WorldWideScience

Sample records for active submarine volcano

  1. Long-term eruptive activity at a submarine arc volcano.

    Science.gov (United States)

    Embley, Robert W; Chadwick, William W; Baker, Edward T; Butterfield, David A; Resing, Joseph A; de Ronde, Cornel E J; Tunnicliffe, Verena; Lupton, John E; Juniper, S Kim; Rubin, Kenneth H; Stern, Robert J; Lebon, Geoffrey T; Nakamura, Ko-ichi; Merle, Susan G; Hein, James R; Wiens, Douglas A; Tamura, Yoshihiko

    2006-05-25

    Three-quarters of the Earth's volcanic activity is submarine, located mostly along the mid-ocean ridges, with the remainder along intraoceanic arcs and hotspots at depths varying from greater than 4,000 m to near the sea surface. Most observations and sampling of submarine eruptions have been indirect, made from surface vessels or made after the fact. We describe here direct observations and sampling of an eruption at a submarine arc volcano named NW Rota-1, located 60 km northwest of the island of Rota (Commonwealth of the Northern Mariana Islands). We observed a pulsating plume permeated with droplets of molten sulphur disgorging volcanic ash and lapilli from a 15-m diameter pit in March 2004 and again in October 2005 near the summit of the volcano at a water depth of 555 m (depth in 2004). A turbid layer found on the flanks of the volcano (in 2004) at depths from 700 m to more than 1,400 m was probably formed by mass-wasting events related to the eruption. Long-term eruptive activity has produced an unusual chemical environment and a very unstable benthic habitat exploited by only a few mobile decapod species. Such conditions are perhaps distinctive of active arc and hotspot volcanoes.

  2. Researchers rapidly respond to submarine activity at Loihi Volcano, Hawaii

    Science.gov (United States)

    The 1996 Loihi Science Team

    The largest swarm of earthquakes ever observed at a Hawaiian volcano occurred at Loihi Seamount during July and early August 1996. The earthquake activity formed a large summit pit crater similar to those observed at Kilauea, and hydrothermal activity led to the formation of intense hydrothermal plumes in the ocean surrounding the summit. To investigate this event, the Rapid Response Cruise (RRC) was dispatched to Loihi in early August and two previously planned LONO cruises (named for a Hawaiian warrior god) sailed in September and October on the R/V Kaimikai-O-Kanaloa. Calm weather and a newly refurbished ship provided excellent opportunities for documenting the volcanic, hydrothermal plume, vent, and biological activities associated with the earthquake swarm.

  3. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system.

    Science.gov (United States)

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-06-17

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report (3)He/(4)He measurements in CO2-dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a (3)He/(4)He signature of at least 7.0 Ra (being Ra the (3)He/(4)He ratio of atmospheric He equal to 1.39×10(-6)), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like (3)He/(4)He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano.

  4. Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands

    Science.gov (United States)

    Watson, S. J.; Coffin, M. F.; Whittaker, J. M.; Lucieer, V.; Fox, J. M.; Carey, R.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Martin, T.; Cooke, F.

    2016-12-01

    Heard and McDonald Islands (HIMI) are World Heritage listed sub-Antarctic active volcanic islands in the Southern Indian Ocean. Built atop the Kerguelen Plateau by Neogene-Quaternary volcanism, HIMI represent subaerial exposures of the second largest submarine Large Igneous Province globally. Onshore, processes influencing island evolution include glaciers, weathering, volcanism, vertical tectonics and mass-wasting (Duncan et al. 2016). Waters surrounding HIMI are largely uncharted, due to their remote location. Hence, the extent to which these same processes shape the submarine environment around HIMI has not been investigated. In early 2016, we conducted marine geophysical and geologic surveys around HIMI aboard RV Investigator (IN2016_V01). Results show that volcanic and sedimentary features prominently trend east-west, likely a result of erosion by the eastward flowing Antarctic Circumpolar Current and tidal currents. However, spatial patterns of submarine volcanism and sediment distribution differ substantially between the islands. >70 sea knolls surround McDonald Island suggesting substantial submarine volcanism. Geophysical data reveals hard volcanic seafloor around McDonald Island, whereas Heard Island is characterised by sedimentary sequences tens of meters or more thick and iceberg scours - indicative of glacial processes. Differences in submarine geomorphology are likely due to the active glaciation of Heard Island and differing rock types (Heard: alkali basalt, McDonald: phonolite), and dominant products (clastics vs. lava). Variations may also reflect different magmatic plumbing systems beneath the two active volcanoes (Heard produces larger volumes of more focused lava, whilst McDonald extrudes smaller volumes of more evolved lavas from multiple vents across the edifice). Using geophysical data, corroborated with new and existing geologic data, we present the first geomorphic map revealing the processes that shape the submarine environment around HIMI.

  5. Hydrodynamic modeling of magmatic-hydrothermal activity at submarine arc volcanoes, with implications for ore formation

    Science.gov (United States)

    Gruen, Gillian; Weis, Philipp; Driesner, Thomas; Heinrich, Christoph A.; de Ronde, Cornel E. J.

    2014-10-01

    Subduction-related magmas have higher volatile contents than mid-ocean ridge basalts, which affects the dynamics of associated submarine hydrothermal systems. Interaction of saline magmatic fluids with convecting seawater may enhance ore metal deposition near the seafloor, making active submarine arcs a preferred modern analogue for understanding ancient massive sulfide deposits. We have constructed a quantitative hydrological model for sub-seafloor fluid flow based on observations at Brothers volcano, southern Kermadec arc, New Zealand. Numerical simulations of multi-phase hydrosaline fluid flow were performed on a two-dimensional cross-section cutting through the NW Caldera and the Upper Cone sites, two regions of active venting at the Brothers volcanic edifice, with the former hosting sulfide mineralization. Our aim is to explore the flow paths of saline magmatic fluids released from a crystallizing magma body at depth and their interaction with seawater circulating through the crust. The model includes a 3 × 2km2 sized magma chamber emplaced at ∼ 2.5 km beneath the seafloor connected to the permeable cone via a ∼ 200 m wide feeder dike. During the simulation, a magmatic fluid was temporarily injected from the top of the cooling magma chamber into the overlying convection system, assuming hydrostatic conditions and a static permeability distribution. The simulations predict a succession of hydrologic regimes in the subsurface of Brothers volcano, which can explain some of the present-day hydrothermal observations. We find that sub-seafloor phase separation, inferred from observed vent fluid salinities, and the temperatures of venting at Brothers volcano can only be achieved by input of a saline magmatic fluid at depth, consistent with chemical and isotopic data. In general, our simulations show that the transport of heat, water, and salt from magmatic and seawater sources is partly decoupled. Expulsion of magmatic heat and volatiles occurs within the first

  6. Submarine explosive activity and ocean noise generation at Monowai Volcano, Kermadec Arc: constraints from hydroacoustic T-waves

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    Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony

    2016-04-01

    Submarine volcanic activity is difficult to detect, because eruptions at depth are strongly attenuated by seawater. With increasing depth the ambient water pressure increases and limits the expansion of gas and steam such that volcanic eruptions tend to be less violent and less explosive with depth. Furthermore, the thermal conductivity and heat capacity of water causes rapid cooling of ejected products and hence erupted magma cools much more quickly than during subaerial eruptions. Therefore, reports on submarine volcanism are restricted to those sites where erupted products - like the presence of pumice rafts, gas bubbling on the sea surface, and local seawater colour changes - reach the sea surface. However, eruptions cause sound waves that travel over far distances through the Sound-Fixing-And-Ranging (SOFAR) channel, so called T-waves. Seismic networks in French Polynesia recorded T-waves since the 1980's that originated at Monowai Volcano, Kermadec Arc, and were attributed to episodic growth and collapse events. Repeated swath-mapping campaigns conducted between 1998 and 2011 confirm that Monowai volcano is a highly dynamic volcano. In July of 2007 a network of ocean-bottom-seismometers (OBS) and hydrophones was deployed and recovered at the end of January 2008. The instruments were located just to the east of Monowai between latitude 25°45'S and 27°30'S. The 23 OBS were placed over the fore-arc and on the incoming subducting plate to obtain local seismicity associated with plate bending and coupling of the subduction megathrust. However, we recognized additional non-seismic sleuths in the recordings. Events were best seen in 1 Hz high-pass filtered hydrophone records and were identified as T-waves. The term T-wave is generally used for waves travelling through the SOFAR channel over large distances. In our case, however, they were also detected on station down to ~8000 m, suggesting that waves on the sea-bed station were direct waves caused by explosive

  7. Growth History of Kaena Volcano, the Isolated, Dominantly Submarine, Precursor Volcano to Oahu, Hawaii

    Science.gov (United States)

    Sinton, J. M.; Eason, D. E.

    2014-12-01

    The construction of O'ahu began with the recently recognized, ~3.5-4.9 Ma Ka'ena Volcano, as an isolated edifice in the Kaua'i Channel. Ka'ena remained submarine until, near the end of its lifetime as magma supply waned and the volcano transitioned to a late-shield stage of activity, it emerged to reach a maximum elevation of ~1000 m above sea level. We estimate that Ka'ena was emergent only for the last 15-25% of its lifespan, and that subaerial lavas make up < 5% of the total volume (20-27 x 103 km3). O'ahu's other volcanoes, Wai'anae (~3.9-2.85 Ma) and Ko'olau (~3.0-1.9 Ma), were built at least partly on the flanks of earlier edifices and both were active subaerial volcanoes for at least 1 Ma. The constructional history of Ka'ena contrasts with that of Wai'anae, Ko'olau, and many other Hawaiian volcanoes, which likely emerge within a few hundred kyr after inception, and with subaerial lavas comprising up to 35 volume % of the volcano. These relations suggest that volcano growth history and morphology are critically dependent on whether volcanic initiation and growth occur in the deep ocean floor (isolated), or on the flanks of pre-existing edifices. Two other volcanoes that likely formed in isolation are West Moloka'i and Kohala, both of which have long submarine rift zones, and neither attained great heights above sea level despite having substantial volume. The partitioning of volcanism between submarine and subaerial volcanism depends on the distance between volcanic centers, whether new volcanoes initiate on the flanks of earlier ones, and the time over which neighboring volcanoes are concurrently active. Ka'ena might represent an end-member in this spectrum, having initiated far from its next oldest neighbor and completed much of its evolution in isolation.

  8. The Kolumbo submarine volcano of Santorini island is a large pool of bacterial strains with antimicrobial activity.

    Science.gov (United States)

    Bourbouli, Maria; Katsifas, Efstathios A; Papathanassiou, Evangelos; Karagouni, Amalia D

    2015-05-01

    Microbes in hydrothermal vents with their unique secondary metabolism may represent an untapped potential source of new natural products. In this study, samples were collected from the hydrothermal field of Kolumbo submarine volcano in the Aegean Sea, in order to isolate bacteria with antimicrobial activity. Eight hundred and thirty-two aerobic heterotrophic bacteria were isolated and then differentiated through BOX-PCR analysis at the strain level into 230 genomic fingerprints, which were screened against 13 different type strains (pathogenic and nonpathogenic) of Gram-positive, Gram-negative bacteria and fungi. Forty-two out of 176 bioactive-producing genotypes (76 %) exhibited antimicrobial activity against at least four different type strains and were selected for 16S rDNA sequencing and screening for nonribosomal peptide (NRPS) and polyketide (PKS) synthases genes. The isolates were assigned to genus Bacillus and Proteobacteria, and 20 strains harbored either NRPS, PKS type I or both genes. This is the first report on the diversity of culturable mesophilic bacteria associated with antimicrobial activity from Kolumbo area; the extremely high proportion of antimicrobial-producing strains suggested that this unique environment may represent a potential reservoir of novel bioactive compounds.

  9. NeMO-Net: A System for Near Real-Time Remote Sensing of Hydrothermal and Biological Activity in the Caldera of an Active Submarine Volcano

    Science.gov (United States)

    Hammond, S. R.; Butterfield, D.; Embley, R. W.; Meinig, C.; Stalin, S.

    2001-12-01

    In July of 2000, a camera and three temperature sensors were placed on the seafloor near a hydrothermal vent located in the caldera of an active submarine volcano. The volcano's summit lies at a depth of about 1500 m and is located at 46° N, 130° W, approximately 250 nautical miles off the Oregon coast. The volcano is the site of a long-term interdisciplinary study focused in part on discovering relationships between submarine volcanic and hydrothermal activity and a microbial biosphere which exists beneath the sea floor within the volcano's summit caldera. NeMO-Net utilizes an acoustic modem to communicate with a surface mooring anchored nearby. The mooring, in turn, is linked from the ocean surface to the Pacific Marine Environmental Laboratory by means of satellite systems. A unique feature of NeMO-Net is that it enables shore-based investigators to interrogate and command the system to perform specific tasks, the results of which are then reported back typically within several minutes . In the initial year-long deployment, photographic images, along with hourly readings from the three temperature probes, were available on a website which was updated every 24 hours. During the year, the camera documented a dynamic vent biological community as well as water temperature variations due to the influence of tides, and possibly with changing vent fluid temperatures The NeMO-Net system is under continuing development with particular emphasis on linking it to multiple sea floor instruments including near-real-time chemical and water samplers. Near-future plans also call for NeMO Net to be linked to a resident sea floor AUV.

  10. Dive and Explore: An Interactive Web Visualization that Simulates Making an ROV Dive to an Active Submarine Volcano

    Science.gov (United States)

    Weiland, C.; Chadwick, W. W.

    2004-12-01

    Several years ago we created an exciting and engaging multimedia exhibit for the Hatfield Marine Science Center that lets visitors simulate making a dive to the seafloor with the remotely operated vehicle (ROV) named ROPOS. The exhibit immerses the user in an interactive experience that is naturally fun but also educational. The public display is located at the Hatfield Marine Science Visitor Center in Newport, Oregon. We are now completing a revision to the project that will make this engaging virtual exploration accessible to a much larger audience. With minor modifications we will be able to put the exhibit onto the world wide web so that any person with internet access can view and learn about exciting volcanic and hydrothermal activity at Axial Seamount on the Juan de Fuca Ridge. The modifications address some cosmetic and logistic ISSUES confronted in the museum environment, but will mainly involve compressing video clips so they can be delivered more efficiently over the internet. The web version, like the museum version, will allow users to choose from 1 of 3 different dives sites in the caldera of Axial Volcano. The dives are based on real seafloor settings at Axial seamount, an active submarine volcano on the Juan de Fuca Ridge (NE Pacific) that is also the location of a seafloor observatory called NeMO. Once a dive is chosen, then the user watches ROPOS being deployed and then arrives into a 3-D computer-generated seafloor environment that is based on the real world but is easier to visualize and navigate. Once on the bottom, the user is placed within a 360 degree panorama and can look in all directions by manipulating the computer mouse. By clicking on markers embedded in the scene, the user can then either move to other panorama locations via movies that travel through the 3-D virtual environment, or they can play video clips from actual ROPOS dives specifically related to that scene. Audio accompanying the video clips informs the user where they are

  11. The Keelung Submarine Volcano in the near-shore area of northern Taiwan and its tectonic implication

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    Tsai, Ching-Hui; Hsu, Shu-Kun; Lin, Shiao-Shan; Yang, Tsanyao F.; Wang, Shiou-Ya; Doo, Wen-Bin; Lee, Hsiao-Fen; Lan, Tefang; Huang, Jian-Cheng; Liang, Chin-Wei

    2017-11-01

    The Taiwan mountain belt has been created due to the collision between the Philippine Sea Plate and the Eurasian Plate. Northernmost Taiwan and its offshore area are now under post-collisional collapse. The post-collisional magmatism is distributed around northern Taiwan. Here we first report a submarine volcano, named Keelung Submarine Volcano, existing in the near-shore area of northern Taiwan. The high 3He/4He ratios in the collected seawater samples suggest that the magma of the Keelung Submarine Volcano is derived from a mantle source. Geometrically, both the Keelung Submarine Volcano and the Tatun Volcano Group are situated above the western border of the subducted Philippine Sea Plate and may have a same magma source. Both volcanic areas belong to the northern Taiwan volcanic zone, instead of the Ryukyu volcanic front. The Keelung Submarine Volcano has been rotated clockwise ∼48° after its formation, which implies that the Keelung Submarine Volcano has formed before the Luzon arc collided against northern Taiwan. Consequently, the post-collisional model to explain the formation of the northern Taiwan volcanic zone is questionable. As indicated by numerous shallow earthquakes and persistent emissions of the volcanic gases out of the seafloor around the volcanic cone, the Keelung Submarine Volcano is as active as the Tatun Volcano Group. For the sake of volcanic hazard assessment, it is essential to monitor the activity of the Keelung Submarine Volcano.

  12. Submarine explosive activity and ocean noise generation at Monowai Volcano, Kermadec Arc: constraints from hydroacoustic T-waves

    OpenAIRE

    Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony

    2016-01-01

    Submarine volcanic activity is difficult to detect, because eruptions at depth are strongly attenuated by seawater. With increasing depth the ambient water pressure increases and limits the expansion of gas and steam such that volcanic eruptions tend to be less violent and less explosive with depth. Furthermore, the thermal conductivity and heat capacity of water causes rapid cooling of ejected products and hence erupted magma cools much more quickly than during subaerial eruptions. Therefore...

  13. Chemical Fluxes from a Recently Erupted Submarine Volcano on the Mariana Arc

    Science.gov (United States)

    Buck, N. J.; Resing, J. A.; Lupton, J. E.; Larson, B. I.; Walker, S. L.; Baker, E. T.

    2016-12-01

    While hydrothermal circulation is paramount to the geochemical budget for a wide array of elements, relatively few flux estimates exist in the literature. To date most studies have concentrated on constraining global and vent-field scale inputs originating from ocean spreading ridges. The goal of this study is to directly measure the chemical flux from an active submarine volcano injecting hydrothermal fluids into the surface ocean. Ahyi Seamount, a submarine intraoceanic arc volcano located in the Northern Mariana Islands, has a summit depth TSM and total and dissolved Fe and Mn. Laboratory analyses found enriched concentrations of H2, 3He, CO2 and Fe, consistent with a recent eruption. Preliminary flux calculations estimate a Fe input of 16 mmol s-1. This indicates shallow submarine arc volcanoes are capable of supplying appreciable quantities of Fe into the surface ocean. Further laboratory analyses and calculations to characterize and constrain the fluxes of other chemical constituents are underway.

  14. Activation of gas bubble emissions indicated by the upward decreasing Lead-210 activity at a submarine mud volcano (TY1) offshore southwestern Taiwan

    Science.gov (United States)

    Hiruta, Akihiro; Yang, Tsanyao Frank; Lin, Saulwood; Su, Chih-Chieh; Chen, Nai-Chen; Chen, Yi-Jyun; Chen, Hsuan-Wen; Yang, Tsung-Han; Huang, Yu-Chun; Wei, Kuo-Yen; Huang, Jyh-Jaan; Chen, Song-Chuen; Song, Sheng-Rong

    2017-11-01

    A submarine mud volcano (MV) known as TY1 is one of the largest conical structures found offshore southwestern Taiwan. Active gas bubble emissions at the flat crest of the mud volcano disperse sediment particles into the water column. Changes in the mud volcanism of TY1 were revealed by radiograph and grain size analysis of the sediment cores. 210Pb geochronology was applied to the near-seafloor sediments to reveal the detailed mud volcanism from the deposition rate. In a 58-cm long sediment core taken from the northern margin of the crest, known as TY1-N.170, the size and frequency of the mud clasts decrease upward. The clasts are smaller than 8 mm above a sediment depth of 34 cm below the sea floor (cmbsf). Sediments between 0 and 19 cmbsf are massive, and particles larger than 2 mm are absent. An enrichment of coarse, silt-sized particles in the massive sediment unit and the restricted distribution of the unit suggest that the massive unit was generated by re-deposition of sediment particles that were dispersed into the water column by gas bubble emission. These characteristics suggest that during the last mud volcanism of TY1, there was a decrease in mud eruption energy, and gas bubble emission became the main activity. In core TY1-S.440, taken from the southern slope, a massive sediment unit enriched with coarse, silt-sized particles, is intercalated between mud breccia structures. This suggests repeated mud breccia flows caused by TY1. The excess 210Pb activity present in the massive sediment unit of TY1-N.170 suggests activation of gas bubble emission. In the massive unit, a decrease in excess 210Pb activity appears upward toward the seafloor. The highest value is 3.1 dpm/g at 19.8 cmbsf (26.4 g/cm2 in cumulative mass); values lower than 1.0 dpm/g are distributed 2.8-6.8 cmbsf (3.6-8.8 g/cm2). The upwardly decreasing trend is opposite that of the reference core from which a reasonable areal sedimentation rate was obtained using a constant-flux constant

  15. Microbial community differentiation between active and inactive sulfide chimneys of the Kolumbo submarine volcano, Hellenic Volcanic Arc.

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    Christakis, Christos A; Polymenakou, Paraskevi N; Mandalakis, Manolis; Nomikou, Paraskevi; Kristoffersen, Jon Bent; Lampridou, Danai; Kotoulas, Georgios; Magoulas, Antonios

    2018-01-01

    Over the last decades, there has been growing interest about the ecological role of hydrothermal sulfide chimneys, their microbial diversity and associated biotechnological potential. Here, we performed dual-index Illumina sequencing of bacterial and archaeal communities on active and inactive sulfide chimneys collected from the Kolumbo hydrothermal field, situated on a geodynamic convergent setting. A total of 15,701 OTUs (operational taxonomic units) were assigned to 56 bacterial and 3 archaeal phyla, 133 bacterial and 16 archaeal classes. Active chimney communities were dominated by OTUs related to thermophilic members of Epsilonproteobacteria, Aquificae and Deltaproteobacteria. Inactive chimney communities were dominated by an OTU closely related to the archaeon Nitrosopumilus sp., and by members of Gammaproteobacteria, Deltaproteobacteria, Planctomycetes and Bacteroidetes. These lineages are closely related to phylotypes typically involved in iron, sulfur, nitrogen, hydrogen and methane cycling. Overall, the inactive sulfide chimneys presented highly diverse and uniform microbial communities, in contrast to the active chimney communities, which were dominated by chemolithoautotrophic and thermophilic lineages. This study represents one of the most comprehensive investigations of microbial diversity in submarine chimneys and elucidates how the dissipation of hydrothermal activity affects the structure of microbial consortia in these extreme ecological niches.

  16. SUBMARINE VOLCANO CHARACTERISTICS IN SABANG WATERS

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    Hananto Kurnio

    2017-07-01

    Full Text Available The aim of the study is to understand the characteristics of a volcano occurred in marine environment, as Weh Island where Sabang City located is still demonstrated its volcanic cone morphology either through satellite imagery or bathymetric map. Methods used were marine geology, marine geophysics and oceanography. Results show that surface volcanism (sea depth less than 50 m take place as fumaroles, solfataras, hot ground, hot spring, hot mud pool and alteration in the vicinities of seafloor and coastal area vents. Seismic records also showed acoustic turbidity in the sea water column due to gas bubblings produced by seafloor fumaroles. Geochemical analyses show that seafloor samples in the vicinities of active and non-active fumarole vent are abundances with rare earth elements (REE. These were interpreted that the fumarole bring along REE through its gases and deposited on the surrounding seafloor surface. Co-existence between active fault of Sumatra and current volcanism produce hydrothermal mineralization in fault zone as observed in Serui and Pria Laot-middle of Weh Island which both are controlled by normal faults and graben.

  17. Breathing modes of Kolumbo submarine volcano (Santorini, Greece).

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    Bakalis, Evangelos; Mertzimekis, Theo J; Nomikou, Paraskevi; Zerbetto, Francesco

    2017-04-13

    Submarine volcanoes, such as Kolumbo (Santorini, Greece) are natural laboratories for fostering multidisciplinary studies. Their investigation requires the most innovative marine technology together with advanced data analysis. Conductivity and temperature of seawater were recorded directly above Kolumbo's hydrothermal vent system. The respective time series have been analyzed in terms of non-equilibrium techniques. The energy dissipation of the volcanic activity is monitored by the temperature variations of seawater. The venting dynamics of chemical products is monitored by water conductivity. The analysis of the time series in terms of stochastic processes delivers scaling exponents with turning points between consecutive regimes for both conductivity and temperature. Changes of conductivity are shown to behave as a universal multifractal and their variance is subdiffusive as the scaling exponents indicate. Temperature is constant over volcanic rest periods and a universal multifractal behavior describes its changes in line with a subdiffusive character otherwise. The universal multifractal description illustrates the presence of non-conservative conductivity and temperature fields showing that the system never retains a real equilibrium state. The existence of a repeated pattern of the combined effect of both seawater and volcanic activity is predicted. The findings can shed light on the dynamics of chemical products emitted from the vents and point to the presence of underlying mechanisms that govern potentially hazardous, underwater volcanic environments.

  18. Breathing modes of Kolumbo submarine volcano (Santorini, Greece)

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    Bakalis, Evangelos; Mertzimekis, Theo J.; Nomikou, Paraskevi; Zerbetto, Francesco

    2017-04-01

    Submarine volcanoes, such as Kolumbo (Santorini, Greece) are natural laboratories for fostering multidisciplinary studies. Their investigation requires the most innovative marine technology together with advanced data analysis. Conductivity and temperature of seawater were recorded directly above Kolumbo’s hydrothermal vent system. The respective time series have been analyzed in terms of non-equilibrium techniques. The energy dissipation of the volcanic activity is monitored by the temperature variations of seawater. The venting dynamics of chemical products is monitored by water conductivity. The analysis of the time series in terms of stochastic processes delivers scaling exponents with turning points between consecutive regimes for both conductivity and temperature. Changes of conductivity are shown to behave as a universal multifractal and their variance is subdiffusive as the scaling exponents indicate. Temperature is constant over volcanic rest periods and a universal multifractal behavior describes its changes in line with a subdiffusive character otherwise. The universal multifractal description illustrates the presence of non-conservative conductivity and temperature fields showing that the system never retains a real equilibrium state. The existence of a repeated pattern of the combined effect of both seawater and volcanic activity is predicted. The findings can shed light on the dynamics of chemical products emitted from the vents and point to the presence of underlying mechanisms that govern potentially hazardous, underwater volcanic environments.

  19. Environmental monitoring of El Hierro Island submarine volcano, by combining low and high resolution satellite imagery

    Science.gov (United States)

    Eugenio, F.; Martin, J.; Marcello, J.; Fraile-Nuez, E.

    2014-06-01

    El Hierro Island, located at the Canary Islands Archipelago in the Atlantic coast of North Africa, has been rocked by thousands of tremors and earthquakes since July 2011. Finally, an underwater volcanic eruption started 300 m below sea level on October 10, 2011. Since then, regular multidisciplinary monitoring has been carried out in order to quantify the environmental impacts caused by the submarine eruption. Thanks to this natural tracer release, multisensorial satellite imagery obtained from MODIS and MERIS sensors have been processed to monitor the volcano activity and to provide information on the concentration of biological, chemical and physical marine parameters. Specifically, low resolution satellite estimations of optimal diffuse attenuation coefficient (Kd) and chlorophyll-a (Chl-a) concentration under these abnormal conditions have been assessed. These remote sensing data have played a fundamental role during field campaigns guiding the oceanographic vessel to the appropriate sampling areas. In addition, to analyze El Hierro submarine volcano area, WorldView-2 high resolution satellite spectral bands were atmospherically and deglinted processed prior to obtain a high-resolution optimal diffuse attenuation coefficient model. This novel algorithm was developed using a matchup data set with MERIS and MODIS data, in situ transmittances measurements and a seawater radiative transfer model. Multisensor and multitemporal imagery processed from satellite remote sensing sensors have demonstrated to be a powerful tool for monitoring the submarine volcanic activities, such as discolored seawater, floating material and volcanic plume, having shown the capabilities to improve the understanding of submarine volcanic processes.

  20. New Mapping of Mariana Submarine Volcanoes with Sidescan and Multibeam Sonars

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    Embley, R. W.; Chadwick, W. W.; Baker, E. T.; Johnson, P. D.; Merle, S. G.; Ristau, S.

    2003-12-01

    An expedition in February/March 2003 on the R/V Thomas G. Thompson mapped more than 18,000 km2 with the towed MR1 sidescan sonar and almost 28,000 km2 with an EM300 hull-mounted multibeam system along the Mariana volcanic arc. The expedition was funded by NOAA's Office of Ocean Exploration (more on the expedition can be found at: http://oceanexplorer.noaa.gov/explorations/03fire/welcome.html). The MR1 sidescan surveys began at the northern end of a 2001 R/V Melville MR1 survey at 16§ N and extended to Nikko Volcano at 23\\deg 05'N. A portion of the southern back-arc spreading center and the arc volcanoes south of 16\\deg N were mapped using the EM300 system. Of 43 submarine arc volcanoes surveyed that have basal diameters of 10 km or greater, 17 have summit calderas or craters. Of these, however, only 5 have diameters more than 2 km. In an accompanying survey of hydrothermal activity along the arc, CTD casts and/or tows were conducted over more than 50 individual volcanoes. The 11 volcanoes with active hydrothermal systems found in the course of these surveys appear to be about equally divided between those with and without summit calderas or craters (for additional information, see Baker et al., Resing et al., and Lupton et al., this session). The flanks of the submarine volcanoes and islands of the central and northern Mariana Arc consist largely of volcaniclastic flows. Most of the larger edifices have high-backscatter spoke-like patterns that probably represent coarser and/or younger flows from the summits. Higher relief high-backscatter areas, also commonly exhibiting a radial pattern, are found on many of the volcanoes' flanks. These are probably lava flows erupted along radial fissures. The Mariana Arc volcanoes are shedding large volumes of volcaniclastic material westward into the back-arc basin through a series of deep-sea channels oriented transverse to the arc that are in many places fed by flows from several volcanoes. On many of the volcaniclastic

  1. Sabang Submarine Volcano Aceh, Indonesia: Review of Some Trace and Rare Earth Elements Abundances Produced by Seafloor Fumarole Activities

    Directory of Open Access Journals (Sweden)

    Hananto kurnio

    2016-11-01

    Full Text Available DOI:10.17014/ijog.3.3.173-182Geochemical analyses of selected coastal and seafloor samples from Sabang Area revealed abundances of trace and rare earth elements. The selected samples of element abundances were mostly taken from seafloor in the vicinities of active fumaroles either by grab sampler operated from survey boat above fumarole point or by diver directly took the samples on the seafloor especially at Serui - Sabang Bay. Results show that samples closed to seafloor fumaroles demonstrate plenty of trace and rare earth elements. The trace and rare earth elements mean values (n=10 are: Nb (4.33 ppm, La (16.52 ppm, Ce (38.82 ppm, Nd (19.15 ppm, Ce (38.82 ppm, Pr (4.907 ppm, Nd (19.15 ppm, Sm (4.04 ppm, Gd (3.95 ppm, Dy (3.38 ppm, Th (6.432 ppm, and U (4.335 ppm. Negatively, statistical correlations between Fe, Zn, and Ni as the main sulphide elements with sulphur is interpreted that sulphide minerals do not form in the Sabang Sea. Sea water influence in the mineralization process was shown by the good correlations between Fe, Zn, Pb, Ni, and Ba.

  2. Methane concentration inside a submarine mud volcano examined through seismic velocity profiles

    Science.gov (United States)

    Kioka, Arata; Tsuji, Takeshi; Otsuka, Hironori; Ashi, Juichiro

    2017-04-01

    Mud volcanoes are considered to be among largest geological sources releasing hydrocarbon gases into the atmosphere. Numerous studies have revealed their origins and compositions from submarine mud volcanoes. A recent long-term observation at a submarine mud volcano sheds light on that larger volume of methane gas than expected is escaped from deep-water mud volcanoes, suggesting that the global methane flux from the seafloor is likely underestimated. Yet, estimates of the gas amount inside mud volcanoes have been still challenging, because of the difficulty of in-situ measurements. This study provides a new model to bridge methane amounts and seismic velocities in fluidized mud conduits of submarine mud volcanoes. This model is universally applicable and enables estimates of methane concentration in the mud conduits, using the seismic velocity profile derived from reflection/refraction seismic and/or downhole logging data. In this study, (1) we examine our modeled results through deep-drilling data obtained at mud volcanoes in the Olimpi mud field of the central Mediterranean Ridge accretionary margin, to evaluate the difference between in situ methane amounts and those calculated from our model, and (2) apply our model to the seismic velocity profile derived from seicmic data to estimate the methane amount inside the submarine mud volcano in the Nankai accretionary margin. Our scheme may provide an opportunity to re-estimate the total methane flux from submarine mud volcanoes.

  3. Mapping the sound field of an erupting submarine volcano using an acoustic glider.

    Science.gov (United States)

    Matsumoto, Haru; Haxel, Joseph H; Dziak, Robert P; Bohnenstiehl, Delwayne R; Embley, Robert W

    2011-03-01

    An underwater glider with an acoustic data logger flew toward a recently discovered erupting submarine volcano in the northern Lau basin. With the volcano providing a wide-band sound source, recordings from the two-day survey produced a two-dimensional sound level map spanning 1 km (depth) × 40 km(distance). The observed sound field shows depth- and range-dependence, with the first-order spatial pattern being consistent with the predictions of a range-dependent propagation model. The results allow constraining the acoustic source level of the volcanic activity and suggest that the glider provides an effective platform for monitoring natural and anthropogenic ocean sounds. © 2011 Acoustical Society of America

  4. Cyclic thermal behavior associated to the degassing process at El Hierro submarine volcano, Canary Islands.

    Science.gov (United States)

    Fraile-Nuez, E.; Santana-Casiano, J. M.; González-Dávila, M.

    2016-12-01

    One year after the ceasing of magmatic activity in the shallow submarine volcano of the island of El Hierro, significant physical-chemical anomalies produced by the degassing process as: (i) thermal anomalies increase of +0.44 °C, (ii) pH decrease of -0.034 units, (iii) total dissolved inorganic carbon, CT increase by +43.5 µmol kg-1 and (iv) total alkalinity, AT by +12.81 µmol kg-1 were still present in the area. These evidences highlight the potential role of the shallow degassing processes as a natural ecosystem-scale experiments for the study of significant effects of global change stressors on marine environments. Additionally, thermal time series obtained from a temporal yo-yo CTD study, in isopycnal components, over one of the most active points of the submarine volcano have been analyzed in order to investigate the behavior of the system. Signal processing of the thermal time series highlights a strong cyclic temperature period of 125-150 min at 99.9% confidence, due to characteristic time-scales revealed in the periodogram. These long cycles might reflect dynamics occurring within the shallow magma supply system below the island of El Hierro.

  5. Cyclic eruptions and sector collapses at Monowai submarine volcano, Kermadec arc: 1998-2007

    Science.gov (United States)

    Chadwick, W. W.; Wright, I. C.; Schwarz-Schampera, U.; Hyvernaud, O.; Reymond, D.; de Ronde, C. E. J.

    2008-10-01

    Repeated multibeam bathymetric surveys at Monowai Cone, a shallow submarine basaltic volcano and part of the Monowai Volcanic Center in the northern Kermadec arc, were conducted in 1998, 2004, and 2007. These surveys document dramatic depth changes at the volcano including negative changes up to -176 m from two sector collapses and positive changes up to +138 m from volcanic reconstruction near the summit and debris avalanche deposits downslope of the slide scars. One sector collapse occurred on the SE slope between 1998 and 2004 with a volume of ˜0.09 km3, and another occurred on the SW slope between 2004 and 2007 with a volume of ˜0.04 km3. The volume of positive depth change due to addition of volcanic material by eruption is of the same order: ˜0.05 km3 between 1998 and 2004 and ˜0.06 km3 between 2004 and 2007. During these time intervals, monitoring by the Polynesian Seismic Network detected frequent T wave swarms at Monowai, indicative of explosive eruptive activity every few months. An unusual T wave swarm on 24 May 2002 was previously interpreted as the collapse event between the 1998 and 2004 surveys, but no similarly anomalous T waves were detected between 2004 and 2007, probably because the Polynesian Seismic Network stations were acoustically shadowed from the second slide event. We interpret that the sector collapses on Monowai are caused by the unstable loading of fragmental erupted material on the summit and steep upper slopes of the volcano (>20°). Moreover, there appears to be a cyclic pattern in which recurrent eruptions oversteepen the cone and periodically lead to collapse events that transport volcaniclastic material downslope to the lower apron of the volcano. Volumetric rate calculations suggest that these two processes may be more or less in equilibrium. The repeated collapses at Monowai are relatively modest in volume (involving only 0.1-0.5% of the edifice volume), have occurred much more frequently than is estimated for larger debris

  6. Looking for Larvae Above an Erupting Submarine Volcano, NW Rota-1, Mariana Arc

    Science.gov (United States)

    Beaulieu, S.; Hanson, M.; Tunnicliffe, V.; Chadwick, W. W., Jr.; Breuer, E. R.

    2016-02-01

    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 and 2010 and ceased as of 2014. NW Rota-1 experienced a massive landslide in late 2009, decimating the habitat on the southern side of the volcano. This project looked at zooplankton tow samples taken from the water column above NW Rota-1 in 2010, searching for larvae which have the potential to recolonize the sea floor after such a major disturbance. 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 may act as sources for these larvae, but connectivity in this region of complex topography is unknown. As the microinvertebrate biodiversity in the Monument has yet to be fully characterized, our project also provides an opportunity to better describe both the zooplankton and benthic community composition in this area of the Monument.

  7. Submarine landslide triggered by eruption recorded by in-situ hydrophone at NW Rota-1 submarine volcano, Mariana Arc (Invited)

    Science.gov (United States)

    Chadwick, B.; Dziak, R. P.; Embley, R. W.; Tunnicliffe, V.; Sherrin, J.; Cashman, K. V.; Deardorff, N.

    2010-12-01

    An expedition to NW Rota-1, Mariana Arc, in March 2010 with R/V Kilo Moana and ROV Jason found that the submarine volcano (summit depth 520 m) was still erupting more or less continuously as has been observed since 2004, In addition, the expedition also discovered that a major landslide had occurred since the last visit in April 2009, demonstrating the dynamic processes of eruption, collapse, and regrowth in the submarine arc environment. The dive observations reveal the responses of the volcano’s magmatic and hydrothermal systems to such a collapse, as well as how the resident chemosynthetic biological community has responded to the event. The morphologic changes from the landslide can be quantified by comparing multibeam bathymetric surveys between 2009 and 2010. The headwall of the slide is now ~100 m north of the former summit ridge where depth changes up to -90 m occurred between surveys. The slide excavated material from the upper southern slope of the volcano to a distance of 3.5 km downslope, and deposited material between 2-8 km from the summit down to at least 2800 m on the volcano flank. The area and volume of slide deposits (positive depth changes) are 7.1 x 106 m2 and 5.3 x 107 m3, respectively, and the maximum thickness is +42 m. The area and volume of material removed by the slide (negative depth changes) are 2.2 x 106 m2 and -4.1 x 107 m3, respectively. We have found no evidence for a local tsunami generated by this event. The changes in morphology near the summit show that the landslide primarily removed loose volcaniclastic deposits that had accumulated near the active eruptive vent, exposing an underlying stock-like core of resistant intrusive rocks and massive lavas at the summit. During March 2010, there were at least 5 active eruptive vents, located along a line 200-m long, that changed between active and inactive day-to-day and even hour-to-hour, suggesting that the near-surface magmatic plumbing system was still reorganizing after the

  8. The first days of the new submarine volcano near Krakatoa

    NARCIS (Netherlands)

    Umbgrove, J.H.F.

    1926-01-01

    The geological history of the Krakatoa volcano, especially the eruption of 1883, is amply described in the great work “Krakatau” by R. D. M. Verheer (1885), the Report of the Krakatoa Committee (Royal Soc. London 1888) and in the publications of B. G. Escher (Handel. 1e Nederl. Indisch Natuurwet

  9. Acoustic response of submarine volcanoes in the Tofua Arc and northern Lau Basin to two great earthquakes

    Science.gov (United States)

    Bohnenstiehl, DelWayne R.; Dziak, Robert P.; Matsumoto, Haru; Conder, James A.

    2014-03-01

    Using a short-baseline hydrophone array, persistent volcanoacoustic sources are identified within the ambient noise field of the Lau Basin during the period between 2009 January and 2010 April. The submarine volcano West Mata and adjacent volcanic terrains, including the northern Matas and Volcano O, are the most active acoustic sources during the 15-month period of observation. Other areas of long-term activity include the Niua hydrothermal field, the volcanic islands of Hunga Ha'apai, Founalei, Niuatoputapu and Niuafo'ou, two seamounts located along the southern Tofua Arc and at least three unknown sites within the northern Lau Basin. Following the great Samoan earthquake on 2009 September 29, seven of the volcanoacoustic sources identified exhibit increases in the rate of acoustic detection. These changes persist over timescales of days-to-months and are observed up to 900 km from the earthquake hypocentre. At least one of the volcanoacoustic sources that did not respond to the 2009 Samoan earthquake exhibits an increase in detection rate following the great Mw 8.8 Chile earthquake that occurred at a distance of ˜9500 km on 2010 February 27. These observations suggest that great earthquakes may have undocumented impacts on Earth's vast submarine volcanic systems, potentially increasing the short-term flux of magma and volcanic gas into the overlying ocean.

  10. Significant discharge of CO2 from hydrothermalism associated with the submarine volcano of El Hierro Island.

    Science.gov (United States)

    Santana-Casiano, J M; Fraile-Nuez, E; González-Dávila, M; Baker, E T; Resing, J A; Walker, S L

    2016-05-09

    The residual hydrothermalism associated with submarine volcanoes, following an eruption event, plays an important role in the supply of CO2 to the ocean. The emitted CO2 increases the acidity of seawater. The submarine volcano of El Hierro, in its degasification stage, provided an excellent opportunity to study the effect of volcanic CO2 on the seawater carbonate system, the global carbon flux, and local ocean acidification. A detailed survey of the volcanic edifice was carried out using seven CTD-pH-ORP tow-yo studies, localizing the redox and acidic changes, which were used to obtain surface maps of anomalies. In order to investigate the temporal variability of the system, two CTD-pH-ORP yo-yo studies were conducted that included discrete sampling for carbonate system parameters. Meridional tow-yos were used to calculate the amount of volcanic CO2 added to the water column for each surveyed section. The inputs of CO2 along multiple sections combined with measurements of oceanic currents produced an estimated volcanic CO2 flux = 6.0 10(5) ± 1.1 10(5 )kg d(-1) which is ~0.1% of global volcanic CO2 flux. Finally, the CO2 emitted by El Hierro increases the acidity above the volcano by ~20%.

  11. Significant discharge of CO2 from hydrothermalism associated with the submarine volcano of El Hierro Island

    Science.gov (United States)

    Santana-Casiano, J. M.; Fraile-Nuez, E.; González-Dávila, M.; Baker, E. T.; Resing, J. A.; Walker, S. L.

    2016-05-01

    The residual hydrothermalism associated with submarine volcanoes, following an eruption event, plays an important role in the supply of CO2 to the ocean. The emitted CO2 increases the acidity of seawater. The submarine volcano of El Hierro, in its degasification stage, provided an excellent opportunity to study the effect of volcanic CO2 on the seawater carbonate system, the global carbon flux, and local ocean acidification. A detailed survey of the volcanic edifice was carried out using seven CTD-pH-ORP tow-yo studies, localizing the redox and acidic changes, which were used to obtain surface maps of anomalies. In order to investigate the temporal variability of the system, two CTD-pH-ORP yo-yo studies were conducted that included discrete sampling for carbonate system parameters. Meridional tow-yos were used to calculate the amount of volcanic CO2 added to the water column for each surveyed section. The inputs of CO2 along multiple sections combined with measurements of oceanic currents produced an estimated volcanic CO2 flux = 6.0 105 ± 1.1 105 kg d-1 which is ~0.1% of global volcanic CO2 flux. Finally, the CO2 emitted by El Hierro increases the acidity above the volcano by ~20%.

  12. The acoustic response of submarine volcanoes in the Tofua Arc and northern Lau Basin following two great earthquakes in Samoa and Chile

    Science.gov (United States)

    Bohnenstiehl, D. R.; Dziak, R. P.; Matsumoto, H.; Conder, J. A.

    2013-12-01

    Using a correlation-based detector operating on data from a short-baseline hydrophone array, persistent volcano-acoustic sources are identified within the ambient noise field of the Lau Basin during the period between January 2009 and April 2010. The submarine volcano West Mata and adjacent volcanic terrains, including the northern Matas and Volcano O, are the most active acoustic sources during the 15-month period of observation. Other areas of long-term activity include the Niua hydrothermal field, the volcanic islands of Hunga-Ha'apai, Founalei, Niuatoputapu and Niuafo'ou, two unnamed seamounts located along the southern Tofua Arc, and at least three unknown sites within the northern Lau Basin. Following the great Samoan earthquake on 29 September of 2009, seven of the volcano-acoustic sources identified exhibit increases in the rate of acoustic detection. These changes persist over time scales of days-to-months and are observed up to 900 km from the earthquake hypocenter. At least one of the volcano-acoustic sources that did not respond to the 2009 Samoan earthquake exhibits an increase in detection rate following the great Mw 8.8 Chile earthquake that occurred at a distance of ~9,500 km on 27 February 2010. These observations suggest that great earthquakes may have undocumented impacts on Earth's vast submarine volcanic systems, potentially increasing the short-term flux of magma and volcanic gas into the overlying ocean.

  13. The Geologic Setting of Hydrothermal Vents at Mariana Arc Submarine Volcanoes: High-Resolution Bathymetry and ROV Observations

    Science.gov (United States)

    Chadwick, W. W.; Embley, R. W.; de Ronde, C. E.; Stern, R. J.; Hein, J.; Merle, S.; Ristau, S.

    2004-12-01

    Remotely operated vehicle (ROV) dives were made at 7 submarine volcanoes between 14-23° N in the Mariana Arc in April 2004 with the ROPOS ROV. Six of these volcanoes were known to be hydrothermally active from CTD data collected during a previous expedition in March 2003: NW Rota-1, E Diamante, NW Eifuku, Daikoku, Kasuga-2, and Maug, a partly submerged caldera. The physical setting of hydrothermal venting varies widely from volcano to volcano. High-resolution bathymetric surveys of the summits of NW Rota-1 and NW Eifuku volcanoes were conducted with an Imagenex scanning sonar mounted on ROPOS. Near bottom observations during ROPOS dives were recorded with digital video and a digital still camera and the dives were navigated acoustically from the R/V Thompson using an ultra-short baseline system. The mapping and dive observations reveal the following: (1) The summits of some volcanoes have pervasive diffuse venting (NW Rota-1, Daikoku, NW Eifuku) suggesting that hydrothermal fluids are able to circulate freely within a permeable edifice. At other volcanoes, the hydrothermal venting is more localized (Kasuga-2, Maug, E Diamante), suggesting more restricted permeability pathways. (2) Some volcanoes have both focused venting at depth and diffuse venting near the summit (E Diamante, NW Eifuku). Where the hydrothermal vents are focused, fluid flow appears to be localized by massive lava outcrops that form steep cliffs and ridges, or by subsurface structures such as dikes. High-temperature (240° C) venting was only observed at E Diamante volcano, where the "Black Forest" vent field is located on the side of a constructional cone near the middle of E Diamante caldera at a depth of 350 m. On the side of an adjacent shallower cone, the venting style changed to diffuse discharge and it extended all the way up into the photic zone (167 m). At NW Eifuku, the pattern of both deep-focused and shallow-diffuse venting is repeated. "Champagne vent" is located at 1607 m, ~150 m

  14. Submarine geology of Hana Ridge and Haleakala Volcano's northeast flank, Maui

    Science.gov (United States)

    Eakins, Barry W.; Robinson, Joel E.

    2006-01-01

    We present a morphostructural analysis of the submarine portions of Haleakala Volcano and environs, based upon a 4-year program of geophysical surveys and submersible explorations of the underwater flanks of Hawaiian volcanoes that was conducted by numerous academic and governmental research organizations in Japan and the U.S. and funded primarily by the Japan Agency for Marine–Earth Science and Technology. A resulting reconnaissance geologic map features the 135-km-long Hana Ridge, the 3000 km2 Hana slump on the volcano's northeast flank, and island-surrounding terraces that are the submerged parts of volcanic shields. Hana Ridge below 2000 m water depth exhibits the lobate morphology typical of the subaqueously erupted parts of Hawaiian rift zones, with some important distinctions: namely, subparallel crestlines, which we propose result from the down-rift migration of offsets in the dike intrusion zone, and an amphitheater at its distal toe, where a submarine landslide has embayed the ridge tip. Deformation of Haleakala's northeast flank is limited to that part identified as the Hana slump, which lies downslope from the volcano's submerged shield, indicating that flank mobility is also limited in plan, inconsistent with hypothesized volcanic spreading driven by rift-zone dilation. The leading edge of the slump has transverse basins and ridges that resemble the thrust ramps of accretionary prisms, and we present a model to describe the slump's development that emphasizes the role of coastally generated fragmental basalt on gravitational instability of Haleakala's northeast flank and that may be broadly applicable to other ocean-island slumps.

  15. Mount Rainier active cascade volcano

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Fraile-Nuez, E; González-Dávila, M; Santana-Casiano, J M; Arístegui, J; Alonso-González, I J; Hernández-León, S; Blanco, M J; Rodríguez-Santana, A; Hernández-Guerra, A; Gelado-Caballero, M D; Eugenio, F; Marcello, J; de Armas, D; Domínguez-Yanes, J F; Montero, M F; Laetsch, D R; Vélez-Belchí, P; Ramos, A; Ariza, A V; Comas-Rodríguez, I; Benítez-Barrios, V M

    2012-01-01

    On October 10 2011 an underwater eruption gave rise to a novel shallow submarine volcano south of the island of El Hierro, Canary Islands, Spain. During the eruption large quantities of mantle-derived gases, solutes and heat were released into the surrounding waters. In order to monitor the impact of the eruption on the marine ecosystem, periodic multidisciplinary cruises were carried out. Here, we present an initial report of the extreme physical-chemical perturbations caused by this event, comprising thermal changes, water acidification, deoxygenation and metal-enrichment, which resulted in significant alterations to the activity and composition of local plankton communities. Our findings highlight the potential role of this eruptive process as a natural ecosystem-scale experiment for the study of extreme effects of global change stressors on marine environments.

  17. Examples of Models Fit to Magnetic Anomalies Observed Over Subaerial, Submarine, and Subglacial Volcanoes in the West Antarctic Rift System

    Science.gov (United States)

    Behrendt, J. C.; Finn, C. A.; Blankenship, D. D.

    2006-12-01

    Aeromagnetic and marine magnetic surveys over the volcanically active West Antarctic rift system, constrained by seismic reflection profiles over the Ross Sea continual shelf, and radar ice sounding surveys over the West Antarctic Ice Sheet (WAIS) allowed calculation of models fit to very high-amplitude anomalies. We present several examples: exposed 2700-m high, subaerial erupted volcano Mt Melbourne; the 750-m high source of anomaly D (Hamilton submarine volcano) in the Ross sea; and the 600-m high edifice of Mt. CASERTZ beneath the WAIS. The character of these anomalies and their sources varies greatly, and is inferred to be the result of subaerial, submarine and subglacial emplacement respectively. Mt. Melbourne erupted through the WAIS at a time when it was grounded over the Ross Sea continental shelf. Highly magnetic volcanic flows inferred to have high remanent (normal) magnetization in the present field direction produce the 600-nT positive anomaly. The flows protected the edifice above the ice from erosion. Negligible amounts of probably subglacially erupted, apparently non-magnetic hyaloclastite exist in association with Mt. Melbourne. Mt. CASERTZ is nonmagnetic and the edifice is interpreted as consisting of a transient mound of unconsolidated hyaloclastite injected into the WAIS. However Mt. CASERTZ, about 8-km diameter, overlies a 200-m high, 40-km wide highly magnetic residual edifice modeled as the top of the source (an active subglacial volcano) of a 400-nT high positive anomaly. Any former edifices comprising hyaloclastite, pillow breccia or other volcanic debris injected into the moving WAIS apparently have been removed. About 400 other high- amplitude anomalies associated with low relief (80 percent less than 200 m) edifices at the base of the ice (the tops of the sources of these steep gradient anomalies) beneath the WAIS defined by radar ice sounding have been interpreted as having former hyaloclastite edifices, which were removed by the moving

  18. CRED 10m Gridded bathymetry of the submarine volcanos between Olosega and Ta'u Islands of the Manu'a Island group, American Samoa (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry of the submarine volcanos between Olosega and Ta'u Islands of the Manu'a Island group, American Samoa This survey provides almost complete...

  19. Characteristics of Offshore Hawai';i Island Seismicity and Velocity Structure, including Lo';ihi Submarine Volcano

    Science.gov (United States)

    Merz, D. K.; Caplan-Auerbach, J.; Thurber, C. H.

    2013-12-01

    the regional velocity model (HG50; Klein, 1989) in the shallow lithosphere above 16 km depth. This is likely a result of thick deposits of volcaniclastic sediments and fractured pillow basalts that blanket the southern submarine flank of Mauna Loa, upon which Lo';ihi is currently superimposing (Morgan et al., 2003). A broad, low-velocity anomaly was observed from 20-40 km deep beneath the area of Pahala, and is indicative of the central plume conduit that supplies magma to the active volcanoes. A localized high-velocity body is observed 4-6 km deep beneath Lo';ihi's summit, extending 10 km to the North and South. Oriented approximately parallel to Lo';ihi's active rift zones, this high-velocity body is suggestive of intrusion in the upper crust, similar to Kilauea's high-velocity rift zones.

  20. Atribacteria from the Subseafloor Sedimentary Biosphere Disperse to the Hydrosphere through Submarine Mud Volcanoes

    Science.gov (United States)

    Hoshino, Tatsuhiko; Toki, Tomohiro; Ijiri, Akira; Morono, Yuki; Machiyama, Hideaki; Ashi, Juichiro; Okamura, Kei; Inagaki, Fumio

    2017-01-01

    Submarine mud volcanoes (SMVs) are formed by muddy sediments and breccias extruded to the seafloor from a source in the deep subseafloor and are characterized by the discharge of methane and other hydrocarbon gasses and deep-sourced fluids into the overlying seawater. Although SMVs act as a natural pipeline connecting the Earth’s surface and subsurface biospheres, the dispersal of deep-biosphere microorganisms and their ecological roles remain largely unknown. In this study, we investigated the microbial communities in sediment and overlying seawater at two SMVs located on the Ryukyu Trench off Tanegashima Island, southern Japan. The microbial communities in mud volcano sediments were generally distinct from those in the overlying seawaters and in the well-stratified Pacific margin sediments collected at the Peru Margin, the Juan de Fuca Ridge flank off Oregon, and offshore of Shimokita Peninsula, northeastern Japan. Nevertheless, in-depth analysis of different taxonomic groups at the sub-species level revealed that the taxon affiliated with Atribacteria, heterotrophic anaerobic bacteria that typically occur in organic-rich anoxic subseafloor sediments, were commonly found not only in SMV sediments but also in the overlying seawater. We designed a new oligonucleotide probe for detecting Atribacteria using the catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). CARD-FISH, digital PCR and sequencing analysis of 16S rRNA genes consistently showed that Atribacteria are abundant in the methane plumes of the two SMVs (0.58 and 1.5 × 104 cells/mL, respectively) but not in surrounding waters, suggesting that microbial cells in subseafloor sediments are dispersed as “deep-biosphere seeds” into the ocean. These findings may have important implications for the microbial transmigration between the deep subseafloor biosphere and the hydrosphere. PMID:28676800

  1. North Sea submarine cable disruptions and fishing activity

    NARCIS (Netherlands)

    Hintzen, N.T.; Machiels, M.A.M.

    2014-01-01

    At the North Sea seafloor, numerous submarine cables are positioned that connect telecommunication networks between countries. Worldwide, human activities cause most of the cable disruptions with fisheries accounting for nearly half of all reported faults. Due to a recent increase of submarine cable

  2. Methanoculleus sediminis sp. nov., a methanogen from sediments near a submarine mud volcano.

    Science.gov (United States)

    Chen, Sheng-Chung; Chen, Mei-Fei; Lai, Mei-Chin; Weng, Chieh-Yin; Wu, Sue-Yao; Lin, Saulwood; Yang, Tsanyao F; Chen, Po-Chun

    2015-07-01

    A mesophilic, hydrogenotrophic methanogen, strain S3Fa(T), was isolated from sediments collected by Ocean Researcher I cruise ORI-934 in 2010 near the submarine mud volcano MV4 located at the upper slope of south-west Taiwan. The methanogenic substrates utilized by strain S3Fa(T) were formate and H2/CO2 but not acetate, secondary alcohols, methylamines, methanol or ethanol. Cells of strain S3Fa(T) were non-motile, irregular cocci, 0.5-1.0 μm in diameter. The surface-layer protein showed an Mr of 128,000.The optimum growth conditions were 37 °C, pH 7.1 and 0.17 M NaCl. The DNA G+C content of the genome of strain S3Fa(T) was 62.3 mol%. Phylogenetic analysis revealed that strain S3Fa(T) was most closely related to Methanoculleus marisnigri JR1(T) (99.3% 16S rRNA gene sequence similarity). Genome relatedness between strain S3Fa(T) and Methanoculleus marisnigri JR1(T) was computed using both genome-to-genome distance analysis (GGDA) and average nucleotide identity (ANI) with values of 46.3-55.5% and 93.08%, respectively. Based on morphological, phenotypic, phylogenetic and genomic relatedness data, it is evident that strain S3Fa(T) represents a novel species of the genus Methanoculleus, for which the name Methanoculleus sediminis sp. nov. is proposed. The type strain is S3Fa(T) ( = BCRC AR10044(T) = DSM 29354(T)).

  3. Influence of hydrothermal venting on water column properties in the crater of the Kolumbo submarine volcano, Santorini volcanic field (Greece)

    Science.gov (United States)

    Christopoulou, Maria E.; Mertzimekis, Theo J.; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Carey, Steven; Mandalakis, Manolis

    2016-02-01

    The Kolumbo submarine volcano, located 7 km northeast of the island of Santorini, is part of Santorini's volcanic complex in the south Aegean Sea, Greece. Kolumbo's last eruption was in 1650 AD. However, a unique and active hydrothermal vent field has been revealed in the northern part of its crater floor during an oceanographic survey by remotely operated vehicles (ROVs) in 2006. In the present study, conductivity-temperature-depth (CTD) data collected by ROV Hercules during three oceanographic surveys onboard E/V Nautilus in 2010 and 2011 have served to investigate the distribution of physicochemical properties in the water column, as well as their behavior directly over the hydrothermal field. Additional CTD measurements were carried out in volcanic cone 3 (VC3) along the same volcanic chain but located 3 km northeast of Kolumbo where no hydrothermal activity has been detected to date. CTD profiles exhibit pronounced anomalies directly above the active vents on Kolumbo's crater floor. In contrast, VC3 data revealed no such anomalies, essentially resembling open-sea (background) conditions. Steep increases of temperature (e.g., from 16 to 19 °C) and conductivity near the maximum depth (504 m) inside Kolumbo's cone show marked spatiotemporal correlation. Vertical distributions of CTD signatures suggest a strong connection to Kolumbo's morphology, with four distinct zones identified (open sea, turbid flow, invariable state, hydrothermal vent field). Additionally, overlaying the near-seafloor temperature measurements on an X-Y coordinate grid generates a detailed 2D distribution of the hydrothermal vent field and clarifies the influence of fluid discharges in its formation.

  4. CRED 10m Gridded bathymetry of the submarine volcanos between Olosega and Ta'u Islands of the Manu'a Island group, American Samoa (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry of the submarine volcanos between Olosega and Ta'u Islands of the Manu'a Island group, American Samoa This survey provides almost complete...

  5. Viral infections stimulate the metabolism and shape prokaryotic assemblages in submarine mud volcanoes.

    Science.gov (United States)

    Corinaldesi, Cinzia; Dell'Anno, Antonio; Danovaro, Roberto

    2012-06-01

    Mud volcanoes are geological structures in the oceans that have key roles in the functioning of the global ecosystem. Information on the dynamics of benthic viruses and their interactions with prokaryotes in mud volcano ecosystems is still completely lacking. We investigated the impact of viral infection on the mortality and assemblage structure of benthic prokaryotes of five mud volcanoes in the Mediterranean Sea. Mud volcano sediments promote high rates of viral production (1.65-7.89 × 10(9) viruses g(-1) d(-1)), viral-induced prokaryotic mortality (VIPM) (33% cells killed per day) and heterotrophic prokaryotic production (3.0-8.3 μgC g(-1) d(-1)) when compared with sediments outside the mud volcano area. The viral shunt (that is, the microbial biomass converted into dissolved organic matter as a result of viral infection, and thus diverted away from higher trophic levels) provides 49 mgC m(-2) d(-1), thus fuelling the metabolism of uninfected prokaryotes and contributing to the total C budget. Bacteria are the dominant components of prokaryotic assemblages in surface sediments of mud volcanoes, whereas archaea dominate the subsurface sediment layers. Multivariate multiple regression analyses show that prokaryotic assemblage composition is not only dependant on the geochemical features and processes of mud volcano ecosystems but also on synergistic interactions between bottom-up (that is, trophic resources) and top-down (that is, VIPM) controlling factors. Overall, these findings highlight the significant role of the viral shunt in sustaining the metabolism of prokaryotes and shaping their assemblage structure in mud volcano sediments, and they provide new clues for our understanding of the functioning of cold-seep ecosystems.

  6. Viral infections stimulate the metabolism and shape prokaryotic assemblages in submarine mud volcanoes

    Science.gov (United States)

    Corinaldesi, Cinzia; Dell'Anno, Antonio; Danovaro, Roberto

    2012-01-01

    Mud volcanoes are geological structures in the oceans that have key roles in the functioning of the global ecosystem. Information on the dynamics of benthic viruses and their interactions with prokaryotes in mud volcano ecosystems is still completely lacking. We investigated the impact of viral infection on the mortality and assemblage structure of benthic prokaryotes of five mud volcanoes in the Mediterranean Sea. Mud volcano sediments promote high rates of viral production (1.65–7.89 × 109 viruses g−1 d−1), viral-induced prokaryotic mortality (VIPM) (33% cells killed per day) and heterotrophic prokaryotic production (3.0–8.3 μgC g−1 d−1) when compared with sediments outside the mud volcano area. The viral shunt (that is, the microbial biomass converted into dissolved organic matter as a result of viral infection, and thus diverted away from higher trophic levels) provides 49 mgC m−2 d−1, thus fuelling the metabolism of uninfected prokaryotes and contributing to the total C budget. Bacteria are the dominant components of prokaryotic assemblages in surface sediments of mud volcanoes, whereas archaea dominate the subsurface sediment layers. Multivariate multiple regression analyses show that prokaryotic assemblage composition is not only dependant on the geochemical features and processes of mud volcano ecosystems but also on synergistic interactions between bottom-up (that is, trophic resources) and top-down (that is, VIPM) controlling factors. Overall, these findings highlight the significant role of the viral shunt in sustaining the metabolism of prokaryotes and shaping their assemblage structure in mud volcano sediments, and they provide new clues for our understanding of the functioning of cold-seep ecosystems. PMID:22170423

  7. Volcanoes

    Science.gov (United States)

    ... other natural hazards, including earthquakes , mudflows and flash floods , rock falls and landslides , acid rain, fire , and (under special conditions) tsunamis . Active volcanoes in the U.S. are found mainly in Hawaii, Alaska and the Pacific Northwest. The danger area ...

  8. Draft Genome Sequence of Methanoculleus sediminis S3FaT, a Hydrogenotrophic Methanogen Isolated from a Submarine Mud Volcano in Taiwan.

    Science.gov (United States)

    Chen, Sheng-Chung; Chen, Mei-Fei; Weng, Chieh-Yin; Lai, Mei-Chin; Wu, Sue-Yao

    2016-04-21

    Here, we announce the genome sequence of ITALIC! Methanoculleus sediminisS3Fa(T)(DSM 29354(T)), a strict anaerobic methanoarchaeon, which was isolated from sediments near the submarine mud volcano MV4 located offshore in southwestern Taiwan. The 2.49-Mb genome consists of 2,459 predicted genes, 3 rRNAs, 48 tRNAs, and 1 ncRNA. The sequence of this novel strain may provide more information for species delineation and the roles that this strain plays in the unique marine mud volcano habitat. Copyright © 2016 Chen et al.

  9. A new species of Copepoda Harpacticoida, Xylora calyptogenae spec. n., with a carnivorous life-style from a hydrothermally active submarine volcano in the New Ireland Fore-Arc system (Papua New Guinea) with notes on the systematics of the Donsiellinae Lang, 1948

    Science.gov (United States)

    Willen, Elke

    2006-12-01

    A new species of harpacticoid copepods, Xylora calyptogenae spec. n., from Edison Seamount, a hydrothermally active submarine volcano in the New Ireland Fore-Arc system (Papua New Guinea) is described. The new species belongs to the Donsiellinae Lang, 1944, a highly specialised taxon, the members of which have previously been encountered only in association with decaying wood and/or wood-boring isopods. A closer relationship of the Donsiellinae with the Pseudotachidiidae Lang, 1936, can be stated on the basis of characteristics concerning the setation and/or segmentation of A1, A2, Mxl, Mxp, the shape of the female P5, anal somite, sexual dimorphisms on P2 and P3 and missing caudal seta I. Within the Pseudotachidiidae, the Donsiellinae again can be well characterized, e.g. by the setation and segmentation of A2, Mxl, swimming-legs, the shape of P1, female P5, male P2, sexual dimorphism and male P5. The Donsiellinae share some apomorphies with the pseudotachidiid subtaxon Paranannopinae Por, 1986: setation/segmentation of Mx, P1, A1. X. calyptogenae spec. n. is more closely related to Xylora bathyalis Hicks 1988 living in the deep sea wood substrata in New Zealand waters. Some traits of the evolutionary history of the Donsiellinae become evident, probably starting from the more primitive deep sea taxa X .calyptogenae spec. n., which lives in the hydrothermal seafloor in the absence of decaying wood, and X. bathyalis, which is found in decaying wood but not necessarily associated with the wood-boring isopod Limnoria Leach, 1814, towards the more advanced genera such as Donsiella Stephensen, 1936, which invades shallow waters and, further, clings to Limnoria, forming a close and, for the copepod, probably obligatory association. The specialised mouthparts of X. calyptogenae spec. n. seem to facilitate the grabbing and fixing of larger and/or active food items. This is confirmed by the presence of a large prey organism, presumably a copepod, consumed either alive or

  10. Earthquakes, Subaerial and Submarine Landslides, Tsunamis and Volcanoes in Aysén Fjord, Chile

    Science.gov (United States)

    Lastras, G.; Amblas, D.; Calafat-Frau, A. M.; Canals, M.; Frigola, J.; Hermanns, R. L.; Lafuerza, S.; Longva, O.; Micallef, A.; Sepulveda, S. A.; Vargas Easton, G.; Azpiroz, M.; Bascuñán, I.; Duhart, P.; Iglesias, O.; Kempf, P.; Rayo, X.

    2014-12-01

    The Aysén fjord, 65 km long and east-west oriented, is located at 45.4ºS and 73.2ºW in Chilean Patagonia. It has a maximum water depth of 345 m. It collects the inputs of Aysén, Pescado, Condor and Cuervo rivers, which drain the surrounding Patagonian Andes. The fjord is crossed by the Liquiñe-Ofqui Fault Zone, a seismically active trench parallel intra-arc fault system. On 21 April 2007, an Mw 6.2 earthquake triggered numerous subaerial and submarine landslides along the fjord flanks. Some of the subaerial landslides reached the water mass, generating tsunami-like displacement waves that flooded the adjacent coastlines, withlocal >50 m high run-ups, causing ten fatalities and damage to salmon farms. The research cruise DETSUFA on board BIO Hespérides in March 2013, aiming to characterise the landslides and their effects, mapped with great detail the submerged morphology of the fjord. Multibeam data display deformation structures created by the impact of the landslides in the inner fjord floor. Landslide material descended and accelerated down the highly sloping fjord flanks, and reached the fjord floor at 200 m water depth generating large, 10-m-deep impact depressions. Fjord floor sediment was pushed and piled up in arcuate deformation areas formed by 15-m-high compressional ridges, block fields and a narrow frontal depression. Up to six >1.5 km2 of these structures have been identified. In addition, the cruise mapped the outer fjord floor beyond the Cuervo ridge. This ridge, previously interpreted as a volcanic transverse structure, most probably acted as a limit for grounding ice in the past, as suggested by the presence of a melt-water channel. The fjord smoothens and deepens to more than 330 m forming an enclosed basin, before turning SW across a field of streamlined hills of glacial origin. Three volcanic cones, one of them forming Isla Colorada and the other two totally submerged and previously unknown, have been mapped in the outer fjord. The largest

  11. Metals emitted by the young submarine volcano Tagoro (El Hierro, Canary Islands): quantification in seawater and plankton and their potential impact

    OpenAIRE

    Oosterbaan, M. (Marijn)

    2016-01-01

    The concentrations of twenty metal elements in seawater and in plankton around the recently erupted submarine volcano Tagoro just South of the island El Hierro (Canary Islands, Spain) were investigated in order to assess their potential hazard to the marine environment. Samples of the seawater and the plankton were collected from 2013 to 2016 during the Vulcano and Vulcana monitoring cruises, using a rosette with Niskin bottles and a WP2 net (200 m mesh size). Significantly ...

  12. Characterizing Volcanic Processes using Near-bottom, High Resolution Magnetic Mapping of the Caldera and Inner Crater of the Kick'em Jenny Submarine Volcano

    Science.gov (United States)

    Ruchala, T. L.; Chen, M.; Tominaga, M.; Carey, S.

    2016-12-01

    Kick'em Jenny (KEJ) is an active submarine volcano located in the Lesser Antilles subduction zone, 7.5 km north of the Caribbean island Grenada. KEJ, known as one of the most explosive volcanoes in Caribbean, erupted 12 times since 1939 with recent eruptions in 2001 and possibly in 2015. Multiple generations of submarine landslides and canyons have been observed in which some of them can be attributed to past eruptions. The structure of KEJ can be characterized as a 1300 m high conical profile with its summit crater located around 180 m in depth. Active hydrothermal venting and dominantly CO2 composition gas seepage take place inside this 250m diameter crater, with the most activity occurring primarily within a small ( 70 x 110 m) depression zone (inner crater). In order to characterize the subsurface structure and decipher the processes of this volcanic system, the Nautilus NA054 expedition in 2014 deployed the underwater Remotely Operated Vehicle (ROV) Hercules to conduct near-bottom geological observations and magnetometry surveys transecting KEJ's caldera. Raw magnetic data was corrected for vehicle induced magnetic noise, then merged with ROV to ship navigation at 1 HZ. To extract crustal magnetic signatures, the reduced magnetic data was further corrected for external variations such as the International Geomagnetic Reference Field and diurnal variations using data from the nearby San Juan Observatory. We produced a preliminary magnetic anomaly map of KEJ's caldera for subsequent inversion and forward modeling to delineate in situ magnetic source distribution in understanding volcanic processes. We integrated the magnetic characterization of the KEJ craters with shipboard multibeam, ROV visual descriptions, and photomosaics. Initial observations show the distribution of short wavelength scale highly magnetized source centered at the north western part of the inner crater. Although locations of gas seeps are ubiquitous over the inner crater area along ROV

  13. TWO-DIMENSIONAL SIMULATIONS OF EXPLOSIVE ERUPTIONS OF KICK-EM JENNY AND OTHER SUBMARINE VOLCANOS

    Directory of Open Access Journals (Sweden)

    Galen Gisler

    2006-01-01

    Full Text Available Kick-em Jenny, in the Eastern Caribbean, is a submerged volcanic cone that has erupted a dozen or more times since its discovery in 1939. The most likely hazard posed by this volcano is to shipping in the immediate vicinity (through volcanic missiles or loss-of-buoyancy, but it is of interest to estimate upper limits on tsunamis that might be produced by a catastrophic explosive eruption. To this end, we have performed two-dimensional simulations of such an event in a geometry resembling that of Kick-em Jenny with our SAGE adaptive mesh Eulerian multifluid compressible hydrocode. We use realistic equations of state for air, water, and basalt, and follow the event from the initial explosive eruption, through the generation of a transient water cavity and the propagation of waves away from the site. We find that even for extremely catastrophic explosive eruptions, tsunamis from Kick-em Jenny are unlikely to pose significant danger to nearby islands. For comparison, we have also performed simulations of explosive eruptions at the much larger shield volcano Vailulu'u in the Samoan chain, where the greater energy available can produce a more impressive wave. In general, however, we conclude that explosive eruptions do not couple well to water waves. The waves that are produced from such events are turbulent and highly dissipative, and don't propagate well. This is consistent with what we have found previously in simulations of asteroid-impact generated tsunamis. Non-explosive events, however, such as landslides or gas hydrate releases, do couple well to waves, and our simulations of tsunamis generated by sub- aerial and sub-aqueous landslides demonstrate this.

  14. Two-dimensional simulations of explosive eruptions of Kick-em Jenny and other submarine volcanos

    Energy Technology Data Exchange (ETDEWEB)

    Gisler, Galen R.; Weaver, R. P. (Robert P.); Mader, Charles L.; Gittings, M. L. (Michael L.)

    2004-01-01

    Kick-em Jenny, in the Eastern Caribbean, is a submerged volcanic cone that has erupted a dozen or more times since its discovery in 1939. The most likely hazard posed by this volcano is to shipping in the immediate vicinity (through volcanic missiles or loss-of-buoyancy), but it is of interest to estimate upper limits on tsunamis that might be produced by a catastrophic explosive eruption. To this end, we have performed two-dimensional simulations of such an event in a geometry resembling that of Kick-em Jenny with our SAGE adaptive mesh Eulerian multifluid compressible hydrocode. We use realistic equations of state for air, water, and basalt, and follow the event from the initial explosive eruption, through the generation of a transient water cavity and the propagation of waves away from the site. We find that even for extremely catastrophic explosive eruptions, tsunamis from Kick-em Jenny are unlikely to pose significant danger to nearby islands. For comparison, we have also performed simulations of explosive eruptions at the much larger shield volcano Vailuluu in the Samoan chain, where the greater energy available can produce a more impressive wave. In general, however, we conclude that explosive eruptions do not couple well to water waves. The waves that are produced from such events are turbulent and highly dissipative, and don't propagate well. This is consistent with what we have found previously in simulations of asteroid-impact generated tsunamis. Non-explosive events, however, such as landslides or gas hydrate releases, do couple well to waves, and our simulations of tsunamis generated by subaerial and sub-aqueous landslides demonstrate this.

  15. Monitoring active volcanoes: The geochemical approach

    Directory of Open Access Journals (Sweden)

    Takeshi Ohba

    2011-06-01

    Full Text Available

    The geochemical surveillance of an active volcano aims to recognize possible signals that are related to changes in volcanic activity. Indeed, as a consequence of the magma rising inside the volcanic "plumbing system" and/or the refilling with new batches of magma, the dissolved volatiles in the magma are progressively released as a function of their relative solubilities. When approaching the surface, these fluids that are discharged during magma degassing can interact with shallow aquifers and/or can be released along the main volcano-tectonic structures. Under these conditions, the following main degassing processes represent strategic sites to be monitored.

    The main purpose of this special volume is to collect papers that cover a wide range of topics in volcanic fluid geochemistry, which include geochemical characterization and geochemical monitoring of active volcanoes using different techniques and at different sites. Moreover, part of this volume has been dedicated to the new geochemistry tools.

  16. Magnetic signature of submarine volcanoes in the Phlegrean Fields-Ischia Ridge (North-Western side of the Bay of Naples, Southern Italy

    Directory of Open Access Journals (Sweden)

    M. Secomandi

    2008-06-01

    Full Text Available This paper presents a study of the Phlegrean Fields-Ischia submarine ridge by the analysis and interpretation of high-resolution aeromagnetic data recently acquired in the Western Procida offshore. The investigated area is located along the ridge connecting Ischia to the Phlegrean Fields and is characterized by the existence of several monogenetic volcanoes aligned on a NE-SW system of faults. The high-resolution magnetic data yielded new information on the area, highlighting particularly the signature of a volcanic body located between Pt. Serra and the Ruommoli shoal. This structure has not been clearly described before and we named it as the Pt. Serra submarine volcano. The computation of the analytic signal and horizontal gradient of the data distinctly located this structure and definined the position of its rims. A 2D modeling and 3D inversion of data provided information on the volcano’s thickness, width and magnetization, disclosing a meaningful igneous body extending down to several hundred meters b.s.l.

  17. Control of Volume and Porosity on Pumice Floatation Time: A Case Study with Pumice from the Havre Submarine Caldera Volcano

    Science.gov (United States)

    Hosseini, B.; Fauria, K.; Manga, M.; Carey, R.; Soule, S. A.

    2016-12-01

    During the 2015 MESH (Mapping, Exploration, and Sampling at Havre) expedition to the submarine Havre caldera volcano, we collected pumice from the 2012 eruption. Here, we report pumice volume, porosity, and floatation time from measurements on 32 clasts (0.2-16 g) that provide insight into the eruption dynamics and mechanisms that deposited these clasts on the seafloor. We measured pumice volume using photogrammetry, capturing 100-180 images per sample. We used a series of open-source software—VisualSFM and MeshLab—to process the images and construct volume models. Combined with measurements of mass, we can determine pumice porosity. We calculated a mean porosity of 0.86+/-0.03 for the 32 samples. The lowest measured porosity of 0.78 was from a fragment of a giant 1.5-m diameter pumice clast. In addition to quantifying pumice volume and porosity, we conducted floatation experiments in which we cleaned, dried, and set the 32 samples on water and measured the time required for each clast to sink. Pumice floatation times varied from 0.8-226 days. We found that pumice floatation time scales with both pumice volume and porosity. These trends are consistent with a gas trapping mechanism for cold pumice floatation and suggest that pumice porosity, in addition to pumice volume, exerts an important control on the floatation time and fate of floating pumice. Despite the wide range of floatation times for these clasts, the proximal to vent collection suggests that these pumice (with the possible exception of the giant pumice fragment) were deposited on the seafloor soon after the 2012 eruption and never reached the ocean surface.

  18. The submarine volcano eruption off El Hierro Island: effects on the scattering migrant biota and the evolution of the pelagic communities.

    Science.gov (United States)

    Ariza, Alejandro; Kaartvedt, Stein; Røstad, Anders; Garijo, Juan Carlos; Arístegui, Javier; Fraile-Nuez, Eugenio; Hernández-León, Santiago

    2014-01-01

    The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent) of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community.

  19. The submarine volcano eruption off El Hierro Island: Effects on the scattering migrant biota and the evolution of the pelagic communities

    KAUST Repository

    Ariza, Alejandro

    2014-07-21

    The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent) of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community. © 2014 Ariza et al.

  20. The submarine volcano eruption off El Hierro Island: effects on the scattering migrant biota and the evolution of the pelagic communities.

    Directory of Open Access Journals (Sweden)

    Alejandro Ariza

    Full Text Available The submarine volcano eruption off El Hierro Island (Canary Islands on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community.

  1. Magma plumbing system and seismicity of an active mid-ocean ridge volcano.

    Science.gov (United States)

    Schmid, Florian; Schlindwein, Vera; Koulakov, Ivan; Plötz, Aline; Scholz, John-Robert

    2017-02-20

    At mid-ocean ridges volcanism generally decreases with spreading rate but surprisingly massive volcanic centres occur at the slowest spreading ridges. These volcanoes can host unexpectedly strong earthquakes and vigorous, explosive submarine eruptions. Our understanding of the geodynamic processes forming these volcanic centres is still incomplete due to a lack of geophysical data and the difficulty to capture their rare phases of magmatic activity. We present a local earthquake tomographic image of the magma plumbing system beneath the Segment 8 volcano at the ultraslow-spreading Southwest Indian Ridge. The tomography shows a confined domain of partial melt under the volcano. We infer that from there melt is horizontally transported to a neighbouring ridge segment at 35 km distance where microearthquake swarms and intrusion tremor occur that suggest ongoing magmatic activity. Teleseismic earthquakes around the Segment 8 volcano, prior to our study, indicate that the current magmatic spreading episode may already have lasted over a decade and hence its temporal extent greatly exceeds the frequent short-lived spreading episodes at faster opening mid-ocean ridges.

  2. Systematic radon survey over active volcanoes

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, J.L.; Monnin, M.; Garcia Vindas, J.R. [Centre National de la Recherche Cientifique, Montpellier (France). Lab. GBE; Ricard, L.P.; Staudacher, T. [Observatoire Volcanologique Du Pitou de la Fournaise, La Plaine des Cafres (France)

    1999-08-01

    Data obtained since 1993 on Costa Rica volcanos are presented and radon anomalies recorded before the eruption of the Irazu volcano (December 8, 1994) are discussed. The Piton de la Fournaise volcano is inactive since mid 1992. The influence of the external parameters on the radon behaviour is studied and the type of perturbations induced on short-term measurements are individuate.

  3. Dive and Explore: An Interactive Exhibit That Simulates Making an ROV Dive to a Submarine Volcano, Hatfield Marine Science Visitor Center, Newport, Oregon

    Science.gov (United States)

    Weiland, C.; Chadwick, W. W.; Hanshumaker, W.; Osis, V.; Hamilton, C.

    2002-12-01

    We have created a new interactive exhibit in which the user can sit down and simulate that they are making a dive to the seafloor with the remotely operated vehicle (ROV) named ROPOS. The exhibit immerses the user in an interactive experience that is naturally fun but also educational. This new public display is located at the Hatfield Marine Science Visitor Center in Newport, Oregon. The exhibit is designed to look like the real ROPOS control console and includes three video monitors, a PC, a DVD player, an overhead speaker, graphic panels, buttons, lights, dials, and a seat in front of a joystick. The dives are based on real seafloor settings at Axial seamount, an active submarine volcano on the Juan de Fuca Ridge (NE Pacific) that is also the location of a seafloor observatory called NeMO. The user can choose between 1 of 3 different dives sites in the caldera of Axial Volcano. Once a dive is chosen, then the user watches ROPOS being deployed and then arrives into a 3-D computer-generated seafloor environment that is based on the real world but is easier to visualize and navigate. Once on the bottom, the user is placed within a 360 degree panorama and can look in all directions by manipulating the joystick. By clicking on markers embedded in the scene, the user can then either move to other panorama locations via movies that travel through the 3-D virtual environment, or they can play video clips from actual ROPOS dives specifically related to that scene. Audio accompanying the video clips informs the user where they are going or what they are looking at. After the user is finished exploring the dive site they end the dive by leaving the bottom and watching the ROV being recovered onto the ship at the surface. The user can then choose a different dive or make the same dive again. Within the three simulated dives there are a total of 6 arrival and departure movies, 7 seafloor panoramas, 12 travel movies, and 23 ROPOS video clips. The exhibit software was created

  4. Methanogenic diversity and activity in hypersaline sediments of the centre of the Napoli mud volcano, Eastern Mediterranean Sea.

    Science.gov (United States)

    Lazar, Cassandre Sara; Parkes, R John; Cragg, Barry A; L'Haridon, Stéphane; Toffin, Laurent

    2011-08-01

    Submarine mud volcanoes are a significant source of methane to the atmosphere. The Napoli mud volcano, situated in the brine-impacted Olimpi Area of the Eastern Mediterranean Sea, emits mainly biogenic methane particularly at the centre of the mud volcano. Temperature gradients support the suggestion that Napoli is a cold mud volcano with moderate fluid flow rates. Biogeochemical and molecular genetic analyses were carried out to assess the methanogenic activity rates, pathways and diversity in the hypersaline sediments of the centre of the Napoli mud volcano. Methylotrophic methanogenesis was the only significant methanogenic pathway in the shallow sediments (0-40 cm) but was also measured throughout the sediment core, confirming that methylotrophic methanogens could be well adapted to hypersaline environments. Hydrogenotrophic methanogenesis was the dominant pathway below 50 cm; however, low rates of acetoclastic methanogenesis were also present, even in sediment layers with the highest salinity, showing that these methanogens can thrive in this extreme environment. PCR-DGGE and methyl coenzyme M reductase gene libraries detected sequences affiliated with anaerobic methanotrophs (mainly ANME-1) as well as Methanococcoides methanogens. Results show that the hypersaline conditions in the centre of the Napoli mud volcano influence active biogenic methane fluxes and methanogenic/methylotrophic diversity. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  5. Intermediate products of sulfur disproportional reaction and their physical role in effusive to explosive submarine volcanic activity

    Science.gov (United States)

    Nakamura, K.; Takano, B.; Butterfield, D. A.; Resing, J.; Chadwick, W. W.; Embley, R. W.

    2009-12-01

    Recent direct observations of submarine volcanic activity in the Mariana Arc are giving us a chance to examine the role of volcanic gas in submarine volcanic conduits. Unlike subaerial volcanoes, where hydrogeologic conditions have different character from place to place, the overlying water mass above submarine volcanoes gives a uniform hydrographic setting. Currently, the places where we can directly observe submarine volcanic activity are located deeper than 400 m, which raises the boiling point of seawater to over 240 deg C. This situation allows us to examine the interaction of volcanic gases with ambient seawater at a shorter distance from the magma source than at subaerial volcanic settings. Arc volcano settings give us longer and more frequent opportunities to make observations and provide a more diverse range of submarine volcanism than ridge settings. Among the three major components of volcanic gases (i.e., H2O, CO2 and SO2), water follows a two phase boundary below the critical temperature after volatile components leave from the magmatic source. Milky sulfur sol bearing hydrothermal fluid is commonly observed throughout Mariana active sites. Most of the sulfur sol (colloidal elemental sulfur and polysulfides) might be formed by disproportional reaction of sulfur dioxide with seawater when water vapor shrinks to liquid water. The reaction creates not only sulfur sol but also various types of sulfite, which affects the pH of seawater. We detected short-lived sulfite species in the water column above several active Mariana volcanoes such as NW Rota-1, Daikoku and Nikko by on-board HPLC. Because most observations are made on the liquid phase side of H2O boundary, it is very hard to get data to investigate the physical and chemical sulfur sol forming process occurring on the vapor phase side or at the critical state (i.e., near the magma source process). Carbon dioxide behaves as a gas at a wide range of pressures and temperatures and carries heat and

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

    Science.gov (United States)

    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

  7. CO2 and H2O Contents of Melt Inclusions from the 1891 Basaltic Balloon Eruption of Foerstner Submarine Volcano, Italy

    Science.gov (United States)

    Balcanoff, J. R.; Carey, S.; Kelley, K. A.; Boesenberg, J. S.

    2016-12-01

    Eruptions that produce basaltic balloon products are an uncommon eruption style only observed in five cases during historical times. Basaltic balloon products form in gas rich shallow submarine eruptions, which produce large hollow clasts with sufficient buoyancy to float on seawater. Foerstner submarine volcano, off the coast of Pantelleria (Italy), erupted with this style in 1891 and is the only eruption where the vent site (250 m water depth) has been studied and sampled in detail with remotely operated vehicles (ROVs). Here, we report Fournier Transform Infrared Spectroscopy (FTIR) and electron microprobe (EMP) analyses of major elements and dissolved volatiles in melt inclusions from olivine and plagioclase phenocrysts picked from highly vesicular clasts recovered from the seafloor. The trachybasaltic melt is enriched in alkalis with notably high phosphorus (1.82-2.38 wt%), and melt inclusions show elevated H2O concentrations of 0.17 to 1.2 wt.% and highly elevated CO2 concentrations of 928 to 1864 ppm. Coexisting matrix glass is completely degassed with respect to carbon dioxide but has variable water contents up to 0.19 %. The maximum carbon dioxide value implies saturation at 1.5 kb, or 4.5 km below the volcano. Trends in the CO2 and H2O data are most compatible with calculated open system degassing behavior. This is consistent with a proposed balloon formation mechanism involving a hybrid strombolian eruption style with the potential accumulation of gas-rich pockets below the vent as gas bubbles moved upwards independent of the low viscosity basaltic melt. Discharge of the gas-rich pockets led to the discharge of meter-sized slugs of magma with large internal vesicles (several tens of centimeters). A subset of these clasts had bulk densities that were lower than seawater, allowing them to rise to the sea surface where they either exploded or became water saturated and sank back to the seafloor.

  8. Evolution of submarine eruptive activity during the 2011-2012 El Hierro event as documented by hydroacoustic images and remotely operated vehicle observations

    Science.gov (United States)

    Somoza, L.; González, F. J.; Barker, S. J.; Madureira, P.; Medialdea, T.; de Ignacio, C.; Lourenço, N.; León, R.; Vázquez, J. T.; Palomino, D.

    2017-08-01

    Submarine volcanic eruptions are frequent and important events, yet they are rarely observed. Here we relate bathymetric and hydroacoustic images from the 2011 to 2012 El Hierro eruption with surface observations and deposits imaged and sampled by ROV. As a result of the shallow submarine eruption, a new volcano named Tagoro grew from 375 to 89 m depth. The eruption consisted of two main phases of edifice construction intercalated with collapse events. Hydroacoustic images show that the eruptions ranged from explosive to effusive with variable plume types and resulting deposits, even over short time intervals. At the base of the edifice, ROV observations show large accumulations of lava balloons changing in size and type downslope, coinciding with the area where floating lava balloon fallout was observed. Peaks in eruption intensity during explosive phases generated vigorous bubbling at the surface, extensive ash, vesicular lapilli and formed high-density currents, which together with periods of edifice gravitational collapse, produced extensive deep volcaniclastic aprons. Secondary cones developed in the last stages and show evidence for effusive activity with lava ponds and lava flows that cover deposits of stacked lava balloons. Chaotic masses of heterometric boulders around the summit of the principal cone are related to progressive sealing of the vent with decreasing or variable magma supply. Hornitos represent the final eruptive activity with hydrothermal alteration and bacterial mats at the summit. Our study documents the distinct evolution of a submarine volcano and highlights the range of deposit types that may form and be rapidly destroyed in such eruptions.Plain Language SummaryToday and through most of geological history, the greatest number and volume of volcanic eruptions on Earth have occurred underwater. However, in comparison to subaerial eruption, little is known about submarine eruptive processes as they are dangerous to cruise it over

  9. Distribution of trace elements including tellurium, gallium, indium, and select REE in sulfide chimneys from Brothers submarine volcano, Kermadec arc

    Science.gov (United States)

    Berkenbosch, H. A.; de Ronde, C. E.; McNeill, A.; Goemann, K.; Gemmell, J. B.

    2011-12-01

    Brothers volcano is a dacitic volcano located along the Kermadec arc, New Zealand, and hosts the NW Caldera hydrothermal vent field perched on part of the steep caldera walls. The field strikes for ~600 m between depths of 1550 and 1700 m and includes numerous, active, high-temperature (max 302°C) chimneys and even more dead, sulfide-rich spires. Chimney samples collected from Brothers show distinct mineralogical zonation reflecting gradients in oxidation state, temperature, and pH from the inner walls in contact with hydrothermal fluids through to the outer walls in contact with seawater. Minerals deposited from hotter fluids (e.g., chalcopyrite) are located in the interior of the chimneys and are surrounded by an external zone of minerals deposited by cooler fluids (e.g., sulfates, sphalerite). Four chimneys types are identified at Brothers volcano based on the relative proportions of chalcopyrite and sulfate layers, and the presence or absence of anhydrite. Two are Cu-rich, i.e., chalcopyrite-rich and chalcopyrite-bornite-rich chimneys, and two are Zn-rich, i.e., sphalerite-rich and sphalerite-chalcopyrite-rich. Barite and anhydrite are common to both Cu-rich chimney types whereas Zn-rich chimneys contain barite only. The main mineral phases in all the chimneys are anhydrite, barite, chalcopyrite, pyrite/marcasite, and sphalerite. Trace minerals include galena, covellite, tennantite, realgar, chalcocite, bornite, hematite, goethite, Pb-As sulfosalts, and Bi- or Au-tellurides. The vast majority of tellurides are <5 μm in size, although columnar crystals up to 80 μm long have been observed. The tellurides commonly form in bands, cluster in patches, or occur along internal grain boundaries within chalcopyrite. They also are found at the contact between chalcopyrite and pyrite grains. In sulfate layers adjacent to the chalcopyrite zones tellurides can occur as inclusions in anhydrite, barite or pyrite and/or occupy void space within the chimney. One Cu

  10. Determining the stress field in active volcanoes using focal mechanisms

    Directory of Open Access Journals (Sweden)

    Bruno Massa

    2016-11-01

    Full Text Available Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs, Campi Flegrei (217 FPSs and Long Valley Caldera (38,000 FPSs. The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  11. Determining the stress field in active volcanoes using focal mechanisms

    Science.gov (United States)

    Massa, Bruno; D'Auria, Luca; Cristiano, Elena; De Matteo, Ada

    2016-11-01

    Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs), Campi Flegrei (217 FPSs) and Long Valley Caldera (38,000 FPSs). The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  12. Linking petrology and seismology at an active volcano.

    Science.gov (United States)

    Saunders, Kate; Blundy, Jon; Dohmen, Ralf; Cashman, Kathy

    2012-05-25

    Many active volcanoes exhibit changes in seismicity, ground deformation, and gas emissions, which in some instances arise from magma movement in the crust before eruption. An enduring challenge in volcano monitoring is interpreting signs of unrest in terms of the causal subterranean magmatic processes. We examined over 300 zoned orthopyroxene crystals from the 1980-1986 eruption of Mount St. Helens that record pulsatory intrusions of new magma and volatiles into an existing larger reservoir before the eruption occurred. Diffusion chronometry applied to orthopyroxene crystal rims shows that episodes of magma intrusion correlate temporally with recorded seismicity, providing evidence that some seismic events are related to magma intrusion. These time scales are commensurate with monitoring signals at restless volcanoes, thus improving our ability to forecast volcanic eruptions by using petrology.

  13. The Active Lava Flows of Kilauea Volcano, Hawaii

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 6. The Active Lava Flows of Kilauea Volcano, Hawaii. Hetu Sheth. General Article Volume 8 Issue 6 June 2003 pp 24-33. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/008/06/0024-0033. Keywords.

  14. Submarine seismic monitoring of El Hierro volcanic eruption with a 3C-geophone string: applying new acquisition and data processing techniques to volcano monitoring

    Science.gov (United States)

    Jurado, Maria Jose; Ripepe, Maurizio; Lopez, Carmen; Blanco, Maria Jose; Crespo, Jose

    2015-04-01

    A submarine volcanic eruption took place near the southernmost emerged land of the El Hierro Island (Canary Islands, Spain), from October 2011 to February 2012. The Instituto Geografico Nacional (IGN) seismic stations network evidenced seismic unrest since July 2011 and was a reference also to follow the evolution of the seismic activity associated with the volcanic eruption. Right after the eruption onset, in October 2011 a geophone string was deployed by the CSIC-IGN to monitor seismic activity. Monitoring with the seismic array continued till May 2012. The array was installed less than 2 km away from the new vol¬cano, next to La Restinga village shore in the harbor from 6 to 12m deep into the water. Our purpose was to record seismic activity related to the volcanic activity, continuously and with special interest on high frequency events. The seismic array was endowed with 8, high frequency, 3 component, 250 Hz, geophone cable string with a separation of 6 m between them. Each geophone consists on a 3-component module based on 3 orthogonal independent sensors that measures ground velocity. Some of the geophones were placed directly on the seabed, some were buried. Due to different factors, as the irregular characteristics of the seafloor. The data was recorded on the surface with a seismometer and stored on a laptop computer. We show how acoustic data collected underwater show a great correlation with the seismic data recorded on land. Finally we compare our data analysis results with the observed sea surface activity (ash and lava emission and degassing). This evidence is disclosing new and innovative tecniques on monitoring submarine volcanic activity. Reference Instituto Geográfico Nacional (IGN), "Serie El Hierro." Internet: http://www.ign.es/ign/resources /volcanologia/HIERRO.html [May, 17. 2013

  15. Continuous gravity observations at active volcanoes through superconducting gravimeters

    Science.gov (United States)

    Carbone, Daniele; Greco, Filippo

    2016-04-01

    Continuous gravity measurements at active volcanoes are usually taken through spring gravimeters that are easily portable and do not require much power to work. However, intrinsic limitations dictate that, when used in continuous, these instruments do not provide high-quality data over periods longer than some days. Superconducting gravimeters (SG), that feature a superconducting sphere in a magnetic field as the proof mass, provide better-quality data than spring gravimeters, but are bigger and need mains electricity to work, implying that they cannot be installed close to the active structures of high volcanoes. An iGrav SG was installed on Mt. Etna (Italy) in September 2014 and has worked almost continuously since then. It was installed about 6km from the active craters in the summit zone of the volcano. Such distance is normally too much to observe gravity changes due to relatively fast (minutes to days) volcanic processes. Indeed, mass redistributions in the shallowest part of the plumbing system induce short-wavelength gravity anomalies, centered below the summit craters. Nevertheless, thanks to the high precision and long-term stability of SGs, it was possible to observe low-amplitude changes over a wide range of timescales (minutes to months), likely driven by volcanic activity. Plans are in place for the implementation of a mini-array of SGs at Etna.

  16. Physical activity aboard nuclear submarines as measured by pedometry. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Bondi, K.R.; Dougherty, J.H.

    1985-05-23

    Activity levels of 44 submarines were monitored before and during a fleet ballistic missile submarine patrol. These levels were determined by use of a pedometer worn on the hip. Readings were obtained daily and recorded in a log as miles walked. Through extensive preliminary testing it was determined that the miles unit was useless, due to variability in the sensitivity of the pedometer pendulum movements and the inability to determine a meaningful stride length . Results for any combination of pedometer/user were, however, repeatable. For lack of a better term, results are reported in miles per day and are as follows: Control = 2.11 + or - 0.32 and Underway = 1.01 + or - 0.27 (P<.05 Student T). This reduction of more than 50% in activity level may in part be responsible for the physical deconditioning observed during the course of a 40-70 day submergence period.

  17. ESR dating of submarine hydrothermal activities using barite in sulfide deposition

    Science.gov (United States)

    Toyoda, S.; Fujiwara, T.; Ishibashi, J.; Isono, Y.; Uchida, A.; Takamasa, A.; Nakai, S.

    2012-12-01

    The temporal change of submarine hydrothermal activities has been an important issue in the aspect of the evolution of hydrothermal systems which is related with ore formation (Urabe, 1995) and biological systems sustained by the chemical species arising from hydrothermal activities (Macdonald et al., 1980). Determining the ages of the hydrothermal deposit will provide essential information on such studies. Dating methods using disequilibrium between radioisotopes such as U-Th method (e.g. You and Bickle, 1998), 226}Ra-{210Pb and 228}Ra-{228Th method (e.g. Noguchi et al., 2011) have been applied to date submarine hydrothermal deposits. ESR (electron spin resonance) dating method is commonly applied to fossil teeth, shells, and quartz of Quaternay period where the natural accumulated dose is obtained from the intensities of the ESR signals which are created by natural radiation. The natural dose is divided by the dose rate to the mineral/sample to deduce the age. Okumura et al., (2010) made the first practical application of ESR (electron spin resonance) dating technique to a sample of submarine hydrothermal barite (BaSO4) to obtain preliminary ages, where Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. Knowing that ESR dating of barite is promising, in this paper, we will present how we have investigated each factor that contributes ESR dating of barite in submarine hydrothermal sulfide deposition. (1) The best ESR condition for measuring the SO3- signal in barite is with the microwave power of 1mW and modulation amplitude of 0.1mT. (2) As results of heating experiments, the signal was found to be stable for the dating age range of several thousands. (3) 226Ra replacing Ba in barite is the source of the radiation. The amount of radioactive elements in sulfide mineral surrounding barite is negligible. (4) The external radiation from the sea water is negligible even in the submarine hydrothermal area where the radiation level is much

  18. Monitoring Active Volcanos Using Aerial Images and the Orthoview Tool

    Directory of Open Access Journals (Sweden)

    Maria Marsella

    2014-12-01

    Full Text Available In volcanic areas, where it can be difficult to perform direct surveys, digital photogrammetry techniques are rarely adopted for routine volcano monitoring. Nevertheless, they have remarkable potentialities for observing active volcanic features (e.g., fissures, lava flows and the connected deformation processes. The ability to obtain accurate quantitative data of definite accuracy in short time spans makes digital photogrammetry a suitable method for controlling the evolution of rapidly changing large-area volcanic phenomena. The systematic acquisition of airborne photogrammetric datasets can be adopted for implementing a more effective procedure aimed at long-term volcano monitoring and hazard assessment. In addition, during the volcanic crisis, the frequent acquisition of oblique digital images from helicopter allows for quasi-real-time monitoring to support mitigation actions by civil protection. These images are commonly used to update existing maps through a photo-interpretation approach that provide data of unknown accuracy. This work presents a scientific tool (Orthoview that implements a straightforward photogrammetric approach to generate digital orthophotos from single-view oblique images provided that at least four Ground Control Points (GCP and current Digital Elevation Models (DEM are available. The influence of the view geometry, of sparse and not-signalized GCP and DEM inaccuracies is analyzed for evaluating the performance of the developed tool in comparison with other remote sensing techniques. Results obtained with datasets from Etna and Stromboli volcanoes demonstrate that 2D features measured on the produced orthophotos can reach sub-meter-level accuracy.

  19. A Broadly-Based Training Program in Volcano Hazards Monitoring at the Center for the Study of Active Volcanoes

    Science.gov (United States)

    Thomas, D. M.; Bevens, D.

    2015-12-01

    The Center for the Study of Active Volcanoes, in cooperation with the USGS Volcano Hazards Program at HVO and CVO, offers a broadly based volcano hazards training program targeted toward scientists and technicians from developing nations. The program has been offered for 25 years and provides a hands-on introduction to a broad suite of volcano monitoring techniques, rather than detailed training with just one. The course content has evolved over the life of the program as the needs of the trainees have changed: initially emphasizing very basic monitoring techniques (e.g. precise leveling, interpretation of seismic drum records, etc.) but, as the level of sophistication of the trainees has increased, training in more advanced technologies has been added. Currently, topics of primary emphasis have included volcano seismology and seismic networks; acquisition and modeling of geodetic data; methods of analysis and monitoring of gas geochemistry; interpretation of volcanic deposits and landforms; training in LAHARZ, GIS mapping of lahar risks; and response to and management of volcanic crises. The course also provides training on public outreach, based on CSAV's Hawaii-specific hazards outreach programs, and volcano preparedness and interactions with the media during volcanic crises. It is an intensive eight week course with instruction and field activities underway 6 days per week; it is now offered in two locations, Hawaii Island, for six weeks, and the Cascades volcanoes of the Pacific Northwest, for two weeks, to enable trainees to experience field conditions in both basaltic and continental volcanic environments. The survival of the program for more than two decades demonstrates that a need for such training exists and there has been interaction and contribution to the program by the research community, however broader engagement with the latter continues to present challenges. Some of the reasons for this will be discussed.

  20. Thermal surveillance of active volcanoes. [infrared scanner recordings of thermal anomalies of Mt. Baker volcano

    Science.gov (United States)

    Friedman, J. D. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. By the end of 1973, aerial infrared scanner traverses for thermal anomaly recordings of all Cascade Range volcanoes were essentially completed. Amplitude level slices of the Mount Baker anomalies were completed and compiled at a scale of 1:24,000, thus producing, for the first time, an accurate map of the distribution and intensity of thermal activity on Mount Baker. The major thermal activity is concentrated within the crater south of the main summit and although it is characterized by intensive solfataric activity and warm ground, it is largely subglacial, causing the development of sizable glacier perforation features. The outgoing radiative flux from the east breach anomalies is sufficient to account for the volume of ice melted to form the glacier perforations. DCP station 6251 has been monitoring a thermally anomalous area on the north slope of Mount Baker. The present thermal activity of Mount Baker accounts for continuing hydrothermal alteration in the crater south of the main summit and recurrent debris avalanches from Sherman Peak on its south rim. The infrared anomalies mapped as part of the experiment SR 251 are considered the basic evidence of the subglacial heating which was the probable triggering mechanism of an avalanche down Boulder Glacier on August 20-21, 1973.

  1. 2014 volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

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

    2017-09-07

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

  2. Vertical Motions of Oceanic Volcanoes

    Science.gov (United States)

    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

  3. Characteristics and features of the submarine landslides in passive and active margin southwestern offshore Taiwan

    Science.gov (United States)

    Yeh, Y. C.

    2016-12-01

    In the past decade, numerous multi-channel seismic surveys as well as near seafloor high resolution geophysical investigations were conducted in order to explore and estimate the reserves of gas hydrate southwestern offshore Taiwan. The previous object was focused on searching substitute energy (i.e. gas hydrate) rather than geo-hazards. However, it is suggested that most of the gas hydrate is generally distributed at slope area southwestern offshore Taiwan, which indicates the slope may be failed when steady state was disturbed by some factors, such as sea level or climate change. In addition, once gas hydrate was dissociated, this may induce submarine landslide that further cause devastated tsunami. Thus, it is of great urgency to investigate potential landslide area, particularly, the hydrate-rich continental slope (active and passive margins) in adjacent to populous city like Kaohsiung. In this study, we collected several high resolution multi-channel seismic data with ten seconds shooting rate and 3.125 meters group interval streamer by using R/V ORI and R/V ORV. The seismic data were processed in conventional data processing strategy: bad trace clean, geometry settings, band-pass filter, de-convolution, surface-related multiple rejection, radon filter, stacking,kirchhoff migration and time to depth conversion. Combine the results obtained from the MCS data and subbottom profiles, two major results could be raised in the active margin as followed: (1) Most of the surface creeping and landslide was occurred shallower than 500 meters in water depth, which should be related to the inter-bedded fluid activities. (2) The landslide distribution is lagly affected by the presence of diaper, suggesting the subsequent mud diapirism may destruct slope stability; (3) The submarine landslide deeper than 800 meters in water depth distributes in the thrust fold area, that is probably referred to active thrusting. In the passive margin, large volume mass transportation

  4. Linking subsurface to surface degassing at active volcanoes: A thermodynamic model with applications to Erebus volcano

    Science.gov (United States)

    Iacovino, Kayla

    2015-12-01

    Volcanic plumbing systems are the pathways through which volatiles are exchanged between the deep Earth and the atmosphere. The interplay of a multitude of processes occurring at various depths in the system dictates the composition and quantity of gas eventually erupted through volcanic vents. Here, a model is presented as a framework for interpreting surface volcanic gas measurements in terms of subsurface degassing processes occurring throughout a volcanic plumbing system. The model considers all possible sources of fluid from multiple depths, including degassing of dissolved volatiles during crystallization and/or decompression as recorded in melt inclusions plus any co-existing fluid phase present in a magma reservoir. The former is achieved by differencing melt inclusion volatile contents between groups of melt inclusions saturated at discrete depths. The latter is calculated using a thermodynamic model, which computes the composition of a C-O-H-S fluid in equilibrium with a melt given a minimum of five thermodynamic parameters commonly known for natural systems (T, P, fO2, either fH2 or one parameter for H2O, and either fS2 or one parameter for CO2). The calculated fluids are thermodynamically decompressed and run through a mixing model, which finds all possible mixtures of subsurface fluid that match the chemistry of surface gas within ±2.0 mol%. The method is applied to Mount Erebus (Antarctica), an active, intraplate volcano whose gas emissions, which emanate from an active phonolitic lava lake, have been well quantified by FTIR, UV spectroscopy, and multi-gas sensors over the last several decades. In addition, a well-characterized suite of lavas and melt inclusions, and petrological interpretations thereof, represent a wealth of knowledge about the shallow, intermediate, and deep parts of the Erebus plumbing system. The model has been used to calculate the compositions of seven C-O-H-S fluids that originate from four distinct regions within the Erebus

  5. Tectonic activity and the evolution of submarine canyons: The Cook Strait Canyon system, New Zealand

    Science.gov (United States)

    Micallef, Aaron; Mountjoy, Joshu; Barnes, Philip; Canals, Miquel; Lastras, Galderic

    2016-04-01

    Submarine canyons are Earth's most dramatic erosional features, comprising steep-walled valleys that originate in the continental shelf and slope. They play a key role in the evolution of continental margins by transferring sediments into deep water settings and are considered important biodiversity hotspots, pathways for nutrients and pollutants, and analogues of hydrocarbon reservoirs. Although comprising only one third of continental margins worldwide, active margins host more than half of global submarine canyons. We still lack of thorough understanding of the coupling between active tectonics and submarine canyon processes, which is necessary to improve the modelling of canyon evolution in active margins and derive tectonic information from canyon morphology. The objectives of this study are to: (i) understand how tectonic activity influences submarine canyon morphology, processes, and evolution in an active margin, and (2) formulate a generalised model of canyon development in response to tectonic forcing based on morphometric parameters. We fulfil these objectives by analysing high resolution geophysical data and imagery from Cook Strait Canyon system, offshore New Zealand. Using these data, we demonstrate that tectonic activity, in the form of major faults and structurally-generated tectonic ridges, leaves a clear topographic signature on submarine canyon location and morphology, in particular their dendritic and sinuous planform shapes, steep and linear longitudinal profiles, and cross-sectional asymmetry and width. We also report breaks/changes in canyon longitudinal slope gradient, relief and slope-area regression models at the intersection with faults. Tectonic activity gives rise to two types of knickpoints in the Cook Strait Canyon. The first type consists of low slope gradient, rounded and diffusive knickpoints forming as a result of short wavelength folds or fault break outs and being restored to an equilibrium profile by upstream erosion and

  6. Submarine earthquake rupture, active faulting and volcanism along the major Liquiñe-Ofqui Fault Zone and implications for seismic hazard assessment in the Patagonian Andes Ruptura sísmica submarina, tectónica y volcanismo activo a lo largo de la Falla Liquiñe-Ofqui e implicancias para el peligro sísmico en los Andes patagónicos

    OpenAIRE

    Gabriel Vargas; Sofía Rebolledo; Sergio A Sepúlveda; Alfredo Lahsen; Ricardo Thiele; Brian Townley; Cristóbal Padilla; Rodrigo Rauld; Maria José Herrera; Marisol Lara

    2013-01-01

    The Liquiñe-Ofqui fault zone (LOFZ) in the Patagonian Andes is an active major transpressional intra-arc fault system along which Quaternary faulting and volcanism develop. Subaerial and submarine geomorphologic and structural characterization of latest Pleistocene-Holocene faults and monogenetic volcanoes allows us to assess geological cartography of active faults and the kinematic model for recent tectonics during postglacial times, since 12,000 cal. years BP. This allows increasing the bas...

  7. Evidence from acoustic imaging for submarine volcanic activity in 2012 off the west coast of El Hierro (Canary Islands, Spain)

    Science.gov (United States)

    Pérez, Nemesio M.; Somoza, Luis; Hernández, Pedro A.; de Vallejo, Luis González; León, Ricardo; Sagiya, Takeshi; Biain, Ander; González, Francisco J.; Medialdea, Teresa; Barrancos, José; Ibáñez, Jesús; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

    2014-12-01

    We report precursory geophysical, geodetic, and geochemical signatures of a new submarine volcanic activity observed off the western coast of El Hierro, Canary Islands. Submarine manifestation of this activity has been revealed through acoustic imaging of submarine plumes detected on the 20-kHz chirp parasound subbottom profiler (TOPAS PS18) mounted aboard the Spanish RV Hespérides on June 28, 2012. Five distinct "filament-shaped" acoustic plumes emanating from the flanks of mounds have been recognized at water depth between 64 and 88 m on a submarine platform located NW El Hierro. These plumes were well imaged on TOPAS profiles as "flares" of high acoustic contrast of impedance within the water column. Moreover, visible plumes composed of white rafts floating on the sea surface and sourcing from the location of the submarine plumes were reported by aerial photographs on July 3, 2012, 5 days after acoustic plumes were recorded. In addition, several geophysical and geochemical data support the fact that these submarine vents were preceded by several precursory signatures: (i) a sharp increase of the seismic energy release and the number of daily earthquakes of magnitude ≥2.5 on June 25, 2012, (ii) significant vertical and horizontal displacements observed at the Canary Islands GPS network (Nagoya University-ITER-GRAFCAN) with uplifts up to 3 cm from June 25 to 26, 2012, (iii) an anomalous increase of the soil gas radon activity, from the end of April until the beginning of June reaching peak values of 2.7 kBq/m3 on June 3, 2012, and (iv) observed positive peak in the air-corrected value of 3He/4He ratio monitored in ground waters (8.5 atmospheric 3He/4He ratio ( R A)) at the northwestern El Hierro on June 16, 2012. Combining these submarine and subaerial information, we suggest these plumes are the consequence of submarine vents exhaling volcanic gas mixed with fine ash as consequence of an event of rapid rise of volatile-rich magma beneath the NW submarine ridge

  8. Late Holocene phases of dome growth and Plinian activity at Guagua Pichincha volcano (Ecuador)

    NARCIS (Netherlands)

    Robin, Claude; Samaniego, Pablo; Le Pennec, Jean-Luc; Mothes, Patricia; van der Plicht, Johannes

    2008-01-01

    Since the eruption which affected Quito in AD 1660, Guagua Pichincha has been considered a hazardous volcano. Based on field studies and twenty C-14 dates, this paper discusses the eruptive activity of this volcano, especially that of the last 2000 years. Three major Plinian eruptions with

  9. Evaluation of Llaima volcano activities for localization and classification of LP, VT and TR events

    Science.gov (United States)

    Dehghan Firoozabadi, Ali; Seguel, Fabian; Soto, Ismael; Guevara, David; Huenupan, Fernando; Curilem, Millaray; Franco, Luis

    2017-09-01

    Evaluation of seismic signals is one of the most important research topics on Volcanology. Volcanoes have daily activity; therefore, high speed evaluation of recorded signals is a challenge for improving the study of the natural phenomena occurring inside these natural formations. The aim of this paper is the evaluation (denoising, localization and classification) and analysis of Llaima volcano activities, one of the most actives volcanoes in South America. Different already proposed methods, such as, Butterworth, Spectral Subtraction (SS) and Wiener Filter (WF) are compared to the proposed Modified Spectral Subtraction (MSS) and Modified Wiener Filter (MWF) to find the best method for denoising the volcano signals. Then, event localization based on received signals of volcano is performed. In this step, Time Delay Estimation (TDE)-based method is used on data acquired from 3 mechanical sensors located in the volcano area. The proposed method is used to estimate the area for event location. The proposed denoising methods make the starting point for the event more evident to increase the localization accuracy for events where the starting point is difficult to find. In the last step, a method based on the novel DNN technique is proposed to classify the three main events occurring in the Llaima volcano (TR (Tremor), LP (Long Period) and VT (Volcano Tectonic)).

  10. Trace element distribution, with a focus on gold, in copper-rich and zinc-rich sulfide chimneys from Brothers submarine volcano, Kermadec arc

    Science.gov (United States)

    Berkenbosch, H. A.; de Ronde, C. E.; McNeill, A.; Goemann, K.; Gemmell, J. B.

    2012-12-01

    Brothers volcano is a dacitic volcano located along the Kermadec arc, New Zealand, and hosts the NW Caldera hydrothermal vent field perched on part of the steep caldera walls. The field strikes for ~600 m between depths of 1550 and 1700 m and includes numerous, active, high-temperature (max 302°C) chimneys and even more dead, sulfide-rich spires. Chimney samples collected from Brothers show distinct mineralogical zonation reflecting gradients in oxidation state, temperature, and pH from the inner walls in contact with hydrothermal fluids through to the outer walls in contact with seawater. Minerals deposited from hotter fluids (e.g., chalcopyrite) are located in the interior of the chimneys and are surrounded by an external zone of minerals deposited by cooler fluids (e.g., sulfates, sphalerite). Four chimneys types are identified at Brothers volcano based on the relative proportions of chalcopyrite and sulfate layers, and the presence or absence of anhydrite. Two are Cu-rich, i.e., chalcopyrite-rich and chalcopyrite-bornite-rich chimneys, and two are Zn-rich, i.e., sphalerite-rich and sphalerite-chalcopyrite-rich. Barite and anhydrite are common to both Cu-rich chimney types whereas Zn-rich chimneys contain barite only. The main mineral phases in all the chimneys are anhydrite, barite, chalcopyrite, pyrite/marcasite, and sphalerite. Trace minerals include galena, covellite, tennantite, realgar, chalcocite, bornite, hematite, goethite, Pb-As sulfosalts, and Bi- or Au-tellurides. The vast majority of tellurides are <5 μm in size and they commonly form in bands, cluster in patches, or occur along internal grain boundaries within chalcopyrite. In sulfate layers adjacent to the chalcopyrite zones tellurides can occur as inclusions in anhydrite, barite or pyrite and/or occupy void space within the chimney. The occurrence of specular hematite and Bi- or Au-tellurides associated with chalcopyrite are consistent with magmatic contributions to the NW Caldera vent site

  11. Embedded ARM system for volcano monitoring in remote areas: application to the active volcano on Deception Island (Antarctica).

    Science.gov (United States)

    Peci, Luis Miguel; Berrocoso, Manuel; Fernández-Ros, Alberto; García, Alicia; Marrero, José Manuel; Ortiz, Ramón

    2014-01-02

    This paper describes the development of a multi-parameter system for monitoring volcanic activity. The system permits the remote access and the connection of several modules in a network. An embedded ARM™ processor has been used, allowing a great flexibility in hardware configuration. The use of a complete Linux solution (Debian™) as Operating System permits a quick, easy application development to control sensors and communications. This provides all the capabilities required and great stability with relatively low energy consumption. The cost of the components and applications development is low since they are widely used in different fields. Sensors and commercial modules have been combined with other self-developed modules. The Modular Volcano Monitoring System (MVMS) described has been deployed on the active Deception Island (Antarctica) volcano, within the Spanish Antarctic Program, and has proved successful for monitoring the volcano, with proven reliability and efficient operation under extreme conditions. In another context, i.e., the recent volcanic activity on El Hierro Island (Canary Islands) in 2011, this technology has been used for the seismic equipment and GPS systems deployed, thus showing its efficiency in the monitoring of a volcanic crisis.

  12. Embedded ARM System for Volcano Monitoring in Remote Areas: Application to the Active Volcano on Deception Island (Antarctica

    Directory of Open Access Journals (Sweden)

    Luis Miguel Peci

    2014-01-01

    Full Text Available This paper describes the development of a multi-parameter system for monitoring volcanic activity. The system permits the remote access and the connection of several modules in a network. An embedded ARMTM processor has been used, allowing a great flexibility in hardware configuration. The use of a complete Linux solution (DebianTM as Operating System permits a quick, easy application development to control sensors and communications. This provides all the capabilities required and great stability with relatively low energy consumption. The cost of the components and applications development is low since they are widely used in different fields. Sensors and commercial modules have been combined with other self-developed modules. The Modular Volcano Monitoring System (MVMS described has been deployed on the active Deception Island (Antarctica volcano, within the Spanish Antarctic Program, and has proved successful for monitoring the volcano, with proven reliability and efficient operation under extreme conditions. In another context, i.e., the recent volcanic activity on El Hierro Island (Canary Islands in 2011, this technology has been used for the seismic equipment and GPS systems deployed, thus showing its efficiency in the monitoring of a volcanic crisis.

  13. A dynamical analysis of the seismic activity of Villarrica volcano (Chile) during September-October 2000

    Energy Technology Data Exchange (ETDEWEB)

    Tarraga, Marta [Departamento de Volcanologia. Museo Nacional de Ciencias Naturales, CSIC, Madrid (Spain)], E-mail: martat@mncn.csic.es; Carniel, Roberto [Dipartimento di Georisorse e Territorio, Universita di Udine, Via Cotonificio 114, 33100 Udine (Italy)], E-mail: roberto.carniel@uniud.it; Ortiz, Ramon; Garcia, Alicia [Departamento de Volcanologia. Museo Nacional de Ciencias Naturales, CSIC, Madrid (Spain); Moreno, Hugo [Observatorio Volcanologico de los Andes del Sur (OVDAS), Servicio Nacional de Geologia y Mineria de Chile (SERNAGEOMIN), Temuco, IX Region (Chile)

    2008-09-15

    Although Villarrica volcano in Chile is one of the most active in the southern Andes, the literature studying its seismic activity is relatively scarce. An interesting problem recently tackled is the possibility for a regional tectonic event to trigger a change in the volcanic activity of this basaltic to basaltic-andesitic volcano, which is in turn reflected in the time evolution of the properly volcanic seismicity, especially in the form of a continuous volcanic tremor. In this work, we conduct a spectral, dynamical and statistical analysis of the tremor recorded during September and October 2000, in order to characterize the anomalous behaviour of the volcano following a tectonic event recorded on 20th September 2000. The observed dynamical transitions are compared with remote sensing and visual observations describing the changes in the eruptive style of the volcano.

  14. TOMO-ETNA experiment at Etna volcano: activities on land

    Directory of Open Access Journals (Sweden)

    Jesús M. Ibáñez

    2016-09-01

    Full Text Available In the present paper we describe the on-land field operations integrated in the TOMO-ETNA experiment carried out in June-November 2014 at Mt. Etna volcano and surrounding areas. This terrestrial campaign consists in the deployment of 90 short-period portable three-component seismic stations, 17 Broadband seismometers and the coordination with 133 permanent seismic station belonging to Italy’s Istituto Nazionale di Geofisica e Vulcanologia (INGV. This temporary seismic network recorded active and passive seismic sources. Active seismic sources were generated by an array of air-guns mounted in the Spanish oceanographic vessel “Sarmiento de Gamboa” with a power capacity of up to 5200 cubic inches. In total more than 26,000 shots were fired and more than 450 local and regional earthquakes were recorded. We describe the whole technical procedure followed to guarantee the success of this complex seismic experiment. We started with the description of the location of the potential safety places to deploy the portable network and the products derived from this search (a large document including full characterization of the sites, owners and indication of how to arrive to them. A full technical description of the seismometers and seismic sources is presented. We show how the portable seismic network was deployed, maintained and recovered in different stages. The large international collaboration of this experiment is reflected in the participation of more than 75 researchers, technicians and students from different institutions and countries in the on-land activities. The main objectives of the experiment were achieved with great success.

  15. Submarine silicic volcanism: Processes and products

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.

    The occurrence of submarine silicic volcanics is rare at the mid-oceanic ridges, abyssal depths, seamounts and fracture zones. Hydrothermal processes are active in submarine silicic environments and are associated with host ores of Cu, Au, Ag, Pb...

  16. Subaqueous cryptodome eruption, hydrothermal activity and related seafloor morphologies on the andesitic North Su volcano

    Science.gov (United States)

    Thal, Janis; Tivey, Maurice; Yoerger, Dana R.; Bach, Wolfgang

    2016-09-01

    North Su is a double-peaked active andesite submarine volcano located in the eastern Manus Basin of the Bismarck Sea that reaches a depth of 1154 m. It hosts a vigorous and varied hydrothermal system with black and white smoker vents along with several areas of diffuse venting and deposits of native sulfur. Geologic mapping based on ROV observations from 2006 and 2011 combined with morphologic features identified from repeated bathymetric surveys in 2002 and 2011 documents the emplacement of a volcanic cryptodome between 2006 and 2011. We use our observations and rock analyses to interpret an eruption scenario where highly viscous, crystal-rich andesitic magma erupted slowly into the water-saturated, gravel-dominated slope of North Su. An intense fragmentation process produced abundant blocky clasts of a heterogeneous magma (olivine crystals within a rhyolitic groundmass) that only rarely breached through the clastic cover onto the seafloor. Phreatic and phreatomagmatic explosions beneath the seafloor cause mixing of juvenile and pre-existing lithic clasts and produce a volcaniclastic deposit. This volcaniclastic deposit consists of blocky, non-altered clasts next, variably (1-100%) altered clasts, hydrothermal precipitates and crystal fragments. The usually applied parameters to identify juvenile subaqueous lava fragments, i.e. fluidal shape or chilled margin, were not applicable to distinguish between pre-existing non-altered clasts and juvenile clasts. This deposit is updomed during further injection of magma and mechanical disruption. Gas-propelled turbulent clast-recycling causes clasts to develop variably rounded shapes. An abundance of blocky clasts and the lack of clasts typical for the contact of liquid lava with water is interpreted to be the result of a cooled, high-viscosity, crystal-rich magma that failed as a brittle solid upon stress. The high viscosity allows the lava to form blocky and short lobes. The pervasive volcaniclastic cover on North Su is

  17. Morphology of Bezymianny Volcano and evidence of its activity in 1949 before the 1956 catastrophic eruption

    Science.gov (United States)

    Shevchenko, Alina; Dvigalo, Viktor

    2017-04-01

    On March 30, 1956, the Bezymianny Volcano eruption was one of the greatest volcanic events of the 20th century, not only in the Kamchatka Peninsula, but in the whole world. The subsequent intensive lava dome growth and lava flow effusion lead us to consider this volcano as one of the most active in Kamchatka during recent times. Studies of Bezymianny Volcano before the eruption are very poor. It was thought to be dormant for 1000 years. Previously, pre-eruptive morphology of the volcano was reconstructed on the basis of very poor initial data — a 1:100000 scale map from 1950 with low detalization of relief, and some ground-based single photographs. Photogrammetric processing of archival 1949 stereo aerial photographs allowed us to reconstruct the morphology and state of Bezymianny Volcano prior to the 1956 catastrophic eruption, build DTM, and define quantitative characteristics of its morphological elements. The volcano was about 1500 m in height (3084 m above sea level). It was bisected by two collapse scars directed toward the west and east from the summit. Dimensions of the eastern scar reached 1900×630 m, and its depth was up to 50 m. Dimensions of the western scar were 1050×380 m, and its depth was up to 70 m. The summit had an explosion crater 350 m in diameter with an inner cinder cone 100 m in height. A small horseshoe-shaped crater 35 m in diameter and 5 m in depth was located at the top of the cone. Multiple lava flows of different size and morphology covered the edifice of the volcano. Their lengths varied from 200 m to 3500 m. Furthermore, the 1949 photographs show that the volcano was not dormant as was thought previously. In these, we discovered evidence of recent activity. The summit crater, the cinder cone with talus, and the lava flows are poorly eroded. On the north-eastern flank, we can see thin deposits of pyroclastic flows up to 280 m in length that would have been washed away during the course of 1000 years of dormancy. Also, there are

  18. Addressing submarine geohazards through scientific drilling

    Science.gov (United States)

    Camerlenghi, A.

    2009-04-01

    Natural submarine geohazards (earthquakes, volcanic eruptions, landslides, volcanic island flank collapses) are geological phenomena originating at or below the seafloor leading to a situation of risk for off-shore and on-shore structures and the coastal population. Addressing submarine geohazards means understanding their spatial and temporal variability, the pre-conditioning factors, their triggers, and the physical processes that control their evolution. Such scientific endeavour is nowadays considered by a large sector of the international scientific community as an obligation in order to contribute to the mitigation of the potentially destructive societal effects of submarine geohazards. The study of submarine geohazards requires a multi-disciplinary scientific approach: geohazards must be studied through their geological record; active processes must be monitored; geohazard evolution must be modelled. Ultimately, the information must be used for the assessment of vulnerability, risk analysis, and development of mitigation strategies. In contrast with the terrestrial environment, the oceanic environment is rather hostile to widespread and fast application of high-resolution remote sensing techniques, accessibility for visual inspection, sampling and installation of monitoring stations. Scientific Drilling through the IODP (including the related pre site-survey investigations, sampling, logging and in situ measurements capability, and as a platform for deployment of long term observatories at the surface and down-hole) can be viewed as the centre of gravity of an international, coordinated, multi-disciplinary scientific approach to address submarine geohazards. The IODP Initial Science Plan expiring in 2013 does not address openly geohazards among the program scientific objectives. Hazards are referred to mainly in relation to earthquakes and initiatives towards the understanding of seismogenesis. Notably, the only drilling initiative presently under way is the

  19. Exploring the submarine Graham Bank in the Sicily Channel

    Directory of Open Access Journals (Sweden)

    Mauro Coltelli

    2016-05-01

    Full Text Available In the Sicily Channel, volcanic activity has been concentrated mainly on the Pantelleria and Linosa islands, while minor submarine volcanism took place in the Adventure, Graham and Nameless banks. The volcanic activity spanned mostly during Plio-Pleistocene, however, historical submarine eruptions occurred in 1831 on the Graham Bank and in 1891 offshore Pantelleria Island. On the Graham Bank, 25 miles SW of Sciacca, the 1831 eruption formed the short-lived Ferdinandea Island that represents the only Italian volcano active in historical times currently almost completely unknown and not yet monitored. Moreover, most of the Sicily Channel seismicity is concentrated along a broad NS belt extending from the Graham Bank to Lampedusa Island. In 2012, the Istituto Nazionale di Geofisica e Vulcanologia (INGV carried out a multidisciplinary oceanographic cruise, named “Ferdinandea 2012”, the preliminary results of which represent the aim of this paper. The cruise goal was the mapping of the morpho-structural features of some submarine volcanic centres located in the northwestern side of the Sicily Channel and the temporary recording of their seismic and degassing activity. During the cruise, three OBS/Hs (ocean bottom seismometer with hydrophone were deployed near the Graham, Nerita and Terribile submarine banks. During the following 9 months they have recorded several seismo-acoustic signals produced by both tectonic and volcanic sources. A high-resolution bathymetric survey was achieved on the Graham Bank and on the surrounding submarine volcanic centres. A widespread and voluminous gas bubbles emission was observed by both multibeam sonar echoes and a ROV (remotely operated vehicle along the NW side of the Graham Bank, where gas and seafloor samples were also collected.

  20. Volcano collapse along the Aleutian Ridge (western Aleutian Arc

    Directory of Open Access Journals (Sweden)

    C. Montanaro

    2011-03-01

    Full Text Available The Aleutian Ridge, in the western part of the Aleutian Arc, consists of a chain of volcanic islands perched atop the crest of a submarine ridge with most of the active Quaternary stratocones or caldera-like volcanoes being located on the northern margins of the Aleutian Islands. Integrated analysis of marine and terrestrial data resulted in the identification and characterization of 17 extensive submarine debris avalanche deposits from 11 volcanoes. Two morphological types of deposits are recognizable, elongate and lobate, with primary controls on the size and distribution of the volcanic debris being the volume and nature of material involved, proportion of fine grained material, depth of emplacement and the paleo-bathymetry. Volume calculations show the amount of material deposited in debris avalanches is as much as three times larger than the amount of material initially involved in the collapse, suggesting the incorporation of large amounts of submarine material during transport. The orientation of the collapse events is influenced by regional fault systems underling the volcanoes. The western Aleutian Arc has a significant tsunamigenic potential and communities within the Aleutian Islands and surrounding areas of the North Pacific as well as shipping and fishing fleets that cross the North Pacific may be at risk during future eruptions in this area.

  1. Active volcanoes observed through Art: the contribution offered by the social networks

    Science.gov (United States)

    Neri, Marco; Neri, Emilia

    2015-04-01

    Volcanoes have always fascinated people for the wild beauty of their landscapes and also for the fear that they arouse with their eruptive actions, sometimes simply spectacular, but other times terrifying and catastrophic for human activities. In the past, volcanoes were sometimes imagined as a metaphysical gateway to the otherworld; they have inspired the creation of myths and legends ever since three thousand years ago, also represented by paintings of great artistic impact. Modern technology today offers very sophisticated and readily accessed digital tools, and volcanoes continue to be frequently photographed and highly appreciated natural phenomena. Moreover, in recent years, the spread of social networks (Facebook, Twitter, YouTube, Instagram, etc.) have made the widespread dissemination of graphic contributions even easier. The result is that very active and densely inhabited volcanoes such as Etna, Vesuvius and Aeolian Islands, in Italy, have become among the most photographed subjects in the world, providing a popular science tool with formidable influence and usefulness. The beauty of these landscapes have inspired both professional artists and photographers, as well as amateurs, who compete in the social networks for the publication of the most spectacular, artistic or simply most informative images. The end result of this often frantic popular scientific activity is at least two-fold: on one hand, it provides geoscientists and science communicators a quantity of documentation that is almost impossible to acquire through the normal systems of volcano monitoring, while on the other it raises awareness and respect for the land among the civil community.

  2. Submarine hydrodynamics

    CERN Document Server

    Renilson, Martin

    2015-01-01

    This book adopts a practical approach and presents recent research together with applications in real submarine design and operation. Topics covered include hydrostatics, manoeuvring, resistance and propulsion of submarines. The author briefly reviews basic concepts in ship hydrodynamics and goes on to show how they are applied to submarines, including a look at the use of physical model experiments. The issues associated with manoeuvring in both the horizontal and vertical planes are explained, and readers will discover suggested criteria for stability, along with rudder and hydroplane effectiveness. The book includes a section on appendage design which includes information on sail design, different arrangements of bow planes and alternative stern configurations. Other themes explored in this book include hydro-acoustic performance, the components of resistance and the effect of hull shape. Readers will value the author’s applied experience as well as the empirical expressions that are presented for use a...

  3. Methods of InSAR atmosphere correction for volcano activity monitoring

    Science.gov (United States)

    Gong, W.; Meyer, F.; Webley, P.W.; Lu, Z.

    2011-01-01

    When a Synthetic Aperture Radar (SAR) signal propagates through the atmosphere on its path to and from the sensor, it is inevitably affected by atmospheric effects. In particular, the applicability and accuracy of Interferometric SAR (InSAR) techniques for volcano monitoring is limited by atmospheric path delays. Therefore, atmospheric correction of interferograms is required to improve the performance of InSAR for detecting volcanic activity, especially in order to advance its ability to detect subtle pre-eruptive changes in deformation dynamics. In this paper, we focus on InSAR tropospheric mitigation methods and their performance in volcano deformation monitoring. Our study areas include Okmok volcano and Unimak Island located in the eastern Aleutians, AK. We explore two methods to mitigate atmospheric artifacts, namely the numerical weather model simulation and the atmospheric filtering using Persistent Scatterer processing. We investigate the capability of the proposed methods, and investigate their limitations and advantages when applied to determine volcanic processes. ?? 2011 IEEE.

  4. 2015 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

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

    2017-09-28

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

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

    Science.gov (United States)

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

    2016-04-01

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

  6. Methanogenic activity and diversity in the centre of the Amsterdam Mud Volcano, Eastern Mediterranean Sea.

    Science.gov (United States)

    Lazar, Cassandre Sara; John Parkes, R; Cragg, Barry A; L'Haridon, Stephane; Toffin, Laurent

    2012-07-01

    Marine mud volcanoes are geological structures emitting large amounts of methane from their active centres. The Amsterdam mud volcano (AMV), located in the Anaximander Mountains south of Turkey, is characterized by intense active methane seepage produced in part by methanogens. To date, information about the diversity or the metabolic pathways used by the methanogens in active centres of marine mud volcanoes is limited. (14)C-radiotracer measurements showed that methylamines/methanol, H(2)/CO(2) and acetate were used for methanogenesis in the AMV. Methylotrophic methanogenesis was measured all along the sediment core, Methanosarcinales affiliated sequences were detected using archaeal 16S PCR-DGGE and mcrA gene libraries, and enrichments of methanogens showed the presence of Methanococcoides in the shallow sediment layers. Overall acetoclastic methanogenesis was higher than hydrogenotrophic methanogenesis, which is unusual for cold seep sediments. Interestingly, acetate porewater concentrations were extremely high in the AMV sediments. This might be the result of organic matter cracking in deeper hotter sediment layers. Methane was also produced from hexadecanes. For the most part, the methanogenic community diversity was in accordance with the depth distribution of the H(2)/CO(2) and acetate methanogenesis. These results demonstrate the importance of methanogenic communities in the centres of marine mud volcanoes. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  7. Novel microbial communities of the Haakon Mosby mud volcano and their role as a methane sink.

    Science.gov (United States)

    Niemann, Helge; Lösekann, Tina; de Beer, Dirk; Elvert, Marcus; Nadalig, Thierry; Knittel, Katrin; Amann, Rudolf; Sauter, Eberhard J; Schlüter, Michael; Klages, Michael; Foucher, Jean Paul; Boetius, Antje

    2006-10-19

    Mud volcanism is an important natural source of the greenhouse gas methane to the hydrosphere and atmosphere. Recent investigations show that the number of active submarine mud volcanoes might be much higher than anticipated (for example, see refs 3-5), and that gas emitted from deep-sea seeps might reach the upper mixed ocean. Unfortunately, global methane emission from active submarine mud volcanoes cannot be quantified because their number and gas release are unknown. It is also unclear how efficiently methane-oxidizing microorganisms remove methane. Here we investigate the methane-emitting Haakon Mosby Mud Volcano (HMMV, Barents Sea, 72 degrees N, 14 degrees 44' E; 1,250 m water depth) to provide quantitative estimates of the in situ composition, distribution and activity of methanotrophs in relation to gas emission. The HMMV hosts three key communities: aerobic methanotrophic bacteria (Methylococcales), anaerobic methanotrophic archaea (ANME-2) thriving below siboglinid tubeworms, and a previously undescribed clade of archaea (ANME-3) associated with bacterial mats. We found that the upward flow of sulphate- and oxygen-free mud volcano fluids restricts the availability of these electron acceptors for methane oxidation, and hence the habitat range of methanotrophs. This mechanism limits the capacity of the microbial methane filter at active marine mud volcanoes to <40% of the total flux.

  8. Eruptive history, current activity and risk estimation using geospatial information in the Colima volcano, Mexico

    Science.gov (United States)

    Suarez-Plascencia, C.; Camarena-Garcia, M.; Nunez-Cornu, F. J.; Flores-Peña, S.

    2013-12-01

    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. In January 20, 1913, Colima had its biggest explosion of the twentieth century, with VEI 4, after the volcano had been dormant for almost 40 years. In 1961, a dome reached the northeastern edge of the crater and started a new lava flow, and from this date maintains constant activity. In February 10, 1999, a new explosion 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 altitudes between 4,500 and 9,000 masl, 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 affecting the nearby villages: Tuxpan, Tonila, Zapotlan, Cuauhtemoc, Comala, Zapotitlan de Vadillo and Toliman. During 2005 to July 2013, this volcano has had an intense effusive-explosive activity; similar to the one that took place during the period of 1890 through 1905. That was before the Plinian eruption of 1913, where pyroclastic flows reached a distance of 15 km from the crater. In this paper we estimate the risk of Colima volcano through the analysis of the vulnerability variables, hazard and exposure, for which we use: satellite imagery, recurring Fenix helicopter over flights of the state government of Jalisco, the use of the images of Google Earth and the population census 2010 INEGI. With this information and data identified changes in economic activities, development, and use of land. The expansion of the agricultural frontier in the lower sides of the volcano Colima, and with the advancement of traditional crops of sugar cane and corn, increased the growth of

  9. PBO-Style Seismic and Geodetic Monitoring at Frequently-Active Aleutian Arc Volcanoes

    Science.gov (United States)

    Murray, T. L.; Power, J. A.; Freymueller, J. T.; Tytgat, G.; Moran, S. C.; Lisowski, M.; Johnston, M. J.; Pauk, B. A.; Caplan-Auerbach, J.; Paskievitch, J. F.; Plucinski, T. A.; McNutt, S. R.; Petersen, T.; Mann, D.

    2002-12-01

    A major goal of EarthScope and the Plate Boundary Observatory (PBO) is to obtain real-time data on the dynamics of magma transport and the physical processes surrounding magmatic intrusions before, during, and after eruption. To accomplish this the PBO has selected five active Aleutian arc volcanic centers for instrumentation; Augustine, Pavlof, Unimak Island (the location of Isanotski, Shishaldin, Fisher Caldera, and Westdahl Volcano), Akutan, and Okmok. Six of these volcanoes have erupted within the last 20 years and four are known to be actively deforming. The frequency of eruptive activity at these volcanoes, as well as diverse chemistry of erupted products, makes these volcanic centers unique natural laboratories within the North American plate boundary system for studying active volcanism. During the summer of 2002 the Alaska Volcano Observatory (AVO) began deployment of PBO-style networks consisting of continuous GPS receivers collocated with broadband seismometers at Akutan Volcano and Okmok Caldera. Five GPS receivers were installed in 2002, and are recording on-site. Three GPS receivers on Okmok radio data approximately 70 km to Dutch Harbor. The radio system provides full duplex serial communication between the instruments at each remote site and the central recording system in Dutch Harbor. Planned 2003 work includes adding broadband seismometers to the existing sites and adding three more sites for a total of four telemetered broadband-GPS sites on each volcano. These deployments complement short-period seismic networks that were deployed on Akutan Volcano and Okmok Caldera in 1996 and 2002 and campaign GPS measurements begun in 1996 and 2000, respectively. The instruments installed this year and the addition of the broadband seismometers in 2003 will greatly improve our ability to study volcanic processes. Once the existing networks are enhanced by additional instrumentation through PBO, they will provide the opportunity to study the mechanics and

  10. Virunga Volcanoes Supersite: a collaborative initiative to improve Geohazards Assessment and Monitoring of Active Volcanoes in a highly populated region

    Science.gov (United States)

    Balagizi, Charles M.; Mahinda, Celestin K.; Yalire, Mathieu M.; Ciraba, Honoré M.; Mavonga, Georges T.

    2017-04-01

    Located within the western branch of the East African Rift System (EARS), the Virunga Volcanic Province is a young highly volcanically and seismically active region. It provides a unique opportunity to study deep mantle upwelling through the crust. Several Geohazards are encountered in this highly populated region, and include volcanic hazards (lava flows, volcanic gases and ash, …), earthquake hazard; landslide, mud flows and floods hazards. In addition, the overturn of Lake Kivu (which lies in the Kivu Graben, western branch of the EARS) could release huge CO2 and CH4 into the atmosphere. A few days after the January 17, 2002 Nyiragongo eruption whose lava flows devastated Goma city, destroying the houses of ˜120,000 people, forced a mass self-evacuation of ˜300,000 people of Goma (of estimated ˜400,000 inhabitants), and killed ˜140 people; the international scientific community deployed a "dream scientific team" to evaluate the state of Geohazards in the Virunga region. Particularly, the team had to check whether the stability of Lake Kivu that dissolves ˜300 and ˜60 km3 of CO2 and CH4 (at 0˚ C and 1 atm.) in its deep water was not disturbed due to Nyiragongo lava that entered the lake. Since 2002 several projects were funded with the main goal of accompanying the local scientific team to set up a more professional team to assess and continuous monitor Geohazards in the Virunga. For the time being, while Nyiragongo volcano solely threatens ˜1.5 million inhabitants of Goma (DR Congo) and Gisenyi (Rwanda) cities in addition to people living in the surrounding villages, and Lake Kivu threatening ˜3 million inhabitants of its catchment, the local scientists remain less qualified and equipped. Here we show that collaboration between Virunga local scientists and international scientists through the Geohazards Supersites network could be a most efficient pathway to improve Geohazards assessment and monitoring in the Virunga, and hence yield Disaster Risk

  11. Submarine weathering of silicate minerals and the extent of pore water freshening at active continental margins

    Science.gov (United States)

    Scholz, Florian; Hensen, Christian; Schmidt, Mark; Geersen, Jacob

    2013-01-01

    In order to investigate how submarine weathering processes may affect the water balance of sediments at convergent plate margins, six sediment cores were retrieved off Central Chile at water depth between ˜800 and 4000 m. The sediment solid phase was analyzed for its major element composition and the pore fluids were analyzed for dissolved sulfate, sulfide, total alkalinity, major cations, chloride, bromide, iodide, hydrocarbons as well as the carbon isotopic composition of methane. Because of negligible weathering on land, surface sediments off Central Chile are rich in reactive silicate minerals and have a bulk composition similar to volcanic rocks in the adjacent Andes. Deep-sourced fluxes of alkalinity, cations and chloride indicate that silicate minerals are subject to weathering in the forearc during burial. Comparison of deep-sourced signals with data from nearby Ocean Drilling Program Sites reveals two different types of weathering processes: In shallow (tens of meters), methanic sediments of slope basins with high organic carbon burial rates, reactive silicate minerals undergo incongruent dissolution through reaction with CO2 from methanogenesis. At greater burial depth (hundreds of meters), silicate weathering is dominated by authigenic smectite formation. This process is accompanied by uptake of water into the clay interlayers thus leading to elevated salinities in the surrounding pore water. Deep-seated smectite formation is more widespread than shallow silicate dissolution, as it is independent from the availability of CO2 from methanogenesis. Although solute transport is not focused enough to form cold seeps in the proper sense, tectonically induced, diffuse fluid flow transfers the deep-seated signal of smectite formation into the shallow sediments. The temperature-controlled conversion of smectite to illite is considered the most important dehydration process in marine forearc environments (depth of kilometers). However, in agreement with other

  12. Volcanic tremor associated with eruptive activity at Bromo volcano

    Directory of Open Access Journals (Sweden)

    E. Gottschämmer

    1999-06-01

    Full Text Available Three broadband stations were deployed on Bromo volcano, Indonesia, from September to December 1995. The analysis of the seismograms shows that the signals produced by the volcanic sources cover the frequency range from at least 25 Hz down to periods of several minutes and underlines, therefore, the importance of broadband recordings. Frequency analysis reveals that the signal can be divided into four domains. In the traditional frequency range of volcanic tremor (1-10 Hz sharp transitions between two distinct values of the tremor amplitude can be observed. Additional tremor signal including frequencies from 10 to 20 Hz could be found during late November and early December. Throughout the whole experiment signals with periods of some hundred seconds were observed which are interpreted as ground tilts. For these long-period signals a particle motion analysis was performed in order to estimate the source location. Depth and radius can be estimated when the source is modeled as a sudden pressure change in a sphere. The fourth frequency range lies between 0.1 and 1 Hz and is dominated by two spectral peaks which are due to marine microseism. The phase velocity and the direction of wave propagation of these signals could be determined using the tripartite-method.

  13. Active Volcanoes of the Kurile Islands: A Reference Guide for Aviation Users

    Science.gov (United States)

    Neal, Christina A.; Rybin, Alexander; Chibisova, Marina; Miller, Edward

    2008-01-01

    Introduction: The many volcanoes of the remote and mostly uninhabited Kurile Island arc (fig. 1; table 1) pose a serious hazard for air traffic in the North Pacific. Ash clouds from Kurile eruptions can impact some of the busiest air travel routes in the world and drift quickly into airspace managed by three countries: Russia, Japan, and the United States. Prevailing westerly winds throughout the region will most commonly send ash from any Kurile eruption directly across the parallel North Pacific airways between North America and Asia (Kristine A. Nelson, National Weather Service, oral commun., 2006; fig. 1). This report presents maps showing locations of the 36 most active Kurile volcanoes plotted on Operational Navigational Charts published by the Defense Mapping Agency (map sheets ONC F-10, F-11, and E-10; figs. 1, 2, 3, 4). These maps are intended to assist aviation and other users in the identification of restless Kurile volcanoes. A regional map is followed by three subsections of the Kurile volcanic arc (North, Central, South). Volcanoes and selected primary geographic features are labeled. All maps contain schematic versions of the principal air routes and selected air navigational fixes in this region.

  14. Study on the medieval eruptive activity of the Somma-Vesuvius volcano in the SW sector

    OpenAIRE

    Paolillo, Annarita

    2016-01-01

    The PhD project is divided in three parts: (i) a detailed mapping of the Southern-Western sector of the Vesuvius, integrating stratigraphic and petrologic data with archaeological and historical information; (ii) a study of the medieval eruptive activity of the Somma-Vesuvius volcano, an important period of the Vesuvius’ activity, which has been definitely under-researched, in which we focused on the correlations between inland and offshore tephra fallout deposits, integrating newly collected...

  15. How volcano monitoring in New Zealand can contribute to a global volcano dataset: The GeoNet Project

    Science.gov (United States)

    Jolly, G. E.; Scott, B.

    2009-12-01

    Volcanism plays an important role in New Zealand. Much of the landscape of the central North Island owes its shape to volcanism, with the soils supporting forestry and farming economies, geothermal systems providing renewable electricity production and the spectacular landscape supporting tourism and adventure. However volcanism also has it disadvantages: eruptive activity brings physical damage and economic losses and, sometimes, tragically the loss of life. Historically, in New Zealand, volcanoes represent the largest single source of fatalities from natural disasters. To better mitigate the hazard from New Zealand’s volcanoes, a multidisciplinary approach is applied. In 2001 the NZ Earthquake Commission (EQC) commenced funding the GeoNet project, providing the first totally national modern geological hazard monitoring system in New Zealand. The GeoNet project is responsibly for monitoring and assessing all of the active volcanoes (and other geological hazards) in New Zealand. The volcano monitoring programme is integrated into the national seismograph and geodetic networks. The volcano monitoring covers active volcanic cones, resting calderas, volcanic fields, and submarine volcanoes. Monitoring techniques include volcano seismology, geodesy, gas and water chemistry, remote sensing and other geophysical techniques, producing a wide variety of data sets, with both temporal and spatial distribution. These data sets form the basis for detailed research to achieve in depth understanding of these volcanoes and will contribute to the global knowledge of volcanic processes. However to achieve this the data sets need to be accessible by a range of end users, so that they can be used to underpin fundamental research and applied hazard assessments. This presentation will outline the NZ data sets and the problems of presenting and sharing them globally.

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

    Science.gov (United States)

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

    2016-02-19

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

  17. Axial seamount: An active ridge axis volcano on the Central Juan De Fuca Ridge

    Science.gov (United States)

    Johnson, H. Paul; Embley, Robert W.

    1990-08-01

    Axial Seamount (some of the manuscripts in this special section refer to the edifice with the more precise name of "Axial Volcano"), a large ridge axis volcano, is located on the central segment of the Juan de Fuca Ridge approximately 250 nautical miles west of the Washington/Oregon/British Columbia coast. Currently both volcanically and hydrothermally active, Axial lies directly at the intersection of the Cobb-Eickelberg Seamount Chain and the Juan de Fuca Ridge (Figure 1). The volcanic activity associated with the seamount formation strongly interacts with, and is affected by, the normal seafloor spreading processes at the intersection. Because of this unique geologic setting, its proximity to west coast ports and oceanographie institutions, and its shallow depth, Axial has become the focus of a large number of scientific investigations over the past decade.

  18. Cellular immune responses and phagocytic activity of fishes exposed to pollution of volcano mud.

    Science.gov (United States)

    Risjani, Yenny; Yunianta; Couteau, Jerome; Minier, Christophe

    2014-05-01

    Since May 29, 2006, a mud volcano in the Brantas Delta of the Sidoarjo district has emitted mud that has inundated nearby villages. Pollution in this area has been implicated in detrimental effects on fish health. In fishes, leukocyte and phagocytic cells play a vital role in body defenses. We report for the first time the effect of "LUSI" volcano mud on the immune systems of fish in the Brantas Delta. The aim of this study was to find biomarkers to allow the evaluation of the effects of volcanic mud and anthropogenic pollution on fish health in the Brantas Delta. The study took places at the Brantas Delta, which was polluted by volcano mud, and at reference sites in Karangkates and Pasuruan. Leukocyte numbers were determined using a Neubauer hemocytometer and a light microscope. Differential leukocyte counts were determined using blood smears stained with May Grunwald-Giemsa, providing neutrophil, lymphocyte and monocyte counts. Macrophages were taken from fish kidney, and their phagocytic activity was measured. In vitro analyses revealed that leukocyte and differential leukocyte counts (DLC) were higher in Channa striata and Chanos chanos caught from the polluted area. Macrophage numbers were higher in Oreochromis mossambicus than in the other species, indicating that this species is more sensitive to pollution. In areas close to volcanic mud eruption, all specimens had lower phagocytic activity. Our results show that immune cells were changed and phagocytic activity was reduced in the polluted area indicating cytotoxicity and alteration of the innate immune system in fishes exposed to LUSI volcano mud and anthropogenic pollution. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. A First: Detailed Tracking of an Erupting Undersea Volcano and its Impacts on the Overlying Ocean via a Submarine Electro-Optical Sensor Network.

    Science.gov (United States)

    Delaney, J. R.

    2016-02-01

    The scientifically diverse and technologically advanced cabled array component of the NSF's Ocean Observatories Initiative consists of 900 km of electro-optical fiber deployed from Pacific City, OR, across active portions of the Juan de Fuca (JdF) tectonic plate, and upward into the overlying ocean. This array, completed in 2014 on time and under budget, enables real-time, high-bandwidth, 2-way communication with seafloor and water column sensor arrays across: 1. the Cascadia accretionary prism, 2. the JdF spreading center, and, 3. portions of the overlying NE Pacific. Oceanographic processes in coastal waters, the California Current, and up to 400 km offshore, are captured by six remote-controlled, profiling moorings covering full-ocean depths. Currently, 6 primary nodes, 17 junction boxes, and 85% of 150 instruments are transmitting data ashore to the Internet via the Pacific NW Gigapop (http://www.pnwgp.net/). All data are archived at the U. of Washington, pending completion of the OOI CyberInfrastructure in October 2015. In 2014, community requests to access data to assess inflation at Axial Seamount, resulted in NSF releasing real-time data from 7 seismometers and 3 pressure sensors (IRIS: http://www.iris.edu/hq/). On April 20-22, 90 participants, met in Seattle to explore scientific responses to an eruption (http://novae.ocean.washington.edu). On April 24, Axial did erupt; seismic events rose dramatically to many hundreds/hour the Axial caldera floor dropped 2.4 m in 16 hours and water temperatures rose by 0.7°C, then declined in 3 weeks to normal values. Water-borne acoustic signals indicated seafloor activity along the rift zone north of Axial. Water column observations also indicated that a large plume of hydrothermal fluid was released during the eruptions. Follow-on field programs documented a 127 m thick lava flow on the northern rift, and a thin eruption within the caldera. These events signal a new era in Ocean Sciences as instantaneous Internet

  20. On the use of earthquake multiplets to study fractures and the temporal evolution of an active volcano

    Directory of Open Access Journals (Sweden)

    O. Coutant

    1996-06-01

    Full Text Available Multiplets, i.e. events with similar waveforms, are common features on active volcanoes. The seismograms of multiplets are analyzed by cross-spectrum techniques: this procedure improves by a factor of about 10 the precision of differential P-arrival times and therefore the accuracy of the relative location of earthquakes. Long period events which cannot be located because of the impossibility to pick up P-waves on individual seismograms can be located with a precision of about 10 m. Such a precision permits fault planes to be mapped inside a volcanic edifice and the azimuth and strike of fractures to be defined. Seismograms of the two events (of a doublet that occur on different dates are analyzed by the Cross Spectrum Moving Window technique (CSMW for measuring the time delay between waves in the coda. The pattern of the delays in the coda is a function of the temporal changes of seismic velocity that occurred inside the volcano during the time interval that separates the two events of a doublet. We illustrate the potential of the doublet technique for detecting temporal changes inside a volcano by performing computations of synthetic seismograms. The case of a dyke injected inside the volcano is considered as well as that of the replenishment of a superficial magma chamber and of a general increase in velocity in the summit of the volcano. Data from Merapi volcano (Indonesiaillustrate a possible temporal velocity change inside the volcano several months before the 1992 eruption.

  1. Estimating eruption temperature from thermal emission spectra of lava fountain activity in the Erta'Ale (Ethiopia) volcano lava lake: Implications for observing Io's volcanoes

    Science.gov (United States)

    Davies, Ashley G.; Keszthelyi, Laszlo P.; McEwen, Alfred S.

    2011-01-01

    We have analysed high-spatial-resolution and high-temporal-resolution temperature measurements of the active lava lake at Erta'Ale volcano, Ethiopia, to derive requirements for measuring eruption temperatures at Io's volcanoes. Lava lakes are particularly attractive targets because they are persistent in activity and large, often with ongoing lava fountain activity that exposes lava at near-eruption temperature. Using infrared thermography, we find that extracting useful temperature estimates from remote-sensing data requires (a) high spatial resolution to isolate lava fountains from adjacent cooler lava and (b) rapid acquisition of multi-color data. Because existing spacecraft data of Io's volcanoes do not meet these criteria, it is particularly important to design future instruments so that they will be able to collect such data. Near-simultaneous data at more than two relatively short wavelengths (shorter than 1 μm) are needed to constrain eruption temperatures. Resolving parts of the lava lake or fountains that are near the eruption temperature is also essential, and we provide a rough estimate of the required image scale.

  2. Development and experimental verification of a robust active noise control system for a diesel engine in submarines

    Science.gov (United States)

    Sachau, D.; Jukkert, S.; Hövelmann, N.

    2016-08-01

    This paper presents the development and experimental validation of an ANC (active noise control)-system designed for a particular application in the exhaust line of a submarine. Thereby, tonal components of the exhaust noise in the frequency band from 75 Hz to 120 Hz are reduced by more than 30 dB. The ANC-system is based on the feedforward leaky FxLMS-algorithm. The observability of the sound pressure in standing wave field is ensured by using two error microphones. The noninvasive online plant identification method is used to increase the robustness of the controller. Online plant identification is extended by a time-varying convergence gain to improve the performance in the presence of slight error in the frequency of the reference signal.

  3. Understanding how active volcanoes work: a contribution from synchrotron X-ray computed microtomography

    Science.gov (United States)

    Polacci, M.; Baker, D. R.; Mancini, L.

    2009-04-01

    Volcanoes are complex systems that require the integration of many different geoscience disciplines to understand their behaviour and to monitor and forecast their activity. In the last two decades an increasing amount of information on volcanic processes has been obtained by studying the textures and compositions of volcanic rocks. Five years ago we started a continuing collaboration with the SYRMEP beamline of Elettra Sincrotrone, a third generation synchrotron light source near Trieste, Italy, with the goal of performing high-resolution, phase-contrast X-ray tomographic scans and reconstructing 3-D digital volumes of volcanic specimens. These volumes have been then used for the visualization of the internal structure of rocks and for the quantification of rock textures (i.e., vesicle and crystal volume fraction, individual vesicle volumes and shapes, vesicle connectivity, vesicle volume distributions, permeability simulations etc.). We performed tomographic experiments on volcanic products erupted from different hazardous volcanic systems in Italy and around the world: Campi Flegrei, Stromboli, Etna (Southern Italy), Villarrica (Chile), Yasur and Ambrym (Vanuatu Islands). As an example, we used the results of these studies to constrain the dynamics of vesiculation and degassing in basaltic (Polacci et al., 2006; Burton et al., 2007; Colò et al., 2007; Andronico et al., 2008; Polacci et al., 2008a) and trachytic (Piochi et al., 2008) magmas. A better knowledge of how gas is transported and lost from magmas has led us in turn to draw new implications on the eruptive style of these active, hazardous volcanoes (Polacci et al., 2008b). Work in progress consists of optimizing our procedure by establishing a precise protocol that will enable us to quantitatively study the 3-D texture and composition of rocks in a statistically representative way. Future work will concentrate on the study of the spatial relations between phases (crystals, vesicles and glass) in rocks

  4. Submarine Medicine Team

    Data.gov (United States)

    Federal Laboratory Consortium — The Submarine Medicine Team conducts basic and applied research on biomedical aspects of submarine and diving environments. It focuses on ways to optimize the health...

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

    Science.gov (United States)

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

    2015-12-01

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

  6. Satellite observations of fumarole activity at Aluto volcano, Ethiopia: Implications for geothermal monitoring and volcanic hazard

    Science.gov (United States)

    Braddock, Mathilde; Biggs, Juliet; Watson, Iain M.; Hutchison, William; Pyle, David M.; Mather, Tamsin A.

    2017-07-01

    Fumaroles are the surface manifestation of hydrothermal circulation and can be influenced by magmatic, hydrothermal, hydrological and tectonic processes. This study investigates the temporal changes in fumarole temperatures and spatial extent on Aluto, a restless volcano in the Main Ethiopian Rift (MER), in order to better understand the controls on fluid circulation and the interaction between the magmatic and hydrothermal systems. Thermal infrared (TIR) satellite images, acquired by the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) over the period of 2004 to 2016, are used to generate time series of the fumarole temperatures and areas. The thermal anomalies identified in the ASTER images coincide with known fumaroles with temperatures > 80 °C and are located on or close to fault structures, which provide a pathway for the rising fluids. Most of the fumaroles, including those along the major zone of hydrothermal upwelling, the Artu Jawe Fault Zone, have pixel-integrated temperature variations of only 2 ± 1.5 °C. The exception are the Bobesa fumaroles located on a hypothesised caldera ring fault which show pixel-integrated temperature changes of up to 9 °C consistent with a delayed response of the hydrothermal system to precipitation. We conclude that fumaroles along major faults are strongly coupled to the magmatic-hydrothermal system and are relatively stable with time, whereas those along shallower structures close to the rift flank are more strongly influenced by seasonal variations in groundwater flow. The use of remote sensing data to monitor the thermal activity of Aluto provides an important contribution towards understanding the behaviour of this actively deforming volcano. This method could be used at other volcanoes around the world for monitoring and geothermal exploration.

  7. Gas fluxes and compositions of two active volcanoes in Northern Chile: Lascar and Lastarria

    Science.gov (United States)

    Tamburello, G.; Hansteen, T. H.; Bredemeyer, S.; Aiuppa, A.; Giudice, G.

    2013-12-01

    The Central Andes Volcanic Zone of northern Chile comprises a ~1200 km long volcanic district extending from the Atacama region on the northe to the Arica and Parinacota region.Lascar and Lastarria are among the most actively degassing volcanoes of the several (more than 30) potentially active in the region. They both host persistent fumarolic fields and generate sustained plumes above the main craters. Here, we report on simultaneous in-situ and remote volcanic gas measurements aimed at obtaining the very first degassing budget for major volatiles released by these fumarolic fields. Using quick deployable scanning DOAS and SO2 camera systems we obtained time-averaged SO2 fluxes of ~ 500 t d-1 and ~ 970 t d-1 for Lascar and Lastarria, respectively. These data were integrated with plume compositional data, obtained using a portable MultiGAS analyzer and sets of base-treated filter packs, to indirectly calculate fluxes of other volcanic species (H2O, CO2, H2, HCl, HF, HBr and HI) from the fumarolic fields. We estimate H2O and CO2 fluxes of ~ 4400 t d-1 and ~ 470 t d-1 for Lascar and ~ 12200 t d-1 and ~ 1100 t d-1 for Lastarria. These numbers are similar to those charcteristic of other medium-sized active subduction zone volcanoes, and out the basis to better constraining the volatile budget for the Northern Chile arc segment.

  8. Santorini Volcano

    Science.gov (United States)

    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.

  9. Eruption of a deep-sea mud volcano triggers rapid sediment movement.

    Science.gov (United States)

    Feseker, Tomas; Boetius, Antje; Wenzhöfer, Frank; Blandin, Jerome; Olu, Karine; Yoerger, Dana R; Camilli, Richard; German, Christopher R; de Beer, Dirk

    2014-11-11

    Submarine mud volcanoes are important sources of methane to the water column. However, the temporal variability of their mud and methane emissions is unknown. Methane emissions were previously proposed to result from a dynamic equilibrium between upward migration and consumption at the seabed by methane-consuming microbes. Here we show non-steady-state situations of vigorous mud movement that are revealed through variations in fluid flow, seabed temperature and seafloor bathymetry. Time series data for pressure, temperature, pH and seafloor photography were collected over 431 days using a benthic observatory at the active Håkon Mosby Mud Volcano. We documented 25 pulses of hot subsurface fluids, accompanied by eruptions that changed the landscape of the mud volcano. Four major events triggered rapid sediment uplift of more than a metre in height, substantial lateral flow of muds at average velocities of 0.4 m per day, and significant emissions of methane and CO₂ from the seafloor.

  10. Observing active deformation of volcanoes in North America: Geodetic data from the Plate Boundary Observatory and associated networks

    Science.gov (United States)

    Puskas, C. M.; Phillips, D. A.; Mattioli, G. S.; Meertens, C. M.; Hodgkinson, K. M.; Crosby, C. J.; Enders, M.; Feaux, K.; Mencin, D.; Baker, S.; Lisowski, M.; Smith, R. B.

    2013-12-01

    The EarthScope Plate Boundary Observatory (PBO), operated by UNAVCO, records deformation of the geologically diverse North America western plate boundary, with subnetworks of instruments concentrated at selected active and potentially active volcanoes. These sensors record deformation and earthquakes and allow monitoring agencies and researchers to analyze changes in ground motion and seismicity. The intraplate volcanoes at Yellowstone and Long Valley are characterized by uplift/subsidence cycles, high seismicity, and hydrothermal activity but there have been no historic eruptions at either volcano. PBO maintains dense GPS networks of 20-25 stations at each of these volcanoes, with an additional 5 boreholes at Yellowstone containing tensor strainmeters, short-period seismometers, and borehole tiltmeters. Subduction zone volcanoes in the Aleutian Arc have had multiple historic eruptions, and PBO maintains equipment at Augustine (8 GPS), Akutan (8 GPS, 4 tiltmeters), and Unimak Island (14 GPS, 8 tiltmeters). The Unimak stations are at the active Westdahl and Shishaldin edifices and the nearby, inactive Isanotski volcano. In the Cascade Arc, PBO maintains networks at Mount St. Helens (15 GPS, 4 borehole strainmeters and seismometers, 8 borehole tiltmeters), Shasta (7 GPS, 1 borehole strainmeter and seismometer), and Lassen Peak (8 GPS). Data from many of these stations in the Pacific Northwest and California are also provided as realtime streams of raw and processed data. Real-time GPS data, along with high-rate GPS data, will be an important new resource for detecting and studying future rapid volcanic deformation events and earthquakes. UNAVCO works closely with the USGS Volcano Hazards Program, archiving data from USGS GPS stations in Alaska, Cascadia, and Long Valley. The PBO and USGS networks combined provide more comprehensive coverage than PBO alone, particularly of the Cascade Arc, where the USGS maintains a multiple instruments near each volcano. Ground

  11. Active hydrocarbon (methane) seepage at the Alboran Sea mud volcanoes indicated by specific lipid biomarkers.

    Science.gov (United States)

    Lopez-Rodriguez, C.; Stadnitskaia, A.; De Lange, G. J.; Martínez-Ruiz, F.; Comas, M.; Sinninghe Damsté, J. S.

    2012-04-01

    Mud volcanoes (MVs) and pockmark fields are known to occur in the Alboran Basin (Westernmost Mediterranean). These MVs occur above a major sedimentary depocenter that includes up to 7 km thick early Miocene to Holocene sequences. MVs located on the top of diapiric structures that originated from undercompacted Miocene clays and olistostromes. Here we provide results from geochemical data-analyses of four gravity cores acquired in the Northern Mud Volcano Field (north of the 36°N): i.e. Perejil, Kalinin and Schneiderś Heart mud expulsion structures. Extruded materials include different types of mud breccias. Specific lipid biomarkers (n-alkanes, hopanes, irregular isoprenoid hydrocarbons and Dialkyl Glycerol Diethers (DGDs) were analysed by gas chromatography (GC) and gas chromatography mass spectrometry (GC-MS). Determination of Glycerol Dialkyl Glycerol Tetraethers (GDGTs) by high performance liquid chromatography-spectrometry (HPLC-MS), and analysis of biomarker δ13C values were performed in selected samples. Lipid biomarker analysis from the three MVs revealed similar n-alkane distributions in all mud breccia intervals, showing significant hydrocarbon-derived signals and the presence of thermally immature organic-matter admixture. This suggests that similar strata fed these MVs. The hemipelagic drapes reveal comparable n-alkane distributions, suggesting that significant upward diffusion of fluids occurs. Distributions of GDGTs are generally accepted as usefull biomarkers to locate the anaerobic oxidation of methane (AOM) in marine sediments. However, our GDGT profiles only reflect the marine thaumarchaeotal signature. There seems to be no archaea producing specific GDGTs involved in AOM in the recovered interval. Evidence of recent activity (i.e., methane gas-bubbling and chemosynthetic fauna at the Perejil MV) and the presence of specific lipid biomarker related with methanotropic archaea (Irregular Isoprenoids and DGDs), however, suggest the existence of

  12. TOMO-ETNA Experiment -Etna volcano, Sicily, investigated with active and passive seismic methods

    Science.gov (United States)

    Luehr, Birger-G.; Ibanez, Jesus M.; Díaz-Moreno, Alejandro; Prudencio, Janire; Patane, Domenico; Zieger, Toni; Cocina, Ornella; Zuccarello, Luciano; Koulakov, Ivan; Roessler, Dirk; Dahm, Torsten

    2017-04-01

    The TOMO-ETNA experiment, as part of the European Union project "MEDiterranean SUpersite Volcanoes (MED-SUV)", was devised to image the crustal structure beneath Etna by using state of the art passive and active seismic methods. Activities on-land and offshore are aiming to obtain new high-resolution seismic images to improve the knowledge of crustal structures existing beneath the Etna volcano and northeast Sicily up to the Aeolian Islands. In a first phase (June 15 - July 24, 2014) at Etna volcano and surrounding areas two removable seismic networks were installed composed by 80 Short Period and 20 Broadband stations, additionally to the existing network belonging to the "Istituto Nazionale di Geofisica e Vulcanologia" (INGV). So in total air-gun shots could be recorded by 168 stations onshore plus 27 ocean bottom instruments offshore in the Tyrrhenian and Ionian Seas. Offshore activities were performed by Spanish and Italian research vessels. In a second phase the broadband seismic network remained operative until October 28, 2014, as well as offshore surveys during November 19 -27, 2014. Active seismic sources were generated by an array of air-guns mounted in the Spanish Oceanographic vessel "Sarmiento de Gamboa" with a power capacity of up to 5.200 cubic inches. In total more than 26.000 shots were fired and more than 450 local and regional earthquakes could be recorded and will be analyzed. For resolving a volcanic structure the investigation of attenuation and scattering of seismic waves is important. In contrast to existing studies that are almost exclusively based on S-wave signals emitted by local earthquakes, here air-gun signals were investigated by applying a new methodology based on the coda energy ratio defined as the ratio between the energy of the direct P-wave and the energy in a later coda window. It is based on the assumption that scattering caused by heterogeneities removes energy from direct P-waves that constitutes the earliest possible

  13. Ionospheric Disturbances Recorded by DEMETER Satellite over Active Volcanoes: From August 2004 to December 2010

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    Jacques Zlotnicki

    2013-01-01

    Full Text Available The study analyzes electromagnetic data and plasma characteristics in the ionosphere recorded by DEMETER microsatellite over erupting volcanoes during the life of the mission: from August 2004 to December 2010. The time window in which anomalous changes are searched brackets the onset of the eruptive activity from 60 days before to 15 days after the period during which most pre- and posteruptive phenomena are amplified. 73 volcanoes have entered into eruption. For 58 of them, 269 anomalies were found in relation to 89 eruptions. They are distributed in 5 types, similarly to the ones observed above impeding earthquakes. The two main types are electrostatic turbulence (type 1, 23.4% and electromagnetic emissions (type 2, 69.5%. The maximum number of types 1 and 2 anomalies is recorded between 30 and 15 days before the surface activity, corresponding to the period of accelerating phenomena. The amount of anomalies seems related to the powerfulness of the eruptions. The appearance seems dependant on the likelihood to release bursts of gases during the preparatory eruptive phase. For the huge centenary October 26, 2010, Merapi (Indonesia eruption, 9 ionospheric type 2 anomalies appeared before the eruption. They mainly emerge during the mechanical fatigue stage during which microfracturing occurs.

  14. Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems

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    Franco Tassi

    2010-03-01

    Full Text Available The composition of non-methane organic volatile compounds (VOCs determined in 139 thermal gas discharges from 18 different geothermal and volcanic systems in Italy and Latin America, consists of C2–C20 species pertaining to the alkanes, alkenes, aromatics and O-, S- and N-bearing classes of compounds. Thiophenes and mono-aromatics, especially the methylated species, are strongly enriched in fluids emissions related to hydrothermal systems. Addition of hydrogen sulphide to dienes and electrophilic methylation involving halogenated radicals may be invoked for the formation of these species. On the contrary, the formation of furans, with the only exception of C4H8O, seems to be favoured at oxidizing conditions and relatively high temperatures, although mechanisms similar to those hypothesized for the production of thiophenes can be suggested. Such thermodynamic features are typical of fluid reservoirs feeding high-temperature thermal discharges of volcanoes characterised by strong degassing activity, which are likely affected by conspicuous contribution from a magmatic source. The composition of heteroaromatics in fluids naturally discharged from active volcanoes and geothermal areas can then be considered largely dependent on the interplay between hydrothermal vs. magmatic contributions. This implies that they can be used as useful geochemical tools to be successfully applied in both volcanic monitoring and geothermal prospection.

  15. Near-Real time analysis of seismic data of active volcanoes: Software implementations of time sequence data analysis

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    J. Vila

    2008-07-01

    Full Text Available This paper presents the development and applications of a software-based quality control system that monitors volcano activity in near-real time. On the premise that external seismic manifestations provide information directly related to the internal status of a volcano, here we analyzed variations in background seismic noise. By continuous analysis of variations in seismic waveforms, we detected clear indications of changes in the internal status. The application of this method to data recorded in Villarrica (Chile and Tungurahua (Ecuador volcanoes demonstrates that it is suitable to be used as a forecasting tool. A recent application of this developed software-based quality control to the real-time monitoring of Teide – Pico Viejo volcanic complex (Spain anticipated external episodes of volcanic activity, thus corroborating the advantages and capacity of the methodology when implemented as an automatic real-time procedure.

  16. Anomalous changes of diffuse CO_{2} emission and seismic activity at Teide volcano, Tenerife, Canary Islands

    Science.gov (United States)

    García-Hernández, Rubén; Melián, Gladys; D'Auria, Luca; Asensio-Ramos, María; Alonso, Mar; Padilla, Germán D.; Rodríguez, Fátima; Padrón, Eleazar; Barrancos, José; García-Merino, Marta; Amonte, Cecilia; Pérez, Aarón; Calvo, David; Hernández, Pedro A.; Pérez, Nemesio M.

    2017-04-01

    Tenerife (2034 km2) is the largest of the Canary Islands and hosts four main active volcanic edifices: three volcanic rifts and a central volcanic complex, Las Cañadas, which is characterized by the eruption of differentiated magmas. Laying inside Las Cañadas a twin stratovolcanoes system, Pico Viejo and Teide, has been developed. Although there are no visible gas emanations along the volcanic rifts of Tenerife, the existence of a volcanic-hydrothermal system beneath Teide volcano is suggested by the occurrence of a weak fumarolic system, steamy ground and high rates of diffuse CO2 degassing all around the summit cone of Teide. Soil CO2 efflux surveys have been performed at the summit crater of Teide volcano since 1999, to determine the diffuse CO2 emission from the summit crater and to evaluate the temporal variations of CO2 efflux and their relationships with seismic-volcanic activity. Soil CO2 efflux and soil temperature have been always measured at the same 38 observation sites homogeneously distributed within an area of about 6,972 m2 inside the summit crater. Soil CO2 diffuse effluxes were estimated according to the accumulation chamber method by means of a non-dispersive infrared (NDIR) LICOR-820 CO2 analyzer. Historical seismic activity in Tenerife has been characterized by low- to moderate-magnitude events (M <2.5), and most of the earthquake's epicenters have been clustered in an offshore area SE of Tenerife. However, very few earthquakes have occurred in other areas, including Teide volcano. At 12:18 of January 6, 2017, the Canary Seismic Network belonged to the Instituto Volcanológico de Canarias (INVOLCAN) registered an earthquake of M 2.5 located in the vertical of Teide volcano with a depth of 6.6 km. It was the strongest earthquake located inside Cañadas caldera since 2004. Between October 11 and December 13, 2016, a continuous increase on the diffuse CO2 emission was registered, from 21.3 ± 2.0 to 101.7 ± 20.7 t d-1, suggesting the occurrence

  17. Database for the Geologic Map of the Summit Region of Kilauea Volcano, Hawaii

    Science.gov (United States)

    Dutton, Dillon R.; Ramsey, David W.; Bruggman, Peggy E.; Felger, Tracey J.; Lougee, Ellen; Margriter, Sandy; Showalter, Patrick; Neal, Christina A.; Lockwood, John P.

    2007-01-01

    INTRODUCTION The area covered by this map includes parts of four U.S. Geological Survey (USGS) 7.5' topographic quadrangles (Kilauea Crater, Volcano, Ka`u Desert, and Makaopuhi). It encompasses the summit, upper rift zones, and Koa`e Fault System of Kilauea Volcano and a part of the adjacent, southeast flank of Mauna Loa Volcano. The map is dominated by products of eruptions from Kilauea Volcano, the southernmost of the five volcanoes on the Island of Hawai`i and one of the world's most active volcanoes. At its summit (1,243 m) is Kilauea Crater, a 3 km-by-5 km collapse caldera that formed, possibly over several centuries, between about 200 and 500 years ago. Radiating away from the summit caldera are two linear zones of intrusion and eruption, the east and the southwest rift zones. Repeated subaerial eruptions from the summit and rift zones have built a gently sloping, elongate shield volcano covering approximately 1,500 km2. Much of the volcano lies under water: the east rift zone extends 110 km from the summit to a depth of more than 5,000 m below sea level; whereas, the southwest rift zone has a more limited submarine continuation. South of the summit caldera, mostly north-facing normal faults and open fractures of the Koa`e Fault System extend between the two rift zones. The Koa`e Fault System is interpreted as a tear-away structure that accommodates southward movement of Kilauea's flank in response to distension of the volcano perpendicular to the rift zones. This digital release contains all the information used to produce the geologic map published as USGS Geologic Investigations Series I-2759 (Neal and Lockwood, 2003). The main component of this digital release is a geologic map database prepared using ArcInfo GIS. This release also contains printable files for the geologic map and accompanying descriptive pamphlet from I-2759.

  18. Capturing the fingerprint of Etna volcano activity in gravity and satellite radar data

    Science.gov (United States)

    Negro, Ciro Del; Currenti, Gilda; Solaro, Giuseppe; Greco, Filippo; Pepe, Antonio; Napoli, Rosalba; Pepe, Susi; Casu, Francesco; Sansosti, Eugenio

    2013-01-01

    Long-term and high temporal resolution gravity and deformation data move us toward a better understanding of the behavior of Mt Etna during the June 1995 – December 2011 period in which the volcano exhibited magma charging phases, flank eruptions and summit crater activity. Monthly repeated gravity measurements were coupled with deformation time series using the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique on two sequences of interferograms from ERS/ENVISAT and COSMO-SkyMed satellites. Combining spatiotemporal gravity and DInSAR observations provides the signature of three underlying processes at Etna: (i) magma accumulation in intermediate storage zones, (ii) magmatic intrusions at shallow depth in the South Rift area, and (iii) the seaward sliding of the volcano's eastern flank. Here we demonstrate the strength of the complementary gravity and DInSAR analysis in discerning among different processes and, thus, in detecting deep magma uprising in months to years before the onset of a new Etna eruption. PMID:24169569

  19. Social studies of volcanology: knowledge generation and expert advice on active volcanoes

    Science.gov (United States)

    Donovan, Amy; Oppenheimer, Clive; Bravo, Michael

    2012-04-01

    This paper examines the philosophy and evolution of volcanological science in recent years, particularly in relation to the growth of volcanic hazard and risk science. It uses the lens of Science and Technology Studies to examine the ways in which knowledge generation is controlled and directed by social forces, particularly during eruptions, which constitute landmarks in the development of new technologies and models. It also presents data from a survey of volcanologists carried out during late 2008 and early 2009. These data concern the felt purpose of the science according to the volcanologists who participated and their impressions of the most important eruptions in historical time. It demonstrates that volcanologists are motivated both by the academic science environment and by a social concern for managing the impact of volcanic hazards on populations. Also discussed are the eruptions that have most influenced the discipline and the role of scientists in policymaking on active volcanoes. Expertise in volcanology can become the primary driver of public policy very suddenly when a volcano erupts, placing immense pressure on volcanologists. In response, the epistemological foundations of volcanology are on the move, with an increasing volume of research into risk assessment and management. This requires new, integrated methodologies for knowledge collection that transcend scientific disciplinary boundaries.

  20. Long-Term Volcanic Activity at Shiveluch Volcano: Nine Years of ASTER Spaceborne Thermal Infrared Observations  

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    Adam Carter

    2010-11-01

    Full Text Available Shiveluch (Kamchatka, Russia is the most active andesitic volcano of the Kuril-Kamchatka arc, typically exhibiting near-continual high-temperature fumarolic activity and periods of exogenous lava dome emplacement punctuated by discrete large explosive eruptions. These eruptions can produce large pyroclastic flow (PF deposits, which are common on the southern flank of the volcano. Since 2000, six explosive eruptions have occurred that generated ash fall and PF deposits. Over this same time period, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER instrument has been acquiring image-based visible/near infrared (VNIR, short wave infrared (SWIR and thermal infrared (TIR data globally, with a particular emphasis on active volcanoes. Shiveluch was selected as an ASTER target of interest early in the mission because of its frequent activity and potential impact to northern Pacific air transportation. The north Pacific ASTER archive was queried for Shiveluch data and we present results from 2000 to 2009 that documents three large PF deposits emplaced on 19 May 2001, 9 May 2004, and 28 February 2005. The long-term archive of infrared data provides an excellent record on the changing activity and eruption state of the volcano.

  1. Plant growth-promoting potential of bacteria isolated from active volcano sites of Barren Island, India.

    Science.gov (United States)

    Amaresan, N; Kumar, K; Sureshbabu, K; Madhuri, K

    2014-02-01

    To elucidate the biodiversity of plant growth-promoting (PGP) bacteria in active volcano sites of Barren Island, India, a total of 102 bacteria were isolated and screened for their multifunctional PGP properties. The results revealed that 21 isolates (20.6%) survived heat shock at 72°C and 11 (10.8%) isolates were able to grow exposed to 25% NaCl (w/v). In assaying for PGP properties, 59 (57.8%) isolates shown indole acetic acid (IAA) like substances production, 57 isolates (55.9%) produced siderophore and 34 (33.3%) solubilized inorganic phosphate qualitatively. Whereas in the production of extracellular enzymes, 42 isolates (41.2%) produced protease and amylase, 26 (25.5%) isolates produced lipase and 24 (23.5%) isolates produced cellulase. In antagonistic activity, 30 isolates (29.4%) were found antagonistic against Macrophomina sp., 20 isolates (19.6%) against Rhizoctonia solani and 15 isolates (14.7%) against Sclerotium rolfsii. The results based on 16 rRNA gene sequencing revealed that the PGP bacteria belonged to 22 different species comprising 13 genera. Based on multifunctional properties, nine isolates were further selected to determine the PGP in brinjal and chilli seeds. Of the bacteria tested, the isolate BAN87 showed increased root and shoot length of both the crops followed in plant growth promotion by BAN86 and BAN43. The outcome of this research proves plausible practical applicability of these PGPB for crop production in soils of saline and arid environments. The present research shows diverse plant growth-promoting (PGP) bacteria could be isolated from the active volcano site and suggests that volcano sites represent an ecological niche, which harbours a diverse and hitherto largely uncharacterized microbial population with yet unknown and untapped potential biotechnological applications, for example, plant growth promoters, as evidenced from this study. The outcome of this research may have a practical effect on crop production methodologies in

  2. Visions of Volcanoes

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    David M. Pyle

    2017-12-01

    Full Text Available The long nineteenth century marked an important transition in the understanding of the nature of combustion and fire, and of volcanoes and the interior of the earth. It was also a period when dramatic eruptions of Vesuvius lit up the night skies of Naples, providing ample opportunities for travellers, natural philosophers, and early geologists to get up close to the glowing lavas of an active volcano. This article explores written and visual representations of volcanoes and volcanic activity during the period, with the particular perspective of writers from the non-volcanic regions of northern Europe. I explore how the language of ‘fire’ was used in both first-hand and fictionalized accounts of peoples’ interactions with volcanoes and experiences of volcanic phenomena, and see how the routine or implicit linkage of ‘fire’ with ‘combustion’ as an explanation for the deep forces at play within and beneath volcanoes slowly changed as the formal scientific study of volcanoes developed. I show how Vesuvius was used as a ‘model’ volcano in science and literature and how, later, following devastating eruptions in Indonesia and the Caribbean, volcanoes took on a new dimension as contemporary agents of death and destruction.

  3. A Wireless Seismoacoustic Sensor Network for Monitoring Activity at Volcano Reventador, Ecuador

    Science.gov (United States)

    Welsh, M.; Werner-Allen, G.; Lorincz, K.; Marcillo, O.; Ruiz, M.; Johnson, J.; Lees, J. M.

    2005-12-01

    We developed a wireless sensor network for monitoring seismoacoustic activity at Volcano Reventador, Ecuador. Wireless sensor networks are a new technology and our group is among the first to apply them to monitoring volcanoes. The small size, low power, and wireless communication capabilities can greatly simplify deployments of large sensor arrays. The network consisted of 16 wireless sensor nodes, each outfitted with an 8 MHz CPU (TI MSP430) and a 2.4 GHz IEEE 802.15.4 radio (Chipcon CC2420) with data rates up to 80 Kbps. Each node acquired acoustic and seismic data at 24-bit resolution, with a microphone and either a single-axis geophone or triaxial short-period seismometer. Each node is powered by two D-cell batteries with a lifetime of about 1 week, and measures 18 x 10 x 8 cm. Nodes were distributed radially from the vent over a 3 km aperture. Control and data messages are relayed via radio to a base station node, with inter-node distances of up to 420 m. The base station transmits data using a FreeWave radio modem, via a repeater, to a laptop located 4 km from the deployment site. Each node samples continuous sensor data and a simple event-detection algorithm is used to trigger data collection. When a sensor detects an event, it relays a short message to the base station via radio. If several nodes report an event within a short time interval, the last 60 seconds of data is downloaded from each node in turn. One of the sensor nodes is programmed to transmit continuous data; due to limited radio bandwidth, it is not possible to collect continuous data from all nodes in the array. A GPS receiver and time synchronization protocol is used to establish a global timebase across all sensor nodes.

  4. Multidisciplinary research for the safe fruition of an active geosite: the Salse di Nirano mud volcanoes (Northern Apennines, Italy)

    Science.gov (United States)

    Coratza, Paola; Albarello, Dario; Cipriani, Anna; Cantucci, Barbara; Castaldini, Doriano; Conventi, Marzia; Dadomo, Andrea; De Nardo, Maria Teresa; Macini, Paolo; Martinelli, Giovanni; Mesini, Ezio; Papazzoni, Cesare Andrea; Quartieri, Simona; Ricci, Tullio; Santagata, Tommaso; Sciarra, Alessandra; Vezzalini, Giovanna

    2017-04-01

    Mud volcanoes are emissions of cold mud due to the ascent to the surface of salty and muddy waters mixed with gaseous (methane) and, in minor part, fluid hydrocarbons (petroleum veils) along faults and fractures. In the Northern Apennines mud volcanoes are closely linked to the active tectonic compression associated with thrusts of regional importance. They are mostly cone-shaped and show variable geometry and size, ranging from one to few metres, and are located in 19 sites in the northwestern part of the Apennines. Particularly noteworthy is the Nirano mud volcano field, located in the Fiorano Modenese district, which, with a surface area of approximately 75,000 m2, is one of the best developed and largest mud volcano field of the entire Italian territory and among the largest in Europe; it is thus protected as natural reserve (Salse di Nirano) since 1982. The Nirano mud volcanoes are found at the bottom of an elliptical depression, interpreted as a collapse-like structure (caldera) that may have developed in response to the deflation of a shallow mud chamber triggered by several ejections and evacuation of fluid sediments. There are several individual or multiple cones within the field of the mud volcanoes of Nirano, with a rather discontinuous activity; apparatuses become dormant or even extinct whereas new vents can appear in other spots. In the research here presented about 50 vents have been mapped and few of them appeared in May 2016. The mud volcanoes of the region have been known since a long time and have always aroused great interest due to their outstanding scenic value, and, in the past the mud volcano emissions have been used in many ways. Beside their cultural value, the mud volcanoes of the study area represent a tourist attractiveness as testified by the increasing number of visitors (e.g. about 70,000 visitors in 2015 in the Salse di Nirano Natural Reserve). Numerous initiatives, targeted at various potential users, have been developed in the

  5. Cotopaxi volcano's unrest and eruptive activity in 2015: mild awakening after 73 years of quiescence

    Science.gov (United States)

    Hidalgo, Silvana; Bernard, Benjamin; Battaglia, Jean; Gaunt, Elizabeth; Barrington, Charlotte; Andrade, Daniel; Ramón, Patricio; Arellano, Santiago; Yepes, Hugo; Proaño, Antonio; Almeida, Stefanie; Sierra, Daniel; Dinger, Florian; Kelly, Peter; Parra, René; Bobrowski, Nicole; Galle, Bo; Almeida, Marco; Mothes, Patricia; Alvarado, Alexandra

    2016-04-01

    Cotopaxi volcano (5,897 m) is located 50 km south of Quito, the capital of Ecuador. The most dangerous hazards of this volcano are the devastating lahars that can be generated by the melting of its ice cap during pyroclastic flow-forming eruptions. The first seismic station was installed in 1976. Cotopaxi has been monitored by the Instituto Geofísico (Escuela Politécnica Nacional) since 1983. Presently the monitoring network is comprised of 11 broadband and 5 short period seismometers, 4 scanning DOAS, 1 infrared and 5 visible cameras, 7 DGPS, 5 tiltmeters, 11 AFM (lahar detectors) and a network of ashmeters. Due to the recent unrest, the monitoring of the volcano has been complemented by campaign airborne Multi-GAS and thermal IR measurements and ground-based mobile DOAS and stationary solar FTIR. After 73 years of quiescence, the first sign of unrest was a progressive increase in the amplitude of transient seismic events in April 2015. Since May 20, an increase in SO2 emissions from ˜500 t/d to ˜3 kt/day was detected followed by the appearance of seismic tremor on June 4. Both SO2 emissions of up to 5 kt/day and seismic tremor were observed until August 14 when a swarm of volcano-tectonic earthquakes preceded the first phreatic explosions. These explosions produced ash and gas columns reaching up to 9 km above the crater. The ash fall produced by the opening phase covered over 500 km2 with a submillimetric deposit corresponding to a mass of 1.65E+8 kg (VEI 1). During this period of explosions, SO2 emission rates up to 24 kt/day were observed, the highest thus far. The ash was dominantly hydrothermally altered and oxidized lithic fragments, hydrothermal minerals (alunite, gypsum), free crystals of plagioclase and pyroxenes, and little juvenile material. Unrest continued after August 14, with three episodes of ash emission. However, the intensity of ash fallout, average seismic amplitude, and SO2 emissions during each successive episode progressively decreased

  6. Volcanoes - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer includes Holocene volcanoes, which are those thought to be active in the last 10,000 years, that are within an extended area of the northern...

  7. Thermal Activity Monitoring of an Active Volcano Using Landsat 8/OLI-TIRS Sensor Images: A Case Study at the Aso Volcanic Area in Southwest Japan

    Directory of Open Access Journals (Sweden)

    Md. Bodruddoza Mia

    2017-11-01

    Full Text Available Thermal remote sensing is currently an emerging technique for monitoring active volcanoes around the world. The study area, the Aso volcano, is currently the most active and has erupted almost every year since 2012. For the first time, Landsat 8 TIRS thermal data were used in this study area to evaluate and monitor the recent thermal status of this volcano, situated in Southwest Japan, from 2013 to 2016 using four sets of images. The total heat discharged rate (HDR, radiative heat flux (RHF, land surface temperature (LST, and land cover (LC were evaluated, and the relationship between them was determined, to understand the thermal status of the study area. We used the NDVI (normalized difference vegetation index for land cover, the NDVI-threshold method for emissivity, the split-window algorithm for LST, and the Stefan–Boltzmann equation for radiative heat flux estimation in this study. The total heat discharge rate was computed using a relationship coefficient of RHF and HDR here. The highest HDR was obtained in 2013, at about 4715 MW, and was the lowest in 2016, at about 3819 MW. The total heat loss showed a declining trend, overall, from 2013 to 2016. The highest pixel RHF was in 2013 and the lowest was in 2014; after that, it increased gradually until 2016, coinciding with the LST of this study area. LC showed that, with decreasing heat loss, the vegetated coverage increased and bare land or mixed land decreased, and vice versa. From the spatial distribution of RHF, we saw that, within the Nakadake craters of the Aso volcano, Crater 1 was the most active part of this volcano throughout the study period, and Crater 3 was the most active after 2014. We inferred that the applied methods using the continuous Landsat 8 TIRS data showed an effective and efficient method of monitoring the thermal status of this active volcano.

  8. The PROTEUS Experiment: Active Source Seismic Imaging of the Crustal Magma Plumbing Structure of the Santorini Arc Volcano

    Science.gov (United States)

    Hooft, E. E. E.; Morgan, J. V.; Nomikou, P.; Toomey, D. R.; Papazachos, C. V.; Warner, M.; Heath, B.; Christopoulou, M. E.; Lampridou, D.; Kementzetzidou, D.

    2016-12-01

    The goal of the PROTEUS seismic experiment (Plumbing Reservoirs Of The Earth Under Santorini) is to examine the entire crustal magma plumbing system beneath a continental arc volcano and determine the magma geometry and connections throughout the crust. These physical parameters control magma migration, storage, and eruption and inform the question of how physical and chemical processing of magma at arc volcanoes forms the andesitic rock compositions that dominate the lower continental crust. These physical parameters are also important to understand volcanic-tectonic interactions and geohazards. Santorini is ideal for these goals because the continental crust has been thinned by extension and so the deep magmatic system is more accessible, also it is geologically well studied. Since the volcano is a semi-submerged, it was possible to collect a unique 3D marine-land active source seismic dataset. During the PROTEUS experiment in November-December of 2015, we recorded 14,300 marine sound sources from the US R/V Langseth on 89 OBSIP short period ocean bottom seismometers and 60 German and 5 Greek land seismometers. The experiment was designed for high-density spatial sampling of the seismic wavefield to allow us to apply two state-of-the-art 3D inversion methods: travel time tomography and full waveform inversion. A preliminary travel time tomography model of the upper crustal seismic velocity structure of the volcano and surrounding region is presented in an accompanying poster. We also made marine geophysical maps of the seafloor using multi-beam bathymetry and of the gravity and magnetic fields. The new seafloor map reveals the detailed structure of the major fault system between Santorini and Amorgos, of associated landslides, and of newly discovered volcanic features. The PROTEUS project will provide new insights into the structure of the whole crustal magmatic system of a continental arc volcano and its evolution within the surrounding tectonic setting.

  9. Lightning and electrical activity during the Shiveluch volcano eruption on 16 November 2014

    National Research Council Canada - National Science Library

    Boris M Shevtsov; Pavel P Firstov; Nina V Cherneva; Robert H Holzworth; Renat R Akbashev

    2016-01-01

      According to World Wide Lightning Location Network (WWLLN) data, a sequence of lightning discharges was detected which occurred in the area of the explosive eruption of Shiveluch volcano on 16 November 2014 in Kamchatka...

  10. Employment of broadband seismometers to conduct micro-gravity monitoring surveys on active volcanoes

    Science.gov (United States)

    Caravantes, G.; Gómez-Izquierdo, B.; Rymer, H.; Matela, R. J.

    2009-04-01

    Micro-gravity monitoring through discrete measurements can be used at active volcanoes to identify and model processes within the volcanic system. Mass redistributions occurring over a wide range of depths can be detected. However, the lack of information on the rate at which volcanic processes occur (due to time lapse between successive surveys) limits considerably this method. Continuous gravity changes in volcanic environments can constrain fluid and gas transport at depth. This method does, nevertheless, have some drawbacks. The high cost of gravity meters prevents observatories deploying arrays of these instruments. Thus the temporal advantage of continuous gravity measurements is outweighed by the spatial disadvantage of this type of monitoring compared with traditional micro-gravity. Apart from conventional gravimeters, good quality gravity data can also be retrieved from digital records of the output of broadband seismometers. In this work, we analyse several constituents of the geophysical noise affecting the signal. Factors such as the oceanic loading and subsequent tilt can have an important effect on the record, especially for coastal stations. These disturbances are registered by the two horizontal components of tri-axial broadband seismometers, which can be used to identify the contribution of different observable noise sources, allowing application of various corrections to the data and removal from the signal obtained from vertical sensors. Finally, the possibility of continuously measuring micro-gravity changes using broadband seismometers in the field is discussed, with a special emphasis on the complex multi-parameter settings that we find in active volcanoes. The relatively low cost and portability of these devices may make them suitable for the deployment of networks investigating gravitational effect produced by volcanic and magmatic processes. References: - S. Lambotte, L. Rivera and J. Hinderer (2006). Vertical and horizontal seismometric

  11. Radon surveys and monitoring at active volcanoes: an open window on deep hydrothermal systems and their dynamics

    Science.gov (United States)

    Cigolini, Corrado; Laiolo, Marco; Coppola, Diego

    2017-04-01

    The behavior of fluids in hydrothermal systems is critical in volcano monitoring and geothermal prospecting. Analyzing the time series of radon emissions on active volcanoes is strategic for detecting and interpreting precursory signals of changes in volcanic activity, eventually leading to eruptions. Radon is a radioactive gas generated from the decay of U bearing rocks, soils and magmas. Although radon has been regarded as a potential precursor of earthquakes, radon anomalies appear to be better suited to forecast volcanic eruptions since we know where paroxysms may occur and we can follow the evolution of volcanic activity. Radon mapping at active volcanoes is also a reliable tool to assess diffuse and concentrated degassing as well as efficiently detecting earthquake-volcano interactions. Systematic radon monitoring has been shown to be a key factor for evaluating the rise of volcanic and hydrothermal fluids. In fact, the decay properties of radon, the duration of radon anomalies together with sampling rates may be cross-checked with the chemistry of hydrothermal fluids (and their transport properties) to constrain fluids ascent rates and to infer the permeability and porosity of rocks in sectors surrounding the active conduits. We hereby further discuss the data of radon surveys and monitoring at Somma-Vesuvius, Stromboli and La Soufrière (Guadeloupe, Lesser Antilles). The integrated analysis of seismic and geochemical data, including radon emissions, may be successfully used in testing temperature distributions and variations of porosity and permeability in volcanic hydrothermal systems and can be used as a proxy to analyze geothermal reservoirs.

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

    Science.gov (United States)

    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

  13. Explosive Activity at Tungurahua Volcano: Analysis of Seismic and Infrasonic Data from 2006 - 2011

    Science.gov (United States)

    Steele, A. L.; Ruiz, M. C.; Lyons, J. J.

    2012-12-01

    Tungurahua is an active, steep-sided andesitic stratovolcano, located in central Ecuador. Historic eruptions are characterized by strong explosions, lava and pyroclastic flows, lahars and tephra fallout. After 75 years of quiescence, a renewed phase of explosive activity began in October 1999. Since, Tungurahua has experienced a series of eruptive cycles, with almost continuous activity separated by only short periods (months) of repose. We apply several statistical techniques to a continuous catalog of over 4500 volcanic explosions, recorded between July 2006 and May 2011. Reduced amplitudes and energies are calculated for each event using four collocated broadband seismic and infrasound sensors. An initial time series analysis isolates 8 phases of activity: Jul-Aug 2006, Feb-Apr 2007, Jul 2007-Feb 2008, Mar 2008-Jun 2009, Jan-Mar 2010, May-Jul 2010, Nov-Dec 2010 and Apr-May 2011. Small temporal changes in the volcanic eruption mechanism across successive episodes are identified by a lack of dependency in event rate auto-correlation and a continuous fluctuation in the proxy b-value of moving-window, frequency-amplitude distributions. We highlight the May-July 2010 episode because it is statistically distinct from the other periods of explosive activity. Peak explosion event rate during this time is approximately six times that of any other episode across the observation period (max ~ 242 events; 31 May 2010), while cumulative daily seismo-acoustic explosion energies are at least an order of magnitude greater. The coefficient of variation (Cv = σ/μ, where; σ is the standard deviation; and μ is the mean repose time of explosions) is used to show a strong clustering of events with time (episodes 1-5 & 7-8 = Cv ~ 2-5) and not representative of a Poisson controlled process. A Cv ~ 13.7 in May-July 2010 (episode 6) further highlights the anomalous nature of activity during this period. The volcano acoustic-seismic ratio (VASR, or η), the ratio of elastic energy

  14. Low cost submarine robot

    OpenAIRE

    Ponlachart Chotikarn; Werapong Koedsin; Boonlua Phongdara; Pattara Aiyarak

    2010-01-01

    A submarine robot is a semi-autonomous submarine robot used mainly for marine environmental research. We aim todevelop a low cost, semi-autonomous submarine robot which is able to travel underwater. The robot’s structure was designedand patented using a novel idea of the diving system employing a volume adjustment mechanism to vary the robot’s density.A light weight, flexibility and small structure provided by PVC can be used to construct the torpedo-liked shape robot.Hydraulic seal and O-rin...

  15. Low cost submarine robot

    Directory of Open Access Journals (Sweden)

    Ponlachart Chotikarn

    2010-10-01

    Full Text Available A submarine robot is a semi-autonomous submarine robot used mainly for marine environmental research. We aim todevelop a low cost, semi-autonomous submarine robot which is able to travel underwater. The robot’s structure was designedand patented using a novel idea of the diving system employing a volume adjustment mechanism to vary the robot’s density.A light weight, flexibility and small structure provided by PVC can be used to construct the torpedo-liked shape robot.Hydraulic seal and O-ring rubbers are used to prevent water leaking. This robot is controlled by a wired communicationsystem.

  16. Cyclic activity at silicic volcanoes: A response to dynamic permeability variations

    Science.gov (United States)

    Lamur, Anthony; Lavallée, Yan; Kendrick, Jackie; Eggertsson, Gudjon; Ashworth, James; Wall, Richard

    2017-04-01

    Silicic volcanoes exhibit cyclic eruptive activity characterised by effusive (dome growth) to quiescent periods punctuated by short explosive episodes. The latter, characterised by fast emissions of gas and ash into the atmosphere, results from stress release through fracturing and causes significant hazards to the surrounding environment. Understanding the formation, development and closure of fractures as well as their impact on the volcanic system is hence vital for better constraining current models. Here, we present the results of two sets of experiments designed to understand first, the development of permeability through fracturing and second, the timescale over which these fractures can persist in magmas. To characterise the influence of a macro-fracture, the permeability of intact volcanic rocks with a wide porosity range (1-41%) was measured at varying effective pressures (-0.001-30 MPa). We then fractured each sample using the Brazilian disc method to induce a tensile macro-fracture, before measuring the permeability under the same conditions. While our results for intact samples are consistent with previous studies, the results for fractured samples display a distinct permeability-porosity relationship. We show that low porosity samples (up to 4 orders of magnitude upon fracturing, compared to high porosity samples (>18%) that show a less than 1 order of magnitude increase. This suggests that a macro-fracture has the ability to efficiently localise the flow in low porosity rocks by becoming the prevailing structure in a previously micro-fracture-dominated porous network, whereas at higher porosities fluid flow remains controlled by pore connectivity, irrespective of the presence of a fracture. To assess the longevity of fractures in magmas we developed a novel experimental set-up, in which two glass rods were placed in contact for different timescales at high temperatures before being pulled apart to test the tensile strength recovery of the fracture

  17. Distribution of Gassy Sediments and Mud Volcanoes Offshore Southwestern Taiwan

    Directory of Open Access Journals (Sweden)

    Jui-Kun Chiu

    2006-01-01

    Full Text Available This study presents the results from recent intense marine geophysical surveys conducted offshore of southwestern Taiwan. Mud volcanoes and gassy sediments have been identified along chirp sonar and seismic reflection profile data. The distribution of gassy sediments and mud volcanoes has been compiled, showing these features extending from the accretionary wedge to the passive China continental margin. Submarine mud volcanoes could be grouped into four main clusters in the accretionary wedge province: offshore Kaohsiung, adjacent to the Kaoping Submarine Canyon, near the head of the Fangliao Submarine Canyon and along the Yung-An Lineament. Each cluster is composed of a few to more than 10 submarine mud volcanoes. Their origin could be related to gas hydrate dissociation with rising highpressure fluid along faults or mud diapir piercing the seafloor. These gassy sediments and mud volcanoes could be formed by fluids escaping from dewatering sedimentary layers of mud diapirs, or along faults and fractures where free gases or gases dissociating from hydrates migrate to the seafloor.

  18. Changes of biogeochemical activities before and after significant mud displacement at the Håkon Mosby Mud Volcano (HMMV)

    Science.gov (United States)

    Felden, J.; Wenzhöfer, F.; Yoerger, D.; Camilli, R.; German, C.; Olu, K.; Feseker, T.; de Beer, D.; Boetius, A.

    2012-04-01

    The Håkon Mosby Mud Volcano (72°N, 14° 43' E, 1250 m water depth) was studied for a period of a year by the Long-term Observatory On Mud-volcano Eruptions (LOOME) in 2009-2010, to investigate temporal variations of mud volcanism and consequences for biogeochemical processes. The HMMV is a highly active methane cold seep ecosystem characterized by high rates of methane efflux. It hosts different chemosynthetic communities such as thiotrophic bacterial mats and siboglinid tubeworm assemblages. This study focuses on changes in community composition and biogeochemical activity such as methane emission, total benthic oxygen uptake, microbial methane and sulfate consumption before and after a major mud displacement recorded by LOOME. The sensor-enabled long-term observations of the HMMV habitats were combined with short-term analyses before and after the displacement events by ROVs QUEST (MARUM) and GENESIS (University of Gent), the AUV Sentry (WHOI) equipped with a multibeam and subbottom profiler, CTD and photographic unit as well as with a mass spectrometer. We found shifts in the distribution patterns of chemosynthetic communities and also substantial changes in their activity, consistent with changes in temperature gradients. This study was sponsored by the EU-Projects HERMIONE "Hotspot Ecosystem Research and Man's Impact on European Seas", and ESONET "European Seas Observatory Network" (Demonstration Mission LOOME "Long term observations on mud volcano eruptions").

  19. Locadiff with ambient seismic noise : theoretical background and application to monitoring volcanoes and active faults.

    Science.gov (United States)

    Larose, Eric; Obermann, Anne; Planes, Thomas; Rossetto, Vincent; Margerin, Ludovic; Sens-Schoenfelder, Christoph; Campillo, Michel

    2015-04-01

    This contribution will cover recent theoretical, numerical, and field data processing developments aiming at modeling how coda waves are perturbed (in phase and amplitude) by mechanical changes in the crust. Using continuous ambient seismic noise, we cross-correlate data every day and compare the coda of the correlograms. We can relative velocity changes and waveform decorrelation along the year, that are related to mechanical changes in the shallow crust, associated to the seismic or volcanic activity, but also to environmental effects such as hydrology. Bibliography : Anne Obermann, Thomas Planes, Eric Larose and Michel Campillo, Imaging pre- and co-eruptive structural changes of a volcano with ambient seismic noise, J. Geophys. Res. 118 6285-6294 (2013). A. Obermann, B. Froment, M. Campillo, E. Larose, T. Planès, B. Valette, J. H. Chen, and Q. Y. Liu, Seismic noise correlations to image structural and mechanical changes associated with the Mw7.9 2008-Wenchuan earthquake, J. Geophys. Res. Solid Earth, 119, 1-14,(2014). Thomas Planès, Eric Larose, Ludovic Margerin, Vincent Rossetto, Christoph Sens-Schoenfelder, Decorrelation and phase-shift of coda waves induced by local changes : Multiple scattering approach and numerical validation, Waves in Random and Complex Media 24, 99-125, (2014)

  20. Petrological and geochemical constraints on the recent increase in explosive activity at Santiaguito volcano, Guatemala

    Science.gov (United States)

    Wallace, Paul A.; Henton De Angelis, Sarah; De Angelis, Silvio; Kendrick, Jackie E.; Hornby, Adrian J.; Lamb, Oliver; von Aulock, Felix W.; Lamur, Anthony; Chigna, Gustavo; Rietbrock, Andreas; Dingwell, Donald B.; Lavallée, Yan

    2017-04-01

    during pre-eruptive storage and ascent. Textural and micro-petrological variations have also been investigated to constrain pre-eruptive conduit conditions, focusing on microlite characteristics that facilitate assessment of crystallisation processes in the shallow conduit and magma ascent rates prior to eruption. Our data is complemented by geophysical observations recorded over the same period, providing further insights into eruption dynamics. This collaborative work not only captures unique observations of the on-going dynamic activity at Santiaguito, but aids in deciphering the complexities associated with transitions in eruptive behaviour for many active silicic volcanoes worldwide. Harris, A.J.L., Rose, W.I., Flynn, L.P., 2003. Temporal trends in lava dome extrusion at Santiaguito 1922 - 2000. Bull. Volcanol. 65, 77-89. Scott, J.A.J., Mather, T.A., Pyle, D.M., Rose, W.I., Chigna, G., 2012. The magmatic plumbing system beneath Santiaguito Volcano, Guatemala. Journal of Volcanology and Geothermal Research 237-238, 54-68.

  1. Monitoring and analysis of nyamulagira volcano activity using modis data: case of the 2011-2012 eruption

    Directory of Open Access Journals (Sweden)

    Bagalwa Montfort

    2015-01-01

    Full Text Available In this paper we analyzed the 2011-2012 eruption of Nyamulagira volcano using MODIS Data. Eruptions have been occurring every 3–4 years throughout the last century. Satellite infrared data, collected by MODIS sensor to estimate pixels thermal anomaly of hot spots were analized, the radiance emitted at 3,959 and 12.02μm for each pixel and the thermal emissions at Nyamulagira feall into three distinct radiating regimes released during the 2011–2012 eruption. Initial activity was detected on 6 November, at 19:55 UTC, with a large thermal anomaly with 28 pixels approximately on the north flank of the volcano. The anomaly was limited to the north flank. The anomaly reached a maximum size of 1188 pixels in January 2012. The size and intensity of the anomaly rapidly diminished to first April 2012 were no more than 2 piixels indicate the end of eruption.

  2. A Sinuous Tumulus over an Active Lava Tube at Klauea Volcano: Evolution, Analogs, and Hazard Forecasts

    Science.gov (United States)

    Orr, Tim R.; Bleacher, Jacob E.; Patrick, Matthew R.; Wooten, Kelly M.

    2015-01-01

    Inflation of narrow tube-fed basaltic lava flows (tens of meters across), such as those confined by topography, can be focused predominantly along the roof of a lava tube. This can lead to the development of an unusually long tumulus, its shape matching the sinuosity of the underlying lava tube. Such a situation occurred during Klauea Volcanos (Hawaii, USA) ongoing East Rift Zone eruption on a lava tube active from July through November 2010. Short-lived breakouts from the tube buried the flanks of the sinuous, ridge-like tumulus, while the tumulus crest, its surface composed of lava formed very early in the flows emplacement history, remained poised above the surrounding younger flows. At least several of these breakouts resulted in irrecoverable uplift of the tube roof. Confined sections of the prehistoric Carrizozo and McCartys flows (New Mexico, USA) display similar sinuous, ridge-like features with comparable surface age relationships. We contend that these distinct features formed in a fashion equivalent to that of the sinuous tumulus that formed at Kilauea in 2010. Moreover, these sinuous tumuli may be analogs for some sinuous ridges evident in orbital images of the Tharsis volcanic province on Mars. The short-lived breakouts from the sinuous tumulus at Kilauea were caused by surges in discharge through the lava tube, in response to cycles of deflation and inflation (DI events) at Kilauea's summit. The correlation between DI events and subsequent breakouts aided in lava flow forecasting. Breakouts from the sinuous tumulus advanced repeatedly toward the sparsely populated Kalapana Gardens subdivision, destroying two homes and threatening others. Hazard assessments, including flow occurrence and advance forecasts, were relayed regularly to the Hawai?i County Civil Defense to aid their lava flow hazard mitigation efforts while this lava tube was active.

  3. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano.

    Science.gov (United States)

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond d'Ars, Jean; Komorowski, Jean-Christophe

    2016-09-15

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 10(6) m(3) to 7 × 10(6) m(3). However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [-0.8;-0.4] × 10(9) kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 10(9) kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir.

  4. Cost effective aero-photogrammetry toys at active volcanoes: On the use of drones, balloons and kites

    Science.gov (United States)

    Walter, Thomas R.

    2014-05-01

    The availability of aerial photographs allows spatial mapping of flows and fractures, generation of digital elevation models and other change detection. Therefore aerial photographs significantly improve our understanding of volcanic processes. The common problem is the lack of available data for most volcanoes, and the lack of systematic and chronologic repeat surveys. This work summarizes the current state of knowledge and technical implementations that currently revolutionize the field of aero-photogrammetry. By the use of unmanned vehicles, such as octocopters, helicopters and small airplanes, photo data can be acquired from almost any place at distances up to kilometres from the operator. Moreover, by the use of helium balloons, kites or their hybrid helikites, near field aero-photographs are obtained. In combination with modern stitching procedures and computer vision algorithms, the positioning of the camera and the digital elevation model of the ground can be extracted, and the active volcano and its eruption cloud be imaged from almost any perspective. This field is increasingly gaining flexibility, as lightweight cameras are available from visible, infrared and other spectral bands. Here example data are provided from volcanoes that are difficult to access by regular airplanes, showing the strengths and the limits of these new aero-photogrammetry toys.

  5. Observations of the Electrical Activity of the Redoubt Volcano in Alaska

    Science.gov (United States)

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

    2009-12-01

    The Mt. Redoubt volcano in Alaska underwent a series of 22 major explosive eruptions over a 2.5 week period between 23 March and 4 April 2009. We were able to deploy a 4-station Lightning Mapping Array (LMA) in advance of the eruptions along a 60 km stretch of the Kenai coastline, 70-80 km east of Redoubt on the opposite side of Cook Inlet, and to monitor and control the station operations remotely via internet connections. The LMA data show that the eruptions produced spectacular lightning, both over and downwind of the volcano, lasting between 20 to 80 minutes depending on the eruption strength. The discharging was essentially continuous during the initial stages of the eruptions and gradually evolved into more discrete and spatially structured discharges displaced from 10 km up to 80 or 90 km away from Redoubt. The discharge rates and VHF radiation signals were comparable to or greater than observed in Great Plains thunderstorms, with discernible but complex 'flashes' occurring at a rate of 2-3 per second in the active stages of eruptions, decaying to about 10-15 per minute of horizontally extensive discrete discharges in later stages. Individual eruptions produced literally thousands of discharges. The approximately linear array of the mapping stations, coupled with their distance from Redoubt and the inability to have a station at a closer distance, has precluded obtaining useful altitude information from the time-of-arrival data. The exception has been lightning at the end of the March 28 eruption as the plume cloud drifted over the northern end of the LMA network; which showed negative charge at 6 km altitude and positive charge between 8 and 9 km altitude, exactly the same as seen in normally electrified thunderstorms. Three of the four stations had been deployed on 50-100m high bluffs overlooking Cook Inlet in an attempt to use sea-surface interference effects to determine altitude, as in our study of the 2006 Augustine eruptions. But only partial

  6. Evolution of magma feeding system in Kumanodake agglutinate activity, Zao Volcano, northeastern Japan

    Science.gov (United States)

    Takebe, Yoshinori; Ban, Masao

    2015-10-01

    The Kumanodake agglutinate of Zao Volcano in northeastern Japan consists of pyroclastic surge layers accumulated during the early part of the newest stage of activity (ca. 33 ka to present). Our petrologic study of this agglutinate based on systematically collected samples aims to reveal the evolution of magma feeding system. To understand the magma evolution, we have examined samples from the agglutinate by using petrologic data including, petrography, analysis of minerals (plagioclase, pyroxene, and olivine), glass compositions, and whole rock major element and trace element (Ba, Sr, Cr, Ni, V, Rb, Zr, Nb, and Y) compositions. Agglutinate are mixed, medium-K, calc-alkaline olv-cpx-opx basaltic andesite (55.2-56.2% SiO2). Results show that the magma feeding system comprised a shallow felsic chamber injected by mafic magma from depth. The felsic magma (59-62% SiO2, 950-990 °C), which was stored at a shallower depth, had orthopyroxene (Mg# = 60-69), clinopyroxene (Mg# = 65-71), and low-An plagioclase (Anca. 58-70). The mafic magma is further divisible into two types: less-differentiated and more-differentiated, designed respectively as an initial mafic magma-1 and a second mafic magma-2. The original mafic magma-1 was olivine (Fo 84) basalt (ca. 48-51% SiO2, 1110-1140 °C). The second mafic magma-2, stored occasionally at 4-6 km depth, was basalt (1070-1110 °C) having Foca. 80 olivine and high-An (Anca. 90) plagioclase phenocrysts. These two magmas mixed (first mixing) to form hybrid mafic magma. The forced injections of the hybrid mafic magmas activated the felsic magma, and these two were mixed (second mixing) shortly before eruptions. The explosivity is inferred to have increased over time because the abundance of large scoria increased. Furthermore, the erupted magma composition became more mafic, which reflects increased percentage of the hybrid mafic magma involved in the second mixing. At the beginning of activity, the mafic magma also acted as a heat

  7. Characteristics of puffing activity revealed by ground-based, thermal infrared imaging: the example of Stromboli Volcano (Italy)

    Science.gov (United States)

    Gaudin, Damien; Taddeucci, Jacopo; Scarlato, Piergiorgio; Harris, Andrew; Bombrun, Maxime; Del Bello, Elisabetta; Ricci, Tullio

    2017-03-01

    Puffing, i.e., the frequent (1 s ca.) release of small (0.1-10 m3), over-pressurized pockets of magmatic gases, is a typical feature of open-conduit basaltic volcanoes worldwide. Despite its non-trivial contribution to the degassing budget of these volcanoes and its recognized role in volcano monitoring, detection and metering tools for puffing are still limited. Taking advantage of the recent developments in high-speed thermal infrared imaging, we developed a specific processing algorithm to detect the emission of individual puffs and measure their duration, size, volume, and apparent temperature at the vent. As a test case, we applied our method at Stromboli Volcano (Italy), studying "snapshots" of 1 min collected in the years 2012, 2013, and 2014 at several vents. In all 3 years, puffing occurred simultaneously at three or more vents with variable features. At the scale of the single vent, a direct relationship links puff temperature and radius, suggesting that the apparent temperature is mostly a function of puff thickness, while the real gas temperature is constant for all puffs. Once released in the atmosphere, puffs dissipate in less than 20 m. On a broader scale, puffing activity is highly variable from vent to vent and year to year, with a link between average frequency, temperature, and volume from 136 puffs per minute, 600 K above ambient temperature, 0.1 m3, and the occasional ejection of pyroclasts to 20 puffs per minute, 3 K above ambient, 20 m3, and no pyroclasts. Frequent, small, hot puffs occur at random intervals, while as the frequency decreases and size increases, an increasingly longer minimum interval between puffs, up to 0.5 s, appears. These less frequent and smaller puffs also display a positive correlation between puff volume and the delay from the previous puff. Our results suggest an important role of shallow bubble coalescence in controlling puffing activity. The smaller and more frequent puffing at "hotter" vents is in agreement with

  8. Behavior of volatiles in arc volcanism : geochemical and petrologic evidence from active volcanoes in Indonesia

    NARCIS (Netherlands)

    Hoog, J.C.M. de

    2001-01-01

    Large amounts of material are recycled along subduction zones by uprising magmas, of which volcanoes are the surface expression. This thesis focuses on the behavior of volatiles elements (S, Cl, H) during these recycling processes. The study area is the Indonesian arc system, which

  9. Evolution of volcanic gas composition during repeated culmination of volcanic activity at Kuchinoerabujima volcano, Japan

    Science.gov (United States)

    Shinohara, H.; Hirabayashi, J.; Nogami, K.; Iguchi, M.

    2011-04-01

    Chemical and isotopic compositions of low to medium temperature fumarolic gasses were measured at various fumaroles of Kuchinoerabujima volcano from 1993 to 2009 by the combination of fumarolic gas sampling and Multi-GAS measurement of volcanic plumes. Repeated culmination of the volcanic activity was observed as contemporaneous occurrence of seismic swarms, summit inflation and demagnetization, almost every two years after 1999. Fumarolic activity also increased parallel with these activities; new fumarolic fields of low-temperature fumaroles at boiling point formed at the southern and western rims of the summit crater in 2003 and intense degassing activity started at medium-temperature fumaroles inside the summit crater in 2008. The low-temperature fumarolic gasses have peculiar composition with high H 2/H 2O, CO/CO 2 and SO 2/H 2S ratios, typical features of high-temperature volcanic gasses, but also with low HCl and total S contents, typical features of low-temperature gasses. These features indicate that the gasses are formed by low-temperature differentiation of high-temperature gasses. Variation of H and O isotopic ratios of the low-temperature gasses indicates that the gasses are formed by isoenthalpic processes of vapor-liquid separation at 100 °C of a high-temperature gas and meteoric water mixture, implying that the high-temperature gas was injected into a shallow aquifer without cooling. Temperatures of the high-temperature gasses were estimated as 550-700 °C based on the equilibrium temperature calculation with considering the low-temperature differentiation. The medium-temperature fumarolic gasses from the summit crater have typical compositions of high-temperature volcanic gasses and are estimated as the source gas of the boiling point fumaroles. The H 2/H 2O and CO 2/S t ratios of the low-temperature fumaroles increased from 2004 to 2009, which is interpreted to be caused by the evolution of thermal structure of a shallow gas storage region of a

  10. On advancing of glaciers due to activity of the Klyuchevskaya Sopka volcano (Kamchatka

    Directory of Open Access Journals (Sweden)

    M. D. Dokukin

    2017-01-01

    Full Text Available New data on continuing advance of the Kamchatka glaciers Erman, Vlodavets, Sopochny, Schmidt, and Bogdanovich were obtained as a result of analysis of aerospace information taken at different times. Glacier Erman advances during the past 70  years (1945–2016. Over the period from 1949 to 2016, its area increased by 4.7 km2 and the length – by 3.3 km (from 18.2 to 21.5 km. The highest speed of advancing had been estimated for the Schmidt glacier, in 2007–2013 it exceeded 100 m/year. We had identified a new isolated glacier between glaciers Erman and Schmidt, named as the Obvalny (the «Avalanche» glacier, since in 1945 this glacier was buried under volcanic-avalanche deposits resulted from the Klyuchevskaya volcano eruption. In 1975–2016, the Obvalny glacier advanced over a distance of about 1700 m. Also, we had found more 30 ice-rock massifs («wandering glaciers» on slopes of the Klyuchevskaya volcano. Their contours looked like drops or tongues, and some of them advanced in the frontal zone. From 2002 to 2016, the «wandering glacier» in the upper reaches of river Glubokaya (eastern sector of the volcano advanced for 740 m (55 m/year. Advancing of glaciers here is a consequence of lateral and terminal eruptions of the Klyuchevskaya volcano in XX and XXI centuries. Erman Glacier, glacier advance, Klyuchevskaya volcano, lateral eruption, space images, volcanic and rock avalanche deposits, «wandering glaciers».

  11. What Are Volcano Hazards?

    Science.gov (United States)

    ... Sheet 002-97 Revised March 2008 What Are Volcano Hazards? Volcanoes give rise to numerous geologic and ... as far as 15 miles from the volcano. Volcano Landslides A landslide or debris avalanche is a ...

  12. Submarine Salt Karst Terrains

    Directory of Open Access Journals (Sweden)

    Nico Augustin

    2016-06-01

    Full Text Available Karst terrains that develop in bodies of rock salt (taken as mainly of halite, NaCl are special not only for developing in one of the most soluble of all rocks, but also for developing in one of the weakest rocks. Salt is so weak that many surface-piercing salt diapirs extrude slow fountains of salt that that gravity spread downslope over deserts on land and over sea floors. Salt fountains in the deserts of Iran are usually so dry that they flow at only a few cm/yr but the few rain storms a decade so soak and weaken them that they surge at dm/day for a few days. We illustrate the only case where the rates at which different parts of one of the many tens of subaerial salt karst terrains in Iran flows downslope constrains the rates at which its subaerial salt karst terrains form. Normal seawater is only 10% saturated in NaCl. It should therefore be sufficiently aggressive to erode karst terrains into exposures of salt on the thousands of known submarine salt extrusions that have flowed or are still flowing over the floors of hundreds of submarine basins worldwide. However, we know of no attempt to constrain the processes that form submarine salt karst terrains on any of these of submarine salt extrusions. As on land, many potential submarine karst terrains are cloaked by clastic and pelagic sediments that are often hundreds of m thick. Nevertheless, detailed geophysical and bathymetric surveys have already mapped likely submarine salt karst terrains in at least the Gulf of Mexico, and the Red Sea. New images of these two areas are offered as clear evidence of submarine salt dissolution due to sinking or rising aggressive fluids. We suggest that repeated 3D surveys of distinctive features (± fixed seismic reflectors of such terrains could measure any downslope salt flow and thus offer an exceptional opportunity to constrain the rates at which submarine salt karst terrains develop. Such rates are of interest to all salt tectonicians and the many

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

    Science.gov (United States)

    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

  14. Transient changes in bacterioplankton communities induced by the submarine volcanic eruption of El Hierro (Canary Islands).

    Science.gov (United States)

    Ferrera, Isabel; Arístegui, Javier; González, José M; Montero, María F; Fraile-Nuez, Eugenio; Gasol, Josep M

    2015-01-01

    The submarine volcanic eruption occurring near El Hierro (Canary Islands) in October 2011 provided a unique opportunity to determine the effects of such events on the microbial populations of the surrounding waters. The birth of a new underwater volcano produced a large plume of vent material detectable from space that led to abrupt changes in the physical-chemical properties of the water column. We combined flow cytometry and 454-pyrosequencing of 16S rRNA gene amplicons (V1-V3 regions for Bacteria and V3-V5 for Archaea) to monitor the area around the volcano through the eruptive and post-eruptive phases (November 2011 to April 2012). Flow cytometric analyses revealed higher abundance and relative activity (expressed as a percentage of high-nucleic acid content cells) of heterotrophic prokaryotes during the eruptive process as compared to post-eruptive stages. Changes observed in populations detectable by flow cytometry were more evident at depths closer to the volcano (~70-200 m), coinciding also with oxygen depletion. Alpha-diversity analyses revealed that species richness (Chao1 index) decreased during the eruptive phase; however, no dramatic changes in community composition were observed. The most abundant taxa during the eruptive phase were similar to those in the post-eruptive stages and to those typically prevalent in oceanic bacterioplankton communities (i.e. the alphaproteobacterial SAR11 group, the Flavobacteriia class of the Bacteroidetes and certain groups of Gammaproteobacteria). Yet, although at low abundance, we also detected the presence of taxa not typically found in bacterioplankton communities such as the Epsilonproteobacteria and members of the candidate division ZB3, particularly during the eruptive stage. These groups are often associated with deep-sea hydrothermal vents or sulfur-rich springs. Both cytometric and sequence analyses showed that once the eruption ceased, evidences of the volcano-induced changes were no longer observed.

  15. Transient changes in bacterioplankton communities induced by the submarine volcanic eruption of El Hierro (Canary Islands.

    Directory of Open Access Journals (Sweden)

    Isabel Ferrera

    Full Text Available The submarine volcanic eruption occurring near El Hierro (Canary Islands in October 2011 provided a unique opportunity to determine the effects of such events on the microbial populations of the surrounding waters. The birth of a new underwater volcano produced a large plume of vent material detectable from space that led to abrupt changes in the physical-chemical properties of the water column. We combined flow cytometry and 454-pyrosequencing of 16S rRNA gene amplicons (V1-V3 regions for Bacteria and V3-V5 for Archaea to monitor the area around the volcano through the eruptive and post-eruptive phases (November 2011 to April 2012. Flow cytometric analyses revealed higher abundance and relative activity (expressed as a percentage of high-nucleic acid content cells of heterotrophic prokaryotes during the eruptive process as compared to post-eruptive stages. Changes observed in populations detectable by flow cytometry were more evident at depths closer to the volcano (~70-200 m, coinciding also with oxygen depletion. Alpha-diversity analyses revealed that species richness (Chao1 index decreased during the eruptive phase; however, no dramatic changes in community composition were observed. The most abundant taxa during the eruptive phase were similar to those in the post-eruptive stages and to those typically prevalent in oceanic bacterioplankton communities (i.e. the alphaproteobacterial SAR11 group, the Flavobacteriia class of the Bacteroidetes and certain groups of Gammaproteobacteria. Yet, although at low abundance, we also detected the presence of taxa not typically found in bacterioplankton communities such as the Epsilonproteobacteria and members of the candidate division ZB3, particularly during the eruptive stage. These groups are often associated with deep-sea hydrothermal vents or sulfur-rich springs. Both cytometric and sequence analyses showed that once the eruption ceased, evidences of the volcano-induced changes were no longer

  16. Aleutian Islands Coastal Resources Inventory and Environmental Sensitivity Maps: VOLCANOS (Volcano Points)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains point locations of active volcanoes as compiled by Motyka et al., 1993. Eighty-nine volcanoes with eruptive phases in the Quaternary are...

  17. Applying Unmanned Airborne Sampling Technology to Active Volcanoes: Successes, Challenges, and Plans

    Science.gov (United States)

    Pieri, D. C.; Diaz, J. A.; Buongiorno, M. F.

    2016-12-01

    Over the last three years, we have conducted in situ sampling of airborne volcanic emissions for the calibration and validation of remote sensing data and derivative ash and gas transport models, as well as for proximal and distal hazard evaluations. We are collaboratively operating currently in three main locales: (a) Costa Rica: Turrialba Volcano; (b) Italy: Vulcano Island and La Sofatara Crater; and (c) the United States: Kilauea Volcano and the Salton Sea Geothermal Zone. During 2014-2016 we systematically deployed fixed wing UAVs and aerostats into the phreato-magmatic plume at Turrialba Volcano in Costa Rica, for time-series 3D SO2 profiles during overpasses of the ASTER radiometer onboard the NASA Terra platform. To date we have completed more than 50 aerostat and/or unmanned fixed and/or rotary wing sampling missions. Preliminary science results have been published by Pieri and Diaz (2015; DyDESS), Diaz et al. (2015; JASMS), and Xi et al. (2016, JVGR). We conducted field measurements of H2S, CO2, and SO2 and other species with INGV quad-copters to lift a UCR Multi-gas sensor into the phreatic gas jet at La Sofatara Crater, Pozzuoli, Italy in October 2014 and at Isole Vulcano in August 2015. At La Solfatara, our results documented 8000ppmv (max) up to 200 ft above the vent, and at Vulcano we noted CO2 concentrations approximately 2x ambient up to 100ft above the main crater. Deployment of the ARC SIERRA-B UAV and Dragon Eye mini-UAVs is now planned for the Salton Sea Geothermal Field in October 2016. We have integrated the UCR 20kg mass-spectrometer into SIERRA-B for flight certification in August 2016. We will also conduct near simultaneous airborne sensor-web observations with Dragon Eye UAVs using targeted electrochemical sensors, including sensors for SO2, H2S, CO2, and NH3, along with simultaneous aerostat (tethered balloon/kite-borne) observations using electrochemical sensors, focused on gas emissions from sub-aerial mud volcano fields. Finally, we

  18. Submarine landslides: advances and challenges

    Science.gov (United States)

    Locat, Jacques; Lee, Homa J.

    2002-01-01

    Due to the recent development of well-integrated surveying techniques of the sea floor, significant improvements were achieved in mapping and describing the morphology and architecture of submarine mass movements. Except for the occurrence of turbidity currents, the aquatic environment (marine and fresh water) experiences the same type of mass failure as that found on land. Submarine mass movements, however, can have run-out distances in excess of 100 km, so their impact on any offshore activity needs to be integrated over a wide area. This great mobility of submarinemass movements is still not very well understood, particularly for cases like the far-reaching debris flows mapped on the Mississippi Fan and the large submarine rock avalanches found around many volcanic islands. A major challenge ahead is the integration of mass movement mechanics in an appropriate evaluation of the hazard so that proper risk assessment methodologies can be developed and implemented for various human activities offshore, including the development of natural resources and the establishment of reliable communication corridors. Key words : submarine slides, hazards, risk assessment, morphology, mobility, tsunami. Le dveloppement rcent de techniques de levs hydrograhiques pour les fonds marins nous a permis d'atteindre une qualit ingale dans la cartographie et la description des glissements sous marins. l'exception des courants de turbidit, on retrouve dans le domaine aquatique les mmes types de mouvements de terrain que sur terre. Par contre, les glissements sous-marins peuvent atteindre des distances excdant 100 km de telle sorte que leur impact sur les activits offshore doit tre pris en compte sur degrandes tendues. La grande mobilit des glissements sous-marins n'est pas encore bien comprise, comme pour le cas des coules dedbris cartographies sur le cne du Mississippi ainsi que pour les grandes avalanches rocheuses sous-marines retrouves au pourtour des les volcaniques. Un dfi majeur

  19. A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity

    Science.gov (United States)

    ALANIS, Paul K. B.; YAMAYA, Yusuke; TAKEUCHI, Akihiro; SASAI, Yoichi; OKADA, Yoshihiro; NAGAO, Toshiyasu

    2013-01-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km × 3 km × 3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano’s activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions. PMID:24126286

  20. Mud Volcanoes Formation And Occurrence

    Science.gov (United States)

    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

  1. Ice-clad volcanoes

    Science.gov (United States)

    Waitt, Richard B.; Edwards, B.R.; Fountain, Andrew G.; Huggel, C.; Carey, Mark; Clague, John J.; Kääb, Andreas

    2015-01-01

    An icy volcano even if called extinct or dormant may be active at depth. Magma creeps up, crystallizes, releases gas. After decades or millennia the pressure from magmatic gas exceeds the resistance of overlying rock and the volcano erupts. Repeated eruptions build a cone that pokes one or two kilometers or more above its surroundings - a point of cool climate supporting glaciers. Ice-clad volcanic peaks ring the northern Pacific and reach south to Chile, New Zealand, and Antarctica. Others punctuate Iceland and Africa (Fig 4.1). To climb is irresistible - if only “because it’s there” in George Mallory’s words. Among the intrepid ascents of icy volcanoes we count Alexander von Humboldt’s attempt on 6270-meter Chimborazo in 1802 and Edward Whymper’s success there 78 years later. By then Cotopaxi steamed to the north.

  2. Geomorphic process fingerprints in submarine canyons

    Science.gov (United States)

    Brothers, Daniel S.; ten Brink, Uri S.; Andrews, Brian D.; Chaytor, Jason D.; Twichell, David C.

    2013-01-01

    Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A) are used to examine linkages between morphological domains and the generation and evolution of submarine sediment flows. For example, canyon reaches of the upper continental slope are characterized by steep, linear and/or convex longitudinal profiles, whereas reaches farther down canyon have distinctly concave longitudinal profiles. The transition between these geomorphic domains is inferred to represent the downslope transformation of debris flows into erosive, canyon-flushing turbidity flows. Over geologic timescales this process appears to leave behind a predictable geomorphic fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may be a proxy for the volume of sediment released during geomorphically significant failures along the upper continental slope. Focused studies of slope-sourced submarine canyons may provide new insights into the relationships between fine-scale canyon morphology and down-canyon changes in sediment flow dynamics.

  3. Spying on volcanoes

    Science.gov (United States)

    Watson, Matthew

    2017-07-01

    Active volcanoes can be incredibly dangerous, especially to those who live nearby, but how do you get close enough to observe one in action? Matthew Watson explains how artificial drones are providing volcanologists with insights that could one day save human lives

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

    Science.gov (United States)

    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

  5. Seismic activity associated with the September 1977 deflation of the Krafla central volcano in NE-Iceland

    Energy Technology Data Exchange (ETDEWEB)

    Brandsdottir, Bryndis; Einarsson, Pall

    1979-01-01

    The September 1977 deflation event in the Krafla caldera was one of a series of such events that has been in progress since December 1975. The operation of portable seismographs in the active region and favorable location of the main seismic activity with respect to the permanent seismograph network in NE-Iceland allow a more detailed study of this deflation event than most of the other events. Continuous volcanic tremor appeared on the local seismographs shortly before 16 h on September 8, 1977. Deflation of the volcano began at the same time. A small basaltic eruption broke out on a 0.9 km long fissure near the northern rim of the caldera at about 18 h. Earthquake activity increased soon after the beginning of the tremor and the first earthquakes were located in the caldera region. The earthquake activity then migrated southwards along the Krafla fault swarm with a speed of about 0.5 m sec{sup -1}, and culminated shortly before midnight with 8 earthquakes larger than magnitude 3 that were located near the Namafjall geothermal area 8 km south of the center of the caldera. Shortly after the earthquake activity migrated into the Namafjall area small amounts of basaltic pumice were erupted through a 1138 m deep drill hole there. Depths of earthquakes were 0-6 km in the northern part of the hypocentral zone and 0-4 in the southern part. The first motion pattern of P-waves suggests dip-slip faulting on steeply dipping fault planes consistent with the extensive normal faulting observed on the surface throughout the epicentral zone. The magnitude-frequency relationship was nonlinear and changed during the earthquake sequence. The seismological data strongly support the interpretation that deflation of the Krafla volcano is associated with horizontal migration of magma from the caldera region and formation of dykes in the Krafla fault swarm.

  6. What can we learn about the history of oceanic shield volcanoes from deep marine sediments? Example from La Reunion volcanoes.

    Science.gov (United States)

    Bachelery, Patrick; Babonneau, Nathalie; Jorry, Stephan; Mazuel, Aude

    2014-05-01

    The discovery in 2006, during the oceanographic survey FOREVER, of large volcaniclastic sedimentary systems off La Réunion Island (western Indian ocean) revealed a new image of the evolution of oceanic shield volcanoes and their dismantling. Marine data obtained from 2006 to 2011 during the oceanographic surveys ERODER 1 to ERODER 4 included bathymetry, acoustic imagery, echosounding profiles, dredging and coring. Six major turbidite systems were mapped and described on the submarine flanks of La Reunion volcanic edifice and the surrounding oceanic plate. The interpretation of sediment cores enable us to characterise the processes of gravity-driven sediment transfer from land to deep sea and also to revisit the history of the volcanoes of La Réunion Island. Turbidite systems constitute a major component of the transfer of volcanic materials to the abyssal plain (Saint-Ange et al., 2011; 2013; Sisavath et al., 2011; 2012; Babonneau et al., 2013). These systems are superimposed on other dismantling processes (slow deformation such as gravity sliding or spreading, and huge landslides causing debris avalanches). Turbidite systems mainly develop in connection with the hydrographic network of the island, and especially at the mouths of large rivers. They show varying degrees of maturity, with canyons incising the submarine slope of the island and feeding depositional areas, channels and lobes extending over 150 km from the coast. The cores collected in turbidite systems show successions of thin and thick turbidites alternating with hemipelagic sedimentation. Sedimentological and stratigraphic analysis of sediment cores yielded a chronology of submarine gravity events. First-order information was obtained on the explosive activity of these volcanoes by identifying tephra layers in the cores (glass shards and pumice). In addition, major events of the volcanic and tectonic history of the island can be identified and dated. In this contribution, we focus most attention on

  7. Catalogue of Icelandic Volcanoes

    Science.gov (United States)

    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

  8. A submarine volcanic eruption leads to a novel microbial habitat.

    Science.gov (United States)

    Danovaro, Roberto; Canals, Miquel; Tangherlini, Michael; Dell'Anno, Antonio; Gambi, Cristina; Lastras, Galderic; Amblas, David; Sanchez-Vidal, Anna; Frigola, Jaime; Calafat, Antoni M; Pedrosa-Pàmies, Rut; Rivera, Jesus; Rayo, Xavier; Corinaldesi, Cinzia

    2017-04-24

    Submarine volcanic eruptions are major catastrophic events that allow investigation of the colonization mechanisms of newly formed seabed. We explored the seafloor after the eruption of the Tagoro submarine volcano off El Hierro Island, Canary Archipelago. Near the summit of the volcanic cone, at about 130 m depth, we found massive mats of long, white filaments that we named Venus's hair. Microscopic and molecular analyses revealed that these filaments are made of bacterial trichomes enveloped within a sheath and colonized by epibiotic bacteria. Metagenomic analyses of the filaments identified a new genus and species of the order Thiotrichales, Thiolava veneris. Venus's hair shows an unprecedented array of metabolic pathways, spanning from the exploitation of organic and inorganic carbon released by volcanic degassing to the uptake of sulfur and nitrogen compounds. This unique metabolic plasticity provides key competitive advantages for the colonization of the new habitat created by the submarine eruption. A specialized and highly diverse food web thrives on the complex three-dimensional habitat formed by these microorganisms, providing evidence that Venus's hair can drive the restart of biological systems after submarine volcanic eruptions.

  9. Volcanoes and the Environment

    Science.gov (United States)

    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

  10. It takes three to tango: 2. Bubble dynamics in basaltic volcanoes and ramifications for modeling normal Strombolian activity

    Science.gov (United States)

    Suckale, Jenny; Hager, Bradford H.; Elkins-Tanton, Linda T.; Nave, Jean-Christophe

    2010-07-01

    This is the second paper of two that examine numerical simulations of buoyancy-driven flow in the presence of large viscosity contrasts. In the first paper, we demonstrated that a combination of three numerical tools, an extended ghost fluid type method, the level set approach, and the extension velocity technique, accurately simulates complex interface dynamics in the presence of large viscosity contrasts. In this paper, we use this threefold numerical method to investigate bubble dynamics in the conduits of basaltic volcanos with a focus on normal Strombolian eruptions. Strombolian type activity, named after the famously episodic eruptions at Stromboli volcano, is characterized by temporally discrete fountains of incandescent clasts. The mildly explosive nature of normal Strombolian activity, as compared to more effusive variants of basaltic volcanism, is related to the presence of dissolved gas in the magma, yielding a complex two-phase flow problem. We present a detailed scaling analysis allowing identification of the pertinent regime for a given flow problem. The dynamic interactions between gas and magma can be classified into three nondimensional regimes on the basis of bubble sizes and magma viscosity. Resolving the fluid dynamics at the scale of individual bubbles is not equally important in all three regimes: As long as bubbles remain small enough to be spherical, their dynamic interactions are limited compared to the rich spectrum of coalescence and breakup processes observed for deformable bubbles, in particular, once inertia ceases to be negligible. One key finding in our simulations is that both large gas bubbles and large conduit-filling gas pockets ("slugs") are prone to dynamic instabilities that lead to their rapid breakup during buoyancy-driven ascent. We provide upper bound estimates for the maximum stable bubble size in a given magmatic system and discuss the ramifications of our results for two commonly used models of normal Strombolian type

  11. Deformation from an Active Crater: Insights into Volcano Dynamics from White Island, New Zeland, using High Resolution SAR data

    Science.gov (United States)

    Hamling, I. J.; Kilgour, G.

    2016-12-01

    Located 48 km offshore, White Island Island is New Zealand's most active volcano with eruptive activity documented for the past 150,000 years. Despite 70% of the volcano being beneath the sea, the main crater is host to a vigorous hydrothermal system and acid crater lake. The island was the scene of one of New Zealand's major volcanic disasters in 1914 when the collapse of the south west corner of the crater wall caused a debris avalanche killing 11 miners. Between 1967 and 2009, 9 long-term deformation events were detected from levelling data within the crater floor. Accompanying these events were a range of activity from small eruptions to more passive degassing. The most recent eruption, on April 27th 2016, removed 15 m of lake floor sediments and much of the crater lake. Here we use high resolution TerraSAR/TanDEM-X SAR data acquired since 2015 to track changes in the lake level in the build up to the eruption and to generate a deformation timeseries. Preceding the eruption, we observe uplift of the crater floor, consistent with the pressurization of the hydrothermal system, and at the same time evidence for continued creep of the south west crater wall which collapsed in 1914. In the months running up to the eruption both the uplift and movement of the crater wall decrease and, at the same time, we see a decrease in the lake level. The eruption deposited a layer of ash across the crater floor which we assess using a combination of field measurements, coherence loss and changes in the radar amplitude. Following the eruption, as the lake began to refill, we see renewed motion of the crater wall accompanied by localised subsidence around the crater lake. We suggest that changes to the hydrothermal system and crater lake are sufficient to alter the pore pressure within the volcanic edifice promoting failure of the crater wall.

  12. Submarine geothermal resources

    Science.gov (United States)

    Williams, D.L.

    1976-01-01

    Approximately 20% of the earth's heat loss (or 2 ?? 1012 cal/s) is released through 1% of the earth's surface area and takes the form of hydrothermal discharge from young (Pleistocene or younger) rocks adjacent to active seafloor-spreading centers and submarine volcanic areas. This amount is roughly equivalent to man's present gross energy consumption rate. A sub-seafloor geothermal reservoir, to be exploitable under future economic conditions, will have to be hot, porous, permeable, large, shallow, and near an energy-deficient, populated land mass. Furthermore, the energy must be recoverable using technology achievable at a competitive cost and numerous environmental, legal and institutional problems will have to be overcome. The highest-temperature reservoirs should be found adjacent to the zones of the seafloor extension or volcanism that are subject to high sedimentation rates. The relatively impermeable sediments reduce hydrothermal-discharge flow rates, forcing the heat to be either conducted away or released by high-temperature fluids, both of which lead to reservoir temperatures that can exceed 300??C. There is evidence that the oceanic crust is quite permeable and porous and that it was amenable to deep (3-5 km) penetration by seawater at least some time in the early stages of its evolution. Most of the heat escapes far from land, but there are notable exceptions. For example, in parts of the Gulf of California, thermal gradients in the bottom sediments exceed 1??C/m. In the coastal areas of the Gulf of California, where electricity and fresh water are at a premium, this potential resource lies in shallow water (< 200 m) and within sight of land. Other interesting areas include the Sea of Japan, the Sea of Okhotsk and the Andaman Sea along the margins of the western Pacific, the Tyrrhenian Sea west of Italy, and the southern California borderland and west flank of the Juan de Fuca Ridge off the west coast of the United States. Many questions remain to be

  13. High resolution deformation measurements at active volcanoes: a new remote sensing technology

    Science.gov (United States)

    Hort, M. K.; Scharff, L.; Gerst, A.; Meier, K.; Falk, S.; Peters, G.; Ripepe, M.

    2013-12-01

    It is known from observations at different volcanoes using ULP seismic observations that the volcanic edifice deforms slightly prior to an eruption. It can be expected that immediately prior to an eruption the largest deformation should occur in the vicinity of the vent. However, placing instruments at the vent is impossible as they will be destroyed during an eruption. Here we present new, high temporal resolution (up to 300Hz) deformation measurement that utilizes the phase information of a frequency modulated Doppler radar system. We decompose the Doppler signal into two parts, one part which allows us to measure speeds significantly above 0.5m/s (i.e. the movement of volcanic ash and clasts). The other part utilizes the slow phase changes of the signal reflected from non-moving objects, i.e. the volcanic edifice. This signal is used to measure very slow and longer term deformations, which are the main subject of this study. The method has been tested measuring the displacement of high rise buildings during strong winds. It can be shown that displacements down to 50 μm can be resolved without a problem. We apply this method to different data sets collected at Stromboli volcano, Italy, as well as Santiaguito volcano, Guatemala. At Stromboli we observed the NE crater once in 2008 and once in 2011. During both campaigns we observe on average a displacement between 1 and 5mm before different eruptions. This displacement can be interpreted as a widening of the conduit prior to an eruption. In a couple of cases even an oscillatory movement is observed with frequencies of about 0.5Hz. Finite element modeling of the rise of a pressurized slug indicates that deformations at the crater rim on the order of a 1mm or less are certainly reasonable. In the case of Santiaguito volcano prior to an eruption we observe a pre eruptive displacement 5-15mm and after the end of an eruption a displacement of up to 1m before the next eruption occurs. This can be interpreted as in

  14. Seismic Activity Related to the 2002-2003 Mt. Etna Volcano Eruption (Italy): Fault Plane Solutions and Stress Tensor Computation

    Science.gov (United States)

    Barberi, G.; Cammarata, L.; Cocina, O.; Maiolino, V.; Musumeci, C.; Privitera, E.

    2003-04-01

    Late on the night of October 26, 2002, a bi-lateral eruption started on both the eastern and the southeastern flanks of Mt. Etna. The opening of the eruptive fracture system on the NE sector and the reactivation of the 2001 fracture system, on the S sector, were accompanied by a strong seismic swarm recorded between October 26 and 28 and by sharp increase of volcanic tremor amplitude. After this initial phase, on October 29 another seismogenetic zone became active in the SE sector of the volcano. At present (January 2003) the eruption is still in evolution. During the whole period a total of 862 earthquakes (Md≫1) was recorded by the local permanent seismic network run by INGV - Sezione di Catania. The maximum magnitude observed was Md=4.4. We focus our attention on 55 earthquakes with magnitude Md≫ 3.0. The dataset consists of accurate digital pickings of P- and S-phases including first-motion polarities. Firstly earthquakes were located using a 1D velocity model (Hirn et alii, 1991), then events were relocated by using two different 3D velocity models (Aloisi et alii, 2002; Patane et alii, 2002). Results indicate that most of earthquakes are located to the east of the Summit Craters and to northeast of them. Fault plane solutions (FPS) obtained show prevalent strike-slip rupture mechanisms. The suitable FPSs were considered for the application of Gephart and Forsyth`s algorithm in order to evaluate seismic stress field characteristics. Taking into account the preliminary results we propose a kinematic model of the eastern flank eastward movement in response of the intrusion processes in the central part of the volcano. References Aloisi M., Cocina O., Neri G., Orecchio B., Privitera E. (2002). Seismic tomography of the crust underneath the Etna volcano, Sicily. Physics of the Earth and Planetary Interiors 4154, pp. 1-17 Hirn A., Nercessian A., Sapin M., Ferrucci F., Wittlinger G. (1991). Seismic heterogeneity of Mt. Etna: structure and activity. Geophys. J

  15. Monitoring of the nuclear submarine Komsomolets

    Energy Technology Data Exchange (ETDEWEB)

    Heldal, Hilde E.; Flo, Janita K.; Liebig, Penny L. [Institute of Marine Research, P. O. Box 1870 Nordnes, N-5817 Bergen (Norway); Gaefvert, Torbjoern; Rudjord, Anne Liv [Norwegian Radiation Protection Authority, P.O. Box 55, N-1332 Oesteraas (Norway); Gwynn, Justin P. [Norwegian Radiation Protection Authority, The Fram Centre, N-9296 Tromsoe (Norway)

    2014-07-01

    The Soviet nuclear submarine Komsomolets sank on the 7 April 1989, 180 km southwest of Bear Island in the Norwegian Sea to a depth of about 1655 m. The submarine contains one nuclear reactor containing long-lived radionuclides such as cesium-137 ({sup 137}Cs) along with other fission and activation products, in addition to 2 mixed uranium/plutonium nuclear warheads containing weapons grade plutonium. Although several model studies have shown that a radioactive leakage from Komsomolets will have insignificant impact on fish and other marine organisms, there are still public concerns about the condition of the submarine and the potential for radioactive leakage. In order to document the contamination levels and to meet public concerns, monitoring of radioactive contamination in the area adjacent to the submarine has been ongoing since 1993. Samples of bottom seawater and sediments have been collected annually by the Institute of Marine Research (IMR) and have been analysed for {sup 137}Cs and plutonium-239,240 ({sup 239,240}Pu). So far, activity concentrations in the samples have been comparable to levels found in other samples from the Norwegian and Barents Seas. During sampling from R/V 'G. O. Sars' in April 2013, an area of about 1 km{sup 2} of the seabed around Komsomolets was mapped to precisely locate the submarine using a Kongsberg EM302 multibeam echo sounder, a Simrad EK60 single beam echo sounder and an Olex 3D bottom-mapping system. For sediment sampling, a Simrad MST342 mini-transponder was attached to a Smoegen box corer to allow for precise positioning of the corer. With the aid of the Kongsberg HiPAP (High Precision Acoustic Positioning) system, 4 box cores were collected around the submarine at a distance of 10 to 20 m. In addition, one box core was collected from a reference station about 100 m upstream of the submarine. Surface sediments and sediment cores were collected from the box cores taken at each sampling location. Sediment cores

  16. Changes in seabed morphology, mud temperature and free gas venting at the Håkon Mosby mud volcano, offshore northern Norway, over the time period 2003-2006

    Science.gov (United States)

    Foucher, Jean-Paul; Dupré, Stéphanie; Scalabrin, Carla; Feseker, Tomas; Harmegnies, François; Nouzé, Hervé

    2010-06-01

    The Håkon Mosby mud volcano is a 1.5-km-diameter geological structure located on the Southwest Barents Sea slope at a water depth of 1,270 m. High-definition seabed mapping of the mud volcano has been carried out in 2003 and 2006. A comparative analysis of the bathymetry and backscatter maps produced from the two surveys shows subtle morphological changes over the entire crater of the mud volcano, interpreted to be the consequence of mud eruption events. Mud temperature measurements point to a persistently warm mud at shallow depth in the crater. This is explained by upward fluid advection, rather than conductive cooling of mud flows. The small-scale spatial variability in the temperature distribution may be related to mud outflows or changes in the fluid flow regime. Furthermore, the locations of free gas venting observed in 2006 were found to differ from those of 2003. Our observations of overall similar topographic profiles across the mud volcano in 2003 and 2006 suggest that eruption events would have been modest. Nevertheless, the data bring evidence of significant change in activity even over short time intervals of only 3 years. This may be a characteristic shared by other submarine mud volcanoes, notably those considered to be in a quiescent stage.

  17. Volcano seismology

    Science.gov (United States)

    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

  18. Preliminary volcano-hazard assessment for Kanaga Volcano, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Miller, Thomas P.; Nye, Christopher J.

    2002-01-01

    Kanaga Volcano is a steep-sided, symmetrical, cone-shaped, 1307 meter high, andesitic stratovolcano on the north end of Kanaga Island (51°55’ N latitude, 177°10’ W longitude) in the western Aleutian Islands of Alaska. Kanaga Island is an elongated, low-relief (except for the volcano) island, located about 35 kilometers west of the community of Adak on Adak Island and is part of the Andreanof Islands Group of islands. Kanaga Volcano is one of the 41 historically active volcanoes in Alaska and has erupted numerous times in the past 11,000 years, including at least 10 eruptions in the past 250 years (Miller and others, 1998). The most recent eruption occurred in 1993-95 and caused minor ash fall on Adak Island and produced blocky aa lava flows that reached the sea on the northwest and west sides of the volcano (Neal and others, 1995). The summit of the volcano is characterized by a small, circular crater about 200 meters in diameter and 50-70 meters deep. Several active fumaroles are present in the crater and around the crater rim. The flanking slopes of the volcano are steep (20-30 degrees) and consist mainly of blocky, linear to spoonshaped lava flows that formed during eruptions of late Holocene age (about the past 3,000 years). The modern cone sits within a circular caldera structure that formed by large-scale collapse of a preexisting volcano. Evidence for eruptions of this preexisting volcano mainly consists of lava flows exposed along Kanaton Ridge, indicating that this former volcanic center was predominantly effusive in character. In winter (October-April), Kanaga Volcano may be covered by substantial amounts of snow that would be a source of water for lahars (volcanic mudflows). In summer, much of the snowpack melts, leaving only a patchy distribution of snow on the volcano. Glacier ice is not present on the volcano or on other parts of Kanaga Island. Kanaga Island is uninhabited and is part of the Alaska Maritime National Wildlife Refuge, managed by

  19. Asymmetric Volcano Trend in Oxygen Reduction Activity of Pt and Non-Pt Catalysts: In Situ Identification of the Site-Blocking Effect.

    Science.gov (United States)

    Li, Jingkun; Alsudairi, Amell; Ma, Zi-Feng; Mukerjee, Sanjeev; Jia, Qingying

    2017-02-01

    Proper understanding of the major limitations of current catalysts for oxygen reduction reaction (ORR) is essential for further advancement. Herein by studying representative Pt and non-Pt ORR catalysts with a wide range of redox potential (E redox ) via combined electrochemical, theoretical, and in situ spectroscopic methods, we demonstrate that the role of the site-blocking effect in limiting the ORR varies drastically depending on the E redox of active sites; and the intrinsic activity of active sites with low E redox have been markedly underestimated owing to the overlook of this effect. Accordingly, we establish a general asymmetric volcano trend in the ORR activity: the ORR of the catalysts on the overly high E redox side of the volcano is limited by the intrinsic activity; whereas the ORR of the catalysts on the low E redox side is limited by either the site-blocking effect and/or intrinsic activity depending on the E redox .

  20. Evidence of persistent seismo-volcanic activity at Marsili seamount

    Directory of Open Access Journals (Sweden)

    Antonino D'Alessandro

    2012-06-01

    Full Text Available The Marsili submarine volcano is the largest European volcano, and it can be considered as the key to our understanding of the dynamics of the spreading and back-arc lithosphere formation in the Tyrrhenian sector [Marani et al. 2004, and references therein]. Despite its size, it is very difficult to monitor due to its geographical position [D'Alessandro et al. 2011], and it still remains little known. In 2006, the Centro Nazionale Terremoti (National Earthquake Centre of the Istituto Nazionale di Geofisica e Vulcanologia (INGV deployed a broadband ocean-bottom seismometer with hydrophone (OBS/H [Mangano et al. 2011] on the flat top of Marsili volcano, at a depth of ca. 790 m. In only nine days, the instrument recorded ca. 800 seismo-volcanic events [D'Alessandro et al. 2009]. This revealed the intense seismo-volcanic activity of Marsili volcano for the first time. […] 

  1. Depth profiles of resistivity and spectral IP for active modern submarine hydrothermal deposits: a case study from the Iheya North Knoll and the Iheya Minor Ridge in Okinawa Trough, Japan

    Science.gov (United States)

    Komori, Shogo; Masaki, Yuka; Tanikawa, Wataru; Torimoto, Junji; Ohta, Yusuke; Makio, Masato; Maeda, Lena; Ishibashi, Jun-ichiro; Nozaki, Tatsuo; Tadai, Osamu; Kumagai, Hidenori

    2017-08-01

    Submarine hydrothermal deposits are one of the promising seafloor mineral resources, because they can store a large amount of metallic minerals as sulfides. The present study focuses on the electrical properties of active modern submarine hydrothermal deposits, in order to provide constraints on the interpretation of electrical structures obtained from marine electromagnetic surveys. Measurements of resistivity and spectral induced polarization (IP) were made using drillcore samples taken from the Iheya North Knoll and the Iheya Minor Ridge in Okinawa Trough, Japan. These hydrothermal sediments are dominantly composed of disseminated sulfides, with minor amounts of massive sulfide rocks. The depth profiles of resistivity and spectral IP properties were successfully revealed to correspond well to layer-by-layer lithological features. Comparison with other physical properties and occurrence of constituent minerals showed that resistivity is essentially sensitive to the connectivity of interstitial fluids, rather than by sulfide and clay content. This suggests that, in active modern submarine hydrothermal systems, not only typical massive sulfide rocks but also high-temperature hydrothermal fluids could be imaged as low-resistivity anomalies in seabed surveys. The spectral IP signature was shown to be sensitive to the presence or absence of sulfide minerals, and total chargeability is positively correlated with sulfide mineral abundance. In addition, the massive sulfide rock exhibits the distinctive IP feature that the phase steadily increases with a decrease of frequency. These results show the effective usage of IP for developing and improving marine IP exploration techniques.[Figure not available: see fulltext.

  2. Ovariectomy influences the circadian rhythm of locomotor activity and the photic phase shifts in the volcano mouse.

    Science.gov (United States)

    Juárez-Tapia, Cinthia; Miranda-Anaya, Manuel

    2017-12-01

    Recently, the relationship between the circadian system and female reproduction has been of great interest; ovarian hormones can modify the amount and distribution of daily activity differently in rodent species. The volcano mouse Neotomodon alstoni is a species in which it is possible to study the circadian rhythm of locomotion, and it offers comparative information about the influence of ovaries on the circadian system. In this study, we used infrared crossings to compare free movement in intact and sham-operated or ovariectomized mice. We analyzed behavioral and endocrine changes related to the estrous cycle and locomotor circadian rhythm in free-running mice and photic phase shifting. Evidence shows that intact mice present a scalloped pattern of daily activity during the estrous cycle. In constant darkness, the ovariectomy reduces the total amount of activity, shortens the free-running circadian period of locomotion and increases photic phase shifts during the early subjective night. During entrainment, the ovariectomized mice increased the amplitude of total activity during the scotophase, and delay the time of activity onset. These results suggest that ovarian hormones in N. alstoni modulate the circadian rhythm of locomotor activity in a species-specific manner. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Miocene Current-Modified Submarine Fans

    Science.gov (United States)

    Arce Perez, L. E.; Snedden, J.; Fisher, W. L.

    2016-12-01

    In the southwestern Gulf of Mexico, new and newly reprocessed seismic data has revealed a series of large bedforms, with set thicknesses of 130 to 250 meters. These exhibit hummocky, oblique and shingled to parallel seismic clinoform reflections. This seismic package has a paleowater depth of 450 meters. Those shingled seismic reflections in offshore east Mexico are interpreted as contourite drift deposits. These Miocene-age contourites may be related to strong ocean bottom currents that modified submarine fans and transported sediment to the north. Those contourites were identified on older seismic data, but are better imaged and interpreted on this new data. Plans are to map out and investigate the origin and extent of fans and contourites that extends over a large area of the Gulf of Mexico. In the Early Miocene several submarine fans systems were formed by the sediment input related to orogenic activity in Mexico. Submarine fan development persisted into the Middle Miocene due to continued uplift and erosion of the Mexican landmass. Initial, contourites are small and close proximity to the deep-water fan. In the Late Miocene time, contourite drift field reached its maximum extent in the Mexican deepwater area, anchored on its southern end by a submarine mound. This mounded submarine fan is located in the offshore northeast Veracruz and can be linked to increased uplift and erosion of the Trans-Mexican volcanic belt. In the Miocene-Pliocene, the large contourite drift begins to diminish in size and scale and is moribund by the Pliocene, with establishment of oceanic circulation similar to the present day. This research is important to understand more about the Gulf of Mexico and also for the Miocene timeframe that is a key phase in the earth's history. The role of the change in bottom water flow during progressive closure of the equatorial seaway separating North and South America will also be investigated.

  4. Exercise Aboard Attack Submarines: Rationale and New Options

    Science.gov (United States)

    2004-08-18

    experience loss of physical fitness while underway. Bennett and co-workers (2) noted a 7% reduction of maximal oxygen consumption in non-exercising...Inc. designed and built a comprehensive resistance exercise device to help counteract muscle deconditioning during long term space flights (the SX... Physical activity aboard nuclear submarines as measured by pedometry. Groton: Naval Submarine Medical Research Laboratory, Report 1053, 1985, p. 12

  5. Shiveluch and Klyuchevskaya Volcanoes

    Science.gov (United States)

    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.

  6. Eruption of a deep-sea mud volcano triggers rapid sediment movement

    Science.gov (United States)

    Feseker, Tomas; Boetius, Antje; Wenzhöfer, Frank; Blandin, Jerome; Olu, Karine; Yoerger, Dana R.; Camilli, Richard; German, Christopher R.; de Beer, Dirk

    2014-01-01

    Submarine mud volcanoes are important sources of methane to the water column. However, the temporal variability of their mud and methane emissions is unknown. Methane emissions were previously proposed to result from a dynamic equilibrium between upward migration and consumption at the seabed by methane-consuming microbes. Here we show non-steady-state situations of vigorous mud movement that are revealed through variations in fluid flow, seabed temperature and seafloor bathymetry. Time series data for pressure, temperature, pH and seafloor photography were collected over 431 days using a benthic observatory at the active Håkon Mosby Mud Volcano. We documented 25 pulses of hot subsurface fluids, accompanied by eruptions that changed the landscape of the mud volcano. Four major events triggered rapid sediment uplift of more than a metre in height, substantial lateral flow of muds at average velocities of 0.4 m per day, and significant emissions of methane and CO2 from the seafloor. PMID:25384354

  7. Noble gases in submarine pillow basalt glasses from Loihi and Kilauea, Hawaii: A solar component in the Earth

    Science.gov (United States)

    Honda, M.; McDougall, I.; Patterson, D.B.; Doulgeris, A.; Clague, D.A.

    1993-01-01

    Noble gas elemental and isotopic abundances have been analysed in twenty-two samples of basaltic glass dredged from the submarine flanks of two currently active Hawaiian volcanoes, Loihi Seamount and Kilauea. Neon isotopic ratios are enriched in 20Ne and 21Ne by as much as 16% with respect to atmospheric ratios. All the Hawaiian basalt glass samples show relatively high 3He 4He ratios. The high 20Ne 22Ne values in some of the Hawaiian samples, together with correlations between neon and helium systematics, suggest the presence of a solar component in the source regions of the Hawaiian mantle plume. The solar hypothesis for the Earth's primordial noble gas composition can account for helium and neon isotopic ratios observed in basaltic glasses from both plume and spreading systems, in fluids in continental hydrothermal systems, in CO2 well gases, and in ancient diamonds. These results provide new insights into the origin and evolution of the Earth's atmosphere. ?? 1993.

  8. [Medical-physiological characteristics of combat training of nuclear-power submarine crews].

    Science.gov (United States)

    Dovgusha, V V; Myznikov, I L; Shalabodov, S A; Bumaĭ, O K

    2009-10-01

    The article presents an observe of general questions of peculiarities of military-professional activity of submarine staff These questions are defining value in ideology of medical supply of submarine troops of NAVY in now-days conditions. The article also presents the statistics of morbidity in long termed sails for last forty years, it's dynamics by different categories of sail staff, on different stages of combat training activity in dependence of perioditation of work cycle of submarine staff The authors have examined modern condition of medical supply of submarines; have presented statistics of quality indexes of health of submarine staff The authors have formed main problems of medical supply of submarines and have proposed ways of their solving on modern stage.

  9. Reconstructing 800 years of historical eruptive activity at Popocatépetl Volcano, Mexico

    Science.gov (United States)

    Martin-Del Pozzo, Ana Lillian; Rodríguez, Alan; Portocarrero, Jorge

    2016-03-01

    Pictorial and written documents spanning 800 years were analyzed for information about historical eruptions at Popocatépetl volcano. These documents were prepared by several indigenous groups as well as by the Spanish conquistadors and missionaries during their military campaigns and long-term evangelization and colonization and later on, by Indian nobles and Spanish historians. Pre-Columbian drawings show flames coming out of Popocatépetl's crater while later descriptions from the Spanish colonial period in Mexico (1521 to 1821) refer to ash emission and ballistics, lahars, and some pumice falls, similar to what were depicted in the thirteenth to sixteenth century drawings. Graphic information from the pre-Columbian codices, colonial maps, and paintings referring to the eruptions were correlated with historical accounts and religious chronicles, thereby leading to the reconstruction of a more detailed sequence of eruptive events. From such information, it was possible for us to prepare ash distribution maps for the 1540, 1592, and 1664 eruptions. Most of the known historical eruptions seem to be similar to those that have been occurring at Popocatépetl since 1994, indicating the importance of ash emission and crater dome formation throughout its recent eruptive history. The strongest eruptions occurred in 1510, 1519, 1540, 1580, 1664, and 2001; these produced widespread ash falls that affected both populated and rural areas. Duration of eruptive episodes during the past 800 years were estimated to have ranged from less than a year to more than 30 years, separated by repose periods ranging between 7 and over 100 years.

  10. Borehole observations of fluid flow from South Chamorro Seamount, an active serpentinite mud volcano in the Mariana forearc

    Science.gov (United States)

    Wheat, C. Geoffrey; Fryer, Patricia; Fisher, Andrew T.; Hulme, Samuel; Jannasch, Hans; Mottl, Michael J.; Becker, Keir

    2008-03-01

    A sealed borehole observatory (CORK) was deployed on South Chamorro Seamount, an active serpentinite mud volcano in the Mariana forearc to explore subduction-related processes on a non-accretionary, convergent plate margin. Formation fluid was overpressured relative to ambient hydrostatic conditions. Fluid flowed from the borehole at ~ 0.2 L/s when the observatory was opened to recover instruments 2 yr after it was installed. The chemical composition of the formation fluid is similar to that extrapolated from trends in pore water data collected during Ocean Drilling Program Leg 195 when the observatory was established. Reduced sulfur is present in this highly-alkaline (pH 12.4) formation fluid, indicative of microbial activity at or below the depth of the screened casing, 149-202 m below the seafloor. Discharge from the open borehole continued for 37 days, until the observatory was resealed. This discharge requires significant permeability at depth (> 6 × 10 - 14 m 2). Zones of high permeability may be associated with the formation of headwall scarps, consistent with numerous slumps on the southeastern flank of the seamount, and likely shape a geochemical environment suitable for an active microbial community.

  11. Submarine Arc Volcanism in the Southern Mariana Arc: Results of Recent ROV studies

    Science.gov (United States)

    Nichols, A. R.; Tamura, Y.; Stern, R. J.; Embley, R. W.; Hein, J. R.; Jordan, E.; Ribeiro, J. M.; Sica, N.; Kohut, E. J.; Whattam, S. A.; Hirahara, Y.; Senda, R.; Nunokawa, A.

    2009-12-01

    The submarine Diamante cross-arc volcanoes (~16°N) and the Sarigan-Zealandia Bank Multi-Volcano Complex (SZBMVC; ~16°45’N), north and south, respectively, of Anatahan Island in the southern Mariana Arc, were studied during several dives in June 2009 using the ROV Hyper-Dolphin, cruise NT09-08 (R/V Natsushima); neither has been studied in detail before. The data collected provide a new perspective on how the subduction factory operates to complement previous studies on other cross-arc volcanic chains in the Izu-Bonin-Mariana Arc. The Diamante complex consists of three major edifices, two cones (West and Central Diamante) and a more complex caldera-like edifice at the volcanic front (East Diamante). West and Central Diamante are basaltic volcanoes but East Diamante has a more complex history. Our studies indicate initial construction of a basaltic volcano. Magmatic evolution led to a violent caldera-forming and quieter dome-building events. Post-caldera quiescence allowed a carbonate platform to grow, now preserved on the eastern caldera wall. Felsic magma or hot rock provides a heat source for an active hydrothermal field associated with felsic domes in the caldera, which NOAA investigators discovered in 2004. A new type of hydrothermal deposit was discovered in the hydrothermal field, consisting of large sulfide-sulfate mounds topped by bulbous constructions of low-temperature Fe and Mn oxides. Vents on the mounds were observed to emit shimmering water. The SZBMVC consists of six closely spaced edifices whose loci are aligned along two parallel trends, one along the volcanic front (Zealandia Bank, Sarigan and South Sarigan), and one about 15 km west towards the rear-arc (Northwest Zealandia, West Zealandia and West Sarigan). Zealandia Bank dives revealed that, as with East Diamante, initial activity was basaltic and became more evolved with time. The western half of Zealandia Bank is dominated by felsic lavas centered on a small (~2 km diameter) caldera and

  12. Cardiometabolic Health in Submariners Returning from a 3-Month Patrol

    Directory of Open Access Journals (Sweden)

    Heath G. Gasier

    2016-02-01

    Full Text Available Confined space, limited exercise equipment, rotating shift work and reduced sleep may affect cardiometabolic health in submariners. To test this hypothesis, 53 male U.S. Submariners (20–39 years were studied before and after a 3-month routine submarine patrol. Measures included anthropometrics, dietary and physical activity, biomarkers of cardiometabolic health, energy and appetite regulation, and inflammation. Before deployment, 62% of submariners had a body fat % (BF% ≥ 25% (obesity, and of this group, 30% met the criteria for metabolic syndrome. In obese volunteers, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR, leptin, the leptin/adiponectin ratio, and pro-inflammatory chemokines growth-related oncogene and macrophage-derived chemokine were significantly higher compared to non-obese submariners. Following the patrol, a significant mean reduction in body mass (5% and fat-mass (11% occurred in the obese group as a result of reduced energy intake (~2000 kJ during the patrol; and, independent of group, modest improvements in serum lipids and a mean reduction in interferon γ-induced protein 10 and monocyte chemotactic protein 1 were observed. Since 43% of the submariners remained obese, and 18% continued to meet the criteria for metabolic syndrome following the patrol, the magnitude of weight loss was insufficient to completely abolish metabolic dysfunction. Submergence up to 3-months, however, does not appear to be the cause of obesity, which is similar to that of the general population.

  13. Catalogue of Icelandic Volcanoes

    Science.gov (United States)

    Ilyinskaya, Evgenia; Larsen, Gudrún; Gudmundsson, Magnús T.; Vogfjörd, Kristin; Jonsson, Trausti; Oddsson, Björn; Reynisson, Vidir; Pagneux, Emmanuel; Barsotti, Sara; Karlsdóttir, Sigrún; Bergsveinsson, Sölvi; Oddsdóttir, Thorarna

    2017-04-01

    The Catalogue of Icelandic Volcanoes (CIV) is a newly developed open-access web resource (http://icelandicvolcanoes.is) intended to serve as an official source of information about volcanoes in Iceland for the public and decision makers. CIV contains text and graphic information on all 32 active volcanic systems in Iceland, as well as real-time data from monitoring systems in a format that enables non-specialists to understand the volcanic activity status. The CIV data portal contains scientific data on all eruptions since Eyjafjallajökull 2010 and is an unprecedented endeavour in making volcanological data open and easy to access. CIV forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the European Union funded effort FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite. The supersite concept implies integration of space and ground based observations for improved monitoring and evaluation of volcanic hazards, and open data policy. This work is a collaboration of the Icelandic Meteorological Office, 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.

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

    Science.gov (United States)

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

    2010-01-01

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

  15. Radon and its decay product activities in the magmatic area and the adjacent volcano-sedimentary Intrasudetic Basin

    Directory of Open Access Journals (Sweden)

    D. Tchorz

    2007-06-01

    Full Text Available In the magmatic area of Sudetes covering the Karkonosze granite and adjacent volcano-sedimentary Intrasudetic Basin a study of atmospheric radon activity was performed by means of SSNTD Kodak LR-115. The study was completed by gamma spectrometric survey of eU and eTh determined by gamma activity of radon decay products 214Bi and 208Tl respectively. In the case of the western part of the Karkonosze granite area the radon decay products activity in the granitic basement was found to be as high as 343 Bq/kg for 214Bi and 496 Bq/kg for 208Tl respectively. Atmospheric radon content measured by means of Kodak LR115 track detector at the height of 1.5 m was found as high as 70 Bq/m3 in the regions, where no mining activities took place. However in the eastern part of the granitic massif in the proximity of abandoned uranium mine atmospheric radon content was found to be 6000 Bq/m3. In the case of sedimentary basin where sedimentary sequence of Carboniferous rocks has been penetrated by younger gases and fluids of volcanic origin uranium mineralization developed. The region known from its CO2 outburst during coal mining activity is characterized by good ventilation of the uranium enriched geological basement resulting in increased atmospheric radon activity being in average 72 Bq/m3. In the vicinity of coal mine tailing an increase up to 125 Bq/m3 can be observed. Seasonal variations of atmospheric radon content are influenced in agricultural areas by cyclic cultivation works (plough on soils of increased uranium content and in the case of post-industrial brownfields varying rates of radon exhalation from tailings due to different meteorological conditions.

  16. "Mediterranean volcanoes vs. chain volcanoes in the Carpathians"

    Science.gov (United States)

    Chivarean, Radu

    2017-04-01

    Volcanoes have always represent an attractive subject for students. Europe has a small number of volcanoes and Romania has none active ones. The curricula is poor in the study of volcanoes. We want to make a parallel between the Mediterranean active volcanoes and the old extinct ones in the Oriental Carpathians. We made an comparison of the two regions in what concerns their genesis, space and time distribution, the specific relief and the impact in the landscape, consequences of their activities, etc… The most of the Mediterranean volcanoes are in Italy, in the peninsula in Napoli's area - Vezuviu, Campi Flegrei, Puzzoli, volcanic islands in Tirenian Sea - Ischia, Aeolian Islands, Sicily - Etna and Pantelleria Island. Santorini is located in Aegean Sea - Greece. Between Sicily and Tunisia there are 13 underwater volcanoes. The island called Vulcano, it has an active volcano, and it is the origin of the word. Every volcano in the world is named after this island, just north of Sicily. Vulcano is the southernmost of the 7 main Aeolian Islands, all volcanic in origin, which together form a small island arc. The cause of the volcanoes appears to be a combination of an old subduction event and tectonic fault lines. They can be considered as the origin of the science of volcanology. The volcanism of the Carpathian region is part of the extensive volcanic activity in the Mediterranean and surrounding regions. The Carpathian Neogene/Quaternary volcanic arc is naturally subdivided into six geographically distinct segments: Oas, Gutai, Tibles, Calimani, Gurghiu and Harghita. It is located roughly between the Carpathian thrust-and-fold arc to the east and the Transylvanian Basin to the west. It formed as a result of the convergence between two plate fragments, the Transylvanian micro-plate and the Eurasian plate. Volcanic edifices are typical medium-sized andesitic composite volcanoes, some of them attaining the caldera stage, complicated by submittal or peripheral domes

  17. Submarine mass wasting processes along slopes influenced by long-term tectonic erosion: The Middle America Trench

    Science.gov (United States)

    Harders, R.; Ranero, C. R.; Weinrebe, W.

    2011-12-01

    We have studied submarine land-sliding using a seafloor topography and side-scan sonar data along the continental slope of the Middle America Trench. This subduction zone is dominated by tectonic erosion. Studies during the last few decades have shown mass wasting structures at submarine slopes around the world's continental margins, hot-spot volcanic islands, and volcanic island arcs. At Atlantic margins slides initiate at low slope angles and appear triggered by high sediment accumulation rates. At volcanic islands large-scale land-sliding is caused by volcano sector collapse. At subduction zones with accretionary prisms, land-sliding seems associated to contractional tectonics and fluid seepage. Submarine mass movements at subduction zones dominated by tectonic erosion are comparatively limited. However, tectonic erosion is active in about 50% of the world subduction zones. Distinct failures have been studied at slopes in Peru, Costa Rica, Nicaragua and New Zealand but extensive surveys have not been obtained. We present a comprehensive data sets on seafloor mapping on a subduction zone dominated by tectonic erosion. The data covers much of the Middle America Trench (MAT) from the Mexico-Guatemala border to Costa Rica - Panama border. The goal of this contribution is to evaluate how long-term tectonics caused by subduction erosion preconditions the continental slope structure to modulate the generation of land-sliding. We show that changes in subduction erosion processes, interacting with the local topography of the subducting plate correlate to variations in the type and distribution of failures along the slope of the region.

  18. Submarine terrace limestones from the continental slope off Saurashtra-Bombay: Evidence of Late Quaternary neotectonic activity

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Veerayya, M.

    m depth terrace was at intertidal depths at about 12,000 years BP. The eustatic sea-level, however, was at - 90 m at 12,000 years BP. This disparity suggests neotectonic activity and subsidence by about 40 m on the Saurashtra-Bombay region some time...

  19. SCICEX: Submarine Arctic Science Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration among the operational Navy, research agencies, and the marine research community...

  20. The Submarine, 1776-1918

    National Research Council Canada - National Science Library

    Uhlig, Frank

    2004-01-01

    When, on 11 April 1900, the U.S. Navy thought the Holland, named for its designer, that little submarine joined a fleet consisting of two armored cruisers, six monitors, seven first and second-class battleships, and seventeen each...

  1. First Use of an Autonomous Glider for Exploring Submarine Volcanism in the SW Pacific

    Science.gov (United States)

    Matsumoto, H.; Embley, R. W.; Haxel, J. H.; Dziak, R. P.; Bohnenstiehl, D. R.; Stalin, S.; Meinig, C.

    2010-12-01

    A 1000-m Slocum glider® (Teledyne Webb Research Corporation) with CTD, turbidity, and hydrophone sensors was operated for two days in the Northeast Lau Basin. The survey was conducted near West Mata Volcano, where in November of 2008 the NOAA PMEL Vents program observed an active eruption at its 1207 m summit—the deepest submarine activity ever before witnessed. Our goal was to use the glider as a forensic tool to search for other nearby eruption sites with onboard sensors that detect the chemical and hydroacoustic signatures associated with the volcanic and hydrothermal plumes. The glider was launched approximately 40 km to the west of West Mata. It flew toward West Mata and was recovered near the summit of the volcano after repeating 13 yos during a 41-hour mission. Although the recordings were affected by mechanical noise from the glider’s rudder, the data demonstrate that the system can detect the wide-band noises (>1 kHz) associated with submarine volcanic and intense hydrothermal activity. The glider recorded complex acoustic amplitudes due to the multiple raypaths from West Mata as well as temporal variations in the volcano’s rate of activity, and demonstrated that these geologic processes contribute to the region’s high ambient noise levels. With the exception of the deployment and recovery, the mission was managed entirely by the shore teams in PMEL (Seattle, WA) and OSU labs (Newport, OR), ~5000 miles away without an engineer onboard. The dive cycle of the 950-m dives was ~3.5 hours and the average speed was ~0.27 cm/s. The CTD data were downloaded at every surface cycle and appeared to be of high quality. However we found that the sensitivity of the Wetlabs ECO flntu turbidity sensor was not adequate for the detection of volcanic plumes. The mission demonstrated PMEL’s ability to use autonomous gliders to monitor a variety of environmental parameters including ambient sound levels, temperature, salinity and turbidity for the purpose of finding

  2. Volcanic and Hydrothermal Activity of the North Su Volcano: New Insights from Repeated Bathymetric Surveys and ROV Observations

    Science.gov (United States)

    Thal, J.; Bach, W.; Tivey, M.; Yoerger, D.

    2013-12-01

    Bathymetric data from cruises in 2002, 2006, and 2011 were combined and compared to determine the evolution of volcanic activity, seafloor structures, erosional features and to identify and document the distribution of hydrothermal vents on North Su volcano, SuSu Knolls, eastern Manus Basin (Papua New Guinea). Geologic mapping based on ROV observations from 2006 (WHOI Jason-2) and 2011 (MARUM Quest-4000) combined with repeated bathymetric surveys from 2002 and 2011 are used to identify morphologic features on the slopes of North Su and to track temporal changes. ROV MARUM Quest-4000 bathymetry was used to develop a 10 m grid of the top of North Su to precisely depict recent changes. In 2006, the south slope of North Su was steeply sloped and featured numerous white smoker vents discharging acid sulfate waters. These vents were covered by several tens of meters of sand- to gravel-sized volcanic material in 2011. The growth of this new cone changed the bathymetry of the south flank of North Su up to ~50 m and emplaced ~0.014 km3 of clastic volcanic material. This material is primarily comprised of fractured altered dacite and massive fresh dacite as well as crystals of opx, cpx, olivine and plagioclase. There is no evidence for pyroclastic fragmentation, so we hypothesize that the fragmentation is likely related to hydrothermal explosions. Hydrothermal activity varies over a short (~50 m) lateral distance from 'flashing' black smokers to acidic white smoker vents. Within 2 weeks of observation time in 2011, the white smoker vents varied markedly in activity suggesting a highly episodic hydrothermal system. Based on ROV video recordings, we identified steeply sloping (up to 30°) slopes exposing pillars and walls of hydrothermal cemented volcaniclastic material representing former fluid upflow zones. These features show that hydrothermal activity has increased slope stability as hydrothermal cementation has prevented slope collapse. Additionally, in some places

  3. A preliminary survey of the broadband seismic wavefield at Puu Oo, the active vent of Kilauea volcano, Hawaii

    Directory of Open Access Journals (Sweden)

    P. Okubo

    1996-06-01

    Full Text Available The seismic wavefield near an active volcanic vent consists of superimposed signals in a wide range of frequency bands from sources inside and outside the volcano. To characterize the broadband wavefield near Puu Oo, we deployed a profile of three three-component broadband sensors in a 200 m long line about 1.5 km WSW of the active vent. During this period, Puu Oo maintained a constant, but very low level of activity. The digital data logger recorded the wavefield continuously in the frequency band between 0.01 and 40 Hz between June 25 and July 9, 1994. At the same time, local wind conditions along with air temperature and pressure were monitored by a portable digital weather station. On the basis of characteristic elements, such as waveform, spatial coherence between stations, particle motion and power spectra, the wavefield can be divided into three bands. The dominant signals in the frequency band between 0.01 and 0.1 Hz are not coherent among the stations. Their ground velocities correlate with the wind speed. The signals in the 0.1 to 0.5 Hz band are coherent across the profile and most probably represent a superposition of volcanic tremor and microseisms from the Pacific Ocean. Much of the energy above 0.5 Hz can be attributed to activity at the vent. Power spectra from recordings of the transverse components show complex peaks between 0.5 and 3 Hz which vary in amplitude due to site effects and distance. On the other hand, power spectra calculated from the radial components show a clearly periodic pattern of peaks at 1 Hz intervals for some time segments. A further remarkable feature of the power spectra is that they are highly stationary.

  4. Hawaiian submarine manganese-iron oxide crusts - A dating tool?

    Science.gov (United States)

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

    2004-01-01

    Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae

  5. Introduction to the special issue on submarine geohazard records and potential seafloor instability

    Directory of Open Access Journals (Sweden)

    Song-Chuen Chen Jia-Jyun Dong

    2018-01-01

    Full Text Available Submarine landslides frequently occur in passive continental margins or active margins (Hampton et al. 1996; Wynn et al. 2000; Mienert et al. 2002; Korup et al. 2007; Twichell et al. 2009; Cukur et al. 2016. Submarine landslides have been studied extensively not only for scientific research but also for submarine geohazards. Submarine landslides could jeopardize marine infrastructures, such as offshore drilling platforms or submarine telecommunication cables, and could even trigger disastrous tsunamis (Bondevik et al. 2005; Harbitz et al. 2006; Hornbach et al. 2007, 2008; Hsu et al. 2008; Su et al. 2012; Tappin et al. 2014; Li et al. 2015. For instance, one disastrous tsunami hitting the coastal area of southwestern Taiwan in 1781 or 1782 was reported (Chen 1830; Hsu 1983; the tsunami event was probably generated by submarine landslides in the offshore area of southwestern Taiwan (Li et al. 2015. Moreover, several submarine landslides triggered by the 2006 Pingtung earthquake have induced turbidity currents off southwest Taiwan and destroyed about 14 submarine telecommunication cables off SW Taiwan (Hsu et al. 2008. The area of southwest Taiwan currently has a dense population (more than 3 million people in total, one deep-water Kaohsiung Port, several tanks of liquefied natural gas and a nuclear power plant on the coast (Fig. 1. Numerous submarine telecommunication cables exist off SW Taiwan. If a considerable tsunami event would hit again the costal area of SW Taiwan, the damage could very serious. Likewise, there are two nuclear power plants on the coast of northern Taiwan (Fig. 2, and the population in northern Taiwan has more than 10 million people. Submarine telecommunication cables also exist off northern Taiwan. In any case, it is important to understand the status of seafloor stability in the offshore areas of SW and NE Taiwan. For that, this special issue of submarine geohazard records and potential seafloor instability is aimed to

  6. Alaska volcanoes guidebook for teachers

    Science.gov (United States)

    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

  7. Lifespans of Cascade Arc volcanoes

    Science.gov (United States)

    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.

  8. A sinuous tumulus over an active lava tube at Kīlauea Volcano: Evolution, analogs, and hazard forecasts

    Science.gov (United States)

    Orr, Tim R.; Bleacher, Jacob E.; Patrick, Matthew R.; Wooten, Kelly M.

    2015-01-01

    Inflation of narrow tube-fed basaltic lava flows (tens of meters across), such as those confined by topography, can be focused predominantly along the roof of a lava tube. This can lead to the development of an unusually long tumulus, its shape matching the sinuosity of the underlying lava tube. Such a situation occurred during Kīlauea Volcano's (Hawai'i, USA) ongoing East Rift Zone eruption on a lava tube active from July through November 2010. Short-lived breakouts from the tube buried the flanks of the sinuous, ridge-like tumulus, while the tumulus crest, its surface composed of lava formed very early in the flow's emplacement history, remained poised above the surrounding younger flows. At least several of these breakouts resulted in irrecoverable uplift of the tube roof. Confined sections of the prehistoric Carrizozo and McCartys flows (New Mexico, USA) display similar sinuous, ridge-like features with comparable surface age relationships. We contend that these distinct features formed in a fashion equivalent to that of the sinuous tumulus that formed at Kīlauea in 2010. Moreover, these sinuous tumuli may be analogs for some sinuous ridges evident in orbital images of the Tharsis volcanic province on Mars. The short-lived breakouts from the sinuous tumulus at Kīlauea were caused by surges in discharge through the lava tube, in response to cycles of deflation and inflation (DI events) at Kīlauea's summit. The correlation between DI events and subsequent breakouts aided in lava flow forecasting. Breakouts from the sinuous tumulus advanced repeatedly toward the sparsely populated Kalapana Gardens subdivision, destroying two homes and threatening others. Hazard assessments, including flow occurrence and advance forecasts, were relayed regularly to the Hawai'i County Civil Defense to aid their lava flow hazard mitigation efforts while this lava tube was active.

  9. A sinuous tumulus over an active lava tube at Kīlauea Volcano: evolution, analogs, and hazard forecasts

    Science.gov (United States)

    Orr, Tim R.; Bleacher, Jacob E.; Patrick, Matthew R.; Wooten, Kelly M.

    2015-01-01

    Inflation of narrow tube-fed basaltic lava flows (tens of meters across), such as those confined by topography, can be focused predominantly along the roof of a lava tube. This can lead to the development of an unusually long tumulus, its shape matching the sinuosity of the underlying lava tube. Such a situation occurred during Kīlauea Volcano's (Hawai'i, USA) ongoing East Rift Zone eruption on a lava tube active from July through November 2010. Short-lived breakouts from the tube buried the flanks of the sinuous, ridge-like tumulus, while the tumulus crest, its surface composed of lava formed very early in the flow's emplacement history, remained poised above the surrounding younger flows. At least several of these breakouts resulted in irrecoverable uplift of the tube roof. Confined sections of the prehistoric Carrizozo and McCartys flows (New Mexico, USA) display similar sinuous, ridge-like features with comparable surface age relationships. We contend that these distinct features formed in a fashion equivalent to that of the sinuous tumulus that formed at Kīlauea in 2010. Moreover, these sinuous tumuli may be analogs for some sinuous ridges evident in orbital images of the Tharsis volcanic province on Mars. The short-lived breakouts from the sinuous tumulus at Kīlauea were caused by surges in discharge through the lava tube, in response to cycles of deflation and inflation (DI events) at Kīlauea's summit. The correlation between DI events and subsequent breakouts aided in lava flow forecasting. Breakouts from the sinuous tumulus advanced repeatedly toward the sparsely populated Kalapana Gardens subdivision, destroying two homes and threatening others. Hazard assessments, including flow occurrence and advance forecasts, were relayed regularly to the Hawai'i County Civil Defense to aid their lava flow hazard mitigation efforts while this lava tube was active.

  10. Assessing submarine gas hydrate at active seeps on the Hikurangi Margin, New Zealand, using controlled source electromagnetic data with constraints from seismic, geochemistry, and heatflow data

    Science.gov (United States)

    Schwalenberg, K.; Haeckel, M.; Pecher, I. A.; Toulmin, S. J.; Hamdan, L. J.; Netzeband, G.; Wood, W.; Poort, J.; Jegen, M. D.; Coffin, R. B.

    2009-12-01

    Electrical resistivity is one of the key properties useful for evaluating submarine gas hydrate deposits. Gas hydrates are electrically insulating in contrast to the conductive pore fluid. Where they form in sufficient quantities the bulk resistivity of the sub-seafloor is elevated. CSEM data were collected in 2007 as part of the German - International “New Vents” project on R/V Sonne, cruise SO191, at three target areas on the Hikurangi subduction margin, New Zealand. The margin is characterized by widespread bottom simulating reflectors (BSR), seep structures, and active methane and fluid venting indicating the potential for gas hydrate formation. Opouawe Bank is one of the ridge and basin systems on the accretionary wedge and is located off the Wairarapa coast at water depths of 1000-1100 m. The first observed seep sites (North Tower, South Tower, Pukeko, Takahe, and Tui) were identified from individual gas flares in hydro-acoustic data and video observations during voyages on R/V Tangaroa. Seismic reflection data collected during SO191 subsequently identified more than 25 new seep structures. Two intersecting CSEM profiles have been surveyed across North Tower, South Tower, and Takahe. 1-D inversion of the data reveals anomalously high resistivities at North Tower and South Tower, moderately elevated resistivities at Takahe, and normal background resistivities away from the seeps. The high resistivities are attributed to gas hydrate layers at intermediate depths beneath the seeps. At South Tower the hydrate concentration could be possibly as much as 25% of the total sediment volume within a 50m thick layer. This conforms with geochemical pore water analyses which show a trend of increased methane flux towards South Tower. At Takahe, gas pockets and patchy gas hydrate, as well as sediment heterogeneities and carbonates, or temperature driven upward fluid flow indicated by the observed higher heat flow at this site may explain the resistivity pattern

  11. Insights into the 3D architecture of an active caldera ring-fault at Tendürek volcano through modeling of geodetic data

    KAUST Repository

    Vasyura-Bathke, Hannes

    2015-04-28

    The three-dimensional assessment of ring-fault geometries and kinematics at active caldera volcanoes is typically limited by sparse field, geodetic or seismological data, or by only partial ring-fault rupture or slip. Here we use a novel combination of spatially dense InSAR time-series data, numerical models and sand-box experiments to determine the three-dimensional geometry and kinematics of a sub-surface ring-fault at Tendürek volcano in Turkey. The InSAR data reveal that the area within the ring-fault not only subsides, but also shows substantial westward-directed lateral movement. The models and experiments explain this as a consequence of a ‘sliding-trapdoor’ ring-fault architecture that is mostly composed of outward-inclined reverse segments, most markedly so on the volcano\\'s western flanks but includes inward-inclined normal segments on its eastern flanks. Furthermore, the model ring-fault exhibits dextral and sinistral strike-slip components that are roughly bilaterally distributed onto its northern and southern segments, respectively. Our more complex numerical model describes the deformation at Tendürek better than an analytical solution for a single rectangular dislocation in a half-space. Comparison to ring-faults defined at Glen Coe, Fernandina and Bárðarbunga calderas suggests that ‘sliding-trapdoor’ ring-fault geometries may be common in nature and should therefore be considered in geological and geophysical interpretations of ring-faults at different scales worldwide.

  12. Submarine Information Organization and Prioritization and Submarine Officer of the Deck Experience

    Science.gov (United States)

    2004-07-12

    The Submarine Review, 58-64. Shobe, K. (2002, May). Information organization and modeling of the submarine officer of the deck and sonar operator...Technical Report 01Oct00 - 31Sep02 SUBMARINE INFORMATION ORGANIZATION AND PRIORITIZATION AND SUBMARINE OFFICER OF THE DECK EXPERIENCE 51001 1) Katharine K

  13. Global Volcano Locations Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC maintains a database of over 1,500 volcano locations obtained from the Smithsonian Institution Global Volcanism Program, Volcanoes of the World publication. The...

  14. Geological Implications on the Different Products of Submarine Volcanism in Sangihe Waters : View from the Rov (Remotely Operated Vehicles)

    Science.gov (United States)

    Priyadi, B.; Basuki, N.; Abidin, H.; Permana, H.; Handayani, L.; Wirasantosa, S.; Nganro, N.; Djamaluddin, R.; Ch. Kusuma, L.; Ratna Setyawidati, N.; Makarim, S.; Solihudin, T.

    2010-12-01

    Index Satal 2010, a joint marine research of Indonesia - USA, was realized in June-August 2010 to explore the deep sea of the Sangihe - Talaud Waters of Indonesia. This research was conducted by RV Baruna Jaya-4 and RV Okeanos Explorer of NOAA. Beside conducting multi beam imagery, RV Okeanos Explorer produced photos and video of the selected sites through high definition cameras mounted on an ROV operated from onboard RV Okeanos Explorer. The following discussion were based on ROV observation concerning the occurrence of volcanic products in the dive sites. Two submarine volcanoes (Naung and Kawio Barat), indicate various textures of submarine volcanic products from which magmatic composition and eruption types can be inferred. Lava is mostly observed around Kawio Barat and reflecting slightly coarse grained, thick and less structured, and in some spots flow textures could be observed especially in rough morphology. The overlying lavas show finer grain size with relatively shinny surface and darker color and supposedly having less contents of silica as it forms pillow and sheeting joint structures. The rock composition is presumably basaltic and is related with the subduction systems of the Sangihe arc. The coarser lavas might be more andesitic in composition, hence they are originated from the more differentiated magma chamber. This phenomenon indicates a change of magmatic composition from more differentiated magma to the less differentiated one. Geologically, this observation may indicate new formation of magma that may be related with the increasing intensity of subduction activity. Volcanic products around Naung are observed as pyroclastic covers on basaltic lavas. Pyroclastics present as lapilli deposit in light to dark brown colors forming stratification of 2 cm to 30 cm thick and unconsolidated clastic materials. The occurrence of pebble-size fragments of igneous rocks associated with pyroclastics indicate a phreatic to phreato-magmatic explosions of the

  15. Magmatic sill intrusions beneath El Hierro Island following the 2011-2012 submarine eruption

    Science.gov (United States)

    Benito-Saz, María Á.; Sigmundsson, Freysteinn; Parks, Michelle M.; García-Cañada, Laura; Domínguez Cerdeña, Itahiza

    2016-04-01

    El Hierro, the most southwestern island of Canary Islands, Spain, is a volcano rising from around 3600 m above the ocean floor and up to of 1500 m above sea level. A submarine eruption occurred off the coast of El Hierro in 2011-2012, which was the only confirmed eruption in the last ~ 600 years. Activity continued after the end of the eruption with six magmatic intrusions occurring between 2012-2014. Each of these intrusions was characterized by hundreds of earthquakes and 3-19 centimeters of observed ground deformation. Ground displacements at ten continuous GPS sites were initially inverted to determine the optimal source parameters (location, geometry, volume/pressure change) that best define these intrusions from a geodetic point of view. Each intrusive period appears to be associated with the formation of a separate sill, with inferred volumes between 0.02 - 0.3 km3. SAR images from the Canadian RADARSAT-2 satellite and the Italian Space Agency COSMO-SkyMed constellation have been used to produce high-resolution detailed maps of line-of-sight displacements for each of these intrusions. These data have been combined with the continuous GPS observations and a joint inversion undertaken to gain further constraints on the optimal source parameters for each of these separate intrusive events. The recorded activity helps to understand how an oceanic intraplate volcanic island grows through repeated sill intrusions; well documented by seismic, GPS and InSAR observations in the case of the El Hierro activity.

  16. Constancy and variability of Strombolian eruptive activity: long-term analysis of infrared surveillance videos from Stromboli Volcano

    Science.gov (United States)

    Taddeucci, J.; Palladino, D. M.; Bernini, D.; Sottili, G.; Andronico, D.; Cristaldi, A.

    2012-04-01

    Persistent Strombolian activity characterizes open-conduit volcanoes worldwide. Among these, Stromboli (Italy) is one of the best monitored by permanent networks that include visible and infrared cameras. Continuous surveillance videos from the INGV archive allow us to parameterize the dynamics of explosive events in the period 2005-2009. Here we focus on three consecutive days per each year, by analyzing a total of 4275 explosive events from the different active vents. Via image analysis of the video frames, we obtained the time lapse among consecutive events, and duration and geometrical parameters (maximum height, width, and ejection angle) of individual jets. Long-term average values of the above parameters quantitatively define the activity baseline, as follows: inter-event time lapse 5 minutes (standard deviation 5 minutes); jet duration 15 s (5 s); jet height 70 m (24 m); jet width 33 m (10 m); jet axis at angle of 3° (16°) to the vertical. Significant deviations from these baseline values are observed over different (minute to year) time-scales, e.g.: peak jet durations and heights may reach up to 120 s and 251 m, respectively. The analysis of the mutual relationships among the eruptive parameters, and their temporal variation patterns at the different vents, provide a statistically based groundwork to define the dynamics of Strombolian activity. In this regard, a higher aspect ratio (height over width) of the jet seems to reflect increasing depth of the bubble burst beneath the magma free surface in the conduit, to be compared with seismic- and acoustic-derived information. Also, the remarkable constancy of jet angles at specific vents, notwithstanding the occurrence of a significant collapse of the whole crater area during the 2007 eruptive crisis, reveals self-similar resumption of the branching, shallow conduit system and provides insights into its connection to the feeder dike. The robust statistically based definition of the Stromboli behaviour can

  17. Enhancing Submarine Operational Relevance: A Leadership Challenge

    National Research Council Canada - National Science Library

    Daigle, Jr, Michael J

    2008-01-01

    .... This vision of submarine operations must change. As the military continues to shift to operations focused on joint capabilities, the submarine force must break from the closed, protective, and risk averse culture of its past and push forward...

  18. Magmatic degassing, lava dome extrusion, and explosions from Mount Cleveland volcano, Alaska, 2011-2015: Insight into the continuous nature of volcanic activity over multi-year timescales

    Science.gov (United States)

    Werner, Cynthia; Kern, Christoph; Coppola, Diego; Lyons, John J.; Kelly, Peter J.; Wallace, Kristi L.; Schneider, David J.; Wessels, Rick L.

    2017-05-01

    Mount Cleveland volcano (1730 m) is one of the most active volcanoes in the Aleutian arc, Alaska, but heightened activity is rarely accompanied by geophysical signals, which makes interpretation of the activity difficult. In this study, we combine volcanic gas emissions measured for the first time in August 2015 with longer-term measurements of thermal output and lava extrusion rates between 2011 and 2015 calculated from MODIS satellite data with the aim to develop a better understanding of the nature of volcanic activity at Mount Cleveland. Degassing measurements were made in the month following two explosive events (21 July and 7 August 2015) and during a period of new dome growth in the summit crater. SO2 emission rates ranged from 400 to 860 t d- 1 and CO2/SO2 ratios were budget, suggesting a continued presence of shallow magma in the upper conduit, likely driven by convection. Axisymmetric dome morphology and occasional drain back of lava into the conduit suggests low-viscosity magmas drive volcanism at Mount Cleveland. It follows also that only small overpressures can be maintained given the small domes and fluid magmas, which is consistent with the low explosivity of most of Mount Cleveland's eruptions. Changes between phases of dome growth and explosive activity are somewhat unpredictable and likely result from plugs that are related to the dome obtaining a critical dimension, or from small variations in the magma ascent rate that lead to crystallization-induced blockages in the upper conduit, thereby reducing the ability of magma to degas. We suggest the small magma volumes, slow ascent rates, and low magma viscosity lead to the overall lack of anomalous geophysical signals prior to eruptions, and that more continuous volcanic degassing measurements might lead to more successful eruption forecasting at this continuously-active open-vent volcano.

  19. Dynamic of the volcanic activity of La Soufrière volcano (Guadeloupe, Lesser Antillles): Evidence for shallow fluid seismic sources

    Science.gov (United States)

    Ucciani, G.; Beauducel, F.; Bouin, M. P.; Nercessian, A.

    2015-12-01

    La Soufrière is one of the many hazardous volcanoes in the inner arc of Lesser Antilles. Located South of Basse-Terre island, it is the only active volcano of the Guadeloupe archipelago. Since the last significant magmatic eruption in 1535 AD, the activity has been exculsively phreatic. Since 1992 and the abrupt renewal of seismic and fumarollic activities, the Guadeloupe Volcanological and Seismological Observatory (OVSG-IPGP) has recorded a progressive increasing of seismicity and degassing that led scientists and authorities to set the alert level ``Vigilance'' and hold it until today. According to the recent geophysical, geochemical and geological studies, the current volcanic activity of la Soufrière volcano seems to be exclusively associated to the hydrothermal system, while the link with seismic activity is still poorly studied. In this context of possible pre-eruptive unrest, we investigated the spatial and temporal variations of the seismicity recorded between 1981 and 2013. From a consistent seismological framework coupling spectral, statistical, signal processing, clustering, and inverse problems methods, we demonstrate that this seismicity is largely generated by shallow hydrothermal fluid sources located in a complex plumbing system. Spatial variations of Vp/Vs ratio and B-value in seismogenic structures allow us to document three main seismic zones associated to : (1) migration of magmatic gas, (2) the storage and mixing of underground water and gas and (3) the shallow migration of hydrothermal fluids in high fractured and heterogeneous system. Waveform analysis revealed a low number of significant families consistent with fracturing process, and the temporal evolution of multiplet activities highlighted several variations associated with surface manifestations and brutal dynamic changes after major local tectonic earthquakes of Les Saintes (21 November 2004, Mw=6.3), its main aftershock (14 February 2005, Mw=5.7) and the last major earthquake of la

  20. Volcanic-ash hazard to aviation during the 2003-2004 eruptive activity of Anatahan volcano, Commonwealth of the Northern Mariana Islands

    Science.gov (United States)

    Guffanti, M.; Ewert, J.W.; Gallina, G.M.; Bluth, G.J.S.; Swanson, G.L.

    2005-01-01

    Within the Commonwealth of the Northern Mariana Islands (CNMI), Anatahan is one of nine active subaerial volcanoes that pose hazards to major air-traffic routes from airborne volcanic ash. The 2003-2004 eruptive activity of Anatahan volcano affected the region's aviation operations for 3 days in May 2003. On the first day of the eruption (10 May 2003), two international flights from Saipan to Japan were cancelled, and several flights implemented ash-avoidance procedures. On 13 May 2003, a high-altitude flight through volcanic gas was reported, with no perceptible damage to the aircraft. TOMS and MODIS analysis of satellite data strongly suggests that no significant ash and only minor amounts of SO2 were involved in the incident, consistent with crew observations. On 23 May 2003, airport operations were disrupted when tropical-cyclone winds dispersed ash to the south, dusting Saipan with light ashfall and causing flight cancellations there and at Guam 320 km south of the volcano. Operational (near-real-time) monitoring of ash clouds produced by Anatahan has been conducted since the first day of the eruption on 10 May 2003 by the Washington Volcanic Ash Advisory Center (VAAC). The VAAC was among the first groups outside of the immediate area of the volcano to detect and report on the unexpected eruption of Anatahan. After being contacted about an unusual cloud by National Weather Service forecasters in Guam at 1235 UTC on 10 May 2003, the VAAC analyzed GOES 9 images, confirming Anatahan as the likely source of an ash cloud and estimating that the eruption began at about 0730 UTC. The VAAC issued its first Volcanic Ash Advisory for Anatahan at 1300 UTC on 10 May 2003 more than 5 h after the start of the eruption, the delay reflecting the difficulty of detecting and confirming a surprise eruption at a remote volcano with no in situ real-time geophysical monitoring. The initial eruption plume reached 10.7-13.4 km (35,000-44,000 ft), well into jet cruise altitudes

  1. Reconstruction of the eruptive activity on the NE sector of Stromboli volcano: timing of flank eruptions since 15 ka

    NARCIS (Netherlands)

    Calvari, S.; Branca, S.; Corsaro, R.A.; De Beni, E.; Miraglia, L.; Norini, G.; Wijbrans, J.R.; Boschi, E.

    2011-01-01

    A multidisciplinary geological and compositional investigation allowed us to reconstruct the occurrence of flank eruptions on the lower NE flank of Stromboli volcano since 15 ka. The oldest flank eruption recognised is Roisa, which occurred at ~15 ka during the Vancori period, and has transitional

  2. Boron geochemistry of mud volcano products and their significance for global B cycling

    Science.gov (United States)

    Deyhle, A.; Kopf, A.

    2003-04-01

    Mud volcanism is a global phenomenon in mostly convergent margin settings, whose nature has long been subject to scientific investigation. However, only recently its significance has been unravelled by quantitative studies in well-investigated submarine environments, like large accretionary complexes. The fluid flux through active mud volcanoes has been estimated to exceed that of the frontal accretionary prism (Kopf et al. 2001, EPSL 189), and may have done so in earlier earth history. We report results from a systematic B geochemical study of pore fluids, muds and clasts of onshore and offshore mud volcanoes all over the world (Kopf and Deyhle, 2002, Chem. Geol., 192). When tied into results from hydrothermal geochemical experiments in the laboratory (You et al. 1996, EPSL 140), the B geochemistry proofs to be a powerful tracer to estimate the depth of fluid and mud mobilization below ground. Boron adsorbed to clay minerals is preferably donated to the fluid when either tectonic stress (vertical and/or lateral compaction) or temperature increase. Here, we report variations in B content and B isotopes in mud volcano deposits as a result of different history of the material prior to extrusion. Results reflect the regional geology of the study areas, ranging from dewatering of undercompacted marine sediments in accretionary prisms (Barbados, Makran, Mediterranean Sea) to diagenetic reactions in mud volcanoes of orogenic belts (Malaysia, Pakistan, Georgia, Taman Peninsula, Western Alps). Boron shows maximum enrichment in the fluid phase (owing to desorption in the mud) when faulting roots deepest and deformation is strongest. Mud domes juxtaposing out-of-sequence faults in the Caucasus orogenic wedge show mud B contents 8x marine sediment and fluid B contents up to 25x seawater. Deep-seated, B-rich fluids liquefy clay-bearing strata to facilitate mud extrusion, allowing the clay to re-adsorb B in the process. B isotopic composition of the mud decreases with incipient

  3. The volcano-sedimentary succession of Upper Permian in Wuli area, central Qinghai-Tibetan Plateau: Sedimentology, geochemistry and paleogeography

    Science.gov (United States)

    Liu, Shengqian; Jiang, Zaixing; Gao, Yi

    2017-04-01

    Detailed observations on cores and thin sections well documented a volcano-sedimentary succession from Well TK2, which is located in Wuli area, central Qinghai-Tibetan Plateau. The TK2 volcano-sedimentary succession reflects an active sedimentary-tectonic setting in the north margin of North Qiangtang-Chamdo terrane in the late Permian epoch. Based on the observation and recognition on lithology and mineralogy, the components of TK2 succession are mainly volcanic and volcaniclastic rocks and four main lithofacies are recognized, including massive volcanic lithofacies (LF1), pyroclastic tuff lithofacies (LF2), tuffaceous sandstone lithofacies (LF3) and mudstone lithofacies (LF4). LF1 is characterized by felsic components, massive structure and porphyrotopic structure with local flow structure, which indicates submarine intrusive domes or extrusion-fed lavas that formed by magma ascents via faults or dykes. Meanwhile, its eruption style may reflect a relative high pressure compensation level (PCL) that mainly determined by water depth, which implies a deep-water environment. LF2 is composed of volcanic lapilli or ash and featured with massive structure, parallel bedding and various deformed laminations including convolve structure, slide deformation, ball-and-pillow structure, etc.. LF2 indicates the sedimentation of initial or reworked explosive products not far away from volcano centers, reflecting the proximal accumulation of volcano eruption-fed clasts or their resedimentation as debris flows. In addition, the submarine volcano eruptions may induced earthquakes that facilitate the resedimentation of unconsolidated sediments. LF3 contains abundant pyroclastic components and is commonly massive with rip-up mudstone clasts or usually interbedded with LF4. In addition, typical flute casts, scour structures and graded beddings in thin-interbedded layers of sandstone and mudstone are commonly observed, which also represents the sedimentation of debris flows or

  4. The 2014 eruptions of Pavlof Volcano, Alaska

    Science.gov (United States)

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

    2017-12-22

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

  5. An Interactive Geospatial Database and Visualization Approach to Early Warning Systems and Monitoring of Active Volcanoes: GEOWARN

    Science.gov (United States)

    Gogu, R. C.; Schwandner, F. M.; Hurni, L.; Dietrich, V. J.

    2002-12-01

    Large parts of southern and central Europe and the Pacific rim are situated in tectonically, seismic and volcanological extremely active zones. With the growth of population and tourism, vulnerability and risk towards natural hazards have expanded over large areas. Socio-economical aspects, land use, tourist and industrial planning as well as environmental protection increasingly require needs of natural hazard assessment. The availability of powerful and reliable satellite, geophysical and geochemical information and warning systems is therefore increasingly vital. Besides, once such systems have proven to be effective, they can be applied for similar purposes in other European areas and worldwide. Technologies today have proven that early warning of volcanic activity can be achieved by monitoring measurable changes in geophysical and geochemical parameters. Correlation between different monitored data sets, which would improve any prediction, is very scarce or missing. Visualisation of all spatial information and integration into an "intelligent cartographic concept" is of paramount interest in order to develop 2-, 3- and 4-dimensional models to approach the risk and emergency assessment as well as environmental and socio-economic planning. In the framework of the GEOWARN project, a database prototype for an Early Warning System (EWS) and monitoring of volcanic activity in case of hydrothermal-explosive and volcanic reactivation has been designed. The platform-independent, web-based, JAVA-programmed, interactive multidisciplinary multiparameter visualization software being developed at ETH allows expansion and utilization to other volcanoes, world-wide databases of volcanic unrest, or other types of natural hazard assessment. Within the project consortium, scientific data have been acquired on two pilot sites: Campi Flegrei (Italy) and Nisyros Greece, including 2&3D Topography and Bathymetry, Elevation (DEM) and Landscape models (DLM) derived from conventional

  6. Magmatic degassing, lava dome extrusion, and explosions from Mount Cleveland volcano, Alaska, 2011–2015: Insight into the continuous nature of volcanic activity over multi-year timescales

    Science.gov (United States)

    Werner, Cynthia; Kern, Christoph; Coppola, Diego; Lyons, John; Kelly, Peter; Wallace, Kristi; Schneider, David; Wessels, Rick

    2017-01-01

    Mount Cleveland volcano (1730 m) is one of the most active volcanoes in the Aleutian arc, Alaska, but heightened activity is rarely accompanied by geophysical signals, which makes interpretation of the activity difficult. In this study, we combine volcanic gas emissions measured for the first time in August 2015 with longer-term measurements of thermal output and lava extrusion rates between 2011 and 2015 calculated from MODIS satellite data with the aim to develop a better understanding of the nature of volcanic activity at Mount Cleveland. Degassing measurements were made in the month following two explosive events (21 July and 7 August 2015) and during a period of new dome growth in the summit crater. SO2 emission rates ranged from 400 to 860 t d− 1 and CO2/SO2 ratios were volcano. Rapid increases in the cumulative thermal output were often coincident with visual confirmation of dome growth or accumulations of tephra in the crater. The average rate of lava extrusion calculated for 9 periods of rapid increase in thermal output was 0.28 m3 s− 1, and the total volume extruded from 2011 to 2015 was 1.9–5.8 Mm3. The thermal output from the lava extrusion events only accounts for roughly half of the thermal budget, suggesting a continued presence of shallow magma in the upper conduit, likely driven by convection. Axisymmetric dome morphology and occasional drain back of lava into the conduit suggests low-viscosity magmas drive volcanism at Mount Cleveland. It follows also that only small overpressures can be maintained given the small domes and fluid magmas, which is consistent with the low explosivity of most of Mount Cleveland's eruptions. Changes between phases of dome growth and explosive activity are somewhat unpredictable and likely result from plugs that are related to the dome obtaining a critical dimension, or from small variations in the magma ascent rate that lead to crystallization-induced blockages in the upper conduit, thereby reducing

  7. Spectrum of the seismic-electromagnetic and acoustic waves caused by seismic and volcano activity

    Directory of Open Access Journals (Sweden)

    S. Koshevaya

    2005-01-01

    Full Text Available Modeling of the spectrum of the seismo-electromagnetic and acoustic waves, caused by seismic and volcanic activity, has been done. This spectrum includes the Electromagnetic Emission (EME, due to fracturing piezoelectrics in rocks and the Acoustic Emission (AE, caused by the excitation and the nonlinear passage of acoustic waves through the Earth's crust, the atmosphere, and the ionosphere. The investigated mechanism of the EME uses the model of fracturing and the crack motion. For its analysis, we consider a piezoelectric crystal under mechanical stresses, which cause the uniform crack motion, and, consequently, in the vicinity of the moving crack also cause non-stationary polarization currents. A possible spectrum of EME has been estimated. The underground fractures produce Very Low (VLF and Extremely Low Frequency (ELF acoustic waves, while the acoustic waves at higher frequencies present high losses and, on the Earth's surface, they are quite small and are not registered. The VLF acoustic wave is subject to nonlinearity under passage through the lithosphere that leads to the generation of higher harmonics and also frequency down-conversion, namely, increasing the ELF acoustic component on the Earth's surface. In turn, a nonlinear propagation of ELF acoustic wave in the atmosphere and the ionosphere leads to emerging the ultra low frequency (ULF acousto-gravity waves in the ionosphere and possible local excitation of plasma waves.

  8. North American Submarine Cable Association (NASCA) Submarine Cables

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data show the locations of in-service and out-of-service submarine cables that are owned by members of NASCA and located in U.S. territorial waters. More...

  9. A real-time framework for fast data retrieval in an image database of volcano activity scenarios

    Science.gov (United States)

    Aliotta, Marco Antonio; Cannata, Andrea; Cassisi, Carmelo; Ciancitto, Francesco; Montalto, Placido; Prestifilippo, Michele

    2015-04-01

    Explosive Activity at Stromboli Volcano (Aeolian Islands) is continuously monitored by INGV-OE in order to analyze its eruptive dynamics and specific scenarios. In particular, the images acquired from thermal cameras represent a big collection of data. In order to extract useful information from thermal image sequences, we need an efficient way to explore and retrieve information from a huge amount of data. In this work, a novel framework capable of fast data retrieval, using the "metric space" concept, is shown. In the light of it, we implemented an indexing algorithm related to similarity laws. The focal point is finding objects of a set that are "close" in relation to a given query, according to a similarity criterion. In order to perform this task, we performed morphological image processing techniques to each video frame, in order to map the shape area of each explosion into a closed curve, representing the explosion contour itself. In order to constitute a metric space, we chose a certain number of features obtained from parameters related to this closed curve and used them as objects of this metric space where similarity can be evaluated, using an appropriate "metric" function to calculate the distances. Unfortunately, this approach has to deal with an intrinsic issue involving the complexity and the number of distance functions to be calculated on a large amount of data. To overcome this drawback, we used a novel abstract data structure called "K-Pole Tree", having the property of minimizing the number of distances to be calculated among objects. Our method allows for fast retrieval of similar objects using an euclidean distance function among the features of the metric space. Thus, we can cluster explosions related to different kinds of volcanic activity, using "pivot" items. For example, given a known image sequence related to a particular type of explosion, it is possible to quickly and easily find all the image sequences that contain only similar

  10. The TOMO-ETNA experiment: an imaging active campaign at Mt. Etna volcano. Context, main objectives, working-plans and involved research projects

    Directory of Open Access Journals (Sweden)

    Jesús M. Ibáñez

    2016-09-01

    Full Text Available The TOMO-ETNA experiment was devised to image of the crust underlying the volcanic edifice and, possibly, its plumbing system by using passive and active refraction/reflection seismic methods. This experiment included activities both on-land and offshore with the main objective of obtaining a new high-resolution seismic tomography to improve the knowledge of the crustal structures existing beneath the Etna volcano and northeast Sicily up to Aeolian Islands. The TOMO ETNA experiment was divided in two phases. The first phase started on June 15, 2014 and finalized on July 24, 2014, with the withdrawal of two removable seismic networks (a Short Period Network and a Broadband network composed by 80 and 20 stations respectively deployed at Etna volcano and surrounding areas. During this first phase the oceanographic research vessel “Sarmiento de Gamboa” and the hydro-oceanographic vessel “Galatea” performed the offshore activities, which includes the deployment of ocean bottom seismometers (OBS, air-gun shooting for Wide Angle Seismic refraction (WAS, Multi-Channel Seismic (MCS reflection surveys, magnetic surveys and ROV (Remotely Operated Vehicle dives. This phase finished with the recovery of the short period seismic network. In the second phase the Broadband seismic network remained operative until October 28, 2014, and the R/V “Aegaeo” performed additional MCS surveys during November 19-27, 2014. Overall, the information deriving from TOMO-ETNA experiment could provide the answer to many uncertainties that have arisen while exploiting the large amount of data provided by the cutting-edge monitoring systems of Etna volcano and seismogenic area of eastern Sicily.

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

    Science.gov (United States)

    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.

  12. Study on the locational criteria for submarine rock repositories of low and medium level radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G. H.; Kang, W. J.; Kim, T. J. and others [Chungnam National Univ., Taejon (Korea, Republic of)

    1992-01-15

    Submarine repositories have significant advantages over their land counterparts locating close to the areas of daily human activities. Consequently, the construction of submarine repositories on the vast continental shelves around Korean seas is considered to be highly positive. In this context, the development of locational criteria primarily targeting the safety of submarine rock repositories is very important.The contents of the present study are: analyzing characteristics of marine environment: Search of potential hazards to, and environmental impact by, the submarine repositories; Investigation of the oceanographic, geochemical, ecological and sedimentological characteristics of estuaries and coastal seas. Locating potential hazards to submarine repositories by: Bibliographical search of accidents leading to the destruction of submarine structures by turbidity currents and other potentials; Review of turbidity currents. Consideration of environmental impact caused by submarine repositories: Logistics to minimize the environmental impacts in site selection; Removal and dispersion processes of radionuclides in sea water. Analyses of oceanographical characteristics of, and hazard potentials in, the Korean seas. Evaluation of the MOST 91-7 criteria for applicability to submarine repositories and the subsequent proposition of additional criteria.

  13. The iGrav superconducting gravimeter as a tool to monitor and study active volcanoes. Preliminary results from Mt. Etna (Italy)

    Science.gov (United States)

    Carbone, Daniele; Greco, Filippo

    2015-04-01

    Microgravity observation have been proven to be a valuable tool to monitor and study active volcanoes, thanks to their ability to detect mass redistributions induced by volcanic processes. Gravity changes are usually observed through time-lapse measurements. The latter can provide a good spatial resolution, but do not supply enough information on the rate at which the volcanic processes occur. Indeed, only changes between successive surveys (usually separated by intervals longer than 1 month) can be assessed. Continuous gravity measurements at active volcanoes are relatively rare, mainly due to the difficulty of running continuously spring instruments (the most widely used gravimeters), especially in harsh conditions. Indeed, spring gravimeters are subject to an important instrumental drift and are severely affected by ambient parameters (mainly ambient temperature). Superconducting gravimeters provide much better performances than spring instruments. In particular, the iGravTM superconducting gravimeter by GWR, more portable and easier to use than GWR Observatory Superconducting Gravimeters, features a sub-microGal precision, is practically drift-free (instrumental drift rate less than 0.5 microGal/month) and totally insensitive to local changes in ambient parameters. This instrument needs about 1kw of electricity to work, implying that it cannot be permanently installed in remote sites where mains electricity is not available. However, thanks to its stability and precision, the iGravTM meter can supply important information about volcano-related processes, over period of minutes to years, even if it is installed relatively far from the active structures. Here we report on the installation of an iGravTM meter at Mt. Etna (Italy). iGrav#16 was installed at the astrophysical observatory of Serra La Nave (southwestern flank of the volcano; 1740 m asl) in September 2014 and has acquired gravity data almost continuously even since, at a rate of 1Hz. The main features

  14. Numerical modelling of the transition from fissure- to central-type activity on volcanoes: a case study from Salina Island, Italy

    Science.gov (United States)

    Quareni, Francesca; Ventura, Guido; Mulargia, Francesco

    2001-08-01

    The evolution of the Rivi-Capo volcanic complex (Aeolian Archipelago) is characterised by a two-stage activity. Early phases of activity developed along a 1.5 km long eruptive fissure, whereas the later phase occurred from a central conduit. Geological and structural data indicate that the transition from fissure- to central-type activity was almost continuous in time, and no changes in the composition of the erupted products has been observed. Such a transition cannot be explained as a consequence of (a) flow localisation along a dike due to viscosity variation, or (b) emplacement of a magma reservoir by intersecting propagating cracks, or (c) re-orientation of the stress within the volcano due to gravity processes. In order to explain the change in vent geometry, a finite-element model has been developed which, using reliable parameters for basaltic rocks, accounts for a progressive melting of the host rocks enhanced by the flow of hot magma in the partially molten region. The proposed model allows one to explain the transition from fissure to central vent activity observed at Rivi-Capo as well as on other volcanoes.

  15. Thermal Activity Monitoring of an Active Volcano Using Landsat 8/OLI-TIRS Sensor Images: A Case Study at the Aso Volcanic Area in Southwest Japan

    National Research Council Canada - National Science Library

    Md Bodruddoza Mia; Yasuhiro Fujimitsu; Jun Nishijima

    2017-01-01

    .... For the first time, Landsat 8 TIRS thermal data were used in this study area to evaluate and monitor the recent thermal status of this volcano, situated in Southwest Japan, from 2013 to 2016 using four sets of images...

  16. Recent unrest at Canary Islands' Teide Volcano?

    National Research Council Canada - National Science Library

    Carracedo, Juan Carlos; Troll, Valentin R; Pérez, Francisco J; Badiola, Eduardo Rodríguez; Machín, Alex Hansen; Paris, Raphael; Guillou, Hervé; Scaillet, Stéphane

    2006-01-01

    ... that the volcanic unrest might culminate in renewed eruptive activity. Such was the situation for Teide volcano, located on Tenerife in the Canary Islands, when a mild seismic swarm during April...

  17. Cellular automaton simulations of the temporal pattern of activity of a volcano with an application to Vesuvius activity between 1631 and 1944

    Science.gov (United States)

    Piegari, E.; Di Maio, R.; Scandone, R.

    2012-04-01

    We simulate the volcanic activity of a basaltic stratovolcano by using a cellular automaton model where magma is allowed to rise through self-organized crack networks. Magma rises toward the surface by filling connected paths of fractures until the magma's density is less than, or equal to that of the surrounding rocks. If magma enters a less dense rock layer, it cools and thus solidifies; as a result, the local density profile is modified, and solid filled dikes are formed. We simulate the temporal evolution of such high density pathway of dikes which magma may eventually utilize to reach the surface with the occurrence of an eruption. Magma degassing is also taken into account by means of the relationship between the pressure-controlled water solubility and the lithostatic pressure. We study the statistical properties of the automaton by varying the model parameters and, in particular, the thickness of the uppermost rock layer, which controls the buoyancy rate of magma rise because of its low value of density. We show that, if the initial rock density profile is restored after each eruption because, for example, piecemeal or chaotic collapses, a characteristic timescale appears in the inter-event repose time distribution, which represents the average time that magma takes to form an high density pathway through the less dense rock layer. An application of the model to the statistics of the eruptive activity of the Somma-Vesuvius volcano for the 1631-1944 period is discussed.

  18. Submarine canyons off Madras Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    Submarine canyons off the coast of Madras, Tamil Nadu, India were studied during cruise of @iINS Kistna@@ as part of the IIOE programme They consist of hill-like projections and V-shaped valleys Their other features are also reported...

  19. Seafloor distribution and last glacial to postglacial activity of mud volcanoes on the Calabrian accretionary prism, Ionian Sea

    Science.gov (United States)

    Ceramicola, Silvia; Praeg, Daniel; Cova, Andrea; Accettella, Daniela; Zecchin, Massimo

    2014-06-01

    Mud volcanoes (MVs) are abundant along the eastern Mediterranean subduction zones, recording mud breccia extrusion over long timescales (106 years), but to date relatively few have been recognised in the northern Ionian Sea on the Calabrian accretionary prism (CAP). In the present study, the seafloor distribution and recent activity of MVs is investigated across a 35,600 km2 sector of the CAP using a regional acoustic dataset (multibeam bathymetric and backscatter imagery, integrated with subbottom profiles) locally ground-truthed by sediment cores. A total of 54 MVs are identified across water depths of 150-2,750 m using up to four geophysical criteria: distinctive morphology, high backscatter, unstratified subbottom facies and, in one case, a hydroacoustic flare. Fourteen MVs are identified from 3-4 criteria, of which five have been previously proven by cores containing mud breccia beneath up to 1.6 m of hemipelagic sediments (Madonna dello Ionio MVs 1-3, Pythagoras MV and the newly named Sartori MV), while nine others are identified for the first time (Athena, Catanzaro, Cerere, Diana, Giunone, Minerva, `right foot', Venere 1 and 2). Forty other as yet unnamed MVs are inferred from 1-2 geophysical criteria (three from distinctive morphology alone). All but one possible MV lie on the inner plateau of the CAP, landwards of the Calabrian Escarpment in a zone up to 120 km wide that includes the inner pre-Messinian wedge and the fore-arc basins, where they are interpreted to record the ascent from depth of overpressured fluids that interacted with tectonic structures and with evaporitic or shale seals within the fore-arc basins. The rise of fluids may have been triggered by post-Messinian out-of-sequence tectonism that affected the entire pre-Messinian prism, but Plio-Quaternary sedimentation rates and depositional styles support the inference that significant mud volcanism has taken place only on the inner plateau. Sedimentation rates across the CAP applied to a 12

  20. A re-evaluation of the Italian historical geomagnetic catalogue: implications for paleomagnetic dating at active Italian volcanoes

    Directory of Open Access Journals (Sweden)

    F. D'Ajello Caracciolo

    2011-06-01

    Full Text Available Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleosecular variation ((PSV are available. To this end, we re-evaluate the whole Italian geomagnetic directional dataset, consisting of 833 and 696 declination and inclination measurements, respectively, carried out since 1640 AD at several localities. All directions were relocated via the virtual geomagnetic pole method to Stromboli (38.8° N, 15.2° E, the rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method by French data (for period 1670–1789, and by nearby Italian sites/years (for periods 1640–1657 and 1790–1962. Using post-1825 declination values, we obtain a 0.46 ± 0.19° yr−1 westward drift of the geomagnetic field for Italy. The original observation years were modified, considering such drift value, to derive at a drift-corrected relocated dataset. Both datasets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000 and Pavon-Carrasco et al. (2009. However, the drift-corrected dataset minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933–1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated datasets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. The curve comparison suggests that both available field models yield the best available SV curve to perform paleomagnetic dating of 1600–1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the 19th century. For the 20th century, the global model by

  1. TOMO-ETNA MED-SUV.ISES an active seismic and passive seismic experiment at Mt. Etna volcano. An integrated marine and onland geophysical survey.

    Science.gov (United States)

    Ibáñez, Jesus. M.; Patane, Domenico; Puglisi, Guisseppe; Zuccarello, Lucciano; Bianco, Francesca; Luehr, Birger; Diaz-Moreno, Alejandro; Prudencio, Janire; Koulakov, Ivan; Del Pezzo, Edoardo; Cocina, Ornella; Coltelli, Mauro; Scarfi, Lucciano; De Gori, Pascuale; Carrion, Francisco

    2014-05-01

    An active seismic experiment to study the internal structure of Etna Volcano is going to carried out on Sicily and Aeolian islands. The main objective of the TOMO-ETNA MED-SUV.ISES experiment, beginning in summer 2014, is to perform a high resolution seismic tomography, in velocity and attenuation, in Southern Italy, by using active and passive seismic data, in an area encompassing outstanding volcanoes as Mt. Etna, and Aeolian volcanoes. The achievement of this objective is based on the integration and sharing of the in-situ marine and land experiments and observations and on the implementation of new instruments and monitoring systems. For the purpose, onshore and offshore seismic stations and passive and active seismic data generated both in marine and terrestrial environment will be used. Additionally, other geophysical data, mainly magnetic and gravimetric data will be considered to obtain a joint Upper Mantle-Crust structure that could permit to make progress in the understanding of the dynamic of the region. This multinational experiment which involves institutions from Spain, Italy, Germany, United Kingdom, Ireland, France, Malta, Portugal, Russia, USA and Mexico. During the experiment more than 6.600 air gun shots performed by the Spanish Oceanographic vessel "Sarmiento de Gamboa" will be recorder on a dense local seismic network consisting of 100 on land non-permanent stations, 70 on land permanent stations and 20-25 OBSs. Contemporaneously other marine geophysical measures will be performed using a marine Gravimeter LaCoste&Romberg Air-Sea Gravity System II and a Marine Magnetometer SeaSPY. The experiments will provide a unique data set in terms of data quantity and quality, and it will provide a detailed velocity and attenuation structural image of volcano edifice. The results will be essential in the development and interpretation of future volcanic models. It is noteworthy that this project is fully transversal, multidisciplinary and crosses several

  2. Preliminary volcano-hazard assessment for Mount Spurr Volcano, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Nye, Christopher J.

    2001-01-01

    Mount Spurr volcano is an ice- and snow-covered stratovolcano complex located in the north-central Cook Inlet region about 100 kilometers west of Anchorage, Alaska. Mount Spurr volcano consists of a breached stratovolcano, a lava dome at the summit of Mount Spurr, and Crater Peak vent, a small stratocone on the south flank of Mount Spurr volcano. Historical eruptions of Crater Peak occurred in 1953 and 1992. These eruptions were relatively small but explosive, and they dispersed volcanic ash over areas of interior, south-central, and southeastern Alaska. Individual ash clouds produced by the 1992 eruption drifted east, north, and south. Within a few days of the eruption, the south-moving ash cloud was detected over the North Atlantic. Pyroclastic flows that descended the south flank of Crater Peak during both historical eruptions initiated volcanic-debris flows or lahars that formed temporary debris dams across the Chakachatna River, the principal drainage south of Crater Peak. Prehistoric eruptions of Crater Peak and Mount Spurr generated clouds of volcanic ash, pyroclastic flows, and lahars that extended to the volcano flanks and beyond. A flank collapse on the southeast side of Mount Spurr generated a large debris avalanche that flowed about 20 kilometers beyond the volcano into the Chakachatna River valley. The debris-avalanche deposit probably formed a large, temporary debris dam across the Chakachatna River. The distribution and thickness of volcanic-ash deposits from Mount Spurr volcano in the Cook Inlet region indicate that volcanic-ash clouds from most prehistoric eruptions were as voluminous as those produced by the 1953 and 1992 eruptions. Clouds of volcanic ash emitted from the active vent, Crater Peak, would be a major hazard to all aircraft using Ted Stevens Anchorage International Airport and other local airports and, depending on wind direction, could drift a considerable distance beyond the volcano. Ash fall from future eruptions could disrupt many

  3. Preliminary volcano-hazard assessment for Augustine Volcano, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Waitt, Richard B.

    1998-01-01

    Augustine Volcano is a 1250-meter high stratovolcano in southwestern Cook Inlet about 280 kilometers southwest of Anchorage and within about 300 kilometers of more than half of the population of Alaska. Explosive eruptions have occurred six times since the early 1800s (1812, 1883, 1935, 1964-65, 1976, and 1986). The 1976 and 1986 eruptions began with an initial series of vent-clearing explosions and high vertical plumes of volcanic ash followed by pyroclastic flows, surges, and lahars on the volcano flanks. Unlike some prehistoric eruptions, a summit edifice collapse and debris avalanche did not occur in 1812, 1935, 1964-65, 1976, or 1986. However, early in the 1883 eruption, a portion of the volcano summit broke loose forming a debris avalanche that flowed to the sea. The avalanche initiated a small tsunami reported on the Kenai Peninsula at English Bay, 90 kilometers east of the volcano. Plumes of volcanic ash are a major hazard to jet aircraft using Anchorage International and other local airports. Ashfall from future eruptions could disrupt oil and gas operations and shipping activities in Cook Inlet. Eruptions similar to the historical and prehistoric eruptions are likely in Augustine's future.

  4. Seismic source dynamics of gas-piston activity at Kı̄lauea Volcano, Hawai‘i

    Science.gov (United States)

    Chouet, Bernard A.; Dawson, Phillip B.

    2015-01-01

    Since 2008, eruptive activity at the summit of Kı̄lauea Volcano, Hawai‘i has been confined to the new Overlook pit crater within the Halema‘uma‘u Crater. Among the broad range of magmatic processes observed in the new pit are recurring episodes of gas pistoning. The gas-piston activity is accompanied by seismic signals that are recorded by a broadband network deployed in the summit caldera. We use raw data recorded with this network to model the source mechanism of representative gas-piston events in a sequence that occurred on 20–25 August 2011 during a gentle inflation of the Kı̄lauea summit. To determine the source centroid location and source mechanism, we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous medium that takes topography into account. We apply a new waveform inversion method that accounts for the contributions from both translation and tilt in horizontal seismograms through the use of Green's functions representing the seismometer response to translation and tilt ground motions. This method enables a robust description of the source mechanism over the period range 1–10,000 s. Most of the seismic wavefield produced by gas-pistoning originates in a source region ∼1 km below the eastern perimeter of the Halema‘uma‘u pit crater. The observed waveforms are well explained by a simple volumetric source with geometry composed of two intersecting cracks featuring an east striking crack (dike) dipping 80°to the north, intersecting a north striking crack (another dike) dipping 65° to the east. Each gas-piston event is marked by a similar rapid inflation lasting a few minutes, trailed by a slower deflation ramp extending up to 15 min, attributed to the efficient coupling at the source centroid location of the pressure and momentum changes accompanying the growth and collapse of a layer of foam at the top of the lava column. Assuming a

  5. Seismic source dynamics of gas-piston activity at Kı¯lauea Volcano, Hawai`i

    Science.gov (United States)

    Chouet, Bernard; Dawson, Phillip

    2015-04-01

    Since 2008, eruptive activity at the summit of Kı¯lauea Volcano, Hawai`i has been confined to the new Overlook pit crater within the Halema`uma`u Crater. Among the broad range of magmatic processes observed in the new pit are recurring episodes of gas pistoning. The gas-piston activity is accompanied by seismic signals that are recorded by a broadband network deployed in the summit caldera. We use raw data recorded with this network to model the source mechanism of representative gas-piston events in a sequence that occurred on 20-25 August 2011 during a gentle inflation of the Kı¯lauea summit. To determine the source centroid location and source mechanism, we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous medium that takes topography into account. We apply a new waveform inversion method that accounts for the contributions from both translation and tilt in horizontal seismograms through the use of Green's functions representing the seismometer response to translation and tilt ground motions. This method enables a robust description of the source mechanism over the period range 1-10,000 s. Most of the seismic wavefield produced by gas-pistoning originates in a source region ˜1 km below the eastern perimeter of the Halema`uma`u pit crater. The observed waveforms are well explained by a simple volumetric source with geometry composed of two intersecting cracks featuring an east striking crack (dike) dipping 80°to the north, intersecting a north striking crack (another dike) dipping 65° to the east. Each gas-piston event is marked by a similar rapid inflation lasting a few minutes, trailed by a slower deflation ramp extending up to 15 min, attributed to the efficient coupling at the source centroid location of the pressure and momentum changes accompanying the growth and collapse of a layer of foam at the top of the lava column. Assuming a simple lumped parameter

  6. Volcanoes: observations and impact

    Science.gov (United States)

    Thurber, Clifford; Prejean, Stephanie G.

    2012-01-01

    Volcanoes are critical geologic hazards that challenge our ability to make long-term forecasts of their eruptive behaviors. They also have direct and indirect impacts on human lives and society. As is the case with many geologic phenomena, the time scales over which volcanoes evolve greatly exceed that of a human lifetime. On the other hand, the time scale over which a volcano can move from inactivity to eruption can be rather short: months, weeks, days, and even hours. Thus, scientific study and monitoring of volcanoes is essential to mitigate risk. There are thousands of volcanoes on Earth, and it is impractical to study and implement ground-based monitoring at them all. Fortunately, there are other effective means for volcano monitoring, including increasing capabilities for satellite-based technologies.

  7. Diversity and abundance of aerobic and anaerobic methane oxidizers at the Haakon Mosby Mud Volcano, Barents Sea.

    Science.gov (United States)

    Lösekann, Tina; Knittel, Katrin; Nadalig, Thierry; Fuchs, Bernhard; Niemann, Helge; Boetius, Antje; Amann, Rudolf

    2007-05-01

    Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methane-consuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56%+/-8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94%+/-2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and

  8. Diversity and Abundance of Aerobic and Anaerobic Methane Oxidizers at the Haakon Mosby Mud Volcano, Barents Sea▿

    Science.gov (United States)

    Lösekann, Tina; Knittel, Katrin; Nadalig, Thierry; Fuchs, Bernhard; Niemann, Helge; Boetius, Antje; Amann, Rudolf

    2007-01-01

    Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methane-consuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56% ± 8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94% ± 2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and

  9. A submarine fan in the Mesa Central, Mexico

    Science.gov (United States)

    Silva-Romo, G.; Arellano-Gil, J.; Mendoza-Rosales, C.; Nieto-Obregón, J.

    2000-10-01

    The contact between the Guerrero and Sierra Madre tectonostratigraphic terranes has been proposed to lie in the Mesa Central, east of the city of Zacatecas. Marine Triassic units have been assigned to the Guerrero Terrane. It is here proposed that this contact occurs to the west of the city of Zacatecas and the Triassic marine sequence assigned to the Sierra Madre Terrane. We analyzed the stratigraphic record and structural features of pre-Late Jurassic sequences at four localities in the Mesa Central. They contain a marine turbiditic Triassic unit, which includes La Bellena, Taray, and Zacatecas Formations, and a continental unit of probable Middle Jurassic age. Triassic sandstones were derived from a cratonic area, without the influence of arc volcanism. The sequences were affected by two phases of deformation. The Triassic formations are unconformably overlain by a continental volcano-sedimentary sequence that contains fragments of sandstones derived from the underlying unit. Sedimentologic characteristics of the Triassic unit fit a submarine fan model. The submarine fan developed at the continental margin of Pangaea during Triassic times. Turbidite associations in the San Rafael Area indicate a middle fan depositional environment, while in the Real de Catorce Area, they correspond to the distal part (basin plain facies). At La Ballena and Zacatecas the turbidite associations occur in the middle part and perhaps the external part of the fan.

  10. Soufriere Hills Volcano

    Science.gov (United States)

    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 part of NASA

  11. Decoding recent mud-volcano activity in the westernmost Mediterranean: Evidence from sediment/porewater data and geochemical modeling

    Science.gov (United States)

    López-Rodríguez, Carmina; Martínez-Ruíz, Francisca; Mogollón, José M.; Comas, Menchu; Nieto, Fernando; Böning, Philipp; Pahnke, Katharina; Sapart, Célia; De Lange, Gert J.

    2017-04-01

    Recent studies have demonstrated the occurrence of active mud volcanism in the West Alboran Basin. Though most of the mud volcanoes (MVs) discovered in this region are dormant, a few structures evidence active hydrocarbon venting, as Carmen MV. This study focuses on sedimentological and geochemical investigations on one piston core, GP05PC, recovered from the summit of Carmen MV during the Gasalb-Pelagia cruise (2011). Although the full core consists of mud breccia sediments, a dramatic change occurs between enhanced methane concentrations in its lowermost and dissolved SO42- in its uppermost sediments. At the boundary of 150 cm, methane is oxidized and sulphate reduced. In the lowermost interval, the depletion of major elements (i.e., Ca2+ and Mg2+), the enrichment of trace species (i.e., Li+ and B) and the radiogenic 87Sr all point to a deep fluid source. The δ18Opw and δDpw compositions of pore water (5.7‰ and -10‰ VSMOW, respectively) together with the mineralogical results (presence of randomly insterstrafied (R0) illite-smectite minerals (I/S) to more illitic (>50% I) and ordered ones (R1-R3)) indicate smectite to illite transformation at greater depth and support smectite dehydration as the main porewater freshening mechanism. Water formation temperatures calculated through the application of empirical geo-thermometers (K-Na, K-Mg and K-Ca) together with the presence from I/S mixed layers (R3) suggest that fluids were generated at temperatures 100-200°C. This temperature indicates that, under a regional geothermal gradient, the fluid source originates from 8 km depth. From an adjacent borehole it is known that sedimentary units of Early to Middle Miocene age occur at that depth (Jurado and Comas et al., 1992). The δ13Cmethane and δDmethane composition of methane (-59‰ VPDB and -184‰ VSMOW, respectively) of the deepest sample also may be associated to a thermogenic origin. The absence of hemipelagic sediment draping, the distinctive seawater

  12. Yellowstone Volcano Observatory

    Science.gov (United States)

    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.

  13. Slope failures induced by the December 2002 eruption at Stromboli Volcano

    Science.gov (United States)

    Tommasi, Paolo; Baldi, Paolo; Chiocci, Francesco Latino; Coltelli, Mauro; Marsella, Maria; Romagnoli, Claudia

    We reconstruct the sequence of landslides that occurred soon after the beginning of the December 2002 eruption on the NW flank of Stromboli volcano. Landslides involved the northeastern part of the Sciara del Fuoco (SdF) slope, an old collapse scar filled by products of volcanic activity, producing tsunami waves that severely damaged the coast of the island of Stromboli. Volumes of the mass detached from the subaerial and submarine slope were quantified by comparing preslide and postslide slope surfaces obtained by aerophotogrammetric and bathymetric data, which also allowed, in conjunction with field observations and helicopter surveys, the reconstruction of geometry and kinematics of landslides. According to the reconstructed sequence, 2 days after the beginning of the eruption, the upper part of the NE sector of the SdF slope experienced major displacements (few tens of meters). Movements propagated downslope and affected the nearshore portion of the submerged slope without a rapid sliding of the displaced mass into the sea. The following hours were characterized by a progressive increase of deformations, localized along shear zones extending over two thirds of the subaerial slope. This phase proceeded until a submarine slide about 6 × 106 m3 in volume occurred, causing a first tsunami wave. The subaerial mass delimited by the shear zones and unbuttressed at its foot, then slipped into the sea producing a second tsunami wave. The main landslide event (and the minor slumps which followed) removed a volume of about 10 × 106 m3 of the infilling deposit, to a thickness of at least 65 m. Hypotheses were formulated on the mechanisms that controlled the different phases of the instability sequence. Since hydraulic and stress/strain conditions progressively changed during the slope evolution, the formulated mechanisms are also based on geotechnical analyses and considerations on the mechanical behavior of volcaniclastic materials. The process that led to the landslide

  14. Submarine Warfare in the 20th & 21st Centuries: A Bibliography

    National Research Council Canada - National Science Library

    Huygen, Michaele

    2003-01-01

    There are constant motions in the sea caused by atmospheric and seabed activities volcanic disruptions marine animals ships and submarines -- all of which create what is called the ambient noise level of the oceans...

  15. Volcanic activity in the Acambay Graben: a < 25 Ka subplinian eruption from the Temascalcingo volcano and implications for volcanic hazard.

    Science.gov (United States)

    Pedrazzi, Dario; Aguirre Díaz, Gerardo; Sunyé Puchol, Ivan; Bartolini, Stefania; Geyer, Adelina

    2016-04-01

    The Trans-Mexican Volcanic Belt (TMVB) contains a large number of stratovolcanoes, some well-known, as Popocatepetl, Iztaccihuatl, Nevado de Toluca, or Colima and many others of more modest dimensions that are not well known but constitute the majority in the TMVB. Such volcanoes are, for example, Tequila, San Juan, Sangangüey, Cerro Culiacán, Cerro Grande, El Zamorano, La Joya, Palo Huerfano, Jocotitlán, Altamirano and Temascalcingo, among many others. The Temascalcingo volcano (TV) is an andesitic-dacitic stratovolcano located in the Trans-Mexican Volcanic Belt (TMVB) at the eastern part of the Acambay Graben (northwest portion of Estado de México). The TV is composed mainly by dacitic, porphyritic lavas, block and ash deposits and subordinate pumice fall deposits and ignimbrites (Roldán-Quintana et al., 2011). The volcanic structure includes a summit caldera that has a rectangular shape, 2.5×3.5 km, with the largest side oriented E-W, parallel to major normal faults affecting the edifice. The San Mateo Pumice eruption is one of the greatest paroxysmal episodes of this volcano with pumice deposits mainly exposed at the scarp of the Acambay-Tixmadeje fault and at the northern and northeastern flanks of TV. It overlies a paleosol dated at 25 Ka. A NE-trending dispersion was obtained from field data covering an area of at least 80 km2. These deposits overlie older lava flows and mud flows and are discontinuously covered and eroded by younger reworked deposits of Temascalcingo volcano. This event represents a highly explosive phase that generated a relatively thick and widespread pumice fallout deposit that may occur again in future eruptions. A similar eruption today would have a significantly impact in the region, overall due to the fact that there has been no systematic assessment of the volcanic hazard in any of the studies that have been conducted so far in the area. So, this is a pending and urgent subject that must be tackled without delay. Financed by

  16. Ambient Noise Tomography at Bezymianny Volcano, Kamchatka

    Science.gov (United States)

    Shuler, A. E.; Ekström, G.; West, M.; Senyukov, S.

    2008-12-01

    Bezymianny Volcano is an active stratovolcano located in the Kluychevskoy volcanic group on the Kamchatka Peninsula in eastern Russia. Since its dramatic sector collapse eruption in 1956, the volcano's activity has been characterized by nearly twice annual plinian eruptions accompanying ongoing lava-dome growth. Its frequent eruptions and similarity to Mt. St. Helens have made it the target of a multifaceted geologic and geophysical project supported by the NSF Partners in Research and Education (PIRE) program. Since mid- 2006, the volcano has been monitored by a broadband seismic array that is currently composed of 8 stations within 10 kilometers of the active dome. In this project, we use continuous data from these stations to investigate the static and dynamic structure of the volcano. Using methods similar to those used by Brenguier et al. (2007, 2008), we estimate the Green's function for each pair of stations by cross-correlating day-long time series of ambient noise. Paths with high signal-to-noise ratios can be used to estimate group velocity dispersion curves. From these measurements, we work towards constructing the first velocity model of this volcano. Furthermore, we begin to test whether measurements of ambient noise can be used to monitor changes inside the volcano prior to eruptive activity. These problems will continue to be addressed as more data becomes available in future field seasons.

  17. Swath sonar mapping of Earth's submarine plate boundaries

    Science.gov (United States)

    Carbotte, S. M.; Ferrini, V. L.; Celnick, M.; Nitsche, F. O.; Ryan, W. B. F.

    2014-12-01

    The recent loss of Malaysia Airlines flight MH370 in an area of the Indian Ocean where less than 5% of the seafloor is mapped with depth sounding data (Smith and Marks, EOS 2014) highlights the striking lack of detailed knowledge of the topography of the seabed for much of the worlds' oceans. Advances in swath sonar mapping technology over the past 30 years have led to dramatic improvements in our capability to map the seabed. However, the oceans are vast and only an estimated 10% of the seafloor has been mapped with these systems. Furthermore, the available coverage is highly heterogeneous and focused within areas of national strategic priority and community scientific interest. The major plate boundaries that encircle the globe, most of which are located in the submarine environment, have been a significant focus of marine geoscience research since the advent of swath sonar mapping. While the location of these plate boundaries are well defined from satellite-derived bathymetry, significant regions remain unmapped at the high-resolutions provided by swath sonars and that are needed to study active volcanic and tectonic plate boundary processes. Within the plate interiors, some fossil plate boundary zones, major hotspot volcanoes, and other volcanic provinces have been the focus of dedicated research programs. Away from these major tectonic structures, swath mapping coverage is limited to sparse ocean transit lines which often reveal previously unknown deep-sea channels and other little studied sedimentary structures not resolvable in existing low-resolution global compilations, highlighting the value of these data even in the tectonically quiet plate interiors. Here, we give an overview of multibeam swath sonar mapping of the major plate boundaries of the globe as extracted from public archives. Significant quantities of swath sonar data acquired from deep-sea regions are in restricted-access international archives. Open access to more of these data sets would

  18. Eruption of Shiveluch Volcano, Kamchatka Peninsula

    Science.gov (United States)

    2007-01-01

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

  19. Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Founded in 1912 at the edge of the caldera of Kīlauea Volcano, HVO was the vision of Thomas A. Jaggar, Jr., a geologist from the Massachusetts Institute of Technology, whose studies of natural disasters around the world had convinced him that systematic, continuous observations of seismic and volcanic activity were needed to better understand—and potentially predict—earthquakes and volcanic eruptions. Jaggar summarized the aim of HVO by stating that “the work should be humanitarian” and have the goals of developing “prediction and methods of protecting life and property on the basis of sound scientific achievement.” These goals align well with those of the USGS, whose mission is to serve the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage natural resources; and enhance and protect our quality of life.

  20. SCICEX: Submarine Arctic Science Program, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration among the operational Navy, research agencies, and the marine research community...

  1. Measuring currents in submarine canyons: technological and scientific progress in the past 30 years

    Science.gov (United States)

    Xu, J. P.

    2011-01-01

    The development and application of acoustic and optical technologies and of accurate positioning systems in the past 30 years have opened new frontiers in the submarine canyon research communities. This paper reviews several key advancements in both technology and science in the field of currents in submarine canyons since the1979 publication of Currents in Submarine Canyons and Other Sea Valleys by Francis Shepard and colleagues. Precise placements of high-resolution, high-frequency instruments have not only allowed researchers to collect new data that are essential for advancing and generalizing theories governing the canyon currents, but have also revealed new natural phenomena that challenge the understandings of the theorists and experimenters in their predictions of submarine canyon flow fields. Baroclinic motions at tidal frequencies, found to be intensified both up canyon and toward the canyon floor, dominate the flow field and control the sediment transport processes in submarine canyons. Turbidity currents are found to frequently occur in active submarine canyons such as Monterey Canyon. These turbidity currents have maximum speeds of nearly 200 cm/s, much smaller than the speeds of turbidity currents in geological time, but still very destructive. In addition to traditional Eulerian measurements, Lagrangian flow data are essential in quantifying water and sediment transport in submarine canyons. A concerted experiment with multiple monitoring stations along the canyon axis and on nearby shelves is required to characterize the storm-trigger mechanism for turbidity currents.

  2. Submarine thermal springs on the Galapagos Rift

    Science.gov (United States)

    Corliss, J.B.; Dymond, J.; Gordon, L.I.; Edmond, J.M.; Von Herzen, R. P.; Ballard, Richard D.; Green, K.; Williams, D.; Bainbridge, A.; Crane, K.; Van Andel, T. H.

    1979-01-01

    The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis

  3. When the hazard you're monitoring is the least of your troubles… the early days of a ubiquitous computing citizen science initiative on active volcanoes

    Science.gov (United States)

    van Manen, S. M.; Richards, M.; Seaton, R.; Cameron, I.; Avard, G.; Martinez, M.

    2014-12-01

    Approximately 500 million people live in close proximity to one or more of the world's 1500 active volcanoes, and this number is set to increase through population growth. The corresponding human, social, environmental and economic costs of volcanic activity are likewise set to rise. Monitoring of active volcanoes is imperative to minimize the impact of volcanic activity. However, people's responses towards risk are not just determined by objective scientific information, but also by socio-cognitive factors such as hazard salience; risk perception; anxiety levels and sense of self efficacy. This project aims to take a citizen science approach to the monitoring of hazardous volcanic gases: a low-cost automated ubiquitous technology station will increase spatial and temporal data resolution while providing citizens access to relevant, accurate, timely and local information. This means a single data stream can be used to develop a better understanding of volcanic degassing and raise levels of hazard salience and increase feelings of self efficacy. A year and two prototypes into the project, this work presents the lessons learnt to date. Careful consideration was given to the station design in light of the harsh conditions it may encounter. Once the first prototypes were built, results from the initial lab tests were encouraging. Yet it wasn't until the stations were taken into the field that unexpected challenges were encountered: humans. During the very first field trial the prototype was vandalised, our second attempt was thwarted by customs and courier services. As a result, we've had to be flexible in our approach and adapt our strategy and station design in response to these events, which will eventually result in a better outcome. However, this case study serves as a reminder of the importance of considering factors beyond the equipment, data, interpretation and involvement of the public, when planning and implementing a citizen science initiative.

  4. An ongoing large submarine landslide at the Japan trench

    Science.gov (United States)

    Nitta, S.; Kasaya, T.; Miura, S.; Kawamura, K.

    2013-12-01

    This paper deals with an active submarine landslide on a landward trench slope in the Japan trench. Studied area is located on the upper terrace ranging from 400 to 1200 m in water depth, off Sendai, northeast Japan. We have surveyed in detail the seabed topography using a multi narrow beam (hereafter MBES) and a subbottom profiler (hereafter SBP) during the cruise MR12-E02 of R/V Mirai. The survey lines were 12 lines in N-S, and 3 lines in E-W, and situated in the region from 141°45'E, 37°40'N to 142°33'E, 38°32'N. Moreover, we used multi-channel seismic profile by the cruise KR04-10 of R/V Kairei in the interpretation of the SBP results. In general, horseshoe-shaped depressions of about 100 km wide along the trench slope are arrayed along the Japan trench. It has thought that they were formed by large submarine landslides, but we could not understand critically the relationship between the depressions and the submarine landslides. Based on the survey results, we found signals of an active submarine landslide in the depression as follows. 1) We observed arcuate-shaped lineaments, which are sub-parallel to a horseshoe-shaped depression. The lineaments concentrate in the south region from 38°N at about 20 km wide. These lineaments are formed by deformation structures as anticlines, synclines and normal fault sense displacements. 2) Most of the synclines and anticlines are not buried to form the lineaments. 3) Normal faults cutting about 1 km deep are observed in a multi-channel seismic profile. The normal faults are located just below the arcuate-shaped lineaments, and are tilted eastward being the downslope direction. It indicates a large submarine landslide. We concluded that the arcuate-shaped lineaments were generated by surface sediment movement with the submarine landsliding. We think that the submarine landslide of about 20 km wide and about 1 km thick move continuously down the landward trench slope. This would be the formation process of the horseshoe

  5. Environmental assessment of submarine power cables

    Energy Technology Data Exchange (ETDEWEB)

    Isus, Daniel; Martinez, Juan D. [Grupo General Cable Sistemas, S.A., 08560-Manlleu, Barcelona (Spain); Arteche, Amaya; Del Rio, Carmen; Madina, Virginia [Tecnalia Research and Innovation, 20009 San Sebastian (Spain)

    2011-03-15

    Extensive analyses conducted by the European Community revealed that offshore wind energy have relatively benign effects on the marine environment by comparison to other forms of electric power generation [1]. However, the materials employed in offshore wind power farms suffer major changes to be confined to the marine environment at extreme conditions: saline medium, hydrostatic pressure... which can produce an important corrosion effect. This phenomenon can affect on the one hand, to the material from the structural viewpoint and on the other hand, to the marine environment. In this sense, to better understand the environmental impacts of generating electricity from offshore wind energy, this study evaluated the life cycle assessment for some new designs of submarine power cables developed by General Cable. To achieve this goal, three approaches have been carried out: leaching tests, eco-toxicity tests and Life Cycle Assessment (LCA) methodologies. All of them are aimed to obtaining quantitative data for environmental assessment of selected submarine cables. LCA is a method used to assess environmental aspects and potential impacts of a product or activity. LCA does not include financial and social factors, which means that the results of an LCA cannot exclusively form the basis for assessment of a product's sustainability. Leaching tests results allowed to conclude that pH of seawater did not significantly changed by the presence of submarine three-core cables. Although, it was slightly higher in case of broken cable, pH values were nearly equals. Concerning to the heavy metals which could migrate to the aquatic medium, there were significant differences in both scenarios. The leaching of zinc is the major environmental concern during undersea operation of undamaged cables whereas the fully sectioned three-core cable produced the migration of significant quantities of copper and iron apart from the zinc migrated from the galvanized steel. Thus, the tar

  6. Lahar hazards at Agua volcano, Guatemala

    Science.gov (United States)

    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.

  7. Self-potential chenges associated with volcanic activity: Short-term signals associated with March 9, 1998 eruption on La Fournaise volcano (Reunion Island

    Directory of Open Access Journals (Sweden)

    P. Yvetot

    2001-06-01

    Full Text Available After six years of quietness La Fournaise volcano entered into activity on March 9, 1998. Fissures opened gradually downwards on the northern flank of the cone. Two cones, Kapor and Krafft built, from which lava poured until September 1998. Several other vents opened during this eruption. Mappings, surveys, and continuous recordings of the Self-Potential have been performed on the volcano for twenty years. SP mappings disclose the variability of large scale SP anomalies due to the modification of the hydrothermal system over some ten years. Most of the eruptions take place along a Main Fracture Zone (MFZ in which ground water flows prevail. SP measurements have also regularly been made on the northern flank of the cone, on a west-east profile crossing the MFZ. Between 1981 and 1992 an enlargement and a shift of the MFZ to the east are evidenced. In particular, the eastern fissural axis trending N35°E could be related to the possible collapse of the east flank of the volcano. After a decrease between 1992 and 1997, the SP anomaly was enhanced again by the 1998 eruption. Short scale, about 250 m wide, 750 mV amplitude anomalies were superimposed on a large scale one, 2500 m wide, and about 250 mV in amplitude. For several years, continuous stations have been measuring the electric field along two directions, with a 20 s sampling, in order to record the genesis of SP signals associated with the volcanic activity. Oscillations belonging to the ULF band were evidenced several days before the 1988 eruption, some of them at 9 km from the summit. Their amplitude reached several tens mV/km. These oscillations sometimes present a phase lag from one station to another; they progressively shift towards the location of the future effusive vents. The polarisation of the oscillations is similar to the polarisation of longer SP variations (1 h period or more and are correlated with the structural anisotropy. Finally, during the last hours preceding the

  8. A New Perspective on Mount St. Helens - Dramatic Landform Change and Associated Hazards at the Most Active Volcano in the Cascade Range

    Science.gov (United States)

    Ramsey, David W.; Driedger, Carolyn L.; Schilling, Steve P.

    2008-01-01

    Mount St. Helens has erupted more frequently than any other volcano in the Cascade Range during the past 4,000 years. The volcano has exhibited a variety of eruption styles?explosive eruptions of pumice and ash, slow but continuous extrusions of viscous lava, and eruptions of fluid lava. Evidence of the volcano?s older eruptions is recorded in the rocks that build and the deposits that flank the mountain. Eruptions at Mount St. Helens over the past three decades serve as reminders of the powerful geologic forces that are reshaping the landscape of the Pacific Northwest. On May 18, 1980, a massive landslide and catastrophic explosive eruption tore away 2.7 cubic kilometers of the mountain and opened a gaping, north-facing crater. Lahars flowed more than 120 kilometers downstream, destroying bridges, roads, and buildings. Ash from the eruption fell as far away as western South Dakota. Reconstruction of the volcano began almost immediately. Between 1980 and 1986, 80 million cubic meters of viscous lava extruded episodically onto the crater floor, sometimes accompanied by minor explosions and small lahars. A lava dome grew to a height of 267 meters, taller than the highest buildings in the nearby city of Portland, Oregon. Crater Glacier formed in the deeply shaded niche between the 1980-86 lava dome and the south crater wall. Its tongues of ice flowed around the east and west sides of the dome. Between 1989 and 1991, multiple explosions of steam and ash rocked the volcano, possibly a result of infiltrating rainfall being heated in the still-hot interior of the dome and underlying crater floor. In September 2004, rising magma caused earthquake swarms and deformation of the crater floor and glacier, which indicated that Mount St. Helens might erupt again soon. On October 1, 2004, a steam and ash explosion signaled the beginning of a new phase of eruptive activity at the volcano. On October 11, hot rock reached the surface and began building a new lava dome immediately

  9. Deformation microstructures and timing of a large submarine landslide drilled offshore Martinique (IODP Exp. 340)

    Science.gov (United States)

    Guyard, H.; Le Friant, A.; Brunet, M.; Boudon, G.; Emmanuel, L.; Caron, B.; Villemant, B.; Feuillet, N.

    2015-12-01

    Flank-instabilities constitute a recurrent process in the long-term evolution of many volcanoes. A very large submarine landslide deposit (~2100 km2, ~300 km3) drilled southwest Martinique island during the IODP Exp. 340 in 2012 is likely associated with one (or more) major volcanic flank collapse of Mount Pelée during the Late Pleistocene. A recent study revealed that this D1/D2 deposit is emergent in its central part, frontally confined, and mainly comprises remobilized seafloor sediments rather than debris avalanche material from the volcanic edifice (Brunet et al., subm). Here, we investigate the sedimentary microstructures and timing of deformation from the central (Hole 1400B, ~37 km from the coastline) and distal (Hole 1399A, ~70 km from the coastline) units of the D1/D2 deposit, in order to better understand the emplacement dynamics of such potentially tsunamigenic submarine landslides. High resolution CT-Scan analyses were continuously performed on more than 300 m of sediment cores, in order to characterize and distinguish the internal architecture and the complex deformation features of the sediments at each drilling site. The establishment of the stratigraphy, based on δ18O measurements and AMS 14C dating, is still in progress and may confirm the possible link between the submarine landslide deposits and the flank collapse scars observed on the subaerial part of Martinique. These new insights into the timing and emplacement processes of this large submarine landslide will have important implications for tsunami hazards. ReferenceBrunet, M., Le Friant, A., Boudon, G., Lafuerza, S., Talling, P., Hornbach, M., Lebas, E., Guyard, H., and IODP Expedition 340 science party, submitted. Composition, geometry and emplacement dynamics of a large volcanic island landslide offshore Martinique: from volcano flank-collapse to seafloor sediment failure? Geochemistry, Geophysics, Geosystems.

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

    Science.gov (United States)

    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

  11. Common processes at unique volcanoes – a volcanological conundrum

    Directory of Open Access Journals (Sweden)

    Katharine eCashman

    2014-11-01

    Full Text Available 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.

  12. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another

  13. Metal enrichment of soils following the April 2012-2013 eruptive activity of the Popocatépetl volcano, Puebla, Mexico.

    Science.gov (United States)

    Rodriguez-Espinosa, P F; Jonathan, M P; Morales-García, S S; Villegas, Lorena Elizabeth Campos; Martínez-Tavera, E; Muñoz-Sevilla, N P; Cardona, Miguel Alvarado

    2015-11-01

    We analyzed the total (Zn, Pb, Ni, Hg, Cr, Cd, Cu, As) and partially leachable metals (PLMs) in 25 ash and soil samples from recent (2012-2013) eruptions of the Popocatépetl Volcano in Central Mexico. More recent ash and soil samples from volcanic activity in 2012-2013 had higher metal concentrations than older samples from eruptions in 1997 suggesting that the naturally highly volatile and mobile metals leach into nearby fresh water sources. The higher proportions of As (74.72%), Zn (44.64%), Cu (42.50%), and Hg (32.86%) reflect not only their considerable mobility but also the fact that they are dissolved and accumulated quickly following an eruption. Comparison of our concentration patterns with sediment quality guidelines indicates that the Cu, Cd, Cr, Hg, Ni, and Pb concentrations are higher than permissible limits; this situation must be monitored closely as these concentrations may reach lethal levels in the future.

  14. Exploring the links between volcano flank collapse and magma evolution: Fogo oceanic shield volcano, Cape Verde

    Science.gov (United States)

    Cornu, Melodie-Neige; Paris, Raphael; Doucelance, Regis; Bachelery, Patrick; Guillou, Hervé

    2017-04-01

    Mass wasting of oceanic shield volcanoes is largely documented through the recognition of collapse scars and submarine debris fans. However, it is actually difficult to infer the mechanisms controlling volcano flank failures that potentially imply tens to hundreds of km3. Studies coupling detailed petrological and geochemical analyses of eruptive products hold clues for better understanding the relationships between magma sources, the plumbing system, and flank instability. Our study aims at tracking potential variations of magma source, storage and transport beneath Fogo shield volcano (Cape Verde) before and after its major flank collapse. We also provide a geochronological framework of this magmatic evolution through new radiometric ages (K-Ar and Ar-Ar) of both pre-collapse and post-collapse lavas. The central part of Fogo volcanic edifice is truncated by an 8 km-wide caldera opened to the East, corresponding to the scar of the last flank collapse (Monte Amarelo collapse, Late Pleistocene, 150 km3). Lavas sampled at the base of the scar (the so-called Bordeira) yielded ages between 158 and 136 ka. The age of the collapse is constrained between 68 ka (youngest lava flow cut by the collapse scar) and 59 ka (oldest lava flow overlapping the scar). The collapse walls display a complex structural, intrusive and eruptive history. Undersaturated volcanism (SiO2elements analyses indicate that the pre-collapse lavas are significantly less differentiated than post-collapse lavas, with a peak of alkalis at the collapse. Rare-earth elements concentration decreases with time, with a notable positive anomaly before the collapse. The evolution of the isotopic ratios (Sr, Nd and Pb) through time displays unusual V-shaped profiles centered around the collapse. The occurrence of the Monte Amarelo collapse is thus not disconnected from the magmatic evolution, both at the crustal and mantellic levels. Our results also point out the importance and relative frequency of explosive

  15. Classification of Martian Volcanoes on Basis of Volcano Ground Ice Interaction

    Science.gov (United States)

    Helgason, J.

    2000-08-01

    Most Martian volcanoes have common morphological features indicating mass wasting and erosion compatible with large scale break down of ground ice. While some features suggest the ground ice melted rapidly resulting in catastrophic erosive events, other features indicate a slow melting process (e.g sublimation) resulting in collapse structures. To determine relative volcano age and activity on Mars it is suggested that volcano interactions with an overlying ice sheet may be helpful. Examples of the various morphological features indicating volcano-ice interaction are drawn from the literature: (1) valley formation that probably formed in response to joekulhlaups and subglacial volcanism, (2) isolated thermocarst depressions probably formed by geothermal melting of ground ice, (3) large scale sublimation of distal strata, (4) small fluvial valleys, (5) large scale failure of volcano flanks through aureole development, (6) rimless craters without ash collars, (7) rampart craters on volcanoes, (8) channels, (9) mud flows or lahars. A Viking Orbiter image showing possible thermocarst landscape on the flank of the volcano Hadriaca Patera (Dao Vallis). Although various other explanations can account for some of these features they are all compatible with a ground ice-volcano interaction. These features suggests that to an extent most Martian volcanoes are covered with sheet of ground ice of variable thickness. Over a vast time interval this ground ice layer (or ice sheet) has been failing to a variable extent and in a number of ways depending on different volcano characteristics. As a result it is suggested that Martian volcanoes can be classified or assigned an evolutionary status depending on how widespread their interaction is with the ground ice layer. Thus, for example, within the Tharsis region the volcanoes Olympus Mons and Arsia Mons can be regarded as two evolutionary end points. Volcanism in the former has completely built up through and destroyed the ice sheet

  16. Time-series analysis of fissure-fed multi-vent activity: a snapshot from the July 2014 eruption of Etna volcano (Italy)

    Science.gov (United States)

    Spina, L.; Taddeucci, J.; Cannata, A.; Sciotto, M.; Del Bello, E.; Scarlato, P.; Kueppers, U.; Andronico, D.; Privitera, E.; Ricci, T.; Pena-Fernandez, J.; Sesterhenn, J.; Dingwell, D. B.

    2017-07-01

    On 5 July 2014, an eruptive fissure opened on the eastern flank of Etna volcano (Italy) at 3.000 m a.s.l. Strombolian activity and lava effusion occurred simultaneously at two neighbouring vents. In the following weeks, eruptive activity led to the build-up of two cones, tens of meters high, here named Crater N and Crater S. To characterize the short-term (days) dynamics of this multi-vent system, we performed a multi-parametric investigation by means of a dense instrumental network. The experimental setup, deployed on July 15-16th at ca. 300 m from the eruption site, comprised two broadband seismometers and three microphones as well as high speed video and thermal cameras. Thermal analyses enabled us to characterize the style of eruptive activity at each vent. In particular, explosive activity at Crater N featured higher thermal amplitudes and a lower explosion frequency than at Crater S. Several episodes of switching between puffing and Strombolian activity were noted at Crater S through both visual observation and thermal data; oppositely, Crater N exhibited a quasi-periodic activity. The quantification of the eruptive style of each vent enabled us to infer the geometry of the eruptive system: a branched conduit, prone to rapid changes of gas flux accommodated at the most inclined conduit (i.e. Crater S). Accordingly, we were able to correctly interpret acoustic data and thereby extend the characterization of this two-vent system.

  17. Tornillos modeled as self-oscillations of fluid filling a cavity: Application to the 1992-1993 activity at Galeras volcano, Colombia

    Science.gov (United States)

    Konstantinou, K. I.

    2015-01-01

    Tornillos are quasi-monochromatic seismic signals with a slowly decaying coda that are observed near active volcanoes and geothermal areas worldwide. In this work a lumped parameter model describing the tornillo source process as the self-oscillations of fluid filling a cavity is investigated. A nonlinear ordinary differential equation is derived that governs the behavior of the model taking into account viscous and nonlinear damping as well as the reaction force of the fluid inside the cavity. This equation is numerically integrated both for different cavity sizes and different fluids of volcanological interest, such as gas (H2O + CO2, H2O + SO2) and gas-particle mixtures (ash-SO2, water droplets-H2O). This cavity model predicts that when the filling fluid is a mixture of ash and SO2 the signal duration will increase until the mixture becomes enriched in ash and then the duration exhibits a decrease. Additionally, the damping coefficients (=1/2Q) of the synthetic signals are estimated in the range between 0.002 and 0.014. Both results agree well with the temporal variation of tornillos duration and the estimated Q quality factors/damping coefficients observed at Galeras volcano. In the context of the cavity model, tornillo frequency variations from 4 Hz to 1 Hz observed prior to eruptions can be interpreted as the result of fluid composition changes as more ash particles are added. This is in agreement with the observation that gas accumulation at Galeras was a steady rather than an episodic process and that tornillos were most likely triggered after a fluid pressure threshold had been exceeded.

  18. Unusual seismic signals associated with the activity at Galeras volcano, Colombia, from July 1992 to September 1994

    Directory of Open Access Journals (Sweden)

    L. Narvàez M.

    1996-06-01

    Full Text Available After the emplacement of a lava dome at Galeras volcano in 1991, seven eruptions occurred from July 16, 1992, to September 23, 1994, six of which were preceded by quasi-monochromatic, long-duration seismic events with slowly decaying coda named «tornillos» (screws. The dominant frequencies of these unusual seismic signals are related to source characteristics and show temporal changes, diminishing and then tending to stabilize before an eruption. At the same time, the accumulated number and the duration of these signals increase several days prior to the eruption. The increase in the duration of the tornillo events and the decline of the dominant frequencies both suggest an increasing impedance contrast between the surrounding solid material and the fluid. These characteristics may be associated with an increase in the free gas phase in the magma produced by saturation of volatiles due to cooling, crystallization and partial solidification of the column of magma plugging the conduits. The solidified magma can contribute to sealing the conduits and preventing free gas escape, with consequent generation of overpressure. An eruption is initiated when the overpressure exceeds the resistance strength of the solid material.

  19. Chiliques volcano, Chile

    Science.gov (United States)

    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 joint U

  20. Volcano-Monitoring Instrumentation in the United States, 2008

    Science.gov (United States)

    Guffanti, Marianne; Diefenbach, Angela K.; Ewert, John W.; Ramsey, David W.; Cervelli, Peter F.; Schilling, Steven P.

    2010-01-01

    The United States is one of the most volcanically active countries in the world. According to the global volcanism database of the Smithsonian Institution, the United States (including its Commonwealth of the Northern Mariana Islands) is home to about 170 volcanoes that are in an eruptive phase, have erupted in historical time, or have not erupted recently but are young enough (eruptions within the past 10,000 years) to be capable of reawakening. From 1980 through 2008, 30 of these volcanoes erupted, several repeatedly. Volcano monitoring in the United States is carried out by the U.S. Geological Survey (USGS) Volcano Hazards Program, which operates a system of five volcano observatories-Alaska Volcano Observatory (AVO), Cascades Volcano Observatory (CVO), Hawaiian Volcano Observatory (HVO), Long Valley Observatory (LVO), and Yellowstone Volcano Observatory (YVO). The observatories issue public alerts about conditions and hazards at U.S. volcanoes in support of the USGS mandate under P.L. 93-288 (Stafford Act) to provide timely warnings of potential volcanic disasters to the affected populace and civil authorities. To make efficient use of the Nation's scientific resources, the volcano observatories operate in partnership with universities and other governmental agencies through various formal agreements. The Consortium of U.S. Volcano Observatories (CUSVO) was established in 2001 to promote scientific cooperation among the Federal, academic, and State agencies involved in observatory operations. Other groups also contribute to volcano monitoring by sponsoring long-term installation of geophysical instruments at some volcanoes for specific research projects. This report describes a database of information about permanently installed ground-based instruments used by the U.S. volcano observatories to monitor volcanic activity (unrest and eruptions). The purposes of this Volcano-Monitoring Instrumentation Database (VMID) are to (1) document the Nation's existing

  1. The critical role of volcano monitoring in risk reduction

    Directory of Open Access Journals (Sweden)

    R. I. Tilling

    2008-01-01

    Full Text Available 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.

  2. Ups and downs on spreading flanks of ocean-island volcanoes: evidence from Mauna Loa and Kīlauea

    Science.gov (United States)

    Lipman, Peter W.; Eakins, Barry W.; Yokose, Hisayoshi

    2003-01-01

    Submarine-flank deposits of Hawaiian volcanoes are widely recognized to have formed largely by gravitationally driven volcano spreading and associated landsliding. Observations from submersibles show that prominent benches at middepths on flanks of Mauna Loa and Kilauea consist of volcaniclastic debris derived by landsliding from nearby shallow submarine and subaerial flanks of the same edifice. Massive slide breccias from the mature subaerial tholeiitic shield of Mauna Loa underlie the frontal scarp of its South Kona bench. In contrast, coarse volcaniclastic sediments derived largely from submarine-erupted preshield alkalic and transitional basalts of ancestral Kilauea underlie its Hilina bench. Both midslope benches record the same general processes of slope failure, followed by modest compression during continued volcano spreading, even though they record development during different stages of edifice growth. The dive results suggest that volcaniclastic rocks at the north end of the Kona bench, interpreted by others as distal sediments from older volcanoes that were offscraped, uplifted, and accreted to the island by far-traveled thrusts, alternatively are a largely coherent stratigraphic assemblage deposited in a basin behind the South Kona bench.

  3. Similarities between rivers and submarine channels

    Science.gov (United States)

    Balcerak, Ernie

    2013-02-01

    Scientists have long known that the width and depth of rivers follows a power law relationship with discharge. They have also noticed that submarine channels appear to be similar to terrestrial rivers, but there have not been many systematic comparisons of the relationships between submarine channel morphology and discharge. Konsoer et al. compared the width, depth, and slope of 177 submarine channels to those of 231 river cross sections. They found that submarine channels are up to an order of magnitude wider and deeper than the largest terrestrial rivers, but they exhibit a similar power law relationship between width and depth. For submarine channels that were similar in size to rivers, the authors found that submarine channels tend to be 1 to 2 orders of magnitude steeper than rivers. The authors also inferred values for sediment concentration in the turbidity currents in the channels and combined this with estimated mean flow velocities to look for a relationship between discharge and morphology in the channels. They found that like rivers, the width and depth of the submarine channels follow a power law scaling with discharge. (Journal of Geophysical Research-Earth Surface, doi:10.1029/2012JF002422, 2013)

  4. Mud Volcanoes from the Beaufort Sea to the South China Sea

    Science.gov (United States)

    Lundsten, E. M.; Paull, C. K.; Caress, D. W.; Dallimore, S.; Melling, H.; Liu, C. S.; Anderson, K.; Gwiazda, R.

    2015-12-01

    The detailed morphology of five submarine mud volcanoes were surveyed using an Autonomous Underwater Vehicle (AUV) developed at the Monterey Bay Aquarium Research Institute. Mud volcanoes are constructional features built by extrusion of gas, subsurface fluids and fine-grained sediment. Two surveys covering four submarine mud volcanoes were conducted on the CCGS Sir Wilfred Laurier in the Beaufort Sea in the Canadian Arctic. A survey of one mud volcano was conducted on the Taiwanese Ocean Research V in the South China Sea, SE of Taiwan. The AUV carried a multibeam sonar, a 1-6 kHz chirp sub-bottom profiler, and a110 kHz sidescan, and obtained overlapping multibeam bathymetric coverage at a vertical resolution of 0.15 m with a horizontal footprint of 0.9 m and chirp seismic-reflection profiles with a vertical resolution of 0.11 m. Mud volcanoes were either flat topped or conical. The conical mud volcano off Taiwan had a diameter of ~2 km and 10° side slopes; the conical feature in the Beaufort Sea had a diameter of ~1.5 km and 4° side slopes. The sides of the conical mud volcanoes were smooth, suggesting they were formed by sediment flows that emanate from a vent on their crests. The flanks of the conical mud volcanoes characteristically had very low acoustic reflectivity, but one single high reflectivity trail from the crest of the Beaufort Sea mud volcano indicates a recent flow. Three mud volcanoes in the Beaufort Sea formed circular, flat-topped plateaus that are up to ~1.1 km in diameter and elevated up to 30 m from the surrounding seafloor. The fine scale morphology and reflectivity on these plateaus show low relief, concentric, and ovoid circles that appear to be mud boils probably associated with eruptive events of varying ages at shifting vent sites. The different mud volcano shapes are attributed to variations in the viscosity of the erupting sediment slurries and may represent a sequential morphology, which is altered by shifts in venting position over

  5. Northern Arizona Volcanoes

    Science.gov (United States)

    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, 111.5 degrees West longitude

  6. Biological Studies on a Live Volcano.

    Science.gov (United States)

    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.…

  7. Cook Inlet and Kenai Peninsula, Alaska ESI: VOLCANOS (Volcano Points)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains the locations of volcanos in Cook Inlet and Kenai Peninsula, Alaska. Vector points in the data set represent the location of the volcanos....

  8. Boron and B Isotopes in Mud Volcanoes and Their Significance for Mobilization Depth and Global B Cycling

    Science.gov (United States)

    Kopf, A. J.; Deyhle, A.

    2001-12-01

    Mud volcanism is a global phenomenon in mostly convergent margin settings, whose nature has long been subject to scientific investigation. However, only recently its significance has been unravelled by quantitative studies in well-investigated submarine environments, like large acretionary complexes. The fluid flux through active mud volcanoes has been estimated to exceed that of the frontal accretionary prism (Kopf et al. 2001, EPSL 189, p295-313), and may have done so in earlier Earth`s history. Pore fluids as well as muds and clasts of onshore and offshore mud volcanoes all over the world have undergone a systematic geochemical study using contents and stable isotopes of the mobile element boron. When tied into results from hydrothermal geochemical experiments in the laboratory (You et al. 1996, EPSL 140, p41-52), the B geochemistry proofs to be a powerful tracer to estimate the depth of fluid and mud mobilization below ground. Boron adsorbed to clay minerals is preferably donated to the fluid when either tectonic stress (vertical and/or lateral compaction) or temperature increase. Here, we report variations in B content and B isotope ratios in mud volcano deposits as a result of different history of the material prior to extrusion. Results reflect the regional geology of the study areas, ranging from dewatering of undercompacted marine sediment in accretionary prisms (Barbados, Makran, Mediterranean Sea) to diagenetic reactions in mud volcanoes of orogenic belts (Malaysia, Pakistan, Georgia, Taman Peninsula, Western Alps). Boron shows maximum enrichment in the fluid phase (owing to desorption in the mud) when faulting roots deepest and deformation is strongest. Mud domes juxtaposing out-of-sequence faults in the Caucasus orogenic wedge show mud B contents 8x marine sediment, and fluid B contents up to 25x seawater. Deep-seated, B-rich fluids liquefy clay-bearing strata to facilitate mud extrusion, allowing the clay to re-adsorb B in the process. B isotopic

  9. Streamlining volcano-related, web-based data display and design with a new U.S. Geological Survey Volcano Science Center website

    Science.gov (United States)

    Stovall, W. K.; Randall, M. J.; Cervelli, P. F.

    2011-12-01

    The goal of the newly designed U.S. Geological Survey (USGS) Volcano Science Center website is to provide a reliable, easy to understand, and accessible format to display volcano monitoring data and scientific information on US volcanoes and their hazards. There are greater than 150 active or potentially active volcanoes in the United States, and the Volcano Science Center aims to advance the scientific understanding of volcanic processes at these volcanoes and to lessen the harmful impacts of potential volcanic activity. To fulfill a Congressional mandate, the USGS Volcano Hazards Program must communicate scientific findings to authorities and the public in a timely and understandable form. The easiest and most efficient way to deliver this information is via the Internet. We implemented a new database model to organize website content, ensuring consistency, accuracy, and timeliness of information display. Real-time monitoring data is available for over 50 volcanoes in the United States, and web-site visitors are able to interact with a dynamic, map-based display system to access and analyze these data, which are managed by scientists from the five USGS volcano observatories. Helicorders, recent hypocenters, webcams, tilt measurements, deformation, gas emissions, and changes in hydrology can be viewed for any of the real-time instruments. The newly designed Volcano Science Center web presence streamlines the display of research findings, hazard assessments, and real-time monitoring data for the U.S. volcanoes.

  10. Segmentation and tracking of anticyclonic eddies during a submarine volcanic eruption using ocean colour imagery.

    Science.gov (United States)

    Marcello, Javier; Eugenio, Francisco; Estrada-Allis, Sheila; Sangrà, Pablo

    2015-04-14

    The eruptive phase of a submarine volcano located 2 km away from the southern coast of El Hierro Island started on October 2011. This extraordinary event provoked a dramatic perturbation of the water column. In order to understand and quantify the environmental impacts caused, a regular multidisciplinary monitoring was carried out using remote sensing sensors. In this context, we performed the systematic processing of every MODIS and MERIS and selected high resolution Worldview-2 imagery to provide information on the concentration of a number of biological, physical and chemical parameters. On the other hand, the eruption provided an exceptional source of tracer that allowed the study a variety of oceanographic structures. Specifically, the Canary Islands belong to a very active zone of long-lived eddies. Such structures are usually monitored using sea level anomaly fields. However these products have coarse spatial resolution and they are not suitable to perform submesoscale studies. Thanks to the volcanic tracer, detailed studies were undertaken with ocean colour imagery allowing, using the diffuse attenuation coefficient, to monitor the process of filamentation and axisymmetrization predicted by theoretical studies and numerical modelling. In our work, a novel 2-step segmentation methodology has been developed. The approach incorporates different segmentation algorithms and region growing techniques. In particular, the first step obtains an initial eddy segmentation using thresholding or clustering methods and, next, the fine detail is achieved by the iterative identification of the points to grow and the subsequent application of watershed or thresholding strategies. The methodology has demonstrated an excellent performance and robustness and it has proven to properly capture the eddy and its filaments.

  11. Calciclastic submarine fans: An integrated overview

    Science.gov (United States)

    Payros, Aitor; Pujalte, Victoriano

    2008-01-01

    Calciclastic submarine fans are rare in the stratigraphic record and no bona fide present-day analogue has been described to date. Possibly because of that, and although calciclastic submarine fans have long intrigued deep-water carbonate sedimentologists, they have largely been overlooked by the academic and industrial communities. To fill this gap we have compiled and critically reviewed the existing sedimentological literature on calciclastic submarine fans, thus offering an updated view of this type of carbonate slope sedimentary system. Calciclastic submarine fans range in length from just a few to more than 100 km. Three different types can be distinguished: (1) Coarse-grained, small-sized (depression associated with tectonic structures, an inherited topography, or large-scale mass failures.

  12. Aspects of Propeller Developements for a Submarine

    DEFF Research Database (Denmark)

    Andersen, Poul; kappel, Jens Julius; Spangenberg, Eugen

    2009-01-01

    Design and development of propellers for submarines are in some ways different from propellers for surface vessels. The most important demand is low acoustic signature that has priority over propeller efficiency, and the submarine propeller must be optimized with respect to acoustics rather than...... efficiency. Moreover the operating conditions of a submarine propeller are quite different. These aspects are discussed as well as the weighing of the various propeller parameters against the design objectives. The noise generated by the propeller can be characterized as thrust noise due to the inhomogeneous...... wake field of the submarine, trailing-edge noise and noise caused by turbulence in the inflow. The items discussed are demonstrated in a case study where a propeller of the Kappel type was developed. Three stages of the development are presented, including a design of an 8-bladed propeller where...

  13. Russia's Submarine Force: Determinants and Prospects

    National Research Council Canada - National Science Library

    Tully, John

    2001-01-01

    ... the determinants of these events, The Russian Federation inherited a huge submarine fleet from the Soviet Union, Due to the changing conditions in the world and in Russia, its future status is in doubt...

  14. Geological implications of the 0212 earthquake in 2014 at the Tatun Volcano Group of Taiwan: Synergistic effects of volcanic and faulting activities

    Science.gov (United States)

    Pu, Hsin-Chieh; Lin, Cheng-Horng; Chang, Li-Chin; Kan, Chih-Wen; Lin, Che-Min; Li, Yi-Heng; Lai, Ya-Chuan; Shih, Min-Hung

    2017-11-01

    On February 12, 2014, an ML 4.2 earthquake (named 0212 EQ) occurred at the Tatun Volcano Group (TVG) in northern Taiwan. Seismic data from both the regional broadband array in Taiwan and a local dense seismic network in the TVG indicate that the 0212 EQ was located at a depth of 4.3 km near Shamoshan, one of the latest eruptive units in the TVG. Referring to the aftershocks surrounding the 0212 EQ, we further found that (1) they formed a linear seismic zone dipping ∼50° towards the southeast to reach the Shanchiao Fault that cuts through the TVG, (2) focal mechanism of more than half of the larger aftershocks (MD ≥ 1.5) matched this linear seismic zone for a normal faulting, and (3) the seismic b-value was calculated to be 3.55. They are used to delineate the geometry of the Shanchiao Fault at the upper crust and to infer that localized geothermal fluid might have affected the activity of aftershocks as manifested by the very high seismic b-value. The strongly compensated linear vector dipole of the centroid moment tensor suggests the 0212 EQ had a non-double-couple source resulted from the gravitational collapse. Thus, we conclude that the 0212 EQ was a combined synergistic effect of a collapsed reservoir filled with volcanic fluids and faulting activities along the Shanchiao Fault.

  15. Variations in archaeal and bacterial diversity associated with the anaerobic oxidation of methane in the active mud volcanoes of the Canadian Beaufort Sea

    Science.gov (United States)

    Lee, Y. M.; Lee, D. H.; Hwang, K.; Hong, S. G.; Jin, Y. K.

    2016-12-01

    The prokaryotic microorganisms inhabiting Mud Volcanoes (MVs) play an important role for mitigation of methane (CH4) emission. Despite the identification of active MVs in the continental slope of the Canadian Beaufort Sea, little is known about the distribution and functions of prokaryotic community in this region. Hence, we investigated the prokaryotic diversity of four sediment cores (three from the active MVs and one from a non-methane influenced reference site) of the Canadian Beaufort Sea using 454-pyrosequencing of 16S rRNA genes as the first step to understand the prokaryotic roles in controlling outgassing methane. Bacterial and archaeal communities of MVs were distinctive from those of the reference site, and the communities of MVs were similar to each other at deeper depth levels. Chloroflexi, Actinobacteria, unclassified bacterial groups, and MCG_c of Crenarchaeota were predominant in the MVs, while Firmicutes, Deltaproteobacteria, and unclassified class of Thaumarchaeota were dominant in reference site. The relative abundance of dominant bacterial groups varied at sulfate-methane transition zone (SMTZ) of individual MVs. However, certain microbial taxa such as members of SAGMEG_o or Methanosarcinales of Euryarcheaota and Dehalococcoidales of Chloroflexi were predominant at SMTZs. Since they are not the classical representative taxa known to be involved in anaerobic oxidation of methane, their dominance implicates that they could be playing important roles in methane cycling using unrevealed mechanisms. We will further perform the phylogenetic and network analyses to infer mechanisms and interactions of dominant operational taxonomic units in controlling methane flux.

  16. Alaska Volcano Observatory at 20

    Science.gov (United States)

    Eichelberger, J. C.

    2008-12-01

    research opportunities for Russian and American students. AVO was a three-way partnership of the federal and state geological surveys and the state university from the start. This was not a flowering of ecumenism but was rather at the insistence of the Alaska congressional delegation. Such shared enterprises are not managerially convenient, but they do bring a diversity of roles, thinking, and expertise that would not otherwise be possible. Through AVO, the USGS performs its federally mandated role in natural hazard mitigation and draws on expertise available from its network of volcano observatories. The Alaska Division of Geological and Geophysical Surveys performs a similar role at the state level and, in the tradition of state surveys, provides important public communications, state data base, and mapping functions. The University of Alaska Fairbanks brought seismological, remote sensing, geodetic, petrological, and physical volcanological expertise, and uniquely within US academia was able to engage students directly in volcano observatory activities. Although this "model" cannot be adopted in total elsewhere, it has served to point the USGS Volcano Hazards Program in a direction of greater openness and inclusiveness.

  17. Experimental studies of anomalous radon activity in the Tlamacas Mountain, Popocatepetl Volcano area, México: new tools to study lithosphere-atmosphere coupling for forecasting volcanic and seismic events

    Directory of Open Access Journals (Sweden)

    Jose Antonio Lopez Cruz Abeyro

    2012-04-01

    Full Text Available

    This study presents and discusses the results of soil radon monitoring at three different volcano sites and one reference site, from December 2007 to January 2009. This relates to the activity of the Popocatepetl Volcano and a radon survey and gamma-ray spectrometry in the area between Paso de Cortes and Tlamacas Mountain, and in the adjacent regions. The results are applied to the aspects of atmosphere electricity and lithosphere-atmosphere coupling in relation to the forecasting of volcano and earthquake activity. The monitoring of radon release reveals a decrease in radon concentration (down to total suppression with approaching moderate volcanic eruptions. The behavior of the radon activity at the Tlamacas site is more apparent, compared to other observational sites. The average level of radon release observed at the Tlamacas site is much higher, with some characteristic variations. Both the radon survey and gamma-ray spectrometry indicate intensive diffusion radon emission localized in the area of Tlamacas Mountain. The average radon concentration in the area of Tlamacas is about 10-20-fold greater than the background volcano values. The new concept of lithosphere-atmosphere coupling is presented: intensive radon release in high elevated areas shortens and modifies the Earth-to-thunderclouds electric circuit, which provokes microdischarges into the air close to the ground, attracting lightning discharges. This concept attempts to explain in a new way the noise-like geomagnetic emissions registered before major earthquakes, and it promotes interest for the study of thunderstorm activity in seismo-active zones, as a promising instrument for earthquake forecasting.

  18. SSN 774 Virginia Class Submarine (SSN 774)

    Science.gov (United States)

    2015-12-01

    Report: The VIRGINIA Class Submarine Program continues to deliver submarines within cost, ahead of schedule , with improved quality and with...baseline schedule threshold set ten years earlier, in 1994. June 20, 2006: USS TEXAS, which was essentially the second lead ship of the class , is the first...factored for the VIRGINIA Class based on weight. Public and private shipyard data was used, as well as the maintenance schedule provided in the CARD, Rev E

  19. ROV Tiburon Investigation of Hawaiian Submarine Canyons

    Science.gov (United States)

    Paull, C. K.; Greene, H. G.; Caress, D. W.; Clague, D. A.; Ussler, W.; Maher, N. M.

    2001-12-01

    MBARI conducted ROV dives around the Hawaiian Islands during an expedition of the R/V Western Flyer and Tiburon in the spring of 2001. Eight ROV dives were made to investigate five major submarine canyons offshore of Oahu, Molokai, and Hawaii in up to 3,434 m water depths. Four of these canyons are located off the windward (northern) side of these islands where onshore canyons are also well developed. Those canyons located offshore of Molokai and Oahu incise the head scars of the giant Nuuanu and Wailai submarine landslides. ROV observations and sediment and rock outcrop sampling were made in these canyons to determine their origin and present-day activity. The fifth canyon investigated is located on the leeward (southern) side of Molokai. The canyons along the windward side expose extensive stratigraphic sections that reveal the history of the islands' formation. In composite, these sections contain marine pillow basalt overlain by a substantial sequence of alternating subaerial lava flows, rounded boulder conglomerates, shallow water carbonates, and hyaloclastites that indicate coastal and marine deposition. These sequences illustrate the accretion and subsequent subsidence of the islands' flanks. These canyons also have morphologically distinct upper and lower sections. The upper reaches of the canyons are incised into the shallow water marine facies and contain broad axial channels through which active sediment transport is occurring. In contrast, the morphology of the lower canyons are strongly influenced by the giant landslides that massively altered the northern flanks of the Hawaiian chain. The lower canyons contain plunge pools and steep headwall scarps that are generally comprised of mechanically competent subaerial lava flows. The presence of multiple plunge pools with differentially eroded head scarps suggests retrogressive erosion (bottom-up process) with headward advancement of the various heads. Undercutting of the headwalls also produce periodic

  20. Preliminary volcano-hazard assessment for Akutan Volcano east-central Aleutian Islands, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Power, John A.; Richter, Donlad H.; McGimsey, Robert G.

    1998-01-01

    Akutan Volcano is a 1100-meter-high stratovolcano on Akutan Island in the east-central Aleutian Islands of southwestern Alaska. The volcano is located about 1238 kilometers southwest of Anchorage and about 56 kilometers east of Dutch Harbor/Unalaska. Eruptive activity has occurred at least 27 times since historical observations were recorded beginning in the late 1700?s. Recent eruptions produced only small amounts of fine volcanic ash that fell primarily on the upper flanks of the volcano. Small amounts of ash fell on the Akutan Harbor area during eruptions in 1911, 1948, 1987, and 1989. Plumes of volcanic ash are the primary hazard associated with eruptions of Akutan Volcano and are a major hazard to all aircraft using the airfield at Dutch Harbor or approaching Akutan Island. Eruptions similar to historical Akutan eruptions should be anticipated in the future. Although unlikely, eruptions larger than those of historical time could generate significant amounts of volcanic ash, fallout, pyroclastic flows, and lahars that would be hazardous to life and property on all sectors of the volcano and other parts of the island, but especially in the major valleys that head on the volcano flanks. During a large eruption an ash cloud could be produced that may be hazardous to aircraft using the airfield at Cold Bay and the airspace downwind from the volcano. In the event of a large eruption, volcanic ash fallout could be relatively thick over parts of Akutan Island and volcanic bombs could strike areas more than 10 kilometers from the volcano.

  1. Submarine landslides: processes, triggers and hazard prediction.

    Science.gov (United States)

    Masson, D G; Harbitz, C B; Wynn, R B; Pedersen, G; Løvholt, F

    2006-08-15

    Huge landslides, mobilizing hundreds to thousands of km(3) of sediment and rock are ubiquitous in submarine settings ranging from the steepest volcanic island slopes to the gentlest muddy slopes of submarine deltas. Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential. The major hazards related to submarine landslides include destruction of seabed infrastructure, collapse of coastal areas into the sea and landslide-generated tsunamis. Most submarine slopes are inherently stable. Elevated pore pressures (leading to decreased frictional resistance to sliding) and specific weak layers within stratified sequences appear to be the key factors influencing landslide occurrence. Elevated pore pressures can result from normal depositional processes or from transient processes such as earthquake shaking; historical evidence suggests that the majority of large submarine landslides are triggered by earthquakes. Because of their tsunamigenic potential, ocean-island flank collapses and rockslides in fjords have been identified as the most dangerous of all landslide related hazards. Published models of ocean-island landslides mainly examine 'worst-case scenarios' that have a low probability of occurrence. Areas prone to submarine landsliding are relatively easy to identify, but we are still some way from being able to forecast individual events with precision. Monitoring of critical areas where landslides might be imminent and modelling landslide consequences so that appropriate mitigation strategies can be developed would appear to be areas where advances on current practice are possible.

  2. Pockmark morphology and turbulent buoyant plumes at a submarine spring

    Science.gov (United States)

    Buongiorno Nardelli, B.; Budillon, F.; Watteaux, R.; Ciccone, F.; Conforti, A.; De Falco, G.; Di Martino, G.; Innangi, S.; Tonielli, R.; Iudicone, D.

    2017-09-01

    The input flow of groundwater from the seabed to the coastal ocean, known as Submarine Groundwater Discharge (SGD), has been only recently recognized as an important component of continental margin systems. It potentially impacts physical, chemical and biological marine dynamics. Independently of its specific nature (seepage, submarine springs, etc.) or fluid chemical composition, a SGD is generally characterized by low flow rates, hence making its detection and quantification very difficult, and explaining why it has been somewhat neglected by the scientific community for a long time. Along with the growing interest for SGDs emerged the need for in-situ observations in order to characterize in details how these SGDs behave. In this work, we describe the morphology of a pockmark field, detected in the Southern Tyrrhenian Sea (Mediterranean Sea), and provide observational evidences of the presence of active submarine springs over the coastal shelf area. We describe the effect of the fluid seeps on the water column stratification close to the main plumes and in the neighbouring areas, providing quantitative estimates of the intensity of the turbulent mixing and discussing their potential impact on the seabed morphology and pockmark formation in the context of turbulent buoyant plumes analytical modelling.

  3. Organizational changes at Earthquakes & Volcanoes

    Science.gov (United States)

    Gordon, David W.

    1992-01-01

    Primary responsibility for the preparation of Earthquakes & Volcanoes within the Geological Survey has shifted from the Office of Scientific Publications to the Office of Earthquakes, Volcanoes, and Engineering (OEVE). As a consequence of this reorganization, Henry Spall has stepepd down as Science Editor for Earthquakes & Volcanoes(E&V).

  4. Submarine landslide and tsunami hazards offshore southern Alaska: Seismic strengthening versus rapid sedimentation

    Science.gov (United States)

    Sawyer, Derek E.; Reece, Robert S.; Gulick, Sean P. S.; Lenz, Brandi L.

    2017-08-01

    The southern Alaskan offshore margin is prone to submarine landslides and tsunami hazards due to seismically active plate boundaries and extreme sedimentation rates from glacially enhanced mountain erosion. We examine the submarine landslide potential with new shear strength measurements acquired by Integrated Ocean Drilling Program Expedition 341 on the continental slope and Surveyor Fan. These data reveal lower than expected sediment strength. Contrary to other active margins where seismic strengthening enhances slope stability, the high-sedimentation margin offshore southern Alaska behaves like a passive margin from a shear strength perspective. We interpret that seismic strengthening occurs but is offset by high sedimentation rates and overpressure. This conclusion is supported by shear strength outside of the fan that follow an active margin trend. More broadly, seismically active margins with wet-based glaciers are susceptible to submarine landslide hazards because of the combination of high sedimentation rates and earthquake shaking.

  5. Impact of tephra falls on Andean communities: The influences of eruption size and weather conditions during the 1999-2001 activity of Tungurahua volcano, Ecuador

    Science.gov (United States)

    Le Pennec, Jean-Luc; Ruiz, Gorki A.; Ramón, Patricio; Palacios, Enrique; Mothes, Patricia; Yepes, Hugo

    2012-03-01

    Repeated ash fall events have occurred during the 1999-ongoing eruption of Tungurahua volcano, Ecuador, notably during the late 1999 and August 2001 eruptive phases. While the eruptive styles were similar, these two phases had different impacts on nearby rural and urban Andean populations: ash falls in late 1999 had limited effects on human health and farming, whereas the 2001 phase resulted in medical problems, death of animals in livestock, and damages to houses and crops. Here we investigate the origin of this difference by estimating the size of the August 2001 event (VEI, magnitude, intensity), and by comparing monitoring information of the 1999 and 2001 phases (duration, explosion rate, column height, SO2 output rate). The results show that both phases ranked at VEI 3, although the longer 1999 phase was likely larger than the 2001 phase. Mass magnitude (M) and intensity (I) indexes calculated for the 2001 phase reach M ≈ 2.7 and I ≈ 6.5 when based on ash fall layer data, but increase to M ≈ 3.2 and I ≈ 7.0 when ballistic products are included. We investigated the influence of rain fall and wind flow regimes on ash dispersion, sedimentation and remobilization. The analysis indicates that the harmful effect of the 2001 phase resulted from unfavorable conditions that combined volcanological and seasonal origins, including: a) a low elevation of the ash plume above rural regions owed to a usually bent-over column, b) ash sedimentation in a narrow area west of the volcano under sub-steady wind directions, c) anticipated ash settling by frequent rain flushing of low intensity, and d) formation of a wet cohesive ash coating on buildings and harvests. Conversely, the stronger 1999 phase injected a large amount of ash at higher elevation in the dry season; the ash was widely disseminated across the whole Ecuadorian territory and beyond, and was frequently removed by rain and winds. In summary, our study illustrates the influences of eruption size and weather

  6. The origin of the Hawaiian Volcano Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Dvorak, John [University of Hawaii' s Institute for Astronomy (United States)

    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. Volcano-electromagnetic effects

    Science.gov (United States)

    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.

  8. Translating Volcano Hazards Research in the Cascades Into Community Preparedness

    Science.gov (United States)

    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.

  9. Deformation Study of Papandayan Volcano using GPS Survey Method and Its Correlation with Seismic Data Observation

    Directory of Open Access Journals (Sweden)

    Dina A. Sarsito

    2006-11-01

    Full Text Available Papandayan volcano located in the southern part of Garut regency, around 70 km away from Bandung city, West Java. Many methods carried out to monitoring the activities of volcano, both continuously or periodically, one of the monitoring method is periodically GPS survey. Basically those surveys are carried out to understand the pattern and velocity of displacement which occurred in the volcano body, both horizontally and vertically, and also others deformation elements such as; translation, rotation and dilatation. The Mogi modeling was also used to determine the location and volume of the pressure source which caused deformation of volcano body. By comparing seismic activity and the deformation reveal from GPS measurement, before, during and after eruption, it could be understood there is a correlation between the seismicity and its deformation. These studies is hoping that GPS measurement in Papandayan volcano could be one of supported method to determine the volcano activities, at least in Papandayan volcano.

  10. Geomorphological and geochemical characterization of the 11 August 2008 mud volcano eruption at S. Barbara village (Sicily, Italy) and its possible relationship with seismic activity

    Science.gov (United States)

    Madonia, P.; Grassa, F.; Cangemi, M.; Musumeci, C.

    2011-05-01

    On 11 August 2008 a paroxysmal eruption occurred at Santa Barbara mud volcano (MV), located close to Caltanissetta, one of the most densely populated cities of Sicily (Italy). An associated minor event took place on August 2009. Both the events caused severe damage to civil infrastructures located within a range of about 2 km from the eruptive vent. Geomorphological, geochemical, and seismological investigations were carried out for framing the events in the appropriate geodynamic context. Geomorphological surveys recognized, in the immediate surrounding of the main emission point, two different families of processes and landforms: (i) ground deformations and (ii) changes in morphology and number of the fluid emitting vents. These processes were associated to a wider network of fractures, seemingly generated by the shock wave produced by the gas blast that occurred at the main paroxysm. Geochemical characterization allowed an estimation of the source of the fluids, or at least their last standing, at about 3 km depth. Finally, the close time relationships observed between anomalous increments of seismic activity and the two main paroxysmal events accounted for a possible common trigger for both the phenomena, even with different timing due to the very different initial conditions and characteristics of the two processes, i.e. seismogenesis and gas overloading.

  11. Geomorphological and geochemical characterization of the 11 August 2008 mud volcano eruption at S. Barbara village (Sicily, Italy and its possible relationship with seismic activity

    Directory of Open Access Journals (Sweden)

    P. Madonia

    2011-05-01

    Full Text Available On 11 August 2008 a paroxysmal eruption occurred at Santa Barbara mud volcano (MV, located close to Caltanissetta, one of the most densely populated cities of Sicily (Italy. An associated minor event took place on August 2009. Both the events caused severe damage to civil infrastructures located within a range of about 2 km from the eruptive vent. Geomorphological, geochemical, and seismological investigations were carried out for framing the events in the appropriate geodynamic context. Geomorphological surveys recognized, in the immediate surrounding of the main emission point, two different families of processes and landforms: (i ground deformations and (ii changes in morphology and number of the fluid emitting vents. These processes were associated to a wider network of fractures, seemingly generated by the shock wave produced by the gas blast that occurred at the main paroxysm. Geochemical characterization allowed an estimation of the source of the fluids, or at least their last standing, at about 3 km depth. Finally, the close time relationships observed between anomalous increments of seismic activity and the two main paroxysmal events accounted for a possible common trigger for both the phenomena, even with different timing due to the very different initial conditions and characteristics of the two processes, i.e. seismogenesis and gas overloading.

  12. Soft sediment deformation structures in a lacustrine sedimentary succession induced by volcano-tectonic activities: An example from the Cretaceous Beolgeumri Formation, Wido Volcanics, Korea

    Science.gov (United States)

    Ko, Kyoungtae; Kim, Sung Won; Lee, Hong-Jin; Hwang, In Gul; Kim, Bok Chul; Kee, Won-Seo; Kim, Young-Seog; Gihm, Yong Sik

    2017-08-01

    syndepositional magmatic activities, as is the case for modern tectonic earthquakes around active volcanoes.

  13. Volcano hazards program in the United States

    Science.gov (United States)

    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

  14. Applications of geophysical methods to volcano monitoring

    Science.gov (United States)

    Wynn, Jeff; Dzurisin, Daniel; Finn, Carol A.; Kauahikaua, James P.; Lahusen, Richard G.

    2006-01-01

    The array of geophysical technologies used in volcano hazards studies - some developed originally only for volcano monitoring - ranges from satellite remote sensing including InSAR to leveling and EDM surveys, campaign and telemetered GPS networks, electronic tiltmeters and strainmeters, airborne magnetic and electromagnetic surveys, short-period and broadband seismic monitoring, even microphones tuned for infrasound. They include virtually every method used in resource exploration except large-scale seismic reflection. By “geophysical ” we include both active and passive methods as well as geodetic technologies. Volcano monitoring incorporates telemetry to handle high-bandwith cameras and broadband seismometers. Critical geophysical targets include the flux of magma in shallow reservoir and lava-tube systems, changes in active hydrothermal systems, volcanic edifice stability, and lahars. Since the eruption of Mount St. Helens in Washington State in 1980, and the eruption at Pu’u O’o in Hawai’i beginning in 1983 and still continuing, dramatic advances have occurred in monitoring technology such as “crisis GIS” and lahar modeling, InSAR interferograms, as well as gas emission geochemistry sampling, and hazards mapping and eruption predictions. The on-going eruption of Mount St. Helens has led to new monitoring technologies, including advances in broadband Wi-Fi and satellite telemetry as well as new instrumentation. Assessment of the gap between adequate monitoring and threat at the 169 potentially dangerous Holocene volcanoes shows where populations are dangerously exposed to volcanic catastrophes in the United States and its territories . This paper focuses primarily on Hawai’ian volcanoes and the northern Pacific and Cascades volcanoes. The US Geological Survey, the US National Park System, and the University of Utah cooperate in a program to monitor the huge Yellowstone volcanic system, and a separate observatory monitors the restive Long Valley

  15. Westward advance of the deformation front and evolution of submarine canyons offshore of southwestern Taiwan

    Science.gov (United States)

    Han, Wei-Chung; Liu, Char-Shine; Chi, Wu-Cheng; Chen, Liwen; Lin, Che-Chuan; Chen, Song-Chuen

    2017-11-01

    This study analyzes both 2D and 3D seismic images around the Palm Ridge area offshore of southwestern Taiwan to understand how the deformation front shifted westward and how tectonic activities interact with submarine canyon paths in the transition area between the active and passive margins. Palm Ridge is a submarine ridge that developed on the passive China continental margin by down-dip erosion of several tributaries of Penghu Canyon; it extends eastward across the deformation front into the submarine Taiwan accretionary wedge. The presence of proto-thrusts that are located west of the frontal thrust implies that the compressional stress field has advanced westward due to the convergence of the Philippine Sea Plate and Eurasian Plate. Since the deformation front is defined as the location of the most frontal contractional structure, no significant contractional structure should appear west of it. We thus suggest moving the location of the previously mapped deformation front farther west to where the westernmost proto-thrust lies. High-resolution seismic and bathymetric data reveal that the directions of the paleo-submarine canyons run transverse to the present slope dip, while the present submarine canyons head down slope in the study area. We propose that this might be the result of the westward migration of the deformation front that changed the paleo-bathymetry and thus the canyon path directions. The interactions of down-slope processes and active tectonics control the canyon paths in our study area.

  16. ASTER Images Mt. Usu Volcano

    Science.gov (United States)

    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 miles

  17. Scientific Ocean Drilling to Assess Submarine Geohazards along European Margins

    Science.gov (United States)

    Ask, M. V.; Camerlenghi, A.; Kopf, A.; Morgan, J. K.; Ocean DrillingSeismic Hazard, P. E.

    2008-12-01

    Submarine geohazards are some of the most devastating natural events in terms of lives lost and economic impact. Earthquakes pose a big threat to society and infrastructure, but the understanding of their episodic generation is incomplete. Tsunamis are known for their potential of striking coastlines world-wide. Other geohazards originating below the sea surface are equally dangerous for undersea structures and the coastal population: submarine landslides and volcanic islands collapse with little warning and devastating consequences. The European scientific community has a strong focus on geohazards along European and nearby continental margins, especially given their high population densities, and long historic and prehistoric record of hazardous events. For example, the Mediterranean is surrounded by very densely-populated coastline and is the World's leading holiday destination, receiving up 30% of global tourism. In addition, its seafloor is criss-crossed by hydrocarbon pipelines and telecommunication cables. However, the governing processes and recurrence intervals of geohazards are still poorly understood. Examples include, but are not limited to, earthquakes and volcanic eruptions along the active tectonic margins of the Mediterranean and Sea of Marmara, landslides on both active and passive margins, and tsunamites and seismites in the sedimentary record that suggest a long history of similar events. The development of geophysical networks, drilling, sampling and long-term monitoring are crucial to the understanding of earthquake, landslide, and tsunami processes, and to mitigate the associated risks in densely populated and industrialized regions such as Europe. Scientific drilling, particularly in the submarine setting, offers a unique tool to obtain drill core samples, borehole measurements and long-term observations. Hence, it is a critical technology to investigate past, present, and possible future influences of hazardous processes in this area. The

  18. Global Volcano Model

    Science.gov (United States)

    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.

  19. Analysis of the activity pattern of volcanoes through self-organized crack networks: The effect of density barriers—An application to Vesuvius activity in the period 1631-1944

    Science.gov (United States)

    Piegari, E.; Di Maio, R.; Scandone, R.

    2013-06-01

    We simulated the pattern of activity of a strato-volcano by using a cellular automaton model where magma is allowed to ascend to the surface through self-organized crack networks. Magma rises toward the surface by filling connected paths of fractures until the magma's density is less than that of surrounding rocks. If magma enters a region with negative or neutral buoyancy, it cools and solidifies; as a result, the local density profile is modified, and magmatic dikes are formed. We simulated the temporal evolution of high-density pathways of dikes that magma may eventually utilize to reach the surface. We showed that if a shallow neutral-negative buoyancy zone is restored after eruptions, due to, for example, piecemeal or chaotic collapses, a characteristic timescale appears in the inter-event repose time distribution. Such characteristic repose time represents the average time that magma takes to form a high-density pathway through the less dense rock layer, and it may give a hint to predict possible eruptive scenarios. Even if the model includes many simplifying assumptions in the definition of magma-rock interaction, the results obtained from simulations are consistent with the eruptive behavior of the Mt. Somma-Vesuvius volcano for the 1631-1944 period.

  20. Submarine Landslides at Santa Catalina Island, California

    Science.gov (United States)

    Legg, M. R.; Francis, R. D.

    2011-12-01

    Santa Catalina Island is an active tectonic block of volcanic and metamorphic rocks originally exposed during middle Miocene transtension along the evolving Pacific-North America transform plate boundary. Post-Miocene transpression created the existing large pop-up structure along the major strike-slip restraining bend of the Catalina fault that forms the southwest flank of the uplift. Prominent submerged marine terraces apparent in high-resolution bathymetric maps interrupt the steep submarine slopes in the upper ~400 meters subsea depths. Steep subaerial slopes of the island are covered by Quaternary landslides, especially at the sea cliffs and in the blueschist metamorphic rocks. The submarine slopes also show numerous landslides that range in area from a few hectares to more than three sq-km (300 hectares). Three or more landslides of recent origin exist between the nearshore and first submerged terrace along the north-facing shelf of the island's West End. One of these slides occurred during September 2005 when divers observed a remarkable change in the seafloor configuration after previous dives in the area. Near a sunken yacht at about 45-ft depth where the bottom had sloped gently into deeper water, a "sinkhole" had formed that dropped steeply to 100-ft or greater depths. Some bubbling sand was observed in the shallow water areas that may be related to the landslide process. High-resolution multibeam bathymetry acquired in 2008 by CSU Monterey Bay show this "fresh" slide and at least two other slides of varying age along the West End. The slides are each roughly 2 hectares in area and their debris aprons are spread across the first terrace at about 85-m water depth that is likely associated with the Last Glacial Maximum sealevel lowstand. Larger submarine slides exist along the steep Catalina and Catalina Ridge escarpments along the southwest flank of the island platform. A prominent slide block, exceeding 3 sq-km in area, appears to have slipped more than

  1. Anatomy of a volcano

    NARCIS (Netherlands)

    Hooper, A.; Wassink, J.

    2011-01-01

    The Icelandic volcano Eyjafjallajökull caused major disruption in European airspace last year. According to his co-author, Freysteinn Sigmundsson, the reconstruction published in Nature six months later by aerospace engineering researcher, Dr Andy Hooper, opens up a new direction in volcanology. “We

  2. Submarine landslides of the Southern California Borderland

    Science.gov (United States)

    Lee, H.J.; Greene, H. Gary; Edwards, B.D.; Fisher, M.A.; Normark, W.R.

    2009-01-01

    Conventional bathymetry, sidescan-sonar and seismic-reflection data, and recent, multibeam surveys of large parts of the Southern California Borderland disclose the presence of numerous submarine landslides. Most of these features are fairly small, with lateral dimensions less than ??2 km. In areas where multibeam surveys are available, only two large landslide complexes were identified on the mainland slope- Goleta slide in Santa Barbara Channel and Palos Verdes debris avalanche on the San Pedro Escarpment south of Palos Verdes Peninsula. Both of these complexes indicate repeated recurrences of catastrophic slope failure. Recurrence intervals are not well constrained but appear to be in the range of 7500 years for the Goleta slide. The most recent major activity of the Palos Verdes debris avalanche occurred roughly 7500 years ago. A small failure deposit in Santa Barbara Channel, the Gaviota mudflow, was perhaps caused by an 1812 earthquake. Most landslides in this region are probably triggered by earthquakes, although the larger failures were likely conditioned by other factors, such as oversteepening, development of shelf-edge deltas, and high fluid pressures. If a subsequent future landslide were to occur in the area of these large landslide complexes, a tsunami would probably result. Runup distances of 10 m over a 30-km-long stretch of the Santa Barbara coastline are predicted for a recurrence of the Goleta slide, and a runup of 3 m over a comparable stretch of the Los Angeles coastline is modeled for the Palos Verdes debris avalanche. ?? 2009 The Geological Society of America.

  3. Introduction - The impacts of the 2008 eruption of Kasatochi Volcano on terrestrial and marine ecosystems in the Aleutian Islands, Alaska

    Science.gov (United States)

    DeGange, Anthony R.; Byrd, G. Vernon; Walker, Lawrence R.; Waythomas, C.F.

    2010-01-01

    The Aleutian Islands are situated on the northern edge of the so-called “Pacific Ring of Fire,” a 40,000-km-long horseshoe-shaped assemblage of continental landmasses and islands bordering the Pacific Ocean basin that contains many of the world's active and dormant volcanoes. Schaefer et al. (2009) listed 27 historically active volcanoes in the Aleutian Islands, of which nine have had at least one major eruptive event since 1990. Volcanic eruptions are often significant natural disturbances, and ecosystem responses to volcanic eruptions may vary markedly with eruption style (effusive versus explosive), frequency, and magnitude of the eruption as well as isolation of the disturbed sites from potential colonizing organisms (del Moral and Grishin, 1999). Despite the relatively high frequency of volcanic activity in the Aleutians, the response of island ecosystems to volcanic disturbances is largely unstudied because of the region's isolation. The only ecological studies in the region that address the effects of volcanic activity were done on Bogoslof Island, a remote, highly active volcanic island in the eastern Aleutians, which grew from a submarine eruption in 1796 (Merriam, 1910; Byrd et al., 1980; Byrd and Williams, 1994). Nevertheless, in the 214 years of Bogoslof's existence, the island has been visited only intermittently.Kasatochi Island is a small (2.9 km by 2.6 km, 314 m high) volcano in the central Aleutian Islands of Alaska (52.17°N latitude, 175.51°W longitude; Fig. 1) that erupted violently on 7-8 August 2008 after a brief, but intense period of precursory seismic activity (Scott et al., 2010 [this issue]; Waythomas et al., in review). The island is part of the Aleutian arc volcanic front, and is an isolated singular island. Although the immediate offshore areas are relatively shallow (20–50 m water depth), the island is about 10 km south of the 2000 m isobath, north of which, ocean depths increase markedly. Kasatochi is located between the

  4. Geophysical monitoring of the Purace volcano, Colombia

    Directory of Open Access Journals (Sweden)

    M. Arcila

    1996-06-01

    Full Text Available Located in the extreme northwestern part of the Los Coconucos volcanic chain in the Central Cordillera, the Purace is one of Colombia's most active volcanoes. Recent geological studies indicate an eruptive history of mainly explosive behavior which was marked most recently by a minor ash eruption in 1977. Techniques used to forecast the renewal of activity of volcanoes after a long period of quiescence include the monitoring of seismicity and ground deformation near the volcano. As a first approach toward the monitoring of the Purace volcano, Southwest Seismological Observatory (OSSO, located in the city of Cali, set up one seismic station in 1986. Beginning in June 1991, the seismic signals have also been transmitted to the Colombian Geological Survey (INGEOMINAS at the Volcanological and Seismological Observatory (OVS-UOP, located in the city of Popayan. Two more seismic stations were installed early in 1994 forming a minimum seismic network and a geodetic monitoring program for ground deformation studies was established and conducted by INGEOMINAS.

  5. Eruption history of the Tharsis shield volcanoes, Mars

    Science.gov (United States)

    Plescia, J. B.

    1993-01-01

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

  6. A Precursory Phase to a Sudden Enhanced Activity at Yasur volcano (Vanuatu) : Insights from Simultaneous Infrasonic and Seismic Records

    Science.gov (United States)

    Vergniolle, S.; Zielinski, C.; Battaglia, J.; Metaxian, J. P.; Bani, P.; LE Pichon, A.; Lardy, M.; Millier, P.; Frogneux, M.; Gallois, F.; Herry, P.; Todman, S.; Garaebiti, E.

    2015-12-01

    The permanent activity at Yasur (Vanuatu), characterised by a close series of Strombolian explosions, is analysed using simultaneous infrasonic and seismic recordings (6-25 Nov 2008) close to the vents. The RMS amplitudes per hour, the number of explosions and the peak-to-peak amplitudes of each signal show that the initial quiet phase (11 days) is followed by a precursory phase (7 days) prior to an enhanced activity (17 hours). Three periods exist during the strong activity: (1) a rapid increase leading to the paroxysm (3 hours), (2) a first (5 hours) and (3) a second decrease (9 hours), each having an excellent correlation between seismic and infrasonic RMS amplitudes per hour (correlation coefficient > 0.96) when using the band associated to explosions (1-5 Hz and 1.8-4 Hz for seismic and infrsonic recordings, respectively). The ratio between infrasonic and seismic RMS amplitudes, assumed to be a proxy for the magma level, increases strongly during the week before the paroxysm. This is explained by the arrival of an additional gas flux at the top of the reservoir. The foam accumulated there, whose partial coalescence and spreading towards the conduit are responsible for the permanent Strombolian activity, thickens. This enhances both the viscous massive foam coalescence and the foam spreading. This leads to an increase in the gas flux in the conduit, ultimately responsible for the formation of a shallow foam at the surface. This foam acts as a viscous cap overlying the magma column, thereby increasing the radiated infrasonic pressure and the strength of the explosions. The first decrease in the relationship between infrasonic and seismic RMS amplitudes is associated with the stopping of the additionnal gas flux in the magma reservoir and the rapid decrease of the top of the magma column due to the previous intense degassing. The second decrease corresponds to the time neccessary to restore the convective motions in the conduit at their normal velocities.

  7. Submarine Ground Water Discharge and Fate Along the Coast of Kaloko-Honokohau National Historical Park, Hawai'i:Part 2, Spatial and Temporal Variations in Salinity, Radium-Isotope Activity, and Nutrient Concentrations in Coastal Waters, December 2003-April 2006

    Science.gov (United States)

    Knee, Karen; Street, Joseph; Grossman, Eric E.; Paytan, Adina

    2008-01-01

    The aquatic resources of Kaloko-Honokohau National Historical Park, including rocky shoreline, fishponds, and anchialine pools, provide habitat to numerous plant and animal species and offer recreational opportunities to local residents and tourists. A considerable amount of submarine groundwater discharge was known to occur in the park, and this discharge was suspected to influence the park's water quality. Thus, the goal of this study was to characterize spatial and temporal variations in the quality and quantity of groundwater discharge in the park. Samples were collected in December 2003, November 2005, and April 2006 from the coastal ocean, beach pits, three park observation wells, anchialine pools, fishponds, and Honokohau Harbor. The activities of two Ra isotopes commonly used as natural ground-water tracers (223Ra and 224Ra), salinity, and nutrient concentrations were measured. Fresh ground water composed a significant proportion (8-47 volume percent) of coastal-ocean water. This percentage varied widely between study sites, indicating significant spatial variation in submarine groundwater discharge at small (meter to kilometer) scales. Nitrate + nitrite, phosphate, and silica concentrations were significantly higher in nearshore coastal-ocean samples relative to samples collected 1 km or more offshore, and linear regression showed that most of this difference was due to fresh ground-water discharge. High-Ra-isotope-activity, higher-salinity springs were a secondary source of nutrients, particularly phosphate, at Honokohau Harbor and Aiopio Fishtrap. Salinity, Ra-isotope activity, and nutrient concentrations appeared to vary in response to the daily tidal cycle, although little seasonal variation was observed, indicating that submarine ground-water discharge may buffer the park's water quality against the severe seasonal changes that would occur in a system where freshwater inputs were dominated by rivers and runoff. Ra-isotope-activity ratios indicated

  8. Volcano hazards at Fuego and Acatenango, Guatemala

    Science.gov (United States)

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

    2001-01-01

    The Fuego-Acatenango massif comprises a string of five or more volcanic vents along a north-south trend that is perpendicular to that of the Central American arc in Guatemala. From north to south known centers of volcanism are Ancient Acatenango, Yepocapa, Pico Mayor de Acatenango, Meseta, and Fuego. Volcanism along the trend stretches back more than 200,000 years. Although many of the centers have been active contemporaneously, there is a general sequence of younger volcanism, from north to south along the trend. This massive volcano complex towers more than 3500 meters (m) above the Pacific coastal plain to the south and 2000 m above the Guatemalan Highlands to the north. The volcano complex comprises remnants of multiple eruptive centers, which periodically have collapsed to form huge debris avalanches. The largest of these avalanches extended more than 50 kilometers (km) from its source and covered more than 300 square km. The volcano has potential to produce huge debris avalanches that could inundate large areas of the Pacific coastal plain. In areas around the volcanoes and downslope toward the coastal plain, more than 100,000 people are potentially at risk from these and other flowage phenomena.

  9. System for ranking relative threats of U.S. volcanoes

    Science.gov (United States)

    Ewert, J.W.

    2007-01-01

    A methodology to systematically rank volcanic threat was developed as the basis for prioritizing volcanoes for long-term hazards evaluations, monitoring, and mitigation activities. A ranking of 169 volcanoes in the United States and the Commonwealth of the Northern Mariana Islands (U.S. volcanoes) is presented based on scores assigned for various hazard and exposure factors. Fifteen factors define the hazard: Volcano type, maximum known eruptive explosivity, magnitude of recent explosivity within the past 500 and 5,000 years, average eruption-recurrence interval, presence or potential for a suite of hazardous phenomena (pyroclastic flows, lahars, lava flows, tsunami, flank collapse, hydrothermal explosion, primary lahar), and deformation, seismic, or degassing unrest. Nine factors define exposure: a measure of ground-based human population in hazard zones, past fatalities and evacuations, a measure of airport exposure, a measure of human population on aircraft, the presence of power, transportation, and developed infrastructure, and whether or not the volcano forms a significant part of a populated island. The hazard score and exposure score for each volcano are multiplied to give its overall threat score. Once scored, the ordered list of volcanoes is divided into five overall threat categories from very high to very low. ?? 2007 ASCE.

  10. Persistent inflation at Aira caldera accompanying explosive activity at Sakurajima volcano: Constraining deformation source parameters from Finite Element inversions

    Science.gov (United States)

    Hickey, James; Gottsmann, Jo; Iguchi, Masato; Nakamichi, Haruhisa

    2015-04-01

    Aira caldera is located within Kagoshima Bay at the southern end of Kyushu, Japan. Sakurajima is an active post-caldera andesitic stratovolcano that sits on the caldera's southern rim. Despite frequent Vulcanian-type explosive activity, the area is experiencing continued uplift at a maximum rate of approximately 1.5 cm/yr with a footprint of 40 km, indicating that magma is being supplied faster than it is erupted. This is of particular concern as the amplitude of deformation is approaching the level inferred prior to the 1914 VEI 4 eruption. Using GPS data from 1996 - 2007 we explore causes for the uplift. To solve for the optimum deformation source parameters we use an inverse Finite Element method accounting for three-dimensional material heterogeneity (inferred from seismic tomography) and the surrounding topography of the region. The same inversions are also carried out using Finite Element models that incorporate simplified homogeneous or one-dimensional subsurface material properties, with and without topography. Results from the comparison of the six different models show statistically significant differences in the inferred deformation sources. This indicates that both subsurface heterogeneity and surface topography are essential in geodetic modelling to extract the most realistic deformation source parameters. The current best-fit source sits within a seismic low-velocity zone in the north-east of the caldera at a depth of approximately 14 km with a volume increase of 1.2 x 108 m3. The source location underlies a region of active underwater fumaroles within the Wakamiko crater and differs significantly from previous analytical modelling results. Seismic data further highlights areas of high seismic attenuation as well as large aseismic zones, both of which could allude to inelastic behaviour and a significant heat source at depth. To integrate these observations, subsequent forward Finite Element models will quantify the importance of rheology and

  11. Chasing lava: a geologist's adventures at the Hawaiian Volcano Observatory

    Science.gov (United States)

    Duffield, Wendell A.

    2003-01-01

    A lively account of the three years (1969-1972) spent by geologist Wendell Duffield working at the Hawaiian Volcano Observatory at Kilauea, one of the world's more active volcanoes. Abundantly illustrated in b&w and color, with line drawings and maps, as well. Volcanologists and general readers alike will enjoy author Wendell Duffield's report from Kilauea--home of Pele, the goddess of fire and volcanoes. Duffield's narrative encompasses everything from the scientific (his discovery that the movements of cooled lava on a lava lake mimic the movements of the earth's crust, providing an accessible model for understanding plate tectonics) to the humorous (his dog's discovery of a snake on the supposedly snake-free island) to the life-threatening (a colleague's plunge into molten lava). This charming account of living and working at Kilauea, one of the world's most active volcanoes, is sure to be a delight.

  12. One hundred years of volcano monitoring in Hawaii

    Science.gov (United States)

    Kauahikaua, Jim; Poland, Mike

    2012-01-01

    In 2012 the Hawaiian Volcano Observatory (HVO), the oldest of five volcano observatories in the United States, is commemorating the 100th anniversary of its founding. HVO's location, on the rim of Kilauea volcano (Figure 1)—one of the most active volcanoes on Earth—has provided an unprecedented opportunity over the past century to study processes associated with active volcanism and develop methods for hazards assessment and mitigation. The scientifically and societally important results that have come from 100 years of HVO's existence are the realization of one man's vision of the best way to protect humanity from natural disasters. That vision was a response to an unusually destructive decade that began the twentieth century, a decade that saw almost 200,000 people killed by the effects of earthquakes and volcanic eruptions.

  13. Petrological insights into pre- and syn-eruptive degassing at Ambrym volcano, Vanuatu

    OpenAIRE

    Sheehan, Fionnuala

    2016-01-01

    Abstract This study is a petrological investigation of magmatic conditions and degassing processes at Ambrym volcano, a basaltic island arc volcano recently identified as a prodigious emitter of volcanic gases. Typical activity at this volcano entails heavy degassing from quasipermanent lava lakes, with Strombolian activity of fluctuating intensity. This is punctuated on an approximately decadal timescale by moderate sub-Plinian paroxysms, often accompanied by overflow of la...

  14. GLACIER-VOLCANO INTERACTIONS IN SOUTHERN CHILE: VOLCANIC HAZARD AND CLIMATE CHANGE IMPLICATIONS.

    OpenAIRE

    Sergio Andres Rivera Ibanez; Gino Casassa Rogazinski; Jorge Eduardo Clavero Ribes; Claudio Bravo Lechuga; Angelo Castruccio Alvarez; Pablo Zenteno Soto

    2004-01-01

    GLACIER-VOLCANO INTERACTIONS IN SOUTHERN CHILE: VOLCANIC HAZARD AND CLIMATE CHANGE IMPLICATIONS A 3 years long study on the glacier-volcano interaction in Southern Chile (Los Lagos Region), where most glaciers are located on active volcanic cones. The main objective of the project is differentiating glacier responses to climate changes from responses that might be caused by geothermal systems associated to active volcanoes. In the last few years, most glaciers in the region have significa...

  15. Turtles to Terabytes: The Ongoing Revolution in Volcano Geodesy

    Science.gov (United States)

    Dzurisin, D.

    2015-12-01

    Volcano geodesy is in the midst of a revolution. GPS and InSAR, together with extensive ground-based sensor networks, have enabled major advances in understanding how and why volcanoes deform. Surveying techniques that produced a few bytes of information per benchmark per year have been replaced by continuously operating deformation networks and imaging radar satellites that generate terabytes of data at resolutions unattainable only a few decades ago. These developments have enabled more detailed assessments of volcano hazards, more accurate forecasts of volcanic activity, and better insights into how volcanoes behave over a variety of spatial and temporal scales. Forty years ago, repeated leveling surveys showed that the floor of the Yellowstone caldera had risen more than 70 cm in the past 5 decades. Today a network of GPS stations tracks surface movements continuously with millimeter-scale accuracy and the entire deformation field is imaged frequently by a growing number of SAR satellites, revealing a far more complex style of deformation than was recognized previously. At Mount St. Helens, the 1980-1986 eruption taught us that a seemingly quiescent volcano can suddenly become overtly restless, and that accurate eruption predictions are possible at least in some limited circumstances given sufficient observations. The lessons were revisited during the volcano's 2004-2008 eruption, during which a new generation of geodetic sensors and methods detected a range of co-eruptive changes that enabled new insights into the volcano's magma storage and transport system. These examples highlight volcano deformation styles and scales that were unknown just a few decades ago but now have been revealed by a growing number of data types and modeling methods. The rapid evolution that volcano geodesy is currently experiencing provides an ongoing challenge for geodesists, while also demonstrating that geodetic unrest is common, widespread, and illuminating. Vive la révolution!

  16. MVAC Submarine cable, impedance measurements and analysis

    DEFF Research Database (Denmark)

    Arentsen, Martin Trolle; Pedersen, Morten Virklund; Expethit, Adrian

    2017-01-01

    Due to environmental concerns an increase in off-shore windfarms has been observed in recent years, leading to an increased demand for three-core-wire-armoured submarine cables. However, the IEC Standard 60287 used to calculate the ampacity of these cables is widely recognized as being not accurate...

  17. German Submarine Offensives and South African Countermeasures

    African Journals Online (AJOL)

    Evert

    'Good Hunting': German Submarine Offensives and South African. Countermeasures off the South African Coast during the Second World. War, 1942-1945. Evert Kleynhans. •. Abstract .... wolf packs south, Dönitz had hoped to cause a diversionary effect whereby the Allies would be forced to split their defensive forces ...

  18. Submarine Telecommunication Cables in Disputed Maritime Areas

    NARCIS (Netherlands)

    van Logchem, Youri

    2014-01-01

    There are a considerable number of maritime areas where no boundary exists, or where a boundary is delimited only in part. This article deals with the issue of submarine telecommunication cables, which are sometimes placed on the seabed or buried in the subsoil of areas that are claimed by multiple

  19. Seismicity at Baru Volcano, Western Panama, Panama

    Science.gov (United States)

    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

  20. Chemical environments of submarine hydrothermal systems

    Science.gov (United States)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such

  1. Phase 1 Final Report: Titan Submarine

    Science.gov (United States)

    Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

    2015-01-01

    The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of

  2. Health and environmental risk assessment associated with a potential recovery of the Russian submarine K-27

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, A.; Amundsen, I.; Brown, J.E.; Dowdall, M.; Standring, W. [Norwegian Radiation Protection Authority/CERAD CoE (Norway); Bartnicki, J. [Norwegian Meteorological Institute/CERAD CoE (Norway); Karcher, M. [O.A.Sys - Ocean Atmosphere Systems GmbH (Germany); Lind, O.C.; Salbu, B. [Norwegian University of Life Sciences/CERAD CoE (Norway)

    2014-07-01

    The nuclear submarine K-27 is one of several objects with spent nuclear fuel (SNF) which has been dumped in the Arctic. It contained two liquid metal reactors (LMRs) of 70 MW maximum thermal power each and used Pb-Bi as the coolant. The reactors were loaded with 180 kg of U-235 at an enrichment of 90 %. In September 1981, the submarine was sunk in the shallow waters of Stepovoy Fjord at an estimated depth of 30 m. Concerns have been expressed by various parties regarding the issue of dumped nuclear waste in the Kara Sea and in particular the submarine K-27. To address these concerns and to provide a better basis for evaluating possible radiological impact (especially as a consequence of a potential recovery of the submarine), an environmental impact assessment has been undertaken. The study is based on construction of different hypothetical accident scenarios and evaluating possible associated consequences for human and the environment. In general, three main scenarios seem probable and thus appropriate for consideration. One is the 'zero- alternative', i.e. investigate the current and future impact assuming no interventions. The second considers an accidental scenario involving the raising of the submarine and the third an accidental scenario related to the transportation of the submarine to shore for defueling. With regards to the accidental scenarios related to raising and transportation of the submarine, two alternatives can be considered depending on where and how a hypothetical accident will take place and whether the subsequent releases occur under water or at the water surface. The issue of an uncontrolled chain reaction occurring as a result of a potential recovery of the submarine will be included in the assessment. The work includes application of state of the art 3D hydrodynamic and atmospheric dispersion models to investigate the transport, distribution and fate of relevant radionuclides following a hypothetical accident in aquatic and

  3. Response of the Black Sea methane budget to massive short-term submarine inputs of methane

    DEFF Research Database (Denmark)

    Schmale, O.; Haeckel, M.; McGinnis, D. F.

    2011-01-01

    A steady state box model was developed to estimate the methane input into the Black Sea water column at various water depths. Our model results reveal a total input of methane of 4.7 Tg yr(-1). The model predicts that the input of methane is largest at water depths between 600 and 700 m (7......% of the total input), suggesting that the dissociation of methane gas hydrates at water depths equivalent to their upper stability limit may represent an important source of methane into the water column. In addition we discuss the effects of massive short-term methane inputs (e. g. through eruptions of deep......-water mud volcanoes or submarine landslides at intermediate water depths) on the water column methane distribution and the resulting methane emission to the atmosphere. Our non-steady state simulations predict that these inputs will be effectively buffered by intense microbial methane consumption...

  4. ICE-VOLC Project: unravelling the dynamics of Antarctica volcanoes

    Science.gov (United States)

    Cannata, Andrea; Del Carlo, Paola; Giudice, Gaetano; Giuffrida, Giovanni; Larocca, Graziano; Liuzzo, Marco

    2017-04-01

    Melbourne and Rittmann volcanoes are located in the Victoria Land. Whilst Rittmann's last eruption dates probably to Pleistocene, Melbourne's most recent eruption between 1862 and 1922, testifying it is still active. At present, both volcanoes display fumarolic activity. Melbourne was discovered in 1841 by James Clark Ross, Rittmann during the 4th Italian Expedition (1988/1989). Our knowledge on both volcanoes is really little. The position of these volcanoes in the Antarctic region (characterised by absence of anthropic noise) and its proximity with the Italian Mario Zucchelli Station makes them ideal sites for studying volcano seismic sources, geothermal emissions, seismo-acoustic signals caused by cryosphere-hydrosphere-atmosphere dynamics, and volcanic gas impact on environment. Hence, the main aim of the ICE-VOLC ("multiparametrIC Experiment at antarctica VOLCanoes: data from volcano and cryosphere-ocean-atmosphere dynamics") project is the study of Melbourne and Rittmann, by acquisition, analysis and integration of multiparametric geophysical, geochemical and thermal data. Complementary objectives include investigation of the relationship between seismo-acoustic activity recorded in Antarctica and cryosphere-hydrosphere-atmosphere dynamics, evaluation of the impact of volcanic gas in atmosphere. This project involves 26 researchers, technologists and technicians from University of Perugia and from Istituto Nazionale di Geofisica e Vulcanologia of Catania, Palermo, Pisa and Rome. In this work, we show the preliminary results obtained after the first expedition in Antarctica, aiming to perform geochemical-thermal surveys in the volcano ice caves, as well as to collect ash samples and to install temporary seismic stations.

  5. Efficient inversion of volcano deformation based on finite element models : An application to Kilauea volcano, Hawaii

    Science.gov (United States)

    Charco, María; González, Pablo J.; Galán del Sastre, Pedro

    2017-04-01

    The Kilauea volcano (Hawaii, USA) is one of the most active volcanoes world-wide and therefore one of the better monitored volcanoes around the world. Its complex system provides a unique opportunity to investigate the dynamics of magma transport and supply. Geodetic techniques, as Interferometric Synthetic Aperture Radar (InSAR) are being extensively used to monitor ground deformation at volcanic areas. The quantitative interpretation of such surface ground deformation measurements using geodetic data requires both, physical modelling to simulate the observed signals and inversion approaches to estimate the magmatic source parameters. Here, we use synthetic aperture radar data from Sentinel-1 radar interferometry satellite mission to image volcano deformation sources during the inflation along Kilauea's Southwest Rift Zone in April-May 2015. We propose a Finite Element Model (FEM) for the calculation of Green functions in a mechanically heterogeneous domain. The key aspect of the methodology lies in applying the reciprocity relationship of the Green functions between the station and the source for efficient numerical inversions. The search for the best-fitting magmatic (point) source(s) is generally conducted for an array of 3-D locations extending below a predefined volume region. However, our approach allows to reduce the total number of Green functions to the number of the observation points by using the, above mentioned, reciprocity relationship. This new methodology is able to accurately represent magmatic processes using physical models capable of simulating volcano deformation in non-uniform material properties distribution domains, which eventually will lead to better description of the status of the volcano.

  6. Submarine glaciated landscapes of central and northern British Columbia, Canada

    Science.gov (United States)

    Shaw, John; Lintern, Gwyn

    2015-04-01

    Recent systematic multibeam sonar mapping and ground-truthing surveys in the fjords and coastal waters of central and northern British Columbia, Canada, provide information on glacial processes associated with the Cordilleran Ice Sheet, and also on postglacial processes that have strongly modified the glacial terrain. During the last glacial maximum, ice covered the Coast Range, except for nunataks. Convergent streamlined glacial landforms in the Strait of Georgia testify to a strong flow of ice towards the southeast, between Vancouver Island and the mainland. During ice retreat, thick deposits of acoustically stratified glaciomarine mud were deposited in glacially over deepened basins. Retreat through the Douglas Channel fjord system was punctuated by still stands, resulting in a series of submarine moraines. Postglacial processes have created a suite of landforms that mask the primary glacial terrain: 1) Fjord floors host thick deposits of acoustically transparent postglacial mud with highly variable distribution: banks up to 80-m thick are commonly adjacent to erosional zones with glaciomarine mud exposed at the seafloor; 2) In this region of high precipitation and snowpack melt, numerous cone-shaped Holocene fan deltas developed on the fjord sidewalls transport coarse sediment to the fjord floors. Larger deltas are developed at fjord heads, notably at Kitimat and Kildala; 3) Submarine slope failures in this tectonically active area have resulted in a suite of mass transport deposits on sidewalls and fjord floors. The very large submarine slope failures at Camano Sound and KitKat Inlet occurred on the steep, rear facets of large transverse moraines, and involved the failure of glaciomarine sediment that moved into deeper basins, perhaps as a retrogressive failure. The ages of these events are unknown, although the presence of postglacial mud in the slide scar at Caamano suggests that the event at that location occurred in the late glacial or early Holocene. Also

  7. Evidence for explosive volcanic density currents on certain Martian volcanoes

    Science.gov (United States)

    Reimers, C. E.; Komar, P. D.

    1979-01-01

    The morphologies of certain of the smaller Martian volcanoes are discussed as possible results of explosive volcanic density currents. An examination of newly-photographed flank and caldera features of the Martian volcanoes Ceraunius Tholus, Uranius Tholus, Uranius Patera and Hecates Tholus, including steep slope angles, Krakatoa-type caldera morphologies, erosional features (radial channels and anastamosing gullies) and constructional features (blanketed flanks and possible lava deltas) reveals their similarity to terrestrial cones and composite volcanoes such as Barcena Volcano. Crater age data from the surface of Martian domes and shields indicates that such explosive activity occurred more frequently early in Martian geologic history, consistent with the view that the volcanic density currents were base surges rather than nuees ardentes, with the melting of permafrost supplying the water required in base surge generation.

  8. Examining the interior of Llaima Volcano with receiver functions

    Science.gov (United States)

    Bishop, J. W.; Lees, J. M.; Biryol, C. B.; Mikesell, T. D.; Franco, L.

    2018-02-01

    Llaima Volcano in Chile is one of the largest and most active volcanoes in the southern Andes, with over 50 eruptions since the 1600s. After years of persistent degassing, Llaima most recently erupted in a series of violent Strombolian eruptions in 2007-2009. This period had few precursory signals, which highlights the need to obtain accurate magma storage information. While petrologic advancements have been made in understanding magma degassing and crystallization trends, a comprehensive seismic study has yet to be completed. Here we present results of a receiver function survey utilizing a dense seismic array surrounding Llaima Volcano. Application of H-κ stacking and Common Conversion Point stacking techniques reveal the general structural architecture and ceiling of a low velocity zone between 8 and 13 km beneath Llaima Volcano. We interpret this anomaly as a deep magma accumulation zone.

  9. Numerical Simulation for Scenario Based Volcanic Hazard Assessment (VHA) at Seulawah Agam Volcano, Aceh, Sumatra

    OpenAIRE

    Syukri, Muhammad; Fauzi, Amir; Fashbir,; Irwandi,

    2012-01-01

    Seulawah Agam is an active volcano with high 1,810 m located at 5.448°N 95.658°E and close to the capital of Aceh province densely populated. Following Sumatra-Andaman earthquake 26 December 2004, Sumatra Island has increased not only seismicity but also volcanic activity. On the other hand, Sinabung volcano categorized as inactive volcano, but beyond expectations on the 3rd September 2010 experienced eruption and the closest volcanic eruption location to Seulawah Agam volcano. Meanwhile, in ...

  10. Repeating LP events and increases in high-frequency seismic energy preceding the December 1999 eruption of the quiescently active Telica Volcano, Nicaragua

    Science.gov (United States)

    Rodgers, M.; Roman, D. C.; Geirsson, H.; Lafemina, P.; Muñoz, A.; Guzman, C.; Tenorio, V.

    2010-12-01

    Telica volcano, Nicaragua, is a ‘quiescently active’ basaltic andesite stratovolcano located in the Central American volcanic front. A high rate of long-period (LP) seismicity has been recorded at Telica since the installation of a single vertical-component 1 Hz seismic sensor (TELN) near its summit in 1993 by the Instituto Nicaragüense de Estudios Territoriales (INETER). Due to the continuously high rate of LPs at Telica, traditional methods of forecasting volcanic activity may not be applicable; therefore an understanding of the nature of precursory changes in Telica’s seismicity is necessary to accurately forecast future volcanic activity. A VEI 2 eruption of Telica occurred on the 29th December 1999, preceded by a series of small explosions between the 3rd-15th October 1999. Here we analyse an eight-month period of seismicity bracketing this activity, in an attempt to identify precursory changes with respect to background seismicity. Between August 1999 and March 2000 over 18,000 seismic events were recorded on TELN. We first calculated the dominant frequencies (i.e. frequency with dominant spectral energy) for all events recorded during this period. A time series of the dominant event frequencies between August 1999 and March 2000 shows a significant increase in the number of high frequency (> 5 Hz) events and, in LP events, a shift in the two dominant spectral energy peaks from 2 Hz and 4 Hz to 2 Hz and 3 Hz in the month before the October 1999 explosions. Next, we selected six representative eight-day periods, three from before the explosions and three from after, for multiplet analysis using waveform cross-correlation. Multiplet analysis of the six selected time periods reveal significant changes in behaviour. In period 1 (more than one month before the explosions) events are poorly correlated. In periods 2 and 3 (less than one month before the explosions) we identified several unique families of LP events, each having high cross-correlation values

  11. Long-term flow monitoring of submarine gas emanations

    Science.gov (United States)

    Spickenbom, K.; Faber, E.; Poggenburg, J.; Seeger, C.

    2009-04-01

    One of the Carbon Capture and Storage (CCS) strategies currently under study is the sequestration of CO2 in sub-seabed geological formations. Even after a thorough review of the geological setting, there is the possibility of leaks from the reservoirs. As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop innovative research and technologies for monitoring and verification of carbon dioxide geological storage, we are working on the development of submarine long-term gas flow monitoring systems. Technically, however, these systems are not limited to CO2 but can be used for monitoring of any free gas emission (bubbles) on the seafloor. The basic design of the gas flow sensor system was derived from former prototypes developed for monitoring CO2 and CH4 on mud volcanoes in Azerbaijan. This design was composed of a raft floating on the surface above the gas vent to collect the bubbles. Sensors for CO2 flux and concentration and electronics for data storage and transmission were mounted on the raft, together with battery-buffered solar panels for power supply. The system was modified for installation in open sea by using a buoy instead of a raft and a funnel on the seafloor to collect the gas, which is then guided above water level through a flexible tube. Besides some technical problems (condensed water in the tube, movement of the buoys due to waves leading to biased measurement of flow rates), this setup provides a cost-effective solution for shallow waters. However, a buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. These requirements can best be complied by a completely submersed system. To allow unattended long-term monitoring in a submarine environment, such a system has to be extremely durable. Therefore, we focussed on developing a mechanically and electrically as simple setup as possible, which has the additional advantage of low cost. The system

  12. Origin of the Easter Submarine Alignment: morphology and structural lineaments

    Directory of Open Access Journals (Sweden)

    Cristián Rodrigo

    2014-10-01

    Full Text Available The Easter submarine alignment corresponds to a sequence of seamounts and oceanic islands which runs from the Ahu-Umu volcanic fields in the west to its intersection with the Nazca Ridge in the east, with a total length of about 2.900 km and a strike of N85°E. Recent bathymetric compilations that include combined satellite derived and shipboard data (Global Topography and multibeam bathymetric data (from NGDC-NOAA are interpreted both qualitatively and quantitatively by using a morphological analysis, which was comprised of the determination of bathymetric patterns, trends in lineations and structures; height measurements, computation of basal areas and volumes of seamounts, in order to establish clues on the origin of this seamount chain and to establish relationships with the regional tectonics. In the study region 514 seamounts were counted, of which 334 had a basal area less than the reference seamount (Moai. In general, the largest seamounts (>1000 m in height tend to align and to have a larger volume, with an elongation of their bases along the seamount chain. On the other hand, smaller seamounts tend to be distributed more randomly with more circular bases. As a consequence of the morphological analysis, the best possible mechanism that explains the origin of the seamount chain is the existence of a localized hotspot to the west of the Salas y Gómez Island. The corresponding plume would contribute additional magmatic material towards the East Pacific Rise through canalizations, whose secondary branches would feed intermediate volcanoes. It is possible that within the Easter Island region there would be another minor contribution through fractures in the crust, due to the crustal weakening that was produced by the Easter Fracture Zone.

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

    Science.gov (United States)

    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.

  14. Submarine geology of South Kona landslide complex: investigation using ROV Kaiko

    Science.gov (United States)

    Yokose, H.; Yoshida, S.

    2002-12-01

    KR01-12 cruise of Japan Marine Science and Technology Center using ROV KAIKO and its mother ship R/V KAIREI were carried out around Hawaii islands in the early fall of 2001. During this cruise, two dives of ROV KAIKO were made on western submarine flank of the island of Hawaii: South Kona landslide complex (K210:proximal part of the south Kona landslide, K211: distal block of the landslide). One single channel seismic reflection line was collected from vicinity of the above dive sites. These areas have never been systematically studied using submersible due to the bad sea state and /or the depth of outcrops. Valuable information about the submarine geology and in situ rock samples from western franks of the island of Hawaii were obtained. K211 site is one of the distal landslide block and can be divided into 3 geological units from bottom to top: picritic sheet lava and hyaloclastite, volcaniclastic deposit with picritic breccia, muddy breccia with highly vesiculated ol basalt. On the other hand, rocks recovered from K210 are composed mainly of aa clinker and aa lava which are highly vesiculated and reddish in color. The rocks from K210 is similar to the upper part of K211 in their bulk rock chemistry. Based on the geological and bulk rock chemistry, rocks recovered from both sites should be erupted subaerially. It suggests that these landslide blocks were composed subaerial portion of the paleo-Mauna Loa volcano.

  15. Impact of Submarine Geohazards on Organic Carbon Burial Offshore Southwestern Taiwan

    Science.gov (United States)

    Su, C. C.; Tsai, P. H.; Liu, J. T.; Hsu, S. K.; Chiu, S. D.

    2015-12-01

    The tectonically active setting and climatic conditions give Taiwan a high exposure to severe natural hazards. After the Pingtung Earthquake and Morakot Typhoon which occurred in 2006 and 2009, the turbidity currents caused a series of submarine cable breaks along the Gaoping and Fangliao Submarine Canyons off SW Taiwan. Large amounts of terrestrial sediments were fast transported bypass the narrow continental shelf and rapidly moved southward through submarine canyons to the deep sea. Two piston cores which were taken from the Tsangyao Ridge and its adjacent area (OR5-1302-2-MT7 and MT6) might shed light on understanding the export of terrestrial organic carbon to the abyss by submarine geo-hazards. The 210Pb profile of MT7 in conjunction with the grain size data indicates the existence of the Pingtung Earthquake and Morakot Typhoon related deposits. The sedimentation rate of these two cores which derived from 210Pb is approximately 0.05 cm/yr. The cores collected from the Gaoping Submarine Canyon, Gaoping Slope and Fangliao Submarine Canyon are used for analyzing TOC, organic C/N and δ13C ratios. The concentrations of total organic carbon are ~0.5%, and C/N rations almost remain between 4 and 8. The high TOC (~1%) and C/N ratio (>10) are observed in the samples with plant debris. The fluctuation of TOC and C/N ratios in near-shore samples is higher than deep sea. In terms of δ13C-values, it progressively decreases with distances from coastal zone to the deep sea. Due to the larger proportions of land-derived organic carbon, the δ13C-values in the surface sediment of upper Gaoping Submarine Canyon, Gaoping Slope, and the turbidite layers at the head of Fangliao Submarine Canyon are lighter. Furthermore, we use the TOC concentrations and δ13C-values to estimate the fractional contributions of terrestrial organic carbon by a simple two component mixing model, and integrate with the 210Pb-derived sediment accumulation rates to evaluate the organic carbon burial

  16. Shallow Resistivity Structure of Sakurajima Volcano Revealed by Audio-frequency Magnetotellurics

    OpenAIRE

    Kanda, Wataru; Yamazaki, Tomoya; Ogawa, Yasuo; Hashimoto, Takeshi; SAKANAKA, Shinʼya; aizawa, koki; Takakura, Shinichi; Koyama, Takao; Yamada, Kenta; Kobayashi, Tsukasa; KOMORI, Shogo

    2013-01-01

    An audio-frequency magnetotelluric (AMT) survey was conducted at the foot of Sakurajima volcano in November 2007. This survey was carried out within the framework of the 7th National Project for Prediction of Volcano Eruptions. The main objective was to clarify the shallow layers of Sakurajima volcano for better understanding of the volcanic activity. We measured electromagnetic fields at frequencies from 1 to 10400 Hz at 27 locations along only three lines set on the northern, we...

  17. Instability of Hawaiian volcanoes: Chapter 4 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Denlinger, Roger P.; Morgan, Julia K.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Hawaiian volcanoes build long rift zones and some of the largest volcanic edifices on Earth. For the active volcanoes on the Island of Hawai‘i, the growth of these rift zones is upward and seaward and occurs through a repetitive process of decades-long buildup of a magma-system head along the rift zones, followed by rapid large-scale displacement of the seaward flank in seconds to minutes. This large-scale flank movement, which may be rapid enough to generate a large earthquake and tsunami, always causes subsidence along the coast, opening of the rift zone, and collapse of the magma-system head. If magma continues to flow into the conduit and out into the rift system, then the cycle of growth and collapse begins again. This pattern characterizes currently active Kīlauea Volcano, where periods of upward and seaward growth along rift zones were punctuated by large (>10 m) and rapid flank displacements in 1823, 1868, 1924, and 1975. At the much larger Mauna Loa volcano, rapid flank movements have occurred only twice in the past 200 years, in 1868 and 1951.

  18. Shallow crustal velocities and volcanism suggested from ambient noise studies using a dense broadband seismic network in the Tatun Volcano Group of Taiwan

    Science.gov (United States)

    Huang, Yu-Chih; Lin, Cheng-Horng; Kagiyama, Tsuneomi

    2017-07-01

    The Tatun Volcano Group (TVG) is situated adjacent to the Taipei metropolis and was active predominantly around 0.8-0.2 Ma (Pleistocene). Various recent lines of evidence suggest that the TVG is a potentially active volcano and that future volcanic eruptions cannot be ruled out. Geothermal activities are largely constrained to faults, but the relationship between volcanism and detailed velocity structures is not well understood. We analyzed ambient seismic noise of daily vertical components from 2014 using a dense seismic network of 40 broadband stations. We selected a 0.02° grid spacing to construct 2D and 3D shallow crustal phase velocity maps in the 0.5-3 s period band. Two S-wave velocity profiles transect Chishingshan (Mt. CS) in the shallow 3 km crust are further derived. The footwall of the Shanchiao Fault is dominated by low velocity, which may relate to Tertiary bedrock buried under andesitic lava flows dozens to hundreds of meters thick. The hanging wall of the Shanchiao Fault is the location of recent major volcanic activities. Low velocity zones in the southeast of Dayoukeng (DYK) may be interpreted as hydrothermal reservoirs or water-saturated Tertiary bedrock related to Cenozoic structures in the shallow crust. High velocities conspicuously dominate the east of the TVG, where the earliest stages of volcanism in the TVG are located, but where surface hydro-geothermal activities were absent in recent times. Between the Shanchiao Fault and Kanchiao Fault high velocities were detected, which converge below Mt. CS and may be related to early stages of magma conduits that gradually consolidated. These two faults may play a significant role with the TVG. The submarine volcanism adjacent to the Keelung coastline also requires further attention.

  19. Preliminary Result of The Influence of Earthquake Stress Change and The Implication for Soputan Volcano and Lokon Volcano

    Science.gov (United States)

    Bunaga, I. G. K. S.; Nugraha, M. F.

    2017-04-01

    On February 6, 2016, an eruption occurred on the Northern Sulawesi arm, particularly Soputan volcano. One day earlier, Lokon volcano located close to Soputan volcano was decreased its status from standby to alert level by the Center for Volcanology and Geological Hazard Mitigation (CVGHM). The different reactions of two volcanoes proposed the question why the increment activity just happened in Soputan volcano. This uniqueness made us to suggest that static stress of earthquake may control the magmatic systems. We investigate here the earthquake-volcanism interaction through static stress changes by using Coulomb failure stress associated with an earthquake occurred in the Northern Molluca Sea on 25 November 2015. We slice the same dip for the each region in vertical cross sections. Therefore, the Coulomb failure stress pattern can be investigated beneath the study area. Our results suggest that Coulomb failure stress was increased by 0.3 × 10-3 to 0.4 × 10-3 bar below the Soputan’s region. Lokon’s region, the stress was reduced by -0.1 × 10-3 to -0.4 × 10-3 bar. The positive change may perturb magma overpressure leading to eruption and promoted volcanic earthquakes. The situation was very different that Lokon volcano ran into reduction activity and volcanic earthquakes were discourage due to stress shadow. We show that the difference volcanic response were likely controlled by static stress of the earthquake.

  20. Seismicity and sedimentation rate effects on submarine slope stability

    Science.gov (United States)

    Ten Brink, U. S.; Andrews, B. D.; Miller, N. C.

    2016-12-01

    Large submarine mass-transport scars are commonly observed on continental margins, but are noticeably less abundant on margins that experience frequent earthquakes than on those that seldom experience them. This is a surprising observation, given that horizontal acceleration from earthquakes and associated strength loss from cyclic loading and liquefaction are commonly thought to provide the primary triggers for inducing failures and subsequent mass movements. Mapping submarine failure scars in ten margins worldwide, we find decreasing scar abundance with both increasing frequency of earthquakes and decreasing sedimentation rate. The decrease in scar abundance is interpreted to represent increasing slope stability. The increase in stability is non linear (power law with btectonic activity (salt diapirs, seamount subduction, etc.) leads to relatively rapid oversteepening of the slope, implying that the morphology of most margins is in fact, stable over many earthquake cycles. Note that the above correlation averages scar area and sedimentation rate over entire margin areas. Variations in sedimentation rate with time, such as over glacial-interglacial cycles, and intra-margin variations in seismic attenuation, sedimentation rate, composition, and pore pressure, have likely affected the abundance of slope failures in time and space.

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

    Science.gov (United States)

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

    2016-04-01

    There are 36 active volcanoes in the Kamchatka and North Kurile, and several of them are continuously active. In 2015, four of the Kamchatkan volcanoes (Sheveluch, Klyuchevskoy, Karymsky and Zhupanovsky) and two volcanoes of North Kurile (Alaid and Chikurachki) had strong and moderate explosive eruptions. Moderate gas-steam activity was observing of Bezymianny, Kizimen, Avachinsky, Koryaksky, Gorely, Mutnovsky and other volcanoes. Strong explosive eruptions of volcanoes are the most dangerous for aircraft because they can produce in a few hours or days to the atmosphere and the stratosphere till several cubic kilometers of volcanic ash and aerosols. Ash plumes and the clouds, depending on the power of the eruption, the strength and wind speed, can travel thousands of kilometers from the volcano for several days, remaining hazardous to aircraft, as the melting temperature of small particles of ash below the operating temperature of jet engines. The eruptive activity of Sheveluch volcano began since 1980 (growth of the lava dome) and is continuing at present. Strong explosive events of the volcano occurred in 2015: on 07, 12, and 15 January, 01, 17, and 28 February, 04, 08, 16, 21-22, and 26 March, 07 and 12 April: ash plumes rose up to 7-12 km a.s.l. and extended more 900 km to the different directions of the volcano. Ashfalls occurred at Ust'-Kamchatsk on 16 March, and Klyuchi on 30 October. Strong and moderate hot avalanches from the lava dome were observing more often in the second half of the year. Aviation color code of Sheveluch was Orange during the year. Activity of the volcano was dangerous to international and local aviation. Explosive-effusive eruption of Klyuchevskoy volcano lasted from 01 January till 24 March. Strombolian explosive volcanic activity began from 01 January, and on 08-09 January a lava flow was detected at the Apakhonchich chute on the southeastern flank of the volcano. Vulcanian activity of the volcano began from 10 January. Ashfalls

  2. KrakMon: Seismic signals recorded at Krakatau Volcano, Indonesia

    Science.gov (United States)

    Ibs-von Seht, M.; Hoffmann-Rothe, A.; Kniess, R.

    2005-12-01

    A recently installed multi-parameter monitoring system on the Krakatau volcanic island complex located in the Sunda Strait (Indonesia) provides continuous broadband records of seismic data. We present here an overview of the different signal types identified and first results of an automated detection and classification procedure for volcano-seismic events recorded at Krakatau volcano. In comparison to seismic signals known from other volcanoes, an unusually high portion of high-frequency content is observed in the spectra of the Krakatau signals. This observation applies to short-term volcano-tectonic (VT) events as well as to continuous tremor signals: most VT events show significant energy at frequencies above 30Hz, harmonic signals last almost continuously for days and show spectral peaks at distinct frequencies well above15Hz. The automated detection and classification procedure bases a spectrogram analysis of volcano-seismic signals using a straight-forward pattern recognition approach: a suitable threshold operator generates a binary representation of the spectrogram which is processed by a contour finding algorithm. The resulting contour-polygons define regions in the spectrogram containing significant spectral energy and their shapes reveal information about the respective volcano-seismic signals. By the extraction of stable shape-describing properties from the polygons and their statistical analysis it is attempted to identify different classes of signal types. A comparison of the resulting signal types with those determined visually by the operator can improve classification schemes for volcano-seismic signals and contribute to defining the activity status of Krakatau and other volcanoes.

  3. Three-dimensional shallow velocity structure beneath Taal Volcano, Philippines

    Science.gov (United States)

    You, Shuei-Huei; Konstantinou, Konstantinos I.; Gung, Yuancheng; Lin, Cheng-Horng

    2017-11-01

    Based on its numerous historical explosive eruptions and high potential hazards to nearby population of millions, Taal Volcano is one of the most dangerous "Decade Volcanoes" in the world. To provide better investigation on local seismicity and seismic structure beneath Taal Volcano, we deployed a temporary seismic network consisting of eight stations from March 2008 to March 2010. In the preliminary data processing stage, three periods showing linear time-drifting of internal clock were clearly identified from noise-derived empirical Green's functions. The time-drifting errors were corrected prior to further data analyses. By using VELEST, 2274 local earthquakes were manually picked and located. Two major earthquake groups are noticed, with one lying beneath the western shore of Taal Lake showing a linear feature, and the other spreading around the eastern flank of Taal Volcano Island at shallower depths. We performed seismic tomography to image the 3D structure beneath Taal Volcano using the LOTOS algorithm. Some interesting features are revealed from the tomographic results, including a solidified magma conduit below the northwestern corner of Taal Volcano Island, indicated by high Vp, Vs, and low Vp/Vs ratio, and a large potential hydrothermal reservoir beneath the center of Taal Volcano Island, suggested by low Vs and high Vp/Vs ratio. Furthermore, combining earthquake distributions and tomographic images, we suggest potential existence of a hydrothermal reservoir beneath the southwestern corner of Taal Lake, and a fluid conduit extending to the northwest. These seismic features have never been proposed in previous studies, implying that new hydrothermal activity might be formed in places away from the historical craters on Taal Volcano Island.

  4. Continuous monitoring of volcanoes with borehole strainmeters

    Science.gov (United States)

    Linde, Alan T.; Sacks, Selwyn

    Monitoring of volcanoes using various physical techniques has the potential to provide important information about the shape, size and location of the underlying magma bodies. Volcanoes erupt when the pressure in a magma chamber some kilometers below the surface overcomes the strength of the intervening rock, resulting in detectable deformations of the surrounding crust. Seismic activity may accompany and precede eruptions and, from the patterns of earthquake locations, inferences may be made about the location of magma and its movement. Ground deformation near volcanoes provides more direct evidence on these, but continuous monitoring of such deformation is necessary for all the important aspects of an eruption to be recorded. Sacks-Evertson borehole strainmeters have recorded strain changes associated with eruptions of Hekla, Iceland and Izu-Oshima, Japan. Those data have made possible well-constrained models of the geometry of the magma reservoirs and of the changes in their geometry during the eruption. The Hekla eruption produced clear changes in strain at the nearest instrument (15 km from the volcano) starting about 30 minutes before the surface breakout. The borehole instrument on Oshima showed an unequivocal increase in the amplitude of the solid earth tides beginning some years before the eruption. Deformational changes, detected by a borehole strainmeter and a very long baseline tiltmeter, and corresponding to the remote triggered seismicity at Long Valley, California in the several days immediately following the Landers earthquake are indicative of pressure changes in the magma body under Long Valley, raising the question of whether such transients are of more general importance in the eruption process. We extrapolate the experience with borehole strainmeters to estimate what could be learned from an installation of a small network of such instruments on Mauna Loa. Since the process of conduit formation from the magma sources in Mauna Loa and other

  5. Psychological Implications for Submarine Display Design

    Science.gov (United States)

    2005-08-01

    This paper addresses a number of psychological issues pertaining to display design . We review the literature comparing 3-D and 2-D displays and...perceptual, cognitive and ecological factors that are relevant to display design for submarine environments. The Generative Transformational approach...to visual perception is outlined and the relevance of transformational theory to display design is discussed. The paper also discusses a number of

  6. Counterfactual Volcano Hazard Analysis

    Science.gov (United States)

    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.

  7. Topology Model of the Flow around a Submarine Hull Form

    Science.gov (United States)

    2015-12-01

    resistance and flow noise arising from flow-structure interaction, it is necessary to test the shape of the submarine , which includes the length-to...UNCLASSIFIED Topology Model of the Flow around a Submarine Hull Form S.-K. Lee Maritime Division Defence Science and Technology Group DST-Group–TR...3177 ABSTRACT A topology model constructed from surface-streamer visualisation describes the flow around a generic conventional submarine hull form at

  8. A Lanchester model of submarine attack on a carrier battlegroup

    OpenAIRE

    Eagle, James N.

    1987-01-01

    A Lanchester model is developed for a battlegroup ASW engagement. Two variations are included. In the first, long-range missile firing submarines, short-range missile or torpedo firing submarines, and submarines firing only torpedoes distribute their attack uniformly over battlegroup escort ships and carriers. In the second variation, the attack is concentrated on the carriers. supported by the Naval War College http://archive.org/details/lanchestermodelo00eagl NA

  9. Preliminary Volcano-Hazard Assessment for Gareloi Volcano, Gareloi Island, Alaska

    Science.gov (United States)

    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.

  10. Volcano monitoring with an infrared camera: first insights from Villarrica Volcano

    Science.gov (United States)

    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

  11. Microbial biodiversity of Tang and Pirgal mud volcanoes and evaluation of bio-emulsifier and bio-demulsifier activities of Capnophile bacteria.

    Science.gov (United States)

    Parsia, Yasaman; Sorooshian, Shahryar

    2017-12-01

    The data presented in this article is related to the Master thesis; entitled "Survey Aerobic Microbial Diversity Mud Volcanoes in Chabahar and Khash Ports in Southern Iran" by the first author of this article, year 2011, Islamic Azad University, Iran (reference number (Parsia, 2011) [1] of this article). This article shows microbial biodiversity and evaluates bio-emulsifier and bio-demulsifier abilities of capnophile isolates, in order to introduce a superior isolate for the Microbial Enhanced Oil Recovery (MEOR) process in the petrochemical industry.

  12. Response of the Black Sea methane budget to massive short-term submarine inputs of methane

    Directory of Open Access Journals (Sweden)

    O. Schmale

    2011-04-01

    Full Text Available A steady state box model was developed to estimate the methane input into the Black Sea water column at various water depths. Our model results reveal a total input of methane of 4.7 Tg yr−1. The model predicts that the input of methane is largest at water depths between 600 and 700 m (7% of the total input, suggesting that the dissociation of methane gas hydrates at water depths equivalent to their upper stability limit may represent an important source of methane into the water column. In addition we discuss the effects of massive short-term methane inputs (e.g. through eruptions of deep-water mud volcanoes or submarine landslides at intermediate water depths on the water column methane distribution and the resulting methane emission to the atmosphere. Our non-steady state simulations predict that these inputs will be effectively buffered by intense microbial methane consumption and that the upward flux of methane is strongly hampered by the pronounced density stratification of the Black Sea water column. For instance, an assumed input of methane of 179 Tg CH4 d−1 (equivalent to the amount of methane released by 1000 mud volcano eruptions at a water depth of 700 m will only marginally influence the sea/air methane flux increasing it by only 3%.

  13. Darwin's triggering mechanism of volcano eruptions

    Science.gov (United States)

    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

  14. Possible climate preconditioning on submarine landslides along a convergent margin, Nankai Trough (NE Pacific)

    Science.gov (United States)

    Kremer, Katrina; Usman, Muhammed O.; Satoguchi, Yasufumi; Nagahashi, Yoshitaka; Vadakkepuliyambatta, Sunil; Panieri, Giuliana; Strasser, Michael

    2017-12-01

    Submarine landslides are major agents of sediment mass transfer from the shallow to deep sea. Due to their rapid emplacement and tsunamigenic potential, such landslides are significant geohazards for society and off- and on-shore infrastructure. The relationship between climate change and the occurrence of submarine landslides is widely debated. However, there is a lack of continuous long-term submarine landslide records with which to comprehensively understand the relationship between climate-driven forces and submarine landslide occurrence. Here, using oxygen isotope stratigraphy in combination with tephrochronology, we date a 1 Myr continuous record of six landslide deposits (at 13.0-14.2, 323-339, 372-384, 394-413, 508-521, and 857-867 ka) recorded in a slope basin of the Nankai Trough subduction zone, off-shore Japan, which represents the major outcome of this study. The ages of the six landslides coincide mostly with interglacial periods. Thus, we propose that climate forcing might act as a preconditioning factor for slope instability in this active tectonic region.[Figure not available: see fulltext.

  15. Deformation time series at Llaima volcano, southern Andes

    Science.gov (United States)

    Bathke, Hannes; Walter, Thomas; Motagh, Mahdi; Shirzaei, Manoochehr

    2010-05-01

    Llaima volcano, with an edifice height of 3125 m and a volume of about 400 km³, is one of the largest and most active volcanoes in South America. Its eruptive history suggest a potential for very large and hazardous eruptions including pyroclastic flows, air falls and material remobilization in the form of lahars affecting regions even at the lower apron and beyond, posing a significant risk to civilizations, infrastructure and traffic ways. Llaima volcano is near constantly active; since the 17th century strombolian eruptions occurred at a mean frequency of one eruptive phase every five years. Although this strong activity and socioeconomic importance the source of magma, possible magma reservoirs and deformations prior to or associated with eruptions are hitherto unknown. One of the problems for establishing a monitoring system is that Llaima is difficult to access and located in vegetated and topographically rough terrain. To better understand the volcano physics, we created an InSAR time series based on the PS technique using 18 Envisat images from Dezember 2002 to November 2008. Using the StaMPS software we obtained 24,000 stable pixels in the vicinity of the volcano, that allow to investigate a spatiotemporal displacement field. Associated with the recent eruptions, we observed non-linear subsidence at the vicinity of the volcano base. We assessed the validiy of the deformation signal, using statistical tests and discussed the possible influence of athmospheric and topographic errors. To investigate the cause of the observed spatiotemporal deformation we employed an inverse source modelling approach, and simulated the dislocation source as an analytical pressurized spherical model. The inverted source can reproduce the observed deformation and allows to constrain the location of the magma reservoir under Llaima. Moreover we observed a signal might be associated to a slow landslide at the eastern flank of the volcano between December 2007 and Januar 2008. In

  16. Meta-Analysis of Data from the Submarine Ventilation Doctrine Test Program

    National Research Council Canada - National Science Library

    Hoover, J

    1998-01-01

    .... The Submarine Ventilation Doctrine Test Program was developed to address submarine-specific issues regarding the use of ventilation systems to control smoke and heat movement, maintain habitability...

  17. Volcanoes in Eruption - Set 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The word volcano is used to refer to the opening from which molten rock and gas issue from Earth's interior onto the surface, and also to the cone, hill, or mountain...

  18. Volcanoes in Eruption - Set 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The word volcano is used to refer to the opening from which molten rock and gas issue from Earth's interior onto the surface, and also to the cone, hill, or mountain...

  19. Decision Analysis Tools for Volcano Observatories

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2014-05-01

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

  1. Discerning Primary and Secondary Processes in the Volatile Geochemistry of Submarine Basalts

    Science.gov (United States)

    Hauri, E. H.

    2012-12-01

    Defining the primary volatile composition of submarine basalts from mid-ocean ridges, back-arc basins and arc-front volcanoes is key to understanding volatile cycling and the influence of volatiles on melting in the upper mantle. The volatile and halogen geochemistry of submarine volcanic glasses and melt inclusions has been the subject of an increasing number of studies that have made progress in distinguishing between secondary seawater contamination of magmas, and true melting and mantle-source variations, thus enabling observed magma compositions to be used to study the time-integrated cycling of volatiles through the upper mantle. But fewer studies have examined in detail the local-and segment-scale variations of volatiles together with trace elements and radiogenic isotopes, so that it can be understood how and where in the oceanic crust submarine magmas are contaminated by seawater-derived components. Mid-ocean ridge basalts (MORB) are significantly affected by secondary seawater assimilation processes due to their low volatile contents. From combined CO2-H2O-Cl systematics, it is apparent that addition of seawater-derived components is enhanced in magmas that ascend more slowly through the crust, and/or erupt away from the ridge axis. Highly depleted magmas that erupt in extensional zones within transform faults (e.g. Siqueiros) show little evidence for seawater addition, due to the near absence of thick crust and hydrothermal systems in such environments. At the same time, there also exists a second tier of more subtle seawater addition that is evident as a function of the extent of differentiation in MORB, pointing to combined assimilation and fractional crystallization as an important process operating in MORB petrogeneis. In detail the geochemistry of the assimilants can vary substantially from simple seawater compositions. Discerning seawater contamination in arc and back-arc magmas is more difficult, not only because of higher volatile concentrations

  2. The pattern of circumferential and radial eruptive fissures on the volcanoes of Fernandina and Isabela islands, Galapagos

    Science.gov (United States)

    Chadwick, W.W.; Howard, K.A.

    1991-01-01

    Maps of the eruptive vents on the active shield volcanoes of Fernandina and Isabela islands, Galapagos, made from aerial photographs, display a distinctive pattern that consists of circumferential eruptive fissures around the summit calderas and radial fissures lower on the flanks. On some volcano flanks either circumferential or radial eruptions have been dominant in recent time. The location of circumferential vents outside the calderas is independent of caldera-related normal faults. The eruptive fissures are the surface expression of dike emplacement, and the dike orientations are interpreted to be controlled by the state of stress in the volcano. Very few subaerial volcanoes display a pattern of fissures similar to that of the Galapagos volcanoes. Some seamounts and shield volcanoes on Mars morphologically resemble the Galapagos volcanoes, but more specific evidence is needed to determine if they also share common structure and eruptive style. ?? 1991 Springer-Verlag.

  3. Submarine earthquake rupture, active faulting and volcanism along the major Liquiñe-Ofqui Fault Zone and implications for seismic hazard assessment in the Patagonian Andes Ruptura sísmica submarina, tectónica y volcanismo activo a lo largo de la Falla Liquiñe-Ofqui e implicancias para el peligro sísmico en los Andes patagónicos

    Directory of Open Access Journals (Sweden)

    Gabriel Vargas

    2013-01-01

    Full Text Available The Liquiñe-Ofqui fault zone (LOFZ in the Patagonian Andes is an active major transpressional intra-arc fault system along which Quaternary faulting and volcanism develop. Subaerial and submarine geomorphologic and structural characterization of latest Pleistocene-Holocene faults and monogenetic volcanoes allows us to assess geological cartography of active faults and the kinematic model for recent tectonics during postglacial times, since 12,000 cal. years BP. This allows increasing the basic geological knowledge necessary for determining the seismic hazard associated with cortical structures in the Aysén region in southern Chile. Fault cartography and field observations suggest dominant dextral-reverse strike slip along north-south and locally NNW-striking faults, dextral-normal strike slip along NE to NNE- striking faults, and sinistral strike slip along east-west faults. This kinematics is consistent with regional SW-NE shortening in the context of a major transpressional fault zone. Holocene and even historic monogenetic and sub-aquatic volcanism occurred in this tectonic setting in a close spatial relationship and probably favored by the activity and local architecture of faults. Submarine fault scarps and deformed sediments observed at the bottom of the Aysén Fjord were associated with the destructive April 2007 Mw6.2 earthquake located along the LOFZ. Our observations show that this earthquake occurred along dextral 15-20 km long N-S structure named Punta Cola Fault (PCF. This fault system is located some kilometres to the east of the main N-S Río Cuervo Fault (RCF. Most of the epicentres of the seismic swarm during 2007 were located along or in between both structures. The study area is a transference zone between N-S regional branches of the LOFZ. The cartography of fault segments proposed here together with geophysical and geologic data suggest that large earthquakes Mw6.2-6.5 can be typically expected along most of the active

  4. Catalog of earthquake hypocenters at Alaskan volcanoes: January 1, 1994 through December 31, 1999

    Science.gov (United States)

    Jolly, Arthur D.; Stihler, Scott D.; Power, John A.; Lahr, John C.; Paskievitch, John; Tytgat, Guy; Estes, Steve; Lockhart, Andrew B.; Moran, Seth C.; McNutt, Stephen R.; Hammond, William R.

    2001-01-01

    The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute of the University of Alaska - Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, has maintained a seismic monitoring program at potentially active volcanoes in Alaska since 1988 (Power and others, 1993; Jolly and others, 1996). The primary objectives of this program are the seismic surveillance of active, potentially hazardous, Alaskan volcanoes and the investigation of seismic processes associated with active volcanism.Between 1994 and 1999, the AVO seismic monitoring program underwent significant changes with networks added at new volcanoes during each summer from 1995 through 1999. The existing network at Katmai –Valley of Ten Thousand Smokes (VTTS) was repaired in 1995, and new networks were installed at Makushin (1996), Akutan (1996), Pavlof (1996), Katmai - south (1996), Aniakchak (1997), Shishaldin (1997), Katmai - north (1998), Westdahl, (1998), Great Sitkin (1999) and Kanaga (1999). These networks added to AVO's existing seismograph networks in the Cook Inlet area and increased the number of AVO seismograph stations from 46 sites and 57 components in 1994 to 121 sites and 155 components in 1999. The 1995–1999 seismic network expansion increased the number of volcanoes monitored in real-time from 4 to 22, including Mount Spurr, Redoubt Volcano, Iliamna Volcano, Augustine Volcano, Mount Snowy, Mount Griggs, Mount Katmai, Novarupta, Trident Volcano, Mount Mageik, Mount Martin, Aniakchak Crater, Pavlof Volcano, Mount Dutton, Isanotski volcano, Shisaldin Volcano, Fisher Caldera, Westdahl volcano, Akutan volcano, Makushin Volcano, Great Sitkin volcano, and Kanaga Volcano (see Figures 1-15). The network expansion also increased the number of earthquakes located from about 600 per year in1994 and 1995 to about 3000 per year between 1997 and 1999.Highlights of the catalog period include: 1) a large volcanogenic seismic

  5. A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska

    Science.gov (United States)

    Brothers, Daniel; Haeussler, Peter J.; Lee Liberty,; David Finlayson,; Geist, Eric L.; Labay, Keith A.; Michael Byerly,

    2016-01-01

    During the 1964 Great Alaska earthquake (Mw 9.2), several fjords, straits, and bays throughout southern Alaska experienced significant tsunami runup of localized, but unexplained origin. Dangerous Passage is a glacimarine fjord in western Prince William Sound, which experienced a tsunami that devastated the village of Chenega where 23 of 75 inhabitants were lost – the highest relative loss of any community during the earthquake. Previous studies suggested the source of the devastating tsunami was either from a local submarine landslide of unknown origin or from coseismic tectonic displacement. Here we present new observations from high-resolution multibeam bathymetry and seismic reflection surveys conducted in the waters adjacent to the village of Chenega. The seabed morphology and substrate architecture reveal a large submarine landslide complex in water depths of 120–360 m. Analysis of bathymetric change between 1957 and 2014 indicates the upper 20–50 m (∼0.7 km3) of glacimarine sediment was destabilized and evacuated from the steep face of a submerged moraine and an adjacent ∼21 km2 perched sedimentary basin. Once mobilized, landslide debris poured over the steep, 130 m-high face of a deeper moraine and then blanketed the terminal basin (∼465 m water depth) in 11 ± 5 m of sediment. These results, combined with inverse tsunami travel-time modeling, suggest that earthquake- triggered submarine landslides generated the tsunami that struck the village of Chenega roughly 4 min after shaking began. Unlike other tsunamigenic landslides observed in and around Prince William Sound in 1964, the failures in Dangerous Passage are not linked to an active submarine delta. The requisite environmental conditions needed to generate large submarine landslides in glacimarine fjords around the world may be more common than previously thought. 

  6. Three Short Videos by the Yellowstone Volcano Observatory

    Science.gov (United States)

    Wessells, Stephen; Lowenstern, Jake; Venezky, Dina

    2009-01-01

    This is a collection of videos of unscripted interviews with Jake Lowenstern, who is the Scientist in Charge of the Yellowstone Volcano Observatory (YVO). YVO was created as a partnership among the U.S. Geological Survey (USGS), Yellowstone National Park, and University of Utah to strengthen the long-term monitoring of volcanic and earthquake unrest in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety. These video presentations give insights about many topics of interest about this area. Title: Yes! Yellowstone is a Volcano An unscripted interview, January 2009, 7:00 Minutes Description: USGS Scientist-in-Charge of Yellowstone Volcano Observatory, Jake Lowenstern, answers the following questions to explain volcanic features at Yellowstone: 'How do we know Yellowstone is a volcano?', 'What is a Supervolcano?', 'What is a Caldera?','Why are there geysers at Yellowstone?', and 'What are the other geologic hazards in Yellowstone?' Title: Yellowstone Volcano Observatory An unscripted interview, January 2009, 7:15 Minutes Description: USGS Scientist-in-Charge of Yellowstone Volcano Observatory, Jake Lowenstern, answers the following questions about the Yellowstone Volcano Observatory: 'What is YVO?', 'How do you monitor volcanic activity at Yellowstone?', 'How are satellites used to study deformation?', 'Do you monitor geysers or any other aspect of the Park?', 'Are earthquakes and ground deformation common at Yellowstone?', 'Why is YVO a relatively small group?', and 'Where can I get more information?' Title: Yellowstone Eruptions An unscripted interview, January 2009, 6.45 Minutes Description: USGS Scientist-in-Charge of Yellowstone Volcano Observatory, Jake Lowenstern, answers the following questions to explain volcanic

  7. Long-term in situ observations at the Athina mud volcano, Eastern Mediterranean: Taking the pulse of mud volcanism

    Science.gov (United States)

    Menapace, Walter; Völker, David; Sahling, Heiko; Zoellner, Christian; dos Santos Ferreira, Christian; Bohrmann, Gerhard; Kopf, Achim

    2017-11-01

    Long-term monitoring on mud volcanoes is fundamental to unravel episodic processes and transient changes that might otherwise be missed by using snapshot observations during time-limited research expeditions. We deployed a pore- and seafloor-pressure observatory close to the main conduit of the Athina mud volcano, south of Turkey (Eastern Mediterranean Sea), for a period of 26 months between February 2014 and April 2016. The observatory recorded 32 pore pressure transients related to as many seismic events (out of 625 earthquakes with Mw ≥ 2.5 occurred over the monitoring period in a radius of 1000 km) and few pore pressure excursions related to mud volcanism. The data helped to define a threshold for earthquake-triggered changes in mud volcano pore pressure, thus delineating possible pore pressure-distance relationships for different magnitudes ranges. Peak ground accelerations, as representative for earthquakes ground motion at the observatory have been calculated with different ground motion prediction equations. Using a conservative approach, an empirical equation has been identified, which specify the lowermost PGA necessary to induce a change in pore pressure record at the Athina mud volcano. Moreover, internal variations of the mud volcano system recordable through the pore pressure signal have been described for the first time in such a submarine feature.

  8. Spatial distribution of soil radon as a tool to recognize active faulting on an active volcano: the example of Mt. Etna (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Neri, Marco, E-mail: marco.neri@ct.ingv.it [Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma, 2 - 95123 Catania (Italy); Giammanco, Salvatore [Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma, 2 - 95123 Catania (Italy); Ferrera, Elisabetta; Patane, Giuseppe [Universita degli Studi di Catania, Dip. Scienze della Terra, Corso Italia, 52 - 95129 Catania (Italy); Zanon, Vittorio [Centro de Vulcanologia e Avaliacao de Riscos Geologicos - Universidade dos Acores, Rua Mae de Deus, 9501-801 Ponta Delgada (Portugal)

    2011-09-15

    This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquakes depth and intensity can give some hints on the source of gas and/or on fault dynamics. - Highlights: > We performed measurements of radon from soil carried out on Mt. Etna. > The sampled zone is characterized by the presence of numerous active faults. > Radon mapping reveal dangerous hidden faults buried by recent soil cover. > Our study gives some hints on the source of gas and on fault dynamics. > We recognized areas where radon activity represents a hazard to the population.

  9. Australia’s Submarine Design Capabilities and Capacities: Challenges and Options for the Future Submarine

    Science.gov (United States)

    2011-01-01

    General Dynamics Electric Boat Corporation EMC electromagnetic compatibility EMF electromagnetic field EMI electromagnetic interference EPCM engineering...to-diagnose flow-induced radiated noise Own-sensor performance degradation Note: Risks can be reduced for given designs using scale models...Acoustic analysis Addresses the total radiated noise signature of submarine designs Radiated noise that an enemy might detect Self-noise that that

  10. Nyiragongo Volcano before the Eruption

    Science.gov (United States)

    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

  11. Distribution and abundance of gas hydrates in near-surface deposits of the Håkon Mosby Mud Volcano, SW Barents Sea

    Science.gov (United States)

    Pape, Thomas; Feseker, Tomas; Kasten, Sabine; Fischer, David; Bohrmann, Gerhard

    2011-09-01

    The occurrence of gas hydrates at submarine mud volcanoes (MVs) located within the gas hydrate stability zone (GHSZ) is controlled by upward fluid and heat flux associated with MV activity. Determining the spatial distribution of gas hydrates at MVs is crucial to evaluate their sensitivity to known episodic changes in volcanic activity. We determined the hydrocarbon inventory and spatial distribution of hydrates at an individual MV structure. The Håkon Mosby Mud Volcano (HMMV), located at 1,250 m water depth on the Barents Sea slope, was investigated by combined pressure core sampling, heat flow measurements, and pore water chemical analysis. Quantitative pressure core degassing revealed gas-sediment ratios between 3.1 and 25.7, corresponding to hydrate concentrations of up to 21.3% of the pore volume. Hydrocarbon compositions and physicochemical conditions imply that gas hydrates incipiently crystallize as structure I hydrate, with a dissociation temperature of around 13.8°C at this water depth. Based on numerous in situ measurements of the geothermal gradient in the seabed, pore water sulfate profiles and microbathymetric data, we show that the thickness of the GHSZ increases from less than 1 m at the warm center to around 47 m in the outer parts of the HMMV. We estimate the total mass of hydrate-bound methane stored at the HMMV to be about 102.5 kt, of which 2.8 kt are located within the morphological Unit I around the center and thus are likely to be dissociated in the course of a large eruption.

  12. Deep long-period earthquakes beneath Washington and Oregon volcanoes

    Science.gov (United States)

    Nichols, M.L.; Malone, S.D.; Moran, S.C.; Thelen, W.A.; Vidale, J.E.

    2011-01-01

    Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN) triggered earthquake catalog for DLPs occurring between 1980 (when PNSN began collecting digital data) and October 2009. Through our analysis we identified 60 DLPs beneath six Cascade volcanic centers. No DLPs were associated with volcanic activity, including the 1980-1986 and 2004-2008 eruptions at Mount St. Helens. More than half of the events occurred near Mount Baker, where the background flux of magmatic gases is greatest among Washington and Oregon volcanoes. The six volcanoes with DLPs (counts in parentheses) are Mount Baker (31), Glacier Peak (9), Mount Rainier (9), Mount St. Helens (9), Three Sisters (1), and Crater Lake (1). No DLPs were identified beneath Mount Adams, Mount Hood, Mount Jefferson, or Newberry Volcano, although (except at Hood) that may be due in part to poorer network coverage. In cases where the DLPs do not occur directly beneath the volcanic edifice, the locations coincide with large structural faults that extend into the deep crust. Our observations suggest the occurrence of DLPs in these areas could represent fluid and/or magma transport along pre-existing tectonic structures in the middle crust. ?? 2010 Elsevier B.V.

  13. Geo-hazard by sediment mass movements in submarine canyons

    Science.gov (United States)

    Ghaith, Afif; Fakhri, Milad; Ivaldi, Roberta; Ciavola, Paolo

    2017-04-01

    Submarine mass movements and their consequences are of major concern for coastal communities and infrastructures but also for the exploitation and the development of seafloor resources. Elevated awareness of the need for better understanding of the underwater mass movement is coupled with great advances in underwater mapping technologies over the past two decades. The seafloor in the Nahr Ibrahim and Saida regions (Lebanon) is characterized by deep canyons, reaching one thousand meters depths in proximity of the coast. Signs of submarine mass movement instability related to these canyons create a connection between shallow and deep water. The presence of these canyons in a tectonically active area generates a particular drained mechanism to the sediment in form of mass movement and slumping. Identification of potential areas where slope movements could be triggered requires data with high spatial resolution. Since this area is poorly explored, in the framework of an international project between Lebanese Navy, Lebanese National Center for Marine Sciences, University of Ferrara and Italian Hydrographic Institute, we analyse the morpho-bathymetric and sedimentological characters of the coastal and shelf sectors. Multibeam echosounder and sub-bottom profiler acoustic systems calibrated with ground truths (sediment grab and core samples) allow us to characterize the nature of seafloor and sub-seafloor with particular detail to the geotechnical properties of sediments and high resolution seismic stratigraphy of the shallow layers. The detection of particular undersea features provides detail maps which are in support to littoral morpho-dynamics, coastal transport and sediment budget. Multilayer hydro-oceanographic map, referring to the seafloor dynamics in connection with deep water environment and drainage system, in accordance to the International Hydrographic Standards and nautical supports, are produced. This high resolution multibeam bathymetry dataset, integrated

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

    Science.gov (United States)

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

    2010-01-01

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

  15. The 1929 Grand Banks submarine landslide revisited

    Science.gov (United States)

    Schulten, Irena; Mosher, David C.; Krastel, Sebastian; Piper, David J. W.; Kienast, Markus

    2017-04-01

    On November 18th, 1929 a large submarine landslide occurred along the St. Pierre Slope of the southwestern Grand Banks of Newfoundland, as a result of a Mw 7.2 earthquake. This submarine landslide led to the first recognition of naturally-occurring submarine turbidity currents and is one of the few landslides known to have generated a tsunami. The event caused 28 causalities in Newfoundland and severe infrastructural damage. Earlier investigations of the area identified widely distributed shallow mass failures (15 - 20 m high escarpments), but no evidence of a larger headscarp. It is difficult to conceive, therefore, how this distributed shallow failure that rapidly evolved into a turbidity current would have generated a tsunami. It is hypothesised in this study that a deeper rooted sediment failure ( 500 m), involving faulting and mass-rotation, was involved in the sediment failure and this displacement generated the tsunami. In order to test this hypothesis, the volume and kinematics of the 1929 slope failure are analysed by means of recently acquired high resolution seismic reflection and multibeam swath bathymetry data, in addition to a significant volume of legacy data. The data allow determination of: 1) the dimension of the failure area, 2) the thickness and volume of failed sediment on St. Pierre Slope, 3) fault patterns and displacements, and 4) styles of sediment failure involved. Shallow (20 m high) sinuous escarpments and a number of faults are observed along the upper St. Pierre Slope (500 - 2 500 m water depth). The uppermost and largest of these escarpments shows association with a fault system. Preliminary results, therefore, indicate a complex sediment failure pattern along the St. Pierre Slope, possibly involving a deep-seated decollement and mobilization of a large volume of surficial sediment through retrogressive failure. Causes for the tsunami are yet to be determined.

  16. Marine litter in submarine canyons of the Bay of Biscay

    Science.gov (United States)

    van den Beld, Inge M. J.; Guillaumont, Brigitte; Menot, Lénaïck; Bayle, Christophe; Arnaud-Haond, Sophie; Bourillet, Jean-François

    2017-11-01

    Marine litter is a matter of increasing concern worldwide, from shallow seas to the open ocean and from beaches to the deep-seafloor. Indeed, the deep sea may be the ultimate repository of a large proportion of litter in the ocean. We used footage acquired with a Remotely Operated Vehicle (ROV) and a towed camera to investigate the distribution and composition of litter in the submarine canyons of the Bay of Biscay. This bay contains many submarine canyons housing Vulnerable Marine Ecosystems (VMEs) such as scleractinian coral habitats. VMEs are considered to be important for fish and they increase the local biodiversity. The objectives of the study were to investigate and discuss: (i) litter density, (ii) the principal sources of litter, (iii) the influence of environmental factors on the distribution of litter, and (iv) the impact of litter on benthic communities. Litter was found in all 15 canyons and at three sites on the edge of the continental shelf/canyon, in 25 of 29 dives. The Belle-île and Arcachon Canyons contained the largest amounts of litter, up to 12.6 and 9.5 items per 100 images respectively. Plastic items were the most abundant (42%), followed by fishing-related items (16%). The litter had both a maritime and a terrestrial origin. The main sources could be linked to fishing activities, major shipping lanes and river discharges. Litter appeared to accumulate at water depths of 801-1100 m and 1401-1700 m. In the deeper of these two depth ranges, litter accumulated on a geologically structured area, accounting for its high frequency at this depth. A larger number of images taken in areas of coral in the shallower of these two depth ranges may account for the high frequency of litter detection at this depth. A larger number of litter items, including plastic objects in particular, were observed on geological structures and in coral areas than on areas of bare substratum. The distribution of fishing-related items was similar for the various types of

  17. Newly recognized submarine slide complexes in the southern California Bight

    Science.gov (United States)

    Conrad, J. E.; Lee, H. J.; Edwards, B. D.; McGann, M.; Sliter, R. W.

    2012-12-01

    New high-resolution bathymetric and seismic-reflection surveys have imaged large (7) individual overlapping slides along the western margin of Santa Cruz Basin (SCB slide); 2) a series of slumps and slide scars on the slope south of San Pedro shelf (SPS slide); and 3) a slope failure along the shelf edge in northern San Diego County, termed the Del Mar slide. The SCB slide complex extends for 30 km along the western slope of Santa Cruz Basin, with debris lobes extending 5-8 km into the basin. Head scarps of some of these slides are 50-75 m high. The SPS slide complex also appears to consist of multiple slides, which roughly parallel the Palos Verdes Fault and the San Gabriel Canyon submarine channel on the shelf edge and slope south of San Pedro shelf. Slide deposits associated with this complex are only partially mapped due to limited high-resolution bathymetric coverage, but extend to the south in the area SW of Lasuen Knoll. Seismic-reflection profiles show that some of these deposits are up to 20 m thick. The Del Mar slide is located about 10 km north of La Jolla Canyon and extends about 6 km along the shelf edge. The head scarp lies along the trend of a branch of the Rose Canyon Fault Zone. Radiocarbon ages of sediment overlying this slide indicate the Del Mar slide is approximately 12-16 ka. These large slide complexes have several characteristics in common. Nearly all occur in areas of tectonic uplift. All of the complexes show evidence of recurrent slide activity, exhibiting multiple headwall scarps and debris lobes, and where available, high-resolution seismic-reflection profiles of these slide areas provide evidence of older, buried mass transport deposits. Assuming typical sedimentation rates, the recurrence interval of major slide events appears to be on the order of tens of thousands of years. Most of the slide complexes do not appear to be located in areas of high sediment input. The SCB and Del Mar slides are in areas receiving relatively small

  18. Multivariable Control System Design for a Submarine,

    Science.gov (United States)

    1984-05-01

    perturbations applied to the nominal point were identical in all cases (see table 2.3). The comparisons show excellent correlation between the...Open Loop Singular Values for the 5 and 1S Knot Linear Modelo *~~* b % % V’ , * % ~ .%~ C 9 ~ V. --.- V. V.-.--.--46..- S. 77’ Model S20R5 20- 10- -0...without imparting a pitch angle to the submarine and provides an excellent example of both the usefulness of w(t) as a state variable and the

  19. Hydrogen isotope systematics of submarine basalts

    Science.gov (United States)

    Kyser, T.K.; O'Neil, J.R.

    1984-01-01

    The D/H ratios and water contents in fresh submarine basalts from the Mid-Atlantic Ridge, the East Pacific Rise, and Hawaii indicate that the primary D/H ratios of many submarine lavas have been altered by processes including (1) outgassing, (2) addition of seawater at magmatic temperature, and (3) low-temperature hydration of glass. Decreases in ??D and H2O+ from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between ??D and H2O+ in basalts from the Galapagos Rise and the FAMOUS Area are attributed to outgassing of CH4 and H2. A good correlation between ??D values and H2O is observed in a suite of submarine tholeiites dredged from the Kilauea East Rift Zone where seawater (added directly to the magma), affected only the isotopic compositions of hydrogen and argon. Analyses of some glassy rims indicate that the outer millimeter of the glass can undergo lowtemperature hydration by hydroxyl groups having ??D values as low as -100. ??D values vary with H2O contents of subaerial transitional basalts from Molokai, Hawaii, and subaerial alkali basalts from the Society Islands, indicating that the primary ??D values were similar to those of submarine lavas. Extrapolations to possible unaltered ??D values and H2O contents indicate that the primary ??D values of most thoteiite and alkali basalts are near -80 ?? 5: the weight percentages of water are variable, 0.15-0.35 for MOR tholeiites, about 0.25 for Hawaiian tholeiites, and up to 1.1 for alkali basalts. The primary ??D values of -80 for most basalts are comparable to those measured for deep-seated phlogopites. These results indicate that hydrogen, in marked contrast to other elements such as Sr, Nd, Pb, and O, has a uniform isotopic composition in the mantle. This uniformity is best explained by the presence of a homogeneous reservoir of hydrogen that has existed in the mantle since the very early history of the Earth. ?? 1984.

  20. Analysis of Distribution of Volcanoes around the Korean Peninsula and the Potential Effects on Korea

    Science.gov (United States)

    Choi, Eun-kyeong; Kim, Sung-wook

    2017-04-01

    Since the scale and disaster characteristics of volcanic eruptions are determined by their geological features, it is important not only to grasp the current states of the volcanoes in neighboring countries around the Korean Peninsula, but also to analyze the tectonic settings, tectonic regions, geological features, volcanic types, and eruption histories of these volcanoes. Volcanic data were based on the volcano information registered with the Global Volcanism Program at the Smithsonian Institute. We created a database of 289 volcanoes around Korea, Japan, China, Taiwan, and the Kamchatka area in Russia, and then identified a high-risk group of 29 volcanoes that are highly likely to affect the region, based on conditions such as volcanic activity, types of rock at risk of eruption, distance from Seoul, and volcanoes having Plinian eruption history with volcanic explosivity index (VEI) of 4 or more. We selected 29 hazardous volcanoes, including Baekdusan, Ulleungdo, and 27 Japanese volcanoes that can cause widespread ashfall on the Korean peninsula by potentially explosive eruptions. In addition, we identified ten volcanoes that should be given the highest priority, through an analysis of data available in literature, such as volcanic ash dispersion results from previous Japanese eruptions, the definition of a large-scale volcano used by Japan's Cabinet Office, and examination of cumulative magma layer volumes from Japan's quaternary volcanoes. We expect that predicting the extent of the spread of ash caused by this hazardous activity and analyzing its impact on the Korean peninsula will be help to predict volcanic ash damage as well as provide direction for hazard mitigation research. Acknowledgements This research was supported by a grant [MPSS-NH-2015-81] through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government.

  1. Mauna Loa--history, hazards and risk of living with the world's largest volcano

    Science.gov (United States)

    Trusdell, Frank A.

    2012-01-01

    Mauna Loa on the Island Hawaiʻi is the world’s largest volcano. People residing on its flanks face many hazards that come with living on or near an active volcano, including lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and local tsunami (giant seawaves). The County of Hawaiʻi (Island of Hawaiʻi) is the fastest growing County in the State of Hawaii. Its expanding population and increasing development mean that risk from volcano hazards will continue to grow. U.S. Geological Survey (USGS) scientists at the Hawaiian Volcano Observatory (HVO) closely monitor and study Mauna Loa Volcano to enable timely warning of hazardous activity and help protect lives and property.

  2. Measuring Gases Using Drones at Turrialba Volcano, Costa Rica

    Science.gov (United States)

    Stix, J.; Alan, A., Jr.; Corrales, E.; D'Arcy, F.; de Moor, M. J.; Diaz, J. A.

    2016-12-01

    We are currently developing a series of drones and associated instrumentation to study Turrialba volcano in Costa Rica. This volcano has shown increasing activity during the last 20 years, and the volcano is currently in a state of heightened unrest as exemplified by recent explosive activity in May-August 2016. The eruptive activity has made the summit area inaccessible to normal gas monitoring activities, prompting development of new techniques to measure gas compositions. We have been using two drones, a DJI Spreading Wings S1000 octocopter and a Turbo Ace Matrix-i quadcopter, to airlift a series of instruments to measure volcanic gases in the plume of the volcano. These instruments comprise optical and electrochemical sensors to measure CO2, SO2, and H2S concentrations which are considered the most significant species to help forecast explosive eruptions and determine the relative proportions of magmatic and hydrothermal components in the volcanic gas. Additionally, cameras and sensors to measure air temperature, relative humidity, atmospheric pressure, and GPS location are included in the package to provide meteorological and geo-referenced information to complement the concentration data and provide a better picture of the volcano from a remote location. The integrated payloads weigh 1-2 kg, which can typically be flown by the drones in 10-20 minutes at altitudes of 2000-4000 meters. Preliminary tests at Turrialba in May 2016 have been very encouraging, and we are in the process of refining both the drones and the instrumentation packages for future flights. Our broader goals are to map gases in detail with the drones in order to make flux measurements of each species, and to apply this approach at other volcanoes.

  3. Global Volcano Proportional Economic Loss Risk Deciles

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Volcano Proportional Economic Loss Risk Deciles is a 2.5 minute grid of volcano hazard economic loss as proportions of Gross Domestic Product (GDP) per...

  4. Global Volcano Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Volcano Hazard Frequency and Distribution is a 2.5 minute gridded data set based upon the National Geophysical Data Center (NGDC) Volcano Database spanning...

  5. Global Volcano Mortality Risks and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Volcano Mortality Risks and Distribution is a 2.5 minute grid representing global volcano mortality risks. The data set was constructed using historical...

  6. Global Volcano Total Economic Loss Risk Deciles

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Volcano Total Economic Loss Risk Deciles is a 2.5 minute grid of global volcano total economic loss risks. First, subnational distributions of Gross Domestic...

  7. Collaborative Monitoring and Hazard Mitigation at Fuego Volcano, Guatemala

    Science.gov (United States)

    Lyons, J. J.; Bluth, G. J.; Rose, W. I.; Patrick, M.; Johnson, J. B.; Stix, J.

    2007-05-01

    A portable, digital sensor network has been installed to closely monitor changing activity at Fuego volcano, which takes advantage of an international collaborative effort among Guatemala, U.S. and Canadian universities, and the Peace Corps. The goal of this effort is to improve the understanding shallow internal processes, and consequently to more effectively mitigate volcanic hazards. Fuego volcano has had more than 60 historical eruptions and nearly-continuous activity make it an ideal laboratory to study volcanic processes. Close monitoring is needed to identify base-line activity, and rapidly identify and disseminate changes in the activity which might threaten nearby communities. The sensor network is comprised of a miniature DOAS ultraviolet spectrometer fitted with a system for automated plume scans, a digital video camera, and two seismo-acoustic stations and portable dataloggers. These sensors are on loan from scientists who visited Fuego during short field seasons and donated use of their sensors to a resident Peace Corps Masters International student from Michigan Technological University for extended data collection. The sensor network is based around the local volcano observatory maintained by Instituto National de Sismologia, Vulcanologia, Metrologia e Hidrologia (INSIVUMEH). INSIVUMEH provides local support and historical knowledge of Fuego activity as well as a secure location for storage of scientific equipment, data processing, and charging of the batteries that power the sensors. The complete sensor network came online in mid-February 2007 and here we present preliminary results from concurrent gas, seismic, and acoustic monitoring of activity from Fuego volcano.

  8. Risk assessment in submarine outfall projects: the case of Portugal.

    Science.gov (United States)

    Mendonça, Ana; Losada, Miguel Ángel; Reis, Maria Teresa; Neves, Maria Graça

    2013-02-15

    Submarine outfalls need to be evaluated as part of an integrated environmental protection system for coastal areas. Although outfalls are tight with the diversity of economic activities along a densely populated coastline being effluent treatment and effluent reuse a sign of economic prosperity, precautions must be taken in the construction of these structures. They must be designed so as to have the least possible impact on the environment and at the same time be economically viable. This paper outlines the initial phases of a risk assessment procedure for submarine outfall projects. This approach includes a cost-benefit analysis in which risks are systematically minimized or eliminated. The methods used in this study also allow for randomness and uncertainty. The input for the analysis is a wide range of information and data concerning the failure probability of outfalls and the consequences of an operational stoppage or failure. As part of this risk assessment, target design levels of reliability, functionality, and operationality were defined for the outfalls. These levels were based on an inventory of risks associated with such construction projects, and thus afforded the possibility of identifying possible failure modes. This assessment procedure was then applied to four case studies in Portugal. The results obtained were the values concerning the useful life of the outfalls at the four sites and their joint probability of failure against the principal failure modes assigned to ultimate and serviceability limit states. Also defined were the minimum operationality of these outfalls, the average number of admissible technical breakdowns, and the maximum allowed duration of a stoppage mode. It was found that these values were in consonance with the nature of the effluent (tourist-related, industrial, or mixed) as well as its importance for the local economy. Even more important, this risk assessment procedure was able to measure the impact of the outfalls on

  9. Flow dynamics around downwelling submarine canyons

    Directory of Open Access Journals (Sweden)

    J. M. Spurgin

    2014-10-01

    Full Text Available Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (northwestern Mediterranean was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby and Burger numbers were used to determine the significance of Coriolis acceleration and stratification (respectively and their impacts on flow dynamics. A new non-dimensional parameter (χ was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10-day model period; however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation, and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. The offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m. Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate, as well as stronger vorticity within the canyon. Results from previous studies are explained within this new dynamic framework.

  10. Submarine Tailings Disposal (STD—A Review

    Directory of Open Access Journals (Sweden)

    Bernhard Dold

    2014-07-01

    Full Text Available The mining industry is a fundamental industry involved in the development of modern society, but is also the world’s largest waste producer. This role will be enhanced in the future, because ore grades are generally decreasing, thus leading to increases in the waste/metal production ratio. Mine wastes deposited on-land in so-called tailings dams, impoundments or waste-dumps have several associated environmental issues that need to be addressed (e.g., acid mine drainage formation due to sulphide oxidation, geotechnical stability, among others, and social concerns due to land use during mining. The mining industry recognizes these concerns and is searching for waste management alternatives for the future. One option used in the past was the marine shore or shallow submarine deposition of this waste material in some parts of the world. After the occurrence of some severe environmental pollution, today the deposition in the deep sea (under constant reducing conditions is seen as a new, more secure option, due to the general thought that sulphide minerals are geochemically stable under the reduced conditions prevailing in the deep marine environment. This review highlights the mineralogical and geochemical issues (e.g., solubility of sulphides in seawater; reductive dissolution of oxide minerals under reducing conditions, which have to be considered when evaluating whether submarine tailings disposal is a suitable alternative for mine waste.

  11. Submarine melt rates under Greenland's ice tongues

    Science.gov (United States)

    Wilson, Nat; Straneo, Fiametta; Heimbach, Patrick; Cenedese, Claudia

    2017-04-01

    The few remaining ice tongues (ice-shelf like extensions) of Greenland's glaciers are undergoing rapid changes with potential implications for the stability of the ice sheet. Submarine melting is recognized as a major contributor to mass loss, yet the magnitude and spatial distribution of melt are poorly known or understood. Here, we use high resolution satellite imagery to infer the magnitude and spatial variability of melt rates under Greenland's largest remaining ice tongues: Ryder Glacier, Petermann Glacier and Nioghalvfjerdsbræ (79 North Glacier). We find that submarine plus aerial melt approximately balance the ice flux from the grounded ice sheet for the first two while at Nioghalvfjerdsbræ the total melt flux exceeds the inflow of ice indicating thinning of the ice tongue. We also show that melt rates under the ice tongues vary considerably, exceeding 60 m yr-1 near the grounding zone and decaying rapidly downstream. Channels, likely originating from upstream subglacial channels, give rise to large melt variations across the ice tongues. Using derived melt rates, we test simplified melt parameterizations appropriate for ice sheet models and find the best agreement with those that incorporate ice tongue geometry in the form of depth and slope.

  12. Machine Learning Method for Pattern Recognition in Volcano Seismic Spectra

    Science.gov (United States)

    Radic, V.; Unglert, K.; Jellinek, M.

    2016-12-01

    Variations in the spectral content of volcano seismicity related to changes in volcanic activity are commonly identified manually in spectrograms. However, long time series of monitoring data at volcano observatories require tools to facilitate automated and rapid processing. Techniques such as Self-Organizing Maps (SOM), Principal Component Analysis (PCA) and clustering methods can help to quickly and automatically identify important patterns related to impending eruptions. In this study we develop and evaluate an algorithm applied on a set of synthetic volcano seismic spectra as well as observed spectra from Kılauea Volcano, Hawai`i. Our goal is to retrieve a set of known spectral patterns that are associated with dominant phases of volcanic tremor before, during, and after periods of volcanic unrest. The algorithm is based on training a SOM on the spectra and then identifying local maxima and minima on the SOM 'topography'. The topography is derived from the first two PCA modes so that the maxima represent the SOM patterns that carry most of the variance in the spectra. Patterns identified in this way reproduce the known set of spectra. Our results show that, regardless of the level of white noise in the spectra, the algorithm can accurately reproduce the characteristic spectral patterns and their occurrence in time. The ability to rapidly classify spectra of volcano seismic data without prior knowledge of the character of the seismicity at a given volcanic system holds great potential for real time or near-real time applications, and thus ultimately for eruption forecasting.

  13. Pattern recognition in volcano seismology - Reducing spectral dimensionality

    Science.gov (United States)

    Unglert, K.; Radic, V.; Jellinek, M.

    2015-12-01

    Variations in the spectral content of volcano seismicity can relate to changes in volcanic activity. Low-frequency seismic signals often precede or accompany volcanic eruptions. However, they are commonly manually identified in spectra or spectrograms, and their definition in spectral space differs from one volcanic setting to the next. Increasingly long time series of monitoring data at volcano observatories require automated tools to facilitate rapid processing and aid with pattern identification related to impending eruptions. Furthermore, knowledge transfer between volcanic settings is difficult if the methods to identify and analyze the characteristics of seismic signals differ. To address these challenges we evaluate whether a machine learning technique called Self-Organizing Maps (SOMs) can be used to characterize the dominant spectral components of volcano seismicity without the need for any a priori knowledge of different signal classes. This could reduce the dimensions of the spectral space typically analyzed by orders of magnitude, and enable rapid processing and visualization. Preliminary results suggest that the temporal evolution of volcano seismicity at Kilauea Volcano, Hawai`i, can be reduced to as few as 2 spectral components by using a combination of SOMs and cluster analysis. We will further refine our methodology with several datasets from Hawai`i and Alaska, among others, and compare it to other techniques.

  14. Geoheritage value of the UNESCO site at Leon Viejo and Momotombo volcano, Nicaragua

    Science.gov (United States)

    van Wyk de Vries, Benjamin; Navarro, Martha; Espinoza, Eveling; Delgado, Hugo

    2017-04-01

    The Momotombo volcano has a special place in the history of Nicaragua. It is perfectly visible from the Capital, Managua, and from the major city of Leon. The old capital "Leon Viejo", founded in 1524 was abandoned in 1610, after a series of earthquakes and some major eruptions from Momotombo. The site was subsequently covered by Momotombo ash. A major geothermal power plant stands at the base of the volcano. Momotombo had been dormant for a hundred years, but had maintained high fumarole temperatures (900°C), indicating magma had been close to the surface for decades. In recent years, seismic activity has increased around the volcano. In December 2015, after a short ash eruption phase the volcano erupted lava, then a string of Vulcanian explosions. The volcano is now in a phase of small Vulcanian explosions and degassing. The Leon Viejo World Heritage site is at risk to mainly ash fall from the volcano, but the abandonment of the old city was primarily due to earthquakes. Additional risks come from high rainfall during hurricanes. There is an obvious link between the cultural site (inscribed under UNESCO cultural criteria) and the geological environment. First, the reactivation of Momotombo volcano makes it more important to revise the hazard of the site. At the same time, Leon Viejo can provide a portal for outreach related to the volcano and for geological risk in general. To maximise this, we provide a geosite inventory of the main features of Momotombo, and it's environs, that can be used as the first base for such studies. The volcano was visited by many adventure tourists before the 2015/2016 eruption, but is out of bounds at present. Alternative routes, around the volcano could be made, to adapt to the new situation and to show to visitors more of the geodiversity of this fascinating volcano-tectonic and cultural area.

  15. Space Radar Image of Kiluchevskoi, Volcano, Russia

    Science.gov (United States)

    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

  16. What threat do turbidity currents and submarine landslides pose to submarine telecommunications cable infrastructure?

    Science.gov (United States)

    Clare, Michael; Pope, Edward; Talling, Peter; Hunt, James; Carter, Lionel

    2016-04-01

    The global economy relies on uninterrupted usage of a network of telecommunication cables on the seafloor. These submarine cables carry ~99% of all trans-oceanic digital data and voice communications traffic worldwide, as they have far greater bandwidth than satellites. Over 9 million SWIFT banks transfers alone were made using these cables in 2004, totalling 7.4 trillion of transactions per day between 208 countries, which grew to 15 million SWIFT bank transactions last year. We outline the challenge of why, how often, and where seafloor cables are broken by natural causes; primarily subsea landslides and sediment flows (turbidity currents and also debris flows and hyperpycnal flows). These slides and flows can be very destructive. As an example, a sediment flow in 1929 travelled up to 19 m/s and broke 11 cables in the NE Atlantic, running out for ~800 km to the abyssal ocean. The 2006 Pingtung earthquake triggered a sediment flow that broke 22 cables offshore Taiwan over a distance of 450 km. Here, we present initial results from the first statistical analysis of a global database of cable breaks and causes. We first investigate the controls on frequency of submarine cable breaks in different environmental and geological settings worldwide. We assess which types of earthquake pose a significant threat to submarine cable networks. Meteorological events, such as hurricanes and typhoons, pose a significant threat to submarine cable networks, so we also discuss the potential impacts of future climate change on the frequency of such hazards. We then go on to ask what are the physical impacts of submarine sediment flows on submerged cables? A striking observation from past cable breaks is sometimes cables remain unbroken, whilst adjacent cables are severed (and record powerful flows travelling at up to 6 m/s). Why are some cables broken, but neighbouring cables remain intact? We provide some explanations for this question, and outline the need for future in

  17. Volcano Hazards - A National Threat

    Science.gov (United States)

    ,

    2006-01-01

    When the violent energy of a volcano is unleashed, the results are often catastrophic. The risks to life, property, and infrastructure from volcanoes are escalating as more and more people live, work, play, and travel in volcanic regions. Since 1980, 45 eruptions and 15 cases of notable volcanic unrest have occurred at 33 U.S. volcanoes. Lava flows, debris avalanches, and explosive blasts have invaded communities, swept people to their deaths, choked major riverways, destroyed bridges, and devastated huge tracts of forest. Noxious volcanic gas emissions have caused widespread lung problems. Airborne ash clouds have disrupted the health, lives, and businesses of hundreds of thousands of people; caused millions of dollars of aircraft damage; and nearly brought down passenger flights.

  18. Deep intrusions, lateral magma transport and related uplift at ocean island volcanoes

    Science.gov (United States)

    Klügel, Andreas; Longpré, Marc-Antoine; García-Cañada, Laura; Stix, John

    2015-12-01

    Oceanic intraplate volcanoes grow by accumulation of erupted material as well as by coeval or discrete magmatic intrusions. Dykes and other intrusive bodies within volcanic edifices are comparatively well studied, but intrusive processes deep beneath the volcanoes remain elusive. Although there is geological evidence for deep magmatic intrusions contributing to volcano growth through uplift, this has rarely been demonstrated by real-time monitoring. Here we use geophysical and petrological data from El Hierro, Canary Islands, to show that intrusions from the mantle and subhorizontal transport of magma within the oceanic crust result in rapid endogenous island growth. Seismicity and ground deformation associated with a submarine eruption in 2011-2012 reveal deep subho