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Sample records for active submarine volcanoes

  1. Active submarine volcano sampled

    USGS Publications Warehouse

    Taylor, B.

    1983-01-01

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

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

    USGS Publications Warehouse

    Embley, R.W.; Chadwick, W.W.; Baker, E.T.; Butterfield, D.A.; Resing, J.A.; De Ronde, C. E. J.; Tunnicliffe, V.; Lupton, J.E.; Juniper, S.K.; Rubin, K.H.; Stern, R.J.; Lebon, G.T.; Nakamura, K.-I.; Merle, S.G.; Hein, J.R.; Wiens, D.A.; Tamura, Y.

    2006-01-01

    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. ?? 2006 Nature Publishing Group.

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

    PubMed

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

    PubMed Central

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

    2016-01-01

    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 3He/4He 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 3He/4He signature of at least 7.0 Ra (being Ra the 3He/4He 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 3He/4He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano. PMID:27311383

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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 3He/4He 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 3He/4He signature of at least 7.0 Ra (being Ra the 3He/4He 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 3He/4He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano.

  6. High-resolution seismic structure analysis of an active submarine mud volcano area off SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Hsiao-Shan; Hsu, Shu-Kun; Tsai, Wan-Lin; Tsai, Ching-Hui; Lin, Shin-Yi; Chen, Song-Chuen

    2015-04-01

    In order to better understand the subsurface structure related to an active mud volcano MV1 and to understand their relationship with gas hydrate/cold seep formation, we conducted deep-towed side-scan sonar (SSS), sub-bottom profiler (SBP), multibeam echo sounding (MBES), and multi-channel reflection seismic (MCS) surveys off SW Taiwan from 2009 to 2011. As shown in the high-resolution sub-bottom profiler and EK500 sonar data, the detailed structures reveal more gas seeps and gas flares in the study area. In addition, the survey profiles show several submarine landslides occurred near the thrust faults. Based on the MCS results, we can find that the MV1 is located on top of a mud diapiric structure. It indicates that the MV1 has the same source as the associated mud diapir. The blanking of the seismic signal may indicate the conduit for the upward migration of the gas (methane or CO2). Therefore, we suggest that the submarine mud volcano could be due to a deep source of mud compressed by the tectonic convergence. Fluids and argillaceous materials have thus migrated upward along structural faults and reach the seafloor. The gas-charged sediments or gas seeps in sediments thus make the seafloor instable and may trigger submarine landslides.

  7. Long-term explosive degassing and debris flow activity at West Mata submarine volcano

    NASA Astrophysics Data System (ADS)

    Dziak, R. P.; Bohnenstiehl, D. R.; Baker, E. T.; Matsumoto, H.; Caplan-Auerbach, J.; Embley, R. W.; Merle, S. G.; Walker, S. L.; Lau, T.-K.; Chadwick, W. W.

    2015-03-01

    West Mata is a 1200 m deep submarine volcano where explosive boninite eruptions were observed in 2009. The acoustic signatures from the volcano's summit eruptive vents Hades and Prometheus were recorded with an in situ (~25 m range) hydrophone during ROV dives in May 2009 and with local (~5 km range) moored hydrophones between December 2009 and August 2011. The sensors recorded low frequency (1-40 Hz), short duration explosions consistent with magma bubble bursts from Hades, and broadband, 1-5 min duration signals associated with episodes of fragmentation degassing from Prometheus. Long-term eruptive degassing signals, recorded through May 2010, preceded a several month period of declining activity. Degassing episodes were not recorded acoustically after early 2011, although quieter effusive eruption activity may have continued. Synchronous optical measurements of turbidity made between December 2009 and April 2010 indicate that turbidity maxima resulted from occasional south flank slope failures triggered by the collapse of accumulated debris during eruption intervals.

  8. The Submarine Flanks of Anatahan Volcano

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    submarine volcano located about 10 km NE of the island, here named NE Anatahan volcano. The summit of NE Anatahan volcano reaches a depth of 459 m, and the depth of the saddle between NE Anatahan and the submarine flank of Anatahan is 1000 m. NE Anatahan volcano has a circular crater rim that is open to the west. The summit and northern flank of NE Anatahan volcano are cut by normal faults that trend north-south, possibly reflecting the orientation of the local tectonic stress field. Another submarine volcanic construction is located 5 miles north of the island and is a linear ridge aligned in the NNW-SSE direction. This ridge has a crest at a depth of 1000 m, and the most recent deposits from Anatahan and NE Anatahan volcanoes are deflected around it. There is no evidence of any landslide materials on the submarine flanks of Anatahan, except perhaps for a small area southeast of NE Anatahan volcano. Even though there appears to be evidence for relatively young submarine eruptions at Anatahan, there has been no reported evidence for submarine volcanic activity during the 2003 eruption.

  9. Esmeralda Bank: Geochemistry of an active submarine volcano in the Mariana Island Arc

    NASA Astrophysics Data System (ADS)

    Stern, Robert J.; Bibee, L. D.

    1984-05-01

    Esmeralda Bank is the southernmost active volcano in the Izu-Volcano-Mariana Arc. This submarine volcano is one of the most active vents in the western Pacific. It has a total volume of about 27 km3, rising to within 30 m of sea level. Two dredge hauls from Esmeralda recovered fresh, nearly aphyric, vesicular basalts and basaltic andesites and minor basaltic vitrophyre. These samples reflect uniform yet unusual major and trace element chemistries. Mean abundances of TiO2 (1.3%) and FeO* (12.6%) are higher and CaO (9.2%) and Al2O3 (15.1%) are lower than rocks of similar silica content from other active Mariana Arc volcanoes. Mean incompatible element ratios K/Rb (488) and K/Ba (29) of Esmeralda rocks are indistinguishable from those of other Mariana Arc volcanoes. On a Ti-Zr plot, Esmeralda samples plot in the field of oceanic basalts while other Mariana Arc volcanic rocks plot in the field for island arcs. Incompatible element ratios K/Rb and K/Ba and isotopic compositions of Sr (87Sr/86Sr=0.70342 0.70348), Nd (ɛND=+7.6 to +8.1), and O(δ18O=+5.8 to +5.9) are incompatible with models calling for the Esmeralda source to include appreciable contributions from pelagic sediments or fresh or altered abyssal tholeiite from subduction zone melting. Instead, incompatible element and isotopic ratios of Esmeralda rocks are similar to those of intra-plate oceanic islands or “hot-spot” volcanoes in general and Kilauean tholeiites in particular. The conclusion that the source for Esmeralda lavas is an ocean-island type mantle reservoir is preferred. Esmeralda Bank rare earth element patterns are inconsistent with models calling for residual garnet in the source region, but are adequately modelled by 7 10% equilibrium partial melting of spinel lherzolite. This is supported by consideration of the results of melting experiments at 20 kbars, 1,150° C with CO2 and H2O as important volatile components. These experiments further indicate that low MgO (4.1%), MgO/FeO*(0.25) and

  10. The study of active submarine volcanoes and hydrothermal vents in the Southernmost Part of Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Tsai, C.; Lee, C.

    2004-12-01

    The study area is located in the Southernmost Part of Okinawa Trough (SPOT), which is a back-arc basin formed by extension of Eurasian plate. Previous research indicated two extensional stages in SPOT area. Many normal-fault structures were come into existence during both extensional processes. The SPOT is presently in an activity tectonic episode. Therefore, the area becomes a frequent earthquake and abundant magmatism. The purpose of this study is to discuss which relationship between tectonics, submarine volcanoes and hydrothermal vents in SPOT area. The investigations are continued from 1998 to 2004, we have found at least twelve active hydrothermal vents in study area. Compare the locations hydrothermal vents with fault systems, we find both of them have highly correlated. We can distinguish them into two shapes, pyramidal shape and non-pyramidal shape. According to plumes height, we are able to divide these vents into two groups near east longitude 122.5° . East of this longitude, the hydrothermal plumes are more powerful and west of it are the weaker. This is closely related to the present extensional axis (N80° E) of the southern part of the Okinawa Trough. This can be explained the reason of why the more powerful vents coming out of the east group. The east group is associated with the present back-arc spreading system. West of 122.5° , the spreading system are in a primary stage. The andesitic volcanic island, the Turtle Island, is a result of N60° E extensional tectonism with a lot of faults. Besides the pyramidal shape, this can be proved indirectly. The vents located in the west side were occurred from previous extensional faults and are weaker than the eastern. Therefore, we suggest that if last the extension keeps going on, the hydrothermal vents located at the west side of the longitude 122.5° will be intensified.

  11. Numerical Tsunami Hazard Assessment of the Only Active Lesser Antilles Arc Submarine Volcano: Kick 'em Jenny.

    NASA Astrophysics Data System (ADS)

    Dondin, F. J. Y.; Dorville, J. F. M.; Robertson, R. E. A.

    2015-12-01

    The Lesser Antilles Volcanic Arc has potentially been hit by prehistorical regional tsunamis generated by voluminous volcanic landslides (volume > 1 km3) among the 53 events recognized so far. No field evidence of these tsunamis are found in the vincity of the sources. Such a scenario taking place nowadays would trigger hazardous tsunami waves bearing potentially catastrophic consequences for the closest islands and regional offshore oil platforms.Here we applied a complete hazard assessment method on the only active submarine volcano of the arc Kick 'em Jenny (KeJ). KeJ is the southernmost edifice with recognized associated volcanic landslide deposits. From the three identified landslide episodes one is associated with a collapse volume ca. 4.4 km3. Numerical simulations considering a single pulse collapse revealed that this episode would have produced a regional tsunami. An edifice current volume estimate is ca. 1.5 km3.Previous study exists in relationship to assessment of regional tsunami hazard related to shoreline surface elevation (run-up) in the case of a potential flank collapse scenario at KeJ. However this assessment was based on inferred volume of collapse material. We aim to firstly quantify potential initial volumes of collapse material using relative slope instability analysis (RSIA); secondly to assess first order run-ups and maximum inland inundation distance for Barbados and Trinidad and Tobago, i.e. two important economic centers of the Lesser Antilles. In this framework we present for seven geomechanical models tested in the RSIA step maps of critical failure surface associated with factor of stability (Fs) for twelve sectors of 30° each; then we introduce maps of expected potential run-ups (run-up × the probability of failure at a sector) at the shoreline.The RSIA evaluates critical potential failure surface associated with Fs <1 as compared to areas of deficit/surplus of mass/volume identified on the volcanic edifice using (VolcanoFit 2

  12. A Submarine Perspective on Hawaiian Volcanoes

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Postwar improvements in navigation, sonar-based mapping, and submarine photography enabled the development of bathymetric maps, which revealed submarine morphologic features that could be dredged or explored and sampled with a new generation of manned and unmanned submersibles. The maps revealed debris fields from giant landslides, the great extent of rift zones radiating from volcanic centers, and two previously unknown submarine volcanoes named Mahukona and Loihi, the youngest Hawaiian volcano. About 70 major landslides cover half the flanks of the Hawaiian Ridge out to Midway Island. Some of the landslides attain lengths of 200 km and have volumes exceeding 5,000 km3. More recent higher resolution bathymetry and sidescan data reveal that many submarine eruptions construct circular, flat-topped, monogenetic cones; that large fields of young strongly alkalic lava flows, such as the North Arch and South Arch lava fields, erupt on the seafloor within several hundred km of the islands; and that alkalic lavas erupt during the shield stage on Kilauea and Mauna Loa. The North Arch flow field covers about 24,000 km2, has an estimated volume between about 1000 and 1250 km3, has flows as long as 108 km, and erupted from over 100 vents. The source and melting mechanisms for their production is still debated. The maps also displayed stair-step terraces, mostly constructed of drowned coral reefs, which form during early rapid subsidence of the volcanoes during periods of oscillating sea level. The combination of scuba and underwater photography facilitated the first motion pictures of the mechanism of formation of pillow lava in shallow water offshore Kilauea. The age progression known from the main islands was extended westward along the Hawaiian Ridge past Midway Island, around a bend in the chain and northward along the Emperor Seamounts. Radiometric dating of dredged samples from these submarine volcanoes show that the magma source that built the chain has been active for

  13. Mineralized microbes from Giggenbach submarine volcano

    NASA Astrophysics Data System (ADS)

    Jones, Brian; de Ronde, C. E. J.; Renaut, Robin W.

    2008-08-01

    The Giggenbach submarine volcano, which forms part of the Kermadec active arc front, is located ˜780 km NNE of the North Island of New Zealand. Samples collected from chimneys associated with seafloor hydrothermal vents on this volcano, at a depth of 160-180 m, contain silicified microbes and microbes entombed in reticular Fe-rich precipitates. The mineralized biota includes filamentous, rod-shaped, and rare coccoid microbes. In the absence of organic carbon for rDNA analysis or preserved cells, the taxonomic affinity of these microbes, in terms of extant taxa, remains questionable because of their architectural simplicity and the paucity of taxonomically significant features. The three-dimensional preservation of the microbes indicates rapid mineralization with a steady supply of supersaturated fluids to the nucleation sites present on the surfaces of the microbes. The mineralization styles evident in the microbes from the Giggenbach submarine volcano are similar to those associated with mineralized microbes found in terrestrial hot spring deposits in New Zealand, Iceland, Yellowstone, and Kenya. These similarities exist even though the microbes are probably different and the fluids become supersaturated with respect to opal-A by different mechanisms. For ancient rocks it means that interpretations of the depositional settings cannot be based solely on the silicified microbes or their style of silicification.

  14. Unusual seismic activity in 2011 and 2013 at the submarine volcano Rocard, Society hot spot (French Polynesia)

    NASA Astrophysics Data System (ADS)

    Talandier, Jacques; Hyvernaud, Olivier; Maury, René C.

    2016-05-01

    We analyze two seismic events that occurred on 27 May 2011 and 29 April 2013 at the Rocard submarine volcano which overlies the Society hot spot. The Polynesian Seismic Network recorded for the first time unusual associated short- and long-period signals, with perfectly monochromatic (0.0589 Hz) Rayleigh wave trains of long period and duration. None of the numerous observations of long-period (10-30 s) signals previously associated with volcanic activity in Japan, Italy, Mexico, Indonesia, Antarctica, and the Hawaiian Islands have the characteristics we observed at Rocard. We propose a tentative model for these unusual and rather enigmatic signals, in which the movement of lava excited the resonance of a shallow open conduit under a high hydrostatic pressure of ~400 bars.

  15. Vailulu’u Seamount, Samoa: Life and death on an active submarine volcano

    PubMed Central

    Staudigel, Hubert; Hart, Stanley R.; Pile, Adele; Bailey, Bradley E.; Baker, Edward T.; Brooke, Sandra; Connelly, Douglas P.; Haucke, Lisa; German, Christopher R.; Hudson, Ian; Jones, Daniel; Koppers, Anthony A. P.; Konter, Jasper; Lee, Ray; Pietsch, Theodore W.; Tebo, Bradley M.; Templeton, Alexis S.; Zierenberg, Robert; Young, Craig M.

    2006-01-01

    Submersible exploration of the Samoan hotspot revealed a new, 300-m-tall, volcanic cone, named Nafanua, in the summit crater of Vailulu’u seamount. Nafanua grew from the 1,000-m-deep crater floor in <4 years and could reach the sea surface within decades. Vents fill Vailulu’u crater with a thick suspension of particulates and apparently toxic fluids that mix with seawater entering from the crater breaches. Low-temperature vents form Fe oxide chimneys in many locations and up to 1-m-thick layers of hydrothermal Fe floc on Nafanua. High-temperature (81°C) hydrothermal vents in the northern moat (945-m water depth) produce acidic fluids (pH 2.7) with rising droplets of (probably) liquid CO2. The Nafanua summit vent area is inhabited by a thriving population of eels (Dysommina rugosa) that feed on midwater shrimp probably concentrated by anticyclonic currents at the volcano summit and rim. The moat and crater floor around the new volcano are littered with dead metazoans that apparently died from exposure to hydrothermal emissions. Acid-tolerant polychaetes (Polynoidae) live in this environment, apparently feeding on bacteria from decaying fish carcasses. Vailulu’u is an unpredictable and very active underwater volcano presenting a potential long-term volcanic hazard. Although eels thrive in hydrothermal vents at the summit of Nafanua, venting elsewhere in the crater causes mass mortality. Paradoxically, the same anticyclonic currents that deliver food to the eels may also concentrate a wide variety of nektonic animals in a death trap of toxic hydrothermal fluids. PMID:16614067

  16. Voluminous submarine lava flows from Hawaiian volcanoes

    SciTech Connect

    Holcomb, R.T.; Moore, J.G.; Lipman, P.W.; Belderson, R.H.

    1988-05-01

    The GLORIA long-range sonar imaging system has revealed fields of large lava flows in the Hawaiian Trough east and south of Hawaii in water as deep as 5.5 km. Flows in the most extensive field (110 km long) have erupted from the deep submarine segment of Kilauea's east rift zone. Other flows have been erupted from Loihi and Mauna Loa. This discovery confirms a suspicion, long held from subaerial studies, that voluminous submarine flows are erupted from Hawaiian volcanoes, and it supports an inference that summit calderas repeatedly collapse and fill at intervals of centuries to millenia owing to voluminous eruptions. These extensive flows differ greatly in form from pillow lavas found previously along shallower segments of the rift zones; therefore, revision of concepts of volcano stratigraphy and structure may be required.

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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.

  19. Debris Avalanche Formation at Kick'em Jenny Submarine Volcano

    NASA Astrophysics Data System (ADS)

    Sigurdsson, H.; Carey, S. N.; Wilson, D.

    2005-12-01

    Kick'em Jenny submarine volcano near Grenada is the most active volcanic center in the Lesser Antilles arc. Multibeam surveys of the volcano by NOAA in 2002 revealed an arcuate fault scarp east of the active cone, suggesting flank collapse. More extensive NOAA surveys in 2003 demonstrated the presence of an associated debris avalanche deposit, judging from their surface morphologic expression on the sea floor, extending at least 15 km and possibly as much as 30 km from the volcano, into the Grenada Basin to the west. Seismic air-gun profiles of the region show that these are lobate deposits, that range in thickness from tens to hundreds of meters. The debris avalanche deposit is contained within two marginal levees, that extend symmetrically from the volcano to the west. A conservative estimate of the volume of the smaller debris avalanche deposit is about 10 km3. Age dating of the deposits and the flank failure events is in progress, by analysis of gravity cores collected during the 2003 survey. Reconstruction of the pre-collapse volcanic edifice suggests that the ancestral Kick'em Jenny volcano might have been at or above sea level. Kick'em Jenny is dominantly supplied by basalt to basaltic andesite magmas, that are extruded now as submarine pillow lavas and domes or ejected as tephra in relatively minor phreatomagmatic explosions. Geochemical evolution of this volcano has not, however, reached the stage of generation of volatile-rich silicic magmas that might form highly explosive eruptions.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Discovery of an active shallow submarine silicic volcano in the northern Izu-Bonin Arc: volcanic structure and potential hazards of Oomurodashi Volcano (Invited)

    NASA Astrophysics Data System (ADS)

    Tani, K.; Ishizuka, O.; Nichols, A. R.; Hirahara, Y.; Carey, R.; McIntosh, I. M.; Masaki, Y.; Kondo, R.; Miyairi, Y.

    2013-12-01

    Oomurodashi is a bathymetric high located ~20 km south of Izu-Oshima, an active volcanic island of the northern Izu-Bonin Arc. Using the 200 m bathymetric contour to define its summit dimensions, the diameter of Oomurodashi is ~20 km. Oomurodashi has been regarded as inactive, largely because it has a vast flat-topped summit at 100 - 150 meters below sea level (mbsl). During cruise NT07-15 of R/V Natsushima in 2007, we conducted a dive survey in a small crater, Oomuro Hole, located in the center of the flat-topped summit, using the remotely-operated vehicle (ROV) Hyper-Dolphin. The only heat flow measurement conducted on the floor of Oomuro Hole during the dive recorded an extremely high value of 4,200 mW/m2. Furthermore, ROV observations revealed that the southwestern wall of Oomuro Hole consists of fresh rhyolitic lavas. These findings suggest that Oomurodashi is in fact an active silicic submarine volcano. To confirm this hypothesis, we conducted detailed geological and geophysical ROV Hyper-Dolphin (cruise NT12-19). In addition to further ROV surveys, we carried out single-channel seismic (SCS) surveys across Oomurodashi in order to examine the shallow structures beneath the current edifice. The ROV surveys revealed numerous active hydrothermal vents on the floor of Oomuro Hole, at ~200 mbsl, with maximum water temperature measured at the hydrothermal vents reaching 194°C. We also conducted a much more detailed set of heat flow measurements across the floor of Oomuro Hole, detecting very high heat flows of up to 29,000 mW/m2. ROV observations revealed that the area surrounding Oomuro Hole on the flat-topped summit of Oomurodashi is covered by extensive fresh rhyolitic lava and pumice clasts with minimum biogenetic or manganese cover, suggesting recent eruption(s). These findings strongly indicate that Oomurodashi is an active silicic submarine volcano, with recent eruption(s) occurring from Oomuro Hole. Since the summit of Oomurodashi is in shallow water, it

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

    NASA Astrophysics Data System (ADS)

    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

  3. Integrated volcanologic and petrologic analysis of the 1650 AD eruption of Kolumbo submarine volcano, Greece

    NASA Astrophysics Data System (ADS)

    Cantner, Kathleen; Carey, Steven; Nomikou, Paraskevi

    2014-01-01

    Kolumbo submarine volcano, located 7 km northeast of Santorini, Greece in the Aegean Sea, last erupted in 1650 AD. Submarine and subaerial explosive activity lasted for a period of about four months and led to the formation of thick (~ 250 m) highly stratified pumice deposits on the upper crater walls as well as extensive pumice rafts that were dispersed throughout the southern Aegean Sea. Subaerial tephra fallout from eruption columns that breached the surface occurred as far east as Turkey.

  4. Submarine radial vents on Mauna Loa Volcano, Hawai'i

    USGS Publications Warehouse

    Wanless, V. Dorsey; Garcia, M.O.; Trusdell, F.A.; Rhodes, J.M.; Norman, M.D.; Weis, Dominique; Fornari, D.J.; Kurz, M.D.; Guillou, Herve

    2006-01-01

    A 2002 multibeam sonar survey of Mauna Loa's western flank revealed ten submarine radial vents and three submarine lava flows. Only one submarine radial vent was known previously. The ages of these vents are constrained by eyewitness accounts, geologic relationships, Mn-Fe coatings, and geochemical stratigraphy; they range from 128 years B.P. to possibly 47 ka. Eight of the radial vents produced degassed lavas despite eruption in water depths sufficient to inhibit sulfur degassing. These vents formed truncated cones and short lava flows. Two vents produced undegassed lavas that created “irregular” cones and longer lava flows. Compositionally and isotopically, the submarine radial vent lavas are typical of Mauna Loa lavas, except two cones that erupted alkalic lavas. He-Sr isotopes for the radial vent lavas follow Mauna Loa's evolutionary trend. The compositional and isotopic heterogeneity of these lavas indicates most had distinct parental magmas. Bathymetry and acoustic backscatter results, along with photography and sampling during four JASON2 dives, are used to produce a detailed geologic map to evaluate Mauna Loa's submarine geologic history. The new map shows that the 1877 submarine eruption was much larger than previously thought, resulting in a 10% increase for recent volcanism. Furthermore, although alkalic lavas were found at two radial vents, there is no systematic increase in alkalinity among these or other Mauna Loa lavas as expected for a dying volcano. These results refute an interpretation that Mauna Loa's volcanism is waning. The submarine radial vents and flows cover 29 km2 of seafloor and comprise a total volume of ∼2×109 m3 of lava, reinforcing the idea that submarine lava eruptions are important in the growth of oceanic island volcanoes even after they emerged above sea level.

  5. Products of Submarine Fountains and Bubble-burst Eruptive Activity at 1200 m on West Mata Volcano, Lau Basin

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Rubin, K. H.; Keller, N. S.

    2009-12-01

    An eruption was observed and sampled at West Mata Volcano using ROV JASON II for 5 days in May 2009 during the NSF-NOAA eruption response cruise to this region of suspected volcanic activity. Activity was focused near the summit at the Prometheus and Hades vents. Prometheus erupted almost exclusively as low-level fountains. Activity at Hades cycled between vigorous degassing, low fountains, and bubble-bursts, building up and partially collapsing a small spatter/scoria cone and feeding short sheet-like and pillow flows. Fire fountains at Prometheus produced mostly small primary pyroclasts that include Pele's hair and fluidal fragments of highly vesicular volcanic glass. These fragments have mostly shattered and broken surfaces, although smooth spatter-like surfaces also occur. As activity wanes, glow in the vent fades, and denser, sometimes altered volcanic clasts are incorporated into the eruption. The latter are likely from the conduit walls and/or vent-rim ejecta, drawn back into the vent by inrushing seawater that replaces water entrained in the rising volcanic plume. Repeated recycling of previously erupted materials eventually produces rounded clasts resembling beach cobbles and pitted surfaces on broken phenocrysts of pyroxene and olivine. We estimate that roughly 33% of near vent ejecta are recycled. Our best sample of this ejecta type was deposited in the drawer of the JASON II ROV during a particularly large explosion that occurred during plume sampling immediately above the vent. Elemental sulfur spherules up to 5 mm in diameter are common in ejecta from both vents and occur inside some of the lava fragments Hades activity included dramatic bubble-bursts unlike anything previously observed under water. The lava bubbles, sometimes occurring in rapid-fire sequence, collapsed in the water-column, producing fragments that are quenched in less than a second to form Pele's hair, limu o Pele, spatter-like lava blobs, and scoria. All are highly vesicular

  6. Updated bathymetric survey of Kick-'em-Jenny submarine volcano

    NASA Astrophysics Data System (ADS)

    Watlington, R. A.; Wilson, W. D.; Johns, W. E.; Nelson, C.

    High-resolution bathymetric data obtained in July 1996 during a survey of the Kick-'em-Jenny submarine volcano north of Grenada in the Lesser Antilles revealed changes in the structure of the volcanic edifice compared to previously available surveys. The volcano's summit, at 178 m below sea level, was found to be approximately 18 m farther from the surface than was reported by Bouysse et al. (1988) and others. No dome was observed. Instead, an open crater, surrounded by walls that dropped significantly in elevation from one side to the opposite, suggest that eruptions, earthquakes, rockfalls or explosions may have altered the structure since the last detailed survey. The deepest contour of the volcano's crater was found 106 m below the summit.

  7. Active Submarine Volcanoes and Electro-Optical Sensor Networks: The Potential of Capturing and Quantifying an Entire Eruptive Sequence at Axial Seamount, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Delaney, J. R.; Kelley, D. S.; Proskurowski, G.; Fundis, A. T.; Kawka, O.

    2011-12-01

    The NE Pacific Regional Scale Nodes (RSN) component of the NSF Ocean Observatories Initiative is designed to provide unprecedented electrical power and bandwidth to the base and summit of Axial Seamount. The scientific community is engaged in identifying a host of existing and innovative observation and measurement techniques that utilize the high-power and bandwidth infrastructure and its real-time transmission capabilities. The cable, mooring, and sensor arrays will enable the first quantitative documentation of myriad processes leading up to, during, and following a submarine volcanic event. Currently planned RSN instrument arrays will provide important and concurrent spatial and temporal constraints on earthquake activity, melt migration, hydrothermal venting behavior and chemistry, ambient currents, microbial community structure, high-definition (HD) still images and HD video streaming from the vents, and water-column chemistry in the overlying ocean. Anticipated, but not yet funded, additions will include AUVs and gliders that continually document the spatial-temporal variations in the water column above the volcano and the distal zones. When an eruption appears imminent the frequency of sampling will be increased remotely, and the potential of repurposing the tracking capabilities of the mobile sensing platforms will be adapted to the spatial indicators of likely eruption activity. As the eruption begins mobile platforms will fully define the geometry, temperature, and chemical-microbial character of the volcanic plume as it rises into the thoroughly documented control volume above the volcano. Via the Internet the scientific community will be able to witness and direct adaptive sampling in response to changing conditions of plume formation. A major goal will be to document the eruptive volume and link the eruption duration to the volume of erupted magma. For the first time, it will be possible to begin to quantify the time-integrated output of an underwater

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Near-specular acoustic scattering from a buried submarine mud volcano.

    PubMed

    Gerig, Anthony L; Holland, Charles W

    2007-12-01

    Submarine mud volcanoes are objects that form on the seafloor due to the emission of gas and fluidized sediment from the Earth's interior. They vary widely in size, can be exposed or buried, and are of interest to the underwater acoustics community as potential sources of active sonar clutter. Coincident seismic reflection data and low frequency bistatic scattering data were gathered from one such buried mud volcano located in the Straits of Sicily. The bistatic data were generated using a pulsed piston source and a 64-element horizontal array, both towed over the top of the volcano. The purpose of this work was to appropriately model low frequency scattering from the volcano using the bistatic returns, seismic bathymetry, and knowledge of the general geoacoustic properties of the area's seabed to guide understanding and model development. Ray theory, with some approximations, was used to model acoustic propagation through overlying layers. Due to the volcano's size, scattering was modeled using geometric acoustics and a simple representation of volcano shape. Modeled bistatic data compared relatively well with experimental data, although some features remain unexplained. Results of an inversion for the volcano's reflection coefficient indicate that it may be acoustically softer than expected.

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

    NASA Astrophysics Data System (ADS)

    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

  12. Sector collapse at Kick 'em Jenny submarine volcano (Lesser Antilles): numerical simulation and landslide behaviour

    NASA Astrophysics Data System (ADS)

    Dondin, Frédéric; Lebrun, Jean-Frédéric; Kelfoun, Karim; Fournier, Nicolas; Randrianasolo, Auran

    2012-03-01

    Kick 'em Jenny volcano is the only known active submarine volcano in the Lesser Antilles. It lies within a horseshoe-shaped structure open to the west northwest, toward the deep Grenada Basin. A detailed bathymetric survey of the basin slope at Kick 'em Jenny and resulting high-resolution digital elevation model allowed the identification of a major submarine landslide deposit. This deposit is thought to result from a single sector collapse event at Kick 'em Jenny and to be linked to the formation of the horseshoe-shaped structure. We estimated the volume and the leading-edge runout of the landslide to be ca. 4.4 km3 and 14 km, respectively. We modelled a sector collapse event of a proto Kick 'em Jenny volcano using VolcFlow, a finite difference code based on depth-integrated mass and momentum equations. Our models show that the landslide can be simulated by either a Coulomb-type rheology with low basal friction angles (5.5°-6.5°) and a significant internal friction angle (above 17.5°) or, with better results, by a Bingham rheology with low Bingham kinematic viscosity (0 < ν B < 30 m2/s) and high shear strength (130 < γ ≤ 180 m2/s2). The models and the short runout distance suggest that the landslide travelled as a stiff cohesive flow affected by minimal granular disaggregation and slumping on a non-lubricated surface. The main submarine landslide deposit can therefore be considered as a submarine mass slide deposit that behaved like a slump.

  13. A Miocene submarine volcano at Low Layton, Jamaica

    NASA Technical Reports Server (NTRS)

    Wadge, G.

    1982-01-01

    A submarine fissure eruption of Upper Miocene age produced a modest volume of alkaline basalt at Low Layton, on the north coast of Jamaica. The eruption occurred in no more than a few hundred meters of water and produced a series of hyaloclastites, pillow breccias and pillow lavas, massive lavas, and dikes with an ENE en echelon structure. The volcano lies on the trend of one of the island's major E-W strike-slip fault zones; the Dunavale Fault Zone. The K-Ar age of the eruption of 9.5 plus or minus 0.5 Ma. B.P. corresponds to an extension of the Mid-Cayman Rise spreading center inferred from magnetic anomalies and bathymetry of the Cayman Trough to the north and west of Jamaica. The Low Layton eruption was part of the response of the strike-slip fault systems adjacent to this spreading center during this brief episode of tectonic readjustment.

  14. The 2014 Submarine Eruption of Ahyi Volcano, Northern Mariana Islands

    NASA Astrophysics Data System (ADS)

    Haney, M. M.; Chadwick, W.; Merle, S. G.; Buck, N. J.; Butterfield, D. A.; Coombs, M. L.; Evers, L. G.; Heaney, K. D.; Lyons, J. J.; Searcy, C. K.; Walker, S. L.; Young, C.; Embley, R. W.

    2014-12-01

    On April 23, 2014, Ahyi Volcano, a submarine cone in the Northern Mariana Islands (NMI), ended a 13-year-long period of repose with an explosive eruption lasting over 2 weeks. The remoteness of the volcano and the presence of several seamounts in the immediate area posed a challenge for constraining the source location of the eruption. Critical to honing in on the Ahyi area quickly were quantitative error estimates provided by the CTBTO on the backazimuth of hydroacoustic arrivals observed at Wake Island (IMS station H11). T-phases registered across the NMI seismic network at the rate of approximately 10 per hour until May 8 and were observed in hindsight at seismic stations on Guam and Chichijima. After May 8, sporadic T-phases were observed until May 17. Within days of the eruption onset, reports were received from NOAA research divers of hearing explosions underwater and through the hull on the ship while working on the SE coastline of Farallon de Pajaros (Uracas), a distance of 20 km NW of Ahyi. In the same area, the NOAA crew reported sighting mats of orange-yellow bubbles on the water surface and extending up to 1 km from the shoreline. Despite these observations, satellite images showed nothing unusual throughout the eruption. During mid-May, a later cruise leg on the NOAA ship Hi'ialakai that was previously scheduled in the Ahyi area was able to collect some additional data in response to the eruption. Preliminary multibeam sonar bathymetry and water-column CTD casts were obtained at Ahyi. Comparison between 2003 and 2014 bathymetry revealed that the minimum depth had changed from 60 m in 2003 to 75 m in 2014, and a new crater ~95 m deep had formed at the summit. Extending SSE from the crater was a new scoured-out landslide chute extending downslope to a depth of at least 2300 m. Up to 125 m of material had been removed from the head of the landslide chute and downslope deposits were up to 40 m thick. Significant particle plumes were detected at all three

  15. The submarine flanks of Anatahan Volcano, commonwealth of the Northern Mariana Islands

    NASA Astrophysics Data System (ADS)

    Chadwick, William W.; Embley, Robert W.; Johnson, Paul D.; Merle, Susan G.; Ristau, Shannon; Bobbitt, Andra

    2005-08-01

    The submarine flanks of Anatahan volcano were surveyed comprehensively for the first time in 2003 and 2004 with multibeam and sidescan sonar systems. A geologic map based on the new bathymetry and backscatter data shows that 67% of the volcano's submarine flanks are covered with volcaniclastic debris and 26% is lava flows, cones, and bedrock outcrops. The island of Anatahan is only 1% of the volume of the entire volcano, which has a height from its submarine base of 3700 m and an average diameter of ˜35 km. NE Anatahan is a prominent satellite volcano located 10 km NE of the island, but it is only 6% of Anatahan's volume (40 km 3 vs. 620 km 3). Seventy-eight submarine eruptive vents are mapped associated with lava flows and cones between depths of 350 and 2950 m, and 80% of these vents are located in a cluster on the east flank of the volcano. The distribution of cones and lava flows vs. depth suggests a possible change in eruptive style from explosive to effusive between 1500 and 2000 m. Eruptive vents below 2000 m have produced mostly lava flows. There is no evidence of major landslides on the submarine flanks of Anatahan volcano, in contrast to many basaltic islands and seamounts, suggesting that mass wasting at felsic oceanic arc volcanoes may be characterized by sediment flows of unconsolidated volcaniclastic debris instead of mass movements of relatively large intact blocks.

  16. H2O Contents of Submarine and Subaerial Silicic Pyroclasts from Oomurodashi Volcano, Northern Izu-Bonin Arc

    NASA Astrophysics Data System (ADS)

    McIntosh, I. M.; Tani, K.; Nichols, A. R.

    2014-12-01

    Oomurodashi volcano is an active shallow submarine silicic volcano in the northern Izu-Bonin Arc, located ~20 km south of the inhabited active volcanic island of Izu-Oshima. Oomurodashi has a large (~20km diameter) flat-topped summit located at 100 - 150 metres below sea level (mbsl), with a small central crater, Oomuro Hole, located at ~200 mbsl. Surveys conducted during cruise NT12-19 of R/V Natsushima in 2012 using the remotely-operated vehicle (ROV) Hyper-Dolphin revealed that Oomuro Hole contains numerous active hydrothermal vents and that the summit of Oomurodashi is covered by extensive fresh rhyolitic lava and pumice clasts with little biogenetic or manganese cover, suggesting recent eruption(s) from Oomuro Hole. Given the shallow depth of the volcano summit, such eruptions are likely to have generated subaerial eruption columns. A ~10ka pumiceous subaerial tephra layer on the neighbouring island of Izu-Oshima has a similar chemical composition to the submarine Oomurodashi rocks collected during the NT12-19 cruise and is thought to have originated from Oomurodashi. Here we present FTIR measurements of the H2O contents of rhyolitic pumice from both the submarine deposits sampled during ROV dives and the subaerial tephra deposit on Izu-Oshima, in order to assess magma degassing and eruption processes occurring during shallow submarine eruptions.

  17. Preliminary results from Submarine Ring of Fire 2012 - NE Lau: First explorations of hydrothermally active volcanoes across the supra-subduction zone and a return to the West Mata eruption site

    NASA Astrophysics Data System (ADS)

    Resing, J.; Embley, R. W.

    2012-12-01

    Several expeditions in the past few years have shown that the NE Lau basin has one of the densest concentrations of volcanically and hydrothermally active volcanoes on the planet. In 2008 two active submarine volcanic eruptions were discovered during a one week period and subsequent dives with the Jason remotely operated vehicle at one of the sites (West Mata) revealed an active boninite eruption taking place at 1200 m depth. Two dives at the other revealed evidence for recent eruption along the NE Lau Spreading Center. Several more expeditions in 2010-11 discovered additional evidence about the extent and types of hydrothermal activity in this area. Data from CTDO (conductivity, temperature, depth, optical) vertical casts, tow-yos, and towed camera deployments revealed more than 15 hydrothermal sites at water depths from ~800 to 2700 m that include sites from the magmatic arc, the "rear arc," and the back arc spreading centers. These sites range from high temperature black smoker sulfide-producing systems to those dominated by magmatic degassing. Dives by remotely operated vehicle (Quest 4000) in September 2012 will explore these sites and return samples for chemical, biological and geologic studies. One of the dives will be a return visit to West Mata volcano, the site of the deepest submarine eruption yet observed (in 2009). Recent multibeam data reveal large changes in West Mata's summit, suggesting that the nature of the eruption and the location of the erupting vents may have changed. In addition to the preliminary results from the science team, we will also discuss our use and experience with continuous live video transmission (through the High Definition video camera on the Quest 4000) back to shore via satellite and through the internet. Submarine Ring of Fire 2012 Science Team: Bradley Tebo, Bill Chadwick, Ed Baker, Ken Rubin, Susan Merle, Timothy Shank, Sharon Walker, Andra Bobbitt, Nathan Buck, David Butterfield, Eric Olson, John Lupton, Richard Arculus

  18. Are midwater shrimp trapped in the craters of submarine volcanoes by hydrothermal venting?

    NASA Astrophysics Data System (ADS)

    Wishner, Karen F.; Graff, Jason R.; Martin, Joel W.; Carey, S.; Sigurdsson, H.; Seibel, B. A.

    2005-08-01

    The biology of Kick'em Jenny (KEJ) submarine volcano, part of the Lesser Antilles volcanic arc and located off the coast of Grenada in the Caribbean Sea, was studied during a cruise in 2003. Hydrothermal venting and an associated biological assemblage were discovered in the volcanic crater (˜250 m depth). Warm water with bubbling gas emanated through rock fissures and sediments. Shrimp (some of them swimming) were clustered at vents, while other individuals lay immobile on sediments. The shrimp fauna consisted of 3 mesopelagic species that had no prior record of benthic or vent association. We suggest that these midwater shrimp, from deeper water populations offshore, were trapped within the crater during their downward diel vertical migration. It is unknown whether they then succumbed to the hostile vent environment (immobile individuals) or whether they are potentially opportunistic vent residents (active individuals). Given the abundance of submarine arc volcanoes worldwide, this phenomenon suggests that volcanic arcs could be important interaction sites between oceanic midwater and vent communities.

  19. Submarine geology of the Hilina slump and morpho-structural evolution of Kilauea volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Smith, John R.; Malahoff, Alexander; Shor, Alexander N.

    1999-12-01

    Marine geophysical data, including SEA BEAM bathymetry, HAWAII MR1 sidescan, and seismic reflection profiles, along with recent robot submersible observations and samples, were acquired over the offshore continuation of the mobile Kilauea volcano south flank. This slope comprises the three active hot spot volcanoes Mauna Loa, Kilauea, and Loihi seamount and is the locus of the Hawaiian hot spot. The south flank is the site of frequent low-intensity seismicity as well as episodic large-magnitude earthquakes. Its sub-aerial portion creeps seaward at a rate of approximately 10 cm/year. The Hilina slump is the only large submarine landslide in the Hawaiian Archipelago thought to be active, and this study is one of the first to more highly resolve submarine slide features there. The slump is classified into four distinct zones from nearshore to the island's base. Estimates of size based on these data indicate a slumped area of 2100 km 2 and a volume of 10,000-12,000 km 3, equivalent to about 10% of the entire island edifice. The overall picture gained from these data sets is one of mass wasting of the neovolcanic terrain as it builds upward and seaward, though reinforcement by young and pre-Hawaii seamounts adjacent to the pedestal is apparent. Extensive lava delta deposits are formed by hyaloclastites and detritus from recent lava flows into the sea. These deposits dominate the upper submarine slope offshore of Kilauea, with pillow breccia revealed at mid-depths. Along the lower flanks, massive outcrops of volcanically derived sedimentary rocks were found underlying Kilauea, thus necessitating a rethinking of previous models of volcanic island development. The morphologic and structural evolutionary model for Kilauea volcano and the Hilina slump proposed here attempts to incorporate this revelation. A hazard assessment for the Hilina slump is presented where it is suggested that displacement of the south flank to date has been restrained by a still developing northeast

  20. Distribution of tephra from the 1650 AD submarine eruption of Kolumbo volcano, Greece

    NASA Astrophysics Data System (ADS)

    Fuller, S. A.; Carey, S.; Nomikou, P.

    2013-12-01

    Kolumbo submarine volcano, located 7 km northeast of Santorini in the Aegean Sea, last erupted in 1650 AD resulting in about 70 fatalities on Thera from gas discharge and significant coastal destruction from tsunamis. Extensive pumice rafts were reported over a large area surrounding Santorini, extending as far south as Crete. Tephra from the 1650 AD submarine eruption has been correlated in sediment box cores using a combination of mineralogy and major element composition of glass shards. The biotite-bearing rhyolite of Kolumbo can be readily discriminated from other silicic pyroclastics derived from the main Santorini complex. In general the tephra deposits are very fine grained (silt to fine sand-size), medium gray in color, and covered by about 10 cms of brown hemipelagic sediment. This corresponds to an average background sedimentation rate of 29 cm/kyr. The distribution of the 1650 AD Kolumbo tephra extends over an area larger than previously inferred from seismic profiles on the volcano's slopes and in adjacent basins. The cores indicate tephra deposits at least 19 km from the caldera, more than double the approximate 9 km inferred from seismic data. The preferential occurrence of the tephra within basins and sedimentological features such as cross bedding and laminations suggests that emplacement was dominated by sediment gravity flows generated from submarine and subaerial eruption plumes. We suggest that generation of the sediment gravity flows took place by collapse of submarine eruption columns and by Rayleigh-Taylor instabilities that formed on the sea surface as subaerial fallout accumulated from parts of the columns that breached the surface. Additionally, SEM imaging reveals particle morphologies that can be attributed to fragmentation by both primary volatile degassing (bubble wall shards) and phreatomagmatic activity (blocky equant grains). It is likely that phreatomagmatic activity became more important in the latter stages of the eruptive

  1. Imaging of CO2 bubble plumes above an erupting submarine volcano, NW Rota-1, Mariana Arc

    NASA Astrophysics Data System (ADS)

    Chadwick, William W.; Merle, Susan G.; Buck, Nathaniel J.; Lavelle, J. William; Resing, Joseph A.; Ferrini, Vicki

    2014-11-01

    Rota-1 is a submarine volcano in the Mariana volcanic arc located ˜100 km north of Guam. Underwater explosive eruptions driven by magmatic gases were first witnessed there in 2004 and continued until at least 2010. During a March 2010 expedition, visual observations documented continuous but variable eruptive activity at multiple vents at ˜560 m depth. Some vents released CO2 bubbles passively and continuously, while others released CO2 during stronger but intermittent explosive bursts. Plumes of CO2 bubbles in the water column over the volcano were imaged by an EM122 (12 kHz) multibeam sonar system. Throughout the 2010 expedition numerous passes were made over the eruptive vents with the ship to document the temporal variability of the bubble plumes and relate them to the eruptive activity on the seafloor, as recorded by an in situ hydrophone and visual observations. Analysis of the EM122 midwater data set shows: (1) bubble plumes were present on every pass over the summit and they rose 200-400 m above the vents but dissolved before they reached the ocean surface, (2) bubble plume deflection direction and distance correlate well with ocean current direction and velocity determined from the ship's acoustic doppler current profiler, (3) bubble plume heights and volumes were variable over time and correlate with eruptive intensity as measured by the in situ hydrophone. This study shows that midwater multibeam sonar data can be used to characterize the level of eruptive activity and its temporal variability at a shallow submarine volcano with robust CO2 output.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    In 2009 the first marine protected areas for deep-sea hydrothermal vents in U.S. waters were established as part of the Volcanic Unit of the Marianas Trench Marine National Monument. In this region, hydrothermal vents are located along the Mariana Arc and back-arc spreading center. In particular hydrothermal vents are located near the summit of NW Rota-1, an active submarine volcano on the Mariana Arc which was erupting between 2003 through 2010 and ceased as of 2014. In late 2009, NW Rota-1 experienced a massive landslide decimating the habitat on the southern side of the volcano. This presented an enormous natural disturbance to the community. This project looked at zooplankton tow samples taken from the water column above NW Rota-1 in 2010, searching specifically for larvae which have the potential to recolonize the sea floor after such a major disturbance. We focused on samples for which profiles with a MAPR sensor indicated hydrothermal plumes in the water column. Samples were sorted in entirety into coarse taxa, and then larvae were removed for DNA barcoding. Overall zooplankton composition was dominated by copepods, ostracods, and chaetognaths, the majority of which are pelagic organisms. Comparatively few larvae of benthic invertebrates were found, but shrimp, gastropod, barnacle, and polychaete larvae did appear in low numbers in the samples. Species-level identification obtained via genetic barcoding will allow for these larvae to be matched to species known to inhabit the benthic communities at NW Rota-1. Identified larvae will give insight into the organisms which can re-colonize the seafloor vent communities after a disturbance such as the 2009 landslide. Communities at hydrothermal vents at other submarine volcanoes in the Monument also can act as sources for these planktonic, recolonizing larvae. As the microinvertebrate biodiversity in the Monument has yet to be fully characterized, our project also provides an opportunity to better describe both

  3. Bubble Plumes above erupting NW Rota-1 submarine volcano, Mariana Arc

    NASA Astrophysics Data System (ADS)

    Chadwick, B.; Merle, S. G.; Embley, R. W.; Buck, N.; Resing, J. A.; Leifer, I.

    2013-12-01

    NW Rota-1 is a submarine volcano in the Mariana volcanic arc with a summit depth of 517 m, located ~100 km north of Guam. Underwater explosive eruptions driven by magmatic gases were first witnessed here in 2004 and the volcano has remained persistently active ever since. During a March 2010 expedition to NW Rota-1 with the remotely operated vehicle Jason, we observed intermittent explosive activity at five distinct eruptive vents along a line 100-m long near the summit of the volcano (550-590 m depth). The continuous but variable eruptive activity produced CO2 bubble plumes that rose in the water column over the volcano and could be readily imaged by sonar because they provide excellent acoustic reflectors. This study compares the manifestations of NW Rota's eruptive activity as measured by several independent methods, including: (1) an EM122 multibeam sonar system (12 kHz) on the R/V Kilo Moana that imaged bubble plumes in the water column over the volcano, (2) hydrophone data that recorded the sounds of the variable eruptive activity, and (3) visual observations of the activity at the eruptive vents on the seafloor from Jason. Throughout the 2010 expedition numerous passes were made over the volcano's summit to image the bubble plumes with the EM122 multibeam sonar, in order to capture the variability of the plumes over time and to relate them to the eruptive output of the volcano. The mid-water sonar dataset totals >95 hours of observations over a 12-day period. Analysis of the EM122 dataset shows: (1) bubble plumes were visible in the water column on every pass over the summit, (2) separate plumes were resolvable from up to 4 of the 5 eruptive vents at times, (3) plume heights and intensities were variable with time, (4) the highest observed bubble plume rise height was 415 meters above the seafloor to within 175 m of the ocean surface, while lower amplitude wisps rose to heights <100 m from the surface, (5) most of the bubble plumes were deflected to the WSW

  4. Numerical tsunami hazard assessment of the submarine volcano Kick 'em Jenny in high resolution are

    NASA Astrophysics Data System (ADS)

    Dondin, Frédéric; Dorville, Jean-Francois Marc; Robertson, Richard E. A.

    2016-04-01

    Landslide-generated tsunami are infrequent phenomena that can be potentially highly hazardous for population located in the near-field domain of the source. The Lesser Antilles volcanic arc is a curved 800 km chain of volcanic islands. At least 53 flank collapse episodes have been recognized along the arc. Several of these collapses have been associated with underwater voluminous deposits (volume > 1 km3). Due to their momentum these events were likely capable of generating regional tsunami. However no clear field evidence of tsunami associated with these voluminous events have been reported but the occurrence of such an episode nowadays would certainly have catastrophic consequences. Kick 'em Jenny (KeJ) is the only active submarine volcano of the Lesser Antilles Arc (LAA), with a current edifice volume estimated to 1.5 km3. It is the southernmost edifice of the LAA with recognized associated volcanic landslide deposits. The volcano appears to have undergone three episodes of flank failure. Numerical simulations of one of these episodes associated with a collapse volume of ca. 4.4 km3 and considering a single pulse collapse revealed that this episode would have produced a regional tsunami with amplitude of 30 m. In the present study we applied a detailed hazard assessment on KeJ submarine volcano (KeJ) form its collapse to its waves impact on high resolution coastal area of selected island of the LAA in order to highlight needs to improve alert system and risk mitigation. We present the assessment process of tsunami hazard related to shoreline surface elevation (i.e. run-up) and flood dynamic (i.e. duration, height, speed...) at the coast of LAA island in the case of a potential flank collapse scenario at KeJ. After quantification of potential initial volumes of collapse material using relative slope instability analysis (RSIA, VolcanoFit 2.0 & SSAP 4.5) based on seven geomechanical models, the tsunami source have been simulate by St-Venant equations-based code

  5. North Kona slump: Submarine flank failure during the early(?) tholeiitic shield stage of Hualalai Volcano

    USGS Publications Warehouse

    Lipman, P.W.; Coombs, M.L.

    2006-01-01

    The North Kona slump is an elliptical region, about 20 by 60 km (1000-km2 area), of multiple, geometrically intricate benches and scarps, mostly at water depths of 2000–4500 m, on the west flank of Hualalai Volcano. Two dives up steep scarps in the slump area were made in September 2001, using the ROV Kaiko of the Japan Marine Science and Technology Center (JAMSTEC), as part of a collaborative Japan–USA project to improve understanding of the submarine flanks of Hawaiian volcanoes. Both dives, at water depths of 2700–4000 m, encountered pillow lavas draping the scarp-and-bench slopes. Intact to only slightly broken pillow lobes and cylinders that are downward elongate dominate on the steepest mid-sections of scarps, while more equant and spherical pillow shapes are common near the tops and bases of scarps and locally protrude through cover of muddy sediment on bench flats. Notably absent are subaerially erupted Hualalai lava flows, interbedded hyaloclastite pillow breccia, and/or coastal sandy sediment that might have accumulated downslope from an active coastline. The general structure of the North Kona flank is interpreted as an intricate assemblage of downdropped lenticular blocks, bounded by steeply dipping normal faults. The undisturbed pillow-lava drape indicates that slumping occurred during shield-stage tholeiitic volcanism. All analyzed samples of the pillow-lava drape are tholeiite, similar to published analyses from the submarine northwest rift zone of Hualālai. Relatively low sulfur (330–600 ppm) and water (0.18–0.47 wt.%) contents of glass rinds suggest that the eruptive sources were in shallow water, perhaps 500–1000-m depth. In contrast, saturation pressures calculated from carbon dioxide concentrations (100–190 ppm) indicate deeper equilibration, at or near sample sites at water depths of − 3900 to − 2800 m. Either vents close to the sample sites erupted mixtures of undegassed and degassed magmas, or volatiles were resorbed from

  6. Submarine lavas from Mauna Kea Volcano, Hawaii: Implications for Hawaiian shield stage processes

    NASA Astrophysics Data System (ADS)

    Yang, Huai-Jen; Frey, Frederick A.; Garcia, Michael O.; Clague, David A.

    1994-08-01

    The island of Hawaii is composed of five voluminous shields but only the youngest, active and well-exposed shields of Mauna Loa and Kilauea have been studied in detail. The shield lavas forming Kohala, Hualalai, and Mauna Kea are largely covered by postshield lavas with geochemical characteristics that differ from the shield lavas. In order to determine the geochemical characteristics of the Mauna Kea shield which is adjacent to the Kilauea and Mauna Loa shields, 12 Mauna Kea shield basalts dredged from the submarine east rift were analyzed for major and trace element contents and isotopic (Sr, Nd, and Pb) ratios. The lavas are MgO-rich (11 to 20%), submarine erupted, tholeiitic basalts, but they are not representative of crystallized MgO-rich melts. Their whole rock and mineral compositions are consistent with mixing of an evolved magma, less than 7% MgO, with a magma containing abundant olivine xenocrysts, probably disaggregated from a dunitic cumulate. At a given MgO content, some of the Mauna Kea whole rocks have lower abundances of CaO and higher abundances of incompatible elements. The evolved melt component in these lavas reflects significant fractionation of plagioclase and clinopyroxene and in some cases even the late crystallizing phases orthopyroxene and Fe-Ti oxide. Although these Mauna Kea lavas are not isotopically homogenous, in general their Sr, Nd, and Pb isotopic ratios overlap with the fields for lavas from Loihi and Kilauea volcanoes.

  7. Submarine radial vents on Mauna Loa Volcano, Hawaìi

    NASA Astrophysics Data System (ADS)

    Wanless, V. Dorsey; Garcia, M. O.; Trusdell, F. A.; Rhodes, J. M.; Norman, M. D.; Weis, Dominique; Fornari, D. J.; Kurz, M. D.; Guillou, Hervé

    2006-05-01

    A 2002 multibeam sonar survey of Mauna Loa's western flank revealed ten submarine radial vents and three submarine lava flows. Only one submarine radial vent was known previously. The ages of these vents are constrained by eyewitness accounts, geologic relationships, Mn-Fe coatings, and geochemical stratigraphy; they range from 128 years B.P. to possibly 47 ka. Eight of the radial vents produced degassed lavas despite eruption in water depths sufficient to inhibit sulfur degassing. These vents formed truncated cones and short lava flows. Two vents produced undegassed lavas that created "irregular" cones and longer lava flows. Compositionally and isotopically, the submarine radial vent lavas are typical of Mauna Loa lavas, except two cones that erupted alkalic lavas. He-Sr isotopes for the radial vent lavas follow Mauna Loa's evolutionary trend. The compositional and isotopic heterogeneity of these lavas indicates most had distinct parental magmas. Bathymetry and acoustic backscatter results, along with photography and sampling during four JASON2 dives, are used to produce a detailed geologic map to evaluate Mauna Loa's submarine geologic history. The new map shows that the 1877 submarine eruption was much larger than previously thought, resulting in a 10% increase for recent volcanism. Furthermore, although alkalic lavas were found at two radial vents, there is no systematic increase in alkalinity among these or other Mauna Loa lavas as expected for a dying volcano. These results refute an interpretation that Mauna Loa's volcanism is waning. The submarine radial vents and flows cover 29 km2 of seafloor and comprise a total volume of ˜2 × 109 m3 of lava, reinforcing the idea that submarine lava eruptions are important in the growth of oceanic island volcanoes even after they emerged above sea level.

  8. Argon-40: excess in submarine pillow basalts from kilauea volcano, hawaii.

    PubMed

    Dalrymple, G B; Moore, J G

    1968-09-13

    Submarine pillow basalts from Kilauea Volcano contain excess radiogenic argon-40 and give anomalously high potassium-argon ages. Glassy rims of pillows show a systematic increase in radiogenic argon-40 with depth, and a pillow from a depth of 2590 meters shows a decrease in radiogenic argon40 inward from the pillow rim. The data indicate that the amount of excess radiogenic argon-40 is a direct function of both hydrostatic pressure and rate of cooling, and that many submarine basalts are not suitable for potassium-argon dating.

  9. Underwater observations of active lava flows from Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Tribble, G.W.

    1991-01-01

    Underwater observation of active submarine lava flows from Kilauea volcano, Hawaii, in March-June 1989 revealed both pillow lava and highly channelized lava streams flowing down a steep and unconsolidated lava delta. The channelized streams were 0.7-1.5 m across and moved at rates of 1-3 m/s. The estimated flux of a stream was 0.7 m3/s. Jets of hydrothermal water and gas bubbles were associated with the volcanic activity. The rapidly moving channelized lava streams represent a previously undescribed aspect of submarine volcanism. -Author

  10. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, Robert I.

    1987-01-01

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

  11. Transition from circular to stellate forms of submarine volcanoes

    NASA Astrophysics Data System (ADS)

    Mitchell, Neil C.

    2001-02-01

    Large volcanic islands and guyots have stellate forms that reflect the relief of radiating volcanic rift zones, multiple volcanic centers, and embayments due to giant flank failures. Small mid-ocean ridge volcanoes, in contrast, are commonly subcircular in plan view and show only embryonic rift zones. In order to characterize the transition between these two end-members the morphology of 141 seamounts and guyots was studied using the shape of the depth contour at half the height of each edifice. Irregularity was characterized by measuring perimeter distance, elongation, and moment of inertia of the contours, assuming an "ideal" edifice is circular. The analysis reveals a general transition over 2-4 km edifice height (best transition estimate 3 km), while some large edifices 4-5 km high show no major embayments or ridges, suggesting considerable variation in the effectiveness of mechanisms that cause flank instability and growth of rift zones. The various origins of the transition are discussed, and the upper limit of magma chambers, many of which lie above the basement of the larger edifices, is proposed to affect the morphologic complexity via a number of mechanisms and is an important factor affecting the mode of growth. The origins of the truncated cone shape of mid-ocean ridge volcanoes are also discussed. Of the eruption mechanisms that have been proposed to explain their flat summits, the most likely mechanisms involve eruption from small ephemeral magma bodies lying within the low-density upper oceanic crust. The discussion includes speculations on factors affecting the depths of magma chambers beneath oceanic volcanoes. Supporting table is available via Web browser or via Anonymous FTP from ftp://kosmos.agu.org, directory "append" (Username = "anonymous", Password ="guest"); subdirectories in the ftp site are arranged by paper number. Information on searching and submitting electronic supplements is found at http://www.agu.org/pubs/csupp_about.html.

  12. Exploring the "Sharkcano": Biogeochemical observations of the Kavachi submarine volcano (Solomon Islands) using simple, cost-effective methods.

    NASA Astrophysics Data System (ADS)

    Phillips, B. T.; Albert, S.; Carey, S.; DeCiccio, A.; Dunbabin, M.; Flinders, A. F.; Grinham, A. R.; Henning, B.; Howell, C.; Kelley, K. A.; Scott, J. J.

    2015-12-01

    Kavachi is a highly active undersea volcano located in the Western Province of the Solomon Islands, known for its frequent phreatomagmatic eruptions and ephemeral island-forming activity. The remote location of Kavachi and its explosive behavior has restricted scientific exploration of the volcano, limiting observations to surface imagery and peripheral water-column data. An expedition to Kavachi in January 2015 was timed with a rare lull in volcanic activity, allowing for observation of the inside of Kavachi's caldera and its flanks. Here we present medium-resolution bathymetry of the main peak paired with benthic imagery, petrologic analysis of samples from the caldera rim, measurements of gas flux over the main peak, and hydrothermal plume structure data. A second peak was discovered to the Southwest of the main cone and displayed evidence of diffuse-flow venting. Populations of gelatinous animals, small fish, and sharks were observed inside the active crater, raising new questions about the ecology of active submarine volcanoes. Most equipment used in this study was lightweight, relatively low-cost, and deployed using small boats; these methods may offer developing nations an economic means to explore deep-sea environments within their own territorial waters.

  13. Mount Rainier active cascade volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

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

  14. Acoustic stratigraphy and hydrothermal activity within Epi Submarine Caldera, Vanuatu, New Hebrides Arc

    USGS Publications Warehouse

    Greene, H. Gary; Exon, N.F.

    1988-01-01

    Geological and geophysical surveys of active submarine volcanoes offshore and southeast of Epi Island, Vanuatu, New Hebrides Arc, have delineated details of the structure and acoustic stratigraphy of three volcanic cones. These submarine cones, named Epia, Epib, and Epic, are aligned east-west and spaced 3.5 km apart on the rim of a submerged caldera. At least three acoustic sequences, of presumed Quaternary age, can be identified on single-channel seismic-reflection profiles. Rocks dredged from these cones include basalt, dacite, and cognate gabbroic inclusions with magmatic affinities similar to those of the Karua (an active submarine volcano off the southeastern tip of Epi) lavas. ?? 1988 Springer-Verlag New York Inc.

  15. Hydroacoustic detection of submarine landslides on Kilauea Volcano

    NASA Astrophysics Data System (ADS)

    Caplan-Auerbach, Jacqueline; Fox, Christopher G.; Duennebier, Frederick K.

    Landslides produced at the site where lava flows into the ocean at Kilauea volcano have been detected hydroacoustically. Up to 10 landslides per day were detected by a hydrophone on the Hawaii Undersea Geo-Observatory (HUGO), located 50 km south of the entry site. The largest of these landslides, partly subaerial events known as bench collapses, were detected by a network of hydrophones in the eastern Pacific, 5000-7000 km away from the source. The landslides display a characteristic spectral signature easily recognizable among other signals such as earthquake T-phases and anthropogenic noises. The fact that signals are detected at great distances suggests that hydroacoustic detection of landslides could be a powerful tool in tsunami monitoring and modeling efforts.

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

    PubMed

    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%.

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

    PubMed Central

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

    2016-01-01

    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%. PMID:27157062

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

    NASA Astrophysics Data System (ADS)

    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%.

  19. Degassing history of water, sulfur, and carbon in submarine lavas from Kilauea Volcano, Hawaii

    SciTech Connect

    Dixon, J.E.; Stolper, E.M. ); Clague, D.A. )

    1991-05-01

    Major, minor, and dissolved volatile element concentrations were measured in tholeiitic glasses from the submarine portion (Puna Ridge) of the east rift zone of Kilauea Volcano, Hawaii. Dissolved H{sub 2}O and S concentrations display a wide range relative to nonvolatile incompatible elements at all depths. This range cannot be readily explained by fractional crystallization, degassing of H{sub 2}O and S during eruption on the seafloor, or source region heterogeneities. Dissolved CO{sub 2} concentrations, in contrast, show a positive correlation with eruption depth and typically agree within error with the solubility at that depth. The authors propose that most magmas along the Puna Ridge result from (1) mixing of a relatively volatile-rich, undegassed component with magmas that experienced low pressure (perhaps subaerial) degassing during which substantial H{sub 2}O, S, and CO{sub 2} were lost, followed by (2) fractional crystallization of olivine, clinopyroxene, and plagioclase from this mixture to generate a residual liquid; and (3) further degassing, principally of CO{sub 2} for samples erupted deeper than 1,000 m, during eruption on the seafloor. They predict that average Kilauean primary magmas with 16% MgO contain {approximately}0.47 wt % H{sub 2}0, {approximately}900 ppm S, and have {delta}D values of {approximately}{minus}30 to {minus}40%. The model predicts that submarine lavas from wholly submarine volcanoes (i.e., Loihi), for which there is no opportunity to generate the degassed end member by low pressure degassing, will be enriched in volatiles relative to those from volcanoes whose summits have breached the sea surface (i.e., Kilauea and Mauna Loa).

  20. Remote Analysis of Grain Size Characteristic in Submarine Pyroclastic Deposits from Kolumbo Volcano, Greece

    NASA Astrophysics Data System (ADS)

    Smart, C.; Whitesell, D. P.; Roman, C.; Carey, S.

    2011-12-01

    Grain size characteristics of pyroclastic deposits provide valuable information about source eruption energetics and depositional processes. Maximum size and sorting are often used to discriminate between fallout and sediment gravity flow processes during explosive eruptions. In the submarine environment the collection of such data in thick pyroclastic sequences is extremely challenging and potentially time consuming. A method has been developed to extract grain size information from stereo images collected by a remotely operated vehicle (ROV). In the summer of 2010 the ROV Hercules collected a suite of stereo images from a thick pumice sequence in the caldera walls of Kolumbo submarine volcano located about seven kilometers off the coast of Santorini, Greece. The highly stratified, pumice-rich deposit was likely created by the last explosive eruption of the volcano that took place in 1650 AD. Each image was taken from a distance of only a few meters from the outcrop in order to capture the outlines of individual clasts with relatively high resolution. Mosaics of individual images taken as the ROV transected approximately 150 meters of vertical outcrop were used to create large-scale vertical stratigraphic columns that proved useful for overall documentation of the eruption sequence and intracaldera correlations of distinct tephra units. Initial image processing techniques, including morphological operations, edge detection, shape and size estimation were implemented in MatLab and applied to a subset of individual images of the mosiacs. A large variety of algorithms were tested in order to best discriminate the outlines of individual pumices. This proved to be challenging owing to the close packing and overlapping of individual pumices. Preliminary success was achieved in discriminating the outlines of the large particles and measurements were carried out on the largest clasts present at different stratigraphic levels. In addition, semi-quantitative analysis of the

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

    USGS Publications Warehouse

    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.

  2. Historical bathymetric charts and the evolution of Santorini submarine volcano, Greece

    NASA Astrophysics Data System (ADS)

    Watts, A. B.; Nomikou, P.; Moore, J. D. P.; Parks, M. M.; Alexandri, M.

    2015-03-01

    Historical bathymetric charts are a potential resource for better understanding the dynamics of the seafloor and the role of active processes, such as submarine volcanism. The British Admiralty, for example, have been involved in lead line measurements of seafloor depth since the early 1790s. Here, we report on an analysis of historical charts in the region of Santorini volcano, Greece. Repeat lead line surveys in 1848, late 1866, and 1925-1928 as well as multibeam swath bathymetry surveys in 2001 and 2006 have been used to document changes in seafloor depth. These data reveal that the flanks of the Kameni Islands, a dacitic dome complex in the caldera center, have shallowed by up to ˜175 m and deepened by up to ˜80 m since 1848. The largest shallowing occurred between the late 1866 and 1925-1928 surveys and the largest deepening occurred during the 1925-1928 and 2001 and 2006 surveys. The shallowing is attributed to the emplacement of lavas during effusive eruptions in both 1866-1870 and 1925-1928 at rates of up to 0.18 and 0.05 km3 a-1, respectively. The deepening is attributed to a load-induced viscoelastic stress relaxation following the 1866-1870 and 1925-1928 lava eruptions. The elastic thickness and viscosity that best fits the observed deepening are 1.0 km and ˜1016 Pa s, respectively. This parameter pair, which is consistent with the predictions of a shallow magma chamber thermal model, explains both the amplitude and wavelength of the historical bathymetric data and the present day rate of subsidence inferred from InSAR analysis.

  3. Submarine Pyroclastic Flow Deposits; July 2003 Dome Collapse Event of the Soufrière Hills Volcano, Montserrat, West Indies

    NASA Astrophysics Data System (ADS)

    Trofimovs, J.; Sparks, S.; Talling, P.

    2006-12-01

    What happens when pyroclastic flows enter the ocean? To date, the subject of submarine pyroclastic flow behaviour has been controversial. Ambiguity arises from inconclusive evidence of a subaqueous depositional environment in ancient successions, to difficulty in sampling the in situ products of modern eruptions. A research voyage of the RRS James Clark Ross (9-18 May 2005) sampled 52 sites offshore from the volcanic island of Montserrat. The Soufrière Hills volcano, Montserrat, has been active since 1995 with eruptive behaviour dominated by andesite lava dome growth and collapse. Over 90% of the pyroclastic material produced has been deposited into the ocean. In July 2003 the Soufrière Hills volcano produced the largest historically documented dome collapse event. 210 x 106 m3 of pyroclastic material avalanched down the Tar River Valley, southeast Montserrat, to be deposited into the ocean. Bathymetric imaging and coring of offshore pyroclastic deposits, with a specific focus on the July 2003 units, reveals that the pyroclastic flows mix rapidly and violently with the water as they enter the ocean. Mixing takes place between the shore and 500 m depth where the deposition of basal coarse-grained parts of the flow initiates on slopes of 15° or less. The coarse components (pebbles to boulders) are deposited proximally from dense basal slurries to form steep sided, near linear ridges that amalgamate to form a kilometer-scale submarine fan. These proximal deposits contain <1% of ash-grade material. The finer components (dominantly ash-grade) are mixed into the overlying water column to form turbidity currents that flow distances >40 km from source. The total volume of pyroclastic material deposited within the submarine environment during this event exceeds 170 x 106 m3, with 65% deposited in proximal lobes and 35% deposited as distal turbidites. This broadly correlates with the block and ash components respectively, of the source subaerial pyroclastic flow. However

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

    NASA Astrophysics Data System (ADS)

    Fraile-Nuez, Eugenio; Magdalena Santana-Casiano, J.; González-Dávila, Melchor

    2014-05-01

    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.

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:22768379

  7. New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece.

    PubMed

    Kilias, Stephanos P; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Polymenakou, Paraskevi N; Godelitsas, Athanasios; Argyraki, Ariadne; Carey, Steven; Gamaletsos, Platon; Mertzimekis, Theo J; Stathopoulou, Eleni; Goettlicher, Joerg; Steininger, Ralph; Betzelou, Konstantina; Livanos, Isidoros; Christakis, Christos; Bell, Katherine Croff; Scoullos, Michael

    2013-01-01

    We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe(3+)-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe(2+)-oxidation, dependent on microbially produced nitrate.

  8. New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece

    PubMed Central

    Kilias, Stephanos P.; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Polymenakou, Paraskevi N.; Godelitsas, Athanasios; Argyraki, Ariadne; Carey, Steven; Gamaletsos, Platon; Mertzimekis, Theo J.; Stathopoulou, Eleni; Goettlicher, Joerg; Steininger, Ralph; Betzelou, Konstantina; Livanos, Isidoros; Christakis, Christos; Bell, Katherine Croff; Scoullos, Michael

    2013-01-01

    We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe3+-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe2+-oxidation, dependent on microbially produced nitrate. PMID:23939372

  9. Volcanoes.

    ERIC Educational Resources Information Center

    Tilling, Robert I.

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

  10. Submarine Volcaniclastic Deposits Associated with the Minoan Eruption of Santorini volcano, Greece

    NASA Astrophysics Data System (ADS)

    Carey, S.; Sigurdsson, H.; Alexandri, M.; Vougioukalakis, G.; Croff, K.; Roman, C.; Sakellariou, D.; Anagnostou, C.; Rousakis, G.; Ioakim, C.; Gogou, A.; Ballas, D.; Misaridis, T.; Nomikou, P.

    2006-12-01

    The distribution of submarine volcaniclastic deposits has been studied in the Santorini volcanic field by a combination of seismic surveys using a ten cubic inch air-gun, sediment coring and ROV operations. A distinctive sediment sequence has been identified in the uppermost section of the seafloor surrounding Santorini. It is generally massive or chaotic with some irregular internal reflectors. The sequence extends more than 25 km to the west in the Christiana Basin, 22 km to the east in the Anafi Basin, and 28 km to the NE in the Anydros Basin. A mean thickness of about 29 meters is inferred from the seismic records, but is as high as 80 meters locally in areas near the coast of Santorini, where the Minoan pyroclastic flow deposit is up to 40 m thick on land. The sequence has been traced over an area of at least 1378 square kilometers on the sea floor. On the steep submarine slopes of the volcano the sequence often exhibits a terraced or step-like morphology that may reflect downslope creep or slumping during or just after deposition. The massive facies of the sequence was observed to transform abruptly into a laminated or well-bedded, and much thinner facies with distance from source, and with greater overall extent. In many cases this distal facies, which may consist of turbidites, extends beyond the area of the seismic survey lines, or more than 30 km from Santorini. ROV dives on the sediment sequence to the east of Santorini show that it consists of massive pyroclastic flow deposit. By analogy with the seismic character of submarine pyroclastic flows from the 1883 eruption of Krakatau we propose that the widespread sequence is related to the entrance of pyroclastic flows into the sea during the Minoan explosive eruption of Santorini (~3600 yrs. B.P.). A previous estimate of the volume of submarine pyroclastic flow deposits from the Minoan eruption was 20 cubic kilometers (dense rock equivalent, DRE) based on the fractionation of co-ignimbrite ash fall from

  11. Cold seeps associated with a submarine debris avalanche deposit at Kick'em Jenny volcano, Grenada (Lesser Antilles)

    NASA Astrophysics Data System (ADS)

    Carey, Steven; Ballard, Robert; Bell, Katherine L. C.; Bell, Richard J.; Connally, Patrick; Dondin, Frederic; Fuller, Sarah; Gobin, Judith; Miloslavich, Patricia; Phillips, Brennan; Roman, Chris; Seibel, Brad; Siu, Nam; Smart, Clara

    2014-11-01

    Remotely operated vehicle (ROV) exploration at the distal margins of a debris avalanche deposit from Kick'em Jenny submarine volcano in Grenada has revealed areas of cold seeps with chemosynthetic-based ecosystems. The seeps occur on steep slopes of deformed, unconsolidated hemipelagic sediments in water depths between 1952 and 2042 m. Two main areas consist of anastomosing systems of fluid flow that have incised local sediments by several tens of centimeters. No temperature anomalies were observed in the vent areas and no active flow was visually observed, suggesting that the venting may be waning. An Eh sensor deployed on a miniature autonomous plume recorder (MAPR) recorded a positive signal and the presence of live organisms indicates at least some venting is still occurring. The chemosynthetic-based ecosystem included giant mussels (Bathymodiolus sp.) with commensal polychaetes (Branchipolynoe sp.) and cocculinid epibionts, other bivalves, Siboglinida (vestimentiferan) tubeworms, other polychaetes, and shrimp, as well as associated heterotrophs, including gastropods, anemones, crabs, fish, octopods, brittle stars, and holothurians. The origin of the seeps may be related to fluid overpressure generated during the collapse of an ancestral Kick'em Jenny volcano. We suggest that deformation and burial of hemipelagic sediment at the front and base of the advancing debris avalanche led to fluid venting at the distal margin. Such deformation may be a common feature of marine avalanches in a variety of geological environments especially along continental margins, raising the possibility of creating large numbers of ephemeral seep-based ecosystems.

  12. The third Volcano of La Réunion Island : new geochemical data from submarine flanks

    NASA Astrophysics Data System (ADS)

    Smietana, M. S.; Bachèlery, P. B.; Hémond, C. H.

    2009-04-01

    The existence of a third volcano on La Réunion Island, named Les Alizés, was presumed from gravity and magnetic data. This buried volcano is only known by the hypovolcanic complex encountered during a geothermal exploration drilling, beneath the eastern flank of Piton de la Fournaise. Negative magnetic anomalies offshore the north-eastern coast, suggest that the rocks belonging to Les Alizés volcano could be present in this area. In January 2008, a scientific survey onboard the R/V METEOR was carried out offshore La Réunion within the frame of the project ERODER2. During this campaign, submarine basalts were dredged on three rift zones of this intraplate volcanic island (NE and SE rift zones of Piton de la Fournaise volcano, and l'Etang Salé rift zone off the southern flank of Piton des Neiges volcano). The dredged rocks were analyzed for their major and trace element bulk compositions and compared with all available data for both Piton des Neiges and Piton de la Fournaise. Two groups of basaltic lava have been identified. Group 1, which encompasses samples from each rift zone, presents compositions similar to the subaerial basaltic rocks. Group 2, only found in the northern part of the NE rift zone, has higher K2O (1,28-1,44 wt.%), P2O5 (0,35-0,43 wt.%), and La/Sm (4,1-4,2) compared to subaerial and Group 1 lava [K20 (0,61-1,07 wt.%), P2O5 (0,17-0,28 wt.%), La/Sm (3,1-3,8)]. Such characteristics (high K2O, P2O5 and HREE and low SiO2) are exceptional for La Réunion lava and Group 2 composition does not correspond to any known rock from this island. This suggests a possible compositional change during the building of La Réunion edifice that can be indicative of variations in the partial melting processes. Is Les Alizés volcano there?

  13. Flank Collapse Assessment At Kick-'em-Jenny Submarine Volcano (Lesser Antilles): A Combined Approach Using Modelling and Experiments

    NASA Astrophysics Data System (ADS)

    Dondin, Frédéric; Heap, Michael; Robert, Richard E. A.; Dorville, Jean-Francois M.; Carey, Steven

    2016-04-01

    Volcanic landslides - the result of volcanic flank failure - are highly hazardous mass movements due to their high mobility, the wide area they can impact, and their potential to generate tsunamis. In the Lesser Antilles at least 53 episodes of flank collapse have been identified, with many of them associated with voluminous (Vdeposit exceeding 1 km3) submarine volcanic landslide deposits. The existence of such voluminous deposits highlights the hazard of potentially devastating tsunami waves to the populated islands of the Lesser Antilles. To help understand and mitigate such hazards, we applied a relative stability assessment method to the only active submarine volcano of the Lesser Antilles island arc: Kick-'em-Jenny (KeJ). KeJ - located 8 km north of the island of Grenada - is the southernmost edifice in the arc with recognized associated volcanic landslide deposits. From the three identified landslide prehistoric episodes, one is associated with a collapse volume of about 4.4 km3. Numerical simulations considering a single pulse collapse revealed that this episode would have produced a regional tsunami. A volume estimate of the present day edifice is about 1.5 km3. We aim to quantify potential initial volumes of collapsed material using relative instability analysis (RIA). The RIA evaluates the critical potential failure surface associated with factor of safety (Fs) inferior to 1 and compares them to areas of deficit/surplus of mass/volume obtained from the comparison of an high resolution digital elevation model of the edifice with an ideal 3D surface named Volcanoid. To do so we use freeware programs VolcanoFit 2.0 and SSAP 4.5. We report, for the first time, results of a Limit Equilibrium Method (Janbu's rigorous method) as a slope stability computation analysis performed using geomechanical parameters retrieved from rock mechanics tests performed on two rock basaltic-andesite rock samples collected from within the crater of the volcano during the 1

  14. Bacterial diversity in Fe-rich hydrothermal sediments at two South Tonga Arc submarine volcanoes.

    PubMed

    Forget, N L; Murdock, S A; Juniper, S K

    2010-12-01

    Seafloor iron oxide deposits are a common feature of submarine hydrothermal systems. Morphological study of these deposits has led investigators to suggest a microbiological role in their formation, through the oxidation of reduced Fe in hydrothermal fluids. Fe-oxidizing bacteria, including the recently described Zetaproteobacteria, have been isolated from a few of these deposits but generally little is known about the microbial diversity associated with this habitat. In this study, we characterized bacterial diversity in two Fe oxide samples collected on the seafloor of Volcanoes 1 and 19 on the South Tonga Arc. We were particularly interested in confirming the presence of Zetaproteobacteria at these two sites and in documenting the diversity of groups other than Fe oxidizers. Our results (small subunit rRNA gene sequence data) showed a surprisingly high bacterial diversity, with 150 operational taxonomic units belonging to 19 distinct taxonomic groups. Both samples were dominated by Zetaproteobacteria Fe oxidizers. This group was most abundant at Volcano 1, where sediments were richer in Fe and contained more crystalline forms of Fe oxides. Other groups of bacteria found at these two sites include known S- and a few N-metabolizing bacteria, all ubiquitous in marine environments. The low similarity of our clones with the GenBank database suggests that new species and perhaps new families were recovered. The results of this study suggest that Fe-rich hydrothermal sediments, while dominated by Fe oxidizers, can be exploited by a variety of autotrophic and heterotrophic micro-organisms.

  15. Modelling submarine pyroclastic flows at the Soufrière Hills volcano, Montserrat

    NASA Astrophysics Data System (ADS)

    Hogg, A. J.; Goater, A.

    2011-12-01

    Submarine sedimentary flows are notoriously difficult to observe directly and interpreting their deposits to gain insight to the parent flows can be problematic. Pyroclastic flows from the Soufrière Hills volcano, Montserrat, which entered the ocean and deposited particles over the sea bed are a notable exception. In this case, from monitoring of the volcano, the mass of particulate released and the duration of the flow can be estimated accurately. Furthermore research cruises have imaged, cored the ocean bed and measured the distribution and composition of the deposit left by these flows over much of their runout. These observations therefore form a unique dataset in which both source conditions and final deposit are relatively well constrained. Mathematically modelling long runout sedimentary flows can also present several difficulties. Over these length and time scales, it is not feasible to simulate directly all of the fluid and particulate motions and so reduced models have been developed to capture the dominant processes and features of the flows. These have often been calibrated by laboratory scale experiments - but now with this data from the Soufrière Hills volcano, it is possible to compare model predictions with a natural scale event. Our model is based upon a shallow layer formulation, assuming hydrostatic balance in the vertical to leading order. The downslope motion of the sediment-laden fluid is driven by gravitational forces, associated with the density difference between the intruding and surrounding fluid. Particles settle out of the current to the underlying boundary, reducing the density difference, slowing the motion and forming the deposit. We develop a model that expresses conservation of fluid and particulate mass and a balance of streamwise momentum. This system of equations is integrated numerically to reveal the temporal and spatial evolution and asymptotic methods are used to reveal the dynamical controls on the runout. The theoretical

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Seismic Activity at Vailulu'u, Samoa's Youngest Volcano

    NASA Astrophysics Data System (ADS)

    Konter, J.; Staudigel, H.; Hart, S.

    2002-12-01

    Submarine volcanic systems, as a product of the Earth's mantle, play an essential role in the Earth's heat budget and in the interaction between the solid Earth and the hydrosphere and biosphere. Their eruptive and intrusive activity exerts an important control on these hydrothermal systems. In March 2000, we deployed an array of five ocean bottom hydrophones (OBH) on the summit region (625-995 m water depth) of Vailulu'u Volcano (14°12.9'S;169°03.5'W); this volcano represents the active end of the Samoan hotspot chain and is one of only a few well-studied intra-plate submarine volcanoes. We monitored seismic activity for up to 12 months at low sample rate (25 Hz), and for shorter times at a higher sample rate (125 Hz). We have begun to catalogue and locate a variety of acoustic events from this network. Ambient ocean noise was filtered out by a 4th-order Butterworth bandpass filter (2.3 - 10 Hz). We distinguish small local earthquakes from teleseismic activity, mostly identified by T- (acoustic) waves, by comparison with a nearby GSN station (AFI). Most of the detected events are T-phases from teleseismic earthquakes, characterized by their emergent coda and high frequency content (up to 30 Hz); the latter distinguishes them from low frequency emergent signals associated with the volcano (e.g. tremor). A second type of event is characterized by impulsive arrivals, with coda lasting a few seconds. The differences in arrival times between stations on the volcano are too small for these events to be T-waves; they are very likely to be local events, since the GSN station in Western Samoa (AFI) shows no arrivals close in time to these events. Preliminary locations show that these small events occur approximately once per day and are located within the volcano (the 95% confidence ellipse is similar to the size of the volcano, due to the small size of the OBH network). Several events are located relatively close to each other (within a km radius) just NW of the crater.

  18. Growth and collapse of Waianae volcano, Hawaii, as revealed by exploration of its submarine flanks

    USGS Publications Warehouse

    Coombs, Michelle L.; Clague, David A.; Moore, Gregory F.; Cousens, Brian L.

    2004-01-01

    Wai‘anae Volcano comprises the western half of O‘ahu Island, but until recently little was known about the submarine portion of this volcano. Seven new submersible dives, conducted in 2001 and 2002, and multibeam bathymetry offshore of Wai‘anae provide evidence pertaining to the overall growth of the volcano's edifice as well as the timing of collapses that formed the Wai‘anae slump complex. A prominent slope break at ∼1400 mbsl marks the paleoshoreline of Wai‘anae at the end of its shield-building stage and wraps around Ka‘ena Ridge, suggesting that this may have been an extension of Wai‘anae's northwest rift zone. Subaerially erupted tholeiitic lavas were collected from a small shield along the crest of Ka‘ena Ridge. The length of Wai‘anae's south rift zone is poorly constrained but reaches at least 65 km on the basis of recovered tholeiite pillows at this distance from the volcano's center. Wai‘anae's growth was marked by multiple collapse and deformation events during and after its shield stage, resulting in the compound mass wasting features on the volcano's southwest flank (Wai‘anae slump complex). The slump complex, one of the largest in Hawai‘i, covering an area of ∼5500 km2, is composed of several distinct sections on the basis of morphology and the lithologies of recovered samples. Two dives ascended the outer bench of the slump complex and collected predominantly low-S tholeiites that correlate with subaerial lavas erupted early during the volcano's shield stage, from 3.9 to 3.5 Ma. Pillow lavas from the outer bench have Pb, Sr, and Nd isotopic values that overlap with previously published subaerial Wai‘anae lavas. On the basis of the compositions of the recovered samples, the main body of the slump complex, as represented by the outer bench, probably formed during and shortly after the early shield stage. To the southwest of the outer bench lies a broad debris field on the seafloor, interpreted to have formed by a

  19. Hydrothermal mineralization at Kick'em Jenny submarine volcano in the Lesser Antilles island arc

    NASA Astrophysics Data System (ADS)

    Olsen, R.; Carey, S.; Sigurdsson, H.; Cornell, W. C.

    2011-12-01

    Kick 'em Jenny (KeJ) is an active submarine volcano located in the Lesser Antilles island arc, ~7.5 km northwest of Grenada. Of the twelve eruptions detected since 1939, most have been explosive as evidenced by eyewitness accounts in 1939, 1974, and 1988 and the dominance of explosive eruption products recovered by dredging. In 2003, vigorous hydrothermal activity was observed in the crater of KeJ. Video footage taken by a remotely operated vehicle (ROV) during the cruise RB-03-03 of the R/V Ronald Brown documented the venting of a vapor phase in the form of bubbles that ascended through the water column and a clear fluid phase in the form of shimmering water. The shimmering water generally ascended through the water column but can also been seen flowing down gradient from a fissure at the top of a fine-grained sediment mound. These fine-grained sediment mounds are the only structure associated with hydrothermal venting; spire or chimney structures were not observed. Hydrothermal venting was also observed coming from patches of coarse-grained volcaniclastic sediment on the crater floor and from talus slopes around the perimeter of the crater. Samples were collected from these areas and from areas void of hydrothermal activity. XRD and ICPMS analyses of bulk sediment were carried out to investigate the geochemical relationships between sediment types. Sediment samples from the hydrothermal mound structures are comprised of the same components (plagioclase, amphibole, pyroxene, and scoria) as sediment samples from areas void of hydrothermal activity (primary volcaniclastic sediment) in the 500-63 μm size range. High resolution grain size analyses show that >78% of sediment in the hydrothermal mound samples are between 63-2 μm with 6-20% clay sized (<2 μm) whereas <40% of the primary volcaniclastic sediment is between 63-2 μm with ~2% clay sized. The presence of clay minerals (smectite, illite, talc, and I/S mixed layer) in the hydrothermal mound samples was

  20. Deployment of a seismic array for volcano monitoring during the ongoing submarine eruption at El Hierro, Canary Islands

    NASA Astrophysics Data System (ADS)

    Abella, R.; Almendros, J.; Carmona, E.; Martin, R.

    2012-04-01

    On 17 July 2011 there was an important increase of the seismic activity at El Hierro (Canary Islands, Spain). This increase was detected by the Volcano Monitoring Network (Spanish national seismic network) run by the Instituto Geográfico Nacional (IGN). As a consequence, the IGN immediately deployed a dense, complete monitoring network that included seismometers, GPS stations, geochemical equipment, magnetometers, and gravity meters. During the first three months of activity, the seismic network recorded over ten thousand volcano-tectonic earthquakes, with a maximum magnitude of 4.6. On 10 October 2011 an intense volcanic tremor started. It was a monochromatic signal, with variable amplitude and frequency content centered at about 1-2 Hz. The tremor onset was correlated with the initial stages of the submarine eruption that occurred from a vent located south of El Hierro island, near the village of La Restinga. At that point the IGN, in collaboration with the Instituto Andaluz de Geofísica, deployed a seismic array intended for volcanic tremor monitoring and analysis. The seismic array is located about 7 km NW of the submarine vent. It has a 12-channel, 24-bit data acquisition system sampling each channel at 100 sps. The array is composed by 1 three-component and 9 vertical-component seismometers, distributed in a flat area with an aperture of 360 m. The data provided by the seismic array are going to be processed using two different approaches: (1) near-real-time, to produce information that can be useful in the management of the volcanic crisis; and (2) detailed investigations, to study the volcanic tremor characteristics and relate them to the eruption dynamics. At this stage we are mostly dedicated to produce fast, near-real-time estimates. Preliminary results have been obtained using the maximum average cross-correlation method. They indicate that the tremor wavefronts are highly coherent among array stations and propagate across the seismic array with an

  1. Transport and Deposition During The 2012 Submarine Explosive Eruption of Havre Volcano

    NASA Astrophysics Data System (ADS)

    Soule, S. A.; Carey, R.; Jones, M.; Ikegami, F.; Yoerger, D.; Fornari, D. J.

    2015-12-01

    Havre Volcano in the Kermadec Arc experienced a large eruption in 2012. The eruption was identified when ships in the area intersected a pumice raft, which was subsequently tracked by NASA MODIS satellite imagery. In 2015, an NSF-sponsored research cruise to the area conducted AUV and ROV dives to map and sample the deposits of this eruption. This presentation describes the high-resolution mapping data and seafloor observations that illustrate the processes of lava and pyroclast transport and deposition. The National Deep Submergence Facility (NDSF) AUV Sentry collected multibeam bathymetry data over the Havre caldera rim and floor - an area of 56 km2 - at a resolution of 1m. In addition, Sentry collected high-resolution sidescan sonar backscatter data over the same area. The NDSF ROV Jason collected HD video and down-looking still imagery along dive transects. These data allow us to document the depositional landforms in great detail. Notable features include effusive domes, lava flows, and a widespread blanket of giant pumice and ash. With constraints from seafloor imagery, we use the morphology of the imaged landforms to delineate deposit extents, identify intra-flow and intra-deposit features, pinpoint vent locations, and, in comparison with pre-eruption bathymetry, determine eruptive volumes. This information informs preliminary models of transport and deposition processes that are unique to submarine explosive eruptions.

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

    NASA Astrophysics Data System (ADS)

    Fraile-Nuez, E.; Santana-Casiano, J.; Gonzalez-Davila, M.

    2013-12-01

    On October 10 2011 an underwater eruption gave rise to a novel shallow submarine volcano south of the island of El Hierro, Canary Islands, Spain. During the eruption large quantities of mantle-derived gases, solutes and heat were released into the surrounding waters. In order to monitor the impact of the eruption on the marine ecosystem, periodic multidisciplinary cruises were carried out. Here, we present an initial report of the extreme physical-chemical perturbations caused by this event, comprising thermal changes, water acidification, deoxygenation and metal-enrichment, which resulted in significant alterations to the activity and composition of local plankton communities. Our findings highlight the potential role of this eruptive process as a natural ecosystem-scale experiment for the study of extreme effects of global change stressors on marine environments. (A) Natural color composite from the MEdium Resolution Imaging Spectrometer (MERIS) instrument aboard ENVISAT Satellite (European Space Agency), (November 9, 2011 at 14:45 UTC). Remote sensing data have been used to monitor the evolution of the volcanic emissions, playing a fundamental role during field cruises in guiding the Spanish government oceanographic vessel to the appropriate sampling areas. The inset map shows the position of Canary Islands west of Africa and the study area (solid white box). (B) Location of the stations carried out from November 2011 to February 2012 at El Hierro. Black lines denote transects A-B and C-D.

  3. Flank instability assessment at Kick-'em-Jenny submarine volcano (Grenada, Lesser Antilles): a multidisciplinary approach using experiments and modeling

    NASA Astrophysics Data System (ADS)

    Dondin, F. J.-Y.; Heap, M. J.; Robertson, R. E. A.; Dorville, J.-F. M.; Carey, S.

    2017-01-01

    Kick-'em-Jenny (KeJ)—located ca. 8 km north of the island of Grenada—is the only active submarine volcano of the Lesser Antilles Volcanic Arc. Previous investigations of KeJ revealed that it lies within a collapse scar inherited from a past flank instability episode. To assess the likelihood of future collapse, we employ here a combined laboratory and modeling approach. Lavas collected using a remotely operated vehicle (ROV) provided samples to perform the first rock physical property measurements for the materials comprising the KeJ edifice. Uniaxial and triaxial deformation experiments showed that the dominant failure mode within the edifice host rock is brittle. Edifice fractures (such as those at Champagne Vent) will therefore assist the outgassing of the nearby magma-filled conduit, favoring effusive behavior. These laboratory data were then used as input parameters in models of slope stability. First, relative slope stability analysis revealed that the SW to N sector of the volcano displays a deficit of mass/volume with respect to a volcanoid (ideal 3D surface). Slope stability analysis using a limit equilibrium method (LEM) showed that KeJ is currently stable, since all values of stability factor or factor of safety (Fs) are greater than unity. The lowest values of Fs were found for the SW-NW sector of the volcano (the sector displaying a mass/volume deficit). Although currently stable, KeJ may become unstable in the future. Instability (severe reductions in Fs) could result, for example, from overpressurization due to the growth of a cryptodome. Our modeling has shown that instability-induced flank collapse will most likely initiate from the SW-NW sector of KeJ, therefore mobilizing a volume of at least ca. 0.7 km3. The mobilization of ca. 0.7 km3 of material is certainly capable of generating a tsunami that poses a significant hazard to the southern islands of the West Indies.

  4. Active Deformation of Etna Volcano Combing IFSAR and GPS data

    NASA Technical Reports Server (NTRS)

    Lundgren, Paul

    1997-01-01

    The surface deformation of an active volcano is an important indicator of its eruptive state and its hazard potential. Mount Etna volcano in Sicily is a very active volcano with well documented eruption episodes.

  5. 40Ar/39Ar geochronology of submarine Mauna Loa volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Jicha, Brian R.; Rhodes, J. Michael; Singer, Brad S.; Garcia, Michael O.

    2012-09-01

    New geochronologic constraints refine the growth history of Mauna Loa volcano and enhance interpretations of the petrologic, geochemical, and isotopic evolution of Hawaiian magmatism. We report results of 40Ar/39Ar incremental heating experiments on low-K, tholeiitic lavas from the 1.6 km high Kahuku landslide scarp cutting Mauna Loa's submarine southwest rift zone, and from lavas in a deeper section of the rift. Obtaining precise40Ar/39Ar ages from young, tholeiitic lavas containing only 0.2-0.3 wt.% K2O is challenging due to their extremely low radiogenic 40Ar contents. Analyses of groundmass from 45 lavas yield 14 new age determinations (31% success rate) with plateau and isochron ages that agree with stratigraphic constraints. Lavas collected from a 1250 m thick section in the landslide scarp headwall were all erupted around 470 ± 10 ka, implying an extraordinary period of accumulation of ˜25 mm/yr, possibly correlating with the peak of the shield-building stage. This rate is three times higher than the estimated vertical lava accumulation rate for shield-building at Mauna Kea (8.6 ± 3.1 mm/yr) based on results from the Hawaii Scientific Drilling Project. Between ˜470 and 273 ka, the lava accumulation rate along the southwest rift zone decreased dramatically to ˜1 mm/yr. We propose that the marked reduction in lava accumulation rate does not mark the onset of post-shield volcanism as previously suggested, but rather indicates the upward migration of the magma system as Mauna Loa evolved from a submarine stage of growth to one that is predominantly subaerial, thereby cutting off supply to the distal rift zone. Prior to ˜250 ka, lavas with Loihi-like isotopic signatures were erupted along with lavas having typical Mauna Loa values, implying greater heterogeneity in the plume source earlier in Mauna Loa's growth. In addition to refining accumulation rates and the isotopic evolution of the lavas erupted along the southwest rift zone, our new40Ar/39Ar results

  6. Insights on volcanic behaviour from the 2015 July 23-24 T-phase signals generated by eruptions at Kick-'em-Jenny Submarine Volcano, Grenada, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Dondin, F. J. Y.; Latchman, J. L.; Robertson, R. E. A.; Lynch, L.; Stewart, R.; Smith, P.; Ramsingh, C.; Nath, N.; Ramsingh, H.; Ash, C.

    2015-12-01

    Kick-'em-Jenny volcano (KeJ) is the only known active submarine volcano in the Lesser Antilles Arc. Since 1939, the year it revealed itself, and until the volcano-seismic unrest of 2015 July 11-25 , the volcano has erupted 12 times. Only two eruptions breached the surface: 1939, 1974. The volcano has an average eruption cycle of about 10-11 years. Excluding the Montserrat, Soufrière Hills, KeJ is the most active volcano in the Lesser Antilles arc. The University of the West Indies, Seismic Research Centre (SRC) has been monitoring KeJ since 1953. On July 23 and 24 at 1:42 am and 0:02 am local time, respectively, the SRC recorded T-phase signals , considered to have been generated by KeJ. Both signals were recorded at seismic stations in and north of Grenada: SRC seismic stations as well as the French volcano observatories in Guadeloupe and Martinique, Montserrat Volcano Observatory, and the Puerto Rico Seismic Network. These distant recordings, along with the experience of similar observations in previous eruptions, allowed the SRC to confirm that two explosive eruptions occurred in this episode at KeJ. Up to two days after the second eruption, when aerial surveillance was done, there was no evidence of activity at the surface. During the instrumental era, eruptions of the KeJ have been identified from T-phases recorded at seismic stations from Trinidad, in the south, to Puerto Rico, in the north. In the 2015 July eruption episode, the seismic station in Trinidad did not record T-phases associated with the KeJ eruptions. In this study we compare the T-phase signals of 2015 July with those recorded in KeJ eruptions up to 1974 to explore possible causative features for the T-phase recording pattern in KeJ eruptions. In particular, we investigate the potential role played by the Sound Fixing and Ranging (SOFAR) layer in influencing the absence of the T-phase on the Trinidad seismic station during this eruption.

  7. Unravelling the Geometry of Unstable Flanks of Submarine Volcanoes by Magnetic Investigation: the Case of the "sciara del Fuoco" Scar (stromboli Volcano, Aeolian Islands)

    NASA Astrophysics Data System (ADS)

    Muccini, F.; Cocchi, L.; Carmisciano, C.; Speranza, F.; Marziani, F.

    2012-12-01

    Stromboli is the easternmost island of the Aeolian Archipelago (Tyrrhenian Sea) and one of the most active Mediterranean volcanoes. The volcanic edifice rises over 3000 m above the surrounding seafloor, from a depth of about 2000 m b.s.l. to 924 m a.s.l. The north-western flank of volcano is deeply scarred by a destructive collapse event occurred ca. 5000 years ago, and forming a big horseshoe-shaped depression, known as "Sciara del Fuoco" (SdF). This depression, 3 Km long and 2 Km wide, is supposed to extend into the sea down to 700 m b.s.l., while further basinward it turns into a fan-shaped mounted deposit down to about 2600 m b.s.l., where it merges the so-called "Stromboli Canyon". Since its formation, emerged and submerged portions of the SdF have been progressively filled by the volcanic products of the persistent activity of the Stromboli Volcano. In the last 10 years, two paroxysmal eruptions occurred in the Stromboli Volcano, during 2002-2003 and February-April 2007. During both events, the SdF has been partially covered by lava flows and affected by slope failures, also causing (for the 2002-2003 event) a local tsunami. Since the 1990's, and especially after the last two paroxysms, the submerged extension of the SdF has been intensively investigated by using swath bathymetry data. We focused principally on the magnetic anomaly pattern of the submerged SdF since the chaotic depositional system virtually cancels magnetic remanence (which at Stromboli can reach 5-10 A/m values), thus lowering magnetic residual intensity. On July 2012 we acquired new detailed sea-surface magnetic data of the SdF from the shoreline to about 7 km offshore, where the depth is more than 1800 m b.s.l. We collected data thanks to the Italian Navy ship "Nave Aretusa" and by using the Marine Magnetics SeaSPY magnetometer. At the same time, new bathymetric data were acquired in the same area by using a Kongsberg Marine multibeam systems. Although the morphologic features of the

  8. Hydrothermal Venting at Kick'Em Jenny Submarine Volcano (West Indies)

    NASA Astrophysics Data System (ADS)

    Carey, S.; Croff Bell, K. L.; Dondin, F. J. Y.; Roman, C.; Smart, C.; Lilley, M. D.; Lupton, J. E.; Ballard, R. D.

    2014-12-01

    Kick'em Jenny is a frequently-erupting, shallow submarine volcano located ~8 km off the northwest coast of Grenada in the West Indies. The last eruption took place in 2001 but did not breach the sea surface. Focused and diffuse hydrothermal venting is taking place mainly within a small (~100 x 100 m) depression within the 300 m diameter crater of the volcano at depths of about 265 meters. Near the center of the depression clear fluids are being discharged from a focused mound-like vent at a maximum temperature of 180o C with the simultaneous discharge of numerous bubble streams. The gas consists of 93-96% CO2 with trace amounts of methane and hydrogen. A sulfur component likely contributes 1-4% of the gas total. Gas flux measurements on individual bubble streams ranged from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5 to 35o C above ambient occurs throughout the depression and over large areas of the main crater. These zones are extensively colonized by reddish-yellow bacterial mats with the production of loose Fe-oxyhydroxides largely as a surface coating and in some cases, as fragile spires up to several meters in height. A high-resolution photo mosaic of the crater depression was constructed using the remotely operated vehicle Hercules on cruise NA039 of the E/V Nautilus. The image revealed prominent fluid flow patterns descending the sides of the depression towards the base. We speculate that the negatively buoyant fluid flow may be the result of second boiling of hydrothermal fluids at Kick'em Jenny generating a dense saline component that does not rise despite its elevated temperature. Increased density may also be the result of high dissolved CO2 content of the fluids, although we were not able to measure this directly. The low amount of sulphide mineralization on the crater floor suggests that deposition may be occurring mostly subsurface, in accord with models of second boiling mineralization from other hydrothermal vent systems.

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

    PubMed

    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)).

  10. A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc.

    PubMed

    Klaver, Martijn; Carey, Steven; Nomikou, Paraskevi; Smet, Ingrid; Godelitsas, Athanasios; Vroon, Pieter

    2016-08-01

    This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely-operated vehicle that were analyzed for major element, trace element and Sr-Nd-Hf-Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave-bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52-60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low (206)Pb/(204)Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field.

  11. A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc

    NASA Astrophysics Data System (ADS)

    Klaver, Martijn; Carey, Steven; Nomikou, Paraskevi; Smet, Ingrid; Godelitsas, Athanasios; Vroon, Pieter

    2016-08-01

    This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely-operated vehicle that were analyzed for major element, trace element and Sr-Nd-Hf-Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave-bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52-60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low 206Pb/204Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field.

  12. A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc

    PubMed Central

    Carey, Steven; Nomikou, Paraskevi; Smet, Ingrid; Godelitsas, Athanasios; Vroon, Pieter

    2016-01-01

    Abstract This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely‐operated vehicle that were analyzed for major element, trace element and Sr‐Nd‐Hf‐Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave‐bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52–60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low 206Pb/204Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field. PMID:27917071

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Motivations for muon radiography of active volcanoes

    NASA Astrophysics Data System (ADS)

    Macedonio, G.; Martini, M.

    2010-02-01

    Muon radiography represents an innovative tool for investigating the interior of active volcanoes. This method integrates the conventional geophysical techniques and provides an independent way to estimate the density of the volcano structure and reveal the presence of magma conduits. The experience from the pioneer experiments performed at Mt. Asama, Mt. West Iwate, and Showa-Shinzan (Japan) are very encouraging. Muon radiography could be applied, in principle, at any stratovolcano. Here we focus our attention on Vesuvius and Stromboli (Italy).

  15. Episodic massive mud eruptions from submarine mud volcanoes examined through topographical signatures

    NASA Astrophysics Data System (ADS)

    Kioka, Arata; Ashi, Juichiro

    2015-10-01

    The role of mud volcanism on subsurface fluid migration and material cycling has long been debated. Here we compile the heights and radii of offshore mud volcanoes and estimate a mean volume of episodic massive mud eruptions based on previous studies into granular flows. The volume is estimated as a function of the ratio of height to basal radius of the mud volcano's body under reasonable assumptions of the sizes of the mud conduit. Nearly all known offshore mud volcanoes are found to be polygenetic with the mean individual eruption volume of the pie-type mud volcano being several orders of magnitude larger than that of the cone type. The frequent occurrence of pie-type mud volcanoes in accretionary margins characterized by high-sediment influx is explained by their efficiency in the transport of large amounts of fluidized sediments from deep depths to the seafloor.

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

    PubMed

    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.

  17. Active control of radiated pressure of a submarine hull

    NASA Astrophysics Data System (ADS)

    Pan, Xia; Tso, Yan; Juniper, Ross

    2008-03-01

    A theoretical analysis of the active control of low-frequency radiated pressure from submarine hulls is presented. Two typical hull models are examined in this paper. Each model consists of a water-loaded cylindrical shell with a hemispherical shell at one end and conical shell at the other end, which forms a simple model of a submarine hull. The conical end is excited by an axial force to simulate propeller excitations while the other end is free. The control action is implemented through a Tee-sectioned circumferential stiffener driven by pairs of PZT stack actuators. These actuators are located under the flange of the stiffener and driven out of phase to produce a control moment. A number of cost functions for minimizing the radiated pressure are examined. In general, it was found that the control system was capable of reducing more than half of the total radiated pressure from each of the submarine hull for the first three axial modes.

  18. Quantifying submarine landslide processes driven by active tectonic forcing: Cook Strait submarine canyon, New Zealand.

    NASA Astrophysics Data System (ADS)

    Mountjoy, J. J.; Barnes, P. M.; Pettinga, J. R.

    2006-12-01

    The Cook Strait submarine canyon system is a multi-branched, deeply incised and highly sinuous feature of New Zealand's active margin, covering some 1500km2 of sea floor between the North and South Islands and spanning water depths of between 50 and 2700m. The canyon occurs at the transition from the westward dipping oblique subduction zone adjacent to the SE North Island and the zone of continental transpression in NE South Island. The recent acquisition of high resolution (5-10m) SIMRAD EM300 bathymetric data allows active tectonic and geomorphic processes to be assessed and quantified at a level of detail previously not possible. While multiple active submarine fault traces have been identified in the Cook Strait by previous studies, quantitative information on their activity has been limited. Cook Strait is structurally characterized by westward dipping thrust faults and E-W trending dextral strike slip faults. The multiple large magnitude high frequency earthquake sources define zones of very high ground shaking expected to contribute to triggering of extensive submarine slope failures. Landslide activity within the canyon system is widespread and represents the dominant mass movement process affecting canyon heads and walls, redistributing material into valley fills. Complexes of large (km3) multi-stepped, deep-seated (100m) translational bedding plane failures represented by gently sloping (<3°) evacuated slide-scar areas with associated blocky valley fill deposits are numerous. Steep catchment heads, channel walls and the leading edges of asymmetric thrust-fault driven anticlines are dominated by gulley and rill systems with associated eroded and/or incipient slump features. Large (107m3+) slide blocks are recognized in discrete failures with quantifiable displacement vectors. Tsunamigenic landslides in this environment are inevitable. This study will provide quantification of landslide models including triggering mechanisms, discrete geometries and

  19. Volcanoes!

    USGS Publications Warehouse

    ,

    1997-01-01

    Volcanoes is an interdisciplinary set of materials for grades 4-8. Through the story of the 1980 eruption of Mount St. Helens, students will answer fundamental questions about volcanoes: "What is a volcano?" "Where do volcanoes occur and why?" "What are the effects of volcanoes on the Earth system?" "What are the risks and the benefits of living near volcanoes?" "Can scientists forecast volcanic eruptions?"

  20. 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

    NASA Astrophysics Data System (ADS)

    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

  1. Assessment of ambulatory activity in the Republic of Korea Navy submarine crew.

    PubMed

    Choi, Seong-Woo; Lee, Jae-Ho; Jang, Young-Keun; Kim, Jung-Ryul

    2010-01-01

    A submarine crew in the Republic of the Korea Navy experienced significant physical inactivity during undersea deployment because of the narrow and confined space. Physical inactivity is known to be associated with a number of adverse health conditions in the long-term perspective. This study aimed to assess the ambulatory activity of submarine crew using pedometers. Study subjects (n=109) were the submarine crew from two diesel submarines and personnel from the Submarine Command. The subjects wore pedometers at their waistline and recorded their walking steps daily for a month. The submarine crew walked more than 7000 steps/day on average during the stationed period. However, the ambulatory activity of the submarine crew greatly declined to a level of around 2000 steps/day during deployment, which corresponded to the sedentary status category. Active exercise is recommended for the submarine crew to prevent potential adverse health outcomes related to the physical inactivity.

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

    PubMed

    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.

  3. Magnitude and Recurrence of Submarine Landslides: Active vs. Passive Margins

    NASA Astrophysics Data System (ADS)

    Urgeles, Roger; Camerlenghi, Angelo

    2016-04-01

    Submarine landslides are ubiquitous along Mediterranean continental margins. With the aim of understanding mass-wasting processes and related hazard at the scale of a large marine basin encompassing multiple geological settings, we have compiled data on their geometry, age, and trigger mechanism with a geographic information system. The distribution of submarine landslides in the Mediterranean reveals that major deltaic wedges have a higher density of large submarine landslides, while tectonically active margins are characterized by relatively small failures. In all areas, landslide size distributions display power law scaling for landslides > 1 km3. We find consistent differences on the exponent of the power law (θ) depending on the tectonic setting. Active margins present steep slopes of the frequency-magnitude relationship while passive margins tend to display gentler slopes. This pattern likely responds to the common view that tectonically active margins have numerous but small failures, while passive margins have larger but fewer failures. Available age information suggests that failures exceeding 1000 km3 are infrequent and may recur every ~40 kyr. Smaller failures that can still cause significant damage might be relatively frequent (failures > 1 km3 may recur every 40 years). The database highlights that our knowledge of submarine landslide activity with time is limited to a few tens of thousands of years. Available data suggest that submarine landslides may preferentially occur during lowstand periods, but no firm conclusion can be made on this respect, as only 70 landslides (out of 696 in the database) have relatively accurate age determinations. The temporal pattern and changes in frequency-magnitude distribution suggest that sedimentation patterns and pore pressure development have had a major role in triggering slope failures and control the sediment flux from mass wasting to the deep basin.

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

    NASA Astrophysics Data System (ADS)

    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

  5. Submarine evidence of a debris avalanche deposit on the eastern slope of Santorini volcano, Greece

    NASA Astrophysics Data System (ADS)

    Bell, Katherine Lynn Croff; Carey, Steven N.; Nomikou, Paraskevi; Sigurdsson, Haraldur; Sakellariou, Dimitris

    2013-06-01

    Hummocky seafloor features were discovered on the eastern flank of Santorini volcano, Greece. Multibeam bathymetric mapping, airgun seismic profiling, side scan sonar survey, and remotely operated vehicle (ROV) dives have been carried out to characterize the nature of the hummocks. These hummocks appear to be composed of several tens of blocks that are up to several hundred meters in diameter, and are the surface expression of a much larger deposit than is observed in the bathymetry. The sidescan and airgun data show that the deposit covers an area of approximately 6 km wide by 20 km long, and is up to 75 m thick. We estimate the total volume of the deposit to be approximately 4.4 × 109 m3. Sampling of these blocks show they are composed of pyroclastic flow deposits produced during the Minoan eruption of Santorini (ca. 3600 BP). We propose that the deposit is the result of a multi-stage landslide event that was caused by one of the several large earthquakes or volcanic eruptions that have occurred in the vicinity of Santorini since the Minoan eruption. One or more of these events likely triggered the destabilization of a part of the eastern flank of Santorini, which led to a debris avalanche, depositing blocks and forming a hummocky terrain at the base of the island's slope. The mass movement later evolved into a turbulent suspension flow that traveled 20 km or more from the presumed initial failure. Given the size of the landslide deposit, it might have a tsunami potentially affecting the islands across the southern Aegean Sea. The understanding of earthquake-landslide dynamics has important implications for hazard assessment in this seismically active, historical, and highly populated region of the world.

  6. Source of the tsunami generated by the 1650 AD eruption of Kolumbo submarine volcano (Aegean Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Ulvrova, Martina; Paris, R.; Nomikou, P.; Kelfoun, K.; Leibrandt, S.; Tappin, D. R.; McCoy, F. W.

    2016-07-01

    The 1650 AD explosive eruption of Kolumbo submarine volcano (Aegean Sea, Greece) generated a destructive tsunami. In this paper we propose a source mechanism of this poorly documented tsunami using both geological investigations and numerical simulations. Sedimentary evidence of the 1650 AD tsunami was found along the coast of Santorini Island at maximum altitudes ranging between 3.5 m a.s.l. (Perissa, southern coast) and 20 m a.s.l. (Monolithos, eastern coast), corresponding to a minimum inundation of 360 and 630 m respectively. Tsunami deposits consist of an irregular 5 to 30 cm thick layer of dark grey sand that overlies pumiceous deposits erupted during the Minoan eruption and are found at depths of 30-50 cm below the surface. Composition of the tsunami sand is similar to the composition of the present-day beach sand but differs from the pumiceous gravelly deposits on which it rests. The spatial distribution of the tsunami deposits was compared to available historical records and to the results of numerical simulations of tsunami inundation. Different source mechanisms were tested: earthquakes, underwater explosions, caldera collapse, and pyroclastic flows. The most probable source of the 1650 AD Kolumbo tsunami is a 250 m high water surface displacement generated by underwater explosion with an energy of 2 × 1016 J at water depths between 20 and 150 m. The tsunamigenic explosion(s) occurred on September 29, 1650 during the transition between submarine and subaerial phases of the eruption. Caldera subsidence is not an efficient tsunami source mechanism as short (and probably unrealistic) collapse durations (< 5 min) are needed. Pyroclastic flows cannot be discarded, but the required flux (106 to 107 m3 · s- 1) is exceptionally high compared to the magnitude of the eruption.

  7. Source of the tsunami generated by the 1650 AD eruption of Kolumbo submarine volcano (Aegean Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Ulvrova, Martina; Paris, Raphael; Nomikou, Paraskevi; Tappin, Dave

    2016-04-01

    The 1650 AD explosive eruption of Kolumbo submarine volcano (Aegean Sea, Greece) generated a destructive tsunami. In this paper we propose a source mechanism of this poorly documented tsunami using both geological investigations and numerical simulations. Sedimentary evidences of the 1650 AD tsunami were found along the coast of Santorini Island at maximum altitudes ranging between 3.5 m a.s.l. (Perissa, southern coast) and 20 m a.s.l. (Monolithos, eastern coast), corresponding to a minimum inundation of 360 and 630 m respectively. Tsunami deposits correspond to an irregular 5 to 30 cm thick layer of dark grey sand intercalated in soil at depths between 30 and 50 cm. Composition of the tsunami sand is similar to the composition of the present-day beach and clearly differs from the pumiceous gravelly soil. Spatial distribution of the tsunami deposits was confronted to available historical records and to the results of numerical simulations of tsunami inundation. Different scenarios of source mechanism were tested: earthquakes, underwater explosions, caldera collapse, and pyroclastic flows. The most probable source of the 1650 AD Kolumbo tsunami is a 250 m high water surface displacement generated by underwater explosion with an energy of ~2 E15 J at water depths between 20 and 150 m. The tsunamigenic explosion(s) occurred on September 29, 1650 during the transition between submarine and subaerial phases. Caldera subsidence is not an efficient source of tsunami, as short (and probably unrealistic) collapse durations (< 5 minutes) are needed. Pyroclastic flows cannot be discarded, but the required flux (E6 to E7 m³.s-1) is exceptionally high compared to the magnitude of the eruption.

  8. Magnetic mapping of submarine hydrothermal systems at Marsili and Palinuro volcanoes from deep-towed magnetometer data

    NASA Astrophysics Data System (ADS)

    Caratori Tontini, F.; Bortoluzzi, G.; Carmisciano, C.; Cocchi, L.; de Ronde, C. E.; Ligi, M.; Muccini, F.

    2013-12-01

    We collected near-bottom magnetic data at Marsili and Palinuro volcanoes in the Southern Tyrrhenian Sea, by adding a magnetometer to a deep-towed sidescan sonar. Equivalent magnetization maps obtained by inversion of the recorded magnetic anomalies are analyzed to map alteration zones related to hydrothermal processes and are correlated with water-column and seafloor observations of hydrothermal activity. At Marsili volcano, we found a large elliptical area of low magnetization, confirming the existence of a large hydrothermal system located in proximity of the top cone, above the magma chamber. Palinuro volcano is characterized by hydrothermal venting located along the caldera walls, where the corresponding ring faults may provide preferred pathways for the upflow of the hydrothermal fluids.

  9. U-series disequilibrium of basaltic rocks from Kick'em-Jenny submarine volcano, Lesser Antilles island arc

    NASA Astrophysics Data System (ADS)

    Huang, F.; Lundstrom, C. C.

    2005-12-01

    Kick'em Jenny (KEJ) submarine volcano located 9 km to the north of Grenada in the Lesser Antilles volcanic arc produces lavas ranging in composition from high MgO basalts to moderately evolved andesites. We have determined U-series disequilibria in 12 porphyritic lavas erupted from KEJ volcano by TIMS and MC-ICP-MS methods to constrain the timing and identify the processes creating the magma diversity observed. The SiO2 contents of samples studied here vary from 47 to 55 wt.% SiO2 while REE patterns evolve from slightly LREE enriched, MREE/HREE = 1 patterns to strongly LREE enriched, MREE depleted concave-up patterns. Separate dissolutions of sample KEJ100 indicate an external reproducibility (1s) of 0.7% for (230Th/238U) (n=4), 0.8% for (230Th/232Th) (n=4) and 0.6% for (226Ra/230Th) (n=3), respectively. For all sample, (234U/238U) lies within 0.7% of unity, suggesting that secondary alteration by seawater has not disturbed the U-series data significantly. Sample ages for these submarine erupted samples are unknown, resulting in uncertain values for initial (226Ra/230Th); however, 10 out of 12 of the measured (226Ra/230Th) range between 3.16 and 1.13 and are thus unequivocally young with respect to decay of 230Th and 231Pa since eruption. The U (0.535 - 4.876 ppm) and Th (1.25 - 10.78 ppm) concentrations increase with SiO2 contents. (230Th/232Th) has a restricted range, varying from 0.994 to 1.093 with the exception of one sample. (230Th/238U) ranges from 0.684 to 0.875 while (231Pa/235U) ranges from 1.76 up to 2.84, among the highest 231Pa excess in island arcs yet reported. These data confirm previous observations of the unusual behavior of KEJ lavas relative to global observations in having both large 238U and 231Pa excesses. Combined with (226Ra/230Th), these disequilibria observations require that 238U excesses reflect more than solely fluid addition to the mantle wedge from the subducted oceanic slab.

  10. SeaMARC 2 side-scan images of submarine volcanoes: Potential analogues for Venus

    NASA Technical Reports Server (NTRS)

    Fryer, P.; Hussong, D.; Mouginis-Mark, P. J.

    1984-01-01

    The Earth's surface beneath the oceans may be very similar, in terms of ambient pressures, to the surface of Venus. For that reason it is particularly important for geologists studying the surface of Venus to understand the processes which form features on the floors of the oceans. With the SeaMARC 2 seafloor mapping system, it is possible to view a swath of seafloor that is 10 km wide (about 6.2 mi). Side scan images of the Mariana region show that volcanoes of the island arc are more complicated than previously realized and that features of the fore-arc region, which resemble volcanoes morphologically, may result from processes other than volcanism. By comparing data obtained from the ocean floor with radar images of Venus, the geological evolution of that planet may be more fully understood.

  11. Hydrothermal venting and mineralization in the crater of Kick'em Jenny submarine volcano, Grenada (Lesser Antilles)

    NASA Astrophysics Data System (ADS)

    Carey, Steven; Olsen, Rene; Bell, Katherine L. C.; Ballard, Robert; Dondin, Frederic; Roman, Chris; Smart, Clara; Lilley, Marvin; Lupton, John; Seibel, Brad; Cornell, Winton; Moyer, Craig

    2016-03-01

    Kick'em Jenny is a frequently erupting, shallow submarine volcano located 7.5 km off the northern coast of Grenada in the Lesser Antilles subduction zone. Focused and diffuse hydrothermal venting is taking place mainly within a small (˜70 × 110 m) depression within the 300 m diameter crater of the volcano at depths of about 265 m. Much of the crater is blanketed with a layer of fine-grained tephra that has undergone hydrothermal alteration. Clear fluids and gas are being discharged near the center of the depression from mound-like vents at a maximum temperature of 180°C. The gas consists of 93-96% CO2 with trace amounts of methane and hydrogen. Gas flux measurements of individual bubble streams range from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5-35°C above ambient occurs throughout the depression and over large areas of the main crater. These zones are colonized by reddish-yellow bacteria with the production of Fe-oxyhydroxides as surface coatings, fragile spires up to several meters in height, and elongated mounds up to tens of centimeters thick. A high-resolution photomosaic of the inner crater depression shows fluid flow patterns descending the sides of the depression toward the crater floor. We suggest that the negatively buoyant fluid flow is the result of phase separation of hydrothermal fluids at Kick'em Jenny generating a dense saline component that does not rise despite its elevated temperature.

  12. Ultra-long-range hydroacoustic observations of submarine volcanic activity at Monowai, Kermadec Arc

    NASA Astrophysics Data System (ADS)

    Metz, D.; Watts, A. B.; Grevemeyer, I.; Rodgers, M.; Paulatto, M.

    2016-02-01

    Monowai is an active submarine volcanic center in the Kermadec Arc, Southwest Pacific Ocean. During May 2011, it erupted over a period of 5 days, with explosive activity directly linked to the generation of seismoacoustic T phases. We show, using cross-correlation and time-difference-of-arrival techniques, that the eruption is detected as far as Ascension Island, equatorial South Atlantic Ocean, where a bottom moored hydrophone array is operated as part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization. Hydroacoustic phases from the volcanic center must therefore have propagated through the Sound Fixing and Ranging channel in the South Pacific and South Atlantic Oceans, a source-receiver distance of ~15,800 km. We believe this to be the furthest documented range of a naturally occurring underwater signal above 1 Hz. Our findings, which are consistent with observations at regional broadband stations and long-range, acoustic parabolic equation modeling, have implications for submarine volcano monitoring.

  13. Molecular Comparison of Bacterial Communities within Iron-Containing Flocculent Mats Associated with Submarine Volcanoes along the Kermadec Arc▿

    PubMed Central

    Hodges, Tyler W.; Olson, Julie B.

    2009-01-01

    Iron oxide sheaths and filaments are commonly found in hydrothermal environments and have been shown to have a biogenic origin. These structures were seen in the flocculent material associated with two submarine volcanoes along the Kermadec Arc north of New Zealand. Molecular characterization of the bacterial communities associated with the flocculent samples indicated that no known Fe-oxidizing bacteria dominated the recovered clone libraries. However, clones related to the recently described Fe-oxidizing bacterium Mariprofundus ferrooxydans were obtained from both the iron-containing flocculent (Fe-floc) and sediment samples, and peaks corresponding to Mariprofundus ferrooxydans, as well as the related clones, were observed in several of our terminal restriction fragment length polymorphism profiles. A large group of epsilonproteobacterial sequences, for which there is no cultured representative, dominated clones from the Fe-floc libraries and were less prevalent in the sediment sample. Phylogenetic analyses indicated that several operational taxonomic units appeared to be site specific, and statistical analyses of the clone libraries found that all samples were significantly different from each other. Thus, the bacterial communities in the Fe-floc samples were not more closely related to each other than to the sediment communities. PMID:19114513

  14. Molecular comparison of bacterial communities within iron-containing flocculent mats associated with submarine volcanoes along the Kermadec Arc.

    PubMed

    Hodges, Tyler W; Olson, Julie B

    2009-03-01

    Iron oxide sheaths and filaments are commonly found in hydrothermal environments and have been shown to have a biogenic origin. These structures were seen in the flocculent material associated with two submarine volcanoes along the Kermadec Arc north of New Zealand. Molecular characterization of the bacterial communities associated with the flocculent samples indicated that no known Fe-oxidizing bacteria dominated the recovered clone libraries. However, clones related to the recently described Fe-oxidizing bacterium Mariprofundus ferrooxydans were obtained from both the iron-containing flocculent (Fe-floc) and sediment samples, and peaks corresponding to Mariprofundus ferrooxydans, as well as the related clones, were observed in several of our terminal restriction fragment length polymorphism profiles. A large group of epsilonproteobacterial sequences, for which there is no cultured representative, dominated clones from the Fe-floc libraries and were less prevalent in the sediment sample. Phylogenetic analyses indicated that several operational taxonomic units appeared to be site specific, and statistical analyses of the clone libraries found that all samples were significantly different from each other. Thus, the bacterial communities in the Fe-floc samples were not more closely related to each other than to the sediment communities.

  15. Lava bubble-wall fragments formed by submarine hydrovolcanic explosions on Lo'ihi Seamount and Kilauea Volcano

    USGS Publications Warehouse

    Clague, D.A.; Davis, A.S.; Bischoff, J.L.; Dixon, J.E.; Geyer, R.

    2000-01-01

    Glassy bubble-wall fragments, morphologically similar to littoral limu o Pele, have been found in volcanic sands erupted on Lo'ihi Seamount and along the submarine east rift zone of Kilauea Volcano. The limu o Pele fragments are undegassed with respect to H2O and S and formed by mild steam explosions. Angular glass sand fragments apparently form at similar, and greater, depths by cooling-contraction granulation. The limu o Pele fragments from Lo'ihi Seamount are dominantly tholeiitic basalt containing 6.25-7.25% MgO. None of the limu o Pele samples from Lo'ihi Seamount contains less than 5.57% MgO, suggesting that higher viscosity magmas do not form lava bubbles. The dissolved CO2 and H2O contents of 7 of the limu o Pele fragments indicate eruption at 1200??300 m depth (120??30 bar). These pressures exceed that generally thought to limit steam explosions. We conclude that hydrovolcanic eruptions are possible, with appropriate pre-mixing conditions, at pressures as great as 120 bar.

  16. Volcanoes

    ERIC Educational Resources Information Center

    Kunar, L. N. S.

    1975-01-01

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

  17. Volcanoes

    SciTech Connect

    Decker, R.W.; Decker, B.

    1989-01-01

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

  18. Degassing Processes at Persistently Active Explosive Volcanoes

    NASA Astrophysics Data System (ADS)

    Smekens, Jean-Francois

    Among volcanic gases, sulfur dioxide (SO2) is by far the most commonly measured. More than a monitoring proxy for volcanic degassing, SO 2 has the potential to alter climate patterns. Persistently active explosive volcanoes are characterized by short explosive bursts, which often occur at periodic intervals numerous times per day, spanning years to decades. SO 2 emissions at those volcanoes are poorly constrained, in large part because the current satellite monitoring techniques are unable to detect or quantify plumes of low concentration in the troposphere. Eruption plumes also often show high concentrations of ash and/or aerosols, which further inhibit the detection methods. In this work I focus on quantifying volcanic gas emissions at persistently active explosive volcanoes and their variations over short timescales (minutes to hours), in order to document their contribution to natural SO2 flux as well as investigate the physical processes that control their behavior. In order to make these measurements, I first develop and assemble a UV ground-based instrument, and validate it against an independently measured source of SO2 at a coal-burning power plant in Arizona. I establish a measurement protocol and demonstrate that the instrument measures SO 2 fluxes with < 20 % error. Using the same protocol, I establish a record of the degassing patterns at Semeru volcano (Indonesia), a volcano that has been producing cycles of repeated explosions with periods of minutes to hours for the past several decades. Semeru produces an average of 21-71 tons of SO2 per day, amounting to a yearly output of 8-26 Mt. Using the Semeru data, along with a 1-D transient numerical model of magma ascent, I test the validity of a model in which a viscous plug at the top of the conduit produces cycles of eruption and gas release. I find that it can be a valid hypothesis to explain the observed patterns of degassing at Semeru. Periodic behavior in such a system occurs for a very narrow range

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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.

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

    PubMed Central

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

    2017-01-01

    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. PMID:28218270

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

    SciTech Connect

    Gisler, Galen R.; Weaver, R. P.; Mader, Charles L.; Gittings, M. 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.

  3. Living on Active Volcanoes - The Island of Hawai'i

    USGS Publications Warehouse

    Heliker, Christina; Stauffer, Peter H.; Hendley, James W.

    1997-01-01

    People on the Island of Hawai'i face many hazards that come with living on or near active volcanoes. These include lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and tsunamis (giant seawaves). As the population of the island grows, the task of reducing the risk from volcano hazards becomes increasingly difficult. To help protect lives and property, U.S. Geological Survey (USGS) scientists at the Hawaiian Volcano Observatory closely monitor and study Hawai'i's volcanoes and issue timely warnings of hazardous activity.

  4. Crustal structure of the southern Okinawa Trough: Symmetrical rifting, submarine volcano, and potential mantle accretion in the continental back-arc basin

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Back-arc basins are a primary target to understand lithospheric evolution in extension associated with plate subduction. Most of the currently active back-arc basins formed in intraoceanic settings and host well-developed spreading centers where seafloor spreading has occurred. However, rift structure at its initial stage, a key to understand how the continental lithosphere starts to break in a magma-rich back-arc setting, is poorly documented. Here we present seismological evidence for structure of the southern Okinawa Trough, an active rift zone behind the Ryukyu subduction zone. We find that the southern Okinawa Trough exhibits an almost symmetric rift system across the rift axis (Yaeyama Rift) and that the sedimentary layers are highly cut by inward dipping normal faults. The rift structure also accompanies a narrow (2-7 km wide) on-axis intrusion resulted from passive upwelling of magma. On the other hand, an active submarine volcano is located 10 km away from the rift axis. The P wave velocity (Vp) model derived from seismic refraction data suggests that the crust has been significantly thinned from the original 25 km thick arc crust and the thinnest part with 12 km thickness occurs directly beneath the rift axis. The velocity model also reveals that there exists a thick layer with Vp of 6.5-7.2 km/s at lower crustal levels and may indicate that mantle materials accreted at the bottom of the crust during the crustal stretching. The abrupt crustal thinning and the velocity-depth profile suggest that the southern Okinawa Trough is at a transitional stage from continental rifting to seafloor spreading.

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

    PubMed

    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.

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

    PubMed

    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.

  7. The Submarine Volcano Eruption off El Hierro Island: Effects on the Scattering Migrant Biota and the Evolution of the Pelagic Communities

    PubMed Central

    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. PMID:25047077

  8. GlobVolcano: Earth Observation Services for global monitoring of active volcanoes

    NASA Astrophysics Data System (ADS)

    Tampellini, L.; Ratti, R.; Borgström, S.; Seifert, F. M.; Solaro, G.

    2009-04-01

    The GlobVolcano project is part of the Data User Element (DUE) programme of the European Space Agency (ESA). The objective of the project is to demonstrate EO-based (Earth Observation) services able to support the Volcanological Observatories and other mandate users (Civil Protection, scientific communities of volcanoes) in their monitoring activities. The information service is assessed in close cooperation with the user organizations for different types of active volcano, from various geographical areas in various climatic zones. Users are directly and actively involved in the validation of the Earth Observation products, by comparing them with ground data available at each site. The following EO-based information services have been defined, harmonising the user requirements provided by a worldwide selection of user organizations. - Deformation Mapping - Surface Thermal Anomalies - Volcanic Gas Emission (SO2) - Volcanic Ash Tracking During the first phase of the project (completed in June 2008) a pre-operational information system has been designed, implemented and validated, involving a limited number of test areas and respective user organizations (i.e. Piton de la Fournaise in La Reunion Island, Karthala in Comore Islands, Stromboli, Volcano and Etna in Italy, Soufrière Hills in Montserrat Island, Colima in Mexico, Merapi in Indonesia). The second phase of the project (currently on-going) concerns the service provision on pre-operational basis. Fifteen volcanic sites located in four continents are regularly monitored and as many user organizations are involved and cooperating with the project team. Based on user requirements, the GlobVolcano Information System has been developed following system engineering rules and criteria, besides most recent interoperability standards for geospatial data. The GlobVolcano Information System includes two main elements: 1. The GlobVolcano Data Processing System, which consists of seven of EO data processing subsystems

  9. July 1973 ground survey of active Central American volcanoes

    NASA Technical Reports Server (NTRS)

    Stoiber, R. E. (Principal Investigator); Rose, W. I., Jr.

    1973-01-01

    The author has identified the following significant results. Ground survey has shown that thermal anomalies of various sizes associated with volcanic activity at several Central American volcanoes should be detectable from Skylab. Anomalously hot areas of especially large size (greater than 500 m in diameter) are now found at Santiaguito and Pacaya volcanoes in Guatemala and San Cristobal in Nicaragua. Smaller anomalous areas are to be found at least seven other volcanoes. This report is completed after ground survey of eleven volcanoes and ground-based radiation thermometry mapping at these same points.

  10. The changing shapes of active volcanoes: History, evolution, and future challenges for volcano geodesy

    USGS Publications Warehouse

    Poland, Michael P.; Hamburger, Michael W.; Newman, Andrew V.

    2006-01-01

    At the very heart of volcanology lies the search for the 'plumbing systems' that form the inner workings of Earth’s active volcanoes. By their very nature, however, the magmatic reservoirs and conduits that underlie these active volcanic systems are elusive; mostly they are observable only through circumstantial evidence, using indirect, and often ambiguous, surficial measurements. Of course, we can infer much about these systems from geologic investigation of materials brought to the surface by eruptions and of the exposed roots of ancient volcanoes. But how can we study the magmatic processes that are occurring beneath Earth’s active volcanoes? What are the geometry, scale, physical, and chemical characteristics of magma reservoirs? Can we infer the dynamics of magma transport? Can we use this information to better forecast the future behavior of volcanoes? These questions comprise some of the most fundamental, recurring themes of modern research in volcanology. The field of volcano geodesy is uniquely situated to provide critical observational constraints on these problems. For the past decade, armed with a new array of technological innovations, equipped with powerful computers, and prepared with new analytical tools, volcano geodesists have been poised to make significant advances in our fundamental understanding of the behavior of active volcanic systems. The purpose of this volume is to highlight some of these recent advances, particularly in the collection and interpretation of geodetic data from actively deforming volcanoes. The 18 papers that follow report on new geodetic data that offer valuable insights into eruptive activity and magma transport; they present new models and modeling strategies that have the potential to greatly increase understanding of magmatic, hydrothermal, and volcano-tectonic processes; and they describe innovative techniques for collecting geodetic measurements from remote, poorly accessible, or hazardous volcanoes. To provide

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

    USGS Publications Warehouse

    Schilling, Steve P.

    1996-01-01

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

  12. Global data collection and the surveillance of active volcanoes

    USGS Publications Warehouse

    Ward, P.L.

    1990-01-01

    Data relay systems on existing earth-orbiting satellites provide an inexpensive way to collect environmental data from numerous remote sites around the world. This technology could be used effectively for fundamental monitoring of most of the world's active volcanoes. Such global monitoring would focus attention on the most dangerous volcanoes that are likely to significantly impact the geosphere and the biosphere. ?? 1990.

  13. Special issue: The changing shapes of active volcanoes: Recent results and advances in volcano geodesy

    USGS Publications Warehouse

    Poland, Michael P.; Newman, Andrew V.

    2006-01-01

    The 18 papers herein report on new geodetic data that offer valuable insights into eruptive activity and magma transport; they present new models and modeling strategies that have the potential to greatly increase understanding of magmatic, hydrothermal, and volcano-tectonic processes; and they describe innovative techniques for collecting geodetic measurements from remote, poorly accessible, or hazardous volcanoes. To provide a proper context for these studies, we offer a short review of the evolution of volcano geodesy, as well as a case study that highlights recent advances in the field by comparing the geodetic response to recent eruptive episodes at Mount St. Helens. Finally, we point out a few areas that continue to challenge the volcano geodesy community, some of which are addressed by the papers that follow and which undoubtedly will be the focus of future research for years to come.

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

    NASA Astrophysics Data System (ADS)

    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

  15. Volcanoes

    MedlinePlus

    ... hot gases and debris called pyroclastic flows. Some dangers from volcanoes can be predicted ahead of time ... for All Disasters Illnesses, injuries, carbon monoxide poisoning, animals & insects, food, water, cleanup, mold, environmental concerns, and ...

  16. Volcanoes

    USGS Publications Warehouse

    Tilling, Robert I.

    1998-01-01

    Volcanoes destroy and volcanoes create. The catastrophic eruption of Mount St. Helens on May 18, 1980, made clear the awesome destructive power of a volcano. Yet, over a time span longer than human memory and record, volcanoes have played a key role in forming and modifying the planet upon which we live. More than 80 percent of the Earth's surface--above and below sea level--is of volcanic origin. Gaseous emissions from volcanic vents over hundreds of millions of years formed the Earth's earliest oceans and atmosphere, which supplied the ingredients vital to evolve and sustain life. Over geologic eons, countless volcanic eruptions have produced mountains, plateaus, and plains, which subsequent erosion and weathering have sculpted into majestic landscapes and formed fertile soils.

  17. Seismic activity of Erebus volcano, antarctica

    NASA Astrophysics Data System (ADS)

    Kaminuma, Katsutada

    1987-11-01

    Mount Erebus is presently the only Antarctic volcano with sustained eruptive activity in the past few years. It is located on Ross Island and a convecting anorthoclase phonolite lava lake has occupied the summit crater of Mount Erebus from January 1973 to September 1984. A program to monitor the seismic activity of Mount Erebus named IMESS was started in December 1980 as an international cooperative program among Japan, the United States and New Zealand. A new volcanic episode began on 13 September, 1984 and continued until December. Our main observations from the seismic activity from 1982 1985 are as follows: (1) The average numbers of earthquakes which occurred around Mount Erebus in 1982, 1983 and January August 1984 were 64, 134 and 146 events per day, respectively. Several earthquake swarms occurred each year. (2) The averag number of earthquakes in 1985 is 23 events per day, with only one earthquake swarm. (3) A remarkable decrease of the background seismicity is recognized before and after the September 1984 activity. (4) Only a few earthquakes were located in the area surrounding Erebus mountain after the September 1984 activity. A magma reservoir is estimated to be located in the southwest area beneath the Erebus summit, based on the hypocenter distributions of earthquakes.

  18. Active submarine volcanism on the Society hotspot swell (west Pacific): A geochemical study

    SciTech Connect

    Devey, C.W.; Albarede, F.; Michard, A. ); Cheminee, J.L. ); Muehe, R.; Stoffers, P. )

    1990-04-10

    The present work deals with the petrography and geochemistry of lavas dredged from five active submarine volcanoes (named Mehetia, Moua Pihaa, Rocard, Teahitia, and Cyana) from the southeast end of the Society Islands hotspot trace. Most samples are basic and alkaline. Fractionation modelling based on major and minor compatible element variations suggests that olivine and minor clinopyroxene were the major fractionating phases. Rocard and Cyana have yielded more evolved, trachy-phonolitic, glassy samples. Both basaltic and phonolitic samples are incompatible-element enriched. The trachy-phonolite patterns show middle (REE) depletion and negative Eu anomalies. The Moua Pihaa basalts have flatter patterns than the other basalts. All smaples, with the exception of a sample from Moua Pihaa which has elevated {sup 206}Pb/{sup 204}Pb, fall on linear Sr-Nd-Pb isotopic arrays, suggesting two end-member mixing. The Sr isotopic variations in the samples excluding Moua Pihaa correlate positively with Rb/Nb, Pb/Ce, and SiO{sub 2} variations, idicating a component of mantle enriched by injection of material from a subducted oceanic slab. Correlation of {sup 207}Pb/{sup 204}Pb with {sup 87}Sr/{sup 86}Sr suggests that the subducted material is geochemically old. The absence of a MORB component in the Society magmatism, the small volumes of the Polynesian hotspot volcanoes, and the lack of more intense volcanic activity near the center of the Pacific Superswell, all lead to the conclusion that the latter is unlikely to be caused by a large convective plume.

  19. Shrimp Populations on Northwest Rota, an Active Volcano of the Mariana Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Tunnicliffe, V.; Juniper, S. K.; Limén, H.; Jones, W. J.; Vrijenhoek, R.; Webber, R.; Eerkes-Medrano, D.

    2004-12-01

    NW Rota-1 is a submarine volcano that manifested active volcanic and hydrothermal activity during submersible surveys in March 2004 (see Embley et al.). Substratum on the volcano summit (520 m depth) was entirely basalt outcrop or variously-sized ejecta lying near the angle of repose. While no fauna inhabited the rim of the volcanic pit, patches of shrimp were located within 25 m and on the nearby summit. Two species are present. Opaepele cf. loihi shows few morphological differences from either a nearby population on Eifuku Volcano (see Chadwick et al.) at 1700 m depth or from the type locality in Hawaii. A molecular comparison of COI sequences of 13 specimens found little difference from two Hawaiian sequences. Video observations detail frequent feeding activity using spatulate chelipeds to trim microbial filaments as the cephalothorax sways across the substratum. The second species is an undescribed Alvinocaris. Juveniles of this species appear to form clusters distinct from Opaepele where they also graze on filaments. Sparse adults of Alvinocaris range up to 5.5 cm long and display aggressive behaviour moving through patches of smaller shrimp. Densities of Opaepele were highest on sloping rock walls (over 500 per sq.m.) whereas adult Alvinocaris were more abundant on rubble. This division may reflect food preference: microbial filaments versus polychaetes and meiofauna. Characterization of particulates from these substrata was conducted using visual sorting and stable isotope composition. As Alvinocaris matures, the chelipeds enlarge, enabling a greater predatory capacity. Measurements of Opaepele from digital in situ images reveal a population structure suggesting a recent recruitment. Average size is significantly smaller than the Eifuku population and no egg-bearing females were collected. The disjunct range of this species where it occurs on active volcanoes 6000 km apart is puzzling. Further work on intermediate sites and into the reproductive strategy of

  20. An authoritative global database for active submarine hydrothermal vent fields

    NASA Astrophysics Data System (ADS)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.; Maffei, Andrew

    2013-11-01

    The InterRidge Vents Database is available online as the authoritative reference for locations of active submarine hydrothermal vent fields. Here we describe the revision of the database to an open source content management system and conduct a meta-analysis of the global distribution of known active vent fields. The number of known active vent fields has almost doubled in the past decade (521 as of year 2009), with about half visually confirmed and others inferred active from physical and chemical clues. Although previously known mainly from mid-ocean ridges (MORs), active vent fields at MORs now comprise only half of the total known, with about a quarter each now known at volcanic arcs and back-arc spreading centers. Discoveries in arc and back-arc settings resulted in an increase in known vent fields within exclusive economic zones, consequently reducing the proportion known in high seas to one third. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. The purpose of the database now extends beyond academic research and education and into marine policy and management, with at least 18% of known vent fields in areas granted or pending applications for mineral prospecting and 8% in marine protected areas.

  1. Using IMS hydrophone data for detecting submarine volcanic activity: Insights from Monowai, 26°S Kermadec Arc

    NASA Astrophysics Data System (ADS)

    Metz, Dirk; Watts, Anthony B.; Grevemeyer, Ingo; Rodgers, Mel; Paulatto, Michele

    2016-04-01

    Only little is known on active volcanism in the ocean. As eruptions are attenuated by seawater and fallout does not regularly reach the sea surface, eruption rates and mechanisms are poorly understood. Estimations on the number of active volcanoes across the modern seas range from hundreds to thousands, but only very few active sites are known. Monowai is a submarine volcanic centre in the northern Kermadec Arc, Southwest Pacific Ocean. During May 2011, it erupted over a period of five days, with explosive activity directly linked to the generation of seismoacoustic tertiary waves ('T-phases'), recorded at three broadband seismic stations in the region. We show, using windowed cross-correlation and time-difference-of-arrival techniques, that T-phases associated with this eruption are detected as far as Ascension Island, South Atlantic Ocean, where two bottom-moored hydrophone arrays are operated as part of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). We observe a high incidence of T-phase arrivals during the time of the eruption, with the angle of arrival stabilizing at the geodesic azimuth between the IMS arrays and Monowai. T-phases from the volcanic centre must therefore have propagated through the Sound Fixing And Ranging (SOFAR) channel in the South Pacific and South Atlantic Oceans and over a total geodesic range of approximately 15,800 km, one of the longest source-receiver distances of any naturally occurring underwater signal ever observed. Our findings, which are consistent with observations at regional broadband stations and two dimensional, long-range, parabolic equation modelling, highlight the exceptional capabilities of the hydroacoustic waveform component of the IMS for remotely detecting episodes of submarine volcanic activity. Using Monowai and the hydrophone arrays at Ascension Island as a natural laboratory, we investigate the long-term eruptive record of a submarine volcano from

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

    NASA Astrophysics Data System (ADS)

    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

  3. Measuring thermal budgets of active volcanoes by satellite remote sensing

    NASA Technical Reports Server (NTRS)

    Glaze, L.; Francis, P. W.; Rothery, D. A.

    1989-01-01

    Thematic Mapper measurements of the total radiant energy flux Q at Lascar volcano in north Chile for December 1984 are reported. The results are consistent with the earlier suggestion that a lava lake is the source of a reported thermal budget anomaly, and with values for 1985-1986 that are much lower, suggesting that fumarolic activity was then a more likely heat source. The results show that satellite remote sensing may be used to monitor the activity of a volcano quantitatively, in a way not possible by conventional ground studies, and may provide a method for predicting eruptions.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Hawaii's volcanoes revealed

    USGS Publications Warehouse

    Eakins, Barry W.; Robinson, Joel E.; Kanamatsu, Toshiya; Naka, Jiro; Smith, John R.; Takahashi, Eiichi; Clague, David A.

    2003-01-01

    Hawaiian volcanoes typically evolve in four stages as volcanism waxes and wanes: (1) early alkalic, when volcanism originates on the deep sea floor; (2) shield, when roughly 95 percent of a volcano's volume is emplaced; (3) post-shield alkalic, when small-volume eruptions build scattered cones that thinly cap the shield-stage lavas; and (4) rejuvenated, when lavas of distinct chemistry erupt following a lengthy period of erosion and volcanic quiescence. During the early alkalic and shield stages, two or more elongate rift zones may develop as flanks of the volcano separate. Mantle-derived magma rises through a vertical conduit and is temporarily stored in a shallow summit reservoir from which magma may erupt within the summit region or be injected laterally into the rift zones. The ongoing activity at Kilauea's Pu?u ?O?o cone that began in January 1983 is one such rift-zone eruption. The rift zones commonly extend deep underwater, producing submarine eruptions of bulbous pillow lava. Once a volcano has grown above sea level, subaerial eruptions produce lava flows of jagged, clinkery ?a?a or smooth, ropy pahoehoe. If the flows reach the ocean they are rapidly quenched by seawater and shatter, producing a steep blanket of unstable volcanic sediment that mantles the upper submarine slopes. Above sea level then, the volcanoes develop the classic shield profile of gentle lava-flow slopes, whereas below sea level slopes are substantially steeper. While the volcanoes grow rapidly during the shield stage, they may also collapse catastrophically, generating giant landslides and tsunami, or fail more gradually, forming slumps. Deformation and seismicity along Kilauea's south flank indicate that slumping is occurring there today. Loading of the underlying Pacific Plate by the growing volcanic edifices causes subsidence, forming deep basins at the base of the volcanoes. Once volcanism wanes and lava flows no longer reach the ocean, the volcano continues to submerge, while

  6. Linking petrology and seismology at an active volcano.

    PubMed

    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.

  7. Output rate of magma from active central volcanoes

    NASA Technical Reports Server (NTRS)

    Wadge, G.

    1980-01-01

    For part of their historic records, nine of the most active volcanoes on earth have each erupted magma at a nearly constant rate. These output rates are very similar and range from 0.69 to 0.26 cu m/s. The volcanoes discussed - Kilauea, Mauna Loa, Fuego, Santiaguito, Nyamuragira, Hekla, Piton de la Fournaise, Vesuvius and Etna - represent almost the whole spectrum of plate tectonic settings of volcanism. A common mechanism of buoyantly rising magma-filled cracks in the upper crust may contribute to the observed restricted range of the rates of output.

  8. Reconstructing Final H2O Contents of Hydrated Rhyolitic Glasses: Insights into H2O Degassing and Eruptive Style of Silicic Submarine Volcanoes

    NASA Astrophysics Data System (ADS)

    McIntosh, I. M.; Nichols, A. R.; Tani, K.; Llewellin, E. W.

    2015-12-01

    H2O degassing influences the evolution of magma viscosity and vesicularity during ascent through the crust, and ultimately the eruptive style. Investigating H2O degassing requires data on both initial and final H2O contents. Initial H2O contents are revealed by melt inclusion data, while final H2O contents are found from dissolved H2O contents of volcanic glass. However volcanic glasses, particularly of silicic composition, are susceptible to secondary hydration i.e. the addition of H2O from the surrounding environment at ambient temperature during the time following pyroclast deposition. Obtaining meaningful final H2O data therefore requires distinguishing between the original final dissolved H2O content and the H2O added subsequently during hydration. Since H2O added during hydration is added as molecular H2O (H2Om), and the species interconversion between H2Om and hydroxyl (OH) species is negligible at ambient temperature, the final OH content of the glass remains unaltered during hydration. By using H2O speciation models to find the original H2Om content that would correspond to the measured OH content of the glass, the original total H2O (H2Ot) content of the glass prior to hydration can be reconstructed. These H2O speciation data are obtained using FTIR spectroscopy. In many cases, particularly where vesicular glasses necessitate thin wafers, OH cannot be measured directly and instead is calculated indirectly as OH = H2Ot - H2Om. Here we demonstrate the importance of using a speciation-dependent H2Ot molar absorptivity coefficient to obtain accurate H2Ot and H2O speciation data and outline a methodology for calculating such a coefficient for rhyolite glasses, with application to hydrated silicic pumice from submarine volcanoes in the Japanese Izu-Bonin Arc. Although hydrated pumice from Kurose Nishi and Oomurodashi now contain ~1.0 - 2.5 wt% H2Ot, their pre-hydration final H2O contents were typically ~0.3 - 0.4 wt% H2Ot. Furthermore, we show that pre

  9. Three-dimensional flow dynamics of an active submarine channel

    NASA Astrophysics Data System (ADS)

    Sumner, E. J.; Dorrell, R. M.; Peakall, J.; Darby, S. E.; Parsons, D. R.; Wynn, R.

    2012-12-01

    Field scale submarine channel gravity currents are notoriously difficult to measure and thus directly investigate due to their inaccessible location and infrequent nature, which is compounded by present sea-level high-stand. An exception to this is the almost continuous density-driven current that results from the inflow of saline Mediterranean water, via the Bosporus strait, into the Black Sea. This flow has carved a sinuous channel system in water depths of 70 to 120 m. The relatively shallow depths of the channel and the continuous nature of this current provide a rare opportunity to study three-dimensional flow dynamics and the interaction of the flow with a seafloor channel network. Thus, it provides a rare analogue for channelized dilute sediment-laden turbidity currents. Sediment erosion, transport and deposition within submarine channel bends is primarily controlled by the magnitude and direction of near bed flow. Flow around channel bends is characterized by a helical or spiralling structure. In rivers this helical flow is characterized by near-surface fluid moving toward the outer bank and near-bed fluid moving toward the inner bank. Following fierce debate over the last decade, it is now accepted that helical flow in submarine channel bends can display a variety of complex structures. Most importantly for understanding sediment transport, near bed flow can be directed towards the outer bank, which is in the opposite sense to in a river. The next challenge is to understand what the exact controls on the orientation of helical flow cells within submarine flows are, and their spatial evolution around bends. We present data from the Black Sea showing how the three-dimensional velocity and density of a submarine gravity current evolves at multiple cross sections as the flow travels around a bend. We use this data to calculate the magnitude, relative importance and interaction of centrifugal, coriolis and pressure gradients in controlling the structure of

  10. Seismicity characteristics of a potentially active Quaternary volcano: The Tatun Volcano Group, northern Taiwan

    NASA Astrophysics Data System (ADS)

    Konstantinou, Konstantinos I.; Lin, Cheng-Horng; Liang, Wen-Tzong

    2007-02-01

    The Tatun Volcano Group (TVG) is located at the northern tip of Taiwan, near the capital Taipei and close to two nuclear power plants. Because of lack of any activity in historical times it has been classified as an extinct volcano, even though more recent studies suggest that TVG might have been active during the last 20 ka. In May 2003 a seismic monitoring project at the TVG area was initiated by deploying eight three-component seismic stations some of them equipped with both short-period and broadband sensors. During the 18 months observation period local seismicity mainly consisted of high frequency earthquakes either occurring as isolated events, or as a continuous sequence in the form of spasmodic bursts. Mixed and low frequency events were also present during the same period, even though they occurred only rarely. Arrival times from events with clear P-/S-wave phases were inverted in order to obtain a minimum 1D velocity model with station corrections. Probabilistic nonlinear earthquake locations were calculated for all these events using the newly derived velocity model. Most high frequency seismicity appeared to be concentrated near the areas of hydrothermal activity, forming tight clusters at depths shallower than 4 km. Relative locations, calculated using the double-difference method and utilising catalogue and cross-correlation differential traveltimes, showed insignificant differences when compared to the nonlinear probabilistic locations. In general, seismicity in the TVG area seems to be primarily driven by circulation of hydrothermal fluids as indicated by the occurrence of spasmodic bursts, mixed/low frequency events and a b-value (1.17 ± 0.1) higher than in any other part of Taiwan. These observations, that are similar to those reported in other dormant Quaternary volcanoes, indicate that a magma chamber may still exist beneath TVG and that a future eruption or period of unrest should not be considered unlikely.

  11. GlobVolcano pre-operational services for global monitoring active volcanoes

    NASA Astrophysics Data System (ADS)

    Tampellini, Lucia; Ratti, Raffaella; Borgström, Sven; Seifert, Frank Martin; Peltier, Aline; Kaminski, Edouard; Bianchi, Marco; Branson, Wendy; Ferrucci, Fabrizio; Hirn, Barbara; van der Voet, Paul; van Geffen, J.

    2010-05-01

    The GlobVolcano project (2007-2010) is part of the Data User Element programme of the European Space Agency (ESA). The project aims at demonstrating Earth Observation (EO) based integrated services to support the Volcano Observatories and other mandate users (e.g. Civil Protection) in their monitoring activities. The information services are assessed in close cooperation with the user organizations for different types of volcano, from various geographical areas in various climatic zones. In a first phase, a complete information system has been designed, implemented and validated, involving a limited number of test areas and respective user organizations. In the currently on-going second phase, GlobVolcano is delivering pre-operational services over 15 volcanic sites located in three continents and as many user organizations are involved and cooperating with the project team. The set of GlobVolcano offered EO based information products is composed as follows: Deformation Mapping DInSAR (Differential Synthetic Aperture Radar Interferometry) has been used to study a wide range of surface displacements related to different phenomena (e.g. seismic faults, volcanoes, landslides) at a spatial resolution of less than 100 m and cm-level precision. Permanent Scatterers SAR Interferometry method (PSInSARTM) has been introduced by Politecnico of Milano as an advanced InSAR technique capable of measuring millimetre scale displacements of individual radar targets on the ground by using multi-temporal data-sets, estimating and removing the atmospheric components. Other techniques (e.g. CTM) have followed similar strategies and have shown promising results in different scenarios. Different processing approaches have been adopted, according to data availability, characteristic of the area and dynamic characteristics of the volcano. Conventional DInSAR: Colima (Mexico), Nyiragongo (Congo), Pico (Azores), Areanal (Costa Rica) PSInSARTM: Piton de la Fournaise (La Reunion Island

  12. 2011 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2014-01-01

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

  13. Open-System Magma Reservoir Affects Gas Segregation, Vesiculation, Fragmentation and Lava/Pyroclast Dispersal During the 1.2 km-deep 2007-2010 Submarine Eruption at West Mata Volcano

    NASA Astrophysics Data System (ADS)

    Rubin, K. H.; Clague, D. A.; Embley, R. W.; Hellebrand, E.; Soule, S. A.; Resing, J.

    2014-12-01

    West Mata, a small, active rear-arc volcano in the NE Lau Basin, erupts crystal and gas rich boninite magma. Eruptions were observed at the summit (1.2 km water depth) during 5 ROV Jason dives in 2009 (the deepest erupting submarine volcano observed to date). Subsequent ROV and ship-based bathymetric mapping revealed that a pit crater formed and the summit eruption ceased in 2010, with roughly simultaneous eruptions along the SW rift zone. During the summit eruption, a combination of water depth, H2O-CO2-rich and high crystallinity magma, a split in the conduit to feed two vent sites, and waxing/waning magma supply led to a range of effusive/explosive eruption styles and volcanic deposit types. The 2-3 vent Hades cluster and the lone Prometheus vent had different eruption characteristics. Petrographic, petrologic and geochemical studies of erupted products indicate a change in magma composition in time and space over a period of 3.5 yrs, suggesting a small, open-system magma reservoir within the volcano. Prometheus (1174m depth) produced mostly pyroclastic material during our observations (e.g., highly vesicular glowing fluidal ejecta that cooled in the water column and rounded recycled dense clasts), but sampling and 210Po radiometric dating show that several months prior pillowed lava flows, subsequently covered with cm-sized pyroclasts, had flowed >50m from the vent. In contrast, vents at Hades (1200m depth) cycled between lava production and vigorous degassing, 10-20m high fire fountains and bursts of glowing lava-skinned bubbles, the products of which froze/broke in the water column, forming unstable cones of spatter and scoria near the vents. We hypothesize that bubbles collapse rather than form lava balloons because of skin brittleness (from high crystal content) and hydrostatic pressure. Clast settling times and patterns suggest >100m water column rise height for 10+ cm-sized fragments. Pillow flows were also observed to be issuing from the base of the

  14. Continuous gravity observations at active volcanoes through superconducting gravimeters

    NASA Astrophysics Data System (ADS)

    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.

  15. Deep structure and origin of active volcanoes in China

    NASA Astrophysics Data System (ADS)

    Zhao, D.

    2010-12-01

    Recent geophysical studies have provided important constraints on the deep structure and origin of the active intraplate volcanoes in Mainland China. Magmatism in the western Pacific arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab (e.g., Zhao et al., 2009a), while the intraplate magmatism in China has different origins. The active volcanoes in Northeast China (such as the Changbai and Wudalianchi) are caused by hot upwelling in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well (Zhao et al., 2009b). The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate (or Indian plate) (Lei et al., 2009a). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and Indian slab's deep subduction in the west down to the lower mantle (Lei et al., 2009b; Zhao, 2009). The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions (Zhao, 2009). References Lei, J., D. Zhao, Y. Su, 2009a. Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data. J. Geophys. Res. 114, B05302. Lei, J., D. Zhao, B. Steinberger et al., 2009b. New seismic constraints on the upper mantle structure of the Hainan plume. Phys. Earth Planet. Inter. 173, 33-50. Zhao, D., 2009. Multiscale seismic tomography and mantle dynamics. Gondwana Res. 15, 297-323. Zhao, D., Z. Wang, N. Umino, A. Hasegawa, 2009a. Mapping the mantle wedge and interplate thrust zone of the northeast Japan arc. Tectonophysics 467, 89-106. Zhao, D., Y. Tian, J. Lei, L. Liu, 2009b. Seismic

  16. Rock magnetic and petrographical-mineralogical studies of the dredged rocks from the submarine volcanoes of the Sea-of-Okhotsk slope within the northern part of the Kuril Island Arc

    NASA Astrophysics Data System (ADS)

    Rashidov, V. A.; Pilipenko, O. V.; Petrova, V. V.

    2016-07-01

    The rock magnetic properties of the samples of dredged rocks composing the submarine volcanic edifices within the Sea-of-Okhotsk slope of the northern part of the Kuril Island Arc are studied. The measurements of the standard rock magnetic parameters, thermomagnetic analysis, petrographical studies, and microprobe investigations have been carried out. The magnetization of the studied rocks is mainly carried by the pseudo-single domain and multidomain titanomagnetite and low-Ti titanomagnetite grains. The high values of the natural remanent magnetization are due to the pseudo-single-domain structure of the titanomagnetite grains, whereas the high values of magnetic susceptibility are associated with the high concentration of ferrimagnetic grains. The highest Curie points are observed in the titanomagnetite grains of the igneous rocks composing the edifices of the Smirnov, Edelshtein, and 1.4 submarine volcanoes.

  17. Active Volcano Monitoring using a Space-based Hyperspectral Imager

    NASA Astrophysics Data System (ADS)

    Cipar, J. J.; Dunn, R.; Cooley, T.

    2010-12-01

    Active volcanoes occur on every continent, often in close proximity to heavily populated areas. While ground-based studies are essential for scientific research and disaster mitigation, remote sensing from space can provide rapid and continuous monitoring of active and potentially active volcanoes [Ramsey and Flynn, 2004]. In this paper, we report on hyperspectral measurements of Kilauea volcano, Hawaii. Hyperspectral images obtained by the US Air Force TacSat-3/ARTEMIS sensor [Lockwood et al, 2006] are used to obtain estimates of the surface temperatures for the volcano. ARTEMIS measures surface-reflected light in the visible, near-infrared, and short-wave infrared bands (VNIR-SWIR). The SWIR bands are known to be sensitive to thermal radiation [Green, 1996]. For example, images from the NASA Hyperion hyperspectral sensor have shown the extent of wildfires and active volcanoes [Young, 2009]. We employ the methodology described by Dennison et al, (2006) to obtain an estimate of the temperature of the active region of Kilauea. Both day and night-time images were used in the analysis. To improve the estimate, we aggregated neighboring pixels. The active rim of the lava lake is clearly discernable in the temperature image, with a measured temperature exceeding 1100o C. The temperature decreases markedly on the exterior of the summit crater. While a long-wave infrared (LWIR) sensor would be ideal for volcano monitoring, we have shown that the thermal state of an active volcano can be monitored using the SWIR channels of a reflective hyperspectral imager. References: Dennison, Philip E., Kraivut Charoensiri, Dar A. Roberts, Seth H. Peterson, and Robert O. Green (2006). Wildfire temperature and land cover modeling using hyperspectral data, Remote Sens. Environ., vol. 100, pp. 212-222. Green, R. O. (1996). Estimation of biomass fire temperature and areal extent from calibrated AVIRIS spectra, in Summaries of the 6th Annual JPL Airborne Earth Science Workshop, Pasadena, CA

  18. Crustal deformation and volcanic earthquakes associated with the recent volcanic activity of Iwojima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ueda, H.; Fujita, E.; Tanada, T.

    2013-12-01

    Iwojima is an active volcanic island located within a 10 km wide submarine caldera about 1250 km to the south of Tokyo, Japan. The seismometer and GPS network of National Research Institute for Earth Science and Disaster Prevention (NIED) in Iwojima has observed a repeating island wide uplift more than 1 m associated with large number of volcanic earthquakes every several years. During 2006-2012, we observed more than 20000 volcanic earthquakes and an uplift of about 3 m, and precursory volcanic earthquakes and rapid crustal deformation just before the small submarine eruption near the northern coast of Iwojima in April 2012. In a restless volcano such as Iwojima, it is important issue to distinguish whether rapid crustal deformation and intense earthquake activity lead to an eruption or not. According to a long period geodetic observation by Ukawa et al. (2006), the crustal deformation of Iwojima can be classify into 2 phases. The first is an island wide large uplift centering on Motoyama area (the eastern part of the island, the center of the caldera), and the second is contraction and subsidence at local area centering on Motoyama and uplift around that area. They are interpreted by superposition of crustal deformations by a shallow contraction source and a deep seated inflation source beneath Motoyama. The earthquake activity of Iwojima highly correlates with the island wide large uplift, suggesting the earthquakes are almost controlled by a magma accumulation into a deep seated magma chamber. In contrast to the activity, the precursory activity of the eruption in 2012 is deviated from the correlation. The rapid crustal deformation just before and after the eruption in 2012 can be interpreted by rapid inflation and deflation of a shallow sill source about 1km deep, respectively, suggesting that it was caused by a shallow hydrothermal activity. The result shows that we can probably distinguish an abnormal activity related with a volcanic eruption when we observe

  19. InSAR observations of active volcanoes in Latin America

    NASA Astrophysics Data System (ADS)

    Morales Rivera, A. M.; Chaussard, E.; Amelung, F.

    2012-12-01

    Over the last decade satellite-based interferometric synthetic aperture radar (InSAR) has developed into a well-known technique to gauge the status of active volcanoes. The InSAR technique can detect the ascent of magma to shallow levels of the volcanic plumbing system because new arriving magma pressurizes the system. This is likely associated with the inflation of the volcanic edifice and the surroundings. Although the potential of InSAR to detect magma migration is well known, the principal limitation was that only for few volcanoes frequent observations were acquired. The ALOS-1 satellite of the Japanese Aerospace Exploration Agency (JAXA) acquired a global L-band data set of 15-20 acquisitions during 2006-2011. Here we use ALOS InSAR and Small Baseline (SB) time-series methods for a ground deformation survey of Latin America with emphasis on the northern Andes. We present time-dependent ground deformation data for the volcanoes in Colombia, Ecuador and Peru and interpret the observations in terms of the dynamics of the volcanic systems.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  1. Seismicity and active tectonics at Coloumbo Reef (Aegean Sea, Greece): Monitoring an active volcano at Santorini Volcanic Center using a temporary seismic network

    NASA Astrophysics Data System (ADS)

    Dimitriadis, I.; Karagianni, E.; Panagiotopoulos, D.; Papazachos, C.; Hatzidimitriou, P.; Bohnhoff, M.; Rische, M.; Meier, T.

    2009-02-01

    The volcanic center of Santorini Island is the most active volcano of the southern Aegean volcanic arc. Α dense seismic array consisting of fourteen portable broadband seismological stations has been deployed in order to monitor and study the seismo-volcanic activity at the broader area of the Santorini volcanic center between March 2003 and September 2003. Additional recordings from a neighbouring larger scale temporary network (CYCNET) were also used for the relocation of more than 240 earthquakes recorded by both arrays. A double-difference relocation technique was used, in order to obtain optimal focal parameters for the best-constrained earthquakes. The results indicate that the seismic activity of the Santorini volcanic center is strongly associated with the tectonic regime of the broader Southern Aegean Sea area as well as with the volcanic processes. The main cluster of the epicenters is located at the Coloumbo Reef, a submarine volcano of the volcanic system of Santorini Islands. A smaller cluster of events is located near the Anydros Islet, aligned in a NE-SW direction, running almost along the main tectonic feature of the area under study, the Santorini-Amorgos Fault Zone. In contrast, the main Santorini Island caldera is characterized by the almost complete absence of seismicity. This contrast is in very good agreement with recent volcanological and marine studies, with the Coloumbo volcanic center showing an intense high-temperature hydrothermal activity, in comparison to the corresponding low-level activity of the Santorini caldera. The high-resolution hypocentral relocations present a clear view of the volcanic submarine structure at the Coloumbo Reef, showing that the main seismic activity is located within a very narrow vertical column, mainly at depths between 6 and 9 km. The focal mechanisms of the best-located events show that the cluster at the Coloumbo Reef is associated with the "Kameni-Coloumbo Fracture Zone", which corresponds to the

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

    NASA Astrophysics Data System (ADS)

    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

  3. Study of Seismic Activity at Ceboruco Volcano, Mexico

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Many societies and their economies endure the disastrous consequences of destructive volcanic eruptions. The Ceboruco stratovolcano (2,280 m.a.s.l.) is located in Nayarit, Mexico, at the west of the Mexican volcanic belt and towards the Sierra de San Pedro southeast, which is a key communication point for coast of Jalisco and Nayarit and the northwest of Mexico. It last eruptive activity was in 1875, and during the following five years it presents superficial activity such as vapor emissions, ash falls and riodacitic composition lava flows along the southeast side. Although surface activity has been restricted to fumaroles near the summit, Ceboruco exhibits regular seismic unrest characterized by both low frequency seismic events and volcano-tectonic earthquakes. From March 2003 until July 2008 a three-component short-period seismograph Marslite station with a Lennartz 3D (1Hz) was deployed in the south flank (CEBN) and within 2 km from the summit to monitoring the seismic activity at the volcano. The LF seismicity recorded was classified using waveform characteristics and digital analysis. We obtained four groups: impulsive arrivals, extended coda, bobbin form, and wave package amplitude modulation earthquakes. The extended coda is the group with more earthquakes and present durations of 50 seconds. Using the moving particle technique, we read the P and S wave arrival times and estimate azimuth arrivals. A P-wave velocity of 3.0 km/s was used to locate the earthquakes, most of the hypocenters are below the volcanic edifice within a circular perimeter of 5 km of radius and its depths are calculated relative to the CEBN elevation as follows. The impulsive arrivals earthquakes present hypocenters between 0 and 1 km while the other groups between 0 and 4 km. Results suggest fluid activity inside the volcanic building that could be related to fumes on the volcano. We conclude that the Ceboruco volcano is active. Therefore, it should be continuously monitored due to the

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Aerial monitoring in active mud volcano by UAV technique

    NASA Astrophysics Data System (ADS)

    Pisciotta, Antonino; Capasso, Giorgio; Madonia, Paolo

    2016-04-01

    UAV photogrammetry opens various new applications in the close range domain, combining aerial and terrestrial photogrammetry, but also introduces low-cost alternatives to the classical manned aerial photogrammetry. Between 2014 and 2015 tree aerial surveys have been carried out. Using a quadrotor drone, equipped with a compact camera, it was possible to generate high resolution elevation models and orthoimages of The "Salinelle", an active mud volcanoes area, located in territory of Paternò (South Italy). The main risks are related to the damages produced by paroxysmal events. Mud volcanoes show different cyclic phases of activity, including catastrophic events and periods of relative quiescence characterized by moderate activity. Ejected materials often are a mud slurry of fine solids suspended in liquids which may include water and hydrocarbon fluids, the bulk of released gases are carbon dioxide, with some methane and nitrogen, usually pond-shaped of variable dimension (from centimeters to meters in diameter). The scope of the presented work is the performance evaluation of a UAV system that was built to rapidly and autonomously acquire mobile three-dimensional (3D) mapping data in a volcanic monitoring scenario.

  6. Using the Landsat Thematic Mapper to detect and monitor active volcanoes - An example from Lascar volcano, northern Chile

    NASA Technical Reports Server (NTRS)

    Francis, P. W.; Rothery, D. A.

    1987-01-01

    The Landsat Thematic Mapper (TM) offers a means of detecting and monitoring thermal features of active volcanoes. Using the TM, a prominent thermal anomaly has been discovered on Lascar volcano, northern Chile. Data from two short-wavelength infrared channels of the TM show that material within a 300-m-diameter pit crater was at a temperature of at least 380 C on two dates in 1985. The thermal anomaly closely resembles in size and radiant temperature the anomaly over the active lava lake at Erta'ale in Ethiopia. An eruption took place at Lascar on Sept. 16, 1986. TM data acquired on Oct. 27, 1986, revealed significant changes within the crater area. Lascar is in a much more active state than any other volcano in the central Andes, and for this reason it merits further careful monitoring. Studies show that the TM is capable of confidently identifying thermal anomalies less than 100 m in size, at temperatures of above 150 C, and thus it offers a valuable means of monitoring the conditions of active or potentially active volcanoes, particularly those in remote regions.

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

    NASA Astrophysics Data System (ADS)

    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

  8. In search of ancestral Kilauea volcano

    USGS Publications Warehouse

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

    2000-01-01

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

  9. International Global Atmospheric Chemistry Programme global emissions inventory activity: Sulfur emissions from volcanoes, current status

    SciTech Connect

    Benkovitz, C.M.

    1995-07-01

    Sulfur emissions from volcanoes are located in areas of volcanic activity, are extremely variable in time, and can be released anywhere from ground level to the stratosphere. Previous estimates of global sulfur emissions from all sources by various authors have included estimates for emissions from volcanic activity. In general, these global estimates of sulfur emissions from volcanoes are given as global totals for an ``average`` year. A project has been initiated at Brookhaven National Laboratory to compile inventories of sulfur emissions from volcanoes. In order to complement the GEIA inventories of anthropogenic sulfur emissions, which represent conditions circa specific years, sulfur emissions from volcanoes are being estimated for the years 1985 and 1990.

  10. Quantitative measurements of active Ionian volcanoes in Galileo NIMS data

    NASA Astrophysics Data System (ADS)

    Saballett, Sebastian; Rathbun, Julie A.; Lopes, Rosaly M. C.; Spencer, John R.

    2016-10-01

    Io is the most volcanically active body in our solar system. The spatial distribution of volcanoes a planetary body's surface gives clues into its basic inner workings (i.e., plate tectonics on earth). Tidal heating is the major contributor to active surface geology in the outer solar system, and yet its mechanism is not completely understood. Io's volcanoes are the clearest signature of tidal heating and measurements of the total heat output and how it varies in space and time are useful constraints on tidal heating. Hamilton et al. (2013) showed through a nearest neighbor analysis that Io's hotspots are globally random, but regionally uniform near the equator. Lopes-Gautier et al. (1999) compared the locations of hotspots detected by NIMS to the spatial variation of heat flow predicted by two end-member tidal heating models. They found that the distribution of hotspots is more consistent with tidal heating occurring in asthenosphere rather than the mantle. Hamilton et al. (2013) demonstrate that clustering of hotspots also supports a dominant role for asthenosphere heating. These studies were unable to account for the relative brightness of the hotspots. Furthermore, studies of the temporal variability of Ionian volcanoes have yielded substantial insight into their nature. The Galileo Near Infrared Mapping Spectrometer (NIMS) gave us a large dataset from which to observe active volcanic activity. NIMS made well over 100 observations of Io over an approximately 10-year time frame. With wavelengths spanning from 0.7 to 5.2 microns, it is ideally suited to measure blackbody radiation from surfaces with temperatures over 300 K. Here, we report on our effort to determine the activity level of each hotspot observed in the NIMS data. We decide to use 3.5 micron brightness as a proxy for activity level because it will be easy to compare to, and incorporate, ground-based observations. We fit a 1-temperature blackbody to spectra in each grating position and averaged the

  11. Catalogue of satellite photography of the active volcanoes of the world

    NASA Technical Reports Server (NTRS)

    Heiken, G.

    1976-01-01

    A catalogue is presented of active volcanoes as viewed from Earth-orbiting satellites. The listing was prepared of photographs, which have been screened for quality, selected from the earth resources technology satellite (ERTS) and Skylab, Apollo and Gemini spacecraft. There is photography of nearly every active volcano in the world; the photographs are particularly useful for regional studies of volcanic fields.

  12. Vertical Motions of Oceanic Volcanoes

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    USGS Publications Warehouse

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

    1996-01-01

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

  14. Coastal submarine hydrothermal activity of Northern Baja California 2. Evolutionary history and isotope geochemistry

    SciTech Connect

    Vidal, V.M.V.; Vidal, F.V.; Isaacs, J.D.

    1981-10-10

    A geochemical model of the Punta Banda submarine hydrothermal system (PBSHS) and Ensenada quadrangle subaerial hot springs is developed using /sup 18/O//sup 16/O, D/H, /sup 34/S//sup 32/S, /sup 3/H, water and gas chemistry. The PBSHS water is a primary high temperature, acid, reducing fluid of old seawater origin which has been titrated by cold, alkaline groundwater of meteoric origin. The final exiting solutions represent a 1:1 mixture of the two primary mixing components. In contrast, the subaerial hot spring waters are of unmixed meteoric origin. The subaerial hot spring gas is predominantly atmospheric N/sub 2/, while the PBSHS contains large amounts of CH/sub 4/ and N/sub 2/ derived from trapped marine sediments of Cretaceous age, deltaS/sup 34/ values of sampled hydrothermal waters are similar to Cretaceous marine sulfate values and suggest that the waters contacted Cretaceous marine sedimentary strata. The presence of the Alisitos and Rosario marine sedimentary formations of Cretaceous age within the Ensenada-Punta Banda quadrangel renders support to the above hypothesis. The data also demonstrate the pyrite mineralization and deposition in submarine hydrothermal environments result from the complexing of ferrous iron with elemental sulfur and sulfide and that submarine hydrothermal activity acts as a major source of silica, Ca/sup 2 +/, and trace metals and as a major sink for seawater Mg/sup 2 +/ and SO/sub 4//sup 2 -/.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Ground-based observations of time variability in multiple active volcanoes on Io

    NASA Astrophysics Data System (ADS)

    Rathbun, Julie A.; Spencer, John R.

    2010-10-01

    Since before the beginning of the Galileo spacecraft's Jupiter orbital tour, we have observed Io from the ground using NASA's Infrared Telescope Facility (IRTF). We obtained images of Io in reflected sunlight and in-eclipse at 2.3, 3.5, and 4.8 μm. In addition, we have measured the 3.5 μm brightness of an eclipsed Io as it is occulted by Jupiter. These lightcurves enable us to measure the brightness and one-dimensional location of active volcanoes on the surface. During the Galileo era, two volcanoes were observed to be regularly active: Loki and either Kanehekili and/or Janus. At least 12 other active volcanoes were observed for shorter periods of time, including one distinguishable in images that include reflected sunlight. These data can be used to compare volcano types and test volcano eruption models, such as the lava lake model for Loki.

  17. Shallow S wave attenuation and actively degassing magma beneath Taal Volcano, Philippines

    NASA Astrophysics Data System (ADS)

    Kumagai, Hiroyuki; Lacson, Rudy; Maeda, Yuta; Figueroa, Melquiades S.; Yamashina, Tadashi

    2014-10-01

    Taal Volcano, Philippines, is one of the world's most dangerous volcanoes given its history of explosive eruptions and its close proximity to populated areas. A real-time broadband seismic network was recently deployed and has detected volcano-tectonic events beneath Taal. Our source location analysis of these volcano-tectonic events, using onset arrival times and high-frequency seismic amplitudes, points to the existence of a region of strong attenuation near the ground surface beneath the east flank of Volcano Island in Taal Lake. This region is beneath the active fumarolic area and above sources of pressure contributing inflation and deflation, and it coincides with a region of high electrical conductivity. The high-attenuation region matches that inferred from an active-seismic survey conducted at Taal in 1993. These features strongly suggest that the high-attenuation region represents an actively degassing magma body near the surface that has existed for more than 20 years.

  18. The recent seismo-volcanic activity at Deception Island volcano

    NASA Astrophysics Data System (ADS)

    Ibáñez, Jesús M.; Almendros, Javier; Carmona, Enrique; Martínez-Arévalo, Carmen; Abril, Miguel

    2003-06-01

    This paper reviews the recent seismic studies carried out at Deception Island, South Shetland Islands, Antarctica, which was monitored by the Argentinean and Spanish Antarctic Programs since 1986. Several types of seismic network have been deployed temporarily during each Antarctic summer. These networks have consisted of a variety of instruments, including radio-telemetered stations, autonomous digital seismic stations, broadband seismometers, and seismic arrays. We have identified two main types of seismic signals generated by the volcano, namely pure seismo-volcanic signals, such as volcanic tremor and long-period (LP) events, and volcano-tectonic (VT) earthquakes. Their temporal distributions are far from homogeneous. Volcanic tremors and LP events usually occur in seismic swarms lasting from a few hours to some days. The number of LP events in these swarms is highly variable, from a background level of less than 30/day to a peak activity of about 100 events/h. The occurrence of VT earthquakes is even more irregular. Most VT earthquakes at Deception Island have been recorded during two intense seismic crises, in 1992 and 1999, respectively. Some of these VT earthquakes were large enough to be felt by researchers working on the island. Analyses of both types of seismic events have allowed us to derive source locations, establish seismic source models, analyze seismic attenuation, calculate the energy and stress drop of the seismic sources, and relate the occurrence of seismicity to the volcanic activity. Pure seismo-volcanic signals are modelled as the consequence of hydrothermal interactions between a shallow aquifer and deeper hot materials, resulting in the resonance of fluid-filled fractures. VT earthquakes constitute the brittle response to changes in the distribution of stress in the volcanic edifice. The two VT seismic series are probably related to uplift episodes due to deep injections of magma that did not reach the surface. This evidence, however

  19. Growth and degradation of Hawaiian volcanoes: Chapter 3 in Characteristics of Hawaiian volcanoes

    USGS Publications Warehouse

    Clague, David A.; Sherrod, David R.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Large Hawaiian volcanoes can persist as islands through the rapid subsidence by building upward rapidly enough. But in the long run, subsidence, coupled with surface erosion, erases any volcanic remnant above sea level in about 15 m.y. One consequence of subsidence, in concert with eustatic changes in sea level, is the drowning of coral reefs that drape the submarine flanks of the actively subsiding volcanoes. At least six reefs northwest of the Island of Hawai‘i form a stairstep configuration, the oldest being deepest.

  20. Evolution of Deformation Studies on Active Hawaiian Volcanoes

    USGS Publications Warehouse

    Decker, Robert; Okamura, Arnold; Miklius, Asta; Poland, Michael

    2008-01-01

    Everything responds to pressure, even rocks. Deformation studies involve measuring and interpreting the changes in elevations and horizontal positions of the land surface or sea floor. These studies are variously referred to as geodetic changes or ground-surface deformations and are sometimes indexed under the general heading of geodesy. Deformation studies have been particularly useful on active volcanoes and in active tectonic areas. A great amount of time and energy has been spent on measuring geodetic changes on Kilauea and Mauna Loa Volcanoes in Hawai`i. These changes include the build-up of the surface by the piling up and ponding of lava flows, the changes in the surface caused by erosion, and the uplift, subsidence, and horizontal displacements of the surface caused by internal processes acting beneath the surface. It is these latter changes that are the principal concern of this review. A complete and objective review of deformation studies on active Hawaiian volcanoes would take many volumes. Instead, we attempt to follow the evolution of the most significant observations and interpretations in a roughly chronological way. It is correct to say that this is a subjective review. We have spent years measuring and recording deformation changes on these great volcanoes and more years trying to understand what makes these changes occur. We attempt to make this a balanced as well as a subjective review; the references are also selective rather than exhaustive. Geodetic changes caused by internal geologic processes vary in magnitude from the nearly infinitesimal - one micron or less, to the very large - hundreds of meters. Their apparent causes also are varied and include changes in material properties and composition, atmospheric pressure, tidal stress, thermal stress, subsurface-fluid pressure (including magma pressure, magma intrusion, or magma removal), gravity, and tectonic stress. Deformation is measured in units of strain or displacement. For example, tilt

  1. Recent Seismic and Geodetic Activity at Multiple Volcanoes in the Ecuadorean Andes

    NASA Astrophysics Data System (ADS)

    Hernandez, S.; Ruiz, M. C.; McCausland, W. A.; Prejean, S. G.; Mothes, P. A.; Bell, A. F.; Hidalgo, S.; Barrington, C.; Yepez, M.; Aguaiza, S.; Plain, M.

    2015-12-01

    The state of volcanic activity often fluctuates between periods of repose and unrest. The transition time between a period of repose and unrest, or vice versa for an open system, can occur within a matter of hours or days. Because of this short time scale, real-time seismic and geodetic (e.g. tiltmeter, GPS) monitoring networks are crucial for characterizing the state of activity of a volcano. In the Ecuadorean Andes, 5 volcanoes demonstrate long-term (Tungurahua, Reventador, and Guagua Pichincha) or recently reactivated (Cotopaxi, Chiles-Cerro Negro) seismic and geodetic activity. The Instituto Geofisico regularly characterizes volcano seismicity into long period, very long period, volcano-tectonic, and tremor events. Significant recent changes at these volcanoes include: rigorous reactivation of glacier-capped Cotopaxi, drumbeat seismicity absent a dome extrusion at Tungurahua, and regularly reoccurring (~7 day recurrence interval), shallow seismic swarms at Guagua Pichincha. These volcanoes locate along both the Western and Eastern Cordillera of the Ecuadorean Andes and, where data are available, manifest important variations in chemical composition, daily gas flux, and surficial deformation. We summarize the long-term geophysical parameters measured at each volcano and place recent changes in each parameter in a larger magmatic and hydrothermal context. All of the studied volcanoes present significant societal hazards to local and regional communities.

  2. Sangay volcano, Ecuador: structural development, present activity and petrology

    NASA Astrophysics Data System (ADS)

    Monzier, Michel; Robin, Claude; Samaniego, Pablo; Hall, Minard L.; Cotten, Jo; Mothes, Patricia; Arnaud, Nicolas

    1999-05-01

    Sangay (5230 m), the southernmost active volcano of the Andean Northern Volcanic Zone (NVZ), sits ˜130 km above a >32-Ma-old slab, close to a major tear that separates two distinct subducting oceanic crusts. Southwards, Quaternary volcanism is absent along a 1600-km-long segment of the Andes. Three successive edifices of decreasing volume have formed the Sangay volcanic complex during the last 500 ka. Two former cones (Sangay I and II) have been largely destroyed by sector collapses that resulted in large debris avalanches that flowed out upon the Amazon plain. Sangay III, being constructed within the last avalanche amphitheater, has been active at least since 14 ka BP. Only the largest eruptions with unusually high Plinian columns are likely to represent a major hazard for the inhabited areas located 30 to 100 km west of the volcano. However, given the volcano's relief and unbuttressed eastern side, a future collapse must be considered, that would seriously affect an area of present-day colonization in the Amazon plain, ˜30 km east of the summit. Andesites greatly predominate at Sangay, there being few dacites and basalts. In order to explain the unusual characteristics of the Sangay suite—highest content of incompatible elements (except Y and HREE) of any NVZ suite, low Y and HREE values in the andesites and dacites, and high Nb/La of the only basalt found—a preliminary five-step model is proposed: (1) an enriched mantle (in comparison with an MORB source), or maybe a variably enriched mantle, at the site of the Sangay, prior to Quaternary volcanism; (2) metasomatism of this mantle by important volumes of slab-derived fluids enriched in soluble incompatible elements, due to the subduction of major oceanic fracture zones; (3) partial melting of this metasomatized mantle and generation of primitive basaltic melts with Nb/La values typical of the NVZ, which are parental to the entire Sangay suite but apparently never reach the surface and subordinate

  3. Abundances of platinum group elements in native sulfur condensates from the Niuatahi-Motutahi submarine volcano, Tonga rear arc: Implications for PGE mineralization in porphyry deposits

    NASA Astrophysics Data System (ADS)

    Park, Jung-Woo; Campbell, Ian H.; Kim, Jonguk

    2016-02-01

    Some porphyry Cu-Au deposits, which are enriched in Pd, are potentially an economic source of Pd. Magmatic volatile phases are thought to transport the platinum group elements (PGEs) from the porphyry source magma to the point of deposition. However, the compatibilities of the PGEs in magmatic volatile phases are poorly constrained. We report PGE and Re contents in native sulfur condensates and associated altered dacites from the Niuatahi-Motutahi submarine volcano, Tonga rear arc, in order to determine the compatibility of PGEs and Re in magmatic volatile phases, and their mobility during secondary hydrothermal alteration. The native sulfur we analyzed is the condensate of a magmatic volatile phase exsolved from the Niuatahi-Motutahi magma. The PGEs are moderately enriched in the sulfur condensates in comparison to the associated fresh dacite, with enrichment factors of 11-285, whereas Au, Cu and Re are strongly enriched with enrichment factors of ∼20,000, ∼5000 and ∼800 respectively. Although the PGEs are moderately compatible into magmatic volatile phases, their compatibility is significantly lower than that of Au, Cu and Re. Furthermore, the compatibility of PGEs decrease in the order: Ru > Pt > Ir > Pd. This trend is also observed in condensates and sublimates from other localities. PGE mineralization in porphyry Cu-Au deposits is characterized by substantially higher Pd/Pt (∼7-60) and Pd/Ir (∼100-10,500) than typical orthomagmatic sulfide deposits (e.g. Pd/Pt ∼0.6 and Pd/Ir ∼20 for the Bushveld). It has previously been suggested that the high mobility of Pd, relative to the other PGEs, may account for the preferential enrichment of Pd in porphyry Cu-Au deposits. However, the low compatibility of Pd in the volatile phase relative to the other PGEs, shown in this study, invalidates this explanation. We suggest that the PGE geochemistry of Pd-rich Cu-Au deposits is principally derived from the PGE characteristics of the magma from which the ore

  4. 2013 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2015-08-14

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

  5. A Fluorescein Tracer Release Experiment in the Hydrothermally Active Crater of Vailulu'u Volcano, Samoa

    NASA Astrophysics Data System (ADS)

    Hart, S. R.; Staudigel, H.; Workman, R.; Koppers, A.; Girard, A.

    2001-12-01

    the layer thickness at 61 percent of the peak concentration. Our data constrain K to be in the range 200-400 cm2/sec. This may be compared with a value of 0.3 cm2/sec measured at 300m in the open ocean and a value of 5-10 cm2/sec measured in the abyssal ocean near rough topography (Ledwell et al. 1998; 2000). Clearly the water in Vailulu'u crater is in active circulation, undoubtedly driven by hydrothermal inputs. Other physical characteristics attest to this as well - gradients in potential density are small below 850 m depth in the crater, with changes ranging from 0-80 parts per billion per meter; commonly the changes in density occur in staircase fashion, and occasionally the gradients are negative. The approximate thermal output of the crater can be estimated as follows. From analysis of water samples, the total Mn budget below 800 meters is 810 kg. With an eddy diffusivity of 300 cm2/sec, the crater will lose about 66 kg of Mn per day. The typical Mn output of a 5 megawatt hot smoker on a ridge is 28 kg/day. Thus it would take several hot smokers, or a thermal output of 10 megawatts, to maintain the observed Mn budget in the crater. We believe this would make John Edmond smile: the serendipitous exploration of an active submarine volcano, in tropical waters, using an icebreaker as a ship-of-opportunity, followed by post-cruise decompression in Tisa's Bare Foot bar, Pago Pago.

  6. Identifying hazard parameter to develop quantitative and dynamic hazard map of an active volcano in Indonesia

    NASA Astrophysics Data System (ADS)

    Suminar, Wulan; Saepuloh, Asep; Meilano, Irwan

    2016-05-01

    Analysis of hazard assessment to active volcanoes is crucial for risk management. The hazard map of volcano provides information to decision makers and communities before, during, and after volcanic crisis. The rapid and accurate hazard assessment, especially to an active volcano is necessary to be developed for better mitigation on the time of volcanic crises in Indonesia. In this paper, we identified the hazard parameters to develop quantitative and dynamic hazard map of an active volcano. The Guntur volcano in Garut Region, West Java, Indonesia was selected as study area due population are resided adjacent to active volcanoes. The development of infrastructures, especially related to tourism at the eastern flank from the Summit, are growing rapidly. The remote sensing and field investigation approaches were used to obtain hazard parameters spatially. We developed a quantitative and dynamic algorithm to map spatially hazard potential of volcano based on index overlay technique. There were identified five volcano hazard parameters based on Landsat 8 and ASTER imageries: volcanic products including pyroclastic fallout, pyroclastic flows, lava and lahar, slope topography, surface brightness temperature, and vegetation density. Following this proposed technique, the hazard parameters were extracted, indexed, and calculated to produce spatial hazard values at and around Guntur Volcano. Based on this method, the hazard potential of low vegetation density is higher than high vegetation density. Furthermore, the slope topography, surface brightness temperature, and fragmental volcanic product such as pyroclastics influenced to the spatial hazard value significantly. Further study to this proposed approach will be aimed for effective and efficient analyses of volcano risk assessment.

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

    PubMed Central

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

    2014-01-01

    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. PMID:24451461

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

    PubMed

    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.

  9. Comparative velocity structure of active Hawaiian volcanoes from 3-D onshore-offshore seismic tomography

    USGS Publications Warehouse

    Park, J.; Morgan, J.K.; Zelt, C.A.; Okubo, P.G.; Peters, L.; Benesh, N.

    2007-01-01

    We present a 3-D P-wave velocity model of the combined subaerial and submarine portions of the southeastern part of the Island of Hawaii, based on first-arrival seismic tomography of marine airgun shots recorded by the onland seismic network. Our model shows that high-velocity materials (6.5-7.0??km/s) lie beneath Kilauea's summit, Koae fault zone, and the upper Southwest Rift Zone (SWRZ) and upper and middle East Rift Zone (ERZ), indicative of magma cumulates within the volcanic edifice. A separate high-velocity body of 6.5-6.9??km/s within Kilauea's lower ERZ and upper Puna Ridge suggests a distinct body of magma cumulates, possibly connected to the summit magma cumulates at depth. The two cumulate bodies within Kilauea's ERZ may have undergone separate ductile flow seaward, influencing the submarine morphology of Kilauea's south flank. Low velocities (5.0-6.3??km/s) seaward of Kilauea's Hilina fault zone, and along Mauna Loa's seaward facing Kao'iki fault zone, are attributed to thick piles of volcaniclastic sediments deposited on the submarine flanks. Loihi seamount shows high-velocity anomalies beneath the summit and along the rift zones, similar to the interpreted magma cumulates below Mauna Loa and Kilauea volcanoes, and a low-velocity anomaly beneath the oceanic crust, probably indicative of melt within the upper mantle. Around Kilauea's submarine flank, a high-velocity anomaly beneath the outer bench suggests the presence of an ancient seamount that may obstruct outward spreading of the flank. Mauna Loa's southeast flank is also marked by a large, anomalously high-velocity feature (7.0-7.4??km/s), interpreted to define an inactive, buried volcanic rift zone, which might provide a new explanation for the westward migration of Mauna Loa's current SWRZ and the growth of Kilauea's SWRZ. ?? 2007 Elsevier B.V. All rights reserved.

  10. Risk-Free Volcano Observations Using an Unmanned Autonomous Helicopter: seismic observations near the active vent of Sakurajima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Ohminato, T.; Kaneko, T.; Koyama, T.; Yasuda, A.; Watanabe, A.; Takeo, M.; Honda, Y.; Kajiwara, K.; Kanda, W.; Iguchi, M.; Yanagisawa, T.

    2010-12-01

    Observations in the vicinity of summit area of active volcanoes are important not only for understanding physical processes in the volcanic conduit but also for eruption prediction and volcanic hazards mitigation. It is, however, challenging to install observation sensors near active vents because of the danger of sudden eruptions. We need safe and efficient ways of installing sensors near the summit of active volcanoes. We have been developing an volcano observation system based on an unmanned autonomous vehicle (UAV) for risk-free volcano observations. Our UAV is an unmanned autonomous helicopter manufactured by Yamaha-Motor Co., Ltd. The UAV is 3.6m long and weighs 84kg with maximum payload of 10kg. The UAV can aviate autonomously along a previously programmed path within a meter accuracy using real-time kinematics differential GPS equipment. The maximum flight time and distance from the operator are 90 minutes and 5km, respectively. We have developed various types of volcano observation techniques adequate for the UAV, such as aeromagnetic survey, taking infrared and visible images from onboard high-resolution cameras, volcanic ash sampling in the vicinity of active vents. Recently, we have developed an earthquake observation module (EOM), which is exclusively designed for the UAV installation in the vicinity of active volcanic vent. In order to meet the various requirements for UAV installation, the EOM is very compact, light-weight (5-6kg), and is solar-powered. It is equipped with GPS for timing, a communication device using cellular-phone network, and triaxial accelerometers. Our first application of the EOM installation using the UAV is one of the most active volcanoes in Japan, Sakurajima volcano. Since 2006, explosive eruptions have been continuing at the reopened Showa crater at the eastern flank near the summit of Sakurajima. Entering the area within 2 km from the active craters is prohibited, and thus there were no observation station in the vicinity

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

    NASA Astrophysics Data System (ADS)

    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

  12. Late-stage summit activity of Martian shield volcanoes

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, P. J.

    1982-01-01

    The preservation of morphologically fresh lava flows which pre-date the most recent episodes of caldera collapse at the summits of Ascraeus, Arsia and Olympus Montes indicates that explosive eruptions were not associated with this stage of Tharsis shield volcanism. The existence of resurfaced floor segments, complex wrinkle ridges, and lava terraces within the summit craters suggests that lava lakes comprised the dominant form of the intra-caldera activity. Multiple collapse episodes on Ascraeus and Olympus Montes are indicated by the nested summit craters. The most plausible cause of caldera collapse appears to be large-scale sub-terminal effusive activity, which is corroborated by the previously recognized existence of large lava flows on the flanks of these volcanoes. Due to the implied sequence of large-scale explosive (silicic) volcanism followed by effusive (basaltic) activity, it appears highly unlikely that ignimbrites or other forms of pyroclastic flows (previously proposed as possible deposits within the Olympus Mons aureole material) were ever erupted from the Tharsis Montes.

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

    NASA Astrophysics Data System (ADS)

    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

  14. Virtual Investigations of an Active Deep Sea Volcano

    NASA Astrophysics Data System (ADS)

    Sautter, L.; Taylor, M. M.; Fundis, A.; Kelley, D. S.; Elend, M.

    2013-12-01

    Axial Seamount, located on the Juan de Fuca spreading ridge 300 miles off the Oregon coast, is an active volcano whose summit caldera lies 1500 m beneath the sea surface. Ongoing construction of the Regional Scale Nodes (RSN) cabled observatory by the University of Washington (funded by the NSF Ocean Observatories Initiative) has allowed for exploration of recent lava flows and active hydrothermal vents using HD video mounted on the ROVs, ROPOS and JASON II. College level oceanography/marine geology online laboratory exercises referred to as Online Concept Modules (OCMs) have been created using video and video frame-captured mosaics to promote skill development for characterizing and quantifying deep sea environments. Students proceed at their own pace through a sequence of short movies with which they (a) gain background knowledge, (b) learn skills to identify and classify features or biota within a targeted environment, (c) practice these skills, and (d) use their knowledge and skills to make interpretations regarding the environment. Part (d) serves as the necessary assessment component of the laboratory exercise. Two Axial Seamount-focused OCMs will be presented: 1) Lava Flow Characterization: Identifying a Suitable Cable Route, and 2) Assessing Hydrothermal Vent Communities: Comparisons Among Multiple Sulfide Chimneys.

  15. Submarine landslides in Society and Austral Islands, French Polynesia: Evolution with the age of the edifices

    NASA Astrophysics Data System (ADS)

    Clouard, V.; Bonneville, A.

    2003-04-01

    This paper presents descriptions of numerous submarine landslides in French Polynesia. This inventory shows an evolution of the landslide type with the age of oceanic islands. Submarine active volcanoes are subject to superficial landslides of fragmental material whereas young islands exhibit marks of mass wasting corresponding to giant lateral collapses due to debris avalanche that occurred during the period of volcanic activity. Later, erosional processes generate sand-rubble flows and lead the islands to the stellate morphology known on atolls and guyots. In addition, Tupai atoll and Rurutu Island have been subject to giant slump that deeply modify their shape.

  16. Shallow outgassing changes disrupt steady lava lake activity, Kilauea Volcano

    NASA Astrophysics Data System (ADS)

    Patrick, M. R.; Orr, T. R.; Swanson, D. A.; Lev, E.

    2015-12-01

    Persistent lava lakes are a testament to sustained magma supply and outgassing in basaltic systems, and the surface activity of lava lakes has been used to infer processes in the underlying magmatic system. At Kilauea Volcano, Hawai`i, the lava lake in Halema`uma`u Crater has been closely studied for several years with webcam imagery, geophysical, petrological and gas emission techniques. The lava lake in Halema`uma`u is now the second largest on Earth, and provides an unprecedented opportunity for detailed observations of lava lake outgassing processes. We observe that steady activity is characterized by continuous southward motion of the lake's surface and slow changes in lava level, seismic tremor and gas emissions. This normal, steady activity can be abruptly interrupted by the appearance of spattering - sometimes triggered by rockfalls - on the lake surface, which abruptly shifts the lake surface motion, lava level and gas emissions to a more variable, unstable regime. The lake commonly alternates between this a) normal, steady activity and b) unstable behavior several times per day. The spattering represents outgassing of shallowly accumulated gas in the lake. Therefore, although steady lava lake behavior at Halema`uma`u may be deeply driven by upwelling of magma, we argue that the sporadic interruptions to this behavior are the result of shallow processes occurring near the lake surface. These observations provide a cautionary note that some lava lake behavior is not representative of deep-seated processes. This behavior also highlights the complex and dynamic nature of lava lake activity.

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

    NASA Astrophysics Data System (ADS)

    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

  18. Active control of sound radiated by a submarine in bending vibration

    NASA Astrophysics Data System (ADS)

    Caresta, Mauro

    2011-02-01

    This paper theoretically investigates the use of inertial actuators to reduce the sound radiated by a submarine hull in bending vibration under harmonic excitation from the propeller. The radial forces from the propeller are tonal at the blade passing frequency and are transmitted to the hull through the stern end cone. The hull is modelled as a fluid loaded cylindrical shell with ring stiffeners and two equally spaced bulkheads. The cylinder is closed by end-plates and conical end caps. The actuators are arranged in circumferential arrays and attached to the prow end cone. Both Active Vibration Control and Active Structural Acoustic Control are analysed. The inertial actuators can provide control forces with a magnitude large enough to reduce the sound radiated by the vibrations of the hull in some frequency ranges.

  19. Reawakening of a volcano: Activity beneath Eyjafjallajökull volcano from 1991 to 2009

    NASA Astrophysics Data System (ADS)

    Hjaltadóttir, Sigurlaug; Vogfjörd, Kristín S.; Hreinsdóttir, Sigrún; Slunga, Ragnar

    2015-10-01

    The ice-capped Eyjafjallajökull volcano, south Iceland, had been dormant for 170 years when the first signs of reawakening of the volcano were captured by seismic and geodetic measurements in 1994. These were the first clear observed signs of unrest followed by 16 years of intermittent magmatic unrest culminating in 2010 when two eruptions broke out on the flank and at the summit. We analyze seismic data from 1991 through 2008 and GPS data from 1992 to May 2009 to infer magma movements beneath the volcano. The relocated earthquakes reveal an overall pipe-like pattern northeast of the summit crater, sporadically mapping the pathway of magma from the base of the crust towards an intrusion in the upper crust. During the study period, three major seismic swarms were recorded. Two of them, in 1994 and 1999-2000, occurred in the upper and intermediate crust and accompanied crustal deformation centered at the southeastern flank. No uplift was detected during the 19- to 25-km-deep 1996 swarm, near the crust-mantle boundary, but the horizontal, ~ E-W oriented T-axes indicate a period of tension/opening, suggesting magma intruding up into the base of the crust. The GPS measured deformation during 1999-2000 can be modeled as intrusion of a horizontal, circular sill with volume of 0.030 ± 0.007 km3 at 5.0 ± 1.3 km depth. The less constrained 4.5- to 5-km-deep sill model for the 1994 episode indicates a three times smaller intruded volume (0.011 km3) than during 1999-2000. In the years between/following the intrusions, contraction was observed at the southeastern flank. The contraction from 2000.5 to 2009.3 can be fitted by a circular sill model with a volume contraction of - 0.0015 ± 0.0003 km3/year at 5.5 ± 2.0 km depth. The less well constrained model for 1994.7 to 1998.6 gives a volume contraction of -(0.0009-0.0010) km3 at a fixed depth of 5 km. The accumulated volume changes (~- 0.013 km3 for the second period, ~ 0.0037 km3 for the first period) are much larger than

  20. Reventador Volcano 2005: Eruptive activity inferred from seismo-acoustic observation

    NASA Astrophysics Data System (ADS)

    Lees, Jonathan M.; Johnson, Jeffrey B.; Ruiz, Mario; Troncoso, Liliana; Welsh, Matt

    2008-09-01

    Reventador Volcano entered an eruptive phase in 2005 which included a wide variety of seismic and infrasonic activity. These are described and illustrated: volcano-tectonic, harmonic tremor, drumbeats, chugging and spasmodic tremor, long period and very long period events. The recording of this simultaneous activity on an array of three broadband, seismo-acoustic instruments provides detailed information of the state of the conduit and vent during this phase of volcanic eruption. Quasi-periodic tremor at Reventador is similar to that observed at other volcanoes and may be used as an indicator of vent aperture. Variations in the vibration modes of the volcano, frequency fluctuations and rapid temporal fluctuations suggest the influx of new material, choking of the vent and possible modification of the conduit geometry during explosions and effusion over a period of six weeks.

  1. Volcanoes. A planetary perspective.

    NASA Astrophysics Data System (ADS)

    Francis, P.

    In this book, the author gives an account of the familiar violent aspects of volcanoes and the various forms that eruptions can take. He explores why volcanoes exist at all, why volcanoes occur where they do, and how examples of major historical eruptions can be interpreted in terms of physical processes. Throughout he attempts to place volcanism in a planetary perspective, exploring the pre-eminent role of submarine volcanism on Earth and the stunning range of volcanic phenomena revealed by spacecraft exploration of the solar system.

  2. Submarine landslides

    USGS Publications Warehouse

    Hampton, M.A.; Lee, H.J.; Locat, J.

    1996-01-01

    Landslides are common on inclined areas of the seafloor, particularly in environments where weak geologic materials such as rapidly deposited, finegrained sediment or fractured rock are subjected to strong environmental stresses such as earthquakes, large storm waves, and high internal pore pressures. Submarine landslides can involve huge amounts of material and can move great distances: slide volumes as large as 20,000 km3 and runout distances in excess of 140 km have been reported. They occur at locations where the downslope component of stress exceeds the resisting stress, causing movement along one or several concave to planar rupture surfaces. Some recent slides that originated nearshore and retrogressed back across the shoreline were conspicuous by their direct impact on human life and activities. Most known slides, however, occurred far from land in prehistoric time and were discovered by noting distinct to subtle characteristics, such as headwall scarps and displaced sediment or rock masses, on acoustic-reflection profiles and side-scan sonar images. Submarine landslides can be analyzed using the same mechanics principles as are used for occurrences on land. However, some loading mechanisms are unique, for example, storm waves, and some, such as earthquakes, can have greater impact. The potential for limited-deformation landslides to transform into sediment flows that can travel exceedingly long distances is related to the density of the slope-forming material and the amount of shear strength that is lost when the slope fails.

  3. Analysis of Active Lava Flows on Kilauea Volcano, Hawaii, Using SIR-C Radar Correlation Measurements

    NASA Technical Reports Server (NTRS)

    Zebker, H. A.; Rosen, P.; Hensley, S.; Mouginis-Mark, P. J.

    1995-01-01

    Precise eruption rates of active pahoehoe lava flows on Kilauea volcano, Hawaii, have been determined using spaceborne radar data acquired by the Space Shuttle Imaging Radar-C (SIR-C). Measurement of the rate of lava flow advance, and the determination of the volume of new material erupted in a given period of time, are among the most important observations that can be made when studying a volcano.

  4. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Neal, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analyzed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analyzed using data from the European Remote Sensing Satellites (ERS), Japanese Earth Resources Satellite (JERS) and the U. S. Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  5. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Near, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of the Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analysed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analysed using data from the European Remote Sensing Satellites (ERS), the Japanese Earth Resources Satellite (JERS) and the US Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  6. Rapid Changes on Sediment Accumulation Rates within Submarine Canyons Caused By Bottom Trawling Activities

    NASA Astrophysics Data System (ADS)

    Puig, P.; Masque, P.; Martin, J.; Paradis, S.; Juan, X.; Toro, M.; Palanques, A.

    2014-12-01

    The physical disturbance of the marine sedimentary environments by commercial bottom trawling is a matter of concern. The direct physical effects of this fishing technique include scraping and ploughing of the seabed and increases of the near-bottom water turbidity by sediment resuspension. However, the quantification of the sediment that has been resuspended by this anthropogenic activity over years and has been ultimately exported across the margin remains largely unaddressed. The analysis of sediment accumulation rates from sediment cores collected along the axes of several submarine canyons in the Catalan margin (northwestern Mediterranean) has allowed to estimate the contribution of this anthropogenic activity to the present-day sediment dynamics. 210Pb chronologies, occasionally supported by 137Cs dating, indicate a rapid increase of sediment accumulation rates since the 1970s, in coincidence with a strong impulse in the industrialization of the trawling fleets of this region. Such increase has been associated to the enhanced delivery of sediment resuspended by trawlers from the shelves and upper slope regions towards the canyon's interior, and to the rapid technical development at that time, in terms of engine power and gear size. This change has been observed in La Fonera (or Palamós) Canyon at depths greater than 1700 m, while in other canyons it is restricted to shallower regions (~1000 m in depth) closer to fishing grounds. Two sampling sites from La Fonera and Foix submarine canyons that exhibited high sediment accumulation rates (0.6-0.7 cm/y) were reoccupied several years after the first chronological analyses. These two new cores reveal a second and more rapid increase of sediment accumulation rates in both canyons occurring circa 2002 and accounting for about 2 cm/y. This second change at the beginning of the XXI century has been attributed to a preferential displacement of the trawling fleet towards slope fishing grounds surrounding submarine

  7. Fifteen years of thermal activity at Vanuatu's volcanoes (2000-2015) revealed by MIROVA

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    The Vanuatu archipelago consists of 80 islands and hosts 5 subaerial volcanoes (Yasur, Lopevi, Ambrym, Aoba and Gaua) that have shown sign of activity during the past decade. In this contribution we provide a 15 years-long datasets (2000-2015) of the thermal activity recorded at these active volcanoes by means of MIROVA (Middle InfraRed Observation of Volcanic Activity) a new volcanic hotspot detection system based on MODIS data. The analyzed volcanoes are characterized by a spectrum of volcanic activities whose thermal signature has been tracked and carefully analyzed. These include strombolian-vulcanian explosions at Yasur, lava flows at Lopevi, lava lakes at Ambrym, surtseyan-type eruptions within the Voui crater lake of Aoba and ash-dominated eruptions with strong degassing at Gaua. The collected data reveal several details of the long term eruptive dynamics at single sites such as a monthly long pulse in thermal emissions at Yasur volcano as well as at the two active craters of Ambrym (Benbow and Marum). Heating cycles within Aoba crater lake and intermittent pressurized eruptions at Lopevi volcano has also been detected and shed light in the eruptive dynamics of the analyzed volcanoes. In addition we were able to track a two years long intensification of thermal output at Benbow crater (Ambrym) that preceded the occurrence of the first intra-caldera eruptions of this volcano since 1989. We emphasize how the data provided by MIROVA represent a new, safe and affordable method for monitoring in near-real time a large spectrum of volcanic activities taking place at Vanuatu and other volcanic areas.

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

    NASA Astrophysics Data System (ADS)

    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

  9. 2010 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2014-01-01

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

  10. Volcanic evolution of the submarine super volcano, Tamu Massif of Shatsky Rise: New insights from Formation MicroScanner logging imagery

    NASA Astrophysics Data System (ADS)

    Tominaga, Masako; Iturrino, Gerardo; Evans, Helen F.

    2015-01-01

    Massif, the southernmost plateau of Shatsky Rise, is recently reported as the largest single volcano known on Earth. This work seeks to understand the type of volcanism necessary to form such an anomalously large single volcano by integrating core and high-resolution wireline logging data. In particular, resistivity imagery obtained by the Formation MicroScanner, in Integrated Ocean Drilling Program Hole U1347A, located on the eastern flank of Tamu Massif, was used to construct a logging-based volcanostratigraphy. This model revealed two different volcanic stages formed Tamu Massif: (i) the core part of the massif's basaltic basement was formed by a "construction phase" of volcanism with cyclic eruption events from a steady state magma supply and (ii) the very topmost basaltic section was formed by a "depositional phase" of volcanism during which long-traveling lava flows were deposited from a distant eruption center.

  11. Volcanoes: Nature's Caldrons Challenge Geochemists.

    ERIC Educational Resources Information Center

    Zurer, Pamela S.

    1984-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  13. 2009 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2014-01-01

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

  14. Prokaryotic diversity of an active mud volcano in the Usu City of Xinjiang, China.

    PubMed

    Yang, Hong-Mei; Lou, Kai; Sun, Jian; Zhang, Tao; Ma, Xiao-Long

    2012-02-01

    The Usu mud volcanoes are the largest group of terrestrial mud volcanoes in China. The volcanoes are located in a typical arid and semi-arid region, and the group consists of 36 erupting active mud volcanoes. In this study, the prokaryotic diversity and community structure in the sediment of an active mud volcano were investigated by constructing bacterial and archaeal clone libraries of the 16S rRNA gene. A total of 100 bacterial and 100 archaeal clones were analysed and found to comprise 11 and 7 distinct phylotypes, respectively. The bacterial phylotypes were classified into three phyla (Proteobacteria, Actinobacteria, and Fusobacteria). Of these, Proteobacteria were the most abundant bacterial group, with Deltaproteobacteria dominating the sediment community, and these were affiliated with the order Desulfuromonadales. The archaeal phylotypes were all closely related to uncultivated species, and the majority of the members were related to the orders Methanosarcinales and Halobacteriales of the Euryarchaeota originating from methane hydrate bearing or alkaline sediments. The rest of the archaeal phylotypes belonged to the phylum Crenarchaeota, with representatives from similar habitats. These results suggested that a large number of novel microbial groups and potential methanogenesis may exist in this unique ecosystem.

  15. Acoustic scattering from mud volcanoes and carbonate mounds.

    PubMed

    Holland, Charles W; Weber, Thomas C; Etiope, Giuseppe

    2006-12-01

    Submarine mud volcanoes occur in many parts of the world's oceans and form an aperture for gas and fluidized mud emission from within the earth's crust. Their characteristics are of considerable interest to the geology, geophysics, geochemistry, and underwater acoustics communities. For the latter, mud volcanoes are of interest in part because they pose a potential source of clutter for active sonar. Close-range (single-interaction) scattering measurements from a mud volcano in the Straits of Sicily show scattering 10-15 dB above the background. Three hypotheses were examined concerning the scattering mechanism: (1) gas entrained in sediment at/near mud volcano, (2) gas bubbles and/or particulates (emitted) in the water column, (3) the carbonate bio-construction covering the mud volcano edifice. The experimental evidence, including visual, acoustic, and nonacoustic sensors, rules out the second hypothesis (at least during the observation time) and suggests that, for this particular mud volcano the dominant mechanism is associated with carbonate chimneys on the mud volcano. In terms of scattering levels, target strengths of 4-14 dB were observed from 800 to 3600 Hz for a monostatic geometry with grazing angles of 3-5 degrees. Similar target strengths were measured for vertically bistatic paths with incident and scattered grazing angles of 3-5 degrees and 33-50 degrees, respectively.

  16. Hydrogen Isotopic Composition of Hornblendes From Active Volcanoes of Mexico

    NASA Astrophysics Data System (ADS)

    Taran, Y.; Kusakabe, M.; Valdez, G.; Mora, J. C.

    2002-12-01

    Horblendes (Hb) crystallize in water-rich magmas in magma chambers or in deeper zones. Isotopic composition of hydrogen in OH-groups of Hb represents the water isotopic composition of magmatic fluid or dissolved magmatic volatiles and therefore, is an isotopic characteristics of magmatic water. At lower vapor pressure in conduits and shallower magma chambers, Hb can decompose and loose water with significant isotopic effects. We measured hydrogen isotopic composition of hornblendes from modern lavas and pyroclastics of El Chichon, Colima and Popocatepetl volcanoes. Hornblendes from the last and previous pyroclastic flows of El Chichon are the more abundant mineral phases (after plagioclase), showing pleochroism from green to brown. They are relatively uniform in composition (close to magnesian hastingsite hornblende), without chemical variations between cores and rims. Using the Johnson and Rutherford (1989) calibration of the Al-in-hornblende geobarometer, the hornblendes show equilibrium with the melt at pressure of 4 kb that correspond to 12 km of depth. These pressure conditions likely represent the location of the magma chamber below El Chichon volcano, however, these pressure estimates need to be confirmed. The water content of all analyzed Hbs is 1.5-1.8 wt%, but may be higher due to a minor amount of impurities of pyroxenes which sometimes are difficult to separate from Hb. Hydrogen isotopic composition in 10 samples of Hb from El Chichon of different age and facies (pumice, lithic fragments in pyroclastics) was in a narrow range -40 to -37 permil V-SMOW. Such isotopic signature corresponds to so-called "andesitic" waters, i.e. waters from subduction-related magmas, The origin of these waters is suggested to be the recycled water from subducted oceanic sediments. The data for El Chichon volcano are in the range of the already known values for subduction-related magmas though the tectonic setting of El Chichon is more complicated. The measured isotopic

  17. Titan Submarines!

    NASA Astrophysics Data System (ADS)

    Oleson, S. R.; Lorenz, R. D.; Paul, M. V.; Hartwig, J. W.; Walsh, J. M.

    2017-02-01

    A NIAC Phase II submarine concept, dubbed 'Titan Turtle' for Saturn's moon Titan's northern sea, Ligea Mare. A design concept including science and operations is described for this -180°C liquid methane sea.

  18. Hydrogochemical tools for monitoring active volcanoes: Applications to El Chichón volcano, México.

    NASA Astrophysics Data System (ADS)

    Armienta, M. A.; de La Cruz-Reyna, S.; Ramos, S.; Morton, O.; Ceniceros, N.; Aguayo, A.; Cruz, O.

    2010-03-01

    In 1982, a series of eruptions resulted in the worst disaster linked with volcanic activity in México. The characteristics of the phenomena together with a lack of prevention measures resulted in approximately 2000 deaths. An important aspect to prevent disasters is a thorough knowledge and monitoring of the potentially destructive natural phenomena. Monitoring the activity of dormant or active volcanoes by various methods is thus a key measure to estimate the hazard and design adequate risk reduction measures. Despite of the 1982 volcanic disaster, until only a few years, hydrogeochemical monitoring was the only regular surveillance of El Chichón post-eruptive activity. The first samples of the crater-lake water were collected by Casadevall et al. in 1983. Since 1985, a systematic sampling and chemical analyses program has been carried out by the Geophysics Institute in collaboration with local authorities from the State of Chiapas. Chemical analyses of main ions and Rare Earth elements (REE) are performed in the Laboratorio de Química Analítica and Laboratorio ICP-MS of the Instituto de Geofísica, UNAM. Results are interpreted considering the physico-chemical changes that may be recognized as precursors of volcanic activity. The problem is difficult because at least two main water reservoirs feed the crater lake; besides, dissolution of acid volcanic gases, water-rock interactions and geochemical processes among dissolved species have resulted in a complex chemical behavior of the lake-water along the years. The calculated degree of neutralization, pH values, and chloride and sulfate concentrations of samples taken at different dates result in a classification of the volcano as active or inactive according to the method developed by Varekamp. A pH of 0.5, very high conductivity and a temperature of about 50°C characterized the first years following the eruptions. An overall decrease on the temperature and ionic concentrations, along with a less acid p

  19. Infrasound Monitoring of the Volcanic Activities of Japanese Volcanoes in Korea

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. Temporal Variations of Magnetic Field Associated with Seismic Activity at Cerro Machin Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Londono, J. M.; Serna, J. P.; Guzman, J.

    2011-12-01

    A study of magnetic variations was carried out at Cerro Machin Volcano, Colombia for the period 2009 -2010, with two permanent magnetometers located at South and North of the central dome, separated about 2.5 km each other. After corrections, we found that there is no clear correlation between volcanic seismicity and temporal changes of magnetic field for each magnetometer station, if they are analyzed individually. On the contrary, when we calculated the residual Magnetic field (RMF), for each magnetometer, and then we made the subtraction between them, and plot it vs time, we found a clear correlation of changes in local magnetic field with the occurrence of volcanic seismicity (ML >1.6). We found a change in the RMF between 1584 nT and 1608 nT, each time that a volcano-tectonic earthquake occurred. The máximum lapse time between the previous change in RMF and the further occurrence of the earthquake is 24 days, with an average of 11 days. This pattern occurred more than 9 times during the studied period. Based on the results, we believed that the simple methodology proposed here, is a good tool for monitoring changes in seismicity associated with activity at Cerro Machín volcano. We suggest that the temporal changes of RMF at Cerro Machín Volcano, are associated with piezo-magnetic effects, due to changes in strain-stress inside the volcano, produced by the interaction between local faulting and magma movement.

  1. Dante's Volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

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

  2. Methods of InSAR atmosphere correction for volcano activity monitoring

    USGS Publications Warehouse

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

    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.

  3. Addressing submarine geohazards through scientific drilling

    NASA Astrophysics Data System (ADS)

    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

  4. Inside active volcanoes; an exhibit on the move!

    USGS Publications Warehouse

    Fiske, R.S.

    1990-01-01

    All of us are aware of the emphasis currently being placed in the United States on science education and public understanding of science. Most of this emphasis is directed toward mass audiences through book publications, school curricula, and television programs; sadly, most of it deals with non-earth science topics. In an effort to take advantage of this awakened consciousness and to highlight the earth sciences, the Smithsonian Institution and the U.S Geological Survey joined forces to prepare a traveling exhibit on volcanoes that is currently touring the country. This note will serve to bring you up to date on the progress of this exhibit as it reaches the mid-point of its tour. 

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  6. VEPP Exercise: Volcanic Activity and Monitoring of Pu`u `O`o, Kilauea Volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Rodriguez, L. A.

    2010-12-01

    A 10-week project will be tested during the Fall semester 2010, for a Volcanic Hazards elective course, for undergraduate Geology students of the University of Puerto Rico at Mayaguez. This exercise was developed during the Volcanoes Exploration Project: Pu`u `O`o (VEPP) Workshop, held on the Big Island of Hawaii in July 2010. For the exercise the students will form groups (of 2-4 students), and each group will be assigned a monitoring technique or method, among the following: seismic (RSAM data), deformation (GPS and tilt data), observations (webcam and lava flow maps), gas and thermal monitoring. The project is designed for Geology undergraduates who have a background in introductory geology, types of volcanoes and eruptions, magmatic processes, characteristics of lava flows, and other related topics. It is divided in seven tasks, starting with an introduction and demonstration of the VEPP website and the VALVE3 software, which is used to access monitoring data from the current eruption of Pu`u `O`o, Kilauea volcano, Hawaii. The students will also familiarize themselves with the history of Kilauea volcano and its current eruption. At least weekly the groups will acquire data (mostly near-real-time) from the different monitoring techniques, in the form of time series, maps, videos, and images, in order to identify trends in the data. The groups will meet biweekly in the computer laboratory to work together in the analysis and interpretation of the data, with the support of the instructor. They will give reports on the progress of the exercise, and will get feedback from the instructor and from the other expert groups. All groups of experts will relate their findings to the recent and current activity of Kilauea volcano, and the importance of their specific type of monitoring. The activity will culminate with a written report and an oral presentation. The last task of the project consists of a wrap-up volcano monitoring exercise, in which the students will

  7. Extensive Submarine Active Fault and the 2011 off the Pacific Coast of Tohoku Earthquake

    NASA Astrophysics Data System (ADS)

    Nakata, T.; Kumamoto, T.; Muroi, S.; Watanabe, M.

    2013-12-01

    Active faults observed on seafloor along Japan Trench are resultants of repeated large earthquakes. We discuss on the relation between large earthquakes and their source faults based on a detailed active fault map along Japan Trench. Judging from location and continuation of active faults in the earthquake source area, we consider that one of the extensive thrust faults which extends from off-Sanriku to off-Ibaraki for about 500km, is directly related to the source fault of the 2011 off the Pacific coast of Tohoku Earthquake. The 2011 off the Pacific Coast of Tohoku Earthquake (Mw9.0) generated large tsunami with massive pulsating pattern of waves (Maeda et al. 2011). A leading hypothesis believed among many seismologists that an earthquake source fault that generated the earthquake, caused the near-surface fault rupture along the axis of Japan Trench, and large displacement ~50m eastward and ~7 to ~10m upward was estimated from comparison of data obtained before and after the earthquake in 2004 and 2011 by multibeam bathymetric surveys across the trench (Fujiwara et al. 2011). Satake et al. (2011) explained the large tsunami height by simultaneous faulting on two different fault planes, one on subducting plate boundary and the other near the trench axis. Since most of the workers hypothesized without any doubt believed that the earthquake was caused by the fault ruptured up to the trench axis, existence of submarine active fault is rather overlooked so far. However, we consider the large displacement is due to landslide and do not find any extensive fault scarp on the trench axis. We simulated pattern of seafloor deformation associated with the earthquake using a simple dislocation model for a single fault plane with uniform slip that dips 14 degree in depth and 33.6 degree beneath the tectonic bulge related to the extensive active fault. A result shows that an area of large uplift agrees more or less with the location of tectonic bulge with width of about 20km

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

    PubMed

    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.

  9. Volcano Infrasound

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Fee, D.; Matoza, R. S.

    2013-12-01

    Open-vent volcanoes generate prodigious low frequency sound waves that tend to peak in the infrasound (<20 Hz) band. These long wavelength (> ~20 m) atmospheric pressure waves often propagate long distances with low intrinsic attenuation and can be well recorded with a variety of low frequency sensitive microphones. Infrasound records may be used to remotely monitor eruptions, identify active vents or track gravity-driven flows, and/or characterize source processes. Such studies provide information vital for both scientific study and volcano monitoring efforts. This presentation proposes to summarize and standardize some of the terminology used in the still young, yet rapidly growing field of volcano infrasound. Herein we suggest classification of typical infrasound waveform types, which include bimodal pulses, blast (or N-) waves, and a variety of infrasonic tremors (including broadband, harmonic, and monotonic signals). We summarize various metrics, including reduced pressure, intensity, power, and energy, in which infrasound excess pressures are often quantified. We also describe the spectrum of source types and radiation patterns, which are typically responsible for recorded infrasound. Finally we summarize the variety of propagation paths that are common for volcano infrasound radiating to local (<10 km), regional (out to several hundred kilometers), and global distances. The effort to establish common terminology requires community feedback, but is now timely as volcano infrasound studies proliferate and infrasound becomes a standard component of volcano monitoring.

  10. Ultra-high Resolution Mapping of the Inner Crater of the Active Kick'em Jenny Volcano

    NASA Astrophysics Data System (ADS)

    Hart, L.; Scott, C.; Tominaga, M.; Smart, C.; Vaughn, I.; Roman, C.; Carey, S.; German, C. R.; Participants, T.

    2015-12-01

    We conducted high-resolution geological characterization of a 0.015km^2 region of the inner crater of the most active submarine volcano in the Caribbean, Kick'em Jenny, located 8 km off Grenada in the Lesser Antilles Island Arc. We obtained digital still images and microbathymetery at an altitude of 3 m from the seafloor by using stereo cameras and a BlueView system mounted on Remotely Operated Vehicle (ROV) Hercules during the NA054 cruise on E/V Nautilus (Sept. - Oct. 2014). The seafloor images were processed to construct 2-D photo mosaics of the survey area using Standard Hercules Imaging Suite. We systematically classified the photographed seafloor geology based on the distribution of seafloor morphology and the observable rock fragment and outcrop sizes. The center of the crater floor shows a smooth, coherent texture with little variation in sea floor morphology. From immediately outside this area toward the crater rim, we observe an extensive area covered with outcrops, small rocks, and sediment: and within this area, (1) the north section is partially covered by uneven outcrops with elongated lineaments and a course, rugged seafloor with individual rock fragments observable; (2) the middle section contains high variability and heterogeneity in seafloor morphology in a non-systematic manner; and (3) overall, the southern most section displays subdued seafloor features both in space and variability compared to the other areas. The distributions of rock fragments were classified into four distinct sizes. We observe: (i) little variation in size distribution near the center of the crater floor; and (ii) rock fragment size increasing toward the rim of the crater. To obtain a better understanding of the link between variation in seafloor morphology, rock size distribution, and other in situ processes, we compare our observations on the digital photo mosaic to bathymetry data and ROV visuals (e.g. vents and bacterial mats).

  11. Making a Submarine.

    ERIC Educational Resources Information Center

    Cornacchia, Deborah J.

    2002-01-01

    Describes Archimedes principle and why a ship sinks when it gets a hole in it. Suggests an activity for teaching the concept of density and water displacement through the construction of a simple submarine. Includes materials and procedures for this activity. (KHR)

  12. Bathymetry of the southwest flank of Mauna Loa Volcano, Hawaii

    USGS Publications Warehouse

    Chadwick, William W.; Moore, James G.; Fox, Christopher G.

    1994-01-01

    Much of the seafloor topography in the map area is on the southwest submarine flank of the currently active Mauna Loa Volcano. The benches and blocky hills shown on the map were shaped by giant landslides that resulted from instability of the rapidly growing volcano. These landslides were imagined during a 1986 to 1991 swath sonar program of the United States Hawaiian Exclusive Economic Zone, a cooperative venture by the U.S. Geological Survey and the British Institute of Oceanographic Sciences (Lipman and others, 1988; Moore and others, 1989). Dana Seamount (and probably also the neighboring Day Seamount) are apparently Cretaceous in age, based on paleomagnetic studies, and predate the growth of the Hawaiian Ridge volcanoes (Sager and Pringle, 1990).

  13. White submarine

    NASA Astrophysics Data System (ADS)

    While not everyone gets to live in a yellow submarine, the scientific community may get to have a decommissioned U.S. Navy nuclear submarine dedicated to it. The Sturgeon class of submarines, which scientists say are the ideal choice for the project, will be coming up for decommissioning in this next decade. So the time is ripe, scientists say. Two weeks ago, oceanographers, submarine specialists, marine biologists, and geophysicists, among others met at AGU headquarters in Washington to discuss how to get the project in the water. If all goes well, the project would be the "biggest thing that ever happened in ocean and Earth science," according to Lloyd Keigwin of the Woods Hole Oceanographic Institution, who convened the meeting. For example, the submarine could make many types of "compelling" research possible that can not be done now by other means, such as studies in the Arctic that may have significant bearing on global change research, Keigwin says. However, the imposing hurdles that the project must overcome are as big as the opportunities it offers. Foremost, there is a question as to who will pick up the tab for such an endeavor.

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

    NASA Astrophysics Data System (ADS)

    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

  15. Explorations of Mariana Arc Volcanoes Reveal New Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Embley, R. W.; Baker, E. T.; Chadwick, W. W., Jr.; Lupton, J. E.; Resing, J. A.; Massoth, G. J.; Nakamura, K.

    2004-01-01

    Some 20,000 km of volcanic arcs, roughly one-third the length of the global mid-ocean ridge (MOR) system, rim the western Pacific Ocean. Compared to 25 years of hydrothermal investigations along MORs, exploration of similar activity on the estimated ~600 submarine arc volcanoes is only beginning [Ishibashi and Urabe, 1995; De Ronde et al., 2003]. To help alleviate this under-sampling, the R/V T. G. Thompson was used in early 2003 (9 February to 5 March) to conduct the first complete survey of hydrothermal activity along 1200 km of the Mariana intra-oceanic volcanic arc. This region includes both the Territory of Guam and the Commonwealth of the Northern Mariana Islands. The expedition mapped over 50 submarine volcanoes with stunning new clarity (Figures 1 and 2) and found active hydrothermal discharge at 12 sites, including the southern back-arc site. This includes eight new sites along the arc (West Rota, Northwest Rota, E. Diamante, Zealandia Bank, Maug Caldera, Ahyi, Daikoku, and Northwest Eifuku) and four sites of previously known hydrothermal activity (Seamount X, Esmeralda, Kasuga 2, and Nikko) (Figures 1 and 2). The mapping also fortuitously provided a ``before'' image of the submarine flanks of Anatahan Island, which had its first historical eruption on 10 May 2003 (Figures 1 and 3).

  16. Ages of calderas, large explosive craters and active volcanoes in the Kuril-Kamchatka region, Russia

    NASA Astrophysics Data System (ADS)

    Braitseva, O. A.; Melekestsev, I. V.; Ponomareva, V. V.; Sulerzhitsky, L. D.

    1995-12-01

    The ages of most of calderas, large explosive craters and active volcanoes in the Kuril-Kamchatka region have been determined by extensive geological, geomorphological, tephrochronological and isotopic geochronological studies, including more than 600 14C dates. Eight ‘Krakatoa-type’ and three ‘Hawaiian-type’ calderas and no less than three large explosive craters formed here during the Holocene. Most of the Late Pleistocene Krakatoa-type calderas were established around 30 000 40 000 years ago. The active volcanoes are geologically very young, with maximum ages of about 40 000 50 000 years. The overwhelming majority of recently active volcanic cones originated at the very end of the Late Pleistocene or in the Holocene. These studies show that all Holocene stratovolcanoes in Kamchatka were emplaced in the Holocene only in the Eastern volcanic belt. Periods of synchronous, intensified Holocene volcanic activity occurred within the time intervals of 7500 7800 and 1300 1800 14C years BP.

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

    USGS Publications Warehouse

    Neal, Christina A.; Lockwood, John P.

    2003-01-01

    This report consists of a large map sheet and a pamphlet. The map shows the geology, some photographs, description of map units, and correlation of map units. The pamphlet gives the full text about the geologic map. The area covered by this map includes parts of four U.S. Geological Survey 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.

  18. A Scientific Excursion: Volcanoes.

    ERIC Educational Resources Information Center

    Olds, Henry, Jr.

    1983-01-01

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

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

    USGS Publications Warehouse

    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.

  20. 2008 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2011-01-01

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

  1. 2007 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2011-01-01

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

  2. Dueling Volcanoes: How Activity Levels At Kilauea Influence Eruptions At Mauna Loa

    NASA Astrophysics Data System (ADS)

    Trusdell, F.

    2011-12-01

    The eruption of Kilauea at Pu`u `O`o is approaching its 29th anniversary. During this time, Mauna Loa has slowly inflated following its most recent eruption in 1984. This is Mauna Loa's longest inter-eruptive interval observed in HVO's 100 years of operation. When will the next eruption of Mauna Loa take place? Is the next eruption of Mauna Loa tied to the current activity at Kilauea? Historically, eruptive periods at Kilauea and Mauna Loa volcanoes appear to be inversely correlated. In the past, when Mauna Loa was exceptionally active, Kilauea Volcano was in repose, recovery, or in sustained lava lake activity. Swanson and co-workers (this meeting) have noted that explosive activity on Kilauea, albeit sporadic, was interspersed between episodes of effusive activity. Specifically, Swanson and co-workers note as explosive the time periods between 300 B.C.E.-1000 C.E and 1500-1800 C.E. They also point to evidence for low magma supply to Kilauea during these periods and few flank eruptions. During the former explosive period, Mauna Loa was exceedingly active, covering approximately 37% of its surface or 1882 km2, an area larger than Kilauea. This period is also marked by summit activity at Mauna Loa sustained for 300 years. In the 1500-1800 C.E. period, Mauna Loa was conspicuously active with 29 eruptions covering an area of 446 km2. In the late 19th and early 20th century, Kilauea was dominated by nearly continuous lava-lake activity. Meanwhile Mauna Loa was frequently active from 1843 C.E. to 1919 C.E., with 24 eruptions for an average repose time of 3.5 years. I propose that eruptive activity at one volcano may affect eruptions at the other, due to factors that impact magma supply, volcanic plumbing, and flank motion. This hypothesis is predicated on the notion that when the rift zones of Kilauea, and in turn its mobile south flank, are active, Mauna Loa's tendency to erupt is diminished. Kilauea's rift zones help drive the south flank seaward, in turn, as Mauna

  3. 1996 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Neal, Christina A.; McGimsey, Robert G.

    1997-01-01

    During 1996, the Alaska Volcano Observatory (AVO) responded to eruptive activity, anomalous seismicity, or suspected volcanic activity at 10 of the approximately 40 active volcanic centers in the state of Alaska. As part of a formal role in KVERT (the Kamchatkan Volcano Eruption Response Team), AVO staff also disseminated information about eruptions and other volcanic unrest at six volcanic centers on the Kamchatka Peninsula and in the Kurile Islands, Russia.

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

    USGS Publications Warehouse

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

    2008-01-01

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

  5. Geothermal activity and energy of the Yakedake volcano, Gifu-Nagano, Japan

    SciTech Connect

    Iriyama, Jun

    1996-12-31

    The temperature of the most active solfatara in the summit crater of the Yakedake volcano (altitude 2,455 m Gifu-Nagano, Japan) was 92.2 and 129.4{degrees}C in September 1995 and in October 1994, respectively. The temperature of solfatara in the northern summit dome at an altitude of 2,240 to 2,270 m ranged from 68.2 to 92.5{degrees}C in September 1995. The water sample from a crater pond, Shoga-ike, located on the summit, showed a pH and electrical conductivity of 4.38 and 42.2 {mu}S/cm in October 1991, 4.35 and 42.4 {mu}S/cm in September 1992, 4.11 and 76.6 {mu}S/cm in October 1994, and 4.30 and 45.1 {mu}S/cm in September 1995, respectively. In 1960, the water sample from the same pond showed the pH and electrical conductivity of 3.7 and 80.8 {mu}S/cm, respectively. Although the values of pH and electrical conductivity in 1994 approached to the values at the volcano`s pre-eruption in 1960, the eruption in the summit dome did not occur in 1995. However, a large steam explosion occurred in the Nakanoyu area of the southeastern Mountainside of the volcano. The geothermal energy within the summit dome at an altitude of 2,050 to 2,455 m of the Yakedake volcano is calculated, using new data, to be about 4.8 x 10{sup 17} J, which represents a thermal power output of 5.1 x 10{sup 2} MW{sub th} averaged over 30 yrs.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Contact Lenses on Submarines

    DTIC Science & Technology

    2014-09-26

    NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY SUBMARINE BASE, GROTON, CONN. REPORT NUMBER 1048 CONTACT LENSES ON SUBMARINES... CONTACT LENSES ON SUBMARINES by James F. Socks, CDR, MSC, USN NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY REPORT NUMBER 1048 NAVAL MEDICAL RESEARCH...DRSCHLAB Approved for public release; distribution unlimited SUMMARY PAGE PROBLEM To determine the feasibility of wearing contact lenses aboard

  8. The Activity Of The Colima Volcano From 1999 To The 2003

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nuñez-Cornu, F.; Reyes-Davila, G.; Diaz-Torres, J.

    2004-12-01

    The Colima Volcano has shown intense activity since the 10th of February 1999. This explosive activity of 1999 and 2000 generated an elliptical crater of 260 x 265 m, which began to be filled in by a Dome from October 2001, at February 2002 the volume of the Dome was of approximately 2x106 m3 spreading over the edges of the crater and starting to flow during the following 11 months, in this period small lobes formed on the flanks of the volcano. Constants landslides originated in these lobes filled ravines of San Antonio, El Cordovan, El Muerto, El Cafesito and Atenquique (subsequent to the earthquake of January of the 2003) with non consolidated materials, increasing the hazard of lahares during the rainy season. Beginning February 2003 the explosive activity increased, most significantly from April to August, when the plumes reached heights over 2000 meters above the crater, occasionally small pyroclastic flows were observed. The explosive events continue to date. We mapped the most significant morphological changes produced at the summit by the activity described, using three photogrammetric flights conducted by INEGI (2003) and CARTODATA (2002 and 2003). These were data complemented by a very large number of photographs taken on helicopter flights undertaken during these months. Both the photographs and the digital mapping have provided detailed information to quantify the geomorphologic evolution of the superior section of the volcano, in the course of the last five years.

  9. Analysis of the seismicity activity of the volcano Ceboruco, Nayarit, Mexico

    NASA Astrophysics Data System (ADS)

    Rodriguez-Ayala, N. A.; Nunez-Cornu, F. J.; Escudero, C. R.; Zamora-Camacho, A.; Gomez, A.

    2014-12-01

    The Ceboruco is a stratovolcano is located in the state of Nayarit,Mexico (104 ° 30'31 .25 "W, 21 ° 7'28 .35" N, 2280msnm). This is an volcano active, as part of the Trans-Mexican Volcanic Belt, Nelson (1986) reports that it has had activity during the last 1000 years has averaged eruptions every 125 years or so, having last erupted in 1870, currently has fumarolic activity. In the past 20 years there has been an increase in the population and socio-economic activities around the volcano (Suárez Plascencia, 2013); which reason the Ceboruco study has become a necessity in several ways. Recent investigations of seismicity (Rodríguez Uribe et al., 2013) have classified the earthquakes in four families Ceboruco considering the waveform and spectral features. We present analysis included 57 days of seismicity from March to October 2012, in the period we located 97 events with arrivals of P and S waves clear, registered in at least three seasons, three components of the temporal network Ceboruco volcano.

  10. Seismicity at Uturuncu Volcano, Bolivia: Volcano-Tectonic Earthquake Swarms Triggered by the 2010 Maule, Chile Earthquake and Non-Triggered Background Activity

    NASA Astrophysics Data System (ADS)

    Christensen, D. H.; Chartrand, Z. A.; Jay, J.; Pritchard, M. E.; West, M. E.; McNutt, S. R.

    2010-12-01

    We find that the 270 ky dormant Uturuncu Volcano in SW Bolivia exhibits relatively high rates of shallow, volcano-tectonic seismicity that is dominated by swarm-like activity. We also document that the 27 February 2010 Mw 8.8 Maule, Chile earthquake triggered an exceptionally high rate of seismicity in the seconds to days following the main event. Although dormant, Uturuncu is currently being studied due to its large-scale deformation rate of 1-2 cm/yr uplift as revealed by InSAR. As part of the NASA-funded Andivolc project to investigate seismicity of volcanoes in the central Andes, a seismic network of 15 stations (9 Mark Products L22 short period and 6 Guralp CMG40T intermediate period sensors) with an average spacing of about 10 km was installed at Uturuncu from April 2009 to April 2010. Volcano-tectonic earthquakes occur at an average rate of about 3-4 per day, and swarms of 5-60 events within a span of minutes to hours occur a few times per month. Most of these earthquakes are located close to the summit at depths near and above sea level. The largest swarm occurred on 28 September 2009 and consisted of 60 locatable events over a time span of 28 hours. The locations of volcano-tectonic earthquakes at Uturuncu are oriented in a NW-SE trend, which matches the dominant orientation of regional faults and suggests a relationship between the fault system at Uturuncu and the regional tectonics of the area; a NW-SE trending fault beneath Uturuncu may serve to localize stresses that are accumulating over the broad area of uplift. Based on automated locations, the maximum local magnitude of these events is approximately M = 4 and the average magnitude is approximately M = 2. An initial estimate of the b-value is about b = 1.2. The Mw 8.8 Maule earthquake on 27 February 2010 triggered hundreds of local volcano-tectonic events at Uturuncu. High-pass filtering of the long period surface waves reveals that the first triggered events occurred with the onset of the Rayleigh

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-02-19

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

  13. Seismic activity related to the degassing of the Gorely volcano (Kamchatka)

    NASA Astrophysics Data System (ADS)

    Abramenkov, S. S.; Shapiro, N.; Koulakov, I.; Abkadyirov, I.; Frank, W.; Jakovlev, A.

    2015-12-01

    We analyzed continuous seismic records from a temporary network of 21 broadband seismograph that we installed in Gorely volcano (Kamchatka, Russia) between August 2013 and August 2014. During the studied period, the activity of Gorely was characterized by a sustained gas emission. We developed a source scanning algorithm based on summation of seismogram envelopes to automatically detect seismic events characterized by emerging signals without clear arrivals of P or S waves. With the help of this method, we detected and located numerous events originated from the vicinity of the main crater and caused by the volcano degassing. We then studied variations in spatio-temporal distribution of this seismic emission to characterize the evolution of the volcanic activity.

  14. Repeated remobilisation of submarine landslide debris on an active subduction margin interpreted from multibeam bathymetry and multichannel seismic data

    NASA Astrophysics Data System (ADS)

    Mountjoy, J. J.; Barnes, P. M.; McKean, J.; Pettinga, J. R.

    2008-12-01

    EM300 multibeam and multichannel seismic data reveal a 230 square kilometre submarine landslide complex which exhibits many of the characteristic features of equivalent terrestrial creeping earthflow complexes. Slope failures are sourced from the shelf edge/upper slope of the Poverty Bay reentrant on the active Hikurangi subduction margin of New Zealand where tectonic deformation, via major thrust faults with slip rates of c. 3-4 mm/yr, exerts a controlling influence on seafloor physiography. Individual landslides within this submarine complex are up to 14 km long over a vertical elevation drop of 700 m. Debris streams are in excess of 2 km wide with a debris thickness of 100 m. While multibeam data is limited to c. 10 m resolution, the scale of submarine landslide features allows us to resolve internal debris detail equivalent to terrestrial landslide examples using terrestrial techniques (e.g. airborne lidar). DEM derivative surface roughness techniques are employed to delineate the geomorphic expression of features including active and abandoned lateral shears, and contractional and extensional deformation of the landslide debris. From these interpretations multiple internal failures are recognised along the length of the landslide debris. Debris deformation is also imaged in high fold multichannel seismic data and correlated to the imaged surface geomorphic features, providing insight into the failure mechanics of the landslides. Failures initiate and evolve within the quasi-stable prograding sediment wedge built onto the upper slope during lowstand sealevels. Landslides within the greater complex are at different stages of development providing information on their spatial and temporal evolution headward and laterally along the transition from shelf to upper slope margin. We infer that failures are triggered and evolve in response to sealevel rise, and/or the frequent occurrence large earthquakes along the margin.

  15. Shallow water submarine hydrothermal activity - A case study in the assessment of ocean acidification and fertilization

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Yoshida, K.; Hagiwara, T.; Nagao, K.; Kusakabe, M.; Wang, B.; Chen, C. A.

    2012-12-01

    Most natural Shallow Water submarine Hydrothermal activates (SWH) along coastlines are related to hydrothermal eruptions involving heating of groundwater with the volcanic gas. These SWHs supply nutrients such as phosphorus and micro nutrients like iron to the euphotic zone, contributing to the overall natural fertility and primary productivity of coastal waters. However, SWHs also have a negative effect, dispersing toxic materials such as mercury and arsenic, and affecting the acidification of the surrounding waters. In this study, we evaluate the impact of "iron supply" and "ocean acidification" on the primary production in a coastal marine environment, at a SWH area discovered off Gueshandao Island, northeast Taiwan. In the past three years, expeditions were conducted and observations made around this SWH site. Divers, small boats and a research vessel (R/V OR1, Ocean University National Taiwan) were used to survey successively larger areas around the site. Some of the results obtained are as follows. Hydrothermal vents are located in a hilly terrain rich with hot spring water with gas erupting intermittently. There are two types of vents, roughly divided by color, yellow hot spring water with higher temperature >110 degC ejected from sulfur chimneys of various sizes, and colorless water with lower temperature ~80 degC ejected directly from the crevices of the andesitic bedrock. Natural sulfur solidifying in the mouth of a small chimney was captured by a video camera, and explosions were also observed at intervals of a few minutes. Sediment, sand and particles of sulfur were deposited on the sides to a radius of about 50 m condensing around the chimney. The bottom type changes from sand/particles to outcrop/rock away from the vents. Moreover, gas samples were collected from the vents; the ratios of gas concentrations (N2/Ar) and isotopic composition of noble gas (3He/4He) suggest that these volcanic gases are mantle-derived. Hydrothermal fluid with high p

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

    PubMed

    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.

  17. Recent turbidity current activity in sediment-starved submarine canyons (Northwestern Gulf of St. Lawrence, Eastern Canada)

    NASA Astrophysics Data System (ADS)

    Normandeau, Alexandre; Lajeunesse, Patrick; St-Onge, Guillaume; Bourgault, Daniel; Neumeier, Urs

    2016-04-01

    Submarine canyons are known to be main conduits for the transport of sediments to deep-sea basins, mostly by turbidity currents. Turbidity currents flowing in submarine canyons are mostly triggered by hyperpycnal flows, small to large slope failures and advection of shelf sediment offshore. In these contexts, sediment supply is necessary to maintain canyon activity over time. In 2007, a high-resolution mapping of small-scale submarine canyons offshore Pointe-des-Monts (NW Gulf of St. Lawrence, Eastern Canada) revealed a series of incisions characterized by the presence of numerous confined crescentic bedforms. The repeat mapping of the canyons in 2012 and 2015 revealed that the bedforms migrated upslope, indicating that they are cyclic steps produced by supercritical flows. Surprisingly, the comparison of multibeam surveys did not show any evidence of slope failures that could have triggered the turbidity currents responsible for recent bedform migration. Additionally, the rocky shores and coastal shelf do not supply sediments to these canyons, thus excluding turbidity current triggers such as advection of shelf sediments or hyperpycnal flows. In this context, we suggest that hydrodynamic processes are responsible for suspending in-situ sediments, which then may flow as turbidity currents when density of the water-sediment mixture is high enough. ADCPs deployed for 3,5 months during the summer of 2015 revealed along-canyon currents following tidal cycles with speeds up to 0.4 m/s, which were not strong enough to produce bedform migration. Therefore, the currents responsible for bedforms occur during infrequent events or during winter conditions, which both require longer instrument time-series to be observed.

  18. Ground survey of active Central American volcanoes in November - December 1973

    NASA Technical Reports Server (NTRS)

    Stoiber, R. E. (Principal Investigator); Rose, W. I., Jr.

    1974-01-01

    The author has identified the following significant results. Thermal anomalies at two volcanoes, Santiaguito and Izalco, have grown in size in the past six months, based on repeated ground survey. Thermal anomalies at Pacaya volcano have became less intense in the same period. Large (500 m diameter) thermal anomalies exist at 3 volcanoes presently, and smaller scale anomalies are found at nine other volcanoes.

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

    PubMed

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

    2013-10-30

    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.

  20. Autonomous thermal camera system for monitoring the active lava lake at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Peters, N.; Oppenheimer, C.; Kyle, P.

    2014-02-01

    In December 2012, the Mount Erebus Volcano Observatory installed a thermal infrared camera system to monitor the volcano's active lava lake. The new system is designed to be autonomous, and capable of capturing images of the lava lake continuously throughout the year. This represents a significant improvement over previous systems which required the frequent attention of observatory researchers and could therefore only be operated during a few weeks of the annual field campaigns. The extreme environmental conditions at the summit of Erebus pose significant challenges for continuous monitoring equipment, and a custom-made system was the only viable solution. Here we describe the hardware and software of the new system in detail and report on a publicly available online repository where data will be archived. Aspects of the technical solutions we had to find in order to overcome the challenges of automating this equipment may be relevant in other environmental science domains where remote instrument operation is involved.

  1. Autonomous thermal camera system for monitoring the active lava lake at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Peters, N.; Oppenheimer, C.; Kyle, P.

    2013-10-01

    In December 2012, the Mount Erebus Volcano Observatory installed a thermal infrared camera system to monitor the volcano's active lava lake. The new system is designed to be autonomous, and capable of capturing images of the lava lake continuously throughout the year. This represents a significant improvement over previous systems which required the frequent attention of observatory researchers and could therefore only be operated during a few weeks of the annual field campaigns. The extreme environmental conditions at the summit of Erebus pose significant challenges for continuous monitoring equipment, and a custom made system was the only viable solution. Here we describe the hardware and software of the new system in detail and report on a publicly-available online repository where data will be archived. Aspects of the technical solutions we had to find in order to overcome the challenges of automating this equipment may be relevant in other environmental science domains where remote instrument operation is involved.

  2. Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2008-01-01

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

  3. Review of eruptive activity at Tianchi volcano, Changbaishan, northeast China: implications for possible future eruptions

    NASA Astrophysics Data System (ADS)

    Wei, Haiquan; Liu, Guoming; Gill, James

    2013-04-01

    One of the largest explosive eruptions in the past several thousand years occurred at Tianchi volcano, also known as Changbaishan, on the China-North Korea border. This historically active polygenetic central volcano consists of three parts: a lower basaltic shield, an upper trachytic composite cone, and young comendite ash flows. The Millennium Eruption occurred between 938 and 946 ad, and was preceded by two smaller and chemically different rhyolitic pumice deposits. There has been at least one additional, small eruption in the last three centuries. From 2002 to 2005, seismicity, deformation, and the helium and hydrogen gas contents of spring waters all increased markedly, causing regional concern. We attribute this event to magma recharge or volatile exhalation or both at depth, followed by two episodes of addition of magmatic fluids into the overlying aquifer without a phreatic eruption. The estimated present magma accumulation rate is too low by itself to account for the 2002-2005 unrest. The most serious volcanic hazards are ash eruption and flows, and lahars. The available geological information and volcano monitoring data provide a baseline for comprehensive assessment of future episodes of unrest and possible eruptive activity.

  4. Passive vs. active degassing modes at an open-vent volcano (Stromboli, Italy)

    NASA Astrophysics Data System (ADS)

    Tamburello, G.; Aiuppa, A.; Kantzas, E. P.; McGonigle, A. J. S.; Ripepe, M.

    2012-12-01

    We report here on a UV-camera based field experiment performed on Stromboli volcano during 7 days in 2010 and 2011, aimed at obtaining the very first simultaneous assessment of all the different forms (passive and active) of SO2 release from an open-vent volcano. Using the unprecedented spatial and temporal resolution of the UV camera, we obtained a 0.8 Hz record of the total SO2 flux from Stromboli over a timeframe of ∼14 h, which ranged between 0.4 and 1.9 kg s-1 around a mean value of 0.7 kg s-1 and we concurrently derived SO2 masses for more than 130 Strombolian explosions and 50 gas puffs. From this, we show erupted SO2 masses have a variability of up to one order of magnitude, and range between 2 and 55 kg (average ∼20 kg), corresponding to a time integrated flux of 0.05±0.01 kg s-1. Our experimental constraints on individual gas puff mass (0.03-0.42 kg of SO2, averaging 0.19 kg) are the first of their kind, equating to an emission rate ranging from 0.02 to 0.27 kg s-1. On this basis, we conclude that puffing is two times more efficient than Strombolian explosions in the magmatic degassing process, and that active degassing (explosions+puffing) accounts for ∼23% (ranging from 10% to 45%) of the volcano's total SO2 flux, e.g., passive degassing between the explosions contributes the majority (∼77%) of the released gas. We furthermore integrate our UV camera gas data for the explosions and puffs, with independent geophysical data (infrared radiometer data and very long period seismicity), to offer key and novel insights into the degassing dynamics within the shallow conduit systems of this open-vent volcano.

  5. 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

    USGS Publications Warehouse

    Davies, A.G.; Keszthelyi, L.; McEwen, A.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 ??m) 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. ?? 2011 by the American Geophysical Union.

  6. 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

    USGS Publications Warehouse

    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.

  7. Io’s active volcanoes during the New Horizons era: Insights from New Horizons imaging

    NASA Astrophysics Data System (ADS)

    Rathbun, J. A.; Spencer, J. R.; Lopes, R. M.; Howell, R. R.

    2014-03-01

    In February 2007, the New Horizons spacecraft flew by the Jupiter system, obtaining images of Io, the most volcanically active body in the Solar System. The Multicolor Visible Imaging Camera (MVIC), a four-color (visible to near infrared) camera, obtained 17 sets of images. The Long-Range Reconnaissance Imager (LORRI), a high-resolution panchromatic camera, obtained 190 images, including many of Io eclipsed by Jupiter. We present a complete view of the discrete point-like emission sources in all images obtained by these two instruments. We located 54 emission sources and determined their brightnesses. These observations, the first that observed individual Ionian volcanoes on short timescales of seconds to minutes, demonstrate that the volcanoes have stable brightnesses on these timescales. The active volcanoes Tvashtar (63N, 124W) and E. Girru (22N, 245W) were observed by both LORRI and MVIC, both in the near-infrared (NIR) and methane (CH4) filters. Tvashtar was additionally observed in the red filter, which allowed us to calculate a color temperature of approximately 1200 K. We found that, with some exceptions, most of the volcanoes frequently active during the Galileo era continued to be active during the New Horizons flyby. We found that none of the seven volcanoes observed by New Horizons multiple times over short timescales showed substantial changes on the order of seconds and only one, E. Girru exhibited substantial variation over minutes to days, increasing by 25% in just over an hour and decreasing by a factor of 4 over 6 days. Observations of Tvashtar are consistent with a current eruption similar to previously observed eruptions and are more consistent with the thermal emission of a lava flow than the fire fountains inferred from the November 1999 observations. These data also present new puzzles regarding Ionian volcanism. Since there is no associated surface change or low albedo feature that could be identified nearby, the source of the emission from

  8. Boron-rich mud volcanoes of the Black Sea region: modern analogues to ancient sea-floor tourmalinites associated with Sullivan-type Pb-Zn deposits?

    USGS Publications Warehouse

    Slack, J.F.; Turner, R.J.W.; Ware, P.L.G.

    1998-01-01

    Large submarine mud volcanoes in the abyssal part of the Black Sea south of the Crimean Peninsula are similar in many respects to synsedimentary mud volcanoes in the Mesoproterozoic Belt-Purcell basin. One of the Belt-Purcell mud volcanoes directly underlies the giant Sullivan Pb-Zn-Ag deposit in southeastern British Columbia. Footwall rocks to the Sullivan deposit comprise variably tourmalinized siltstone, conglomerate, and related fragmental rock; local thin pyrrhotite-rich and spessartine-quartz beds are interpreted as Fe and Fe-Mn exhalites, respectively. Analogous Fe- and Mn-rich sediments occur near the abyssal Black Sea mud volcanoes. Massive pyrite crusts and associated carbonate chimneys discovered in relatively shallow waters (~200 m depth) west of the Crimean Peninsula indicate an active sea-floor-hydrothermal system. Subaerial mud volcanoes on the Kerch and Taman Peninsulas (~100 km north of the abyssal mud volcanoes) contain saline thermal waters that locally have very high B contents (to 915 mg/L). These data suggest that tourmalinites might be forming in or near submarine Black Sea mud volcanoes, where potential may also exist for Sullivan-type Pb-Zn mineralization.

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

    NASA Astrophysics Data System (ADS)

    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

  10. 1997 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Wallace, Kristi L.

    1999-01-01

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

  11. Hanging canyons of Haida Gwaii, British Columbia, Canada: Fault-control on submarine canyon geomorphology along active continental margins

    NASA Astrophysics Data System (ADS)

    Harris, Peter T.; Barrie, J. Vaughn; Conway, Kim W.; Greene, H. Gary

    2014-06-01

    Faulting commonly influences the geomorphology of submarine canyons that occur on active continental margins. Here, we examine the geomorphology of canyons located on the continental margin off Haida Gwaii, British Columbia, that are truncated on the mid-slope (1200-1400 m water depth) by the Queen Charlotte Fault Zone (QCFZ). The QCFZ is an oblique strike-slip fault zone that has rates of lateral motion of around 50-60 mm/yr and a small convergent component equal to about 3 mm/yr. Slow subduction along the Cascadia Subduction Zone has accreted a prism of marine sediment against the lower slope (1500-3500 m water depth), forming the Queen Charlotte Terrace, which blocks the mouths of submarine canyons formed on the upper slope (200-1400 m water depth). Consequently, canyons along this margin are short (4-8 km in length), closely spaced (around 800 m), and terminate uniformly along the 1400 m isobath, coinciding with the primary fault trend of the QCFZ. Vertical displacement along the fault has resulted in hanging canyons occurring locally. The Haida Gwaii canyons are compared and contrasted with the Sur Canyon system, located to the south of Monterey Bay, California, on a transform margin, which is not blocked by any accretionary prism, and where canyons thus extend to 4000 m depth, across the full breadth of the slope.

  12. Present-day submarine hydrothermal activity in the Taupo-Rotorua Zone (Bay of Plenty, New Zealand)

    SciTech Connect

    Osipenko, A.B.; Egorov, Yu.O.; Fazlullin, S.M.; Gavrilenko, G.M.; Shul`kin, V.I.; Chertkova, L.V.

    1994-09-01

    We made detailed descriptions of the structure and material composition of sedimentary and water columns in the vicinity of active submarine hydrothermal activity in the southern part of the Bay of Plenty (North Island, New Zealand). Geophysical methods revealed that the hydrothermal system is confined to a tectonically distinct zone with a sedimentary cover characterized by complex structure. Chemical and mineralogical investigations confirmed that the activity of underwater vents exerts no substantial regional influence on the composition and features of ore mineralization in these formations. It is shown that essentially hydrothermal formations distinguishable within areas of otherwise monotypic sediments directly coincide with zones of hydrothermal discharge in the ocean floor. The absence of pronounced hydrothermal anomalies, together with the presence of {open_quotes}tongues{close_quotes} of anomalous concentrations of water-soluble gases suggests that the discharges are primarily hydrothermal in character.

  13. Volcano acoustic activity associated with the eruption of Mt. Usu, 2000 - Mud-pool Strombolian -

    NASA Astrophysics Data System (ADS)

    Aoyama, H.; Oshima, H.; Maekawa, T.

    2001-12-01

    There was intense acoustic activity associated with the eruption of Mount Usu, which began on March 31, 2000. Repeating phreatic explosions generated many isolated infrasonic signals, which were observed at plural acoustic stations. During the periods when acoustic activity was high, infrasonic pulses as many as 200 were identified every 10 minutes. Source location of infrasonic signals could be well identified from the records of the low frequency microphone network. Two active craters, Nishiyama craterlets and Konpirayama craterlets, are clearly distinguished by sound source determination analysis though distance between them is around 1 km. To investigate the transition of acoustic activity from April to June, 2000, we contrive a method to detect arrival and amplitude of infrasonic signals automatically. The number of automatically identified infrasonic signals exceeds 1.46 million during three months. It seems that there is a good correlation between acoustic activity and seismic signal amplitude. Patterns of acoustic activity and infrasonic pulse shapes observed at Usu volcano are very similar to those of observed at Stromboli volcano, Italy. We name the acoustic activity accompanied with phreatic explosion that scatters a lot of clods `mud-pool Strombolian type'. Phreatic explosion excites not only infrasonic pulse but also seismic signal observed before the arrival of infrasonic pulse. Existence of Rayleigh wave phase with large amplitude suggests that the seismic wave is excited at a shallow part.

  14. Stratigraphic constraints for explosive activity in the past 100 ka at Etna Volcano, Italy

    NASA Astrophysics Data System (ADS)

    Coltelli, Mauro; Del Carlo, Paola; Vezzoli, Luigina

    2000-08-01

    The pyroclastic deposits of Etna have been correlated over the whole volcanic edifice for the first time, allowing the construction of a continuous record of tephra-producing events, which extends from approximately 100 ka to the Present. In this interval, five main periods of explosive activity have been identified: (a) 100-ka strombolian to subplinian activity; (b) 80- to 100-ka plinian benmoreitic activity; (c) 16- to 80-ka strombolian to subplinian from basaltic to mugearitic activity; (d) 15.5- to 15-ka plinian benmoreitic activity accompanying the caldera-forming eruptions of the Ellittico Volcano; and (e) the most recent 13-ka basaltic explosive activity of strombolian and subplinian type of the present edifice that also includes the 122-B.C. plinian eruption. This study results in a semi-quantitative and in some cases quantitative definition of the intensity and chronology of the explosive activity at Etna. Moreover, this work gives a new significance to the volcanic hazards of Etna, a volcano generally considered to be the site of gentle effusive eruptions.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1984-05-01

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

  17. Tectonically active sediment dispersal system in SW Taiwan margin with emphasis on the Gaoping (Kaoping) Submarine Canyon

    NASA Astrophysics Data System (ADS)

    Yu, Ho-Shing; Chiang, Cheng-Shing; Shen, Su-Min

    2009-03-01

    The sediment dispersal system in southwestern Taiwan margin consists of two main parts: the subaerial drainage basin and the offshore receiving marine basin. In plan view, this sediment dispersal system can be further divided into five geomorphic units: (1) the Gaoping (formerly spelled Kaoping) River drainage basin, (2) the Gaoping (Kaoping) Shelf, (3) the Gaoping (Kaoping) Slope, (4) the Gaoping (Kaoping) Submarine Canyon and (5) the Manila Trench in the northernmost South China Sea. The Gaoping River drainage basin is a small (3250 km 2), tectonically active and overfilled foreland basin, receiving sediments derived from the uprising Central Range of Taiwan with a maximum elevation of 3952 m. The Gaoping Submarine Canyon begins at the mouth of the Gaoping River, crosses the narrow Gaoping Shelf (~ 10 km) and the Gaoping Slope, and finally merges into the northern termination of the Manila Trench over a distance of ~ 260 km. The SW Taiwan margin dispersal system is characterized by a direct river-canyon connection with a narrow shelf and frequent episodic sediment discharge events in the canyon head. In a regional source to sink scheme, the Gaoping River drainage basin is the primary source area, the Gaoping Shelf being the sediment bypass zone and the Gaoping Slope being the temporary sink and the Manila Trench being the ultimate sink of the sediment from the Taiwan orogen. It is inferred from seismic data that the outer shelf and upper slope region can be considered as a line source for mass wasting deposits delivered to the lower Gaoping Slope where small depressions between diapiric ridges are partially filled with sediment or are empty. At present, recurrent hyperpycnal flows during the flood seasons are temporarily depositing sediments mainly derived from the Gaoping River in the head of the Gaoping Submarine Canyon. On the decadal and century timescales, sediments temporarily stored in the upper reach are removed over longer timescales probably by

  18. Insights into the 2011-2012 submarine eruption off the coast of El Hierro (Canary Islands, Spain) from statistical analyses of earthquake activity

    NASA Astrophysics Data System (ADS)

    Ibáñez, J. M.; De Angelis, S.; Díaz-Moreno, A.; Hernández, P.; Alguacil, G.; Posadas, A.; Pérez, N.

    2012-08-01

    The purpose of this work is to gain insights into the 2011-2012 eruption of El Hierro (Canary Islands) by mapping the evolution of the seismic b-value. The El Hierro seismic sequence offers a rather unique opportunity to investigate the process of reawakening of an oceanic intraplate volcano after a long period of repose. The 2011-2012 eruption is a submarine volcanic event that took place about 2 km off of the southern coast of El Hierro. The eruption was accompanied by an intense seismic swarm and surface manifestations of activity. The earthquake catalogue during the period of unrest includes over 12 000 events, the largest with magnitude 4.6. The seismic sequence can be grouped into three distinct phases, which correspond to well-separated spatial clusters and distinct earthquake regimes. The estimated b-value is of 1.18 ± 0.03, and a magnitude of completeness of 1.3, for the entire catalogue. B is very close to 1.0, which indicates completeness of the earthquake catalogue with only minor departures from the linearity of Gutenberg-Richter frequency-magnitude distribution. The most straightforward interpretation of this result is that the seismic swarm reached its final stages, and no additional large magnitude events should be anticipated, similarly to what one would expect for non-volcanic earthquake sequences. The results, dividing the activity in different phases, illustrate remarkable differences in the estimate of b-value during the early and late stages of the eruption. The early pre-eruptive activity was characterized by a b-value of 2.25. In contrast, the b-value was 1.25 during the eruptive phase. Based on our analyses, and the results of other studies, we propose a scenario that may account for the observations reported in this work. We infer that the earthquakes that occurred in the first phase reflect magma migration from the upper mantle to crustal depths. The area where magma initially intruded into the crust, because of its transitional nature

  19. Chemical evolution of thermal springs at Arenal Volcano, Costa Rica: Effect of volcanic activity, precipitation, seismic activity, and Earth tides

    NASA Astrophysics Data System (ADS)

    López, D. L.; Bundschuh, J.; Soto, G. J.; Fernández, J. F.; Alvarado, G. E.

    2006-09-01

    Arenal Volcano in NW Costa Rica, Central America has been active during the last 37 years. However, only relatively low temperature springs have been identified on its slopes with temperatures less than around 60 °C. The springs are clustered on the NE and NW slopes of the volcano, close to contacts between the recent and older volcanic products or at faults that intercept the volcano. This volcano is located in a rain forest region with annual rainfall averaging around 5 m. During the last 15 years, the temperature and chemical composition of 4 hot springs and 2 cold springs have been monitored approximately every 3 months. In addition, two more thermal sites were identified recently and sampled, as well as two boreholes located on a fault NE of the volcano. Scatter plots of chemical species such as Cl and B suggest that the waters in these discharges belong to the same aquifer with a saline end member similar to Río Tabacón at the beginning of the study period (1990) and the deeper borehole (B-2) in 2004. The waters of Quebrada Bambú and Quebrada Fría represent a more dilute end member. Both long-term (over the 15 years) and short-term or seasonal decreases in concentration and steady or decreasing temperature are noted in NW springs. Springs located at the NE show increasing temperatures and ion concentrations, except for bicarbonate that has decreased in concentration for all the springs. This behavior is likely associated with a shallow source for the solutes and heat for this aquifer. To the NW the early lavas and pyroclastic flows have been cooling down, decreasing the contribution of leaching products to the infiltrating waters. To the NE, pyroclastic flows to the N during the last decade are contributing increasing concentrations of solutes and heat throughout water infiltration and circulation within the faults and the surficial drainage that has a NE regional trend. For the short-term or seasonal variations, concentrations of chemical constituents

  20. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2001-01-01

    An Expedition Two crewmember aboard the International Space Station (ISS) captured this overhead look at the smoke and ash regurgitated from the erupting volcano Mt. Etna on the island of Sicily, Italy. At an elevation of 10,990 feet (3,350 m), the summit of the Mt. Etna volcano, one of the most active and most studied volcanoes in the world, has been active for a half-million years and has erupted hundreds of times in recorded history.

  1. Monitoring eruption activity from temporal stress changes at Mt. Ontake volcano, Japan

    NASA Astrophysics Data System (ADS)

    Terakawa, T.; Kato, A.; Yamanaka, Y.; Maeda, Y.; Horikawa, S.; Matsuhiro, K.; Okuda, T.

    2015-12-01

    On 27 September 2014, Mt. Ontake in Japan produced a phreatic (steam type) eruption with a Volcanic Explosivity Index value of 2 after being dormant for seven years. The local stress field around volcanoes is the superposition of the regional stress field and stress perturbations related to volcanic activity. Temporal stress changes over periods of weeks to months are generally attributed to volcanic processes. Here we show that monitoring temporal changes in the local stress field beneath Mt. Ontake, using focal mechanism solutions of volcano-tectonic (VT) earthquakes, is an effective tool for assessing the state of volcanic activity. We estimated focal mechanism solutions of 157 VT earthquakes beneath Mt. Ontake from August 2014 to March 2015, assuming that the source was double-couple. Pre-eruption seismicity was dominated by normal faulting with east-west tension, whereas most post-eruption events were reverse faulting with east-west compression. The misfit angle between observed slip vectors and those derived theoretically from the regional (i.e., background) stress pattern is used to evaluate the deviation of the local stress field, or the stress perturbation related to volcanic activity. The moving average of misfit angles tended to exceed 90° before the eruption, and showed a marked decrease immediately after the eruption. This indicates that during the precursory period the local stress field beneath Mt. Ontake was rotated by stress perturbations caused by the inflation of magmatic/hydrothermal fluids. Post-eruption events of reverse faulting acted to shrink the volcanic edifice after expulsion of volcanic ejecta, controlled by the regional stress field. The misfit angle is a good indicator of the state of volcanic activity. The monitoring method by using this indicator is applicable to other volcanoes and may contribute to the mitigation of volcanic hazards.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  3. What drives centuries-long polygenetic scoria cone activity at Barren Island volcano?

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu

    2014-12-01

    Barren Island in the Andaman Sea is an active mafic stratovolcano, which had explosive and effusive eruptions, followed by caldera formation, in prehistoric time (poorly dated). A scoria cone within the caldera, marking volcanic resurgence, was active periodically from 1787 to 1832 (the historic eruptions). Since 1991, the same scoria cone has produced six eruptions, commonly including lava flows. Links between Barren Island's eruptions and giant earthquakes (such as the 26 December 2004 Great Sumatra megathrust earthquake) have been suggested, though there is no general correlation between them. The ≥ 227-year-long activity of the scoria cone, named here Shanku ("cone"), is normally driven by purely magmatic processes. I present a "source to surface" model for Barren Island and Shanku, including the source region, deeper and shallow magma chambers, volcanotectonics, dyking from magma chambers, and eruptions and eruptive style as controlled by crustal stresses, composition and volatile content. Calculations show that dykes ~ 0.5 m thick and a few hundred meters long, originating from shallow-level magma chambers (~ 5 km deep), are suitable feeders of the Shanku eruptions. Shanku, a polygenetic scoria cone (at least 13 eruptions since 1787), has three excellent analogues, namely Anak Krakatau (40 eruptions since 1927), Cerro Negro (23 eruptions since 1850), and Yasur (persistent activity for the past hundreds of years). This is an important category of volcanoes, gradational between small "monogenetic" scoria cones and larger "polygenetic" volcanoes.

  4. Source mechanism of very-long-period signals accompanying dome growth activity at Merapi volcano, Indonesia

    USGS Publications Warehouse

    Hidayat, D.; Chouet, B.; Voight, B.; Dawson, P.; Ratdomopurbo, A.

    2002-01-01

    Very-long-period (VLP) pulses with period of 6-7s, displaying similar waveforms, were identified in 1998 from broadband seismographs around the summit crater. These pulses accompanied most of multiphase (MP) earthquakes, a type of long-period event locally defined at Merapi Volcano. Source mechanisms for several VLP pulses were examined by applying moment tensor inversion to the waveform data. Solutions were consistent with a crack striking ???70?? and dipping ???50?? SW, 100m under the active dome, suggest pressurized gas transport involving accumulation and sudden release of 10-60 m3 of gas in the crack over a 6s interval.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. 1995 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Neal, Christina A.

    1996-01-01

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

  7. Very Long Period Seismicity Accompanying Increasing Shallower Activity at Cotopaxi Volcano

    NASA Astrophysics Data System (ADS)

    Arias, G.; Molina Polania, C. I.; Ruiz, M. C.; Kumagai, H.; Hernandez, S.; Plain, M.; Mothes, P. A.; Yepez, M.; Barrington, C.; Hidalgo, S.

    2015-12-01

    Cotopaxi is an andesitic stratovolcano, located in the highland region of Ecuador, which renewed its activity in April 2015, showing an increased number of volcano-tectonic (VT), long-period (LP), very long period events (VLP), and tremors. The VLP events were recorded in several episodes between 2002 and 2014, and have been interpreted as volumetric changes due to the release of gas and subsequent pressure drop and recovery in the magma intrusion. The two peaks of VLP seismicity in June 2002 and April 2015 preceded an increase of surficial activity (fumarolic increase) and the deformation data during those episodes suggested a small intrusion of magma beneath the volcano.Using polarization analysis, we found that most of these events were located at 2-3 km depth beneath the volcano summit, while the deformation data suggests the intrusion is deeper (5-10 km deep). Using tiltmeter data, Mogi point source modelling on successive periods of inflation and deflation show a significant shallowing of sources since the end of May 2015, matching the recent very large spike in SO2 emissions (~3000 t/d). From mid-February until the gas emission spikes in May 2015, Mogi source modelling has indicated inflation/deflation events at 11 to 10 km depth, having shallowed to a depth of between 8 and 7 km after the SO2 emission increase. Shallow source volumes suggested by deformation indicate values of 4 - 31x106 m3, with the most recent, most shallow inflation currently at 8x106 m3.

  8. Water chemistry of lakes related to active and inactive Mexican volcanoes

    NASA Astrophysics Data System (ADS)

    Armienta, María Aurora; Vilaclara, Gloria; De la Cruz-Reyna, Servando; Ramos, Silvia; Ceniceros, Nora; Cruz, Olivia; Aguayo, Alejandra; Arcega-Cabrera, Flor

    2008-12-01

    Water chemistry of crater lakes, maars and water reservoirs linked to some Mexican volcanoes within and outside the Mexican Volcanic Belt has been determined for several years and examined regarding environmental and volcanic factors. All the analyzed lakes are relatively small with a maximum depth of 65 m, and are located in regions with different climates, from semi-arid to very humid, with altitudes ranging from 100 to more than 4000 m a.s.l. Crater lakes in active volcanoes (El Chichón, Popocatépetl) have very low pH, moderate to high temperatures and major ion concentrations varying with the level of volcanic unrest. Lakes in sub-arid and temperate-arid regions (like maars in Puebla and Guanajuato states) show high alkalinity and pH, with bicarbonate/carbonate, chloride, sodium and magnesium as predominant ions. Lakes located in humid climates (Central Michoacán and Veracruz state) have low mineralization and near-neutral pH values. In general, conservative dissolved ions and conductivity appear to be mostly controlled by precipitation/evaporation and by the ionic concentration of groundwater inputs. Calcium, magnesium, sulfate concentrations and pH are strongly influenced by volcanic-rock or volcanic gas interactions with water. The influence of low-level volcanic activity on crater lakes may be obscured by water-rock interactions, and climatic factors. One of the aims of this paper is to define the relative influence of these factors searching for a reference frame to recognize the early volcanic precursors in volcano-related lakes.

  9. Spontaneous Potential Anomalies on Active Volcanoes: New Time and Spatial Series from Masaya, Telica, and Cerro Negro, Nicaragua

    NASA Astrophysics Data System (ADS)

    Lehto, H.; Pearson, S.; Connor, C.; Sanford, W.; Saballos, A.

    2006-12-01

    Considerable effort worldwide has gone into monitoring heat and mass transfer at active volcanoes because such information may provide clues about changes in volcanic activity and impending eruptions. Here we present new time and spatial series of spontaneous potential (SP) anomalies from Masaya and Telica volcanoes, and spatial series collected at Cerro Negro volcano. Our primary purpose is to investigate correlations between more easily and cheaply monitored SP and CO2 gas flux, measured by an infrared CO2 analysis system. SP data were collected using nonpolarizing Pb-PbCL2 electrodes that we constructed following the approach of Petiau. Mapping at both Masaya, and Cerro Negro reveals broad correlations between SP anomalies and CO2 flux through soils. In addition, we monitored temperature, barometric pressure, and rainfall at one minute intervals from May-August, 2006 at Masaya and Telica volcanoes. During this period it is clear that SP responds to changes in volcanic activity, with transient anomalies of 75 mV as well as atmospheric forcing due to rainfall, producing anomalies of 56 mV and related phenomena. Preliminary lab experiments provide further details of the electrokinetic origin of these SP anomalies. Our preliminary work supports the idea that large and inexpensive networks of electrodes might track changes in SP anomalies associated with changes in mass flow at active volcanoes.

  10. Dendrogeomorphic reconstruction of lahar activity and triggers: Shiveluch volcano, Kamchatka Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Salaorni, E.; Stoffel, M.; Tutubalina, O.; Chernomorets, S.; Seynova, I.; Sorg, A.

    2017-01-01

    Lahars are highly concentrated, water-saturated volcanic hyperconcentrated flows or debris flows containing pyroclastic material and are a characteristic mass movement process on volcanic slopes. On Kamchatka Peninsula (Russian Federation), lahars are widespread and may affect remote settlements. Historical records of past lahar occurrences are generally sparse and mostly limited to events which damaged infrastructure on the slopes or at the foot of volcanoes. In this study, we present a tree-ring-based reconstruction of spatiotemporal patterns of past lahar activity at Shiveluch volcano. Using increment cores and cross sections from 126 Larix cajanderi trees, we document 34 events covering the period AD 1729-2012. Analyses of the seasonality of damage in trees reveal that 95% of all lahars occurred between October and May and thus point to the predominant role of the sudden melt of the snow cover by volcanic material. These observations suggest that most lahars were likely syn-eruptive and that lahar activity is largely restricted to periods of volcanic activity. By contrast, rainfall events do not seem to play a significant role in lahar triggering.

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

    NASA Astrophysics Data System (ADS)

    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

  12. Large landslides from oceanic volcanoes

    USGS Publications Warehouse

    Holcomb, R.T.; Searle, R.C.

    1991-01-01

    Large landslides are ubiquitous around the submarine flanks of Hawaiian volcanoes, and GLORIA has also revealed large landslides offshore from Tristan da Cunha and El Hierro. On both of the latter islands, steep flanks formerly attributed to tilting or marine erosion have been reinterpreted as landslide headwalls mantled by younger lava flows. These landslides occur in a wide range of settings and probably represent only a small sample from a large population. They may explain the large volumes of archipelagic aprons and the stellate shapes of many oceanic volcanoes. Large landslides and associated tsunamis pose hazards to many islands. -from Authors

  13. Acoustic Recordings of Strombolian and Subplinian Activity at Shishaldin Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Caplan-Auerbach, J.; McNutt, S. R.; Vergniolle, S.; Boichu, M.

    2002-05-01

    New data from a pressure sensor provide a detailed perspective on the 1999 eruption of Shishaldin volcano, Alaska. The eruption was well monitored by a 6-station seismic network and frequent satellite passes, but visual observations were minimal. To refine our interpretation of the 1999 eruption we investigate acoustic data recorded on a pressure sensor 6.5 km north of Shishaldin. Three types of acoustic signals were identified, representing different types of eruptive behavior. On April 19, 1999 the pressure sensor recorded a monotonic (2-3 Hz) hum that grew in amplitude for more than 13 hours. At 19:35 UTC on April 19, the humming signal abruptly ended and seismic tremor amplitude increased dramatically. Four minutes later, a broadband (1-15 Hz) signal was recorded on both the pressure sensor and the seismometers, suggesting the onset of the main Subplinian phase. The Subplinian phase appears in the acoustic record as a 50-min broadband signal, over which several low-frequency bursts are superimposed. The final acoustic phase detected by the pressure sensor was a series of discrete pulses, interpreted to be strong Strombolian gas explosions. The strongest explosions, recorded on April 23rd were associated with a small, ash-poor plume and strong seismic tremor. In time series, these events are similar to gas explosions observed at other volcanoes such as Stromboli and Karymsky, but are of lower frequency (1-2 Hz) and are 1-2 orders of magnitude (up to 60 Pa at 6.5 km) larger. Waveform modeling allows us to constrain the size and overpressure of the bubbles, as well as the amount of gas and magma released during the Strombolian phase of the eruption. The acoustic data may be used to investigate the change from Strombolian activity to Subplinian, and back to Strombolian. The 1999 Shishaldin eruption shows that pressure sensors can serve as an excellent complement to traditional means of monitoring remote volcanoes.

  14. Arctic Submarine Slope Stability

    NASA Astrophysics Data System (ADS)

    Winkelmann, D.; Geissler, W.

    2010-12-01

    Submarine landsliding represents aside submarine earthquakes major natural hazard to coastal and sea-floor infrastructure as well as to coastal communities due to their ability to generate large-scale tsunamis with their socio-economic consequences. The investigation of submarine landslides, their conditions and trigger mechanisms, recurrence rates and potential impact remains an important task for the evaluation of risks in coastal management and offshore industrial activities. In the light of a changing globe with warming oceans and rising sea-level accompanied by increasing human population along coasts and enhanced near- and offshore activities, slope stability issues gain more importance than ever before. The Arctic exhibits the most rapid and drastic changes and is predicted to change even faster. Aside rising air temperatures, enhanced inflow of less cooled Atlantic water into the Arctic Ocean reduces sea-ice cover and warms the surroundings. Slope stability is challenged considering large areas of permafrost and hydrates. The Hinlopen/Yermak Megaslide (HYM) north of Svalbard is the first and so far only reported large-scale submarine landslide in the Arctic Ocean. The HYM exhibits the highest headwalls that have been found on siliciclastic margins. With more than 10.000 square kilometer areal extent and app. 2.400 cubic kilometer of involved sedimentary material, it is one of the largest exposed submarine slides worldwide. Geometry and age put this slide in a special position in discussing submarine slope stability on glaciated continental margins. The HYM occurred 30 ka ago, when the global sea-level dropped by app. 50 m within less than one millennium due to rapid onset of global glaciation. It probably caused a tsunami with circum-Arctic impact and wave heights exceeding 130 meters. The HYM affected the slope stability field in its neighbourhood by removal of support. Post-megaslide slope instability as expressed in creeping and smaller-scaled slides are

  15. Origin and distribution of thiophenes and furans in gas discharges from active volcanoes and geothermal systems.

    PubMed

    Tassi, Franco; Montegrossi, Giordano; Capecchiacci, Francesco; Vaselli, Orlando

    2010-03-31

    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 C(2)-C(20) 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 C(4)H(8)O, 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.

  16. Development of an automatic volcanic ash sampling apparatus for active volcanoes

    NASA Astrophysics Data System (ADS)

    Shimano, Taketo; Nishimura, Takeshi; Chiga, Nobuyuki; Shibasaki, Yoshinobu; Iguchi, Masato; Miki, Daisuke; Yokoo, Akihiko

    2013-12-01

    We develop an automatic system for the sampling of ash fall particles, to be used for continuous monitoring of magma ascent and eruptive dynamics at active volcanoes. The system consists of a sampling apparatus and cameras to monitor surface phenomena during eruptions. The Sampling Apparatus for Time Series Unmanned Monitoring of Ash (SATSUMA-I and SATSUMA-II) is less than 10 kg in weight and works automatically for more than a month with a 10-kg lead battery to obtain a total of 30 to 36 samples in one cycle of operation. The time range covered in one cycle varies from less than an hour to several months, depending on the aims of observation, allowing researchers to target minute-scale fluctuations in a single eruptive event, as well as daily to weekly trends in persistent volcanic activity. The latest version, SATSUMA-II, also enables control of sampling parameters remotely by e-mail commands. Durability of the apparatus is high: our prototypes worked for several months, in rainy and typhoon seasons, at windy and humid locations, and under strong sunlight. We have been successful in collecting ash samples emitted from Showa crater almost everyday for more than 4 years (2008-2012) at Sakurajima volcano in southwest Japan.

  17. Relationship between fumarole gas composition and eruptive activity at Galeras Volcano, Colombia

    SciTech Connect

    Fischer, T.P.; Williams, S.N.; Arehart, G.B.; Sturchio, N.C.

    1996-06-01

    Forecasting volcanic eruptions is critical to the mitigation of hazards for the millions of people living dangerously close to active volcanoes. Volcanic gases collected over five years from Galeras Volcano, Colombia, and analyzed for chemical and isotopic composition show the effects of long-term degassing of the magma body and a gradual decline in sulfur content of the gases. In contrast, short-term (weeks), sharp variations are the precursors to explosive eruptions. Selective absorption of magmatic SO{sub 2} and HCl due to interaction with low-temperature geothermal waters allows the gas emissions to become dominated by CO{sub 2}. Absorption appears to precede an eruption because magmatic volatiles are slowed or retained by a sealing carapace, reducing the total flux of volatiles and allowing the hydrothermal volatiles to dominate gas emissions. Temporal changes in gas compositions were correlated with eruptive activity and provide new evidence bearing on the mechanism of this type of `pneumatic` explosive eruptions. 18 refs., 5 figs.

  18. Carbonado-like diamond from the Avacha active volcano in Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Kaminsky, Felix V.; Wirth, Richard; Anikin, Leonid P.; Morales, Luiz; Schreiber, Anja

    2016-11-01

    In addition to a series of finds of diamond in mafic volcanic and ultramafic massive rocks in Kamchatka, Russia, a carbonado-like diamond aggregate was identified in recent lavas of the active Avacha volcano. This aggregate differs from 'classic carbonado' by its location within an active volcanic arc, well-formed diamond crystallites, and cementing by Si-containing aggregates rather than sintering. The carbonado-like aggregate contains inclusions of Mn-Ni-Si-Fe alloys, native β-Mn, tungsten and boron carbides, which are uncommon for both carbonado and monocrystalline diamonds. Mn-Ni-Si-Fe alloys, trigonal W2C and trigonal B4C are new mineral species that were not previously found in the natural environment. The formation of the carbonado-like diamond aggregate started with formation at 850-1000 °C of tungsten and boron carbides, Mn-Ni-Si-Fe alloys and native β-Mn, which were used as seeds for the subsequent crystallization of micro-sized diamond aggregate. In the final stage, the diamond aggregate was cemented by amorphous silica, tridymite, β-SiC, and native silicon. The carbonado-like aggregate was most likely formed at near-atmospheric pressure conditions via the CVD mechanism during the course or shortly after one of the volcanic eruption pulses of the Avacha volcano. Volcanic gases played a great role in the formation of the carbonado-like aggregate.

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

    PubMed Central

    Tassi, Franco; Montegrossi, Giordano; Capecchiacci, Francesco; Vaselli, Orlando

    2010-01-01

    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. PMID:20480029

  20. Monitoring Monitoring Evolving Activity at Popocatepetl Volcano, Mexico, 2000-2001

    NASA Astrophysics Data System (ADS)

    Martin-DelPozzo, A.; Aceves, F.; Bonifaz, R.; Humberto, S.

    2001-12-01

    After 6 years of small eruptions, activity at Mexico's 5,452m high Popocatepetl Volcano in central Mexico, peaked in the December 2000-January 2001 eruptions. Precursors included an important increase in seismicity as well as in magmatic components of spring water and small scale deformation which resulted in growth of a new crater dome from January 16 on. Evacuation of the towns nearest the volcano over Christmas was decided because of the possibility of pyroclastic flows. During the previous years, crater dome growth, contraction and explosive clearing has dominated the activity. The January 22 eruption produced an eruption column approximately 17km high with associated pyroclastic flows. Ejecta was composed of both basic and evolved scoria and pumice and dome lithics. A large proportion of the juvenile material was intermediate between these 2 endmenbers (59-63percent SiO2 and 3.5 to 5.5 MgO) consistent with a small basic pulse entering a more evolved larger batch of magma. The January eruption left a large pit which has been partially infilled by another crater dome this August 2001.

  1. How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

    NASA Astrophysics Data System (ADS)

    Corbi, F.; Rivalta, E.; Pinel, V.; Maccaferri, F.; Bagnardi, M.; Acocella, V.

    2015-12-01

    Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we show with numerical models that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Galápagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observations. We then develop a general model for the stress state at volcanic edifices with calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control: 1) the shallow accumulation of magma in stacked sills, consistently with observations; 2) the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

  2. Seismic image of a CO2 reservoir beneath a seismically active volcano

    USGS Publications Warehouse

    Julian, B.R.; Pitt, A.M.; Foulger, G.R.

    1998-01-01

    Mammoth Mountain is a seismically active volcano 200 000 to 50 000 years old, situated on the southwestern rim of Long Valley caldera, California. Since 1989 it has shown evidence of unrest in the form of earthquake swarms (Hill et al. 1990), volcanic 'long-period' earthquakes (Pitt and Hill 1994), increased output of magmatic 3He (Sorey et al. 1993) and the emission of about 500 tonnes day-1 of CO2 (Farrar et al. 1995; Hill 1996; M. Sorey, personal communication, 1997) which has killed trees and poses a threat to human safety. Local-earthquake tomography shows that in mid-1989 areas of subsequent tree-kill were underlain by extensive regions where the ratio of the compressional and shear elastic-wave speeds Vp/VS was about 9% lower than in the surrounding rocks. Theory (Mavko and Mukerji 1995), experiment (Ito, DeVilbiss and Nur 1979) and experience at other geothermal/volcanic areas (Julian et al. 1996) and at petroleum reservoirs (Harris et al. 1996) indicate that Vp/VS is sensitive to pore-fluid compressibility, through its effect on Vp. The observed Vp/VS anomaly is probably caused directly by CO2, and seismic Vp/VS tomography is thus a promising tool for monitoring gas concentration and movement in volcanoes, which may in turn be related to volcanic activity.

  3. Santorini Volcano

    USGS Publications Warehouse

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

    1999-01-01

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

  4. Systematic Survey of the Kermadec-Tonga Intra-oceanic arc Between 1999 and 2004: a Significant Source of Diverse Submarine Hydrothermal Emissions

    NASA Astrophysics Data System (ADS)

    de Ronde, C. E.; Massoth, G. J.; Baker, E. T.; Lupton, J. E.; Arculus, R. J.; Wright, I. C.; Stoffers, P.; Ishibashi, J.; Walker, S. L.; Greene, R. R.; Faure, K.; Takai, K.

    2004-12-01

    The 1999 NZAPLUME cruise was the first of several expeditions to systematically locate, and chemically characterise, submarine hydrothermal vents associated with arc volcanoes of the southern part the Kermadec-Tonga intra-oceanic arc system. This was followed by the 2002 NZAPLUME II and 2004 NZAPLUME III cruises to the mid- and northern-sections of the Kermadec arc, respectively, and the 2001 TELVE cruise to the southern part of the Tonga (Tofua) arc. Combined, ˜1,800 km of this arc system have been mapped, including ˜60 major volcanoes and numerous subordinate volcanic edifices, making this the longest continuous stretch of intra-oceanic arc to be surveyed for hydrothermal emissions. Most of the volcanoes are simple cones although ˜25% are caldera volcanoes with their compositions ranging from basalt through rhyo-dacite. Results from the NZAPLUME I and II cruises show 16 of the 26 major volcanoes surveyed are hydrothermally active, while 7 of 19 are active along the Tongan section of the arc, a ˜50% frequency of venting. Depths to venting range from ˜120 m to ˜1,650 m. Chemical analysis of the hydrothermal plumes shows a large range in composition, including different compositions for plumes from vent sites at the same volcano, with indications locally of a magmatic fluid component. An expedition in Oct./Nov. 2004 by the deep-sea submersible Shinkai 6500 will enable vent sites at Brothers and Healy volcanoes to be mapped and mineralization, animals to be sampled.

  5. Submarine Volcanic Morphology of Santorini Caldera, Greece

    NASA Astrophysics Data System (ADS)

    Nomikou, P.; Croff Bell, K.; Carey, S.; Bejelou, K.; Parks, M.; Antoniou, V.

    2012-04-01

    Santorini volcanic group form the central part of the modern Aegean volcanic arc, developed within the Hellenic arc and trench system, because of the ongoing subduction of the African plate beneath the European margin throughout Cenozoic. It comprises three distinct volcanic structures occurring along a NE-SW direction: Christianna form the southwestern part of the group, Santorini occupies the middle part and Koloumbo volcanic rift zone extends towards the northeastern part. The geology of the Santorini volcano has been described by a large number of researchers with petrological as well as geochronological data. The offshore area of the Santorini volcanic field has only recently been investigated with emphasis mainly inside the Santorini caldera and the submarine volcano of Kolumbo. In September 2011, cruise NA-014 on the E/V Nautilus carried out new surveys on the submarine volcanism of the study area, investigating the seafloor morphology with high-definition video imaging. Submarine hydrothermal vents were found on the seafloor of the northern basin of the Santorini caldera with no evidence of high temperature fluid discharges or massive sulphide formations, but only low temperature seeps characterized by meter-high mounds of bacteria-rich sediment. This vent field is located in line with the normal fault system of the Kolumbo rift, and also near the margin of a shallow intrusion that occurs within the sediments of the North Basin. Push cores have been collected and they will provide insights for their geochemical characteristics and their relationship to the active vents of the Kolumbo underwater volcano. Similar vent mounds occur in the South Basin, at shallow depths around the islets of Nea and Palaia Kameni. ROV exploration at the northern slopes of Nea Kameni revealed a fascinating underwater landscape of lava flows, lava spines and fractured lava blocks that have been formed as a result of 1707-1711 and 1925-1928 AD eruptions. A hummocky topography at

  6. The structure of the Campanian Plain and the activity of the Neapolitan volcanoes (Italy)

    NASA Astrophysics Data System (ADS)

    Scandone, Roberto; Bellucci, Francesca; Lirer, Lucio; Rolandi, Giuseppe

    1991-08-01

    The central Campanian Plain is dominated by the structural depression of Acerra whose origin is tectonic, but may have been enlarged and further depressed after the eruption of the Campanian Ignimbrite (42-25 ka). The deposits of the Campanian Ignimbrite are possibly the results of multiple eruptions with huge pyroclastic deposits that covered all the Campanian Plain. The more recent activity of Vesuvius, Campi Flegrei and Procida occurred on the borders of Acerra depression and resulted from a reactivation of regional faults after the Campanian Ignimbrite cycle. The activity of Vesuvius produced the building of a stratovolcano mostly by effusive and plinian explosive eruptions. The Campi Flegrei area, on the contrary, was dominated by the eruption of the Neapolitan Yellow Tuff at 12 ka that produced a caldera collapse of the Gulf of Pozzuoli. The caldera formation controlled the emplacement of the recent activity of Campi Flegrei and the new volcanoes were formed only within the caldera or along its rim.

  7. Early growth of Kohala volcano and formation of long Hawaiian rift zones

    USGS Publications Warehouse

    Lipman, P.W.; Calvert, A.T.

    2011-01-01

    Transitional-composition pillow basalts from the toe of the Hilo Ridge, collected from outcrop by submersible, have yielded the oldest ages known from the Island of Hawaii: 1138 ?? 34 to 1159 ?? 33 ka. Hilo Ridge has long been interpreted as a submarine rift zone of Mauna Kea, but the new ages validate proposals that it is the distal east rift zone of Kohala, the oldest subaerial volcano on the island. These ages constrain the inception of tholeiitic volcanism at Kohala, provide the first measured duration of tholeiitic shield building (???870 k.y.) for any Hawaiian volcano, and show that this 125-km-long rift zone developed to near-total length during early growth of Kohala. Long eastern-trending rift zones of Hawaiian volcanoes may follow fractures in oceanic crust activated by arching of the Hawaiian Swell in front of the propagating hotspot. ?? 2011 Geological Society of America.

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

    PubMed

    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.

  9. An Overview of Geodetic Volcano Research in the Canary Islands

    NASA Astrophysics Data System (ADS)

    Fernández, José; González, Pablo J.; Camacho, Antonio G.; Prieto, Juan F.; Brú, Guadalupe

    2015-11-01

    The Canary Islands are mostly characterized by diffuse and scattered volcanism affecting a large area, with only one active stratovolcano, the Teide-Pico Viejo complex (Tenerife). More than 2 million people live and work in the 7,447 km2 of the archipelago, resulting in an average population density three times greater than the rest of Spain. This fact, together with the growth of exposure during the past 40 years, increases volcanic risk with respect previous eruptions, as witnessed during the recent 2011-2012 El Hierro submarine eruption. Therefore, in addition to purely scientific reasons there are economic and population-security reasons for developing and maintaining an efficient volcano monitoring system. In this scenario geodetic monitoring represents an important part of the monitoring system. We describe volcano geodetic monitoring research carried out in the Canary Islands and the results obtained. We consider for each epoch the two main existing constraints: the level of volcanic activity in the archipelago, and the limitations of the techniques available at the time. Theoretical and observational aspects are considered, as well as the implications for operational volcano surveillance. Current challenges of and future perspectives in geodetic volcano monitoring in the Canaries are also presented.

  10. Recent uplift and hydrothermal activity at Tangkuban Parahu volcano, west Java, Indonesia

    USGS Publications Warehouse

    Dvorak, J.; Matahelumual, J.; Okamura, A.T.; Said, H.; Casadevall, T.J.; Mulyadi, D.

    1990-01-01

    Tangkuban Parahu is an active stratovolcano located 17 km north of the city of Bandung in the province west Java, Indonesia. All historical eruptive activity at this volcano has been confined to a complex of explosive summit craters. About a dozen eruptions-mostly phreatic events- and 15 other periods of unrest, indicated by earthquakes or increased thermal activity, have been noted since 1829. The last magmatic eruption occurred in 1910. In late 1983, several small phreatic explosions originated from one of the summit craters. More recently, increased hydrothermal and earthquake activity occurred from late 1985 through 1986. Tilt measurements, using a spirit-level technique, have been made every few months since February 1981 in the summit region and along the south and east flanks of the volcano. Measurements made in the summit region indicated uplift since the start of these measurements through at least 1986. From 1981 to 1983, the average tilt rate at the edges of the summit craters was 40-50 microradians per year. After the 1983 phreatic activity, the tilt rate decreased by about a factor of five. Trilateration surveys across the summit craters and on the east flank of the volcano were conducted in 1983 and 1986. Most line length changes measured during this three-year period did not exceed the expected uncertainty of the technique (4 ppm). The lack of measurable horizontal strain across the summit craters seems to contradict the several years of tilt measurements. Using a point source of dilation in an elastic half-space to model tilt measurements, the pressure center at Tangkuban Parahu is located about 1.5 km beneath the southern part of the summit craters. This is beneath the epicentral area of an earthquake swarm that occurred in late 1983. The average rate in the volume of uplift from 1981 to 1983 was 3 million m3 per year; from 1983 to 1986 it averaged about 0.4 million m3 per year. Possible causes for this uplift are increased pressure within a very

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Fiber Bragg grating strain sensors to monitor and study active volcanoes

    NASA Astrophysics Data System (ADS)

    Sorrentino, Fiodor; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvo; Giacomelli, Umberto; Grassi, Renzo; Maccioni, Enrico; Morganti, Mauro

    2016-04-01

    Stress and strain changes are among the best indicators of impending volcanic activity. In volcano geodesy, borehole volumetric strain-meters are mostly utilized. However, they are not easy to install and involve high implementation costs. Advancements in opto-electronics have allowed the development of low-cost sensors, reliable, rugged and compact, thus particularly suitable for field application. In the framework of the EC FP7 MED-SUV project, we have developed strain sensors based on the fiber Bragg grating (FBG) technology. In comparison with previous implementation of the FBG technology to study rock deformations, we have designed a system that is expected to offer a significantly higher resolution and accuracy in static measurements and a smooth dynamic response up to 100 Hz, implying the possibility to observe seismic waves. The system performances are tailored to suit the requirements of volcano monitoring, with special attention to power consumption and to the trade-off between performance and cost. Preliminary field campaigns were carried out on Mt. Etna (Italy) using a prototypal single-axis FBG strain sensor, to check the system performances in out-of-the-lab conditions and in the harsh volcanic environment (lack of mains electricity for power, strong diurnal temperature changes, strong wind, erosive ash, snow and ice during the winter time). We also designed and built a FBG strain sensor featuring a multi-axial configuration which was tested and calibrated in the laboratory. This instrument is suitable for borehole installation and will be tested on Etna soon.

  13. Vein networks in hydrothermal systems provide constraints for the monitoring of active volcanoes.

    PubMed

    Cucci, Luigi; Di Luccio, Francesca; Esposito, Alessandra; Ventura, Guido

    2017-12-01

    Vein networks affect the hydrothermal systems of many volcanoes, and variations in their arrangement may precede hydrothermal and volcanic eruptions. However, the long-term evolution of vein networks is often unknown because data are lacking. We analyze two gypsum-filled vein networks affecting the hydrothermal field of the active Lipari volcanic Island (Italy) to reconstruct the dynamics of the hydrothermal processes. The older network (E1) consists of sub-vertical, N-S striking veins; the younger network (E2) consists of veins without a preferred strike and dip. E2 veins have larger aperture/length, fracture density, dilatancy, and finite extension than E1. The fluid overpressure of E2 is larger than that of E1 veins, whereas the hydraulic conductance is lower. The larger number of fracture intersections in E2 slows down the fluid movement, and favors fluid interference effects and pressurization. Depths of the E1 and E2 hydrothermal sources are 0.8 km and 4.6 km, respectively. The decrease in the fluid flux, depth of the hydrothermal source, and the pressurization increase in E2 are likely associated to a magma reservoir. The decrease of fluid discharge in hydrothermal fields may reflect pressurization at depth potentially preceding hydrothermal explosions. This has significant implications for the long-term monitoring strategy of volcanoes.

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

    PubMed Central

    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

  15. Volcanic activity observed from continuous seismic records in the region of the Klyuchevskoy group of volcanoes

    NASA Astrophysics Data System (ADS)

    Shapiro, N.; Droznin, D.; Droznina, S.; Senyukov, S.; Chebrov, V.; Gordeev, E.; Frank, W.

    2014-12-01

    We analyze continuous seismic records from 18 permanent stations operated in vicinity of the Klyuchevskoy group of volcanos (Kamchatka, Russia) during the period between 2009 and 2014. We explore the stability of the inter-station cross-correlation to detect different periods of sustained emission from seismic energy. The main idea of this approach is that cross-correlation waveforms computed from a wavefield emitted by a seismic source from a fixed position remain stable during the period when this source is acting. The detected periods of seismic emission correspond to different episodes of activity of volcanoes: Klyuchevskoy, Tolbachik, Shiveluch, and Kizimen. For Klyuchevskoy and Tolbachik whose recent eruptions are mostly effusive, the detected seismic signals correspond to typical volcanic tremor, likely caused by degassing processes. For Shiveluch and Kizimen producing more silicic lavas, the observed seismic emission often consists of many repetitive long period (LP) seismic events that might be related to the extrusion of viscous magmas. We develop an approach for automatic detection of these individual LP events in order to characterize variations of their size and recurrence in time.

  16. Volcanic activity observed from continuous seismic records in the region of the Klyuchevskoy group of volcanoes

    NASA Astrophysics Data System (ADS)

    Shapiro, N.; Droznin, D.; Droznina, S.; Senyukov, S.; Chebrov, V.; Gordeev, E.; Frank, W.

    2015-12-01

    We analyze continuous seismic records from 18 permanent stations operated in vicinity of the Klyuchevskoy group of volcanos (Kamchatka, Russia) during the period between 2009 and 2014. We explore the stability of the inter-station cross-correlation to detect different periods of sustained emission from seismic energy. The main idea of this approach is that cross-correlation waveforms computed from a wavefield emitted by a seismic source from a fixed position remain stable during the period when this source is acting. The detected periods of seismic emission correspond to different episodes of activity of volcanoes: Klyuchevskoy, Tolbachik, Shiveluch, and Kizimen. For Klyuchevskoy and Tolbachik whose recent eruptions are mostly effusive, the detected seismic signals correspond to typical volcanic tremor, likely caused by degassing processes. For Shiveluch and Kizimen producing more silicic lavas, the observed seismic emission often consists of many repetitive long period (LP) seismic events that might be related to the extrusion of viscous magmas. We develop an approach for automatic detection of these individual LP events in order to characterize variations of their size and recurrence in time.

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

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

    Since the eruption which affected Quito in AD 1660, Guagua Pichincha has been considered a hazardous volcano. Based on field studies and twenty 14C dates, this paper discusses the eruptive activity of this volcano, especially that of the last 2000 years. Three major Plinian eruptions with substantial pumice discharge occurred in the 1st century, the 10th century, and in AD 1660. The ages of organic paleosols and charcoal from block-and-ash flow and fallout deposits indicate that these eruptions occurred near the end of 100 to 200 year-long cycles of discontinuous activity which was comprised of dome growth episodes and minor pumice fallouts. The first cycle took place from ~ AD 1 to 140. The second one developed during the 9th and 10th centuries, lasted 150-180 yr, and included the largest Plinian event, with a VEI of 5. The third, historic cycle, about 200 yr in duration, includes pyroclastic episodes around AD 1450 and AD 1500, explosive activity between AD 1566 and AD 1582, possible precursors of the 1660 eruption in the early decades of the 17th century, and finally the 1660 eruption (VEI 4). A fourth event probably occurred around AD 500, but its authenticity requires confirmation. The Plinian events occurred at the end of these cycles which were separated by repose periods of at least 300 yr. Older volcanic activity of similar type occurred between ~ 4000 and ~ 3000 yr BP. Because ash fallout and related mudflows represent a serious hazard for Quito's metropolitan area, the significance of the increasing phreatic activity observed from 1981 to 1998, and the 1999-2001 magmatic episode of dome growth and collapse are discussed. These probably represent a short step in a longer evolution which may result in a major Plinian event in the future decades or in the next century, comparable to that which occurred during the 1st, 10th, and 17th centuries.

  18. Subglacial melting associated with activity at Bárdarbunga volcano, Iceland, explored using numerical reservoir simulations

    NASA Astrophysics Data System (ADS)

    Reynolds, Hannah I.; Gudmundsson, Magnús T.; Högnadóttir, Thórdís

    2015-04-01

    Increased seismic activity was observed within the caldera of Bárdarbunga, a central volcano beneath Vatnajökull glacier, on 16 August 2014. The seismicity traced the path of a lateral dyke, initially propagating to the south east of the volcano, before changing course and continuing beyond the northern extent of the glacier. A short fissure eruption occurred at the site of the Holuhraun lavas on 29 August, lasting for approximately 5 hours and producing less than 1 million cubic meters of lava, before recommencing in earnest on 31 August with the large effusive eruption, which is still ongoing at the time of writing. The glacier surface has been monitored aerially since the onset of heightened seismic activity, and the caldera and dyke propagation path surveyed using radar profiling. Ice cauldrons are shallow depressions which form on the glacier surface due to basal melting, as a manifestation of heat flux from below; the melting ice acts as a calorimeter, allowing estimations of heat flux magnitude to be made. Several cauldrons were observed outside the caldera, two to the south east of Bárdarbunga, and three located above the path of the dyke under the Dyngjujökull outlet glacier. The cauldrons range in volume from approximately 0.001 km3 to 0.02 km3. We present time series data of the development and evolution of these cauldrons, with estimates of the heat flux magnitudes involved. The nature of the heat source required to generate the aforementioned cauldrons is not obvious and two scenarios are explored: 1) small subglacial eruptions; or 2) increased geothermal activity induced by the dyke intrusion. We investigate these scenarios using analytical and finite element modelling, considering the surface heat flux produced, and timescales and spatial extent of associated surface anomalies. A range of permeabilities has been explored. It is found that an intrusion of a dyke or sill into rocks where the groundwater is near or at the boiling point curve can

  19. 2005 Volcanic Activity in Alaska, Kamchatka, and the Kurile Islands: Summary of Events and Response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    2008-01-01

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

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

    USGS Publications Warehouse

    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.

  1. Chlorine isotopes of thermal springs in arc volcanoes for tracing shallow magmatic activity

    NASA Astrophysics Data System (ADS)

    Li, Long; Bonifacie, Magali; Aubaud, Cyril; Crispi, Olivier; Dessert, Céline; Agrinier, Pierre

    2015-03-01

    The evaluation of the status of shallow magma body (i.e., from the final intrusion stage, to quiescence, and back to activity), one of the key parameters that trigger and sustain volcanic eruptions, has been challenging in modern volcanology. Among volatile tracers, chlorine (Cl) uniquely exsolves at shallow depths and is highly hydrophilic. Consequently, Cl enrichment in volcanic gases and thermal springs has been proposed as a sign for shallow magmatic activities. However, such enrichment could also result from numerous other processes (e.g., water evaporation, dissolution of old chloride mineral deposits, seawater contamination) that are unrelated to magmatic activity. Here, based on stable isotope compositions of chloride and dissolved inorganic carbon, as well as previous published 3He/4He data obtained in thermal springs from two recently erupted volcanoes (La Soufrière in Guadeloupe and Montagne Pelée in Martinique) in the Lesser Antilles Arc, we show that the magmatic Cl efficiently trapped in thermal springs displays negative δ37Cl values (≤ - 0.65 ‰), consistent with a slab-derived origin but distinct from the isotope compositions of chloride in surface reservoirs (e.g. seawater, local meteoric waters, rivers and cold springs) displaying common δ37Cl values of around 0‰. Using this δ37Cl difference as an index of magmatic Cl, we further examined thermal spring samples including a 30-year archive from two thermal springs in Guadeloupe covering samples from its last eruption in 1976-1977 to 2008 and an island-wide sampling event in Martinique in 2008 to trace the evolution of magmatic Cl in the volcanic hydrothermal systems over time. The results show that magmatic Cl can be rapidly flushed out of the hydrothermal systems within <30 to 80 years after the eruption, much quicker than other volatile tracers such as CO2 and noble gases, which can exsolve at greater depths and constantly migrate to the surface. Because arc volcanoes often have well

  2. The preliminary results of new submarine caldera on the west of Kume-jima island, Central Ryukyu Arc, Japan

    NASA Astrophysics Data System (ADS)

    Harigane, Y.; Ishizuka, O.; Shimoda, G.; Sato, T.

    2014-12-01

    The Ryukyu Arc occurs between the islands of Kyushu and Taiwan with approximately 1200 km in the full length. This volcanic arc is caused by subduction of the Philippine Sea plate beneath the Eurasia Plate along the Ryukyu trench, and is composed of forearc islands, chains of arc volcanoes, and a back-arc rift called Okinawa Trough. The Ryukyu Arc is commonly divided into three segments (northern, central and southern) that bounded by the Tokara Strait and the Kerama Gap, respectively (e.g., Konishi 1965; Kato et al., 1982). Sato et al. (2014) mentioned that there is no active subaerial volcano in the southwest of Iotori-shima in the Central Ryukyu Arc whereas the Northern Ryukyu Arc (i.e., the Tokara Islands) has active frontal arc volcanoes. Therefore, the existence of volcanoes and volcanotectonic history of active volcanic front in the southwestern part of the Central Ryukyu Arc are still ambiguous. Detailed geophysical and geological survey was mainly conducted using R/V Kaiyou-maru No.7 during GK12 cruise operated by the Geological Survey of Japan/National Institute of Advanced Industrial Science and Technology, Japan. As a result, we have found a new submarine volcanic caldera on the west of Kume-jima island, where located the southwestern part of Central Ryukyu Arc. Here, we present (1) the bathymetrical feature of this new submarine caldera for the first time and (2) the microstructural and petrological observations of volcanic rocks (20 volcanic samples in 13 dredge sites) sampled from the small volcanic cones of this caldera volcano. The dredged samples from the caldera consist of mainly rhyolite pumice with minor andesites, Mn oxides-crust and hydrothermally altered rocks. Andesite has plagioclase, olivine and pyroxene phenocrysts. Key words: volcanic rock, caldera, arc volcanism, active volcanic front, Kume-jima island, Ryukyu Arc

  3. Observations of Active Submarine Groundwater Discharge on a Shallow Coastal Sea in Yucatan, Mexico

    NASA Astrophysics Data System (ADS)

    Marino, I.; Vera, I.; Enriquez, C.; Capurro, L.; Kantun, C.

    2008-12-01

    This contribution presents detailed measurements of fresh water fluxes from an energetic submarine groundwater discharge (SGD) located on the coastal ocean on Dzilam Bravo, Yucatan, Mexico. Due to the geologic characteristics of the site (karstic geology), inland groundwater flows through karstic conduits and exits at sea. Time series of fluxes measured by an acoustic velocimeter (VECTOR), temperature and salinity are correlated to the variability imposed by tides, currents, waves and rainfall. The contribution of SGD is a determining factor in the dynamics of marine ecosystems because it provides fresh water, nutrients, contaminants and other solutes. For this reason it is important to increase the knowledge about its dynamics and mixing processes that take place in these kind of environments. To study the spacial variability of thermohaline conditions, an area of 1 by 1 km (which includes five freshwater springs) was measured with a vessel towed CTD during drough and rainfall seasons. The results reveal that the flow conditions for the main spring (X'buya-Ha) is controlled by sea level variations, which include tides and weather effects. The outflow velocity is about 0.5 m/s during dry season when the discharge is weak, and about 3 m/s during periods of intense rainfall, when the discharge is strong. Also, it was noted that outflow direction changes as a result of high and low tides along a day. Results will be presented on the spatial influence as well, showing that the effect of the springs is very localised during high tide, but expands considerably during low tides.

  4. The Pulse of the Volcano: Discovery of Episodic Activity at Prometheus on Io

    NASA Technical Reports Server (NTRS)

    Davies, A. G.

    2003-01-01

    The temporal behaviour of thermal output from a volcano yields valuable clues to the processes taking place at and beneath the surface. Galileo Near Infrared Mapping Spectrometer (NIMS) data show that the ionian volcanoes Prometheus and Amirani have significant thermal emission in excess of nonvolcanic background emission in every geometrically appropriate NIMS observation. The 5 micron brightness of these volcanoes shows considerable variation from orbit to orbit. Prometheus in particular exhibits an episodicity that yields valuable constraints to the mechanisms of magma supply and eruption. This work is part of an on-going study to chart and quantify the thermal emission of Io's volcanoes, determine mass eruption rates, and note eruption style.

  5. Monitoring El Hierro submarine volcanic eruption events with a submarine seismic array

    NASA Astrophysics Data System (ADS)

    Jurado, Maria Jose; Molino, Erik; Lopez, Carmen

    2013-04-01

    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 2012 and was a reference also to follow the evolution of the seismic activity associated with the volcanic eruption. From the beginning of the eruption a geophone string was installed less than 2 km away from the new volcano, next to La Restinga village shore, 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. The analysis of the dataset using spectral techniques allows the characterization of the different phases of the eruption and the study of its dynamics. The correlation of the data analysis results with the observed sea surface activity (ash and lava emission and degassing) and also with the seismic activity recorded by the IGN field seismic monitoring system, allows the identification of different stages suggesting the existence of different signal sources during the volcanic eruption and also the posteruptive record of the degassing activity. The study shows that the high frequency capability of the geophone array allow the study of important features that cannot be registered by the standard seismic stations. The accumulative spectral amplitude show features related to eruptive changes.

  6. Icelandic Volcanoes Geohazard Supersite and FUTUREVOLC: role of interferometric synthetic aperture radar to identify renewed unrest and track magma movement beneath the most active volcanoes in Iceland

    NASA Astrophysics Data System (ADS)

    Parks, Michelle; Dumont, Stéphanie; Spaans, Karsten; Drouin, Vincent; Sigmundsson, Freysteinn; Hooper, Andrew; Michalczewska, Karolina; Ófeigsson, Benedikt

    2014-05-01

    FUTUREVOLC is an integrated volcano monitoring project, funded by the European Commission (FP7) and led by the University of Iceland and the Icelandic Meteorological Office (IMO). The project is a European collaborative effort, comprising 26 partners, aimed at integrating ground based and satellite observations for improved monitoring and evaluation of volcanic hazards. Iceland has also recently been declared a Geohazard Supersite by the Committee on Earth Observation Satellites, based on its propensity for relatively frequent eruptions and their potentially hazardous, long ranging effects. Generating a long-term time series of ground displacements is key to gaining a better understanding of sub-volcanic processes, including the detection of new melt and migration of magma within the crust. The focus of the FUTUREVOLC deformation team is to generate and interpret an extended time series of high resolution deformation measurements derived from InSAR observations, in the vicinity of the four most active volcanoes in Iceland: Grímsvötn, Katla, Hekla and Bárdarbunga. A comprehensive network of continuous deformation monitoring equipment, led by IMO and collaborators, is already deployed at these volcanoes, including GPS, tilt and borehole strainmeters. InSAR observations are complementary to field based measurements and their high spatial resolution assists in resolving the geometry and location of the source of the deformation. InSAR and tilt measurements at Hekla indicate renewed melt supply to a sub-volcanic reservoir after the last eruption in 2000. Recent deformation studies utilising data spanning this eruption, have provided insight into the shallow plumbing system which may explain the large reduction in eruption repose interval following the 1970 eruption. Although InSAR and GPS observations at Katla volcano (between 2001 and 2009) suggest no indication of magma induced deformation outside the ice-cap, it is possible that a small flood at Mýrdalsjökull in

  7. Geochemical Evidence for Submarine Hydrothermal Activity in the Gulf of Aden, Northwestern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Gamo, T.; Hasumoto, H.; Okamura, K.; Hatanaka, H.; Mori, M.; Chinen, M.; Tanaka, J.; Komatsu, D.; Tamaki, K.; Fujimoto, H.; Tsunogai, U.; Kouzuma, F.; Hirota, A.

    2001-12-01

    We searched for hydrothermal plumes along spreading axes in the Gulf of Aden, between 45\\deg36'E and 52\\deg42'E, using a CTD multi-water sampling system, mapping water column distributions of light transmission and chemical tracers (Mn, Fe, CH4 etc.) in December 2000 and January 2001. In addition to water sampling for chemical analysis, an in-situ chemical analyzer GAMOS was attached to the CTD-system to conduct tow-yo observations. We found typical hydrothermal plumes (anomalies of light transmission and chemical tracers) at 600-800 m depth over twin peak seamounts (60 miles southeast of Aden) which may be hot spot volcanoes associated with the Afar mantle plume. Strong light transmission anomalies imply the existence of black smoker fluids. The maximum concentrations of Mn, Fe, and CH4 are 46 nM, 251 nM, and 15 nM, respectively. An estimated \\delta13C(CH4) value for an endmember fluid of approximately -15\\permil indicates magmatic CH4 with little contribution of CH4 from organic material decomposition in sediments.

  8. Broadband seismic monitoring of active volcanoes using deterministic and stochastic approaches

    NASA Astrophysics Data System (ADS)

    Kumagai, H.; Nakano, M.; Maeda, T.; Yepes, H.; Palacios, P.; Ruiz, M. C.; Arrais, S.; Vaca, M.; Molina, I.; Yamashina, T.

    2009-12-01

    We systematically used two approaches to analyze broadband seismic signals observed at active volcanoes: one is waveform inversion of very-long-period (VLP) signals in the frequency domain assuming possible source mechanisms; the other is a source location method of long-period (LP) and tremor using their amplitudes. The deterministic approach of the waveform inversion is useful to constrain the source mechanism and location, but is basically only applicable to VLP signals with periods longer than a few seconds. The source location method uses seismic amplitudes corrected for site amplifications and assumes isotropic radiation of S waves. This assumption of isotropic radiation is apparently inconsistent with the hypothesis of crack geometry at the LP source. Using the source location method, we estimated the best-fit source location of a VLP/LP event at Cotopaxi using a frequency band of 7-12 Hz and Q = 60. This location was close to the best-fit source location determined by waveform inversion of the VLP/LP event using a VLP band of 5-12.5 s. The waveform inversion indicated that a crack mechanism better explained the VLP signals than an isotropic mechanism. These results indicated that isotropic radiation is not inherent to the source and only appears at high frequencies. We also obtained a best-fit location of an explosion event at Tungurahua when using a frequency band of 5-10 Hz and Q = 60. This frequency band and Q value also yielded reasonable locations for the sources of tremor signals associated with lahars and pyroclastic flows at Tungurahua. The isotropic radiation assumption may be valid in a high frequency range in which the path effect caused by the scattering of seismic waves results in an isotropic radiation pattern of S waves. The source location method may be categorized as a stochastic approach based on the nature of scattering waves. We further applied the waveform inversion to VLP signals observed at only two stations during a volcanic crisis

  9. Volcanomagnetic signals associated with the quasi-continuous activity of the andesitic Merapi volcano, Indonesia: 1990-1995

    NASA Astrophysics Data System (ADS)

    Zlotnicki, J.; Bof, M.

    Merapi volcano in Java island (Indonesia) is an andesitic stratovolcano which presents long periods of effusive activity during which an endogeneous dome is continuously growing. The viscous lava dome gives rise to unstable blocks which collapse or turn into pyroclastic flows. When the volcano does not exhibit any surface activity, the overpressure within the volcano slowly increases. Depending on the quietness duration, the unrest of the volcano can start with an explosive phase during which the former dome is partly destroyed. Magnetic variations of different time constant are observed during the 1990-1995 period which includes one gas plume emission on August 26, 1990 and two eruptions on January 20, 1992 and on November 22, 1994. Compared with other types of active volcanoes, the observed volcanomagnetic variations are very small, at the most a few nanoteslas (nT). To discriminate the variations associated with the global activity from the signals correlated with each unrest phase, one has to dissociate the different time constant variations over the six-year time span. When long-term trends are removed from the magnetic field in each station of the network, an outstanding correlation between all the magnetic differences is emphasised. The midterm variations point out 2 cycles of activity which fit the stress field evolution within the edifice leading to the 1992 and 1994 eruptions. A new cycle has started in May 1995. In every identified cycle, rapid volcanomagnetic signals are well associated with stress field changes (May 1991, September 1991, February 1993, December 1993, …). Some of the volcanomagnetic variations are short-term precursory signals as the three months decrease, up to 1.3 nT, preceding the 1992 eruption. The comparison between magnetic data, seismicity and surface phenomena implies that the midterm volcanomagnetic variations associated with the cycles of Merapi activity are of piezomagnetic origin.

  10. Active mud volcanoes on the continental slope of the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Caress, D. W.; Gwiazda, R.; Melling, H.; Riedel, M.; Jin, Y. K.; Hong, J. K.; Kim, Y.-G.; Graves, D.; Sherman, A.; Lundsten, E.; Anderson, K.; Lundsten, L.; Villinger, H.; Kopf, A.; Johnson, S. B.; Hughes Clarke, J.; Blasco, S.; Conway, K.; Neelands, P.; Thomas, H.; Côté, M.

    2015-09-01

    Morphologic features, 600-1100 m across and elevated up to 30 m above the surrounding seafloor, interpreted to be mud volcanoes were investigated on the continental slope in the Beaufort Sea in the Canadian Arctic. Sediment cores, detailed mapping with an autonomous underwater vehicle, and exploration with a remotely operated vehicle show that these are young and actively forming features experiencing ongoing eruptions. Biogenic methane and low-chloride, sodium-bicarbonate-rich waters are extruded with warm sediment that accumulates to form cones and low-relief circular plateaus. The chemical and isotopic compositions of the ascending water indicate that a mixture of meteoric water, seawater, and water from clay dehydration has played a significant role in the evolution of these fluids. The venting methane supports extensive siboglinid tubeworms communities and forms some gas hydrates within the near seafloor. We believe that these are the first documented living chemosynthetic biological communities in the continental slope of the western Arctic Ocean.

  11. Volcanogenic fluorine in rainwater around active degassing volcanoes: Mt. Etna and Stromboli Island, Italy.

    PubMed

    Bellomo, S; D'Alessandro, W; Longo, M

    2003-01-01

    Many studies have assessed the strong influence of volcanic activity on the surrounding environment. This is particularly true for strong gas emitters such as Mt. Etna and Stromboli volcanoes. Among volcanic gases, fluorine compounds are potentially very harmful. Fluorine cycling through rainwater in the above volcanic areas was studied analysing more than 400 monthly bulk samples. Data indicate that only approximately 1% of fluorine emission through the plume is deposited on the two volcanic areas by meteoric precipitations. Although measured bulk rainwater fluorine fluxes are comparable to and sometimes higher than in heavily polluted areas, their influence on the surrounding vegetation is limited. Only annual crops, in fact, show some damage that could be an effect of fluorine deposition, indicating that long-living endemic plant species or varieties have developed some kind of resistance.

  12. Attaining high-resolution eruptive histories for active arc volcanoes with argon geochronology

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.

    2012-04-01

    Geochronology of active arc volcanoes commonly illuminates eruptive behavior over tens to hundreds of thousands of years, lengthy periods of repose punctuated by short eruptive episodes, and spatial and compositional changes with time. Despite the >1 Gyr half-life of 40K, argon geochronology is an exceptional tool for characterizing Pleistocene to Holocene eruptive histories and for placing constraints on models of eruptive behavior. Reliable 40Ar/39Ar ages of calc-alkaline arc rocks with rigorously derived errors small enough (± 500 to 3,000 years) to constrain eruptive histories are attainable using careful procedures. Sample selection and analytical work in concert with geologic mapping and stratigraphic studies are essential for determining reliable eruptive histories. Preparation, irradiation and spectrometric techniques have all been optimized to produce reliable, high-precision results. Examples of Cascade and Alaska/Aleutian eruptive histories illustrating duration of activity from single centers, eruptive episodicity, and spatial and compositional changes with time will be presented: (1) Mt. Shasta, the largest Cascade stratovolcano, has a 700,000-year history (Calvert and Christiansen, 2011 Fall AGU). A similar sized and composition volcano (Rainbow Mountain) on the Cascade axis was active 1200-950 ka. The eruptive center then jumped west 15 km to the south flank of the present Mt. Shasta and produced a stratovolcano from 700-450 ka likely rivaling today's Mt. Shasta. The NW portion of that edifice failed in an enormous (>30 km3) debris avalanche. Vents near today's active summit erupted 300-135 ka, then 60-15 ka. A voluminous, but short-lived eruptive sequence occurred at 11 ka, including a summit explosion producing a subplinian plume, followed by >60 km3 andesite-dacite Shastina domes and flows, then by the flank dacite Black Butte dome. Holocene domes and flows subsequently rebuilt the summit and flowed to the north and east. (2) Mt. Veniaminof on

  13. Developments in analysis of basaltic ash applied to recent activity at Etna and Stromboli volcanoes

    NASA Astrophysics Data System (ADS)

    Lautze, N. C.; Taddeucci, J.; Andronico, D.; Tornetta, L.; Cannata, C.; Houghton, B. F.; Cristaldi, A.

    2009-12-01

    Advances in analytical techniques coupled with recent high levels of activity at Etna and Stromboli have offered a unique opportunity to sample and analyze of basaltic ash particles. We have performed new micro-scale analysis of basaltic ash from a variety of eruptive conditions: a weak ash-producing event at Etna on 11 November 2006, ash emission, paroxysmal explosions and lava-sea water interaction during the 2007 eruptive crisis of Stromboli volcano, and finally more typical Strombolian activity in 2008 at Stromboli. Etna samples were collected at eight locations between 2 and 20 km from source. Stromboli samples were collected between 28 February and 19 March 2007, and from single explosions in September 2008. A JEOL JSM 6500 Field Emission Scanning Electron Microprobe (FE-SEM) was used to image and quantify millimeter- to submicron-scale features of ash particles. Beside qualitative observation of the particles, semi-automated FE-SEM data include particle morphoscopy (area, perimeter, compactness, equivalent diameter) and surface chemistry. The morphoscopy data can be compared to grain size data collected by conventional techniques, while the surface chemistry data can be considered a proxy for component analysis, more typically performed using a binocular microscope, as it reflects the degree of crystallinity and alteration of the particles. Preliminary data indicate that insight into the particle source and eruptive dynamics of both volcanoes can be obtained from detailed analysis of the ash. In particular, the different sources of ash at Stromboli have highly distinctive alteration signatures, while the Etna samples exemplify the potential of the approach to discern subtle differences in ash particles from the same plume collected at different locations, thus outlining relatively small-scale plume zonations.

  14. How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

    NASA Astrophysics Data System (ADS)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Bagnardi, Marco; Acocella, Valerio

    2016-04-01

    Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we use numerical models to show that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Galápagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observation. We then develop a general model for the stress state at volcanic edifices with calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control the shallow accumulation of magma in stacked sills, consistently with observations as well as the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

  15. Seismicity and eruptive activity at Fuego Volcano, Guatemala: February 1975 -January 1977

    USGS Publications Warehouse

    Yuan, A.T.E.; McNutt, S.R.; Harlow, D.H.

    1984-01-01

    We examine seismic and eruptive activity at Fuego Volcano (14??29???N, 90?? 53???W), a 3800-m-high stratovolcano located in the active volcanic arc of Guatemala. Eruptions at Fuego are typically short-lived vulcanian eruptions producing ash falls and ash flows of high-alumina basalt. From February 1975 to December 1976, five weak ash eruptions occurred, accompanied by small earthquake swarms. Between 0 and 140 (average ??? 10) A-type or high-frequency seismic events per day with M > 0.5 were recorded during this period. Estimated thermal energies for each eruption are greater by a factor of 106 than cumulative seismic energies, a larger ratio than that reported for other volcanoes. Over 4000 A-type events were recorded January 3-7, 1977 (cumulative seismic energy ??? 109 joules), yet no eruption occurred. Five 2-hour-long pulses of intense seismicity separated by 6-hour intervals of quiescence accounted for the majority of events. Maximum likelihood estimates of b-values range from 0.7 ?? 0.2 to 2.1 ?? 0.4 with systematically lower values corresponding to the five intense pulses. The low values suggest higher stress conditions. During the 1977 swarm, a tiltmeter located 6 km southeast of Fuego recorded a 14 ?? 3 microradian tilt event (down to SW). This value is too large to represent a simple change in the elastic strain field due to the earthquake swarm. We speculate that the earthquake swarm and tilt are indicative of subsurface magma movement. ?? 1984.

  16. Volcano infrasound: A review

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey Bruce; Ripepe, Maurizio

    2011-09-01

    Exploding volcanoes, which produce intense infrasound, are reminiscent of the veritable explosion of volcano infrasound papers published during the last decade. Volcano infrasound is effective for tracking and quantifying eruptive phenomena because it corresponds to activity occurring near and around the volcanic vent, as opposed to seismic signals, which are generated by both surface and internal volcanic processes. As with seismology, infrasound can be recorded remotely, during inclement weather, or in the dark to provide a continuous record of a volcano's unrest. Moreover, it can also be exploited at regional or global distances, where seismic monitoring has limited efficacy. This paper provides a literature overview of the current state of the field and summarizes applications of infrasound as a tool for better understanding volcanic activity. Many infrasound studies have focused on integration with other geophysical data, including seismic, thermal, electromagnetic radiation, and gas spectroscopy and they have generally improved our understanding of eruption dynamics. Other work has incorporated infrasound into volcano surveillance to enhance capabilities for monitoring hazardous volcanoes and reducing risk. This paper aims to provide an overview of volcano airwave studies (from analog microbarometer to modern pressure transducer) and summarizes how infrasound is currently used to infer eruption dynamics. It also outlines the relative merits of local and regional infrasound surveillance, highlights differences between array and network sensor topologies, and concludes with mention of sensor technologies appropriate for volcano infrasound study.

  17. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

    article title:  Eyjafjallajökull, Iceland, Volcano Ash Cloud     View larger ... Europe and captured this image of the Eyjafjallajökull Volcano ash cloud as it continued to drift over the continent. Unlike other ...

  18. Submarine laser communications

    NASA Astrophysics Data System (ADS)

    McConathy, D. R.

    The Department of the Navy and the Defense Advanced Research Projects Agency (DARPA) are sponsoring a joint study to investigate the use of blue-green laser technology to comunicate with submarines at operating depths. Two approaches are under investigation - one in which the laser itself is space-based, and the other in which the laser is ground-based with its beam redirected to the earth's surface by an orbiting mirror. This paper discusses these two approaches, and presents a brief history of activities which led to the current studies.

  19. International Volcanological Field School in Kamchatka and Alaska: Experiencing Language, Culture, Environment, and Active Volcanoes

    NASA Astrophysics Data System (ADS)

    Eichelberger, J. C.; Gordeev, E.; Ivanov, B.; Izbekov, P.; Kasahara, M.; Melnikov, D.; Selyangin, O.; Vesna, Y.

    2003-12-01

    The Kamchatka State University of Education, University of Alaska Fairbanks, and Hokkaido University are developing an international field school focused on explosive volcanism of the North Pacific. An experimental first session was held on Mutnovsky and Gorely Volcanoes in Kamchatka during August 2003. Objectives of the school are to:(1) Acquaint students with the chemical and physical processes of explosive volcanism, through first-hand experience with some of the most spectacular volcanic features on Earth; (2) Expose students to different concepts and approaches to volcanology; (3) Expand students' ability to function in a harsh environment and to bridge barriers in language and culture; (4) Build long-lasting collaborations in research among students and in teaching and research among faculty in the North Pacific region. Both undergraduate and graduate students from Russia, the United States, and Japan participated. The school was based at a mountain hut situated between Gorely and Mutnovsky Volcanoes and accessible by all-terrain truck. Day trips were conducted to summit craters of both volcanoes, flank lava flows, fumarole fields, ignimbrite exposures, and a geothermal area and power plant. During the evenings and on days of bad weather, the school faculty conducted lectures on various topics of volcanology in either Russian or English, with translation. Although subjects were taught at the undergraduate level, lectures led to further discussion with more advanced students. Graduate students participated by describing their research activities to the undergraduates. A final session at a geophysical field station permitted demonstration of instrumentation and presentations requiring sophisticated graphics in more comfortable surroundings. Plans are underway to make this school an annual offering for academic credit in the Valley of Ten Thousand Smokes, Alaska and in Kamchatka. The course will be targeted at undergraduates with a strong interest in and

  20. A forward modeling approach to relate geophysical observables at active volcanoes to deep magma dynamics

    NASA Astrophysics Data System (ADS)

    Montagna, C. P.; Longo, A.; Papale, P.; Vassalli, M.; Saccorotti, G.; Cassioli, A.

    2010-12-01

    Geophysical signals usually recorded at active volcanoes mainly consist of i) seismicity - high frequency volcano-tectonic events, volcanic tremor, and LP, VLP, and ULP events, ii) ground displacement, and iii) gravity changes. These signals are inverted to constrain the characteristics of the underground signal source, usually under the simplifying assumptions of point source or small volume homogeneous source with simple geometry. We have instead designed a forward approach, that complements the more classical inverse approaches, whereby magma chamber dynamics are numerically solved for compressible-to-incompressible multi-component magmas in geometrically complex systems constituted by one or more magma chambers connected through dykes. Our new code, that we named GALES (GAlerkin LEast Squares), solves the complex time-space-dependent dynamics of convection and mixing of magmas with different composition and properties, and reveals patterns of overpressure much more complex than commonly assumed in inverse analyses. Time-space-dependent stress distributions computed along the rigid magma-wall boundaries are employed as boundary conditions in either numerical simulations of wave propagation through the rock system by taking into account wall rock heterogeneities and topographic surface, or semi-analytical solutions of the Green’s functions in homogeneous infinite space. Ground displacement computed at the topographic surface ranges from the seismic to the quasi-static frequency band. Density variations associated to the simulated magma convection dynamics are instead employed to determine the corresponding gravity change at the surface. Seismicity, ground deformation, and gravity changes associated to deep magma dynamics are therefore computed as a function of time at different points on the Earth’s surface. Performed numerical simulations involve cases with largely different magma/dyke size, geometry and depth, and magma compositions from basaltic to

  1. The diversity of mud volcanoes in the landscape of Azerbaijan

    NASA Astrophysics Data System (ADS)

    Rashidov, Tofig

    2014-05-01

    on surface, often of plane-conical shape, rising for 5 to 400 m and more over the country (for example, mud volcano Toragay, 400 m height). The base diameter is from 100 m to 3-4 km and more. Like the magmatic ones, the mud volcanoes are crowned with crater of convex-plane or deeply-seated shape. In Azerbaijan there are all types of mud volcanoes: active, extinct, buried, submarine, island, abundantly oil seeping. According to their morphology they are defined into cone-shaped, dome-shaped, ridge-shaped, plateau-shaped. The crater shapes are also various: conical, convex-plane, shield-shaped, deeply-seated, caldera-like. The most complete morphological classification was given in "Atlas of mud volcanoes of Azerbaijan" (Yakubov et al., 1971). Recently (Aliyev Ad. et al., 2003) it was proposed a quite new morphological classification of mud volcanoes of Azerbaijan. For the first time the mud volcanic manifestations had been defined. Volcanoes are ranged according to morphological signs, crater shape and type of activity.

  2. Nicaraguan Volcanoes

    Atmospheric Science Data Center

    2013-04-18

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

  3. Linking observations at active volcanoes to physical processes through conduit flow modelling

    NASA Astrophysics Data System (ADS)

    Thomas, Mark; Neuberg, Jurgen

    2010-05-01

    Low frequency seismic events observed on volcanoes such as Soufriere hills, Montserrat may offer key indications about the state of a volcanic system. To obtain a better understanding of the source of these events and of the physical processes that take place within a volcano it is necessary to understand the conditions of magma a depth. This can be achieved through conduit flow modelling (Collier & Neuberg, 2006). 2-D compressible Navier-Stokes equations are solved through a Finite Element approach, for differing initial water and crystal contents, magma temperatures, chamber overpressures and geometric shapes of conduit. In the fully interdependent modelled system each of these variables has an effect on the magma density, viscosity, gas content, and also the pressure within the flow. These variables in turn affect the magma ascent velocity and the overall eruption dynamics of an active system. Of particular interest are the changes engendered in the flow by relativity small variations in the conduit geometry. These changes can have a profound local effect of the ascent velocity of the magma. By restricting the width of 15m wide, 5000m long vertical conduit over a 100m distance a significant acceleration of the magma is seen in this area. This has implications for the generation of Low-Frequency (LF) events at volcanic systems. The strain-induced fracture of viscoelastic magma or brittle failure of melt has been previously discussed as a possible source of LF events by several authors (e.g. Tuffen et al., 2003; Neuberg et al., 2006). The location of such brittle failure however has been seen to occur at relativity shallow depths (<1000m), which does not agree with the location of recorded LF events. By varying the geometry of the conduit and causing accelerations in the magma flow, localised increases in the shear strain rate of up to 30% are observed. This provides a mechanism of increasing the depth over witch brittle failure of melt may occur. A key observable

  4. Organic geochemical signatures controlling methane outgassing at active mud volcanoes in the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    DongHun, Lee; YoungKeun, Jin; JungHyun, Kim; Heldge, Niemann; JongKu, Gal; BoHyung, Choi

    2016-04-01

    Based on the water column acoustic anomalies related to active methane (CH4) venting, numerous active Mud Volcanoes (MVs) were recently identified at ~282, ~420, and ~740 m water depths on the continental slope of the Canadian Beaufort Sea (Paull et al., 2015). While geophysical aspects such as the multibeam bathymetric mapping are thoroughly investigated, biogeochemical processes controlling outgassing CH4 at the active MVs are not well constrained. Here, we investigated three sediment cores from the active MVs and one sediment core from a non-methane influenced reference site recovered during the ARA-05C expedition with the R/V ARAON in 2014. We analyzed lipid biomarkers and their stable carbon isotopic values (δ13C) in order to determine key biogeochemical processes involved in CH4 cycling in the MV sediments. Downcore CH4 and sulphate (SO42-) concentration measurements revealed a distinct sulfate-methane transition zone (SMTZ) at the shallow sections of the cores (15 - 45 cm below seafloor (cm bsf) at 282 m MV, 420 m MV, and 740 m MV). The most abundant diagnostic lipid biomarkers in the SMTZ were sn-2-hydroxyarchaeol (-94‰) and archaeol (-66‰) with the sn-2-hydroxyarchaeol: archaeol ratio of 1.1 to 5, indicating the presence of ANME-2 or -3. However, we also found substantial amounts of monocyclic biphytane-1 (BP-1, -118‰), which is rather indicative for ANME-1. Nevertheless, the concentration of sn-2-hydroxyarchaeol was 2-fold higher than any other archaeal lipids, suggesting a predominant ANME-2 or -3 rather than ANME-1 as a driving force for the anaerobic methane oxidation (AOM) in these systems. We will further investigate the microbial community at the active MVs using nucleic acid (RNA and DNA) sequence analyses in near future. Our study provides first biogeochemical data set of the active MVs in the Canadian Beaufort Sea, which helps to better understand CH4 cycling mediated in these systems. Reference Paull, C.K., et al. (2015), Active mud

  5. Increasing sediment accumulation rates in La Fonera (Palamós) submarine canyon axis and their relationship with bottom trawling activities

    NASA Astrophysics Data System (ADS)

    Puig, P.; Martín, J.; Masqué, P.; Palanques, A.

    2015-10-01

    Previous studies conducted in La Fonera (Palamós) submarine canyon (NW Mediterranean) found that trawling activities along the canyon flanks cause resuspension and transport of sediments toward the canyon axis. 210Pb chronology supported by 137Cs dating applied to a sediment core collected at 1750 m in 2002 suggested a doubling of the sediment accumulation rate since the 1970s, coincident with the rapid industrialization of the local trawling fleet. The same canyon area has been revisited a decade later, and new data are consistent with a sedimentary regime shift during the 1970s and also suggest that the accumulation rate during the last decade could be greater than expected, approaching ~2.4 cm yr-1 (compared to ~0.25 cm yr-1 pre-1970s). These results support the hypothesis that commercial bottom trawling can substantially affect sediment dynamics and budgets on continental margins, eventually initiating the formation of anthropogenic depocenters in submarine canyon environments.

  6. Active tectonic structures and submarine landslides offshore southern Apulia (Italy): a new scenario for the 1743 earthquake and subsequent tsunami

    NASA Astrophysics Data System (ADS)

    Milia, Alfonsa; Iannace, Pietro; Torrente, Maurizio M.

    2017-01-01

    The southern Apulia foreland recorded a strong (Imax=X MCS) earthquake in 1743 and a concomitant tsunami, which struck the southeastern Salento coast. The seismo-genetic fault and the triggering factors of the tsunami are unknown. Three-dimensional interpretation of multichannel seismic profiles calibrated by wells using a GIS software enabled the recognition of the stratigraphic succession, structural framework, and submarine landslides offshore Salento. A thin Pliocene unit overlying the Mesozoic-Cenozoic substrate is covered by a Pleistocene succession separated by a Middle Pleistocene unconformity that formed during the regional uplift of Salento. The latter gave rise to the morphologic conditions for the deposition of a prograding wedge off the Salento coast, with a shelf break located at 150 m depth. Normal faults, mainly oriented NW-SE, displaced the early Lower Pleistocene succession and are buried by younger deposits. Since the Middle Pleistocene, a compressional event gave rise to the Apulia uplift and large folds and basement-involved reverse faults that are active in the eastern part of Apulia. A huge (58 km3) slump affecting the Middle Pleistocene prograding wedge has been documented offshore the southeast coast of Salento. The proposed geological scenario of the 1743 earthquake and subsequent tsunami is (1) an initial strong earthquake (Imax=X MCS) associated with a thrust fault located in the eastern sector of the Apulia offshore, (2) a shacking-induced large-volume slump offshore Otranto, and (3) landslide-triggered tsunamis that struck the Salento coast.

  7. Submarine evidence for large-scale debris avalanches in the Lesser Antilles Arc

    NASA Astrophysics Data System (ADS)

    Deplus, Christine; Le Friant, Anne; Boudon, Georges; Komorowski, Jean-Christophe; Villemant, Benoit; Harford, Chloe; Ségoufin, Jacques; Cheminée, Jean-Louis

    2001-10-01

    Results from a recent marine geophysical survey demonstrate the importance of the process of flank collapse in the growth and evolution of volcanoes along an island arc. The Aguadomar cruise, aboard the French R/V L'Atalante, surveyed the flanks of the Lesser Antilles Arc between the islands of Montserrat and St. Lucia. Analysis of the data shows that flank collapse events occurred on active volcanoes all along the arc and resulted in debris avalanches, some of them being of large magnitude. The debris avalanche deposits display hummocky topography on the swath bathymetry, speckled pattern on backscatter images, hyperbolic facies on 3.5 kHz echosounder data and chaotic units on air gun seismic profiles. They extend from horseshoe-shaped structures previously identified on the subaerial part of the volcanoes. In the southern part of the arc, large-scale debris avalanche deposits were identified on the floor of the Grenada Basin west of active volcanoes on Dominica, Martinique and St. Lucia. The extent of debris avalanche deposits off Dominica is about 3500 km 2. The debris avalanches have resulted from major flank collapse events which may be mainly controlled by the large-scale structure of the island arc and the presence of the deep Grenada Basin. In the northern part of the arc, several debris avalanche deposits were also identified around the island of Montserrat. With smaller extent (20-120 km 2), they are present on the east, south and west submarine flanks of Soufriere Hills volcano which has been erupting since July 1995. Flank collapse is thus a recurrent process in the recent history of this volcano. The marine data are also relevant for a discussion of the transport mechanisms of debris avalanches on the seafloor surrounding a volcanic island arc.

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

    NASA Astrophysics Data System (ADS)

    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

  9. Volcano hazards at Newberry Volcano, Oregon

    USGS Publications Warehouse

    Sherrod, David R.; Mastin, Larry G.; Scott, William E.; Schilling, Steven P.

    1997-01-01

    Newberry volcano is a broad shield volcano located in central Oregon. It has been built by thousands of eruptions, beginning about 600,000 years ago. At least 25 vents on the flanks and summit have been active during several eruptive episodes of 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. The most-visited part of the volcano is Newberry Crater, a volcanic depression or caldera at the summit of the volcano. Seven campgrounds, two resorts, six summer homes, and two major lakes (East and Paulina Lakes) are nestled in the caldera. The caldera has been the focus of Newberry's volcanic activity for at least the past 10,000 years. Other eruptions during this time have occurred along a rift zone on the volcano's northwest flank and, to a lesser extent, the south flank. Many striking volcanic features lie in Newberry National Volcanic Monument, which is managed by the U.S. Forest Service. The monument includes the caldera and extends along the northwest rift zone to the Deschutes River. About 30 percent of the area within the monument is covered by volcanic products erupted during the past 10,000 years from Newberry volcano. Newberry volcano is presently 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. This report 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. In terms of our own lifetimes, volcanic events at Newberry are not of day-to-day concern because they occur so infrequently; however, the consequences of some types of eruptions can be severe. When Newberry

  10. The heartbeat of the volcano: The discovery of episodic activity at Prometheus on Io

    USGS Publications Warehouse

    Davies, A.G.; Wilson, L.; Matson, D.; Leone, G.; Keszthelyi, L.; Jaeger, W.

    2006-01-01

    The temporal signature of thermal emission from a volcano is a valuable clue to the processes taking place both at and beneath the surface. The Galileo Near Infrared Mapping Spectrometer (NIMS) observed the volcano Prometheus, on the jovian moon Io, on multiple occasions between 1996 and 2002. The 5 micron (??m) brightness of this volcano shows considerable variation from orbit to orbit. Prometheus exhibits increases in thermal emission that indicate episodic (though non-periodic) effusive activity in a manner akin to the current Pu'u 'O'o-Kupaianaha (afterwards referred to as the Pu'u 'O'o) eruption of Kilauea, Hawai'i. The volume of material erupted during one Prometheus eruption episode (defined as the interval from minimum thermal emission to peak and back to minimum) from 6 November 1996 to 7 May 1997 is estimated to be ???0.8 km3, with a peak instantaneous volumetric flux (effusion rate) of ???140 m3 s-1, and an averaged volumetric flux (eruption rate) of ???49 m3 s-1. These quantities are used to model subsurface structure, magma storage and magma supply mechanisms, and likely magma chamber depth. Prometheus appears to be supplied by magma from a relatively shallow magma chamber, with a roof at a minimum depth of ???2-3 km and a maximum depth of ???14 km. This is a much shallower depth range than sources of supply proposed for explosive, possibly ultramafic, eruptions at Pillan and Tvashtar. As Prometheus-type effusive activity is widespread on Io, shallow magma chambers containing magma of basaltic or near-basaltic composition and density may be common. This analysis strengthens the analogy between Prometheus and Pu'u 'O'o, at least in terms of eruption style. Even though the style of eruption appears to be similar (effusive emplacement of thin, insulated, compound pahoehoe flows) the scale of activity at Prometheus greatly exceeds current activity at Pu'u 'O'o in terms of volume erupted, area covered, and magma flux. Whereas the estimated magma chamber at

  11. Seismic body wave separation in volcano-tectonic activity inferred by the Convolutive Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Capuano, Paolo; De Lauro, Enza; De Martino, Salvatore; Falanga, Mariarosaria; Petrosino, Simona

    2015-04-01

    One of the main challenge in volcano-seismological literature is to locate and characterize the source of volcano/tectonic seismic activity. This passes through the identification at least of the onset of the main phases, i.e. the body waves. Many efforts have been made to solve the problem of a clear separation of P and S phases both from a theoretical point of view and developing numerical algorithms suitable for specific cases (see, e.g., Küperkoch et al., 2012). Recently, a robust automatic procedure has been implemented for extracting the prominent seismic waveforms from continuously recorded signals and thus allowing for picking the main phases. The intuitive notion of maximum non-gaussianity is achieved adopting techniques which involve higher-order statistics in frequency domain., i.e, the Convolutive Independent Component Analysis (CICA). This technique is successful in the case of the blind source separation of convolutive mixtures. In seismological framework, indeed, seismic signals are thought as the convolution of a source function with path, site and the instrument response. In addition, time-delayed versions of the same source exist, due to multipath propagation typically caused by reverberations from some obstacle. In this work, we focus on the Volcano Tectonic (VT) activity at Campi Flegrei Caldera (Italy) during the 2006 ground uplift (Ciaramella et al., 2011). The activity was characterized approximately by 300 low-magnitude VT earthquakes (Md < 2; for the definition of duration magnitude, see Petrosino et al. 2008). Most of them were concentrated in distinct seismic sequences with hypocenters mainly clustered beneath the Solfatara-Accademia area, at depths ranging between 1 and 4 km b.s.l.. The obtained results show the clear separation of P and S phases: the technique not only allows the identification of the S-P time delay giving the timing of both phases but also provides the independent waveforms of the P and S phases. This is an enormous

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  13. Obstacle avoidance sonar for submarines

    NASA Astrophysics Data System (ADS)

    Dugas, Albert C.; Webman, Kenneth M.

    2002-05-01

    The Advanced Mine Detection Sonar (AMDS) system was designed to operate in poor environments with high biological and/or shallow-water boundary conditions. It provides increased capability for active detection of volume, close-tethered, and bottom mines, as well as submarine and surface target active/passive detection for ASW and collision avoidance. It also provides bottom topography mapping capability for precise submarine navigation in uncharted littoral waters. It accomplishes this by using advanced processing techniques with extremely narrow beamwidths. The receive array consists of 36 modules arranged in a 15-ft-diameter semicircle at the bottom of the submarine sonar dome to form a chin-mounted array. Each module consists of 40 piezoelectric rubber elements. The modules provide the necessary signal conditioning to the element data prior to signal transmission (uplink) through the hull. The elements are amplified, filtered, converted to digital signals by an A/D converter, and multiplexed prior to uplink to the inboard receiver. Each module also has a downlink over which it receives synchronization and mode/gain control. Uplink and downlink transmission is done using fiberoptic telemetry. AMDS was installed on the USS Asheville. The high-frequency chin array for Virginia class submarines is based on the Asheville design.

  14. Subsurface mass migration at active volcanoes: what we learnt from the VOLUME project

    NASA Astrophysics Data System (ADS)

    Saccorotti, G.; Volume Team

    2009-04-01

    Movements of multiphase fluids beneath active volcanoes are generally detected at the surface in terms of changes in geophysical and geochemical observables. The prompt detection and interpretation of such signals thus represent a crucial step toward the short-term evaluation of volcanic hazard. Funded through the European 6th framework program, the VOLUME project joined 19 institutions from 6 EU and 5 extra-european countries under the common goal of improving our understanding of how subsurface mass movement manifests itself at the surface, in turn revealing the significance of such movements as precursors to impending eruptions. We integrated high-end experimental procedures with a robust modeling framework to address some of the most relevant issues of modern, quantitative volcanology. In particular, our studies focused on: (i) Unrevealing the complex interplay between hydrothermal and magmatic fluids in generating the observed geophysical / geochemical signals, (ii) Detailing the location, geometry and dynamics of magma pathways and storage zones (iii) Probing variations of the elastic parameters of volcanic media in response to stress changes induced by mass migration, and (iv) Developing a robust computational framework for forward-modelling the geophysical observables resulting from the dynamics of multiphase magmatic systems. VOLUME activities developed at both european and extra-european volcanoes. We present here the most striking results obtained at two italian test-sites, namely Etna and Campi Flegrei, for which we had available data sets of unprecedented sensitivity and temporal resolution. Results from Etna include a) mapping of the shallow plumbing system from Moment-Tensor inversion of broadband seismic signal, b) the detection of deep magma intrusion from inversion of joint gravity-tremor anomalies; c) the measurement of changes in both elastic anisotropy and seismic velocity concomitant to the waning stage of the 2002 NE flank lava effusion; and

  15. Active high-resolution seismic tomography of compressional wave velocity and attenuation structure at Medicine Lake Volcano, Northern California Cascade Range

    NASA Astrophysics Data System (ADS)

    Evans, John R.; Zucca, John J.

    1988-12-01

    We determine compressional wave velocity and attenuation structures for the upper crust beneath Medicine Lake volcano in northeast California using a high-resolution active source seismic tomography method. Medicine Lake volcano is a basalt through rhyolite shield volcano of the Cascade Range, lying east of the range axis. The Pg wave from eight explosive sources which has traveled upward through the target volume to a dense array of 140 seismographs provides 1- to 2-km resolution in the upper 5 to 7 km of the crust beneath the volcano. The experiment tests the hypothesis that Cascade Range volcanoes of this type are underlain only by small silicic magma chambers. We image a low-velocity low-Q region not larger than a few tens of cubic kilometers in volume beneath the summit caldera, supporting the hypothesis. A shallower high-velocity high-density feature, previously known to be present, is imaged for the first time in full plan view; it is east-west elongate, paralleling a topographic lineament between Medicine Lake volcano and Mount Shasta. This lineament is interpreted to be the result of an old crustal weakness now affecting the emplacement of magma, both on direct ascent from the lower crust and mantle and in migration from the shallow silicic chamber to summit vents. Differences between this high-velocity feature and the equivalent feature at Newbeny volcano, a volcano in central Oregon resembling Medicine Lake volcano, may partly explain the scarcity of surface hydrothermal features at Medicine Lake volcano. A major low-velocity low-Q feature beneath the southeast flank of the volcano, in an area with no Holocene vents, is interpreted as tephra, flows, and sediments from the volcano deeply ponded on the downthrown side of the Gillem fault, a normal fault mapped at the surface north of the volcano. A high-Q normal-velocity feature beneath the north rim of the summit caldera may be a small, possibly hot, subsolidus intrusion. A high-velocity low-Q region

  16. Nyiragonga Volcano

    NASA Technical Reports Server (NTRS)

    2001-01-01

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

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

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

  17. Contribution of space platforms to a ground and airborne remote-sensing programme over active Italian volcanoes

    NASA Technical Reports Server (NTRS)

    Cassinis, R.; Lechi, G. M.; Tonelli, A. M.

    1974-01-01

    ERTS-1 imagery of the volcanic areas of southern Italy was used primarily for the evaluation of space platform capabilties in the domains of regional geology, soil and rock-type classification and, more generally, to study the environment of active volcanoes. The test sites were selected and equipped primarily to monitor thermal emission, but ground truth data was also collected in other domains (reflectance of rocks, soils and vegetation). The test areas were overflown with a two channel thermal scanner, while a thermo camera was used on the ground to monitor the hot spots. The primary goal of this survey was to plot the changes in thermal emission with time in the framework of a research program for the surveillance of active volcanoes. However, another task was an evaluation of emissivity changes by comparing the outputs of the two thermal channels. These results were compared with the reflectance changes observed on multispectral ERTS-1 imagery.

  18. Reunion Island Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  19. The proximal part of the giant submarine Wailau landslide, Molokai, Hawaii

    USGS Publications Warehouse

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

    2002-01-01

    The main break-in-slope on the northern submarine flank of Molokai at -1500 to -1250 m is a shoreline feature that has been only modestly modified by the Wailau landslide. Submarine canyons above the break-in-slope, including one meandering stream, were subaerially carved. Where such canyons cross the break-in-slope, plunge pools may form by erosion from bedload sediment carried down the canyons. West Molokai Volcano continued infrequent volcanic activity that formed a series of small coastal sea cliffs, now submerged, as the island subsided. Lavas exposed at the break-in-slope are subaerially erupted and emplaced tholeiitic shield lavas. Submarine rejuvenated-stage volcanic cones formed after the landslide took place and following at least 400-500 m of subsidence after the main break-in-slope had formed. The sea cliff on east Molokai is not the headwall of the landslide, nor did it form entirely by erosion. It may mark the location of a listric fault similar to the Hilina faults on present-day Kilauea Volcano. The Wailau landslide occurred about 1.5 Ma and the Kalaupapa Peninsula most likely formed 330??5 ka. Molokai is presently stable relative to sea level and has subsided no more than 30 m in the last 330 ka. At their peak, West and East Molokai stood 1.6 and 3 km above sea level. High rainfall causes high surface runoff and formation of canyons, and increases groundwater pressure that during dike intrusions may lead to flank failure. Active shield or postshield volcanism (with dikes injected along rift zones) and high rainfall appear to be two components needed to trigger the deep-seated giant Hawaiian landslides. ?? 2002 Elsevier Science B.V. All rights reserved.

  20. Strombolian surface activity regimes at Yasur volcano, Vanuatu, as observed by Doppler radar, infrared camera and infrasound

    NASA Astrophysics Data System (ADS)

    Meier, K.; Hort, M.; Wassermann, J.; Garaebiti, E.

    2016-08-01

    In late 2008 we recorded a continuous multi-parameter data set including Doppler radar, infrared and infrasound data at Yasur volcano, Vanuatu. Our recordings cover a transition in explosive style from ash-rich to ash-free explosions followed again by a phase of high ash discharge. To assess the present paradigm of Strombolian behavior in this study we investigate the geophysical signature of these different explosive episodes and compare our results to observations at Stromboli volcano, Italy. To this end we characterize Yasur's surface activity in terms of material movement, temperature and excess pressure. The joint temporal trend in these data reveals smooth variations of surface activity and regime-like persistence of individual explosion forms over days. Analysis of all data types shows ash-free and ash-rich explosive styles similar to those found at Stromboli volcano. During ash-free activity low echo powers, high explosion velocities and high temperatures result from the movement of isolated hot ballistic clasts. In contrast, ash-rich episodes exhibit high echo powers, low explosion velocities and low temperatures linked to the presence of colder ash-rich plumes. Furthermore ash-free explosions cause high excess pressure signals exhibiting high frequencies opposed to low-amplitude, low-frequency signals accompanying ash-rich activity. To corroborate these findings we compare fifteen representative explosions of each explosive episode. Explosion onset velocities derived from Doppler radar and infrared camera data are in excellent agreement and consistent with overall observations in each regime. Examination of infrasound recordings likewise confirms our observations, although a weak coupling between explosion velocity and excess pressure indicates changes in wave propagation. The overall trend in explosion velocity and excess pressure however demonstrates a general correlation between explosive style and explosion intensity, and points to stability of the

  1. Characterising Seismicity at Alutu, an Actively Deforming Volcano in the Main Ethiopian Rift

    NASA Astrophysics Data System (ADS)

    Wilks, M.; Nowacki, A.; Kendall, J. M.; Wookey, J. M.; Biggs, J.; Bastow, I. D.; Ayele, A.; Bedada, T.

    2013-12-01

    The Main Ethiopian Rift (MER) provides a unique example of the tectonic and volcanic processes occuring during the transition from continental rifting to oceanic spreading. Situated 100 km south of Addis Ababa along the eastern rift margin, Alutu is a silicic stratovolcano that geodetic measurements (InSAR and GPS) have shown is actively deforming. Though the volcano has received relatively little scientific attention it is also a site of economic significance as a geothermal power plant resides within the caldera. As part of ARGOS (Alutu Research Geophysical ObservationS), a multi-disciplinary project aiming to investigate the magmatic and hydrothermal processes occuring at Alutu, a seismic network of 12 broadband seismometers was deployed in January 2012. Other components of ARGOS include InSAR, GPS, geologic mapping and magnetotellurics. From the seismic dataset, P- and S-wave arrivals across the array were manually picked and used to locate events using a non-linear earthquake location algorithm (NonLinLoc) and a predefined 1D velocity model. Perturbations were later applied to this velocity model to investigate the sensitivity of the locations and evaluate the true uncertainties of the solutions. Over 1000 events were successfully located during 2012, where picks were possible at 4 or more stations. Seismicity clusters at both shallow depths (z<2 km) beneath the caldera and at deeper depths of 5-15 km. There is a significant increase in seismicity during the rainy months, suggesting the shallow events may be related to the hydrothermal system. We interpret the deeper events as being magmatic in origin. Events are also located along the eastern border faults that bound the outer edges of the MER and highlights that seismicity arises concurrently via tectonic processes. An adapted version of Richter's original local magnitude scale (ML) to account for attenuation within the MER (Keir et al., 2006) was then used to compute magnitudes for the best located events

  2. Dynamics and kinematics of eruptive activity at Fuego volcano, Guatemala 2005--2009

    NASA Astrophysics Data System (ADS)

    Lyons, John J.

    Volcanoes are the surficial expressions of complex pathways that vent magma and gasses generated deep in the Earth. Geophysical data record at least the partial history of magma and gas movement in the conduit and venting to the atmosphere. This work focuses on developing a more comprehensive understanding of explosive degassing at Fuego volcano, Guatemala through observations and analysis of geophysical data collected in 2005--2009. A pattern of eruptive activity was observed during 2005--2007 and quantified with seismic and infrasound, satellite thermal and gas measurements, and lava flow lengths. Eruptive styles are related to variable magma flux and accumulation of gas. Explosive degassing was recorded on broadband seismic and infrasound sensors in 2008 and 2009. Explosion energy partitioning between the ground and the atmosphere shows an increase in acoustic energy from 2008 to 2009, indicating a shift toward increased gas pressure in the conduit. Very-long-period (VLP) seismic signals are associated with the strongest explosions recorded in 2009 and waveform modeling in the 10--30 s band produces a best-fit source location 300 m west and 300 m below the summit crater. The calculated moment tensor indicates a volumetric source, which is modeled as a dike feeding a SW-dipping (35°) sill. The sill is the dominant component and its projection to the surface nearly intersects the summit crater. The deformation history of the sill is interpreted as: (1) an initial inflation due to pressurization, followed by (2) a rapid deflation as overpressure is explosively release, and finally (3) a reinflation as fresh magma flows into the sill and degasses. Tilt signals are derived from the horizontal components of the seismometer and show repetitive inflation-deflation cycles with a 20 minute period coincident with strong explosions. These cycles represent the pressurization of the shallow conduit and explosive venting of overpressure that develops beneath a partially

  3. Spectral Analysis of the Signals Associated with Increased Activity in Popocatepetl Volcano April 2012

    NASA Astrophysics Data System (ADS)

    Cuenca, J.

    2013-05-01

    After several decades of being inactive in 1994 had a strong reactivation. Since then he has had long periods where volcanic activity including increased growth and destruction of a dome. In April 2012 Popocatepetl Volcano activity showed an increase in the emission of gas and ash, and Vulcanian type explosions. As a result the National Center for Disaster Prevention (CENAPRED) raised the yellow phase from 2 to 3. Spectrally analyzes seismic activity characteristic of the types of events (explosions, LP, Type-B and tremors) that provides information of the source processes that cause it, despite sustained change reflected by the complexity of the volcanic apparatus, through of: 1) the spectral content of the process provides the source, 2) the spectral ratio H / V, its associated amplification and dominant frequencies, 3) time frequency analysis showing the variation in frequency, 4) the particle motion to analyze its retrograde or prograde acting in a volcanic complex medium. The calculation of H / V was performed by each hour using windows with duration of 80 seconds in the broadband seismic station "Canario" (PPPB). The predominant frequencies of H / V are around 1.4-1.8 Hz to 2.1-2.6 Hz and amplifications from 2.3 to 6.9 times. Analysis of H / V of 48 hours (days 16 and April 17) for the case of 1.4-1.8 Hz was observed: (1) From 0-9 hours there is no amplification. (2) The seismic amplification increases from 10 to 11 hours. (3) A first crisis reaches a maximum at 13 hours with about 6 times of amplification. (4) From 14 to 15 hours there is a strong relaxation of the activity. (5) The activity begins to increase from 16 to 23 hours where it reaches its maximum amplification of almost 7 times. (6) The following two hours and is kept exceeding 6 times of amplification. (7) Then is followed by a decrease to 4 hours on the day 17, from which is maintained at a level variable. (8) At 18 hours of the day 17 grows the amplification at 6.2 times, which conforms a

  4. Bathymetry of southern Mauna Loa Volcano, Hawaii

    USGS Publications Warehouse

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

    1993-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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)

  6. Coupling of Activity at Neighbouring Volcanoes in Iceland: Ground Deformation and Activity at the Bárðarbunga-Tungnafellsjökull and Eyjafjallajökull-Katla Volcano Pairs

    NASA Astrophysics Data System (ADS)

    Parks, M.; Heimisson, E. R.; Sigmundsson, F.; Hooper, A. J.; Ofeigsson, B.; Vogfjord, K. S.; Arnadottir, T.; Dumont, S.; Drouin, V.; Bagnardi, M.; Spaans, K.; Hreinsdottir, S.; Friðriksdóttir, H. M.; Jonsdottir, K.; Guðmundsson, G.; Hensch, M.; Hjaltadottir, S.; Hjartardottir, A. R.; Einarsson, P.; Gudmundsson, M. T.; Hognadottir, T.; Lafemina, P.; Geirsson, H.; Sturkell, E.; Magnússon, E.

    2015-12-01

    Interferometric Synthetic Aperture Radar (InSAR) techniques are used to generate a time series of high-resolution deformation measurements, in the vicinity of two pairs of closely spaced volcanoes in Iceland: Bárðarbunga and Tungnafellsjökull, as well as Eyjafjallajökull and Katla. Following the declaration of Icelandic Volcanoes as a Permanent Geohazard Supersite in 2013, a considerable amount of SAR data was made available for both past and future satellite acquisitions, including new X-band images and historic C-band images. InSAR time series have been formed using these data and compared to other geodetic and microseismic measurements to determine the most likely processes responsible for recently observed deformation and/or seismicity. A comprehensive network of seismometers and continuous GPS stations are already deployed at these volcanoes and a series of campaign GPS measurements have been undertaken since 2010. We present an overview of the temporal variation in InSAR observations and these complementary field based measurements at Bárðarbunga and Tungnafellsjökull from 2014-2015 (covering the recent eruption at Holuhraun and contemporaneous slow collapse of the Bárðarbunga caldera), and Eyjafjallajökull and Katla volcanoes from 2010 onwards, after the 2010 explosive eruption of Eyjafjallajökull. We undertake a joint InSAR-GPS inversion using a Markov-chain Monte Carlo approach. The best-fit source geometries responsible for both the inflation of a 50 km long dyke and simultaneous deflation of the Bárðarbunga central volcano during the 2014-2015 unrest and eruption are found. Using these we calculate the stress changes associated with the Bárðarbunga deformation events and compare our results to the location of earthquake swarms in the vicinity of neighbouring Tungnafellsjökull, where seismic activity increased significantly following the onset of unrest at Bárðarbunga in August 2014. We also determine the optimal source parameters for

  7. Volcanic history of El Chichon Volcano (Chiapas, Mexico) during the Holocene, and its impact on human activity

    USGS Publications Warehouse

    Espindola, J.M.; Macias, J.L.; Tilling, R.I.; Sheridan, M.F.

    2000-01-01

    Before its devastating eruption in 1982, El Chichon Volcano was little known and did not appear on any listings of hazardous volcanoes. Subsequent geologic studies, based on stratigraphic and radiocarbon investigations, showed that at least three explosive eruptions had occurred previously at this volcano. In this paper, we present the result of recent studies on the stratigraphy of the volcano and new radiocarbon ages which show that at least 11 eruptions have taken place at El Chichon in the past 8000 years. Explosive events, most of them producing block-and-ash flow and surge deposits, occurred around 550, 900, 1250, 1500, 1600, 1900, 2000, 2500, 3100, 3700 and 7700 years BP. The juvenile products of these eruptions have a trachyandesitic composition with similar degree of evolution, as evidenced from their SiO2 abundance and depletion in MgO, CaO, TiO2, as well as trace and rare earth elements. This suggests segregation of olivine and orthopyroxene from the melt. Since human settlements in southeast Mexico and Central America can be traced as far back as approximately 2500 years BP, most of these events probably affected human activity. In fact, there are reports of pottery shards and other artifacts in deposits from the eruption of 1250 BP. Pottery fragments in deposits of an eruption that took place 2500 BP are also reported in this paper. Thus, the impact of the volcano on human activities has been frequent, with most of the repose intervals lasting between 100 to 600 years. The impact of the eruptions was probably of greater than local extent, because airfall tephra could reach distant sites and possibly even affect weather. The eruptive history of El Chichon also offers clues in the investigation of the Maya civilization. Several researchers have considered the volcano as an important factor in the answer to some intriguing questions such as the extensive use of volcanic ash in Late Classic Maya ceramics or, of greater importance, the causes of the

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

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy

    2010-01-01

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

  9. Mud Volcanoes - Analogs to Martian Cones and Domes (by the thousands !)

    NASA Astrophysics Data System (ADS)

    Allen, C.; Oehler, D.

    2010-12-01

    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 km2. 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

  10. Active sulfur cycling by diverse mesophilic and thermophilic microorganisms in terrestrial mud volcanoes of Azerbaijan.

    PubMed

    Green-Saxena, A; Feyzullayev, A; Hubert, C R J; Kallmeyer, J; Krueger, M; Sauer, P; Schulz, H-M; Orphan, V J

    2012-12-01

    Terrestrial mud volcanoes (TMVs) represent geochemically diverse habitats with varying sulfur sources and yet sulfur cycling in these environments remains largely unexplored. Here we characterized the sulfur-metabolizing microorganisms and activity in four TMVs in Azerbaijan. A combination of geochemical analyses, biological rate measurements and molecular diversity surveys (targeting metabolic genes aprA and dsrA and SSU ribosomal RNA) supported the presence of active sulfur-oxidizing and sulfate-reducing guilds in all four TMVs across a range of physiochemical conditions, with diversity of these guilds being unique to each TMV. The TMVs varied in potential sulfate reduction rates (SRR) by up to four orders of magnitude with highest SRR observed in sediments where in situ sulfate concentrations were highest. Maximum temperatures at which SRR were measured was 60°C in two TMVs. Corresponding with these trends in SRR, members of the potentially thermophilic, spore-forming, Desulfotomaculum were detected in these TMVs by targeted 16S rRNA analysis. Additional sulfate-reducing bacterial lineages included members of the Desulfobacteraceae and Desulfobulbaceae detected by aprA and dsrA analyses and likely contributing to the mesophilic SRR measured. Phylotypes affiliated with sulfide-oxidizing Gamma- and Betaproteobacteria were abundant in aprA libraries from low sulfate TMVs, while the highest sulfate TMV harboured 16S rRNA phylotypes associated with sulfur-oxidizing Epsilonproteobacteria. Altogether, the biogeochemical and microbiological data indicate these unique terrestrial habitats support diverse active sulfur-cycling microorganisms reflecting the in situ geochemical environment.

  11. The Alaska Volcano Observatory - Expanded Monitoring of Volcanoes Yields Results

    USGS Publications Warehouse

    Brantley, Steven R.; McGimsey, Robert G.; Neal, Christina A.

    2004-01-01

    Recent explosive eruptions at some of Alaska's 52 historically active volcanoes have significantly affected air traffic over the North Pacific, as well as Alaska's oil, power, and fishing industries and local communities. Since its founding in the late 1980s, the Alaska Volcano Observatory (AVO) has installed new monitoring networks and used satellite data to track activity at Alaska's volcanoes, providing timely warnings and monitoring of frequent eruptions to the aviation industry and the general public. To minimize impacts from future eruptions, scientists at AVO continue to assess volcano hazards and to expand monitoring networks.

  12. Monitoring Morphological Changes at Colima Volcano Crater and Explosive Activity in 2003

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nunez-Cornu, F.; Reyes-Davila, G.

    2003-12-01

    The Colima Volcano is located in the West of the Volcanic Mexican Belt, since February 10 1999 has presented an alternated efusive and explosive activity, which has generated constant morphological changes at the summit. As result of the several explosions occurred in 1999, 2000 and at the beginning of the year 2001, a new crater was formed with dimensions of 260 for 225 meters, and an average depth of 40 m. This crater began to be filled by the end of October 31, 2001 by a extrusion dome that reach an approximate volume 2 x 106 m3. In the first week of February 2002 this dome reach the edge of the crater, beginning to form lava flows by the western, northeastern, and south flanks. This effusive activity continued in 2002, and small gas emission and explosions were observed. In April 2003 the number of explosions and degassings became more frequent in the dome, this activity was registred by the seismic networks (RESCO and RESJAL) and recorded by video cameras located at Jalisco Civil Defense Nevado Base, 5 km away of the volcano. Aerial reconnaissance carried out in May 16 showed a complete change in the morphology of the dome as was observed in February 2002, identifying a new crater with a elipsoidal concave shape with approximate dimensions of 140 x 110 m and a depth in its central part of 15 mts. In the SE flank we observed another crater with similar form to the previous one whose dimensions are of 30 x 20 m with depth of 15 m, where continuous explosions have been appraised. At dawn of June 17, August 2 and 28, 2003 explosions happened that reached an altitude between 2000 and 3000 m, which were of smaller magnitude than happened the 22 of February of the 2000. These explosions were preceded of prolonged periods of tremor reported by RESCO. This explosive activity also present gas emission gas in form of jets, with duration from some seconds until more a than minute and altitude of approximate 500 meters, like the occurred on June 7, its point of emission

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

    PubMed

    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.

  14. Observed inflation-deflation cycles at Popocatepetl volcano using tiltmeters and its possible correlation with regional seismic activity in Mexico

    NASA Astrophysics Data System (ADS)

    Contreras Ruiz Esparza, M. G., Sr.; Jimenez Velazquez, J. C., Sr.; Valdes Gonzalez, C. M., Sr.; Reyes Pimentel, T. A.; Galaviz Alonso, S. A.

    2014-12-01

    Popocatepetl, the smoking mountain, is a stratovolcano located in central Mexico with an elevation of 5450 masl. The active volcano, close to some of the largest urban centers in Mexico - 60 km and 30 km far from Mexico City and Puebla, respectively - poses a high hazard to an estimated population of 500 thousand people living in the vicinity of the edifice. Accordingly, in July 1994 the Popocatepetl Volcanological Observatory (POVO) was established. The observatory is operated and supported by the National Center for Disaster Prevention of Mexico (CENAPRED), and is equipped to fully monitor different aspects of the volcanic activity. Among the instruments deployed, we use in this investigation two tiltmometers and broad-band seismometers at two sites (Chipiquixtle and Encinos), which send the information gathered continuously to Mexico City.In this research, we study the characteristics of the tiltmeters signals minutes after the occurrence of certain earthquakes. The Popocatepetl volcano starts inflation-deflation cycles due to the ground motion generated by events located at certain regions. We present the analysis of the tiltmeters and seismic signals of all the earthquakes (Mw>5) occurred from January 2013 to June 2014, recorded at Chipiquixtle and Encinos stations. First, we measured the maximum tilt variation after each earthquake. Next, we apply a band-pass filter for different frequency ranges to the seismic signals of the two seismic stations, and estimated the total energy of the strong motion phase of the seismic record. Finally, we compared both measurements and observed that the maximum tilt variations were occurring when the maximum total energy of the seismic signals were in a specific frequency range. We also observed that the earthquake records that have the maximum total energy in that frequency range were the ones with a epicentral location south-east of the volcano. We conclude that our observations can be used set the ground for an early

  15. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania

    USGS Publications Warehouse

    Kervyn, M.; Ernst, G.G.J.; Keller, J.; Vaughan, R. Greg; Klaudius, J.; Pradal, E.; Belton, F.; Mattsson, H.B.; Mbede, E.; Jacobs, P.M.

    2010-01-01

    On September 4, 2007, after 25 years of effusive natrocarbonatite eruptions, the eruptive activity of Oldoinyo Lengai (OL), N Tanzania, changed abruptly to episodic explosive eruptions. This transition was preceded by a voluminous lava eruption in March 2006, a year of quiescence, resumption of natrocarbonatite eruptions in June 2007, and a volcano-tectonic earthquake swarm in July 2007. Despite the lack of ground-based monitoring, the evolution in OL eruption dynamics is documented based on the available field observations, ASTER and MODIS satellite images, and almost-daily photos provided by local pilots. Satellite data enabled identification of a phase of voluminous lava effusion in the 2 weeks prior to the onset of explosive eruptions. After the onset, the activity varied from 100 m high ash jets to 2–15 km high violent, steady or unsteady, eruption columns dispersing ash to 100 km distance. The explosive eruptions built up a ∼400 m wide, ∼75 m high intra-crater pyroclastic cone. Time series data for eruption column height show distinct peaks at the end of September 2007 and February 2008, the latter being associated with the first pyroclastic flows to be documented at OL. Chemical analyses of the erupted products, presented in a companion paper (Keller et al.2010), show that the 2007–2008 explosive eruptions are associated with an undersaturated carbonated silicate melt. This new phase of explosive eruptions provides constraints on the factors causing the transition from natrocarbonatite effusive eruptions to explosive eruptions of carbonated nephelinite magma, observed repetitively in the last 100 years at OL.

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

    NASA Technical Reports Server (NTRS)

    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.

  17. 2012 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Herrick, Julie A.; Neal, Christina A.; Cameron, Cheryl E.; Dixon, James P.; McGimsey, Robert G.

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, or suspected unrest at 11 volcanic centers in Alaska during 2012. Of the two verified eruptions, one (Cleveland) was clearly magmatic and the other (Kanaga) was most likely a single phreatic explosion. Two other volcanoes had notable seismic swarms that probably were caused by magmatic intrusions (Iliamna and Little Sitkin). For each period of clear volcanic unrest, AVO staff increased monitoring vigilance as needed, reviewed eruptive histories of the volcanoes in question to help evaluate likely outcomes, and shared observations and interpretations with the public. 2012 also was the 100th anniversary of Alaska’s Katmai-Novarupta eruption of 1912, the largest eruption on Earth in the 20th century and one of the most important volcanic eruptions in modern times. AVO marked this occasion with several public events.

  18. Paint-Stirrer Submarine

    ERIC Educational Resources Information Center

    Young, Jocelyn; Hardy, Kevin

    2007-01-01

    In this article, the authors discuss a unique and challenging laboratory exercise called, the paint-stir-stick submarine, that keeps the students enthralled. The paint-stir-stick submarine fits beautifully with the National Science Education Standards Physical Science Content Standard B, and with the California state science standards for physical…

  19. Submarine cable route survey

    SciTech Connect

    Herrouin, G.; Scuiller, T.

    1995-12-31

    The growth of telecommunication market is very significant. From the beginning of the nineties, more and more the use of optical fiber submarine cables is privileged to that of satellites. These submarine telecommunication highways require accurate surveys in order to select the optimum route and determine the cable characteristics. Advanced technology tools used for these surveys are presented along with their implementation.

  20. Correlation of submarine deposits and witness accounts of the 1952 Myojinsho submarine eruption, Izu-Bonin arc, by bathymetric survey

    NASA Astrophysics Data System (ADS)

    Shimano, T.; Tani, K.; Maeno, F.; Fiske, R. S.; Shukuno, H.; Ito, K.; Shimoda, G.; Suzuki, Y. J.; Yoshida, T.; Taniguchi, H.

    2009-12-01

    The relationship between eruptive phenomena during the 1952 phreatomagmatic eruption and consequent deposits under seawater is discussed, on the basis of bathymetric survey of Myojinsho volcano, Izu-Bonin island arc (32°55’N, 140°00’E). We carried out some research cruises by the ship Natsushima (JAMSTEC) in 2006-2008. We used unmanned bathymetric vehicle, Hyperdolphin, for observation and sampling of the submarine deposit. Myojinsho volcano is an active post-caldera volcano that grew on the northeastern rim of Myojinsho caldera (8 x 6 km in diameter). There have been many reports of colored seawater, and we also recognized a bubbly column above the summit of Myojinsho (Myojin reef; ca. 50 m below sea level) during acoustic survey. The 1952 eruption was the latest eruption that formed and destroyed new island above sea level, and would have been the first submarine eruption to be recorded by good scientific standard. This eruption was firstly recognized at the middle of September, 1952, and explosions and dome growth have been documented for about 1 year till the middle of September, 1953. There are many time series color photographs of explosions so that we can evaluate these explosions quantitatively (Ossaka, 1991). These records indicate that most of the cock’s tail jets are limited within the proximal area (ca. 500m) from the center of explosions, whereas the base surges and lateral steam clouds reach farther than ca. 500 m. During the bathymetric survey, we found several small lobes of pumice-rich deposits (< 1 m thick, several meter wide, several tens of meter long) on the sandy flat slope father than ca. 500 m from the summit of Myojinsho (deeper than ca. 300 m below sea level). Large pumices are concentrated at the front of each lobe, and the lobes become thinner toward the summit. On the other hand, the proximal deposit (<500 m from the summit) is characterized by scattered large angular blocky rocks or pumices. The largest blocks are as large as

  1. Magmatically Greedy Reararc Volcanoes of the N. Tofua Segment of the Tonga Arc

    NASA Astrophysics Data System (ADS)

    Rubin, K. H.; Embley, R. W.; Arculus, R. J.; Lupton, J. E.

    2013-12-01

    Volcanism along the northernmost Tofua Arc is enigmatic because edifices of the arc's volcanic front are mostly, magmatically relatively anemic, despite the very high convergence rate of the Pacific Plate with this section of Tonga Arc. However, just westward of the arc front, in terrain generally thought of as part of the adjacent NE Lau Backarc Basin, lie a series of very active volcanoes and volcanic features, including the large submarine caldera Niuatahi (aka volcano 'O'), a large composite dacite lava flow terrain not obviously associated with any particular volcanic edifice, and the Mata volcano group, a series of 9 small elongate volcanoes in an extensional basin at the extreme NE corner of the Lau Basin. These three volcanic terrains do not sit on arc-perpendicular cross chains. Collectively, these volcanic features appear to be receiving a large proportion of the magma flux from the sub-Tonga/Lau mantle wedge, in effect 'stealing' this magma flux from the arc front. A second occurrence of such magma 'capture' from the arc front occurs in an area just to the south, on southernmost portion of the Fonualei Spreading Center. Erupted compositions at these 'magmatically greedy' volcanoes are consistent with high slab-derived fluid input into the wedge (particularly trace element abundances and volatile contents, e.g., see Lupton abstract this session). It is unclear how long-lived a feature this is, but the very presence of such hyperactive and areally-dispersed volcanism behind the arc front implies these volcanoes are not in fact part of any focused spreading/rifting in the Lau Backarc Basin, and should be thought of as 'reararc volcanoes'. Possible tectonic factors contributing to this unusually productive reararc environment are the high rate of convergence, the cold slab, the highly disorganized extension in the adjacent backarc, and the tear in the subducting plate just north of the Tofua Arc.

  2. Structure and deformation of the Southern Taiwan accretionary prism: The active submarine Fangliao Fault Zone offshore west Hengchun Peninsula

    NASA Astrophysics Data System (ADS)

    Deffontaines, Benoit; Liu, Char-Shine; Hsu, Ho-Han

    2016-12-01

    What is the structural geometry of the southern Taiwan transition zone from the Manila subduction offshore to the Taiwan onshore collision, specifically in the western flank of the Hengchun peninsula that corresponds to the summit of the Manila subduction accretionary prism? This paper aims to decipher the onshore/offshore structures and tectonic deformation that occur west of the Hengchun Ridge through both detailed topographic analyses and interpretation of numerous old and new seismic profiles. From a geomorphic point of view, both Fangliao and Hongchai submarine canyons have different structural and landslide implications. The Fangliao Canyon is guided by a N-S elongated mud diapir (the Fangliao Ridge), intruding an inferred N010°E trending, left lateral strike-slip fault zone. Conversely, the arcuate and concave shape of the Hongchai Canyon appear to follow the crown and the northern boundary of a newly recognized Hongchai submarine landslide situated on the steep western flank of the onshore asymmetric Hengchun Anticline. Our results highlight that both Fangliao and Hengchun Faults are linear, near-vertical left-lateral strike-slip faults. They converge onshore to the Chaochou Fault. This study demonstrates that neotectonics combine with morphostructural analysis of the submarine canyon drainages lead to a better comprehension of the present deformation in the northern part of the Manila accretionary prism.

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

    PubMed

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

    PubMed Central

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

    2016-01-01

    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 × 106 m3 to 7 × 106 m3. However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [−0.8;−0.4] × 109 kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 109 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. PMID:27629497

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

    NASA Astrophysics Data System (ADS)

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond D’Ars, Jean; Komorowski, Jean-Christophe

    2016-09-01

    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 × 106 m3 to 7 × 106 m3. However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [‑0.8‑0.4] × 109 kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 109 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.

  6. Provenance of a large Lower Cretaceous turbidite submarine fan complex on the active Laurasian margin: Central Pontides, northern Turkey

    NASA Astrophysics Data System (ADS)

    Akdoğan, Remziye; Okay, Aral I.; Sunal, Gürsel; Tari, Gabor; Meinhold, Guido; Kylander-Clark, Andrew R. C.

    2017-02-01

    The Pontides formed the southern active margin of Laurasia during the Mesozoic. They became separated from mainland Laurasia during the Late Cretaceous, with the opening of the Black Sea as an oceanic back-arc basin. During the Early Cretaceous, a large submarine turbidite fan complex developed in the Central Pontides. The turbidites cover an area of 400 km by 90 km with a thickness of more than 2 km. We have investigated the provenance of these turbidites-the Çağlayan Formation-using paleocurrent measurements, U-Pb detrital zircon ages, REE abundances of dated zircons and geochemistry of detrital rutile grains. 1924 paleocurrent measurements from 96 outcrop stations indicate flow direction from northwest to southeast in the eastern part of the Çağlayan Basin and from north-northeast to west-southwest in the western part. 1194 detrital zircon ages from 13 Lower Cretaceous sandstone samples show different patterns in the eastern, central and western parts of the basin. The majority of the U-Pb detrital zircon ages in the eastern part of the basin are Archean and Paleoproterozoic (61% of all zircon ages, 337 grains); rocks of these ages are absent in the Pontides and present in the Ukrainian Shield, which indicates a source north of the Black Sea. In the western part of the basin the majority of the zircons are Carboniferous and Neoproterozoic (68%, 246 grains) implying more local sources within the Pontides. The detrital zircons from the central part show an age spectrum as mixture of zircons from western and eastern parts. Significantly, Jurassic and Early Cretaceous zircons make up less than 2% of the total zircon population, which implies lack of a coeval magmatic arc in the region. This is compatible with the absence of the Lower Cretaceous granites in the Pontides. Thus, although the Çağlayan Basin occupied a fore-arc position above the subduction zone, the arc was missing, probably due to flat subduction, and the basin was largely fed from the Ukrainian

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

    NASA Astrophysics Data System (ADS)

    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

  8. Remote sensing of Italian volcanos

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  9. Cinnabar, arsenian pyrite and thallium-enrichment in active shallow submarine hydrothermal vents at Paleochori Bay, Milos Island, Greece

    NASA Astrophysics Data System (ADS)

    Kati, Marianna; Voudouris, Panagiotis; Valsami-Jones, Eugenia; Magganas, Andreas; Baltatzis, Emmanouil; Kanellopoulos, Christos; Mavrogonatos, Constantinos

    2015-04-01

    We herein report the discovery of active cinnabar-depositing hydrothermal vents in a submarine setting at Paleochori Bay, within the offshore southeastern extension of the Milos Island Geothermal Field, South Aegean Active Volcanic Arc. Active, low temperature (up to 115 °C) hydrothermal venting through volcaniclastic material has led to a varied assemblage of sulfide and alteration mineral phases in an area of approximately 1 km2. Our samples recovered from Paleochori Bay are hydrothermal edifices composed of volcaniclastic detrital material cemented by pyrite, or pure sulfide (mainly massive pyrite) mounts. Besides pyrite and minor marcasite, the hydrothermal minerals include cinnabar, amorphous silica, hydrous ferric oxides, carbonates (aragonite and calcite), alunite-jarosite solid solution and Sr-rich barite. Among others, growth textures, sieve-textured pyrite associated with barite, alunite-jarosite solid solution and hydrous ferric oxides rims colloform-banded pyrite layers. Overgrowths of arsenian pyrite layers (up to 3.2 wt. % As and/or up to 1.1 wt. % Mn) onto As-free pyrite indicate fluctuation in As content of the hydrothermal fluid. Mercury, in the form of cinnabar, occurs in up to 5 μm grains within arsenian pyrite layers, usually forming distinct cinnabar-enriched micro-layers. Hydrothermal Sr-rich barite (barite-celestine solid solution), pseudocubic alunite-jarosite solid solution and Mn- and Sr-enriched carbonates occur in various amounts and closely associated with pyrite and/or hydrous ferric oxides. Thallium-bearing sulfides and/or sulfosalts were not detected during our study; however, hydrous ferric oxides show thallium content of up to 0.5 wt. % Tl. The following scenarios may have played a role in pyrite precipitation at Paleochori: (a) H2S originally dissolved in the deep fluid but separated upon boiling could have reacted with oxygenated seawater under production of sulphuric acid, thus causing leaching and dissolution of primary iron

  10. Observations of Io's Active Volcanoes from IRTF: Imaging and Occultation Lightcurves

    NASA Astrophysics Data System (ADS)

    Rathbun, J. A.; Spencer, J. R.

    2014-12-01

    We have been observing Ionian volcanism from NASA's Infrared Telescope Facility (IRTF) for more than two decades. The frequency of our observations increases dramatically when spacecraft are observing Io in order to complement the data returned by the spacecraft. The Japanese Space Agency's (JAXA) Hisaki (Sprint-A) mission recently observd the Jupiter system from earth orbit, monitoring the Io Plasma Torus and Jovian aurora. In order to investigate the possible influence of Io volcanism on the torus, we observed Io's volcanoes from the IRTF in Hawaii between September 2013 and May 2014. We imaged Io at 2.2, 3.5, and 4.8 microns in eclipse and reflected sunlight. We also observed Io during occultation by Jupiter, which allows us to locate and characterize individual volcanic eruptions, with greater spatial accuracy, on the Jupiter-facing hemisphere. The 2013 3.5 micron images of a sunlit Io showed no obvious bright volcanic features. However, further increases in spatial resolution is possible with shift-and-add processing of short exposure images. Preliminary occultation lightcurves from 2013 show moderate levels of activity at Kaneheliki/Janus and Loki, the two volcanic centers most often observed in occultation lightcurves. Loki was much brighter in 2013 than during the New Horizons flyby in 2007, but not as bright as during the Galileo era (see figure). From February 2014 through May 2014, due to a planned upgrade on the SPEX instrument and an unplanned required repair on the NSFCam2 instrument (both of which we have used previously), we exclusively used the CSHELL instrument as an imager. Unfortunately, CSHELL was not designed for imaging and has limited spatial resolution and photometric precision, complicating image analysis.

  11. Waters associated with an active basaltic volcano, Kilauea, Hawaii: Variation in solute sources, 1973-1991

    USGS Publications Warehouse

    Tilling, R.I.; Jones, B.F.

    1996-01-01

    Chemical and isotopic analyses of samples collected from a 1262-m-deep research borehole at the summit of Kilauea Volcano provide unique time-series data for composition of waters in the uppermost part of its hydrothermal system. These waters have a distinctive geochemical signature: a very low proportion of chloride relative to other anions compared with other Hawaiian wa-ters - thermal (???30 ??C) or nonthermal (<30 ??C) - and with most thermal waters of the world. Isotope data demonstrate that the borehole waters are of essentially meteoric origin, with minimal magmatic input. The water chemistry exhibits marked temporal variations, including pronounced short-term (days to weeks) effects of rainfall dilution and longer term (months to years) decline of total solutes. The 1973-1974 samples are Na-sulfate-dominant, but samples collected after July 1975 are (Mg + Ca)-bicarbonate-dominant. This compositional shift, probably abrupt, was associated with an increase in the partial pressure of CO2 (PCO2) related to volcanic degassing of CO2 accompanying a large eruption (December 31, 1974) and associated intense seismicity. Following the initial sharp increase, the PCO2 then decreased, approaching preemption values in April 1976. Beginning in mid-1975, solute concentrations of the borehole waters decreased substantially, from ???45 meq/L to <25 meq/L in only eight months; by 1991, total solute concentrations were <17 meq/L. This decline in solutes cannot be attributed to rainfall dilution and is inferred to reflect the decreasing availability with time of the easily leachable salts of alkali metals and sulfate, which originated in sublimates and fumarolic encrustations in fractures and cavities of rocks along the hydrologic flow paths. The overall chemistry of the summit-borehole waters is largely determined by hydrolysis reactions associated with normal weathering of host tholeiitic basalts on a geologic time scale, despite short-term perturbations in composition

  12. Buried Rift Zones and Seamounts in Hawaii: Implications for Volcano Tectonics

    NASA Astrophysics Data System (ADS)

    Park, J.; Morgan, J. K.; Zelt, C. A.; Okubo, P. G.

    2005-12-01

    below sea level), the high velocities are sharply truncated to the south. However, at greater depths, the anomalously high velocities extend another 20 km into the submarine flank, distinguishing this feature as a once extensive rift zone. The presence of dense, coherent intrusive rock may have anchored Mauna Loa's southeastern flank, such that much of the volcano's recent deformation has occurred along the west flank of Mauna Loa. This massive rift zone may also impede the propagation of Kilauea's southwest rift zone, accounting for its lesser development relative to Kilauea's east rift zone. The velocity highs beneath Kilauea's submarine flank likely represent buried seamounts that might obstruct the seaward migration of volcano's south flank, causing the bench uplift at the toe of flank. These new observations lead us to propose that previously unrecognized intrusive complexes within Mauna Loa and Kilauea have significantly affected the past evolution of these volcanoes in the Island of Hawaii, and are likely responsible for the present patterns of deformation on these active volcanoes.

  13. Acoustic measurements of the 1999 basaltic eruption of Shishaldin volcano, Alaska 1. Origin of Strombolian activity

    USGS Publications Warehouse

    Vergniolle, S.; Boichu, M.; Caplan-Auerbach, J.

    2004-01-01

    The 1999 basaltic eruption of Shishaldin volcano (Alaska, USA) displayed both classical Strombolian activity and an explosive Subplinian plume. Strombolian activity at Shishaldin occurred in two major phases following the Subplinian activity. In this paper, we use acoustic measurements to interpret the Strombolian activity. Acoustic measurements of the two Strombolian phases show a series of explosions that are modeled by the vibration of a large overpressurised cylindrical bubble at the top of the magma column. Results show that the bubble does not burst at its maximum radius, as expected if the liquid film is stretched beyond its elasticity. But bursting occurs after one cycle of vibration, as a consequence of an instability of the air-magma interface close to the bubble minimum radius. During each Strombolian period, estimates of bubble length and overpressure are calculated. Using an alternate method based on acoustic power, we estimate gas velocity to be 30-60 m/s, in very good agreement with synthetic waveforms. Although there is some variation within these parameters, bubble length and overpressure for the first Strombolian phase are found to be ??? 82 ?? 11 m and 0.083 MPa. For the second Strombolian phase, bubble length and overpressure are estimated at 24 ?? 12 m and 0.15 MPa for the first 17 h after which bubble overpressure shows a constant increase, reaching a peak of 1.4 MPa, just prior to the end of the second Strombolian phase. This peak suggests that, at the time, the magma in the conduit may contain a relatively large concentration of small bubbles. Maximum total gas volume and gas fluxes at the surface are estimated to be 3.3 ?? 107 and 2.9 ?? 103 m3/s for the first phase and 1.0 ?? 108 and 2.2 ?? 103 m3/s for the second phase. This gives a mass flux of 1.2 ?? 103 and 8.7 ?? 102 kg/s, respectively, for the first and the second Strombolian phases. ?? 2004 Elsevier B.V. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    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

  15. Seismic structure and origin of active intraplate volcanoes in Northeast Asia

    NASA Astrophysics Data System (ADS)

    Duan, Yonghong; Zhao, Dapeng; Zhang, Xiankang; Xia, Shaohong; Liu, Zhi; Wang, Fuyun; Li, Li

    2009-05-01

    Three-dimensional P-wave velocity structure beneath the Changbai and other intraplate volcanic areas in Northeast Asia is determined by inverting 1378 high-quality P-wave arrival times from 186 teleseismic events recorded by 61 broadband seismic stations. Low-velocity (low-V) anomalies are revealed beneath the Changbai, Longgan, Xianjindao volcanoes. High-velocity (high-V) anomalies are found in the mantle transition zone, where deep-focus earthquakes under Hunchun occur at depths of 500-600 km. The high-V anomaly reflects the deep subduction of the Pacific slab under NE Asia which may have contributed to the formation of the Changbai, Longgang, Xianjindao and Jingpohu intraplate volcanoes. A low-V anomaly is also revealed in the mantle transition zone, which may have a close relationship with the occurrence of deep earthquakes under the Hunchun area. Our results support the Big Mantle Wedge (BMW) model by Zhao et al. [Zhao, D., Lei, J., Tang, Y., 2004. Origin of the Changbai volcano in northeast China: evidence from seismic tomography, Chin. Sci. Bull. 49, 1401-1408; Zhao, D., Maruyama, S., Omori, S., 2007. Mantle dynamics of western Pacific and East Asia: insight from seismic tomography and mineral physics. Gondwana Res. 11, 120-131.] who proposed that the intraplate volcanoes in NE Asia are caused by the back-arc magmatism associated with the deep dehydration process of the subducting slab and convective circulation process in the BMW above the stagnant Pacific slab.

  16. Discovery of Active Hydrothermal Sites Along the Mariana Volcanic Arc, Western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Baker, E. T.; Embley, R. W.; Resing, J. A.; Lupton, J. E.; Massoth, G. J.; de Ronde, C. E.; Nakamura, K.; Walker, S. L.

    2003-12-01

    Some 20,000 km of volcanic arcs, roughly one-third the total length of the global midocean ridge (MOR) system, rim the western Pacific Ocean. But compared to 25 years of hydrothermal investigations along MORs, exploration of similar activity on the estimated 600 submarine arc volcanoes is only beginning. In February 2003, as part of the Submarine Ring of Fire project funded by NOAA's Ocean Exploration Program, we made the first systematic survey of hydrothermal activity along the 1270-km-long Mariana intraoceanic volcanic arc, which lies almost entirely within the US EEZ. Prior fieldwork had documented active (but low-temperature) hydrothermal discharge on only three volcanoes: Kasuga 2, Kasuga 3, and Esmeralda Bank. During the cruise, we conducted 70 CTD operations over more than 50 individual volcanoes from 13° N to 23° N, plus a continuous CTD survey along 75 km of the back-arc spreading center (13° 15'N to 13° 41'N) adjacent to the southern end of the arc. We found evidence for active hydrothermal venting at 11 submarine volcanoes with summit (or caldera floor) depths ranging from 50 to 1550 m. Two additional sites were identified on the back-arc spreading center. Ongoing analyses of collected water samples could increase these totals. Our results confirmed continuing hydrothermal activity at Kasuga 2 (but not Kasuga 3) and Esmeralda Bank, in addition to newly discovered sites on nine other volcanoes. Many of these sites produce intense and widely dispersed plumes indicative of vigorous, high-temperature discharge. The volcanoes with active hydrothermal systems are about equally divided between those with and without summit calderas. The addition of the Marianas data greatly improves our view of hydrothermal sources along arcs. The 20,000 km of Pacific arcs can be divided between 6380 km of intraoceanic (i.e., mostly submarine) arcs and 13,880 km of island (i.e., mostly subaerial) arcs. At present, ˜15% of the total length of Pacific arcs has been surveyed

  17. Prevalence of Helicobacter pylori in United States Navy submarine crews.

    PubMed

    Jackman, R P; Schlichting, C; Carr, W; Dubois, A

    2006-06-01

    Helicobacter pylori prevalence is elevated in German submarine crews and in United States Navy (USN) surface fleet personnel, but H. pylori prevalence in USN submariners was unknown. The goal of the study was to determine the prevalence of H. pylori in the crews of USN nuclear submarines compared to other military personnel and to the general US population. The presence of H. pylori IgG antibodies was determined in serum samples using a commercial ELISA. Only 47 out of 451 submariners (9.4%) were H. pylori positive, which is similar to that of the US general population with a similar level of education. In contrast, H. pylori prevalence is significantly higher in US Army recruits (26%), USN surface fleet personnel (25%), and German diesel submariners (38%). These data demonstrate that submarine service (and by inference activity requiring isolation and close contact, per se) is not a risk factor for H. pylori infection.

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

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  19. Volcano-hazard zonation for San Vicente volcano, El Salvador

    USGS Publications Warehouse

    Major, J.J.; Schilling, S.P.; Pullinger, C.R.; Escobar, C.D.; Howell, M.M.

    2001-01-01

    San Vicente volcano, also known as Chichontepec, is one of many volcanoes along the volcanic arc in El Salvador. This composite volcano, located about 50 kilometers east of the capital city San Salvador, has a volume of about 130 cubic kilometers, rises to an altitude of about 2180 meters, and towers above major communities such as San Vicente, Tepetitan, Guadalupe, Zacatecoluca, and Tecoluca. In addition to the larger communities that surround the volcano, several smaller communities and coffee plantations are located on or around the flanks of the volcano, and major transportation routes are located near the lowermost southern and eastern flanks of the volcano. The population density and proximity around San Vicente volcano, as well as the proximity of major transportation routes, increase the risk that even small landslides or eruptions, likely to occur again, can have serious societal consequences. The eruptive history of San Vicente volcano is not well known, and there is no definitive record of historical eruptive activity. The last significant eruption occurred more than 1700 years ago, and perhaps long before permanent human habitation of the area. Nevertheless, this volcano has a very long history of repeated, and sometimes violent, eruptions, and at least once a large section of the volcano collapsed in a massive landslide. The oldest rocks associated with a volcanic center at San Vicente are more than 2 million years old. The volcano is composed of remnants of multiple eruptive centers that have migrated roughly eastward with time. Future eruptions of this volcano will pose substantial risk to surrounding communities.

  20. Submarine neutrino communication

    NASA Astrophysics Data System (ADS)

    Huber, Patrick

    2010-09-01

    We discuss the possibility to use a high energy neutrino beam from a muon storage ring to provide one way communication with a submerged submarine. Neutrino interactions produce muons which can be detected either, directly when they pass through the submarine or by their emission of Cerenkov light in sea water, which, in turn, can be exploited with sensitive photo detectors. Due to the very high neutrino flux from a muon storage ring, it is sufficient to mount either detection system directly onto the hull of the submersible. The achievable data transfer rates compare favorable with existing technologies and do allow for a communication at the usual speed and depth of submarines.

  1. Explosive eruptive activity and temporal magmatic changes at Yotei Volcano during the last 50,000 years, southwest Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Uesawa, Shimpei; Nakagawa, Mitsuhiro; Umetsu, Akane

    2016-10-01

    To understand the eruptive history, structure, and magmatic evolution of Yotei Volcano, southwest Hokkaido, Japan, we investigated the geology and petrology of tephras located around the base of the volcano. We identified 43 tephra units interbedded with soils (in descending stratigraphic order, tephras Y1-Y43), and four widespread regional tephras. Ten radiocarbon ages were obtained from soils beneath the Yotei tephras. On the basis of petrologic differences and, the stratigraphic positions of thick layers of volcanic ash soil, indicative of volcanic stratigraphic gaps, the Yotei tephras are divided into four groups (in ascending stratigraphic order): Yotei tephra groups I, II-1, II-2, and II-3. We calculated the age of each eruptive deposit based on the soil accumulation rate, and estimated the volume of each eruption using isopach maps or the correlation between eruption volume and the maximum thickness at ~ 10 km from the summit crater. The results regarding eruptive activity and the rate of explosive eruptions indicate four eruptive stages at Yotei Volcano over the last 50,000 years. Stage I eruptions produced Yotei tephra group I between ca. 54 cal. ka BP and up to at least ca. 46 cal. ka BP, at relatively high average eruption rates of 0.07 km3 dense-rock equivalent (DRE)/ky. After a pause in activity of ca. 8000 years, Stage II-1 to II-2 eruptions produced Yotei tephra groups II-1 and II-2 from ca. 38 to ca. 21 cal. ka BP at high average eruption rates (0.10 km3 DRE/ky), after a pause in activity of 2000-3000 years. Finally, after another pause in activity of 4000-5000 years, Stage II-3 eruptions produced Yotei tephra group II-3 from ca. 16.5 cal. ka BP until the present day, at low average eruption rates (0.009 km3 DRE/ky). Whole-rock geochemical compositions vary within each tephra group over the entire eruption history. For example, group I and II-3 tephras contain the lowest and highest abundances, respectively, of K2O, P2O5, and Zr. Group II-1 has the

  2. Characterization of volcanic activity using observations of infrasound, volcanic emissions, and thermal imagery at Karymsky Volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Lopez, T.; Fee, D.; Prata, F.

    2012-04-01

    Karymsky Volcano is one of the most active and dynamic volcanoes in Kamchatka, with activity ranging from vigorous degassing, frequent ash emissions, and apparent vent sealing, all punctuated by daily to weekly explosive magmatic eruptions. Recent studies have highlighted the strengths in using complementary infrasound measurements and remote volcanic emission measurements to characterize volcanic activity, with the potential to discriminate emission-type, approximate ash-cloud height, and estimate SO2 emission mass. Here we use coincident measurements of infrasound, SO2, ash, and thermal radiation collected over a ten day period at Karymsky Volcano in August 2011 to characterize the observed activity and elucidate vent processes. The ultimate goal of this project is to enable different types of volcanic activity to be identified using only infrasound data, which would significantly improve our ability to continuously monitor remote volcanoes. Four types of activity were observed. Type 1 activity is characterized by discrete ash emissions occurring every 1 - 5 minutes that either jet or roil out of the vent, by plumes from 500 - 1500 m (above vent) altitudes, and by impulsive infrasonic onsets. Type 2 activity is characterized by periodic pulses of gas emission, little or no ash, low altitude (100 - 200 m) plumes, and strong audible jetting or roaring. Type 3 activity is characterized by sustained emissions of ash and gas, with multiple pulses lasting from ~1 - 3 minutes, and by plumes from 300 - 1500 m. Type 4 activity is characterized by periods of relatively long duration (~30 minutes to >1 hour) quiescence, no visible plume and weak SO2 emissions at or near the detection limit, followed by an explosive, magmatic eruption, producing ash-rich plumes to >2000 m, and centimeter to meter (or greater) sized pyroclastic bombs that roll down the flanks of the edifice. Eruption onset is accompanied by high-amplitude infrasound and occasionally visible shock

  3. Submarine volcanic features west of Kealakekua Bay, Hawaii

    USGS Publications Warehouse

    Fornari, D.J.; Lockwood, J.P.; Lipman, P.W.; Rawson, M.; Malahoff, A.

    1980-01-01

    Visual observations of submarine volcanic vents were made from the submersible vehicle DSV "Sea Cliff" in water depths between 1310 and 690 m, west of Kealakekua Bay, Hawaii. Glass-rich, shelly submarine lavas surround circular 1- to 3-m-diameter volcanic vents between 1050 and 690 m depth in an area west-northwest of the southernpoint (Keei Pt.) of Kealakekua Bay. Eye-witness accounts indicate that this area was the site of a submarine eruption on February 24, 1877. Chemical analyses of lavas from these possible seafloor vent areas indicate that the eruptive products are very similar in composition to volcanic rocks produced by historic eruptions of Mauna Loa volcano. ?? 1980.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  5. [The health status and morbidity in the crew members of submarines at different periods of combat training activity].

    PubMed

    Bortnovskiĭ, V N; Myznikov, I L

    1993-09-01

    It was found out in the result of complex examination of health status of 2020 enlisted men from 65 submarine crews of the North Fleet, that the inflammatory and infectious morbidity during the post-cruise period was considerably higher than during seagoing period. This morbidity was characterized by seasonal outbreaks. As for the types of the immune dependency, there were no seasonal changes. The peak of infectious morbidity coincides with the pre-cruise preparative period and post-cruise recreation due to "mixing" of the crews and diminishing of the non-specific resistance of an organism.

  6. State of the hydrothermal activity of Soufrière of Guadeloupe volcano inferred by VLF surveys

    NASA Astrophysics Data System (ADS)

    Zlotnicki, J.; Vargemezis, G.; Mille, A.; Bruère, F.; Hammouya, G.

    2006-04-01

    La Soufrière (1467 m) is the active island arc volcano of Guadeloupe Island in the Lesser Antilles arc. Its historical eruptions are more or less violent phreatic outbursts the last of which, in 1976-1977, led to the evacuation of nearly 70 000 persons. The subsurface structure of the volcano consists of calderas, craters, and avalanche amphitheatres nested within the composite pile of eruptive products. Since the last magmatic eruption, dated ca. 1440 AD, the four phreatic eruptions have developed radial fractures on Soufrière dome favouring the development of a huge active hydrothermal system emphasized by a tropical environment. After the eruptions, the thermal state and the stable ground water flow are completely disorganised during several years during which the slow mineralization of rocks is becoming again preponderant. Sealing of fractures and decay of rocks permeability act as a cap for upward thermal transfers. Therefore Soufrière dome operates as a valve, resealing the hydrothermal system underlying the volcano thus providing over pressurization that could lead to the next phreatic eruption. In 1992 new small seismic swarms have appeared. Several of them are recorded every year while the emission of acid gas slowly increases. In order to recognise the superficial electrical resistive and conductive zones (less than 100 m depth) as well as the cavities on Soufrière volcano, we have made Very Low Frequency (VLF) surveys in 2000. Electrical conductive zones are clearly associated with major radial faults starting from the summit in which the hydrothermal activity takes place. In the continuation of these active hydrothermal fractures hot springs are located down slope. Conversely some of the resistive zones are associated with inactive clayed and sealed or opened faults. The distribution of the conductive zones allows detailing the state of the superficial part of the hydrothermal system of La Soufrière. The distribution of vertical clayed zones

  7. What more have we learned from thermal infrared remote sensing of active volcanoes other than they are hot? (Invited)

    NASA Astrophysics Data System (ADS)

    Ramsey, M.

    2009-12-01

    Thermal infrared (TIR) remote sensing has been used for decades to detect changes in the heat output of active and reawakening volcanoes. The data from these thermally anomalous pixels are commonly used either as a monitoring tool or to calculate parameters such as effusion rate and eruptive style. First and second generation TIR data have been limited in the number of spectral channels and/or the spatial resolution. Two spectral channels with only one km spatial resolution has been the norm and therefore the number of science applications is limited to very large or very hot events. The one TIR channel of the Landsat ETM+ instrument improved the spatial resolution to 60 m, but it was not until the launch of ASTER in late 1999 that orbital TIR spectral resolution increased to five channels at 90 m per pixel. For the first time, the ability existed to capture multispectral emitted radiance from volcanic surfaces, which has allowed the extraction of emissivity as well as temperature. Over the past decade ASTER TIR emissivity data have been examined for a variety of volcanic processes including lava flow emplacement at Kilauea and Kluichevskoi, silicic lava dome composition at Sheveluch, Bezymianny and Mt. St. Helens, low temperature fumaroles emissions at Cerro Negro, and textural changes on the pyroclastic flow deposits at Merapi, Sheveluch and Bezymianny. Thermal-temporal changes at the 90 m scale are still an important monitoring tool for active volcanoes using ASTER TIR data. However, the ability to extract physical parameters such as micron-scale roughness and bulk mineralogy has added tremendously to the science derived from the TIR region. This new information has also presented complications such as the effects of sub-pixel thermal heterogeneities and amorphous glass on the emissivity spectra. If better understood, these complications can provide new insights into the physical state of the volcanic surfaces. Therefore, new data processing algorithms

  8. Fossil Foraminifera from four active mud volcanoes in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Kohl, Barry; Roberts, Harry H.

    1994-06-01

    Samples were collected for foraminiferal studies by the Johnson Sea-Link I and II manned submersibles on the Louisiana continental slope. This paper documents that the mud, extruded onto the sea floor from depth by four mud volcanoes, ranges in age from Miocene to Pleistocene based on studies of the planktonic foraminiferal fauna. The vents are in water depths ranging from 300 to 690 m located in Garden Banks Block 382, Green Canyon Blocks 143 and 272, and Mississippi Canyon Block 929. Two mud volcanoes in GB 382 and MC 929 also have rich fossil foraminiferal microfaunas. We suggest that the extrusion of fossil sediments onto the sea floor during the Quaternary is a reasonable explanation for frequent occurrences of displaced fossil microfaunas encountered at depth in wells drilling on the flanks of salt diapirs in the slope environment. Results of this study have important implications for age dating subsurface sediments in bathyal locations.

  9. Chronology of Postglacial Eruptive Activity and Calculation of Eruption Probabilities for Medicine Lake Volcano, Northern California

    USGS Publications Warehouse

    Nathenson, Manuel; Donnelly-Nolan, Julie M.; Champion, Duane E.; Lowenstern, Jacob B.

    2007-01-01

    Medicine Lake volcano has had 4 eruptive episodes in its postglacial history (since 13,000 years ago) comprising 16 eruptions. Time intervals between events within the episodes are relatively short, whereas time intervals between the episodes are much longer. An updated radiocarbon chronology for these eruptions is presented that uses paleomagnetic data to constrain the choice of calibrated ages. This chronology is used with exponential, Weibull, and mixed-exponential probability distributions to model the data for time intervals between eruptions. The mixed exponential distribution is the best match to the data and provides estimates for the conditional probability of a future eruption given the time since the last eruption. The probability of an eruption at Medicine Lake volcano in the next year from today is 0.00028.

  10. Submarine Landslides: What we Know and Where we are Going!

    NASA Astrophysics Data System (ADS)

    Moscardelli, L. G.; Mountjoy, J. J.; Micallef, A.; Strasser, M.; Vanneste, M.; Chaytor, J. D.; Mosher, D.; Krastel, S.; Lo Iacono, C.; Yamada, Y.

    2015-12-01

    Submarine landslides and other gravity-induced movements can disrupt very large areas of continental margins resulting in long-term seafloor morphologic change and multi-scale mass transport deposits (MTDs). Potential consequences of submarine landslides include damage to seabed infrastructure, offshore facilities, as well as generation or enhancement of tsunamis. MTDs are common on the modern seafloor and within the stratigraphic record. Slides, slumps and debris flows can be constituents of MTDs and can co-occur in the same event or depositional unit. Recent research indicates that relationships exist between MTD geological setting, causal mechanisms, and geometries. Quantitative data analysis suggests that MTD morphometric parameters can be used to link these three parameters. Despite many advances in this field, it still remains unclear how to definitively identify pre-conditioning factors and triggers of submarine landslides in modern slopes, and how submarine landslides evolve after initiation. In addition, new questions regarding the interaction between submarine landslides and active marine processes, such as bottom currents and fluid flow, have emerged.One of the mandates of the S4SLIDE (IGCP-640) project, a joint endeavor of UNESCO and IGCP that represents the broad field of submarine landslide research, is to facilitate interactions at an international level among scientists, industry and government representatives to advance our knowledge on a number of outstanding science questions: (i) What is the nature of the interaction between current-controlled sedimentation and submarine landslides? (ii) What role do transient turbulent-laminar flows play in the formation of submarine landslides? (iii) Do climatic variations control the occurrence of submarine landslides? (iv) What is the economic significance of submarine landslides? (v) Do we understand the hazards that submarine landslides pose to the environment and to humans? This presentation will cover

  11. Satellite relay telemetry in the surveillance of active volcanoes and major fault zones

    NASA Technical Reports Server (NTRS)

    Eaton, J. P.; Ward, P. L.

    1972-01-01

    A review was made of efforts to develop a dense telemetered microearthquake network to study earthquake mechanics along the San Andreas fault and the strain mechanics of the Kilauea Volcano. The principle elements and objectives of the ERTS-A proposal are outlined. Some of the aspects of the earthquake network and the results obtained from it as well as some promising experiments in computerized record processing are discussed.

  12. Remote sensing of volcanos and volcanic terrains

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  13. Three-dimensional P-wave velocity structure of Bandai volcano in northeastern Japan inferred from active seismic survey

    NASA Astrophysics Data System (ADS)

    Yamawaki, Teruo; Tanaka, Satoru; Ueki, Sadato; Hamaguchi, Hiroyuki; Nakamichi, Haruhisa; Nishimura, Takeshi; Oikawa, Jun; Tsutsui, Tomoki; Nishi, Kiyoshi; Shimizu, Hiroshi; Yamaguchi, Sosuke; Miyamachi, Hiroki; Yamasato, Hitoshi; Hayashi, Yutaka

    2004-12-01

    The three-dimensional P-wave velocity structure of the Bandai volcano has been revealed by tomographic inversion using approximately 2200 travel-time data collected during an active seismic survey comprising 298 temporary seismic stations and eight artificial shots. The key result of this study is the delineation of a high-velocity anomaly (Vp>4.6 km/s at sea-level) immediately below the summit peak. This feature extends to depths of 1-2 km below sea-level. The near-surface horizontal position of the high-velocity anomaly coincides well with that of a positive Bouguer gravity anomaly. Geological data demonstrate that sector collapses have occurred in all directions from the summit and that the summit crater has been repeatedly refilled with magmatic material. These observations suggest that the high-velocity region revealed in this study is a manifestation of an almost-solidified magmatic plumbing system. We have also noted that a near-surface low-velocity region (Vp<3.0 km/s at sea-level) on the southern foot of the volcano corresponds to the position of volcanic sediments including ash and debris avalanche material. In addition, we have made use of the tomographic results to recompute the hypocenters of earthquake occurring during seismic swarms beneath the summit in 1988 and 2000. Relocating the earthquakes using the three-dimensional velocity model clearly indicates that they predominantly occurred on two steeply dipping planes. Low-frequency earthquakes observed during the swarms in 2000 occurred in the seismic gap between the two clusters. The hypocentral regions of the seismic swarms and the low-frequency earthquakes are close to the higher-velocity zone beneath the volcano's summit. These observations suggest that the recent seismic activity beneath the summit is likely associated with thermal energy being released within the solidifying magmatic plumbing system.

  14. Activity of Nyiragongo and Nyamulagira Volcanoes (Dem. Rep. of Congo) Revealed Using Geological, Geophysical and InSAR data

    NASA Astrophysics Data System (ADS)

    Wauthier, C.; Cayol, V.; Hooper, A.; Kervyn, F.; Marinkovic, P.; D'Oreye, N.; Poland, M. P.

    2010-12-01

    Ground-based monitoring of active volcanoes in Africa can be problematic due to political instabilities, safety issues and poor accessibility. Remote-sensing techniques such as Differential Interferometric Synthetic Aperture Radar (DInSAR, more commonly InSAR), are therefore very useful and provide robust observational tools for natural hazard assessment, regardless of local conditions. Nyiragongo and Nyamulagira volcanoes (which experienced nine eruptions from December 1996 to January 2010) are located in the western branch of the East African Rift (Virunga Volcanic Province, North Kivu, Dem. Rep. of Congo). InSAR has recorded ground displacements related to most of the tectonic and volcanic events that have occurred since 1996 using SAR images from the JERS, ERS-1/2, ENVISAT, RADARSAT-1, RADARSAT-2 and ALOS satellites. This database provides excellent spatial and temporal resolution of deformation, leading to insights into tectonic and volcanic processes. Loss of coherence within the SAR signal due to rapid-changing equatorial vegetation hampers the use of InSAR as a volcano-tectonic monitoring tool. We partially overcome this limitation using 1) a large number of SAR images, including about 150 ENVISAT and more than 100 RADARSAT-1 images, 2) short repeat times of 24 and 35 days for RADARSAT-1 and ENVISAT, respectively, and 3) satellites with longer wavelengths, such as JERS and ALOS. Using a large dataset combining short revisit time SAR images significantly increases the chances of producing interferograms with good coherence. A longer wavelength radar signal better penetrates vegetation cover, also increasing coherence. Furthermore, useful data were retrieved in low-coherence areas by applying the “StaMPS” (Stanford Method for Persistent Scatterers) method, which combines a small baseline and persistent scatterers approach, to our largest SAR datasets. Using several look angles from both ascending and descending orbital tracks, we were able to characterize

  15. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  16. Gravity anomalies of the active mud diapirs off southwest Taiwan

    NASA Astrophysics Data System (ADS)

    Doo, Wen-Bin; Hsu, Shu-Kun; Lo, Chung-Liang; Chen, Song-Chuen; Tsai, Ching-Hui; Lin, Jing-Yi; Huang, Yuan-Ping; Huang, Yin-Sheng; Chiu, Shye-Donq; Ma, Yu-Fang

    2015-12-01

    Overpressure and buoyant effect of underlying sediments are generally used to account for the upward motion or formation of submarine mud volcanoes and mud diapirs. In this study, we process and interpret the gravity anomalies associated with the active mud diapirs off SW Taiwan. Geologically, the mud diapirs are just formed and are still very active, thus we can better understand the initial process of the mud diapirs formation through the gravity analysis. Our results show that the density contrasts of the submarine mud diapirs with respect to the surroundings are generally positive. Because the study area is in a tectonically compressive regime and the gas plume venting from the submarine mud volcanoes is very active, we thus infer that mechanically the mud diapirs off SW Taiwan have been formed mainly due to the tectonic compression on the underlying sediments of high pore-fluid pressure, instead of the buoyancy of the buried sediments. The overpressured sediments and fluid are compressed and pushed upwards to pierce the overlying sediments and form the more compacted mud diapirs. The relatively denser material of the mud diapirs probably constrains the flowing courses of the submarine canyons off SW Taiwan, especially for the upper reaches of the Kaoping and Fangliao submarine canyons.

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

    USGS Publications Warehouse

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

    2008-01-01

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

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

    PubMed Central

    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

  19. Simultaneous explosive and effusive activity at Chaitén volcano, Chile

    NASA Astrophysics Data System (ADS)

    Castro, J. M.; Lowenstern, J. B.; Pallister, J. S.; Eichelberger, J. C.

    2010-12-01

    The 2008 eruption of Chaitén Volcano began with Plinian to sub-Plinian activity that fluctuated in intensity over a period of weeks and then gave way to several months of rapid and voluminous lava extrusion. The change from fully explosive to fully effusive behaviour was not sudden, but rather, characterized by simultaneous effusive and sustained pyroclastic fountaining from what appeared to be a single vent, or perhaps two closely spaced smaller vents. As there appears to be no evidence for two separate magma batches with correspondingly different volatile budgets, the contemporaneous and juxtaposed explosive and effusive activity must reflect a divergence of magma flow properties, changing shallow vent characteristics, and/or degassing mechanism(s) in the conduit. We explore this enigmatic episode through field observations and thorough characterization of eruptive products spanning the full eruptive sequence, paying particular attention to: 1) the groundmass textures of tuffisite-bearing obsidian bombs, welded breccias, and pumice and obsidian pyroclasts, and 2) a thorough H2O-inventory of pyroclasts and lava samples determined with high-resolution synchrotron-FTIR. In proximal vent sites, there is a preponderance of obsidian breccia, welded pumice agglomerate, and tuffisite-veined obsidian bombs. The brecciated materials likely record conduit erosion, transient vent backfilling and partial welding, followed by re-ejection of juvenile material during the early energetic explosive phase. The presence of incipiently welded, ash-filled fractures (tuffisites) may evidence shear-induced fracturing of viscous rhyolite, followed by degassing and fluidization of ash within the fractures, thereby providing an efficient outgassing mechanism. Petrological experiments suggest the Chaitén magma initially had on the order of ~4 wt.% H2O. Rhyolite glass inclusions (n=6) are much drier, having maximum total water of 2.4 wt.%. Many inclusions, however, contain separate vapor

  20. Volcano Hazards Assessment for Medicine Lake Volcano, Northern California

    USGS Publications Warehouse

    Donnelly-Nolan, Julie M.; Nathenson, Manuel; Champion, Duane E.; Ramsey, David W.; Lowenstern, Jacob B.; Ewert, John W.

    2007-01-01

    Medicine Lake volcano (MLV) is a very large shield-shaped volcano located in northern California where it forms part of the southern Cascade Range of volcanoes. It has erupted hundreds of times during its half-million-year history, including nine times during the past 5,200 years, most recently 950 years ago. This record represents one of the highest eruptive frequencies among Cascade volcanoes and includes a wide variety of different types of lava flows and at least two explosive eruptions that produced widespread fallout. Compared to those of a typical Cascade stratovolcano, eruptive vents at MLV are widely distributed, extending 55 km north-south and 40 km east-west. The total area covered by MLV lavas is >2,000 km2, about 10 times the area of Mount St. Helens, Washington. Judging from its long eruptive history and its frequent eruptions in recent geologic time, MLV will erupt again. Although the probability of an eruption is very small in the next year (one chance in 3,600), the consequences of some types of possible eruptions could be severe. Furthermore, the documented episodic behavior of the volcano indicates that once it becomes active, the volcano could continue to erupt for decades, or even erupt intermittently for centuries, and very likely from multiple vents scattered across the edifice. Owing to its frequent eruptions, explosive nature, and proximity to regional infrastructure, MLV has been designated a 'high threat volcano' by the U.S. Geological Survey (USGS) National Volcano Early Warning System assessment. Volcanic eruptions are typically preceded by seismic activity, but with only two seismometers located high on the volcano and no other USGS monitoring equipment in place, MLV is at present among the most poorly monitored Cascade volcanoes.

  1. Geology and petrology of Mahukona Volcano, Hawaii

    USGS Publications Warehouse

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

    1991-01-01

    The submarine Mahukona Volcano, west of the island of Hawaii, is located on the Loa loci line between Kahoolawe and Hualalai Volcanoes. The west rift zone ridge of the volcano extends across a drowned coral reef at about-1150 m and a major slope break at about-1340 m, both of which represent former shoreines. The summit of the volcano apparently reached to about 250 m above sea level (now at-1100 m depth) did was surmounted by a roughly circular caldera. A econd rift zone probably extended toward the east or sutheast, but is completely covered by younger lavas from the adjacent subaerial volcanoes. Samples were vecovered from nine dredges and four submersible lives. Using subsidence rates and the compositions of flows which drape the dated shoreline terraces, we infer that the voluminous phase of tholeiitic shield growth ended about 470 ka, but tholeiitic eruptions continued until at least 435 ka. Basalt, transitional between tholeiitic and alkalic basalt, erupted at the end of tholeiitic volcanism, but no postshield-alkalic stage volcanism occurred. The summit of the volcano apparently subcided below sea level between 435 and 365 ka. The tholeiitic lavas recovered are compositionally diverse. ?? 1991 Springer-Verlag.

  2. Composition, geometry, and emplacement dynamics of a large volcanic island landslide offshore Martinique: From volcano flank-collapse to seafloor sediment failure?

    NASA Astrophysics Data System (ADS)

    Brunet, Morgane; Le Friant, Anne; Boudon, Georges; Lafuerza, Sara; Talling, Peter; Hornbach, Matthew; Ishizuka, Osamu; Lebas, Elodie; Guyard, Hervé

    2016-03-01

    Landslides are common features in the vicinity of volcanic islands. In this contribution, we investigate landslides emplacement and dynamics around the volcanic island of Martinique based on the first scientific drilling of such deposits. The evolution of the active Montagne Pelée volcano on this island has been marked by three major flank-collapses that removed much of the western flank of the volcano. Subaerial collapse volumes vary from 2 to 25 km3 and debris avalanches flowed into the Grenada Basin. High-resolution seismic data (AGUADOMAR-1999, CARAVAL-2002, and GWADASEIS-2009) is combined with new drill cores that penetrate up to 430 m through the three submarine landslide deposits previously associated to the aerial flank-collapses (Site U1399, Site U1400, Site U1401, IODP Expedition 340, Joides Resolution, March-April 2012). This combined geophysical and core data provide an improved understanding of landslide processes offshore a volcanic island. The integrated analysis shows a large submarine landslide deposit, without debris avalanche deposits coming from the volcano, comprising up to 300 km3 of remobilized seafloor sediment that extends for 70 km away from the coast and covers an area of 2100 km2. Our new data suggest that the aerial debris avalanche deposit enter the sea but stop at the base of submarine flank. We propose a new model dealing with seafloor sediment failures and landslide propagation mechanisms, triggered by volcanic flank-collapse events affecting Montagne Pelée volcano. Newly recognized landslide deposits occur deeper in the stratigraphy, suggesting the recurrence of large-scale mass-wasting processes offshore the island and thus, the necessity to better assess the associated tsunami hazards in the region.

  3. Mud Volcanoes Formation And Occurrence

    NASA Astrophysics Data System (ADS)

    Guliyev, I. S.

    2007-12-01

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

  4. Syrian Volcano

    NASA Technical Reports Server (NTRS)

    2006-01-01

    23 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small volcano in the Syria Planum region of Mars. Today, the lava flows that compose this small volcano are nearly hidden by a mantle of rough-textured, perhaps somewhat cemented, dust. The light-toned streaks that cross the scene were formed by passing dust devils, a common occurrence in Syria.

    Location near: 13.0oS, 102.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  5. First 3D thermal mapping of an active volcano using an advanced photogrammetric method

    NASA Astrophysics Data System (ADS)

    Antoine, Raphael; Baratoux, David; Lacogne, Julien; Lopez, Teodolina; Fauchard, Cyrille; Bretar, Frédéric; Arab-Sedze, Mélanie; Staudacher, Thomas; Jacquemoud, Stéphane; Pierrot-Deseilligny, Marc

    2014-05-01

    to extract 3D informations from thermal images taken from different positions. This paper presents the first 3D thermal map of an active volcano (Piton de la Fournaise, La Réunion Island) directly generated from 70 thermal images (so-called "stereothermogrammetric" DEM). The data were obtained above Dolomieu caldera by helicopter just before sunrise, during a clear weather in 2008. They were obtained before the eruptive events occurring within the Dolomieu caldera. We used a 28 mm focal FLIR Thermacam PM695 lent by the Piton de la Fournaise Observatory. The thermal images were acquired automatically every 30 seconds with the helicopter flying around the caldera at low altitude (less than 100 m height above the caldera). This survey led to the acquisition of images with a ground pixel size in the range of 1-3 m. A particular attention has been brought to the obtaining of a high overlap percentage (80 percents) for the localization of the maximum tie points on the image. Finally, the acquisition of 70 images allowed the generation of a 3D thermal model of the caldera containing more than 500000 points. i.e. 1 point each 2 m², considering a surface of 106 m² for the Dolomieu caldera. This model is then compared with a DEM recently obtained with the LIDAR method after the eruptive events occurring within Dolomieu. The comparison of these independent methods leads to the validation of the stereothermogrammetric method. It allows the quantification of the thickness of the lava flows within the Dolomieu collapse in 2008 and 2009, i.e. approximately 80 meters, as estimated by previous studies from field observations.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  7. Methane anomalies in seawater above the Loihi submarine summit area, Hawaii

    SciTech Connect

    Gamo, Toshitaka; Ishibashi, Junichiro; Sakai, Hitoshi ); Tilbrook, B. )

    1987-10-01

    Hydrothermal activity above Loihi submarine volcano was characterized by water column distributions of methane, pH and helium-3. It was found that the southern Loihi summit is almost covered with hydrothermal plumes, which have anomalously high concentrations of methane (maximum: 569 {times} 10{sup {minus}6} cm{sup 3} kg{sup {minus}}1) accompanied by high concentrations of helium-3 and low pH values (minimum: 7.18). The plumes consist of two layers: a shallow plume (about 200 m above the summit) and a deep plume (about 100 m above the summit), probably derived from different hydrothermal vents. The shallow and deep plumes showed different CH{sub 4}/{sup 3}He and CH{sub 4}/pH ratios with the same {sup 3}He/pH ratio, which implies that methane concentrations differ between the hydrothermal end members for the two plumes. The variation of methane between the end members is suggested to result from inter-vent inhomogeneity of bacterial activities that consume or produce methane within the vents. Comparison of the CH{sub 4}/{sup 3}He ratios of the two plumes with the previous data for Loihi and other submarine hydrothermal areas confirms that the Loihi hotspot has one to two orders of magnitude smaller CH{sub 4}/{sup 3}He value than those of the East Pacific Rise and the Galapagos spreading centers.

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

    PubMed

    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.

  9. Transient Changes in Bacterioplankton Communities Induced by the Submarine Volcanic Eruption of El Hierro (Canary Islands)

    PubMed Central

    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

  10. Preliminary volcano-hazard assessment for Great Sitkin Volcano, Alaska

    USGS Publications Warehouse

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

    2003-01-01

    Great Sitkin Volcano is a composite andesitic stratovolcano on Great Sitkin Island (51°05’ N latitude, 176°25’ W longitude), a small (14 x 16 km), circular volcanic island in the western Aleutian Islands of Alaska. Great Sitkin Island is located about 35 kilometers northeast of the community of Adak on Adak Island and 130 kilometers west of the community of Atka on Atka Island. Great Sitkin Volcano is an active volcano and has erupted at least eight times in the past 250 years (Miller and others, 1998). The most recent eruption in 1974 caused minor ash fall on the flanks of the volcano and resulted in the emplacement of a lava dome in the summit crater. The summit of the composite cone of Great Sitkin Volcano is 1,740 meters above sea level. The active crater is somewhat lower than the summit, and the highest point along its rim is about 1,460 meters above sea level. The crater is about 1,000 meters in diameter and is almost entirely filled by a lava dome emplaced in 1974. An area of active fumaroles, hot springs, and bubbling hot mud is present on the south flank of the volcano at the head of Big Fox Creek (see the map), and smaller ephemeral fumaroles and steam vents are present in the crater and around the crater rim. The flanking slopes of the volcano are gradual to steep and consist of variously weathered and vegetated blocky lava flows that formed during Pleistocene and Holocene eruptions. The modern edifice occupies a caldera structure that truncates an older sequence of lava flows and minor pyroclastic rocks on the east side of the volcano. The eastern sector of the volcano includes the remains of an ancestral volcano that was partially destroyed by a northwest-directed flank collapse. In winter, Great Sitkin Volcano is typically completely snow covered. Should explosive pyroclastic eruptions occur at this time, the snow would be a source of water for volcanic mudflows or lahars. In summer, much of the snowpack melts, leaving only a patchy

  11. Volcano Hazards Program

    USGS Publications Warehouse

    Venezky, Dina Y.; Myers, Bobbie; Driedger, Carolyn

    2008-01-01

    Diagram of common volcano hazards. The U.S. Geological Survey Volcano Hazards Program (VHP) monitors unrest and eruptions at U.S. volcanoes, assesses potential hazards, responds to volcanic crises, and conducts research on how volcanoes work. When conditions change at a monitored volcano, the VHP issues public advisories and warnings to alert emergency-management authorities and the public. See http://volcanoes.usgs.gov/ to learn more about volcanoes and find out what's happening now.

  12. Chikurachki Volcano

    Atmospheric Science Data Center

    2013-04-16

    ... southeast. The darker areas of the plume typically indicate volcanic ash, while the white portions of the plume indicate entrained water droplets and ice. According to the Kamchatkan Volcanic Eruptions Response Team (KVERT), the temperature of the plume near the volcano ...

  13. Eruptive activity of enigmatic medium-sized volcanoes in the Michoacán-Guanajuato Volcanic Field (MGVF), Central Mexico: The case of El Metate

    NASA Astrophysics Data System (ADS)

    Chevrel, M.; Siebe, C.; Guilbaud, M. N.

    2014-12-01

    The MGVF has a total area of ca. 40,000 km2 and is well known for being the host of the only two monogenetic volcanoes in Mexico that were born in historical times: Jorullo (1759-1774) and Paricutin (1943-1952). Another particularity of the MGVF is its high number of eruptive vents with over 1000 small monogenetic cones and associated lava flows (average vol. of 0.021 km3) and ca. 400 medium-sized volcanoes (average vol. from 0.5 to 50 km3). Most of these medium-sized volcanoes may be characterized as shields that were produced dominantly by effusive activity as opposed to the small cones formed also by explosive phases of activity. The products of the small cones range from olivine basalts to andesites whereas the medium-sized volcanoes are restricted to a smaller compositional range in the andesitic domain. Although the medium-sized volcanoes are more sparsely distributed in time and space and less abundant than the small cones, the risks associated with renewal of this type of activity should not be neglected. This study focuses on El Metate which is probably the youngest shield of the MGVF (< 3,700 y. BP). Unlike a typical shield volcano composed of a succession of thin fluid basaltic flows, El Metate consists of well-preserved >60 m thick andesite flows distributed radially around a summit dome. Detailed mapping and sampling allowed us to reconstruct its eruptive activity and the time sequence of lava flow emplacement. We have identified 13 individual lava flows with lengths ranging between 3 and 15 km covering 103 km2 and average thicknesses between 60 and 150 m. Individual volumes range between 0.5 and 3.5 km3 for a total of 11 to 15 km3. Estimates of flow emplacement parameters indicate maximum average effusion rates ranging between 15 and 100 m3.s-1 and a cumulative duration from 15 to 30 years. Such a short emplacement time is comparable to the historical monogenetic eruption of nearby Paricutin volcano (9 years) but the erupted volume of lava is

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

    NASA Astrophysics Data System (ADS)

    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

  15. Catalogue of Icelandic Volcanoes

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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