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Sample records for copahue volcano southern

  1. The 2012-2014 eruptive cycle of Copahue Volcano, Southern Andes. Magmatic-Hydrothermal system interaction and manifestations.

    NASA Astrophysics Data System (ADS)

    Morales, Sergio; Alarcón, Alex; Basualto, Daniel; Bengoa, Cintia; Bertín, Daniel; Cardona, Carlos; Córdova, Maria; Franco, Luis; Gil, Fernando; Hernandez, Erasmo; Lara, Luis; Lazo, Jonathan; Mardones, Cristian; Medina, Roxana; Peña, Paola; Quijada, Jonathan; San Martín, Juan; Valderrama, Oscar

    2015-04-01

    Copahue Volcano (COPV), in Southern Andes of Chile, is an andesitic-basaltic stratovolcano, which is located on the western margin of Caviahue Caldera. The COPV have a NE-trending fissure with 9 aligned vents, being El Agrio the main currently active vent, with ca. 400 m in diameter. The COPV is placed into an extensive hydrothermal system which has modulated its recent 2012-2014 eruptive activity, with small phreatic to phreatomagmatic eruptions and isolated weak strombolian episodes and formation of crater lakes inside the main crater. Since 2012, the Southern Andes Volcano Observatory (OVDAS) carried out the real-time monitoring with seismic broadband stations, GPS, infrasound sensors and webcams. In this work, we report pre, sin, and post-eruptive seismic activity of the last two main eruptions (Dec, 2012 and Oct, 2014) both with different seismic precursors and superficial activity, showing the second one a particularly appearance of seismic quiescence episodes preceding explosive activity, as an indicator of interaction between magmatic-hydrothermal systems. The first episode, in late 2012, was characterized by a low frequency (0.3-0.4 Hz and 1.0-1.5 Hz) continuous tremor which increased gradually from background noise level amplitude to values of reduced displacement (DR), close to 50 cm2 at the peak of the eruption, reaching an eruptive column of ~1.5 km height. After few months of recording low energy seismicity, a sequence of low frequency, repetitive and low energy seismic events arose, with a frequency of occurrence up to 300 events/hour. Also, the VLP earthquakes were added to the record probably associated with magma intrusion into a deep magmatic chamber during all stages of eruptive process, joined to the record of VT seismicity during the same period, which is located throughout the Caviahue Caldera area. Both kind of seismic patterns were again recorded in October 2014, being the precursor of the new eruptive cycle at this time as well as the

  2. Copahue volcano and its regional magmatic setting

    USGS Publications Warehouse

    Varekamp, J C; Zareski, J E; Camfield, L M; Todd, Erin

    2016-01-01

    Copahue volcano (Province of Neuquen, Argentina) has produced lavas and strombolian deposits over several 100,000s of years, building a rounded volcano with a 3 km elevation. The products are mainly basaltic andesites, with the 2000–2012 eruptive products the most mafic. The geochemistry of Copahue products is compared with those of the main Andes arc (Llaima, Callaqui, Tolhuaca), the older Caviahue volcano directly east of Copahue, and the back arc volcanics of the Loncopue graben. The Caviahue rocks resemble the main Andes arc suite, whereas the Copahue rocks are characterized by lower Fe and Ti contents and higher incompatible element concentrations. The rocks have negative Nb-Ta anomalies, modest enrichments in radiogenic Sr and Pb isotope ratios and slightly depleted Nd isotope ratios. The combined trace element and isotopic data indicate that Copahue magmas formed in a relatively dry mantle environment, with melting of a subducted sediment residue. The back arc basalts show a wide variation in isotopic composition, have similar water contents as the Copahue magmas and show evidence for a subducted sedimentary component in their source regions. The low 206Pb/204Pb of some backarc lava flows suggests the presence of a second endmember with an EM1 flavor in its source. The overall magma genesis is explained within the context of a subducted slab with sediment that gradually looses water, water-mobile elements, and then switches to sediment melt extracts deeper down in the subduction zone. With the change in element extraction mechanism with depth comes a depletion and fractionation of the subducted complex that is reflected in the isotope and trace element signatures of the products from the main arc to Copahue to the back arc basalts.

  3. Acid fluids from Copahue Volcano, Argentina, and their environmental effects

    NASA Astrophysics Data System (ADS)

    Varekamp, J. C.; Kading, T.

    2010-12-01

    The acid hydrothermal system of Copahue volcano (province of Neuquen, Argentina) consists of a crater lake, acid hot springs (both with pH values of <1 to 2) and a severely acidified fluvial-lake system, with the voluminous Lake Caviahue (0.5 km3; pH 2.2 - 3). Annual measurements of river water fluxes and water compositions and vertical lake water profiles provide a 12 year record of geochemical evolution of the system. Copahue erupted in 2000, and the hydrothermal dissolved element fluxes peaked at that time. Since 2001, the K and Al fluxes have decreased notably as a result of alunite saturation within the hydrothermal system, whereas over the last few years redissolution of that alunite has led to increases in K and Al discharges. The fluxes of Mg and Fe have remained high over time, while the overall system has become more dilute since 2000. Once the distal downstream system reached pH values of 2.9-3.2, the mineral Schwertmannite started to precipitate through a bacterially mediated pathway. The precipitation front gradually moved upstream with ongoing dilution, and reached the exit of Lake Caviahue in 2009. The lake bottom waters were already saturated with the mineral at that time, and if this trend continues, the currently clear blue lake may turn into a bright yellow-brown mass of Schwertmannite over the next few years. Schwertmannite is common in acid mine drainage fluids but has not often been described from volcanic environments. It strongly adsorbs oxyanions (or structurally incorporates them) and the precipitates contain up to 6000 ppm P, 1100 ppm V and 1000 ppm As. The Schwertmannite appears to convert to goethite-like minerals over time, although the exact stoichiometry has been difficult to constrain (variable mixtures of FeOOH and Fe8O8(OH)6SO4 nH2O). The oxyanions appear to remain in the mineral mix during aging. If Lake Caviahue becomes a focus of Schwertmannite deposition, the precipitates will scavenge As, P and V from the watercolumn and

  4. Hydrothermal element fluxes from Copahue, Argentina: A "beehive" volcano in turmoil

    USGS Publications Warehouse

    Varekamp, J.C.; Ouimette, A.P.; Herman, S.W.; Bermudez, A.; Delpino, D.

    2001-01-01

    Copahue volcano erupted altered rock debris, siliceous dust, pyroclastic sulfur, and rare juvenile fragments between 1992 and 1995, and magmatic eruptions occurred in July-October 2000. Prior to 2000, the Copahue crater lake, acid hot springs, and rivers carried acid brines with compositions that reflected close to congruent rock dissolution. The ratio between rock-forming elements and chloride in the central zone of the volcano-hydrothermal system has diminished over the past few years, reflecting increased water/rock ratios as a result of progressive rock dissolution. Magmatic activity in 2000 provided fresh rocks for the acid fluids, resulting in higher ratios between rock-forming elements and chloride in the fluids and enhanced Mg fluxes. The higher Mg fluxes started several weeks prior to the eruption. Model data on the crater lake and river element flux determinations indicate that Copahue volcano was hollowed out at a rate of about 20 000-25 000 m3/yr, but that void space was filled with about equal amounts of silica and liquid elemental sulfur. The extensive rock dissolution has weakened the internal volcanic structure, making flank collapse a volcanic hazard at Copahue.

  5. Imaging irregular magma reservoirs with InSAR and GPS observations: Application to Kilauea and Copahue volcanoes

    NASA Astrophysics Data System (ADS)

    Lundgren, P.; Camacho, A.; Poland, M. P.; Miklius, A.; Samsonov, S. V.; Milillo, P.

    2013-12-01

    The availability of synthetic aperture radar (SAR) interferometry (InSAR) data has increased our awareness of the complexity of volcano deformation sources. InSAR's spatial completeness helps identify or clarify source process mechanisms at volcanoes (i.e. Mt. Etna east flank motion; Lazufre crustal magma body; Kilauea dike complexity) and also improves potential model realism. In recent years, Bayesian inference methods have gained widespread use because of their ability to constrain not only source model parameters, but also their uncertainties. They are computationally intensive, however, which tends to limit them to a few geometrically rather simple source representations (for example, spheres). An alternative approach involves solving for irregular pressure and/or density sources from a three-dimensional (3-D) grid of source/density cells. This method has the ability to solve for arbitrarily shaped bodies of constant absolute pressure/density difference. We compare results for both Bayesian (a Markov chain Monte Carlo algorithm) and the irregular source methods for two volcanoes: Kilauea, Hawaii, and Copahue, Argentina-Chile border. Kilauea has extensive InSAR and GPS databases from which to explore the results for the irregular method with respect to the Bayesian approach, prior models, and an extensive set of ancillary data. One caveat, however, is the current restriction in the irregular model inversion to volume-pressure sources (and at a single excess pressure change), which limits its application in cases where sources such as faults or dikes are present. Preliminary results for Kilauea summit deflation during the March 2011 Kamoamoa eruption suggests a northeast-elongated magma body lying roughly 1-1.5 km below the surface. Copahue is a southern Andes volcano that has been inflating since early 2012, with intermittent summit eruptive activity since late 2012. We have an extensive InSAR time series from RADARSAT-2 and COSMO-SkyMed data, although both are

  6. Intense magmatic degassing through the lake of Copahue volcano, 2013-2014

    NASA Astrophysics Data System (ADS)

    Tamburello, G.; Agusto, M.; Caselli, A.; Tassi, F.; Vaselli, O.; Calabrese, S.; Rouwet, D.; Capaccioni, B.; Di Napoli, R.; Cardellini, C.; Chiodini, G.; Bitetto, M.; Brusca, L.; Bellomo, S.; Aiuppa, A.

    2015-09-01

    Here we report on the first assessment of volatile fluxes from the hyperacid crater lake hosted within the summit crater of Copahue, a very active volcano on the Argentina-Chile border. Our observations were performed using a variety of in situ and remote sensing techniques during field campaigns in March 2013, when the crater hosted an active fumarole field, and in March 2014, when an acidic volcanic lake covered the fumarole field. In the latter campaign, we found that 566 to 1373 t d-1 of SO2 were being emitted from the lake in a plume that appeared largely invisible. This, combined with our derived bulk plume composition, was converted into flux of other volcanic species (H2O ~ 10989 t d-1, CO2 ~ 638 t d-1, HCl ~ 66 t d-1, H2 ~ 3.3 t d-1, and HBr ~ 0.05 t d-1). These levels of degassing, comparable to those seen at many open-vent degassing arc volcanoes, were surprisingly high for a volcano hosting a crater lake. Copahue's unusual degassing regime was also confirmed by the chemical composition of the plume that, although issuing from a hot (65°C) lake, preserves a close-to-magmatic signature. EQ3/6 models of gas-water-rock interaction in the lake were able to match observed compositions and demonstrated that magmatic gases emitted to the atmosphere were virtually unaffected by scrubbing of soluble (S and Cl) species. Finally, the derived large H2O flux (10,988 t d-1) suggested a mechanism in which magmatic gas stripping drove enhanced lake water evaporation, a process likely common to many degassing volcanic lakes worldwide.

  7. Utilizing NASA Earth Observations to Model Volcanic Hazard Risk Levels in Areas Surrounding the Copahue Volcano in the Andes Mountains

    NASA Astrophysics Data System (ADS)

    Keith, A. M.; Weigel, A. M.; Rivas, J.

    2014-12-01

    Copahue is a stratovolcano located along the rim of the Caviahue Caldera near the Chile-Argentina border in the Andes Mountain Range. There are several small towns located in proximity of the volcano with the two largest being Banos Copahue and Caviahue. During its eruptive history, it has produced numerous lava flows, pyroclastic flows, ash deposits, and lahars. This isolated region has steep topography and little vegetation, rendering it poorly monitored. The need to model volcanic hazard risk has been reinforced by recent volcanic activity that intermittently released several ash plumes from December 2012 through May 2013. Exposure to volcanic ash is currently the main threat for the surrounding populations as the volcano becomes more active. The goal of this project was to study Copahue and determine areas that have the highest potential of being affected in the event of an eruption. Remote sensing techniques were used to examine and identify volcanic activity and areas vulnerable to experiencing volcanic hazards including volcanic ash, SO2 gas, lava flow, pyroclastic density currents and lahars. Landsat 7 Enhanced Thematic Mapper Plus (ETM+), Landsat 8 Operational Land Imager (OLI), EO-1 Advanced Land Imager (ALI), Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Shuttle Radar Topography Mission (SRTM), ISS ISERV Pathfinder, and Aura Ozone Monitoring Instrument (OMI) products were used to analyze volcanic hazards. These datasets were used to create a historic lava flow map of the Copahue volcano by identifying historic lava flows, tephra, and lahars both visually and spectrally. Additionally, a volcanic risk and hazard map for the surrounding area was created by modeling the possible extent of ash fallout, lahars, lava flow, and pyroclastic density currents (PDC) for future eruptions. These model results were then used to identify areas that should be prioritized for disaster relief and evacuation orders.

  8. Spatial Distribution of b-value of the Copahue volcano during 2012-2014 eruptive period: Relationship between magmatic and hydrothermal system

    NASA Astrophysics Data System (ADS)

    Lazo, Jonathan; Basualto, Daniel; Bengoa, Cintia; Cardona, Carlos; Franco, Luis; Gil-Cruz, Fernando; Hernández, Erasmo; Lara, Luis; Lundgren, Paul; Medina, Roxana; Morales, Sergio; Peña, Paola; Quijada, Jonathan; Samsonov, Sergey; San Martin, Juan; Valderrama, Oscar

    2015-04-01

    Temporal and spatial variations of b-value have been interpreted as regional stress changes on active tectonic zones or magma ascent and/or hydrothermal fluids mobilization that could affect to active volcanic arc. Increasing of fluids pressure, medium heterogeneities or temperature changes would be the cause of these variations. The Copahue volcano is a shield strato-volcano that has been edified on the western margin of the Caviahue Caldera, located in the international border between Chile and Argentina, which contain an important geothermic field and is located at a horse-tail structure of the Liquiñe-Ofqui Fault Zone. The pre-fracture nature of its basement, as well as an extensive geothermic field, would be producing very complex conditions to fluids movement that could be exploring to use the 'b' value of the recorded seismicity between 2012 and 2014. Based in the database of VT seismic events, we used 2.073 events to calculate the b-value to obtain the 2D and 3D distribution maps. Results showed two anomalous zones: the first one located 9 Km to NE of the active crater, 3-6 Km depth, with high b-values (>1.2) that is associated with a very high production rate of small earthquakes that could suggest a brittle zone, located in the active geothermal field. The second zone, showed a low b-values (~ 0.7), located to east of the volcano edifice at <3 Km depth, associated to a zone where were generated larger magnitude events, suggesting a zone with more stress accumulation that well correlated with the deformation center detected by InSAR measurements. This zone could be interpreted as the magmatic source that interacts with the shallow hydrothermal system. Thus, in a very complex setting as a volcano sitting on top of a geothermal system, the b-value offers a tool to understand the distribution of the seismic sources and hence a physical constrain for the coupled magmatic/hydrothermal system.

  9. Seismic unrest at Katla Volcano- southern Iceland

    NASA Astrophysics Data System (ADS)

    jeddi, zeinab; Tryggvason, Ari; Gudmundsson, Olafur; Bödvarsson, Reynir; SIL Seismology Group

    2014-05-01

    Katla volcano is located on the propagating Eastern Volcanic Zone (EVZ) in South Iceland. It is located beneath Mýrdalsjökull ice-cap which covers an area of almost 600 km2, comprising the summit caldera and the eruption vents. 20 eruptions between 930 and 1918 with intervals of 13-95 years are documented at Katla which is one of the most active subglacial volcanoes in Iceland. Eruptions at Katla are mainly explosive due to the subglacial mode of extrusion and produce high eruption columns and catastrophic melt water floods (jökulhlaups). The present long Volcanic repose (almost 96 years) at Katla, the general unrest since 1955, and the 2010 eruption of the neighbouring Eyjafjallajökull volcano has prompted concerns among geoscientists about an imminent eruption. Thus, the volcano has been densely monitored by seismologists and volcanologists. The seismology group of Uppsala University as a partner in the Volcano Anatomy (VA) project in collaboration with the University of Iceland and the Icelandic Meteorological Office (IMO) installed 9 temporary seismic stations on and around the Mýrdalsjökull glacier in 2011. Another 10 permanent seismic stations are operated by IMO around Katla. The project's data collection is now finished and temporary stations were pulled down in August 2013. According to seismicity maps of the whole recording period, thousands of microearthquakes have occurred within the caldera region. At least three different source areas are active in Katla: the caldera region, the western Godaland region and a small cluster at the southern rim of Mýrdalsjökull near the glacial stream of Hafursarjökull. Seismicity in the southern flank has basically started after June 2011. The caldera events are mainly volcano-tectonic, while western and southern events are mostly long period (lp) and can be related to glacial or magmatic movement. One motivation of the VA Katla project is to better understand the physical mechanism of these lp events. Changes

  10. Draft Genome Sequence of the Sulfate-Reducing Bacterium Desulfotomaculum copahuensis Strain CINDEFI1 Isolated from the Geothermal Copahue System, Neuquén, Argentina.

    PubMed

    Willis Poratti, Graciana; Yaakop, Amira Suriaty; Chan, Chia Sing; Urbieta, M Sofía; Chan, Kok-Gan; Ee, Robson; Tan-Guan-Sheng, Adrian; Goh, Kian Mau; Donati, Edgardo R

    2016-01-01

    Desulfotomaculum copahuensis strain CINDEFI1 is a novel spore-forming sulfate-reducing bacterium isolated from the Copahue volcano area, Argentina. Here, we present its draft genome in which we found genes related with the anaerobic respiration of sulfur compounds similar to those present in the Copahue environment. PMID:27540078

  11. Draft Genome Sequence of the Sulfate-Reducing Bacterium Desulfotomaculum copahuensis Strain CINDEFI1 Isolated from the Geothermal Copahue System, Neuquén, Argentina

    PubMed Central

    Yaakop, Amira Suriaty; Chan, Chia Sing; Urbieta, M. Sofía; Ee, Robson; Tan-Guan-Sheng, Adrian; Donati, Edgardo R.

    2016-01-01

    Desulfotomaculum copahuensis strain CINDEFI1 is a novel spore-forming sulfate-reducing bacterium isolated from the Copahue volcano area, Argentina. Here, we present its draft genome in which we found genes related with the anaerobic respiration of sulfur compounds similar to those present in the Copahue environment. PMID:27540078

  12. Bathymetry of southern Mauna Loa Volcano, Hawaii

    USGS Publications Warehouse

    Chadwick, William W.; Moore, James G.; Garcia, Michael O.; Fox, Christopher G.

    1993-01-01

    Manua Loa, the largest volcano on Earth, lies largely beneath the sea, and until recently only generalized bathymetry of this giant volcano was available. However, within the last two decades, the development of multibeam sonar and the improvement of satellite systems (Global Positioning System) have increased the availability of precise bathymetric mapping. This map combines topography of the subaerial southern part of the volcano with modern multibeam bathymetric data from the south submarine flank. The map includes the summit caldera of Mauna Loa Volcano and the entire length of the 100-km-long southwest rift zone that is marked by a much more pronounced ridge below sea level than above. The 60-km-long segment of the rift zone abruptly changes trend from southwest to south 30 km from the summit. It extends from this bend out to sea at the south cape of the island (Kalae) to 4 to 4.5 km depth where it impinges on the elongate west ridge of Apuupuu Seamount. The west submarine flank of the rift-zone ridge connects with the Kahuku fault on land and both are part of the ampitheater head of a major submarine landslide (Lipman and others, 1990; Moore and Clague, 1992). Two pre-Hawaiian volcanic seamounts in the map area, Apuupuu and Dana Seamounts, are apparently Cretaceous in age and are somewhat younger than the Cretaceous oceanic crust on which they are built.

  13. Comparison of the microbial communities of hot springs waters and the microbial biofilms in the acidic geothermal area of Copahue (Neuquén, Argentina).

    PubMed

    Urbieta, María Sofía; González-Toril, Elena; Bazán, Ángeles Aguilera; Giaveno, María Alejandra; Donati, Edgardo

    2015-03-01

    Copahue is a natural geothermal field (Neuquén province, Argentina) dominated by the Copahue volcano. As a consequence of the sustained volcanic activity, Copahue presents many acidic pools, hot springs and solfataras with different temperature and pH conditions that influence their microbial diversity. The occurrence of microbial biofilms was observed on the surrounding rocks and the borders of the ponds, where water movements and thermal activity are less intense. Microbial biofilms are particular ecological niches within geothermal environments; they present different geochemical conditions from that found in the water of the ponds and hot springs which is reflected in different microbial community structure. The aim of this study is to compare microbial community diversity in the water of ponds and hot springs and in microbial biofilms in the Copahue geothermal field, with particular emphasis on Cyanobacteria and other photosynthetic species that have not been detected before in Copahue. In this study, we report the presence of Cyanobacteria, Chloroflexi and chloroplasts of eukaryotes in the microbial biofilms not detected in the water of the ponds. On the other hand, acidophilic bacteria, the predominant species in the water of moderate temperature ponds, are almost absent in the microbial biofilms in spite of having in some cases similar temperature conditions. Species affiliated with Sulfolobales in the Archaea domain are the predominant microorganism in high temperature ponds and were also detected in the microbial biofilms. PMID:25605537

  14. Elysium Mons Volcano - Detail of Southern Caldera Wall and Floor

    NASA Technical Reports Server (NTRS)

    1998-01-01

    On July 4, 1998--the first anniversary of the Mars Pathfinder landing--Mars Global Surveyor's latest images were radioed to Earth with little fanfare. The images received on July 4, 1998, however, were very exciting because they included a rare crossing of the summit caldera of a major martian volcano. Elysium Mons is located at 25oN, 213oW, in the martian eastern hemisphere. Elysium Mons is one of three large volcanoes that occur on the Elysium Rise-- the others are Hecates Tholus (northeast of Elysium Mons) and Albor Tholus (southeast of Elysium Mons). The volcano rises about 12.5 kilometers (7.8 miles) above the surrounding plain, or about 16 kilometers (9.9 miles) above the martian datum-- the 'zero' elevation defined by average martian atmospheric pressure and the planet's radius.

    Elysium Mons was discovered by Mariner 9 in 1972. It differs in a number of ways from the familiar Olympus Mons and other large volcanoes in the Tharsis region. In particular, there are no obvious lava flows visible on the volcano's flanks. The lack of lava flows was apparent from the Mariner 9 images, but the new MOC high resolution image--obtained at 5.24 meters (17.2 feet) per pixel--illustrates that this is true even when viewed at higher spatial resolution.

    Elysium Mons has many craters on its surface. Some of these probably formed by meteor impact, but many show no ejecta pattern characteristic of meteor impact. Some of the craters are aligned in linear patterns that are radial to the summit caldera--these most likely formed by collapse as lava was withdrawn from beneath the surface, rather than by meteor impact. Other craters may have formed by explosive volcanism. Evidence for explosive volcanism on Mars has been very difficult to identify from previous Mars spacecraft images. This and other MOC data are being examined closely to better understand the nature and origin of volcanic features on Mars.

    The three MOC images, 40301 (red wide angle), 40302 (blue wide angle

  15. Scoria Cone Construction Mechanism, Lathrop Wells Volcano, Southern Nevada

    SciTech Connect

    G. Valentine; D. Krier; F. Perry; G. Heiken

    2005-01-18

    Scoria cones are commonly assumed to have been constructed by the accumulation of ballistically-ejected clasts from discrete and relatively coarse-grained Strombolian bursts and subsequent avalanching such that the cone slopes are at or near the angle of repose for loose scoria. The cone at the hawaiitic Lathrop Wells volcano, southern Nevada, contains deposits that are consistent with the above processes during early cone-building phases; these early deposits are composed mainly of coarse lapilli and fluidal bombs and are partially welded, indicating relatively little cooling during flight. However, the bulk of the cone is comprised of relatively fine-grained (ash and lapilli), planar beds with no welding, even within a few tens of meters of the vent. This facies is consistent with deposition by direct fallout from sustained eruption columns of relatively well-fragmented material, primarily mantling cone slopes and with a lesser degree of avalanching than is commonly assumed. A laterally extensive fallout deposit (up to 20 km from the vent) is inferred to have formed contemporaneously with these later cone deposits. This additional mechanism for construction of scoria cones may also be important at other locations, particularly where the magmas are relatively high in volatile content and where conditions promote the formation of abundant microlites in the rising mafic magma.

  16. Scoria cone construction mechanisms, Lathrop Wells volcano, southern Nevada, USA

    NASA Astrophysics Data System (ADS)

    Valentine, Greg A.; Krier, Don; Perry, Frank V.; Heiken, Grant

    2005-08-01

    Scoria cones are commonly assumed to have been constructed by the accumulation of ballistically ejected clasts from discrete, relatively coarse-grained Strombolian bursts and subsequent avalanching such that the cone slopes are at or near the angle of repose for loose scoria. The cone at the hawaiitic Lathrop Wells volcano, southern Nevada, contains deposits that are consistent with these processes during early cone-building phases; these early deposits are composed mainly of coarse lapilli and fluidal bombs and are partially welded, indicating relatively little cooling during flight. However, the bulk of the cone is composed of relatively fine-grained (ash and lapilli) planar beds with no welding, even within a few tens of meters of the vent. This facies is consistent with deposition by direct fallout from sustained eruption columns of relatively well-fragmented material, primarily mantling cone slopes and with a lesser degree of avalanching than is commonly assumed. A laterally extensive fallout deposit (as much as 20 km from the vent) is inferred to have formed contemporaneously with these later cone deposits. This additional mechanism for construction of scoria cones may also be important at other locations, particularly where the magmas are relatively high in volatile content and where conditions promote the formation of abundant microlites in the rising mafic magma.

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

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    Medicine Lake Volcano (MLV), located in the southern Cascades ˜ 55 km east-northeast of contemporaneous Mount Shasta, has been found by exploratory geothermal drilling to have a surprisingly silicic core mantled by mafic lavas. This unexpected result is very different from the long-held view derived from previous mapping of exposed geology that MLV is a dominantly basaltic shield volcano. Detailed mapping shows that < 6% of the ˜ 2000 km 2 of mapped MLV lavas on this southern Cascade Range shield-shaped edifice are rhyolitic and dacitic, but drill holes on the edifice penetrated more than 30% silicic lava. Argon dating yields ages in the range ˜ 475 to 300 ka for early rhyolites. Dates on the stratigraphically lowest mafic lavas at MLV fall into this time frame as well, indicating that volcanism at MLV began about half a million years ago. Mafic compositions apparently did not dominate until ˜ 300 ka. Rhyolite eruptions were scarce post-300 ka until late Holocene time. However, a dacite episode at ˜ 200 to ˜ 180 ka included the volcano's only ash-flow tuff, which was erupted from within the summit caldera. At ˜ 100 ka, compositionally distinctive high-Na andesite and minor dacite built most of the present caldera rim. Eruption of these lavas was followed soon after by several large basalt flows, such that the combined area covered by eruptions between 100 ka and postglacial time amounts to nearly two-thirds of the volcano's area. Postglacial eruptive activity was strongly episodic and also covered a disproportionate amount of area. The volcano has erupted 9 times in the past 5200 years, one of the highest rates of late Holocene eruptive activity in the Cascades. Estimated volume of MLV is ˜ 600 km 3, giving an overall effusion rate of ˜ 1.2 km 3 per thousand years, although the rate for the past 100 kyr may be only half that. During much of the volcano's history, both dry HAOT (high-alumina olivine tholeiite) and hydrous calcalkaline basalts erupted

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

    USGS Publications Warehouse

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

    2008-01-01

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

  19. The 2012 Copahue eruption: magnitude of gas fluxes and time scale of degassing

    NASA Astrophysics Data System (ADS)

    Varekamp, J. C.; Camfield, L.

    2015-12-01

    Copahue volcano (Argentina, 37.5 S, 71.5 W) erupted in 2000 and 2012 with initial phreato-magmatic blasts, violent Strombolian eruptions of several hours duration, followed by open conduit activity for days to months. The 2012 basal deposits 10 km S of Copahue are mm-sized ashes with hydrothermally altered debris, followed by up to 10cm pancake pumices, while denser cinders fell near the crater in the waning stages. The strombolian plume was ~ 6 km high and satellite images show its trajectory up to 200 km S. The pumices have finely porous rims (0.3mm vesicles) that were probably quenched by hydrothermal fluids and coarse interiors (several mm vesicles) that inflated during eruption. All the products have identical chemical composition and mineralogy, and only vary in degree of vesiculation. The 2012 products are the most mafic of the whole volcanic history of Copahue, with MgO ~ 4.5 %. The quench rim pumice glass contains 1160 ppm Cl while glass inclusions have up to 1800 ppm Cl. Water concentrations are 0.5-2.0 % (by difference with EMPA) and plagioclase hygrometry. Pre-eruptive conditions were 1080 oC and 1-2.5 kb pressure. The magmato-hydrothermal system is leaking fluids into the overlying crater lake and into a river. The hot springs have pH <1 and these fluids are up to 60% magmatic in origin. Annual river flux measurements and non-steady state modeling between 1997 and 2013 constrain the mean hydrothermal Cl flux at 1170 tonnes/month. The 2012 erupted magma mass is about 1012 gr, and from the measured total Cl loss between 2000 and 2012 and mean degassed Cl in the magma the volume of degassing magma is estimated at 1014-1015 grams. Much more magma was degassing than was erupted. Analyses of 226Ra-210Pb constrained the maximum degassing time at 8-10 years prior to the 2012 eruption. Almost all rock samples have 210Pb deficits, and so most gas escaped from the magma into the hydrothermal system. Nonetheless, the top of the magma reservoir accumulated bubbles

  20. Volcanoes

    ERIC Educational Resources Information Center

    Kunar, L. N. S.

    1975-01-01

    Describes the forces responsible for the eruptions of volcanoes and gives the physical and chemical parameters governing the type of eruption. Explains the structure of the earth in relation to volcanoes and explains the location of volcanic regions. (GS)

  1. Volcanoes

    SciTech Connect

    Decker, R.W.; Decker, B.

    1989-01-01

    This book describes volcanoes although the authors say they are more to be experienced than described. This book poses more question than answers. The public has developed interest and awareness in volcanism since the first edition eight years ago, maybe because since the time 120 volcanoes have erupted. Of those, the more lethal eruptions were from volcanoes not included in the first edition's World's 101 Most Notorious Volcanoes.

  2. Volcanoes.

    ERIC Educational Resources Information Center

    Tilling, Robert I.

    One of a series of general interest publications on science topics, this booklet provides a non-technical introduction to the subject of volcanoes. Separate sections examine the nature and workings of volcanoes, types of volcanoes, volcanic geological structures such as plugs and maars, types of eruptions, volcanic-related activity such as geysers…

  3. The Role of Crustal Tectonics in Volcano Dynamics (ROCTEVODY) along the Southern Andes: seismological study with emphasis on Villarrica Volcano

    NASA Astrophysics Data System (ADS)

    Mora-Stock, Cindy; Tassara, Andrés

    2016-04-01

    The Southern Andean margin is intrinsically related to the Liquiñe-Ofqui Fault Zone (LOFZ), a 1000 km-long dextral strike-slip arc-parallel fault on which most of the volcanic centers of the Southern Volcanic Zone (SCVZ) of the Andes are emplaced. At large spatial (102 - 103 km) and temporal (105 - 107 yr) scales, regional tectonics linked to partitioning of the oblique convergence controls the distribution of magma reservoirs, eruption rates and style, as well as the magma evolution. At small scales in space (< 102 km) and time (10‑1 - 102 yr), stress transfer mechanisms between magma reservoirs and seismically-active faults are though to transiently change the regional stress field, thus leading to eruptions and fault (re)activation. However, the mechanisms by which the interaction between (megathrust and crustal) earthquakes and volcanic eruptions actually occur, in terms of generating the relationships and characteristics verified at the long term, are still poorly understood. Since 2007, the Southern Andean margin has presented an increase of its tectonic and eruptive activity with several volcanic crisis and eruptions taking place in association with significant seismicity clusters and earthquakes both in the megathrust and the LOFZ. This increased activity offers a unique opportunity to improve our understanding of the physical relation between contemporary tectono-volcanic processes and the long-term construction of the LOFZ-SVZ system. Taking advantage of this opportunity by means of an integrated analysis of geodetic and seismological data through finite element numerical modeling at the scale of the entire margin and for selected cases is the main goal of project Active Tectonics and Volcanism at the Southern Andes (ACT&VO-SA, see Tassara et al. this meeting). Into the framework of the ACT&VO-SA project, the complementary ROCTEVODY-Villarrica project concentrates on the role that inherited crustal structures have in the volcano dynamics. The focus is

  4. The geothermal system of Caviahue-Copahue Volcanic Complex (Chile-Argentina): New insights from self-potential, soil CO2 degassing, temperature measurements and helium isotopes, with structural and fluid circulation implications.

    NASA Astrophysics Data System (ADS)

    Roulleau, Emilie; Bravo, Francisco; Barde-Cabusson, Stephanie; Pizarro, Marcela; Muños, Carlos; Sanchez, Juan; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; de Cal, Federico; Esteban, Carlos

    2016-04-01

    Geothermal systems represent natural heat transfer engines in a confined volume of rock which are strongly influenced by the regional volcano-tectonic setting controlling the formation of shallow magmatic reservoirs, and by the local faults/fracture network, that permits the development of hydrothermal circulation cells and promote the vertical migration of fluids and heat. In the Southern Volcanic Zone of Chile-Argentina, geothermal resources occur in close spatial relationship with active volcanism along the Cordillera which is primarily controlled by the 1000 km long, NNE Liquiñe-Ofqui Fault Zone (LOFZ), an intra-arc dextral strike-slip fault system, associated with second-order intra-arc anisotropy of overall NE-SW (extensional) and NW-SE orientation (compressional). However there is still a lack of information on how fault network (NE and WNW strinking faults) and lithology control the fluid circulation. In this study, we propose new data of dense self-potential (SP), soil CO2 emanation and temperature (T) measurements within the geothermal area from Caviahue-Copahue Volcanic Complex (CCVC), coupled with helium isotopes ratios measured in fumaroles and thermal springs. We observe that inside the geothermal system the NE-striking faults, characterized by a combination of SP-CO2 and T maxima with high 3He/4He ratios (7.86Ra), promote the formation of high vertical permeability pathways for fluid circulation. Whereas, the WNW-striking faults represent low permeability pathways for hydrothermal fluids ascent associated with moderate 3He/4He ratios (5.34Ra), promoting the infiltration of meteoric water at shallow depth. These active zones are interspersed by SP-CO2- T minima, which represent self-sealed zones (e.g. impermeable altered rocks) at depth, creating a barrier inhibiting fluids rise. The NE-striking faults seem to be associated with the upflow zones of the geothermal system, where the boiling process produces a high vapor-dominated zone close to the

  5. The historical (218 ± 14 aBP) explosive eruption of Tutupaca volcano (Southern Peru)

    NASA Astrophysics Data System (ADS)

    Samaniego, Pablo; Valderrama, Patricio; Mariño, Jersy; van Wyk de Vries, Benjamín; Roche, Olivier; Manrique, Nélida; Chédeville, Corentin; Liorzou, Céline; Fidel, Lionel; Malnati, Judicaëlle

    2015-06-01

    The little known Tutupaca volcano (17° 01' S, 70° 21' W), located at the southern end of the Peruvian arc, is a dacitic dome complex that experienced a large explosive eruption during historical times. Based on historic chronicles and our radiometric data, this eruption occurred 218 ± 14 aBP, probably between 1787 and 1802 AD. This eruption was characterised by a large sector collapse that triggered a small debris avalanche (<1 km3) and an associated pyroclastic eruption whose bulk volume was 6.5-7.5 × 107 m3. Both units were emplaced synchronously and spread onto the plain situated to the northeast of Tutupaca volcano. The spatial and temporal relationship between the debris avalanche and the pyroclastic density current deposits, coupled with the petrological similarity between the juvenile fragments in the debris avalanche, the pyroclastic density current deposits and the pre-avalanche domes, indicates that juvenile magma was involved in the sector collapse. Large amounts of hydrothermally altered material are also found in the avalanche deposit. Thus, the ascent of a dacitic magma, coupled with the fact that the Tutupaca dome complex was constructed on top of an older, altered volcanic sequence, probably induced the destabilisation of the hydrothermally active edifice, producing the debris avalanche and its related pyroclastic density currents. This eruption probably represents the youngest debris avalanche in the Andes and was accompanied by one of the larger explosive events to have occurred in Southern Peru during historical times.

  6. Geochemical constraints on possible subduction components in lavas of Mayon and Taal Volcanoes, Southern Luzon, Philippines

    USGS Publications Warehouse

    Castillo, P.R.; Newhall, C.G.

    2004-01-01

    Mayon is the most active volcano along the east margin of southern Luzon, Philippines. Petrographic and major element data indicate that Mayon has produced a basaltic to andesitic lava series by fractional crystallization and magma mixing. Trace element data indicate that the parental basalts came from a heterogeneous mantle source. The unmodified composition of the mantle wedge is similar to that beneath the Indian Ocean. To this mantle was added a subduction component consisting of melt from subducted pelagic sediment and aqueous fluid dehydrated from the subducted basaltic crust. Lavas from the highly active Taal Volcano on the west margin of southern Luzon are compositionally more variable than Mayon lavas. Taal lavas also originated from a mantle wedge metasomatized by aqueous fluid dehydrated from the subducted basaltic crust and melt plus fluid derived from the subducted terrigenous sediment. More sediment is involved in the generation of Taal lavas. Lead isotopes argue against crustal contamination. Some heterogeneity of the unmodified mantle wedge and differences in whether the sediment signature is transferred into the lava source through an aqueous fluid or melt phase are needed to explain the regional compositional variation of Philippine arc lavas. ?? Oxford University Press 2004; all rights reserved.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  8. Magma Genesis of Sakurajima, the Quaternary post- Aira caldera volcano, southern Kyushu Island, Japan

    NASA Astrophysics Data System (ADS)

    Shibata, T.; Suzuki, J.; Yoshikawa, M.; Kobayashi, T.; Miki, D.; Takemura, K.

    2012-12-01

    Sakurajima volcano is the Quaternary post-caldera volcano of Aira caldera, which was caused by the eruption of huge amount of silicic pyroclastics, situated on Ryukyu arc, southern Kyushu Island, Japan. This volcano is quite active, so it can be considered that the preparation of next caldera-forming eruption with huge amount of silicic magma is proceeding. It is, therefore, expected that the investigation of magma genesis of Sakurajima volcano give us information for the mechanism generating huge amount of silicic magma, which cause the caldera formation. We analyzed major and trace elements with Sr, Nd and Pb isotopic compositions of volcanic rocks from Sakurajima volcano. We sampled (ol) - opx - cpx - pl andesite and dacite from almost all the volcanic units defined by Fukuyama and Ono (1981). In addition to Sakurajima samples, we also studied basaltic rocks erupted at pre-caldera stage of the Aira caldera to estimate the primary magma of Sakurajima volcano. Major and trace element variations generally show linear trends on the Harker diagrams, with the exception of P2O5 and TiO2. Based on the trend of P2O5 vs.SiO2, we divided studied samples low-P (P2O5 < 0.15 wt. %) and high-P (P2O5 > 0.15 wt. %) groups and these groups also display two distinct trends on TiO2-SiO2 diagram. The composition of trace elements shows typical island arc character as depletion of Nb and enrichments of Rb, K and Pb, suggesting addition of aqueous fluids to the mantle wedge. The Zr and Nb concentrations make a liner trend (Zr/Nb = 27) and this trend across from tend of MORB (Zr/Nb = 35) to that of crustal materials (Zr/Nb=17). The Sr, Nd and Pb isotopic compositions broadly plot to on the mixing curve connecting MORB-type mantle and sediments of the Philippine Sea Plate, indicating that the primary magma was generated by partial melting of MORB-type mantle wedge, which was hydrated with fluids derived from the subducted Philippine Sea sediments. But we found that our data plot apart

  9. Tephrochronology of a late quatternary lacustrine record from the monticchio maar (vulture volcano, southern Italy)

    NASA Astrophysics Data System (ADS)

    Narcisi, Biancamaria

    With the aim of defining the chronological framework of the 51 m deep sedimentary sequence (core D) from Lago Grande di Monticchio (Mt Vulture volcano), macroscopic, microscopic and geochemical investigations have been carried out on the 14 thickest (at least 3 cm) tephra layers recorded in the core. The results indicate that the tephras are related to the main late Quaternary explosive events from Ischia, Vesuvius and the Phlegrean Fields districts of the Campanian area. Following these results, a usable time scale has been obtained, according to which the sequence spans the last 70 ka. Beyond the chronological information, this investigation has made it possible: (a) to identify widespread time-parallel markers for reliable correlations in the Central Mediterranean; (b) to collect useful data about past powerful eruptions, particularly from Vesuvius, for a better assessment of volcanic hazards in Central and Southern Italy.

  10. Outline of recent research on ice-volcano interactions in Southern Chile

    NASA Astrophysics Data System (ADS)

    Rivera, A.; Bown, F.; Brock, B. W.; Burger, F.; Carrión, D.; Cisternas, S.; Gacitúa, G.; Oberreuter, J.; Silva, R.; Uribe, J. A.; Wendt, A.; Zamora, R.

    2013-05-01

    Glaciers in Southern Chile (34 - 46°S) are mainly located on top of active volcanoes. The majority of these glaciers have only recently been inventoried and their areal and frontal changes are only partially documented. Most of these glaciers have receded and shrank in recent decades. The main driving factor explaining the glacier retreat is thought to be atmospheric changes, however in some cases the cause is the impact of the volcanic activity. In order to understand better the different driving mechanisms and responses, several surveying campaigns have been conducted to a selected group of ice-capped volcanoes, including the use of an airborne Light Detection and Ranging (LIDAR) system, equipped with visible and thermal infrared cameras, and the use of a helicopter borne radio echo sounding system (Radar). The LIDAR system measured the surface topography of the glaciers at sub metric accuracy, allowing the orthorectification of the simultaneously collected aerial photographs. The radar system has been able to penetrate the total thickness of the ice, mapping the bedrock topography as well as the bed power reflection. The 25 active ice-capped volcanoes analyzed in this work have a total ice area in year 2011 of 500 km2, and despite local differences, generalized area shrinkage and frontal retreats were detected with a total ice area lost of almost 200 km2 in the last 35 years. Among these volcanoes, most of the surveys have been conducted at Volcanes Palomo (34.61°S/70.29°W), Hudson (45.90°S/72.97°W) and Villarrica (39.41°S/71.93°W), where digital elevation models (DEMs) were generated as well as high resolution visible and thermal infrared mosaics. The DEMs comparisons have allowed the estimation of mean ice thinning rates up to 2 m/yr at the glacier ablation areas. A maximum ice thickness of 190 m was measured at Volcán Villarrica, where a total volume of water equivalent of 1.45 km3 was estimated. The strongest volcanic activity impact on glaciers was

  11. Hydrothermal surface alteration in the Copahue Geothermal Field (Argentina)

    SciTech Connect

    Mas, Graciela R.; Mas, Luis C.; Bengochea, Leandro

    1996-01-24

    In the area of the Copahue Geothermal Field, there are five active geothermal manifestations, which mainly consist of fumaroles, hot springs and mud pots. Four of these manifestations are located in Argentina: Las Máquinas, Termas de Copahue, Las Maquinitas and El Anfiteatro, and the fifth on the Chilean side: Chancho Co. All of them present a strong acid sulfate country rock alteration, characterized by the assemblage alunite + kaolinite + quartz + cristobalite + pyrite + sulfur + jarosite, as the result of the base leaching by fluids concentrated in H2SO4 by atmospheric oxidation at the water table in a steam heated environment of H2S released by deeper boiling fluids. Another alteration zone in this area, called COP-2, is a fossil geothermal manifestation which shows characteristics of neutral to alkaline alteration represented mainly by the siliceous sinter superimposed over the acid alteration. The mineralogy and zoning of these alteration zones, and their relation with the hidrothermal solutions and the major structures of the area are analized.

  12. Stable isotope ratios in meteoric recharge and groundwater at Mt. Vulture volcano, southern Italy

    NASA Astrophysics Data System (ADS)

    Paternoster, M.; Liotta, M.; Favara, R.

    2008-01-01

    SummaryA rain gauge network consisting of five sites located at different altitudes, ranging from 320 to 1285 m.a.s.l., was installed at Mt. Vulture volcano (southern Italy). Rain water samples were collected monthly over a two-year period and their isotopic composition (δ 18O and δD) was analyzed. During the same period, circulating groundwater was sampled from 24 springs and wells distributed throughout the study area. Monthly isotopic composition values were used to determine the local meteoric water line (LMWL). Its slope is slightly lower than the relationship defined by Longinelli and Selmo (Longinelli, A., Selmo, E., 2003. Isotopic composition of precipitation in Italy: a first overall map. J. Hydrol. 270, 75-88) for southern Italy. The groundwater samples analyzed were distributed essentially along the LMWL. The weighted local meteoric water line (WLMWL), defined through the mean values weighted by the rainfall amount, however, may define in a short range the meteoric end-member in the local hydrological cycle more precisely. Since most of the groundwater sampling locations do not show seasonal variations in their stable isotope values, the flow system appears to be relatively homogeneous. The mean altitude of the recharge by rainfall infiltration was estimated on the basis of the local vertical isotopic gradient δ 18O. A few springs, which show anomalous isotopic values, reveal more regional circulation systems, associated with tectonic structures responsible for the ascent of deeper water.

  13. A Late Holocene explosive mafic eruption of Villarrica volcano, Southern Andes: The Chaimilla deposit

    NASA Astrophysics Data System (ADS)

    Costantini, L.; Pioli, L.; Bonadonna, C.; Clavero, J.; Longchamp, C.

    2011-03-01

    batches with distinct pre-eruptive degassing and rising histories. Our eruption conceptual model implies the arrival of new magma (represented in the deposit by P1 clasts) into a small, outgassed magma body which was accumulated at shallow level (mainly represented by P2 clasts). A new Chaimilla-type eruption could significantly affect the communities that have recently developed around Villarrica volcano and subsist mainly on tourism and forestry. As a result, a better understanding of the dynamics and evolution of the Chaimilla eruption is necessary for the identification of potential hazard scenarios at Villarrica volcano and, ultimately, for the risk mitigation of this populated area of Southern Chile.

  14. Geodetic Measurements and Modelling at Neapolitan Volcanoes(Southern Italy): Somma-Vesuvius and Campi Flegrei

    NASA Astrophysics Data System (ADS)

    de Natale, G.; Troise, C.; Pingue, F.; Obrizzo, F.

    2004-12-01

    We show the recent results about geodetic observations and modelling at two very explosive and densely populated volcanoes in Southern Italy, namely Somma-Vesuvius and Campi Flegrei caldera. The two areas, characterised by the highest volcanic risk in the World because of the density of population and exposed value, are among the best monitored ones in the World. Geodetic monitoring at these areas started more than 30 years ago, and was progressively improved in the last decade, including dense networks making use of both terrestrial and space techniques. The monitored period includes two strong unrests at Campi Flegrei caldera, not followed by eruptions, characterised by uplift of up to 3 m in few years, with rates up to 1 m/year, and intercurring subsidence with rates up to .08 m/year. Somma Vesuvius is on the contrary characterised, in the last 30 years, by a marked stability, except for a very localised subsidence at the young active center (Vesuvius) and a peculiar ring-like subsidence all around the volcanic edifice. The fast uplift and subsidence at Campi Flegrei has been modelled as due to shallow inflation sources and a dominant effect of passive slip along the ring faults bordering the collapsed area. Numerical modelling taking carefully into account the geometry of ring faults gives an accurate description of observed displacements. At Somma-Vesuvius, subsidence of Vesuvius cone is modelled in terms of gravitationally-induced slip along the contact limits between the older caldera and the younger active edifice. The ring-like subsidence around the whole edifice is modelled in terms of normal fault-like behaviour of the contacts among the loaded basement and the superimposed volcanic edifice, subject to the extensional tectonic stress of the area. Both models of ground deformations at the two areas appear very consistent with the behaviour of local volcano-tectonic seismicity, and enlighten the very important role played by volcano-tectonic structures in

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  16. Role of cryptic amphibole crystallization in magma differentiation at Hudson volcano, Southern Volcanic Zone, Chile

    NASA Astrophysics Data System (ADS)

    Kratzmann, David J.; Carey, Steven; Scasso, Roberto A.; Naranjo, Jose-Antonio

    2010-02-01

    Hudson volcano (Chile) is the southern most stratovolcano of the Andean Southern Volcanic Zone and has produced some of the largest Holocene eruptions in South America. There have been at least 12 recorded Holocene explosive events at Hudson, with the 6700 years BP, 3600 years BP, and 1991 eruptions the largest of these. Hudson volcano has consistently discharged magmas of similar trachyandesitic and trachydacitic composition, with comparable anhydrous phenocryst assemblages, and pre-eruptive temperatures and oxygen fugacities. Pre-eruptive storage conditions for the three largest Holocene events have been estimated using mineral geothermometry, melt inclusion volatile contents, and comparisons to analogous high pressure experiments. Throughout the Holocene, storage of the trachyandesitic magmas occurred at depths between 0.2 and 2.7 km at approximately ~972°C (±25) and log fO2 -10.33-10.24 (±0.2) (one log unit above the NNO buffer), with between 1 and 3 wt% H2O in the melt. Pre-eruptive storage of the trachydacitic magma occurred between 1.1 and 2.0 km, at ~942°C (±26) and log fO2 -10.68 (±0.2), with ~2.5 wt% H2O in the melt. The evolved trachyandesitic and trachydacitic magmas can be derived from a basaltic parent primarily via fractional crystallization. Entrapment pressures estimated from plagioclase-hosted melt inclusions suggest relatively shallow levels of crystallization. However, trace element data (e.g., Dy/Yb ratio trends) suggests amphibole played an important role in the differentiation of the Hudson magmas, and this fractionation is likely to have occurred at depths >6 km. The absence of a garnet signal in the Hudson trace element data, the potential staging point for differentiation of parental mafic magmas [i.e., ~20 km (e.g., Annen et al. in J Petrol 47(3):505-539, 2006)], and the inferred amphibolite facies [~24 km (e.g., Rudnick and Fountain in Rev Geophys 33:267-309, 1995)] combine to place some constraint on the lower limit of depth of

  17. Spatiotemporal gravity variations to look deep into the southern flank of Etna volcano

    NASA Astrophysics Data System (ADS)

    Greco, Filippo; Currenti, Gilda; Del Negro, Ciro; Napoli, Rosalba; Budetta, Gennaro; Fedi, Maurizio; Boschi, Enzo

    2010-11-01

    A 14-year-long microgravity data set (October 1994 to September 2007) collected along a 24-km east-west trending profile of 19 stations was analyzed to detect underground mass redistributions related to the volcanic activity involving the southern flank of Mt Etna (Italy). A multiresolution wavelet analysis was applied to separate the volcano-related anomalies from the unwanted components. The residual image having both spatial extension and temporal duration evidenced two complete gravity increase/decrease cycles mainly affecting the central and eastern stations of the profile. The first gravity increase (early 1995 to the end of 1996) and decrease (end of 1996 to late in 1998) cycle reached a maximum amplitude of approximately 90 μGal. The second gravity increase (mid-1999 to mid-2000) and decrease (mid-2000 to early-2004) cycle attained an amplitude of about 80 μGal. After about 5 years of a persistent negative gravity anomaly, a new semicycle started at the end of 2006 and continued during the last survey carried out in September 2007. The density changes, modeled over time since 1994 using a Quadratic Programming algorithm, are mainly located at a depth of 2-4 km bsl in a region recognized to be a preferential pathway of magma rising and an intermediate zone of magma storage/withdrawal. The computed positive mass variations of about 105 × 109 kg were interpreted as magma accumulation, while negative mass changes of about -120 × 109 kg were associated with either magma drainage or opening of new voids by tectonic stresses within a source volume, where tensional earthquakes occurred.

  18. Variable Sources and Differentiation of Lavas from the Copahue-Caviahue Eruptive Complex, Neuquen Argentina

    NASA Astrophysics Data System (ADS)

    Todd, E.; Ort, M. H.

    2012-12-01

    Caldera collapse (˜180 km2) associated with a large Pliocene pyroclastic eruption and subsequent glacial erosion exposed an extensive and complex cross-section of pre-caldera volcanic history (at least 5 My) at the Copahue-Caviahue Eruptive Center (CCEC) in the Andean Southern Volcanic Zone (SVZ) of Argentina. Lava flows in wall exposures range from olivine-rich basaltic andesite to trachyte, are typically horizontal, vary in abundance and thickness at different wall exposures, and rarely correlate with flows in adjacent sections, although some lava and pyroclastic deposits from adjacent sections are similar in petrography, mineral assemblage, and geochemistry. Bulk-rock geochemical and isotopic data indicate at least two distinct primary melt types contributed to pre-caldera CCEC volcanism, and their differentiates produced a high-K and a low-K series. Incompatible element and isotope systematics suggest they are not related by differentiation of a common parental melt, and less-evolved examples of both types occur throughout the pre-caldera stratigraphic section, suggesting long-lived recharge of the local system by variably-sourced magmas. Petrographic and mineral chemistry evidence indicates that mixing of dissimilar magma types produced compositionally intermediate magmas. The location of the CCEC, rear of the volcanic front (VF), yet trenchward of regional backarc basin (BAB) volcanism, is reflected by the composition of CCEC lavas, which are transitional between local VF and BAB types. Thus, contrasting low- and high-K CCEC magmas in the SVZ rear-arc may reflect local focusing of VF-like (low-K) and BAB-like (high-K) melts.

  19. The evolution of the Monte Vulture volcano (Southern Italy): Inferences from volcanological, geological and deep dipole electrical soundings data

    NASA Astrophysics Data System (ADS)

    La Volpe, L.; Patella, D.; Rapisardi, L.; Tramacere, A.

    1984-10-01

    The activity of Monte Vulture started in the Middle Pleistocene; stratigraphic evidence suggests that the volcanic events may have occurred in the following succession: (1) formation of widespread pyroclastic pumice deposits; (2) sporadic and localized explosive and minor extrusive eruptions; (3) highly explosive eruptions with the formation of some tuff cones and of the oldest part of the Monte Vulture central volcano; and (4) activity at the central volcano, initially mainly explosive and successively increasingly effusive. The western part of the composite volcano, and probably also its summit part were affected by caldera collapses. The volcanic activity ended with hydromagmatic explosion, which formed two explosion craters. Monte Vulture was built up on the external units of the Southern Apennines at the western border of the foretrough. The upper part of the sedimentary substratum consists mainly of clayey formations of the Lagonegro and Sannitic units. Beneath these terrains radiolarites and cherty-limestones of the Lagonegro units outcrop west of Monte Vulture. Rocks of the Apulia carbonate platform were drilled east of the volcano. Deep dipole electrical soundings showed a resistant basement at a depth ranging from 0.2 km down to 4.3 km beneath Monte Vulture. Volcanological, geological and geoelectrical data allow us to hypothesize that: (a) the magma chamber could be located at the boundary between the rigid resistant basement and the overlying conductive plastic terrains; (b) the Apulia carbonate platform forms a structural high beneath the Monte Vulture; and (c) the overthrusting of the Lagonegro units on the Apulia platform may be located beneath the floors of the calderas of Monte Vulture.

  20. Young volcanoes in the Chilean Southern Volcanic Zone: A statistical approach to eruption prediction based on time series

    NASA Astrophysics Data System (ADS)

    Dzierma, Y.; Wehrmann, H.

    2010-03-01

    Forecasting volcanic activity has long been an aim of applied volcanology with regard to mitigating consequences of volcanic eruptions. Effective disaster management requires both information on expected physical eruption behaviour such as types and magnitudes of eruptions as typical for the individual volcano, usually reconstructed from deposits of past eruptions, and the likelihood that a new eruption will occur within a given time. Here we apply a statistical procedure to provide a probability estimate for future eruptions based on eruption time series, and discuss the limitations of this approach. The statistical investigation encompasses a series of young volcanoes of the Chilean Southern Volcanic Zone. Most of the volcanoes considered have been active in historical times, in addition to several volcanoes with a longer eruption record from Late-Pleistocene to Holocene. Furthermore, eruption rates of neighbouring volcanoes are compared with the aim to reveal possible regional relations, potentially resulting from local to medium-scale tectonic dynamics. One special focus is directed to the two currently most active volcanoes of South America, Llaima and Villarrica, whose eruption records comprise about 50 historical eruptions over the past centuries. These two front volcanoes are considered together with Lanín Volcano, situated in the back-arc of Villarrica, for which the analysis is based on eight eruptions in the past 10 ka. For Llaima and Villarrica, affirmed tests for independence of the repose times between successive eruptions permit to assume Poisson processes; which is hampered for Lanín because of the more limited availability of documented eruptions. The assumption of stationarity reaches varying degrees of confidence depending on the time interval considered, ameliorating towards the more recent and hence probably more complete eruption record. With these pre-requisites of the time series, several distribution functions are fit and the goodness of

  1. Isotopic and trace element geochemistry of lavas from the northern Mariana and southern volcano arcs

    SciTech Connect

    Lin Pingnan.

    1989-01-01

    Samples from submarine volcanoes and islands were analyzed for concentrations of K, Rb, Sr, Ba, REE, {sup 87}Sr/{sup 86}Sr and some selected samples for {sup 143}Nd/{sup 144}Nd. These data show strong variations along the arc, being relatively depleted in the tholeiitic and low-K calc-alkaline volcanoes of the Volcano Arc (VA) and the Mariana Central Island Province (CIP). All of the Mariana Northern Seamount Province (NSP) and Volcano arc Iwo Jima (IJ) are enriched in LIL and LREE, particularly in the northern half, where the lavas have strong shoshonitic affinities. Chemical characteristics of these lavas suggest source- or melt-mixing, with the NSP shoshonites being derived from a LIL- and LREE-enriched OIB-like source or melt, while Mariana CIP and Volcano Arc melts are derived from a depleted MORB-like mangle that has been recharged with K, Rb, Sr and Ba by hydrous fluids. Neodymium and strontium isotopic data reveal {var epsilon}{sub Nd} values ranging from +2.4 to +9.5 and {sup 87}Sr/{sup 86}Sr from 0.70320 to 0.70405. Anomalous trends of {sup 87}Sr/{sup 86}Sr and Ba/La found in some S-NSP lavas suggest that the addition of a sedimentary component may be superimposed on the two component mixing. The lavas from the Mariana and Volcano arcs, therefore, are interpreted as resulting from mixing of at least three components. The bulk of the lavas derive from an OIB-like mantle source (or melt) mixing with various proportions of a metasomatized depleted mantle source (or melt). These hybrid sources may be contaminated with minor amounts of subducted sediment and fluxed by multistage-fractionated metasomatic fluid which is derived from subducted sediment and slab after the mixing of the first two components.

  2. SMALL-VOLUME BASALTIC VOLCANOES: ERUPTIVE PRODUCTS AND PROCESSES, AND POST-ERUPTIVE GEOMORPHIC EVOLUTION IN CRATER FLAT (PLEISTOCENE), SOUTHERN NEVADA

    SciTech Connect

    G.A. Valentine; F.V. Perry; D. Krier; G.N. Keating; R.E. Kelley; A.H. Cogbill

    2006-04-04

    Five Pleistocene basaltic volcanoes in Crater Flat (southern Nevada) demonstrate the complexity of eruption processes associated with small-volume basalts and the effects of initial emplacement characteristics on post-eruptive geomorphic evolution of the volcanic surfaces. The volcanoes record eruptive processes in their pyroclastic facies ranging from ''classical'' Strombolian mechanisms to, potentially, violent Strombolian mechanisms. Cone growth was accompanied, and sometimes disrupted, by effusion of lavas from the bases of cones. Pyroclastic cones were built upon a gently southward-sloping surface and were prone to failure of their down-slope (southern) flanks. Early lavas flowed primarily southward and, at Red and Black Cone volcanoes, carried abundant rafts of cone material on the tops of the flows. These resulting early lava fields eventually built platforms such that later flows erupted from the eastern (at Red Cone) and northern (at Black Cone) bases of the cones. Three major surface features--scoria cones, lava fields with abundant rafts of pyroclastic material, and lava fields with little or no pyroclastic material--experienced different post-eruptive surficial processes. Contrary to previous interpretations, we argue that the Pleistocene Crater Flat volcanoes are monogenetic, each having formed in a single eruptive episode lasting months to a few years, and with all eruptive products having emanated from the area of the volcanoes main cones rather than from scattered vents. Geochemical variations within the volcanoes must be interpreted within a monogenetic framework, which implies preservation of magma source heterogeneities through ascent and eruption of the magmas.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  4. Geochemistry and Magmagenesis of the Early May 2008 Rhyolitic Magma Erupted by Chaiten Volcano, Southern Andes Volcanic Zone

    NASA Astrophysics Data System (ADS)

    Munoz, J. O.; Basualto, D.; Moreno, H.; Peña, P.; Mella, M.

    2008-12-01

    Chaiten volcano, located in the southern portion of the Southern Andes Volcanic Zone, is a 2 km diameter Holocene obsidian rhyolitic dome inside a 3 km wide caldera formed by an Upper Pleistocene basaltic to andesitic sequence. Chaiten volcano started a plinian eruption on May 1 evolving to subplinian and weak strombolian with time. Eruption has produced a significant evolution of craters geometry, volume of pyroclastic materials, gas and water emissions, large amount of fall out ash, new rhyolitic dome that is still growing, minor pyroclastic flows to the north, lateral blast to the east, and several lahars and mud flows mainly to the south along the river partially burying the Chaiten city. Six glassy, fibrous and banded, highly porous, crystal poor (zoned and twinned plagioclase, hornblende, orthopyroxene and magnetite) rhyolitic pumice and obsidian (including explosion breccias with andesitic to basaltic country rock fragments)fragments and three ash samples (also crystal poor including cristoballite, quartz, feldspars and biotite) representative of the early stage of the explosive eruption have major, trace and REE whole rock geochemical composition indicating an important crustal input in the magmagenesis (high SiO2=73-75, low Al2O3=12.75-14.80, MgO=0.1-0.6, CaO=1.4-1.9, TiO2=0.15-0.28, S=0.01-0.13, moderated K2O=2,7-3.0, Na2O=3.9-4.8 and Rb=95-121ppm, high Ba= 619-665 and Cs=5.71-7.75 and low Sr =142-161, Nb=8.00- 8.75, Y=13-14, Zr=106-121 and La/Yb=20-23 ratios, depleted HREE and HREE patterns and Eu moderate negative anomaly), as also does the previously documented <9,370 yBP rhyolitic pumice and obsidian dome, the last also showing crustal Sr, Nd and Pb isotopic signature (Lopez et al., 1993, Stern et al., 2002, Naranjo and Stern, 2004). Early May samples are depleted in MHEE and HREE and have higher La/Yb (20- 23), Rb/Ba (0.15-0.18), Ba/Sr (3.8-4.7) and Rb/Sr (0.65-0.85) ratios compare to basaltic to andesitic lavas from the Michinmahuida volcano

  5. DESERT PAVEMENTS AND SOILS ON BASALTIC PYROCLASTIC DEPOSITS AT LATHROP WELLS AND RED CONE VOLCANOES, SOUTHERN NEVADA ABSTRACT

    SciTech Connect

    G.A. Valentine; C.D. Harrington

    2005-08-26

    Formation of desert pavement and accretionary soils are intimately linked in arid environments such as the Mojave Desert. Well-sorted fallout scoria lapilli at Lathrop Wells (75-80 ky) and Red Cone ({approx}1 Ma) volcanoes (southern Nevada) formed an excellent starting material for pavement, allowing infiltration of eolian silt and fine sand that first clogs the pore space of underlying tephra and then aggrades and develops vesicular A (Av) horizons. Variations in original pyroclast sizes provide insight into minimum and maximum clast sizes that promote pavement and soil formation: pavement becomes ineffective when clasts can saltate under the strongest winds, while clasts larger than coarse lapilli are unable to form an interlocking pavement that promotes silt accumulation (necessary for Av development). Contrary to predictions that all pavements above altitudes of {approx}400 m would have been ''reset'' in their development after late Pleistocene vegetation advances (about 15 ka), the soils and pavements show clear differences in maturity between the two volcanoes. This indicates that either the pavements/soils develop slowly over many 10,000's of years and then are very stable, or that, if they are disrupted by vegetation advances, subsequent pavements are reestablished with successively more mature characteristics.

  6. DESERT PAVEMENTS AND SOILS ON BASALTIC PYROCLASTIC DEPOSITS AT LATHROP WELLS AND RED CONE VOLCANOES, SOUTHERN NEVADA

    SciTech Connect

    G.A. Valentine; C.D. Harrington

    2005-08-10

    Formation of desert pavement and accretionary soils are intimately linked in arid environments such as the Mojave Desert. Well-sorted fallout scoria lapilli at Lathrop Wells (75-80 ky) and Red Cone ({approx}1 Ma) volcanoes (southern Nevada) formed an excellent starting material for pavement, allowing infiltration of eolian silt and fine sand that first clogs the pore space of underlying tephra and then aggrades and develops vesicular A (Av) horizons. Variations in original pyroclast sizes provide insight into minimum and maximum clast sizes that promote pavement and soil formation: pavement becomes ineffective when clasts can saltate under the strongest winds, while clasts larger than coarse lapilli are unable to form an interlocking pavement that promotes silt accumulation (necessary for Av development). Contrary to predictions that all pavements above altitudes of {approx}400 m would have been ''reset'' in their development after late Pleistocene vegetation advances (about 15 ka), the soils and pavements show clear differences in maturity between the two volcanoes. This indicates that either the pavement soils develop slowly over many 10,000's of years and then are very stable, or that, if they are disrupted by vegetation advances, subsequent pavements are reestablished with successively more mature characteristics.

  7. Trace element and isotopic variations from Mt. Vulture to Campanian volcanoes: constraints for slab detachment and mantle inflow beneath southern Italy

    NASA Astrophysics Data System (ADS)

    de Astis, G.; Kempton, P. D.; Peccerillo, A.; Wu, T. W.

    2006-03-01

    New Sr-Nd-Pb isotopic ratios and trace element data for volcanic mafic rocks outcropping along a E-W transect in southern Italy, from Mt. Vulture to Neapolitan volcanoes, are reported. The variation of LILE/HFSE, HFSE/HFSE and radiogenic isotopes along this transect indicates that all of these volcanoes contain both intra-plate and subduction-related signatures, with the former decreasing from Mt. Vulture to Campanian volcanoes. New data are also reported for the Paleocene alkaline rocks from Pietre Nere (Apulia foreland), which show isotopic ratios mostly overlapping the values for Mediterranean intra-plate volcanoes as well as the Eocene-Oligocene alkaline mafic lavas from the northern Adria plate. Pietre Nere provides evidence for an OIB mantle composition of FOZO-type, free of subduction influences, that is present beneath the Adria plate (Africa) before its collision with Europe. After this collision, and formation of the southern Apennines, westward inflow of mantle from the Adria plate to the Campanian area occurred, as a consequence of slab break off. Interaction of subduction components with inflowing Adria mantle generated hybrid sources beneath the Vulture-Campania area, which can explain the compositional features of both Mt. Vulture and the Campanian mafic rocks. Therefore, mafic magmas from these volcanoes represent variable degrees of mixing between different mantle components.

  8. Calbuco volcano (Southern Chile) Eruption 22-23 April 2015: pyroclastic fall deposits and preliminary petrological study

    NASA Astrophysics Data System (ADS)

    Morgavi, Daniele; Romero, Jorge; Arzilli, Fabio; Daga, Romina; Caselli, Alberto; Reckziegel, Florencia; Viramonte, Jose; Polacci, Margherita; Burton, Mike; Perugini, Diego

    2016-04-01

    After 54 years since its last major eruption in 1961, Calbuco volcano (Ensenada, Southern Chile) reawakened with few hours of warning on 22 April 2015 at 18:05 local time. The main explosive eruption consisted of two eruption pulses (lasting ~1.5 and ~6 hours each one) on 22 and 23 April, producing stratospheric (>15 km height) eruption columns. The tephra fall affected mainly the area northeast of the volcano and the finest ash was deposited over Southern Chile and Patagonia Argentina. We studied the tephra fall deposits of both pulses in terms of stratigraphy, distribution, volume, emplacement dynamics and eruption source parameters. Here, we show field observations made from 5 to 470 km downwind and we distinguish five layers (Layers A, B, B1, C and D) representing different stages of the eruption evolution. The total calculated bulk tephra fall deposit volume is 0.27±0.007 km3 (0.11-0.13 km3 dense rock equivalent). The 38% of it was erupted during the first phase and 62% during the second pulse. This eruption was a magnitude 4.45 event (VEI 4 eruption) of Subplinian type. The erupted materials correspond to a porphyritic basaltic-andesite (54.40-57.2 wt. of % SiO2). It produced two types of pumice clasts: high density pumice (HDP), poorly vesiculated and crystal-rich (up to 40 % crystals by volume), and lower density pumice (LDP) characterized by a slightly lower crystallinity and higher vesicle fraction. The textures include phenocrysts in a glassy groundmass with a minor presence of microlites. The mineralogical assemblage of pumices consists of plagioclase (Pl), orthopyroxene (Opx), clinopyroxene (Cpx), Ti-magnetite, and sanidine (Sa) as accessory mineral.

  9. Eruption dynamics of the 22-23 April 2015 Calbuco Volcano (Southern Chile): Analyses of tephra fall deposits

    NASA Astrophysics Data System (ADS)

    Romero, J. E.; Morgavi, D.; Arzilli, F.; Daga, R.; Caselli, A.; Reckziegel, F.; Viramonte, J.; Díaz-Alvarado, J.; Polacci, M.; Burton, M.; Perugini, D.

    2016-05-01

    After 54 years since its last major eruption in 1961, Calbuco Volcano (Ensenada, Southern Chile) reawakened with few hours of warning on 22 April 2015 at 18:05 local time. The main explosive eruption consisted of two eruption pulses (lasting ~ 1.5 and 6 h each one) on 22 and 23 April, producing stratospheric (> 15 km height) eruption columns. The erupted materials correspond to porphyritic basaltic andesite (~ 55 wt.% of SiO2). The tephra fall affected mainly the area northeast of the volcano and the finest ash was deposited over Southern Chile and Patagonia Argentina. We studied the tephra fall deposits of both pulses in terms of stratigraphy, distribution, volume, emplacement dynamics and eruption source parameters. Here, we show field observations that have been made 5-470 km downwind and distinguish five layers (Layers A, B, B1, C and D) representing different stages of the eruption evolution: eruption onset (Layer A; pulse 1), followed by the first paroxysmal event (Layer B; pulse 1), in some places interbedded by layer B1, tentatively representing the sedimentation of a secondary plume during the end of pulse 1. We recognized a second paroxysm (Layer C; pulse 2) followed by the waning of the eruption (Layer D; pulse 2). The total calculated bulk tephra fall deposit volume is 0.27 ± 0.007 km3 (0.11-0.13 km3 dense rock equivalent), 38% of which was erupted during the first phase and 62% during the second pulse. This eruption was a magnitude 4.45 event (VEI 4 eruption) of subPlinian type.

  10. Discovery and Description of Extinct Asphalt Volcanoes Along the Southern California Margin

    NASA Astrophysics Data System (ADS)

    Valentine, D. L.; Reddy, C.; Ventura, G. T.; Nelson, R. K.

    2007-12-01

    Asphalt volcanism is increasingly being recognized as an important process at cold seeps, linking ancient subsurface carbon reservoirs with more rapid biogeochemical processes at the surface. Here we describe two extinct asphalt volcanoes discovered off the coast of Santa Barbara, CA, using the DSV Alvin during the July 2007 SEEPS (Studies on the Ecology and Evolution of Petroleum Seeps) cruise. These structures are located approximately 10 kilometers offshore and 2 kilometers apart from each other, at a water depth of 150 to 200 meters. The volcanoes occur as asphalt mounds closely associated with sediment-laden depressions, suggesting extrusion of liquid petroleum coupled with localized subsidence or gas blowout. The volcanoes range from 10 to 30 meters in height off the sea floor and may extend below the present level of sediment cover. No active seepage was observed during approximately 10 hours of visual and video surveys from the DSV Alvin, but the volcanoes appear to serve as an oasis for benthic life when compared to the surrounding sediment. Four asphalt samples were collected throughout each site during these surveys and all show remarkable similarity in their structure and chemical composition. Organic carbon comprises 50 percent of the mass for each sample, with sulfur, hydrogen and nitrogen comprising another 10 percent in aggregate. Inclusions of fine-grained sediment and microfossils comprise much of the residual mass and are being used in an attempt to determine the timing of the eruptive events. Each sample was analyzed for the stable isotope composition of carbon, nitrogen and sulfur, and results are consistent with a petroleum source from the Miocene-age Monterey Formation. Analysis of biomarkers using comprehensive two-dimensional gas chromatography yields a suite of hopanes and steranes also consistent with petroleum from the Monterey Formation, but with anomalously high concentrations of bisnorhopane. To our knowledge, this is the first report

  11. Timing of maximum glacial extent and deglaciation from HualcaHualca volcano (southern Peru), obtained with cosmogenic 36Cl.

    NASA Astrophysics Data System (ADS)

    Alcalá, Jesus; Palacios, David; Vazquez, Lorenzo; Juan Zamorano, Jose

    2015-04-01

    Andean glacial deposits are key records of climate fluctuations in the southern hemisphere. During the last decades, in situ cosmogenic nuclides have provided fresh and significant dates to determine past glacier behavior in this region. But still there are many important discrepancies such as the impact of Last Glacial Maximum or the influence of Late Glacial climatic events on glacial mass balances. Furthermore, glacial chronologies from many sites are still missing, such as HualcaHualca (15° 43' S; 71° 52' W; 6,025 masl), a high volcano of the Peruvian Andes located 70 km northwest of Arequipa. The goal of this study is to establish the age of the Maximum Glacier Extent (MGE) and deglaciation at HualcaHualca volcano. To achieve this objetive, we focused in four valleys (Huayuray, Pujro Huayjo, Mollebaya and Mucurca) characterized by a well-preserved sequence of moraines and roches moutonnées. The method is based on geomorphological analysis supported by cosmogenic 36Cl surface exposure dating. 36Cl ages have been estimated with the CHLOE calculator and were compared with other central Andean glacial chronologies as well as paleoclimatological proxies. In Huayuray valley, exposure ages indicates that MGE occurred ~ 18 - 16 ka. Later, the ice mass gradually retreated but this process was interrupted by at least two readvances; the last one has been dated at ~ 12 ka. In the other hand, 36Cl result reflects a MGE age of ~ 13 ka in Mollebaya valley. Also, two samples obtained in Pujro-Huayjo and Mucurca valleys associated with MGE have an exposure age of 10-9 ka, but likely are moraine boulders affected by exhumation or erosion processes. Deglaciation in HualcaHualca volcano began abruptly ~ 11.5 ka ago according to a 36Cl age from a polished and striated bedrock in Pujro Huayjo valley, presumably as a result of reduced precipitation as well as a global increase of temperatures. The glacier evolution at HualcaHualca volcano presents a high correlation with

  12. The 2011-2012 eruption of Cordón Caulle volcano (Southern Andes): Evolution, crisis management and current hazards

    NASA Astrophysics Data System (ADS)

    Silva Parejas, C.; Lara, L. E.; Bertin, D.; Amigo, A.; Orozco, G.

    2012-04-01

    A new kind of integrated approach was for first time achieved during the eruptive crisis of Cordón Caulle volcano (Southern Andes, 40.59°S, 72.12°W) in Chile. The monitoring network of SERNAGEOMIN around the volcano detected the increasing precursory seismicity, alerting the imminence of an eruption about 5 hours before its onset, on June 4, 2011. In addition, SERNAGEOMIN generated daily forecasts of tephra dispersal and fall (ASHFALL advection-diffusion model), and prepared simulations of areas affected by the possible occurrence of lahars and pyroclastic flows. Models were improved with observed effects on the field and satellite imagery, resulting in a good correlation. The information was timely supplied to the authorities as well as recommendations in order to better precise the vulnerable areas. Eruption has initially occurred from a couple of overlapped cones located along the eastern fault scarp of the Pleistocene-Holocene extensional graben of Cordón Caulle. Eruptive products have virtually the same bulk composition as those of the historical 1921 and 1960 eruptions, corresponding to phenocryst-poor rhyodacites (67-70 % SiO2). During the first eruptive stage, a ca. 15-km strong Plinian column lasting 27 hours emitted 0.2-0.4 km3 of magma (DRE). Thick tephra deposits have been accumulated in Chile and Argentina, whereas fine particles and aerosols dispersion disrupted air navigation across the Southern Hemisphere. The second ongoing eruptive stage, which started in mid-June, has been characterized by lava emission already covering a total area comparable to the 1960 lava flows with a total estimated volume <0.25 km3 (at the end of December 2011). Weak but persistent plumes have caused preventive flight suspensions in Chile and Argentina until the end of the year. Main current hazards at Cordón Caulle volcano are fine tephra fallout, secondary lahars, minor explosions and lava flow front collapse. Even if this case can be considered successful from the

  13. Managing the effects of accelerated glacial melting on volcanic collapse and debris flows: Planchon-Peteroa Volcano, Southern Andes

    NASA Astrophysics Data System (ADS)

    Tormey, Daniel

    2010-11-01

    Glaciated mountains are among the most sensitive environments to climatic changes, and recent work has shown that large-scale glacial melting, including at the end of the Pleistocene, caused a significant increase in the incidence of large volcanic sector collapse and debris flows on then-active volcanoes. With current accelerated rates of glacial melting, glaciated active volcanoes are at an increasing risk of sector collapse, debris flow and landslide. These catastrophic events are Earth's most damaging erosion phenomenon, causing extensive property damage and loss of life. This paper illustrates these effects in well-studied settings, focusing on the end-Pleistocene to Holocene glaciovolcanic growth and destruction of the cone of the active volcano Planchon-Peteroa in the Andean Southern Volcanic Zone at latitude 35° 15' S, along the border between Chile and Argentina. The development of the volcano over the last 14,000 years illustrates how glacial melting and magmatic activity can trigger landslides and sector collapses. Planchon had a large sector collapse that produced a highly mobile and erosive debris avalanche 11,000 years BP, and other slope instabilities during the end-Pleistocene/early Holocene deglaciation. The summit amphitheater left after the sector collapse was subject to alternating periods of glaciation and melting-induced lake formation. Breaching of the moraine dams then formed lahars and landslides originating at the western edge of the summit amphitheater, and the deposits are preserved along the western flank of the volcano. Deep incision of moraine deposits further down the western slope of the volcano indicates that the lahars and landslides were water-rich and had high erosive power. As illustrated by Planchon-Peteroa, the interplay among glacial growth and melting, magmatic activity, and slope stability is complex, but must be accounted for in volcanic hazard assessment. Planchon-Peteroa currently has the southernmost temperate zone

  14. Kinematics and age of Early Tertiary trench parallel volcano-tectonic lineaments in southern Mexico: Tectonic implications

    NASA Astrophysics Data System (ADS)

    Martini, M.; Ferrari, L.; Lopez Martinez, M.; Cerca Martinez, M.; Serrano Duran, L.

    2007-05-01

    We present new geological, structural, and geochronological data that constrain the timing and geometry of Early Tertiary strike slip deformation in southwestern Mexico and its relation with the concurrent magmatic activity. Geologic mapping in Guerrero and Michoacan States documented two regional WNW trending volcano-tectonic lineaments sub parallel to the present trench. The southernmost lineament runs for ~140 km from San Miguel Totolapan area (NW Guerrero) to Sanchiqueo (SE Michoacan), and passes through Ciudad Altamirano. Its southeastern part is marked by the alignment of at least eleven silicic to intermediate major domes as well as by the course of the Balsas River. The northwestern part of the lineament is characterized by ductile left lateral shear zones in Early Tertiary plutonic rocks observed in the Rio Chiquito valley. Domes near Ciudad Altamirano are unaffected by ductile shearing and yielded a ~42 Ma 40Ar/39Ar age, setting a minimum age for this deformation. The northern volcano-tectonic lineament runs for ~190 km between the areas of Huitzuco in northern Guerrero and the southern part of the Tzitzio fold in eastern Michoacan. The Huautla, Tilzapotla, Taxco, La Goleta and Nanchititla silicic centers (all in the range 37-34 Ma) are emplaced along this lineament, which continues to the WNW trough a mafic dike swarm exposed north of Tiquicheo (37-35 Ma) and the Purungueo subvolcanic body (~42 Ma). These rocks, unaffected by ductile shearing, give a minimum age of deformation similar to the southern Totolapan-Sanquicheo lineament. Post ~42 Ma deformation is essentially brittle and is characterized by several left lateral and right lateral transcurrent faults with typical Riedel patterns. Other trench-parallel left lateral shear zones active in pre-Oligocene times were recently reported in western Oaxaca. The recognizing of Early Tertiary trench-parallel and left-lateral ductile shearing in internal areas of southern Mexico suggest a field of widely

  15. High resolution aeromagnetic anomaly map of Mount Etna volcano, Southern Italy

    NASA Astrophysics Data System (ADS)

    D'Ajello Caracciolo, F.; Nicolosi, I.; Carluccio, R.; Chiappini, S.; De Ritis, R.; Giuntini, A.; Materni, V.; Messina, A.; Chiappini, M.

    2014-05-01

    A high resolution aeromagnetic survey of Mount Etna Volcano was carried out by the Airborne Geophysics Science Team of Istituto Nazionale di Geofisica e Vulcanologia (INGV), aimed at producing the most detailed magnetic anomaly map existing so far for this area. Two datasets of the total intensity of the Earth's Magnetic Field were collected at different altitudes to take into account the huge topographic variations of Etna volcano, that reaches elevations above 3300 m asl. One level was flown at the altitude of 2200 m whereas a second one over the central part, at about 3500 m of altitude. Since the region is characterized by a large presence of strongly magnetized volcanic products, the survey was carried out acquiring profile lines only, in order to optimize the resources. From the residual magnetic anomaly analysis we inferred two main trending lineaments (- 35°N and 0°N) that are related to regional tectonic stress field and we interpret the main magnetic anomaly as the effect of thickness variation of magnetized volcanic products due to the complex pre-volcanic basement morphology of Etna.

  16. Geochemistry of the Koshelev Volcano-Hydrothermal System, Southern Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Taran, Y.; Kalacheva, E.

    2015-12-01

    Koshelev is the southernmost volcano of the Kamchatkan volcanic front where magmatic plumbing systems of the Kamchatkan subduction zone cross a thick layer of the oil-gas-bearing Neogene sedimentary strata of Western Kamchatka. The volcanic massive hosts a powerful hydrothermal system, which has been drilled in early 1980s. Deep wells tapped a hot (ca. 300ºC) saline solution (up to 40 g/L of Cl), whereas the upper part of the system is a typical steam cap with temperature close to 240ºC. Two hydrothermal fields of the volcano (Upper and Lower) discharge saturated or super-heated (up to 150ºC) steam and are characterized by numerous hot pools and low flow-rate springs of steam-heated waters enriched in boron and ammonia. There is also a small lateral group of warm Na-Ca-Cl-SO4 springs (40ºC). We report here our data and review the literature geochemical data on the chemical and isotopic composition of waters and hydrothermal vapours of the Koshelev system. Data on the gas composition include He and C isotopes, as well as the chemical and isotopic composition of light hydrocarbons. Water geochemistry includes literature data on water isotopes of the deep brine and trace elements and REE of steam-heated waters. A conceptual model of the system is presented and discussed.

  17. Volcanic hotspots of the central and southern Andes as seen from space by ASTER and MODVOLC between the years 2000-2011

    NASA Astrophysics Data System (ADS)

    Jay, J.; Pritchard, M. E.; Mares, P. J.; Mnich, M. E.; Welch, M. D.; Melkonian, A. K.; Aguilera, F.; Naranjo, J.; Sunagua, M.; Clavero, J. E.

    2011-12-01

    We examine 153 volcanoes and geothermal areas in the central, southern, and austral Andes for temperature anomalies between 2000-2011 from two different spacebourne sensors: 1) those automatically detected by the MODVOLC algorithm (Wright et al., 2004) from MODIS and 2) manually identified hotspots in nighttime images from ASTER. Based on previous work, we expected to find 8 thermal anomalies (volcanoes: Ubinas, Villarrica, Copahue, Láscar, Llaima, Chaitén, Puyehue-Cordón Caulle, Chiliques). We document 31 volcanic areas with pixel integrated temperatures of 4 to more than 100 K above background in at least two images, and another 29 areas that have questionable hotspots with either smaller anomalies or a hotspot in only one image. Most of the thermal anomalies are related to known activity (lava and pyroclastic flows, growing lava domes, fumaroles, and lakes) while others are of unknown origin or reflect activity at volcanoes that were not thought to be active. A handful of volcanoes exhibit temporal variations in the magnitude and location of their temperature anomaly that can be related to both documented and undocumented pulses of activity. Our survey reveals that low amplitude volcanic hotspots detectable from space are more common than expected (based on lower resolution data) and that these features could be more widely used to monitor changes in the activity of remote volcanoes. We find that the shape, size, magnitude, and location on the volcano of the thermal anomaly vary significantly from volcano to volcano, and these variations should be considered when developing algorithms for hotspot identification and detection. We compare our thermal results to satellite InSAR measurements of volcanic deformation and find that there is no simple relationship between deformation and thermal anomalies - while 31 volcanoes have continuous hotspots, at least 17 volcanoes in the same area have exhibited deformation, and these lists do not completely overlap. In

  18. Methane Hydrate Recovered From A Mud Volcano in Santa Monica Basin, Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Normark, W. R.; Hein, J. R.; Powell, C. L.; Lorenson, T. D.; Lee, H. J.; Edwards, B. D.

    2003-12-01

    In July 2003, a short (2.1 m) piston core from the summit of a mud volcano recovered methane hydrate at a water depth of 813 m in Santa Monica Basin. The discovery core penetrated into in the hydrate as evidenced by chunks of ice and violent degassing of the core section between 162 and 212 cm depth. The core consists of shell hash and carbonate clasts (to 7-cm long) in silty mud. The methanogenic carbonates are of two types: massive, recrystallized nodular masses with an outer mm-thick sugary patina and a bivalve coquina with carbonate cement. Living clams including the genus Vesicomya, commonly found at cold-seep sites elsewhere, were recovered from the top of the core. Further sampling attempts using piston, gravity, and box corers, all of which were obtained within 15 m of the discovery core, recovered olive-brown silty mud with variable amounts of whole and fragmented bivalve shells and methanogenic carbonate fragments characteristic of cold-seep environments. Gases collected in cores adjacent to the discovery core contain elevated amounts of methane and trace amounts of heavier hydrocarbon gases, indicating some component from thermogenic sources. Hydrogen sulfide was also detected in these sediment samples. Vertical channels in one core may have served as fluid pathways. The existence of hydrate at such a shallow depth in the sediment was unexpected, however, the presence of Vesicomya and hydrogen sulfide indicate that the mud volcano is a site of active methane venting. The mud volcano, which is about 24 km west-southwest of Redondo Beach, is about 300 m in diameter at the base. No internal structure is resolved on either high resolution deep-tow boomer or single-channel air-gun profiles, most likely as a result of the gas content and sediment deformation. The diapiric structure has ascended through well-bedded sediment on the lower slope of the basin, producing as much as 30 m of bathymetric relief. It is located in an area where strike-slip motion along

  19. Tectonic Geomorphology and Volcano-Tectonic Interaction in the Eastern Boundary of the Southern Cascades (Hat Creek Graben), California, USA

    NASA Astrophysics Data System (ADS)

    Paguican, E. M. R.; Bursik, M. I.

    2015-12-01

    The eastern boundary of the Southern Cascades (Hat Creek Graben), California, USA is an extensively faulted volcanic corridor with spectacular, high, steep scarps in a bedrock of late Tertiary and Quaternary volcanic and sedimentary deposits. The morphology of the graben is a result of the plate motions associated with multiple tectonic provinces, faulting, and recurring volcanic activity from more than 500 vents, over the past 7 my. The graben is at the boundary between two distinct geologic and geomorphic areas -- the Cascade Range on the west and the Modoc Plateau on the east -- between Mt. Shasta and Medicine Lake Highlands volcano, and Lassen Volcanic Center on the north and south, respectively. This study describes the geomorphological and tectonic features, their alignment and distribution, to understand the volcano-tectonic and geomorphology relationships in the Hat Creek Graben. We interpret topographic models generated from satellite images to create a database of volcanic centers and structures, and analyze the spatial distribution of the volcanic centers in the Hat Creek Graben. Poisson Nearest Neighbor analysis reveals a clustered distribution of volcanic centers, implying continuous or recurrent activity of magma sources as it propagates to the surface. Volcanic centers in the Hat Creek Graben have multiple preferred alignments, typical for extensional tectonic environments because of competing regional and local stress field influences and the presence of pre-existing, near-surface fractures. Most small stratovolcanoes ("lava cones") on the west are influenced by normal regional stress, and have crater amphitheater openings perpendicular to the maximum horizontal stress (σHmax), while those on the east, in a transcurrent regional stress regime, are at an acute angle. These results can be used as an indicator of the degree of impingement of the Walker Lane shear zone on the Cascades region.

  20. Methanogenic calcite, 13C-depleted bivalve shells, and gas hydrate from a mud volcano offshore southern California

    USGS Publications Warehouse

    Hein, J.R.; Normark, W.R.; McIntyre, B.R.; Lorenson, T.D.; Powell, C.L., II

    2006-01-01

    Methane and hydrogen sulfide vent from a cold seep above a shallowly buried methane hydrate in a mud volcano located 24 km offshore southern California in?? 800 m of water. Bivalves, authigenic calcite, and methane hydrate were recovered in a 2.1 m piston core. Aragonite shells of two bivalve species are unusually depleted in 13C (to -91??? ??13C), the most 13C-depleted shells of marine macrofauna yet discovered. Carbon isotopes for both living and dead specimens indicate that they used, in part, carbon derived from anaerobically oxidized methane to construct their shells. The ??13C values are highly variable, but most are within the range -12??? to -91???. This variability may be diagnostic for identifying cold-seep-hydrate systems in the geologic record. Authigenic calcite is abundant in the cores down to ???1.5 m subbottom, the top of the methane hydrate. The calcite is depleted in 13C (??13C = -46??? to -58???), indicating that carbon produced by anaerobically oxidized methane is the main source of the calcite. Methane sources include a geologic hydrocarbon reservoir from Miocene source rocks, and biogenic and thermogenic degradation of organic matter in basin sediments. Oxygen isotopes indicate that most calcite formed out of isotopic equilibrium with ambient bottom water, under the influence of gas hydrate dissociation and strong methane flux. High metal content in the mud volcano sediment indicates leaching of basement rocks by fluid circulating along an underlying fault, which also allows for a high flux of fossil methane. ?? 2006 Geological Society of America.

  1. Dynamic implications of ridges on a debris avalanche deposit at Tutupaca volcano (southern Peru)

    NASA Astrophysics Data System (ADS)

    Valderrama, Patricio; Roche, Olivier; Samaniego, Pablo; van Wyk de Vries, Benjamin; Bernard, Karine; Mariño, Jersy

    2016-02-01

    Catastrophic volcanic landslides can involve different parts of a volcano that can be incorporated into any resulting debris avalanche. The different material properties may influence the mechanical behaviour and, hence, the emplacement mechanisms of the different avalanche units. We present data from a coupled hydrothermal- and magmatic-related volcanic landslide at Tutupaca volcano (Peru). Around ad 1802, the hydrothermal system under Tutupaca's growing dacite dome failed, creating a debris avalanche that triggered a large explosive eruption. A typical debris avalanche hummocky unit is found, formed out of rock from the dome foot and the underlying hydrothermally altered lavas. It is covered by a more widespread and remarkable deposit that contains remnants of the hot dome core and the inner hydrothermal material. This deposit has ridges 20-500-m long, 10-30-m wide and 1-5-m high, regularly spaced and that fan slightly outward. Cross sections exposed within the ridges reveal coarser cores and finer troughs, suggesting grain size segregation during emplacement. Ridge morphology and granulometry are consistent with fingering known to occur in granular flows. The ridges are also associated with large blocks that have evidence of differential movement compared with the rest of the flowing mass. The presence of both ridged and hummocky deposits in the same event shows that, as different lithologies combine and collapse sequentially, materials with different mechanical properties can coexist in one landslide, leading to contrasting emplacement dynamics. The different structures thus highlight the complexity of such hazardous volcanic events and show the difficulty we face with modelling them.

  2. Time-dependent vs stationary seismic hazard assessment: an application to Mt. Etna volcano (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Tuvè, T.; Azzaro, R.; D'Amico, S.; Peruzza, L.

    2009-12-01

    Hazard estimations based on the characteristic earthquake model and time-dependent renewal process are applied to the seismogenic faults at Mt. Etna volcano. Most of them are characterised by a long record of historically well-documented earthquakes occurred in the last 200 years (CMTE catalogue, Azzaro et al., 2000), often associated with coseismic surface faulting. We analyse the main seismic sequences associated to the seismotectonic domain of the Timpe system, in the eastern flank of the volcano (Azzaro, 2004). Intertimes computed for all the events which have occurred in this sector, with an epicentral intensity Io ≥ VIII EMS, show an aperiodicity coefficient (standard deviation over mean value) near to the one, typical of a stationary process; the mean recurrence time is about 17.2 years. The same analysis is also applied to a declustered catalogue, obtaining a recurrence time of 19.6 years, consistent with the value obtained by the historical rate from the catalogue. Conversely, by calculating the intertimes for each individual fault, the aperiodicity coefficient falls at ca. 0.33, depicting a quasi-periodic behaviour. For these reasons, a time-dependent approach to seismic hazard assessment by using a renewal model based on the Brownian Passage Time (BPT) distribution, is applied. Mean recurrence time of major events is calibrated by merging the inter-event times observed at each fault; aperiodicity is tuned on b-values from instrumental data, according to the approach proposed by Zoeller et al. (2008). Finally we compare these mean recurrence times with the values obtained by using only geometrical and kinematic information, as defined in Peruzza et al. (2008) for faults in Italy. Time-dependent hazard assessment is compared with the stationary assumption of seismicity, and validated in a retrospective forward model. Seismic hazard estimates is given in terms of earthquake rupture forecast: impending events are expected on the S. Tecla Fault and

  3. Geophysical surveys on permafrost in Coropuna and Chachani volcanoes (southern Peru)

    NASA Astrophysics Data System (ADS)

    Ubeda, Jose; Yoshikawa, Kenji; Pari, Walter; Palacios, David; Macias, Pablo; Apaza, Fredy; Ccallata, Beto; Miranda, Rafael; Concha, Ronald; Vasquez, Pool; Cruz, Rolando

    2015-04-01

    A network of air and ground temperature sensors installed 2004-2014 has enabled the discovery of permafrost on the Coropuna (6377 m) and Chachani (6057 m) volcanoes. However, on the Misti (5820 m) volcano there is no permafrost, which can be attributed to geothermal heat. Misti and Chachani are very close to each other, near the city of Arequipa (S. Peru). Coropuna is 150 km to the west. Various volcanic eruptions have taken place on Misti and Coropuna in the last 10 ka (Úbeda et al, 2012). The volcanic activity on the Chachani seems to be much older, although it has not been researched to date. Coropuna is covered by a glacial system of ~40 km2 (23-11-2013) and the moraines surrounding the volcanic complex indicate a surface of >500 km2 >10 ka ago (Úbeda et al, 2011). On Chachani the evidence also suggests a great extent in the past although in this case there are no glaciers conserved at the present day. On Misti there are currently no glaciers either, nor is there any evidence conserved of their earlier presence, and this has also been related to geothermal heat. As well as other study areas, the CRYOPERU sensor network includes 4 stations in the sector Coropuna-NE; 3 stations in Coropuna-SE; 3 stations in Chachani-SE and 3 stations in Misti-NW. The stations are at different altitudes, in an interval of 4300-6000 m. Each station has a thermometer to measure the air temperature (at a height of 0.50 m) and three thermometers to measure the ground temperature (at depths of 0.15, 0.30 and 1.00 m). The sensors are synchronized in GPS time and record the temperature every 30 minutes. Úbeda, J. et al (2012). Glacial and volcanic evolution on Nevado Coropuna (Tropical Andes) based on cosmogenic 36Cl surface exposure dating. EGU2012-3683-2. Úbeda, J. (2011). El impacto del cambio climático en los glaciares del complejo volcánico Nevado Coropuna (Cordillera Occidental de los Andes Centrales). PhD Thesis. Universidad Complutense de Madrid. 594 pp. http

  4. Petrology and geochemistry of high cascade volcanics in southern Washington: Mount St. Helens volcano and the Indian Heaven basalt field

    SciTech Connect

    Smith, D.R.

    1984-01-01

    Mount St. Helens volcano (Washington, USA) has been characterized by four eruptive periods during the last 2200 years. Eruptive products include a wide spectrum of rock types including basaltic to andesitic lavas, andesitic to dacitic pyroclastic flows and tephra, and dacite domes. The major and trace element compositions of some andesites and dacites are broadly consistent with their derivation from a basaltic andesite parental magma by fractional cyrstallization processes involving the observed phenocryst assemblages. However, the strontium and oxygen isotopic compositions of representative samples of the Mount St. Helens suite indicate that closed system processes cannot explain the isotopic variations. The isotopic rations are positively correlated with one another and the bulk composition (SiO/sub 2/, Mg number, etc.). The vents of the nearby Indian Heaven Quaternary volcanic field erupted several basalt types which can be defined on the basis of major and trace element composition - calcalkaline (low and high TiO/sub 2/ varieties), transitional, and tholeiitic. Several of these basalt types occur at Mount St. Helens as well, but Indian Heaven lavas are generally more primitive as indicated by higher Mg/(Mg + Fe) ratios. The distribution of volcanic rock types in relation to local structures in the Cascade Range of southern Washington and northern Oregon suggests that crustal structure may influence the degree of evolution of specific volcanic fields. Cascade arc suggests that volcanic arc magma evolution does not necessarily produce a continuous sequence from tholeiitic to calcalkaline rocks in time or space.

  5. Explosive style, magma degassing and evolution in the Chaimilla eruption, Villarrica volcano, Southern Andes

    NASA Astrophysics Data System (ADS)

    Pioli, L.; Scalisi, L.; Costantini, L.; Di Muro, A.; Bonadonna, C.; Clavero, J.

    2015-11-01

    Villarrica (Chile) is a basaltic stratovolcano, currently in an open-conduit condition. It now has relatively frequent Strombolian and effusive eruptions, but it had large explosive eruptions in prehistoric times. Among them, the most recent eruption was Chaimilla, which occurred about 3100 years ago and produced deposits that indicate complex, multiphase eruptive dynamics. Significant differences in mineralogy and glass compositions of the erupted scoria suggest the eruption was fed by two distinct magma batches with similar bulk compositions but distinct crystallization and degassing histories. The lower sequence scoria has a complex crystal assemblage with several crystal populations produced by mixing between a relatively degassed magma containing Fo75-79 olivine, normally or reversely zoned plagioclase (An70-94) and augite (type 1 magma), and a subordinate volume of more-primitive and more volatile-rich magma rising from depth (type 2 magma) and carrying normally zoned plagioclase and higher-Mg (Fo81-85) olivine crystals. Type 2 magma was the main component emitted during the larger and more explosive eruptive phase that deposited the upper sequence. The Chaimilla eruption occurred under closed-vent conditions and was fed by water-rich magmas. When compared with the petrological features of the magma currently erupted at Villarrica, which has slightly more-evolved bulk compositions, lower crystal content and lower water content, these results suggest that the evolution in eruptive style of the volcano from highly explosive to a lava lake/Strombolian activity corresponds to significant changes in the shallow plumbing system (which is now at much shallower depths); these plumbing-system changes were not associated with significant changes in the parental magma compositions.

  6. Goosenest Volcano, southern Oregon: High K[sub 2]O, BA and Sr basaltic andesite extrusives

    SciTech Connect

    Mertzman, S.A. . Dept. of Geosciences)

    1992-01-01

    Goosenest Volcano, a cinder cone with coeval lava flows, is located nearly 5 miles WNW of the south entrance into Crater Lake National Park. A summit crater unmodified by glacial erosion but with a blanket of Mazama pumice, suggests the age of latest activity to be between 20,000 and 6850 B.P. The pyroclastics and lavas from Goosenest are augite olivine basaltic andesites, with a strong tendency for these minerals to form 2--5 mm in diameter glomeroporphyritic clumps [+-] plagioclase. Three samples from the cone (2 bombs and 1 spatter agglutinate) and five from lava flows were analyzed for major and trace elements through XRF and ICP techniques. These extrusive are calc-alkaline medium to high K[sub 2]O basaltic andesites; in particular, SiO[sub 2] ranges from 53 to 54 wt. %, K[sub 2]O from 1.39 to 1.94, MgO from 6.3 to 7.3, Ba from 774 to 1,069 ppm and Sr from 1,463 to 1,951 ppm. With increasing K[sub 2]O: P[sub 2]O[sub 5], Ba, Be, Ce, La, Sr, and Zr increase in concentration while Ni, Cr, and Co decrease. All major elements are virtually constant or scatter randomly; Y,V,Sc, and Yb follow the same pattern. The lower Al[sub 2]O[sub 3] content (16 to 17 wt.%) precludes the addition of a large plagioclase component as an explanation of the high Sr content. Batch partial melting of a mineralogically homogeneous source that has been fluxed by variable amounts of an LILE-rich fluid phase whose ultimate origin is tied to the subduction process, is a likely scheme which explains the unusual chemical composition of the Gossenest extrusive rocks.

  7. Chronostratigraphy of Monte Vulture volcano (southern Italy): secondary mineral microtextures and 39Ar-40Ar systematics

    NASA Astrophysics Data System (ADS)

    Villa, Igor M.; Buettner, Annett

    2009-12-01

    The eruptive history of Monte Vulture has been the subject of several geochronological investigations during the past decades, which reliably dated only a small number of eruptions. Understanding the causes of sub-optimum data yield in the past requires an interdisciplinary approach. We re-analyzed samples from previous works and present new data on samples from the main volcano-stratigraphic units of Monte Vulture, so as to provide an improved, consistent chronostratigraphic database. Imaging of minerals by cathodoluminescence and backscattered electrons reveals that heterochemical, high-temperature deuteric reaction textures are ubiquitous. Such observations are common in metamorphic rocks but had not frequently been reported from volcanic rocks. In view of the mineralogical complexity, we base our chronological interpretation on isochemical steps, defined as steps for which the Cl/K and/or the Ca/K ratios are constant. Isochemical steps carry the isotopic signature of chemically homogeneous mineral phases and therefore allow a well-constrained age interpretation. Comparison of old and new 39Ar-40Ar data proves the reproducibility of age spectra and their shapes. This quantifies the analytical reliability of the irradiation and mass-spectrometric analyses. Anomalous age spectra are a reproducible property of some specific samples and correlate with mineralogical anomalies. The present data allow us to fine-tune the age of the volcanostratigraphic units of Monte Vulture during the known interval of main volcanic activity from ca. 740 to 610 ka. After a very long stasis, the volcanic activity in the Monte Vulture area resumed with diatremic eruptions, one of which (Lago Piccolo di Monticchio, the site of a palynological-paleoclimatological drilling) was dated at ca. 140 ka.

  8. 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

  9. Equilibrium Line Altitude fluctuations at HualcaHualca volcano (southern Peru).

    NASA Astrophysics Data System (ADS)

    Alcalá, Jesus; Palacios, David; Juan Zamorano, Jose

    2015-04-01

    Interest in Andean glaciers has substantially increased during the last decades, due to its high sensitivity to climate fluctuations. In this sense, Equilibrium Line Altitude (ELA) is a reliable indicator of climate variability that has been frequently used to reconstruct palaeoenvironmental conditions at different temporal and spatial scales. However, the number of sites with ELA reconstructions is still insufficient to determine patterns in tropical climate or estimations of atmospheric cooling since the Last Glacial Maximum. The main purpose of this study is to contribute in resolving tropical climate evolution through ELA calculations on HualcaHualca (15° 43' S; 71° 52' W; 6,025 masl), a large andesitic stratovolcano located in the south-western Peruvian Andes approximately 70 km north-west of Arequipa. We applied Terminus Headwall Altitude Ratio (THAR) with 0.2; 0.4; 0.5; 0.57 ratios, Accumulation Area Ratio (AAR) and Accumulation Area Balance Ratio (AABR) methods in four valleys of HualcaHualca volcano: Huayuray (north side), Pujro Huayjo (southwest side), Mollebaya (east side) and Mucurca (west side). To estimate ELA depression, we calculated the difference between the ELA on 1955 with its position in the Maximum Glacier Extent (MGE), Tardiglacial phases, little Ice Age (LIA) and 2000. Paleotemperature reconstructions derived from vertical temperature gradient 6.5° C / 1 km, based on GODDARD global observation system considered the most appropriate model for arid Andes. During MGE, the ELA was located between 5,005 (AABR) and 5,215 (AAR 0.67) masl. But in 1955, ELA rose to 5,685 (AABR) - 5,775 (AAR 0.67) masl. The ELA depression between those two phases is 560 - 680 m that implies a temperature decrease of 3.5° - 4.4° C. The experimental process based in the use and contrast of different ELA reconstruction techniques applied in this study suggests that THAR (0.57), AAR (0.67) or AABR are the most consistent procedures for HualcaHualca glaciers, while

  10. Nd- and Sr-isotopic compositions of lavas from the northern Mariana and southern Volcano arcs: implications for the origin of island arc melts

    NASA Astrophysics Data System (ADS)

    Lin, P. N.; Stern, R. J.; Morris, J.; Bloomer, S. H.

    1990-09-01

    Nd- and Sr-isotopic data are reported for lavas from 23 submarine and 3 subaerial volcanoes in the northern Mariana and southern Volcano arcs. Values of ɛNd range from +2.4 to +9.5 whereas 87Sr/86Sr ranges from 0.70319 to 0.70392; these vary systematically between and sometimes within arc segments. The Nd-and Sr-isotopic compositions fall in the field of ocean island basalt (OIB) and extend along the mantle array. Lavas from the Volcano arc, Mariana Central Island Province and the southern part of the Northern Seamount Province have ɛNd to +10 and 87Sr/86Sr=0.7032 to 0.7039. These are often slightly displaced toward higher 87Sr/86Sr at similar ɛNd. In contrast, those lavas from the northern part of the Mariana Northern Seamount Province as far north as Iwo Jima show OIB isotopic characteristics, with ɛNd and 87Sr/86Sr=0.7035 to 0.7039. Plots of 87Sr/86Sr and ɛNd versus Ba/La and (La/Yb)n support a model in which melts from the Mariana and Volcano arcs are derived by mixing of OIB-type mantle (or melts therefrom) and a metasomatized MORB-type mantle (or melts therefrom). An alternate interpretation is that anomalous trends on the plots of Nd- and Sr-isotopic composition versus incompatible-element ratios, found in some S-NSP lavas, suggest that the addition of a sedimentary component may be locally superimposed on the two-component mixing of mantle end-members.

  11. Petroleum degradation and associated microbial signatures at the Chapopote asphalt volcano, Southern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Schubotz, Florence; Lipp, Julius S.; Elvert, Marcus; Kasten, Sabine; Mollar, Xavier Prieto; Zabel, Matthias; Bohrmann, Gerhard; Hinrichs, Kai-Uwe

    2011-08-01

    At the Chapopote Knoll in the Southern Gulf of Mexico, deposits of asphalt provide the substrate for a prolific cold seep ecosystem extensively colonized by chemosynthetic communities. This study investigates microbial life and associated biological processes within the asphalts and surrounding oil-impregnated sediments by analysis of intact polar membrane lipids (IPLs), petroleum hydrocarbons and stable carbon isotopic compositions (δ 13C) of hydrocarbon gases. Asphalt samples are lightly to heavily biodegraded suggesting that petroleum-derived hydrocarbons serve as substrates for the chemosynthetic communities. Accordingly, detection of bacterial diester and diether phospholipids in asphalt samples containing finely dispersed gas hydrate suggests the presence of hydrocarbon-degrading bacteria. Biological methanogenesis contributes a substantial fraction to the methane captured as hydrate in the shallow asphalt deposits evidenced by significant depletion in 13C relative to background thermogenic methane. In sediments, petroleum migrating from the subsurface stimulates both methanogenesis and methanotrophy at a sulfate-methane transition zone 6-7 m below the seafloor. In this zone, microbial IPLs are dominated by archaeal phosphohydroxyarchaeols and archaeal diglycosidic diethers and tetraethers. Bacterial IPLs dominate surface sediments that are impregnated by severely biodegraded oil. In the sulfate-reduction zone, diagnostic IPLs indicate that sulfate-reducing bacteria (SRB) play an important role in petroleum degradation. A diverse mixture of phosphohydroxyarchaeols and mixed phospho- and diglycosidic archaeal tetraethers in shallow oil-impregnated sediments point to the presence of anaerobic methane-oxidizing ANME-2 and ANME-1 archaea, respectively, or methanogens. Archaeal IPLs increase in relative abundance with increasing sediment depth and decreasing sulfate concentrations, accompanied by a shift of archaeol-based to tetraether-based archaeal IPLs. The

  12. Applicability of statistical eruption analysis to the geological record of Villarrica and Lanín volcanoes, Southern Volcanic Zone, Chile

    NASA Astrophysics Data System (ADS)

    Wehrmann, Heidi; Dzierma, Yvonne

    2011-03-01

    Standard stochastic failure-analysis techniques are applied to the geological eruption records of Villarrica and Lanín volcanoes in the Chilean Southern Volcanic Zone. These statistical methods are used to estimate the probabilities of eruptions large enough to leave a trace in the geological record. For Villarrica, the standard lifetime distributions predict a near 100% probability that such an eruption should have occurred between 489 AD and today. If the VEI = 3 eruptions observed in the historical record are large enough to be preserved in the geological record, the probability of such a future eruption of Villarrica is about 20% in the next 100 years. In the case of Lanín, the applicability of the exponential, Weibull and log-logistic distributions to the geological record is doubtful, since the volcano appears to have experienced alternating high- and low-activity regimes. Only the mixture-of-exponentials distribution can take into account the possible dormancy descending to final extinction, resulting in a probability of about 16% that Lanín will ever erupt again in the future. The contrasting behaviour of the eruption records of these two neighbouring volcanoes in terms of the number of eruptions and the length of the repose-time intervals serves to examine to what extent the method can be applied to geological eruption records. This study contributes to directing statistical eruption analysis towards time scales long enough to investigate large-magnitude eruptions, and it includes the possibility of dormancy/extinction.

  13. Kinematic significance of mingling-rolling structures in lava flows: a case study from Porri Volcano (Salina, Southern Tyrrhenian Sea)

    NASA Astrophysics Data System (ADS)

    Ventura, Guido

    A basaltic andesite lava flow from Porri Volcano (Salina, Southern Tyrrhenian Sea) is composed of two different magmas. Magma A (51vol.% of crystals) has a dacitic glass composition, and magma B (18vol.% of crystals), a basaltic glass composition. Magma B is hosted in A and consists of sub-spherical enclaves and boudin-like, banding and rolling structures (RS). Four types of RS have been recognized: σ-typeδ-type complex σ-δ-types and transitional structures between sub-spherical enclaves and rolling structures. An analysis of the RS has been performed in order to reconstruct the flow kinematics and the mechanism of flow emplacement. Rolling structures have been selected in three sites located at different distances from the vent. In all sites most RS show the same sense of shear. Kinematic analysis of RS allows the degree of flow non-coaxiality to be determined. The non-coaxiality is expressed by the kinematic vorticity number Wk, a measure of the ratio Sr between pure shear strain rate and simple shear strain rate. The values of Wk calculated from the measured shapes of microscopic RS increase with increasing distance from the vent, from approximately 0.5 to 0.9. Results of the structural analysis reveal that the RS formed during the early-intermediate stage of flow emplacement. They represent originally sub-spherical enclaves deformed at low shear strain. At higher strain, RS deformed to give boudin-like and stretched banding structures. Results of the kinematic analysis suggest that high viscosity lava flows are heterogeneous non-ideal shear flows in which the degree of non-coaxiality increases with the distance from the vent. In the vent area, deformation is intermediate between simple shear and pure shear. Farther from the vent, deformation approaches ideal simple shear. Lateral extension processes occur only in the near-vent zone, where they develop in response to the lateral push of magma extruded from the vent. Lateral shortening processes develop in

  14. Carbon dioxide diffuse emission and thermal energy release from hydrothermal systems at Copahue-Caviahue Volcanic Complex (Argentina)

    NASA Astrophysics Data System (ADS)

    Chiodini, Giovanni; Cardellini, Carlo; Lamberti, María Clara; Agusto, Mariano; Caselli, Alberto; Liccioli, Caterina; Tamburello, Giancarlo; Tassi, Franco; Vaselli, Orlando; Caliro, Stefano

    2015-10-01

    The north-western sector of Caviahue caldera (Argentina), close to the active volcanic system of Copahue, is characterized by the presence of several hydrothermal sites that host numerous fumarolic emissions, anomalous soil diffuse degassing of CO2 and hot soils. In March 2014, measurements of soil CO2 fluxes in 5 of these sites (namely, Las Máquinas, Las Maquinitas I, Las Maquinitas II, Anfiteatro, and Termas de Copahue) allowed an estimation that ~ 165 t of deeply derived CO2 is daily released. The gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges. Gas equilibria within the H-C-O gas system indicate the presence of a large, probably unique, single phase vapor zone at 200-210 °C feeding the hydrothermal manifestations of Las Máquinas, Las Maquinitas I and II and Termas de Copahue. A natural thermal release of 107 MW was computed by using CO2 as a tracer of the original vapor phase. The magmatic signature of the incondensable fumarolic gases, the wide expanse of the hydrothermal areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the Caviahue caldera.

  15. Permafrost and Periglacial Activity Distribution and Geothermal Anomalies in the Chachani and El Misti Volcanoes (Southern Peru)

    NASA Astrophysics Data System (ADS)

    Palacios, D.; Andrés, N.; Úbeda, J.; Alcalá, J.

    2009-04-01

    The El Misti volcano (16˚ 17′ S, 71˚ 24′ W, 5.822 m) is considered one of the most potentially catastrophic in America. Its crater is 18 km from the centre of Arequipa (2335 m a.s.l.), a city with more than 800,000 inhabitants whose population has doubled over the last 20 years, spreading out over the volcano's sides and gullies in many new settlements, less than 12 km away from the crater. Although the last significant eruptive period occurred in 2300-2050 BP, during the last five thousand years the recurrence period for eruptions has been 500 to 1500 years (Thouret et al. 2001). The last eruption occurred between 1440 and 1447 AD, although it was low-intensity. The crater currently has fumarolic activity. The volcano does not show any signs of having supported glaciers or any periglacial form in the past. The Chachani volcanic complex (16˚ 11' S 71˚ 31' W, 6.057 m a.s.l.) lies 18 km northeast of El Misti and 22 km from the centre of the city of Arequipa. The complex is made up of several volcanic cones and domes. The date of the most recent eruption is unknown, and no current or recent eruptive activity has been recorded or detected (Paquereau et al. 2006). The complex probably supported glaciers during the Little Ice Age, although there are none at present. Geomorphological evidence shows that glaciers during the Last Glacial Maximum were very extensive, with some of their feet reaching an altitude of 4000m. Rocky glaciers up to 1800 m long can be found inside some of the cirques. The PichuPichi Complex (16° 25' 25"S 71°14'27", 5650 m a.s.l.), 22 km E of El Misti, supported substantial glaciers during the Last Glacial Maximum, with a minimum foot altitude of c.4000 m, and like the Chachani, has numerous rock glacier formations in its cirques. The aim of this paper is to ascertain whether the lack of glacial or periglacial geomorphological evidence on the El Misti volcano is due to its destruction from subsequent volcanic activity, or

  16. A remote sensing assessment of the impact of the 2010 Maule, Chile earthquake (Mw 8.8) on the volcanoes of the southern Andes

    NASA Astrophysics Data System (ADS)

    Pritchard, M. E.; Welch, M.; Jay, J.; Button, N.

    2011-12-01

    There are tantalizing, but controversial, indications that great earthquakes affect arc-wide volcanic activity. For example, analysis of historic eruptions at volcanoes of the southern Andes has shown that 3-4 eruptions were likely seismically triggered by Mw > 8 earthquakes in the Chile subduction zone -- particularly the 1906 and 1960 earthquakes (e.g., Watt et al., 2009). However, the 27 February 2010 Mw 8.8 Maule, Chile earthquake that ruptured the subduction zone between the 1960 and 1906 earthquakes does not appear to have triggered 3-4 volcanic eruptions in the same area in the 12 months after the event. In an effort to understand the relation between a large earthquake and volcanic unrest, we use a variety of satellite instruments to look for more subtle (i.e., not leading to eruption), but detectable change in thermal or deformation activity at the volcanoes of the southern Andes after the Maule earthquake and its aftershocks. For all of the volcanoes in the catalog of the Smithsonian Institution (approximately 80), we use nighttime MODIS and ASTER data to assess the thermal activity and ALOS InSAR data to characterize the surface deformation before and after the earthquake. The ALOS InSAR data are not ideal for detecting changes in deformation before and after the earthquake because of the small number of acquisitions in austral summer as well as ionospheric and tropospheric artifacts. We estimate that we could detect deformation > 5 cm/year. Similarly, the ASTER and MODIS data suffer respectively from poor temporal and spatial resolution of thermal anomalies. We update previous InSAR work that identified at least 8 areas of volcanic deformation in the southern Andes related to eruptive processes, subsidence of past lava flows, or surface uplift not associated with an eruption (Fournier et al., 2010). Of greatest interest are the two volcanic areas with the largest deformation signals between 2007-2008 (both > 15 cm/yr in the radar line of sight): Laguna

  17. Nicaraguan Volcanoes

    Atmospheric Science Data Center

    2013-04-18

    article title:  Nicaraguan Volcanoes     View Larger Image Nicaraguan volcanoes, February 26, 2000 . The true-color image at left is a ... February 26, 2000 - Plumes from the San Cristobal and Masaya volcanoes. project:  MISR category:  gallery ...

  18. Draft Genome Sequence of the Novel Thermoacidophilic Archaeon Acidianus copahuensis Strain ALE1, Isolated from the Copahue Volcanic Area in Neuquén, Argentina

    PubMed Central

    Rascovan, Nicolás; Castro, Camila; Revale, Santiago; Giaveno, M. Alejandra; Vazquez, Martín; Donati, Edgardo R.

    2014-01-01

    Acidianus copahuensis is a recently characterized thermoacidophilic archaeon isolated from the Copahue volcanic area in Argentina. Here, we present its draft genome sequence, in which we found genes involved in key metabolic pathways for developing under Copahue’s extreme environmental conditions, such as sulfur and iron oxidation, carbon fixation, and metal tolerance. PMID:24812211

  19. The 2011 Cerro Hudson volcano eruption (Southern Andes, Chile): Pre-eruptive inflation and hot spots observed with InSAR and thermal imagery

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Pritchard, M. E.; Lohman, R. B.

    2013-12-01

    Cerro Hudson is one of most active volcanoes of the Southern Andes with at least 12 documented Holocene eruptions including two large caldera forming eruptions (VEI>6) at 6700 and 3600 years BP and one of the largest eruptions of the 20th century in 1991 -- VEI of 5 and ~2.7 km3 of dense rock equivalent erupted material. The volcano had smaller eruptions in 1971 (VEI 3) and 2011 (VEI of 1-2), but despite its persistent activity, there is little monitoring because of its remote location. In this work we focus on remote sensing observations to better characterize the activity of Cerro Hudson between the 1991 and 2011 eruptions and during the 2011 eruption. Our primary technique is satellite-based interferometric synthetic aperture radar (InSAR). Although InSAR studies at Cerro Hudson are challenging given the poor data coverage as well as the presence of ice, snow and vegetation, the data show that the volcano inflated between 2004 and 2010 with a maximum range change rate between 2 and 3 cm/yr, about half of the deformation rate observed during a previously detected deformation episode from 1993-1999. Inversion for an inflating point source suggests magma accumulation beneath the SW part of the caldera at an average depth of 10 km -- deeper than the depths estimated for the magma chamber of the 1991 eruption (3 km) and a deformation event between 1993 and 1999 (5-6 km), and in a slightly different location with smaller volume changes. The center of deformation is located a few km away from the eruption location near the caldera ring fault, but the predicted static Coloumb stress changes due to the inferred inflation source would enhance motion on the caldera ring fault, suggesting that the deformation and eruptive vents may be linked. We also analize nighttime satellite thermal images from MODIS and ASTER for pixel-integrated temperatures above the background temperatures in the ice filled caldera. While MODIS did not show any unambiguous evidence for the eruption

  20. Flank instability of Stromboli volcano (Aeolian Islands, Southern Italy): Integration of GB-InSAR and geomorphological observations

    NASA Astrophysics Data System (ADS)

    Intrieri, Emanuele; Di Traglia, Federico; Del Ventisette, Chiara; Gigli, Giovanni; Mugnai, Francesco; Luzi, Guido; Casagli, Nicola

    2013-11-01

    Stromboli is characterized by frequent explosions of variable energy and periodically interrupted by more energetic blasts emitting large volumes of material. The pressurization of a volatile-poor, high-porphyritic magma column that is gas-recharged by the deep-seated, volatile-rich, low-porphyritic magma precedes such events and produces deformations on the NW flank of the volcano, Sciara del Fuoco. By integrating geomorphological observations with long-term displacements from ground-based interferometric radar since December 2007, we identified two landslides whose movements are strongly related with volcanic activity. Movement patterns obtained through a novel long-term analysis of GB-InSAR data permitted us to hypothesize the type of movement and depth for both landslides. Furthermore their position allowed us to affirm that the effusive vent formed in 2007 at 400 m a.s.l., was the result of the deflection of a feeder dike caused by landslide fractures, thus showing the important role of geomorphological discontinuities in volcanic environments.

  1. C. 1.5 Ga metamorphism of the Lazdijai 13 volcano-sedimentary sequence in southern Lithuania: its origin and implications

    NASA Astrophysics Data System (ADS)

    Siliauskas, Laurynas; Skridlaite, Grazina

    2015-04-01

    The concealed crystalline crust in the SW East European Craton consists of several domains finally accreted at 1.8-1.70 Ga (Bogdanova et al., 2014). However, some geological structures in the Lithuanian basement are still poorly reconstructed because of insufficient isotopic and geochemical data. Such is the Lazdijai 13 (Lz13) volcano-sedimentary sequence in southern Lithuania, preliminary dated at 1.83-1.80 Ga (U-Pb zircon age). The newly obtained monazite analyses (EPMA dating, Cameca SX-100 electron microprobe, Warsaw University) allowed dating of metamorphism of the Lz13 rocks. The 300 m thick Lz13 sequence is composed of deformed and metamorphosed volcanics, volcano-clastics and sediments, cross-cut by pegmatite and quartz veins. The upper part of the drilling (at c. 493 m) consists of exhalitic quartz chlorite cherts and metaandesitic rocks. They are underlain by medium-fine grained shists composed of quartz, biotite, garnet, cordierite, staurolite, minor plagioclase, K-feldspar, magnetite and monazite (felsic volcanics, 540 m) that were metamorphosed at 580° C and 6 kbar (garnet, biotite, cordierite geothermobarometry). Monazites are small, interstitial, fragmented and dissolved, some found as inclusions in magnetite. They yielded three ages: 1685±25 Ma, 1525±11Ma, and 1448±24 Ma. Another layer of a fine grained shist (quartz, biotite, garnet, K-feldspar, muscovite, 599 m) of sedimentary origin contains zircons and monazites arranged in thin, undulating lines. The monazites are small, interstitial, partly dissolved, in places overgrown by alanite aggregates. They yielded 1671±29 Ma and 1523±17 Ma ages. Below, at 757 m, a strongly deformed shist composed of quartz, biotite, K-feldspar, plagioclase, garnet and cordierite (former sediment) was metamorphosed at 498° C and 5.4 kbar (garnet, biotite, plagioclase and muscovite geothermobarometry). It contains very small, strongly dissolved and locally overgrown by alanite, monazite grains. Three of them were

  2. Geochemistry and Sr-Nd isotopic compositions of mantle xenoliths from the Monte Vulture carbonatite-melilitite volcano, central southern Italy

    NASA Astrophysics Data System (ADS)

    Downes, H.; Kostoula, T.; Jones, A. P.; Beard, A. D.; Thirlwall, M. F.; Bodinier, J.-L.

    2002-08-01

    Spinel peridotite xenoliths found in the Monte Vulture carbonatite-melilitite volcano have been derived from the subcontinental lithospheric mantle beneath central southern Italy. Clinopyroxene-poor lherzolites and harzburgites are the most common rock types, with subordinate wehrlites and dunites. Small quantities of phlogopite and carbonate are present in a few samples. The peridotites record a large degree of partial melting and have experienced subsequent enrichment which has increased their LILE and LREE contents, but in most cases their HFSE contents are low. Despite being carried to the surface by a carbonatite-melilitite host, the whole-rock and clinopyroxene compositions of the xenoliths have a trace-element signature more closely resembling that of silicate-melt metasomatised mantle rather than carbonatite-metasomatised peridotites. 87Sr/86Sr and 143Nd/144Nd isotopic ratios for clinopyroxene from the Vulture peridotites are 0.7042-0.7058 and 0.51260-0.5131 respectively. They form a trend away from the depleted mantle to the composition of the host magmas, and show a significant enrichment in 87Sr/86Sr compared with most European mantle samples. The mantle beneath Monte Vulture has had a complex evolution - we propose that the lithosphere had already undergone extensive partial melting before being affected by metasomatism from a silicate melt which may have been subduction-related.

  3. Reconstruction of glacial changes on HualcaHualca volcano (southern Peru) from the Maximum Glacier Extent to present.

    NASA Astrophysics Data System (ADS)

    Alcalá, Jesus; Palacios, David; Juan Zamorano, Jose

    2015-04-01

    Little is known about glacial area changes in the Peruvian glaciers and how responds to climate fluctuations especially in the arid region where ice masses represent the major water supply. In this research, we present the results related to glacier area, volume and minimum glacier altitude evolution from the Maximum Glacier Extent (MGE) to 2000 on HualcaHualca volcano (15° 43' S; 71° 52' W; 6,025 masl), a large andesitic stratovolcano located in the south-western Peruvian Andes approximately 70 km north-west of Arequipa. We focused the study in four valleys (Huayuray, Pujro Huayjo, Mollebaya and Mucurca) because preserved a complete and well-defined sequence of glacial deposits. Moreover, these valleys, with the exception of Mucurca, still retain ice masses relegated to active cirques on summits areas so has been possible to reconstruct glacier recent dynamics. To reconstruct former glaciers, we used frontal and lateral moraines while delimitation of recent ice masses was based on the analysis of aerial photographs (1955) as well as Landsat satellite scene (2000). Geographical Information System (GIS) allowed map and quantify with high accuracy glacier spatial parameters. The magnitude of glacial expansion was highest during MEG in Huayuray, where the glacier reached 22.7 km2 of extension and the front ice was situated at 3,650 masl, than in Pujro Huayjo (23.8 km2; 4,300 masl), Mollebaya (17.8 km2; 4,315 masl) and Mucurca (8.0 km2; 4,350 masl). The cause of this difference has been associated to the control exercised by topography. Glacier of Huayuray flowed by a steep slope while mass ices of Pujro Huayjo, Mollebaya and Mucurca slipped to the Altiplano. In the other hand, the data from 2000 show that the intensity of deglaciation was more drastic in Mucurca, where glacier has already disappeared, than in Huayuray (1.2 km2; 5,800 masl), Pujro Huayjo (1.8 km2; 5,430 masl) or Mollebaya (0.95 km2; 5,430 masl) as a consequence of it's lesser glacier entity. Research

  4. Microearthquake activity around Kueishantao island, offshore northeastern Taiwan: Insights into the volcano-tectonic interactions at the tip of the southern Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Konstantinou, K. I.; Pan, C.-Y.; Lin, C.-H.

    2013-05-01

    Kueishantao is a volcanic island located offshore the northeastern coast of Taiwan and lies at the tip of the southern Okinawa Trough which is the back-arc basin of the Ryukyu subduction zone. Its last eruption occurred during the Holocene (~ 7 ka), hence Kueishantao can be considered as an active volcano. In an effort to better understand how magmatic processes may interact with the regional tectonics, a seismic network was installed in the area during early January 2008. This network consisted of 16 three-component seismometers located both on Kueishantao and the coast of northeastern Taiwan. One year of data was analyzed yielding 425 earthquakes whose P and S arrival times were manually picked and each event was located using a nonlinear probabilistic location method. In order to improve the location accuracy, the minimum 1-D velocity model for this dataset was derived and all earthquakes were relocated using this model. The results show a tight cluster of events near Kueishantao while the remaining earthquakes are scattered between the island and mainland Taiwan. The majority of hypocentral depths range between 2.5 and 10 km where the former depth coincides with the bottom of the shallow sedimentary layer and the latter with the ductile lower crust. Waveforms of the three largest events were also inverted for the determination of their deviatoric and full moment tensor. No statistically significant isotropic component was found, while two of the events can be explained by a double-couple source. The third event exhibited a low frequency content (< 10 Hz) and a large non-double-couple component suggesting fluid involvement at its source. A stress inversion of all available focal mechanisms in the area shows that fluid circulation in the upper crust generates a local stress field around Kueishantao facilitating the opening of cracks along the NW-SE direction of regional extension.

  5. Stable sulfur and carbon isotope investigations of pore-water and solid-phase compounds in sediments of the Chapopote Asphalt Volcano, southern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Wilhelm, T.; Bruechert, V.; Pape, T.; Schubotz, F.; Kasten, S.

    2007-05-01

    During R/V Meteor cruise M67 2a/b (March-April 2006) to the Asphalt Volcanoes of the southern Gulf of Mexico two gravity cores were retrieved from the central depression of the Chapopote Knoll which contained viscous oil/asphalt a few meters below the sediment surface. Also several push cores were taken with the remotely operated vehicle (ROV) QUEST at sites where oil/asphalt reached closely below the sediment surface. From these cores solid-phase and pore-water samples were taken for on-board and subsequent shore-based analyses. Together with a core taken from a background site which is not influenced by asphalt/oil seepage these sediment and pore water samples are currently subject to detailed analyses of (1) the stable sulfur isotopic composition of both dissolved (sulfate and sulfide) and solid-phase (iron monosulfides, pyrite) sulfur compounds, and (2) the composition and stable carbon isotopic signatures of hydrocarbon gases. The major aims of these investigations are to identify whether and to which extent the upward migration of oil, asphalt and gas (1) stimulates biogeochemical processes and turn-over rates, and (2) influences the stable sulfur isotopic signatures of both dissolved and solid phase sulfur compounds. Furthermore, we seek to determine the potential of these - possibly unusual - stable sulfur isotopic signals of solid-phase sulfides to reconstruct hydrocarbon seepage in older geological records and to elucidate how the composition and the stable carbon isotopic signatures of the hydrocarbon gases are altered by the action of typical chemosynthetic communities thriving at these sites.

  6. Geochemical insight into differences in the physical structures and dynamics of two adjacent maar lakes at Mt. Vulture volcano (southern Italy)

    NASA Astrophysics Data System (ADS)

    Caracausi, A.; Nicolosi, M.; Nuccio, P. M.; Favara, R.; Paternoster, M.; Rosciglione, A.

    2013-05-01

    report on the first geochemical investigation of the Monticchio maar lakes (Mt. Vulture volcano, southern Italy) covering an annual cycle that aimed at understanding the characteristic features of the physical structures and dynamics of the two lakes. We provide the first detailed description of the lakes based on high-resolution conductivity-temperature-depth (CTD) profiles, chemical and isotopic (H and O) compositions of the water, and the amounts of dissolved gases (e.g., He, Ar, CH4, and CO2). The combined data set reveals that the two lakes, which are separated by less than 200 m, exhibit different dynamics: one is a meromictic lake, where the waters are rich in biogenic and mantle-derived gases, while the other is a monomictic lake, which exhibits complete turnover of the water in winter and the release of dissolved gases. Our data strongly suggest that the differences in the dynamics of the two lakes are due to different density profiles affected by dissolved solutes, mainly Fe, which is strongly enriched in the deep water of the meromictic lake. A conceptual model of water balance was constructed based on the correlation between the chemical composition of the water and the hydrogen isotopic signature. Gas-rich groundwaters that feed both of the lakes and evaporation processes subsequently modify the water chemistry of the lakes. Our data highlight that no further potential hazardous accumulation of lethal gases is expected at the Monticchio lakes. Nevertheless, geochemical monitoring is needed to prevent the possibility of vigorous gas releases that have previously occurred in historical time.

  7. Chikurachki Volcano

    Atmospheric Science Data Center

    2013-04-16

    ... plume from the April 22, 2003, eruption of the Chikurachki volcano is portrayed in these views from the Multi-angle Imaging ... the volcanically active Kuril Island group, the Chikurachki volcano is an active stratovolcano on Russia's Paramushir Island (just south of ...

  8. Tales of volcanoes and El-Niño southern oscillations with the oxygen isotope anomaly of sulfate aerosol

    PubMed Central

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L.; McCabe, Justin; Savarino, Joel; Thiemens, Mark H.

    2013-01-01

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth’s system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980–2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher ∆17O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and ∆17O = 3.3‰, OEI = 11 and ∆17O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that ∆17O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  9. Tales of volcanoes and El-Nino southern oscillations with the oxygen isotope anomaly of sulfate aerosol.

    PubMed

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L; McCabe, Justin; Savarino, Joel; Thiemens, Mark H

    2013-10-29

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher (17)O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and (17)O = 3.3‰, OEI = 11 and (17)O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that (17)O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  10. Dante's volcano

    NASA Astrophysics Data System (ADS)

    1994-09-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  11. Dante's Volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  12. Intimate association of sI and sII hydrate structures at the Chapopote asphalt volcano, southern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Klapp, S. A.; Murshed, M. M.; Pape, T.; Klein, H.; Bohrmann, G.; Kuhs, W. F.; Brewer, P. G.

    2009-12-01

    Intimate associations of two gas hydrate structures seem to be uncommon in most known hydrate deposits. Here we report on a mixture of hydrate structure I (sI) and structure II (sII) from the Chapopote asphalt volcano in the southern Gulf of Mexico. Gas hydrates were found within the matrix and pores of asphalts extruded at the seafloor. Three gas hydrate pieces were studied in high spatial resolution using high-energy synchrotron X-rays to investigate the crystal structure and the crystallite size distributions (CSD), by gas chromatography and by Raman spectroscopy. Hydrate-bound gases of all three hydrate pieces were composed mostly of methane (94 - 98 mol% of C1—C5 hydrocarbons). Two of the hydrate pieces comprised only sI gas hydrate, formed predominantly from methane. The other piece comprised an intimate mixture of both sI and sII, with sII representing ca. 25 wt.% and sI ca. 75 wt.% of the present hydrate phase. The crystallites of sII had an arithmetical mean size of about 380 µm. The mean crystallite sizes of sI clustered at about 200 µm. The CSD of sII hydrate was shaped in a normal distribution, slightly skewed toward larger sizes. Instead, 2 from a total of 3 sI CSDs were skewed to small sizes. Raman spectroscopy revealed that sI and sII were closely associated within individual grains/agglomerates on a scale of tens to hundreds µm. The differences in crystallite sizes of sI and sII are significant, suggesting differences in the nucleation density or different ages of the crystallites, if time is the dominant factor in the crystallite size evolution. The coexistence of the two structures may be a result of one or of a combination of several independent processes: i) de-mixing into two hydrate structures from the gas phase, which provides an additional degree of freedom for lowering the free energy in the system; ii) fractionated crystallization with a changing gas composition during crystallization; and iii) simultaneous crystallization of

  13. Time spans of soil formation and late Pleistocene-Holocene climate changes in the Somma-Vesuvius volcano area, southern Italy

    NASA Astrophysics Data System (ADS)

    Scarciglia, Fabio; Zumpano, Veronica; Sulpizio, Roberto; Terribile, Fabio; Pulice, Iolanda; La Russa, Mauro F.

    2013-04-01

    Time spans of soil formation and climate changes occurred during the late Pleistocene to the middle Holocene are investigated in a pedostratigraphic succession located in the piedmont of the Somma-Vesuvius volcano (Campania region, southern Italy) using a multidisciplinary approach. We focused on five well-known and well-dated primary tephra and four interlayered volcanic soils developed on and/or buried by them. The pyroclastic layers give detailed chronological constraints to the stratigraphy. From bottom to top the following tephra were identified in the field: Pomici di Base (22 ka BP), Pomici Verdoline (19 ka BP), Agnano Pomici Principali (12.26 ka BP), Mercato (8.9 ka BP) and Avellino (3.9 ka BP), all of them representing volcanic products of explosive eruptions of the Somma-Vesuvius, except the third one, sourced from the westerly Phlegrean Fields. The four pedons were characterized in terms of morphological, physical, chemical, mineralogical and micromorphological features. Special attention was given to reconstruct the main soil-forming processes, paleoenvironmental and paleoclimatic conditions, degree of soil development and associated time ranges. Moreover, further tephra were identified in the field within some of above pedons. One of them was easily recognized and referred to the Agnano Monte Spina eruption (4.2-4.3 ka BP, Phlegrean Fields provenance), whereas the others were not previously known in the Somma-Vesuvius stratigraphy. On the basis of SEM-EDS analyses (chemical composition and morphoscopic observations), coupled with their stratigraphic position and literature compositional databases, they were related to the Soccavo 4-5 and the Tufi Biancastri eruptions from the Phlegrean Fields. This interpretation permitted to fix further age constrains for more detailed assessment of rates of soil formation and climatic interpretation. Major late Quaternary climatic phases are suggested by changes in the extent of development of andic properties, iron

  14. Contrasting records from mantle to surface of Holocene lavas of two nearby arc volcanic complexes: Caburgua-Huelemolle Small Eruptive Centers and Villarrica Volcano, Southern Chile

    NASA Astrophysics Data System (ADS)

    Morgado, E.; Parada, M. A.; Contreras, C.; Castruccio, A.; Gutiérrez, F.; McGee, L. E.

    2015-11-01

    Most of the small eruptive centers of the Andean Southern Volcanic Zone are built over the Liquiñe-Ofqui Fault Zone (LOFZ), a NS strike-slip (> 1000 km length) major structure, and close to large stratovolcanoes. This contribution compares textural features, compositional parameters, and pre- and syn-eruptive P,T conditions, between basaltic lavas of the Caburgua-Huelemolle Small Eruptive Centers (CHSEC) and the 1971 basaltic andesite lava of the Villarrica Volcano located 10 km south of the CHSEC. Olivines and clinopyroxenes occur as phenocrysts and forming crystal clots of the studied lavas. They do not markedly show compositional differences, except for the more scattered composition of the CHSEC clinopyroxenes. Plagioclase in CHSEC lavas mainly occur as phenocrysts or as microlites in a glass-free matrix. Two groups of plagioclase phenocrysts were identified in the 1971 Villarrica lava based on crystal size, disequilibrium features and zonation patterns. Most of the CHSEC samples exhibit higher LaN/YbN and more scattered Sr-Nd values than 1971 Villarrica lava samples, which are clustered at higher 143Nd/144Nd values. Pre-eruptive temperatures of the CHSEC-type reservoir between 1162 and 1165 ± 6 °C and pressures between 10.8 and 11.4 ± 1.7 kb consistent with a deep-seated reservoir were obtained from olivine-augite phenocrysts. Conversely, olivine-augite phenocrysts of 1971 Villarrica lava samples record pre-eruptive conditions of two stages or pauses in the magma ascent to the surface: 1208 ± 6 °C and 6.3-8.1 kb ± 1.7 kb (deep-seated reservoir) and 1164-1175 ± 6 °C and ≤ 1.4 kb (shallow reservoir). At shallow reservoir conditions a magma heating prior to the 1971 Villarrica eruption is recorded in plagioclase phenocrysts. Syn-eruptive temperatures of 1081-1133 ± 6 °C and 1123-1148 ± 6 °C were obtained in CHSEC and 1971 Villarrica lava, respectively using equilibrium olivine-augite microlite pairs. The LOFZ could facilitate a direct transport to

  15. Unzipping of the volcano arc, Japan

    NASA Astrophysics Data System (ADS)

    Stern, R. J.; Smoot, N. C.; Rubin, M.

    1984-02-01

    A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin.

  16. Unzipping of the volcano arc, Japan

    USGS Publications Warehouse

    Stern, R.J.; Smoot, N.C.; Rubin, M.

    1984-01-01

    A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: 1. (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. 2. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. 3. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin. ?? 1984.

  17. Spreading Volcanoes

    NASA Astrophysics Data System (ADS)

    Borgia, Andrea; Delaney, Paul T.; Denlinger, Roger P.

    As volcanoes grow, they become ever heavier. Unlike mountains exhumed by erosion of rocks that generally were lithified at depth, volcanoes typically are built of poorly consolidated rocks that may be further weakened by hydrothermal alteration. The substrates upon which volcanoes rest, moreover, are often sediments lithified by no more than the weight of the volcanic overburden. It is not surprising, therefore, that volcanic deformation includes-and in the long term is often dominated by-spreading motions that translate subsidence near volcanic summits to outward horizontal displacements around the flanks and peripheries. We review examples of volcanic spreading and go on to derive approximate expressions for the time volcanoes require to deform by spreading on weak substrates. We also demonstrate that shear stresses that drive low-angle thrust faulting from beneath volcanic constructs have maxima at volcanic peripheries, just where such faults are seen to emerge. Finally, we establish a theoretical basis for experimentally derived scalings that delineate volcanoes that spread from those that do not.

  18. Spreading volcanoes

    USGS Publications Warehouse

    Borgia, A.; Delaney, P.T.; Denlinger, R.P.

    2000-01-01

    As volcanoes grow, they become ever heavier. Unlike mountains exhumed by erosion of rocks that generally were lithified at depth, volcanoes typically are built of poorly consolidated rocks that may be further weakened by hydrothermal alteration. The substrates upon which volcanoes rest, moreover, are often sediments lithified by no more than the weight of the volcanic overburden. It is not surprising, therefore, that volcanic deformation includes-and in the long term is often dominated by-spreading motions that translate subsidence near volcanic summits to outward horizontal displacements around the flanks and peripheries. We review examples of volcanic spreading and go on to derive approximate expressions for the time volcanoes require to deform by spreading on weak substrates. We also demonstrate that shear stresses that drive low-angle thrust faulting from beneath volcanic constructs have maxima at volcanic peripheries, just where such faults are seen to emerge. Finally, we establish a theoretical basis for experimentally derived scalings that delineate volcanoes that spread from those that do not.

  19. Chilean Volcanoes

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On the border between Chile and the Catamarca province of Argentina lies a vast field of currently dormant volcanoes. Over time, these volcanoes have laid down a crust of magma roughly 2 miles (3.5 km) thick. It is tinged with a patina of various colors that can indicate both the age and mineral content of the original lava flows. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on May 15, 1999. This is a false-color composite image made using shortwave infrared, infrared, and green wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  20. Mahukona: The missing Hawaiian volcano

    SciTech Connect

    Garcia, M.O.; Muenow, D.W. ); Kurz, M.D. )

    1990-11-01

    New bathymetric and geochemical data indicate that a seamount west of the island of Hawaii, Mahukona, is a Hawaiian shield volcano. Mahukona has weakly alkalic lavas that are geochemically distinct. They have high {sup 3}He/{sup 4}He ratios (12-21 times atmosphere), and high H{sub 2}O and Cl contents, which are indicative of the early state of development of Hawaiian volcanoes. The He and Sr isotopic values for Mahukona lavas are intermediate between those for lavas from Loihi and Manuna Loa volcanoes and may be indicative of a temporal evolution of Hawaiian magmas. Mahukona volcano became extinct at about 500 ka, perhaps before reaching sea level. It fills the previously assumed gap in the parallel chains of volcanoes forming the southern segment of the Hawaiian hotspot chain. The paired sequence of volcanoes was probably caused by the bifurcation of the Hawaiian mantle plume during its ascent, creating two primary areas of melting 30 to 40 km apart that have persisted for at least the past 4 m.y.

  1. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

    ... of which are so thick that they block the penetration of light from CALIPSO's lidar to the surface. The yellow layer near the surface over France is believed to be primarily air pollution, but could also contain ash from the volcano. Highlighting its ...

  2. Shoshonite and sub-alkaline magmas from an ultrapotassic volcano: Sr-Nd-Pb isotope data on the Roccamonfina volcanic rocks, Roman Magmatic Province, Southern Italy

    NASA Astrophysics Data System (ADS)

    Conticelli, Sandro; Marchionni, Sara; Rosa, Davide; Giordano, Guido; Boari, Elena; Avanzinelli, Riccardo

    2009-01-01

    The Roccamonfina volcano is characterised by two stages of volcanic activity that are separated by volcano-tectonic caldera collapses. Ultrapotassic leucite-bearing rocks are confined to the pre-caldera stage and display geochemical characteristics similar to those of other volcanoes in the Roman Province. After the major sector collapse of the volcano, occurred at ca. 400 ka, shoshonitic rocks erupted from cinder cones and domes both within the caldera and on the external flanks of the pre-caldera Roccamonfina volcano. On the basis of new trace element and Sr-Nd-Pb isotope data, we show that the Roccamonfina shoshonitic rocks are distinct from shoshonites of the Northern Roman Province, but are very similar to those of the Neapolitan volcanoes. The last phases of volcanic activity erupted sub-alkaline magmas as enclaves in trachytic domes, and as lavas within the Monte Santa Croce dome. Ultrapotassic rocks of the pre-caldera composite volcano are plagioclase-bearing leucitites characterised by high levels of incompatible trace elements with an orogenic signature having troughs at Ba, Ta, Nb, and Ti, and peaks at Cs, K, Th, U, and Pb. Initial values of 87Sr/86Sr range from 0.70926 to 0.70999, 143Nd/144Nd ranges from 0.51213 to 0.51217, while the lead isotope rations vary between 18.788-18.851 for 206Pb/204Pb, 15.685-15.701 for 207Pb/204Pb, and 39.048-39.076 for 208Pb/204Pb. Shoshonites show a similar pattern of trace element depletions and enrichments to the earlier ultrapotassic leucite-bearing rocks but have a larger degree of differentiation and lower concentrations of incompatible trace elements. On the other hand, shoshonitic rocks have Sr, Nd, and Pb isotopes consistently different than pre-caldera ultrapotassic leucite-bearing rocks. 87Sr/86Sr ranges from 0.70665 to 0.70745, 143Nd/144Nd ranges from 0.51234 to 0.51238, 206Pb/204Pb ranges from 18.924 to 19.153, 207Pb/204Pb ranges from 15.661 to 15.694, and 208Pb/204Pb ranges from 39.084 to 39.212. High-K calc

  3. Santorini Volcano

    USGS Publications Warehouse

    Druitt, T.H.; Edwards, L.; Mellors, R.M.; Pyle, D.M.; Sparks, R.S.J.; Lanphere, M.; Davies, M.; Barreirio, B.

    1999-01-01

    Santorini is one of the most spectacular caldera volcanoes in the world. It has been the focus of significant scientific and scholastic interest because of the great Bronze Age explosive eruption that buried the Minoan town of Akrotiri. Santorini is still active. It has been dormant since 1950, but there have been several substantial historic eruptions. Because of this potential risk to life, both for the indigenous population and for the large number of tourists who visit it, Santorini has been designated one of five European Laboratory Volcanoes by the European Commission. Santorini has long fascinated geologists, with some important early work on volcanoes being conducted there. Since 1980, research groups at Cambridge University, and later at the University of Bristol and Blaise Pascal University in Clermont-Ferrand, have collected a large amount of data on the stratigraphy, geochemistry, geochronology and petrology of the volcanics. The volcanic field has been remapped at a scale of 1:10 000. A remarkable picture of cyclic volcanic activity and magmatic evolution has emerged from this work. Much of this work has remained unpublished until now. This Memoir synthesizes for the first time all the data from the Cambridge/Bristol/Clermont groups, and integrates published data from other research groups. It provides the latest interpretation of the tectonic and magmatic evolution of Santorini. It is accompanied by the new 1:10 000 full-colour geological map of the island.

  4. Geodynamic interpretations of plate subduction in the northernmost part of the Central Volcanic Zone from the geochemical evolution and quantification of the crustal contamination of the Nevado Solimana volcano, southern Peru

    NASA Astrophysics Data System (ADS)

    Vatin-Pérignon, Nicole; Oliver, Richard A.; Goemans, Pierre; Keller, Francine; Briqueu, Louis; Guido Salas, A.

    1992-04-01

    The northernmost volcanoes of the Central Volcanic Zone (CVZ, southern Peru) form three isolated composite centres along the western side of the active arc segment. This particular situation is comparable to the Chilean volcanic region at the southernmost end of the CVZ; in both cases, volcanoes lie close to the discontinuity where the Benioff zone becomes less steeply inclined and where crustal thickness decreases. The Solimana volcano (15°25'S), the oldest of the northerly eruptive centres, is built upon a Late Precambrian/Palaeozoic basement intruded by an Upper Cretaceous granite and unconformably overlain by Cenozoic volcanics. After a mid-Miocene andesitic activity along N10° regional faults, the Solimana volcanic history ranged from 4 Ma to Recent and built a composite andesite/dacite centre which consists of two units, preand post-caldera collapses and a youngest intra-caldera basaltic andesite phreatomagmatic activity. Fumaroles with thermal hot springs and precipitates indicate continuing activity of this volcano. North of 16°S, other adjacent volcanoes show the same evolution. Mineral chemistry and geochemical variations of the Solimana series are similar to those obtained from most high-K CVZ lavas and are largely consistent with fractionation processes. A restricted range of compositions of phenocryst assemblages, together with trace element data showing prominent LIL element enrichments relative to HFS element depletions, are typical of subduction-related continental arc magmas. However, this localized volcanism in the vicinity of the Nazca ridge-continent collision shows specific signatures: a weakly positive correlation between 87Sr/ 86Sr and Rb/Sr ratios, a high Ba and Sr content of basaltic andesites and both low ɛ Nd (- 2 to - 4) and high ɛSr (+16 to +21) values show differences north of 16°S from those to the south and suggest that distinct processes have controlled this environment. High Ba values for the most primitive lavas may be

  5. Nyiragonga Volcano

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image of the Nyiragonga volcano eruption in the Congo was acquired on January 28, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters about 50 to 300 feet ), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    Image: A river of molten rock poured from the Nyiragongo volcano in the Congo on January 18, 2002, a day after it erupted, killing dozens, swallowing buildings and forcing hundreds of thousands to flee the town of Goma. The flow continued into Lake Kivu. The lave flows are depicted in red on the image indicating they are still hot. Two of them flowed south form the volcano's summit and went through the town of Goma. Another flow can be seen at the top of the image, flowing towards the northwest. One of Africa's most notable volcanoes, Nyiragongo contained an active lava lake in its deep summit crater that drained catastrophically through its outer flanks in 1977. Extremely fluid, fast-moving lava flows draining from the summit lava lake in 1977 killed 50 to 100 people, and several villages were destroyed. The image covers an area of 21 x 24 km and combines a thermal band in red, and two infrared bands in green and blue.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the

  6. Mount Rainier, a decade volcano

    SciTech Connect

    Kuehn, S.C.; Hooper, P.R. . Dept. of Geology); Eggers, A.E. . Dept. of Geology)

    1993-04-01

    Mount Rainier, recently designated as a decade volcano, is a 14,410 foot landmark which towers over the heavily populated southern Puget Sound Lowland of Washington State. It last erupted in the mid-1800's and is an obvious threat to this area, yet Rainier has received little detailed study. Previous work has divided Rainier into two distinct pre-glacial eruptive episodes and one post-glacial eruptive episode. In a pilot project, the authors analyzed 253 well-located samples from the volcano for 27 major and trace elements. Their objective is to test the value of chemical compositions as a tool in mapping the stratigraphy and understanding the eruptive history of the volcano which they regard as prerequisite to determining the petrogenesis and potential hazard of the volcano. The preliminary data demonstrates that variation between flows is significantly greater than intra-flow variation -- a necessary condition for stratigraphic use. Numerous flows or groups of flows can be distinguished chemically. It is also apparent from the small variation in Zr abundances and considerable variation in such ratios as Ba/Nb that fractional crystallization plays a subordinate role to some form of mixing process in the origin of the Mount Rainier lavas.

  7. Inverse steptoes in Las Bombas volcano, as an evidence of explosive volcanism in a solidified lava flow field. Southern Mendoza-Argentina

    NASA Astrophysics Data System (ADS)

    Risso, Corina; Prezzi, Claudia; Orgeira, María Julia; Nullo, Francisco; Margonari, Liliana; Németh, Karoly

    2015-11-01

    Here we describe the unusual genesis of steptoes in Las Bombas volcano- Llancanelo Volcanic Field (LVF) (Pliocene - Quaternary), Mendoza, Argentina. Typically, a steptoe forms when a lava flow envelops a hill, creating a well-defined stratigraphic relationship between the older hill and the younger lava flow. In the Llancanelo Volcanic Field, we find steptoes formed with an apparent normal stratigraphic relationship but an inverse age-relationship. Eroded remnants of scoria cones occur in "circular depressions" in the lava field. To express the inverse age-relationship between flow fields and depression-filled cones here we define this landforms as inverse steptoes. Magnetometric analysis supports this inverse age relationship, indicating reverse dipolar magnetic anomalies in the lava field and normal dipolar magnetization in the scoria cones (e.g. La Bombas). Negative Bouguer anomalies calculated for Las Bombas further support the interpretation that the scoria cones formed by secondary fracturing on already solidified basaltic lava flows. Advanced erosion and mass movements in the inner edge of the depressions created a perfectly excavated circular depression enhancing the "crater-like" architecture of the preserved landforms. Given the unusual genesis of the steptoes in LVF, we prefer the term inverse steptoe for these landforms. The term steptoe is a geomorphological name that has genetic implications, indicating an older hill and a younger lava flow. Here the relationship is reversed.

  8. Real-time measurements of Hg0 and H2S at La Solfatara Crater (Campi Flegrei, Southern Italy) and Mt. Amiata volcano (Siena, Central Italy): a new geochemical approach to estimate the distribution of air contaminants

    NASA Astrophysics Data System (ADS)

    Cabassi, J.; Calabrese, S.; Tassi, F.; Venturi, S.; Capecchiacci, F.; Di Lonardo, C.; D'Alessandro, W.; Vaselli, O.

    2014-12-01

    The emission of Hg and H2S from natural and anthropogenic sources may have a great environmental impact in urban areas as well as in the surroundings of active and passive degassing volcanoes. Mercury is present in the atmosphere mainly in its elemental form (Hg0~98 %), which has a relatively high volatility, low solubility and chemical inertness. Hydrogen sulfide, one of the most abundant gas species in volcanic fluids, is highly poisoning and corrosive. In this study, an innovative real-time method for the measurements of Hg0 and H2S concentrations in air was carried out at La Solfatara Crater, a hydrothermally altered tuff-cone nested in the town of Pozzuoli (Southern Italy), and at Mt. Amiata volcano (Central Italy), where a world-class Hg mining district abandoned in the seventies and a presently-exploited geothermal field for the production of electrical energy occur. The main aims were (i) to test this new methodological approach and (ii) to investigate Hg0 and H2S concentrations and the chemical-physical parameters regulating their spatial distribution in polluted areas. A portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M) was used in combination with a pulsed fluorescence gas analyzer (Thermo Scientific Model 450i) to measure Hg0 and H2S, respectively. The instruments were synchronized and set at high-frequency acquisition (10 sec and 1 min, respectively). Measurements were carried out along pathways (up to 12 km long) at an average speed of <10 km/h and coupled with GPS data and meteorological parameters. In selected sites, passive samplers were positioned to determine the time-integrated Hg0 and H2S concentrations to be compared with the real-time measurements. The results indicate that this approach is highly efficient and effective in providing reliable and reproducible Hg0 and H2S concentrations and can be used to identify and characterize gas emitters in different environments.

  9. A Scientific Excursion: Volcanoes.

    ERIC Educational Resources Information Center

    Olds, Henry, Jr.

    1983-01-01

    Reviews an educationally valuable and reasonably well-designed simulation of volcanic activity in an imaginary land. VOLCANOES creates an excellent context for learning information about volcanoes and for developing skills and practicing methods needed to study behavior of volcanoes. (Author/JN)

  10. Focus: alien volcanos

    NASA Astrophysics Data System (ADS)

    Carroll, Michael; Lopes, Rosaly

    2007-03-01

    Part 1: Volcanoes on Earth - blowing their top; Part 2: Volcanoes of the inner Solar System - dead or alive: the Moon, Mercury, Mars, Venus; Part 3: Volcanoes of the outer Solar System - fire and ice: Io, Europa, Ganymede and Miranda, Titan, Triton, Enceladus.

  11. Structural and geochemical constraints on the reassembly of disrupted mid-Miocene volcanoes in the Lake Mead-Eldorado Valley area of southern Nevada

    NASA Astrophysics Data System (ADS)

    Weber, Michael E.; Smith, Eugene I.

    1987-06-01

    In the Lake Mead-Eldorado Valley (LMEV) area of southern Nevada, mid-Tertiary volcanic and plutonic rocks in the River, McCullough, and Eldorado mountains lie in the upper plate of a regional detachment structure. The detachment structure and strike-slip faults of the Lake Mead fault zone are temporally and kinematically related. Strike-slip systems and normal faults (Eldorado Valley fault) serve as boundaries between regions of variable extension in the upper plate of this detachment. Geochemical correlation and geometric reconstructions suggest that prior to extension, the LMEV area was characterized by three stratovolcano complexes, each above or adjacent to a chemically correlative pluton. Geochemical correlation techniques are useful tools that may have general application in reconstructing structurally disrupted volcanic-plutonic terranes. *Present address: Department of Geology, University of North Carolina, Chapel Hill, North Carolina 27514

  12. Volcano seismology

    USGS Publications Warehouse

    Chouet, B.

    2003-01-01

    A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with wide dynamic range, and development of new powerful analysis techniques, rapid progress is being made toward a synthesis of high-quality seismic data to develop a coherent model of eruption mechanics. Examples of recent advances are: (1) high-resolution tomography to image subsurface volcanic structures at scales of a few hundred meters; (2) use of small-aperture seismic antennas to map the spatio-temporal properties of long-period (LP) seismicity; (3) moment tensor inversions of very-long-period (VLP) data to derive the source geometry and mass-transport budget of magmatic fluids; (4) spectral analyses of LP events to determine the acoustic properties of magmatic and associated hydrothermal fluids; and (5) experimental modeling of the source dynamics of volcanic tremor. These promising advances provide new insights into the mechanical properties of volcanic fluids and subvolcanic mass-transport dynamics. As new seismic methods refine our understanding of seismic sources, and geochemical methods better constrain mass balance and magma behavior, we face new challenges in elucidating the physico-chemical processes that cause volcanic unrest and its seismic and gas-discharge manifestations. Much work remains to be done toward a synthesis of seismological, geochemical, and petrological observations into an integrated model of volcanic behavior. Future important goals must include: (1) interpreting the key types of magma movement, degassing and boiling events that produce characteristic seismic phenomena; (2) characterizing multiphase fluids in subvolcanic

  13. Alaska Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Murray, Tom; Read, Cyrus

    2008-01-01

    Steam plume from the 2006 eruption of Augustine volcano in Cook Inlet, Alaska. Explosive ash-producing eruptions from Alaska's 40+ historically active volcanoes pose hazards to aviation, including commercial aircraft flying the busy North Pacific routes between North America and Asia. The Alaska Volcano Observatory (AVO) monitors these volcanoes to provide forecasts of eruptive activity. AVO is a joint program of the U.S. Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Augustine volcano and AVO at http://www.avo.alaska.edu.

  14. Volcanoes: Nature's Caldrons Challenge Geochemists.

    ERIC Educational Resources Information Center

    Zurer, Pamela S.

    1984-01-01

    Reviews various topics and research studies on the geology of volcanoes. Areas examined include volcanoes and weather, plate margins, origins of magma, magma evolution, United States Geological Survey (USGS) volcano hazards program, USGS volcano observatories, volcanic gases, potassium-argon dating activities, and volcano monitoring strategies.…

  15. Galactic Super Volcano Similar to Iceland Volcano

    NASA Video Gallery

    This composite image from NASAs Chandra X-ray Observatory with radio data from the Very Large Array shows a cosmic volcano being driven by a black hole in the center of the M87 galaxy. This eruptio...

  16. Mud volcanoes of trinidad as astrobiological analogs for martian environments.

    PubMed

    Hosein, Riad; Haque, Shirin; Beckles, Denise M

    2014-01-01

    Eleven onshore mud volcanoes in the southern region of Trinidad have been studied as analog habitats for possible microbial life on Mars. The profiles of the 11 mud volcanoes are presented in terms of their physical, chemical, mineralogical, and soil properties. The mud volcanoes sampled all emitted methane gas consistently at 3% volume. The average pH for the mud volcanic soil was 7.98. The average Cation Exchange Capacity (CEC) was found to be 2.16 kg/mol, and the average Percentage Water Content was 34.5%. Samples from three of the volcanoes, (i) Digity; (ii) Piparo and (iii) Devil's Woodyard were used to culture bacterial colonies under anaerobic conditions indicating possible presence of methanogenic microorganisms. The Trinidad mud volcanoes can serve as analogs for the Martian environment due to similar geological features found extensively on Mars in Acidalia Planitia and the Arabia Terra region. PMID:25370529

  17. Mud Volcanoes of Trinidad as Astrobiological Analogs for Martian Environments

    PubMed Central

    Hosein, Riad; Haque, Shirin; Beckles, Denise M.

    2014-01-01

    Eleven onshore mud volcanoes in the southern region of Trinidad have been studied as analog habitats for possible microbial life on Mars. The profiles of the 11 mud volcanoes are presented in terms of their physical, chemical, mineralogical, and soil properties. The mud volcanoes sampled all emitted methane gas consistently at 3% volume. The average pH for the mud volcanic soil was 7.98. The average Cation Exchange Capacity (CEC) was found to be 2.16 kg/mol, and the average Percentage Water Content was 34.5%. Samples from three of the volcanoes, (i) Digity; (ii) Piparo and (iii) Devil’s Woodyard were used to culture bacterial colonies under anaerobic conditions indicating possible presence of methanogenic microorganisms. The Trinidad mud volcanoes can serve as analogs for the Martian environment due to similar geological features found extensively on Mars in Acidalia Planitia and the Arabia Terra region. PMID:25370529

  18. The Volcano Adventure Guide

    NASA Astrophysics Data System (ADS)

    Goff, Fraser

    2005-05-01

    Adventure travels to volcanoes offer chance encounters with danger, excitement, and romance, plus opportunities to experience scientific enlightenment and culture. To witness a violently erupting volcano and its resulting impacts on landscape, climate, and humanity is a powerful personal encounter with gigantic planetary forces. To study volcano processes and products during eruptions is to walk in the footsteps of Pliny himself. To tour the splendors and horrors of 25 preeminent volcanoes might be the experience of a lifetime, for scientists and nonscientists alike. In The Volcano Adventure Guide, we now have the ultimate tourist volume to lead us safely to many of the world's famous volcanoes and to ensure that we will see the important sites at each one.

  19. Chemical characteristics of magma and related seafloor sulfide deposits on back-arc spreading center and off-ridge volcanoes in Southern Mariana Trough

    NASA Astrophysics Data System (ADS)

    Urabe, T.; Kanamori, S.; Ishibashi, J.; Kentaro, K.; Sato, H.; Kato, S.; Toyoda, S.

    2012-12-01

    The back-arc basalt in Mariana Trough is characterized by fluid-dominated components (Stolper and Newman, 1994). They suggested that the H2O-enriched magma of the Mariana Trough is formed as melting mixture between MORB-type mantle source and H2O-rich component which is likely to be derived from the subducting slab. Four active and one inactive hydrothermal sites were found within a distance of 5 km in Southern Mariana Trough; that is, Snail site (12o57.19'N, 143o37.16'E, depth:2861m) and Yamanaka site (12o56.64'N, 143o36.80'E, depth: 2823m) on the spreading-axis, Archean site (12o56.35'N, 143o37.89'E, depth: 2986m), and Pika+Urashima sites (12o55.13'N, 143o38.92'E, depth: 2773m) on the off-axis seamount, respectively. We conducted nine BMS (Benthic Multi-coring System) drillings during the Hakurei-Maru No.2 cruise of TAIGA project (see below) in June 2010. Both basalt glasses and associated seafloor massive sulfide ores from these sites are cored and served for ICP-MS analyses. Multi-element plot of basalt glass indicates that both on-axis and off-axis basalts have similar pattern and are categorized as differentiated MORB and basaltic andesite which cannot be produced by fractionation of MORB, respectively. Sulfide ores at on-axis and off-axis sites show similar mineral assemblage of pyrite/marcasite, sphalerite, chalcopyrite, barite, and limited occurrence of galena only at on-axis site. Fluid-mobile elements such as As, Ba, Pb and others in sulfide ores show systematic increase at off-axis sites which reflect the influence of subduction zone fluids towards the Mariana arc. The sulfur isotope composition of pyrite/marcasite from on-axis sites shows values (+6.4 - +7.9 permil) typically observed in arc magma-related hydrothermal deposits (Suzuki, unpubl. data). On the other hand, those observed at off-axis sites (Archean; +3.6 - +6.9 permil, Pika; +0.8 - +3.5 permil) are similar to the composition of sulfides on mid-ocean ridges where the influence of sulfur

  20. Geochemistry, geochronology, and Sr-Nd isotopes of the Late Neoproterozoic Wadi Kid volcano-sedimentary rocks, Southern Sinai, Egypt: Implications for tectonic setting and crustal evolution

    NASA Astrophysics Data System (ADS)

    Moghazi, Abdel-Kader M.; Ali, Kamal A.; Wilde, Simon A.; Zhou, Qin; Andersen, Tom; Andresen, Arild; Abu El-Enen, Mahrous M.; Stern, Robert J.

    2012-12-01

    The Kid Group is one of the few exposures of Neoproterozoic metavolcano-sedimentary rocks in the basement of southern Sinai in the northernmost Arabian-Nubian Shield. It is divided into the mostly metamorphosed volcaniclastic Melhaq and siliciclastic Um Zariq formations in the north and the mostly volcanic Heib and Tarr formations in the south. The Heib, Tarr, and Melhaq formations reflect an intense episode of igneous activity and immature clastic deposition associated with core-complex formation during Ediacaran time, but Um Zariq metasediments are relicts of an older (Cryogenian) sedimentary sequence. The latter yielded detrital zircons with concordant ages as young as 647 ± 12 Ma, which may indicate that the protolith of Um Zariq schist was deposited after ~ 647 Ma but 19 concordant zircons gave a 206Pb/238U weighted mean age of 813 ± 6 Ma, which may represent the maximum depositional age of this unit. In contrast, a cluster of 11 concordant detrital zircons from the Melhaq Formation yield a weighted mean 206Pb/238U age of 615 ± 6 Ma. Zircons from Heib Formation rhyolite clast define a 206Pb/238U weighted mean age of 609 ± 5 Ma, which is taken to approximate the age of Heib and Tarr formation volcanism. Intrusive syenogranite sample from Wadi Kid yields a 206Pb/238U weighted mean age of 604 ± 5 Ma. These constraints indicate that shallow-dipping mylonites formed between 615 ± 6 Ma and 604 ± 5 Ma. Geochemical data for volcanic samples from the Melhaq and Heib formations and the granites show continuous major and trace element variations corresponding to those expected from fractional crystallization. The rocks are enriched in large ion lithophile and light rare earth elements, with negative Nb anomalies. These reflect magmas generated by melting of subduction-modified lithospheric mantle, an inference that is further supported by ɛNd(t) = + 2.1 to + 5.5. This mantle source obtained its trace element characteristics by interaction with fluids and melts

  1. Native sulfur, sulfates and sulfides from the active Campi Flegrei volcano (southern Italy): Genetic environments and degassing dynamics revealed by mineralogy and isotope geochemistry

    NASA Astrophysics Data System (ADS)

    Piochi, Monica; Mormone, Angela; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe

    2015-10-01

    We investigated sulfur-bearing minerals from the Campi Flegrei caldera, southern Italy, in relation to the increase of hydrothermal activity phenomena since 2006, aimed at providing insights into the volcanic system dynamics. Mineral encrustations and muds were sampled between 2013 and 2015 at the long-standing degassing crater of the Solfatara tuff cone and its recently restless north-eastern Pisciarelli slope. Deep-seated sulfides were further separated from two drill cores (AGIP's Mofete boreholes: 1500 m and 2695 m depth). The mineral assemblage and texture of sampled encrustations were determined by X-ray diffraction, optical and scanning electron microscopy and X-ray microanalysis by energy dispersive spectrometry. Native sulfur and alunite dominate among the newly formed mineral phases. Other minerals are mostly alunogen, and locally pickeringite, potassium alum, hematite and pyrite. Mereiterite and amarillite sporadically occur. The mud pools are rich in gypsum, potassium alum and pyrite. Quartz and argillic phases, locally with analcime, are dispersed in the outcropping rocks. δ34S values were determined for shallow subsurface native sulfur (- 5.5 to 0.0‰) and alunite (- 1.7 to - 0.2‰), as well as for the deep-seated pyrite (3.3 to 7.4‰ in the depth range:1500-2695 m). δ18O values were measured for shallow native alunite (4.2 to 7.0‰). Pisciarelli alunite was finally analyzed for its 87Sr/86Sr ratio and 143Nd/144Nd ratios (0.707517 ± 6 and 0.512459 ± 6, respectively). Textural and isotopic data constrain the genesis of alunite at the expense of K-feldspars through rock alteration by hydrothermal fluids. We suggest that the caldera is a low-sulfidation system hosting acid-sulfate deposits in its active degassing area. The acid-sulfate environment developed on an argillitic facies that thins outwards and is characteristic for steam-heated and magmatic-steam environments. These environments developed in relation to the fractured settings that

  2. Yellowstone Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Lowenstern, Jacob

    2008-01-01

    Eruption of Yellowstone's Old Faithful Geyser. Yellowstone hosts the world's largest and most diverse collection of natural thermal features, which are the surface expression of magmatic heat at shallow depths in the crust. The Yellowstone system is monitored by the Yellowstone Volcano Observatory (YVO), a partnership among the U.S. Geological Survey (USGS), Yellowstone National Park, and the University of Utah. YVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Yellowstone and YVO at http://volcanoes.usgs.gov/yvo.

  3. Mud volcanoes on Mars?

    NASA Technical Reports Server (NTRS)

    Komar, Paul D.

    1991-01-01

    The term mud volcano is applied to a variety of landforms having in common a formation by extrusion of mud from beneath the ground. Although mud is the principal solid material that issues from a mud volcano, there are many examples where clasts up to boulder size are found, sometimes thrown high into the air during an eruption. Other characteristics of mud volcanoes (on Earth) are discussed. The possible presence of mud volcanoes, which are common and widespread on Earth, on Mars is considered.

  4. Volcanoes and volcanic provinces - Martian western hemisphere

    NASA Technical Reports Server (NTRS)

    Scott, D. H.

    1982-01-01

    The recognition of some Martian landforms as volcanoes is based on their morphology and geologic setting. Other structures, however, may exhibit classic identifying features to a varying or a less degree; these may be only considered provisionally as having a volcanic origin. Regional geologic mapping of the western hemisphere of Mars from Viking images has revealed many more probable volcanoes and volcanotectonic features than were recognized on Mariner 9 pictures. These abundant volcanoes have been assigned to several distinct provinces on the basis of their areal distribution. Although the Olympus-Tharsis region remains as the principle center of volcanism on Mars, four other important provinces are now also recognized: the lowland plains, Tempe Terra plateau, southern highlands (in the Phaethontis and Thaumasia quadrangles), and a probable ignimbrite province, situated along the highland-lowland boundary in Amazonis Planitia. Volcanoes in any one province vary in morphlogy, size, and age, but volcanoes in each province tend to have common characteristics that distinguish that particular group.

  5. Geochemical and B-Sr-Nd isotopic evidence for mingling and mixing processes in the magmatic system that fed the Astroni volcano (4.1-3.8 ka) within the Campi Flegrei caldera (southern Italy)

    NASA Astrophysics Data System (ADS)

    Tonarini, Sonia; D'Antonio, Massimo; Di Vito, Mauro Antonio; Orsi, Giovanni; Carandente, Antonio

    2009-02-01

    The Astroni volcano was built through seven eruptions that generated pyroclastic deposits and lava domes within the Campi Flegrei caldera (southern Italy) 4.1-3.8 ka BP. Whole-rock geochemical and B-Sr-Nd isotopic investigations were carried out on representative samples of all seven eruptions. The products vary from tephriphonolites to phonolites, and from latites to trachytes. They show textural, mineralogical and isotopic evidence of disequilibrium, including distinct clinopyroxene populations, rounded and/or resorbed plagioclase and alkali-feldspar, and reverse-zoned phenocrysts of all these mineral phases. The Sr, Nd and B isotopic composition of whole rocks is variable and correlated with the degree of chemical evolution, suggesting open-system processes in addition to fractional crystallisation. Moreover, significant Sr-isotopic disequilibrium between the phenocrysts and glass has been documented for one sample. The chemostratigraphy of the products indicates that Astroni eruptions 1 through 5 were fed by magmas of trachytic to phonolitic composition that were less enriched in radiogenic Sr and 11B up-section. This variability has been interpreted as the result of mingling between at least two distinct magmatic end-members, one more evolved and the other less evolved. Another heterogeneous batch of magma, resulting from almost complete mixing between the same two end-members, was drained during eruptions 6 and 7. The more evolved end-member, characterised by 87Sr/ 86Sr ≥ 0.7075, 143Nd/ 144Nd ≤ 0.51247 and δ11B ≥ - 8‰, was very similar to the magma that fed the final phases of the Agnano-Monte Spina eruption, which occurred a few centuries earlier in the Astroni vent area. The less evolved end-member had 87Sr/ 86Sr ≤ 0.70726, 143Nd/ 144Nd ≥ 0.51251 and δ11B ≤ 10‰, and was likely derived by fractional crystallisation of a mantle-derived magma. An abrupt decrease in both the Sr isotope ratio and the Th content, detected at the transition

  6. Reunion Island Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On January 16, 2002, lava that had begun flowing on January 5 from the Piton de la Fournaise volcano on the French island of Reunion abruptly decreased, marking the end of the volcano's most recent eruption. These false color MODIS images of Reunion, located off the southeastern coast of Madagascar in the Indian Ocean, were captured on the last day of the eruption (top) and two days later (bottom). The volcano itself is located on the southeast side of the island and is dark brown compared to the surrounding green vegetation. Beneath clouds (light blue) and smoke, MODIS detected the hot lava pouring down the volcano's flanks into the Indian Ocean. The heat, detected by MODIS at 2.1 um, has been colored red in the January 16 image, and is absent from the lower image, taken two days later on January 18, suggesting the lava had cooled considerably even in that short time. Earthquake activity on the northeast flank continued even after the eruption had stopped, but by January 21 had dropped to a sufficiently low enough level that the 24-hour surveillance by the local observatory was suspended. Reunion is essentially all volcano, with the northwest portion of the island built on the remains of an extinct volcano, and the southeast half built on the basaltic shield of 8,630-foot Piton de la Fournaise. A basaltic shield volcano is one with a broad, gentle slope built by the eruption of fluid basalt lava. Basalt lava flows easily across the ground remaining hot and fluid for long distances, and so they often result in enormous, low-angle cones. The Piton de la Fournaise is one of Earth's most active volcanoes, erupting over 150 times in the last few hundred years, and it has been the subject of NASA research because of its likeness to the volcanoes of Mars. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  7. Physical volcanology of the submarine Mariana and Volcano Arcs

    NASA Astrophysics Data System (ADS)

    Bloomer, Sherman H.; Stern, Robert J.; Smoot, N. Christian

    1989-05-01

    Narrow-beam maps, selected dredge samplings, and surveys of the Mariana and Volcano Arcs identify 42 submarine volcanos. Observed activity and sample characteristics indicate 22 of these to be active or dormant. Edifices in the Volcano Arc are larger than most of the Mariana Arc edifices, more irregularly shaped with numerous subsidiary cones, and regularly spaced at 50 70 km. Volcanos in the Mariana Arc tend to be simple cones. Sets of individual cones and volcanic ridges are elongate parallel to the trend of the arc or at 110° counterclockwise from that trend, suggesting a strong fault control on the distribution of arc magmas. Volcanos in the Mariana Arc are generally developed west of the frontal arc ridge, on rifted frontal arc crust or new back-arc basin crust. Volcanos in the central Mariana Arc are usually subaerial, large (> 500 km3), and spaced about 50 70 km apart. Those in the northern and southern Marianas are largely submarine, closer together, and generally less than 500 km3 in volume. There is a shoaling of the arc basement around Iwo Jima, accompanied by the appearance of incompatible-element enriched lavas with alkalic affinities. The larger volcanic edifices must reflect either a higher magma supply rate or a greater age for the larger volcanos. If the magma supply (estimated at 10 20 km3/km of arc per million years at 18° N) has been relatively constant along the Mariana Arc, we can infer a possible evolutionary sequence for arc volcanos from small, irregularly spaced edifices to large (over 1000 km3) edifices spaced at 50 70 km. The volcano distribution and basal depths are consistent with the hypothesis of back-arc propagation into the Volcano Arc.

  8. Shaking up volcanoes

    USGS Publications Warehouse

    Prejean, Stephanie G.; Haney, Matthew M.

    2014-01-01

    Most volcanic eruptions that occur shortly after a large distant earthquake do so by random chance. A few compelling cases for earthquake-triggered eruptions exist, particularly within 200 km of the earthquake, but this phenomenon is rare in part because volcanoes must be poised to erupt in order to be triggered by an earthquake (1). Large earthquakes often perturb volcanoes in more subtle ways by triggering small earthquakes and changes in spring discharge and groundwater levels (1, 2). On page 80 of this issue, Brenguier et al. (3) provide fresh insight into the interaction of large earthquakes and volcanoes by documenting a temporary change in seismic velocity beneath volcanoes in Honshu, Japan, after the devastating Tohoku-Oki earthquake in 2011.

  9. Seismic Structure Beneath Taal Volcano, Philippines

    NASA Astrophysics Data System (ADS)

    You, S. H.; Gung, Y.; Konstantinou, K. I.; Lin, C. H.

    2014-12-01

    The very active Taal Volcano is situated 60 km south of Metro Manila in the southern part of Luzon Island. Based on its frequent explosive eruptions and high potential hazards to nearby population of several million, Taal Volcano is chosen as one of the 15 most dangerous "Decade Volcanoes" in the world. We deployed a temporary seismic network consisting of 8 stations since March 2008. The temporal network was operated from late March 2008 to mid March 2010 and recorded over 2270 local earthquakes. In the early data processing stages, unexpected linear drifting of clock time was clearly identified from ambient noise cross-correlation functions for a number of stations. The drifting rates of all problematic stations were determined as references to correct timing errors prior to further processing. Initial locations of earthquakes were determined from manually picking P- and S-phases arrivals with a general velocity model based on AK135. We used travel times of 305 well-located local events to derive a minimum 1-D model using VELEST. Two major earthquake groups were noticed from refined locations. One was underneath the western shore of Taal Lake with a linear feature, and the other spread at shallower depths showing a less compact feature around the eastern flank of Taal Volcano Island. We performed seismic tomography to image the 3D structure beneath Taal Volcano using a well-established algorithm, LOTOS. Some interesting features are noted in the tomographic results, such as a probable solidified past magma conduit below the northwestern corner of Taal Volcano Island, characterized by high Vp, Vs, and low Vp/Vs ratio, and a potential large hydrothermal reservoir beneath the central of Taal Volcano Island, characterized by low Vs and high Vp/Vs ratio. Combining the results of seismicity and tomographic images, we also suggest the potential existence of a magma chamber beneath the southwestern Taal Lake, and a magma conduit or fault extending from there to the

  10. Small Volcano in Terra Cimmeria

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 26 June 2002) The Science This positive relief feature (see MOLA context) in the ancient highlands of Mars appears to be a heavily eroded volcanic center. The top of this feature appears to be under attack by the erosive forces of the martian wind. Light-toned streaks are visible, trending northeast to southwest, and may be caused by scouring of the terrain, or they may be dune forms moving sand. The northeast portion of the caldera area looks as though a layer of material is being removed to expose a slightly lighter-toned surface underneath. The flanks of this feature are slightly less cratered than the surrounding terrain, which could be explained in two ways: 1) this feature may be younger than the surrounding area, and has had less time to accumulate meteorite impacts, or 2) the slopes that are observed today may be so heavily eroded that the original, cratered surfaces are now gone, exposing relatively uncratered rocks. Although most of Terra Cimmeria has low albedo, some eastern portions, such as shown in this image, demonstrate an overall lack of contrast that attests to the presence of a layer of dust mantling the surface. This dust, in part, is responsible for the muted appearance and infill of many of the craters at the northern and southern ends of this image The Story This flat-topped volcano pops out from the surface, the swirls of its ancient lava flows running down onto the ancient highlands of Mars. Its smooth top appears to be under attack by the erosive forces of the martian wind. How can you tell? Click on the image above for a close-up look. You'll see some light-toned streaks that run in a northeast-southwest direction. They are caused either by the scouring of the terrain or dunes of moving sand. Either way, the wind likely plays upon the volcano's surface. Look also for the subtle, nearly crescent shaped feature at the northeast portion of the volcano's cap. It looks as if a layer of material has been removed by the wind, exposing

  11. Volcano seismicity in Alaska

    NASA Astrophysics Data System (ADS)

    Buurman, Helena

    I examine the many facets of volcano seismicity in Alaska: from the short-lived eruption seismicity that is limited to only the few weeks during which a volcano is active, to the seismicity that occurs in the months following an eruption, and finally to the long-term volcano seismicity that occurs in the years in which volcanoes are dormant. I use the rich seismic dataset that was recorded during the 2009 eruption of Redoubt Volcano to examine eruptive volcano seismicity. I show that the progression of magma through the conduit system at Redoubt could be readily tracked by the seismicity. Many of my interpretations benefited greatly from the numerous other datasets collected during the eruption. Rarely was there volcanic activity that did not manifest itself in some way seismically, however, resulting in a remarkably complete chronology within the seismic record of the 2009 eruption. I also use the Redoubt seismic dataset to study post-eruptive seismicity. During the year following the eruption there were a number of unexplained bursts of shallow seismicity that did not culminate in eruptive activity despite closely mirroring seismic signals that had preceded explosions less than a year prior. I show that these episodes of shallow seismicity were in fact related to volcanic processes much deeper in the volcanic edifice by demonstrating that earthquakes that were related to magmatic activity during the eruption were also present during the renewed shallow unrest. These results show that magmatic processes can continue for many months after eruptions end, suggesting that volcanoes can stay active for much longer than previously thought. In the final chapter I characterize volcanic earthquakes on a much broader scale by analyzing a decade of continuous seismic data across 46 volcanoes in the Aleutian arc to search for regional-scale trends in volcano seismicity. I find that volcanic earthquakes below 20 km depth are much more common in the central region of the arc

  12. Volcanoes: Coming Up from Under.

    ERIC Educational Resources Information Center

    Science and Children, 1980

    1980-01-01

    Provides specific information about the eruption of Mt. St. Helens in March 1980. Also discusses how volcanoes are formed and how they are monitored. Words associated with volcanoes are listed and defined. (CS)

  13. Earthquake sources near Uturuncu Volcano

    NASA Astrophysics Data System (ADS)

    Keyson, L.; West, M. E.

    2013-12-01

    Uturuncu, located in southern Bolivia near the Chile and Argentina border, is a dacitic volcano that was last active 270 ka. It is a part of the Altiplano-Puna Volcanic Complex, which spans 50,000 km2 and is comprised of a series of ignimbrite flare-ups since ~23 ma. Two sets of evidence suggest that the region is underlain by a significant magma body. First, seismic velocities show a low velocity layer consistent with a magmatic sill below depths of 15-20 km. This inference is corroborated by high electrical conductivity between 10km and 30km. This magma body, the so called Altiplano-Puna Magma Body (APMB) is the likely source of volcanic activity in the region. InSAR studies show that during the 1990s, the volcano experienced an average uplift of about 1 to 2 cm per year. The deformation is consistent with an expanding source at depth. Though the Uturuncu region exhibits high rates of crustal seismicity, any connection between the inflation and the seismicity is unclear. We investigate the root causes of these earthquakes using a temporary network of 33 seismic stations - part of the PLUTONS project. Our primary approach is based on hypocenter locations and magnitudes paired with correlation-based relative relocation techniques. We find a strong tendency toward earthquake swarms that cluster in space and time. These swarms often last a few days and consist of numerous earthquakes with similar source mechanisms. Most seismicity occurs in the top 10 kilometers of the crust and is characterized by well-defined phase arrivals and significant high frequency content. The frequency-magnitude relationship of this seismicity demonstrates b-values consistent with tectonic sources. There is a strong clustering of earthquakes around the Uturuncu edifice. Earthquakes elsewhere in the region align in bands striking northwest-southeast consistent with regional stresses.

  14. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Expedition Five crew members aboard the International Space Station (ISS) captured this overhead look at the smoke and ash regurgitated from the erupting volcano Mt. Etna on the island of Sicily, Italy in October 2002. Triggered by a series of earthquakes on October 27, 2002, this eruption was one of Etna's most vigorous in years. This image shows the ash plume curving out toward the horizon. The lighter-colored plumes down slope and north of the summit seen in this frame are produced by forest fires set by flowing lava. At an elevation of 10,990 feet (3,350 m), the summit of the Mt. Etna volcano, one of the most active and most studied volcanoes in the world, has been active for a half-million years and has erupted hundreds of times in recorded history.

  15. Volcano Near Pavonis Mons

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-549, 19 November 2003

    The volcanic plains to the east, southeast, and south of the giant Tharsis volcano, Pavonis Mons, are dotted by dozens of small volcanoes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 2.1oS, 109.1oW. The elongate depression in the lower left (southwest) quarter of the image is the collapsed vent area for this small, unnamed volcano. A slightly sinuous, leveed channel runs from the depression toward the upper right (north-northeast); this is the trace of a collapsed lava tube. The entire scene has been mantled by dust, such that none of the original volcanic rocks are exposed--except minor occurrences on the steepest slopes in the vent area. The scene is 3 km (1.9 mi) wide and illuminated by sunlight from the left/upper left.

  16. Volcano-electromagnetic effects

    USGS Publications Warehouse

    Johnston, Malcolm J. S.

    2007-01-01

    Volcano-electromagnetic effects—electromagnetic (EM) signals generated by volcanic activity—derive from a variety of physical processes. These include piezomagnetic effects, electrokinetic effects, fluid vaporization, thermal demagnetization/remagnetization, resistivity changes, thermochemical effects, magnetohydrodynamic effects, and blast-excited traveling ionospheric disturbances (TIDs). Identification of different physical processes and their interdependence is often possible with multiparameter monitoring, now common on volcanoes, since many of these processes occur with different timescales and some are simultaneously identified in other geophysical data (deformation, seismic, gas, ionospheric disturbances, etc.). EM monitoring plays an important part in understanding these processes.

  17. A preliminary seismic study of Taal Volcano, Luzon Island Philippines

    NASA Astrophysics Data System (ADS)

    You, S.-H.; Gung, Y.; Lin, C.-H.; Konstantinou, K. I.; Chang, T.-M.; Chang, E. T. Y.; Solidum, R.

    2013-03-01

    The very active Taal Volcano lies in the southern part of Luzon Island only 60 km from Manila, the capital of the Philippines. In March 2008 we deployed a temporary seismic network around Taal that consisted of 8 three-component short period seismometers. This network recorded during the period from March to November 2008 about 1050 local events. In the early data processing stages, unexpected linear drifting of clock time was clearly identified for a number of stations. The drifting rates of each problematic station were determined and the errors were corrected before further processing. Initial location of each event was derived by manually picked P-/S-phases arrival times using HYPO71 and a general velocity model based on AK135. Since the velocity structure beneath Taal is essentially unknown, we used travel times of 338 well-located events in order to derive a minimum 1D velocity model using VELEST. The resulting locations show that most events occurred at the shallow depth beneath the Taal Volcano, and two major earthquake groups were noticed, with one lying underneath the western shore of Taal lake and the other one spread around the eastern flank of the Taal Volcano. Since there is no reported volcano activities during the operation period of our seismic array, we are still not confident to interpret these findings in terms of other natures of volcano at the current stage. However, our work represents an important pioneer step towards other more advanced seismic studies in Taal Volcano.

  18. Petrologic diversity of Hrafnfjordur central volcano, northwest Iceland: Iceland's oldest central volcano

    NASA Astrophysics Data System (ADS)

    Jordan, B. T.

    2012-12-01

    Hrafnfjordur central volcano in northwest Iceland is exposed along the southern and western fjords of the Jokulfirdir, encompassing an area of ~400 km2. Field studies in 2004 and 2011 under the auspices of the Keck Geology Consortium investigated the southern and western portions of the Hrafnfjordur central volcano, mapping and sampling approximately 75% of the system. Hrafnfjordur central volcano has not been dated, but a basalt underlying tuff correlated to central volcano deposits yielded a whole-rock Ar/Ar plateau age of 14.20 +/- 0.33 (2σ) Ma (Jordan & Duncan, unpub. data). The dated lava is ~550 m below the tuff, and applying an accumulation rate of 1,600 m/m.y. (Kristjansson & Jonsson, 2007) produces an estimated age of ~13.9 Ma. This would make Hrafnfjordur the oldest central volcano exposed in Iceland. Mapping and sampling to this point have documented abundant andesite and dacite lavas, and several sequences of basalts and basaltic andesites. A notable feature of Hrafnfjordur central volcano is the absence of true rhyolites in the area mapped so far. A suite of dacites exposed in the fjord Hrafnfjordur exhibits a tight linear trend of decreasing Zr (1010-460 ppm) with increasing SiO2 (65.3-69.9 wt.%), indicating progressive zircon-involved fractionation. Elevated Zr/Nb of the parental dacite, relative to local basalts, precludes an origin by fractional crystallization from a basaltic parent, and thus its origin is interpreted to be crustal melting. A dacite exposed at Leirufjordur falls on the same trend and may correlate with those at Hrafnfjordur. Another trend of dacites and andesites sampled in both fjords is characterized by low Zr (160-200 ppm). This trend could represent magma mixing between basalt and a hypothetical highly evolved low-Zr high-silica rhyolite that either is not exposed or was never erupted. Most of the andesites and basaltic andesites plot on inflected trends consistent with an origin primarily by fractional crystallization from a

  19. Mud Volcanoes as Exploration Targets on Mars

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy Z.

    2010-01-01

    Tens of thousands of high-albedo mounds occur across the southern part of the Acidalia impact basin on Mars. These structures have geologic, physical, mineralogic, and morphologic characteristics consistent with an origin from a sedimentary process similar to terrestrial mud volcanism. The potential for mud volcanism in the Northern Plains of Mars has been recognized for some time, with candidate mud volcanoes reported from Utopia, Isidis, northern Borealis, Scandia, and the Chryse-Acidalia region. We have proposed that the profusion of mounds in Acidalia is a consequence of this basin's unique geologic setting as the depocenter for the tune fraction of sediments delivered by the outflow channels from the highlands.

  20. Of Rings and Volcanoes

    NASA Astrophysics Data System (ADS)

    2002-01-01

    Office National d'Etudes et de Recherches Aérospatiales (ONERA) , Laboratoire d'Astrophysique de Grenoble (LAOG) and the DESPA and DASGAL laboratories of the Observatoire de Paris in France, in collaboration with ESO. The CONICA infra-red camera was built, under an ESO contract, by the Max-Planck-Institut für Astronomie (MPIA) (Heidelberg) and the Max-Planck Institut für Extraterrestrische Physik (MPE) (Garching) in Germany, in collaboration with ESO. Saturn - Lord of the rings ESO PR Photo 04a/02 ESO PR Photo 04a/02 [Preview - JPEG: 460 x 400 pix - 54k] [Normal - JPEG: 1034 x 800 pix - 200k] Caption : PR Photo 04a/02 shows the giant planet Saturn, as observed with the VLT NAOS-CONICA Adaptive Optics instrument on December 8, 2001; the distance was 1209 million km. It is a composite of exposures in two near-infrared wavebands (H and K) and displays well the intricate, banded structure of the planetary atmosphere and the rings. Note also the dark spot at the south pole at the bottom of the image. One of the moons, Tethys, is visible as a small point of light below the planet. It was used to guide the telescope and to perform the adaptive optics "refocussing" for this observation. More details in the text. Technical information about this photo is available below. This NAOS/CONICA image of Saturn ( PR Photo 04a/02 ), the second-largest planet in the solar system, was obtained at a time when Saturn was close to summer solstice in the southern hemisphere. At this moment, the tilt of the rings was about as large as it can be, allowing the best possible view of the planet's South Pole. That area was on Saturn's night side in 1982 and could therefore not be photographed during the Voyager encounter. The dark spot close to the South Pole is a remarkable structure that measures approximately 300 km across. It was only recently observed in visible light from the ground with a telescope at the Pic du Midi Observatory in the Pyrenees (France) - this is the first infrared image to

  1. Volcanoes and the Environment

    NASA Astrophysics Data System (ADS)

    Marti, Edited By Joan; Ernst, Gerald G. J.

    2005-10-01

    Volcanoes and the Environment is a comprehensive and accessible text incorporating contributions from some of the world's authorities in volcanology. This book is an indispensable guide for those interested in how volcanism affects our planet's environment. It spans a wide variety of topics from geology to climatology and ecology; it also considers the economic and social impacts of volcanic activity on humans. Topics covered include how volcanoes shape the environment, their effect on the geological cycle, atmosphere and climate, impacts on health of living on active volcanoes, volcanism and early life, effects of eruptions on plant and animal life, large eruptions and mass extinctions, and the impact of volcanic disasters on the economy. This book is intended for students and researchers interested in environmental change from the fields of earth and environmental science, geography, ecology and social science. It will also interest policy makers and professionals working on natural hazards. An all-inclusive text that goes beyond the geological working of volcanoes to consider their environmental and sociological impacts Each chapter is written by one of the world's leading authorities on the subject Accessible to students and researchers from a wide variety of backgrounds

  2. Santa Maria Volcano, Guatemala

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The eruption of Santa Maria volcano in 1902 was one of the largest eruptions of the 20th century, forming a large crater on the mountain's southwest flank. Since 1922, a lava-dome complex, Santiaguito, has been forming in the 1902 crater. Growth of the dome has produced pyroclastic flows as recently as the 2001-they can be identified in this image. The city of Quezaltenango (approximately 90,000 people in 1989) sits below the 3772 m summit. The volcano is considered dangerous because of the possibility of a dome collapse such as one that occurred in 1929, which killed about 5000 people. A second hazard results from the flow of volcanic debris into rivers south of Santiaguito, which can lead to catastrophic flooding and mud flows. More information on this volcano can be found at web sites maintained by the Smithsonian Institution, Volcano World, and Michigan Tech University. ISS004-ESC-7999 was taken 17 February 2002 from the International Space Station using a digital camera. The image is provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Searching and viewing of additional images taken by astronauts and cosmonauts is available at the NASA-JSC Gateway to

  3. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, R.I.

    1980-01-01

    One of the most spectacular, awesomely beautiful, and at times, most destructive displays of natural energy is an erupting volcano, belching fume and ash thousands of feet into the atmoshpehere and pouring out red-hot molten lava in fountains and streams. 

  4. The Volcano Adventure Guide

    NASA Astrophysics Data System (ADS)

    Lopes, Rosaly

    2005-02-01

    This guide contains vital information for anyone wishing to visit, explore, and photograph active volcanoes safely and enjoyably. Following an introduction that discusses eruption styles of different types of volcanoes and how to prepare for an exploratory trip that avoids volcanic dangers, the book presents guidelines to visiting 42 different volcanoes around the world. It is filled with practical information that includes tour itineraries, maps, transportation details, and warnings of possible non-volcanic dangers. Three appendices direct the reader to a wealth of further volcano resources in a volume that will fascinate amateur enthusiasts and professional volcanologists alike. Rosaly Lopes is a planetary geology and volcanology specialist at the NASA Jet Propulsion Laboratory in California. In addition to her curatorial and research work, she has lectured extensively in England and Brazil and written numerous popular science articles. She received a Latinas in Science Award from the Comision Feminil Mexicana Nacional in 1991 and since 1992, has been a co-organizer of the United Nations/European Space Agency/The Planetary Society yearly conferences on Basic Science for the Benefit of Developing Countries.

  5. Geology of Kilauea volcano

    SciTech Connect

    Moore, R.B. . Federal Center); Trusdell, F.A. . Hawaiian Volcano Observatory)

    1993-08-01

    This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower east rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailed geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. 71 refs., 2 figs.

  6. Nyamuragira Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  7. Nyamuragira Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  8. Catalogue of Icelandic Volcanoes

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Gudmundsson, Magnus T.; Vogfjord, Kristin; Pagneux, Emmanuel; Oddsson, Bjorn; Barsotti, Sara; Karlsdottir, Sigrun

    2016-04-01

    The Catalogue of Icelandic Volcanoes is a newly developed open-access web resource in English intended to serve as an official source of information about active volcanoes in Iceland and their characteristics. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the effort of FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite. Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene (the time since the end of the last glaciation - approximately the last 11,500 years). In the last 50 years, over 20 eruptions have occurred in Iceland displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and the distribution lava and tephra. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in numerous scientific papers and other publications. In 2010, the International Civil Aviation Organisation (ICAO) funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU through the FP7 project FUTUREVOLC. The Catalogue of Icelandic Volcanoes is a collaboration of the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Civil Protection Department of the National Commissioner of the Iceland Police, with contributions from a large number of specialists in Iceland and elsewhere. The Catalogue is built up of chapters with texts and various

  9. January 2002 volcano-tectonic eruption of Nyiragongo volcano, Democratic Republic of Congo

    NASA Astrophysics Data System (ADS)

    Tedesco, D.; Vaselli, O.; Papale, P.; Carn, S. A.; Voltaggio, M.; Sawyer, G. M.; Durieux, J.; Kasereka, M.; Tassi, F.

    2007-09-01

    In January 2002, Nyiragongo volcano erupted 14-34 × 106 m3 of lava from fractures on its southern flanks. The nearby city of Goma was inundated by two lava flows, which caused substantial socioeconomic disruption and forced the mass exodus of the population, leaving nearly 120,000 people homeless. Field observations showed marked differences between the lava erupted from the northern portion of the fracture system and that later erupted from the southern part. These observations are confirmed by new 238U and 232Th series radioactive disequilibria data, which show the presence of three different phases during the eruption. The lavas first erupted (T1) were probably supplied by a residual magma batch from the lava lake activity during 1994-1995. These lavas were followed by a fresh batch erupted from fissure vents as well as later (May-June 2002) from the central crater (T2). Both lava batches reached the surface via the volcano's central plumbing system, even though a separate flank reservoir may also have been involved in addition to the main reservoir. The final phase (T3) is related to an independent magmatic reservoir located much closer (or even beneath) the city of Goma. Data from the January 2002 eruption, and for similar activity in January 1977, suggest that the eruptive style of the volcano is likely to change in the future, trending toward more common occurrence of flank eruptions. If so, this would pose a significant escalation of volcanic hazards facing Goma and environs, thus requiring the implementation of different volcano-monitoring strategies to better anticipate where and when future eruptions might take place.

  10. Catalogue of Icelandic volcanoes

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Vogfjörd, Kristin; Tumi Gudmundsson, Magnus; Jonsson, Trausti; Oddsson, Björn; Reynisson, Vidir; Barsotti, Sara; Karlsdottir, Sigrun

    2015-04-01

    Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene. In the last 100 years, over 30 eruptions have occurred displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and their distribution. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in scientific papers and other publications. In 2010, the International Civil Aviation Organisation funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland (commenced in 2012), and the EU FP7 project FUTUREVOLC (2012-2016), establishing an Icelandic volcano Supersite. The Catalogue is a collaborative effort between the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Icelandic Civil Protection, with contributions from a large number of specialists in Iceland and elsewhere. The catalogue is scheduled for opening in the first half of 2015 and once completed, it will be an official publication intended to serve as an accurate and up to date source of information about active volcanoes in Iceland and their characteristics. The Catalogue is an open web resource in English and is composed of individual chapters on each of the volcanic systems. The chapters include information on the geology and structure of the volcano; the eruption history, pattern and products; the known precursory signals

  11. The Unexpected Awakening of Chaitén Volcano, Chile

    NASA Astrophysics Data System (ADS)

    Carn, Simon A.; Pallister, John S.; Lara, Luis; Ewert, John W.; Watt, Sebastian; Prata, Alfred J.; Thomas, Ronald J.; Villarosa, Gustavo

    2009-06-01

    On 2 May 2008, a large eruption began unexpectedly at the inconspicuous Chaitén volcano in Chile's southern volcanic zone. Ash columns abruptly jetted from the volcano into the stratosphere, followed by lava dome effusion and continuous low-altitude ash plumes [Lara, 2009]. Apocalyptic photographs of eruption plumes suffused with lightning were circulated globally. Effects of the eruption were extensive. Floods and lahars inundated the town of Chaitén, and its 4625 residents were evacuated. Widespread ashfall and drifting ash clouds closed regional airports and cancelled hundreds of domestic flights in Argentina and Chile and numerous international flights [Guffanti et al., 2008]. Ash heavily affected the aquaculture industry in the nearby Gulf of Corcovado, curtailed ecotourism, and closed regional nature preserves. To better prepare for future eruptions, the Chilean government has boosted support for monitoring and hazard mitigation at Chaitén and at 42 other highly hazardous, active volcanoes in Chile.

  12. Anatahan Volcano, Mariana Islands

    NASA Technical Reports Server (NTRS)

    2008-01-01

    In the early hours of February 7, ASTER captured this nighttime thermal infrared image of an eruption of Anatahan Volcano in the central Mariana Islands. The summit of the volcano is bright indicating there is a very hot area there. Streaming to the west is an ash plume, visible by the red color indicating the presence of silicate-rich particles. Dark grey areas are clouds that appear colder than the ocean. Anatahan is a stratovolcano that started erupting in May 2003, forming a new crater.

    The image covers an area of 56.3 x 41.8 km, and is located 16 degrees north latitude and 145.6 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  13. 4D volcano gravimetry

    USGS Publications Warehouse

    Battaglia, Maurizio; Gottsmann, J.; Carbone, D.; Fernandez, J.

    2008-01-01

    Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast (hours to weeks), as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera (California, U.S.A.) and Campi Flegrei (Italy), careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological inter-pretations, particularly when the real crust surrounding the source is far from the homogeneous/ isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located (e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography). Applications at Teide volcano (Tenerife) and Campi Flegrei demonstrate the

  14. Shiveluch and Klyuchevskaya Volcanoes

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A distance of about 80 kilometers (50 miles) separates Shiveluch and Klyuchevskaya Volcanoes on Russia's Kamchatka Peninsula. Despite this distance, however, the two acted in unison on April 26, 2007, when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite caught them both erupting simultaneously. ASTER 'sees' a slightly different portion of the light spectrum than human eyes. Besides a portion of visible light, ASTER detects thermal energy, meaning it can detect volcanic activity invisible to human eyes. Inset in each image above is a thermal infrared picture of the volcano's summit. In these insets, dark red shows where temperatures are coolest, and yellowish-white shows where temperatures are hottest, heated by molten lava. Both insets show activity at the crater. In the case of Klyuchevskaya, some activity at the crater is also visible in the larger image. In the larger images, the landscapes around the volcanoes appear in varying shades of blue-gray. Dark areas on the snow surface are likely stains left over from previous eruptions of volcanic ash. Overhead, clouds dot the sky, casting their shadows on the snow, especially southeast of Shiveluch and northeast of Klyuchevskaya. To the northwest of Klyuchevskaya is a large bank of clouds, appearing as a brighter white than the snow surface. Shiveluch (sometimes spelled Sheveluch) and Klyuchevskaya (sometimes spelled Klyuchevskoy or Kliuchevskoi) are both stratovolcanoes composed of alternating layers of hardened lava, solidified ash, and rocks from earlier eruptions. Both volcanoes rank among Kamchatka's most active. Because Kamchatka is part of the Pacific 'Ring of Fire,' the peninsula experiences regular seismic activity as the Pacific Plate slides below other tectonic plates in the Earth's crust. Large-scale plate tectonic activity causing simultaneous volcanic eruptions in Kamchatka is not uncommon.

  15. Volcanoes and climate

    NASA Technical Reports Server (NTRS)

    Toon, O. B.

    1982-01-01

    The evidence that volcanic eruptions affect climate is reviewed. Single explosive volcanic eruptions cool the surface by about 0.3 C and warm the stratosphere by several degrees. Although these changes are of small magnitude, there have been several years in which these hemispheric average temperature changes were accompanied by severely abnormal weather. An example is 1816, the "year without summer" which followed the 1815 eruption of Tambora. In addition to statistical correlations between volcanoes and climate, a good theoretical understanding exists. The magnitude of the climatic changes anticipated following volcanic explosions agrees well with the observations. Volcanoes affect climate because volcanic particles in the atmosphere upset the balance between solar energy absorbed by the Earth and infrared energy emitted by the Earth. These interactions can be observed. The most important ejecta from volcanoes is not volcanic ash but sulfur dioxide which converts into sulfuric acid droplets in the stratosphere. For an eruption with its explosive magnitude, Mount St. Helens injected surprisingly little sulfur into the stratosphere. The amount of sulfuric acid formed is much smaller than that observed following significant eruptions and is too small to create major climatic shifts. However, the Mount St. Helens eruption has provided an opportunity to measure many properties of volcanic debris not previously measured and has therefore been of significant value in improving our knowledge of the relations between volcanic activity and climate.

  16. Volcanoes generate devastating waves

    SciTech Connect

    Lockridge, P. )

    1988-01-01

    Although volcanic eruptions can cause many frightening phenomena, it is often the power of the sea that causes many volcano-related deaths. This destruction comes from tsunamis (huge volcano-generated waves). Roughly one-fourth of the deaths occurring during volcanic eruptions have been the result of tsunamis. Moreover, a tsunami can transmit the volcano's energy to areas well outside the reach of the eruption itself. Some historic records are reviewed. Refined historical data are increasingly useful in predicting future events. The U.S. National Geophysical Data Center/World Data Center A for Solid Earth Geophysics has developed data bases to further tsunami research. These sets of data include marigrams (tide gage records), a wave-damage slide set, digital source data, descriptive material, and a tsunami wall map. A digital file contains information on methods of tsunami generation, location, and magnitude of generating earthquakes, tsunami size, event validity, and references. The data can be used to describe areas mot likely to generate tsunamis and the locations along shores that experience amplified effects from tsunamis.

  17. The eruption of Redoubt Volcano, Alaska, December 14,1989-August 31, 1990

    SciTech Connect

    Brantley, S.R.

    1990-12-01

    This paper reports on explosive volcanic activity at Redoubt Volcano, 177 km southwest of Anchorage, Alaska, which generated numerous tephra plumes that disrupted air traffic above southern Alaska, damaged aircraft, and caused locally heavy tephra fall. Pyroclastic flows triggered debris flows that inundated part of an oil-tanker facility, temporarily suspending oil production in Cook Inlet. The newly established Alaska Volcano Observatory increased its monitoring effort and disseminated volcanic hazard information to government agencies, industry, and the public.

  18. Eruptions of Eyjafjallajökull Volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Magnús T.; Pedersen, Rikke; Vogfjörd, Kristín; Thorbjarnardóttir, Bergthóra; Jakobsdóttir, Steinunn; Roberts, Matthew J.

    2010-05-01

    The April 2010 eruption of Eyjafjallajökull volcano (Figure 1), located on Iceland's southern coast, created unprecedented disruptions to European air traffic during 15-20 April, costing the aviation industry an estimated $250 million per day (see the related news item in this issue). This cost brings into focus how volcanoes can affect communities thousands of miles away. Eyjafjallajökull rises to 1666 meters above sea level and hosts agricultural land on its southern slopes, with farms located as close as 7 kilometers from the summit caldera. In the past 1500 years, Eyjafjallajökull has produced four comparatively small eruptions. The eruption previous to 2010 began in December 1821 and lasted for over a year, with intermittent explosive activity spreading a thin layer of tephra (ash and larger ejected clasts) over the surrounding region. In contrast, the explosive 2010 eruption, sourced within the ice-capped summit of the volcano, so far is larger and characterized by magma of a slightly different composition. This may suggest that deep within the volcano, the 1821 magma source is mixing with new melt, or that residual melt from past intrusive events is being pushed out by new magma.

  19. Digital Data for Volcano Hazards at Newberry Volcano, Oregon

    USGS Publications Warehouse

    Schilling, S.P.; Doelger, S.; Sherrod, D.R.; Mastin, L.G.; Scott, W.E.

    2008-01-01

    Newberry volcano is a broad shield volcano located in central Oregon, the product of thousands of eruptions, beginning about 600,000 years ago. At least 25 vents on the flanks and summit have been active during the past 10,000 years. The most recent eruption 1,300 years ago produced the Big Obsidian Flow. Thus, the volcano's long history and recent activity indicate that Newberry will erupt in the future. Newberry Crater, a volcanic depression or caldera has been the focus of Newberry's volcanic activity for at least the past 10,000 years. Newberry National Volcanic Monument, which is managed by the U.S. Forest Service, includes the caldera and extends to the Deschutes River. Newberry volcano is quiet. Local earthquake activity (seismicity) has been trifling throughout historic time. Subterranean heat is still present, as indicated by hot springs in the caldera and high temperatures encountered during exploratory drilling for geothermal energy. The report USGS Open-File Report 97-513 (Sherrod and others, 1997) describes the kinds of hazardous geologic events that might occur in the future at Newberry volcano. A hazard-zonation map is included to show the areas that will most likely be affected by renewed eruptions. When Newberry volcano becomes restless, the eruptive scenarios described herein can inform planners, emergency response personnel, and citizens about the kinds and sizes of events to expect. The geographic information system (GIS) volcano hazard data layers used to produce the Newberry volcano hazard map in USGS Open-File Report 97-513 are included in this data set. Scientists at the USGS Cascades Volcano Observatory created a GIS data layer to depict zones subject to the effects of an explosive pyroclastic eruption (tephra fallout, pyroclastic flows, and ballistics), lava flows, volcanic gasses, and lahars/floods in Paulina Creek. A separate GIS data layer depicts drill holes on the flanks of Newberry Volcano that were used to estimate the probability

  20. Volcano-tectonic evolution of the polygenetic Kolumbo submarine volcano/Santorini (Aegean Sea)

    NASA Astrophysics Data System (ADS)

    Hübscher, Christian; Ruhnau, M.; Nomikou, P.

    2015-01-01

    Here we show for the first time the 3D-structural evolution of an explosive submarine volcano by means of reflection seismic interpretation. Four to five vertically stacked circular and cone-shaped units consisting mainly of volcaniclastics build the Kolumbo underwater volcano which experienced its first eruption > 70 ka ago and its last explosive eruption 1650 AD, 7 km NE of Santorini volcano (southern Aegean Sea). The summed volume of volcaniclastics is estimated to range between 13-22 km3. The entire Kolumbo volcanic complex has a height of ≥ 1 km and a diameter of ≥ 11 km. All volcaniclastic units reveal the same transparent reflection pattern strongly suggesting that explosive underwater volcanism was the prevalent process. Growth faults terminate upwards at the base of volcaniclastic units, thus representing a predictor to an eruption phase. Similarities in seismic reflection pattern between Kolumbo and near-by volcanic cones imply that the smaller cones evolved through explosive eruptions as well. Hence, the central Aegean Sea experienced several more explosive eruptions (≥ 23) than previously assumed, thus justifying further risk assessment. However, the eruption columns from the smaller volcanic cones did not reach the air and- consequently - no sub-aerial pyroclastic surge was created. The Anydros basin that hosts Kolumbo volcanic field opened incrementally NW to SE and parallel to the Pliny and Strabo trends during four major tectonic pulses prior to the onset of underwater volcanism.

  1. Remote sensing of Italian volcanos

    NASA Technical Reports Server (NTRS)

    Bianchi, R.; Casacchia, R.; Coradini, A.; Duncan, A. M.; Guest, J. E.; Kahle, A.; Lanciano, P.; Pieri, D. C.; Poscolieri, M.

    1990-01-01

    The results of a July 1986 remote sensing campaign of Italian volcanoes are reviewed. The equipment and techniques used to acquire the data are described and the results obtained for Campi Flegrei and Mount Etna are reviewed and evaluated for their usefulness for the study of active and recently active volcanoes.

  2. Volcanoes, Central Java, Indonesia

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The island of Java (8.0S, 112.0E), perhaps better than any other, illustrates the volcanic origin of Pacific Island groups. Seen in this single view are at least a dozen once active volcano craters. Alignment of the craters even defines the linear fault line of Java as well as the other some 1500 islands of the Indonesian Archipelago. Deep blue water of the Indian Ocean to the south contrasts to the sediment laden waters of the Java Sea to the north.

  3. Volcanoes of the Solar System

    NASA Astrophysics Data System (ADS)

    Frankel, Charles

    1996-09-01

    Nothing can be more breathtaking than the spectacle of a volcano erupting. Space-age lunar and planetary missions offer us an unprecedented perspective on volcanism. Starting with the Earth, Volcanoes of the Solar System takes the reader on a guided tour of the terrestrial planets and moons and their volcanic features. We see lunar lava fields through the eyes of the Apollo astronauts, and take an imaginary hike up the Martian slopes of Olympus Mons--the tallest volcano in the solar system. Complemented by over 150 photographs, this comprehensive and lucid account of volcanoes describes the most recent data on the unique and varied volcanic features of Venus and updates our knowledge on the prodigiously active volcanoes of Io. A member of the Association of European Volcanologists, Charles Frankel has directed documentary films on geology, astronomy and space exploration and has authored a number of articles on the earth sciences.

  4. A transect of Tertiary central volcanoes across northwest Iceland

    NASA Astrophysics Data System (ADS)

    Jordan, B. T.; Duncan, R. A.; Carley, T. L.

    2013-12-01

    The Skagi-Snaefellsnes rift zone (SSRZ) was the focus of rifting in Iceland from ~15-7 Ma. We report on a transect of central volcanoes and isolated exposures of silicic rocks erupted from the SSRZ in northwest Iceland. The youngest system investigated is an epizonal intrusive series, gabbro to granite, at the northern end of Vididalsfjall, near the axis of the SSRZ. The granite yields an Ar/Ar plateau age of 7.03 × 0.07 Ma (all dates ×2σ), and SHRIMP 206Pb/238U zircon analysis gives an age of 6.79 × 0.35 Ma (n=15). This represents the final silicic activity in the northern SSRZ prior to abandonment at this latitude. Just east of the SSRZ is a central volcano exposed in Vatnsdalsfjall, Langadalsfjall, and Laxardalsfjoll, informally termed the southern Skagi central volcano. Ar/Ar ages for intermediate to silicic rocks in this system include a 7.62 × 0.32 Ma dacite, 7.80 × 0.07 Ma andesite, and a 7.82 × 0.04 Ma rhyolite. The rhyolite was also dated by SHRIMP zircon analysis yielding an age of 7.62 × 0.29 Ma (n=19). The Arnes central volcano is exposed on the northeastern tip of the West Fjords peninsula, east of the SSRZ. Based on correlation with nearby dated paleomagnetic surveys the age is ~12 Ma. The Hrafnfjordur central volcano further west in the West Fjords may be the oldest central volcano exposed on land in Iceland. A SHRIMP zircon age for the main dacite lava is 14.16 × 0.40 Ma (n=14). The three central volcanoes feature nearly continuous compositional spectra from basalt to a high-silica dacite or rhyolite. Extensive rhyolites occur in southern Skagi and Arnes, but with 2/3 of the system mapped, there are no true rhyolites at Hrafnfjordur; the most extensive silicic unit is a dacite lava (65-70 wt.% SiO2). Variation in Zr vs. SiO2 seems to implicate a cryptic high-silica low-Zr rhyolite magma as an end-member of mixing for some andesites at Hrafnfjordur, but Zr/Ti disproves this. The origin of most of the silicic magmas is likely by crustal

  5. Volcanic Lightning in Eruptions of Sakurajima Volcano

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  6. Elysium Mons Volcano

    NASA Technical Reports Server (NTRS)

    1998-01-01

    On July 4, 1998--the first anniversary of the Mars Pathfinder landing--Mars Global Surveyor's latest images were radioed to Earth with little fanfare. The images received on July 4, 1998, however, were very exciting because they included a rare crossing of the summit caldera of a major martian volcano. Elysium Mons is located at 25oN, 213oW, in the martian eastern hemisphere. Elysium Mons is one of three large volcanoes that occur on the Elysium Rise-- the others are Hecates Tholus (northeast of Elysium Mons) and Albor Tholus (southeast of Elysium Mons). The volcano rises about 12.5 kilometers (7.8 miles) above the surrounding plain, or about 16 kilometers (9.9 miles) above the martian datum-- the 'zero' elevation defined by average martian atmospheric pressure and the planet's radius.

    Elysium Mons was discovered by Mariner 9 in 1972. It differs in a number of ways from the familiar Olympus Mons and other large volcanoes in the Tharsis region. In particular, there are no obvious lava flows visible on the volcano's flanks. The lack of lava flows was apparent from the Mariner 9 images, but the new MOC high resolution image--obtained at 5.24 meters (17.2 feet) per pixel--illustrates that this is true even when viewed at higher spatial resolution.

    Elysium Mons has many craters on its surface. Some of these probably formed by meteor impact, but many show no ejecta pattern characteristic of meteor impact. Some of the craters are aligned in linear patterns that are radial to the summit caldera--these most likely formed by collapse as lava was withdrawn from beneath the surface, rather than by meteor impact. Other craters may have formed by explosive volcanism. Evidence for explosive volcanism on Mars has been very difficult to identify from previous Mars spacecraft images. This and other MOC data are being examined closely to better understand the nature and origin of volcanic features on Mars.

    The three MOC images, 40301 (red wide angle), 40302 (blue wide angle

  7. New geophysical views of Mt.Melbourne Volcano (East Antarctica)

    NASA Astrophysics Data System (ADS)

    Armadillo, E.; Gambetta, M.; Ferraccioli, F.; Corr, H.; Bozzo, E.

    2009-05-01

    Mt. Melbourne volcano is located along the transition between the Transantarctic Mountains and the West Antarctic Rift System. Recent volcanic activity is suggested by the occurrence of blankets of pyroclastic pumice and scoria fall around the eastern and southern flanks of Mt Melbourne and by pyroclastic layers interbedded with the summit snows. Geothermal activity in the crater area of Mount Melbourne may be linked to the intrusion of dykes within the last 200 years. Geophysical networks suggest that Mount Melbourne is a quiescent volcano, possibly characterised by slow internal dynamics. During the 2002-2003 Italian Antarctic campaign a high-resolution aeromagnetic survey was performed within the TIMM (Tectonics and Interior of Mt. Melbourne area) project. This helicopter-borne survey was flown at low-altitude and in drape-mode configuration (305 m above terrain) with a line separation less than 500 m. Our new high-resolution magnetic maps reveal the largely ice-covered magmatic and tectonic patters in the Mt. Melbourne volcano area. Additionally, in the frame of the UK-Italian ISODYN-WISE project (2005-06), an airborne ice-sounding radar survey was flown. We combine the sub-ice topography with images and models of the interior of Mt. Melbourne volcano, as derived from the high resolution aeromagnetic data and land gravity data. Our new geophysical maps and models also provide a new tool to study the regional setting of the volcano. In particular we re-assess whether there is geophysical evidence for coupling between strike-slip faulting, the Terror Rift, and Mount Melbourne volcano.

  8. Mount Rainier active cascade volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  9. Eruptive viscosity and volcano morphology

    NASA Technical Reports Server (NTRS)

    Posin, Seth B.; Greeley, Ronald

    1988-01-01

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

  10. Volcano spacing and plate rigidity

    SciTech Connect

    Brink, U. )

    1991-04-01

    In-plane stresses, which accompany the flexural deformation of the lithosphere under the load adjacent volcanoes, may govern the spacing of volcanoes in hotspot provinces. Specifically, compressive stresses in the vicinity of a volcano prevent new upwelling in this area, forcing a new volcano to develop at a minimum distance that is equal to the distance in which the radial stresses change from compressional to tensile (the inflection point). If a volcano is modeled as a point load on a thin elastic plate, then the distance to the inflection point is proportional to the thickness of the plate to the power of 3/4. Compilation of volcano spacing in seven volcanic groups in East Africa and seven volcanic groups of oceanic hotspots shows significant correlation with the elastic thickness of the plate and matches the calculated distance to the inflection point. In contrast, volcano spacing in island arcs and over subduction zones is fairly uniform and is much larger than predicted by the distance to the inflection point, reflecting differences in the geometry of the source and the upwelling areas.

  11. Soufriere Hills Volcano

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this ASTER image of Soufriere Hills Volcano on Montserrat in the Caribbean, continued eruptive activity is evident by the extensive smoke and ash plume streaming towards the west-southwest. Significant eruptive activity began in 1995, forcing the authorities to evacuate more than 7,000 of the island's original population of 11,000. The primary risk now is to the northern part of the island and to the airport. Small rockfalls and pyroclastic flows (ash, rock and hot gases) are common at this time due to continued growth of the dome at the volcano's summit.

    This image was acquired on October 29, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

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

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is

  12. Counterfactual Volcano Hazard Analysis

    NASA Astrophysics Data System (ADS)

    Woo, Gordon

    2013-04-01

    , if a major storm surge happens to arrive at a high astronomical tide, sea walls may be overtopped and flooding may ensue. In the domain of geological hazards, periods of volcanic unrest may generate precursory signals suggestive of imminent volcanic danger, but without leading to an actual eruption. Near-miss unrest periods provide vital evidence for assessing the dynamics of volcanoes close to eruption. Where the volcano catalogue has been diligently revised to include the maximum amount of information on the phenomenology of unrest periods, dynamic modelling and hazard assessment may be significantly refined. This is illustrated with some topical volcano hazard examples, including Montserrat and Santorini.

  13. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, Robert I.

    1987-01-01

    One of the most spectacular, awesomely beautiful, and at times destructive displays of natural energy is an erupting volcano, belching fume and ash thousands of meters into the atmosphere and pouring out red-hot molten lava in fountains and streams. Countless eruptions in the geologic past have produced volcanic rocks that form much of the Earth's present surface. The gradual disintegration and weathering of these rocks have yielded some of the richest farmlands in the world, and these fertile soils play a significant role in sustaining our large and growing population. Were it not for volcanic activity, the Hawaiian Islands with their sugar cane and pineapple fields and magnificent landscapes and seascapes would not exist to support their residents and to charm their visitors. Yet, the actual eruptive processes are catastrophic and can claim life and property.

  14. Active submarine volcano sampled

    USGS Publications Warehouse

    Taylor, B.

    1983-01-01

    On June 4, 1982, two full dredge hauls of fresh lava were recovered from the upper flanks of Kavachi submarine volcano, Solomon Islands, in the western Pacific Ocean, from the water depths of 1,200 and 2,700 feet. the shallower dredge site was within 0.5 mile of the active submarine vent shown at the surface by an area of slick water, probably caused by gas emissions. Kavachi is a composite stratovolcano that has been observed to erupt every year or two for at least the last 30 years (see photographs). An island formed in 1952, 1961, 1965, and 1978; but, in each case, it rapidly eroded below sea level. The latest eruption was observed by Solair pilots during the several weeks up to and including May 18, 1982. 

  15. Volcanoes, Third Edition

    NASA Astrophysics Data System (ADS)

    Nye, Christopher J.

    It takes confidence to title a smallish book merely “Volcanoes” because of the impliction that the myriad facets of volcanism—chemistry, physics, geology, meteorology, hazard mitigation, and more—have been identified and addressed to some nontrivial level of detail. Robert and Barbara Decker have visited these different facets seamlessly in Volcanoes, Third Edition. The seamlessness comes from a broad overarching, interdisciplinary, professional understanding of volcanism combined with an exceptionally smooth translation of scientific jargon into plain language.The result is a book which will be informative to a very broad audience, from reasonably educated nongeologists (my mother loves it) to geology undergraduates through professional volcanologists. I bet that even the most senior professional volcanologists will learn at least a few things from this book and will find at least a few provocative discussions of subjects they know.

  16. HSDP: The Lost Volcano

    NASA Astrophysics Data System (ADS)

    Blichert-Toft, J.; Albarede, F.

    2008-12-01

    We measured high-precision Hf, Nd, and Pb isotope compositions for 40 samples from the final leg of the Hawaii Scientific Drilling Project (HSDP) core using solution chemistry and MC-ICP-MS. This final leg extends the drill core from 3097.7 mbsl down to a depth of 3505.7 mbsl. The new isotope data are indistinguishable from those higher up in the Mauna Kea part of the core and vary from, respectively, +11.6 to +12.3, +6.4 to +7.0, and 18.2948 to 18.6819 for ɛHf, ɛNd, and 206Pb/204Pb. The Pb isotope data define three linear trends with a common intersection. Principal component analysis recognizes no more than three geochemical end-members (99.8% of the variance) among these trends. When all the Pb isotope data acquired so far ([1-3] and this work) are pooled, two contrasting groups stand out, mostly with respect to 208Pb/206Pb. (1) A first coherent, prevalent group is identified, which represents the Kea main eruptive sequence. This group combines the Kea-mid8 and the Kea-lo8 subgroups of [3]: although these subgroups define two separate trends in Pb-Pb isotope space, they smoothly follow each other in time. (2) A second group of 15 flows at depths below 2000 mbsl is characterized by distinctly higher source Th/U and, for the samples above the new core samples, also high 3He/4He. These samples belong to the K/L group of [2] and to the Kea-hi8 group of [3] and are about 0.4 (Hf) and 0.5 (Nd) ɛ units below the main sequence Kea values. The toggle between these two groups of flows is so sharp and repetitive and the gap between the values so conspicuous that the alternation must reflect eruptions from distinct volcanic centers, Mauna Kea and an unknown volcano (K/L) that bears some isotopic resemblance to Kilauea for Nd and Hf and to Loihi for He [2, 4]. This 'lost' volcano stopped erupting about 550 ka ago, i.e., 200 ka before the oldest ages known for Kilauea [5], and is presently buried under 2-3000 m of Mauna Kea flows. We left out the data on the lost volcano

  17. Living with volcanoes

    USGS Publications Warehouse

    Wright, Thomas L.; Pierson, Thomas C.

    1992-01-01

    The 1980 cataclysmic eruption of Mount St. Helens (Lipman and Mullineaux, 1981) in southwestern Washington ushered in a decade marked by more worldwide volcanic disasters and crises than any other in recorded history. Volcanoes killed more people (over 28,500) in the 1980's than during the 78 years following 1902 eruption of Mount Pelee (Martinique). Not surprisingly, volcanic phenomena and attendant hazards received attention from government authorities, the news media, and the general public. As part of this enhanced global awareness of volcanic hazards, the U.S. Geological Survey (Bailey and others, 1983) in response to the eruptions or volcanic unrest during the 1980's at Mount St. Helens and Redoubt are still erupting intermittently, and the caldera unrest at Long Valley also continues, albeit less energetically than during the early 1980's.

  18. A magmatic model of Medicine Lake Volcano, California ( USA).

    USGS Publications Warehouse

    Donnelly-Nolan, J. M.

    1988-01-01

    Medicine Lake volcano is a Pleistocene and Holocene shield volcano of the southern Cascade Range. It is located behind the main Cascade arc in an extensional tectonic setting where high-alumina basalt is the most commonly erupted lava. This basalt is parental to the higher-silica calc-alkaline and tholeiitic lavas that make up the bulk of the shield. The presence of late Holocene, chemically identical rhyolites on opposite sides of the volcano led to hypotheses of a large shallow silicic magma chamber and of a small, deep chamber that fed rhyolites to the surface via cone sheets. Subsequent geophysical work has been unable to identify a large silicic magma body, and instead a small one has apparently been recognized. Some geologic data support the geophysical results. Tectonic control of vent alignments and the dominance of mafic eruptions both in number of events and volume throughout the history of the volcano indicate that no large silicic magma reservoir exists. Instead, a model is proposed that includes numerous dikes, sills and small magma bodies, most of which are too small to be recognized by present geophysical methods.-Author

  19. Flank tectonics of Martian volcanoes

    NASA Technical Reports Server (NTRS)

    Thomas, Paul J.; Squyres, Steven W.; Carr, Michael H.

    1990-01-01

    The origin of the numerous terraces on the flanks of the Olympus Mons volcano on Mars, seen on space images to be arranged in a roughly concentric pattern, is investigated. The images of the volcano show that the base of each terrace is marked by a modest but abrupt change in slope, suggesting that these terraces could be thrust faults caused by a compressional failure of the cone. The mechanism of faulting and the possible effect of the interior structure of Olympus Mons was investigated using a numerical model for elastic stresses within a Martian volcano, constructed for that purpose. Results of the analysis supports the view that the terraces on Olympus Mons, as well as on other three Martian volcanoes, including Ascraeus Mons, Arsia Mons, and Pavonis Mons are indeed thrust faults.

  20. Morphometric evolution of composite volcanoes

    NASA Technical Reports Server (NTRS)

    Wood, C. A.

    1978-01-01

    Statistical relations between geometry, slope, and age for 26 circum-Pacific composite volcanoes (stratovolcanoes) are presented. Topics considered include morphometry, eruption characteristics, growth rates, repose periods, flow lengths, and petrological/chemical trends. Composite and cinder cones are compared, and it is suggested that, if cinder cones do evolve into composite volcanoes, a fundamental change in cone morphometry, eruption style, and petrology occurs at a basal diameter of 2 km.

  1. Mount St. Helens and Kilauea volcanoes

    SciTech Connect

    Barrat, J. )

    1989-01-01

    Mount St. Helens' eruption has taught geologists invaluable lessons about how volcanoes work. Such information will be crucial in saving lives and property when other dormant volcanoes in the northwestern United States--and around the world--reawaken, as geologists predict they someday will. Since 1912, scientists at the U.S. Geological Survey's Hawaiian Volcano Observatory have pioneered the study of volcanoes through work on Mauna Loa and Kilauea volcanoes on the island of Hawaii. In Vancouver, Wash., scientists at the Survey's Cascades Volcano Observatory are studying the after-effects of Mount St. Helens' catalysmic eruption as well as monitoring a number of other now-dormant volcanoes in the western United States. This paper briefly reviews the similarities and differences between the Hawaiian and Washington volcanoes and what these volcanoes are teaching the volcanologists.

  2. Numerical simulation of tsunami generation by cold volcanic mass flows at Augustine Volcano, Alaska

    USGS Publications Warehouse

    Waythomas, C.F.; Watts, P.; Walder, J.S.

    2006-01-01

    Many of the world's active volcanoes are situated on or near coastlines. During eruptions, diverse geophysical mass flows, including pyroclastic flows, debris avalanches, and lahars, can deliver large volumes of unconsolidated debris to the ocean in a short period of time and thereby generate tsunamis. Deposits of both hot and cold volcanic mass flows produced by eruptions of Aleutian arc volcanoes are exposed at many locations along the coastlines of the Bering Sea, North Pacific Ocean, and Cook Inlet, indicating that the flows entered the sea and in some cases may have initiated tsunamis. We evaluate the process of tsunami generation by cold granular subaerial volcanic mass flows using examples from Augustine Volcano in southern Cook Inlet. Augustine Volcano is the most historically active volcano in the Cook Inlet region, and future eruptions, should they lead to debris-avalanche formation and tsunami generation, could be hazardous to some coastal areas. Geological investigations at Augustine Volcano suggest that as many as 12-14 debris avalanches have reached the sea in the last 2000 years, and a debris avalanche emplaced during an A.D. 1883 eruption may have initiated a tsunami that was observed about 80 km east of the volcano at the village of English Bay (Nanwalek) on the coast of the southern Kenai Peninsula. Numerical simulation of mass-flow motion, tsunami generation, propagation, and inundation for Augustine Volcano indicate only modest wave generation by volcanic mass flows and localized wave effects. However, for east-directed mass flows entering Cook Inlet, tsunamis are capable of reaching the more populated coastlines of the southwestern Kenai Peninsula, where maximum water amplitudes of several meters are possible.

  3. Continuous in-situ Measurements of Gases (H2, H2S, CH4, N2, O2, Ar, He, and CO2) at the Fumarole "Soffionissimo" (Solfatara volcano, Southern Italy)

    NASA Astrophysics Data System (ADS)

    Wiersberg, T.; Somma, R.; Rocco, A.; de Rosa, M.; Zimmer, M.; Quattrocchi, F.; de Natale, G.; de Natale, P.

    2007-05-01

    From November 29th to December 1st 2006, a gas monitoring experiment was carried out at the Solfatara volcano (Pozzuoli, Italy). The primary objectives were to prove that monitoring is possible with the experimental set-up described below, and to compare the new data obtained with those from earlier continuos gas monitoring carried out in November 2001. Temperature measurements and gas extraction were done at the fumarole "Soffionissimo" very close to the "Bocca Grande". The temperature measurements were performed with a temperature probe (K-type thermocouple), which was let about 30 cm into the fumarole. For better comparison of temperature and gas data, the gas tube was directly connected with the temperature probe. After having adjusted a continuous gas flow with a diaphragm pump and a needle valve, the gas was piped through a 10 m Teflon© tube for more than 40 hours. The gas phase primary consists of water gas, which was condensed in a trap, installed in a refrigerator. The amount of water in the trap was determined regulary every 3-4 hours. At the beginning of the monitoring experiment, the Teflon© tube was heated in order to avoid condensation of the water in the tube before getting trapped. Although the tube was not heated for the whole time of the experiment, it turns out that the amount of water, condensed in the water trap per hour, and does not significantly change when the tube was not heated. Hence, the amount of water, condensing in the tube before getting trapped, seems negligible. The remaining, almost water-free gas phase was finally dried over Fe wool in a filter, and then continuously analysed with a quadrupole mass spectrometer (Balzers Omnistar ©) for the following components: H2, H2S, CH4, N2, O2, Ar, He, and CO2. To make sure that the final drying process does not influence the gas composition in particular for H2 and H2S, a comparison measurement was done without the filter, which only revealed somewhat higher water content. During the

  4. Digital Geologic Map Database of Medicine Lake Volcano, Northern California

    NASA Astrophysics Data System (ADS)

    Ramsey, D. W.; Donnelly-Nolan, J. M.; Felger, T. J.

    2010-12-01

    Medicine Lake volcano, located in the southern Cascades ~55 km east-northeast of Mount Shasta, is a large rear-arc, shield-shaped volcano with an eruptive history spanning nearly 500 k.y. Geologic mapping of Medicine Lake volcano has been digitally compiled as a spatial database in ArcGIS. Within the database, coverage feature classes have been created representing geologic lines (contacts, faults, lava tubes, etc.), geologic unit polygons, and volcanic vent location points. The database can be queried to determine the spatial distributions of different rock types, geologic units, and other geologic and geomorphic features. These data, in turn, can be used to better understand the evolution, growth, and potential hazards of this large, rear-arc Cascades volcano. Queries of the database reveal that the total area covered by lavas of Medicine Lake volcano, which range in composition from basalt through rhyolite, is about 2,200 km2, encompassing all or parts of 27 U.S. Geological Survey 1:24,000-scale topographic quadrangles. The maximum extent of these lavas is about 80 km north-south by 45 km east-west. Occupying the center of Medicine Lake volcano is a 7 km by 12 km summit caldera in which nestles its namesake, Medicine Lake. The flanks of the volcano, which are dotted with cinder cones, slope gently upward to the caldera rim, which reaches an elevation of nearly 2,440 m. Approximately 250 geologic units have been mapped, only half a dozen of which are thin surficial units such as alluvium. These volcanic units mostly represent eruptive events, each commonly including a vent (dome, cinder cone, spatter cone, etc.) and its associated lava flow. Some cinder cones have not been matched to lava flows, as the corresponding flows are probably buried, and some flows cannot be correlated with vents. The largest individual units on the map are all basaltic in composition, including the late Pleistocene basalt of Yellowjacket Butte (296 km2 exposed), the largest unit on the

  5. Multiple Active Volcanoes in the Northeast Lau Basin

    NASA Astrophysics Data System (ADS)

    Baker, E. T.; Resing, J. A.; Lupton, J. E.; Walker, S. L.; Embley, R. W.; Rubin, K. H.; Buck, N.; de Ronde, C. E.; Arculus, R. J.

    2010-12-01

    The northeast Lau Basin occupies a complex geological area between the Tafua arc front, the E-W trending Tonga Trench, and the Northeast Lau Spreading Center. These boundaries create multiple zones of extension and thus provide abundant opportunities for magma to invade the crust. The 25-km-long chain of “Mata” volcanoes lies near the center of this area, separated from both the arc front and the spreading ridge. In 2008 we discovered hydrothermal venting on the largest and most southerly of these volcanoes, W and E Mata. In 2010 we visited the 7 smaller volcanoes that form a 15-km-long arcuate sweep to the north from W and E Mata (the “North Matas”). We also revisited W and E Mata. Over each volcano we conducted CTD tows to map plumes and collect water samples. Based on the CTD results, camera tows searched for seafloor sources on three volcanoes. The N Mata volcanoes, extending from Mata Taha (1) in the south to Mata Fitu (7) in the north, lie within a prominent gap in the shallow bathymetry along the southern border of the Tonga trench. Northward from E Mata the Mata volcanoes degrade from large symmetrical cones to smaller and blocky volcanic edifices. Summit depths range from 1165 m (W Mata) to 2670 m (Mata Nima (5)). The most active volcano in the chain is the erupting W Mata, with an intense plume that extended 250 m above the summit. Hydrothermal temperature anomalies (Δθ, corrected for hydrographic masking effects) reached ˜1.7°C, with light-scattering values as high as 2-5 ΔNTU. The 2010 surveys now show that 6 of the 7 N Mata volcanoes are also hydrothermally active. Along the N Matas, Δθ and ΔNTU signals ranged from robust to weak, but distinct oxidation-reduction potential (aka Eh) anomalies confirmed active venting in each case. The most concentrated plumes were found near Mata Ua (2) and Mata Fitu (7), with Δθ and ΔNTU maxima of 0.1-0.17°C and 0.3, respectively. Despite the variability in plume strength, however, ΔNTU/Δθ ratios

  6. Vertical Motions of Oceanic Volcanoes

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Moore, J. G.

    2006-12-01

    Oceanic volcanoes offer abundant evidence of changes in their elevations through time. Their large-scale motions begin with a period of rapid subsidence lasting hundreds of thousands of years caused by isostatic compensation of the added mass of the volcano on the ocean lithosphere. The response is within thousands of years and lasts as long as the active volcano keeps adding mass on the ocean floor. Downward flexure caused by volcanic loading creates troughs around the growing volcanoes that eventually fill with sediment. Seismic surveys show that the overall depression of the old ocean floor beneath Hawaiian volcanoes such as Mauna Loa is about 10 km. This gross subsidence means that the drowned shorelines only record a small part of the total subsidence the islands experienced. In Hawaii, this history is recorded by long-term tide-gauge data, the depth in drill holes of subaerial lava flows and soil horizons, former shorelines presently located below sea level. Offshore Hawaii, a series of at least 7 drowned reefs and terraces record subsidence of about 1325 m during the last half million years. Older sequences of drowned reefs and terraces define the early rapid phase of subsidence of Maui, Molokai, Lanai, Oahu, Kauai, and Niihau. Volcanic islands, such as Maui, tip down toward the next younger volcano as it begins rapid growth and subsidence. Such tipping results in drowned reefs on Haleakala as deep as 2400 m where they are tipped towards Hawaii. Flat-topped volcanoes on submarine rift zones also record this tipping towards the next younger volcano. This early rapid subsidence phase is followed by a period of slow subsidence lasting for millions of years caused by thermal contraction of the aging ocean lithosphere beneath the volcano. The well-known evolution along the Hawaiian chain from high to low volcanic island, to coral island, and to guyot is due to this process. This history of rapid and then slow subsidence is interrupted by a period of minor uplift

  7. Chiliques volcano, Chile

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A January 6, 2002 ASTER nighttime thermal infrared image of Chiliques volcano in Chile shows a hot spot in the summit crater and several others along the upper flanks of the edifice, indicating new volcanic activity. Examination of an earlier nighttime thermal infrared image from May 24,2000 showed no thermal anomaly. Chiliques volcano was previously thought to be dormant. Rising to an elevation of 5778 m, Chiliques is a simple stratovolcano with a 500-m-diameter circular summit crater. This mountain is one of the most important high altitude ceremonial centers of the Incas. It is rarely visited due to its difficult accessibility. Climbing to the summit along Inca trails, numerous ruins are encountered; at the summit there are a series of constructions used for rituals. There is a beautiful lagoon in the crater that is almost always frozen.

    The daytime image was acquired on November 19, 2000 and was created by displaying ASTER bands 1,2 and 3 in blue, green and red. The nighttime image was acquired January 6, 2002, and is a color-coded display of a single thermal infrared band. The hottest areas are white, and colder areas are darker shades of red. Both images cover an area of 7.5 x 7.5 km, and are centered at 23.6 degrees south latitude, 67.6 degrees west longitude.

    Both images cover an area of 7.5 x 7.5 km, and are centered at 23.6 degrees south latitude, 67.6 degrees west longitude.

    These images were acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A

  8. Northern Arizona Volcanoes

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Northern Arizona is best known for the Grand Canyon. Less widely known are the hundreds of geologically young volcanoes, at least one of which buried the homes of local residents. San Francisco Mtn., a truncated stratovolcano at 3887 meters, was once a much taller structure (about 4900 meters) before it exploded some 400,000 years ago a la Mt. St. Helens. The young cinder cone field to its east includes Sunset Crater, that erupted in 1064 and buried Native American homes. This ASTER perspective was created by draping ASTER image data over topographic data from the U.S. Geological Survey National Elevation Data.

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

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

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 20.4 by 24.6 kilometers (12.6 by 15.2 miles) Location: 35.3 degrees North latitude, 111

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  10. Record of late holocene debris avalanches and lahars at Iliamna Volcano, Alaska

    USGS Publications Warehouse

    Waythomas, C.F.; Miller, T.P.; Beget, J.E.

    2000-01-01

    Iliamna Volcano is a 3053-meter high, glaciated stratovolcano in the southern Cook Inlet region of Alaska and is one of seven volcanoes in this region that have erupted multiple times during the past 10,000 yr. Prior to our studies of Iliamna Volcano, little was known about the frequency, magnitude, and character of Holocene volcanic activity. Here we present geologic evidence of the most recent eruptive activity of the volcano and provide the first outline of Late Holocene debris-avalanche and lahar formation. Iliamna has had no documented historical eruptions but our recent field investigations indicate that the volcano has erupted at least twice in the last 300 yr. Clay-rich lahar deposits dated by radiocarbon to ???1300 and ???90 yr BP are present in two major valleys that head on the volcano. These deposits indicate that at least two large, possibly deep-seated, flank failures of the volcanic edifice have occurred in the last 1300 yr. Noncohesive lahar deposits likely associated with explosive pyroclastic eruptions date to 2400-1300,>1500,???300, and <305 yr BP. Debris-avalanche deposits from recent and historical small-volume slope failures of the hydrothermally altered volcanic edifice cover most of the major glaciers on the volcano. Although these deposits consist almost entirely of hydrothermally altered rock debris and snow and ice, none of the recently generated debris avalanches evolved to lahars. A clay-rich lahar deposit that formed <90??60 radiocarbon yr BP and entered the Johnson River Valley southeast of the volcano cannot be confidently related to an eruption of Iliamna Volcano, which has had no known historical eruptions. This deposit may record an unheralded debris avalanche and lahar. ?? 2000 Elsevier Science B.V. All rights reserved.

  11. Volcano plumbing system geometry: The result of multi-parametric effects

    NASA Astrophysics Data System (ADS)

    Tibaldi, Alessandro

    2014-05-01

    Magma is transported from magma chambers towards the surface through networks of planar structures (intrusive sheets) spanning from vertical dikes to inclined sheets and horizontal sills. This study presents an overview of intrusive sheets at several volcanoes located in different settings in order to contribute to assess the factors controlling the geometry of magma plumbing systems. Data have been mainly acquired in the field and secondarily through a collection and analysis of geophysical publications; data include local lithology and tectonics of the substratum surrounding the volcano with special reference to local fault kinematics and related stress tensor, regional tectonics (general kinematics and far-field stress tensors), crustal thickness, geology and shape of the volcano, topographic setting, and characteristics of the plumbing system. Data from active volcanoes and eroded extinct volcanoes are discussed; the shallow plumbing system of active volcanoes has been reconstructed by combining available geophysical data with field information derived from outcropping sheets, morphometric analyses of pyroclastic cones, and the orientation and location of eruptive fissures. The study of eroded volcanoes enabled to assess the plumbing system geometry at lower levels in the core of the edifice or under the volcano-substratum interface. Key sites are presented in extensional, transcurrent and contractional tectonic settings, and different geodynamic areas have been investigated in North and South-America, Iceland, Southern Tyrrhenian Sea and Africa. The types of sheet arrangements that are illustrated include swarms of parallel dikes, diverging rift patterns, centrally-inclined sheets, radial dikes, bi-modal dike strikes, circum-lateral collapse sheets, and mixed members. This review shows that intrusive sheet emplacement at a volcano depends upon the combination of several local and regional factors, some of which are difficult to be constrained. While much

  12. Bulk rock composition and geochemistry of olivine-hosted melt inclusions in the Grey Porri Tuff and selected lavas of the Monte dei Porri volcano, Salina, Aeolian Islands, southern Italy

    USGS Publications Warehouse

    Doherty, Angela L.; Bodnar, Robert J.; De Vivo, Benedetto; Bohrson, Wendy A.; Belkin, Harvey E.; Messina, Antonia; Tracy, Robert J.

    2012-01-01

    The Aeolian Islands are an arcuate chain of submarine seamounts and volcanic islands, lying just north of Sicily in southern Italy. The second largest of the islands, Salina, exhibits a wide range of compositional variation in its erupted products, from basaltic lavas to rhyolitic pumice. The Monte dei Porri eruptions occurred between 60 ka and 30 ka, following a period of approximately 60,000 years of repose. The bulk rock composition of the Monte dei Porri products range from basaltic-andesite scoria to andesitic pumice in the Grey Porri Tuff (GPT), with the Monte dei Porri lavas having basaltic-andesite compositions. The typical mineral assemblage of the GPT is calcic plagioclase, clinopyroxene (augite), olivine (Fo72−84) and orthopyroxene (enstatite) ± amphibole and Ti-Fe oxides. The lava units show a similar mineral assemblage, but contain lower Fo olivines (Fo57−78). The lava units also contain numerous glomerocrysts, including an unusual variety that contains quartz, K-feldspar and mica. Melt inclusions (MI) are ubiquitous in all mineral phases from all units of the Monte dei Porri eruptions; however, only data from olivine-hosted MI in the GPT are reported here. Compositions of MI in the GPT are typically basaltic (average SiO2 of 49.8 wt %) in the pumices and basaltic-andesite (average SiO2 of 55.6 wt %) in the scoriae and show a bimodal distribution in most compositional discrimination plots. The compositions of most of the MI in the scoriae overlap with bulk rock compositions of the lavas. Petrological and geochemical evidence suggest that mixing of one or more magmas and/or crustal assimilation played a role in the evolution of the Monte dei Porri magmatic system, especially the GPT. Analyses of the more evolved mineral phases are required to better constrain the evolution of the magma.

  13. Sand Volcano Following Earthquake

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Sand boil or sand volcano measuring 2 m (6.6 ft.) in length erupted in median of Interstate Highway 80 west of the Bay Bridge toll plaza when ground shaking transformed loose water-saturated deposit of subsurface sand into a sand-water slurry (liquefaction) in the October 17, 1989, Loma Prieta earthquake. Vented sand contains marine-shell fragments. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: J.C. Tinsley, U.S. Geological Survey)

  14. Evidence for dike emplacement beneath Iliamna Volcano, Alaska in 1996

    USGS Publications Warehouse

    Roman, D.C.; Power, J.A.; Moran, S.C.; Cashman, K.V.; Doukas, M.P.; Neal, C.A.; Gerlach, T.M.

    2004-01-01

    Two earthquake swarms, comprising 88 and 2833 locatable events, occurred beneath Iliamna Volcano, Alaska, in May and August of 1996. Swarm earthquakes ranged in magnitude from -0.9 to 3.3. Increases in SO2 and CO2 emissions detected during the fall of 1996 were coincident with the second swarm. No other physical changes were observed in or around the volcano during this time period. No eruption occurred, and seismicity and measured gas emissions have remained at background levels since mid-1997. Earthquake hypocenters recorded during the swarms form a cluster in a previously aseismic volume of crust located to the south of Iliamna's summit at a depth of -1 to 4 km below sea level. This cluster is elongated to the NNW-SSE, parallel to the trend of the summit and southern vents at Iliamna and to the regional axis of maximum compressive stress determined through inversion of fault-plane solutions for regional earthquakes. Fault-plane solutions calculated for 24 swarm earthquakes located at the top of the new cluster suggest a heterogeneous stress field acting during the second swarm, characterized by normal faulting and strike-slip faulting with p-axes parallel to the axis of regional maximum compressive stress. The increase in earthquake rates, the appearance of a new seismic volume, and the elevated gas emissions at Iliamna Volcano indicate that new magma intruded beneath the volcano in 1996. The elongation of the 1996-1997 earthquake cluster parallel to the direction of regional maximum compressive stress and the accelerated occurrence of both normal and strike-slip faulting in a small volume of crust at the top of the new seismic volume may be explained by the emplacement and inflation of a subvertical planar dike beneath the summit of Iliamna and its southern satellite vents. ?? 2003 Elsevier B.V. All rights reserved.

  15. Seismic Structure of Villarrica Volcano obtained through Local Tomography

    NASA Astrophysics Data System (ADS)

    Mora-Stock, Cindy; Thorwart, Martin; Rabbel, Wolfgang

    2016-04-01

    We present a first model of the inner structure of the Villarrica volcano (Southern Chile) derived from P-wave arrival time inversion from local volcano tectonic (VT) events. A total set of 75 DSS-Cube stations was installed at the volcano surroundings between March 1st and 14th, 2012, with 50 of them at the crater, flanks and around the volcano. Volcano tectonic earthquakes located inside the network describe a NS-trending structure between 2 and 7 km below sea level at a transition zone between low and high P-wave velocity zones. The location and trend of the volume is consistent with a branch of the Liquiñe - Ofqui Fault Zone, a long lived arc-parallel 1000 km long strike-slip fault at the Chilean subduction zone. Values for P-wave velocity (Vp) averaged 4.5 km/s, and Vp/Vs ratios gave values of 1.6 to 1.7. The maximum variation of Vp is of the order of ±20%. Checkerboard test and Bootstrap method were applied. Bootstrap method shows that the standard deviation of the tomographic solutions is of the order of ±9%. Resolution given by Checkerboard test is of the order of 2-3 km. We observed three low velocity zones (LVZs) located between 1 and 5 km depth that can be associated with magma and/or other fluids. One main LVZ at 1-2 km towards NNW from the locus of seismicity; and two conduit-like LVZ s reaching from the locus of seismicity towards the surface features of the Los Nevados and Challupén pyroclastic flows (ENE and S of the crater, respectively). These two LVZs are thought to be remnant conduits of these previous eruptions. High velocity zones are observed to the east and below the crater, and can be interpreted as consolidated crustal rocks and volcanic products from previously collapsed caldera.

  16. Mud Volcanoes Formation And Occurrence

    NASA Astrophysics Data System (ADS)

    Guliyev, I. S.

    2007-12-01

    Mud volcanoes are natural phenomena, which occur throughout the globe. They are found at a greater or lesser scale in Azerbaijan, Turkmenistan, Georgia, on the Kerch and Taman peninsulas, on Sakhalin Island, in West Kuban, Italy, Romania, Iran, Pakistan, India, Burma, China, Japan, Indonesia, Malaysia, New Zealand, Mexico, Colombia, Trinidad and Tobago, Venezuela and Ecuador. Mud volcanoes are most well-developed in Eastern Azerbaijan, where more than 30% of all the volcanoes in the world are concentrated. More than 300 mud volcanoes have already been recognized here onshore or offshore, 220 of which lie within an area of 16,000 km2. Many of these mud volcanoes are particularly large (up to 400 m high). The volcanoes of the South Caspian form permanent or temporary islands, and numerous submarine banks. Many hypotheses have been developed regarding the origin of mud volcanoes. Some of those hypotheses will be examined in the present paper. Model of spontaneous excitation-decompaction (proposed by Ivanov and Guliev, 1988, 2002). It is supposed that one of major factors of the movement of sedimentary masses and formation of hydrocarbon deposits are phase transitions in sedimentary basin. At phase transitions there are abnormal changes of physical and chemical parameters of rocks. Abnormal (high and negative) pressure takes place. This process is called as excitation of the underground environment with periodicity from several tens to several hundreds, or thousand years. The relationship between mud volcanism and the generation of hydrocarbons, particularly methane, is considered to be a critical factor in mud volcano formation. At high flow rates the gas and sediment develops into a pseudo-liquid state and as flow increases the mass reaches the "so-called hover velocity" where mass transport begins. The mass of fluid moves as a quasi-uniform viscous mass through the sediment pile in a piston like manner until expelled from the surface as a "catastrophic eruption

  17. Lifespans of Cascade Arc volcanoes

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.

    2015-12-01

    Compiled argon ages reveal inception, eruptive episodes, ages, and durations of Cascade stratovolcanoes and their ancestral predecessors. Geologic mapping and geochronology show that most Cascade volcanoes grew episodically on multiple scales with periods of elevated behavior lasting hundreds of years to ca. 100 kyr. Notable examples include the paleomag-constrained, few-hundred-year-long building of the entire 15-20 km3 Shastina edifice at Mt. Shasta, the 100 kyr-long episode that produced half of Mt. Rainier's output, and the 30 kyr-long episode responsible for all of South and Middle Sister. Despite significant differences in timing and rates of construction, total durations of active and ancestral volcanoes at discrete central-vent locations are similar. Glacier Peak, Mt. Rainier, Mt. Adams, Mt. Hood, and Mt. Mazama all have inception ages of 400-600 ka. Mt. St. Helens, Mt. Jefferson, Newberry Volcano, Mt. Shasta and Lassen Domefield have more recent inception ages of 200-300 ka. Only the Sisters cluster and Mt. Baker have established eruptive histories spanning less than 50 kyr. Ancestral volcanoes centered 5-20 km from active stratocones appear to have similar total durations (200-600 kyr), but are less well exposed and dated. The underlying mechanisms governing volcano lifecycles are cryptic, presumably involving tectonic and plumbing changes and perhaps circulation cycles in the mantle wedge, but are remarkably consistent along the arc.

  18. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Eyjafjallajökull Volcano Ash Plume Particle Properties     ... satellite flew over Iceland's erupting Eyjafjallajökull volcano on April 19, 2010, its Multi-angle Imaging SpectroRadiometer (MISR) ...

  19. Earthquakes & Volcanoes, Volume 23, Number 6, 1992

    USGS Publications Warehouse

    U.S. Geological Survey; Gordon, David W., (Edited By)

    1993-01-01

    Earthquakes and Volcanoes is published bimonthly by the U.S. Geological Survey to provide current information on earthquakes and seismology, volcanoes, and related natural hazards of interest to both generalized and specialized readers.

  20. Eruptive and Geomorphic Processes at Lathrop Wells Scoria Cone Volcano

    NASA Astrophysics Data System (ADS)

    Krier, D. J.; Valentine, G. A.; Perry, F. V.; Heiken, G.

    2006-12-01

    The ~80 ka Lathrop Wells volcano (southern Nevada, U.S.A.) preserves evidence for a range of explosive processes and emplacement mechanisms of pyroclastic deposits and lava fields in a small-volume basaltic center. Early cone building by Strombolian bursts was accompanied by development of a fan-like lava field reaching ~800 m distance from the cone, built upon a gently sloping surface. Lava flows carried rafts of cone deposits, which provide indirect evidence for cone facies in lieu of direct exposures in the active quarry. Subsequent activity was of a violent Strombolian nature, with many episodes of sustained eruption columns up to a few km in height. These deposited layers of scoria lapilli and ash in different directions depending upon wind direction at the time of a given episode, reaching up to ~20 km from the vent, and also produced the bulk of the scoria cone. Lava effusion migrated from south to north around the eastern base of the cone as accumulation of lavas successively reversed the topography at the base of the cone. Late lavas were emplaced during violent Strombolian activity and continued for some time after explosive eruptions had waned. Volumes of the eruptive products are: fallout - 0.07 km3, scoria cone - 0.02 km3, and lavas - 0.03 km3. Shallow-derived xenolith concentrations suggest an upper bound on average conduit diameter of ~21 m in the uppermost 335 m beneath the volcano. The volcano was constructed over a period of at least seven months with cone building occurring only during part of that time, based upon analogy with historical eruptions. Post-eruptive geomorphic evolution varied for the three main surface types that were produced by volcanic activity: (1) scoria cone, (2) low relief surfaces (including lavas) with abundant pyroclastic material, and (3) lavas with little pyroclastic material. The role of these different initial textures must be accounted for in estimating relative ages of volcanic surfaces, and failure to account for

  1. Unzen Volcano, Japan

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This is a space radar image of the area around the Unzen volcano, on the west coast of Kyushu Island in southwestern Japan. Unzen, which appears in this image as a large triangular peak with a white flank near the center of the peninsula, has been continuously active since a series of powerful eruptions began in 1991. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 93rd orbit on April 15, 1994. The image shows an area 41.5 kilometers by 32.8 kilometers (25.7 miles by 20.3 miles) that is centered at 32.75 degrees north latitude and 130.15 degrees east longitude. North is toward the upper left of the image. The radar illumination is from the top of the image. The colors in this image were obtained using the following radar channels: red represents the L-band (vertically transmitted and received); green represents the average of L-band and C-band (vertically transmitted and received); blue represents the C-band (vertically transmitted and received). Unzen is one of 15 'Decade' volcanoes identified by the scientific community as posing significant potential threats to large local populations. The city of Shimabara sits along the coast at the foot of Unzen on its east and northeast sides. At the summit of Unzen a dome of thick lava has been growing continuously since 1991. Collapses of the sides of this dome have generated deadly avalanches of hot gas and rock known as pyroclastic flows. Volcanologists can use radar image data to monitor the growth of lava domes, to better understand and predict potentially hazardous collapses.

    Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The

  2. Volcanoes and global catastrophes

    NASA Technical Reports Server (NTRS)

    Simkin, Tom

    1988-01-01

    The search for a single explanation for global mass extinctions has let to polarization and the controversies that are often fueled by widespread media attention. The historic record shows a roughly linear log-log relation between the frequency of explosive volcanic eruptions and the volume of their products. Eruptions such as Mt. St. Helens 1980 produce on the order of 1 cu km of tephra, destroying life over areas in the 10 to 100 sq km range, and take place, on the average, once or twice a decade. Eruptions producing 10 cu km take place several times a century and, like Krakatau 1883, destroy life over 100 to 1000 sq km areas while producing clear global atmospheric effects. Eruptions producting 10,000 cu km are known from the Quaternary record, and extrapolation from the historic record suggests that they occur perhaps once in 20,000 years, but none has occurred in historic time and little is known of their biologic effects. Even larger eruptions must also exist in the geologic record, but documentation of their volume becomes increasingly difficult as their age increases. The conclusion is inescapable that prehistoric eruptions have produced catastrophes on a global scale: only the magnitude of the associated mortality is in question. Differentiation of large magma chambers is on a time scale of thousands to millions of years, and explosive volcanoes are clearly concentrated in narrow belts near converging plate margins. Volcanism cannot be dismissed as a producer of global catastrophes. Its role in major extinctions is likely to be at least contributory and may well be large. More attention should be paid to global effects of the many huge eruptions in the geologic record that dwarf those known in historic time.

  3. Global Volcano Model

    NASA Astrophysics Data System (ADS)

    Sparks, R. S. J.; Loughlin, S. C.; Cottrell, E.; Valentine, G.; Newhall, C.; Jolly, G.; Papale, P.; Takarada, S.; Crosweller, S.; Nayembil, M.; Arora, B.; Lowndes, J.; Connor, C.; Eichelberger, J.; Nadim, F.; Smolka, A.; Michel, G.; Muir-Wood, R.; Horwell, C.

    2012-04-01

    Over 600 million people live close enough to active volcanoes to be affected when they erupt. Volcanic eruptions cause loss of life, significant economic losses and severe disruption to people's lives, as highlighted by the recent eruption of Mount Merapi in Indonesia. The eruption of Eyjafjallajökull, Iceland in 2010 illustrated the potential of even small eruptions to have major impact on the modern world through disruption of complex critical infrastructure and business. The effects in the developing world on economic growth and development can be severe. There is evidence that large eruptions can cause a change in the earth's climate for several years afterwards. Aside from meteor impact and possibly an extreme solar event, very large magnitude explosive volcanic eruptions may be the only natural hazard that could cause a global catastrophe. GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. We are designing and developing an integrated database system of volcanic hazards, vulnerability and exposure with internationally agreed metadata standards. GVM will establish methodologies for analysis of the data (eg vulnerability indices) to inform risk assessment, develop complementary hazards models and create relevant hazards and risk assessment tools. GVM will develop the capability to anticipate future volcanism and its consequences. NERC is funding the start-up of this initiative for three years from November 2011. GVM builds directly on the VOGRIPA project started as part of the GRIP (Global Risk Identification Programme) in 2004 under the auspices of the World Bank and UN. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM.

  4. Relative chronology of Martian volcanoes

    NASA Technical Reports Server (NTRS)

    Landheim, R.; Barlow, N. G.

    1991-01-01

    Impact cratering is one of the major geological processes that has affected the Martian surface throughout the planet's history. The frequency of craters within particular size ranges provides information about the formation ages and obliterative episodes of Martian geologic units. The Barlow chronology was extended by measuring small craters on the volcanoes and a number of standard terrain units. Inclusions of smaller craters in units previously analyzed by Barlow allowed for a more direct comparison between the size-frequency distribution data for volcanoes and established chronology. During this study, 11,486 craters were mapped and identified in the 1.5 to 8 km diameter range in selected regions of Mars. The results are summarized in this three page report and give a more precise estimate of the relative chronology of the Martian volcanoes. Also, the results of this study lend further support to the increasing evidence that volcanism has been a dominant geologic force throughout Martian history.

  5. Remote sensing of volcanos and volcanic terrains

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, Peter J.; Francis, Peter W.; Wilson, Lionel; Pieri, David C.; Self, Stephen; Rose, William I.; Wood, Charles A.

    1989-01-01

    The possibility of using remote sensing to monitor potentially dangerous volcanoes is discussed. Thermal studies of active volcanoes are considered along with using weather satellites to track eruption plumes and radar measurements to study lava flow morphology and topography. The planned use of orbiting platforms to study emissions from volcanoes and the rate of change of volcanic landforms is considered.

  6. Multiphase modelling of mud volcanoes

    NASA Astrophysics Data System (ADS)

    Colucci, Simone; de'Michieli Vitturi, Mattia; Clarke, Amanda B.

    2015-04-01

    Mud volcanism is a worldwide phenomenon, classically considered as the surface expression of piercement structures rooted in deep-seated over-pressured sediments in compressional tectonic settings. The release of fluids at mud volcanoes during repeated explosive episodes has been documented at numerous sites and the outflows resemble the eruption of basaltic magma. As magma, the material erupted from a mud volcano becomes more fluid and degasses while rising and decompressing. The release of those gases from mud volcanism is estimated to be a significant contributor both to fluid flux from the lithosphere to the hydrosphere, and to the atmospheric budget of some greenhouse gases, particularly methane. For these reasons, we simulated the fluid dynamics of mud volcanoes using a newly-developed compressible multiphase and multidimensional transient solver in the OpenFOAM framework, taking into account the multicomponent nature (CH4, CO2, H2O) of the fluid mixture, the gas exsolution during the ascent and the associated changes in the constitutive properties of the phases. The numerical model has been tested with conditions representative of the LUSI, a mud volcano that has been erupting since May 2006 in the densely populated Sidoarjo regency (East Java, Indonesia), forcing the evacuation of 40,000 people and destroying industry, farmland, and over 10,000 homes. The activity of LUSI mud volcano has been well documented (Vanderkluysen et al., 2014) and here we present a comparison of observed gas fluxes and mud extrusion rates with the outcomes of numerical simulations. Vanderkluysen, L.; Burton, M. R.; Clarke, A. B.; Hartnett, H. E. & Smekens, J.-F. Composition and flux of explosive gas release at LUSI mud volcano (East Java, Indonesia) Geochem. Geophys. Geosyst., Wiley-Blackwell, 2014, 15, 2932-2946

  7. Alaska volcanoes guidebook for teachers

    USGS Publications Warehouse

    Adleman, Jennifer N.

    2011-01-01

    Alaska’s volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 140 volcanoes, which have been active over the last 2 million years. About 90 of these volcanoes have been active within the last 10,000 years and more than 50 of these have been active since about 1700. The volcanoes in Alaska make up well over three-quarters of volcanoes in the United States that have erupted in the last 200 years. In fact, Alaska’s volcanoes erupt so frequently that it is almost guaranteed that an Alaskan will experience a volcanic eruption in his or her lifetime, and it is likely they will experience more than one. It is hard to imagine a better place for students to explore active volcanism and to understand volcanic hazards, phenomena, and global impacts. Previously developed teachers’ guidebooks with an emphasis on the volcanoes in Hawaii Volcanoes National Park (Mattox, 1994) and Mount Rainier National Park in the Cascade Range (Driedger and others, 2005) provide place-based resources and activities for use in other volcanic regions in the United States. Along the lines of this tradition, this guidebook serves to provide locally relevant and useful resources and activities for the exploration of numerous and truly unique volcanic landscapes in Alaska. This guidebook provides supplemental teaching materials to be used by Alaskan students who will be inspired to become educated and prepared for inevitable future volcanic activity in Alaska. The lessons and activities in this guidebook are meant to supplement and enhance existing science content already being taught in grade levels 6–12. Correlations with Alaska State Science Standards and Grade Level Expectations adopted by the Alaska State Department of Education and Early Development (2006) for grades six through eleven are listed at

  8. Volcanoes in the pre-Columbian life, legend, and archaeology of Costa Rica (Central America)

    NASA Astrophysics Data System (ADS)

    Alvarado, Guillermo E.; Soto, Gerardo J.

    2008-10-01

    Costa Rica is located geographically in the southern part of the Central American Volcanic Front, a zone where interaction between the Mesoamerican and South American cultures occurred in pre-Columbian times. Several volcanoes violently erupted during the Holocene, when the first nomadic human hunters and later settlers were present. Volcanic rocks were the most important geo-resource in making artifacts and as construction materials for pre-Columbian inhabitants. Some pottery products are believed to resemble smoking volcanoes, and the settlements around volcanoes would seem to indicate their influence on daily life. Undoubtedly, volcanic eruptions disrupted the life of early settlers, particularly in the vicinity of Arenal and Irazú volcanoes, where archaeological remains show transient effects and displacement caused by periodical eruptions, but later resilient occupations around the volcanoes. Most native languages are extinct, with the exception of those presently spoken in areas far away from active volcanoes, where no words are related to volcanic phenomena or structures. The preserved legends are ambiguous, suggesting that they were either produced during the early Spanish conquest or were altered following the pre-Columbian period.

  9. Laboratory volcano geodesy

    NASA Astrophysics Data System (ADS)

    Færøvik Johannessen, Rikke; Galland, Olivier; Mair, Karen

    2014-05-01

    intrusion can be excavated and photographed from several angles to compute its 3D shape with the same photogrammetry method. Then, the surface deformation pattern can be directly compared with the shape of underlying intrusion. This quantitative dataset is essential to quantitatively test and validate classical volcano geodetic models.

  10. Io Volcano Observer (IVO)

    NASA Astrophysics Data System (ADS)

    McEwen, A. S.; Keszthelyi, L.; Spencer, J.; Thomas, N.; Johnson, T.; Christensen, P.; Wurz, P.; Glassmeier, K. H.; Shinohara, C.; Girard, T.

    2009-04-01

    In early FY2008, NASA solicited study concepts for Discovery/Scout-class missions that would be enabled by use of 2 Advanced Stirling Radioisotope Generators (ASRGs). We proposed an Io Volcano Observer (IVO) study concept, because the ASRGs enable pointing flexibility and a high data rate from a low-cost mission in Jupiter orbit. Io presents a rich array of inter-connected orbital, geophysical, atmospheric, and plasma phenomena and is the only place in the Solar System (including Earth) where we can watch very large-scale silicate volcanic processes in action. Io is the best place to study tidal heating, which greatly expands the habitable zones of planetary systems. The coupled orbital-tidal evolution of Io and Europa is key to understanding the histories of both worlds. IVO utilizes an elliptical orbit inclined > 45° to Jupiter's orbital plane with repeated fast flybys of Io. Io will have nearly constant illumination at each flyby, which facilitates monitoring of changes over time. The view of Io on approach and departure will be nearly polar, enabling unique measurement and monitoring of polar heat flow (key to tidal heating models), equatorial plumes, and magnetospheric interactions. We expect to collect and return 20 Gbits per flyby via 34-m DSN stations, >1000 times the Io data return of Galileo. The minimal payload we considered included (1) a narrow-angle camera, (2) a thermal mapper, (3) an ion and neutral mass spectrometer, and (4) a pair of fluxgate magnetometers. The camera will acquire global km-scale monitoring and sampling down to 10 m/pixel or better. One key objective is to acquire nearly simultaneous (<0.1 s) multispectral measurements to determine the peak lava temperatures, which in turn constrains the temperature and rheology of Io's mantle and whether or not the heat flow is in equilibrium with tidal heating. The thermal mapper will be similar to THEMIS on Mars Odyssey, but with bandpasses designed to monitor volcanic activity, measure heat

  11. The duration, magnitude, and frequency of subaerial volcano deformation events: New InSAR results from Latin America and a global synthesis

    NASA Astrophysics Data System (ADS)

    Pritchard, M. E.; Fournier, T.; Riddick, S.; Jay, J.; Henderson, S. T.

    2009-12-01

    We combine new observations of volcano deformation in Latin America with more than 100 previous deformation studies in other areas of the world to constrain the frequency, magnitude, and duration of subaerial volcano deformation events. We discuss implications for eruptive hazards from a given deformation event and the optimum repeat interval for proposed InSAR satellite missions. We use L-band (23.6 cm wavelength) satellite-based interferometric synthetic aperture radar (InSAR) to make the first systematic search for deformation in all volcanic arcs of Latin America (including Mexico, Central America, the Caribbean, and the northern and southern Andes), spanning 2006-2008. We combine L- and C-band (5.6 cm wavelength) InSAR observations over the southern Andes volcanoes to extend the time series from 2002-2008 and assess the capabilities of the different radars -- L-band gives superior results in highly vegetated areas. Our observations reveal 11 areas of volcano deformation, some of them in areas that were thought to be dormant. There is a lack of deformation at several erupting volcanoes, probably due to temporal aliasing. The total number of deforming volcanoes in the central and southern Andes now totals 15, comparable to the Alaska/Aleutian arc. Globally, volcanoes deform across a variety of timescales (from seconds to centuries) often without eruption, and with no apparent critical observation timescale, although observations made every minute are sometimes necessary to see precursors to eruption.

  12. Duration, magnitude, and frequency of subaerial volcano deformation events: New results from Latin America using InSAR and a global synthesis

    NASA Astrophysics Data System (ADS)

    Fournier, T. J.; Pritchard, M. E.; Riddick, S. N.

    2010-01-01

    We combine new observations of volcano deformation in Latin America with more than 100 previous deformation studies in other areas of the world to constrain the frequency, magnitude, and duration of subaerial volcano deformation events. We discuss implications for eruptive hazards from a given deformation event and the optimum repeat interval for proposed InSAR satellite missions. We use L band (23.6 cm wavelength) satellite-based interferometric synthetic aperture radar (InSAR) to make the first systematic search for deformation in all volcanic arcs of Latin America (including Mexico, Central America, the Caribbean, and the northern and southern Andes), spanning 2006-2008. We combine L and C band (5.6 cm wavelength) InSAR observations over the southern Andes volcanoes to extend the time series from 2002 to 2008 and assess the capabilities of the different radars: L band gives superior results in highly vegetated areas. Our observations reveal 11 areas of volcano deformation, some of them in areas that were thought to be dormant. There is a lack of observed deformation at several erupting volcanoes, probably due to temporal aliasing. The total number of deforming volcanoes in the central and southern Andes now totals 15 (from observations between 1992 and 2008), comparable to the Alaska/Aleutian arc. Globally, volcanoes deform across a variety of time scales (from seconds to centuries) often without eruption and with no apparent critical observation time scale, although observations made every minute are sometimes necessary to see precursors to eruption.

  13. Comparison of flank modification on Ascraeus and Arsia Montes volcanoes, Mars

    NASA Technical Reports Server (NTRS)

    Zimbelman, James R.

    1993-01-01

    Geologic mapping of the Tharsis Montes on Mars is in progress as part of the Mars Geologic Mapping Program of NASA. Mapping of the southern flanks of Ascraeus Mons at 1:500,000 scale was undertaken first followed by detailed mapping of Arsia Mons; mapping of Pavonis Mons will begin later this year. Results indicate that each of the Tharsis volcanoes displays unique variations on the general 'theme' of a martian shield volcano. Here we concentrate on the flank characteristics on Ascraeus Mons and Arsia Mons, the northernmost and southernmost of the Tharsis Montes, as illustrative of the most prominent trends.

  14. Three-dimensional P-wave velocity structure of Damavand Volcano, Iran

    NASA Astrophysics Data System (ADS)

    Mostafanejad, A.; Shomali, H.

    2009-04-01

    Damavand volcano is the highest peak in the Middle East ( 5670 m ). It is a large intraplate composite cone representing an accumulation of more than 400 km3 of trachyandesite lavas and pyroclastic material overlying the active fold and-thrust belt of the Alborz Mountains,the range that fringes the southern Caspian Sea. It shows fumarolic activity near the summit but no evidence of eruption in the past 1000 yr. The target region, Damavand volcano, is a Quaternary age volcano laying about 65 km northeast of Tehran metropolitan, Iran. A data set of over 1200 earthquakes recorded on a local 19 station short-period network between 1996 and 2006 provided by the Iranian Seismological Centre (ISC) is used for inversion in a well constrained and worldwide adopted code (SIMULPS). A 3-D velocity model beneath Damavand volcano has been obtained through inversion of P-wave arrivals of local earthquakes. About 1200 seismic events distributed around this volcano from surface up to a depth of about 30 km have been used to infer the P-wave velocity structure. The seismic arrival times were directly inverted using a 1D velocity model optimally representing the background structure. We used different grid spacing that provided detailed images of the volcano in order to investigate whether or not the anomalies are resolved by the data or are artifacts of the inversion. The resolution analysis carefully performed on the model parameters allowed the determination of a more reliable final model that represented the best results for the velocity structure beneath the volcano. The final model revealed an anomalous structure with a high velocity anomaly located beneath the volcano and a low velocity anomaly dominated the shallower depths. The spatial pattern of 3D velocity anomalies resolved in the region appears to be correlated at surface with the distribution of seismicity and major tectonic units and faults.

  15. Reconstructing the birth, life and death of ancient monogenetic basalt volcanoes using seismic reflection data

    NASA Astrophysics Data System (ADS)

    Magee, C.; Jackson, C. A. L.; Hunt-Stewart, E.

    2014-12-01

    Temporal and spatial changes in monogenetic volcano morphology and internal architecture can determine eruption style and location. However, the relationships between the external and internal characteristics of volcanoes, and sub-volcanic intrusions, are often difficult to observe at outcrop or interpret uniquely from geophysical and geodetic data. This compromises our understanding of the birth, life and death of monogenetic basalt volcanoes. To address this, we use high-quality 2D seismic reflection data from the Ceduna Sub-basin, offshore southern Australia, to quantitatively analyse 46, pristinely-preserved, Eocene-age volcanoes and a genetically-related network of sub-volcanic sills and laccoliths. Detailed seismic mapping has allowed the 3D geometry of each volcano to be reconstructed and distinct seismic facies within them to be recognised. The volcanoes have average flank dips of <10.3°, basal diameters of 1.94-18.89 km, central summits that are 0.02-1 km above the contemporaneous palaeosurface, and volumes that range from 0.06-57.21 km3. Parallel, outward-dipping seismic reflections within the shield volcanoes are interpreted to represent interbedded volcanic and clastic material, suggesting that a series of temporally separate eruptions emanated from a central vent. The shield volcanoes typically overlie the lateral tips of sills and we suggest that the intermittent eruption phases correspond to the incremental emplacement of discrete magma pulses within the laterally extensive sill-complex. This work highlights that deformation patterns preceding volcanic eruptions may: (i) be offset from the eruption site; and (ii) attributed to intrusions with complex morphologies.

  16. Structure of volcano plumbing systems: A review of multi-parametric effects

    NASA Astrophysics Data System (ADS)

    Tibaldi, Alessandro

    2015-06-01

    Magma is transported and stored in the crust mostly through networks of planar structures (intrusive sheets), ranging from vertical dykes to inclined sheets and horizontal sills, and magma chambers, which make up the plumbing system of volcanoes. This study presents an overview of plumbing systems imaged at different depths and geodynamic settings, in order to contribute to assessing the factors that control their geometry. Data were derived from personal field surveys and through the analysis of publications; observations include local lithology and tectonics of the host rock with special reference to local fault kinematics and related stress tensor, regional tectonics (general kinematics and far-field stress tensors), geology and shape of the volcano, topographic settings, and structural and petrochemical characteristics of the plumbing system. Information from active volcanoes and eroded extinct volcanoes is discussed; the shallow plumbing system of active volcanoes has been reconstructed by combining available geophysical data with field information derived from outcropping sheets, morphometric analyses of pyroclastic cones, and the orientation and location of eruptive fissures. The study of eroded volcanoes enabled to assess the plumbing system geometry at deeper levels in the core of the edifice or underneath the volcano-substratum interface. Key sites are presented in extensional, transcurrent and contractional tectonic settings from North and South-America, Iceland, the Southern Tyrrhenian Sea and Africa. The types of sheet arrangements illustrated include swarms of parallel dykes, diverging rift patterns, centrally-inclined sheets, ring and radial dykes, circum-lateral collapse sheets, sills, and mixed members. This review shows that intrusive sheet emplacement at a volcano depends upon the combination of several local and regional factors, some of which are difficult to be constrained. While much progress has been made, it is still very challenging to

  17. What Happened to Our Volcano?

    ERIC Educational Resources Information Center

    Mangiante, Elaine Silva

    2006-01-01

    In this article, the author presents an investigative approach to "understanding Earth changes." The author states that students were familiar with earthquakes and volcanoes in other regions of the world but never considered how the land beneath their feet had experienced changes over time. Here, their geology unit helped them understand and…

  18. On the geometric form of volcanoes - Comment

    NASA Technical Reports Server (NTRS)

    Wood, C. A.

    1982-01-01

    The model of Lacey et al. (1981) accounting for the geometric regularity and approximate cone shape of volcanoes is discussed. It is pointed out that, contrary to the model, volcano eruptions do not occur randomly in elevation and azimuth, but are commonly restricted to summit vents and a few well defined flank zones, so that the form of a volcano is determined by its vent locations and styles of eruption. Other false predictions of the model include the constancy of lava volumes at all vent elevations, the increase in volcano radius as the square root of time, a critical height for volcano growth, the influence of planetary gravity on volcano height and the negligible influence of ash falls and flows and erosional deposition. It is noted that the model of Shteynberg and Solov'yev, in which cone shape is related to stresses due to increasing cone height, may provide a better understanding of volcano morphology.

  19. Iridium emissions from Hawaiian volcanoes

    NASA Technical Reports Server (NTRS)

    Finnegan, D. L.; Zoller, W. H.; Miller, T. M.

    1988-01-01

    Particle and gas samples were collected at Mauna Loa volcano during and after its eruption in March and April, 1984 and at Kilauea volcano in 1983, 1984, and 1985 during various phases of its ongoing activity. In the last two Kilauea sampling missions, samples were collected during eruptive activity. The samples were collected using a filterpack system consisting of a Teflon particle filter followed by a series of 4 base-treated Whatman filters. The samples were analyzed by INAA for over 40 elements. As previously reported in the literature, Ir was first detected on particle filters at the Mauna Loa Observatory and later from non-erupting high temperature vents at Kilauea. Since that time Ir was found in samples collected at Kilauea and Mauna Loa during fountaining activity as well as after eruptive activity. Enrichment factors for Ir in the volcanic fumes range from 10,000 to 100,000 relative to BHVO. Charcoal impregnated filters following a particle filter were collected to see if a significant amount of the Ir was in the gas phase during sample collection. Iridium was found on charcoal filters collected close to the vent, no Ir was found on the charcoal filters. This indicates that all of the Ir is in particulate form very soon after its release. Ratios of Ir to F and Cl were calculated for the samples from Mauna Loa and Kilauea collected during fountaining activity. The implications for the KT Ir anomaly are still unclear though as Ir was not found at volcanoes other than those at Hawaii. Further investigations are needed at other volcanoes to ascertain if basaltic volcanoes other than hot spots have Ir enrichments in their fumes.

  20. Volcano deformation in central Main Ethiopian Rift system (Aluto Volcano) inferred from continuous GPS and dynamic gravity observations

    NASA Astrophysics Data System (ADS)

    Birhanu, Yelebe; Biggs, Juliet; Gottsmann, Joachim; Lewi, Elias; Lloyd, Ryan; Bekele, Berhanu

    2016-04-01

    Silicic volcanic centres in the rift systems frequently experience unrest indicating long-term activity in the underlying magmatic system, but it is difficult to distinguish the contributions of hydrothermal fluids, magma or gasses. Aluto volcano which is located in the central MER system is situated between the Lakes Ziway and Langano in the north and south respectively. Continuous GPS installed from April 2013 to October 2015 shows subsidence initially, with the largest subsidence observed in the eastern part of the caldera (2 cm/yr). InSAR observations from TerraSAR-X show a radially-symmetric pattern of long-term subsidence. Dynamic gravity surveys carried out in October 2014 and 2015 showed that there is a net mass loss in the western and central part of the caldera and mass gain in the eastern and southern part of the caldera, with a sharp gradient between the two. This complex spatial pattern of gravity change is significantly different to the simple pattern of deformation indicating multiple sources of pressure and mass change exist within the caldera. We explain the ratio of gravity to height change (dg/dh) throughout the volcano by considering cooling and crystallisation of magma body, draining and precipitation of hydrothermal fluids and changes in the water table and lake levels. Keywords: volcano deformation, dynamic gravity, continental rift

  1. Space Radar Image of Colima Volcano, Jalisco, Mexico

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image of the Colima volcano in Jalisco, Mexico, a vigorously active volcano that erupted as recently as July 1994. The eruption partially destroyed a lava dome at the summit and deposited a new layer of ash on the volcano's southern slopes. Surrounding communities face a continuing threat of ash falls and volcanic mudflows from the volcano, which has been designated one of 15 high-risk volcanoes for scientific study during the next decade. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 24th orbit on October 1, 1994. The image is centered at 19.4 degrees north latitude, 103.7 degrees west longitude. The area shown is approximately 35.7 kilometers by 37.5 kilometers (22 miles by 23 miles). This single-frequency, multi-polarized SIR-C image shows: red as L-band horizontally transmitted and received; green as L-band horizontally transmitted and vertically received; and blue as the ratio of the two channels. The summit area appears orange and the recent deposits fill the valleys along the south and southwest slopes. Observations from space are helping scientists understand the behavior of dangerous volcanoes and will be used to mitigate the effects of future eruptions on surrounding populations. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: the L-band (24 cm), the C-band (6 cm) and the X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature

  2. Most recent fall deposits of Ksudach Volcano, Kamchatka, Russia

    NASA Technical Reports Server (NTRS)

    Bursik, M.; Melekestsev, I. V.; Brajtseva, O. A.

    1993-01-01

    Three of four Plinian eruptions from Ksudach Volcano are among the four largest explosive eruptions in southern Kamchatka during the past 2000 years. The earliest of the eruptions was voluminous and was accompanied by an ignimbrite and the fifth and most recent Cddera collapse event at Ksudach. The isopach pattern is consistent with a column height of 23 km. The three more recent and smaller eruptions were from the Shtyubel' Cone, within the fifth caldera. Using isopach and grain size isopleth patterns, column heights ranged from >10 to 22 kin. Although the oldest eruption may have produced a large acidity peak in the Greenland ice, the three Shtyubel' events may not be related to major acid deposition. Thus it is possible that few if any of the uncorrelated acidity peaks of the past 2000 years in Greenland ice cores result from eruptions in southern Kamchatka.

  3. Interdisciplinary studies of eruption at Chaitén volcano, Chile

    USGS Publications Warehouse

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

    2010-01-01

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

  4. Interdisciplinary Studies of Eruption at Chaitén Volcano, Chile

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  5. Volcano-tectonic structures and CO2-degassing patterns in the Laacher See basin, Germany

    NASA Astrophysics Data System (ADS)

    Goepel, Andreas; Lonschinski, Martin; Viereck, Lothar; Büchel, Georg; Kukowski, Nina

    2015-07-01

    The Laacher See Volcano is the youngest (12,900 year BP) eruption center of the Quarternary East-Eifel Volcanic Field in Germany and has formed Laacher See, the largest volcanic lake in the Eifel area. New bathymetric data of Laacher See were acquired by an echo sounder system and merged with topographic light detection and ranging (LiDAR) data of the Laacher See Volcano area to form an integrated digital elevation model. This model provides detailed morphological information about the volcano basin and results of sediment transport therein. Morphological analysis of Laacher See Volcano indicates a steep inner crater wall (slope up to 30°) which opens to the south. The Laacher See basin is divided into a deep northern and a shallower southern part. The broader lower slopes inclined with up to 25° change to the almost flat central part (maximum water depth of 51 m) with a narrow transition zone. Erosion processes of the crater wall result in deposition of volcaniclastics as large deltas in the lake basin. A large subaqueous slide was identified at the northeastern part of the lake. CO2-degassing vents (wet mofettes) of Laacher See were identified by a single-beam echo sounder system through gas bubbles in the water column. These are more frequent in the northern part of the lake, where wet mofettes spread in a nearly circular-shaped pattern, tracing the crater rim of the northern eruption center of the Laacher See Volcano. Additionally, preferential paths for gas efflux distributed concentrically inside the crater rim are possibly related to volcano-tectonic faults. In the southern part of Laacher See, CO2 vents occur in a high spatial density only within the center of the arc-shaped structure Barschbuckel possibly tracing the conduit of a tuff ring.

  6. Alaska Volcano Observatory's KML Tools

    NASA Astrophysics Data System (ADS)

    Valcic, L.; Webley, P. W.; Bailey, J. E.; Dehn, J.

    2008-12-01

    Virtual Globes are now giving the scientific community a new medium to present data, which is compatible across multiple disciplines. They also provide scientists the ability to display their data in real-time, a critical factor in hazard assessment. The Alaska Volcano Observatory remote sensing group has developed Keyhole Markup Language (KML) tools that are used to display satellite data for volcano monitoring and forecast ash cloud movement. The KML tools allow an analyst to view the satellite data in a user-friendly web based environment, without a reliance on non-transportable, proprietary software packages. Here, we show how the tools are used operationally for thermal monitoring of volcanic activity, volcanic ash cloud detection and dispersion modeling, using the Puff model. animate.images.alaska.edu/

  7. Venus - Volcano With Massive Landslides

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This Magellan full-resolution mosaic which covers an area 143 by 146 kilometers (89 by 91 miles) is centered at 55 degrees north latitude, 266 degrees east longitude. The bright feature, slightly south of center is interpreted to be a volcano, 15-20 kilometers (9.3 to 12.4 miles) in diameter with a large apron of blocky debris to its right and some smaller aprons to its left. A preferred explanation is that several massive catastrophic landslides dropped down steep slopes and were carried by their momentum out into the smooth, dark lava plains. At the base of the east-facing or largest scallop on the volcano is what appears to be a large block of coherent rock, 8 to 10 kilometers (5 to 6 miles) in length. The similar margin of both the scallop and block and the shape in general is typical of terrestrial slumped blocks (masses of rock which slide and rotate down a slope instead of breaking apart and tumbling). The bright lobe to the south of the volcano may either be a lava flow or finer debris from other landslides. This volcanic feature, characterized by its scalloped flanks is part of a class of volcanoes called scalloped or collapsed domes of which there are more than 80 on Venus. Based on the chute-like shapes of the scallops and the existence of a spectrum of intermediate to well defined examples, it is hypothesized that all of the scallops are remnants of landslides even though the landslide debris is often not visible. Possible explanations for the missing debris are that it may have been covered by lava flows, the debris may have weathered or that the radar may not be recognizing it because the individual blocks are too small

  8. New studies of Martian volcanoes

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, P. J.; Robinson, M. S.; Zisk, S. H.

    1991-01-01

    To investigate the morphology, topography, and evolution of volcanic constructs on Mars, researchers have been studying the volcanoes Olympus Mons, Tyrrhena Patera, and Apollinaris Patera. These studies relied upon the analysis of digital Viking orbiter images to measure the depth and slopes of the summit area of Olympus Mons, upon new Earth-based radar measurements for the analysis of the slopes of Tyrrhena Patera, and upon the color characteristics of the flanks of Apollinaris Patera for information regarding surface properties.

  9. Glaciation of Haleakala volcano, Hawaii

    SciTech Connect

    Moore, J.G.; Mark, R. ); Porter, S.C. . Quaternary Research Center)

    1993-04-01

    Early debates regarding the large (5 [times] 10 km) summit crater'' of Haleakala volcano (3,055 m altitude) on the island of Maui attributed its origin to renting, rifting, caldera collapse, or erosion. It now is commonly assumed to have resulted from headward expansion of giant canyons by stream erosion (Stearns, 1942). Slope maps and shaded relief images based on new USGS digital elevation data point to the apparent overfit of the canyons that drain the summit depression. Studies of drowned coral reefs and terraces on the offshore east rift of Haleakala indicate that this part of the volcano has undergone submergence of about 2 km, as well as tilting, since 850 ka ago. Such subsidence indicates that the summit altitude at the end of the shield-building phase reached ca. 5,000 m, well above both the present and full-glacial snowlines. A comparison with the radiometrically dated glacial record of Mauna Kea and its reconstructed snowline history suggests that Haleakala experienced 10 or more glaciations, the most extensive during marine isotope stages 20, 18, and 16. By isotope stage 10, the summit had subsided below the full-glacial snowline. Diamictons on the south slope of the volcano, previously described as mudflows, contain lava clasts with superchilled margins, identical to margins of subglacially erupted lavas on Mauna Kea. Glacier ice that mantled the upper slopes of the volcano continuously for several hundred thousand years and intermittently thereafter, is inferred to have carved Haleakala crater and the upper reaches of large canyons radiating from it.

  10. Flank tectonics of Martian volcanoes

    SciTech Connect

    Thomas, P.J. ); Squyres, S.W. ); Carr, M.H. )

    1990-08-30

    On the flanks of Olympus Mons is a series of terraces, concentrically distributed around the caldera. Their morphology and location suggest that they could be thrust faults caused by compressional failure of the cone. In an attempt to understand the mechanism of faulting and the possible influences of the interior structure of Olympus Mons, the authors have constructed a numerical model for elastic stresses within a Martian volcano. In the absence of internal pressurization, the middle slopes of the cone are subjected to compressional stress, appropriate to the formation of thrust faults. These stresses for Olympus Mons are {approximately}250 MPa. If a vacant magma chamber is contained within the cone, the region of maximum compressional stress is extended toward the base of the cone. If the magma chamber is pressurized, extensional stresses occur at the summit and on the upper slopes of the cone. For a filled but unpressurized magma chamber, the observed positions of the faults agree well with the calculated region of high compressional stress. Three other volcanoes on Mars, Ascraeus Mons, Arsia Mons, and Pavonis Mons, possess similar terraces. Extending the analysis to other Martian volcanoes, they find that only these three and Olympus Mons have flank stresses that exceed the compressional failure strength of basalt, lending support to the view that the terraces on all four are thrust faults.

  11. Earthquakes - Volcanoes (Causes and Forecast)

    NASA Astrophysics Data System (ADS)

    Tsiapas, E.

    2009-04-01

    EARTHQUAKES - VOLCANOES (CAUSES AND FORECAST) ELIAS TSIAPAS RESEARCHER NEA STYRA, EVIA,GREECE TEL.0302224041057 tsiapas@hol.gr The earthquakes are caused by large quantities of liquids (e.g. H2O, H2S, SO2, ect.) moving through lithosphere and pyrosphere (MOHO discontinuity) till they meet projections (mountains negative projections or projections coming from sinking lithosphere). The liquids are moved from West Eastward carried away by the pyrosphere because of differential speed of rotation of the pyrosphere by the lithosphere. With starting point an earthquake which was noticed at an area and from statistical studies, we know when, where and what rate an earthquake may be, which earthquake is caused by the same quantity of liquids, at the next east region. The forecast of an earthquake ceases to be valid if these components meet a crack in the lithosphere (e.g. limits of lithosphere plates) or a volcano crater. In this case the liquids come out into the atmosphere by the form of gasses carrying small quantities of lava with them (volcano explosion).

  12. Record completeness for individual volcanoes

    NASA Astrophysics Data System (ADS)

    Bebbington, Mark

    2016-04-01

    There has been considerable recent attention paid to completeness in global and regional (e.g. Japan) eruption data bases. This has taken the form of estimating dates at which the record is complete, either at a global or regional level, at a given VEI or magnitude. This has obvious utility when estimating hazard from very large eruptions, which may have effects 1000s of km from source. However, at a more local level, the question of interest is not so much the global, or the regional, completeness level, but the completeness of the record for an individual volcano. For example, forecast hazard is critically dependent on the size of the eruption, but it is impossible even to statistically describe the size distribution without knowing the completeness of the record. Current methods for eruption catalogue completeness using extreme value statistics rely on large samples for their validity, so a new approach is required for individual volcanoes, which may have only a handful of known eruptions. We will consider one possible such approach based using a Bayesian sequential algorithm assuming that the underlying process is Poissonian and that completeness at a lower VEI implies completeness at all higher VEIs. Results for individual volcanoes are compared with regional figures and, time-permitting, implications for a statistical model of VEI discussed.

  13. 2. PARKING LOT AT JAGGAR MUSEUM, VOLCANO OBSERVATORY. VIEW OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. PARKING LOT AT JAGGAR MUSEUM, VOLCANO OBSERVATORY. VIEW OF MEDIAN. NOTE VOLCANIC STONE CURBING (EDGING) TYPICAL OF MOST PARKING AREAS; TRIANGLING AT END NOT TYPICAL. MAUNA LOA VOLCANO IN BACK. - Crater Rim Drive, Volcano, Hawaii County, HI

  14. Seismic signature of a phreatic explosion: Hydrofracturing damage at Karthala volcano, Grande Comore Island, Indian Ocean

    USGS Publications Warehouse

    Savin, C.; Grasso, J.-R.; Bachelery, P.

    2005-01-01

    Karthala volcano is a basaltic shield volcano with an active hydrothermal system that forms the southern two-thirds of the Grande Comore Island, off the east coat of Africa, northwest of Madagascar. Since the start of volcano monitoring by the local volcano observatory in 1988, the July 11th, 1991 phreatic eruption was the first volcanic event seismically recorded on this volcano, and a rare example of a monitored basaltic shield. From 1991 to 1995 the VT locations, 0.5volcanoes, during the climax of the 1991 phreatic explosion, are due to the activation of the whole hydrothermal system, as roughly sized by the distribution of VT hypocenters. The seismicity rate in 1995 was still higher than the pre-eruption seismicity rate, and disagrees with the time pattern of thermo-elastic stress readjustment induced by single magma intrusions at basaltic volcanoes. We propose that it corresponds to the still ongoing relaxation of pressure heterogeneity within the hydrothermal system as suggested by the few LP events that still occurred in 1995. ?? Springer-Verlag 2005.

  15. Remote Triggering of Microearthquakes in the Piton de la Fournaise and Changbaishan Volcanoes

    NASA Astrophysics Data System (ADS)

    Li, C.; Liu, G.; Peng, Z.; Brenguier, F.; Dufek, J.

    2015-12-01

    Large earthquakes are capable of triggering seismic, aseismic and hydrological responses at long-range distances. In particular, recent studies have shown that microearthquakes are mostly triggered in volcanic/geothermal regions. However, it is still not clear how widespread the phenomenon is, and whether there are any causal links between large earthquakes and subsequent volcanic unrest/eruptions. In this study we conduct a systematic search for remotely triggered activity at the Piton de la Fournaise (PdlF) and Changbaishan (CBS) volcanoes. The PdlF is a shield volcano located on the east-southern part of the Reunion Island in Indian Ocean. It is one of the most active volcanoes around the world. The CBS volcano is an intraplate stratovolcano on the border between China and North Korea, and it was active with a major eruption around 1100 years ago and has been since dormant from AD 1903, however, it showed signals of unrest recently. We choose these regions because they are well instrumented and spatially close to recent large earthquakes, such as the 2004/12/26 Mw9.1 Sumatra, 2011/03/11 Mw9.0 Tohoku, and the 2012/04/11 Mw8.6 Indian Ocean Earthquakes. By examining continuous waveforms a few hours before and after many earthquakes since 2000, we find many cases of remote triggering around the CBS volcano. In comparison, we only identify a few cases of remotely triggered seismicity around the PdlF volcano, including the 2004 Sumatra earthquake. Notably, the 2012 Indian Ocean earthquake and its M8.2 aftershock did not trigger any clear increase of seismicity, at least during their surface waves. Our next step is to apply a waveform matching method to automatically detect volcano-seismicity in both regions, and then use them to better understand potential interactions between large earthquakes and volcanic activities.

  16. Seismic signature of a phreatic explosion: hydrofracturing damage at Karthala volcano, Grande Comore Island, Indian Ocean

    NASA Astrophysics Data System (ADS)

    Savin, Cécile; Grasso, Jean-Robert; Bachelery, Patrick

    2005-09-01

    Karthala volcano is a basaltic shield volcano with an active hydrothermal system that forms the southern two-thirds of the Grande Comore Island, off the east coat of Africa, northwest of Madagascar. Since the start of volcano monitoring by the local volcano observatory in 1988, the July 11th, 1991 phreatic eruption was the first volcanic event seismically recorded on this volcano, and a rare example of a monitored basaltic shield. From 1991 to 1995 the VT locations, 0.5volcanoes, during the climax of the 1991 phreatic explosion, are due to the activation of the whole hydrothermal system, as roughly sized by the distribution of VT hypocenters. The seismicity rate in 1995 was still higher than the pre-eruption seismicity rate, and disagrees with the time pattern of thermo-elastic stress readjustment induced by single magma intrusions at basaltic volcanoes. We propose that it corresponds to the still ongoing relaxation of pressure heterogeneity within the hydrothermal system as suggested by the few LP events that still occurred in 1995.

  17. Thematic mapper studies of Andean volcanoes

    NASA Technical Reports Server (NTRS)

    Francis, P. W.

    1986-01-01

    The primary objective was to identify all the active volcanoes in the Andean region of Bolivia. Morphological features of the Tata Sabaya volcano, Bolivia, were studied with the thematic mapper. Details include marginal levees on lava and pyroclastic flows, and summit crater structure. Valley glacier moraine deposits, not easily identified on the multispectral band scanner, were also unambiguous, and provide useful marker horizons on large volcanic edifices which were built up in preglacial times but which were active subsequently. With such high resolution imagery, it is not only possible to identify potentially active volcanoes, but also to use standard photogeological interpretation to outline the history of individual volcanoes.

  18. Magnetic constraints on the subsurface structure of Akita-Yakeyama volcano, northeast Japan

    NASA Astrophysics Data System (ADS)

    Okuma, S.

    1998-02-01

    Magnetic analyses have been conducted in and around Akita-Yakeyama volcano at the northwestern edge of the Sengan Geothermal Area, northeast Japan to reveal the regional and local subsurface structures of the area. First, a magnetization intensity mapping method has been applied to analyze aeromagnetic anomalies of the area. Generally, magnetization highs and lows lie on volcanic rocks which are normally and reversely magnetized, respectively. Magnetization lows with small amplitudes are distributed on hydrothermally altered areas. These results imply the usefulness of the method to estimate the young volcanic activities of Quaternary volcanic areas. Detailed magnetic modeling reveals the subsurface structure of Akita-Yakeyama volcano itself. Rock magnetic data from volcanic rocks, both from the surface and cores in the geothermal exploration wells, have been employed for the modeling. The resultant magnetic structure indicates the following: the surface volcanic rocks are underlain by granitic intrusions which have minimum thicknesses of about 2,000 m below the northern flank of volcano; in the southern flank, the surface volcanic rocks are underlain widely by the Old-Tamagawa Welded Tuffs which are reversely magnetized. These results show a good agreement with a geologic interpretation in and around the volcano, especially with a hypothesis of the existence of buried calderas below the present volcano.

  19. Newberry Volcano (Oregon, USA) Revised

    NASA Astrophysics Data System (ADS)

    Donnelly-Nolan, J. M.; Grove, T. L.

    2015-12-01

    Newberry Volcano (NV) located E. of the Cascades arc axis is often interpreted as (1) a High Lava Plains (NW Basin & Range -- B&R) volcano hosting rhyolites generated by a traveling plume, (2) a shield volcano built of basalt, or (3) an enigma unrelated to the adjacent High Cascades. Recent work shows that these interpretations are incorrect. Petrologic, geochemical, isotopic, drill hole, & seismic data indicate that the NV magma system results from arc-related processes at the NW corner of the B&R, where this major extensional province impinges on the Cascades arc. NV rhyolites are geochemically distinct and lower in SiO2 than those to the east where a general NW-younging trend of rhyolite ages has suggested a traveling hotspot -- a consequence instead of propagation of B&R extension. NV lies ~90 km above the downgoing slab based on seismic evidence (McCrory et al. 2012), ~15 km deeper than under the Three Sisters (TS) volcanic complex 60 km to the NW on the arc axis. NV & TS exhibit a range of compositions and both have generated rhyodacite with unusually high Na2O contents (~7 wt. %; Mandler et al. 2014), exhibiting similar petrogenetic processes. Silicic lavas and tuffs of the caldera-centric NV make up a significant component (~20% of drill core) of its 600 km3, although basaltic andesite is the dominant composition. Basalts of calcalkaline affinity erupted on the edifice as recently as early Holocene time. These basalts contain petrologic evidence for high pre-eruptive H2O contents, have strong arc-like trace element signatures, and are isotopically Cascadian and distinct from basalts to the east in the B&R that have much higher 3/4He (Graham et al. 2009). NV is one variety of Cascades arc volcano among which are a range of stratovolcanoes including Mt. Baker (15 km3) and Mt. Shasta (500 km3), a Holocene caldera (Crater Lake), and the many basaltic andesite shield volcanoes that make up most of the Oregon High Cascades.

  20. Alaska Volcano Observatory at 20

    NASA Astrophysics Data System (ADS)

    Eichelberger, J. C.

    2008-12-01

    The Alaska Volcano Observatory (AVO) was established in 1988 in the wake of the 1986 Augustine eruption through a congressional earmark. Even within the volcanological community, there was skepticism about AVO. Populations directly at risk in Alaska were small compared to Cascadia, and the logistical costs of installing and maintaining monitoring equipment were much higher. Questions were raised concerning the technical feasibility of keeping seismic stations operating through the long, dark, stormy Alaska winters. Some argued that AVO should simply cover Augustine with instruments and wait for the next eruption there, expected in the mid 90s (but delayed until 2006), rather than stretching to instrument as many volcanoes as possible. No sooner was AVO in place than Redoubt erupted and a fully loaded passenger 747 strayed into the eruption cloud between Anchorage and Fairbanks, causing a powerless glide to within a minute of impact before the pilot could restart two engines and limp into Anchorage. This event forcefully made the case that volcano hazard mitigation is not just about people and infrastructure on the ground, and is particularly important in the heavily traveled North Pacific where options for flight diversion are few. In 1996, new funding became available through an FAA earmark to aggressively extend volcano monitoring far into the Aleutian Islands with both ground-based networks and round-the-clock satellite monitoring. Beyond the Aleutians, AVO developed a monitoring partnership with Russians volcanologists at the Institute of Volcanology and Seismology in Petropavlovsk-Kamchatsky. The need to work together internationally on subduction phenomena that span borders led to formation of the Japan-Kamchatka-Alaska Subduction Processes (JKASP) consortium. JKASP meets approximately biennially in Sapporo, Petropavlovsk, and Fairbanks. In turn, these meetings and support from NSF and the Russian Academy of Sciences led to new international education and

  1. Geochemical characterization of the Nirano Mud Volcano Field

    NASA Astrophysics Data System (ADS)

    Sciarra, Alessandra; Cantucci, Barbara; Ricci, Tullio; Conventi, Marzia

    2016-04-01

    fact, Rn is around 28800 Bq/m3 (southern part), CO2 up to 5.5 %, CH4 about 6000 ppm, He and H2 are 18 ppm and 39 ppm, respectively. CO2 flux measurements show high values (up to 91 g/m2day) along a natural slope, at the central sector of the NMVF, suggesting the presence of fracturation zone. CH4 fluxes show a spotty distribution and low values (mean 65,95 mg/m2day), similar to average values measured in adjacent areas (67 mg/m2day), in the Modena province. The mud volcanoes of Nirano are characterized by mud, gas bubbles, and muddy water, which may also contain a small fraction of liquid hydrocarbons. Water analysis highlights connate origin of fluids dominated by sodium-chloride component. Extruded gas is chemically composed essentially by methane and in minor measure by nitrogen, oxygen, carbon dioxide, and ethane. Isotopic analyses highlight the thermogenic origin of emitted methane.

  2. Preparing for Routine Satellite Global Volcano Deformation Observations: The Volcano Deformation Database Task Force

    NASA Astrophysics Data System (ADS)

    Pritchard, M. E.; Jay, J.; Andrews, B. J.; Cooper, J.; Henderson, S. T.; Delgado, F.; Biggs, J.; Ebmeier, S. K.

    2014-12-01

    Satellite Interferometric Synthetic Aperture Radar (InSAR) has greatly expanded the number volcanoes that can be monitored for ground deformation - the number of known deforming volcanoes has increased almost five-fold since 1997 (to more than 213 volcanoes in 2014). However, from 1992-2014, there are still gaps in global volcano surveillance and only a fraction of the 1400 subaerial Holocene volcanoes have frequent observations in this time period. Starting in 2014, near global observations of volcano deformation should begin with the Sentinel satellites from the European Space Agency, ALOS-2 from the Japanese Space Agency, and eventually NISAR from the Indian Space Agency and NASA. With more frequent observations, more volcano deformation episodes are sure to be observed, but evaluating the significance of the observed deformation is not always straightforward -- how can we determine if deformation will lead to eruption? To answer this question, an international task force has been formed to create an inventory of volcano deformation events as part of the Global Volcano Model (http://globalvolcanomodel.org/gvm-task-forces/volcano-deformation-database/). We present the first results from our global study focusing on volcanoes that have few or no previous studies. In some cases, there is a lack of SAR data (for example, volcanoes of the South Sandwich Islands). For others, observations either show an absence of deformation or possible deformation that requires more data to be verified. An example of a deforming volcano that has few past studies is Pagan, an island in the Marianas Arc comprised of 2 stratovolcanoes within calderas. Our new InSAR measurements from both the ALOS and Envisat satellites show deformation near the 1981 May VEI 4 lava flow eruption on North Pagan at 2-3 cm/year between 2004-2010. Another example of a newly observed volcano is Karthala volcano in the Comoros. InSAR observations between 2004-2010 span four eruptions, only one of which is

  3. USGS GNSS Applications to Volcano Disaster Response and Hazard Mitigation

    NASA Astrophysics Data System (ADS)

    Lisowski, M.; McCaffrey, R.

    2015-12-01

    Volcanic unrest is often identified by increased rates of seismicity, deformation, or the release of volcanic gases. Deformation results when ascending magma accumulates in crustal reservoirs, creates new pathways to the surface, or drains from magma reservoirs to feed an eruption. This volcanic deformation is overprinted by deformation from tectonic processes. GNSS monitoring of volcanoes captures transient volcanic deformation and steady and transient tectonic deformation, and we use the TDEFNODE software to unravel these effects. We apply the technique on portions of the Cascades Volcanic arc in central Oregon and in southern Washington that include a deforming volcano. In central Oregon, the regional TDEFNODE model consists of several blocks that rotate and deform internally and a decaying inflationary volcanic pressure source to reproduce the crustal bulge centered ~5 km west of South Sister. We jointly invert 47 interferograms that cover the interval from 1992 to 2010, as well as 2001 to 2015 continuous GNSS (cGNSS) and survey-mode (sGNSS) time series from stations in and around the Three Sisters, Newberry, and Crater Lake areas. A single, smoothly-decaying ~5 km deep spherical or prolate spheroid volcanic pressure source activated around 1998 provides the best fit to the combined geodetic data. In southern Washington, GNSS displacement time-series track decaying deflation of a ~8 km deep magma reservoir that fed the 2004 to 2008 eruption of Mount St. Helens. That deformation reversed when it began to recharge after the eruption ended. Offsets from slow slip events on the Cascadia subduction zone punctuate the GNSS displacement time series, and we remove them by estimating source parameters for these events. This regional TDEFNODE model extends from Mount Rainier south to Mount Hood, and additional volcanic sources could be added if these volcanoes start deforming. Other TDEFNODE regional models are planned for northern Washington (Mount Baker and Glacier

  4. Of Rings and Volcanoes

    NASA Astrophysics Data System (ADS)

    2002-01-01

    Office National d'Etudes et de Recherches Aérospatiales (ONERA) , Laboratoire d'Astrophysique de Grenoble (LAOG) and the DESPA and DASGAL laboratories of the Observatoire de Paris in France, in collaboration with ESO. The CONICA infra-red camera was built, under an ESO contract, by the Max-Planck-Institut für Astronomie (MPIA) (Heidelberg) and the Max-Planck Institut für Extraterrestrische Physik (MPE) (Garching) in Germany, in collaboration with ESO. Saturn - Lord of the rings ESO PR Photo 04a/02 ESO PR Photo 04a/02 [Preview - JPEG: 460 x 400 pix - 54k] [Normal - JPEG: 1034 x 800 pix - 200k] Caption : PR Photo 04a/02 shows the giant planet Saturn, as observed with the VLT NAOS-CONICA Adaptive Optics instrument on December 8, 2001; the distance was 1209 million km. It is a composite of exposures in two near-infrared wavebands (H and K) and displays well the intricate, banded structure of the planetary atmosphere and the rings. Note also the dark spot at the south pole at the bottom of the image. One of the moons, Tethys, is visible as a small point of light below the planet. It was used to guide the telescope and to perform the adaptive optics "refocussing" for this observation. More details in the text. Technical information about this photo is available below. This NAOS/CONICA image of Saturn ( PR Photo 04a/02 ), the second-largest planet in the solar system, was obtained at a time when Saturn was close to summer solstice in the southern hemisphere. At this moment, the tilt of the rings was about as large as it can be, allowing the best possible view of the planet's South Pole. That area was on Saturn's night side in 1982 and could therefore not be photographed during the Voyager encounter. The dark spot close to the South Pole is a remarkable structure that measures approximately 300 km across. It was only recently observed in visible light from the ground with a telescope at the Pic du Midi Observatory in the Pyrenees (France) - this is the first infrared image to

  5. Double Glacier Volcano, a 'new' Quaternary volcano in the eastern Aleutian volcanic arc

    USGS Publications Warehouse

    Reed, B.L.; Lanphere, M.A.; Miller, T.P.

    1992-01-01

    The Double Glacier Volcano (DGV) is a small dome complex of porphyritic hornblende andesite and dacite that is part of the Cook Inlet segment of Quaternary volcanoes of the eastern Aleutian arc. Its discovery reduces the previously described large volcano gap in Cook Inlet segment to a distance similar to that between other volcanoes in the area. DGV lavas are medium-K, calcalkaline andesites and dacites with concentrations of major and minor elements similar to the other Quaternary volcanoes of the Cook Inlet segment. Available K-Ar ages indicate that DGV was active 600-900 ka. ?? 1992 Springer-Verlag.

  6. Smithsonian Volcano Data on Google Earth

    NASA Astrophysics Data System (ADS)

    Venzke, E.; Siebert, L.; Luhr, J. F.

    2006-12-01

    Interactive global satellite imagery datasets such as hosted by Google Earth provide a dynamic platform for educational outreach in the Earth Sciences. Users with widely varied backgrounds can easily view geologic features on a global-to-local scale, giving access to educational background on individual geologic features or events such as volcanoes and earthquakes. The Smithsonian Institution's Global Volcanism Program (GVP) volcano data became available as a Google Earth layer on 11 June 2006. Locations for about 1550 volcanoes with known or possible Holocene activity are shown as red triangles with associated volcano names that appear when zooming in to a regional-scale view. Clicking on a triangle opens an informational balloon that displays a photo, geographic data, and a brief paragraph summarizing the volcano's geologic history. The balloon contains links to a larger version of the photo with credits and a caption and to more detailed information on the volcano, including eruption chronologies, from the GVP website. Links to USGS and international volcano observatories or other websites focusing on regional volcanoes are also provided, giving the user ready access to a broad spectrum of volcano data. Updates to the GVP volcano layer will be provided to Google Earth. A downloadable file with the volcanoes organized regionally is also available directly from the GVP website (www.volcano.si.edu) and provides the most current volcano data set. Limitations of the implied accuracy of spacially plotted data at high zoom levels are also apparent using platforms such as Google Earth. Real and apparent mismatches between plotted locations and the summits of some volcanoes seen in Google Earth satellite imagery occur for reasons including data precision (deg/min vs. deg/min/sec) and the GVP convention of plotting the center-point of large volcanic fields, which often do not correspond to specific volcanic vents. A more fundamental problem originates from the fact that

  7. ASTER Images Mt. Usu Volcano

    NASA Technical Reports Server (NTRS)

    2000-01-01

    On April 3, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra Satellite captured this image of the erupting Mt. Usu volcano in Hokkaido, Japan. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image the Earth for the next 6 years to map and monitor the changing surface of our planet.

    This false color infrared image of Mt Usu volcano is dominated by Lake Toya, an ancient volcanic caldera. On the south shore is the active Usu volcano. On Friday, March 31, more than 11,000 people were evacuated by helicopter, truck and boat from the foot of Usu, that began erupting from the northwest flank, shooting debris and plumes of smoke streaked with blue lightning thousands of feet in the air. Although no lava gushed from the mountain, rocks and ash continued to fall after the eruption. The region was shaken by thousands of tremors before the eruption. People said they could taste grit from the ash that was spewed as high as 2,700 meters (8,850 ft) into the sky and fell to coat surrounding towns with ash. 'Mount Usu has had seven significant eruptions that we know of, and at no time has it ended quickly with only a small scale eruption,' said Yoshio Katsui, a professor at Hokkaido University. This was the seventh major eruption of Mount Usu in the past 300 years. Fifty people died when the volcano erupted in 1822, its worst known eruption.

    In the image, most of the land is covered by snow. Vegetation, appearing red in the false color composite, can be seen in the agricultural fields, and forests in the mountains. Mt. Usu is crossed by three dark streaks. These are the paths of ash deposits that rained out from eruption plumes two days earlier. The prevailing wind was from the northwest, carrying the ash away from the main city of Date. Ash deposited can be traced on the image as far away as 10 kilometers (16

  8. Geoflicks Reviewed--Films about Hawaiian Volcanoes.

    ERIC Educational Resources Information Center

    Bykerk-Kauffman, Ann

    1994-01-01

    Reviews 11 films on volcanic eruptions in the United States. Films are given a one- to five-star rating and the film's year, length, source and price are listed. Top films include "Inside Hawaiian Volcanoes" and "Kilauea: Close up of an Active Volcano." (AIM)

  9. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... 46-degree forward-viewing cameras of the Eyjafjallajökull volcano and its erupting ash plume. In addition to the main plume, there are ... is necessary to separate out wind and height (see  Volcano Plume Heights ). To view the image in 3-D, use red/blue glasses with ...

  10. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Ash from Eyjafjallajökull Volcano, Iceland Stretches over the North Atlantic   ... that occurred in late March 2010, the Eyjafjallajökull Volcano in Iceland began erupting again on April 14, 2010. The resulting ash ...

  11. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... height map   Ash from Iceland's Eyjafjallajökull volcano, viewed here in imagery from the Multi-angle Imaging SpectroRadiometer ... natural-color, nadir (vertical) view of the scene, with the volcano itself located outside the upper left corner of the image. The ash ...

  12. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... to capture a series of images of the Eyjafjallajökull volcano and its erupting ash plume. Figure 1 is a view from MISR's nadir ... The companion image, Figure 2, is a stereo anaglyph (see  Volcano Plume Heights Anaglyph ) generated from the nadir and 46-degree ...

  13. Orographic Flow over an Active Volcano

    NASA Astrophysics Data System (ADS)

    Poulidis, Alexandros-Panagiotis; Renfrew, Ian; Matthews, Adrian

    2014-05-01

    Orographic flows over and around an isolated volcano are studied through a series of numerical model experiments. The volcano top has a heated surface, so can be thought of as "active" but not erupting. A series of simulations with different atmospheric conditions and using both idealised and realistic configurations of the Weather Research and Forecast (WRF) model have been carried out. The study is based on the Soufriere Hills volcano, located on the island of Montserrat in the Caribbean. This is a dome-building volcano, leading to a sharp increase in the surface skin temperature at the top of the volcano - up to tens of degrees higher than ambient values. The majority of the simulations use an idealised topography, in order for the results to have general applicability to similar-sized volcanoes located in the tropics. The model is initialised with idealised atmospheric soundings, representative of qualitatively different atmospheric conditions from the rainy season in the tropics. The simulations reveal significant changes to the orographic flow response, depending upon the size of the temperature anomaly and the atmospheric conditions. The flow regime and characteristic features such as gravity waves, orographic clouds and orographic rainfall patterns can all be qualitatively changed by the surface heating anomaly. Orographic rainfall over the volcano can be significantly enhanced with increased temperature anomaly. The implications for the eruptive behaviour of the volcano and resulting secondary volcanic hazards will also be discussed.

  14. Volcano Flank Terraces on Mars

    NASA Astrophysics Data System (ADS)

    Byrne, P. K.; van Wyk de Vries, B.; Murray, J. B.; Troll, V. R.

    2008-12-01

    Flank terraces are bulge-like structures that occur on the slopes of at least nine large shield volcanoes on Mars, and three on Earth. Terraces have a convex-upward, convex-outward morphology, with an imbricate "fish scale" stacking pattern in plan. They occur at all elevations, are scale-invariant structures, and have similar proportions to thrust faults on Earth. Suggested mechanisms of formation include elastic self-loading, lithospheric flexure, magma chamber tumescence, flank relaxation, and shallow gravitational slumping. Terrace geometries predicted by most of these mechanisms do not agree with our observations, however. Only lithospheric flexure can fully account for terrace geometry on Mars and Earth, and so is the most likely candidate mechanism for flank terrace formation. To verify this hypothesis, we conducted scaled analogue modelling experiments, and investigated the structures formed during flexure. Cones of a sand-gypsum mix were placed upon a deep layer of silicone gel, to simulate volcanic loads upon viscoelastic Martian crust. Key parameters were varied across our experimental program. In all cases convex topographic structures developed on the cones' flanks, arranged in an imbricate, overlapping plan-view pattern. These structures closely resemble flank terraces observed on Mars, and our results provide for a basic kinematic model of terrace formation. Analogue volcanoes experienced a decrease in upper surface area whilst volume was conserved; the contractional surface strain was accommodated by outward verging, circumferentially striking thrusts. The morphology of experimental structures suggests an orientation of the principal stress axes of σ1 = radial, σ2 = concentric, and σ3 = vertical. Elsewhere (J. B. Murray et al., this volume) we detail the relationship between flank terraces and other structures such as pit craters and gräben, using Ascraeus Mons as a case study. We suggest that terraces may influence the distribution and location

  15. Shiveluch Volcano, Kamchatka Peninsula, Russia

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On the night of June 4, 2001, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) captured this thermal image of the erupting Shiveluch volcano. Located on Russia's Kamchatka Peninsula, Shiveluch rises to an altitude of 2,447 meters (8,028 feet). The active lava dome complex is seen as a bright (hot) area on the summit of the volcano. To the southwest, a second hot area is either a debris avalanche or hot ash deposit. Trailing to the west is a 25-kilometer (15-mile) ash plume, seen as a cold 'cloud' streaming from the summit. At least 60 large eruptions have occurred here during the last 10,000 years; the largest historical eruptions were in 1854 and 1964.

    Because Kamchatka is located along the major aircraft routes between North America/Europe and Asia, this area is constantly monitored for potential ash hazards to aircraft. The area is part of the 'Ring of Fire,' a string of volcanoes that encircles the Pacific Ocean.

    The lower image is the same as the upper, except it has been color-coded: red is hot, light greens to dark green are progressively colder, and gray/black are the coldest areas.

    The image is located at 56.7 degrees north latitude, 161.3 degrees east longitude.

    ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

  16. Analytical volcano deformation source models

    USGS Publications Warehouse

    Lisowski, Michael

    2007-01-01

    Primary volcanic landforms are created by the ascent and eruption of magma. The ascending magma displaces and interacts with surrounding rock and fluids as it creates new pathways, flows through cracks or conduits, vesiculates, and accumulates in underground reservoirs. The formation of new pathways and pressure changes within existing conduits and reservoirs stress and deform the surrounding rock. Eruption products load the crust. The pattern and rate of surface deformation around volcanoes reflect the tectonic and volcanic processes transmitted to the surface through the mechanical properties of the crust.

  17. Isotopic composition of gases from mud volcanoes

    SciTech Connect

    Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

    1985-09-01

    A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

  18. Costa Rica's Chain of laterally collapsed volcanoes.

    NASA Astrophysics Data System (ADS)

    Duarte, E.; Fernandez, E.

    2007-05-01

    From the NW extreme to the SW end of Costa Rica's volcanic backbone, a number of laterally collapsed volcanoes can be observed. Due to several factors, attention has been given to active volcanoes disregarding the importance of collapsed features in terms of assessing volcanic hazards for future generations around inhabited volcanoes. In several cases the typical horseshoe shape amphitheater-like depression can be easily observed. In other cases due to erosion, vegetation, topography, seismic activity or drastic weather such characteristics are not easily recognized. In the order mentioned above appear: Orosi-Cacao, Miravalles, Platanar, Congo, Von Frantzius, Cacho Negro and Turrialba volcanoes. Due to limited studies on these structures it is unknown if sector collapse occurred in one or several phases. Furthermore, in the few studied cases no evidence has been found to relate collapses to actual eruptive episodes. Detailed studies on the deposits and materials composing dome-like shapes will shed light on unsolved questions about petrological and chemical composition. Volume, form and distance traveled by deposits are part of the questions surrounding most of these collapsed volcanoes. Although most of these mentioned structures are extinct, at least Irazú volcano (active volcano) has faced partial lateral collapses recently. It did presented strombolian activity in the early 60s. Collapse scars show on the NW flank show important mass removal in historic and prehistoric times. Moreover, in 1994 a minor hydrothermal explosion provoked the weakening of a deeply altered wall that holds a crater lake (150m diameter, 2.6x106 ). A poster will depict images of the collapsed volcanoes named above with mayor descriptive characteristics. It will also focus on the importance of deeper studies to assess the collapse potential of Irazú volcano with related consequences. Finally, this initiative will invite researchers interested in such topic to join future studies in

  19. Late Holocene volcanism at Medicine Lake Volcano, northern California Cascades

    USGS Publications Warehouse

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

    2016-01-01

    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

  20. A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA

    USGS Publications Warehouse

    Poland, Michael P.; Moats, W.P.; Fink, J.H.

    2008-01-01

    We mapped the geometry of 13 silicic dikes at Summer Coon, an eroded Oligocene stratovolcano in southern Colorado, to investigate various characteristics of radial dike emplacement in composite volcanoes. Exposed dikes are up to about 7 km in length and have numerous offset segments along their upper peripheries. Surprisingly, most dikes at Summer Coon increase in thickness with distance from the center of the volcano. Magma pressure in a dike is expected to lessen away from the pressurized source region, which would encourage a blade-like dike to decrease in thickness with distance from the center of the volcano. We attribute the observed thickness pattern as evidence of a driving pressure gradient, which is caused by decreasing host rock shear modulus and horizontal stress, both due to decreasing emplacement depths beneath the sloping flanks of the volcano. Based on data from Summer Coon, we propose that radial dikes originate at depth below the summit of a host volcano and follow steeply inclined paths towards the surface. Near the interface between volcanic cone and basement, which may represent a neutral buoyancy surface or stress barrier, magma is transported subhorizontally and radially away from the center of the volcano in blade-like dikes. The dikes thicken with increasing radial distance, and offset segments and fingers form along the upper peripheries of the intrusions. Eruptions may occur anywhere along the length of the dikes, but the erupted volume will generally be greater for dike-fed eruptions far from the center of the host volcano owing to the increase in driving pressure with distance from the source. Observed eruptive volumes, vent locations, and vent-area intrusions from inferred post-glacial dike-fed eruptions at Mount Adams, Washington, USA, support the proposed model. Hazards associated with radial dike emplacement are therefore greater for longer dikes that propagate to the outer flanks of a volcano. ?? Springer-Verlag 2007.

  1. Exploring Geology on the World-Wide Web--Volcanoes and Volcanism.

    ERIC Educational Resources Information Center

    Schimmrich, Steven Henry; Gore, Pamela J. W.

    1996-01-01

    Focuses on sites on the World Wide Web that offer information about volcanoes. Web sites are classified into areas of Global Volcano Information, Volcanoes in Hawaii, Volcanoes in Alaska, Volcanoes in the Cascades, European and Icelandic Volcanoes, Extraterrestrial Volcanism, Volcanic Ash and Weather, and Volcano Resource Directories. Suggestions…

  2. Fractionation and Assimilation Processes Dominate in the Generation of Silicic Magmas from Four Kermadec Arc Volcanoes

    NASA Astrophysics Data System (ADS)

    Barker, S. J.; Wilson, C. J.; Baker, J.; Wysoczanski, R. J.; Rotella, M. D.; Millet, M.; Wright, I. C.

    2010-12-01

    Recent work has shown that silicic volcanism can be abundant in intra-oceanic subduction settings, and is often associated with large explosive caldera forming eruptions. Several major petrogenic questions arise from the generation and eruption of large silicic magma bodies in such a simple subduction setting, where continental crust is absent. We have investigated the geochemistry of pyroclasts collected from four volcanoes along the Kermadec arc; a relatively young (<2 Ma) oceanic subduction zone. Raoul, Macauley and a newly discovered volcano in the northern Kermadec arc, and Healy volcano in the southern Kermadec arc have all erupted dacite-rhyolite pumice within the last 10 kyr. Examination of whole-rock, mineral and glass major and trace element chemical data shows patterns which indicate that evolved magmas are primarily generated through crystal fractionation and not by partial melting of lower crustal lithologies, particularly amphibolite. Silicic magmas and co-eruptive mafic enclaves show sub-parallel REE patterns, and crystal zonation suggests that mafic and silicic magmas are closely related, spatially and temporally. However, distinctive crystal populations in both pumice samples and plutonic xenoliths suggest that many of the crystals did not grow in the evolved magmas, but were mixed in from other sources including gabbros and tonalites. Such open system mixing is ubiquitous in magmas from the four Kermadec volcanoes. Although crystallization is the dominant process driving melt evolution in the Kermadec volcanoes, the magmatic systems are open to contributions from both newly arriving melts and previously crystallized plutonic bodies. Such contributions occur in variable proportions between magma batches, reflected by the chemical variations observed between eruption units in subaerial sequences on Raoul Island and between clustered pumice chemical compositions in dredged samples from the submarine volcanoes.

  3. Instrumentation Recommendations for Volcano Monitoring at U.S. Volcanoes Under the National Volcano Early Warning System

    USGS Publications Warehouse

    Moran, Seth C.; Freymueller, Jeff T.; LaHusen, Richard G.; McGee, Kenneth A.; Poland, Michael P.; Power, John A.; Schmidt, David A.; Schneider, David J.; Stephens, George; Werner, Cynthia A.; White, Randall A.

    2008-01-01

    As magma moves toward the surface, it interacts with anything in its path: hydrothermal systems, cooling magma bodies from previous eruptions, and (or) the surrounding 'country rock'. Magma also undergoes significant changes in its physical properties as pressure and temperature conditions change along its path. These interactions and changes lead to a range of geophysical and geochemical phenomena. The goal of volcano monitoring is to detect and correctly interpret such phenomena in order to provide early and accurate warnings of impending eruptions. Given the well-documented hazards posed by volcanoes to both ground-based populations (for example, Blong, 1984; Scott, 1989) and aviation (for example, Neal and others, 1997; Miller and Casadevall, 2000), volcano monitoring is critical for public safety and hazard mitigation. Only with adequate monitoring systems in place can volcano observatories provide accurate and timely forecasts and alerts of possible eruptive activity. At most U.S. volcanoes, observatories traditionally have employed a two-component approach to volcano monitoring: (1) install instrumentation sufficient to detect unrest at volcanic systems likely to erupt in the not-too-distant future; and (2) once unrest is detected, install any instrumentation needed for eruption prediction and monitoring. This reactive approach is problematic, however, for two reasons. 1. At many volcanoes, rapid installation of new ground-1. based instruments is difficult or impossible. Factors that complicate rapid response include (a) eruptions that are preceded by short (hours to days) precursory sequences of geophysical and (or) geochemical activity, as occurred at Mount Redoubt (Alaska) in 1989 (24 hours), Anatahan (Mariana Islands) in 2003 (6 hours), and Mount St. Helens (Washington) in 1980 and 2004 (7 and 8 days, respectively); (b) inclement weather conditions, which may prohibit installation of new equipment for days, weeks, or even months, particularly at

  4. A global database of composite volcano morphometry

    NASA Astrophysics Data System (ADS)

    Grosse, Pablo; Euillades, Pablo A.; Euillades, Leonardo D.; van Wyk de Vries, Benjamin

    2014-01-01

    We present a global database on the subaerial morphometry of composite volcanoes. Data was extracted from the 90-m resolution Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). The 759 volcanoes included in the database are the composite (i.e., polygenetic) volcanoes listed in the Smithsonian Institution Global Volcanism Program (GVP) database that are covered by the SRTM DEM, have a constructional topography and a basal width larger than 2 km. The extent of each volcano edifice was defined using the NETVOLC algorithm, which computes outlines by minimizing a cost function based on breaks in slope around the edifices. Morphometric parameters were then calculated using the MORVOLC algorithm. The parameters characterize and quantify volcano size (basal width, summit width, height, and volume), profile shape (height/basal width and summit width/basal width ratios), plan shape (ellipticity and irregularity indexes), and slopes. In addition, 104 well-defined and relatively large summit craters/calderas were manually delineated and specific parameters were computed. Most parameters show large variation without clear separations, indicating a continuum of volcano morphologies. Large overlap between the main GVP morphologic types highlights the need for a more rigorous quantitative classification of volcano morphology. The database will be maintained and updated through a website under construction.

  5. A scale for ranking volcanoes by risk

    NASA Astrophysics Data System (ADS)

    Scandone, Roberto; Bartolini, Stefania; Martí, Joan

    2016-01-01

    We propose a simple volcanic risk coefficient (VRC) useful for comparing the degree of risk arising from different volcanoes, which may be used by civil protection agencies and volcano observatories to rapidly allocate limited resources even without a detailed knowledge of each volcano. Volcanic risk coefficient is given by the sum of the volcanic explosivity index (VEI) of the maximum expected eruption from the volcano, the logarithm of the eruption rate, and the logarithm of the population that may be affected by the maximum expected eruption. We show how to apply the method to rank the risk using as examples the volcanoes of Italy and in the Canary Islands. Moreover, we demonstrate that the maximum theoretical volcanic risk coefficient is 17 and pertains to the large caldera-forming volcanoes like Toba or Yellowstone that may affect the life of the entire planet. We develop also a simple plugin for a dedicated Quantum Geographic Information System (QGIS) software to graphically display the VRC of different volcanoes in a region.

  6. Southern Africa

    Atmospheric Science Data Center

    2013-04-16

    article title:  Southern Africa     View larger JPEG image ... These Multi-angle Imaging SpectroRadiometer (MISR) images of Africa were acquired on August 25, 2000, during Terra orbit 3655. The left ... of smoke plumes and haze. The southern tip of South Africa is at the bottom of the image, and Zambia is at the top. Distinctive ...

  7. Volcanoes

    MedlinePlus

    ... also cause earthquakes, mudflows and flash floods, rock falls and landslides, acid rain, fires, and even tsunamis. Volcanic gas and ash can damage the lungs of small infants, older adults, and people with severe respiratory illnesses. Volcanic ash can affect ...

  8. Volcanoes

    MedlinePlus

    ... Hazards Preventing Violence Pressure Washer Safety High-Pressure Water Injection Injury Trench Foot or Immersion Foot Emergency Wound Care Wound Management for Healthcare Pros Power Outages When the Power Goes Out Worker Safety ...

  9. Volcanoes

    MedlinePlus

    ... is a vent in the Earth's crust. Hot rock, steam, poisonous gases, and ash reach the Earth's ... can also cause earthquakes, mudflows and flash floods, rock falls and landslides, acid rain, fires, and even ...

  10. Volcanoes

    MedlinePlus

    ... Hazardous Materials Incidents Home Fires Household Chemical Emergencies Hurricanes Landslides & Debris Flow Nuclear Blast Nuclear Power Plants ... Hazardous Materials Incidents Home Fires Household Chemical Emergencies Hurricanes Landslides & Debris Flow Nuclear Blast Nuclear Power Plants ...

  11. Volcanoes

    MedlinePlus

    ... a Flood Worker Safety Educational Materials Floods PSAs Hurricanes Before a Hurricane Make a Plan Get Supplies Get Your Family, ... Ready Evacuate or Stay at Home After a Hurricane Make Sure Your Food and Water Are Safe ...

  12. Linking space observations to volcano observatories in Latin America: Results from the CEOS DRM Volcano Pilot

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Pritchard, M. E.; Biggs, J.; Arnold, D. W. D.; Poland, M. P.; Ebmeier, S. K.; Wauthier, C.; Wnuk, K.; Parker, A. L.; Amelug, F.; Sansosti, E.; Mothes, P. A.; Macedo, O.; Lara, L.; Zoffoli, S.; Aguilar, V.

    2015-12-01

    Within Latin American, about 315 volcanoes that have been active in the Holocene, but according to the United Nations Global Assessment of Risk 2015 report (GAR15) 202 of these volcanoes have no seismic, deformation or gas monitoring. Following the 2012 Santorini Report on satellite Earth Observation and Geohazards, the Committee on Earth Observation Satellites (CEOS) has developed a 3-year pilot project to demonstrate how satellite observations can be used to monitor large numbers of volcanoes cost-effectively, particularly in areas with scarce instrumentation and/or difficult access. The pilot aims to improve disaster risk management (DRM) by working directly with the volcano observatories that are governmentally responsible for volcano monitoring, and the project is possible thanks to data provided at no cost by international space agencies (ESA, CSA, ASI, DLR, JAXA, NASA, CNES). Here we highlight several examples of how satellite observations have been used by volcano observatories during the last 18 months to monitor volcanoes and respond to crises -- for example the 2013-2014 unrest episode at Cerro Negro/Chiles (Ecuador-Colombia border); the 2015 eruptions of Villarrica and Calbuco volcanoes, Chile; the 2013-present unrest and eruptions at Sabancaya and Ubinas volcanoes, Peru; the 2015 unrest at Guallatiri volcano, Chile; and the 2012-present rapid uplift at Cordon Caulle, Chile. Our primary tool is measurements of ground deformation made by Interferometric Synthetic Aperture Radar (InSAR) but thermal and outgassing data have been used in a few cases. InSAR data have helped to determine the alert level at these volcanoes, served as an independent check on ground sensors, guided the deployment of ground instruments, and aided situational awareness. We will describe several lessons learned about the type of data products and information that are most needed by the volcano observatories in different countries.

  13. Volcanoes can muddle the greenhouse

    SciTech Connect

    Kerr, R.A.

    1990-01-01

    As scientists and politicians anxiously eye signs of global greenhouse warming, climatologists are finding the best evidence yet that a massive volcanic eruption can temporarily bring the temperature down a notch or two. Such a cooling could be enough to set the current global warming back more than a decade, confusing any efforts to link it to the greenhouse effect. By effectively eliminating some nonvolcanic climate changes from the record of the past 100 years, researchers have detected drops in global temperature of several tenths of a degree within 1 to 2 years of volcanic eruptions. Apparently, the debris spewed into the stratosphere blocked sunlight and caused the temperature drops. For all their potential social significance, the climate effects of volcanoes have been hard to detect. The problem has been in identifying a volcanic cooling among the nearly continuous climate warmings and coolings of a similar size that fill the record. The paper reviews how this was done.

  14. The Mediterranean Supersite Volcanoes (MED-SUV) Project: an overview

    NASA Astrophysics Data System (ADS)

    Puglisi, Giuseppe

    2013-04-01

    In response to the EC call ENV.2012.6.4-2 (Long-term monitoring experiments in geologically active regions of Europe prone to natural hazards: the Supersite concept - FP7-ENV-2012-two-stage) a wide community of volcanological institutions proposed the project Mediterranean Supersite Volcanoes (MED-SUV), which is in the negotiation phase at the time of writing. The Consortium is composed by 18 European University and research institutes, four Small or Medium Enterprises (SME) and two non-European University and research institutes. MED-SUV will improve the consortium capacity of assessment of volcanic hazards in Supersites of Southern Italy by optimising and integrating existing and new observation/monitoring systems, by a breakthrough in understanding of volcanic processes and by increasing the effectiveness of the coordination between the scientific and end-user communities. More than 3 million of people are exposed to potential volcanic hazards in a large region in the Mediterranean Sea, where two among the largest European volcanic areas are located: Mt. Etna and Campi Flegrei/Vesuvius. This project will fully exploit the unique detailed long-term in-situ monitoring data sets available for these volcanoes and integrate with Earth Observation (EO) data, setting the basic tools for a significant step ahead in the discrimination of pre-, syn- and post-eruptive phases. The wide range of styles and intensities of volcanic phenomena observed on these volcanoes, which can be assumed as archetypes of 'closed conduit ' and 'open conduit' volcano, together with the long-term multidisciplinary data sets give an exceptional opportunity to improve the understanding of a very wide spectrum of geo-hazards, as well as implementing and testing a large variety of innovative models of ground deformation and motion. Important impacts on the European industrial sector are expected, arising from a partnership integrating the scientific community and SMEs to implement together new

  15. The hydrogeology of Kilauea volcano

    SciTech Connect

    Ingebritsen, S.E.; Scholl, M.A. )

    1993-08-01

    The hydrogeology of Kilauea volcano and adjacent areas has been studied since the turn of this century. However, most studies to date have focused on the relatively shallow, low-salinity parts of the ground-water system, and the deeper hydrothermal system remains poorly understood. The rift zones of adjacent Mauna Loa volcano bound the regional ground-water flow system that includes Kilauea, and the area bounded by the rift zones of Kilauea and the ocean may comprise a partly isolated subsystem. Rates of ground-water recharge vary greatly over the area, and discharge is difficult to measure, because streams are ephemeral and most ground-water discharges diffusely at or below sea level. Hydrothermal systems exist at depth in Kilauea's east and southwest rift zone, as evidenced by thermal springs at the coast and wells in the lower east-rift zone. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones. Available data suggest that dike-impounded, heated ground water occurs at relatively high elevations in the upper east- and southwest-rift zones of Kilauea, and that permeability at depth in the rift zones (probably [le]10[sup [minus]15] m[sup 2]) is much lower than that of unaltered basalt flows closer to the surface ([ge]10[sup [minus]10] m[sup 2]). Substantial variations in permeability and the presence of magmatic heat sources influence that structure of the fresh water-salt water interface, so the Ghyben-Herzberg model will often fail to predict its position. Numerical modeling studies have considered only subsets of the hydrothermal system, because no existing computer code solves the coupled fluid-flow, heat- and solute-transport problem over the temperature and salinity range encountered at Kilauea. 73 refs., 7 figs., 2 tabs.

  16. Insights into the dynamics of Etna volcano from 20-year time span microgravity and GPS observations

    NASA Astrophysics Data System (ADS)

    Bonforte, Alessandro; Fanizza, Giovanni; Greco, Filippo; Matera, Alfredo; Sulpizio, Roberto

    2016-04-01

    A common ground deformation and microgravity array of benchmarks lies on the southern slope of Mt. Etna volcano and is routinely measured by GPS and relative gravimetry methods. The array was installed for monitoring the ground motion and underground mass changes along the southern rift of the volcano and data are usually processed and interpreted independently. The benchmarks have been installed mainly along a main road crossing the southern side of the volcano with an E-W direction and reaching 2000 m of altitude. The gravity array covers the entire path of the road, while the ground deformation one only the upper one, due to the woods at lower altitude preventing good GPS measurements. Furthermore, microgravity surveys are usually carried out more frequently with respect to the GPS ones. In this work, an integrated analysis of microgravity and ground deformation is performed over a 20-year time span (1994-2014). Gravity variations have been first corrected for the free-air effect using the GPS observed vertical deformation and the theoretical vertical gravity gradient (-308.6 μGal/m). The free-air corrected gravity changes were then reduced from the high frequency variations (noise) and the seasonal fluctuations, mainly due to water-table fluctuations. This long-term dataset constitutes a unique opportunity to examine the behavior of Etna in a period in which the volcano exhibited different styles of activity characterized by recharging phases, flank eruptions and fountaining episodes. The gravity and deformation data allow investigating the response of the volcano in a wider perspective providing insights into the definition of its dynamic behavior and posing the basis to track the unrest evolution and to forecast the style of the eruption. The joint analysis highlights common periods, in which the signals underwent contemporaneous changes occurring mainly in the central and eastern stations. On the other hand, no significant changes in the behavior of

  17. Volcano flank instability in the Lesser Antilles Arc: Diversity of scale, processes, and temporal recurrence

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Le Friant, Anne; Komorowski, Jean-Christophe; Deplus, Christine; Semet, Michel P.

    2007-08-01

    The 1997 Boxing Day collapse, a remarkable feature of the ongoing eruption of Soufrière Hills on Montserrat, has prompted new interest in the study of volcano stability in the Lesser Antilles. Building on a few cases documented in the literature, we have now identified at least 47 flank collapse events on volcanoes of the Caribbean arc where this type of behavior is characteristic and repetitive. About 15 events occurred on active volcanoes within the last 12,000 years. In the northern part of the arc, flank collapses are repetitive, do not exceed 1 km3 in volume, occur in all directions, and are promoted by intense hydrothermal alteration and well-developed fracturing of the summit part of the edifices. In contrast, infrequent but large sector collapses, with volumes up to tens of km3, are typical of the southern volcanoes. They are always directed to the west as a result of the high overall slopes of the islands toward the deep back-arc Grenada Basin. Because Caribbean islands are small, a large part of the resulting debris avalanches have flowed into the sea thus contributing voluminous and sudden inputs of volcaniclastic sediments to the Grenada Basin. Deposits from such submarine flows have been identified during the recent AGUADOMAR and CARAVAL oceanographic cruises and traced to their source structures on land. Edifice collapses have a major influence on subsequent volcanic activity but also are of high concern because of their tsunamigenic potential.

  18. Contrasting andesitic magmatic systems in adjacent North Island volcanoes, New Zealand: implications for predicting eruptions

    NASA Astrophysics Data System (ADS)

    Price, R. C.; Smith, I. E.; Gamble, J. A.; Moebis, A.; Cronin, S. J.

    2011-12-01

    For active or dormant andesite volcanoes, detailed, stratigraphically controlled, geochemical and petrological information enables an understanding of the magma supply and plumbing system feeding eruptions at the surface. This can establish a basis for predictive eruption models and thus for hazard prediction and management. The potential for petrography to inform volcanic hazard management is demonstrated by comparing two andesitic volcanoes located at the southern end of the Taupo Volcanic Zone in New Zealand's North Island. Ngauruhoe has been constructed over the past 3-5 ka and last erupted in 1975. Nearby Ruapehu has a much longer eruptive history extending back beyond 230 ka B.P. Despite their close spatial proximity, the two volcanoes show geochemical contrasts suggesting that each magmatic system has operated separately. The petrology and geochemistry (major and trace element chemistry, U-series isotopes, Sr and Nd isotopes) of eruptives from each volcano reflect magma evolution in a complex magma storage and plumbing system with magma chemistry strongly influenced by fractional crystallisation and crustal assimilation but in the case of Ngauruhoe there is evidence for cyclicity in the evolution of magma batches and this appears to be driven by periodic replenishment of the magmatic system from the mantle. In contrast, the past 2 ka of eruptive history at Ruapehu reflects random tapping of shallow, volume magma reservoirs.

  19. Wide Angle View of Arsia Mons Volcano

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Arsia Mons (above) is one of the largest volcanoes known. This shield volcano is part of an aligned trio known as the Tharsis Montes--the others are Pavonis Mons and Ascraeus Mons. Arsia Mons is rivaled only by Olympus Mons in terms of its volume. The summit of Arsia Mons is more than 9 kilometers (5.6 miles) higher than the surrounding plains. The crater--or caldera--at the volcano summit is approximately 110 km (68 mi) across. This view of Arsia Mons was taken by the red and blue wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera (MOC) system. Bright water ice clouds (the whitish/bluish wisps) hang above the volcano--a common sight every martian afternoon in this region. Arsia Mons is located at 120o west longitude and 9o south latitude. Illumination is from the left.

  20. Halogen Oxide Measurements at Masaya Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Kern, C.; Vogel, L.; Sihler, H.; Rivera, C.; Strauch, W.; Galle, B.; Platt, U.

    2007-12-01

    Sulphur dioxide (SO2) and halogen oxide emissions were measured at Masaya Volcano in Nicaragua in April 2007 using differential optical absorption spectroscopy (DOAS). Next to passive DOAS measurements using scattered sunlight, an active long-path DOAS system was operated for several days with the light beam crossing the crater of the volcano. These measurements for the first time give an insight into the night-time halogen chemistry occurring at volcanoes. While the passive DOAS instruments measured sulphur dioxide (SO2) and bromine monoxide (BrO) in various viewing geometries and distances from the crater during daytime, the active instrument additionally allowed a quantification of chlorine monoxide (ClO) and chlorine dioxide (OClO), as well as being able to measure round-the-clock. The results of the field measurements will be presented and their implications for halogen chemistry at volcanoes will be discussed.

  1. Lahar hazards at Agua volcano, Guatemala

    USGS Publications Warehouse

    Schilling, S.P.; Vallance, J.W.; Matías, O.; Howell, M.M.

    2001-01-01

    At 3760 m, Agua volcano towers more than 3500 m above the Pacific coastal plain to the south and 2000 m above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers (km) of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 km of Escuintla (population, ca. 100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debris—also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

  2. Radial anisotropy ambient noise tomography of volcanoes

    NASA Astrophysics Data System (ADS)

    Mordret, Aurélien; Rivet, Diane; Shapiro, Nikolai; Jaxybulatov, Kairly; Landès, Matthieu; Koulakov, Ivan; Sens-Schönfelder, Christoph

    2016-04-01

    The use of ambient seismic noise allows us to perform surface-wave tomography of targets which could hardly be imaged by other means. The frequencies involved (~ 0.5 - 20 s), somewhere in between active seismic and regular teleseismic frequency band, make possible the high resolution imaging of intermediate-size targets like volcanic edifices. Moreover, the joint inversion of Rayleigh and Love waves dispersion curves extracted from noise correlations allows us to invert for crustal radial anisotropy. We present here the two first studies of radial anisotropy on volcanoes by showing results from Lake Toba Caldera, a super-volcano in Indonesia, and from Piton de la Fournaise volcano, a hot-spot effusive volcano on the Réunion Island (Indian Ocean). We will see how radial anisotropy can be used to infer the main fabric within a magmatic system and, consequently, its dominant type of intrusion.

  3. A field guide to Newberry Volcano, Oregon

    USGS Publications Warehouse

    Jenson, Robert A.; Donnelly-Nolan, Julie M.; McKay, Daniele

    2009-01-01

    Newberry Volcano is located in central Oregon at the intersection of the Cascade Range and the High Lava Plains. Its lavas range in age from ca. 0.5 Ma to late Holocene. Erupted products range in composition from basalt through rhyolite and cover ~3000 km2. The most recent caldera-forming eruption occurred ~80,000 years ago. This trip will highlight a revised understanding of the volcano's history based on new detailed geologic work. Stops will also focus on evidence for ice and flooding on the volcano, as well as new studies of Holocene mafic eruptions. Newberry is one of the most accessible U.S. volcanoes, and this trip will visit a range of lava types and compositions including tholeiitic and calc-alkaline basalt flows, cinder cones, and rhyolitic domes and tuffs. Stops will include early distal basalts as well as the youngest intracaldera obsidian flow.

  4. Economic geology: Ore metals beneath volcanoes

    NASA Astrophysics Data System (ADS)

    Nadeau, Olivier

    2015-03-01

    Metals often accumulate in the crust beneath volcanoes. Laboratory experiments and observations reveal important roles for magmatic vapours and brines in transporting and concentrating the metals into deposits worth targeting for extraction.

  5. Lahar hazards at Mombacho Volcano, Nicaragua

    USGS Publications Warehouse

    Vallance, J.W.; Schilling, S.P.; Devoli, G.

    2001-01-01

    Mombacho volcano, at 1,350 meters, is situated on the shores of Lake Nicaragua and about 12 kilometers south of Granada, a city of about 90,000 inhabitants. Many more people live a few kilometers southeast of Granada in 'las Isletas de Granada and the nearby 'Peninsula de Aseses. These areas are formed of deposits of a large debris avalanche (a fast moving avalanche of rock and debris) from Mombacho. Several smaller towns with population, in the range of 5,000 to 12,000 inhabitants are to the northwest and the southwest of Mombacho volcano. Though the volcano has apparently not been active in historical time, or about the last 500 years, it has the potential to produce landslides and debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas. -- Vallance, et.al., 2001

  6. Eruption of Alaska volcano breaks historic pattern

    USGS Publications Warehouse

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

    2009-01-01

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

  7. Repeating volcano-tectonic earthquakes at Mt. Etna volcano (Sicily, Italy): characterization and evidences of crustal changes

    NASA Astrophysics Data System (ADS)

    Cannata, Andrea; Alparone, Salvatore; Ursino, Andrea

    2014-05-01

    Repeating volcano-tectonic (VT) earthquakes, taking place at Mt. Etna during 1999-2009, were detected and analyzed to investigate their behavior. We found 735 families amounting to 2479 VT earthquakes, representing ~38% of all the analyzed VT earthquakes. Over 70% of the families comprise 2 or 3 VT earthquakes and only 20 families by more than 10 events. More than half of the families have a lifetime shorter than 0.5 day and only ~10% longer than 1 year. On the basis of these results, most of the detected families were considered 'burst-type', i.e., show swarm-like occurrence, and hence their origin cannot be explained by a temporally constant tectonic loading. Indeed, since the analyzed earthquakes take place in a volcanic area, the rocks are affected not only by tectonic stresses related to the fairly steady regional stress field but also by local stresses, caused by the volcano, such as magma batch intrusions/movements and gravitational loading. We focused on five groups of families characterized by the best repeatability over time, namely high number of events and long lifetime, located in the north-eastern, eastern and southern flanks of the volcano. Unlike the first four groups, which similarly to most of the detected families show swarm-like VT occurrences, group 'v', located in the north-eastern sector, exhibits a more 'tectonic' behavior with the events making up such a group spread over almost the entire analyzed period. It is clear how both occurrence and slip rates do not remain constant but vary over time, and such changes are time-related to the occurrence of the 2002-2003 eruption. We searched for waveform variations in VT earthquakes belonging to the group 'v' and found changes that took place mainly in the 2002-2003 period. These consisted in a decreasing similarity of the late seismogram windows, highlighted by cross correlation analysis, as well as in delays, increasing proportionally to lapse time, detected by coda wave interferometry. Such

  8. Widespread and Compositionally Diverse Magmatism Characterizes Late Holocene Time at Medicine Lake Volcano, California

    NASA Astrophysics Data System (ADS)

    Donnelly-Nolan, J. M.; Grove, T. L.

    2013-12-01

    Medicine Lake volcano in the southern Cascades is a high priority target for monitoring by the USGS Volcano Hazards Program. Ongoing subsidence focused on the central caldera along with fumarolic activity and an active geothermal system, as well as intermittent long-period seismic events indicate that the volcano is likely to erupt again. Nine eruptions have taken place at this very large rear-arc volcano since 5200 years ago. Their vents were widely distributed, scattered over an area of about 300 square km across the 2000-square-km volcano. The eruptions are well dated and occurred in three episodes at about 5 ka, 3 ka, and 1 ka. A remarkably diverse array of magmas ranging from basalt through rhyolite is represented. The 5-ka episode produced two caldera-focused dacitic eruptions. At ~3 ka, a north flank tholeiitic basalt eruption was followed by eruption of a south flank andesite. The 1-ka final episode produced a variety of compositions including west- and north-flank calc-alkaline mafic flows interspersed with fissure rhyolites erupted tangential to the caldera. The youngest and most spectacular rhyolite, and the youngest eruption at the volcano, is the 950-yr-old Glass Mountain flow. Quenched mafic 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. The mafic lavas and inclusions include both tholeiitic and calc-alkaline types and record complicated petrogenetic histories. Experimental evidence suggests that magmas were stored at 3-6 km prior to eruption, and that both wet and dry parental magmas were involved in generating the more silicic magmas. All eruptions took place from NW- to NE-trending alignments of vents, reflecting the overall E-W extensional tectonic environment. The interaction of tectonism and volcanism is a dominant influence at this subduction-related volcano, located

  9. Major Martian Volcanoes from MOLA - Olympus Mons

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Two views of Olympus Mons, shown as topography draped over a Viking image mosaic. MOLA's regional topography has shown that this volcano sits off to the west of the main Tharsis rise rather than on its western flank. The topography also clearly shows the relationship between the volcano's scarp and massive aureole deposit that was produced by flank collapse. The vertical exaggeration is 10:1.

  10. Volcano Inflation prior to Gas Explosions at Semeru Volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Nishimura, T.; Iguchi, M.; Kawaguchi, R.; Surono, S.; Hendrasto, M.; Rosadi, U.

    2010-12-01

    Semeru volcano in east Java, Indonesia, is well known to exhibit small vulcanian eruptions at the summit crater. Such eruptive activity stopped on April 2009, but volcanic earthquakes started to occur in August and a lava dome was found in the summit crater on November. Since then, lava sometimes flows downward on the slope and small explosions emitting steams from active crater frequently occur every a few to a few tens of minutes. Since the explosions repeatedly occur with short intervals and the active crater is located close to the summit with an altitude of 3676m, the explosions are considered to originate from the gas (steams) from magma itself in the conduit and not to be caused by interactions of magma with the underground water. We installed a tiltmeter at the summit on March 2010 to study the volcanic eruption mechanisms. The tiltmeter (Pinnacle hybrid type, accuracy of measurement is 1 nrad ) was set at a depth of about 1 m around the summit about 500 m north from the active crater. The data stored every 1 s in the internal memory was uploaded every 6 hours by a small data logger with GPS time correction function. More than one thousand gas explosion events were observed for about 2 weeks. We analyze the tilt records as well as seismic signals recorded at stations of CVGHM, Indonesia. The tilt records clearly show uplift of the summit about 20 to 30 seconds before each explosion. Uplifts before large explosions reach to about 20 - 30 n rad, which is almost equivalent to the volume increase of about 100 m^3 beneath the crater. To examine the eruption magnitude dependence on the uplift, we classify the eruptions into five groups based on the amplitudes of seismograms associated with explosions. We stack the tilt records for these groups to reduce noises in the signals and to get general characteristics of the volcano inflations. The results show that the amplitudes of uplifts are almost proportional to the amplitudes of explosion earthquakes while the

  11. Evolution of large shield volcanoes on Venus

    NASA Technical Reports Server (NTRS)

    Herrick, Robert R.; Dufek, Josef; McGovern, Patrick J.

    2005-01-01

    We studied the geologic history, topographic expression, and gravity signature of 29 large Venusian shield volcanoes with similar morphologies in Magellan synthetic aperture radar imagery. While they appear similar in imagery, 16 have a domical topographic expression and 13 have a central depression. Typical dimensions for the central depression are 150 km wide and 500 m deep. The central depressions are probably not calderas resulting from collapse of a shallow magma chamber but instead are the result of a corona-like sagging of a previously domical volcano. The depressions all have some later volcanic filling. All but one of the central depression volcanoes have been post-dated by geologic features unrelated to the volcano, while most of the domical volcanoes are at the top of the stratigraphic column. Analysis of the gravity signatures in the spatial and spectral domains shows a strong correlation between the absence of post-dating features and the presence of dynamic support by an underlying plume. We infer that the formation of the central depressions occurred as a result of cessation of dynamic support. However, there are some domical volcanoes whose geologic histories and gravity signatures also indicate that they are extinct, so sagging of the central region apparently does not always occur when dynamic support is removed. We suggest that the thickness of the elastic lithosphere may be a factor in determining whether a central depression forms when dynamic support is removed, but the gravity data are of insufficient resolution to test this hypothesis with admittance methods.

  12. Southern Rains

    Atmospheric Science Data Center

    2014-05-15

    ...   View Larger image Vigorous vegetation growth in the Southern United States after heavy rains fell during April and ... for atmospheric scattering and absorption effects, and use plant canopy structural models to determine the partitioning of solar ...

  13. Mud Volcanoes - Analogs to Martian Cones and Domes (by the Thousands!)

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy

    2010-01-01

    Mud volcanoes are mounds formed by low temperature slurries of gas, liquid, sediments and rock that erupt to the surface from depths of meters to kilometers. They are common on Earth, with estimates of thousands onshore and tens of thousands offshore. Mud volcanoes occur in basins with rapidly-deposited accumulations of fine-grained sediments. Such settings are ideal for concentration and preservation of organic materials, and mud volcanoes typically occur in sedimentary basins that are rich in organic biosignatures. Domes and cones, cited as possible mud volcanoes by previous authors, are common on the northern plains of Mars. Our analysis of selected regions in southern Acidalia Planitia has revealed over 18,000 such features, and we estimate that more than 40,000 occur across the area. These domes and cones strongly resemble terrestrial mud volcanoes in size, shape, morphology, associated flow structures and geologic setting. Geologic and mineralogic arguments rule out alternative formation mechanisms involving lava, ice and impacts. We are studying terrestrial mud volcanoes from onshore and submarine locations. The largest concentration of onshore features is in Azerbaijan, near the western edge of the Caspian Sea. These features are typically hundreds of meters to several kilometers in diameter, and tens to hundreds of meters in height. Satellite images show spatial densities of 20 to 40 eruptive centers per 1000 square km. Many of the features remain active, and fresh mud flows as long as several kilometers are common. A large field of submarine mud volcanoes is located in the Gulf of Cadiz, off the Atlantic coasts of Morocco and Spain. High-resolution sonar bathymetry reveals numerous km-scale mud volcanoes, hundreds of meters in height. Seismic profiles demonstrate that the mud erupts from depths of several hundred meters. These submarine mud volcanoes are the closest morphologic analogs yet found to the features in Acidalia Planitia. We are also conducting

  14. Earthquakes - Volcanoes (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2013-04-01

    Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is

  15. Earthquakes - Volcanoes (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2015-04-01

    Earthquakes and volcanoes are caused by: 1) Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2) Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3) The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is

  16. EARTHQUAKES - VOLCANOES (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2014-05-01

    Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is

  17. Arsia Mons Southern Flank

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The final VIS image of Arsia Mons is located on the southern flank of the volcano adjacent to the NE trending feature. There has been a significant amount of collapse features formed in this region.

    Image information: VIS instrument. Latitude -11.1, Longitude 238.6 East (121.4 West). 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  18. An Admittance Survey of Large Volcanoes on Venus: Implications for Volcano Growth

    NASA Technical Reports Server (NTRS)

    Brian, A. W.; Smrekar, S. E.; Stofan, E. R.

    2004-01-01

    Estimates of the thickness of the venusian crust and elastic lithosphere are important in determining the rheological and thermal properties of Venus. These estimates offer insights into what conditions are needed for certain features, such as large volcanoes and coronae, to form. Lithospheric properties for much of the large volcano population on Venus are not well known. Previous studies of elastic thickness (Te) have concentrated on individual or small groups of edifices, or have used volcano models and fixed values of Te to match with observations of volcano morphologies. In addition, previous studies use different methods to estimate lithospheric parameters meaning it is difficult to compare their results. Following recent global studies of the admittance signatures exhibited by the venusian corona population, we performed a similar survey into large volcanoes in an effort to determine the range of lithospheric parameters shown by these features. This survey of the entire large volcano population used the same method throughout so that all estimates could be directly compared. By analysing a large number of edifices and comparing our results to observations of their morphology and models of volcano formation, we can help determine the controlling parameters that govern volcano growth on Venus.

  19. Interagency collaboration on an active volcano: a case study at Hawai‘i Volcanoes National Park

    USGS Publications Warehouse

    Kauahikaua, James P.; Orlando, Cindy

    2014-01-01

    Because Kilauea and Mauna Loa are included within the National Park, there is a natural intersection of missions for the National Park Service (NPS) and the U.S. Geological Survey (USGS). HAVO staff and the USGS Hawaiian Volcano Observatory scientists have worked closely together to monitor and forecast multiple eruptions from each of these volcanoes since HAVO’s founding in 1916.

  20. Spreading and collapse of big basaltic volcanoes

    NASA Astrophysics Data System (ADS)

    Puglisi, Giuseppe; Bonforte, Alessandro; Guglielmino, Francesco; Peltier, Aline; Poland, Michael

    2016-04-01

    Among the different types of volcanoes, basaltic ones usually form the most voluminous edifices. Because volcanoes are growing on a pre-existing landscape, the geologic and structural framework of the basement (and earlier volcanic landforms) influences the stress regime, seismicity, and volcanic activity. Conversely, the masses of these volcanoes introduce a morphological anomaly that affects neighboring areas. Growth of a volcano disturbs the tectonic framework of the region, clamps and unclamps existing faults (some of which may be reactivated by the new stress field), and deforms the substratum. A volcano's weight on its basement can trigger edifice spreading and collapse that can affect populated areas even at significant distance. Volcano instability can also be driven by slow tectonic deformation and magmatic intrusion. The manifestations of instability span a range of temporal and spatial scales, ranging from slow creep on individual faults to large earthquakes affecting a broad area. In the frame of MED-SVU project, our work aims to investigate the relation between basement setting and volcanic activity and stability at three Supersite volcanoes: Etna (Sicily, Italy), Kilauea (Island of Hawaii, USA) and Piton de la Fournaise (La Reunion Island, France). These volcanoes host frequent eruptive activity (effusive and explosive) and share common features indicating lateral spreading and collapse, yet they are characterized by different morphologies, dimensions, and tectonic frameworks. For instance, the basaltic ocean island volcanoes of Kilauea and Piton de la Fournaise are near the active ends of long hotspot chains while Mt. Etna has developed at junction along a convergent margin between the African and Eurasian plates and a passive margin separating the oceanic Ionian crust from the African continental crust. Magma supply and plate velocity also differ in the three settings, as to the sizes of the edifices and the extents of their rift zones. These

  1. Nyiragongo Volcano before the Eruption

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  2. 3-D Resistivity Structure of La Soufrière Volcano (Guadeloupe): New Insights into the Hydrothermal System and Associated Hazards

    NASA Astrophysics Data System (ADS)

    Rosas-Carbajal, M.; Nicollin, F.; Komorowski, J. C.; Gibert, D.; Deroussi, S.

    2015-12-01

    The 3-D electrical resistivity model of the dome of La Soufrière of Guadeloupe volcano was obtained by inverting more than 23000 electrical resistivity tomography (ERT) and mise-a-la-masse data points. Data acquisition involved 2-D and 3-D protocols, including several pairs of injection electrodes located on opposite sides of the volcano. For the mise-a-la-masse measurements, the contact with a conductive mass was achieved by immersing one of the current electrodes in the Tarissan acid pond (~25 Siemens/m) located in the volcano's summit. The 3-D inversion was performed using a deterministic smoothness-constrained least-squares algorithm with unstructured grid modeling to accurately account for topography. Resistivity contrasts of more than 4 orders of magnitude are observed. A thick and high-angle conductive structure is located in the volcano's southern flank. It extends from the Tarissan Crater's acid pond on the summit to a hot spring region located close to the dome's southern base. This suggests that a large hydrothermal reservoir is located below the southern base of the dome, and connected to the acid pond of the summit's main crater. Therefore, the steep southern flanks of the volcano could be resting on a low-strength, high-angle discontinuity saturated with circulating and possibly pressurized hydrothermal fluids. This could favor partial edifice collapse and lateral directed explosions as shown recurrently in the volcano's history. The resistivity model also reveals smaller hydrothermal reservoirs in the south-east and northern flanks that are linked to the main historical eruptive fractures and to ancient collapse structures such as the Cratère Amic structure. We discuss the main resistivity structures in relation with the geometry of observed faults, historical eruptive fractures, the dynamics of the near surface hydrothermal system manifestations on the dome and the potential implications for future hazards scenarios .

  3. Seismicity of southern Lake Tanganyika

    NASA Astrophysics Data System (ADS)

    Lavayssiere, A.; Gallacher, R. J.; Keir, D.; Ebinger, C. J.; Drooff, C.; Khalfan, M.; Bull, J. M.

    2015-12-01

    Global seismic networks document frequent and unusually deep earthquakes in East African rift sectors lacking central volcanoes. The deep seismicity means that we can use earthquakes to probe the geometry and kinematics of fault systems throughout the crust, and to understand the distribution of strain between large offset border fault systems and intrabasinal faults. The southern Tanganyika rift zone has the highest seismicity rate within East Africa during the period 1973-present, yet earlier temporary seismometer networks have been too sparse in space and time to relocate earthquakes with location and depth errors of < 5-10 km. We address this issue by recording seismicity of southern Lake Tanganyika since June 2014 using a network at 12 broadband seismic stations. The distribution of earthquakes shows that deformation primarily occurs on large offset border faults beneath the lake. Subsidiary earthquake activity occurs along the subparrallel Rukwa graben, and beneath the NE-SW striking Mweru rift. The distribution of earthquakes suggests the southern end of lake Tanganyika is characterized by a network of intersecting NNW and NE striking faults. The depths of earthquakes are distributed throughout the crust, consistent with the relatively strong lithosphere.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  5. Tephrochronology of the southernmost Andean Southern Volcanic Zone, Chile

    NASA Astrophysics Data System (ADS)

    Weller, D. J.; Miranda, C. G.; Moreno, P. I.; Villa-Martínez, R.; Stern, C. R.

    2015-12-01

    Correlations among and identification of the source volcanoes for over 60 Late Glacial and Holocene tephras preserved in eight lacustrine sediment cores taken from small lakes near Coyhaique, Chile (46° S), were made based on the stratigraphic position of the tephra in the cores, lithostratigraphic data (tephra layer thickness and grain size), and tephra petrochemistry (glass color and morphology, phenocryst phases, and bulk-tephra trace element contents determined by ICP-MS). The cores preserve a record of explosive eruptions, since ˜17,800 calibrated years before present (cal years BP), of the volcanoes of the southernmost Andean Southern Volcanic Zone (SSVZ). The suggested source volcanoes for 55 of these tephras include Hudson (32 events), Mentolat (10 events), and either Macá or Cay or some of the many minor monogenetic eruptive centers (MECs; 13 events) in the area. Only four of these eruptions had been previously identified in tephra outcrops in the region, indicating the value of lake cores for identifying smaller eruptions in tephrochronologic studies. The tephra records preserved in these lake cores, combined with those in marine cores, which extend these records back to 20,000 cal years BP, prior to the Last Glacial Maximum, suggest that no significant temporal change in the frequency of explosive eruptions was associated with deglaciation. Over this time period, Hudson volcano, one of the largest and longest lived volcanoes in the Southern Andes, has had >55 eruptions (four of them were very large) and has produced >45 km3 of pyroclastic material, making it also one of the most active volcanoes in the SVZ in terms of both frequency and volume of explosive eruptions.

  6. Characteristics and management of the 2006-2008 volcanic crisis at the Ubinas volcano (Peru)

    NASA Astrophysics Data System (ADS)

    Rivera, Marco; Thouret, Jean-Claude; Mariño, Jersy; Berolatti, Rossemary; Fuentes, José

    2010-12-01

    Ubinas volcano is located 75 km East of Arequipa and ca. 5000 people are living within 12 km from the summit. This composite cone is considered the most active volcano in southern Peru owing to its 24 low to moderate magnitude (VEI 1-3) eruptions in the past 500 years. The onset of the most recent eruptive episode occurred on 27 March 2006, following 8 months of heightened fumarolic activity. Vulcanian explosions occurred between 14 April 2006 and September 2007, at a time ejecting blocks up to 40 cm in diameter to distances of 2 km. Ash columns commonly rose to 3.5 km above the caldera rim and dispersed fine ash and aerosols to distances of 80 km between April 2006 and April 2007. Until April 2007, the total volume of ash was estimated at 0.004 km 3, suggesting that the volume of fresh magma was small. Ash fallout has affected residents, livestock, water supplies, and crop cultivation within an area of ca. 100 km 2 around the volcano. Continuous degassing and intermittent mild vulcanian explosions lasted until the end of 2008. Shortly after the initial explosions on mid April 2006 that spread ash fallout within 7 km of the volcano, an integrated Scientific Committee including three Peruvian institutes affiliated to the Regional Committee of Civil Defense for Moquegua, aided by members of the international cooperation, worked together to: i) elaborate and publish volcanic hazard maps; ii) inform and educate the population; and iii) advise regional authorities in regard to the management of the volcanic crisis and the preparation of contingency plans. Although the 2006-2008 volcanic crisis has been moderate, its management has been a difficult task even though less than 5000 people now live around the Ubinas volcano. However, the successful management has provided experience and skills to the scientific community. This volcanic crisis was not the first one that Peru has experienced but the 2006-2008 experience is the first long-lasting crisis that the Peruvian civil

  7. Effects of Volcanoes on the Natural Environment

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, Peter J.

    2005-01-01

    The primary focus of this project has been on the development of techniques to study the thermal and gas output of volcanoes, and to explore our options for the collection of vegetation and soil data to enable us to assess the impact of this volcanic activity on the environment. We originally selected several volcanoes that have persistent gas emissions and/or magma production. The investigation took an integrated look at the environmental effects of a volcano. Through their persistent activity, basaltic volcanoes such as Kilauea (Hawaii) and Masaya (Nicaragua) contribute significant amounts of sulfur dioxide and other gases to the lower atmosphere. Although primarily local rather than regional in its impact, the continuous nature of these eruptions means that they can have a major impact on the troposphere for years to decades. Since mid-1986, Kilauea has emitted about 2,000 tonnes of sulfur dioxide per day, while between 1995 and 2000 Masaya has emotted about 1,000 to 1,500 tonnes per day (Duffel1 et al., 2001; Delmelle et al., 2002; Sutton and Elias, 2002). These emissions have a significant effect on the local environment. The volcanic smog ("vog" ) that is produced affects the health of local residents, impacts the local ecology via acid rain deposition and the generation of acidic soils, and is a concern to local air traffic due to reduced visibility. Much of the work that was conducted under this NASA project was focused on the development of field validation techniques of volcano degassing and thermal output that could then be correlated with satellite observations. In this way, we strove to develop methods by which not only our study volcanoes, but also volcanoes in general worldwide (Wright and Flynn, 2004; Wright et al., 2004). Thus volcanoes could be routinely monitored for their effects on the environment. The selected volcanoes were: Kilauea (Hawaii; 19.425 N, 155.292 W); Masaya (Nicaragua; 11.984 N, 86.161 W); and Pods (Costa Rica; 10.2OoN, 84.233 W).

  8. Gravity model studies of Newberry Volcano, Oregon

    SciTech Connect

    Gettings, M.E.; Griscom, A.

    1988-09-10

    Newberry, Volcano, a large Quaternary volcano located about 60 km east of the axis of the High Cascades volcanoes in central Oregon, has a coincident positive residual gravity anomaly of about 12 mGals. Model calculations of the gravity anomaly field suggest that the volcano is underlain by an intrusive complex of mafic composition of about 20-km diameter and 2-km thickness, at depths above 4 km below sea level. However, uplifted basement in a northwest trending ridge may form part of the underlying excess mass, thus reducing the volume of the subvolcanic intrusive. A ring dike of mafic composition is inferred to intrude to near-surface levels along the caldera ring fractures, and low-density fill of the caldera floor probably has a thickness of 0.7--0.9 km. The gravity anomaly attributable to the volcano is reduced to the east across a north-northwest trending gravity anomaly gradient through Newberry caldera and suggests that normal, perhaps extensional, faulting has occurred subsequent to caldera formation and may have controlled the location of some late-stage basaltic and rhyolitic eruptions. Significant amounts of felsic intrusive material may exist above the mafic intrusive zone but cannot be resolved by the gravity data.

  9. Interferometric Synthetic Aperture radar studies of Alaska volcanoes

    USGS Publications Warehouse

    Lu, Zhong; Wicks, Charles W., Jr.; Dzurisin, Daniel; Power, John A.; Thatcher, Wayne R.; Masterlark, Timothy

    2003-01-01

    In this article, we summarize our recent InSAR studies of 13 Alaska volcanoes, including New Trident, Okmok, Akutan, Kiska, Augustine, Westdahl, Peulik, Makushin, Seguam, Shishaldin, Pavlof, Cleveland, and Korovin volcanoes.

  10. Volcanoes in the Classroom--an Explosive Learning Experience.

    ERIC Educational Resources Information Center

    Thompson, Susan A.; Thompson, Keith S.

    1996-01-01

    Presents a unit on volcanoes for third- and fourth-grade students. Includes demonstrations; video presentations; building a volcano model; and inviting a scientist, preferably a vulcanologist, to share his or her expertise with students. (JRH)

  11. Eruptive and geomorphic processes at the Lathrop Wells scoria cone volcano

    NASA Astrophysics Data System (ADS)

    Valentine, Greg A.; Krier, Donathan J.; Perry, Frank V.; Heiken, Grant

    2007-03-01

    The ˜ 80 ka Lathrop Wells volcano (southern Nevada, U.S.A.) preserves evidence for a range of explosive processes and emplacement mechanisms of pyroclastic deposits and lava fields in a small-volume basaltic center. Early cone building by Strombolian bursts was accompanied by development of a fan-like lava field reaching ˜ 800 m distance from the cone, built upon a gently sloping surface. Lava flows carried rafts of cone deposits, which provide indirect evidence for cone facies in lieu of direct exposures in the active quarry. Subsequent activity was of a violent Strombolian nature, with many episodes of sustained eruption columns up to a few km in height. These deposited layers of scoria lapilli and ash in different directions depending upon wind direction at the time of a given episode, reaching up to ˜ 20 km from the vent, and also produced the bulk of the scoria cone. Lava effusion migrated from south to north around the eastern base of the cone as accumulation of lavas successively reversed the topography at the base of the cone. Late lavas were emplaced during violent Strombolian activity and continued for some time after explosive eruptions had waned. Volumes of the eruptive products are: fallout — 0.07 km 3, scoria cone — 0.02 km 3, and lavas — 0.03 km 3. Shallow-derived xenolith concentrations suggest an upper bound on average conduit diameter of ˜ 21 m in the uppermost 335 m beneath the volcano. The volcano was constructed over a period of at least seven months with cone building occurring only during part of that time, based upon analogy with historical eruptions. Post-eruptive geomorphic evolution varied for the three main surface types that were produced by volcanic activity: (1) scoria cone, (2) low relief surfaces (including lavas) with abundant pyroclastic material, and (3) lavas with little pyroclastic material. The role of these different initial textures must be accounted for in estimating relative ages of volcanic surfaces, and failure

  12. The geochemical model of neutral and acidic thermal water in the Tatun Volcano Group, Taiwan

    NASA Astrophysics Data System (ADS)

    Tsai, Y.; Kuo, C.; Liu, C.

    2013-12-01

    The geochemical model can provide a quantitative method for water-rock interaction and understand the processes of neutralization of initially acidic water. The Tatun Volcano Group (TVG) is one of the Quaternary volcanoes of northern Taiwan. In the Southern Sulfur River of the TVG, it has neutral and acidic thermal water that can provide good materials for modeling the flow path of acidic and neutral thermal water. This study collects 7 thermal springs and identifies into two types, which are neutral and acidic thermal water. The host rock of neutral thermal water has fresh andesitic rock and is weak fumaroles, and the field observations of acidic thermal waters have been alternated andesitic rock and strong degassing fumaroles. The Geochemist's Workbench software (GWB) can model the processes of neutralization of initially acidic water. Furthermore, this study will collect the meteoric water, thermal springs, and country rock along the Southern Sulfur River and use the GWB software to model the processes of neutralization of initially acidic water in the Southern Sulfur River in the future.

  13. Nyerereite from calcite carbonatite at the Kerimasi Volcano, Northern Tanzania

    NASA Astrophysics Data System (ADS)

    Zaitsev, A. N.

    2010-12-01

    The extinct Quaternary Kerimasi volcano located in the southern part of the Gregory Rift, northern Tanzania, contains both intrusive and extrusive calciocarbonatites. One carbonate mineral with a high content of Na and Ca has been found in a sample of volcanic carbonatite, which is probably a cumulate rock. On the basis of Raman spectroscopy and SEM/EDS, this mineral was identified as nyerereite, ideally Na2Ca(CO3)2. It occurs as solid inclusions up to 300 × 200 μm in size in magnetite and contains (wt. %) 25.4-27.4 Na2O, 26.0-26.8 CaO, 1.6-1.9 K2O, 0.6-1.8 FeO, 0.3-0.6 SrO, <0.4 BaO, 1.4-2.3 SO3, and 0.6-0.9 P2O5. The average mineral formula is (Na1.84K0.08)Σ1.92(Ca1.00Fe0.03Sr0.01)Σ1.04[(CO3)1.91(SO4)0.05(PO4)0.02]Σ1.98. A few inclusions in magnetite also contain calcite, which is considered here to be a late-stage, subsolidus mineral. The occurrence of nyerereite in carbonatite supports Hay's (1983) idea that some of the extrusive carbonatites at the Kerimasi volcano were originally alkaline rich and contained both calcite and nyerereite as primary minerals.

  14. Kilauea volcano eruption seen from orbit

    NASA Technical Reports Server (NTRS)

    1993-01-01

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

  15. Predicting the Timing and Location of the next Hawaiian Volcano

    ERIC Educational Resources Information Center

    Russo, Joseph; Mattox, Stephen; Kildau, Nicole

    2010-01-01

    The wealth of geologic data on Hawaiian volcanoes makes them ideal for study by middle school students. In this paper the authors use existing data on the age and location of Hawaiian volcanoes to predict the location of the next Hawaiian volcano and when it will begin to grow on the floor of the Pacific Ocean. An inquiry-based lesson is also…

  16. How Do Volcanoes Affect Human Life? Integrated Unit.

    ERIC Educational Resources Information Center

    Dayton, Rebecca; Edwards, Carrie; Sisler, Michelle

    This packet contains a unit on teaching about volcanoes. The following question is addressed: How do volcanoes affect human life? The unit covers approximately three weeks of instruction and strives to present volcanoes in an holistic form. The five subject areas of art, language arts, mathematics, science, and social studies are integrated into…

  17. Living with Volcanoes: Year Eleven Teaching Resource Unit.

    ERIC Educational Resources Information Center

    Le Heron, Kiri; Andrews, Jill; Hooks, Stacey; Larnder, Michele; Le Heron, Richard

    2000-01-01

    Presents a unit on volcanoes and experiences with volcanoes that helps students develop geography skills. Focuses on four volcanoes: (1) Rangitoto Island; (2) Lake Pupuke; (3) Mount Smart; and (4) One Tree Hill. Includes an answer sheet and resources to use with the unit. (CMK)

  18. Three-dimensional Q for Sierra Negra volcano, Galapagos

    NASA Astrophysics Data System (ADS)

    Young, B. E.; Lees, J. M.; Ebinger, C. J.

    2012-12-01

    Galapagos Islands volcanoes are some of the most rapidly deforming volcanoes on Earth, yet the magma storage chambers and migration pathways are poorly imaged. Three-dimensional tomographic inversion for seismic attenuation, 1/Q, is used to image variations in subsurface structure and heterogeneity associated with magma storage and volcanic construction at Sierra Negra volcano, Galapagos Islands. P-wave power spectra were used to estimate t* (attenuation weighted, integrated slowness) in the frequency domain for local earthquakes recorded on the 15 station, broadband SIGNET array. The SIGNET network was deployed around Sierra Negra caldera and the southern part of Isabela Island between August 2009 and January 2011. A subset of 451 earthquakes was selected for attenuation analysis based on event location within the array and station coverage. The modelled spectra were used to calculate path attenuation and earthquake source parameters. The earthquake source parameters corresponding to amplitude at zero frequency (Ω0) and corner frequency (fc) relate to earthquake size and are therefore set constant across stations. Accordingly, we derive a single Ω0 and fc for each event and fix them while allowing only t* to vary. Values of t* range between 8.89 x 10-15 and 0.0525. Preliminary results show an increase in attenuation beneath the caldera starting at 1 km depth. The zone of high attenuation is more pronounced at 2 km depth and extends laterally to the east and southeast beyond the extent of the 10 km-wide caldera. Gravity anomaly and InSAR data has been used previously to model the magma chamber at Sierra Negra. Deformation modelling requires a flat-topped sill at 2 km depth (Geist et. al., 2007; Jonsson, S., 2009; Yun et. al., 2006). Our shallow, high attenuation zone matches these results, but also indicates that the attenuating bodies extend beyond the limits of the caldera beneath the SE flank of Sierra Negra. Elongate zones of higher attenuation correlate with

  19. Volcanoes muon imaging using Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Catalano, O.; Del Santo, M.; Mineo, T.; Cusumano, G.; Maccarone, M. C.; Pareschi, G.

    2016-01-01

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting of the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energy. Our new approach offers the advantage of a negligible background and an improved spatial resolution. To test the feasibility of our new method, we have carried out simulations with a toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging atmospheric Cherenkov telescope currently under installation onto the Etna volcano. Comparing the results of our simulations with previous experiments based on particle detectors, we gain at least a factor of 10 in sensitivity. The result of this study shows that we resolve an empty cylinder with a radius of about 100 m located inside a volcano in less than 4 days, which implies a limit on the magma velocity of 5 m/h.

  20. Volcano hazards program in the United States

    USGS Publications Warehouse

    Tilling, R.I.; Bailey, R.A.

    1985-01-01

    Volcano monitoring and volcanic-hazards studies have received greatly increased attention in the United States in the past few years. Before 1980, the Volcanic Hazards Program was primarily focused on the active volcanoes of Kilauea and Mauna Loa, Hawaii, which have been monitored continuously since 1912 by the Hawaiian Volcano Observatory. After the reawakening and catastrophic eruption of Mount St. Helens in 1980, the program was substantially expanded as the government and general public became aware of the potential for eruptions and associated hazards within the conterminous United States. Integrated components of the expanded program include: volcanic-hazards assessment; volcano monitoring; fundamental research; and, in concert with federal, state, and local authorities, emergency-response planning. In 1980 the David A. Johnston Cascades Volcano Observatory was established in Vancouver, Washington, to systematically monitor the continuing activity of Mount St. Helens, and to acquire baseline data for monitoring the other, presently quiescent, but potentially dangerous Cascade volcanoes in the Pacific Northwest. Since June 1980, all of the eruptions of Mount St. Helens have been predicted successfully on the basis of seismic and geodetic monitoring. The largest volcanic eruptions, but the least probable statistically, that pose a threat to western conterminous United States are those from the large Pleistocene-Holocene volcanic systems, such as Long Valley caldera (California) and Yellowstone caldera (Wyoming), which are underlain by large magma chambers still potentially capable of producing catastrophic caldera-forming eruptions. In order to become better prepared for possible future hazards associated with such historically unpecedented events, detailed studies of these, and similar, large volcanic systems should be intensified to gain better insight into caldera-forming processes and to recognize, if possible, the precursors of caldera-forming eruptions

  1. Mantle fault zone beneath Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Wolfe, C.J.; Okubo, P.G.; Shearer, P.M.

    2003-01-01

    Relocations and focal mechanism analyses of deep earthquakes (???13 kilometers) at Kilauea volcano demonstrate that seismicity is focused on an active fault zone at 30-kilometer depth, with seaward slip on a low-angle plane, and other smaller, distinct fault zones. The earthquakes we have analyzed predominantly reflect tectonic faulting in the brittle lithosphere rather than magma movement associated with volcanic activity. The tectonic earthquakes may be induced on preexisting faults by stresses of magmatic origin, although background stresses from volcano loading and lithospheric flexure may also contribute.

  2. Hot spot and trench volcano separations

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Schubert, G.

    1974-01-01

    It is suggested that the distribution of separations between trench volcanos located along subduction zones reflects the depth of partial melting, and that the separation distribution for hot spot volcanoes near spreading centers provides a measure of the depth of mantle convection cells. It is further proposed that the lateral dimensions of mantle convection cells are also represented by the hot-spot separations (rather than by ridge-trench distances) and that a break in the distribution of hot spot separations at 3000 km is evidence for both whole mantle convection and a deep thermal plume origin of hot spots.

  3. In search of ancestral Kilauea volcano

    USGS Publications Warehouse

    Lipman, P.W.; Sisson, T.W.; Ui, T.; Naka, J.

    2000-01-01

    Submersible observations and samples show that the lower south flank of Hawaii, offshore from Kilauea volcano and the active Hilina slump system, consists entirely of compositionally diverse volcaniclastic rocks; pillow lavas are confined to shallow slopes. Submarine-erupted basalt clasts have strongly variable alkalic and transitional basalt compositions (to 41% SiO2, 10.8% alkalies), contrasting with present-day Kilauea tholeiites. The volcaniclastic rocks provide a unique record of ancestral alkalic growth of an archetypal hotspot volcano, including transition to its tholeiitic shield stage, and associated slope-failure events.

  4. Venus small volcano classification and description

    NASA Technical Reports Server (NTRS)

    Aubele, J. C.

    1993-01-01

    The high resolution and global coverage of the Magellan radar image data set allows detailed study of the smallest volcanoes on the planet. A modified classification scheme for volcanoes less than 20 km in diameter is shown and described. It is based on observations of all members of the 556 significant clusters or fields of small volcanoes located and described by this author during data collection for the Magellan Volcanic and Magmatic Feature Catalog. This global study of approximately 10 exp 4 volcanoes provides new information for refining small volcano classification based on individual characteristics. Total number of these volcanoes was estimated to be 10 exp 5 to 10 exp 6 planetwide based on pre-Magellan analysis of Venera 15/16, and during preparation of the global catalog, small volcanoes were identified individually or in clusters in every C1-MIDR mosaic of the Magellan data set. Basal diameter (based on 1000 measured edifices) generally ranges from 2 to 12 km with a mode of 34 km, and follows an exponential distribution similar to the size frequency distribution of seamounts as measured from GLORIA sonar images. This is a typical distribution for most size-limited natural phenomena unlike impact craters which follow a power law distribution and continue to infinitely increase in number with decreasing size. Using an exponential distribution calculated from measured small volcanoes selected globally at random, we can calculate total number possible given a minimum size. The paucity of edifice diameters less than 2 km may be due to inability to identify very small volcanic edifices in this data set; however, summit pits are recognizable at smaller diameters, and 2 km may represent a significant minimum diameter related to style of volcanic eruption. Guest, et al, discussed four general types of small volcanic edifices on Venus: (1) small lava shields; (2) small volcanic cones; (3) small volcanic domes; and (4) scalloped margin domes ('ticks'). Steep

  5. Venus small volcano classification and description

    NASA Astrophysics Data System (ADS)

    Aubele, J. C.

    1993-03-01

    The high resolution and global coverage of the Magellan radar image data set allows detailed study of the smallest volcanoes on the planet. A modified classification scheme for volcanoes less than 20 km in diameter is shown and described. It is based on observations of all members of the 556 significant clusters or fields of small volcanoes located and described by this author during data collection for the Magellan Volcanic and Magmatic Feature Catalog. This global study of approximately 10 exp 4 volcanoes provides new information for refining small volcano classification based on individual characteristics. Total number of these volcanoes was estimated to be 10 exp 5 to 10 exp 6 planetwide based on pre-Magellan analysis of Venera 15/16, and during preparation of the global catalog, small volcanoes were identified individually or in clusters in every C1-MIDR mosaic of the Magellan data set. Basal diameter (based on 1000 measured edifices) generally ranges from 2 to 12 km with a mode of 34 km, and follows an exponential distribution similar to the size frequency distribution of seamounts as measured from GLORIA sonar images. This is a typical distribution for most size-limited natural phenomena unlike impact craters which follow a power law distribution and continue to infinitely increase in number with decreasing size. Using an exponential distribution calculated from measured small volcanoes selected globally at random, we can calculate total number possible given a minimum size. The paucity of edifice diameters less than 2 km may be due to inability to identify very small volcanic edifices in this data set; however, summit pits are recognizable at smaller diameters, and 2 km may represent a significant minimum diameter related to style of volcanic eruption. Guest, et al, discussed four general types of small volcanic edifices on Venus: (1) small lava shields; (2) small volcanic cones; (3) small volcanic domes; and (4) scalloped margin domes ('ticks'). Steep

  6. The origin of the Hawaiian Volcano Observatory

    SciTech Connect

    Dvorak, John

    2011-05-15

    I first stepped through the doorway of the Hawaiian Volcano Observatory in 1976, and I was impressed by what I saw: A dozen people working out of a stone-and-metal building perched at the edge of a high cliff with a spectacular view of a vast volcanic plain. Their primary purpose was to monitor the island's two active volcanoes, Kilauea and Mauna Loa. I joined them, working for six weeks as a volunteer and then, years later, as a staff scientist. That gave me several chances to ask how the observatory had started.

  7. In Brief: Russian volcano warnings reinstated

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2007-04-01

    The Kamchatka Volcanic Eruption Response Team (KVERT) is again issuing warnings for aviation during periods of activity by Kamchatkan volcanoes. KVERT had stopped issuing warnings on 1 March due to a loss of funding by the Federal Unitary Enterprise State Air Traffic Management Corporation of Russia (see Eos 88(12), 2007). The funding for this work has now resumed. KVERT is a collaborative project of scientists from the Russian Institute of Volcanology and Seismology, the Kamchatka Experimental and Methodical Seismological Department, and the Alaska Volcano Observatory.

  8. Volcán Las Navajas, a Pliocene-Pleistocene trachyte/peralkaline rhyolite volcano in the northwestern Mexican volcanic belt

    NASA Astrophysics Data System (ADS)

    Nelson, Stephen A.; Hegre, Joann

    1990-01-01

    Volcán Las Navajas, a Pliocene-Pleistocene volcano located in the northwestern portion of the Mexican volcanic belt, erupted lavas ranging in composition from alkali basalt through peralkaline rhyolite, and is the only volcano in mainland Mexico known to have erupted pantellerites. Las Navajas is located near the northwestern end of the Tepic-Zacoalco rift and covers a 200-m-thick pile of alkaline basaltic lavas, one of which has been dated at 4.3 Ma. The eruptive history of the volcano can be divided into three stages separated by episodes of caldera formation. During the first stage a broad shield volcano made up of alkali basalts, mugearites, benmoreites, trachytes, and peralkaline rhyolites was constructed. Eruption of a chemically zoned ash flow then caused collapse of the structure to form the first caldera. The second stage consisted of eruptions of glassy pantellerite lavas that partially filled the caldera and overflowed its walls. This stage ended about 200 000 years ago with the eruption of pumice falls and ash flows, which led to the collapse of the southern portion of the volcano to form the second caldera. During the third stage, two benmoreite cinder cones and a benmoreite lava flow were emplaced on the northwestern flank of the volcano. Finally, the calc-alkaline volcano Sanganguey was built on the southern flank of Las Lavajas. Alkaline volcanism continued in the area with eruptions of alkali basalt from cinder cones located along NW-trending fractures through the area. Although other mildly peralkaline rhyolites are found in the rift zones of western Mexico, only Las Navajas produced pantellerites. Greater volumes of basic alkaline magma have erupted in the Las Navajas region than in the other areas of peralkaline volcanism in Mexico, a factor which may be necessary to provide the initial volume of material and heat to drive the differentiation process to such extreme peralkaline compositions.

  9. Sakura-jima volcano in Japan as seen from STS-66 Atlantis

    NASA Technical Reports Server (NTRS)

    1994-01-01

    One of the world's most active volcanoes, Sakura-jima in southern-most Kyushu, Japan, erupts dozens of times a year. Volcanic eruptions are so much a part of of daily life in the city of Kagoshima (across the bay and west of Sakura-jima), that school children wear hard hats to school. This photo provides a nice clear view of Sakura-jima on a quiet day - only a plume of steam rises from the summit crater. The summit region is covered with gray ash from the frequent eruptions, and some of the rivers cutting down the mountain (especially the western drainages) appear to be filled with volcanic debris.

  10. Two-dimensional magnetotelluric and gravity models of the Tuzgle volcano zone (Jujuy province, Argentina)

    NASA Astrophysics Data System (ADS)

    Sainato, Claudia M.; Pomposiello, Maria C.

    1997-07-01

    The Tuzgle volcano (24 ° 03'S, 66 ° 29'W) is situated in the southern part of the South American Andean Altiplano (Puna). The region has several geothermal manifestations. A 2-D magnetotelluric model of resistivity distribution and a 3-D gravity anomaly of the area have been proposed. A highly conductive and low density body is probably associated with a magma chamber surrounded by free saline fluids with its top at about 8 km depth. The release of fluids might be caused by the chemical reactions generated at the subduction plate of Nazca in contact with the South American plate.

  11. Asymmetric deformation structure of lava spine in Unzen Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Miwa, T.; Okumura, S.; Matsushima, T.; Shimizu, H.

    2013-12-01

    Lava spine is commonly generated by effusive eruption of crystal-rich, dacitic-andesitic magmas. Especially, deformation rock on surface of lava spine has been related with processes of magma ascent, outgassing, and generation of volcanic earthquake (e.g., Cashman et al. 2008). To reveal the relationships and generation process of the spine, it is needed to understand a spatial distribution of the deformation rock. Here we show the spatial distribution of the deformation rock of lava spine in the Unzen volcano, Japan, to discuss the generation process of the spine. The lava spine in Unzen volcano is elongated in the E-W direction, showing a crest like shape with 150 long, 40 m wide and 50 m high. The lava spine is divided into following four parts: 1) Massive dacite part: Dense dacite with 30 m of maximum thickness, showing slickenside on the southern face; 2) Sheared dacite part: Flow band developed dacite with 1.0 m of maximum thickness; 3) Tuffisite part: Network of red colored vein develops in dacite with 0.5 m of maximum thickness; 4) Breccia part: Dacitic breccia with 10 m of maximum thickness. The Breccia part dominates in the northern part of the spine, and flops over Massive dacite part accross the Sheared dacite and Tuffisite parts. The slickenside on southern face of massive dacite demonstrates contact of solids. The slickenside breaks both of phenocryst and groundmass, demonstrating that the slickenside is formed after significant crystallization at the shallow conduit or on the ground surface. The lineation of the slickenside shows E-W direction with almost horizontal rake angle, which is consistent with the movement of the spine to an east before emplacement. Development of sub-vertical striation due to extrusion was observed on northern face of the spine (Hayashi, 1994). Therefore, we suggest that the spine just at extrusion consisted of Massive dacite, Sheared dacite, Tuffisite, Breccia, and Striation parts in the northern half of the spine. Such a

  12. Volcano shapes, entropies, and eruption probabilities

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust; Mohajeri, Nahid

    2014-05-01

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

  13. Mobile Response Team Saves Lives in Volcano Crises

    USGS Publications Warehouse

    Ewert, John W.; Miller, C. Dan; Hendley, James W., II; Stauffer, Peter H.

    1997-01-01

    The world's only volcano crisis response team, organized and operated by the USGS, can be quickly mobilized to assess and monitor hazards at volcanoes threatening to erupt. Since 1986, the team has responded to more than a dozen volcano crises as part of the Volcano Disaster Assistance Program (VDAP), a cooperative effort with the Office of Foreign Disaster Assistance of the U.S. Agency for International Development. The work of USGS scientists with VDAP has helped save countless lives, and the valuable lessons learned are being used to reduce risks from volcano hazards in the United States.

  14. Digital data set of volcano hazards for active Cascade Volcanos, Washington

    USGS Publications Warehouse

    Schilling, Steve P.

    1996-01-01

    Scientists at the Cascade Volcano Observatory have completed hazard assessments for the five active volcanos in Washington. The five studies included Mount Adams (Scott and others, 1995), Mount Baker (Gardner and others, 1995), Glacier Peak (Waitt and others, 1995), Mount Rainier (Hoblitt and others, 1995) and Mount St. Helens (Wolfe and Pierson, 1995). Twenty Geographic Information System (GIS) data sets have been created that represent the hazard information from the assessments. The twenty data sets have individual Open File part numbers and titles

  15. Detecting Volcano-Tectonic Earthquakes at the Tatun Volcano Group in Taiwan with Dense Arrays

    NASA Astrophysics Data System (ADS)

    Sun, W. F.; Lin, C. H.; Chang, W. Y.

    2015-12-01

    The Tatun Volcano Group (TVG) is located at the northernmost tip of the island of Taiwan. Although TVG have been erupted 0.1-0.2 Ma ago and are considered being extinct, some recent studies suggest that they are active or dormant volcanos. We perform a systematic detection of volcano-tectonic earthquakes beneath TVG using three dense, small-aperture seismic arrays, which were deployed for six months in 2012. We use broadband frequency-wavenumber beam forming and moving-window grid-search methods to compute array parameters for all nearly continuous data and identify volcano-tectonic earthquakes. We detect much more events than that listed in the TVG volcano-tectonic earthquake catalog, about 50 events per month. Our results suggest that dense array techniques are capable of capturing detailed spatiotemporal evolution of volcano-tectonic earthquake behaviours at TVG, and also help to better understand the source mechanism of the brittle, uppermost part of the crust to the combined effect of the local hydrothermal fluid pressure and the regional stress field in the volcanic environment.

  16. Multidisciplinary Monitoring Experiments at Kawah Ijen Volcano

    NASA Astrophysics Data System (ADS)

    Gunawan, Hendra; Pallister, John; Caudron, Corentin

    2014-12-01

    "Wet volcanoes" with crater lakes and extensive hydrothermal systems pose challenges for monitoring and forecasting eruptions. That's because their lakes and hydrothermal systems serve as reservoirs for magmatic heat and fluid emissions, filtering and delaying the surface expressions of magmatic unrest.

  17. Biological Studies on a Live Volcano.

    ERIC Educational Resources Information Center

    Zipko, Stephen J.

    1992-01-01

    Describes scientific research on an Earthwatch expedition to study Arenal, one of the world's most active volcanoes, in north central Costa Rica. The purpose of the two-week project was to monitor and understand the past and ongoing development of a small, geologically young, highly active stratovolcano in a tropical, high-rainfall environment.…

  18. Preliminary radon measurements at Villarrica volcano, Chile

    NASA Astrophysics Data System (ADS)

    Cigolini, C.; Laiolo, M.; Coppola, D.; Ulivieri, G.

    2013-10-01

    We report data from a radon survey conducted at Villarrica volcano. Measurements have been obtained at selected sites by E-PERM® electrets and two automatic stations utilizing DOSEman detectors (SARAD Gmbh). Mean values for Villarrica are 1600 (±1150) Bq/m3 are similar to values recorded at Cerro Negro and Arenal in Central America. Moderately higher emissions, at measurement sites, were recorded on the NNW sector of the volcano and the summit, ranging from 1800 to 2400 Bq/m3. These measurements indicate that this area could potentially be a zone of flank weakness. In addition, the highest radon activities, up to 4600 Bq/m3, were measured at a station located near the intersection of the Liquiñe-Ofqui Fault Zone with the Gastre Fault Zone. To date, the Villarrica radon measurements reported here are, together with those collected at Galeras (Colombia), the sole radon data reported from South American volcanoes. This research may contribute to improving future geochemical monitoring and volcano surveillance.

  19. Different types of small volcanos on Venus

    NASA Technical Reports Server (NTRS)

    Slyuta, E. N.; Shalimov, I. V.; Nikishin, A. M.

    1992-01-01

    One of the studies of volcanic activity on Venus is the comparison of that with the analogous volcanic activity on Earth. The preliminary report of such a comparison and description of a small cluster of small venusian volcanos is represented in detail in this paper.

  20. Abrupt shift in δ18O values at Medicine Lake volcano (California, USA)

    USGS Publications Warehouse

    Donnelly-Nolan, J. M.

    1998-01-01

     Oxygen-isotope analyses of lavas from Medicine Lake volcano (MLV), in the southern Cascade Range, indicate a significant change in δ18O in Holocene time. In the Pleistocene, basaltic lavas with <52% SiO2 averaged +5.9‰, intermediate lavas averaged +5.7‰, and silicic lavas (≥63.0%SiO2) averaged +5.6‰. No analyzed Pleistocene rhyolites or dacites have values greater than +6.3‰. In post-glacial time, basalts were similar at +5.7‰ to those erupted in the Pleistocene, but intermediate lavas average +6.8‰ and silicic lavas +7.4‰ with some values as high as +8.5‰. The results indicate a change in the magmatic system supplying the volcano. During the Pleistocene, silicic lavas resulted either from melting of low-18O crust or from fractionation combined with assimilation of very-low-18O crustal material such as hydrothermally altered rocks similar to those found in drill holes under the center of the volcano. By contrast, Holocene silicic lavas were produced by assimilation and/or wholesale melting of high-18O crustal material such as that represented by inclusions of granite in lavas on the upper flanks of MLV. This sudden shift in assimilant indicates a fundamental change in the magmatic system. Magmas are apparently ponding in the crust at a very different level than in Pleistocene time.

  1. Seismicity at Baru Volcano, Western Panama, Panama

    NASA Astrophysics Data System (ADS)

    Camacho, E.; Novelo-Casanova, D. A.; Tapia, A.; Rodriguez, A.

    2008-12-01

    The Baru volcano in Western Panama (8.808°N, 82.543°W) is a 3,475 m high strato volcano that lies at about 50 km from the Costa Rican border. The last major eruptive event at this volcano occurred c.1550 AD and no further eruptive activity from that time is known. Since the 1930´s, approximately every 30 years a series of seismic swarms take place in the surroundings of the volcanic edifice. Theses swarms last several weeks alarming the population who lives near the volcano. The last of these episodes occurred on May 2006 and lasted one and a half months. More than 20,000 people live adjacent to the volcano and any future eruption has the potential to be very dangerous. In June 2007, a digital seismic monitoring network of ten stations, linked via internet, was installed around the volcano in a collaborative project between the University of Panama and the Panamanian Government. The seismic data acquisition at the sites is performed using LINUX-SEISLOG and the events are recorded by four servers at different locations using the Earth Worm system. In this work we analyze the characteristics of the volcano seismicity recorded from May 4th, 2006 to July 31st, 2008 by at least 4 stations and located at about 15 km from the summit. To determine the seismic parameters, we tested several crustal velocity models and used the seismic analysis software package SEISAN. Our final velocity model was determined using seismic data for the first four km obtained from a temporal seismic network deployed in 1981 by the British Geological Survey (BGS) as part of geothermal studies conducted at Cerro Pando, Western Panama Highlands. Our results indicate that all the events recorded in the quadrant 8.6-9.0°N and 82.2-82.7°W are located in the depth range of 0.1 to 8 km. Cross sections show vertical alignments of hypocenters below the summit although most of the seismicity is concentrated in its eastern flank reaching the town of Boquete. All the calculated focal mechanisms are of

  2. Hazard maps of Colima volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Escudero Ayala, C. R.

    2011-12-01

    Colima volcano, also known as Volcan de Fuego (19° 30.696 N, 103° 37.026 W), is located on the border between the states of Jalisco and Colima and is the most active volcano in Mexico. Began its current eruptive process in February 1991, in February 10, 1999 the biggest explosion since 1913 occurred at the summit dome. The activity during the 2001-2005 period was the most intense, but did not exceed VEI 3. The activity resulted in the formation of domes and their destruction after explosive events. The explosions originated eruptive columns, reaching attitudes between 4,500 and 9,000 m.a.s.l., further pyroclastic flows reaching distances up to 3.5 km from the crater. During the explosive events ash emissions were generated in all directions reaching distances up to 100 km, slightly affected nearby villages as Tuxpan, Tonila, Zapotlán, Cuauhtemoc, Comala, Zapotitlan de Vadillo and Toliman. During the 2005 this volcano has had an intense effusive-explosive activity, similar to the one that took place during the period of 1890 through 1900. Intense pre-plinian eruption in January 20, 1913, generated little economic losses in the lower parts of the volcano due to low population density and low socio-economic activities at the time. Shows the updating of the volcanic hazard maps published in 2001, where we identify whit SPOT satellite imagery and Google Earth, change in the land use on the slope of volcano, the expansion of the agricultural frontier on the east and southeast sides of the Colima volcano, the population inhabiting the area is approximately 517,000 people, and growing at an annual rate of 4.77%, also the region that has shown an increased in the vulnerability for the development of economic activities, supported by the construction of highways, natural gas pipelines and electrical infrastructure that connect to the Port of Manzanillo to Guadalajara city. The update the hazard maps are: a) Exclusion areas and moderate hazard for explosive events

  3. The Anatahan volcano-monitoring system

    NASA Astrophysics Data System (ADS)

    Marso, J. N.; Lockhart, A. B.; White, R. A.; Koyanagi, S. K.; Trusdell, F. A.; Camacho, J. T.; Chong, R.

    2003-12-01

    A real-time 24/7 Anatahan volcano-monitoring and eruption detection system is now operational. There had been no real-time seismic monitoring on Anatahan during the May 10, 2003 eruption because the single telemetered seismic station on Anatahan Island had failed. On May 25, staff from the Emergency Management Office (EMO) of the Commonwealth of the Northern Mariana Islands and the U. S. Geological Survey (USGS) established a replacement telemetered seismic station on Anatahan whose data were recorded on a drum recorder at the EMO on Saipan, 130 km to the south by June 5. In late June EMO and USGS staff installed a Glowworm seismic data acquisition system (Marso et al, 2003) at EMO and hardened the Anatahan telemetry links. The Glowworm system collects the telemetered seismic data from Anatahan and Saipan, places graphical display products on a webpage, and exports the seismic waveform data in real time to Glowworm systems at Hawaii Volcano Observatory and Cascades Volcano Observatory (CVO). In early July, a back-up telemetered seismic station was placed on Sarigan Island 40 km north of Anatahan, transmitting directly to the EMO on Saipan. Because there is currently no population on the island, at this time the principal hazard presented by Anatahan volcano would be air traffic disruption caused by possible erupted ash. The aircraft/ash hazard requires a monitoring program that focuses on eruption detection. The USGS currently provides 24/7 monitoring of Anatahan with a rotational seismic duty officer who carries a Pocket PC-cell phone combination that receives SMS text messages from the CVO Glowworm system when it detects large seismic signals. Upon receiving an SMS text message notification from the CVO Glowworm, the seismic duty officer can use the Pocket PC - cell phone to view a graphic of the seismic traces on the EMO Glowworm's webpage to determine if the seismic signal is eruption related. There have been no further eruptions since the monitoring system was

  4. A thick lens of fresh groundwater in the southern Lihue Basin, Kauai, Hawaii, USA

    USGS Publications Warehouse

    Izuka, S.K.; Gingerich, S.B.

    2003-01-01

    A thick lens of fresh groundwater exists in a large region of low permeability in the southern Lihue Basin, Kauai, Hawaii, USA. The conventional conceptual model for groundwater occurence in Hawaii and other shield-volcano islands does not account for such a thick freshwater lens. In the conventional conceptual model, the lava-flow accumulations of which most shield volcanoes are built form large regions of relatively high permeability and thin freshwater lenses. In the southern Lihue Basin, basin-filling lavas and sediments form a large region of low regional hydraulic conductivity, which, in the moist climate of the basin, is saturated nearly to the land surface and water tables are hundreds of meters above sea level within a few kilometers from the coast. Such high water levels in shield-volcano islands were previously thought to exist only under perched or dike-impounded conditions, but in the southern Lihue Basin, high water levels exist in an apparently dike-free, fully saturated aquifer. A new conceptual model of groundwater occurrence in shield-volcano islands is needed to explain conditions in the southern Lihue Basin.

  5. Magma Piracy in the Southern Mariana Backarc

    NASA Astrophysics Data System (ADS)

    Becker, N. C.; Fryer, P.; Martinez, F.; Stern, R. J.; Bloomer, S. H.

    2001-12-01

    Since 1997 the southern Mariana convergent margin system has been mapped with Hydrosweep, MR-1, and SeaBeam swath sonar systems on five cruises resulting in 168,500 km2 of bathymetry data and 186,800 km2 of sidescan data, revealing anomalous processes relative to the rest of the Mariana region. Most of the Mariana Arc is characterized by arc volcanism dominated by large, central volcanoes located at the boundary between a backarc basin with slow-spreading ridge morphology and a nonaccretionary forearc composed of Eocene volcanic arc rocks But southwest of Tracey Seamount, the southernmost large central arc volcano, the character of the arc and backarc changes dramatically. The arc volcanoes become small or nonexistent, but those that do occur lie along relict spreading fabric within the backarc basin. Furthermore, the spreading center appears to have an inflated, fast-spreading morphology, including dueling propagator fabric, and this southern backarc basin forms a shallow plateau overall. The spreading center then becomes less well-defined west of 143oE, and the volcanism appears to cease altogether west of 142oE in an area of amagmatic rifting, an observation supported by earthquake focal mechanisms and magnetics. The inflated morphology of the spreading axis, along with the absence or reduced size of nearby arc volcanoes suggests that arc magmas have been entrained into the backarc-spreading magmatic system. This "magma piracy" would result in arc magma being erupted at the backarc spreading center, therefore the backarc crust would be formed in part from arc magmas. Dredge samples from along the active ridge show compositions consistent with this suggestion. We suggest that this magma piracy has dominated the southern backarc basin for at least the last 3 m.y. since the robust spreading began. We suggest that the apparently higher magma production rate and the hybridized crust could account for the shallowness of the basin, as the more evolved arc-lavas would

  6. Mantle CO2 degassing at Mt. Vulture volcano (Italy): Relationship between CO2 outgassing of volcanoes and the time of their last eruption

    NASA Astrophysics Data System (ADS)

    Caracausi, Antonio; Paternoster, Michele; Nuccio, Pasquale Mario

    2015-02-01

    tectonic discontinuities that controlled the magma upwelling during the most recent volcanic activity are still the main active degassing structures. The new estimate of CO2 budget in the Mt. Vulture area, together with literature data on CO2 budget from historically active and inactive Italian volcanoes, suggests a power-law functional relationship between the age of the most recent volcanic eruption and both total discharged CO2 (R2 = 0.73) and volcano size-normalized CO2 flux (R2 = 0.66). This relation is also valid by using data from worldwide volcanoes highlighting that deep degassing can occur over very long time too. In turn, the highlighted relation provides also an important tool to better evaluate the state of activity of a volcano, whose last activity occurred far in time. Finally, our study highlights that in the southern Apennines, an active degassing of mantle-derived volatiles (i.e., He, CO2) occurs indiscriminately from west to east. This is in contrast to the central-northern Apennine, which is characterized by a crustal radiogenic volatile contribution, which increases eastward, coupled to a decrease in deep CO2 flux. This difference between the two regions is probably due to lithospheric tears which control the upwelling of mantle melts, their degassing and the transport of volatiles through the crust.

  7. New Isopach Maps of Holocene Rhyolitic Tephras at Medicine Lake Volcano, Northern California

    NASA Astrophysics Data System (ADS)

    Miller, C.; Ramsey, D. W.; Ewert, J. W.

    2008-12-01

    Medicine Lake Volcano, located in the southern Cascades ~55 km east-northeast of Mount Shasta, is a large rear-arc, shield-shaped volcano with an eruptive history spanning nearly 500 ka (Donnelly-Nolan, et al., 2008). The most recent eruptions at Medicine Lake Volcano are the late Holocene explosive to effusive events at Glass Mountain (~950 yr) and Little Glass Mountain (~1000 yr), which began as sub- Plinian to Plinian eruptions of rhyolite pumice from fissure vents (Heiken, 1978), and culminated in the rhyolite-dacite of Glass Mountain and the rhyolite of Little Glass Mountain. Vents for these eruptions are located 15 km apart on opposite sides of the summit caldera of Medicine Lake Volcano. Glass Mountain erupted from a 5-km-long fissure on the east side and Little Glass Mountain from an 8-km-long fissure on the west side of the volcano. New isopach maps of tephra deposits from these eruptions are based on more extensive fieldwork and on a different interpretation of Little Glass Mountain tephras than previous work. The maps show a strong northeast-southwest trend of the Little Glass Mountain tephras as previously shown by Fisher (1964) and by Heiken (1978), extending in the direction of Mount Shasta, where D. Miller found individual lapilli from the Little Glass Mountain eruption. Tephras from Glass Mountain are not deposited along a single strong trend, but rather are found in lobes extending from the fissure vents to the west, north, and northeast. More than 2 m of Little Glass Mountain tephra was deposited proximal to its vents, although the deposit thins quickly to less than 50 cm within 2 km perpendicular to trend and within 7 km along trend. The maximum observed thickness of Glass Mountain tephra is between 7-8 m proximal to its vents, thinning to less than 50 cm within 7 km distance from the vents. As rhyolite eruptions in the Cascade Range are quite rare, mapping the thickness, extent, and character of these tephra deposits to better comprehend the

  8. Intense Seismic Activity at Chiles and Cerro Negro Volcanoes on the Colombia-Ecuador Border

    NASA Astrophysics Data System (ADS)

    Torres, R. A.; Cadena, O.; Gomez, D.; Ruiz, M. C.; Prejean, S. G.; Lyons, J. J.; White, R. A.

    2015-12-01

    The region of Chiles and Cerro Negro volcanoes, located on the Colombian-Ecuadorian border, has experienced an ongoing seismic swarm beginning in Aug. 2013. Based on concern for local residents and authorities, a cooperative broadband monitoring network was installed by the Servicio Geológico Colombiano in Colombia and the Instituto Geofísico of the Escuela Politécnica Nacional in Ecuador. Since November 2013 more than 538,000 earthquakes were recorded; although since May 2015 the seismicity has decreased significantly to an average of 70 events per day. Three large earthquake swarms with increasing energy occurred in Aug.-Oct. 2013, March-May 2014, and Sept.-Dec. 2014. By the end of 2014, roughly 400 earthquakes greater than M 3 had occurred with a maximum rate of 8000 earthquakes per day. The largest earthquake was a 5.6 ML on Oct. 20, 2014. This event produced an InSAR coseismic deformation of ~23 cm (S. Ebmeier, personal communication). Most events are typical brittle failure volcano-tectonic (VT) earthquakes that are located in a cluster beneath the southern flank of Chiles volcano, with depths between 1.5 and 10 km. Although the great majority of earthquakes are VT, some low-frequency (LF, ~0.5 Hz) and very-low-frequency (VLF) events have occurred. Particle motion analysis suggests that the VLF source migrated with time. While a VLF on Oct. 15, 2014 was located south of Chiles volcano, near the InSAR source, the VLF registered on Feb. 14, 2015 was likely located very close to Chiles Volcano. We infer that magma intrusion and resulting fluid exsolution at depths greater than 5 km are driving seismicity in the Chiles-Cerro Negro region. However earthquakes are failing in a manner consistent with regional tectonics. Relative relocations reveal a structure consistent with mapped regional faults. Thus seismicity is likely controlled by an interaction of magmatic and tectonic processes. Because the regional stress field is highly compressional and the volcanoes

  9. Monitoring Cumbre Vieja volcano (La Palma, Canary Islands) from 2001 to 2015 by means of diffuse CO2 degassing

    NASA Astrophysics Data System (ADS)

    Padrón, Eleazar; Berry, Hannah; Robinson, Helen; Rodríguez, Fátima; Dionis, Samara; Pérez, Nemesio M.

    2016-04-01

    La Palma Island, the fifth longest (706 km2) and second highest (2,423 m asl) of the Canary Islands, is located at the northwestern end of the archipelago. Subaerial volcanic activity on La Palma started ˜2.0 My ago and has taken place exclusively at the southern part of the island in the last 123 ka, where Cumbre Vieja volcano, the most active basaltic volcano in the Canaries, has been constructed. Cumbre Vieja volcano, which has been likened to a Hawaiian-style rift zone, includes a main north-south rift zone 20 km long and up to 1,950 m in elevation, and covers 220 km2 with vents located also at the northwest and northeast. Nowadays, there are no visible gas emissions from fumaroles or hot springs at Cumbre Vieja, but large amounts of CO2 are released as diffuse soil emanations from the flanks of the volcano. Recent studies have shown that enhanced endogenous contributions of deep-seated CO2 might have been responsible for higher diffuse CO2 emission values (Padrón et al., 2015). We report here the latest results of the diffuse CO2 efflux survey at Cumbre Vieja volcano. The CO2 efflux measurements were taken using the accumulation chamber method in the summer period of 2015 to constrain the total CO2 output from the studied area and to evaluate occasional CO2 efflux surveys as a volcanic surveillance tool for Cumbre Vieja. Soil CO2 efflux values ranged from non-detectable up to 360 g m‑2 d‑1. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. The spatial distribution of diffuse CO2 emission values did not seem to be controlled by the main structural features of the volcano since the highest values were measured in the southern part. The total CO2 output released to the atmosphere in a diffuse way has been estimated at 359 t d‑1, which represents one of the lowest emission rates reported since 1997 (Padrón et al., 2015). Our results confirm the volcanic quiescence state of Cumbre Vieja, but reassert

  10. The geological evolution of Merapi volcano, Central Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Gertisser, Ralf; Charbonnier, Sylvain J.; Keller, Jörg; Quidelleur, Xavier

    2012-07-01

    Merapi is an almost persistently active basalt to basaltic andesite volcanic complex in Central Java (Indonesia) and often referred to as the type volcano for small-volume pyroclastic flows generated by gravitational lava dome failures (Merapi-type nuées ardentes). Stratigraphic field data, published and new radiocarbon ages in conjunction with a new set of 40K-40Ar and 40Ar-39Ar ages, and whole-rock geochemical data allow a reassessment of the geological and geochemical evolution of the volcanic complex. An adapted version of the published geological map of Merapi [(Wirakusumah et al. 1989), Peta Geologi Gunungapi Merapi, Jawa Tengah (Geologic map of Merapi volcano, Central Java), 1:50,000] is presented, in which eight main volcano stratigraphic units are distinguished, linked to three main evolutionary stages of the volcanic complex—Proto-Merapi, Old Merapi and New Merapi. Construction of the Merapi volcanic complex began after 170 ka. The two earliest (Proto-Merapi) volcanic edifices, Gunung Bibi (109 ± 60 ka), a small basaltic andesite volcanic structure on Merapi's north-east flank, and Gunung Turgo and Gunung Plawangan (138 ± 3 ka; 135 ± 3 ka), two basaltic hills in the southern sector of the volcano, predate the Merapi cone sensu stricto. Old Merapi started to grow at ~30 ka, building a stratovolcano of basaltic andesite lavas and intercalated pyroclastic rocks. This older Merapi edifice was destroyed by one or, possibly, several flank failures, the latest of which occurred after 4.8 ± 1.5 ka and marks the end of the Old Merapi stage. The construction of the recent Merapi cone (New Merapi) began afterwards. Mostly basaltic andesite pyroclastic and epiclastic deposits of both Old and New Merapi (<11,792 ± 90 14C years BP) cover the lower flanks of the edifice. A shift from medium-K to high-K character of the eruptive products occurred at ~1,900 14C years BP, with all younger products having high-K affinity. The radiocarbon record points towards an

  11. Geochemistry of natural gases from mud volcanoes and surface gas seeps in NW-Columbia

    SciTech Connect

    Beeunas, M.A. ); Schoell, M. ); Beroiz, C. )

    1991-03-01

    Mud volcanoes and natural gas seeps are common in the southwest-northeast-trending Sinu Atlantico basin (SAB) and San Jacinto Fold Belt (SJFB) of NW-Colombia. The structural subunits are part of a highly complex active continental margin where the sediments become increasingly younger to the west from Late Cretaceous to Early Tertiary in the SJFB to Late Tertiary in the SAB. Some of the mud volcanoes are permanently active and form huge structures and are often aligned along major faults. Both seep and mud volcano gases are with low C{sub 2}-C{sub 4} and CO{sub 2} contents. Carbon and hydrogen isotope concentrations allow the subdivision into four groups of gas. These gases can be divided into four genetic based on their carbon and hydrocarbon isotope compositions. The isotopic variability of the different groups attests to the fact that very different gas-forming processes are or have been operating in the subsurface ranging from low-temperature thermogenesis. The various groups show, with few exceptions, a distinct regional distribution: Mud volcanoes and seeps with bacterial gases are restricted to the southern part of the SAB where the greatest thickness of young sediments is observed; gases of mixed thermogenic and bacterial origin are found in the coastal areas of the northern SAB; gases of thermogenic origin are predominantly observed in the SJFB; the thermogenic gases of Group 3 are restricted to two locations in the north of the SJFB. This regional association of genetic gas types with specific geotectonic units reflects different thermal histories of the respective tectonic areas and allowed the authors to delineate prospective areas for oil in NW-Colombia.

  12. Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)

    NASA Astrophysics Data System (ADS)

    Baudouin, Céline; Parat, Fleurice; Denis, Carole M. M.; Mangasini, Fredrik

    2016-07-01

    North Tanzanian Divergence is the first stage of continental break-up of East African Rift (<6 Ma) and is one of the most concentrated areas of carbonatite magmatism on Earth, with singular Oldoinyo Lengai and Kerimasi volcanoes. Hanang volcano is the southernmost volcano in the North Tanzanian Divergence and the earliest stage of rift initiation. Hanang volcano erupted silica-undersaturated alkaline lavas with zoned clinopyroxene, nepheline, andradite-schorlomite, titanite, apatite, and pyrrhotite. Lavas are low MgO-nephelinite with low Mg# and high silica content (Mg# = 22.4-35.2, SiO2 = 44.2-46.7 wt%, respectively), high incompatible element concentrations (e.g. REE, Ba, Sr) and display Nb-Ta fractionation (Nb/Ta = 36-61). Major elements of whole rock are consistent with magmatic differentiation by fractional crystallization from a parental melt with melilititic composition. Although fractional crystallization occurred at 9-12 km and can be considered as an important process leading to nephelinite magma, the complex zonation of cpx (e.g. abrupt change of Mg#, Nb/Ta, and H2O) and trace element patterns of nephelinites recorded magmatic differentiation involving open system with carbonate-silicate immiscibility and primary melilititic melt replenishment. The low water content of clinopyroxene (3-25 ppm wt. H2O) indicates that at least 0.3 wt% H2O was present at depth during carbonate-rich nephelinite crystallization at 340-640 MPa and 1050-1100 °C. Mg-poor nephelinites from Hanang represent an early stage of the evolution path towards carbonatitic magmatism as observed in Oldoinyo Lengai. Paragenesis and geochemistry of Hanang nephelinites require the presence of CO2-rich melilititic liquid in the southern part of North Tanzanian Divergence and carbonate-rich melt percolations after deep partial melting of CO2-rich oxidized mantle source.

  13. Long-period seismic events with strikingly regular temporal patterns on Katla volcano's south flank (Iceland)

    NASA Astrophysics Data System (ADS)

    Sgattoni, Giulia; Jeddi, Zeinab; Gudmundsson, Ólafur; Einarsson, Páll; Tryggvason, Ari; Lund, Björn; Lucchi, Federico

    2016-09-01

    Katla is a threatening volcano in Iceland, partly covered by the Mýrdalsjökull ice cap. The volcano has a large caldera with several active geothermal areas. A peculiar cluster of long-period seismic events started on Katla's south flank in July 2011, during an unrest episode in the caldera that culminated in a glacier outburst. The seismic events were tightly clustered at shallow depth in the Gvendarfell area, 4 km south of the caldera, under a small glacier stream at the southern margin of Mýrdalsjökull. No seismic events were known to have occurred in this area before. The most striking feature of this seismic cluster is its temporal pattern, characterized by regular intervals between repeating seismic events, modulated by a seasonal variation. Remarkable is also the stability of both the time and waveform features over a long time period, around 3.5 years. We have not found any comparable examples in the literature. Both volcanic and glacial processes can produce similar waveforms and therefore have to be considered as potential seismic sources. Discerning between these two causes is critical for monitoring glacier-clad volcanoes and has been controversial at Katla. For this new seismic cluster on the south flank, we regard volcano-related processes as more likely than glacial ones for the following reasons: 1) the seismic activity started during an unrest episode involving sudden melting of the glacier and a jökulhlaup; 2) the glacier stream is small and stagnant; 3) the seismicity remains regular and stable for years; 4) there is no apparent correlation with short-term weather changes, such as rainstorms. We suggest that a small, shallow hydrothermal system was activated on Katla's south flank in 2011, either by a minor magmatic injection or by changes of permeability in a local crack system.

  14. A low-relief shield volcano origin for the South Kaua`i Swell

    NASA Astrophysics Data System (ADS)

    Ito, Garrett; Garcia, Michael O.; Smith, John R.; Taylor, Brian; Flinders, Ashton; Jicha, Brian; Yamasaki, Seiko; Weis, Dominique; Swinnard, Lisa; Blay, Chuck

    2013-07-01

    The South Kaua`i Swell (SKS) is a 110 km x 80 km ovoid bathymetric feature that stands >2 km high and abuts the southern flank of the island of Kaua`i. The origin of the SKS was investigated using multibeam bathymetry and acoustic backscatter, gravity data, radiometric ages, and geochemistry of rock samples. Most of the SKS rock samples are tholeiitic in composition with ages of 3.9-5.4 Ma indicating they were derived from shield volcanism. The ages and compositions of the SKS rocks partially overlap with those of the nearby Ni`ihau, Kaua`i and West Ka`ena volcano complexes. The SKS was originally described as a landslide; however, this interpretation is problematic given the ovoid shape of SKS, its relatively smooth, flat-to-convex surface, and the lack of an obvious source region that could accommodate what would be one of Earth's most voluminous (6 x 103 km3) landslides. The morphology, size, and the surrounding gravity anomaly are more consistent with the SKS being a low-relief shield volcano, which was partially covered with a small volume of landside debris from south Kaua`i and later with some secondary volcanic seamounts. A shield origin would imply that Hawaiian and possibly other hotspot shield volcanoes can take on a wider variety of forms than is commonly thought, ranging from tall island-building shields, to smaller edifices such as Ka`ena Ridge and Mahukona, to even lower-relief volcanoes represented by the SKS and possibly the South West O`ahu Volcanic Field.

  15. Some regularity in the process of re-awakening of andesite and dacite volcanoes: specific features of the 1982 El Chichón volcano, México reactivation

    NASA Astrophysics Data System (ADS)

    Zobin, Vyacheslav M.; Jiménez, Zenón

    2008-08-01

    El Chichón volcano is an andesite stratovolcano in southern México. It erupted in March 1982, after about 550 years of quiescence. The 1982 eruption of El Chichón has not been followed by the growth of a lava dome within the newly formed crater. This is rather anomalous since the construction of a new dome after the destruction of an old one is a common process during the eruptions at andesite and dacite volcanoes. To discuss this anomalous aspect of the El Chichón eruption, some regularity in the process of re-awakening of dormant (here defined as a period of quiescence of more than 100 years) andesite and dacite volcanoes are studied based on the seismic activity recorded at the volcanoes Bezymianny, Mount St. Helens, El Chichón, Unzen, Pinatubo and Soufrière Hills. Three stages were identified in the re-awakening activity of these volcanoes: (1) preliminary seismic activity, leading up to the first phreatic explosion; (2) activity between the first and the largest explosions; (3) post-explosion dome-building process. The eruptions were divided into two groups: low-VEI (Volcanic Explosivity Index) and the long duration stage-1 events (Unzen, 1991 and Soufrière Hills volcano, 1995) and high-VEI and the short duration stage-1 events (Bezymianny, 1956; Mount St. Helens, 1980; El Chichón, 1982 and Pinatubo, 1992). The comparative analysis of the seismo-eruptive activity of two eruptions of the second group, the 1980 of Mt. St. Helens and the 1982 of El Chichón, produced an explanation the absence of new dome building during the 1982 eruption of El Chichón volcano. It may be explained in terms of the unusually rapid emission of gas and water from the magmatic and hydrothermal system beneath the volcano during a relatively short sequence of large explosions that could have sharply increased the viscosity of the magma making impossible its exit to the surface.

  16. Space Radar Image of Colombian Volcano

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a radar image of a little known volcano in northern Colombia. The image was acquired on orbit 80 of space shuttle Endeavour on April 14, 1994, by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). The volcano near the center of the image is located at 5.6 degrees north latitude, 75.0 degrees west longitude, about 100 kilometers (65 miles) southeast of Medellin, Colombia. The conspicuous dark spot is a lake at the bottom of an approximately 3-kilometer-wide (1.9-mile) volcanic collapse depression or caldera. A cone-shaped peak on the bottom left (northeast rim) of the caldera appears to have been the source for a flow of material into the caldera. This is the northern-most known volcano in South America and because of its youthful appearance, should be considered dormant rather than extinct. The volcano's existence confirms a fracture zone proposed in 1985 as the northern boundary of volcanism in the Andes. The SIR-C/X-SAR image reveals another, older caldera further south in Colombia, along another proposed fracture zone. Although relatively conspicuous, these volcanoes have escaped widespread recognition because of frequent cloud cover that hinders remote sensing imaging in visible wavelengths. Four separate volcanoes in the Northern Andes nations ofColombia and Ecuador have been active during the last 10 years, killing more than 25,000 people, including scientists who were monitoring the volcanic activity. Detection and monitoring of volcanoes from space provides a safe way to investigate volcanism. The recognition of previously unknown volcanoes is important for hazard evaluations because a number of major eruptions this century have occurred at mountains that were not previously recognized as volcanoes. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of

  17. Trace metal suites in Antarctic pre-industrial ice are consistent with emissions from quiescent degassing of volcanoes worldwide

    USGS Publications Warehouse

    Matsumoto, A.; Hinkley, T.K.

    2001-01-01

    Trace metals are more abundant in atmospheric load and deposition material than can be due to rock and soil dusts and ocean salt. In pre-industrial ice from coastal west Antarctica, dust and salt account for only a few percent of the lead, cadmium, and indium that is present in most samples, less than half in any sample. For these trace metals, the deposition rate to the pre-industrial ice is approximately matched by the output rate to the atmosphere by quiescent (non-explosive) degassing of volcanoes worldwide, according to a new estimate. The basis of the match is the masses and proportions of the metals, and the proportions of Pb isotopes, in ice and in volcano emissions. The isotopic compositions of Pb in ice are similar to those of a suite of ocean island volcanoes, mostly in the southern hemisphere. The natural baseline values for pre-industrial atmospheric deposition fluxes of trace metal suites at Taylor Dome, and the worldwide quiescent volcano emissions fluxes to which they are linked, constitute a reasonably well-constrained baseline component for deposition fluxes of metals in modern times. ?? 2001 Elsevier Science B.V. All rights reserved.

  18. Trace metal suites in Antarctic pre-industrial ice are consistent with emissions from quiescent degassing of volcanoes worldwide

    NASA Astrophysics Data System (ADS)

    Matsumoto, Akikazu; Hinkley, Todd K.

    2001-03-01

    Trace metals are more abundant in atmospheric load and deposition material than can be due to rock and soil dusts and ocean salt. In pre-industrial ice from coastal west Antarctica, dust and salt account for only a few percent of the lead, cadmium, and indium that is present in most samples, less than half in any sample. For these trace metals, the deposition rate to the pre-industrial ice is approximately matched by the output rate to the atmosphere by quiescent (non-explosive) degassing of volcanoes worldwide, according to a new estimate. The basis of the match is the masses and proportions of the metals, and the proportions of Pb isotopes, in ice and in volcano emissions. The isotopic compositions of Pb in ice are similar to those of a suite of ocean island volcanoes, mostly in the southern hemisphere. The natural baseline values for pre-industrial atmospheric deposition fluxes of trace metal suites at Taylor Dome, and the worldwide quiescent volcano emissions fluxes to which they are linked, constitute a reasonably well-constrained baseline component for deposition fluxes of metals in modern times.

  19. Petrogenesis of a voluminous Quaternary adakitic volcano: the case of Baru volcano

    NASA Astrophysics Data System (ADS)

    Hidalgo, Paulo J.; Rooney, Tyrone O.

    2014-09-01

    The origin of adakite magmas remains controversial because initially the term adakite had petrogenetic significance implying an origin by direct melting of the eclogitized subducting oceanic crust. Many models have been produced for their origin, and until now there has not been a straightforward method to discriminate between these models in a given adakite suite. Here, we use detailed chronological and geochemical studies of selected adakitic edifices that allows for the determination of the magmatic output rate parameter (Qe), which has been correlated with the rates of magma generation deep within subduction zones. By providing temporal and eruption rate estimates, we provide constraints on the possible petrogenetic processes involved in the generation of adakite-like signatures. Adakite magmas derived from the melting of the subducting slab should be volumetrically insignificant when compared to the adakite-like magmas produced by typical arc magma generation processes. In this study, we use this observation and the extraordinary stratigraphic exposure from Miocene to present in an adakitic volcano in Panama and to study the temporal and chemical variation in erupted magmas to estimate rates of magma generation. Detailed chemical and geochronological analyses of Baru volcano indicate that the volcanic edifice was constructed in its entirety during the Quaternary and magmas display adakite-like features such as steep rare earth elements patterns, pronounced depletions in the heavy rare earth elements, low Y, high Sr, and high Sr/Y. The magmatic output rates (Qe) that we have calculated show that compared to other typical adakitic volcanoes, most of the volcanic edifice of Baru volcano was constructed extremely rapidly (<~213 k.a.) and in time frames that are similar to typical arc volcanoes. The observed chemical and mineralogical variation, coupled with the high magma production rates, indicate that Baru volcano is more representative of a typical arc volcano

  20. Common processes at unique volcanoes - a volcanological conundrum

    NASA Astrophysics Data System (ADS)

    Cashman, Katharine; Biggs, Juliet

    2014-11-01

    An emerging challenge in modern volcanology is the apparent contradiction between the perception that every volcano is unique, and classification systems based on commonalities among volcano morphology and eruptive style. On the one hand, detailed studies of individual volcanoes show that a single volcano often exhibits similar patterns of behaviour over multiple eruptive episodes; this observation has led to the idea that each volcano has its own distinctive pattern of behaviour (or “personality”). In contrast, volcano classification schemes define eruption “styles” referenced to “type” volcanoes (e.g. Plinian, Strombolian, Vulcanian); this approach implicitly assumes that common processes underpin volcanic activity and can be used to predict the nature, extent and ensuing hazards of individual volcanoes. Actual volcanic eruptions, however, often include multiple styles, and type volcanoes may experience atypical eruptions (e.g., violent explosive eruptions of Kilauea, Hawaii1). The volcanological community is thus left with a fundamental conundrum that pits the uniqueness of individual volcanic systems against generalization of common processes. Addressing this challenge represents a major challenge to volcano research.

  1. Cladistic analysis applied to the classification of volcanoes

    NASA Astrophysics Data System (ADS)

    Hone, D. W. E.; Mahony, S. H.; Sparks, R. S. J.; Martin, K. T.

    2007-11-01

    Cladistics is a systematic method of classification that groups entities on the basis of sharing similar characteristics in the most parsimonious manner. Here cladistics is applied to the classification of volcanoes using a dataset of 59 Quaternary volcanoes and 129 volcanic edifices of the Tohoku region, Northeast Japan. Volcano and edifice characteristics recorded in the database include attributes of volcano size, chemical composition, dominant eruptive products, volcano morphology, dominant landforms, volcano age and eruptive history. Without characteristics related to time the volcanic edifices divide into two groups, with characters related to volcano size, dominant composition and edifice morphology being the most diagnostic. Analysis including time based characteristics yields four groups with a good correlation between these groups and the two groups from the analysis without time for 108 out of 129 volcanic edifices. Thus when characters are slightly changed the volcanoes still form similar groupings. Analysis of the volcanoes both with and without time yields three groups based on compositional, eruptive products and morphological characters. Spatial clusters of volcanic centres have been recognised in the Tohoku region by Tamura et al. ( Earth Planet Sci Lett 197:105 106, 2002). The groups identified by cladistic analysis are distributed unevenly between the clusters, indicating a tendency for individual clusters to form similar kinds of volcanoes with distinctive but coherent styles of volcanism. Uneven distribution of volcano types between clusters can be explained by variations in dominant magma compositions through time, which are reflected in eruption products and volcanic landforms. Cladistic analysis can be a useful tool for elucidating dynamic igneous processes that could be applied to other regions and globally. Our exploratory study indicates that cladistics has promise as a method for classifying volcanoes and potentially elucidating dynamic

  2. Repeating volcano-tectonic earthquakes at Mt. Etna volcano (Sicily, Italy): characterization and evidences of crustal changes

    NASA Astrophysics Data System (ADS)

    Cannata, A.; Alparone, S.; Ursino, A.

    2012-12-01

    Repeating volcano-tectonic (VT) earthquakes, taking place at Mt. Etna during 1999-2009, were detected and analyzed to investigate their behavior. We found 735 families amounting to 2479 VT earthquakes, representing ~38% of all the analyzed VT earthquakes. The number of VT earthquakes making up the families ranges from 2 to 23. Over 70% of the families comprise 2 or 3 VT earthquakes and only 20 families by more than 10 events. The occurrence lifetime is also highly variable ranging from some minutes to ten years. In particular, more than half of the families have a lifetime shorter than 0.5 day and only ~10% longer than 1 year. On the basis of these results, most of the detected families were considered "burst-type", i.e., show swarm-like occurrence, and hence their origin cannot be explained by a temporally constant tectonic loading. Indeed, since the analyzed earthquakes take place in a volcanic area, the rocks are affected not only by tectonic stresses related to the fairly steady regional stress field but also by local stresses, caused by the volcano, such as magma batch intrusions/movements and gravitational loading. We focused on five groups of families characterized by the best repeatability over time, namely high number of events and long lifetime, located in the north-eastern, eastern and southern flanks of the volcano. Unlike the first four groups, which similarly to most of the detected families show swarm-like VT occurrences, group "v", located in the north-eastern sector, exhibits a more "tectonic" behavior with the events making up such a group spread over almost the entire analyzed period. It is clear how both occurrence and slip rates do not remain constant but vary over time, and such changes are time-related to the occurrence of the 2002-2003 eruption. We searched for waveform variations in VT earthquakes belonging to the group "v" and found changes that took place mainly in the 2002-2003 period. These consisted in a decreasing similarity of the

  3. Hubble Space Telescope Resolves Volcanoes on Io

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This picture is a composite of a black and white near infrared image of Jupiter and its satellite Io and a color image of Io at shorter wavelengths taken at almost the same time on March 5, 1994. These are the first images of a giant planet or its satellites taken by NASA's Hubble Space Telescope (HST) since the repair mission in December 1993.

    Io is too small for ground-based telescopes to see the surface details. The moon's angular diameter of one arc second is at the resolution limit of ground based telescopes.

    Many of these markings correspond to volcanoes that were first revealed in 1979 during the Voyager spacecraft flyby of Jupiter. Several of the volcanoes periodically are active because Io is heated by tides raised by Jupiter's powerful gravity.

    The volcano Pele appears as a dark spot surrounded by an irregular orange oval in the lower part of the image. The orange material has been ejected from the volcano and spread over a huge area. Though the volcano was first discovered by Voyager, the distinctive orange color of the volcanic deposits is a new discovery in these HST images. (Voyager missed it because its cameras were not sensitive to the near-infrared wavelengths where the color is apparent). The sulfur and sulfur dioxide that probably dominate Io's surface composition cannot produce this orange color, so the Pele volcano must be generating material with a more unusual composition, possibly rich in sodium.

    The Jupiter image, taken in near-infrared light, was obtained with HST's Wide Field and Planetary Camera in wide field mode. High altitude ammonia crystal clouds are bright in this image because they reflect infrared light before it is absorbed by methane in Jupiter's atmosphere. The most prominent feature is the Great Red Spot, which is conspicuous because of its high clouds. A cap of high-altitude haze appears at Jupiter's south pole.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the

  4. HUBBLE SPACE TELESCOPE RESOLVES VOLCANOES ON IO

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This picture is a composite of a black and white near infrared image of Jupiter and its satellite Io and a color image of Io at shorter wavelengths taken at almost the same time on March 5, 1994. These are the first images of a giant planet or its satellites taken by NASA's Hubble Space Telescope (HST) since the repair mission in December 1993. Io is too small for ground-based telescopes to see the surface details. The moon's angular diameter of one arc second is at the resolution limit of ground based telescopes. Many of these markings correspond to volcanoes that were first revealed in 1979 during the Voyager spacecraft flyby of Jupiter. Several of the volcanoes periodically are active because Io is heated by tides raised by Jupiter's powerful gravity. The volcano Pele appears as a dark spot surrounded by an irregular orange oval in the lower part of the image. The orange material has been ejected from the volcano and spread over a huge area. Though the volcano was first discovered by Voyager, the distinctive orange color of the volcanic deposits is a new discovery in these HST images. (Voyager missed it because its cameras were not sensitive to the near-infrared wavelengths where the color is apparent). The sulfur and sulfur dioxide that probably dominate Io's surface composition cannot produce this orange color, so the Pele volcano must be generating material with a more unusual composition, possibly rich in sodium. The Jupiter image, taken in near-infrared light, was obtained with HST's Wide Field and Planetary Camera in wide field mode. High altitude ammonia crystal clouds are bright in this image because they reflect infrared light before it is absorbed by methane in Jupiter's atmosphere. The most prominent feature is the Great Red Spot, which is conspicuous because of its high clouds. A cap of high-altitude haze appears at Jupiter's south pole. The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced

  5. Potentially active volcanoes of Peru - Observations using Landsat Thematic Mapper and Space Shuttle imagery

    NASA Technical Reports Server (NTRS)

    De Silva, S. L.; Francis, P. W.

    1990-01-01

    A synoptic study of the volcanoes of southern Peru (14-17 deg S), the northernmost part of the Central Volcanic Zone (CVZ 14-28 deg S) of the Andes, was conducted on the basis of Landsat TM images and color photography. The volcanoes were classified and their relative ages determined using subtle glacial-morphological features. Eight of them were postulated as potentially active. These are located in a narrow volcanic zone which probably reflects a steep dip of the Nazca plate through the zone of magma generation. The break in the trend of the volcanic arc possibly reflects the complexity of the crustal stress field above a major segment boundary in the subducting plate. There are also fields of mafic monogenetic centers in this region. In comparison with the southern part of the CVZ, the general paucity of older volcanic edifices north of 17 deg S suggested a more recent onset of volcanism, a possible result of the oblique subduction of the Nazca ridge and the consequent northward migration of its intersection with the Peru-Chile trench. This, together with the lack of any large silicic caldera systems and youthful dacite domes, suggested that there are real differences in the volcanic evolution of the two parts of the CVZ.

  6. Chronology, Eruption Duration, and Atmospheric Contribution of the Martian Volcano Apollinaris Patera

    USGS Publications Warehouse

    Robinson, M.S.; Mouginis-Mark, P. J.; Zimbelman, J.R.; Wu, S.S.C.; Ablin, K.K.; Howington-Kraus, A. E.

    1993-01-01

    Geologic mapping, thermal inertia measurements, and an analysis of the color (visual wavelengths) of the martian volcano Apollinaris Patera indicate the existence of two different surface materials, comprising an early, easily eroded edifice, and a more recent, competent fan on the southern flank. A chronology of six major events that is consistent with the present morphology of the volcano has been identified. We propose that large scale explosive activity occurred during the formation of the main edifice and that the distinctive fan on the southern flank appears to have been formed by lavas of low eruptive rate similar to those that form compound pahoehoe flow fields on Earth. A basal escarpment typically 500 m in relief and morphologically similar to the one surrounding Olympus Mons was produced between the formation of the main edifice and the fan, indicating multistage eruptions over a protracted period of time. Contact relations between the volcanic units and the adjacent chaotic material indicate that formation of the chaotic material occurred over an extended period of time and may be related to the volcanic activity that formed Apollinaris Patera. Stereophotogrammetric measurements permit the volume of the volcano to be estimated at 105 km3. From this volume measurement and an inferred eruption rate (1.5 ?? 10-2 km3 yr-1) we estimate the total eruption duration for the main edifice to be ???107 yrs. Plausible estimates of the exsolved volatile content of the parent magma imply that greater than 1015 kg of water vapor was released into the atmosphere as a consequence of this activity. This large amount of water vapor as well as other exsolved gases must have had a significant impact on local, and possibly global, climatic conditions. ?? 1993 Academic Press. All rights reserved.

  7. Holocene tephrostratigraphy of southern Chiloé Continental (Andean southern volcanic zone; ~43°S), Chile

    NASA Astrophysics Data System (ADS)

    Lachowycz, S.; Smith, V. C.; Pyle, D. M.; Mather, T. A.

    2012-12-01

    The eruptive history of the volcanoes in the southern part of the Andean Southern Volcanic Zone (42.5-45°S) is very poorly constrained: only several late Quaternary eruptions have been identified, mostly from study of sparse roadcuts [1]. In this study, we further constrain the Holocene explosive eruption history around 43°S by identifying and analysing tephra layers preserved in a ~3.25m long peat core from Cuesta Moraga [2], ~35km east of Yanteles volcano. Cryptotephra was extracted following the method of [3], in addition to macrotephra; owing to the vicinity of the sampling site to the tephra sources, cryptotephra was found throughout the core stratigraphy, but was sufficiently variable in concentration that discrete layers were identifiable and attributed to specific eruptions. Chemical analysis of the glass by electron microprobe shows that the tephra layers originate from a number of volcanoes in the region. This new tephrostratigraphy improves our knowledge of the important history of explosive volcanism in this area, potentially tying the tephrostratigraphies of surrounding areas (e.g., [4]) and allowing improved evaluation of regional volcanic risk. [1] Naranjo, J.A.., and C. R. Stern, 2004. Holocene tephrochronology of the southernmost part (42°30'-45°S) of the Andean Southern Volcanic Zone. Revista geológica de Chile, 31, pp. 225-240. [2] Heusser, C.J., et al., 1992. Paleoecology of late Quaterary deposits in Chiloé Continental, Chile. Revista Chilena de Historia Natural, 65, pp. 235-245. [3] Blockley, S.P.E., et al., 2005. A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments. Quaternary Science Reviews, 24, pp. 1952-1960. [4] Watt, S.F.L., et al., 2011. Holocene tephrochronology of the Hualaihue region (Andean southern volcanic zone, ~42°S), southern Chile. Quaternary International, 246, pp. 324-343.

  8. Global synthesis of volcano deformation: Results of the Volcano Deformation Task Force

    NASA Astrophysics Data System (ADS)

    Pritchard, M. E.; Jay, J.; Biggs, J.; Ebmeier, S. K.; Delgado, F.

    2013-12-01

    Ground deformation in volcanic regions is being observed more frequently -- the number of known deforming volcanoes has increased from 44 in 1997 to more than 210 in 2013 thanks in large part thanks to the availability of satellite InSAR observations. With the launch of new SAR satellites in the coming years devoted to global deformation monitoring, the number of well-studied episodes of volcano deformation will continue to increase. But evaluating the significance of the observed deformation is not always straightforward -- how often do deformation episodes lead to eruption? Are there certain characteristics of the deformation or the volcano that make the linkage between deformation and eruption more robust -- for example the duration or magnitude of the ground deformation and/or the composition and tectonic setting of the volcano? To answer these questions, a global database of volcano deformation events is needed. Recognizing the need for global information on volcano deformation and the opportunity to address it with InSAR and other techniques, we formed the Volcano Deformation Database Task force as part of Global Volcano Model. The three objectives of our organization are: 1) to compile deformation observations of all volcanoes globally into appropriate formats for WOVOdat and the Global Volcanism Program of the Smithsonian Institution. 2) document any relation between deformation events and eruptions for the Global assessment of volcanic hazard and risk report for 2015 (GAR15) for the UN. 3) to better link InSAR and other remote sensing observations to volcano observatories. We present the first results from our global study of the relation between deformation and eruptions, including case studies of particular eruptions. We compile a systematically-observed catalog of >500 volcanoes with observation windows up to 20 years. Of 90 volcanoes showing deformation, 40 erupted. The positive predictive value (PPV = 0.44) linking deformation and eruption on this

  9. Darwin's triggering mechanism of volcano eruptions

    NASA Astrophysics Data System (ADS)

    Galiev, Shamil

    2010-05-01

    Charles Darwin wrote that ‘… the elevation of many hundred square miles of territory near Concepcion is part of the same phenomenon, with that splashing up, if I may so call it, of volcanic matter through the orifices in the Cordillera at the moment of the shock;…' and ‘…a power, I may remark, which acts in paroxysmal upheavals like that of Concepcion, and in great volcanic eruptions,…'. Darwin reports that ‘…several of the great chimneys in the Cordillera of central Chile commenced a fresh period of activity ….' In particular, Darwin reported on four-simultaneous large eruptions from the following volcanoes: Robinson Crusoe, Minchinmavida, Cerro Yanteles and Peteroa (we cite the Darwin's sentences following his The Voyage of the Beagle and researchspace. auckland. ac. nz/handle/2292/4474). Let us consider these eruptions taking into account the volcano shape and the conduit. Three of the volcanoes (Minchinmavida (2404 m), Cerro Yanteles (2050 m), and Peteroa (3603 m)) are stratovolcanos and are formed of symmetrical cones with steep sides. Robinson Crusoe (922 m) is a shield volcano and is formed of a cone with gently sloping sides. They are not very active. We may surmise, that their vents had a sealing plug (vent fill) in 1835. All these volcanoes are conical. These common features are important for Darwin's triggering model, which is discussed below. The vent fill material, usually, has high level of porosity and a very low tensile strength and can easily be fragmented by tension waves. The action of a severe earthquake on the volcano base may be compared with a nuclear blast explosion of the base. It is known, that after a underground nuclear explosion the vertical motion and the surface fractures in a tope of mountains were observed. The same is related to the propagation of waves in conical elements. After the explosive load of the base. the tip may break and fly off at high velocity. Analogous phenomenon may be generated as a result of a

  10. Darwin's triggering mechanism of volcano eruptions

    NASA Astrophysics Data System (ADS)

    Galiev, Shamil

    2010-05-01

    Charles Darwin wrote that ‘… the elevation of many hundred square miles of territory near Concepcion is part of the same phenomenon, with that splashing up, if I may so call it, of volcanic matter through the orifices in the Cordillera at the moment of the shock;…' and ‘…a power, I may remark, which acts in paroxysmal upheavals like that of Concepcion, and in great volcanic eruptions,…'. Darwin reports that ‘…several of the great chimneys in the Cordillera of central Chile commenced a fresh period of activity ….' In particular, Darwin reported on four-simultaneous large eruptions from the following volcanoes: Robinson Crusoe, Minchinmavida, Cerro Yanteles and Peteroa (we cite the Darwin's sentences following his The Voyage of the Beagle and researchspace. auckland. ac. nz/handle/2292/4474). Let us consider these eruptions taking into account the volcano shape and the conduit. Three of the volcanoes (Minchinmavida (2404 m), Cerro Yanteles (2050 m), and Peteroa (3603 m)) are stratovolcanos and are formed of symmetrical cones with steep sides. Robinson Crusoe (922 m) is a shield volcano and is formed of a cone with gently sloping sides. They are not very active. We may surmise, that their vents had a sealing plug (vent fill) in 1835. All these volcanoes are conical. These common features are important for Darwin's triggering model, which is discussed below. The vent fill material, usually, has high level of porosity and a very low tensile strength and can easily be fragmented by tension waves. The action of a severe earthquake on the volcano base may be compared with a nuclear blast explosion of the base. It is known, that after a underground nuclear explosion the vertical motion and the surface fractures in a tope of mountains were observed. The same is related to the propagation of waves in conical elements. After the explosive load of the base. the tip may break and fly off at high velocity. Analogous phenomenon may be generated as a result of a

  11. A Benthic Invertebrate Survey of Jun Jaegyu Volcano: An active undersea volcano in Antarctic Sound, Antarctica

    NASA Astrophysics Data System (ADS)

    Quinones, G.; Brachfeld, S.; Gorring, M.; Prezant, R. S.; Domack, E.

    2005-12-01

    Jun Jaegyu volcano, an Antarctic submarine volcano, was dredged in May 2004 during cruise 04-04 of the RV Laurence M. Gould to determine rock, sediment composition and marine macroinvertebrate diversity. The objectives of this study are to examine the benthic assemblages and biodiversity present on a young volcano. The volcano is located on the continental shelf of the northeastern Antarctic Peninsula, where recent changes in surface temperature and ice shelf stability have been observed. This volcano was originally swath-mapped during cruise 01-07 of the Research Vessel-Ice Breaker Nathaniel B. Palmer. During LMG04-04 we also studied the volcano using a SCUD video camera, and performed temperature surveys along the flanks and crest. Both the video and the dredge indicate a seafloor surface heavily colonized by benthic organisms. Indications of fairly recent lava flows are given by the absence of marine life on regions of the volcano. The recovered dredge material was sieved, and a total of thirty-three invertebrates were extracted. The compilation of invertebrate community data can subsequently be compared to other benthic invertebrate studies conducted along the peninsula, which can determine the regional similarity of communities over time, their relationship to environmental change and health, if any, and their relationship to geologic processes in Antarctic Sound. Twenty-two rock samples, all slightly weathered and half bearing encrusted organisms, were also analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Except for one conglomerate sample, all are alkali basalts and share similar elemental compositions with fresh, unweathered samples from the volcano. Two of the encrusted basalt samples have significantly different compositions than the rest. We speculate this difference could be due to water loss during sample preparation, loss of organic carbon trapped within the vesicles of the samples and/or elemental uptake by the

  12. SAR4Volcanoes: an international ASI funded research project on volcano deformation through new generation SAR sensors

    NASA Astrophysics Data System (ADS)

    Sansosti, E.; Pepe, S.; Solaro, G.; Casu, F.; Tizzani, P.; Acocella, V.; Ruch, J.; Nobile, A.; Puglisi, G.; Guglielmino, F.; Zoffoli, S.

    2012-04-01

    Volcano deformation monitoring is crucial to understand how magma emplaces, propagates and erupts. Therefore, volcano deformation research projects are particularly important opportunities to improve our understanding of volcano dynamics. SAR4Volcanoes is a 2-year research project funded by the Italian Space Agency (ASI) within the framework of a cooperation agreement with the Japan Aerospace Exploration Agency (JAXA). It focuses on volcano deformation analysis through Differential SAR Interferometry (DInSAR) techniques by means of COSMO-SkyMed and ALOS data, through the joint use of L-band and X-band SAR data. It also aims to the identification of methods and techniques to support decision making in emergency cases. Main target volcanoes in the projects are Etna, Vesuvio, Campi Flegrei and Stromboli (Italy) and Sakurajima and Kirishima (Japan). Secondary target volcanoes include recently or currently erupting volcanoes, as El Hierro (Spain), Nabro (Ethiopia) and Galapagos volcanoes (Ecuador). Since the project kickoff (July 2011) a large number of COSMO-SkyMed data has been acquired at these volcanoes; in some cases, the acquisitions are available almost at every satellite orbit, with an average interval down to 4 days. On these premises, the project represents an important opportunity to: (1) collect a significant amount of X-band data on active and erupting volcanoes and (2) study surface deformation to understand magma dynamics in different volcanic settings. We will present preliminary results on the ground deformation analysis of the main and secondary target volcanoes. In particular, target volcanoes without a pre-project archive are analyzed using single deformation maps, while those with archives are analysed through a time series approach, based on the SBAS technique.

  13. Volcano hazard mitigation program in Indonesia

    USGS Publications Warehouse

    Sudradjat, A.

    1990-01-01

    Volcanological investigations in Indonesia were started in the 18th century, when Valentijn in 1726 prepared a chronological report of the eruption of Banda Api volcno, Maluku. Modern and intensive volcanological studies did not begin until the catastrophic eruption of Kelut volcano, East Java, in 1919. The eruption took 5,011 lives and destroyed thousands of acres of coffee plantation. An eruption lahar generated by the crater lake water mixed with volcanic eruptions products was the cause of death for a high number of victims. An effort to mitigate the danger from volcanic eruption was first initiated in 1921 by constructing a tunnel to drain the crater lake water of Kelut volcano. At the same time a Volcanological Survey was established by the government with the responsibility of seeking every means for minimizing the hazard caused by volcanic eruption. 

  14. Investigation of prototype volcano surveillance network

    NASA Technical Reports Server (NTRS)

    Eaton, J. P. (Principal Investigator); Ward, P. L.

    1973-01-01

    The author has identified the following significant results. Earthquake counters in Guatemala were being installed between February 13 and 17. The volcano Fuego began erupting ash and ash flows on February 23. On February 17, 6 days before the eruption there were 80 earthquakes at two counters 5 and 15 km from the volcano. This was a substantial increase of a fairly constant level of events per day recorded for the previous four days. A counter 30 km away did not show an increase. Had the DCP been operating longer and had the data been sent immediately from Goddard, it might have been possible to warn of a possible eruption six days in advance.

  15. Natrocarbonatite tephra of Kerimasi volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Hay, Richard L.

    1983-10-01

    Carbonatite tephra was discharged in the final eruptive phase of Kerimasi, an extinct nephelinite volcano in the eastern rift valley of northern Tanzania. The tephra was dominantly of alkali carbonatite composition, thus providing the first well-documented example of premodern natrocarbonatite volcanism. The principal carbonate mineral was nyerereite, which is the dominant mineral in modern natrocarbonatite lava flows of the adjacent volcano Oldoinyo Lengai. The nyerereite of Kerimasi was leached of its alkalis by meteoric water and is now represented by calcite pseudomorphs. Natrocarbonatite tephra of Kerimasi shows that the alkali-rich eruptive rocks of Oldoinyo Lengai are not unique, thus supporting the hypothesis that carbonatite magmas associated with nephelinite volcanism were originally alkaline and that the subvolcanic calcitic carbonatites are a residuum from which the alkalis have been removed, either by volcanism or fenetizing fluids. A hypothesis to be tested is that eruptive carbonatite magma is, worldwide, commonly and perhaps dominantly of natrocarbonatite composition.

  16. Voluminous submarine lava flows from Hawaiian volcanoes

    SciTech Connect

    Holcomb, R.T.; Moore, J.G.; Lipman, P.W.; Belderson, R.H.

    1988-05-01

    The GLORIA long-range sonar imaging system has revealed fields of large lava flows in the Hawaiian Trough east and south of Hawaii in water as deep as 5.5 km. Flows in the most extensive field (110 km long) have erupted from the deep submarine segment of Kilauea's east rift zone. Other flows have been erupted from Loihi and Mauna Loa. This discovery confirms a suspicion, long held from subaerial studies, that voluminous submarine flows are erupted from Hawaiian volcanoes, and it supports an inference that summit calderas repeatedly collapse and fill at intervals of centuries to millenia owing to voluminous eruptions. These extensive flows differ greatly in form from pillow lavas found previously along shallower segments of the rift zones; therefore, revision of concepts of volcano stratigraphy and structure may be required.

  17. Southern blotting.

    PubMed

    Brown, T

    2001-05-01

    Southern blotting is the transfer of DNA fragments from an electrophoresis gel to a membrane support (the properties and advantages of the different types of membrane, transfer buffer, and transfer method are discussed in detail), resulting in immobilization of the DNA fragments, so the membrane carries a semipermanent reproduction of the banding pattern of the gel. After immobilization, the DNA can be subjected to hybridization analysis, enabling bands with sequence similarity to a labeled probe to be identified. This appendix describes Southern blotting via upward capillary transfer of DNA from an agarose gel onto a nylon or nitrocellulose membrane, using a high-salt transfer buffer to promote binding of DNA to the membrane. With the high-salt buffer, the DNA becomes bound to the membrane during transfer but not permanently immobilized. Immobilization is achieved by UV irradiation (for nylon) or baking (for nitrocellulose). A Support Protocol describes how to calibrate a UV transilluminator for optimal UV irradiation of a nylon membrane. An alternate protocol details transfer using nylon membranes and an alkaline buffer, and is primarily used with positively charged nylon membranes. The advantage of this combination is that no post-transfer immobilization step is required, as the positively charged membrane binds DNA irreversibly under alkaline transfer conditions. The method can also be used with neutral nylon membranes but less DNA will be retained. A second alternate protocol describes a transfer method based on a different transfer-stack setup. The traditional method of upward capillary transfer of DNA from gel to membrane described in the first basic and alternate protocols has certain disadvantages, notably the fact that the gel can become crushed by the weighted filter papers and paper towels that are laid on top of it. This slows down the blotting process and may reduce the amount of DNA that can be transferred. The downward capillary method described in

  18. Muria Volcano, Island of Java, Indonesia

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view of the north coast of central Java, Indonesia centers on the currently inactive Muria Volcano (6.5S, 111.0E). Muria is 5,330 ft. tall and lies just north of Java's main volcanic belt which runs east - west down the spine of the island attesting to the volcanic origin of the more than 1,500 Indonesian Islands.

  19. Imaging Magma Plumbing Beneath Askja Volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Greenfield, T. S.; White, R. S.

    2015-12-01

    Using a dense seismic network we have imaged the plumbing system beneath Askja, a large central volcano in the Northern Volcanic Zone, Iceland. Local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. We find a pronounced low-velocity anomaly beneath the caldera at a depth of ~7 km around the depth of the brittle-ductile transition. The anomaly is ~10% slower than the initial best fitting 1D model and has a Vp/Vs ratio higher than the surrounding crust, suggesting the presence of increased temperature or partial melt. We use relationships between mineralogy and seismic velocities to estimate that this region contains ~10% partial melt, similar to observations made at other volcanoes such as Kilauea. This low-velocity body is deeper than the depth range suggested by geodetic studies of a deflating source beneath Askja. Beneath the large low-velocity zone a region of reduced velocities extends into the lower crust and is coincident with seismicity in the lower crust. This is suggestive of a high temperature channel into the lower crust which could be the pathway for melt rising from the mantle. This melt either intrudes into the lower crust or stalls at the brittle-ductile boundary in the imaged body. Above this, melt can travel into the fissure swarm through large dikes or erupt within the Askja caldera itself.We generate travel time tables using a finite difference technique and the residuals used to simultaneously solve for both the earthquake locations and velocity structure. The 2014-15 Bárðarbunga dike intrusion has provided a 45 km long, distributed source of large earthquakes which are well located and provide accurate arrival time picks. Together with long-term background seismicity these provide excellent illumination of the Askja volcano from all directions.hhhh

  20. On the morphometry of terrestrial shield volcanoes

    NASA Astrophysics Data System (ADS)

    Grosse, Pablo; Kervyn, Matthieu

    2016-04-01

    Shield volcanoes are described as low angle edifices that have convex up topographic profiles and are built primarily by the accumulation of lava flows. This generic view of shields' morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galapagos). Here, the morphometry of over 150 monogenetic and polygenetic shield volcanoes, identified inthe Global Volcanism Network database, are analysed quantitatively from 90-meter resolution DEMs using the MORVOLC algorithm. An additional set of 20 volcanoes identified as stratovolcanoes but having low slopes and being dominantly built up by accumulation of lava flows are documented for comparison. Results show that there is a large variation in shield size (volumes range from 0.1 to >1000 km3), profile shape (height/basal width ratios range from 0.01 to 0.1), flank slope gradients, elongation and summit truncation. Correlation and principal component analysis of the obtained quantitative database enables to identify 4 key morphometric descriptors: size, steepness, plan shape and truncation. Using these descriptors through clustering analysis, a new classification scheme is proposed. It highlights the control of the magma feeding system - either central, along a linear structure, or spatially diffuse - on the resulting shield volcano morphology. Genetic relationships and evolutionary trends between contrasted morphological end-members can be highlighted within this new scheme. Additional findings are that the Galapagos-type morphology with a central deep caldera and steep upper flanks are characteristic of other shields. A series of large oceanic shields have slopes systematically much steeper than the low gradients (<4-8°) generally attributed to large Hawaiian-type shields. Finally, the continuum of morphologies from flat shields to steeper complex volcanic constructs considered as stratovolcanoes calls for a revision of this oversimplified

  1. Volcano Analog Exploration Opportunities in Reunion Island

    NASA Astrophysics Data System (ADS)

    Pignolet, Guy; Bertil, Alain; Huet, Patrice

    While general information has already been given in previous papers about the SALM (Moon Mars Analogue Site) in Reunion Island, this status papers gives more useful details with : - a survey of Lava Tubes and other volcanic structures at Piton de la Fournaise volcano that are suitable for Moon and Mars analogue studies, - an overview of sampling and other exploration and evaluation techniques that may be tested on the analogue site for future use on Solar System bodies

  2. Silicic magma generation at Askja volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Sigmarsson, O.

    2009-04-01

    Rate of magma differentiation is an important parameter for hazard assessment at active volcanoes. However, estimates of these rates depend on proper understanding of the underlying magmatic processes and magma generation. Differences in isotope ratios of O, Th and B between silicic and in contemporaneous basaltic magmas have been used to emphasize their origin by partial melting of hydrothermally altered metabasaltic crust in the rift-zones favoured by a strong geothermal gradient. An alternative model for the origin of silicic magmas in the Iceland has been proposed based on U-series results. Young mantle-derived mafic protolith is thought to be metasomatized and partially melted to form the silicic end-member. However, this model underestimates the compositional variations of the hydrothermally-altered basaltic crust. New data on U-Th disequilibria and O-isotopes in basalts and dacites from Askja volcano reveal a strong correlation between (230Th/232Th) and delta 18O. The 1875 AD dacite has the lowest Th- and O isotope ratios (0.94 and -0.24 per mille, respectively) whereas tephra of evolved basaltic composition, erupted 2 months earlier, has significantly higher values (1.03 and 2.8 per mille, respectively). Highest values are observed in the most recent basalts (erupted in 1920 and 1961) inside the Askja caldera complex and out on the associated fissure swarm (Sveinagja basalt). This correlation also holds for older magma such as an early Holocene dacites, which eruption may have been provoked by rapid glacier thinning. Silicic magmas at Askja volcano thus bear geochemical signatures that are best explained by partial melting of extensively hydrothermally altered crust and that the silicic magma source has remained constant during the Holocene at least. Once these silicic magmas are formed they appear to erupt rapidly rather than mixing and mingling with the incoming basalt heat-source that explains lack of icelandites and the bi-modal volcanism at Askja

  3. Continuous monitoring of Mount St. Helens Volcano

    USGS Publications Warehouse

    Spall, H.

    1980-01-01

    Day by day monitoring of the Mount St. Helens Volcano. These are four scenarios, very different scenarios, that can occur in a average week at Mount St. Helens. Ranging from eruptions of gas and to steam to eruptions of ash and pyroclastic flows to even calm days. This example of monitoring illustrates the differences from day to day volcanic activities at Mount St. Helens. 

  4. Buried caldera of mauna kea volcano, hawaii.

    PubMed

    Porter, S C

    1972-03-31

    An elliptical caldera (2.1 by 2.8 kilometers) at the summit of Mauna Kea volcano is inferred to lie buried beneath hawaiite lava flows and pyroclastic cones at an altitude of approximately 3850 meters. Stratigraphic relationships indicate that hawaiite eruptions began before a pre-Wisconsin period of ice-cap glaciation and that the crest of the mountain attained its present altitude and gross form during a glaciation of probable Early Wisconsin age. PMID:17842285

  5. Decision Analysis Tools for Volcano Observatories

    NASA Astrophysics Data System (ADS)

    Hincks, T. H.; Aspinall, W.; Woo, G.

    2005-12-01

    Staff at volcano observatories are predominantly engaged in scientific activities related to volcano monitoring and instrumentation, data acquisition and analysis. Accordingly, the academic education and professional training of observatory staff tend to focus on these scientific functions. From time to time, however, staff may be called upon to provide decision support to government officials responsible for civil protection. Recognizing that Earth scientists may have limited technical familiarity with formal decision analysis methods, specialist software tools that assist decision support in a crisis should be welcome. A review is given of two software tools that have been under development recently. The first is for probabilistic risk assessment of human and economic loss from volcanic eruptions, and is of practical use in short and medium-term risk-informed planning of exclusion zones, post-disaster response, etc. A multiple branch event-tree architecture for the software, together with a formalism for ascribing probabilities to branches, have been developed within the context of the European Community EXPLORIS project. The second software tool utilizes the principles of the Bayesian Belief Network (BBN) for evidence-based assessment of volcanic state and probabilistic threat evaluation. This is of practical application in short-term volcano hazard forecasting and real-time crisis management, including the difficult challenge of deciding when an eruption is over. An open-source BBN library is the software foundation for this tool, which is capable of combining synoptically different strands of observational data from diverse monitoring sources. A conceptual vision is presented of the practical deployment of these decision analysis tools in a future volcano observatory environment. Summary retrospective analyses are given of previous volcanic crises to illustrate the hazard and risk insights gained from use of these tools.

  6. Geothermal Exploration of Newberry Volcano, Oregon

    SciTech Connect

    Waibel, Albert F.; Frone, Zachary S.; Blackwell, David D.

    2014-12-01

    Davenport Newberry (Davenport) has completed 8 years of exploration for geothermal energy on Newberry Volcano in central Oregon. Two deep exploration test wells were drilled by Davenport on the west flank of the volcano, one intersected a hydrothermal system; the other intersected isolated fractures with no hydrothermal interconnection. Both holes have bottom-hole temperatures near or above 315°C (600°F). Subsequent to deep test drilling an expanded exploration and evaluation program was initiated. These efforts have included reprocessing existing data, executing multiple geological, geophysical, geochemical programs, deep exploration test well drilling and shallow well drilling. The efforts over the last three years have been made possible through a DOE Innovative Exploration Technology (IET) Grant 109, designed to facilitate innovative geothermal exploration techniques. The combined results of the last 8 years have led to a better understanding of the history and complexity of Newberry Volcano and improved the design and interpretation of geophysical exploration techniques with regard to blind geothermal resources in volcanic terrain.

  7. Mineralized microbes from Giggenbach submarine volcano

    NASA Astrophysics Data System (ADS)

    Jones, Brian; de Ronde, C. E. J.; Renaut, Robin W.

    2008-08-01

    The Giggenbach submarine volcano, which forms part of the Kermadec active arc front, is located ˜780 km NNE of the North Island of New Zealand. Samples collected from chimneys associated with seafloor hydrothermal vents on this volcano, at a depth of 160-180 m, contain silicified microbes and microbes entombed in reticular Fe-rich precipitates. The mineralized biota includes filamentous, rod-shaped, and rare coccoid microbes. In the absence of organic carbon for rDNA analysis or preserved cells, the taxonomic affinity of these microbes, in terms of extant taxa, remains questionable because of their architectural simplicity and the paucity of taxonomically significant features. The three-dimensional preservation of the microbes indicates rapid mineralization with a steady supply of supersaturated fluids to the nucleation sites present on the surfaces of the microbes. The mineralization styles evident in the microbes from the Giggenbach submarine volcano are similar to those associated with mineralized microbes found in terrestrial hot spring deposits in New Zealand, Iceland, Yellowstone, and Kenya. These similarities exist even though the microbes are probably different and the fluids become supersaturated with respect to opal-A by different mechanisms. For ancient rocks it means that interpretations of the depositional settings cannot be based solely on the silicified microbes or their style of silicification.

  8. Electrical structure of Newberry Volcano, Oregon

    USGS Publications Warehouse

    Fitterman, D.V.; Stanley, W.D.; Bisdorf, R.J.

    1988-01-01

    From the interpretation of magnetotelluric, transient electromagnetic, and Schlumberger resistivity soundings, the electrical structure of Newberry Volcano in central Oregon is found to consist of four units. From the surface downward, the geoelectrical units are 1) very resistive, young, unaltered volcanic rock, (2) a conductive layer of older volcanic material composed of altered tuffs, 3) a thick resistive layer thought to be in part intrusive rocks, and 4) a lower-crustal conductor. This model is similar to the regional geoelectrical structure found throughout the Cascade Range. Inside the caldera, the conductive second layer corresponds to the steep temperature gradient and alteration minerals observed in the USGS Newberry 2 test-hole. Drill hole information on the south and north flanks of the volcano (test holes GEO N-1 and GEO N-3, respectively) indicates that outside the caldera the conductor is due to alteration minerals (primarily smectite) and not high-temperature pore fluids. On the flanks of Newberry the conductor is generally deeper than inside the caldera, and it deepens with distance from the summit. A notable exception to this pattern is seen just west of the caldera rim, where the conductive zone is shallower than at other flank locations. The volcano sits atop a rise in the resistive layer, interpreted to be due to intrusive rocks. -from Authors

  9. Deep structure of Medicine Lake volcano, California

    USGS Publications Warehouse

    Ritter, J.R.R.; Evans, J.R.

    1997-01-01

    Medicine Lake volcano (MLV) in northeastern California is the largest-volume volcano in the Cascade Range. The upper-crustal structure of this Quaternary shield volcano is well known from previous geological and geophysical investigations. In 1981, the U.S. Geological Survey conducted a teleseismic tomography experiment on MLV to explore its deeper structure. The images we present, calculated using a modern form of the ACH-inversion method, reveal that there is presently no hint of a large (> 100 km3), hot magma reservoir in the crust. The compressional-wave velocity perturbations show that directly beneath MLV's caldera there is a zone of increased seismic velocity. The perturbation amplitude is +10% in the upper crust, +5% in the lower crust, and +3% in the lithospheric mantle. This positive seismic velocity anomaly presumably is caused by mostly subsolidus gabbroic intrusive rocks in the crust. Heat and melt removal are suggested as the cause in the upper mantle beneath MLV, inferred from petro-physical modeling. The increased seismic velocity appears to be nearly continuous to 120 km depth and is a hint that the original melts come at least partly from the lower lithospheric mantle. Our second major finding is that the upper mantle southeast of MLV is characterized by relatively slow seismic velocities (-1%) compared to the northwest side. This anomaly is interpreted to result from the elevated temperatures under the northwest Basin and Range Province.

  10. Atmospheric influence on volcano-acoustic signals

    NASA Astrophysics Data System (ADS)

    Matoza, Robin; de Groot-Hedlin, Catherine; Hedlin, Michael; Fee, David; Garcés, Milton; Le Pichon, Alexis

    2010-05-01

    Volcanoes are natural sources of infrasound, useful for studying infrasonic propagation in the atmosphere. Large, explosive volcanic eruptions typically produce signals that can be recorded at ranges of hundreds of kilometers propagating in atmospheric waveguides. In addition, sustained volcanic eruptions can produce smaller-amplitude repetitive signals recordable at >10 km range. These include repetitive impulsive signals and continuous tremor signals. The source functions of these signals can remain relatively invariant over timescales of weeks to months. Observed signal fluctuations from such persistent sources at an infrasound recording station may therefore be attributed to dynamic atmospheric propagation effects. We present examples of repetitive and sustained volcano infrasound sources at Mount St. Helens, Washington and Kilauea Volcano, Hawaii, USA. The data recorded at >10 km range show evidence of propagation effects induced by tropospheric variability at the mesoscale and microscale. Ray tracing and finite-difference simulations of the infrasound propagation produce qualitatively consistent results. However, the finite-difference simulations indicate that low-frequency effects such as diffraction, and scattering from topography may be important factors for infrasonic propagation at this scale.

  11. Seismic Tomography of Erebus Volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Zandomeneghi, Daria; Kyle, Philip; Miller, Pnina; Snelson, Catherine; Aster, Richard

    2010-02-01

    Mount Erebus (77°32'S, 167°10'E elevation 3794 meters) is the most active volcano in Antarctica and is well known for its persistent lava lake. The lake constitutes an “open window” into the conduit and underlying feeding system and offers a rare opportunity to observe a shallow convecting magmatic system. Imaging and modeling of the internal structure of Erebus volcano are best done through compiling information from arrays of seismometers positioned strategically around the volcano. From these data, the three-dimensional (3-D) structure of the conduit can be pieced together. Building this 3-D model of Erebus was a main goal of the seismic tomographic experiment Tomo Erebus (TE). During the 2007-2008 austral field season, 23 intermediate-period seismometers were installed to contribute data, through the winter, for the passive-source aspect of the experiment. One year later, 100 three-component short-period stations were deployed to record 16 chemical blasts (see Figure 1).

  12. Citizen Empowerment in Volcano Monitoring, Communication and Decision-Making at Tungurahua Volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Bartel, B.; Mothes, P. A.

    2013-05-01

    Trained citizen volunteers called vigías have worked to help monitor and communicate warnings about Tungurahua volcano, in Ecuador, since the volcano reawoke in 1999. The network, organized by the scientists of Ecuacor's Instituto Geofísico de la Escuela Politécnica Nacional (Geophysical Institute) and the personnel from the Secretaría Nacional de Gestión de Riesgos (Risk Management, initially the Civil Defense), has grown to well over 20 observers living around the volcano who communicate regularly via handheld two-way radios. Interviews with participants in 2010 indicate that the network enables direct communication between communities and authorities, engenders trust in scientists and emergency response personnel, builds community, and empowers communities to make decisions in times of crisis.

  13. Citizen empowerment in volcano monitoring, communication and decision-making at Tungurahua volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Bartel, B. A.; Mothes, P. A.

    2013-12-01

    Trained citizen volunteers called vigías have worked to help monitor and communicate warnings about Tungurahua volcano, in Ecuador, since the volcano reawoke in 1999. The network, organized by the scientists of Ecuador's Instituto Geofísico de la Escuela Politécnica Nacional (Geophysical Institute) and the personnel from the Secretaría Nacional de Gestión de Riesgos (Risk Management, initially the Civil Defense), has grown to more than 20 observers living around the volcano who communicate regularly via handheld two-way radios. Interviews with participants conducted in 2010 indicate that the network enables direct communication between communities and authorities; engenders trust in scientists and emergency response personnel; builds community; and empowers communities to make decisions in times of crisis.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  15. Geologic map of Medicine Lake volcano, northern California

    USGS Publications Warehouse

    Donnelly-Nolan, Julie M.

    2011-01-01

    Medicine Lake volcano forms a broad, seemingly nondescript highland, as viewed from any angle on the ground. Seen from an airplane, however, treeless lava flows are scattered across the surface of this potentially active volcanic edifice. Lavas of Medicine Lake volcano, which range in composition from basalt through rhyolite, cover more than 2,000 km2 east of the main axis of the Cascade Range in northern California. Across the Cascade Range axis to the west-southwest is Mount Shasta, its towering volcanic neighbor, whose stratocone shape contrasts with the broad shield shape of Medicine Lake volcano. Hidden in the center of Medicine Lake volcano is a 7 km by 12 km summit caldera in which nestles its namesake, Medicine Lake. The flanks of Medicine Lake volcano, which are dotted with cinder cones, slope gently upward to the caldera rim, which reaches an elevation of nearly 8,000 ft (2,440 m). The maximum extent of lavas from this half-million-year-old volcano is about 80 km north-south by 45 km east-west. In postglacial time, 17 eruptions have added approximately 7.5 km3 to its total estimated volume of 600 km3, and it is considered to be the largest by volume among volcanoes of the Cascades arc. The volcano has erupted nine times in the past 5,200 years, a rate more frequent than has been documented at all other Cascades arc volcanoes except Mount St. Helens.

  16. The critical role of volcano monitoring in risk reduction

    NASA Astrophysics Data System (ADS)

    Tilling, R. I.

    2008-01-01

    Data from volcano-monitoring studies constitute the only scientifically valid basis for short-term forecasts of a future eruption, or of possible changes during an ongoing eruption. Thus, in any effective hazards-mitigation program, a basic strategy in reducing volcano risk is the initiation or augmentation of volcano monitoring at historically active volcanoes and also at geologically young, but presently dormant, volcanoes with potential for reactivation. Beginning with the 1980s, substantial progress in volcano-monitoring techniques and networks - ground-based as well space-based - has been achieved. Although some geochemical monitoring techniques (e.g., remote measurement of volcanic gas emissions) are being increasingly applied and show considerable promise, seismic and geodetic methods to date remain the techniques of choice and are the most widely used. Availability of comprehensive volcano-monitoring data was a decisive factor in the successful scientific and governmental responses to the reawakening of Mount St. elens (Washington, USA) in 1980 and, more recently, to the powerful explosive eruptions at Mount Pinatubo (Luzon, Philippines) in 1991. However, even with the ever-improving state-of-the-art in volcano monitoring and predictive capability, the Mount St. Helens and Pinatubo case histories unfortunately still represent the exceptions, rather than the rule, in successfully forecasting the most likely outcome of volcano unrest.

  17. Living on Active Volcanoes - The Island of Hawai'i

    USGS Publications Warehouse

    Heliker, Christina; Stauffer, Peter H.; Hendley, James W., II

    1997-01-01

    People on the Island of Hawai'i face many hazards that come with living on or near active volcanoes. These include lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and tsunamis (giant seawaves). As the population of the island grows, the task of reducing the risk from volcano hazards becomes increasingly difficult. To help protect lives and property, U.S. Geological Survey (USGS) scientists at the Hawaiian Volcano Observatory closely monitor and study Hawai'i's volcanoes and issue timely warnings of hazardous activity.

  18. Mud volcanoes of the Orinoco Delta, Eastern Venezuela

    USGS Publications Warehouse

    Aslan, A.; Warne, A.G.; White, W.A.; Guevara, E.H.; Smyth, R.C.; Raney, J.A.; Gibeaut, J.C.

    2001-01-01

    Mud volcanoes along the northwest margin of the Orinoco Delta are part of a regional belt of soft sediment deformation and diapirism that formed in response to rapid foredeep sedimentation and subsequent tectonic compression along the Caribbean-South American plate boundary. Field studies of five mud volcanoes show that such structures consist of a central mound covered by active and inactive vents. Inactive vents and mud flows are densely vegetated, whereas active vents are sparsely vegetated. Four out of the five mud volcanoes studied are currently active. Orinoco mud flows consist of mud and clayey silt matrix surrounding lithic clasts of varying composition. Preliminary analysis suggests that the mud volcano sediment is derived from underlying Miocene and Pliocene strata. Hydrocarbon seeps are associated with several of the active mud volcanoes. Orinoco mud volcanoes overlie the crest of a mud-diapir-cored anticline located along the axis of the Eastern Venezuelan Basin. Faulting along the flank of the Pedernales mud volcano suggests that fluidized sediment and hydrocarbons migrate to the surface along faults produced by tensional stresses along the crest of the anticline. Orinoco mud volcanoes highlight the proximity of this major delta to an active plate margin and the importance of tectonic influences on its development. Evaluation of the Orinoco Delta mud volcanoes and those elsewhere indicates that these features are important indicators of compressional tectonism along deformation fronts of plate margins. ?? 2001 Elsevier Science B.V. All rights reserved.

  19. July 1973 ground survey of active 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. Ground survey has shown that thermal anomalies of various sizes associated with volcanic activity at several Central American volcanoes should be detectable from Skylab. Anomalously hot areas of especially large size (greater than 500 m in diameter) are now found at Santiaguito and Pacaya volcanoes in Guatemala and San Cristobal in Nicaragua. Smaller anomalous areas are to be found at least seven other volcanoes. This report is completed after ground survey of eleven volcanoes and ground-based radiation thermometry mapping at these same points.

  20. Volcano Deformation and Modeling on Active Volcanoes in the Philippines from ALOS InSAR Time Series

    NASA Astrophysics Data System (ADS)

    Morales Rivera, Anieri M.; Amelung, Falk; Eco, Rodrigo

    2015-05-01

    Bulusan, Kanlaon, and Mayon volcanoes have erupted over the last decade, and Taal caldera showed signs of volcanic unrest within the same time range. Eruptions at these volcanoes are a threat to human life and infrastructure, having over 1,000,000 people living within 10 km from just these 4 volcanic centers. For this reason, volcano monitoring in the Philippines is of extreme importance. We use the ALOS-1 satellite from the Japanese Aerospace Exploration Agency (JAXA) to make an InSAR time series analysis over Bulusan, Kanlaon, Mayon, and Taal volcanoes for the 2007-2011 period. Time-dependent deformation was detected at all of the volcanoes. Deformation related to changes in pressurization of the volcanic systems was found on Taal caldera and Bulusan volcanoes, with best fitting Mogi sources located at half-space depths of 3.07 km and 0.5 km respectively.

  1. Alaska Volcano Observatory Seismic Network Data Availability

    NASA Astrophysics Data System (ADS)

    Dixon, J. P.; Haney, M. M.; McNutt, S. R.; Power, J. A.; Prejean, S. G.; Searcy, C. K.; Stihler, S. D.; West, M. E.

    2009-12-01

    The Alaska Volcano Observatory (AVO) established in 1988 as a cooperative program of the U.S. Geological Survey, the Geophysical Institute at the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, monitors active volcanoes in Alaska. Thirty-three volcanoes are currently monitored by a seismograph network consisting of 193 stations, of which 40 are three-component stations. The current state of AVO’s seismic network, and data processing and availability are summarized in the annual AVO seismological bulletin, Catalog of Earthquake Hypocenters at Alaska Volcanoes, published as a USGS Data Series (most recent at http://pubs.usgs.gov/ds/467). Despite a rich seismic data set for 12 VEI 2 or greater eruptions, and over 80,000 located earthquakes in the last 21 years, the volcanic seismicity in the Aleutian Arc remains understudied. Initially, AVO seismic data were only provided via a data supplement as part of the annual bulletin, or upon request. Over the last few years, AVO has made seismic data more available with the objective of increasing volcano seismic research on the Aleutian Arc. The complete AVO earthquake catalog data are now available through the annual AVO bulletin and have been submitted monthly to the on-line Advanced National Seismic System (ANSS) composite catalog since 2008. Segmented waveform data for all catalog earthquakes are available upon request and efforts are underway to make this archive web accessible as well. Continuous data were first archived using a tape backup, but the availability of low cost digital storage media made a waveform backup of continuous data a reality. Currently the continuous AVO waveform data can be found in several forms. Since late 2002, AVO has burned all continuous waveform data to DVDs, as well as storing these data in Antelope databases at the Geophysical Institute. Beginning in 2005, data have been available through a Winston Wave Server housed at the USGS in

  2. Degassing Processes at Persistently Active Explosive Volcanoes

    NASA Astrophysics Data System (ADS)

    Smekens, Jean-Francois

    Among volcanic gases, sulfur dioxide (SO2) is by far the most commonly measured. More than a monitoring proxy for volcanic degassing, SO 2 has the potential to alter climate patterns. Persistently active explosive volcanoes are characterized by short explosive bursts, which often occur at periodic intervals numerous times per day, spanning years to decades. SO 2 emissions at those volcanoes are poorly constrained, in large part because the current satellite monitoring techniques are unable to detect or quantify plumes of low concentration in the troposphere. Eruption plumes also often show high concentrations of ash and/or aerosols, which further inhibit the detection methods. In this work I focus on quantifying volcanic gas emissions at persistently active explosive volcanoes and their variations over short timescales (minutes to hours), in order to document their contribution to natural SO2 flux as well as investigate the physical processes that control their behavior. In order to make these measurements, I first develop and assemble a UV ground-based instrument, and validate it against an independently measured source of SO2 at a coal-burning power plant in Arizona. I establish a measurement protocol and demonstrate that the instrument measures SO 2 fluxes with < 20 % error. Using the same protocol, I establish a record of the degassing patterns at Semeru volcano (Indonesia), a volcano that has been producing cycles of repeated explosions with periods of minutes to hours for the past several decades. Semeru produces an average of 21-71 tons of SO2 per day, amounting to a yearly output of 8-26 Mt. Using the Semeru data, along with a 1-D transient numerical model of magma ascent, I test the validity of a model in which a viscous plug at the top of the conduit produces cycles of eruption and gas release. I find that it can be a valid hypothesis to explain the observed patterns of degassing at Semeru. Periodic behavior in such a system occurs for a very narrow range

  3. Analyzing Sulfur Dioxide Emissions of Nyamuragira Volcano

    NASA Astrophysics Data System (ADS)

    Guth, A. L.; Bluth, G. J.; Carn, S. A.

    2002-05-01

    Nyamuragira volcano, located in the Democratic Republic of Congo, is Africa's most active volcano, having erupted 13 times (every 1-3 years) since 1980. The eruption frequency, and the large amounts of sulfur dioxide emitted by this rift volcano, may produce a significant impact on the global sulfur budget. In this project we are attempting to quantify the sulfur dioxide emissions from this volcano over the past 20+ years using satellite data. Since 1978, satellites carrying NASA's Total Ozone Mapping Spectrometer (TOMS) instruments have been orbiting the earth collecting atmospheric data. These instruments use six wavelength bands located within the ultraviolet spectrum to measure solar irradiance and the energy reflected and backscattered by the Earth's surface and atmosphere. Sunlit planetary coverage is provided once per day by TOMS data. The spatial resolution of these satellites varies from 24 km (Earth Probe, 1996-1997, but raised to 39 km from 1997 to present) to 62 km (Meteor-3, 1991-1994). Nimbus-7, the satellite operating for the longest span of time (1978-1993), had a nadir footprint of 50 km. The (instantaneous) mass retrievals of sulfur dioxide cloud masses are derived using several different image processing schemes and net tonnages are calculated using a background correction. Volcanic activity associated with this volcano typically consists of long term (weeks to months), and often continuous, effusive emissions. Work to date has discovered over 120 days in which sulfur dioxide plumes were observed from the 13 eruptions (ranging from a minimum of one day to a maximum of 32 days). Most (82%) of the sulfur dioxide clouds measured are relatively low-level, below 100 kilotonnes (kt); 16% of the emissions are between 100 and 1000 kt, and 1.5% were measured to have more than 1000 kt. Current work is focusing on deriving net emission fluxes, integrating the TOMS instantaneous measurements of relatively continuous emission activity. The eruptive activity

  4. Growth and degradation of Hawaiian volcanoes: Chapter 3 in Characteristics of Hawaiian volcanoes

    USGS Publications Warehouse

    Clague, David A.; Sherrod, David R.

    2014-01-01

    Large Hawaiian volcanoes can persist as islands through the rapid subsidence by building upward rapidly enough. But in the long run, subsidence, coupled with surface erosion, erases any volcanic remnant above sea level in about 15 m.y. One consequence of subsidence, in concert with eustatic changes in sea level, is the drowning of coral reefs that drape the submarine flanks of the actively subsiding volcanoes. At least six reefs northwest of the Island of Hawai‘i form a stairstep configuration, the oldest being deepest.

  5. The ~ 2000 yr BP Jumento volcano, one of the youngest edifices of the Chichinautzin Volcanic Field, Central Mexico

    NASA Astrophysics Data System (ADS)

    Arce, J. L.; Muñoz-Salinas, E.; Castillo, M.; Salinas, I.

    2015-12-01

    The Chichinautzin Volcanic Field is situated at the southern limit of the Basin of Mexico and the Metropolitan area of Mexico City, the third most populated city around the world. The Chichinautzin Volcanic field holds more than 220 monogenetic volcanoes. Xitle is the youngest of these with an estimated age of 1.6 ky BP. Xitle's eruptive activity took place during the Mesoamerican Mexican Pre-classic period and is related to the destruction of Cuicuilco Archaeological Site, the oldest civilization known in Central Mexico. However, there are still several regional cones that have not been dated. Based on 14C ages, stratigraphic and geomorphologic criteria, we conclude that the Jumento volcano, located to the west of Xitle, is one of the youngest cones of the Chichinautzin Volcanic Field. The Jumento volcano has a basaltic andesite composition, and its eruptive activity was initially hydromagmatic, followed by Strombolian and finally effusive events occurred recorded through: (1) a sequence of hydromagmatic pyroclastic surges and ashfall layers emplaced at a radius of > 5 km from the crater with charcoal fragments at its base; this activity built the Jumento's cone with slopes of 32°; and (2) lava flows that breached the southern part of the cone and flowed for up to 2.5 km from the vent. The resulting 14C ages for this volcano yielded a maximum age of ~ 2 ky BP. Morphometric analysis indicates that the state of degradation of Jumento cone is similar to the Xitle, suggesting that the Jumento could be in the state of degradation of a volcanic structure of similar age or younger adding credence to the probable radiocarbon age of ~ 2 ky BP for the Jumento edifice.

  6. Pattern recognition applied to seismic signals of Llaima volcano (Chile): An evaluation of station-dependent classifiers

    NASA Astrophysics Data System (ADS)

    Curilem, Millaray; Huenupan, Fernando; Beltrán, Daniel; San Martin, Cesar; Fuentealba, Gustavo; Franco, Luis; Cardona, Carlos; Acuña, Gonzalo; Chacón, Max; Khan, M. Salman; Becerra Yoma, Nestor

    2016-04-01

    Automatic pattern recognition applied to seismic signals from volcanoes may assist seismic monitoring by reducing the workload of analysts, allowing them to focus on more challenging activities, such as producing reports, implementing models, and understanding volcanic behaviour. In a previous work, we proposed a structure for automatic classification of seismic events in Llaima volcano, one of the most active volcanoes in the Southern Andes, located in the Araucanía Region of Chile. A database of events taken from three monitoring stations on the volcano was used to create a classification structure, independent of which station provided the signal. The database included three types of volcanic events: tremor, long period, and volcano-tectonic and a contrast group which contains other types of seismic signals. In the present work, we maintain the same classification scheme, but we consider separately the stations information in order to assess whether the complementary information provided by different stations improves the performance of the classifier in recognising seismic patterns. This paper proposes two strategies for combining the information from the stations: i) combining the features extracted from the signals from each station and ii) combining the classifiers of each station. In the first case, the features extracted from the signals from each station are combined forming the input for a single classification structure. In the second, a decision stage combines the results of the classifiers for each station to give a unique output. The results confirm that the station-dependent strategies that combine the features and the classifiers from several stations improves the classification performance, and that the combination of the features provides the best performance. The results show an average improvement of 9% in the classification accuracy when compared with the station-independent method.

  7. Fire in Southern Greece

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The last major fire in southern Greece was brought under control this weekend, but not until over 469,000 acres of mostly forest and farmland were destroyed. An estimated 4000 people lost their homes, and over 60 deaths were reported. These were the worst fires ever to occur in Greece. In this Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image acquired September 4 over the western coast of the Peloponnesus Peninsula, burned areas appear in dark red, and unburned vegetation is green. The area includes the ancient site of Olympia, the site of the Olympic Games in classical times. The fires came within 2 kilometers (1.2 miles) of the archaeological site, but spared it.

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

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

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 56.4 by

  8. Volcanoes and ENSO in millennium simulations: global impacts and regional reconstructions in East Asia

    NASA Astrophysics Data System (ADS)

    Zhang, Dan; Blender, Richard; Fraedrich, Klaus

    2013-02-01

    The impacts and cooperative effects of volcanic eruptions and ENSO (El Niño/Southern Oscillation) are analyzed in a millennium simulation for 800-2005 AD using the earth system model (ESM) ECHAM5/MPIOM/JSBACH subject to anthropogenic and natural forcings. The simulation comprises two ensembles, a first with weak (E1, five members) and a second with strong (E2, three members) variability total solar irradiance. In the analysis, the 21 most intense eruptions are selected in each ensemble member. Volcanoes with neutral ENSO states during two preceding winters cause a global cooling in the year after eruptions up to -2.5°C. The nonsignificant positive values in the tropical Pacific Ocean indicate an El Niño-like warming. In the winter after an eruption, warming is mainly found in the Arctic Ocean and the Bering Sea in E2 warming extends to Siberia and central Asia. The recovery times for the volcano-induced cooling (average for 31 eruptions) vary globally between 1 and 12 years. There is no significant increase of El Niño events after volcanic eruptions in both ensembles. The simulated temperature and the drought indices are compared with corresponding reconstructions in East Asia. Volcanoes cause a dramatic cooling in west China (-2°C) and a drought in East China during the year after the eruption. The reconstructions show similar cooling patterns with smaller magnitudes and confirm the dryness in East China. Without volcanoes, El Niño events reduce summer precipitation in the North, while South China becomes wetter; La Niña events cause opposite effects. El Niño events in the winters after eruptions compensate the cooling caused by volcanoes in most regions of China (consistent with reconstructions), while La Niña events intensify the cooling (up to -2.5°C). The simulated and reconstructed drought indices show tripole patterns which are altered by El Niño events. The simulated impact of the Tambora eruption in 1815, which caused the "year without summer

  9. Latest Isopach Mapping of Holocene Rhyolitic Tephras at Medicine Lake Volcano, Northern California

    NASA Astrophysics Data System (ADS)

    Ramsey, D. W.; Miller, C. D.

    2011-12-01

    Medicine Lake Volcano, located in the southern Cascades ~55 km east-northeast of Mount Shasta, is a large rear-arc, shield-shaped volcano with an eruptive history spanning nearly 500,000 years. The most recent eruptions at Medicine Lake Volcano are the late Holocene explosive to effusive events at Glass Mountain (~950 yr) and Little Glass Mountain (~1000 yr), which began as sub-Plinian to Plinian eruptions of rhyolite pumice from fissure vents, and culminated in the rhyolite-dacite of Glass Mountain and the rhyolite of Little Glass Mountain. Vents for these eruptions lie along fissures located 15 km apart on opposite sides of the summit caldera of Medicine Lake Volcano. Previous mapping of these deposits by Fisher (1964) and by Heiken (1978) showed a strong northeast-southwest trend of the Little Glass Mountain tephras. Our latest isopach maps of primary tephra deposits from the Glass Mountain and Little Glass Mountain eruptions are based on more extensive fieldwork and on a different interpretation of Little Glass Mountain tephras than previous work Our work shows a strong northeast-southwest trend of the Little Glass Mountain tephras and extends the deposit further in the direction of Mount Shasta, where C. D. Miller found individual lapilli from the Little Glass Mountain eruption. This plume direction is unusual given the dominant westerly wind directions in the region. Winds blow from the northeast less than 2 percent of the time in a typical year. Our field investigations have also shown that Little Glass Mountain tephras consist of two distinct deposits: a coarse, white, pumiceous deposit erupted from Little Glass Mountain and found along the strong northeast-southwest trend; and a fine-grained, salmon-colored tephra erupted from fissure vents north of Little Glass Mountain around Crater Glass Flow and found to the north and east. Field relationships show that the salmon-colored tephra was erupted just prior to the white, pumiceous tephra, and that its fine

  10. Seismic precursors of the July 29, 2008 explosions at Soufriere Hills Volcano

    NASA Astrophysics Data System (ADS)

    de Angelis, S.

    2009-12-01

    Soufriere Hills Volcano (SHV) is an andesitic lava dome complex located on the southern part of the Island of Montserrat, in the North section of the Lesser Antilles arc. From July, 1995 to present, SHV has been in a nearly continuous state of eruption characterized by cycles of lava dome building and collapse, interspersed by periods of temporary quiescence. The last such period of quiescence started in April 2007, and lasted about one year. Between April 2007 and May 2008, the activity at SHV was limited to gradual erosion of the lava dome. Earthquake rates were the lowest since the start of the eruption in 1995. During this period the SHV seismic network recorded almost exclusively surface signals related to rock-falls and small pyroclastic flows. Between April 25 and May 2, 2008, heightened volcano-tectonic seismicity was recorded. Surface activity picked up between May 13 and July 26 with at least eight small explosions from an active vent situated on the South-West sector of the dome. A dramatic increase in seismicity was recorded on July 26. Earthquake rates were observed to increase rapidly, and the character of seismicity evolved from high to low-frequency as time progressed. The Montserrat Volcano Observatory seismic network detected more than 1500 earthquakes during July 26-28, 277 large enough to be located at depths between 0 and 3.4 km underneath the volcano. By late afternoon on July 28, seismic activity had returned to nearly background levels. Following few hours of virtually no seismic activity, and without any further warning, a large vulcanian explosion occurred at approximately 03:30 a.m. UTC (Coordinated Universal Time). The explosion generated a large ash column and pyroclastic flows with run-out distances up to 1.5 km. Remarkably, many of the events recorded during July 26-27 exhibited striking waveform similarity. Observations of repeating events have been reported at many volcanoes, and various interpretations put forward on their source

  11. New insights on Panarea volcano from terrestrial, marine and airborne data

    NASA Astrophysics Data System (ADS)

    Anzidei, Marco

    2010-05-01

    The Panarea volcano belongs to the Aeolian arc system and its activity, which recently produced impacts on the environment as well as on human settlements, is known since historical times. This volcano, which includes Panarea island and its archipelago, is the emergent portion of submarine stratovolcano more than 2000 m high and 20 Km across. In November 2002 a submarine gas eruption started offshore 3 Km east of Panarea on top of a shallow rise of 2.3 km2 surrounded by the islets of Lisca Bianca, Bottaro and Lisca Nera. This event has posed new concern on a volcano generally considered extinct. Soon after the submarine eruption, this area has been surveyed under multidisciplinary programs funded by the Italian Department of the Civil Protection and INGV. Monitoring programs included subaerial and sea bottom DEM of Panarea volcano by merging aerial digital photogrammetry, aerial laser scanning and multibeam bathymetry. A GPS ground deformation network (PANANET) was designed, set up and measured during time span December 2002 - October 2007. GPS data show rates of motion and strain values typical of volcanic areas which are in agreement with the NE-SW and NW-SE tectonic systems. The latter coincide with the main pathways for the upwelling of hydrothermal fluids. GPS data inferred a pre-event uplift followed by a general subsidence and shortening across the area that could be interpreted as the response to the surface of the inflation and deflation of the hydrothermal system reservoir which is progressively reducing its pressure after the 2002 gas eruption. Magnetic and gravimetric data depict the deep and shallow structure of the volcano. From geochemical surveys were calculated energetic conditions at craters. Data were coupled with the computed physic-chemical state of the fluids at the level of the deep reservoir and provided the boundary conditions of the occurred event, and suggesting that a low-energy explosion was responsible for producing the craters at the

  12. Southern Crater

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03583 Southern Crater

    This crater is located south of Agassiz Crater. It is likely that the polar freeze/thaw/frost cycle is responsible for unusual appearance of the ejecta region around the crater.

    Image information: VIS instrument. Latitude 76.2S, Longitude 247.8E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  13. ASTER Observations of 2000-2007 Thermal Features at Pavlof Volcano and Mt. Hague (Emmons Lake Volcanic Center), Alaska

    NASA Astrophysics Data System (ADS)

    Wessels, R. L.; Schneider, D.; Ramsey, M.; Mangan, M. T.

    2007-12-01

    Emmons Lake Volcanic Center (ELVC) is a 15 km by 30 km area of nested calderas, stratovolcanoes, lava domes, hyaloclastite rings, and cinder cones aligned along the arc axis. Pavlof Volcano is the most active volcano along the ELVC, with more than 40 historic eruptions since 1790. The most recent eruption of Pavlof Volcano began in August 2007 after almost 11 years of quiescence. Mount Hague is a prominent intracaldera vent with no known historical eruptions that lies approximately 7 kilometers to the southwest of Pavlof. The southern crater of Mount Hague commonly fluctuates between a crater-filling lake to a dry crater floor with vigorously steaming fumaroles. Mount Hague has another fumarole field on the southeast flank at nearly the same elevation as the crater floor. To better document the behavior of persistent thermal features at these remote volcanoes, we have compiled temperature and dimension data using a seven-year long time series of satellite data. Over 25 daytime and 40 nighttime clear thermal infrared (TIR) images (90 m resolution) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have recorded variations in the thermal activity at both volcanic vents since July 2000. All cloud-free ASTER TIR observations document persistent low- temperature features at both Pavlof Volcano and Mount Hague during this period. The size and temperature of each thermal feature varies throughout the study period. The data show that the 2518 m summit of Pavlof Volcano is occasionally snow-free in early summer whereas neighboring peaks at lower elevations are still snow-clad. FLIR data acquired near the summit of Pavlof in 2004 show that the majority of warm ground was at 20°C to 40°C. These warm areas commonly persist snow-free into the winter. Temperature variations observed at Mt Hague crater usually correlate to the size of the ephemeral crater lake. As the lake grows, the pixel-integrated ASTER TIR temperature increases. Measurements

  14. Spectral characteristics of volcano-tectonic earthquake swarms in Nevado del Ruiz Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Londono, John M.; Sudo, Yasuaki

    2001-12-01

    Spectral analyses for volcano-tectonic earthquakes were carried out at Nevado del Ruiz Volcano (NRV) for the period 1985-1996 for several earthquake swarms around the volcano, named North, East, West, South and Crater swarm zones. Important spectral peaks for each earthquake swarm zone were found by counting the number of spectra that had the same spectral peaks. Each swarm zone showed some characteristic peaks, which could help to differentiate between them; however, the most important peaks were similar for all the zones. These results suggest that the earthquake swarms at NRV were influenced directly by the source (activity of the volcano) and could also be influenced by the site effect. Some temporal changes were observed in spectral parameters such as a change in the frequency contents in almost all the swarm zones, and the frequency of the P-waves in the West earthquake swarm zone. Before the eruptions on November 13, 1985 and September 1, 1989, P-waves showed low frequencies (1-2 Hz) at the West earthquake swarm. After the eruptions, the frequencies of P increased (2-4 Hz). This fact showed that changes (decreasing of frequencies) in the spectra of P-waves at the West earthquake swarm could help in the monitoring of volcanic activity at NRV. This swarm zone seems to be related directly with the most important volcanic crises that have occurred. This suggests that the West swarm zone should be monitored in more detail in the future.

  15. Preliminary Volcano-Hazard Assessment for Gareloi Volcano, Gareloi Island, Alaska

    USGS Publications Warehouse

    Coombs, Michelle L.; McGimsey, Robert G.; Browne, Brandon L.

    2008-01-01

    Gareloi Volcano (178.794 degrees W and 51.790 degrees N) is located on Gareloi Island in the Delarof Islands group of the Aleutian Islands, about 2,000 kilometers west-southwest of Anchorage and about 150 kilometers west of Adak, the westernmost community in Alaska. This small (about 8x10 kilometer) volcano has been one of the most active in the Aleutians since its discovery by the Bering expedition in the 1740s, though because of its remote location, observations have been scant and many smaller eruptions may have gone unrecorded. Eruptions of Gareloi commonly produce ash clouds and lava flows. Scars on the flanks of the volcano and debris-avalanche deposits on the adjacent seafloor indicate that the volcano has produced large landslides in the past, possibly causing tsunamis. Such events are infrequent, occurring at most every few thousand years. The primary hazard from Gareloi is airborne clouds of ash that could affect aircraft. In this report, we summarize and describe the major volcanic hazards associated with Gareloi.

  16. Receiver Function Analyses of Uturuncu Volcano, Bolivia and Lastarria/Cordon Del Azufre Volcanoes, Chile

    NASA Astrophysics Data System (ADS)

    Mcfarlin, H. L.; Christensen, D. H.; Thompson, G.; McNutt, S. R.; Ryan, J. C.; Ward, K. M.; Zandt, G.; West, M. E.

    2014-12-01

    Uturuncu Volcano and a zone between Lastarria and Cordon del Azufre Volcanoes (also calledLazufre), have seen much attention lately because of significant and rapid inflation of one to twocentimeters per year over large areas. Uturuncu is located near the Bolivian-Chilean border, andLazufre is located near the Chilean-Argentine border. The PLUTONS Project deployed 28broadband seismic stations around Uturuncu Volcano, from April 2009 to Octobor 2012, and alsodeployed 9 stations around Lastarria and Cordon del Azufre volcanoes, from November, 2011 toApril 2013. Teleseismic receiver functions were generated using the time-domain iterativedeconvolution algorithm of Ligorria and Ammon (1999) for each volcanic area. These receiverfunctions were used to better constrain the depths of magma bodies under Uturuncu and Lazufre,as well as the ultra low velocity layer within the Altiplano-Puna Magma Body (APMB). Thelow velocity zone under Uturuncu is shown to have a top around 10 km depth b.s.l and isgenerally around 20 km thick with regional variations. Tomographic inversion shows a well resolved,near vertical, high Vp/Vs anomaly directly beneath Uturuncu that correlates well with adisruption in the receiver function results; which is inferred to be a magmatic intrusion causing alocal thickening of the APMB. Preliminary results at Lazufre show the top of a low velocityzone around 5-10 km b.s.l with a thickness of 15-30 km.

  17. SO2 camera measurements at Lastarria volcano and Lascar volcano in Chile

    NASA Astrophysics Data System (ADS)

    Lübcke, Peter; Bobrowski, Nicole; Dinger, Florian; Klein, Angelika; Kuhn, Jonas; Platt, Ulrich

    2015-04-01

    The SO2 camera is a remote-sensing technique that measures volcanic SO2 emissions via the strong SO2 absorption structures in the UV using scattered solar radiation as a light source. The 2D-imagery (usually recorded with a frame rate of up to 1 Hz) allows new insights into degassing processes of volcanoes. Besides the large advantage of high frequency sampling the spatial resolution allows to investigate SO2 emissions from individual fumaroles and not only the total SO2 emission flux of a volcano, which is often dominated by the volcanic plume. Here we present SO2 camera measurements that were made during the CCVG workshop in Chile in November 2014. Measurements were performed at Lastarria volcano, a 5700 m high stratovolcano and Lascar volcano, a 5600 m high stratovolcano both in northern Chile on 21 - 22 November, 2014 and on 26 - 27 November, 2014, respectively. At both volcanoes measurements were conducted from a distance of roughly 6-7 km under close to ideal conditions (low solar zenith angle, a very dry and cloudless atmosphere and an only slightly condensed plume). However, determination of absolute SO2 emission rates proves challenging as part of the volcanic plume hovered close to the ground. The volcanic plume therefore is in front of the mountain in our camera images. An SO2 camera system consisting of a UV sensitive CCD and two UV band-pass filters (centered at 315 nm and 330 nm) was used. The two band-pass filters are installed in a rotating wheel and images are taken with both filter sequentially. The instrument used a CCD with 1024 x 1024 pixels and an imaging area of 13.3 mm x 13.3 mm. In combination with the focal length of 32 mm this results in a field-of-view of 25° x 25°. The calibration of the instrument was performed with help of a DOAS instrument that is co-aligned with the SO2 camera. We will present images and SO2 emission rates from both volcanoes. At Lastarria gases are emitted from three different fumarole fields and we will attempt

  18. Volcano monitoring with an infrared camera: first insights from Villarrica Volcano

    NASA Astrophysics Data System (ADS)

    Rosas Sotomayor, Florencia; Amigo Ramos, Alvaro; Velasquez Vargas, Gabriela; Medina, Roxana; Thomas, Helen; Prata, Fred; Geoffroy, Carolina

    2015-04-01

    This contribution focuses on the first trials of the, almost 24/7 monitoring of Villarrica volcano with an infrared camera. Results must be compared with other SO2 remote sensing instruments such as DOAS and UV-camera, for the ''day'' measurements. Infrared remote sensing of volcanic emissions is a fast and safe method to obtain gas abundances in volcanic plumes, in particular when the access to the vent is difficult, during volcanic crisis and at night time. In recent years, a ground-based infrared camera (Nicair) has been developed by Nicarnica Aviation, which quantifies SO2 and ash on volcanic plumes, based on the infrared radiance at specific wavelengths through the application of filters. Three Nicair1 (first model) have been acquired by the Geological Survey of Chile in order to study degassing of active volcanoes. Several trials with the instruments have been performed in northern Chilean volcanoes, and have proven that the intervals of retrieved SO2 concentration and fluxes are as expected. Measurements were also performed at Villarrica volcano, and a location to install a ''fixed'' camera, at 8km from the crater, was discovered here. It is a coffee house with electrical power, wifi network, polite and committed owners and a full view of the volcano summit. The first measurements are being made and processed in order to have full day and week of SO2 emissions, analyze data transfer and storage, improve the remote control of the instrument and notebook in case of breakdown, web-cam/GoPro support, and the goal of the project: which is to implement a fixed station to monitor and study the Villarrica volcano with a Nicair1 integrating and comparing these results with other remote sensing instruments. This works also looks upon the strengthen of bonds with the community by developing teaching material and giving talks to communicate volcanic hazards and other geoscience topics to the people who live "just around the corner" from one of the most active volcanoes

  19. Nyiragongo volcano, Congo, Anaglyph, SRTM / Landsat

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Nyiragongo volcano in the Congo erupted on January 17, 2002, and subsequently sent streams of lava into the city of Goma on the north shore of Lake Kivu. More than 100 people were killed, more than 12,000 homes were destroyed, and hundreds of thousands were forced to flee the broader community of nearly half a million people. This stereoscopic (anaglyph) visualization combines a Landsat satellite image and an elevation model from the Shuttle Radar Topography Mission (SRTM) to provide a view of the volcano, the city of Goma, and surrounding terrain.

    Nyiragongo is the steep volcano to the lower right of center, Lake Kivu is at the bottom, and the city of Goma is located along the northeast shore (bottom center). Nyiragongo peaks at about 3,470 meters (11,380 feet) elevation and reaches almost exactly 2,000 meters (6,560 feet) above Lake Kivu. The shorter but broader Nyamuragira volcano appears to the upper left of Nyiragongo.

    Goma, Lake Kivu, Nyiragongo, Nyamuragira and other nearby volcanoes sit within the East African Rift Valley, a zone where tectonic processes are cracking, stretching, and lowering the Earth's crust. The cliff at the top center of the image is the western edge of the rift. Volcanic activity is common in the rift, and older but geologically recent lava flows (dark in this depiction) are particularly apparent on the flanks of the Nyamuragira volcano.

    This anaglyph was produced by first shading an elevation model from data acquired by the Shuttle Radar Topography Mission and blending it with a single band of a Landsat scene. The stereoscopic effect was then created by generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and the right eye with a blue filter.

    The Landsat image used here was acquired on December 11, 2001, about a month before

  20. Lahar Hazard Modeling at Tungurahua Volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Sorensen, O. E.; Rose, W. I.; Jaya, D.

    2003-04-01

    Tungurahua Volcano (Lat. 01^o28'S; Long. 78^o27'W), located in the central Ecuadorian Andes, is an active edifice that rises more than 3 km above surrounding topography. Since European settlement in 1532, Tungurahua has experienced four major eruptive episodes: 1641-1646, 1773-1781, 1886-1888 and 1916-1918 (Hall et al, JVGR V91; p1-21, 1999). In September 1999, Tungurahua began a new period of activity that continues to the present. During this time, the volcano has erupted daily, depositing ash and blocks on its steep flanks. A pattern of continuing eruptions, coupled with rainfall up to 28 mm in a 6 hour period (rain data collected in Baños at 6-hr intervals, 3000 meters below Tungurahua’s summit), has produced an environment conducive to lahar mobilization. Tungurahua volcano presents an immediate hazard to the town of Baños, an important tourist destination and cultural center with a population of about 25,000 residents located 8 km from the crater. During the current eruptive episode, lahars have occurred as often as 3 times per week on the northern and western slopes of the volcano. Consequently, the only north-south trending highway on the west side of Tungurahua has been completely severed at the intersection of at least ten drainages, where erosion has exceeded 10 m since 1999. The La Pampa quebrada, located 1 km west of Baños, is the most active of Tungurahua's drainages. At this location, where the slope is moderate, lahars continue to inundate the only highway linking Baños to the Pan American Highway. Because of steep topography, the conventional approach of measuring planimetric inundation areas to determine the scale of lahars could not be employed. Instead, cross sections were measured in the channels using volume/cross-sectional inundation relationships determined by (Iverson et al, GSABull V110; no. 8, p972-984, 1998). After field observations of the lahars, LAHARZ, a program used in a geographic information system (GIS) to objectively map

  1. Imaging magma plumbing beneath Askja volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Greenfield, Tim; White, Robert S.

    2015-04-01

    Volcanoes during repose periods are not commonly monitored by dense instrumentation networks and so activity during periods of unrest is difficult to put in context. We have operated a dense seismic network of 3-component, broadband instruments around Askja, a large central volcano in the Northern Volcanic Zone, Iceland, since 2006. Askja last erupted in 1961, with a relatively small basaltic lava flow. Since 1975 the central caldera has been subsiding and there has been no indication of volcanic activity. Despite this, Askja has been one of the more seismically active volcanoes in Iceland. The majority of these events are due to an extensive geothermal area within the caldera and tectonically induced earthquakes to the northeast which are not related to the magma plumbing system. More intriguing are the less numerous deeper earthquakes at 12-24km depth, situated in three distinct areas within the volcanic system. These earthquakes often show a frequency content which is lower than the shallower activity, but they still show strong P and S wave arrivals indicative of brittle failure, despite their location being well below the brittle-ductile boundary, which, in Askja is ~7km bsl. These earthquakes indicate the presence of melt moving or degassing at depth while the volcano is not inflating, as only high strain rates or increased pore fluid pressures would cause brittle fracture in what is normally an aseismic region in the ductile zone. The lower frequency content must be the result of a slower source time function as earthquakes which are both high frequency and low frequency come from the same cluster, thereby discounting a highly attenuating lower crust. To image the plumbing system beneath Askja, local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. Travel-time tables were created using a finite difference technique and the residuals were used to solve simultaneously for both the earthquake locations

  2. Space Radar Image of Kiluchevskoi, Volcano, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image of the area of Kliuchevskoi volcano, Kamchatka, Russia, which began to erupt on September 30, 1994. Kliuchevskoi is the blue triangular peak in the center of the image, towards the left edge of the bright red area that delineates bare snow cover. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 88th orbit on October 5, 1994. The image shows an area approximately 75 kilometers by 100 kilometers (46 miles by 62 miles) that is centered at 56.07 degrees north latitude and 160.84 degrees east longitude. North is toward the bottom of the image. The radar illumination is from the top of the image. The Kamchatka volcanoes are among the most active volcanoes in the world. The volcanic zone sits above a tectonic plate boundary, where the Pacific plate is sinking beneath the northeast edge of the Eurasian plate. The Endeavour crew obtained dramatic video and photographic images of this region during the eruption, which will assist scientists in analyzing the dynamics of the recent activity. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). In addition to Kliuchevskoi, two other active volcanoes are visible in the image. Bezymianny, the circular crater above and to the right of Kliuchevskoi, contains a slowly growing lava dome. Tolbachik is the large volcano with a dark summit crater near the upper right edge of the red snow covered area. The Kamchatka River runs from right to left across the bottom of the image. The current eruption of Kliuchevskoi included massive ejections of gas, vapor and ash, which reached altitudes of 15,000 meters (50,000 feet). Melting snow mixed with volcanic ash triggered mud flows on the

  3. Interpretation and utility of infrasonic records from erupting volcanoes

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Aster, R. C.; Ruiz, M. C.; Malone, S. D.; McChesney, P. J.; Lees, J. M.; Kyle, P. R.

    2003-02-01

    In the most basic seismo-acoustic studies at volcanoes, infrasound monitoring enables differentiation between sub-surface seismicity and the seismicity associated with gas release. Under optimal conditions, complicated degassing signals can be understood, relative explosion size can be assessed, and variable seismo-acoustic energy partitioning can be interpreted. The extent to which these points may be investigated depends upon the quality of the infrasonic records (a function of background wind noise, microphone sensitivity, and microphone array geometry) and the type of activity generated by the volcano (frequency of explosions, bandwidth of the signals, and coupling efficiency of the explosion to elastic energy). To illustrate the features, benefits, and limitations of infrasonic recordings at volcanoes, we showcase acoustic and seismic records from five volcanoes characterized by explosive degassing. These five volcanoes (Erebus in Antarctica, Karymsky in Russia, and Sangay, Tungurahua, and Pichincha in Ecuador) were the focus of seismo-acoustic experiments between 1997 and 2000. Each case study provides background information about the volcanic activity, an overview of visual observations during the period of monitoring, and examples of seismo-acoustic data. We discuss the benefits and utility of the infrasound study at each respective volcano. Finally, we compare the infrasound records and eruptive activity from these volcanoes with other volcanoes that have been the focus of previous seismo-acoustic experiments.

  4. Volcano Monitor: Autonomous Triggering of In-Situ Sensors

    NASA Technical Reports Server (NTRS)

    Behar, Alberto; Davies, Ashley; Tran, Daniel Q.; Boudreau, Kate; Cecava, Johanna

    2009-01-01

    In-situ sensors near volcanoes would be alerted by the Earth Observing-1 (EO-1) craft to take more frequent data readings. This project involves developing a sulfur-dioxide-sensing volcano monitor that will be able to transmit its readings through an Iridium modem.

  5. Kilauea Volcano, Hawaii: A search for the volcanomagnetic effect

    USGS Publications Warehouse

    Davis, P.M.; Jackson, D.B.; Field, J.; Stacey, F.D.

    1973-01-01

    Brief excursions of magnetic field differences between a base station and two satellite station magnetometers show only slight correlation with ground tilt at Kilauea Volcano. This result suggests that only transient, localized stresses occur during prolonged periods of deformation and that the volcano can support no large-scale pattern of shear stresses.

  6. Using Google Earth to Study the Basic Characteristics of Volcanoes

    ERIC Educational Resources Information Center

    Schipper, Stacia; Mattox, Stephen

    2010-01-01

    Landforms, natural hazards, and the change in the Earth over time are common material in state and national standards. Volcanoes exemplify these standards and readily capture the interest and imagination of students. With a minimum of training, students can recognize erupted materials and types of volcanoes; in turn, students can relate these…

  7. Volcano ecology: Disturbance characteristics and assembly of biological communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Volcanic eruptions are powerful expressions of Earth’s geophysical forces which have shaped and influenced ecological systems since the earliest days of life. The study of the interactions of volcanoes and ecosystems, termed volcano ecology, focuses on the ecological responses of organisms and biolo...

  8. Iceland: Grímsvötn Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Grímsvötn Volcano Injects Ash into the Stratosphere     ... p.m. local time (1730 UTC) on Saturday, May 21, 2011. The volcano, located approximately 140 miles (220 kilometers) east of the capital ...

  9. Structural map of the summit area of Kilauea Volcano, Hawaii

    SciTech Connect

    Not Available

    1982-01-01

    The map shows the faults, sets of fissures, eruptive vent lines and collapse features in the summit area of the volcano. It covers most of the USGS Kilauea Crater 7-1/2 minute quadrangle, together with parts of Volcano, Makaopuhi Crater, and Kau Desert 7-1/2 minute quadrangles. (ACR)

  10. Global data collection and the surveillance of active volcanoes

    USGS Publications Warehouse

    Ward, P.L.

    1990-01-01

    Data relay systems on existing earth-orbiting satellites provide an inexpensive way to collect environmental data from numerous remote sites around the world. This technology could be used effectively for fundamental monitoring of most of the world's active volcanoes. Such global monitoring would focus attention on the most dangerous volcanoes that are likely to significantly impact the geosphere and the biosphere. ?? 1990.

  11. Reconstructing the plumbing system of Krakatau volcano

    NASA Astrophysics Data System (ADS)

    Troll, Valentin R.; Dahrén, Börje; Deegan, Frances M.; Jolis, Ester M.; Blythe, Lara S.; Harris, Chris; Berg, Sylvia E.; Hilton, David R.; Freda, Carmela

    2014-05-01

    Crustal contamination of ascending arc magmas is generally thought to be significant at lower- to mid-crustal magma storage levels where magmas inherit their chemical and isotopic character by blending, assimilation and differentiation [1]. Anak Krakatau, like many other volcanoes, erupts shallow-level crustal xenoliths [2], indicating a potential role for upper crustal modification and hence late-stage changes to magma rheology and thus eruptive behaviour. Distinguishing deep vs. shallow crustal assimilation processes at Krakatau, and elsewhere, is therefore crucial to understand and assess pre-eruptive magmatic conditions and their associated hazard potential. Here we report on a multi-disciplinary approach to unravel the crustal plumbing system of the persistently-active and dominantly explosive Anak Krakatau volcano [2, 3]. We employ rock-, mineral- and gas-isotope geochemistry and link these results with seismic tomography [4]. We show that pyroxene crystals formed at mid- and lower-crustal levels (9-11 km) and carry almost mantle-like isotope signatures (O, Sr, Nd, He), while feldspar crystals formed dominantly at shallow levels (< 5km) and display unequivocal isotopic evidence for late stage contamination (O, Sr, Nd). Coupled with tomographic evidence, the petrological and geochemical data place a significant element of magma-crust interaction (and hence magma storage) into the uppermost, sediment-rich crust beneath the volcano. Magma - sediment interaction in the uppermost crust offers a likely explanation for the compositional variations in recent Krakatau magmas and most probably provides extra impetus to increased explosivity at Anak Krakatau. [1] Annen, et al., 2006. J. Petrol. 47, 505-539. [2] Gardner, et al., 2013. J. Petrol. 54, 149-182. [3] Dahren, et al., 2012. Contrib. Mineral. Petrol. 163, 631-651. [4] Jaxybulatov, et al., 2011. J. Volcanol. Geoth. Res. 206, 96-105.

  12. Nyiragongo Volcano Erupts in the Congo

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  13. Monte Carlo Volcano Seismic Moment Tensors

    NASA Astrophysics Data System (ADS)

    Waite, G. P.; Brill, K. A.; Lanza, F.

    2015-12-01

    Inverse modeling of volcano seismic sources can provide insight into the geometry and dynamics of volcanic conduits. But given the logistical challenges of working on an active volcano, seismic networks are typically deficient in spatial and temporal coverage; this potentially leads to large errors in source models. In addition, uncertainties in the centroid location and moment-tensor components, including volumetric components, are difficult to constrain from the linear inversion results, which leads to a poor understanding of the model space. In this study, we employ a nonlinear inversion using a Monte Carlo scheme with the objective of defining robustly resolved elements of model space. The model space is randomized by centroid location and moment tensor eigenvectors. Point sources densely sample the summit area and moment tensors are constrained to a randomly chosen geometry within the inversion; Green's functions for the random moment tensors are all calculated from modeled single forces, making the nonlinear inversion computationally reasonable. We apply this method to very-long-period (VLP) seismic events that accompany minor eruptions at Fuego volcano, Guatemala. The library of single force Green's functions is computed with a 3D finite-difference modeling algorithm through a homogeneous velocity-density model that includes topography, for a 3D grid of nodes, spaced 40 m apart, within the summit region. The homogenous velocity and density model is justified by long wavelength of VLP data. The nonlinear inversion reveals well resolved model features and informs the interpretation through a better understanding of the possible models. This approach can also be used to evaluate possible station geometries in order to optimize networks prior to deployment.

  14. Jun Jaegyu Volcano: A Recently Discovered Alkali Basalt Volcano in Antarctic Sound, Antarctica

    NASA Astrophysics Data System (ADS)

    Hatfield, A.; Bailey, D.; Domack, E.; Brachfeld, S.; Gilbert, R.; Ishman, S.; Krahmann, G.; Leventer, A.

    2004-12-01

    Jun Jaegyu is a young volcanic construct discovered in May 2004 by researchers aboard the National Science Foundation (NSF) vessel Laurence M. Gould (LMG04-04). The volcano is located on the Antarctic continental shelf in Antarctic Sound, approximately 9 km due north of the easternmost point of Andersson Island. Swath bathymetry (NBP01-07) indicates that the volcano stands 700 meters above the seafloor, yet remains 275 meters short of the ocean surface. The seamount lies along a northwest-southeast oriented fault scarp and contains at least 1.5 km3 of volcanic rock. Video recording of the volcano's surface revealed regions nearly devoid of submarine life. These areas are associated with a thermal anomaly of up to 0.052° C higher than the surrounding ocean water. A rock dredge collected ~13 kg of material, over 80% of which was fresh volcanic rock; the remainder was glacial IRD. These observations, along with reports by mariners of discolored water in this region of Antarctic Sound, suggest that the volcano has been recently active. The basalt samples are generally angular, glassy and vesicular. Preliminary petrographic observations indicate that plagioclase, olivine, and clinopyroxene are all present as phenocryst phases, and that small (<1cm) rounded xenoliths are common. A comprehensive study of the volcano's petrography and whole-rock chemistry is currently underway. Jun Jaegyu is the northernmost volcanic center of the James Ross Island Volcanic Group (JRIVG), and the only center in this region of the Antarctic Peninsula with evidence of recent activity. It lies along the boundary between the Late Cenozoic JRIVG and the Upper Paleozoic rocks of the Trinity Peninsula Formation. While the tectonic setting of the region is complex, volcanism appears to be associated with active faults related to within-plate extension.

  15. Galactic Super-volcano in Action

    NASA Astrophysics Data System (ADS)

    2010-08-01

    A galactic "super-volcano" in the massive galaxy M87 is erupting and blasting gas outwards, as witnessed by NASA's Chandra X-ray Observatory and NSF's Very Large Array. The cosmic volcano is being driven by a giant black hole in the galaxy's center and preventing hundreds of millions of new stars from forming. Astronomers studying this black hole and its effects have been struck by the remarkable similarities between it and a volcano in Iceland that made headlines earlier this year. At a distance of about 50 million light years, M87 is relatively close to Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies. M87's location, coupled with long observations over Chandra's lifetime, has made it an excellent subject for investigations of how a massive black hole impacts its environment. "Our results show in great detail that supermassive black holes have a surprisingly good control over the evolution of the galaxies in which they live," said Norbert Werner of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the SLAC National Accelerator Laboratory, who led one of two papers describing the study. "And it doesn't stop there. The black hole's reach extends ever farther into the entire cluster, similar to how one small volcano can affect practically an entire hemisphere on Earth." The cluster surrounding M87 is filled with hot gas glowing in X-ray light, which is detected by Chandra. As this gas cools, it can fall toward the galaxy's center where it should continue to cool even faster and form new stars. However, radio observations with the Very Large Array suggest that in M87 jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the center of the galaxy and produce shock waves in the galaxy's atmosphere because of their supersonic speed. The scientists involved in this research have found the interaction of this cosmic

  16. Acoustic noise from volcanoes - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Woulff, G.; Mcgetchin, T. R.

    1976-01-01

    The paper discusses some theoretical aspects of acoustic investigation of volcanoes and describes a field experiment involving the recording, analysis, and interpretation of acoustic radiation from energetic fumaroles at Volcan Acatenango, Guatemala, during mid-January 1973. Particular attention is given to deriving information about the flow velocity of the erupting medium from acoustics as a means to study eruption dynamics. Theoretical considerations suggest that acoustic power radiated during gaseous volcanic eruptions may be related to gas exit velocity according to appropriate power laws. Eruption acoustics proves useful as a means of quantitative monitoring of volcanic activity.

  17. Lava Flows On Ascraeus Mons Volcano

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Ascraeus Mons Volcano: Like Earth, Mars has many volcanoes and volcanic features. This high-resolution view shows some of the lava flows near the summit of Ascraeus Mons, one of the three giant shield volcanoes known as the 'Tharsis Montes'. Volcanoes form when magma (molten rock) erupts out onto the surface of a planet. Based on Viking-era observations, Ascraeus Mons is considered to be one of the tallest volcanoes on Mars... its summit is more than 11 km (6.8 miles) above the surrounding plain. The summit is more than 23 km (14 miles) higher in elevation than the place where Mars Pathfinder landed in July 1997.

    Description of MOC Image: This picture shows an area that is about 20 km (12 miles) higher in elevation than the Mars Pathfinder landing site. The picture shows three main features: (1) a crater at the center-right, (2) a sinuous, discontinuous channel across the upper half, and (3) a rough and pitted, elevated surface across the lower half of the image.

    (1) Crater at center right. Distinguishing meteor craters from volcanic craters can sometimes be a challenge on Mars. This particular crater was most likely formed by meteor impact because it has a raised rim and a faint radial ejecta pattern around the outside of it. This crater is 600 m (2000 feet) across, about 3/4 the size of the famous 'Meteor Crater' near Winslow, Arizona.

    (2) Sinuous channel. The type of discontinuous channel running across the upper half of the image is sometimes referred to as a 'sinuous rille'. These are common on the volcanic plains of the Moon and among volcanoes and volcanic plains on Earth. Such a channel was once a lava tube. It is running down the middle of an old lava flow. The 'tube' looks like a 'channel' because its roof has collapsed. The discontinuous nature of this channel is the result of the collapse, or 'cave-in' of what was once the roof of the lava tube. It is common for certain types of relatively fluid lavas to form

  18. On Relations between Current Global Volcano Databases

    NASA Astrophysics Data System (ADS)

    Newhall, C. G.; Siebert, L.; Sparks, S.

    2009-12-01

    The Smithsonian’s Volcano Reference File (VRF), the database that underlies Volcanoes of the World and This Dynamic Planet, is the premier source for the “what, when, where, and how big?” of Holocene and historical eruptions. VOGRIPA (Volcanic Global Risk Identification and Analysis) will catalogue details of large eruptions, including specific phenomena and their impacts. CCDB (Collapse Caldera Database) also considers large eruptions with an emphasis on the resulting calderas. WOVOdat is bringing monitoring data from the world’s observatories into a centralized database in common formats, so that they can be searched and compared during volcanic crises and for research on preeruption processes. Oceanographic and space institutions worldwide have growing archives of volcano imagery and derivative products. Petrologic databases such as PETRODB and GEOROC offer compositions of many erupted and non-erupted magmas. Each of these informs and complements the others. Examples of interrelations include: ● Information in the VRF about individual volcanoes is the starting point and major source of background “volcano” data in WOVOdat, VOGRIPA, and petrologic databases. ● Images and digital topography from remote sensing archives offer high-resolution, consistent geospatial "base maps" for all of the other databases. ● VRF data about eruptions shows whether unrest of WOVOdat culminated in an eruption and, if yes, its type and magnitude. ● Data from WOVOdat fills in the “blanks” between eruptions in the VRF. ● VOGRIPA adds more detail to the VRF’s descriptions of eruptions, including quantification of runout distances, expanded estimated column heights and eruption impact data, and other parameters not included in the Smithsonian VRF. ● Petrologic databases can add detail to existing petrologic data of the VRF, WOVOdat, and VOGRIPA, e.g, detail needed to estimate viscosity of melt and its influence on magma and eruption dynamics ● Hazard

  19. Hawaiian Volcano Observatory 1956 Quarterly Administrative Reports

    USGS Publications Warehouse

    Nakata, Jennifer S., (compiler)

    2007-01-01

    The Hawaiian Volcano Observatory Summaries have been published in the current format since 1956. The Quarterly Summaries (1956 through 1973) and the Annual Summaries (1974 through 1985) were originally published as Administrative Reports. These reports have been compiled and published as U.S. Geological Survey Open-File Reports. The quarterly reports have been combined and published as one annual summary. All the summaries from 1956 to the present are now available as .pdf files at http://www.usgs.gov/pubprod. This report consists of four parts.

  20. Galactic Super-volcano in Action

    NASA Astrophysics Data System (ADS)

    2010-08-01

    A galactic "super-volcano" in the massive galaxy M87 is erupting and blasting gas outwards, as witnessed by NASA's Chandra X-ray Observatory and NSF's Very Large Array. The cosmic volcano is being driven by a giant black hole in the galaxy's center and preventing hundreds of millions of new stars from forming. Astronomers studying this black hole and its effects have been struck by the remarkable similarities between it and a volcano in Iceland that made headlines earlier this year. At a distance of about 50 million light years, M87 is relatively close to Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies. M87's location, coupled with long observations over Chandra's lifetime, has made it an excellent subject for investigations of how a massive black hole impacts its environment. "Our results show in great detail that supermassive black holes have a surprisingly good control over the evolution of the galaxies in which they live," said Norbert Werner of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the SLAC National Accelerator Laboratory, who led one of two papers describing the study. "And it doesn't stop there. The black hole's reach extends ever farther into the entire cluster, similar to how one small volcano can affect practically an entire hemisphere on Earth." The cluster surrounding M87 is filled with hot gas glowing in X-ray light, which is detected by Chandra. As this gas cools, it can fall toward the galaxy's center where it should continue to cool even faster and form new stars. However, radio observations with the Very Large Array suggest that in M87 jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the center of the galaxy and produce shock waves in the galaxy's atmosphere because of their supersonic speed. The scientists involved in this research have found the interaction of this cosmic

  1. Magmatic gas scrubbing: Implications for volcano monitoring

    USGS Publications Warehouse

    Symonds, R.B.; Gerlach, T.M.; Reed, M.H.

    2001-01-01

    Despite the abundance of SO2(g) in magmatic gases, precursory increases in magmatic SO2(g) are not always observed prior to volcanic eruption, probably because many terrestrial volcanoes contain abundant groundwater or surface water that scrubs magmatic gases until a dry pathway to the atmosphere is established. To better understand scrubbing and its implications for volcano monitoring, we model thermochemically the reaction of magmatic gases with water. First, we inject a 915??C magmatic gas from Merapi volcano into 25??C air-saturated water (ASW) over a wide range of gas/water mass ratios from 0.0002 to 100 and at a total pressure of 0.1 MPa. Then we model closed-system cooling of the magmatic gas, magmatic gas-ASW mixing at 5.0 MPa, runs with varied temperature and composition of the ASW, a case with a wide range of magmatic-gas compositions, and a reaction of a magmatic gas-ASW mixture with rock. The modeling predicts gas and water compositions, and, in one case, alteration assemblages for a wide range of scrubbing conditions; these results can be compared directly with samples from degassing volcanoes. The modeling suggests that CO2(g) is the main species to monitor when scrubbing exists; another candidate is H2S(g), but it can be affected by reactions with aqueous ferrous iron. In contrast, scrubbing by water will prevent significant SO2(g) and most HCl(g) emissions until dry pathways are established, except for moderate HCl(g) degassing from pH 100 t/d (tons per day) of SO2(g) in addition to CO2(g) and H2S(g) should be taken as a criterion of magma intrusion. Finally, the modeling suggests that the interpretation of gas-ratio data requires a case-by-case evaluation since ratio changes can often be produced by several mechanisms; nevertheless, several gas ratios may provide useful indices for monitoring the drying out of gas pathways. Published by Elsevier Science B.V.

  2. Geology of El Chichon volcano, Chiapas, Mexico

    NASA Astrophysics Data System (ADS)

    Duffield, Wendell A.; Tilling, Robert I.; Canul, Rene

    1984-03-01

    The (pre-1982) 850-m-high andesitic stratovolcano El Chichón, active during Pleistocene and Holocene time, is located in rugged, densely forested terrain in northcentral Chiapas, México. The nearest neighboring Holocene volcanoes are 275 km and 200 km to the southeast and northwest, respectively. El Chichón is built on Tertiary siltstone and sandstone, underlain by Cretaceous dolomitic limestone; a 4-km-deep bore hole near the east base of the volcano penetrated this limestone and continued 770 m into a sequence of Jurassic or Cretaceous evaporitic anhydrite and halite. The basement rocks are folded into generally northwest-trending anticlines and synclines. El Chichón is built over a small dome-like structure superposed on a syncline, and this structure may reflect cumulative deformation related to growth of a crustal magma reservoir beneath the volcano. The cone of El Chichón consists almost entirely of pyroclastic rocks. The pre-1982 cone is marked by a 1200-m-diameter (explosion?) crater on the southwest flank and a 1600-m-diameter crater apparently of similar origin at the summit, a lava dome partly fills each crater. The timing of cone and dome growth is poorly known. Field evidence indicates that the flank dome is older than the summit dome, and K-Ar ages from samples high on the cone suggest that the flank dome is older than about 276,000 years. At least three pyroclastic eruptions have occurred during the past 1250 radiocarbon years. Nearly all of the pyroclastic and dome rocks are moderately to highly porphyritic andesite, with plagioclase, hornblende and clinopyroxene the most common phenocrysts. Geologists who mapped El Chichón in 1980 and 1981 warned that the volcano posed a substantial hazard to the surrounding region. This warning was proven to be prophetic by violent eruptions that occurred in March and April of 1982. These eruptions blasted away nearly all of the summit dome, blanketed the surrounding region with tephra, and sent pyroclastic

  3. Geology of El Chichon volcano, Chiapas, Mexico

    USGS Publications Warehouse

    Duffield, W.A.; Tilling, R.I.; Canul, R.

    1984-01-01

    The (pre-1982) 850-m-high andesitic stratovolcano El Chicho??n, active during Pleistocene and Holocene time, is located in rugged, densely forested terrain in northcentral Chiapas, Me??xico. The nearest neighboring Holocene volcanoes are 275 km and 200 km to the southeast and northwest, respectively. El Chicho??n is built on Tertiary siltstone and sandstone, underlain by Cretaceous dolomitic limestone; a 4-km-deep bore hole near the east base of the volcano penetrated this limestone and continued 770 m into a sequence of Jurassic or Cretaceous evaporitic anhydrite and halite. The basement rocks are folded into generally northwest-trending anticlines and synclines. El Chicho??n is built over a small dome-like structure superposed on a syncline, and this structure may reflect cumulative deformation related to growth of a crustal magma reservoir beneath the volcano. The cone of El Chicho??n consists almost entirely of pyroclastic rocks. The pre-1982 cone is marked by a 1200-m-diameter (explosion?) crater on the southwest flank and a 1600-m-diameter crater apparently of similar origin at the summit, a lava dome partly fills each crater. The timing of cone and dome growth is poorly known. Field evidence indicates that the flank dome is older than the summit dome, and K-Ar ages from samples high on the cone suggest that the flank dome is older than about 276,000 years. At least three pyroclastic eruptions have occurred during the past 1250 radiocarbon years. Nearly all of the pyroclastic and dome rocks are moderately to highly porphyritic andesite, with plagioclase, hornblende and clinopyroxene the most common phenocrysts. Geologists who mapped El Chicho??n in 1980 and 1981 warned that the volcano posed a substantial hazard to the surrounding region. This warning was proven to be prophetic by violent eruptions that occurred in March and April of 1982. These eruptions blasted away nearly all of the summit dome, blanketed the surrounding region with tephra, and sent

  4. Monogenetic volcanoes of the terrestrial planets

    NASA Technical Reports Server (NTRS)

    Wood, C. A.

    1979-01-01

    Monogenetic volcanic activity has produced cinder cones and small shield volcanoes on the earth, moon, and Mars. Extraterrestrial cinder cones have median volumes only 25% as large as average terrestrial cinder cones, implying that their magma chambers are smaller and shallower (1 km depth vs 3 km). Ejection velocities for lunar and Martian cinder cones range from 20 to 70 m/sec, only 1/3 to 1/10 as high as for equal volume terrestrial eruptions. These low velocities imply low volatile contents for both Martian and lunar magmas.

  5. Mount St. Helens Volcano, WA, USA

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Mount St. Helens Volcano (46.0N, 122.0W) and its blast zone can be seen in this northeast looking infrared view. Mt. Rainier and Mt. Adams can also be seen in the near area. The Columbia River can be seen at the bottom of the view. When Mt. St. Helens erupted on 18 May 80, the top 1300 ft. disappeared within minutes. The blast area covered an area of more than 150 sq. miles and sent thousands of tons of ash into the upper atmosphere.

  6. Publications of the Volcano Hazards Program 2009

    USGS Publications Warehouse

    Nathenson, Manuel

    2011-01-01

    The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity as funded by congressional appropriation. Investigations are carried out in the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Hawaii Manoa and Hilo, University of Utah, and University of Washington Geophysics Program. This report lists publications from all these institutions. Only published papers and maps are included here; numerous abstracts presented at scientific meetings are omitted. Publications dates are based on year of issue, with no attempt to assign them to fiscal year.

  7. Publications of the Volcano Hazards Program 2011

    USGS Publications Warehouse

    Nathenson, Manuel

    2013-01-01

    The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity, as funded by Congressional appropriation. Investigations are carried out by the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Hawaii Manoa and Hilo, University of Utah, and University of Washington Geophysics Program. This report lists publications from all these institutions. Only published papers and maps are included here; abstracts presented at scientific meetings are omitted. Publication dates are based on year of issue, with no attempt to assign them to fiscal year.

  8. Publications of the Volcano Hazards Program 2012

    USGS Publications Warehouse

    Nathenson, Manuel

    2014-01-01

    The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity, as funded by Congressional appropriation. Investigations are carried out by the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Hawaii Manoa and Hilo, University of Utah, and University of Washington Geophysics Program. This report lists publications from all of these institutions. Only published papers and maps are included here; abstracts presented at scientific meetings are omitted. Publication dates are based on year of issue, with no attempt to assign them to a fiscal year.

  9. Publications of the Volcano Hazards Program 2010

    USGS Publications Warehouse

    Nathenson, Manuel

    2012-01-01

    The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity as funded by Congressional appropriation. Investigations are carried out in the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Hawaii Manoa and Hilo, University of Utah, and University of Washington Geophysics Program. This report lists publications from all these institutions. Only published papers and maps are included here; numerous abstracts presented at scientific meetings are omitted. Publication dates are based on year of issue, with no attempt to assign them to fiscal year.

  10. Publications of Volcano Hazards Program 2000

    USGS Publications Warehouse

    Nathenson, Manuel

    2001-01-01

    The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity as funded by Congressional appropriation. Investigations are carried out in the Geology and Hydrology Disciplines of the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Utah, and University of Washington Geophysics Program. This report lists publications from all these institutions. This report contains only published papers and maps; numerous abstracts produced for presentations at scientific meetings have not been included. Publications are included based on date of publication with no attempt to assign them to Fiscal Year.

  11. Lava Flows On Ascraeus Mons Volcano

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Ascraeus Mons Volcano: Like Earth, Mars has many volcanoes and volcanic features. This high-resolution view shows some of the lava flows near the summit of Ascraeus Mons, one of the three giant shield volcanoes known as the 'Tharsis Montes'. Volcanoes form when magma (molten rock) erupts out onto the surface of a planet. Based on Viking-era observations, Ascraeus Mons is considered to be one of the tallest volcanoes on Mars... its summit is more than 11 km (6.8 miles) above the surrounding plain. The summit is more than 23 km (14 miles) higher in elevation than the place where Mars Pathfinder landed in July 1997.

    Description of MOC Image: This picture shows an area that is about 20 km (12 miles) higher in elevation than the Mars Pathfinder landing site. The picture shows three main features: (1) a crater at the center-right, (2) a sinuous, discontinuous channel across the upper half, and (3) a rough and pitted, elevated surface across the lower half of the image.

    (1) Crater at center right. Distinguishing meteor craters from volcanic craters can sometimes be a challenge on Mars. This particular crater was most likely formed by meteor impact because it has a raised rim and a faint radial ejecta pattern around the outside of it. This crater is 600 m (2000 feet) across, about 3/4 the size of the famous 'Meteor Crater' near Winslow, Arizona.

    (2) Sinuous channel. The type of discontinuous channel running across the upper half of the image is sometimes referred to as a 'sinuous rille'. These are common on the volcanic plains of the Moon and among volcanoes and volcanic plains on Earth. Such a channel was once a lava tube. It is running down the middle of an old lava flow. The 'tube' looks like a 'channel' because its roof has collapsed. The discontinuous nature of this channel is the result of the collapse, or 'cave-in' of what was once the roof of the lava tube. It is common for certain types of relatively fluid lavas to form

  12. Geology of Medicine Lake Volcano, Northern California Cascade Range

    USGS Publications Warehouse

    Donnelly-Nolan, Julie

    1990-01-01

    Medicine Lake volcano (MLV) is located in an E-W extensional environment on the Modoc Plateau just east of the main arc of the Cascades. It consists mainly of mafic lavas, although drillhole data indicate that a larger volume of rhyolite is present than is indicated by surface mapping. The most recent eruption was rhyolitic and occurred about 900 years ago. At least seventeen eruptions have occurred since 12,000 years ago, or between 1 and 2 eruptions per century on average, although activity appears to be strongly episodic. The calculated eruptive rate is about 0.6 km3 per thousand years during the entire history of the volcano. Drillhole data indicate that the plateau surface underlying the volcano has been downwarped by 0.5 km under the center of MLV. The volcano may be even larger than the estimated 600 km3, already the largest volcano by volume in the Cascades.

  13. Establishment, test and evaluation of a prototype volcano surveillance system

    NASA Technical Reports Server (NTRS)

    Ward, P. L.; Eaton, J. P.; Endo, E.; Harlow, D.; Marquez, D.; Allen, R.

    1973-01-01

    A volcano-surveillance system utilizing 23 multilevel earthquake counters and 6 biaxial borehole tiltmeters is being installed and tested on 15 volcanoes in 4 States and 4 foreign countries. The purpose of this system is to give early warning when apparently dormant volcanoes are becoming active. The data are relayed through the ERTS-Data Collection System to Menlo Park for analysis. Installation was completed in 1972 on the volcanoes St. Augustine and Iliamna in Alaska, Kilauea in Hawaii, Baker, Rainier and St. Helens in Washington, Lassen in California, and at a site near Reykjavik, Iceland. Installation continues and should be completed in April 1973 on the volcanoes Santiaguito, Fuego, Agua and Pacaya in Guatemala, Izalco in El Salvador and San Cristobal, Telica and Cerro Negro in Nicaragua.

  14. Tsunamis generated by eruptions from mount st. Augustine volcano, alaska.

    PubMed

    Kienle, J; Kowalik, Z; Murty, T S

    1987-06-12

    During an eruption of the Alaskan volcano Mount St. Augustine in the spring of 1986, there was concern about the possibility that a tsunami might be generated by the collapse of a portion of the volcano into the shallow water of Cook Inlet. A similar edifice collapse of the volcano and ensuing sea wave occurred during an eruption in 1883. Other sea waves resulting in great loss of life and property have been generated by the eruption of coastal volcanos around the world. Although Mount St. Augustine remained intact during this eruptive cycle, a possible recurrence of the 1883 events spurred a numerical simulation of the 1883 sea wave. This simulation, which yielded a forecast of potential wave heights and travel times, was based on a method that could be applied generally to other coastal volcanos. PMID:17793232

  15. Translating Volcano Hazards Research in the Cascades Into Community Preparedness

    NASA Astrophysics Data System (ADS)

    Ewert, J. W.; Driedger, C. L.

    2015-12-01

    Research by the science community into volcanic histories and physical processes at Cascade volcanoes in the states of Washington, Oregon, and California has been ongoing for over a century. Eruptions in the 20th century at Lassen Peak and Mount St. Helen demonstrated the active nature of Cascade volcanoes; the 1980 eruption of Mount St. Helens was a defining moment in modern volcanology. The first modern volcano hazards assessments were produced by the USGS for some Cascade volcanoes in the 1960s. A rich scientific literature exists, much of which addresses hazards at these active volcanoes. That said community awareness, planning, and preparation for eruptions generally do not occur as a result of a hazard analyses published in scientific papers, but by direct communication with scientists. Relative to other natural hazards, volcanic eruptions (or large earthquakes, or tsunami) are outside common experience, and the public and many public officials are often surprised to learn of the impacts volcanic eruptions could have on their communities. In the 1980s, the USGS recognized that effective hazard communication and preparedness is a multi-faceted, long-term undertaking and began working with federal, state, and local stakeholders to build awareness and foster community action about volcano hazards. Activities included forming volcano-specific workgroups to develop coordination plans for volcano emergencies; a concerted public outreach campaign; curriculum development and teacher training; technical training for emergency managers and first responders; and development of hazard information that is accessible to non-specialists. Outcomes include broader ownership of volcano hazards as evidenced by bi-national exchanges of emergency managers, community planners, and first responders; development by stakeholders of websites focused on volcano hazards mitigation; and execution of table-top and functional exercises, including evacuation drills by local communities.

  16. Birth of a lava lake: Nyamulagira volcano 2011-2015

    NASA Astrophysics Data System (ADS)

    Coppola, D.; Campion, R.; Laiolo, M.; Cuoco, E.; Balagizi, C.; Ripepe, M.; Cigolini, C.; Tedesco, D.

    2016-03-01

    Since 1938, Nyamulagira volcano (Democratic Republic of Congo) has operated as a classic pressurized basaltic closed system, characterized by frequent dike-fed flank eruptions. However, on June 24, 2014, an active lava lake was observed in its summit, after a period of 76 years. The small lava lake is now exposed at the bottom of a pit-crater and is rising and growing. Based on satellite-derived infrared (IR) data, SO2 fluxes and periodic field surveys, we provide evidence that the development of the lava lake was gradual and occurred more than 2 years before it was first observed in the field. Notably, this process followed the voluminous 2011-2012 distal flank eruption and was coeval with weakening of the central rock column below the summit. Hence, the opening and development of the pit-crater favoured the continuous rise of fresh magma through the central conduit and promoted the gradual "re-birth" of the Nyamulagira lava lake. Budgeted volumes of magma erupted, and magma degassed at depth indicate that the formation of the lava lake is due to the draining and refilling of a shallow plumbing system (1-2 km depth), probably in response to the rift-parallel 2011-2012 distal eruption. We thus suggest that the transition from lateral to central activity did not result from a substantial change in the magma supply rate but, more likely, from the perturbation of the plumbing system (and related stress field) associated with the distal eruption. The processes observed at Nyamulagira are not unique and suggest that rift-fissure eruptions, in addition to triggering caldera collapses or lava lake drainages, may also induce a progressive resumption of central vent activity. Current activity at Nyamulagira represents a tangible and major hazard for the population living at the base of its southern flank.

  17. Snapshot of Southern Spring Dust Storm Activity

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Southern spring on Mars began with a 'bang' in late June 2001 with a series of large dust storms that in some regions were still occurring each day well into September. By early July, the martian atmosphere was so hazy that opportunities for high resolution imaging of the planet were very limited. This wide angle camera view obtained by the Mars Global Surveyor Mars Orbiter Camera shows a large dust-raising event that occurred on July 8, 2001, as cold, raging winds blew off the frozen south polar cap (bottom) and rushed toward the network of troughs known as Labyrinthus Noctis near the martian equator (center). A second, smaller dust storm can be seen near the top just left of center, northwest of the Ascraeus Mons volcano (uppermost dark elliptical feature). To give a sense of scale, Ascraeus Mons is large enough to nearly cover the state of Washington, home of the famous (and much smaller) Mount St. Helens volcano. Sunlight illuminates the scene from the left, and north is toward the upper right.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  18. Are Monogenetic Basaltic Explosive Volcanoes Good Analogues for Explosive Kimberlite Volcanoes?

    NASA Astrophysics Data System (ADS)

    Cas, R. A.

    2009-05-01

    There is uncertainty as to the nature of kimberlite volcanoes because the edifices of ancient kimberlite volcanoes have been largely eroded. Monogenetic basaltic explosive volcanoes, such as scoria or cinder cones and maars, are often proposed as good analogues for kimberlite volcanoes. Basaltic scoria or cinder cones form from explosive eruptions driven by exsolving magmatic gases. The sparsity of country rock xenoliths in the deposits of scoria cones indicates the explosive fragmentation surface lay at or above the pre- eruption ground surface in the vent and conduit system, and therefore a sub-surface diatreme or pipe-like conduit cannot be formed. Basaltic scoria cones are therefore not good analogues for most kimberlite pipes and volcanoes. By contrast, the volcaniclastic kimberlite pipe fill of most kimberlite pipes contains a significant proportion of country rock xenolith and xenocryst debris (10 to 50 modal percent or more), indicating that the fragmentation surface lay below the ground surface, and this was responsible for explosively excavating the subsurface diatreme or pipe like conduit. Some authors propose that this is consistent with kimberlite pipes being the remains of maar volcanoes. The deposits of maar volcanoes usually contain substantial country rock debris suggesting excavation of a significant subsurface conduit has occurred. Maar forming explosive eruptions are phreatomagmatic, driven in large part by explosive superheating of ground water as magma passes upwards through a shallow crustal aquifer. The deposits however commonly show two key characteristics, base surge deposits and accretionary lapilli. Although these occur in some kimberlite deposits, attesting to the occurrence of phreatomagmatic explosive activity in those kimberlite volcanoes, in the absence of such features occurring universally in kimberlite pipes, it is difficult to support a maar volcanic model for kimberlite pipes. If the volatile content in a rising magma is high

  19. GlobVolcano pre-operational services for global monitoring active volcanoes

    NASA Astrophysics Data System (ADS)

    Tampellini, Lucia; Ratti, Raffaella; Borgström, Sven; Seifert, Frank Martin; Peltier, Aline; Kaminski, Edouard; Bianchi, Marco; Branson, Wendy; Ferrucci, Fabrizio; Hirn, Barbara; van der Voet, Paul; van Geffen, J.

    2010-05-01

    The GlobVolcano project (2007-2010) is part of the Data User Element programme of the European Space Agency (ESA). The project aims at demonstrating Earth Observation (EO) based integrated services to support the Volcano Observatories and other mandate users (e.g. Civil Protection) in their monitoring activities. The information services are assessed in close cooperation with the user organizations for different types of volcano, from various geographical areas in various climatic zones. In a first phase, a complete information system has been designed, implemented and validated, involving a limited number of test areas and respective user organizations. In the currently on-going second phase, GlobVolcano is delivering pre-operational services over 15 volcanic sites located in three continents and as many user organizations are involved and cooperating with the project team. The set of GlobVolcano offered EO based information products is composed as follows: Deformation Mapping DInSAR (Differential Synthetic Aperture Radar Interferometry) has been used to study a wide range of surface displacements related to different phenomena (e.g. seismic faults, volcanoes, landslides) at a spatial resolution of less than 100 m and cm-level precision. Permanent Scatterers SAR Interferometry method (PSInSARTM) has been introduced by Politecnico of Milano as an advanced InSAR technique capable of measuring millimetre scale displacements of individual radar targets on the ground by using multi-temporal data-sets, estimating and removing the atmospheric components. Other techniques (e.g. CTM) have followed similar strategies and have shown promising results in different scenarios. Different processing approaches have been adopted, according to data availability, characteristic of the area and dynamic characteristics of the volcano. Conventional DInSAR: Colima (Mexico), Nyiragongo (Congo), Pico (Azores), Areanal (Costa Rica) PSInSARTM: Piton de la Fournaise (La Reunion Island

  20. Abrupt transition from fractional crystallization to magma mixing at Gorely volcano (Kamchatka) after caldera collapse

    NASA Astrophysics Data System (ADS)

    Gavrilenko, Maxim; Ozerov, Alexey; Kyle, Philip R.; Carr, Michael J.; Nikulin, Alex; Vidito, Christopher; Danyushevsky, Leonid

    2016-07-01

    A series of large caldera-forming eruptions (361-38 ka) transformed Gorely volcano, southern Kamchatka Peninsula, from a shield-type system dominated by fractional crystallization processes to a composite volcanic center, exhibiting geochemical evidence of magma mixing. Old Gorely, an early shield volcano (700-361 ka), was followed by Young Gorely eruptions. Calc-alkaline high magnesium basalt to rhyolite lavas have been erupted from Gorely volcano since the Pleistocene. Fractional crystallization dominated evolution of the Old Gorely magmas, whereas magma mixing is more prominent in the Young Gorely eruptive products. The role of recharge-evacuation processes in Gorely magma evolution is negligible (a closed magmatic system); however, crustal rock assimilation plays a significant role for the evolved magmas. Most Gorely magmas differentiate in a shallow magmatic system at pressures up to 300 MPa, ˜3 wt% H2O, and oxygen fugacity of ˜QFM + 1.5 log units. Magma temperatures of 1123-1218 °C were measured using aluminum distribution between olivine and spinel in Old and Young Gorely basalts. The crystallization sequence of major minerals for Old Gorely was as follows: olivine and spinel (Ol + Sp) for mafic compositions (more than 5 wt% of MgO); clinopyroxene and plagioclase crystallized at ˜5 wt% of MgO (Ol + Cpx + Plag) and magnetite at ˜3.5 wt% of MgO (Ol + Cpx + Plag + Mt). We show that the shallow magma chamber evolution of Old Gorely occurs under conditions of decompression and degassing. We find that the caldera-forming eruption(s) modified the magma plumbing geometry. This led to a change in the dominant magma evolution process from fractional crystallization to magma mixing. We further suggest that disruption of the magma chamber and accompanying change in differentiation process have the potential to transform a shield volcanic system to that of composite cone on a global scale.

  1. Looking for Larvae Above an Erupting Submarine Volcano, NW Rota-1, Mariana Arc

    NASA Astrophysics Data System (ADS)

    Hanson, M.; Beaulieu, S.; Tunnicliffe, V.; Chadwick, W.; Breuer, E. R.

    2015-12-01

    In 2009 the first marine protected areas for deep-sea hydrothermal vents in U.S. waters were established as part of the Volcanic Unit of the Marianas Trench Marine National Monument. In this region, hydrothermal vents are located along the Mariana Arc and back-arc spreading center. In particular hydrothermal vents are located near the summit of NW Rota-1, an active submarine volcano on the Mariana Arc which was erupting between 2003 through 2010 and ceased as of 2014. In late 2009, NW Rota-1 experienced a massive landslide decimating the habitat on the southern side of the volcano. This presented an enormous natural disturbance to the community. This project looked at zooplankton tow samples taken from the water column above NW Rota-1 in 2010, searching specifically for larvae which have the potential to recolonize the sea floor after such a major disturbance. We focused on samples for which profiles with a MAPR sensor indicated hydrothermal plumes in the water column. Samples were sorted in entirety into coarse taxa, and then larvae were removed for DNA barcoding. Overall zooplankton composition was dominated by copepods, ostracods, and chaetognaths, the majority of which are pelagic organisms. Comparatively few larvae of benthic invertebrates were found, but shrimp, gastropod, barnacle, and polychaete larvae did appear in low numbers in the samples. Species-level identification obtained via genetic barcoding will allow for these larvae to be matched to species known to inhabit the benthic communities at NW Rota-1. Identified larvae will give insight into the organisms which can re-colonize the seafloor vent communities after a disturbance such as the 2009 landslide. Communities at hydrothermal vents at other submarine volcanoes in the Monument also can act as sources for these planktonic, recolonizing larvae. As the microinvertebrate biodiversity in the Monument has yet to be fully characterized, our project also provides an opportunity to better describe both

  2. Active Source Tomography of Stromboli Volcano (Italy): Results From the 2006 Seismic Experiment.

    NASA Astrophysics Data System (ADS)

    Zuccarello, L.; Patanè, D.; Cocina, O.; Castellano, M.; Sgroi, T.; Favali, P.; de Gori, P.

    2008-12-01

    Stromboli island, located in the Southern Tyrrhenian sea, is the emerged part (about 900 m a.s.l.) of a 3km-high strato-volcano. Its persistent Strombolian activity, documented for over 2000 years, is sometimes interrupted by lava effusions or major explosions. Despite the amount of recent published geophysical studies aimed to clarifying eruption dynamics, the spatial extend and geometrical characteristics of the plumbing system remain poorly understood. In fact, the knowledge of the inner structure and the zones of magma storage is limited to the upper few hundreds meters of the volcanic edifice and P- and S-waves velocity models are available only in restricted areas. In order to obtain a more suitable internal structural and velocity models of the volcano, from 25 November to 2 December 2006, a seismic tomography experiment through active seismics using air-gun sources was carried out and the final Vp model is here presented. The data has been inverted for the Vp structure by using the code Simulps13q, considering a 3D grid of nodes spaced 0.5 km down to 2 km depth, beneath the central part of volcano. The results show a relatively high velocity zones located both in the inner part of the volcanic structure, at about 1km b.s.l. and in the last 200-300 m a.s.l. in correspondence with the volcanic conduit. Slower zones were located around the summit craters in agreement with volcanological and petrological informations for the area. The relatively high velocity zones could suggest the presence of intrusive bodies related to the plumbing system.

  3. Long- and short-term triggering and modulation of mud volcano eruptions by earthquakes

    NASA Astrophysics Data System (ADS)

    Bonini, Marco; Rudolph, Maxwell L.; Manga, Michael

    2016-03-01

    Earthquakes can trigger the eruption of mud. We use eruptions in Azerbaijan, Italy, Romania, Japan, Andaman Islands, Pakistan, Taiwan, Indonesia, and California to probe the nature of stress changes that induce new eruptions and modulate ongoing eruptions. Dynamic stresses produced by earthquakes are usually inferred to be the dominant triggering mechanism; however static stress changes acting on the feeder systems of mud volcanoes may also play a role. In Azerbaijan, eruptions within 2-10 fault lengths from the epicenter are favored in the year following earthquakes where the static stress changes cause compression of the mud source and unclamp feeder dikes. In Romania, Taiwan, and some Italian sites, increased activity is also favored where the static stress changes act to unclamp feeder dikes, but responses occur within days. The eruption in the Andaman Islands, and those of the Niikappu mud volcanoes, Japan are better correlated with amplitude of dynamic stresses produced by seismic waves. Similarly, a new island that emerged off the coast of Pakistan in 2013 was likely triggered by dynamic stresses, enhanced by directivity. At the southern end of the Salton Sea, California earthquakes increase the gas flux at small mud volcanoes. Responses are best correlated with dynamic stresses. The comparison of responses in these nine settings indicates that dynamic stresses are most often correlated with triggering, although permanent stress changes as small as, and possibly smaller than, 0.1 bar may be sufficient to also influence eruptions. Unclamping stresses with magnitude similar to Earth tides (0.01 bar) persist over time and may play a role in triggering delayed responses. Unclamping stresses may be important contributors to short-term triggering only if they exceed 0.1-1 bar.

  4. The Ninole Basalt - Implications for the structural evolution of Mauna Loa volcano, Hawaii

    USGS Publications Warehouse

    Lipman, P.W.; Rhodes, J.M.; Dalrymple, G.B.

    1990-01-01

    Lava flows of the Ninole Basalt, the oldest rocks exposed on the south side of the island of Hawaii, provide age and compositional constraints on the evolution of Mauna Loa volcano and the southeastward age progression of Hawaiian volcanism. Although the tholeiitic Ninole Basalt differs from historic lavas of Mauna Loa volcano in most major-element contents (e.g., variably lower K, Na, Si; higher Al, Fe, Ti, Ca), REE and other relatively immobile minor elements are similar to historic and prehistoric Mauna Loa lavas, and the present major-element differences are mainly due to incipient weathering in the tropical environment. New K-Ar whole-rock ages, from relatively fresh roadcut samples, suggest that the age of the Ninole Basalt is approximately 0.1-0.2 Ma, although resolution is poor because of low contents of K and radiogenic Ar. Originally considered the remnants of a separate volcano, the Ninole Hills are here interpreted as faulted remnants of the old south flank of Mauna Loa. Deep canyons in the Ninole Hills, eroded after massive landslide failure of flanks of the southwest rift zone, have been preserved from burial by younger lava due to westward migration of the rift zone. Landslide-induced depressurization of the southwest rift zone may also have induced phreatomagmatic eruptions that could have deposited widespread Basaltic ash that overlies the Ninole Basalt. Subaerial presence of the Ninole Basalt documents that the southern part of Hawaii Island had grown to much of its present size above sea level by 0.1-0.2 Ma, and places significant limits on subsequent enlargement of the south flank of Mauna Loa. ?? 1990 Springer-Verlag.

  5. Habitat heterogeneity - biological association relationships in the asphalt volcano, SW Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Escobar, E.; Gaytan, A.

    2007-05-01

    A new class of cold seep, named asphalt volcano, was discovered in the Campeche Knolls region of the southern Gulf of Mexico, supporting chemosynthetic communities alike those lying at similar depth on the Angolan margin and the Barbados Prism suggesting an interesting longitudinal connectivity in the faunal components. The discovery of this novel deep-sea habitat has raised questions about diversity and process dynamics in this novel poorly described milieu. Results from two previous cruises jointly sponsored by German, US and Mexican funding agencies have allowed us to recognize the presence of large densities of background benthic megafauna, mainly represented by sea-cucumbers and galatheid crabs, which occupy diverse habitats in asphalt volcano and feed on microbial assemblages on the asphalt covering extended area. Asphalt displays different degrees of hardness suggesting ongoing activity of asphalt extrusion in the site that is reflected in biological benthic communities in different states succession and complexity. The fresh asphalt and the immediately surrounding soft sediment are colonized by mats of complex microbial assemblages where both background benthic megafauna and chemosynthetic tube worms and mussels aggregate. Our results focus on the diversity of the habitats associated with methane seepage through the example of geological structures in the asphalt volcano considering the small scale with the analysis of the relationships between biological assemblages and habitat heterogeneity assessing the role of the geological structure on biological communities. Bubbling of gas, oil and the content of thermogenic gas and gas hydrate in the asphalt suggests that the asphalt plays an important role as a reservoir of methane in this marginal deep sea.

  6. Hydrogen emissions from Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Moussallam, Yves; Oppenheimer, Clive; Aiuppa, Alessandro; Giudice, Gaetano; Moussallam, Manuel; Kyle, Philip

    2012-11-01

    The continuous measurement of molecular hydrogen (H2) emissions from passively degassing volcanoes has recently been made possible using a new generation of low-cost electrochemical sensors. We have used such sensors to measure H2, along with SO2, H2O and CO2, in the gas and aerosol plume emitted from the phonolite lava lake at Erebus volcano, Antarctica. The measurements were made at the crater rim between December 2010 and January 2011. Combined with measurements of the long-term SO2 emission rate for Erebus, they indicate a characteristic H2 flux of 0.03 kg s-1 (2.8 Mg day-1). The observed H2 content in the plume is consistent with previous estimates of redox conditions in the lava lake inferred from mineral compositions and the observed CO2/CO ratio in the gas plume (˜0.9 log units below the quartz-fayalite-magnetite buffer). These measurements suggest that H2 does not combust at the surface of the lake, and that H2 is kinetically inert in the gas/aerosol plume, retaining the signature of the high-temperature chemical equilibrium reached in the lava lake. We also observe a cyclical variation in the H2/SO2 ratio with a period of ˜10 min. These cycles correspond to oscillatory patterns of surface motion of the lava lake that have been interpreted as signs of a pulsatory magma supply at the top of the magmatic conduit.

  7. Comparing Volcano Infrasound and Aeroacoustics Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Ogden, D. E.; Matoza, R. S.; Fee, D.

    2012-12-01

    The production of acoustic noise by fluid flows has been studied experimentally within engineering aeroacoustics for over 50 years. These works aim to correlate flow properties and dynamics with the produced acoustic spectra (i.e., patterns of frequencies and amplitude). These correlations are used to design flow fields in man-made jet engines and other machines to reduce the production of harmful acoustic signals and resulting hearing loss. Many of the flow fields in these man-made systems are analogous to those in volcanic eruptions. We postulate that the acoustic signals generated by these flows are also analogous and the aeroacoustics experimental results provide a starting point for modeling the noise generated by volcanic flow fields. Application of empirical results from these experiments to volcanic flow fields is non-trivial. Volcanic eruptions involve complexities not present in man-made experiments including but not limited to multiphase flow, buoyancy forces, and non-uniform atmosphere. This work explores methods by which some of the empirical results from aeroacoustics experiments can be modified for application to volcanic eruptions. Results are compared with observations of volcano infrasound. Preliminary comparison to numerical simulations of volcano infrasound may also be presented.

  8. Volcano-ice interactions on Mars

    NASA Technical Reports Server (NTRS)

    Allen, C. C.

    1979-01-01

    Central volcanic eruptions beneath terrestrial glaciers have built steep-sided, flat-topped mountains composed of pillow lava, glassy tuff, capping flows, and cones of basalt. Subglacial fissure eruptions produced ridges of similar composition. In some places the products from a number of subglacial vents have combined to form widespread deposits. The morphologies of these subglacial volcanoes are distinctive enough to allow their recognition at the resolutions characteristic of Viking orbiter imagery. Analogs to terrestrial subglacial volcanoes have been identified on the northern plains and near the south polar cap of Mars. The polar feature provides probable evidence of volcanic eruptions beneath polar ice. A mixed unit of rock and ice is postulated to have overlain portions of the northern plains, with eruptions into this ground ice having produced mountains and ridges analogous to those in Iceland. Subsequent breakdown of this unit due to ice melting revealed the volcanic features. Estimated heights of these landforms indicate that the ice-rich unit once ranged from approximately 100 to 1200 m thick.

  9. Interior trough deposits on Mars: Subice volcanoes?

    USGS Publications Warehouse

    Chapman, M.G.; Tanaka, K.L.

    2001-01-01

    Widespread, several-kilometer-thick successions of layered deposits occur as mounds that partly fill the troughs or chasmata that compose the Valles Marineris on Mars. Like terrestrial subice volcanoes, the layered deposits occur in a volcano-tectonic setting within basins that may have held ponded water or ice. On the basis of their dimensions, morphologies, and associated catastrophic floods and other geologic events as shown in Viking and new Mars Global Surveyor (MGS) data sets, we suggest that the interior deposits are volcanic in origin and possibly generated by subice eruptions. A tuya origin for the mounds can explain the lack of external sediment, mound heights that can rival the plateau, local flat-topped mesas, morphologically distinct mounds of different ages, horizontal to steep dips, fine-grained materials, indications of rare volcanic vents and lava flows, and spectral composition. The extremely diverse layering of west Candor Chasma and possible volcanic cones in Melas may have formed by related subaerial eruptions. Consistent with the suggestion that interior deposits are eroding out of the wall rock, some deposits could have been erupted from sites along the walls.

  10. Monitoring Santorini volcano (Greece) breathing from space

    NASA Astrophysics Data System (ADS)

    Foumelis, Michael; Trasatti, Elisa; Papageorgiou, Elena; Stramondo, Salvatore; Parcharidis, Issaak

    2013-04-01

    Since its last eruption in 1950, Santorini volcano (Greece) remained in a dormant state. This is also evidenced for the period 1992-2010 by the gradual deflation signal over Nea Kameni as measured by satellite Synthetic Aperture Radar Interferometry (InSAR) with low rates of about 5-6 mm yr-1 as well as by the absence of seismic activity within the caldera. However, at the beginning of 2011 the volcano showed signs of unrest with increased microseismic activity and significant ground uplift, reaching 14 cm within a year (2011 March-2012 March), according to InSAR time-series. ALOS PALSAR data indicate the onset of the phenomenon in early 2010 where an aseismic pre-unrest phase of increased subsidence (1-3 cm) preceded the uplift. Joint inversions of SAR and GPS velocities using spherical and spheroidal magmatic source types indicate their location offshore at about 1 km north of Nea Kameni and between 3.5 and 3.8 km depth. The estimated volume variation rate is 6 × 106 m3 yr-1 to 9 × 106 m3 yr-1. A gradual slowing in the rate of inflation within the first quarter of 2012 is apparent by ENVISAT data, while subsequent observations from RADARSAT-2 confirm the observed trend.

  11. Stereo Image of Mt. Usu Volcano

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On April 3, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra Satellite captured this image of the erupting Mt. Usu volcano in Hokkaido, Japan. This anaglyph stereo image is of Mt Usu volcano. On Friday, March 31, more than 15,000 people were evacuated by helicopter, truck and boat from the foot of Usu, that began erupting from the northwest flank, shooting debris and plumes of smoke streaked with blue lightning thousands of feet in the air. Although no lava gushed from the mountain, rocks and ash continued to fall after the eruption. The region was shaken by thousands of tremors before the eruption. People said they could taste grit from the ash that was spewed as high as 2,700 meters (8,850 ft) into the sky and fell to coat surrounding towns with ash. A 3-D view can be obtained by looking through stereo glasses, with the blue film through your left eye and red film with your right eye at the same time. North is on your right hand side. For more information, see When Rivers of Rock Flow ASTER web page Image courtesy of MITI, ERSDAC, JAROS, and the U.S./Japan ASTER Science Team

  12. Hydrothermal system at Newberry Volcano, Oregon

    SciTech Connect

    Sammel, E.A.; I