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Sample records for mount agung eruption

  1. Mt Agung (Bali) Eruption Plumes

    Atmospheric Science Data Center

    2018-04-04

    ...     View larger image MISR Active Aerosol Plume-Height (AAP) Project: Mt Agung (Bali) eruption plumes seen ... R. Kahn/NASA GSFC Access Project Paper: MISR Active Aerosol Plume-Height (AAP) Project Access and Order MISR Data and ...

  2. Local Community Entrepreneurship in Mount Agung Trekking

    NASA Astrophysics Data System (ADS)

    Mudana, I. G.; Sutama, I. K.; Widhari, C. I. S.

    2018-01-01

    Since its last major eruption in 1963, Mount Agung in Selat District, Karangasem Regency, the highest mountain in Bali Province began to be visited by tourists climbers. Because of the informal obligation that every climbing/trekking should be guided by local guides, since the 1990s, there have been initiatives from a number of local community members to serve climbing tourists who were keen to climb the volcano/mountain. This study was conducted to understand and describe the entrepreneurial practices which appeared in the local surrounding community. Specifically, Selat Village, in guiding the climbing/trekking. This study used qualitative data analysis and its theories were adapted to data needed in the field. The results of study showed that Mount Agung was considered attractive by climbing tourists not only because of the exotic beauty and challenges of difficulty (as well as the level of danger) to conquer it, but also because it kept certain myths from its status as a holy/sacred mountain to Balinese Hindus. In fact, a number of tourists who did the climbing/trekking without being guided very often got lost, harmed in an accident, or fell to their death. As a direct result, all climbing activities require guidance. Especially guides from local community organizations who really understand the intricacies of climbing and the curvature of the mountain. The entrepreneurial practices of Selat Village community had arisen not only to serve usual climbing activities, but also to preserve the environment of the mountain and the safety of the climbing tourists with the many taboos related to the climb. These facts could be seen clearly from descriptions of local experts and local climbing guides who have been doing their work for years. As a form of entrepreneurship, they basically did their work for the main purpose of seeking livelihoods (or making money) but their responsibility as local people made them commit to guarding the sanctity of the mountain. This was

  3. Indonesia's Active Mount Agung Volcano Imaged by NASA Spacecraft

    NASA Image and Video Library

    2017-12-10

    After a new small eruption sent an ash cloud 1.24 miles (2 kilometers) into the sky on Dec. 7, 2017, Indonesia's Mount Agung volcano quieted down. This image was acquired Dec. 8 after the latest activity by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra satellite. The image shows vegetation in red colors. The summit crater has a hot spot (yellow) as detected by ASTER's thermal infrared channels. More than 65,00 residents continue to be evacuated from the volcano's danger zone in case of a major eruption. The image covers an area of 11 by 12.3 miles (17.8 by 19.8 kilometers), and is located at 8.3 degrees south, 115.5 degrees east. https://photojournal.jpl.nasa.gov/catalog/PIA22121

  4. Arctic sea ice response to the eruptions of Agung, El Chichón, and Pinatubo

    NASA Astrophysics Data System (ADS)

    Gagné, M.-È.; Kirchmeier-Young, M. C.; Gillett, N. P.; Fyfe, J. C.

    2017-08-01

    Using a large initial condition ensemble of climate model simulations, we examine the impact of volcanic activity on Arctic sea ice cover from 1960 to 2005, a period that includes three very large tropical eruptions. Ensemble averaging across simulations with natural (volcanic and solar) forcings alone reduces noise due to internal variability to show a decade of increased Arctic sea extent (of up to half a million square kilometers) following each of the Mount Agung (1963), Mount El Chichón (1982), and Mount Pinatubo (1991) eruptions. A similar impact is seen when averaging over a large ensemble of simulations with natural and all-known anthropogenic forcings. We show that the volcanic response in sea ice cover is sensitive to preeruption temperature, with warmer conditions before an eruption being associated with a larger than average response. Finally, a detection and attribution analysis using second-generation Canadian Earth System Model (CanESM2) did not identify a significant response in the observations, while finding no evidence of inconsistency between observations and CanESM2 since regression coefficients were consistent with unity. A similar detection and attribution analysis using the somewhat stronger volcanic response from the simulations in the average of the CMIP5 models did identify a detectable natural forcing response in four observational sea ice extent data sets.

  5. New microphysical volcanic forcing datasets for the Agung, El Chichon and Pinatubo eruptions

    NASA Astrophysics Data System (ADS)

    Dhomse, Sandip; Mann, Graham; Marshall, Lauren; Carslaw, Kenneth; Chipperfield, Martyn; Bellouin, Nicolas; Morgenstern, Olaf; Johnson, Colin; O'Connor, Fiona

    2017-04-01

    Major tropical volcanic eruptions inject huge amounts of SO2 directly into the stratosphere, and create a long-lasting perturbation to the stratospheric aerosol. The abruptly elevated aerosol has strong climate impacts, principally surface cooling via scattering incoming solar radiation. The enhanced tropical stratospheric aerosol can also absorb outgoing long wave radiation causing a warming of the stratosphere and subsequent complex composition-dynamics responses (e.g. Dhomse et al., 2015). In this presentation we apply the composition-climate model UM-UKCA with interactive stratospheric chemistry and aerosol microphysics (Dhomse et al., 2014) to assess the enhancement to the stratospheric aerosol and associated radiative forcings from the three largest tropical eruptions in the last 60 years: Mt Agung (February 1963), El Chichon (April 1982) and Mt. Pinatubo (June 1991). Accurately characterising the forcing signature from these major eruptions is important for attribution of recent climate change and volcanic effects have been identified as a key requirement for robust attribution of multi-decadal surface temperature trends (e.g. Marotzke and Forster, 2015). Aligning with the design of the ISA-MIP co-ordinated multi-model "Historical Eruption SO2 Emissions Assessment" (HErSEA), we have carried out 3-member ensemble of simulations with each of upper, low and mid-point best estimates for SO2 and injection height for each eruption. We evaluate simulated aerosol properties (e.g. extinction, AOD, effective radius, particle size distribution) against a range of satellite and in-situ observational datasets and assess stratospheric heating against temperature anomalies are compared against reanalysis and other datasets. References: Dhomse SS, Chipperfield MP, Feng W, Hossaini R, Mann GW, Santee ML (2015) Revisiting the hemispheric asymmetry in midlatitude ozone changes following the Mount Pinatubo eruption: A 3-D model study, Geophysical Research Letters, 42, pp.3038

  6. 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.

  7. 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. 

  8. 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.

  9. 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.

  10. Potential climate impact of Mount Pinatubo eruption

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lacis, Andrew; Ruedy, Reto; Sato, Makiko

    1992-01-01

    The GISS global-climate model is used to make a preliminary estimate of Mount Pinatubo's climate impact. Assuming the aerosol optical depth is nearly twice as great as for the 1982 El Chichon eruption, the model forecasts a dramatic but temporary break in recent global warming trends. The simulations indicate that Pinatubo occurred too late in the year to prevent 1991 from becoming one of the warmest years in instrumental records, but intense aerosol cooling is predicted to begin late in 1991 and to maximize late in 1992. The predicted cooling is sufficiently large that by mid 1992 it should even overwhelm global warming associated with an El Nino that appears to be developing, but the El Nino could shift the time of minimum global temperature into 1993. The model predicts a return to record warm levels in the later 1990s. The effect is estimated of the predicted global cooling on such practical matters as the severity of the coming Soviet winter and the dates of cherry blossoming next spring.

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

    Treesearch

    Rhonda Mazza; Charlie Crisafulli; Fred Swanson

    2011-01-01

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

  12. Determination of source parameters of the 2017 Mount Agung volcanic earthquake from moment-tensor inversion method using local broadband seismic waveforms

    NASA Astrophysics Data System (ADS)

    Madlazim; Prastowo, T.; Supardiyono; Hardy, T.

    2018-03-01

    Monitoring of volcanoes has been an important issue for many purposes, particularly hazard mitigation. With regard to this, the aims of the present work are to estimate and analyse source parameters of a volcanic earthquake driven by recent magmatic events of Mount Agung in Bali island that occurred on September 28, 2017. The broadband seismogram data consisting of 3 local component waveforms were recorded by the IA network of 5 seismic stations: SRBI, DNP, BYJI, JAGI, and TWSI (managed by BMKG). These land-based observatories covered a full 4-quadrant region surrounding the epicenter. The methods used in the present study were seismic moment-tensor inversions, where the data were all analyzed to extract the parameters, namely moment magnitude, type of a volcanic earthquake indicated by percentages of seismic components: compensated linear vector dipole (CLVD), isotropic (ISO), double-couple (DC), and source depth. The results are given in the forms of variance reduction of 65%, a magnitude of M W 3.6, a CLVD of 40%, an ISO of 33%, a DC of 27% and a centroid-depth of 9.7 km. These suggest that the unusual earthquake was dominated by a vertical CLVD component, implying the dominance of uplift motion of magmatic fluid flow inside the volcano.

  13. Air pressure waves from Mount St. Helens eruptions

    NASA Astrophysics Data System (ADS)

    Reed, Jack W.

    1987-10-01

    Infrasonic recordings of the pressure wave from the Mount St. Helens (MSH) eruption on May 18, 1980, together with the weather station barograph records were used to estimate an equivalent explosion airblast yield for this eruption. Pressure wave amplitudes versus distance patterns were found to be comparable with patterns found for a small-scale nuclear explosion, the Krakatoa eruption, and the Tunguska comet impact, indicating that the MSH wave came from an explosion equivalent of about 5 megatons of TNT. The peculiar audibility pattern reported, with the blast being heard only at ranges beyond about 100 km, is explained by consideration of finite-amplitude shock propagation developments.

  14. Characterization of aerosols from eruptions of mount st. Helens.

    PubMed

    Chuan, R L; Woods, D C; McCormick, M P

    1981-02-20

    Measurements of mass concentration and size distribution of aerosols from eruptions of Mount St. Helens as well as morphological and elemental analyses were obtained between 7 April and 7 August 1980. In situ measurements were made in early phreatic and later, minor phreatomagmatic eruption clouds near the vent of the volcano and in plumes injected into the stratosphere from the major eruptions of 18 and 25 May. The phreatic aerosol was characterized by an essentially monomodal size distribution dominated by silicate particles larger than 10 micrometers in diameter. The phreatomagmatic eruption cloud was multimodal; the large size mode consisted of silicate particles and the small size modes were made up of mixtures of sulfuric acid and silicate particles. The stratospheric aerosol from the main eruption exhibited a characteristic narrow single mode with particles less than 1 micrometer in diameter and nearly all of the mass made up of sulfuric acid droplets.

  15. Characterization of aerosols from eruptions of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Chuan, R. L.; Woods, D. C.; Mccormick, M. P.

    1981-01-01

    Measurements of mass concentration and size distribution of aerosols from eruptions of Mount St. Helens as well as morphological and elemental analyses were obtained between 7 April and 7 August 1980. In situ measurements were made in early phreatic and later, minor phreatomagmatic eruption clouds near the vent of the volcano and in plumes injected into the stratosphere from the major eruptions of 18 and 25 May. The phreatic aerosol was characterized by an essentially monomodal size distribution dominated by silicate particles larger than 10 micrometers in diameter. The phreatomagmatic eruption cloud was multimodal; the large size mode consisted of silicate particles and the small size modes were made up of mixtures of sulfuric acid and silicate particles. The stratospheric aerosol from the main eruption exhibited a characteristic narrow single mode with particles less than 1 micrometer in diameter and nearly all of the mass made up of sulfuric acid droplets.

  16. Eruptions of Mount St. Helens : Past, present, and future

    USGS Publications Warehouse

    Tilling, Robert I.; Topinka, Lyn J.; Swanson, Donald A.

    1990-01-01

    Mount St. Helens, located in southwestern Washington about 50 miles northeast of Portland, Oregon, is one of several lofty volcanic peaks that dominate the Cascade Range of the Pacific Northwest; the range extends from Mount Garibaldi in British Columbia, Canada, to Lassen Peak in northern California. Geologists call Mount St. Helens a composite volcano (or stratovolcano), a term for steepsided, often symmetrical cones constructed of alternating layers of lava flows, ash, and other volcanic debris. Composite volcanoes tend to erupt explosively and pose considerable danger to nearby life and property. In contrast, the gently sloping shield volcanoes, such as those in Hawaii, typically erupt nonexplosively, producing fluid lavas that can flow great distances from the active vents. Although Hawaiian-type eruptions may destroy property, they rarely cause death or injury. Before 1980, snow-capped, gracefully symmetrical Mount St. Helens was known as the "Fujiyama of America." Mount St. Helens, other active Cascade volcanoes, and those of Alaska form the North American segment of the circum-Pacific "Ring of Fire," a notorious zone that produces frequent, often destructive, earthquake and volcanic activity.

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

    USGS Publications Warehouse

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

    2007-01-01

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

  18. Ocular effects following the volcanic eruptions of Mount St Helens.

    PubMed

    Fraunfelder, F T; Kalina, R E; Buist, A S; Bernstein, R S; Johnson, D S

    1983-03-01

    Three hundred thirty-two ophthalmologists examined 1,523 patients with immediate ocular complaints following the 1980 eruptions of Mount St Helens. Loggers working up to 18 months in environments with high concentrations of volcanic ash were compared with a control group of loggers without volcanic ash contact. Although the ash particles acted as ocular foreign bodies, the small particles were apparently well tolerated for the most part, except for acute irritation. Patients with contact lenses or sicca syndrome had the most frequent ocular complaints. To date, no long-term ocular effects have been noted secondary to volcanic ash exposure.

  19. 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

  20. A comparison of constituents of Mount St. Helens eruption clouds with those of some other volcanoes

    NASA Technical Reports Server (NTRS)

    Cadle, R. D.; Heidt, L.

    1982-01-01

    Gases from Mount St. Helens were collected from the eruption clouds using an airplane during the period April 2 to April 8, 1980, and were analyzed for CO2, H2, CH4, and COS. The results were of similar magnitude to those obtained from magmatic eruptions in Central America. Thus, although the eruptions were evidently largely phreatic, magmatic gases may have played a larger role in these early small eruptions than has generally been believed. Electron micrographs of ash particles collected from the Mount St. Helens eruption clouds showed that the particles were for the most part much larger than those from the Central American eruptions.

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

    NASA Astrophysics Data System (ADS)

    Aloatem Tazifor, A. N.

    2016-02-01

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

  2. Trajectories of the mount st. Helens eruption plume.

    PubMed

    Danielsen, E F

    1981-02-20

    The plume of the major eruption of Mount St. Helens on 18 May 1980 penetrated 10 to 11 kilometers into the stratosphere, attaining heights of 22 to 23 kilometers. Wind shears rapidly converted the plume from an expanding vertical cone to a thin, slightly inclined lamina. The lamina was extruded zonally in the stratosphere as the lower part moved eastward at jet stream velocities, while the upper part slowly moved westward in the region of nonsteady transition from the westerlies to the summer stratospheric easterlies. Trajectories computed to position the NASA U-2 aircraft for sampling in the plume are described. Plume volume after 8 hours of strong volcanic emission is estimated at 2 x 10(6) cubic kilometers. Only about 1 percent of this volume is attributed to the volcano; the rest was entrained from the environment.

  3. Trajectories of the Mount St. Helens eruption plume

    NASA Technical Reports Server (NTRS)

    Danielsen, E. F.

    1981-01-01

    The plume of the major eruption of Mount St. Helens on May 18, 1980 penetrated 10 to 11 km into the stratosphere, attaining heights of 22 to 23 km. Wind shears rapidly converted the plume from an expanding vertical cone to a thin, slightly inclined lamina. The lamina was extruded zonally in the stratosphere as the lower part moved eastward at jet stream velocities, while the upper part slowly moved westward in the region of nonsteady transition from the westerlies to the summer stratospheric easterlies. Trajectories computed to position the NASA U-2 aircraft for sampling in the plume are described. Plume volume after 8 hours of strong volcanic emission is estimated at 2,000,000 cu km. Only about 1% of this volume is attributed to the volcano; the rest was entrained from the environment.

  4. Air pressure waves from Mount St. Helens eruptions

    SciTech Connect

    Reed, J.W.

    1987-10-20

    Weather station barograph records as well as infrasonic recordings of the pressure wave from the Mount St. Helens eruption of May 18, 1980, have been used to estimate an equivalent explosion airblast yield for this event. Pressure amplitude versus distance patterns in various directions compared with patterns from other large explosions, such as atmospheric nuclear tests, the Krakatoa eruption, and the Tunguska comet impact, indicate that the wave came from an explosion equivalent of a few megatons of TNT. The extent of tree blowdown is considerably greater than could be expected from such an explosion, and the observed forest damagemore » is attributed to outflow of volcanic material. The pressure-time signature obtained at Toledo, Washington, showed a long, 13-min duration negative phase as well as a second, hour-long compression phase, both probably caused by ejacta dynamics rather than standard explosion wave phenomenology. The peculiar audibility pattern, with the blast being heard only at ranges beyond about 100 km, is explicable by finite amplitude propagation effects. Near the source, compression was slow, taking more than a second but probably less than 5 s, so that it went unnoticed by human ears and susceptible buildings were not damaged. There was no damage as Toledo (54 km), where the recorded amplitude would have broken windows with a fast compression. An explanation is that wave emissions at high elevation angles traveled to the upper stratosphere, where low ambient air pressures caused this energetic pressure oscillation to form a shock wave with rapid, nearly instantaneous compression. Atmospheric refraction then returned part of this wave to ground level at long ranges, where the fast compressions were clearly audible. copyright American Geophysical Union 1987« less

  5. The Mount Ruapehu eruption, 1996: a review of potential health effects.

    PubMed

    Weinstein, P; Patel, A

    1997-12-01

    Literature search and consultation with New Zealand experts were used to review the potential health effects of explosive volcanic eruptions, and possibilities for their control, in the context of the 1996 eruption and possible future eruptions of Mount Ruapehu. Humans may be exposed to several types of hazardous ejecta during and after volcanic eruptions. Such exposure may cause health effects that could require surveillance and control, but health effects in New Zealand are unlikely to be detectable while eruptions remain small and infrequent. The existing health surveillance systems in New Zealand are adequate to monitor and help control the possible health effects of volcanic eruptions.

  6. Quantifying probabilities of eruptions at Mount Etna (Sicily, Italy).

    NASA Astrophysics Data System (ADS)

    Brancato, Alfonso

    2010-05-01

    based on seismological and volcanological data, integrated with strain, geochemical, gravimetric and magnetic parameters. In the code, is necessary to fix an appropriate forecasting time window. On open-conduit volcanoes as Mt. Etna, a forecast time window of a month (as fixed in other applications worldwide) seems unduly long, because variations of the state of the volcano (significant variation of a specific monitoring parameter could occur in time scale shorter than the forecasting time window) are expected with shorter time scale (hour, day or week). This leads to set a week as forecasting time window, coherently with the number of weeks in which an unrest has been experienced. The short-term vent opening hazard assessment will be estimated during an unrest phase; the testing case (2001 July eruption) will include all the monitoring parameters collected at Mt. Etna during the six months preceding the eruption. The monitoring role has been assessed eliciting more than 50 parameters, including seismic activity, ground deformation, geochemistry, gravity, magnetism, and distributed inside the first three nodes of the procedure. Parameter values describe the Mt. Etna volcano activity, being more detailed through the code, particularly in time units. The methodology allows all assumptions and thresholds to be clearly identified and provides a rational means for their revision if new data or information are incoming. References Newhall C.G. and Hoblitt R.P.; 2002: Constructing event trees for volcanic crises, Bull. Volcanol., 64, 3-20, doi: 10.1007/s0044500100173. Marzocchi W., Sandri L., Gasparini P., Newhall C. and Boschi E.; 2004: Quantifying probabilities of volcanic events: The example of volcanic hazard at Mount Vesuvius, J. Geophys. Res., 109, B11201, doi:10.1029/2004JB00315U. Marzocchi W., Sandri, L. and Selva, J.; 2008: BET_EF: a probabilistic tool for long- and short-term eruption forecasting, Bull. Volcanol., 70, 623 - 632, doi: 10.1007/s00445-007-0157-y.

  7. Frequent eruptions of Mount Rainier over the last ∼2,600 years

    USGS Publications Warehouse

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

    2009-01-01

    Field, geochronologic, and geochemical evidence from proximal fine-grained tephras, and from limited exposures of Holocene lava flows and a small pyroclastic flow document ten–12 eruptions of Mount Rainier over the last 2,600 years, contrasting with previously published evidence for only 11–12 eruptions of the volcano for all of the Holocene. Except for the pumiceous subplinian C event of 2,200 cal year BP, the late-Holocene eruptions were weakly explosive, involving lava effusions and at least two block-and-ash pyroclastic flows. Eruptions were clustered from ∼2,600 to ∼2,200 cal year BP, an interval referred to as the Summerland eruptive period that includes the youngest lava effusion from the volcano. Thin, fine-grained tephras are the only known primary volcanic products from eruptions near 1,500 and 1,000 cal year BP, but these and earlier eruptions were penecontemporaneous with far-traveled lahars, probably created from newly erupted materials melting snow and glacial ice. The most recent magmatic eruption of Mount Rainier, documented geochemically, was the 1,000 cal year BP event. Products from a proposed eruption of Mount Rainier between AD 1820 and 1854 (X tephra of Mullineaux (US Geol Surv Bull 1326:1–83, 1974)) are redeposited C tephra, probably transported onto young moraines by snow avalanches, and do not record a nineteenth century eruption. We found no conclusive evidence for an eruption associated with the clay-rich Electron Mudflow of ∼500 cal year BP, and though rare, non-eruptive collapse of unstable edifice flanks remains as a potential hazard from Mount Rainier.

  8. Catastrophic eruptions of the directed-blast type at Mount St. Helens, bezymianny and Shiveluch volcanoes

    USGS Publications Warehouse

    Bogoyavlenskaya, G.E.; Braitseva, O.A.; Melekestsev, I.V.; Kiriyanov, V. Yu; Dan, Miller C.

    1985-01-01

    This paper describes catastrophic eruptions of Mount St. Helens (1980), Bezymianny (1955-1956), and Shiveluch (1964) volcanoes. A detailed description of eruption stages and their products, as well as the quantitative characteristics of the eruptive process are given. The eruptions under study belong to the directed-blast type. This type is characterized by the catastrophic character of the climatic stage during which a directed blast, accompanied by edifice destruction, the profound ejection of juvenile pyroclastics and the formation of pyroclastic flows, occur. The climatic stage of all three eruptions has similar characteristics, such as duration, kinetic energy of blast (1017-1018 J), the initial velocity of debris ejection, morphology and size of newly-formed craters. But there are also certain differences. At Mount St. Helens the directed blast was preceeded by failure of the edifice and these events produced separable deposits, namely debris avalanche and directed blast deposits which are composed of different materials and have different volumes, thickness and distribution. At Bezymianny, failure did not precede the blast and the whole mass of debris of the old edifice was outburst only by blast. The resulting deposits, represented by the directed blast agglomerate and sand facies, have characteristics of both the debris avalanche and the blast deposit at Mount St. Helens. At Shiveluch directed-blast deposits are represented only by the directed-blast agglomerate; the directed-blast sand facies, or blast proper, seen at Mount St. Helens is absent. During the period of Plinian activity, the total volumes of juvenile material erupted at Mount St. Helens and at Besymianny were roughly comparable and exceeded the volume of juvenile material erupted at Shiveluch, However, the volume of pyroclastic-flow deposits erupted at Mount St. Helens was much less. The heat energy of all three eruptions is comparable: 1.3 ?? 1018, 3.8-4.8 ?? 1018 and 1 ?? 1017 J for

  9. Atmospheric Effects and Potential Climatic Impact of the 1980 Eruptions of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Deepak, A. (Editor)

    1982-01-01

    Measurements and studies of the 1980 Mount St. Helens volcanic eruptions and their atmospheric effects and climatic impact are addressed. Specific areas discussed include: (1) nature and impact of volcanic eruptions; (2) in situ measurements of effluents; (3) remote sensing measurements; (4) transport and dispersion of volcanic effluents; (5) chemistry of volcanic effluents; and (6) weather and potential climate impact.

  10. Mount st. Helens eruption of 18 may 1980: air waves and explosive yield.

    PubMed

    Donn, W L; Balachandran, N K

    1981-07-31

    Strong atmospheric acoustic-gravity waves were recorded by sensitive microbarographs and seismographs at large distances from the Mount St. Helens eruption of 18 May 1980. Wave signatures were similar to those of waves from large nuclear explosions. Independent theoretical and empirical analyses indicate that the explosive yield of the eruption was approximately 35 megatons.

  11. Carbonyl sulfide and carbon disulfide from the eruptions of mount st. Helens.

    PubMed

    Rasmussen, R A; Khalil, M A; Dalluge, R W; Penkett, S A; Jones, B

    1982-02-05

    Ash from the massive 18 May 1980 eruption of Mount St. Helens readily gave off large amounts of carbonyl sulfide and carbon disulfide gases at room temperature. These findings suggest that the sulfur that enhances the Junge sulfate layer in the stratosphere after volcanic eruptions could be carried directly to the upper atmosphere as carbonyl sulfide and carbon disulfide adsorbed on ash particles from major volcanic eruptions.

  12. Ecological responses to the 1980 eruptions of Mount St. Helens: forward and preface.

    Treesearch

    Virginia H. Dale; Frederick J. Swanson; Charles M. Crisafulli

    2005-01-01

    When Mount St. Helens erupted on May 18, 1980, it did more than just reconfigure a large piece of Cascadian landscape. It also led to dramatic revisions in our perspectives on disturbances, secondary succession, and forestry practices. The Mount St. Helens landscape turned out to be a far more complex place than the "moonscape" that it initially appeared to...

  13. Diversion of lava during the 1983 eruption of Mount Etna.

    USGS Publications Warehouse

    Lockwood, J.P.; Romano, R.

    1985-01-01

    Explosives and earth barriers were used fairly successfully to divert major flows during the 1983 eruption of Etna. Discusses the case history and draws attention to this method as a serious technique in natural hazard prevention. -after Authors

  14. The Atmospheric Impact of the 1991 Mount Pinatubo Eruption

    NASA Technical Reports Server (NTRS)

    Self, Stephen; Zhao, Jing-Xia; Holasek, Rick E.; Torres, Ronnie C.; King, Alan J.

    1993-01-01

    The 1991 eruption of Pinatubo produced about 5 cubic kilometers of dacitic magma and may be the second largest volcanic eruption of the century. Eruption columns reached 40 kilometers in altitude and emplaced a giant umbrella cloud in the middle to lower stratosphere that injected about 17 megatons of SO2, slightly more than twice the largest yielded by the 1982 eruption of El Chichon, Mexico. The SO2 formed sulfate aerosols that produced the largest perturbation to the stratospheric aerosol layer since the eruption of Krakatau in 1883. The aerosol cloud spread rapidly around the Earth in about 3 weeks and attained global coverage by about 1 year after the eruption. Peak local midvisible optical depths of up to 0.4 were measured in late 1992, and globally averaged values were about 0.1 to 0.15 for 2 years. The large aerosol cloud caused dramatic decreases in the amount of net radiation reaching the Earth's surface, producing a climate forcing that was two times stronger than the aerosols of El Chichon. Effects on climate were an observed surface cooling in the northern hemisphere of up to 0.5 to 0.6 C, equivalent to a hemispheric-wide reduction in net radiation of 4 watts per square meter and a cooling of perhaps as large as -0.4 C over large parts of the earth in 1992-93. Climate models seem to have predicted the cooling with a reasonable degree of accuracy. The Pinatubo climate forcing was stronger than the opposite warming of either the El Nino event or anthropogenic greenhouse gases in the period 1991-93. As a result of the presence of the aerosol particles, midlatitude ozone concentrations reached their lowest levels on record during 1992-93, the southern hemisphere 'ozone hole' increased in 1992 to an unprecedented size and ozone depletion rates were observed to be faster than ever before recorded. The atmospheric impact of the Pinatubo eruption has been profound, and it has sparked a lively interest in the role that volcanic aerosols play in climate change

  15. Diversion of lava during the 1983 eruption of Mount Etna

    USGS Publications Warehouse

    Lockwood, J.P.; Romano, R.

    1985-01-01

    During the 1983 eruption of Etna, Italian scientists managed, for the first time, to convince government authorities that direct intervention in natural volcanic processes was warranted. Both explosives and earthen barriers were used to divert major flows. These efforts were fairly successful, although at the time the historic importance of the operations was not fully recognized. 

  16. Olympiodorus's eruption of Mount Etna: A possible date of A.D. 417

    NASA Astrophysics Data System (ADS)

    Uchrin, Gregory

    The list of historic volcanic eruptions in the Mediterranean dating from roughly 1500 B.C. to A.D. 626 of Stothers and Rampino [1983a] is of great usefulness, not only to scientists, but to historians researching the antique and late antique periods. One of the more recent eruptions in the survey is only approximately dated, that of Mount Etna placed sometime within the period 417-425 (this and all remaining dates in this article are A.D.).The reason for the approximate nature of this dating was that the only known reference to the eruption at the time of the survey was a fragment of Olympiodorus's History quoted by Photius. The fragment alludes to an eruption of Mount Etna following the destruction of a pagan guardian statue by the Christian steward of the Sicilian estates of Placidia and Constantius [Gordon, 1961, p. 35].

  17. Paleomagnetic Evidence on a Volcanological Mystery - The 1631 Eruption of Mount Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Conte, G.; Urrutia-Fucugauchi, J.; Gogichaishvili, A.; Incoronato, A.

    2004-12-01

    Was or was not effusive activity part of the 1631 eruption of Mount Vesuvius? We report on a detailed rock magnetic, paleomagnetic and absolute paleointensity study of lava flows from Mount Vesuvius and on its evidence concerning the enigmatic 1631 eruptive episode. Characteristic magnetization directions determined from detailed stepwise alternating field and thermal demagnetization give four new well-defined flow unit mean directions with a95 ranging from 0.7° to 2.4°. Paleodirections for eight lava flows from twenty-two flows studied appear related to the 1631 eruption, as indicated by their correlation to the early seventeen century segment of the Italian paleosecular variation reference curve. This provides new evidence supporting that the 1631 episode was an explosive-effusive eruption.

  18. Eruption-triggered avalanche, flood, and lahar at Mount St. Helens - Effects of winter snowpack

    USGS Publications Warehouse

    Waitt, R.B.; Pierson, T.C.; MacLeod, N.S.; Janda, R.J.; Voight, B.; Holcomb, R.T.

    1983-01-01

    An explosive eruption of Mount St. Helens on 19 March 1982 had substantial impact beyond the vent because hot eruption products interacted with a thick snowpack. A blast of hot pumice, dome rocks, and gas dislodged crater-wall snow that avalanched through the crater and down the north flank. Snow in the crater swiftly melted to form a transient lake, from which a destructive flood and lahar swept down the north flank and the North Fork Toutle River.

  19. Chaos and stochasticity in volcanic eruptions the case of Mount Etna and Vesuvius

    NASA Astrophysics Data System (ADS)

    Marzocchi, Warner

    1996-03-01

    The series of historical eruptions of Mount Etna and Vesuvius volcanoes are analyzed to verify the presence of low-dimensional chaos in the mechanism driving eruptive activity. A recently developed optimal methodology which is efficient on relatively small sets of data is used. The results indicate that there is no evidence of low-dimensional chaos in the sequences considered, and the mechanism appears better described by a classical stationary stochastic process.

  20. Eruption-triggered avalanche, flood, and lahar at mount st. Helens--effects of winter snowpack.

    PubMed

    Waitt, R B; Pierson, T C; Macleod, N S; Janda, R J; Voight, B; Holcomb, R T

    1983-09-30

    An explosive eruption of Mount St. Helens on 19 March 1982 had substantial impact beyond the vent because hot eruption products interacted with a thick snowpack. A blast of hot pumice, dome rocks, and gas dislodged crater-wall snow that avalanched through the crater and down the north flank. Snow in the crater swiftly melted to form a transient lake, from which a destructive flood and lahar swept down the north flank and the North Fork Toutle River.

  1. Size distributions and mineralogy of ash particles in the stratosphere from eruptions of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Farlow, N. H.; Oberbeck, V. R.; Snetsinger, K. G.; Ferry, G. V.; Polkowski, G.; Hayes, D. M.

    1981-01-01

    Samples from the stratosphere obtained by U-2 aircraft after the first three major eruptions of Mount St. Helens contained large globules of liquid acid and ash. Because of their large size, these globules had disappeared from the lower stratosphere by late June 1980, leaving behind only smaller acid droplets. Particle size distributions and mineralogy of the stratospheric ash grains demonstrate inhomogeneity in the eruption clouds.

  2. Size distributions and mineralogy of ash particles in the stratosphere from eruptions of mount st. Helens.

    PubMed

    Farlow, N H; Oberbeck, V R; Snetsinger, K G; Ferry, G V; Polkowski, G; Hayes, D M

    1981-02-20

    Samples from the stratosphere obtained by U-2 aircraft after the first three major eruptions of Mount St. Helens contained large globules of liquid acid and ash. Because of their large size, these globules had disappeared from the lower stratosphere by late June 1980, leaving behind only smaller acid droplets. Particle-size distributions and mineralogy of the stratospheric ash grains demonstrate in-homogeneity in the eruption clouds.

  3. Mount st. Helens, washington, 1980 volcanic eruption: magmatic gas component during the first 16 days.

    PubMed

    Stoiber, R E; Williams, S N; Malinconico, L L

    1980-06-13

    Eruption plumes of Mount St. Helens, Washington, showed low rates of sulfur dioxide emission, and ash leachates had low ratios of sulfur to chlorine. These data and the nonvesicularity of ash fragments are indicative of only a small eruptive magmatic component. The low amounts of soluble fluorine on the ashes pose no health problems. Violent magmatic activity is possible, and thus continued geochemical monitoring is advised.

  4. Model for determining logistic distribution center: case study of Mount Merapi eruption disaster

    NASA Astrophysics Data System (ADS)

    Ai, T. J.; Wigati, S. S.

    2017-01-01

    As one of the most active volcano in the earth, Mount Merapi is periodically erupted and it is considered as a natural disaster for the surrounding area. Kabupaten Sleman as one of the nearest location to this mount has to be always prepared to this disaster. The local government already set three different groups of region, in which potentially affected by Mount Merapi eruption, called KRB I, KRB II, and KRB III. Region KRB III is the closest area to the mount crater and most often affected by the eruption disaster. Whenever KRB III is affected, people live in that area usually being transfer to the next region set that is KRB II. The case presented in this paper is located at the KRB II region, which is the second closest region to the mount crater. A humanitarian distribution system has to be set in this region, since usually this region is became the location of shelters for KRB III population whenever a ‘big’ eruption is happened. A mathematical model is proposed in this paper, for determining the location of distribution center, vehicle route, and the amount of goods delivered to each customer. Some numerical illustration are presented in order to know the behavior of the proposed model.

  5. Predicting eruptions at Mount St. Helens, June 1980 through December 1982

    USGS Publications Warehouse

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

    1983-01-01

    Thirteen eruptions of Mount St. Helens between June 1980 and December 1982 were predicted tens of minutes to, more generally, a few hours in advance. The last seven of these eruptions, starting with that of mid-April 1981, were predicted between 3 days and 3 weeks in advance. Precursory seismicity, deformation of the crater floor and the lava dome, and, to a lesser extent, gas emissions provided telltale evidence of forthcoming eruptions. The newly developed capability for prediction reduced risk to life and property and influenced land-use decisions.

  6. Measurements of the stratospheric plume from the mount st. Helens eruption: radioactivity and chemical composition.

    PubMed

    Leifer, R; Hinchliffe, L; Fisenne, I; Franklin, H; Knutson, E; Olden, M; Sedlacek, W; Mroz, E; Cahill, T

    1981-11-20

    Gas measurements made in the stratospheric plume from the eruption of Mount St. Helens on 18 May 1980 were not consistent with a reported large injection of radon-222 into the atmosphere. No enrichment in the volatile element polonium was found in filter samples, and the ratio of polonium-210 to lead-210 was not different from background values. Data obtained with an experimental impactor, flown shortly after the eruption, showed an increase of 10(3) in the stratospheric number concentration of submicrometer sulfate particles compared to concentrations before the eruption.

  7. Predicting eruptions at mount st. Helens, june 1980 through december 1982.

    PubMed

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

    1983-09-30

    Thirteen eruptions of Mount St. Helens between June 1980 and December 1982 were predicted tens of minutes to, more generally, a few hours in advance. The last seven of these eruptions, starting with that of mid-April 1981, were predicted between 3 days and 3 weeks in advance. Precursory seismicity, deformation of the crater floor and the lava dome, and, to a lesser extent, gas emissions provided telltale evidence of forthcoming eruptions. The newly developed capability for prediction reduced risk to life and property and influenced land-use decisions.

  8. Magma mixing during the 2001 event at Mount Etna (Italy): Effects on the eruptive dynamics

    NASA Astrophysics Data System (ADS)

    Viccaro, M.; Ferlito, C.; Cortesogno, L.; Cristofolini, R.; Gaggero, L.

    2006-01-01

    During the 2001 eruptive episode three different magmas were erupted on the southern flank of Mount Etna volcano from distinct vent systems. Major and minor element chemistry of rocks and minerals shows that mixing occurred, and that the mixed magma was erupted during the last eruptive phases. The space-time integrated analysis of the eruption, supported by geophysical data, together with major and trace element bulk chemistry (XRF, ICP-MS) and major and trace mineral chemistry (EPMA, LAM ICP-MS), support the following model: 1) trachybasaltic magma rises through a NNW-SSE trending structure, connected to the main open conduit system; 2) ascent of an amphibole-bearing trachybasaltic magma from a 6 km deep eccentric reservoir through newly open N-S trending fractures; 3) just a few days following the eruption onset the two tectonic systems intersect at the Laghetto area; 4) at the Laghetto vent a mixed magma is erupted. Mixing occurred between the amphibole-bearing trachybasaltic magma and an inferred deep more basic end-member. The most relevant aspect in the eruptive dynamics is that the eruption of the mixed magma at the Laghetto vent was highly explosive due to volatile content in the magma. The gas phase formed, mainly because of the decreased volatile solubility due to rapid fractures opening and increased T, related to mixing, and partially because of the amphibole breakdown.

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

    USGS Publications Warehouse

    Gardner, C.

    2005-01-01

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

  10. Global Temperature Response to the Major Volcanic Eruptions in Multiple Reanalysis Datasets

    NASA Astrophysics Data System (ADS)

    Fujiwara, M.; Hibino, T.; Mehta, S. K.; Gray, L. J.; Mitchell, D.; Anstey, J.

    2015-12-01

    Global temperature response to the eruptions of Mount Agung in 1963, El Chichón in 1982 and Mount Pinatubo in 1991 is investigated using nine reanalysis datasets (JRA-55, MERRA, ERA-Interim, NCEP-CFSR, JRA-25, ERA-40, NCEP-1, NCEP-2, and 20CR). Multiple linear regression is applied to the zonal and monthly mean time series of temperature for two periods, 1979-2009 (for eight reanalysis datasets) and 1958-2001 (for four reanalysis datasets), by considering explanatory factors of seasonal harmonics, linear trends, Quasi-Biennial Oscillation, solar cycle, and El Niño Southern Oscillation. The residuals are used to define the volcanic signals for the three eruptions separately. In response to the Mount Pinatubo eruption, most reanalysis datasets show strong warming signals (up to 2-3 K for one-year average) in the tropical lower stratosphere and weak cooling signals (down to -1 K) in the subtropical upper troposphere. For the El Chichón eruption, warming signals in the tropical lower stratosphere are somewhat smaller than those for the Mount Pinatubo eruption. The response to the Mount Agung eruption is asymmetric about the equator with strong warming in the Southern Hemisphere midlatitude upper troposphere to lower stratosphere. Comparison of the results from several different reanalysis datasets confirms the atmospheric temperature response to these major eruptions qualitatively, but also shows quantitative differences even among the most recent reanalysis datasets.

  11. Acoustic source characterization of impulsive Strombolian eruptions from the Mount Erebus lava lake

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey; Aster, Richard; Jones, Kyle R.; Kyle, Philip; McIntosh, Bill

    2008-11-01

    We invert for acoustic source volume outflux and momentum imparted to the atmosphere using an infrasonic network distributed about the erupting lava lake at Mount Erebus, Ross Island, Antarctica. By modeling these relatively simple eruptions as monopole point sources we estimate explosively ejected gas volumes that range from 1,000 m 3 to 24,000 m 3 for 312 lava lake eruptions recorded between January 6 and April 13, 2006. Though these volumes are compatible with bubble volumes at rupture (as estimated from explosion video records), departures from isotropic radiation are evident in the recorded acoustic wavefield for many eruptions. A point-source acoustic dipole component with arbitrary axis orientation and strength provides precise fit to the recorded infrasound. This dipole source axis, corresponding to the axis of inferred short-duration material jetting, varies significantly between events. Physical interpretation of dipole orientation as being indicative of eruptive directivity is corroborated by directional emissions of ejecta observed in Erebus eruption video footage. Although three azimuthally distributed stations are insufficient to fully characterize the eruptive acoustic source we speculate that a monopole with a minor amount of oriented dipole radiation may reasonably model the primary features of the recorded infrasound for these eruptions.

  12. The 19 March 1982 Eruption and Lahar at Mount Saint Helens: Implications for Martian Outlfow Channels?

    NASA Technical Reports Server (NTRS)

    Beach, G. L.

    1984-01-01

    A small explosive eruption of Mount St. Helens set into motion an unusually complex series of geomorphic and hydrologic processes that had not previously been described in the literature. This event was unusual in that a laterally-directed eruption dislodged and mobilized a thick snowpack from the surrounding crater floor and walls, resulting in the formation of a temporary lake. Catastrophic release of this self-impounded lake spawned a series of destructive debris avalanches and debris flows that moved rapidly down the volcano's north flank and into the North Toutle River valley. Catastrophic release of volatiles mobilized by volcanic activity has been discussed as a possible mechanism to explain a class of outflow channels on Mars. The eruption of Mount St. Helens provides a unique opportunity to study the deposits and landforms created by such an event; a more detailed field study and examination of Viking photographs of martian outflow channels is underway.

  13. The 19 March 1982 eruption and lahar at Mount Saint Helens: Implications for Martian outlfow channels?

    NASA Astrophysics Data System (ADS)

    Beach, G. L.

    1984-04-01

    A small explosive eruption of Mount St. Helens set into motion an unusually complex series of geomorphic and hydrologic processes that had not previously been described in the literature. This event was unusual in that a laterally-directed eruption dislodged and mobilized a thick snowpack from the surrounding crater floor and walls, resulting in the formation of a temporary lake. Catastrophic release of this self-impounded lake spawned a series of destructive debris avalanches and debris flows that moved rapidly down the volcano's north flank and into the North Toutle River valley. Catastrophic release of volatiles mobilized by volcanic activity has been discussed as a possible mechanism to explain a class of outflow channels on Mars. The eruption of Mount St. Helens provides a unique opportunity to study the deposits and landforms created by such an event; a more detailed field study and examination of Viking photographs of martian outflow channels is underway.

  14. Geologic Map of Mount St. Helens, Washington Prior to the 1980 Eruption

    USGS Publications Warehouse

    Hopson, Clifford A.

    2008-01-01

    It is rare that a geologic map exists for a volcano prior to such a catastrophic modification as that produced by the eruption of Mount St. Helens in 1980. As such, this map provides an important historical record of the volcano prior to that eruption. The map has not been reviewed or checked for conformity to USGS editorial standards or stratigraphic nomenclature, and it has not been digitized. This version of the map is unchanged from that submitted to the USGS for publication shortly after the 1980 eruption of Mount St. Helens and includes unresolved inconsistencies with the subsequently published work of Crandell (1987) and Mullineaux (1996). Nevertheless, it is the most accurate available depiction of the pre-1980 edifice and is published here for comparison with more recent geologic mapping and historical perspectives.

  15. Magmatic vapor source for sulfur dioxide released during volcanic eruptions: Evidence from Mount Pinatubo

    USGS Publications Warehouse

    Wallace, P.J.; Gerlach, T.M.

    1994-01-01

    Sulfur dioxide (SO2) released by the explosive eruption of Mount Pinatubo on 15 June 1991 had an impact on climate and stratospheric ozone. The total mass of SO2 released was much greater than the amount dissolved in the magma before the eruption, and thus an additional source for the excess SO2 is required. Infrared spectroscopic analyses of dissolved water and carbon dioxide in glass inclusions from quartz phenocrysts demonstrate that before eruption the magma contained a separate, SO2-bearing vapor phase. Data for gas emissions from other volcanoes in subduction-related arcs suggest that preeruptive magmatic vapor is a major source of the SO2 that is released during many volcanic eruptions.

  16. Monitoring the 1980-1982 eruptions of mount st. Helens: compositions and abundances of glass.

    PubMed

    Melson, W G

    1983-09-30

    The Mount St. Helens eruptive sequence of 1980 through 1982 reflects the tapping of successively less water-rich, more highly crystallized, and more viscous, highly phyric dacitic magmas. These changes reflect both syn- and preeruption processes. The decreasing water content points to a continued decline in the volume and intensity of explosive pyroclastic activity. This decreasing water content appears to be composed of a long-term trend established during a long period of repose (about 130 years) imposed on short-term trends established during short periods (about 7 to 100 days) of repose between eruptions in the present eruptive cycle. The last two eruptive cycles of this volcano, the T (A.D. 1800) and W cycles (about A. D. 1500), exhibited similar trends. These changes are inferred from a combination of petrographic, bulk chemical, and electron- and ion-microprobe analyses of matrix and melt-inclusion glasses.

  17. The 18 May 1980 eruption of Mount St. Helens: The nature of the eruption, with an atmospheric perspective

    NASA Technical Reports Server (NTRS)

    Rose, W. I., Jr.; Hoffman, M. F.

    1982-01-01

    Mount St. Helens erupted somewhat less than 0.5 cu km of magma (dense rock equivalent) on May 18, 1980. The May 18 event was usually violent. As much 35% of the volume of the airfall material fell outside of the 2.5 mm isopach, which encloses about 88,000 sq km. This extraordinary dispersive power was transmitted by an eruption column which reached heights of more than 20 km. There was a lateral blast (or surge) of unusually large dimensions associated with the onset of the eruption. The magma is dacitic in composition and had a low ( 500 ppm) sulfur content. Distal ashes contain much nonmagmatic (lithic) material, but smaller ( 50 microns m) particles are mostly finely divided magmatic dacite. The grain size distributions of the ash are multimodal, frequently with peaks at 90, 25, and 10 microns. The finer populations fell out faster than their terminal velocities as simple particles would suggest. It is inferred that large proportions of the fine ash fell out as composite particles. This condition greatly reduces the atmospheric burden of silicate particles. Some of the unusual aspects (violence, intense surges, multimodal grain size distributions, lithic content of the ashes) of the eruption may be due to its phreatomagmatic character. The hydrothermal system above the magma may have infiltrated the magma body at the onset of the eruption. An "overprint" of the geochemistry of this hydrothermal system on the geochemistry of the magmatic gas system is likely. One important feature is that reduced gas species may be much more abundant than in many eruptions. Another is that fine ash may form aggregates more readily.

  18. Evaluation of mental effects of disaster, Mount St. Helens eruption.

    PubMed

    Shore, J H; Tatum, E L; Vollmer, W M

    1986-03-01

    This psychiatric epidemiology study following the Mount St. Helens volcanic disaster revealed a significant morbidity for psychiatric disorders. The increased prevalence showed a dose response pattern in three population groups. The findings are reported as relative and attributable risk for the two exposed populations as compared to a control group. Patterns of significant risk are presented for sex, age, and for victims with pre-existing physical illness. The research utilized a new criteria-based interview schedule for the identification of psychiatric disorders. The methodology is reviewed in the context of the controversies and assumptions within the field of behavioral response to disaster stress. There are important implications for public health planning and intervention.

  19. Evaluation of mental effects of disaster, Mount St. Helens eruption.

    PubMed Central

    Shore, J H; Tatum, E L; Vollmer, W M

    1986-01-01

    This psychiatric epidemiology study following the Mount St. Helens volcanic disaster revealed a significant morbidity for psychiatric disorders. The increased prevalence showed a dose response pattern in three population groups. The findings are reported as relative and attributable risk for the two exposed populations as compared to a control group. Patterns of significant risk are presented for sex, age, and for victims with pre-existing physical illness. The research utilized a new criteria-based interview schedule for the identification of psychiatric disorders. The methodology is reviewed in the context of the controversies and assumptions within the field of behavioral response to disaster stress. There are important implications for public health planning and intervention. PMID:3946730

  20. Deposition and dose from the 18 May 1980 eruption of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Peterson, K. R.

    1982-01-01

    The downwind deposition and radiation doses was calculated for the tropospheric part of the ash cloud from the May 18, 1980 eruption of Mount St. Helens, by using a large cloud diffusion model. The naturally occurring radionnuclides of radium and thorium, whose radon daughters normally seep very slowly from the rocks and soil, were violently released to the atmosphere. The largest dose to an individual from these nuclides is small, but the population dose to those affected by the radioactivity in the ash is about 100 person rem. This population dose from Mount St. Helens is much greater than the annual person rem routinely released by a typical large nuclear power plant. It is estimated that subsequent eruptions of Mount St. Helens have doubled or tripled the person rem calculated from the initial large eruption. The long range global ash deposition of the May 18 eruption is estimated through 1984, by use of a global deposition model. The maximum deposition is nearly 1000 kg square km and occurs in the spring of 1981 over middle latitudes of the Northern Hemisphere.

  1. Global tracking of the SO2 clouds from the June, 1991 Mount Pinatubo eruptions

    NASA Technical Reports Server (NTRS)

    Bluth, Gregg J. S.; Doiron, Scott D.; Schnetzler, Charles C.; Krueger, Arlin J.; Walter, Louis S.

    1992-01-01

    The explosive June 1991 eruptions of Mount Pinatubo produced the largest sulfur dioxide cloud detected by the Total Ozone Mapping Spectrometer (TOMS) during its 13 years of operation: approximately 20 million tons of SO2, predominantly from the cataclysmic June 15th eruption. The SO2 cloud observed by the TOMS encircled the earth in about 22 days (about 21 m/s); however, during the first three days the leading edge of the SO2 cloud moved with a speed that averaged about 35 m/s. Compared to the 1982 El Chichon eruptions, Pinatubo outgassed nearly three times the amount of SO2 during its explosive phases. The main cloud straddled the equator within the first two weeks of eruption, whereas the El Chichon cloud remained primarily in the Northern Hemisphere. The measurements indicate that Mount Pinatubo has produced a much larger and perhaps longer-lasting SO2 cloud; thus, climatic responses to the Pinatubo eruption can exceed those of El Chichon.

  2. Impact on agriculture of the mount st. Helens eruptions.

    PubMed

    Cook, R J; Barron, J C; Papendick, R I; Williams, G J

    1981-01-02

    Ash from Mount St. Helens has fallen over a diverse agricultural area, with deposits of up to 30 kilograms per square meter. Crop losses in eastern Washington are estimated at about $100 million in 1980-about 7 percent of the normal crop value in the affected area and less than was expected initially. Production of wheat, potatoes, and apples will be normal or above normal because the favorable conditions for growth of these crops since the ashfall helped offset the losses. Alfalfa hay was severely lodged under the weight of the ash, but ash-contaminated hay is apparently nontoxic when eaten by livestock. The ash as an abrasive is lethal to certain insects, such as bees and grasshoppers, but populations are recovering. The ash has increased crop production costs by necessitating machinery repairs and increased tillage. On soil, the ash reduces water infiltration, increases surface albedo, and may continue to affect water runoff, erosion, evaporation, and soil temperature even when tilled into the soil. Ash on plant leaves reduced photosynthesis by up to 90 percent. Most plants have tended to shed the ash. With the possible exception of sulfur, the elements in the ash are either unavailable or present in very low concentrations; and no significant contribution to the nutrient status of soils is expected.

  3. Problems in the climatology of the 1980 Mount St. Helens eruptions. [surface heat and water budgets

    NASA Technical Reports Server (NTRS)

    Critchfield, H. J.

    1982-01-01

    A brief review of the effects of climate and weather on the 1980 Mount St. Helens eruptions and the subsequent dispersion of ash and gases and the reciprocal influences of the eruptions on climate and climatology is presented. The effects of mesoscale destruction of snow fields and vegetation, a revised mountain profile, and ash deposits are addressed along with impacts on hemispheric climate and disruption of normal climatological observations, in the areas directly affected by the explosions and ashfall. Environmental and economic consequences are also considered.

  4. 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.

  5. Airborne studies of the emissions from the volcanic eruptions of mount st. Helens.

    PubMed

    Hobbs, P V; Radke, L F; Eltgroth, M W; Hegg, D A

    1981-02-20

    The concentrations of particles less than 10 micrometers in diameter in the ash emissions from Mount St. Helens have been more than 1000 times greater than those in the ambient air. Mass loadings of particles less than 2 micrometers in diameter were generally several hundred micrograms per cubic meter. In the ash clouds, produced by the large eruption on 18 May 1980, the concentrations of several trace gases generally were low. In other emissions, significant, but variable, concentrations of sulfur gases were measured. The 18 May eruption produced nuées ardentes, lightning flashes, and volcanic hail.

  6. Characterization of organic contaminants in environmental samples associated with mount St. Helens 1980 volcanic eruption

    USGS Publications Warehouse

    Pereira, W.E.

    1982-01-01

    Volcanic ash, surface-water, and bottom-material samples obtained in the vicinity of Mount St. Helens after the May 18, 1980, eruption were analyzed for organic contaminants by using capillary gas chromatography-mass spectrometry-computer techniques. Classes of compounds identified include n-alkanes, fatty acids, dicarboxylic acids, aromatic acids and aldehydes, phenols, resin acids, terpenes, and insect juvenile hormones. The most probable source of these compounds is from pyrolysis of plant and soil organic matter during and after the eruption. The toxicity of selected compounds and their environmental significance are discussed.

  7. Dense Juvenile Clasts as Evidence for Pre-eruptive Magmatic Degassing - a Re-examination of Eruptive Precursors to the May 18, 1980 Eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.; Hoblitt, R. P.

    2002-05-01

    Evidence of volatile exsolution and escape from magma ascending within volcanic conduits comes not only from measurement of diffuse gas emissions from volcanoes, but also from dense, partially degassed juvenile clasts in pyroclastic deposits. Volatiles preserved in the matrix glass of dense clasts have been used to infer changes in the fragmentation level during subplinian eruptions [Newman et al., 1988] and the location of magma storage before eruptive events [Hoblitt and Harmon, 1993], while crystals forming in response to degassing indicate time scales of shallow storage [Hammer et al., 1999]. Such clasts have not yet been exploited for monitoring purposes, although they may hold important clues to the progress of magma ascent and degassing prior to magmatic eruptions. We illustrate this potential by re-examining lithic clasts erupted during precursory activity at Mount St. Helens in March and April of 1980. The May 18, 1980 eruption of Mount St. Helens provides an unusual case study of degassing and crystallization during pre-eruptive magma ascent. The cryptodome that intruded during the two months prior to the climactic eruption has been extensively sampled and characterized, and thus provides a baseline for identification of juvenile magma in precursory ash. Cryptodome intrusion was heralded by the abrupt onset of seismicity in later March, 1980, and was accompanied by episodic harmonic tremor and energetic emissions of steam and ash, particularly during the first few weeks of April. These precursory eruptions were low in SO2, and were inferred to be phreatic (non-magmatic), with fragmental material derived from the pre-existing volcanic edifice [Christiansen and Peterson, 1980]. Microscopic examination of the material apparently confirmed this hypothesis, as ejected material formed a crystal-lithic tephra layer that contained no pumice or glassy ash shards [Sarna-Wojcicki et al., 1980]. However, a dense clast collected from the volcano's flanks in April

  8. Vapor transfer prior to the October 2004 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Kent, A.J.R.; Blundy, J.; Cashman, K.V.; Copper, K.M.; Donnelly, C.; Pallister, J.S.; Reagan, M.; Rowe, M.C.; Thornber, C.R.

    2007-01-01

    Dome lavas from the 2004 eruption of Mount St. Helens show elevated Li contents in plagioclase phenocrysts at the onset of dome growth in October 2004. These cannot be explained by variations in plagioclase-melt partitioning, but require elevated Li contents in coexisting melt, a fact confirmed by measurements of Li contents as high as 207 ??g/g in coexisting melt inclusions. Similar Li enrichment has been observed in material erupted prior to and during the climactic May 1980 eruption, and is likewise best explained via pre-eruptive transfer of an exsolved alkali-rich vapor phase derived from deeper within the magma transport system. Unlike 1980, however, high Li samples from 2004 show no evidence of excess (210Pb)/(226 Ra), implying that measurable Li enrichments may occur despite significant differences in the timing and/or extent of magmatic degassing. Diffusion modeling shows that Li enrichment occurred within -1 yr before eruption, and that magma remained Li enriched until immediately before eruption and cooling. This short flux time and the very high Li contents in ash produced by phreatomagmatic activity prior to the onset of dome extrusion suggest that vapor transfer and accumulation were associated with initiation of the current eruption. Overall, observation of a high Li signature in both 1980 and 2004 dacites indicates that Li enrichment may be a relatively common phenomenon, and may prove useful for petrologic monitoring of Mount St. Helens and other silicic volcanoes. Lithium diffusion is also sufficiently rapid to constrain vapor transfer on similar time scales to short-lived radionuclides. ?? 2007 Geological Society of America.

  9. Pyroclastic deposits of the Mount Edgecumbe volcanic field, southeast Alaska: eruptions of a stratified magma chamber

    USGS Publications Warehouse

    Riehle, J.R.; Champion, D.E.; Brew, D.A.; Lanphere, M.A.

    1992-01-01

    The Mount Edgecumbe volcanic field in southeastern Alaska consists of 5-6 km3 (DRE) of postglacial pyroclasts that overlie Pleistocene lavas. All eleven pyroclast vents align with the long axis of the field, implying that the pyroclast magma conduits followed a crustal fissure. Most of these vents had previously erupted lavas that are compositionally similar to the pyroclasts, so a persistent magma system (chamber) had likely evolved by the onset of the pyroclastic eruptions. The pyroclastic sequence was deposited in about a millennium and is remarkable for a wide range of upward-increasing silica contents (51-72% SiO2), which is consistent with rise of coexisting magmas at different rates governed by their viscosity. Basaltic and andesitic lava flows have erupted throughout the lifetime of the field. Rhyolite erupted late; we infer that it formed early but was hindered from rising by its high viscosity. Most of the magmas-and all siliceous ones-erupted from vents on the central fissure. Basalt has not erupted from the center of the field during at least the latter part of its lifetime. Thus the field may illustrate basalt underplating: heat and mass flux are concentrated at the center of a stratified magma chamber in which a cap of siliceous melt blocks the rise of basalt. Major-element, strontium isotope, and mineral compositions of unaltered pyroclasts are broadly similar to those of older lavas of similar SiO2 content. Slightly fewer phenocrysts, inherited grains, and trace amphibole in pyroclastic magmas may be due simply to faster rise and less undercooling and degassing before eruption relative to the lavas. Dacite occurs only in the youngest deposits; the magma formed by mixing of andesitic and rhyolitic magmas erupted shortly before by the dacitic vents. ?? 1992.

  10. Cessation of the 2004-2008 Dome-Building Eruption at Mount St. Helens, Washington

    NASA Astrophysics Data System (ADS)

    Moran, S. C.; Dzurisin, D.; Lisowski, M.; Schilling, S. P.; Anderson, K. R.; Werner, C. A.

    2015-12-01

    The 2004-2008 dome-building eruption at Mount St. Helens ended during the winter of 2007-2008 at a time when field observations were hampered by persistent bad weather. As a result, recognizing the end of the eruption was challenging. Also challenging was the fact that signs of continued eruption were increasingly subtle — earthquakes were small, deformation signals tiny, gas content close to background — and observing these phenomena was critically dependent on recordings and measurements made close (< 2 km) to the vent. In hindsight, the end of the eruption was presaged by a slight increase in seismicity in December 2007 that culminated on January 12-13, 2008, with a flurry of more than 500 events, most of which occurred in association with several tremor-like signals and a spasmodic burst of long-period earthquakes. At about the same time, a series of regular, localized, small-amplitude tilt events — thousands of which had been recorded during earlier phases of the eruption — came to an end. Thereafter, seismicity declined to 10-20 events per day until January 27-28, when a spasmodic burst of about 50 volcano-tectonic earthquakes occurred over a span of 3 hours. This was followed by a brief return of repetitive "drumbeat" earthquakes that characterized much of the eruption. By January 31, seismicity had declined to 1-2 earthquakes per day, a rate similar to pre-eruption levels. We attribute the tilt and seismic observations to progressive stagnation of an increasingly stiffened plug of magma in the upper part of the conduit. Upward movement of the plug ceased when the excess driving pressure, which had gradually decreased throughout the eruption as a result of reservoir deflation and increasing overburden from the growing dome, was overcome by increasing sidewall friction as a result of cooling and crystallization of the plug.

  11. Seismic precursors to the mount st. Helens eruptions in 1981 and 1982.

    PubMed

    Malone, S D; Boyko, C; Weaver, C S

    1983-09-30

    Six categories of seismic events are recognized on the seismograms from stations in the vicinity of Mount St. Helens. Two types of high-frequency earthquakes occur near the volcano and under the volcano at depths of more than 4 kilometers. Medium- and low-frequency earthquakes occur at shallow depths (less than 3 kilometers) within the volcano and increase in number and size before eruptions. Temporal changes in the energy release of the low-frequency earthquakes have been used in predicting all the eruptions since October 1980. During and after eruptions, two types of low-frequency emergent surface events occur, including rockfalls and steam or gas bursts from the lava dome.

  12. Petrologic monitoring of 1981 and 1982 eruptive products from mount st. Helens.

    PubMed

    Cashman, K V; Taggart, J E

    1983-09-30

    New material from the dacite lava dome of Mount St. Helens, collected soon after the start of each successive extrusion, is subjected to rapid chemical and petrologic analysis. The crystallinity of the dacite lava produced in 1981 and 1982 is 38 to 42 percent, about 10 percent higher than for products of the explosive 1980 eruptions. This increase in crystallinity accompanies a decrease in the ratio of hornblende to hornblende plus orthopyroxene, which suggests that the volatile-rich, crystal-poor material explosively erupted in 1980 came from the top of a zoned magma chamber and that a lower, volatile-poor and crystal-rich region is now being tapped. The major-element chemistry of the dacite lava has remained essentially constant (62 to 63 percent silica) since August 1980, ending a trend of decreasing silica seen in the products of the explosive eruptions of May through August 1980.

  13. Atmospheric oscillations after the May 18, 1980 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Bolt, Bruce A.; Tanimoto, Toshiro

    Air waves corresponding both to direct (A1) and antipodean (A2) travel paths were clearly recorded on a sensitive microbarograph at Berkeley after the violent eruption of Mount St. Helens on May 18, 1980 (see Figure 1). These unusual complementary recordings throw light on the acoustic energy released as compared with Krakatoa [Strachey, 1888], atmospheric oscillations and their attenuation, and the directive properties of the phreatic blast. The principal explosive eruptions followed closely on an earthquake, Richter magnitude 4.9, origin time 1532 GMT, centered near the volcano. Atmospheric waves and associated magnetic perturbations [Fougere and Tsacoyeanes, 1980] from these eruptions were recorded by microbarographs, seismographs, and magnetometers around the world. In particular, Ritsema [1980] has published records of the A1 atmospheric wave train and the A2 wave (called B1 by him) recorded at De Bilt, Holland. The A2 waves at De Bilt, however, are barely visible on the paper record.

  14. The mount st. Helens volcanic eruption of 18 may 1980: minimal climatic effect.

    PubMed

    Robock, A

    1981-06-19

    An energy-balance numerical climate model was used to simulate the effects of the Mount St. Helens volcanic eruption of 18 May 1980. The resulting surface temperature depression is a maximum of 0.1 degrees C in the winter in the polar region, but is an order of magnitude smaller than the observed natural variability from other effects and will therefore be undetectable.

  15. Trace element composition of the mount st. Helens plume: stratospheric samples from the 18 may eruption.

    PubMed

    Vossler, T; Anderson, D L; Aras, N K; Phelan, J M; Zoller, W H

    1981-02-20

    Atmospheric particulate material collected from the stratosphere in the plume of the 18 May 1980 eruption of the Mount St. Helens volcano was quite similar in composition to that of ash that fell to the ground in western Washington. However, there were small but significant differences in concentrations of some elements with altitude, indicating that the stratospheric material was primarily produced from fresh magma, not fragments of the mountain.

  16. Trace element composition of the Mount St. Helens plume - Stratospheric samples from the 18 May eruption

    NASA Technical Reports Server (NTRS)

    Vossler, T.; Anderson, D. L.; Aras, N. K.; Phelan, J. M.; Zoller, W. H.

    1981-01-01

    Atmospheric particulate material collected from the stratosphere in the plume of the 18 May 1980 eruption of the Mount St. Helens volcano was quite similar in composition to that of ash that fell to the ground in western Washington. However, there were small but significant differences in concentrations of some elements with altitude, indicating that the stratospheric material was primarily produced from fresh magma, not fragments of the mountain.

  17. Temporal change in coda wave attenuation observed during an eruption of Mount St. Helens

    SciTech Connect

    Fehler, M.; Roberts, P.; Fairbanks, T.

    1988-05-10

    During the past few years there have been numerous reports of changes in coda wave attenuation occurring before major earthquakes. These observations are important because they may provide insight into stress-related structural changes taking place in the focal region prior to the occurrence of large earthquakes. The results of these studies led us to suspect that temporal changes in coda wave attenuation might also accompany volcanic eruptions. By measuring power decay envelopes for earthquakes at Mount St. Helens recorded before, during, and after an eruption that took place during September 3--6, 1981, we found that coda Q/sup -1/ for frequenciesmore » between 6 and 30 Hz was 20--30% higher before the eruption than after. The change is attributed to an increase in the density of open microcracks in the rock associated with inflation of the volcano prior to the eruption. Q/sup -1/ was found to be only weakly dependent on frequency and displayed a slight peak near 10 Hz. The weak frequency dependence is attributed to the dominance of intrinsic attenuation over scattering attenuation, since it is generally accepted that intrinsic attenuation is constant with frequency, whereas scattering attenuation decreases strongly at higher frequencies. The weak frequency dependence of Q/sup -1/ at Mount St. Helens contrasts with results reported for studies in nonvolcanic regions. The peak in Q/sup -1/ near 10 Hz at Mount St. Helens is attributed to the scale length of heterogeneity responsible for generating backscattered waves. Results for nonvolcanic regions have shown this peak to occur near 0.5 Hz. Thus a smaller scale length of heterogeneity is required to explain the 10-Hz peak at Mount St. Helens. copyright American Geophysical Union 1988« less

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

    USGS Publications Warehouse

    Pallister, John S.; Thornber, Carl R.; Cashman, Katharine V.; Clynne, Michael A.; Lowers, Heather; Mandeville, Charles W.; Brownfield, Isabelle K.; Meeker, Gregory P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

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

  19. Ground Tilt Associated with the 2004-Present Eruption of Mount St. Helens, Washington

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Lisowski, M.; Segall, P.

    2007-12-01

    Tiltmeters in the near-vent region of effusively erupting volcanoes may shed important light on the mechanics of lava extrusion and dome growth. Tiltmeters installed in the crater at Mount St. Helens, Washington, during the ongoing eruption (2004 to present) have recorded cyclic, repeating tilt events throughout the course of the eruption. Individual tilt events last from minutes to hours, are remarkably coherent between different tiltmeters within the crater, and frequently display a clear saw-tooth shaped temporal evolution. Azimuths of the tilt events have remained remarkably consistent over time, and point to a source located generally beneath the south part of the 1980-86 lava dome. Local seismic activity strongly affects the tilt signals, introducing both an instrument response unrelated to real ground tilt, and also in many cases triggering real tilt events that may last for many minutes. Teleseisms are easily detected by the tiltmeters, and have also been observed to trigger longer-period tilt events. It seems likely that ground tilt is related to the motion of (nearly solid) magma as it moves up the conduit at Mount St. Helens, and its diversion to the south beneath the 1980-86 lava dome. While the eruption appears to be steady over longer time scales, the tilt signals require episodic behavior. Inversion of the tilt data for a generalized source should reveal the kinematics of this transient process.

  20. Monitoring eruptive activity at Mount St. Helens with TIR image data

    USGS Publications Warehouse

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

    2005-01-01

    Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre-eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum temperatures of ???330??C and TIR data acquired concurrently from a Forward Looking Infrared (FLIR) camera showed maximum temperatures ???675??C, in narrow (???1-m) fractures of molten rock on a new resurgent dome. MASTER and FLIR thermal flux calculations indicated a radiative cooling rate of ???714 J/m2/S over the new dome, corresponding to a radiant power of ???24 MW. MASTER data indicated the new dome was dacitic in composition, and digital elevation data derived from LIDAR acquired concurrently with MASTER showed that the dome growth correlated with the areas of elevated temperatures. Low SO2 concentrations in the plume combined with sub-optimal viewing conditions prohibited quantitative measurement of plume SO2. The results demonstrate that airborne TIR data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes. Given sufficient resources, the airborne instrumentation could be deployed rapidly to a newly-awakening volcano and provide a means for remote volcano monitoring. Copyright 2005 by the American Geophysical Union.

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  2. Eruptions of Mount Erebus Volcano Constrained with Infrasound, Video, and Doppler Radar

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Jones, K. R.; Aster, R.; Kyle, P.; McIntosh, W.; Gerst, A.

    2008-12-01

    Co-eruptive infrasound recorded within several km of volcanoes can provide effective constraints on atmospheric accelerations or momentum exchange in the vicinity of active volcanic vents. These atmospheric perturbations can be induced by impulsive gas injection into the atmosphere (i.e., eruptive explosions), by deflection of a solid or fluid lava surface, or through a superposition of these effects. The "simple" lava lake bubble-bursting eruptions of Mount Erebus Volcano (Antarctica) provide an ideal test bed for multi- disciplinary observations of volcanic infrasound because of proximal (within few hundred meters) deployment of microphones and line-of-sight viewing geometry of cameras and radar to the vent. Erebus video observations provide timing constraints on the infrasound generation mechanisms, which include both pre- eruptive distension of the lava lake surface and gas expansion and jetting following large explosive bubble bursts. Network infrasound recordings are used to quantify the time history of explosive gas flux and cumulative yield (>103 kg of gas in ~0.5 s), which is corroborated by the video and Doppler radar observations. Infrasound records from a three-station network also show azimuthal variations, which can be attributed to non-isotropic components of the acoustic wavefield radiated during eruption. We model Erebus gas bubble bursts as a combination of symmetric gas expansion (monopole source) and gas jetting (dipole source) and corroborate this explosive asymmetry with video and Doppler radar observations.

  3. The 2004-2008 dome-building eruption at Mount St. Helens, Washington: epilogue

    NASA Astrophysics Data System (ADS)

    Dzurisin, Daniel; Moran, Seth C.; Lisowski, Michael; Schilling, Steve P.; Anderson, Kyle R.; Werner, Cynthia

    2015-10-01

    The 2004-2008 dome-building eruption at Mount St. Helens ended during winter 2007-2008 at a time when field observations were hampered by persistent bad weather. As a result, recognizing the end of the eruption was challenging—but important for scientists trying to understand how and why long-lived eruptions end and for public officials and land managers responsible for hazards mitigation and access restrictions. In hindsight, the end of the eruption was presaged by a slight increase in seismicity in December 2007 that culminated on January 12-13, 2008, with a burst of more than 500 events, most of which occurred in association with several tremor-like signals and a spasmodic burst of long-period earthquakes. At about the same time, a series of regular, localized, small-amplitude tilt events—thousands of which had been recorded during earlier phases of the eruption—came to an end. Thereafter, seismicity declined to 10-20 events per day until January 27-28, when a spasmodic burst of about 50 volcano-tectonic earthquakes occurred over a span of 3 h. This was followed by a brief return of repetitive "drumbeat" earthquakes that characterized much of the eruption. By January 31, however, seismicity had declined to 1-2 earthquakes per day, a rate similar to pre-eruption levels. We attribute the tilt and seismic observations to convulsive stagnation of a semisolid magma plug in the upper part of the conduit. The upward movement of the plug ceased when the excess driving pressure, which had gradually decreased throughout the eruption as a result of reservoir deflation and increasing overburden from the growing dome, was overcome by increasing friction as a result of cooling and crystallization of the plug.

  4. The 2004–2008 dome-building eruption at Mount St. Helens, Washington: Epilogue

    USGS Publications Warehouse

    Dzurisin, Daniel; Moran, Seth C.; Lisowski, Michael; Schilling, Steve P.; Anderson, Kyle R.; Werner, Cynthia A.

    2015-01-01

    The 2004–2008 dome-building eruption at Mount St. Helens ended during winter 2007–2008 at a time when field observations were hampered by persistent bad weather. As a result, recognizing the end of the eruption was challenging—but important for scientists trying to understand how and why long-lived eruptions end and for public officials and land managers responsible for hazards mitigation and access restrictions. In hindsight, the end of the eruption was presaged by a slight increase in seismicity in December 2007 that culminated on January 12–13, 2008, with a burst of more than 500 events, most of which occurred in association with several tremor-like signals and a spasmodic burst of long-period earthquakes. At about the same time, a series of regular, localized, small-amplitude tilt events—thousands of which had been recorded during earlier phases of the eruption—came to an end. Thereafter, seismicity declined to 10–20 events per day until January 27–28, when a spasmodic burst of about 50 volcano-tectonic earthquakes occurred over a span of 3 h. This was followed by a brief return of repetitive “drumbeat” earthquakes that characterized much of the eruption. By January 31, however, seismicity had declined to 1–2 earthquakes per day, a rate similar to pre-eruption levels. We attribute the tilt and seismic observations to convulsive stagnation of a semisolid magma plug in the upper part of the conduit. The upward movement of the plug ceased when the excess driving pressure, which had gradually decreased throughout the eruption as a result of reservoir deflation and increasing overburden from the growing dome, was overcome by increasing friction as a result of cooling and crystallization of the plug.

  5. A prehistoric lahar-dammed lake and eruption of Mount Pinatubo described in a Philippine aborigine legend

    NASA Astrophysics Data System (ADS)

    Rodolfo, Kelvin S.; Umbal, Jesse V.

    2008-10-01

    The prehistoric eruptions of Mount Pinatubo have followed a cycle: centuries of repose terminated by a caldera-forming eruption with large pyroclastic flows; a post-eruption aftermath of rain-triggered lahars in surrounding drainages and dome-building that fills the caldera; and then another long quiescent period. During and after the eruptions lahars descending along volcano channels may block tributaries from watersheds beyond Pinatubo, generating natural lakes. Since the 1991 eruption, the Mapanuepe River valley in the southwestern sector of the volcano has been the site of a large lahar-dammed lake. Geologic evidence indicates that similar lakes have occupied this site at least twice before. An Ayta legend collected decades before Mount Pinatubo was recognized as a volcano describes what is probably the younger of these lakes, and the caldera-forming eruption that destroyed it.

  6. Multiple levels of magma storage during the 1980 summer eruptions of Mount St. Helens, WA

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.; McConnell, S. M.

    2005-11-01

    Transitions in eruptive style—explosive to effusive, sustained to pulsatory—are a common aspect of volcanic activity and present a major challenge to volcano monitoring efforts. A classic example of such transitions is provided by the activity of Mount St. Helens, WA, during 1980, where a climactic Plinian event on May 18 was followed by subplinian and vulcanian eruptions that became increasing pulsatory with time throughout the summer, finally progressing to episodic growth of a lava dome. Here we use variations in the textures, glass compositions and volatile contents of melt inclusions preserved in pyroclasts produced by the summer 1980 eruptions to determine conditions of magma ascent and storage that may have led to observed changes in eruptive activity. Five different pyroclast types identified in pyroclastic flow and fall deposits produced by eruptions in June 12, July 22 and August 7, 1980, provide evidence for multiple levels of magma storage prior to each event. Highly vesicular clasts have H2O-rich (4.5-5.5 wt%) melt inclusions and lack groundmass microlites or hornblende reaction rims, characteristics that require magma storage at P≥160 MPa until shortly prior to eruption. All other clast types have groundmass microlites; PH20 estimated from both H2O-bearing melt inclusions and textural constraints provided by decompression experiments suggest pre-eruptive storage pressures of ˜75, 40, and 10 MPa. The distribution of pyroclast types within and between eruptive deposits can be used to place important constraints on eruption mechanisms. Fall and flow deposits from June 12, 1980, lack highly vesicular, microlite-free pyroclasts. This eruption was also preceded by a shallow intrusion on June 3, as evidenced by a seismic crisis and enhanced SO2 emissions. Our constraints suggest that magma intruded to a depth of ≤4 km beneath the crater floor fed the June eruption. In contrast, eruptions of July and August, although shorter in duration and smaller

  7. Deconvolving the atmospheric impacts of the 1991 eruptions of Mount Pinatubo and Cerro Hudson

    NASA Astrophysics Data System (ADS)

    Case, P. A.; Colarco, P. R.; Toon, B.; Aquila, V.

    2017-12-01

    The eruption of Mount Pinatubo in the Philippines in June 1991 was the largest of the satellite era. The volcanically enhanced stratospheric aerosol layer in the years following the eruption was climatically important: attenuated solar radiation led to cooler surface temperatures, and absorbed longwave radiation led to warmer temperatures in the stratosphere. Further, while most volcanic eruptions observed by satellite have affected only the hemisphere in which they erupted, the Mount Pinatubo eruption had chemical and radiative effects in both hemispheres. Complicating the assessment of Pinatubo's impacts on the climate system was the eruption of Cerro Hudson in southern Chile in August 1991. Cerro Hudson only injected about 15% of sulfur dioxide as Pinatubo, and so has often been neglected in analyses of the post-Pinatubo atmosphere, but it had significant impact on the radiation and chemistry in the southern hemisphere in the months following its eruption. In particular, the rapid transport of the Cerro Hudson plume toward the South Pole led to ozone depletion during the Austral Spring of 1991. In this study we attempt to deconvolve the relative impacts of Pinatubo and Cerro Hudson on the radiation and chemistry in the atmosphere in a series of simulations performed using the Goddard Earth Observing System (GEOS-5) Earth system model with coupled chemistry and aerosol microphysics. We use the sectional Community Aerosol and Radiation Model for Atmospheres (CARMA) to simulate the evolving size distribution and radiative and chemical impacts of the background and volcanically perturbed sulfate aerosol. We perform a series of simulations of the years 1991-1994 investigating the impacts of these volcanic eruptions separately and combined and compare them with satellite and balloon borne in-situ measurements. Our simulations suggest that the Southern Hemisphere response often attributed to Pinatubo was strongly impacted by Cerro Hudson. We also find that the

  8. Forensic recovery of transient eruption parameters for the 2360 BP fall deposit, Mount Meager, British Columbia

    NASA Astrophysics Data System (ADS)

    Campbell, Michelle E.; Porritt, Lucy; Russell, J. K.

    2016-02-01

    The 2360 BP eruption of Mount Meager, Canada featured an explosive subplinian onset resulting in dacitic fallout tephra and associated pumiceous pyroclastic flow deposits, followed by the effusion of dacite lava and the deposition of a thick sequence of block and ash flow deposits. Fall deposits are distributed to the NE of the vent onto a rugged, deeply incised landscape. The central axis of deposition is ~ 063° Az; the lateral margins of the fall deposit are massive to unbedded whereas deposits underlying the plume axis feature complex bedding relationships. We present componentry and granulometry data for eight outcroppings of the fall deposit (four on plume axis and four off plume axis). Vertical cross-sections, based on surface outcrops and drill core logs from local commercial drilling programs, are used to relate the accessory lithics to their source depth in the underlying subvolcanic basement. These combined datasets inform on the dynamics of this explosive phase of the eruption including variations in column height, eruption intensity, atmospheric conditions, and depth to fragmentation front. The lateral variations within the fall strata reflect the effects of the prevailing atmospheric conditions on the form and dispersal pattern of the subplinian plume. Vertical variations in granulometry and componentry of the fall deposits are used to track temporal changes in eruption intensity and column height and the transient influence of the jetstream on the dispersal pattern of the plume. Lastly, vertical variations in lithic componentry, combined with our knowledge of the subsurface geology, are used to quantitatively track the deepening of the fragmentation front. Our computed results show that the fragmentation front migrated from ~ 640 m to ~ 1160 m below the vent over the course of the 2360 BP Mount Meager eruption.

  9. Photogeologic maps of the 2004-2005 Mount St. Helens eruption: Chapter 10 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Herriott, Trystan M.; Sherrod, David R.; Pallister, John S.; Vallance, James W.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The 2004-5 eruption of Mount St. Helens, still ongoing as of this writing (September 2006), has comprised chiefly lava dome extrusion that produced a series of solid, faultgouge-mantled dacite spines. Vertical aerial photographs taken every 2 to 4 weeks, visual observations, and oblique photographs taken from aircraft and nearby observation points provide the basis for two types of photogeologic maps of the dome--photo-based maps and rectified maps. Eight map pairs, covering the period from October 1, 2004, through December 15, 2005, document the development of seven spines: an initial small, fin-shaped vertical spine; a north-south elongate wall of dacite; two large and elongate recumbent spines (“whalebacks”); a tall and elongate inclined spine; a smaller bulbous spine; and an initially endogenous spine extruded between remnants of preceding spines. All spines rose from the same general vent area near the southern margin of the 1980s lava dome. Maps also depict translation and rotation of active and abandoned spines, progressive deformation affecting Crater Glacier, and distribution of ash on the crater floor from phreatic and phreatomagmatic explosions. The maps help track key geologic and geographic features in the rapidly changing crater and help date dome, gouge, and ash samples that are no longer readily correlated to their original context because of deformation in a dynamic environment where spines extrude, deform, slough, and are overrun by newly erupted material.

  10. Impact of Mount St. Helens eruption on hydrology and water quality

    NASA Technical Reports Server (NTRS)

    Bonelli, J. E.; Taylor, H. E.; Klein, J. M.

    1982-01-01

    The 1980 eruptions of Mount St. Helens in southeast Washington resulted in a pronounced effect on the surface and ground water resources of the state. In response to the volcanic activity, the U.S. Geological Survey intensified statewide surface and ground water sampling programs to determine the nature and magnitude of the volcanic-induced variations. Streams to the east of Mount St. Helens received the major ash fallout. Chemical effects were best noted in smaller streams sampled 60 to 70 miles northeast of Mount St. Helens. The chemical variations observed were pronounced but short lived. Sulfate and chloride increases in anionic composition were prevalent immediately following the eruption; however, the original bicarbonate predominance was again attained within several days. Suspended iron and aluminum concentrations were similarly elevated during the period of greatest ash deposition (highest turbidity); however, the dissolved concentrations remained relatively constant. Depressions of pH were minor and short lived. Streams draining to the south, tributaries to the Columbia river, showed little observable changes in water chemistry. Streams draining to the west (Toutle river and its tributaries) were compositionally affected by the various volcanic activities. Chloride and sulfate anion percentage exceeded the bicarbonate percentage up to one month following the eruption period. Streams and lakes sampled in the immediate vicinity of Mount St. Helens, in addition to trace metals, contained organic compounds derived from decomposing wood buried in the debris deposits. This organic material may constitute a significant source of organic compounds to surface and ground water for some time to come.

  11. Impact of Mount St. Helens eruption on hydrology and water quality

    USGS Publications Warehouse

    Bonelli, J.E.; Taylor, Howard E.; Klein, J.M.

    1982-01-01

    The 1980 eruptions of Mount St. Helens in southeast Washington resulted in a pronounced effect on the surface and ground water resources of the state. In response to the volcanic activity, the U.S. Geological Survey intensified statewide surface and ground water sampling programs to determine the nature and magnitude of the volcanic-induced variations. Streams to the east of Mount St. Helens received the major ash fallout. Chemical effects were best noted in smaller streams sampled 60 to 70 miles northeast of Mount St. Helens. The chemical variations observed were pronounced but short lived. Sulfate and chloride increases in anionic composition were prevalent immediately following the eruption however, the original bicarbonate predominance was again attained within several days. Suspended iron and aluminum concentrations were similarly elevated during the period of greatest ash deposition (highest turbidity) however, the dissolved concentrations remained relatively constant. Depressions of pH were minor and short lived. Streams draining to the south, tributaries to the Columbia river, showed little observable changes in water chemistry. Streams draining to the west (Toutle river and its tributaries) were compositionally affected by the various volcanic activities. Chloride and sulfate anion percentage exceeded the bicarbonate percentage up to one month following the eruption period. Streams and lakes sampled in the immediate vicinity of Mount St. Helens, in addition to trace metals, contained organic compounds derived from decomposing wood buried in the debris deposits. This organic material may constitute a significant source of organic compounds to surface and ground water for some time to come.

  12. Eruptive history and geochronology of the Mount Baker volcanic field, Washington

    USGS Publications Warehouse

    Hildreth, W.; Fierstein, J.; Lanphere, M.

    2003-01-01

    Mount Baker, a steaming, ice-mantled, andesitic stratovolcano, is the most conspicuous component of a multivent Quaternary volcanic field active almost continuously since 1.3 Ma. More than 70 packages of lava flows and ~110 dikes have been mapped, ???500 samples chemically analyzed, and ~80 K-Ar and 40Ar/39Ar ages determined. Principal components are (1) the ignimbrite-filled Kulshan caldera (1.15 Ma) and its precaldera and postcaldera rhyodacite lavas and dikes (1.29-0.99 Ma); (2)~60 intracaldera, hydrothermally altered, andesite-dacite dikes and pods-remnants of a substantial early-postcaldera volcanic center (1.1-0.6 Ma); (3) unaltered intracaldera andesite lavas and dikes, including those capping Ptarmigan and Lasiocarpa Ridges and Table Mountain (0.5-0.2 Ma); (4) the long-lived Chowder Ridge focus (1.29-0.1 Ma)-an andesite to rhyodacite eruptive complex now glacially reduced to ~50 dikes and remnants of ~10 lava flows; (5) Black Buttes stratocone, basaltic to dacitic, and several contemporaneous peripheral volcanoes (0.5-0.2 Ma); and (6) Mount Baker stratocone and contemporaneous peripheral volcanoes (0.1 Ma to Holocene). Glacial ice has influenced eruptions and amplified erosion throughout the lifetime of the volcanic field. Although more than half the material erupted has been eroded, liberal and conservative volume estimates for 77 increments of known age yield cumulative curves of volume erupted vs. time that indicate eruption rates in the range 0.17-0.43 km3/k.y. for major episodes and longterm background rates of 0.02-0.07 km3/k.y. Andesite and rhyodacite each make up nearly half of the 161 ?? 56 km3 of products erupted, whereas basalt and dacite represent only a few cubic kilometers, each representing 1%-3% the total. During the past 4 m.y., the principal magmatic focus has migrated stepwise 25 km southwestward, from the edge of the Chilliwack batholith to present-day Mount Baker.

  13. Photogrammetric Analysis of the Current Dome-Building Eruption of Mount St. Helens Volcano

    NASA Astrophysics Data System (ADS)

    Diefenbach, A. K.; Dzurisin, D.; Crider, J. G.; Schilling, S. P.

    2006-12-01

    Beginning in October 2004 and continuing to present day, the eruption of Mount St. Helens has provided a unique opportunity to experiment with new tools and techniques to study the dome-building eruption of a Cascade volcano. At the onset of eruption, a permanent camera station called Sugar Bowl was installed on the northeast rim of the crater about 2 km from the vent. Since that time, four additional cameras have been installed on the rim and crater floor to provide continuous visual observation of dome growth and crater conditions. We have analyzed images from four of the cameras to measure variations in three-dimensional lineal growth rates of lava spines extruding from the growing dome. Using photogrammetric techniques it is possible to obtain quantitative information on the geometry and displacement of a changing topographic model, in this case the evolving dome and glaciers in the crater of Mount St. Helens. The technique is an inexpensive, high-resolution, and efficient method that uses standard commercial software and an off-the-shelf digital camera to determine the x, y, z positions of selected points on the model surface. The model geometry at any given time is defined by the positions of all the points, and displacements are measured by tracking the changing positions of the points through time. Lineal extrusion rates during the first few months of the eruption ranged from 6-11 m/d, and subsequent estimates by other techniques were 4-5 m/d (Dzurisin et. al, 2005). For the past six months the extrusion rate has leveled off at 1 m/d, possibly indicative of steady-state extrusion or an approaching pause in the eruption. Another aspect of the project involves the use of overlapping oblique photos taken from a helicopter in 2004 and 2005 to produce fast and coarse digital elevation models (DEMs), which supplement high resolution DEMs produced by the USGS every 1 - 2 months. Comparing these results with seismicity and ground tilt measured by shallow borehole

  14. The mechanisms of fine particle generation and electrification during Mount St. Helens volcanic eruption

    NASA Technical Reports Server (NTRS)

    Cheng, R. J.

    1982-01-01

    Microscopical investigation of volcanic ash collected from ground stations during Mount St. Helens eruptions reveal a distinctive bimodel size distribution with high concentrations of particle ranges at (1) 200-100 microns and (2) 20-0.1 microns. Close examination of individual particles shows that most larger ones are solidified magma particles of porous pumice with numerous gas bubbles in the interior and the smaller ones are all glassy fragments without any detectable gas bubbles. Elemental analysis demonstrates that the fine fragments all have a composition similar to that of the larger pumice particles. Laboratory experiments suggest that the formation of the fine fragments is by bursting of glassy bubbles from a partially solidified surface of a crystallizing molten magma particle. The production of gas bubbles is due to the release of absorbed gases in molten magma particles when solubility decreases during phase transition. Diffusion cloud chamber experiments strongly indicate that sub-micron volcanic fragments are highly hygroscopic and extremely active as cloud condensation nuclei. Ice crystals also are evidently formed on those fragments in a supercooled (-20 C) cloud chamber. It has been reported that charge generation from ocean volcanic eruptions is due to contact of molten lava with sea water. This seems to be insufficient to explain the observed rapid and intense lightning activities over Mount St. Helens eruptions. Therefore, a hypothesis is presented here that highly electrically charged fine solid fragments are ejected by bursting of gas bubbles from the surface of a crystallizing molten magma particles.

  15. Time correlation by palaeomagnetism of the 1631 eruption of Mount Vesuvius. Volcanological and volcanic hazard implications

    NASA Astrophysics Data System (ADS)

    Carracedo, J. C.; Principe, C.; Rosi, M.; Soler, V.

    1993-11-01

    The 1631 eruption of Mount Vesuvius was the most destructive episode in the recent volcanic history of Vesuvius and the last in which large pyroclastic flows were emitted. The controversy about whether lava flows were also generated in this eruption, as sustained in the mapping by Le Hon (1866) and by the interpretation by some authors (Burri et al., 1975; Rolandi et al., 1991) of eyewitness accounts, is important not only for a better understanding of the eruption but also for the implications in the prediction of volcanic hazards of this volcano, set in an overpopulated area with more than 3 million people potentially at risk. Short-period palaeomagnetic techniques (secular variation curve) have been applied to correlate lava flows interpreted as produced in the event of 1631 with the pyroclastic flow of this same eruption and other lava flows unquestionably emitted prior to this eruptive event. The model that best fits the results obtained suggests that the presumed 1631 lava flows were not the result of a single eruptive event but were, in fact, produced by several different eruptions. These lava flows also have a better palaeomagnetic correlation with the medieval lava flows than with the pyroclastic flow of 1631, whose juvenile pumice clasts have a well-defined single component magnetization that fits in the expected corresponding position of the secular variation curve for that age. The palaeomagnetic characteristics of the 1631 pyroclastic flow are compatible with a "hot" depositional temperature (apparently above the Curie point of magnetite, 585 °C) for the juvenile pumice fragments (magmatic fraction) and a "cold" deposition for the non-magmatic fraction. This suggests the lack of thermal equilibration during transport of the larger clasts, probably due to the short distance travelled by the pyroclastic flows. The main volcanological and volcanic hazard issues of this work are that the 1631 event was entirely explosive and that pyroclastic flow activity

  16. Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon

    USGS Publications Warehouse

    Bacon, Charles R.; Lanphere, Marvin A.

    2006-01-01

    Geologic mapping, K-Ar, and 40Ar/39Ar age determinations, supplemented by paleomagnetic measurements and geochemical data, are used to quantify the Quaternary volcanic history of the Crater Lake region in order to define processes and conditions that led to voluminous explosive eruptions. The Cascade arc volcano known as Mount Mazama collapsed during its climactic eruption of ∼50 km3 of mainly rhyodacitic magma ∼7700 yr ago to form Crater Lake caldera. The Mazama edifice was constructed on a Pleistocene silicic lava field, amidst monogenetic and shield volcanoes ranging from basalt to andesite similar to parental magmas for Mount Mazama. Between 420 ka and 35 ka, Mazama produced medium-K andesite and dacite in 2:1 proportion. The edifice was built in many episodes; some of the more voluminous occurred approximately coeval with volcanic pulses in the surrounding region, and some were possibly related to deglaciation following marine oxygen isotope stages (MIS) 12, 10, 8, 6, 5.2, and 2. Magmas as evolved as dacite erupted many times, commonly associated with or following voluminous andesite effusion. Establishment of the climactic magma chamber was under way when the first preclimactic rhyodacites vented ca. 27 ka. The silicic melt volume then grew incrementally at an average rate of 2.5 km3 k.y.−1 for nearly 20 k.y. The climactic eruption exhausted the rhyodacitic magma and brought up crystal-rich andesitic magma, mafic cumulate mush, and wall-rock granodiorite. Postcaldera volcanism produced 4 km3 of andesite during the first 200–500 yr after collapse, followed at ca. 4800 yr B.P. by 0.07 km3 of rhyodacite. The average eruption rate for all Mazama products was ∼0.4 km3 k.y.−1, but major edifice construction episodes had rates of ∼0.8 km3 k.y.−1. The long-term eruption rate for regional monogenetic and shield volcanoes was d∼0.07 km3 k.y.−1, but only ∼0.02 km3 k.y.−1 when the two major shields are excluded. Plutonic xenoliths and evidence for

  17. Preparatory process preceding the 2014 eruption of Mount Ontake volcano, Japan: insights from precise leveling measurements

    NASA Astrophysics Data System (ADS)

    Murase, Masayuki; Kimata, Fumiaki; Yamanaka, Yoshiko; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Matsushima, Takeshi; Mori, Hitoshi; Ohkura, Takahiro; Yoshikawa, Shin; Miyajima, Rikio; Inoue, Hiroyuki; Mishima, Taketoshi; Sonoda, Tadaomi; Uchida, Kazunari; Yamamoto, Keigo; Nakamichi, Harushisa

    2016-01-01

    Preparatory activity preceding the 2014 eruption of Mount Ontake volcano was estimated from vertical deformation detected using a precise leveling survey. Notable uplift (2006-2009) and subsidence (2009-2014) were detected on the eastern flank of the volcano. We estimated pressure source models based on the vertical deformation and used these to infer preparatory process preceding the 2014 eruption. Our results suggest that the subsidence experienced between 2009 and 2014 (including the period of the 2014 eruption) occurred as a result of a sill-like tensile crack with a depth of 2.5 km. This tensile crack might inflate prior to the eruption and deflate during the 2014 activity. A two-tensile-crack model was used to explain uplift from 2006 to 2009. The geometry of the shallow crack was assumed to be the same as the sill-like tensile crack. The deep crack was estimated to be 2 km in length, 4.5 km in width, and 3 km in depth. Distinct uplifts began on the volcano flanks in 2006 and were followed by seismic activities and a small phreatic eruption in 2007. From the partially surveyed leveling data in August 2013, uplift might continue until August 2013 without seismic activity in the summit area. Based on the uplift from 2006 to 2013, magma ascended rapidly beneath the summit area in December 2006, and deep and shallow tensile cracks were expanded between 2006 and 2013. The presence of expanded cracks between 2007 and 2013 has not been inferred by previous studies. A phreatic eruption occurred on 27 September 2014, and, following this activity, the shallow crack may have deflated.

  18. Proximal ecological effects of the 1980 eruptions of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Swanson, F. J.

    1988-01-01

    The diversity of ecosystems and volcanic processes involved in the 1980 eruptions of Mount St. Helens, southwest Washington, provide an excellent setting for examining effects of volcanic events on ecosystems. These eruptions included a lateral blast, debris avalanche, mudflows, pyroclastic flows, and airfall tephra. Affected ecosystems within 30 km of the vent were lakes, streams, upland and riparian forest, and meadows. Ecological disturbances imposed by the Mount St. Helens events were predominantly physical, rather than climatic or chemical which are the dominant classes of disturbances considered in analysis of global catastrophes. Analysis of ecosystem response to disturbance should be based on consideration of composition and structure of the predisturbance system in terms that represent potential survivability of organisms, mechanisms in the primary disturbance, initial survivors, secondary disturbances arising from the primary disturbance and the biological responses to secondary disturbances, invasion of the site by new propagules, interactions among secondary disturbance processes and surviving and invading organisms. Predicting ecosystem response to disturbance is enchanced by considering the mechanisms of disturbance rather than type of disturbance. In the 1980 Mount St. Helens events, the disturbance types, involved primarily the mechanisms of sedimentation, heating, and shear stress. Each disturbance type involved one or more mechanisms. Ecosystem response varied greatly across the landscape. Analysis of ecosystem response to disturbance, regardless of type, should include detailed consideration of the properties of individual species, primary and secondary disturbance mechanisms, and their distributions across landscapes.

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

    USGS Publications Warehouse

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

    1985-01-01

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

  20. Field-trip guide to Mount Hood, Oregon, highlighting eruptive history and hazards

    USGS Publications Warehouse

    Scott, William E.; Gardner, Cynthia A.

    2017-06-22

    This guidebook describes stops of interest for a geological field trip around Mount Hood volcano. It was developed for the 2017 International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) Scientific Assembly in Portland, Oregon. The intent of this guidebook and accompanying contributions is to provide an overview of Mount Hood, including its chief geologic processes, magmatic system, eruptive history, local tectonics, and hazards, by visiting a variety of readily accessible localities. We also describe coeval, largely monogenetic, volcanoes in the region. Accompanying the field-trip guidebook are separately authored contributions that discuss in detail the Mount Hood magmatic system and its products and behavior (Kent and Koleszar, this volume); Mount Hood earthquakes and their relation to regional tectonics and the volcanic system (Thelen and Moran, this volume); and young surface faults cutting the broader Mount Hood area whose extent has come to light after acquisition of regional light detection and ranging coverage (Madin and others, this volume).The trip makes an approximately 175-mile (280-kilometer) clockwise loop around Mount Hood, starting and ending in Portland. The route heads east on Interstate 84 through the Columbia River Gorge National Scenic Area. The guidebook points out only a few conspicuous features of note in the gorge, but many other guides to the gorge are available. The route continues south on the Mount Hood National Scenic Byway on Oregon Route 35 following Hood River, and returns to Portland on U.S. Highway 26 following Sandy River. The route traverses rocks as old as the early Miocene Eagle Creek Formation and overlying Columbia River Basalt Group of middle Miocene age, but chiefly lava flows and clastic products of arc volcanism of late Miocene to Holocene age.

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

    NASA Astrophysics Data System (ADS)

    Bacon, Charles R.

    1983-10-01

    New investigations of the geology of Crater Lake National Park necessitate a reinterpretation of the eruptive history of Mount Mazama and of the formation of Crater Lake caldera. Mount Mazama consisted of a glaciated complex of overlapping shields and stratovolcanoes, each of which was probably active for a comparatively short interval. All the Mazama magmas apparently evolved within thermally and compositionally zoned crustal magma reservoirs, which reached their maximum volume and degree of differentiation in the climactic magma chamber ˜ 7000 yr B.P. The history displayed in the caldera walls begins with construction of the andesitic Phantom Cone ˜ 400,000 yr B.P. Subsequently, at least 6 major centers erupted combinations of mafic andesite, andesite, or dacite before initiation of the Wisconsin Glaciation ˜ 75,000 yr B.P. Eruption of andesitic and dacitic lavas from 5 or more discrete centers, as well as an episode of dacitic pyroclastic activity, occurred until ˜ 50,000 yr B.P.; by that time, intermediate lava had been erupted at several short-lived vents. Concurrently, and probably during much of the Pleistocene, basaltic to mafic andesitic monogenetic vents built cinder cones and erupted local lava flows low on the flanks of Mount Mazama. Basaltic magma from one of these vents, Forgotten Crater, intercepted the margin of the zoned intermediate to silicic magmatic system and caused eruption of commingled andesitic and dacitic lava along a radial trend sometime between ˜ 22,000 and ˜ 30,000 yr B.P. Dacitic deposits between 22,000 and 50,000 yr old appear to record emplacement of domes high on the south slope. A line of silicic domes that may be between 22,000 and 30,000 yr old, northeast of and radial to the caldera, and a single dome on the north wall were probably fed by the same developing magma chamber as the dacitic lavas of the Forgotten Crater complex. The dacitic Palisade flow on the northeast wall is ˜ 25,000 yr old. These relatively silicic

  2. What's new? Identifying juvenile magma in early-erupted ash samples from Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Cashman, K.; Thornber, C.; Pallister, J.; Hoblitt, R.; Wright, H.; Lowers, H.; Brownfield, I.; Meeker, G.

    2004-12-01

    Volcanic eruptions are often preceded by early emissions of steam and ash. Identification of juvenile magma in these early ash deposits is important for determining the possible course of the ensuing eruption. A common assumption is that juvenile material will appear in the form of vesicular glass or glass shards. However, when the magma is H2O-rich and is ascending slowly, juvenile magma may experience extensive gas loss and degassing-induced crystallization en route to the surface. The result is juvenile material that is dense and finely crystalline. We illustrate this effect using examples of ash emitted from Mount St. Helens from March-May 1980 and September-October 2004. Steam and ash emissions accompanied the emplacement of a cryptodome into the edifice of Mount St. Helens in 1980, preceding edifice failure and the climactic eruption of May 18. Cryptodome samples are choked with very small crystals of plagioclase and mafic phases; matrix glass is either pristine or devitrified to fine intergrowths of quartz and plagioclase. We have identified ash particles with similar textures within deposits produced by early steam-and-ash emissions, indicating that those explosions were phreatomagmatic, rather than strictly phreatic, as is commonly assumed. Similarly, early steam-and-ash emissions from the 2004 activity contain small amounts of dense finely crystalline juvenile ash fragments in addition to abundant loose crystals and fragments of older edifice material. These samples also contain pumice fragments that are not juvenile, but instead appear to be part of the crater fill developed in 1980. Preliminary assessment of ash samples collected during the first few weeks of October suggest that the proportion of juvenile material increased with time. Initial interpretation of these textures was that the magma was rising slowly from moderate (< 4km) depths. Subsequent imaging of samples collected directly from the new lava dome confirm the juvenile origin of the dense

  3. Decadal-scale post-eruptive river evolution: Lessons learned from Mount Pinatubo

    NASA Astrophysics Data System (ADS)

    Gran, K. B.

    2016-12-01

    One of the most devastating aspects of the 1991 Pinatubo eruption was the hydrologic aftermath, with repeated lahars flowing down major river valleys for years after the eruption. On the east flank of Pinatubo, sediment yields > 3 million m3/km2/yr were mobilized, with yields decaying exponentially for the first decade. Due to a dearth of post-eruption river recovery studies, predicting longer-term sediment yields remains a challenge. This study reports on river evolution in the second decade following the Pinatubo eruption, at a time when most lahars had ceased and normal fluvial processes dominated sediment mobilization and transport. Field measurements of bed roughness, cross-sectional and long profile geometry, and bedload and suspended load transport were made on a series of rivers on the east flank of Pinatubo, with most effort on the Pasig-Potrero River. Measurements from 1996 - 2011 were used to develop a conceptual model for the pace and pattern of post-eruption channel recovery. Since the late 1990s, channels have coarsened as pumice and sand preferentially transport downstream. Coarsening occurred first in the upper basin during the dry season, extending downstream and lasting longer into the rainy season over time. By the end of the second decade, the upper basin of the Pasig-Potrero River contained gravel-bedded, single-thread channels even during the rainy season. Although the alluvial fan remained sandy and braided during the rainy season, it now armors during the dry season, with armoring and incision occurring as a migrating downstream wave. Comparisons of long-term fluvial recovery from Pinatubo and the North Fork Toutle River at Mount St. Helens show that after an initial exponential decay period, sediment loads tend to remain much higher than pre-eruption loads, driven by continued channel instability. At Pinatubo, this channel instability continues in the braidplains on alluvial fans. Fundamentally, the lesson learned at Pinatubo and Mount St

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

    NASA Astrophysics Data System (ADS)

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

    1984-10-01

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

  5. 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

  6. Mount St. Helens erupts again: activity from September 2004 through March 2005

    USGS Publications Warehouse

    Major, Jon J.; Scott, William E.; Driedger, Carolyn; Dzurisin, Dan

    2005-01-01

    Eruptive activity at Mount St. Helens captured the world’s attention in 1980 when the largest historical landslide on Earth and a powerful explosion reshaped the volcano, created its distinctive crater, and dramatically modified the surrounding landscape. Over the next 6 years, episodic extrusions of lava built a large dome in the crater. From 1987 to 2004, Mount St. Helens returned to a period of relative quiet, interrupted by occasional, short-lived seismic swarms that lasted minutes to days, by months-to-yearslong increases in background seismicity that probably reflected replenishment of magma deep underground, and by minor steam explosions as late as 1991. During this period a new glacier grew in the crater and wrapped around and partly buried the lava dome. Although the volcano was relatively quiet, scientists with the U.S. Geological Survey and University of Washington’s Pacific Northwest Seismograph Network continued to closely monitor it for signs of renewed activity.

  7. Timing of degassing and plagioclase growth in lavas erupted from Mount St. Helens, 2004-2005, from 210Po-210Pb-226Ra disequilibria: Chapter 37 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Reagan, Mark K.; Cooper, Kari M.; Pallister, John S.; Thornber, Carl R.; Wortel, Matthew; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Disequilibrium between 210Po, 210Pb, and 226Ra was measured on rocks and plagioclase mineral separates erupted during the first year of the ongoing eruption of Mount St. Helens. The purpose of this study was to monitor the volatile fluxing and crystal growth that occurred in the weeks, years, and decades leading up to eruption. Whole-rock samples were leached in dilute HCl to remove 210Po precipitated in open spaces. Before leaching, samples had variable initial (210Po) values, whereas after leaching, the groundmasses of nearly all juvenile samples were found to have had (210Po) ≈ 0 when they erupted. Thus, most samples degassed 210Po both before and after the magmas switched from open- to closed-system degassing. All juvenile samples have (210Pb)/(226Ra) ratios within 2 δ of equilibrium, suggesting that the magmas involved in the ongoing eruption did not have strong, persistent fluxes of 222Rn in or out of magmas during the decades and years leading to eruption. These equilibrium values also require a period of at least a century after magma generation and the last significant differentiation of the Mount St. Helens dacites. Despite this, the elevated (210Pb)/(226Ra) value measured in a plagioclase mineral separate from lava erupted in 2004 suggests that a significant proportion of this plagioclase grew within a few decades of eruption. The combined dataset suggests that for most 2004-5 lavas, the last stage of open-system degassing of the dacite magmas at Mount St. Helens is confined to the period between 1-2 years and 1-2 weeks before eruption, whereas plagioclase large enough to be included in the mineral separate grew around the time of the 1980s eruption or earlier.

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

    USGS Publications Warehouse

    Bacon, C.R.

    1983-01-01

    New investigations of the geology of Crater Lake National Park necessitate a reinterpretation of the eruptive history of Mount Mazama and of the formation of Crater Lake caldera. Mount Mazama consisted of a glaciated complex of overlapping shields and stratovolcanoes, each of which was probably active for a comparatively short interval. All the Mazama magmas apparently evolved within thermally and compositionally zoned crustal magma reservoirs, which reached their maximum volume and degree of differentiation in the climactic magma chamber ??? 7000 yr B.P. The history displayed in the caldera walls begins with construction of the andesitic Phantom Cone ??? 400,000 yr B.P. Subsequently, at least 6 major centers erupted combinations of mafic andesite, andesite, or dacite before initiation of the Wisconsin Glaciation ??? 75,000 yr B.P. Eruption of andesitic and dacitic lavas from 5 or more discrete centers, as well as an episode of dacitic pyroclastic activity, occurred until ??? 50,000 yr B.P.; by that time, intermediate lava had been erupted at several short-lived vents. Concurrently, and probably during much of the Pleistocene, basaltic to mafic andesitic monogenetic vents built cinder cones and erupted local lava flows low on the flanks of Mount Mazama. Basaltic magma from one of these vents, Forgotten Crater, intercepted the margin of the zoned intermediate to silicic magmatic system and caused eruption of commingled andesitic and dacitic lava along a radial trend sometime between ??? 22,000 and ??? 30,000 yr B.P. Dacitic deposits between 22,000 and 50,000 yr old appear to record emplacement of domes high on the south slope. A line of silicic domes that may be between 22,000 and 30,000 yr old, northeast of and radial to the caldera, and a single dome on the north wall were probably fed by the same developing magma chamber as the dacitic lavas of the Forgotten Crater complex. The dacitic Palisade flow on the northeast wall is ??? 25,000 yr old. These relatively

  9. Time variations of aerosols in the stratosphere following Mount St. Helens eruptions

    NASA Astrophysics Data System (ADS)

    Farlow, N. H.; Snetsinger, K. G.; Oberbeck, V. R.; Ferry, G. V.; Polkowski, G.; Hayes, D. M.

    1982-10-01

    Samples of stratospheric aerosols collected with U-2 aircraft for several months following the first three major eruptions of Mount St. Helens were analyzed for ash and liquid acid content. Ash grain sizes and compositions vary depending on collection altitude, location within the drifting cloud, and days following their injection. s computers Size distributions of ash particles vary with altitude. Generally small particles are depleted more rapidly at low altitudes (12 km) than at higher altitudes (17-18 km). Although samples collected 1 day after the first eruption of May 18, 1980, were dry, flow marks on the aircraft indicated parts of the cloud contained heavy acid concentrations. Indeed, all other samples obtained within 1 to 4 days after later eruptions (May 25 and June 12, 1980) were covered with copious amounts of liquid acid. Proportions of liquid to ash varied considerably depending on sampling location and cloud age. Because the acid-coated ash globules were large, they rapidly fell from the stratosphere until, by late June 1980, only a residue of acid droplets remained. Size distributions and concentrations of these droplets varied considerably.

  10. Ash loading and insolation at Hanford, Washington during and after the eruption of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Laulainen, N. S.

    1982-01-01

    The effects of volcanic ash suspended in the atmosphere on the incident solar radiation was monitored at the Hanford Meteorological Station (HMS) subsequent to the major eruption of Mount St. Helens on May 18, 1980. Passage of the ash plume over Hanford resulted in a very dramatic decrease of solar radiation intensity to zero. A reduction in visibility to less than 1 km was observed, as great quantities of ash fell out of the plume onto the ground. Ash loading in the atmosphere remained very high for several days following the eruption, primarily as a result of resuspension from the surface. Visibilities remained low (2 to 8 km) during this period. Estimates of atmospheric turbidity were made from the ratio of diffuse-to-direct solar radiation; these turbidities were used to estimate extinction along a horizontal path, a quantity which can be related to visibility. Comparisons of observed and estimated visibilities were very good, in spite of the rather coarse approximations used in the estimates. Atmospheric clarity and visibility improved to near pre-eruption conditions following a period of rain showers. The diffuse-to-direct ratio of solar radiation provided a useful index for estimating volcanic ash loading of the atmosphere.

  11. Time variations of aerosols in the stratosphere following Mount St. Helens eruptions

    NASA Technical Reports Server (NTRS)

    Farlow, N. H.; Snetsinger, K. G.; Oberbeck, V. R.; Ferry, G. V.; Polkowski, G.; Hayes, D. M.

    1982-01-01

    Samples of stratospheric aerosols collected with U-2 aircraft for several months following the first three major eruptions of Mount St. Helens were analyzed for ash and liquid acid content. Ash grain sizes and compositions vary depending on collection altitude, location within the drifting cloud, and days following their injection. s computers Size distributions of ash particles vary with altitude. Generally small particles are depleted more rapidly at low altitudes (12 km) than at higher altitudes (17-18 km). Although samples collected 1 day after the first eruption of May 18, 1980, were dry, flow marks on the aircraft indicated parts of the cloud contained heavy acid concentrations. Indeed, all other samples obtained within 1 to 4 days after later eruptions (May 25 and June 12, 1980) were covered with copious amounts of liquid acid. Proportions of liquid to ash varied considerably depending on sampling location and cloud age. Because the acid-coated ash globules were large, they rapidly fell from the stratosphere until, by late June 1980, only a residue of acid droplets remained. Size distributions and concentrations of these droplets varied considerably.

  12. Mount St. Helens eruptions: the acute respiratory effects of volcanic ash in a North American community.

    PubMed

    Baxter, P J; Ing, R; Falk, H; Plikaytis, B

    1983-01-01

    After the May 18, 1980 volcanic eruption of Mount St. Helens, increases were observed in the number of patients who, because of asthma or bronchitis, sought medical care at emergency rooms of major hospitals in areas of ashfall. An interview study of 39 asthma and 44 bronchitis patients who became sick during the 4 wk following the eruption and who attended the emergency rooms of two major hospitals in Yakima, Washington, and of healthy matched controls indicated that a history of asthma, and possibly of bronchitis, were risk factors for contracting respiratory problems. The interview study also indicated that the main exacerbating factor was the elevated level of airborne total suspended particulates (in excess of 30,000 micrograms/m3) after the eruption. An interview study of 97 patients who had chronic lung disease and who lived in the same area as the above-mentioned patients, but who did not go to a hospital, showed that the ashfall exacerbated the condition in about one-third of these. Emergency planners and their geologist advisers should be aware that special preventive measures are justified for people with a history of asthma or chronic lung disease who live in communities at risk to volcanic ashfalls.

  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. Dispersion of the Volcanic Sulfate Cloud from the Mount Pinatubo Eruption

    NASA Technical Reports Server (NTRS)

    Aquila, Valentina; Oman, Luke D.; Stolarski, Richard S.; Colarco, Peter R.; Newman, Paul A.

    2012-01-01

    We simulate the transport of the volcanic cloud from the 1991 eruption of Mount Pinatubo with the GEOS-5 general circulation model. Our simulations are in good agreement with observational data. We tested the importance of initial condition corresponding to the specific meteorological situation at the time of the eruption by employing reanalysis from MERRA. We found no significant difference in the transport of the cloud. We show how the inclusion of the interaction between volcanic sulfate aerosol and radiation is essential for a reliable simulation of the transport of the volcanic cloud. The absorption of long wave radiation by the volcanic sulfate induces a rising of the volcanic cloud up to the middle stratosphere, combined with divergent motion from the latitude of the eruption to the tropics. Our simulations indicate that the cloud diffuses to the northern hemisphere through a lower stratospheric pathway, and to mid- and high latitudes of the southern hemisphere through a middle stratospheric pathway, centered at about 30 hPa. The direction of the middle stratospheric pathway depends on the season. We did not detect any significant change of the mixing between tropics and mid- and high latitudes in the southern hemisphere.

  15. 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.

  16. Constraints and conundrums resulting from ground-deformation measurements made during the 2004-2005 dome-building eruption of Mount St. Helens, Washington: Chapter 14 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Dzurisin, Daniel; Lisowski, Michael; Poland, Michael P.; Sherrod, David R.; LaHusen, Richard G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Lack of precursory inflation suggests that the volcano was poised to erupt magma already stored in a crustal reservoir when JRO1 was installed in 1997. Trilateration and campaign GPS data indicate surface dilatation, presumably caused by reservoir expansion between 1982 and 1991, but no measurable deformation between 1991 and 2003. We conclude that all three of the traditionally reliable eruption precursors (seismicity, ground deformation, and volcanic gas emission) failed to provide warning that an eruption was imminent until a few days before a visible welt appeared at the surface--a situation reminiscent of the 1980 north-flank bulge at Mount St. Helens.

  17. Global temperature response to the major volcanic eruptions in multiple reanalysis datasets

    NASA Astrophysics Data System (ADS)

    Fujiwara, M.; Hibino, T.; Mehta, S. K.; Gray, L.; Mitchell, D.; Anstey, J.

    2015-05-01

    Global temperature response to the eruptions of Mount Agung in 1963, El Chichón in 1982 and Mount Pinatubo in 1991 is investigated using nine reanalysis datasets (JRA-55, MERRA, ERA-Interim, NCEP-CFSR, JRA-25, ERA-40, NCEP-1, NCEP-2, and 20CR). Multiple linear regression is applied to the zonal and monthly mean time series of temperature for two periods, 1979-2009 (for eight reanalysis datasets) and 1958-2001 (for four reanalysis datasets), by considering explanatory factors of seasonal harmonics, linear trends, Quasi-Biennial Oscillation, solar cycle, and El Niño Southern Oscillation. The residuals are used to define the volcanic signals for the three eruptions separately. In response to the Mount Pinatubo eruption, most reanalysis datasets show strong warming signals (up to 2-3 K for one-year average) in the tropical lower stratosphere and weak cooling signals (down to -1 K) in the subtropical upper troposphere. For the El Chichón eruption, warming signals in the tropical lower stratosphere are somewhat smaller than those for the Mount Pinatubo eruption. The response to the Mount Agung eruption is asymmetric about the equator with strong warming in the Southern Hemisphere midlatitude upper troposphere to lower stratosphere. The response to three other smaller-scale eruptions in the 1960s and 1970s is also investigated. Comparison of the results from several different reanalysis datasets confirms the atmospheric temperature response to these major eruptions qualitatively, but also shows quantitative differences even among the most recent reanalysis datasets.

  18. A comparison of thermal observations of mount st. Helens before and during the first week of the initial 1980 eruption.

    PubMed

    Lawrence, W S; Qamar, A; Moore, J; Kendrick, G

    1980-09-26

    Before and during the first week of the March-April 1980 eruptions of Mount St. Helens, Washington, infrared thermal surveys were conducted to monitor the thermal activity of the volcano. The purpose was to determine if an increase in thermal activity had taken place since an earlier airborne survey in 1966. Nine months before the eruption there was no evidence of an increase in thermal activity. The survey during the first week of the 1980 eruptions indicated that little or no change in thermal activity had taken place up to 4 April. Temperatures of ejected ash and steam were low and never exceeded 15 degrees C directly above the vent.

  19. Techniques for Measuring Lava Dome Growth During the 2004 2006 Eruption of Mount St. Helens, Washington

    NASA Astrophysics Data System (ADS)

    Schilling, S. P.; Dzurisin, D.; Thompson, R. A.; Messerich, J.; Herd, R.; Diefenbach, A.

    2006-12-01

    Since the current eruption at Mount St. Helens began in October 2004, we have used vertical and oblique photogrammetry and pre-eruption lidar data to calculate volumes and extrusion rates of the growing lava dome and to document topographic changes in the surrounding crater. At approximately three-week intervals, vertical aerial photographs are acquired along a single flight line centered over the crater at a nominal 1:12000 scale. The photographs are scanned at 12-micron resolution, entered into a soft-copy stereoplotter system for orientation and aerotriangulation, and used to create 2-m-resolution digital elevation models (DEMs) of the dome and adjacent glacier. Pre-eruption GPS sites outside the area of active deformation and photogrammetric data passed to subsequent stereo model sets are used as ground control. Resulting positional accuracy is on the order of centimeters to decimeters. To quantify volumetric changes associated with dome growth, collapse, and glacier deformation, each DEM is compared to pre-eruption reference DEMs for 1986 (derived from topographic contours) and 2003 (from lidar), as well as to each preceding DEM. Volume and extrusion rate as functions of time are critical parameters used to constrain models of the magmatic system, relate measured emission rates of magmatic gases to the magma supply rate, interpret earthquake processes and changing patterns of seismicity, and constrain calculations of the loading effect of the growing dome on measurements of ground deformation. Five digital cameras installed on the crater rim and floor monitor the eruption, document short-lived events such as rockfalls and small explosions, and produce time-lapse animations of the changing topography. Recently, we have begun to measure deformation using images acquired every 10 minutes by these cameras to supplement the less-frequent DEMs. We employ software that uses epipolar equations to calculate coordinates of mobile points that are visible from two or more

  20. Chronology and pyroclastic stratigraphy of the May 18, 1980, eruption of Mount St. Helens, Washington

    NASA Technical Reports Server (NTRS)

    Criswell, C. William

    1987-01-01

    The eruption of Mount St. Helens on May 18, 1980 can be subdivided into six phases: the paroxysmal phase I, the early Plinian phase II, the early ash flow phase III, the climactic phase IV, the late ash flow phase V, and phase VI, the activity of which consisted of a low-energy ash plume. These phases are correlated with stratigraphic subunits of ash-fall tephra and pyroclastic flow deposits. Sustained vertical discharge of phase II produced evolved dacite with high S/Cl ratios. Ash flow activity of phase III is attributed to decreases in gas content, indicated by reduced S/Cl ratios and increased clast density of the less evolved gray pumice. Climactic events are attributed to vent clearing and exhaustion of the evolved dacite.

  1. Forward scattering and backscattering of solar radiation by the stratospheric limb after Mount St. Helens eruption

    NASA Technical Reports Server (NTRS)

    Ackerman, M.; Lippens, C.

    1982-01-01

    Stratospheric limb radiance profiles versus altitude of closest approach of the line of sight to the Earth's surface have been measured before and after the Mount St. Helens eruptions by means of photographs taken from a Sun-oriented balloon gondola floating above 35 km altitude over France. Preliminary data were reported for flights in October 1979 and in May and June 1980. The radiance integrated along the line of sight as in-situ radiance (R) can be derived taking into account absorption by ozone and air. The onion peeling inversion method was used to derive the vertical radiance (R) profiles respectively. The values of R were determined in the solar azimuth. The solar elevation angles are chosen larger for the backscattering observation than for the forward scattering observation to deal with as similar illumination conditions as possible despite the Earth's sphericity.

  2. Gas emissions and the eruptions of mount st. Helens through 1982.

    PubMed

    Casadevall, T; Rose, W; Gerlach, T; Greenland, L P; Ewert, J; Wunderman, R; Symonds, R

    1983-09-30

    The monitoring of gas emissions from Mount St. Helens includes daily airborne measurements of sulfur dioxide in the volcanic plume and monthly sampling of gases from crater fumaroles. The composition of the fumarolic gases has changed slightly since 1980: the water content increased from 90 to 98 percent, and the carbon dioxide concentrations decreased from about 10 to 1 percent. The emission rates of sulfur dioxide and carbon dioxide were at their peak during July and August 1980, decreased rapidly in late 1980, and have remained low and decreased slightly through 1981 and 1982. These patterns suggest steady outgassing of a single batch of magma (with a volume of not less than 0.3 cubic kilometer) to which no significant new magma has been added since mid-1980. The gas data were useful in predicting eruptions in August 1980 and June 1981.

  3. Gaseous constituents in the plume from eruptions of mount st. Helens.

    PubMed

    Inn, E C; Vedder, J F; Condon, E P; O'hara, D

    1981-02-20

    Measurements in the stratosphere of gaseous constituents in the plume of Mount St. Helens were obtained during five flights of the NASA U-2 aircraft between 19 May and 17 June 1980. Mixing ratios from gas chromatographic measurements on samples acquired about 24 hours after the initial eruption show considerable enhancement over nonvolcanic concentrations for sulfur dioxide (more than 1000 times), methyl chloride (about 10 times), and carbon disulfide (more than 3 times). The mixing ratio of carbonyl sulfide was comparable to nonvolcanic mixing ratios although 3 days later it was enhanced two to three times. Ion chromatography measurements on water-soluble constituents are also reported. Very large concentrations of chloride, nitrate, and sulfate ions were measured, implying large mixing ratios for the water-soluble gaseous constituents from which the anions are derived. Measurements of radon-222 present in the plume are also reported.

  4. Gaseous constituents in the plume from eruptions of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Inn, E. C. Y.; Vedder, J. F.; Condon, E. P.; Ohara, D.

    1981-01-01

    Measurements in the stratosphere of gaseous constituents in the plume of Mount St. Helens were obtained during five flights of the NASA U-2 aircraft between 19 May and 17 June 1980. Mixing ratios from gas chromatographic measurements on samples acquired about 24 hours after the initial eruption show considerable enhancement over nonvolcanic concentrations for sulfur dioxide (more than 1000 times), methyl chloride (about 10 times), and carbon disulfide (more than 3 times). The mixing ratio of carbonyl sulfide was comparable to nonvolcanic mixing ratios although 3 days later it was enhanced two to three times. Ion chromatography measurements on water-soluble constituents are also reported. Very large concentrations of chloride, nitrate, and sulfate ions were measured, implying large mixing ratios for the water-soluble gaseous constituents from which the anions are derived. Measurements of radon-222 present in the plume are also reported.

  5. Impact of Mount St. Helens Eruption on Bacteriology of Lakes in the Blast Zone

    PubMed Central

    Staley, J. T.; Lehmicke, L. G.; Palmer, F. E.; Peet, R. W.; Wissmar, R. C.

    1982-01-01

    Lakes lying within the blast zone of Mount St. Helens showed dramatic increases in heterotrophic bacterial numbers after the eruption of 18 May 1980. The total microscopic counts of bacteria in some of the most severely affected lakes were more than 107 cells per ml, an order of magnitude above the counts in outlying control lakes. Likewise, the numbers of viable bacteria reached levels of more than 106 cells per ml, compated with fewer than 104 cells per ml in control lakes. The CPS medium used for enumeration provided growth of up to 81.5% of the bacteria during sampling of one of the blast zone lakes. The high numbers of bacteria and the efficacy of the viable enumeration procedure are evidence that the lakes have been transformed rapidly from oligotrophy to eutrophy due to the eruption and its aftermath. Organic material leached from the devastated forest vegetation is thought to be responsible for the enrichment of heterotrophs. Total coliform bacteria were found in all of the blast zone lakes, and some lakes contained fecal coliform bacteria. Klebsiella pneumoniae was the predominant total coliform and was also identified as one of the fecal coliform bacteria, although Escherichia coli was the predominant species in that category. Our data indicate that bacterial populations peaked in the outer blast zone lakes in the summer of 1980 and in most of the inner lakes during the summer of 1981. PMID:16345973

  6. The 1980 eruptions of Mount St. Helens - Physical and chemical processes in the stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Toon, O. B.; Whitten, R. C.; Hamill, P.; Keesee, R. G.

    1983-01-01

    The large and diverse set of observational data collected in the high-altitude plumes of the May 18, May 25, and June 13, 1980 eruptions is organized and analyzed with a view to discerning the processes at work. The data serve to guide and constrain detailed model simulations of the volcanic clouds. For this purpose, use is made of a comprehensive one-dimensional model of stratospheric sulfate aerosols, sulfur precursor gases, and volcanic ash and dust. The model takes into account gas-phase and condensed-phase (heterogeneous) chemistry in the clouds, aerosol nucleation and growth, and cloud expansion. Computational results are presented for the time histories of the gaseous species concentrations, aerosol size distributions, and ash burdens of the eruption clouds. Also investigated are the long-term buildup of stratospheric aerosols in the Northern Hemisphere and the persistent effects of injected chlorine and water vapor on stratospheric ozone. It is concluded that SO2, water vapor, and ash were probably the most important substances injected into the stratosphere by the Mount St. Helens volcano, both with respect to their widespread effects on composition and their effect on climate.

  7. Impact of mount st. Helens eruption on bacteriology of lakes in the blast zone.

    PubMed

    Staley, J T; Lehmicke, L G; Palmer, F E; Peet, R W; Wissmar, R C

    1982-03-01

    Lakes lying within the blast zone of Mount St. Helens showed dramatic increases in heterotrophic bacterial numbers after the eruption of 18 May 1980. The total microscopic counts of bacteria in some of the most severely affected lakes were more than 10 cells per ml, an order of magnitude above the counts in outlying control lakes. Likewise, the numbers of viable bacteria reached levels of more than 10 cells per ml, compated with fewer than 10 cells per ml in control lakes. The CPS medium used for enumeration provided growth of up to 81.5% of the bacteria during sampling of one of the blast zone lakes. The high numbers of bacteria and the efficacy of the viable enumeration procedure are evidence that the lakes have been transformed rapidly from oligotrophy to eutrophy due to the eruption and its aftermath. Organic material leached from the devastated forest vegetation is thought to be responsible for the enrichment of heterotrophs. Total coliform bacteria were found in all of the blast zone lakes, and some lakes contained fecal coliform bacteria. Klebsiella pneumoniae was the predominant total coliform and was also identified as one of the fecal coliform bacteria, although Escherichia coli was the predominant species in that category. Our data indicate that bacterial populations peaked in the outer blast zone lakes in the summer of 1980 and in most of the inner lakes during the summer of 1981.

  8. GOES weather satellite observations and measurements of the May 18, 1980, Mount St. Helens eruption

    NASA Technical Reports Server (NTRS)

    Holasek, R. E.; Self, S.

    1995-01-01

    We demonstrate the use of Geostationary Operational Environmental Satellite (GOES) images of the May 18, 1980, Mount St. Helens volcanic plume in providing details of the dynamics and changing character of this major explosive eruption. Visible and thermal infrared (IR) data from a sequence of images at 30-min intervals from 0850 to 1720 Local Time (LT) give information on dispersal and plume top temperature. Initial visible and IR images at 0850 show the top of a spreading co-ignimbrite-like umbrella plume and an overshooting column emerging from it, both rising off the ground-hugging pyroclastic gravity flow generated by the opening directed blast. The overshooting column had a minimum temperature significantly colder than local ambient atmosphere, indicating substantial undercooling, and a maximum altitude of 31 +/- 2 km at 0920. This large plume system then formed a high-velocity, radially spreading, gravitationally driven current before becoming advected in the wind field at an average downwind velocity of 29 m/s. Reflectance values from visible GOES data change from lower to higher during periods of transition from darker toned Plinian to lighter toned co-ignimbrite plumes indicating that in this case satellite data resolved changes in eruptive style from plumes with a coarser to a finer dominant particle size.

  9. Cyclic ground tilt associated with the 2004-2008 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Lisowski, M.; Segall, P.

    2010-11-01

    The long-term behavior of the 2004-2008 effusive eruption of Mount St. Helens was characterized by a gradual decline in the rates of seismicity, dome growth, and broad-scale ground deformation, but shallow near-periodic "drumbeat" earthquakes over timescales of minutes indicated episodic short-term behavior. In part to better characterize this behavior and any associated ground deformation, a network of tiltmeters was installed and recorded thousands of cyclic tilt events within the crater. The duration of these events, from minutes to hours, was too long for them to be directly caused by the drumbeat seismicity. Tilt events were characterized by a recoverable, asymmetric pattern of rapid tilt away from the vent followed by a more gradual reversal, were highly correlated between different tiltmeters in the crater, sometimes occurred in association with volcanic seismicity, and ceased at the end of the eruption. Tilt vectors converged on a point just south of the center of the preexisting 1980s lava dome, and the absence of detectable tilt outside the crater suggests a shallow source (<1 km). We examine several models, including cycles of conduit pressurization and plug slip or gas loss and stick-slip behavior on the interface between the ascending plug and the 1980s lava dome. The small number of stations within the crater prevents a unique determination of source type or geometry, but results are consistent with a mechanism involving extrusion of the semisolid dacite plug and/or cycles of conduit pressurization.

  10. Precise relocation of earthquakes following the 15 June 1991 eruption of Mount Pinatubo (Philippines)

    USGS Publications Warehouse

    Battaglia, J.; Thurber, C.H.; Got, J.-L.; Rowe, C.A.; White, R.A.

    2004-01-01

    The 15 June 1991 climactic eruption of Mount Pinatubo (Philippines) was followed by intense seismicity that remained at a high level for several months. We located 10,839 events recorded between 1 July and mid-December 1991. In contrast to the preeruptive seismicity which was focused in two groups below the summit area, posteruptive events were widely distributed below and around the volcano. The classification of the events indicates the presence of several large multiplets, and the application of relative relocation techniques to the similar events by calculating high-precision delays between traces outlines a number of clear seismogenic structures. We used different methods to confirm the validity of our results; these tests indicate that reliable features can be detected with a small monitoring network. While the main cluster of activity can be attributed to an intrusive process starting from below the 15 June crater, the volcanic origin of the seismic activity in the other areas is more difficult to establish. Away from the summit, relocations define streaks or planes which are oriented predominantly southwest-northeast, with in several cases the presence of northwest-southeast conjugate structures. Most of the composite focal mechanisms that we could determine indicate predominantly strike-slip, right-lateral faulting. Our results indicate that most of the seismicity that occurred after the 15 June eruption is related to the east-west regional compressional stress field related to the subduction. We suggest that the regional stress field induces seismicity along new or preexisting faults in the medium surrounding the volcano where the stress field was locally disturbed by the volcanic eruption. Copyright 2004 by the American Geophysical Union.

  11. Leaching characteristics of ash from the May 18, 1980, eruption of Mount St. Helens Volcano, Washington

    USGS Publications Warehouse

    Smith, David Burl; Zielinski, Robert A.; Taylor, Howard E.

    1982-01-01

    Leaching of freshly erupted air-fall ash, unaffected by rain, from the May 18, 1.980,eruption of Mount St. Helens volcano, Washington, shows that Ca 2+, Na+, Mg+, SO4 2-, and Cl- are the predominant chemical species released on first exposure of the ash to water. Extremely high correlation of Ca with SO4 and Na with Cl in water leachates suggests the presence of CaSO4 and NaCl salts on the ash. The amount of water soluble material on ash increases with distance from source and with the weight fraction of small (less than 63 micrometers) ash particles of high-surface area. This suggests that surface reactions such as adsorption are responsible for concentrating the soluble material. CaSO4, NaCl, and other salts are probably formed as microscopic crystals in the high-temperature core of the eruption column and are then adsorbed by silicate ash particles. The environmentally important elements Zn, Cu, Cd, F, Pb, and Ba are released by a water leach in concentrations which could pose short-term hazards to some forms of aquatic life. However, calculated concentrations are based on a water-to-ash ratio of 4:1 or less, which is probably an underestimation of the regionally operative ratio. A subsequent leach of ash by warm alkaline solution shows dramatic increases in the amount of dissolved SiO2, U, and V, which are probably caused by increased dissolution of the glassy component of ash. Glass dissolution by alkaline ground water is a mechanism for providing these three elements to sedimentary traps where they may co-accumulate as uraniferous silica or U-V minerals. Leaching characteristics of ash from Mount St. Helens are comparable to characteristics of ash of similar composition from volcanoes in Guatemala. Ashes from each locality show similar ions predominating for a given leachate and similar fractions of a particular element in the ash removed on contact with the leach solution.

  12. Mount St. Helens: biological responses following the 1980 eruptions — an indexed bibliography and research abstracts (1980 - 93).

    Treesearch

    Peter M. Frenzen; Anne M. Delano

    1994-01-01

    The May 18, 1980, eruption of Mount St. Helens in Washington is possibly the best documented geological event in history. The bibliography displays the results of 13 years of biological and related research in a convenient, indexed format. Our intent is to facilitate collaboration between scientists contemplating new research initiatives and experienced investigators...

  13. Automated Earthquake Detection During the 2004-2005 Eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Moran, S. C.; Qamar, A. I.; Buurman, H. M.

    2005-12-01

    Seismicity associated with the 2004-2005 eruption of Mount St. Helens (MSH) has featured well over 600,000 individual earthquakes. To date only a small fraction have been located by an analyst, and accurate locations for all events will require time-intensive analyst review as well as cross-correlation and relative relocation analyses. In the interim we employed amplitude-based algorithms to detect events on individual stations and track basic event parameters such as inter-event times and peak amplitudes throughout the course of the eruption. The algorithms had to be fine-tuned to accommodate occasional noise glitches and differences in sensor types, and automated picks were reviewed to ensure that the algorithm was correctly discriminating between events and noise. We compiled parameters for several far-field (> 3 km) and near-field (< 1 km) stations that were in operation for variable lengths of time during the eruption. Events detected at far-field stations were dominated by so-called ""drumbeat"" earthquakes that have accompanied the lava-dome-building eruption since mid-October. Through April 2005 these events were an amazingly regular 40-60 seconds apart, and event sizes were also regular. From April 12-19 inter-event times more than doubled and increased in event size, coinciding with a change in the locus of active dome extrusion. From late April through the beginning of September inter-event times increased to over 1000 seconds and became more irregular while event size gradually declined. This coincided with extrusion and break up of the last two lava domes emplaced to date, and the decline in seismicity may reflect a change in system dynamics such as decreasing normal stress or friction along conduit margins. The near-field stations showed no regular inter-event time patterns, as they were sensitive to many small events in addition to the drumbeat events. Plots of peak amplitudes show complexities not seen in the drumbeat earthquakes, such as systematic

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

    USGS Publications Warehouse

    Hoblitt, Richard P.

    1986-01-01

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

  15. The mount st. Helens volcanic eruption of 18 may 1980: large short-term surface temperature effects.

    PubMed

    Robock, A; Mass, C

    1982-05-07

    The surface temperature effects of the 18 May 1980 eruption of Mount St. Helens Volcano were examinedfor 1 day immediately after the eruption; 24-hour temperature differences and Model Output Statistics errors as well as the detailed temporal evolution of surface temperature at selected stations were used. During the daytime hours immediately after the eruption, the temperature was suppressed by the volcanic plume by as much as 8 degrees C. That night, low-level volcanic dust produced temperature enhancements of up to 8 degrees C. These effects quickly diminished the next day as the volcanic dust cloud dissipated and moved toward the east. The net local effect of the eruption appears to be warming, in contrast to cooling which might be expected over climatic time scales.

  16. Hydrometeor-enhanced tephra sedimentation: Constraints from the 18 May 1980 eruption of Mount St. Helens

    USGS Publications Warehouse

    Durant, A.J.; Rose, William I.; Sarna-Wojcicki, A. M.; Carey, Steven; Volentik, A.C.M.

    2009-01-01

    Uncertainty remains on the origin of distal mass deposition maxima observed in many recent tephra fall deposits. In this study the link between ash aggregation and the formation of distal mass deposition maxima is investigated through reanalysis of tephra fallout from the Mount St. Helens 18 May 1980 (MSH80) eruption. In addition, we collate all the data needed to model distal ash sedimentation from the MSH80 eruption cloud. Four particle size subpopulations were present in distal fallout with modes at 2.2 ??, 4.2 ??, 5.9 ??, and 8.3 ??. Settling rates of the coarsest subpopulation closely matched predicted single-particle terminal fall velocities. Sedimentation of particles <100 ??m was greatly enhanced, predominantly through aggregation of a particle subpopulation with modal diameter 5.9 ?? 0.2 ?? (19 ?? 3 ??m). Mammatus on the MSH80 cloud provided a mechanism to transport very fine ash particles, with predicted atmospheric lifetimes of days to weeks, from the upper troposphere to the surface in a matter of hours. In this mechanism, ash particles initiate ice hydrometeor formation high in the troposphere. Subsequently, the volcanic cloud rapidly subsides as mammatus develop from increased particle loading and cloud base sublimation. Rapid fallout occurs as the cloud passes through the melting level in a process analogous to snowflake aggregation. Aggregates sediment en masse and form the distal mass deposition maxima observed in many recent volcanic ash fall deposits. This work provides a data resource that will facilitate tephra sedimentation modeling and allow model intercomparisons. Copyright 2009 by the American Geophysical Union.

  17. Subevents of long-period seismicity during the 2004-2008 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Matoza, R. S.; Chouet, B. A.; Hedlin, M. A.; Garces, M. A.

    2009-12-01

    One of the most striking aspects of seismicity during the 2004-2008 eruption of Mount St. Helens (MSH) was the precise regularity or ‘periodicity’ in occurrence of repetitive long-period (LP) or ‘drumbeat’ events over sustained time periods. However, this periodicity was not always observed, and at times the temporal occurrence of LP events became more random. In addition, accompanying the dominant LP class of events during the 2004-2008 MSH eruption, there was a near-continuous, randomly occurring series of smaller seismic events. These subevents were usually only observable at stations deployed in or close to the MSH crater, i.e., in the immediate vicinity of the LP seismic source region. The subevents are not always simply small-amplitude versions of the dominant LP class of events, but appear instead to result from a separate random process only loosely-coupled to the main LP source mechanism. We present an analysis of the inter-event time and amplitude distributions of the subevents, using waveform cross-correlation to separate LP events from the subevents. We also discuss seismic tremor that accompanied the 8 March 2005 phreatic explosion event at MSH. This tremor consists of a rapid succession of LPs and subevents triggered during the explosion, in addition to broadband noise from the sustained degassing. Immediately afterwards, seismicity returned to the pre-explosion occurrence pattern. This triggering in relation to the rapid ejection of steam from the system, and subsequent return to pre-explosion seismicity, suggest that both seismic event types originated in a region of the subsurface hydrothermal system that was 1) in contact with the reservoir feeding the 8 March 2005 phreatic explosion, but 2) not destroyed or drained by the explosion event.

  18. Structure and physical characteristics of pumice from the climactic eruption of Mount Mazama (Crater Lake), Oregon

    USGS Publications Warehouse

    Klug, C.; Cashman, K.; Bacon, C.

    2002-01-01

    The vesicularity, permeability, and structure of pumice clasts provide insight into conditions of vesiculation and fragmentation during Plinian fall and pyroclastic flow-producing phases of the ???7,700 cal. year B.P. climactic eruption of Mount Mazama (Crater Lake), Oregon. We show that bulk properties (vesicularity and permeability) can be correlated with internal textures and that the clast structure can be related to inferred changes in eruption conditions. The vesicularity of all pumice clasts is 75-88%, with >90% interconnected pore volume. However, pumice clasts from the Plinian fall deposits exhibit a wider vesicularity range and higher volume percentage of interconnected vesicles than do clasts from pyroclastic-flow deposits. Pumice permeabilities also differ between the two clast types, with pumice from the fall deposit having higher minimum permeabilities (???5??10-13 m2) and a narrower permeability range (5-50??10-13 m2) than clasts from pyroclastic-flow deposits (0.2-330??10-13 m2). The observed permeability can be modeled to estimate average vesicle aperture radii of 1-5 ??m for the fall deposit clasts and 0.25-1 ??m for clasts from the pyroclastic flows. High vesicle number densities (???109 cm-3) in all clasts suggest that bubble nucleation occured rapidly and at high supersaturations. Post-nucleation modifications to bubble populations include both bubble growth and coalescence. A single stage of bubble nucleation and growth can account for 35-60% of the vesicle population in clasts from the fall deposits, and 65-80% in pumice from pyroclastic flows. Large vesicles form a separate population which defines a power law distribution with fractal dimension D=3.3 (range 3.0-3.5). The large D.value, coupled with textural evidence, suggests that the large vesicles formed primarily by coalescence. When viewed together, the bulk properties (vesicularity, permeability) and textural characteristics of all clasts indicate rapid bubble nucleation followed by

  19. 40Ar/39Ar dating of the eruptive history of Mount Erebus, Antarctica: Summit flows, tephra, and caldera collapse

    USGS Publications Warehouse

    Harpel, C.J.; Kyle, P.R.; Esser, R.P.; McIntosh, W.C.; Caldwell, D.A.

    2004-01-01

    Eruptive activity has occurred in the summit region of Mount Erebus over the last 95 ky, and has included numerous lava flows and small explosive eruptions, at least one plinian eruption, and at least one and probably two caldera-forming events. Furnace and laser step-heating 40Ar/39Ar ages have been determined for 16 summit lava flows and three englacial tephra layers erupted from Mount Erebus. The summit region is composed of at least one or possibly two superimposed calderas that have been filled by post-caldera lava flows ranging in age from 17 ?? 8 to 1 ?? 5 ka. Dated pre-caldera summit flows display two age populations at 95 ?? 9 to 76 ?? 4 ka and 27 ?? 3 to 21 ??4 ka of samples with tephriphonolite and phonolite compositions, respectively. A caldera-collapse event occurred between 25 and 11 ka. An older caldera-collapse event is likely to have occurred between 80 and 24 ka. Two englacial tephra layers from the flanks of Mount Erebus have been dated at 71 ?? 5 and 15 ?? 4 ka. These layers stratigraphically bracket 14 undated tephra layers, and predate 19 undated tephra layers, indicating that small-scale explosive activity has occurred throughout the late Pleistocene and Holocene eruptive history of Mount Erebus. A distal, englacial plinian-fall tephra sample has an age of 39 ?? 6 ka and may have been associated with the older of the two caldera-collapse events. A shift in magma composition from tephriphonolite to phonolite occurred at around 36 ka. ?? Springer-Verlag 2004.

  20. Source mechanisms of persistent shallow earthquakes during eruptive and non-eruptive periods between 1981 and 2011 at Mount St. Helens, Washington

    USGS Publications Warehouse

    Lehto, Heather L.; Roman, Diana C.; Moran, Seth C.

    2013-01-01

    Shallow seismicity between 0 and 3-km depth has persisted at Mount St. Helens, Washington (MSH) during both eruptive and non-eruptive periods for at least the past thirty years. In this study we investigate the source mechanisms of shallow volcano-tectonic (VT) earthquakes at MSH by calculating high-quality hypocenter locations and fault plane solutions (FPS) for all VT events recorded during two eruptive periods (1981–1986 and 2004–2008) and two non-eruptive periods (1987–2004 and 2008–2011). FPS show a mixture of normal, reverse, and strike-slip faulting during all periods, with a sharp increase in strike-slip faulting observed in 1987–1997 and an increase in normal faulting in 1998–2004. FPS P-axis orientations show a ~ 90° rotation with respect to regional σ1 (N23°E) during 1981–1986 and 2004–2008, bimodal orientations (~ N-S and ~ E-W) during 1987–2004, and bimodal orientations at ~ N-E and ~ S-W from 2008–2011. We interpret these orientations to likely be due to pressurization accompanying the shallow intrusion and subsequent eruption of magma as domes during 1981–1986 and 2004–2008 and the buildup of pore pressure beneath a seismogenic volume (located at 0–1 km) with a smaller component due to the buildup of tectonic forces during 1987–2004 and 2008–2011.

  1. Mount St. Helens a decade after the 1980 eruptions: magmatic models, chemical cycles, and a revised hazards assessment

    USGS Publications Warehouse

    Pallister, J.S.; Hoblitt, R.P.; Crandell, D.R.; Mullineaux, D.R.

    1992-01-01

    Available geophysical and geologic data provide a simplified model of the current magmatic plumbing system of Mount St. Helens (MSH). This model and new geochemical data are the basis for the revised hazards assessment presented here. The assessment is weighted by the style of eruptions and the chemistry of magmas erupted during the past 500 years, the interval for which the most detailed stratigraphic and geochemical data are available. This interval includes the Kalama (A. D. 1480-1770s?), Goat Rocks (A.D. 1800-1857), and current eruptive periods. In each of these periods, silica content decreased, then increased. The Kalama is a large amplitude chemical cycle (SiO2: 57%-67%), produced by mixing of arc dacite, which is depleted in high field-strength and incompatible elements, with enriched (OIB-like) basalt. The Goat Rocks and current cycles are of small amplitude (SiO2: 61%-64% and 62%-65%) and are related to the fluid dynamics of magma withdrawal from a zoned reservoir. The cyclic behavior is used to forecast future activity. The 1980-1986 chemical cycle, and consequently the current eruptive period, appears to be virtually complete. This inference is supported by the progressively decreasing volumes and volatile contents of magma erupted since 1980, both changes that suggest a decreasing potential for a major explosive eruption in the near future. However, recent changes in seismicity and a series of small gas-release explosions (beginning in late 1989 and accompanied by eruption of a minor fraction of relatively low-silica tephra on 6 January and 5 November 1990) suggest that the current eruptive period may continue to produce small explosions and that a small amount of magma may still be present within the conduit. The gas-release explosions occur without warning and pose a continuing hazard, especially in the crater area. An eruption as large or larger than that of 18 May 1980 (???0.5 km3 dense-rock equivalent) probably will occur only if magma rises from

  2. Precursor gases of aerosols in the Mount St. Helens eruption plumes at stratospheric altitudes

    NASA Astrophysics Data System (ADS)

    Inn, E. C. Y.; Vedder, J. F.; Condon, E. P.; Ohara, D.

    1982-10-01

    Nineteen stratospheric samples from the eruption plumes of Mount St. Helens were collected in five flight experiments. The plume samples were collected at various altitudes from 13.1 to 20.7 km by using the Ames cryogenic sampling system on board the NASA U-2 aircraft. The enriched, cryogenically collected samples were analyzed by chromatography. The concentrations of aerosols precursor gases (OCS, SO2, and CS2), CH3Cl, N2O, CF2Cl2, and CFCl3 were measured by gas chromatography. Large enhancement of the mixing ratio of SO2 and moderate enhancement of CS2 and OCS were found in the plume samples compared with similar measurement under pre-volcanic conditions. A fast decay rate of the SO2 mixing ratio in the plume was observed. Measurement of Cl(-), SO2(2-), and NO3(-) by ion chromatography was also carried out on water solutions prepared from the plume samples. The results obtained with this technique imply large mixing ratios of HCl, (NO + NO2 + HNO3), and SO2, in which these constituents are the respective sources of the anions. Measurement of the Rn222 concentration in the plume was made. Other stratospheric constituents in the plume samples, such as H2O, CO2, CH4, and CO, were also observed.

  3. Mount st. Helens ash from the 18 may 1980 eruption: chemical, physical, mineralogical, and biological properties.

    PubMed

    Fruchter, J S; Robertson, D E; Evans, J C; Olsen, K B; Lepel, E A; Laul, J C; Abel, K H; Sanders, R W; Jackson, P O; Wogman, N S; Perkins, R W; VAN Tuyl, H H; Beauchamp, R H; Shade, J W; Daniel, J L; Erikson, R L; Sehmel, G A; Lee, R N; Robinson, A V; Moss, O R; Briant, J K; Cannon, W C

    1980-09-05

    Samples of ash from the 18 May 1980 eruption of Mount St. Helens were collected from several locations in eastern Washington and Montana. The ash was subjected to a variety of analyses to determine its chemical, physical, mineralogical, and biological characteristics. Chemically, the ash samples were of dacitic composition. Particle size data showed bimodal distributions and differed considerably with location. However, all samples contained comparable amounts of particles less than 3.5 micrometers in diameter (respirable fraction). Mineralogically, the samples ranged from almost totally glassy to almost totally crystalline. Crystalline samples were dominated by plagioclase feldspar (andesine) and orthopyroxene (hypersthene), with smaller amounts of titanomagnetite and hornblende. All but one of the samples contained from less than 1 percent to 3 percent free crystalline silica (quartz, trydimite, or cristobalite) in both the bulk samples and 1 to 2 percent in the fractions smaller than 3.5 micrometers. The long-lived natural radionuclide content of the ash was comparable to that of crustal material; however, relatively large concentrations of short-lived radon daughters were present and polonium-210 content was inversely correlated with particle size. In vitro biological tests showed the ash to be nontoxic to alveolar macrophages, which are an important part of the lungs' natural clearance mechanism. On the basis of a substantial body of data that has shown a correlation between macrophage cytotoxicity and fibrogenicity of minerals, the ash is not predicted to be highly fibrogenic.

  4. Aircraft sampling of the sulfate layer near the tropopause following the eruption of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Lezberg, E. A.; Otterson, D. A.; Roberts, W. K.; Papathakos, L. C.

    1982-01-01

    Twenty-three filter sampling flights of the NASA Lewis F-106 aircraft, were conducted in the Great Lakes region between June 4 and Dec. 23, 1980, following the major eruption of Mount St. Helens on May 18. The IPC-1478 filters were exposed over an altitude range spanning the local tropopause. A filter sample exposed above the tropopause on June 5 indicated a sulfate level 50 times the baseline measurements, which is consistent with the trajectory predictions of the leading edge of the cloud on its second transit around the earth. Subsequent measurements over a period of 7 months revealed the existence of a layer of sulfate above the tropopause that decayed to a level of about 4 times previously measured background levels by the beginning of August. Concentration of nitrate above the tropopause exhibited considerable variability and showed some enhancement compared with previously measured concentration levels. On the basis of the null results of X ray fluorescence measurements, there is no evidence of ash particle concentrations of greater than 3.4 microns/cu m persisting in the layer above the tropopause following the second transit of the cloud.

  5. Precursor gases of aerosols in the Mount St. Helens eruption plumes at stratospheric altitudes

    NASA Technical Reports Server (NTRS)

    Inn, E. C. Y.; Vedder, J. F.; Condon, E. P.; Ohara, D.

    1982-01-01

    Nineteen stratospheric samples from the eruption plumes of Mount St. Helens were collected in five flight experiments. The plume samples were collected at various altitudes from 13.1 to 20.7 km by using the Ames cryogenic sampling system on board the NASA U-2 aircraft. The enriched, cryogenically collected samples were analyzed by chromatography. The concentrations of aerosols precursor gases (OCS, SO2, and CS2), CH3Cl, N2O, CF2Cl2, and CFCl3 were measured by gas chromatography. Large enhancement of the mixing ratio of SO2 and moderate enhancement of CS2 and OCS were found in the plume samples compared with similar measurement under pre-volcanic conditions. A fast decay rate of the SO2 mixing ratio in the plume was observed. Measurement of Cl(-), SO2(2-), and NO3(-) by ion chromatography was also carried out on water solutions prepared from the plume samples. The results obtained with this technique imply large mixing ratios of HCl, (NO + NO2 + HNO3), and SO2, in which these constituents are the respective sources of the anions. Measurement of the Rn222 concentration in the plume was made. Other stratospheric constituents in the plume samples, such as H2O, CO2, CH4, and CO, were also observed.

  6. Aircraft sampling of the sulfate layer near the tropopause following the eruption of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Lezberg, E. A.; Otterson, D. A.; Roberts, W. K.; Papathakos, L. C.

    1982-01-01

    Twenty filter sampling flights of the NASA Lewis F-106 aircraft were conducted in the Great Lakes region between June 4 and August 8, 1980, following the major eruption of Mount St. Helens, Washington on May 18. The IPC-1478 filters were exposed over an altitude range spanning the local tropopause. Quarter sections were analyzed for sulfate and nitrate by ion chromatography and selected samples were analyzed for chloride by selective ion electrode. Trace elements were searched by X-ray fluorescence analysis. A filter sample taken above the tropopause on June 5 indicated a sulfate level of 50 times the baseline measurements. Subsequent measurements over a period of 2 months showed an initial dropoff and formation of a persistent layer of sulfate above the tropopause with a concentration of 10 to 18 times previously measured background-levels. Concentrations of nitrate above the tropopause exhibited considerable variability and some enhancement compared with previously measured concentration levels. It is suggested that the source of the nitrate may also be volcanic as evidenced by its temporal relationship to the sulfate concentration changes. Based on the null results of X-ray fluorescence measurements, there is no evidence of ash particle concentrations greater than 3.4 microns g/cubic m persisting in the layer above the tropopause after the second transit of the cloud.

  7. The December 2015 Mount Etna eruption: An analysis of inflation/deflation phases and faulting processes

    NASA Astrophysics Data System (ADS)

    Aloisi, Marco; Jin, Shuanggen; Pulvirenti, Fabio; Scaltrito, Antonio

    2017-06-01

    During the first days of December 2015, there were four paroxysmal events at the ;Voragine; crater on Mount Etna, which were among the most violent observed during the last two decades. A few days after the ;Voragine; paroxysms, the Pernicana - Provenzana fault system, located near the crater area, underwent an intense seismic swarm with a maximum ;local; magnitude ML of 3.6. This paper investigates the relationship between the eruptive phenomenon and the faulting process in terms of Coulomb stress changes. The recorded seismicity is compatible with a multicausal stress redistribution inside the volcano edifice, occurring after the four paroxysmal episodes that interrupted the usual trend of inflation observed at Mt. Etna. The recorded seismicity falls within the framework of a complex chain of various and intercorrelated processes that started with the inflation preparing the ;Voragine; magmatic activity. This was followed with the rapid deflation of the volcano edifice during the paroxysmal episodes. We determined that the recorded deflation was not the direct cause of the seismic swarm. In fact, the associated Coulomb stress change, in the area of seismic swarm, was of about -1 [bar]. Instead, the fast deflation caused the rarely observed inversion of dislocation in the eastern flank at the same time as intense hydrothermal activity that, consequently, underwent an alteration. This process probably reduced the friction along the fault system. Then, the new phase of inflation, observed at the end of the magmatic activity, triggered the faulting processes.

  8. Fluvial sediment transport and deposition following the 1991 eruption of Mount Pinatubo

    USGS Publications Warehouse

    Hayes, S.K.; Montgomery, D.R.; Newhall, C.G.

    2002-01-01

    The 1991 eruption of Mount Pinatubo generated extreme sediment yields from watersheds heavily impacted by pyroclastic flows. Bedload sampling in the Pasig-Potrero River, one of the most heavily impacted rivers, revealed negligible critical shear stress and very high transport rates that reflected an essentially unlimited sediment supply and the enhanced mobility of particles moving over a smooth, fine-grained bed. Dimensionless bedload transport rates in the Pasig-Potrero River differed substantially from those previously reported for rivers in temperate regions for the same dimensionless shear stress, but were similar to rates identified in rivers on other volcanoes and ephemeral streams in arid environments. The similarity between volcanically disturbed and arid rivers appears to arise from the lack of an armored bed surface due to very high relative sediment supply; in arid rivers, this is attributed to a flashy hydrograph, whereas volcanically disturbed rivers lack armoring due to sustained high rates of sediment delivery. This work suggests that the increases in sediment supply accompanying massive disturbance induce morphologic and hydrologic changes that temporarily enhance transport efficiency until the watershed recovers and sediment supply is reduced. ?? 2002 Elsevier Science B.V. All rights reserved.

  9. Database for geologic maps of pyroclastic-flow and related deposits of the 1980 eruptions of Mount St. Helens, Washington

    USGS Publications Warehouse

    Furze, Andrew J.; Bard, Joseph A.; Robinson, Joel; Ramsey, David W.; Kuntz, Mel A.; Rowley, Peter D.; MacLeod, Norman S.

    2017-10-31

    This publication releases digital versions of the geologic maps in U.S. Geological Survey Miscellaneous Investigations Map 1950 (USGS I-1950), “Geologic maps of pyroclastic-flow and related deposits of the 1980 eruptions of Mount St. Helens, Washington” (Kuntz, Rowley, and MacLeod, 1990) (https://pubs.er.usgs.gov/publication/i1950). The 1980 Mount St. Helens eruptions on May 18, May 25, June 12, July 22, August 7, and October 16–18 produced pyroclastic-flow and related deposits. The distribution and morphology of these deposits, as determined from extensive field studies and examination of vertical aerial photographs, are shown on four maps in I-1950 (maps A–D) on two map sheets. Map A shows the May 18, May 25, and June 12 deposits; map B shows the July 22 deposits; map C shows the August 7 deposits; and map D shows the October 16–18 deposits. No digital geospatial versions of the geologic data were made available at the time of publication of the original maps. This data release consists of attributed vector features, data tables, and the cropped and georeferenced scans from which the features were digitized, in order to enable visualization and analysis of these data in GIS software. This data release enables users to digitally re-create the maps and description of map units of USGS I-1950; map sheet 1 includes text sections (Introduction, Physiography of Mount St. Helens at the time of the 1980 eruptions, Processes of the 1980 eruptions, Deposits of the 1980 eruptions, Limitations of the maps, Preparation of the maps, and References cited) and associated tables and figures that are not included in this data release.

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

    USGS Publications Warehouse

    Frenzen, Peter M.; Matarrese, Michael T.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

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

  11. Mount St Helens eruptions, May 18 to June 12, 1980. An overview of the acute health impact.

    PubMed

    Baxter, P J; Ing, R; Falk, H; French, J; Stein, G F; Bernstein, R S; Merchant, J A; Allard, J

    1981-12-04

    Thirty-five known deaths were caused by the landslide and lateral blast of the May 18 eruption of Mount St Helens and at least 23 persons are missing. In 18 of 23 cases that reached autopsy, asphyxiation from ash inhalation was the cause of death. A rapidly established hospital surveillance system detected increases in the number of emergency room (ER) visits and admissions for asthma and bronchitis in communities with the heaviest ashfall after the May 18 eruption and the eruptions on May 25 and June 12. There were also increases in the number of ER visits for ash-related eye complaints in some areas. laboratory studies indicated that the May 18 ash was not acutely toxic, but the respirable portion contained 3% to 7% of crystalline free silica, a potential pneumoconiosis hazard to certain heavily exposed occupational groups. Continuing volcanic activity of Mount St Helens and future eruption of other volcanoes in the Cascade Range may pose a variety of health hazards, including blast, ashfalls, flooding, damage to public utilities, and possible psychosocial effects.

  12. Chronology, morphology and stratigraphy of pumiceous pyroclastic-flow (ignimbrite) deposits from the eruption of Mount St. Helens on 18 May 1983

    NASA Technical Reports Server (NTRS)

    Criswell, C. W.; Elston, W. E.

    1984-01-01

    Between 1217 and 1620 hours (PDT), on May 18, 1980, the magmatic eruption column of Mount St. Helens formed an ash fountain and pyroclastic flows dominated the eruption process over tephra ejection. Eurption-rate pulsations generally increased to a maximum at 1600 to 1700 hrs. After 1620 hrs, the eruption assumed an open-vent discharge with strong, vertical ejection of tephra. Relative eruption rates (relative mass flux rates) of the pyroclastic flows were determined by correlating sequential photographs and SLAR images, obtained during the eruption, with stratigraphy and surface morphology of the deposits.

  13. Measuring the Dome Growth of the 2004-2005 Eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Schilling, S. P.; Denlinger, R.; Thompson, R. A.; Messerich, J.

    2005-12-01

    In October 2004, a new period of dome growth began that changed the topography of the 1980 crater at Mount St. Helens dramatically. From October 2004 through July 2005, nearly 60 million cubic meters of lava extruded onto the crater floor immediately south of the 1980-1986 lava dome. The eruption intensely deformed and divided the crater glacier on this floor. It created spectacular crevassing and rapid advance of the east arm of the glacier then caused crevassing and broad uplift of the glacier's west arm. Time-sequential vertical aerial photography documents morphologic change and enabled construction of a series of 13 2-m-resolution digital elevation models (DEMs) for the period between October 4, 2004 and July 14, 2005. Vertical aerial photographs flown at a nominal 1:12000 scale were acquired at three-week intervals, scanned at 12-micron resolution, and rectified using a soft-copy (i.e., digital image) photogrammetric workstation. Aerotriangulated models were constructed using ground control outside the area of active deformation, derived from pre-eruption GPS and photogrammetric data, and passed to subsequent model sets. Resulting location accuracy is on the order of decimeters. The DEM data allow us to estimate dome volumes during growth. To extract volumetric changes and calculate extrusion rates, each DEM surface was compared to pre-eruption reference surfaces from 2000 and 2003, as well as to the preceding DEM surface. On July 14, 2005, the new dome was approximately 700 m long (NW-SE) and 560 m wide (SW-NE). The volume of the new dome (including talus), was about 58 million cubic meters, approximately two-thirds the volume of the 1980-1986 dome. The volumetric growth rate in 2004-2005 ranged from a maximum of 9 m3/sec in the early stages of growth to an average of 1-3 m3/sec thereafter. The DEMs also are used to quantify dome height variations, size of the conduit opening, and the mechanics of dome emplacement (growth and collapse) as well as deformation

  14. Constraints on Eruption Dynamics, Mount St. Helens, WA, 2004-2008

    NASA Astrophysics Data System (ADS)

    Schneider, A.; Rempel, A. W.; Cashman, K. V.

    2009-12-01

    Different models have been proposed for the “drumbeat” earthquakes that accompanied recent eruptive behavior at Mount St. Helens. Debate continues as to whether seismicity is related to brittle failure during the extrusion of solid dacite spines, or is the result of hydrothermal fluids interacting with a crack buried in the volcanic edifice. The thermomechanical properties at the interface between conduit magma and the solid plug play a central role in governing the extrusive behavior. To constrain predictions of conditions at this interface, we model the three-phase magma transport from chamber to plug using pMELTS to account for partial crystallization caused by gas exsolution and degassing during ascent. The model predicts that magma compressibility beneath the plug is lower than necessary to release accommodated elastic strain at intervals that match the periods of the drumbeat earthquakes. While our results are not consistent with episodic whole-plug slip, they may nevertheless be compatible with stick-slip behavior on discrete patches of the bounding fault. We supplement our conduit modeling with a quantitative examination of the roughness of slip surfaces. Power spectral analysis of high-resolution digital elevation models yield a power-law relationship, that is similar to results from tectonic faults that have experienced only limited (typically less than 1 meter) amounts of slip. Structural evidence for expansion at different scales may indicate high-temperature deformation near the brittle-ductile transition. Our results suggest that simultaneous magma fracture and expansion may have generated key seismic characteristics including the observed dilatational first motions and moment magnitude-corner frequency scaling consistent with brittle tectonic faults.

  15. Using An Extensive Catalogue of Repeatable Strombolian Eruptions to Monitor Small Medium Changes at Mount Erebus Volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Henderson, B.; Aster, R. C.; Kyle, P.

    2005-12-01

    A recent study by Gret et al. (2005) reconfirmed earlier work demonstrating remarkable, though variable, repeatability of short-period seismic signals produced by characteristic Strombolian eruptions of Mount Erebus. The eruptions originate as impulsive explosions of large simple gas bubbles from the surface of a long-lived, actively convecting phonolitic lava lake that rapidly refills afterwards. This self-reconstructing eruptive system lends itself to highly repeatable seismic sources. Gret et al. further noted that these repeatable seismograms (extending many 10s of seconds into the coda) and associated seismic energy scattered within the low-velocity waveguide of the volcano conduit might facilitate the novel tracking of small temporal changes in seismic velocity and/or impedance contrast within the near summit magma body and more general conduit system. We expand on this suggestive work using comprehensive correlation-based similar seismogram analysis of an extensive database of over 3000 candidate Strombolian eruptions occurring between Jan 1992 and July 2005, and recorded at up to 9 different seismic stations situated around the volcano. To obviate potential complications caused by nonlinear response (e.g., clipping) at short-period instruments, we incorporate data from broadband, high-dynamic range sensors and digital telemetry installed since 2001, and take advantage of a new period of prolific eruptions, especially since early 2005, Gret, A., Snieder, R., Aster, R., Kyle, P., Monitoring rapid temporal change in a volcano with coda wave interferometry, Geop. Res. Lett., 32, L06304, doi:10.1029/2004GL021143, 2005.

  16. Morphological analysis of active Mount Nemrut stratovolcano, eastern Turkey: evidences and possible impact areas of future eruption

    NASA Astrophysics Data System (ADS)

    Aydar, Erkan; Gourgaud, Alain; Ulusoy, Inan; Digonnet, Fabrice; Labazuy, Philippe; Sen, Erdal; Bayhan, Hasan; Kurttas, Turker; Tolluoglu, Arif Umit

    2003-05-01

    Mount Nemrut, an active stratovolcano in eastern Turkey, is a great danger for its vicinity. The volcano possesses a summit caldera which cuts the volcano into two stages, i.e. pre- and post-caldera. Wisps of smoke and hot springs are to be found within the caldera. Although the last recorded volcanic activity is known to have been in 1441, we consider here that the last eruption of Nemrut occurred more recently, probably just before 1597. The present active tectonic regime, historical eruptions, occurrence of mantle-derived magmatic gases and the fumarole and hot spring activities on the caldera floor make Nemrut Volcano a real danger for its vicinity. According to the volcanological past of Nemrut, the styles of expected eruptions are well-focused on two types: (1) occurrence of water within the caldera leads to phreatomagmatic (highly energetic) eruptions, subsequently followed by lava extrusions, and (2) effusions-extrusions (non-explosive or weakly energetic eruptions) on the flanks from fissures. To predict the impact area of future eruptions, a series of morphological analyses based on field observations, Digital Elevation Model and satellite images were realized. Twenty-two valleys (main transport pathways) were classified according to their importance, and the physical parameters related to the valleys were determined. The slope values in each point of the flanks and the Heim parameters H/ L were calculated. In the light of morphological analysis the possible impact areas around the volcano and danger zones were proposed. The possible transport pathways of the products of expected volcanic events are unified in three main directions: Bitlis, Guroymak, Tatvan and Ahlat cities, the about 135 000 inhabitants of which could be threatened by future eruptions of this poorly known and unsurveyed volcano.

  17. Comparison of Mount Saint Helens Volcanic Eruption to a Nuclear Explosion.

    DTIC Science & Technology

    1981-01-01

    In addition, the ash from each eruption is reported to have different properties, depending on the gas - richness of the magma and other factors. Ash...deposition of the large quantities of ash ejected. Six months after the first violent eruption , entry to the area within 20 miles of the volcano was... eruption was pyroclastic flows, relatively dense gas -laden flows of rock fragments. The gases appear to act like a lubricant, permitting the debris to

  18. Initial assessment of the stratospheric and climatic impact of the 1991 Mount Pinatubo eruption - Prologue

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.

    1992-01-01

    An overview is given of the techniques employed to evaluate the early effects of the volcanic eruption on the stratosphere and climate, and data are given on the initial eruption yield. Global satellite measurements were taken by TOMS, SAGE II, AVHRR, and other devices, and the initial results indicate an eruption yield of 20 megatons of SO2 and 20-30 megatons of H2SO4/H2O aerosol mass. The predicted effects of the eruption - accelerated global ozone depletion and surface cooling - can be compared to meteorological data to test the validity of present climate models based on these data.

  19. Lava identification by paleomagnetism: a case study and some problems surrounding the 1631 eruption of Mount Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Conte-Fasano, G.; Urrutia-Fucugauchi, J.; Goguitchaichvili, A.; Incoronato, A.; Tiano, P.

    2006-08-01

    Detailed rock magnetic, paleomagnetic and absolute paleointensity studies of lava flows from the disputed 1631 Mount Vesuvius eruption are reported. The magnetic carrier consists of pseudo-single domain state Ti-poor titanomagnetites. Characteristic magnetization directions determined from detailed stepwise alternating field and thermal demagnetizations provide four new well-defined flow unit mean directions, with α95 ranging from 0.7° to 2.6°. Paleodirections for 11 lava flows from 24-four flows studied previously appear to be related to the 1631 eruption, as indicated by their correlation to the early 17th century segment of the Italian paleosecular variation reference curve. This provides new evidence supporting the conclusion that the 1631 episode was an explosive-effusive eruption. The paleointensity results obtained from this study are the first to be published for Mount Vesuvius, with virtual dipole moments of 9.24±1.8×1022 and 13.5±0.4×1022 Am2 higher than the present-day geomagnetic field strength.

  20. Mts. Agung and Batur, Bali, Shaded Relief and Colored Height

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This perspective view shows the major volcanic group of Bali, one 13,000 islands comprising the nation of Indonesia. The conical mountain to the left is Gunung Agung, at 3,148 meters (10,308 feet) the highest point on Bali and an object of great significance in Balinese religion and culture. Agung underwent a major eruption in 1963 after more than 100 years of dormancy, resulting in the loss of over 1,000 lives.

    In the center is the complex structure of Batur volcano, showing a caldera (volcanic crater) left over from a massive catastrophic eruption about 30,000 years ago. Judging from the total volume of the outer crater and the volcano, that once lay above it, approximately 140 cubic kilometers(33.4 cubic miles) of material must have been produced by this eruption, making it one of the largest known volcanic events on Earth. Batur is still active and has erupted at least 22 times since the 1800's.

    Two visualization methods were combined to produce the image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the northwest-southeast direction, so that northwest slopes appear bright and southeast slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations.

    Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA

  1. 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.

  2. After the disaster: the hydrogeomorphic, ecological, and biological responses to the 1980 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Major, Jon J.; Crisafulli, Charlie; Bishop, John

    2009-01-01

    The 1980 eruption of Mount St. Helens caused instantaneous landscape disturbance on a grand scale. On 18 May 1980, an ensemble of volcanic processes, including a debris avalanche, a directed pyroclastic density current, voluminous lahars, and widespread tephra fall, abruptly altered landscape hydrology and geomorphology, and created distinctive disturbance zones having varying impacts on regional biota. Response to the geological and ecological disturbances has been varied and complex. In general, eruption-induced alterations in landscape hydrology and geomorphology led to enhanced stormflow discharge and sediment transport. Although the hydrological response to landscape perturbation has diminished, enhanced sediment transport persists in some basins. In the nearly 30 years since the eruption, 350 million (metric) tons of suspended sediment has been delivered from the Toutle River watershed to the Cowlitz River (roughly 40 times the average annual preeruption suspended-sediment discharge of the Columbia River). Such prodigious sediment loading has wreaked considerable socioeconomic havoc, causing significant channel aggradation and loss of flood conveyance capacity. Significant and ongoing engineering efforts have been required to mitigate these problems. The overall biological evolution of the eruption-impacted landscape can be viewed in terms of a framework of survivor legacies. Despite appearances to the contrary, a surprising number of species survived the eruption, even in the most heavily devastated areas. With time, survivor “hotspots” have coalesced into larger patches, and have served as stepping stones for immigrant colonization. The importance of biological legacies will diminish with time, but the intertwined trajectories of geophysical and biological successions will influence the geological and biological responses to the 1980 eruption for decades to come.

  3. Overview of seismicity associated with the 2004-2005 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Moran, S. C.; Malone, S. D.; Qamar, A. I.; Thelen, W.; Waite, G.; Horton, S.; Lahusen, R. G.; Major, J. J.

    2005-12-01

    Following 18 years of quiescence, an earthquake swarm on September 23, 2004, heralded the reawakening of Mount St. Helens (MSH). Seismicity during the 18-year quiescence consisted of shallow (< 3 km) and deep (3-10 km) volcano-tectonic (VT) earthquakes, with the deeper earthquakes occurring mostly during several extended periods of elevated seismicity that likely reflected intrusions of new magma. The swarm on September 23 intensified in a step-wise manner over the first week, and by the first phreatic explosion on October 1 earthquakes had increased significantly in size (Mmax = 3.5) and rate (1-2 per minute). The earthquakes also became shallower (< 1 km) and transitioned from VT to hybrid in character. Following a final phreatic explosion on October 5 earthquake magnitudes and rates decreased significantly. One of the remarkable aspects of MSH seismicity has been the occurrence of repetitive (in waveform) and regular (in time) shallow "drumbeat"" hybrid earthquakes that began in mid-October as lava dome extrusion commenced. With a few exceptions drumbeats occurred roughly every 40-60 seconds through April 2005 before progressively increasing to over 1000 seconds by mid-August. They occurred in association with extrusion of a fault-gouge-covered lava dome that emerged at a relatively constant rate, a linkage that strongly suggests a stick-slip origin for the drumbeats. The increase in inter-event times does not appear to directly correlate with decreasing extrusion rate, suggesting that dome extrusion has become increasingly aseismic over time. Another remarkable aspect is the occurrence of shallow "big"" earthquakes (M 2.5-3.5) starting in mid-November in association with the breakup of the first erupted dome. To date there have been over 250 of these events that have occurred in four temporally-defined groups, most associated with periods when extruded domes were breaking apart. Roughly half have impulsive arrivals, and many of these have dominantly down first

  4. Chlorine as a geobarometer for alkaline magmas: Evidence from a systematic study of the eruptions of Mount Somma-Vesuvius

    NASA Astrophysics Data System (ADS)

    Balcone-Boissard, H.; Boudon, G.; Cioni, R.; Webster, J. D.; Zdanowicz, G.; Orsi, G.; Civetta, L.

    2016-02-01

    Defining the magma storage conditions of a volcanic system is a major goal in modern volcanology due to its direct implications for the style of a possible eruption, and thus on the associated risk of any crisis and the necessary management and mitigation strategies. Below 200 MPa and at equivalent depths, the strongly non-ideal behaviour of the H-C-O-S-Cl-F system in the silicate melt causes unmixing of the fluid phase to form an H2O-rich vapour and a hydrosaline phase in equilibrium with the silicate melt, both responsible for buffering the chlorine (Cl) concentration. Following this equilibrium, the Cl concentration in melts may be used as a geobarometer for alkaline magmas. Systematic application of this method to the main explosive eruptions of Mount Somma-Vesuvius highlights two main magma ponding zones, at ~180-200 and ~100 MPa. At these pressures, the maximum pre-eruptive H2O contents for the different magma compositions can be estimated; the results obtained, largely in agreement with the current literature, therefore confirm the validity of the method. The Cl geobarometer may help scientists to define the variation of the magmatic reservoir location through time and thus provide strong constraints on pre-eruptive conditions, which are of utmost importance for volcanic crisis management.

  5. Chlorine as a geobarometer for alkaline magmas: Evidence from a systematic study of the eruptions of Mount Somma-Vesuvius.

    PubMed

    Balcone-Boissard, H; Boudon, G; Cioni, R; Webster, J D; Zdanowicz, G; Orsi, G; Civetta, L

    2016-02-18

    Defining the magma storage conditions of a volcanic system is a major goal in modern volcanology due to its direct implications for the style of a possible eruption, and thus on the associated risk of any crisis and the necessary management and mitigation strategies. Below 200 MPa and at equivalent depths, the strongly non-ideal behaviour of the H-C-O-S-Cl-F system in the silicate melt causes unmixing of the fluid phase to form an H2O-rich vapour and a hydrosaline phase in equilibrium with the silicate melt, both responsible for buffering the chlorine (Cl) concentration. Following this equilibrium, the Cl concentration in melts may be used as a geobarometer for alkaline magmas. Systematic application of this method to the main explosive eruptions of Mount Somma-Vesuvius highlights two main magma ponding zones, at ~180-200 and ~100 MPa. At these pressures, the maximum pre-eruptive H2O contents for the different magma compositions can be estimated; the results obtained, largely in agreement with the current literature, therefore confirm the validity of the method. The Cl geobarometer may help scientists to define the variation of the magmatic reservoir location through time and thus provide strong constraints on pre-eruptive conditions, which are of utmost importance for volcanic crisis management.

  6. Chlorine as a geobarometer for alkaline magmas: Evidence from a systematic study of the eruptions of Mount Somma-Vesuvius

    PubMed Central

    Balcone-Boissard, H.; Boudon, G.; Cioni, R.; Webster, J. D.; Zdanowicz, G.; Orsi, G.; Civetta, L.

    2016-01-01

    Defining the magma storage conditions of a volcanic system is a major goal in modern volcanology due to its direct implications for the style of a possible eruption, and thus on the associated risk of any crisis and the necessary management and mitigation strategies. Below 200 MPa and at equivalent depths, the strongly non-ideal behaviour of the H-C-O-S-Cl-F system in the silicate melt causes unmixing of the fluid phase to form an H2O-rich vapour and a hydrosaline phase in equilibrium with the silicate melt, both responsible for buffering the chlorine (Cl) concentration. Following this equilibrium, the Cl concentration in melts may be used as a geobarometer for alkaline magmas. Systematic application of this method to the main explosive eruptions of Mount Somma-Vesuvius highlights two main magma ponding zones, at ~180–200 and ~100 MPa. At these pressures, the maximum pre-eruptive H2O contents for the different magma compositions can be estimated; the results obtained, largely in agreement with the current literature, therefore confirm the validity of the method. The Cl geobarometer may help scientists to define the variation of the magmatic reservoir location through time and thus provide strong constraints on pre-eruptive conditions, which are of utmost importance for volcanic crisis management. PMID:26888358

  7. the sub-Plinian Greenish Pumice eruption (19,065±105 yr cal BP) of Mount Somma - Vesuvius. Geochemical and textural constrains.

    NASA Astrophysics Data System (ADS)

    Zdanowicz, Géraldine; Boudon, Georges; Balcone-Boissard, Hélène; Cioni, Raffaello; Mundula, Filippo; Orsi, Giovanni; Civetta, Lucia

    2016-04-01

    Researches are currently focused on large intensity and stable eruptive columns as for Plinian event. But the large variability in deposits issued from sub-Plinian eruptions needs more observations, theoretical and experimental investigations to be better described and enhances criteria of classification and the knowledge on processes at the origin of this unsteadiness of various timescales. Here, we focus on the well-known example of sub-Plinian eruption exhibiting by Mount Somma-Vesuvius: the Greenish Pumice eruption (GP). On the basis of coupled geochemical and textural analyses we investigate the volatile behavior (H2O, CO2 and halogen (F, Cl)) to better constrain (1) the magma reservoir location and pre-eruptive state and (2) the sub-Plinian eruptive style through a detailed study of the degassing processes in relation with the dynamic of the eruptive column. Results evidence that Cl act as a geobarometer for the trachytic-phonolitic melt involved during the eruption indicating that magma reservoir was at 100 MPa (Cl buffer value: 5300 ±130 ppm) and wholly H2O-saturated (pre-eruptive H2O content between 3.8 and 5.2 wt%). The eruption dynamic is clearly explained by open-system degassing processes responsible of the eruptive column instability, correlated to textural heterogeneities of the eruptive products reflecting conduit heterogeneity (smaller diameter and higher horizontal gradient in magma ascent velocity).

  8. Variations in lava composition during the March 1981 eruption of mount etna and the implications of a compositional comparison with earlier historic eruptions

    NASA Astrophysics Data System (ADS)

    Scott, S. C.

    1983-12-01

    The March 1981 eruption of Mount Etna occurred on the northern slopes of the volcano in an area previously inactive for more than 400 a. A radial fissure system extending 7.5 km and producing 20±2×106 m3 of basic hawaiite lava, opened at 2600 m a.s.l. on 17th March and migrated downslope to 1125 m a.s.l. where activity ceased on 23rd March. Gravity evidence points to the draining of a radial storage-dyke, located between sea-level and +1 km a.s.l. Whole-rock chemistry and petrography suggests that the magma in the dyke was a hybrid supporting crystal and compositional gradients developed as a result of progressively greater mixing of residual 1979 basic hawaiite magma with fresh basic hawaiite magma during permissive filling of the dyke around September 1980. These mixing gradients caused the eruption to display a significant contrast in the concentrations of Al2O3, Sr, CaO, MgO and Fe2O3 (total) between early, high-altitude and later, low-altitude products. The fresh magma which entered the high-level system around September 1980 ascended rapidly from a deep storage region at 16-24 km depth. On a FMA plot, the composition range of the 1981 lava lies at the end of a temporal variation trend defined by the composition of successive flank eruptions back to 1971 and appears to be repeated by successive eruptions between 1923 and 1949. This suggest that the chemistry of historic lavas may, in a general way, reflect the evolution path of magma in the deep storage region despite masking of detail by high-level processes such as mixing. These temporal trends may, if real, reflect successive batches of freshly generated magma from the mantle source region entering into and subsequently differentiating within the deep storage region.

  9. Digital Elevation Models of the Pre-Eruption 2000 Crater and 2004-07 Dome-Building Eruption at Mount St. Helens, Washington, USA

    USGS Publications Warehouse

    Messerich, J.A.; Schilling, S.P.; Thompson, R.A.

    2008-01-01

    Presented in this report are 27 digital elevation model (DEM) datasets for the crater area of Mount St. Helens. These datasets include pre-eruption baseline data collected in 2000, incremental model subsets collected during the 2004-07 dome building eruption, and associated shaded-relief image datasets. Each dataset was collected photogrammetrically with digital softcopy methods employing a combination of manual collection and iterative compilation of x,y,z coordinate triplets utilizing autocorrelation techniques. DEM data points collected using autocorrelation methods were rigorously edited in stereo and manually corrected to ensure conformity with the ground surface. Data were first collected as a triangulated irregular network (TIN) then interpolated to a grid format. DEM data are based on aerotriangulated photogrammetric solutions for aerial photograph strips flown at a nominal scale of 1:12,000 using a combination of surveyed ground control and photograph-identified control points. The 2000 DEM is based on aerotriangulation of four strips totaling 31 photographs. Subsequent DEMs collected during the course of the eruption are based on aerotriangulation of single aerial photograph strips consisting of between three and seven 1:12,000-scale photographs (two to six stereo pairs). Most datasets were based on three or four stereo pairs. Photogrammetric errors associated with each dataset are presented along with ground control used in the photogrammetric aerotriangulation. The temporal increase in area of deformation in the crater as a result of dome growth, deformation, and translation of glacial ice resulted in continual adoption of new ground control points and abandonment of others during the course of the eruption. Additionally, seasonal snow cover precluded the consistent use of some ground control points.

  10. An incursion of dust in the southwestern United States from April 1980 eruptions of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Mathews, L. A.; Roquemore, G. R.; St.amand, P.; Gibson, J. P.

    1982-01-01

    An intrusion of volcanic dust occurred over the northern Mojave Desert, one month before the explosive eruption of 18 May 1980. Visibility was reduced to 15 to 30 miles during meteorological conditions that should have yielded a visibility in excess of 100 miles. This intrusion was documented by particle size distributions, scanning electron microscope analysis of Nuclepore filter samples, insolation measurements, observations by Navy and NASA aircraft, and meteorological data. No further incidents have been observed to date because of a lack of simultaneous volcanic activity with the particular wind patterns that existed in April. Therefore, under certain meteorological conditions, the desert of the southwestern United States could be significantly affected by volcanic ash from an eruption of Mount St. Helens.

  11. Comparing Simultaneous Stratospheric Aerosol and Ozone Lidar Measurements with SAGE 2 Data after the Mount Pinatubo Eruption

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Poole, L. R.; McCormick, M. P.; Veiga, R. E.; Wang, P.-H.; Rizi, V.; Masci, F.; DAltorio, A.; Visconti, G.

    1995-01-01

    Stratospheric aerosol and ozone profiles obtained simultaneously from the lidar station at the University of L'Aquila (42.35 deg N, 13.33 deg E, 683 m above sea level) during the first 6 months following the eruption of Mount Pinatubo are compared with corresponding nearby Stratospheric Aerosol and Gas Experiment (SAGE) 2 profiles. The agreement between the two data sets is found to be reasonably good. The temporal change of aerosol profiles obtained by both techniques showed the intrusion and growth of Pinatubo aerosols. In addition, ozone concentration profiles derived from an empirical time-series model based on SAGE 2 ozone data obtained before the Pinatubo eruption are compared with measured profiles. Good agreement is shown in the 1991 profiles, but ozone concentrations measured in January 1992 were reduced relative to time-series model estimates. Possible reasons for the differences between measured and model-based ozone profiles are discussed.

  12. Peak flow responses to landscape disturbances caused by the cataclysmic 1980 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Major, Jon J.; Mark, Linda E.

    2006-01-01

    Years of discharge measurements that precede and follow the cataclysmic 1980 eruption of Mount St. Helens, Washington, provide an exceptional opportunity to examine the responses of peak flows to abrupt, widespread, devastating landscape disturbance. Multiple basins surrounding Mount St. Helens (300–1300 km2 drainage areas) were variously disturbed by: (1) a debris avalanche that buried 60 km2 of valley; (2) a lateral volcanic blast and associated pyroclastic flow that destroyed 550 km2 of mature forest and blanketed the landscape with silt-capped lithic tephra; (3) debris flows that reamed riparian corridors and deposited tens to hundreds of centimeters of gravelly sand on valley floors; and (4) a Plinian tephra fall that blanketed areas proximal to the volcano with up to tens of centimeters of pumiceous silt, sand, and gravel. The spatially complex disturbances produced a variety of potentially compensating effects that interacted with and influenced hydrological responses. Changes to water transfer on hillslopes and to flow storage and routing along channels both enhanced and retarded runoff. Rapid post-eruption modifications of hillslope surface textures, adjustments of channel networks, and vegetation recovery, in conjunction with the complex nature of the eruptive impacts and strong seasonal variability in regional climate hindered a consistent or persistent shift in peak discharges. Overall, we detected a short-lived (5–10 yr) increase in the magnitudes of autumn and winter peak flows. In general, peak flows were larger, and moderate to large flows (>Q2 yr) were more substantively affected than predicted by early modeling efforts. Proportional increases in the magnitudes of both small and large flows in basins subject to severe channel disturbances, but not in basins subject solely to hillslope disturbances, suggest that eruption-induced modifications to flow efficiency along alluvial channels that have very mobile beds differentially affected flows of

  13. Total sulfur dioxide emissions and pre-eruption vapor-saturated magma at Mount St. Helens, 1980-88

    SciTech Connect

    Gerlach, T.M.; McGee, K.A.

    1994-12-15

    SO{sub 2} from explosive volcanism can cause significant climatic and atmospheric impacts, but the source of the sulfur is controversial. TOMS, COSPEC, and ash leachate data for Mount St. Helens from the time of the climactic eruption on 18 May 1980 to the final stages of non-explosive degassing in 1988 give a total SO{sub 2} emission of 2 Mt. COSPEC data show a sharp drop in emission rate that was apparently controlled by a decreasing rate of magma supply. A total SO{sub 2} emission of only 0.08 Mt is estimated from melt inclusion data and the conventional assumption that themore » main sulfur source was pre-eruption melt; commonly invoked sources of {open_quotes}excess sulfur{close_quotes} (anhydrite decomposition, basaltic magma, and degassing of non-erupted magma) are unlikely in this case. Thus melt inclusions may significantly underestimate SO{sub 2} emissions and impacts of explosive volcanism on climate and the atmosphere. Measured CO{sub 2} emissions, together with the H{sub 2}O content of melt inclusions and experimental solubility data, indicate the Mount St. Helens dacite was vapor-saturated at depth prior to ascent and suggest that a vapor phase was the main source of sulfur for the 2-Mt of SO{sub 2}. A vapor source is consistent with experimental studies on the Mount St. Helens dacite and removes the need for a much debated shallow magma body. 23 refs., 3 figs.« less

  14. Sulfur isotopic characteristics of volcanic products from the September 2014 Mount Ontake eruption, Japan

    NASA Astrophysics Data System (ADS)

    Ikehata, Kei; Maruoka, Teruyuki

    2016-07-01

    Components and sulfur isotopic compositions of pyroclastic materials from the 2014 Mt. Ontake eruption were investigated. The volcanic ash samples were found to be composed of altered volcanic fragments, alunite, anhydrite, biotite, cristobalite, gypsum, ilmenite, kaolin minerals, native sulfur, orthopyroxene, plagioclase, potassium feldspar, pyrite, pyrophyllite, quartz, rutile, and smectite, and most of these minerals were likely derived from the acidic alteration zones of Mt. Ontake. The absence of juvenile material in the eruptive products indicates that the eruption was phreatic. The sulfur isotopic compositions of the water-leached sulfate, hydrochloric acid-leached sulfate, acetone-leached native sulfur, and pyrite of the samples indicate that these sulfur species were produced by disproportionation of magmatic SO2 in the hydrothermal system at temperatures of 270-281 °C. This temperature range is consistent with that inferred from the hydrothermal mineral assemblage (e.g., pyrophyllite and rutile) in the 2014 pyroclastic materials (200-300 °C). Except for the sulfur isotopic compositions of anhydrite, which may have been altered by incorporation of sulfate minerals in a fumarolic area with lower sulfur isotopic values into the underground materials during the 1979 eruption, no significant differences in the mineral assemblages and sulfur isotopic compositions of the pyroclastic materials were identified between the products of the 2014 and 1979 Ontake phreatic eruptions, which suggests geochemical similarities in the underlying hydrothermal systems before the 2014 and 1979 eruptions.

  15. Ambient airborne solids concentrations including volcanic ash at Hanford, Washington sampling sites subsequent to the Mount St. Helens eruption

    NASA Technical Reports Server (NTRS)

    Sehmel, G. A.

    1982-01-01

    Airborne solids concentrations were measured on a near daily basis at two Hanford, Washington sites after the eruption of Mount St. Helens on May 18, 1980. These sites are about 211 km east of Mount St. Helens. Collected airborne solids included resuspended volcanic ash plus normal ambient solids. Average airborne solids concentrations were greater at the Hanford meteorological station sampling site which is 24 km northwest of the Horn Rapids dam sampling site. These increased concentrations reflect the sampling site proximity to greater ash fallout depths. Both sites are in low ash fallout areas although the Hanford meteorological station site is closer to the greater ash fallout areas. Airborne solids concentrations were decreased by rain, but airborne solids concentrations rapidly increased as surfaces dried. Airborne concentrations tended to become nearly the same at both sampling sites only for July 12 and 13.

  16. Frictional properties of the Mount St. Helens gouge: Chapter 20 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Moore, Peter L.; Iverson, Neal R.; Iverson, Richard M.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Rate-weakening friction is a requirement for stick-slip behavior that is satisfied by the Mount St. Helens gouge. Indeed, regular stick-slip oscillations were observed in two experiments performed at the highest normal stress and lowest rates of shear. The conditions under which this stick-slip motion occurred indicate that the gouge also satisfies a second criterion for stick-slip behavior of materials exhibiting rateand-state dependent friction-gouge stiffness exceeds that of the ascending magma that drives upward motion of the plug. The presence of highly compliant magma as a driving element may be crucial for generating stick-slip instabilities at the shallow earthquake focal depths observed during the eruption.

  17. Overview of the 2004 to 2006, and continuing, eruption of Mount St. Helens, Washington: Chapter 1 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

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

    2008-01-01

    Rapid onset of unrest at Mount St. Helens on September 23, 2004, initiated an uninterrupted lava-dome-building eruption that continues to the time of writing this overview (spring 2006) for a volume of papers focused on this eruption. About three weeks of intense seismic unrest and localized surface uplift, punctuated by four brief explosions, constituted a ventclearing phase, during which there was a frenzy of media attention and considerable uncertainty regarding the likely course of the eruption. The third week exhibited lessened seismicity and only minor venting of steam and ash, but rapid growth of the uplift, or welt, south of the 1980-86 lava dome proceeded as magma continued to push upward. Crystalrich dacite (~65 weight percent SiO2) lava first appeared at the surface on October 11, 2004, beginning the growth of a complex lava dome of uniform chemical composition accompanied by persistent but low levels of seismicity, rare explosions, low gas emissions, and frequent rockfalls. Petrologic studies suggest that the dome lava is chiefly of 1980s vintage, but with an admixed portion of new dacite. Alternatively, it may derive from a part of the magma chamber not tapped by 1980s eruptions. Regardless, detailed investigations of crystal chemistry, melt inclusions, and isotopes reveal a complex magmatic history. Largely episodic extrusion between 1980 and 1986 produced a relatively symmetrical lava dome composed of stubby lobes. In contrast, continuous extrusion at mean rates of about 5 m3/s in autumn 2004 to 3/s in early 2006 has produced an east-west ridge of three mounds with total volume about equal to that of the old dome. During much of late 2004 to summer 2005, a succession of spines, two recumbent and one steeply sloping and each mantled by striated gouge, grew to nearly 500 m in length in the southeastern sector of the 1980 crater and later disintegrated into two mounds. Since then, growth has been concentrated in the southwestern sector, producing a

  18. The 2002-2003 eruption of Mount Etna: First insight from bulk lavas and crystal melt inclusions

    NASA Astrophysics Data System (ADS)

    Spilliaert, N.; Allard, P.; Joron, J. L.; Metrich, N.; Treuil, M.

    2003-04-01

    Fifteen months after its July-August flank 2001 eruption, Mount Etna delivered a new flank eruption from 26 October 2002 to mid-January 2003, still ongoing at present. This eruption started suddenly on both the south and north flanks [1] but, after a few days, has continued only at new fissure vents opened between 2800 and 2700 m a.s.l. on the south flank, a few hundred meters west of the 2001 fracture system. Samples of the lava flows and products of explosive activity (lava fountains and ash-laden Strombolian jets) were repeatedly collected during the eruption, in order to investigate their bulk chemistry (major and trace elements) and dissolved volatiles in crystal melt inclusions and their relationship with the 2001 eruption [2]. The preliminary results show that: a) Bulk lavas erupted from the S vents are less evolved (lower Th, higher Ni) than those from the N vents and have a different trace element composition, implying the fast uprise of a different magma batch. The most primitive S lavas were extruded at the beginning of the eruption; b) Like the 2001 ones, the S lavas carried out large amphibole phenocrysts and sandy crustal xenoliths, evidencing their analogous mechanical interaction with the sedimentary basement. However, their lower Th/Ta ratio and still higher alkali (specially Rb and Cs) content indicate their derivation from a different melting source. These products further enhance the trend of selective alkali enrichment affecting Etna basalts for the last three decades [3]; c) Results on olivine melt inclusions in the first explosive products from S vents however suggest close similarities for major elements and dissolved volatiles in the primitive melts which fed both 2002 and 2001 eruptions. Most olivines are homogenous euhedral phenocrysts, ranging in composition from Fo82 to Fo79.5. They contain clear brownish melt inclusions which do have a similar composition (CaO/Al_2O_3 = 0.66-0.71, K_2O = 2.05 wt.%, H_2O˜3 wt.%, S/Cl = 2.0) as

  19. Lava flow hazards at Mount Etna: constraints imposed by eruptive history and numerical simulations

    PubMed Central

    Negro, Ciro Del; Cappello, Annalisa; Neri, Marco; Bilotta, Giuseppe; Hérault, Alexis; Ganci, Gaetana

    2013-01-01

    Improving lava flow hazard assessment is one of the most important and challenging fields of volcanology, and has an immediate and practical impact on society. Here, we present a methodology for the quantitative assessment of lava flow hazards based on a combination of field data, numerical simulations and probability analyses. With the extensive data available on historic eruptions of Mt. Etna, going back over 2000 years, it has been possible to construct two hazard maps, one for flank and the other for summit eruptions, allowing a quantitative analysis of the most likely future courses of lava flows. The effective use of hazard maps of Etna may help in minimizing the damage from volcanic eruptions through correct land use in densely urbanized area with a population of almost one million people. Although this study was conducted on Mt. Etna, the approach used is designed to be applicable to other volcanic areas. PMID:24336484

  20. Isotopic Insights Into the Degassing and Secondary Hydration Rates of Volcanic Glass From the 1980 Eruptions of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Seligman, A. N.; Bindeman, I. N.; Van Eaton, A. R.; Hoblitt, R. P.

    2016-12-01

    Following eruption, volcanic glass undergoes hydration in its depositional environment, which overprints the history of magmatic degassing recorded in the glass. However, the rates of secondary hydration of volcanic glass used for paleoclimate studies are poorly constrained. Here, we present our results of a natural experiment using products of the 1980 eruptions of Mount St. Helens. We measured the δD of extracted water and the δ18O of the bulk glass of samples collected during the dry summer months of 1980 and compared them with material resampled in August of 2015. Results demonstrate that only samples collected from the subsurface near gas escape pipes show elevated water concentrationss (near 2.0 wt.%) and low δD (-110 to -130 ‰) and δ18O (6.0 to 6.6 ‰) values, and that the initial process of secondary hydration is not always a simple addition of low δD waters at ambient temperature. On average, the 2015 surface samples have slightly higher water contents (0.1-0.2 wt.%) and similar δ18O (6.8 - 6.9 ‰) to those collected in 1980. Given the moderate vesicularity of the samples and the slow rate of surface temperature diffusion, we attribute these observations to hydration during cooling, with only little exchange after. We also compare our results to rapidly quenched air fall pumice from the May 18th eruption, which shows moderate δD values (-74 ‰) and water concentrations (0.3 wt.%) that are closer to those for the 1980 samples. Surprisingly, the 2015 surface samples show higher δD values (+15 ‰), which we attribute to any of four possibilities: (1) evaporation or (2) degassing of underlying deposits; (3) exchange of hydrogen with local vegetation; and/or (4) microlite crystallization that aided diffusion of water. Reconstructed δD-H2O trends for the Mount St. Helens samples collected in 1980 support previous studies proposing that exsolved volatiles were trapped within a rapidly rising magma that degassed at shallow depths. The dacitic Mount

  1. The tectonic setting of Mount Vesuvius and the correlation between its eruptions and the earthquakes of the Southern Apennines

    NASA Astrophysics Data System (ADS)

    Marzocchi, Warner; Scandone, Roberto; Mulargia, Francesco

    1993-11-01

    Mount Vesuvius is emplaced on a regional NE-SW-trending fault that accommodates the stretching of the lithosphere caused by a backward retreat of the Calabrian arc. The dynamics of the Calabrian arc controls the temporal occurrence of earthquakes in the Southern Apennines and in Sicily. By means of a detailed statistical approach, we identified a significant correlation between seismic events occurring in different subsets of this geodynamic domain: seismicity changes in the Southern Apennines follow those in the Calabrian arc after 18-21 years, while seismicity changes in Sicily follow those in the Calabrian arc after 8-10 years. The seismicity changes in these three areas appear also to have affected the eruptive activity of Vesuvius in the period 1631-1944. The major effusive-explosive eruptions of this period followed the seismicity changes in the Southern Apennines after 6-13 years and those in the Calabrian arc after 36-39 years. From a tectonic point of view, this indicates a direct link between the eruptive activity of Vesuvius and the dynamics of the Calabrian arc. The backward retreat of the arc produces strain pulses propagating to adjacent areas. From a volcanological point of view, we speculate that the arrival of an extension strain pulse in the area of Vesuvius may trigger the fast movement of magma-filled cracks that stay in unstable equilibrium in the roots of the volcano.

  2. Remote Monitoring of Post-eruption Volcano Environment Based-On Wireless Sensor Network (WSN): The Mount Sinabung Case

    NASA Astrophysics Data System (ADS)

    Soeharwinto; Sinulingga, Emerson; Siregar, Baihaqi

    2017-01-01

    An accurate information can be useful for authorities to make good policies for preventive and mitigation after volcano eruption disaster. Monitoring of environmental parameters of post-eruption volcano provides an important information for authorities. Such monitoring system can be develop using the Wireless Network Sensor technology. Many application has been developed using the Wireless Sensor Network technology, such as floods early warning system, sun radiation mapping, and watershed monitoring. This paper describes the implementation of a remote environment monitoring system of mount Sinabung post-eruption. The system monitor three environmental parameters: soil condition, water quality and air quality (outdoor). Motes equipped with proper sensors, as components of the monitoring system placed in sample locations. The measured value from the sensors periodically sends to data server using 3G/GPRS communication module. The data can be downloaded by the user for further analysis.The measurement and data analysis results generally indicate that the environmental parameters in the range of normal/standard condition. The sample locations are safe for living and suitable for cultivation, but awareness is strictly required due to the uncertainty of Sinabung status.

  3. Is the 2004-05 Eruption of Mount St. Helens Tapping New Dacite From the Deep Crust?

    NASA Astrophysics Data System (ADS)

    Pallister, J. S.; Thornber, C. R.

    2005-12-01

    The 2004-05 eruption of Mount St. Helens began with seismic activity and uplift of the crater floor in late September 2004, followed by phreatic explosions and extrusion of a lava dome starting on 11 October 2004 and continuing to this time (September, 2005). Since shortly after the first spine of lava appeared, samples have been collected using a steel box dredge (``JAWS '') suspended 60 or 110 feet below a helicopter. This method was developed to acquire samples from the hot and steep-sided dome, which, because of occasional explosions and frequent collapses, has been unsafe to approach on the ground. To date, 21 samples have been collected from the six spines of the new lava dome and petrologic studies of these samples are reported in this session. The lava dome is composed of dacite (65 wt% SiO2) that is geochemically uniform and slightly more evolved than the 1980-86 dacite. The typical lava is crystal-rich with ~50% phenocrysts of plagioclase, amphibole, hypersthene, and Fe-Ti oxides in a microcrystalline matrix that contains ~13% microlites, ~13% glass and ~25% vesicles. Oxide thermometer data for early spine samples cluster at 840-850° C and NNO+1 log unit. In contrast, samples erupted during the winter of 2004-05 have zoned oxides with apparent temperatures that range to >950° C. Such late-stage heating is likely due to latent heat evolved during rapid groundmass crystallization, or possibly to heating by new magma. Low volatile contents, presence of trydimite and quartz microlites and decreasing H2O with increasing SiO2 in the rhyolite matrix glass indicate extensive shallow (<1 km) crystallization, driven by degassing of water. Major and trace elements of the 1980-86 and 2004-2005 magma batches are similar, which led us to the initial interpretation that the dacite was magma "left over" from the 1980-1986 activity. However, new petrologic and geochemical data suggest instead that the 2004-05 eruption may be fueled by a new batch of dacite magma derived

  4. Sixty thousand years of magmatic volatile history before the caldera-forming eruption of Mount Mazama, Crater Lake, Oregon

    USGS Publications Warehouse

    Wright, Heather M.; Bacon, Charles R.; Vazquez, Jorge A.; Sisson, Thomas W.

    2012-01-01

    The well-documented eruptive history of Mount Mazama, Oregon, provides an excellent opportunity to use pre-eruptive volatile concentrations to study the growth of an explosive silicic magmatic system. Melt inclusions (MI) hosted in pyroxene and plagioclase crystals from eight dacitic–rhyodacitic eruptive deposits (71–7.7 ka) were analyzed to determine variations in volatile-element concentrations and changes in magma storage conditions leading up to and including the climactic eruption of Crater Lake caldera. Temperatures (Fe–Ti oxides) increased through the series of dacites, then decreased, and increased again through the rhyodacites (918–968 to ~950 to 845–895 °C). Oxygen fugacity began at nickel–nickel-oxide buffer (NNO) +0.8 (71 ka), dropped slightly to NNO +0.3, and then climbed to its highest value with the climactic eruption (7.7 ka) at NNO +1.1 log units. In parallel with oxidation state, maximum MI sulfur concentrations were high early in the eruptive sequence (~500 ppm), decreased (to ~200 ppm), and then increased again with the climactic eruption (~500 ppm). Maximum MI sulfur correlates with the Sr content (as a proxy for LREE, Ba, Rb, P2O5) of recharge magmas, represented by basaltic andesitic to andesitic enclaves and similar-aged lavas. These results suggest that oxidized Sr-rich recharge magmas dominated early and late in the development of the pre-climactic dacite–rhyodacite system. Dissolved H2O concentrations in MI do not, however, correlate with these changes in dominant recharge magma, instead recording vapor solubility relations in the developing shallow magma storage and conduit region. Dissolved H2O concentrations form two populations through time: the first at 3–4.6 wt% (with a few extreme values up to 6.1 wt%) and the second at ≤2.4 wt%. CO2 concentrations measured in a subset of these inclusions reach up to 240 ppm in early-erupted deposits (71 ka) and are below detection in climactic deposits (7.7 ka). Combined H2O and

  5. The Response of Ozone and Nitrogen Dioxide to the Eruption of Mount Pinatubo

    NASA Technical Reports Server (NTRS)

    Aquila. Valentina; Oman, Luke D.; Stolarsk, Richard S.; Douglass, Anne R.; Newman, Paul A.

    2012-01-01

    Observations have shown that the global mass of nitrogen dioxide decreased in both hemispheres in the year following the eruption of Mt. Pinatubo, indicating an enhanced heterogeneous chemistry. In contrast, the observed ozone response was largely asymmetrical with respect to the equator, with a decrease in the northern hemisphere and little change in the southern hemisphere. Simulations including enhanced heterogeneous chemistry due to the presence of the volcanic aerosol reproduce a decrease of ozone in the northern hemisphere, but also produce a comparable ozone decrease in the southern hemisphere, contrary to observations. Our simulations show that the heating due to the volcanic aerosol enhanced both the tropical upwelling and the extratropical downwelling. The enhanced extratropical downwelling, combined with the time of the eruption relative to the phase of the Brewer-Dobson circulation, increased the ozone in the southern hemisphere and counteracted the ozone depletion due to heterogeneous chemistry on volcanic aerosol.

  6. Isotopic insights into the degassing and secondary hydration of volcanic glass from the 1980 eruptions of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Seligman, Angela N.; Bindeman, Ilya; Van Eaton, Alexa; Hoblitt, Richard

    2018-04-01

    Abstract The magmatic degassing history of newly erupted volcanic glass is recorded in its remaining volatile content. However, this history is subsequently overprinted by post-depositional (secondary) hydration, the rates and origins of which are not yet adequately constrained. Here, we present the results of a natural experiment using products of the 1980 eruptions of Mount St. Helens. We measured water concentration, δDglass, and δ18OBSG (δ18O of the bulk silicate glass) of samples collected during the dry summer months of 1980 and compared them with material resampled in 2015 from the same deposits. Samples collected from the subsurface near gas escape pipes show elevated water concentrations (near 2.0 wt%), and these are associated with lower δDglass (- 110 to - 130‰) and δ18OBSG (6.0 to 6.6‰) values than the 1980 glass (- 70 to - 100‰ and 6.8 to 6.9‰, respectively). Samples collected in 2015 from the surface to 10-cm subsurface of the 1980 summer deposits have a small increase in average water contents of 0.1-0.2 wt% but similar δ18OBSG (6.8-6.9‰) values compared to the 1980 glass values. These samples, however, show 15‰ higher δDglass values; exchange with meteoric water is expected to yield lower δDglass values. We attribute higher δDglass values in the upper portion of the 1980 deposits collected in 2015 to rehydration by higher δD waters that were degassed for several months to a year from the hot underlying deposits, which hydrated the overlying deposits with relatively high δD gases. Our data also contribute to magmatic degassing of crystal-rich volcanoes. Using the 1980 samples, our reconstructed δD-H2O trends for the dacitic Mount St. Helens deposits with rhyolitic groundmass yield a trend that overlaps with the degassing trend for crystal-poor rhyolitic eruptions studied previously elsewhere, suggesting similar behavior of volatiles upon exsolution from magma. Furthermore, our data support previous studies proposing that

  7. Fissure eruptions at Mount Vesuvius (Italy): Insights on the shallow propagation of dikes at volcanoes

    NASA Astrophysics Data System (ADS)

    Acocella, Valerio; Porreca, Massimiliano; Neri, Marco; Mattei, Massimo; Funiciello, Renato

    2006-08-01

    Fissure eruptions may provide important information on the shallow propagation of dikes at volcanoes. Somma-Vesuvius (Italy) consists of the active Vesuvius cone, bordered to the north by the remnants of the older Somma edifice. Historical chronicles are considered to define the development of the 37 fissure eruptions between A.D. 1631 and 1944. The 1631 fissure, which reopened the magmatic conduit, migrated upward and was the only one triggered by the subvertical propagation of a dike. The other 25 fissure eruptions migrated downward, when the conduit was open, through the lateral propagation of radial dikes. We suggest two scenarios for the development of the fissures. When the summit conduit is closed, the fissures are fed by vertically propagating dikes. When the summit conduit is open, the fissures are fed by laterally propagating dikes along the volcano slopes. Consistent behaviors are found at other composite volcanoes, suggesting a general application to our model, independent of the tectonic setting and composition of magma. At Vesuvius, the historical data set and our scenarios are used to predict the consequences of the emplacement of fissures after the opening of the conduit. The results suggest that, even though the probability of opening of vents within the inhabited south and west slopes is negligible, the possibility that these are reached by a lava flow remains significant.

  8. Analysis of seismic body waves excited by the Mount St. Helens eruption of May 18, 1980

    NASA Technical Reports Server (NTRS)

    Kanamori, H.; Given, J. W.; Lay, T.

    1984-01-01

    Seismic body waves which were excited by eruption of Mt. St. Helens, and recorded by the Global Digital Seismographic Network (GDSN) stations are analyzed to determine the nature and the time sequence of the events associated with the eruption. The polarity of teleseismic P waves (period 20 sec) is identical at six stations which are distributed over a wide azimuthal range. This observation, together with a very small S to P amplitude ratio (at 20 sec), suggests that the source is a nearly vertical single force that represents the counter force of the eruption. The time history of the vertical force suggests two distinct groups of events, about two minutes apart, each consisting of several subevents with a duration of about 25 sec. The magnitude of the force is approximately 2.6 to the 17th power dyne. This vertical force is in contrast with the long period (approximately 150 sec) southward horizontal single force which was determined by a previous study and interpreted to be due to the massive landslide. Previously announced in STAR as N83-15968

  9. Analysis of seismic body waves excited by the Mount Saint Helens eruption of May 18, 1980

    NASA Astrophysics Data System (ADS)

    Kanamori, H.; Given, J. W.; Lay, T.

    Seismic body waves which were excited by eruption of Mt. St. Helens, and recorded by the Global Digital Seismographic Network (GDSN) stations are analyzed to determine the nature and the time sequence of the events associated with the eruption. The polarity of teleseismic P waves (period 20 sec) is identical at six stations which are distributed over a wide azimuthal range. This observation, together with a very small S to P amplitude ratio (at 20 sec), suggests that the source is a nearly vertical single force that represents the counter force of the eruption. The time history of the vertical force suggests two distinct groups of events, about two minutes apart, each consisting of several subevents with a duration of about 25 sec. The magnitude of the force is approximately 2.6 to the 17th power dyne. this vertical force is in contrast with the long period (approximately 150 sec) southward horizontal single force which was determined by a previous study and interpreted to be due to the massive landslide.

  10. Analysis of seismic body waves excited by the Mount Saint Helens eruption of May 18, 1980

    NASA Technical Reports Server (NTRS)

    Kanamori, H.; Given, J. W.; Lay, T.

    1982-01-01

    Seismic body waves which were excited by eruption of Mt. St. Helens, and recorded by the Global Digital Seismographic Network (GDSN) stations are analyzed to determine the nature and the time sequence of the events associated with the eruption. The polarity of teleseismic P waves (period 20 sec) is identical at six stations which are distributed over a wide azimuthal range. This observation, together with a very small S to P amplitude ratio (at 20 sec), suggests that the source is a nearly vertical single force that represents the counter force of the eruption. The time history of the vertical force suggests two distinct groups of events, about two minutes apart, each consisting of several subevents with a duration of about 25 sec. The magnitude of the force is approximately 2.6 to the 17th power dyne. this vertical force is in contrast with the long period (approximately 150 sec) southward horizontal single force which was determined by a previous study and interpreted to be due to the massive landslide.

  11. Source Mechanism Inversion of Very Long Period Strombolian Eruption Signals at Mount Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    McNamara, S. K.; Aster, R. C.; Kyle, P.

    2003-12-01

    Oscillatory, repeatable, very-long-period signals (25 s > T > 5 s) associated with strombolian eruptions of Mt. Erebus, Antarctica have been recorded by near-field broadband seismometers for several years. The eruptions are typically single, large (up to 10-m diameter), explosive bubble decompressions occurring at the surface of a phonolitic lava lake that eviscerate the lake to a depth of approximately 10 m. Associated VLP signals begin several seconds before, and continue for several minutes after, eruptions, becoming indistinguishable as lava lake recovery is achieved. We have performed waveform inversions of high signal-to-noise stacks to recover equivalent point-source moment tensor parameters and associated source time functions. Solutions are obtained by minimizing 2-norm residuals between synthetic and three-component observed seismograms using a modified version of the iterative inversion technique of Lay and Wallace (1995). We allow for varying degrees of source freedom, ranging from pure Mogi (explosive/implosive) to a complete set of six double couples and three single forces. Results suggest a shallow (<= 200 m) source region and negligible non-volumetric couple and single-force terms. During the VLP coda, the source model evolves in time towards an increasingly subhorizontal resonating crack. We will address the accuracy of using simple half-space Green's functions in such inversions and discuss source mechanism possibilities in terms of slow elastic, dynamic recharge, and other processes.

  12. Holocene Coastal Environments near Pompeii before the A.D. 79 Eruption of Mount Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Pescatore, Tullio; Senatore, Maria Rosaria; Capretto, Giovanna; Lerro, Gaia

    2001-01-01

    Studies of some 70 bore holes around ancient Pompeii, on the southwestern slope of the Somma-Vesuvius volcano, allow the reconstruction of Holocene environments earlier than the A.D. 79 eruption. This eruption produced about 10 km3 of pyroclastic material that buried the Roman cities of Pompeii, Herculaneum, and Stabiae and promoted a shoreline progradation of 1 km. The Sarno coastal plain, in a post-Miocene sedimentary basin, has been affected by Somma-Vesuvius volcanic activity since the late Pleistocene. At the Holocene transgressive maximum, the sea reached an area east of ancient Pompeii and formed a beach ridge (Messigno, 5600 and 4500 14C yr B.P.) more than 2 km inland from the present shore. Progradation of the plain due to high volcanic supply during the following highstand resulted in a new beach ridge (Bottaro-Pioppaino, 3600 14C yr B.P.) 0.5 km seaward of the Messigno ridge. Ancient Pompeii was built as the shoreline continued to prograde toward its present position. Deposits of the A.D. 79 eruption blanketed the natural levees of the Sarno River, marshes near the city and on the Sarno's floodplain, the morphological highs of Messigno and Bottaro-Pioppaino beach ridges, and the seashore. That shore was probably 1 km landward of the present one.

  13. Near-real-time information products for Mount St. Helens -- tracking the ongoing eruption: Chapter 3 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Qamar, Anthony I.; Malone, Stephen; Moran, Seth C.; Steele, William P.; Thelen, Weston A.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The rapid onset of energetic seismicity on September 23, 2004, at Mount St. Helens caused seismologists at the Pacific Northwest Seismic Network and the Cascades Volcano Observatory to quickly improve and develop techniques that summarized and displayed seismic parameters for use by scientists and the general public. Such techniques included webicorders (Web-based helicorder-like displays), graphs showing RSAM (real-time seismic amplitude measurements), RMS (root-mean-square) plots, spectrograms, location maps, automated seismic-event detectors, focal mechanism solutions, automated approximations of earthquake magnitudes, RSAM-based alarms, and time-depth plots for seismic events. Many of these visual-information products were made available publicly as Web pages generated and updated routinely. The graphs and maps included short written text that explained the concepts behind them, which increased their value to the nonseismologic community that was tracking the eruption. Laypeople could read online summaries of the scientific interpretations and, if they chose, review some of the basic data, thereby providing a better understanding of the data used by scientists to make interpretations about ongoing eruptive activity, as well as a better understanding of how scientists worked to monitor the volcano.

  14. Near- and far-field deformation associated with the ongoing dome building eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Lisowski, M.; Sherrod, D.; Lahusen, R.

    2006-12-01

    Decelerating cm-level radially inward and downward displacement of GPS stations has accompanied the ongoing eruption of Mount St. Helens. A 50-station campaign network and one continuous GPS (CGPS) network were established several years before the 23 September 2004 earthquake swarm that signaled the start of the current eruption. By mid-October 2004, Earthscope's Plate Boundary Observatory installed 10 CGPS stations and USGS Cascades Volcano Observatory added another 4 CGPS stations. The maximum inward displacement (~3 cm total since the eruption onset) occurs at stations 5 to 10 km from the vent, while maximum subsidence occurs at nearer stations. The maximum horizontal and vertical displacements are roughly equal, consistent with deformation predicted by deflation of a deep, vertically elongate magma reservoir. An elastic half-space model of a depressurizing prolate spheroidal cavity with its center 7 km deep and its top at 4 km fits the observed deformation, but the estimated cavity volume loss is only 1/3 of the ~0.07 km3 volume of the new dome. Magma resupply and/or magma compressibility can explain why observed deformation is substantially less than the amount of material erupted. Additional far-field data will become available soon, as PBO expects to complete installation of all 20 CGPS stations (4 with collocated shallow-borehole tiltmeters) and 4 deep (250 m) strain/seismic/tilt stations by October 2006. Deformation within the crater accompanying the growth of the new lava dome has been tracked with single- frequency (L1) GPS and with borehole tiltmeter stations. The velocity of GPS stations within 500 m of the vent is small (typically < 1 cm/day), while velocities of instruments placed on the growing dome itself are up to several m/day. These "whaleriders" appear to move at steady rates, at least between the 30-minute solution intervals. High rate (10 s) solutions of the GPS data will be used determine whether 1 mm to 1 cm jumps accompany the shallow

  15. Global temperature response to the major volcanic eruptions in multiple reanalysis data sets

    NASA Astrophysics Data System (ADS)

    Fujiwara, M.; Hibino, T.; Mehta, S. K.; Gray, L.; Mitchell, D.; Anstey, J.

    2015-12-01

    The global temperature responses to the eruptions of Mount Agung in 1963, El Chichón in 1982, and Mount Pinatubo in 1991 are investigated using nine currently available reanalysis data sets (JRA-55, MERRA, ERA-Interim, NCEP-CFSR, JRA-25, ERA-40, NCEP-1, NCEP-2, and 20CR). Multiple linear regression is applied to the zonal and monthly mean time series of temperature for two periods, 1979-2009 (for eight reanalysis data sets) and 1958-2001 (for four reanalysis data sets), by considering explanatory factors of seasonal harmonics, linear trends, Quasi-Biennial Oscillation, solar cycle, and El Niño Southern Oscillation. The residuals are used to define the volcanic signals for the three eruptions separately, and common and different responses among the older and newer reanalysis data sets are highlighted for each eruption. In response to the Mount Pinatubo eruption, most reanalysis data sets show strong warming signals (up to 2-3 K for 1-year average) in the tropical lower stratosphere and weak cooling signals (down to -1 K) in the subtropical upper troposphere. For the El Chichón eruption, warming signals in the tropical lower stratosphere are somewhat smaller than those for the Mount Pinatubo eruption. The response to the Mount Agung eruption is asymmetric about the equator with strong warming in the Southern Hemisphere midlatitude upper troposphere to lower stratosphere. Comparison of the results from several different reanalysis data sets confirms the atmospheric temperature response to these major eruptions qualitatively, but also shows quantitative differences even among the most recent reanalysis data sets. The consistencies and differences among different reanalysis data sets provide a measure of the confidence and uncertainty in our current understanding of the volcanic response. The results of this intercomparison study may be useful for validation of climate model responses to volcanic forcing and for assessing proposed geoengineering by stratospheric

  16. Eruptive pattern classification on Mount Etna (Sicily) and Piton de la Fournaise (La Réunion)

    NASA Astrophysics Data System (ADS)

    Falsaperla, Susanna; Langer, Horst; Ferrazzini, Valérie

    2016-04-01

    In the framework of the European MEDiterrranean Supersite Volcanoes (MED­SUV) project, Mt. Etna (Italy) and Piton de la Fournaise (La Réunion) were chosen as "European Supersite Demonstrator" and test site, respectively, to promote the transfer and implementation of efficient tools for the identification of impending volcanic activity. Both are "open-conduit volcanoes", forming ideal sites for the test and validation of innovative concepts, which can contribute to minimize volcanic hazard. One of the aims of the MED-SUV project was the development of software for machine learning applicable to data processing for early-warning purposes. Near-real time classification of continuous seismic data stream has been carried out in the control room of INGV Osservatorio Etneo since 2010. Subsequently, automatic alert procedures were activated. In the light of the excellent results for the 24/7 surveillance of Etna, we examine the portability of tools developed in the framework of the project when applied to seismic data recorded at Piton de la Fournaise. In the present application to data recorded at Piton de la Fournaise, the classifier aims at highlighting changes in the frequency content of the background seismic signal heralding the activation of the volcanic source and the imminent eruption. We describe the preliminary results of this test on a set of data of nearly two years starting on January 2014. This period follows three years of inactivity and deflation of the volcano and marks a renewal of the volcano activity with inflation, deep seismicity (-7km bsl) and five eruptions with fountains and lava flows that lasted from a few hours to more than two months. We discuss here the necessary tuning for the implementation of the software to the new dataset analyzed. We also propose a comparison with the results of pattern classification regarding recent eruptive activity at Etna.

  17. Effects of the 1980 eruption of Mount St Helens on the limnological characteristics of selected lakes in western Washington

    USGS Publications Warehouse

    Embrey, S.S.; Dion, N.P.

    1988-01-01

    The 1980 eruption of Mount St. Helens provided the opportunity to study its effect on the physical, chemical, and biological characteristics of lakes near the volcano, and to describe two newly created lakes. Concentrations of dissolved solids and organic carbon, measured in June 1980, had increased from 2 to 30 times those observed in the 1970 's in Spirit, St. Helens, and Venus Lakes. Water in the lakes was altered from preeruption calcium-bicarbonate types to calcium-sulfate, calcium sulfate-chloride, or lake surface, as in St. Helens Lake; transparency in Venus Lake had improved to a depth of 24 ft by 1982. Spirit Lake was anoxic into fall 1980, but had reaerated to 5.2 mg/L of dissolved oxygen by May 1981. Phytoplankton communities in existing lakes in the blast zone in 1980 were primarily green and bluegreen algae; diatoms were sparse until summer 1982. Small numbers of zooplankton in Spirit, St. Helens, and Venus Lakes, compared to numbers in Walupt and Fawn Lakes, may indicate some post-eruption mortality. Rotifers were absent from lakes in the blast zone, but by 1981 were observed in all the lakes. The recovery of the physical, chemical, and biological characteristics of the lakes will depend on stabilization of the surrounding environment and biological processes within each lake. Excluding Spirit Lake, it is estimated that St. Helens Lake would be the slowest to recover and Venus Lake the fastest. (USGS)

  18. Effect of temperature on the permeability of lava dome rocks from the 2004-2008 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Gaunt, H. Elizabeth; Sammonds, Peter R.; Meredith, Philip G.; Chadderton, Amy

    2016-04-01

    As magma ascends to shallow levels in the volcanic conduit, volatile exsolution can produce a dramatic increase in the crystal content of the magma. During extrusion, low porosity, highly crystalline magmas are subjected to thermal stresses which generate permeable microfracture networks. How these networks evolve and respond to changing temperature has significant implications for gas escape and hence volcano explosivity. Here, we report the first laboratory experimental study on the effect of temperature on the permeability of lava dome rocks under environmental conditions designed to simulate the shallow volcanic conduit and lava dome. Samples were collected for this study from the 2004-2008 lava dome eruption of Mount St. Helens (Washington State, USA). We show that the evolution of microfracture networks, and their permeability, depends strongly on temperature changes. Our results show that permeability decreases by nearly four orders of magnitude as temperature increases from room temperature to 800 °C. Above 800 °C, the rock samples become effectively impermeable. Repeated cycles of heating leads to sample compaction and a reduction in fracture density and therefore a decrease in permeability. We argue that changes in eruption regimes from effusive to explosive activity can be explained by strongly decreasing permeability caused by repeated heating of magma, conduit walls and volcanic plugs or domes. Conversely, magma becomes more permeable as it cools, which will reduce explosivity.

  19. Large-scale magnetic field perturbation arising from the 18 May 1980 eruption from Mount St. Helens, Washington

    USGS Publications Warehouse

    Mueller, R.J.; Johnston, M.J.S.

    1989-01-01

    A traveling magnetic field disturbance generated by the 18 may 1980 eruption of Mount St. Helens at 1532 UT was detected on an 800-km linear array of recording magnetometers installed along the San Andreas fault system in California, from San Francisco to the Salton Sea. Arrival times of the disturbance field, from the most northern of these 24 magnetometers (996 km south of the volcano) to the most southern (1493 km S23?? E), are consistent with the generation of a traveling ionospheric disturbance stimulated by the blast pressure wave in the atmosphere. The first arrivals at the north and the south ends of the array occurred at 26 and 48 min, respectively, after the initial eruption. Apparent average wave velocity through the array is 309 ?? 14 m s-1 but may have approached 600 m s-1 close to the volcano. The horizontal phase and the group velocity of ??? 300 m s-1 at periods of 70-80 min, and the attenuation with distance, strongly suggest that the magnetic field perturbations at distances of 1000-1500 km are caused by gravity mode acoustic-gravity waves propagating at F-region heights in the ionosphere. ?? 1989.

  20. Methane production and oxidation in lakes impacted by the May 18, 1980 eruption of Mount St. Helens

    SciTech Connect

    Lilley, M.D.; Baross, J.A.; Dahm, C.N.

    1988-12-01

    The concentrations of CH{sub 4} and CH{sub 4} oxidation rates were measured in lakes impacted by the May 18, 1980 eruption of Mount St. Helens. The highest CH{sub 4} concentrations were recorded during the first summer after the eruption and ranged in surface waters from 5 microM in the moderately impacted Ryan Lake to 28 microM in the heavily impacted North Coldwater Lake. At depths below the oxic/anoxic interface, CH{sub 4} levels reached 250 microM in North Coldwater Lake, 184 microM in Spirit Lake, 70 microM in Castle Creek lake, and 60 microM in Ryan Lake. The CH{sub 4} fluxmore » measurements from these lakes during the summer following the May 18, 1980 eruption were the highest ever recorded in lakes with ranges of 1.1-2.9 mmol CH{sub 4}/sq m/day in the light to moderately impacted McBride and Ryan Lakes to ranges of 17.4-25.3 mmol CH{sub 4}/sq m/day in the heavily impacted Castle Creek, North Coldwater, and Spirit Lakes. Evidence of CH{sub 4} oxidation was seen in all of the lakes during the summer of 1981, and rates of CH{sub 4} oxidation using C{sup 14}-CH{sub 4} were measured in spirit Lake from 1982 to 1986. The highest rates of CH{sub 4} oxidation measured were during the summer stratification and ranged from 50 to 150 nmol CH{sub 4} oxidized/L/day. methane oxidation rates were measured in waters having oxygen concentrations less than 100 microM with highest activity occurring at concentrations of 30-60 microM. 36 refs., 12 figs. 3 tabs.« less

  1. New Constraints on the Geochemistry of the Millennium Eruption of Mount Paektu (Changbaishan), Democratic People's Republic of Korea/China

    NASA Astrophysics Data System (ADS)

    Iacovino, K.; Kim, J. S.; Sisson, T. W.; Lowenstern, J. B.; Jang, J. N.; Song, K. H.; Ham, H. H.; Ri, K. H.; Donovan, A. R.; Oppenheimer, C.; Hammond, J. O. S.; Weber Liu, K.; Ryu, K. R.

    2015-12-01

    Mount Paektu (also known as Changbaishan) is a large caldera located on the border between China and the Democratic People's Republic of Korea. Circa 946 AD, Paektu produced one of the largest volcanic eruptions in recorded history, the so-called Millennium Eruption (ME), whose combined fall and pyroclastic flow deposits total approximately 25 km3 dense rock equivalent (95% commendite, 5% late stage trachyte). Despite its recent and potentially destructive history, the volcano is not well studied due to its relative inaccessibility. A seismic swarm beneath the volcano's summit in 2002-2005 spurred a unique collaboration between scientists from the DPRK, US, and the UK with the goals of characterizing Paektu's eruptive history and assessing its current state of activity. We present new results from this collaboration, including major and trace element (XRF, EMP and SHRIMP-RG) and volatile data (SHRIMP-RG and FTIR) on feldspar-, clinopyroxene-, and olivine-hosted melt inclusions (MI), matrix glasses, and bulk pumices from four ME comendites and one ME trachyte. MI are halogen rich (F≤4000 ppm, Cl≤5000 ppm) with moderate S (≤250 ppm) and H2O (≤4 wt%) and minimal CO2 (≤15 ppm, detection limit ~2 ppm). H2O contents in comendite MI indicate saturation pressures (at 725 °C) of ~150 MPa, corresponding to a magma chamber depth of ~6 km, similar to the depth inferred for the magmatic injection thought to have resulted in the 2002-05 earthquake swarm. ME comendite is consistent with a ca. 25% residual melt by fractional crystallization from an ME trachyte parent. Published U-series zircon ages from ME comendite indicate a magma residence time of 11ky. Thus, the late stage ME trachyte likely represents a mafic recharge event of a melt separate from but geochemically similar to the original ME comendite parent.

  2. Seismic Moment Rate Function Inversions from Very Long Period Signals Associated with Strombolian Eruptions at Mount Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Lucero, C.; Aster, R. C.; Borchers, B.; Kyle, P.

    2005-12-01

    Mount Erebus, Antarctica, shows persistent Strombolian activity, principally in the form of impulsive eruptions of simple and very large (up to 10 m diameter) gas bubbles through its long-lived phonolitic lava lake. Eruptions produce oscillatory near-field very long period (VLP; ~8-20 s period) seismic signals due to processes occurring (seconds) before, during, and (up to several minutes) following the characteristic bubble bursts that mark the onset of short period (>1 Hz) seismoacoustic signals. Coupled broadband seismoacoustic and video analysis shows that this signal is associated with three corresponding component processes: 1) the bubble ascent phase characterized by gas/lava mass transport within the conduit system that can produce a positive or negative vertical rate of momentum change, depending on the event; 2) the eruptive evisceration of the lava lake to a depth of up to 10's of m in the explosive surface decompression of the gas bubble; 3) the refilling and reestablishment gravitational equilibrium within the conduit system. We employ a new method for efficiently solving the inverse problem of finding either independent or proportional moment-tensor element rate functions using three-component near-field seismograms recorded at multiple seismic stations. The method incorporates a frequency-domain deconvolution that, in its most general formulation, solves for six independent moment rate tensor force couple time functions plus a vertical force time function. We present an efficient scheme for solving this problem using conjugate gradient methods and apply it to Erebus VLP signals from the past several years of activity.

  3. Mercury content of equisetum plants around mount st. Helens one year after the major eruption.

    PubMed

    Siegel, B Z; Siegel, S M

    1982-04-16

    The mercury content of young Equisetum plants collected around Mount St. Helens was higher in the direction of Yakima and Toppenish, Washington (northeast to east-northeast), than at any other compass heading and was about 20 times that measured around Portland, Oregon. The increase in substratum mercury was not as pronounced as that in plants but was also higher toward the northeast, the direction taken by the May 1980 volcanic plume.

  4. Filter measurements of stratospheric sulfate and chloride in the eruption plume of mount st. Helens.

    PubMed

    Gandrud, B W; Lazrus, A L

    1981-02-20

    Five flights of the U-2 aircraft with a filter sampler aboard were flown in the Mount St. Helens debris from 19 May to 17 June 1980. Sulfate concentrations as large as 216 times the expected background were observed. The enhancements of acid chloride vapor were considerably smaller, suggesting an insignificant increase of background values of hydrogen chloride once the plume is well mixed throughout the lower stratosphere.

  5. Eruptive activity at Mount St Helens, Washington, USA, 1984-1988: a gas geochemistry perspective

    USGS Publications Warehouse

    McGee, K.A.; Sutton, A.J.

    1994-01-01

    The results from two different types of gas measurement, telemetered in situ monitoring of reducing gases on the dome and airborne measurements of sulfur dioxide emission rates in the plume by correlation spectrometry, suggest that the combination of these two methods is particularly effective in detecting periods of enhanced degassing that intermittently punctuate the normal background leakage of gaseous effluent from Mount St Helens to the atmosphere. Gas events were recorded before lava extrusion for each of the four dome-building episodes at Mount St Helens since mid-1984. For two of the episodes, precursory reducing gas peaks were detected, whereas during three of the episodes, COSPEC measurements recorded precursory degassing of sulfur dioxide. During one episode (October 1986), both reducing gas monitoring and SO2 emission rate measurements simultaneously detected a large gas release several hours before lava extrusion. Had both types of gas measurements been operational during each of the dome-building episodes, it is thought that both would have recorded precursory signals for all four episodes. Evidence from the data presented herein suggests that increased degassing at Mount St Helens becomes detectable when fresh upward-moving magma is between 2 km and a few hundred meters below the base of the dome and between about 60 and 12 hours before the surface extrusion of lava. ?? 1994 Springer-Verlag.

  6. Insight into eruptive cyclic behavior of Mount Etna during 2011: geophysical and geochemical constraints

    NASA Astrophysics Data System (ADS)

    Coltelli, M.; Patanè, D.; Aiuppa, A.; Aliotta, M.; Aloisi, M.; Behncke, B.; Cannata, A.; Cannavò, F.; Di Grazia, G.; Gambino, S.; Gurrieri, S.; Mattia, M.; Montalto, P.; Prestifilippo, M.; Puglisi, G.; Salerno, G.; Scandura, D.

    2012-04-01

    The period 2009-2011 at Mt. Etna was characterized by a gradual intensification of volcanic activity. In particular, after the end of the 2008-2009 eruption a resting phase took place and lasted up to the first months of 2010. In 2010 several episodes of minor explosions, taking place at the summit craters and accompanied by mild ash emissions, testified the ongoing recharging phase started at the end of 2009 suggested by ground deformation GPS data. During 2011 volcanic activity culminated with a series of 18 lava fountains, occurring at the new South-East crater. A multiparametric approach, consisting in collecting and comparing volcanological, geophysical and geochemical data, was applied to investigate the volcano dynamics during 2009-2011. In particular, temporal and/or spatial variations of volcanic tremor, long period events, very long period events, soil deformation (GPS and tiltmeter data), SO2 flux, SO2/CO2 ratio were studied. Further, on the basis of such data FEM models were developed to follow the evolution of intrusive and eruptive processes. In conclusion, new insights into the geometry of the magma plumbing system feeding the fountaining activities, as well as into the processes of magma discharge and recharge, were obtained.

  7. Predicting and validating the motion of an ash cloud during the 2006 eruption of Mount Augustine volcano

    USGS Publications Warehouse

    Collins, Richard L.; Fochesatto, Javier; Sassen, Kenneth; Webley, Peter W.; Atkinson, David E.; Dean, Kenneson G.; Cahill, Catherine F.; Mizutani, Kohei

    2007-01-01

    On 11 January 2006, Mount Augustine volcano in southern Alaska began erupting after 20- year repose. The Anchorage Forecast Office of the National Weather Service (NWS) issued an advisory on 28 January for Kodiak City. On 31 January, Alaska Airlines cancelled all flights to and from Anchorage after multiple advisories from the NWS for Anchorage and the surrounding region. The Alaska Volcano Observatory (AVO) had reported the onset of the continuous eruption. AVO monitors the approximately 100 active volcanoes in the Northern Pacific. Ash clouds from these volcanoes can cause serious damage to an aircraft and pose a serious threat to the local communities, and to transcontinental air traffic throughout the Arctic and sub-Arctic region. Within AVO, a dispersion model has been developed to track the dispersion of volcanic ash clouds. The model, Puff, was used operational by AVO during the Augustine eruptive period. Here, we examine the dispersion of a volcanic ash (or aerosol) cloud from Mount Augustine across Alaska from 29 January through the 2 February 2006. We present the synoptic meteorology, the Puff predictions, and measurements from aerosol samplers, laser radar (or lidar) systems, and satellites. Aerosol samplers revealed the presence of volcanic aerosols at the surface at sites where Puff predicted the ash clouds movement. Remote sensing satellite data showed the development of the ash cloud in close proximity to the volcano consistent with the Puff predictions. Two lidars showed the presence of volcanic aerosol with consistent characteristics aloft over Alaska and were capable of detecting the aerosol, even in the presence of scattered clouds and where the ash cloud is too thin/disperse to be detected by remote sensing satellite data. The lidar measurements revealed the different trajectories of ash consistent with the Puff predictions. Dispersion models provide a forecast of volcanic ash cloud movement that might be undetectable by any other means but are

  8. Effects of coarse woody debris and its removal on a channel affected by the 1980 eruption of Mount St. Helens, Washington

    Treesearch

    Thomas E. Lisle

    1995-01-01

    Abstract - During the May 18, 1980, eruption of Mount St. Helens, Washington, a pyroclastic surge introduced large volumes of coarse woody debris (CWD) and fine grained sediment to Clearwater Creek, approximately 15 km northeast of the summit. Effects of controlled CWD removal on sediment storage, substrate, and pool frequency and volume were measured in four reaches,...

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-02-19

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

  11. Changes in stratospheric water vapor associated with the mount st. Helens eruption.

    PubMed

    Murcray, D G; Murcray, F J; Barker, D B; Mastenbrook, H J

    1981-02-20

    A frost point hygrometer designed for aircraft operation was included in the complement of instruments assembled for the NASA U-2 flights through the plume of Mount St. Helens. Measurements made on the 22 May flight showed the water vapor to be closely associated with the aerosol plume. The water vapor mixing ratio by mass in the plume was as high as 40 x 10(-6). This compares with values of 2 x 10(-6) to 3 x 10(-6) outside of the plume.

  12. 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.

  13. Immediate public health concerns and actions in volcanic eruptions: lessons from the Mount St. Helens eruptions, May 18-October 18, 1980.

    PubMed Central

    Bernstein, R S; Baxter, P J; Falk, H; Ing, R; Foster, L; Frost, F

    1986-01-01

    A comprehensive epidemiological evaluation of mortality and short-term morbidity associated with explosive volcanic activity was carried out by the Centers for Disease Control in collaboration with affected state and local health departments, clinicians, and private institutions. Following the May 18, 1980 eruption of Mount St. Helens, a series of public health actions were rapidly instituted to develop accurate information about volcanic hazards and to recommend methods for prevention or control of adverse effects on safety and health. These public health actions included: establishing a system of active surveillance of cause-specific emergency room (ER) visits and hospital admissions in affected and unaffected communities for comparison; assessing the causes of death and factors associated with survival or death among persons located near the crater; analyzing the mineralogy and toxicology of sedimented ash and the airborne concentration of resuspended dusts; investigating reported excesses of ash-related adverse respiratory effects by epidemiological methods such as cross-sectional and case-control studies; and controlling rumors and disseminating accurate, timely information about volcanic hazards and recommended preventive or control measures by means of press briefings and health bulletins. Surveillance and observational studies indicated that: excess in morbidity were limited to transient increases in ER visits and hospital admissions for traumatic injuries and respiratory problems (but not for communicable disease or mental health problems) which were associated in time, place, and person with exposures to volcanic ash; excessive mortality due to suffocation (76 per cent), thermal injuries (12 per cent), or trauma (12 per cent) by ash and other volcanic hazards was directly proportional to the degree of environmental damage--that is, it was more pronounced among those persons (48/65, or about 74 per cent) who, at the time of the eruption, were residing

  14. Immediate public health concerns and actions in volcanic eruptions: lessons from the Mount St. Helens eruptions, May 18-October 18, 1980.

    PubMed

    Bernstein, R S; Baxter, P J; Falk, H; Ing, R; Foster, L; Frost, F

    1986-03-01

    A comprehensive epidemiological evaluation of mortality and short-term morbidity associated with explosive volcanic activity was carried out by the Centers for Disease Control in collaboration with affected state and local health departments, clinicians, and private institutions. Following the May 18, 1980 eruption of Mount St. Helens, a series of public health actions were rapidly instituted to develop accurate information about volcanic hazards and to recommend methods for prevention or control of adverse effects on safety and health. These public health actions included: establishing a system of active surveillance of cause-specific emergency room (ER) visits and hospital admissions in affected and unaffected communities for comparison; assessing the causes of death and factors associated with survival or death among persons located near the crater; analyzing the mineralogy and toxicology of sedimented ash and the airborne concentration of resuspended dusts; investigating reported excesses of ash-related adverse respiratory effects by epidemiological methods such as cross-sectional and case-control studies; and controlling rumors and disseminating accurate, timely information about volcanic hazards and recommended preventive or control measures by means of press briefings and health bulletins. Surveillance and observational studies indicated that: excess in morbidity were limited to transient increases in ER visits and hospital admissions for traumatic injuries and respiratory problems (but not for communicable disease or mental health problems) which were associated in time, place, and person with exposures to volcanic ash; excessive mortality due to suffocation (76 per cent), thermal injuries (12 per cent), or trauma (12 per cent) by ash and other volcanic hazards was directly proportional to the degree of environmental damage--that is, it was more pronounced among those persons (48/65, or about 74 per cent) who, at the time of the eruption, were residing

  15. Initial Effects of the Mount St. Helens Eruption on Nitrogen Cycle and Related Chemical Processes in Ryan Lake

    PubMed Central

    Dahm, Clifford N.; Baross, John A.; Ward, Amelia K.; Lilley, Marvin D.; Sedell, James R.

    1983-01-01

    Ryan Lake, a 1.6-hectare basin lake near the periphery of the tree blowdown area in the blast zone 19 km north of Mount St. Helens, was studied from August to October 1980 to determine the microbial and chemical response of the lake to the eruption. Nutrient enrichment through the addition of fresh volcanic material and the organic debris from the surrounding conifer forest stimulated intense microbial activity. Concentrations of such nutrients as phosphorus, sulfur, manganese, iron, and dissolved organic carbon were markedly elevated. Nitrogen cycle activity was especially important to the lake ecosystem in regulating biogeochemical cycling owing to the limiting abundance of nitrogen compounds. Nitrogen fixation, both aerobic and anaerobic, was active from aerobic benthic and planktonic cyanobacteria with rates up to 210 nmol of N2 cm−1 h−1 and 667 nmol of N2 liter−1 h−1, respectively, and from anaerobic bacteria with rates reaching 220 nmol of N2 liter−1 h−1. Nitrification was limited to the aerobic epilimnion and littoral zones where rates were 43 and 261 nmol of NO2 liter−1 day−1, respectively. Potential denitrification rates were as high as 30 μmol of N2O liter−1 day−1 in the anaerobic hypolimnion. Total bacterial numbers ranged from 1 × 106 to 3 × 108 ml−1 with the number of viable sulfur-metal-oxidizing bacteria reaching 2 × 106 ml−1 in the hypolimnion. A general scenario for the microbial cycling of nitrogen, carbon, sulfur, and metals is presented for volcanically impacted lakes. The important role of nitrogen as these lakes recover from the cataclysmic eruption and proceed back towards their prior status as oligotrophic alpine lakes is emphasized. Images PMID:16346298

  16. Initial effects of the mount st. Helens eruption on nitrogen cycle and related chemical processes in ryan lake.

    PubMed

    Dahm, C N; Baross, J A; Ward, A K; Lilley, M D; Sedell, J R

    1983-05-01

    Ryan Lake, a 1.6-hectare basin lake near the periphery of the tree blowdown area in the blast zone 19 km north of Mount St. Helens, was studied from August to October 1980 to determine the microbial and chemical response of the lake to the eruption. Nutrient enrichment through the addition of fresh volcanic material and the organic debris from the surrounding conifer forest stimulated intense microbial activity. Concentrations of such nutrients as phosphorus, sulfur, manganese, iron, and dissolved organic carbon were markedly elevated. Nitrogen cycle activity was especially important to the lake ecosystem in regulating biogeochemical cycling owing to the limiting abundance of nitrogen compounds. Nitrogen fixation, both aerobic and anaerobic, was active from aerobic benthic and planktonic cyanobacteria with rates up to 210 nmol of N(2) cm h and 667 nmol of N(2) liter h, respectively, and from anaerobic bacteria with rates reaching 220 nmol of N(2) liter h. Nitrification was limited to the aerobic epilimnion and littoral zones where rates were 43 and 261 nmol of NO(2) liter day, respectively. Potential denitrification rates were as high as 30 mumol of N(2)O liter day in the anaerobic hypolimnion. Total bacterial numbers ranged from 1 x 10 to 3 x 10 ml with the number of viable sulfur-metal-oxidizing bacteria reaching 2 x 10 ml in the hypolimnion. A general scenario for the microbial cycling of nitrogen, carbon, sulfur, and metals is presented for volcanically impacted lakes. The important role of nitrogen as these lakes recover from the cataclysmic eruption and proceed back towards their prior status as oligotrophic alpine lakes is emphasized.

  17. Analysis of recently digitized continuous seismic data recorded during the March-May, 1980, eruption sequence at Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Moran, S. C.; Malone, S. D.

    2013-12-01

    The May 18, 1980, eruption of Mount St. Helens (MSH) was an historic event, both for society and for the field of volcanology. However, our knowledge of the eruption and the precursory period leading up it is limited by the fact that most of the data, particularly seismic recordings, were not kept due to severe limitations in the amount of digital data that could be handled and stored using 1980 computer technology. Because of these limitations, only about 900 digital event files have been available for seismic studies of the March-May seismic sequence out of a total of more than 4,000 events that were counted using paper records. Fortunately, data from a subset of stations were also recorded continuously on a series of 24 analog 14-track IRIG magnetic tapes. We have recently digitized these tapes and time-corrected and cataloged the resultant digital data streams, enabling more in-depth studies of the (almost) complete pre-eruption seismic sequence using modern digital processing techniques. Of the fifteen seismic stations operating near MSH for at least a part of the two months between March 20 and May 18, six stations have relatively complete analog recordings. These recordings have gaps of minutes to days because of radio noise, poor tape quality, or missing tapes. In addition, several other stations have partial records. All stations had short-period vertical-component sensors with very limited dynamic range and unknown response details. Nevertheless, because the stations were at a range of distances and were operated at a range of gains, a variety of earthquake sizes were recorded on scale by at least one station, and therefore a much more complete understanding of the evolution of event types, sizes and character should be achievable. In our preliminary analysis of this dataset we have found over 10,000 individual events as recorded on stations 35-40 km from MSH, spanning a recalculated coda-duration magnitude range of ~1.5 to 4.1, including many M < 3

  18. Bimodal Density Distribution of Cryptodome Dacite from the 1980 Eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Hoblitt, R.P.; Harmon, R.S.

    1993-01-01

    The explosion of a cryptodome at Mount St. Helens in 1980 produced two juvenile rock types that are derived from the same source magma. Their differences-color, texture and density-are due only to vesicularity differences. The vesicular gray dacite comprises bout 72% of the juvenile material; the black dacite comprises the other 28%. The density of juvenile dacite is bimodally distributed, with peaks at 1.6 g cm-3 (gray dacite) and 2.3 g cm-3 (black dacite). Water contents, deuterium abundances, and the relationship of petrographic structures to vapor-phase crystals indicate both rock types underwent pre-explosion subsurface vesiculation and degassing. The gray dacite underwent a second vesiculation event, probably during the 18 May explosion. In the subsurface, gases probably escaped through interconnected vesicles into the permeable volcanic edifice. We suggest that nonuniform degassing of an initially homogeneous magma produced volatile gradients in the cryptodome and that these gradients were responsible for the density bimodality. That is, water contents less than about 0.2-0.4 wt% produced vesicle growth rates that were slow in comparison to the pyroclast cooling rates; greater water contents produced vesicle growth rates that were fast in comparison to cooling rates. In this scheme, the dacite densities are bimodally distributed simply because, following decompression on 18 May 1980, one clast population vesiculated while the other did not. For clasts that did vesiculate, vesicle growth continued until it was arrested by fragmentation. ?? 1993 Springer-Verlag.

  19. Vegetation patterns 25 years after the eruption of Mount St. Helens, Washington, USA.

    PubMed

    Del Moral, Roger; Lacher, Iara L

    2005-12-01

    In 2004, we surveyed the vegetation on Mount St. Helens to document changes since 1992. We asked how communities differentiate and if they develop predictable relationships with local environments. We sought evidence from links between species and environment and changes in community structure in 271 250-m(2) plots. The habitats of the seven community types (CTs) overlapped broadly. Ordination methods demonstrated weak correlations among species distributions and location, elevation, and surface variables. Comparisons to 1992 by habitat demonstrated a large increase in plant cover and substantial development of vegetation structure. Pioneer species declined while mosses increased proportionately leading to more pronounced dominance hierarchies in most habitats. In Lupinus colonies, dominance declined, and diversity increased due to the increased abundance of formerly rare species. On once barren sites, dominance increased, but diversity changed slightly, which suggested the incipient development of competitive hierarchies. Weak correlations between vegetation and the environment suggested that initially stochastic establishment patterns had not yet been erased by deterministic factors. A vegetation mosaic that is loosely controlled by environmental factors may produce different successional trajectories that lead to alternative stable communities in similar habitats. This result has implications for restoration planning.

  20. Landscape Response to the 1980 Eruption of Mount St. Helens: Using Historical Aerial Photography to Measure Surface Change

    NASA Astrophysics Data System (ADS)

    Sweeney, K.; Major, J. J.

    2016-12-01

    Advances in structure-from-motion (SfM) photogrammetry and point cloud comparison have fueled a proliferation of studies using modern imagery to monitor geomorphic change. These techniques also have obvious applications for reconstructing historical landscapes from vertical aerial imagery, but known challenges include insufficient photo overlap, systematic "doming" induced by photo-spacing regularity, missing metadata, and lack of ground control. Aerial imagery of landscape change in the North Fork Toutle River (NFTR) following the 1980 eruption of Mount St. Helens is a prime dataset to refine methodologies. In particular, (1) 14-μm film scans are available for 1:9600 images at 4-month intervals from 1980 - 1986, (2) the large magnitude of landscape change swamps systematic error and noise, and (3) stable areas (primary deposit features, roads, etc.) provide targets for both ground control and matching to modern lidar. Using AgiSoft PhotoScan, we create digital surface models from the NFTR imagery and examine how common steps in SfM workflows affect results. Tests of scan quality show high-resolution, professional film scans are superior to office scans of paper prints, reducing spurious points related to scan infidelity and image damage. We confirm earlier findings that cropping and rotating images improves point matching and the final surface model produced by the SfM algorithm. We demonstrate how the iterative closest point algorithm, implemented in CloudCompare and using modern lidar as a reference dataset, can serve as an adequate substitute for absolute ground control. Elevation difference maps derived from our surface models of Mount St. Helens show patterns consistent with field observations, including channel avulsion and migration, though systematic errors remain. We suggest that subtracting an empirical function fit to the long-wavelength topographic signal may be one avenue for correcting systematic error in similar datasets.

  1. A retrospective study on acute health effects due to volcanic ash exposure during the eruption of Mount Etna (Sicily) in 2002

    PubMed Central

    2013-01-01

    Background Mount Etna, located in the eastern part of Sicily (Italy), is the highest and most active volcano in Europe. During the sustained eruption that occurred in October-November 2002 huge amounts of volcanic ash fell on a densely populated area south-east of Mount Etna in Catania province. The volcanic ash fall caused extensive damage to infrastructure utilities and distress in the exposed population. This retrospective study evaluates whether or not there was an association between ash fall and acute health effects in exposed local communities. Methods We collected the number and type of visits to the emergency department (ED) for diseases that could be related to volcanic ash exposure in public hospitals of the Province of Catania between October 20 and November 7, 2002. We compared the magnitude of differences in ED visits between the ash exposure period in 2002 and the same period of the previous year 2001. Results We observed a significant increase of ED visits for acute respiratory and cardiovascular diseases, and ocular disturbances during the ash exposure time period. Conclusions There was a positive association between exposure to volcanic ash from the 2002 eruption of Mount Etna and acute health effects in the Catania residents. This study documents the need for public health preparedness and response initiatives to protect nearby populations from exposure to ash fall from future eruptions of Mount Etna. PMID:23924394

  2. Seismic-monitoring changes and the remote deployment of seismic stations (seismic spider) at Mount St. Helens, 2004-2005: Chapter 7 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    McChesney, Patrick J.; Couchman, Marvin R.; Moran, Seth C.; Lockhart, Andrew B.; Swinford, Kelly J.; LaHusen, Richard G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The instruments in place at the start of volcanic unrest at Mount St. Helens in 2004 were inadequate to record the large earthquakes and monitor the explosions that occurred as the eruption developed. To remedy this, new instruments were deployed and the short-period seismic network was modified. A new method of establishing near-field seismic monitoring was developed, using remote deployment by helicopter. The remotely deployed seismic sensor was a piezoelectric accelerometer mounted on a surface-coupled platform. Remote deployment enabled placement of stations within 250 m of the active vent.

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

    NASA Astrophysics Data System (ADS)

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

    2018-04-01

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

  4. Rapid, low-cost photogrammetry to monitor volcanic eruptions: an example from Mount St. Helens, Washington, USA

    USGS Publications Warehouse

    Diefenbach, Angela K.; Crider, Juliet G.; Schilling, Steve P.; Dzurisin, Daniel

    2012-01-01

    We describe a low-cost application of digital photogrammetry using commercially available photogrammetric software and oblique photographs taken with an off-the-shelf digital camera to create sequential digital elevation models (DEMs) of a lava dome that grew during the 2004–2008 eruption of Mount St. Helens (MSH) volcano. Renewed activity at MSH provided an opportunity to devise and test this method, because it could be validated against other observations of this well-monitored volcano. The datasets consist of oblique aerial photographs (snapshots) taken from a helicopter using a digital single-lens reflex camera. Twelve sets of overlapping digital images of the dome taken during 2004–2007 were used to produce DEMs and to calculate lava dome volumes and extrusion rates. Analyses of the digital images were carried out using photogrammetric software to produce three-dimensional coordinates of points identified in multiple photos. The evolving morphology of the dome was modeled by comparing successive DEMs. Results were validated by comparison to volume measurements derived from traditional vertical photogrammetric surveys by the US Geological Survey Cascades Volcano Observatory. Our technique was significantly less expensive and required less time than traditional vertical photogrammetric techniques; yet, it consistently yielded volume estimates within 5% of the traditional method. This technique provides an inexpensive, rapid assessment tool for tracking lava dome growth or other topographic changes at restless volcanoes.

  5. Paleomagnetic constraints on the timing and duration of latest Pleistocene to early Holocene eruptions at Mount Shasta volcano, California, USA

    NASA Astrophysics Data System (ADS)

    Gardner, C. A.; Champion, D. E.; Christiansen, R. L.; Calvert, A. T.; Mosbrucker, A. R.

    2013-12-01

    Mount Shasta in northern California, USA, has among the highest late Pleistocene to early Holocene eruptive rates in the Cascades arc (Hildreth, 2007, USGS Prof Paper 1744). Paleomagnetic data from over 50 sites help constrain the timing and durations of these events. In late glacial times, lithic pyroclastic flows of unknown volume and age swept down all flanks of the volcano, followed, after a period of quiescence, by Shasta's largest known explosive event-- the pumiceous Red Banks tephra fall and pyroclastic flows at ~11 ka. The Red Banks tephra fall was closely followed by growth of the Shastina and Black Butte edifices on the west side of the volcano with the volume of the Shastina deposits alone estimated to be about 30 km3. Since cessation of activity at Shastina and Black Butte, a series of lava domes and flows built the summit Hotlum cone and inundated the N and E flanks of the volcano. Paleomagnetic secular-variation data show that the events described above have well-grouped and distinct remanence directions suggesting that individual pulses of activity occurred within short time intervals (days to decades), with periods of quiescence between them lasting longer than the eruptive activity. The total interval of time suggested by the movement of the magnetic field from pre-Red Banks through Hotlum activity is likely within 5-10 kyr. The pre-Redbanks pyroclastic flows exposed on at least three flanks of the volcano have essentially the same paleomagnetic direction of ~ D=350°, I=60° with a site mean α95of 1.8° (7/7 sites). The Red Banks eruptive products have a more easterly and shallower (~ D=2°, I=53°) remanent direction. The prominent Shastina cone on the NW flank of the volcano produced lava flows to the NW and SW of the cone and an apron of pyroclastic material to the west. Shastina pyroclastic flows and lava flows have a similar direction of ~ D=8°, I=56 (α95 from 15 sites is 1.4°) suggesting that the Shastina eruptive period lasted a

  6. Investigating Climate Responses to Large Volcanic Eruptions in an Ensemble of Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Varuolo-Clarke, A. M.; Medeiros, B.

    2014-12-01

    This research investigated the climate response to large volcanic eruptions in the Community Earth System Model (CESM). To differentiate the climatic response to volcanic eruptions from the model's natural variability, we use the CESM Large Ensemble (CESM-LE), a 30-member ensemble of 20th Century simulations of the coupled climate model. We analyzed the climate following three large 20th Century eruptions: Mount Agung, El Chichón, and Mount Pinatubo. Each volcanic eruption is simulated by an idealized aerosol distribution so each eruption's forcing is identical across ensemble members. The three climate variables we focused on were: surface temperature, precipitation, and surface pressure. With these variables we investigated global and regional climate responses. Globally, the model exhibits the expected cooling that persists for several years following large eruptions. Associated with this, the model shows that the global hydrologic cycle slows and the cooler troposphere holds less water vapor resulting in a decreased surface pressure. On the regional scale, we investigate two responses to large volcanic eruptions that have been described observationally: Northern Hemisphere winter warming, and an enhanced likelihood for El Niño Southern Oscillation (ENSO) events. Investigating the northern hemisphere winters following the eruptions, some simulations produce anomalous warming over land that is similar to the observed warming, but just as many produce anomalous cooling. Comparing the distribution of temperature anomalies, we cannot distinguish the northern hemisphere winter response from the model's natural variability. A similar analysis for ENSO events, however, hints that warm events (i.e., El Niño) are more likely following large volcanic eruptions than is typical of the model's natural variability.

  7. Subevents of long-period seismicity: implications for hydrothermal dynamics during the 2004-2008 eruption of Mount St. Helens

    USGS Publications Warehouse

    Matoza, Robin S.; Chouet, Bernard A.

    2010-01-01

    One of the most striking aspects of seismicity during the 2004–2008 eruption of Mount St. Helens (MSH) was the precise regularity in occurrence of repetitive long-period (LP) or “drumbeat” events over sustained time periods. However, this precise regularity was not always observed, and at times the temporal occurrence of LP events became more random. In addition, accompanying the dominant LP class of events during the 2004–2008 MSH eruption, there was a near-continuous, randomly occurring series of smaller seismic events. These subevents are not always simply small-amplitude versions of the dominant LP class of events but appear instead to result from a separate random process only loosely coupled to the main LP source mechanism. We present an analysis of the interevent time and amplitude distributions of the subevents, using waveform cross correlation to separate LP events from the subevents. We also discuss seismic tremor that accompanied the 8 March 2005 phreatic explosion event at MSH. This tremor consists of a rapid succession of LPs and subevents triggered during the explosion, in addition to broadband noise from the sustained degassing. Immediately afterward, seismicity returned to the pre-explosion occurrence pattern. This triggering in relation to the rapid ejection of steam from the system, and subsequent return to pre-explosion seismicity, suggests that both seismic event types originated in a region of the subsurface hydrothermal system that was (1) in contact with the reservoir feeding the 8 March 2005 phreatic explosion but (2) not destroyed or drained by the explosion event. Finally, we discuss possible thermodynamic conditions in a pressurized hydrothermal crack that could give rise to seismicity. Pressure drop estimates for typical LP events are not generally large enough to perturb pure water in a shallow hydrothermal crack into an unstable state. However, dissolved volatiles such as CO2 may lead to a more unstable system, increasing the

  8. Subevents of long-period seismicity: Implications for hydrothermal dynamics during the 2004-2008 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Chouet, Bernard A.

    2010-12-01

    One of the most striking aspects of seismicity during the 2004-2008 eruption of Mount St. Helens (MSH) was the precise regularity in occurrence of repetitive long-period (LP) or "drumbeat" events over sustained time periods. However, this precise regularity was not always observed, and at times the temporal occurrence of LP events became more random. In addition, accompanying the dominant LP class of events during the 2004-2008 MSH eruption, there was a near-continuous, randomly occurring series of smaller seismic events. These subevents are not always simply small-amplitude versions of the dominant LP class of events but appear instead to result from a separate random process only loosely coupled to the main LP source mechanism. We present an analysis of the interevent time and amplitude distributions of the subevents, using waveform cross correlation to separate LP events from the subevents. We also discuss seismic tremor that accompanied the 8 March 2005 phreatic explosion event at MSH. This tremor consists of a rapid succession of LPs and subevents triggered during the explosion, in addition to broadband noise from the sustained degassing. Immediately afterward, seismicity returned to the pre-explosion occurrence pattern. This triggering in relation to the rapid ejection of steam from the system, and subsequent return to pre-explosion seismicity, suggests that both seismic event types originated in a region of the subsurface hydrothermal system that was (1) in contact with the reservoir feeding the 8 March 2005 phreatic explosion but (2) not destroyed or drained by the explosion event. Finally, we discuss possible thermodynamic conditions in a pressurized hydrothermal crack that could give rise to seismicity. Pressure drop estimates for typical LP events are not generally large enough to perturb pure water in a shallow hydrothermal crack into an unstable state. However, dissolved volatiles such as CO2 may lead to a more unstable system, increasing the

  9. The drag forces exerted by lahar flows on a cylindrical pier: case study of post Mount Merapi eruptions

    NASA Astrophysics Data System (ADS)

    Faizien Haza, Zainul

    2018-03-01

    Debris flows of lahar flows occurred in post mount eruption is a phenomenon in which large quantities of water, mud, and gravel flow down a stream at a high velocity. It is a second stage of danger after the first danger of lava flows, pyroclastic, and toxic gases. The debris flow of lahar flows has a high density and also high velocity; therefore it has potential detrimental consequences against homes, bridges, and infrastructures, as well as loss of life along its pathway. The collision event between lahar flows and pier of a bridge is observed. The condition is numerically simulated using commercial software of computational fluid dynamic (CFD). The work is also conducted in order to investigate drag force generated during collision. Rheological data of lahar is observed through laboratory test of lahar model as density and viscosity. These data were used as the input data of the CFD simulation. The numerical model is involving two types of fluid: mud and water, therefore multiphase model is adopted in the current CFD simulation. The problem formulation is referring to the constitutive equations of mass and momentum conservation for incompressible and viscous fluid, which in perspective of two dimension (2D). The simulation models describe the situation of the collision event between lahar flows and pier of a bridge. It provides sequential view images of lahar flow impaction and the propagation trend line of the drag force coefficient values. Lahar flow analysis used non-dimensional parameter of Reynolds number. According to the results of numerical simulations, the drag force coefficients are in range 1.23 to 1.48 those are generated by value of flow velocity in range 11.11 m/s to 16.67 m/s.

  10. Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems

    USGS Publications Warehouse

    Waite, G.P.; Chouet, B.A.; Dawson, P.B.

    2008-01-01

    The current eruption at Mount St. Helens is characterized by dome building and shallow, repetitive, long-period (LP) earthquakes. Waveform cross-correlation reveals remarkable similarity for a majority of the earthquakes over periods of several weeks. Stacked spectra of these events display multiple peaks between 0.5 and 2 Hz that are common to most stations. Lower-amplitude very-long-period (VLP) events commonly accompany the LP events. We model the source mechanisms of LP and VLP events in the 0.5-4 s and 8-40 s bands, respectively, using data recorded in July 2005 with a 19-station temporary broadband network. The source mechanism of the LP events includes: 1) a volumetric component modeled as resonance of a gently NNW-dipping, steam-filled crack located directly beneath the actively extruding part of the new dome and within 100 m of the crater floor and 2) a vertical single force attributed to movement of the overlying dome. The VLP source, which also includes volumetric and single-force components, is 250 m deeper and NNW of the LP source, at the SW edge of the 1980s lava dome. The volumetric component points to the compression and expansion of a shallow, magma-filled sill, which is subparallel to the hydrothermal crack imaged at the LP source, coupled with a smaller component of expansion and compression of a dike. The single-force components are due to mass advection in the magma conduit. The location, geometry and timing of the sources suggest the VLP and LP events are caused by perturbations of a common crack system.

  11. Ground-coupled acoustic airwaves from Mount St. Helens provide constraints on the May 18, 1980 eruption

    USGS Publications Warehouse

    Johnson, J.B.; Malone, S.D.

    2007-01-01

    The May 18, 1980 Mount St. Helens eruption perturbed the atmosphere and generated atmosphere-to-ground coupled airwaves, which were recorded on at least 35 seismometers operated by the Pacific Northwest Seismograph Network (PNSN). From 102 distinct travel time picks we identify coherent airwaves crossing Washington State primarily to the north and east of the volcano. The travel time curves provide evidence for both stratospheric refractions (at 200 to 300 km from the volcano) as well as probable thermospheric refractions (at 100 to 350 km). The very few first-hand reports of audible volcano sounds within about 80 km of the volcano coincide with a general absence of ground-coupled acoustic arrivals registered within about 100 km and are attributed to upward refraction of sound waves. From the coherent refracted airwave arrivals, we identify at least four distinct sources which we infer to originate 10 s, 114 s, ∼ 180 s and 319 s after the onset of an 8:32:11 PDT landslide. The first of these sources is attributed to resultant depressurization and explosion of the cryptodome. Most of the subsequent arrivals also appear to be coincident with a source located at or near the presumed volcanic conduit, but at least one of the later arrivals suggests an epicenter displaced about 9 km to the northwest of the vent. This dislocation is compatible with the direction of the sector collapse and lateral blast. We speculate that this concussion corresponds to a northern explosion event associated with hot cryptodome entering the Toutle River Valley.

  12. Ground-coupled acoustic airwaves from Mount St. Helens provide constraints on the May 18, 1980 eruption

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Malone, Stephen D.

    2007-06-01

    The May 18, 1980 Mount St. Helens eruption perturbed the atmosphere and generated atmosphere-to-ground coupled airwaves, which were recorded on at least 35 seismometers operated by the Pacific Northwest Seismograph Network (PNSN). From 102 distinct travel time picks we identify coherent airwaves crossing Washington State primarily to the north and east of the volcano. The travel time curves provide evidence for both stratospheric refractions (at 200 to 300 km from the volcano) as well as probable thermospheric refractions (at 100 to 350 km). The very few first-hand reports of audible volcano sounds within about 80 km of the volcano coincide with a general absence of ground-coupled acoustic arrivals registered within about 100 km and are attributed to upward refraction of sound waves. From the coherent refracted airwave arrivals, we identify at least four distinct sources which we infer to originate 10 s, 114 s, ˜ 180 s and 319 s after the onset of an 8:32:11 PDT landslide. The first of these sources is attributed to resultant depressurization and explosion of the cryptodome. Most of the subsequent arrivals also appear to be coincident with a source located at or near the presumed volcanic conduit, but at least one of the later arrivals suggests an epicenter displaced about 9 km to the northwest of the vent. This dislocation is compatible with the direction of the sector collapse and lateral blast. We speculate that this concussion corresponds to a northern explosion event associated with hot cryptodome entering the Toutle River Valley.

  13. Analysis of GPS-measured deformation associated with the 2004-2006 dome-building eruption of Mount St. Helens, Washington: Chapter 15 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Lisowski, Michael; Dzurisin, Daniel; Denlinger, Roger P.; Iwatsubo, Eugene Y.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    . The discrepancy between the estimated cavity-volume loss and the >83×106-m3 volume of the erupted dome can be explained, for the most part, by exsolution of gas in the stored magma and by minor input of new magma during the eruption.

  14. Temporal and spatial variation of local stress fields before and after the 1992 eruptions of Crater Peak vent, Mount Spurr volcano, Alaska

    USGS Publications Warehouse

    Roman, D.C.; Moran, S.C.; Power, J.A.; Cashman, K.V.

    2004-01-01

    We searched for changes in local stress-field orientation at Mount Spurr volcano, Alaska, between August 1991 and December 2001. This study focuses on the stress-field orientation beneath Crater Peak vent, the site of three eruptions in 1992, and beneath the summit of Mount Spurr. Local stress tensors were calculated by inverting subsets of 140 fault-plane solutions for earthquakes beneath Crater Peak and 96 fault-plane solutions for earthquakes beneath Mount Spurr. We also calculated an upper-crustal regional stress tensor by inverting fault-plane solutions for 66 intraplate earthquakes located near Mount Spurr during 1991-2001. Prior to the 1992 eruptions, and for 11 months beginning with a posteruption seismic swarm, the axis of maximum compressive stress beneath Crater Peak was subhorizontal and oriented N67-76??E, approximately perpendicular to the regional axis of maximum compressive stress (N43??W). The strong temporal correlation between this horizontal stress-field rotation (change in position of the ??1/ ??3 axes relative to regional stress) and magmatic activity indicates that the rotation was related to magmatic activity, and we suggest that the Crater Peak stress-field rotation resulted from pressurization of a network of dikes. During the entire study period, the stress field beneath the summit of Mount Spurr also differed from the regional stress tensor and was characterized by a vertical axis of maximum compressive stress. We suggest that slip beneath Mount Spurr's summit occurs primarily on a major normal fault in response to a combination of gravitational loading, hydrothermal circulation, and magmatic processes beneath Crater Peak. Online material: Regional and local fault-plane solutions.

  15. 238U-230Th-226Ra disequilibria in dacite and plagioclase from the 2004-2005 eruption of Mount St. Helens: Chapter 36 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Cooper, Kari M.; Donnelly, Carrie T.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    230Th)/(232Th) measured for the 1980s reference suite. However, (230Th)/(232Th) for plagioclase separates for dome samples erupted during October and November 2004 are significantly different from corresponding whole-rock values, which suggests that a large fraction (>30 percent) of crystals in each sample are foreign to the host liquid. Furthermore, plagioclase in the two 2004 samples have U-series characteristics distinct from each other and from plagioclase in dacite erupted in 1982, indicating that (1) the current eruption must include a component of crystals (and potentially associated magma) that were not sampled by the 1980-86 eruption, and (2) dacite magmas erupted only a month apart in 2004 contain different populations of crystals, indicating that this foreign component is highly heterogeneous within the 2004-5 magma reservoir.

  16. Use of thermal infrared imaging for monitoring renewed dome growth at Mount St. Helens, 2004: Chapter 17 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Schneider, David J.; Vallance, James W.; Wessels, Rick L.; Logan, Matthew; Ramsey, Michael S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    A helicopter-mounted thermal imaging radiometer documented the explosive vent-clearing and effusive phases of the eruption of Mount St. Helens in 2004. A gyrostabilized gimbal controlled by a crew member housed the radiometer and an optical video camera attached to the nose of the helicopter. Since October 1, 2004, the system has provided thermal and video observations of dome growth. Flights conducted as frequently as twice daily during the initial month of the eruption monitored rapid changes in the crater and 1980-86 lava dome. Thermal monitoring decreased to several times per week once dome extrusion began. The thermal imaging system provided unique observations, including timely recognition that the early explosive phase was phreatic, location of structures controlling thermal emissions and active faults, detection of increased heat flow prior to the extrusion of lava, and recognition of new lava extrusion. The first spines, 1 and 2, were hotter when they emerged (maximum temperature 700-730°C) than subsequent spines insulated by as much as several meters of fault gouge. Temperature of gouge-covered spines was about 200°C where they emerged from the vent, and it decreased rapidly with distance from the vent. The hottest parts of these spines were as high as 500-730°C in fractured and broken-up regions. Such temperature variation needs to be accounted for in the retrieval of eruption parameters using satellite-based techniques, as such features are smaller than pixels in satellite images.

  17. From dome to dust: shallow crystallization and fragmentation of conduit magma during the 2004-2006 dome extrusion of Mount St. Helens, Washington: Chapter 19 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Cashman, Katharine V.; Thornber, Carl R.; Pallister, John S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Comparison of eruptive conditions during the 2004-6 activity at Mount St. Helens with those of other spine-forming eruptions suggests that magma ascent rates of about 10-4 m/s or less allow sufficient degassing and crystallization within the conduit to form large volcanic spines of intermediate composition (andesite to dacite). Solidification deep within the conduit, in turn, requires transport of the solid plug over long distances (hundreds of meters); resultant large strains are responsible for extensive brittle breakage and development of thick gouge zones. Moreover, similarities between gouge textures and those of ash emitted by explosions from spine margins indicate that fault gouge is the origin for the ash. As the comminution and generation of ash-sized particles was clearly a multistep process, this observation suggests that fragmentation preceded, rather than accompanied, these explosions.

  18. Time Series Surface Deformation using Multi-Temporal InSAR Technique at Mount Sinabung Eruption in North Sumatra, Indonesia

    NASA Astrophysics Data System (ADS)

    Hwang, Eui-Hong; Lee, ChangWook; Jo, Eunyoung; Lee, SeulKi; Kim, KiYeon

    2014-05-01

    Sinabung volcano in Indonesia is a part of the Pacific Ring of Fire, formed due to the subduction between the Eurasian and the Indo-Australian plate. After about 400-year dormancy, Sinabung volcano erupted on August 29, 2010 and January 4, 2014, recently. We study the surface deformation of Sinabung volcano using ALOS/PALSAR and RADARSAT-2 interferometric synthetic aperture radar (InSAR) images acquired from February 2007 to September 2013. Based on multi-temporal InSAR processing, we can generate the ground surface deformation map due to the 2010 eruption. During the 3 years before the 2010 eruption, the volcano inflated at an average rate ~1.7 cm/yr with marked higher rate of 6.6 cm/year during the 6 months prior to the 2010 eruption. The inflation is constrained to the top of the volcano. Since the 2010 eruption to January 2011, the volcano has subsided for about 3 cm (or about 6 cm/yr). The observed inflation and deflation are modeled with a Mogi and Prolate spheroid source. The source of inflation is located about 0.3 - 1.3 km below sea level directly underneath the crater. On the other hand, deflation source is modeled about 0.6-1.0 km with coeruption period. The average volumetric change was about from 1.9x10-6 to -2.7x10-5 km3/yr during the eruption event using ALOS/PALSAR images. Recently, RADARSAT-2 SAR data were applied to new eruption event from September 2013 to January 2014 for frequently eruption during short time period. We interpret the inflation was due to magma accumulation at a shallow reservoir beneath the Sinabung volcano. The deflation was due to the magma withdrawal from the shallow reservoir during the eruption as well as thermo-elastic compaction of erupted material.

  19. The 1928 eruption of Mount Etna (Italy): Reconstructing lava flow evolution and the destruction and recovery of the town of Mascali

    NASA Astrophysics Data System (ADS)

    Branca, Stefano; De Beni, Emanuela; Chester, David; Duncan, Angus; Lotteri, Alessandra

    2017-04-01

    Mount Etna in Sicily (Italy) shows > 2500 years of interactions between volcanic eruptions and human activity, and these are well documented in historical sources. During the last 400 years, flank eruptions have had major impacts on the urban fabric of the Etna region, especially in 1651-54, 1669, 1923 and 1928, and it is the last of these which is the focus of this paper. A detailed field and historical reconstruction of the 1928 eruption is presented which allows three themes to be discussed: the evolution of the flow field, lava volume and average magma discharge rate trend; the eruption's human impact, particularly the destruction of the town of Mascali; and the recovery of the region with re-construction of Mascali in a new location. Detailed mapping of lava flows allowed the following dimensions to be calculated: total area, 4.38 × 106 m2; maximum length, 9.4 km; volume, 52.91 ± 5.21 × 106 m3 and an average effusion rate of 38.5 m3 s-1. Time-averaged discharged rates are calculated allowing the reconstruction of their temporal variations during the course of the eruption evidencing a high maximum effusion rate of 374 m3 s- 1. These trends, in particular with regard to the Lower Fissure main phase of the eruption, are in accordance with the 'idealized discharge model' of Wadge (1981), proposed for basaltic eruptions driven by de-pressurization of magma sources, mainly through reservoir relaxation (i.e. elastic contraction of a magma body). The eruption took place when Italy was governed by Mussolini and the fascist party. The State response both, during and in the immediate aftermath of the eruption and in the years that followed during which Mascali was reconstructed, was impressive. This masked a less benign legacy, however, that can be traced for several subsequent decades of using responses to natural catastrophes to manufacture State prestige by reacting to, rather than planning for, disasters.

  20. Reanalysis of the Pyroclastic Fall Deposit from the 18 May 1980 Eruption of Mount Saint Helens, USA

    NASA Astrophysics Data System (ADS)

    Durant, A. J.; Rose, W. I.; Horwell, C. J.; Sarna-Wojcicki, A. M.; Wan, E.; Dartevelle, S.; Volentik, A. C.

    2006-12-01

    A new analysis of the distal fall deposit from the 18 May 1980 Eruption of Mount Saint Helens (MSH80) is presented. The removal of fine distal volcanic ash from the atmosphere is complex: From the data presented here, it is clear that meteorological processes and atmospheric dynamics influence particle settling. Original samples were analysed by a Malvern Instruments Mastersizer 2000 to determine particle size through the range 0.1-2000 μm. MSH80 fallout consists of material from an initial directed blast and ~9 hour Plinian phase, which was later dominated by coignimbrite input. A striking feature of the distal ashfall deposit is a secondary maximum in mass deposited located ~300 km from the volcano, previously attributed to ash aggregation and enhanced particle settling. Median particle size averaged by transect decreases with distance from 2.91 Φ at ~150 km to 5.35 Φ at ~300 km, then increases again before decreasing to a minimum of 5.22 Φ at ~650 km. Investigation of size fractions averaged by transect show 0-3 Φ proportions decrease with distance and >4 Φ proportions increase with distance. Contribution of 5-7 Φ size fractions peak at the secondary maximum, which may suggest that ash aggregation selectively binds particles of this size. Proportions of particles >9 Φ (<1.95 μm diameter ~ PM2.5; the most pertinent phi size fraction for health hazard assessment) remain fairly constant over the deposit at ~4-5 wt%. Samples beyond ~300 km had remarkably similar grainsize characteristics. All samples are poorly sorted with transect average σ values ranging from 2.30-1.64 Φ; samples in the secondary maximum region have the highest measured sorting coefficients. By transect average, all samples are positively skewed (0.5-0.79 Φ) and strongly leptokurtic (2.75-3.21 Φ). Some bimodal samples are present at distances less than ~300 km. Enhancement of coarse fractions between 0-3 Φ was observed to the south of these transects and may represent the footprint

  1. Evolving magma storage conditions beneath Mount St. Helens inferred from chemical variations in melt inclusions from the 1980-1986 and current (2004-2006) eruptions: Chapter 33 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Blundy, Jon; Cashman, Katharine V.; Berlo, Kim; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    O contents, consistent with magma extraction from shallow depths. Highly enriched Li in melt inclusions suggests that vapor transport of Li is a characteristic feature of Mount St. Helens. Melt inclusions from the current eruption have subtly different trace-element chemistry from all but one of the 1980-86 melt inclusions, with steeper rareearth-element (REE) patterns and low U, Th, and high-fieldstrength elements (HFSE), indicating addition of a new melt component to the magma system. It is anticipated that increasing involvement of the new melt component will be evident as the current eruption proceeds.

  2. Chlorine as a geobarometer tool: Application to the explosive eruptions of the Volcanic Campanian District (Mount Somma-Vesuvius, Phlegrean Fields, Ischia)

    NASA Astrophysics Data System (ADS)

    Balcone-Boissard, Hélène; Boudon, Georges; Zdanowicz, Géraldine; Orsi, Giovanni; Civetta, Lucia; Webster, Jim D.; Cioni, Raffaello; D'Antonio, Massimo

    2016-04-01

    volcanoes of the Neapolitan area: Mount Somma-Vesuvius, Phlegrean Fields and Ischia. We have analysed the products of the representative explosive eruptions of each volcano, including Plinian, sub-Plinian and strombolian events. We have focussed our research on the earliest emitted, most evolved products of each eruption, likely representing the shallower, fluid-saturated portion of the reservoir. As the studied eruptions cover the entire eruptive history of each volcanic system, the results allow better constraining the evolution through time of the shallow plumbing system. We highlighted for Mount Somma - Vesuvius two magma ponding zones, at ~170-200 MPa and ~105-115 MPa, alternatively active in time. For Phlegrean Fields, we evidence a progressive deepening of the shallow reservoirs, from the Campanian Ignimbrite (30-50 MPa) to the Monte Nuovo eruption (115 MPa). Only one eruption was studied for Ischia, the Cretaio eruption, that shows a reservoir at 140 MPa. The results on pressure are in large agreement with literature. The Cl geobarometer may help scientists to define the reservoir dynamics through time and provide strong constraints on pre-eruptive conditions, of utmost importance for the interpretation of the monitoring data and the identification of precursory signals.

  3. Analysis of long-period seismic waves excited by the May 18, 1980, eruption of Mount St. Helens - A terrestrial monopole

    NASA Technical Reports Server (NTRS)

    Kanamori, H.; Given, J. W.

    1982-01-01

    The eruption of Mount St. Helens on May 18, 1980, excited long-period seismic waves, and high-quality digital seismograms were recorded. The present investigation is concerned with the results of detailed analyses of Rayleigh and Love waves excited by this eruption. Since the elastic response of the earth is very accurately known, it is possible to retrieve the source parameters of this unique event from observations at far-field. It is shown that the source can be represented by a nearly horizontal single force. The conducted analysis is concerned with only long-period characteristics of the source. The short-period behavior of the source is difficult to determine from surface waves because the available knowledge of the earth's response is less accurate than at long periods.

  4. Identification and evolution of the juvenile component in 2004-2005 Mount St. Helens ash: Chapter 29 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Rowe, Michael C.; Thornber, Carl R.; Kent, Adam J.R.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Petrologic studies of volcanic ash are commonly used to identify juvenile volcanic material and observe changes in the composition and style of volcanic eruptions. During the 2004-5 eruption of Mount St. Helens, recognition of the juvenile component in ash produced by early phreatic explosions was complicated by the presence of a substantial proportion of 1980-86 lava-dome fragments and glassy tephra, in addition to older volcanic fragments possibly derived from crater debris. In this report, we correlate groundmass textures and compositions of glass, mafic phases, and feldspar from 2004-5 ash in an attempt to identify juvenile material in early phreatic explosions and to distinguish among the various processes that generate and distribute ash. We conclude that clean glass in the ash is derived mostly from nonjuvenile sources and is not particularly useful for identifying the proportion of juvenile material in ash samples. High Li contents (>30 μg/g) in feldspars provide a useful tracer for juvenile material and suggest an increase in the proportion of the juvenile component between October 1 and October 4, 2004, before the emergence of hot dacite on the surface of the crater on October 11, 2004. The presence of Li-rich feldspar out of equilibrium (based on Liplagioclase/melt partitioning) with groundmass and bulk dacite early in the eruption also suggests vapor enrichment in the initially erupted dacite. If an excess vapor phase was, indeed, present, it may have provided a catalyst to initiate the eruption. Textural and compositional comparisons between dome fault gouge and the ash produced by rockfalls, rock avalanches, and vent explosions indicate that the fault gouge is a likely source of ash particles for both types of events. Comparison of the ash from vent explosions and rockfalls suggests that the fault gouge and new dome were initially heterogeneous, containing a mixture of conduit and crater debris and juvenile material, but became increasingly

  5. Changing patterns of seismicity and ground deformation at the end of the Mount St. Helens 2004-2008 dome-building eruption

    NASA Astrophysics Data System (ADS)

    Lisowski, M.; Moran, S. C.; Dzurisin, D.; Anderson, K. R.

    2012-12-01

    The onset and character of the 2004-2008 dome-building eruption at Mount St. Helens has been reported in detail through 2006-2007; our purpose here is to describe activity near the end of the eruption in early 2008. Overall, seismicity, deformation, and extrusion rates progressively declined throughout the eruption. As measured from SEP, the continuously-running seismic station closest to the vent, the number of detected earthquakes declined from ~1000/day during January-October 2006 to hundreds per day by September 2007 and to near zero by late October 2007. Starting in December 2007 the seismicity rate increased slightly , culminating in a short-lived episode of about 500 events on January 12-13, most of which accompanied several tremor-like signals and a spasmodic burst of LPs. At this time, distinctive sawtooth-shaped tilt events that had accompanied dome growth ceased; these had been recorded throughout the earlier part of the eruption at three locations on the 1980s lava dome adjacent to the 2004-2008 vent. Seismicity rapidly declined back to rates of 10-20 per day for the next two weeks. The "last gasp" from the seismic perspective was on January 27-28, when a spasmodic burst of ~50 VT earthquakes occurred over the space of 3 hours early on January 27. This burst followed by a brief return of drumbeat-style earthquakes that had characterized much of the 2004-2008 eruption, with hybrid-style earthquakes occurring every 35-40 minutes through the end of January 28. By the end of January, seismicity had declined to 1-2 earthquakes per day, consistent with pre-2004-eruption background levels. In conjunction with the decline in seismicity rate, depths of locatable earthquakes increased from the 0-1 km depth range seen during the eruption to 2-3 km by the end of January 2008, a depth range typical of pre-2004-eruption seismicity. Remote-camera photography confirmed the cessation of dome growth and also the subsequent subsidence of the 2004-2008 dome as a result of

  6. Eruption in an ice-filled caldera, Mount Veniaminof, Alaska Peninsula: A section in The United States Geological Survey in Alaska: Accomplishments during 1983

    USGS Publications Warehouse

    Yount, M. Elizabeth; Miller, Thomas P.; Emanuel, Richard P.; Wilson, Frederic H.

    1985-01-01

    The more prominent of the two visible intracaldera cones of Mount Veniaminof went into eruption in early June 1983 and continued until early April 1984. Veniaminof is a 2,507-m-high composite cone having an 8 x 11-km summit caldera which formed 3,300-3,700 yr B.P. (Miller and Smith, 1977). The active 1.6x1.2-km cone protrudes 200 m through the glacial ice filling the caldera; it lies in a 60-m-long belt of cinder cones that is transverse to the trend of the Aleutian arc (fig. 44).

  7. Enhancement in stratospheric aerosols measured by laser sounding at l'Observatoire de Haute-Provence following the volcanic eruption of Mount Saint Helens

    NASA Astrophysics Data System (ADS)

    Lefrere, J.; Pelon, J.; Cahen, C.; Megie, G.; Flamant, P.

    1981-01-01

    An aerosol layer with scattering ratios larger than 10 at 532 nm has been observed in July 1980 above l'Observatoire de Haute-Provence (44 deg N, 6 deg E). This layer, located at 21.5 km with a vertical extension smaller than 1 km, is related to the injection of volcanic debris in the stratosphere after the Mount Saint Helens (46 deg N, 122 deg W) major eruptions of May 18 and May 25, 1980. The horizontal transport of the observed layers is analyzed in terms of the general stratospheric circulation. A maximum value of the vertical diffusion coefficient (0.01 sq m/sec) has been derived.

  8. In situ observations of aerosol and chlorine monoxide after the 1991 eruption of Mount Pinatubo - Effect of reactions on sulfate aerosol

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Jonsson, H. H.; Brock, C. A.; Toohey, D. W.; Avallone, L. M.; Baumgardner, D.; Dye, J. E.; Poole, L. R.; Woods, D. C.; Decoursey, R. J.

    1993-01-01

    Highly resolved aerosol size distributions measured from high-altitude aircraft can be used to describe the effect of the 1991 eruption of Mount Pinatubo on the stratospheric aerosol. In some air masses, aerosol mass mixing ratios increased by factors exceeding 100 and aerosol surface area concentrations increased by factors of 30 or more. Increases in aerosol surface area concentration were accompanied by increases in chlorine monoxide at mid-latitudes when confounding factors were controlled. This observation supports the assertion that reactions occurring on the aerosol can increase the fraction of stratospheric chlorine that occurs in ozone-destroying forms.

  9. Eruptive history, petrology, and petrogenesis of the Joe Lott Tuff Member of the Mount Belknap Volcanics, Marysvale volcanic field, west-central Utah

    USGS Publications Warehouse

    Budding, Karin E.

    1982-01-01

    The Joe Lott Tuff Member of the Mount Belknap Volcanics is the largest rhyolitic ash-flow tuff sheet in the Marysvale volcanic field. It was erupted 19 m.y. ago, shortly after the changeover from intermediate-composition calc-alkalic volcanism to bimodal basalt-rhyolite volcanism. Eruption of the tuff resulted in the formation of the Mount Belknap Caldera whose pyroclastic intracaldera stratigraphy parallels that in the outflow facies. The Joe Loft Tuff Member is a composite ash-flow sheet that changes laterally from a simple cooling unit near the source to four distinct cooling units toward the distal end. The lowest of these units is the largest and most widespread; it is 64 m thick and contains a basal vitrophyre. Eruption of the lower unit led to the initial collapse of the caldera. The lower unit is followed upward by a 43 m middle unit, a 26 m pink-colored unit which is separated by a prominent air- fall layer, and a 31 m upper unit. The Joe Loft Tuff Member is an alkali rhyolite with 75.85-77.31 wt. % silica and 8.06-9.32 wt. % K2O+Na2O; the agpaitic index (Na2O+ K2O/Al2O3) is .77-.98. The tuff contains about I% phenocrysts of quartz, sanidine, oligoclase, augite, apatite, zircon, sphene, biotite, and oxidized Fe-Ti oxides. The basal vitrophyre contains accessory allanite, chevkinite, and magnesiohastingsite. The main cooling units are chemically and mineralogically zoned indicating that the magma chamber restratified prior to each major eruption. Within each of the two thickest cooling units, the mineralogy changes systematically upwards; the Or content and relative volume of sanidine decreases and An content of plagioclase increases. The basal vitrophyre of the lower unit has a bulk composition that lies in the thermal trough near the minima of Or-Ab-Q at 1 kb PH2O. Microprobe analyses of feldspar and chemical modeling on experimental systems indicate that pre-eruption temperatures were near 750?C and that the temperature increased during the eruption of

  10. Effects of lava-dome growth on the crater glacier of Mount St. Helens, Washington: Chapter 13 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Walder, Joseph S.; Schilling, Steve P.; Vallance, James W.; LaHusen, Richard G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The process of lava-dome emplacement through a glacier was observed for the first time as the 2004-6 eruption of Mount St. Helens proceeded. The glacier that had grown in the crater since the cataclysmic 1980 eruption was split in two by the new lava dome. The two parts of the glacier were successively squeezed against the crater wall. Photography, photogrammetry, and geodetic measurements document glacier deformation of an extreme variety, with strain rates of extraordinary magnitude as compared to normal temperate alpine glaciers. Unlike such glaciers, the Mount St. Helens crater glacier shows no evidence of either speed-up at the beginning of the ablation season or diurnal speed fluctuations during the ablation season. Thus there is evidently no slip of the glacier over its bed. The most reasonable explanation for this anomaly is that meltwater penetrating the glacier is captured by a thick layer of coarse rubble at the bed and then enters the volcano’s groundwater system rather than flowing through a drainage network along the bed. Mechanical consideration of the glacier-squeeze process also leads to an estimate for the driving pressure applied by the growing lava dome.

  11. The initial phases of the 2008-2009 Mount Etna eruption: A multidisciplinary approach for hazard assessment

    NASA Astrophysics Data System (ADS)

    Bonaccorso, A.; Bonforte, A.; Calvari, S.; Del Negro, C.; di Grazia, G.; Ganci, G.; Neri, M.; Vicari, A.; Boschi, E.

    2011-03-01

    Between 2007 and early 2008, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) monitoring networks on Etna volcano recorded a recharging phase that climaxed with a new effusive eruption on 13 May 2008 and lasted about 14 months. A dike-forming intrusion was accompanied by a violent seismic swarm, with more than 230 events recorded in the first 6 h, the largest being ML = 3.9. In the meanwhile, marked ground deformation was recorded by the permanent tilt and GPS networks, and sudden changes in the summit area were detected by five continuously recording magnetic stations. Poor weather conditions did not allow direct observation of the eruptive events, but important information was provided by infrared satellite images that detected the start of lava fountains from the eruptive fissure, feeding a lava flow. This flow spread within the Valle del Bove depression, covering 6.4 km on the southeastern flank of the volcano in a few hours. The seismicity and deformation pattern indicated that the dike-forming intrusion was propagating northward. It produced a dry fracture field, which generated concern for the possibility that the eruptive fissures could expand downslope toward populated areas. Monitoring and modeling of the multidisciplinary data, together with the simulations of ash dispersal and lava flows, allowed us both to infer the eruptive mechanisms and to provide correct interpretation of the ongoing phenomena, furnishing useful information for civil defense purposes. We describe how this approach of feedback between monitoring and research provides critical support to risk evaluation.

  12. The roles of magmatic and external water in the March 8 tephra eruption at Mount St. Helens as assessed by a 1-D steady plume-height model

    NASA Astrophysics Data System (ADS)

    Mastin, L. G.; Sherrod, D. R.; Vallance, J. W.; Thornber, C. T.; Ewert, J. W.

    2005-12-01

    The dome-building eruption at Mount St. Helens has occurred through glacial ice and snow that would be expected to substantially affect the character of the eruption. Nevertheless, the role of water in the eruption to date has not always been clear. For example, on March 8, 2005, a half-hour-long tephra blast sent a plume to a maximum of ~9 km above the vent (based on pilot reports); seismicity and plume heights were greatest during the first ~10 minutes, then persisted for another ~15 minutes at a lower level before the eruption stopped. Tephra volume within 5 km2 downwind of the vent was ~5x104 m3 DRE, but trace amounts were reported at least to Ellensburg, WA (150 km NE), suggesting a total areal coverage >5,000 km2 and total volume >1x105 m3. Assuming that most of this material was expelled in the first ten minutes and had a density of 2500 kg/m3, the mass flow rate (M) during the vigorous phase was >~4x105 kg/s. The tephra, composed primarily of non-pumiceous broken and decrepitated dome rock, could have been expelled either by groundwater and steam at relatively modest (boiling-point) temperatures, or by magmatic gas at much higher temperatures. The high plume, however, suggested significant buoyancy, perhaps driven by temperatures closer to magmatic. To assess the effect of magmatic heat on plume height, we employ a 1-D steady volcanic plume model that uses specified vent diameter, exit velocity, eruption temperature, mass fractions of gas and added external water, and profiles of atmospheric temperature and humidity, to calculate plume height and plume properties as a function of elevation. The model considers the enthalpy of equilibrium water condensation and of ice formation. Model results show that, under atmospheric temperature and humidity profiles measured near Mount St. Helens on the afternoon of March 8, 2005, a plume height (h) of 7-9 km could have developed with eruption temperatures (T) as low as 100° C, provided the mass fraction of water vapor

  13. Bayesian inversion of data from effusive volcanic eruptions using physics-based models: Application to Mount St. Helens 2004--2008

    USGS Publications Warehouse

    Anderson, Kyle; Segall, Paul

    2013-01-01

    Physics-based models of volcanic eruptions can directly link magmatic processes with diverse, time-varying geophysical observations, and when used in an inverse procedure make it possible to bring all available information to bear on estimating properties of the volcanic system. We develop a technique for inverting geodetic, extrusive flux, and other types of data using a physics-based model of an effusive silicic volcanic eruption to estimate the geometry, pressure, depth, and volatile content of a magma chamber, and properties of the conduit linking the chamber to the surface. A Bayesian inverse formulation makes it possible to easily incorporate independent information into the inversion, such as petrologic estimates of melt water content, and yields probabilistic estimates for model parameters and other properties of the volcano. Probability distributions are sampled using a Markov-Chain Monte Carlo algorithm. We apply the technique using GPS and extrusion data from the 2004–2008 eruption of Mount St. Helens. In contrast to more traditional inversions such as those involving geodetic data alone in combination with kinematic forward models, this technique is able to provide constraint on properties of the magma, including its volatile content, and on the absolute volume and pressure of the magma chamber. Results suggest a large chamber of >40 km3 with a centroid depth of 11–18 km and a dissolved water content at the top of the chamber of 2.6–4.9 wt%.

  14. Evidence for degassing of fresh magma during the 2004-2008 eruption of Mount St. Helens: Subtle signals from the hydrothermal system

    NASA Astrophysics Data System (ADS)

    Bergfeld, Deborah; Evans, William C.; Spicer, Kurt R.; Hunt, Andrew G.; Kelly, Peter J.

    2017-09-01

    Results from chemical and isotopic analyses of water and gas collected between 2002 and 2016 from sites on and around Mount St. Helens are used to assess magmatic degassing related to the 2004-2008 eruption. During 2005 the chemistry of hot springs in The Breach of Mount St. Helens showed no obvious response to the eruption, and over the next few years, changes were subtle, giving only slight indications of perturbations in the system. By 2010 however, water chemistry, temperatures, and isotope compositions (δD and δ18O) clearly indicated some inputs of volatiles and heat associated with the eruption, but the changes were such that they could be attributed to a pre-existing, gas depleted magma. An increase of 1.5‰ in the δ13C values of dissolved carbon in the springs was noted in 2006 and continued through 2009, a change that was mirrored by a similar shift in δ13C-CO2 in bubble gas emissions. These changes require input of a new source of carbon to the hydrothermal system and provide clear evidence of CO2 from an undegassed body of magma. Rising trends in 3He/4He ratios in gas also accompanied the increases in δ13C. Since 2011 maximum RC/RA values are ≥ 6.4 and are distinctly higher than 5 samples collected between 1986 and 2002, and provide additional evidence for some involvement of new magma as early as 2006, and possibly earlier, given the unknown time needed for CO2 and He to traverse the system and arrive at the springs.

  15. Evidence for degassing of fresh magma during the 2004-2008 eruption of Mount St. Helens: Subtle signals from the hydrothermal system

    USGS Publications Warehouse

    Bergfeld, Deborah; Evans, William C.; Spicer, Kurt R.; Hunt, Andrew G.; Kelly, Peter

    2017-01-01

    Results from chemical and isotopic analyses of water and gas collected between 2002 and 2016 from sites on and around Mount St. Helens are used to assess magmatic degassing related to the 2004-2008 eruption. During 2005 the chemistry of hot springs in The Breach of Mount St. Helens showed no obvious response to the eruption, and over the next few years, changes were subtle, giving only slight indications of perturbations in the system. By 2010 however, water chemistry, temperatures, and isotope compositions (δD and δ18O) clearly indicated some inputs of volatiles and heat associated with the eruption, but the changes were such that they could be attributed to a pre-existing, gas depleted magma. An increase of ~ 1.5‰ in the δ13C values of dissolved carbon in the springs was noted in 2006 and continued through 2009, a change that was mirrored by a similar shift in δ13C-CO2 in bubble gas emissions. These changes require input of a new source of carbon to the hydrothermal system and provide clear evidence of CO2 from an undegassed body of magma. Rising trends in 3He/4He ratios in gas also accompanied the increases in δ13C. Since 2011 maximum RC/RA values are ≥ 6.4 and are distinctly higher than 5 samples collected between 1986 and 2002, and provide additional evidence for some involvement of new magma as early as 2006, and possibly earlier, given the unknown time needed for CO2 and He to traverse the system and arrive at the springs.

  16. Using the Mount Pinatubo Volcanic Eruption to Determine Climate Sensitivity: Comments on "Climate Forcing by the Volcanic Eruption of Mount Pinatubo" by David H. Douglass and Robert S. Knox

    SciTech Connect

    Wigley, T L; Ammann, C M; Santer, B D

    2005-04-22

    [1] Douglass and Knox [2005], hereafter referred to as DK, present an analysis of the observed cooling following the 1991 Mt. Pinatubo eruption and claim that these data imply a very low value for the climate sensitivity (equivalent to 0.6 C equilibrium warming for a CO{sub 2} doubling). We show here that their analysis is flawed and their results are incorrect.

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

    USGS Publications Warehouse

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

    2008-01-01

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

  18. Magnitude and timing of downstream channel aggradation and degradation in response to a dome-building eruption at Mount Hood, Oregon

    USGS Publications Warehouse

    Pierson, Thomas C.; Pringle, Patrick T.; Cameron, Kenneth A.

    2011-01-01

    A dome-building eruption at Mount Hood, Oregon, starting in A.D. 1781 and lasting until ca. 1793, produced dome-collapse lithic pyroclastic flows that triggered lahars and intermittently fed 108 m3 of coarse volcaniclastic sediment to sediment reservoirs in headwater canyons of the Sandy River. Mobilization of dominantly sandy sediment from these reservoirs by lahars and seasonal floods initiated downstream migration of a sediment wave that resulted in a profound cycle of aggradation and degradation in the lowermost reach of the river (depositional reach), 61-87 km from the source. Stratigraphic and sedimentologic relations in the alluvial fill, together with dendrochronologic dating of degradation terraces, demonstrate that (1) channel aggradation in response to sediment loading in the headwater canyons raised the river bed in this reach at least 23 m in a decade or less; (2) the transition from aggradation to degradation in the upper part of this reach roughly coincided with the end of the dome-building eruption; (3) fluvial sediment transport and deposition, augmented by one lahar, achieved a minimum average aggradation rate of ~2 m/yr; (4) the degradation phase of the cycle was more prolonged than the aggradation phase, requiring more than half a century for the river to reach its present bed elevation; and (5) the present longitudinal profile of the Sandy River in this reach is at least 3 m above the pre-eruption profile. The pattern and rate of channel response and recovery in the Sandy River following heavy sediment loading resemble those of other rivers similarly subjected to very large sediment inputs. The magnitude of channel aggradation in the lower Sandy River, greater than that achieved at other volcanoes following much larger eruptions, was likely enhanced by lateral confinement of the channel within a narrow incised valley. A combination of at least one lahar and winter floods from frequent moderate-magnitude rainstorms and infrequent very large

  19. Reduction of surface displacement by magma compressibility during the ongoing eruption of Mount St. Helens, and its implication for volcano monitoring

    NASA Astrophysics Data System (ADS)

    Mastin, L. G.; Lisowski, M.; Roeloffs, E.

    2006-12-01

    Geodetic changes are known to accompany volcanic unrest; yet the amplitude of these changes varies greatly from one volcano to another. At Mount St. Helens, geodetic displacements in the three months prior to the September 2004 eruption onset at the single operating continuous GPS station were less than the 3-mm seasonal variation. From September 2004 until August 2006, while >8×10^7 m3 magma erupted, the maximum radial deflation, at 5-10 km distance from the crater, totaled only ~3 cm. Source modeling of surface deformation over this time period indicates that the volume contraction of the magma reservoir was only ~1/3 the volume erupted. Why? Among other possibilities, we show here that, in an equant-shaped magma body, any significant bubble population reduces the ratio of reservoir-volume shrinkage to erupted volume. Consider a reservoir consisting of a cavity in an elastic host rock with volume V_C, pressure p, and compressibility κ _C=(1/V_C)(∂ V_C/∂ p) containing magma of density ρ _M and compressibility κ_M=(1/ρ _M)(∂ ρ _M/∂ p). Addition or withdrawal of a volume V_e of magma having density ρ_e results in a reservoir volume change dV_C=ρ _eV_e/(ρ _M(1+κ _M/κ _C)). For a spherical or prolate ellipsoidal reservoir situated within host rock of typical shear modulus G=~35 GPa, κ _C=3/(4G)=~2x10-11 Pa-1. By contrast, magma compressibility varies from ~2 to 90×10-11 Pa-1 for gas volume fractions v_g of 0 to 0.1 as bubbles expand and gas exsolves. Using the two-component gas solubility model VolatileCalc (Newman &Lowenstern, 2001, Comp. Geosci. 105:183-206) and reasonable St. Helens values of CO2=3000 ppm, H2O=5 wt%, crystallinity=45% and temperature=900°C, values of κ _M=2, 4.3, 7.1, 12, 55, and 90×10-11 Pa-1 are obtained for v_g=0, 0.005, 0.007, 0.01, 0.03, and 0.09 respectively. Thus when v_g=0.01, κ _M/κ _C=~6 and (for ρ _e=ρ _M) the volume change in the reservoir should be only about one seventh the intruded or extruded volume. The

  20. The Response of Ozone and Nitrogen Dioxide to the Eruption of Mount Pinatubo at Southern and Northern Midlatitudes

    NASA Technical Reports Server (NTRS)

    Aquila, Valentina; Oman, Luke D.; Stolarski, Richard S.; Douglass, Anne R.; Newman, Paul A.

    2013-01-01

    Observations have shown that the mass of nitrogen dioxide decreased at both southern and northern midlatitudes in the year following the eruption of Mt. Pinatubo, indicating that the volcanic aerosol had enhanced nitrogen dioxide depletion via heterogeneous chemistry. In contrast, the observed ozone response showed a northern midlatitude decrease and a small southern midlatitude increase. Previous simulations that included an enhancement of heterogeneous chemistry by the volcanic aerosol but no other effect of this aerosol produce ozone decreases in both hemispheres, contrary to observations. The authors simulations show that the heating due to the volcanic aerosol enhanced both the tropical upwelling and Southern Hemisphere extratropical downwelling. This enhanced extratropical downwelling, combined with the time of the eruption relative to the phase of the Brewer Dobson circulation, increased Southern Hemisphere ozone via advection, counteracting the ozone depletion due to heterogeneous chemistry on the Pinatubo aerosol.

  1. Field-trip guide to Mount St. Helens, Washington - An overview of the eruptive history and petrology, tephra deposits, 1980 pyroclastic density current deposits, and the crater

    USGS Publications Warehouse

    Pallister, John S.; Clynne, Michael A.; Wright, Heather M.; Van Eaton, Alexa R.; Vallance, James W.; Sherrod, David R.; Kokelaar, B. Peter

    2017-08-02

    This field trip will provide an introduction to several fascinating features of Mount St. Helens. The trip begins with a rigorous hike of about 15 km from the Johnston Ridge Observatory (9 km north-northeast of the crater vent), across the 1980 Pumice Plain, to Windy Ridge (3.6 km northeast of the crater vent) to examine features that document the dynamics and progressive emplacement of pyroclastic flows. The next day, we examine classic tephra outcrops of the past 3,900 years and observe changes in thickness and character of these deposits as we traverse their respective lobes. We examine clasts in the deposits and discuss how the petrology and geochemistry of Mount St. Helens deposits reveal the evolution of the magmatic system through time. We also investigate the stratigraphy of the 1980 blast deposit and review the chronology of this iconic eruption as we travel through the remains of the blown-down forest. The third day is another rigorous hike, about 13 km round trip, climbing from the base of Windy Ridge (elevation 1,240 m) to the front of the Crater Glacier (elevation 1,700 m). En route we examine basaltic andesite and basalt lava flows emplaced between 1,800 and 1,700 years before present, a heterolithologic flow deposit produced as the 1980 blast and debris avalanche interacted, debris-avalanche hummocks that are stranded on the north flank and in the crater mouth, and shattered dacite lava domes that were emplaced between 3,900 and 2,600 years before present. These domes underlie the northern part of the volcano. In addition, within the crater we traverse well-preserved pyroclastic-flow deposits that were emplaced on the crater floor during the summer of 1980, and a beautiful natural section through the 1980 deposits in the upper canyon of the Loowit River.Before plunging into the field-trip log, we provide an overview of Mount St. Helens geology, geochemistry, petrology, and volcanology as background. The volcano has been referred to as a

  2. Remote camera observations of lava dome growth at Mount St. Helens, Washington, October 2004 to February 2006: Chapter 11 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Poland, Michael P.; Dzurisin, Daniel; LaHusen, Richard G.; Major, John J.; Lapcewich, Dennis; Endo, Elliot T.; Gooding, Daniel J.; Schilling, Steve P.; Janda, Christine G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Images from a Web-based camera (Webcam) located 8 km north of Mount St. Helens and a network of remote, telemetered digital cameras were used to observe eruptive activity at the volcano between October 2004 and February 2006. The cameras offered the advantages of low cost, low power, flexibility in deployment, and high spatial and temporal resolution. Images obtained from the cameras provided important insights into several aspects of dome extrusion, including rockfalls, lava extrusion rates, and explosive activity. Images from the remote, telemetered digital cameras were assembled into time-lapse animations of dome extrusion that supported monitoring, research, and outreach efforts. The wide-ranging utility of remote camera imagery should motivate additional work, especially to develop the three-dimensional quantitative capabilities of terrestrial camera networks.

  3. Hydrogen isotope investigation of amphibole and glass in dacite magmas erupted in 1980-1986 and 2005 at Mount St. Helens, Washington

    USGS Publications Warehouse

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

    2013-01-01

    In active, shallow, sub-volcanic magma conduits the extent of the dehydrogenation–oxidation reaction in amphibole phenocrysts is controlled by energetic processes that cause crystal lattice damage or conditions that increase hydrogen diffusivity in magmatic phases. Amphibole phenocrysts separated from dacitic volcanic rocks erupted from 1980 to 1986 and in 2005 at Mount St. Helens (MSH) were analyzed for δD, water content and Fe3+/Fe2+, and fragments of glassy groundmass were analyzed for δD and water content. Changes in amphibole δD values through time are evaluated within the context of carefully observed volcanic eruption behavior and published petrological and geochemical investigations. Driving forces for amphibole dehydrogenation include increase in magma oxygen fugacity, decrease in amphibole hydrogen fugacity, or both. The phenocryst amphibole (δD value c. –57‰ and 2 wt % H2O) in the white fallout pumice of the May 18, 1980 plinian eruptive phase is probably little modified during rapid magma ascent up an ∼7 km conduit. Younger volcanic rocks incorporate some shallowly degassed dacitic magma from earlier pulses, based on amphibole phenocryst populations that exhibit varying degrees of dehydrogenation. Pyroclastic rocks from explosive eruptions in June–October 1980 have elevated abundances of mottled amphibole phenocrysts (peaking in some pyroclastic rocks erupted on July 22, 1980), and extensive amphibole dehydrogenation is linked to crystal damage from vesiculation and pyroclastic fountain collapse that increased effective hydrogen diffusion in amphibole. Multiple amphibole δD populations in many 1980 pyroclastic rocks combined with their groundmass characteristics (e.g. mixed pumice textures) support models of shallow mixing prior to, or during, eruption as new, volatile-rich magma pulses blended with more oxidized, degassed magma. Amphibole dehydrogenation is quenched at the top surface of MSH dacite lava lobes, but the diversity in the

  4. Changes in channel geometry of six eruption-affected tributaries of the Lewis River, 1980-82, Mount St. Helens, Washington

    USGS Publications Warehouse

    Martinson, H.A.; Finneran, S.D.; Topinka, L.J.

    1984-01-01

    The May 18, 1980, eruption of Mount St. Helens generated a lateral blast, lahars and tephra deposits that altered tributary channels in the Lewis River drainage basin. In order to assess potential flood hazards, study channel adjustments, and construct a sediment budget for the perturbed drainages on the east and southeast flanks of the volcano, channel cross sections were monumented and surveyed on Pine Creek, Muddy River, and Smith Creek during September and October of 1980. Additional cross sections were monumented and surveyed on Swift Creek, Bean Creek, and Clearwater Creek during the summer of 1981. The network of 88 channel cross sections has been resurveyed annually. Selected cross sections have been surveyed more frequently, following periods of higher flow. The repetitive cross-section surveys provide measurements of bank erosion or accretion and of channel erosion or aggradation. The report presents channel cross-section profiles constructed from the survey data collected during water years 1980-82. (USGS)

  5. Heterogeneous conversion of N{sub 2}O{sub 5} to HNO{sub 3} in the post-Mount Pinatubo eruption stratosphere

    SciTech Connect

    Rinsland, C.P.; Gunson, M.R.; Abrams, M.C.

    1994-04-20

    Simultaneous stratospheric volume mixing ratio (VMR) profiles of dinitrogen pentoxide (N{sub 2}O{sub 5}) and nitric acid HNO{sub 3} at sunrise between 25{degrees}N and 15{degrees}S latitude and profiles of HNO{sub 3} at sunset between 42{degrees}S and 53{degrees}S latitude have been derived from 0.01 cm{sup -1} resolution infrared solar occultation spectra recorded 9 {1/2} months after the massive eruption of the Mount Pinatubo volcano in the Philippine Islands. The measurements were obtained by the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 20 to April 2, 1992). The measured HNO{sub 3} VMRs are higher atmore » all altitudes and latitudes than corresponding values measured by the limb infrared monitor of the stratosphere (LIMS) instrument during the same season in 1979, when the aerosol loading was near background levels. The largest relative increase in the HNO{sub 3} VMR occurred near the equator at 30-km altitude, where the ATMOS/ATLAS 1 values are about a factor of 2 higher than the LIMS measurements. Two-dimensional model calculations show that the increase in HNO{sub 3} and the ATMOS/ATLAS 1 measurement of a steep decrease in the N{sub 2}O{sub 5} to HNO{sub 3} on the surfaces of the Mount Pinatubo sulfate aerosols. Our profile results demonstrate the global impact of the N{sub 2}O{sub 5} + H{sub 2}0 {r_arrow} 2HNO{sub 3} heterogeneous reaction in altering the partitioning of stratospheric odd nitrogen after a major volcanic eruption. 40 refs., 6 figs., 2 tabs.« less

  6. Radar interferometry observations of surface displacements during pre- and coeruptive periods at Mount St. Helens, Washington, 1992-2005: Chapter 18 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Poland, Michael; Lu, Zhong; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    We analyzed hundreds of interferograms of Mount St. Helens produced from radar images acquired by the ERS-1/2, ENVISAT, and RADARSAT satellites during the 1992-2004 preeruptive and 2004-2005 coeruptive periods for signs of deformation associated with magmatic activity at depth. Individual interferograms were often contaminated by atmospheric delay anomalies; therefore, we employed stacking to amplify any deformation patterns that might exist while minimizing random noise. Preeruptive interferograms show no signs of volcanowide deformation between 1992 and the onset of eruptive activity in 2004. Several patches of subsidence in the 1980 debris-avalanche deposit were identified, however, and are thought to be caused by viscoelastic relaxation of loosely consolidated substrate, consolidation of water-saturated sediment, or melting of buried ice. Coeruptive interferometric stacks are dominated by atmospheric noise, probably because individual interferograms span only short time intervals in 2004 and 2005. Nevertheless, we are confident that at least one of the seven coeruptive stacks we constructed is reliable at about the 1-cm level. This stack suggests deflation of Mount St. Helens driven by contraction of a source beneath the volcano.

  7. Changes in seismic velocity during the first 14 months of the 2004–2008 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Hotovec-Ellis, A.J.; Vidale, J.E.; Gomberg, Joan S.; Thelen, Weston A.; Moran, Seth C.

    2015-01-01

    Mount St. Helens began erupting in late 2004 following an 18 year quiescence. Swarms of repeating earthquakes accompanied the extrusion of a mostly solid dacite dome over the next 4 years. In some cases the waveforms from these earthquakes evolved slowly, likely reflecting changes in the properties of the volcano that affect seismic wave propagation. We use coda-wave interferometry to quantify small changes in seismic velocity structure (usually <1%) between two similar earthquakes and employed waveforms from several hundred families of repeating earthquakes together to create a continuous function of velocity change observed at permanent stations operated within 20 km of the volcano. The high rate of earthquakes allowed tracking of velocity changes on an hourly time scale. Changes in velocity were largest near the newly extruding dome and likely related to shallow deformation as magma first worked its way to the surface. We found strong correlation between velocity changes and the inverse of real-time seismic amplitude measurements during the first 3 weeks of activity, suggesting that fluctuations of pressure in the shallow subsurface may have driven both seismicity and velocity changes. Velocity changes during the remainder of the eruption likely result from a complex interplay of multiple effects and are not well explained by any single factor alone, highlighting the need for complementary geophysical data when interpreting velocity changes.

  8. On the mechanism of explosive eruption of mount erebus volcano: the dynamics of the rupture structure in a cavitating layer

    NASA Astrophysics Data System (ADS)

    Bol'shakova, E. S.; Kedrinskiy, V. K.

    2016-10-01

    This paper presents the results of an experimental simulation of rupture development in heavily cavitating magma melt flow in volcanic conduits and its effect on the structure of explosive volcanic eruptions. The dynamics of the state of a layer of distilled water (similar in the density of cavitation nuclei to magma melt) under shock-wave loading was studied. The experiments were performed using electromagnetic hydrodynamic shock tubes (EM HST) with maximum capacitor bank energy of up to 100 J and 5 kJ. It was found that the topology of the rupture formed on the membrane surface did not change during its development. Empirical estimates were obtained for the proportion of the capacitor bank energy expended in the development of the rupture and the characteristic time of its existence. The study revealed a number of fundamentally new physical effects in the cavity dynamics in a cavitating medium: a cavitation “boundary layer” is formed on the surface of the quasi-empty rupture, which is transformed into a cluster of high energy density upon closure of the flow.

  9. The initial giant umbrella cloud of the May 18th, 1980, explosive eruption of Mount St. Helens

    USGS Publications Warehouse

    Sparks, R.S.J.; Moore, J.G.; Rice, C.J.

    1986-01-01

    The initial eruption column of May 18th, 1980 reached nearly 30 km altitude and released 1017 joules of thermal energy into the atmosphere in only a few minutes. Ascent of the cloud resulted in forced intrusion of a giant umbrella-shaped cloud between altitudes of 10 and 20 km at radial horizontal velocities initially in excess of 50 m/s. The mushroom cloud expanded 15 km upwind, forming a stagnation point where the radial expansion velocity and wind velocity were equal. The cloud was initiated when the pyroclastic blast flow became buoyant. The flow reduced its density as it moved away from the volcano by decompression, by sedimentation, and by mixing with and heating the surrounding air. Observations indicate that much of the flow, covering an area of 600 km2, became buoyant within 1.5 minutes and abruptly ascended to form the giant cloud. Calculations are presented for the amount of air that must have been entrained into the flow to make it buoyant. Assuming an initial temperature of 450??C and a magmatic origin for the explosion, these calculations indicate that the flow became buoyant when its temperature was approximately 150??C and the flow consisted of a mixture of 3.25 ?? 1011 kg of pyroclasts and 5.0 ?? 1011 kg of air. If sedimentation is considered, these figures reduce to 1.1 ?? 1011 kg of pyroclasts and 1.0 ?? 1011 kg of air. ?? 1986.

  10. 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.

  11. Physics-based conduit models of dome extrusion: Steady-state solutions applied to the Mount St. Helens 2004-2008 eruption

    NASA Astrophysics Data System (ADS)

    Wong, Y. Q.; Segall, P.; Anderson, K. R.; Bradley, A. M.

    2016-12-01

    Physics-based models of volcanic eruptions allow us to integrate diverse volcanological datasets to constrain important parameters of magmatic systems and to track its evolution during ascent. We have extended the 1D cylindrical conduit model of Anderson and Segall [2011] to include equilibrium crystallization, and vertical and lateral gas loss from the magma. Excess pressure in the magma chamber drives Newtonian flow until the viscous resistance to flow exceeds the rate-dependent frictional strength on the conduit wall, when magma transitions from viscous to plug flow. We investigate steady-state solutions to compare with the quasi-steady dome growth phase of Mount St. Helens between March and December 2005, and take magma chamber pressure, initial water content, permeability, conduit radius and friction coefficient as unknown model parameters. By including crystallization and gas loss, we can link physical datasets such as ground deformation and extrusion flux with petrological and gas flux data. Specifically, the model parameters influence dome rock porosity estimated from hand samples, extrusion rate from photogrammetry, plug depth from drumbeat earthquakes, and crystallization pressure from petrologic data. Model sensitivity tests show that changes that promote higher shear stress along the conduit walls, such as higher chamber pressure and conduit radius, as well as changes that retain more gas in the system, such as higher water content and percolation threshold, tend to increase dome porosity and exit velocity. Changes in permeability produce non-monotonic behavior in the predicted data due to the competing processes of gas exsolution and gas loss. Using this physics-based model in a Bayesian inversion, we estimate probability density functions of the model parameters and their correlations. Future work will investigate the time-dependent system, allowing us to incorporate time-evolving geodetic and eruption rate data into the inversion.

  12. Effects of the Mount Pinatubo eruption on the radiative and chemical processes in the troposphere and stratosphere

    NASA Technical Reports Server (NTRS)

    Kinnison, Douglas E.; Grant, Keith E.; Connell, Peter S.; Wuebbles, Donald J.

    1994-01-01

    The Lawrence Livermore National Laboratory two-dimensional zonally-averaged chemical-radiative-transport model of the global atmosphere was used to study the effects of the 15 June 1991 eruption of the Mt. Pinatubo volcano on stratospheric processes. SAGE 2 time-dependent aerosol surface area density and optical extinction data were used as input into the model. By 22 December 1991, a maximum equatorial change of -1.8 percent in column ozone was derived from heterogeneous chemical processes that convert NO(x) into HNO3 on sulfuric acid aerosols. Radiative feedbacks from increased aerosol optical thickness independently changes column ozone by approximately -3.5 percent for the same period. This occurs from increasing the net heating of the lower stratosphere, which indirectly increases chemical reaction rates via their temperature dependence and from changes in actinic fluxes, which directly modify photodissociation rates. Including both heterogeneous and radiative effects changes column ozone by -5.5 percent. The model-derived change overestimates the decrease in column ozone relative to the TOMS instrument on the Nimbus 7 satellite. Maximum local ozone decreases of 12 percent were derived in the equatorial region, at 25 km. Model-derived column NO2 peaked (-14 percent) at 30 deg S in October 1991. The timing of the NO2 peak is consistent with observation, but the model underestimates the magnitude of the decrease. Local concentrations of NO(x) (NO + NO2), ClO(x) (Cl + ClO), and HO(x) (OH + HO2), in the lower stratosphere between 30 deg S and 30 deg N, were calculated to have changed by -40 percent, +100 to +160 percent, and +120 to +140 percent respectively.

  13. Amphibole as an archivist of magmatic crystallization conditions: problems, potential, and implications for inferring magma storage prior to the paroxysmal 2010 eruption of Mount Merapi, Indonesia

    NASA Astrophysics Data System (ADS)

    Erdmann, Saskia; Martel, Caroline; Pichavant, Michel; Kushnir, Alexandra

    2014-06-01

    Amphibole is widely employed to calculate crystallization temperature and pressure, although its potential as a geobarometer has always been debated. Recently, Ridolfi et al. (Contrib Mineral Petrol 160:45-66, 2010) and Ridolfi and Renzulli (Contrib Mineral Petrol 163:877-895, 2012) have presented calibrations for calculating temperature, pressure, fO2, melt H2O, and melt major and minor oxide composition from amphibole with a large compositional range. Using their calibrations, we have (i) calculated crystallization conditions for amphibole from eleven published experimental studies to examine the problems and the potential of the new calibrations; and (ii) calculated crystallization conditions for amphibole from basaltic-andesitic pyroclasts erupted during the paroxysmal 2010 eruption of Mount Merapi in Java, Indonesia, to infer pre-eruptive conditions. Our comparison of experimental and calculated values shows that calculated crystallization temperatures are reasonable estimates. Calculated fO2 and melt SiO2 content yields potentially useful estimates at moderately reduced to moderately oxidized conditions and intermediate to felsic melt compositions. However, calculated crystallization pressure and melt H2O content are untenable estimates that largely reflect compositional variation in the crystallizing magmas and crystallization temperature and not the calculated parameters. Amphibole from Merapi's pyroclasts yields calculated conditions of ~200-800 MPa, ~900-1,050 °C, ~NNO + 0.3-NNO + 1.1, ~3.7-7.2 wt% melt H2O, and ~58-71 wt% melt SiO2. We interpret the variations in calculated temperature, fO2, and melt SiO2 content as reasonable estimates, but conclude that the large calculated pressure variation for amphibole from Merapi and many other arc volcanoes is evidence for thorough mixing of mafic to felsic magmas and not necessarily evidence for crystallization over a large depth range. In contrast, bimodal pressure estimates obtained for other arc magmas

  14. Channel geometry and hydrologic data for six eruption-affected tributaries of the Lewis River, Mount St. Helens, Washington, water years 1983-84

    USGS Publications Warehouse

    Martinson, H.A.; Hammond, H.E.; Mast, W.W.; Mango, P.D.

    1986-01-01

    The May 18, 1980, eruption of Mount St. Helens generated a lateral blast, lahars, and tephra deposits that altered stream channels in the Lewis River drainage basin. In order to assess potential flood hazards, monitor channel adjustments, and construct a sediment budget for disturbed drainages on the east and southeast flanks of the volcano, channel cross sections were monumented and surveyed on Pine Creek, Muddy River, and Smith Creek during September and October of 1980. Additional cross sections were monumented and surveyed on Swift Creek, Bean Creek , and Clearwater Creek during 1981. This network of channel cross sections has been resurveyed annually. Selected cross sections have been surveyed more frequently, following periods of higher flow. Longitudinal stream profiles of the low-water thalweg and (or) water surfaces were surveyed periodically for selected short reaches of channel. Corresponding map views for these reaches were constructed using the survey data and aerial photographs. This report presents plots of channel cross-section profiles, longitudinal stream profiles, and channel maps constructed from survey data collected during water years 1983-84. (USGS)

  15. Self-similar rupture implied by scaling properties of volcanic earthquakes occurring during the 2004-2008 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Harrington, Rebecca M.; Kwiatek, Grzegorz; Moran, Seth C.

    2015-01-01

    We analyze a group of 6073 low-frequency earthquakes recorded during a week-long temporary deployment of broadband seismometers at distances of less than 3 km from the crater at Mount St. Helens in September of 2006. We estimate the seismic moment (M0) and spectral corner frequency (f0) using a spectral ratio approach for events with a high signal-to-noise (SNR) ratio that have a cross-correlation coefficient of 0.8 or greater with at least five other events. A cluster analysis of cross-correlation values indicates that the group of 421 events meeting the SNR and cross-correlation criteria forms eight event families that exhibit largely self-similar scaling. We estimate the M0 and f0 values of the 421 events and calculate their static stress drop and scaled energy (ER/M0) values. The estimated values suggest self-similar scaling within families, as well as between five of eight families (i.e.,  and  constant). We speculate that differences in scaled energy values for the two families with variable scaling may result from a lack of resolution in the velocity model. The observation of self-similar scaling is the first of its kind for such a large group of low-frequency volcanic tectonic events occurring during a single active dome extrusion eruption.

  16. Dynamics of seismogenic volcanic extrusion resisted by a solid surface plug, Mount St. Helens, 2004-2005: Chapter 21 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

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

    2008-01-01

    The 2004-5 eruption of Mount St. Helens exhibited sustained, near-equilibrium behavior characterized by nearly steady extrusion of a solid dacite plug and nearly periodic occurrence of shallow earthquakes. Diverse data support the hypothesis that these earthquakes resulted from stick-slip motion along the margins of the plug as it was forced incrementally upward by ascending, solidifying, gas-poor magma. I formalize this hypothesis with a mathematical model derived by assuming that magma enters the base of the eruption conduit at a steady rate, invoking conservation of mass and momentum of the magma and plug, and postulating simple constitutive equations that describe magma and conduit compressibilities and friction along the plug margins. Reduction of the model equations reveals a strong mathematical analogy between the dynamics of the magma-plug system and those of a variably damped oscillator. Oscillations in extrusion velocity result from the interaction of plug inertia, a variable upward force due to magma pressure, and a downward force due to the plug weight. Damping of oscillations depends mostly on plug-boundary friction, and oscillations grow unstably if friction exhibits rate weakening similar to that observed in experiments. When growth of oscillations causes the extrusion rate to reach zero, however, gravity causes friction to reverse direction, and this reversal instigates a transition from unstable oscillations to self-regulating stick-slip cycles. The transition occurs irrespective of the details of rate-weakening behavior, and repetitive stick-slip cycles are, therefore, robust features of the system’s dynamics. The presence of a highly compressible elastic driving element (that is, magma containing bubbles) appears crucial for enabling seismogenic slip events to occur repeatedly at the shallow earthquake focal depths (8 N. These results imply that the system’s self-regulating behavior is not susceptible to dramatic change--provided that the

  17. Field-trip guide for exploring pyroclastic density current deposits from the May 18, 1980, eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Brand, Brittany D.; Pollock, Nicholas; Sarocchi, Damiano; Dufek, Josef; Clynne, Michael A.

    2017-07-05

    Pyroclastic density currents (PDCs) are one of the most dangerous phenomena associated with explosive volcanism. To help constrain damage potential, a combination of field studies, laboratory experiments, and numerical modeling are used to establish conditions that influence PDC dynamics and depositional processes, including runout distance. The objective of this field trip is to explore field relations that may constrain PDCs at the time of emplacement.The PDC deposits from the May 18, 1980, eruption of Mount St. Helens are well exposed along the steep flanks (10–30° slopes) and across the pumice plain (5–12° slopes) as far as 8 km north of the volcano. The pumice plain deposits represent deposition from a series of concentrated PDCs and are primarily thick (3–12 m), massive, and poorly sorted. In contrast, the steep east-flank deposits are stratified to cross-stratified, suggesting deposition from PDCs where turbulence strongly influenced transport and depositional processes.The PDCs that descended the west flank were largely nondepositional; they maintained a higher flow energy and carrying capacity than PDCs funneled through the main breach, as evidenced by the higher concentration of large blocks in their deposits. The PDC from the west flank collided with PDCs funneled through the breach at various points along the pumice plain. Evidence for flow collision will be explored and debated throughout the field trip.Evidence for substrate erosion and entrainment is found (1) along the steep eastern flank of the volcano, which has a higher degree of rough, irregular topography relative to the west flanks where PDCs were likely nonerosive, (2) where PDCs encountered debris-avalanche hummocks across the pumice plain, and (3) where PDCs eroded and entrained material deposited by PDCs produced during earlier phases of the eruption. Two features interpreted as large-scale (tens of meters wide) levees and a large (~200 m wide) channel scour-and-fill feature

  18. U-Th isotopes provide insights into the build-up to the 7.7 ka climactic eruption of Mount Mazama, Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Bosket, M. E.; Johnson, C.; Beard, B. L.; Bacon, C. R.

    2011-12-01

    Uranium-series isotope ratios determined on 35 whole-rock powders and 4 glass separates from preclimactic, climactic, and postcaldera volcanic rocks erupted from ~36 ka-4.8 ka at Mount Mazama, Crater Lake, Oregon identify both 230Th-excess and 238U-excess components. U-Th isotope ratios cover a very wide range of compositions, exceeding that yet measured for the entire Cascade arc. Age-corrected (230Th/232Th) and (238U/232Th) activity ratios range from 1.113-1.464 and 0.878-1.572 (44.4% 230Th-excess to 8.8% 238U-excess), respectively. These data identify a much stronger crustal influence than has previously been documented at Mount Mazama, and differentiate between lower crustal and upper crustal histories. The most distinctive aspect of our data is the contrast in 230Th-238U-232Th isotope ratios between low- and high-Sr (LSr, HSr) components identified by previous work, where the preclimactic/climactic LSr component exclusively contains 238U-excess (<1-8.8%) vs. the HSr component, as well as more primitive regional lavas, that are marked by 230Th-excess (2.6-44.4%). 230Th-excesses such as those we have recorded at Crater Lake are commonly observed in the Cascades. Melting-models suggest that the high 230Th-excess observed in the more primitive lavas probably involved an initial mantle melt of garnet lherzolite ((238U/232Th)=1.05), followed by mixing with a partial melt of a garnet-rich lower crustal composition (e.g. garnet amphibolite; (238U/232Th)=1.30). The presence of garnet is necessary in both the mantle and lower crust to explain the large 230Th-excesses. The extent of 238U-excess at Crater Lake has not yet been observed in Cascade volcanoes. At Crater Lake, 238U-excess occurs in more than half of the samples analyzed in this study. Traditionally, 238U-excess in arc magmas has been interpreted to record slab-fluid fluxing, but this is unlikely in the Cascade arc, because other isotopic and trace element data suggest a relatively minor role for slab

  19. 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.

  20. Interrelations among pyroclastic surge, pyroclastic flow, and lahars in Smith Creek valley during first minutes of 18 May 1980 eruption of Mount St. Helens, USA

    USGS Publications Warehouse

    Brantley, S.R.; Waitt, R.B.

    1988-01-01

    A devastating pyroclastic surge and resultant lahars at Mount St. Helens on 18 May 1980 produced several catastrophic flowages into tributaries on the northeast volcano flank. The tributaries channeled the flows to Smith Creek valley, which lies within the area devastated by the surge but was unaffected by the great debris avalanche on the north flank. Stratigraphy shows that the pyroclastic surge preceded the lahars; there is no notable "wet" character to the surge deposits. Therefore the lahars must have originated as snowmelt, not as ejected water-saturated debris that segregated from the pyroclastic surge as has been inferred for other flanks of the volcano. In stratigraphic order the Smith Creek valley-floor materials comprise (1) a complex valley-bottom facies of the pyroclastic surge and a related pyroclastic flow, (2) an unusual hummocky diamict caused by complex mixing of lahars with the dry pyroclastic debris, and (3) deposits of secondary pyroclastic flows. These units are capped by silt containing accretionary lapilli, which began falling from a rapidly expanding mushroom-shaped cloud 20 minutes after the eruption's onset. The Smith Creek valley-bottom pyroclastic facies consists of (a) a weakly graded basal bed of fines-poor granular sand, the deposit of a low-concentration lithic pyroclastic surge, and (b) a bed of very poorly sorted pebble to cobble gravel inversely graded near its base, the deposit of a high-concentration lithic pyroclastic flow. The surge apparently segregated while crossing the steep headwater tributaries of Smith Creek; large fragments that settled from the turbulent surge formed a dense pyroclastic flow along the valley floor that lagged behind the front of the overland surge. The unusual hummocky diamict as thick as 15 m contains large lithic clasts supported by a tough, brown muddy sand matrix like that of lahar deposits upvalley. This unit contains irregular friable lenses and pods meters in diameter, blocks incorporated from

  1. Hot pressing and lithification of gouge during the Mount St. Helens 2004-2008 eruption: insights from high temperature deformation experiments

    NASA Astrophysics Data System (ADS)

    Ryan, Amy G.; Russell, James K.; Heap, Michael J.

    2017-04-01

    We present results from an experimental program designed to investigate the timescales, conditions and mechanisms responsible for the densification and lithification of volcanic gouge at Mount St. Helens (MSH). From 2004-2008, MSH produced a series of lava domes/spines that were mantled by thick layers of gouge resulting from fracturing and cataclasis at the conduit-wall rock interface. The gouge comprises fine crystal-rich rock powder containing little to no glass. The erupted gouge carapace is texturally diverse, and varies from loose granular material to moderately indurated coherent rock to fine-grained cataclasite within tens of centimeters. The spatial association of these materials suggests that the originally unconsolidated conduit-fault gouge is densified and lithified during ascent to the surface. At present the conditions, timescales and mechanisms for lithification of the glass-poor materials are unknown. Here, we present results from a series of high-temperature (T) uniaxial deformation experiments performed on natural gouge collected from MSH (spine 5). The experiments are intended to (1) establish the feasibility of experimentally densifying/lithifying natural gouge materials at laboratory conditions approximating those within the MSH conduit, and to (2) constrain the effects of T, load and time on the extents, rates and mechanisms of densification. Our experimental conditions include T up to 800°C (T

  2. Instrumentation in remote and dangerous settings; examples using data from GPS “spider” deployments during the 2004-2005 eruption of Mount St. Helens, Washington: Chapter 16 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    LaHusen, Richard G.; Swinford, Kelly J.; Logan, Matthew; Lisowski, Michael; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Self-contained, single-frequency GPS instruments fitted on lightweight stations suitable for helicopter-sling payloads became a critical part of volcano monitoring during the September 2004 unrest and subsequent eruption of Mount St. Helens. Known as “spiders” because of their spindly frames, the stations were slung into the crater 29 times from September 2004 to December 2005 when conditions at the volcano were too dangerous for crews to install conventional equipment. Data were transmitted in near-real time to the Cascades Volcano Observatory in Vancouver, Washington. Each fully equipped unit cost about $2,500 in materials and, if not destroyed by natural events, was retrieved and redeployed as needed. The GPS spiders have been used to track the growth and decay of extruding dacite lava (meters per day), thickening and accelerated flow of Crater Glacier (meters per month), and movement of the 1980-86 dome from pressure and relaxation of the newly extruding lava dome (centimeters per day).

  3. Land use cover changes and water quality of Cipunten Agung Watershed Banten

    NASA Astrophysics Data System (ADS)

    Karima, Afifa; Leonardus Kaswanto, Regan

    2017-01-01

    In general, the land and natural resources utilization of Cipunteng Agung Watershed could be classified into protected and cultivated region. Based on satellite imagery classification, protected region covers 885.76 ha (22.71%), while cultivated region occupied 3,041.69 ha (77.29%) in 2011. It means that the land use and covers change (LUCC) to be cultivated rapidly increase. Those conditions had impacted positively to the local economy development, however it had negatively degrades water quality in Ciputen Agung river. Therefore, the purpose of this research is to analyze LUCC impacts to the water quality (WQ) in Cipunten Agung watershed. Supervised classification method and Water Pollution Index (WPI) approach were correlated to define the optimal solution to reduce the rate of LUCC. The result shows that area of cultivation tree and paddy field are higher than others in midstream, and settlement is higher in downstream, particularly at riparian landscapes. The concentration of total phospate, nitrite, and nitrate which indicated from agriculture land were complies with WPI class 2 until 4 standart. The rate of LUCC of Cipunten Agung watershed and the density of settlement are potential to be the driving factor of water quality degradation. Regional planning with ecology approach was recommended for sustainable development of Cipunten Agung Wateshed.

  4. Contrasting styles of Mount Vesuvius activity in the period between the Avellino and Pompeii Plinian eruptions, and some implications for assessment of future hazards

    NASA Astrophysics Data System (ADS)

    Andronico, Daniele; Cioni, Raffaello

    2002-09-01

    Intense explosive activity occurred repeatedly at Vesuvius during the nearly 1,600-year period between the two Plinian eruptions of Avellino (3.5 ka) and Pompeii (79 A.D.). By correlating stratigraphic sections from more than 40 sites around the volcano, we identify the deposits of six main eruptions (AP1-AP6) and of some minor intervening events. Several deposits can be traced up to 20 km from the vent. Their stratigraphic and dispersal features suggest the prevalence of two main contrasting eruptive styles, each involving a complex relationship between magmatic and phreatomagmatic phases. The two main eruption styles are (1) sub-Plinian to phreato-Plinian events (AP1 and AP2 members), where deposits consist of pumice and scoria fall layers alternating with fine-grained, vesiculated, accretionary lapilli-bearing ashes; and (2) mixed, violent Strombolian to Vulcanian events (AP3-AP6 members), which deposited a complex sequence of fallout, massive to thinly stratified, scoria-bearing lapilli layers and fine ash beds. Morphology and density variations of the juvenile fragments confirm the important role played by magma-water interaction in the eruptive dynamics. The mean composition of the ejected material changes with time, and shows a strong correlation with vent position and eruption style. The ranges of intensity and magnitude of these events, derived by estimations of peak column height and volume of the ejecta, are significantly smaller than the values for the better known Plinian and sub-Plinian eruptions of Vesuvius, enlarging the spectrum of the possible eruptive scenarios at Vesuvius, useful in the assessment of its potential hazard.

  5. Modeling of the thermal state of Mount Vesuvius from 1631 A.D. to present and the role of CO2 degassing on the volcanic conduit closure after the 1944 A.D. eruption

    NASA Astrophysics Data System (ADS)

    Quareni, Francesca; Moretti, Roberto; Piochi, Monica; Chiodini, Giovanni

    2007-03-01

    The last eruptive event at Mount Vesuvius occurred in 1944 A.D., ending a cycle of continuous eruptive activity started with the sub-Plinian event of 1631 A.D. The aim of this research is (1) to model the thermal evolution of the volcanic system from 1631 A.D. up to the present and (2) to investigate the possible process leading the volcano to the current state of quiescence. A finite element software is employed to solve the time-dependent energy equation and obtain the thermal field in the volcanic edifice and the surrounding medium. Volcanological, petrological, and geophysical constraints are used to define the crustal structure beneath the volcanic edifice, the magma supply system active since 1631 A.D., and the physico-chemical conditions of magma. Thermodynamic properties of magma and wall rocks have been evaluated from well-established thermo-chemical compilations and data from the literature. It is shown that heat transfer due to magma degassing is required in addition to the heat conduction in order to obtain transient depth-temperature fields consistent with geochemical observations, high crustal magnetization, and rigid behavior of the shallow crust as indicated by geophysical data. Surface data of carbon dioxide soil flux coming out from the Mount Vesuvius crater are taken to constrain such an additional heat flux. The agreement between modeled and measured temperatures at the crater since 1944 A.D. proves the consistency of the model. It is concluded that the present state of quiescence of Mount Vesuvius is mostly a consequence of the absence of magma supply from the deep reservoir into the shallower system. This allows the cooling of residual magma left within the volcanic conduit and the transition from continuous eruptive activity to the condition of conduit obstruction. In this scenario, the hydrothermal system may have developed subsequent to the cooling of the magma within the conduit. Our findings are a direct consequence of the high

  6. Fine Resolution Analysis of Lake Malawi Sediment Record Shows No Significant Climatic Impacts from the Mount Toba Super-Eruption of ~75ky

    NASA Astrophysics Data System (ADS)

    Jackson, L. J.; Stone, J.; Cohen, A. S.

    2014-12-01

    Debate over long, and short-term climatic impacts of the Mt. Toba super-eruption circa 75ky is often focused on East Africa. A severe drop in anatomically modern human populations has been hypothesized to be synchronous with a volcanic winter caused by the Toba super-eruption. If the Toba eruption caused a volcanic winter in East Africa, climatologically-sensitive ecosystems, such as Lake Malawi and its immediate watershed should show a direct and observable response in the sediment record. Cooler temperatures would cause a reduction of density contrast between epilimnion and hypolimnion waters, allowing for increased mixing and oxygenation of normally anoxic bottom waters. Enhanced mixing would cause noticeable changes in lake fly and algal communities. Cooler temperatures might also affect precipitation and the fire regime in the surrounding watershed. We analyzed two Lake Malawi cores at the finest practical resolution. Core 2A-10H-2 was analyzed in less than 6-year intervals and core 1C-8H-1 in 7-year intervals surrounding the Youngest Toba Tephra (YTT) for microfaunal abundance and variability, sediment composition, and evidence of changes in the occurrence of fires or watershed precipitation. Our analysis included point counts of diatoms and other algae, lake flies, charcoal, and siliciclastics. Changes in microfossil assemblage, variability, and abundance, as well as sediment composition around the YTT in Core 2A and 1C do not indicate that increased mixing or cooler temperatures occurred in either the central or northern basins of Lake Malawi. Similarly, charcoal counts do not suggest a change in fire regime. Our results indicate that at a subdecadal scale there was no substantial response in Lake Malawi or its immediate watershed to the Mt. Toba super-eruption, in contrast to predictions from the volcanic winter hypothesis.

  7. Land Use Cover Changes and Run Off Potention of Cipunten Agung Watershed Banten

    NASA Astrophysics Data System (ADS)

    Karima, A.; Kaswanto, R. L.

    2017-10-01

    The changes of landscape form such as Land Use Cover Changes (LUCC) of Cipunten Agung watershed could be identified periodically in 1995, 2005, and 2015. In general, land utilization in Cipunten Agung classified into protected region and cultivated region. In 2011, total of protected area is 885.80 ha or 22.54% of watershed area. Those conditions affected both positively to the community development and negatively to the water quantity condition in Cipunten Agung such as flooding, run off, and erosion. Therefore, the purpose of this research is to analyze LUCC impacts to run off potential in Cipunten Agung watershed. Supervised classification method and Soil Conservation Services (Qscs) approach were correlated to determine the figure out an optimal solution to reduce the rate of LUCC. Cipunten Agung watershed imagery was classified into five classes, namely water bodies, forest, cultivated tree, settlement and paddy field. The result shows that area of cultivation tree and paddy fields are larger than others in midstream, and settlement is denser in downstream, particularly at riparian landscapes. The LUCC into paddy field often occur at two period 1995 to 2005 and 2005 to 2015 with several area are 530.92 ha and 388.17 ha. The Qscs method calculation result for 1995 until 2015 was affected by land use cover composition in each year and it was defined by Curve Number (CN). High rainfall in 1995 was generating high run off potential volume. Nevertheless, curve number value was increase get near to 100, which indicate the potential of run off volume increases along with LUCC in each year, those are 70.95; 72.47; and 72.81.

  8. Rebuilding Mount St. Helens

    USGS Publications Warehouse

    Schilling, Steve P.; Ramsey, David W.; Messerich, James A.; Thompson, Ren A.

    2006-01-01

    On May 18, 1980, Mount St. Helens, Washington exploded in a spectacular and devastating eruption that shocked the world. The eruption, one of the most powerful in the history of the United States, removed 2.7 cubic kilometers of rock from the volcano's edifice, the bulk of which had been constructed by nearly 4,000 years of lava-dome-building eruptions. In seconds, the mountain's summit elevation was lowered from 2,950 meters to 2,549 meters, leaving a north-facing, horseshoe-shaped crater over 2 kilometers wide. Following the 1980 eruption, Mount St. Helens remained active. A large lava dome began episodically extruding in the center of the volcano's empty crater. This dome-building eruption lasted until 1986 and added about 80 million cubic meters of rock to the volcano. During the two decades following the May 18, 1980 eruption, Crater Glacier formed tongues of ice around the east and west sides of the lava dome in the deeply shaded niche between the lava dome and the south crater wall. Long the most active volcano in the Cascade Range with a complex 300,000-year history, Mount St. Helens erupted again in the fall of 2004 as a new period of dome building began within the 1980 crater. Between October 2004 and February 2006, about 80 million cubic meters of dacite lava erupted immediately south of the 1980-86 lava dome. The erupting lava separated the glacier into two parts, first squeezing the east arm of the glacier against the east crater wall and then causing equally spectacular crevassing and broad uplift of the glacier's west arm. Vertical aerial photographs document dome growth and glacier deformation. These photographs enabled photogrammetric construction of a series of high-resolution digital elevation models (DEMs) showing changes from October 4, 2004 to February 9, 2006. From the DEMs, Geographic Information Systems (GIS) applications were used to estimate extruded volumes and growth rates of the new lava dome. The DEMs were also used to quantify dome

  9. Simulation studies of the physical and chemical processes occurring in the stratospheric clouds of the Mount St. Helens eruptions of May and June 1980

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Toon, O. B.; Whitten, C.; Keesee, R. G.; Hamill, P.

    1982-01-01

    The large and diverse set of observational data collected in the high-altitude clouds of May 18, May 25, and June 13, 1980 was organized and analyzed for trends which reveal the processes at work. The data were used to guide and constrain model simulations of the volcanic eruptions. A comprehensive one-dimensional model of stratospheric sulfate aerosols, sulfur precursor gases, and volcanic ash and dust particles is utilized which accounts for homogeneous and heterogeneous chemistry in the clouds, aerosol nucleation and growth, and cloud expansion. Computational results are given for the time histories of the gaseous species concentrations, sulfate aerosol size dispersions, and ash burdens in the eruption clouds. The long-term buildup of stratospheric aerosols in the Northern Hemisphere and the persistent effects of injected chlorine and water vapor on ozone are discussed. It is concluded that SO2, water vapor, and ash are the most important substances injected by the volcano into the stratosphere, with respect to both the widespread effects on composition and the impact on climate. It is found that the volcano probably had little influence on the climate ( 0.05 K global surface cooling) or on stratospheric ozone ( 0.2 percent maximum hemispherical reduction).

  10. Extrusion rate of the Mount St. Helens lava dome estimated from terrestrial imagery, November 2004-December 2005: Chapter 12 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Major, Jon J.; Kingsbury, Cole G.; Poland, Michael P.; LaHusen, Richard G.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Oblique, terrestrial imagery from a single, fixed-position camera was used to estimate linear extrusion rates during sustained exogenous growth of the Mount St. Helens lava dome from November 2004 through December 2005. During that 14-month period, extrusion rates declined logarithmically from about 8-10 m/d to about 2 m/d. The overall ebbing of effusive output was punctuated, however, by episodes of fluctuating extrusion rates that varied on scales of days to weeks. The overall decline of effusive output and finer scale rate fluctuations correlated approximately with trends in seismicity and deformation. Those correlations portray an extrusion that underwent episodic, broad-scale stick-slip behavior superposed on the finer scale, smaller magnitude stick-slip behavior that has been hypothesized by other researchers to correlate with repetitive, nearly periodic shallow earthquakes.

  11. Chemistry, mineralogy, and petrology of amphibole in Mount St. Helens 2004-2006 dacite: Chapter 32 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Thornber, Carl R.; Pallister, John S.; Lowers, Heather; Rowe, Michael C.; Mandeville, Charles W.; Meeker, Gregory P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Decompression-related reaction rims around subhedral, rounded, resorbed, and fragmented amphibole phenocrysts, regardless of composition, indicate that this mixed-crystal assemblage was being broken, abraded, and dissolved in the magma as a result of mechanical mixing before and during early stages of ascent from conduit roots extending into a mushy cupola of the shallow reservoir. In the earliest lava samples (October 2004), amphiboles with <3-μm rims associated with a glassier matrix than later samples suggest a slightly faster ascent rate consistent with the relatively high eruptive flux of the earliest phases of dome extrusion. Reaction rim widths of ~5 μm on amphibole in all subsequently extruded lava result from a steady influx and upward transport of magma from 3.5-2.5-km to ~1-km depth at rates of ~600 to ~1,200 m/day, through a conduit less than 10 m in radius. Slower ascent rates inferred from volumetric-flux and matrixcrystallization parameters are explained by a widening of the conduit to greater than 60 m radius within 1 km of the surface.

  12. Growth of the 2004-2006 lava-dome complex at Mount St. Helens, Washington: Chapter 9 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Vallance, James W.; Schneider, David J.; Schilling, Steve P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The chief near-surface controls on spine extrusion during 2004-6 have been vent location, relict topographic surfaces from the 1980s, and spine remnants emplaced previously during the present eruption. In contrast, glacier ice has had minimal influence on spine growth. Ice as thick as 150 m has prevented formation of marginal angle-of-repose talus fans but has not provided sufficient resistance to stop spine growth or slow it appreciably. Spines initially emerged along a relict south-facing slope as steep as 40° on the 1980s dome. The open space of the moat between that dome and the crater walls permitted initial southward migration of recumbent spines. An initial spine impinged on the opposing slopes of the crater and stopped; in contrast, recumbent whaleback spines of phase 3 impinged on opposing walls of the crater at oblique angles and rotated eastward before breaking up. Once spine remnants occupied all available open space to the south, spines thrust over previous remnants. Finally, with south and east portions of the moat filled, spine growth proceeded westward. Although Crater Glacier had only a small influence on the growing spines, spine growth affected the glacier dramatically, initially dividing it into two arms and then bulldozing it hundreds of meters, first east and then west, and heaping it more than 100 m higher than its original altitude.

  13. Magmatic conditions and processes in the storage zone of the 2004-2006 Mount St. Helens dacite: Chapter 31 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Rutherford, Malcom J.; Devine, Joseph D.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    O2 values of NNO +1 log unit. Magnetite compositions suggest that the 2004-6 magma was formed by mingling of magmas less than 5-8 weeks before eruption and that the magma last equilibrated within this temperature range. The amphibole phenocryst zoning involves approximately equal amounts of a pressure-sensitive Al-Tschermak molecular substitution and a temperature-sensitive edenite substitution in one cycle of growth. Hydrothermal experiments done on the natural dacite show that crystallization of the Fe- and Al-rich amphibole end member requires pressures of 200-300 MPa at temperatures of 900°C, conditions approaching the upper temperature limit of amphibole stability. The dacitic magma crystallizes the An68 plagioclase when the pressure drops to 200 MPa at 900°C. The magma must cool at this depth to produce a complete An68-An40 plagioclase zone and a Mg-rich layer on the amphiboles before the magma is cycled back to a high pressure, when a new layer of Fe-rich amphibole is acquired. The amphibole crystallizing in the dacite experiments at less than 200 MPa is lower in aluminum than any compositions in the natural cyclically zoned phenocrysts. The outer rim on some 2004-6 amphibole phenocrysts appears to have formed in the 100-200 MPa range, as do some phenocrysts in the May 1980 dacite pumice. Plagioclase rims of An35 in the 2004-6 magmas indicate that phenocryst growth continued until the pressure decreased to 130 MPa and that ascent was slow until this depth. Magma then entered the conduit for a relatively rapid ascent to the surface as indicated by the very thin (less than 5 μm) decompression-induced rims on the amphibole phenocrysts.

  14. The ISA-MIP Historical Eruption SO2 Emissions Assessment (HErSEA): an intercomparison for interactive stratospheric aerosol models

    NASA Astrophysics Data System (ADS)

    Mann, Graham; Dhomse, Sandip; Sheng, Jianxiong; Mills, Mike

    2016-04-01

    Major historical volcanic eruptions have injected huge amounts of sulphur dioxide into the stratosphere with observations showing an enhancement of the stratospheric aerosol layer for several years (ASAP, 2006). Such long-lasting increases in stratospheric aerosol loading cool the Earth's surface by scattering incoming solar radiation and warm the stratosphere via absorption of near infra-red solar and long-wave terrestrial radiation with complex effects on climate (e.g. Robock, 2000). Two recent modelling studies of Mount Pinatubo (Dhomse et al., 2014; Sheng et al. 2015) have highlighted that observations suggest the sulphur loading of the volcanically enhanced stratospheric aerosol may have been considerably lower than suggested by measurements of the injected SO2. This poster describes a new model intercomparison activity "ISA-MIP" for interactive stratospheric aerosol models within the framework of the SPARC initiative on Stratospheric Sulphur and its Role in Climate (SSiRC). The new "Historical Eruption SO2 emissions Assessment" (HErSEA) will intercompare model simulations of the three largest volcanic perturbations to the stratosphere in the last 50 years, 1963 Mt Agung, 1982 El Chichon and 1991 Mt Pinatubo. The aim is to assess how effectively the emitted SO2 translates into perturbations to stratospheric aerosol properties and simulated radiative forcings in different composition-climate models with interactive stratospheric aerosol (ISA). Each modelling group will run a mini-ensemble of transient AMIP-type runs for the 3 eruptions with a control no-eruption run followed by upper and lower bound injection amount estimates and 3 different injection height settings for two shallow (e.g. 19-21km amd 23-25km) and one deep (e.g. 19-25km) injection. First order analysis will intercompare stratospheric aerosol metrics such as 2D-monthly AOD(550nm, 1020nm) and timeseries of tropical and NH/SH mid-visible extinction at three different models levels (15, 20 and 25km

  15. Mass-independent sulfur isotopic compositions in stratospheric volcanic eruptions.

    PubMed

    Baroni, Mélanie; Thiemens, Mark H; Delmas, Robert J; Savarino, Joël

    2007-01-05

    The observed mass-independent sulfur isotopic composition (Delta33S) of volcanic sulfate from the Agung (March 1963) and Pinatubo (June 1991) eruptions recorded in the Antarctic snow provides a mechanism for documenting stratospheric events. The sign of Delta33S changes over time from an initial positive component to a negative value. Delta33S is created during photochemical oxidation of sulfur dioxide to sulfuric acid on a monthly time scale, which indicates a fast process. The reproducibility of the results reveals that Delta33S is a reliable tracer to chemically identify atmospheric processes involved during stratospheric volcanism.

  16. Hazard information management during the autumn 2004 reawakening of Mount St. Helens volcano, Washington: Chapter 24 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Driedger, Carolyn L.; Neal, Christina A.; Knappenberger, Tom H.; Needham, Deborah H.; Harper, Robert B.; Steele, William P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    The 2004 reawakening of Mount St. Helens quickly caught the attention of government agencies as well as the international news media and the public. Immediate concerns focused on a repeat of the catastrophic landslide and blast event of May 18, 1980, which remains a vivid memory for many individuals. Within several days of the onset of accelerating seismicity, media inquiries increased exponentially. Personnel at the U.S. Geological Survey, the Pacific Northwest Seismic Network, and the Gifford Pinchot National Forest soon handled hundreds of press inquiries and held several press briefings per day. About one week into the event, a Joint Information Center was established to help maintain a consistent hazard message and to provide a centralized information source about volcanic activity, hazards, area closures, and media briefings. Scientists, public-affairs specialists, and personnel from emergency-management, health, public-safety, and land-management agencies answered phones, helped in press briefings and interviews, and managed media access to colleagues working on science and safety issues. For scientists, in addition to managing the cycle of daily fieldwork, challenges included (1) balancing accurate interpretations of data under crisis conditions with the need to share information quickly, (2) articulating uncertainties for a variety of volcanic scenarios, (3) minimizing scientific jargon, and (4) frequently updating and effectively distributing talking points. Success of hazard information management during a volcanic crisis depends largely on scientists’ clarity of communication and thorough preplanning among interagency partners. All parties must commit to after-action evaluation and improvement of communication plans, incorporating lessons learned during each event.

  17. Mount St. Helens Rebirth

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The catastrophic eruption of Mt. St. Helens 20 years ago today (on May 18, 1980), ranks among the most important natural events of the twentieth century in the United States. Because Mt. St. Helens is in a remote area of the Cascades Mountains, only a few people were killed by the eruption, but property damage and destruction totaled in the billions of dollars. Mount St. Helens is an example of a composite or stratovolcano. These are explosive volcanoes that are generally steep-sided, symmetrical cones built up by the accumulation of debris from previous eruptions and consist of alternating layers of lava flows, volcanic ash and cinder. Some of the most photographed mountains in the world are stratovolcanoes, including Mount Fuji in Japan, Mount Cotopaxi in Ecuador, Mount Hood in Oregon, and Mount Rainier in Washington. The recently erupting Mount Usu on the island of Hokkaido in Japan is also a stratovolcano. Stratovolcanoes are characterized by having plumbing systems that move magma from a chamber deep within the Earth's crust to vents at the surface. The height of Mt. St. Helens was reduced from about 2950 m (9677 ft) to about 2550 m (8364 ft) as a result of the explosive eruption on the morning of May 18. The eruption sent a column of dust and ash upwards more than 25 km into the atmosphere, and shock waves from the blast knocked down almost every tree within 10 km of the central crater. Massive avalanches and mudflows, generated by the near-instantaneous melting of deep snowpacks on the flanks of the mountain, devastated an area more than 20 km to the north and east of the former summit, and rivers choked with all sorts of debris were flooded more than 100 km away. The area of almost total destruction was about 600 sq. km. Ash from the eruption cloud was rapidly blown to the northeast and east producing lightning which started many small forest fires. An erie darkness caused by the cloud enveloped the landscape more than 200 km from the blast area, and ash

  18. Small volcanic eruptions and the stratospheric sulfate aerosol burden

    NASA Astrophysics Data System (ADS)

    Pyle, David M.

    2012-09-01

    Understanding of volcanic activity and its impacts on the atmosphere has evolved in discrete steps, associated with defining eruptions. The eruption of Krakatau, Indonesia, in August 1883 was the first whose global reach was recorded through observations of atmospheric phenomena around the world (Symons 1888). The rapid equatorial spread of Krakatau's ash cloud revealed new details of atmospheric circulation, while the vivid twilights and other optical phenomena were soon causally linked to the effects of particles and gases released from the volcano (e.g. Stothers 1996, Schroder 1999, Hamilton 2012). Later, eruptions of Agung, Bali (1963), El Chichón, Mexico (1982) and Pinatubo, Philippines (1991) led to a fuller understanding of how volcanic SO2 is transformed to a long-lived stratospheric sulfate aerosol, and its consequences (e.g. Meinel and Meinel 1967, Rampino and Self 1982, Hoffman and Rosen 1983, Bekki and Pyle 1994, McCormick et al 1995). While our ability to track the dispersal of volcanic emissions has been transformed since Pinatubo, with the launch of fleets of Earth-observing satellites (e.g. NASA's A-Train; ESA's MetOp) and burgeoning networks of ground-based remote-sensing instruments (e.g. lidar and sun-photometers; infrasound and lightning detection systems), there have been relatively few significant eruptions. Thus, there have been limited opportunities to test emerging hypotheses including, for example, the vexed question of the role of 'smaller' explosive eruptions in perturbations of the atmosphere—those that may just be large enough to reach the stratosphere (of size 'VEI 3', Newhall and Self 1982, Pyle 2000). Geological evidence, from ice-cores and historical eruptions, suggests that small explosive volcanic eruptions with the potential to transport material into the stratosphere should be frequent (5-10 per decade), and responsible for a significant proportion of the long-term time-averaged flux of volcanic sulfur into the stratosphere

  19. Monitoring Mount Baker Volcano

    USGS Publications Warehouse

    Malone, S.D.; Frank, D.

    1976-01-01

    Hisotrically active volcanoes in the conterminous United States are restricted to the Cascade Range and extend to the Cascade Range and extend from Mount Baker near the Canadian border to Lassen Peak in northern California. Since 1800 A.D, most eruptive activity has been on a relatively small scale and has not caused loss of life or significant property damage. However, future  volcanism predictably will have more serious effects because of greatly increased use of land near volcanoes during the present century. (See "Appraising Volcanic Hazards of the Cascade Range of the Northwestern United States," Earthquake Inf. Bull., Sept.-Oct. 1974.) The recognition an impending eruption is highly important in order to minimize the potential hazard to people and property. Thus, a substantial increase in hydrothermal activity at Mount Baker in March 1975 ( see "Mount Baker Heating Up," July-Aug. 1975 issue) was regarded as a possible first signal that an eruption might occur, and an intensive monitoring program was undertaken. 

  20. Lahars of Mount Pinatubo, Philippines

    USGS Publications Warehouse

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

    1997-01-01

    On June 15, 1991, Mount Pinatubo in the Philippines exploded in the second largest volcanic eruption on Earth this century. This eruption deposited more than 1 cubic mile (5 cubic kilometers) of volcanic ash and rock fragments on the volcano's slopes. Within hours, heavy rains began to wash this material down into the surrounding lowlands in giant, fast-moving mudflows called lahars. In the next four rainy seasons, lahars carried about half of the deposits off the volcano, causing even more destruction in the lowlands than the eruption itself.

  1. Mount St. Helens aerosol evolution

    NASA Technical Reports Server (NTRS)

    Oberbeck, V. R.; Farlow, N. H.; Fong, W.; Snetsinger, K. G.; Ferry, G. V.; Hayes, D. M.

    1982-01-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mount St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  2. Volcanic eruptions recorded in the Illimani ice core (Bolivia): 1918-1998 and Tambora periods

    NASA Astrophysics Data System (ADS)

    de Angelis, M.; Simões, J.; Bonnaveira, H.; Taupin, J.-D.; Delmas, R. J.

    2003-05-01

    Acid layers of volcanic origin detected in polar snow and ice layers are commonly used to document past volcanic activity on a global scale or, conversely, to date polar ice cores. Although most cataclysmic eruptions of the last two centuries (Pinatubo, El Chichon, Agung, Krakatoa, Cosiguina, Tambora, etc.) occurred in the tropics, cold tropical glaciers have not been used for the reconstruction of past volcanism. The glaciochemical study of a 137 m ice core drilled in 1999 close to the summit of Nevado Illimani (Eastern Bolivian Andes, 16°37' S, 67°46' W, 6350 m a.s.l.) demonstrates, for the first time, that such eruptions are recorded by both their tropospheric and stratospheric deposits. An 80-year ice sequence (1918-1998) and the Tambora years have been analyzed in detail. In several cases, ash, chloride and fluoride were also detected. The ice records of the Pinatubo (1991), Agung (1963) and Tambora (1815) eruptions are discussed in detail. Less important eruptions located in the Andes are also recorded and may also disturb background aerosol composition on a regional scale.

  3. Volcanic eruptions recorded in the Illimani ice core (Bolivia): 1918Â 1998 and Tambora periods

    NASA Astrophysics Data System (ADS)

    de Angelis, M.; Simões, J.; Bonnaveira, H.; Taupin, J.-D.; Delmas, R. J.

    2003-10-01

    Acid layers of volcanic origin detected in polar snow and ice layers are commonly used to document past volcanic activity on a global scale or, conversely, to date polar ice cores. Although most cataclysmic eruptions of the last two centuries (Pinatubo, El Chichon, Agung, Krakatoa, Cosiguina, Tambora, etc.) occurred in the tropics, cold tropical glaciers have not been used for the reconstruction of past volcanism. The glaciochemical study of a 137 m ice core drilled in 1999 close to the summit of Nevado Illimani (Eastern Bolivian Andes, 16°37' S, 67°46' W, 6350 m asl) demonstrates, for the first time, that such eruptions are recorded by both their tropospheric and stratospheric deposits. An 80-year ice sequence (1918-1998) and the Tambora years have been analyzed in detail. In several cases, ash, chloride and fluoride were also detected. The ice records of the Pinatubo (1991), Agung (1963) and Tambora (1815) eruptions are discussed in detail. The potential impact of less important regional eruptions is discussed.

  4. Mount Vesuvius: 2000 years of volcanological observations

    NASA Astrophysics Data System (ADS)

    Scandone, Roberto; Giacomelli, Lisetta; Gasparini, Paolo

    1993-11-01

    Mount Vesuvius had eruptions ranging between VEI 5+ to 0-1 during the last 2000 years. Infrequent explosive eruptions are recorded during the period 79 AD to 1631. Since the violent explosive eruption of 1631, the volcano has been in persistent activity, rebuilding the morphology that it had before that eruption. A succession of explosive and effusive eruptions occurred until 1944, with a predominance of short and violent episodes until 1872 and longer effusive eruptions since that date. Two factors mainly controlled the character of volcanic activity during this period: (1) the strength of the cone, which allowed, in the earlier period, an easy fracturing, rapid drainage, and pressure release of the magma column; (2) the interaction between magma and water, which enhanced the explosivity of several eruptions. The volcano appears to have reached a stage of quiescence because it finally attained a shape of equilibrium in which the height of the mountain is sufficient to counterbalance the buoyancy of the magma.

  5. Mount Vesuvius, Italy

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image of Mt. Vesuvius, Italy was acquired September 26, 2000. The full-size false-color image covers an area of 36 by 45 km. Vesuvius overlooks the city of Naples and the Bay of Naples in central Italy. (Popocatepetl and Mount Fuji are other volcanos surrounded by dense urban areas.) In 79 AD, Vesuvius erupted cataclysmically, burying all of the surrounding cites with up to 30 m of ash. The towns of Pompeii and Herculanaeum were rediscovered in the 18th century, and excavated in the 20th century. They provide a snapshot of Roman life from 2000 years ago: perfectly preserved are wooden objects, food items, and the casts of hundreds of victims. Vesuvius is intensively monitored for potential signs of unrest that could signal the beginning of another eruption. Image courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

  6. Directed blasts and blast-generated pyroclastic density currents: a comparison of the Bezymianny 1956, Mount St Helens 1980, and Soufrière Hills, Montserrat 1997 eruptions and deposits

    USGS Publications Warehouse

    Belousov, Alexander; Voight, Barry; Belousova, Marina

    2007-01-01

    We compare eruptive dynamics, effects and deposits of the Bezymianny 1956 (BZ), Mount St Helens 1980 (MSH), and Soufrière Hills volcano, Montserrat 1997 (SHV) eruptions, the key events of which included powerful directed blasts. Each blast subsequently generated a high-energy stratified pyroclastic density current (PDC) with a high speed at onset. The blasts were triggered by rapid unloading of an extruding or intruding shallow magma body (lava dome and/or cryptodome) of andesitic or dacitic composition. The unloading was caused by sector failures of the volcanic edifices, with respective volumes for BZ, MSH, and SHV c. 0.5, 2.5, and 0.05 km3 . The blasts devastated approximately elliptical areas, axial directions of which coincided with the directions of sector failures. We separate the transient directed blast phenomenon into three main parts, the burst phase, the collapse phase, and the PDC phase. In the burst phase the pressurized mixture is driven by initial kinetic energy and expands rapidly into the atmosphere, with much of the expansion having an initially lateral component. The erupted material fails to mix with sufficient air to form a buoyant column, but in the collapse phase, falls beyond the source as an inclined fountain, and thereafter generates a PDC moving parallel to the ground surface. It is possible for the burst phase to comprise an overpressured jet, which requires injection of momentum from an orifice; however some exploding sources may have different geometry and a jet is not necessarily formed. A major unresolved question is whether the preponderance of strong damage observed in the volcanic blasts should be attributed to shock waves within an overpressured jet, or alternatively to dynamic pressures and shocks within the energetic collapse and PDC phases. Internal shock structures related to unsteady flow and compressibility effects can occur in each phase. We withhold judgment about published shock models as a primary explanation for the

  7. Directed blasts and blast-generated pyroclastic density currents: a comparison of the Bezymianny 1956, Mount St Helens 1980, and Soufrière Hills, Montserrat 1997 eruptions and deposits

    NASA Astrophysics Data System (ADS)

    Belousov, Alexander; Voight, Barry; Belousova, Marina

    2007-06-01

    We compare eruptive dynamics, effects and deposits of the Bezymianny 1956 (BZ), Mount St Helens 1980 (MSH), and Soufrière Hills volcano, Montserrat 1997 (SHV) eruptions, the key events of which included powerful directed blasts. Each blast subsequently generated a high-energy stratified pyroclastic density current (PDC) with a high speed at onset. The blasts were triggered by rapid unloading of an extruding or intruding shallow magma body (lava dome and/or cryptodome) of andesitic or dacitic composition. The unloading was caused by sector failures of the volcanic edifices, with respective volumes for BZ, MSH, and SHV c. 0.5, 2.5, and 0.05 km3. The blasts devastated approximately elliptical areas, axial directions of which coincided with the directions of sector failures. We separate the transient directed blast phenomenon into three main parts, the burst phase, the collapse phase, and the PDC phase. In the burst phase the pressurized mixture is driven by initial kinetic energy and expands rapidly into the atmosphere, with much of the expansion having an initially lateral component. The erupted material fails to mix with sufficient air to form a buoyant column, but in the collapse phase, falls beyond the source as an inclined fountain, and thereafter generates a PDC moving parallel to the ground surface. It is possible for the burst phase to comprise an overpressured jet, which requires injection of momentum from an orifice; however some exploding sources may have different geometry and a jet is not necessarily formed. A major unresolved question is whether the preponderance of strong damage observed in the volcanic blasts should be attributed to shock waves within an overpressured jet, or alternatively to dynamic pressures and shocks within the energetic collapse and PDC phases. Internal shock structures related to unsteady flow and compressibility effects can occur in each phase. We withhold judgment about published shock models as a primary explanation for the

  8. Major Optical Depth Perturbations to the Stratosphere from Volcanic Eruptions: Stellar-Extinction Period, 1961-1978

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.; Hansen, James E. (Technical Monitor)

    2001-01-01

    A revised chronology of stratospheric aerosol extinction due to volcanic eruptions has been assembled for the period 1961-1978, which immediately precedes the era of dedicated satellite measurements. On the whole, the most accurate data consist of published observations of stellar extinction, supplemented in part by other kinds of observational data. The period covered encompasses the important eruptions of Agung (1963) and Fuego (1974), whose dust veils are discussed with respect to their transport, decay, and total mass. The effective (area-weighted mean) radii of the aerosols for both eruptions are found to be 0.3-0.4 microns. It is confirmed that, among known tropical eruptions, Agung's dust was unique for a low-latitude eruption in remaining almost entirely confined to the hemisphere of its production. A new table of homogeneous visual optical depth perturbations, listed by year and by hemisphere, is provided for the whole period 1881-1978, including the pyrheliometric period before 1961 that was investigated previously.

  9. The response of the Southern Annular Mode to volcanic eruptions (Invited)

    NASA Astrophysics Data System (ADS)

    Jones, J. M.; Fogt, R. L.

    2013-12-01

    A strengthening of the Northern Hemisphere mid-latitude westerly winds often occurs in winters following volcanic eruptions, and is frequently framed in terms of a positive response of the Northern Annular Mode. Until recently, model-based studies have found a positive response of the Southern Annular Mode (SAM) following volcanic eruptions: the most recent CMIP5 simulations do find a weakly significant negative response in austral autumn and winter. Reanalysis data also indicate in some cases a negative response. We show here, considering the eruptions of Agung, El Chichón and Pinatubo, that these negative SAM responses are also evident in SAM reconstructions, an instrumental SAM index, and station SLP anomalies, and that they are most consistent in austral summer, but also occur in winter, and are strongest for Agung. We suggest that a more negative heat flux due to the reduced temperature gradient between low and mid-latitudes following volcanic eruptions warms the stratosphere and first weakens the vortex in the stratosphere. In the summer following, the anomalies propagate from the stratosphere to the troposphere, leading to a weaker tropospheric jet and negative tropospheric SAM index. The negative SAM index in the troposphere remains as long as the stratosphere remains relatively warm or the heat flux into the stratosphere remains below average. While El Niño events coincident with all three eruptions contribute to the heat flux into the stratosphere in the first year, the persistence of the warm stratosphere / strong heat flux anomalies after the El Niño events (especially the Pinatubo eruption) suggest that El Niño enhances, but does not lead to, the negative SAM response seen after these eruptions.

  10. Mirror mount

    DOEpatents

    Humpal, H.H.

    1987-11-10

    A mirror mount is provided that allows free pitch, yaw and roll motion of the mirror while keeping the location of a point on the surface of the mirror fixed in the rest frame of reference of the mount. Yaw movement is provided by two yaw cylinders that are bearing mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell that is air bearing mounted to move between a clamp and an upper pedestal bearing. The centers of curvature of the spherical surfaces of the shell lie upon the point. Pitch motion and roll motion are separately and independently imparted to mirror by a pair of pitch paddles and a pair of roll paddles that are independently and separately moved by control rods driven by motors. 5 figs.

  11. Mirror mount

    DOEpatents

    Humpal, H.H.

    1986-03-21

    A mirror mount is provided that allows free pitch, yaw and roll motion of the mirror while keeping the location of a point on the surface of the mirror fixed in the rest frame of reference of the mount. Yaw movement is provided by two yaw cylinders that are bearing mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell that is air bearing mounted to move between a clamp and an upper pedestal bearing. The centers of curvature of the spherical surfaces of the shell lie upon the point. Pitch motion and roll motion are separately and independently imparted to mirror by a pair of pitch paddles and a pair of roll paddles that are independently and separately moved by control rods driven by motors.

  12. Mirror mount

    DOEpatents

    Humpal, Harold H.

    1987-01-01

    A mirror mount (10) is provided that allows free pitch, yaw and roll motion of the mirror (28) while keeping the location of a point (56) on the surface of the mirror (28) fixed in the rest frame of reference of the mount (10). Yaw movement is provided by two yaw cylinders (30,32) that are bearing (52) mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell (42) that is air bearing (72,74) mounted to move between a clamp (60) and an upper pedestal bearing (44). The centers of curvature of the spherical surfaces of the shell (42) lie upon the point (56). Pitch motion and roll motion are separately and independently imparted to mirror (28) by a pair of pitch paddles (34) and a pair of roll paddles (36) that are independently and separately moved by control rods (76,80) driven by motors (78,82).

  13. Creeping eruption

    MedlinePlus

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

  14. Jupiter Eruptions

    NASA Image and Video Library

    2008-01-25

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

  15. Reports from Science Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Pollack, James B.

    1981-01-01

    The following reports describe extensive measurements of the properties of the gases and aerosols (particles) in the volcanic clouds produced by the eruptions of Mount St. Helens from March through August 1980. Volcanic material was first injected into the atmosphere on 27 March 1980. This material, as well as that introduced by subsequent eruptions during the next 2 months, was confined to the troposphere. On 18 May the first of several major explosions occurred in which some of the volcanic cloud penetrated well into the stratosphere. The nature of the volcanic activity at Mount St. Helens from the end of March through June was described.

  16. Landsat observations of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Bohn, C. G.; Bly, B. G.

    1981-01-01

    The eruption of Mount St. Helens on May 18, 1980, and subsequent destruction of approximately 593 square kilometers (229 square miles) of vegetation, clearly provided a unique opportunity for earth-oriented satellite remote sensing systems. Landsat, a relatively high resolution Multispectral Scanner (MSS) system, imaged Mount St. Helens both before and after its major eruption. Digital data have been used to create a damage assessment map and a change detection image. Several classes of timber damage and land cover modification have been developed. Acreages for each class have been tabulated.

  17. Mirror mount

    DOEpatents

    Kuklo, Thomas C.; Bender, Donald A.

    1994-01-01

    A unique lens or mirror mount having adjustable constraints at two key locations to allow for "X" and "Y" tilts of the mirror only. The device uses two pair of flexures of a type such that the pivots of the mirror gimble are rigidly fixed in all planes allowing the device to have zero stacking tolerance and zero wear over time.

  18. Mount Rainier active cascade volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

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

  19. Eruptive Prominence

    NASA Image and Video Library

    2017-12-08

    Large, eruptive prominence in He II at 304Å, with an image of the Earth added for size comparison. This prominence from 24 July 1999 is particularly large and looping, extending over 35 Earths out from the Sun. Erupting prominences (when Earthward directed) can affect communications, navigation systems, even power grids, while also producing auroras visible in the night skies. Credit: NASA/GSFC/SOHO/ESA To learn more go to the SOHO website: sohowww.nascom.nasa.gov/home.html To learn more about NASA's Sun Earth Day go here: sunearthday.nasa.gov/2010/index.php

  20. 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.

  1. 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

  2. Mount St. Helens Flyover

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image of Mt. St. Helens volcano in Washington State was acquired on August 8, 2000 and covers an area of 37 by 51 km. Mount Saint Helens, a volcano in the Cascade Range of southwestern Washington that had been dormant since 1857, began to show signs of renewed activity in early 1980. On 18 May 1980, it erupted with such violence that the top of the mountain was blown off, spewing a cloud of ash and gases that rose to an altitude of 19 kilometers. The blast killed about 60 people and destroyed all life in an area of some 180 square kilometers (some 70 square miles), while a much larger area was covered with ash and debris. It continues to spit forth ash and steam intermittently. As a result of the eruption, the mountain's elevation decreased from 2,950 meters to 2,549 meters. The simulated fly-over was produced by draping ASTER visible and near infrared image data over a digital topography model, created from ASTER's 3-D stereo bands. The color was computer enhanced to create a 'natural' color image, where the vegetation appears green. The topography has been exaggerated 2 times to enhance the appearance of the relief. Landsat7 aquired an image of Mt. St. Helens on August 22, 1999. Image and animation courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  3. Mirror mount

    DOEpatents

    Kuklo, T.C.; Bender, D.A.

    1994-10-04

    A unique lens or mirror mount having adjustable constraints at two key locations to allow for ''X'' and ''Y'' tilts of the mirror only is disclosed. The device uses two pair of flexures of a type such that the pivots of the mirror gimble are rigidly fixed in all planes allowing the device to have zero stacking tolerance and zero wear over time. 4 figs.

  4. Volcano ecology: flourishing on the flanks of Mount St. Helens

    Treesearch

    Rhonda Mazza; Charlie Crisafulli

    2016-01-01

    Mount St. Helens’ explosive eruption on May 18, 1980, was a pivotal moment in the field of disturbance ecology. The subsequent sustained, integrated research effort has shaped the development of volcano ecology, an emerging field of focused research. Excessive heat, burial, and impact force are some of the disturbance mechanisms following an eruption. They are also...

  5. Mount st. Helens volcano: recent and future behavior.

    PubMed

    Crandell, D R; Mullineaux, D R; Rubin, M

    1975-02-07

    Mount St. Helens volcano in southern Washington has erupted many times during the last 4000 years, usually after brief dormant periods. This behavior pattern. suggests that the volcano, last active in 1857, will erupt again-perhaps within the next few decades. Potential volcanic hazards of several kinds should be considered in planning for land use near the volcano.

  6. 25 years of ecological change at Mount St. Helens.

    Treesearch

    V.H. Dale; C.M. Crisafulli; F.J. Swanson

    2005-01-01

    18 May 2005 marks the 25th anniversary of the massive eruption of Mount St. Helens. This eruption involved diverse geological processes (1) that disturbed forests, meadows, lakes, an drivers (2) (see the figure). A huge landslide and searing flows of hot gases and pumic framents (pyroclastic flows) inundated 60 km2 of land, obliterating...

  7. Deformation monitoring at Mount St. Helens in 1981 and 1982

    USGS Publications Warehouse

    Chadwick, W.W.; Swanson, D.A.; Iwatsubo, E.Y.; Heliker, C.C.; Leighley, T.A.

    1983-01-01

    For several weeks before each eruption of Mount St. Helens in 1981 and 1982, viscous magma rising in the feeder conduit inflated the lava dome and shoved the crater floor laterally against the immobile crater walls, producing ground cracks and thrust faults. The rates of deformation accelerated before eruptions, and thus it was possible to predict eruptions 3 to 19 days in advance. Lack of deformation outside the crater showed that intrusion of magma during 1981 and 1982 was not voluminous.

  8. Deformation monitoring at mount st. Helens in 1981 and 1982.

    PubMed

    Chadwick, W W; Swanson, D A; Iwatsubo, E Y; Heliker, C C; Leighley, T A

    1983-09-30

    For several weeks before each eruption of Mount St. Helens in 1981 and 1982, viscous magma rising in the feeder conduit inflated the lava dome and shoved the crater floor laterally against the immobile crater walls, producing ground cracks and thrust faults. The rates of deformation accelerated before eruptions, and thus it was possible to predict eruptions 3 to 19 days in advance. Lack of deformation outside the crater showed that intrusion of magma during 1981 and 1982 was not voluminous.

  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. Mounting structure

    NASA Technical Reports Server (NTRS)

    Ganssle, Eugene Robert (Inventor); Scott, Ralph Richard (Inventor); Williams, Richard Jean (Inventor)

    1978-01-01

    A mounting platform for heat producing instruments operated in a narrow equilibrium temperature range comprises a grid-like structure with relatively large openings therein. The instruments are secured to and thermally coupled with the grid surface facing the instruments. Excess heat from the instruments is selectively radiated to the ambient through openings in the grid, the grid surfaces at these openings exhibiting low thermal emissivity and adsorptivity. The remainder of the grid is maintained at the equilibrium temperature and is covered with a thermal insulating blanket. Thus, the entire system including the platform and instruments is maintained substantially isothermal, whereby the instruments remain in fixed physical relationship to one another.

  11. Making sense of Mount St. Helens

    Treesearch

    Steve. Nash

    2010-01-01

    The eruption of Mount St. Helens in 1980 resulted in "a grand experiment that you could never have gotten anybody to fund," says Forest Service ecologist Charles Crisafulli. "Everything's new. It's a new landform." Unlike most misbehaving volcanoes, this one provided an accessible laboratory right along the Interstate-5 corridor, with the...

  12. 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

  13. Volcanic fire and glacial ice: Mount Rogers National Recreation Area

    USGS Publications Warehouse

    ,; ,

    2007-01-01

    In addition to containing the highest point in Virginia (Mount Rogers, elevation 5,729 feet), the Mount Rogers National Recreation Area (NRA) of the Jefferson National Forest is a window on the history of ancient volcanic eruptions and glacial movement.

  14. Volcano hazards in the Mount Jefferson region, Oregon

    USGS Publications Warehouse

    Walder, Joseph S.; Gardner, Cynthia A.; Conrey, Richard M.; Fisher, Bruce J.; Schilling, Steven P.

    1999-01-01

    Mount Jefferson is a prominent feature of the landscape seen from highways east and west of the Cascades. Mount Jefferson (one of thirteen major volcanic centers in the Cascade Range) has erupted repeatedly for hundreds of thousands of years, with its last eruptive episode during the last major glaciation which culminated about 15,000 years ago. Geologic evidence shows that Mount Jefferson is capable of large explosive eruptions. The largest such eruption occurred between 35,000 and 100,000 years ago, and caused ash to fall as far away as the present-day town of Arco in southeast Idaho. Although there has not been an eruption at Mount Jefferson for some time, experience at explosive volcanoes elsewhere suggests that Mount Jefferson cannot be regarded as extinct. If Mount Jefferson erupts again, areas close to the eruptive vent will be severely affected, and even areas tens of kilometers (tens of miles) downstream along river valleys or hundreds of kilometers (hundreds of miles) downwind may be at risk. Numerous small volcanoes occupy the area between Mount Jefferson and Mount Hood to the north, and between Mount Jefferson and the Three Sisters region to the south. These small volcanoes tend not to pose the far-reaching hazards associated with Mount Jefferson, but are nonetheless locally important. A concern at Mount Jefferson, but not at the smaller volcanoes, is the possibility that small to- moderate sized landslides could occur even during periods of no volcanic activity. Such landslides may transform as they move into lahars (watery flows of rock, mud, and debris) that can inundate areas far downstream. The population at immediate risk in the Mount Jefferson region is small, but these residents as well as other people who visit the area for recreation and work purposes should be aware of the potential hazards. Probably the greatest concern in the Mount Jefferson region is the possibility that large lahars might enter reservoirs on either side of the volcano

  15. Historical evidence for a connection between volcanic eruptions and climate change

    NASA Technical Reports Server (NTRS)

    Rampino, Michael R.

    1991-01-01

    The times of historical volcanic aerosol clouds were compared with changes in atmospheric temperatures on regional, hemispheric, and global scales. These involve either a direct comparison of individual significant eruption years with temperature records, or a comparison of eruption years with composited temperature records for several years before and after chosen sets of eruptions. Some studies have challenged the connection between individual eruptions and climate change. Mass and Portman (1989) recently suggested that the volcanic signal was present, but smaller than previously thought. In a study designed to test the idea that eruptions could cause small changes in climate, Hansen and other (1978) chose one of the best monitored eruptions at the time, the 1963 eruption of Agung volcano on the island of Bali. Using a simple radiation-balance model, in which an aerosol cloud in the tropics was simulated, this basic pattern of temperature change in the tropics and subtropics was reproduced. There may be natural limits to the atmospheric effects of any volcanic eruption. Self-limiting physical and chemical effects in eruption clouds were proposed. Model results suggest that aerosol microphysical processes of condensation and coagulation produce larger aerosols as the SO2 injection rate is increased. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on regional temperatures where the effects of volcanic aerosol clouds can be amplified by perturbed atmospheric circulation patterns, especially changes in mid-latitudes where meridional circulation patterns may develop. Such climatic perturbations can be detected in proxy evidence such as decreases in tree-ring widths and frost damage rings in climatically sensitive parts of the world, changes in treelines, weather anomalies such as unusually cold summers, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures.

  16. Arching Eruption

    NASA Image and Video Library

    2015-06-30

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

  17. 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.

  18. 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

  19. Solar radiation climate change over southern Africa and an assessment of the radiative impact of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Power, H. C.; Mills, D. M.

    2005-03-01

    Spatial and temporal variability in global, diffuse, and horizontal direct irradiance and sunshine duration has been evaluated at eight stations in South Africa and two stations in Namibia where the time series range between 21 and 41 years. Global and direct irradiance and sunshine duration decrease from northwest to southeast; diffuse irradiance increases toward the east. Annually averaged global irradiance Ga decreased between 1.3% (2.8 W m-2) and 1.7% (4.4 W m-2) per decade at Bloemfontein, Cape Town, Durban, Pretoria, and Upington. Annually averaged diffuse irradiance Da decreased 5.2% (3.0 W m-2) per decade at Grootfontein and 4.2% (3.1 W m-2) per decade at Port Elizabeth. Annual direct irradiance Ba decreased 2.1% (3.5 W m-2) per decade at Cape Town and 2.8% (5.7 W m-2) per decade at Alexander Bay. A simultaneous decrease in annually averaged daily sunshine duration Sa may have contributed to the decrease in Ba at Alexander Bay and the decrease in Ga at Pretoria. Increases in aerosols may have contributed to the observed decrease in Ga at Cape Town and Durban, and the decrease in Da at Grootfontein may be due to a decrease in aerosols. On average, variability in Sa explains 89.0%, 50.4%, and 89.5% of the variance in Ga, Da, and Ba respectively. The radiative response to changes in sunshine duration is greater for direct irradiance than for global and diffuse. In the 2 years following the 1963 Mount Agung eruption in Indonesia, changes in global irradiance over southern Africa were small and inconsistent. At eight stations, diffuse irradiance increased 21.9% (13.3 W m-2) on average and direct irradiance decreased 8.7% (15.5 W m-2). After the 1982 El Chichón eruption in Mexico, global irradiance

  20. Mount Pinatubo aerosols, chlorofluorocarbons, and ozone depletion

    SciTech Connect

    Brasseur, G.; Granier, C.

    1992-08-28

    The injection into the stratosphere of large quantities of sulfur during the June 1991 eruption of Mount Pinatube (Philippines) and the subsequent formation of sulfate aerosol particles have generated a number of perturbations in the atmosphere with potential effects on the Earth's climate. Changes in the solar and infrared radiation budget caused by the eruption should produce a cooling of the troposphere and a warming of the lower stratosphere. These changes could affect atmospheric circulation. In addition, heterogeneous chemical reactions on the surface of sulfate aerosol particles render the ozone molecules more vulnerable to atmospheric chlorine and hence to man-mademore » chlorofluorocarbons.« less

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

    USGS Publications Warehouse

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

    1999-01-01

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

  2. Mount St. Helens: A 30-year legacy of volcanism

    USGS Publications Warehouse

    Vallance, James W.; Gardner, Cynthia A.; Scott, William E.; Iverson, Richard M.; Pierson, Thomas C.

    2010-01-01

    The spectacular eruption of Mount St. Helens on 18 May 1980 electrified scientists and the public. Photodocumentation of the colossal landslide, directed blast, and ensuing eruption column—which reached as high as 25 kilometers in altitude and lasted for nearly 9 hours—made news worldwide. Reconnaissance of the devastation spurred efforts to understand the power and awe of those moments (Figure 1). The eruption remains a seminal historical event—studying it and its aftermath revolutionized the way scientists approach the field of volcanology. Not only was the eruption spectacular, but also it occurred in daytime, at an accessible volcano, in a country with the resources to transform disaster into scientific opportunity, amid a transformation in digital technology. Lives lost and the impact of the eruption on people and infrastructure downstream and downwind made it imperative for scientists to investigate events and work with communities to lessen losses from future eruptions.

  3. Preliminary volcano-hazard assessment for Mount Spurr Volcano, Alaska

    USGS Publications Warehouse

    Waythomas, Christopher F.; Nye, Christopher J.

    2001-01-01

    Mount Spurr volcano is an ice- and snow-covered stratovolcano complex located in the north-central Cook Inlet region about 100 kilometers west of Anchorage, Alaska. Mount Spurr volcano consists of a breached stratovolcano, a lava dome at the summit of Mount Spurr, and Crater Peak vent, a small stratocone on the south flank of Mount Spurr volcano. Historical eruptions of Crater Peak occurred in 1953 and 1992. These eruptions were relatively small but explosive, and they dispersed volcanic ash over areas of interior, south-central, and southeastern Alaska. Individual ash clouds produced by the 1992 eruption drifted east, north, and south. Within a few days of the eruption, the south-moving ash cloud was detected over the North Atlantic. Pyroclastic flows that descended the south flank of Crater Peak during both historical eruptions initiated volcanic-debris flows or lahars that formed temporary debris dams across the Chakachatna River, the principal drainage south of Crater Peak. Prehistoric eruptions of Crater Peak and Mount Spurr generated clouds of volcanic ash, pyroclastic flows, and lahars that extended to the volcano flanks and beyond. A flank collapse on the southeast side of Mount Spurr generated a large debris avalanche that flowed about 20 kilometers beyond the volcano into the Chakachatna River valley. The debris-avalanche deposit probably formed a large, temporary debris dam across the Chakachatna River. The distribution and thickness of volcanic-ash deposits from Mount Spurr volcano in the Cook Inlet region indicate that volcanic-ash clouds from most prehistoric eruptions were as voluminous as those produced by the 1953 and 1992 eruptions. Clouds of volcanic ash emitted from the active vent, Crater Peak, would be a major hazard to all aircraft using Ted Stevens Anchorage International Airport and other local airports and, depending on wind direction, could drift a considerable distance beyond the volcano. Ash fall from future eruptions could disrupt many

  4. Mount St. Helens and Kilauea volcanoes

    SciTech Connect

    Barrat, J.

    1989-01-01

    Mount St. Helens' eruption has taught geologists invaluable lessons about how volcanoes work. Such information will be crucial in saving lives and property when other dormant volcanoes in the northwestern United States--and around the world--reawaken, as geologists predict they someday will. Since 1912, scientists at the U.S. Geological Survey's Hawaiian Volcano Observatory have pioneered the study of volcanoes through work on Mauna Loa and Kilauea volcanoes on the island of Hawaii. In Vancouver, Wash., scientists at the Survey's Cascades Volcano Observatory are studying the after-effects of Mount St. Helens' catalysmic eruption as well as monitoring a number of other now-dormantmore » volcanoes in the western United States. This paper briefly reviews the similarities and differences between the Hawaiian and Washington volcanoes and what these volcanoes are teaching the volcanologists.« less

  5. Ocean Response to Volcanic Eruptions in CMIP5 Coupled Simulations

    NASA Astrophysics Data System (ADS)

    Ding, Yanni; Carton, James; Chepurin, Gennady; Stenchikov, Georgiy; Robock, Alan; Sentman, Lori; Krasting, John

    2014-05-01

    Questions regarding the ocean response to changes in atmospheric aerosol loading have arisen in several contexts recent years. Here we exploit the availability of new simulations produced as part of CMIP5 to revisit the ocean response to the five largest tropical volcanoes of the last 135 years (Krakatau, Santa Maria, Agung, El Chichón, and Pinatubo) in a set of 36 historical climate simulations produced using eight widely used climate models. All models show an annual average reduction in net surface solar radiation of 1-5 W m-2, a drop in net surface heat flux of 1-3 W m-2, and a resulting decline in SST of 0.1-0.3 K. Sea ice extent and mass also increase by about 5%. For smaller eruptions SST may recover in a few years, but our results confirm the suggestion of previous studies that the impacts on ocean heat content of major eruptions may persist for decades. The increase in sea ice area and mass also persists well beyond the lifetime of stratospheric aerosols due to the reinforcing impact of solar albedo feedback and reductions in thermodynamic surface heat loss. The cool SST signal also penetrates into the subsurface ocean, lowering 0-1000m temperature by an average of roughly 0.03 K, and persisting for many decades, masking some of the anthropogenic warming signal. Indeed, comparisons of simulations with and without volcanic aerosols show that the concentration of eruptions in the early years of the 20th century and again in the near the end of the century may mask some of the acceleration of ocean heating that might otherwise have been observed. A number of previous studies have explored the connection between volcanic eruptions and interannual to decadal climate variability with contradictory results. Here we combine the use of extensive numbers of ensemble members with a Rotated Extended Empirical Orthogonal Function analysis to further discriminate the natural and forced response, the result of which is no compelling evidence of a link between the timing

  6. In the wake of Mount St Helens.

    PubMed

    Nania, J; Bruya, T E

    1982-04-01

    On May 18, 1980, Mount St Helens, Washington State's most active volcano, erupted violently. Volcanic eruptions in recent geologic history have demonstrated tremendous environmental impact and caused significant loss of human life. Volcanic ash expelled during the eruption was deposited on much of eastern Washington and had a profound effect on local air quality. Although ash is relatively inert, analysis revealed a small but significant amount of free crystalline silica, the causative agent of silicosis. The fine particles of ash were of respirable size, and there was a remarkable increase in the volume of respiratory cases seen in emergency departments during the period of high airborne particulate levels. Numerous cases of injury indirectly related to the fall of ash were also seen. The long-term effect of exposure to this volcanic ash is unknown. A prompt, coordinated community medical response is necessary to protect the general population from the potential hazard of exposure to volcanic ash.

  7. Lidar measurements of Mount St. Helens effluents

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.

    1982-01-01

    Lidar measurements of the worldwide movement of stratospheric aerosols produced by the 18 May 1980 eruption of Mount St. Helens are described. Ground-based and airborne measurements show that the layers below 20 km produced by this eruption moved in an easterly direction while those above 20 km moved in a westerly direction. The effluent at jet stream altitudes of 10 to 12 km circled the globe in about 16 days and the effluent at 23 km (the highest altitude recorded) circled the globe in about 56 days. Mass calculations, using backscatter-to-mass conversion models, indicate that approximately half a million metric tons of new stratospheric material were produced by this eruption. Even though this represents a 200% increase in Northern Hemispheric aerosol, no significant long-term atmospheric temperature change should occur.

  8. 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.

  9. Mount St. Helens

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image of Mount St. Helens was captured one week after the March 8, 2005, ash and steam eruption, the latest activity since the volcano's reawakening in September 2004. The new lava dome in the southeast part of the crater is clearly visible, highlighted by red areas where ASTER's infrared channels detected hot spots from incandescent lava. The new lava dome is 155 meters (500 feet) higher than the old lava dome, and still growing.

    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 satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 21.9 by 24.4 kilometers (13.6 by 15.1 miles) Location: 46.2 degrees North latitude, 122.2 degrees West longitude Orientation: North at top Image Data: ASTER bands 8, 3, and 1 Original Data Resolution

  10. 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.

  11. Geochemical precursors to volcanic activity at Mount St. Helens, USA.

    PubMed

    Berlo, Kim; Blundy, Jon; Turner, Simon; Cashman, Kathy; Hawkesworth, Chris; Black, Stuart

    2004-11-12

    The importance of the interplay between degassing and crystallization before and after the eruption of Mount St. Helens (Washington, USA) in 1980 is well established. Here, we show that degassing occurred over a period of decades to days before eruptions and that the manner of degassing, as deduced from geochemical signatures within the magma, was characteristic of the eruptive style. Trace element (lithium) and short-lived radioactive isotope (lead-210 and radium-226) data show that ascending magma stalled within the conduit, leading to the accumulation of volatiles and the formation of lead-210 excesses, which signals the presence of degassing magma at depth.

  12. PV module mounting method and mounting assembly

    DOEpatents

    Lenox, Carl J.S.; Johnson, Kurt M.

    2013-04-23

    A method for mounting PV modules to a deck includes selecting PV module layout pattern so that adjacent PV module edges are spaced apart. PV mounting and support assemblies are secured to the deck according to the layout pattern using fasteners extending into the deck. The PV modules are placed on the PV mounting and support assemblies. Retaining elements are located over and secured against the upper peripheral edge surfaces of the PV modules so to secure them to the deck with the peripheral edges of the PV modules spaced apart from the deck. In some examples a PV module mounting assembly, for use on a shingled deck, comprises flashing, a base mountable on the flashing, a deck-penetrating fastener engageable with the base and securable to the deck so to secure the flashing and the base to the shingled deck, and PV module mounting hardware securable to the base.

  13. An erupted compound odontoma

    PubMed Central

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

    2014-01-01

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

  14. 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.

  15. Aspheric lens mounting

    NASA Astrophysics Data System (ADS)

    Lamontagne, Frédéric; Fuchs, Ulrike; Trabert, Martin; Möhl, Anna

    2017-11-01

    Mounting aspheres is often challenging because of the higher sensitivity to decenter and tilt compared to spherical lenses. This paper first describes aspheric surface decenter and tilt error as per ISO 10110 standard. Then, the most common lens mounting and alignment method for aspheric lenses are discussed in detail. Finally, an innovative mounting method that uses surface contact mounting is presented. This auto-centering method uses the optical surfaces as mounting interfaces to provide a high level of centering accuracy for aspheric lenses. Centering measurement results for different aspheric lenses mounted using this method are also presented.

  16. Magnetic core mounting system

    DOEpatents

    Ronning, Jeffrey J.

    2002-01-01

    A mounting apparatus for an electromagnetic device such as a transformer of inductor includes a generally planar metallic plate as a first heat sink, and a metallic mounting cup as a second heat sink. The mounting cup includes a cavity configured to receive the electromagnetic device, the cavity being defined by a base, and an axially-extending annular sidewall extending from the base to a flange portion of the mounting cup. The mounting cup includes first and second passages for allowing the leads of first and second windings of the electromagnetic device to be routed out of the cavity. The cavity is filled with a polyurethane potting resin, and the mounting cup, including the potted electromagnetic device, is mounted to the plate heat sink using fasteners. The mounting cup, which surrounds the electromagnetic device, in combination with the potting resin provides improved thermal transfer to the plate heat sink, as well as providing resistance to vibration and shocks.

  17. 'Taming Violently Erupting Volcanoes;' Volcanoes which Erupt Violently, need to be Tamed to Reduce their Destructive Capabilities

    NASA Astrophysics Data System (ADS)

    Cimorelli, S. A.

    2014-12-01

    After witnessing the deadly forces of volcanic eruptions as occurred from Mount Saint Helen in the U.S. and Mount Eyjofjallajokull in Iceland, which can cause so much death and destruction, it became obvious that, 'If we could reduce the forces involved we could reduce the catastrophic results significantly.' Typically, most of the volcanoes in Hawaii do not erupt as violently because they seem to be erupting and flowing on a somewhat regularly continuous basis or schedule. Our paper is suggesting a method, or many methods, by which the pressure buildup will be limited to substantially lower levels, than those which occur at present, by various procedures, before the actual eruption. We are suggesting that when we tame the highly destructive volcanoes' eruptions, we can reduce the effects which can ground more than a 100,000 flights; as occurred by Mount Eyjofjallajokull, back in 2010. It is critically important to be able to sense, measure, record and analyze the various conditions leading to the volcanic eruption.

  18. Discovery of the Largest Historic Silicic Submarine Eruption

    NASA Astrophysics Data System (ADS)

    Carey, Rebecca J.; Wysoczanski, Richard; Wunderman, Richard; Jutzeler, Martin

    2014-05-01

    It was likely twice the size of the renowned Mount St. Helens eruption of 1980 and perhaps more than 10 times bigger than the more recent 2010 Eyjafjallajökull eruption in Iceland. However, unlike those two events, which dominated world news headlines, in 2012 the daylong submarine silicic eruption at Havre volcano in the Kermadec Arc, New Zealand (Figure 1a; ~800 kilometers north of Auckland, New Zealand), passed without fanfare. In fact, for a while no one even knew it had occurred.

  19. Lessons from a major eruption: Mt. Pinatubo, Philippines

    NASA Astrophysics Data System (ADS)

    Pinatubo Volcano Observatory Team

    Small phreatic explosions on April 2, 1991, ended more than 400 years of quiescence at Mount Pinatubo. A joint Philippine-United States team worked quickly to understand the unrest and the eruptive history of Pinatubo, and to warn those at risk. These warnings led to the evacuation of at least 58,000 people prior to the volcano's climactic eruption on June 15. Although 320 people died in that eruption, mostly due to collapse of ash-covered roofs, the evacuations and other precautions averted a much greater loss of life and property.

  20. Fixed mount wavefront sensor

    DOEpatents

    Neal, Daniel R.

    2000-01-01

    A rigid mount and method of mounting for a wavefront sensor. A wavefront dissector, such as a lenslet array, is rigidly mounted at a fixed distance relative to an imager, such as a CCD camera, without need for a relay imaging lens therebetween.

  1. Platyrrhine dental eruption sequences.

    PubMed

    Henderson, Emily

    2007-10-01

    To determine dental eruption sequences of extant platyrrhines, 367 mandibles and maxillae of informative juvenile specimens from all 16 genera were scored for presence of permanent teeth including three intermediate eruption stages following Harvati (Am J Phys Anthropol 112 (2000) 69-85). The timing of molar eruption relative to that of the anterior dentition is variable in platyrrhines. Aotus is precocious, with all molars erupting in succession before replacement of any deciduous teeth, while Cebus is delayed in M2-3 eruption relative to I1-2. Callitrichines have a distinct tendency toward delayed canine and premolar development. Platyrrhine eruption sequences presented here show some evidence of conformity to Schultz's Rule, with relatively early replacement of deciduous dentition in "slower"-growing animals. The relationship of dental eruption sequences to degree of folivory, body mass, brain mass, and dietary quality is also examined. The early eruption of molars relative to anterior teeth in Pithecia, Chiropotes, and Cacajao, in comparison to genera such as Ateles, Lagothrix, and Alouatta, showing relatively later eruption of the molars, appears to be consistent with current phylogenetic hypotheses. Schultz (Am J Phys Anthropol 19 (1935) 489-581) postulated early relative molar eruption as the primitive dental eruption schedule for primates. The extremely early molar eruption of Aotus versus Callicebus (where both incisors erupt before M2 and M3, with M3 usually last) may lend support to the status of Aotus as a basal taxon. The early relative molar eruption of the fossil platyrrhine species Branisella boliviana is also consistent with this hypothesis (Takai et al.: Am J Phys Anthropol 111 (2000) 263-281). (c) 2007 Wiley-Liss, Inc.

  2. Volcanic hazards at Mount Rainier, Washington

    USGS Publications Warehouse

    Crandell, Dwight Raymond; Mullineaux, Donal Ray

    1967-01-01

    Mount Rainier is a large stratovolcano of andesitic rock in the Cascade Range of western Washington. Although the volcano as it now stands was almost completely formed before the last major glaciation, geologic formations record a variety of events that have occurred at the volcano in postglacial time. Repetition of some of these events today without warning would result in property damage and loss of life on a catastrophic scale. It is appropriate, therefore, to examine the extent, frequency, and apparent origin of these phenomena and to attempt to predict the effects on man of similar events in the future. The present report was prompted by a contrast that we noted during a study of surficial geologic deposits in Mount Rainier National Park, between the present tranquil landscape adjacent to the volcano and the violent events that shaped parts of that same landscape in the recent past. Natural catastrophes that have geologic causes - such as eruptions, landslides, earthquakes, and floods - all too often are disastrous primarily because man has not understood and made allowance for the geologic environment he occupies. Assessment of the potential hazards of a volcanic environment is especially difficult, for prediction of the time and kind of volcanic activity is still an imperfect art, even at active volcanoes whose behavior has been closely observed for many years. Qualified predictions, however, can be used to plan ways in which hazards to life and property can be minimized. The prediction of eruptions is handicapped because volcanism results from conditions far beneath the surface of the earth, where the causative factors cannot be seen and, for the most part, cannot be measured. Consequently, long-range predictions at Mount Rainier can be based only on the past behavior of the volcano, as revealed by study of the deposits that resulted from previous eruptions. Predictions of this sort, of course, cannot be specific as to time and locale of future events, and

  3. 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.

  4. Post Eruption Hydrology and Hydraulics of Mount Pinatubo, The Philippines

    DTIC Science & Technology

    1994-05-01

    and lower areas on the mountain supported a variety of crops including sugar cane, cassava , and maize. Much of the low-lying region surrounding the...rainfall frequency data as computed from the raw data and also after multiplication by factors to convert from observational day data to n-hour SU.S...rainfall of a given frequency can reasonably be estimated as a constant multiple of same- frequency average coastal rainfall. A constant multiplier equal to

  5. Mount St. Helens 30 years later: a landscape reconfigured.

    Treesearch

    Rhonda Mazza

    2010-01-01

    On May 18, 1980, after two months of tremors, Mount St. Helens erupted spectacularly and profoundly changed a vast area surrounding the volcano. The north slope of the mountain catastrophically failed, forming the largest landslide witnessed in modern times. The largest lobe of this debris avalanche raced 14 miles down the Toutle River...

  6. Forest development following mudflow deposition, Mount St. Helens, Washington

    Treesearch

    Marc H. Weber; Keith S. Hadley; Peter M. Frenzen; Jerry F. Franklin

    2006-01-01

    Volcanic mudflows are locally important disturbance agents in the Pacific Northwest rarely studied within the context of forest succession. We describe 18 years (1981–1999) of forest development on the Muddy River mudflow deposit following the 1980 eruption of Mount St. Helens using permanent plot data collected along two transects traversing the Cedar Flats river...

  7. Learning from Mount St. Helens: Catastrophic Events as Educational Opportunities.

    ERIC Educational Resources Information Center

    Anderson, Jeremy

    1987-01-01

    Maintains that the study of catastrophic events should be given temporary precedence over the normal curriculum in order to help students understand the causes, consequences, and recovery alternatives, deal with trauma, and allay fear of recurrence and feelings of helplessness. Uses the May 1980 eruption of Mount St. Helens to demonstrate how…

  8. Photovoltaic module mounting system

    DOEpatents

    Miros, Robert H. J.; Mittan, Margaret Birmingham; Seery, Martin N; Holland, Rodney H

    2012-09-18

    A solar array mounting system having unique installation, load distribution, and grounding features, and which is adaptable for mounting solar panels having no external frame. The solar array mounting system includes flexible, pedestal-style feet and structural links connected in a grid formation on the mounting surface. The photovoltaic modules are secured in place via the use of attachment clamps that grip the edge of the typically glass substrate. The panel mounting clamps are then held in place by tilt brackets and/or mid-link brackets that provide fixation for the clamps and align the solar panels at a tilt to the horizontal mounting surface. The tilt brackets are held in place atop the flexible feet and connected link members thus creating a complete mounting structure.

  9. Photovoltaic module mounting system

    DOEpatents

    Miros, Robert H. J. [Fairfax, CA; Mittan, Margaret Birmingham [Oakland, CA; Seery, Martin N [San Rafael, CA; Holland, Rodney H [Novato, CA

    2012-04-17

    A solar array mounting system having unique installation, load distribution, and grounding features, and which is adaptable for mounting solar panels having no external frame. The solar array mounting system includes flexible, pedestal-style feet and structural links connected in a grid formation on the mounting surface. The photovoltaic modules are secured in place via the use of attachment clamps that grip the edge of the typically glass substrate. The panel mounting clamps are then held in place by tilt brackets and/or mid-link brackets that provide fixation for the clamps and align the solar panels at a tilt to the horizontal mounting surface. The tilt brackets are held in place atop the flexible feet and connected link members thus creating a complete mounting structure.

  10. Effects of volcanism on the glaciers of Mount St. Helens

    USGS Publications Warehouse

    Brugman, Melinda M.; Post, Austin

    1981-01-01

    The cataclysmic eruption of Mount St. Helens May 18, 1980, removed 2.9 km2 (about 0.13 km3) of glacier snow and ice including a large part of Shoestring, Forsyth, Wishbone, Ape, Nelson, and all of Loowit and Leschi Glaciers. Minor eruptions and bulging of the volcano from March 27 to May 17 shattered glaciers which were on the deforming rock and deposited ash on other glaciers. Thick ash layers persisted after the May 18 eruption through the summer on most of the remaining snow and ice, and protected winter snow from melting on Swift and Dryer Glaciers. Melting and recrystalization of snow and ice surviving on Mount St. Helens could cause and lubricate mudflows and generate outburst floods. Study of glaciers that remain on this active volcano may assist in recognizing potential hazards on other volcanoes and lead to new contributions to knowledge of the transient response of glaciers to changes in mass balance or geometry.

  11. Small particles in plumes of Mount St. Helens

    NASA Technical Reports Server (NTRS)

    Rose, W. I.; Chuan, R. L.; Woods, D. C.

    1982-01-01

    Particles in the size range 0.1-25 microns were sampled by aircraft carrying a quartz crystal microcascade in the Mount St. Helens plume on three dates in August and September 1980. Two of the sampling dates represented 'typical' emissions of the volcano between plinian eruptions. One sampling flight was made 1-4 hours before the small plinian eruption of August 7, 1980 when the plume had become discontinuous and visibly darker. The plume sampled on August 7, before the eruption, contained mainly approximately 2-micron diameter silicic glass particles, fragments of the Mount St. Helens magma. The typical plumes sampled on September 22 and August 6 had much smaller concentrations of particles, trimodal size distributions with peaks at 10, 0.4, and 0.1 microns. The particles were largely nonsilicate and apparently represented Cu-Zn oxide (10 micron peak), Al sulfate, chloride, and oxide, and sulfuric acid (smallest size peak).

  12. Tooth eruption without roots.

    PubMed

    Wang, X-P

    2013-03-01

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

  13. Tooth Eruption without Roots

    PubMed Central

    2013-01-01

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

  14. 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.

  15. Deposits of large volcanic debris avalanches at Mount St. Helens and Mount Shasta volcanoes

    SciTech Connect

    Glicken, H.

    1985-01-01

    Large volcanic debris avalanches are among the world's largest mass movements. The rockslide-debris avalanche of the May 18, 1980, eruption of Mount St. Helens produced a 2.8 km/sup 3/ deposit and is the largest historic mass movement. A Pleistocene debris avalanche at Mount Shasta produced a 26 km/sup 3/ deposit that may be the largest Quaternary mass movement. The hummocky deposits at both volcanoes consist of rubble divided into (1) block facies that comprises unconsolidated pieces of the old edifice transported relatively intact, and (2) matrix facies that comprises a mixture of rocks from the old mountain and material pickedmore » up from the surrounding terrain. At Mount St. Helens, the juvenile dacite is found in the matrix facies, indicating that matrix facies formed from explosions of the erupting magma as well as from disaggregation and mixing of blocks. The block facies forms both hummocks and interhummock areas in the proximal part of the St. Helens avalanche deposit. At Mount St. Helens, the density of the old cone is 21% greater than the density of the avalanche deposit. Block size decreases with distance. Clast size, measured in the field and by sieving, coverages about a mean with distance, which suggests that blocks disaggregated and mixed together during transport.« less

  16. Renewed unrest at Mount Spurr Volcano, Alaska

    USGS Publications Warehouse

    Power, John A.

    2004-01-01

    The Alaska Volcano Observatory (AVO),a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys, has detected unrest at Mount Spurr volcano, located about 125 km west of Anchorage, Alaska, at the northeast end of the Aleutian volcanic arc.This activity consists of increased seismicity melting of the summit ice cap, and substantial rates of C02 and H2S emission.The current unrest is centered beneath the volcano's 3374-m-high summit, whose last known eruption was 5000–6000 years ago. Since then, Crater Peak, 2309 m in elevation and 4 km to the south, has been the active vent. Recent eruptions occurred in 1953 and 1992.

  17. Triggering of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Linde, Alan T.; Sacks, I. Selwyn

    1998-10-01

    Although earthquakes and volcanic eruptions are each manifestations of large-scale tectonic plate and mantle motions, it is usually thought that the occurrences of these events are not directly related. There have been some studies, however, in which triggering of volcanic eruptions by earthquakes (remote from the volcano) has been proposed,. The 1992 Landers (southern California) earthquake caused triggered seismicity at very large distances, including the magmatically active Long Valley caldera region which also experienced a significant coincident deformation transient. Motivated by this demonstration of the ability of a distant earthquake to disturb a volcanic system, and the earlier studies of specific cases of eruption triggering, we examine here the historical record of eruptions and earthquakes to see if there are indeed significantly more eruptions immediately following large earthquakes. We find that within a day or two of large earthquakes there are many more eruptions within a range of 750km than would otherwise be expected. Additionally, it is well known that volcanoes separated by hundreds of kilometres frequently erupt in unison; the characteristics of such eruption pairs are also consistent with the hypothesis that the second eruption is triggered by earthquakes associated with the first.

  18. Digital Data for Volcano Hazards in the Mount Jefferson Region, Oregon

    USGS Publications Warehouse

    Schilling, S.P.; Doelger, S.; Walder, J.S.; Gardner, C.A.; Conrey, R.M.; Fisher, B.J.

    2008-01-01

    Mount Jefferson has erupted repeatedly for hundreds of thousands of years, with its last eruptive episode during the last major glaciation which culminated about 15,000 years ago. Geologic evidence shows that Mount Jefferson is capable of large explosive eruptions. The largest such eruption occurred between 35,000 and 100,000 years ago. If Mount Jefferson erupts again, areas close to the eruptive vent will be severely affected, and even areas tens of kilometers (tens of miles) downstream along river valleys or hundreds of kilometers (hundreds of miles) downwind may be at risk. Numerous small volcanoes occupy the area between Mount Jefferson and Mount Hood to the north, and between Mount Jefferson and the Three Sisters region to the south. These small volcanoes tend not to pose the far-reaching hazards associated with Mount Jefferson, but are nonetheless locally important. A concern at Mount Jefferson, but not at the smaller volcanoes, is the possibility that small-to-moderate sized landslides could occur even during periods of no volcanic activity. Such landslides may transform as they move into lahars (watery flows of rock, mud, and debris) that can inundate areas far downstream. The geographic information system (GIS) volcano hazard data layer used to produce the Mount Jefferson volcano hazard map in USGS Open-File Report 99-24 (Walder and others, 1999) is included in this data set. Both proximal and distal hazard zones were delineated by scientists at the Cascades Volcano Observatory and depict various volcano hazard areas around the mountain.

  19. High bandwidth optical mount

    DOEpatents

    Bender, D.A.; Kuklo, T.

    1994-11-08

    An optical mount, which directs a laser beam to a point by controlling the position of a light-transmitting optic, is stiffened so that a lowest resonant frequency of the mount is approximately one kilohertz. The optical mount, which is cylindrically-shaped, positions the optic by individually moving a plurality of carriages which are positioned longitudinally within a sidewall of the mount. The optical mount is stiffened by allowing each carriage, which is attached to the optic, to move only in a direction which is substantially parallel to a center axis of the optic. The carriage is limited to an axial movement by flexures or linear bearings which connect the carriage to the mount. The carriage is moved by a piezoelectric transducer. By limiting the carriage to axial movement, the optic can be kinematically clamped to a carriage. 5 figs.

  20. Enhancements in biologically effective ultraviolet radiation following volcanic eruptions

    NASA Technical Reports Server (NTRS)

    Vogelmann, A. M.; Ackerman, T. P.; Turco, R. P.

    1992-01-01

    A radiative transfer model is used to estimate the changes in biologically effective radiation (UV-BE) at the earth's surface produced by the El Chichon (1982) and Mount Pinatubo (1991) eruptions. It is found that in both cases surface intensity can increase because the effect of ozone depletion outweighs the increased scattering.

  1. Intermediate magma genesis of Mount Hood and Mount Jefferson, OR: Insights from Cumulate Inclusions

    NASA Astrophysics Data System (ADS)

    Chen, N. M.; Kent, A. J.; Tepley, F. J., III

    2016-12-01

    The presence of cumulate plutonic inclusions in many volcanic systems provides constraints on the processes that occur within the magmatic plumbing system, and can provide insights not available from study of lavas alone. In petrographically complex intermediate magmas, cumulates may also provide samples of the parental magmas that contribute to intermediate magma genesis. Mount Hood and Mount Jefferson are two Cascade volcanoes that primarily erupt intermediate magmas, and are relatively understudied compared to nearby volcanoes. We present a comparative study of cumulate inclusions from these volcanoes using petrographic analysis combined with electron microprobe and laser ablation inductively coupled plasma mass spectrometry analysis of minerals from cumulate inclusions and host lava. Our goal is to further constrain the processes of intermediate magma genesis at these systems. Previous work at both Mount Hood and Mount Jefferson suggest that magma mixing is an important process in magma generation and evolution. At Mount Hood, where host andesites are produced by mixing between mafic and felsic parental magmas, the plagioclase from individual cumulate inclusions have a range of FeO and An contents that suggest both these parental magmas may form cumulate inclusions. Orthopyroxene compositions from cumulates also show a range of Mg# suggesting they derive from a range of parental magma compositions. At Mt. Jefferson, lavas from the most recent eruption contain cumulate inclusions that are similar in mineralogy and texture to Mount Hood cumulates. However, in contrast, plagioclases from both cumulate inclusions and host lavas have a range and pattern of MgO, FeO, and TiO2 versus An content that suggest the cumulates and host lavas originated from the same parental magma. These initial results indicate that although cumulate clots with similar mineralogy occur in lavas from both volcanoes, their chemistries indicate a different petrogenetic origin. The observed

  2. Mount St. Helens Volcano, WA, USA

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Mount St. Helens Volcano (46.0N, 122.0W) and its blast zone can be seen in this northeast looking infrared view. Mt. Rainier and Mt. Adams can also be seen in the near area. The Columbia River can be seen at the bottom of the view. When Mt. St. Helens erupted on 18 May 80, the top 1300 ft. disappeared within minutes. The blast area covered an area of more than 150 sq. miles and sent thousands of tons of ash into the upper atmosphere.

  3. Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon

    USGS Publications Warehouse

    Bacon, Charles R.

    2008-01-01

    Crater Lake partly fills one of the most spectacular calderas of the world, an 8-by-10-km basin more than 1 km deep formed by collapse of the volcano known as Mount Mazama (fig. 1) during a rapid series of explosive eruptions about 7,700 years ago. Having a maximum depth of 594 m, Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 km2 of pristine forested and alpine terrain, including the lake itself, virtually all of Mount Mazama, and most of the area of the geologic map. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama's climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, greatly enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. Lastly, the many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama are a source of information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive

  4. Stable mirror mount

    DOEpatents

    Cutburth, Ronald W.

    1990-01-01

    An improved mirror mount assembly is disclosed. The mirror mount assembly provides a post assembly slidable in a Y-axis orientation and a nut plate assembly slidable in an X-axis orientation and a device for simultaneously locking the post assembly and the key assembly in a fixed position.

  5. Stable mirror mount

    DOEpatents

    Cutburth, R.W.

    1983-11-04

    An improved mirror mount assembly is disclosed. The mirror mount assembly provides a post assembly slidable in a Y-axis orientation and a nut plate assembly slidable in an X-axis orientation and means for simultaneously locking said post assembly and said key assembly in a fixed position.

  6. Spherical mirror mount

    NASA Technical Reports Server (NTRS)

    Meyer, Jay L. (Inventor); Messick, Glenn C. (Inventor); Nardell, Carl A. (Inventor); Hendlin, Martin J. (Inventor)

    2011-01-01

    A spherical mounting assembly for mounting an optical element allows for rotational motion of an optical surface of the optical element only. In that regard, an optical surface of the optical element does not translate in any of the three perpendicular translational axes. More importantly, the assembly provides adjustment that may be independently controlled for each of the three mutually perpendicular rotational axes.

  7. Geology of the Ugashik-Mount Peulik Volcanic Center, Alaska

    USGS Publications Warehouse

    Miller, Thomas P.

    2004-01-01

    The Ugashik-Mount Peulik volcanic center, 550 km southwest of Anchorage on the Alaska Peninsula, consists of the late Quaternary 5-km-wide Ugashik caldera and the stratovolcano Mount Peulik built on the north flank of Ugashik. The center has been the site of explosive volcanism including a caldera-forming eruption and post-caldera dome-destructive activity. Mount Peulik has been formed entirely in Holocene time and erupted in 1814 and 1845. A large lava dome occupies the summit crater, which is breached to the west. A smaller dome is perched high on the southeast flank of the cone. Pyroclastic-flow deposits form aprons below both domes. One or more sector-collapse events occurred early in the formation of Mount Peulik volcano resulting in a large area of debris-avalanche deposits on the volcano's northwest flank. The Ugashik-Mount Peulik center is a calcalkaline suite of basalt, andesite, dacite, and rhyolite, ranging in SiO2 content from 51 to 72 percent. The Ugashik-Mount Peulik magmas appear to be co-genetic in a broad sense and their compositional variation has probably resulted from a combination of fractional crystallization and magma-mixing. The most likely scenario for a future eruption is that one or more of the summit domes on Mount Peulik are destroyed as new magma rises to the surface. Debris avalanches and pyroclastic flows may then move down the west and, less likely, east flanks of the volcano for distances of 10 km or more. A new lava dome or series of domes would be expected to form either during or within some few years after the explosive disruption of the previous dome. This cycle of dome disruption, pyroclastic flow generation, and new dome formation could be repeated several times in a single eruption. The volcano poses little direct threat to human population as the area is sparsely populated. The most serious hazard is the effect of airborne volcanic ash on aircraft since Mount Peulik sits astride heavily traveled air routes connecting the U

  8. Optoelectronic Mounting Structure

    DOEpatents

    Anderson, Gene R.; Armendariz, Marcelino G.; Baca, Johnny R. F.; Bryan, Robert P.; Carson, Richard F.; Chu, Dahwey; Duckett, III, Edwin B.; McCormick, Frederick B.; Peterson, David W.; Peterson, Gary D.; Reber, Cathleen A.; Reysen, Bill H.

    2004-10-05

    An optoelectronic mounting structure is provided that may be used in conjunction with an optical transmitter, receiver or transceiver module. The mounting structure may be a flexible printed circuit board. Thermal vias or heat pipes in the head region may transmit heat from the mounting structure to the heat spreader. The heat spreader may provide mechanical rigidity or stiffness to the heat region. In another embodiment, an electrical contact and ground plane may pass along a surface of the head region so as to provide an electrical contact path to the optoelectronic devices and limit electromagnetic interference. In yet another embodiment, a window may be formed in the head region of the mounting structure so as to provide access to the heat spreader. Optoelectronic devices may be adapted to the heat spreader in such a manner that the devices are accessible through the window in the mounting structure.

  9. 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.

  10. [Mechanisms of tooth eruption].

    PubMed

    Maltha, J C

    2014-04-01

    Tooth eruption is of the utmost importance for the normal development of the dentition and the face. Since the 1980s, it has been known that the tooth germ itself is not essential for facilitating the processes that make tooth eruption possible. For that reason, recent research on the regulatory mechanisms of tooth eruption has focused mainly on the enamel organ and the dental follicle. Different regulatory mechanisms act on the occlusal and the apical sides of an erupting tooth. On the occlusal side osteoclast differentiation is stimulated. This leads to the development of an eruption canal, a process in which macrophages and matrix metalloproteases also play an important role. On the apical side the most important factors are the transcription factor RUNX2 and the bone morphogenic protein 2. They are responsible for the deposition of trabecular bone in that area. Many regulatory mechanisms which are involved in tooth eruption are also active in other developmental processes. This explains that certain syndromes can also have an effect on the tooth eruption process.

  11. SYMPATHETIC SOLAR FILAMENT ERUPTIONS

    SciTech Connect

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

    2016-08-10

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

  12. 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.

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

    USGS Publications Warehouse

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

    2014-01-01

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

  14. Long-wave stratospheric transmission of Mount St. Helens ejecta

    NASA Technical Reports Server (NTRS)

    Kuhn, P. M.; Haughney, L. C.; Innis, R. C.

    1981-01-01

    The NASA/Ames Research C-141 aircraft underflew the Mount St. Helens ejecta plume in Utah three days after the eruption. Upward-looking 20-40-microns on-board radiometry provided data resulting in a calculated long-wave transmission of 0.93. From this value, an optical depth of 0.073 is inferred. This value is compared with an accepted background, stratospheric infrared optical depth of 0.06. Assumptions on particle size, shortwave albedo, and thermal warming imply little surface temperature change caused by the ejecta on the third day immediately following the eruption.

  15. Long-wave stratospheric transmission of Mount St. Helens ejecta.

    PubMed

    Kuhn, P M; Haughney, L C; Innis, R C

    1981-01-01

    The NASA/Ames Research C-141 aircraft underflew the Mount St. Helens ejecta plume in Utah three days after the eruption. Upward-looking 20-40-microm on-board radiometry provided data resulting in a calculated long-wave transmission of 0.93. From this value, an optical depth of 0.073 is inferred. This value is compared with an accepted background, stratospheric infrared optical depth of 0.06. Assumptions on particle size, shortwave albedo, and thermal warming imply little surface temperature change caused by the ejecta on the third day immediately following the eruption.

  16. An Erupted Silent Tumour.

    PubMed

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

    2016-07-01

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

  17. Identifying Successive Eruption of Guntur Volcanic Complex Using Magnetic Susceptibility and Polarimetric Synthetic Aperture Radar (PolSAR) Data

    NASA Astrophysics Data System (ADS)

    Saepuloh, Asep; Bakker, Erwin

    2017-06-01

    Identifying distribution and stratigraphic of volcanic products are important not only for mitigating volcanic hazards, but also to know the characteristics of the successive eruptions. Guntur volcanic complex located in Garut, West Java, Indonesia was selected as study area because of the last eruption took place in 1847 and the volcanic activity has been dormant since then, however its seismicity is still active. During the period of July to October 2009, the hypocentre distribution of volcano tectonic earthquakes is mostly located at western flank of the volcano, beneath Guntur - Gandapura craters at the depth of less than 5 km. This study is aimed to identify distribution and succession of volcanic products based on their magnetic properties and backscattering signal of Polarimetric Synthetic Aperture Radar (PolSAR) data. The polarimetric decomposition method was used to identify the distribution of the volcanic products based on their scattering characteristics. Then, the field measurement using SM-30 magnetic susceptibility meter was performed to confirm the units of volcanic products and interpret their successions. According to the polarimetric decomposition method, we could identify fifteen successive eruptions formed Guntur Volcano Complex and termed as Khuluk and Gumuk in Indonesian standard. The successions were produced Gumuk Windu, Gumuk Malang, Gumuk Pulus, Gumuk Putrri, Khuluk Meungpeuk, Gumuk Cakra, Gumuk Gandapura, Gumuk Putri, Gumuk Gajah, Gumuk Batususun, Khuluk Pasirlaku, Gumuk Agung, Gumuk Picung, Gumuk Pasirmalang, Gumuk Masigit, Khuluk Kabuyutan and Khuluk Guntur. The magnetic susceptibility confirmed that the variations of magnetic susceptibility of rocks at each gumuk agreed with their stratigraphy.

  18. Distribution of melt beneath Mount St Helens and Mount Adams inferred from magnetotelluric data

    USGS Publications Warehouse

    Hill, G.J.; Caldwell, T.G.; Heise, W.; Chertkoff, D.G.; Bibby, H.M.; Burgess, M.K.; Cull, J.P.; Cas, Ray A.F.

    2009-01-01

    Three prominent volcanoes that form part of the Cascade mountain range in Washington State (USA)Mounts StHelens, Adams and Rainierare located on the margins of a mid-crustal zone of high electrical conductivity1,5. Interconnected melt can increase the bulk conductivity of the region containing the melt6,7, which leads us to propose that the anomalous conductivity in this region is due to partial melt associated with the volcanism. Here we test this hypothesis by using magnetotelluric data recorded at a network of 85 locations in the area of the high-conductivity anomaly. Our data reveal that a localized zone of high conductivity beneath thisvolcano extends downwards to join the mid-crustal conductor. As our measurements were made during the recent period of lava extrusion at Mount St Helens, we infer that the conductivity anomaly associated with the localized zone, and by extension with the mid-crustal conductor, is caused by the presence of partial melt. Our interpretation is consistent with the crustal origin of silicic magmas erupting from Mount St Helens8, and explains the distribution of seismicity observed at the time of the catastrophic eruption in 1980 (refs9, 10). ?? 2009 Macmillan Publishers Limited. All rights reserved.

  19. Tilt networks of Mount Shasta and Lassen Peak, California

    USGS Publications Warehouse

    Dzurisin, Daniel; Johnson, Daniel J.; Murray, T.L.; Myers, Barbara

    1982-01-01

    In response to recent eruptions at Mount St. Helens and with support from the USGS Volcanic Hazards Program, the Cascades Volcano Observatory (CVO) has initiated a program to monitor all potentially-active volcanoes of the Cascade Range. As part of that effort, we installed tilt networks and obtained baseline measurements at Mount Shasta and Lassen Peak, California during July 1981. At the same time, baseline electronic distance measurements (EDM) were made and fumarole surveys were conducted by other crews from CVO. Annual surveys are planned initially, with subsequent visits as conditions warrant. These geodetic and geochemical measurements supplement a program of continuous seismic monitoring of Cascade volcanoes by the USGS Office of Earthquake Studies in cooperation with local universities. Other tilt networks were established at Mount Baker in 1975 and at Mount St. Helens in 1981. EDM networks were established at Mount Baker in 1975, Mount St. Helens in 1980, and Crater Lake in 1981. Additional tilt and/or EDM networks are planned for Mount Rainier, Mount Hood, Glacier Peak, Three Sisters, and Crater Lake as funds permit.

  20. Behold Mount Sharp!

    NASA Image and Video Library

    2012-08-06

    This image taken by NASA Curiosity shows what lies ahead for the rover -- its main science target, informally called Mount Sharp. The rover shadow can be seen in the foreground, and the dark bands beyond are dunes.

  1. Thermal compensating mount

    NASA Technical Reports Server (NTRS)

    Jalink, Antony, Jr. (Inventor); Campbell, Scott R. (Inventor)

    1990-01-01

    The main objective is to provide a device for maintaining the alignment integrity of an alignment sensitive component over a wide range of temperatures. A thermal compensating mount is presented. A cylindrical extension is integrally formed to the alignment sensitive component. Both the extension and component share the same coefficient of thermal expansion. The cylindrical extension is placed into a mounting structure which has a diameter greater than that of the extension. An adhesive secures the cylindrical extension to the mount. The difference between the diameters of the cylindrical extension and the cylindrical receptacle is such that the differential thermal expansion across the extension and the receptacle edges is exactly compensated for by the thermal compensation of the adhesive between them. Accordingly, the alignment sensitive component does not change position when subjected to temperature variations. One application of this invention is laser optical-path folding prisms, which are fixed to the mounting surface by a small amount of epoxy adhesive.

  2. Mounting for ceramic scroll

    DOEpatents

    Petty, Jack D.

    1993-01-01

    A mounting for a ceramic scroll on a metal engine block of a gas turbine engine includes a first ceramic ring and a pair of cross key connections between the first ceramic ring, the ceramic scroll, and the engine block. The cross key connections support the scroll on the engine block independent of relative radial thermal growth and for bodily movement toward an annular mounting shoulder on the engine. The scroll has an uninterrupted annular shoulder facing the mounting shoulder on the engine block. A second ceramic ring is captured between mounting shoulder and the uninterrupted shoulder on the scroll when the latter is bodily shifted toward the mouting shoulder to define a gas seal between the scroll and the engine block.

  3. Seasonality of volcanic eruptions

    NASA Astrophysics Data System (ADS)

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

    2004-04-01

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

  4. 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.

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

    USGS Publications Warehouse

    Hildreth, Wes; Fierstein, Judy

    2012-01-01

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

  6. A Numerical Program for Steady-State Flow of Magma-Gas Mixtures Through Vertical Eruptive Conduits

    DTIC Science & Technology

    2000-01-01

    Numerical Program for Flow in Eruptive Conduits Figure 6: Comparison of results for conduit flow of Mount St. Helens magma using a fragmentation...calculated by independent methods, for a Mount St. Helens magma at 830 C, with 4.6 wt% total water. These plots indicate the accuracy of Conflow in...Nonequilibrium flow in volcanic conduits and application to the eruptions of Mt. St. Helens on May 18, 1980 and Vesuvius in AD 79: Journal of Volcanology and

  7. Violent strombolian and subplinian eruptions at Vesuvius during post-1631 activity

    NASA Astrophysics Data System (ADS)

    Arrighi, Simone; Principe, Claudia; Rosi, Mauro

    2001-06-01

    On the basis of historical chronicles and field investigations the tephrostratigraphic sequence of post-1631 activity of Vesuvius is reconstructed. It has been established that, during this period, in addition to numerous totally effusive eruptions and/or normal strombolian activity, 16 explosive events produced well-traceable tephra deposits in the area outside the Mount Somma caldera. Ages of tephra beds were established on the basis of stratigraphic relationships with historical lava flows and comparison with chroniclers information. The dispersal and lithological characteristics of tephra deposits combined with description of explosive activity lead to the identification of three styles: (a) periods of violent strombolian activity; (b) violent strombolian eruptions; and (c) subplinian eruptions. Violent strombolian eruptions and periods of discrete activity are characterized by the formation of lapilli falls from eruptive columns only some kilometers high. Subplinian eruptions are defined on the basis of their lapilli fall volumes which is of the order of 107 m3, on eruptive column heights of approximately 10 km, bt higher than 1.5, and mass discharged rate values not lower than 106 kg/s. During the first century of activity after the 1631 eruption, two periods of violent strombolian activity occurred at Vesuvius (1682-1707 and 1707-1719) preceded, and followed, by a series of violent strombolian eruptions (1660, 1682, 1707, 1723, 1730, 1790, 1872). Between 1730 and 1779 a relevant change in the eruptive style of Vesuvius occurred by an increase in the explosivity of the eruptions. During the past two centuries of activity, only a few eruptions reached subplinian magnitude and only five eruptions had a phreatomagmatic phase (1779, 1794, 1822, 1906, 1944). Therefore, the previously accepted model of cyclic activity, in which each cycle is closed by an important explosive eruption with phreatomagmatic characteristics, is unfounded. The tephrostratigraphy of the

  8. Psychiatric reactions to disaster: the Mount St. Helens experience.

    PubMed

    Shore, J H; Tatum, E L; Vollmer, W M

    1986-05-01

    Following the 1980 Mount St. Helens volcanic eruption, psychiatric reactions were studied in the disaster area and in a control community. Using the new criterion-based diagnostic method for psychiatric epidemiologic research, the Diagnostic Interview Schedule, the authors found a significant prevalence of disaster-related psychiatric disorders. These Mount St. Helens disorders included depression, generalized anxiety, and posttraumatic stress reaction. There was a progressive "dose-response" relationship in the comparison of control, low-exposure, and high-exposure groups. The dose-response pattern occurred among both the bereaved and the property-loss victims.

  9. Mount Pinatubo, Philippine Islands as seen from STS-59

    NASA Image and Video Library

    1994-04-10

    STS059-L14-170 (9-20 April 1994) --- Orient with the sea at the left. Then Subic Bay is at the lower left corner, and Clark Air Force Base (abandoned after the eruption) is to the lower right of the volcano. A turquoise lake occupies the caldera just below the center of the photograph. Mount Pinatubo erupted in June, 1991 after several hundred years of quiescence. Eruptive activity has nearly ceased, but every torrential rain in this monsoonal climate causes renewed mud flows of a viscous slurry composed of volcanic ash and pumice. Shuttle crews have been photographing the mountain at every opportunity, to add documentation to unmanned-satellite, aerial, and ground-based observations of changes. SRL scientists will use the excellent radar imagery obtained during STS-59 to help discriminate among different kinds of volcanic material, and to extend their observations to other volcanoes around the world using future, perhaps unmanned, radar satellites. Linhof photograph.

  10. Mount St. Helens related aerosol properties from solar extinction measurements

    NASA Technical Reports Server (NTRS)

    Michalsky, J. J.; Kleckner, E. W.; Stokes, G. M.

    1982-01-01

    A network of solar radiometers, operated on the North American Continent for an average of 2 years before the first major eruption of Mount St. Helens, Washington, continues to collect direct solar data through the eruptive phase of this volcano. The radiometers collect spectral data through 12 interference filters spanning the sensitivity of the photodiode used as detector. The data are collected every 5 minutes in seven filters and every 15 minutes in five additional filters. A variant of the classical Langley method has been used to measure the optical depth of the aerosols as a function of wavelength. The network, which is the nearest station, is located some 180 kilometers east of the volcano, well within range of noticeable effects during much of the minor as well as major activity. The wavelength dependence of the aerosol-optical depth before and after the 22 July 1980 major eruption, which was well characterized because of favorable meteorological conditions is discussed.

  11. Volcano hazards in the Mount Hood region, Oregon

    USGS Publications Warehouse

    Scott, W.E.; Pierson, T.C.; Schilling, S.P.; Costa, J.E.; Gardner, C.A.; Vallance, J.W.; Major, J.J.

    1997-01-01

    Mount Hood is a potentially active volcano close to rapidly growing communities and recreation areas. The most likely widespread and hazardous consequence of a future eruption will be for lahars (rapidly moving mudflows) to sweep down the entire length of the Sandy (including the Zigzag) and White River valleys. Lahars can be generated by hot volcanic flows that melt snow and ice or by landslides from the steep upper flanks of the volcano. Structures close to river channels are at greatest risk of being destroyed. The degree of hazard decreases as height above a channel increases, but large lahars can affect areas more than 30 vertical meters (100 vertical feet) above river beds. The probability of eruption-generated lahars affecting the Sandy and White River valleys is 1-in-15 to l-in-30 during the next 30 years, whereas the probability of extensive areas in the Hood River Valley being affected by lahars is about ten times less. The accompanying volcano-hazard-zonation map outlines areas potentially at risk and shows that some areas may be too close for a reasonable chance of escape or survival during an eruption. Future eruptions of Mount Hood could seriously disrupt transportation (air, river, and highway), some municipal water supplies, and hydroelectric power generation and transmission in northwest Oregon and southwest Washington.

  12. On the use of remote infrasound and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption

    SciTech Connect

    Caudron, Corentin; Taisne, Benoit; Garces, Milton

    2015-07-14

    The February 2014 eruption of Kelud volcano (Indonesia) destroyed most of the instruments near it. We use remote seismic and infrasound sensors to reconstruct the eruptive sequence. The first explosions were relatively weak seismic and infrasound events. A major stratospheric ash injection occurred a few minutes later and produced long-lasting atmospheric and ground-coupled acoustic waves that were detected as far as 11,000 km by infrasound sensors and up to 2300 km away on seismometers. A seismic event followed ~12 minutes later and was recorded 7000 km away by seismometers. We estimate a volcanic intensity around 10.9, placing the 2014 Keludmore » eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. As a result, we demonstrate how remote infrasound and seismic sensors are critical for the early detection of volcanic explosions, and how they can help to constrain and understand eruptive sequences.« less

  13. On the use of remote infrasound and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption

    NASA Astrophysics Data System (ADS)

    Taisne, B.; Caudron, C.; Garces, M. A.; Mialle, P.; LE Pichon, A.

    2015-12-01

    The February 2014 eruption of Kelud volcano (Indonesia) destroyed most of the instruments near it. We use remote seismic and infrasound sensors to reconstruct the eruptive sequence. The first explosions were relatively weak seismic and infrasound events. A major stratospheric ash injection occurred a few minutes later and produced long-lasting atmospheric and ground-coupled acoustic waves that were detected as far as 11,000 km by infrasound sensors, and up to 2,300 km away on seismometers. A seismic event followed ~12 minutes later and was recorded 7,000 km away by seismometers. We estimate a volcanic intensity [Pyle,2000] around 10.9, placing the 2014 Kelud eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. We demonstrate how remote infrasound and seismic sensors are critical for the early detection of volcanic explosions, and how they can help to constrain and understand eruptive sequences.

  14. Atmospheric CO2 response to volcanic eruptions: The role of ENSO, season, and variability

    NASA Astrophysics Data System (ADS)

    FröLicher, Thomas Lukas; Joos, Fortunat; Raible, Christoph Cornelius; Sarmiento, Jorge Louis

    2013-01-01

    explosive volcanism is one of the most important natural factors that significantly impact the climate system and the carbon cycle on annual to multi-decadal time scales. The three largest explosive eruptions in the last 50 years—Agung, El Chichón, and Pinatubo—occurred in spring/summer in conjunction with El Niño events and left distinct negative signals in the observational temperature and CO2 records. However, confounding factors such as seasonal variability and El Niño-Southern Oscillation (ENSO) may obscure the forcing-response relationship. We determine for the first time the extent to which initial conditions, i.e., season and phase of the ENSO, and internal variability influence the coupled climate and carbon cycle response to volcanic forcing and how this affects estimates of the terrestrial and oceanic carbon sinks. Ensemble simulations with the Earth System Model (Climate System Model 1.4-carbon) predict that the atmospheric CO2 response is ˜60% larger when a volcanic eruption occurs during El Niño and in winter than during La Niña conditions. Our simulations suggest that the Pinatubo eruption contributed 11 ± 6% to the 25 Pg terrestrial carbon sink inferred over the decade 1990-1999 and -2 ± 1% to the 22 Pg oceanic carbon sink. In contrast to recent claims, trends in the airborne fraction of anthropogenic carbon cannot be detected when accounting for the decadal-scale influence of explosive volcanism and related uncertainties. Our results highlight the importance of considering the role of natural variability in the carbon cycle for interpretation of observations and for data-model intercomparison.

  15. 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.

  16. 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.

  17. Io - Volcanic Eruption

    NASA Technical Reports Server (NTRS)

    1979-01-01

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

  18. Holocene geomagnetic secular variation recorded by volcanic deposits at Mount St. Helens, Washington

    USGS Publications Warehouse

    Hagstrum, J.T.; Hoblitt, R.P.; Gardner, C.A.; Gray, T.E.

    2002-01-01

    A compilation of paleomagnetic data from volcanic deposits of Mount St. Helens is presented in this report. The database is used to determine signature paleomagnetic directions of products from its Holocene eruptive events, to assign sampled units to their proper eruptive period, and to begin the assembly of a much larger database of paleomagnetic directions from Holocene volcanic rocks in western North America. The paleomagnetic results from Mount St. Helens are mostly of high quality, and generally agree with the division of its volcanic deposits into eruptive episodes based on previous geologic mapping and radiocarbon dates. The Muddy River andesite's paleomagnetic direction, however, indicates that it is more likely part of the Pine Creek eruptive period rather than the Castle Creek period. In addition, the Two-Fingers andesite flow is more likely part of the Middle Kalama eruptive period and not part of the Goat Rocks period. The paleomagnetic data from Mount St. Helens and Mount Hood document variation in the geomagnetic field's pole position over the last ~2,500 years. A distinct feature of the new paleosecular variation (PSV) record, similar to the Fish Lake record (Oregon), indicates a sudden change from rapid clockwise movement of the pole about the Earth's spin axis to relatively slow counterclockwise movement at ???800 to 900 years B.P.

  19. Eruption of Kliuchevskoi volcano

    NASA Image and Video Library

    1994-09-30

    STS068-150-045 (30 September 1994) --- (Kliuchevskoi Volcano) The major eruption that began September 30, 1994 (launch day) got almost immediate coverage by the astronauts aboard the Space Shuttle Endeavour. The eruption cloud reached 60,000 feet above sea level, and the winds carried ash as far as 640 miles southeast from the volcano into the North Pacific air routes. This picture was made with a large format Linhof camera. While astronauts used handheld camera's to keep up with the Kamchatka event, instruments in the cargo bay of Endeavour recorded data to support the Space Radar Laboratory (SRL-2) mission.

  20. Primary succession in Mount Pinatubo

    PubMed Central

    Marler, Thomas E; del Moral, Roger

    2013-01-01

    Vegetation structure on the east flank of Mount Pinatubo was investigated to determine the inventory of species at 15 y post-eruption, then to ascertain environmental variables that have influenced the early patterns of primary succession. Unconstrained and constrained ordination methods were used to determine the influence of spatial, elevation, and substrate patterns on vegetation. Vegetation was assigned to one of 3 habitat types. Scours were eroded flat surfaces, terraces were perched flat surfaces, and talus piles were created along the canyon edges as mass waste events. The influence of habitat type on vegetation was multifaceted because they represent different conditions and different histories. The talus piles have preferential access to colonists from the vegetation on the canyon walls above and a more benign microclimate than the exposed terrace and scour sites. Scoured sites on the valley floor exhibited the least vegetation cover, as these substrates had the least mature surfaces and the most restricted capacity for root exploration. Perched terraces exhibited greater plant dominance than did the other habitats in the early stages of succession because of the ubiquitous appearance of Parasponia rugosa as initial colonists on these relatively flat surfaces. Polynomial canonical correspondence analysis was more closely aligned with the pattern of vegetation than linear canonical correspondence analysis, and therefore more closely approximated accurate descriptions of correlations among site ordination positions and measured variables. These results confirm that a variety of statistical approaches can clarify applications for restoration ecology following landslide and volcanic disturbances or agriculture and forestry anthropogenic disturbances in the lowland tropics. PMID:24505499

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  2. An inexpensive focusing mount

    NASA Astrophysics Data System (ADS)

    Missira, A.

    1998-10-01

    A focusing mount with the ability to take a range of government surplus eyepieces was required for a home-made 60mm refractor. After considering machining one from brass bar/tube an almost ready-made solution was found.

  3. Housing And Mounting Structure

    DOEpatents

    Anderson, Gene R.; Armendariz, Marcelino G.; Baca, Johnny R.F.; Bryan, Robert P.; Carson, Richard F.; Duckett, III, Edwin B.; McCormick, Frederick B.; Miller, Gregory V.; Peterson, David W.; Smith, Terrance T.

    2005-03-08

    This invention relates to an optical transmitter, receiver or transceiver module, and more particularly, to an apparatus for connecting a first optical connector to a second optical connector. The apparatus comprises: (1) a housing having at least a first end and at least a second end, the first end of the housing capable of receiving the first optical connector, and the second end of the housing capable of receiving the second optical connector; (2) a longitudinal cavity extending from the first end of the housing to the second end of the housing; and (3) an electromagnetic shield comprising at least a portion of the housing. This invention also relates to an apparatus for housing a flexible printed circuit board, and this apparatus comprises: (1) a mounting structure having at least a first surface and a second surface; (2) alignment ridges along the first and second surfaces of the mounting structure, the alignment ridges functioning to align and secure a flexible printed circuit board that is wrapped around and attached to the first and second surfaces of the mounting structure; and (3) a series of heat sink ridges adapted to the mounting structure, the heat sink ridges functioning to dissipate heat that is generated from the flexible printed circuit board.

  4. The Geologic Story of Mount Rainier

    USGS Publications Warehouse

    Crandell, Dwight Raymond

    1969-01-01

    Ice-clad Mount Rainier, towering over the landscape of western Washington, ranks with Fuji-yama in Japan, Popocatepeti in Mexico, and Vesuvius in Italy among the great volcanoes of the world. At Mount Rainier, as at other inactive volcanoes, the ever-present possibility of renewed eruptions gives viewers a sense of anticipation, excitement, and apprehension not equaled by most other mountains. Even so, many of us cannot imagine the cataclysmic scale of the eruptions that were responsible for building the giant cone which now stands in silence. We accept the volcano as if it had always been there, and we appreciate only the beauty of its stark expanses of rock and ice, its flower-strewn alpine meadows, and its bordering evergreen forests.Mount Rainier owes its scenic beauty to many features. The broad cone spreads out on top of a major mountain range - the Cascades. The volcano rises about 7,000 feet above its 7,000-foot foundation, and stands in solitary splendor - the highest peak in the entire Cascade Range. Its rocky ice-mantled slopes above timberline contrast with the dense green forests and give Mount Rainier the appearance of an arctic island in a temperate sea, an island so large that you can see its full size and shape only from the air. The mountain is highly photogenic because of the contrasts it offers among bare rock, snowfields, blue sky, and the incomparable flower fields that color its lower slopes, shadows cast by the multitude of cliffs, ridges, canyons, and pinnacles change constantly from sunrise to sunset, endlessly varying the texture and mood of the mountain. The face of the mountain also varies from day to day as its broad snowfields melt during the summer. The melting of these frozen reservoirs makes Mount Rainier a natural resource in a practical as well as in an esthetic sense, for it ensures steady flows of water for hydroelectric power in the region, regardless of season.Seen from the Puget Sound country to the west, Mount Rainier has

  5. ASTER Images Merapi Continuing Eruption

    NASA Image and Video Library

    2010-11-18

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

  6. Katmai volcanic cluster and the great eruption of 1912

    USGS Publications Warehouse

    Hildreth, W.; Fierstein, J.

    2000-01-01

    In June 1912, the world's largest twentieth century eruption broke out through flat-lying sedimentary rocks of Jurassic age near the base of Trident volcano on the Alaska Peninsula. The 60 h ash-flow and Plinian eruptive sequence excavated and subsequently backfilled with ejecta a flaring funnel-shaped vent since called Novarupta. The vent is adjacent to a cluster of late Quaternary stratocones and domes that have released about 140 km3 of magma in the past 150 k.y. Although the 1912 vent is closest to the Trident group and is also close to Mageik and Griggs volcanoes, it was the summit of Mount Katmai, 10 km east of Novarupta, that collapsed during the eruption to form a 5.5 km3 caldera. Many earthquakes, including 14 in the range M 6-7, took place during and after the eruption, releasing 250 times more seismic energy than the 1991 caldera-forming eruption of the Philippine volcano, Pinatubo. The contrast in seismic behavior may reflect the absence of older caldera faults at Mount Katmai, lack of upward (subsidence opposing) magma flow owing to lateral magma withdrawal in 1912, and the horizontally stratified structure of the thick shale-rich Mesozoic basement. The Katmai caldera compensates for only 40% of the 13 km3 of 1912 magma erupted, which included 7-8 km3 of slightly zoned high-silica rhyolite and 4.5 km3 of crystal-rich dacite that grades continuously into 1 km3 of crystal-rich andesite. We have now mapped, sampled, and studied the products of all 20 components of the Katmai volcanic cluster. Pyroxene dacite and silicic andesite predominate at all of them, and olivine andesite is also common at Griggs, Katmai, and Trident volcanoes, but basalt and rhyodacite have erupted only at Mount Katmai. Rhyolite erupted only in 1912 and is otherwise absent among Quaternary products of the cluster. Pleistocene products of Mageik and Trident and all products of Griggs are compositionally distinguishable from those of 1912 at Novarupta. Holocene products of Mount

  7. Benefits of volcano monitoring far outweigh costs - the case of Mount Pinatubo

    USGS Publications Warehouse

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

    1997-01-01

    The climactic June 1991 eruption of Mount Pinatubo, Philippines, was the largest volcanic eruption in this century to affect a heavily populated area. Because it was forecast by scientists from the Philippine Institute of Volcanology and Seismology and the U.S. Geological Survey, civil and military leaders were able to order massive evacuations and take measures to protect property before the eruption. Thousands of lives were saved and hundreds of millions of dollars in property losses averted. The savings in property alone were many times the total costs of the forecasting and evacuations.

  8. Impaired tooth eruption: a review.

    PubMed

    Noffke, C E E; Chabikuli, N J; Nzima, N

    2005-11-01

    Eruption is the continuous process of movement of a tooth from its developmental location inside the jaw to its functional location in the mouth. Impaired tooth eruption, where this process is disturbed, is common in dental practice. It may manifest either as delayed or complete absence of eruption. Although unerupted teeth are usually asymptomatic, they may cause cosmetic and pathologic complications. The purpose of this article is to provide a review on the pathogenesis and differential radiographic interpretation of impaired tooth eruption.

  9. Legendary Mount Vesuvius is subject of intensive volcanological study

    NASA Astrophysics Data System (ADS)

    Spera, Frank

    The Roman population centers of Pompeii and Herculaneum (circa 15,000 inhabitants) were destroyed when Mount Vesuvius erupted in 79 A.D. after centuries of repose. Many times since then its eruptions have claimed human lives; basaltic lava flows from an eruption in 1631 killed 3,000. Vesuvius' location, near the heart of the Roman empire—a center of learning in the ancient world—led it to become the site ofsome of the earliest volcanological studies on record.In letters to Tacitus, Pliny the Younger documented the sequence of events of the 79 A.D. plinian eruption. Geophysical studies of volcanoes were pioneered by Italian volcanologists who installed seismographs in an observatory on the flanks of Vesuvius to study volcano seismology and to forecast and monitor eruptions early this century. It is easy to understand why interest in Vesuvius has been so keen: it is accessible, persistently active, and a large population resides nearby. Today, around 1 million people live within the shadow of this potentially explosive and dangerous volcano.

  10. Prospects for eruption prediction in near real-time

    USGS Publications Warehouse

    Voight, B.; Cornelius, R.R.

    1991-01-01

    THE 'materials science' method for eruption prediction1-3 arises from the application of a general law governing the failure of materials: ??-?? ??-A=0, where A and ?? are empirical constants, and ?? is an observable quantity such as ground deformation, seismicity or gas emission. This law leads to the idea of the 'inverse-rate' plot, in which the time of failure can be estimated by extrapolation of the curve of ??-1 versus time to a pre-deter-mined intercept. Here we suggest that this method can be combined with real-time seismic amplitude monitoring to provide a tool for near-real-time eruption prediction, and we demonstrate how it might have been used to predict two dome-growth episodes at Mount St Helens volcano in 1985 and 1986, and two explosive eruptions at Redoubt volcano in 1989-90.

  11. 4D simulation of explosive eruption dynamics at Vesuvius

    NASA Astrophysics Data System (ADS)

    Neri, Augusto; Esposti Ongaro, Tomaso; Menconi, Gianluca; De'Michieli Vitturi, Mattia; Cavazzoni, Carlo; Erbacci, Giovanni; Baxter, Peter J.

    2007-02-01

    We applied a new simulation model, based on multiphase transport laws, to describe the 4D (3D spatial coordinates plus time) dynamics of explosive eruptions. Numerical experiments, carried out on a parallel supercomputer, describe the collapse of the volcanic eruption column and the propagation of pyroclastic density currents (PDCs), for selected medium scale (sub-Plinian) eruptive scenarios at Vesuvius, Italy. Simulations provide crucial insights into the effects of the generation mechanism of the flows - partial collapse vs boiling-over - on their evolution and hazard potential, the unstable dynamics of the fountain, and the influence of Mount Somma on the propagation of PDCs into the circum-Vesuvian area, one of the world's most hazardous volcanic settings. Results also show that it is possible to characterize the volcanic column behavior in terms of percentage of the mass of pyroclasts collapsed to the ground and how this parameter strongly influences the dynamics and hazard of the associated PDCs.

  12. 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.

  13. Eruption on Io

    NASA Technical Reports Server (NTRS)

    1996-01-01

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

  14. 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.

  15. Mount St. Helens' volcanic ash: hemolytic activity.

    PubMed

    Vallyathan, V; Mentnech, M S; Stettler, L E; Dollberg, D D; Green, F H

    1983-04-01

    Volcanic ash samples from four Mount St. Helens' volcanic eruptions were subjected to mineralogical, analytical, and hemolytic studies in order to evaluate their potential for cytotoxicity and fibrogenicity. Plagioclase minerals constituted the major component of the ash with free crystalline silica concentrations ranging from 1.5 to 7.2%. The in vitro hemolytic activity of the volcanic ash was compared to similar concentrations of cytotoxic and inert minerals. The ash was markedly hemolytic, exhibiting an activity similar to chrysotile asbestos, a known fibrogenic agent. The hemolysis of the different ash samples varied with particle size but not with crystalline silica concentration. The results of these studies taken in conjunction with the results of our animal studies indicate a fibrogenic potential of volcanic ash in heavily exposed humans.

  16. Mount Rainier: living safely with a volcano in your backyard

    USGS Publications Warehouse

    Driedger, Carolyn L.; Scott, William E.

    2008-01-01

    Majestic Mount Rainier soars almost 3 miles (14,410 feet) above sea level and looms over the expanding suburbs of Seattle and Tacoma, Washington. Each year almost two million visitors come to Mount Rainier National Park to admire the volcano and its glaciers, alpine meadows, and forested ridges. However, the volcano's beauty is deceptive - U.S. Geological Survey (USGS) research shows that Mount Rainier is one of our Nation's most dangerous volcanoes. It has been the source of countless eruptions and volcanic mudflows (lahars) that have surged down valleys on its flanks and buried broad areas now densely populated. To help people live more safely with the volcano, USGS scientists are working closely with local communities, emergency managers, and the National Park Service.

  17. Impact of major volcanic eruptions on stratospheric water vapour

    NASA Astrophysics Data System (ADS)

    Löffler, Michael; Brinkop, Sabine; Jöckel, Patrick

    2016-05-01

    Volcanic eruptions can have a significant impact on the Earth's weather and climate system. Besides the subsequent tropospheric changes, the stratosphere is also influenced by large eruptions. Here changes in stratospheric water vapour after the two major volcanic eruptions of El Chichón in Mexico in 1982 and Mount Pinatubo on the Philippines in 1991 are investigated with chemistry-climate model simulations. This study is based on two simulations with specified dynamics of the European Centre for Medium-Range Weather Forecasts Hamburg - Modular Earth Submodel System (ECHAM/MESSy) Atmospheric Chemistry (EMAC) model, performed within the Earth System Chemistry integrated Modelling (ESCiMo) project, of which only one includes the long-wave volcanic forcing through prescribed aerosol optical properties. The results show a significant increase in stratospheric water vapour induced by the eruptions, resulting from increased heating rates and the subsequent changes in stratospheric and tropopause temperatures in the tropics. The tropical vertical advection and the South Asian summer monsoon are identified as sources for the additional water vapour in the stratosphere. Additionally, volcanic influences on tropospheric water vapour and El Niño-Southern Oscillation (ENSO) are evident, if the long-wave forcing is strong enough. Our results are corroborated by additional sensitivity simulations of the Mount Pinatubo period with reduced nudging and reduced volcanic aerosol extinction.

  18. Geologic map of Mount Gareloi, Gareloi Island, Alaska

    USGS Publications Warehouse

    Coombs, Michelle L.; McGimsey, Robert G.; Browne, Brandon L.

    2012-01-01

    As part of an effort to both monitor and study all historically active volcanoes in Alaska, the Alaska Volcano Observatory (AVO) undertook a field program at Mount Gareloi in the summer of 2003. During a month-long period, seismic networks were installed at Mount Gareloi and the neighboring Tanaga volcanic cluster. During this time, we undertook the first geologic field study of the volcano since Robert Coats visited Gareloi Island for four days in 1946. Understanding the geology of this relatively small island is important from a hazards perspective, because Mount Gareloi lies beneath a heavily trafficked air route between North America and Asia and has frequently erupted airborne ash since 1760. At least two landslides from the island have deposited debris on the sea floor; thus, landslide-generated tsunamis are also a potential hazard. Since seismic instruments were installed in 2003, they have detected small but consistent seismic signals from beneath Mount Gareloi's edifice, suggesting an active hydrothermal system. Mount Gareloi is also important from the standpoint of understanding subduction-related volcanism, because it lies in the western portion of the volcanically active arc, where subduction is oblique to the arc front. Understanding the compositional evolution of Mount Gareloi fills a spatial gap in along-arc studies.

  19. [Tooth eruption disturbances and syndromes].

    PubMed

    Oosterkamp, B C M; Ockeloen, C W; Carels, C E L; Kuijpers-Jagtman, A M

    2014-04-01

    In the tooth eruption mechanism, various disturbances can appear as a result of gene mutations, a consequence of which can be that tooth eruption does not occur. There are 5 syndromes which involve the complete failure of several or even all teeth to erupt, specifically: cleidocranial dysplasia, Gardner's syndrome, osteopetrosis, mucopolysaccharidosis and GAPO syndrome. Some are very rare and will seldom be encountered in a dental practice, but they show how vulnerable the tooth eruption mechanism is. Dentists are generally the ones who identify a tooth eruption problem in a patient. Since syndromes can be associated with other disorders, additional investigation by a clinical geneticist is always important when a syndrome is suspected.

  20. Mount Pinatubo, Philippines

    NASA Image and Video Library

    1994-09-30

    STS068-232-083 (30 September-11 October 1994) --- This is a view of Mount Pinatubo, Philippine Islands, orient with the coast to the top. View westward across central Luzon and Mount Pinatubo. Manilla Bay is in partial sunglint along the left edge of the frame. The extensive flows of volcanic ash (lahars) extending from the mountain are readily seen despite partial cloud cover. The ash is mobilized with every rain in this typhoon-ridden region, flowing down valleys, filling drainage channels, and covering fields and towns. The STS-68 crew obtained excellent photographs of the region, for comparison to the radar data also obtained on the mission. Photographs in sunglint have proven particularly helpful because they show the exact outlines of surface water, which provides a datum point for the radar returns.

  1. Observations of volcanic tremor at Mount St. Helens volcano

    SciTech Connect

    Fehler, M.

    1983-04-10

    Digital recordings of ground motion during tremor episodes accompanying eruptions at Mount St. Helens Volcano in the state of Washington on August 7 and October 16-18, 1980, are studied. The spectra of the vertical component waveforms contain at least two dominant peaks at 1.0 and 1.3 Hz for all events recorded during both eruptions that were studied. Spectra of horizontal ground motion show peaks at 0.9 and 1.1 Hz. The relative amplitude of the two peaks changes between tremor episodes and during single tremor episodes and shows no consistent relation to amplitude of ground motion. Spectra of long-period earthquakes aremore » very similar to those of tremor events, suggesting that tremor is composed of many long-period earthquakes that occur over a period of time. The unique waveform of tremor events observed at Mount St. Helens must be due to a source effect, since the relative amplitude of the two dominant peaks changes during tremor episodes. The path effect on tremor waveforms is small since there are no peaks in the spectra of waveforms recorded during tectonic earthquakes occurring in the vicinity of Mount S. Helens. The consistency of the location of the spectral peaks for the wide range of tremor amplitudes means that there must be a physical length at the source that is constant, independent of the amplitude of motion at the source. Amplitude of ground motion varies between 0.11 and 4.7 ..mu..m. Seismic moment rates during the two eruptions are found to vary between 6 x 10/sup 18/ and 1 x 10/sup 20/ dynes cm/s. Study of tremor amplitudes recorded at Corvallis, Oregon, leads to the conclusion that tremor accompanying the cataclysmic May 18, 1980, eruption was at least one order of magnitude larger in amplitude than tremor during August and October.« less

  2. Surficial Geologic Map of Mount Veniaminof Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Miller, T. P.; Wallace, K.

    2015-12-01

    Mount Veniaminof volcano is a >300 km3 andesite to dacite stratovolcano, characterized by an 8 x 11 km diameter ice-filled summit caldera. Veniaminof is one of the most active volcanoes in the Aleutian arc and has erupted at least 15 times in the past 200 years. The volcano is located on the Alaska Peninsula (56.1979° N, 159.3931° W) about 780 km SW of Anchorage. Our geologic investigations have documented two large (>VEI 5) caldera-forming or -modifying eruptions (V1, V2) of Holocene age whose eruptive products make up most of the surficial deposits around the volcano. These deposits and other unconsolidated glacial, fluvial, and colluvial deposits are depicted on the accompanying map. The the V2 eruption occurred 4.1-4.4 ka (cal 2-sigma age range) and produced an extensive landscape-mantling sequence of pyroclastic deposits >50 km3 in volume that cover or partly obscure older unconsolidated eruptive products. The V1 eruption occurred 8-9 ka and its deposits lie stratigraphically below the pyroclastic deposits associated with the V2 eruption and a prominent, widespread tephra fall deposit erupted from nearby Black Peak volcano 4.4-4.6 ka. The V2 pyroclastic-flow deposits range from densely welded, columnar jointed units exposed along the main valley floors, to loose, unconsolidated, blanketing accumulations of scoriaceous (55-57% SiO2) and lithic material found as far as 75 km from the edifice. Large lahars also formed during the V2 eruption and flowed as far as 50 km from the volcano. The resulting deposits are present in all glacial valleys that head on the volcano and are 10-15 m thick in several locations. Lahar deposits cover an area of about 800-1000 km2, have an approximate volume of 1-2 km3, and record substantial inundation of the major valleys on all flanks of the edifice. Significant amounts of water are required to form lahars of this size, which suggests that an ice-filled summit caldera probably existed when the V2 eruption occurred.

  3. EMU helmet mounted display

    NASA Technical Reports Server (NTRS)

    Marmolejo, Jose (Inventor); Smith, Stephen (Inventor); Plough, Alan (Inventor); Clarke, Robert (Inventor); Mclean, William (Inventor); Fournier, Joseph (Inventor)

    1990-01-01

    A helmet mounted display device is disclosed for projecting a display on a flat combiner surface located above the line of sight where the display is produced by two independent optical channels with independent LCD image generators. The display has a fully overlapped field of view on the combiner surface and the focus can be adjusted from a near field of four feet to infinity.

  4. Plasma Screen Floating Mount

    DOEpatents

    Eakle, Robert F.; Pak, Donald J.

    2004-10-26

    A mounting system for a flat display screen, particularly a plasma display screen, suspends the screen separately in each of the x-, y- and z-directions. A series of frames located by linear bearings and isolated by springs and dampers allows separate controlled movement in each axis. The system enables the use of relatively larger display screens in vehicles in which plasma screen are subject to damage from vibration.

  5. Mount Kilimanjaro, Tanzania

    NASA Image and Video Library

    1996-01-20

    STS072-722-004 (11-20 Jan. 1996) --- Mount Kilimanjaro in Tanzania is featured in this 70mm frame exposed from the Earth-orbiting Space Shuttle Endeavour. Orient with the clouds trailing to the left; then the view is southwest from Kenya past Kilimanjaro to Mount Meru, in Tanzania. Mount Kilimanjaro is about three degrees south of the Equator, but at nearly 6,000 meters has a permanent snowfield. The mountain displays a classic zonation of vegetation types from seasonally dry savannah on the plains at 1,000 meters, to the cloud forest near the top. The mountain is being managed experimentally as an international biosphere reserve. A buffer zone of "traditional" agriculture and pastoral land use is designated around the closed-canopy forest reserve. Specialists familiar with this area say management is partially successful so far, but cleared areas of the forest can be seen on this photograph as light green "nibbles" or "cookie cuts" extending into the dark forest region.

  6. Reconstruction of the 2014 eruption sequence of Ontake Volcano from recorded images and interviews

    NASA Astrophysics Data System (ADS)

    Oikawa, Teruki; Yoshimoto, Mitsuhiro; Nakada, Setsuya; Maeno, Fukashi; Komori, Jiro; Shimano, Taketo; Takeshita, Yoshihiro; Ishizuka, Yoshihiro; Ishimine, Yasuhiro

    2016-05-01

    A phreatic eruption at Mount Ontake (3067 m) on September 27, 2014, led to 64 casualties, including missing people. In this paper, we clarify the eruption sequence of the 2014 eruption from recorded images (photographs and videos obtained by climbers) and interviews with mountain guides and workers in mountain huts. The onset of eruption was sudden, without any clear precursory surface phenomena (such as ground rumbling or strong smell of sulfide). Our data indicate that the eruption sequence can be divided into three phases. Phase 1: The eruption started with dry pyroclastic density currents (PDCs) caused by ash column collapse. The PDCs flowed down 2.5 km SW and 2 km NW from the craters. In addition, PDCs moved horizontally by approximately 1.5 km toward N and E beyond summit ridges. The temperature of PDCs at the summit area partially exceeded 100 °C, and an analysis of interview results suggested that the temperature of PDCs was mostly in the range of 30-100 °C. At the summit area, there were violent falling ballistic rocks. Phase 2: When the outflow of PDCs stopped, the altitude of the eruption column increased; tephra with muddy rain started to fall; and ambient air temperature decreased. Falling ballistic rocks were almost absent during this phase. Phase 3: Finally, muddy hot water flowed out from the craters. These models reconstructed from observations are consistent with the phreatic eruption models and typical eruption sequences recorded at similar volcanoes.

  7. Eruption of Kliuchevskoi volcano

    NASA Image and Video Library

    1994-09-30

    STS068-214-035 (30 September 1994) --- One of the first photos taken by the crewmembers on launch day of the Space Shuttle Endeavour was this 70mm frame of the Kliuchevskoi volcano on the Kamchatka Peninsula in Russia. The volcano was near its peak at this time. The large, black eruption plume billows from the summit, as ash is being deposited on the snow-covered region to the east and southeast (north is to upper left). A small steam plume rises from the peak of Bezymianny just south of Kliuchevskoi (or just right of center). As various members of the six-person crew were using handheld cameras to record the eruption, hardware in Endeavour's cargo bay was taking radar data of the event in support of the Space Radar Laboratory (SRL-2) project.

  8. 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.

  9. Who discovered Mount Everest?

    NASA Astrophysics Data System (ADS)

    Dickey, Parke A.

    The discovery that Mount Everest is the highest mountain in the world was made by the officers of the Survey of India. This organization measured a network of triangulation across India between 1800 and 1870. In order to reduce the measurements to geodetic coordinates, it was necessary to determine the size and shape of the earth. This was accomplished by measuring the length of an arc of the meridian under the direction of the Surveyor General, Sir George Everest. This measurement disagreed with the observations of the stars for latitude by 5 seconds of arc (530 ft or 162 m). In 1855, Pratt and Airy pointed out that the discrepancy was due to the gravitational effect of the Himalayas. Their work was the first indication that the material of the earth's crust under the mountains is lighter than that under plains. During the course of the survey the officers made observations on the snowy Himalayas. They were excluded from Nepal; observations had to be taken from more than 100 mi (160 km) away in jungles infested by malaria. Mount Everest was observed by three different officers between November 27, 1847, and January 17, 1850. The height of the mountain had to be determined by the (human) computers in the survey headquarters in Dehra Dun. The fact that it is the highest mountain in the Himalayas, and probably in the world, was announced by Surveyor General Andrew Waugh in 1856. It is not clear whether the chief computer who made the calculations was an Indian, Radanath Sikhdar, or an Englishman born in India of an Indian mother, John B. N. Hennesy. The local name for the mountain, if it had any, was unknown, so Waugh named it Mount Everest, in honor of the great scientist who was largely responsible for the accomplishments of the Survey of India.

  10. MOUNT WASHINGTON WILDERNESS, OREGON.

    USGS Publications Warehouse

    Taylor, Edward M.; Causey, J. Douglas

    1984-01-01

    On the basis of a mineral survey, Mount Washington Wilderness, Oregon has little promise for the occurrence of metallic mineral or fossil fuel resources. Abundant cinder resources occur in the wilderness, but other large volume cinder deposits are available outside the wilderness and closer to markets. Analysis of the geothermal potential of the High Cascades province cannot be made without data on the subsurface thermal and hydrologic regimes which can only be provided by deep drill holes. Several deep holes could be drilled in areas outside the wildernesses of the High Cascades, from which extrapolations of the geothermal potential of the wildernesses could be made.

  11. Manipulator mounted transfer platform

    SciTech Connect

    Dobbins, J.C.; Hoover, M.A.; May, K.W.

    1990-01-23

    The patent describes in a manipulator system for use in hazardous environments including a manipulator adapted for reciprocal movement upon a guide device, a transfer platform. It comprises: a bed frame defining a generally horizontal bed projecting outwardly from the manipulator; and frame mounting means securing the bed frame to the manipulator in a generally cantilevered fashion, thereby essentially minimizing the structure necessary to support the platform outwardly of the manipulator while enhancing operator visibility of the platform and the manipulator during use of the manipulator system.

  12. Posteruption arthropod succession on the Mount St. Helens volcano: the ground-dwelling beetle fauna (Coleoptera).

    Treesearch

    R.R. Parmenter; C.M. Crisafulli; N. Korbe; G. Parsons; M. Edgar; J.A. MacMahon

    2005-01-01

    The 1980 eruptions of Mount St. Helens created a complex mosaic of disturbance types over a 600 km2 area. From 1980 through 2000 we monitored beetle species relative abundance and faunal composition of assemblages at undisturbed reference sites and in areas subjected to tephra-fall, blowdown, and pyroclastic flow volcanic disturbance. We...

  13. Evolution of Crater Glacier, Mount St. Helens, Washington, September 2006-November 2009

    USGS Publications Warehouse

    Walder, Joseph S.; Schilling, Steven P.; Sherrod, David R.; Vallance, James W.

    2010-01-01

    Lava-dome emplacement through a glacier was observed for the first time during the 2004-08 eruption of Mount St. Helens and documented using photography, photogrammetry, and geodetic measurements. Previously published reports present such documentation through September 2006; this report extends that documentation until November 2009.

  14. Contingency Planning for Natural Disasters: The Mount St. Helens Experience. AIR Forum 1981 Paper.

    ERIC Educational Resources Information Center

    Burns, James A.; Concordia, Louis R.

    The effectiveness of existing contingency planning efforts at five community colleges, three colleges, and five universities during the Mount St. Helens eruptions in 1980 in Washington state was assessed. Planning efforts in the areas of institutional policy, academic policy, business office, physical plant, residence halls, financial aid, and…

  15. Surface mount component jig

    DOEpatents

    Kronberg, James W.

    1990-08-07

    A device for bending and trimming the pins of a dual-inline-package component and the like for surface mounting rather than through mounting to a circuit board comprises, in a first part, in pin cutter astride a holder having a recess for holding the component, a first spring therebetween, and, in a second part, two flat members pivotally interconnected by a hinge and urged to an upward peaked position from a downward peaked position by a second spring. As a downward force is applied to the pin cutter it urges the holder downward, assisted by the first spring and a pair of ridges riding on shoulders of the holder, to carry the component against the upward peaked flat members which guide the pins outwardly. As the holder continues downwardly, the flat members pivot to the downward peaked position bending the pins upwardly against the sides of the holder. When the downward movement is met with sufficient resistance, the ridges of the pin cutter ride over the holder's shoulders to continue downward to cut any excess length of pin.

  16. Clamp-mount device

    NASA Technical Reports Server (NTRS)

    Clark, K. H. (Inventor)

    1983-01-01

    A clamp-mount device is disclosed for mounting equipment to an associated I-beam and the like structural member of the type having oppositely extending flanges wherein the device comprises a base and a pair of oppositely facing clamping members carried diagonally on the base clamping flanges therebetween and having flange receiving openings facing one another. Lock means are carried diagonally by the base opposite the clamping members locking the flanges in the clamping members. A resilient hub is carried centrally of the base engaging and biasing a back side of the flanges maintaining tightly clamped and facilitating use on vertical as well as horizontal members. The base turns about the hub to receive the flanges within the clamping members. Equipment may be secured to the base by any suitable means such as bolts in openings. Slidable gate latches secure the hinged locks in an upright locking position. The resilient hub includes a recess opening formed in the base and a rubber-like pad carried in this opening being depressably and rotatably carried therein.

  17. 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.

  18. Will Teide erupt again?

    NASA Astrophysics Data System (ADS)

    Marti, Joan; Geyer, Adelina

    2016-04-01

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

  19. Anaglyph with Landsat Overlay, Mount Meru, Tanzania

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Mount Meru is an active volcano located just 70 kilometers (44 miles) west of Mount Kilimanjaro. It reaches 4,566 meters (14,978 feet) in height but has lost much of its bulk due to an eastward volcanic blast sometime in its distant past, perhaps similar to the eruption of Mount Saint Helens in Washington State in 1980. Mount Meru most recently had a minor eruption about a century ago. The several small cones and craters seen in the vicinity probably reflect numerous episodes of volcanic activity. Mount Meru is the topographic centerpiece of Arusha National Park, but Ngurdoto Crater to the east (image top) is also prominent. The fertile slopes of both volcanoes rise above the surrounding savanna and support a forest that hosts diverse wildlife, including nearly 400 species of birds, and also monkeys and leopards, while the floor of Ngurdoto Crater hosts herds of elephants and buffaloes.

    The stereoscopic effect of this anaglyph was created by first draping a Landsat satellite image over a digital elevation data from the Shuttle Radar Topography Mission (SRTM), and then generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

    Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter (98-foot) resolution of most Landsat images and will substantially help in analyzing the large and growing Landsat image archive, managed by the U.S. Geological Survey (USGS).

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space

  20. Mount Sharp 'Photobombs' Curiosity

    NASA Image and Video Library

    2018-01-31

    This self-portrait of NASA's Curiosity Mars rover shows the vehicle on Vera Rubin Ridge, which it's been investigating for the past several months. Directly behind the rover is the start of a clay-rich slope scientists are eager to begin exploring. In the coming week, Curiosity will begin to climb this slope. North is on the left and west is on the right, with Gale Crater's rim on the horizon of both edges. Poking up just behind Curiosity's mast is Mount Sharp, photobombing the robot's selfie. Curiosity landed on Mars five years ago with the intention of studying lower Mount Sharp, where it will remain for all of its time on Mars. The mountain's base provides access to layers formed over millions of years. These layers formed in the presence of water -- likely due to a lake or lakes that sat at the bottom of the mountain, which sits inside of Gale Crater. This mosaic was assembled from dozens of images taken by Curiosity's Mars Hands Lens Imager (MAHLI). They were all taken on Jan. 23, 2018, during Sol 1943. The view does not include the rover's arm nor the MAHLI camera itself, except in the miniature scene reflected upside down in the parabolic mirror at the top of the mast. That mirror is part of Curiosity's Chemistry and Camera (ChemCam) instrument. MAHLI appears in the center of the mirror. Wrist motions and turret rotations on the arm allowed MAHLI to acquire the mosaic's component images. The arm was positioned out of the shot in the images, or portions of images, that were used in this mosaic. A full-resolution image is available at https://photojournal.jpl.nasa.gov/catalog/PIA22207

  1. Dynamics of seismogenic volcanic extrusion at Mount St Helens in 2004-05

    USGS Publications Warehouse

    Iverson, R.M.; Dzurisin, D.; Gardner, C.A.; Gerlach, T.M.; LaHusen, R.G.; Lisowski, M.; Major, J.J.; Malone, S.D.; Messerich, J.A.; Moran, S.C.; Pallister, J.S.; Qamar, A.I.; Schilling, S.P.; Vallance, J.W.

    2006-01-01

    The 2004-05 eruption of Mount St Helens exhibited sustained, near-equilibrium behaviour characterized by relatively steady extrusion of a solid dacite plug and nearly periodic shallow earthquakes. Here we present a diverse data set to support our hypothesis that these earthquakes resulted from stick-slip motion along the margins of the plug as it was forced incrementally upwards by ascending, solidifying, gas-poor magma. We formalize this hypothesis with a dynamical model that reveals a strong analogy between behaviour of the magma-plug system and that of a variably damped oscillator. Modelled stick-slip oscillations have properties that help constrain the balance of forces governing the earthquakes and eruption, and they imply that magma pressure never deviated much from the steady equilibrium pressure. We infer that the volcano was probably poised in a near-eruptive equilibrium state long before the onset of the 2004-05 eruption. ??2006 Nature Publishing Group.

  2. Deep earthquakes beneath mount st. Helens: evidence for magmatic gas transport?

    PubMed

    Weaver, C S; Zollweg, J E; Malone, S D

    1983-09-30

    Small-magnitude earthquakes began beneath Mount St. Helens 40 days before the eruption of 20 March 1982. Unlike earlier preeruption seismicity for this volcano, which had been limited to shallow events (less than 3 kilometers), many of these earthquakes were deep (between 5 and 11 kilometers). The location of these preeruptive events at such depth indicates that a larger volume of the volcanic system was affected prior to the 20 March eruption than prior to any of the earlier dome-building eruptions. The depth-time relation between the deep earthquakes and the explosive onset of the eruption is compatible with the upward migration of magmatic gas released from a separate deep reservoir.

  3. Dynamics of seismogenic volcanic extrusion at Mount St Helens in 2004-05.

    PubMed

    Iverson, Richard M; Dzurisin, Daniel; Gardner, Cynthia A; Gerlach, Terrence M; LaHusen, Richard G; Lisowski, Michael; Major, Jon J; Malone, Stephen D; Messerich, James A; Moran, Seth C; Pallister, John S; Qamar, Anthony I; Schilling, Steven P; Vallance, James W

    2006-11-23

    The 2004-05 eruption of Mount St Helens exhibited sustained, near-equilibrium behaviour characterized by relatively steady extrusion of a solid dacite plug and nearly periodic shallow earthquakes. Here we present a diverse data set to support our hypothesis that these earthquakes resulted from stick-slip motion along the margins of the plug as it was forced incrementally upwards by ascending, solidifying, gas-poor magma. We formalize this hypothesis with a dynamical model that reveals a strong analogy between behaviour of the magma-plug system and that of a variably damped oscillator. Modelled stick-slip oscillations have properties that help constrain the balance of forces governing the earthquakes and eruption, and they imply that magma pressure never deviated much from the steady equilibrium pressure. We infer that the volcano was probably poised in a near-eruptive equilibrium state long before the onset of the 2004-05 eruption.

  4. Snaking Filament Eruption [video

    NASA Image and Video Library

    2014-11-14

    A filament (which at one point had an eerie similarity to a snake) broke away from the sun and out into space (Nov. 1, 2014). The video covers just over three hours of activity. This kind of eruptive event is called a Hyder flare. These are filaments (elongated clouds of gases above the sun's surface) that erupt and cause a brightening at the sun's surface, although no active regions are in that area. It did thrust out a cloud of particles but not towards Earth. The images were taken in the 304 Angstrom wavelength of extreme UV light. Credit: NASA/Solar Dynamics Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  5. Snaking Filament Eruption

    NASA Image and Video Library

    2014-11-14

    A filament (which at one point had an eerie similarity to a snake) broke away from the sun and out into space (Nov. 1, 2014). The video covers just over three hours of activity. This kind of eruptive event is called a Hyder flare. These are filaments (elongated clouds of gases above the sun's surface) that erupt and cause a brightening at the sun's surface, although no active regions are in that area. It did thrust out a cloud of particles but not towards Earth. The images were taken in the 304 Angstrom wavelength of extreme UV light. Credit: NASA/Solar Dynamics Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  6. 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

  7. Application of computer-assisted mapping to volcanic hazard evaluation of surge eruptions: Vulcano, lipari, and vesuvius

    NASA Astrophysics Data System (ADS)

    Sheridan, Michael F.; Malin, Michael C.

    1983-09-01

    A previously developed computer-assisted model has been applied to several pyroclastic-surge eruptions at three active volcanoes in Italy. Model hazard maps created for various vent locations, eruption types, and mass production rates reasonably reproduced pyroclastic-surge deposits from several recent eruptions on Vulcano, Lipari, and Vesuvius. Small-scale phreatic eruptions on the island of Vulcano (e.g. the 1727 explosion of Forgia Vecchia) pose a limited but serious threat to the village of Porto. The most dangerous zone affected by this type of eruption follows a NNW fissure system between Fossa and Vulcanello. Moderate-sized eruptions on Vulcano, such as those associated with the present Fossa Crater are a much more serious threat to Porto as well as the entire area within the caldera surrounding the cone. The less frequent surge eruptions on Lipari have been even more violent. The extreme mobility of surges like those produced from Monte Guardia (approx. 20,000 y.b.p.) and Monte Pilato would not only threaten the entire island of Lipari, but also the northern part of neighboring Vulcano. Eruptions at Vesuvius with energy and efficiency similar to that of the May 18, 1980 blast of Mount St. Helens would be still more destructive because of the great initial elevation of the summit vent. In addition, surge eruptions at Vesuvius are generally part of more complex eruption cycles that involve several other types of volcanic phenomena including Plinian fall and pyroclastic flows.

  8. 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

  9. The preliminary results: Internal seismic velocity structure imaging beneath Mount Lokon

    SciTech Connect

    Firmansyah, Rizky, E-mail: rizkyfirmansyah@hotmail.com; Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id; Kristianto, E-mail: kris@vsi.esdm.go.id

    2015-04-24

    Historical records that before the 17{sup th} century, Mount Lokon had been dormant for approximately 400 years. In the years between 1350 and 1400, eruption ever recorded in Empung, came from Mount Lokon’s central crater. Subsequently, in 1750 to 1800, Mount Lokon continued to erupt again and caused soil damage and fall victim. After 1949, Mount Lokon dramatically increased in its frequency: the eruption interval varies between 1 – 5 years, with an average interval of 3 years and a rest interval ranged from 8 – 64 years. Then, on June 26{sup th}, 2011, standby alert set by the Centermore » for Volcanology and Geological Hazard Mitigation. Peak activity happened on July 4{sup th}, 2011 that Mount Lokon erupted continuously until August 28{sup th}, 2011. In this study, we carefully analyzed micro-earthquakes waveform and determined hypocenter location of those events. We then conducted travel time seismic tomographic inversion using SIMULPS12 method to detemine Vp, Vs and Vp/Vs ratio structures beneath Lokon volcano in order to enhance our subsurface geological structure. During the tomographic inversion, we started from 1-D seismic velocities model obtained from VELEST33 method. Our preliminary results show low Vp, low Vs, and high Vp/Vs are observed beneath Mount Lokon-Empung which are may be associated with weak zone or hot material zones. However, in this study we used few station for recording of micro-earthquake events. So, we suggest in the future tomography study, the adding of some seismometers in order to improve ray coverage in the region is profoundly justified.« less

  10. Catalog of Mount St. Helens 2004-2007 Dome Samples with Major- and Trace-Element Chemistry

    USGS Publications Warehouse

    Thornber, Carl R.; Pallister, John S.; Rowe, Michael C.; McConnell, Siobhan; Herriott, Trystan M.; Eckberg, Alison; Stokes, Winston C.; Cornelius, Diane Johnson; Conrey, Richard M.; Hannah, Tammy; Taggart, Joseph E.; Adams, Monique; Lamothe, Paul J.; Budahn, James R.; Knaack, Charles M.

    2008-01-01

    Sampling and analysis of eruptive products at Mount St. Helens is an integral part of volcano monitoring efforts conducted by the U.S. Geological Survey?s Cascades Volcano Observatory (CVO). The objective of our eruption sampling program is to enable petrological assessments of pre-eruptive magmatic conditions, critical for ascertaining mechanisms for eruption triggering and forecasting potential changes in eruption behavior. This report provides a catalog of near-vent lithic debris and new dome-lava collected during 34 intra-crater sampling forays throughout the October 2004 to October 2007 (2004?7) eruptive interval at Mount St. Helens. In addition, we present comprehensive bulk-rock geochemistry for a time-series of representative (2004?7) eruption products. This data, along with that in a companion report on Mount St. Helens 2004 to 2006 tephra by Rowe and others (2008), are presented in support of the contents of the U.S. Geological Survey Professional Paper 1750 (Sherrod and others, eds., 2008). Readers are referred to appropriate chapters in USGS Professional Paper 1750 for detailed narratives of eruptive activity during this time period and for interpretations of sample characteristics and geochemical data. The suite of rock samples related to the 2004?7 eruption of Mount St. Helens and presented in this catalog are archived at the David A. Johnson Cascades Volcano Observatory, Vancouver, Wash. The Mount St. Helens 2004?7 Dome Sample Catalogue with major- and trace-element geochemistry is tabulated in 3 worksheets of the accompanying Microsoft Excel file, of2008-1130.xls. Table 1 provides location and sampling information. Table 2 presents sample descriptions. In table 3, bulk-rock major and trace-element geochemistry is listed for 44 eruption-related samples with intra-laboratory replicate analyses of 19 dacite lava samples. A brief overview of the collection methods and lithology of dome samples is given below as an aid to deciphering the dome sample

  11. Magma Intrusion at Mount St. Helens, Washington, from Temporal Gravity Variations

    NASA Astrophysics Data System (ADS)

    Battaglia, Maurizio; Lisowski, Mike; Dzursin, Dan; Poland, Mike; Schilling, Steve; Diefenbach, Angie; Wynn, Jeff

    2017-04-01

    Mount St. Helens is a stratovolcano in the Pacific Northwest region of the United States, best known for its explosive eruption in May 1980 - deadliest and most economically destructive volcanic event in US history. Volcanic activity renewed in September 2004 with a dome forming eruption that lasted until 2008. This eruption was surprising because the preceding four years had seen the fewest earthquakes and no significant deformation since the 1980-86 eruption ended. After the dome forming eruption ended in July 2008, the volcano seismic activity and deformation went back to background values. Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. A high-precision gravity monitoring network (referenced to a base station 36 km NW of the volcano) was set up at Mount St Helens in 2010. Measurements were made at 12 sites on the volcano (at altitudes between 1200 and 2350 m a.s.l.) and 4 sites far afield during the summers of 2010, 2012, and 2014. The repeated gravity measurements revealed an increase in gravity between 2010 and 2014. Positive residual gravity anomalies remained after accounting for changes in surface height, in the Crater Glacier, and in the shallow hydrothermal aquifer. The pattern of residual gravity changes, with a maximum of 57±12 μGal from 2010 to 2014, is radially symmetric and centered on the 2004-08 lava dome. Inversion of the residual gravity signal points to a source 2.5-4 km beneath the crater floor (i.e., in the magma conduit that fed eruptions in 1980-86 and 2004-08). We attribute the gravity increase to re-inflation of the magma plumbing system following the 2004-8 eruption. Recent seismic activity (e.g., the seismic swarm of March 2016) has been interpreted as a response to the slow recharging of the volcano magma chamber.

  12. 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.

  13. Mount Zion Cemetery, 1975 Plot Plan Mount Zion Cemetery/ ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Mount Zion Cemetery, 1975 Plot Plan - Mount Zion Cemetery/ Female Union Band Cemetery, Bounded by 27th Street right-of-way N.W. (formerly Lyons Mill Road), Q Street N.W., & Mill Road N.W., Washington, District of Columbia, DC

  14. Carbon sequestration and eruption hazards

    NASA Astrophysics Data System (ADS)

    Zhang, Y.

    2007-12-01

    In order to reduce the buildup of carbon dioxide in the atmosphere, proposals have been made to sequestrate carbon in ocean, or in coal mines and other underground formations. High gas concentration in ocean or underground formations has to potential to power gas-driven eruptions. In this presentation, possible eruption hazards are explored. Whenever carbon dioxide is sequestrated in the form of carbon dioxide gas, or dissolved and/or absorbed carbon dioxide, it is necessary to exercise caution to avoid gas-driven eruption hazard. It is long known that explosive volcanic eruptions are driven by H2O gas in magma. Lake eruptions powered by dissolved CO2 in lake bottom water were discovered in the 1980's (Kling et al., 1987; Zhang, 1996). Gas-driven ocean eruptions with mechanism similar to lake eruptions have been hypothesized (Zhang, 2003; Zhang and Kling, 2006) although not confirmed. Mud volcanos are commonly thought to be driven by methane-rich fluids in sediment (Milkov, 2000). Recently, Zhang et al. (2007) have proposed that coal outbursts in underground coal mines are driven by dissolved high CO2 concentration in coal, causing coal fragmentation and outburst. That is, coal outbursts may be regarded as a new type of gas-driven eruptions. Therefore, high concentrations of free gas or dissolved/absorbed gas may power eruptions of magma, lake water, ocean water, sediment, and coal. Gas- driven volcanic, lake and ocean eruptions are due to volume expansion from bubble growth, whereas gas-driven coal and sediment eruptions are due to high gas-pressure, leading to fragmentation of coal and sediment. (In explosive volcanism, magma fragmentation is also a critical point.) The threshold conditions for many of these eruptions are not known yet. In planning large (industrial) scale injection of CO2 into a natural reservoir, it is important to know the eruption threshold and design the injection scheme accordingly. More safe sequestration in terms of eruption hazards would

  15. Volcanic eruption plumes on Io

    NASA Technical Reports Server (NTRS)

    Strom, R. G.; Schneider, N. M.

    1982-01-01

    The nine eruption plumes observed by Voyager 1 are discussed. The plumes range in height from about 60 to over 300 km with corresponding ejection velocities of about 0.5 to 1.0 km/s. Plume sources are located on level plains rather than topographic highs and consist of either fissures or calderas. Except for Ple, the brightness distribution monotonically decreases from the core to the top of the plume. Numerous surface deposits similar to those associated with active plumes probably mark the sites of recent eruptions. The distribution of active and recent eruptions appears to be concentrated in the equatorial regions. This suggests that the depositional rate is greater and the surface age younger in the equatorial regions, possibly accounting for the active eruptions suggests that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.

  16. Geologic field trip guide to Mount Mazama and Crater Lake Caldera, Oregon

    USGS Publications Warehouse

    Bacon, Charles R.; Wright, Heather M.

    2017-08-08

    Crater Lake partly fills one of the most spectacular calderas of the world—an 8 by 10 kilometer (km) basin more than 1 km deep formed by collapse of the Mount Mazama volcano during a rapid series of explosive eruptions ~7,700 years ago. Having a maximum depth of 594 meters (m), Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 square kilometers (km2) of pristine forested and alpine terrain, including the lake itself, and virtually all of Mount Mazama. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama’s climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest United States, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. In addition, many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama provide information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive processes revealed by

  17. Speleothems as sensitive recorders of volcanic eruptions - the Bronze Age Minoan eruption recorded in a stalagmite from Turkey

    NASA Astrophysics Data System (ADS)

    Badertscher, S.; Borsato, A.; Frisia, S.; Cheng, H.; Edwards, R. L.; Tüysüz, O.; Fleitmann, D.

    2014-04-01

    Mounting evidence exists that variations in sulphur content in stalagmites are closely linked to changes in volcanic or anthropogenic atmospheric sulphur. The strong dependency of sulphur on soil pH and ecosystem storage, however, can result in a delay of several years to decades in the registration of volcanic eruptions and anthropogenic emissions by stalagmites. Here we present synchrotron-radiation based trace element analysis performed on a precisely-dated section of a stalagmite from Sofular Cave in Northern Turkey. As this section covers the time interval of the intensively studied Minoan volcanic eruption between 1600 and 1650 BC, we can test whether this vigorous eruption can be traced in a stalagmite. Of all measured trace elements, only bromine shows a clear short-lived peak at 1621±25 BC, whereas sulphur and molybdenum show peaks later at 1617±25 and 1589±25 respectively. We suggest that all trace element peaks are related to the Minoan eruption, whereas the observed phasing of bromine, molybdenum and sulphur is related to differences in their retention rates in the soil above Sofular Cave. For the first time, we can show that bromine appears to be an ideal volcanic tracer in stalagmites, as it is a prominent volatile component in volcanic eruptions, can be easily leached in soils and rapidly transferred from the atmosphere through the soil and bedrock into the cave and stalagmite respectively. Highly resolved oxygen and carbon isotope profiles indicate that the Minoan eruption had no detectable climatic and environmental impact in Northern Turkey.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  19. 4D Simulation of Explosive Eruption Dynamics at Vesuvius

    NASA Astrophysics Data System (ADS)

    Neri, A.; Esposti Ongaro, T.; Menconi, G.; de'Michieli Vitturi, M.; Cavazzoni, C.; Erbacci, G.; Baxter, P. J.

    2006-12-01

    We applied, using a supercomputer, a new simulation model based on fundamental transport laws to describe the 4D (3D spatial co-ordinates plus time) multiphase flow dynamics of explosive eruptions. The model solves the fundamental transport equations for a multiphase mixture formed by a continuous multi-component gas phase and n solid particulate phases representative of magma fragments (such as ash, crystals, and lapilli). Numerical simulations describe the collapse of the volcanic eruption column and the propagation of pyroclastic density currents, for selected medium scale (sub-Plinian) eruptive scenarios at Vesuvius, Italy. The study shows that 4D multiphase numerical models can illuminate the non-intuitive and internal dynamics of explosive eruptions that cannot otherwise be studied by direct observation or using previous models. In particular, simulations provide crucial insights into the effects of the generation mechanism of the flows - partial collapse vs boiling-over - on their hazard potential, the complex dynamics of the collapsing column, and the influence of Mount Somma on the propagation of PDCs into the circum-Vesuvian area, one of the world's most hazardous volcanic settings.

  20. Impact of major volcanic eruptions on stratospheric water vapour

    NASA Astrophysics Data System (ADS)

    Löffler, M.; Brinkop, S.; Jöckel, P.

    2015-12-01

    Volcanic eruptions can have significant impact on the earth's weather and climate system. Besides the subsequent tropospheric changes also the stratosphere is influenced by large eruptions. Here changes in stratospheric water vapour after the two major volcanic eruptions of El Chichón in Mexico in 1982 and Mount Pinatubo on the Philippines in 1991 are investigated with chemistry-climate model simulations. This study is based on two simulations with specified dynamics of the EMAC model, performed within the Earth System Chemistry integrated Modelling (ESCiMo) project, of which only one includes the volcanic forcing through prescribed aerosol optical properties. The results show a significant increase in stratospheric water vapour after the eruptions, resulting from increased heating rates and the subsequent changes in stratospheric and tropopause temperatures in the tropics. The tropical vertical advection and the South Asian summer monsoon are identified as important sources for the additional water vapour in the stratosphere. Additionally, volcanic influences on the tropospheric water vapour and ENSO are evident.

  1. 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

  2. Eruption at Bardarbunga, Iceland

    NASA Image and Video Library

    2015-01-27

    The main caldera of Bardarbunga volcano is tucked beneath Iceland’s largest glacier, Vatnajökull. Beginning in August, 2014, red-hot basaltic lava originating from Bardarbunga has been pouring from fissures just north of Vatnajökull, creating the massive Holuhraun lava field. As of January 6, 2015, the Holuhraun lava field had spread across more than 84 square kilometers (32 square miles), making it larger than the island of Manhattan. Holuhraun is Iceland’s largest basaltic lava flow since the Laki eruption in 1783–84, an event that killed 20 percent of the island’s population. Scientists from the University of Iceland’s Institute of Earth Sciences have estimated the thickness of the lava field based on data from surveillance flights. On average, the eastern part was about 10 meters (33 feet) thick, the center was 12 meters, and the western part was 14 meters. Their preliminary analysis put the volume of lava at 1.1 cubic kilometers, enough for the eruption to be considered a flood basalt. While Holuhraun continues to spew copious amounts of lava and sulfur dioxide, some observations suggest the eruption may be slowing down. As Edinburgh University volcanologist John Stevenson noted on his blog, Icelandic scientists have shown that the sinking (subsidence) of the caldera has declined from 80 centimeters (31 inches) to 25 centimeters per day—a sign that less magma is moving toward the surface. In addition, magnitude 5 or higher earthquakes that used to occur daily are now happening about once a week. Meanwhile, satellite observations of heat flux show a decline from more than 20 gigawatts in early September to fewer than 5 gigawatts by the end of November. As reported by Volcano Discovery, one bold scientist has even suggested that it is reasonable to forecast that the eruption may be over by March, 2015. The Moderate Resolution Imaging Spectrometer (MODIS) aboard NASA’s Aqua satellite flew over Iceland on January 18, 2015 and captured a false

  3. Map of Lower Mount Sharp

    NASA Image and Video Library

    2014-09-11

    This is a map of lower Mount Sharp on Mars, showing the major geologic units identified from orbit. The rocks of the Murray Formation, mapped in green, likely represent the oldest layers of Mount Sharp that NASA Curiosity rover will explore.

  4. 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.

  5. Role of syn-eruptive plagioclase disequilibrium crystallization in basaltic magma ascent dynamics

    PubMed Central

    La Spina, G.; Burton, M.; de' Michieli Vitturi, M.; Arzilli, F.

    2016-01-01

    Timescales of magma ascent in conduit models are typically assumed to be much longer than crystallization and gas exsolution for basaltic eruptions. However, it is now recognized that basaltic magmas may rise fast enough for disequilibrium processes to play a key role on the ascent dynamics. The quantification of the characteristic times for crystallization and exsolution processes are fundamental to our understanding of such disequilibria and ascent dynamics. Here we use observations from Mount Etna's 2001 eruption and a magma ascent model to constrain timescales for crystallization and exsolution processes. Our results show that plagioclase reaches equilibrium in 1–2 h, whereas ascent times were <1 h. Using these new constraints on disequilibrium plagioclase crystallization we also reproduce observed crystal abundances for different basaltic eruptions. The strong relation between magma ascent rate and disequilibrium crystallization and exsolution plays a key role in controlling eruption dynamics in basaltic volcanism. PMID:27941750

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Prehistoric eruptions are generally treated as discrete events, separated from preceding and following events by periods defined by 14C or radiometric dating as centuries or longer. Modern events such as Monserrat (1995-?) or Mount St. Helens (1980-86; 2004-2008) blur this distinction with 'eruption episodes' versus 'separate eruptions' becoming a semantic issue. For rhyolite eruptions, where historic events are scarce, discerning episodicity within, or close spacing between, eruptions becomes important. Time gaps of a few decades or less are challenging to recognise and quantify in eruption products, but important in terms of modelling future events and considering the consequent hazards, economic impacts and associated societal responses. We here consider the geological record for the timing of prehistoric rhyolite eruptions over a range of sizes. In some, such as the Bishop Tuff, there is no evidence in the eruptive stratigraphy to suggest any significant hiat