaded the southern side of the volcano. In the afternoon of December 17, 1631 an outbreak of lava flow from a southern lateral fracture system occurred, and effusion of lava continued up to midnight of December 18. Intermittent steam blasts continued to the end of December, when the eruption ended and Mount Vesuvius entered a solfataric phase. The earthquakes that had marked both the pre-eruptive and eruptive phases, continued, however, well into March 1632.

  7. 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  10. Discovery of the 2011 eruption at Axial Seamount

    NASA Astrophysics Data System (ADS)

    Chadwick, B.; Nooner, S. L.; Butterfield, D. A.; Lilley, M. D.; Clague, D. A.; Caress, D. W.; Dziak, R. P.; Haxel, J. H.

    2011-12-01

    to 200 m above the bottom. New vent sites on the 2011 lava had already been colonized by macro- and micro-fauna, just 3.5 months after the eruption. Seven instrumental moorings were in place during the 2011 eruption - 3 bottom pressure recorders (BPRs), 3 ocean bottom hydrophones (OBHs), and one remote access fluid sampler (RAS). One of each was engulfed by 2011 lava, but the four surviving ones (2 BPRs, 2 OBHs) were successfully recovered and provide an extraordinary in-situ monitoring record of the eruption. They show that the eruption began early on 6 April 2011, with a subsidence of ~ 2 m at the center of the caldera and a burst of hundreds of earthquakes that lasted about a week. The detection capability of SOSUS (the US Navy hydrophone network in the NE Pacific) is currently greatly diminished due to cable breaks, so no earthquake swarms were detected for the 2011 eruption.

  11. 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.

  12. The Monte Nuovo eruption: the only historical event of the Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    di Vito, Mauro Antonio; Arienzo, Ilenia; Buononato, Salvatore; Civetta, Lucia; Carandente, Antonio; D'Antonio, Massimo; di Renzo, Valeria; Orsi, Giovanni

    2010-05-01

    The Monte Nuovo eruption, the last event of the Campi Flegrei caldera, has been reconstructed through geological, volcanological and petrological investigations, and analyses of historical documents. The eruption, lasted one week and characterised by three vents, included three distinct phases. The main vent (MV) was located in the present crater, whereas two minor vents were along the southern (SV) and north-eastern (NEV) slopes of the Monte Nuovo tuff cone. The sequence of deposits has been subdivided in 5 members named A through E. The eruption began on September 29, 1538, at 7 p.m., and its first and main phase, lasted until the night of September 30. This phase generated almost continuous explosions mainly phreatomagmatic, producing pyroclastic density currents (pdćs) and minor short-lived, low eruption columns, which deposited members A and B. Member A, erupted in about 12 hours through the MV, forms the largest part of the cone. Phreatomagmatic explosions at the SV produced mainly pdćs which deposited Member B only in the southern sector of Monte Nuovo. Strombolian explosions at the SV and NEV deposited Member C over a narrow area. This activity was followed by a pause lasted two days. The eruption resumed on October 3 at 4 p.m. and lasted until the next night. This second phase of the eruption was characterized by a discontinuous sequence of low-energy phreatomagmatic and magmatic explosions at the MV, which deposited Member D. On October 6, at 4 p.m. explosive activity resumed and lasted few hours, mainly with low-energy magmatic explosions of a small dome, grown during the preceding two days, which produced Member E. During this phase 24 people died while climbing the slopes of the newly formed cone. The juvenile products of the Monte Nuovo eruption are phenocryst-poor rocks containing alkali feldspars and subordinate clinopyroxene and Fe-Ti oxides. The are light-coloured pumice and dark scoria fragments, and represent the most evolved magma erupted

  13. Explosive eruption of rhyodacitic magma at the Cordón-Caulle volcanic complex, southern Chile

    NASA Astrophysics Data System (ADS)

    Castro, J. M.; Schipper, C.

    2011-12-01

    After lying dormant for decades, the Cordón-Caulle volcanic complex (CCVC) reactivated again on 4 June, 2011 with an explosive eruption that produced a sustained vertical ash column reaching roughly 14,000 m a.s.l. This explosive phase produced a tephra plume that dispersed E-SE across the Chilean Patagonia into Argentina, and within a week encircled the globe prompting widespread disruption to air traffic and several airport closures. After about 3 weeks of fluctuating explosive activity, a lava flow began effusing from the same vent as the initial activity. We analyzed pumice and ash samples of the Plinian fall from 4 June for their major and trace element makeup, mineralogical characteristics, and 3D textural relationships within pyroclasts. The light beige, phenocryst-poor (<5 vol%) pumice contains plagioclase (~1mm) as its primary phase, and magnetite, orthopyroxene and clinopyroxene in sub-equal amounts. The crystals often form intergrowth clusters but may also be found separate and enclosed in highly vesicular microlite-free glass. As shown by XRF analyses on bulk pumice and ash samples collected from two localities southeast of the vent, the current eruptives comprise the following (in wt.%): SiO2 = 69.6, TiO2 = 0.70, Al2O3 = 14.3, Fe2O3 = 4.56, MnO = 0.11, MgO = 0.54, CaO = 2.3, Na2O = 5.14, K2O = 2.75, P2O5 = 0.11; and, (in ppm): Cr = 6.7, Ni = 2.3, Rb = 70.3, Sr = 163.3, Y = 51.7, Zr = 328, Ba = 702, Pb = 23.7. Interestingly, these compositions are virtually identical to those of magma erupted during 1960 and closely resemble rhyodacite erupted in 1921 from nearby vents. The primary difference between the present eruption and its recent predecessors is the much greater eruptive vigour of the current phase. Another distinction between the present and past historical eruptions is the presence of conspicuous mafic-felsic mingling textures in a small percentage (~0.5 vol%) of the current pumice. Textural and chemical analyses of the mafic blobs are

  14. HST Images Flash Ionization of Old Ejecta by the 2011 Eruption of Recurrent Nova T Pyxidis

    NASA Astrophysics Data System (ADS)

    Shara, Michael M.; Zurek, David; Schaefer, Bradley E.; Bond, Howard E.; Godon, Patrick; Mac Low, Mordecai-Mark; Pagnotta, Ashley; Prialnik, Dina; Sion, Edward M.; Toraskar, Jayashree; Williams, Robert E.

    2015-06-01

    T Pyxidis is the only recurrent nova known to be surrounded by knots of material ejected in previous outbursts. Following the eruption that began on 2011 April 14.29, we obtained seven epochs (from 4 to 383 days after eruption) of Hubble Space Telescope narrowband Hα images of T Pyx. The ionizing flash of radiation from the nova event had no discernible effect on the surrounding ejecta until at least 55 days after the eruption began. Photoionization of hydrogen located north and south of the central star was seen 132 days after the beginning of the eruption. That photoionized hydrogen recombined in the following 51 days, allowing us to determine a hydrogen atom density of at least 7× {{10}5}\\c{{m}-3}—at least an order of magnitude denser than the previously detected, unresolved [N ii] knots surrounding T Pyx. Material to the northwest and southeast was photoionized, and became bright between 132 and 183 days after the eruption began. Ninety-nine days later that northwest and southeast hydrogen had recombined. Both then (282 days after outburst) and 101 days later, we detected almost no trace of hydrogen emission around T Pyx. We determine that there is a large reservoir of previously unseen, cold diffuse hydrogen overlapping the previously detected, [N ii]-emitting knots of T Pyx ejecta. The mass of this newly detected hydrogen is model-dependent, but is is probably an order of magnitude larger than that of the [N ii] knots. We also determine that there is no significant reservoir of undetected hydrogen-rich ejecta, with density comparable to the flash-ionized ejecta we have detected, from the outer boundaries of the previously detected ejecta out to about twice that distance. The lack of distant ejecta is consistent with the Schaefer et al. scenario for T Pyx, in which the star underwent its first eruption within five years of 1866 after many millennia of quiescence, followed by the six observed recurrent nova eruptions since 1890. The lack of distant ejecta

  15. Predicting Major Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

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

  16. A MODEL FOR MAGNETICALLY COUPLED SYMPATHETIC ERUPTIONS

    SciTech Connect

    Toeroek, T.; Titov, V. S.; Mikic, Z.; Linker, J. A.; Panasenco, O.; Reeves, K. K.; Velli, M.; De Toma, G.

    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 rope 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.

  17. The largest volcanic eruptions on Earth

    NASA Astrophysics Data System (ADS)

    Bryan, Scott; Peate, David; Ukstins Peate, Ingrid; Self, Stephen; Mawby, Michael; Jerram, Dougal; Marsh, Goonie

    2010-05-01

    Large igneous provinces (LIPs) are sites of the most frequently recurring, largest volume basaltic and silicic eruptions in Earth history. The magma volumes, eruptive mechanisms, frequency and associated aerosol emissions of these eruptions are critical for understanding any interpreted climate forcing and environmental change by LIPs. The largest volume (>1000 km3 dense rock equivalent) and magnitude (>M8) eruptions produce areally extensive (104-105 km2) basaltic lava flow fields and silicic ignimbrites and 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- 2,000 km3) silicic lava flows have also been mapped out in the Mesoproterozoic Gawler Range province (Australia), an interpreted LIP remnant. Magma volumes of >1000 km3 have also been emplaced as high-level basaltic and rhyolitic sills in LIPs, and may contribute substantial aerosol emissions through shallow degassing and crystallisation. 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 ~107-108 kg s-1 producing dominantly compound pahoehoe lava flow fields. The major flood basalt eruption durations are most

  18. The largest volcanic eruptions on Earth

    NASA Astrophysics Data System (ADS)

    Ukstins Peate, I.; Bryan, S. E.; Peate, D. W.; Self, S.; Mawby, M.; Jerram, D. A.; Marsh, J.

    2010-12-01

    Large igneous provinces (LIPs) host the most frequently recurring, largest volume basaltic & silicic eruptions on Earth. Understanding magma volumes, eruptive mechanisms, frequency and aerosol emissions are critical to interpret climate forcing and environmental change. The largest volume (>1000 km3 dre) and magnitude (>M8) eruptions produce areally extensive (104-105 km2) basaltic flow fields and silicic ignimbrites that are the main building blocks of LIPs. Magma volumes >1000 km3 are also emplaced as high-level basaltic and rhyolitic sills in LIPs, and may contribute substantial aerosol emissions through shallow degassing and crystallization. Basaltic and silicic eruptions have comparable magnitudes, but silicic ignimbrite volumes may be significantly underestimated due to unrecognized and correlated, but voluminous co-ignimbrite ash deposits. Magma composition appears to be no barrier to individual eruption volume. Despite similar magnitudes, flood basaltic and silicic eruptions are very different in eruption mechanism, duration, intensity, vent configuration, and emplacement style. Flood basalts are dominantly effusive Hawaiian-Strombolian, with magma discharge rates of ~107-108 kg/s, and produce dominantly compound pahoehoe flow fields over eruption durations most likely >10 yrs. Some large-volume silicic lavas were emplaced by effusive and fissure eruptions, but discharge rates are unknown and may be up to an order of magnitude greater than those of flood basalt lavas for emplacement to be on realistic time scales (<10 years). Most silicic eruptions are moderately to highly explosive, producing co-current pyroclastic fountains (rarely Plinian) with discharge rates of 109-1011 kg/s that emplace welded to rheomorphic ignimbrites. Stratospheric ash and aerosol injections may be greater from co-ignimbrite ash clouds than eruption plumes. At present, durations for large-magnitude silicic eruptions are unconstrained. At discharge rates of 109 kg/s, equivalent to

  19. Weather radar observations of the Hekla 2000 eruption cloud, Iceland

    NASA Astrophysics Data System (ADS)

    Lacasse, C.; Karlsdóttir, S.; Larsen, G.; Soosalu, H.; Rose, W. I.; Ernst, G. G. J.

    The Hekla eruption cloud on 26-27 February 2000 was the first volcanic cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflavík international airport. Real-time radar observations of the onset, advection, and waning of the eruption cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire volcanic cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of 30 to 50 m s-1, before it reached an altitude of 11-12 km. The evolution of the reflected cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30-45 dBz portions of the reflected cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and volcanic cloud radar map are due to the fact that the greater part

  20. 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.

  1. Deformation regime and long-term precursors to eruption at large calderas: Rabaul, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Robertson, Robert M.; Kilburn, Christopher R. J.

    2016-03-01

    Eruptions at large calderas are normally preceded by variable rates of unrest that continue for decades or more. A classic example is the 1994 eruption of Rabaul caldera, in Papua New Guinea, which began after 23 years of surface uplift and volcano-tectonic (VT) seismicity at rates that changed unevenly with time by an order of magnitude. Although the VT event rate and uplift rate peaked in 1983-1985, eruptions only began a decade later and followed just 27 hours of anomalous changes in precursory signal. Here we argue that the entire 23 years of unrest belongs to a single sequence of damage accumulation in the crust and that, in 1991-1992, the crust's response to applied stress changed from quasi-elastic (elastic deformation with minor fault movement) to inelastic (deformation predominantly by fault movement alone). The change in behaviour yields limiting trends in the variation of VT event rate with deformation and can be quantified with a mean-field model for an elastic crust that contains a dispersed population of small faults. The results show that identifying the deformation regime for elastic-brittle crust provides new criteria for using precursory time series to evaluate the potential for eruption. They suggest that, in the quasi-elastic regime, short-term increases in rates of deformation and VT events are unreliable indicators of an imminent eruption, but that, in the inelastic regime, the precursory rates may follow hyperbolic increases with time and offer the promise of developing forecasts of eruption as much as months beforehand.

  2. 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

  3. 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.

  4. Eruptive viscosity and volcano morphology

    NASA Technical Reports Server (NTRS)

    Posin, Seth B.; Greeley, Ronald

    1988-01-01

    Terrestrial central volcanoes formed predominantly from lava flows were classified as shields, stratovolcanoes, and domes. Shield volcanoes tend to be large in areal extent, have convex slopes, and are characterized by their resemblance to inverted hellenic war shields. Stratovolcanoes have concave slopes, whereas domes are smaller and have gentle convex slopes near the vent that increase near the perimeter. In addition to these differences in morphology, several other variations were observed. The most important is composition: shield volcanoes tend to be basaltic, stratovolcanoes tend to be andesitic, and domes tend to be dacitic. However, important exceptions include Fuji, Pico, Mayon, Izalco, and Fuego which have stratovolcano morphologies but are composed of basaltic lavas. Similarly, Ribkwo is a Kenyan shield volcano composed of trachyte and Suswa and Kilombe are shields composed of phonolite. These exceptions indicate that eruptive conditions, rather than composition, may be the primary factors that determine volcano morphology. The objective of this study is to determine the relationships, if any, between eruptive conditions (viscosity, erupted volume, and effusion rate) and effusive volcano morphology. Moreover, it is the goal of this study to incorporate these relationships into a model to predict the eruptive conditions of extraterrestrial (Martian) volcanoes based on their morphology.

  5. Eruption conditions of spatter deposits

    NASA Astrophysics Data System (ADS)

    Rader, Erika; Geist, Dennis

    2015-10-01

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

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

    SciTech Connect

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Knox, Javon M. E-mail: ron.moore@nasa.gov

    2014-06-20

    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 that 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.

  7. Aurorae and Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    2001-06-01

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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. West Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    With its vast expanses of sand, framed by mountain ranges and exposed rock, northwestern Africa makes a pretty picture when viewed from above. This image was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra spacecraft. The Canary Islands can be seen on the left side of the image just off Africa's Atlantic shore. The light brown expanse running through the northern two thirds of the image is the Sahara Desert. The desert runs up against the dark brown Haut Atlas mountain range of Morocco in the northwest, the Atlantic Ocean to the west and the semi-arid (light brown pixels) Sahelian region in the South. The Sahara, however, isn't staying put. Since the 1960s, the desert has been expanding into the Sahelian region at a rate of up to 6 kilometers per year. In the 1980s this desert expansion, combined with over cultivation of the Sahel, caused a major famine across west Africa. Over the summer months, strong winds pick up sands from the Sahara and blow them across the Atlantic as far west as North America, causing air pollution in Miami and damaging coral reefs in the Bahamas and the Florida Keys. The white outlines on the map represent country borders. Starting at the top-most portion of the map and working clockwise, the countries shown are Morocco, Western Sahara, Mauritania, Senegal, Mali, Burkina Fasso, Nigeria, Mali (again), and Algeria. Image by Reto Stockli, Robert Simmon, and Brian Montgomery, NASA Earth Observatory, based on data from MODIS

  16. Numerical Modeling of Sound from the Eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Park, M.; Dziak, R. P.; Byun, S.; Fox, C. G.; Matsumoto, H.

    2003-12-01

    NOAA VENTS Program deployed an array of five autonomous underwater hydrophones within the SOFAR channel along the Mariana chain in February 2003 to monitor seafloor volcanic eruptions and submarine earthquakes (sponsored by NOAA's Ocean Exploration Program). These five hydrophones will be recovered in September 2003 using KORDI R/V Onnuri. The first historical eruption of Anatahan volcano in the Mariana Islands began on 10 May 2003. It is expected that the hydrophone data will include the hydroacoustic records of the eruption of Anatahan Volcano. The signals recorded from the eruption will be numerically modeled using a T-wave excitation mechanism developed from the mode scattering theory of Park et al. (2001). They found that scattering from the rough seabottom converts the acoustic energy of seafloor earthquakes from the directly excited ocean crustal/water column modes to the propagating acoustic modes of T-waves, and developed an algorithm to numerically model oceanic earthquake's T-waves. We modified this numerical model of Park et al. (2001) to predict the T-waves generated from volcanic sources by adopting a buried magmatic pipe model (Chouet, 1985). We derived a moment-tensor representation of a volcano-seismic source that is governed by the geometry of the source and the physical properties of magma. Numerical modeling of the sound from the eruption requires us to determine governing factors such as the pipe radius and magma viscosity that will enable us to grasp the inward nature of Anatahan volcano.

  17. Volcanism in Eastern Africa

    NASA Technical Reports Server (NTRS)

    Cauthen, Clay; Coombs, Cassandra R.

    1996-01-01

    In 1891, the Virunga Mountains of Eastern Zaire were first acknowledged as volcanoes, and since then, the Virunga Mountain chain has demonstrated its potentially violent volcanic nature. The Virunga Mountains lie across the Eastern African Rift in an E-W direction located north of Lake Kivu. Mt. Nyamuragira and Mt. Nyiragongo present the most hazard of the eight mountains making up Virunga volcanic field, with the most recent activity during the 1970-90's. In 1977, after almost eighty years of moderate activity and periods of quiescence, Mt. Nyamuragira became highly active with lava flows that extruded from fissures on flanks circumscribing the volcano. The flows destroyed vast areas of vegetation and Zairian National Park areas, but no casualties were reported. Mt. Nyiragongo exhibited the same type volcanic activity, in association with regional tectonics that effected Mt. Nyamuragira, with variations of lava lake levels, lava fountains, and lava flows that resided in Lake Kivu. Mt. Nyiragongo, recently named a Decade volcano, presents both a direct and an indirect hazard to the inhabitants and properties located near the volcano. The Virunga volcanoes pose four major threats: volcanic eruptions, lava flows, toxic gas emission (CH4 and CO2), and earthquakes. Thus, the volcanoes of the Eastern African volcanic field emanate harm to the surrounding area by the forecast of volcanic eruptions. During the JSC Summer Fellowship program, we will acquire and collate remote sensing, photographic (Space Shuttle images), topographic and field data. In addition, maps of the extent and morphology(ies) of the features will be constructed using digital image information. The database generated will serve to create a Geographic Information System for easy access of information of the Eastem African volcanic field. The analysis of volcanism in Eastern Africa will permit a comparison for those areas from which we have field data. Results from this summer's work will permit

  18. Volcanic eruptions and solar activity

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

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

  19. The 1883 eruption of Krakatau

    NASA Technical Reports Server (NTRS)

    Self, S.; Rampino, M. R.

    1981-01-01

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

  20. 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

  1. Filament Eruption without Coronal Mass Ejection

    NASA Technical Reports Server (NTRS)

    Choudhary, Debi Prasad; Moore, Ronald L.

    2003-01-01

    We report characteristics of quiescent filament eruptions that were not associated with coronal mass ejections (CMEs). We examined 12 quiescent filament eruptions, each of which was located far from disk center (20.7 R(sub sun)) in diffuse remnant magnetic fields of decayed active regions, was well observed in full-disk movies in Ha and Fe XI, and had good coronagraph coverage. Of the 12 events, 9 were associated with CMEs and 3 were not. Even though the two kinds of eruption were indistinguishable in their magnetic setting and in the eruptive motion of the filament in the Ha movies, each of the CME-producing eruptions produced a two-ribbon flare in Ha and a coronal arcade and/or two-ribbon flare in Fe XII, and each of the non-CME-producing eruptions did not. From this result, and the appearance of the eruptive motion in the Fe XII movies, we conclude that the non-CME-associated filament eruptions are confined eruptions like the confined filament eruptions in active regions.

  2. Observed Aspects of Reconnection in Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Moore, Ronald L.; Sterling, Alphonse C.; Gary, G. Allen; Cirtain, Jonathan W.; Falconer, David A.

    2011-10-01

    The observed magnetic field configuration and signatures of reconnection in the large solar magnetic eruptions that make major flares and coronal mass ejections and in the much smaller magnetic eruptions that make X-ray jets are illustrated with cartoons and representative observed eruptions. The main reconnection signatures considered are the imaged bright emission from the heated plasma on reconnected field lines. In any of these eruptions, large or small, the magnetic field that drives the eruption and/or that drives the buildup to the eruption is initially a closed bipolar arcade. From the form and configuration of the magnetic field in and around the driving arcade and from the development of the reconnection signatures in coordination with the eruption, we infer that (1) at the onset of reconnection the reconnection current sheet is small compared to the driving arcade, and (2) the current sheet can grow to the size of the driving arcade only after reconnection starts and the unleashed erupting field dynamically forces the current sheet to grow much larger, building it up faster than the reconnection can tear it down. We conjecture that the fundamental reason the quasi-static pre-eruption field is prohibited from having a large current sheet is that the magnetic pressure is much greater than the plasma pressure in the chromosphere and low corona in eruptive solar magnetic fields.

  3. 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

  4. Reprint of "Seismic monitoring of the Plosky Tolbachik eruption in 2012-2013 (Kamchatka Peninsula Russia)"

    NASA Astrophysics Data System (ADS)

    Senyukov, S. L.; Nuzhdina, I. N.; Droznina, S. Ya.; Garbuzova, V. T.; Kozhevnikova, T. Yu.; Sobolevskaya, O. V.; Nazarova, Z. A.; Bliznetsov, V. E.

    2015-12-01

    The active basaltic volcano Plosky Tolbachik (Pl. Tolbachik) is located in the southern part of the Klyuchevskoy volcano group on the Kamchatka Peninsula. The previous 1975-1976 Great Tolbachik Fissure Eruption (1975-1976 GTFE) occurred in the southern sector of Pl. Tolbachik. It was preceded by powerful earthquakes with local magnitudes between 2.5 and 4.9 and it was successfully predicted with a short-term forecast. The Kamchatka Branch of Geophysical Survey (KBGS) of the Russian Academy of Science (RAS) began to publish the results of daily seismic monitoring of active Kamchatka volcanoes on the Internet in 2000. Unlike the 1975-1976 GTFE precursor, (1) seismicity before the 2012-2013 Tolbachik Fissure Eruption (2012-2013 TFE) was relatively weak and earthquake magnitudes did not exceed 2.5. (2) Precursory earthquake hypocenters at 0-5 km depth were concentrated mainly under the southeastern part of the volcano. (3) The frequency of events gradually increased in September 2012, and rose sharply on the eve of the eruption. (4) According to seismic data, the explosive-effusive 2012-2013 TFE began at ~ 05 h 15 min UTC on November 27, 2012; the outbreak occurred between the summit of the Pl. Tolbachik and the Northern Breakthrough of the 1975-1976 GTFE. (5) Because of bad weather, early interpretations of the onset time and the character of the eruption were made using seismological data only and were confirmed later by other monitoring methods. The eruption finished in early September 2013. This article presents the data obtained through real-time seismic monitoring and the results of retrospective analysis, with additional comments on the future monitoring of volcanic activity.

  5. Ice-volcano interactions during the 2010 Eyjafjallajökull eruption, as revealed by airborne imaging radar

    NASA Astrophysics Data System (ADS)

    Magnússon, E.; Gudmundsson, M. T.; Roberts, M. J.; Sigurã°Sson, G.; HöSkuldsson, F.; Oddsson, B.

    2012-07-01

    During the eruption of the ice-covered Eyjafjallajökull volcano, a series of images from an airborne Synthetic Aperture Radar (SAR) were obtained by the Icelandic Coast Guard. Cloud obscured the summit from view during the first three days of the eruption, making the weather-independent SAR a valuable monitoring resource. Radar images revealed the development of ice cauldrons in a 200 m thick ice cover within the summit caldera, as well as the formation of cauldrons to the immediate south of the caldera. Additionally, radar images were used to document the subglacial and supraglacial passage of floodwater to the north and south of the eruption site. The eruption breached the ice surface about four hours after its onset at about 01:30 UTC on 14 April 2010. The first SAR images, obtained between 08:55 and 10:42 UTC, show signs of limited supraglacial drainage from the eruption site. Floodwater began to drain from the ice cap almost 5.5 h after the beginning of the eruption, implying storage of meltwater at the eruption site due to initially constricted subglacial drainage from the caldera. Heat transfer rates from magma to ice during early stages of cauldron formation were about 1 MW m-2 in the radial direction and about 4 MW m-2 vertically. Meltwater release was characterized by accumulation and drainage with most of the volcanic material in the ice cauldrons being drained in hyperconcentrated floods. After the third day of the eruption, meltwater generation at the eruption site diminished due to an insulating lag of tephra.

  6. An ergodic approach to eruption hazard scaling

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The complexity and indeterminacy of volcanic processes demand the use of statistical methods to analyze the expectations of the occurrence and size of future eruptions. The probability of a volcano producing potentially destructive eruptions in a given time interval may be estimated analyzing the sequence of past eruptions assuming a physically plausible process. Since the threat posed by eruptions depends on their mass or energy release (magnitude) and on their emission rate (intensity), the Volcanic Explosivity Index is a suitable measure to quantify the eruptive events, particularly considering that the largest available global catalogues use that measure. The definition of volcanic hazard is thus posed here in terms of the expected annual release of energy by eruptions in each VEI category. This concept is based on the ergodic property of a large set of volcanoes to release about the same amount of energy in each VEI category over a sufficiently large time interval. This property is however constrained to the VEI range of eruptions that constitute complete catalogues (VEI >2) in the lower end, and to the extreme eruptions that may destroy or significantly alter a volcanic system, such as the large caldera-forming eruptions (VEI < 7). In such conditions, a simple power law for eruptions at the global level relating the global rate of energy release to the eruption magnitude has been proposed as a statistical basis for eruptive event model development. Following the above mentioned arguments, we assume that a similar scaling law rules the annual rate at which energy is released by eruptions at individual volcanoes as log(EmRm)=bM+a, where Em is the energy released by eruptions in the VEI magnitude class M, and Rm is the occurrence rate of such eruptions over times ranges in which catalogues may be considered complete. The parameters b and a depend on the eruptive history of individual volcanoes, the former determining the preferred mode of the volcano to release

  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. Phreatomagmatic and water-influenced Strombolian eruptions of a small-volume parasitic cone complex on the southern ringplain of Mt. Ruapehu, New Zealand: Facies architecture and eruption mechanisms of the Ohakune Volcanic Complex controlled by an unstable fissure eruption

    NASA Astrophysics Data System (ADS)

    Kósik, S.; Németh, K.; Kereszturi, G.; Procter, J. N.; Zellmer, G. F.; Geshi, N.

    2016-11-01

    The Ohakune Volcanic Complex is a late Pleistocene tuff ring - scoria/spatter cone complex located south of Ruapehu volcano. This small-volume volcano consists of an outer E-W elongated compound tuff ring edifice, three inner scoria-spatter cones and further volcanic depressions, located on the Ohakune Fault. We quantified accurately the variations of the eruptive styles and processes through time by systematic sampling of key stratigraphic marker beds at proximal and distal locations, and the determination of grain size distribution, componentry, density and vesicularity. Using a Digital Terrain Model coupled with stratigraphic data, we also determined the spatial distribution and volume of each identified unit and individual edifices within the Ohakune Volcanic Complex. Activity began with a shallow phreatomagmatic phase characterized by an almost continuous generation of a low eruptive column, accompanied by wet pyroclastic density currents, together with the ejection of juvenile fragments and accidental lithics from the surrounding country rocks. Subsequent activity was dominated by a variety of Strombolian eruptions exhibiting differing intensities that were at times disrupted by phreatic blasts or phreatomagmatic explosions due to the interaction with external water and/or sudden changes in magma discharge rate. At least three major vent-shifting events occurred during the eruption, which is demonstrated by the truncation of the initial tuff ring and the infilling of the truncated area by several coarse grained surge units. Our study indicates that approx. 12 × 106 m3 DRE magma erupted within maximum 2.5 to 5 months through multiple vents. The erupted magma ascended from a depth of 16-18 km, and reached the surface within approximately 50 h. Alternating eruption styles, frequent vent-shifting and a variety of emplacement mechanisms inferred from the deposits of the Ohakune Volcanic Complex demonstrate the unpredictable nature of small-volume volcanism

  9. The Latest on Volcanic Eruptions and Climate

    NASA Astrophysics Data System (ADS)

    Robock, Alan

    2013-08-01

    What was the largest volcanic eruption on Earth since the historic Mount Pinatubo eruption on 15 June 1991? Was the Toba super­eruption 74,000 years ago—the largest in the past 100,000 years—responsible for a human genetic bottleneck or a 1000-year-long glacial advance? What role did small volcanic eruptions play in the reduced global warming of the past decade? What caused the Little Ice Age? Was the April 2010 Eyjafjallajökull eruption in Iceland important for climate change? What do volcanic eruptions teach us about new ideas on geoengineering and nuclear winter? These are some of the questions that have been answered since the review article by Robock [2000]. Reviews by Forster et al. [2007] and Timmreck [2012] go into some of these topics in much greater detail.

  10. Cholera: a continuous epidemic in Africa.

    PubMed

    Naidoo, A; Patric, K

    2002-06-01

    Cholera continues to plague many parts of the world, but has largely been concentrated in Africa, which contributes more than 80% of the total cases worldwide. Natural disasters, like the 2000 floods in Mozambique and the volcanic eruption in the Democratic Republic of the Congo in 2002, generally lead to new outbreaks of the disease. The refugee problem in many countries throughout the world also causes potential threats for disease outbreaks. Case fatality rates are high, and we are not anywhere near curbing new cholera epidemics, especially in Africa. It is thus imperative to renew discussions about the nature of this deadly disease, its treatment, measures for prevention and control, modes of transmission, its physical, social and economic impact, and potential solutions.

  11. How and Why Do Geysers Erupt?

    NASA Astrophysics Data System (ADS)

    Manga, M.

    2014-12-01

    Geysers are features that produce episodic eruptions of water, steam and sometimes non-condensable gases. Natural geysers are rare, with fewer than 1,000 worldwide. They are more than curiosities and popular tourist attractions: they offer a direct window into geothermal processes, and may serve as a natural small-scale laboratory to study larger-scale eruptive process such as those at volcanoes, and other self-organized, intermittent processes that result from phase separation and localized input of energy and mass. Despite > 200 years of scientific study, basic questions remain: Do eruptions begin from the bottom or top of the geyser? What controls eruption duration? Why do eruptions end? What are the required special subsurface geometries? Why are some geysers periodic, and others irregular? How and why do they respond to external influences such as weather, tides, and earthquakes? This presentation will review new insights from field studies at Lone Star geyser, Yellowstone National Park, geysers in the El Tatio geyser field, Chile, and laboratory models. At Lone Star we infer that dynamics are controlled by thermal and mechanical coupling between the conduit and a deeper, laterally-offset reservoir (called a "bubble trap" in previous studies). At El Tatio, we measured pressure and temperature within geysers over multiple eruption cycles: this data document the heating of liquid water by steam delivered from below. The laboratory experiments reveal how episodic release of steam from a bubble trap prepares a conduit for eruption and can generate a range of eruption intensities. In all cases, the eruption initiation, duration and termination are controlled by the interaction between the accumulation and transport of steam and liquid, and modulated by the geometry of the geyser's plumbing. Time series of thousands of eruptions confirm that internal processes control eruptions, with only pool geysers showing a sensitivity to air temperature; only very large stress

  12. 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)].

  13. Winter warming from large volcanic eruptions

    SciTech Connect

    Robock, A.; Mao, J.

    1992-01-01

    An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95 percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

  14. 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.

  15. Tornados and Transverse Oscillations during Prominence Eruption

    NASA Astrophysics Data System (ADS)

    Banerjee, Dipankar; Chandrashekhar, K.; Morton, Richard; Pant, Vaibhav; Datta, Ajanta

    2016-07-01

    We report and analyse different phases of a prominence eruption. The winding-unwinding of two footpoints and a tornado like swirling motion is studied. The prominence eruption is observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). This prominence eruption is associated with a CME at a central principal angle of 340 degree, according to the SOHO/LASCO CME catalogue. We can observe the prominence threads and the time distance maps reveal that the loop threads are entangled. We also study the transverse oscillations in the threads. Swirling motions after the eruptions are also quantified and its possible link with the CME kinematics is also studied

  16. Solar Eruption and Local Magnetic Parameters

    NASA Astrophysics Data System (ADS)

    Lee, Jeongwoo; Liu, Chang; Jing, Ju; Chae, Jongchul

    2016-11-01

    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) 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.

  17. 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.

  18. What Generated the Eruptive Tremor During the Bardarbunga Eruption, Iceland?

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristin S.; Jónsdóttir, Ingibjörg; Höskuldsson, Armann; Þórðarson, Þorvaldur

    2016-04-01

    The Bárðarbunga eruption in Iceland 2014/15 led to the formation of a 85 km2 big lavafield and the extrusion of ~1.5 km3 of magma. The eruption initially started for 4 hours on August 29th. It stopped but restarted on the same fissure on August 31st. We installed a seismic array on August 30th. Harmonic tremor was seen on August 31st consistent with the visual opening of the fissure and continued through February 2015. The harmonic tremor with most energy from 0.8-1.5 Hz is remarkably stable over 6 months but 3 characteristic features occur from time to time: (i) Stronger harmonic tremor bursts in the same frequency range, (ii) Stronger non-harmonic bursts with energy up to 5 Hz and (iii) Step like increases or decreases in the tremor amplitude. Seemingly uncorrelated the array results show (iv) three very stable tremor directions until mid October and (v) tremor sources moving by up to 9 km in 4 days. We compare these five seismic observations with the features of the growing lavafield and discuss the relative importance of possible tremor sources such as: a resonating conduit, boiling magma in the vent, a resonating lavafield, interactions at the edges of the lavafield and inflation of the lavafield.

  19. 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.

  20. Regional paleogeographic evolution of west Africa: Implications for hydrocarbon exploration

    SciTech Connect

    Hempton, M.R.; Rosen, M.A.; Coughlin, R.M.; Scardina, A.D.; Hagen, E.S.; Nordstrom, P.J. )

    1991-03-01

    New paleogeographic reconstructions of west African continental margins provide a regional framework to contrast differences in hydrocarbon habitat and tectonostratigraphic style. Five regional provinces are delineated: (1) Northwest Africa margin from mauritania to Sierra Leone, (2) Transform margin from Liberia to Benin, (3) Niger delta of Nigeria, Cameroon, and Equatorial Guinea, (4) South Atlantic Salt basin margin from Cameroon to Angola, and (5) Southwest Africa margin of Namibia and South Africa. Computer-constrained paleogeographic reconstructions based on exploration data depict the separation of west Africa from South and North America during the Late Triassic to the present along three rift systems. In northwest Africa rifting began in the Late Triassic associated with the opening of the Central Atlantic. In southwest Africa rifting began between the southern tips of Africa and South America in the Early Cretaceous (Valanginian) and propagated northward to the Benue Trough, a broad zone of left-lateral shear and extensional basins that began to open in the Aptian. Between these two rift systems, the Transform margin rift system initiated in the Early Cretaceous (Barremain) as a wrench-fault dominated eastward extension of the Proto-Caribbean ocean that propagated to the Benue Trough by the middle Albian. The most important variables affecting the tectonostratigraphic and hydrocarbon evolution of the west African margins include (1) the geometry, kinematics, and duration of rifting; (2) distribution of rift basins relative to paleoclimate zones (which affects the deposition of lacustrine source rocks and evaporites while influencing the type and quantity of sediment derived from land); (3) sea-level fluctuations; and (4) distribution of deltaic and turbiditic depocenters.

  1. Regional paleogeographic evolution of West Africa: Implications for hydrocarbon exploration

    SciTech Connect

    Hempton, M.R. )

    1993-11-01

    New paleogeographic reconstructions of west African continental margins provide a regional framework to contrast differences in hydrocarbon habitat and tectonostratigraphic style. The framework consists of five regional provinces: (1) northwest Africa margin from Mauritania to Sierra Leone, (2) transform margin from Libera to Benin, (3) Niger Delta of Nigeria, Cameroon, and equatorial Guinea, (4) South Atlantic Salt Basin margin from Cameroon to Angola, and (5) southwest Africa margin of Namibia and South Africa. Computer-constrained paleogeographic reconstructions based on exploration data depict the separation of west Africa from South and North America along three rift systems during the Late Triassic to the Holocene. In northwest Africa, rifting began in the Late Triassic associated with the opening of the central Atlantic. In southwest Africa, rifting began between the southern tips of Africa and South America in the Early Cretaceous and propagated northward to the Benue trough, a broad zone of left-lateral shear and extensional basins that began to open in the Aptian. Between these two rift systems, the transform margin rift system initiated in the Early Cretaceous (Barremian) as a wrench-fault-dominated eastward extension of the Proto-Caribbean ocean that propagated to the Benue trough by the middle Albian. The most important variables affecting the tectonostratigraphic and hydrocarbon evolution of the west African margins include (1) the geometry, kinematics, and duration of rifting, (2) distribution of rift basins relative to paleoclimate zones (which affects the deposition of lacustrine source rocks and evaporites while influencing the type and quantity of sediment derived from land), (3) sea level fluctuations, and (4) distribution of deltaic and turbiditic depocenters.

  2. Explosive Eruptions of Kamchatkan Volcanoes in 2013 and Danger to Aviation

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    There are 30 active volcanoes in the Kamchatka, and three of them (Sheveluch, Klyuchevskoy, and Karymsky) continuously active. In 2013, five of the Kamchatkan volcanoes - Sheveluch, Klyuchevskoy, Karymsky, Zhupanovsky, and Mutnovsky - had strong and moderate explosive eruptions. Strong explosive eruption of volcanoes is the most dangerous for aircraft because in a few hours or days in the atmosphere and the stratosphere can produce about several cubic kilometers of volcanic ash and aerosols. Ash plumes and the clouds, depending on the power of the eruption, the strength and wind speed, can travel thousands of kilometers from the volcano for several days, remaining hazardous to aircraft, as the melting temperature of small particles of ash below the operating temperature of jet engines. The eruptive activity of Sheveluch Volcano began since 1980 (growth of the lava dome) and is continuing at present. Strong explosive events of the volcano occurred in 2013: on June 26, on October 18, and on December 03: ash plumes rose up to 10 km a.s.l. and extended about 200-400 km, respectively, to the south-west, south-southeast, and north of the volcano. A form of pyroclastic flow deposits with run-out 12 km accompanied these explosive eruptions. Ashfalls occurred at Klyuchi Village (on June 26) and Ivashka Village (on December 03). Activity of the volcano was dangerous to international and local aviation. Klyuchevskoy volcano had two eruptions in 2013: moderate Strombolian explosive eruption from October 14, 2012, till January 15, 2013; and strong Strombolian-Vulcanian explosive and effusive eruption from August 15, 2013, till December 20, 2013. There were four lava flows to effuse on the north-west, west and south-western volcanic flanks. Probably a flank eruption began at the pass between Klyuchevskoy volcano and Kamen volcano on October 06. Culmination of strong Vulcanian explosive activity of the volcano occurred on October 15-20: ash column rose up to 10-12 km a.s.l. and

  3. Herculaneum: Clues to Vesuvius eruption

    NASA Astrophysics Data System (ADS)

    Richman, Barbara T.

    More than 80 skeletons have been unearthed in the ancient Mediterranean town of Herculaneum, west of Italy's Mount Vesuvius. This anthropological find corroborates a reinterpretation by three University of Rhode Island scientists of the sequence of the August A.D. 79 eruption of Vesuvius. In addition, the discovery is the first proof that large numbers of people perished as they tried to flee from the eruption, estimated to have been about 10 times more powerful than the May 1980 Mount St. Helens blast.‘Who says dead men don't talk? Their bones have something to say about them and their everyday lives,’ says Sara C. Bisel, a physical anthropologist who analyzed the skeletons. Among the remains are a cluster of skeletons from six adults, four children, and two infants trying to shield themselves from the volcanic onslaught; the skeleton of a sailor, still clutching an oar, lying on his back beside an 8-m-long capsized boat; a woman whose now bony hand was still graced with gem-encrusted gold rings; and a soldier (see Figure 1). From these and other finds the anthropological team was able to discern that the ancient Romans, on average, were shorter than modern citizens and, judging from the condition of some of the teeth, probably had a low-sugar diet.

  4. Jupiter Eruptions Captured in Infrared

    NASA Technical Reports Server (NTRS)

    2008-01-01

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

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

    This infrared image shows two bright plume eruptions obtained by the NASA Infrared Telescope Facility on April 5, 2007.

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

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

  5. The September 1988 intracaldera avalanche and eruption at Fernandina volcano, Galapagos Islands

    NASA Astrophysics Data System (ADS)

    Chadwick, William W.; de Roy, Tui; Carrasco, Alfredo

    1991-05-01

    During 14 16 September 1988, a large intracaldera avalanche and an eruption of basaltic tephra and lava at Fernandina volcano, Galapagos, produced the most profound changes within the caldera since its collapse in 1968. A swarm of eight earthquakes ( m b 4.7 5.5) occurred in a 14 h period on 24 February 1988 at Fernandina, and two more earthquakes of this size followed on 15 April and 20 May, respectively. On 14 September 1988, another earthquake ( m b 4.6) preceded a complex series of events. A debris avalanche was generated by the failure of a fault-bounded segment of the east caldera wall, approximately 2 km long and 300 m wide. The avalanche deposit is up to 250 m thick and has an approximate volume of 0.9 km3. The avalanche rapidly displaced a preexisting lake from the southeast end of the caldera floor to the northwest end, where the water washed up against the lower part of the caldera wall, then gradually seeped into the avalanche deposit and was completely gone by mid-January 1989. An eruption began in the caldera within about 1 2 h of the earthquake, producing a vigorous tephra plume for about 12 h, then lava flows during the next two days. The eruption ended late on 16 September. Most of the eruptive activity was from vents on the caldera floor near the base of the new avalanche scar. Unequivocal relative timing of events is difficult to determine, but seismic records suggest that the avalanche may have occurred 1.6 h after the earthquake, and field relations show that lava was clearly erupted after the avalanche was emplaced. The most likely sequence of events seems to be that the 1988 feeder dike intruded upward into the east caldera wall, dislocated the unstable wall block, and triggered the avalanche. The avalanche immediately exposed the newly emplaced dike and initiated the eruption. The exact cause of the earthquakes is unknown.

  6. 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

  7. Rapid forced eruption: a case report and review of forced eruption techniques.

    PubMed

    Durham, Timothy M; Goddard, Thomas; Morrison, Scott

    2004-01-01

    This article reviews the infrequently utilized treatment method of forced eruption and how it can serve as an alternative to the sacrifice of the natural root system. Forced eruption can preserve the natural root system and related periodontal architecture, resulting in years of additional service for the patient. It also can maintain adjacent tooth structure while retaining the option for future implant reconstruction. Given the reported success of forced eruption, the technique requires greater attention and increased application among dentists. A case of forced eruption in the anterior maxilla utilizing a removable device is described. An overview of forced eruption technique also is provided.

  8. The effects of colony-stimulating factor-1 on tooth eruption in the toothless (osteopetrotic) rat in relation to the critical periods for bone resorption during tooth eruption.

    PubMed

    Iizuka, T; Cielinski, M; Aukerman, S L; Marks, S C

    1992-08-01

    The toothless (tl) rat is an osteopetrotic mutation characterized by a generalized skeletal sclerosis, reduced bone resorption, few osteoclasts and a total absence of erupted teeth. This mutation is not cured by bone marrow transplants from normal littermates. It is known that the skeletal defects in tl rats are greatly improved after treatment with colony-stimulating factor-1 (CSF-1). This investigation concerns the effects of CSF-1 on the development and eruption of the dentition of tl rats. Untreated tl rats had no erupted teeth by 56 days after birth, and the roots of incisors and molars were severely distorted by compression against bone. The apex of the mandibular incisor did not extend past the first molar and continued growth of its apical end produced odontoma-like masses consisting of distorted dentine and enamel matrices. In addition, few osteoclasts were seen on alveolar bone surfaces surrounding the developing teeth. Mutants given CSF-1 were characterized by delayed eruption of all molars and sometimes incisors. The incidence of incisor eruption was related inversely to the age at which CSF-1 treatment began. Molars of treated tl rats had well-developed roots similar to those in normal rats. Treated mutants had numerous osteoclasts in alveolar bone and well-developed haemopoietic marrow spaces in the mandible. Histochemical staining for both tartrate-resistant acid phosphatase and tartrate-resistant acid ATPase was reduced or negligible in osteoclasts of untreated tl rats, heavy in normal osteoclasts and of intermediate intensity in CSF-1-treated mutants.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Large scale pantelleritic ash flow eruptions during the Late Miocene in central Kenya and evidence for significant environmental impact

    NASA Astrophysics Data System (ADS)

    Claessens, L.; Veldkamp, A.; Schoorl, J. M.; Wijbrans, J. R.; van Gorp, W.; Macdonald, R.

    2016-10-01

    In the area south-east of Mount Kenya, four previously unrecorded peralkaline rhyolitic (pantelleritic) ash flow tuffs have been located. These predominantly greyish welded and non-welded tuffs form up to 12 m thick units, which are sometimes characterized by a basal vitrophyre. The four flow units yielded 40Ar/39Ar ages ranging from 6.36 to 8.13 Ma, indicating a period of 1.8 Ma of pantelleritic volcanic activity during the Late Miocene in central Kenya. Tentative compositional and age correlations with other known tuff deposits suggest that the pantelleritic tuffs originally covered 40,000 km2 in central Kenya, extending much further than earlier recorded Pliocene tuffs. This newly identified magmatic phase occurred between the phonolitic flood eruptions (16-8 Ma) and the Pliocene tuff eruptions (6-4 Ma). The occurrence of multiple ash flow tuff deposits up to 150 km away from the inferred eruptive center(s) in the central sector of the Kenya Rift, indicates multi-cyclic peralkaline supereruptions during the Late Miocene. By analogy with more recent pantelleritic eruptions, the tuffs are thought to have been sulfur-rich; during eruption, they formed stratospheric aerosols, with significant environmental impact. The timing of the eruptions coincides with the shift towards more savannah-dominated environments in East Africa.

  10. It All Began with Margaret.

    ERIC Educational Resources Information Center

    Kansas Association of School Librarians, Wichita.

    The Kansas Association of School Librarians has gathered together in this booklet practical information which is both an outgrowth of Margaret Oliver's creative imagination and a tribute to her. There are short descriptions, many illustrated, of useful library gadgets, administrative procedures, processing and maintenance ideas, and equipment--all…

  11. How Our Decimal Money Began.

    ERIC Educational Resources Information Center

    Clason, Robert G.

    1986-01-01

    Discusses how the decimal monetary system was created, considering colonial currency, continental currency, money under the Articles of Confederation, and money under the Constitution. Also discusses how money is taught in arithmetic textbooks during these times. (JN)

  12. Modeling eruptive coronal magnetohydrodynamic systems with FLUX

    NASA Astrophysics Data System (ADS)

    Rachmeler, L. A.

    In this dissertation I explore solar coronal energetic eruptions in the context of magnetic reconnection, which is commonly thought to be a required trigger mechanism for solar eruptions. Reconnection is difficult to directly observe in the corona, and current numerical methods cannot model reconnectionless control cases. Thus, it is not possible to determine if reconnection is a necessary component of these eruptions. I have executed multiple controlled simulations to determine the importance of reconnection for initiation and evolution of several eruptive systems using FLUX, a numerical model that uses the comparatively new fluxon technique. I describe two types of eruptions modeled with FLUX: a metastable confined flux rope theory for coronal mass ejection (CME) initiation, and symmetrically twisted coronal jets in a uniform vertical background field. In the former, I identified an ideal magnetohydrodynamic (MHD) instability that allows metastable twisted flux rope systems to suddenly lose stability and erupt even in the absence of reconnection, contradicting previous conjecture. The CME result is in contrast to the azimuthally symmetric coronal jet initiation model, where jet-like behavior does not manifest without reconnection. My work has demonstrated that some of the observed eruptive phenomena may be triggered by non-reconnective means such as ideal MHD instabilities, and that magnetic reconnection is not a required element in all coronal eruptions.

  13. Large erupting complex odontoma: a case report.

    PubMed

    Vengal, Manoj; Arora, Honey; Ghosh, Sujoy; Pai, Keerthilatha M

    2007-03-01

    Odontomas are the most common odontogenic tumours. They are usually asymptomatic and are often discovered during routine radiography. We report a case of a large erupting complex odontoma that caused pain, infection and facial asymmetry. This case is significant as there are few reports of complex odontoma erupting in the oral cavity.

  14. Recovery From Giant Eruptions in Massive Stars

    NASA Astrophysics Data System (ADS)

    Kashi, A.; Davidson, K.; Humphreys, R. M.

    2015-12-01

    We perform radiation hydrodynamic simulations to study how very massive stars recover from giant eruptions. The post eruption star experience strong mass loss due to strong winds, driven by radial pulsations in the star*s interior, that operate by the κ-mechanism. The mass loss history obtained in our simulations resembles η Car*s history.

  15. The 1991 eruption of Hekla, Iceland

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust; Oskarsson, Niels; Gronvold, Karl; Saemundsson, Kristjan; Sigurdsson, Oddur; Stefansson, Ragnar; Gislason, Sigurdur R.; Einarsson, Pall; Brandsdottir, Bryndis; Larsen, Gudrun; Johannesson, Haukur; Thordarson, Thorvaldur

    1992-02-01

    The eruption that started in the Hekla volcano in South Iceland on 17 January 1991, and came to an end on 11 March, produced mainly andesitic lava. This lava covers 23 km2 and has an estimated volume of 0.15 km3. This is the third eruption in only 20 years, whereas the average repose period since 1104 is 55 years. Earthquakes, as well as a strain pulse recorded by borehole strainmeters, occurred less than half an hour before the start of the eruption. The initial plinian phase was very short-lived, producing a total of only 0.02 km3 of tephra. The eruption cloud attained 11.5 km in height in only 10 min, but it became detached from the volcano a few hours later. Several fissures were active during the first day of the eruption, including a part of the summit fissure. By the second day, however, the activity was already essentially limited to that segment of the principal fissure where the main crater subsequently formed. The average effusion rate during the first two days of the eruption was about 800 m3 s-1. After this peak, the effusion rate declined rapidly to 10 20 m3 s-1, then more slowly to 1 m3 s-1, and remained at 1 12 m3 s-1 until the end of the eruption. Site observations near the main crater suggest that the intensity of the volcanic tremor varied directly with the force of the eruption. A notable rise in the fluorine concentration of riverwater in the vicinity of the eruptive fissures occurred on the 5th day of the eruption, but it levelled off on the 6th day and then remained essentially constant. The volume and initial silica content of the lava and tephra, the explosivity and effusion rate during the earliest stage of the eruption, as well as the magnitude attained by the associated earthquakes, support earlier suggestions that these parameters are positively related to the length of the preceeding repose period. The chemical difference between the eruptive material of Hekla itself and the lavas erupted in its vicinity can be explained in terms of a

  16. 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.

  17. North Africa

    SciTech Connect

    Nicod, M.A.

    1981-10-01

    The total area covered by petroleum rights in the six countries described in this paper increased by more than 17% in 1980 compared to 1979. Joint venture agreements were finalized for 19 blocks over 94,000 km/sup 2/ in the Algerian venture. Although official information is scarce for Algeria and Libya, seismic activity probably increased in 1980 compared to 1979. Exploration drilling activity increased with 121 wildcats drilled compared to 93 during the previous year. This effort led to 40 discoveries, a 34.5% success ratio. Chevron was especially successful in wildcatting, with 6 oil discoveries for 8 wells drilled in the interior basins of Sudan. One Moroccan discovery can be considered as a highlight: the BRPM Meskala 101 well in the Essaouira basin found an apparently large amount of gas in Triassic sandstones. This discovery deserves special attention, since the gas has been found in Triassic pays rather than in the usual Jurassic pays in the Essaouira basin. Oil production in North Africa decreased from about 13.5% in 1980, with about 3,405,000 barrels of oil per day compared to 3,939,500 barrels of oil per day in 1979. When oil output strongly decreased in Algeria (-16.4%) and Libya (-15.6%), Tunisian production peaked at 116,287 barrels of oil per day and Egypt production also peaked at 584,148 barrels of oil per day. Total gas production in 1980 strongly declined from 44%, mostly due to the decline of the Algerian gas production. 8 figures, 40 tables.

  18. 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.

  19. Deep and shallow sources for the Lusi mud eruption revealed by surface deformation

    NASA Astrophysics Data System (ADS)

    Shirzaei, Manoochehr; Rudolph, Maxwell L.; Manga, Michael

    2015-07-01

    The Lusi mud eruption, in East Java, Indonesia, began in May 2006 and continues to the present. Previous analyses of surface deformation data suggested an exponential decay of the pressure in the mud source but did not constrain the location, geometry, and evolution of the possible source(s) of the erupting mud and fluids. To map the surface deformation, we employ multitemporal interferometric synthetic aperture radar and analyze a well-populated L-band data set acquired by the Advanced Land Observing Satellite (ALOS) between May 2006 and April 2011. We then apply a time-dependent inverse modeling scheme. Volume changes occur in two regions beneath Lusi, at 0.3-2.0 km and 3.5-4.75 km depth. The cumulative volume change within the shallow source is ~2-3 times larger than that of the deep source. The observation and model suggest that a shallow source plays a key role by supplying the erupting mud, but that additional fluids do ascend from depths >4 km on eruptive timescales.

  20. Deep and shallow sources for the Lusi mud eruption revealed by surface deformation

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Rudolph, M. L.; Manga, M.

    2015-12-01

    The Lusi mud eruption, near Sidoarjo, East Java, Indonesia, began in May 2006 and continues to the present. Previous analyses of surface deformation data suggested an exponential decay of the pressure in the mud source, but did not constrain the location, geometry and evolution of the possible source(s) of the erupting mud and fluids. To map the surface deformation, we develop and new multitrack multitemporal interferometric processing algorithm and apply it to overlapped zones of three well-populated SAR data sets, including 51 images and acquired by the ALOS L-band satellite between May 2006 and April 2011. To understand the spatiotemporal evolution of the mud and fluid sources, we then apply a time-dependent inverse modeling scheme. Volume changes occur in two regions beneath Lusi, at 0.3-2.0 km and 3.5-4.75 km depth. The cumulative volume change within the shallow source is ~2-3 times larger than that of the deep source. The observation and model suggest that a shallow source plays a key role by supplying the erupting mud, but that additional fluids do ascend from depths >4 km on eruptive timescales.

  1. 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

  2. Estimates of mass eruption rates in Icelandic eruptions 1913-2015

    NASA Astrophysics Data System (ADS)

    Tumi Gudmundsson, Magnus; Dürig, Tobias; Larsen, Gudrún

    2016-04-01

    In the period from 1913 to 2015 about 35 eruptions occurred in Iceland, although some uncertainty exists about the number of the smallest events, particularly within the ice covered regions. For the smaller events in the earlier part of the period, only order of magnitude estimates of mass eruption rates (MER) are possible, based on the approximate amount of erupted products, duration of eruption, and information on eruption plume height in some cases. After 1947 estimates are more reliable. This is not least due to the detailed observations and interpretations of Sigurdur Thorarinsson and co-workers until the early 1980s. After 1980, various observations and instrumental data, e.g. on plume height, coupled with detailed mapping by several workers of tephra fallout and lava flow extent provide a good basis for MER estimates. The most frequent events are explosive eruptions producing tephra, often basaltic phreatomagmatic eruptions. A contributing factor to the large number of explosive eruptions is unusually frequent eruptions in Hekla since 1947. Eruptions under glaciers are also common, while a majority of these become explosive as they break through the ice. For the initially subglacial eruptions ice melting rates provide the best estimate of the MER in the first and usually most powerful phase. If the whole data set is considered, the magma volumes erupted in a single eruption span three orders of magnitude, ˜0.001 km3 to 1 km3. The range of intensity is similar, with the smallest Krafla or Askja events having maximum mass eruption rates (MER) of order 10-100 tonnes/second while the most powerful ones (Hekla 1947 and Katla 1918) had MER ˜50,000 tonnes/second (˜5 x 107 kg/s). All the events with the highest MER were explosive, including Katla 1918 where initial subglacial melting caused the largest volcanogenic flood observed since the 18th century. The period 1913-2015 had no events that belong to the class of the largest observed eruptions in Iceland. In

  3. 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.

  4. 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.

  5. 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

  6. Explosive Super-eruptions: Problems and Prejudices

    NASA Astrophysics Data System (ADS)

    Self, S.

    2010-12-01

    A super-eruption is defined as one with a magma yield > 10^15 kg (magnitude (M) 8). The term has mainly been applied to large-scale, caldera and ignimbrite-forming explosive eruptions, but it can be applied to all eruptions that released > 10^15 kg of magma. For effusive volcanism, evidence suggests that individual eruptions of this size ( > ~ 370 km^3 of typical basalt or > 450 km^3 of rhyolite flood lava) arise only during periods of LIP formation. The super-eruption concept raises interesting questions about genesis and storage of magmas that feed these vast events. Deposits of major explosive eruptions are Plinian fallout, ignimbrite sheets, and co-ignimbrite ash fall. Based on earlier suggestions and evidence, widespread outflow ignimbrite (O), co-ignimbrite ash (A), and inter-caldera ignimbrite (I) are all major components of the total super-eruption deposit and may tend towards being subequal. In super-eruption deposits, the reported volume of vent-derived Plinian eruption column fallout is often a minor component of the total volume, yet in several cases (Oruanui, Taupo, 26 ka ago, M 8.1; Bishop Tuff, 760 ka, M 8.2; Bandelier (Otowi) Tuff, 1.6 Ma, M8) it is now recognized that vent-derived columns persisted for most of the eruption. Thus, distally, the ash-fall derived from co-ignimbrite ash clouds may be mixed with contemporaneous fallout from a vertical column. Some major ignimbrites have no reported associated Plinian deposit; the huge Young Toba Tuff (YTT, 74 ka, M 8.8) is a significant example. However, the very widespread Toba ash-fall deposit constitutes ~ 40 % of the total mass of magma erupted and is presumed to be co-ignimbrite. Timing of the onset of column collapse probably controls whether a recognizable Plinian deposit is laid down. All super-eruptions probably produce extensive fallout deposits, and this is generally of vent-derived and pyroclastic-flow-derived origin. Establishing the relationships between large-scale ignimbrites and their

  7. The separation of madagascar and Africa.

    PubMed

    Rabinowitz, P D; Coffin, M F; Falvey, D

    1983-04-01

    Identification of a sequence of east-west trending magnetic anomalies of Mesozoic age in the western Somali Basin helps define the position of Madagascar in the Gondwana reconstruction. The anomalies are symmetric about ancient ridge segments and are flanked to the north and south by the Jurassic magnetic quiet zone. The motion of Madagascar relative to Africa was from the north and began in the middle Jurassic, about the same time as the initial breakup of Gondwanaland. Sea-floor spreading ceased when Madagascar assumed its present position in the Early Cretaceous.

  8. Africa: Prosperous times

    SciTech Connect

    1996-08-01

    Political instability and corruption is the rule, rather than the exception, in Africa`s main producing regions, but exploration and production prospects there are bright and attractive to foreign operators. The paper discusses exploration, drilling, resource development, and production in Nigeria, Libya, Algeria, Egypt, Angola, Congo, Gabon, and Tunisia. The other countries of Africa are briefly mentioned, i.e., Cameroon, Cote D`Ivoire, South Africa, Sudan, Namibia, Equatorial Guinea, Eritrea, Zaire, Mozambique, Ghana, Niger, and Seychelles.

  9. Thermal vesiculation during volcanic eruptions.

    PubMed

    Lavallée, Yan; Dingwell, Donald B; Johnson, Jeffrey B; Cimarelli, Corrado; Hornby, Adrian J; Kendrick, Jackie E; von Aulock, Felix W; Kennedy, Ben M; Andrews, Benjamin J; Wadsworth, Fabian B; Rhodes, Emma; Chigna, Gustavo

    2015-12-24

    Terrestrial volcanic eruptions are the consequence of magmas ascending to the surface of the Earth. This ascent is driven by buoyancy forces, which are enhanced by bubble nucleation and growth (vesiculation) that reduce the density of magma. The development of vesicularity also greatly reduces the 'strength' of magma, a material parameter controlling fragmentation and thus the explosive potential of the liquid rock. The development of vesicularity in magmas has until now been viewed (both thermodynamically and kinetically) in terms of the pressure dependence of the solubility of water in the magma, and its role in driving gas saturation, exsolution and expansion during decompression. In contrast, the possible effects of the well documented negative temperature dependence of solubility of water in magma has largely been ignored. Recently, petrological constraints have demonstrated that considerable heating of magma may indeed be a common result of the latent heat of crystallization as well as viscous and frictional heating in areas of strain localization. Here we present field and experimental observations of magma vesiculation and fragmentation resulting from heating (rather than decompression). Textural analysis of volcanic ash from Santiaguito volcano in Guatemala reveals the presence of chemically heterogeneous filaments hosting micrometre-scale vesicles. The textures mirror those developed by disequilibrium melting induced via rapid heating during fault friction experiments, demonstrating that friction can generate sufficient heat to induce melting and vesiculation of hydrated silicic magma. Consideration of the experimentally determined temperature and pressure dependence of water solubility in magma reveals that, for many ascent paths, exsolution may be more efficiently achieved by heating than by decompression. We conclude that the thermal path experienced by magma during ascent strongly controls degassing, vesiculation, magma strength and the effusive

  10. Thermal vesiculation during volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Lavallée, Yan; Dingwell, Donald B.; Johnson, Jeffrey B.; Cimarelli, Corrado; Hornby, Adrian J.; Kendrick, Jackie E.; von Aulock, Felix W.; Kennedy, Ben M.; Andrews, Benjamin J.; Wadsworth, Fabian B.; Rhodes, Emma; Chigna, Gustavo

    2015-12-01

    Terrestrial volcanic eruptions are the consequence of magmas ascending to the surface of the Earth. This ascent is driven by buoyancy forces, which are enhanced by bubble nucleation and growth (vesiculation) that reduce the density of magma. The development of vesicularity also greatly reduces the ‘strength’ of magma, a material parameter controlling fragmentation and thus the explosive potential of the liquid rock. The development of vesicularity in magmas has until now been viewed (both thermodynamically and kinetically) in terms of the pressure dependence of the solubility of water in the magma, and its role in driving gas saturation, exsolution and expansion during decompression. In contrast, the possible effects of the well documented negative temperature dependence of solubility of water in magma has largely been ignored. Recently, petrological constraints have demonstrated that considerable heating of magma may indeed be a common result of the latent heat of crystallization as well as viscous and frictional heating in areas of strain localization. Here we present field and experimental observations of magma vesiculation and fragmentation resulting from heating (rather than decompression). Textural analysis of volcanic ash from Santiaguito volcano in Guatemala reveals the presence of chemically heterogeneous filaments hosting micrometre-scale vesicles. The textures mirror those developed by disequilibrium melting induced via rapid heating during fault friction experiments, demonstrating that friction can generate sufficient heat to induce melting and vesiculation of hydrated silicic magma. Consideration of the experimentally determined temperature and pressure dependence of water solubility in magma reveals that, for many ascent paths, exsolution may be more efficiently achieved by heating than by decompression. We conclude that the thermal path experienced by magma during ascent strongly controls degassing, vesiculation, magma strength and the effusive

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    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.

  12. 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.

  13. 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

  14. Satellite observations of the volcanic plume from the 23rd April 2015 eruption of Calbuco volcano

    NASA Astrophysics Data System (ADS)

    Hayer, Catherine; Carboni, Elisa; Ventress, Lucy; Povey, Adam; Grainger, Roy

    2016-04-01

    Calbuco volcano, Chile, erupted on 23rd April 2015, producing an eruption column reported to reach 17 km. The eruption was captured on the IASI NRT website (http://www.nrt-atmos.cems.rl.ac.uk/). The data were then reprocessed using the iterative optimal estimation retrieval developed by the EODG group at University of Oxford to determine the SO2 atmospheric loading and the altitude of the plume over time. The atmospheric loading was measured as 0.3 - 0.4 Tg of SO2 over the first 2 days. It is thought that the eruption was relatively ash poor, with the majority of the ash falling out within the first couple of days. The retrieved altitude of the plume is consistent with the range initially reported, with the core of the plume reaching 15 - 18 km. When the SO2 plume reached the west coast of South Africa, it was caught in a cyclonic system, causing it to remain in the same region for several days with a highly constrained core. A SO2 depletion rate and conversion time to H2SO4 are calculated from this data. The data from the IASI instruments are compared to CALIOP lidar overpasses as well as data from the MLS & OSIRIS instruments. The HYSPLIT trajectory model is used to investigate the evolution of the plume and to corroborate the altitudes retrieved by IASI.

  15. Long-term forecasting of eruption hazards: A hierarchical approach to merge analogous eruptive histories

    NASA Astrophysics Data System (ADS)

    Sheldrake, Tom

    2014-10-01

    Estimating the hazard associated with a volcanic eruption requires an understanding of previous eruptive episodes to forecast future events. This involves calculating how destructive a future eruption is likely to be by estimating the magnitude of eruptive activity and likelihood of various hazardous phenomena. Importantly though, eruptive histories for individual volcanoes can suffer from a lack of observations and thus might not be representative for all future eruption scenarios. Consequently, a methodology is developed to combine eruptive histories from multiple volcanoes into an event tree framework to inform forecasts at individual volcanoes. It is based on a hierarchical Bayesian approach in which model parameters are derived for a group of volcanoes and then updated on an individual basis. However, eruptive histories are not simply aggregated and the model allows for possible heterogeneities in eruptive regimes. Continuous probability distributions are employed to capture the relative uncertainties of both global and individual records and posterior distributions for eruption magnitudes and hazardous phenomena are computed using Markov chain Monte Carlo techniques. The model is designed to initially include no subjective judgement of probabilities but is developed so that information from other analyses can be incorporated. While this article uses the hierarchical Bayesian approach specifically for event forecasting, the methodology has the potential to be used in a wide range of problems regarding hazard assessment and for the purposes of causal inference and data reduction.

  16. The Campi Flegrei caldera: historical revision and new data on seismic crises, bradyseisms, the Monte Nuovo eruption and ensuing earthquakes (twelfth century 1582 uc(ad))

    NASA Astrophysics Data System (ADS)

    Guidoboni, Emanuela; Ciuccarelli, Cecilia

    2010-12-01

    This paper presents the results of a systematic historical study of the seismic, bradyseismic and eruptive activity of the Campi Flegrei caldera. The aim is to make a revised historical data available for accurate volcanological interpretation, supplying additional data and highlighting spurious previous data. The analysis begins with the supposed 1198 eruption, which did not actually take place. No information is available for the thirteenth and fourteenth centuries. As far as the fifteenth and sixteenth centuries are concerned, only direct sources were examined for this paper, and they include many different types of evidence. The chronological breadth of the analysis has also provided information about the seismic crises and bradyseisms prior to the eruption of 1538. The exceptional nature of this 1538 eruption attracted the attention of intellectuals, diplomats and natural philosophers, who left valuable accounts, which we have analysed, and which include many that are still available in their original manuscript form. The previous studies concerning the 1538 eruption were based on 23 (variously used) sources. We have examined 35 additional sources bringing the overall corpus of sources analysed to 58. The results provide a more precise scenario of events preceding the 1538 eruption, including bradyseismic activity starting from the end of the fifteenth century. The chronology of the phenomena described comprises the core result of this study, and has been constructed so as to clarify the time, location and impact of each event. For the 1538 eruption, a countdown is included which may also have a predictive value. For the last 36 hours before eruption began, the countdown is hour-by-hour. The effects of the eruption and earthquakes on people, structures and society are also described for Pozzuoli, Agnano and Naples. The areas where heavy materials and ash fell are likewise indicated, as well are the earth tremors felt by the population from the eruptive crisis

  17. The Campi Flegrei caldera: historical revision and new data on seismic crises, bradyseisms, the Monte Nuovo eruption and ensuing earthquakes (twelfth century 1582 AD)

    NASA Astrophysics Data System (ADS)

    Guidoboni, Emanuela; Ciuccarelli, Cecilia

    2011-08-01

    This paper presents the results of a systematic historical study of the seismic, bradyseismic and eruptive activity of the Campi Flegrei caldera. The aim is to make a revised historical data available for accurate volcanological interpretation, supplying additional data and highlighting spurious previous data. The analysis begins with the supposed 1198 eruption, which did not actually take place. No information is available for the thirteenth and fourteenth centuries. As far as the fifteenth and sixteenth centuries are concerned, only direct sources were examined for this paper, and they include many different types of evidence. The chronological breadth of the analysis has also provided information about the seismic crises and bradyseisms prior to the eruption of 1538. The exceptional nature of this 1538 eruption attracted the attention of intellectuals, diplomats and natural philosophers, who left valuable accounts, which we have analysed, and which include many that are still available in their original manuscript form. The previous studies concerning the 1538 eruption were based on 23 (variously used) sources. We have examined 35 additional sources bringing the overall corpus of sources analysed to 58. The results provide a more precise scenario of events preceding the 1538 eruption, including bradyseismic activity starting from the end of the fifteenth century. The chronology of the phenomena described comprises the core result of this study, and has been constructed so as to clarify the time, location and impact of each event. For the 1538 eruption, a countdown is included which may also have a predictive value. For the last 36?| hours before eruption began, the countdown is hour-by-hour. The effects of the eruption and earthquakes on people, structures and society are also described for Pozzuoli, Agnano and Naples. The areas where heavy materials and ash fell are likewise indicated, as well are the earth tremors felt by the population from the eruptive

  18. Eruption source processes derived from seismic and acoustic observations of the 25 September 2007 Ruapehu eruption—North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Jolly, A. D.; Sherburn, S.; Jousset, P.; Kilgour, G.

    2010-03-01

    Mt. Ruapehu erupted on 25 September 2007 at 20:26 PM NZDT (8:26 UT) generating a steam column to about 15,000 ft (4600 m), a directed ballistic and surge deposit of coarse blocks and ash to the north of the Crater Lake, and initiated lahars in the Whangaehu catchment and Whakapapa ski field. The eruption was recorded on three broadband seismometers and two acoustic pressure sensors which indicated broadly coherent waveform characteristics across the network. The eruption had a duration of less than 1 min as indicated by strong seismic and acoustic pulses. The acoustic wave coincided with observed very long-period (VLP) seismic signal (2-25 s period). The acoustic pulse had a positive pressure (indicating an explosion) and travelled at a velocity of ˜ 320 m/s. The syn-eruptive VLP was composed of surface waves having strong radial and transverse components. The immediate aftermath of the eruption produced about 4 min of continued high amplitude spasmodic tremor signals that probably resulted from post-explosion phase associated vent backfill/stabilisation. The eruption was preceded by minor volcano-tectonic earthquakes and tremor bursts which began 10 min before the main eruption. Two smaller VLP signals were associated with these tremor pulses at 20:17 and 20:25. These pre-eruptive VLP signals had particle motions indicating body and surface waves from a sub-surface source region. Modelling of the VLP sources using a 3D finite-difference method shows that that the pre-eruption VLP signals are consistent with a volume fluctuation at 3-7 km depth from a radially symmetric source. The main eruption VLP was consistent with a south and downward directed single force in response to a northward directed jet and northward directed ballistic deposits.

  19. 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.

  20. Eruptive History of Arenal Volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Soto, G. J.; Alvarado, G. E.

    2004-12-01

    Tephra-stratigraphy, volcanic history, eruption types, eruptive dynamics and area distribution of tephra from the most important eruptions of Arenal volcano, are reviewed and updated. Deposits of explosive eruptions are named AR-1 to AR-22 (from older to younger). All previous and new Arenal and neighbouring Chato volcanoes' radiocarbon dates were calibrated: the last Chato eruption occurred 3720±150 B.P and the first known eruption of Arenal (AR-1), 7010+170-130 B.P. Isopachs and characteristics of the most relevant and recognized airfall deposits are presented. Area distributions of the key layers are oriented toward W, WSW and SW, except the lowest layer of AR-17, which is distributed northward. According to lithic isopleths, an eruption column height of 23 km (subplinian) was calculated for AR-20. Most fall layers in Arenal show associated pyroclastic flow deposits up to a distance of 6.5 km from the summit. They are restricted to river valley paths. Among Arenal eruptions, plinian-subplinian type events like AR-20, AR-15, AR-12 and AR-9, are the most violent and destructive, with tephra volumes between 0.2 and 1 km3. There are also violent strombolian eruptions which were sustained for a considerable time, resembling subplinian eruptions (the AR-19 case, total volume 0.45 km3), and pelean type eruptions, as AR-22, which erupted 0.026 km3 of tephra. A temporal correlation of explosive events after AR-8 shows that the four most important dacitic eruptions (AR-20, 15, 12 and 9), are separated by an average period of 800 years ("long term"). Three of them (AR-20, 15 and 9) have been preceded by two important explosive events with a more basic chemistry, which occurred around 300 years or less previously to the dacitic eruption ("short term" periods). Nevertheless, between cycles AR-13/14/15 and AR-18/19/20, there are two events (AR-16 and 17) that do not belong to any cycle. In fact, between the major eruptions AR-15 and 20, the highest eruptive frequency of all

  1. Observed Aspects of Reconnection in Solar Eruptions

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.

    2010-01-01

    Signatures of reconnection in major CME (coronal mass ejection)/flare eruptions and in coronal X-ray jets are illustrated and interpreted. The signatures are magnetic field lines and their feet that brighten in flare emission. CME/flare eruptions are magnetic explosions in which: 1. The field that erupts is initially a closed arcade. 2. At eruption onset, most of the free magnetic energy to be released is not stored in field bracketing a current sheet, but in sheared field in the core of the arcade. 3. The sheared core field erupts by a process that from its start or soon after involves fast tether-cutting reconnection at an initially small current sheet low in the sheared core field. If the arcade has oppositely-directed field over it, the eruption process from its start or soon after also involves fast breakout reconnection at an initially small current sheet between the arcade and the overarching field. These aspects are shown by the small area of the bright field lines and foot-point flare ribbons in the onset of the eruption. 4. At either small current sheet, the fast reconnection progressively unleashes the erupting core field to erupt with progressively greater force. In turn, the erupting core field drives the current sheet to become progressively larger and to undergo progressively greater fast reconnection in the explosive phase of the eruption, and the flare arcade and ribbons grow to become comparable to the pre-eruption arcade in lateral extent. In coronal X-ray jets: 1. The magnetic energy released in the jet is built up by the emergence of a magnetic arcade into surrounding unipolar "open" field. 2. A simple jet is produced when a burst of reconnection occurs at the current sheet between the arcade and the open field. This produces a bright reconnection jet and a bright reconnection arcade that are both much smaller in diameter that the driving arcade. 3. A more complex jet is produced when the arcade has a sheared core field and undergoes an

  2. Modeling Eruptive Coronal Magnetohydrodynamic Systems with FLUX

    NASA Astrophysics Data System (ADS)

    Rachmeler, Laurel

    2010-05-01

    I explore solar coronal energetic eruptions in the context of magnetic reconnection, which is commonly thought to be a required trigger mechanism for solar eruptions. Reconnection is difficult to observe in the corona, and current numerical methods cannot model reconnectionless control cases. Thus, it is not possible to determine if it is a necessary component. I have executed multiple controlled simulations to determine the importance of reconnection for initiation and evolution of several eruptive systems using FLUX, a numerical model that uses the comparatively new fluxon technique. I describe two types of eruptions modeled with FLUX: a confined flux rope theory for CME initiation, and symmetrically twisted coronal jets in a uniform vertical background field. In the former, I identified an ideal MHD instability that allows metastable twisted flux rope systems to suddenly lose stability and erupt even in the absence of reconnection, contradicting previous conjecture. The CME result is in contrast to the azimuthally symmetric coronal jet initiation model, where jet-like behavior does not manifest without reconnection. I demonstrate that some eruptive phenomena may be triggered by non-reconnective means such as ideal MHD instabilities, and that magnetic reconnection is not a required element in all coronal eruptions.

  3. 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.

  4. Forecasting volcanic eruptions: the narrow margin between eruption and intrusion

    NASA Astrophysics Data System (ADS)

    Steele, Alexander; Kilburn, Christopher; Wall, Richard; Charlton, Danielle

    2016-04-01

    Volcano-tectonic (VT) seismicity is one of the primary geophysical signals for monitoring volcanic unrest. It measures the brittle response of the crust to changes in stress and provides a natural proxy for gauging the stability of a pressurizing body of magma. Here we apply a new model of crustal extension to observations from the 2015 unrest of Cotopaxi, in Ecuador. The model agrees well with field data and is consistent with accelerating unrest during the pressurization and rupture of a vertically-extended magma source within the volcanic edifice. At andesitic-dacitic stratovolcanoes in subduction zones, unrest after long repose is often characterised by increases in VT event rate that change from an exponential to hyperbolic trend with time. This sequence was observed when renewed unrest was detected in April 2015 at Cotopaxi, following at least 73 years of repose. After about 80 days of elevated seismicity at an approximately steady rate, the numbers of VT events increased exponentially with time for c. 80 days, before increasing for c. 15 days along a faster, hyperbolic trend. Both trends were characterised by the same value of 2 for the ratio of maximum applied stress SF to tensile strength of the crust σT, consistent with the pressurization of an approximately vertical, cylindrical magma body. The hyperbolic trend indicated a potential rupture on 25 September. Rupture appears to have occurred on 21-22 September, when the VT rate rapidly decreased. However, no major eruption accompanied the change, suggesting that a near-surface intrusion occurred instead. Although the quantitative VT trends were consistent with the rupture of a magmatic body, they could not on their own distinguish between an eruptive or intrusive outcome. An outstanding goal remains to identify additional precursory characteristics for quantifying the probability that magma will reach the surface after escaping from a ruptured parent body. Data for this analysis were kindly made available

  5. An interdisciplinary effort to identify source parameters for models that predict eruption cloud transport and dispersion for aviation safety

    NASA Astrophysics Data System (ADS)

    Mastin, L. G.; Guffanti, M.; Servranckx, R.

    2007-12-01

    During recent decades, dozens of commercial and military jets have inadvertently flown through volcanic ash clouds downwind from eruptions. These encounters have caused up to tens of millions of dollars (U.S.) in damage to each jet; a few nearly crashed when ceramitized deposits of ingested ash caused engines to fail. In order to avoid such encounters, the International Civil Aviation Organization (ICAO) has established Volcano Ash Advisory Centers (VAACs) throughout the world to detect eruptions using satellite imagery and to notify aircraft. VAACs also predict the paths of ash clouds using atmospheric transport models, using information on volcanic plume height, the mass rate of tephra entering the atmosphere, the vertical distribution of tephra, eruption duration, and grain size distribution as input parameters. In some cases, these "source parameters" must be estimated during an ongoing eruption with few or no observational constraints. In other cases, satellite or ground-based observations obtained during an eruption constrain plume height, umbrella cloud dimensions or growth rate, and other properties, allowing VAACs to refine source parameters, re-run models, and improve predictions. ICAOs International Airways Volcano Watch Operations Group has recommended improving methods of estimating eruption source parameters as a key step towards improving predictions of volcanic ash transport and dispersion. In the spring of 2007, members of the USGS; NOAA; the Universities of Michigan, Alaska, Pisa, and South Florida; the Air Force Weather Agency; the Australian Bureau of Meteorology; and the Canadian Meteorological Centre began an interagency effort to establish constraints on eruption source parameters. This effort has involved (1) assigning default parameters to volcanoes based on magma and eruption type; (2) improving characterization of total grain-size distribution and the size distribution in distal ash clouds; (3) refining empirical and model

  6. Volumes and eruption rates for the 2008-2009 Chaitén rhyolite lava dome

    NASA Astrophysics Data System (ADS)

    Pallister, J. S.; Diefenbach, A. K.; Griswold, J.; Muñoz, J.; Lara, L. E.; Valenzuela, C.; Burton, W. C.; Keeler, R.

    2010-12-01

    The 2008 eruption of Chaitén caldera, southern Chile, was one of the most explosive on Earth in the past two decades. The eruption began early on 2 May 2008 (UTC) and produced sub-plinian to plinian ash columns between 2 May and 9 May, before transitioning from explosive eruption of tephra to effusive eruption of rhyolite lava. A series of lava flow lobes accumulated within the caldera between late May and the end of the year, burying most of Chaitén’s prehistoric lava dome. A prominent lava spine was also extruded, starting in late 2008. The spine collapsed on 19 February 2009, producing a pyroclastic flow that extended out of the caldera and 7 km down the Río Chaitén. Dome growth continued through 2009, filling in much of the spine-collapse area and further expanding the composite dome through endogenous growth. Dome volumes are computed and eruption rates estimated using satellite data from 2008-10, photogrammetric analysis of oblique aerial photographs taken in January 2010, and digital elevation models derived from ASTER, SRTM, LIDAR and topographic maps. The 2008-10 dome has a total volume of approximately 0.8 km3. About 0.5 km3 erupted within the first four months, when extrusion rates were in the range 10-100 m3s-1. Extrusion rates decreased exponentially over the eruptive period. The 2008-10 dome is similar in volume and composition to the prehistoric lava dome, which has a volume of at least 0.5 km3. Together the two domes constitute about 20-40% of the 3.5-7 km3 collapse volume of the prehistoric caldera. The unusually rapid extrusion rates during the first four months are among the highest ever measured for silicic lava. Chaitén’s 2008-10 lava is obsidian and microcrystalline rhyolite with 75.35+/-0.02% SiO2. A large volume of low viscosity crystal-poor magma (about 0.1% phenocrysts) coupled with high extrusion pressures during the extended transition from explosive to effusive eruption style resulted in these exceptionally high extrusion rates.

  7. A satellite chronology of the May June 2003 eruption of Anatahan volcano

    NASA Astrophysics Data System (ADS)

    Wright, Robert; Carn, Simon A.; Flynn, Luke P.

    2005-08-01

    The first recorded eruption of Anatahan began at approximately 17:00 local time on May 10, 2003. Here, we present observations made by a suite of Earth-orbiting satellites of the heat, ash and gas emitted from the volcano before, during and after the eruption. No thermal or sulphur dioxide emissions are apparent in MODIS (Moderate Resolution Imaging Spectroradiometer), AIRS (Atmospheric Infrared Sounder), EP TOMS (Earth Probe Total Ozone Mapping Spectrometer) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) satellite images acquired prior to the eruption. However, within 24 h of eruption onset, the University of Hawaii's near-real-time satellite thermal monitoring system 'MODVOLC' detected the eruption and confirmed Anatahan's eastern caldera as the center of the activity. Although the eruption was initially phreatic, it quickly transitioned into a magmatic phase that culminated in the emplacement of a dacitic lava dome. The onset of the magmatic phase is recorded by MODVOLC as an order of magnitude increase in the heat flux from the volcano after May 16, indicative of fresh lava at the surface, relative to low values (50-90 MW) observed during the initial phreatic phase. MODVOLC detected thermal emission from the volcano on a further 22 occasions during the next 2 weeks, allowing us to quantitatively document temporal variations in thermal output during the eruption. We use MODIS, EP TOMS and AIRS data to document ash and sulphur dioxide emissions from Anatahan covering the period May 10-June 13, 2003. Using daily satellite observations in conjunction with ground-based estimates, we arrive at a total SO 2 discharge of ˜ 0.51 Mt for the ˜ 1 month of activity, of which ˜ 0.11 Mt was emitted during activity on May 10-12. Decreases in measured SO 2 flux prior to the observation of a lava dome on June 4 indicate that the emerging dome may have blocked the upper conduit and inhibited degassing during this period. A new episode of dome growth

  8. Letter: Lichenoid eruption induced by etanercept.

    PubMed

    Barrientos, Nuria; García-Sánchez, Sagrario; Domínguez, José D

    2012-07-15

    Lichenoid drug eruption is an uncommon, but previously reported, side effect of anti-tumor necrosis factor therapy. The majority of these adverse events relate to infliximab. We report a patient who developed a lichenoid eruption on the back of her hands during etanercept therapy. She improved with topical treatment and discontinuation of the drug was not necessary. The physiopathological link between anti-TNF treatment and lichenoid eruptions remains unclear. It is important to realize that a lichenoid reaction pattern may occur during anti-TNF agent treatment.

  9. A model for Plinian eruptions of Vesuvius

    NASA Astrophysics Data System (ADS)

    Sheridan, M. F.; Barberi, F.; Rosi, M.; Santacroce, R.

    1981-01-01

    The term `Plinian' has been widely used1-4 to describe continuous gas-blast eruptions of large magnitude a typical example5, of which is the AD 79 eruption of Vesuvius which destroyed Pompei and the surrounding region. We develop a new model here for the AD 79 event that explains the complete Plinian eruptive episode including pyroclastic fall, pyroclastic flow, base surge, laharic and phreatic activity. This model has widespread implications with regard to volcanic hazard evaluation and geothermal exploration at Vesuvius and other volcanoes with similar patterns of activity, such as Mount St Helens.

  10. Timing signatures of large scale solar eruptions

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  11. Tranexamic Acid-Induced Fixed Drug Eruption

    PubMed Central

    Matsumura, Natsuko; Hanami, Yuka; Yamamoto, Toshiyuki

    2015-01-01

    A 33-year-old male showed multiple pigmented patches on his trunk and extremities after he took tranexamic acid for common cold. He stated that similar eruptions appeared when he was treated with tranexamic acid for influenza 10 months before. Patch test showed positive results at 48 h and 72 h by 1% and 10% tranexamic acid at the lesional skin only. To our knowledge, nine cases of fixed drug eruption induced by tranexamic acid have been reported in Japan. Tranexamic acid is a safe drug and frequently used because of its anti-fibrinolytic and anti-inflammatory effects, but caution of inducing fixed drug eruption should be necessary. PMID:26288438

  12. Tranexamic Acid-Induced Fixed Drug Eruption.

    PubMed

    Matsumura, Natsuko; Hanami, Yuka; Yamamoto, Toshiyuki

    2015-01-01

    A 33-year-old male showed multiple pigmented patches on his trunk and extremities after he took tranexamic acid for common cold. He stated that similar eruptions appeared when he was treated with tranexamic acid for influenza 10 months before. Patch test showed positive results at 48 h and 72 h by 1% and 10% tranexamic acid at the lesional skin only. To our knowledge, nine cases of fixed drug eruption induced by tranexamic acid have been reported in Japan. Tranexamic acid is a safe drug and frequently used because of its anti-fibrinolytic and anti-inflammatory effects, but caution of inducing fixed drug eruption should be necessary.

  13. Analysis of a Limb Eruptive Event

    NASA Astrophysics Data System (ADS)

    Kotrč, P. Kupryakov, Yu. A.; Bárta, M.; Kashapova, K., L.; Liu, W.

    2016-04-01

    We present the analysis of an eruptive event that took place on the eastern limb on April 21, 2015, which was observed by the Ondřejov horizontal telescope and spectrograph. The eruption of the highly twisted prominence was followed by the onset of soft X-ray sources. We identified the structures observed in Hα spectra with the details on the Hα filtergrams and analyzed the evolution of Doppler component velocities. The timing and observed characteristics of the eruption were compared with the prediction of the model based on the twisting of the flux ropes and the kink/torus instability.

  14. Magmatic volatiles in explosive rhyolitic eruptions

    SciTech Connect

    Eichelberger, J.C.; Westrich, H.R.

    1981-07-01

    Obsidian clasts in rhyolitic tephra deposits preserve preeruption magmatic volatile contents, providing a direct means for determining the volatile content of explosively erupted magmas. Small to moderate volume Plinian eruptions (10/sup -3/ to 10/sup -1/ km/sup 3/) appear to be driven by 0.5--1.0 wt.% volatiles, consisting dominantly of H/sub 2/O with minor CO/sub 2/. Analysis of obsidian from eruptive sequences consisting of tephra and flows indicates that this hydrous magma abruptly overlies magma with only 0.1--0.2 wt.% H/sub 2/O.

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

    NASA Astrophysics Data System (ADS)

    Kurokawa, Aika; Takeo, Minoru; Kurita, Kei

    2016-04-01

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

  16. A Toba-scale eruption in the Early Miocene: The Semilir eruption, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Smyth, Helen R.; Crowley, Quentin G.; Hall, Robert; Kinny, Peter D.; Hamilton, P. Joseph; Schmidt, Daniela N.

    2011-10-01

    The Indonesian archipelago is well-known for volcanic activity and has been the location of three catastrophic eruptions in the last million years: Krakatau, Tambora and Toba. However, there are no reports of large magnitude eruptions during the earlier Cenozoic despite a long volcanic record in Indonesia during subduction of Indian Ocean lithosphere since the Eocene. Here we report an Early Miocene major eruption, the Semilir eruption, in south Java, the main phase of which occurred at 20.7 ± 0.02 Ma. This major volcanic eruption appears similar in scale, but not in type, to the 74 ka Toba event. Its products can be identified elsewhere in Java and are likely to have been distributed widely in SE Asia and adjacent oceans. The Semilir eruption could have triggered a climate response, but cannot yet be linked with certainty to Early Miocene climatic events such as glaciations.

  17. 10,000 Years of explosive eruptions of Merapi Volcano, Central Java: archaeological and modern implications

    USGS Publications Warehouse

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

    2000-01-01

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

  18. 10,000 Years of explosive eruptions of Merapi Volcano, Central Java: archaeological and modern implications

    NASA Astrophysics Data System (ADS)

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

    2000-07-01

    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 <1130±50 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

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

    PubMed

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

    2010-04-13

    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 CO(2). 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 CO(2) 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.

  20. 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.

  1. Infrared Imaging of Strombolian Eruptions

    NASA Astrophysics Data System (ADS)

    Dehn, J.; Harris, A. J.; Ripepe, M.

    2001-12-01

    A forward looking infrared radiometer (FLIR) was used experimentally to capture time series imagery of strombolian eruptions during May and June of 2001 at Stromboli and Etna volcanoes. Though an image is captured only every second or two, eruption sequences covering over 13 hours of imagery over 2 weeks were acquired. Four distinct types of bursts were captured. The first 3 types were observed at Stromboli, and a fourth unique signature was observed at SE crater on Mount Etna. At Stromboli, the three types are; 1) Spatter followed by gas emissions, 2) Gas emissions followed by spatter bursts, and 3) Simultaneous ejections of gas and spatter. Each shows a unique morphology in the time series imagery. The spatter bursts have varying amounts of gas which follow, the gas being much cooler (on the order of 100 degrees Cor more) than the spatter. The volumes of gas estimated using the 2D imagery vary widely, as yet no pattern to this behavior has been discovered. The spatter is not always a single burst, several small sustained (on the order of several seconds) spatter events were observed. The primarily gas bursts showed higher gas volumes and higher gas temperatures than the primarily spatter ejections. Spatter usually, but not always, follows these emissions, and is less voluminous than in the previous ejection type. In the third type, both spatter and gas are ejected simultaneously, the gas emission usually lasting longer than the spatter event. Determination of relative temperatures of the two components is problematic since they overlay one another in the imagery. No relative temperature determinations are made as yet to ejection temperature of spatter in these types due to the relatively small size of the lava bombs in relation to the pixel size in the imagery. However, temperatures over 700 degrees C have been recovered. At Etna a fourth type of burst, mostly gas with a mushroom-shaped structure, followed by a few high ejection angle bombs was observed. These

  2. Active Volcanic Eruptions on Io

    NASA Technical Reports Server (NTRS)

    1996-01-01

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

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

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

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

  3. The 2008 Eruption of Chaitén Volcano, Chile and National Volcano-Monitoring Programs in the U.S. and Chile

    NASA Astrophysics Data System (ADS)

    Ewert, J. W.; Lara, L. E.; Moreno, H.

    2008-12-01

    Chaitén volcano, southern Chile, began erupting on 2 May 2008. The eruption produced 3 Plinian eruption pulses between May 2 and 8. Between Plinian phases the volcano emitted a constant column of ash to approximately 10 km, gradually diminishing to approximately 3 km by the end of June. The eruption of Chaitén was remarkable on several counts--it was the first rhyolite eruption on the planet since Novarupta (Katmai) erupted in 1912, and Chaitén had apparently lain dormant for approximately 9300 years. Though Chaitén is located in a generally sparsely populated region, the eruption had widespread impacts. More than 5000 people had to be quickly evacuated from proximal areas and aviation in southern South America was disrupted for weeks. Within 10 days secondary lahars had overrun much of the town of Chaitén complicating the prospects of the townspeople to return to their homes. Prior to the eruption onset, the nearest real-time seismic station was 300 km distant, and earthquakes were not felt by local citizens until approximately 30 hours before the eruption onset. No other signs of unrest were noted. Owing to the lack of near-field monitoring, and the nighttime eruption onset, there was initial confusion about which volcano was erupting: Chaitén or nearby Michinmahuida. Lack of monitoring systems at Chaitén meant that warning time for the public at risk was extremely short, and owing to the nature of the eruption and the physical geography of the area, it was very difficult to install monitoring instruments to track its progress after the eruption started. The lack of geophysical monitoring also means that an important data set on precursory behavior for silicic systems was not collected. With more than 120 Pleistocene to Holocene-age volcanoes within its continental territory, Chile is one of the more volcanically active countries in the world. The eruption of Chaitén has catalyzed the creation of a new program within the Servicio Nacional de Geología y

  4. C3-class Solar Flare Eruption

    NASA Video Gallery

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

  5. Ring-shaped Prominence Erupts from Sun

    NASA Video Gallery

    A coronal mass ejection (CME) on Jan. 31, 2013 was accompanied by a large prominence eruption best visible in light with a wavelength of 304 angstroms. NASA’s Solar Dynamics Observatory captured ...

  6. Lower third molar eruption following orthodontic treatment.

    PubMed

    Salehi, P; Danaie, S Momene

    2008-01-01

    This study assessed the effect of extraction and preservation of the 1st premolar on lower 3rd molar eruption. Orthodontic clinic records from 1993 to 1995 were evaluated before and after treatment and 8-9 years after treatment for 3 groups of patients: 32 with extraction of 1st premolars in both jaws, 32 with no extraction but orthodontic treatment and 48 controls with no extraction but orthodontic treatment in the upper jaws only. Successful eruption of 3rd molars was evaluated. There was a significant difference in the rates of successful eruptions in the extraction (42%), non-extraction (12%) and control (20%) groups. The findings indicate that 1st premolar extraction may increase the chance of 3rd molar eruption, leading to a lower incidence of health and economic complications.

  7. 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

  8. 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.

  9. Winter warming from large volcanic eruptions

    SciTech Connect

    Robock, A.; Jianping Mao )

    1992-12-24

    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% 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. 21 refs., 2 figs., 1 tab.

  10. Differential Diagnosis of Linear Eruptions in Children.

    PubMed

    Kruse, Lacey L

    2015-08-01

    A 3-year-old girl presented with a linear eruption on her leg for 2 months. She was otherwise healthy and well-appearing. Physical examination showed many small, erythematous, flat-topped papules coalescing into a linear erythematous plaque. At a follow-up visit 9 months later, the eruption had resolved, leaving postinflammatory hypopigmentation.When approaching a cutaneous eruption, appreciating the pattern of the lesions can be instrumental to arriving at the correct diagnosis. For this patient with the acute onset of a plaque on the leg, the differential diagnosis is narrowed by the linear distribution of the skin lesions. The differential diagnosis of linear eruptions in children includes lichen striatus, linear lichen planus, linear psoriasis, inflammatory linear verrucous epidermal nevus, incontinentia pigmenti, phytophotodermatitis, and allergic contact dermatitis. Of note, many of these conditions manifest in a linear manner as a result of cutaneous mosaicism, whereas others are caused by external agents contacting the skin.

  11. STEREO's View of Aug. 24, 2014 Eruption

    NASA Video Gallery

    A bright eruption of solar material surges into space as captured by NASA's Solar Terrestrial Relations Observatory - Before satellite, which currently has a view of the far side of the sun. The in...

  12. Fluconazole-induced Fixed Drug Eruption.

    PubMed

    Gaiser, Cory Allen; Sabatino, Dominick

    2013-03-01

    Triazole antifungals are commonly used in the treatment of oral, esophageal, and vaginal candidiasis. Fluconazole is frequently prescribed as the therapy modality for vaginal fungal infections. On rare occasions, fluconazole has been shown to cause fixed drug eruptions. Lesions of fixed drug eruptions vary in size and number, but have the same general appearance and symptoms. The authors report a case of fluconazole-induced fixed drug eruption in a 24-year-old woman with recurrent vaginal candidiasis. The lesion was initially diagnosed as a spider bite. Topical and oral provocation tests with fluconazole were performed. Topical provocation with petroleum/fluconazole and dimethyl sulfoxide/fluonazole were both negative. Oral provocation was positive, thus confirming the diagnosis of fluconazole-induced fixed drug eruption.

  13. 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

  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. Italian super-eruption larger than thought

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-07-01

    Recent research suggested that the super-eruption of the Campi Flegrei caldera volcano in southern Italy about 40,000 years ago may have played a part in wiping out, or forcing the migration of, the Neanderthal and modern human populations in the eastern Mediterranean regions that were covered in ash. Now a new modeling study by Costa et al. suggests that this eruption may have been even larger than previously thought. This Campi Flegrei eruption produced a widespread ash layer known as Campanian Ignimbrite (CI). Using ash thickness measurements collected at 115 sites and a three-dimensional ash dispersal model, the researchers found that the CI super-eruption would have spread 250-300 cubic kilometers of ash across a 3.7-million-square kilometer region—2 to 3 times previous ash volume estimates.

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

  17. It is not a fixed drug eruption, it is a fixed "sunlight" eruption.

    PubMed

    Valdivieso, Rommel; Cañarte, Cecilia

    2010-12-01

    Hyperpigmented fixed eruption is a phenomenon usually related with drug antigens, and known as fixed drug eruption. A woman had a skin condition with clinical and histopathologic indications of fixed drug eruption. The disease first appeared when she went to a swimming pool and left with hyperpigmented macules. Previously affected skin reactivated on three other occasions when she again visited swimming pools. Sunlight involvement (UVA-UVB) was demonstrated through phototests. Sunlight should be considered as a cause of fixed drug-like eruption and a possible cause of some cases of FDE without any apparent etiological factor.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Preventive health measures in volcanic eruptions.

    PubMed Central

    Baxter, P J; Bernstein, R S; Buist, A S

    1986-01-01

    Medical treatment has only a small role in severe volcanic eruptions and so preventive measures are paramount if injuries and loss of life are to be reduced. The health team must be incorporated in emergency planning and response at the earliest stage. Guidance on the interpretation of geological information about a volcano and the appropriate health measures that should be adopted before and after an eruption are summarized for the benefit of health workers. PMID:3946731

  3. Tephra from the 1979 soufriere explosive eruption.

    PubMed

    Sigurdsson, H

    1982-06-04

    The explosive phase of the 1979 Soufriere eruption produced 37.5 x 10(6) cubic meters (dense-rock equivalent) of tephra, consisting of about 40 percent juvenile basaltic andesite and 60 percent of a nonjuvenile component derived from the fragmentation of the 1971-1972 lava island during phreatomagmatic explosions. The unusually fine grain size, poor sorting, and bimodality of the land deposit are attributed to particle aggregation and the formation of accretionary lapilli in a wet eruption column.

  4. Mt. Pinatubo Volcano - Post Eruption, Luzon, Philippines

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Mt. Pinatubo on the island of Luzon (14.5N, 120.5E) erupted catastrophically in June 1991 after over 600 years of inactivity. Partially obscured by clouds in this post eruption photo, the crater is not obvious in this scene but the blowout area, in the once heavily forested region, is easily observed as lava flow, ash fallout, mud slide and debris trails mar the landscape. Clark AFB, once the crossroads of the SW Pacific can only partially be seen.

  5. 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."

  6. Azithromycin induced bullous fixed drug eruption.

    PubMed

    Das, Anupam; Sancheti, Karan; Podder, Indrashis; Das, Nilay Kanti

    2016-01-01

    Fixed drug eruption (FDE) is a common type of drug eruption seen in skin clinics. It is characterized by solitary or multiple, round to oval erythematous patches with dusky red centers, some of which may progress to bulla formation. Bullous FDE may be caused by a number of drugs. We hereby describe a case of azithromycin-induced bullous FDE; to the best of our knowledge, this is the first such case being reported.

  7. Generalized pustular eruptions due to terbinafine.

    PubMed

    Ozturk, Gunseli; Turk, Bengu Gerceker; Karaca, Nezih; Karaarslan, Isil Kilinc; Ertekin, Banu; Ertam, Ilgen; Kazandi, Alican; Kandiloglu, Gulsen

    2012-03-01

    Terbinafine, a widely used antifungal agent, may rarely cause cutaneous side effects with an incidence of 2.7%. Generalized pustular eruptions are quite uncommon but severe adverse cutaneous reactions of terbinafine have been reported. The main pustular eruptions due to terbinafine include acute generalized exanthematous pustulosis and drug induced pustular psoriasis. In this report, two cases of acute generalized exanthematous pustulosis and one case of generalized pustular psoriasis triggered with terbinafine are presented.

  8. 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

  9. Climatic impact of volcanic eruptions

    NASA Technical Reports Server (NTRS)

    Rampino, Michael R.

    1991-01-01

    Studies have attempted to 'isolate' the volcanic signal in noisy temperature data. This assumes that it is possible to isolate a distinct volcanic signal in a record that may have a combination of forcings (ENSO, solar variability, random fluctuations, volcanism) that all interact. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on temperatures in regions where the effects of aerosol clouds may be amplified by perturbed atmospheric circulation patterns. This is especially true in subpolar and midlatitude areas affected by changes in the position of the polar front. Such climatic perturbation can be detected in proxy evidence such as decrease in tree-ring widths and frost rings, changes in the treeline, weather anomalies, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures. In low latitudes, sudden temperature drops were correlated with the passage overhead of the volcanic dust cloud (Stothers, 1984). For some eruptions, such as Tambora, 1815, these kinds of proxy and anectdotal information were summarized in great detail in a number of papers and books (e.g., Post, 1978; Stothers, 1984; Stommel and Stommel, 1986; C. R. Harrington, in press). These studies lead to the general conclusion that regional effects on climate, sometimes quite severe, may be the major impact of large historical volcanic aerosol clouds.

  10. Volcanic eruptions; energy and size

    USGS Publications Warehouse

    de la Cruz-Reyna, S.

    1991-01-01

    The Earth is a dynamic planet. Many different processes are continuously developing, creating a delicate balance between the energy stored and generated in its interior and the heat lost into space. The heat in continuously transferred through complex self-regulating convection mechanisms on a planetary scale. The distribution of terrestrial heat flow reveals some of the fine structure of the energy transport mechanisms in the outer layers of the Earth. Of these mechanisms in the outer layers of the Earth. Of these mechanisms, volcanism is indeed the most remarkable, for it allows energy to be transported in rapid bursts to the surface. In order to maintain the subtle balance of the terrestrial heat machine, one may expect that some law or principle restricts the ways in which these volcanic bursts affect the overall energy transfer of the Earth. For instance, we know that the geothermal flux of the planet amounts to 1028 erg/year. On the other hand, a single large event like the Lava Creek Tuff eruption that formed Yellowstone caldera over half a million years ago may release the same amount of energy in a very small area, over a short period of time. 

  11. Identifying recycled ash in basaltic eruptions

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  12. Excitation of atmospheric oscillations by volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Kanamori, Hiroo; Mori, Jim; Harkrider, David G.

    1994-11-01

    We investigated the mechanism of atmospheric oscillations with periods of about 300 s which were observed for the 1991 Pinatubo and the 1982 El Chichon eruptions. Two distinct spectral peaks, at T = 270 and 230 s for the Pinatubo eruption and at T = 195 and 266 s for the El Chichon eruptions, have been reported. We found similar oscillations for the 1980 Mount St. Helens and the 1883 Krakatoa eruptions. To explain these observations, we investigated excitation problems for two types of idealized sources, 'mass injection' and 'energy injection' sources, placed in an isothermal atmosphere. In general, two modes of oscillations, 'acoustic' and 'gravity' modes, can be excited. For realistic atmospheric parameters, the acoustic and gravity modes have a period of 275 and 304 s, respectively. For a realistic time history of eruption, atmospheric oscillations with an amplitude of 50 to 100 Pa (0.5 to 1 mbar) can be excited by an energy injection source with a total energy of 10(exp 17) J. This result is consistent with the observations and provides a physical basis for interpretation of atmospheric oscillations excited by volcanic eruptions.

  13. Effects of Vent Asymmetry on Explosive Eruptions

    NASA Astrophysics Data System (ADS)

    Sim, S.; Ogden, D. E.

    2012-12-01

    Current computer models of volcanic eruptions are typically based on symmetric vent and conduit geometries. However, in natural settings, these features are rarely perfectly symmetric. For example, the May 18, 1980 eruption of Mount St Helens (MSH) took place through a highly asymmetrical crater due to the preceding landslide and subsequent vent erosion. In supersonic, high pressure eruptions, such as what may have occurred at MSH, vent and crater asymmetry can strongly affect the directionality of the gas-thrust region. These effects on eruption direction may have implications for the formation of lateral blasts and pyroclastic density currents (PDCs). Here, we present preliminary results from numerical simulations using CartaBlanca, a Java based simulation tool for non-linear physics as developed at Los Alamos National Laboratory. Using 2D time-dependent simulations of explosive volcanic eruptions, we study the effects of vent asymmetry on a variety of eruptive conditions. Preliminary results suggest that asymmetric vent shape may provide an additional mechanism for the formation of lateral blasts and PDCs.

  14. Mafic Plinian eruptions: Is fast ascent required?

    NASA Astrophysics Data System (ADS)

    Szramek, Lindsay Ann

    2016-10-01

    It has been hypothesized that for a Plinian eruption of mafic magma to occur, that magma must ascend rapidly from the chamber to cause it to fragment into a jet containing juvenile and nonjuvenile tephra. To determine how fast mafic Plinian magmas need to travel to the level of fragmentation, a number of decompression experiments were carried out on two hydrous mafic magmas, and the results are compared to the products of two well-documented mafic Plinian eruptions: the basaltic andesite Fontana eruption of Masaya (Nicaragua) and the hawaiite 122 B.C. eruption of Etna (Italy). Comparison of natural and experimental textures shows that the Fontana eruption can be replicated in the lab at decompression rates between 0.1 MPa s-1 and 0.2 MPa s-1. This decompression rate is faster than any previously determined experimentally rate for more silicic eruptions. The hawaiite was unable to be reproduced in the lab. The natural groundmass is highly crystalline, which would have raised the viscosity of the initial melt by 1-2 orders of magnitude, which may not be enough to cause fragmentation.

  15. Identifying recycled ash in basaltic eruptions.

    PubMed

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

    2014-07-28

    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.

  16. 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

  17. Impulsive Seafloor Signals from the 2015 Eruption of Axial Seamount

    NASA Astrophysics Data System (ADS)

    Garcia, C.; Wilcock, W. S. D.; Tan, Y. J.; Tolstoy, M.

    2015-12-01

    Axial Seamount is a hotspot volcano on the Juan de Fuca Ridge that has erupted three times over the past two decades. The most recent eruption was recorded by a cabled seismic network in the southern half of the summit caldera that has been operated by the Ocean Observatories Initiative (OOI) since November 2014. After five months of increasing seismicity, a 10-hour seismic crisis involving thousands of earthquakes began at 0500 GMT on April 24, 2015 accompanied by ~2 m of deflation in the central caldera (Nooner et al., this meeting). Local seismicity declined rapidly after the eruption, but thousands of impulsive waterborne events were observed across the network starting immediately after the seismic crisis. Over 1500 events per day were recorded on April 25 and 26, decreasing to less than 500 per day after May 1, and ceasing altogether around May 20. Each event comprises a train of three to five consistently spaced arrivals visible on all 3 seismometer channels with a broad frequency content of 10-100 Hz. The timing of arrivals across the network is consistent with water column multiples from a seafloor source to the north. A subset of events has been manually picked and located by modeling travel times of the first three arrivals assuming flat bathymetry at a range of depths between 1500-1800 m and a sound speed of 1.5 km/s. The preliminary locations are clustered around Axial Seamount's northern rift at a distance of 10-15 km from the north rim of the caldera. In July, an OOI cruise discovered fresh pillow lavas up to 100 m thick and 670 m wide, and extending for 7 km along the rift in the same region (Kelley et al., this meeting). The source of the impulsive events is uncertain and could involve gas explosions, bubble collapse, and thermal or mechanical cracking, but their colocation with the fresh lava flow suggests that ocean bottom seismic networks can not only track the faulting and fracturing associated with subsurface magma movements but also the

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  19. New insights into the initiation and venting of the Bronze-Age eruption of Santorini (Greece), from component analysis

    NASA Astrophysics Data System (ADS)

    Druitt, T. H.

    2014-02-01

    The late-seventeenth century BC Minoan eruption of Santorini discharged 30-60 km3 of magma, and caldera collapse deepened and widened the existing 22 ka caldera. A study of juvenile, cognate, and accidental components in the eruption products provides new constraints on vent development during the five eruptive phases, and on the processes that initiated the eruption. The eruption began with subplinian (phase 0) and plinian (phase 1) phases from a vent on a NE-SW fault line that bisects the volcanic field. During phase 1, the magma fragmentation level dropped from the surface to the level of subvolcanic basement and magmatic intrusions. The fragmentation level shallowed again, and the vent migrated northwards (during phase 2) into the flooded 22 ka caldera. The eruption then became strongly phreatomagmatic and discharged low-temperature ignimbrite containing abundant fragments of post-22 ka, pre-Minoan intracaldera lavas (phase 3). Phase 4 discharged hot, fluidized pyroclastic flows from subaerial vents and constructed three main ignimbrite fans (northwestern, eastern, and southern) around the volcano. The first phase-4 flows were discharged from a vent, or vents, in the northern half of the volcanic field, and laid down lithic-block-rich ignimbrite and lag breccias across much of the NW fan. About a tenth of the lithic debris in these flows was subvolcanic basement. New subaerial vents then opened up, probably across much of the volcanic field, and finer-grained ignimbrite was discharged to form the E and S fans. If major caldera collapse took place during the eruption, it probably occurred during phase 4. Three juvenile components were discharged during the eruption—a volumetrically dominant rhyodacitic pumice and two andesitic components: microphenocryst-rich andesitic pumices and quenched andesitic enclaves. The microphenocryst-rich pumices form a textural, mineralogical, chemical, and thermal continuum with co-erupted hornblende diorite nodules, and together

  20. 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

  1. Seismic recording of the Anatahan eruption

    NASA Astrophysics Data System (ADS)

    Pozgay, S. H.; Wiens, D. A.; Shore, P. J.; Sauter, A.; Camacho, J. T.

    2003-12-01

    The first historic eruption of Anatahan volcano was fortuitously recorded by a broadband PASSCAL seismograph installed on the island only 4 days prior to the eruption. Although covered by ash during the eruption, the seismograph continued to operate throughout the main two month period of activity on Anatahan. This seismograph, located about 6 km west of the active eastern crater, as well as a seismograph installed on Sarigan about 45 km to the north, provide a continuous record of activity during the eruption. We have manually analyzed and visually picked arrivals from the 14 day period beginning 4 days prior to the eruption, and we have implemented an automatic event identification algorithm for the rest of the eruption period that has been calibrated relative to the manually processed data. In addition, we have located many of the larger volcano tectonic (VT) earthquakes using the P and S wave arrivals at Anatahan and Sarigan as well as P wave polarization data. Although these locations are not highly accurate they serve to delineate the general spatial progression of the earthquake activity. No earthquakes occurred in the crater region during the 4 days prior to the eruption. The only significant precursory earthquake activity was a swarm of events on May 8 that were located about 15 km northeast of the island and significantly deeper than events directly associated with the eruption. The first VT event from Anatahan itself was recorded at about 02:00 hrs GMT on May 10. The number of events per hour increases dramatically between 02:00 and 07:00 GMT. A period of nearly continuous earthquake activity commences at about 06:20 GMT which corresponds well with the eruption time of 07:30 GMT estimated by the Volcanic Ash Advisory Center from satellite photos of the ash cloud. After about 36 hours of intense earthquake activity, the number of discrete earthquakes declined, and were replaced by nearly continuous volcanic tremor. Much of the later part of the eruption

  2. Volcano Monitoring and Eruption Response in Japan

    NASA Astrophysics Data System (ADS)

    Nakada, S.; Morita, Y.

    2010-12-01

    Although the start of eruption was forecasted at Miyakejima in June 2000, its change since then was largely different from what we expected; the countermeasures always became one step behind. There was a sudden lateral intrusion of the enormous amount magma as far as 30 km away from the volcano. The failure in forecasting comes partly from insufficient consideration of the eruption history and simple analogy of recent, near-steady state eruption events. The 2000 eruption may be reappearance of that of 2.5 ka at Miyakejima. The national project of eruption prediction researches has focused on seismological and geomagnetic investigations to detect the temporal change in the subsurface structure for active volcanoes, together with repeated, multidiscipline intensive observation. These were considered important to understand magma storage and movement, to evaluate the eruption potential, and to forecast the future eruption. Although direct detection of the magma chamber was incomplete, the convex distribution of dense material beneath the summit became common throughout examined volcanoes. It became clear that the part consists of the dike swarms through the conduit drilling project at Unzen. Understanding of the velocity structure by the seismic experiments was very useful to determine the detail location of volcano earthquakes in those volcanoes. Furthermore, combination of seismic, geodetic, geomagnetic and petrological investigations provided us a better imaging of the subsurface structure of several volcanoes. New technology such as the cosmic-ray (muon) radiography, which made the volcano interior visible, will give us the important information on magma ascent in the shallowest part of volcano. Recently, seismological and geodetic monitoring at densely-located observation sites makes possible to image the magma’s ascent and accumulation under volcanoes from the middle to upper crust. This process, of course, needs knowledge on the subsurface structure (depth of

  3. Volcano shapes, entropies, and eruption probabilities

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust; Mohajeri, Nahid

    2014-05-01

    We propose that the shapes of polygenetic volcanic edifices reflect the shapes of the associated probability distributions of eruptions. In this view, the peak of a given volcanic edifice coincides roughly with the peak of the probability (or frequency) distribution of its eruptions. The broadness and slopes of the edifices vary widely, however. The shapes of volcanic edifices can be approximated by various distributions, either discrete (binning or histogram approximation) or continuous. For a volcano shape (profile) approximated by a normal curve, for example, the broadness would be reflected in its standard deviation (spread). Entropy (S) of a discrete probability distribution is a measure of the absolute uncertainty as to the next outcome/message: in this case, the uncertainty as to time and place of the next eruption. A uniform discrete distribution (all bins of equal height), representing a flat volcanic field or zone, has the largest entropy or uncertainty. For continuous distributions, we use differential entropy, which is a measure of relative uncertainty, or uncertainty change, rather than absolute uncertainty. Volcano shapes can be approximated by various distributions, from which the entropies and thus the uncertainties as regards future eruptions can be calculated. We use the Gibbs-Shannon formula for the discrete entropies and the analogues general formula for the differential entropies and compare their usefulness for assessing the probabilities of eruptions in volcanoes. We relate the entropies to the work done by the volcano during an eruption using the Helmholtz free energy. Many factors other than the frequency of eruptions determine the shape of a volcano. These include erosion, landslides, and the properties of the erupted materials (including their angle of repose). The exact functional relation between the volcano shape and the eruption probability distribution must be explored for individual volcanoes but, once established, can be used to

  4. 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

  5. Apparent Eruptive Response of Cascades and Alaska-Aleutian Arc Volcanoes to Major Deglaciations

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.; Sisson, T. W.; Bacon, C. R.; Ferguson, D. J.

    2014-12-01

    Precise argon ages of Pleistocene eruptive products from Cascades and Alaska-Aleutian arc volcanoes cluster in time following major deglaciations. Compilation of edifice-volume-weighted dates for over 700 lavas from 16 volcanoes are compared to marine oxygen isotope stages (MIS 2-8) of Bassinot et al. (1994, EPSL, v. 126, p. 91-108) and interpreted temperatures from the Vostok ice core (Petit et al., 1999, Nature, v. 399, p. 429-436). To assess relative time-volume relationships we weight the distribution of ages measured at each volcano by its total edifice volume. The abundance of ages scales with the number of mapped eruptive units, and may differ substantially from the true eruptive output. The distribution is also weighted inversely by the number of dates to account for centers with more or fewer dates. Stacked probability density functions yield significant peaks after MIS 6 and MIS 8. Veniaminof, Emmons Lake, Westdahl, Redoubt (Alaska-Aleutian arc), and Adams and Crater Lake (Cascades arc) have apparent eruptive episodes 135-110 ka (early MIS 5), coinciding with rapid warming of the oceans following the MIS 6 glacial. Veniaminof began growing at 250 ka (end MIS 8) and erupted more than 200 km3 of lava in MIS 7. Emmons Lake, Adams, Rainier, and Glacier Peak also have apparent growth peaks (abundant dated units) following MIS 8. Apparent correlation of eruptive episodes with deglaciations may result from depressurization of magmatic systems due to ice retreat resulting in enhanced decompression melting and/or diminished compressive stress on crustal magma reservoirs, poor preservation of lava sequences during glacial maxima, or coincidence. Next steps in this study include (1) more rigorous assessment of eruptive volumes of dated map units, (2) refining ice volume estimates during MIS 2, 6, and 8 at various centers by dating ice marginal lava flows and tuyas and by mapping moraines at selected volcanoes, (3) re-analyzing sequences previously dated by K/Ar to

  6. A FLUX ROPE ERUPTION TRIGGERED BY JETS

    SciTech Connect

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

    2010-03-10

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

  7. Magma chamber dynamics and Vesuvius eruption forecasting

    NASA Astrophysics Data System (ADS)

    Dobran, F.

    2003-04-01

    Magma is continuously or periodically refilling an active volcano and its eruption depends on the mechanical, fluid, thermal, and chemical aspects of the magma storage region and its surroundings. A cyclically loaded and unloaded system can fail from a weakness in the system or its surroundings, and the fluctuating stresses can produce system failures at stress levels that are considerably below the yield strength of the material. Magma in a fractured rock system within a volcano is unstable and propagates toward the surface with the rate depending on the state of the system defined by the inertia, gravity, friction, and permeability parameters of magma and its source region. Cyclic loading and unloading of magma from a reservoir caused by small- or medium-scale eruptions of Vesuvius can produce catastrophic plinian eruptions because of the structural failure of the system and the quiescent periods between these eruptions increase with time until the next eruption cycle which will be plinian or subplinian and will occur with a very high probability this century. Such a system behavior is predicted by a Global Volcanic Simulator of Vesuvius developed for simulating different eruption scenarios for the purpose of urban planning the territory, reducing the number of people residing too close to the cone of the volcano, and providing safety to those beyond about 5 km radius of the crater. The magma chamber model of the simulator employs a thermomechanical model that includes magma inflow and outflow from the chamber, heat and mass transfer between the chamber and its surroundings, and thermoelastoplastic deformation of the shell surrounding the magma source region. These magma chamber, magma ascent, and pyroclastic dispersion models and Vesuvius eruption forecasting are described in Dobran, F., VOLCANIC PROCESSES, Kluwer Academic/Plenum Publishers, 2001, 590 pp.

  8. Characterize Eruptive Processes at Yucca Mountain, Nevada

    SciTech Connect

    G. Valentine

    2001-12-20

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

  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. 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.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  13. 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.

  14. Seismicity of block-and-ash flows occurring during the 2006 eruption of Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    DeRoin, Nicole; McNutt, Stephen R.; Sentman, Davis D.; Reyes, Celso

    2012-02-01

    In January 2006, Augustine Volcano began erupting following an increase in seismicity that was first noted in late April 2005. Thirteen large explosive eruptions of Augustine occurred from January 11 to 28, 2006, followed by a continuously erupting phase and then by a dome growth phase in which numerous pyroclastic flows and block-and-ash flows occurred. As a new steep-sided and unstable dome grew in spring 2006, rockfalls and related events, likely block-and-ash flows, dominated the seismic record. Relative amplitudes at pairs of seismic stations for 68 block-and-ash flow events were examined to constrain locations of the flow-events. Higher amplitudes were associated with events closer to a given station. These relations were confirmed by images collected on a low-light camera. Captured images show a correlation between flow direction and seismic amplitude ratios from nearby stations AUE and AUW. Seismic amplitudes and energies of the flow signals, measured in several different ways, were found to correlate with the surface areas and run-out distances of the flows. The ML range of rockfalls was 0.1 to 1.1, and seismic efficiencies were estimated to be much less than 1%. Particle motion analyses showed that the seismic waves contained both body waves and surface waves and demonstrate that the flows were acting as moving sources with velocities of 30-93 m/s.

  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. 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

  17. Precursors of eruptions at Vesuvius (Italy)

    NASA Astrophysics Data System (ADS)

    Scandone, Roberto; Giacomelli, Lisetta

    2008-04-01

    The historical record of activity of Mount Vesuvius is uncommonly long and may serve as a guide to understand precursors before the outbreak of new activity. Reposes of different lengths have been observed in the past, with long ones preceding violent explosive eruptions. Eruptions occurring during periods of permanent activity have been preceded by possible deformation of the volcanic edifice and by short duration, earthquake swarms. Otherwise they have occurred without any reported precursors. The renewal of activity after long periods, like the current one, has been preceded by unrest lasting years to weeks, as a new eruption would require connection to the surface of a reservoir at depth ranging between 6 and 4 km. Since 1944, episodic seismic swarms, have occurred with a frequency similar to that of the violent strombolian eruptions during the last period of permanent activity; they are interpreted as intrusions and arrest of magma batches into a reservoir at the same depth of that feeding past sub-plinian eruptions.

  18. 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.

  19. An arcade-like eruptive prominence

    NASA Astrophysics Data System (ADS)

    Zhong, Shu-Hua; Zhan, La-Sheng

    2004-12-01

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

  20. 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.

  1. Coronal bright points associated with minifilament eruptions

    SciTech Connect

    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 10{sup 9} cm{sup –3}. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  2. Evolution of Neogene Dynamic Topography in Africa

    NASA Astrophysics Data System (ADS)

    Paul, Jonathan; Roberts, Gareth; White, Nicky

    2013-04-01

    The characteristic basins and swells of Africa's surface topography probably reflect patterns of convective circulation in the sub-lithospheric mantle. We have interrogated drainage networks to determine the spatial and temporal pattern of convectively driven uplift. ~560 longitudinal river profiles were extracted from a digital elevation model of Africa. An inverse model is then used to minimise the misfit between observed and calculated river profiles as a function of uplift rate history. During inversion, the residual misfit decreases from ~22 to ~5. Our results suggest that Africa's topography began to grow most rapidly after ~30 Ma at peak uplift rates of 0.1-0.15 mm/yr. The algorithm resolves distinct phases of uplift which generate localized swells of high topography and relief (e.g. the Angolan Dome). Uplift rate histories are shown to vary significantly from swell to swell. The calculated magnitudes, timing, and location of uplift agree well with local independent geological constraints, such as intense volcanism at Hoggar (42-39 Ma) and Afar (31-29 Ma), uplifted marine terraces, and warped peneplains. We have also calculated solid sediment flux histories for major African deltas which have persisted through time. This onshore record provides an important indirect constraint on the history of vertical motions at the surface, and agrees well with the offshore flux record, obtained from mapping isopachs of deltaic sediments. Our modelling and reconstructed sedimentary flux histories indicate that the evolution of drainage networks may contain useful information about mantle convective processes.

  3. 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

  4. Management of Ectopically Erupting Maxillary Incisors: A Case Series

    PubMed Central

    Suresh, Kotumachagi Sangappa; Uma, HL; Nagarathna, J

    2015-01-01

    ABSTRACT Eruption disturbances related to the position include ectopic eruption and transpositions. The occurrence of ectopic eruption is most commonly associated with maxillary incisors. The normal eruption, position and morphology of these teeth are crucial to craniofacial development, facial esthetics as well as phonetics. It is essential that the clinicians have thorough knowledge of the eruption disturbances in order to make an appropriate, as well as timely intervention, as dictated by the complexity of the problem. How to cite this article: Suresh KS, Uma HL, Nagarathna J, Kumar P. Management of Ectopically Erupting Maxillary Incisors: A Case Series. Int J Clin Pediatr Dent 2015;8(3):227-233. PMID:26604543

  5. Management of Ectopically Erupting Maxillary Incisors: A Case Series.

    PubMed

    Suresh, Kotumachagi Sangappa; Uma, H L; Nagarathna, J; Kumar, Pravin

    2015-01-01

    Eruption disturbances related to the position include ectopic eruption and transpositions. The occurrence of ectopic eruption is most commonly associated with maxillary incisors. The normal eruption, position and morphology of these teeth are crucial to craniofacial development, facial esthetics as well as phonetics. It is essential that the clinicians have thorough knowledge of the eruption disturbances in order to make an appropriate, as well as timely intervention, as dictated by the complexity of the problem. How to cite this article: Suresh KS, Uma HL, Nagarathna J, Kumar P. Management of Ectopically Erupting Maxillary Incisors: A Case Series. Int J Clin Pediatr Dent 2015;8(3):227-233.

  6. Arizona-sized Io Eruption

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These images of Jupiter's volcanic moon, Io, show the results of a dramatic event that occurred on the fiery satellite during a five-month period. The changes, captured by the solid state imaging (CCD) system on NASA's Galileo spacecraft, occurred between the time Galileo acquired the left frame, during its seventh orbit of Jupiter, and the right frame, during its tenth orbit. A new dark spot, 400 kilometers (249 miles) in diameter, which is roughly the size of Arizona, surrounds a volcanic center named Pillan Patera. Galileo imaged a 120 kilometer (75 mile) high plume erupting from this location during its ninth orbit. Pele, which produced the larger plume deposit southwest of Pillan, also appears different than it did during the seventh orbit, perhaps due to interaction between the two large plumes. Pillan's plume deposits appear dark at all wavelengths. This color differs from the very red color associated with Pele, but is similar to the deposits of Babbar Patera, the dark feature southwest of Pele. Some apparent differences between the images are not caused by changes on Io's surface, but rather are due to differences in illumination, emission and phase angles. This is particularly apparent at Babbar Patera.

    North is to the top of the images. The left frame was acquired on April 4th, 1997, while the right frame was taken on Sept. 19th, 1997. The images were obtained at ranges of 563,000 kilometers (350,000 miles) for the left image, and 505,600 kilometers (314,165 miles) for the right.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

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

  7. 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.

  8. 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…

  9. Mafic intrusions triggering eruptions in Iceland

    NASA Astrophysics Data System (ADS)

    Sigmarsson, O.

    2012-04-01

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

  10. Generation 2030/Africa

    ERIC Educational Resources Information Center

    You, Danzhen; Hug, Lucia; Anthony, David

    2014-01-01

    Until relatively recently, much of Africa has been among the economically least developed and least densely populated places on earth, replete with villages and rural communities. Africa is changing rapidly, in its economy, trade and investment; in climate change; in conflict and stability; in urbanization, migration patterns, and most of all in…

  11. Islam in Africa

    DTIC Science & Technology

    2008-05-09

    orders as well as followers in West Africa and Sudan, and, like other orders, strives to know God through meditation and emotion. Sufis may be Sunni or...Shi’ite, and their ceremonies may involve chanting, music, dancing, and meditation . West Africa and Sudan have various Sufi orders regarded

  12. Language in South Africa.

    ERIC Educational Resources Information Center

    Mesthrie, Rajend, Ed.

    This collection of 24 papers focuses on language and society in South Africa. Part 1, "The Main Language Groupings," includes (1) "South Africa: A Sociolinguistic Overview" (R. Mesthrie); (2) "The Khoesan Languages" (A. Traill); (3) "The Bantu Languages: Sociohistorical Perspectives" (Robert K. Herbert and…

  13. Teaching about Francophone Africa.

    ERIC Educational Resources Information Center

    Merryfield, Mary; Timbo, Adama

    Lessons and resources for Social Studies and French courses are included in this document. The major goals of these materials are to help students (1) explore the history and geography of Francophone Africa, (2) examine French influences in contemporary Africa, (3) recognize and appreciate cultural differences and similarities in values and…

  14. Eruption of Alaska volcano breaks historic pattern

    USGS Publications Warehouse

    Larsen, Jessica; Neal, Christina A.; Webley, Peter; Freymueller, Jeff; Haney, Matthew; McNutt, Stephen; Schneider, David; Prejean, Stephanie; Schaefer, Janet; Wessels, Rick L.

    2009-01-01

    In the late morning of 12 July 2008, the Alaska Volcano Observatory (AVO) received an unexpected call from the U.S. Coast Guard, reporting an explosive volcanic eruption in the central Aleutians in the vicinity of Okmok volcano, a relatively young (~2000-year-old) caldera. The Coast Guard had received an emergency call requesting assistance from a family living at a cattle ranch on the flanks of the volcano, who reported loud "thunder," lightning, and noontime darkness due to ashfall. AVO staff immediately confirmed the report by observing a strong eruption signal recorded on the Okmok seismic network and the presence of a large dark ash cloud above Okmok in satellite imagery. Within 5 minutes of the call, AVO declared the volcano at aviation code red, signifying that a highly explosive, ash-rich eruption was under way.

  15. 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

  16. Magnetic Reconnection in a Solar Eruption -Formation of the Flux Tube and its Eruption-

    NASA Astrophysics Data System (ADS)

    Inoue, Satoshi; Büchner, Jörg

    2016-07-01

    A solar eruption is one of a dramatic phenomenon observed in the solar corona. The flux tube, which is a bundle of highly twisted lines, is widely believed as a driver source of the eruption. Although the magnetic reconnection is a key process of the formation of the flux tube as well as the eruptive process, these dynamics are still open to be solved. In order to clarify these dynamics, we first perform a magnetohydrodynamic (MHD) simulation using a force-free field extrapolated from the photospheric magnetic field. Our simulation successfully produced the typical eruptive processes in which the twisted flux tube slowly ascends in the beginning of the eruption; afterwards, it shows the fast ascending. We found that the reconnection is a key process to break the force-free field initially constructed, and highly twisted flux tube formation during the slow rising phase and even after the fast eruption. Next we compare with Büchner + Skala simulations and compressively discuss the play of the reconnection in the solar eruption.

  17. 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.

  18. 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.

  19. Information fusion techniques applied to eruption forecasting

    NASA Astrophysics Data System (ADS)

    Bursik, M.; Rogova, G.; Deming, J.

    2002-12-01

    We are assembling a relational database of information on past eruptions of the Mono-Inyo volcanic chain, eastern California. The most fundamental tables within the database contain information on locations at which pits were dug through the volcanic stratigraphy, or at which data were collected on a dome or lava flow. The locations include both those at which new data were collected as well as those in the literature. Our working hypothesis is that the database will prove useful for unraveling the complex recent volcanic history of the Mono-Inyo chain. The chain consists of an assortment of domes, craters and flows that stretches for 50 km north-south, subparallel to the Sierran range front fault system. Almost all eruptions within the chain probably occurred less than 50,000 years ago. Because of the variety of magma and eruption types, and the migration of source regions in time and space, it is nontrivial to discern patterns of behaviour. The database allows us to extract the features diagnostic of particular tephra layers, domes or flows. The diagnostic features include depth in the section, layer thickness and internal stratigraphy, mineral assemblage, major and trace element composition, tephra componentry and granulometry, and radiocarbon age. At the present time, the database can be queried to show all layers of a particular depth, composition, age, etc., using standard statements of the Structured Query Language (SQL). Our goal is to automate the query and report process so that all location data can be queried simultaneously to produce derived tables containing maximum likelihood estimates of vent location, eruption type and eruption age. By statistical analysis of the information in the derived tables, we may be able to produce estimates of future vent locations and times of eruption.

  20. ROTATION OF CORONAL MASS EJECTIONS DURING ERUPTION

    SciTech Connect

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

    2009-06-01

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

  1. 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.

  2. CHAIN RECONNECTIONS OBSERVED IN SYMPATHETIC ERUPTIONS

    SciTech Connect

    Joshi, Navin Chandra; Magara, Tetsuya; Schmieder, Brigitte; Aulanier, Guillaume; Guo, Yang E-mail: njoshi98@gmail.com

    2016-04-01

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

  3. 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

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Donnelly-Nolan, Julie M.; Grove, Timothy L.; Lanphere, Marvin A.; Champion, Duane E.; Ramsey, David W.

    2008-10-01

    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 km 2 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 km 3, giving an overall effusion rate of ˜ 1.2 km 3 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 basalts erupted

  6. 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

  7. 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.

  8. Eruption Products and Collection Methods for the 2008 Summit Eruption of Kilauea Volcano, Hawai'i

    NASA Astrophysics Data System (ADS)

    Wooten, K. M.; Thornber, C. R.; Swanson, D. A.; Ellis, J. F.; Orr, T. R.; Patrick, M. R.; Rausch, J.

    2008-12-01

    After several weeks of elevated sulfur dioxide emissions at Kilauea's summit, a new fumarole appeared low on the southeast wall of Halema'uma'u Crater in mid-March 2008. At 0258 H.s.t. on March 19, an explosive eruption at Halema'uma'u's fumarole created a crater approximately 35 m across. Since that explosive eruption, a gas plume, with variable amounts of ash, has continuously emanated from the vent. Lithic debris was strewn over approximately 50 hectares, but no juvenile material was erupted during the March 19 event. On March 24, however, Pele's hair, Pele's tears, and glass-coated lithics were found on the crater's rim. These samples were the first juvenile material erupted at Kilauea's summit since 1982. After the March 19 explosive eruption, five more significant explosive eruptions have occurred, each of which erupted juvenile and lithic material. Several methods have been used to collect tephra from this eruption. A 10-station network of ash collectors was set up in an array to track changes in fallout from the continuous plume and to calculate a daily accumulation rate. Ash and tephra samples for petrologic and geochemical analysis are collected from wooden boxes placed along the crater's rim. Meter-scale squares on the ground downwind of the vent were cleared of older debris to help recognize new tephra. The samples are classified in 10 categories, based on a variety of characteristics, such as juvenile and lithic component, texture, and appearance. This classification scheme has been devised to help distinguish among the diverse suite of erupted material.

  9. Adalimumab-induced lichenoid drug eruption.

    PubMed

    El Habr, Constantin; Meguerian, Zarouwi; Sammour, Rita

    2014-01-01

    Tumor necrosis factor (TNF)-α inhibitors are being widely and increasingly used for the management of a spectrum of rheumatologic diseases that are refractory to conventional disease modifying anti-rheumatic drugs. Various cutaneous side effects have been reported after treatment with TNF-α inhibitors. We present a case report of a 26-year-old male patient who developed a lichenoid drug eruption few months after the initiation of adalimumab for the management of Crohn's disease. We also highlight the clinical and histopathologic differences between lichenoid drug eruptions and idiopathic lichen planus.

  10. Mt. Pinatubo Volcano - Post Eruption, Luzon, Philippines

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Mt. Pinatubo on the island of Luzon (15.5N, 120.0E) erupted catastrophically in June 1991 after over 600 years of inactivity. This is the first shuttle post eruption photo. The north facing crater is not obvious in this scene but the blowout area, in the once heavily forested region, is easily observed as lava flow, ash fallout, mud slide and debris trails mar the landscape. Clark AFB, once the crossroads of the SW Pacific can only partially be seen.

  11. Time Series of North Pacific Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Dehn, J.; Worden, A. K.; Webley, P. W.

    2011-12-01

    The record of volcanic eruptions was gathered from the 1986 eruption of Augustine Volcano to present for Alaska, Kamchatka and the Kuriles Islands. In this time over 400 ash producing eruptions were noted, and many more events that produced some other activity, e.g. lava, lahar, small explosion, seismic crisis. This represents a minimum for the volcanic activity in this region. It is thought that the records for Alaska are complete for this time period, but it is possible that activity in the Kuriles and Kamchatka could have been overlooked, particularly smaller events. For the Alaska region, 19 different volcanoes have been active in this time. Mt. Cleveland shows the most activity over the time period (40 % likely to have activity in a 3 month period), followed closely by Pavlof (34% likely)volcano. In Kamchatka only 7 volcanoes have been active, Shiveluch is the most active (83% likely) followed by Bezymianny and Kliuchevskoi volcanoes (tied at 60%). The Kuriles only has had 4 active volcanoes, and only 6 known eruptions. Overall this region is one of the most active in the world, in any 3 month period there is a 77% likelihood of volcano activity. For well instrumented volcanoes, the majority of activity is preceded by significant seismicity. For just over half of the events, explosive activity is preceded by thermal signals in infrared satellite data. Rarely (only about 5% of the time) is a stand alone thermal signal not followed within 3 months by an explosive eruption. For remaining events where an ash plume begins the activity, over 90% of the cases show a thermal signal the eruption. The volcanoes with the most activity are the least likely to produce large ash plumes. Conversely the volcanoes that erupt rarely often begin with larger ash producing events. Though there appears to be a recurrent progression of volcanic activity down the chain from east to west, this may be an artifact of several independent systems, each working at their own rate, that

  12. 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.

  13. Global science: the eruption of Krakatau.

    PubMed

    Dörries, Matthias

    2003-01-01

    The eruption of the volcano Krakatau in the Netherlands East Indies (Indonesia) in 1883 had worldwide impact. This was perceived in the three quite different types of global propagation that occurred after the eruption: a rapid pressure wave, noticeable only to measuring instruments, followed a few hours later by the spread of the news of the event, succeeded by a slowly expanding optical phenomenon that lasted for a couple of years. Krakatau was the first natural catastrophe of global magnitude that was almost immediately recognized as such throughout the world, largely thanks to the recently installed worldwide telegraphic network.

  14. 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

  15. Eruption Source Parameters for Recent Icelandic Eruptions and Their Implications for Duration and Termination of Events

    NASA Astrophysics Data System (ADS)

    Thordarson, T.

    2015-12-01

    Since 1947, Iceland has featured 26 volcanic eruptions (2.5 eruptions/year). These include events at the central volcanoes Hekla, Eyjafjallajökull, Grímsvötn and Askja and the fissure eruptions of Surtsey 1963-67 and Nornahraun 2014-15. Of these, 11 are effusive, 8 are mixed (explosive to effusive) and 6 are within-glacier events. Surtsey is the only emergent submarine event (1309 days; 1 km3). Duration of effusive eruptions spans 0.3 to 181 days, with volume, average and peak magma discharge ranging from 10-5-1.6 km3, 0.5-123 m3/s and 1-370 m3/s. Similarly, the mixed events have durations spanning 2.8 to 393 days with volume, average and peak magma discharge ranging from 0.03-0.87 km3, 14-617 m3/s and 50-35600 m3/s. Duration of within-glacier events spans 4.4 to 14 days with volume, average and peak magma discharge ranging from 0.05-0.27 km3, 9-440 m3/s and 400-14000 m3/s. The discharge profiles for these eruptions are highly variable. Mixed eruptions often feature intense discharge (1500 to 40000 m3/s) at the onset of eruption (lasting hours), but some start in a much more subdued manner (500-1000 m3/s). This initial phase is followed by low (3-20 m3/s) magma discharge lasting for weeks to months that normally terminates abruptly. The onset of effusive eruptions is typified by modest discharge (10's to 100's m3/s). They can be very abrupt (<1 day), or drawn out for weeks to months with discharge dropping steadily throughout. The within-glacier events are short-lived explosive events, although with highly varied intensity (see above), and appear to terminate rather abruptly. Plots of eruption duration against size or discharge exhibits no systematic correlation suggesting that none of the eruption source parameters exert principal control on eruption duration or termination. However, these parameters may play a role in conjunction with other factors such as the nature of the lithostratigraphic succession and the local stress field at the eruption site.

  16. 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.

  17. 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

  18. On an Unified Scaling Law for Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Cannavo, F.; Nunnari, G.

    2014-12-01

    Volcanoes constitute dissipative systems with many degrees of freedom. Their eruptions are the result of complex processes that involve interacting chemical-physical systems. At the present, both analytical and numerical models are unable to include all the possible dynamics involved into eruptions. On the other hand, the knowledge of eruption duration can be a key factor for natural hazard estimation. In this work, analyzing a large database with most of all the known volcanic eruptions, we have determined that the duration of eruptions can be described by a unique universal distribution which fully governs eruption duration dynamics. In particular, after the well-known results proposed in literature concerning the seismicity (i.e. the Gutenberg-Richter law), we present an Earth-wise power-law distribution of durations of volcanic eruptions that holds from worldwide to local scales, for different volcanic environments and for all the considered eruption types.

  19. Solar Prominence Eruption Marks 1 Million on Helioviewer

    NASA Video Gallery

    This movie of a prominence eruption on April 20, 2013, was the millionth movie made on Helioviewer.org. The wispy eruption seen here eventually blossomed into a much larger cloud of solar material,...

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. Multiwavelength Observations of a Slow-rise, Multistep X1.6 Flare and the Associated Eruption

    NASA Astrophysics Data System (ADS)

    Yurchyshyn, V.; Kumar, P.; Cho, K.-S.; Lim, E.-K.; Abramenko, V. I.

    2015-10-01

    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) the 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.

  5. Multiwavelength Observations of a Slow Raise, Multi-Step X1.6 Flare and the Associated Eruption

    NASA Astrophysics Data System (ADS)

    Yurchyshyn, V.

    2015-12-01

    Using multi-wavelength observations we studied a slow rise, multi-step X1.6 flare that began on November 7, 2014 as a localized eruption of core fields inside a δ-sunspot and later engulfed the entire active region. 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, IRIS spacecraft along with the ground based data from the New Solar Telescope (NST) present evidence that i) the 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 an in-situ formation of an unstable flux rope observed only in hot AIA channels (131 and 94Å) and LASCO C2 coronagraph images; iii) the global PEA system spanned the entire AR and was due to global scale reconnection occurring at heights of about one solar radii, indicating on the global spatial and temporal scale of the eruption.

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

    SciTech Connect

    Yurchyshyn, V.; Kumar, P.; Cho, K.-S.; Lim, E.-K.; Abramenko, V. I.

    2015-10-20

    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) the 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.

  7. 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.

  8. 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

  9. Geodetic constraints for the mechanism of Anatahan eruption of May 2003

    NASA Astrophysics Data System (ADS)

    Watanabe, Tsuyoshi; Tabei, Takao; Matsushima, Takeshi; Kato, Teruyuki; Nakada, Setsuya; Yoshimoto, Mitsuhiro; Chong, Raymon; Camacho, Juan Takai

    2005-08-01

    Anatahan Island is located at the southern end of the Mariana volcanic chain. On May 10, 2003, the eastern crater of the island erupted for the first time in recorded history. The Plinian eruption column reached an altitude as high as 13 km on May 11, and a thick layer of ash covered the island. The eruptive activity continued to June 2003, but most of the erupted material was expelled during the first week. The volcanic activity declined in the second half of 2003, but resumed in April 2004. In order to determine crustal deformation associated with the eruption, we conducted GPS measurements in July 2003 at a benchmark (ANAT) located approximately 7 km west-northwest of the active crater, where GPS campaign measurements had been repeated four times since 1992. In the period from January to July 2003 during the eruption, significant subsidence - as much as 21 cm - was detected, but horizontal movement was negligible. We began taking continuous GPS measurements at the same site in July 2003 to monitor the transient deformation that was probably associated with magma migration. To assess the spatial extent of the deformation more accurately, we established another permanent GPS site (ANA2) at a site approximately 3 km from the active crater in the northeastern part of the island in January 2004. The coordinates of this time series at ANAT probably show a change in trends at the beginning of 2004. Another subsidence of 2.8 cm and a westward motion of 2.1 cm were estimated to have occurred in the period from July to December 2003. This was followed by an uplift of 5.2 cm and movement in an eastward direction of 1.0 cm in the period from January to June 2004. We developed three preliminarily models of inflation/deflation sources for three different time periods. During the period from January to July 2003, a deformation source was located beneath the ANAT site and acted as a deflation source. Considering the gap in the GPS time series and errors in data (especially

  10. The September 1988 intracaldera avalanche and eruption at Fernandina volcano, Galapagos Islands

    USGS Publications Warehouse

    Chadwick, W.W.; De Roy, T.; Carrasco, A.

    1991-01-01

    During 14-16 September 1988, a large intracaldera avalanche and an eruption of basaltic tephra and lava at Fernandina volcano, Galapagos, produced the most profound changes within the caldera since its collapse in 1968. A swarm of eight earthquakes (mb 4.7-5.5) occurred in a 14 h period on 24 February 1988 at Fernandina, and two more earthquakes of this size followed on 15 April and 20 May, respectively. On 14 September 1988, another earthquake (mb 4.6) preceded a complex series of events. A debris avalanche was generated by the failure of a fault-bounded segment of the east caldera wall, approximately 2 km long and 300 m wide. The avalanche deposit is up to 250 m thick and has an approximate volume of 0.9 km3. The avalanche rapidly displaced a preexisting lake from the southeast end of the caldera floor to the northwest end, where the water washed up against the lower part of the caldera wall, then gradually seeped into the avalanche deposit and was completely gone by mid-January 1989. An eruption began in the caldera within about 1-2 h of the earthquake, producing a vigorous tephra plume for about 12 h, then lava flows during the next two days. The eruption ended late on 16 September. Most of the eruptive activity was from vents on the caldera floor near the base of the new avalanche scar. Unequivocal relative timing of events is difficult to determine, but seismic records suggest that the avalanche may have occurred 1.6 h after the earthquake, and field relations show that lava was clearly erupted after the avalanche was emplaced. The most likely sequence of events seems to be that the 1988 feeder dike intruded upward into the east caldera wall, dislocated the unstable wall block, and triggered the avalanche. The avalanche immediately exposed the newly emplaced dike and initiated the eruption. The exact cause of the earthquakes is unknown. ?? 1991 Springer-Verlag.

  11. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  13. 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.

  14. Burst conditions of explosive volcanic eruptions recorded on microbarographs

    USGS Publications Warehouse

    Morrissey, M.M.; Chouet, B.A.

    1997-01-01

    Explosive volcanic eruptions generate pressure disturbances in the atmosphere that propagate away either as acoustic or as shock waves, depending on the explosivity of the eruption. Both types of waves are recorded on microbarographs as 1- to 0.1-hertz N-shaped signals followed by a longer period coda. These waveforms can be used to estimate burst pressures end gas concentrations in explosive volcanic eruptions and provide estimates of eruption magnitudes.

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

    NASA Astrophysics Data System (ADS)

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

    1984-05-01

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

  16. Bringing the world to a standstill: an investigation into the effects of a Novarupta scale volcanic eruption on today's aviation industry

    NASA Astrophysics Data System (ADS)

    Welchman, R. A.

    2010-12-01

    Novarupta erupted in Alaska on 6th June 1912 and was the biggest of the 21st century. It erupted for 60 hours and sent an ash cloud over 32,000m into the air. People were stranded for several days, houses destroyed, villages abandoned and food supplies disrupted for a long period after the eruption. Ash was recorded to have travelled over 9,500km away in Africa, demonstrating potentially global impacts. The eruption occurred when Alaska had very little aviation industry, today however the airspace above Alaska is one of the busiest in the world. The eruption in Iceland in 2010 which disrupted the European airspace for several weeks and closed it completely for five days, brought to light just how disruptive a volcanic eruption can be, even in countries where volcanic activity is not considered a hazard. It was an expensive event for the aviation industry and caused much disruption. Simulations of a Katmai scale eruption were run in the ‘present-day’, using the PUFF ash fall model. Simulations were run for one week from the start the eruption. A ‘worst-case’ scenario is presented based on data from 2005-2009. It is a hypothetical eruption started on 17th January 2005 and it shows that ash is likely to cause havoc in North America, Europe and parts of Asia. At least 43 airports on average would be severely affected each day of the simulation, leading to several of the major air routes being affected. Where financial data is available, an estimated cost of this event is presented. A 500 hr simulation is presented to demonstrate the possible global effects that could occur within three weeks of an eruption. It shows ash being transported across the equator at high altitudes to the southern hemisphere in Asia as well as the whole of the northern hemisphere being engulfed. The complex implications an eruption like this would have on national and international infrastructures is presented. The results could aid further scientific studies, governmental bodies and

  17. Lichenoid drug eruption after human papillomavirus vaccination.

    PubMed

    Laschinger, Mary E; Schleichert, Rachel A; Green, Brian

    2015-01-01

    Lichenoid drug reactions have been linked to a long and growing list of medications, most of which are used mainly in adults, making these reactions exceedingly rare in children. To the best of our knowledge, this case report is the first of a lichenoid drug eruption in a child after human papillomavirus vaccination.

  18. Monster Prominence Erupts from the Sun

    NASA Video Gallery

    When a rather large M 3.6 class flare occurred near the edge of the Sun on Feb. 24, 2011, it blew out a gorgeous, waving mass of erupting plasma that swirled and twisted for 90 minutes. NASA’s So...

  19. Eruptive history of Mount Katmai, Alaska

    USGS Publications Warehouse

    Hildreth, Edward; Fierstein, Judith

    2012-01-01

    Compositionally, products of Mount Katmai represent an ordinary medium-K arc array, both tholeiitic and calcalkaline, that extends from 51.6% to 72.3% SiO2. Values of 87Sr/86Sr range from 0.70335 to 0.70372, correlating loosely with fractionation indices. The 5–6 km3 of continuously zoned andesite-dacite magma (58%–68% SiO2) that erupted at Novarupta in 1912 was withdrawn from beneath Mount Katmai and bears close compositional affinity with products of that edifice, not with pre-1912 products of the adjacent Trident cluster. Evidence is presented that the 7–8 km3 of high-silica rhyolite (77% SiO2) released in 1912 is unlikely to have been stored under Novarupta or Trident. Pre-eruptive contiguity with the andesite-dacite reservoir is suggested by (1) eruption of ∼3 km3 of rhyolite magma first, followed by mutual mingling in fluctuating proportions; (2) thermal and redox continuity of the whole zoned sequence despite the wide compositional gap; (3) Nd, Sr, O isotopic, and rare earth element (REE) affinities of the whole array; (4) compositional continuity of the nearly aphyric rhyolite with the glass (melt) phase of the phenocryst-rich dacite; and (5) phase-equilibrium experiments that indicate similar shallow pre-eruptive storage depths (3–6 km) for rhyolite, dacite, and andesite.

  20. Advances in the diagnosis of drug eruptions.

    PubMed

    de la Torre, C; Suh Oh, H J

    2013-11-01

    Drug eruptions affecting the skin or mucosas (toxicoderma) are the most common adverse effects of drugs and represent one of the more common diagnostic challenges for the dermatologist. A better understanding of the pathogenic mechanisms of drug reactions, pharmacogenetics, and pharmacoepidemiology will help us to resolve the main dilemmas and to anticipate and even prevent such reactions. Many drug eruptions are due to T cell-mediated hypersensitivity reactions that can involve activation of different proinflammatory mechanisms, which would explain the varied manifestations. Some aspects defy the classical understanding of antigen processing and presentation. New immunological hypotheses, such as the «p-i concept», have been introduced to complement the hapten theory and, at least in part, help to explain why drug reactions tend to affect the skin and why certain viral infections increase the risk of drug eruptions. In this paper we analyze these pathogenic concepts and the role of HLA genes in the susceptibility to certain severe adverse drug reactions, and also examine other advances in the diagnosis of drug eruptions. We briefly discuss a number of recently described reactions to new drugs.

  1. Kaposi's varicelliform eruption: A case series

    PubMed Central

    Ferrari, Bruno; Taliercio, Vanina; Luna, Paula; Abad, María Eugenia; Larralde, Margarita

    2015-01-01

    Kaposi's varicelliform eruption is a rare and potentially fatal viral infection caused mainly by reactivation of herpes simplex virus. It concomitantly occurs with pre-existing skin conditions, mostly atopic dermatitis, so it is predominately found in children. We present a case series that includes four adults, familial cases, and previously healthy patients. We also highlight clinical features, associations and therapeutic options. PMID:26753139

  2. IMAGING PROMINENCE ERUPTIONS OUT TO 1 AU

    SciTech Connect

    Wood, Brian E.; Howard, Russell A.; Linton, Mark G.

    2016-01-10

    Views of two bright prominence eruptions trackable all the way to 1 AU are here presented, using the heliospheric imagers on the Solar TErrestrial RElations Observatory (STEREO) spacecraft. The two events first erupted from the Sun on 2011 June 7 and 2012 August 31, respectively. Only these two examples of clear prominence eruptions observable this far from the Sun could be found in the STEREO image database, emphasizing the rarity of prominence eruptions this persistently bright. For the 2011 June event, a time-dependent 3D reconstruction of the prominence structure is made using point-by-point triangulation. This is not possible for the August event due to a poor viewing geometry. Unlike the coronal mass ejection (CME) that accompanies it, the 2011 June prominence exhibits little deceleration from the Sun to 1 AU, as a consequence moving upwards within the CME. This demonstrates that prominences are not necessarily tied to the CME's magnetic structure far from the Sun. A mathematical framework is developed for describing the degree of self-similarity for the prominence's expansion away from the Sun. This analysis suggests only modest deviations from self-similar expansion, but close to the Sun the prominence expands radially somewhat more rapidly than self-similarity would predict.

  3. ISOON-Based Investigation of Solar Eruptions

    DTIC Science & Technology

    2013-10-30

    2013.]................9 Approved for public release; distribution is unlimited. ii 1. Introduction Space weather is a growing concern for modern ...public release; distribution is unlimited. Table of Contents 1 Introduction ...the flare impulsive phase, the identified main acceleration phase of CMEs in eruptive flares. This research was published in the Astrophysical

  4. Fixed drug eruption due to ornidazole.

    PubMed

    Gupta, Ramji

    2014-11-01

    A 56-year-old male developed an ulcer on his glans penis and mucosae of upper and lower lips 3 days after taking ofloxacin, cephalexin, and ornidazole. Clinically, a provisional diagnosis of fixed drug eruption was made. The causative drug was confirmed by an oral provocation test which triggered a reactivation of all lesions only with ornidazole.

  5. Fixed drug eruption related to fluconazole.

    PubMed

    Lai, Olivia; Hsu, Sylvia

    2016-04-18

    Fixed drug eruption (FDE) is a type of cutaneous drug reaction that occurs at the same sites upon re-exposure to specific medications. Herein we discuss the case of a 23-year-old man with a FDE to fluconazole.

  6. Gas Eruptions Taper Off in Northwestern Oklahoma.

    ERIC Educational Resources Information Center

    Preston, Don

    1980-01-01

    Describes the eruption of inflammable natural gas from the ground surface in the Edith area near Camp Houston. Determining the source of the gas, the results established the Chester-Oswago interval as the most likely source. The surface venting has declined steadily; the likelihood of finding its cause is also described. (SK)

  7. Volcanic twilights from the fuego eruption.

    PubMed

    Volz, F E

    1975-07-04

    Striated twilight glows have been observed since 26 November 1974 in New England, indicating the spread of stratospheric dust earlier observed over Arizona. Similar photometric results were obtained from New Mexico and Florida, and twilights in Puerto Rico showed features not hitherto measured. Letters and verbal reports indicate the source to be eruptions of Fuego Volcano in Guatemala between 13 and 23 October 1974.

  8. Holocene eruptions of mauna kea volcano, hawaii.

    PubMed

    Porter, S C

    1971-04-23

    Postglacial lava flows, interstratified with thick locally derived sheets of tephra, cover some 27.5 square kilometers on the south slope of Mauna Kea. Most of the volcanics were erupted about 4500 years ago and overlie a regionally extensive paleosol which developed largely during the last glaciation.

  9. 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.

  10. Poverty reduction in Africa

    PubMed Central

    Collier, Paul

    2007-01-01

    Poverty in Africa has been rising for the last quarter-century, while it has been falling in the rest of the developing world. Africa's distinctive problem is that its economies have not been growing. This article attempts to synthesize a range of recent research to account for this failure of the growth process. I argue that the reasons lie not in African peculiarities but rather in geographic features that globally cause problems but that are disproportionately pronounced in Africa. These features interact to create three distinct challenges that are likely to require international interventions beyond the conventional reliance on aid. PMID:17942702

  11. Poverty reduction in Africa.

    PubMed

    Collier, Paul

    2007-10-23

    Poverty in Africa has been rising for the last quarter-century, while it has been falling in the rest of the developing world. Africa's distinctive problem is that its economies have not been growing. This article attempts to synthesize a range of recent research to account for this failure of the growth process. I argue that the reasons lie not in African peculiarities but rather in geographic features that globally cause problems but that are disproportionately pronounced in Africa. These features interact to create three distinct challenges that are likely to require international interventions beyond the conventional reliance on aid.

  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. The Mechanisms for the Onset and Explosive Eruption of Coronal Mass Ejections and Eruptive Flares

    NASA Technical Reports Server (NTRS)

    Karpen, Judith T.; Antiochos, Spiro K.; DeVore, Carl Richard

    2012-01-01

    We have investigated the onset and acceleration of coronal mass ejections (CMEs) and eruptive flares. To isolate the eruption physics, our study uses the breakout model, which is insensitive to the energy buildup process leading to the eruption. We performed 2.5D simulations with adaptive mesh refinement that achieved the highest overall spatial resolution to date in a CME/eruptive flare simulation. The ultra-high resolution allows us to separate clearly the timing of the various phases of the eruption. Using new computational tools, we have determined the number and evolution of all X- and O-type nulls in the system, thereby tracking both the progress and the products of reconnection throughout the computational domain. Our results show definitively that CME onset is due to the start of fast reconnection at the breakout current sheet. Once this reconnection begins, eruption is inevitable; if this is the only reconnection in the system, however, the eruption will be slow. The explosive CME acceleration is triggered by fast reconnection at the flare current sheet. Our results indicate that the explosive eruption is caused by a resistive instability, not an ideal process. Moreover, both breakout and flare reconnections begin first as a form of weak tearing characterized by a slowly evolving plasmoids, but eventually transition to a fast form with well-defined Alfvenic reconnection jets and rapid flux transfer. This transition to fast reconnection is required for both CME onset and explosive acceleration. We discuss the key implications of our results for CME/flare observations and for theories of magnetic reconnection.

  14. 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.

  15. 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.

  16. The Laki (Skaftár Fires) and Grímsvötn eruptions in 1783 1785

    NASA Astrophysics Data System (ADS)

    Thordarson, Th; Self, S.

    1993-05-01

    The Laki (Skaftár Fires) fissure eruption in southern Iceland lasted for eight months during 1783 to 1784, and produced one of the largest basaltic lava flows in historic times (14.7±1.0 km3). In addition, neighboring Grímsvötn central volcano was frequently active during the period from May 1783 to May 1785. The combined activity is interpreted as having been the result of a two-year-long volcano-tectonic episode on the Grímsvötn volcanic system. Contemporary descriptions of the explosive activity make it possible to relate the tephra stratigraphy to the progress of the eruption on a weekly basis and show that activity on the fissures propagated to the NE with time, towards Grímsvötn. The eruption at Laki began on 8 June with a brief explosive event on a short fissure, and lava rapidly began to flow into the Skaftá river gorge. It reached the lowlands, 35 km away, four days later and continued to flow, with variable discharge, until 7 February 1784. Approximately 90% of the lava was emplaced in the first five months of activity. The 27-km-long vent complex is composed of ten en echelon fissures distributed on both sides of the much older Laki hyaloclastite mountain. The surface expression of each fissure is a continuous row of vents consisting of scoria cones, spatter cones, and tuff cones. Six tephra fall units are positively identified; two units are completely compsed of phreatomagmatic tephra derived from two tuff cones and the others are Strombolian deposits. The volume of tephra, including ash fall that extended to mainland Europe, is 0.4 km3 dense rock equivalent volume, or 2.6% of the total erupted volume. Interpretation of contemporary descriptions of tephra falls, combined with the preserved stratigraphy, allow the identification of ten eruptive episodes during the eight months of activity on the Laki fissures. These eruptive episodes are inferred to have resulted from the unsteady flow of magma in the feeder system. In addition, at least eight

  17. ON THE ERUPTION OF CORONAL FLUX ROPES

    SciTech Connect

    Fan, Y.

    2010-08-10

    We present three-dimensional MHD simulations of the evolution of the magnetic field in the corona where the emergence of a twisted magnetic flux tube is driven at the lower boundary into a pre-existing coronal potential arcade field. Through a sequence of simulations in which we vary the amount of twisted flux transported into the corona before the emergence is stopped, we investigate the conditions that lead to a dynamic eruption of the resulting coronal flux rope. It is found that the critical condition for the onset of eruption is for the center of the flux rope to reach a critical height at which the corresponding potential field declines with height at a sufficiently steep rate, consistent with the onset of the torus instability of the flux rope. In some cases, immediately after the emergence is stopped, the coronal flux rope first settles into a quasi-static rise with an underlying sigmoid-shaped current layer developing. Preferential heating of field lines going through this current layer may give rise to the observed quiescent X-ray sigmoid loops before eruption. Reconnections in the current layer during the initial quasi-static stage is found to add detached flux to the coronal flux rope, allowing it to rise quasi-statically to the critical height and dynamic eruption of the flux rope then ensues. By identifying field lines whose tops are in the most intense part of the current layer during the eruption, we deduce the evolution and morphology of the post-flare X-ray loops and the flare ribbons at their footpoints.

  18. Products of a Subglacial Flood Basalt Eruption

    NASA Astrophysics Data System (ADS)

    Gorny, C. F.; White, J. D. L.; Gudmundsson, M. T.

    2015-12-01

    The Snæbýlisheiði unit, SE Iceland, is a ca. 26 km³ elongate, flat-topped ridge of volcaniclastic debris coupled with and intruded by coherent basalt stretching over 34 km from the eruption site perpendicular to the rift fissure source. It formed from a single subglacial flood basalt eruption during a recent glaciation, and its elongation reflects glacial control on dispersal via the hydraulic potential gradient at the glacier's base, which drove towards the glacier terminus the meltwater+debris formed during the eruption by quenching and fragmentation. High magma discharge and outgassing drove segregation of magma into down-flow propagating intrusions. Edifice growth was mediated by the extent of ice melting, extent and efficiency of meltwater+debris drainage, and hydraulic gradients locally favoring meltwater accumulation. Eruption style reflected magma flux, edifice stability, and accessibility of water to the vent area via flooding or infiltration. Deposits reflect these competing factors in their chaotic internal organization and stratigraphy, limited lithofacies continuity, and diverse particle populations from multiple source vents. Linear growth of the ridge down-gradient from the eruption site was driven primarily by propagation and continuous fragmentation of shoaling intrusions that formed an interconnected intrusive complex with extensive peperites. Advance was along gently meandering and locally bifurcating sub-ice conduits within hyaloclastite with sheet-lobe levees and lobate fingered intrusions. Irregular dikes, apophyses, horns, and tendrils extended from the main body and generated voluminous lapilli tuff and contorticlasts while providing additional heat to the system. Prolonged transport and deposition of debris produced complexly bedded volcaniclastic deposits derived from and intruded by the basalt sheet. The bedding and depositional features of volcaniclastic debris and relationship to their adjacent intrusions suggest transport and

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. Precursory seismicity associated with the May 29, 2010 undersea eruption south of Sarigan Island, Northern Mariana Islands

    NASA Astrophysics Data System (ADS)

    Searcy, C. K.; Power, J. A.; Webley, P.

    2010-12-01

    On May 29, 2010 at approximately 1148 UTC, an undersea volcano south of Sarigan Island in the Northern Marianna Islands erupted sending an ash plume to 40,000 feet (12.2 km) ASL. Pre-eruptive seismicity associated with this event was recorded on three short-period seismic stations, SARN located on Sarigan Island, ANNE and ANA2, both located on the island of Anatahan. The presumed vent location is about 16 km south east of Sarigan Island and about 30 km north east of Anatahan. Small volcano tectonic earthquakes were recorded on SARN in early April at a rate of 0-1 per day. S-P phase arrivals for these earthquakes place the source of the VT’s between 12.3 km to 16.8 km from station SARN. VT activity continued to increase into May with a maximum of 20 earthquakes per day occurring on May 12. The largest VT’s associated with this eruption occurred on May 20, with most events on this day having coda lengths of 20 to 30 seconds. On May 27 tremor-like waveforms began to show up on Sarigan and Anatahan stations. These events had durations of 3 to 7 minutes with emergent arrivals and no clear S phase. The frequency content of these waveforms is variable with some events showing low frequency content (below 5 HZ) with higher frequency banding and others having a broadband signal. At about 2252 UTC on May 28, these events merged into a continuous signal lasting nearly 30 minutes. A roughly 4 hour period of relative quiescence followed punctuated by individual low frequency events. Another burst of continuous tremor then began at about 0305 UTC on May 29, which lasted about 4.5 hours. During the tail end of this activity a mixture of VT’s and low frequency events are seen. Another period of relative quiescence with the occurrence of very small VT’s then followed for about 4.5 hours. A ramp up of activity began about 11 minutes before the plume producing event occurred at approximately 1148 UTC on May 29. Based on eye witness observations of water discoloration and

  4. 3-d Visualization of Earthquakes and Erupting Vents in Time-series Animations: Application to Kilauea and Miyakejima volcanoes

    NASA Astrophysics Data System (ADS)

    Wright, T. L.

    2003-12-01

    Computer programs have been developed to view erupting vents and earthquake sequences on and beneath transparent topography shown by a DEM, vertical image, or map. In a single frame an earthquake dataset can be rotated with the mouse to create perspective views. Multiple-frame time animations are created in which the perspective (e.g., map, cross-section) and time increments (e.g., hour, day, month) are chosen by the user. Viewed as movies, the animations allow recognition of seismicity patterns occurring over large areas and long time periods. Departures from characteristic activity are easily spotted and can be further investigated in a single frame or in animation with shorter time increments. Time animations have been made of earthquake sequences accompanying several eruptions of Kilauea volcano and the Miyakejima eruption and associated dike emplacement in 2000. An earthquake swarm shallower than 6 km beneath Miyakejima island began on the evening of 6/26/2000. The seismicity moved to the southwest, then to the north and offshore, and a submarine eruption occurred on the morning of 6/27. Shortly thereafter, earthquakes of M 4 and above migrated westward, also becoming deeper (to 20 km), marking the emplacement of a large dike northwest of Miyakejima island. Eruptions at Miyakejima from 7/8 to 9/1 were associated with formation of a new caldera. The timing and location of the submarine eruption can be seen in the seismicity, consistent with later visual observation of discolored seawater and photographs obtained of the seafloor vents. Seismicity associated with the submarine eruption plunges eastward. Seismic sequences preceding explosive eruptions at Miyakejima summit in August plunge southwest. Intersection of the opposed dips occurs near 10 km depth, consistent with existence of a deeper basaltic reservoir feeding the explosive eruptions. Sequences of vertical, pipe-like seismicity extending to very shallow depths over the propagating dike and occurring over

  5. 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.

  6. Contemporary Problems in Africa.

    ERIC Educational Resources Information Center

    O'Meara, Patrick; Winchester, N. Brian

    1987-01-01

    Provides a brief overview of political and economic developments of the past 25 years in Africa. Maintains this was a period of experimentation with vast differences in the ways in which governments dealt with human and natural problems. (JDH)

  7. Child Labour in Africa.

    ERIC Educational Resources Information Center

    Bonnet, Michel

    1993-01-01

    The question of child labor in Africa is complicated by the failures of the educational system, family relations, traditional forms of apprenticeship, proliferation of the informal economic sector, and continuing existence of a rural economy. Hazardous working conditions prevail. (SK)

  8. Epidemiology of rickettsioses in North Africa.

    PubMed

    Letaïef, Amel

    2006-10-01

    The first description of Mediterranean spotted fever (MSF) was made by Conor and Brush in 1910 in Tunisia, where, at the same time, Nicolle described the role of lice in transmission of epidemic typhus. However, along this century, there have been few and fragmentary reports about ecology and epidemiology of rickettsioses in North Africa. This region was always considered, for these diseases, like other Mediterranean regions. The most human tick-borne rickettsiosis known to occur in North Africa is MSF caused by R. conorii and transmitted by the brown dog tick, Rhipicephalus sanguineus. Recent studies showed that other arthropode-transmitted rickettsiae are prevalent in North Africa: R. aeschlimannii, R. massiliae, and R. felis. Moreover, R. felis and R. aeschlimannii human infection were respectively confirmed, by serology in Tunisia, and by PCR in Morocco. The seroprevalence of R. conorii among healthy population was ranging from 5% to 8% in most of the countries. Epidemiological and clinical features are frequently resumed in an eruptive fever with eschar occurring in hot season in rural areas. Typhus group rickettsioses, caused by R. typhi and R. prowazekii are less frequently reported than in the 1970s. Seroprevalence of R. typhi among blood donors was from 0.5% to 4%. In Algeria about 2% of febrile patients had R. prowazekii antibodies. Moreover, reemerging threat of epidemic typhus should be considered, after the two cases recently diagnosed in the highlands of Algeria. Murine typhus, considered as "benign" typhus, is underestimated. When R. typhi was inserted in serologic tests, murine typhus became more frequently confirmed. In a recent study in Central Tunisia, we confirmed an emergence of murine typhus mistaken for R. conorii or viral infection. In addition to typhus surveillance, future studies have to determine which spotted fever group rickettsiae are prevalent in vectors and in human pathology.

  9. Mass Flux of Tephra Sampled Frequently During the Ongoing Halema`uma`u Eruption (Invited)

    NASA Astrophysics Data System (ADS)

    Swanson, D.; Wooten, K.; Orr, T. R.

    2009-12-01

    The ongoing summit eruption of Kilauea provides an unparalleled opportunity to track, almost daily, the production of tephra. The eruption began on 19 March 2008, and tephra has been erupted every day since then to the end of August 2009. Most of the time, tephra is ejected quasi-continuously from the vent accompanied by a light gray to white gas plume, occasionally broken by a more vigorous pulse (“brown plume”) richer in ejecta. In early April 2008, an array of 10 plastic buckets was placed within 400 m of the new vent in Halema`uma`u down the prevailing NE wind direction. The configuration of the array, spanning an area of about 73,000 m2, has not changed since then. Buckets are emptied frequently, initially every day and, since summer 2008, on all weekdays. The contents are dried and weighed, and an “average network accumulation rate” is calculated in g/m2/hour. In addition, componentry analyses are made of the >0.5-mm size fraction from a bucket near the vent, in order to categorize the tephra into juvenile and lithic fractions. To estimate the total mass of tephra ejected from the vent for a given collection, we first drew isomass contours for several daily collections and plotted isomass versus square root of area to obtain the total mass of the deposit. From this, we developed an empirical multiplication factor that allows us to estimate, within ~25 percent, the total ejected mass per day in kilograms from the total collected mass in grams. The tephra is a mix of vitric and lithic pyroclasts, mostly ash in size. The vitric clasts, interpreted as juvenile, include Pele’s hair and tears, hollow spherules, dumbbells, pumice, and bits of coarsely vesicular glass. All these clasts were probably produced by weak spattering at the top of the lava column, which has rarely been seen. Especially since fall 2008, some vitric clasts are partly coated with secondary minerals or rock dust. We interpret such clasts as recycled, first erupted during spattering

  10. Astronomy Landscape in Africa

    NASA Astrophysics Data System (ADS)

    Nemaungani, Takalani

    2015-01-01

    The vision for astronomy in Africa is embedded in the African Space Policy of the African Union in early 2014. The vision is about positioning Africa as an emerging hub for astronomy sciences and facilities. Africa recognized the need to take advantage of its natural resource, the geographical advantage of the clear southern skies and pristine sites for astronomy. The Pan African University (PAU) initiative also presents an opportunity as a post-graduate training and research network of university nodes in five regions of Africa and supported by the African Union. The Southern African node based in South Africa concentrates on space sciences which also includes astronomy. The PAU aims to provide the opportunity for advanced graduate training and postgraduate research to high-performing African students. Objectives also include promoting mobility of students and teachers and harmonizing programs and degrees.A number of astronomy initiatives have burgeoned in the Southern African region and these include the Southern Africa Largest Optical Telescope (SALT), HESS (High Energy Stereoscopic System), the SKA (Square Kilometre Array) and the AVN (African Very Long Baseline Interferometer Network). There is a growing appetite for astronomy sciences in Africa. In East Africa, the astronomy community is well organized and is growing - the East African Astronomical society (EAAS) held its successful fourth annual conference since 2010 on 30 June to 04 July 2014 at the University of Rwanda. Centred around the 'Role of Astronomy in Socio-Economic Transformation,' this conference aimed at strengthening capacity building in Astronomy, Astrophysics and Space Science in general, while providing a forum for astronomers from the region to train young and upcoming scientists.

  11. AIDS in Africa

    DTIC Science & Technology

    2006-03-09

    have recommended that Africans infected with HIV be treated with an antibiotic/ sulfa drug combination known as cotrimoxazole in order to prevent...response is the subject of much debate. An estimated 500,000 Africa AIDS patients were being treated with antiretroviral drugs in mid-2005, up from 150,000...whether drugs can be made widely accessible without costly health infrastructure improvements. U.S. concern over AIDS in Africa grew in the 1980s, as the

  12. Profile of South Africa

    SciTech Connect

    Fox, G.J.; Tonneson, L.C.

    1996-08-01

    A broad overview of the Republic of South Africa`s nuclear energy program is presented. Economic aspects are the main focus of the article, and numerical data is provided for electricity generation and use and uranium production. The role of the molecular laser isotope process for enrichment is discussed. The research reactor program, waste disposal and decommissioning, mining history, uranium production, and nonproliferation policy are other highlighted topics.

  13. 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

  14. Investigating the pre- and post-eruptive stress regime at Redoubt volcano, Alaska, from 2008-1010 using seismic anisotropy and stress-tensor inversions

    NASA Astrophysics Data System (ADS)

    Gardine, M.; Roman, D. C.

    2010-12-01

    Redoubt volcano, located on the west side of Cook Inlet approximately 170 km southwest of Anchorage, Alaska, began erupting in March 2009. The eruption, which consisted of at least 17 explosive events over a three-week time period followed by three months of dome-building, significantly impacted both aviation and oil production operations in the area. Pre-eruptive seismicity was generally limited to deep (>20 km) long-period (DLP) earthquakes starting in late 2008, transitioning to bursts of strong, shallow volcanic tremor for nearly three months prior to the eruption. The near-complete absence of precursory volcano-tectonic (VT) earthquakes is unusual for eruptions of this type and complicates understanding of the dynamics of the Redoubt magmatic system. However, the strong volcanic tremor preceding the eruption suggests that magma was ascending and the system was pressurizing for months prior to the first explosion - a situation during which VT earthquakes typically occur. The study of subtle changes in stress conditions at Redoubt may elucidate the reasons for the observed near-complete lack of precursory VT seismicity. Using first-motion data from waveforms recorded by seismic stations operated in the vicinity of Redoubt by the Alaska Volcano Observatory (AVO) and the Alaska Earthquake Information Center (AEIC), we computed double-couple fault-plane solutions for approximately 200 VT earthquakes occurring in the months prior to and immediately following the first eruption in March 2009. The analysis of the fault-plane solutions using spatial and temporal stress-tensor inversions combined with cumulative misfit analysis will help to constrain if, when, and where localized precursory changes in stress occurred. In addition, we performed an analysis of shear-wave splitting using data from deep slab events located by AEIC within a 70 km radius for one year prior to and one year following the eruption, which resulted in approximately 500 high-quality measurements on

  15. 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

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

    NASA Astrophysics Data System (ADS)

    Wade, Jennifer A.; Plank, Terry; Stern, Robert J.; Tollstrup, Darren L.; Gill, James B.; O'Leary, Julie C.; Eiler, John M.; Moore, Richard B.; Woodhead, Jon D.; Trusdell, Frank; Fischer, Tobias P.; Hilton, David R.

    2005-08-01

    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.% SiO 2, and are otherwise homogeneous (varying less than 3% 2 σ 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.% SiO 2). The large proportion of lavas with silicic compositions at Anatahan (> 59 wt.% SiO 2) 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 δ18O, 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

  17. Monitoring of the volcanic rock compositions during the 2012-2013 fissure eruption at Tolbachik volcano, Kamchatka

    NASA Astrophysics Data System (ADS)

    Volynets, Anna O.; Edwards, Benjamin R.; Melnikov, Dmitry; Yakushev, Anton; Griboedova, Irina

    2015-12-01

    Here we present the results from monitoring of the composition of rocks produced during the 2012-2013 fissure eruption at Tolbachik volcano (FTE). Major and trace element concentrations in 75 samples are reported. Products of this eruption are represented by high alumina basaltic trachyandesites with higher alkalis and titanium contents than in all previously studied rocks of the Tolbachik monogenetic volcanic field. Rocks erupted during the first three days (27-30 November) from the northern (also called Menyailov) group of vents are the most silica- and alkali-rich (SiO2 concentrations up to 55.35 wt.% and K2O up to 2.67 wt.%). From December onwards, when the eruptive activity switched from the Menyailov vents to the southern (Naboko) group of vents, silica content dropped by 2 wt.%, concentrations of MgO, FeO, TiO2 and Mg# increased, and K2O and Na2O concentrations and K2O/MgO ratio decreased. For the rest of the eruption the compositions of rocks remained constant and homogeneous; no systematic compositional differences between lava, bombs and scoria samples are evident. Trace element distributions in the rocks of the Menyailov and Naboko vent lavas are relatively uniform; Menyailov lavas have slightly higher Th, Nb, Hf, Y, and HREE concentrations than the Naboko vent lavas at more or less constant element ratios. We explain the initial change in geochemistry by tapping of a slightly cooler and fractionated (~ 3% Mt and 8% Cpx) upper part of the magma storage zone before the main storage area began to feed the eruption. Thermodynamic constraints show that apparent liquidus temperatures varied from 1142 °C to 1151 °C, and thermodynamic modeling shows that variations in compositions are consistent with a high degree of low pressure (100-300 MPa), nominally anhydrous fractionation of a parent melt compositionally similar to the 1975 Northern Breakthrough high-Mg basalt. Geochemistry, petrological observations and modeling are in agreement with the newly erupted

  18. The death of a Strombolian eruption: Evidence for dyke drainage from Red Crater, Tongariro volcano, New Zealand

    NASA Astrophysics Data System (ADS)

    Wadsworth, F. B.; von Aulock, F. W.; Kennedy, B.; Branney, M.; Bardsley, C. J.

    2010-12-01

    How volcanic eruptions stop is poorly understood. We present data from a dyke in the wall of Red Crater, Tongariro volcano, NZ, that record the closing stages of an eruption. The 1.85ka eruption began with andesite effusion followed by Strombolian eruption of basaltic andesite. It terminated with withdrawal of basaltic andesite from a shallow level dyke accompanied by a last gasp of phreatic explosivity. The dyke is twice as wide within the upper poorly consolidated scoria as it is within underlying better consolidated brecciated lava. In lower parts near the boundary between the lava breccia and scoria the dyke is full, whereas at higher levels both dyke marginal zones are preserved with a spectacular evacuated interior. Detailed field mapping and textural analysis of crystallinities and vesicularities using >5mm vesicles, reveal three texturally distinct facies. (1) A glassy marginal facies with 12% vesicularity, margin-parallel flow banding and fabric defined by a preferred orientation of small phenocrysts (20-30% vol.). (2) A fully crystalline lower central zone with phenocrysts (50% vol.) randomly orientated and variably elongate vesicles (32% vol.). (3) An upper, almost completely crystalline central facies with subhorizontal flow banding arranged in en-echelon arrays, subhorizontally orientated phenocrysts (45-50% vol.) and patchy development of sub-spherical vesicles (vesicularity varies from 18-24% vol.). Coating the evacuated dyke interior is 1-2m finely laminated, fine-grained palagonitized ash. We interpret the three facies to correspond to three phases of magma movement. Facies 1 is related to rapid freezing against the dyke margins during vertical eruption. Facies 2 relates to a waning eruption during which the dyke widened. Facies 3 records the draining body of magma in retreat, during which the magma level stepped inward, preserving subhorizontal, 0.2-0.5m wide “bathtub rings” on the interior wall of the dyke marginal zone. The rings occur 2m

  19. Decolonizing Bioethics in Africa

    PubMed Central

    Macaulay-Adeyelure, O.C.

    2017-01-01

    The global spread of bioethics from its North-American and European provenance to non-Western societies is currently raising some concerns. Part of the concern has to do with whether or not the exportation of bioethics in its full Western sense to developing non-Western states is an instance of ethical imperialism or bioethical neocolonialism. This paper attempts an exploration of this debate in the context of bioethics in sub-Saharan Africa. Rather than conceding that bioethics has a colonial agenda in Africa, this paper defends the position that the current bioethics trend in sub-Saharan Africa is an unintended imperialistic project. It argues that its colonizing character is not entirely a product of the Western programmed goals of training and institution building; rather, it is a structural consequence of many receptive African minds and institutions. Though bioethics in Africa is turning out as a colonizing project, one serious implication of such trend, if unchecked urgently, is that bioethics’ invaluable relevance to Africa is being incapacitated. This paper, therefore, attempts a decolonizing trajectory of bioethics in Africa. Contrary to the pretense of ‘African bioethics,’ which some African scholars are now defending, this paper through the logic of decolonization makes case for ‘bioethics in Africa’. In such logic, the principle of existential needs is prioritized over the principle of identity and authenticity that define African voice in bioethics. PMID:28344985

  20. Eruption Pattern of Dentition and Its Medico-legal Significance.

    PubMed

    Karki, R K

    2016-01-01

    Background The eruption pattern of temporary and permanent teeth are fairly constant with the growing age. So the age determination of an individual by examination of teeth is one of the accepted methods in legal system. A review of the literature shows there are differences in eruption pattern between different populations mainly due to variations in the constitutions and environment, so highlighting the importance of this study to the Nepalese population. Objective To assess the eruption age of temporary and permanent teeth in Nepalese population and compared the eruption age with other groups. Method This cross-sectional study, included 450 subjects, aged between six months to 25 years selected by simple random sampling method. The determinant variable such as age and number of teeth was recorded. Result Eruption of temporary and permanent teeth is slightly delayed in Nepalese population compared with others. First temporary tooth to erupt is lower central Incisor at around eight months and last to erupt is second molar at around 28 months. For permanent tooth, first molar erupts at around seven years and second molar erupts by 14 years. Eruption of third molar (wisdom tooth) varies from 18 to 25 years. Conclusion This study provides a model data on eruption age of teeth which is first study of its kind in Nepal. The findings of this study will help as a reference data for optimal use in clinical, academic and research activities especially in Nepalese population. Medico legally it helps in estimation of age along with other parameters.

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

    SciTech Connect

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

    2013-07-10

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. Pu'u 'O'o-Kupaianaha 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

    Pu`u `O`o - Kupaianaha eruption on the east rift zone of Kilauea, 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 `O`o vent (episodes 4-47). In July 1986, after two days of fissure eruptions up- and downrift from Pu`u `O`o (episodes 48a and 48b), the eruption shifted to a new vent, K?paianaha, 3.5 km downrift. For the next five-and-a-half years (episode 48), K?paianaha was the site of nearly continuous low-level effusion. The 49th episode occurred in November 1991, when several fissures opened between Pu`u `O`o and K?paianaha (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 Kupaianaha 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 `O`o 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 K?paianaha was active, the Pu`u `O`o 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 `O`o pond drained at the beginning of episode 49 in November 1991, and

  4. 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)

  5. Ionospheric disturbances by volcanic eruptions by GNSS-TEC: Comparison between Vulcanian and Plinian eruptions

    NASA Astrophysics Data System (ADS)

    Nakashima, Y.; Heki, K.; Takeo, A.; Cahyadi, M. N.; Aditiya, A.

    2014-12-01

    Acoustic waves from volcanic eruptions are often observed as infrasound in near fields. Part of them propagate upward and disturb the ionosphere, and can be observed in Total Electron Content (TEC) data derived by Global Navigation Satellite System (GNSS) receivers. In the past, Heki (2006 GRL) detected ionospheric disturbances by the 2004 explosion of the Asama Volcano, central Japan, and Dautermann et al. (2009 JGR) studied the 2003 eruption of the Soufriere Hills volcano in Montserrat, West Indies. Here we present new examples, and try to characterize such disturbances. We first show TEC disturbances by the 2014 February Plinian eruption (VEI 4) of the Kelud volcano, East Java, Indonesia (Figure), observed with a regional GNSS network.The 2014 Kelud eruption broke a lava dome made by 2007 eruption and created a new creator. Significant disturbances were detected with four GPS and two GLONASS satellites, and the wavelet analyses showed that harmonic oscillations started at ~16:25 UT and continued nearly one hour. The frequency of the oscillation was ~3.8 mHz, which coincides with the atmospheric fundamental mode. We also confirmed concentric wavefronts, moving outward by ~0.8m/sec (stronger signals on the northern side). These features are similar to the 2003 Soufriere Hills case, although the signals in the present Kelud case is much clearer. Next, we compare them with ionospheric disturbances by Vulcanian explosions that occurred recently in Japan, i.e. the 2004 Asama case and the 2009 Sakurajima, and the 2011 Shin-moedake eruptions. They are characterized with one-time N-shaped disturbances possibly excited by the compression of the air above the vents. On the other hand, data from nearby seismometers suggested that atmospheric oscillations of various frequencies were excited by this continuous Plinian eruption. Part of such oscillations would have grown large due to atmospheric resonance.

  6. THE BEHAVIOR OF NOVAE LIGHT CURVES BEFORE ERUPTION

    SciTech Connect

    Collazzi, Andrew C.; Schaefer, Bradley E.; Xiao Limin; Pagnotta, Ashley; Kroll, Peter; Loechel, Klaus; Henden, Arne A.

    2009-12-15

    In 1975, E. R. Robinson conducted the hallmark study of the behavior of classical nova light curves before eruption, and this work has now become part of the standard knowledge of novae. He made three points: 5 out of 11 novae showed pre-eruption rises in the years before eruption, one nova (V446 Her) showed drastic changes in the variability across eruptions, and all but one of the novae (excepting BT Mon) have the same quiescent magnitudes before and after the outburst. This work has not been tested since it came out. We have now tested these results by going back to the original archival photographic plates and measuring large numbers of pre-eruption magnitudes for many novae using comparison stars on a modern magnitude scale. We find in particular that four out of five claimed pre-eruption rises are due to simple mistakes in the old literature, that V446 Her has the same amplitude of variations across its 1960 eruption, and that BT Mon has essentially unchanged brightness across its 1939 eruption. Out of 22 nova eruptions, we find two confirmed cases of significant pre-eruption rises (for V533 Her and V1500 Cyg), while T CrB has a deep pre-eruption dip. These events are a challenge to theorists. We find no significant cases of changes in variability across 27 nova eruptions beyond what is expected due to the usual fluctuations seen in novae away from eruptions. For 30 classical novae plus 19 eruptions from 6 recurrent novae, we find that the average change in magnitude from before the eruption to long after the eruption is 0.0 mag. However, we do find five novae (V723 Cas, V1500 Cyg, V1974 Cyg, V4633 Sgr, and RW UMi) that have significantly large changes, in that the post-eruption quiescent brightness level is over ten times brighter than the pre-eruption level. These large post-eruption brightenings are another challenge to theorists.

  7. 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

  8. 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.

  9. Mammalian enamel maturation: Crystallographic changes prior to tooth eruption

    PubMed Central

    Kallistová, Anna; Horáček, Ivan; Šlouf, Miroslav; Skála, Roman; Fridrichová, Michaela

    2017-01-01

    Using the distal molar of a minipig as a model, we studied changes in the microstructural characteristics of apatite crystallites during enamel maturation (16-23 months of postnatal age), and their effects upon the mechanical properties of the enamel coat. The slow rate of tooth development in a pig model enabled us to reveal essential heterochronies in particular components of the maturation process. The maturation changes began along the enamel-dentine junction (EDJ) of the trigonid, spreading subsequently to the outer layers of the enamel coat to appear at the surface zone with a 2-month delay. Correspondingly, at the distal part of the tooth the timing of maturation processes is delayed by 3-5 month compared to the mesial part of the tooth. The early stage of enamel maturation (16-20 months), when the enamel coat is composed almost exclusively of radial prismatic enamel, is characterized by a gradual increase in crystallite thickness (by a mean monthly increment of 3.8 nm); and an increase in the prism width and thickness of crystals composed of elementary crystallites. The late stage of maturation (the last two months prior to tooth eruption), marked with the rapid appearance of the interprismatic matrix (IPM) during which the crystals densely infill spaces between prisms, is characterized by an abrupt decrease in microstrain and abrupt changes in the micromechanical properties of the enamel: a rapid increase in its ability to resist long-term load and its considerable hardening. The results suggest that in terms of crystallization dynamics the processes characterizing the early and late stage of mammalian enamel maturation represent distinct entities. In regards to common features with enamel formation in the tribosphenic molar we argue that the separation of these processes could be a common apomorphy of mammalian amelogenetic dynamics in general. PMID:28196135

  10. Voluminous Icelandic Basaltic Eruptions Appear To Cause Abrupt Global Warming

    NASA Astrophysics Data System (ADS)

    Ward, P. L.

    2011-12-01

    Beginning on June 21, 1783, Laki volcano in southern Iceland erupted 14.7 km3 basalt, ejecting 24 Mt SO_{2} into the stratosphere where it was blown eastward and northward and 98 Mt into the troposphere where the jet stream transported it southeastward to Europe. The "dry fog" observed in Europe with an estimated mean concentration of 60 ppbv SO2, raised daytime temperatures as much as 3.3^{o}C, causing the warmest July in England from 1659 when measurements began until 1983. SO2, tropospheric O_{3}, NO2, and fine ash absorb ultraviolet energy from the sun that causes the bonds between and within their atoms to oscillate at 47 times higher frequency than the bonds in CO_{2} absorbing infrared radiation. Temperature is proportional to the kinetic energy of these oscillations, i.e. the frequency squared. Thus these gases are raised to much higher temperatures than greenhouse gases. The Stefan-Boltzmann law says that radiation from these molecules is a constant times temperature raised to the fourth power. As a result, SO2 and ash radiate far more energy back to earth than CO_{2}, causing warming. Another way to look at the energy involved shows that 15 ppbv SO2 in the 0.3-0.42 μm wavelength band absorbs as much solar energy per unit volume as 388,000 ppbv CO_{2} absorbs infrared energy in the 12.7-17.5 μm band. Basaltic volcanoes such as Laki emit 10 to 100 times more SO2 than more evolved magmas and are less explosive, leaving most of the SO_{2} in the troposphere. All 14 Dansgaard-Oeschger (DO) sudden warmings between 46 and 11 ka are contemporaneous with the highest levels of sulfate in the GISP2 drill hole near Summit Greenland. These DO events typically warmed the northern hemisphere out of the ice age within decades, but as volcanism waned, ocean temperatures cooled the world back into an ice age within centuries. The world finally exited the ice age when voluminous volcanism continued from 11.6 to 9.6 ka. Basaltic table mountains or tuyas in Iceland document

  11. Kilauea volcano eruption seen from orbit

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The STS-51 crew had a clear view of the erupting Kilauea volcano during the early morning pass over the Hawaiian islands. Kilauea, on the southwest side of the island of Hawaii, has been erupting almost continuously since January, 1983. Kilauea's summit caldera, with the smaller Halemaumau crater nestled within, is highlighted in the early morning sun (just above the center of the picture). The lava flows which covered roads and subdivisions in 1983-90 can be seen as dark flows to the east (toward the upper right) of the steam plumes on this photo. The summit crater and lava flows of Mauna Loa volcano make up the left side of the photo. Features like the Volcano House and Kilauea Visitor Center on the edge of the caldera, the small subdivisions east of the summit, Ola's Rain Forest north of the summit, and agricultural land along the coast are easily identified.

  12. Selective fixed drug eruption to amoxycillin.

    PubMed

    Arias, J; Férnandez-Rivas, M; Panadero, P

    1995-07-01

    A selective fixed drug eruption to amoxycillin but not other betalactam drugs is reported. Penicillins are the drugs most frequently implicated in immunological adverse reactions. The most important of these are allergic reactions where an IgE-mediated mechanism is well established. Other immunological mechanisms have been described in reactions, such as haemolytic anaemia, serum sickness, drug-induced nephritis, drug fever and contact dermatitis. Fixed drug eruption (FDE) is a type of drug-induced dermatosis, the immunopathogenesis of which remains unknown. FDE is an uncommon reaction to penicillin derivatives, and very few cases have been reported. We present a case of a selective FDE to amoxycillin (AX), with no reaction to other betalactam drugs. Although one similar case has been reported, the reactivity to other penicillin derivatives was not assessed.

  13. Localized Eruptive Blue Nevi after Herpes Zoster

    PubMed Central

    Colson, Fany; Arrese, Jorge E.; Nikkels, Arjen F.

    2016-01-01

    A 52-year-old White man presented with a dozen small, well-restricted, punctiform, asymptomatic, blue-gray macules on the left shoulder. A few months earlier, he had been treated with oral acyclovir for herpes zoster (HZ) affecting the left C7–C8 dermatomes. All the blue macules appeared over a short period of time and then remained stable. The patient had not experienced any previous trauma or had tattooing in this anatomical region. The clinical diagnosis suggested blue nevi. Dermatoscopy revealed small, well-limited, dark-blue, compact, homogeneous areas evoking dermal blue nevi. An excisional biopsy was performed and the histological examination confirmed a blue nevus. As far as we are aware of, this is the first report of eruptive blue nevi following HZ, and it should be included in the differential diagnosis of zosteriform dermatoses responding to an isotopic pathway. In addition, a brief review concerning eruptive nevi is presented. PMID:27462219

  14. Learning to recognize volcanic non-eruptions

    USGS Publications Warehouse

    Poland, Michael P.

    2010-01-01

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

  15. An Erupted Dilated Odontoma: A Rare Presentation

    PubMed Central

    Sharma, Gaurav; Nagra, Amritpreet; Singh, Gurkeerat; Nagpal, Archna; Soin, Atul; Bhardwaj, Vishal

    2016-01-01

    A dilated odontoma is an extremely rare developmental anomaly represented as a dilatation of the crown and root as a consequence of a deep, enamel-lined invagination and is considered a severe variant of dens invaginatus. An oval shape of the tooth lacking morphological characteristics of a crown or root implies that the invagination happened in the initial stages of morphodifferentiation. Spontaneous eruption of an odontoma is a rare occurrence and the occurrence of a dilated odontoma in a supernumerary tooth is even rarer with only a few case reports documented in the English literature. We present an extremely rare case of erupted dilated odontoma occurring in the supernumerary tooth in anterior maxillary region in an 18-year-old male, which, to the best of our knowledge, is the first ever case reported in English literature. PMID:26989523

  16. Fluvial responses to volcanism: resedimentation of the 1800a Taupo ignimbrite eruption in the Rangitaiki River catchment, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Manville, Vern; Newton, Erin H.; White, James D. L.

    2005-02-01

    The potential for the generation of dangerous and damaging lahars and floods in response to the eruption of voluminous pyroclastic debris has become increasingly appreciated in recent years. The style and tempo of this response varies both between eruptions and between individual catchments impacted by a single eruption, so that an understanding of the factors controlling this variation is necessary for precise hazard assessment. The 1800a Taupo eruption from the Taupo Volcanic Centre in the central North Island of New Zealand devastated an area of 20,000 km 2 during eruption of a climactic ignimbrite, impacting the headwaters of all major rivers draining radially from this region. The Rangitaiki River, the subject of this paper, differs from other catchments in that the Taupo ignimbrite buried an essentially flat land surface inherited from a suite of welded ignimbrite sheets erupted between 320-340 and 230 ka. The middle reaches of the catchment are characterised by narrow, steep gorges alternating with low-gradient basins developed in tectonic half-grabens. Initially, remobilisation of pyroclastic material in the headwaters was dominated by hyperconcentrated sheet flows resulting in shallow reworking. In higher gradient areas, reintegration of drainage networks was achieved by incision of deep channels and gullies, assisted by breakouts from ephemeral lakelets developed in ignimbrite-dammed depressions. Braided, and later meandering, streams superseded this pattern as rill and gully systems stabilised and sediment yields fell leading to a decline in drainage density. Gorge reaches acted as efficient conduits for remobilised material while the basins acted as local depocentres for the temporary storage of volcaniclastic sediments, mediating the transfer of pyroclastic debris to the Bay of Plenty coast >100 km to the north. Reworking and resedimentation of pyroclastic debris began immediately after the eruption, peaking early and then rapidly declining so that

  17. Volcanic Lightning in Eruptions of Sakurajima Volcano

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  18. Fixed drug eruptions with intraoral presentation

    PubMed Central

    Srivastava, Rahul; Bihari, Manorama; Bhuvan, Jyoti; Saad, Ahmed

    2015-01-01

    Fixed-drug eruption (FDE) is an unusual and rare adverse drug reaction. This type of reaction is actually a delayed type of hypersensitivity reaction that occurs as lesions recurring at the same skin site due to repeated intake of an offending drug. Here is a case report of a 58-year-old male patient who developed intraoral FDEs after ingestion of the first dose of ornidazole. PMID:26097341

  19. Solar eruptions: The CME-flare relationship

    NASA Astrophysics Data System (ADS)

    Vršnak, B.

    2016-11-01

    Coronal mass ejections (CMEs), caused by large-scale eruptions of the coronal magnetic field, often are accompanied by a more localized energy release in the form of flares, as a result of dissipative magnetic-field reconfiguration. Morphology and evolution of such flares, also denoted as dynamical flares are often explained as a consequence of reconnection of the arcade magnetic field, taking place below the erupting magnetic flux rope. A close relationship of the CME acceleration and the flare energy release is evidenced by various statistical correlations between parameters describing CMEs and flares, as well as by the synchronization of the CME acceleration phase with the impulsive phase of the associated flare. Such behavior implies that there must be a feedback relation between the dynamics of the CME and the flare-associated reconnection process. From the theoretical standpoint, magnetic reconnection affects the CME dynamics in several ways. First, it reduces the tension of the overlying arcade magnetic field and increases the magnetic pressure below the flux rope, and in this way enhances the CME acceleration. Furthermore, it supplies the poloidal magnetic flux to the flux rope, which helps sustaining the electric current in the rope and prolonging the action of the driving Lorentz force to large distances. The role of these processes, directly relating solar flares and CMEs, is illustrated by employing a simple model, where the erupting structure is represented by a curved flux rope anchored at both sides in the dense/inert photosphere, being subject to the kink and torus instability. It is shown that in most strongly accelerated ejections, where values on the order of 10 km s-2 are attained, the poloidal flux supplied to the erupting rope has to be several times larger than was the initial flux.

  20. Wall-layer eruptions in turbulent flows

    NASA Technical Reports Server (NTRS)

    Walker, J. D. A.

    1989-01-01

    The near-wall region of a turbulent flow is investigated in the limit of large Reynolds numbers. When low-speed streaks are present, the governing equations are shown to be of the boundary-layer type. Physical processes leading to local breakdown and a strong interaction with the outer region are considered. It is argued that convected vortices, predominantly of the hairpin type, will provoke eruptions and regenerative interactions with the outer region.

  1. Acemetacin-induced fixed drug eruption.

    PubMed

    Cebeci, Filiz; Yaşar, Şirin; Aytekin, Sema; Güneş, Pembegül

    2016-01-01

    Fixed drug eruption (FDE) is an adverse effect observed with various drugs such as nonsteroidal anti-inflammatory drugs (NSAIDs) and various antibiotics. Acemetacin, a prodrug of indomethacin, is an NSAID licensed for use in rheumatic disease and other musculoskeletal disorders. We present a case of acemetacin-induced FDE in a 49-year-old woman. To the best of our knowledge, this is the second case report detailing clinical and histopathological findings of a patient with FDE caused by acemetacin.

  2. Terbinafine induced pityriasis rosea-like eruption.

    PubMed

    George, Anisha; Bhatia, Anuradha; Kanish, Bimal; Williams, Abhilasha

    2015-01-01

    Terbinafine is an allylamine antifungal agent which is widely used for the treatment of fungal infections. Cutaneous side effects have been reported in 2% of the patients on terbinafine therapy with many morphological patterns. We report a case of terbinafine induced pityriasis rosea, a very rare side effect of terbinafine. This report emphasizes the importance of counseling the patient to report immediately in the event of a cutaneous eruption.

  3. A Statistical Study of Solar Filament Eruptions

    NASA Astrophysics Data System (ADS)

    Schanche, Nicole; Aggarwal, Ashna; Reeves, Kathy; Kempton, Dustin James; Angryk, Rafal

    2016-05-01

    Solar filaments are cool, dark channels of partially-ionized plasma that lie above the chromosphere. Their structure follows the neutral line between local regions of opposite magnetic polarity. Previous research (e.g. Schmieder et al. 2013, McCauley et al. 2015) has shown a positive correlation (70-80%) between the occurrence of filament eruptions and coronal mass ejections (CME’s). In this study, we attempt to use properties of the filament in order to predict whether or not a given filament will erupt. This prediction would help to better predict the occurrence of an oncoming CME. To track the evolution of a filament over time, a spatio-temporal algorithm that groups separate filament instances from the Heliophysics Event Knowledgebase (HEK) into filament tracks was developed. Filament features from the HEK metadata, such as length, chirality, and tilt are then combined with other physical features, such as the overlying decay index for two sets of filaments tracks - those that erupt and those that remain bound. Using statistical methods such as the Kolmogrov-Smirnov test and a Random Forest Classifier, we determine the effectiveness of the combined features in prediction. We conclude that there is significant overlap between the properties of filaments that erupt and those that do not, leading to predictions only ~5-10% above chance. However, the changes in features, such as a change in the filament's length over time, were determined to have the highest predictive power. We discuss the possible physical connections with the change in these features."This project has been supported by funding from the Division of Advanced Cyberinfrastructure within the Directorate for Computer and Information Science and Engineering, the Division of Astronomical Sciences within the Directorate for Mathematical and Physical Sciences, and the Division of Atmospheric and Geospace Sciences within the Directorate for Geosciences, under NSF award #1443061.”

  4. Terbinafine induced pityriasis rosea-like eruption

    PubMed Central

    George, Anisha; Bhatia, Anuradha; Kanish, Bimal; Williams, Abhilasha

    2015-01-01

    Terbinafine is an allylamine antifungal agent which is widely used for the treatment of fungal infections. Cutaneous side effects have been reported in 2% of the patients on terbinafine therapy with many morphological patterns. We report a case of terbinafine induced pityriasis rosea, a very rare side effect of terbinafine. This report emphasizes the importance of counseling the patient to report immediately in the event of a cutaneous eruption. PMID:26729964

  5. Interplanetary shocks preceded by solar filament eruptions

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Kahler, S. W.; Sheeley, N. R., Jr.

    1986-01-01

    The solar and interplanetary characteristics of six interplanetary shock and energetic particle events associated with the eruptions of solar filaments lying outside active regions are discussed. The events are characterized by the familiar double-ribbon H-alpha brightenings observed with large flares, but only very weak soft X-ray and microwave bursts. Both impulsive phases and metric type II bursts are absent in all six events. The energetic particles observed near the earth appear to be accelerated predominantly in the interplanetary shocks. The interplanetary shock speeds are lower and the longitudinal extents considerably less than those of flare-associated shocks. Three of the events were associated with unusual enhancements of singly-ionized helium in the solar wind following the shocks. These enhancements appear to be direct detections of the cool filament material expelled from the corona. It is suggested that these events are part of a spectrum of solar eruptive events which include both weaker events and the large flares. Despite their unimpressive and unreported solar signatures, the quiescent filament eruptions can result in substantial space and geophysical disturbances.

  6. Characterize Eruptive Processes at Yucca Mountain, Nevada

    SciTech Connect

    D. Krier

    2004-10-04

    The purpose of this scientific analysis report, ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', is to present 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 repository at Yucca Mountain. This scientific analysis report provides information to four other reports: ''Number of Waste Packages Hit by Igneous Intrusion'', (BSC 2004 [DIRS 170001]); ''Atmospheric Dispersal and Deposition of Tephra from Potential Volcanic Eruption at Yucca Mountain, Nevada'' (BSC 2004 [DIRS 170026]); ''Dike/Drift Interactions'' (BSC 2004 [DIRS 170028]); ''Development of Earthquake Ground Motion Input for Preclosure Seismic Design and Postclosure Performance Assessment of a Geologic Repository at Yucca Mountain, NV'' (BSC 2004 [DIRS 170027], Section 6.5). This report is organized into seven major sections. This section addresses the purpose of this document. Section 2 addresses quality assurance, Section 3 the use of software, Section 4 identifies the requirements that constrain this work, and Section 5 lists assumptions and their rationale. Section 6 presents the details of the scientific analysis and Section 7 summarizes the conclusions reached.

  7. Victims from volcanic eruptions: a revised database

    NASA Astrophysics Data System (ADS)

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

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

  8. The role of eruption in solar flares

    NASA Technical Reports Server (NTRS)

    Sturrock, Peter A.

    1989-01-01

    This article focuses on two problems involved in the development of models of solar flares. The first concerns the mechanism responsible for eruptions, such as erupting filaments or coronal mass ejections, that are sometimes involved in the flare process. The concept of 'loss of equilibrium' is considered and it is argued that the concept typically arises in thought-experiments that do not represent acceptable physical behavior of the solar atmosphere. It is proposed instead that such eruptions are probably caused by an instability of a plasma configuration. The instability may be purely MHD, or it may combine both MHD and resistive processes. The second problem concerns the mechanism of energy release of the impulsive (or gradual) phase. It is proposed that this phase of flares may be due to current interruption, as was originally proposed by Alfven and Carlqvist. However, in order for this process to be viable, it seems necessary to change one's ideas about the heating and structure of the corona in ways that are outlined briefly.

  9. Geodetic evidence for lower crustal magma withdrawal during the 2009 eruption of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Cervelli, P. F.; Grapenthin, R.; Freymueller, J. T.

    2009-12-01

    Redoubt volcano, on the western side of Cook Inlet about 100 miles WSW of Anchorage, Alaska began erupting in March 2009. The eruption continued for nearly 3 months, and slow dome growth may still persist. No continuously recording GPS instrumentation existed with 25 km of Redoubt at the beginning of major precursory unrest in January 2009. The closest CPGS instrument at that time was the Plate Boundary Observatory (PBO) backbone station AC17, about 27 km northeast of the volcano's summit. A small GPS campaign network, consisting of about 15 benchmarks, had been established at Redoubt in 2001 and had been partially reoccupied in 2008. In response to the precursory unrest, the Alaska Volcano Observatory deployed continuously recording GPS instruments at five of the campaign benchmarks, though only one of these was telemetered. Several distinct signals appear in the GPS time series, suggesting an interplay of at least two sources ranging in depth from the lower crust to within the volcanic edifice. The most remarkable of these signals, measured more than 25 km from Redoubt at AC17, shows a movement down and toward the volcano coincident in time with the initial onset of extrusion in late March, but ending well before the emplacement of the large, 70 million cubic meter lava dome through mid-April to mid-May that culminated the eruption. Closer stations show an exponentially decaying pattern of deflation that seems to follow the temporal pattern of dome growth. These contrasting styles and scales of deformation almost certainly indicate multiple sources operating over a range of depths. The rapid augmentation of the Redoubt geophysical network with CGPS proved quite useful, not just from the standpoint of engendering scientific research, but also from the perspective of providing short-term forecasts of volcanic hazard. As demonstrated during the recent eruption of Redoubt, as well as at other volcanoes in Alaska and elsewhere, we argue that routine use of CGPS on

  10. Hantaviruses in Africa.

    PubMed

    Witkowski, Peter T; Klempa, Boris; Ithete, Ndapewa L; Auste, Brita; Mfune, John K E; Hoveka, Julia; Matthee, Sonja; Preiser, Wolfgang; Kruger, Detlev H

    2014-07-17

    This paper summarizes the progress in the search for hantaviruses and hantavirus infections in Africa. After having collected molecular evidence of an indigenous African hantavirus in 2006, an intensive investigation for new hantaviruses has been started in small mammals. Various novel hantaviruses have been molecularly identified not only in rodents but also in shrews and bats. In addition, the first African hantavirus, Sangassou virus, has been isolated and functionally characterized in cell culture. Less is known about the ability of these hantaviruses to infect humans and to cause diseases. To date, no hantavirus genetic material could be amplified from patients' specimens collected in Africa. Serological studies in West Africa, based on a battery of screening and confirmatory assays, led to the detection of hantavirus antibodies in the human population and in patients with putative hantavirus disease. In addition to this overview, we present original data from seroepidemiological and field studies conducted in the Southern part of Africa. A human seroprevalence rate of 1.0% (n=1442) was detected in the South African Cape Region whereas no molecular evidence for the presence of hantavirus was found in 2500 small animals trapped in South Africa and Namibia.

  11. Neogene desertification of Africa

    NASA Astrophysics Data System (ADS)

    Senut, Brigitte; Pickford, Martin; Ségalen, Loïc

    2009-08-01

    Throughout the Neogene, the faunas and floras in Africa recorded global climatic changes. We present an overview of Neogene desertification in Africa by tracing stable isotopes in eggshells and mammalian enamel, by faunal (changes in hypsodonty, etc.) and floral changes in sequences at the latitudinal extremities of the continent and the equator. This work reveals that desertification started in the southwest ca 17-16 Ma, much earlier than the region of the present-day Sahara (ca 8-7 Ma) and long before the deserts in East Africa (Plio-Pleistocene). A consequence of this history is that animals and plants inhabiting the South of the continent had a long period of time in which to adapt to arid, unstable climatic conditions. When parts of East Africa became arid during the Late Miocene and Plio-Pleistocene, several of these lineages expanded northwards and occupied developing arid niches before local lineages could adapt. Several of the latter became extinct, while others withdrew westwards as the tropical forest diminished in extent. It is proposed that the history of desertification in Africa was related to that of the polar ice caps (Antarctic, Arctic).

  12. Solar Multiple Eruptions from a Confined Magnetic Structure

    NASA Astrophysics Data System (ADS)

    Lee, Jeongwoo; Liu, Chang; Jing, Ju; Chae, Jongchul

    2016-09-01

    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 encircling 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.

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

    USGS Publications Warehouse

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

    2002-01-01

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

  14. 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

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

  17. Hubble Captures Volcanic Eruption Plume From Io

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Hubble Space Telescope has snapped a picture of a 400-km-high (250-mile-high) plume of gas and dust from a volcanic eruption on Io, Jupiter's large innermost moon.

    Io was passing in front of Jupiter when this image was taken by the Wide Field and Planetary Camera 2 in July 1996. The plume appears as an orange patch just off the edge of Io in the eight o'clock position, against the blue background of Jupiter's clouds. Io's volcanic eruptions blasts material hundreds of kilometers into space in giant plumes of gas and dust. In this image, material must have been blown out of the volcano at more than 2,000 mph to form a plume of this size, which is the largest yet seen on Io.

    Until now, these plumes have only been seen by spacecraft near Jupiter, and their detection from the Earth-orbiting Hubble Space Telescope opens up new opportunities for long-term studies of these remarkable phenomena.

    The plume seen here is from Pele, one of Io's most powerful volcanos. Pele's eruptions have been seen before. In March 1979, the Voyager 1 spacecraft recorded a 300-km-high eruption cloud from Pele. But the volcano was inactive when the Voyager 2 spacecraft flew by Jupiter in July 1979. This Hubble observation is the first glimpse of a Pele eruption plume since the Voyager expeditions.

    Io's volcanic plumes are much taller than those produced by terrestrial volcanos because of a combination of factors. The moon's thin atmosphere offers no resistance to the expanding volcanic gases; its weak gravity (one-sixth that of Earth) allows material to climb higher before falling; and its biggest volcanos are more powerful than most of Earth's volcanos.

    This image is a contrast-enhanced composite of an ultraviolet image (2600 Angstrom wavelength), shown in blue, and a violet image (4100 Angstrom wavelength), shown in orange. The orange color probably occurs because of the absorption and/or scattering of ultraviolet light in the plume. This light from Jupiter passes through

  18. Estimating radiated energy for complex volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Fry, B.; Jolly, A. D.; Ristau, J. P.

    2013-12-01

    The August 6th, 2012 Te Maari eruption in the Tongariro National Park included a complex sequence of activity including a pre-eruption debris avalanche and at least three distinct eruptive pulses. In such a scenario, classic seismic methods such as moment tensor inversion struggle to characterize the whole event due to overlapping coda of the disparate bursts. To understand the entire eruption in terms of energy budget, we determine the trace energy density according to the more general formulations of Kanamori (1977) and Vassiliou and Kanamori (1982). By calculating the broad-band integral of the energy spectrum, we quantify radiated energy from the eruption cycle for each component at 3-component seismic monitoring sites surrounding the volcano and compare these results to observations at mid- and far-field distances. We correct for anelastic attenuation, noting that the solution is relatively insensitive to this correction as the records are essentially within the near-field. This suggests that even near to the source, most of the radiated energy is contained in relatively low frequencies which are less attenuated at short propagation distances. In the double-couple case of earthquakes (for which the method was originally developed), difficulties arise in situations with poor azimuthal data coverage. This is because the energy recorded at a single station is largely influenced by heterogeneous radiation patterns. For the volcano case, volumetric excitations of unknown source geometries may produce similar heterogeneities, which can be averaged by incorporation of well-distributed data. Our results provide estimates of radiated energy (Es) from the sequence ranging from 2.96 x 10^9 to 2.58 X 10^10 N*m, corresponding to an average energy magnitude of Me=3.72. This estimate is significantly lower than the predicted energy release based on an independently calculated moment tensor inversion. Preliminary results suggest that routine full-waveform energy calculations

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  20. 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