The active submarine NW termination of the South Aegean Active Volcanic Arc: The Submarine Pausanias Volcanic Field

NASA Astrophysics Data System (ADS)

Foutrakis, Panagiotis M.; Anastasakis, George

2018-05-01

Methana peninsula shows the longest recorded volcanic history at the western end of the South Aegean Active Volcanic Arc, including volcanic products from the Upper Pliocene to recent times. The volcanic rocks comprise widespread dacite domes and andesite lava flows from several small volcanic centers and are only imprecisely dated. In this paper, the integrated analysis of swath bathymetry, side scan sonar data, and high resolution seismic reflection profiles correlated with core samples, has allowed detailed mapping, characterization and precise chronological identification of the Pausanias submarine volcanic field activity offshore northern Methana. Six volcanic cones or domes are recognized, typically 1-3 km in diameter, some elongated NE-SW and some with a small central crater. On their flanks, the acoustically reflective volcanic rocks pass laterally into incoherent transparent seismic facies interpreted as volcaniclastic deposits, possibly including hyaloclastites, that interfinger with the regional basin sediments. A sea-bottom hummocky field, is interpreted as volcanic avalanche and appears to be the submarine continuation of the volcaniclastic apron of northern Methana peninsula. A robust chronostratigraphic framework has been established, based on the recognition of shoreline progradational units and their connection with Quaternary eustatic sea level cycles. Relative dating of the different phases of submarine volcanic activity during the Upper Quaternary has been achieved by correlating the imaged volcaniclastic flows, interlayered within the chronostratigraphically dated sediments. Dating by stratigraphic position, relative to 2D imaged eustatic sea level clinoform wedges appears to be more precise than radiometric methods on land. Three main submarine Volcanic Events (VE) are recognized: VE3 at 450 ka, a less precisely dated interval at 200-130 ka (VE2), and VE1 at 14 ka. Based on chronostratigraphic constraints, subsidence rates of 0.16 (±0.008) m

Using Volcanic Lightning Measurements to Discern Variations in Explosive Volcanic Activity

NASA Astrophysics Data System (ADS)

Behnke, S. A.; Thomas, R. J.; McNutt, S. R.; Edens, H. E.; Krehbiel, P. R.; Rison, W.

2013-12-01

VHF observations of volcanic lightning have been made during the recent eruptions of Augustine Volcano (2006, Alaska, USA), Redoubt Volcano (2009, Alaska, USA), and Eyjafjallajökull (2010, Iceland). These show that electrical activity occurs both on small scales at the vent of the volcano, concurrent with an eruptive event and on large scales throughout the eruption column during and subsequent to an eruptive event. The small-scale discharges at the vent of the volcano are often referred to as 'vent discharges' and are on the order of 10-100 meters in length and occur at rates on the order of 1000 per second. The high rate of vent discharges produces a distinct VHF signature that is sometimes referred to as 'continuous RF' radiation. VHF radiation from vent discharges has been observed at sensors placed as far as 100 km from the volcano. VHF and infrasound measurements have shown that vent discharges occur simultaneously with the onset of eruption, making their detection an unambiguous indicator of explosive volcanic activity. The fact that vent discharges are observed concurrent with explosive volcanic activity indicates that volcanic ejecta are charged upon eruption. VHF observations have shown that the intensity of vent discharges varies between eruptive events, suggesting that fluctuations in eruptive processes affect the electrification processes giving rise to vent discharges. These fluctuations may be variations in eruptive vigor or variations in the type of eruption; however, the data obtained so far do not show a clear relationship between eruption parameters and the intensity or occurrence of vent discharges. Further study is needed to clarify the link between vent discharges and eruptive behavior, such as more detailed lightning observations concurrent with tephra measurements and other measures of eruptive strength. Observations of vent discharges, and volcanic lightning observations in general, are a valuable tool for volcano monitoring, providing a

On volcanism and thermal tectonics on one-plate planets

NASA Technical Reports Server (NTRS)

Solomon, S. C.

1978-01-01

For planets with a single global lithospheric shell or 'plate', the thermal evolution of the interior affects the surface geologic history through volumetric expansion and the resultant thermal stress. Interior warming of such planets gives rise to extensional tectonics and a lithospheric stress system conductive to widespread volcanism. Interior cooling leads to compressional tectonics and lithospheric stresses that act to shut off surface volcanism. On the basis of observed surface tectonics, it is concluded that the age of peak planetary volume, the degree of early heating, and the age of youngest major volcanism on the one-plate terrestrial planets likely decrease in the order Mercury, Moon, Mars.

A field trip guide to the petrology of Quaternary volcanism on the Yellowstone Plateau

USGS Publications Warehouse

Vazquez, Jorge A.; Stelten, Mark; Bindeman, Ilya N.; Cooper, Kari

2017-12-19

The Yellowstone Plateau is one of the largest manifestations of silicic volcanism on Earth, and marks the youngest focus of magmatism associated with the Yellowstone Hot Spot. The earliest products of Yellowstone Hot Spot volcanism are from ~17 million years ago, but may be as old as ~32 Ma, and include contemporaneous eruption of voluminous mafic and silicic magmas, which are mostly located in the region of northwestern Nevada and southeastern Oregon. Since 17 Ma, the main locus of Yellowstone Hot Spot volcanism has migrated northeastward producing numerous silicic caldera complexes that generally remain active for ~2–4 million years, with the present-day focus being the Yellowstone Plateau. Northeastward migration of volcanism associated with the Yellowstone Hot Spot resulted in the formation of the Snake River Plain, a low relief physiographic feature extending ~750 kilometers from northern Nevada to eastern Idaho. Most of the silicic volcanic centers along the Snake River Plain have been inundated by younger basalt volcanism, but many of their ignimbrites and lava flows are exposed in the extended regions at the margins of the Snake River Plain. 

Long-term volcanic hazard assessment on El Hierro (Canary Islands)

NASA Astrophysics Data System (ADS)

Becerril, L.; Bartolini, S.; Sobradelo, R.; Martí, J.; Morales, J. M.; Galindo, I.

2014-07-01

Long-term hazard assessment, one of the bastions of risk-mitigation programs, is required for land-use planning and for developing emergency plans. To ensure quality and representative results, long-term volcanic hazard assessment requires several sequential steps to be completed, which include the compilation of geological and volcanological information, the characterisation of past eruptions, spatial and temporal probabilistic studies, and the simulation of different eruptive scenarios. Despite being a densely populated active volcanic region that receives millions of visitors per year, no systematic hazard assessment has ever been conducted on the Canary Islands. In this paper we focus our attention on El Hierro, the youngest of the Canary Islands and the most recently affected by an eruption. We analyse the past eruptive activity to determine the spatial and temporal probability, and likely style of a future eruption on the island, i.e. the where, when and how. By studying the past eruptive behaviour of the island and assuming that future eruptive patterns will be similar, we aim to identify the most likely volcanic scenarios and corresponding hazards, which include lava flows, pyroclastic fallout and pyroclastic density currents (PDCs). Finally, we estimate their probability of occurrence. The end result, through the combination of the most probable scenarios (lava flows, pyroclastic density currents and ashfall), is the first qualitative integrated volcanic hazard map of the island.

Morphological Analysis of Apo Volcanic Complex in Southern Mindanao, Philippines: implications on volcano-tectonic evolution of different volcanic units

NASA Astrophysics Data System (ADS)

Herrero, T. M. L.; van Wyk de Vries, B.; Lagmay, A. M. A.; Eco, R. C.

2015-12-01

The Apo Volcanic Complex (AVC) is one of the largest volcanic centers in the Philippines, located in the southern island of Mindanao. It is composed of four edifices and several smaller cones. The youngest volcanic unit, the Apo Dome, is the highest elevation in the Philippines. This unit is classified as potentially active, whereas other units, Talomo, Sibulan and Kitubod, are inactive. The study gives insight to the construction and deformation history of the volcanic units and imparts foresight to subsequent events that can affect populated areas. A morphological analysis integrating high-resolution digital terrain models and public domain satellite data and images was done to recognize and discriminate volcanic units and characterize volcano-tectonic features and processes. Morphological domains were defined based on surface textures, slope variation, degrees and controls of erosion, and lineament density and direction. This establishes the relative ages and extent of volcanic units as well as the volcano-tectonic evolution of the complex. Six edifice building events were recognized, two of which form the elevated base of Apo dome. The geodynamic setting of the region is imprinted in the volcanic units as five morphostructural lineaments. They reveal the changes in maximum regional stress through time such as the N-S extension found across the whole volcanic complex displaying the current stress regime. This has implications on the locality and propagation of geothermal activity, magma ascent, and edifice collapses. One main result of the compounded effects of inherited structures and current stress regime is the Sandawa Collapse Zone. This is a large valley formed by several collapses where NE-SW fractures propagate and the increasing lateral spreading by debuttressing continue to eat away the highest peak. The AVC is surrounded by the major metropolitan area of Davao City to the east and the cities of Kidapawan and Digos to the west and south, respectively

The Physical and Petrologic Evolution of a Multi-vent Volcanic Field Associated With Yellowstone-Newberry Volcanism

NASA Astrophysics Data System (ADS)

Brueseke, M. E.; Hart, W. K.

2004-12-01

The Santa Rosa-Calico volcanic field (SC) of northern Nevada is perhaps the most chemically and physically diverse of all volcanic fields associated with mid-Miocene northwestern USA volcanism. SC volcanism occurred from 16.5 to 14 Ma and was characterized by the eruption of a complete compositional spectrum from basalt through high-Si rhyolite. Locally derived tholeiitic lava flows and shallow intrusive bodies are chemically and isotopically identical to the Steens Basalt (87/86Sri=<0.7040), the Oregon Plateau-wide mid-Miocene flood basalt. Andesite-dacite lava flows are exposed as at least four geographically and chemically distinct packages representing products of multiple, discrete magmatic systems. The most voluminous of these is calc-alkaline and characterized by abundant granitoid and mafic xenoliths/xenocrysts and radiogenic Sr isotopic ratios. Subalkaline silicic lava flows, domes, and shallow intrusive bodies define three diffuse north-south trending zones. Textural, chemical, and isotopic variability within the silicic units is linked to their spatial and temporal distribution, again necessitating the existence of multiple magmatic systems. The youngest locally derived silicic units are ash flows exposed in the central portion of the SC that erupted in actively forming sedimentary basins at ˜15.4 Ma. Underlying the 400-1500m thick package of SC volcanic rocks are temporally ( ˜103 and ˜85 Ma), chemically, and isotopically (87/86Sr at 16 Ma= 0.7045 to 0.7058 and 0.7061 to >0.7070) heterogeneous granitoid plutons and a package of ˜20-23 Ma calc-alkaline, arc-related intermediate lava flows. The observed disequilibrium textures, xenoliths, and chemical/isotopic diversity suggests that upwelling Steens magma interacted with local crust, siliceous crustal melts, and the mafic plutonic roots of early Miocene arc volcanism in multiple magmatic systems characterized by heterogeneous open system processes. The formation of these systems is tectonically

The youngest silicic eruptions from the Valles Caldera and volcanic hazard potential in north-central New Mexico

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

WoldeGabriel, Giday; Kelley, Richard E.; Miller, Elizabeth D.

Here, sporadic mafic and felsic eruptions, representing at least five major and several smaller pulses of effusive and explosive volcanic products that range in age from 25.5 Ma to 68.3 ka, crop out within the Jemez volcanic field and the surrounding areas in north central New Mexico.

The youngest silicic eruptions from the Valles Caldera and volcanic hazard potential in north-central New Mexico

DOE PAGES

WoldeGabriel, Giday; Kelley, Richard E.; Miller, Elizabeth D.; ...

2016-05-01

Here, sporadic mafic and felsic eruptions, representing at least five major and several smaller pulses of effusive and explosive volcanic products that range in age from 25.5 Ma to 68.3 ka, crop out within the Jemez volcanic field and the surrounding areas in north central New Mexico.

Status of volcanism studies for the Yucca Mountain Site Characterization Project

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

Crowe, B.; Perry, F.; Murrell, M.

1995-02-01

Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The Lathrop Wells volcanic center is described in detailmore » because it is the youngest basalt center in the YMR. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. Geophysical data are described for the YMR and are used as an aid to understand the distribution of basaltic volcanic centers. Chapter 4 discusses the petrologic and geochemical features of basaltic volcanism in the YMR, the southern Great Basin and the Basin and Range province. The long time of activity and characteristic small volume of the Postcaldera basalt of the YMR result in one of the lowest eruptive rates in a volcanic field in the southwest United States. Chapter 5 summarizes current concepts of the segregation, ascent, and eruption of basalt magma. Chapter 6 summarizes the history of volcanism studies (1979 through early 1994), including work for the Yucca Mountain Site Characterization Project and overview studies by the state of Nevada and the Nuclear Regulatory Commission. Chapter 7 summarizes probabilistic volcanic hazard assessment using a three-part conditional probability model. Chapter 8 describes remaining volcanism work judged to be needed to complete characterization studies for the YMR. Chapter 9 summarizes the conclusions of this volcanism status report.« less

Lunar farside volcanism in and around the South Pole-Aitken basin

NASA Astrophysics Data System (ADS)

Pasckert, Jan Hendrik; Hiesinger, Harald; van der Bogert, Carolyn H.

2018-01-01

We identified and mapped 129 mare basalt deposits in and around the South Pole-Aitken (SPA) basin, and determined absolute model ages (AMAs) for 101 of these units by performing crater size-frequency distribution (CSFD) measurements. The derived AMAs range from 2.2 Ga to 3.7 Ga, with the youngest deposits within Antoniadi crater and the oldest deposits at Jules Verne crater. Our investigations indicate a major peak in volcanic activity between 3.6 Ga and 3.2 Ga, which is a similar time range as the major volcanic activity on the nearside, and the rest of the farside. However, a second peak in volcanic activity (2.2-2.5 Ga), as observed for the nearside and parts of the farside, is not observed for the mare deposits within the SPA basin. Combining all AMAs derived for farside mare basalts reveals that volcanic activity was more abundant and lasted longer on the nearside than on the farside. We propose that the stripping of insulating crust by the large SPA-forming impact event, in combination with lower amounts of heat producing elements like Th, might be responsible for the reduced volcanic activity in the SPA basin. In addition, we estimated the thicknesses and volumes of the investigated mare deposits. With thicknesses between ∼31 m and ∼273 m and volumes of ∼1 km³ to ∼2630 km³, the mare basalt deposits in and around the SPA basin show a wide range of dimensions, similar to other mare basalts of the near- and farsides. A trend between the AMAs and the estimated volumes was not observed, but the mare deposits within the large northern craters (e.g., Apollo, Ingenii, or Leibnitz) seem to be generally larger and more voluminous than the mare basalt deposits at the center of the SPA basin.

Regional Triggering of Volcanic Activity Following Large Magnitude Earthquakes

NASA Astrophysics Data System (ADS)

Hill-Butler, Charley; Blackett, Matthew; Wright, Robert

2015-04-01

There are numerous reports of a spatial and temporal link between volcanic activity and high magnitude seismic events. In fact, since 1950, all large magnitude earthquakes have been followed by volcanic eruptions in the following year - 1952 Kamchatka M9.2, 1960 Chile M9.5, 1964 Alaska M9.2, 2004 & 2005 Sumatra-Andaman M9.3 & M8.7 and 2011 Japan M9.0. While at a global scale, 56% of all large earthquakes (M≥8.0) in the 21st century were followed by increases in thermal activity. The most significant change in volcanic activity occurred between December 2004 and April 2005 following the M9.1 December 2004 earthquake after which new eruptions were detected at 10 volcanoes and global volcanic flux doubled over 52 days (Hill-Butler et al. 2014). The ability to determine a volcano's activity or 'response', however, has resulted in a number of disparities with <50% of all volcanoes being monitored by ground-based instruments. The advent of satellite remote sensing for volcanology has, therefore, provided researchers with an opportunity to quantify the timing, magnitude and character of volcanic events. Using data acquired from the MODVOLC algorithm, this research examines a globally comparable database of satellite-derived radiant flux alongside USGS NEIC data to identify changes in volcanic activity following an earthquake, February 2000 - December 2012. Using an estimate of background temperature obtained from the MODIS Land Surface Temperature (LST) product (Wright et al. 2014), thermal radiance was converted to radiant flux following the method of Kaufman et al. (1998). The resulting heat flux inventory was then compared to all seismic events (M≥6.0) within 1000 km of each volcano to evaluate if changes in volcanic heat flux correlate with regional earthquakes. This presentation will first identify relationships at the temporal and spatial scale, more complex relationships obtained by machine learning algorithms will then be examined to establish favourable

The temporal variation of Mesoarchaean volcanism in the Suomussalmi greenstone belt, Karelia Province, Eastern Finland

NASA Astrophysics Data System (ADS)

Lehtonen, E.; Heilimo, E.; Halkoaho, T.; Hölttä, P.; Huhma, H.

2017-03-01

This study concentrates in the Kiannanniemi area, situated in the Archaean Suomussalmi greenstone belt, the Karelia Province, Fennoscandian Shield. A zircon U-Pb geochronological study from this area shows that ages of the volcanic rocks are between ca. 2.94 and 2.82 Ga. The results indicate multiphase felsic and intermediate volcanism in three episodes at ca. 2.94, 2.84 and 2.82 Ga, of which the 2.84 Ga event has not been reported earlier from the Suomussalmi greenstone belt. The youngest zircon population in a sedimentary rock sample suggests a depositional age of ≤2.82-2.81 Ga, and the sample contains also ≥2.96 Ga old zircon grains. Based on both new and previously published geochronological data from the volcanic rocks, we propose a chronostratigraphic model for the whole Suomussalmi greenstone belt, dividing it into four units based on their age: Luoma, Tormua, Ahvenlahti, and Mesa-aho. The youngest volcanic rocks in the Suomussalmi greenstone belt are contemporaneous with some of the volcanic rocks recorded from the Kuhmo and Tipasjärvi greenstone belts of the Karelia Province, Finland. The age group ca. 2.94 Ga, however, has not been so far recorded elsewhere. Conversely, in the Suomussalmi greenstone belt, volcanic rocks with an age of ca. 2.80 Ga and sedimentary rocks with depositional ages of <2.75 Ga, frequently found from the Kuhmo and Tipasjärvi greenstone belts, are unknown.

Gish Bar Patera, Io: Geology and Volcanic Activity, 1996-2001

NASA Technical Reports Server (NTRS)

Perry, Jason; Radebaugh, Jani; Lopes, Rosaly; McEwen, Alfred; Keszthelyi, Laszlo

2003-01-01

Since the two Voyagers passed by Jupiter in 1979, it has been known that volcanic activity is ubiquitous on the surface of Io. With over 400 volcanic centers, Io is even more volcanically active than the earth with massive flood basalt-style eruptions and komatitite lavas a common occurrence. Additionally, some volcanoes appear to be giant lava lakes, with violent activity churning the crust of the lake for periods of 20 years or more. Finally, sulfur is believed to play a large role in Io's volcanism, be it as a primary lava or as a secondary product of large, high-temperature eruptions. By studying one volcano in particular, Gish Bar Patera, one can observe many of these characteristics in one volcanic center.

Evidence for young volcanism on Mercury from the third MESSENGER flyby.

PubMed

Prockter, Louise M; Ernst, Carolyn M; Denevi, Brett W; Chapman, Clark R; Head, James W; Fassett, Caleb I; Merline, William J; Solomon, Sean C; Watters, Thomas R; Strom, Robert G; Cremonese, Gabriele; Marchi, Simone; Massironi, Matteo

2010-08-06

During its first two flybys of Mercury, the MESSENGER spacecraft acquired images confirming that pervasive volcanism occurred early in the planet's history. MESSENGER's third Mercury flyby revealed a 290-kilometer-diameter peak-ring impact basin, among the youngest basins yet seen, having an inner floor filled with spectrally distinct smooth plains. These plains are sparsely cratered, postdate the formation of the basin, apparently formed from material that once flowed across the surface, and are therefore interpreted to be volcanic in origin. An irregular depression surrounded by a halo of bright deposits northeast of the basin marks a candidate explosive volcanic vent larger than any previously identified on Mercury. Volcanism on the planet thus spanned a considerable duration, perhaps extending well into the second half of solar system history.

The relationship between eruptive activity, flank collapse, and sea level at volcanic islands: A long-term (>1 Ma) record offshore Montserrat, Lesser Antilles

NASA Astrophysics Data System (ADS)

Coussens, Maya; Wall-Palmer, Deborah; Talling, Peter. J.; Watt, Sebastian. F. L.; Cassidy, Michael; Jutzeler, Martin; Clare, Michael A.; Hunt, James. E.; Manga, Michael; Gernon, Thomas. M.; Palmer, Martin. R.; Hatter, Stuart. J.; Boudon, Georges; Endo, Daisuke; Fujinawa, Akihiko; Hatfield, Robert; Hornbach, Matthew. J.; Ishizuka, Osamu; Kataoka, Kyoko; Le Friant, Anne; Maeno, Fukashi; McCanta, Molly; Stinton, Adam. J.

2016-07-01

Hole U1395B, drilled southeast of Montserrat during Integrated Ocean Drilling Program Expedition 340, provides a long (>1 Ma) and detailed record of eruptive and mass-wasting events (>130 discrete events). This record can be used to explore the temporal evolution in volcanic activity and landslides at an arc volcano. Analysis of tephra fall and volcaniclastic turbidite deposits in the drill cores reveals three heightened periods of volcanic activity on the island of Montserrat (˜930 to ˜900 ka, ˜810 to ˜760 ka, and ˜190 to ˜120 ka) that coincide with periods of increased volcano instability and mass-wasting. The youngest of these periods marks the peak in activity at the Soufrière Hills volcano. The largest flank collapse of this volcano (˜130 ka) occurred toward the end of this period, and two younger landslides also occurred during a period of relatively elevated volcanism. These three landslides represent the only large (>0.3 km3) flank collapses of the Soufrière Hills edifice, and their timing also coincides with periods of rapid sea level rise (>5 m/ka). Available age data from other island arc volcanoes suggest a general correlation between the timing of large landslides and periods of rapid sea level rise, but this is not observed for volcanoes in intraplate ocean settings. We thus infer that rapid sea level rise may modulate the timing of collapse at island arc volcanoes, but not in larger ocean-island settings.

SHARAD Investigation of the Interaction Between Volcanism and Deep Water Release in Elysium Planitia, Mars

NASA Astrophysics Data System (ADS)

Morgan, G. A.; Campbell, B. A.; Carter, L. M.; Plaut, J. J.

2011-12-01

Situated between the equator and 12°N and extending from 130° to 180°E, Elysium Planitia is considered to be the youngest volcanic plain on Mars. Recent crater counts on individual lava units argue for multiple phases of activity over the last 230 Myrs, with the most recent volcanic features dating to just ~2 Ma. The region also contains the youngest outflow channels on the planet. Multiple channel systems which are present across the region are interpreted to have been carved by the release of deep ground water (>1 km) from the broadly east-west trending Cerberus Fossae graben system. Elysium Planitia is therefore a region of high scientific interest, as it represents an ideal site to investigate the interaction of lava and water both below and on the surface of Mars. Extensive geologic mapping of Elysium Planitia has provided detailed information concerning the stratigraphy of the major volcanic units in addition to the classification of other landforms attributed to volcanic (e.g. small shields), fluvial (e.g. outflow channels) and aeolian (e.g. yardangs) activity. Orbital sounding radar provides a means to take this work to the next level through the mapping of buried surfaces associated with a contrast in dielectric permittivity and thus can be used to investigate the 3-D structure of the subsurface. Previous studies using the SHARAD radar sounder onboard the Mars Reconnaissance Orbiter have identified multiple subsurface reflectors below the plains of Elysium Planitia. We will present our investigation of SHARAD data covering the eastern portion of this region of Mars - an area that includes the upstream reaches of Marte Vallis and the eastern extent of Cerberus Fossae. Our subsurface mapping shows remarkable correlations with published geologic maps produced using visible orbital datasets. These similarities allow us to use SHARAD data to make estimates of the average permittivity values and imply density measurements of the volcanic units. We will

Volcanic activity: a review for health professionals.

PubMed Central

Newhall, C G; Fruchter, J S

1986-01-01

Volcanoes erupt magma (molten rock containing variable amounts of solid crystals, dissolved volatiles, and gas bubbles) along with pulverized pre-existing rock (ripped from the walls of the vent and conduit). The resulting volcanic rocks vary in their physical and chemical characteristics, e.g., degree of fragmentation, sizes and shapes of fragments, minerals present, ratio of crystals to glass, and major and trace elements composition. Variability in the properties of magma, and in the relative roles of magmatic volatiles and groundwater in driving an eruption, determine to a great extent the type of an eruption; variability in the type of an eruption in turn influences the physical characteristics and distribution of the eruption products. The principal volcanic hazards are: ash and larger fragments that rain down from an explosion cloud (airfall tephra and ballistic fragments); flows of hot ash, blocks, and gases down the slopes of a volcano (pyroclastic flows); "mudflows" (debris flows); lava flows; and concentrations of volcanic gases in topographic depressions. Progress in volcanology is bringing improved long- and short-range forecasts of volcanic activity, and thus more options for mitigation of hazards. Collaboration between health professionals and volcanologists helps to mitigate health hazards of volcanic activity. Images FIGURE 1 FIGURE 2 FIGURE 6a-6e FIGURE 6a-6e FIGURE 8 FIGURE 9 FIGURE 10 FIGURE 11 PMID:3946726

Paleomagnetic investigation of some volcanic rocks from the McMurdo volcanic province, Antarctica

USGS Publications Warehouse

Mankinen, E.A.; Cox, A.

1988-01-01

Paleomagnetic data for lava flows from sporadic but long-lived eruptions in the McMurdo Sound region are combined with previously published geologic and geochronologic data to determine the general eruptive sequence of the area. Lava flows in the Walcott Bay area were erupted during the Gauss Normal, Matuyama Reversed, and Brunhes Normal Polarity Chrons. The youngest flows on Black Island probably erupted near the boundary between the Gilbert and Gauss chrons. The most recent activity was concentrated on the volcanic edifices of Mounts Morning and Discovery and on Ross Island sampled during this study with those of eight flows that were published previously yields a mean paleomagnetic pole at 87.3??N, 317.3??E (??95 = 6.3??). The ancient geomagnetic field dispersion about this mean pole is 23.5??, with upper and lower limits of 95% confidence equal to 27.4?? and 20.5??, respectively. This value probably is a reasonable estimate of secular variation for the Antarctic continent during Pliocene and Pleistocene time. -Authors

Integrating Multiple Space Ground Sensors to Track Volcanic Activity

NASA Technical Reports Server (NTRS)

Chien, Steve; Davies, Ashley; Doubleday, Joshua; Tran, Daniel; Jones, Samuel; Kjartansson, Einar; Thorsteinsson, Hrobjartur; Vogfjord, Kristin; Guomundsson, Magnus; Thordarson, Thor;

Tellurium in active volcanic environments: Preliminary results

NASA Astrophysics Data System (ADS)

Milazzo, Silvia; Calabrese, Sergio; D'Alessandro, Walter; Brusca, Lorenzo; Bellomo, Sergio; Parello, Francesco

2014-05-01

Tellurium is a toxic metalloid and, according to the Goldschmidt classification, a chalcophile element. In the last years its commercial importance has considerably increased because of its wide use in solar cells, thermoelectric and electronic devices of the last generation. Despite such large use, scientific knowledge about volcanogenic tellurium is very poor. Few previous authors report result of tellurium concentrations in volcanic plume, among with other trace metals. They recognize this element as volatile, concluding that volcanic gases and sulfur deposits are usually enriched with tellurium. Here, we present some results on tellurium concentrations in volcanic emissions (plume, fumaroles, ash leachates) and in environmental matrices (soils and plants) affected by volcanic emissions and/or deposition. Samples were collected at Etna and Vulcano (Italy), Turrialba (Costa Rica), Miyakejima, Aso, Asama (Japan), Mutnovsky (Kamchatka) at the crater rims by using common filtration techniques for aerosols (polytetrafluoroethylene filters). Filters were both eluted with Millipore water and acid microwave digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Volcanic ashes emitted during explosive events on Etna and Copahue (Argentina) were analyzed for tellurium bulk composition and after leaching experiments to evaluate the soluble fraction of tellurium. Soils and leaves of vegetation were also sampled close to active volcanic vents (Etna, Vulcano, Nisyros, Nyiragongo, Turrialba, Gorely and Masaya) and investigated for tellurium contents. Preliminary results showed very high enrichments of tellurium in volcanic emissions comparing with other volatile elements like mercury, arsenic, thallium and bismuth. This suggests a primary transport in the volatile phase, probably in gaseous form (as also suggested by recent studies) and/or as soluble salts (halides and/or sulfates) adsorbed on the surface of particulate particles and ashes. First

A submarine perspective of the Honolulu Volcanics, Oahu

NASA Astrophysics Data System (ADS)

Clague, David A.; Paduan, Jennifer B.; McIntosh, William C.; Cousens, Brian L.; Davis, Alicé S.; Reynolds, Jennifer R.

2006-03-01

Lavas and volcaniclastic deposits were observed and collected from 4 submarine cones that are part of the Honolulu Volcanics on Oahu, Hawaii. The locations of these and a few additional, but unsampled, vents demonstrate that nearly all the vents are located on or very close to the shoreline of Oahu, with the most distal vent just 12 km offshore. The clastic samples and outcrops range from coarse breccias to cross-bedded ash deposits and show that explosive volcanism at depths between about 350 and 590 m depth played a part in forming these volcanic cones. The eruptive styles appear to be dominantly effusive to strombolian at greater depths, but apparently include violent phreatomagmatic explosive activity at the shallower sites along the submarine southwest extension of the Koko Rift. The compositions of the recovered samples are broadly similar to the strongly alkalic subaerial Honolulu Volcanics lavas, but the submarine lavas, erupted further from the Koolau caldera, have slightly more radiogenic Sr isotopic ratios, and trace element patterns that are distinct from either the subaerial Honolulu Volcanics or the submarine North Arch lavas. These patterns are characterized by moderate to strong positive Sr and P anomalies, and moderate to strong negative Cs, Rb, U, Th, Zr, and Hf anomalies. Most samples have strong negative K and moderate negative Ti anomalies, as do all subaerial Honolulu Volcanics and North Arch samples, but one group of samples from the Koko Rift lack this chemical signature. The data are consistent with more garnet in the source region for the off-shore samples than for either the on-shore Honolulu Volcanics lavas. New Ar-Ar ages show that eruptions at the submarine vents and Diamond Head occurred between about 0.5 Ma and 0.1 Ma, with the youngest ages from the Koko Rift. These ages are in general agreement with most published ages for the formation and suggest that some much younger ages reported previously from the Koko Rift are probably

Active Volcanism on Io as Seen by Galileo SSI

USGS Publications Warehouse

McEwen, A.S.; Keszthelyi, L.; Geissler, P.; Simonelli, D.P.; Carr, M.H.; Johnson, T.V.; Klaasen, K.P.; Breneman, H.H.; Jones, T.J.; Kaufman, J.M.; Magee, K.P.; Senske, D.A.; Belton, M.J.S.; Schubert, G.

1998-01-01

Active volcanism on Io has been monitored during the nominal Galileo satellite tour from mid 1996 through late 1997. The Solid State Imaging (SSI) experiment was able to observe many manifestations of this active volcanism, including (1) changes in the color and albedo of the surface, (2) active airborne plumes, and (3) glowing vents seen in eclipse. About 30 large-scale (tens of kilometers) surface changes are obvious from comparison of the SSI images to those acquired by Voyager in 1979. These include new pyroclastic deposits of several colors, bright and dark flows, and caldera-floor materials. There have also been significant surface changes on Io during the Galileo mission itself, such as a new 400-km-diameter dark pyroclastic deposit around Pillan Patera. While these surface changes are impressive, the number of large-scale changes observed in the four months between the Voyager 1 and Voyager 2 flybys in 1979 suggested that over 17 years the cumulative changes would have been much more impressive. There are two reasons why this was not actually the case. First, it appears that the most widespread plume deposits are ephemeral and seem to disappear within a few years. Second, it appears that a large fraction of the volcanic activity is confined to repeated resurfacing of dark calderas and flow fields that cover only a few percent of Io's surface. The plume monitoring has revealed 10 active plumes, comparable to the 9 plumes observed by Voyager. One of these plumes was visible only in the first orbit and three became active in the later orbits. Only the Prometheus plume has been consistently active and easy to detect. Observations of the Pele plume have been particularly intriguing since it was detected only once by SSI, despite repeated attempts, but has been detected several times by the Hubble Space Telescope at 255 nm. Pele's plume is much taller (460 km) than during Voyager 1 (300 km) and much fainter at visible wavelengths. Prometheus-type plumes (50

Active Volcanism on Io as Seen by Galileo SSI

NASA Astrophysics Data System (ADS)

McEwen, Alfred S.; Keszthelyi, Laszlo; Geissler, Paul; Simonelli, Damon P.; Carr, Michael H.; Johnson, Torrence V.; Klaasen, Kenneth P.; Breneman, H. Herbert; Jones, Todd J.; Kaufman, James M.; Magee, Kari P.; Senske, David A.; Belton, Michael J. S.; Schubert, Gerald

1998-09-01

Active volcanism on Io has been monitored during the nominal Galileo satellite tour from mid 1996 through late 1997. The Solid State Imaging (SSI) experiment was able to observe many manifestations of this active volcanism, including (1) changes in the color and albedo of the surface, (2) active airborne plumes, and (3) glowing vents seen in eclipse. About 30 large-scale (tens of kilometers) surface changes are obvious from comparison of the SSI images to those acquired by Voyager in 1979. These include new pyroclastic deposits of several colors, bright and dark flows, and caldera-floor materials. There have also been significant surface changes on Io during the Galileo mission itself, such as a new 400-km-diameter dark pyroclastic deposit around Pillan Patera. While these surface changes are impressive, the number of large-scale changes observed in the four months between the Voyager 1 and Voyager 2 flybys in 1979 suggested that over 17 years the cumulative changes would have been much more impressive. There are two reasons why this was not actually the case. First, it appears that the most widespread plume deposits are ephemeral and seem to disappear within a few years. Second, it appears that a large fraction of the volcanic activity is confined to repeated resurfacing of dark calderas and flow fields that cover only a few percent of Io's surface. The plume monitoring has revealed 10 active plumes, comparable to the 9 plumes observed by Voyager. One of these plumes was visible only in the first orbit and three became active in the later orbits. Only the Prometheus plume has been consistently active and easy to detect. Observations of the Pele plume have been particularly intriguing since it was detected only once by SSI, despite repeated attempts, but has been detected several times by the Hubble Space Telescope at 255 nm. Pele's plume is much taller (460 km) than during Voyager 1 (300 km) and much fainter at visible wavelengths. Prometheus-type plumes (50

Faults and volcanoes: Main volcanic structures in the Acambay Graben, Mexico

NASA Astrophysics Data System (ADS)

Aguirre-Diaz, G. J.; Pedrazzi, D.; Suñe-Puchol, I.; Lacan, P.

2016-12-01

The Mexican Volcanic Belt (MVB) province is best known by the major stratovolcanoes, such as Popocatepetl and Colima, but most of the province is formed by modest size stratovolcanoes and monogenetic cones. Regional fault systems were developed together with the building of the volcanic province; the most notorious one is Chapala-Tula Fault System (CTFS), which runs parallel to the central sector of the MVB, and thus it is also referred to as the Intra-Arc fault system. Acambay graben (AG) is part of this central system. It is a 20 x 70 km depression located 100 km to the NW of Mexico City, at the easternmost end of the E-W trending CTFS, and was formed as the result of NS to NE oriented extension. Seismically active normal faults, such as the Acambay-Tixmadejé fault, with a mB =7 earthquake in 1912, delimit the AG. The graben includes several volcanic structures and associated deposits ranging in age from Miocene to 3 ka. The main structures are two stratovolcanoes, Altamirano (900 m high) and Temascalcingo (800 m high). There are also several Miocene-Pliocene lava domes, and Quaternary small cinder cones and shield volcanoes. Faulting of the Acambay graben affects all these volcanic forms, but depending on their ages, the volcanoes are cut by several faults or by a few. That is the case of Altamirano and Temascalcingo volcanoes, where the former is almost unaffected whereas the latter is highly dissected by faults. Altamirano is younger than Temascalcingo; youngest pyroclastic deposits from Altamirano are dated at 12-3 ka, and those from Temascalcingo at 40-25 ka (radiocarbon ages). The relatively young ages found in volcanic deposits within the Acambay graben raise the volcanic danger level in this area, originally marked as an inactive volcanic zone, but activity could restart at any time. Supported by DGAPA-PAPIIT-UNAM grant IN-104615.

Volcanic hazards at Atitlan volcano, Guatemala

USGS Publications Warehouse

Haapala, J.M.; Escobar Wolf, R.; Vallance, James W.; Rose, William I.; Griswold, J.P.; Schilling, S.P.; Ewert, J.W.; Mota, M.

2006-01-01

Atitlan Volcano is in the Guatemalan Highlands, along a west-northwest trending chain of volcanoes parallel to the mid-American trench. The volcano perches on the southern rim of the Atitlan caldera, which contains Lake Atitlan. Since the major caldera-forming eruption 85 thousand years ago (ka), three stratovolcanoes--San Pedro, Toliman, and Atitlan--have formed in and around the caldera. Atitlan is the youngest and most active of the three volcanoes. Atitlan Volcano is a composite volcano, with a steep-sided, symmetrical cone comprising alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs. Eruptions of Atitlan began more than 10 ka [1] and, since the arrival of the Spanish in the mid-1400's, eruptions have occurred in six eruptive clusters (1469, 1505, 1579, 1663, 1717, 1826-1856). Owing to its distance from population centers and the limited written record from 200 to 500 years ago, only an incomplete sample of the volcano's behavior is documented prior to the 1800's. The geologic record provides a more complete sample of the volcano's behavior since the 19th century. Geologic and historical data suggest that the intensity and pattern of activity at Atitlan Volcano is similar to that of Fuego Volcano, 44 km to the east, where active eruptions have been observed throughout the historical period. Because of Atitlan's moderately explosive nature and frequency of eruptions, there is a need for local and regional hazard planning and mitigation efforts. Tourism has flourished in the area; economic pressure has pushed agricultural activity higher up the slopes of Atitlan and closer to the source of possible future volcanic activity. This report summarizes the hazards posed by Atitlan Volcano in the event of renewed activity but does not imply that an eruption is imminent. However, the recognition of potential activity will facilitate hazard and emergency preparedness.

Constraints of texture and composition of clinopyroxene phenocrysts of Holocene volcanic rocks on a magmatic plumbing system beneath Tengchong, SW China

NASA Astrophysics Data System (ADS)

Hu, Jun-Hao; Song, Xie-Yan; He, Hai-Long; Zheng, Wen-Qin; Yu, Song-Yue; Chen, Lie-Meng; Lai, Chun-Kit

2018-04-01

Understanding processes of magma replenishment in a magma plumbing system is essential to predict eruption potential of a dormant volcano. In this study, we present new petrologic and thermobarometric data for youngest lava flows from the Holocene Heikongshan volcano in the Tengchong area, SW China. Clinopyroxene phenocrysts from the trachytic lava flows display various textural/compositional zoning styles (i.e., normal, reverse and oscillatory). Such zoning patterns are indicative of an open magmatic plumbing system with multiphase magma replenishment and mixing, which were likely a key drive of the volcanic eruptions. Thermobarometric calculations of these zoned clinopyroxene phenocrysts yield crystallization pressures of 3.8-7.1 kbar (peak at 4.5-7.0 kbar), corresponding to a magma chamber at depths of 14-21 km. The calculated depths are consistent with the large low-resistivity body at 12-30 km beneath the Heikongshan volcano, implying that the magmatic plumbing system may still be active. Recent earthquakes in the Tengchong area suggest that the regional strike-slip faulting are still active, and may trigger future volcanic eruptions if the magma chamber(s) beneath the Tengchong volcanic field is disturbed, in spite of the volcanic quiescence since 1609 CE.

Mapping Intraplate Volcanic Fields: A Case Study from Harrat Rahat, Saudi Arabia

NASA Astrophysics Data System (ADS)

Downs, D. T.; Stelten, M. E.; Champion, D. E.; Dietterich, H. R.

2017-12-01

Continental intraplate mafic volcanoes are typically small-volume (<1 km3), but are one of the most prevalent volcanic landforms on Earth, particularly in the >200 volcanic fields proposed to be active worldwide during the Holocene. Their small individual eruption volumes make any hazards low, however their high prevalence offsets this by raising the risk to populations and infrastructure. The western Arabian Plate hosts at least 15 continental, intra-plate volcanic fields that stretch >3,000 km south to north from Yemen to Turkey. In total, these volcanic fields comprise one of the largest alkali basalt volcanic provinces on Earth, covering an area of 180,000 km2. With a total volume of 20,000 km3, Harrat Rahat in western Saudi Arabia is one of the largest of these volcanic fields. Our study focused on mapping the northern third of the Harrat Rahat volcanic field using a multidisciplinary approach. We have discriminated >200 individual eruptive units, mainly basaltic lava flows throughout Harrat Rahat that are distinguished through a combination of field observations, petrography, geochemistry, paleomagnetism, and 40Ar/39Ar radiometric and 36Cl cosmogenic surface-exposure dating. We have compiled these results into a high-resolution geologic map, which provides new information about the timing, compositions, and eruptive processes of Quaternary volcanism in Harrat Rahat. For example, prior mapping and geochronology undertaken during the 1980s suggested that the majority of mafic and silicic volcanics erupted during the Miocene and Pliocene, whereas several of the youngest-appearing lava flows were interpreted to be Neolithic ( 7,000 to 4,500 years BP) to post-Neolithic. New mapping and age-constrained stratigraphic relations indicate that all exposed volcanic units within the northern third of Harrat Rahat erupted during the Pleistocene, with the exception of a single Holocene eruption in 1256 AD. This new multidisciplinary mapping is critical for understanding

Recent volcanic activity on Venus - Evidence from radiothermal emissivity measurements

NASA Technical Reports Server (NTRS)

Robinson, Cordula A.; Wood, John A.

1993-01-01

Radiothermal emissivity measurements are analyzed in order to study large volcanic constructs on Venus and to correlate details of the reflectivity/emissivity patterns with geological landforms and stratigraphy visible in corresponding SAR images. There appears to be a correlation between locations on Venus where high emissivity at high altitudes and low emissivity at low altitudes are observed. These phenomena are attributed here to relatively recent volcanic activity: the former to summit eruptions that have not had time to weather to the low-emissivity state, the latter to continuing emission of volcanic gases from neighboring small plains volcanoes. The pattern of reflectivity and emissivity on Maat Mons is examined in the light of these findings. It is concluded that Maat Mons has undergone the most recent episode of volcanic activity of all the volcanoes studied here.

Age, geochemical and Sr Nd Pb isotopic constraints for mantle source characteristics and petrogenesis of Teru Volcanics, Northern Kohistan Terrane, Pakistan

NASA Astrophysics Data System (ADS)

Khan, S. D.; Stern, R. J.; Manton, M. I.; Copeland, P.; Kimura, J. I.; Khan, M. A.

2004-11-01

This paper presents new geochemical and geochronology data for the Teru Volcanic Formation (previously known as the Shamran Volcanics) exposed west of Gilgit in the Kohistan terrane of the Pakistani Himalayas. The Teru Volcanic Formation ranges from basalt through andesite to rhyolite and has subalkaline and midalkaline affinities. Trace-element compositions and isotopic characteristics suggest these magmas were formed in a subduction zone setting; isotopic studies also support this conclusion. It is suggested that these lavas originated from a depleted mantle source, which experienced contamination by variable subduction components. Model mixing calculations using 87Sr/ 86Sr and 143Nd/ 144Nd data suggest that addition of 0.2-0.6% of Indus margin sediments and/or 2-4% of fluids derived from Indus margin sediment can generate the compositional variation of the Teru Volcanic Formation. Two samples from the Teru Volcanic Formation yielded 40Ar/ 39Ar ages of 43.8+0.5 and 32.5+0.4 Ma. These ages make the volcanic rocks of the Teru Volcanic Formation the youngest reported in the Kohistan terrane. These volcanic rocks unconformably overly the Shunji Pluton, which has a 65 Ma Rb-Sr whole-rock isochron age. The results of this research suggest that subduction-related volcanism was active until 33 Ma in the India-Asia collision zone.

Volcanic ash in ancient Maya ceramics of the limestone lowlands: implications for prehistoric volcanic activity in the Guatemala highlands

NASA Astrophysics Data System (ADS)

Ford, Anabel; Rose, William I.

1995-07-01

In the spirit of collaborative research, Glicken and Ford embarked on the problem of identifying the source of volcanic ash used as temper in prehistoric Maya ceramics. Verification of the presence of glass shards and associated volcanic mineralogy in thin sections of Maya ceramics was straightforward and pointed to the Guatemala Highland volcanic chain. Considering seasonal wind rose patterns, target volcanoes include those from the area west of and including Guatemala City. Joint field research conducted in 1983 by Glicken and Ford in the limestone lowlands of Belize and neighboring Guatemala, 300 km north of the volcanic zone and 150 km from the nearest identified ash deposits, was unsuccessful in discovering local volcanic ash deposits. The abundance of the ash in common Maya ceramic vessels coupled with the difficulties of long-distance procurement without draft animals lead Glicken to suggest that ashfall into the lowlands would most parsimoniously explain prehistoric procurement; it literally dropped into their hands. A major archaeological problem with this explanation is that the use of volcanic ash occurring over several centuries of the Late Classic Period (ca. 600-900 AD). To accept the ashfall hypothesis for ancient Maya volcanic ash procurement, one would have to demonstrate a long span of consistent volcanic activity in the Guatemala Highlands for the last half of the first millennium AD. Should this be documented through careful petrographic, microprobe and tephrachronological studies, a number of related archaeological phenomena would be explained. In addition, the proposed model of volcanic activity has implications for understanding volcanism and potential volcanic hazards in Central America over a significantly longer time span than the historic period. These avenues are explored and a call for further collaborative research of this interdisciplinary problem is extended in this paper.

Volcanic Gases and Hot Spring Water to Evaluate the Volcanic Activity of the Mt. Baekdusan

NASA Astrophysics Data System (ADS)

Yun, S. H.; Lee, S.; Chang, C.

2017-12-01

This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu, also known as Changbaishan on the North Korea(DPRK)-China border, during the period from July 2015 to August 2016. Also, we confirmed the errors that HCO3- concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved CO2 in hot spring waters was analyzed using gas chromatograph in Lee et al.(2014). Improving this, from 2015, we used TOC-IC to analysis dissolved CO2. Also, we analyzed the Na2CO3 standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of the Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the HCO3-concentrations of 2014 samples. During the period of study, CO2/CH4 ratios in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction condition, and carbon in volcanic gases become more favorable to distribute into CH4 or CO than CO2. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of CO2which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cations, and some trace elements (As, Cd, Re).This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMIPA 2015-3060.

Catastrophic volcanism

NASA Technical Reports Server (NTRS)

Lipman, Peter W.

1988-01-01

Since primitive times, catastrophes due to volcanic activity have been vivid in the mind of man, who knew that his activities in many parts of the world were threatened by lava flows, mudflows, and ash falls. Within the present century, increasingly complex interactions between volcanism and the environment, on scales not previously experienced historically, have been detected or suspected from geologic observations. These include enormous hot pyroclastic flows associated with collapse at source calderas and fed by eruption columns that reached the stratosphere, relations between huge flood basalt eruptions at hotspots and the rifting of continents, devastating laterally-directed volcanic blasts and pyroclastic surges, great volcanic-generated tsunamis, climate modification from volcanic release of ash and sulfur aerosols into the upper atmosphere, modification of ocean circulation by volcanic constructs and attendent climatic implications, global pulsations in intensity of volcanic activity, and perhaps triggering of some intense terrestrial volcanism by planetary impacts. Complex feedback between volcanic activity and additional seemingly unrelated terrestrial processes likely remains unrecognized. Only recently has it become possible to begin to evaluate the degree to which such large-scale volcanic processes may have been important in triggering or modulating the tempo of faunal extinctions and other evolutionary events. In this overview, such processes are examined from the viewpoint of a field volcanologist, rather than as a previous participant in controversies concerning the interrelations between extinctions, impacts, and volcanism.

Oxygen isotope and trace element evidence for three-stage petrogenesis of the youngest episode (260-79 ka) of Yellowstone rhyolitic volcanism

NASA Astrophysics Data System (ADS)

Loewen, Matthew W.; Bindeman, Ilya N.

2015-10-01

We report the first high-precision δ18O analyses of glass, δ18O of minerals, and trace element concentrations in glass and minerals for the 260-79 ka Central Plateau Member (CPM) rhyolites of Yellowstone, a >350 km3 cumulative volume of lavas erupted inside of 630 ka Lava Creek Tuff (LCT) caldera. The glass analyses of these crystal-poor rhyolites provide direct characterization of the melt and its evolution through time. The δ18Oglass values are low and mostly homogeneous (4.5 ± 0.14 ‰) within and in between lavas that erupted in four different temporal episodes during 200 ka of CPM volcanism with a slight shift to lower δ18O in the youngest episode (Pitchstone Plateau). These values are lower than Yellowstone basalts (5.7-6 ‰), LCT (5.5 ‰), pre-, and extracaldera rhyolites (~7-8 ‰), but higher than the earliest 550-450 ka post-LCT rhyolites (1-2 ‰). The glass δ18O value is coupled with new clinopyroxene analyses and previously reported zircon analyses to calculate oxygen isotope equilibration temperatures. Clinopyroxene records >900 °C near-liquidus temperatures, while zircon records temperatures <850 °C similar to zircon saturation temperature estimates. Trace element concentrations in the same glass analyzed for oxygen isotopes show evidence for temporal decreases in Ti, Sr, Ba, and Eu—related to Fe-Ti oxide and sanidine (±quartz) crystallization control, while other trace elements remain similar or are enriched through time. The slight temporal increase in glass Zr concentrations may reflect similar or higher temperature magmas (via zircon saturation) through time, while previosuly reported temperature decreases (e.g., Ti-in-quartz) might reflect changing Ti concentrations with progressive melt evolution. Multiple analyses of glass across single samples and in profiles across lava flow surfaces document trace element heterogeneity with compatible behavior of all analyzed elements except Rb, Nb, and U. These new data provide evidence for a

Sensor web enables rapid response to volcanic activity

USGS Publications Warehouse

Davies, Ashley G.; Chien, Steve; Wright, Robert; Miklius, Asta; Kyle, Philip R.; Welsh, Matt; Johnson, Jeffrey B.; Tran, Daniel; Schaffer, Steven R.; Sherwood, Robert

2006-01-01

Rapid response to the onset of volcanic activity allows for the early assessment of hazard and risk [Tilling, 1989]. Data from remote volcanoes and volcanoes in countries with poor communication infrastructure can only be obtained via remote sensing [Harris et al., 2000]. By linking notifications of activity from ground-based and spacebased systems, these volcanoes can be monitored when they erupt.Over the last 18 months, NASA's Jet Propulsion Laboratory (JPL) has implemented a Volcano Sensor Web (VSW) in which data from ground-based and space-based sensors that detect current volcanic activity are used to automatically trigger the NASA Earth Observing 1 (EO-1) spacecraft to make highspatial-resolution observations of these volcanoes.

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

USGS Publications Warehouse

Pearson, S.C.P.; Connor, C.B.; Sanford, W.E.

2008-01-01

Hydrologic systems change in response to volcanic activity, and in turn may be sensitive indicators of volcanic activity. Here we investigate the coupled nature of magmatic and hydrologic systems using continuous multichannel time series of soil temperature collected on the flanks of Masaya volcano, Nicaragua, one of the most active volcanoes in Central America. The soil temperatures were measured in a low-temperature fumarole field located 3.5 km down the flanks of the volcano. Analysis of these time series reveals that they respond extremely rapidly, on a time scale of minutes, to changes in volcanic activity also manifested at the summit vent. These rapid temperature changes are caused by increased flow of water vapor through flank fumaroles during volcanism. The soil temperature response, ~5 °C, is repetitive and complex, with as many as 13 pulses during a single volcanic episode. Analysis of the frequency spectrum of these temperature time series shows that these anomalies are characterized by broad frequency content during volcanic activity. They are thus easily distinguished from seasonal trends, diurnal variations, or individual rainfall events, which triggered rapid transient increases in temperature during 5% of events. We suggest that the mechanism responsible for the distinctive temperature signals is rapid change in pore pressure in response to magmatism, a response that can be enhanced by meteoric water infiltration. Monitoring of distal fumaroles can therefore provide insight into coupled volcanic-hydrologic-meteorologic systems, and has potential as an inexpensive monitoring tool.

Modern volcanic activity on the Moon

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.

2018-05-01

Volcanic activity on the Moon began when its surface cooled, and the nucleus and mantle were clearly separated inside. Fragments of volcanic eruptions were discovered in the lunar soil, which was delivered to the Earth by "Apollo" spacecrafts. As shown by the analysis of some lunar meteorites, the first eruptions occurred 4.35 billion years ago. This is evidenced by the unique composition of the oxygen atoms for the Moon and on the radiocarbon analysis data. Well-visible on its surface, the dark "seas", which emerged shortly after the formation of the Moon, when the lowlands and large old craters were filled by liquid basaltic magma, rich in iron. The lunar "seas" are mostly on the visible side of the Moon, and cover almost a third of it; on the reverse side-the seas occupy less than 2%. Smooth surfaces of the seas mean that the lunar lava was very liquid. Therefore, at low gravity, it easily spread over a large area, almost without creating large cone-shaped peaks, but forming many small cone volcanic systems with an age of 3-4 billion years ago. On the images of the visible side of the Moon obtained with the help of the LRO, evidence is provided that volcanic eruptions on its surface were possible even a few million years ago.

Late-Pleistocene to precolumbian behind-the-arc mafic volcanism in the eastern Mexican Volcanic Belt; implications for future hazards

NASA Astrophysics Data System (ADS)

Siebert, Lee; Carrasco-Núñez, Gerardo

2002-06-01

An area of widespread alkaline-to-subalkaline volcanism lies at the northern end of the Cofre de Perote-Citlaltépetl (Pico de Orizaba) volcanic chain in the eastern Mexican Volcanic Belt (MVB). Two principal areas were active. About a dozen latest-Pleistocene to precolumbian vents form the 11-km-wide, E-W-trending Cofre de Perote vent cluster (CPVC) at 2300-2800 m elevation on the flank of the largely Pleistocene Cofre de Perote shield volcano and produced an extensive lava field that covers >100 km 2. More widely dispersed vents form the Naolinco volcanic field (NVF) in the Sierra de Chiconquiaco north of the city of Jalapa (Xalapa). Three generations of flows are delineated by cone and lava-flow morphology, degree of vegetation and cultivation, and radiocarbon dating. The flows lie in the behind-the-arc portion of the northeastern part of the MVB and show major- and trace-element chemical patterns transitional between intraplate and subduction zone environments. Flows of the oldest group originated from La Joya cinder cone (radiocarbon ages ˜42 000 yr BP) at the eastern end of the CPVC. This cone fed an olivine-basaltic flow field of ˜20 km 2 that extends about 14 km southeast to underlie the heavily populated northern outskirts of Jalapa, the capital city of the state of Veracruz. The Central Cone Group (CCG), of intermediate age, consists of four morphologically youthful cinder cones and associated vents that were the source of a lava field>27 km 2 of late-Pleistocene or Holocene age. The youngest group includes the westernmost flow, from Cerro Colorado, and a lava flow ˜2980 BP from the Rincón de Chapultepec scoria cone of the NVF. The latest eruption, from the compound El Volcancillo scoria cone, occurred about 870 radiocarbon years ago and produced two chemically and rheologically diverse lava flows that are among the youngest precolumbian flows in México and resemble paired aa-pahoehoe flows from Mauna Loa volcano. The El Volcancillo eruption

Dome collapse eruption in Tatun Volcanic Group near metropolitan Taipei, Taiwan at ~6 kyrs

NASA Astrophysics Data System (ADS)

Chen, C.; Lee, T.

2010-12-01

The Tatun Volcanic Group (TVG) is located in the north of metropolitan Taipei, Taiwan. Over 6 million inhabitants are living in Taipei City and suburban area. Another critical issue is an international airport and two nuclear power plants are lying at the foot of the TVG. If the TGV will be re-active, the serious hazard for human lives and economies in this area will definitely occur. Understanding the youngest eruption history of the TVG will be much important for prediction the future activity of eruption. The core was collected from the Dream Lake at the eastern slop of Cising Mt.. Total 21 samples from depth 190 cm to 231.5 cm have been tested. Comparison of chemical compositions of glass and minerals in the volcanic clasts with those of lava around TVG, they clearly showed that the volcanic clasts can be correlated with the eruption of the closest Cising Mt. According to the radiocarbon (C-14) age of core sample at the depth 225 cm, the age was extrapolated around 6150 yrs ca. C-14 B.P.. Moreover, the respiratory cristobalite in the volcanic clasts were firstly identified by the identical morphology, chemical composition and Laser Raman Spectrometry (LRS). The crystalline silica was produced by vapor-phase crystallization and devitrification in the andesite lava dome and volcanic ash generated by pyroclastic flows formed by lava dome collapse in Soufriere Hills volcano, Montserrat (Baxter et al.,1999). These new evidence demonstrated that there would probably have the lava dome collapse eruptions in the TVG in the last 6 kyrs. The result in this paper also sustained that the landslide caused by the weak phreatic eruption within the last 6000 yrs in the TVG (Belousov et al., 2010). It must further be noted that an efficient program of the volcanic hazard reduction should be practiced for the metropolitan Taipei and suburban area.

Frequency Based Volcanic Activity Detection through Remotely Sensed Data

NASA Astrophysics Data System (ADS)

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

2015-12-01

Satellite remote sensing has proved to offer a useful and relatively inexpensive method for monitoring large areas where field work is logistically unrealistic, and potentially dangerous. Current sensors are able to detect the majority of explosive volcanic activity; those that tend to effect and represent larger scale changes in the volcanic systems, eventually relating to ash producing periods of extended eruptive activity, and effusive activity. As new spaceborne sensors are developed, the ability to detect activity improves so that a system to gauge the frequency of volcanic activity can be used as a useful monitoring tool. Four volcanoes were chosen for development and testing of a method to monitor explosive activity: Stromboli (Italy); Shishaldin and Cleveland (Alaska, USA); and Karymsky (Kamchatka, Russia). Each volcano studied had similar but unique signatures of pre-cursory and eruptive activity. This study has shown that this monitoring tool could be applied to a wide range of volcanoes and still produce useful and robust data. Our method deals specifically with the detection of small scale explosive activity. The method described here could be useful in an operational setting, especially at remote volcanoes that have the potential to impact populations, infrastructure, and the aviation community. A number of important factors will affect the validity of application of this method. They are: (1) the availability of a continuous and continually populated dataset; (2) appropriate and reasonable sensor resolutions; (3) a recorded history of the volcano's previous activity; and, if available, (4) some ground-based monitoring system. We aim to develop the method further to be able to capture and evaluate the frequency of other volcanic processes such as lava flows, phreatomagmatic eruptions and dome growth and collapse. The work shown here has served to illustrate the capability of this method and monitoring tool for use at remote, un-instrumented volcanoes.

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

NASA Astrophysics Data System (ADS)

Londono, John Makario

2016-09-01

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

Classifying Volcanic Activity Using an Empirical Decision Making Algorithm

NASA Astrophysics Data System (ADS)

Junek, W. N.; Jones, W. L.; Woods, M. T.

2012-12-01

Detection and classification of developing volcanic activity is vital to eruption forecasting. Timely information regarding an impending eruption would aid civil authorities in determining the proper response to a developing crisis. In this presentation, volcanic activity is characterized using an event tree classifier and a suite of empirical statistical models derived through logistic regression. Forecasts are reported in terms of the United States Geological Survey (USGS) volcano alert level system. The algorithm employs multidisciplinary data (e.g., seismic, GPS, InSAR) acquired by various volcano monitoring systems and source modeling information to forecast the likelihood that an eruption, with a volcanic explosivity index (VEI) > 1, will occur within a quantitatively constrained area. Logistic models are constructed from a sparse and geographically diverse dataset assembled from a collection of historic volcanic unrest episodes. Bootstrapping techniques are applied to the training data to allow for the estimation of robust logistic model coefficients. Cross validation produced a series of receiver operating characteristic (ROC) curves with areas ranging between 0.78-0.81, which indicates the algorithm has good predictive capabilities. The ROC curves also allowed for the determination of a false positive rate and optimum detection for each stage of the algorithm. Forecasts for historic volcanic unrest episodes in North America and Iceland were computed and are consistent with the actual outcome of the events.

Geophysical Analysis of Young Monogenetic Volcanoes in the San Francisco Volcanic Field, Arizona

NASA Astrophysics Data System (ADS)

Rees, S.; Porter, R. C.; Riggs, N.

2017-12-01

The San Francisco Volcanic Field (SFVF), located in northern Arizona, USA, contains some of the youngest intracontinental volcanism within the United States and, given its recent eruptive history, presents an excellent opportunity to better understand how these systems behave. Geophysical techniques such as magnetics, paleomagnetics, and seismic refraction can be used to understand eruptive behavior and image shallow subsurface structures. As such, they present an opportunity to understand eruptive processes associated with the monogenetic volcanism that is common within the SFVF. These techniques are especially beneficial in areas where erosion has not exposed shallow eruptive features within the volcano. We focus on two volcanoes within the SFVF, Merriam Crater and Crater 120 for this work. These are thought to be some of the youngest volcanoes in the field and, as such, are well preserved. Aside from being young, they both exhibit interesting features such as multiple vents, apparent vent alignment, and lack of erosional features that are present at many of the other volcanoes in the SFVF, making them ideal for this work. Initial results show that shallow subsurface basaltic masses can be located using geophysical techniques. These masses are interpreted as dikes or lava flows that are covered by younger scoria. Propagating dikes drive eruptions at monogenetic volcanoes, which often appear in aligned clusters. Locating these features will further the understanding of how magma is transported and how eruptions may have progressed.

Clustering and Hazard Estimation in the Auckland Volcanic Field, New Zealand

NASA Astrophysics Data System (ADS)

Cronin, S. J.; Bebbington, M. S.

2009-12-01

clustering-based model of vent locations as originally applied by Magill et al (2005: Mathematical Geol. 37: 227-242) to the Allen and Smith (1994; Geosci. Report Shizuoka Univ 20: 5-14) age ordering of volcanism at AVF. Applying this model, modified by allowing continuation of activity at or around the youngest event, to sampled age orderings from the Monte Carlo procedure shows a very different spatial forecast to the earlier analysis. It is also different to the distribution from randomly ordered events, implying there is at least some clustering control on the location of eruptions in the field. Further iterations of this modelling approach will be tested in relation to eruptive volume and applied to other comparative volcanic fields.

Volcanic Hazards Survey in the Trans Mexican Volcanic Belt

NASA Technical Reports Server (NTRS)

Abrams, Michael; Siebe, Claus; Macias, Jose Luis

1996-01-01

We have assembled a digital mosaic of 11 Landsat Thematic images to serve as a mapping base for reconnaissance activities within the Trans Mexican Volcanic Belt. This will aid us in interpretation and in the evaluation of potential activity of all the volcanic centers there. One result is a volcanic hazards map of the area.

Volcanic hazard management in dispersed volcanism areas

NASA Astrophysics Data System (ADS)

Marrero, Jose Manuel; Garcia, Alicia; Ortiz, Ramon

2014-05-01

Traditional volcanic hazard methodologies were developed mainly to deal with the big stratovolcanoes. In such type of volcanoes, the hazard map is an important tool for decision-makers not only during a volcanic crisis but also for territorial planning. According to the past and recent eruptions of a volcano, all possible volcanic hazards are modelled and included in the hazard map. Combining the hazard map with the Event Tree the impact area can be zoned and defining the likely eruptive scenarios that will be used during a real volcanic crisis. But in areas of disperse volcanism is very complex to apply the same volcanic hazard methodologies. The event tree do not take into account unknown vents, because the spatial concepts included in it are only related with the distance reached by volcanic hazards. The volcanic hazard simulation is also difficult because the vent scatter modifies the results. The volcanic susceptibility try to solve this problem, calculating the most likely areas to have an eruption, but the differences between low and large values obtained are often very small. In these conditions the traditional hazard map effectiveness could be questioned, making necessary a change in the concept of hazard map. Instead to delimit the potential impact areas, the hazard map should show the expected behaviour of the volcanic activity and how the differences in the landscape and internal geo-structures could condition such behaviour. This approach has been carried out in La Palma (Canary Islands), combining the concept of long-term hazard map with the short-term volcanic scenario to show the expected volcanic activity behaviour. The objective is the decision-makers understand how a volcanic crisis could be and what kind of mitigation measurement and strategy could be used.

Volcanic Ash Activates the NLRP3 Inflammasome in Murine and Human Macrophages.

PubMed

Damby, David E; Horwell, Claire J; Baxter, Peter J; Kueppers, Ulrich; Schnurr, Max; Dingwell, Donald B; Duewell, Peter

2017-01-01

Volcanic ash is a heterogeneous mineral dust that is typically composed of a mixture of amorphous (glass) and crystalline (mineral) fragments. It commonly contains an abundance of the crystalline silica (SiO 2 ) polymorph cristobalite. Inhalation of crystalline silica can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that plays a critical role in driving inflammatory immune responses. Ingested material results in the assembly of NLRP3, ASC, and caspase-1 with subsequent secretion of the interleukin-1 family cytokine IL-1β. Previous toxicology work suggests that cristobalite-bearing volcanic ash is minimally reactive, calling into question the reactivity of volcanically derived crystalline silica, in general. In this study, we target the NLRP3 inflammasome as a crystalline silica responsive element to clarify volcanic cristobalite reactivity. We expose immortalized bone marrow-derived macrophages of genetically engineered mice and primary human peripheral blood mononuclear cells (PBMCs) to ash from the Soufrière Hills volcano as well as representative, pure-phase samples of its primary componentry (volcanic glass, feldspar, cristobalite) and measure NLRP3 inflammasome activation. We demonstrate that respirable Soufrière Hills volcanic ash induces the activation of caspase-1 with subsequent release of mature IL-1β in a NLRP3 inflammasome-dependent manner. Macrophages deficient in NLRP3 inflammasome components are incapable of secreting IL-1β in response to volcanic ash ingestion. Cellular uptake induces lysosomal destabilization involving cysteine proteases. Furthermore, the response involves activation of mitochondrial stress pathways leading to the generation of reactive oxygen species. Considering ash componentry, cristobalite is the most reactive pure-phase with other components inducing only low-level IL-1β secretion. Inflammasome activation mediated by inhaled ash and its potential relevance in chronic pulmonary

Volcanic ash activates the NLRP3 inflammasome in murine and human macrophages

USGS Publications Warehouse

Damby, David; Horwell, Claire J.; Baxter, Peter J.; Kueppers, Ulrich; Schnurr, Max; Dingwell, Donald B.; Duewell, Peter

2018-01-01

Volcanic ash is a heterogeneous mineral dust that is typically composed of a mixture of amorphous (glass) and crystalline (mineral) fragments. It commonly contains an abundance of the crystalline silica (SiO2) polymorph cristobalite. Inhalation of crystalline silica can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that plays a critical role in driving inflammatory immune responses. Ingested material results in the assembly of NLRP3, ASC, and caspase-1 with subsequent secretion of the interleukin-1 family cytokine IL-1β. Previous toxicology work suggests that cristobalite-bearing volcanic ash is minimally reactive, calling into question the reactivity of volcanically derived crystalline silica, in general. In this study, we target the NLRP3 inflammasome as a crystalline silica responsive element to clarify volcanic cristobalite reactivity. We expose immortalized bone marrow-derived macrophages of genetically engineered mice and primary human peripheral blood mononuclear cells (PBMCs) to ash from the Soufrière Hills volcano as well as representative, pure-phase samples of its primary componentry (volcanic glass, feldspar, cristobalite) and measure NLRP3 inflammasome activation. We demonstrate that respirable Soufrière Hills volcanic ash induces the activation of caspase-1 with subsequent release of mature IL-1β in a NLRP3 inflammasome-dependent manner. Macrophages deficient in NLRP3 inflammasome components are incapable of secreting IL-1β in response to volcanic ash ingestion. Cellular uptake induces lysosomal destabilization involving cysteine proteases. Furthermore, the response involves activation of mitochondrial stress pathways leading to the generation of reactive oxygen species. Considering ash componentry, cristobalite is the most reactive pure-phase with other components inducing only low-level IL-1β secretion. Inflammasome activation mediated by inhaled ash and its potential relevance in chronic pulmonary

Volcanic Ash Activates the NLRP3 Inflammasome in Murine and Human Macrophages

PubMed Central

Damby, David E.; Horwell, Claire J.; Baxter, Peter J.; Kueppers, Ulrich; Schnurr, Max; Dingwell, Donald B.; Duewell, Peter

2018-01-01

Volcanic ash is a heterogeneous mineral dust that is typically composed of a mixture of amorphous (glass) and crystalline (mineral) fragments. It commonly contains an abundance of the crystalline silica (SiO2) polymorph cristobalite. Inhalation of crystalline silica can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that plays a critical role in driving inflammatory immune responses. Ingested material results in the assembly of NLRP3, ASC, and caspase-1 with subsequent secretion of the interleukin-1 family cytokine IL-1β. Previous toxicology work suggests that cristobalite-bearing volcanic ash is minimally reactive, calling into question the reactivity of volcanically derived crystalline silica, in general. In this study, we target the NLRP3 inflammasome as a crystalline silica responsive element to clarify volcanic cristobalite reactivity. We expose immortalized bone marrow-derived macrophages of genetically engineered mice and primary human peripheral blood mononuclear cells (PBMCs) to ash from the Soufrière Hills volcano as well as representative, pure-phase samples of its primary componentry (volcanic glass, feldspar, cristobalite) and measure NLRP3 inflammasome activation. We demonstrate that respirable Soufrière Hills volcanic ash induces the activation of caspase-1 with subsequent release of mature IL-1β in a NLRP3 inflammasome-dependent manner. Macrophages deficient in NLRP3 inflammasome components are incapable of secreting IL-1β in response to volcanic ash ingestion. Cellular uptake induces lysosomal destabilization involving cysteine proteases. Furthermore, the response involves activation of mitochondrial stress pathways leading to the generation of reactive oxygen species. Considering ash componentry, cristobalite is the most reactive pure-phase with other components inducing only low-level IL-1β secretion. Inflammasome activation mediated by inhaled ash and its potential relevance in chronic pulmonary

Investigating the volcanic versus aqueous origin of the surficial deposits in Eastern Elysium Planitia, Mars

NASA Astrophysics Data System (ADS)

Voigt, Joana R. C.; Hamilton, Christopher W.

2018-07-01

The Elysium Volcanic Province consists of numerous overlapping flow units and may include the youngest lava flows on Mars. However, it is possible that these volcanic units have been modified or overprinted by aqueous processes. Understanding the timing of the igneous and aqueous events in this region is therefore essential for constraining the geological and environmental history of Mars during the Amazonian Period. We investigate the geologic evolution of Eastern Elysium Planitia to determine the relationship between major units, with the support of a geological map and chronological constraints from crater size-frequency distributions. We also evaluate the hypothesized origin of these units via volcanic, fluvial, and/or fluvioglacial processes using a detailed facies-mapping approach. The study area includes the Eastern Cerberus Fossae, Rahway Valles, and Marte Vallis. The surficial deposits in Rahway Valles were formerly interpreted to be modified by fluvial and fluvioglacial processes. However, our facies map reveals that the surface of Eastern Elysium Planitia includes nineteen morphologically distinct regions (i.e., facies), which are interpreted to be the products of flood lava volcanism, including: ´a´ā, pāhoehoe, and transitional lava flow types. In contrast to previous studies, which determined that Rahway Valles and Marte Vallis consist of two distinct geologic units with Middle to Late Amazonian ages, the results of this work show that the region was resurfaced by at least two volcanic flows with much younger ages of 20.0 Ma and 8.8 Ma. Furthermore, by coupling results of our geologic and facies mapping with chronological constraints as well as subsurface information provided by Shallow Radar reflectors, we show that there is an erosional unconformity located between the two youngest lava flow units in Marte Vallis. We interpret that this unconformity was generated by a catastrophic aqueous flooding event that occurred only 8.8 - 20.0 Ma ago. This

U.S. Geological Survey's Alert Notification System for Volcanic Activity

USGS Publications Warehouse

Gardner, Cynthia A.; Guffanti, Marianne C.

2006-01-01

The United States and its territories have about 170 volcanoes that have been active during the past 10,000 years, and most could erupt again in the future. In the past 500 years, 80 U.S. volcanoes have erupted one or more times. About 50 of these recently active volcanoes are monitored, although not all to the same degree. Through its five volcano observatories, the U.S. Geological Survey (USGS) issues information and warnings to the public about volcanic activity. For clarity of warnings during volcanic crises, the USGS has now standardized the alert-notification system used at its observatories.

Active Volcanic Plumes on Io

NASA Image and Video Library

1998-03-26

This color image, acquired during NASA Galileo ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon, erupting over a caldera volcanic depression named Pillan Patera.

Recurrence rate and magma effusion rate for the latest volcanism on Arsia Mons, Mars

NASA Astrophysics Data System (ADS)

Richardson, Jacob A.; Wilson, James A.; Connor, Charles B.; Bleacher, Jacob E.; Kiyosugi, Koji

2017-01-01

Magmatism and volcanism have evolved the Martian lithosphere, surface, and climate throughout the history of Mars. Constraining the rates of magma generation and timing of volcanism on the surface clarifies the ways in which magma and volcanic activity have shaped these Martian systems. The ages of lava flows on other planets are often estimated using impact crater counts, assuming that the number and size-distribution of impact craters per unit area reflect the time the lava flow has been on the surface and exposed to potential impacts. Here we show that impact crater age model uncertainty is reduced by adding stratigraphic information observed at locations where neighboring lavas abut each other, and demonstrate the significance of this reduction in age uncertainty for understanding the history of a volcanic field comprising 29 vents in the 110-km-diameter caldera of Arsia Mons, Mars. Each vent within this caldera produced lava flows several to tens of kilometers in length; these vents are likely among the youngest on Mars, since no impact craters in their lava flows are larger than 1 km in diameter. First, we modeled the age of each vent with impact crater counts performed on their corresponding lava flows and found very large age uncertainties for the ages of individual vents, often spanning the estimated age for the entire volcanic field. The age model derived from impact crater counts alone is broad and unimodal, with estimated peak activity in the field around 130 Ma. Next we applied our volcano event age model (VEAM), which uses a directed graph of stratigraphic relationships and random sampling of the impact crater age determinations to create alternative age models. Monte Carlo simulation was used to create 10,000 possible vent age sets. The recurrence rate of volcanism is calculated for each possible age set, and these rates are combined to calculate the median recurrence rate of all simulations. Applying this approach to the 29 volcanic vents, volcanism

Recurrence Rate and Magma Effusion Rate for the Latest Volcanism on Arsia Mons, Mars

NASA Technical Reports Server (NTRS)

Richardson, Jacob A.; Wilson, James A.; Connor, Charles B.; Bleacher, Jacob E.; Kiyosugi, Koji

2016-01-01

Magmatism and volcanism have evolved the Martian lithosphere, surface, and climate throughout the history of Mars. Constraining the rates of magma generation and timing of volcanism on the surface clarifies the ways in which magma and volcanic activity have shaped these Martian systems. The ages of lava flows on other planets are often estimated using impact crater counts, assuming that the number and size-distribution of impact craters per unit area reflect the time the lava flow has been on the surface and exposed to potential impacts. Here we show that impact crater age model uncertainty is reduced by adding stratigraphic information observed at locations where neighboring lavas abut each other, and demonstrate the significance of this reduction in age uncertainty for understanding the history of a volcanic field comprising 29 vents in the 110-kilometer-diameter caldera of Arsia Mons, Mars. Each vent within this caldera produced lava flows several to tens of kilometers in length; these vents are likely among the youngest on Mars, since no impact craters in their lava flows are larger than 1 kilometer in diameter. First, we modeled the age of each vent with impact crater counts performed on their corresponding lava flows and found very large age uncertainties for the ages of individual vents, often spanning the estimated age for the entire volcanic field. The age model derived from impact crater counts alone is broad and unimodal, with estimated peak activity in the field around 130Ma (megaannum, 1 million years). Next we applied our volcano event age model (VEAM), which uses a directed graph of stratigraphic relationships and random sampling of the impact crater age determinations to create alternative age models. Monte Carlo simulation was used to create 10,000 possible vent age sets. The recurrence rate of volcanism is calculated for each possible age set, and these rates are combined to calculate the median recurrence rate of all simulations. Applying this

Multidimensional analysis and probabilistic model of volcanic and seismic activities

NASA Astrophysics Data System (ADS)

Fedorov, V.

2009-04-01

A search for space and time regularities in volcanic and seismic events for the purpose of forecast method development seems to be of current concern, both scientifically and practically. The seismic and volcanic processes take place in the Earth's field of gravity which in turn is closely related to gravitational fields of the Moon, the Sun, and the planets of the Solar System. It is mostly gravity and tidal forces that exercise control over the Earth's configuration and relief. Dynamic gravitational interaction between the Earth and other celestial bodies makes itself evident in tidal phenomena and other effects in the geospheres (including the Earth's crust). Dynamics of the tidal and attractive forces is responsible for periodical changes in gravity force, both in value and direction [Darwin, 1965], in the rate of rotation and orbital speed; that implies related changes in the endogenic activity of the Earth. The Earth's rotation in the alternating gravitational field accounts to a considerable extent for regular pattern of crustal deformations and dislocations; it is among principal factors that control the Earth's form and structure, distribution of oceans and continents and, probably, continental drift [Peive, 1969; Khain, 1973; Kosygin, 1983]. The energy of gravitational interaction is transmitted through the tidal energy to planetary spheres and feeds various processes there, including volcanic and seismic ones. To determine degree, character and special features of tidal force contribution to the volcanic and seismic processes is of primary importance for understanding of genetic and dynamic aspects of volcanism and seismicity. Both volcanic and seismic processes are involved in evolution of celestial bodies; they are operative on the planets of the Earth group and many satellites [Essays…, 1981; Lukashov, 1996]. From this standpoint, studies of those processes are essential with a view to development of scenarios of the Earth's evolution as a celestial

The Lanzarote Geodynamic Laboratory: new capabilities for monitoring of volcanic activity at Canary Islands

NASA Astrophysics Data System (ADS)

Arnoso, J.; Vélez, E. J.; Soler, V.; Montesinos, F. G.; Benavent, M.

2012-04-01

The volcanic island of Lanzarote is located at the northeastern end of the Canary Islands. Together with Fuerteventura Island, Lanzarote constitutes the emergent part of the East Canary Ridge, which presents a NNE-SSW volcanic alignment. Last eruptive events took place in 1824 and during the period 1730-1736, which is the largest to occur in the archipelago and throw out about 1.3 km3 of volcanic materials. The Lanzarote Geodynamic Laboratory (LGL) was created in 1986 with the idea of making Lanzarote as a natural laboratory to carry out studies in order to acquire more knowledge about its origin, present status and evolution (Vieira et al., 1991; 2006). The LGL has a multidisciplinary scientific purpose and, among others, various objectives are devoted to investigate mass distribution in the Earth system and surface displacements associated to volcanic and/or seismic activity in the island. The influence of LGL is extended throughout the whole geographical area of Lanzarote, including small islands located at the north. The laboratory has 3 observing modules distributed along the island according to its infrastructure and scientific objectives, where more than 70 sensors are recording continuously gravity variations, ground deformations, sea level, seismic activity, meteorological parameters, etc. All these observations are supplemented by periodic measurement of geodetic and geophysical networks that allow us to make studies at local, insular and regional scales. The application of geodetic and geophysical techniques to identify geodynamic signals related to volcanic processes is then a permanent research activity of the laboratory. Nowadays, this fact becomes more interesting due to the ongoing volcanic eruption that is taking place in other island of the Canary Archipelago, El Hierro, since past July 2011. That is, the multidisciplinary research carry on up to now at the LGL allow us to apply multiparameter observations of different kinds of volcanic

Eighteen years of geochemical monitoring at the oceanic active volcanic island of El Hierro (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Asensio-Ramos, María; Alonso, Mar; Sharp, Emerson; Woods, Hannah; Barrancos, José; Pérez, Nemesio M.

2016-04-01

We report herein the latest results of a diffuse CO2 efflux survey at El Hierro volcanic system carried out during the summer period of 2015 to constrain the total CO2 output from the studied area a during post-eruptive period. El Hierro Island (278 km2) is the youngest and the SW-most of the Canary Islands. On July 16, 2011, a seismic-volcanic crisis started with the occurrence of more than 11,900 seismic events and significant deformation along the island. On October 10, 2011, the dominant character of seismicity changed dramatically from discrete earthquakes to continuous tremor, a clear indication that magma was rapidly approaching the surface immediately before the onset of the eruption, October 12. Eruption was declared over on 5 March, 2012. In order to monitor the volcanic activity of El Hierro Island, from 1998 to 2015 diffuse CO2 emission studies have been performed at El Hierro volcanic system in a yearly basis (˜600 observation sites) according to the accumulation chamber method. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. To quantify the total CO2 emission from the studied area, 100 simulations for each survey have been performed. During the eruption period, soil CO2 efflux values range from non-detectable (˜0.5 g m-2 d-1) up to 457 g m-2 d-1, reaching in November 27, 2011, the maximum CO2 output estimated value of all time series, 2,398 t d-1, just before the episodes of maximum degassing observed as vigorous bubbling at the sea surface and an increment in the amplitude of the tremor signal. During the 2015 survey, soil CO2 efflux values ranged from non-detectable up to 41 g m-2 d-1. The spatial distribution of diffuse CO2 emission values seemed to be controlled by the main volcano structural features of the island. The total diffuse CO2 output released to atmosphere was estimated at 575 ± 24 t d-1, value slightly higher that the background CO2 emission estimated at 422 t d-1 (Melián et

Recent and Hazardous Volcanic Activity Along the NW Rift Zone of Piton De La Fournaise Volcano, La Réunion Island

NASA Astrophysics Data System (ADS)

Walther, G.; Frese, I.; Di Muro, A.; Kueppers, U.; Michon, L.; Metrich, N.

2014-12-01

Shield volcanoes are a common feature of basaltic volcanism. Their volcanic activity is often confined to a summit crater area and rift systems, both characterized by constructive (scoria and cinder cones; lava flows) and destructive (pit craters; caldera collapse) phenomena. Piton de la Fournaise (PdF) shield volcano (La Réunion Island, Indian Ocean) is an ideal place to study these differences in eruptive behaviour. Besides the frequent eruptions in the central Enclos Fouqué caldera, hundreds of eruptive vents opened along three main rift zones cutting the edifice during the last 50 kyrs. Two short rift zones are characterized by weak seismicity and lateral magma transport at shallow depth (above sea level). Here we focus on the third and largest rift zone (15km wide, 20 km long), which extends in a north-westerly direction between PdF and nearby Piton des Neiges volcanic complex. It is typified by deep seismicity (up to 30 km), emitting mostly primitive magmas, testifying of high fluid pressures (up to 5 kbar) and large-volume eruptions. We present new field data (including stratigraphic logs, a geological map of the area, C-14 dating and geochemical analyses of the eruption products) on one of the youngest (~6kyrs) and largest lava field (Trous Blancs eruption). It extends for 24km from a height of 1800 m asl, passing Le Tampon and Saint Pierre cities, until reaching the coast. The source area of this huge lava flow has been identified in an alignment of four previously unidentified pit craters. The eruption initiated with intense fountaining activity, producing a m-thick bed of loose black scoria, which becomes densely welded in its upper part; followed by an alternation of volume rich lava effusions and strombolian activity, resulting in the emplacement of meter-thick, massive units of olivine-basalt alternating with coarse scoria beds in the proximal area. Activity ended with the emplacement of a dm-thick bed of glassy, dense scoria and a stratified lithic

Explosive Volcanic Activity at Extreme Depths: Evidence from the Charles Darwin Volcanic Field, Cape Verdes

NASA Astrophysics Data System (ADS)

Kwasnitschka, T.; Devey, C. W.; Hansteen, T. H.; Freundt, A.; Kutterolf, S.

2013-12-01

Volcanic eruptions on the deep sea floor have traditionally been assumed to be non-explosive as the high-pressure environment should greatly inhibit steam-driven explosions. Nevertheless, occasional evidence both from (generally slow-) spreading axes and intraplate seamounts has hinted at explosive activity at large water depths. Here we present evidence from a submarine field of volcanic cones and pit craters called Charles Darwin Volcanic Field located at about 3600 m depth on the lower southwestern slope of the Cape Verdean Island of Santo Antão. We examined two of these submarine volcanic edifices (Tambor and Kolá), each featuring a pit crater of 1 km diameter, using photogrammetric reconstructions derived from ROV-based imaging followed by 3D quantification using a novel remote sensing workflow, aided by sampling. The measured and calculated parameters of physical volcanology derived from the 3D model allow us, for the first time, to make quantitative statements about volcanic processes on the deep seafloor similar to those generated from land-based field observations. Tambor cone, which is 2500 m wide and 250 m high, consists of dense, probably monogenetic medium to coarse-grained volcaniclastic and pyroclastic rocks that are highly fragmented, probably as a result of thermal and viscous granulation upon contact with seawater during several consecutive cycles of activity. Tangential joints in the outcrops indicate subsidence of the crater floor after primary emplacement. Kolá crater, which is 1000 m wide and 160 m deep, appears to have been excavated in the surrounding seafloor and shows stepwise sagging features interpreted as ring fractures on the inner flanks. Lithologically, it is made up of a complicated succession of highly fragmented deposits, including spheroidal juvenile lapilli, likely formed by spray granulation. It resembles a maar-type deposit found on land. The eruption apparently entrained blocks of MORB-type gabbroic country rocks with

Volcanic Constructs on Ganymede and Enceladus: Topographic Evidence from Stereo Images and Photoclinometry

NASA Technical Reports Server (NTRS)

Schenk, Paul M.; Moore, Jeffrey M.

1995-01-01

The morphology of volcanic features on Ganymede differs significantly from that on the terrestrial planets. Few if any major volcanic landforms, such as thick flows or shield volcanoes, have been identified to date. Using new stereo Voyager images, we have searched Ganymede for relief-generating volcanic constructs. We observed seven major types of volcanic structures, including several not previously recognized. The oldest are broad flat-topped domes partially filling many older craters in dark terrain. Similar domes occur on Enceladus. Together with smooth dark deposits, these domes indicate that the volcanic history of the dark terrain is complex. Bright terrain covers vast areas, although the style of emplacement remains unclear. Smooth bright materials embay and flood older terrains, and may have been emplaced as low- viscosity fluids. Associated with smooth bright material are a number of scalloped-shaped, semi- enclosed scarps that cut into preexisting terrain. In planform these structures resemble terrestrial calderas. The youngest volcanic materials identified are a series of small flows that may have flooded the floor of the multiring impact structure Gilgamesh, forming a broad dome, The identification of volcanic constructs up to I km thick is the first evidence for extrusion of moderate-to-high viscosity material on Ganymede. Viscosity and yield strength estimates for these materials span several orders of magnitude, indicating that volcanic materials on Ganymede have a range of compositions and/or were extruded under a wide range of conditions and/or eruptive styles.

Experimental study on the effect of calcination on the volcanic ash activity of diatomite

NASA Astrophysics Data System (ADS)

Xiao, Liguang; Pang, Bo

2017-09-01

The volcanic ash activity of diatomite was studied under the conditions of aerobic calcination and vacuum calcination by the combined water rate method, it was characterized by XRD, BET and SEM. The results showed that the volcanic ash activity of diatomite under vacuum conditions was higher than that of aerobic calcination, 600°C vacuum calcination 2h, the combined water rate of diatomite-Ca(OH)2-H2O system was increased from 6.24% to 71.43%, the volcanic ash activity reached the maximum value, the specific surface

Volcanic Activity at Tvashtar Catena, Io

NASA Technical Reports Server (NTRS)

Milazzo, M. P.; Keszthelyi, L. P.; Radebaugh, J.; Davies, A. G.; McEwen, A. S.

2004-01-01

Tvashtar Catena (63 N, 120 W) is one of the most interesting features on Io. This chain of large paterae (caldera-like depressions) has exhibited highly variable volcanic activity in a series of observations. Tvashtar is the type example of a style of volcanism seen only at high latitudes, with short-lived Pele-type plumes and short-lived by intense thermal events. Evidence for a hot spot at Tvashtar was first detected in an eclipse observation in April 1997 (orbit G7) by the Solid State Imager (SSI) on the Galileo Spacecraft. Tvashtar was originally targeted for observation at higher resolution in the close flyby in November 1999 (I25) because of its interesting large-scale topography. There are relatively few but generally larger paterae at high latitudes on Io. I25 images revealed a 25 km long, 1-2 km high lava curtain via a pattern of saturation and bleeding in the CCD image, which requires very high temperatures.

Volcanic eruptions and solar activity

NASA Technical Reports Server (NTRS)

Stothers, Richard B.

1989-01-01

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

Characterizing volcanic activity: Application of freely-available webcams

NASA Astrophysics Data System (ADS)

Dehn, J.; Harrild, M.; Webley, P. W.

2017-12-01

In recent years, freely-available web-based cameras, or webcams, have become more readily available allowing an increased level of monitoring at active volcanoes across the globe. While these cameras have been extensively used as qualitative tools, they provide a unique dataset to perform quantitative analyzes of the changing behavior of the particular volcano within the cameras field of view. We focus on the multitude of these freely-available webcams and present a new algorithm to detect changes in volcanic activity using nighttime webcam data. Our approach uses a quick, efficient, and fully automated algorithm to identify changes in webcam data in near real-time, including techniques such as edge detection, Gaussian mixture models, and temporal/spatial statistical tests, which are applied to each target image. Often the image metadata (exposure, gain settings, aperture, focal length, etc.) are unknown, meaning we developed our algorithm to identify the quantity of volcanically incandescent pixels as well as the number of specific algorithm tests needed to detect thermal activity, instead of directly correlating brightness in the webcam to eruption temperatures. We compared our algorithm results to a manual analysis of webcam data for several volcanoes and determined a false detection rate of less than 3% for the automated approach. In our presentation, we describe the different tests integrated into our algorithm, lessons learned, and how we applied our method to several volcanoes across the North Pacific during its development and implementation. We will finish with a discussion on the global applicability of our approach and how to build a 24/7, 365 day a year tool that can be used as an additional data source for real-time analysis of volcanic activity.

Sandstone provenance and U-Pb ages of detrital zircons from Permian-Triassic forearc sediments within the Sukhothai Arc, northern Thailand: Record of volcanic-arc evolution in response to Paleo-Tethys subduction

NASA Astrophysics Data System (ADS)

Hara, Hidetoshi; Kunii, Miyuki; Miyake, Yoshihiro; Hisada, Ken-ichiro; Kamata, Yoshihito; Ueno, Katsumi; Kon, Yoshiaki; Kurihara, Toshiyuki; Ueda, Hayato; Assavapatchara, San; Treerotchananon, Anuwat; Charoentitirat, Thasinee; Charusiri, Punya

2017-09-01

Provenance analysis and U-Pb dating of detrital zircons in Permian-Triassic forearc sediments from the Sukhothai Arc in northern Thailand clarify the evolution of a missing arc system associated with Paleo-Tethys subduction. The turbidite-dominant formations within the forearc sediments include the Permian Ngao Group (Kiu Lom, Pha Huat, and Huai Thak formations), the Early to earliest Late Triassic Lampang Group (Phra That and Hong Hoi formations), and the Late Triassic Song Group (Pha Daeng and Wang Chin formations). The sandstones are quartzose in the Pha Huat, Huai Thak, and Wang Chin formations, and lithic wacke in the Kiu Lom, Phra That, Hong Hoi and Pha Daeng formations. The quartzose sandstones contain abundant quartz, felsic volcanic and plutonic fragments, whereas the lithic sandstones contain mainly basaltic to felsic volcanic fragments. The youngest single-grain (YSG) zircon U-Pb age generally approximates the depositional age in the study area, but in the case of the limestone-dominant Pha Huat Formation the YSG age is clearly older. On the other hand, the youngest cluster U-Pb age (YC1σ) represents the peak of igneous activity in the source area. Geological evidence, geochemical signatures, and the YC1σ ages of the sandstones have allowed us to reconstruct the Sukhothai arc evolution. The initial Sukhothai Arc (Late Carboniferous-Early Permian) developed as a continental island arc. Subsequently, there was general magmatic quiescence with minor I-type granitic activity during the Middle to early Late Permian. In the latest Permian to early Late Triassic, the Sukhothai Arc developed in tandem with Early to Middle Triassic I-type granitic activity, Middle to Late Triassic volcanism, evolution of an accretionary complex, and an abundant supply of sediments from the volcanic rocks to the trench through a forearc basin. Subsequently, the Sukhothai Arc became quiescent as the Paleo-Tethys closed after the Late Triassic. In addition, parts of sediments of

The Snake River Plain Volcanic Province: Insights from Project Hotspot

NASA Astrophysics Data System (ADS)

Shervais, J. W.; Potter, K. E.; Hanan, B. B.; Jean, M. M.; Duncan, R. A.; Champion, D. E.; Vetter, S.; Glen, J. M. G.; Christiansen, E. H.; Miggins, D. P.; Nielson, D. L.

2017-12-01

The Snake River Plain (SRP) Volcanic Province is the best modern example of a time-transgressive hotspot track beneath continental crust. The SRP began 17 Ma with massive eruptions of Columbia River basalt and rhyolite. After 12 Ma volcanism progressed towards Yellowstone, with early rhyolite overlain by basalts that may exceed 2 km thick. The early rhyolites are anorogenic with dry phenocryst assemblages and eruption temperatures up to 950C. Tholeiitic basalts have major and trace element compositions similar to ocean island basalts (OIB). Project Hotspot cored three deep holes in the central and western Snake River Plain: Kimama (mostly basalt), Kimberly (mostly rhyolite), and Mountain Home (lake sediments and basaslt). The Kimberly core documents rhyolite ash flows up to 700 m thick, possibly filling a caldera or sag. Chemical stratigraphy in Kimama and other basalt cores document fractional crystallization in relatively shallow magma chambers with episodic magma recharge. Age-depth relations in the Kimama core suggest accumulation rates of roughly 305 m/Ma. Surface and subsurface basalt flows show systematic variations in Sr-Nd-Pb isotopes with distance from Yellowstone interpreted to reflect changes in the proportion of plume source and the underlying heterogeneous cratonic lithosphere, which varies in age, composition, and thickness from west to east. Sr-Nd-Pb isotopes suggest <5% lithospheric input into a system dominated by OIB-like plume-derived basalts. A major flare-up of basaltic volcanism occurred 75-780 ka throughout the entire SRP, from Yellowstone in the east to Boise in the west. The youngest western SRP basalts are transitional alkali basalts that range in age from circa 900 ka to 2 ka, with trace element and isotopic compositions similar to the plume component of Hawaiian basalts. These observations suggest that ancient SCLM was replaced by plume mantle after the North America passed over the hotspot in the western SRP, which triggered renewed

Episodes of fluvial and volcanic activity in Mangala Valles, Mars

PubMed Central

Keske, Amber L.; Hamilton, Christopher W.; McEwen, Alfred S.; Daubar, Ingrid J.

2017-01-01

A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ~1 Ga, (2) emplacement of Tharsis lava flows in the valley from ~700 to 1000 Ma, (3) a megaflooding event at ~700–800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ~400–500 Ma, (5) another megaflooding event from ~400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ~300–350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ~300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars. PMID:29176911

Episodes of fluvial and volcanic activity in Mangala Valles, Mars.

PubMed

Keske, Amber L; Hamilton, Christopher W; McEwen, Alfred S; Daubar, Ingrid J

2015-01-01

A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ~1 Ga, (2) emplacement of Tharsis lava flows in the valley from ~700 to 1000 Ma, (3) a megaflooding event at ~700-800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ~400-500 Ma, (5) another megaflooding event from ~400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ~300-350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ~300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars.

Soil radon measurements as a potential tracer of tectonic and volcanic activity.

PubMed

Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

2016-04-15

In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009-2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

Soil radon measurements as a potential tracer of tectonic and volcanic activity

NASA Astrophysics Data System (ADS)

Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

2016-04-01

In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009-2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

Soil radon measurements as a potential tracer of tectonic and volcanic activity

PubMed Central

Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

2016-01-01

In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes. PMID:27079264

Implications of new stratigraphic data on volcanic hazard assessment for Nisyros volcano, Greece

NASA Astrophysics Data System (ADS)

Volentik, A.; Vanderkluysen, L.; Principe, C.; Hernandez, J.; Hunziker, J. C.

2003-04-01

The active quaternary Nisyros volcano, at the eastern end of the Aegean volcanic arc, is composed of a succession of lava flows, tephra layers and interbedded epiclastic deposits. The volcano is topped by a recent caldera, on average 4 km in diameter and 200 m in depth. A detailed geological map including 35 stratigraphic units (lava flows, tephra layers and epiclastic deposits) has been recently completed at the 1:10'000 scale, based on new stratigraphical data. Based on the identification of new plinian sequences (Lakki and Melisseri pyroclastic series) in the lowermost section of the reconstructed stratigraphical succession, on the re-interpretation of previously described deposits and on the discovery of eruptive facies, we construct a set of hazard maps for volcanic events at Nisyros. Sequences of sub-marine lavas to subaerial epiclastites combined with the occurrence of a marine terrace deposit in the north-western sector of the island highlight the potential for rapid vertical movements, in particular in the area of Mandraki. A period of intense off-centred strombolian to phreatomagmatic activity occurred in quite recent times on Nisyros along the major tectonic trends (N^o030, No070, N^o120 and N^o340), building up several scoria cones and tuff cones all around the island. A number of these tectonic trends are still active, as demonstrated by faults cutting through recent deposits (including the youngest deposits of the hydrothermal eruptions, inside the present caldera of Nisyros). This implies that not only intra-caldera phreatic eruptions, but also potential magmatic eruption may occur along the island’s major zones of weakness, with increased hazards where magma/water interaction may take place. Finally a newly recognized debris avalanche deposit (the so-called Vunàri debris avalanche), affecting a wide sector in the northern part of the island, unveils a new type of volcanic hazard on Nisyros, related to flank collapse and destruction of the

Monogenetic Volcano Clusters within the wider Michoacán-Guanajuato Volcanic Field (México) and their Significance

NASA Astrophysics Data System (ADS)

Siebe, C.

2017-12-01

The Trans-Mexican Volcanic Belt, one of the most complex and active continental arcs worldwide, displays several volcanic fields dominated by monogenetic volcanoes. Of these, the Plio-Quaternary Michoacán-Guanajuato Volcanic Field (MGVF) situated in central Mexico, is the largest monogenetic volcanic field in the world and includes more than 1000 scoria cones and associated lava flows and about 400 medium-sized volcanoes (Mexican shields). The smaller monogenetic vents occur either isolated or form small clusters within the wider MGVF. The recent identification of small clusters comprising several monogenetic volcanoes that erupted in a sequence of geologically short time intervals (hundreds to few thousands of years) in small areas within the much wider MGVF opens several questions in regard to future volcanic hazard assessments in this region: Are the youngest (Holocene) clusters still "active" and is a new eruption likely to occur within their surroundings? How long are such clusters "active"? Will the next monogenetic eruption in the MGVF be a single short-lived isolated eruption, or the beginning of a cluster? Furthermore, is it possible that the historic eruptions of Jorullo (1759) and Paricutin (1943) represent each the beginning of a cluster and should a new eruption in their proximity be expected in the future? In order to address these questions, two Holocene clusters, namely Tacámbaro and Malpaís de Zacapu are currently under study and preliminary results will be presented. Each comprises four monogenetic vents that erupted in a sequence of geologically short time intervals (hundreds to few thousands of years) within a small area (few tens of km2) Geologic mapping, geochemical analyses, radiometric dating, and paleomagnetic studies will help to establish the sequence of eruption of the different vents, and shed more light on the conditions that allow several magma sources to be formed and then tapped in close temporal and spatial proximity to each

Rapid extension in an Eocene volcanic arc: Structure and paleogeography of an intra-arc half graben in central Idaho

USGS Publications Warehouse

Janecke, S.U.; Hammond, B.F.; Snee, L.W.; Geissman, J.W.

1997-01-01

A study of extension, volcanism, and sedimentation in the middle Eocene Panther Creek half graben in central Idaho shows that it formed rapidly during an episode of voluminous volcanism. The east-southeast-tilted Panther Creek half graben developed across the northeast edge of the largest cauldron complex of the Challis volcanic field and along the northeast-trending Trans-Challis fault zone. Two normal fault systems bound the east side of the half graben. One fault system strikes northeast, parallel to the Trans-Challis fault zone, and the other strikes north to northwest. The geometry of the basin-fill deposits shows that movement on these two normal fault systems was synchronous and that both faults controlled the development of the Panther Creek half graben. Strikes of the synextension volcanic and sedimentary rocks are similar throughout the half graben, whereas dips decrease incrementally upsection from as much as 60?? to less than 10??. Previous K-Ar dates and a new 40Ar/39Ar plateau date from the youngest widespread tuff in the basin suggest that most of basin formation spanned 3 m.y. between about 47.7 Ma and 44.5 Ma. As much as 6.5 km of volcanic and sedimentary rocks were deposited during that time. Although rates of extension and subsidence were very high, intense volcanic activity continually filled the basin with ash-flow tuffs, outpacing subsidence and sedimentation, until the end of basin development. After the abrupt end of Challis volcanism, locally derived pebble to boulder conglomerate and massive, reworked ash accumulated in the half graben. These sedimentary rocks make up a small part of the basin fill in the Panther Creek half graben and were derived mainly from Proterozoic metasedimentary rocks uplifted in the footwall of the basin. The east-southeast tilt of the sedimentary rocks, their provenance and coarse grain size, and the presence of a gravity slide block derived from tilted volcanic rocks in the hanging wall attest to continued

SO2 on Venus: IUE, HST and ground-based measurements, and the active volcanism connection

NASA Technical Reports Server (NTRS)

Na, C. Y.; Barker, E. S.; Stern, S. A.; Esposito, L. W.

1993-01-01

Magellan images have shown that the volcanic features are widespread over the surface of Venus. The question of whether there is active volcanism is important for understanding both the atmospheric and the geological processes on Venus. The thick cloud cover of Venus precludes any direct observation of active volcanoes even if they exist. The only means of monitoring the active volcanism on Venus at present seems to be remote sensing from Earth. Continuous monitoring of SO2 is important to establish the long term trend of SO2 abundance and to understand the physical mechanism responsible for the change.

Impact of Volcanic Activity on AMC Channel Operations

DTIC Science & Technology

2014-06-13

active volcanic settings in the world. The location and behavior of volcanoes are a direct result of tectonic plate boundaries and the dynamic nature...Figure 2: Ash Detected Outside Iceland within 40°–70°N and 40°W–30°E (Scientific Reports, 2014) The potential for tectonic plate movement

Multi-Source Autonomous Response for Targeting and Monitoring of Volcanic Activity

NASA Technical Reports Server (NTRS)

Davies, Ashley G.; Doubleday, Joshua R.; Tran, Daniel Q.

2014-01-01

The study of volcanoes is important for both purely scientific and human survival reasons. From a scientific standpoint, volcanic gas and ash emissions contribute significantly to the terrestrial atmosphere. Ash depositions and lava flows can also greatly affect local environments. From a human survival standpoint, many people live within the reach of active volcanoes, and therefore can be endangered by both atmospheric (ash, debris) toxicity and lava flow. There are many potential information sources that can be used to determine how to best monitor volcanic activity worldwide. These are of varying temporal frequency, spatial regard, method of access, and reliability. The problem is how to incorporate all of these inputs in a general framework to assign/task/reconfigure assets to monitor events in a timely fashion. In situ sensing can provide a valuable range of complementary information such as seismographic, discharge, acoustic, and other data. However, many volcanoes are not instrumented with in situ sensors, and those that have sensor networks are restricted to a relatively small numbers of point sensors. Consequently, ideal volcanic study synergistically combines space and in situ measurements. This work demonstrates an effort to integrate spaceborne sensing from MODIS (Terra and Aqua), ALI (EO-1), Worldview-2, and in situ sensing in an automated scheme to improve global volcano monitoring. Specifically, it is a "sensor web" concept in which a number of volcano monitoring systems are linked together to monitor volcanic activity more accurately, and this activity measurement automatically tasks space assets to acquire further satellite imagery of ongoing volcanic activity. A general framework was developed for evidence combination that accounts for multiple information sources in a scientist-directed fashion to weigh inputs and allocate observations based on the confidence of an events occurrence, rarity of the event at that location, and other scientists

2014 volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory

USGS Publications Warehouse

Cameron, Cheryl E.; Dixon, James P.; Neal, Christina A.; Waythomas, Christopher F.; Schaefer, Janet R.; McGimsey, Robert G.

2017-09-07

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2014. The most notable volcanic activity consisted of intermittent ash eruptions from long-active Cleveland and Shishaldin Volcanoes in the Aleutian Islands, and two eruptive episodes at Pavlof Volcano on the Alaska Peninsula. Semisopochnoi and Akutan volcanoes had seismic swarms, both likely the result of magmatic intrusion. The AVO also installed seismometers and infrasound instruments at Mount Cleveland during 2014.

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Volcanism on Mercury

NASA Astrophysics Data System (ADS)

Rothery, David A.

2017-12-01

Mercury has no recognized tracts of intact primary crust analogous to lunar highland crust, probably because Mercury's iron-poor magma ocean was insufficiently dense to enable crystallized silicates to float. Its surface is accepted to consist mostly of multiple generations of lavas, rather like terrestrial "large igneous provinces" or LIPs, emplaced in greatest volumes prior to about 3.5 Ga. Subsequently, erupted volumes decreased, and became largely confined to impact craters. Plains younger than about 3.7 Ga are scarred by so few impact craters that they are mapped as "smooth plains." Older plains are termed "intercrater plains." There is no consensus on whether plains with characteristics intermediate between smooth and intercrater plains can be consistently mapped (as "intermediate plains"). The volcanic nature of Mercury's smooth plains was ambiguous on images returned by the first mission to Mercury, Mariner 10 (three flybys in 1974–1975. Better imaging by MESSENGER (in orbit 2011–2015) removed doubt by documenting innumerable ghost craters and wrinkle ridges. Vents are obscure, as is normal in LIPs, but there are good examples of streamlined islands showing the passage of fast-flowing, low-viscosity lava. The causes of mantle partial melting necessary to supply Mercury's eruptions are unclear, but secular cooling of a small, one-plate planet is expected to lead to the decrease in volcanic activity that we observe. Factors include loss of primordial heat and declining rate of radiogenic heat production, and closure of pathways by planetary thermal contraction. Lava compositions resemble komatiites but with low iron content. Regional variations may reflect lateral and vertical heterogeneities in the mantle, or different degrees of partial melting. The cessation of effusive volcanism on Mercury is hard to date because the youngest areas are small. However, it probably continued until about 1 Ga. That was not the end of volcanism on the planet. MESSENGER

Volcanic hazards to airports

USGS Publications Warehouse

Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.

2009-01-01

Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by volcanic activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by volcanic activity, which indicates that volcanic hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by volcanic hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby volcanic activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by volcanic activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies

Volcanism Studies: Final Report for the Yucca Mountain Project

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

Bruce M. Crowe; Frank V. Perry; Greg A. Valentine

1998-12-01

This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period ofmore » a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone

Volcanic Alert System (VAS) developed during the (2011-2013) El Hierro (Canary Islands) volcanic process

NASA Astrophysics Data System (ADS)

Ortiz, Ramon; Berrocoso, Manuel; Marrero, Jose Manuel; Fernandez-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Garcia, Alicia

2014-05-01

In volcanic areas with long repose periods (as El Hierro), recently installed monitoring networks offer no instrumental record of past eruptions nor experience in handling a volcanic crisis. Both conditions, uncertainty and inexperience, contribute to make the communication of hazard more difficult. In fact, in the initial phases of the unrest at El Hierro, the perception of volcanic risk was somewhat distorted, as even relatively low volcanic hazards caused a high political impact. The need of a Volcanic Alert System became then evident. In general, the Volcanic Alert System is comprised of the monitoring network, the software tools for the analysis of the observables, the management of the Volcanic Activity Level, and the assessment of the threat. The Volcanic Alert System presented here places special emphasis on phenomena associated to moderate eruptions, as well as on volcano-tectonic earthquakes and landslides, which in some cases, as in El Hierro, may be more destructive than an eruption itself. As part of the Volcanic Alert System, we introduce here the Volcanic Activity Level which continuously applies a routine analysis of monitoring data (particularly seismic and deformation data) to detect data trend changes or monitoring network failures. The data trend changes are quantified according to the Failure Forecast Method (FFM). When data changes and/or malfunctions are detected, by an automated watchdog, warnings are automatically issued to the Monitoring Scientific Team. Changes in the data patterns are then translated by the Monitoring Scientific Team into a simple Volcanic Activity Level, that is easy to use and understand by the scientists and technicians in charge for the technical management of the unrest. The main feature of the Volcanic Activity Level is its objectivity, as it does not depend on expert opinions, which are left to the Scientific Committee, and its capabilities for early detection of precursors. As a consequence of the El Hierro

Xanthogranulomatous Salpingooophoritis: The Youngest Documented Case Report

PubMed Central

Tanwar, Harshawardhan; Joshi, Avinash; Wagaskar, Vinayak; Kini, Siddharth; Bachhav, Manoj

2015-01-01

Background. Xanthogranulomatous inflammation is an uncommon affection of the female genital tract. The youngest case reported of xanthogranulomatous salpingooophoritis in literature was by Shilpa et al. in 2013 in an eighteen-year-old female. Case Report. We report a case of 2-year-old female child with right-sided xanthogranulomatous salpingooophoritis presented as mass in abdomen. This is a case report of the youngest documented case of xanthogranulomatous salpingooophoritis in literature. As per abdominal examination, there was generalized distention of abdomen and a mass was palpable which was arising out of pelvis more on the right side. The ultrasonography (USG) abdomen and pelvis revealed a thick-walled mass measuring 9.2 cm × 6.0 cm × 7.6 cm in pelvis. We did right salpingooophorectomy of the patient. On histopathology, the diagnosis of xanthogranulomatous salpingooophoritis was confirmed. Conclusion. Clinical presentation, radiological appearance, and gross features of xanthogranulomatous lesions of ovary can mimic neoplastic lesions and lead to misdiagnosis. Though, it is very rare in pediatric age group, xanthogranulomatous salpingooophoritis as one of the differential diagnoses should be kept in mind while dealing with tuboovarian masses in this age group. PMID:26114000

Jovian dust streams: A monitor of Io's volcanic plume activity

USGS Publications Warehouse

Kruger, H.; Geissler, P.; Horanyi, M.; Graps, A.L.; Kempf, S.; Srama, R.; Moragas-Klostermeyer, G.; Moissl, R.; Johnson, T.V.; Grun, E.

2003-01-01

Streams of high speed dust particles originate from Jupiter's moon Io. After release from Io, the particles collect electric charges in the Io plasma torus, gain energy from the co-rotating electric field of Jupiter's magnetosphere, and leave the Jovian system into interplanetary space with escape speeds over 200 km s-1. The Galileo spacecraft has continuously monitored the dust streams during 34 revolutions about Jupiter between 1996 and 2002. The observed dust fluxes exhibit large orbit-to-orbit variability due to systematic and stochastic changes. After removal of the systematic variations, the total dust emission rate of Io has been calculated. It varies between 10-3 and 10 kg s-1, and is typically in the range of 0.1 to 1 kg s-1. We compare the dust emission rate with other markers of volcanic activity on Io like large-area surface changes caused by volcanic deposits and sightings of volcanic plumes. Copyright 2003 by the American Geophysical Union.

Planetary Volcanism

NASA Technical Reports Server (NTRS)

Antonenko, I.; Head, J. W.; Pieters, C. W.

1998-01-01

The final report consists of 10 journal articles concerning Planetary Volcanism. The articles discuss the following topics: (1) lunar stratigraphy; (2) cryptomare thickness measurements; (3) spherical harmonic spectra; (4) late stage activity of volcanoes on Venus; (5) stresses and calderas on Mars; (6) magma reservoir failure; (7) lunar mare basalt volcanism; (8) impact and volcanic glasses in the 79001/2 Core; (9) geology of the lunar regional dark mantle deposits; and (10) factors controlling the depths and sizes of magma reservoirs in Martian volcanoes.

Child Care Arrangements for Toddlers and Preschoolers: Are They Different for Youngest Children?

ERIC Educational Resources Information Center

Joesch, Jutta M.; Maher, Erin J.; Durfee, Alesha

2006-01-01

Many extant studies on the use of non-parental child care are based on data from the youngest child in the household. To date, it has not been addressed whether this approach introduces bias. We present reasons why child care arrangements for youngest children may differ from those of same-age older children and examine whether the use of child…

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

USGS Publications Warehouse

McGimsey, Robert G.; Wallace, Kristi L.

1999-01-01

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

Fine crustal and uppermost mantle S-wave velocity structure beneath the Tengchong volcanic area inferred from receiver function and surface-wave dispersion: constraints on magma chamber distribution

NASA Astrophysics Data System (ADS)

Li, Mengkui; Zhang, Shuangxi; Wu, Tengfei; Hua, Yujin; Zhang, Bo

2018-03-01

The Tengchong volcanic area is located in the southeastern margin of the collision zone between the Indian and Eurasian Plates. It is one of the youngest intraplate volcano groups in mainland China. Imaging the S-wave velocity structure of the crustal and uppermost mantle beneath the Tengchong volcanic area is an important means of improving our understanding of its volcanic activity and seismicity. In this study, we analyze teleseismic data from nine broadband seismic stations in the Tengchong Earthquake Monitoring Network. We then image the crustal and uppermost mantle S-wave velocity structure by joint analysis of receiver functions and surface-wave dispersion. The results reveal widely distributed low-velocity zones. We find four possible magma chambers in the upper-to-middle crust and one in the uppermost mantle. The chamber in the uppermost mantle locates in the depth range from 55 to 70 km. The four magma chambers in the crust occur at different depths, ranging from the depth of 7 to 25 km in general. They may be the heat sources for the high geothermal activity at the surface. Based on the fine crustal and uppermost mantle S-wave velocity structure, we propose a model for the distribution of the magma chambers.

Characterization of the Etna volcanic emissions through an active biomonitoring technique (moss-bags): part 2--morphological and mineralogical features.

PubMed

Calabrese, S; D'Alessandro, W

2015-01-01

Volcanic emissions were studied at Mount Etna (Italy) by using moss-bags technique. Mosses were exposed around the volcano at different distances from the active vents to evaluate the impact of volcanic emissions in the atmosphere. Morphology and mineralogy of volcanic particulate intercepted by mosses were investigated using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). Particles emitted during passive degassing activity from the two active vents, Bocca Nuova and North East Crater (BNC and NEC), were identified as silicates, sulfates and halide compounds. In addition to volcanic particles, we found evidences also of geogenic, anthropogenic and marine spray input. The study has shown the robustness of this active biomonitoring technique to collect particles, very useful in active volcanic areas characterized by continuous degassing and often not easily accessible to apply conventional sampling techniques. Copyright © 2014 Elsevier Ltd. All rights reserved.

Head, Heart, and Hands for Our Youngest Children.

ERIC Educational Resources Information Center

Southeastern Regional Vision for Education (SERVE), Tallahassee, FL.

This document details a strategy to bring together state and community leaders in the southeastern United States to establish dialogue, set priorities, and make system-wide changes for supporting literacy for the youngest children and their families. The Head, Heart, and Hands campaign has three focal points: (1) Head--understanding research and…

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

USGS Publications Warehouse

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

2008-01-01

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

(abstract) Survey of Volcanic Hazards in the Trans Mexican Volcanic Belt

NASA Technical Reports Server (NTRS)

Abrams, M.; Siebe, C.; Macias, J.

1997-01-01

A substantial percentage of the world's population lives in areas vulnerable to the negative effects of future volcanic activity. This is especially true in Mexico, where within the Trans Mexican Volcanic Belt (TMVB) one half of the country's 90 million inhabitants live. The TMVB is a 1 000 by 200 km area, dotted with hundreds of volcanoes and volcanic centers. Most of the area has been poorly studied, and the volcanic history is largely unknown. Our approach is to combine interpretations of satellite images, field work and mapping, laboratory analysis, and age dating to elucidate the volcanic history and evaluate the potential eruptive hazards. Hazards evaluations are done in the form of risk maps.

Volcanism at Hualca Hualca Volcano, Southern Peru

NASA Astrophysics Data System (ADS)

Burkett, B.

2005-12-01

Nevado Hualca Hualca (6025m), in southern Peru, is the northernmost edifice in a north-south trending chain of 3 volcanoes that includes Ampato and the active Sabancaya stratovolcano. The oldest in the chain and considered extinct, virtually no research exists about the history of this large volcano. The summit of the volcano shows deep incision by glaciation, which from aerial photographs appears unaffected by later volcanism. Its north slope, however, possesses numerous volcanic domes, extensive lava flows with distinct levees and transverse ridges, and pyroclastic flow deposits. Deposits on the northwestern slope of Hualca Hualca include breadcrust-rich block-and-ash flows (BAF), several dacite lava flows including one with an identifiable source dome about 15km from the summit, and a sequence of small pyroclastic flow deposits with minor associated tephra. Analyses of these deposits show a restricted range of compositions (63-68 wt% SiO2). The PF sequence has an upward decrease in SiO2 and basaltic andesite (56 wt% SiO2) inclusions occur in the uppermost PFs. Principal phenocrysts include plagioclase, biotite, hornblende, clinopyroxene, orthopyroxene, Fe-Ti oxides, and sphene. Fine grained, angular to sub-rounded magmatic enclaves occur within the breadcrust-rich BAF deposits and the youngest lava flow. They are characterized by randomly oriented acicular hornblende, lack of chilled margins, and a few voids indicative of a quench texture. Plagioclase crystals with "dusty" rims or cores present in most of the deposits suggest resorption caused by magma recharge. These features imply a stratified magma chamber subject to magma recharge events and mingling to produce the quench texture enclaves. Chemical analyses indicate that the volcanic products result from magma mixing processes; the basaltic andesite inclusions may represent the mafic end-member of the mixing process. The physical characteristics of the deposits and chemical analyses were compared with data

The response of tropical cyclone activity to tropospheric aerosols, greenhouse gases and volcanic eruptions

NASA Astrophysics Data System (ADS)

Camargo, S. J.; Sobel, A. H.; Polvani, L. M.; Emanuel, K.; Previdi, M. J.

2017-12-01

Previous work has shown that aerosol cooling reduces tropical cyclone (TC) potential intensity (PI) more strongly than greenhouse gas warming increases it. This has the consequence that PI shows only small increases in simulations of the historical period despite considerable global warming over that period. We use CMIP5 models, as well as offline radiative kernels, to better understand this result. The outsize effect of aerosol forcing is a consequence of the fact that tropospheric aerosols act in the shortwave while greenhouse gases act in the longwave. Shortwave forcing has a greater impact on PI than does longwave, because of the differences in the response of the surface energy budget to the direct, temperature-independent component of the forcing. Shortwave forcing mainly drives the climate system in the surface, while greenhouse gases do so at the top of the atmosphere, so that net longwave flux associated with a temperature change can be small, especially at high temperature. Our kernel results also indicate that the temperature-dependent longwave feedback component is also greater by approximately a factor of two for the shortwave than the longwave forcing. Recent papers using observations and proxy reconstructions suggested a reduction of frequency, duration and intensity of Atlantic TCs in the years following volcanic eruptions. Observations show no significant reduction of TC activity in the first season after three large volcanic eruptions in the 20th Century, with the exception of the North Atlantic. The response to these volcanic eruptions cannot be separated from the coinciding El Niño events either in observations or in reanalysis. Both the NCAR Large Ensemble and CMIP5 models show a strong reduction in the PI following large volcanic eruptions. But, given that the models response to volcanic aerosols is known to be too strong, when a bias correction is considered, the PI signal after the volcanic eruptions becomes much smaller. Furthermore, there

Search for possible relationship between volcanic ash particles and thunderstorm lightning activity

NASA Astrophysics Data System (ADS)

Várai, A.; Vincze, M.; Lichtenberger, J.; Jánosi, I. M.

2011-12-01

Explosive volcanic eruptions that eject columns of ash from the crater often generate lightning discharges strong enough to be remotely located by very low frequency radio waves. A fraction of volcanic ash particles can stay and disperse long enough to have an effect on weather phenomena days later such as thunderstorms and lightnings. In this work we report on lightning activity analysis over Europe following two recent series of volcanic eruptions in order to identify possible correlations between ash release and subsequent thunderstorm flash frequency. Our attempts gave negative results which can be related to the fact that we have limited information on local atmospheric variables of high enough resolution, however lightning frequency is apparently determined by very local circumstances.

The cause and source of melting for the most recent volcanism in Tibet: A combined geochemical and geophysical perspective

NASA Astrophysics Data System (ADS)

Wei, Feixiang; Prytulak, Julie; Xu, Jiandong; Wei, Wei; Hammond, James O. S.; Zhao, Bo

2017-09-01

We investigate the youngest volcanic activity on the Tibetan Plateau by combining observations from petrologic, geochemical and seismic tomography studies. Recent (from 2.80 Ma to present) post-collisional potassium-rich lavas from the Ashikule Volcanic Basin (AVB) in northwestern Tibet are characterised by remarkably enriched light rare earth elements (LREE) relative to heavy rare earth elements (HREE), and enriched large ion lithophile element (LILE) relative to high field strength elements (HFSE). Strontium and neodymium isotopic compositions are surprisingly restricted, and show little evidence for mixing or crustal contamination, despite the thick crust upon which they are erupted. Geochemical characteristics indicate a homogeneous source, highly enriched in trace elements, which is most consistent with derivation from long-lived subcontinental lithospheric mantle (SCLM). P-wave anisotropy tomography documents a gap between the north-subducting Indian slab and south-subducting Tarim slab directly beneath the AVB. We propose that volcanism in northwestern Tibet is associated with the progressive closure of this gap, during which shear heating of the SCLM can generate localised melting, with deep-seated faults providing a mechanism for erupted lavas to escape large-scale crustal contamination and fractionation in magma reservoirs. Thus, shear heating may provide an explanation for the restricted range of radiogenic isotope compositions from a SCLM source that should be, by its nature, heterogeneous on a large scale.

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

USGS Publications Warehouse

McGimsey, Robert G.; Neal, Christina A.

1996-01-01

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

Geochronology of the late Pliocene to recent volcanic activity in the Payenia back-arc volcanic province, Mendoza Argentina

NASA Astrophysics Data System (ADS)

Gudnason, Jónas; Holm, Paul Martin; Søager, Nina; Llambías, Eduardo J.

2012-08-01

Eighteen samples originating from monogenetic cones and larger complexes in the back-arc Payenia volcanic province, in Mendoza Argentina, have been dated by the 40Ar/39Ar method. Groundmass and plagioclase separates give plateau ages, ranging from 20.7 ± 0.5 to 0.06 ± 0.02 Ma. Payenia has been divided into six subfields based on the new and literature radiometric ages: Payún Matrú, Río Colorado, Llancanelo, and Nevado volcanic fields, the Northern segment and the Andes retro-arc group. Fifteen samples are younger than 2.83 Ma and show correlation between geographic position and age. Eruption centres younger than 0.5 Ma are concentrated to the west of 69° W with few exceptions among new and literature data. This westward shift of activity supports the rollback theory for the subducting Nazca plate since the late Pliocene. Furthermore, a northward progression of volcanism on the San Rafael block from 2.8 Ma to around 0.5 Ma is recognized. We conclude that rollback was initiated in the southern part of Payenia in the early Pliocene and progressed >200 km northwards during the Pliocene-Pleistocene period creating conditions for hydrous magma generation beneath the eastern part of Payenia. The long lived activity of the Payún Matrú complex is ascribed to the presence of a thermal anomaly in the underlying asthenosphere which could be plume-like.

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

USGS Publications Warehouse

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

2015-08-14

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

Sensitivity to volcanic field boundary

NASA Astrophysics Data System (ADS)

Runge, Melody; Bebbington, Mark; Cronin, Shane; Lindsay, Jan; Rashad Moufti, Mohammed

2016-04-01

Volcanic hazard analyses are desirable where there is potential for future volcanic activity to affect a proximal population. This is frequently the case for volcanic fields (regions of distributed volcanism) where low eruption rates, fertile soil, and attractive landscapes draw populations to live close by. Forecasting future activity in volcanic fields almost invariably uses spatial or spatio-temporal point processes with model selection and development based on exploratory analyses of previous eruption data. For identifiability reasons, spatio-temporal processes, and practically also spatial processes, the definition of a spatial region is required to which volcanism is confined. However, due to the complex and predominantly unknown sub-surface processes driving volcanic eruptions, definition of a region based solely on geological information is currently impossible. Thus, the current approach is to fit a shape to the known previous eruption sites. The class of boundary shape is an unavoidable subjective decision taken by the forecaster that is often overlooked during subsequent analysis of results. This study shows the substantial effect that this choice may have on even the simplest exploratory methods for hazard forecasting, illustrated using four commonly used exploratory statistical methods and two very different regions: the Auckland Volcanic Field, New Zealand, and Harrat Rahat, Kingdom of Saudi Arabia. For Harrat Rahat, sensitivity of results to boundary definition is substantial. For the Auckland Volcanic Field, the range of options resulted in similar shapes, nevertheless, some of the statistical tests still showed substantial variation in results. This work highlights the fact that when carrying out any hazard analysis on volcanic fields, it is vital to specify how the volcanic field boundary has been defined, assess the sensitivity of boundary choice, and to carry these assumptions and related uncertainties through to estimates of future activity and

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

USGS Publications Warehouse

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

2014-01-01

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

Age progressive volcanism opposite Nazca plate motion: Insights from seamounts on the northeastern margin of the Galapagos Platform

NASA Astrophysics Data System (ADS)

Sinton, Christopher W.; Hauff, Folkmar; Hoernle, Kaj; Werner, Reinhard

2018-06-01

We present new geochemical and 40Ar/39Ar analyses from seven seamounts located off the northeastern margin of the shallow Galápagos Platform. Initial volcanism at 5.2 Ma created a small island (Pico) over the current location of the hotspot with geochemically enriched lavas. There is no further record of magmatism in the study area until 3.8 to 2.5 Ma, during which four roughly conical volcanoes (Sunray, Grande, Fitzroy, and Beagle) formed through eruption of lavas derived from a depleted mantle source. Sunray, Fitzroy, and Grande were islands that existed for 3 m.y. ending with the submergence of Fitzroy at 0.5 Ma. The youngest seamounts, Largo and Iguana, do not appear to have been subaerial and were active at 1.3 Ma and 0.5 Ma, respectively, with the style of edifice changing from the previous large cones to E-W elongate, composite structures. The progression of magmatism suggests that Pico erupted near 91.5°W near the location of the Galápagos plume while the others formed well east of the plume center. If the locations of initial volcanism are calculated using the eastward velocity of the Nazca plate, there appears to be a progression of younger volcanism toward the east, opposite what would be expected from a fixed mantle plume source. The rate that initial volcanism moves eastward is close to the plate velocity. A combination of higher temperature and geochemical enrichment of the thickened lithosphere of the Galápagos platform could have provided a viscosity gradient at the boundary between the thick lithosphere and the thinner oceanic lithosphere to the northeast. As this boundary moved eastward with the Nazca plate, it progressively triggered shear-driven mantle upwelling and volcanism.

Marine tephrochronology of the Mt. Edgecumbe volcanic field, southeast Alaska, USA

USGS Publications Warehouse

Addison, Jason A.; Beget, James E.; Ager, Thomas A.; Finney, Bruce P.

2010-01-01

The Mt. Edgecumbe Volcanic Field (MEVF), located on Kruzof Island near Sitka Sound in southeast Alaska, experienced a large multiple-stage eruption during the last glacial maximum (LGM)-Holocene transition that generated a regionally extensive series of compositionally similar rhyolite tephra horizons and a single well-dated dacite (MEd) tephra. Marine sediment cores collected from adjacent basins to the MEVF contain both tephra-fall and pyroclastic flow deposits that consist primarily of rhyolitic tephra and a minor dacitic tephra unit. The recovered dacite tephra correlates with the MEd tephra, whereas many of the rhyolitic tephras correlate with published MEVF rhyolites. Correlations were based on age constraints and major oxide compositions of glass shards. In addition to LGM-Holocene macroscopic tephra units, four marine cryptotephras were also identified. Three of these units appear to be derived from mid-Holocene MEVF activity, while the youngest cryptotephra corresponds well with the White River Ash eruption at not, vert, similar 1147 cal yr BP. Furthermore, the sedimentology of the Sitka Sound marine core EW0408-40JC and high-resolution SWATH bathymetry both suggest that extensive pyroclastic flow deposits associated with the activity that generated the MEd tephra underlie Sitka Sound, and that any future MEVF activity may pose significant risk to local population centers.

The nephelinitic-phonolitic volcanism of the Trindade Island (South Atlantic Ocean): Review of the stratigraphy, and inferences on the volcanic styles and sources of nephelinites

NASA Astrophysics Data System (ADS)

Pires, Gustavo Luiz Campos; Bongiolo, Everton Marques

2016-12-01

Trindade Island is located in the South Atlantic Ocean, 1170 km from the Brazilian coast, and represents the eastern end of the E-W Vitória-Trindade Chain. It shows the youngest plume-induced (ca. 3.7 to <0.17 Ma) subaerial volcanism on the South American plate, associated with the Trindade plume activity. Almeida (1961) recognized five volcanogenic successions at Trindade (in decreasing age): the Trindade Complex (TC, >2.4 Ma) and the Desejado (DF, ∼2.4 to 1.5 Ma), Morro Vermelho (MV, <0.17 Ma), Valado (VF, no age) and Paredão (PF, no age) formations, composed of effusive-pyroclastic deposits and subvolcanic intrusions associated with nephelinite-phonolite volcanic episodes. We revised the original Almeida's (1961) stratigraphy with additional field work and petrography to recognize eruptive styles and processes within the nephelinite-phonolite volcanism. Also, available geochemical databases were used to improve the stratigraphic correlation between nephelinites from different units and to characterize their mantle sources. The nephelinitic volcanism may represent Strombolian and Hawaiian-type activity of low viscosity and volatile-rich lavas interlayered with pyroclastic successions (fall-out deposits). Phonolitic deposits record explosive Vulcanian-style episodes of volatile-rich and higher-viscosity lavas interlayered with pyroclastic deposits (mostly pyroclastic flows). Geochemical data allowed the individualization of nephelinites as follows: (1) MV olivine-rich nephelinites and all olivine-free varieties are low K2O/Na2O, K2O/TiO2 and intermediate CaO/Al2O3 that may be derived from N-MORB and HIMU mantle components; (2) the VF olivine-rich nephelinites have high K2O/Na2O, K2O/TiO2 and CaO/Al2O3 that indicates both EM and HIMU mantle sources and; (3) the PF olivine-rich nephelinites show high K2O/TiO2 similar to those from VF, and intermediate CaO/Al2O3 as nephelinites from MV rocks, suggesting a mixed source with EM + HIMU > N-MORB components. We

Volcanoes of the passive margin: The youngest magmatic event in eastern North America

USGS Publications Warehouse

Mazza, Sarah E; Gazel, Esteban; Johnson, Elizabeth A; Kunk, Michael J.; McAleer, Ryan J.; Spotila, James A; Bizimis, Michael; Coleman, Drew S

2014-01-01

The rifted eastern North American margin (ENAM) provides important clues to the long-term evolution of continental margins. An Eocene volcanic swarm exposed in the Appalachian Valley and Ridge Province of Virginia and West Virginia (USA) contains the youngest known igneous rocks in the ENAM. These magmas provide the only window into the most recent deep processes contributing to the postrift evolution of this margin. Here we present new 40Ar/39Ar ages, geochemical data, and radiogenic isotopes that constrain the melting conditions and the timing of emplacement. Modeling of the melting conditions on primitive basalts yielded an average temperature and pressure of 1412 ± 25 °C and 2.32 ± 0.31 GPa, corresponding to a mantle potential temperature of ∼1410 °C, suggesting melting conditions slightly higher than average mantle temperatures beneath mid-ocean ridges. When compared with magmas from Atlantic hotspots, the Eocene ENAM samples share isotopic signatures with the Azores and Cape Verde. This similarity suggests the possibility of a large-scale dissemination of similar sources in the upper mantle left over from the opening of the Atlantic Ocean. Asthenosphere upwelling related to localized lithospheric delamination is a possible process that can explain the intraplate signature of these magmas that lack evidence of a thermal anomaly. This process can also explain the Cenozoic dynamic topography and evidence of rejuvenation of the central Appalachians.

Volcanism in Eastern Africa

NASA Technical Reports Server (NTRS)

Cauthen, Clay; Coombs, Cassandra R.

1996-01-01

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

Elemental characterization of Mt. Sinabung volcanic ash, Indonesia by Neutron Activation Analysis

NASA Astrophysics Data System (ADS)

Kusmartini, I.; Syahfitri, W. Y. N.; Kurniawati, S.; Lestiani, D. D.; Santoso, M.

2017-06-01

Mount Sinabung is a volcano located in North Sumatera, Indonesia which has been recorded not erupted since 1600. However in 2013 it has been erupted and cause of black thick smog, rain sand and volcanic ash. Volcanic ash containing trace elements material that can be utilized in various applications but still has potential danger of heavy metals. In order to obtain an elemental composition data of volcanic ash, the characterization of volcanic ash were carried out using Neutron Activation Analysis. The volcanic ash was taken from Mt. Sinabung eruption. Samples were irradiated at the rabbit system in the reactor G.A Siwabessy facilities with neutron flux ˜ 1013 n.cm-2.s-1 and then counted using HPGe detector. Method validation was carried out by SRM NIST Coal Fly Ash 1633b and NIST 2711a Montana II Soil with recovery values were in the range of 96-108% and 95-106% respectively. The results showed that major elements; Al, Na, Ca and Fe, concentrations were 8.7, 1.05, 2.98 and 7.44 %, respectively, minor elements K, Mg, Mn, Ti, V and Zn were 0.87%, 0.78%, 0.18%, 0.62%, 197.13 ppm and 109.35 ppm, respectively, heavy metals; As, Cr, Co and Sb, contents were 4.48, 11.75, 17.13 and 0.35 ppm, respectively while rare earth elements such as Ce, Eu, La, Nd, Sm, Yb were 45.33, 1.22, 19.63, 20.34, 3.86, and 2.57 ppm respectively. The results of the elemental contents of volcanic ash that has been obtained can be used as the scientific based data for volcanic material utilization by considering the economic potential of elements contained and also the danger of the heavy metals content.

Dinasour extinction and volcanic activity

NASA Astrophysics Data System (ADS)

Gledhill, J. A.

There is at present some controversy about the reason for the mass extinction of dinosaurs and other forms of life at the end of the Cretaceous. A suggestion by Alvarez et al. [1980] that this was due to the collision of the earth with a meteorite 10 km or so in diameter has excited considerable interest [Silver and Schultz, 1982] and also some criticism [Stanley, 1984]. A recent publication [Wood, 1984] describing the catastrophic effects of a relatively minor lava flow in Iceland suggests that intense volcanic activity could have played a large part in the extinctions. In this letter it is pointed out that the Deccan lava flows in India took place in the appropriate time and may well have been of sufficient magnitude to be a major factor in the Cretaceous-Tertiary (C-T) boundary catastrophe.

Cenozoic volcanic rocks of Saudi Arabia

USGS Publications Warehouse

Coleman, R.G.; Gregory, R.T.; Brown, G.F.

2016-01-01

The historical record of volcanic activity in Saudi Arabia suggests that volcanism is dormant. The harrats should be evaluated for their potential as volcanic hazards and as sources of geothermal energy. The volcanic rocks are natural traps for groundwater; thus water resources for agriculture may be significant and should be investigated.

Time analysis of volcanic activity on Io by means of plasma observations

NASA Technical Reports Server (NTRS)

Mekler, Y.; Eviatar, A.

1980-01-01

A model of Io volcanism in which the probability of activity obeys a binomial distribution is presented. Observed values of the electron density obtained over a 3-year period by ground-based spectroscopy are fitted to such a distribution. The best fit is found for a total number of 15 volcanoes with a probability of individual activity at any time of 0.143. The Pioneer 10 ultraviolet observations are reinterpreted as emissions of sulfur and oxygen ions and are found to be consistent with a plasma much less dense than that observed by the Voyager spacecraft. Late 1978 and the first half of 1979 are shown to be periods of anomalous volcanicity. Rapid variations in electron density are related to enhanced radial diffusion.

East Pacific rise at 21°N: the volcanic, tectonic, and hydrothermal processes of the central axis

USGS Publications Warehouse

Ballard, Richard D.; Francheteau, Jean; Juteau, Tierre; Rangan, Claude; Normark, William

1981-01-01

Photographs obtained by the ANGUS survey system at 21°N reveal many similarities to the geological processes delineated at other spreading centers and in particular those observed in the Galapagos Rift at 86°W. The region of recent volcanism is restricted to a narrow zone (Zone 1) approximately 1 km wide. This suggests that the width of the magma chamber feeding these flows is also narrow at the top. Variations in sediment cover are used to subdivide the flows within Zone 1 into three sheet-flow/pillow-flow pairs. The youngest pair appears to have erupted form a linear fissure 8 km long running parallel to the valley axis. This fissure is part of a larger en echelon pattern of eruptive fissures. Active hydrothermal vents associated with the youngest flows are situated directly above the apparent eruptive fissure. The high (350°C) temperature for some of the fluids exiting from the vents suggests a highly restricted circulation system involving, at times, little to no mixing with cold seawater. The lava terrain in the remainder of Zone 1 and bordering regions is characterized by extensive fracturing, further suggesting a narrow upper dimension to the magma chamber and also that subsurface hydrothermal deposition of massive sulfides may lead to a reduction in the mixing processes.

East Pacific Rise at 21 °N: The volcanic, tectonic, and hydrothermal processes of the central axis

USGS Publications Warehouse

Ballard, Richard D.; Francheteau, Jean; Juteau, Tierre; Rangan, Claude; Normark, William R.

1981-01-01

Photographs obtained by the ANGUS survey system at 21°N reveal many similarities to the geological processes delineated at other spreading centers and in particular those observed in the Galapagos Rift at 86°W. The region of recent volcanism is restricted to a narrow zone (Zone l) approximately l km wide. This suggests that the width of the magma chamber feeding these flows is also narrow at the top. Variations in sediment cover are used to subdivide the flows within Zone 1 into three sheet-flow/pillow-flow pairs. The youngest pair appears to have erupted form a linear fissure 8 km long running parallel to the valley axis. This fissure is part of a larger en echelon pattern of eruptive fissures. Active hydrothermal vents associated with the youngest flows are situated directly above the apparent eruptive fissure. The high (350°C) temperature for some of the fluids exiting from the vents suggests a highly restricted circulation system involving, at times, little to no mixing with cold seawater. The lava terrain in the remainder of Zone l and bordering regions is characterized by extensive fracturing, further suggesting a narrow upper dimension to the magma chamber and also that subsurface hydrothermal deposition of massive sulfides may lead to a reduction in the mixing processes.

East Pacific rise at 21°N: The volcanic, tectonic, and hydrothermal processes of the central axis

NASA Astrophysics Data System (ADS)

Ballard, Robert D.; Francheteau, Jean; Juteau, Tierre; Rangan, Claude; Normark, William

1981-09-01

Photographs obtained by the ANGUS survey system at 21°N reveal many similarities to the geological processes delineated at other spreading centers and in particular those observed in the Galapagos Rift at 86°W. The region of recent volcanism is restricted to a narrow zone (Zone 1) approximately 1 km wide. This suggests that the width of the magma chamber feeding these flows is also narrow at the top. Variations in sediment cover are used to subdivide the flows within Zone 1 into three sheet-flow/pillow-flow pairs. The youngest pair appears to have erupted form a linear fissure 8 km long running parallel to the valley axis. This fissure is part of a larger en echelon pattern of eruptive fissures. Active hydrothermal vents associated with the youngest flows are situated directly above the apparent eruptive fissure. The high (350°C) temperature for some of the fluids exiting from the vents suggests a highly restricted circulation system involving, at times, little to no mixing with cold seawater. The lava terrain in the remainder of Zone 1 and bordering regions is characterized by extensive fracturing, further suggesting a narrow upper dimension to the magma chamber and also that subsurface hydrothermal deposition of massive sulfides may lead to a reduction in the mixing processes.

SYSTHESIS OF VOLCANISM STUDIES FOR THE YUCCA MOUNTAIN SITE CHARACTERIZATION PROJECT

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

Perry, F. V.; Crowe, G. A.; Valentine, G. A.

1997-09-23

This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The hazard of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certaintymore » but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The distribution of Pliocene and Quaternary basaltic volcanic centers is evaluated with respect to tectonic models for detachment, caldera, regional and local rifting, and the Walker Lane structural zone. Geophysical data are described for the YMR and are used as an aid to understand the distribution of past basaltic volcanic centers and possible future magmatic processes. Chapter 4 discusses the petrologic and geochemical features of basaltic volcanism in the YMR, the southern Great Basin and the

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

USGS Publications Warehouse

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

2014-01-01

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

Statistical Analysis of Time-Series from Monitoring of Active Volcanic Vents

NASA Astrophysics Data System (ADS)

Lachowycz, S.; Cosma, I.; Pyle, D. M.; Mather, T. A.; Rodgers, M.; Varley, N. R.

2016-12-01

Despite recent advances in the collection and analysis of time-series from volcano monitoring, and the resulting insights into volcanic processes, challenges remain in forecasting and interpreting activity from near real-time analysis of monitoring data. Statistical methods have potential to characterise the underlying structure and facilitate intercomparison of these time-series, and so inform interpretation of volcanic activity. We explore the utility of multiple statistical techniques that could be widely applicable to monitoring data, including Shannon entropy and detrended fluctuation analysis, by their application to various data streams from volcanic vents during periods of temporally variable activity. Each technique reveals changes through time in the structure of some of the data that were not apparent from conventional analysis. For example, we calculate the Shannon entropy (a measure of the randomness of a signal) of time-series from the recent dome-forming eruptions of Volcán de Colima (Mexico) and Soufrière Hills (Montserrat). The entropy of real-time seismic measurements and the count rate of certain volcano-seismic event types from both volcanoes is found to be temporally variable, with these data generally having higher entropy during periods of lava effusion and/or larger explosions. In some instances, the entropy shifts prior to or coincident with changes in seismic or eruptive activity, some of which were not clearly recognised by real-time monitoring. Comparison with other statistics demonstrates the sensitivity of the entropy to the data distribution, but that it is distinct from conventional statistical measures such as coefficient of variation. We conclude that each analysis technique examined could provide valuable insights for interpretation of diverse monitoring time-series.

2015 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

USGS Publications Warehouse

Dixon, James P.; Cameron, Cheryl E.; Iezzi, Alexandra M.; Wallace, Kristi

2017-09-28

The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 14 volcanic centers in Alaska during 2015. The most notable volcanic activity consisted of continuing intermittent ash eruptions from Cleveland and Shishaldin volcanoes in the Aleutian Islands. Two eruptive episodes, at Veniaminof and Pavlof, on the Alaska Peninsula ended in 2015. During 2015, AVO re-established the seismograph network at Aniakchak, installed six new broadband seismometers throughout the Aleutian Islands, and added a Multiple component Gas Analyzer System (MultiGAS) station on Augustine.

Observing Active Volcanism on Earth and Beyond With an Autonomous Science Investigation Capability

NASA Astrophysics Data System (ADS)

Davies, A. G.; Mjolsness, E. D.; Fink, W.; Castano, R.; Park, H. G.; Zak, M.; Burl, M. C.

2001-12-01

Operational constraints imposed by restricted downlink and long communication delays make autonomous systems a necessity for exploring dynamic processes in the Solar System and beyond. Our objective is to develop an onboard, modular, automated science analysis tool that will autonomously detect unexpected events, identify rare events at predicted sites, quantify the processes under study, and prioritize the science data and analyses as they are collected. A primary target for this capability is terrestrial active volcanism. Our integrated, science-driven command and control package represents the next stage of the automatic monitoring of volcanic activity pioneered by GOES. The resulting system will maximize science return from day-to-day instrument use and provide immediate reaction to capture the fullest information from infrequent events. For example, a sensor suite consisting of a Galileo-like multi-filter visible wavelength camera and an infrared spectrometer, can acquire high-spatial resolution data of eruptions of lava and volcanic plumes and identify large concentrations of volcanic SO2. After image/spectrum formation, software is applied to the data which is capable of change detection (in the visible and infrared), feature identification (both in imagery and spectra), and novelty detection. In this particular case, the latter module detects change in the parameter space of an advanced multi-component black-body volcanic thermal emission model by means of a novel technique called the "Grey-Box" method which analyzes time series data through a combination of deterministic and stochastic models. This approach can be demonstrated using data obtained by the Galileo spacecraft of ionian volcanism. The system autonomously identifies the most scientifically important targets and prioritizes data and analyses for return. All of these techniques have been successfully demonstrated in laboratory experiments, and are ready to be tested in an operational environment

Evidence of volcanic and glacial activity in Chryse and Acidalia Planitiae, Mars

USGS Publications Warehouse

Martinez-Alonso, Sara; Mellon, Michael T.; Banks, Maria E.; Keszthelyi, Laszlo P.; McEwen, Alfred S.

2011-01-01

Chryse and Acidalia Planitiae show numerous examples of enigmatic landforms previously interpreted to have been influenced by a water/ice-rich geologic history. These landforms include giant polygons bounded by kilometer-scale arcuate troughs, bright pitted mounds, and mesa-like features. To investigate the significance of the last we have analyzed in detail the region between 60°N, 290°E and 10°N, 360°E utilizing HiRISE (High Resolution Imaging Science Experiment) images as well as regional-scale data for context. The mesas may be analogous to terrestrial tuyas (emergent sub-ice volcanoes), although definitive proof has not been identified. We also report on a blocky unit and associated landforms (drumlins, eskers, inverted valleys, kettle holes) consistent with ice-emplaced volcanic or volcano-sedimentary flows. The spatial association between tuya-like mesas, ice-emplaced flows, and further possible evidence of volcanism (deflated flow fronts, volcanic vents, columnar jointing, rootless cones), and an extensive fluid-rich substratum (giant polygons, bright mounds, rampart craters), allows for the possibility of glaciovolcanic activity in the region.Landforms indicative of glacial activity on Chryse/Acidalia suggest a paleoclimatic environment remarkably different from today's. Climate changes on Mars (driven by orbital/obliquity changes) or giant outflow channel activity could have resulted in ice-sheet-related landforms far from the current polar caps.

Relation of compositions of deep fluids in geothermal activity of Pleistocene-Holocene volcanic fields of Lesser Caucasus

NASA Astrophysics Data System (ADS)

Meliksetian, Khachatur; Lavrushin, Vassily; Shahinyan, Hrach; Aidarkozhina, Altin; Navasardyan, Gevorg; Ermakov, Alexander; Zakaryan, Shushan; Prasolov, Edward; Manucharyan, Davit; Gyulnazaryan, Shushan; Grigoryan, Edmond

2017-04-01

It is widely accepted, that geothermal activity in the conductive heat flow processes, such as volcanism and hydrothermal activity, is manifestation of the thermal mass transfer process in the Earth's crust, where geothermal and geochemical processes are closely connected. Therefore, geochemistry and isotope compositions of thermal mineral waters within and on periphery of volcanic clusters may represent key indicators for better understanding of geothermal activity in geodynamically active zones. Geochemical features of heat and mass transport in hydrothermal systems related to active volcanic and fault systems in continental collision related orogenic elevated plateaus such as Anatolian-Armenian-Iranian highlands are still poorly understood. In this contribution we attempt to fill these gaps in our knowledge of relations of geochemical and geothermal processes in collision zones. We present new data on chemical compositions, trace element geochemistry of thermal waters of Lesser Caucasus, (Armenia) as well as isotope analysis of free gases such as {}3He/{}4He, {}40Ar/{}36Ar, δ{}13?(CO{}2), nitrogen δ{}15N(N{}2) and oxygen and hydrogen isotopes in water phases (δD, δ{}18O). To reveal some specific features of formation of fluid systems related to thermal activity in the areas of collision related active volcanism and active geodynamics a complex geochemical (SiO{}2, K-Na, Na-Li, Li-Mg) and isotope geothermometers (δ{}18O(CaCO{}3) - δ{}18O(H{}2O)) were applied. The distribution of δ{}13?(??{}2) values in free gases of mineral waters of Armenia demonstrates that gases related to Quaternary volcanic fields are characterized by relatively light δ{}13?(CO{}2) values close to mantle derived gases, while on periphery of volcanic systems relatively heavy values of δ{}13?(CO{}2) indicate strong influence of metamorphic and sedimentary derived carbon dioxide. Distribution of nitrogen isotopes δ{}15N(N{}2) demonstrate an inverse correlation with δ{}13?(CO{}2

Chapter 8. Industrial mineral extraction and geothermal exploration

Treesearch

Thomas Merlan

2007-01-01

The Valles Caldera is the result of the youngest major volcanic episode in the creation of the central Jémez volcanic field. This geological feature is a diverse suite of basaltic through rhyolitic rocks, which erupted from some time less than 13 million years ago to no later than .13 million years ago. It represents some of the greatest volcanic activity documented in...

Connecting Io's volcanic activity to the Io plasma torus: comparison of Galileo/NIMS volcanic and ground-based torus observations

NASA Astrophysics Data System (ADS)

Magalhaes, F. P.; Lopes, R. M. C.; Rathbun, J. A.; Gonzalez, W. D.; Morgenthaler, J. P.; Echer, E.; Echer, M. P. D. S.

2015-12-01

Io, the innermost of the Jupiter's four Galilean moons, is a remarkable object in the Solar System, due to its intense and energetic volcanic activity. The volcanic sulfur and oxygen in Io's tenuous atmosphere escapes forming an extended neutral cloud around Io and Jupiter. Subsequently, by ionization and pickup ions, a ring of charged particles encircling Jupiter is created, forming the Io plasma torus. Considering this scenario, it is reasonable to expect that the Io plasma torus should be affected by changes in Io's volcanism. Interactions between Io and the Jovian environment is unique and yet not very well understood. Here we present two sets of observations. One from the Galileo Near-Infrared Imaging Spectrograph (NIMS) instrument, which obtained spectral image cubes between 0.7 and 5.2 microns. The other dataset is from ground-based observations of the [SII] 6731 Å emission lines from the Io plasma torus, obtained at McMath-Pierce Solar Telescope, at Kitt Peak. Our dataset from the [SII] 6731 Å emission lines cover more years than the one from the NIMS data. The years presented in this work for a comparative study are from 1998 through 2001. Using the NIMS instrument we were able to identify which volcanoes were active and measure their level of activity. From the [SII] 6731 Å emission lines we were able to trace the densest part of the torus and also the brightness of both ansa. By comparing the results from the Galileo instrument and the ground-based observations, we are exploring how the Io plasma torus responds to large eruptions from Io. We aim with this study to help improve our understanding of this complex coupled system, Jupiter-Io.

The Plio-Quaternary Volcanic Evolution of Gran Canaria Based on new Unspiked K-Ar ages and Magnetostratigraphy

NASA Astrophysics Data System (ADS)

Guillou, H.; Carracedo, J.; Perez Torrado, F.

2003-12-01

The combined use of radioisotopic dating, magnetostratigraphy and field geology is a powerful tool to provide reliable chronological frameworks of volcanic edifices. This approach has been used to investigate the last two stages of the volcanic evolution of Gran Canaria. Fifty samples were dated using the unspiked K-Ar method and had their magnetic polarity measured both in the field and in laboratory. Ages were compared to their stratigraphic positions and magnetic polarities before accepting their validity. The unspiked K-Ar chronology constrains the timing of lateral collapses, eruption rates and the contemporaneity of different volcano-magmatic stages at Gran Canaria. Our new data set modifies significantly the previous chronological framework of Gran Canaria, especially between 4 and 2.8 Ma. Based on these new ages, we can bracket the age of the multiple lateral collapses of the Roque Nublo stratovolcano flanks between 3.5 and 3.1 Ma .This time interval corresponds to a main period of volcanic quiescence. Calculated eruptive rates during the stratovolcano edification are about 0.1 km3/kyr which is significantly lower than the published estimates. The dating also reveals that the two main last stages are not separated by a major time gap, but that the early stages of the rift forming eruption and the vanishing activity of the Roque Nublo strato-volcano were contemporaneous for at least 600 kyrs. These results support that our combined approach provides a rapid first-pass and reliable geochronology. Nevertheless, this chronology can be amplified and made more precise where necessary through detailed Ar-Ar incremental-heating methods. Samples which should be investigated using this method are the oldest and youngest K-Ar dated flows of each volcanic stage, and samples from stratigraphic sections that hold potential to study the behaviour of the earth's magnetic field during reversals (Gauss-Gilbert transition, Olduvai and Reunion events).

Volcanic Activity at Shiveluch and Plosky Tolbachik

NASA Image and Video Library

2017-12-08

On March 7, 2013 the Terra satellite passed over eastern Russia, allowing the Moderate Resolution Imaging Spectroradiometer (MODIS) flying aboard to capture volcanic activity at Shiveluch and Plosky Tolbachik, on the Kamchatka Peninsula, in eastern Russia. This image was captured at 0050 UTC. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team 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

Compilation of Disruptions to Airports by Volcanic Activity (Version 1.0, 1944-2006)

USGS Publications Warehouse

Guffanti, Marianne; Mayberry, Gari C.; Casadevall, Thomas J.; Wunderman, Richard

2008-01-01

Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. To more fully characterize the nature and scope of volcanic hazards to airports, we collected data on incidents of airports throughout the world that have been affected by volcanic activity, beginning in 1944 with the first documented instance of damage to modern aircraft and facilities in Naples, Italy, and extending through 2006. Information was gleaned from various sources, including news outlets, volcanological reports (particularly the Smithsonian Institution's Bulletin of the Global Volcanism Network), and previous publications on the topic. This report presents the full compilation of the data collected. For each incident, information about the affected airport and the volcanic source has been compiled as a record in a Microsoft Access database. The database is incomplete in so far as incidents may not have not been reported or documented, but it does present a good sample from diverse parts of the world. Not included are en-route diversions to avoid airborne ash clouds at cruise altitudes. The database has been converted to a Microsoft Excel spreadsheet. To make the PDF version of table 1 in this open-file report resemble the spreadsheet, order the PDF pages as 12, 17, 22; 13, 18, 23; 14, 19, 24; 15, 20, 25; and 16, 21, 26. Analysis of the database reveals that, at a minimum, 101 airports in 28 countries were impacted on 171 occasions from 1944 through 2006 by eruptions at 46 volcanoes. The number of affected airports (101) probably is better constrained than the number of incidents (171) because recurring disruptions at a given airport may have been lumped together or not reported by news agencies, whereas the initial disruption likely is noticed and reported and thus the airport correctly counted.

Syn- and post-eruptive volcanic processes in the Yubileinaya kimberlite pipe, Yakutia, Russia, and implications for the emplacement of South African-style kimberlite pipes

NASA Astrophysics Data System (ADS)

Kurszlaukis, S.; Mahotkin, I.; Rotman, A. Y.; Kolesnikov, G. V.; Makovchuk, I. V.

2009-11-01

The Yubileinaya kimberlite pipe, with a surface area of 59 ha, is one of the largest pipes in the Yakutian kimberlite province. The Devonian pipe was emplaced under structural control into Lower Paleozoic karstic limestone. The pipe complex consists of several smaller precursor pipes which are cut by the large, round Main pipe. While the precursor pipes show many features typical for root zones, Main pipe is younger, cuts into the precursor pipes and exposes well-bedded volcaniclastic sediments. The maximum estimated erosion since emplacement is 250 m. Open pit mapping of a 180 m thick kimberlite sequence documents the waning phases of the volcanic activity in the kimberlite pipe and the onset of its crater infill by resedimentation. Three volcanic lithofacies types can be differentiated. The deepest and oldest facies type is a massive volcaniclastic rock ("AKB") only accessible in drill core. It is equivalent to Tuffisitic Kimberlite in South African pipes and thought to be related to the main volcanic phase which was characterized by violent explosions. The overlying lithofacies type comprises primary and resedimented volcaniclastic sediments as well as rock avalanche deposits sourced from the exposed maar crater collar. It represents the onset of sedimentation onto the crater floor during the waning phase of volcanic eruptions, where primary pyroclastic deposition was contemporaneous with resedimentation from the tephra wall and the widening maar crater. Ongoing volcanic activity is also testified by the presence of a vertical feeder conduit marking the area of the last volcanic eruption clouds piercing through the diatreme. This feeder conduit is overlain by the third and youngest lithofacies type which consists mainly of resedimented volcaniclastic material and lake beds. During the sedimentation of this facies, primary volcanic activity was only minor and finally absent and resedimentation processes dominated the crater infill. The Yubileinaya pipe complex

Modelling ground deformation patterns associated with volcanic processes at the Okataina Volcanic Centre

NASA Astrophysics Data System (ADS)

Holden, L.; Cas, R.; Fournier, N.; Ailleres, L.

2017-09-01

The Okataina Volcanic Centre (OVC) is one of two large active rhyolite centres in the modern Taupo Volcanic Zone (TVZ) in the North Island of New Zealand. It is located in a complex section of the Taupo rift, a tectonically active section of the TVZ. The most recent volcanic unrest at the OVC includes the 1315 CE Kaharoa and 1886 Tarawera eruptions. Current monitoring activity at the OVC includes the use of continuous GPS receivers (cGPS), lake levelling and seismographs. The ground deformation patterns preceding volcanic activity the OVC are poorly constrained and restricted to predictions from basic modelling and comparison to other volcanoes worldwide. A better understanding of the deformation patterns preceding renewed volcanic activity is essential to determine if observed deformation is related to volcanic, tectonic or hydrothermal processes. Such an understanding also means that the ability of the present day cGPS network to detect these deformation patterns can also be assessed. The research presented here uses the finite element (FE) modelling technique to investigate ground deformation patterns associated with magma accumulation and diking processes at the OVC in greater detail. A number of FE models are produced and tested using Pylith software and incorporate characteristics of the 1315 CE Kaharoa and 1886 Tarawera eruptions, summarised from the existing body of research literature. The influence of a simple ring fault structure at the OVC on the modelled deformation is evaluated. The ability of the present-day continuous GPS (cGPS) GeoNet monitoring network to detect or observe the modelled deformation is also considered. The results show the modelled horizontal and vertical displacement fields have a number of key features, which include prominent lobe based regions extending northwest and southeast of the OVC. The results also show that the ring fault structure increases the magnitude of the displacements inside the caldera, in particular in the

Integrating science and education during an international, multi-parametric investigation of volcanic activity at Santiaguito volcano, Guatemala

NASA Astrophysics Data System (ADS)

Lavallée, Yan; Johnson, Jeffrey; Andrews, Benjamin; Wolf, Rudiger; Rose, William; Chigna, Gustavo; Pineda, Armand

2016-04-01

In January 2016, we held the first scientific/educational Workshops on Volcanoes (WoV). The workshop took place at Santiaguito volcano - the most active volcano in Guatemala. 69 international scientists of all ages participated in this intensive, multi-parametric investigation of the volcanic activity, which included the deployment of seismometers, tiltmeters, infrasound microphones and mini-DOAS as well as optical, thermographic, UV and FTIR cameras around the active vent. These instruments recorded volcanic activity in concert over a period of 3 to 9 days. Here we review the research activities and present some of the spectacular observations made through this interdisciplinary efforts. Observations range from high-resolution drone and IR footage of explosions, monitoring of rock falls and quantification of the erupted mass of different gases and ash, as well as morphological changes in the dome caused by recurring explosions (amongst many other volcanic processes). We will discuss the success of such integrative ventures in furthering science frontiers and developing the next generation of geoscientists.

Volcanic sulfur dioxide index and volcanic explosivity index inferred from eruptive volume of volcanoes in Jeju Island, Korea: application to volcanic hazard mitigation

NASA Astrophysics Data System (ADS)

Ko, Bokyun; Yun, Sung-Hyo

2016-04-01

Jeju Island located in the southwestern part of Korea Peninsula is a volcanic island composed of lavaflows, pyroclasts, and around 450 monogenetic volcanoes. The volcanic activity of the island commenced with phreatomagmatic eruptions under subaqueous condition ca. 1.8-2.0 Ma and lasted until ca. 1,000 year BP. For evaluating volcanic activity of the most recently erupted volcanoes with reported age, volcanic explosivity index (VEI) and volcanic sulfur dioxide index (VSI) of three volcanoes (Ilchulbong tuff cone, Songaksan tuff ring, and Biyangdo scoria cone) are inferred from their eruptive volumes. The quantity of eruptive materials such as tuff, lavaflow, scoria, and so on, is calculated using a model developed in Auckland Volcanic Field which has similar volcanic setting to the island. The eruptive volumes of them are 11,911,534 m3, 24,987,557 m3, and 9,652,025 m3, which correspond to VEI of 3, 3, and 2, respectively. According to the correlation between VEI and VSI, the average quantity of SO2 emission during an eruption with VEI of 3 is 2-8 × 103 kiloton considering that the island was formed under intraplate tectonic setting. Jeju Island was regarded as an extinct volcano, however, several studies have recently reported some volcanic eruption ages within 10,000 year BP owing to the development in age dating technique. Thus, the island is a dormant volcano potentially implying high probability to erupt again in the future. The volcanoes might have explosive eruptions (vulcanian to plinian) with the possibility that SO2 emitted by the eruption reaches stratosphere causing climate change due to backscattering incoming solar radiation, increase in cloud reflectivity, etc. Consequently, recommencement of volcanic eruption in the island is able to result in serious volcanic hazard and this study provides fundamental and important data for volcanic hazard mitigation of East Asia as well as the island. ACKNOWLEDGMENTS: This research was supported by a grant [MPSS

Diffuse Helium Emission as a Precursory Sign of Volcanic Unrest

NASA Astrophysics Data System (ADS)

Padron, E.; Perez, N.; Hernandez Perez, P. A.; Sumino, H.; Melian Rodriguez, G.; Barrancos, J.; Nolasco, D.; Padilla, G.; Dionis, S.; Rodriguez, F.; Hernandez, I.; Calvo, D.; Peraza, M.; Nagao, K.

2012-12-01

Since July 16, 2011, an anomalous seismicity at El Hierro island, the youngest and smallest of the Canary Islands, was recorded by IGN seismic network. After the occurrence of more than 10,000 seismic events, volcanic tremor was recorded since 05:15 of the October 10, by all of the seismic stations on the island, with highest amplitudes recorded in the southernmost station. During the afternoon of October 12 a large light-green coloured area was observed in the sea to the souht of La Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. As part of the volcanic surveillance of the island, the Instituto Volcanologico de Canarias (INVOLCAN) geochemical monitoring program is carrying out diffuse helium surveys on the surface environment of El Hierro (soil atmosphere). This nobel gas has been investigated because it has been considered an almost ideal geochemical indicator because it is chemically inert, physically stable, nonbiogenic, sparingly soluble in water under ambient conditions and almost non-adsorbable. At each survey, 600 sampling sites covering the whole island and following an homogeneous distribution are selected for helium measurements in the soil gases, The helium concentration gradients with respect to its value on air (5.24 ppm) allow us to estimate a pure diffusive emission rate of helium throughout the island. The first survey was carried out on the summer of 2003, when the island was on a quiescence period. At this survey, the amount of helium released by the volcanic system of El Hierro was estimated in 6 kg/d. Since the beginning of the seismic unrest, 13 helium emission surveys have been carried out. The helium emission rate has shown an excellent agreement with the evolution of the volcanic crisis of the island, reaching 30 kg

Monitoring volcanic activity using correlation patterns between infrasound and ground motion

NASA Astrophysics Data System (ADS)

Ichihara, M.; Takeo, M.; Yokoo, A.; Oikawa, J.; Ohminato, T.

2012-02-01

This paper presents a simple method to distinguish infrasonic signals from wind noise using a cross-correlation function of signals from a microphone and a collocated seismometer. The method makes use of a particular feature of the cross-correlation function of vertical ground motion generated by infrasound, and the infrasound itself. Contribution of wind noise to the correlation function is effectively suppressed by separating the microphone and the seismometer by several meters because the correlation length of wind noise is much shorter than wavelengths of infrasound. The method is applied to data from two recent eruptions of Asama and Shinmoe-dake volcanoes, Japan, and demonstrates that the method effectively detects not only the main eruptions, but also minor activity generating weak infrasound hardly visible in the wave traces. In addition, the correlation function gives more information about volcanic activity than infrasound alone, because it reflects both features of incident infrasonic and seismic waves. Therefore, a graphical presentation of temporal variation in the cross-correlation function enables one to see qualitative changes of eruptive activity at a glance. This method is particularly useful when available sensors are limited, and will extend the utility of a single microphone and seismometer in monitoring volcanic activity.

Short-lived and discontinuous intraplate volcanism in the South Pacific: Hot spots or extensional volcanism?

NASA Astrophysics Data System (ADS)

Koppers, Anthony A. P.; Staudigel, Hubert; Pringle, Malcolm S.; Wijbrans, Jan R.

2003-10-01

South Pacific intraplate volcanoes have been active since the Early Cretaceous. Their HIMU-EMI-EMII mantle sources can be traced back into the West Pacific Seamount Province (WPSP) using plate tectonic reconstructions, implying that these distinctive components are enduring features within the Earth's mantle for, at least, the last 120 Myr. These correlations are eminent on the scale of the WPSP and the South Pacific Thermal and Isotopic Anomaly (SOPITA), but the evolution of single hot spots emerges notably more complicated. Hot spots in the WPSP and SOPITA mantle regions typically display intermittent volcanic activity, longevities shorter than 40 Myr, superposition of hot spot volcanism, and motion relative to other hot spots. In this review, we use 40Ar/39Ar seamount ages and Sr-Nd-Pb isotopic signatures to map out Cretaceous volcanism in the WPSP and to characterize its evolution with respect to the currently active hot spots in the SOPITA region. Our plate tectonic reconstructions indicate cessation of volcanism during the Cretaceous for the Typhoon and Japanese hot spots; whereas the currently active Samoan, Society, Pitcairn and Marquesas hot spots lack long-lived counterparts in the WPSP. These hot spots may have become active during the last 20 Myr only. The other WPSP seamount trails can be only "indirectly" reconciled with hot spots in the SOPITA region. Complex age distributions in the Magellan, Anewetak, Ralik and Ratak seamount trails would necessitate the superposition of multiple volcanic trails generated by the Macdonald, Rurutu and Rarotonga hot spots during the Cretaceous; whereas HIMU-type seamounts in the Southern Wake seamount trail would require 350-500 km of hot spot motion over the last 100 Myr following its origination along the Mangaia-Rurutu "hotline" in the Cook-Austral Islands. These observations, however, violate all assumptions of the classical Wilson-Morgan hot spot hypothesis, indicating that long-lived, deep and fixed mantle

Geology, geochronology, and paleogeography of the southern Sonoma volcanic field and adjacent areas, northern San Francisco Bay region, California

USGS Publications Warehouse

Wagner, David L.; Saucedo, George J.; Clahan, Kevin B.; Fleck, Robert J.; Langenheim, Victoria E.; McLaughlin, Robert J.; Sarna-Wojcicki, Andrei M.; Allen, James R.; Deino, Alan L.

2011-01-01

Recent geologic mapping in the northern San Francisco Bay region (California, USA) supported by radiometric dating and tephrochronologic correlations, provides insights into the framework geology, stratigraphy, tectonic evolution, and geologic history of this part of the San Andreas transform plate boundary. There are 25 new and existing radiometric dates that define three temporally distinct volcanic packages along the north margin of San Pablo Bay, i.e., the Burdell Mountain Volcanics (11.1 Ma), the Tolay Volcanics (ca. 10–8 Ma), and the Sonoma Volcanics (ca. 8–2.5 Ma). The Burdell Mountain and the Tolay Volcanics are allochthonous, having been displaced from the Quien Sabe Volcanics and the Berkeley Hills Volcanics, respectively. Two samples from a core of the Tolay Volcanics taken from the Murphy #1 well in the Petaluma oilfield yielded ages of 8.99 ± 0.06 and 9.13 ± 0.06 Ma, demonstrating that volcanic rocks exposed along Tolay Creek near Sears Point previously thought to be a separate unit, the Donnell Ranch volcanics, are part of the Tolay Volcanics. Other new dates reported herein show that volcanic rocks in the Meacham Hill area and extending southwest to the Burdell Mountain fault are also part of the Tolay Volcanics. In the Sonoma volcanic field, strongly bimodal volcanic sequences are intercalated with sediments. In the Mayacmas Mountains a belt of eruptive centers youngs to the north. The youngest of these volcanic centers at Sugarloaf Ridge, which lithologically, chemically, and temporally matches the Napa Valley eruptive center, was apparently displaced 30 km to the northwest by movement along the Carneros and West Napa faults. The older parts of the Sonoma Volcanics have been displaced at least 28 km along the Rodgers Creek fault since ca. 7 Ma. The Petaluma Formation also youngs to the north along the Rodgers Creek–Hayward fault and the Bennett Valley fault. The Petaluma basin formed as part of the Contra Costa basin in the Late Miocene and

ASI-Volcanic Risk System (SRV): a pilot project to develop EO data processing modules and products for volcanic activity monitoring, first results.

NASA Astrophysics Data System (ADS)

Silvestri, M.; Musacchio, M.; Buongiorno, M. F.; Dini, L.

2009-04-01

The Project called Sistema Rischio Vulcanico (SRV) is funded by the Italian Space Agency (ASI) in the frame of the National Space Plan 2003-2005 under the Earth Observations section for natural risks management. The SRV Project is coordinated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) which is responsible at national level for the volcanic monitoring. The project philosophy is to implement, by incremental versions, specific modules which allow to process, store and visualize through Web GIS tools geophysical parameters suitable for volcanic risk management. The ASI-SRV is devoted to the development of an integrated system based on Earth Observation (EO) data to respond to specific needs of the Italian Civil Protection Department (DPC) and improve the monitoring of Italian active volcanoes during all the risk phases (Pre Crisis, Crisis and Post Crisis). The ASI-SRV system provides support to risk managers during the different volcanic activity phases and its results are addressed to the Italian Civil Protection Department (DPC). SRV provides the capability to manage the import many different EO data into the system, it maintains a repository where the acquired data have to be stored and generates selected volcanic products. The processing modules for EO Optical sensors data are based on procedures jointly developed by INGV and University of Modena. This procedures allow to estimate a number of parameters such as: surface thermal proprieties, gas, aerosol and ash emissions and to characterize the volcanic products in terms of composition and geometry. For the analysis of the surface thermal characteristics, the available algorithms allow to extract information during the prevention phase and during the Warning and Crisis phase. In the prevention phase the thermal analysis is directed to the identification of temperature variation on volcanic structure which may indicate a change in the volcanic activity state. At the moment the only sensor that

When Did Midcontinent Rift Volcanism End and Where Was Laurentia at that Time?

NASA Astrophysics Data System (ADS)

Fairchild, L. M.; Swanson-Hysell, N.; Ramezani, J.; Sprain, C. J.; Gaastra, K. M.; Bowring, S. A.

2015-12-01

Data from the North American Midcontinent Rift provide a robust record of Laurentia's (cratonic North America's) paleogeographic position from ca. 1110 to 1080 Ma. The resulting apparent polar wander path (APWP) reveals rapid motion of the continent towards the equator throughout the rift's lifetime. Constraints on the age of the youngest volcanics within the rift and on the paleolatitude of Laurentia at that time are important for quantifying the rate of this motion and its apparent deceleration in the late stage of rift development. Furthermore, precise calibration of the APWP enhances the robustness of paleogeographic reconstructions. The three rift successions with ca. 1090 to 1085 Ma late stage volcanics are the Lake Shore Traps of Michigan, the Michipicoten Island Formation of Ontario and the Schroeder-Lutsen basalts of Minnesota. In past studies, paleomagnetic data from the Schroeder-Lutsen basalts have been grouped with results from the North Shore Volcanic Group, which it unconformably overlies. In this study, we separate these data and add newly developed results from 40 additional flows. New data from the Michipicoten Island Formation allow for a well constrained pole that now includes data from more than 25 flows. High quality paleomagnetic data are published for the Lake Shore Traps, and we complement these with a newly developed high precision U-Pb zircon date as an update to current constraints. Taken altogether, these data strengthen our understanding of the rift's demise and the rate of Laurentia's motion as rift volcanism gave way to post-rift sedimentation.

Hunting for the Tristan mantle plume - An upper mantle tomography around the volcanic island of Tristan da Cunha

NASA Astrophysics Data System (ADS)

Schlömer, Antje; Geissler, Wolfram H.; Jokat, Wilfried; Jegen, Marion

2017-03-01

The active volcanic island Tristan da Cunha, located at the southwestern and youngest end of the Walvis Ridge - Tristan/Gough hotspot track, is believed to be the surface expression of a huge thermal mantle anomaly. While several criteria for the diagnosis of a classical hotspot track are met, the Tristan region also shows some peculiarities. Consequently, it is vigorously debated if the active volcanism in this region is the expression of a deep mantle plume, or if it is caused by shallow plate tectonics and the interaction with the nearby Mid-Atlantic Ridge. Because of a lack of geophysical data in the study area, no model or assumption has been completely confirmed. We present the first amphibian P-wave finite-frequency travel time tomography of the Tristan da Cunha region, based on cross-correlated travel time residuals of teleseismic earthquakes recorded by 24 ocean-bottom seismometers. The data can be used to image a low velocity structure southwest of the island. The feature is cylindrical with a radius of ∼100 km down to a depth of 250 km. We relate this structure to the origin of Tristan da Cunha and name it the Tristan conduit. Below 250 km the low velocity structure ramifies into narrow veins, each with a radius of ∼50 km. Furthermore, we imaged a linkage between young seamounts southeast of Tristan da Cunha and the Tristan conduit.

Galileo SSI Observations of Volcanic Activity at Tvashtar Catena, Io

NASA Technical Reports Server (NTRS)

Milazzo, M. P.; Keszthely, L. P.; Radebaugh, J.; Davies, A. G.; Turtle, E. P.; Geissler, P.; Klaasen, K. P.; McEwen, A. S.

2005-01-01

Introduction: We report on the analysis of the Galileo SSI's observations of the volcanic activity at Tvashtar Catena, Io as discussed by Milazzo et al. Galileo's Solid State Imager (SSI) observed Tvashtar Catena (63 deg N, 120 deg W) four times between November 1999 and October 2001, providing a unique look at the distinctive high latitude volcanism on Io. The November 1999 observation spatially resolved, for the first time, an active extraterrestrial fissure eruption. The brightness temperature of the lavas at the November 1999 fissure eruption was 1300 K. The second observation (orbit I27, February 2000) showed a large (approx. 500 sq km) region with many, small spots of hot, active lava. The third observation was taken in conjunction with a Cassini observation in December 2000 and showed a Pele-like plume deposition ring, while the Cassini images revealed a 400 km high Pele-type plume above the Catena. The final Galileo SSI observation of Tvashtar was acquired in October 2001, and all obvious (to SSI) activity had ceased, although data from Galileo's Near Infrared Mapping Spectrometer (NIMS) indicated that there was still significant thermal emission from the Tvashtar region. We have concentrated on analyzing the style of eruption during orbit I27 (February 2000). Comparison with a lava flow cooling model indicates that the behavior of the Tvashtar eruption during I27 does not match that of "simple" advancing lava flows. Instead, it may be an active lava lake or a complex set of lava flows with episodic, overlapping (in time and space) eruptions.

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

NASA Astrophysics Data System (ADS)

Escobar-Wolf, R. P.; Chigna, G.; Morales, H.; Waite, G. P.; Oommen, T.; Lechner, H. N.

2015-12-01

Pacaya volcano is a frequently active and potentially dangerous volcano situated in the Guatemalan volcanic arc. It is also a National Park and a major touristic attraction, constituting an important economic resource for local municipality and the nearby communities. Recent eruptions have caused fatalities and extensive damage to nearby communities, highlighting the need for risk management and loss reduction from the volcanic activity. Volcanic monitoring at Pacaya is done by the Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH), instrumentally through one short period seismic station, and visually by the Parque Nacional Volcan de Pacaya y Laguna de Calderas (PNVPLC) personnel. We carry out a project to increase the local technical capacities for monitoring volcanic activity at Pacaya. Funding for the project comes from the Society of Exploration Geophysicists through the Geoscientists Without Borders program. Three seismic and continuous GPS stations will be installed at locations within 5 km from the main vent at Pacaya, and one webcam will aid in the visual monitoring tasks. Local educational and outreach components of the project include technical workshops on data monitoring use, and short thesis projects with the San Carlos University in Guatemala. A small permanent exhibit at the PNVPLC museum or visitor center, focusing on the volcano's history, hazards and resources, will also be established as part of the project. The strategy to involve a diverse group of local collaborators in Guatemala aims to increase the chances for long term sustainability of the project, and relies not only on transferring technology but also the "know-how" to make that technology useful. Although not a primary research project, it builds on a relationship of years of joint research projects at Pacaya between the participants, and could be a model of how to increase the broader impacts of such long term collaboration partnerships.

Exploring for Volcanic and Hydrothermal Activity Above Off-axis Melt Lenses near the East Pacific Rise

NASA Astrophysics Data System (ADS)

White, S. M.; Lee, A. J.; Rubin, K. H.

2015-12-01

Two Alvin dives (AL 4771 and 4774) transected the seafloor directly above the two largest Off-Axis Melt Lenses (O-AML) east of the East Pacific Rise (EPR) axis at 9 39'N and 9 54'N. In 2008, a 3D high-resolution seismic reflection survey (MGL-0812) discovered O-AMLs 3-7 km from the EPR at 2-3 km below the seafloor. Several other O-AML in the crust have been subsequently detected in several locations up to 20 km from the spreading axis at fast and intermediate spreading ridges; understanding their impacts is increasingly important. During the dives, no currently active hydrothermal venting or fresh lava was seen, suggesting that these features do not constantly power off-axis geological activity. However, the seafloor appears much younger at small volcanic seamounts in the 9 39'N than at the 9 54'N site. At 9 39'N, we used Alvin to explore the off-axis volcanic mound complex, reaching the summit of the three largest mounds. Although no evidence for on-going hydrothermal or volcanic activity was detected, the seafloor wore a thin sediment layer of ~10cm and thin Mn-coatings on 9 rock samples, suggesting volcanism more recently than would be expected based on the spreading-rate age of the crust. At 9 54'N, the Alvin trackline started south of a prominent abyssal hill, which has an unusual D-shape over 1 km wide in the center, crossed the abyssal hill, visited two local hummocks on top, and then attempted to find volcanic activity on the near slope of EPR axis by going as far west was possible during the dive. Heavy sediment everywhere on the abyssal hill, to the depth of push cores (~30 cm) and probably much deeper in many areas and 4 rock samples from the abyssal hill were quite weathered with little glass intact, suggest that this site is unaffected by the underlying O-AML. Upslope toward the EPR west of the abyssal hill, 4 rocks collected appear somewhat younger, and sediment became thinner. In addition, 3 CTD tow-yos over each O-AML found no evidence of active

Exploring for Volcanic and Hydrothermal Activity Above Off-axis Melt Lenses near the East Pacific Rise

NASA Astrophysics Data System (ADS)

West, A. J.; Torres, M. A.; Nealson, K. H.

2014-12-01

Two Alvin dives (AL 4771 and 4774) transected the seafloor directly above the two largest Off-Axis Melt Lenses (O-AML) east of the East Pacific Rise (EPR) axis at 9 39'N and 9 54'N. In 2008, a 3D high-resolution seismic reflection survey (MGL-0812) discovered O-AMLs 3-7 km from the EPR at 2-3 km below the seafloor. Several other O-AML in the crust have been subsequently detected in several locations up to 20 km from the spreading axis at fast and intermediate spreading ridges; understanding their impacts is increasingly important. During the dives, no currently active hydrothermal venting or fresh lava was seen, suggesting that these features do not constantly power off-axis geological activity. However, the seafloor appears much younger at small volcanic seamounts in the 9 39'N than at the 9 54'N site. At 9 39'N, we used Alvin to explore the off-axis volcanic mound complex, reaching the summit of the three largest mounds. Although no evidence for on-going hydrothermal or volcanic activity was detected, the seafloor wore a thin sediment layer of ~10cm and thin Mn-coatings on 9 rock samples, suggesting volcanism more recently than would be expected based on the spreading-rate age of the crust. At 9 54'N, the Alvin trackline started south of a prominent abyssal hill, which has an unusual D-shape over 1 km wide in the center, crossed the abyssal hill, visited two local hummocks on top, and then attempted to find volcanic activity on the near slope of EPR axis by going as far west was possible during the dive. Heavy sediment everywhere on the abyssal hill, to the depth of push cores (~30 cm) and probably much deeper in many areas and 4 rock samples from the abyssal hill were quite weathered with little glass intact, suggest that this site is unaffected by the underlying O-AML. Upslope toward the EPR west of the abyssal hill, 4 rocks collected appear somewhat younger, and sediment became thinner. In addition, 3 CTD tow-yos over each O-AML found no evidence of active

Late Ediacaran volcano-sedimentary successions of southern Sinai (Egypt): tracing the evolution from late- to post-collisional volcanism and its relation to A-type rocks

NASA Astrophysics Data System (ADS)

Azer, Mokhles; Asimow, Paul; Obeid, Mohamed; Price, Jason; Wang, Max

2017-04-01

The Late Ediacaran post-collisional volcano-sedimentary successions exposed in southern Sinai (Egypt) represent the last stage of magmatic activity associated with assembly of the northernmost segment of the Neoproterozoic Arabian-Nubian Shield. To clarify the age and tempo of post-collisional activity, three volcanic successions from southern Sinai were selected for the present study: the Sahiya, Iqna Shar'a and Meknas volcanics. They comprise a series of intermediate to silicic volcanic flows and their pyroclastic rocks. New zircon U-Pb dating by SIMS of the lava flows from the three successions yielded ages ranging between ca. 619 to 600 Ma. Combined with field evidence and the geochemical data, the obtained SIMS zircon ages enable us to recognize two phases of volcanic activity in southern Sinai at ca. 619-615 Ma and 606-600 Ma. Both age groups were found within the more northerly volcanic successions at Iqna Shar'a and Meknas and in both these sequences the younger phase uncomformably overlies the older phase. Only the older ages, ca. 615-619 Ma, were found in the Sahiya volcanics, exposed at the southern tip of Sinai. The ages of the youngest calc-alkaline volcanics in the study areas are similar to or slightly younger than the earliest phases of alkaline volcanism in southern Sinai, indicating coeval extrusion of calc-alkalic and alkalic A-type rocks. This observation corroborates similar observations documenting cogenetic calc-alkalic and alkalic plutons in the surrounding areas in southern Sinai. Geochemically, the volcanic rocks of the three successions display large silica variations and are mostly medium- to high-K calc-alkaline rocks. The first phase, from ca. 619-615 Ma, observed in all three volcanic suites, comprises basaltic andesite, andesite and dacite, whereas the second phase, from ca. 606-600 Ma and observed only in the northern volcanic suites (Iqna Shar'a and Meknas), comprises dacite, rhyodacite and rhyolite. In the Sahiya succession basal

Earth's youngest exposed granite and its tectonic implications: the 10-0.8 Ma Kurobegawa Granite.

PubMed

Ito, Hisatoshi; Yamada, Ryuji; Tamura, Akihiro; Arai, Shoji; Horie, Kenji; Hokada, Tomokazu

2013-01-01

Although the quest for Earth's oldest rock is of great importance, identifying the youngest exposed pluton on Earth is also of interest. A pluton is a body of intrusive igneous rock that crystallized from slowly cooling magma at depths of several kilometers beneath the surface of the Earth. Therefore, the youngest exposed pluton represents the most recent tectonic uplift and highest exhumation. The youngest exposed pluton reported to date is the Takidani Granodiorite (~ 1.4 Ma) in the Hida Mountain Range of central Japan. Using LA-ICP-MS and SHRIMP U-Pb zircon dating methods, this study demonstrates that the Kurobegawa Granite, also situated in the Hida Mountain Range, is as young as ~ 0.8 Ma. In addition, data indicate multiple intrusion episodes in this pluton since 10 Ma with a ~ 2-million-year period of quiescence; hence, a future intrusion event is likely within 1 million years.

Study of the structure changes caused by volcanic activity in Mexico applying the lineament analysis to the Aster (Terra) satellite data.

NASA Astrophysics Data System (ADS)

Arellano-Baeza, A. A.; Garcia, R. V.; Trejo-Soto, M.; Molina-Sauceda, E.

Mexico is one of the most volcanically active regions in North America Volcanic activity in central Mexico is associated with the subduction of the Cocos and Rivera plates beneath the North American plate Periods of enhanced microseismic activity associated with the volcanic activity of the Colima and Popocapetl volcanoes are compared to some periods of low microseismic activity We detected changes in the number and orientation of lineaments associated with the microseismic activity due to lineament analysis of a temporal sequence of high resolution satellite images of both volcanoes 15 m resolution multispectral images provided by the ASTER VNIR instrument were used The Lineament Extraction and Stripes Statistic Analysis LESSA software package was employed for the lineament extraction

Radio Telescopes Reveal Youngest Stellar Corpse

NASA Astrophysics Data System (ADS)

2004-06-01

Astronomers using a global combination of radio telescopes to study a stellar explosion some 30 million light-years from Earth have likely discovered either the youngest black hole or the youngest neutron star known in the Universe. Their discovery also marks the first time that a black hole or neutron star has been found associated with a supernova that has been seen to explode since the invention of the telescope nearly 400 years ago. M51 An artist's impression of Supernova 1986J. The newly discovered nebula around the black hole or neutron star in the center is shown in blue, and is in the center of the expanding, fragmented shell of material thrown off in the supernova explosion, which is shown in red. CREDIT: Norbert Bartel and Michael F. Bietenholz, York University; Artist: G. Arguner (Click on image for larger version) Image Files Artist's Conception (above image, 836K) Galaxy and Supernova (47K) A VLA image (left) of the galaxy NGC 891, showing the bright supernova explosion below the galaxy's center. At right, a closer view of the supernova, made with a global array of radio telescopes. CREDIT: Miguel A. Perez-Torres, Antxon Alberdi and Lucas Lara, Instituto de Astrofisica de Andalucia - CSIC, Spain, Jon Marcaide and Jose C. Guirado, Universidad de Valencia, Spain Franco Mantovani, IRA-CNR, Italy, Eduardo Ros, MPIfR, Germany, and Kurt W. Weiler, Naval Research Laboratory, USA Multi-Frequency Closeup View (201K) Blue and white area shows the nebula surrounding the black hole or neutron star lurking in the center of the supernova. This nebula is apparent at a higher radio frequency (15 GHz). The red and also the contours show the distorted, expanding shell of material thrown off in the supernova explosion. This shell is seen at a lower radio frequency (5 GHz). CREDIT: Michael F. Bietenholz and Norbert Bartel, York University, Michael Rupen, NRAO, NRAO/AUI/NSF A supernova is the explosion of a massive star after it exhausts its supply of nuclear fuel and

The Western Arabian intracontinental volcanic fields as a potential UNESCO World Heritage site

NASA Astrophysics Data System (ADS)

Németh, Károly; Moufti, Mohammed R.

2017-04-01

considerred to be associated with dispersed intracontinental volcanic fields. In addition the nominated volcanic region also hosts the largest and youngest historic eruption (Al Madinah Eruption) in Western Saudi Arabia took place at 1256-AD, lasted 52 days and produced at least 0.29-km3 of pahoehoe-to-aa transitional lava fields that were emitted through a 2.3 km-long fissure and associated spatter-to-scoria cone complexes. The Western Arabian intracontinental volcanic fields provide the best exposed and most diverse type of intracontinental volcanic fields on Earth that also occupies the largest surface area. In addition, this chain of volcanic fields are also host significant archaeological and human occupation sites help to understand early human evolution as well as hosting several historic locations with high cultural heritage values. These generally intact and well-exposed volcanic zones hosting globally unique geoheritage sites can form the basis of complex geoeducational programs through the establishment of various volcanic geoparks in the region that can link together a UNESCO World Heritage Site on the basis of their global universal volcanic geoheritage values.

Valuing lives and allocating resources: a defense of the modified youngest first principle of scarce resource distribution.

PubMed

Tallman, Ruth

2014-06-01

In this paper, I argue that the 'modified youngest first' principle provides a morally appropriate criterion for making decisions regarding the distribution of scarce medical resources, and that it is morally preferable to the simple 'youngest first' principle. Based on the complete lives system's goal of maximizing complete lives rather than individual life episodes, I argue that essential to the value we see in complete lives is the first person value attributed by the experiencer of that life. For a life to be 'complete' or 'incomplete,' the subject of that life must be able to understand the concept of a complete life, to have started goals and projects, and to know what it would be for that life to be complete. As the very young are not able to do this, it can reasonably be said that their characteristically human lives have not yet begun, giving those accepting a complete lives approach good reason to accept the modified youngest first principle over a simple 'youngest first' approach. © 2012 John Wiley & Sons Ltd.

Crustal deformation and volcanism at active plate boundaries

NASA Astrophysics Data System (ADS)

Geirsson, Halldor

Most of Earth's volcanoes are located near active tectonic plate boundaries, where the tectonic plates move relative to each other resulting in deformation. Likewise, subsurface magma movement and pressure changes in magmatic systems can cause measurable deformation of the Earth's surface. The study of the shape of Earth and therefore studies of surface deformation is called geodesy. Modern geodetic techniques allow precise measurements (˜1 mm accuracy) of deformation of tectonic and magmatic systems. Because of the spatial correlation between tectonic boundaries and volcanism, the tectonic and volcanic deformation signals can become intertwined. Thus it is often important to study both tectonic and volcanic deformation processes simultaneously, when one is trying to study one of the systems individually. In this thesis, I present research on crustal deformation and magmatic processes at active plate boundaries. The study areas cover divergent and transform plate boundaries in south Iceland and convergent and transform plate boundaries in Central America, specifically Nicaragua and El Salvador. The study is composed of four main chapters: two of the chapters focus on the magma plumbing system of Hekla volcano, Iceland and the plate boundary in south Iceland; one chapter focuses on shallow controls of explosive volcanism at Telica volcano, Nicaragua; and the fourth chapter focuses on co- and post-seismic deformation from a Mw = 7.3 earthquake which occurred offshore El Salvador in 2012. Hekla volcano is located at the intersection of a transform zone and a rift zone in Iceland and thus is affected by a combination of shear and extensional strains, in addition to co-seismic and co-rifting deformation. The inter-eruptive deformation signal from Hekla is subtle, as observed by a decade (2000-2010) of GPS data in south Iceland. A simultaneous inversion of this data for parameters describing the geometry and source characteristics of the magma chamber at Hekla, and

Assessing the Altitude and Dispersion of Volcanic Plumes Using MISR Multi-angle Imaging from Space: Sixteen Years of Volcanic Activity in the Kamchatka Peninsula, Russia

NASA Technical Reports Server (NTRS)

Flower, Verity J. B.; Kahn, Ralph A.

2017-01-01

Volcanic eruptions represent a significant source of atmospheric aerosols and can display local, regional and global effects, impacting earth systems and human populations. In order to assess the relative impacts of these events, accurate plume injection altitude measurements are needed. In this work, volcanic plumes generated from seven Kamchatka Peninsula volcanoes (Shiveluch, Kliuchevskoi, Bezymianny, Tolbachik, Kizimen, Karymsky and Zhupanovsky), were identified using over 16 years of Multi-angle Imaging SpectroRadimeter (MISR) measurements. Eighty-eight volcanic plumes were observed by MISR, capturing 3-25% of reported events at individual volcanoes. Retrievals were most successful where high intensity events persisted over a period of weeks to months. Compared with existing ground and airborne observations, and alternative satellite-based reports compiled by the Global Volcanism Program (GVP), MISR plume height retrievals showed general consistency; the comparison reports appear to be skewed towards the region of highest concentration observed in MISR-constrained vertical plume extent. The report observations display less discrepancy with MISR toward the end of the analysis period, with improvements in the suborbital data likely the result of the deployment of new instrumentation. Conversely, the general consistency of MISR plume heights with conventionally reported observations supports the use of MISR in the ongoing assessment of volcanic activity globally, especially where other types of volcanic plume observations are unavailable. Differences between the northern (Shiveluch, Kliuchevskoi, Bezymianny and Tolbachik) and southern (Kizimen, Karymsky and Zhupanovsky) volcanoes broadly correspond to the Central Kamchatka Depression (CKD) and Eastern Volcanic Front (EVF), respectively, geological sub-regions of Kamchatka distinguished by varying magma composition. For example, by comparison with reanalysis-model simulations of local meteorological conditions

Hazards in volcanic arcs

NASA Astrophysics Data System (ADS)

Sparks, S. R.

2008-12-01

Volcanic eruptions in arcs are complex natural phenomena, involving the movement of magma to the Earth's surface and interactions with the surrounding crust during ascent and with the surface environment during eruption, resulting in secondary hazards. Magma changes its properties profoundly during ascent and eruption and many of the underlying processes of heat and mass transfer and physical property changes that govern volcanic flows and magmatic interactions with the environment are highly non-linear. Major direct hazards include tephra fall, pyroclastic flows from explosions and dome collapse, volcanic blasts, lahars, debris avalanches and tsunamis. There are also health hazards related to emissions of gases and very fine volcanic ash. These hazards and progress in their assessment are illustrated mainly from the ongoing eruption of the Soufriere Hills volcano. Montserrat. There are both epistemic and aleatory uncertainties in the assessment of volcanic hazards, which can be large, making precise prediction a formidable objective. Indeed in certain respects volcanic systems and hazardous phenomena may be intrinsically unpredictable. As with other natural phenomena, predictions and hazards inevitably have to be expressed in probabilistic terms that take account of these uncertainties. Despite these limitations significant progress is being made in the ability to anticipate volcanic activity in volcanic arcs and, in favourable circumstances, make robust hazards assessments and predictions. Improvements in monitoring ground deformation, gas emissions and seismicity are being combined with more advanced models of volcanic flows and their interactions with the environment. In addition more structured and systematic methods for assessing hazards and risk are emerging that allow impartial advice to be given to authorities during volcanic crises. There remain significant issues of how scientific advice and associated uncertainties are communicated to provide effective

Volcanic processes in the solar system

USGS Publications Warehouse

Carr, M.H.

1987-01-01

Eruptions of ammonia, water, and sulfur. These have become some of the concerns of planetary volcanologists as they try to understand volcanic processes on other planetary bodies. As exploration of the Solar System has continues, we have been confronted with more and more exotic forms of volcanism and have come to realize that the types of volcanic activity observed on Earth represent only a fraction of the array of volcanic phenomena that are possible. Some volcanic features of other planets have close terrestrial counterparts and appear to have been formed by similar mechanisms and from similar magmas to those on the Earth. but other features are totally different and appear to have been formed from materials that are not normally associated with volcanism on Earth.

Gravimetric control of active volcanic processes

NASA Astrophysics Data System (ADS)

Saltogianni, Vasso; Stiros, Stathis

2017-04-01

Volcanic activity includes phases of magma chamber inflation and deflation, produced by movement of magma and/or hydrothermal processes. Such effects usually leave their imprint as deformation of the ground surfaces which can be recorded by GNSS and other methods, on one hand, and on the other hand they can be modeled as elastic deformation processes, with deformation produced by volcanic masses of finite dimensions such as spheres, ellipsoids and parallelograms. Such volumes are modeled on the basis of inversion (non-linear, numerical solution) of systems of equations relating the unknown dimensions and location of magma sources with observations, currently mostly GNSS and INSAR data. Inversion techniques depend on the misfit between model predictions and observations, but because systems of equations are highly non-linear, and because adopted models for the geometry of magma sources is simple, non-unique solutions can be derived, constrained by local extrema. Assessment of derived magma models can be provided by independent observations and models, such as micro-seismicity distribution and changes in geophysical parameters. In the simplest case magmatic intrusions can be modeled as spheres with diameters of at least a few tens of meters at a depth of a few kilometers; hence they are expected to have a gravimetric signature in permanent recording stations on the ground surface, while larger intrusions may also have an imprint in sensors in orbit around the earth or along precisely defined air paths. Identification of such gravimetric signals and separation of the "true" signal from the measurement and ambient noise requires fine forward modeling of the wider areas based on realistic simulation of the ambient gravimetric field, and then modeling of its possible distortion because of magmatic anomalies. Such results are useful to remove ambiguities in inverse modeling of ground deformation, and also to detect magmatic anomalies offshore.

Short-term volcanic hazard assessment through Bayesian inference: retrospective application to the Pinatubo 1991 volcanic crisis

NASA Astrophysics Data System (ADS)

Sobradelo, Rosa; Martí, Joan

2015-01-01

One of the most challenging aspects of managing a volcanic crisis is the interpretation of the monitoring data, so as to anticipate to the evolution of the unrest and implement timely mitigation actions. An unrest episode may include different stages or time intervals of increasing activity that may or may not precede a volcanic eruption, depending on the causes of the unrest (magmatic, geothermal or tectonic). Therefore, one of the main goals in monitoring volcanic unrest is to forecast whether or not such increase of activity will end up with an eruption, and if this is the case, how, when, and where this eruption will take place. As an alternative method to expert elicitation for assessing and merging monitoring data and relevant past information, we present a probabilistic method to transform precursory activity into the probability of experiencing a significant variation by the next time interval (i.e. the next step in the unrest), given its preceding evolution, and by further estimating the probability of the occurrence of a particular eruptive scenario combining monitoring and past data. With the 1991 Pinatubo volcanic crisis as a reference, we have developed such a method to assess short-term volcanic hazard using Bayesian inference.

Characterization of the Etna volcanic emissions through an active biomonitoring technique (moss-bags): part 1--major and trace element composition.

PubMed

Calabrese, S; D'Alessandro, W; Bellomo, S; Brusca, L; Martin, R S; Saiano, F; Parello, F

2015-01-01

Active biomonitoring using moss-bags was applied to an active volcanic environment for the first time. Bioaccumulation originating from atmospheric deposition was evaluated by exposing mixtures of washed and air-dried mosses (Sphagnum species) at 24 sites on Mt. Etna volcano (Italy). Concentrations of major and a large suite of trace elements were analysed by inductively coupled mass and optical spectrometry (ICP-MS and ICP-OES) after total acid digestion. Of the 49 elements analysed those which closely reflect summit volcanic emissions were S, Tl, Bi, Se, Cd, As, Cu, B, Na, Fe, Al. Enrichment factors and cluster analysis allowed clear distinction between volcanogenic, geogenic and anthropogenic inputs that affect the local atmospheric deposition. This study demonstrates that active biomonitoring with moss-bags is a suitable and robust technique for implementing inexpensive monitoring in scarcely accessible and harsh volcanic environments, giving time-averaged quantitative results of the local exposure to volcanic emissions. This task is especially important in the study area because the summit area of Mt. Etna is visited by nearly one hundred thousand tourists each year who are exposed to potentially harmful volcanic emissions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanical interaction between volcanic systems in Libya

NASA Astrophysics Data System (ADS)

Elshaafi, Abdelsalam; Gudmundsson, Agust

2018-01-01

The spatial distributions of monogenetic volcanoes, primarily volcanic craters, within the four principal volcanic provinces of Libya are examined and presented on a volcano-density map. Six main volcanic clusters have been identified, referred to as volcanic systems. Remarkably, the Al Haruj (AHVP) and Nuqay (NVP) volcanic provinces have double-peak volcano-density distributions, while the Gharyan (GVP) and As Sawda (SVP) volcanic provinces have single-peak volcano-density distributions. We interpret each volcano-density peak as corresponding to a separate volcanic system, so that there is a total of six systems in these four provinces. There was an overlap in volcanic activity in these provinces with at least three simultaneously active. We propose that each of the 6 volcanic systems was/is supplied with magma from a large sill-like reservoir - similar in lateral dimensions to the systems/clusters themselves. Numerical results show zones of high tensile and shear stresses between the reservoirs that coincide roughly with the main swarms of extension (dykes and volcanic fissures) and shear (faults) fractures in the areas. The most recent volcanic eruptions in Libya fall within the modelled high-stress concentration zones, primarily eruptions in the volcano Waw an Namus and the Holocene Al Mashaqaq lava flow. There are no known eruptions in Libya in historical time, but some or all the volcanic systems may have had one or more arrested historical dyke injections. In particular, part of the recurrent seismic events in the Hun Graben in the northwest Libya may be related to dyke propagation and arrest. If some of the inferred magma reservoirs are still fluid, as is likely, they pose earthquake and volcanic hazards to parts of Libya, particularly to the city of Gharyan and Zallah town, as well as to many oil-field operations.

A geochronological study of mafic and acidic lavas from Veneto Volcanic province (North-East Italy)

NASA Astrophysics Data System (ADS)

Brombin, Valentina; Webb, Laura; Bonadiman, Costanza; Marzoli, Andrea; Coltorti, Massimo

2017-04-01

The Veneto Volcanic Province (VVP), in the North-East of Italy represents one of the most important magmatic province of the Adria Plate. VVP magmatism occurred in a period ranging from late Paleocene to late Oligocene (De Vecchi et al., 1976). Five main volcanic districts can be defined from north-west to south-east: Val d'Adige, Marosticano, Lessini Hills, Berici Hills and Euganean Hills. Most of the volcanic products are relatively undifferentiated lavas, ranging in compostion from mela-nephelinites to quartz-normative tholeiites (Beccaluva et al., 2007). By contrast in the Euganean Hills volcanic and subvolcanic rocks range from subordinate basalts to prevalently acidic types, mostly quartz-trachytes and rhyolites (Milani et al., 1999). Despite of the deep petrological knowledge about this province, the radioisotopic ages of the related volcanic activities for each district are still poorly defined or even totally missing. 40Ar/39Ar ages on 9 samples have been obtained to determine the age range for the VVP. 40Ar/39Ar whole rock step heating analyses yielded ages ranging from 40.7 ± 0.2 Ma to 23.3 ± 1.5 Ma for basanites of Val d'Adige and Marosticano area, respectively. For the Lessinean district, 40Ar/39Ar whole rock analyses for two basanites, one trachybasalt and one alkali basalt close to 40 Ma, while a tholeiite from the same area yielded the youngest age for this district (i.e. 32.9 ± 1.8 Ma). This young age is comparable to 40Ar/39Ar ages obtained for the Euganean Hills intermediate-acidic rocks (Jourdan, pers. comm., 2016), suggesting a time-related shift from more alkaline to Si-saturated magmatism in the whole province. References Barbieri G., Medizza F. (1969). Contributo alla conoscenza geologica della regione di Bolca (Monti Lessini). Memorie dell'Istituto di Geologia e Mineralogia dell'Università di Padova, 27, 1-36. Beccaluva L., Bianchini G., Bonadiman C., Coltorti M., Milani L., Salvini L., Siena F., Tassinari R. (2007). Intraplate

Quantitative Studies in Planetary Volcanism

NASA Technical Reports Server (NTRS)

Baloga, Stephen M.

2004-01-01

Proxemy Research has a research grant to perform scientific investigations of volcanism and volcanic-related process on other planets. Part of this research involves mathematical modeling of specific volcanic transport processes and the use of terrestrial analogs. This report contains a summary of activities conducted over the time period indicated. In addition, a synopsis of science research conducted during the period is given. A complete listing of publications and scientific abstracts that were presented at scientific conferences is contained in the report.

[Book review] The youngest science: notes of a medicine-watcher, by Lewis Thomas

USGS Publications Warehouse

Johnson, D.H.

1984-01-01

Review of: The youngest science: notes of a medicine-watcher. Alfred P. Sloan Foundation Series. Lewis Thomas. Penguin Books, 1995. Pennsylvania State University. 270 pp. ISBN: 0140243275, 9780140243277.

Relationship between the latest activity of mare volcanism and topographic features of the Moon

NASA Astrophysics Data System (ADS)

Kato, Shinsuke; Morota, Tomokatsu; Yamaguchi, Yasushi; Watanabe, Sei-ichiro; Otake, Hisashi; Ohtake, Makiko

2016-04-01

Lunar mare basalts provide insights into compositions and thermal history of lunar mantle. According to crater counting analysis with remote sensing data, the model ages of mare basalt units indicate a second peak of magma activity at the end of mare volcanism (~2 Ga), and the latest eruptions were limited in the Procellarum KREEP Terrane (PKT), which has high abundances of heat-producing elements. In order to understand the mechanism for causing the second peak and its magma source, we examined the correlation between the titanium contents and eruption ages of mare basalt units using compositional and chronological data updated by SELENE/Kaguya. Although no systematic relationship is observed globally, a rapid increase in mean titanium (Ti) content occurred at 2.3 Ga in the PKT, suggesting that the magma source of mare basalts changed at that time. The high-Ti basaltic eruption, which occurred at the late stage of mare volcanism, can be correlated with the second peak of volcanic activity at ~2 Ga. The latest volcanic activity can be explained by a high-Ti hot plume originated from the core-mantle boundary. If the hot plume was occurred, the topographic features formed by the hot plume may be remained. We calculated the difference between topography and selenoid and found the circular feature like a plateau in the center of the PKT, which scale is ~1000 km horizontal and ~500 m vertical. We investigated the timing of ridge formation in the PKT by using stratigraphic relationship between mare basalts and ridges. The ridges were formed before and after the high-Ti basaltic eruptions and seem to be along with the plateau. These results suggest that the plateau formation is connected with the high-Ti basaltic eruptions.

Electrical resistivity structure beneath the Hangai Dome, Mongolia: intraplate volcanism and deformation imaged with magnetotelluric data

NASA Astrophysics Data System (ADS)

Comeau, M. J.; Becken, M.; Kaeufl, J.; Kuvshinov, A. V.; Kamm, J.; Grayver, A.; Demberel, S.; Usnikh, S. U.; Batmagnai, E.; Tserendug, S.

2017-12-01

The Hangai Dome in central Mongolia is characterized by intraplate volcanism on a high-elevation intra-continental plateau. Volcanism dates from the Oligocene to the Holocene and is thought to be coincident with the onset of the uplift of the Hangai Dome, indicating that the processes may be linked. However, the processes and driving mechanisms responsible for creating this region remain largely unexplained, due in part to a lack of high-resolution geophysical data over the area. An extensive magnetotelluric (MT) data set was collected over the Hangai Dome in 2016 and 2017, with broadband data (0.002 - 5,000 s) collected at a total of 294 sites. This data set consists of a large array ( 50 km site spacing) and several long ( 600 km) and dense ( 5 km site spacing) profiles that cross the uplifted Hangai Dome. Additionally, they cross the bounding faults of the Hangai block, the Bulnay fault in the north and the Bogd fault of the Gobi-Altai in the south, which have had several M>8 earthquakes in the past century. These MT data have been used to generate electrical resistivity models of the crust and upper mantle in this region. Anomalous, low resistivity ( 30 ohm-m) zones in the lower crust ( 25 - 50 km depth) are spatially associated with the surface expressions of volcanism and modern-day hydrothermal activity. These zones indicate the presence of local accumulations of fluids below the brittle-ductile transition zone. Interestingly, this feature terminates sharply at the South Hangai Fault Zone. Furthermore, lower resistivity pathways in the upper crust (0 - 25 km depth) connect the deeper features to the surface. This is prominently observed below the Hangai's youngest volcanic zones of Tariat/Khorgo and Chuluut, as well as the hot spring area of Tsenkher, near Tsetserleg. Additionally, an electrical signature can be associated with known fault zones and mineralized zones (such as the Bayankhongor mineral belt). An anomalous low-resistivity zone in the upper

Toward a pro-active scientific advice on global volcanic activity within the multi-hazard framework of the EU Aristotle project

NASA Astrophysics Data System (ADS)

Barsotti, Sara; Duncan, Melanie; Loughlin, Susan; Gísladóttir, Bryndis; Roberts, Matthew; Karlsdóttir, Sigrún; Scollo, Simona; Salerno, Giuseppe; Corsaro, Rosa Anna; Charalampakis, Marinos; Papadopoulos, Gerassimos

2017-04-01

The demand for timely analysis and advice on global volcanic activity from scientists is growing. At the same time, decision-makers require more than an understanding of hazards; they need to know what impacts to expect from ongoing and future events. ARISTOTLE (All Risk Integrated System TOwards Trans-boundary hoListic Early-warning) is a two-year EC funded pilot project designed to do just that. The Emergency Response Coordination Centre (ERCC) works to support and coordinate response to disasters both inside and outside Europe using resources from the countries participating in the European Union Civil Protection Mechanism. Led by INGV and ZAMG, the ARISTOTLE consortium comprises 15 institutions across Europe and aims to deliver multi-hazard advice on natural events, including their potential interactions and impact, both inside and outside of Europe to the ERCC. Where possible, the ERCC would like a pro-active provision of scientific advice by the scientific group. Iceland Met Office leads the volcanic hazards work, with BGS, INGV and NOA comprising the volcano observatory team. At this stage, the volcanology component of the project comprises mainly volcanic ash and gas dispersal and potential impact on population and ground-based critical infrastructures. We approach it by relying upon available and official volcano monitoring institutions' reporting of activity, existing assessments and global databases of past events, modelling tools, remote-sensing observational systems and official VAAC advisories. We also make use of global assessments of volcanic hazards, country profiles, exposure and proxy indicators of threat to livelihoods, infrastructure and economic assets (e.g. Global Volcano Model outputs). Volcanic ash fall remains the only hazard modelled at the global scale. Volcanic risk assessments remain in their infancy, owing to challenges related to the multitude of hazards, data availability and model representation. We therefore face a number of

New determinations of 40Ar/39Ar isotopic ages and flow volumes for Cenozoic volcanism in the Terror Rift, Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

Rilling, S.; Mukasa, S.; Wilson, T.; Lawver, L.; Hall, C.

2009-12-01

This study provides new determinations of 40Ar/39Ar isotopic ages and flow volumes for submarine and subaerial Neogene volcanism developed within the Terror Rift, Ross Sea, Antarctica, the youngest segment of the West Antarctic Rift System. The study is based on the first dredged samples from seven seamounts north of Ross Island, as well as new data from Franklin and Beaufort Islands. The sampled foidite and basanitic lavas range in age from Quaternary (90 ± 66 ka) on a small seamount ˜10 km north of Franklin Island to 6.80 ± 0.05 Ma on Beaufort Island. These ages are consistent with ages of volcanism in both the Melbourne and Erebus Volcanic Provinces and significantly expand the documented area of Neogene magmatism in Victoria Land. There is no geographic progression of volcanism through time, but volcanism was voluminous in the Pliocene and particularly widespread during the Pleistocene. Two of the dredges sampled edifices comprised of less than 0.2 km3 of volcanic materials. The largest seamount in the study area has 58.8 km3 of volcanic material and represents growth over a period of several thousand years. Estimated minimum eruption rates range from 2 × 10-4 km3 y-1 to 2 × 10-3 km3 y-1, consistent with rates proposed for other rift systems and nearby Mt. Erebus. Recent estimates of extension magnitude for the Terror Rift correspond to minimal decompression of only 0.10 to 0.22 GPa and therefore limited melt output of a typical peridotite source.

Developing International Guidelines on Volcanic Hazard Assessments for Nuclear Facilities

NASA Astrophysics Data System (ADS)

Connor, Charles

2014-05-01

Worldwide, tremendous progress has been made in recent decades in forecasting volcanic events, such as episodes of volcanic unrest, eruptions, and the potential impacts of eruptions. Generally these forecasts are divided into two categories. Short-term forecasts are prepared in response to unrest at volcanoes, rely on geophysical monitoring and related observations, and have the goal of forecasting events on timescales of hours to weeks to provide time for evacuation of people, shutdown of facilities, and implementation of related safety measures. Long-term forecasts are prepared to better understand the potential impacts of volcanism in the future and to plan for potential volcanic activity. Long-term forecasts are particularly useful to better understand and communicate the potential consequences of volcanic events for populated areas around volcanoes and for siting critical infrastructure, such as nuclear facilities. Recent work by an international team, through the auspices of the International Atomic Energy Agency, has focused on developing guidelines for long-term volcanic hazard assessments. These guidelines have now been implemented for hazard assessment for nuclear facilities in nations including Indonesia, the Philippines, Armenia, Chile, and the United States. One any time scale, all volcanic hazard assessments rely on a geologically reasonable conceptual model of volcanism. Such conceptual models are usually built upon years or decades of geological studies of specific volcanic systems, analogous systems, and development of a process-level understanding of volcanic activity. Conceptual models are used to bound potential rates of volcanic activity, potential magnitudes of eruptions, and to understand temporal and spatial trends in volcanic activity. It is these conceptual models that provide essential justification for assumptions made in statistical model development and the application of numerical models to generate quantitative forecasts. It is a

Laboratory simulations of volcanic ash charging and conditions for volcanic lightning on Venus

NASA Astrophysics Data System (ADS)

Airey, Martin; Warriner-Bacon, Elliot; Aplin, Karen

2017-04-01

Lightning may be important in the emergence of life on Earth and elsewhere, as significant chemical reactions occur in the superheated region around the lightning channel. This, combined with the availability of phosphates in volcanic clouds, suggests that volcanic lightning could have been the catalyst for the formation of biological compounds on the early Earth [1]. In addition to meteorological lightning, volcanic activity also generates electrical discharges within charged ash plumes, which can be a significant contributor to atmospheric electricity on geologically active planets. The physical properties of other planetary atmospheres, such as that of Venus, have an effect on the processes that lead to the generation of volcanic lightning. Volcanism is known to have occurred on Venus in the past, and recent observations made by ESA's Venus Express satellite have provided evidence for currently active volcanism [2-4], and lightning discharges [e.g. 5]. Venusian lightning could potentially be volcanic in origin, since no meteorological mechanisms are known to separate charge effectively in its clouds [6]. The hunt for further evidence for lightning at Venus is ongoing, for example by means of the Lightning and Airglow Camera (LAC) [7] on Akatsuki, the current JAXA mission at Venus. Our laboratory experiments simulate ash generation and measure electrical charging of the ash under typical atmospheric conditions on Earth and Venus. The study uses a 1 litre chamber, which, when pressurised and heated, can simulate the high-pressure, high-temperature, carbon dioxide-dominated atmosphere of Venus at 10 km altitude ( 5 MPa, 650 K). A key finding of previous work [8] is that ash plume-forming eruptions are more likely to occur at higher altitudes such as these on Venus. The chamber contains temperature/pressure monitoring and logging equipment, a rock collision apparatus (based on [9]) to generate the charged rock fragments, and charge measurement electrodes connected

Link between the granitic and volcanic rocks of the Bushveld Complex, South Africa

NASA Astrophysics Data System (ADS)

Schweitzer, J. K.; Hatton, C. J.; De Waal, S. A.

1997-02-01

Until recently, it was proposed that the Bushveld Complex, consisting of the extrusive Rooiberg Group and the intrusive Rashoop Granophyre, Rustenburg Layered and Lebowa Granite Suites, evolved over a long period of time, possibly exceeding 100 Ma. Most workers therefore considered that the various intrusive and extrusive episodes were unrelated. Recent findings suggest that the intrusive, mafic Rustenburg Layered Suite, siliceous Rashoop Granophyre Suite and the volcanic Rooiberg Group were synchronous, implying that the Bushveld igneous event was short-lived. Accepting the short-lived nature of the complex, the hypothesis that the granites are genetically unrelated to the other events of the Bushveld Complex can be reconsidered. Re-examination of the potential Rooiberg Group/Lebowa Granite Suite relationship suggests that the granites form part of the Bushveld event. Rhyolite lava, granite and granophyre melts originated from a source similar in composition to upper crustal rocks. This source is interpreted to have been melted by a thermal input associated with a mantle plume. Granite intruded after extrusion of the last Rooiberg rhyolite, or possibly overlapped in time with the formation of the youngest volcanic flows.

Long-term global temperature variations under total solar irradiance, cosmic rays, and volcanic activity.

PubMed

Biktash, Lilia

2017-07-01

The effects of total solar irradiance (TSI) and volcanic activity on long-term global temperature variations during solar cycles 19-23 were studied. It was shown that a large proportion of climate variations can be explained by the mechanism of action of TSI and cosmic rays (CRs) on the state of the lower atmosphere and other meteorological parameters. The role of volcanic signals in the 11-year variations of the Earth's climate can be expressed as several years of global temperature drop. Conversely, it was shown that the effects of solar, geophysical, and human activity on climate change interact. It was concluded that more detailed investigations of these very complicated relationships are required, in order to be able to understand issues that affect ecosystems on a global scale.

Contemporaneous alkaline and calc-alkaline series in Central Anatolia (Turkey): Spatio-temporal evolution of a post-collisional Quaternary basaltic volcanism

NASA Astrophysics Data System (ADS)

Dogan-Kulahci, Gullu Deniz; Temel, Abidin; Gourgaud, Alain; Varol, Elif; Guillou, Hervé; Deniel, Catherine

2018-05-01

This study focuses on spatio-temporal evolution of basaltic volcanism in the Central Anatolian post-collisional Quaternary magmatic province which developed along a NE-SW orientation in Turkey. This magmatic province consists of the stratovolcanoes Erciyes (ES) and Hasandag (HS), and the basaltic volcanic fields of Obruk-Zengen (OZ) and Karapınar (KA). The investigated samples range between basic to intermediate in composition (48-56 wt% SiO2), and exhibit calc-alkaline affinity at ES whereas HS, OZ and KA are alkaline in composition. Based on new Ksbnd Ar ages and major element data, the oldest basaltic rock of ES is 1700 ± 40 ka old and exhibits alkaline character, whereas the youngest basaltic trachyandesite is 12 ± 5 ka old and calc-alkaline in composition. Most ES basaltic rocks are younger than 350 ka. All samples dated from HS are alkaline basalts, ranging from 543 ± 12 ka to 2 ± 7 ka old. With the exception of one basalt, all HS basalts are 100 ka or younger in age. Ksbnd Ar ages range from 797 ± 20 ka to 66 ± 7 ka from OZ. All the basalt samples are alkaline in character and are older than the HS alkaline basalts, with the exception of the youngest samples. The oldest and youngest basaltic samples from KA are 280 ± 7 ka and 163 ± 10 ka, respectively, and are calc-alkaline in character. Based on thermobarometric estimates samples from OZ exhibit the highest cpx-liqidus temperature and pressure. For all centers the calculated crystallization depths are between 11 and 28 km and increase from NE to SW. Multistage crystallization in magma chamber(s) located at different depths can explain this range in pressure. Harker variation diagrams coupled with least-squares mass balance calculations support fractional crystallization for ES and, to lesser extend for HS, OZ and KA. All basaltic volcanic rocks of this study are enriched in large-ion lithophile elements (LILE) and light rare earth elements (LREE). The lack of negative anomalies for high field

Diffuse H_{2} emission: a useful geochemical tool to monitor the volcanic activity at El Hierro volcano system

NASA Astrophysics Data System (ADS)

Pérez, Nemesio M.; Melián, Gladys; González-Santana, Judit; Barrancos, José; Padilla, Germán; Rodríguez, Fátima; Padrón, Eleazar; Hernández, Pedro A.

2016-04-01

The occurrence of interfering processes affecting reactive gases as CO2 during its ascent from magmatic bodies or hydrothermal systems toward the surface environment hinders the interpretation of their enrichments in the soil atmosphere and fluxes for volcano monitoring purposes (Marini and Gambardella, 2005). These processes include gas scrubbing by ground-waters and interaction with rocks, decarbonatation processes, biogenic production, etc. Within the rest of the soil gases, particularly interest has been addressed to light and highly mobile gases. They offer important advantages for the detection of vertical permeability structures, because their interaction with the surrounding rocks or fluids during the ascent toward the surface is minimum. H2 is one of the most abundant trace species in volcano-hydrothermal systems and is a key participant in many redox reactions occurring in the hydrothermal reservoir gas (Giggenbach, 1987). Although H2 can be produced in soils by N2-fixing and fertilizing bacteria, soils are considered nowadays as sinks of molecular hydrogen (Smith-Downey et al., 2006). Because of its chemical and physical characteristics, H2 generated within the crust moves rapidly and escapes to the atmosphere. These characteristics make H2 one of the best geochemical indicators of magmatic and geothermal activity at depth. El Hierro is the youngest and the SW-most of the Canary Islands and the scenario of the last volcanic eruption of the archipelago, a submarine eruption that took place 2 km off the southern coast of the island from October 2011 to March 2012. Since at El Hierro Island there are not any surface geothermal manifestations (fumaroles, etc), we have focused our studies on soil degassing surveys. Here we show the results of soil H2 emission surveys that have been carried out regularly since mid-2012. Soil gas samples were collected in ˜600 sites selected based on their accessibility and geological criteria. Soil gases were sampled at ˜40

Volcanic eruptions on Io

NASA Technical Reports Server (NTRS)

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

1981-01-01

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

The Volcanic History of Mars and Influences on Carbon Outgassing

NASA Astrophysics Data System (ADS)

Bleacher, J. E.; Whelley, P.

2015-12-01

Exploration of Mars has revealed some of the most impressive volcanic landforms found throughout the solar system. Volatiles outgassed from volcanoes were likely to have strongly influenced atmospheric chemistry and affected the martian climate. On Earth the role of carbon involved in volcanic outgassing is strongly influenced by tectonic setting, with the greatest weight percent contributions coming from partial mantle melts associated with hot spot volcanism. Most martian volcanic centers appear to represent this style of volcanism. Thus, one important factor in understanding the martian carbon cycle through time is understanding this volatile's link to the planet's volcanic history. The identified volcanic constructs on Mars are not unlike those of the Earth suggesting similar magmatic and eruptive processes. However, the dimensions of many martian volcanic features are significantly larger. The distribution of volcanoes and volcanic deposits on Mars are not spatially or temporally uniform. Large volcanoes (> 100 km diameter) are spatially concentrated in volcanic provinces that likely represent focused upwellings or zones of crustal weakness that enabled magma ascension. Smaller (10s km diameters) volcanoes such as cones, low shields and fissures are often grouped into fields and their lava flows coalesce to produce low slope plains. In some cases plains lava fields are quite extensive with little to no evidence for the volcanic constructs. Although martian volcanism appears to have been dominated by effusive eruptions with likely contributions from passive degassing from the interior, explosive volcanic centers and deposits are known to exist. After the development of a martian crust the planet's volcanic style appears to have evolved from early explosive activity to effusive activity centered at major volcanoes to effusive distributed activity in fields. However, questions remain as to whether or not these styles significantly overlapped in time and if so

Earth's youngest exposed granite and its tectonic implications: the 10–0.8 Ma Kurobegawa Granite

PubMed Central

Ito, Hisatoshi; Yamada, Ryuji; Tamura, Akihiro; Arai, Shoji; Horie, Kenji; Hokada, Tomokazu

2013-01-01

Although the quest for Earth's oldest rock is of great importance, identifying the youngest exposed pluton on Earth is also of interest. A pluton is a body of intrusive igneous rock that crystallized from slowly cooling magma at depths of several kilometers beneath the surface of the Earth. Therefore, the youngest exposed pluton represents the most recent tectonic uplift and highest exhumation. The youngest exposed pluton reported to date is the Takidani Granodiorite (~ 1.4 Ma) in the Hida Mountain Range of central Japan. Using LA-ICP-MS and SHRIMP U-Pb zircon dating methods, this study demonstrates that the Kurobegawa Granite, also situated in the Hida Mountain Range, is as young as ~ 0.8 Ma. In addition, data indicate multiple intrusion episodes in this pluton since 10 Ma with a ~ 2-million-year period of quiescence; hence, a future intrusion event is likely within 1 million years. PMID:23419636

Active Volcanic Plumes on Io

NASA Technical Reports Server (NTRS)

1997-01-01

This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera after a South American god of thunder, fire and volcanoes. The plume seen by Galileo is 140 kilometers (86 miles) high and was also detected by the Hubble Space Telescope. The Galileo spacecraft will pass almost directly over Pillan Patera in 1999 at a range of only 600 kilometers (373 miles).

The second plume, seen near the terminator (boundary between day and night), is called Prometheus after the Greek fire god (see inset at lower right). The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The vent is near the center of the bright and dark rings. Plumes on Io have a blue color, so the plume shadow is reddish. The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years. In contrast, a plume has never been seen at Pillan Patera prior to the recent Galileo and Hubble Space Telescope images.

North is toward the top of the picture. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 miles).

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

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page

Analysis of radar images of the active volcanic zone at Krafla, Iceland: The effects of look azimuth biasing

NASA Technical Reports Server (NTRS)

Garvin, J. B.; Williams, R. S., Jr.

1989-01-01

The geomorphic expression of Mid-Ocean-Ridge (MOR) volcanism in a subaerial setting occurs uniquely on Earth in Iceland, and the most recent MOR eruptive activity has been concentrated in the Northeastern Volcanic Zone in an area known as Krafla. Within the Krafla region are many of the key morphologic elements of MOR-related basaltic volcanism, as well as volcanic explosion craters, subglacial lava shields, tectonic fissure swarms known as gjar, and basaltic-andesite flows with well developed ogives (pressure-ridges). The objective was to quantify the degree to which the basic volcanic and structural features can be mapped from directional SAR imagery as a function of the look azimuth. To accomplish this, the current expression of volcanic and tectonic constructs was independently mapped within the Krafla region on the E, W, and N-looking SAR images, as well as from SPOT Panchromatic imagery acquired in 1987. The initial observations of the E, W, and N images indicates that fresh a'a lava surfaces are extremely radar bright (rough at 3 cm to meter scales) independent of look direction; this suggests that these flows do not have strong flow direction related structures at meter and cm scales, which is consistent with typical Icelandic a'a lava surfaces in general. The basic impression from a preliminary analysis of the effects of look azimuth biasing on interpretation of the geology of an active MOR volcanic zone is that up to 30 percent of the diagnostic features can be missed at any given look direction, but that having two orthogonal look direction images is probably sufficient to prevent gross misinterpretation.

Late Holocene volcanic activity and environmental change in Highland Guatemala

NASA Astrophysics Data System (ADS)

Lohse, Jon C.; Hamilton, W. Derek; Brenner, Mark; Curtis, Jason; Inomata, Takeshi; Morgan, Molly; Cardona, Karla; Aoyama, Kazuo; Yonenobu, Hitoshi

2018-07-01

We present a record of late Holocene volcanic eruptions with elemental data for a sequence of sampled tephras from Lake Amatitlan in Highland Guatemala. Our tephrochronology is anchored by a Bayesian P_Sequence age-depth model based on multiple AMS radiocarbon dates. We compare our record against a previously published study from the same area to understand the record of volcanism and environmental changes. This work has implications for understanding the effects of climate and other environmental changes that may be related to the emission of volcanic aerosols at local, regional and global scales.

Geochemical and geophysical monitoring activities in Campo de Calatrava Volcanic Field (Spain)

NASA Astrophysics Data System (ADS)

Luengo-Oroz, Natividad; Villasante-Marcos, Víctor; López-Díaz, Rubén; Calvo, Marta; Albert, Helena; Domínguez Cerdeña, Itahiza

2017-04-01

The Campo de Calatrava Volcanic Field (CCVF) or Spanish Central Volcanic Zone is located in central continental Spain (Ciudad Real province) and covers about 5000 km2. It includes around 240 eruptive centers, mainly monogenetic basaltic cones but also explosive maar structures. According to K-Ar geochronology, its main activity phase occurred during Pliocene and Pleistocene epochs (between 5 and 1.7 Ma) and involved alkaline to ultraalkaline magmas, although an older ultrapotassic phase is dated around 8.7-6.4 Ma. However, some recent works have proposed Holocene ages for some of the volcanic products, opening the possibility of considering the CCVF "active" according to international standards. Responding to this situation, the Instituto Geográfico Nacional (IGN) has initiated geochemical and geophysical monitoring activities in the CCVF. Here, we describe these ongoing efforts and we report results about groundwater geochemistry at several natural highly-gaseous springs in the area (hervideros), as well as soil temperature, CO2 diffuse flux from the soil and electrical self-potential data mapped on a small degassing structure called La Sima. In order to analyze microseismicity or any seismic anomaly in the CCVF, a seismic station has also been installed close to this degassing structure. Physicochemical parameters (temperature, pH, Eh and electric conductivity) were measured in situ in four springs and samples were taken in order to analyze major ions and trace elements. Total composition of dissolved gases and helium isotopic ratios were also determined. To complete soil temperature, self-potential and gas prospections performed in La Sima, soil gases were sampled at the bottom of the structure at a depth of 20 cm. Analysis of the total gas composition found 957400 ppm of CO2. Low values of O2 and N2 were also detected (5600 and 24800 ppm respectively).

Characterization of seismicity at Volcan Baru, Panama: May 2013 through April 2014

NASA Astrophysics Data System (ADS)

Hopp, Chet J.

Volcan Baru, in the western province of Chiriqui, is Panama's youngest and most active volcano. Although Baru has experienced no historic eruptions there have been four eruptive episodes in the last 1600 years, the most recent occurring 400-500 years ago (Sherrod et al., 2007). In addition, there have been four reported earthquake swarms in the last 100 years. The most recent swarm occurred in May of 2006, prompting a USGS hazard assessment (Sherrod et al., 2007). In order to characterize local seismicity and provide a reference for future monitoring efforts, we established a seismic network that operated from May 2013 through April 2014. The network consisted of eight temporary single-component, short-period sensors loaned by OSOP Panama, and three permanent stations distributed over a 35 by 15 km area. During operation of the network a catalog of 91 local events were detected, located and then used to calculate a minimum 1-D velocity model for Baru. Of particular interest were a cluster of events west of the town of Boquete. A template matching detection technique was used to identify another 47 smaller magnitude events in the area of this cluster. Spectrograms for the largest events in the cluster show a broad band of frequencies up to ˜20 Hz suggesting a predominantly tectonic source while eight focal mechanisms were calculated which suggest strike-slip and reverse faulting may be the predominant source processes. Further study is encouraged to better constrain the source processes and investigate how volcanic processes might affect local tectonics. 1. 1The material contained in this thesis is intended for submission to the Journal of Volcanology and Geothermal Research .

Preliminary geologic map of the Sleeping Butte volcanic centers

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

Crowe, B.M.; Perry, F.V.

1991-07-01

The Sleeping Butte volcanic centers comprise two, spatially separate, small-volume (<0.1 km{sup 3}) basaltic centers. The centers were formed by mildly explosive Strombolian eruptions. The Little Black Peak cone consists of a main scoria cone, two small satellitic scoria mounds, and associated lobate lava flows that vented from sites at the base of the scoria cone. The Hidden Cone center consists of a main scoria cone that developed on the north-facing slope of Sleeping Butte. The center formed during two episodes. The first included the formation of the main scoria cone, and venting of aa lava flows from radial dikesmore » at the northeast base of the cone. The second included eruption of scoria-fall deposits from the summit crater. The ages of the Little Black Peak and the Hidden Cone are estimated to be between 200 to 400 ka based on the whole-rock K-Ar age determinations with large analytical undertainty. This age assignment is consistent with qualitative observations of the degree of soil development and geomorphic degradation of volcanic landforms. The younger episode of the Hidden Cone is inferred to be significantly younger and probably of Late Pleistocene or Holocene age. This is based on the absence of cone slope rilling, the absence of cone-slope apron deposits, and erosional unconformity between the two episodes, the poor horizon- development of soils, and the presence of fall deposits on modern alluvial surfaces. Paleomagnetic data show that the centers record similar but not identical directions of remanent magnetization. Paleomagnetic data have not been obtained for the youngest deposits of the Hidden Cone center. Further geochronology, soils, geomorphic, and petrology studies are planned of the Sleeping Butte volcanic centers 20 refs., 3 figs.« less

Review of the Cambrian volcanic activity in Morocco: geochemical fingerprints and geotectonic implications for the rifting of West Gondwana

NASA Astrophysics Data System (ADS)

Pouclet, André; El Hadi, Hassan; Álvaro, J. Javier; Bardintzeff, Jacques-Marie; Benharref, Mohammed; Fekkak, Abdelilah

2018-03-01

Volcanic activities related to the opening of a Cambrian rift in Morocco were widespread from the Fortunian to the Cambrian Epoch 3. Numerous data are available from northwestern volcanic sites, particularly in the western High Atlas, but they are scarce from the southeastern sites. New data are documented here from the volcanic formations exposed in the Jbel Tazoult n'Ouzina of the Tafilalt Province, eastern Anti-Atlas and dated to Cambrian Epoch 2-3. The Cambrian volcanic activities recorded in the High Atlas, Anti-Atlas, and Coastal Meseta are synthesized to refine their stratigraphic setting and to characterize their magmatic affinities and fingerprints. Six volcanic pulses are determined as tholeiitic, transitional, and alkaline suites. The tholeiitic and transitional magmas originated from primitive mantle and E-MORB-type sources with a spinel- and garnet-bearing lherzolite composition. Some of them were modified by assimilation-fractional crystallisation processes during crust-mantle interactions. The alkaline magmas fit with an OIB-type and a garnet-bearing lherzolite source. The palaeogeographic distribution of the magmatic suites was controlled by the lithospheric thinning of the Cambrian Atlas Rift and lithospheric constraints of the Pan-African metacraton and West African craton.

Monitoring the Sumatra volcanic arc with InSAR

NASA Astrophysics Data System (ADS)

Chaussard, E.; Hong, S.; Amelung, F.

2009-12-01

The Sumatra volcanic arc is the result of the subduction of the Indo-Australian plate under the Sunda plate. The arc consists of 35 known volcanic centers, subaerials on the west coast of the Sumatra and Andaman Islands and submarines between these islands. Six active centers are known in the Sumatra volcanic arc. Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Here we present a satellite-based Interferometric synthetic aperture radar (InSAR) survey of the Sumatra volcanic arc using ALOS data. Spanning the years 2007 to beginning of 2009, our survey reveals the background level of activity of the 35 volcanoes. We processed data from 40 tracks (24 in descending orbit and 16 in ascending orbit) to cover the whole Sumatra arc. In the first results five of these six known active centers show no sign of activity: Dempo, Kaba, Marapi, Talang and Peuet. The remaining active volcano, Mount Kerinci, has an ambiguous signal. We used pair-wise logic and InSAR time series of the available ALOS data to determine if the observed InSAR signal is caused by ground deformation or by atmospheric delays.

Reconstructing an Explosive Basaltic Eruption in the Pinacate Volcanic Field, NW Sonora, Mexico

NASA Astrophysics Data System (ADS)

Zawacki, E. E.; Clarke, A. B.; Arrowsmith, R.; Lynch, D. J.

2017-12-01

Tephra deposits from explosive volcanic eruptions provide a means to reconstruct eruption characteristics, such as column height and erupted volume. Parameters like these are essential in assessing the explosivity of past eruptions and associated volcanic hazards. We applied such methods to a basaltic tephra deposit from one of the youngest eruptions in the Pinacate volcanic field (NW Sonora, Mexico). This roughly circular tephra blanket extends 13 km E-W and 13 km N-S, and covers an area of at least 135 km2. The source vent of this eruption is hypothesized to be the Tecolote volcano (lat 31.877, long -113.362), which is dated to 27 ± 6 ka (40Ar/39Ar). Fifty-three pits were dug across the extent of the tephra deposit to measure its thickness, record stratigraphy, characterize grain size distribution, and determine maximum clast size. Isopleth and isopach maps were created from these data to determine the column height (>9 km), estimate mass eruption rate (>2.1x106 kg/s), and calculate the erupted volume (>4.2x10-2 km3). Stratigraphic descriptions support two distinct episodes of tephra production. Unit A is dispersed in an approximately circular pattern ( 6.5 km radius) with its center shifted to the east of the vent. The distribution of Unit B is oblate ( 9.5 km major axis, 4.5 km minor axis) and trends to the southeast of the vent. Lava samples were collected from each of the seven Tecolote flows for XRF and ICP-MS geochemical analyses. These samples were compared to geochemical signatures from a Tecolote bomb, tephra from Units A and B, and cinder from the La Laja cone, which is the youngest dated cone in the field at 12 ± 4 ka (40Ar/39Ar). The La Laja sample is geochemically distinct from all Tecolote samples, confirming that it did not contribute to the two tephra units. Tephra from Unit A and Unit B have distinct signatures and fit within the geochemical evolution of the Tecolote lavas, supporting two explosive episodes from the Tecolote volcano, which has

Volcanic history and 40Ar/39Ar and 14C geochronology of Terceira Island, Azores, Portugal

USGS Publications Warehouse

Calvert, Andrew T.; Moore, Richard B.; McGeehin, John P.; Rodrigues da Silva, Antonio

2006-01-01

Seven new 40Ar/39Ar and 23 new radiocarbon ages of eruptive units, in support of new geologic mapping, improve the known chronology of Middle to Late Pleistocene and Holocene volcanic activity on the island of Terceira, Azores and define an east-to-west progression in stratovolcano growth. The argon ages indicate that Cinco Picos Volcano, the oldest on Terceira, completed its main subaerial cone building activity by about 370–380 ka. Collapse of the upper part of the stratovolcanic edifice to form a 7 × 9 km caldera occurred some time after 370 ka. Postcaldera eruptions of basalt from cinder cones on and near the caldera floor and trachytic pyroclastic flow and pumice fall deposits from younger volcanoes west of Cinco Picos have refilled much of the caldera. The southern portion of Guilherme Moniz Volcano, in the central part of the island, began erupting prior to 270 ka and produced trachyte domes, flows, and minor pyroclastic deposits until at least 111 ka. The northern part of Guilherme Moniz Caldera is less well exposed than the southern part, but reflects a similar age range. The northwest portion of the caldera was formed sometime after 44 ka. Several well-studied ignimbrites that blanket much of the island likely erupted from Guilherme Moniz Volcano. The Pico Alto Volcanic Center, a tightly spaced cluster of trachyte domes and short flows, is a younger part of Guilherme Moniz Volcano. Stratigraphic studies and our new radiocarbon ages suggest that most of the Pico Alto eruptions occurred during the period from about 9000 to 1000 years BP. Santa Barbara Volcano is the youngest stratovolcano on Terceira, began erupting prior to 29 ka, and has been active historically.

Stable isotope geochemistry of fumaroles: an insight into volcanic surveillance

NASA Astrophysics Data System (ADS)

Panichi, C.; La Ruffa, G.

2001-12-01

In active volcanic environments magmatic water may accumulate in the volcanic-hosted geothermal systems, or, more rarely may reach the surface along deep fractures inside the volcano crater. Knowledge of magmatic contribution to emerging fluids in volcanic active areas is critical to understanding the chemical evolution of the magma, the conditions in which it exists in the crust, and the mechanisms by which it erupts in the crust. The source of volatiles (especially water) is also of interest when eruptions are driven by the expansion of hydrothermal fluids against atmospheric pressure, without the involvement of fresh magma ('hydrothermal' or 'phreatomagmatic' eruptions). In both cases the occurrence of volcanic and/or phreatic activities is likely to be preceded by substantial isotopic and chemical changes in the crater fumarolic systems. H and O isotopic composition of condensed water from crater fumaroles appear to be able to give strong evidence for the existence of magmatic waters in the high-temperature manifestations of the volcanic systems. Isotopic data and specific hydrological models from seven different volcanic systems (Galeras Volcano, Colombia, Kilauea Volcano, Hawaii, Kudryvy Volcano, Kuril volcanic arc, Mt St Helens, USA; Guagua Pichincha, Ecuador; Vulcano island, Italy; the Aegean Volcanic Arc, Greece) are discussed in order to highlight the possibility to use those isotopic parameters in the assessment of the environmental risks of an active volcanic area.

A brief Oligocene period of flood volcanism in Yemen: implications for the duration and rate of continental flood volcanism at the Afro-Arabian triple junction

NASA Astrophysics Data System (ADS)

Baker, Joel; Snee, Lawrence; Menzies, Martin

1996-02-01

40Ar/39Ar dating of mineral separates and whole-rock (WR) samples has established that basaltic continental flood volcanism (CFV) began between 30.9 and 29.2 Ma in northwestern and southwestern Yemen, respectively. Rhyolitic volcanism commenced at 29.0-29.3 Ma throughout Yemen. Lower basaltic lavas were erupted every 10-100 kyr, whereas upper bimodal volcanic units were erupted every 100-500 kyr, which reflects generation of rhyolitic magmas from basalts that resided for longer periods in lithospheric magma chambers than during the early phase of exclusively mafic magmatism. The youngest dated flood volcanic units were erupted between 26.9 and 26.5 Ma throughout Yemen. The duration of preserved CFV defined by 40Ar/39Ar dating (4.4 myr) contrasts with the wide range of WR KAr dates previously obtained in Yemen (> 50 myr). 40Ar/39Ar step-heating studies of WR samples has shown that this discrepancy is due to the disturbed Ar systematics of volcanic samples. Most samples have experienced post-crystallization loss of radiogenic Ar and/or contain excess Ar, with only ca. 25% of the WR KAr dates within 1-2 myr of true crystallization ages. WR KAr data can be screened for reliability using the radiogenic Ar yield and 40K/36Ar ratio, which reflect the Ar retentivity of the sample, the likelihood that alteration has disturbed a sample's Ar systematics, and the susceptibility of the sample to a finite amount of Ar loss or the presence of a finite amount of excess Ar. Examination of existing WR KAr data in the Ethiopian part of this flood volcanic province, using these parameters, suggests that much of these data are also misleading. Two phases of flood volcanism are inferred in Ethiopia and Eritrea at 38-30 Ma and ca. 20 Ma. The older phase is equivalent to that in Yemen, and is consistent with the progression in basal volcanic ages obtained in Yemen moving from north to south. The younger phase is related to the onset of upper crustal extension and incipient Red

A brief Oligocene period of flood volcanism in Yemen: Implications for the duration and rate of continental flood volcanism at the Afro-Arabian triple junction

USGS Publications Warehouse

Baker, J.; Snee, L.; Menzies, M.

1996-01-01

40Ar39Ar dating of mineral separates and whole-rock (WR) samples has established that basaltic continental flood volcanism (CFV) began between 30.9 and 29.2 Ma in northwestern and southwestern Yemen, respectively. Rhyolitic volcanism commenced at 29.3-29.0 Ma throughout Yemen. Lower basaltic lavas were erupted every 10-100 kyr, whereas upper bimodal volcanic units were erupted every 100-500 kyr, which reflects generation of rhyolitic magmas from basalts that resided for longer periods in lithospheric magma chambers than during the early phase of exclusively mafic magmatism. The youngest dated flood volcanic units were erupted between 26.9 and 26.5 Ma throughout Yemen. The duration of preserved CFV defined by 40Ar/39Ar dating (4.4 myr) contrasts with the wide range of WR K-Ar dates previously obtained in Yemen (> 50 myr). 40Ar/39Ar step-heating studies of WR samples has shown that this discrepancy is due to the disturbed Ar systematics of volcanic samples. Most samples have experienced post-crystallization loss of radiogenic Ar and/or contain excess Ar, with only ca. 25% of the WR K-Ar dates within 1-2 myr of true crystallization ages. WR K-Ar data can be screened for reliability using the radiogenic Ar yield and 40K/36Ar ratio, which reflect the Ar retentivity of the sample, the likelihood that alteration has disturbed a sample's Ar systematics, and the susceptibility of the sample to a finite amount of Ar loss or the presence of a finite amount of excess Ar. Examination of existing WR K-Ar data in the Ethiopian part of this flood volcanic province, using these parameters, suggests that much of these data are also misleading. Two phases of flood volcanism are inferred in Ethiopia and Eritrea at 38-30 Ma and ca. 20 Ma. The older phase is equivalent to that in Yemen, and is consistent with the progression in basal volcanic ages obtained in Yemen moving from north to south. The younger phase is related to the onset of upper crustal extension and incipient Red Sea

Mainshock-aftershock clustering in volcanic regions

USGS Publications Warehouse

Giron, Ricardo Garza; Brodsky, Emily E.; Prejean, Stephanie

2018-01-01

swarms and mainshock-aftershock sequences. The former is commonly thought to dominate in volcanic and geothermal regions, but aftershock production, including within swarms, is not well studied in volcanic regions. Here we compare mainshock-aftershock clustering in active volcanic regions in Japan to nearby nonvolcanic regions. We find that aftershock production is similar in both areas by two separate metrics: (1) Both volcanic and nonvolcanic regions have similar proportions of areas that cluster into mainshock-aftershock sequences. (2) Volcanic areas with mainshock-aftershock sequences have aftershock productivity at least as high as nonvolcanic regions. We also find that volcano-tectonic events that are precursors to an eruption are more common at volcanoes without mainshock-aftershock clusters than at volcanoes with well-defined mainshock-aftershock clusters. This last finding hints at a strategy to identify volcanic systems where cataloged earthquakes are good predictors of behavior.

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

USGS Publications Warehouse

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

2014-01-01

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

Tertiary volcanic rocks and uranium in the Thomas Range and northern Drum Mountains, Juab County, Utah

USGS Publications Warehouse

Lindsey, David A.

1982-01-01

The Thomas Range and northern Drum Mountains have a history of volcanism, faulting, and mineralization that began about 42 m.y. (million years) ago. Volcanic activity and mineralization in the area can be divided into three stages according to the time-related occurrence of rock types, trace-element associations, and chemical composition of mineral deposits. Compositions of volcanic rocks changed abruptly from rhyodacite-quartz latite (42-39 m.y. ago) to rhyolite (38-32 m.y. ago) to alkali rhyolite (21 and 6-7 m.y. ago); these stages correspond to periods of chalcophile and siderophile metal mineralization, no mineralization(?), and lithophile metal mineralization, respectively. Angular unconformities record episodes of cauldron collapse and block faulting between the stages of volcanic activity and mineralization. The youngest angular unconformity formed between 21 and 7 m.y. ago during basin-and-range faulting. Early rhyodacite-quartz latite volcanism from composite volcanoes and fissures produced flows, breccias, and ash-flow tuff of the Drum Mountains Rhyodacite and Mt. Laird Tuff. Eruption of the Mt. Laird Tuff about 39 m.y. ago from an area north of Joy townsite was accompanied by collapse of the Thomas caldera. Part of the roof of the magma chamber did not collapse, or the magma was resurgent, as is indicated by porphyry dikes and plugs in the Drum Mountains. Chalcophile and siderophile metal mineralization, resulting in deposits of copper, gold, and manganese, accompanied early volcanism. Te middle stage of volcanic activity was characterized by explosive eruption of rhyolitic ash-flow tuffs and collapse of the Dugway Valley cauldron. Eruption of the Joy Tuff 38 m.y. ago was accompanied by subsidence of this cauldron and was followed by collapse and sliding of Paleozoic rocks from the west wall of the cauldron. Landslides in The Dell were covered by the Dell Tuff, erupted 32 m.y. ago from an unknown source to the east. An ash flow of the Needles Range

Volcanic activity at Tvashtar Catena, Io

USGS Publications Warehouse

Milazzo, M.P.; Keszthelyi, L.P.; Radebaugh, J.; Davies, A.G.; Turtle, E.P.; Geissler, P.; Klaasen, K.P.; Rathbun, J.A.; McEwen, A.S.

2005-01-01

Galileo's Solid State Imager (SSI) observed Tvashtar Catena four times between November 1999 and October 2001, providing a unique look at a distinctive high latitude volcanic complex on Io. The first observation (orbit I25, November 1999) resolved, for the first time, an active extraterrestrial fissure eruption; the brightness temperature was at least 1300 K. The second observation (orbit I27, February 2000) showed a large (??? 500 km 2) region with many, small, hot, regions of active lava. The third observation was taken in conjunction with Cassini imaging in December 2000 and showed a Pele-like, annular plume deposit. The Cassini images revealed an ???400 km high Pele-type plume above Tvashtar Catena. The final Galileo SSI observation of Tvashtar (orbit I32, October 2001), revealed that obvious (to SSI) activity had ceased, although data from Galileo's Near Infrared Mapping Spectrometer (NIMS) indicated that there was still significant thermal emission from the Tvashtar region. In this paper, we primarily analyze the style of eruption during orbit I27 (February 2000). Comparison with a lava flow cooling model indicates that the behavior of the Tvashtar eruption during I27 does not match that of simple advancing lava flows. Instead, it may be an active lava lake or a complex set of lava flows with episodic, overlapping eruptions. The highest reliable color temperature is ???1300 K. Although higher temperatures cannot be ruled out, they do not need to be invoked to fit the observed data. The total power output from the active lavas in February 2000 was at least 1011 W. ?? 2005 Elsevier Inc. All rights reserved.

Acoustic waves in the atmosphere and ground generated by volcanic activity

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

Ichihara, Mie; Lyons, John; Oikawa, Jun

2012-09-04

This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted alsomore » to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.« less

The Cenozoic volcanism in the Kivu rift: Assessment of the tectonic setting, geochemistry, and geochronology of the volcanic activity in the South-Kivu and Virunga regions

NASA Astrophysics Data System (ADS)

Pouclet, A.; Bellon, H.; Bram, K.

2016-09-01

The Kivu rift is part of the western branch of the East African Rift system. From Lake Tanganyika to Lake Albert, the Kivu rift is set in a succession of Precambrian zones of weakness trending NW-SE, NNE-SSW and NE-SW. At the NW to NNE turn of the rift direction in the Lake Kivu area, the inherited faults are crosscut by newly born N-S fractures which developed during the late Cenozoic rifting and controlled the volcanic activity. From Lake Kivu to Lake Edward, the N-S faults show a right-lateral en echelon pattern. Development of tension gashes in the Virunga area indicates a clockwise rotation of the constraint linked to dextral oblique motion of crustal blocks. The extensional direction was W-E in the Mio-Pliocene and ENE-WSW in the Pleistocene to present time. The volcanic rocks are assigned to three groups: (1) tholeiites and sodic alkali basalts in the South-Kivu, (2) sodic basalts and nephelinites in the northern Lake Kivu and western Virunga, and (3) potassic basanites and potassic nephelinites in the Virunga area. South-Kivu magmas were generated by melting of spinel + garnet lherzolite from two sources: an enriched lithospheric source and a less enriched mixed lithospheric and asthenospheric source. The latter source was implied in the genesis of the tholeiitic lavas at the beginning of the South-Kivu tectono-volcanic activity, in relationships with asthenosphere upwelling. The ensuing outpouring of alkaline basaltic lavas from the lithospheric source attests for the abortion of the asthenospheric contribution and a change of the rifting process. The sodic nephelinites of the northern Lake Kivu originated from low partial melting of garnet peridotite of the sub-continental mantle due to pressure release during swell initiation. The Virunga potassic magmas resulted from the melting of garnet peridotite with an increasing degree of melting from nephelinite to basanite. They originated from a lithospheric source enriched in both K and Rb, suggesting the

Seismic evidence for arc segmentation, active magmatic intrusions and syn-rift fault system in the northern Ryukyu volcanic arc

NASA Astrophysics Data System (ADS)

Arai, Ryuta; Kodaira, Shuichi; Takahashi, Tsutomu; Miura, Seiichi; Kaneda, Yoshiyuki

2018-04-01

Tectonic and volcanic structures of the northern Ryukyu arc are investigated on the basis of multichannel seismic (MCS) reflection data. The study area forms an active volcanic front in parallel to the non-volcanic island chain in the eastern margin of the Eurasian plate and has been undergoing regional extension on its back-arc side. We carried out a MCS reflection experiment along two across-arc lines, and one of the profiles was laid out across the Tokara Channel, a linear bathymetric depression which demarcates the northern and central Ryukyu arcs. The reflection image reveals that beneath this topographic valley there exists a 3-km-deep sedimentary basin atop the arc crust, suggesting that the arc segment boundary was formed by rapid and focused subsidence of the arc crust driven by the arc-parallel extension. Around the volcanic front, magmatic conduits represented by tubular transparent bodies in the reflection images are well developed within the shallow sediments and some of them are accompanied by small fragments of dipping seismic reflectors indicating intruded sills at their bottoms. The spatial distribution of the conduits may suggest that the arc volcanism has multiple active outlets on the seafloor which bifurcate at crustal depths and/or that the location of the volcanic front has been migrating trenchward over time. Further distant from the volcanic front toward the back-arc (> 30 km away), these volcanic features vanish, and alternatively wide rift basins become predominant where rapid transitions from normal-fault-dominant regions to strike-slip-fault-dominant regions occur. This spatial variation in faulting patterns indicates complex stress regimes associated with arc/back-arc rifting in the northern Okinawa Trough.[Figure not available: see fulltext.

Mainshock-Aftershock Clustering in Volcanic Regions

NASA Astrophysics Data System (ADS)

Garza-Giron, Ricardo; Brodsky, Emily E.; Prejean, Stephanie G.

2018-02-01

Earthquakes break their general Poissonean behavior through two types of seismic bursts: swarms and mainshock-aftershock sequences. The former is commonly thought to dominate in volcanic and geothermal regions, but aftershock production, including within swarms, is not well studied in volcanic regions. Here we compare mainshock-aftershock clustering in active volcanic regions in Japan to nearby nonvolcanic regions. We find that aftershock production is similar in both areas by two separate metrics: (1) Both volcanic and nonvolcanic regions have similar proportions of areas that cluster into mainshock-aftershock sequences. (2) Volcanic areas with mainshock-aftershock sequences have aftershock productivity at least as high as nonvolcanic regions. We also find that volcano-tectonic events that are precursors to an eruption are more common at volcanoes without mainshock-aftershock clusters than at volcanoes with well-defined mainshock-aftershock clusters. This last finding hints at a strategy to identify volcanic systems where cataloged earthquakes are good predictors of behavior.

Volcanic processes in the Solar System

USGS Publications Warehouse

Carr, M.H.

1987-01-01

This article stresses that terrestrial volcanism represents only part of the range of volcanism in the solar system. Earth processes of volcanicity are dominated by plate tectonics, which does not seem to operate on other planets, except possibly on Venus. Lunar volcanicity is dominated by lava effusion at enormous rates. Mars is similar, with the addition to huge shield volcanoes developed over fixed hotspots. Io, the moon closest to Jupiter, is the most active body in the Solar System and, for example, much sulphur and silicates are emitted. The eruptions of Io are generated by heating caused by tides induced by Jupiter. Europa nearby seems to emit water from fractures and Ganymede is similar. The satellites of Saturn and Uranus are also marked by volcanic craters, but they are of very low temperature melts, possibly of ammonia and water. The volcanism of the solar system is generally more exotic, the greater the distance from Earth. -A.Scarth

Volcanic gas

USGS Publications Warehouse

McGee, Kenneth A.; Gerlach, Terrance M.

1995-01-01

In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

Igneous activity and related ore deposits in the western and southern Tushar Mountains, Marysvale volcanic field, west-central Utah

USGS Publications Warehouse

Steven, Thomas A.

1984-01-01

PART A: Igneous activity in the Marysvale volcanic field of western Utah can be separated into many episodes of extrusion, intrusion, and hydrothermal activity. The rocks of the western Tushar Mountains, near the western part of the volcanic field, include intermediate-composition, calc-alkalic volcanic rocks erupted from scattered volcanoes in Oligocene through earliest Miocene time and related monzonitic intrusions emplaced 24-23 m.y. ago. Beginning 22-21 m.y. ago and extending through much of the later Cenozoic, a bimodal basalt-rhyolite assemblage was erupted widely throughout the volcanic field. Only volcanic and intrusive rocks belonging to the rhyolitic end member of this bimodal assemblage are present in the western Tushar Mountains; most of these rocks either fill the Mount Belknap caldera (19 m.y. old) or are part of the rhyolite of Gillies Hill (9---8 m.y. old). Episodic hydrothermal activity altered and mineralized rocks at many places in the western Tushar Mountains during Miocene time. The earliest activity took place in and adjacent to monzonitic calcalkalic intrusions emplaced in the vicinity of Indian Creek and Cork Ridge. These rocks were widely propylitized, and gold-bearing quartz-pyrite-carbonate veins formed in local fractures. Hydrothermal activity associated with the Mount Belknap caldera mobilized and redeposited uranium contained in the caldera-fill rocks and formed primary concentrations of lithophile elements (including molybdenum and uranium) in the vicinity of intrusive bodies. Hydrothermal activity associated with the rhyolite of Gillies Hill altered and mineralized rocks at several places along the fault zone that marks the western margin of the Tushar Mountains; the zoned alunite and gold deposits at Sheep Rock, the gold deposit at the Sunday Mine, and an alunite deposit near Indian Creek were thus produced. Resetting of isotopic ages suggests that another center of hydrothermally altered rocks associated with a buried pluton about

Stratigraphy, facies architecture, and palaeoenvironment of Neoproterozoic volcanics and volcaniclastic deposits in Fatira area, Central Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

Khalaf, Ezz El Din Abdel Hakim

Fatira area in the Central Eastern Desert, Egypt, is a composite terrane consisting of Neoproterozoic volcanics and sediments laid down in submarine to subaerial environment, intruded by voluminous old to young granitic rocks. The various lithofacies of the study area can be grouped in three distinct lithostratigraphic sequences, which are described here in stratigraphic order, from base to top as the Fatira El Beida, Fatira El Zarqa and Gabal Fatira sequences. Each depositional sequence, is intimately related to volcanic activity separated by time intervals of volcanic inactivity, such as marked hiatuses, reworked volcaniclasts, and or turbidite sedimentation. Four submarine facies groups have been recognized within the oldest, folded eruption sequence of Fatira El Beida. The southern part of the study area is occupied by sheet lava (SL), pillow lavas (PL), pillow breccias (PB), and overlying Bouma turbiditic volcaniclastites (VC). The four facies groups of Fatira El Beida sequence occur in a predictable upward-deepening succession, essentially from base to top, an SL-PL-PB-VC stacking pattern. The coeval tholeiitic mafic and felsic volcaniclastic rocks of this sequence indicate an extensional back-arc tectonic setting. The El Beida depositional sequence appears to fit a submarine-fan and slope-apron environment in an intra-arc site. The Fatira El Zarqa sequence involves a large volume of subaerial calc-alkaline intermediate to felsic volcanics and an unconformably overlying siliciclastic succession comprising clast-supported conglomerates (Gm), massive sandstone sheet floods (Sm) and mudstones (FI), together with a lateritic argillite paleosol (P) top formed in an alluvial-fan system. The youngest rock of Gabal Fatira sequence comprises anorogenic trachydacites and rhyolites with locally emergent domes associated with autobrecciation and sill-dyke rock swarms that could be interpreted as feeders and subvolcanic intrusions. Unconformity and lithofacies assemblages

Geophysical Investigations on a Suspected Quarternary Volcanic Structure in North Eastern Bavaria, Germany

NASA Astrophysics Data System (ADS)

Geiss, E.; Rohrmüller, J.; Wassermann, J.; Hackl, M.; Kirscher, U.; Bachtadse, V.

2012-04-01

Recent geophysical studies on a small scale morphological depression northwest of the Zelezná hurka scoria cone (Eisenbühl, 49.99°N/12.45°E) near the village of Mytina (Czech Republic) revealed the presence of a maar-diatreme, filled with volcanic material and covered by alluvium. Reported Ar/Ar ages of 288 ± 17 ka imply that formation of the Mytina maar and emplacement of the Zelezná hurka might represent the youngest volcanic event in Central Europe, east of the volcanic Eifel province. If the interpretation that both the Mytina maar and the Zelezná hurka scoria cone are situated on the NW-SE striking Tachov Fault Zone south of the Cheb basin is correct, similar volcanic structures can be assumed to the west of the Czech-German border only a couple of km away from Mytina. Here we report the results of a combined gravity, magnetic, geoelectric and seismic survey carried out across a topographic depression situated along strike of the Tachov Fault Zone near the town of Neualbenreuth, eastern Bavaria. The local gravity field was determined at 120 data points covering roughly 10 square km. The Bouguer and topographically corrected gravity data show a very distinct isometric low of -2.84 mgals in an area of ~300x400m which coincides with the topographic depression in the center of the studied area. The resulting model of the density distribution in the underground is consistent with a maar-diatreme with rather low density rocks in the central vent. The structure has been modelled in 3D using IGMAS software. Geoelectrical measurements indicate low resistivity in the vent and higher porosity in the vent filling. However, magnetic data and seismic profiles across the postulated maar-diatreme do not strengthen our hypothesis and are inconclusive.

Infrasound Monitoring of the Volcanic Activities of Japanese Volcanoes in Korea

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

A spaceborne inventory of volcanic activity in Antarctica and southern oceans, 2000-10

USGS Publications Warehouse

Patrick, Matthew R.; Smellie, John L.

2015-01-01

Of the more than twenty historically active volcanoes in Antarctica and the sub-Antarctic region only two, to our knowledge, host any ground-based monitoring instruments. Moreover, because of their remoteness, most of the volcanoes are seldom visited, thus relegating the monitoring of volcanism in this region almost entirely to satellites. In this study, high temporal resolution satellite data from the Hawaii Institute of Geophysics and Planetology's MODVOLC system using MODIS (Moderate Resolution Imaging Spectroradiometer) are complemented with high spatial resolution data (ASTER, or Advanced Spaceborne Thermal Emission and Reflection Radiometer, and similar sensors) to document volcanic activity throughout the region during the period 2000–10. Five volcanoes were observed in eruption (Mount Erebus, Mount Belinda, Mount Michael, Heard Island and McDonald Island), which were predominantly low-level and effusive in nature. Mount Belinda produced tephra, building a cinder cone in addition to an extensive lava field. Five volcanoes exhibited detectable thermal, and presumed fumarolic, activity (Deception, Zavodovski, Candlemas, Bristol, and Bellingshausen islands). A minor eruption reported at Marion Island was not detected in our survey due to its small size. This study also discovered a new active vent on Mount Michael, tracked dramatic vent enlargement on Heard Island, and provides an improved picture of the morphology of some of the volcanoes.

Can we detect, monitor, and characterize volcanic activity using 'off the shelf' webcams and low-light cameras?

NASA Astrophysics Data System (ADS)

Harrild, M.; Webley, P. W.; Dehn, J.

2015-12-01

The ability to detect and monitor precursory events, thermal signatures, and ongoing volcanic activity in near-realtime is an invaluable tool. Volcanic hazards often range from low level lava effusion to large explosive eruptions, easily capable of ejecting ash to aircraft cruise altitudes. Using ground based remote sensing to detect and monitor this activity is essential, but the required equipment is often expensive and difficult to maintain, which increases the risk to public safety and the likelihood of financial impact. Our investigation explores the use of 'off the shelf' cameras, ranging from computer webcams to low-light security cameras, to monitor volcanic incandescent activity in near-realtime. These cameras are ideal as they operate in the visible and near-infrared (NIR) portions of the electromagnetic spectrum, are relatively cheap to purchase, consume little power, are easily replaced, and can provide telemetered, near-realtime data. We focus on the early detection of volcanic activity, using automated scripts that capture streaming online webcam imagery and evaluate each image according to pixel brightness, in order to automatically detect and identify increases in potentially hazardous activity. The cameras used here range in price from 0 to 1,000 and the script is written in Python, an open source programming language, to reduce the overall cost to potential users and increase the accessibility of these tools, particularly in developing nations. In addition, by performing laboratory tests to determine the spectral response of these cameras, a direct comparison of collocated low-light and thermal infrared cameras has allowed approximate eruption temperatures to be correlated to pixel brightness. Data collected from several volcanoes; (1) Stromboli, Italy (2) Shiveluch, Russia (3) Fuego, Guatemala (4) Popcatépetl, México, along with campaign data from Stromboli (June, 2013), and laboratory tests are presented here.

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

NASA Astrophysics Data System (ADS)

Robidoux, Philippe; Aiuppa, Alessandro; Conde, Vladimir; Galle, Bo; Giudice, Gaetano; Avard, Geoffroy; Muñoz, Angélica

2014-05-01

CO2 is a key chemical tracer for exploring volcanic degassing mechanisms of basaltic magmatic systems (1). The rate of CO2 release from sub-aerial volcanism is monitored via studies on volcanic plumes and fumaroles, but information is still sparse and incomplete for many regions of the globe, including the majority of the volcanoes in the Central American Volcanic Arc (2). Here, we use a combination of remote sensing techniques and in-situ measurements of volcanic gas plumes to provide a first estimate of the CO2 output from three degassing volcanoes in Central America: Turrialba, in Costa Rica, and Telica and San Cristobal, in Nicaragua. During a field campaign in March-April 2013, we obtained (for the three volcanoes) a simultaneous record of SO2 fluxes (from the NOVAC network (3)) and CO2 vs. SO2 concentrations in the near-vent plumes (obtained via a temporary installed fully-automated Multi-GAS instrument (4)). The Multi-GAS time-series allowed to calculate the plume CO2/SO2 ratios for different intervals of time, showing relatively stable gas compositions. Distinct CO2 - SO2 - H2O proportions were observed at the three volcanoes, but still within the range of volcanic arc gas (5). The CO2/SO2 ratios were then multiplied by the SO2 flux in order to derive the CO2 output. At Turrialba, CO2/SO2 ratios fluctuated, between March 12 and 19, between 1.1 and 5.7, and the CO2flux was evaluated at ~1000-1350 t/d (6). At Telica, between March 23 and April 8, a somewhat higher CO2/SO2 ratio was observed (3.3 ± 1.0), although the CO2 flux was evaluated at only ~100-500 t/d (6). At San Cristobal, where observations were taken between April 11 and 15, the CO2/SO2 ratio ranged between 1.8 and 7.4, with a mean CO2 flux of 753 t/d. These measurements contribute refining the current estimates of the total CO2 output from the Central American Volcanic Arc (7). Symonds, R.B. et al., (2001). J. Volcanol. Geotherm. Res., 108, 303-341 Burton, M. R. et al. (2013). Reviews in

Volcanism on Mars

NASA Astrophysics Data System (ADS)

Head, J. W.

1981-11-01

Characterization of volcanic activity on Mars is reviewed and comparisons are made with knowledge of terrestrial volcanic history. The high frequency of calderas on earth and low abundance on Mars is taken to indicate a lack of plate tectonic subduction zones and silicic volcanism on Mars. Further characterization is noted to depend on remote sensing from Viking orbital and earth-based spectral and albedo data. Theoretical models of causative mechanisms of terrestrial morphology will be used to establish models of similar processes on Mars, including deposits identification, eruptive conditions, and theories of magma ascent, as well as the role of volatiles from both deep and shallow sources. The importance of returning to Mars with appropriately instrumented spacecraft to test the new theories is stressed. The topics were discussed in papers presented at the Mars colloquium at the California Institute of Technology in August, 1981.

Volcanic complexes in the eastern ridge of the Canary Islands: the Miocene activity of the island of Fuerteventura

NASA Astrophysics Data System (ADS)

Ancochea, E.; Brändle, J. L.; Cubas, C. R.; Hernán, F.; Huertas, M. J.

1996-03-01

Fuerteventura has been since early stages of its growth the result of three different adjacent large volcanic complexes: Southern, Central and Northern. The definition of these volcanic complexes and their respective growing episodes is based on volcano-stratigraphic, morphological and structural criteria, particularly radial dyke swarms. Each complex has its own prolonged history that might be longer than 10 m.y. During that time, several periods of activity alternating with gaps accompanied by important erosion took place. The evolution of each volcanic complex has been partially independent but all the three are affected by at least three Miocene tectonic phases that controlled considerably their activity. The volcanic complexes are deeply eroded and partially submerged. In the core of the Northern and the Central volcanic complexes there is a set of submarine and plutonic rocks intensely traversed by a dyke swarm, known as the Basal Complex. The Basal Complex has been interpreted in different ways but all previous authors have considered it to be prior to the subaerial shield stage of the island. Here we advance the idea that the Basal Complex represent the submarine growing stage of the volcanic complexes and the hypabyssal roots (plutons and dykes) of their successive subaerial growing episodes. Two seamounts situated nearby, southwest of the island, might be interpreted as remains of two other major volcanoes. These two volcanoes, together with those forming the present emerged island of Fuerteventura, and finally those of Famara and Los Ajaches situated further north on Lanzarote constitute a chain of volcanoes located along a lineation which is subparallel to the northwestern African coastline and which may relate to early Atlantic spreading trends in the area.

Venus - Volcanic features in Atla Region

NASA Technical Reports Server (NTRS)

1991-01-01

This Magellan image from the Atla region of Venus shows several types of volcanic features and superimposed surface fractures. The area in the image is approximately 350 kilometers (217 miles) across, centered at 9 degrees south latitude, 199 degrees east longitude. Lava flows emanating from circular pits or linear fissures form flower-shaped patterns in several areas. A collapse depression approximately 20 kilometers by 10 kilometers (12 by 6 miles) near the center of the image is drained by a lava channel approximately 40 kilometers (25 miles) long. Numerous surface fractures and graben (linear valleys) criss-cross the volcanic deposits in north to northeast trends. The fractures are not buried by the lavas, indicating that the tectonic activity post-dates most of the volcanic activity.

The Volcanism Ontology (VO): a model of the volcanic system

NASA Astrophysics Data System (ADS)

Myer, J.; Babaie, H. A.

2017-12-01

We have modeled a part of the complex material and process entities and properties of the volcanic system in the Volcanism Ontology (VO) applying several top-level ontologies such as Basic Formal Ontology (BFO), SWEET, and Ontology of Physics for Biology (OPB) within a single framework. The continuant concepts in BFO describe features with instances that persist as wholes through time and have qualities (attributes) that may change (e.g., state, composition, and location). In VO, the continuants include lava, volcanic rock, and volcano. The occurrent concepts in BFO include processes, their temporal boundaries, and the spatio-temporal regions within which they occur. In VO, these include eruption (process), the onset of pyroclastic flow (temporal boundary), and the space and time span of the crystallization of lava in a lava tube (spatio-temporal region). These processes can be of physical (e.g., debris flow, crystallization, injection), atmospheric (e.g., vapor emission, ash particles blocking solar radiation), hydrological (e.g., diffusion of water vapor, hot spring), thermal (e.g., cooling of lava) and other types. The properties (predicates) relate continuants to other continuants, occurrents to continuants, and occurrents to occurrents. The ontology also models other concepts such as laboratory and field procedures by volcanologists, sampling by sensors, and the type of instruments applied in monitoring volcanic activity. When deployed on the web, VO will be used to explicitly and formally annotate data and information collected by volcanologists based on domain knowledge. This will enable the integration of global volcanic data and improve the interoperability of software that deal with such data.

Diffuse CO_{2} degassing monitoring of the oceanic active volcanic island of El Hierro, Canary Islands, Spain

NASA Astrophysics Data System (ADS)

Hernández, Pedro A.; Norrie, Janice; Withoos, Yannick; García-Merino, Marta; Melián, Gladys; Padrón, Eleazar; Barrancos, José; Padilla, Germán; Rodríguez, Fátima; Pérez, Nemesio M.

2017-04-01

Even during repose periods, volcanoes release large amounts of gases from both visible (fumaroles, solfataras, plumes) and non-visible emanations (diffuse degassing). In the last 20 years, there has been considerable interest in the study of diffuse degassing as a powerful tool in volcano monitoring programs, particularly in those volcanic areas where there are no visible volcanic-hydrothermal gas emissions. Historically, soil gas and diffuse degassing surveys in volcanic environments have focused mainly on CO2 because it is, after water vapor, the most abundant gas dissolved in magma. As CO2 travels upward by advective-diffusive transport mechanisms and manifests itself at the surface, changes in its flux pattern over time provide important information for monitoring volcanic and seismic activity. Since 1998, diffuse CO2 emission has been monitored at El Hierro Island, the smallest and south westernmost island of the Canarian archipelago with an area of 278 km2. As no visible emanations occur at the surface environment of El Hierro, diffuse degassing studies have become the most useful geochemical tool to monitor the volcanic activity in this volcanic island. The island experienced a volcano-seismic unrest that began in July 2011, characterized by the location of a large number of relatively small earthquakes (M<2.5) beneath El Hierro at depths between 8 and 15 km. On October 12, 2011, a submarine eruption was confirmed during the afternoon of October 12, 2011 by visual observations off the coast of El Hierro, about 2 km south of the small village of La Restinga in the southernmost part of the island. During the pre-eruptive and eruptive periods, the time series of the diffuse CO2 emission released by the whole island experienced two significant increases. The first started almost 2 weeks before the onset of the submarine eruption, reflecting a clear geochemical anomaly in CO2 emission, most likely due to increasing release of deep seated magmatic gases to the

Volcanic eruptions on mid-ocean ridges: New evidence from the superfast spreading East Pacific Rise, 17°-19°S

NASA Astrophysics Data System (ADS)

Sinton, John; Bergmanis, Eric; Rubin, Ken; Batiza, Rodey; Gregg, Tracy K. P.; Grönvold, Karl; Macdonald, Ken C.; White, Scott M.

2002-06-01

Side-scan sonar, submersible observations and sampling of lava flows from the East Pacific Rise, 17°-19°S constrain the character and variability of submarine volcanic eruptions along mid-ocean ridges. Nine separate lava sequences were mapped using relative age and lithological contrasts among recovered samples. Axial lengths activated during eruptive episodes range from ~1 to >18 km; individual flow field areas vary from <1 to >19 km2. Estimated erupted volumes range from <1 to >200 × 106 m3. The largest unit is the chemically uniform Animal Farm lava near 18°37'S. The youngest lava is the Aldo-Kihi flow field, 17°24'-34'S, probably erupted in the early 1990s from a fissure system extending >18 km along axis. Near 18°33'S two distinct lava compositions with uniform sediment cover were recovered from lava that buries older faulted terrain. The boundary in lava composition coincides with a change in depth to the top of an axial magma lens seismic reflector, consistent with magmas from two separate reservoirs being erupted in the same event. Chemical compositions from throughout the area indicate that lavas with identical compositions can be emplaced in separate volcanic eruptions within individual segments. A comparison of our results to global data on submarine mid-ocean ridge eruptions suggests consistent dependencies of erupted volume, activated fissure lengths, and chemical heterogeneity with spreading rate, consistent with expected eruptive characteristics from ridges with contrasting thermal properties and magma reservoir depths.

Catastrophic volcanic collapse: relation to hydrothermal processes.

PubMed

López, D L; Williams, S N

1993-06-18

Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.

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

USGS Publications Warehouse

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

2011-01-01

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

Episodic Cenozoic volcanism and tectonism in the Andes of Peru

USGS Publications Warehouse

Noble, D.C.; McKee, E.H.; Farrar, E.; Petersen, U.

1974-01-01

Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tectonic and volcanic events in the Peruvian Andes during the Cenozoic includes: one or more pulses of igneous activity and intense deformation during the Paleocene and Eocene; a period of quiescence, lasting most of Oligocene time; reinception of tectonism and volcanism at the beginning of the Miocene; and a major pulse of deformation in the Middle Miocene accompanied and followed through the Pliocene by intense volcanism and plutonism. Reinception of igneous activity and tectonism at about the Oligocene-Miocene boundary, a feature recognized in other circum-Pacific regions, may reflect an increase in the rate of rotation of the Pacific plate relative to fixed or quasifixed mantle coordinates. Middle Miocene tectonism and latest Tertiary volcanism correlates with and probably is genetically related to the beginning of very rapid spreading at the East Pacific Rise. ?? 1974.

Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process

NASA Astrophysics Data System (ADS)

García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón

2014-06-01

The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

Global volcanic aerosol properties derived from emissions, 1990-2014, using CESM1(WACCM): VOLCANIC AEROSOLS DERIVED FROM EMISSIONS

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

Mills, Michael J.; Schmidt, Anja; Easter, Richard

Accurate representation of global stratospheric aerosol properties from volcanic and non-volcanic sulfur emissions is key to understanding the cooling effects and ozone-loss enhancements of recent volcanic activity. Attribution of climate and ozone variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the apparent rate of global average temperature increases, and variable recovery of the Antarctic ozone hole. We have developed a climatology of global aerosol properties from 1990 to 2014 calculated based on volcanic and non-volcanic emissions of sulfur sources. We have complied a database of volcanic SO2 emissions and plume altitudes for eruptionsmore » between 1990 and 2014, and a new prognostic capability for simulating stratospheric sulfate aerosols in version 5 of the Whole Atmosphere Community Climate Model, a component of the Community Earth System Model. Our climatology shows remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD), and with in situ measurements of aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD climatology represents a significant improvement over satellite-based analyses, which ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at mid- and high-latitudes. Our SAD climatology significantly improves on that provided for the Chemistry-Climate Model Initiative, which misses 60% of the SAD measured in situ. Our climatology of aerosol properties is publicly available on the Earth System Grid.« less

Mapping Cryo-volcanic Activity from Enceladus’ South Polar Region

NASA Astrophysics Data System (ADS)

Tigges, Mattie; Spitale, Joseph N.

2017-10-01

Using Cassini images taken of Enceladus’ south polar plumes at various times and orbital locations, we are producing maps of eruptive activity at various times. The purpose of this experiment is to understand the mechanism that controls the cryo-volcanic eruptions.The current hypothesis is that Tiger Stripe activity is modulated by tidal forcing, which would predict a correlation between orbital phase and the amount and distribution of eruptive activity. The precise nature of those correlations depends on how the crust is failing and how the plumbing system is organized.We use simulated curtains of ejected material that are superimposed over Cassini images, obtained during thirteen different flybys, taken between mid-2009 and mid-2012. Each set represents a different time and location in Enceladus’ orbit about Saturn, and contains images of the plumes from various angles. Shadows cast onto the backlit ejected material by the terminator of the moon are used to determine which fractures were active at that point in the orbit.Maps of the spatial distribution of eruptive activity at various orbital phases can be used to evaluate various hypotheses about the failure modes that produce the eruptions.

The youngest children in each school cohort are overrepresented in referrals to mental health services.

PubMed

Berg, Shipra; Berg, Erlend

2014-05-01

To investigate whether the youngest children in each school cohort are overrepresented as users of specialist mental health services. Dates of birth were obtained for all 9,157 children and adolescents referred to specialist mental health services in 3 London boroughs from 2008 to 2011. The actual frequency of referrals by month of birth is compared to the expected frequency of referrals as determined by birth statistics for the relevant age group. August-born children, who are the youngest in their cohorts in England, represent 9.38% of referrals but only 8.59% of the population in the relevant age segment. Hence, August-born children are overrepresented in referrals to specialist mental health services (P value = .007). September- and October-born children, who are the oldest in their cohorts, are underrepresented: September-born children represent 8.62% of the population but 7.99% of referrals to mental health services (P value = .032), and October-born children are 8.56% of the population but 7.86% of referrals (P value = .016). Being among the youngest in a school cohort is associated with a higher risk of referral to mental health services, while being among the oldest is a protective factor. © Copyright 2014 Physicians Postgraduate Press, Inc.

Sustained effects of volcanic ash on biofilm stoichiometry, enzyme activity and community composition in North- Patagonia streams.

PubMed

Carrillo, Uara; Díaz-Villanueva, Verónica; Modenutti, Beatriz

2018-04-15

Volcanic eruptions are extreme perturbations that affect ecosystems. These events can also produce persistent effects in the environment for several years after the eruption, with increased concentrations of suspended particles and the introduction of elements in the water column. On 4th June 2011, the Puyehue-Cordón Caulle Volcanic Complex (40.59°S-72.11°W, 2200m.a.s.l.) erupted explosively in southern Chile. The area affected by the volcano was devastated; a thick layer of volcanic ash (up to 30cm) was deposited in areas 50 km east of the volcano towards Argentina. The aim of the present study was to evaluate the effect of volcanic ash deposits on stream ecosystems four years after the eruption, comparing biofilm stoichiometry, alkaline phosphatase activity, and primary producer's assemblage in streams which were severely affected by the volcano with unaffected streams. We confirmed in the laboratory that ash deposited in the catchment of affected streams still leach phosphorus (P) into the water four years after eruption. Results indicate that affected streams still receive volcanic particles and that these particles release P, thus stream water exhibits high P concentration. Biofilm P content was higher and the C:P ratio lower in affected streams compared to unaffected streams. As a consequence of less P in unaffected streams, the alkaline phosphatase activity was higher compared to affected streams. Cyanobacteria increased their abundances (99.9% of total algal biovolume) in the affected streams suggesting that the increase in P may positively affect this group. On the contrary, unaffected streams contained a diatom dominant biofilm. In this way, local heterogeneity was created between sub-catchments located within 30 km of each other. These types of events should be seen as opportunities to gather valuable ecological information about how severe disturbances, like volcanic eruptions, shape landscapes and lotic systems for several years after the event

Temporal and Spatial Analysis of Monogenetic Volcanic Fields

NASA Astrophysics Data System (ADS)

Kiyosugi, Koji

Achieving an understanding of the nature of monogenetic volcanic fields depends on identification of the spatial and temporal patterns of volcanism in these fields, and their relationships to structures mapped in the shallow crust and inferred in the deep crust and mantle through interpretation of geochemical, radiometric and geophysical data. We investigate the spatial and temporal distributions of volcanism in the Abu Monogenetic Volcano Group, Southwest Japan. E-W elongated volcano distribution, which is identified by a nonparametric kernel method, is found to be consistent with the spatial extent of P-wave velocity anomalies in the lower crust and upper mantle, supporting the idea that the spatial density map of volcanic vents reflects the geometry of a mantle diapir. Estimated basalt supply to the lower crust is constant. This observation and the spatial distribution of volcanic vents suggest stability of magma productivity and essentially constant two-dimensional size of the source mantle diapir. We mapped conduits, dike segments, and sills in the San Rafael sub-volcanic field, Utah, where the shallowest part of a Pliocene magmatic system is exceptionally well exposed. The distribution of conduits matches the major features of dike distribution, including development of clusters and distribution of outliers. The comparison of San Rafael conduit distribution and the distributions of volcanoes in several recently active volcanic fields supports the use of statistical models, such as nonparametric kernel methods, in probabilistic hazard assessment for distributed volcanism. We developed a new recurrence rate calculation method that uses a Monte Carlo procedure to better reflect and understand the impact of uncertainties of radiometric age determinations on uncertainty of recurrence rate estimates for volcanic activity in the Abu, Yucca Mountain Region, and Izu-Tobu volcanic fields. Results suggest that the recurrence rates of volcanic fields can change by more

Constraining Silicate Weathering Processes in an Active Volcanic Complex: Implications for the Long-term Carbon Cycle

NASA Astrophysics Data System (ADS)

Washington, K.; West, A. J.; Hartmann, J.; Amann, T.; Hosono, T.; Ide, K.

2017-12-01

While analyzing geochemical archives and carbon cycle modelling can further our understanding of the role of silicate weathering as a sink in the long-term carbon cycle, it is necessary to study modern weathering processes to inform these efforts. A recent compilation of data from rivers draining basaltic catchments estimates that rock weathering in active volcanic fields (AVFs) consumes atmospheric CO2 approximately three times faster than in inactive volcanic fields (IVFs), suggesting that the eruption and subsequent weathering of large igneous provinces likely played a major role in the carbon cycle in the geologic past [1]. The study demonstrates a significant correlation between catchment mean annual temperature (MAT) and atmospheric CO2 consumption rate for IVFs. However CO2 consumption due to weathering of AVFs is not correlated with MAT as the relationship is complicated by variability in hydrothermal fluxes, reactive surface area, and groundwater flow paths. To investigate the controls on weathering processes in AVFs, we present data for dissolved and solid weathering products from Mount Aso Caldera, Japan. Aso Caldera is an ideal site for studying the how the chemistry of rivers draining an AVF is impacted by high-temperature water/rock interactions, volcanic ash weathering, and varied groundwater flow paths and residence times. Samples were collected over five field seasons from two rivers and their tributaries, cold groundwater springs, and thermal springs. These samples capture the region's temperature and precipitation seasonality. Solid samples of unaltered volcanic rocks, hydrothermally-altered materials, volcanic ash, a soil profile, and suspended and bedload river sediments were also collected. The hydrochemistry of dissolved phases were analyzed at the University of Hamburg, while the mineralogy and geochemical compositions of solid phases were analyzed at the Natural History Museum of Los Angeles. This work will be discussed in the context of

A new model for the development of the active Afar volcanic margin

NASA Astrophysics Data System (ADS)

Pik, Raphaël; Stab, Martin; Bellahsen, Nicolas; Leroy, Sylvie

2016-04-01

Volcanic passive margins, that represent more than the three quarters of continental margins worldwide, are privileged witnesses of the lithospheric extension processes thatform new oceanic basins. They are characterized by voluminous amounts of underplated, intruded and extruded magmas, under the form of massive lavas prisms (seaward-dipping reflectors, or SDR) during the course of thinning and stretching of the lithosphere, that eventually form the ocean-continent transition. The origin and mechanisms of formation of these objects are still largely debated today. We have focussed our attention in the last few years on the Afar volcanic province which represents an active analogue of such volcanic margins. We explored the structural and temporal relationships that exist between the development of the major thinning and stretching structures and the magmatic production in Central Afar. Conjugate precise fieldwork analysis along with lavas geochronology allowed us to revisit the timing and style of the rift formation, since the early syn-rift period of time in the W-Afar marginal area to present days. Extension is primarily accommodated over a wide area at the surface since the very initial periods of extension (~ 25 Ma) following the emplacement of Oligocene CFBs. We propose in our reconstruction of central Afar margin history that extension has been associated with important volumes of underplated mafic material that compensate crustal thinning. This has been facilitated by major crustal-scale detachments that help localize the thinning and underplating at depth. In line with this 'magmatic wide-rift' mode of extension, we demonstrate that episodic extension steps alternate with more protracted magmatic phases. The production of syn-rift massive flood basalts (~ 4 Ma) occurs after early thinning of both the crust and the lithosphere, which suggests that SDR formation, is controlled by previous tectonic event. We determined how the melting regime evolved in

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

USGS Publications Warehouse

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

2011-01-01

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

High-resolution 40Ar 39Ar chronology of Oligocene volcanic rocks, San Juan Mountains, Colorado

USGS Publications Warehouse

Lanphere, M.A.

1988-01-01

The central San Juan caldera complex consists of seven calderas from which eight major ash-flow tuffs were erupted during a period of intense volcanic activity that lasted for approximately 2 m.y. about 26-28 Ma. The analytical precision of conventional K-Ar dating in this time interval is not sufficient to unambiguously resolve this complex history. However, 40Ar 39Ar incremental-heating experiments provide data for a high-resolution chronology that is consistent with stratigraphie relations. Weighted-mean age-spectrum plateau ages of biotite and sanidine are the most precise with standard deviations ranging from 0.08 to 0.21 m.y. The pooled estimate of standard deviation for the plateau ages of 12 minerals is about 0.5 percent or about 125,000 to 135,000 years. Age measurements on coexisting minerals from one tuff and on two samples of each of two other tuffs indicate that a precision in the age of a tuff of better than 100,000 years can be achieved at 27 Ma. New data indicate that the San Luis caldera is the youngest caldera in the central complex, not the Creede caldera as previously thought. ?? 1988.

Development of a portable active long-path differential optical absorption spectroscopy system for volcanic gas measurements

USGS Publications Warehouse

Vita, Fabio; Kern, Christoph; Inguaggiato, Salvatore

2014-01-01

Active long-path differential optical absorption spectroscopy (LP-DOAS) has been an effective tool for measuring atmospheric trace gases for several decades. However, instruments were large, heavy and power-inefficient, making their application to remote environments extremely challenging. Recent developments in fibre-coupling telescope technology and the availability of ultraviolet light emitting diodes (UV-LEDS) have now allowed us to design and construct a lightweight, portable, low-power LP-DOAS instrument for use at remote locations and specifically for measuring degassing from active volcanic systems. The LP-DOAS was used to measure sulfur dioxide (SO2) emissions from La Fossa crater, Vulcano, Italy, where column densities of up to 1.2 × 1018 molec cm−2 (~ 500 ppmm) were detected along open paths of up to 400 m in total length. The instrument's SO2 detection limit was determined to be 2 × 1016 molec cm−2 (~ 8 ppmm), thereby making quantitative detection of even trace amounts of SO2 possible. The instrument is capable of measuring other volcanic volatile species as well. Though the spectral evaluation of the recorded data showed that chlorine monoxide (ClO) and carbon disulfide (CS2) were both below the instrument's detection limits during the experiment, the upper limits for the X / SO2 ratio (X = ClO, CS2) could be derived, and yielded 2 × 10−3 and 0.1, respectively. The robust design and versatility of the instrument make it a promising tool for monitoring of volcanic degassing and understanding processes in a range of volcanic systems.

Assessment of volcanic hazards, vulnerability, risk and uncertainty (Invited)

NASA Astrophysics Data System (ADS)

Sparks, R. S.

2009-12-01

A volcanic hazard is any phenomenon that threatens communities . These hazards include volcanic events like pyroclastic flows, explosions, ash fall and lavas, and secondary effects such as lahars and landslides. Volcanic hazards are described by the physical characteristics of the phenomena, by the assessment of the areas that they are likely to affect and by the magnitude-dependent return period of events. Volcanic hazard maps are generated by mapping past volcanic events and by modelling the hazardous processes. Both these methods have their strengths and limitations and a robust map should use both approaches in combination. Past records, studied through stratigraphy, the distribution of deposits and age dating, are typically incomplete and may be biased. Very significant volcanic hazards, such as surge clouds and volcanic blasts, are not well-preserved in the geological record for example. Models of volcanic processes are very useful to help identify hazardous areas that do not have any geological evidence. They are, however, limited by simplifications and incomplete understanding of the physics. Many practical volcanic hazards mapping tools are also very empirical. Hazards maps are typically abstracted into hazards zones maps, which are some times called threat or risk maps. Their aim is to identify areas at high levels of threat and the boundaries between zones may take account of other factors such as roads, escape routes during evacuation, infrastructure. These boundaries may change with time due to new knowledge on the hazards or changes in volcanic activity levels. Alternatively they may remain static but implications of the zones may change as volcanic activity changes. Zone maps are used for planning purposes and for management of volcanic crises. Volcanic hazards maps are depictions of the likelihood of future volcanic phenomena affecting places and people. Volcanic phenomena are naturally variable, often complex and not fully understood. There are

Slab dehydration in Cascadia and its relationship to volcanism, seismicity, and non-volcanic tremor

NASA Astrophysics Data System (ADS)

Delph, J. R.; Levander, A.; Niu, F.

2017-12-01

. Siletzia also contains most of the young arc volcanoes in the Cascades, indicating that water is retained in the slab to depths where it can feed arc volcanism. Thus, the along strike variations in volcanic activity and seismic activity in Cascadia appear to be related to variations in depth of dewatering of the downgoing oceanic lithosphere.

Contrasting styles of post-caldera volcanism along the Main Ethiopian Rift: Implications for contemporary volcanic hazards

NASA Astrophysics Data System (ADS)

Fontijn, Karen; McNamara, Keri; Zafu Tadesse, Amdemichael; Pyle, David M.; Dessalegn, Firawalin; Hutchison, William; Mather, Tamsin A.; Yirgu, Gezahegn

2018-05-01

The Main Ethiopian Rift (MER, 7-9°N) is the type example of a magma-assisted continental rift. The rift axis is populated with regularly spaced silicic caldera complexes and central stratovolcanoes, interspersed with large fields of small mafic scoria cones. The recent (latest Pleistocene to Holocene) history of volcanism in the MER is poorly known, and no eruptions have occurred in the living memory of the local population. Assessment of contemporary volcanic hazards and associated risk is primarily based on the study of the most recent eruptive products, typically those emplaced within the last 10-20 ky. We integrate new and published field observations and geochemical data on tephra deposits from the main Late Quaternary volcanic centres in the central MER to assess contemporary volcanic hazards. Most central volcanoes in the MER host large mid-Pleistocene calderas, with typical diameters of 5-15 km, and associated ignimbrites of trachyte and peralkaline rhyolite composition. In contrast, post-caldera activity at most centres comprises eruptions of peralkaline rhyolitic magmas as obsidian flows, domes and pumice cones. The frequency and magnitude of events varies between individual volcanoes. Some volcanoes have predominantly erupted obsidian lava flows in their most recent post-caldera stage (Fentale), whereas other have had up to 3 moderate-scale (VEI 3-4) explosive eruptions per millennium (Aluto). At some volcanoes we find evidence for multiple large explosive eruptions (Corbetti, Bora-Baricha, Boset-Bericha) which have deposited several centimetres to metres of pumice and ash in currently densely populated regions. This new overview has important implications when assessing the present-day volcanic hazard in this rapidly developing region. Supplementary Table 2 Main Ethiopian Rift outcrop localities with brief description of geology. All coordinates in Latitude - Longitude, WGS84 datum. Sample names (as listed in Supplementary Table 3a) follow outcrop name

New Approach for Monitoring Seismic and Volcanic Activities Using Microwave Radiometer Data

NASA Astrophysics Data System (ADS)

Maeda, Takashi; Takano, Tadashi

Interferograms formed from the data of satellite-borne synthetic aperture radar (SAR) enable us to detect slight land-surface deformations related to volcanic eruptions and earthquakes. Currently, however, we cannot determine when land-surface deformations occurred with high time resolution since the time lag between two scenes of SAR used to form interferograms is longer than the recurrent period of the satellite carrying it (several tens of days). In order to solve this problem, we are investigating new approach to monitor seismic and vol-canic activities with higher time resolution from satellite-borne sensor data, and now focusing on a satellite-borne microwave radiometer. It is less subject to clouds and rainfalls over the ground than an infrared spectrometer, so more suitable to observe an emission from land sur-faces. With this advantage, we can expect that thermal microwave energy by increasing land surface temperatures is detected before a volcanic eruption. Additionally, laboratory experi-ments recently confirmed that rocks emit microwave energy when fractured. This microwave energy may result from micro discharges in the destruction of materials, or fragment motions with charged surfaces of materials. We first extrapolated the microwave signal power gener-ated by rock failures in an earthquake from the experimental results and concluded that the microwave signals generated by rock failures near the land surface are strong enough to be detected by a satellite-borne radiometer. Accordingly, microwave energy generated by rock failures associated with a seismic activity is likely to be detected as well. However, a satellite-borne microwave radiometer has a serious problem that its spatial res-olution is too coarse compared to SAR or an infrared spectrometer. In order to raise the possibility of detection, a new methodology to compensate the coarse spatial resolution is es-sential. Therefore, we investigated and developed an analysis method to detect local

New inferences from spectral seismic energy measurement of a link between regional seismicity and volcanic activity at Mt. Etna, Italy

NASA Astrophysics Data System (ADS)

Ortiz, R.; Falsaperla, S.; Marrero, J. M.; Messina, A.

2009-04-01

The existence of a relationship between regional seismicity and changes in volcanic activity has been the subject of several studies in the last years. Generally, activity in basaltic volcanoes such as Villarica (Chile) and Tungurahua (Ecuador) shows very little changes after the occurrence of regional earthquakes. In a few cases volcanic activity has changed before the occurrence of regional earthquakes, such as observed at Teide, Tenerife, in 2004 and 2005 (Tárraga et al., 2006). In this paper we explore the possible link between regional seismicity and changes in volcanic activity at Mt. Etna in 2006 and 2007. On 24 November, 2006 at 4:37:40 GMT an earthquake of magnitude 4.7 stroke the eastern coast of Sicily. The epicenter was localized 50 km SE of the south coast of the island, and at about 160 km from the summit craters of Mt. Etna. The SSEM (Spectral Seismic Energy Measurement) of the seismic signal at stations at 1 km and 6 km from the craters highlights that four hours before this earthquake the energy associated with volcanic tremor increased, reached a maximum, and finally became steady when the earthquake occurred. Conversely, neither before nor after the earthquake, the SSEM of stations located between 80 km and 120 km from the epicentre and outside the volcano edifice showed changes. On 5 September, 2007 at 21:24:13 GMT an earthquake of magnitude 3.2 and 7.9 km depth stroke the Lipari Island, at the north of Sicily. About 38 hours before the earthquake occurrence, there was an episode of lava fountain lasting 20 hours at Etna volcano. The SSEM of the seismic signal recorded during the lava fountain at a station located at 6 km from the craters highlights changes heralding this earthquake ten hours before its occurrence using the FFM method (e.g., Voight, 1988; Ortiz et al., 2003). A change in volcanic activity - with the onset of ash emission and Strombolian explosions - was observed a couple of hours before the occurrence of the regional

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.

Barberton greenstone belt volcanism: Succession, style and petrogenesis

NASA Technical Reports Server (NTRS)

Byerly, G. R.; Lowe, D. R.

1986-01-01

The Barberton Mountain Land is an early Archean greenstone belt along the eastern margin of the Kaapvaal Craton of southern Africa. Detailed mapping in the southern portion of the belt leads to the conclusion that a substantial thickness is due to original deposition of volcanics and sediments. In the area mapped, a minimum thickness of 12km of predominantly mafic and ultramafic volcanics comprise the Komati, Hooggenoeg, and Kromberg Formations of the Onverwacht Group, and at least one km of predominantly pyroclastic and epiclastic sediments derived from dacitic volcanics comprise the Fig Tree Group. The Barberton greenstone belt formed primarily by ultramafic to mafic volcanism on a shallow marine platform which underwent little or no concurrent extension. Vents for this igneous activity were probably of the non-constructional fissure type. Dacitic volcanism occurred throughout the sequence in minor amounts. Large, constructional vent complexes were formed, and explosive eruptions widely dispersed pyroclastic debris. Only in the final stages of evolution of the belt did significant thrust-faulting occur, generally after, though perhaps overlapping with, the final stage of dacitic igneous activity. A discussion follows.

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

NASA Astrophysics Data System (ADS)

Girina, O.; Neal, Ch.

2012-04-01

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

Time variability of Io's volcanic activity from near-IR adaptive optics observations on 100 nights in 2013-2015

NASA Astrophysics Data System (ADS)

de Kleer, Katherine; de Pater, Imke

2016-12-01

Jupiter's moon Io is a dynamic target, exhibiting extreme and time-variable volcanic activity powered by tidal forcing from Jupiter. We have conducted a campaign of high-cadence observations of Io with the goal of characterizing its volcanic activity. Between Aug 2013 and the end of 2015, we imaged Io on 100 nights in the near-infrared with adaptive optics on the Keck and Gemini N telescopes, which resolve emission from individual volcanic hot spots. During our program, we made over 400 detections of 48 distinct hot spots, some of which were detected 30+ times. We use these observations to derive a timeline of global volcanic activity on Io, which exhibits wide variability from month to month. The timelines of thermal activity at individual volcanic centers have geophysical implications, and will permit future characterization by others. We evaluate hot spot detection limits and give a simple parameterization of the minimum detectable intensity as a function of emission angle, which can be applied to other analyses. We detected three outburst eruptions in August 2013, but no other outburst-scale events were observed in the subsequent ∼90 observations. Either the cluster of events in August 2013 was a rare occurrence, or there is a mechanism causing large events to occur closely-spaced in time. We also detected large eruptions (though not of outburst scale) within days of one another at Kurdalagon Patera and Sethlaus/Gabija Paterae in 2015. As was also seen in the Galileo dataset, the hot spots we detected can be separated into two categories based on their thermal emission: those that are persistently active for 1 year or more at moderate intensity, and those that are only briefly active, are time-variable, and often reach large intensities. A small number of hot spots in the latter category appear and subside in a matter of days, reaching particularly high intensities; although these are not bright enough to qualify as outbursts, their thermal signatures follow

Volcanic hazards and aviation safety

USGS Publications Warehouse

Casadevall, Thomas J.; Thompson, Theodore B.; Ewert, John W.; ,

1996-01-01

An aeronautical chart was developed to determine the relative proximity of volcanoes or ash clouds to the airports and flight corridors that may be affected by volcanic debris. The map aims to inform and increase awareness about the close spatial relationship between volcanoes and aviation operations. It shows the locations of the active volcanoes together with selected aeronautical navigation aids and great-circle routes. The map mitigates the threat that volcanic hazards pose to aircraft and improves aviation safety.

The Massive Compound Cofre de Perote Shield Volcano: a Volcanological Oddity in the Eastern Mexican Volcanic Belt

NASA Astrophysics Data System (ADS)

Siebert, L.; Carrasco-Nunez, G.; Diaz-Castellon, R.; Rodriguez, J. L.

2007-12-01

Cofre de Perote volcano anchors the northern end of the easternmost of several volcanic chains orthogonal to the E-W trend of the Mexican Volcanic Belt (MVB). Its structure, geochemistry, and volcanic history diverge significantly from that of the large dominantly andesitic stratovolcanoes that have been the major focus of research efforts in the MVB. Andesitic-trachyandesitic to dacitic-trachydacitic effusive activity has predominated at Cofre de Perote, forming a massive low-angle compound shield volcano that dwarfs the more typical smaller shield volcanoes of the central and western MVB. The 4282-m-high volcano overlooking Xalapa, the capital city of the State of Veracruz, has a diameter of about 30 km and rises more than 3000 m above the coastal plain to the east. Repeated edifice collapse has left massive horseshoe-shaped scarps that truncate the eastern side of the edifice. Five major evolutionary stages characterize the growth of this compound volcano: 1) emplacement of a multiple-vent dome complex forming the basal structure of Cofre de Perote around 1.9-1.3 Ma; 2) construction of the basal part of the compound shield volcano from at least two main upper-edifice vents at about 400 ka; 3) effusion of the summit dome-like lavas through multiple vents at ca. 240 ka; 4) eruption of a large number of geochemically diverse, alkaline and calc-alkaline Pleistocene-to-Holocene monogenetic cones (likely related to regional volcanism) through the flanks of the Cofre de Perote edifice; 5) late-stage, large-volume edifice collapse on at least two occasions (ca. 40 ka and ca. 10 ka), producing long-runout debris avalanches that traveled to the east. An undated tephra layer from Cofre de Perote overlies deposits likely of the youngest collapse. Cofre de Perote is one of several volcanoes in the roughly N-S-trending chain that has undergone major edifice collapse. As with Citlaltepetl (Pico de Orizaba) and Las Cumbres volcanoes, Cofre de Perote was constructed at the

The roar of Yasur: Handheld audio recorder monitoring of Vanuatu volcanic vent activity

NASA Astrophysics Data System (ADS)

Lorenz, Ralph D.; Turtle, Elizabeth P.; Howell, Robert; Radebaugh, Jani; Lopes, Rosaly M. C.

2016-08-01

We describe how near-field audio recording using a pocket digital sound recorder can usefully document volcanic activity, demonstrating the approach at Yasur, Vanuatu in May 2014. Prominent emissions peak at 263 Hz, interpreted as an organ-pipe mode. High-pass filtering was found to usefully discriminate volcano vent noise from wind noise, and autocorrelation of the high pass acoustic power reveals a prominent peak in exhalation intervals of 2.5, 4 and 8 s, with a number of larger explosive events at 200 s intervals. We suggest that this compact and inexpensive audio instrumentation can usefully supplement other field monitoring such as seismic or infrasound. A simple estimate of acoustic power interpreted with a dipole jet noise model yielded vent velocities too low to be compatible with pyroclast emission, suggesting difficulties with this approach at audio frequencies (perhaps due to acoustic absorption by volcanic gases).

Exploring Hawaiian Volcanism

NASA Astrophysics Data System (ADS)

Poland, Michael P.; Okubo, Paul G.; Hon, Ken

2013-02-01

In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai`i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO's founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists' understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

Neonatal Lemierre Syndrome: Youngest Reported Case and Literature Review.

PubMed

Raggio, Blake S; Grant, Maria C; Rodriguez, Kimsey; Cripe, Patrick J

2018-03-01

A previously healthy 5-week-old female was admitted for sepsis secondary to methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. After several days of hospitalization, she experienced acute decompensation in mental status despite having received targeted antibiotic therapy. Imaging revealed left peritonsillar/parapharyngeal space abscess, left venous thrombophlebitis of the internal jugular vein, and septic emboli of the lungs and brain consistent with Lemierre syndrome. Bedside needle aspiration of the parapharyngeal abscess confirmed MRSA involvement. Unfortunately, the patient continued to deteriorate over the next several days and life support was withdrawn on hospital day 16. We present the youngest reported case of Lemierre syndrome and review the literature.

How will melting of ice affect volcanic hazards in the twenty-first century?

PubMed

Tuffen, Hugh

2010-05-28

Glaciers and ice sheets on many active volcanoes are rapidly receding. There is compelling evidence that melting of ice during the last deglaciation triggered a dramatic acceleration in volcanic activity. Will melting of ice this century, which is associated with climate change, similarly affect volcanic activity and associated hazards? This paper provides a critical overview of the evidence that current melting of ice will increase the frequency or size of hazardous volcanic eruptions. Many aspects of the link between ice recession and accelerated volcanic activity remain poorly understood. Key questions include how rapidly volcanic systems react to melting of ice, whether volcanoes are sensitive to small changes in ice thickness and how recession of ice affects the generation, storage and eruption of magma at stratovolcanoes. A greater frequency of collapse events at glaciated stratovolcanoes can be expected in the near future, and there is strong potential for positive feedbacks between melting of ice and enhanced volcanism. Nonetheless, much further research is required to remove current uncertainties about the implications of climate change for volcanic hazards in the twenty-first century.

Probabilistic constraints from existing and future radar imaging on volcanic activity on Venus

NASA Astrophysics Data System (ADS)

Lorenz, Ralph D.

2015-11-01

We explore the quantitative limits that may be placed on Venus' present-day volcanic activity by radar imaging of surface landforms. The apparent nondetection of new lava flows in the areas observed twice by Magellan suggests that there is a ~60% chance that the eruption rate is ~1 km3/yr or less, using the eruption history and area/volume flow geometry of terrestrial volcanoes (Etna, Mauna Loa and Merapi) as a guide. However, if the detection probability of an individual flow is low (e.g. ~10%) due to poor resolution or quality and unmodeled viewing geometry effects, the constraint (<10 km3/yr) is not useful. Imaging at Magellan resolution or better of only ~10% of the surface area of Venus on a new mission (30 years after Magellan) would yield better than 99% chance of detecting a new lava flow, even if the volcanic activity is at the low end of predictions (~0.01 km3/yr) and is expressed through a single volcano with a stochastic eruption history. Closer re-examination of Magellan data may be worthwhile, both to search for new features, and to establish formal (location-dependent) limits on activity against which data from future missions can be tested. While Magellan-future and future-future comparisons should offer much lower detection thresholds for erupted volumes, a probabilistic approach will be required to properly understand the implications.

Geology, geochemistry, geochronology, and economic potential of Neogene volcanic rocks in the Laguna Pedernal and Salar de Aguas Calientes segments of the Archibarca lineament, northwest Argentina

NASA Astrophysics Data System (ADS)

Richards, J. P.; Jourdan, F.; Creaser, R. A.; Maldonado, G.; DuFrane, S. A.

2013-05-01

This study presents new geochemical, geochronological, isotopic, and mineralogical data, combined with new geological mapping for a 2400 km2 area of Neogene volcanic rocks in northwestern Argentina near the border with Chile, between 25°10‧S and 25°45‧S. The area covers the zone of intersection between the main axis of the Cordillera Occidental and a set of NW-SE-trending structures that form part of the transverse Archibarca lineament. This lineament has localized major ore deposits in Chile (e.g., the late Eocene La Escondida porphyry Cu deposit) and large volcanic centers such as the active Llullaillaco and Lastarría volcanoes on the border between Chile and Argentina, and the Neogene Archibarca, Antofalla, and Cerro Galán volcanoes in Argentina. Neogene volcanic rocks in the Laguna Pedernal and Salar de Aguas Calientes areas are mostly high-K calc-alkaline in composition, and range from basaltic andesites, through andesites and dacites, to rhyolites. Magmatic temperatures and oxidation states, estimated from mineral compositions, range from ~ 1000 °C and ∆FMQ ≈ 1.0-1.5 in andesites, to ~ 850 °C and ∆FMQ ≈ 1.5-2.0 in dacites and rhyolites. The oldest rocks consist of early-middle Miocene andesite-dacite plagioclase-pyroxene-phyric lava flows and ignimbrites, with 40Ar/39Ar ages ranging from 17.14 ± 0.10 Ma to 11.76 ± 0.27 Ma. Their major and trace element compositions are typical of the Andean Central Volcanic Zone, and show strong crustal contamination trends for highly incompatible elements such as Cs, Rb, Th, and U. These rocks are geochemically grouped as sub-suite 1. This widespread intermediate composition volcanism was followed in the middle-late Miocene by a period of more focused rhyodacitic flow-dome complex formation. These felsic rocks are characterized by less extreme enrichments in highly incompatible elements, and increasing depletion of heavy rare earth elements. These rocks are geochemically grouped as sub-suite 2. The

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

NASA Astrophysics Data System (ADS)

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

2012-12-01

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

Volcanic hazards at Mount Shasta, California

USGS Publications Warehouse

Crandell, Dwight R.; Nichols, Donald R.

1989-01-01

The eruptions of Mount St. Helens, Washington, in 1980 served as a reminder that long-dormant volcanoes can come to life again. Those eruptions, and their effects on people and property, also showed the value of having information about volcanic hazards well in advance of possible volcanic activity. This pamphlet about Mount Shasta provides such information for the public, even though the next eruption may still be far in the future.

Volcanic Supersites as cross-disciplinary laboratories

NASA Astrophysics Data System (ADS)

Provenzale, Antonello; Beierkuhnlein, Carl; Giamberini, Mariasilvia; Pennisi, Maddalena; Puglisi, Giuseppe

2017-04-01

Volcanic Supersites, defined in the frame of the GEO-GSNL Initiative, are usually considered mainly for their geohazard and geological characteristics. However, volcanoes are extremely challenging areas from many other points of view, including environmental and climatic properties, ecosystems, hydrology, soil properties and biogeochemical cycling. Possibly, volcanoes are closer to early Earth conditions than most other types of environment. During FP7, EC effectively fostered the implementation of the European volcano Supersites (Mt. Etna, Campi Flegrei/Vesuvius and Iceland) through the MED-SUV and FUTUREVOLC projects. Currently, the large H2020 project ECOPOTENTIAL (2015-2019, 47 partners, http://www.ecopotential-project.eu/) contributes to GEO/GEOSS and to the GEO ECO Initiative, and it is devoted to making best use of remote sensing and in situ data to improve future ecosystem benefits, focusing on a network of Protected Areas of international relevance. In ECOPOTENTIAL, remote sensing and in situ data are collected, processed and used for a better understanding of the ecosystem dynamics, analysing and modelling the effects of global changes on ecosystem functions and services, over an array of different ecosystem types, including mountain, marine, coastal, arid and semi-arid ecosystems, and also areas of volcanic origin such as the Canary and La Reunion Islands. Here, we propose to extend the network of the ECOPOTENTIAL project to include active Volcanic Supersites, such as Mount Etna and other volcanic Protected Areas, and we discuss how they can be included in the framework of the ECOPOTENTIAL workflow. A coordinated and cross-disciplinary set of studies at these sites should include geological, biological, ecological, biogeochemical, climatic and biogeographical aspects, as well as their relationship with the antropogenic impact on the environment, and aim at the global analysis of the volcanic Earth Critical Zone - namely, the upper layer of the Earth

Numeric and Relative Luminescence Dating of Volcanic Eruptions in the West Eifel Volcanic Field, Germany

NASA Astrophysics Data System (ADS)

Schmidt, C.; Schaarschmidt, M.; Kolb, T.; Richter, D.; Zöller, L.

2016-12-01

Accurate and precise dating of Holocene and Late Pleistocene volcanic eruptions is important for hazard analysis but still poses a major challenge using existing methods such as the 40Ar/39Ar or 14C techniques. Although luminescence methods are principally suitable for dating the last heating event of quartz and feldspar, working with volcanogenic materials (e.g., basalt or basanite) encounters methodological difficulties, of which anomalous fading is the most serious one. Here, we report on luminescence ages of quartz and polymineral fine grains extracted from volcanically heated native rock in contact with lava and from xenoliths embedded in basanitic scoria from the West Eifel Volcanic Field (WEVF). Combined luminescence methods (red thermoluminescence, optically stimulated and post-infrared infrared stimulated luminescence) provide significantly refined age estimates for the two investigated eruption sites, compared to independent age control. While the last volcanic activity at the Wartgesberg cinder cones took place 33.6 ± 0.4 ka ago, the Facher Höhe scoria cone is substantially younger than previously assumed (15.5 ± 0.5 ka) and represents a formerly undetected phase of young volcanism. Although not appropriate for numeric dating, the luminescence sensitivity of basalt appears to increase with eruptional age. This observation could be employed as a tool to establish a relative eruption chronology of a particular volcanic area. The WEVF, featuring a comparatively homogenous MgO-rich lava composition with many dated eruptions, represents a favorable natural laboratory to test this approach. First results of this attempt to complete the Eifel volcanic record and to chronologically assess previously undated eruptions will be presented in this contribution.

Magma genesis of the acidic volcanism in the intra-arc rift zone of the Izu volcanic arc, Japan

NASA Astrophysics Data System (ADS)

Haraguchi, S.; Tokuyama, H.; Ishii, T.

2010-12-01

The Izu volcanic arc extends over 550 km from the Izu Peninsula, Japan, to the Nishinoshima Trough or Sofugan tectonic line. It is the northernmost segment of the Izu-Bonin-Mariana arc system, which is located at the eastern side of the Philippine Sea Plate. The recent magmatism of the Izu arc is bimodal and characterized by basalt and rhyolite (e.g. Tamura and Tatsumi 2002). In the southern Izu arc, volcanic front from the Aogashima to the Torishima islands is characterized by submarine calderas and acidic volcanisms. The intra-arc rifting, characterized by back-arc depressions, small volcanic knolls and ridges, is active in this region. Volcanic rocks were obtained in 1995 during a research cruise of the R/V MOANA WAVE (Hawaii University, cruise MW9507). Geochemical variation of volcanic rocks and magma genesis was studied by Hochstaedter et al. (2000, 2001), Machida et al (2008), etc. These studies focused magma and mantle dynamics of basaltic volcanism in the wedge mantle. Acidic volcanic rocks were also dredged during the curies MW9507. However, studies of these acidic volcanics were rare. Herein, we present petrographical and chemical analyses of these acidic rocks, and compare these results with those of other acidic rocks in the Izu arc and lab experiments, and propose a model of magma genesis in a context of acidic volcanism. Dredge sites by the cruise MW9507 are 120, and about 50 sites are in the rift zone. Recovered rocks are dominated by the bimodal assemblage of basalt-basaltic andesite and dacite-rhyolite. The most abundant phase is olivine basalt, less than 50 wt% SiO2. Andesites are minor in volume and compositional gap from 56 to 65 wt% SiO2 exists. The across-arc variation of the HFSE contents and ratios, such as Zr/Y and Nb/Zr of rhyolites exhibit depleted in the volcanic front side and enriched in reararc side. This characteristic is similar to basaltic volcanism pointed out by Hochstaedter et al (2000). The petrographical features of rhyolites

Impact of volcanic ash on anammox communities in deep sea sediments.

PubMed

Song, Bongkeun; Buckner, Caroline T; Hembury, Deborah J; Mills, Rachel A; Palmer, Martin R

2014-04-01

Subaerial explosive volcanism contributes substantial amounts of material to the oceans, but little is known about the impact of volcanic ash on sedimentary microbial activity. We have studied anammox communities in deep sea sediments near the volcanically active island of Montserrat, Lesser Antilles. The rates of anammox and denitrification in the sediments were measured using (15)N isotope pairing incubation experiments, while 16S rRNA genes were used to examine anammox community structures. The higher anammox rates were measured in sediment containing the lower accumulation of volcanic ash in the surface sediments, while the lowest activities were found in sediments with the highest ash deposit. 16S rRNA gene analysis revealed the presence of 'Candidatus Scalindua spp.' in the sediments. The lowest diversity of anammox bacteria was observed in the sediments with the highest ash deposit. Overall, this study demonstrates that the deposition of volcanic material in deep sea sediments has negative impacts on activity and diversity of the anammox community. Since anammox may account for up to 79% of N2 production in marine ecosystems, periods of extensive explosive volcanism in Earth history may have had a hitherto unrecognized negative impact on the sedimentary nitrogen removal processes. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Exploring Hawaiian volcanism

USGS Publications Warehouse

Poland, Michael P.; Okubo, Paul G.; Hon, Ken

2013-01-01

In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai‘i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO’s founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists’ understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

Field-trip guide to a volcanic transect of the Pacific Northwest

USGS Publications Warehouse

Geist, Dennis; Wolff, John; Harpp, Karen

2017-08-01

The Pacific Northwest region of the United States provides world-class and historically important examples of a wide variety of volcanic features. This guide is designed to give a broad overview of the region’s diverse volcanism rather than focusing on the results of detailed studies; the reader should consult the reference list for more detailed information on each of the sites, and we have done our best to recognize previous field trip leaders who have written the pioneering guides. This trip derives from one offered as a component of the joint University of Idaho- Washington State University volcanology class taught from 1995 through 2014, and it borrows in theme from the classic field guide of Johnston and Donnelly-Nolan (1981). For readers interested in using this field guide as an educational tool, we have included an appendix with supplemental references to resources that provide useful background information on relevant topics, as well as a few suggestions for field-based exercises that could be useful when bringing students to these locations in the future. The 4-day trip begins with an examination of lava flow structures of the Columbia River Basalt, enormous lava fields that were emplaced during one of the largest eruptive episodes in Earth’s recent history. On the second day, the trip turns to the High Lava Plains, a bimodal volcanic province that transgressed from southeast to northwest from the Miocene through the Holocene, at the northern margin of the Basin and Range Province. This volcanic field provides excellent examples of welded ignimbrite, silicic lavas and domes, monogenetic basaltic lava fields, and hydrovolcanic features. The third day is devoted to a circumnavigation of Crater Lake, the result of one of the world’s best-documented caldera-forming eruptions. The caldera walls also expose the anatomy of Mount Mazama, a stratovolcano of the Cascade Range. The last day is spent at Newberry Volcano, a back-arc shield volcano topped by a

Volcanism and erosion during the past 930 k.y. at the Tatara-San Pedro complex, Chilean Andes

USGS Publications Warehouse

Singer, B.S.; Thompson, R.A.; Dungan, M.A.; Feeley, T.C.; Nelson, S.T.; Pickens, J.C.; Brown, L.L.; Wulff, A.W.; Davidson, J.P.; Metzger, J.

1997-01-01

Geologic mapping, together with 73 new K-Ar and 40Ar/39Ar age determinations of 45 samples from 17 different volcanic units, plus paleomagnetic orientations, geochemical compositions, and terrestrial photogrammetry are used to define the chronostratigraphy of the Tatara-San Pedro complex, an eruptive center at 36??S on the volcanic front of the Andean southern volcanic zone. The Tatara-San Pedro complex preserves ???55 km3 of lavas that erupted from at least three central vent regions. Remnant, unconformity-bound sequences of lavas are separated by lacunae that include significant periods of erosion. Quaternary volcanism commenced ca. 930 ka with eruption of voluminous dacitic magma, followed 100 k.y. later by the only major rhyolitic eruption. From 780 ka onward, more than 80% of the preserved volume is basaltic andesite (52%-57% SiO2), but petrographically and geochemically diverse dacitic magmas (63%-69% SiO2) erupted sporadically throughout this younger, dominantly mafic phase of activity. A few basaltic lavas (49%-52% SiO2) are present, mainly in portions of the complex older than 230 ka. The number of vents, the petrologic and geochemical diversity, and the temporal distribution of mafic and silicic lavas are consistent with emplacement of many separate batches of made magma into the shallow crust beneath the Tatara-San Pedro complex over the past million years. Nearly two-thirds of the preserved volume of the Tatara-San Pedro complex comprises the two youngest volcanoes, which were active between ca. 188-83 ka and 90-19 ka. Repeated advances of mountain glaciers punctuated growth of the complex with major erosional episodes that removed much of the pre-200 ka volcanic record, particularly on the south flank of the complex. Dating the inception of a glaciation on the basis of preserved material is difficult, but the age of the oldest lava above a lacuna may be used to estimate the timing of deglaciation. On this basis, the argon ages of basal lavas of

Active Volcanic Eruptions on Io

NASA Technical Reports Server (NTRS)

1996-01-01

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

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

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

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

Volcanic Ash on Slopes of Karymsky

NASA Technical Reports Server (NTRS)

2007-01-01

A volcanic eruption can produce gases, lava, bombs of rock, volcanic ash, or any combination of these elements. Of the volcanic products that linger on the land, most of us think of hardened lava flows, but volcanic ash can also persist on the landscape. One example of that persistence appeared on Siberia's Kamchatka Peninsula in spring 2007. On March 25, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the area around the Karymsky Volcano. In this image, volcanic ash from earlier eruptions has settled onto the snowy landscape, leaving dark gray swaths. The ash stains are confined to the south of the volcano's summit, one large stain fanning out toward the southwest, and another toward the east. At first glance, the ash stain toward the east appears to form a semicircle north of the volcano and sweep back east. Only part of this dark shape, however, is actually volcanic ash. Near the coast, the darker color may result from thicker vegetation. Similar darker coloring appears to the south. Volcanic ash is not really ash at all, but tiny, jagged bits of rock and glass. These jagged particles pose serious health risks to humans and animals who might inhale them. Likewise, the ash poses hazards to animals eating plants that have been coated with ash. Because wind can carry volcanic ash thousands of kilometers, it poses a more far-reaching hazard than other volcanic ejecta. Substantial amounts of ash can even affect climate by blocking sunlight. Karymsky is a stratovolcano composed of alternating layers of solidified ash, hardened lava, and volcanic rocks. It is one of many active volcanoes on Russia's Kamchatka Peninsula, which is part of the 'Ring of Fire' around the Pacific Rim. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

Gravity monitoring of Tatun Volcanic Group activities and inference for underground fluid circulations

NASA Astrophysics Data System (ADS)

Mouyen, Maxime; Chao, Benjamin Fong; Hwang, Cheinway; Hsieh, Wen-Chi

2016-12-01

The Tatun Volcano Group (TVG), located on the northern coast of Taiwan adjacent to the city of Taipei, experiences active hydrothermalism but has no historical record of volcanic eruption. Yet recent studies suggest that TVG is dormant-active rather than extinct. To monitor mass transfers and to gain further understanding of this volcanic area, gravity variations have been recorded continuously since 2012 using a superconducting gravimeter, and once every few months since 2005 using absolute gravimeters. We analyze the continuous gravity time series and propose a model that best explains the gravity variations due to local groundwater redistribution. By correcting these variations, we identify gravity changes as large as 35 μGal that occurred concomitantly to fluid pressure-induced earthquakes and changes in the gas composition at Dayoukeng, one of TVG's fumaroles, over 2005-2007. We examine several fluid movements that can match the gravity observations, yet too few additional constraints exist to favor any of them. In particular, no significant ground displacements are observed when these gravity variations occurred. On the other hand, the model of gravity changes due to local groundwater redistribution can be routinely computed and removed from the ongoing time gravity measurements in order to quickly identify any unusual mass transfer occurring beneath TVG.

Gravity monitoring of Tatun Volcanic Group activities and inference for underground fluid circulations

NASA Astrophysics Data System (ADS)

Mouyen, Maxime; Chao, Benjamin; Hwang, Cheinway; Hsieh, Wen-Chi

2017-04-01

The Tatun Volcano Group (TVG), located on the northern coast of Taiwan adjacent to the city of Taipei, experiences active hydrothermalism but has no historical record of volcanic eruption. Yet recent studies suggest that TVG is dormant-active rather than extinct. To monitor mass transfers and to gain further understanding of this volcanic area, gravity variations have been recorded continuously since 2012 using a superconducting gravimeter, and once every few months since 2005 using absolute gravimeters. We analyze the continuous gravity time series and propose a model that best explain the gravity variations due to local groundwater redistribution. By correcting these variations, we identify gravity changes as large as 35 µGal that occurred concomitantly to fluid pressure-induced earthquakes and changes in the gas composition at Dayoukeng, one of TVG's fumaroles, over 2005-2007. We examine several fluid movements that can match the gravity observations, yet too few additional constraints exist to favor any of them. In particular, no significant ground displacements are observed when these gravity variations occurred. On the other hand, the model of gravity changes due to local groundwater redistribution can be routinely computed and removed from the ongoing time gravity measurements in order to quickly identify any unusual mass transfer occurring beneath TVG.

Late Holocene volcanism at Medicine Lake Volcano, northern California Cascades

USGS Publications Warehouse

Donnelly-Nolan, Julie M.; Champion, Duane E.; Grove, Timothy L.

2016-05-23

Late Holocene volcanism at Medicine Lake volcano in the southern Cascades arc exhibited widespread and compositionally diverse magmatism ranging from basalt to rhyolite. Nine well-characterized eruptions have taken place at this very large rear-arc volcano since 5,200 years ago, an eruptive frequency greater than nearly all other Cascade volcanoes. The lavas are widely distributed, scattered over an area of ~300 km2 across the >2,000-km2 volcano. The eruptions are radiocarbon dated and the ages are also constrained by paleomagnetic data that provide strong evidence that the volcanic activity occurred in three distinct episodes at ~1 ka, ~3 ka, and ~5 ka. The ~1-ka final episode produced a variety of compositions including west- and north-flank mafic flows interspersed in time with fissure rhyolites erupted tangential to the volcano’s central caldera, including the youngest and most spectacular lava flow at the volcano, the ~950-yr-old compositionally zoned Glass Mountain flow. At ~3 ka, a north-flank basalt eruption was followed by an andesite eruption 27 km farther south that contains quenched basalt inclusions. The ~5-ka episode produced two caldera-focused dacitic eruptions. Quenched magmatic inclusions record evidence of intrusions that did not independently reach the surface. The inclusions are present in five andesitic, dacitic, and rhyolitic host lavas, and were erupted in each of the three episodes. Compositional and mineralogic evidence from mafic lavas and inclusions indicate that both tholeiitic (dry) and calcalkaline (wet) parental magmas were present. Petrologic evidence records the operation of complex, multi-stage processes including fractional crystallization, crustal assimilation, and magma mixing. Experimental evidence suggests that magmas were stored at 3 to 6 km depth prior to eruption, and that both wet and dry parental magmas were involved in generating the more silicic magmas. The broad distribution of eruptive events and the relative

Geochemical Interpretation of Collision Volcanism

NASA Astrophysics Data System (ADS)

Pearce, Julian

2014-05-01

Collision volcanism can be defined as volcanism that takes place during an orogeny from the moment that continental subduction starts to the end of orogenic collapse. Its importance in the Geological Record is greatly underestimated as collision volcanics are easily misinterpreted as being of volcanic arc, extensional or mantle plume origin. There are many types of collision volcanic province: continent-island arc collision (e.g. Banda arc); continent-active margin collision (e.g. Tibet, Turkey-Iran); continent-rear-arc collision (e.g. Bolivia); continent-continent collision (e.g. Tuscany); and island arc-island arc collision (e.g. Taiwan). Superimposed on this variability is the fact that every orogeny is different in detail. Nonetheless, there is a general theme of cyclicity on different time scales. This starts with syn-collision volcanism resulting from the subduction of an ocean-continent transition and continental lithosphere, and continues through post-collision volcanism. The latter can be subdivided into orogenic volcanism, which is related to thickened crust, and post-orogenic, which is related to orogenic collapse. Typically, but not always, collision volcanism is preceded by normal arc volcanism and followed by normal intraplate volcanism. Identification and interpretation of collision volcanism in the Geologic Record is greatly facilitated if a dated stratigraphic sequence is present so that the petrogenic evolution can be traced. In any case, the basis of fingerprinting collision terranes is to use geochemical proxies for mantle and subduction fluxes, slab temperatures, and depths and degrees of melting. For example, syn-collision volcanism is characterized by a high subduction flux relative to mantle flux because of the high input flux of fusible sediment and crust coupled with limited mantle flow, and because of high slab temperatures resulting from the decrease in subduction rate. The resulting geochemical patterns are similar regardless of

Acute health effects associated with exposure to volcanic air pollution (vog) from increased activity at Kilauea Volcano in 2008.

PubMed

Longo, Bernadette M; Yang, Wei; Green, Joshua B; Crosby, Frederick L; Crosby, Vickie L

2010-01-01

In 2008, the Kilauea Volcano on the island of Hawai'i increased eruption activity and emissions of sulfurous volcanic air pollution called vog. The purpose of this study was to promptly assess for a relative increase in cases of medically diagnosed acute illnesses in an exposed Hawaiian community. Using a within-clinic retrospective cohort design, comparisons were made for visits of acute illnesses during the 14 wk prior to the increased volcanic emissions (low exposure) to 14 wk of high vog exposure when ambient sulfur dioxide was threefold higher and averaged 75 parts per billion volume per day. Logistic regression analysis estimated effect measures between the low- and high-exposure cohorts for age, gender, race, and smoking status. There were statistically significant positive associations between high vog exposure and visits for medically diagnosed cough, headache, acute pharyngitis, and acute airway problems. More than a sixfold increase in odds was estimated for visits with acute airway problems, primarily experienced by young Pacific Islanders. These findings suggest that the elevated volcanic emissions in 2008 were associated with increased morbidity of acute illnesses in age and racial subgroups of the general Hawaiian population. Continued investigation is crucial to fully assess the health impact of this natural source of sulfurous air pollution. Culturally appropriate primary- and secondary-level health prevention initiatives are recommended for populations in Hawai'i and volcanically active areas worldwide.

GPS Signal Feature Analysis to Detect Volcanic Plume on Mount Etna

NASA Astrophysics Data System (ADS)

Cannavo', Flavio; Aranzulla, Massimo; Scollo, Simona; Puglisi, Giuseppe; Imme', Giuseppina

2014-05-01

Volcanic ash produced during explosive eruptions can cause disruptions to aviation operations and to population living around active volcanoes. Thus, detection of volcanic plume becomes a crucial issue to reduce troubles connected to its presence. Nowadays, the volcanic plume detection is carried out by using different approaches such as satellites, radars and lidars. Recently, the capability of GPS to retrieve volcanic plumes has been also investigated and some tests applied to explosive activity of Etna have demonstrated that also the GPS may give useful information. In this work, we use the permanent and continuous GPS network of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo (Italy) that consists of 35 stations located all around volcano flanks. Data are processed by the GAMIT package developed by Massachusetts Institute of Technology. Here we investigate the possibility to quantify the volcanic plume through the GPS signal features and to estimate its spatial distribution by means of a tomographic inversion algorithm. The method is tested on volcanic plumes produced during the lava fountain of 4-5 September 2007, already used to confirm if weak explosive activity may or may not affect the GPS signals.

Precambrian Lunar Volcanic Protolife

PubMed Central

Green, Jack

2009-01-01

Five representative terrestrial analogs of lunar craters are detailed relevant to Precambrian fumarolic activity. Fumarolic fluids contain the ingredients for protolife. Energy sources to derive formaldehyde, amino acids and related compounds could be by flow charging, charge separation and volcanic shock. With no photodecomposition in shadow, most fumarolic fluids at 40 K would persist over geologically long time periods. Relatively abundant tungsten would permit creation of critical enzymes, Fischer-Tropsch reactions could form polycyclic aromatic hydrocarbons and soluble volcanic polyphosphates would enable assembly of nucleic acids. Fumarolic stimuli factors are described. Orbital and lander sensors specific to protolife exploration including combined Raman/laser-induced breakdown spectrocsopy are evaluated. PMID:19582224

Tephra layers from Holocene lake sediments of the Sulmona Basin, central Italy: implications for volcanic activity in Peninsular Italy and tephrostratigraphy in the central Mediterranean area

NASA Astrophysics Data System (ADS)

Giaccio, B.; Messina, P.; Sposato, A.; Voltaggio, M.; Zanchetta, G.; Galadini, F.; Gori, S.; Santacroce, R.

2009-12-01

We present a new tephrostratigraphic record from the Holocene lake sediments of the Sulmona basin, central Italy. The Holocene succession is represented by whitish calcareous mud that is divided into two units, SUL2 (ca 32 m thick) and SUL1 (ca 8 m thick), for a total thickness of ca 40 m. These units correspond to the youngest two out of six sedimentary cycles recognised in the Sulmona basin that are related to the lake sedimentation since the Middle Pleistocene. Height concordant U series age determinations and additional chronological data constrain the whole Holocene succession to between ca 8000 and 1000 yrs BP. This includes a sedimentary hiatus that separates the SUL2 and SUL1 units, which is roughly dated between <2800 and ca 2000 yrs BP. A total of 31 and 6 tephra layers were identified within the SUL2 and SUL1 units, respectively. However, only 28 tephra layers yielded fresh micro-pumices or glass shards suitable for chemical analyses using a microprobe wavelength dispersive spectrometer. Chronological and compositional constraints suggest that 27 ash layers probably derive from the Mt. Somma-Vesuvius Holocene volcanic activity, and one to the Ischia Island eruption of the Cannavale tephra (2920 ± 450 cal yrs BP). The 27 ash layers compatible with Mt. Somma-Vesuvius activity are clustered in three different time intervals: from ca 2000 to >1000; from 3600 to 3100; and from 7600 to 4700 yrs BP. The first, youngest cluster, comprises six layers and correlates with the intense explosive activity of Mt. Somma-Vesuvius that occurred after the prominent AD 79 Pompeii eruption, but only the near-Plinian event of AD 472 has been tentatively recognised. The intermediate cluster (3600-3100 yrs BP) starts with tephra that chemically and chronologically matches the products from the "Pomici di Avellino" eruption (ca 3800 ± 200 yrs BP). This is followed by eight further layers, where the glasses exhibit chemical features that are similar in composition to the

Evidence for sub-lacustrine volcanic activity in Lake Bolsena (central Italy) revealed by high resolution seismic data sets

NASA Astrophysics Data System (ADS)

Lindhorst, Katja; Krastel, Sebastian; Wagner, Bernd; Schuerer, Anke

2017-06-01

The Bolsena caldera that formed between 0.6 and 0.2 Ma has a well preserved structural rim, which makes it an ideal site to study the tectonic and volcanic evolution of calderas. However, the main area is covered by a 150 m deep lake which makes it rather difficult to investigate the subsurface structure directly. To overcome this problem new high resolution hydro-acoustic surveys using a multichannel reflection seismic system and a sediment echo-sounder system were conducted in September 2012. As space was limited we used a rowing boat towed by a rubber boat to handle a 36 m long and 24 channel streamer to receive seismic reflections produced using a Mini GI-Gun (0.25 l). The subsurface structure of Lake Bolsena was imaged up to a sediment depth of 190 m, which is estimated to have filled over a period of 333 kyrs. However, massive pyroclastic flow deposits found in the deeper parts of the basin indicate an initial infill of volcanic deposits from two adjacent younger calderas, the Latera (W) and Montefiascone (SE) calderas. Our data suggest that the caldera has a long history of active volcanism, because the lacustrine sediments show post-sedimentary influences of geothermal fluids. We mapped several mound structures at various stratigraphic depths. Two volcanic structures outcrop at the modern lake surface implying recent activity. One of these structures is hardly covered by sediments and has a crater-like feature in its summit. The other structure shows a pockmark-like depression on top. Another observable feature is a partially sediment filled crater located in the western part of the lake which further implies the existence of a magma chamber located beneath the Bolsena caldera. Since the late Pleistocene and Holocene, the sedimentation was mainly hemipelagic evidenced by a sediment drape of up to 10 m thick sediment drape on the uppermost sediments. Beneath the drape we found evidence for a distal tephra layer likely related to an explosive eruption from

Multiteide Project: Multiparametric characterization of the activity of Teide-Pico Viejo volcanic system

NASA Astrophysics Data System (ADS)

Domínguez Cerdeña, Itahiza; Villasante-Marcos, Victor; Meletlidis, Stavros; Sainz-Maza, Sergio; Abella, Rafael; Torres, Pedro A.; Sánchez, Nieves; Luengo-Oroz, Natividad; José Blanco, María; García-Cañada, Laura; Pereda de Pablo, Jorge; Lamolda, Héctor; Moure, David; Del Fresno, Carmen; Finizola, Anthony; Felepto, Alicia

2017-04-01

Teide-Pico Viejo complex stands for one of the major natural volcanic hazards in the Canary Islands, due to the expected types of eruptions in the area and the high number of inhabitants in Tenerife Island. Therefore, it is necessary to have a volcanic alert system able to afford a precise assessment of the current state of the complex. For this purpose, the knowledge of the expected signals at each volcanic activity level is required. Moreover, the external effects that can affect the measurements shall be distinguished, external influences as the atmosphere are qualitatively known but have not been quantified yet. The objective of the project is to collect, analyze and jointly and continuously evaluate over time geophysical, geodetic, geochemical and meteorological data from the Teide-Pico Viejo complex and its surroundings. A continuous multiparametric network have been deployed in the area, which, together with the data provided by the Volcano Monitoring Network of the Instituto Geográfico Nacional (IGN) and data from other institutions will provide a comprehensive set of data with high resolution in both space and time. This multiparametric network includes a seismic array, two self-potential lines for continuous measurements, five magnetometers and two weather stations. The network will be complemented with 8 CGPS stations, one tiltmeter, 10 seismic stations, and four thermometric stations on the fumaroles of Teide volcano that IGN already manage in Tenerife. The data will be completed with the results from different repeated surveys of self potential, soil temperature and CO2 diffuse flux in several pre-established areas on top of Teide throughout the entire duration of project. During the project, new computation tools will be developed to study the correlation between the different parameters analyzed. The results obtained will characterize the possible seasonal fluctuations of each parameter and the variations related to meteorological phenomena. In

Climatic and Chemical Effects of Punctuated Volcanism on Early Mars

NASA Astrophysics Data System (ADS)

Halevy, I.; Head, J. W.

2012-12-01

The geological record of Mars shows a pronounced peak in volcanic activity during the transition between the late Noachian and early Hesperian epochs. This peak appears coeval with profound climatic and chemical changes in the surface environment, including the formation of the majority of known valley networks, open-basin lakes and the deposition of massive sulfate-bearing deposits of aqueous origin. It has been suggested that volcanism maintained a warmer climate and an active hydrological cycle through the radiative effect of volcanically emitted greenhouse gases, such as CO2, H2O and SO2. However, previous model attempts at explaining overland flow with CO2-H2O greenhouse atmospheres required several bars of CO2, even including the warming effect of infrared scattering by CO2 ice clouds. This amount of CO2 is in apparent disagreement with recent estimates of volcanic outgassing on Mars. The net climatic effect of volcanic SO2 emissions into the atmosphere of early Mars has been the topic of recent debate, because it is unclear whether strong greenhouse warming by SO2 or strong cooling by scattering sulfate aerosols should dominate. To address this problem, we considered two previously neglected phenomena: i) the punctuated, rather than continuous, nature of volcanic eruptions, and ii) the role of preexisting dust grains and volcanic ash as condensation nuclei for sulfuric acid. For this purpose we developed a coupled model of volcanic eruption and atmospheric response, including detailed aerosol microphysics. We find that while SO2 concentrations increase rapidly and dramatically with the initiation of a strong volcanic eruption, the dynamics of sulfate aerosol formation in the martian atmosphere results in a delay of aerosol-related cooling by several months to years. Moreover, the existence of dust in the atmosphere prior to the volcanic eruption, as well as the emission and global distribution of fine volcanic ash particles, results in the formation of H2SO4

Constructing event trees for volcanic crises

USGS Publications Warehouse

Newhall, C.; Hoblitt, R.

2002-01-01

Event trees are useful frameworks for discussing probabilities of possible outcomes of volcanic unrest. Each branch of the tree leads from a necessary prior event to a more specific outcome, e.g., from an eruption to a pyroclastic flow. Where volcanic processes are poorly understood, probability estimates might be purely empirical - utilizing observations of past and current activity and an assumption that the future will mimic the past or follow a present trend. If processes are better understood, probabilities might be estimated from a theoritical model, either subjectively or by numerical simulations. Use of Bayes' theorem aids in the estimation of how fresh unrest raises (or lowers) the probabilities of eruptions. Use of event trees during volcanic crises can help volcanologists to critically review their analysis of hazard, and help officials and individuals to compare volcanic risks with more familiar risks. Trees also emphasize the inherently probabilistic nature of volcano forecasts, with multiple possible outcomes.

Compositional variation of lavas from a young volcanic field on the Southern Mid-Atlantic Ridge, 8°48'S

NASA Astrophysics Data System (ADS)

Haase, K.; Brandl, P. A.; Melchert, B.; Hauff, F.; Garbe-Schoenberg, C.; Paulick, H.; Kokfelt, T. F.; Devey, C. W.

2012-12-01

Volcanic eruptions along the mid-oceanic ridge system are the most abundant signs of volcanic activity on Earth but little is known about the timescales and nature of these processes. The main parameter determining eruption frequency as well as magma composition appears to be the spreading rate of the mid-oceanic ridge. However, few observations on the scale of single lava flows exist from the slow-spreading Mid-Atlantic Ridge so far. Here we present geological observations and geochemical data for the youngest volcanic features of the so-called A2 segment (Bruguier et al., 2003, Hoernle et al., 2011) of the slow-spreading (33 mm/yr) southern Mid-Atlantic Ridge at 8°48'S. This segment has a thickened crust of about 9 km indicating increased melt production in the mantle. Side-scan sonar mapping revealed a young volcanic field with high reflectivity that was probably erupted from two volcanic fissures each of about 3 km length. Small-scale sampling of the young lava field at 8°48'S by ROV and wax corer and geochemical analyses of the volcanic glasses reveal three different compositional lava units along this about 11 km long portion of the ridge. Based on the incompatible element compositions of volcanic glasses (e.g. K/Ti, Ce/Yb) we can distinguish two lava units forming the northern and the larger southern part of the lava field covering areas of about 5 and 9 square kilometres, respectively. Basalts surrounding the lava field and from an apparently old pillow mound within the young flows are more depleted in incompatible elements than glasses from the young volcanic field. Radium disequilibria suggest that most lavas from this volcanic field have ages of 3000 to 5000 yrs whereas the older lavas surrounding the lava field are older than 8000 yrs. Faults and a thin sediment cover on many lavas support the ages and indicate that this part of the Mid-Atlantic Ridge is in a tectonic rather than in a magmatic stage. Lavas from the northern and southern ends of the

Volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory 1993

USGS Publications Warehouse

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

1996-01-01

During 1993, the Alaska Volcano Observatory (AVO) responded to episodes of eruptive activity or false alarms at nine volcanic centers in the state of Alaska. Additionally, as part of a formal role in KVERT (the Kamchatkan Volcano Eruption Response Team), AVO staff also responded to eruptions on the Kamchatka Peninsula, details of which are summarized in Miller and Kurianov (1993). In 1993, AVO maintained seismic instrumentation networks on four volcanoes of the Cook Inlet region--Spurr, Redoubt, Iliamna, and Augustine--and two stations at Dutton Volcano near King Cove on the Alaska Peninsula. Other routine elements of AVO's volcano monitoring program in Alaska include periodic airborne measurement of volcanic SO2 and CO2 at Cook Inlet volcanoes (Doukas, 1995) and maintenance of a lightning detection system in Cook Inlet (Paskievitch and others, 1995).

ALVIN investigation of an active propagating rift system, Galapagos 95.5° W

USGS Publications Warehouse

Hey, R.N.; Sinton, J.M.; Kleinrock, M.C.; Yonover, R.N.; MacDonald, K.C.; Miller, S.P.; Searle, R.C.; Christie, D.M.; Atwater, T.M.; Sleep, Norman H.; Johnson, H. Paul; Neal, C.A.

1992-01-01

ALVIN investigations have defined the fine-scale structural and volcanic patterns produced by active rift and spreading center propagation and failure near 95.5° W on the Galapagos spreading center. Behind the initial lithospheric rifting, which is propagating nearly due west at about 50 km m.y.−1, a triangular block of preexisting lithosphere is being stretched and fractured, with some recent volcanism along curving fissures. A well-organized seafloor spreading center, an extensively faulted and fissured volcanic ridge, develops ~ 10 km (~ 200,000 years) behind the tectonic rift tip. Regional variations in the chemical compositions of the youngest lavas collected during this program contrast with those encompassing the entire 3 m.y. of propagation history for this region. A maximum in degree of magmatic differentiation occurs about 9 km behind the propagating rift tip, in a region of diffuse rifting. The propagating spreading center shows a gentle gradient in magmatic differentiation culminating at the SW-curving spreading center tip. Except for the doomed rift, which is in a constructional phase, tectonic activity also dominates over volcanic activity along the failing spreading system. In contrast to the propagating rift, failing rift lavas show a highly restricted range of compositions consistent with derivation from a declining upwelling zone accompanying rift failure. The lithosphere transferred from the Cocos to the Nazca plate by this propagator is extensively faulted and characterized by ubiquitous talus in one of the most tectonically disrupted areas of seafloor known. The pseudofault scarps, where the preexisting lithosphere was rifted apart, appear to include both normal and propagator lavas and are thus more lithologically complex than previously thought. Biological communities, probably vestimentiferan tubeworms, occur near the top of the outer pseudofault scarp, although no hydrothermal venting was observed.

Bayesian analysis of volcanic eruptions

NASA Astrophysics Data System (ADS)

Ho, Chih-Hsiang

1990-10-01

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

Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions

NASA Technical Reports Server (NTRS)

1979-01-01

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

Stratigraphy of the Caloris Basin, Mercury: Implications for Volcanic History and Basin Impact Melt

NASA Technical Reports Server (NTRS)

Ernst, Carolyn M.; Denevi, Brett W.; Barnouin, Olivier S.; Klimczak, Christian; Chabot, Nancy L.; Head, James W.; Murchie, Scott L.; Neumann, Gregory A.; Prockter, Louis M.; Robinson, Mark S.;

Volcanic Eruptions in Kamchatka

NASA Image and Video Library

2007-04-30

One of the most volcanically active regions of the world is the Kamchatka Peninsula in eastern Siberia, Russia. It is not uncommon for several volcanoes to be erupting at the same time. NASA Terra satellite acquired this image on April 26, 2007

Easy Volcanic Aerosol

NASA Astrophysics Data System (ADS)

Toohey, Matthew; Stevens, Bjorn; Schmidt, Hauke; Timmreck, Claudia

2016-04-01

Radiative forcing by stratospheric sulfate aerosol of volcanic origin is one of the strongest drivers of natural climate variability. Transient model simulations attempting to match observed climate variability, such as the CMIP historical simulations, rely on volcanic forcing reconstructions based on observations of a small sample of recent eruptions and coarse proxy data for eruptions before the satellite era. Volcanic forcing data sets used in CMIP5 were provided either in terms of optical properties, or in terms of sulfate aerosol mass, leading to significant inter-model spread in the actual volcanic radiative forcing produced by models and in their resulting climate responses. It remains therefore unclear to what degree inter-model spread in response to volcanic forcing represents model differences or variations in the forcing. In order to isolate model differences, Easy Volcanic Aerosol (EVA) provides an analytic representation of volcanic stratospheric aerosol forcing, based on available observations and aerosol model results, prescribing the aerosol's radiative properties and primary modes of spatial and temporal variability. In contrast to regriddings of observational data, EVA allows for the production of physically consistent forcing for historic and hypothetical eruptions of varying magnitude, source latitude, and season. Within CMIP6, EVA will be used to reconstruct volcanic forcing over the past 2000 years for use in the Paleo-Modeling Intercomparison Project (PMIP), and will provide forcing sets for VolMIP experiments aiming to quantify model uncertainty in the response to volcanic forcing. Here, the functional form of EVA will be introduced, along with illustrative examples including the EVA-based reconstruction of volcanic forcing over the historical period, and that of the 1815 Tambora eruption.

Role of Social Media and Networking in Volcanic Crises and Communication

NASA Astrophysics Data System (ADS)

Sennert, S.; Klemetti, E. W.; Bird, D. K.

2016-12-01

The growth of social media as a primary and often preferred news source has led to the rapid dissemination of information about volcanic eruptions and potential volcanic crises as they begin, evolve, and end. This information comes from a variety of sources: news organisations, emergency management personnel, individuals (both members of the public and official representatives), and volcano monitoring agencies. Once posted, this information is easily shared, increasing the reach to a much broader population than more traditional forms of media, such as radio and newspapers. The onset and popularity of social media as a vehicle for dissemination of eruption information points toward the need to systematically incorporate social media into the official channels that volcano observatories use to distribute activity statements, forecasts, and images. We explore two examples of projects that collect/disseminate information regarding volcanic crises and eruptive activity via social media sources; the Smithsonian/USGS Weekly Volcanic Activity Report (WVAR), which summarizes new and on-going volcanic activity globally and on a weekly basis, and Eruptions, a blog that discusses eruptions as well as other volcanic topics. Based on these experiences, recommendations are made to volcanic observatories in relation to the use of social media as a communication tool. These recommendations include: using social media as a two-way dialogue to communicate and receive information directly from the public and other sources; stating that the social media account is from an official source; and posting types of information that users want to see such as images, videos, and figures.

SHARAD Penetrates Only the Youngest Geological Units on Mars

NASA Astrophysics Data System (ADS)

Stillman, D.; Grimm, R. E.

2009-12-01

The SHAllow RADar (SHARAD) instrument on the Mars Reconnaissance Orbiter was intended to receive echoes from up to 1 km deep in the rocky martian subsurface. Such deep penetration only occurs in the icy polar caps and in certain ice-rich units. In fact, over the majority of the rocky units of Mars, only surface echoes are detected. Therefore, rocky units are more attenuating than expected. To gain insight into the cause of this attenuation, we correlated SHARAD subsurface reflectors with a geologic map of the northern plains of Mars [Tanaka et al., 2005]. Our survey was restricted to this area due to general smoother topography and hence less potential influence of surface scattering (clutter). All released SHARAD data (approximately 1,500 radargrams) overlying the geologic map were individually interpreted. Geologic units were categorized by their map description into ice-rich, pristine volcanic, and water-altered units. The last category comprises units interpreted to be fluvial, lacustrine, or periglacial in origin, as well as volcanic and other units that were subsequently altered by water or ice. Radar reflections in each unit were further categorized as abundant, occasional, or none. We found that abundant reflections are only detected in geologic units that are Amazonian in age, and ice-rich or pristine volcanic. No reflections are seen in water altered units. Occasional reflections are detected in Hesperian-aged pristine volcanic units. We propose two endmember hypotheses for this attenuation behavior, scattering and absorption, but they could act jointly. The young pristine volcanic units that SHARAD penetrates consist of thick (about 50 m) flood basalts or tuff. These units are expected to have cooling joints in them, but little if any other heterogeneity; therefore their scattering loss should be small. With increasing age and thermoelastic stress due to global cooling and contraction, these previously homogeneous volcanics could become increasingly

Matching conjugate volcanic rifted margins: 40Ar/ 39Ar chrono-stratigraphy of pre- and syn-rift bimodal flood volcanism in Ethiopia and Yemen

NASA Astrophysics Data System (ADS)

Ukstins, Ingrid A.; Renne, Paul R.; Wolfenden, Ellen; Baker, Joel; Ayalew, Dereje; Menzies, Martin

2002-05-01

40Ar/ 39Ar dating of mineral separates and whole-rock samples of rhyolitic ignimbrites and basaltic lavas from the pre- and syn-rift flood volcanic units of northern Ethiopia provides a temporal link between the Ethiopian and Yemen conjugate rifted volcanic margins. Sixteen new 40Ar/ 39Ar dates confirm that basaltic flood volcanism in Ethiopia was contemporaneous with flood volcanism on the conjugate margin in Yemen. The new data also establish that flood volcanism initiated prior to 30.9 Ma in Ethiopia and may predate initiation of similar magmatic activity in Yemen by ˜0.2-2.0 Myr. Rhyolitic volcanism in Ethiopia commenced at 30.2 Ma, contemporaneous with the first rhyolitic ignimbrite unit in Yemen at ˜30 Ma. Accurate and precise 40Ar/ 39Ar dates on initial rhyolitic ignimbrite eruptions suggest that silicic flood volcanism in Afro-Arabia post-dates the Oligocene Oi2 global cooling event, ruling out a causative link between these explosive silicic eruptions (with individual volumes ≥200 km 3) and climatic cooling which produced the first major expansion of the Antarctic ice sheets. Ethiopian volcanism shows a progressive and systematic younging from north to south along the escarpment and parallel to the rifted margin, from pre-rift flood volcanics in the north to syn-rift northern Main Ethiopian Rift volcanism in the south. A dramatic decrease in volcanic activity in Ethiopia between 25 and 20 Ma correlates with a prominent break-up unconformity in Yemen (26-19 Ma), both of which mark the transition from pre- to syn-rift volcanism (˜25-26 Ma) triggered by the separation of Africa and Arabia. The architecture of the Ethiopian margin is characterized by accumulation and preservation of syn-rift volcanism, while the Yemen margin was shaped by denudational unloading and magmatic starvation as the Arabian plate rifted away from the Afar plume. A second magmatic hiatus and angular unconformity in the northern Main Ethiopian Rift is evident at 10.6-3.2 Ma, and is

Volcanic Thunder From Explosive Eruptions at Bogoslof Volcano, Alaska

NASA Astrophysics Data System (ADS)

Haney, Matthew M.; Van Eaton, Alexa R.; Lyons, John J.; Kramer, Rebecca L.; Fee, David; Iezzi, Alexandra M.

2018-04-01

Lightning often occurs during ash-producing eruptive activity, and its detection is now being used in volcano monitoring for rapid alerts. We report on infrasonic and sonic recordings of the related, but previously undocumented, phenomenon of volcanic thunder. We observe volcanic thunder during the waning stages of two explosive eruptions at Bogoslof volcano, Alaska, on a microphone array located 60 km away. Thunder signals arrive from a different direction than coeruptive infrasound generated at the vent following an eruption on 10 June 2017, consistent with locations from lightning networks. For the 8 March 2017 eruption, arrival times and amplitudes of high-frequency thunder signals correlate well with the timing and strength of lightning detections. In both cases, the thunder is associated with lightning that continues after significant eruptive activity has ended. Infrasonic and sonic observations of volcanic thunder offer a new avenue for studying electrification processes in volcanic plumes.

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

USGS Publications Warehouse

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

2005-01-01

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

Volcanic stratigraphy: A review

NASA Astrophysics Data System (ADS)

Martí, Joan; Groppelli, Gianluca; Brum da Silveira, Antonio

2018-05-01

Volcanic stratigraphy is a fundamental component of geological mapping in volcanic areas as it yields the basic criteria and essential data for identifying the spatial and temporal relationships between volcanic products and intra/inter-eruptive processes (earth-surface, tectonic and climatic), which in turn provides greater understanding of the geological evolution of a region. Establishing precise stratigraphic relationships in volcanic successions is not only essential for understanding the past behaviour of volcanoes and for predicting how they might behave in the future, but is also critical for establishing guidelines for exploring economic and energy resources associated with volcanic systems or for reconstructing the evolution of sedimentary basins in which volcanism has played a significant role. Like classical stratigraphy, volcanic stratigraphy should also be defined using a systematic methodology that can provide an organised and comprehensive description of the temporal and spatial evolution of volcanic terrain. This review explores different methods employed in studies of volcanic stratigraphy, examines four case studies that use differing stratigraphic approaches, and recommends methods for using systematic volcanic stratigraphy based on the application of the concepts of traditional stratigraphy but adapted to the needs of volcanological environment.

Distinguishing high surf from volcanic long-period earthquakes

USGS Publications Warehouse

Lyons, John; Haney, Matt; Fee, David; Paskievitch, John F.

2014-01-01

Repeating long-period (LP) earthquakes are observed at active volcanoes worldwide and are typically attributed to unsteady pressure fluctuations associated with fluid migration through the volcanic plumbing system. Nonvolcanic sources of LP signals include ice movement and glacial outburst floods, and the waveform characteristics and frequency content of these events often make them difficult to distinguish from volcanic LP events. We analyze seismic and infrasound data from an LP swarm recorded at Pagan volcano on 12–14 October 2013 and compare the results to ocean wave data from a nearby buoy. We demonstrate that although the events show strong similarity to volcanic LP signals, the events are not volcanic but due to intense surf generated by a passing typhoon. Seismo-acoustic methods allow for rapid distinction of volcanic LP signals from those generated by large surf and other sources, a critical task for volcano monitoring.

Lahar—River of volcanic mud and debris

USGS Publications Warehouse

Major, Jon J.; Pierson, Thomas C.; Vallance, James W.

2018-05-09

Lahar, an Indonesian word for volcanic mudflow, is a mixture of water, mud, and volcanic rock flowing swiftly along a channel draining a volcano. Lahars can form during or after eruptions, or even during periods of inactivity. They are among the greatest threats volcanoes pose to people and property. Lahars can occur with little to no warning, and may travel great distances at high speeds, destroying or burying everything in their paths.Lahars form in many ways. They commonly occur when eruptions melt snow and ice on snow-clad volcanoes; when rains fall on steep slopes covered with fresh volcanic ash; when crater lakes, volcano glaciers or lakes dammed by volcanic debris suddenly release water; and when volcanic landslides evolve into flowing debris. Lahars are especially likely to occur at erupting or recently active volcanoes.Because lahars are so hazardous, U.S. Geological Survey scientists pay them close attention. They study lahar deposits and limits of inundation, model flow behavior, develop lahar-hazard maps, and work with community leaders and governmental authorities to help them understand and minimize the risks of devastating lahars.

Volcanism and associated hazards: the Andean perspective

NASA Astrophysics Data System (ADS)

Tilling, R. I.

2009-12-01

Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (<0.05 km3) in 1985 of Nevado del Ruiz (Colombia) killed about 25 000 people - the worst volcanic disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and

Volcanism and associated hazards: The Andean perspective

USGS Publications Warehouse

Tilling, R.I.

2009-01-01

Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene.

The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (<0.05 km 3) in 1985 of Nevado del Ruiz (Colombia) killed about 25 000 people - the worst volcanic disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia

Middle Pleistocene volcanic activity dated by red thermoluminescence (RTL) - a case study from Lanzarote (Canary Islands)

NASA Astrophysics Data System (ADS)

von Suchodoletz, H.; Blanchard, H.; Rittner, S.; Radtke, U.; Fuchs, M.; Dietze, M.; Zöller, L.

2009-04-01

On Lanzarote (Canary Islands) soils were baked by Quaternary lava flows. This offers the possibility to date phases of eruptive activity by red thermoluminescence (RTL). We dated soil material baked by two different lava flows originating from the "Las Calderetas de Guatiza" volcanic chain in the northeast of the island by RTL. Furthermore, three samples of Helicidae-mollusk shells overlying one of the lava flows (site Mála) were dated using electron spin resonance (ESR). RTL datings were carried out using quartz grains 63-200 µm from baked material that were originally brought by eolian transport from the nearby Saharan desert. It appears that in spite of a baking temperature < 550°C the RTL-signal was sufficiently annealed and thus dating by RTL was possible. RTL ages of ca. 170 ka show good agreement with each other, however, ESR ages are up to 40 % higher than the corresponding RTL age of the lava flow in Mála. Despite this disagreement these results demonstrate that eruptive activity of the volcanic chain occurred during the Middle Pleistocene rather than during the Early Holocene/Late Pleistocene as supposed based on geomorphologic features. Furthermore, they show that 14C-ages of mollusk shells originating from Mála are underestimating volcanic activity up to a factor of 10, a problem often recorded in arid areas. These results demonstrate the value of luminescence and ESR datings on the semi arid Eastern Canary Islands. The successful dating of lava-baked soils on Lanzarote by RTL thus offers the possibility to further investigate the yet fragmentary Middle and Late Quaternary eruptive history of these islands.

The Origin of Widespread Long-lived Volcanism Across the Galapagos Volcanic Province

NASA Astrophysics Data System (ADS)

O'Connor, J. M.; Stoffers, P.; Wijbrans, J. R.; Worthington, T. J.

2005-12-01

40Ar/39Ar ages for rocks dredged (SO144 PAGANINI expedition) and drilled (DSDP) from the Galapagos Volcanic Province (Cocos, Carnegie, Coiba and Malpelo aseismic ridges and associated seamounts) show evidence of 1) increasing age with distance from the Galapagos Archipelago, 2) long-lived episodic volcanism at many locations, and 3) broad overlapping regions of coeval volcanism. The widespread nature of synchronous volcanism across the Galapagos Volcanic Province (GVP) suggests a correspondingly large Galapagos hotspot melting anomaly (O'Connor et al., 2004). Development of the GVP via Cocos and Nazca plate migration and divergence over this broad melting anomaly would explain continued multiple phases of volcanism over millions of years following the initial onset of hotspot volcanism. The question arising from these observations is whether long-lived GVP episodic volcanism is equivalent to `rejuvenescent' or a `post-erosional' phase of volcanism that occurs hundreds of thousands or million years after the main shield-building phase documented on many mid-plate seamount chains, most notably along the Hawaiian-Emperor Seamount Chain? Thus, investigating the process responsible for long-lived episodic GVP volcanism provides the opportunity to evaluate this little understood process of rejuvenation in a physical setting very different to the Hawaiian-Emperor Chain (i.e. on/near spreading axis versus mid-plate). We consider here timing and geochemical information to test the various geodynamic models proposed to explain the origin of GVP hotspot volcanism, especially the possibility of rejuvenated phases that erupt long after initial shield-building.

Airborne volcanic ash; a global threat to aviation

USGS Publications Warehouse

Neal, Christina A.; Guffanti, Marianne C.

2010-01-01

The world's busy air traffic corridors pass over or downwind of hundreds of volcanoes capable of hazardous explosive eruptions. The risk to aviation from volcanic activity is significant - in the United States alone, aircraft carry about 300,000 passengers and hundreds of millions of dollars of cargo near active volcanoes each day. Costly disruption of flight operations in Europe and North America in 2010 in the wake of a moderate-size eruption in Iceland clearly demonstrates how eruptions can have global impacts on the aviation industry. Airborne volcanic ash can be a serious hazard to aviation even hundreds of miles from an eruption. Encounters with high-concentration ash clouds can diminish visibility, damage flight control systems, and cause jet engines to fail. Encounters with low-concentration clouds of volcanic ash and aerosols can accelerate wear on engine and aircraft components, resulting in premature replacement. The U.S. Geological Survey (USGS), in cooperation with national and international partners, is playing a leading role in the international effort to reduce the risk posed to aircraft by volcanic eruptions.

Miocene volcanism in the Oaş-Gutâi Volcanic Zone, Eastern Carpathians, Romania: Relationship to geodynamic processes in the Transcarpathian Basin

NASA Astrophysics Data System (ADS)

Kovacs, Marinel; Seghedi, Ioan; Yamamoto, Masatsugu; Fülöp, Alexandrina; Pécskay, Zoltán; Jurje, Maria

2017-12-01

We present the first comprehensive study of Miocene volcanic rocks of the Oaş-Gutâi Volcanic Zone (OGVZ), Romania, which are exposed in the eastern Transcarpathian Basin (TB), within the Eastern Alpine-Western Carpathian-Northern Pannonian (ALCAPA) block. Collision between the ALCAPA block and Europe at 18-16 Ma produced the Carpathian fold-and-thrust belt. This was followed by clockwise rotation and an extensional regime forming core complexes of the separated TB fragment. Based on petrographic and geochemical data, including Srsbnd Nd isotopic compositions and Ksbnd Ar ages, we distinguish three types of volcanic activity in the OGVZ: (1) early Miocene felsic volcanism that produced caldera-related ignimbrites in the Gutâi Mountains (15.4-14.8 Ma); (2) widespread middle-late Miocene intermediate/andesitic volcanism (13.4-7.0 Ma); and (3) minor late Miocene andesitic/rhyolitic volcanism comprising the Oraşu Nou rhyolitic volcano and several andesitic-dacitic domes in the Oaş Mountains (11.3-9.5 Ma). We show that magma evolution in the OGVZ was controlled by assimilation-fractional crystallization and magma-mixing processes within an interconnected multi-level crustal magmatic reservoir. The evolution of volcanic activity within the OGVZ was controlled by the geodynamics of the Transcarpathian Basin. The early felsic and late intermediate Miocene magmas were emplaced in a post-collisional setting and were derived from a mantle source region that was modified by subduction components (dominantly sediment melts) and lower crust. The style of volcanism within the eastern TB system exhibits spatial variations, with andesitic composite volcanoes (Gutâi Mountains) observed at the margins, and isolated andesitic-rhyolitic monogenetic volcanoes (Oaş Mountains) in the center of the basin.

The ELSA tephra stack: Volcanic activity in the Eifel during the last 500,000 years

NASA Astrophysics Data System (ADS)

Förster, Michael W.; Sirocko, Frank

2016-07-01

Tephra layers of individual volcanic eruptions are traced in several cores from Eifel maar lakes, drilled between 1998 and 2014 by the Eifel Laminated Sediment Archive (ELSA). All sediment cores are dated by 14C and tuned to the Greenland interstadial succession. Tephra layers were characterized by the petrographic composition of basement rock fragments, glass shards and characteristic volcanic minerals. 10 marker tephra, including the well-established Laacher See Tephra and Dümpelmaar Tephra can be identified in the cores spanning the last glacial cycle. Older cores down to the beginning of the Elsterian, show numerous tephra sourced from Strombolian and phreatomagmatic eruptions, including the 40Ar/39Ar dated differentiated tephra from Glees and Hüttenberg. In total, at least 91 individual tephra can be identified since the onset of the Eifel volcanic activity at about 500,000 b2k, which marks the end of the ELSA tephra stack with 35 Strombolian, 48 phreatomagmatic and 8 tephra layers of evolved magma composition. Many eruptions cluster near timings of the global climate transitions at 140,000, 110,000 and 60,000 b2k. In total, the eruptions show a pattern, which resembles timing of phases of global sea level and continental ice sheet changes, indicating a relation between endogenic and exogenic processes.

Satellite Derived Volcanic Ash Product Inter-Comparison in Support to SCOPE-Nowcasting

NASA Astrophysics Data System (ADS)

Siddans, Richard; Thomas, Gareth; Pavolonis, Mike; Bojinski, Stephan

2016-04-01

In support of aeronautical meteorological services, WMO organized a satellite-based volcanic ash retrieval algorithm inter-comparison activity, to improve the consistency of quantitative volcanic ash products from satellites, under the Sustained, Coordinated Processing of Environmental Satellite Data for Nowcasting (SCOPEe Nowcasting) initiative (http:/ jwww.wmo.int/pagesjprogjsatjscopee nowcasting_en.php). The aims of the intercomparison were as follows: 1. Select cases (Sarychev Peak 2009, Eyjafyallajökull 2010, Grimsvötn 2011, Puyehue-Cordón Caulle 2011, Kirishimayama 2011, Kelut 2014), and quantify the differences between satellite-derived volcanic ash cloud properties derived from different techniques and sensors; 2. Establish a basic validation protocol for satellite-derived volcanic ash cloud properties; 3. Document the strengths and weaknesses of different remote sensing approaches as a function of satellite sensor; 4. Standardize the units and quality flags associated with volcanic cloud geophysical parameters; 5. Provide recommendations to Volcanic Ash Advisory Centers (VAACs) and other users on how to best to utilize quantitative satellite products in operations; 6. Create a "road map" for future volcanic ash related scientific developments and inter-comparison/validation activities that can also be applied to SO2 clouds and emergent volcanic clouds. Volcanic ash satellite remote sensing experts from operational and research organizations were encouraged to participate in the inter-comparison activity, to establish the plans for the inter-comparison and to submit data sets. RAL was contracted by EUMETSAT to perform a systematic inter-comparison of all submitted datasets and results were reported at the WMO International Volcanic Ash Inter-comparison Meeting to held on 29 June - 2 July 2015 in Madison, WI, USA (http:/ /cimss.ssec.wisc.edujmeetings/vol_ash14). 26 different data sets were submitted, from a range of passive imagers and spectrometers and

A Decade of Volcanic Observations from Aura and the A-Train

NASA Technical Reports Server (NTRS)

Carn, Simon A.; Krotkov, Nickolay Anatoly; Yang, Kai; Krueger, Arlin J.; Hughes, Eric J.; Wang, Jun; Flower, Verity; Telling, Jennifer

2014-01-01

Aura observations have made many seminal contributions to volcanology. Prior to the Aura launch, satellite observations of volcanic degassing (e.g., from TOMS) were mostly restricted to large eruptions. However, the vast majority of volcanic gases are released during quiescent 'passive' degassing between eruptions. The improved sensitivity of Aura OMI permitted the first daily, space-borne measurements of passive volcanic SO2 degassing, providing improved constraints on the source locations and magnitude of global SO2 emissions for input to atmospheric chemistry and climate models. As a result of this unique sensitivity to volcanic activity, OMI data were also the first satellite SO2 measurements to be routinely used for volcano monitoring at several volcano observatories worldwide. Furthermore, the Aura OMI SO2 data also offer unprecedented sensitivity to volcanic clouds in the UTLS, elucidating the transport, fate and lifetime of volcanic SO2 and providing critical input to aviation hazard mitigation efforts. Another major advance has been the improved vertical resolution of volcanic clouds made possible by synergy between Aura and other A-Train instruments (e.g., AIRS, CALIPSO, CloudSat), advanced UV SO2 altitude retrievals, and inverse trajectory modeling of detailed SO2 cloud maps. This altitude information is crucial for climate models and aviation hazards. We will review some of the highlights of a decade of Aura observations of volcanic activity and look ahead to the future of volcanic observations from space.

A new comprehensive database of global volcanic gas analyses

NASA Astrophysics Data System (ADS)

Clor, L. E.; Fischer, T. P.; Lehnert, K. A.; McCormick, B.; Hauri, E. H.

2013-12-01

Volcanic volatiles are the driving force behind eruptions, powerful indicators of magma provenance, present localized hazards, and have implications for climate. Studies of volcanic emissions are necessary for understanding volatile cycling from the mantle to the atmosphere. Gas compositions vary with volcanic activity, making it important to track their chemical variability over time. As studies become increasingly interdisciplinary, it is critical to have a mechanism to integrate decades of gas studies across disciplines. Despite the value of this research to a variety of fields, there is currently no integrated network to house all volcanic and hydrothermal gas data, making spatial, temporal, and interdisciplinary comparison studies time-consuming. To remedy this, we are working to establish a comprehensive database of volcanic gas emissions and compositions worldwide, as part of the Deep Carbon Observatory's DECADE (Deep Carbon Degassing) initiative. Volcanic gas data have been divided into two broad categories: 1) chemical analyses from samples collected directly at the volcanic source, and 2) measurements of gas concentrations and fluxes, such as remotely by mini-DOAS or satellite, or in-plume such as by multiGAS. The gas flux database effort is realized by the Global Volcanism Program of the Smithsonian Institution (abstract by Brendan McCormick, this meeting). The direct-sampling data is the subject of this presentation. Data from direct techniques include samples of gases collected at the volcanic source from fumaroles and springs, tephras analyzed for gas contents, filter pack samples of gases collected in a plume, and any other data types that involve collection of a sample. Data are incorporated into the existing framework of the Petrological Database, PetDB. Association with PetDB is advantageous as it will allow volcanic gas data to be linked to chemical data from lava or tephra samples, forming more complete ties between the eruptive products and the

Atmospheric chemistry in volcanic plumes.

PubMed

von Glasow, Roland

2010-04-13

Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

Application of ASAR-ENVISAT Data for Monitoring Andean Volcanic Activity : Results From Lastarria-Azufre Volcanic Complex (Chile-Argentina)

NASA Astrophysics Data System (ADS)

Froger, J.; Remy, D.; Bonvalot, S.; Franco Guerra, M.

2005-12-01

Since the pioneer study on Mount Etna by Massonnet et al., in 1995, several works have illustrated the promising potentiality of Synthetic Aperture Radar Interferometry (INSAR) for the monitoring of volcanoes. In the case of wide, remote or hazardous volcanic areas, in particular, INSAR represents a safer and more economic way to acquire measurements than from ground based geodetic networks. Here we present the preliminary results of an interferometric survey made with ASAR-ENVISAT data on a selection of South American volcanoes where deformation signals had been previously evidenced or are expected. An interesting result is the detection of a present-day active ground deformation on the Azufre-Lastarria area (Chile-Argentina) indicating that process, identified during 1998-2000 by Pritchard and Simmons (2004) from ERS data, is still active. The phase signal visible on ASAR interferograms (03/2003-06/2005) is roughly elliptical with a 45 km NNE-SSW major axis. Its amplitude increases as a function of time and is compatible with ground uplift in the line of sight of the satellite. The ASAR time series (up to 840 days, 7 ASAR images) indicates variable deformation rate that might confirm the hypothesis of a non uniform deformation process. We investigated the origin and the significance of the deformation using various source modelling strategies (analytical and numerical). The observed deformation can be explained by the infilling of an elliptical magmatic reservoir lying between 7 and 10 km depth. The deformation could represent the first stage of a new caldera forming as it is correlated with a large, although subtle, topographic depression surrounded by a crown of monogenetic centers. A short wavelength inflation has also been detected on Lastaria volcano. It could result from the on-going infilling of a small subsurface magmatic reservoir, eventually supplied by the deeper one. All these observations point out the need of a closer monitoring of this area in

Submarine Volcanic Eruptions and Potential Analogs for Venus

NASA Technical Reports Server (NTRS)

Wilson, L.; Mouginismark, P. J.; Fryer, P.; Gaddis, L. R.

1985-01-01

As part of an analysis program to better understand the diversity of volcanic processes on the terrestrial planets, an investigation of the volcanic landforms which exist on the Earth's ocean floor was initiated. In part, this analysis is focused toward gaining a better understanding of submarine volcanic landforms in their own right, but also it is hoped that these features may show similarities to volcanic landforms on Venus, due to the high ambient water (Earth) and atmospheric (Venus) pressures. A series of numerical modelling experiments was performed to investigate the relative importance of such attributes as water pressure and temperature on the eruption process, and to determine the rate of cooling and emplacement of lava flows in the submarine environment. Investigations to date show that the confining water pressure and the buoyancy effects of the surrounding water significantly affect the styles of volcanism on the ocean floor. In the case of Venusian volcanism, confining pressures will not be as great as that found at the ocean's abyssal plains, but nevertheless the general trend toward reducing magma vesiculation will hold true for Venus as well as the ocean floor. Furthermore, other analogs may also be found between submarine volcanism and Venusian activity.

Distinguishing Phenocrysts From Xenocrysts; Dating the Onset of Volcanic Activity on the Isle of Rum, Scotland.

NASA Astrophysics Data System (ADS)

Troll, V. R.; Nicoll, G. R.; Emeleus, H. C.; Donaldson, C. H.

2005-12-01

Major volcanic activity on the Isle of Rum started with eruption of rhyodacite, now preserved as intrusive and extrusive parts of the intra-caldera succession. A thick sequence of intra-caldera ignimbrites and sedimentary breccias are preserved in the north and south of the island. Twenty feldspar crystals of the rhyodacite were dated using Ar/Ar and yielded a mean apparent age of 60.83 ± 0.27Ma (MSWD = 3.4), consistent with previously published dates for the crosscutting (i.e. younger) ultrabasic-layered intrusion of 60.53 ± 0.08Ma, Hamilton et al., (1998, Nature). On an age versus probability plot the feldspars do not, however, show a simple Gaussian distribution, but a major peak at 60.33Ma and two smaller shoulders at approx 61.4Ma and 63Ma. Our preliminary interpretation of the older ages is that they include a) xenocrysts derived from earlier Tertiary plutonics (61.4Ma peak) and b) older feldspars that have largely re-equilibrated within the rhyodacite magma chamber, possibly derived from Lewisian gneiss (63Ma peak). This may imply a residence time of these xenocrysts in the magma chamber of up to several years; cf. Gansecki et al., (1996, Earth Planet Sci. Lett.). The youngest and strongest age peak at 60.33Ma is suggested to represent the rhyodacite event. The oxygen isotope composition of the rhyodacite feldspars (6.88 ‰) is in the range of magmatic phenocrysts (6-7.5 ‰) and Lewisian gneisses (5-8 ‰) and well above the very low oxygen isotope values usually associated with high-T alteration. Hydrothermal overprint due to the layered ultrabasic intrusion was therefore probably minimal. We suggest the 60.33 ± 0.21Ma crystal age represents the rhyodacite eruption/intrusion event, implying that the ultrabasic-layered suite was already forming at depth and emplaced at shallow structural levels quickly thereafter. These new age dates tie in very well with recent work by Chambers et al., (2005, Lithos), highlighting a very quick succession of events

Ice in Volcanic Clouds

NASA Astrophysics Data System (ADS)

Few, A. A.

2010-12-01

It is widely recognized that lightning activity in thunderstorm clouds is associated with ice in the clouds. In volcanic plumes the lower electrical discharges near the vent are clearly not associated with ice; however, the electrical discharges from the upper volcanic clouds very likely are associated with ice. There is ample water in volcanic plumes and clouds. The explosive volcanic eruption is produced by volatile components in the rising magma. Researchers estimate that the water content of the volatiles is up to 99% by mole; other gases are mainly sulfur and chlorine species. These volatiles carry with them a wide range of hot magma melts and solids, importantly silicate particles and tephra. The more massive components fall out near the vent carrying with them much of the heat from the plume; these large components are not in thermodynamic equilibrium with the gases, ash, and lapilli; thus the heat removed does not lower the temperature of the materials carried aloft in the plume. Upward motion is initially provided by the thrust from the volcanic eruption, then by buoyancy of the hot plume. The rising plume is cooled by entrainment of environmental air, which contains water, and by adiabatic expansion; the plume transitions into a volcanic cloud. Further lifting and cooling produces supercooled water droplets (T ~ -5 C) in a limited zone (z ~ 9 km) before the fast updraft (~ 60 m/s) rapidly transforms them into ice. Computer models of volcanic clouds that include water and ice microphysics indicate that the latent heat of condensation is not significant in cloud dynamics because it occurs in a region where buoyancy is provided by the original hot plume material. The latent heat of ice formation occurs at higher and colder levels and seems to contribute to the final lifting of the cloud top by ~1.5km. Laboratory results indicate that the fine silicate ash particles, which are abundant, are good ice nuclei, IN. Because of the abundance of the silicate ash

[Effects of volcanic eruptions on human health in Iceland. Review].

PubMed

Gudmundsson, Gunnar; Larsen, Guðrun

2016-01-01

Volcanic eruptions are common in Iceland and have caused health problems ever since the settlement of Iceland. Here we describe volcanic activity and the effects of volcanic gases and ash on human health in Iceland. Volcanic gases expelled during eruptions can be highly toxic for humans if their concentrations are high, irritating the mucus membranes of the eyes and upper respiratory tract at lower concentrations. They can also be very irritating to the skin. Volcanic ash is also irritating for the mucus membranes of the eyes and upper respiratory tract. The smalles particles of volcanic ash can reach the alveoli of the lungs. Described are four examples of volcanic eruptions that have affected the health of Icelanders. The eruption of Laki volcanic fissure in 1783-1784 is the volcanic eruption that has caused the highest mortality and had the greatest effects on the well-being of Icelanders. Despite multiple volcanic eruptions during the last decades in Iceland mortality has been low and effects on human health have been limited, although studies on longterm effects are lacking. Studies on the effects of the Eyjafjallajökul eruption in 2010 on human health showed increased physical and mental symptoms, especially in those having respiratory disorders. The Directorate of Health in Iceland and other services have responded promptly to recurrent volcanic eruptions over the last few years and given detailed instructions on how to minimize the effects on the public health. Key words: volcanic eruptions, Iceland, volcanic ash, volcanic gases, health effects, mortality. Correspondence: Gunnar Guðmundsson, ggudmund@landspitali.is.

Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development

NASA Astrophysics Data System (ADS)

Korteniemi, J.; Kukkonen, S.

2018-04-01

Outflow channel formation on the eastern Hellas rim region is traditionally thought to have been triggered by activity phases of the nearby volcanoes Hadriacus and Tyrrhenus Montes: As a result of volcanic heating subsurface volatiles were mobilized. It is, however, under debate, whether eastern Hellas volcanism was in fact more extensive, and if there were volcanic centers separate from the identified central volcanoes. This work describes previously unrecognized structures in the Niger-Dao Valles outflow channel complex. We interpret them as volcanic edifices: cones, a shield, and a caldera. The structures provide evidence of an additional volcanic center within the valles and indicate volcanic activity both prior to and following the formation of the outflow events. They expand the extent, type, and duration of volcanic activity in the Circum-Hellas Volcanic Province and provide new information on interaction between volcanism and fluvial activity.

Dating of the youngest volcanoes of Ardeche (Massif Central, France) using 40Ar/39Ar and unspiked K/Ar

NASA Astrophysics Data System (ADS)

Nomade, Sebastien; Sasco, Romain; Guillou, Herve; Scao, Vincent; Kissel, Catherine; Genty, Dominique

2014-05-01

Since the first description in 1778 of the relationship between prismatic basaltic flow and volcano in the high valleys of the Ardèche (Faujas Saint-Font, 1778), "L'Ardèche", a small region at the south-west of Massif Central, became worldwide famous among volcanologists. This volcanism is found dispersed over an area of more than 20 km2 and is made of strombolian cones and prismatic flows filling NS to NW-SE valleys. This volcanism has then been considered as one of the most recent one in the entire Massif Central (40 ka to 170 ka, TL ages, Guérin et al., 2007). Unfortunately and despite several attempts over the last 25 years this volcanism has never been dated using radio-isotopic methods. The two main reasons usually advocated to explain this lack of success were the young age of the volcanism itself and the large amounts of mantle and lower crust xenoliths in the lavas (Guérin et al., 2007). In this contribution, we will present combined 40Ar/39Ar ages and unspiked K/Ar results obtained on five lava flows. The obtained ages range from 26 ± 5.5 ka to 55 ± 6.0 ka (1s, full propagated uncertainty relative to ACS-2 at 1.194Ma, Nomade et al., 2005). The ages from three of the investigated lava flows coming from distinct cones, are clustered between 26 ± 5.5 ka and 34 ± 4 ka. These cones are found stretched along a NW-SE tectonic accident. These first radio-isotopic constraints prove that the volcanic activity occurred during the last glacial period and is as young as "la chaîne de Puys" located in the northern part of the Massif Central. Incidentally, the volcanic activity is contemporaneous with the first Aurignacian occupation and related art found in the Chauvet cave (37-29 ka, Valladas et al., 2005) localized only 35 km SE. Based on both the spatial and chronological coincidences reported above we suggest that the Aurignacian population(s) that lived in this area have witnessed one or several of these eruptions.

40Ar/39Ar and unspiked 40K-40Ar dating of upper Pleistocene volcanic activity in the Bas-Vivarais (Ardèche, France)

NASA Astrophysics Data System (ADS)

Sasco, Romain; Guillou, Hervé; Nomade, Sébastien; Scao, Vincent; Maury, René C.; Kissel, Catherine; Wandres, Camille

2017-07-01

Fifteen basanitic and tephritic flows from Bas-Vivarais, the youngest volcanic field in the French Massif Central together with the Chaîne des Puys, were dated by 40Ar/39Ar and 40K-40Ar on separated groundmass, and studied for paleomagnetism. An almost systematic discrepancy between the two types of ages is observed, the 40K-40Ar method providing ages up to 8.5 times the 40Ar/39Ar ones. Microscopic observations and geochemical analyses lead us to conclude that most of the K-Ar ages measured on Bas-Vivarais samples are in error due to extraneous argon originating from contamination by xenocrysts from disintegrated crustal and mantle xenoliths. However, 40Ar/39Ar experiments do not evidence any excess argon, suggesting two possibilities: 1, the extraneous argon contribution was eliminated during the pre-degassing of the samples at 600 °C prior to the step heating experiments, 2 - K-Ar ages may be older because larger quantities of xenocrysts, potential carriers of extraneous argon were involved in the K-Ar experiments than in the 40Ar/39Ar ones. 40Ar/39Ar ages are thus little or not affected by contamination and provide reliable ages for the studied volcanoes. Combined 40Ar/39Ar datings and magnetic directions for each flow point out to three successive stages in the volcanic evolution of Bas-Vivarais. Stage 1, limited to the northern part of the field, has a mean age of 187.3 ± 19.0 ka. In its southern part, Stages 2 and 3 emplaced magmas at 31.1 ± 3.9 ka and 23.9 ± 8.1 ka, respectively. These two last stages are consistent with available 14C dates but not with previous thermoluminescence data.

Geochemical and Isotopic Evidences of the Magmatic Sources in the Eastern Sector of the Trans-Mexican Volcanic Belt: Xihuingo-Chichicuautla Volcanic Field

NASA Astrophysics Data System (ADS)

Valadez, S.; Martinez-serrano, R.; Juarez-Lopez, K.; Solis-Pichardo, G.; Perez-Arvizu, O.

2011-12-01

The study of magmatism in the Trans-Mexican Volcanic Belt (TMVB) has great importance due to several features such as its obliquity with respect to the Middle American Trench and its petrological and geochemical variability, which are not common in most typical volcanic arcs. Although several papers have contributed significantly to the understanding of most important magmatic processes in this province, there are still several questions such as the characterization of magmatic sources. In the present work, we provide new stratigraphic, petrographic, geochemical and Sr, Nd and Pb isotopic data as well as some K-Ar age determinations from the Xihuingo-Chichicuautla volcanic field (XCVF), located at the eastern part of the TMVB, with the aim to identify the magmatic sources that produced the main volcanic rocks. The volcanic structures in the XCVF are divided in two main groups according to the petrographic and geochemical compositions: 1) dacitic domes, andesitic lava flows and some dacitic-rhyolitic ignimbrites and 2) scoria cones, shield volcanoes and associated lava flows of basalt to basaltic-andesite composition. Distribution of most volcanic structures is probably controlled by NE-SW fault and fractures system. This fault system was studied by other authors who established that volcanic activity started ca. 13.5 Ma ago, followed by a volcanic hiatus of ca. 10 Ma, and the late volcanic activity began ca. 3 to 1 Ma. In this work we dated 2 rock samples by K-Ar method, which yielded ages of 402 and 871 Ka, which correspond to the most recent volcanic activity in this study area. The volcanic rocks of the XCVF display compositions from basalts to rhyolites but in general all rocks show trace element patterns typical of magmatic arcs. However, we can identify two main magmatic sources: a depleted magmatic source represented by dacitic-andesitic rocks which present a LILE enrichment with respect to HFSE indicating that a magmatic source was modified by fluids

Volcanic Plume Measurements with UAV (Invited)

NASA Astrophysics Data System (ADS)

Shinohara, H.; Kaneko, T.; Ohminato, T.

2013-12-01

Volatiles in magmas are the driving force of volcanic eruptions and quantification of volcanic gas flux and composition is important for the volcano monitoring. Recently we developed a portable gas sensor system (Multi-GAS) to quantify the volcanic gas composition by measuring volcanic plumes and obtained volcanic gas compositions of actively degassing volcanoes. As the Multi-GAS measures variation of volcanic gas component concentrations in the pumped air (volcanic plume), we need to bring the apparatus into the volcanic plume. Commonly the observer brings the apparatus to the summit crater by himself but such measurements are not possible under conditions of high risk of volcanic eruption or difficulty to approach the summit due to topography etc. In order to overcome these difficulties, volcanic plume measurements were performed by using manned and unmanned aerial vehicles. The volcanic plume measurements by manned aerial vehicles, however, are also not possible under high risk of eruption. The strict regulation against the modification of the aircraft, such as installing sampling pipes, also causes difficulty due to the high cost. Application of the UAVs for the volcanic plume measurements has a big advantage to avoid these problems. The Multi-GAS consists of IR-CO2 and H2O gas analyzer, SO2-H2O chemical sensors and H2 semiconductor sensor and the total weight ranges 3-6 kg including batteries. The necessary conditions of the UAV for the volcanic plumes measurements with the Multi-GAS are the payloads larger than 3 kg, maximum altitude larger than the plume height and installation of the sampling pipe without contamination of the exhaust gases, as the exhaust gases contain high concentrations of H2, SO2 and CO2. Up to now, three different types of UAVs were applied for the measurements; Kite-plane (Sky Remote) at Miyakejima operated by JMA, Unmanned airplane (Air Photo Service) at Shinomoedake, Kirishima volcano, and Unmanned helicopter (Yamaha) at Sakurajima

Exploring Interactions Between Subduction Zone Earthquakes and Volcanic Activity in the South Central Alaskan Subduction Zone

NASA Astrophysics Data System (ADS)

Lanagan, K. M.; Richardson, E.

2012-12-01

Although great earthquakes such as the recent moment-magnitude (M) 9 Tohoku-Oki earthquake have been shown to trigger remote seismicity in volcanoes, the extent to which subduction zone earthquakes can trigger shallow seismic swarms at volcanoes is largely unexplored. Unknowns in this relationship include the upper limit of distance, the lower limit of magnitude, the upper time limit between events, and the effects of rupture directivity. We searched the Advanced National Seismic System earthquake catalog from 1989 - 2011 for correlations in space and time between M > 5.0 earthquakes in the south central Alaskan subduction zone (between 58.5°N and 62.5°N, and 150.7°W and 154.7°W) and volcanic activity at Mt. Redoubt, Mt. Iliamna, and Mt. Spurr volcanoes. There are 48 earthquakes M > 5 in this catalog; five of these are M > 6. The depths of the 48 M>5 events range from 49km to 220km, and they are all between 100km and 350km of the three volcanoes. Preliminary analysis of our catalog shows that four of the five M > 6 earthquakes are followed by a volcanic earthquake swarm at either Redoubt or Spurr within 100 days, and three of them are followed by a volcanic earthquake swarm within a month. None of these events correlated in space and time with swarms at Mt. Iliamna. We are also searching for swarms and moderate earthquakes occurring in time windows far removed from each other. The likeliest case of remotely triggered seismicity in our search area to date occurred on January 24 2009, when a magnitude 5.8 earthquake beneath the Kenai Peninsula at 59.4°N, 152.8°W, and 95km depth was immediately followed by an increase of volcanic activity at Mt. Redoubt approximately 153km away. The first swarm began on Jan 25 2009. On Jan 30 2009, volcanologists at the Alaskan Volcano observatory determined the increased volcanic seismicity was indicative of an impending eruption. Mt. Redoubt erupted on March 15 2009. Proposed mechanisms for triggering of volcanoes by

Satellite observations of the impact of weak volcanic activity on marine clouds

NASA Astrophysics Data System (ADS)

Gassó, Santiago

2008-07-01

Because emissions from weak volcanic eruptions tend to remain in the low troposphere, they may have a significant radiative impact through the indirect effect on clouds. However, this type of volcanic activity is underreported and its global impact has been assessed only by model simulations constrained with very limited observations. First observations of the impact of high-latitude active volcanoes on marine boundary layer clouds are reported here. These observations were made using a combination of standard derived products and visible images from the MODIS, AMSR-E and GOES detectors. Two distinctive effects are identified. When there is an existing boundary layer cloud deck, an increase in cloud brightness and a decrease in both cloud effective radius and liquid water content were observed immediately downwind of the volcanoes. The visible appearance of these "volcano tracks" resembles the effect of man-made ship tracks. When synoptic conditions favor low cloudiness, the volcano plume (or volcano cloud) increases significantly the cloud cover downwind. The volcano cloud can extend for hundreds of kilometers until mixing with background clouds. Unlike violent eruptions, the volcano clouds reported here (the Aleutian Islands in the North Pacific and the South Sandwich Islands in the South Atlantic) have retrieved microphysical properties similar to those observed in ship tracks. However, when comparing the volcano clouds from these two regions, liquid water content can decrease, increase or remain unchanged with respect to nearby unperturbed clouds. These differences suggest that composition at the source, type of eruption and meteorological conditions influence the evolution of the cloud.

Assessment of the atmospheric impact of volcanic eruptions

NASA Technical Reports Server (NTRS)

Sigurdsson, H.

1988-01-01

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

Structural features related to the volcanic gases in Southern Okinawa Trough

NASA Astrophysics Data System (ADS)

Wang, H. F.; Hsu, S. K.; Tsia, C. H.; Chen, S. C.; Wu, M. F.

2016-12-01

The Okinawa Trough is a rifted back-arc basin, heavily sedimented and formed in an intracontinental rift zone behind the Ryukyu trench-arc system. The Southern Okinawa Trough (SOT) east of Taiwan is the place where post-collisional extension happened. The collision moved southwestward and the Ryukyu trench-arc extension westward, Arc volcanism is dominant in the Northern Ryukyu volcanic arc and back-arc volcanism in the Southern Okinawa Trough. Marine geophysical data including side-scan sonar (SSS), sub-bottom profiler (SBP) and echo sounder system (EK60) data are used in this study. Active fluid activities out of seafloor are obvious from various images observed on these data, such as gas plumes. These hydrothermal vents have been located at a water depth of 1400 m. Our preliminary results show that gas seepage structures appear in the location where is a week zone, such as a normal fault in the slope. The hydrothermal activity within the Okinawa Trough is associated with volcanism located in rift zones in the Southern Okinawa Trough. However, the origin of the submarine hydrothermal fluids within the Okinawa Trough is diverse with contributions from volcanic, sedimentary and magmatic sources, needed further investigations.

Morpho-structural evolution of a volcanic island developed inside an active oceanic rift: S. Miguel Island (Terceira Rift, Azores)

NASA Astrophysics Data System (ADS)

Sibrant, A. L. R.; Hildenbrand, A.; Marques, F. O.; Weiss, B.; Boulesteix, T.; Hübscher, C.; Lüdmann, T.; Costa, A. C. G.; Catalão, J. C.

2015-08-01

The evolution of volcanic islands is generally marked by fast construction phases alternating with destruction by a variety of mass-wasting processes. More specifically, volcanic islands located in areas of intense regional deformation can be particularly prone to gravitational destabilisation. The island of S. Miguel (Azores) has developed during the last 1 Myr inside the active Terceira Rift, a major tectonic structure materializing the present boundary between the Eurasian and Nubian lithospheric plates. In this work, we depict the evolution of the island, based on high-resolution DEM data, stratigraphic and structural analyses, high-precision K-Ar dating on separated mineral phases, and offshore data (bathymetry and seismic profiles). The new results indicate that: (1) the oldest volcanic complex (Nordeste), composing the easternmost part of the island, was dominantly active between ca. 850 and 750 ka, and was subsequently affected by a major south-directed flank collapse. (2) Between at least 500 ka and 250 ka, the landslide depression was massively filled by a thick lava succession erupted from volcanic cones and domes distributed along the main E-W collapse scar. (3) Since 250 kyr, the western part of this succession (Furnas area) was affected by multiple vertical collapses; associated plinian eruptions produced large pyroclastic deposits, here dated at ca. 60 ka and less than 25 ka. (4) During the same period, the eastern part of the landslide scar was enlarged by retrogressive erosion, producing the large Povoação valley, which was gradually filled by sediments and young volcanic products. (5) The Fogo volcano, in the middle of S. Miguel, is here dated between ca. 270 and 17 ka, and was affected by, at least, one southwards flank collapse. (6) The Sete Cidades volcano, in the western end of the island, is here dated between ca. 91 and 13 ka, and experienced mutliple caldera collapses; a landslide to the North is also suspected from the presence of a

AVAL - The ASTER Volcanic Ash Library

NASA Astrophysics Data System (ADS)

Williams, D.; Ramsey, M. S.

2016-12-01

. These results provide particle size distributions within actively-erupting volcanic plumes for the first time in high resolution, and the petrologic information is being studied to understand the underlying eruptive processes observed.

Neotectonic reactivation of the western section of the Malargüe fold and thrust belt (Tromen volcanic plateau, Southern Central Andes)

NASA Astrophysics Data System (ADS)

Sagripanti, Lucía; Rojas Vera, Emilio A.; Gianni, Guido M.; Folguera, Andrés; Harvey, Jonathan E.; Farías, Marcelo; Ramos, Victor A.

2015-03-01

This study examines the neotectonic deformation and development of the Tromen massif, a Quaternary retroarc volcanic field located in the western section of the Malargüe fold and thrust belt in the Southern Central Andes. The linkages between neotectonic deformation in the intra-arc zone and the recent retroarc structures of the Tromen volcanic plateau are not clearly understood. These retroarc deformations affect the mid-section of the fold and thrust belt, leaving to the east a 200 km-wide deformed zone that can be considered inactive over the last 12-10 Ma. This out-of-sequence deformation west of the orogenic front area has not been previously addressed in detail. In this study, exhaustive mapping is used to describe and discriminate structures with a neotectonic component from those fossilized by Pleistocene strata. Two balanced cross-sections are constructed showing the distribution of the youngest deformations and their relation to pre-Miocene structures. An important means for evaluating this is the morphometric and morphological analyses that allowed identification of perturbations in the fluvial network associated with active structures. In a broader perspective, neotectonic activity in the fold and thrust belt is discussed and inferred to be caused by local mechanical weakening of the retroarc zone, due to injection of asthenospheric material evidenced by magnetotelluric surveys. Thus, deformation imposed by the oblique convergence between South American and Nazca plates, while to the south being limited to the Liquiñe-Ofqui fault system that runs through the arc zone, in the retroarc area is located at the site of magmatic emplacement, presumably in association with a thermally weakened-upper crust. This control exemplifies the relationship that exists between surficial processes, magmatic emplacement and upper asthenospheric dynamics in the Southern Central Andes.

The eruption history of the quaternary Eifel volcanic fields: Implications from the ELSA - Tephra - Stack

NASA Astrophysics Data System (ADS)

Förster, Michael; Sirocko, Frank

2015-04-01

periodically, peaking at 450 000 to 500 000, 140 000, 100 000 and 50 000 b2k in the West Eifel Volcanic Field and 400 000, 200 000, 150 000 and 12 900 b2k in the East Eifel Volcanic Field. These phases are seperated by long dormant intervals and cluster around times of climate and sea level changes. The youngest phase of intense activity in the West Eifel Volcanic Field occured from ~60 000 to 27 800 b2k. All young maar volcanoes with open maar lakes like the Pulvermaar, Meerfelder Maar and Dauner Maar Group erupted in this cluster. Only one maar postdates this interval of increased activity, the 11 000 b2k Ulmener Maar. References Sirocko, F., Dietrich, S., Veres, D., Grootes, P. M., Schaber-Mohr, K., Seelos, K., Nadeau, M.-J., Kromer, B., Rothacker, L., Röhner, M., Krbetschek, M., Appleby, P., Hambach, U., Rolf, C., Sudo, M., & Grim, S. (2013). Multi-proxy dating of Holocene maar lakes and Pleistocene dry maar sediments in the Eifel, Germany. Quaternary Science Reviews, 62, 56-76. van den Bogaard, P., Hall, C. M., Schmincke, H. U., & York, D. (1989). Precise single-grain 40Ar/39 Ar dating of a cold to warm climate transition in Central Europe. Nature 342, 523 - 525 van den Bogaard, P. & Schmincke, H. U. (1990). Die Entwicklungsgeschichte des Mittelrheinraumes und die Eruptionsgeschichte des Osteifel-Vulkanfeldes. Rheingeschichte zwischen Mosel und Maas. deuqua-Führer, 1, 166-190. Zolitschka, B. (1998). A 14,000 year sediment yield record from western Germany based on annually laminated lake sediments. Geomorphology, 22(1), 1-17.

Geologic map of the Lassen region, Cascade Range, USA

USGS Publications Warehouse

Clynne, Michael; Muffler, L.J.

1990-01-01

A preliminary geologic map at 1:50,000 of the Lassen region encompasses 1400 km2. The map displays many small, monogenetic volcanoes of basalt to andesite as well as three major late Pliocene and Quaternary volcanic centers that have erupted products ranging from basaltic andesite to rhyolite. The youngest of these volcanic centers is the Lassen volcanic center, active from 600,000 years B.P. to the present. A major caldera formed at 400,000 years B.P. and has subsequently been filled with silicic lavas. The Lassen geothermal system, which consists of a central vapor-dominated reservoir at a temperature of 235??C underlain by a reservoir of hot water, is centered at Bumpass Hell within Lassen Volcanic National Park.

Soil gas 222Rn and volcanic activity at El Hierro (Canary Islands) before and after the 2011 submarine eruption

NASA Astrophysics Data System (ADS)

Padilla, G.; Hernández, P. A.; Padrón, E.; Barrancos, J.; Melián, G.; Dionis, S.; Rodríguez, F.; Nolasco, D.; Calvo, D.; Hernández, I.; Pereza, M. D.; Pérez, N. M.

2012-04-01

El Hierro (278 km2) is the southwesternmost island of the Canarian archipelago. From June 19, 2011 to January 2012, more than 11,950 seismic events have been detected by the seismic network of IGN. On 10 October 2011 the earthquake swarm changed its behaviour and produced a harmonic tremor due to magma movement, indicating that a submarine eruption located at 2 km south of La Restinga had started which is still in progress. Since 2003, the ITER Environmental Research Division now integrated in the Instituto Volcanológico de Canarias, INVOLCAN, has regularly performed soil gas surveys at El Hierro as a geochemical tool for volcanic surveillance. Among the investigated gases, soil gas radon (222Rn) and thoron (220Rn) have played a special attention. Both gases are characterized to ascend towards the surface mainly through cracks or faults via diffusion or advection, mechanisms dependent of both soil porosity and permeability, which in turn vary as a function of the stress/strain changes at depth. Years before the starts of the volcanic-seismic crisis on July 17, 2011, a volcanic multidisciplinary surveillance program was implemented at El Hierro including discrete and continuous measurements of 222Rn and 220Rn. Two soil gas 222Rn surveys had been carried out at El Hierro in 2003 and 2011, and four continuous geochemical monitoring stations for 222Rn and 220Rn measurements had been installed (HIE02, HIE03, HIE04 and HIE08). Soil gas 222Rn surveys were carried out at the surface environment of El Hierro after selecting 600 sampling observation sites (about 40 cm depth). Geochemical stations measure 222Rn and 220Rn activities by pumping the gas from a PVC pipe inserted 1m in the ground and thermally isolated. The results of the 2003 and 2011 soil gas 222Rn surveys show clearly a relatively higher observed 222Rn activities in the surface environment on 2011 than those observed on 2003 when no anomalous seismicity were taking place beneath El Hierro. The observed

Youngest case of ductal carcinoma in situ arising within a benign phyllodes tumour: A case report.

PubMed

Chopra, Sharat; Muralikrishnan, Vummiti; Brotto, Maurizio

2016-01-01

Phyllodes tumour (PT) is a rare tumour of the female breast. The tumour clinically and radiologically mimics the features of a fibroadenoma. Ductal carcinoma in situ (DCIS) in the epithelial component of PT is a very rare finding. We present youngest ever case of a 23-year-old nulliparous woman with high-grade ductal carcinoma in situ arising within a benign phyllodes tumor. Macroscopically, it is a homogeneous tumour with solid components. Microscopically, it features typical leaf-like pattern with hypercellular stroma with high-grade ductal carcinoma in situ. To date, eight such rare cases of benign phyllodes tumour with ductal carcinoma in situ have been documented. We report the youngest case known in literature so far. As this is a very rare presentation, it poses several challenges in regard to both management and follow-up. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Holocene volcanism of the upper McKenzie River catchment, central Oregon Cascades, USA

USGS Publications Warehouse

Deligne, Natalia I.; Conrey, Richard M.; Cashman, Katharine V.; Champion, Duane E.; Amidon, William H.

2016-01-01

To assess the complexity of eruptive activity within mafic volcanic fields, we present a detailed geologic investigation of Holocene volcanism in the upper McKenzie River catchment in the central Oregon Cascades, United States. We focus on the Sand Mountain volcanic field, which covers 76 km2 and consists of 23 vents, associated tephra deposits, and lava fields. We find that the Sand Mountain volcanic field was active for a few decades around 3 ka and involved at least 13 eruptive units. Despite the small total volume erupted (∼1 km3 dense rock equivalent [DRE]), Sand Mountain volcanic field lava geochemistry indicates that erupted magmas were derived from at least two, and likely three, different magma sources. Single units erupted from one or more vents, and field data provide evidence of both vent migration and reoccupation. Overall, our study shows that mafic volcanism was clustered in space and time, involved both explosive and effusive behavior, and tapped several magma sources. These observations provide important insights on possible future hazards from mafic volcanism in the central Oregon Cascades.

Timing and compositional evolution of Late Pleistocene to Holocene volcanism within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia

NASA Astrophysics Data System (ADS)

Stelten, M. E.; Downs, D. T.; Dietterich, H. R.

2017-12-01

Harrat Rahat is one of the largest ( 20,000 km2) of 15 active Cenozoic volcanic fields that stretch 3,000 km along the western Arabian Peninsula from Yemen to Syria. The Harrat Rahat volcanic field is 310 km long (N-S) by 75 km wide (E-W), and is dominated by alkalic basalts with minor hawaiite, mugearite, benmoreite, and trachyte eruptives. The timing of volcanism within greater Harrat Rahat is poorly constrained, but field relations and geochronology indicate that northern Harrat Rahat hosted the most recent eruptions. To better constrain the timing and compositional evolution of Harrat Rahat during this recent phase, we present 743 geochemical analyses, 144 40Ar/39Ar ages, and 9 36Cl exposure ages for volcanic strata from northernmost Harrat Rahat. These data demonstrate that volcanism has been ongoing from at least 1.2 Ma to the present, with the most recent eruption known from historical accounts at 1256 CE. Basalt has erupted persistently from 1.2 Ma to the present, but more evolved volcanism has been episodic. Benmoreite erupted at 1.1 Ma and between 550 to 400 ka. Trachytic volcanism has only occurred over the past 150 ka, with the most recent eruption at 5 ka. Aside from the well-documented basaltic eruption at 1256 CE, prior workers interpreted 6 additional basaltic eruptions during the Holocene. However, our 36Cl exposure ages demonstrate that these erupted between 60 to 13 ka. Interestingly, in the northern part of our field area, where the spatial density of volcanic vents is low, young volcanism (<150 ka) is dominated by basaltic eruptions. Conversely, young volcanism in the southern part of our field area, where volcanic vent density is high, is dominated by trachyte. This observation is consistent with a process wherein the time-integrated effects of basaltic influx into the crust in the south produced a mafic intrusive complex, through which younger basaltic magmas cannot ascend. Instead, these magmas stall and produce trachyte, likely through

Evidence of recent volcanic activity on the ultraslow-spreading Gakkel ridge.

PubMed

Edwards, M H; Kurras, G J; Tolstoy, M; Bohnenstiehl, D R; Coakley, B J; Cochran, J R

2001-02-15

Seafloor spreading is accommodated by volcanic and tectonic processes along the global mid-ocean ridge system. As spreading rate decreases the influence of volcanism also decreases, and it is unknown whether significant volcanism occurs at all at ultraslow spreading rates (<1.5 cm yr(-1)). Here we present three-dimensional sonar maps of the Gakkel ridge, Earth's slowest-spreading mid-ocean ridge, located in the Arctic basin under the Arctic Ocean ice canopy. We acquired this data using hull-mounted sonars attached to a nuclear-powered submarine, the USS Hawkbill. Sidescan data for the ultraslow-spreading (approximately 1.0 cm yr(-1)) eastern Gakkel ridge depict two young volcanoes covering approximately 720 km2 of an otherwise heavily sedimented axial valley. The western volcano coincides with the average location of epicentres for more than 250 teleseismic events detected in 1999, suggesting that an axial eruption was imaged shortly after its occurrence. These findings demonstrate that eruptions along the ultraslow-spreading Gakkel ridge are focused at discrete locations and appear to be more voluminous and occur more frequently than was previously thought.

Statistical analyses and characteristics of volcanic tremor on Stromboli Volcano (Italy)

NASA Astrophysics Data System (ADS)

Falsaperla, S.; Langer, H.; Spampinato, S.

A study of volcanic tremor on Stromboli is carried out on the basis of data recorded daily between 1993 and 1995 by a permanent seismic station (STR) located 1.8km away from the active craters. We also consider the signal of a second station (TF1), which operated for a shorter time span. Changes in the spectral tremor characteristics can be related to modifications in volcanic activity, particularly to lava effusions and explosive sequences. Statistical analyses were carried out on a set of spectra calculated daily from seismic signals where explosion quakes were present or excluded. Principal component analysis and cluster analysis were applied to identify different classes of spectra. Three clusters of spectra are associated with two different states of volcanic activity. One cluster corresponds to a state of low to moderate activity, whereas the two other clusters are present during phases with a high magma column as inferred from the occurrence of lava fountains or effusions. We therefore conclude that variations in volcanic activity at Stromboli are usually linked to changes in the spectral characteristics of volcanic tremor. Site effects are evident when comparing the spectra calculated from signals synchronously recorded at STR and TF1. However, some major spectral peaks at both stations may reflect source properties. Statistical considerations and polarization analysis are in favor of a prevailing presence of P-waves in the tremor signal along with a position of the source northwest of the craters and at shallow depth.

Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation

USGS Publications Warehouse

Praetorius, Summer; Mix, Alan; Jensen, Britta; Froese, Duane; Milne, Glenn A.; Wolhowe, Matthew; Addison, Jason A.; Prahl, Fred

2016-01-01

Observations of enhanced volcanic frequency during the last deglaciation have led to the hypothesis that ice unloading in glaciated volcanic terrains can promote volcanism through decompression melting in the shallow mantle or a reduction in crustal magma storage time. However, a direct link between regional climate change, isostatic adjustment, and the initiation of volcanism remains to be demonstrated due to the difficulty of obtaining high-resolution well-dated records that capture short-term climate and volcanic variability traced to a particular source region. Here we present an exceptionally resolved record of 19 tephra layers paired with foraminiferal oxygen isotopes and alkenone paleotemperatures from marine sediment cores along the Southeast Alaska margin spanning the last deglacial transition. Major element compositions of the tephras indicate a predominant source from the nearby Mt. Edgecumbe Volcanic Field (MEVF). We constrain the timing of this regional eruptive sequence to 14.6–13.1 ka. The sudden increase in volcanic activity from the MEVF coincides with the onset of Bølling–Allerød interstadial warmth, the disappearance of ice-rafted detritus, and rapid vertical land motion associated with modeled regional isostatic rebound in response to glacier retreat. These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity. Rapid sea surface temperature fluctuations and an increase in local salinity (i.e., δ18Osw) variability are associated with the interval of intense volcanic activity, consistent with a two-way interaction between climate and volcanism in which rapid volcanic response to ice unloading may in turn enhance short-term melting of the glaciers, plausibly via albedo effects on glacier ablation zones.

Sex-biased dispersal and volcanic activities shaped phylogeographic patterns of extant Orangutans (genus: Pongo).

PubMed

Nater, Alexander; Nietlisbach, Pirmin; Arora, Natasha; van Schaik, Carel P; van Noordwijk, Maria A; Willems, Erik P; Singleton, Ian; Wich, Serge A; Goossens, Benoit; Warren, Kristin S; Verschoor, Ernst J; Perwitasari-Farajallah, Dyah; Pamungkas, Joko; Krützen, Michael

2011-08-01

The Southeast Asian Sunda archipelago harbors a rich biodiversity with a substantial proportion of endemic species. The evolutionary history of these species has been drastically influenced by environmental forces, such as fluctuating sea levels, climatic changes, and severe volcanic activities. Orangutans (genus: Pongo), the only Asian great apes, are well suited to study the relative impact of these forces due to their well-documented behavioral ecology, strict habitat requirements, and exceptionally slow life history. We investigated the phylogeographic patterns and evolutionary history of orangutans in the light of the complex geological and climatic history of the Sunda archipelago. Our study is based on the most extensive genetic sampling to date, covering the entire range of extant orangutan populations. Using data from three mitochondrial DNA (mtDNA) genes from 112 wild orangutans, we show that Sumatran orangutans, Pongo abelii, are paraphyletic with respect to Bornean orangutans (P. pygmaeus), the only other currently recognized species within this genus. The deepest split in the mtDNA phylogeny of orangutans occurs across the Toba caldera in northern Sumatra and, not as expected, between both islands. Until the recent past, the Toba region has experienced extensive volcanic activity, which has shaped the current phylogeographic patterns. Like their Bornean counterparts, Sumatran orangutans exhibit a strong, yet previously undocumented structuring into four geographical clusters. However, with 3.50 Ma, the Sumatran haplotypes have a much older coalescence than their Bornean counterparts (178 kya). In sharp contrast to the mtDNA data, 18 Y-chromosomal polymorphisms show a much more recent coalescence within Sumatra compared with Borneo. Moreover, the deep geographic structure evident in mtDNA is not reflected in the male population history, strongly suggesting male-biased dispersal. We conclude that volcanic activities have played an important role in the

Mainshock-Aftershocks Clustering Detection in Volcanic Regions

NASA Astrophysics Data System (ADS)

Garza Giron, R.; Brodsky, E. E.; Prejean, S. G.

2017-12-01

Crustal earthquakes tend to break their general Poissonean process behavior by gathering into two main kinds of seismic bursts: swarms and mainshock-aftershocks sequences. The former is commonly related to volcanic or geothermal processes whereas the latter is a characteristic feature of tectonically driven seismicity. We explore the mainshock-aftershock clustering behavior of different active volcanic regions in Japan and its comparison to non-volcanic regions. We find that aftershock production in volcanoes shows mainshock-aftershocks clustering similar to what is observed in non-volcanic areas. The ratio of volanic areas that cluster in mainshock-aftershocks sequences vs the areas that do not is comparable to the ratio of non-volcanic regions that show clustering vs the ones that do not. Furthermore, the level of production of aftershocks for most volcanic areas where clustering is present seems to be of the same order of magnitude, or slightly higher, as the median of the non-volcanic regions. An interesting example of highly aftershock-productive volcanoes emerges from the 2000 Miyakejima dike intrusion. A big seismic cluster started to build up rapidly in the south-west flank of Miyakejima to later propagate to the north-west towards the Kozushima and Niijima volcanoes. In Miyakejima the seismicity showed a swarm-like signature with a constant earthquake rate, whereas Kozushima and Niijima both had expressions of highly productive mainshock-aftershocks sequences. These findings are surprising given the alternative mechanisms available in volcanic systems for releasing deviatoric strain. We speculate that aftershock behavior might hold a relationship with the rheological properties of the rocks of each system and with the capacity of a system to accumulate or release the internal pressures caused by magmatic or hydrothermal systems.

Understanding Volcanic Conduit Dynamics: from Experimental Fragmentation to Volcanic Eruptions

NASA Astrophysics Data System (ADS)

Arciniega-Ceballos, A.; Alatorre-Ibarguengoitia, M. A.; Scheu, B.; Dingwell, D. B.

2011-12-01

and the effects of such process on the conduit dynamics are independent of size. We first described the very-long period (VLP) and long-period (LP) signals, observed in many active volcanoes around the world, and from comparison of waveform characteristics with their experimental analogues (eLP and eVLP signals) we found remarkable similarities and equivalent physical meaning. Based on our experimental investigations and analysis of field data recorded during volcanic eruptions we may conclude that VLP signals are caused by the inflation-deflation behavior of the volcanic conduit due to the decompression process, and that LP signals are manly associated with cracking and fragmentation of the magmatic material (ash, magma and gas) filling the conduit and ascending to the surface. In addition, we accounted for the repetitive character of LP and VLP signals, as a consequence of contraction and dilatation of a steady non-destructive source mechanism, which systematically responds to pressure changes of the volcanic system.

Theory for Deducing Volcanic Activity From Size Distributions in Plinian Pyroclastic Fall Deposits

NASA Astrophysics Data System (ADS)

Iriyama, Yu; Toramaru, Atsushi; Yamamoto, Tetsuo

2018-03-01

Stratigraphic variation in the grain size distribution (GSD) of plinian pyroclastic fall deposits reflects volcanic activity. To extract information on volcanic activity from the analyses of deposits, we propose a one-dimensional theory that provides a formula connecting the sediment GSD to the source GSD. As the simplest case, we develop a constant-source model (CS model), in which the source GSD and the source height are constant during the duration of release of particles. We assume power laws of particle radii for the terminal fall velocity and the source GSD. The CS model can describe an overall (i.e., entire vertically variable) feature of the GSD structure of the sediment. It is shown that the GSD structure is characterized by three parameters, that is, the duration of supply of particles to the source scaled by the fall time of the largest particle, ts/tM, and the power indices of the terminal fall velocity p and of the source GSD q. We apply the CS model to samples of the Worzel D ash layer and compare the sediment GSD structure calculated by using the CS model to the observed structure. The results show that the CS model reproduces the overall structure of the observed GSD. We estimate the duration of the eruption and the q value of the source GSD. Furthermore, a careful comparison of the observed and calculated GSDs reveals new interpretation of the original sediment GSD structure of the Worzel D ash layer.

Lithospheric and Asthenospheric Contributions to Post-Collisional Volcanism in the Lesser Caucasus Mts (Armenia)

NASA Astrophysics Data System (ADS)

Sugden, P.; Savov, I. P.; Wilson, M.; Meliksetian, K.; Navasardyan, G.

2017-12-01

Continental collision zones remain the most enigmatic tectonic setting for volcanic activity on earth. The Lesser Caucasus Mts are host to widespread and unique intraplate volcanism, associated with the active Arabia-Eurasia continental collision. Volcanic products range from alkali basalts to rhyolites (including extensive ignimbrites), and occur as basaltic lava flow fields, large composite and shield volcanoes, and regions of distributed (mostly monogenetic) volcanism. Geomorphology, archaeology, and historical accounts suggest volcanic activity has extended in to the Holocene-historical period. The high quality of the exposures and the diversity of unaltered rock types makes Armenia an ideal natural laboratory for studying the sources of magmatism in an active continental collision zone. For the first time, we will present the mineral chemistry (ol, px, amph), whole rock major and trace element, and Sr-Nd isotope compositions of volcanic rocks from southernmost Armenia- namely the Gegham, Vardenis and Syunik volcanic highlands. We compare our dataset with the composition of post-collisional volcanic rocks elsewhere in the Arabia-Eurasia collision zone. Samples from S. Armenia are more mafic, more alkaline and more K2O rich. All volcanic rocks show negative HFSE anomalies and LILE and LREE enrichments reminiscent of continental volcanic arc settings. However, volcanic rocks in Southern Armenia are further enriched in some of the most incompatible trace elements, most notably LREE, Sr and P, and have higher La/Yb, Th/Yb, Ta/Yb, and more variable Th/Nb. Volcanic rocks from Eastern Anatolia and N. Armenia have Sr-Nd isotope compositions similar to those of the Mesozoic volcanic arc (87Sr/86Sr 0.7034-0.7045; 143Nd/144Nd 0.5128-0.5129), whereas samples from S. Armenia deviate towards more enriched compositions resembling a typical EM-I type reservoir (87Sr/86Sr 0.7041- 0.7047; 143Nd/144Nd 0.5127-0.5128). We argue that these distinctive geochemical characteristics

Volcanism in the Classroom.

ERIC Educational Resources Information Center

Albin, Edward F.

1993-01-01

Presents activities to familiarize junior high school students with the processes behind and reasons for volcanism, which is generally a planet's way of releasing excessive internal heat and pressure. Students participate in the creation of four important volcano-related simulations: a lava flow, a shield volcano, a cinder-cone volcano, and a…

Monitoring diffuse volcanic degassing during volcanic unrests: the case of Campi Flegrei (Italy).

PubMed

Cardellini, C; Chiodini, G; Frondini, F; Avino, R; Bagnato, E; Caliro, S; Lelli, M; Rosiello, A

2017-07-28

In volcanoes with active hydrothermal systems, diffuse CO 2 degassing may constitute the primary mode of volcanic degassing. The monitoring of CO 2 emissions can provide important clues in understanding the evolution of volcanic activity especially at calderas where the interpretation of unrest signals is often complex. Here, we report eighteen years of CO 2 fluxes from the soil at Solfatara of Pozzuoli, located in the restless Campi Flegrei caldera. The entire dataset, one of the largest of diffuse CO 2 degassing ever produced, is made available for the scientific community. We show that, from 2003 to 2016, the area releasing deep-sourced CO 2 tripled its extent. This expansion was accompanied by an increase of the background CO 2 flux, over most of the surveyed area (1.4 km 2 ), with increased contributions from non-biogenic source. Concurrently, the amount of diffusively released CO 2 increased up to values typical of persistently degassing active volcanoes (up to 3000 t d -1 ). These variations are consistent with the increase in the flux of magmatic fluids injected into the hydrothermal system, which cause pressure increase and, in turn, condensation within the vapor plume feeding the Solfatara emission.

Rapid onset of mafic magmatism facilitated by volcanic edifice collapse

NASA Astrophysics Data System (ADS)

Cassidy, M.; Watt, S. F. L.; Talling, P. J.; Palmer, M. R.; Edmonds, M.; Jutzeler, M.; Wall-Palmer, D.; Manga, M.; Coussens, M.; Gernon, T.; Taylor, R. N.; Michalik, A.; Inglis, E.; Breitkreuz, C.; Le Friant, A.; Ishizuka, O.; Boudon, G.; McCanta, M. C.; Adachi, T.; Hornbach, M. J.; Colas, S. L.; Endo, D.; Fujinawa, A.; Kataoka, K. S.; Maeno, F.; Tamura, Y.; Wang, F.

2015-06-01

Volcanic edifice collapses generate some of Earth's largest landslides. How such unloading affects the magma storage systems is important for both hazard assessment and for determining long-term controls on volcano growth and decay. Here we present a detailed stratigraphic and petrological analyses of volcanic landslide and eruption deposits offshore Montserrat, in a subduction zone setting, sampled during Integrated Ocean Drilling Program Expedition 340. A large (6-10 km3) collapse of the Soufrière Hills Volcano at ~130 ka was followed by explosive basaltic volcanism and the formation of a new basaltic volcanic center, the South Soufrière Hills, estimated to have initiated <100 years after collapse. This basaltic volcanism was a sharp departure from the andesitic volcanism that characterized Soufrière Hills' activity before the collapse. Mineral-melt thermobarometry demonstrates that the basaltic magma's transit through the crust was rapid and from midcrustal depths. We suggest that this rapid ascent was promoted by unloading following collapse.

Long-term risk in a recently active volcanic system: Evaluation of doses and indoor radiological risk in the quaternary Vulsini Volcanic District (Central Italy)

NASA Astrophysics Data System (ADS)

Capaccioni, B.; Cinelli, G.; Mostacci, D.; Tositti, L.

2012-12-01

Volcanic rocks in the Vulsini Volcanic District (Central Italy) contain high concentrations of 238U, 232Th and 40K due to subduction-related metasomatic enrichment of incompatible elements in the mantle source coupled with magma differentiation within the upper crust. Due to their favorable mechanical properties they have been extensively used for construction since the Etruscan age. In the old buildings of the Bolsena village, one of the most populated ancient village in the area, the major source of indoor radioactivity is 222Rn, a radioactive noble gas descendant of 238U. Direct 222Rn indoor measurements have detected extremely high values in the old center due to the combined effect of building materials, radon fluxes from the volcanic basement and low air exchange rates. In these cases the evaluated risk of developing lung cancer within a 75 year lifetime reaches up to 40% for ever smokers. Simulations of "standard rooms" built with different tuffs and lavas collected from the Vulsini Volcanic District have also provided estimations of the effective doses and lifetime risk for radiogenic cancer. Other than by the method adopted for calculation, the total evaluated risk for each volcanic rock depends on different parameters, such as: radionuclide content, radon emanation power, occupancy factor and air exchange rate. Occupancy factor and air exchange rate appear as the only controlling parameters able to mitigate the indoor radiological risk.

Resuspended volcanic ash from Katmai, Alaska

NASA Image and Video Library

2017-12-08

The Valley of Ten Thousand Smokes, located in Katmai National Park, forms a unique and ashen landscape. Encircled by volcanoes – both active and inactive – it has served as a perfect collection area for huge amounts of volcanic ash. According to the Alaska Historical Society (AHS), 2012 marked the centennial anniversary of the volcanic eruption that formed the valley, and led to the establishment, in 1918, of Katmai National Park. A massive eruption rocked the region on June 6, 1912 as the then-unknown volcano, Novarupta, became suddenly and violently active. According to the AHS, it erupted with “such force that mountains collapsed, ash darkened summer skies, earthquakes rocked population centers and were recorded as far away as Washington, D.C.” Glowing hot ash was reported to have smothered an area covering 40 square miles, and up to 700 feet deep. While the active volcanoes surrounding the valley - Novarupta, Mt. Mageik, Trident Volcano, Mt. Griggs, Mt. Martin and Mt. Katmai - have remained relatively quiescent, their ashen legacy continues to affect the landscape – and air traffic - even a century after it was laid down. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image on September 29, 2014. Volcanic ash from the Katmai region has been lifted aloft by strong winds, and is blowing to the southeast, over Shelikof Strait, Kodiak Island, and the Gulf of Alaska. Although such clouds are not from active volcanoes, the remobilized volcanic ash still provides a potential hazard to aircraft flying through the region. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team 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

Volcanic mercury in Pinus canariensis.

PubMed

Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

2013-08-01

Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg(-1)) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg(-1)). Thus, mercury emissions originating from the eruption remained only as a mark-in pyroclastic wounds-and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg(-1)) and bark (6.0 μg kg(-1)) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

Volcanic mercury in Pinus canariensis

NASA Astrophysics Data System (ADS)

Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

2013-08-01

Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg-1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg-1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg-1) and bark (6.0 μg kg-1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

Diffraction-limited Mid-infrared Integral Field Spectroscopy of Io's Volcanic Activity with ALES on the Large Binocular Telescope

NASA Astrophysics Data System (ADS)

Skrutskie, Michael F.; de Kleer, Katherine R.; Stone, Jordan; Conrad, Al; Davies, Ashley; de Pater, Imke; Leisenring, Jarron; Hinz, Philip; Skemer, Andrew; Veillet, Christian; Woodward, Charles E.; Ertel, Steve; Spalding, Eckhart

2017-10-01

The Arizona Lenslet for Exoplanet Spectroscopy (ALES) is an enhancement to the Large Binocular Telescope's mid-infrared imager, LMIRcam, that permits low-resolution (R~20) spectroscopy between 2.8 and 4.2 μm of every diffraction-limited resolution element in a 2.5"x2.5" field-of-view on a 2048x2048 HAWAII-2RG 5.2 μm-cutoff array. The 1" disk of Io, dotted with powerful self-luminous volcanic eruptions, provides an ideal target for ALES, where the single 8.4-meter aperture diffraction-limited scale for Io at opposition ranges from 240 kilometers (80 milliarcseconds) at 2.8 μm to 360 kilometers (120 milliarcseconds) at 4.2 μm. ALES provides the capability to assess the color temperature of each volcanic thermal emission site as well as map broadband absorbers such as SO2 frost. A monitoring campaign in the Spring 2017 semester provided two global snapshots of Io's volcanic activity with ALES as well as characterization of a new brightening episode at Loki Patera over four epochs between January and May 2017.

GOSAT/TANSO-FTS Measurement of Volcanic and Geothermal CO2 Emissions

NASA Astrophysics Data System (ADS)

Schwandner, Florian M.; Carn, Simon A.; Newhall, Christopher G.

2010-05-01

Approximately one tenth of the Earth's human population lives in direct reach of volcanic hazards. Being able to provide sufficiently early and scientifically sound warning is a key to volcanic hazard mitigation. Quantitative time-series monitoring of volcanic CO2 emissions will likely play a key role in such early warning activities in the future. Impending volcanic eruptions or any potentially disastrous activity that involves movement of magma in the subsurface, is often preceded by an early increase of CO2 emissions. Conventionally, volcanic CO2 monitoring is done either in campaigns of soil emission measurements (grid of one-time measuring points) that are labor intensive and slow, or by ground-based remote FTIR measurements in emission plumes. These methods are not easily available at all sites of potential activity and prohibitively costly to employ on a large number of volcanoes. In addition, both of these ground-based approaches pose a significant risk to the workers conducting these measurements. Some aircraft-based measurements have been conducted as well in the past, however these are limited by the usually meager funding situation of individual observatories, the hazard such flights pose to equipment and crew, and by the inaccessibility of parts of the plume due to ash hazards. The core motivation for this study is therefore to develop a method for volcanic CO2 monitoring from space that will provide sufficient coverage, resolution, and data quality for an application to quantitative time series monitoring and correlation with other available datasets, from a safe distance and with potentially global reach. In summary, the purpose of the proposed research is to quantify volcanic CO2 emissions using satellite-borne observations. Quantitative estimates will be useful for warning of impending volcanic eruptions, and assessing the contribution of volcanic CO2 to global GHG. Our approach encompasses method development and testing for the detection of

Deriving spatial patterns from a novel database of volcanic rock geochemistry in the Virunga Volcanic Province, East African Rift

NASA Astrophysics Data System (ADS)

Poppe, Sam; Barette, Florian; Smets, Benoît; Benbakkar, Mhammed; Kervyn, Matthieu

2016-04-01

The Virunga Volcanic Province (VVP) is situated within the western branch of the East-African Rift. The geochemistry and petrology of its' volcanic products has been studied extensively in a fragmented manner. They represent a unique collection of silica-undersaturated, ultra-alkaline and ultra-potassic compositions, displaying marked geochemical variations over the area occupied by the VVP. We present a novel spatially-explicit database of existing whole-rock geochemical analyses of the VVP volcanics, compiled from international publications, (post-)colonial scientific reports and PhD theses. In the database, a total of 703 geochemical analyses of whole-rock samples collected from the 1950s until recently have been characterised with a geographical location, eruption source location, analytical results and uncertainty estimates for each of these categories. Comparative box plots and Kruskal-Wallis H tests on subsets of analyses with contrasting ages or analytical methods suggest that the overall database accuracy is consistent. We demonstrate how statistical techniques such as Principal Component Analysis (PCA) and subsequent cluster analysis allow the identification of clusters of samples with similar major-element compositions. The spatial patterns represented by the contrasting clusters show that both the historically active volcanoes represent compositional clusters which can be identified based on their contrasted silica and alkali contents. Furthermore, two sample clusters are interpreted to represent the most primitive, deep magma source within the VVP, different from the shallow magma reservoirs that feed the eight dominant large volcanoes. The samples from these two clusters systematically originate from locations which 1. are distal compared to the eight large volcanoes and 2. mostly coincide with the surface expressions of rift faults or NE-SW-oriented inherited Precambrian structures which were reactivated during rifting. The lava from the Mugogo

The monogenetic Bayuda Volcanic Field, Sudan - New insights into geology and volcanic morphology

NASA Astrophysics Data System (ADS)

Lenhardt, Nils; Borah, Suranjana B.; Lenhardt, Sukanya Z.; Bumby, Adam J.; Ibinoof, Montasir A.; Salih, Salih A.

2018-05-01

The small monogenetic Bayuda Volcanic Field (BVF; 480 km2), comprising at least 53 cinder cones and 15 maar volcanoes in the Bayuda desert of northern Sudan is one of a few barely studied volcanic occurrences of Quaternary age in Sudan. The exact age of the BVF and the duration of volcanic activity has not yet been determined. Furthermore, not much is known about the eruptional mechanisms and the related magmatic and tectonic processes that led to the formation of the volcanic field. In the framework of a larger project focusing on these points it is the purpose of this contribution to provide a first account of the general geology of the BVF volcanoes as well as a first description of a general stratigraphy, including a first description of their morphological characteristics. This was done by means of fieldwork, including detailed rock descriptions, as well as the analysis of satellite images (SRTM dataset at 30 m spatial resolution). The BVF cinder cones are dominated by scoracious lapilli tephra units, emplaced mainly by pyroclastic fallout from Strombolian eruptions. Many cones are breached and are associated with lava flows. The subordinate phreatomagmatism represented by maar volcanoes suggests the presence of ground and/or shallow surface water during some of the eruptions. The deposits constituting the rims around the maar volcanoes are interpreted as having mostly formed due to pyroclastic surges. Many of the tephra rings around the maars are underlain by thick older lava flows. These are inferred to be the horizons where rising magma interacted with groundwater. The existence of phreatomagmatic deposits may point to a time of eruptive activity during a phase with wetter conditions and therefore higher groundwater levels than those encountered historically. This is supported by field observations as well as the morphological analysis, providing evidence for relatively high degrees of alteration of the BVF volcanoes and therefore older eruption ages as

The structural architecture of the Los Humeros volcanic complex and geothermal field, Trans-Mexican Volcanic Belt, Central Mexico

NASA Astrophysics Data System (ADS)

Norini, Gianluca; Groppelli, Gianluca; Sulpizio, Roberto; Carrasco Núñez, Gerardo; Davila Harris, Pablo

2014-05-01

The development of geothermal energy in Mexico is a very important goal, given the presence of a large heat anomaly, associated with the Trans-Mexican Volcanic Belt, the renewability of the resource and the low environmental impact. The Quaternary Los Humeros volcanic complex is an important geothermal target, whose evolution involved at least two caldera events, that alternated with other explosive and effusive activity. The first caldera forming event was the 460 ka eruption that produced the Xaltipan ignimbrite and formed a 15-20 km wide caldera. The second collapse event occurred 100 ka with the formation of the Zaragoza ignimbrite and a nested 8-10 km wide caldera. The whole volcano structure, the style of the collapses and the exact location of the calderas scarps and ring faults are still a matter of debate. The Los Humeros volcano hosts the productive Los Humeros Geothermal Field, with an installed capacity of 40 MW and additional 75 MW power plants under construction. Recent models of the geothermal reservoir predict the existence of at least two reservoirs in the geothermal system, separated by impermeable rock units. Hydraulic connectivity and hydrothermal fluids circulation occurs through faults and fractures, allowing deep steam to ascend while condensate flows descend. As a consequence, the plans for the exploration and exploitation of the geothermal reservoir have been based on the identification of the main channels for the circulation of hydrothermal fluids, constituted by faults, so that the full comprehension of the structural architecture of the caldera is crucial to improve the efficiency and minimize the costs of the geothermal field operation. In this study, we present an analysis of the Los Humeros volcanic complex focused on the Quaternary tectonic and volcanotectonics features, like fault scarps and aligned/elongated monogenetic volcanic centres. Morphostructural analysis and field mapping reveal the geometry, kinematics and dynamics of

California's Vulnerability to Volcanic Hazards: What's at Risk?

NASA Astrophysics Data System (ADS)

Mangan, M.; Wood, N. J.; Dinitz, L.

2015-12-01

California is a leader in comprehensive planning for devastating earthquakes, landslides, floods, and tsunamis. Far less attention, however, has focused on the potentially devastating impact of volcanic eruptions, despite the fact that they occur in the State about as frequently as the largest earthquakes on the San Andreas Fault Zone. At least 10 eruptions have occurred in the past 1,000 years—most recently in northern California (Lassen Peak 1914 to 1917)—and future volcanic eruptions are inevitable. The likelihood of renewed volcanism in California is about one in a few hundred to one in a few thousand annually. Eight young volcanoes, ranked as Moderate to Very High Threat [1] are dispersed throughout the State. Partially molten rock (magma) resides beneath at least seven of these—Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, and Salton Buttes— causing earthquakes, toxic gas emissions, hydrothermal activity, and (or) ground deformation. Understanding the hazards and identifying what is at risk are the first steps in building community resilience to volcanic disasters. This study, prepared in collaboration with the State of California Governor's Office of Emergency Management and the California Geological Survey, provides a broad perspective on the State's exposure to volcano hazards by integrating mapped volcano hazard zones with geospatial data on at-risk populations, infrastructure, and resources. The study reveals that ~ 16 million acres fall within California's volcano hazard zones, along with ~ 190 thousand permanent and 22 million transitory populations. Additionally, far-field disruption to key water delivery systems, agriculture, utilities, and air traffic is likely. Further site- and sector-specific analyses will lead to improved hazard mitigation efforts and more effective disaster response and recovery. [1] "Volcanic Threat and Monitoring Capabilities

Lidar detection of carbon dioxide in volcanic plumes

NASA Astrophysics Data System (ADS)

Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Maio, Giovanni; Del Franco, Mario; Aiuppa, Alessandro

2015-06-01

Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. Two differential absorption lidar instruments will be presented in this paper: BILLI (BrIdge voLcanic LIdar), based on injection seeded Nd:YAG laser, double grating dye laser, difference frequency mixing (DFM) and optical parametric amplifier (OPA), and VULLI (VULcamed Lidar), based on injection seeded Nd:YAG laser and optical parametric oscillator (OPO). The first one is funded by the ERC (European Research Council) project BRIDGE and the second one by the ERDF (European Regional Development Fund) project VULCAMED. While VULLI has not yet been tested in a volcanic site, BILLI scanned the gas emitted by Pozzuoli Solfatara (Campi Flegrei volcanic area, Naples, Italy) during a field campaign carried out from 13 to 17 October 2014. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater area. Lidar measurements were in good agreement with well-established techniques, based on different operating principles. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar, representing the first direct measurement of this kind ever performed on an active volcano and showing the high potential of laser remote sensing in geophysical research.

Volcanic deformation in the Andes

NASA Astrophysics Data System (ADS)

Riddick, S.; Fournier, T.; Pritchard, M.

2009-05-01

We present the results from an InSAR survey of volcanic activity in South America. We use data from the Japanese Space Agency's ALOS L-band radar satellite from 2006-2009. The L-band instrument provides better coherence in densely vegetated regions, compared to the shorter wave length C-band data. The survey reveals volcano related deformation in regions, north, central and southern, of the Andes volcanic arc. Since observations are limited to the austral summer, comprehensive coverage of all volcanoes is not possible. Yet, our combined observations reveal volcanic/hydrothermal deformation at Lonquimay, Llaima, Laguna del Maule, and Chaitén volcanoes, extend deformation measurements at Copahue, and illustrate temporal complexity to the previously described deformation at Cerro Hudson and Cordón Caulle. No precursory deformation is apparent before the large Chaitén eruption (VEI_5) of 2 May 2008, (at least before 16 April) suggesting rapid magma movement from depth at this long dormant volcano. Subsidence at Ticsani Volcano occurred coincident with an earthquake swarm in the same region.

The "Youngest" Illinoisans: A Statistical Look at Infants and Toddlers in Illinois. Publication #2013-53

ERIC Educational Resources Information Center

Murphey, David; Cooper, Mae; Forry, Nicole

2014-01-01

Illinois' youngest children--nearly half-a-million infants and toddlers--are at the leading edge of a demographic transformation. They herald a state, and a nation, more diverse with respect to race/ethnicity, country of origin, language, and family type than at any time in recent history. Yet, this is a generation notable for marked inequities,…

Io's Diverse Styles of Volcanic Activity: Results from Galileo NIMS

NASA Technical Reports Server (NTRS)

Lopes, R. M. C.; Smythe, W. D.; Kamp, L. W.; Doute, S.; Carlson, R.; McEwen, A.; Geissler, P.

2001-01-01

Observations by Galileo's Near-Infrared Mapping Spectrometer were used to map the thermal structure of several of Io's hot spots, revealing different styles of volcanism Additional information is contained in the original extended abstract..

Are Parental Welfare Work Requirements Good for Disadvantaged Children? Evidence from Age-of-Youngest-Child Exemptions

ERIC Educational Resources Information Center

Herbst, Chris M.

2017-01-01

This paper assesses the impact of welfare reform's parental work requirements on low-income children's cognitive and social-emotional development. The identification strategy exploits an important feature of the work requirement rules--namely, age-of-youngest-child exemptions--as a source of quasi-experimental variation in first-year maternal…

A multi-data stream assimilation framework for the assessment of volcanic unrest

NASA Astrophysics Data System (ADS)

Gregg, Patricia M.; Pettijohn, J. Cory

2016-01-01

Active volcanoes pose a constant risk to populations living in their vicinity. Significant effort has been spent to increase monitoring and data collection campaigns to mitigate potential volcano disasters. To utilize these datasets to their fullest extent, a new generation of model-data fusion techniques is required that combine multiple, disparate observations of volcanic activity with cutting-edge modeling techniques to provide efficient assessment of volcanic unrest. The purpose of this paper is to develop a data assimilation framework for volcano applications. Specifically, the Ensemble Kalman Filter (EnKF) is adapted to assimilate GPS and InSAR data into viscoelastic, time-forward, finite element models of an evolving magma system to provide model forecasts and error estimations. Since the goal of this investigation is to provide a methodological framework, our efforts are focused on theoretical development and synthetic tests to illustrate the effectiveness of the EnKF and its applicability in physical volcanology. The synthetic tests provide two critical results: (1) a proof of concept for using the EnKF for multi dataset assimilation in investigations of volcanic activity; and (2) the comparison of spatially limited, but temporally dense, GPS data with temporally limited InSAR observations for evaluating magma chamber dynamics during periods of volcanic unrest. Results indicate that the temporally dense information provided by GPS observations results in faster convergence and more accurate model predictions. However, most importantly, the synthetic tests illustrate that the EnKF is able to swiftly respond to data updates by changing the model forecast trajectory to match incoming observations. The synthetic results demonstrate a great potential for utilizing the EnKF model-data fusion method to assess volcanic unrest and provide model forecasts. The development of these new techniques provides: (1) a framework for future applications of rapid data

Volcanic Forcing of Global Warming during the Pleistocene?

NASA Astrophysics Data System (ADS)

Ericson, J. E.

2002-12-01

The volcanic forcing hypothesis is a new model of global climatic change that may have significance for the history of the Earth and palaeoclimate. The rapid injection of CO2 into the atmosphere during volcanic eruption through underlying massive carbonate appears to trigger global warming through the emission of this greenhouse gas. The record of eruptions (10-20 Kya) of 6 volcanoes overlying 900-10,000 meters of carbonate of the Cordillerian geosyncline in the American Southwest is synchronous with the Late Pleistocene marine transgression record. The record of volcanic eruptions through massive carbonates (20-71 Kya) in Italy, Indonesia and the American Southwest appears to be synchronous with the Wisconsin interstadial events. The extension of the volcanic eruption and climatic records to 71 Kya and inclusion of other volcanic regions represents additional supporting of evidence of the volcanic forcing hypothesis. As an example of these processes, the thermal dissociation of carbonate by magma forming a volcanic conduit (0.4 km high, 0.5 km radius) and subsequent release of carbon dioxide would increase the atmospheric carbon dioxide by 25%. The emitted CO2 would trigger a series of other processes, ocean-atmospheric CO2 exchange, increased photosynthesis and changes with terrestrial biome and global warming. [Recent field reconnaissance of Sunset Crater (erupted 1064-65 AD) indicates the evidence for thermal dissolution of limestone during basaltic extrusion.] Carbon dioxide emitted from volcanic-carbonate sources meets several observed conditions: a rapid increase (<20 years) in atmospheric carbon dioxide, abrupt increases of marine (isotopic) carbon, dilution of atmospheric radiocarbon activity independent of fluctuations of the geomagnetic field and cosmic ray fluxes, temporal covariation of sulfate, Ca+2, and CO2 in ice core records and random, interstadial events during glaciation. Volcanic forcing hypothesis represents a new model and synthesis of

Role of social media and networking in volcanic crises and communication

USGS Publications Warehouse

Sennert, Sally K.; Klemetti, Erik W.; Bird, Deanne

2017-01-01

The growth of social media as a primary and often preferred news source has contributed to the rapid dissemination of information about volcanic eruptions and potential volcanic crises as an eruption begins. Information about volcanic activity comes from a variety of sources: news organisations, emergency management personnel, individuals (both public and official) and volcano monitoring agencies. Once posted, this information is easily shared, increasing the reach to a much broader population than the original audience. The onset and popularity of social media as a vehicle for eruption information dissemination has presented many benefits as well as challenges, and points towards a need for a more unified system for information. This includes volcano observatories using social media as an official channels to distribute activity statements, forecasts and predictions on social media, in addition to the archiving of images and data activity. This chapter looks at two examples of projects that collect / disseminate information regarding volcanic crises and eruptive activity utilizing social media sources. Based on those examples, recommendations are made to volcanic observatories in relation to the use of social media as a two-way communication tool. These recommendations include: using social media as a two-way dialogue to communicate and receive information directly from the public and other sources; stating that the social media account is from an official source; and, posting types of information that the public are seeking such as images, videos and figures.

Automated Identification of Volcanic Plumes using the Ozone Monitoring Instrument (OMI)

NASA Astrophysics Data System (ADS)

Flower, V. J. B.; Oommen, T.; Carn, S. A.

2015-12-01

Volcanic eruptions are a global phenomenon which are increasingly impacting human populations due to factors such as the extension of population centres into areas of higher risk, expansion of agricultural sectors to accommodate increased production or the increasing impact of volcanic plumes on air travel. In areas where extensive monitoring is present these impacts can be moderated by ground based monitoring and alert systems, however many volcanoes have little or no monitoring capabilities. In many of these regions volcanic alerts are generated by local communities with limited resources or formal communication systems, however additional eruption alerts can result from chance encounters with passing aircraft. In contrast satellite based remote sensing instruments possess the capability to provide near global daily monitoring, facilitating automated volcanic eruption detection. One such system generates eruption alerts through the detection of thermal anomalies, known as MODVOLC, and is currently operational utilising moderate resolution MODIS satellite data. Within this work we outline a method to distinguish SO2 eruptions from background levels recorded by the Ozone Monitoring Instrument (OMI) through the identification and classification of volcanic activity over a 5 year period. The incorporation of this data into a logistic regression model facilitated the classification of volcanic events with an overall accuracy of 80% whilst consistently identifying plumes with a mass of 400 tons or higher. The implementation of the developed model could facilitate the near real time identification of new and ongoing volcanic activity on a global scale.

Identifying the Linkages Between Microbial Activity and Gas Flux of Subaerial Volcanic Environments: A Guide to Exploring Magmatic Planets and Moons

NASA Astrophysics Data System (ADS)

Miller, H. A.; Lopez, T. M.; Fischer, T. P.; Schrenk, M. O.

2017-11-01

Promising contemporary analogs of habitable environments are fumaroles associated with active volcanism. Experimental studies linking sediments, microbes, and volatile outgassing may lead to new bio- or geosignatures of habitability.

New geochemical insights into volcanic degassing.

PubMed

Edmonds, Marie

2008-12-28

Magma degassing plays a fundamental role in controlling the style of volcanic eruptions. Whether a volcanic eruption is explosive, or effusive, is of crucial importance to approximately 500 million people living in the shadow of hazardous volcanoes worldwide. Studies of how gases exsolve and separate from magma prior to and during eruptions have been given new impetus by the emergence of more accurate and automated methods to measure volatile species both as volcanic gases and dissolved in the glasses of erupted products. The composition of volcanic gases is dependent on a number of factors, the most important being magma composition and the depth of gas-melt segregation prior to eruption; this latter parameter has proved difficult to constrain in the past, yet is arguably the most critical for controlling eruptive style. Spectroscopic techniques operating in the infrared have proved to be of great value in measuring the composition of gases at high temporal resolution. Such methods, when used in tandem with microanalytical geochemical investigations of erupted products, are leading to better constraints on the depth at which gases are generated and separated from magma. A number of recent studies have focused on transitions between explosive and effusive activity and have led to a better understanding of gas-melt segregation at basaltic volcanoes. Other studies have focused on degassing during intermediate and silicic eruptions. Important new results include the recognition of fluxing by deep-derived gases, which buffer the amount of dissolved volatiles in the melt at shallow depths, and the observation of gas flow up permeable conduit wall shear zones, which may be the primary mechanism for gas loss at the cusp of the most explosive and unpredictable volcanic eruptions. In this paper, I review current and future directions in the field of geochemical studies of volcanic degassing processes and illustrate how the new insights are beginning to change the way in

Relationship between subsidence and volcanic load, Hawaii

USGS Publications Warehouse

Moore, J.G.

1970-01-01

A computer analysis of tide-gage records in the northeast Pacific indicates that the active volcanic islands of eastern Hawaii are subsiding at a rate considerably faster than the eustatic rise of sea level. The rate of absolute subsidence increases progressively toward the center of current activity on the Island of Hawaii. Honolulu, Oahu, appears to be stable; Kahului, Maui, is subsiding at 1.7 mm per year; and Hilo, Hawaii, is subsiding at 4.8 mm per year. This subsidence is apparently related to downbowing of the crust throughout a zone 400 km in diameter by the weight of volcanic material added to the crust by active volcanoes, principally Mauna Loa and Kilauea on the Island of Hawaii. The Hawaiian Arch encircles the subsiding zone and may be uplifted by material moving down and outward from the zone of subsidence. The annual volume of subsidence is about 270??106 m3, whereas the average annual volume of erupted basalt on the Island of Hawaii (based on historic records back to about 1820) is about 50??106 m3. The great excess of subsidence over volcanic addition cannot be reconciled by isostatic models, and is apparently the result of other processes operating in the volcano and its basement thet are poorly understood. Probably the more important of these processes are intrusions and submarine volcanism, both of which are providing additional unseen load on the volcanoes. Furthermore, the rate of eruption may be uplifted by material moving down and outward from the zone of subsidence may be overestimated due to localized downslope movement of the margins of the islands. ?? 1970 Stabilimento Tipografico Francesco Giannini & Figli.

Global volcanic aerosol properties derived from emissions, 1990-2015, using CESM1(WACCM)

NASA Astrophysics Data System (ADS)

Mills, Michael; Schmidt, Anja; Easter, Richard; Solomon, Susan; Kinnison, Douglas; Ghan, Steven; Neely, Ryan; Marsh, Daniel; Conley, Andrew; Bardeen, Charles; Gettelman, Andrew

2016-04-01

Accurate representation of global stratospheric aerosols from volcanic and non-volcanic sulfur emissions is key to understanding the cooling effects and ozone-losses that may be linked to volcanic activity. Attribution of climate variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the rate of global average temperature increases. We have compiled a database of volcanic SO2 emissions and plume altitudes for eruptions from 1990 to 2015, and developed a new prognostic capability for simulating stratospheric sulfate aerosols in the Community Earth System Model (CESM). We combined these with other non-volcanic emissions of sulfur sources to reconstruct global aerosol properties from 1990 to 2015. Our calculations show remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD), and with in situ measurements of stratospheric aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD calculations represent a clear improvement over available satellite-based analyses, which generally ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at mid- and high-latitudes. Our SAD calculations greatly improve on that provided for the Chemistry-Climate Model Initiative, which misses about 60% of the SAD measured in situ on average during both volcanically active and volcanically quiescent periods. The stark differences in SAOD and SAD compared to other data sets will have significant effects on calculations of the radiative forcing of climate and global stratospheric chemistry over the period 2005-2015. In light of these results, the impact of volcanic aerosols in reducing the rate of global average temperature increases since the year 2000 should be revisited. We have made our calculated aerosol properties from January 1990 to

Volcanic Centers in the East Africa Rift: Volcanic Processes with Seismic Stresses to Identify Potential Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Patlan, E.; Wamalwa, A. M.; Kaip, G.; Velasco, A. A.

2015-12-01

The Geothermal Development Company (GDC) in Kenya actively seeks to produce geothermal energy, which lies within the East African Rift System (EARS). The EARS, an active continental rift zone, appears to be a developing tectonic plate boundary and thus, has a number of active as well as dormant volcanoes throughout its extent. These volcanic centers can be used as potential sources for geothermal energy. The University of Texas at El Paso (UTEP) and the GDC deployed seismic sensors to monitor several volcanic centers: Menengai, Silali, and Paka, and Korosi. We identify microseismic, local events, and tilt like events using automatic detection algorithms and manual review to identify potential local earthquakes within our seismic network. We then perform the double-difference location method of local magnitude less than two to image the boundary of the magma chamber and the conduit feeding the volcanoes. In the process of locating local seismicity, we also identify long-period, explosion, and tremor signals that we interpret as magma passing through conduits of the magma chamber and/or fluid being transported as a function of magma movement or hydrothermal activity. We used waveform inversion and S-wave shear wave splitting to approximate the orientation of the local stresses from the vent or fissure-like conduit of the volcano. The microseismic events and long period events will help us interpret the activity of the volcanoes. Our goal is to investigate basement structures beneath the volcanoes and identify the extent of magmatic modifications of the crust. Overall, these seismic techniques will help us understand magma movement and volcanic processes in the region.

Late Pleistocene-Holocene volcanic activity in northern Victoria Land recorded in Ross Sea (Antarctica) marine sediments

NASA Astrophysics Data System (ADS)

Del Carlo, P.; Di Roberto, A.; Di Vincenzo, G.; Bertagnini, A.; Landi, P.; Pompilio, M.; Colizza, E.; Giordano, G.

2015-05-01

Eight pyroclastic fall deposits have been identified in cores of Late Pleistocene-Holocene marine sediments from the Ross Sea (Antarctica), and their components, granulometry and clast morphologies were analysed. Sedimentological, petrographic and geochemical analysis of clasts, with 40Ar-39Ar dating of alkali feldspar grains, indicate that during this period at least five explosive eruptions of mid to high intensity (plinian to subplinian) occurred, and that three of these eruptions took place from Mount Melbourne volcanic complex, between 137.1 ± 3.4 and 12 ka. Geochemical comparison of the studied tephra with micro- and crypto-tephra recovered from deep Antarctic ice cores and from nearby englacial tephra at Frontier Mountain indicates that eruptive activity in the Melbourne Volcanic Province of northern Victoria Land was intense during the Late Pleistocene-Holocene, but only a general area of provenance for the majority of the identified tephra can be identified.

Volcanic influence on centennial to millennial Holocene Greenland temperature change.

PubMed

Kobashi, Takuro; Menviel, Laurie; Jeltsch-Thömmes, Aurich; Vinther, Bo M; Box, Jason E; Muscheler, Raimund; Nakaegawa, Toshiyuki; Pfister, Patrik L; Döring, Michael; Leuenberger, Markus; Wanner, Heinz; Ohmura, Atsumu

2017-05-03

Solar variability has been hypothesized to be a major driver of North Atlantic millennial-scale climate variations through the Holocene along with orbitally induced insolation change. However, another important climate driver, volcanic forcing has generally been underestimated prior to the past 2,500 years partly owing to the lack of proper proxy temperature records. Here, we reconstruct seasonally unbiased and physically constrained Greenland Summit temperatures over the Holocene using argon and nitrogen isotopes within trapped air in a Greenland ice core (GISP2). We show that a series of volcanic eruptions through the Holocene played an important role in driving centennial to millennial-scale temperature changes in Greenland. The reconstructed Greenland temperature exhibits significant millennial correlations with K + and Na + ions in the GISP2 ice core (proxies for atmospheric circulation patterns), and δ 18 O of Oman and Chinese Dongge cave stalagmites (proxies for monsoon activity), indicating that the reconstructed temperature contains hemispheric signals. Climate model simulations forced with the volcanic forcing further suggest that a series of large volcanic eruptions induced hemispheric-wide centennial to millennial-scale variability through ocean/sea-ice feedbacks. Therefore, we conclude that volcanic activity played a critical role in driving centennial to millennial-scale Holocene temperature variability in Greenland and likely beyond.

Rhyolite thermobarometry and the shallowing of the magma reservoir, Coso volcanic field, California

USGS Publications Warehouse

Manley, C.R.; Bacon, C.R.

2000-01-01

The compositionally bimodal Pleistocene Coso volcanic field is located at the western margin of the Basin and Range province ~ 60 km north of the Garlock fault. Thirty-nine nearly aphyric high-silica rhyolite domes were emplaced in the past million years: one at 1 Ma from a transient magma reservoir, one at ~ 0.6 Ma, and the rest since ~ 0.3 Ma. Over the past 0.6 My, the depth from which the rhyolites erupted has decreased and their temperatures have become slightly higher. Pre-eruptive conditions of the rhyolite magmas, calculated from phenocryst compositions using the two-oxide thermometer and the Al-in-hornblende barometer, ranged from 740??C and 270 MPa (2.7 kbar; ~ 10 km depth) for the ~ 0.6 Ma magma, to 770??C and 140 MPa (1.4 kbar; ~ 5.5 km) for the youngest (~ 0.04 Ma) magma. Results are consistent with either a single rhyolitic reservoir moving upward through the crust, or a series of successively shallower reservoirs. As the reservoir has become closer to the surface, eruptions have become both more frequent and more voluminous.

Volcanic unrest and hazard communication in Long Valley Volcanic Region, California

USGS Publications Warehouse

Hill, David P.; Mangan, Margaret T.; McNutt, Stephen R.

2017-01-01

The onset of volcanic unrest in Long Valley Caldera, California, in 1980 and the subsequent fluctuations in unrest levels through May 2016 illustrate: (1) the evolving relations between scientists monitoring the unrest and studying the underlying tectonic/magmatic processes and their implications for geologic hazards, and (2) the challenges in communicating the significance of the hazards to the public and civil authorities in a mountain resort setting. Circumstances special to this case include (1) the sensitivity of an isolated resort area to media hype of potential high-impact volcanic and earthquake hazards and its impact on potential recreational visitors and the local economy, (2) a small permanent population (~8000), which facilitates face-to-face communication between scientists monitoring the hazard, civil authorities, and the public, and (3) the relatively frequent turnover of people in positions of civil authority, which requires a continuing education effort on the nature of caldera unrest and related hazards. Because of delays associated with communication protocols between the State and Federal governments during the onset of unrest, local civil authorities and the public first learned that the U.S. Geological Survey was about to release a notice of potential volcanic hazards associated with earthquake activity and 25-cm uplift of the resurgent dome in the center of the caldera through an article in the Los Angeles Times published in May 1982. The immediate reaction was outrage and denial. Gradual acceptance that the hazard was real required over a decade of frequent meetings between scientists and civil authorities together with public presentations underscored by frequently felt earthquakes and the onset of magmatic CO2 emissions in 1990 following a 11-month long earthquake swarm beneath Mammoth Mountain on the southwest rim of the caldera. Four fatalities, one on 24 May 1998 and three on 6 April 2006, underscored the hazard posed by the CO2�

Volcanic Gas Emissions Mapping Using a Mass Spectrometer System

NASA Technical Reports Server (NTRS)

Griffin, Timothy P.; Diaz, J. Andres

2008-01-01

The visualization of hazardous gaseous emissions at volcanoes using in-situ mass spectrometry (MS) is a key step towards a better comprehension of the geophysical phenomena surrounding eruptive activity. In-Situ gas data consisting of helium, carbon dioxide, sulfur dioxide, and other gas species, were acquired with an MS system. MS and global position system (GPS) data were plotted on ground imagery, topography, and remote sensing data collected by a host of instruments during the second Costa Rica Airborne Research and Technology Applications (CARTA) mission This combination of gas and imaging data allowed 3-dimensional (3-D) visualization of the volcanic plume end the mapping of gas concentration at several volcanic structures and urban areas This combined set of data has demonstrated a better tool to assess hazardous conditions by visualizing and modeling of possible scenarios of volcanic activity. The MS system is used for in-situ measurement of three-dimensional gas concentrations at different volcanic locations with three different transportation platforms, aircraft, auto, and hand carried. The demonstration for urban contamination mapping is also presented as another possible use for the MS system.

Seismically active column and volcanic plumbing system beneath the island arc of the Izu-Bonin subduction zone

NASA Astrophysics Data System (ADS)

Špičák, Aleš; Vaněk, Jiří; Hanuš, Václav

2009-12-01

A detailed spatio-temporal analysis of teleseismic earthquake occurrence (mb > 4.0) along the convergent margin of the Izu-Bonin-Mariana arc system reveals an anomalously high concentration of events between 27° and 30.5°N, beneath a chain of seamounts between Tori-shima and Nishino-shima volcanoes. This seismicity is dominated by the 1985/1986 earthquake swarm represented in the Engdahl—van der Hilst—Buland database by 146 earthquakes in the body wave magnitude range 4.3-5.8 and focal depth range 1-100 km. The epicentral cluster of the swarm is elongated parallel to the volcanic chain. Available focal mechanisms are consistent with an extensional tectonic regime and reveal nodal planes with azimuths close to that of the epicentral cluster. Earthquakes of the 1985/1986 swarm occurred in seven time phases. Seismic activity migrated in space from one phase to the other. Earthquake foci belonging to individual phases of the swarm aligned in vertically disposed seismically active columns. The epicentral zones of the columns are located in the immediate vicinity of seamounts Suiyo and Mokuyo, recently reported by the Japanese Meteorological Agency as volcanically active. The three observations—episodic character of earthquake occurrence, column-like vertically arranged seismicity pattern, and existence of volcanic seamounts at the seafloor above the earthquake foci—led us to interpret the 1985/1986 swarm as a consequence of subduction-related magmatic and/or fluid activity. A modification of the shallow earthquake swarm magmatic model of D. Hill fits earthquake foci distribution, tectonic stress orientation and fault plane solutions. The 1985/1986 deep-rooted earthquake swarm in the Izu-Bonin region represents an uncommon phenomenon of plate tectonics. The portion of the lithospheric wedge that was affected by the swarm should be composed of fractured rigid, brittle material so that the source of magma and/or fluids which might induce the swarm should be

Seismically active column and volcanic plumbing system beneath the island arc of the Izu-Bonin subduction zone

NASA Astrophysics Data System (ADS)

Špičák, Aleš; Vaněk, Jiří; Hanuš, Václav

2009-12-01

A detailed spatio-temporal analysis of teleseismic earthquake occurrence (mb > 4.0) along the convergent margin of the Izu-Bonin-Mariana arc system reveals an anomalously high concentration of events between 27° and 30.5°N, beneath a chain of seamounts between Tori-shima and Nishino-shima volcanoes. This seismicity is dominated by the 1985/1986 earthquake swarm represented in the Engdahl-van der Hilst-Buland database by 146 earthquakes in the body wave magnitude range 4.3-5.8 and focal depth range 1-100 km. The epicentral cluster of the swarm is elongated parallel to the volcanic chain. Available focal mechanisms are consistent with an extensional tectonic regime and reveal nodal planes with azimuths close to that of the epicentral cluster. Earthquakes of the 1985/1986 swarm occurred in seven time phases. Seismic activity migrated in space from one phase to the other. Earthquake foci belonging to individual phases of the swarm aligned in vertically disposed seismically active columns. The epicentral zones of the columns are located in the immediate vicinity of seamounts Suiyo and Mokuyo, recently reported by the Japanese Meteorological Agency as volcanically active. The three observations-episodic character of earthquake occurrence, column-like vertically arranged seismicity pattern, and existence of volcanic seamounts at the seafloor above the earthquake foci-led us to interpret the 1985/1986 swarm as a consequence of subduction-related magmatic and/or fluid activity. A modification of the shallow earthquake swarm magmatic model of D. Hill fits earthquake foci distribution, tectonic stress orientation and fault plane solutions. The 1985/1986 deep-rooted earthquake swarm in the Izu-Bonin region represents an uncommon phenomenon of plate tectonics. The portion of the lithospheric wedge that was affected by the swarm should be composed of fractured rigid, brittle material so that the source of magma and/or fluids which might induce the swarm should be situated at a

Validation of Volcanic Ash Forecasting Performed by the Washington Volcanic Ash Advisory Center

NASA Astrophysics Data System (ADS)

Salemi, A.; Hanna, J.

2009-12-01

In support of NOAA’s mission to protect life and property, the Satellite Analysis Branch (SAB) uses satellite imagery to monitor volcanic eruptions and track volcanic ash. The Washington Volcanic Ash Advisory Center (VAAC) was established in late 1997 through an agreement with the International Civil Aviation Organization (ICAO). A volcanic ash advisory (VAA) is issued every 6 hours while an eruption is occurring. Information about the current location and height of the volcanic ash as well as any pertinent meteorological information is contained within the VAA. In addition, when ash is detected in satellite imagery, 6-, 12- and 18-hour forecasts of ash height and location are provided. This information is garnered from many sources including Meteorological Watch Offices (MWOs), pilot reports (PIREPs), model forecast winds, radiosondes and volcano observatories. The Washington VAAC has performed a validation of their 6, 12 and 18 hour airborne volcanic ash forecasts issued since October, 2007. The volcanic ash forecasts are viewed dichotomously (yes/no) with the frequency of yes and no events placed into a contingency table. A large variety of categorical statistics useful in describing forecast performance are then computed from the resulting contingency table.

A volcanic wind-stress origin of the Atlantic Multidecadal Oscillation

NASA Astrophysics Data System (ADS)

Birkel, S. D.; Mayewski, P. A.; Maasch, K. A.; Auger, J.; Lyon, B.

2016-12-01

The Atlantic Multidecadal Oscillation (AMO) is a mode of sea-surface temperature (SST) variability in the North Atlantic that has significant impact on global climate. Most previous studies ascribe the origin of the AMO to oceanic mechanisms, and suggest only a limited role for the atmosphere. Here, we suggest that the AMO is manifested from basin-wide changes in surface wind stress that arise in response to episodic volcanic activity. Our interpretation is based on historical SST, reanalysis, and stratospheric aerosol optical thickness data, wherein it is evident that cool (warm) intervals of the AMO coincide with emergence of strong (weak) winds and high (low) volcanic activity. We find that SST excursions ultimately develop from atmospheric forcing as volcanic events project onto the North Atlantic Oscillation (NAO). A volcanic signature is particularly evident beneath the westerlies in the subpolar region south of Greenland, where several large SST excursions occur coincident with identifiable major eruptions. High latitude surface waters cool when NAO+ circulation, which includes a deepened Icelandic Low, draws cold flow out of the Labrador Sea and into the subpolar region. Important feedbacks that cause SST anomalies to spread across the basin include cloud cover, wind-driven upwelling, and entrainment of Saharan dust into the tropical easterlies. Finally, we speculate that cooling in the North Atlantic observed since 2011 could be linked to renewed volcanic activity over Iceland, namely from the eruptions of Grímsvötn (2011) and Bárðarbunga (2014). An important question remains how North Atlantic SST variability will evolve as atmospheric circulation becomes increasingly modified by human activity.

Potential Future Igneous Activity at Yucca Mountain, Nevada

NASA Astrophysics Data System (ADS)

Cline, M.; Perry, F. V.; Valentine, G. A.; Smistad, E.

2005-12-01

Location, timing, and volumes of post-Miocene volcanic activity, along with expert judgement, provide the basis for assessing the probability of future volcanism intersecting a proposed repository for nuclear waste at Yucca Mountain, Nevada. Analog studies of eruptive centers in the region that may represent the style and extent of possible future igneous activity at Yucca Mountain have aided in defining the consequence scenarios for intrusion into and eruption through a proposed repository. Modeling of magmatic processes related to magma/proposed repository interactions has been used to assess the potential consequences of a future igneous event through a proposed repository at Yucca Mountain. Results of work to date indicate future igneous activity in the Yucca Mountain region has a very low probability of intersecting the proposed repository. Probability of a future event intersecting a proposed repository at Yucca Mountain is approximately 1.7 X 10-8 per year. Since completion of the Probabilistic Volcanic Hazard Assessment (PVHA) in 1996, anomalies representing potential buried volcanic centers have been identified from aeromagnetic surveys. A re-assessment of the hazard is currently underway to evaluate the probability of intersection in light of new information and to estimate the probability of one or more volcanic conduits located in the proposed repository along a dike that intersects the proposed repository. U.S. Nuclear Regulatory Commission regulations for siting and licensing a proposed repository require that the consequences of a disruptive event (igneous event) with annual probability greater than 1 X 10-8 be evaluated. Two consequence scenarios are considered; 1) igneous intrusion-groundwater transport case and 2) volcanic eruptive case. These scenarios equate to a dike or dike swarm intersecting repository drifts containing waste packages, formation of a conduit leading to a volcanic eruption through the repository that carries the contents of

Map of Io Volcanic Heat Flow

NASA Image and Video Library

2015-09-15

This frame from an animation shows Jupiter volcanic moon Io as seen by NASA Voyager and Galileo spacecraft (at left) and the pattern of heat flow from 242 active volcanoes (at right). The red and yellow areas are places where local heat flow is greatest -- the result of magma erupting from Io's molten interior onto the surface. The map is the result of analyzing decades of observations from spacecraft and ground-based telescopes. It shows Io's usual volcanic thermal emission, excluding the occasional massive but transient "outburst" eruption; in other words, this is what Io looks like most of the time. This heat flow map will be used to test models of interior heating. The map shows that areas of enhanced volcanic heat flow are not necessarily correlated with the number of volcanoes in a particular region and are poorly correlated with expected patterns of heat flow from current models of tidal heating -- something that is yet to be explained. This research is published in association with a 2015 paper in the journal Icarus by A. Davies et al., titled "Map of Io's Volcanic Heat Flow," (http://dx.doi.org/10.1016/j.icarus.2015.08.003.) http://photojournal.jpl.nasa.gov/catalog/PIA19655

Deccan volcanism at the Cretaceous-Tertiary boundary

NASA Technical Reports Server (NTRS)

Courtillot, V.; Vandamme, D.; Besse, J.

1988-01-01

The accuracy with which one can claim that Deccan trap volcanism occurred at the Cretaceous-Tertiary boundary (KTB) over a very short time interval is of key importance in deciding whether a volcanic origin of the KTB events should be taken seriously. In the two years since paleomagnetic, paleontological and geodynamic evidence was published, further data have become available and the case now appears to be well constrained. The Ar-40/Ar-39 results from six labs have yielded some 24 reliable plateau ages that narrow the age range to 65 to 69 Ma. Moreover, it appears that a significant part of this range results from inter-lab spread and possible minor alteration. Paleontology demonstrates that volcanism started in the Maestrichtian, more precisely in the A. mayaroensis zone. Paleomagnetism shows that volcanism spanned only 3 chrons and only one correlation remains possible, that of the main central reversed chron with 29R. Therefore, whereas Ar-40/Ar-39 is able only to restrict the duration of volcanism to some 4 Ma, paleomagnetism restricts it to 0.5 Ma. Using some geochemical indicators such as C-13 as proxy, it is suggested that volcanism actually consists of a few shorter events of unequal magnitude. Extrusion rates may be as high as 100 cu km/yr and fissure lengths as long as several 100 km. Such a scenario appears to be at least as successful as others in accounting for most anomalies observed at the KTB. Particularly important are Iridium and other platinum group elements (PGE) profiles, Sr-87/Sr-86, C-13, 0-18, other exotic geochemical signatures, spherules, soot, shocked minerals, selective and stepwise extinctions. The environmental impact of CO2 possibly released during explosive phases of volcanism, and SO2 released during effusive phases, and the ability of volcanism to ensure worldwide distribution of KTB products are now all addressed. In conclusion, the case for a causal link between internal hotspot activity, birth of the Reunion hotspot itself as

Extensive hydrothermal activity in the NE Lau basin revealed by ROV dives

NASA Astrophysics Data System (ADS)

Embley, R. W.; Resing, J. A.; Tebo, B.; Baker, E. T.; Butterfield, D. A.; Chadwick, B.; Davis, R.; de Ronde, C. E. J.; Lilley, M. D.; Lupton, J. E.; Merle, S. G.; Rubin, K. H.; Shank, T. M.; Walker, S. L.; Arculus, R. J.; Bobbitt, A. M.; Buck, N. J.; Caratori Tontini, F.; Crowhurst, P. V.; Mitchell, E.; Olson, E. J.; Ratmeyer, V.; Richards, S.; Roe, K. K.; Kenner-Chavis, P.; Martinez-Lyons, A.; Sheehan, C.; Brian, R.

2014-12-01

Dives with the QUEST 4000 ROV (Remotely Operated Vehicle) in September 2012 discovered nine hydrothermal sites in the arc and rear-arc region of the NE Lau Basin in 1150 m to 2630 m depth. These sites, originally detected by water column and seafloor surveys conducted in 2008-2011, include: (1) a paired sulfur-rich/black smoker field on the summit of a tectonically deformed magmatic arc volcano (Niua), (2) fracture-controlled black smoker venting on several small en echelon seamounts (north Matas) that lie between the magmatic arc and the backarc spreading center and (3) a magmatic degassing site on the summit of a dacite cone within a large (~12 km diameter) caldera volcano (Niuatahi). Dives at West Mata Seamount, which was undergoing strombolian volcanic activity and effusive rift-zone eruptions from 2008 to 2010, revealed a dormant volcanic phase in September 2012, with continued low-temperature diffuse venting. The high-temperature venting is likely driven by magmatic heat indicative of underlying partial melt zones and/or melt pockets distributed through the region. The occurrence of the youngest known boninite eruptions on the Mata volcanoes is consistent with subduction fluid flux melting extending into the rear-arc zone. Extension related to the transition from subduction to strike-slip motion of the northern Tonga Arc over the active Subduction-Transform Edge Propagator (STEP) fault probably contributes to the enhanced volcanism/hydrothermal activity in the NE Lau Basin. Chemosynthetic ecosystems at these sites range from mostly motile, lower diversity ecosystems at the eruptive/magmatically-degassing sites to higher diversity ecosystems with less mobile faunal components at the black-smoker systems. The wide range of fluid chemistry, water depth and geologic settings of the hydrothermal systems in this area provides an intriguing template to study the interaction of hydrothermal fluid chemistry, chemosynthetic habitats and their geologic underpinning

Hyperactive hydrothermal activity in the NE Lau basin revealed by ROV dives

NASA Astrophysics Data System (ADS)

Embley, R. W.; Resing, J. A.; Tebo, B.; Baker, E. T.; Butterfield, D. A.; Chadwick, B.; Davis, R.; de Ronde, C. E.; Lilley, M. D.; Lupton, J. E.; Merle, S. G.; Rubin, K. H.; Shank, T. M.; Walker, S. L.; Arculus, R. J.; Bobbitt, A. M.; Buck, N.; Caratori Tontini, F.; Crowhurst, P. V.; Mitchell, E.; Olson, E. J.; Ratmeyer, V.; Richards, S.; Roe, K. K.; Keener, P.; Martinez Lyons, A.; Sheehan, C.; Brian, R.

2013-12-01

Dives with the QUEST 4000 ROV (Remotely Operated Vehicle) in September 2012 discovered nine hydrothermal sites in the arc and rear-arc region of the NE Lau Basin in 1150 m to 2630 m depth. These sites, originally detected by water column and seafloor surveys conducted in 2008-2011, include: (1) a paired sulfur-rich/black smoker field on the summit of a tectonically deformed magmatic arc volcano (Niua), (2) fracture-controlled black smoker venting on several small en echelon seamounts (north Matas) that lie between the magmatic arc and the backarc spreading center and (3) a magmatic degassing site on the summit of a dacite cone within a large (~12 km diameter) caldera volcano (Niuatahi). Dives at West Mata Seamount, which was undergoing strombolian volcanic activity and effusive rift-zone eruptions from 2008 to 2010, revealed a dormant volcanic phase in September 2012, with continued low-temperature diffuse venting. The high-temperature venting is likely driven by magmatic heat indicative of underlying partial melt zones and/or melt pockets distributed through the region. The occurrence of the youngest known boninite eruptions on the Mata volcanoes is consistent with subduction fluid flux melting extending into the rear-arc zone. Extension related to the transition from subduction to strike-slip motion of the northern Tonga Arc over the active Subduction-Transform Edge Propagator (STEP) fault probably contributes to the enhanced volcanism/hydrothermal activity in the NE Lau Basin. Chemosynthetic ecosystems at these sites range from mostly motile, lower diversity ecosystems at the eruptive/magmatically-degassing sites to higher diversity ecosystems with less mobile faunal components at the black-smoker systems. The wide range of fluid chemistry, water depth and geologic settings of the hydrothermal systems in this area provides an intriguing template to study the interaction of hydrothermal fluid chemistry, chemosynthetic habitats and their geologic underpinning

Chronology of volcanic events in the eastern Philippine Sea

NASA Astrophysics Data System (ADS)

Meijer, Arend; Reagan, Mark; Ellis, Howard; Shafiqullah, Muhammad; Sutter, John; Damon, Paul; Kling, Stanley

Radiometric and paleontologic ages of samples from chiefly volcanic sections exposed on Guam, Saipan, and in the Palau Islands were determined to provide an improved temporal framework for tectonic and petrologic models for the evolution of the eastern Philippine Sea. The oldest arc related volcanic rocks found in this area are from the Facpi formation on Guam dated at 43.8±1.6 m.y. B.P. (late middle Eocene). Evidence for late Eocene, early Oligocene, and middle Miocene arc volcanism was also found in the Mariana fore arc. The Palau Islands contain volcanic units of late Eocene(?), early Oligocene and early Miocene age. A minimum age of 1.3±0.2 m.y. has been established for the Mariana active arc. Overall, the new data are consistent with Karig's (1971) model for the tectonic evolution of the eastern Philippine Sea. Whether or not arc volcanism and interarc basin spreading can take place at the same time has not been resolved, although no evidence of synchroneity has been found for at least the Parece Vela Basin—South Honshu Ridge arc system.

Preliminary volcano-hazard assessment for the Tanaga volcanic cluster, Tanaga Island, Alaska

USGS Publications Warehouse

Coombs, Michelle L.; McGimsey, Robert G.; Browne, Brandon L.

2007-01-01

Summary of Volcano Hazards at Tanaga Volcanic Cluster The Tanaga volcanic cluster lies on the northwest part of Tanaga Island, about 100 kilometers west of Adak, Alaska, and 2,025 kilometers southwest of Anchorage, Alaska. The cluster consists of three volcanoes-from west to east, they are Sajaka, Tanaga, and Takawangha. All three volcanoes have erupted in the last 1,000 years, producing lava flows and tephra (ash) deposits. A much less frequent, but potentially more hazardous phenomenon, is volcanic edifice collapse into the sea, which likely happens only on a timescale of every few thousands of years, at most. Parts of the volcanic bedrock near Takawangha have been altered by hydrothermal activity and are prone to slope failure, but such events only present a local hazard. Given the volcanic cluster's remote location, the primary hazard from the Tanaga volcanoes is airborne ash that could affect aircraft. In this report, we summarize the major volcanic hazards associated with the Tanaga volcanic cluster.

Origin of Holocene trachyte lavas of the Quetrupillán volcanic complex, Chile: Examples of residual melts in a rejuvenated crystalline mush reservoir

NASA Astrophysics Data System (ADS)

Brahm, Raimundo; Parada, Miguel Angel; Morgado, Eduardo; Contreras, Claudio; McGee, Lucy Emma

2018-05-01

The Quetrupillán Volcanic Complex (QVC) is a stratovolcano placed in the center of a NW-SE volcanic chain, between Villarrica volcano and Lanín volcano, in the Central Southern Volcanic Zone of the Andes. Its youngest effusive products are dominated by crystal-poor (most samples with <9 vol% phenocrysts), crystal clot-bearing trachytes (from 64.6 up to 66.2 wt% SiO2), whereas the oldest units are mainly basaltic andesites. Two-stage generation of QVC trachytes by differentiation at shallow depth (<1 kbar) and NNO-QFM oxidation conditions were obtained from initial melt compositions equivalent to the Huililco basalts, a small eruptive centre located ca. 12 km NE of the QVC main vent. Pyroxene-bearing crystal clots, locally abundant in the trachytes, were formed at 900-960 °C (±55 °C) and represent a dismembered crystal mush from which interstitial trachytic melts were extracted and transported upward before eruption. Heating of the crystal mush by a hotter magma recharge is inferred from complex zoned plagioclases formed at higher crystallization temperatures (50-90 °C) than those obtained from pyroxene. Ca-rich plagioclase overgrowths around more albitic cores, followed by an external rim of similar composition to the core are interpreted as restoration to the initial conditions of plagioclase crystallization after the mentioned heating event. Additionally, a late heating of up to 150 °C just prior to eruption is recorded by Fe-Ti oxide thermometry.

2012 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

USGS Publications Warehouse

Herrick, Julie A.; Neal, Christina A.; Cameron, Cheryl E.; Dixon, James P.; McGimsey, Robert G.

2014-01-01

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, or suspected unrest at 11 volcanic centers in Alaska during 2012. Of the two verified eruptions, one (Cleveland) was clearly magmatic and the other (Kanaga) was most likely a single phreatic explosion. Two other volcanoes had notable seismic swarms that probably were caused by magmatic intrusions (Iliamna and Little Sitkin). For each period of clear volcanic unrest, AVO staff increased monitoring vigilance as needed, reviewed eruptive histories of the volcanoes in question to help evaluate likely outcomes, and shared observations and interpretations with the public. 2012 also was the 100th anniversary of Alaska’s Katmai-Novarupta eruption of 1912, the largest eruption on Earth in the 20th century and one of the most important volcanic eruptions in modern times. AVO marked this occasion with several public events.

Volcanic eruption source parameters from active and passive microwave sensors

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Volcanic soil gas 4He/CO2 ratio: a useful geochemical tool for eruption forecasting

NASA Astrophysics Data System (ADS)

Asensio-Ramos, M.; Perez, N. M.; Padron, E.; Melián, G.; Hernandez Perez, P. A.; Padilla, G.; Barrancos, J.; Rodríguez, F.; Sumino, H.; Calvo, D.

2016-12-01

Magmatic gases that percolate through volcano's porous flanks in a non-visible (diffuse) way disturb the chemical composition of soil gases at the surface environment of the volcano, generating enrichments of CO2, He and other gases. Two of the gases which have attracted attention in soil degassing studies are He and CO2 because both species have similar low solubility in silicate melts. However, once they are exsolved from the melts, their movement through the crust towards the surface is very different: CO2, which is a reactive gas, is affected by the occurrence of interfering processes, while interaction of He during its ascent is minimum. Their geochemical differences yield higher relative He/CO2 ratios in the fumarole gases than is actually present in the magma, but it decreases when the magma reservoir reaches enough pressure to generate incipient fracture systems approaching the eruption. In this work, we present quasi daily estimations of diffusive He through the whole surface of El Hierro, the youngest island of the Canarian archipelago, considering He emission data reported in the literature (Padrón et al., 2013. Geology, 41, 539-542), using the same procedure as for diffuse CO2 emission time series (Melián et al., 2014. J. Geophys. Res., 119, 6976-6991). After the occurrence of more than 11,000 seismic events, a shallow submarine eruption about 2 km off the south coast in the southernmost part of El Hierro, started in October 12, 2011 and lasted for 5 month. The herein presented methodology enables the calculation of the diffuse He/CO2 emission ratio of the entire island during the volcanic unrest. Two different emission peaks for both He and CO2, with approximately the same delay between them ( 23 days), were observed. The combination of both time series resulted in a drastic increase in the He/CO2 emission ratio of the island (up to 1.1×10-3) two weeks before the eruption onset. Additionally, a second significant He/CO2 emission peak (up to 5.5×10

Potential hazards from future volcanic eruptions in California

USGS Publications Warehouse

Miller, C. Dan

1989-01-01

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

Volcanic passive margins: another way to break up continents

PubMed Central

Geoffroy, L.; Burov, E. B.; Werner, P.

2015-01-01

Two major types of passive margins are recognized, i.e. volcanic and non-volcanic, without proposing distinctive mechanisms for their formation. Volcanic passive margins are associated with the extrusion and intrusion of large volumes of magma, predominantly mafic, and represent distinctive features of Larges Igneous Provinces, in which regional fissural volcanism predates localized syn-magmatic break-up of the lithosphere. In contrast with non-volcanic margins, continentward-dipping detachment faults accommodate crustal necking at both conjugate volcanic margins. These faults root on a two-layer deformed ductile crust that appears to be partly of igneous nature. This lower crust is exhumed up to the bottom of the syn-extension extrusives at the outer parts of the margin. Our numerical modelling suggests that strengthening of deep continental crust during early magmatic stages provokes a divergent flow of the ductile lithosphere away from a central continental block, which becomes thinner with time due to the flow-induced mechanical erosion acting at its base. Crustal-scale faults dipping continentward are rooted over this flowing material, thus isolating micro-continents within the future oceanic domain. Pure-shear type deformation affects the bulk lithosphere at VPMs until continental breakup, and the geometry of the margin is closely related to the dynamics of an active and melting mantle. PMID:26442807

Volcanic passive margins: another way to break up continents.

PubMed

Geoffroy, L; Burov, E B; Werner, P

2015-10-07

Two major types of passive margins are recognized, i.e. volcanic and non-volcanic, without proposing distinctive mechanisms for their formation. Volcanic passive margins are associated with the extrusion and intrusion of large volumes of magma, predominantly mafic, and represent distinctive features of Larges Igneous Provinces, in which regional fissural volcanism predates localized syn-magmatic break-up of the lithosphere. In contrast with non-volcanic margins, continentward-dipping detachment faults accommodate crustal necking at both conjugate volcanic margins. These faults root on a two-layer deformed ductile crust that appears to be partly of igneous nature. This lower crust is exhumed up to the bottom of the syn-extension extrusives at the outer parts of the margin. Our numerical modelling suggests that strengthening of deep continental crust during early magmatic stages provokes a divergent flow of the ductile lithosphere away from a central continental block, which becomes thinner with time due to the flow-induced mechanical erosion acting at its base. Crustal-scale faults dipping continentward are rooted over this flowing material, thus isolating micro-continents within the future oceanic domain. Pure-shear type deformation affects the bulk lithosphere at VPMs until continental breakup, and the geometry of the margin is closely related to the dynamics of an active and melting mantle.

Arctic “ozone hole” in a cold volcanic stratosphere

PubMed Central

Tabazadeh, A.; Drdla, K.; Schoeberl, M. R.; Hamill, P.; Toon, O. B.

2002-01-01

Optical depth records indicate that volcanic aerosols from major eruptions often produce clouds that have greater surface area than typical Arctic polar stratospheric clouds (PSCs). A trajectory cloud–chemistry model is used to study how volcanic aerosols could affect springtime Arctic ozone loss processes, such as chlorine activation and denitrification, in a cold winter within the current range of natural variability. Several studies indicate that severe denitrification can increase Arctic ozone loss by up to 30%. We show large PSC particles that cause denitrification in a nonvolcanic stratosphere cannot efficiently form in a volcanic environment. However, volcanic aerosols, when present at low altitudes, where Arctic PSCs cannot form, can extend the vertical range of chemical ozone loss in the lower stratosphere. Chemical processing on volcanic aerosols over a 10-km altitude range could increase the current levels of springtime column ozone loss by up to 70% independent of denitrification. Climate models predict that the lower stratosphere is cooling as a result of greenhouse gas built-up in the troposphere. The magnitude of column ozone loss calculated here for the 1999–2000 Arctic winter, in an assumed volcanic state, is similar to that projected for a colder future nonvolcanic stratosphere in the 2010 decade. PMID:11854461

New ground-based lidar enables volcanic CO2 flux measurements.

PubMed

Aiuppa, Alessandro; Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Nuvoli, Marcello; Chiodini, Giovanni; Minopoli, Carmine; Tamburello, Giancarlo

2015-09-01

There have been substantial advances in the ability to monitor the activity of hazardous volcanoes in recent decades. However, obtaining early warning of eruptions remains challenging, because the patterns and consequences of volcanic unrests are both complex and nonlinear. Measuring volcanic gases has long been a key aspect of volcano monitoring since these mobile fluids should reach the surface long before the magma. There has been considerable progress in methods for remote and in-situ gas sensing, but measuring the flux of volcanic CO2-the most reliable gas precursor to an eruption-has remained a challenge. Here we report on the first direct quantitative measurements of the volcanic CO2 flux using a newly designed differential absorption lidar (DIAL), which were performed at the restless Campi Flegrei volcano. We show that DIAL makes it possible to remotely obtain volcanic CO2 flux time series with a high temporal resolution (tens of minutes) and accuracy (<30%). The ability of this lidar to remotely sense volcanic CO2 represents a major step forward in volcano monitoring, and will contribute improved volcanic CO2 flux inventories. Our results also demonstrate the unusually strong degassing behavior of Campi Flegrei fumaroles in the current ongoing state of unrest.

Global volcanic aerosol properties derived from emissions, 1990-2014, using CESM1(WACCM)

NASA Astrophysics Data System (ADS)

Mills, Michael J.; Schmidt, Anja; Easter, Richard; Solomon, Susan; Kinnison, Douglas E.; Ghan, Steven J.; Neely, Ryan R.; Marsh, Daniel R.; Conley, Andrew; Bardeen, Charles G.; Gettelman, Andrew

2016-03-01

Accurate representation of global stratospheric aerosols from volcanic and nonvolcanic sulfur emissions is key to understanding the cooling effects and ozone losses that may be linked to volcanic activity. Attribution of climate variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the rate of global average temperature increases. We have compiled a database of volcanic SO2 emissions and plume altitudes for eruptions from 1990 to 2014 and developed a new prognostic capability for simulating stratospheric sulfate aerosols in the Community Earth System Model. We used these combined with other nonvolcanic emissions of sulfur sources to reconstruct global aerosol properties from 1990 to 2014. Our calculations show remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD) and with in situ measurements of stratospheric aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD calculations represent a clear improvement over available satellite-based analyses, which generally ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at middle and high latitudes. Our SAD calculations greatly improve on that provided for the Chemistry-Climate Model Initiative, which misses about 60% of the SAD measured in situ on average during both volcanically active and volcanically quiescent periods.

Volcanic hazards: Perspectives from eruption prediction to risk assessment for disposal of radioactive waste

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

Crowe, B.

1980-12-31

This document summarizes an oral presentation that described the potential for volcanic activity at the proposed Yucca Mountain, Texas repository site. Yucca Mountain is located in a broad zone of volcanic activity known as the Death Valley-Pancake Ridge volcanic zone. The probability estimate for the likelihood that some future volcanic event will intersect a buried repository at Yucca Mountain is low. Additionally, the radiological consequences of penetration of a repository by basaltic magma followed by eruption of the magma at the surface are limited. The combination of low probability and limited consequence suggests that the risk posed by waste storagemore » at this site is low. (TEM)« less

Backprojection of volcanic tremor

USGS Publications Warehouse

Haney, Matthew M.

2014-01-01

Backprojection has become a powerful tool for imaging the rupture process of global earthquakes. We demonstrate the ability of backprojection to illuminate and track volcanic sources as well. We apply the method to the seismic network from Okmok Volcano, Alaska, at the time of an escalation in tremor during the 2008 eruption. Although we are able to focus the wavefield close to the location of the active cone, the network array response lacks sufficient resolution to reveal kilometer-scale changes in tremor location. By deconvolving the response in successive backprojection images, we enhance resolution and find that the tremor source moved toward an intracaldera lake prior to its escalation. The increased tremor therefore resulted from magma-water interaction, in agreement with the overall phreatomagmatic character of the eruption. Imaging of eruption tremor shows that time reversal methods, such as backprojection, can provide new insights into the temporal evolution of volcanic sources.

Preliminary Findings of Petrology and Geochemistry of The Aladaǧ Volcanic System and Surrounding Areas (Kars, Turkey)

NASA Astrophysics Data System (ADS)

Duru, Olgun; Keskin, Mehmet

2017-04-01

, and hyalopilitic textures. (2) The second stage lavas, covering large areas are andesitic to dacitic in composition, consisting of Plg and Px and amphibole (Amp) xenocrysts. (3) On the northwestern flank of the Gretater Aladaǧ, about twenty lava flows are exposed. These aphyric lavas consist of Plg and Opx. (4) The aphyric lavas of the Lesser Aladaǧ, in the northwest of the Greater Aladaǧ volcano, are basaltic andesitic in composition. In the northeast of the study area, Upper Pliocene lavas exposed on the southern edge of the Kars plateau are the youngest volcanic units which are basaltic in composition displaying porphyritic textures in the study area. They are composed of plagioclase and clinopyroxene phenocrysts. Volcanic products in the study area are calc-alkaline in character with a clear subduction signature. They show textures characteristic for magma mixing processes indicating periodic replenishment of magma chamber by primitive basaltic magmas. Our assimilation models indicate that AFC was an important process for the evolved lavas. However, AFC remained negligible during the magma chamber evolution of the basic volcanic units.

Opportunities for Monitoring Io's Volcanic Activity in the Visible and Infrared From JUICE - It's All About (Eruption) Style

NASA Astrophysics Data System (ADS)

Davies, Ashley; Matson, D.; McEwen, A. S.; Keszthelyi, L.

2012-10-01

The ESA Jupiter Icy Moons Explorer (JUICE) provides many opportunities for long-range monitoring of Io’s extraordinary silicate volcanic activity [1, 2]. A considerable amount of valuable work can be performed even with relatively low-spatial-resolution observations [2]. Techniques developed from the study of Galileo NIMS data and observations of terrestrial silicate volcanism allow the identification of likely eruption style [2] at many locations where the entire eruption is sub-pixel. Good temporal coverage, especially for episodic eruptions (including high-energy “outburst” eruptions), is important for modelling purposes. With opportunities to observe Io on a regular basis (hours-days) during cruise/orbital reduction phases, a visible-to-near-infrared mapping spectrometer (covering 0.4-5.5 µm) is the best instrument to chart the magnitude and variability of Io’s volcanic activity, allowing comparison with an existing and constantly expanding set of Io observations [e.g. 1, 3]. The eruption temperature of Io’s dominant silicate lava, a constraint on interior composition and conditions, is a major unanswered question in the wake of the Galileo mission [1]. A careful approach to instrument design is needed to ensure that observations by both imager and IR spectrometer on JUICE are capable of determining lava eruption temperature [e.g., 4] in low spatial resolution data. With an ideal thermal target (e.g., outburst eruption; the proposed lava lake at Pele) the imager should obtain multi-spectral data in a rapid sequence to allow stability of the thermal source to be quantified. Observations by imager and spectrometer have to be contemporaneous and unsaturated. References: [1] Davies, A. (2007) “Volcanism on Io”, Cam. Univ. Press. [2] Davies et al. (2010) JVGR, 194, 75-99. [3] Veeder et al. (2012) Icarus, 219, 701-722. [4] Davies et al. (2011) GRL, 38, L21308. This work was performed at the Jet Propulsion Laboratory-California Institute of Technology

Submarine Volcanic Morphology of Santorini Caldera, Greece

NASA Astrophysics Data System (ADS)

Nomikou, P.; Croff Bell, K.; Carey, S.; Bejelou, K.; Parks, M.; Antoniou, V.

2012-04-01

Santorini volcanic group form the central part of the modern Aegean volcanic arc, developed within the Hellenic arc and trench system, because of the ongoing subduction of the African plate beneath the European margin throughout Cenozoic. It comprises three distinct volcanic structures occurring along a NE-SW direction: Christianna form the southwestern part of the group, Santorini occupies the middle part and Koloumbo volcanic rift zone extends towards the northeastern part. The geology of the Santorini volcano has been described by a large number of researchers with petrological as well as geochronological data. The offshore area of the Santorini volcanic field has only recently been investigated with emphasis mainly inside the Santorini caldera and the submarine volcano of Kolumbo. In September 2011, cruise NA-014 on the E/V Nautilus carried out new surveys on the submarine volcanism of the study area, investigating the seafloor morphology with high-definition video imaging. Submarine hydrothermal vents were found on the seafloor of the northern basin of the Santorini caldera with no evidence of high temperature fluid discharges or massive sulphide formations, but only low temperature seeps characterized by meter-high mounds of bacteria-rich sediment. This vent field is located in line with the normal fault system of the Kolumbo rift, and also near the margin of a shallow intrusion that occurs within the sediments of the North Basin. Push cores have been collected and they will provide insights for their geochemical characteristics and their relationship to the active vents of the Kolumbo underwater volcano. Similar vent mounds occur in the South Basin, at shallow depths around the islets of Nea and Palaia Kameni. ROV exploration at the northern slopes of Nea Kameni revealed a fascinating underwater landscape of lava flows, lava spines and fractured lava blocks that have been formed as a result of 1707-1711 and 1925-1928 AD eruptions. A hummocky topography at

Simulating a Volcanic Crisis in the Classroom.

ERIC Educational Resources Information Center

Harpp, Karen S.; Sweeney, William J.

2002-01-01

Reports on the design of a multi-week cooperative learning activity for an undergraduate introductory volcanology class which culminates in the simulation of a volcanic monitoring crisis. Suggests that this activity creates an effective and exciting learning environment in which students have the opportunity to apply theoretical concepts to a more…

Raman spectroscopy of volcanic lavas and inclusions of relevance to astrobiological exploration.

PubMed

Jorge-Villar, Susana E; Edwards, Howell G M

2010-07-13

Volcanic eruptions and lava flows comprise one of the most highly stressed terrestrial environments for the survival of biological organisms; the destruction of botanical and biological colonies by molten lava, pyroclastic flows, lahars, poisonous gas emissions and the deposition of highly toxic materials from fumaroles is the normal expectation from such events. However, the role of lichens and cyanobacteria in the earlier colonization of volcanic lava outcrops has now been recognized. In this paper, we build upon earlier Raman spectroscopic studies on extremophilic colonies in old lava flows to assess the potential of finding evidence of biological colonization in more recent lava deposits that would inform, first, the new colonization of these rocks and also provide evidence for the relict presence of biological colonies that existed before the volcanism occurred and were engulfed by the lava. In this research, samples were collected from a recent expedition to the active volcano at Kilauea, Hawaii, which comprises very recent lava flows, active fumaroles and volcanic rocks that had broken through to the ocean and had engulfed a coral reef. The Raman spectra indicated that biological and geobiological signatures could be identified in the presence of geological matrices, which is encouraging for the planned exploration of Mars, where it is believed that there is evidence of an active volcanism that perhaps could have preserved traces of biological activity that once existed on the planet's surface, especially in sites near the old Martian oceans.

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

NASA Technical Reports Server (NTRS)

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

1973-01-01

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

Ambient Noise Surface Wave Tomography of the volcanic systems of eastern Iceland

NASA Astrophysics Data System (ADS)

Green, R. G.; Priestley, K. F.; White, R. S.

2015-12-01

The Vatnajökull region of central-east Iceland lies above the head of the Iceland mantle plume where the crust is thickest due to enhanced melt supply. As a result the region contains a high density of volcanic rift systems, with six large subglacial central volcanoes. Due to the ice cover, the geological structure of the area and the location of past eruptions are poorly known. Imaging of the crustal velocity heterogeneities beneath the ice sheet aims to reveal much in terms of the structure of these volcanic plumbing systems. Mapping of significant velocity changes through time may also be indicative of movement of melt around the central volcanoes; one of which (Bárðarbunga) experienced a major rifting event in August 2014 (Sigmundsson et al. Nature 2015, Green et al. Nature Geosci. 2015). We present results from tomographic imaging of the volcanic systems in the region, using continuous data from a local broadband seismic network in central-east Iceland which provides excellent ray path coverage of the volcanic systems. This is supplemented by data from the HOTSPOT and ICEMELT experiments and the permanent monitoring stations of the Icelandic Meteorological Office. We process the continuous data following Benson et al. 2007 and automatic frequency-time analysis (FTAN) routines are used to extract more than 9000 dispersion measurements. We then generate Rayleigh wave group velocity maps which we present here. We find low velocity regions beneath the Vatnajökull icecap which are bounded by the surface expression of the volcanic rift systems. The lower velocities also extend north-west to the volcanic system under the Hofsjökull ice cap, and northwards towards Askja and the volcanic systems of the northern volcanic zone. We also produce locations and focal mechanisms of earthquakes caused by magmatic and hydrothermal activity to correlate structure with the activity of the volcanic systems.

Autonomous Sensorweb Operations for Integrated Space, In-Situ Monitoring of Volcanic Activity

NASA Technical Reports Server (NTRS)

Chien, Steve A.; Doubleday, Joshua; Kedar, Sharon; Davies, Ashley G.; Lahusen, Richard; Song, Wenzhan; Shirazi, Behrooz; Mandl, Daniel; Frye, Stuart

2010-01-01

We have deployed and demonstrated operations of an integrated space in-situ sensorweb for monitoring volcanic activity. This sensorweb includes a network of ground sensors deployed to the Mount Saint Helens volcano as well as the Earth Observing One spacecraft. The ground operations and space operations are interlinked in that ground-based intelligent event detections can cause the space segment to acquire additional data via observation requests and space-based data acquisitions (thermal imagery) can trigger reconfigurations of the ground network to allocate increased bandwidth to areas of the network best situated to observe the activity. The space-based operations are enabled by an automated mission planning and tasking capability which utilizes several Opengeospatial Consortium (OGC) Sensorweb Enablement (SWE) standards which enable acquiring data, alerts, and tasking using web services. The ground-based segment also supports similar protocols to enable seamless tasking and data delivery. The space-based segment also supports onboard development of data products (thermal summary images indicating areas of activity, quicklook context images, and thermal activity alerts). These onboard developed products have reduced data volume (compared to the complete images) which enables them to be transmitted to the ground more rapidly in engineering channels.

Compositional heterogeneity of the Sugarloaf melilite nephelinite flow, Honolulu Volcanics, Hawai'i

NASA Astrophysics Data System (ADS)

Clague, David A.; Frey, Frederick A.; Garcia, Michael O.; Huang, Shichun; McWilliams, Michael; Beeson, Melvin H.

2016-07-01

The Sugarloaf flow is a melilite nephelinite erupted from the Tantalus rift during rejuvenated-stage volcanism on O'ahu, the Honolulu Volcanics. The flow ponded in Mānoa Valley forming a ∼15 m thick flow which was cored and sampled in a quarry. Nepheline from a pegmatoid segregation in the flow yielded a 40Ar-39Ar age of 76 ka. This age, combined with others, indicates that the Tantalus rift eruptions are some of the youngest on O'ahu. Honolulu Volcanics erupt on average about every 35-40 ka indicating that future eruptions are possible. We evaluated the compositional variability of 19 samples from the flow, including 14 from the core. Twelve samples are representative of the bulk flow, four are dark- or light-colored variants, one is a heavy rare earth element (REE)-enriched pegmatoid, and two visually resemble the bulk flow, but have chemical characteristics of the dark and light variants. Our objective was to determine intraflow heterogeneity in mineralogy and composition. Variable abundances of Na2O, K2O, Sr, Ba, Rb, Pb and U in the flow were caused by post-eruptive mobility in a vapor phase, most likely during or soon after flow emplacement, and heterogeneous deposition of secondary calcite and zeolites. Relative to fine-grained samples, a pegmatoid vein that crosscuts the flow is enriched in incompatible trace elements except Sr and TiO2. Element mobility after eruption introduced scatter in trace element ratios including light-REE/heavy-REE, and all ratios involving mobile elements K, Rb, Ba, Sr, Pb, and U. Lavas from some of the 37 Honolulu Volcanics vents have crosscutting REE patterns in a primitive mantle-normalized plot. Such patterns have been interpreted to reflect variable amounts of residual garnet during partial melting. Previous studies of lavas from different vents concluded that garnet, phlogopite, amphibole, and Fe-Ti oxides were residual phases of the partial melting processes that created the Honolulu Volcanics (Clague and Frey, 1982; Yang