Sample records for volcano aleutian islands

  1. Kanaga Volcano, Aleutian Islands, Alaska

    NSDL National Science Digital Library

    These images of the Kanaga Volcano show the symmetrical cone which is characteristic of stratovolcanoes. It is also possible to see how the current volcanic edifice has grown inside an older caldera, the remains of ancient Mount Kanaton. References and links to related sites are included.

  2. Preliminary Geology of Gareloi Volcano, Western Aleutian Islands (Alaska)

    NASA Astrophysics Data System (ADS)

    Browne, B. L.; Coombs, M.; Larsen, J.

    2004-12-01

    Gareloi Island consists of Gareloi volcano (1573 m elevation), and is located nearly 2000 km west of Anchorage and 120 km west of Adak in the western Aleutian (Andreanof) Islands. A geologic mapping operation was combined with the installation of a seismic monitoring network in September of 2003 by the Alaska Volcano Observatory. This work provided the first direct observations of Gareloi volcano since Robert Coats' four-day visit in 1945. Gareloi volcano is a stratovolcano 10 km by 8 km in diameter at its base with two summit craters separated by a narrow saddle. The southern crater is a 300-m-wide amphitheater formed by the partial collapse of its southern crater wall, and contains several active fumaroles. The northern crater is enclosed, although the intra-crater eruptive stratigraphy is abruptly interrupted by near-vertical local unconformities on the northwest wall, suggesting the occurrence of a sector collapse sometime in the past. Gareloi volcano is principally composed of intercalated trachytic lava flows, ranging from 0.5 m to more than 10 m in thickness. Two prominent valleys composed of thick lava flow packages on the SW flank are clearly U-shaped, suggesting that the oldest sequence of lava flows is of at least late Pleistocene age. Lavas erupted during the Pleistocene and Holocene range from basaltic trachyandesite to basaltic andesite in composition and contain plagioclase and clinopyroxene, with minor olivine, and rare hornblende. An explosive eruption in 1929 formed a SSE trending fissure of thirteen aligned craters, ranging from 80 to 1600 m in diameter. These craters extend from sea level up to the amphitheater of the southern crater (1160 m). Fall deposits from the 1929 eruption are interbedded with thin, laterally discontinuous pyroclastic flow deposits that are mainly limited to the island's southeastern flanks. Despite an abrupt change in color from light beige pumice clasts at the base of the 1929 fall deposit to black scoria at the top, the unit is homogeneous trachyandesite. Following the explosive phase of the eruption, 4 blocky trachyandesite lava flows emerged from craters below 600 m asl. All 1929 eruptive products contain plagioclase and clinopyroxene with scarce olivine. An effusive eruption during the 1980's from the center of the south crater amphitheater produced an elaborate blocky lava flow that extends 800 m in elevation down the SE flank. This lava flow is basaltic trachyandesite, and contains abundant coarsely sieved plagioclase phenocrysts with minor clinopyroxene and olivine. The majority of Gareloi lavas contain anomalously high concentrations of K, Na, and Rb and low concentrations of Mg compared to reported findings from other Aleutian lavas, including those of the western portion of the arc. This suggests that Gareloi magmas may be unique with respect to their source region and possibly storage conditions compared to other Aleutian volcanoes.

  3. The 2008 Eruption of Kasatochi Volcano, Central Aleutian Islands, Alaska: Reconnaissance Observations and Preliminary Physical Volcanology

    Microsoft Academic Search

    C. F. Waythomas; D. J. Schneider; S. G. Prejean

    2008-01-01

    The August 7, 2008 eruption of Kasatochi volcano was the first documented historical eruption of this small (3 x 3 km) island volcano with a 1 km2 lake filled crater in the central Aleutian Islands of Alaska. Reports of previous Kasatochi eruptions are unconfirmed and lacking in detail and little is known about the eruptive history. Three explosively-generated ash plumes

  4. August 2008 eruption of Kasatochi volcano, Aleutian Islands, Alaska-resetting an Island Landscape

    USGS Publications Warehouse

    Scott, W.E.; Nye, C.J.; Waythomas, C.F.; Neal, C.A.

    2010-01-01

    Kasatochi Island, the subaerial portion of a small volcano in the western Aleutian volcanic arc, erupted on 7-8 August 2008. Pyroclastic flows and surges swept the island repeatedly and buried most of it and the near-shore zone in decimeters to tens of meters of deposits. Several key seabird rookeries in taluses were rendered useless. The eruption lasted for about 24 hours and included two initial explosive pulses and pauses over a 6-hr period that produced ash-poor eruption clouds, a 10-hr period of continuous ash-rich emissions initiated by an explosive pulse and punctuated by two others, and a final 8-hr period of waning ash emissions. The deposits of the eruption include a basal muddy tephra that probably reflects initial eruptions through the shallow crater lake, a sequence of pumiceous and lithic-rich pyroclastic deposits produced by flow, surge, and fall processes during a period of energetic explosive eruption, and a fine-grained upper mantle of pyroclastic-fall and -surge deposits that probably reflects the waning eruptive stage as lake and ground water again gained access to the erupting magma. An eruption with similar impact on the island's environment had not occurred for at least several centuries. Since the 2008 eruption, the volcano has remained quiet other than emission of volcanic gases. Erosion and deposition are rapidly altering slopes and beaches. ?? 2010 Regents of the University of Colorado.

  5. Geology and 40Ar/39Ar Geochronology of Akutan Volcano, Eastern Aleutian Islands

    NASA Astrophysics Data System (ADS)

    Coombs, M. L.; Jicha, B. R.

    2013-12-01

    40Ar/39Ar dating and new whole-rock geochemical analyses are used to establish an eruptive chronology for Akutan volcano, Akutan Island, in the eastern Aleutian island arc. Akutan Island (166° W, 54.1° N) is the site of long-lived volcanism and the entire island comprises volcanic rocks as old as 3.3 Ma (Richter et al., 1998, USGS Open-File 98-135). Our current focus is on the 225 km2 western half of the island, which is home to the Holocene active cone, Holocene to latest Pleistocene satellite vents, and underlying middle Pleistocene volcanic basement rocks. Eruptive products span the tholeiitic-calc-alkaline boundary, are medium-K, and range from basalt to dacite. Furnace incremental heating experiments on groundmass separates of 38 samples resulted in 29 40Ar/39Ar ages. The remainder did not yield radiogenic 40Ar contents and are likely Holocene in age. The oldest ages (1251×10 and 1385×12 ka) are from a wedge of flat-lying dissected lavas north of the Holocene cone; these likely represent the upper part of the volcanic basement that underlies the entire island. Above a major unconformity lie basaltic andesite to dacite lavas that range from 765× 4 to 522×8 ka. The eroded remnants of the source volcano for these flows appears to crop out as a series of variably hydrothermally altered breccias and domes 5 km east-northeast of the current summit. A 625 m-tall eroded basaltic center, Lava Peak, sits 6 km northwest of the summit; its deeply incised western flank exposes lava flows and a plug. Two flows are dated at 598×16 and 602×15 ka. A high ridge 1.5 km south of the summit is made of oxidized, mostly andesitic lavas 284-249 ka old; these are presumably the remnants of an eruptive center located near the current cone. Flat Top Peak, 3.5 km southwest of the summit, produced almost exclusively basalts and six dated lavas range from 155×8 to 98×18 ka. Lavas from Flat Top (1065 m asl) are deeply eroded suggesting extensive ice cover during marine isotope stages 4-2. Cascade Bight, an eruptive center 4.5 km southeast of the caldera, has apparently been active in the Holocene as two experiments on basaltic andesite lavas yielded no radiogenic argon. Holocene lavas are also exposed along the upper walls of the ~1,600 yr old summit caldera (Waythomas, 1999, Bull Volc, v. 61, p. 141-161), including dissected 1296 m-tall Akutan Peak (the current summit), as well as low on the north and west flanks of the Akutan edifice. Holocene lavas, including those from Cascade Bight as well as Lava Point satellite vent on the NW coast, all fall along a single tholeiitic, basalt-to-dacite evolutionary trend that has lower K than Pleistocene lavas. Our results show that the focus of volcanism has shifted within the western half of Akutan Island over the last ~600 ka, and that on occasion multiple volcanic centers have been active over the same time period, including within the Holocene.

  6. What controls earthquakes at Aleutian arc volcanoes?

    NASA Astrophysics Data System (ADS)

    Buurman, H.; West, M. E.; Cameron, C.

    2012-12-01

    Alaska has around 100 Holocene active volcanoes spread over 3000 km of the Aleutian arc, from Mount Wrangell in southcentral Alaska to Buldir Island in the western Aleutian islands. The range in volcanic styles across the arc is as great as the distance that it spans, and so too is the accompanying volcano seismicity. This study examines whether there are systematic influences on volcano seismicity across the Aleutian arc that can account for distinctive patterns in earthquake behaviour, such as the paucity of deep (>20 km depth) volcanic earthquakes in the Cook Inlet region compared to volcanic earthquakes at the westernmost portion of the Alaska Peninsula. We investigate whether physical factors such as volcano size, geographic location relative to the subduction zone, the regional setting - including the type of crust and the distance between the vent and the ocean - and the local angle and rate of subduction affect volcano seismicity. We use continuous seismic data recorded over a 10-year period at 47 volcanoes to characterise patterns in seismicity. Our analyses consider the number and locations of hypocenters, waveform characteristics such as frequency content and magnitude, and the frequency and style of volcanic unrest during the study period.

  7. Hazard communication by the Alaska Volcano Observatory Concerning the 2008 Eruptions of Okmok and Kasatochi Volcanoes, Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Adleman, J. N.; Cameron, C. E.; Neal, T. A.; Shipman, J. S.

    2008-12-01

    The significant explosive eruptions of Okmok and Kasatochi volcanoes in 2008 tested the hazard communication systems at the Alaska Volcano Observatory (AVO) including a rigorous test of the new format for written notices of volcanic activity. AVO's Anchorage-based Operations facility (Ops) at the USGS Alaska Science Center serves as the hub of AVO's eruption response. From July 12 through August 28, 2008 Ops was staffed around the clock (24/7). Among other duties, Ops staff engaged in communicating with the public, media, and other responding federal and state agencies and issued Volcanic Activity Notices (VAN) and Volcano Observatory Notifications for Aviation (VONA), recently established and standardized products to announce eruptions, significant activity, and alert level and color code changes. In addition to routine phone communications with local, national and international media, on July 22, AVO held a local press conference in Ops to share observations and distribute video footage collected by AVO staff on board a U.S. Coast Guard flight over Okmok. On July 27, AVO staff gave a public presentation on the Okmok eruption in Unalaska, AK, 65 miles northeast of Okmok volcano and also spoke with local public safety and industry officials, observers and volunteer ash collectors. AVO's activity statements, photographs, and selected data streams were posted in near real time on the AVO public website. Over the six-week 24/7 period, AVO staff logged and answered approximately 300 phone calls in Ops and approximately 120 emails to the webmaster. Roughly half the logged calls were received from interagency cooperators including NOAA National Weather Service's Alaska Aviation Weather Unit and the Center Weather Service Unit, both in Anchorage. A significant number of the public contacts were from mariners reporting near real-time observations and photos of both eruptions, as well as the eruption of nearby Cleveland Volcano on July 21. As during the 2006 eruption of Augustine volcano in Cook Inlet, Alaska, the number of calls to Ops, emails to the webmaster, and the amount of data served via the AVO website greatly increased during elevated volcanic activity designated by the USGS aviation color code and volcano alert level. Lessons learned include, Ops staffing requirements during periods of high call volume, the need for ash fall hazard information in multiple languages, and the value of real-time observations of remote Aleutian eruptions made by local mariners. An important theme of public inquiries concerned the amount and potential climate impacts of the significant sulfur dioxide gas and ash plumes emitted by Okmok and Kasatochi, including specific questions on the amount of sulfur dioxide discharged during each eruption. The significant plumes produced at the onset of the Okmok and Kasatochi eruptions also had lengthy national and international aviation impacts and yet-to-be resolved hemispherical or possible global, climactic effects.

  8. Pleistocene-Recent Growth and Collapse of an Island arc Volcano: Precise 40Ar\\/39Ar Dating of Seguam Island, Central Aleutian arc, Alaska

    Microsoft Academic Search

    B. R. Jicha; B. Singer

    2003-01-01

    Quantifying the long term growth of arc volcanoes can be done through geologic mapping supported by K-Ar or 40Ar\\/39Ar age determinations, and is essential to connect rates of geochemical and petrologic processes to a volcano's eruptive history. Yet, few island arcs have benefitted from K-Ar or 40Ar\\/39Ar dating. No 40Ar\\/39Ar data is published from the 24 active volcanoes in the

  9. Perspective View of Umnak Island, Aleutian Islands, Alaska (#1)

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image is a perspective view of Umnak Island, one of Alaska's Aleutian Islands. The active Okmok volcano appears in the center of the island.

    The image was created by draping a Landsat 7 Thematic Mapper image over a digital elevation mosaic derived from Airsar data.

    This work was conducted as part of a NASA-funded Alaska Digital Elevation Model Project at the Alaska Synthetic Aperture Radar Facility (ASF) at the University of Alaska Geophysical Institute in Fairbanks, Alaska.

    Airsar collected the Alaska data as part of its PacRim 2000 Mission, which took the instrument to French Polynesia, American and Western Samoa, Fiji, New Zealand, Australia, New Guinea, Indonesia, Malaysia, Cambodia, Philippines, Taiwan, South Korea, Japan, Northern Marianas, Guam, Palau, Hawaii and Alaska. Airsar, part of NASA's Airborne Science Program, is managed for NASA's Earth Science Enterprise by JPL. JPL is a division of the California Institute of Technology in Pasadena.

  10. Perspective View of Umnak Island, Aleutian Islands, Alaska (#2)

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image is a perspective view of Umnak Island, one of Alaska's Aleutian Islands. The active Okmok volcano appears in the center of the island.

    The image was created by draping a Landsat 7 Thematic Mapper image over a digital elevation mosaic derived from Airsar data.

    This work was conducted as part of a NASA-funded Alaska Digital Elevation Model Project at the Alaska Synthetic Aperture Radar Facility (ASF) at the University of Alaska Geophysical Institute in Fairbanks, Alaska.

    Airsar collected the Alaska data as part of its PacRim 2000 Mission, which took the instrument to French Polynesia, American and Western Samoa, Fiji, New Zealand, Australia, New Guinea, Indonesia, Malaysia, Cambodia, Philippines, Taiwan, South Korea, Japan, Northern Marianas, Guam, Palau, Hawaii and Alaska. Airsar, part of NASA's Airborne Science Program, is managed for NASA's Earth Science Enterprise by JPL. JPL is a division of the California Institute of Technology in Pasadena.

  11. Surface Deformation Caused by a Shallow Magmatic Source at Okmok Volcano, Aleutian Arc

    Microsoft Academic Search

    Y. Miyagi; J. T. Freymueller; F. Kimata; T. Sato; D. Mann; M. Kasahara

    2001-01-01

    Okmok Volcano, located on Umnak Island in the eastern Aleutian arc, last erupted in 1997. Okmok consists of a 10 km wide caldera with several cones located inside. Significant surface deformation before, during and after the eruption has been measured using InSAR. However, the area of coherent data has been limited to the northern part of the caldera, with some

  12. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...and NOAA chart 530 (San Diego to Aleutian Islands...District. The area south of...and NOAA chart 530 (San Diego to Aleutian Islands...District. The area south of...and NOAA chart 530 (San Diego to Aleutian...

  13. A photographic guide to some vascular plants of Kiska Island, Aleutian Islands, Alaska

    E-print Network

    Jones, Ian L.

    A photographic guide to some vascular plants of Kiska Island, Aleutian Islands, Alaska Geum Rossi, lush meadows, wetlands, and rocky tundra. The island's geology varies, with southern parts old (mid. With respect to plant biogeography, Kiska lies in the central Aleutian zone of depressed diversity, lacking

  14. Criconematina (nematoda: tylenchida) from the Aleutian Islands

    SciTech Connect

    Bernard, E.C.

    1982-01-01

    A new genus (Cerchnotocriconema) and three new species (C. psephinum, Hemicycliophora anchitkaensis, and Paratylenchus amundseni) are described from Adak and Amchitka Islands in the Aleutian chain. The new genus differs from all other criconematid genera in having irregular, convex sculpturing consisting of small, oval plates on the anterior and posterior regions of each annule, with the mid-annular region minutely punctate or dentate. H. amchitkaensis n. sp. resembles H. sinilis Thorne and H. zuckermani Brzeski, but has only one head annule, instead of two. P. amundseni n. sp., which has a stylet 17 to 19 ..mu..m long, is similar to P. tatea Wu and Townsend and P. labiosus Anderson and Kimpinski, but differs by the presence of males and the possession of conoid-truncate lip region, functional spermatheca, and long male tail (c = 8.5 to 9.5). Seriespinula seymouri Wu (Mehta and Raski), Nothocriconema longulum (Gunhold) De Grisse and Loof, and Macroposthonia xenoplax (Raski) De Grisse and Loof are also reported from the islands.

  15. InSAR Imaging of Volcanic Deformation Over Aleutian Islands

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Dzurisin, D.; Wicks, C.; Power, J.; Kwoun, O.; Rykhus, R.

    2005-12-01

    Interferometric synthetic aperture radar (InSAR) is capable of measuring ground-surface deformation with centimeter to subcentimeter precision and spatial resolution of tens-of-meters over relatively large regions under all weather conditions. The spatial distribution of surface deformation data, derived from InSAR images, enables the exploration of detailed mechanical models to enhance the study of volcanic and tectonic processes. This paper summarizes our InSAR studies of more than a dozen Alaskan volcanoes, associated with both eruptive and non-eruptive activity. These examples include the pre-eruption inflation, co-eruption deflation, and post-eruption inflation at Okmok Volcano; magmatic intrusion and the associated tectonic stress release at Akutan Volcano; progressive aseismic inflation of Westdahl Volcano; magmatic intrusion at Mount Peulik Volcano and its relation to an earthquake swarm 30 km away; magmatic intrusion associated with a small eruption at Makushin Volcano in 1995; complex patterns of transient deformation during and after the 1992-1993 eruption at Seguam Volcano; surface subsidence caused by a decrease in pore fluid pressure in an active hydrothermal system beneath Kiska Volcano; compaction of young pyroclastic flow deposits at Augustine Volcano; persistent volcano-wide subsidence at Aniakchak Volcano; and lack of expected deformation associated with recent eruptions at Shishaldin, Pavlof, Cleveland, and Korovin Volcanoes. We conclude that the deformation patterns and the associated magma supply mechanisms over Aleutian Volcanoes are diverse and vary between volcanoes. These studies demonstrate that InSAR can improve our understanding on how the Aleutian Volcanoes work and enhance our capability to predict future eruptions and associated hazards.

  16. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Shipping 1 2012-10-01 2012-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170...PROCEDURES APPLICABLE TO THE PUBLIC BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK....

  17. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Shipping 1 2013-10-01 2013-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170...PROCEDURES APPLICABLE TO THE PUBLIC BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK....

  18. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Shipping 1 2011-10-01 2011-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170...PROCEDURES APPLICABLE TO THE PUBLIC BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK....

  19. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Shipping 1 2014-10-01 2014-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170...PROCEDURES APPLICABLE TO THE PUBLIC BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK....

  20. Shaded Relief Mosaic of Umnak Island, Aleutian Islands, Alaska

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image is a shaded relief mosaic of Umnak Island in Alaska's Aleutian Islands.

    It was created with Airsar data that was geocoded and combined into this mosaic as part of a NASA-funded Alaska Digital Elevation Model Project at the Alaska Synthetic Aperture Radar Facility (ASF) at the University of Alaska Geophysical Institute in Fairbanks, Alaska.

    Airsar collected the Alaska data as part of its PacRim 2000 Mission, which took the instrument to French Polynesia, American and Western Samoa, Fiji, New Zealand, Australia, New Guinea, Indonesia, Malaysia, Cambodia, Philippines, Taiwan, South Korea, Japan, Northern Marianas, Guam, Palau, Hawaii and Alaska. Airsar, part of NASA's Airborne Science Program, is managed for NASA's Earth Science Enterprise by JPL. JPL is a division of the California Institute of Technology in Pasadena.

  1. Pacific Basin Tsunami Hazards Associated with Mass Flows in the Aleutian Islands of Alaska

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Watts, P.; Shi, F.; Kirby, J. T.

    2007-12-01

    The Aleutian Islands are a chain of volcanic islands formed by an intra-oceanic subduction zone. This area consists of a submerged chain of mountains, volcanic islands, and submarine canyons, surrounded by a low- relief continental shelf above about 1000-2000 m water depth. Part of the island chain is fragmented into a series of fault-bounded blocks, tens to hundreds of km in length, and separated from one another by distinctive fault- controlled canyons that are roughly normal to the arc axis. The canyons are geomorphically low areas between the higher relief blocks and are natural regions for the accumulation and conveyance of sediment derived from glacial and volcanic processes. The volcanic islands in the region include a number of historically active volcanoes and some possess geological evidence for large-scale sector collapse into the sea. The physical setting of the Aleutian Islands indicates that mass flows of unconsolidated debris that originate either as submarine mass flows or as subaerial debris avalanches entering the sea may be potential tsunami sources. Large scale mass-flow deposits have not been identified on the seafloor south of the Aleutian Islands, primarily because the area has never been mapped or examined at the resolution required to identify such features. Extensive submarine landslide deposits and debris flows are known on the north side of the arc and are common in similar settings elsewhere and thus they likely exist on the trench slope south of the Aleutian Islands. We suggest that tsunamigenic mass flows are a plausible geologic process in the Aleutian Islands and that the tsunamis produced by such flows may be large enough to cross the Pacific Ocean basin. To test this hypothesis we present a series of numerical simulations of submarine mass-flow initiated tsunamis from eight different source areas. We consider four submarine mass flows originating in submarine canyons and four flows that evolve from submarine landslides. The flows have lengths that range from 40-80 km, maximum thicknesses of 400-800 m, and maximum widths of 10-40 km. Although some of these hypothetical flows are large, they are not unprecedented and flows of similar dimensions are known in other continental slope settings. We calculate tsunami sources using the numerical model TOPICS and simulate wave propagation across the Pacific using a spherical Boussinesq model which is a modified version of the public domain code FUNWAVE. Our numerical simulations indicate that geologically plausible submarine mass flows originating in the North Pacific near the Aleutian Islands can indeed generate large tsunamis. These waves may be several meters in amplitude at distal locations, such as Japan, Hawaii, and along the South American coastline where they would constitute significant hazards.

  2. Subduction Controls of Hf and Nd Isotopes in Lavas of the Aleutian Island Arc

    SciTech Connect

    Yogodzinski, Gene; Vervoort, Jeffery; Brown, Shaun Tyler; Gerseny, Megan

    2010-08-29

    The Hf and Nd isotopic compositions of 71 Quaternary lavas collected from locations along the full length of the Aleutian island arc are used to constrain the sources of Aleutian magmas and to provide insight into the geochemical behavior of Nd and Hf and related elements in the Aleutian subduction-magmatic system. Isotopic compositions of Aleutian lavas fall approximately at the center of, and form a trend parallel to, the terrestrial Hf-Nd isotopic array with {var_epsilon}{sub Hf} of +12.0 to +15.5 and {var_epsilon}{sub Nd} of +6.5 to +10.5. Basalts, andesites, and dacites within volcanic centers or in nearby volcanoes generally all have similar isotopic compositions, indicating that there is little measurable effect of crustal or other lithospheric assimilation within the volcanic plumbing systems of Aleutian volcanoes. Hafnium isotopic compositions have a clear pattern of along-arc increase that is continuous from the eastern-most locations near Cold Bay to Piip Seamount in the western-most part of the arc. This pattern is interpreted to reflect a westward decrease in the subducted sediment component present in Aleutian lavas, reflecting progressively lower rates of subduction westward as well as decreasing availability of trench sediment. Binary bulk mixing models (sediment + peridotite) demonstrate that 1-2% of the Hf in Aleutian lavas is derived from subducted sediment, indicating that Hf is mobilized out of the subducted sediment with an efficiency that is similar to that of Sr, Pb and Nd. Low published solubility for Hf and Nd in aqueous subduction fluids lead us to conclude that these elements are mobilized out of the subducted component and transferred to the mantle wedge as bulk sediment or as a silicate melt. Neodymium isotopes also generally increase from east to west, but the pattern is absent in the eastern third of the arc, where the sediment flux is high and increases from east to west, due to the presence of abundant terrigenous sediment in the trench east of the Amlia Fracture Zone, which is being subducting beneath the arc at Seguam Island. Mixing trends between mantle wedge and sediment end members become flatter in Hf-Nd isotope space at locations further west along the arc, indicating that the sediment end member in the west has either higher Nd/Hf or is more radiogenic in Hf compared to Nd. This pattern is interpreted to reflect an increase in pelagic clay relative to the terrigenous subducted sedimentary component westward along the arc. Results of this study imply that Hf does not behave as a conservative element in the Aleutian subduction system, as has been proposed for some other arcs.

  3. Avian mortality associated with a volcanic gas seep at Kiska Island, Aleutian Islands, Alaska

    USGS Publications Warehouse

    Bond, Alexander L.; Evans, William C.; Jones, Ian L.

    2012-01-01

    We identified natural pits associated with avian mortality at the base of Kiska Volcano in the western Aleutian Islands, Alaska in 2007. Living, moribund, and dead birds were regularly found at low spots in a canyon between two lava flows during 2001–2006, but the phenomenon was attributed to natural trapping and starvation of fledgling seabirds (mostly Least Auklets, Aethia pusilla) at a colony site with >1 million birds present. However, 302 birds of eight species, including passerines, were found dead at the site during 2007–2010, suggesting additional factors were involved. Most carcasses showed no signs of injury and concentrations of dead birds had accumulated in a few distinctive low pits in the canyon. Gas samples from these locations showed elevated CO2 concentrations in late 2010. Analysis of carcasses indicated no evidence of blunt trauma or internal bleeding. Volcanic gases accumulating at these poorly ventilated sites may have caused the observed mortality, but are temporally variable. Most auklets breeding in the Aleutian Islands do so in recent lava flows that provide breeding habitat; our study documents a cost of this unusual habitat selection.

  4. Aleutian Pribilof Islands Wind Energy Feasibility Study

    SciTech Connect

    Bruce A. Wright

    2012-03-27

    Under this project, the Aleutian Pribilof Islands Association (APIA) conducted wind feasibility studies for Adak, False Pass, Nikolski, Sand Point and St. George. The DOE funds were also be used to continue APIA's role as project coordinator, to expand the communication network quality between all participants and with other wind interest groups in the state and to provide continued education and training opportunities for regional participants. This DOE project began 09/01/2005. We completed the economic and technical feasibility studies for Adak. These were funded by the Alaska Energy Authority. Both wind and hydro appear to be viable renewable energy options for Adak. In False Pass the wind resource is generally good but the site has high turbulence. This would require special care with turbine selection and operations. False Pass may be more suitable for a tidal project. APIA is funded to complete a False Pass tidal feasibility study in 2012. Nikolski has superb potential for wind power development with Class 7 wind power density, moderate wind shear, bi-directional winds and low turbulence. APIA secured nearly $1M from the United States Department of Agriculture Rural Utilities Service Assistance to Rural Communities with Extremely High Energy Costs to install a 65kW wind turbine. The measured average power density and wind speed at Sand Point measured at 20m (66ft), are 424 W/m2 and 6.7 m/s (14.9 mph) respectively. Two 500kW Vestas turbines were installed and when fully integrated in 2012 are expected to provide a cost effective and clean source of electricity, reduce overall diesel fuel consumption estimated at 130,000 gallons/year and decrease air emissions associated with the consumption of diesel fuel. St. George Island has a Class 7 wind resource, which is superior for wind power development. The current strategy, led by Alaska Energy Authority, is to upgrade the St. George electrical distribution system and power plant. Avian studies in Nikolski and Sand Point have allowed for proper wind turbine siting without killing birds, especially endangered species and bald eagles. APIA continues coordinating and looking for funding opportunities for regional renewable energy projects. An important goal for APIA has been, and will continue to be, to involve community members with renewable energy projects and energy conservation efforts.

  5. Volcanoes as possible indicators of tectonic stress orientation — Aleutians and Alaska

    Microsoft Academic Search

    Kazuaki Nakamura; Klaus H. Jacob; John N. Davies

    1977-01-01

    A new method for obtaining from volcanic surface features the orientations of the principal tectonic stresses is applied to Aleutian and Alaskan volcanoes. The underlying concept for this method is that flank eruptions for polygenetic volcanoes can be regarded as the result of a large-scale natural magmafracturing experiment. The method essentially relies on the recognition of the preferred orientation of

  6. Geothermal Drilling In The Aleutians Reveals New Insights On Volcanic History Of Akutan Volcano

    NASA Astrophysics Data System (ADS)

    Stelling, P. L.

    2013-12-01

    In 2010, two thermal gradient wells were drilled in the Hot Springs Bay Valley geothermal resource area on Akutan Island, Alaska. Well TG-2 was drilled in the region of hot springs occurrence near the mouth of the valley and reached a depth of 253 m (833'). Well TG-4 was drilled near the head of the valley, closer to the current volcano, and reached a depth of 457 m (1500'). The core recovered from these wells represent the only drill core extracted from an Aleutian volcano to date and reveals an important missing piece of the surficial eruptive and erosional history of the volcano that cannot be determined from surface evaluation of recent eruptive deposits laid down on 500 ka bedrock outcrops. No intrusive rocks were encountered, indicating a rich history of surficial activity. The core is dominated (46% of recovered core) by basaltic lava flow deposits (49-52 wt% SiO2), consistent with other observed deposits on the island. These flows are interspersed with andesite lava flows (20% of core, ranging from 53-58 wt% SiO2), abundant mass wasting deposits (27% of core) and a series of ash and ash tuff layers that are some of the most silicic deposits identified at Akutan (up to 66 wt% SiO2). Ash deposits are restricted to the upper 125 m in both wells, are significantly thicker in TG-4, and are difficult to correlate between the two wells. Mass wasting deposits are diverse, including a subset characterized by matrix-supported heterolithologic breccias enclosed in a crystalline basaltic lava host. A shell-rich zone at 273 meters depth indicates that the transition between sub-marine and sub-aerial activity may be recorded in the core.

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

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

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

  8. 75 FR 50716 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-17

    ...SUPPLEMENTARY INFORMATION: Section 305(c) of the Magnuson-Stevens...emergency. Under that section, a Regional Fishery...Western Aleutian Islands golden king crab fishery. On...Western Aleutian Islands golden king crab harvested with...background information. Section...

  9. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries...Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings Area ER30AU10.000 [75 FR 53069, Aug. 30,...

  10. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries...Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings Area ER30AU10.000 [75 FR 53069, Aug. 30,...

  11. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries...Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings Area ER30AU10.000 [75 FR 53069, Aug. 30,...

  12. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries...Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings Area ER30AU10.000 [75 FR 53069, Aug. 30,...

  13. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries...Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings Area ER30AU10.000 [75 FR 53069, Aug. 30,...

  14. 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.

  15. Observations of deep long-period (DLP) seismic events beneath Aleutian arc volcanoes; 1989-2002

    USGS Publications Warehouse

    Power, J.A.; Stihler, S.D.; White, R.A.; Moran, S.C.

    2004-01-01

    Between October 12, 1989 and December 31, 2002, the Alaska Volcano Observatory (AVO) located 162 deep long-period (DLP) events beneath 11 volcanic centers in the Aleutian arc. These events generally occur at mid- to lower-crustal depths (10-45 km) and are characterized by emergent phases, extended codas, and a strong spectral peak between 1.0 and 3.0 Hz. Observed wave velocities and particle motions indicate that the dominant phases are P- and S-waves. DLP epicenters often extend over broad areas (5-20 km) surrounding the active volcanoes. The average reduced displacement of Aleutian DLPs is 26.5 cm2 and the largest event has a reduced displacement of 589 cm2 (or ML 2.5). Aleutian DLP events occur both as solitary events and as sequences of events with several occurring over a period of 1-30 min. Within the sequences, individual DLPs are often separated by lower-amplitude volcanic tremor with a similar spectral character. Occasionally, volcano-tectonic earthquakes that locate at similar depths are contained within the DLP sequences. At most, Aleutian volcanoes DLPs appear to loosely surround the main volcanic vent and occur as part of background seismicity. A likely explanation is that they reflect a relatively steady-state process of magma ascent over broad areas in the lower and middle portions of the crust. At Mount Spurr, DLP seismicity was initiated by the 1992 eruptions and then slowly declined until 1997. At Shishaldin Volcano, a short-lived increase in DLP seismicity occurred about 10 months prior to the April 19, 1999 eruption. These observations suggest a link between eruptive activity and magma flux in the mid- to lower-crust and uppermost mantle.

  16. Revisions to the Steller Sea Lion Protection Measures for the Aleutian Islands Atka Mackerel

    E-print Network

    Revisions to the Steller Sea Lion Protection Measures for the Aleutian Islands Atka Mackerel mackerel and Pacific cod fisheries. The western distinct population segment (WDPS) of Steller sea lion is declining. Atka mackerel and Pacific cod are principal prey species for Steller sea lions in the Aleutian

  17. Non-volcanic tremor in the Aleutian Islands captured by a mini-seismic array

    NASA Astrophysics Data System (ADS)

    Ghosh, A.; Prejean, S. G.

    2013-12-01

    The Aleutian Islands are an interesting place to study because of the presence of abundant seismicity, both subduction and volcano related. In addition to regular earthquakes, the Islands host both volcanic and non-volcanic tremor. To capture this rich variety of seismicity, we designed and installed a mini-seismic array on Akutan Island in 2012. Akutan is located in the eastern Aleutians just off the tip of the Alaska Peninsula, near the eastern edge of the 1957 Mw8.6 earthquake rupture zone. A mini-seismic array is particularly useful in this logistically challenging environment where land cover is limited. We recorded and analyzed about 2 months of data, and found both volcanic and non-volcanic events. Here we focus on non-volcanic tremor and its characteristics as captured by the Akutan array. Akutan Island and the surrounding area turn out to be prolific producers of tremor. An automatic beam-backprojection algorithm [Ghosh et al., 2009] detects almost daily tremor activity with durations ranging from several minutes to more than 3.5 hours. On average, beam-backprojection detects 1.3 hours of tremor activity per day and in total, it detects about 5 times more duration of tremor activity compared to a visual check for tremor signal using the existing seismic network. We observe tremor sources both west and east of the Akutan array. Western sources are the most active ones and their slowness parameters are consistent with the locations of low-frequency earthquakes detected by Brown et al., 2013. The eastern source area has not been identified previously and appears to be active for only a few times during this study, but shows continuous activity for several hours. In addition, we observe temporal evolution of slowness parameters consistent with steady tremor migration. Moreover, low frequency earthquakes with impulsive body wave phases are identified within the tremor signal. They show S-minus-P times consistent with their being located at the model plate interface [Hayes et al., 2012]. The mini-seismic array combined with a beam-backprojection algorithm is providing an enhanced image of tremor activity in the Aleutian Islands, by greatly improving the level of detection and resolution of locations. This would enable us to perform more intricate analyses of tectonic behavior of slow earthquake and tremor, their possible interaction with regular earthquakes and therefore help better understand the subduction dynamics of the study area. Comparison between tremor duration detected by the beam-backprojection and existing seismic network. On average, beam-backprojection detected ~5 times more duration of tremor activity compared to the detection using existing network.

  18. Origins of linguistic diversity in the Aleutian Islands.

    PubMed

    Berge, Anna

    2010-12-01

    The Aleut language, currently spoken along the Aleutian chain and the Pribilof and Commander islands, is the only language in its branch of the Eskimo-Aleut language family, and traditional methods of linguistic reconstruction have neither satisfactorily explained its relationship with languages on the Asian continent nor its development from Proto-Eskimo-Aleut. Linguistic reconstruction has always been important in understanding the prehistory and history of the Aleuts, and new approaches in comparative linguistics, more comprehensive information on typological features of neighboring languages, and continuing language documentation allow us to propose a rich and continuous history of contact with various groups of people. I evaluate evidence that the Aleut language may have been shaped by contact with neighbors in Asia and Alaska, eventually giving rise to its differentiation from the Eskimo languages. I look at dialect differentiation along the Aleutian chain and what this differentiation reveals about the migration trends of the Aleut along the chain. I look at the colonial expansion of the Aleut-speaking area and resulting additional varieties of Aleut in the historical period. Finally, I review the effects of the Russian and American colonial periods on the Aleut language and the severe endangerment that the language faces today as a result. I conclude that there is evidence of possible Aleut contact with both neighboring peoples; however, much of this evidence has not yet been subjected to systematic comparative reconstructions. Linguistic evidence supports theories of at least two westward expansions of Aleuts along the island chain, but it is not yet clear what motivated the dialect differentiations. Finally, I offer some thoughts on directions for future dialect studies and the continuing documentation of Aleut. PMID:21417884

  19. 76 FR 68161 - Proposed Information Collection; Comment Request; Aleutian Islands Pollock Fishery Requirements

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-03

    ...of this law allocates the Aleutian Islands (AI) directed pollock fishery to the Aleut Corporation...for activities necessary for conducting the AI directed pollock fishery. Management provisions for the AI directed pollock fishery include:...

  20. A Brown HAwk-owl (NiNox scutulata) from kiskA islAnd, AleutiAn islAnds, AlAskA

    E-print Network

    Jones, Ian L.

    ). Finally, the short-eared owls (Asio flammeus flammeus) that occur annually in the western Aleutians and Amchitka islands in the Aleutian chain (Gibson and Byrd 2007), and (probably) the long-eared owl (Asio otus

  1. Modeling potential tsunami sources for deposits near Unalaska Island, Aleutian Islands

    NASA Astrophysics Data System (ADS)

    La Selle, S.; Gelfenbaum, G. R.

    2013-12-01

    In regions with little seismic data and short historical records of earthquakes, we can use preserved tsunami deposits and tsunami modeling to infer if, when and where tsunamigenic earthquakes have occurred. The Aleutian-Alaska subduction zone in the region offshore of Unalaska Island is one such region where the historical and paleo-seismicity is poorly understood. This section of the subduction zone is not thought to have ruptured historically in a large earthquake, leading some to designate the region as a seismic gap. By modeling various historical and synthetic earthquake sources, we investigate whether or not tsunamis that left deposits near Unalaska Island were generated by earthquakes rupturing through Unalaska Gap. Preliminary field investigations near the eastern end of Unalaska Island have identified paleotsunami deposits well above sea level, suggesting that multiple tsunamis in the last 5,000 years have flooded low-lying areas over 1 km inland. Other indicators of tsunami inundation, such as a breached cobble beach berm and driftwood logs stranded far inland, were tentatively attributed to the March 9, 1957 tsunami, which had reported runup of 13 to 22 meters on Umnak and Unimak Islands, to the west and east of Unalaska. In order to determine if tsunami inundation could have reached the runup markers observed on Unalaska, we modeled the 1957 tsunami using GeoCLAW, a numerical model that simulates tsunami generation, propagation, and inundation. The published rupture orientation and slip distribution for the MW 8.6, 1957 earthquake (Johnson et al., 1994) was used as the tsunami source, which delineates a 1200 km long rupture zone along the Aleutian trench from Delarof Island to Unimak Island. Model results indicate that runup and inundation from this particular source are too low to account for the runup markers observed in the field, because slip is concentrated in the western half of the rupture zone, far from Unalaska. To ascertain if any realistic, earthquake-generated tsunami could account for the observed runup, we modeled tsunami inundation from synthetic MW 9.2 earthquakes rupturing along the trench between Atka and Unimak Islands, which indicate that the deposit runup observed on Unalaska is possible from a source of this size and orientation. Further modeling efforts will examine the April 1, 1946 Aleutian tsunami, as well as other synthetic tsunamigenic earthquake sources of varying size and location, which may provide insight into the rupture history of the Aleutian-Alaska subduction zone, especially in combination with more data from paleotsunami deposits. Johnson, Jean M., Tanioka, Yuichiro, Ruff, Larry J., Satake, Kenji, Kanamori, Hiroo, Sykes, Lynn R. "The 1957 great Aleutian earthquake." Pure and Applied Geophysics 142.1 (1994): 3-28.

  2. Volcanoes in the Infrared

    NSDL National Science Digital Library

    2008-11-04

    In this video adapted from KUAC-TV and the Geophysical Institute at the University of Alaska, Fairbanks, satellite imagery and infrared cameras are used to study and predict eruptions of volcanoes in the Aleutian Islands, Alaska.

  3. Nd and Sr isotopes in the Aleutians: multicomponent parenthood of island-arc magmas

    Microsoft Academic Search

    V. von Drach; B. D. Marsh; G. J. Wasserburg

    1986-01-01

    Young volcanic rocks from different sections of the Aleutian Islands-Alaska Peninsula Arc have been measured for 87Sr\\/86Sr, 143Nd\\/144Nd and some trace elements. We found the 143Nd\\/144Nd to be highly restricted in range (?Nd=6 to 7) and low as compared to midocean ridge ba-salts (MORB). This indicates that the source of the Aleutian Arc magmas is different from MORB and remarkably

  4. 50 CFR Table 24 to Part 679 - Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl Fishing... Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC...Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl...

  5. 50 CFR Table 24 to Part 679 - Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl Fishing... Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC...Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl...

  6. Paleomagnetic Evidence for Significant Rotations Within the Aleutian Island Arc.

    NASA Astrophysics Data System (ADS)

    Stone, D. B.; Krutikov, L.

    2006-12-01

    Present-day motion of the Pacific plate relative to the North American plate changes along the Aleutian arc from normal convergence in the east to transform motion in the west. It was postulated by Geist et al. (Tectonics 7, 327-341, 1988) that strain partitioning could result in tectonic segmentation of the lithosphere, caused by increasing obliquity of plate convergence and characterized by clockwise rotation and westward translation of discrete blocks. Their analysis of the present day morphology and tectonic setting of the western half of the arc suggests the presence of rotated blocks, and implies that the rotation is ongoing. Published high-quality paleomagnetic data from the far western end of the arc show rotations that are compatible with this model. This result is based on rocks of Eocene (Bering and Medny Islands) and Miocene (Shemya Island) age, thus the magnetically observed rotations could have occurred at any time since their origin. New paleomagnetic and geochronologic data from Miocene age volcanic rocks on Amchitka Island also indicate clockwise rotation at some time since the rocks were formed (13.8+/-0.2 Ma). However, two other high-quality paleomagnetic data sets from Eocene/Oligocene aged sediments from the eastern part of the arc (Atka and Umnak Islands) are significantly rotated in the same clockwise sense as the western end. Since plate convergence at these two eastern sites has been roughly normal since mid-Eocene time, strain partitioning related to oblique convergence is unlikely to be the cause of the rotation. Models involving rotation of the entire island arc to explain the similarity in magnitude and sense of the rotations seen in the paleomagnetic data require large relative latitude changes between the two ends of the arc. Though possible, such a model would put serious constraints on scenarios for the tectonic development of the Bering Sea Plate required to accommodate the degree of rotation suggested by the data. The answer may be that the eastern and western rotations, though similar in magnitude and sense of rotation, are unrelated in origin. The western part could have rotated in a transpressional boundary zone as proposed in the block rotation model, and the eastern part rotated in response to complex terrane collisions along the southern margin of the Alaskan collage.

  7. Three new species of heteroderoidea (nematoda) from the Aleutian Islands

    SciTech Connect

    Bernard, E.C.

    1981-10-01

    Three new species of Heteroderoidea are described from Adak and Amchitka Islands in the Aleutian chain. Second-stage juveniles of Thecavermiculatus crassicrustata, n. sp., differ from those of T. gracililancea Robbins by having longer stylets (40 to 50 ..mu..m vs 19 to 22 ..mu..m). The female of T. crassicrustata has a longer neck, a more posterior excretory pore, and lacks a posterior protuberance. Meloidodera eurytyla, n. sp., differs from other Meloidodera spp. in that second-stage juveniles have longer stylets (32 to 35 ..mu..m) and much more massive styletknobs, while males have a longitudinally striated basal head annule. Meloidogyne subarctica, n. sp., can be separated from other Meloidogyne spp. by combinations of the following characteristics: perineal pattern with large oval areas in the tail region devoid of striae, arch with few unbroken striae; female excretory pore 1.5 to 2.5 x the stylet length from the anterior end; haploid chromosome number = 18; the spermatheca filled with sperm; stylet length of second-stage juveniles 13.5 to 15.4 ..mu..m.

  8. Hair methylmercury levels of mummies of the Aleutian Islands, Alaska

    SciTech Connect

    Egeland, G.M. [Centre for Indigenous Peoples' Nutrition and Environment (CINE), McGill University, 21, 111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, H9X 3V9 (Canada)], E-mail: grace.egeland@mcgill.ca; Ponce, Rafael [Toxicology, Amgen WA, 1201 Amgen Court West, Seattle, WA 981119 (United States)], E-mail: rponce@amgen.com; Bloom, Nicolas S. [Studio Geochimica, 4744 University Way NE, Seattle, WA 98105 (United States)], E-mail: nicolasb@nickslab.org; Knecht, Rick [Department of Alaska Native and Rural Development, University of Alaska, Fairbanks, 221 E. Northern Lights Boulevard, Suite 213, Anchorage, AK 99508-4143 (United States)], E-mail: Knecht@palaunet.com; Loring, Stephen [Arctic Studies Center, Smithsonian Institution, National Museum of Natural History, P.O. Box 37012, Washington, DC 20013-7012 (United States)], E-mail: lorings@si.edu; Middaugh, John P. [Nevada Department of Health and Human Services, 4150 Technology Way, Carson City, NV 89706 (United States)], E-mail: middaugh@SNHDMAIL.ORG

    2009-04-15

    Ancient human hair specimens can shed light on the extent of pre-historic exposures to methylmercury and provide valuable comparison data with current-day exposures, particularly for Indigenous Peoples who continue to rely upon local traditional food resources. Human hair from ancient Aleutian Island Native remains were tested for total and methylmercury (Hg, MeHg) and were radiocarbon dated. The remains were approximately 500 years old (1450 A.D.). For four adults, the mean and median total hair mercury concentration was 5.8 ppm (SD=0.9). In contrast, MeHg concentrations were lower with a mean of 1.2 ppm (SD=1.8) and a median of 0.54 ppm (0.12-3.86). For the five infants, the mean and median MeHg level was 1.2 ppm (SD=1.8) and 0.20 ppm (0.007-4.61), respectively. Segmental analyses showed variations in MeHg concentrations in 1-cm segments, consistent with fluctuations in naturally occurring exposure to mercury through dietary sources. The levels are comparable to or lower than those found in fish and marine mammal-eating populations today who rely far less on subsistence food than pre-historic humans. The findings are, therefore, compatible with increased anthropogenic release of trace metals during the past several centuries.

  9. Steller Sea Lion Protection Measures for Groundfish Fisheries in the Bering Sea and Aleutian Islands

    E-print Network

    Islands Management Area Draft Environmental Impact Statement/Regulatory Impact Review/Initial Regulatory in the Bering Sea and Aleutian Islands Management Area Draft Environmental Impact Statement/Regulatory Impact. Fish and Wildlife Service Alaska Department of Fish and Game Abstract: This environmental impact

  10. Volcanic and tectonic deformation on Unimak Island in the Aleutian Arc, Alaska

    E-print Network

    Segall, Paul

    Volcanic and tectonic deformation on Unimak Island in the Aleutian Arc, Alaska Do¨rte Mann1 and Jeffrey Freymueller Geophysical Institute, University of Alaska, Fairbanks, Alaska, USA Received 13 April, Alaska, Unimak Island Citation: Mann, D., and J. Freymueller, Volcanic and tectonic deformation on Unimak

  11. 77 FR 44172 - Fisheries of the Exclusive Economic Zone Off Alaska; Squid in the Bering Sea and Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-27

    ...the Exclusive Economic Zone Off Alaska; Squid in the Bering Sea and Aleutian Islands...to the initial total allowable catch of squid in the Bering Sea and Aleutian Islands...initial total allowable catch (ITAC) of squid in the BSAI was established as 361...

  12. 76 FR 55276 - Fisheries of the Exclusive Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian Islands

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ...the Exclusive Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian Islands...SUMMARY: NMFS is prohibiting retention of octopus in the Bering Sea and Aleutian Islands...because the 2011 total allowable catch of octopus in the BSAI has been reached....

  13. Gabbroic and Peridotitic Enclaves from the 2008 Kasatochi Eruption, Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Kentner, A.; Nadin, E. S.; Izbekov, P. E.; Nye, C. J.; Neill, O. K.

    2012-12-01

    Kasatochi volcano of the Andreanof Islands in the western Aleutian Arc violently erupted over a two day period from August 7-8, 2008. The eruption involved multiple explosive events generating pyroclastic flows, which included abundant mafic and ultramafic enclaves that have since weathered out and accumulated in talus along the coast. These and other mafic enclaves sampled by modern island arc lavas provide insight into subduction magmatism because they emerge from a section of the subduction system that is less likely than shallower zones to be modified by magmatic processes such as mixing, assimilation, or fractionation. We present new whole rock, clinopyroxene, amphibole, plagioclase, and melt compositions from Kasatochi enclaves of the 2008 eruption. The highly crystalline (~40 vol. % phenocryst content), medium-K basaltic andesite host rock contains ~52-55 wt. % SiO2 and 0.6-0.9 wt. % K2O, and is composed of plagioclase, ortho- and clinopyroxene, amphibole, and Ti-magnetite in a microlite-rich groundmass. Upon eruption, this magma sampled two distinct enclave populations: gabbro and peridotite. The gabbro has abundant amphibole (mostly magnesio-hastingsite) and plagioclase with minor clinopyroxene, olivine, and magnetite, while the peridotite is composed of olivine with minor amounts of clinopyroxene and orthopyroxene. There is little textural variation amongst the peridotitic samples collected, but the gabbroic samples vary from layered to massive and cover a range in grain size from fine-grained to pegmatitic. The layered gabbros display centimeter-scale bands of alternating plagioclase- and amphibole-rich layers, with a strong preferential alignment of the amphibole grains. The coarser-grained samples are very friable, with ~10% pore space; disaggregation of these upon host-magma ascent likely formed the amphibole and plagioclase xenocrysts in the andesitic host. Based on the textural and compositional differences, we divide the enclaves into four groups, (1) fine-grained gabbro, (2) medium- to coarse-grained gabbro, (3) pegmatitic gabbro with crystals up to 11 cm long, and (4) medium-grained peridotite. Bulk analyses of the gabbros using LA-ICP-MS show strong light rare-earth element depletion typical of primitive melts and arc volcanics such as the South Sandwich Arc. Our data suggest that the enclaves are primitive, with plagioclase compositions of An92-96 and crystallization temperatures of 900-1100 deg. C. Initial thermobarometric analyses from compositions of amphibole in the gabbroic samples suggest different temperature-pressure conditions for crystallization of fine-grained and very coarse-grained gabbros. We interpret these rocks as hydrous cumulate-melt mixtures with primitive geochemistry that is similar to Aleutian xenoliths of Kanaga Island.

  14. Revisions to the Steller Sea Lion Protection Measures for the Bering Sea and Aleutian Islands

    E-print Network

    Revisions to the Steller Sea Lion Protection Measures for the Bering Sea and Aleutian Islands of the environmental, social, and economic effects of alternatives to the Steller sea lion protection measures and Pacific cod fisheries. The western distinct population segment (WDPS) of Steller sea lion is listed

  15. 78 FR 46577 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-01

    ...and Aleutian Islands Crab Rationalization Cost Recovery Program AGENCY: National Marine...notification of a 0.69-percent fee for cost recovery under the Bering Sea and Aleutian...can calculate the required payment for cost recovery fees that must be submitted...

  16. 77 FR 44216 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-27

    ...and Aleutian Islands Crab Rationalization Cost Recovery Program AGENCY: National Marine...notification of a zero (0) percent fee for cost recovery under the Bering Sea and Aleutian...Magnuson-Stevens Act). The Program includes a cost recovery provision to collect fees to...

  17. 75 FR 43147 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-23

    ...and Aleutian Islands Crab Rationalization Cost Recovery Program AGENCY: National Marine...notification of a 2.67-percent fee for cost recovery under the Bering Sea and Aleutian...can calculate the required payment for cost recovery fees that must be submitted...

  18. 76 FR 43658 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-21

    ...and Aleutian Islands Crab Rationalization Cost Recovery Program AGENCY: National Marine...notification of a 1.23-percent fee for cost recovery under the Bering Sea and Aleutian...can calculate the required payment for cost recovery fees that must be submitted...

  19. Condition of groundfish resources of the eastern Bering Sea and Aleutian Islands region in 1982

    SciTech Connect

    Bakkala, R.G.; Low, L.; Ito, D.H.; Narita, R.E.; Ronholt, L.L.

    1983-03-01

    This report contains an assessment of the condition of groundfish and squid in the eastern Bering Sea and Aleutian Islands region through 1982. The assessments are based on species-by-species analyses of the data collected from the commercial fishery and research vessel surveys. Most of the resources in the Bering Sea-Aleutians management region are in good condition, including walleye pollock, Pacific cod, the flatfishes, and Atka mackerel. Pacific cod and yellowfin sole are in excellent condition and at historic high levels of abundance.

  20. Crustal structure transition from oceanic arc to continental arc, eastern Aleutian Islands and Alaska Peninsula

    Microsoft Academic Search

    Moritz M. Fliedner; Simon L. Klemperer

    2000-01-01

    The Aleutian island arc crosses from the Pacific Ocean to the North-American continent at the island of Unimak. 3-D finite-difference traveltime inversion of our onshore–offshore seismic reflection\\/refraction data gives a velocity model of the crust and uppermost mantle. The arc crust is on average 30 km thick, but thickens to almost 40 km under the western Alaska Peninsula. The transition

  1. Chemical versus temporal controls on the evolution of tholeiitic and calc-alkaline magmas at two volcanoes in the Alaska-Aleutian arc

    USGS Publications Warehouse

    George, R.; Turner, S.; Hawkesworth, C.; Bacon, C.R.; Nye, C.; Stelling, P.; Dreher, S.

    2004-01-01

    The Alaska-Aleutian island arc is well known for erupting both tholeiitic and calc-alkaline magmas. To investigate the relative roles of chemical and temporal controls in generating these contrasting liquid lines of descent we have undertaken a detailed study of tholeiitic lavas from Akutan volcano in the oceanic A1eutian arc and calc-alkaline products from Aniakchak volcano on the continental A1askan Peninsula. The differences do not appear to be linked to parental magma composition. The Akutan lavas can be explained by closed-system magmatic evolution, whereas curvilinear trace element trends and a large range in 87 Sr/86 Sr isotope ratios in the Aniakchak data appear to require the combined effects of fractional crystallization, assimilation and magma mixing. Both magmatic suites preserve a similar range in 226 Ra-230 Th disequilibria, which suggests that the time scale of crustal residence of magmas beneath both these volcanoes was similar, and of the order of several thousand years. This is consistent with numerical estimates of the time scales for crystallization caused by cooling in convecting crustal magma chambers. During that time interval the tholeiitic Akutan magmas underwent restricted, closed-system, compositional evolution. In contrast, the calc-alkaline magmas beneath Aniakchak volcano underwent significant open-system compositional evolution. Combining these results with data from other studies we suggest that differentiation is faster in calc-alkaline and potassic magma series than in tholeiitic series, owing to a combination of greater extents of assimilation, magma mixing and cooling.

  2. 50 CFR 600.1108 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false...Aleutian Islands (BSAI) non-pollock groundfish fishery program. 600.1108 Section 600.1108 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT,...

  3. 50 CFR 600.1108 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false...Aleutian Islands (BSAI) non-pollock groundfish fishery program. 600.1108 Section 600.1108 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT,...

  4. Influence of mesoscale anticyclonic eddies on zooplankton distribution south of the western Aleutian Islands during summer

    NASA Astrophysics Data System (ADS)

    Saito, R.; Yamaguchi, A.; Yasuda, I.; Ueno, H.; Ishiyama, H.; Imai, I.

    2013-12-01

    Mesoscale anticyclonic eddies have been observed south of the Aleutian Islands located between the Bering Sea and the subarctic Pacific. Eddies farther east, in the Gulf of Alaska, are known to transport coastal water and coastal zooplankton to offshore open ocean. The impacts of mesoscale anticyclonic eddies formed south of the western Aleutian Islands (Aleutian eddies) on the zooplankton community are not fully understood. In the present study, we describe zooplankton population structures within an Aleutian eddy and outside the eddy during July 2010. Our field study was conducted at seven stations along 51°15?N from 171°21?E to 174°38?E (western line) and at four stations along 50°40?N from 176°24?E to 178°44?E (eastern line) on 7-8 July 2010. At each station, environmental data (temperature, salinity and fluorescence were measured by CTD/XCTD. Zooplankton samples were collected by vertical tow of 150 m depth to the surface using 100 ?m mesh size plankton net. Based on the sea level anomaly (SLA), the western line crossed an anticyclonic eddy but the eastern line did not cross the eddy (Fig. 1). This Aleutian eddy was formed south of Attu Island (52°54?N, 172°54?E) in mid-February 2010, and it moved southeastward in the next five months. The SLA near the eddy center, representing the strength of the eddy, continuously increased, and the area oscillated at one to two month periods overlain on a general increase from ~7,000 to ~18,000 km2. Large oceanic copepods, Neocalanus cristatus, Eucalanus bungii and Metridia pacifica were more abundant inside the eddy than the outside. Inside the eddy, the life stage distribution of N. cristatus was advanced than that outside, and Neocalanus spp. had accumulated more lipids. These conditions probably reflect the greater primary production in the eddy, production enhanced by nutrients advected into the eddy. Since the Aleutian eddy was formed in offshore waters and/or eddy-eddy interaction occurred after its formation, it contained mostly oceanic copepods. The sufficient food condition in the eddy presumably induced higher growth and survival rates of these oceanic copepods, resulting in the greater abundance, advanced development stages and greater lipid accumulation. Fig. 1. Sea level anomaly along the sampling lines on 7 July 2010 south of the western Aleutian Islands.

  5. Geology and geochemistry of the Geyser Bight Geothermal Area, Umnak Island, Aleutian Islands, Alaska

    SciTech Connect

    Nye, C.J. (Alaska Univ., Fairbanks, AK (USA). Geophysical Inst. Alaska Dept. of Natural Resources, Fairbanks, AK (USA). Div. of Geological and Geophysical Surveys); Motyka, R.J. (Alaska Dept. of Natural Resources, Juneau, AK (USA). Div. of Geological and Geophysical Surveys); Turner, D.L. (Alaska Univ., Fairbanks, AK (USA). Geophysical Inst.); Liss, S.A. (Alaska Dept. of Natural Resources, Fairba

    1990-10-01

    The Geyser Bight geothermal area is located on Umnak Island in the central Aleutian Islands. It contains one of the hottest and most extensive areas of thermal springs and fumaroles in Alaska, and is only documented site in Alaska with geysers. The zone of hot springs and fumaroles lies at the head of Geyser Creek, 5 km up a broad, flat, alluvial valley from Geyser Bight. At present central Umnak is remote and undeveloped. This report describes results of a combined program of geologic mapping, K-Ar dating, detailed description of hot springs, petrology and geochemistry of volcanic and plutonic rock units, and chemistry of geothermal fluids. Our mapping documents the presence of plutonic rock much closer to the area of hotsprings and fumaroles than previously known, thus increasing the probability that plutonic rock may host the geothermal system. K-Ar dating of 23 samples provides a time framework for the eruptive history of volcanic rocks as well as a plutonic cooling age.

  6. The Detection, Characterization and Tracking of Recent Aleutian Island Volcanic Ash Plumes and the Assessment of Their Impact on Aviation

    NASA Technical Reports Server (NTRS)

    Murray, John J.; Hudnall, L. A.; Matus, A.; Krueger, A. J.; Trepte, C. r.

    2010-01-01

    The Aleutian Islands of Alaska are home to a number of major volcanoes which periodically present a significant hazard to aviation. During summer of 2008, the Okmok and Kasatochi volcanoes experienced moderate eruptive events. These were followed a dramatic, major eruption of Mount Redoubt in late March 2009. The Redoubt case is extensively covered in this paper. Volcanic ash and SO2 from each of these eruptions dispersed throughout the atmosphere. This created the potential for major problems for air traffic near the ash dispersions and at significant distances downwind. The NASA Applied Sciences Weather Program implements a wide variety of research projects to develop volcanic ash detection, characterization and tracking applications for NASA Earth Observing System and NOAA GOES and POES satellites. Chemistry applications using NASA AURA satellite Ozone Monitoring System (OMI) retrievals produced SO2 measurements to trace the dispersion of volcanic aerosol. This work was complimented by advanced multi-channel imager applications for the discrimination and height assignment of volcanic ash using NASA MODIS and NOAA GOES and POES imager data. Instruments similar to MODIS and OMI are scheduled for operational deployment on NPOESS. In addition, the NASA Calipso satellite provided highly accurate measurements of aerosol height and dispersion for the calibration and validation of these algorithms and for corroborative research studies. All of this work shortens the lead time for transition to operations and ensures that research satellite data and applications are operationally relevant and utilized quickly after the deployment of operational satellite systems. Introduction

  7. A new population of Aleutian shield fern (Polystichum aleuticum C. Christens.) on Adak Island, Alaska

    USGS Publications Warehouse

    Talbot, S.L.; Talbot, S. S.

    2002-01-01

    We report and describe a new population of the endangered Aleutian shield fern (Polystichum aleuticum C. Christens.) discovered on Mount Reed, Adak Island, Alaska. The new population is located at a lower elevation than the other known populations, placing the species' known elevational range between 338 m and 525 m. The discovery of this population is significant because it increases the total number of known populations and individuals for the species.

  8. EarthScope: Activity at Augustine Volcano

    NSDL National Science Digital Library

    This bulletin provides information on the recent eruptive activity of Augustine Volcano in Alaska. Topics include some history of the volcano, its geologic setting as part of the Aleutian island arc, and earthquake locations as indicators of magma movement. The bulletin is also accompanied by a 360-degree rotation around the volcano and background information on the EarthScope Project.

  9. Microbial consortia of gorgonian corals from the Aleutian islands

    USGS Publications Warehouse

    Gray, Michael A.; Stone, R.P.; McLaughlin, M.R.; Kellogg, C.A.

    2011-01-01

    Gorgonians make up the majority of corals in the Aleutian archipelago and provide critical fish habitat in areas of economically important fisheries. The microbial ecology of the deep-sea gorgonian corals Paragorgea arborea, Plumarella superba, and Cryogorgia koolsae was examined with culture-based and 16S rRNA gene-based techniques. Six coral colonies (two per species) were collected. Samples from all corals were cultured, and clone libraries were constructed from P. superba and C. koolsae. Cultured bacteria were dominated by the Gammaproteobacteria, especially Vibrionaceae, with other phyla comprising <6% of the isolates. The clone libraries showed dramatically different bacterial communities between corals of the same species collected at different sites, with no clear pattern of conserved bacterial consortia. Two of the clone libraries (one from each coral species) were dominated by Tenericutes, with Alphaproteobacteria dominating the remaining sequences. The other libraries were more diverse and had a more even distribution of bacterial phyla, showing more similarity between genera than within coral species. Here we report the first microbiological characterization of P. arborea, P. superba, and C. koolsae. FEMS Microbiology Ecology ?? 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. No claim to original US government works.

  10. Dispersal and behavior of pacific halibut hippoglossus stenolepis in the bering sea and Aleutian islands region

    USGS Publications Warehouse

    Seitz, A.C.; Loher, T.; Norcross, B.L.; Nielsen, J.L.

    2011-01-01

    Currently, it is assumed that eastern Pacific halibut Hippoglossus stenolepis belong to a single, fully mixed population extending from California through the Bering Sea, in which adult halibut disperse randomly throughout their range during their lifetime. However, we hypothesize that hali but dispersal is more complex than currently assumed and is not spatially random. To test this hypo thesis, we studied the seasonal dispersal and behavior of Pacific halibut in the Bering Sea and Aleutian Islands (BSAI). Pop-up Archival Transmitting tags attached to halibut (82 to 154 cm fork length) during the summer provided no evidence that individuals moved out of the Bering Sea and Aleutian Islands region into the Gulf of Alaska during the mid-winter spawning season, supporting the concept that this region contains a separate spawning group of adult halibut. There was evidence for geographically localized groups of halibut along the Aleutian Island chain, as all of the individuals tagged there displayed residency, with their movements possibly impeded by tidal currents in the passes between islands. Mid-winter aggregation areas of halibut are assumed to be spawning grounds, of which 2 were previously unidentified and extend the species' presumed spawning range ~1000 km west and ~600 km north of the nearest documented spawning area. If there are indeed independent spawning groups of Pacific halibut in the BSAI, their dynamics may vary sufficiently from those of the Gulf of Alaska, so that specifically accounting for their relative segregation and unique dynamics within the larger population model will be necessary for correctly predicting how these components may respond to fishing pressure and changing environmental conditions.?? Inter-Research 2011.

  11. Ecosystem Models of the Aleutian Islands and Southeast Alaska Show that Steller Sea Lions are Impacted by Killer Whale Predation when Sea Lion

    E-print Network

    Ecosystem Models of the Aleutian Islands and Southeast Alaska Show that Steller Sea Lions are Impacted by Killer Whale Predation when Sea Lion Numbers are Low Sylvie Guénette1,2 , Sheila J.J. Heymans1 lions since the late 1970s in the central and western Aleutian Islands. We also sought to understand why

  12. An introduced predator alters Aleutian Island plant communities by thwarting nutrient subsidies

    USGS Publications Warehouse

    Maron, J.L.; Estes, J.A.; Croll, D.A.; Danner, E.M.; Elmendorf, S.C.; Buckelew, S.L.

    2006-01-01

    The ramifying effects of top predators on food webs traditionally have been studied within the framework of trophic cascades. Trophic cascades are compelling because they embody powerful indirect effects of predators on primary production. Although less studied, indirect effects of predators may occur via routes that are not exclusively trophic. We quantified how the introduction of foxes onto the Aleutian Islands transformed plant communities by reducing abundant seabird populations, thereby disrupting nutrient subsidies vectored by seabirds from sea to land. We compared soil and plant fertility, plant biomass and community composition, and stable isotopes of nitrogen in soil, plants, and other organisms on nine fox-infested and nine historically fox-free islands across the Aleutians. Additionally, we experimentally augmented nutrients on a fox-infested island to test whether differences in plant productivity and composition between fox-infested and fox-free islands could have arisen from differences in nutrient inputs between island types. Islands with historical fox infestations had soils low in phosphorus and nitrogen and plants low in tissue nitrogen. Soils, plants, slugs, flies, spiders, and bird droppings on these islands had low d15N values indicating that these organisms obtained nitrogen from internally derived sources. In contrast, soils, plants, and higher trophic level organisms on fox-free islands had elevated d15N signatures indicating that they utilized nutrients derived from the marine environment. Furthermore, soil phosphorus (but not nitrogen) and plant tissue nitrogen were higher on fox-free than fox-infested islands. Nutrient subsidized fox-free islands supported lush, high biomass plant communities dominated by graminoids. Fox-infested islands were less graminoid dominated and had higher cover and biomass of low-lying forbs and dwarf shrubs. While d15N profiles of soils and plants and graminoid biomass varied with island size and distance from shore, after accounting for these effects differences between fox-infested and fox-free islands still existed. Fertilization over four years caused a 24-fold increase in graminoid biomass and a shift toward a more graminoid dominated plant community typical of fox-free islands. These results indicate that apex predators can influence plant productivity and composition through complex interaction web pathways involving both top-down forcing and bottom-up nutrient exchanges across systems. ?? 2006 by the Ecological Society of America.

  13. Status and distribution of the Kittlitz's Murrelet Brachyramphus brevirostris along the Alaska Peninsula and Kodiak and Aleutian Islands, Alaska

    USGS Publications Warehouse

    Madison, Erica N.; Piatt, John F.; Arimitsu, Mayumi L.; Romano, Marc D.; van Pelt, Thomas I.; Nelson, S. Kim; Williams, Jeffrey C.; DeGange, Anthony R.

    2011-01-01

    The Kittlitz's Murrelet Brachyramphus brevirostris is adapted for life in glacial-marine ecosystems, being concentrated in the belt of glaciated fjords in the northern Gulf of Alaska from Glacier Bay to Cook Inlet. Most of the remaining birds are scattered along coasts of the Alaska Peninsula and Aleutian Islands, where they reside in protected bays and inlets, often in proximity to remnant glaciers or recently deglaciated landscapes. We summarize existing information on Kittlitz's Murrelet in this mainly unglaciated region, extending from Kodiak Island in the east to the Near Islands in the west. From recent surveys, we estimated that ~2400 Kittlitz's Murrelets were found in several large embayments along the Alaska Peninsula, where adjacent ice fields feed silt-laden water into the bays. On Kodiak Island, where only remnants of ice remain today, observations of Kittlitz's Murrelets at sea were uncommon. The species has been observed historically around the entire Kodiak Archipelago, however, and dozens of nest sites were found in recent years. We found Kittlitz's Murrelets at only a few islands in the Aleutian chain, notably those with long complex shorelines, high mountains and remnant glaciers. The largest population (~1600 birds) of Kittlitz's Murrelet outside the Gulf of Alaska was found at Unalaska Island, which also supports the greatest concentration of glacial ice in the Aleutian Islands. Significant populations were found at Atka (~1100 birds), Attu (~800) and Adak (~200) islands. Smaller numbers have been reported from Unimak, Umnak, Amlia, Kanaga, Tanaga, Kiska islands, and Agattu Island, where dozens of nest sites have been located in recent years. Most of those islands have not been thoroughly surveyed, and significant pockets of Kittlitz's Murrelets may yet be discovered. Our estimate of ~6000 Kittlitz's Murrelets along the Alaska Peninsula and Aleutian Islands is also likely to be conservative because of the survey protocols we employed (i.e. early seasonal timing of surveys, strip transects).

  14. Satellite monitoring of remote volcanoes improves study efforts in Alaska

    Microsoft Academic Search

    K. Dean; M. Servilla; A. Roach; B. Foster; K. Engle

    1998-01-01

    Satellite monitoring of remote volcanoes is greatly benefitting the Alaska Volcano Observatory (AVO), and last year's eruption of the Okmok Volcano in the Aleutian Islands is a good case in point. The facility was able to issue and refine warnings of the eruption and related activity quickly, something that could not have been done using conventional seismic surveillance techniques, since

  15. The 1817 Eruption of Okmok Caldera, Umnak Island, Alaska: New Insights Into a Complex Historical Eruption in the Eastern Aleutians

    NASA Astrophysics Data System (ADS)

    Neal, C. A.; Beget, J.; Grey, D.; Wolfe, B.

    2003-12-01

    Okmok is a 10-km-diameter, late-Holocene caldera on Umnak Island in the eastern Aleutians, 1400 km southwest of Anchorage. The most recent eruption in 1997 was strombolian in character, producing a basaltic-andesite lava flow within the caldera and localized ash fall. Since caldera-formation approximately 2050 14C yrs BP, however, more violent eruptions from vents within the caldera have impacted all flanks of the volcano with tephra fall, ballistics, pyroclastic surges and flows, and lahars. An example of these more violent intracaldera events is the 1817 eruption. Reevaluation of historical accounts of activity at Okmok combined with new geologic mapping and tephra studies suggest that an 1817 eruption included (1) early, largely hydrovolcanic, explosive activity and the production of significant pyroclastic fall and surge deposits extending down the north and east flanks of the volcano; (2) generation of a flood that reached the Bering Sea; (3) late-stage strombolian fountaining and lava flow production. Vents from the 1817 eruption form a 4-km-long arc that parallels the base of the north caldera wall and include a 50-70-m-deep, elongate maar crater erupted through pre-existing tuff cone deposits. Terrace morphology and flood deposits less than 200 14C yrs BP indicate a flooding event down Crater Creek consistent with historical accounts of Aleut village inundation at the coastline in 1817. The later part of the eruption produced a 120-m high cinder and spatter cone and a blocky a'a lava flow field that fills a shallow basin near the outlet of Crater Creek. These preliminary results indicate that Okmok is capable of eruptions far more violent than the largely effusive events of the last century.

  16. Alaska Open-file Report 144 Assessment of Thermal Springs Sites Aleutian Arc, Atka Island to Becherof Lake -- Preliminary Results and Evaluation

    SciTech Connect

    Motyka, R.J.; Moorman, M.A.; Liss, S.A.

    1981-12-01

    Twenty of more than 30 thermal spring areas reported to exist in the Aleutian arc extending from Atka Island to Becherof Lake were investigated during July and August, 1980. Thermal activity of three of these sites had diminished substantially or no longer existed. At least seven more sites where thermal-spring activity is probable or certain were not visited because of their remoteness or because of time constraints. The existence of several other reported thermal spring sites could not be verified; these sites are considered questionable. On the basis of geothermometry, subsurface reservoir temperatures in excess of 150 C are estimated for 10 of the thermal spring sites investigated. These sites all occur in or near regions of Recent volcanism. Five of the sites are characterized by fumaroles and steaming ground, indicating the presence of at least a shallow vapor-dominated zone. Two, the Makushin Valley and Glacier Valley thermal areas, occur on the flanks of active Mukushin Volcano located on Unalaska Island, and may be connected to a common source of heat. Gas geothermometry suggests that the reservoir feeding the Kliuchef thermal field, located on the flanks of Kliuchef volcano of northeast Atka Island, may be as high as 239 C.

  17. Insights Into Aleutian Volcanism from Insar Observations

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Dzurisin, D.

    2013-12-01

    With its global coverage and all-weather imaging capability, interferometric synthetic aperture radar (InSAR) has become an increasingly important technique for studying magma dynamics at volcanoes in remote regions, such as the Aleutian Islands. The spatial distribution of surface deformation derived from InSAR data enables the construction of detailed mechanical models to enhance the study of magmatic processes. To study Aleutian volcanism, we processed nearly 12,000 SAR images acquired by ERS-1, JERS-1, ERS-2, Radarsat-1, Envisat, ALOS, and TerraSAR-X from the early 1990s to 2010. We combined these SAR images to produce about 25,000 interferograms, which we analyzed for evidence of surface deformation at most of the arc's Holocene volcanoes. Where surface displacements were sufficiently strong, we used analytical models to estimate the location, shape, and volume change of deformation sources. This paper summarizes deformation processes at Aleutian volcanoes observed with InSAR, including: (1) time-variant volcanic inflation and magmatic intrusion, (2) deformation preceding and accompanying seismic swarms , (3) persistent volcano-wide subsidence at calderas that last erupted tens of years ago, (4) episodic magma intrusion and associated tectonic stress release, (5) subsidence caused by a decrease in pore fluid pressure in active hydrothermal systems, (6) subsidence of surface lava and pyroclastic flows, and (7) a lack of deformation at some volcanoes with recent eruptions, where deformation might be expected. Among the inferred mechanisms are magma accumulation in and withdrawal from crustal magma reservoirs, pressurization/depressurization of hydrothermal systems, and thermo-elastic contraction of young lava flows. Our work demonstrates that deformation patterns and associated magma supply mechanisms at Aleutian volcanoes are diverse and vary in both space and time. By combining InSAR results with information from the geologic record, accounts of historical eruptions, and data from seismology, petrology, gas geochemistry, and other sources, we have developed conceptual models for the magma plumbing systems and behaviors of many volcanoes in the Aleutian arc. We realize that these models are simplistic, but it is our hope that they will serve as foundations that will be refined as additional information becomes available. Finally, we have compared our InSAR observations from the Aleutians with those from the Andes and Indonesia to highlight the similarities and differences in volcanism between volcanic arcs [Lu and Dzurisin, 2013]. Lu, Z., and D. Dzurisin, InSAR Imaging of Aleutian Volcanoes: Monitoring a Volcanic Arc from Space', Springer Praxis Books, Geophysical Sciences, ISBN 978-3-642-00347-9, December 2013.

  18. 50 CFR Figure 6 to Subpart E of... - Alaska Peninsula and Aleutian Islands Rural and Non-Rural Areas

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Peninsula and Aleutian Islands Rural and Non-Rural Areas 6 Figure 6 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL...Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 6 Figure 6 to Subpart E of Part 300—Alaska...

  19. 50 CFR Figure 6 to Subpart E of... - Alaska Peninsula and Aleutian Islands Rural and Non-Rural Areas

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Peninsula and Aleutian Islands Rural and Non-Rural Areas 6 Figure 6 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL...Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 6 Figure 6 to Subpart E of Part 300—Alaska...

  20. 50 CFR Figure 6 to Subpart E of... - Alaska Peninsula and Aleutian Islands Rural and Non-Rural Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Peninsula and Aleutian Islands Rural and Non-Rural Areas 6 Figure 6 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL...Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 6 Figure 6 to Subpart E of Part 300—Alaska...

  1. 50 CFR Figure 6 to Subpart E of... - Alaska Peninsula and Aleutian Islands Rural and Non-Rural Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Peninsula and Aleutian Islands Rural and Non-Rural Areas 6 Figure 6 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL...Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 6 Figure 6 to Subpart E of Part 300—Alaska...

  2. Status, behavior and demography of Whiskered Auklets (Aethia pygmaea) at Egg Island, Aleutian Islands, Alaska

    E-print Network

    Jones, Ian L.

    representative Whiskered Auklet breeding habitat present. These were: Area A (53º 51.920' N 166º 03.288' W), Area B (53º 51.924' N 166º 03.217' W), Area C (53º 51.929' N 166º 03.324' W), and Area D (53º 51.924' N). Whiskered Auklet colonies in the Unimak pass area of the eastern Aleutians represent the eastern edge

  3. Little late Holocene strain accumulation and release on the Aleutian megathrust below the Shumagin Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Witter, Robert C.; Briggs, Richard W.; Engelhart, Simon E.; Gelfenbaum, Guy; Koehler, Richard D.; Barnhart, William D.

    2014-04-01

    Can a predominantly creeping segment of a subduction zone generate a great (M > 8) earthquake? Despite Russian accounts of strong shaking and high tsunamis in 1788, geodetic observations above the Aleutian megathrust indicate creeping subduction across the Shumagin Islands segment, a well-known seismic gap. Seeking evidence for prehistoric great earthquakes, we investigated Simeonof Island, the archipelago's easternmost island, and found no evidence for uplifted marine terraces or subsided shorelines. Instead, we found freshwater peat blanketing lowlands, and organic-rich silt and tephra draping higher glacially smoothed bedrock. Basal peat ages place glacier retreat prior to 10.4 ka and imply slowly rising (<0.2 m/ka) relative sea level since ~3.4 ka. Storms rather than tsunamis probably deposited thin, discontinuous deposits in coastal sites. If rupture of the megathrust beneath Simeonof Island produced great earthquakes in the late Holocene, then coseismic uplift or subsidence was too small (?0.3 m) to perturb the onshore geologic record.

  4. Little late Holocene strain accumulation and release on the Aleutian megathrust below the Shumagin Islands, Alaska

    USGS Publications Warehouse

    Witter, Robert C.; Briggs, Richard W.; Engelhart, Simon E.; Gelfenbaum, Guy R.; Koehler, Richard D.; Barnhart, William D.

    2014-01-01

    Can a predominantly creeping segment of a subduction zone generate a great (M?>?8) earthquake? Despite Russian accounts of strong shaking and high tsunamis in 1788, geodetic observations above the Aleutian megathrust indicate creeping subduction across the Shumagin Islands segment, a well-known seismic gap. Seeking evidence for prehistoric great earthquakes, we investigated Simeonof Island, the archipelago's easternmost island, and found no evidence for uplifted marine terraces or subsided shorelines. Instead, we found freshwater peat blanketing lowlands, and organic-rich silt and tephra draping higher glacially smoothed bedrock. Basal peat ages place glacier retreat prior to 10.4?ka and imply slowly rising (<0.2?m/ka) relative sea level since ~3.4?ka. Storms rather than tsunamis probably deposited thin, discontinuous deposits in coastal sites. If rupture of the megathrust beneath Simeonof Island produced great earthquakes in the late Holocene, then coseismic uplift or subsidence was too small (?0.3?m) to perturb the onshore geologic record.

  5. Feasibility of Tidal and Ocean Current Energy in False Pass, Aleutian Islands, Alaska FINAL REPORT

    SciTech Connect

    Wright, Bruce Albert [Aleutian Pribilof Islands Association] [Aleutian Pribilof Islands Association

    2014-05-07

    The Aleutian Pribilof Islands Association was awarded a U.S. Department of Energy Tribal Energy Program grant (DE-EE0005624) for the Feasibility of Tidal and Ocean Current Energy in False Pass, Aleutian Islands, Alaska (Project). The goal of the Project was to perform a feasibility study to determine if a tidal energy project would be a viable means to generate electricity and heat to meet long-term fossil fuel use reduction goals, specifically to produce at least 30% of the electrical and heating needs of the tribally-owned buildings in False Pass. The Project Team included the Aleut Region organizations comprised of the Aleutian Pribilof Island Association (APIA), and Aleutian Pribilof Island Community Development Association (APICDA); the University of Alaska Anchorage, ORPC Alaska a wholly-owned subsidiary of Ocean Renewable Power Company (ORPC), City of False Pass, Benthic GeoScience, and the National Renewable Energy Laboratory (NREL). The following Project objectives were completed: collected existing bathymetric, tidal, and ocean current data to develop a basic model of current circulation at False Pass, measured current velocities at two sites for a full lunar cycle to establish the viability of the current resource, collected data on transmission infrastructure, electrical loads, and electrical generation at False Pass, performed economic analysis based on current costs of energy and amount of energy anticipated from and costs associated with the tidal energy project conceptual design and scoped environmental issues. Utilizing circulation modeling, the Project Team identified two target sites with strong potential for robust tidal energy resources in Isanotski Strait and another nearer the City of False Pass. In addition, the Project Team completed a survey of the electrical infrastructure, which identified likely sites of interconnection and clarified required transmission distances from the tidal energy resources. Based on resource and electrical data, the Project Team developed a conceptual tidal energy project design utilizing ORPC’s TidGen® Power System. While the Project Team has not committed to ORPC technology for future development of a False Pass project, this conceptual design was critical to informing the Project’s economic analysis. The results showed that power from a tidal energy project could be provided to the City of False at a rate at or below the cost of diesel generated electricity and sold to commercial customers at rates competitive with current market rates, providing a stable, flat priced, environmentally sound alternative to the diesel generation currently utilized for energy in the community. The Project Team concluded that with additional grants and private investment a tidal energy project at False Pass is well-positioned to be the first tidal energy project to be developed in Alaska, and the first tidal energy project to be interconnected to an isolated micro grid in the world. A viable project will be a model for similar projects in coastal Alaska.

  6. 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.

  7. Volcano-Ice Interactions During Recent Eruptions of Aleutian Arc Volcanoes and Implications for Melt Water Generation

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.

    2013-12-01

    Recent eruptions in Alaska (Redoubt 2009; Pavlof 2007, 2013; Veniaminof 2013) all involved ice eruptive-product interactions that led to variable amounts of melt water generation. Production of melt water during explosive eruptions is the primary mechanism for lahar generation, which is a significant and sometimes-deadly hazard at snow and ice clad volcanoes. During the 2009 eruption of Redoubt Volcano, pyroclastic flows produced by explosive destruction of lava domes swept across and eroded glacier ice and generated large quantities of melt water that formed correspondingly large lahars (107-109 m3) in the Drift River valley north of the volcano. Three of the twenty lahars generated during the eruption were large enough to threaten an oil storage facility 40 km from the volcano. During eruptions of Pavlof Volcano in 2007 and 2013 spatter-fed lava flows and minor pyroclastic flows descended over snow and ice on the upper flanks of the volcano and produced some melt water that generated lahars in the associated drainages. These lahars were smaller than those associated with the 2009 eruption of Redoubt Volcano because the melt water generation mechanism was different. At Veniaminof Volcano, a low-level eruption beginning in June 2013 produced small lava flows that flowed passively over glacier ice and produced only limited amounts of melt water. Although melt pits surrounding the lava flows eventually developed, the rate of melt water production was gradual and no significant outflows of water occurred. These eruptions and comparison with past events highlight the various mechanisms for melt water production during eruptive activity at snow and ice clad Alaskan volcanoes. Dynamic emplacement of eruptive products over glacier ice that involves significant erosion of ice and snow leads to production of large volumes of melt water. Less dynamic, but still energetic interactions such as those that have occurred at Pavlof Volcano, produce smaller amounts of melt and correspondingly smaller volume lahars whose distribution is controlled in part by changes in the location of the summit vent. Effusive, subaerial eruptions at Veniaminof Volcano result in the smallest amount of meltwater production, mainly because the lava-ice interaction is not very dynamic and only a small proportion of the heat flux goes to melt ice.

  8. Late Holocene coastal stratigraphy of Sitkinak Island reveals Aleutian-Alaska megathrust earthquakes and tsunamis southwest of Kodiak Island

    NASA Astrophysics Data System (ADS)

    Nelson, A. R.; Briggs, R. W.; Kemp, A.; Haeussler, P. J.; Engelhart, S. E.; Dura, T.; Angster, S. J.; Bradley, L.

    2012-12-01

    Uncertainty in earthquake and tsunami prehistory of the Aleutian-Alaska megathrust westward of central Kodiak Island limit assessments of southern Alaska's earthquake hazard and forecasts of potentially damaging tsunamis along much of North America's west coast. Sitkinak Island, one of the Trinity Islands off the southwest tip of Kodiak Island, lies at the western end of the rupture zone of the 1964 Mw9.2 earthquake. Plafker reports that a rancher on the north coast of Sitkinak Island observed ~0.6 m of shoreline uplift immediately following the 1964 earthquake, and the island is now subsiding at about 3 mm/yr (PBO GPS). Although a high tsunami in 1788 caused the relocation of the first Russian settlement on southwestern Kodiak Island, the eastern extent of the megathrust rupture accompanying the tsunami is uncertain. Interpretation of GPS observations from the Shumagin Islands, 380 km southwest of Kodiak Island, suggests an entirely to partially creeping megathrust in that region. Here we report the first stratigraphic evidence of tsunami inundation and land-level change during prehistoric earthquakes west of central Kodiak Island. Beneath tidal and freshwater marshes around a lagoon on the south coast of Sitkinak Island, 27 cores and tidal outcrops reveal the deposits of four to six tsunamis in 2200 years and two to four abrupt changes in lithology that may correspond with coseismic uplift and subsidence over the past millennia. A 2- to 45-mm-thick bed of clean to peaty sand in sequences of tidal sediment and freshwater peat, identified in more than one-half the cores as far inland as 1.5 km, was probably deposited by the 1788 tsunami. A 14C age on Scirpus seeds, double 137Cs peaks at 2 cm and 7 cm depths (Chernobyl and 1963?), a consistent decline in 210Pb values, and our assumption of an exponential compaction rate for freshwater peat, point to a late 18th century age for the sand bed. Initial 14C ages suggest that two similar extensive sandy beds, identified in eight cores at higher tidal and freshwater sites, date from about 1.5 ka and 2.0 ka, respectively. A younger silty sand bed, <10 cm beneath the now-eroding low marsh around the lagoon, may record the 1964 tsunami. Correlations of two to three other sandy beds are too uncertain to infer their deposition by tsunamis. Stratigraphic contacts found only in cores and outcrops of the <0.8- to 1-ka tidal section fringing the lagoon may mark coseismic uplift (peat over tidal mud, sometimes with intervening sand) or subsidence (tidal mud over peat, sometimes with intervening sand). We collected samples of modern tidal foraminifera along three elevational transects for the baseline dataset needed to use fossil assemblages to measure the amount of uplift or subsidence recorded by contacts. Foraminiferal assemblages above and below one contact confirm rapid uplift a few hundred years before the 1788 tsunami, but cores are too few to correlate this contact with any of the sandy beds that we infer were deposited by tsunamis farther inland. These initial results demonstrate the promise of this previously unexplored island and similar sites for using stratigraphic evidence of sudden land-level changes and high tsunamis to map prehistoric ruptures of the Aleutian-Alaskan megathrust.

  9. Bering Sea and Aleutian Islands Management Area Pollock Seasons, 1991-2013 Updated 4/10/14

    E-print Network

    Page 1 Bering Sea and Aleutian Islands Management Area Pollock Seasons, 1991-2013 Updated 4/10/14 Area and 1991 1992 1993 1994 1995 Sector Season Open Close Days Open Close Days Open Close Days Open Close Days Open Close Days Inshore BS A Season 20-Jan 6-Mar 46 20-Jan 24-Mar 63 20-Jan 2-Mar 41 20-Jan 1

  10. The 1817 Eruption of Okmok Caldera, Umnak Island, Alaska: New Insights Into a Complex Historical Eruption in the Eastern Aleutians

    Microsoft Academic Search

    C. A. Neal; J. Beget; D. Grey; B. Wolfe

    2003-01-01

    Okmok is a 10-km-diameter, late-Holocene caldera on Umnak Island in the eastern Aleutians, 1400 km southwest of Anchorage. The most recent eruption in 1997 was strombolian in character, producing a basaltic-andesite lava flow within the caldera and localized ash fall. Since caldera-formation approximately 2050 14C yrs BP, however, more violent eruptions from vents within the caldera have impacted all flanks

  11. Living on Active Volcanoes - The Island of Hawaii

    NSDL National Science Digital Library

    Christina Heliker

    This United States Geological Survey (USGS) on-line publication highlights the volcanic hazards facing the people living on the Island of Hawaii. These hazards include lava flows, explosive eruptions, volcanic smog, earthquakes and tsunamis. This report discusses these hazards, the volcanoes of Mauna Loa and Kilauea, and the work of the Hawaiian Volcano Observatory to monitor and issue warnings to the people affected by these hazards.

  12. Science, policy, and stakeholders: developing a consensus science plan for Amchitka Island, Aleutians, Alaska.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Kosson, David S; Powers, Charles W; Friedlander, Barry; Eichelberger, John; Barnes, David; Duffy, Lawrence K; Jewett, Stephen C; Volz, Conrad D

    2005-05-01

    With the ending of the Cold War, the US Department of Energy is responsible for the remediation of radioactive waste and disposal of land no longer needed for nuclear material production or related national security missions. The task of characterizing the hazards and risks from radionuclides is necessary for assuring the protection of health of humans and the environment. This is a particularly daunting task for those sites that had underground testing of nuclear weapons, where the radioactive contamination is currently inaccessible. Herein we report on the development of a Science Plan to characterize the physical and biological marine environment around Amchitka Island in the Aleutian chain of Alaska, where three underground nuclear tests were conducted (1965-1971). Information on the ecology, geology, and current radionuclide levels in biota, water, and sediment is necessary for evaluating possible current contamination and to serve as a baseline for developing a plan to ensure human and ecosystem health in perpetuity. Other information required includes identifying the location of the salt water/fresh water interface where migration to the ocean might occur in the future and determining groundwater recharge balances, as well as assessing other physical/geological features of Amchitka near the test sites. The Science Plan is needed to address the confusing and conflicting information available to the public about radionuclide risks from underground nuclear blasts in the late 1960s and early 1970s, as well as the potential for volcanic or seismic activity to disrupt shot cavities or accelerate migration of radionuclides into the sea. Developing a Science Plan involved agreement among regulators and other stakeholders, assignment of the task to the Consortium for Risk Evaluation with Stakeholder Participation, and development of a consensus Science Plan that dealt with contentious scientific issues. Involvement of the regulators (State of Alaska), resource trustees (U S Fish and Wildlife Service), representatives of the Aleut and Pribilof Island communities, and other stakeholders was essential for plan development and approval, although this created tensions because of the different objectives of each group. The complicated process of developing a Science Plan involved iterations and interactions with multiple agencies and organizations, scientists in several disciplines, regulators, and the participation of Aleut people in their home communities, as well as the general public. The importance of including all parties in all phases of the development of the Science Plan was critical to its acceptance by a broad range of regulators, agencies, resource trustees, Aleutian/Pribilof communities, and other stakeholders. PMID:15886955

  13. Earthquake source parameters and stress distribution in the Adak Island region of the central Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    EkströM, GöRan; Engdahl, E. R.

    1989-11-01

    Source parameters have been systematically determined for all earthquakes with Mw?5 that occurred between 172°W and 179°W longitude in the Adak Island region of the central Aleutian Islands during 1977-March 1987. We relocate the events using a plate velocity model developed for the region and use two alternative methods of depth determination. The first method uses arrival times of direct and prominent reflected phases, primarily pwP. The second method uses broadband P wave displacement seismograms in an inversion for source depth. The analysis of these events provides a well-constrained data set for the study of stress release along an active subduction zone. Three earthquakes, which occurred seaward of the trench axis, are located just below the crust-mantle interface and show extension nearly perpendicular to the trench axis. Seven events occurred in the Wadati-Benioff zone. Sixty-four events are located in the main thrust zone, and, except for five unusual events, are characterized by thrust mechanisms with one nodal plane dipping north at a shallow angle. In cross section the thrust zone appears as a thin (10-15 km thickness) interplate region which extends from 15 to 50 km depth. A 10°-15° average discrepancy between observed slip vector azimuths and the predicted relative motion direction between the Pacific and North American plates exists for these events. The observed slip vectors are oriented more normal to the trench than is predicted by plate motions. Five earthquakes, which occurred as aftershocks to the May 7, 1986, earthquake (Mw = 8.0), in the crust of the overriding plate have strike-slip mechanisms consistent with right-lateral motion on arc-parallel fault planes. Observations of slip vectors along the whole Aleutian arc show a similar trend to that observed in the Adak Island region. The largest differences (˜30°) between observed and predicted slip azimuths occur around 175°E. We propose a model of plate interaction in which a portion of the along-arc motion occurs along a weak strike-slip shear zone in the upper plate, near the volcanic line. The slip azimuths in the main thrust zone fit this model well, if the amount of transcurrent slip occurring in the upper plate is ˜60% of the arc-parallel relative plate motion. A consequence of the model is along-arc extension of the overriding plate between the accretionary wedge and the volcanic line, especially in the western part of the Aleutian arc. Calculations based on a tectonic model by Geist et al. (1988) for the formation of arc summit basins through block rotation and translation, suggest that along-arc extension has been significant since late Miocene or early Pliocene.

  14. Mercury concentrations in breast feathers of three upper trophic level marine predators from the western Aleutian Islands, Alaska.

    PubMed

    Kaler, Robb S A; Kenney, Leah A; Bond, Alexander L; Eagles-Smith, Collin A

    2014-05-15

    Mercury (Hg) is a toxic element distributed globally through atmospheric transport. Agattu Island, located in the western Aleutian Islands, Alaska, has no history of point-sources of Hg contamination. We provide baseline levels of total mercury (THg) concentrations in breast feathers of three birds that breed on the island. Geometric mean THg concentrations in feathers of fork-tailed storm-petrels (Oceanodroma furcata; 6703 ± 1635, ng/g fresh weight [fw]) were higher than all other species, including snowy owl (Bubo scandiacus; 2105 ± 1631, ng/g fw), a raptor with a diet composed largely of storm-petrels at Agattu Island. There were no significant differences in mean THg concentrations of breast feathers among adult Kittlitz's murrelet (Brachyramphus brevirostris; 1658 ± 1276, ng/g fw) and chicks (1475 ± 671, ng/g fw) and snowy owls. The observed THg concentrations in fork-tailed storm-petrel feathers emphasizes the need for further study of Hg pollution in the western Aleutian Islands. PMID:24656750

  15. Near-field survey of the 1946 Aleutian tsunami on Unimak and Sanak Islands

    USGS Publications Warehouse

    Okal, E.A.; Plafker, G.; Synolakis, C.E.; Borrero, J.C.

    2003-01-01

    The 1946 Aleutian earthquake stands out among tsunamigenic events because it generated both very high run-up near the earthquake source region and a destructive trans-Pacific tsunami. We obtained new data on the distribution of its tsunami in the near field along south-facing coasts between Unimak Pass on the west and Sanak Island on the east by measuring the height of driftwood and beach materials that were deposited by the tsunami above the extreme storm tide level. Our data indicate that (1) the highest measured run-up, which is at the Scotch Cap lighthouse, was 42 m above tide level or about 37 m above present storm tide elevation; (2) run-up along the rugged coast from Scotch Cap for 12 km northwest to Sennett Point is 12-18 m, and for 30 km east of Scotch Cap to Cape Lutke it is 24-42 m; (3) run-up along the broad lowlands bordering Unimak Bight is 10-20 m, and in-undation is locally more than 2 km; (5) run-up diminishes to 8 m or less at the southeast corner of Unimak Island; (6) no evidence was found for run-up above present storm tides (about 4-5 m above MLLW) on the Ikatan Peninsula or areas along the coast to the west; and (7) run-up above storm tide level in the Sanak Island group is restricted to southwest-facing coasts of Sanak, Long, and Clifford Islands, where it is continuous and locally up to 24 m high. Generation of the tsunami by one or more major earthquake-triggered submarine landslides near the shelf edge south of Unimak Island seems to be the only viable mechanism to account for the data on wave arrival time, run-up heights, and distribution, as well as for unconfirmed anecdotal reports of local postquake increases in water depth and diminished bottom-fisheries productivity. A preliminary hydrodynamic simulation of the local tsunami propagation and run-up using a dipolar model of a possible landslide off Davidson Bank provides an acceptable fit to the characteristics of the distribution of local run-up, with a value at 34 m at the Scotch Cap lighthouse.

  16. Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands

    Microsoft Academic Search

    T. R. Walter; V. R. Troll; B. Cailleau; A. Belousov; H.-U. Schmincke; F. Amelung; P. v. d. Bogaard

    2005-01-01

    The relationship between rift zones and flank instability in ocean island volcanoes is often inferred but rarely documented. Our field data, aerial image analysis, and 40Ar\\/39Ar chronology from Anaga basaltic shield volcano on Tenerife, Canary Islands, support a rift zone—flank instability relationship. A single rift zone dominated the early stage of the Anaga edifice (~6–4.5 Ma). Destabilization of the northern sector

  17. AVIAN MORTALITY ASSOCIATED WITH A VOLCANIC GAS SEEP AT KISKA ISLAND, ALEUTIAN ISLANDS, ALASKA

    E-print Network

    Jones, Ian L.

    of avian mor- tality specifically associated with volcanic gases (Lobkov and Nikanorov 1981, Durand 2007 by CO2 or H2S emissions from geothermal vents at Sulphur Bay, Rotorua on New Zealand's North Island

  18. Adakitic volcanism in the eastern Aleutian arc: Petrology and geochemistry of Hayes volcano, Cook Inlet, Alaska

    NASA Astrophysics Data System (ADS)

    McHugh, K.; Hart, W. K.; Coombs, M. L.

    2012-12-01

    Located in south-central Alaska, 135 km northwest of Anchorage, Hayes volcano is responsible for the most widespread tephra fall deposit in the regional Holocene record (~3,500 BP). Hayes is bounded to the west by the Cook Inlet volcanoes (CIV; Mt. Spurr, Redoubt, Iliamna, and Augustine) and separated from the nearest volcanism to the east, Mount Drum of the Wrangell Volcanic Field (WVF), by a 400 km-wide volcanic gap. We report initial results of the first systematic geochemical and petrologic study of Hayes volcano. Hayes eruptive products are calc-alkaline dacites and rhyolites that have anomalous characteristics within the region. Major and trace element analyses reveal that the Hayes rhyolites are more silicic (~74 wt. % SiO2) than compositions observed in other CIV, and its dacitic products possess the distinctive geochemical signatures of adakitic magmas. Key aspects of the Hayes dacite geochemistry include: 16.03 - 17.54 wt. % Al2O3, 0.97 - 2.25 wt. % MgO, Sr/Y = 60 - 78, Yb = 0.9 - 1.2 ppm, Ba/La = 31 - 79. Such signatures are consistent with melting of a metamorphosed basaltic source that leaves behind a residue of garnet ± amphibole ± pyroxene via processes such as melting of a subducting oceanic slab or underplated mafic lower crust, rather than flux melting of the mantle wedge by dehydration of the down-going slab. Additionally, Hayes tephras display a distinctive mineralogy of biotite with amphibole in greater abundance than pyroxene, a characteristic not observed at other CIV. Furthermore, Hayes rhyolites and dacites exhibit little isotopic heterogeneity (87Sr/86Sr = 0.70384 - 0.70395, 206Pb/204Pb = 18.866 - 18.889) suggesting these lavas originate from the same source. Hayes volcano is approximately situated above the western margin of the subducting Yakutat terrane and where the dip of the Pacific slab beneath Cook Inlet shallows northward. Due to its position along the margin of the subducting Yakutat terrane, it is plausible that Hayes magmas are the result of partial melting of this slab where thermal erosion and weakening of the crust occurs along the Pacific plate-Yakutat terrane transition. Additionally, flat slab subduction may be responsible for producing adakitic magmas by equilibration of the hydrous slab with ambient mantle temperatures. In contrast, it is possible that the adakitic signature at Hayes is from underplated mafic lower crust that melted as the result of pooling mantle melt at depth. Two volcanoes within the WVF, Mt. Drum and Mt. Churchill, are adakitic with an abundance of biotite and amphibole similar to Hayes volcano and have been suggested to have slab melt origins. Mt. Drum lavas have less radiogenic 87Sr/86Sr but overlapping 206Pb/204Pb signatures while Mt. Churchill, which approximately overlies the eastern edge of the Yakutat terrane, has similar 87Sr/86Sr compositions, but more radiogenic 206Pb/204Pb than Hayes. Mt. Spurr, the nearest CIV to Hayes volcano (90 km south), does not share its adakitic signature but exhibits overlapping, more heterogeneous isotopic compositions. Thus, understanding the petrogenetic history of Hayes volcano is essential not only to explain the development of an adakitic volcanic system but how this relates to regional, arc-wide volcanism.

  19. Surname distributions and Y-chromosome markers in the Aleutian Islands

    E-print Network

    Graf, Orion Mark; Zlojutro, Mark; Rubicz, Rohina C.; Crawford, Michael H.

    2010-01-01

    We examine surname distribution, origin, and association with Y-chromosome haplogroups in native communities from the Aleutian archipelago. The underlying hypothesis is that surnames and Y-chromosome haplogroups should be associated because both...

  20. New glass sponges (Porifera: Hexactinellida) from deep waters of the central Aleutian Islands, Alaska.

    PubMed

    Reiswig, Henry M; Stone, Robert P

    2013-01-01

    Hexactinellida from deep-water communities of the central Aleutian Islands, Alaska, are described. They were mostly collected by the remotely operated vehicle 'Jason II' from 494–2311 m depths during a 2004 RV 'Roger Revelle' expedition, but one shallow-water species collected with a shrimp trawl from 155 m in the same area is included. The excellent condition of the ROV-collected specimens enabled valuable redescription of some species previously known only from badly damaged specimens. New taxa include one new genus and eight new species in five families. Farreidae consist of two new species, Farrea aleutiana and F. aspondyla. Euretidae consists of only Pinulasma fistulosum n. gen., n. sp. Tretodictyidae include only Tretodictyum amchitkensis n. sp. Euplectellidae consists of only the widespread species Regadrella okinoseana Ijima, reported here over 3,700 km from its closest previously known occurrence. The most diverse family, Rossellidae, consists of Aulosaccus ijimai (Schulze), Aulosaccus schulzei Ijima, Bathydorus sp. (young stage not determinable to species), Caulophacus (Caulophacus) adakensis n. sp., Acanthascus koltuni n. sp., Staurocalyptus psilosus n. sp., Staurocalyptus tylotus n. sp. and Rhabdocalyptus mirabilis Schulze. We present argument for reinstatement of the abolished rossellid subfamily Acanthascinae and return of the subgenera ?Staurocalyptus Ijima and Rhabdocalyptus Schulze to their previous generic status. These fauna provides important complexity to the hard substrate communities that likely serve as nursery areas for the young stages of commercially important fish and crab species, refuge from predation for both young and adult stages, and also as a focal source of prey for juvenile and adult stages of those same species. PMID:25325089

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  2. Magma storage conditions of the last eruption of Teide volcano (Canary Islands, Spain)

    E-print Network

    Paris-Sud XI, Université de

    11 Magma storage conditions of the last eruption of Teide volcano (Canary Islands, Spain) Andújar of the phonolitic magma responsible for the last eruption (about 1150 yr B.P.) of Teide volcano. The Lavas Negras storage depth at about 5 ± 1 km below current summit of Teide volcano. Given that the island has

  3. Radionuclide concentrations in benthic invertebrates from Amchitka and Kiska Islands in the Aleutian Chain, Alaska.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Jewett, Stephen C

    2007-05-01

    Concentrations of 13 radionuclides (137Cs, 129I, 60Co, 152Eu, 90Sr, 99Tc, 241Am, 238Pu, 239,249Pu, 234U, 235U, 236U, 238U) were examined in seven species of invertebrates from Amchitka and Kiska Islands, in the Aleutian Chain of Alaska, using gamma spectroscopy, inductively coupled plasma mass spectroscopy, and alpha spectroscopy. Amchitka Island was the site of three underground nuclear test (1965-1971), and we tested the null hypotheses that there were no differences in radionuclide concentrations between Amchitka and the reference site (Kiska) and there were no differences among species. The only radionuclides where composite samples were above the Minimum Detectable Activity (MDA) were 137Cs, 241Am, 239,249Pu, 234U, 235U, 236U, and 238U. Green sea urchin (Strongylocentrotus polyacanthus), giant chiton (Cryptochiton stelleri), plate limpets (Tectura scutum) and giant Pacific octopus (Enteroctopus dofleini) were only tested for 137Cs; octopus was the only species with detectable levels of 137Cs (0.262 +/- 0.029 Bq/kg, wet weight). Only rock jingle (Pododesmus macroschisma), blue mussel (Mytilus trossulus) and horse mussel (Modiolus modiolus) were analyzed for the actinides. There were no interspecific differences in 241Am and 239,240Pu, and almost no samples above the MDA for 238Pu and 236U. Horse mussels had significantly higher concentrations of 234U (0.844 +/- 0.804 Bq/kg) and 238U (0.730 +/- 0.646) than the other species (both isotopes are naturally occurring). There were no differences in actinide concentrations between Amchitka and Kiska. In general, radionuclides in invertebrates from Amchitka were similar to those from uncontaminated sites in the Northern Hemisphere, and below those from the contaminated Irish Sea. There is a clear research need for authors to report the concentrations of radionuclides by species, rather than simply as 'shellfish', for comparative purposes in determining geographical patterns, understanding possible effects, and for estimating risk to humans from consuming different biota. PMID:17057992

  4. Volcaniclastic sedimentation on the submarine slopes of a basaltic hotspot volcano: Piton de la Fournaise volcano (La Runion Island, Indian Ocean)

    E-print Network

    Paris-Sud XI, Université de

    1 Volcaniclastic sedimentation on the submarine slopes of a basaltic hotspot volcano: Piton de la Fournaise volcano (La Réunion Island, Indian Ocean) Francky Saint-Ange a,b,d,*, Patrick Bachèlery c hotspot volcanoes as exemplified by the Piton de la Fournaise volcano (La Réunion Island). The facies

  5. Strong Crustal Earthquakes in Central Aleutian Islands in 2006-2008: Implications for the Block Rotation Model

    NASA Astrophysics Data System (ADS)

    Kozyreva, N. P.; Ruppert, N. A.; Hansen, R. A.

    2008-12-01

    Between 2006 and 2008 six strong crustal earthquakes occurred in central and western Aleutian Islands. The series started with a M6.5 event on June 14, 2006 that occurred immediately west of Kiska Island and had a M6.0 aftershock. Two weeks later a M6.2 event occurred near Buldir Island. On April 15 and 16, 2008 a M6.4 and M6.6 earthquakes occurred in the Amchitka Pass area and on May 2, 2008 a M6.6 earthquake occurred between the Kanaga and Tanaga Islands. The events are located along a 450 km long segment of the Aleutian arc and all have strike-slip faulting mechanisms with varying orientations of the focal planes. The Alaska Earthquake Information Center reported hundreds of aftershocks for each event. Due to the seismic network limitations, however, the event locations are poorly constrained and the fault planes can not be easily determined. Geist et al. (1988) proposed a block rotation model for the central and western Aleutians. Five blocks of various sizes have been identified based on geomorphic evidence. Boundaries between the blocks were delineated based on the submarine fault-controlled canyons. Northern boundaries were defined as the southern edge of the corresponding summit basins, which were formed as result of rotation of the blocks. Southern boundaries were prescribed along the seaward edge of the arc massif. The block boundaries were meant to delineate regions of cohesive movement. They are bounded by zones that are significantly disrupted by normal and strike-slip faults. The 2006-2008 earthquakes are located either on or north of the delineated northern boundaries of the Buldir, Rat and Delarof blocks. A search of the Global CMT catalog produced a handful of crustal strike-slip events in the region. The most notable are the earthquakes that occurred after the great megathrust events in the region, such as a Ms7.2 event in 1966 that followed the M8.7 1965 Rat Islands earthquake and a series of strong crustal shocks (up to M6.6) near Atka Island following the M8.0 1986 Adak earthquake. Most of the recorded crustal strike-slip events are concentrated near the block boundaries. We use waveform cross-correlation and double-difference relocations to identify aftershock distribution and determine preferred fault planes of the 2006-2008 earthquakes to identify how these events characterize the crustal block model.

  6. 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

    2014-08-01

    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.

  7. Phonolitic Diatremes within the Dunedin Volcano, South Island, New Zealand

    Microsoft Academic Search

    RICHARD C. PRICE; ALAN F. COOPER; JON D. WOODHEAD; IAN CARTWRIGHT

    2003-01-01

    The Port Chalmers Breccia is a vent-filling, clastic volcanic unit exposed within the Miocene Dunedin Volcano of South Island, New Zealand. Clasts (up to in excess of 1m but generally 520cm) are supported in ash and fine lapilli of phonolitic (ne-benmoreite or tephro-phonolite) composition and the dominant clast type (55 to almost 100%) is also phonolitic. Less abundant lithologies include

  8. Optical dating of hydromagmatic volcanoes on the southwestern coast of Jeju Island, Korea

    Microsoft Academic Search

    C. S. Cheong; J. H. Choi; Y. K. Sohn; J. C. Kim; G. Y. Jeong

    2007-01-01

    Jeju Island, the largest Quaternary volcanic island in Korea, has formed mostly since the early Pleistocene, but its latest chronology of volcanism and sedimentation is still poorly constrained. Here we report optically stimulated luminescence (OSL) ages for two hydromagmatic volcanoes on the southwestern coast of Jeju Island, i.e., the Songaksan and Suwolbong tuff rings. The basaltic tuffs of these volcanoes

  9. Electromagnetic Imaging and Seismotectonics of Mud Volcanoes in Andaman Islands

    NASA Astrophysics Data System (ADS)

    Subba Rao, Pbv; Singh, Ak

    2012-07-01

    Stress perturbations from large earthquakes are capable of causing significant changes in different physical properties of the subsurface such as electrical conductivity, temperature and rheoloy. The Mw 9.0 Sumatra earthquake on December 26, 2004 has stimulated mud volcanic activity on the Island of Bartang in the Middle Andaman Islands and at Diglipur in North Andamans. Relation between large earthquakes and mud volcano eruptions are common but the exact accelerating / triggering mechanisms are little understood (Mellors et al., 2007, JGR, 112, B04304). Here, we examined Geomagnetic Depth Sounding (GDS) and Long period MagnetoTelluric (LMT) data sets that image the electrical conductivity and variations associated with the subsurface stress environment. Two profiles in middle and north Andamans brings out localized anomalies associated with mud volcano. The possible cause for this electrical conductivity anomaly could be due to presence of fluids along a fractured fault/fissure. Continous monitoring of these mud volcanoes will facilitate inferring the accumulation/built up of the stress in the study area. In the present study, we discuss and highlight the significance of EM imaging of electrical conductivity (by GDS and AMT/MT/LMT) as a marker of fluid distribution and its influence on the reactivation of rheological asperity in triggering seismic activity in Andaman Island.

  10. Scotch Cap Light Station on Unimak Island in the Alaskan Aleutian chain after destruction by the Tsunami of April1, 1946. The Tsunami claimed the lives of

    E-print Network

    on Unimak Island in the Alaskan Aleutian chain after destruction by the Tsunami of April1, 1946. The Tsunami.) #12;TSUNAMI RESEARCH OPPORTUNITIES An Assessment and Comprehensive Guide National Science Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Figure 1 -Tsunami Data (1876-1976) .. . . . . .. .. .. .. .. . .. . .. 3 Table I - Major Tsunami

  11. Auklet (Charadriiformes: Alcidae, Aethia spp.) chick meals from the Aleutian Islands, Alaska, have a very low incidence of plastic marine debris

    E-print Network

    Jones, Ian L.

    t i c l e i n f o Keywords: Plastic Marine debris North Pacific Ocean Auklet Aethia Aleutian Islands in the world's oceans (Moore, 2008). This anthropogenic pollution may be mistaken for food by foraging seabirds; Ryan, 1988). In the North Pacific Ocean, incidences of plastic ingestion in a wide variety of seabirds

  12. Seismic monitoring at Deception Island volcano (Antarctica): Recent advances

    NASA Astrophysics Data System (ADS)

    Carmona, E.; Almendros, J.; Martín, R.; Cortés, G.; Alguacil, G.; Moreno, J.; Martín, B.; Martos, A.; Serrano, I.; Stich, D.; Ibáñez, J. M.

    2012-04-01

    Deception Island (South Shetland Island, Antarctica) is an active volcano with recent eruptions (e.g. 1967, 1969 and 1970). It is also among the Antarctic sites most visited by tourists. Besides, there are currently two scientific bases operating during the austral summers, usually from late November to early March. For these reasons it is necessary to deploy a volcano monitoring system as complete as possible, designed specifically to endure the extreme conditions of the volcanic environment and the Antarctic climate. The Instituto Andaluz de Geofísica of University of Granada, Spain (IAG-UGR) performs seismic monitoring on Deception Island since 1994 during austral summer surveys. The seismicity basically includes volcano-tectonic earthquakes, long-period events and volcanic tremor, among other signals. The level of seismicity is moderate, except for a seismo-volcanic crisis in 1999. The seismic monitoring system has evolved during these years, following the trends of the technological developments and software improvements. Recent advances have been mainly focused on: (1) the improvement of the seismic network introducing broadband stations and 24-bit data acquisition systems; (2) the development of a short-period seismic array, with a 12-channel, 24-bit data acquisition system; (3) the implementation of wireless data transmission from the network stations and also from the seismic array to a recording center, allowing for real-time monitoring; (4) the efficiency of the power supply systems and the monitoring of the battery levels and power consumption; (5) the optimization of data analysis procedures, including database management, automated event recognition tools for the identification and classification of seismo-volcanic signals, and apparent slowness vector estimates using seismic array data; (6) the deployment of permanent seismic stations and the transmission of data during the winter using a satellite connection. A single permanent station is operating at Deception Island since 2008. In the current survey we collaborate with the Spanish Army to add another permanent station that will be able to send to the IAG-UGR seismic information about the activity of the volcano during the winter, using a communications satellite (SPAINSAT). These advances simplify the field work and the data acquisition procedures, and allow us to obtain high-quality seismic data in real-time. These improvements have a very important significance for a better and faster interpretation of the seismo-volcanic activity and assessment of the volcanic hazards at Deception Island volcano.

  13. Evolution of a Quaternary peralkaline volcano: Mayor Island, New Zealand

    USGS Publications Warehouse

    Houghton, B.F.; Weaver, S.D.; Wilson, C.J.N.; Lanphere, M.A.

    1992-01-01

    Mayor Island is a Holocene pantelleritic volcano showing a wide range of dispersive power and eruptive intensity despite a very limited range in magma composition of only 2% SiO2. The primary controls on this range appear to have been the magmatic gas content on eruption and a varying involvement of basaltic magma, rather than major-element chemistry of the rhyolites. The ca. 130 ka subaerial history of the volcano contains portions of three geochemical cycles with abrupt changes in trace-element chemistry following episodes of caldera collapse. The uniform major-element chemistry of the magma may relate to a fine balance between rates of eruption and supply and the higher density of the more evolved (Ferich) magmas which could be tapped only after caldera-forming events had removed significant volumes of less evolved but lighter magma. ?? 1992.

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

    E-print Network

    Chadwick, Bill

    The submarine flanks of Anatahan Volcano, commonwealth of the Northern Mariana Islands William W flanks of Anatahan volcano were surveyed comprehensively for the first time in 2003 and 2004 that 67% of the volcano's submarine flanks are covered with volcaniclastic debris and 26% is lava flows

  15. Volcanoes

    NSDL National Science Digital Library

    Scott Johnson

    This resource provides general information about volcanoes. It illustrates the growth of a volcano, using Paricutin and Mt. St. Helens as examples of an active volcano and a lava dome. The terms extinct and dormant are also discussed. This site provides an explanation of why and how volcanoes form, zones of subduction, mid-ocean ridges, and hot spots. Deadly dangers associated with eruptions are discussed as is the use of a tiltmeter for prediction. The content center lesson describes a possible connection between the lost continent of Atlantis and the island of Santorini. Dissolved gasses in magma and the creation of a lava dome are both demonstrated in the hands-on section.

  16. Aleutian terranes from Nd isotopes

    NASA Technical Reports Server (NTRS)

    Kay, R. W.; Kay, S. M.; Rubenstone, J. L.

    1986-01-01

    Nd isotope ratios substantiate the identification of oceanic crustal terranes within the continental crustal basement of the Aleutian island arc. The oceanic terranes are exposed in the westernmost Aleutians, but to the east, they are completely buried by isotopically distinct arc-volcanic rocks. Analogous oceanic terranes may be important components of the terrane collages that comprise the continents.

  17. Evaluation of landslide susceptibility of Sete Cidades Volcano (S. Miguel Island, Azores)

    Microsoft Academic Search

    A. Gomes; J. L. Gaspar; C. Goulart; G. Queiroz

    2005-01-01

    Sete Cidades is an active central volcano with a summit caldera located in the westernmost part of S. Miguel Island (Azores). Since the settlement of the Island, in the 15th century, many landslide events occurred in this volcano, causing extensive damages in buildings and infrastructures. The study of historical records and the observation of new occurrences showed that landslides in

  18. Hydrochemical fluxes from Baransky volcano, Iturup, Kuril Islands

    NASA Astrophysics Data System (ADS)

    Chelnokov, George; Zharkov, Rafael; Bragin, Ivan; Kharitonova, Natalia

    2014-05-01

    The Sernaya River and its tributary the Kipyashaya River are the only rivers that drain all thermal waters coming down the Baransky volcano (Iturup, the Kuril Islands). Hydrological parameters and a chemical composition relating to these rivers and all inflow streams coming from the volcano were measured from August to October 2013. The main aims of this investigation were to develop a data baseline for the catchment of the Sernaya River in order to monitor the Baransky volcano, to estimate total discharge of solute elements and finally to identify thermal groundwater inflow. Since the Kipyashaya River and the Sernaya River receive all water streams coming along the south-west and south flanks of the Baransky volcano within approximately 10 kilometers we can suggest that the whole thermal discharge runs into the Kipyashaya River. Thus a frequent sampling of the rivers presents the best way to monitor the volcano as they comprise a mix of all thermal waters from the Baransky volcano. The Sernaia River, at the end of its course along the flanks of the Baransky volcano, has a total flux of 12 m³/s ± 1%. Multiplication of the discharge by the concentration in main ions of the river at this point yields an aggregate flux of ~130 tons/day ± 10%. This flux performs the dissolution flux as a result of rocks dissolution beneath the active crater and in the aquifer of the Kipyashaya River. Cl total discharge was estimated at ~33 tons/day ± 10%, SO4 ~67 tons/day ± 10%, and total cation discharge ~28 tons/day ± 10%. The Kipyashaya River brings in to the Sernaya River 15 tons/day ± 10% of Cl, ~30 tons/day ± 10% of SO4, and ~3,5 tons/day ± 10% cations average. Several thermal springs with low water discharge are located on the right waterside of the Sernaya River 100 m up and down from the Kipyashaya River influx. These thermal springs with Cl discharge ~ 5g/s have significant concentrations of Ca due to water-rock interaction with basement rocks. The way of sampling streams at the end of their course, just before confluence with the Sernaia River, provides more representative chemical composition of the Baransky volcano waters than a punctual sampling of springs and indicates the existing thermal groundwater inflow. It is argued that a renewal in the activity of the Baransky volcano is a result of the changes in chemical ratios and Cl discharge. Studying the network of the Sernaya River presents one of the best ways of detection such pre-eruptive periods. The work was supported by RFBR grants 13-05-00544A, 14-05-00243, 14-05-00171 and FEB RAS grant 12-III-A-08-161.

  19. Remote sensing for active volcano monitoring in Barren Island, India

    SciTech Connect

    Bhattacharya, A.; Reddy, C.S.S.; Srivastav, S.K. (National Remote Sensing Agency, Hyderabad (India))

    1993-08-01

    The Barren Island Volcano, situated in the Andaman Sea of the Bay of Bengal, erupted recently (March, 1991) after a prolonged period of quiescence of about 188 years. This resumed activity coincides with similar outbreaks in the Philippines and Japan, which are located in an identical tectonic environment. This study addresses (1) remote sensing temporal monitoring of the volcanic activity, (2) detecting hot lava and measuring its pixel-integrated and subpixel temperatures, and (3) the importance of SWIR bands for high temperature volcanic feature detection. Seven sets of TM data acquired continuously from 3 March 1991 to 8 July 1991 have been analyzed. It is concluded that detectable pre-eruption warming took place around 25 March 1991 and volcanic activity started on 1 April 1991. It is observed that high temperature features, such as an erupting volcano, can register emitted thermal radiance in SWIR bands. Calculation of pixel-integrated and sub-pixel temperatures related to volcanic vents has been made, using the dual-band method. 6 refs.

  20. Numerical modeling of tsunami waves generated by the flank collapse of the Cumbre Vieja Volcano (La Palma, Canary Islands)

    E-print Network

    Kirby, James T.

    Numerical modeling of tsunami waves generated by the flank collapse of the Cumbre Vieja Volcano (La of the Cumbre Vieja Volcano (CVV; La Palma, Canary Island, Spain) through numerical simulations performed in two generated by the flank collapse of the Cumbre Vieja Volcano (La Palma, Canary Islands): Tsunami source

  1. Evolution and geochemistry of the Tertiary calc-alkaline plutons in the Adak Island region of the central Aleutian oceanic island arc

    NASA Astrophysics Data System (ADS)

    Kay, Suzanne; Citron, Gary P.; Kay, Robert W.; Jicha, Brian; Tibbetts, Ashley

    2014-05-01

    Calc-alkaline plutons are major crustal building blocks of continental margin mountain belts like the Mesozoic to Tertiary Andes and the Sierra Nevada, but are rare in oceanic island arcs. Some of the most calc-alkaline I-type island arc plutons are in the Central Aleutians with the most extreme signatures, as indicated by FeO/MgO ratios of < ~2 at 48-70% wt. % SiO2, in the ~10 km wide Oligocene Hidden Bay pluton on southern Adak Island and the 10 km wide Miocene Kagalaska pluton to the north on eastern Adak and the adjacent Kagalaska Island. Although small compared to most continental plutons, similarities in intrusive units, mineralogy and chemistry suggest common formation processes. The Aleutian calc-alkaline plutonic rocks mainly differ from continental plutons in having more oceanic like isotopic (87Sr/86Sr = 0.703-0.7033; Epsilon Nd = 9-7.8) and LIL (e.g., higher K/Rb) ratios. The Adak region plutons differ from Tertiary plutons on Unalaska Island further east in being more K-rich and in having a more oxidized and lower-temperature mineralogy. From a regional perspective, the Adak area plutons intrude Eocene/Oligocene Finger Bay Formation mafic volcanic and sedimentary rocks and postdate the small ~38 Ma tholeiitic Finger Bay pluton. The chemistry of these older magmatic rocks is basically similar to that of young Central Aleutian magmatic rocks with boninites and arc tholeiitic magmas seemingly being absent. The formation of the calc-alkaline plutons seems to require a sufficient crustal thickness, fluid concentration and contractional stress such that magma chambers can stabilize significant amounts of pargasitic hornblende. Seismic receiver function analyses (Janiszewski et al., 2013) indicate the modern Adak crust is ~ 37 km thick. Existing and new hornblende, plagioclase and biotite Ar/Ar ages from 16 Hidden Bay pluton and Gannet Lake stock gabbro, porphyritic diorite, diorite, granodiorite, leucogranodiorite and aplite samples range from 34.6 to 30.9 Ma and indicate an ~ 4 Ma intrusion history. Biotite Ar/Ar ages for Kagalaska gabbro and granodiorite samples range from 14.7 to 13.9 Ma. The new ages are consistent with the plutons being related to several eruptive centers and forming during the waning stages of volcanism as the magmatic arc front was displaced to the north, possibly in response to accelerated periods of forearc subduction erosion. The gabbroic to leucogranodioritic units evolved in the lower to mid-crust with more silicic magmas rising buoyantly to higher levels where final crystallization and segregation of aplites occurred. Most gabbro and all mafic diorite units are largely crystal cumulates; one gabbro approaches the melt composition of a high Al basalt. The volumetrically dominant silicic diorites and granodiorites (58-63% SiO2) show the most zoning in their mineral phases and approach melt compositions. The leucogranodiorite (67-70% SiO2)unit was the last to crystallize. The silicic units are considered to be deep-crustal differentiates of high-Al basalt magmas, although partial melting of older magmatic rocks may play a role. Mafic dikes in the pluton represent the basic magmas under the dying arc front as the front moved northward.

  2. Steller Sea Lion Protection Measures for Groundfish Fisheries in the Bering Sea and Aleutian Islands

    E-print Network

    Islands Management Area Draft Environmental Impact Statement/Regulatory Impact Review/Initial Regulatory Islands Management Area Draft Environmental Impact Statement/Regulatory Impact Review/Initial Regulatory Department of Fish and Game Abstract: This environmental impact statement/regulatory impact review

  3. A new model for the formation of linear rift zones on oceanic island volcanoes

    Microsoft Academic Search

    A. Kluegel; T. R. Walter

    2003-01-01

    Oceanic island volcanoes commonly contain rift zones along which eruptive centers and parallel dike complexes are concentrated. Formation and orientation of rifts often remain enigmatic, however. Tectonic lineaments and regional zones of weakness facilitating magma ascent may be one reason of rift evolution, e.g. Sao Jorge (Azores) or Iceland. Alternatively, gravity tectonics of a volcano may cause formation of dike

  4. Economic and engineering considerations for geothermal development in the Makushin Volcano Region of Unalaska Island, Alaska

    SciTech Connect

    Reeder, J.W.; Economides, M.J.; Markle, D.R.

    1982-10-01

    Large vapor-dominated hydrothermal reservoirs are suspected to exist in the region marked by fumarole fields on the southeast flank of Makushin Volcano on Unalaska Island, Alaska. In this paper, economic and engineering considerations with respect to potential hydrothermal development in the Makushin Volcano region are presented.

  5. A submarine canyon as the cause of a mud volcano Liuchieuyu Island in Taiwan

    E-print Network

    Lin, Andrew Tien-Shun

    A submarine canyon as the cause of a mud volcano Ð Liuchieuyu Island in Taiwan J. Chowa,*, J, we also discuss the relationship between a nearby submarine canyon (Kaoping Submarine Canyon¯ection; Submarine canyon; Mud volcano 1. Introduction In the early Pliocene, the paleoenvironment of the offshore

  6. Final Report: Weatherization and Energy Conservation Education and Home Energy and Safety Review in the Aleutian Islands

    SciTech Connect

    Bruce Wright

    2011-08-30

    Aleutian/Pribilof Islands Association, Inc. (APIA) hired three part-time local community members that desire to be Energy Technicians. The energy technicians were trained in methods of weatherization assistance, energy conservation and home safety. They developed a listing of homes in the region that required weatherization, and conducted on-site weatherization and energy conservation education and a home energy and safety reviews in the communities of Akutan, False Pass, King Cove and Nelson Lagoon. Priority was given to these smaller communities as they tend to have the residences most in need of weatherization and energy conservation measures. Local residents were trained to provide all three aspects of the project: weatherization, energy conservation education and a home energy and safety review. If the total energy saved by installing these products is a 25% reduction (electrical and heating, both of which are usually produced by combustion of diesel fuel), and the average Alaska home produces 32,000 pounds of CO2 each year, so we have saved about: 66 homes x 16 tons of CO2 each year x .25 = 264 tons of CO2 each year.

  7. HLA genes of Aleutian Islanders living between Alaska (USA) and Kamchatka (Russia) suggest a possible southern Siberia origin.

    PubMed

    Moscoso, Juan; Crawford, Michael H; Vicario, Jose L; Zlojutro, Mark; Serrano-Vela, Juan I; Reguera, Raquel; Arnaiz-Villena, Antonio

    2008-02-01

    Aleuts HLA profile has been compared with that of neighboring and worldwide populations. Thirteen thousand one hundred and sixty-four chromosomes have been used for this study. Computer programs have obtained HLA allele frequencies, genetic distances between populations, NJ relatedness dendrograms, correspondence analysis and most frequent HLA extended haplotypes. Aleuts have inhabited Aleutian Islands since about 9000 years BP according to fossil and genetic (mtDNA) records. They are genetically different to Eskimo, Amerindian and Na-Dene speakers according to their HLA profile; this correlates with cultural and anthropological Aleut distinctiveness. No typical Amerindian HLA alleles have been found in a significant frequency. Their HLA relatedness to Saami (or Lapps, northern Scandinavians), Finns and Pomors (North-West Russia) indicates an ancient possible origin from the Baikal Lake Area (southern Siberia) around the present day Buryat peopling area; other origins are not discarded. Aleuts characteristic HLA profile may influence future transplantation programs in the region and be useful to study diseases linked to HLA epidemiology. PMID:17825912

  8. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Islands Statistical and Reporting Areas ...Description 300 Russian waters. Those waters inside the Russian 200 mile limit as...Southern Part) and NOAA chart INT 814...the limits of the EEZ and Russian economic...

  9. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Islands Statistical and Reporting Areas ...Description 300 Russian waters. Those waters inside the Russian 200 mile limit as...Southern Part) and NOAA chart INT 814...the limits of the EEZ and Russian economic...

  10. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Islands Statistical and Reporting Areas ...Description 300 Russian waters. Those waters inside the Russian 200 mile limit as...Southern Part) and NOAA chart INT 814...the limits of the EEZ and Russian economic...

  11. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Islands Statistical and Reporting Areas ...Description 300 Russian waters. Those waters inside the Russian 200 mile limit as...Southern Part) and NOAA chart INT 814...the limits of the EEZ and Russian economic...

  12. Submarine growth and internal structure of ocean island volcanoes based on submarine observations of Mauna Loa volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Garcia, Michael O.; Davis, Michael G.

    2001-02-01

    A recent model for the submarine growth of Hawaiian volcanoes indicates that these volcanoes are composed mainly of fragmental lava debris formed as lavas enter the ocean. This model has major implications for locating earthquake hypocenters and for the landslide hazard potential of these and other ocean island volcanoes. Observations from submersible dives and analyses of volcanic glasses collected from the western submarine flank of Mauna Loa indicate that subaerially erupted pillow lavas are abundant at depths of 950 to 1900 m below sea level. Fragmental lava is an important component of ocean island volcanoes, as witnessed during the most recent eruption of Kilauea volcano, but probably is the dominant lithology only in the upper 1 km of the submarine section. A submarine dike complex was discovered 17 km west of the assumed axis of Mauna Loa's southwest rift, which indicates that its intrusive complex is much broader than previously suspected (˜20 km vs. ˜8 km). The great width of this dike complex may be a consequence of crustal unloading following the South Kona landslide or a normal feature of Hawaiian rift zones that was previously unrecognized.

  13. Steller Sea Lion Protection Measures for Groundfish Fisheries in the Bering Sea and Aleutian Islands

    E-print Network

    Islands Management Area Draft Environmental Impact Statement/Regulatory Impact Review/Initial Regulatory Area Draft Environmental Impact Statement/Regulatory Impact Review/Initial Regulatory Flexibility of Fish and Game Abstract: This environmental impact statement/regulatory impact review/initial regulatory

  14. On the absence of InSAR-detected volcano deformation spanning the 1995–1996 and 1999 eruptions of Shishaldin Volcano, Alaska

    Microsoft Academic Search

    S. C. Moran; O. Kwoun; T. Masterlark; Z. Lu

    2006-01-01

    Shishaldin Volcano, a large, frequently active basaltic-andesite volcano located on Unimak Island in the Aleutian Arc of Alaska, had a minor eruption in 1995–1996 and a VEI 3 sub-Plinian basaltic eruption in 1999. We used 21 synthetic aperture radar images acquired by ERS-1, ERS-2, JERS-1, and RADARSAT-1 satellites to construct 12 coherent interferograms that span most of the 1993–2003 time

  15. Levels of Polychlorinated Biphenyls (PCBs) and Three Organochlorine Pesticides in Fish from the Aleutian Islands of Alaska

    PubMed Central

    Hardell, Sara; Tilander, Hanna; Welfinger-Smith, Gretchen; Burger, Joanna; Carpenter, David O.

    2010-01-01

    Background Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and chlorinated pesticides, have been shown to have many adverse human health effects. These contaminants therefore may pose a risk to Alaska Natives that follow a traditional diet high in marine mammals and fish, in which POPs bioaccumulate. Methods and Findings This study examined the levels of PCBs and three pesticides [p, p?-DDE, mirex, and hexachlorobenzene (HCB)] in muscle tissue from nine fish species from several locations around the Aleutian Islands of Alaska. The highest median PCB level was found in rock sole (Lepidopsetta bilineata, 285 ppb, wet weight), while the lowest level was found in rock greenling (Hexagrammos lagocephalus, 104 ppb, wet weight). Lipid adjusted PCB values were also calculated and significant interspecies differences were found. Again, rock sole had the highest level (68,536 ppb, lipid weight). Concerning the PCB congener patterns, the more highly chlorinated congeners were most common as would be expected due to their greater persistence. Among the pesticides, p, p?-DDE generally dominated, and the highest level was found in sockeye salmon (Oncorhynchus nerka, 6.9 ppb, wet weight). The methodology developed by U.S. Environmental Protection Agency (USEPA) was used to calculate risk-based consumption limits for the analyzed fish species. For cancer health endpoints for PCBs, all species would trigger strict advisories of between two and six meals per year, depending upon species. For noncancer effects by PCBs, advisories of between seven and twenty-two meals per year were triggered. None of the pesticides triggered consumption limits. Conclusion The fish analyzed, mainly from Adak, contain significant concentrations of POPs, in particular PCBs, which raises the question whether these fish are safe to eat, particularly for sensitive populations. However when assessing any risk of the traditional diet, one must also consider the many health and cultural benefits from eating fish. PMID:20811633

  16. A model for selecting bioindicators to monitor radionuclide concentrations using Amchitka Island in the Aleutians as a case study

    SciTech Connect

    Burger, Joanna [Division of Life Sciences, Environmental and Occupational Health Sciences Institute, and Consortium for Risk Evaluation with Stakeholder Participation, Rutgers University, Piscataway, NJ (United States)], E-mail: burger@biology.rutgers.edu

    2007-11-15

    World War II and the Cold War have left the Unites States, and other Nations, with massive cleanup and remediation tasks for radioactive and other legacy hazardous wastes. While some sites can be cleaned up to acceptable residential risk levels, others will continue to hold hazardous wastes, which must be contained and monitored to protect human health and the environment. While media (soil, sediment, groundwater) monitoring is the usual norm at many radiological waste sites, for some situations (both biological and societal), biomonitoring may provide the necessary information to assure greater peace of mind for local and regional residents, and to protect ecologically valuable buffer lands or waters. In most cases, indicators are selected using scientific expertise and a literature review, but not all selected indicators will seem relevant to stakeholders. In this paper, I provide a model for the inclusion of stakeholders in the development of bioindicators for assessing radionuclide levels of biota in the marine environment around Amchitka Island, in the Aleutian Chain of Alaska. Amchitka was the site of three underground nuclear tests from 1965 to 1971. The process was stakeholder-initiated, stakeholder-driven, and included stakeholders during each phase. Phases included conceptualization, initial selection of biota and radionuclides, refinement of biota and radionuclide target lists, collection of biota, selection of biota and radionuclides for analysis, and selection of biota, tissues, and radionuclides for bioindicators. The process produced site-specific information on biota availability and on radionuclide levels that led to selection of site-appropriate bioindicators. I suggest that the lengthy, iterative, stakeholder-driven process described in this paper results in selection of bioindicators that are accepted by biologists, public health personnel, public-policy makers, resource agencies, regulatory agencies, subsistence hunters/fishers, and a wide range of other stakeholders. The process is applicable to other sites with ecologically important buffer lands or waters, or where contamination issues are contentious.

  17. A model for selecting bioindicators to monitor radionuclide concentrations using Amchitka Island in the Aleutians as a case study.

    PubMed

    Burger, Joanna

    2007-11-01

    World War II and the Cold War have left the Unites States, and other Nations, with massive cleanup and remediation tasks for radioactive and other legacy hazardous wastes. While some sites can be cleaned up to acceptable residential risk levels, others will continue to hold hazardous wastes, which must be contained and monitored to protect human health and the environment. While media (soil, sediment, groundwater) monitoring is the usual norm at many radiological waste sites, for some situations (both biological and societal), biomonitoring may provide the necessary information to assure greater peace of mind for local and regional residents, and to protect ecologically valuable buffer lands or waters. In most cases, indicators are selected using scientific expertise and a literature review, but not all selected indicators will seem relevant to stakeholders. In this paper, I provide a model for the inclusion of stakeholders in the development of bioindicators for assessing radionuclide levels of biota in the marine environment around Amchitka Island, in the Aleutian Chain of Alaska. Amchitka was the site of three underground nuclear tests from 1965 to 1971. The process was stakeholder-initiated, stakeholder-driven, and included stakeholders during each phase. Phases included conceptualization, initial selection of biota and radionuclides, refinement of biota and radionuclide target lists, collection of biota, selection of biota and radionuclides for analysis, and selection of biota, tissues, and radionuclides for bioindicators. The process produced site-specific information on biota availability and on radionuclide levels that led to selection of site-appropriate bioindicators. I suggest that the lengthy, iterative, stakeholder-driven process described in this paper results in selection of bioindicators that are accepted by biologists, public health personnel, public-policy makers, resource agencies, regulatory agencies, subsistence hunters/fishers, and a wide range of other stakeholders. The process is applicable to other sites with ecologically important buffer lands or waters, or where contamination issues are contentious. PMID:17698056

  18. The geomorphology of the flanks of the Lord Howe Island volcano, Tasman Sea, Australia

    NASA Astrophysics Data System (ADS)

    Kennedy, D. M.; Brooke, B. P.; Woodroffe, C. D.; Jones, B. G.; Waikari, C.; Nichol, S.

    2011-04-01

    The flanks of mid-ocean volcanoes are inherently unstable features especially in the constructional phase of development when the volcano is active. Lateral and vertical stresses are placed on the volcanic edifice as it builds, with the flanks continuing to be unstable up to at least 1 Ma after volcanism has ceased. The flanks of the Lord Howe Island volcano record this period of greatest instability and a subsequent period in which marine and subaerial erosion have dominated its geomorphic evolution. Lord Howe Island lies in the Tasman Sea of the Southern Pacific region and is the subaerial remnant of a Miocene mid-ocean volcano. The island has only recently entered reef building seas and therefore has been subject to marine erosive processes over the past 5-6 Ma. The island is unique as it sits on the stable drowned continental crust of the Lord Howe Rise rather than oceanic crust like many other mid-plate basaltic islands. Multibeam sonar bathymetry data were collected to a depth of 3500 m where the island flanks grade into the surrounding planar sea floor. Several slump features are evident, the largest being over 130 km 2 in area. These features are inferred to be old (late Tertiary) based on an extensive cover of marine sediment as indicated by low multibeam backscatter intensity and subdued topography. Most likely the slumps formed during the immediate post-eruptive stage of volcano evolution, before the bulk of the subaerial portion of the volcano was removed by marine erosion. Flank processes are now dominated by the deposition of carbonate sediment composed of mollusc and foraminiferal remains. Based on radiocarbon and stable isotope analyses of a sediment core (760 m depth) collected on a trough in the centre of the volcanic edifice, Quaternary sediment was likely deposited predominantly during glacial periods. The erosional morphology, sediment cover and tectonic stability of the region suggest that the flanks of the volcano are at present relatively stable.

  19. Specification of Tectonic Tsunami Sources Along the Eastern Aleutian Island Arc and Alaska Peninsula for Inundation Mapping and Hazard Assessment

    NASA Astrophysics Data System (ADS)

    Suleimani, E.; Nicolsky, D.; Freymueller, J. T.; Koehler, R.

    2013-12-01

    The Alaska Earthquake Information Center conducts tsunami inundation mapping for coastal communities in Alaska along several segments of the Aleutian Megathrust, each having a unique seismic history and tsunami generation potential. Accurate identification and characterization of potential tsunami sources is a critical component of our project. As demonstrated by the 2011 Tohoku-oki tsunami, correct estimation of the maximum size event for a given segment of the subduction zone is particularly important. In that event, unexpectedly large slip occurred approximately updip of the epicenter of the main shock, based on seafloor GPS and seafloor pressure gage observations, generating a much larger tsunami than anticipated. This emphasizes the importance of the detailed knowledge of the region-specific subduction processes, and using the most up-to-date geophysical data and research models that define the magnitude range of possible future tsunami events. Our study area extends from the eastern half of the 1957 rupture zone to Kodiak Island, covering the 1946 and 1938 rupture areas, the Shumagin gap, and the western part of the 1964 rupture area. We propose a strategy for generating worst-case credible tsunami scenarios for locations that have a short or nonexistent paleoseismic/paleotsunami record, and in some cases lack modern seismic and GPS data. The potential tsunami scenarios are built based on a discretized plate interface model fit to the Slab 1.0 model geometry. We employ estimates of slip deficit along the Aleutian Megathrust from GPS campaign surveys, the Slab 1.0 interface surface, empirical magnitude-slip relationships, and a numerical code that distributes slip among the subfault elements, calculates coseismic deformations and solves the shallow water equations of tsunami propagation and runup. We define hypothetical asperities along the megathrust and in down-dip direction, and perform a set of sensitivity model runs to identify coseismic deformation patterns resulting in highest runup at a given community. Because of the extra fine discretization of the interface, we can prescribe variable slip patterns, using simple parameters to describe slip variations in the along-strike and down-dip directions. Since it was demonstrated by studies of the 1964 tsunami that changes in slip distribution result in significant variations in the local tsunami wave field, we expect that the near-field tsunami runup in target communities will be highly sensitive to variability of slip along the rupture area. We perform simulations for each source scenario using AEIC's numerical model of tsunami propagation and runup, which is validated through a set of analytical benchmarks and tested against laboratory and field data. Results of numerical modeling combined with historical observations are compiled on inundation maps and used for site-specific tsunami hazard assessment by local emergency planners.

  20. Monitoring the evolution of Deception Island volcano from magnetic anomaly data (South Shetland Islands, Antarctica)

    NASA Astrophysics Data System (ADS)

    Catalán, Manuel; Martos, Yasmina M.; Galindo-Zaldívar, Jesús; Funaki, Minoru

    2014-12-01

    Deception Island is a young and active volcano located in the south-western part of Bransfield back-arc basin. During the last twenty years the Royal Observatory of the Spanish Navy has carried out geophysical surveys in the area. In addition, an unmanned aerial vehicle flight was conducted in 2011 at 800 m height on the northern half of Deception Island. Analysing and comparing magnetic grids obtained in different periods and tie point readings allow us to detect temporal changes and isolate signals of volcanic origin. Magnetic survey cruises performed in Deception Island's inner bay (1988, 1999 and 2008), and the study of its outer area's magnetic anomaly changes, point to a period of high variations concentrated between December 1989 and December 1999 that may be related to the two main recent periods of seismic activity (1992 and January 1999). From December 1999 to December 2008, there were no significant changes in seismic activity; nevertheless, our data show some magnetic alterations, which might signal the slow progress of a volcanic environment towards equilibrium. Interpreting these magnetic changes called for the construction of several forward models. Additionally, we put forth this kind of study as a suitable, economical and easy method for monitoring an active volcanic system whenever it is possible to measure the magnetic field with accurate positioning, and if the external field components are removed correctly.

  1. Observations of Seafloor Outcrops in the Oblique Subduction Setting of Adak Canyon: Implications for Understanding the Early History of the Aleutian Island Arc

    NASA Astrophysics Data System (ADS)

    Yogodzinski, G.; Scholl, D.; Jicha, B.; Wyatt, C.; Singer, B.; Kelemen, P.

    2004-12-01

    Submarine canyons in the western Aleutians (west of 177°W) are formed by oblique subduction, which has broken crustal blocks away from the arc massif and rotated them in clockwise sense, resulting in the formation of triangular-shaped summit basins and deep, structurally controlled submarine canyons (Geist et al., Tectonics v7, p327, 1988). A series of dives with the ROV Jason II on July 28-30, 2004 on Adak Canyon has provided the first-ever view of seafloor outcrops in an Aleutian canyon formed by this process. Two dives on the canyon's steep eastern wall revealed extensive exposures of blocky outcrops of volcanic rock at depths of 2900-1500 m. Samples of these units collected by the Jason II are a mixture of dark, pyroxene and plagioclase-phyric lavas and volcaniclastics. Degree of weathering/alteration is highly variable but some samples appear fresh. We anticipate that these rocks are offshore-equivalents of the Finger Bay Volcanics, which represent the earliest phase of Aleutian volcanism exposed on nearby Adak Island (e.g., Coats, 1956, USGS Bull. 1028-C). Exposures of granitic rock in Adak Canyon form low ledges of exfoliating outcrop interspersed with spheroidally weathered, bouldery sub-crop, in the depth range of 1800-1600 meters. Obtaining in-situ samples from these massive and subrounded exposures was not possible with the Jason II, but recovery of large, sub-angular slabs that litter the surface included samples of fresh diorite, fine-grained felsic intrusives and hydrothermally altered volcanic country rock. The stratigraphically highest exposures observed in Adak Canyon are gently dipping, poorly lithified `Middle Series' sedimentary rocks of probable Miocene-Oligocene age. All outcrop surfaces in Adak Canyon are covered with a uniformly dark brown, opaque coating of Mn oxide less than 1mm thick. Well-rounded cobbles and boulders interpreted to be glacial drift are largely free of Mn oxide coatings. Thick pavements of Mn-oxide were not observed. These observations indicate that combined seismic and dredging-geochemical studies will be a successful approach to unraveling the complete magmatic and tectonic history of the Aleutian arc crust, which due to the absence of significant arc-parallel rifting and backarc spreading remains largely intact and available for study. Dating and geochemical analysis of samples recovered on the July '04 Jason II expedition will provide a much-improved view of early Aleutian history.

  2. Hydroacoustic Records of the First Historical Eruption of Anatahan Volcano, Mariana Islands

    Microsoft Academic Search

    R. Dziak; H. Matsumoto; C. Fox; S. Byun; M. Fowler; J. Haxel; R. Embley

    2003-01-01

    For the past decade, NOAA\\/Pacific Marine Environmental Laboratory has monitored volcano-seismic activity from western Pacific island-arc volcanoes using an array of U.S. Navy hydrophones (called SOSUS) deployed at fixed locations throughout the North Pacific Ocean. SOSUS hydrophones are mounted within the SOFAR channel and record the hydroacoustic tertiary phase or T-wave of oceanic earthquakes from throughout the Pacific basin. Since

  3. 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

    2014-01-01

    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

  4. Testing the nutritional-limitation, predator-avoidance, and storm-avoidance hypotheses for restricted sea otter habitat use in the Aleutian Islands, Alaska

    USGS Publications Warehouse

    Stewart, Nathan L.; Konar, Brenda; Tinker, M. Tim

    2015-01-01

    Sea otters (Enhydra lutris) inhabiting the Aleutian Islands have stabilized at low abundance levels following a decline and currently exhibit restricted habitat-utilization patterns. Possible explanations for restricted habitat use by sea otters can be classified into two fundamentally different processes, bottom-up and top-down forcing. Bottom-up hypotheses argue that changes in the availability or nutritional quality of prey resources have led to the selective use of habitats that support the highest quality prey. In contrast, top-down hypotheses argue that increases in predation pressure from killer whales have led to the selective use of habitats that provide the most effective refuge from killer whale predation. A third hypothesis suggests that current restricted habitat use is based on a need for protection from storms. We tested all three hypotheses for restricted habitat use by comparing currently used and historically used sea otter foraging locations for: (1) prey availability and quality, (2) structural habitat complexity, and (3) exposure to prevailing storms. Our findings suggest that current use is based on physical habitat complexity and not on prey availability, prey quality, or protection from storms, providing further evidence for killer whale predation as a cause for restricted sea otter habitat use in the Aleutian Islands.

  5. Testing the nutritional-limitation, predator-avoidance, and storm-avoidance hypotheses for restricted sea otter habitat use in the Aleutian Islands, Alaska.

    PubMed

    Stewart, Nathan L; Konar, Brenda; Tinker, M Tim

    2015-03-01

    Sea otters (Enhydra lutris) inhabiting the Aleutian Islands have stabilized at low abundance levels following a decline and currently exhibit restricted habitat-utilization patterns. Possible explanations for restricted habitat use by sea otters can be classified into two fundamentally different processes, bottom-up and top-down forcing. Bottom-up hypotheses argue that changes in the availability or nutritional quality of prey resources have led to the selective use of habitats that support the highest quality prey. In contrast, top-down hypotheses argue that increases in predation pressure from killer whales have led to the selective use of habitats that provide the most effective refuge from killer whale predation. A third hypothesis suggests that current restricted habitat use is based on a need for protection from storms. We tested all three hypotheses for restricted habitat use by comparing currently used and historically used sea otter foraging locations for: (1) prey availability and quality, (2) structural habitat complexity, and (3) exposure to prevailing storms. Our findings suggest that current use is based on physical habitat complexity and not on prey availability, prey quality, or protection from storms, providing further evidence for killer whale predation as a cause for restricted sea otter habitat use in the Aleutian Islands. PMID:25416538

  6. The Canary Islands: An example of structural control on the growth of large oceanic-island volcanoes

    Microsoft Academic Search

    J. c. Carracedo

    1994-01-01

    Abstract Dike complexes, which are increasingly accepted as a common feature in the growth of most oceanic volcanoes, are well represented in the Canary Islands, where their deep structure can be readily observed through hundreds of infiltration galleries excavated for water mining. These intrusive complexes,have their surficial representation as narrow, clearly aligned clusters of emission centers that, cumulatively, form steep

  7. Volcanoes!!

    NSDL National Science Digital Library

    Kailey Fucaloro

    2009-09-15

    5th grade students will be able to explain what makes a volcano erupt. 5th grade students will be able to list the effects that volcanoes have on the environment and people. Read through the page to gather more knowledge about volcanoes. After reading this, you should be able to explain what makes a volcano erupt Volcano Facts View a model of a volcano erupting Visual Model of a volcano erupting Use the web tool to make your own volcano erupt. Adjust the gas level and size to make ...

  8. Inferring crustal structure in the Aleutian island arc from a sparse wide-angle seismic data set

    Microsoft Academic Search

    Harm J. A. Van Avendonk; Donna J. Shillington; W. Steven Holbrook; Matthew J. Hornbach

    2004-01-01

    Compressional seismic travel times from a relatively sparse wide-angle data set hold key information on the structure of a 800 km long section of the central Aleutian arc. Since the source and receiver locations form a swath along the arc crest that is ?50 km wide, we trace rays in 3-D for a collection of 8336 seismic refraction and reflection

  9. 76 FR 80782 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Proposed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ...final 2010 Stock Assessment and Fishery Evaluation...age-structured model for the Aleutian...Pacific cod stock assessment that will be reviewed...groups about the economic value of Kamchatka...as revised stock assessments and catch data...and changes to the models used in the...

  10. From birth to death of arc magmatism: The igneous evolution of Komandorsky Islands recorded tectonic changes during 50 Ma of westernmost Aleutian history

    NASA Astrophysics Data System (ADS)

    Höfig, T. W.; Portnyagin, M.; Hoernle, K.; Hauff, F. F.; van den Bogaard, P.; Garbe-Schoenberg, C.

    2013-12-01

    The Komandorsky Islands form the westernmost end of the Aleutian Island Arc. Four igneous complexes, spanning almost 50 Ma of magmatism, have previously been identified (Ivaschenko et al., 1984: Far East Scientific Centre, Vladivostok, 192 pp.). The petrogenesis of this protracted magmatic record and accurate absolute ages of events, however, remain poorly constrained. Our study investigates the relationship between magma composition and tectonic setting. The Komandorsky igneous basement formed in subduction zone setting. It hosts some of the oldest igneous rocks of the entire Aleutian Arc with the onset of magmatism occurring at 47 Ma. This early stage was characterized by classic fluid-dominated arc volcanism, which produced two coeval but likely genetically unrelated magmatic series of tholeiitic mafic and tholeiitic to calc-alkaline felsic rocks. To date, no boninites have been found and therefore arc initiation is different at the Aleutians than at Izu-Bonin-Marianas or the oldest rocks in the Aleutians have yet to be discovered. The prolonged production of the contrasting basalt-rhyolite association on Komandorsky Islands had lasted ~25 Ma and ceased around the Oligocene-Miocene boundary. Concurrently to this long-lasting activity, a gradual transition to a different mode of arc magmatism took place reflected by newly discovered Sr-enriched, HREE-depleted calc-alkaline basaltic andesitic lavas of mid-upper Eocene age spanning a time of at least ~7 Ma. This so-called Transition Series displays a moderate garnet signature marking the increased contribution of a slab-melt component to the magma sources of the Komandorsky Islands. Slab-melt contribution increased with decreasing age leading to strongly adakitic magmatism as early as ~33 Ma (Lower Oligocene), reflected by eruption of high-Sr (up to 2,500 ppm), highly HREE-depleted Adak-type magnesian basaltic andesites and andesites. These remarkable magmas became predominant during the Lower Miocene. They were followed at ~17 Ma by extremely HREE-depleted calc-alkaline intrusives. Over time there is a clear decrease in Pb isotopic ratios from radiogenic sediment-affected Central Aleutian to unradiogenic Pacific MORB-type compositions similar to Miocene Komandorsky Basin basalt. The geochemical evolution reflects a dramatic change in convergence direction from roughly orthogonal to highly oblique (Duncan and Keller, 2004: G-cubed, v. 5, Q08L03). Increasing oblique subduction led to intense stripping of sediment and enhanced heating of the flat-plunging Pacific lithosphere. This facilitated partial slab melting. However, a significantly increasing amount of slab melt in mid-late Miocene times required an additional heat source, which was probably provided by a slab tear or even slab break-off (Levin et al., 2005: Geology, v. 33, p. 253-256).

  11. Volcanoes

    NSDL National Science Digital Library

    Mrs. Walls

    2011-01-30

    Create a poster about volcanoes Directions: Make a poster about volcanoes. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about volcanoes. (5 points each) (15 points) Write at least a three sentence summary of your poster and volcanoes. (5 points) Use at ...

  12. Mercury, arsenic, cadmium, chromium lead, and selenium in feathers of pigeon guillemots (Cepphus columba) from Prince William Sound and the Aleutian Islands of Alaska.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Sullivan, Kelsey; Irons, David

    2007-11-15

    Arsenic, cadmium, chromium, lead, manganese, mercury and selenium were analyzed in the feathers of pigeon guillemots (Cepphus columba) from breeding colonies in Prince William Sound and in the Aleutian Islands (Amchitka, Kiska) to test the null hypothesis that there were no differences in metal levels as a function of location, gender, or whether the birds were from oiled or unoiled areas in Prince William Sound. Birds from locations with oil from the Exxon Valdez Oil Spill in the environment had higher levels of cadmium and lead than those from unoiled places in Prince William Sound, but otherwise there were no differences in metal levels in feathers. The feathers of pigeon guillemots from Prince William Sound had significantly higher levels of cadmium and manganese, but significantly lower levels of mercury than those from Amchitka or Kiska in the Aleutians. Amchitka had the lowest levels of chromium, and Kiska had the highest levels of selenium. There were few gender-related differences, although females had higher levels of mercury and selenium in their feathers than did males. The levels of most metals are below the known effects levels, except for mercury and selenium, which are high enough to potentially pose a risk to pigeon guillemots and to their predators. PMID:17765292

  13. Cumbre Vieja Volcano-Potential collapse and tsunami at La Palma, Canary Islands

    Microsoft Academic Search

    Steven N. Ward; Simon Day

    2001-01-01

    Geological evidence suggests that during a future eruption, Cumbre Vieja Volcano on the Island of La Palma may experience a catastrophic failure of its west flank, dropping 150 to 500 km3 of rock into the sea. Using a geologically reasonable estimate of landslide motion, we model tsunami waves produced by such a collapse. Waves generated by the run-out of a

  14. Hydroacoustic Records of the First Historical Eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Dziak, R.; Park, M.; Matsumoto, H.; Fox, C.; Byun, S.; Fowler, M.; Haxel, J.; Embley, R.

    2003-12-01

    For the past decade, NOAA/Pacific Marine Environmental Laboratory has monitored volcano-seismic activity from western Pacific island-arc volcanoes using an array of U.S. Navy hydrophones (called SOSUS) deployed at fixed locations throughout the North Pacific Ocean. SOSUS hydrophones are mounted within the SOFAR channel and record the hydroacoustic tertiary phase or T-wave of oceanic earthquakes from throughout the Pacific basin. Since acoustic T-waves obey cylindrical energy attenuation as opposed to the spherical attenuation of solid-earth seismic phases, sound channel hydrophones can detect often smaller and therefore more numerous earthquakes than land-based seismic networks. This property allowed for the detection of harmonic tremor from a submarine volcano in the Volcano Islands on hydrophones >14,000 km away in the eastern Pacific. The first historical eruption of Anatahan Volcano appears to have started (from satellite imagery) at 1730Z on 10 May, with an ash plume visible by 2232Z (BGVN, 5 May 2003). Records from a broadband seismometer deployed on nearby ( ˜6.5 km) Sarigan Island indicate earthquake activity increased at about 1300Z on 10 May (D. Weins, pers com). SOSUS hydrophones in the western Pacific ( ˜4000 km distant) also recorded increased earthquake activity at 1300Z on 10 May as well as continuous, low-frequency (<10 Hz) energy (possible volcanic tremor) that began about a day before the seismicity. The earthquakes and tremor were detected on only two SOSUS hydrophones and therefore it was not possible to estimate their source location. The arrival azimuth of the signals were, however, consistent with a source in the Mariana Islands. To complement the SOSUS hydrophone array coverage in the western Pacific Ocean, an array of five autonomous hydrophones were deployed in February 2003 (sponsored by NOAA's Ocean Exploration Program) within the SOFAR channel along the active island- and back-arc of the Mariana Islands. All five hydrophones (1-110 Hz bandpass) were deployed between 13° N and 22° N, with one hydrophone located within 50 km of Anatahan Island. These five hydrophone will be recovered in September 2003, and it is anticipated their data will provide insights into Anatahan, as well as Mariana Island wide, volcano-seismic activity.

  15. The petrogenesis of sodic island arc magmas at Savo volcano, Solomon Islands

    NASA Astrophysics Data System (ADS)

    Smith, D. J.; Petterson, M. G.; Saunders, A. D.; Millar, I. L.; Jenkin, G. R. T.; Toba, T.; Naden, J.; Cook, J. M.

    2009-12-01

    Savo, Solomon Islands, is a historically active volcano dominated by sodic, alkaline lavas, and pyroclastic rocks with up to 7.5 wt% Na2O, and high Sr, arc-like trace element chemistry. The suite is dominated by mugearites (plagioclase-clinopyroxene-magnetite ± amphibole ± olivine) and trachytes (plagioclase-amphibole-magnetite ± biotite). The presence of hydrous minerals (amphibole, biotite) indicates relatively wet magmas. In such melts, plagioclase is relatively unstable relative to iron oxides and ferromagnesian silicates; it is the latter minerals (particularly hornblende) that dominate cumulate nodules at Savo and drive the chemical differentiation of the suite, with a limited role for plagioclase. This is potentially occurring in a crustal “hot zone”, with major chemical differentiation occurring at depth. Batches of magma ascend periodically, where they are subject to decompression, water saturation and further cooling, resulting in closed-system crystallisation of plagioclase, and ultimately the production of sodic, crystal and feldspar-rich, high-Sr rocks. The sodic and hydrous nature of the parental magmas is interpreted to be the result of partial melting of metasomatised mantle, but radiogenic isotope data (Pb, Sr, Nd) cannot uniquely identify the source of the metasomatic agent.

  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. 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…

  19. Sheared sheet intrusions as mechanism for lateral flank displacement on basaltic volcanoes: Applications to Réunion Island volcanoes

    NASA Astrophysics Data System (ADS)

    Cayol, V.; Catry, T.; Michon, L.; Chaput, M.; Famin, V.; Bodart, O.; Froger, J.-L.; Romagnoli, C.

    2014-10-01

    Field work carried out on the Piton des Neiges volcano (Réunion Island) suggests that the injection of magma along detachments could trigger flank failure by conjugate opening and shear displacement. We use 3-D numerical models to compare the ability of purely opened sheet intrusions, sheared sheet intrusions, and normal faults to induce flank displacement on basaltic volcanoes. We assume that shear stress change on fractures results from stress anisotropy of the host rock under gravity. Exploring a large range of stress anisotropies, fracture dips, and fracture depth over length ratios, we determine that the amount of shear displacement is independent of the proximity to the ground surface. Sheared sheet intrusions are the most efficient slip medium on volcanoes. Consequently, the largest flank displacement is induced by the longest, deepest sheared intrusion dipping closest to 45° in a host rock with the highest stress anisotropy. Using our model in a forward way, we provide shear and normal displacements for buried fractures. Applying the model to a pile of sills at the Piton des Neiges volcano, we determine that the mean shear displacement caused by each intrusion was 3.7 m, leading to a total of a 180-260 m of lateral displacement for the 50 m high pile of sills. Using our model in an inverse way, we formulate a decision tree to determine some fracture characteristics and the host rock stress anisotropy from ratios of maximum surface displacements. This procedure provides a priori models, which can be used to bound the parameter space before it is explored through a formal inversion. Applying the decision tree to the 1.4 m coeruptive flank displacement recorded at Piton de la Fournaise in 2007, we find that it probably originated from a shallow eastward dipping subhorizontal normal fault.

  20. 3-D velocity model beneath Taal Volcano, Luzon Island Philippines

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    We derive a three dimensional velocity model of seismic waves beneath Taal Volcano, Philippines, from about 2300 local earthquakes recorded by the Taal Volcano seismic network during the time period from March 2008 to March 2010. In the early data processing stage, with the cross-correlation functions of continuous record of station pairs, unexpected linear drifting of clock time was clearly identified. The drifting rates of each problematic station were determined and the errors were corrected before further processing. With the corrected data, we first determined initial locations by using the program HYPO71 and the reference 1-D global model ak135. 749 well-located events with 3381 P-wave and 2896 S-wave arrivals were used to derive the 'minimum 1-D velocity model' with the program VELEST developed by Kissling to further improve the 1-D velocity model and event locations. With the robust 1-D velocity model and improved event locations, we inverted a high-resolution 3-D velocity model by using the program LOTOS-10 developed by Koulakov. We present the derived 3-D model and discuss its tectonic implications.

  1. Evaluation of landslide susceptibility of Sete Cidades Volcano (S. Miguel Island, Azores)

    NASA Astrophysics Data System (ADS)

    Gomes, A.; Gaspar, J. L.; Goulart, C.; Queiroz, G.

    2005-03-01

    Sete Cidades is an active central volcano with a summit caldera located in the westernmost part of S. Miguel Island (Azores). Since the settlement of the Island, in the 15th century, many landslide events occurred in this volcano, causing extensive damages in buildings and infrastructures. The study of historical records and the observation of new occurrences showed that landslides in the region have been triggered by heavy rainfall periods, earthquakes and erosion. In order to assess landslide susceptibility at Sete Cidades Volcano, landslide scars and associated deposits were mapped through aerial photographs and field surveys. The obtained data were inserted in a GIS to produce a landslide distribution map. It was concluded that the high density landslide areas are related with (1) major scarp faults, (2) the margin of fluvial channels, (3) the sea cliffs and (4) volcanic landforms, namely the caldera wall. About 73% of the mapped events took place in areas where pyroclastic deposits are the dominant lithology and more than 77% occurred where slopes are equal or higher than 20°. These two parameters were integrated and used to generate a preliminary susceptibility map. The incorporation of vulnerability data into the GIS allowed concluding that 30% of dwellings and most of the roads on Sete Cidades Volcano are located in areas where landslide susceptibility is high to very high. Such conclusion should be taken into account for emergency and land use planning.

  2. Estimate of sulfate emitted from Sakurajima volcano to the Japanese Islands

    SciTech Connect

    Mizuno, Tateki; Maeda, Takahisa [National Institute for Environment and Resources, Ibaraki (Japan); Tanaka, Chie; Takeuchi, Kiyohide

    1996-12-31

    Concentration of sulfate increased in a summer night over the wide area of the Kanto plain. Since the effect of long range transport of particulate sulfurs was suggested, Lagrangian dispersion-advection analysis of particles was carried out using global scale weather analytical data. Results show that the concentration observed at the Kanto plain coupled be increased by the effect of the volcanic gas which had been emitted from an active volcano {open_quotes}Sakurajima{close_quotes}, located in the distance of about 1,00 km at south-west of the Kanto area, before 3 days. This phenomenon suggests that sulfate emitted from the active volcano Sakurajima might affect acid deposition of all over the Japanese Islands. This report shows estimated concentration of deposition of sulfate from Sakurajima to the Japan Islands using the same model applied to the Kanto area.

  3. Central Aleutian tundra: ecological manifestations of maritime tundra landscapes in the Central Aleution Islands (Amchitka, Adak) Alaska. Final report, 1 April 1971-15 November 1985

    SciTech Connect

    Amundsen, C.C.

    1985-01-01

    Measured and inferred ecological characteristics and holocoenotic factors which affect the dynamics and manifestations of central Aleutian maritime tundra and beach-dune vegetational expressions of Adak and Amchitka Islands are discussed. The known vascular flora is enumerated and predominant taxa are grouped into communities and topoedaphic units. Stability of community composition and structure is elaborated and the absence of ecological succession demonstrated. Perturbations occasioned by human activities which impinge on these remote islands are detailed. The testing and monitoring of subsequent passive and managed recovery of stable vegetation on disturbed areas is described. Selection, preparation and utilization of transplants of Elymus mollis Trin. is documented. Transplants of rhizomes of E. mollis are successful in the reestablishment of vegetative cover in disturbed habitats which are topoedaphically suitable for graminoid success. The responses of plant population stands to environmental processes and habitat insults are reported. The relatively limited but stable biota and the lethargic ecological response as defined by extant vegetational expressions provide field test potentials which mandate further basic and applied research.

  4. Volcanoes

    NSDL National Science Digital Library

    2005-12-17

    Students investigate the processes that build volcanoes, the factors that influence different eruption types, and the threats volcanoes pose to their surrounding communities. They use what they have learned to identify physical features and eruption types of several actual volcanic episodes.

  5. Volcanoes!

    NSDL National Science Digital Library

    This site presents a summary of current volcanic eruptions and images and videos of volcanoes on Earth. Discussions of the characteristics of volcanism on other worlds in our solar system are also presented and are accompanied by maps and imagery. Links to volcano observatories, parks, and monuments around the world are also included.

  6. Comprehensive study of the seismotectonics of the eastern Aleutian arc and associated volcanic systems. Annual progress report, March 1, 1980-February 28, 1981

    SciTech Connect

    Jacob, K.H.; Davies, J.N.; House, L.

    1981-01-01

    Refined hypocenter locations beneath the Shumagin Islands seismic network of the eastern Aleutian arc, Alaska, provide for the first time conclusive evidence for a double-sheeted dipping seismic (Benioff) zone in this arc. This refined seismicity structure was obtained in the arc section centered on the Shumagin seismic gap. A thorough review of three seismic gaps in the eastern Aleutian arc shows a high potential for great earthquakes within the next one to two decades in the Shumagin and Yakataga seismic gaps, and a less certain potential for a large or great earthquake in the possible Unalaska gap. A tilt reversal was geodetically observed to have occurred in 1978/79 in the forearc region of the Shumagin gap and could indicate the onset of a precursory strain relief episode prior to a great quake. A comparative study of the Pavlof volcano seismicity with that of other recently active volcanoes (i.e., Mt. St. Helens) indicates that island-arc (explosive-type) volcanoes respond to small ambient, periodic stress changes (i.e., tides). Stress drop measurements from earthquakes on the main thrust zone indicate high stress drops within the seismic gap regions of the Aleutian arc and low stress drops outside the gap region.

  7. A Stratigraphic, Granulometric, and Textural Comparison of recent pyroclastic density current deposits exposed at West Island and Burr Point, Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Rath, C. A.; Browne, B. L.

    2011-12-01

    Augustine Volcano (Alaska) is the most active volcano in the eastern Aleutian Islands, with 6 violent eruptions over the past 200 years and at least 12 catastrophic debris-avalanche deposits over the past ~2,000 years. The frequency and destructive nature of these eruptions combined with the proximity of Augustine Volcano to commercial ports and populated areas represents a significant hazard to the Cook Inlet region of Alaska. The focus of this study examines the relationship between debris-avalanche events and the subsequent emplacement of pyroclastic density currents by comparing the stratigraphic, granulometric, and petrographic characteristics of pyroclastic deposits emplaced following the 1883 A.D. Burr Point debris-avalanche and those emplaced following the ~370 14C yr B.P. West Island debris-avalanche. Data from this study combines grain size and componentry analysis of pyroclastic deposits with density, textural, and compositional analysis of juvenile clasts contained in the pyroclastic deposits. The 1883 A.D. Burr Point pyroclastic unit immediately overlies the 1883 debris avalanche deposit and underlies the 1912 Katmai ash. It ranges in thickness from 4 to 48 cm and consists of fine to medium sand-sized particles and coarser fragments of andesite. In places, this unit is normally graded and exhibits cross-bedding. Many of these samples are fines-enriched, with sorting coefficients ranging from -0.1 to 1.9 and median grain size ranging from 0.1 to 2.4 mm. The ~370 14C yr B.P. West Island pyroclastic unit is sandwiched between the underlying West Island debris-avalanche deposit and the overlying 1912 Katmai Ash deposit, and at times a fine-grained gray ash originating from the 1883 eruption. West Island pyroclastic deposit is sand to coarse-sand-sized and either normally graded or massive with sorting coefficients ranging from 0.9 to 2.8 and median grain sizes ranging from 0.4 to 2.6 mm. Some samples display a bimodal distribution of grain sizes, while most display a fines-depleted distribution. Juvenile andesite clasts exist as either subrounded to subangular fragments with abundant vesicles that range in color from white to brown or dense clasts characterized by their porphyritic and glassy texture. Samples from neither eruption correlate in sorting or grain size with distance from the vent. Stratigraphic and granulometric data suggest differences in the manner in which these two pyroclastic density currents traveled and groundmass textures are interpreted as recording differences in how the two magmas ascended and erupted, whereas juvenile Burr Point clasts resemble other lava flows erupted from Augustine Volcano, vesicular and glassy juvenile West Island clasts bear resemblance to clasts derived from so-called "blast-generated" pyroclastic density deposits at Mt. St. Helens in 1980 and Bezymianny in 1956.

  8. Growth and collapse of the Reunion Island volcanoes

    Microsoft Academic Search

    Jean-François Oehler; Jean-François Lénat; Philippe Labazuy

    2008-01-01

    This work presents the first exhaustive study of the entire surface of the Reunion Island volcanic system. The focus is on\\u000a the submarine part, for which a compilation of all multibeam data collected during the last 20 years has been made. Different\\u000a types of submarine features have been identified: a coastal shelf, debris avalanches and sedimentary deposits, erosion canyons,\\u000a volcanic constructions

  9. Evidence for Deep Tectonic Tremor in the Alaska-Aleutian Subduction Zone

    NASA Astrophysics Data System (ADS)

    Brown, J. R.; Prejean, S. G.; Beroza, G. C.; Gomberg, J. S.; Haeussler, P. J.

    2010-12-01

    We search for, characterize, and locate tremor not associated with volcanoes along the Alaska-Aleutian subduction zone using continuous seismic data recorded by the Alaska Volcano Observatory and Alaska Earthquake Information Center from 2005 to the present. Visual inspection of waveform spectra and time series reveal dozens of 10 to 20-minute bursts of tremor throughout the Alaska-Aleutian subduction zone (Peterson, 2009). Using autocorrelation methods, we show that these tremor signals are composed of hundreds of repeating low-frequency earthquakes (LFEs) as has been found in other circum-Pacific subduction zones. We infer deep sources based on phase arrival move-out times of less than 4 seconds across multiple monitoring networks (max. inter-station distances of 50 km), which are designed to monitor individual volcanoes. We find tremor activity is localized in 7 segments: Cook Inlet, Shelikof Strait, Alaska Peninsula, King Cove, Unalaska-Dutch Harbor, Andreanof Islands, and the Rat Islands. Locations along the Cook Inlet, Shelikof Straight and Alaska Peninsula are well constrained due to adequate station coverage. LFE hypocenters in these regions are located on the plate interface and form a sharp edge near the down-dip limit of the 1964 M 9.2 rupture area. Although the geometry, age, thermal structure, frictional and other relevant properties of the Alaska-Aleutian subduction are poorly known, it is likely these characteristics differ along its entire length, and also differ from other subduction zones where tremor has been found. LFE hypocenters in the remaining areas are also located down-dip of the most recent M 8+ megathrust earthquakes, between 60-75 km depth and almost directly under the volcanic arc. Although these locations are less well constrained, our preliminary results suggest LFE/tremor activity marks the down-dip rupture limit for megathrust earthquakes in this subduction zone. Also, we cannot rule out the possibility that our observations could be related deep magmatic processes.

  10. Spreading Flanks of Ocean-Island Volcanoes: Similarities and Differences at Mauna Loa and Kilauea, Hawaii

    NASA Astrophysics Data System (ADS)

    Lipman, P. W.; Eakins, B. W.; Yokose, H.

    2003-12-01

    Submarine-flank deposits of Hawaiian volcanoes are widely recognized to have formed largely by gravitationally driven volcano spreading and associated landsliding. Observations from JAMSTEC submersibles (Japan Marine Science and Technology Center) show that prominent benches at mid-depths on flanks of both Mauna Loa and Kilauea consist of volcaniclastic debris derived by landsliding from nearby shallow submarine and subaerial flanks of the same edifice. Both volcanoes have mid-slope benches that record the same general processes of slope failure on varying scales, followed by modest compression during continued volcano spreading, even though they record development during different stages of edifice growth. Massive slide breccias from the mature subaerial tholeiitic shield of Mauna Loa underlie the frontal scarp of its South Kona bench. Outboard of the South Kona bench are large slide blocks, containing mixed subaerial and submarine Mauna Loa rocks, that appear to constitute a distal facies of the same large landslide event(s). The dive results also suggest that volcaniclastic rocks at the north end of the Kona bench, interpreted by others as distal sediments from older volcanoes that were offscraped, uplifted, and accreted to the island by far-traveled thrusts, alternatively are a largely coherent stratigraphic assemblage deposited in a basin behind the South Kona bench. In contrast, the Hilina bench developed as Kilauea volcano has spread seaward, in part riding piggyback on the still active south flank of Mauna Loa. The Hilina bench is underlain by coarse volcaniclastic sediments derived largely from submarine-erupted pre-shield alkalic and transitional basalts of ancestral Kilauea. The south flank of Kilauea is thus far not associated with any massive slide deposits comparable to the distal blocks of the South Kona slide complex.

  11. A new model for the formation of linear rift zones on oceanic island volcanoes

    NASA Astrophysics Data System (ADS)

    Kluegel, A.; Walter, T. R.

    2003-04-01

    Oceanic island volcanoes commonly contain rift zones along which eruptive centers and parallel dike complexes are concentrated. Formation and orientation of rifts often remain enigmatic, however. Tectonic lineaments and regional zones of weakness facilitating magma ascent may be one reason of rift evolution, e.g. Sao Jorge (Azores) or Iceland. Alternatively, gravity tectonics of a volcano may cause formation of dike swarms oriented parallel to the line of contact between overlapping volcanic edifices (e.g. Kilauea / Mauna Loa, Hawaiian Islands). We have evidence that spreading of overlapping edifices can produce two types and orientations of dike complexes. A direction perpendicular to classic "Kilauea type" rifts is typified in the pronounced rift zones of La Palma (Canary Islands) and Madeira/Desertas islands. We suggest that these rift systems formed by edifice coalescence with a main spreading zone perpendicular to the initial line of contact between two volcanoes. Intrusions and eruptions focused along the resulting rift connecting the once separated volcanic cones, which successively grew together. Based on experimental studies we show that this mechanism works if the edifices overlap at lower (submarine) slopes and are situated both on weak substratum. By mounting analogue sand piles onto a viscous PDMS substratum, the setups represented the presumed pre-rift situations at La Palma and Madeira with small initial cones adjacent to the larger shields. Gravitative spreading of these cones produced fractures that mimic the orientation of both islands' present rift zones. The results are in agreement with the observation of an apparently old submarine cone at the southern end of the La Palma rift zone. Likewise, on Madeira, the terminal parts of the Desertas rift arm and of a recently discovered submarine rift zone off the island are both marked by a concentration of eruptive centers. Our results may also provide a clue why the rift zone of Loihi seamount (Hawaii) is oriented nearly perpendicular to the rifts of adjacent Kilauea rather than parallel to them. We conclude that the effect of spreading and buttressing on large volcanic edifices may diverge laterally, where rifting between two edifices is (i) perpendicular to their line of contact if edifice overlap is minor developed, but (ii) parallel to this line if one volcano is only an attached part of a larger edifice. Once formed, these rifts stabilize themselves by alternating constructive and destructive processes.

  12. Hydrogeochemical, Stable Isotopes and Hydrology of Fogo Volcano Perched Aquifers: São Miguel Island, Azores (Portugal)

    NASA Astrophysics Data System (ADS)

    Antunes, P. C.; Boutt, D. F.; Martini, A. M.; Ferstad, J.; Rodrigues, F. C.

    2012-12-01

    Fogo Volcano is located at central part of São Miguel Island and corresponds to a polygenetic volcano with a caldera made by an intercalated accumulation of volcaniclastic deposits and lava flows. São Miguel Island is one of the nine volcanic islands that form the Azores Archipelago. The volcano is 950 meters high, with a caldera diameter of 3.2 Km, which holds a lake inside. The last eruption occurred in 1563-1564, as one of a group of seven traquitic eruptions occurring within the last 5000 years. The volcanic activity is related to hydrothermal activity in a geothermal field located in the volcanoes North flank. The hydrology of Fogo Volcano is characterized by a series of perched-water bodies drained by a large number of springs grouped at different altitudes on the volcano flanks. It is possible to identify three types of water (1) Fresh water, cold temperature (12 - 17 C) with low dissolved solids contents (average conductivity of 179 ?S/cm), pH range between 6.60 and 7.82, dominated by the major ions Na, K, HCO3, and Cl, and correspond mainly to sodium bicarbonate type water. (2) Mineral water, cold temperature (12.5 - 19.4 C) with low dissolved solids contents (average conductivity of 261 ?S/cm), acid pH range between 4.62 and 6.79, and correspond mainly to sodium bicarbonate type water. (3) Thermal water, with temperature of 32 C, high dissolved solids content (4.62 mS/cm), with a pH around 4.50 and belongs to sodium sulfate type water. South Fogo volcano have only fresh water springs and at high elevation, springs drained from pumice fall deposits near 700 m of altitude. Water dissolved solids contents increased slightly with springs at lower altitude due to water-rock interaction. Springs sampled around 700 m high have a conductivity average of 85 ?S/cm, at 520 m an average of 129 ?S/cm, at 430 m an average of 182 ?S/cm, at 200 m an average of 192 ?S/cm and at 12 m high sea level and average of 472 ?S/cm. This trend is observed at North Fogo volcano flank for fresh water springs. Mineral and thermal waters show an influence of magmatic input, a natural water pollution source in areas with volcanic activity. Rainwater isotopic composition showed elevation effect variation with lighter ?18O and ?D values and recharge appear to be at highest altitudes with influence of sea salt from atmospheric contamination. Evaporation is clearly associated with mineral and thermal waters. Hydrogeochemistry differentiates the low altitude springs at South volcano flank where they are separated by ultramafic intrusions supporting the existence of dike impounded aquifers as Peterson (1972) proposed with the Hawaiian conceptual model for volcanic islands.

  13. 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.

  14. Preliminary Volcano-Hazard Assessment for the Tanaga Volcanic Cluster, Tanaga Island, Alaska

    USGS Publications Warehouse

    Coombs, Michelle L.; McGimsey, Robert G.; Browne, Brandon L.

    2007-01-01

    Summary of Volcano Hazards at Tanaga Volcanic Cluster The Tanaga volcanic cluster lies on the northwest part of Tanaga Island, about 100 kilometers west of Adak, Alaska, and 2,025 kilometers southwest of Anchorage, Alaska. The cluster consists of three volcanoes-from west to east, they are Sajaka, Tanaga, and Takawangha. All three volcanoes have erupted in the last 1,000 years, producing lava flows and tephra (ash) deposits. A much less frequent, but potentially more hazardous phenomenon, is volcanic edifice collapse into the sea, which likely happens only on a timescale of every few thousands of years, at most. Parts of the volcanic bedrock near Takawangha have been altered by hydrothermal activity and are prone to slope failure, but such events only present a local hazard. Given the volcanic cluster's remote location, the primary hazard from the Tanaga volcanoes is airborne ash that could affect aircraft. In this report, we summarize the major volcanic hazards associated with the Tanaga volcanic cluster.

  15. Dynamics of diffuse carbon dioxide emissions from Cumbre Vieja volcano, La Palma, Canary Islands

    NASA Astrophysics Data System (ADS)

    Padrón, Eleazar; Pérez, Nemesio M.; Rodríguez, Fátima; Melián, Gladys; Hernández, Pedro A.; Sumino, Hirochika; Padilla, Germán; Barrancos, José; Dionis, Samara; Notsu, Kenji; Calvo, David

    2015-04-01

    We report herein the results of 13 soil CO2 efflux surveys at Cumbre Vieja volcano, La Palma Island, the most active basaltic volcano in the Canary Islands. The CO2 efflux measurements were undertaken using the accumulation chamber method between 2001 and 2013 to constrain the total CO2 output from the studied area and to evaluate occasional CO2 efflux surveys as a volcanic surveillance tool for Cumbre Vieja. Soil CO2 efflux values ranged from non-detectable up to 2442 g m-2 days-1, with the highest values observed in the south, where the last volcanic eruption took place (Teneguía, 1971). Isotopic analyses of soil gas carbon dioxide suggest an organic origin as the main contribution to the CO2 efflux, with a very small magmatic gas component observed at the southern part of the volcano. Total biogenic and magmatic combined CO2 emission rates showed a high temporal variability, ranging between 320 and 1544 t days-1 and averaging 1147 t days-1 over the 220-km2 region. Two significant increases in the CO2 emission observed in 2011 and 2013 were likely caused by an enhanced magmatic endogenous contribution revealed by significant changes in the 3He/4He ratio in a CO2-rich cold spring. The relatively stable emission rate presented in this work defines the background CO2 emission range for Cumbre Vieja during a volcanic quiescence period.

  16. Temporal source evolution and crustal contamination at Lopevi Volcano, Vanuatu Island Arc

    NASA Astrophysics Data System (ADS)

    Beaumais, Aurélien; Chazot, Gilles; Dosso, Laure; Bertrand, Hervé

    2013-08-01

    Here we present a new geochemical study of Lopevi volcano, one the most active volcanoes in the Vanuatu island arc. We focus on the temporally well-defined sequence of lava flows emitted since 1960, and for the first time, on pre-1960 volcanic products, including high-MgO basalts and felsic andesites, the most evolved lavas sampled so far on this island. This work reports the first Pb and Hf isotopic study of lavas from Lopevi island. These lavas display correlations between differentiation indexes such as SiO2 content and isotopic ratios. The felsic andesites extend the known correlations with both the least (Sr-Pb) and the most (Nd-Hf) radiogenic isotopic compositions on the island. Our results confirm that the rising magma interacted with the sub-arc crust. Assimilation-Fractional Crystallization (AFC) quantitative modeling of trace element ratios and isotopic compositions requires 1% and 10% of assimilated partial melts of a mafic oceanic crust to account for the pre- and post-1960 lavas, respectively. The post-1960 lavas differ from the former lavas emitted ~ 20 years earlier by enrichments in fluid mobile elements (K, Ba, Rb…), Th, and Light Rare Earth Elements (LREE). We ascribe these features to slight variations in the metasomatic agent added to the sub-arc mantle and ultimately derived from the subducted lithosphere. However, the contrasting time scales involved in subducted lithosphere dehydration and magma genesis, relative to the time elapsed between eruptions of the two lava series, suggest that two different portions of mantle which have undergone slightly different metasomatism, gave birth to the Lopevi lavas. These distinct magmas are still present beneath the volcano.

  17. 75 FR 3873 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-25

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Eastern Aleutian District and...total allowable catch (TAC) of Atka mackerel in these areas for vessels...

  18. 75 FR 53606 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-01

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Eastern Aleutian District and...total allowable catch (TAC) of Atka mackerel in these areas by vessels...

  19. Man against volcano: The eruption on Heimaey, Vestmann Islands, Iceland

    USGS Publications Warehouse

    Williams, R.S., Jr.; Moore, J.G.

    1976-01-01

    The U.S. Geological Survey carries out scientific studies in the geological, hydrological, and cartographic sciences generally within the 50 states, but also in cooperation with scientific organizations in many foreign countries for the investigation of unusual earth science phenomena throughout the world. The following material discusses the impact of the 1973 volcanic eruption of Eldfell on the fishing port of Vestmannaeyjar on the island of Heimaey, Iceland. Before the eruption was over, approximately one-third of the town of Vestmannaeyjar had been obliterated but, more importantly, the potential damage had been reduced markedly by the spraying of seawater onto the advancing lava flows, causing them to be slowed, stopped, or diverted from the undamaged portion of the town. The Survey's interest and involvement in the Heimaey eruption in Iceland was occasioned by the possibility that the procedures used to control the course of the flowing lava and to reduce the damage in a modern town may some day be needed in Hawaii and possibly even in the continental United States. This publication is based on the observations of two USGS geologists, Richard S. Williams, Jr. and James G. Moore, as well as on information from the Icelandic Ministry for Foreign Affairs, Icelandic scientists' reports through the Center for Short-Lived Phenomena, and other published scientific reports. A number of Icelandic scientists studied the scientific aspects of the eruption and the engineering aspects of the control of lava flows, in particular, Professors Thorbjb'rn Sigurgeirsson and Sigurdur Thorarinsson of the University of Iceland Science Institute. Also, Icelandic governmental officials provided logistical and other support, in particular, Mr. Steingnmur Hermannsson, Director, Icelandic National Research Council and Professor Magnus Magnusson, Director, University of Iceland Science Institute.

  20. Eruption of soufriere volcano on st. Vincent island, 1971-1972.

    PubMed

    Aspinall, W P; Sigurdsson, H; Shepherd, J B

    1973-07-13

    The Soufrière volcano in St. Vincent erupted from October 1971 to March 1972, as 80 x 10(6) m(3) of basaltic andesite lava was quietly extruded inside the mile-wide crater. The eruption was largely subaqueous, taking place in the 180-m-deep crater lake, and resulted in the emergence of a steep-sided island. The mild character of the eruption and the absence of seismic activity stand in direct contrast to the highly explosive character of the eruption of 1902 to 1903. PMID:17746610

  1. Recent structural evolution of the Cumbre Vieja volcano, La Palma, Canary Islands: volcanic rift zone reconfiguration as a precursor to volcano flank instability?

    NASA Astrophysics Data System (ADS)

    Day, S. J.; Carracedo, J. C.; Guillou, H.; Gravestock, P.

    1999-12-01

    The Cumbre Vieja volcano is the youngest component of the island of La Palma. It is a very steep-sided oceanic island volcano, of a type which may undergo large-scale lateral collapse with little precursory deformation. Reconfiguration of the volcanic rift zones and underlying dyke swarms of the volcano is used to determine the present degree of instability of the volcano. For most of its history, from before 125 ka ago to around 20 ka, the Cumbre Vieja volcano was characterised by a triple ("Mercedes Star") volcanic rift zone geometry. The three rift zones were unequally developed, with a highly productive south rift zone and weaker NE and NW rift zones: the disparity in activity was probably due to topographic-gravitational stresses associated with the west facing Cumbre Nueva collapse structure underneath the western flank of the Cumbre Vieja. From 20 ka to about 7 ka, activity on the NW volcanic rift zone diminished and the intersection of the rift zones migrated slightly to the north. More recently, the triple rift geometry has been replaced at the surface by a N-S-trending rift zone which transects the volcano, and by E-W-trending en echelon fissure arrays on the western flank of the volcano. The NE rift zone has become completely inactive. This structural reconfiguration indicates weakening of the western flank of the volcano. The most recent eruption near the summit of the Cumbre Vieja, that of 1949, was accompanied by development of a west facing normal fault system along the crest of the volcano. The geometry of this fault system and the timing of its formation in relation to episodes of vent opening during the eruption indicate that it is not the surface expression of a dyke. Instead, it is interpreted as being the first surface rupture along a developing zone of deformation and seaward movement within the western flank of the Cumbre Vieja: the volcano is therefore considered to be at an incipient stage of flank instability. Climatic factors or strain weakening along the Cumbre Nueva collapse structure may account for the recent development of this instability.

  2. 1994 Volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

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

    1995-01-01

    During 1994, the Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, or false alarms at nine volcanic centers-- Mount Sanford, Iliamna, the Katmai group, Kupreanof, Mount Veniaminof, Shishaldin, Makushin, Mount Cleveland and Kanaga (table 1). Of these volcanoes, AVO has a real time, continuously recording seismic network only at Iliamna, which is located in the Cook Inlet area of south-central Alaska (fig. 1). AVO has dial-up access to seismic data from a 5-station network in the general region of the Katmai group of volcanoes. The remaining unmonitored volcanoes are located in sparsely populated areas of the Wrangell Mountains, the Alaska Peninsula, and the Aleutian Islands (fig. 1). For these volcanoes, the AVO monitoring program relies chiefly on receipt of pilot reports, observations of local residents and analysis of satellite imagery.

  3. Volcanoes

    MedlinePLUS

    ... by authorities and evacuate immediately from the volcano area to avoid flying debris, hot gases, lateral blast and lava flow. Be aware of mudflows . The danger from a mudflow increases near stream channels and with ... and low-lying areas. Remember to help your neighbors who may require ...

  4. 75 FR 7403 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Trawl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-19

    ...Islands Trawl Limited Access Fishery in the C. opilio Bycatch Limitation Zone of the Bering...pelagic trawl gear for walleye pollock, in the C. opilio bycatch limitation zone (COBLZ...exceeding the 2010 COBLZ bycatch allowance of C. opilio specified for the BSAI trawl...

  5. Geothermal resource assessment in the Aleutian Islands and Alaska peninsula: Quarterly progress report, January 1--March 30, 1989

    SciTech Connect

    Turner, D.L.; Nye, C.J.

    1989-03-30

    In this report the authors have now completed dating work on 20 rock samples. Analytical results for the dated samples are given in the enclosed table. The results are generally in good agreement with observed stratigraphic relationships and provide a well-constrained time framework for the eruptive history of this volcanic area. The argon extraction and potassium analyses are completed and the argon sample is awaiting mass spectrometry. In addition to documenting the eruptive history of Umnak volcanoes, the K-Ar ages will provide a time framework for the chemical evolution of the magmatic system, when combined with the rock chemistry analyses presently in progress at U.C., Santa Cruz. 1 tab.

  6. CO2 degassing at Papandayan and Kelud volcanoes, Java island, Indonesia

    NASA Astrophysics Data System (ADS)

    Mazot, A.; Bernard, A.

    2003-04-01

    Papandayan volcano (2665 m a.s.l) is located in the western part of the island of Java. The last magmatic eruption of this volcano occurred in 1772. At that time, the NE sector of the volcano collapsed, producing a large avalanche of debris and creating a horseshoe shaped crater. The most recent activity of Papandayan occurred in November 2002 when the volcano erupted ash clouds to altitudes of about 5 km. Before this event, the volcano was in a state of passive degassing with solfatara, sulfur-pools and hot springs. Since 1994, the geochemistry of these hot springs is monitored. These springs are acid sulfate-chloride waters with pH between 1.5 and 2.5. Sulfur isotopic composition (delta 34: 8-14.5 per mil) clearly suggest the injection of magmatic volatiles (SO2) to the hydrothermal system present at depth.A survey of diffuse CO2 degassing using the accumulation chamber method was performed in August 2001. 420 uniformly distributed points were measured in the main crater (Kawah Emas) covering an area of 58,000 m2. At least, two distinct populations of values are present. Diffuse CO2 degassing show a wide range of values from background values up to fluxes as high as 6,190 g/m2/day. The total degassing flux of CO2 estimated for this area is 7,410 t/year. This survey was completed in September 2002 with measurements of soil CO2 concentrations (at 50 cm depth). Concentrations as high as 30 vol. % were measured in some areas and clearly revealed the position of active faults on the crater floor. Kelud volcano (1650 m a.s.l.) is located in the eastern part of Java island and contains a crater lake. The Kelud historical eruption consisted mainly of pyroclastic flow and surges. Kelud volcano is known for its devastating lahars and a system of drainage was build in 1920 in order to keep the volume of the lake to 2 million m3.The last magmatic eruption occurred in 1990. Periodical geochemical surveys were carried out at the lake waters since 1993 to understand the hydrothermal system of this volcano. The lake contains near neutral waters with a pH of 6. In July 2001, we conducted a preliminary CO2 survey on the lake to measure the quantities of CO2 released from the lake surface to the atmosphere. The total flux of CO2 emitted by the lake surface is estimated at 28,400 t/year. A second survey was carried out in September 2002 and showed a significant decrease in CO2 flux to 19,700 t/year. This decrease in CO2 follow a net decrease in the input of hot fluids in the crater lake where the measured temperatures dropped from 42 °C in July 2001 to 33 °C in September 2002.

  7. 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.

  8. Living on the edge: Volcanic edifice failures along the north edge of the Aleutian Ridge

    NASA Astrophysics Data System (ADS)

    Coombs, M. L.; White, S.; Scholl, D. W.; Yogodzinski, G. M.

    2005-12-01

    Many Quaternary volcanoes in the Aleutian Island arc show evidence for catastrophic collapse and subsequent debris avalanche deposition on the seafloor. Active volcanoes in the central and western portions of the arc (177°E to 175°W) sit atop the northern edge of the ~4000 m-high Aleutian Ridge, constructed by arc volcanism starting at ~40 ma. This ridge drops off steeply to the north, providing significant runout potential for debris avalanches that flow into the Bering Sea. Reconnaissance studies have found subaerial evidence for large-scale collapse events at many of the volcanically active islands. The position of the Quaternary stratocones relative to the edge of the Aleutian ridge apparently controls their likelihood for collapse. Based on the absence of large pyroclastic sheets on the best-studied islands, most collapses were not accompanied by large-scale explosive eruptions, and thus were likely driven by gravitational failure instead of magmatic injection and caldera formation. GLORIA sidescan sonar data collected in the 1980s image hummocky debris on the seafloor north of several islands, notably Kiska, Gareloi, Tanaga, Kanaga, and Great Sitkin. Multibeam and backscatter data, acquired during the summer of 2005 with the 30 kHz Simrad EM300 system, corroborate the slide profile of several deposits first imaged by GLORIA. A debris avalanche deposit north of Kiska Island (177.6°E, 52.1°N), mapped in the greatest detail, has a hummocky surface that extends 40 km from the north flank of the volcano and covers an area of ~380 km2. A 24-channel seismic profile across the short axis of the deposit documents a 500 m-thick, chaotic unit that appears to have either cut into or disturbed a sequence of well-bedded sediments. Despite its thickness, the chaotic unit has only a few tens of meters of surface elevation above the surrounding seafloor. The volume of the debris-avalanche deposit could be as much as 190 km3. This suggests that estimating volumes solely by bathymetric data may underestimate total volumes of debris deposition in areas of easily eroded/deformed sedimentary sequences.

  9. ECHEYDE. Teide volcano and protohistoric Guanche settlements of Tenerife, Canary islands

    NASA Astrophysics Data System (ADS)

    Ilaria Pannaccione Apa, Maria; Barrera Rodriguez, Sergio; Fabrizia Buongiorno, Maria

    2010-05-01

    The volcanic origin and activity of the Canary island territory represent one of inhabitants growing factors of the along the recent geology, besides, the rich land fertility due to lava flows, was one of the reasons of their colonization by guanche culture. In general their social structure, based on chiefdom, as the Menceyatos, poor on technologies and strictly related to natural resources, could be considered as a real winning survival strategy face to an active volcanic island. The locational analysis carried out in this brief study shows that the western menceyatos were almost populated despite the possible high risks resulting from eruptions, landslides and lava flows. On the contrary, it seems clear that there was a total adaptation to the landscape, given by the high proportion of occupations in cave. Resilient mechanisms were probably transmitted during local assemblies, as a common strategy to face the events, despite the Spanish chronicles didn't inform of any particular guanche cultural tradition associated with Teide volcano and related hazards. The volcanic eruptions with low explosive features during last 10.000 years did not caused major cultural changes, whereas large ash falls produced a real damages with the consequence of human displacements along the limited island territories. [Canary Islands, Guanche, Volcanic Activity, Resilience

  10. Chikurachki Volcano

    Atmospheric Science Data Center

    2013-04-16

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

  11. ASTER-SRTM Perspective of Mount Oyama Volcano, Miyake-Jima Island, Japan

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Mount Oyama is a 820-meter-high (2,700 feet) volcano on the island of Miyake-Jima, Japan. In late June 2000, a series of earthquakes alerted scientists to possible volcanic activity. On June 27, authorities evacuated 2,600 people, and on July 8 the volcano began erupting and erupted five times over that week. The dark gray blanket covering green vegetation in the image is the ash deposited by prevailing northeasterly winds between July 8 and 17. This island is about 180 kilometers (110 miles) south of Tokyo and is part of the Izu chain of volcanic islands that runs south from the main Japanese island of Honshu. Miyake-Jima is home to 3,800 people. The previous major eruptions of Mount Oyama occurred in 1983 and 1962, when lava flows destroyed hundreds of houses. An earlier eruption in 1940 killed 11 people.

    This image is a perspective view created by combining image data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's Terra satellite with an elevation model from the Shuttle Radar Topography Mission (SRTM). Vertical relief is exaggerated, and the image includes cosmetic adjustments to clouds and image color to enhance clarity of terrain features.

    The ASTER instrument is a cooperative project between NASA, JPL, and the Japanese Ministry of International Trade and Industry.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

    Size: Island is approximately 8 kilometers (5 miles) in diameter Location: 34.1 deg. North lat., 139.5 deg. East lon. Orientation: View toward the west-southwest. Image Data: ASTER visible and near infrared Date Acquired: February 20, 2000 (SRTM), July 17, 2000 (ASTER)

  12. Off-ridge alkaline magmatism and seamount volcanoes in the Masirah island ophiolite, Oman

    NASA Astrophysics Data System (ADS)

    Meyer, J.; Mercolli, I.; Immenhauser, A.

    1996-12-01

    The Masirah ophiolite offers an unique opportunity to study well preserved small seamount structures. Obducted seamounts have not been described up to now, and from the present-day ocean floor they are almost exclusively known from bathymetric studies. The thin oceanic crust of the Masirah ophiolite was formed at a ridge-transform intersect in Upper Jurassic time. It was overprinted and reworked by a major intra-oceanic tectono-magmatic event at mid-Cretaceous time, that has been well dated owing to the presence of interstratified sedimentary rocks (late Hauterivian to early Barremian, c. 130-125 Ma). This mid-Cretaceous magmatism produced alkaline volcanic rocks ranging in chemistry from alkalibasalts to rhyolites. Volcanism occurred in a NW-SE extensional regime. Small, elongate submarine volcano structures (seamounts) developed within widespread alkalibasaltic pillow lava and pillow breccia deposits, which are interfingered with deep-marine pelagic sediments. The volcanoes reached a maximum of a few kilometres in diameter and a few hundred metres in height. The seamounts are built up of basic to acid subvolcanic stock- or sheet-like intrusions, several generations of dikes, vent agglomerates and pyro- to epiclastic deposits. The latter range from coarse breccias to finely stratified lapilli and record explosive volcanism in a deep marine environment. In the magma chambers under the volcanoes local differentiations to trachytic and rhyolitic members took place. The alkaline rocks show a pronounced ocean island basalt (OIB) character indicating the considerable contribution of a mantle plume source (hotspot). As cause of the volcanism we propose a combination of original transform setting followed by drift past the Marion hotspot during the major plate tectonic reorganization between Greater India, Madagascar and Africa starting in mid-Cretaceous time.

  13. Pyroclastic density currents at Stromboli volcano (Aeolian Islands, Italy): a case study of the 1930 eruption

    NASA Astrophysics Data System (ADS)

    Di Roberto, A.; Bertagnini, A.; Pompilio, M.; Bisson, M.

    2014-06-01

    Pyroclastic density currents (PDC) related to paroxysmal eruptions have caused a large number of casualties in the recent history of Stromboli. We combine here a critical review of historical chronicles with detailed stratigraphic, textural, and petrographic analyses of PDC deposits emplaced at Stromboli over the last century to unravel the origin of currents, their flow mechanism and the depositional dynamics. We focus on the 1930 PDC as they are well described in historical accounts and because the 1930 eruption stands as the most voluminous and destructive paroxysm of the last 13 centuries. Stromboli PDC deposits are recognizable from their architecture and the great abundance of fresh, well-preserved juvenile material. General deposit features indicate that Stromboli PDC formed due to the syn-eruptive gravitational collapse of hot pyroclasts rapidly accumulated over steep slopes. Flow channelization within the several small valleys cut on the flanks of the volcano can enhance the mobility of PDC, as well as the production of fine particles by abrasion and comminution of hot juvenile fragments, thereby increasing the degree of fluidization. Textural analyses and historical accounts also indicate that PDC can be fast (15-20 m/s) and relatively hot (360-700 °C). PDC can thus flow right down the slopes of the volcano, representing a major hazard. For this reason, they must be adequately taken into account when compiling risk maps and evaluating volcanic hazard on the Island of Stromboli.

  14. Deposits related to degradation processes on Piton des Neiges Volcano (Reunion Island): overview and geological hazard

    NASA Astrophysics Data System (ADS)

    Bret, Laurent; Fevre, Yannick; Join, Jean-Lambert; Robineau, Bernard; Bachelery, Patrick

    2003-04-01

    Piton des Neiges (PN) Volcano on Reunion Island offers a rare opportunity to study deposits related to degradation processes in a deeply eroded oceanic shield volcano. Both the inner parts and flanks reveal a large amount of resedimented volcaniclastic material, including extensive debris avalanche deposits. PN litho-structural units, first studied by Upton and Wadsworth [1965, Philos. Trans. R. Soc. Lond., A 271, pp. 105-130], are re-examined. This review highlights the importance of long volcanic repose periods and erosion processes during PN history. volcaniclastic deposits have been studied in the field in order to evaluate the spatial and temporal distribution of the three main types of PN degradation processes. The deposits of these processes have been classified into: (1) talus, (2) mudflow and debris flow, and (3) debris avalanche. Lithology, frequency and estimated volumes of each deposit type imply that the structural evolution of PN can be considered in terms of the competition between the volcanic productivity and the degradation and erosion processes. The occurrence of huge catastrophic avalanches produced by flank failure is convincingly linked to the basaltic activity of PN, which implies a very low risk at present. On the contrary, mudflows and debris flows pose an important risk due to the high population density focussed around the basin outlets. Moreover, if smaller debris avalanches can occur in the cirques of PN, another major risk must be evaluated.

  15. Identifying rift zones on volcanoes: an example from La Réunion island, Indian Ocean

    NASA Astrophysics Data System (ADS)

    Bonali, Fabio Luca; Corazzato, Claudia; Tibaldi, Alessandro

    2011-04-01

    We describe a methodology for identifying complex rift zones on recent or active volcanoes, where structures hidden by recent deposits and logistical conditions might prevent carrying out detailed fieldwork. La Réunion island was chosen as a test-site. We used georeferenced topographic maps, aerial photos and digital terrain models to perform a statistical analysis of several morphometric parameters of pyroclastic cones. This provides a great deal of geometric information that can help in distinguishing the localisation and orientation of buried magma-feeding fractures, which constitute the surface expression of rift zones. It also allowed the construction of a complete GIS database of the pyroclastic cones. La Réunion is a perfect example where past and active volcanic rift zones are mostly expressed by clusters of monogenic centres. The data has been validated in the field and compared and integrated with the distribution and geometry of dyke swarms. Results show the presence of several main and secondary rift segments of different ages, locations and orientations, whose origin is discussed considering regional tectonics, local geomorphology, and volcano deformation.

  16. The role of dome intrusions and flank spreading in the morphology of Teide volcano (Canary Islands)

    NASA Astrophysics Data System (ADS)

    Marquez, A.; Herrera, R.; Duvert, A.; Gómez-de la Peña, L.; Granja Bruña, J.; Llanes Estrada, M.; Van Wyk de Vries, B.

    2011-12-01

    Teide (Tenerife) is the only active stratovolcano in the Canary Islands. Two main overlapping vents (Teide and Pico Viejo) form an edifice 8 x 5 km wide and 1300 m high. Continuous fumarolic activity has been reported from the 15th century to the present day, although the last eruption from the summit was in 663-943 AD, forming the large Lavas Negras flow field. The morphology of Teide volcano shows a number of enigmatic features: 1) the two large "bulges" on the ENE and NW flanks, which produce a characteristic concave-convex profile; and 2) a flat summit area delimited by several inward dipping escarpments. This morphology of the volcano has been interpreted to be due to asymmetric deformation by flank spreading over a weak hydrotermally-altered core. However, the role of deformation is debatable, since several authors interpreted the summit area scarps as walls of old summit craters and the two bulges as old flank vents, with all such structures partially covered by the Lavas Negras. In order to test these contrasting hypotheses we have combined a morphological study of the eastern flank and summit area of Teide volcano using high resolution DEMs and aerial orthophotographs, with a detailed field work. At the volcano eastern flank we have mapped several lava dome features (most previously unrecognized) at altitudes between 2950 and 3160 m a.s.l. indicating that dome intrusions have not been restricted to the base of the edifice as previously thought. However, we have also observed in several points of the eastern flank that the slope change knickpoint is not related to the presence of any flank vent. In addition, we found field evidence of a possible shallow cryptodome intrusion below the flat summit area at 3500 m a.s.l.: a bulged convex area 150x100 m wide, delimited by a prominent slope break onto a very flat area, with a topographic scarp related to a possible inward-dipping fault. The only active fumarolic field outside Teide crater is located along this proposed fault zone, indicating that it could be connected to the intrusion at depth, forming an easy path for magma degassing, as it has been seen in analogue models of cryptodome intrusion. We also observed that the two main inward dipping scarps that delimitates the flat summit area to the north and south do not show fumarolic activity and have no bulged convex profile in their footwall. Our observations show that the role of intrusive activity in Teide volcano could have been much more important that previously recognized, and that the edifice could have suffered deformation in the past due to the intrusion of shallow cryptodomes. However, not all the morphological features of the edifice can be explained by this process, and therefore we consider that deformation of Teide volcano by flank spreading over a weak hydrothermal core is a plausible hypothesis that should still be explored due to its important implications for volcano instability.

  17. Coccidia of Aleutian Canada geese

    USGS Publications Warehouse

    Greiner, E.C.; Forrester, Donald J.; Carpenter, J.W.; Yparraguirre, D.R.

    1981-01-01

    Fecal samples from 122 captive and 130 free-ranging Aleutian Canada geese (Branta canadensis leucopareia) were examined for oocysts of coccidia. Freeranging geese sampled on the spring staging ground near Crescent City, California were infected with Eimeria hermani, E. truncata, E. magnalabia, E. fulva, E. clarkei and Tyzzeria parvula. Except for E. clarkei, the same species of coccidia were found in geese on their breeding grounds in Alaska. Most of the coccidial infections in captive geese from Amchitka Island, Alaska and Patuxent Wildlife Research Center, Maryland, consisted of Tyzzeria.

  18. Pacific Basin tsunami hazards associated with mass flows in the Aleutian arc of Alaska

    USGS Publications Warehouse

    Waythomas, Christopher F.; Watts, Philip; Shi, Fengyan; Kirby, James T.

    2009-01-01

    We analyze mass-flow tsunami generation for selected areas within the Aleutian arc of Alaska using results from numerical simulation of hypothetical but plausible mass-flow sources such as submarine landslides and volcanic debris avalanches. The Aleutian arc consists of a chain of volcanic mountains, volcanic islands, and submarine canyons, surrounded by a low-relief continental shelf above about 1000–2000 m water depth. Parts of the arc are fragmented into a series of fault-bounded blocks, tens to hundreds of kilometers in length, and separated from one another by distinctive fault-controlled canyons that are roughly normal to the arc axis. The canyons are natural regions for the accumulation and conveyance of sediment derived from glacial and volcanic processes. The volcanic islands in the region include a number of historically active volcanoes and some possess geological evidence for large-scale sector collapse into the sea. Large scale mass-flow deposits have not been mapped on the seafloor south of the Aleutian Islands, in part because most of the area has never been examined at the resolution required to identify such features, and in part because of the complex nature of erosional and depositional processes. Extensive submarine landslide deposits and debris flows are known on the north side of the arc and are common in similar settings elsewhere and thus they likely exist on the trench slope south of the Aleutian Islands. Because the Aleutian arc is surrounded by deep, open ocean, mass flows of unconsolidated debris that originate either as submarine landslides or as volcanic debris avalanches entering the sea may be potential tsunami sources. To test this hypothesis we present a series of numerical simulations of submarine mass-flow initiated tsunamis from eight different source areas. We consider four submarine mass flows originating in submarine canyons and four flows that evolve from submarine landslides on the trench slope. The flows have lengths that range from 40 to 80 km, maximum thicknesses of 400–800 m, and maximum widths of 10–40 km. We also evaluate tsunami generation by volcanic debris avalanches associated with flank collapse, at four locations (Makushin, Cleveland, Seguam and Yunaska SW volcanoes), which represent large to moderate sized events in this region. We calculate tsunami sources using the numerical model TOPICS and simulate wave propagation across the Pacific using a spherical Boussinesq model, which is a modified version of the public domain code FUNWAVE. Our numerical simulations indicate that geologically plausible mass flows originating in the North Pacific near the Aleutian Islands can indeed generate large local tsunamis as well as large transoceanic tsunamis. These waves may be several meters in elevation at distal locations, such as Japan, Hawaii, and along the North and South American coastlines where they would constitute significant hazards.

  19. Problems in Using Underground Water Temperatures in Volcanic Surveillance: the Case of Volcano Island (Eolian Islands, Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Madonia, P.; Capasso, G.; Favara, R.

    2002-12-01

    Measuring underground water temperatures in a network of wells, together with many other geochemical and geophysical data, is a useful tool in medium-long term surveillance of active volcanic areas. The study case here presented deals with Volcano Island (Eolian Islands, Sicily, Italy). About 20 years of observations are presented; they have been acquired either during spot campaigns, every 1-3 months, either by continuous monitoring (sampling period of 2 hours). Although the interested active volcanic area has an extension of few square kilometers, data analysis pointed out a surprising variability in space and time of the information acquired, and in particular: a) Monthly temperature variations show a frequency related to the hydrological cycle, except some wells located in a piezometric high (Camping Sicilia well) or in distal positions respect to the La Fossa Crater (EAS and Discarica wells). b) Some wells subjected to continuous monitoring, affected (Le Calette) or not (Camping Sicilia) by seasonal variations, show high frequency (from few hours to few days) pulsation of several Celsius degrees. The above mentioned variations are sometimes related to seismic events (Gulf of Patti earthquakes, April 2002). c) Water table elevations from sea level, measured at the same time of temperature, highlight the presence of some wells (EAS, Casamento) where the piezometric surface is normally below the sea, despite they are very near to the coast line. The elements above discussed point out the presence of a complex multi-layered aquifer, with very different interactions between fresh, sea and volcanic waters, that are reflected in space and time variations of measured B.H.T. values. The implementation of an accurate hydrogeological model is then to be considered as preventive and fundamental in order to correctly design a surveillance activity based on underground fluids monitoring in this area.

  20. Volcano-tectonic evolution of Santa Maria Island: implications for the Nubia-Eurasia plate boundary in the Azores

    NASA Astrophysics Data System (ADS)

    Sibrant, A.; Hildenbrand, A.; Marques, F. O.; Costa, A. C.

    2013-12-01

    Santa Maria is a key island in the Azores because it has unique position and age: it sits near the eastern portion of an extinct plate boundary, the East Azores Fracture Zone, and ca. 100 km to the west of the junction between the active Terceira Rift and the Gloria fault. It is by far the oldest island in the archipelago, thus recording a story that no other island in the Azores can tell. From morphologic, stratigraphic and new high resolution K-Ar dating, we show that the volcano-tectonic evolution of Santa Maria is marked by the fast construction of two shield volcanoes separated by a volcano-sedimentary complex. The youngest age we measured for the older construction phase is 4.32 × 0.06 Ma. The oldest age of the younger phase is 4.02 × 0.06 Ma, whereas the youngest age we obtained in Santa Maria is 2.84 × 0.04 Ma. From geophysical, bathymetric and our new geochronological data, we propose that the lineament materialized by the S. Jorge graben in the northwest and Santa Maria Island in the southeast is an intermediate rift, which developed between the East Azores Fracture Zone and the Terceira Rift during migration of the Nubia-Eurasia plate boundary to the northeast. From our new data, the southern part of this intermediate Rift was active between at least ca. 6 Ma and 2.8 Ma.

  1. Satellite and ground observations of the June 2009 eruption of Sarychev Peak volcano, Matua Island, Central Kuriles

    NASA Astrophysics Data System (ADS)

    Rybin, Alexander; Chibisova, Marina; Webley, Peter; Steensen, Torge; Izbekov, Pavel; Neal, Christina; Realmuto, Vince

    2011-11-01

    After 33 years of repose, one of the most active volcanoes of the Kurile island arc—Sarychev Peak on Matua Island in the Central Kuriles—erupted violently on June 11, 2009. The eruption lasted 9 days and stands among the largest of recent historical eruptions in the Kurile Island chain. Satellite monitoring of the eruption, using Moderate Resolution Imaging Spectroradiometer, Meteorological Agency Multifunctional Transport Satellite, and Advanced Very High Resolution Radiometer data, indicated at least 23 separate explosions between 11 and 16 June 2009. Eruptive clouds reached altitudes of generally 8-16 km above sea level (ASL) and in some cases up to 21 km asl. Clouds of volcanic ash and gas stretched to the north and northwest up to 1,500 km and to the southeast for more than 3,000 km. For the first time in recorded history, ash fall occurred on Sakhalin Island and in the northeast sector of the Khabarovsky Region, Russia. Based on satellite image analysis and reconnaissance field studies in the summer of 2009, the eruption produced explosive tephra deposits with an estimated bulk volume of 0.4 km3. The eruption is considered to have a Volcanic Explosivity Index of 4. Because the volcano is remote, there was minimal risk to people or infrastructure on the ground. Aviation transport, however, was significantly disrupted because of the proximity of air routes to the volcano.

  2. GPS application to the study of ground deformation in the volcano tectonic systems of the Terceira Island (Azores) - preliminary results

    NASA Astrophysics Data System (ADS)

    Rodrigues, Rita; Ferreira, Teresa; Okada, Jun; Trota, António; Gaspar, João.

    2010-05-01

    The Azores Archipelago comprises nine volcanic islands, located where the Eurasian, American and African plates meet. Due to this complex tectonic setting seismic and volcanic activities are frequent in the archipelago. Since its settlement, in the 15th century, several volcanic eruptions and destructive earthquakes have been reported causing thousands of deaths and severe damages. Last eruption in the Azores occurred at sea, from 1998 until 2001, almost 10 km W of Serreta (Terceira Island). Ground deformation due to volcanic magma intrusion is recognised as an important precursor of eruptive activity at a volcano. The GPS is ideally suited for this application by being able to measure three-dimensional coordinate changes of the monitoring points over time. A comprehensive volcano-monitoring program should include techniques to measure surface deformations in order to contribute to a complete characterization of volcanic behaviour. Conventional modern geodetic techniques provide useful tools for the acquisition of discrete or continuous ground-deformation data. In the scope of the Azores seismovolcanic monitoring programme a geodetic network was implemented in Terceira Island. Forty geodetic benchmarks which include two permanent stations distributed according to the main volcanic and tectonic structures in the island. In the last six years five survey-mode campaigns have been performed, and the absolute velocities and internal deformations of the island have been evaluated from 2003 to 2009. Bernese 5.0 Software was used for GPS data processing and estimation of station coordinates and velocities for the periods. Obtained velocity fields considering S. Miguel Island fixed shows subsidence over all of the island and oblique displacement along Terceira Rift. This supports the existence of the shear zone between S. Miguel and Terceira Islands. Regarding internal deformations in the island, the lower magnitude of horizontal velocities indicate apparently stable regime which corresponds to the absence of major seismic events during the periods in the island. However, comparing with its surroundings, more prominent subsidence can be recognized in the middle part of the island where the active volcanic systems exist, such as Pico Alto, the central caldera Guiherme Moniz, and the Fissural Zone which has the most recent eruptive centers on land in Terceira (1761 AD). The analysis of GPS data over 6 years revealed time-dependent process of ground subsidences in the volcano tectonic systems of Terceira Island.

  3. Two Decades of Degassing at Kilauea Volcano, Hawai`i: Perspectives on Island Impacts

    NASA Astrophysics Data System (ADS)

    Elias, T.; Sutton, A. J.

    2003-12-01

    The ongoing eruption of Kilauea provides an opportunity to examine how volcanic emissions impact the natural and human environment of the island of Hawai`i. Kilauea has released ˜ 13 megatons of SO2 gas into the troposphere since the current eruption began in 1983, more than any single anthropogenic source in the U.S. During prevailing trade wind conditions, measurements of SO2 gas, aerosol mass, and aerosol acidity downwind of Kilauea document the conversion of SO2 to acid aerosol as the plume propagates to the leeward side of the island. Lidar measurements suggest a gas-to-particle conversion rate (t1/2) of 6 hours. When trade winds are disrupted, ambient SO2 and particle measurements in Hawai`i Volcanoes National Park have shown episodes of particle concentrations of ˜ 100 ? g/m3 and SO2 concentrations in excess of 4000 ppb. Federal health standards and WHO guidelines for SO2 have been exceeded repeatedly at this near-source location. Documented effects from volcanic emissions on the island of Hawai`i include the rapid corrosion of metal objects, degradation of domestic water quality, agricultural crop damage, and adverse impacts on human respiratory and pulmonary function. Other impacts may include decreases in local rainfall and increased mortality of asthmatics. For the period 1986 to 1993, after the eruption became continuous, deaths from asthma on the island of Hawai`i increased by a factor of ten. Three current health studies seek to investigate the relationship between exposure to volcanic pollution and health effects. In addition to measuring gas and particle exposures, these studies examine lung development in children around the island, disease prevalence in adults residing in communities downwind of volcanic degassing sources, and acute effects in asthmatic children and healthy children and adults. In the absence of conclusive evidence linking exposure and health effects, the USGS, in collaboration with the National Park Service, has developed a real-time advisory for heavily visited park areas known to exceed U.S. Air Quality Standards. This color-coded system informs and advises park visitors and employees when ambient SO2 concentrations exceed predetermined levels.

  4. Construction and destruction rates of volcanoes within tropical environment: Examples from the Basse-Terre Island (Guadeloupe, Lesser Antilles)

    NASA Astrophysics Data System (ADS)

    Ricci, Julia; Lahitte, Pierre; Quidelleur, Xavier

    2015-01-01

    In order to better constrain the construction and the erosion rate affecting the volcanic island of Basse-Terre Island (Guadeloupe, F.W.I.), an enlarged K-Ar age dataset has been combined with reconstruction of the paleo-topography. Two different methods of interpolation of the present topography have been cross-checked to better support the erosion rates obtained and their associated uncertainties. The present study focusses on the Monts-Caraïbes volcanoes and on the main geomorphic feature of the Piton de Bouillante volcano, the Beaugendre Valley. The Monts-Caraïbes volcanoes were constructed in 83 kyr at a rate of 0.12 ± 0.04 km3/kyr. During the last 450 kyr, they have experienced an erosion rate of 610 ± 550 t/km2/yr. In the Piton de Bouillante volcano eleven new K-Ar ages have been obtained, constraining the duration of its volcanic activity between 880 ± 14 and 712 ± 12 ka, and involving a construction rate of 0.70 ± 0.20 km3/kyr. For this volcano, an erosion rate of 1220 ± 700 t/km2/yr has been obtained for the last 700 kyr. Our study also shows, based on the contemporaneity of the ages in the entire Beaugendre Valley added to the mean erosion rate of 1350 ± 550 t/km2/yr, that the flank collapse hypothesis cannot explain the formation of this valley. Finally, the similarity of the erosion rates computed for different locations of the Basse-Terre Island shows that the time-integrated erosion appears independent to the trade wind effect and suggests that the barrier effect due to the relief is not present here.

  5. Petroleum potential of volcanogenic and volcano-sedimentary rocks in ancient and recent island arcs: Caucasus, Komandorskie, and Kuril islands, eastern Kamchatka

    SciTech Connect

    Levin, L.E. (VNIIZarubezhgeologia, Moscow (Russian Federation))

    1993-09-01

    In the Late Cretaceous-Eocene, subduction of the Tethys oceanic plate under the island arc of the lesser Caucasus contributed to the appearance of the special conditions favorable for petroleum occurrence: (1) tectono-magmatic destruction of the crust of the Transcaucasus median massif and formation of hydrocarbon traps of different types and origins, and (2) high heat flow lasting until the recent epoch. These led flow-intensive generation of hydrocarbons in the shallow-water sediments of the paleoshelf of the Transcaucasus massif and accumulation of hydrocarbons not only in the sedimentary but also in the volcanogenic and volcano-sedimentary reservoirs (Samgori-Patardzeuli, Muradhanly fields, etc.). At the end of the Oligocene, the geodynamic setting in the northwestern margins of the Pacific Ocean was mainly similar to that within the Transcaucasus median massif. At the end of Oligocene-Miocene, such conditions determined the tectono-magmatic destruction of the continental crust and formation of the series of interarc rifts. The main fields of Japan, with accumulations in the volcanogenic and volcano-sedimentary rocks, are concentrated here. Its analog is the rift located in the southern part of a single east Kuril basin, where petroleum occurrence is only inferred. In the separate troughs, the thickness of the volcano-sedimentary cover is 4-6 km. The stratigraphic section of the cover contains the volcanic and volcano-sedimentary sediments of the Neogene-Pleistocene. The studies of the sections of the Komandorskie islands, eastern Kamchatka, Kuril Islands, and western Sakhalin indicate that distribution of reservoirs depends on the stage of evolution of the rifts and adjacent island arcs.

  6. 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.

  7. Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan

    PubMed Central

    Uyeda, S.; Hayakawa, M.; Nagao, T.; Molchanov, O.; Hattori, K.; Orihara, Y.; Gotoh, K.; Akinaga, Y.; Tanaka, H.

    2002-01-01

    Significant anomalous changes in the ultra low frequency range (?0.01 Hz) were observed in both geoelectric and geomagnetic fields before the major volcano-seismic activity in the Izu Island region, Japan. The spectral intensity of the geoelectric potential difference between some electrodes on Niijima Island and the third principal component of geomagnetic field variations at an array network in Izu Peninsula started to increase from a few months before the onset of the volcano-seismic activity, culminating immediately before nearby magnitude 6 class earthquakes. Appearance of similar changes in two different measurements conducted at two far apart sites seems to provide information supporting the reality of preseismic electromagnetic signals. PMID:12032286

  8. Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan.

    PubMed

    Uyeda, S; Hayakawa, M; Nagao, T; Molchanov, O; Hattori, K; Orihara, Y; Gotoh, K; Akinaga, Y; Tanaka, H

    2002-05-28

    Significant anomalous changes in the ultra low frequency range (approximately 0.01 Hz) were observed in both geoelectric and geomagnetic fields before the major volcano-seismic activity in the Izu Island region, Japan. The spectral intensity of the geoelectric potential difference between some electrodes on Niijima Island and the third principal component of geomagnetic field variations at an array network in Izu Peninsula started to increase from a few months before the onset of the volcano-seismic activity, culminating immediately before nearby magnitude 6 class earthquakes. Appearance of similar changes in two different measurements conducted at two far apart sites seems to provide information supporting the reality of preseismic electromagnetic signals. PMID:12032286

  9. Deformation across the Alaska-Aleutian Subduction Zone near Kodiak

    USGS Publications Warehouse

    Savage, J.C.; Svarc, J.L.; Prescott, W.H.

    1999-01-01

    The Kodiak-Katmai geodetic array, nine monuments distributed along a profile trending north-northwestward across Kodiak Island and the Alaska Peninsula, was surveyed in 1993, 1995 and 1997 to determine the deformation at the Alaska-Aleutian subduction zone. Velocities on Kodiak Island measured relative to the stable North American plate decrease with distance from the Alaska-Aleutian trench (distance range 106 to 250 km), whereas no appreciable deformation was measured on the Alaska Peninsula (distances 250 to 370 km from the trench). The measured deformation is reasonably well predicted by the conventional dislocation representation of subduction with the model parameters determined independently (i.e., not simply by fitting the observations). The deformation of Kodiak Island is in striking contrast to the very minor deformation measured in the similarly situated Shumagin Islands, 450 km southwest of Kodiak along the Alaska-Aleutian trench.

  10. Application of emulsion imaging system for cosmic-ray muon radiography to explore the internal structure of Teide and Cumbre Vieja volcanoes in the Canary Islands, Spain

    NASA Astrophysics Data System (ADS)

    Hernández, Iñigo; Hernández, Pedro; Pérez, Nemesio; Tanaka, Hiroyuki; Miyamoto, Seygo; Barrancos, José; Padrón, Eleazar

    2013-04-01

    The internal structure of volcanoes, especially in their up per part, is product of past eruptions. Therefore, the knowledge of the internal structure of a volcano is of great importance for understanding its behaviour and to forecast the nature and style of the next eruptions. For these reasons, during past years scientists have made a big effort to investigate the internal structure of the volcanoes with different geophysical techniques, including deep drilling, passive and active seismic tomography, geoelectrics and magnetotellurics and gravimetry. One of the limits of conventional geophysical methods is the spatial resolution, which typically ranges between some tens of meters up to 1 km. In this sense, the radiography of active volcanoes based on natural muons, even if limited to the external part of the volcano, represents an important tool for investigating the internal structure of a volcano at higher spatial resolution (Macedonio and Martini, 2009). Moreover, muon radiography is able to resolve density contrasts of the order of 1-3%, significantly greater than the resolution obtained with conventional methods. As example, the experiment of muon radiography carried out at Mt. Asama volcano by Tanaka et al., 2007, allowed the reconstruction of the density map of the cone and detection of a dense region that corresponds to the position and shape of a lava deposit created during the last eruption in 2004. In the framework of a research project financed by the Canary Agency of Research, Innovation and Information Society, we will implement muon measurements at Teide volcano in Tenerife Island and Cumbre Vieja volcano in La Palma Island, Canary Islands, to radiographically image the subsurface structure of these two volcanic edifices. The data analysis will involve the study both of the shallow structure of both volcanoes and of the requirements for the implementation of the muon detectors. Both Cumbre Vieja and Teide are two active volcanoes that arouse great interest in the scientific community and society due to their volcanic features and specific hazards associated with volcanic activity.

  11. On the time-scales of magmatism at island-arc volcanoes.

    PubMed

    Turner, S P

    2002-12-15

    Precise information on time-scales and rates of change is fundamental to an understanding of natural processes and the development of quantitative physical models in the Earth sciences. U-series isotope studies are revolutionizing this field by providing time information in the range 10(2)-10(4) years, which is similar to that of many modern Earth processes. I review how the application of U-series isotopes has been used to constrain the time-scales of magma formation, ascent and storage beneath island-arc volcanoes. Different elements are distilled-off the subducting plate at different times and in different places. Contributions from subducted sediments to island-arc lava sources appear to occur some 350 kyr to 4 Myr prior to eruption. Fluid release from the subducting oceanic crust into the mantle wedge may be a multi-stage process and occurs over a period ranging from a few hundred kyr to less than one kyr prior to eruption. This implies that dehydration commences prior to the initiation of partial melting within the mantle wedge, which is consistent with recent evidence that the onset of melting is controlled by an isotherm and thus the thermal structure within the wedge. U-Pa disequilibria appear to require a component of decompression melting, possibly due to the development of gravitational instabilities. The preservation of large (226)Ra disequilibria permits only a short period of time between fluid addition and eruption. This requires rapid melt segregation, magma ascent by channelled flow and minimal residence time within the lithosphere. The evolution from basalt to basaltic andesite probably occurs rapidly during ascent or in magma reservoirs inferred from some geophysical data to lie within the lithospheric mantle. The flux across the Moho is broadly andesitic, and some magmas subsequently stall in more shallow crustal-level magma chambers, where they evolve to more differentiated compositions on time-scales of a few thousand years or less. PMID:12626270

  12. 78 FR 57097 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-17

    ...the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian Islands...SUMMARY: NMFS is prohibiting retention of sharks in the Bering Sea and Aleutian Islands...2013 total allowable catch (TAC) of sharks in the BSAI has been reached....

  13. 76 FR 59924 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    ...the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian Islands...SUMMARY: NMFS is prohibiting retention of sharks in the Bering Sea and Aleutian Islands...2011 total allowable catch (TAC) of sharks in the BSAI has been reached....

  14. 76 FR 17360 - Fisheries of the Exclusive Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-29

    ...the Exclusive Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian Islands...to the initial total allowable catch of octopus in the Bering Sea and Aleutian Islands...initial total allowable catch (ITAC) of octopus in the BSAI was [[Page 17361

  15. Ground deformation associated with the eruption of Lumpur Sidoardjo mud volcano, eastern Java island

    NASA Astrophysics Data System (ADS)

    Aoki, Yosuke; Purnama Sidiq, Teguh

    2013-04-01

    Mud volcanism is a process that drives the extrusion of materials in the sediment to the surface. While it shares common features with magmatic eruptions; for example, eruption of mud volcanoes often results in elongated calderas and aligned vents. However, the mechanics of mud volcanism is not fully understood because of the rare occurrence. Here we take an advantage of observing ongoing eruption in Lumpur Sidoarjo (LUSI) mud volcano, eastern Java island, to gain insights into the mechanics of mud volcanism. LUSI has been erupting since May 2006 and released more than 12 million cubic meter of mud so far, buried some 20 square kilometers and forced 8000 people to evacuate. We delineated the temporal evolution of ground deformation from Synthetic Aperture Radar images taken from the ALOS satellite. We processed a total of 93 images from two ascending and three descending images between May 2006 and April 2011 using the StaMPS software (Hooper, GRL, 2008) to obtain the displacement time series of persistent scatterers. Although we were not able to obtain the time series in areas near the center of activity due to the lower coherence resulting from the mudflow, we observed an extension of line-of-sight (LOS) distance by a total of up to 200 millimeters within a few kilometers from the activity center from both ascending and descending images. This indicates that the deformation around the center of activity is dominated by subsidence. We also found an area of subsidence with a similar or even larger rate extending to the west of the activity center. This indicates that the depressurization beneath the activity center is not the only mechanism to cause this eruption but we need to consider another source to explain the observed displacement field. We also found a LOS shortening to the north of the activity center only from ascending images. This indicates an uplift and westward displacement in this area. Despite the decreasing rate of gas emission, our time series analysis shows that the deformation is quasi-linear during the time of the analysis. This suggests that the source of deformation has been stationary over time and and also it will a take long time for this eruption to cease.

  16. Zn isotope compositions of the thermal spring waters of La Soufrière volcano, Guadeloupe Island

    NASA Astrophysics Data System (ADS)

    Chen, Jiu-Bin; Gaillardet, Jérôme; Dessert, Céline; Villemant, Benoit; Louvat, Pascale; Crispi, Olivier; Birck, Jean-Louis; Wang, Yi-Na

    2014-02-01

    To trace the sources and pathways of Zn in hydrothermal systems, the Zn isotope compositions of seventeen water samples from eight thermal springs and six gas samples from two fumaroles from La Soufrière, an active volcano on Guadeloupe Island (French West Indies, FWI), were analyzed using a method adapted for purifying Zn from Fe- and SO4-enriched thermal solutions. The fumaroles are enriched in Zn 100 to 8000 times compared to the local bedrock and have isotopic compositions (?66Zn values from +0.21‰ to +0.35‰) similar to or slightly higher than fresh andesite (+0.21‰). The enrichment of Zn in the thermal springs compared with the surface waters shows that Zn behaves as a soluble element during hydrothermal alteration but is significantly less mobile than Na. The ?66Zn values of most of the spring waters are relatively constant (approximately 0.70‰), indicating that the thermal springs from La Soufrière are enriched in heavy isotopes (i.e., 66Zn) compared to the host rocks (from -0.14‰ to +0.42‰). Only three thermal springs have lower ?66Zn values (as low as -0.43%). While the Zn in the fumaroles is essentially derived from magma degassing, which is consistent with a previous study on Merapi volcano (Toutain et al., 2008), we show that the Zn in the thermal springs is mainly derived from water-rock interactions. The 66Zn-enriched isotopic signature in most of the spring waters can be explained qualitatively by the precipitation at depth of sulfide minerals that preferentially incorporate the light isotopes. This agrees with the isotopic fractionation that was recently calculated for aqueous complexes of Zn. The few thermal springs with lower ?66Zn values also have low Zn concentrations, indicating the preferential scavenging of heavy Zn isotopes in the hydrothermal conduits. This study shows that unlike chemical weathering under surface conditions, hydrothermal alteration at high temperatures significantly fractionates Zn isotopes and enriches thermal waters in heavy Zn isotopes (e.g., 66Zn). Continental hydrothermal systems therefore constitute a source of heavy Zn isotopes to the oceans; this should be taken into account in the global oceanic budget of Zn.

  17. Ups and downs on spreading flanks of ocean-island volcanoes: Evidence from Mauna Loa and K?lauea

    NASA Astrophysics Data System (ADS)

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

    2003-10-01

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

  18. The Galápagos Islands seen from space: the contribution of Synthetic Aperture Radar Interferometry (InSAR) to volcano monitoring

    NASA Astrophysics Data System (ADS)

    Osmanoglu, B.; Baker, S.; Bagnardi, M.; Amelung, F.

    2010-12-01

    Although the Galápagos volcanoes are some of the most active volcanoes on Earth, because of their geographic isolation and the difficult working conditions they have been virtually unmonitored by geodetic methods until the last 18 years. The use of detailed Interferometric Synthetic Aperture Radar (InSAR) measurements of the surface deformation provides a unique opportunity to study magmatic processes in such a location. The phase difference (interferogram) of SAR images pairs for the same area acquired at different times, provides measurements of the ground deformation along the radar line-of-sight (LOS) with centimeter to millimeter accuracy. We use SAR data acquired over the Galápagos by the European Space Agency satellites ERS-1, ERS-2, ENVISAT and by the Canadian Space Agency satellite Radarsat-1, between 1992 and 2010. In order to obtain the temporal evolution of ground deformation at each volcano, we use the selected dataset and we apply the Small Baseline Subset (SBAS) method. We present SBAS displacement time-series for Wolf, Darwin, Fernandina, Alcedo, Sierra Negra and Cerro Azul, showing that all the six volcanoes that forms Fernandina and Isabela Islands have been actively deforming during the last eighteen years. We also identify and constrain some of the sources that generate the observed surface deformation by performing non-linear inversions in a homogeneous, isotropic, elastic half-space. With the frequent acquisitions of the ENVISAT satellite, we are able to study the evolution of the latest eruptions at Cerro Azul in 2008 and at Fernandina in 2009.

  19. Combining seismic and geochemical constraints on magmatic processes in the Aleutian arc (Invited)

    NASA Astrophysics Data System (ADS)

    Shillington, D. J.; Van Avendonk, H. J.; Behn, M. D.; Janiszewski, H. A.; Abers, G. A.; Kelemen, P. B.; Jagoutz, O. E.

    2013-12-01

    Seismic imaging provides one of the few constraints on the in situ structure and composition of island arc crust. Competing models for arc magmatic processes make different predictions for island arc structure, from lower crustal composition to the depth to crustal magma chambers. However, challenges of using seismic observations to constrain arc processes include the non-uniqueness of linking individual seismic attributes to composition and the paucity of observations worldwide. Here, we discuss the results, challenges and opportunities of seismic imaging of island arcs by discussing new and not-so-new seismic results from the Aleutian island arc, their relationship to other observations from this arc and comparisons with other oceanic island arcs worldwide. We will focus on ways to combine different types of data to extract better constraints than any single observation could provide in isolation. The Aleutian arc has a thick (>30 km) and mafic crust based on wide-angle seismic data from the central Aleutian island arc, tomography from local earthquakes, and receiver functions of widely spaced permanent seismic stations along the arc. Tomographic inversion of a sparse along-arc profile revealed that the lower crust here has notably high velocities (>7.3 km/s at depths of 20-35 km) and hinted at along-strike variations in velocity structure that related to the composition of surface volcanism. Receiver functions from a few stations also locally reveal intra-crustal conversions at 20-25 km that are consistent with a velocity step at the top of a mafic lower crust. However, Vp, alone, cannot uniquely differentiate between possible explanations for high-velocity lower crust. We present new constraints on lower crustal composition from average Vp/Vs based on sparse converted S-waves in wide-angle data. We find a low Vp/Vs of ~1.7-1.75 in the lower crust trenchward of the active arc (but within the arc platform). Using petrologic modeling, we show that no single composition is likely to explain the combination of high Vp and low Vp/Vs. Our preferred explanation is a combination of clinopyroxenite (~50-70%) and alpha-quartz bearing gabbros (~30-50%). This is consistent with Aleutian xenoliths and rocks in obducted arcs, and implies ~30-40% of the full Aleutian crust comprises ultramafic cumulates. An unexpected result is that small amounts of quartz can exert a strong influence on Vp/Vs in arc crust. At shallower levels, receiver function analysis also identifies a strong upper crustal conversion at ~10 km depth beneath Akutan, which we interpret as an upper crustal magma body. Variations in back azimuth and modeling indicate that it is best explained by a low velocity layer that extends below much of the island, and is more extensive than the eruptive edifice. These results are consistent with results from InSAR and lava geochemistry. To advance our understanding of magmatic processes in arcs, we require higher resolution imaging with diverse geophysical methods to constrain variations in the structure and composition and the distribution of magma chambers throughout the crust at the scale lengths of individual volcanoes. Additionally, closer integration of diverse seismic imaging studies (active-source refraction, receiver function, noise tomography) with each other and with petrological observations and models is essential for reducing ambiguity in interpreting composition from seismic attributes.

  20. Methods of InSAR atmosphere correction for volcano activity monitoring

    USGS Publications Warehouse

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

    2011-01-01

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

  1. Aseismic inflation of Westdahl volcano, Alaska, revealed by satellite radar interferometry

    USGS Publications Warehouse

    Lu, Z.; Wicks, C.; Dzurisin, D.; Thatcher, W.; Freymueller, J.T.; McNutt, S.R.; Mann, D.

    2000-01-01

    Westdahl volcano, located at the west end of Unimak Island in the central Aleutian volcanic arc, Alaska, is a broad shield that produced moderate-sized eruptions in 1964, 1978-79, and 1991-92. Satellite radar interferometry detected about 17 cm of volcano-wide inflation from September 1993 to October 1998. Multiple independent interferograms reveal that the deformation rate has not been steady; more inflation occurred from 1993 to 1995 than from 1995 to 1998. Numerical modeling indicates that a source located about 9 km beneath the center of the volcano inflated by about 0.05 km3 from 1993 to 1998. On the basis of the timing and volume of recent eruptions at Westdahl and the fact that it has been inflating for more than 5 years, the next eruption can be expected within the next several years.

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

    USGS Publications Warehouse

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

    2008-01-01

    As magma moves toward the surface, it interacts with anything in its path: hydrothermal systems, cooling magma bodies from previous eruptions, and (or) the surrounding 'country rock'. Magma also undergoes significant changes in its physical properties as pressure and temperature conditions change along its path. These interactions and changes lead to a range of geophysical and geochemical phenomena. The goal of volcano monitoring is to detect and correctly interpret such phenomena in order to provide early and accurate warnings of impending eruptions. Given the well-documented hazards posed by volcanoes to both ground-based populations (for example, Blong, 1984; Scott, 1989) and aviation (for example, Neal and others, 1997; Miller and Casadevall, 2000), volcano monitoring is critical for public safety and hazard mitigation. Only with adequate monitoring systems in place can volcano observatories provide accurate and timely forecasts and alerts of possible eruptive activity. At most U.S. volcanoes, observatories traditionally have employed a two-component approach to volcano monitoring: (1) install instrumentation sufficient to detect unrest at volcanic systems likely to erupt in the not-too-distant future; and (2) once unrest is detected, install any instrumentation needed for eruption prediction and monitoring. This reactive approach is problematic, however, for two reasons. 1. At many volcanoes, rapid installation of new ground-1. based instruments is difficult or impossible. Factors that complicate rapid response include (a) eruptions that are preceded by short (hours to days) precursory sequences of geophysical and (or) geochemical activity, as occurred at Mount Redoubt (Alaska) in 1989 (24 hours), Anatahan (Mariana Islands) in 2003 (6 hours), and Mount St. Helens (Washington) in 1980 and 2004 (7 and 8 days, respectively); (b) inclement weather conditions, which may prohibit installation of new equipment for days, weeks, or even months, particularly at midlatitude or high-latitude volcanoes; (c) safety factors during unrest, which can limit where new instrumentation can safely be installed (particularly at near-vent sites that can be critical for precursor detection and eruption forecasting); and (d) the remoteness of many U.S. volcanoes (particularly those in the Aleutians and the Marianas Islands), where access is difficult or impossible most of the year. Given these difficulties, it is reasonable to anticipate that ground-based monitoring of eruptions at U.S. volcanoes will likely be performed primarily with instruments installed before unrest begins. 2. Given a growing awareness of previously undetected 2. phenomena that may occur before an eruption begins, at present the types and (or) density of instruments in use at most U.S. volcanoes is insufficient to provide reliable early warning of volcanic eruptions. As shown by the gap analysis of Ewert and others (2005), a number of U.S. volcanoes lack even rudimentary monitoring. At those volcanic systems with monitoring instrumentation in place, only a few types of phenomena can be tracked in near-real time, principally changes in seismicity, deformation, and large-scale changes in thermal flux (through satellite-based remote sensing). Furthermore, researchers employing technologically advanced instrumentation at volcanoes around the world starting in the 1990s have shown that subtle and previously undetectable phenomena can precede or accompany eruptions. Detection of such phenomena would greatly improve the ability of U.S. volcano observatories to provide accurate early warnings of impending eruptions, and is a critical capability particularly at the very high-threat volcanoes identified by Ewert and others (2005). For these two reasons, change from a reactive to a proactive volcano-monitoring strategy is clearly needed at U.S. volcanoes. Monitoring capabilities need to be expanded at virtually every volcanic center, regardless of its current state of

  3. Evidence for enhanced bioavailability of trace elements in the marine ecosystem of Deception Island, a volcano in Antarctica.

    PubMed

    Deheyn, Dimitri D; Gendreau, Philippe; Baldwin, Roberta J; Latz, Michael I

    2005-07-01

    This study assessed whether trace elements present at Deception Island, an active submarine volcano in the Antarctic Peninsula, show enhanced biological availability to the local marine community. Using a weak acid extraction method to dissolve organic material and leach associated but not constitutive trace elements of sediments, fifteen elements were measured from seafloor sediment, seawater particulates, and tissues of benthic (bivalves, brittlestars, sea urchins) and pelagic (demersal and pelagic fishes, krill) organisms collected in the flooded caldera. The highest element concentrations were associated with seafloor sediment, the lowest with seawater particulates and organism tissues. In the case of Ag and Se, concentrations were highest in organism tissue, indicating contamination through the food chain and biomagnification of those elements. The elements Al, Fe, Mn, Sr, Ti, and to a lesser extent Zn, were the most concentrated of the trace elements for all sample types. This indicates that the whole ecosystem of Deception Island is contaminated with trace elements from local geothermal activity, which is also reflected in the pattern of element contamination in organisms. Accordingly, element concentrations were higher in organisms collected at Deception Island compared to those from the neighboring non-active volcanic King George Island, suggesting that volcanic activity enhances bioavailability of trace elements to marine organisms. Trace element concentrations were highest in digestive tissue of organisms, suggesting that elements at Deception Island are incorporated into the marine food web mainly through a dietary route. PMID:15649525

  4. Ground deformation associated with the March 1996 earthquake swarm at Akutan volcano, Alaska, revealed by satellite radar interferometry

    USGS Publications Warehouse

    Lu, Z.; Wicks, C., Jr.; Power, J.A.; Dzurisin, D.

    2000-01-01

    In March 1996 an intense swarm of volcano-tectonic earthquakes (???3000 felt by local residents, Mmax = 5.1, cumulative moment of 2.7 ??1018 N m) beneath Akutan Island in the Aleutian volcanic arc, Alaska, produced extensive ground cracks but no eruption of Akutan volcano. Synthetic aperture radar interferograms that span the time of the swarm reveal complex island-wide deformation: the western part of the island including Akutan volcano moved upward, while the eastern part moved downward. The axis of the deformation approximately aligns with new ground cracks on the western part of the island and with Holocene normal faults that were reactivated during the swarm on the eastern part of the island. The axis is also roughly parallel to the direction of greatest compressional stress in the region. No ground movements greater than 2.83 cm were observed outside the volcano's summit caldera for periods of 4 years before or 2 years after the swarm. We modeled the deformation primarily as the emplacement of a shallow, east-west trending, north dipping dike plus inflation of a deep, Mogi-type magma body beneath the volcano. The pattern of subsidence on the eastern part of the island is poorly constrained. It might have been produced by extensional tectonic strain that both reactivated preexisting faults on the eastern part of the island and facilitated magma movement beneath the western part. Alternatively, magma intrusion beneath the volcano might have been the cause of extension and subsidence in the eastern part of the island. We attribute localized subsidence in an area of active fumaroles within the Akutan caldera, by as much as 10 cm during 1992-1993 and 1996-1998, to fluid withdrawal or depressurization of the shallow hydrothermal system. Copyright 2000 by the American Geophysical Union.

  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. PMID:22768379

  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. 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.

  8. Argon geochronology of late Pleistocene to Holocene Westdahl volcano, Unimak Island, Alaska

    USGS Publications Warehouse

    Calvert, Andrew T.; Moore, Richard B.; McGimsey, Robert G.

    2005-01-01

    High-precision 40Ar/39Ar geochronology of selected lavas from Westdahl Volcano places time constraints on several key prehistoric eruptive phases of this large active volcano. A dike cutting old pyroclastic-flow and associated lahar deposits from a precursor volcano yields an age of 1,654+/-11 k.y., dating this precursor volcano as older than early Pleistocene. A total of 11 geographically distributed lavas with ages ranging from 47+/-14 to 127+/-2 k.y. date construction of the Westdahl volcanic center. Lava flows cut by an apparent caldera-rim structure yielded ages of 81+/-5 and 121+/-8 k.y., placing a maximum date of 81 ka on caldera formation. Late Pleistocene and Holocene lavas fill the caldera, but most of them are obscured by the large summit icecap.

  9. Magnetic structure of Loihi Seamount, an active hotspot volcano in the Hawaiian Island chain

    E-print Network

    Lamarche, Amy J.

    2004-09-30

    them difficult to investigate. Because undersea volcanoes are made up of highly magnetic basaltic rock, it is possible to use variations in the magnetic field to explore the internal structure of such edifices. This study combines magnetic survey data...

  10. Shallow submarine volcano group in the early stage of island arc development: Geology and petrology of small islands south off Hahajima main island, the Ogasawara Islands

    NASA Astrophysics Data System (ADS)

    Kanayama, Kyoko; Umino, Susumu; Ishizuka, Osamu

    2014-05-01

    Small Islands south off Hahajima, the southernmost of the Ogasawara Archipelago, consist of primitive basalts (<12 wt.% MgO) to dacite erupted during the transitional stage immediately following boninite volcanism on the incipient arc to sustained typical oceanic arc. Strombolian to Hawaiian fissure eruptions occurring on independent volcanic centers for the individual islands under a shallow sea produced magnesian basalt to dacite fall-out tephras, hyaloclastite and a small volume of pillow lava, which were intruded by NE-trending dikes. These volcanic strata are correlated to the upper part (<40 Ma) of the Hahajima main island. Volcanic rock samples have slightly lower FeO*/MgO ratios than the present volcanic front lavas, and are divided into three types with high, medium and low La/Yb ratios. Basalt to dacite of high- and medium-La/Yb types show both tholeiitic (TH) and calc-alkaline (CA) differentiation trends. Low-La/Yb type belongs only to TH basalt. The multiple magma types are coexistence on the each island. TH basalts have phenocrysts of olivine, clinopyroxene and plagioclase, while CA basalts are free from plagioclase phenocrysts.

  11. Uplift, Subsidence, and Trapdoor Faulting at Sierra Negra Volcano, Galapagos Islands, from InSAR Observations and Mechanical Modeling

    NASA Astrophysics Data System (ADS)

    Yun, S.; Zebker, H.; Segall, P.

    2004-12-01

    In the last 10 years, Sierra Negra volcano, on the island of Isabella in the Galapagos, has experienced rapid uplift, trapdoor faulting (Amelung and Jonsson et al., Nature 2000), renewed inflation, and subsidence (Geist et al., JVGR in press). Boundary element calculations based on the InSAR observations constrain the magma chamber geometry at Sierra Negra. The surface deformation during the periods of inflation was caused by pressurization of a sill-like intrusion increasing in thickness by a maximum of 0.5 meter (Yun et al., JVGR in press). However, for such a shallow intrusion only the top of the magma chamber can be resolved using surface deformation observations; the data are insensitive to the sides and bottom of the chamber. A simple thermal analysis shows that intrusion must be at least 40 meters thick to remain liquid during the period of observations, so that the magma chamber at Sierra Negra is likely a thick sill or a flat-topped diapir. We model the stress field in the volcano assuming magma chamber geometries and pressure changes found from analysis of the InSAR data. By simulating both the inflation and faulting events, we hope to gain insights into the stress state within the volcano, and the conditions that favor faulting on the intra caldera fault system versus dike propagation and eruption. The stress acting on the pre-existing intra-caldera fault is a combination of pre-inflation, gravitational, and magmatic contributions. We bound the change in excess magma pressure using InSAR observations prior to the trapdoor-faulting event, resulting in a lower bound on the shear stress that triggered the faulting. Our results will have important implications for the stress state within the volcano, the mechanics of induced faulting and dike propagation, and may lead to better forecasts of future behavior.

  12. A White Killer Whale in the Central Aleutians

    Microsoft Academic Search

    MARTIN RENNER; KEVIN BELL

    We observed a white adult male killer whale (Orcinus orca) on 7 August 2000 off the north side of Adak Island, Aleutians. An open saddle and a rounded dorsal fin tip suggest that this whale belongs to the fish-eating (\\

  13. Relationship between regional changes of soil physical properties and volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali, Indonesia

    Microsoft Academic Search

    T. Tanaka; N. Sunarta

    1994-01-01

    The present paper shows the relationship between the regional changes of soil physical properties and the volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali, Indonesia, from the hydrogeological point of view based on the data obtained from field observations and laboratory experiments. The Bali soils data showed marked differences in regional distribution and their

  14. Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods

    NASA Astrophysics Data System (ADS)

    Kelly, C. L.; Lawrence, J. F.; Ebinger, C. J.

    2013-12-01

    Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods Cyndi Kelly1, Jesse F. Lawrence1, Cindy Ebinger2 1Stanford University, Department of Geophysics, 397 Panama Mall, Stanford, CA 94305, USA 2University of Rochester, Department of Earth and Environmental Science, 227 Hutchison Hall, Rochester, NY 14627, USA Low-magnitude seismic signals generated by processes that characterize volcanic and hydrothermal systems and their plumbing networks are difficult to observe remotely. Seismic records from these systems tend to be extremely 'noisy', making it difficult to resolve 3D subsurface structures using traditional seismic methods. Easily identifiable high-amplitude bursts within the noise that might be suitable for use with traditional seismic methods (i.e. eruptions) tend to occur relatively infrequently compared to the length of an entire eruptive cycle. Furthermore, while these impulsive events might help constrain the dynamics of a particular eruption, they shed little insight into the mechanisms that occur throughout an entire eruption sequence. It has been shown, however, that the much more abundant low-amplitude seismic 'noise' in these records (i.e. volcanic or geyser 'tremor') actually represents a series of overlapping low-magnitude displacements that can be directly linked to magma, fluid, and volatile movement at depth. This 'noisy' data therefore likely contains valuable information about the processes occurring in the volcanic or hydrothermal system before, during and after eruption events. In this study, we present a new method to comprehensively study how the seismic source distribution of all events - including micro-events - evolves during different phases of the eruption sequence of Sierra Negra Volcano in the Galapagos Islands. We apply a back-projection search algorithm to image sources of seismic 'noise' at Sierra Negra Volcano during a proposed intrusion event. By analyzing coherent seismic energy from all possible events to all available receivers, we generate a movie showing how seismic sources change spatially and temporally during the analysis period. This approach utilizes data from the entire seismic record and could ultimately provide a more complete understanding of how seismic sources change throughout the eruptive sequence rather than during a particular eruption event. This information could help to 1) answer fundamental questions about volcano-tectonic processes and 2) make more accurate assessments of volcanic hazards. Preliminary results from application of the methodology to seismic data collected by a dense array of 3-component geophones at El Tatio Geyser Field in northern Chile during October 2012 will also be introduced.

  15. The last 5000 years of activity at Sete Cidades volcano (São Miguel Island, Azores): Implications for hazard assessment

    NASA Astrophysics Data System (ADS)

    Queiroz, G.; Pacheco, J. M.; Gaspar, J. L.; Aspinall, W. P.; Guest, J. E.; Ferreira, T.

    2008-12-01

    Sete Cidades is a central volcano with a summit caldera at the western end of São Miguel Island, Azores. Its stratigraphy comprises two main geological groups: the Inferior Group, the units of which date from more than 200 000 years ago through to 36 000 years before present, consisting of thick lava flows and subaerial volcaniclastic deposits that built the base of the central volcano; and the Superior Group which comprises all the activity from the last 36 000 years, including pumice and scoria fallout and PDC deposits with minor lava flows. The volcanostratigraphy is divided into six main formations — Risco, Ajuda, Bretanha, Lombas, Santa Bárbara and Lagoas, each defined by different activity phases in the volcano's evolution. The present caldera developed in three phases associated with massive paroxysmal eruptions which occurred approximately 36 000, 29 000 and 16 000 years before present. Since the last caldera forming event, eruptive activity has been predominantly explosive and a variety of deposits have been produced by different eruptive styles, associated with three specific settings: (1) pumice fall deposits, pyroclastic density currents and hydromagmatic events from eruptions inside the caldera; (2) lava domes, cinder cones and basaltic lava flows from eruptions on the volcano flanks; (3) tuff ring and tuff deposits from surtseyan eruptions offshore. The more recent history of the volcano is marked by a change in the intracaldera activity from dominantly magmatic behaviour to a hydromagmatic character, which happened about 5000 years ago. Since then, at least 15 basaltic subaerial and submarine eruptions have occurred on the volcano flanks and 17 trachytic (s.l.) explosive eruptions have occurred within the caldera, the most recent of which took place about 700 years ago. This eruptive frequency makes Sete Cidades probably the most active volcanic centre in the Azores. In this paper we present the stratigraphy and a description of the deposits which originate from the last 5000 years, in order to delineate Sete Cidades' recent eruptive history for the purpose of estimating the hazard associated with this volcano. An event tree has been designed to systematize possible future eruptive scenarios and to aid the assessment of relative probabilities of occurrence of different potential eruptive styles. The probabilities for all nodes on the event tree, together with their associated uncertainties, were obtained by expert elicitation, providing results that accord with the geologic record. These probability estimates indicate that (1) basaltic strombolian and submarine eruptions are the most likely to occur, (2) trachytic activity from the central volcano magmatic system is more probable in the intracaldera environment than on the flanks, and (3) explosive activity is more likely than effusive for the trachytic system. Worst-case scenario and maximum expected events are identified according to the eruptive scenarios and their probabilities of occurrence.

  16. 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 submarine prosecution of the SdF system were already studied and unveiled, the complete description of the in-depth extension of the system and the overall volume estimation is still poorly known. This has important implications for the hazard assessment of the landslide structure and most generally of the entire volcanic edifice. The application of a classical geomagnetic prospection to describe a landslide feature is an uncommon procedure yet it can be considered as innovative approach, having the advantages of effectiveness, low cost and expedition typical of the geomagnetic survey. Here we present the interpretation of the newly acquired high-resolution magnetic dataset, thanks to susceptibility and magnetic remanence values gathered from on-land rock samples at Stromboli. A 3D inverse model is here proposed, allowing a full definition of the submerged SdF structure geometry.

  17. Alaska Volcano Observatory at 20

    NASA Astrophysics Data System (ADS)

    Eichelberger, J. C.

    2008-12-01

    The Alaska Volcano Observatory (AVO) was established in 1988 in the wake of the 1986 Augustine eruption through a congressional earmark. Even within the volcanological community, there was skepticism about AVO. Populations directly at risk in Alaska were small compared to Cascadia, and the logistical costs of installing and maintaining monitoring equipment were much higher. Questions were raised concerning the technical feasibility of keeping seismic stations operating through the long, dark, stormy Alaska winters. Some argued that AVO should simply cover Augustine with instruments and wait for the next eruption there, expected in the mid 90s (but delayed until 2006), rather than stretching to instrument as many volcanoes as possible. No sooner was AVO in place than Redoubt erupted and a fully loaded passenger 747 strayed into the eruption cloud between Anchorage and Fairbanks, causing a powerless glide to within a minute of impact before the pilot could restart two engines and limp into Anchorage. This event forcefully made the case that volcano hazard mitigation is not just about people and infrastructure on the ground, and is particularly important in the heavily traveled North Pacific where options for flight diversion are few. In 1996, new funding became available through an FAA earmark to aggressively extend volcano monitoring far into the Aleutian Islands with both ground-based networks and round-the-clock satellite monitoring. Beyond the Aleutians, AVO developed a monitoring partnership with Russians volcanologists at the Institute of Volcanology and Seismology in Petropavlovsk-Kamchatsky. The need to work together internationally on subduction phenomena that span borders led to formation of the Japan-Kamchatka-Alaska Subduction Processes (JKASP) consortium. JKASP meets approximately biennially in Sapporo, Petropavlovsk, and Fairbanks. In turn, these meetings and support from NSF and the Russian Academy of Sciences led to new international education and research opportunities for Russian and American students. AVO was a three-way partnership of the federal and state geological surveys and the state university from the start. This was not a flowering of ecumenism but was rather at the insistence of the Alaska congressional delegation. Such shared enterprises are not managerially convenient, but they do bring a diversity of roles, thinking, and expertise that would not otherwise be possible. Through AVO, the USGS performs its federally mandated role in natural hazard mitigation and draws on expertise available from its network of volcano observatories. The Alaska Division of Geological and Geophysical Surveys performs a similar role at the state level and, in the tradition of state surveys, provides important public communications, state data base, and mapping functions. The University of Alaska Fairbanks brought seismological, remote sensing, geodetic, petrological, and physical volcanological expertise, and uniquely within US academia was able to engage students directly in volcano observatory activities. Although this "model" cannot be adopted in total elsewhere, it has served to point the USGS Volcano Hazards Program in a direction of greater openness and inclusiveness.

  18. 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 ?m size range. High resolution grain size analyses show that >78% of sediment in the hydrothermal mound samples are between 63-2 ?m with 6-20% clay sized (<2 ?m) whereas <40% of the primary volcaniclastic sediment is between 63-2 ?m with ~2% clay sized. The presence of clay minerals (smectite, illite, talc, and I/S mixed layer) in the hydrothermal mound samples was confirmed x-ray diffraction analysis. Differences in major oxide composition of the two sediment types (depletion in Al2O3 but enrichments in MgO and Fe2O3* in the mound sample relative to primary volcaniclastic sediment) suggest that mound sediment has experienced hydrothermal alteration/mineralization. Elevated concentrations of As, Sb and Cu in the mound sediment also indicate a strong hydrothermal contribution. The bulk composition of the mound sediment can be reasonably modeled as a mixture of ~78% primary volcaniclastic sediment, ~30% alteration clay minerals, and ~2% pyrite. The percentage of clay required in the model is ~10% greater than the fraction (~20%) observed in the hydrothermal mound sample but some of the alteration products may consist of larger grains that have not been analyzed individually.

  19. The 2003 eruption of Anatahan volcano, Commonwealth of the Northern Mariana Islands: Chronology, volcanology, and deformation

    USGS Publications Warehouse

    Trusdell, F.A.; Moore, R.B.; Sako, M.; White, R.A.; Koyanagi, S.K.; Chong, R.; Camacho, J.T.

    2005-01-01

    The first historical eruption on Anatahan Island occurred on 10 May 2003 from the east crater of the volcano. The eruption was preceded by several hours of seismicity. Two and a half hours before the outbreak, the number of earthquakes surged to more than 100 events per hour. At 0730 UTC, the Washington Volcanic Ash Advisory Center issued an ash advisory. Although the eruption lasted for 3 months, the majority of erupted material was expelled during the first 2 weeks. The opening episode of the eruption resulted in a deposit of juvenile scoria and lithic clasts, the latter derived from geothermally altered colluvial fill from the vent area. The opening episode was followed by crater enlargement and deepening, which produced deposits of coarse, reddish-brown ash containing a mixture of juvenile and lithic clasts. The third episode of the eruption produced coarse ash and lapilli comprised of juvenile scoria and minor amounts of lithics. Plume heights were 4500 to 13,000 m for the initial three phases. The fourth episode, from about May 18 through early August, was characterized by smaller plume heights of 900 to 2400 m, and steam was the dominant component. Minor amounts of coarse ash and accretionary-lapilli ash comprise most of the deposits of the fourth episode, although ballistic blocks and bombs of andesite lava are also locally present. These andesite blocks were emplaced by an explosion on 14 June, which destroyed a small lava dome extruded during the first week of June. Activity waned as the summer progressed, and subsequent ash deposits accumulated in July and early August, by which time the eruption had effectively ended. In September and October, degassing and geothermal activity continued, characterized by small geysers, boiling water, and jetting steam. Noteworthy deviations from this activity were a surge event in late May-early June and the destruction of the lava dome on 14 June. We calculated on-land tephra-fall deposits to have a bulk volume of about 27.5 ?? 106 m3, covering an area of 40.6 km2. We determined the juvenile to lithic content of the deposits and corrected the bulk volume to a juvenile volume of 24.0 ?? 106 m3. We use a volume corrected density of 1.32 g/cm3 to convert the juvenile volume of 24.0 ?? 106 m3 to a magma volume of 13.2 ?? 106 m3. Using the methods of Fierstein and Nathenson (1992) [Fierstein, J., Nathenson, M., 1992. Another look at the calculation of fallout tephra volumes. Bull. Volcanology. 54, 156-167.], we computed the total eruption volume at 45.4 ?? 106 m3. Deformation surveys recorded large changes surrounding the east crater. The modeled volumetric change based on the surveys was 0.82 ?? 106 m3 of magma, which we estimate corresponds to a minimum intrusion of 10 ?? 106 m3 of magma which is in good agreement with our calculated on-land magma volume.

  20. 78 FR 64891 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-30

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Central Aleutian district (CAI...total allowable catch (TAC) of Atka mackerel in this area allocated to vessels...

  1. 75 FR 6129 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-08

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Eastern Aleutian District and...the 2010 A season allocation of Atka mackerel in these areas allocated to vessels...

  2. 78 FR 42023 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-15

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...is opening directed fishing for Atka mackerel in the Central Aleutian district (CAI...total allowable catch (TAC) of Atka mackerel in the CAI by vessels participating...

  3. 75 FR 14498 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-26

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Central Aleutian District of the...the 2010 A season allocation of Atka mackerel in this area allocated to vessels...

  4. 78 FR 25878 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-03

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Central Aleutian district (CAI...the A season allowance of the 2013 Atka mackerel total allowable catch (TAC) in...

  5. 75 FR 64957 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-21

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...is opening directed fishing for Atka mackerel in the Eastern Aleutian District and...total allowable catch (TAC) of Atka mackerel in these areas specified for...

  6. 77 FR 26212 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-03

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Central Aleutian district (CAI...the A season allowance of the 2012 Atka mackerel total allowable catch (TAC) in...

  7. 77 FR 39441 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Central Aleutian district (CAI...total allowable catch (TAC) of Atka mackerel in this area allocated to vessels...

  8. 75 FR 4491 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-28

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...is opening directed fishing for Atka mackerel in the Eastern Aleutian District and...total allowable catch (TAC) of Atka mackerel in these areas specified for...

  9. 78 FR 35771 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...prohibiting directed fishing for Atka mackerel in the Central Aleutian district (CAI...total allowable catch (TAC) of Atka mackerel in this area allocated to vessels...

  10. 76 FR 65975 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-25

    ...subarea and Eastern Aleutian district (BS/EAI) of the Bering Sea and Aleutian Island...The 2011 TAC of Atka mackerel, in the BS/EAI, allocated to vessels participating...directed fishing for Atka mackerel in the BS/EAI by vessels participating in the...

  11. 78 FR 64892 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-30

    ...subarea and Eastern Aleutian district (BS/EAI) of the Bering Sea and Aleutian Islands...The 2013 TAC of Atka mackerel, in the BS/EAI, allocated to vessels participating...directed fishing for Atka mackerel in the BS/EAI by vessels participating in the...

  12. 76 FR 10780 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-28

    ...subarea and Eastern Aleutian district (BS/EAI) of the Bering Sea and Aleutian Island...allowance of the 2011 Atka mackerel TAC, in the BS/ EAI, allocated to vessels participating...BSAI trawl limited access fishery in the BS/EAI. After the effective dates of...

  13. 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.

  14. Lead isotopes behavior in the fumarolic environment of the Piton de la Fournaise volcano (Reunion Island)

    E-print Network

    Lead isotopes behavior in the fumarolic environment of the Piton de la Fournaise volcano (Re the issue of Pb isotope behav- ior in volcanic fumaroles, as the composition of the degassing source), Ca­Mg­Al­Fe fluoride (e.g., ralstonite) and native sulfur. The high-tempera- ture deposits show trace

  15. ACTIVE VOLCANOES OF THE KURILE ISLANDS --A Quick Reference Stratovolcano with summit crater

    E-print Network

    the early 20 century, it is likely thatmanyeruptionswentundocumented. The Sakhalin Volcanic Eruption provided by colleagues at the Sakhalin Department of the Geophysical Surveyofthe Sakhalin Is. Km ak achta KEY Number on map - VOLCANO (1 - 6 ­ monitored by KVERT, 7 - 36 ­ monitored

  16. Three-dimensional shear velocity anisotropic model of Piton de la Fournaise Volcano (La Réunion Island) from ambient seismic noise

    NASA Astrophysics Data System (ADS)

    Mordret, Aurélien; Rivet, Diane; Landès, Matthieu; Shapiro, Nikolaï M.

    2015-01-01

    We cross correlate 4 years of seismic noise from the seismic network of Piton de la Fournaise Volcano (La Réunion Island) to measure the group velocity dispersion curves of Rayleigh and Love waves. We average measurements from vertical and radial components to obtain 577 Rayleigh wave dispersion curves. The transverse components provided 395 Love wave dispersion curves. We regionalize the group velocities measurements into 2-D velocity maps between 0.4 and 8 s. Finally, we locally inverted these maps for a pseudo 3-D anisotropic shear-velocity model down to 3 km below the sea level using a Neighborhood Algorithm. The 3-D isotropic shear-wave model shows three distinct high-velocity anomalies surrounded by a low-velocity ring. The anomaly located below the present "Plaine des Sables" could be related to an old intrusive body at the location of the former volcanic center before it migrated toward its present location. The second high-velocity body located below the summit of the volcano likely corresponds to the actual preferential dyke intrusion zone as highlighted by the seismicity. The third high-velocity anomaly located below the "Grandes Pentes" and the "Grand Brûlé" areas and is an imprint of the solidified magma chamber of the dismantled "Les Alizés" Volcano. Radial anisotropy shows two main anomalies: positive anisotropy above sea level highlighting the recent edifice of Piton de la Fournaise with an accumulation of horizontal lava flows and the second one below the sea level with a negative anisotropy corresponding to the ancient edifice of Piton de la Fournaise dominated by intrusions of vertical dykes.

  17. Aleutian goose's rebound a problem

    E-print Network

    Johnson, Matthew

    Aleutians, one of the smaller members of the Canada goose complex, which contains two species and at leastAleutian goose's rebound a problem for agriculture Glen Martin, Chronicle Environment Writer Sunday, supine in camouflaged blinds near a pond surrounded with goose decoys, hoped to kill a few. A flock

  18. GPS Application to the Study of Ground Deformation in the Volcano Tectonic System of the Graciosa Island (Azores)

    NASA Astrophysics Data System (ADS)

    Rodrigues, R.; Ferreira, T.; Gaspar, J. L.

    2009-04-01

    The Azores archipelago is located in North Atlantic Ocean, in the junction of Eurasian, American and African plates, which reflect the existence of a complex system of fractures, namely the Mid-Atlantic Ridge, the Eastern Azorean fracture zone, the Terceira Rift and the Gloria Fault. The Azores are, therefore, an excellent place for the application and development of various volcano tectonic observation techniques (geophysics, geochemistry and geodesy) and preliminary modeling of some of the volcanic systems. In the scope of the Azores seismovolcanic monitoring programme a geodetic network was implemented in Graciosa Island. This network is composed by thirty-four geodetic benchmarks distributed according to the main volcanic and tectonic structures. A continuous GPS station installed in the island since 2003 is used as reference. In the last five years there have been eight observation campaigns, which took place between September 2003 and July 2008. For the processing of the GPS observations it was used the Bernese GPS Software 5 (developed at the University of Berne). For the GPS processing of September 2003, March 2004 and August 2004 campaigns, three processing strategies were tested to study the effect of the correction of troposphere refraction, resulting in three different solutions: one solution with pure modeling (no estimation of troposphere parameters) and two solutions with estimation of one and two troposphere parameters, using Niell's hydrostatic mapping function. A processing methodology was created, a good and reliable zero-epoch for the study of the volcanic-tectonic system of the Graciosa Island was established and a preliminary evaluation of the velocity field was obtained for Graciosa island.

  19. Combining CSD and isotopic microanalysis: Magma supply and mixing processes at Stromboli Volcano, Aeolian Islands, Italy

    NASA Astrophysics Data System (ADS)

    Morgan, D. J.; Jerram, D. A.; Chertkoff, D. G.; Davidson, J. P.; Pearson, D. G.; Kronz, A.; Nowell, G. M.

    2007-08-01

    Integrating isotopic microanalysis with other analytical techniques creates powerful new methodologies for understanding the evolution of rock samples at the sub-grain scale. Here we present Crystal Size Distribution (CSD) data for a 26,000 year old sample from Stromboli Volcano and accompanying isotopic microanalysis of the phenocrysts. A technique, called the ICSD plot, is introduced which given stated assumptions allows the integration of both sets of data to generate timelines of isotopic evolution through the volcanic system. The combined approach is powerful, allowing investigation of the magma supply, mixing, crystallisation and contamination processes prior to eruption of a volcanic sample. For Stromboli Volcano, the combined analysis suggests that the change in magma type following a cone collapse took roughly five years to complete, similar to the timescale of changes seen in recent decades.

  20. O-saturated island arc low-K tholeiite magmas: a case study of the Izu-Oshima volcano in the Izu arc

    NASA Astrophysics Data System (ADS)

    Hamada, Morihisa; Okayama, Yuko; Kaneko, Takayuki; Yasuda, Atsushi; Fujii, Toshitsugu

    2014-12-01

    Island arc low-K tholeiites are basaltic magmas erupting from frontal arc volcanoes of juvenile arcs associated with the subduction of old and cold plates. We investigated the origins of geochemical variation in volcanic rocks having multiple phase saturated liquid compositions from the Izu-Oshima volcano in the northern Izu arc. The geochemical variations in the liquids fall between two endmember trends, namely higher- and lower-Al/Si trends. Polybaric differentiation of H2O-saturated melts between a 4-km-deep magma chamber and degassed melts near the surface should be responsible for the observed variation in the liquids.

  1. Identifying potential habitat for the endangered Aleutian shield fern using topographical characteristics

    USGS Publications Warehouse

    Duarte, Adam; Wolcott, Daniel M.; Chow, T. Edwin, Ricca, Mark A.

    2012-01-01

    The Aleutian shield fern Polystichum aleuticum is endemic to the Aleutian archipelago of Alaska and is listed as endangered pursuant to the U.S. Endangered Species Act. Despite numerous efforts to discover new populations of this species, only four known populations are documented to date, and information is needed to prioritize locations for future surveys. Therefore, we incorporated topographical habitat characteristics (elevation, slope, aspect, distance from coastline, and anthropogenic footprint) found at known Aleutian shield fern locations into a Geographical Information System (GIS) model to create a habitat suitability map for the entirety of the Andreaonof Islands. A total of 18 islands contained 489.26 km2 of highly suitable and moderately suitable habitat when weighting each factor equally. This study reports a habitat suitability map for the endangered Aleutian shield fern using topographical characteristics, which can be used to assist current and future recovery efforts for the species.

  2. Co-existence of two distinct magma sources in an island arc volcano: evidence from Montserrat, Lesser Antilles Arc

    NASA Astrophysics Data System (ADS)

    Cassidy, M.; Taylor, R. N.; Palmer, M. R.; Trofimovs, J.

    2011-12-01

    The South Soufrière Hills (SSH), located on the southern tip of the volcanically active island of Montserrat, West Indies, hosts the most complex and interesting volcanic deposits on the island in terms of their geochemistry and volcanic history. In this study we examine the composition of submarine SSH deposits in marine sediment cores and volcanics sampled during subaerial mapping of the SSH and other volcanic centres on Montserrat. SSH volcanism is found to represent an important compositional change in the magmatic evolution of Montserrat with implications for the origin of components in the Caribbean subduction system. Marine sediment cores and subaerial field mapping of the SSH volcanic centre document voluminous multi-stage flank failures of the SSH, which successively cut into older and chemically distinct stratigraphy as the collapses progressed. Nd, Sr and high-precision double-spike Pb isotopes combined with trace element analyses and SEM imagery of the SSH deposits indicate that this volcano experienced multiple injections of mafic magma followed by magmatic differentiation and episodic explosive eruptions of andesitic pumice, which were triggered by fresh mafic pulses. We demonstrate that the SSH is chemically distinct from the rest of the volcanic centres on the island, suggesting that magmas from the Soufrière Hills and SSH come from entirely separate sources. 206Pb/204Pb plotted against ?7/4Pb and ?8/4Pb show that Montserrat falls along two differing trends; one defined by the SSH volcanic centre and the second comprising the three other volcanic centres (Silver Hills, Centre Hills and Soufrière Hills). Magma generation at these centres (excluding the SSH) reflects an input of pelagic sediment, likely in the form of partial melt as indicated by elevated Th/Nd and lower 143/144Nd. However, the SSH has more of slab-fluid rich signature relative to sediment as suggested by lower Ce/Pb, 206Pb/204Pb and ?7/4Pb combined with higher 87Sr/86Sr. The low, but stable Nb/Zr values relative to MORB, suggests that the mantle source for each volcanic centre has remained constant despite the deviation in sediment flux reflected during SSH activity. By extension from the high-precision Pb isotope results, we can suggest that subduction fluid, and sediment melt components can be discriminated within a single arc volcano.

  3. Enhancement of sub-daily positioning solutions for surface deformation surveillance at El Hierro volcano (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Prates, G.; García, A.; Fernández-Ros, A.; Marrero, J. M.; Ortiz, R.; Berrocoso, M.

    2013-06-01

    El Hierro Island in the Canary Archipelago recently experienced a submerged eruption a few kilometers off its southern shore, detected 2011 October 10 on the island's south-rift alignment. The seismic activity suddenly increased around mid 2011 July, and ground deformation was then detected on the only geodetic benchmark that is continuously observed by global navigation satellite systems techniques and provides public data access. Based on that information, several other global navigation satellite system signal receivers were deployed on the island to provide continuous observation. For data collected by these receivers, a processing strategy was applied to achieve millimeter-level half-hourly positioning solutions. Position updates every 24 h are satisfactory to determine tectonic-plates' velocities. Updates near 1 s or less are required to characterize seismic waves. In between, minute-level updates are well suited for monitoring active volcano's inflation or deflation, providing an optimal time resolution of the local ground deformation. In half-hourly positioning solutions, the heterogeneous satellites' distribution in their orbital planes gives different constraints during satellite-constellation revolution, which can bias the solutions. Also, several geophysical influences can bias the solutions, including those related to gravitational movements. These influences have mostly semi-diurnal periodicities and may be considered Gaussian colored noise on the position's time series. Daily solutions that average out these influences can be applied in active volcanoes, but they can impose some limitations because they average the daily deformation, and the update waiting time is not suitable when near real-time surveillance is mandatory. These semi-diurnal biases do need to be removed or minimized to achieve millimeter-level sub-daily positioning solutions, however, and to do so, a discrete Kalman filter was applied to enhance the half-hourly positioning solutions required during El Hierro's 2011-2012 unrest and eruption. Throughout El Hierro's volcanic activity, there were correlations between ground deformation and seismic activity. Many times the deformation preceded the earthquakes, though at other times the seismic activity was followed by the ground deformation response. This correlation is the outcome of ground deformation taking place as the result of energy accommodation, whereas seismic events correspond to energy release. Hence, those observed correlations indicate that the Kalman filter-enhanced half-hourly positioning solutions measured local ground deformation accurately; they were not a mathematical "trick" producing a spurious precision.

  4. Tephra-Producing Eruptions of Holocene Age at Akutan Volcano, Alaska; Frequency, Magnitude, and Hazards

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Wallace, K. L.; Schwaiger, H.

    2012-12-01

    Akutan Volcano in the eastern Aleutian Islands of Alaska is one of the most historically active volcanoes in the Aleutian arc (43 eruptions in about the past 250 years). Explosive eruptions pose major hazards to aircraft flying north Pacific air routes and to local infrastructure on Akutan and neighboring Unalaska Island. Air travel, infrastructure, and population in the region have steadily increased during the past several decades, and thus it is important to better understand the frequency, magnitude, and characteristics of tephra-producing eruptions. The most recent eruption was a VEI 2 event on March 8-May 21, 1992 that resulted in minor ash emissions and trace amounts of proximal fallout. Nearly continuous low-level emission of ash and steam is typical of historical eruptions, and most of the historical events have been similar in magnitude to the 1992 event. The most recent major eruption occurred about 1600 yr. B.P. and likely produced the ca. 2-km diameter summit caldera and inundated valleys that head on the volcano with pyroclastic-flow and lahar deposits that are tens of meters thick. The 1600 yr. B.P. eruption covered most of Akutan Island with up to 2.5 m of coarse scoriaceous tephra fall, including deposits 0.5-1 m thick near the City of Akutan. Tephra-fall deposits associated with this eruption exhibit a continuous sequence of black, fine to coarse scoriaceous lapilli overlain by a lithic-rich facies and finally a muddy aggregate-rich facies indicating water involvement during the latter stages of the eruption. Other tephra deposits of Holocene age on Akutan Island include more than a dozen discrete fine to coarse ash beds and 3-6 beds of scoriaceous, coarse lapilli tephra indicating that there have been several additional major eruptions (>VEI 3) of Akutan Volcano during the Holocene. Radiocarbon dates on these events are pending. In addition to tephra falls from Akutan, other fine ash deposits are found on the island that originated from other Aleutian arc volcanoes. Tephra deposits from typical VEI 2 historical eruptions are not well preserved on the island so tephra-fall frequency estimated from stratigraphic studies is underestimated. Akutan Island is home to the largest seafood processing plant in North America and has a workforce of more than one thousand people. Other infrastructure consists of a recently constructed paved airfield on neighboring Akun Island (25 km east of the active vent) and a new boat harbor at the head of Akutan Harbor. Plans to develop greenhouses, tourism, and increased cold storage capacity on Akutan and Akun Islands also are evolving. To support the power demands of the development efforts, The City of Akutan is considering the utilization of geothermal resources on the island that are located in Hot Springs Bay valley northwest of the city. All of the existing and planned infrastructure, water supply, and residential areas are about 12 km downwind (east) of the volcano and are at risk from ash-producing eruptions. The historical eruptive history suggests that VEI 2 eruptions are plausible in the near future and the Holocene tephra-fall record indicates that large eruptions (VEI 4 or larger) occur about every few thousand years. Numerical modeling of tephra fallout based on the record of ash-producing eruptions will be used to improve tephra-fall hazard assessments for the area.

  5. Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island, Motmot, in its caldera lake. VII. Overview and

    Microsoft Academic Search

    I. W. B. Thornton; S. Cook; J. S. Edwards; R. D. Harrison; C. Schipper; M. Shanahan

    Location, aims Long Island's biota was destroyed by volcanic eruption in c. 1645, and Motmot, an emergent island in its caldera lake, was re-created in 1968, providing a nested pair of natural colonization sequences. In 1999 we surveyed the plants and vertebrates of Long and the entire biota of Motmot for comparison with previous surveys of Long (1932, 1972, birds

  6. Characterization of pyroclastic deposits and pre-eruptive soils following the 2008 eruption of Kasatochi Island Volcano, Alaska

    USGS Publications Warehouse

    Wang, B.; Michaelson, G.; Ping, C.-L.; Plumlee, G.; Hageman, P.

    2010-01-01

    The 78 August 2008 eruption of Kasatochi Island volcano blanketed the island in newly generated pyroclastic deposits and deposited ash into the ocean and onto nearby islands. Concentrations of water soluble Fe, Cu, and Zn determined from a 1:20 deionized water leachate of the ash were sufficient to provide short-term fertilization of the surface ocean. The 2008 pyroclastic deposits were thicker in concavities at bases of steeper slopes and thinner on steep slopes and ridge crests. By summer 2009, secondary erosion had exposed the pre-eruption soils along gulley walls and in gully bottoms on the southern and eastern slopes, respectively. Topographic and microtopographic position altered the depositional patterns of the pyroclastic flows and resulted in pre-eruption soils being buried by as little as 1 m of ash. The different erosion patterns gave rise to three surfaces on which future ecosystems will likely develop: largely pre-eruptive soils; fresh pyroclastic deposits influenced by shallowly buried, pre-eruptive soil; and thick (>1 m) pyroclastic deposits. As expected, the chemical composition differed between the pyroclastic deposits and the pre-eruptive soils. Pre-eruptive soils hold stocks of C and N important for establishing biota that are lacking in the fresh pyroclastic deposits. The pyroclastic deposits are a source for P and K but have negligible nutrient holding capacity, making these elements vulnerable to leaching loss. Consequently, the pre-eruption soils may also represent an important long-term P and K source. ?? 2010 Regents of the University of Colorado.

  7. Assessment of the exposure of islanders to ash from the Soufriere Hills volcano, Montserrat, British West Indies

    PubMed Central

    Searl, A; Nicholl, A; Baxter, P

    2002-01-01

    Background and Aims: The Soufriere Hills volcano, Montserrat, has been erupting since July 1995 and volcanic ash has fallen on the island throughout most of the eruption. The ash contains substantial quantities of respirable particles and unusually large amounts (15–20%) of the crystalline silica mineral, cristobalite. The purpose of the surveys described here, undertaken between December 1996 and April 2000, was to determine levels of personal exposure of islanders to volcanic ash and cristobalite in order to inform advice on the associated risks to health and the measures required to reduce exposure. Methods: Surveys of personal exposure to respirable dust and cristobalite were undertaken using cyclone samplers. In addition, direct reading instruments (DUSTTRAK) were used to monitor ambient air concentrations of PM10 at fixed sites and also to provide information about exposures to airborne particles associated with selected activities. Results: Environmental concentrations of airborne ash have been greatest in the areas where the most ash has been deposited and during dry weather. Individual exposure to airborne ash was related to occupation, with the highest exposures among gardeners, cleaners, roadworkers, and police at roadside checkpoints. During 1997 many of these individuals were exposed to concentrations of cristobalite that exceeded the ACGIH recommended occupational exposure limit. Since the population became confined to the north of the island in October 1997, even those in relatively dusty occupations have received exposures to cristobalite well below this limit. Conclusions: Most of the 4500 people who have remained on island since the eruption began have not been exposed to sufficiently high concentrations of airborne dust for long enough to be at risk of developing silicosis. However, more than a dozen individuals continued to experience frequent high occupational exposures to volcanic ash, some of whom may have had sufficient exposure to crystalline silica to be at risk of developing mild silicosis. If volcanic activity were to deposit further ash over the occupied areas of the island during the coming years, the risks of silicosis will become more substantial. PMID:12151608

  8. Mt. St. Augustine, Alaska: Geochemical evolution of an eastern Aleutian volcanic center

    SciTech Connect

    Johnson, K.E. (Univ. of Florida, Gainesville, FL (United States). Dept. of Geology); Harmon, R.S. (NERC Isotope Geosciences Lab., Keyworth (United Kingdom). Kingsley Dunham Centre); Moorbath, S. (Univ. of Oxford (United Kingdom). Dept. of Earth Sciences); Sigmarsson, O. (Univ. Blaise Pascal and CNRS, Clermont-Ferrand (France))

    1993-04-01

    Mt. St. Augustine is a calc-alkaline Quaternary volcano, situated within Cook Inlet, Alaska. The island is composed of low- to medium-K andesite and dacite domes and pyroclastic flows. Major element variations indicate the magmatic evolution is dominantly influenced by fractionation and magma-mixing processes. Incompatible element and isotopic compositions suggest that despite its continental location, crustal assimilation is not significant factor in magmatic evolution. Alkali contents for Augustine are generally lower than elsewhere in the Aleutians (e.g. Augustine Cs/Rb = 0.016--0.024, K/Rb = 372--553; Aleutians Cs/Rb = 0.016--0.17, K/Rb = 231--745). Sr- and Nd-isotope ratios encompass narrow ranges ([sup 87]Sr/[sup 86]Sr = 0.70317--0.70343; [sup 143]Nd/[sup 144]Nd = 0.513011--0.513085), characteristic of uncontaminated mantle-derived melts. U-Th disequilibrium isotopic values also indicate little or no assimilation of evolved continental crust. Pb-isotopic ranges are also relatively restricted ([sup 206]Pb/[sup 204]Pb = 18.62--18.82; [sup 207]Pb/[sup 204]Pb = 15.54--15.57; [sup 208]Pb/[sup 204]Pb = 38.18--38.34) and comparison with north Pacific enriched (OIB) and depleted (MORB) mantle sources suggest the incorporation of only a small percentage of subducted terrigenous sediments. A model for Augustine magma genesis is proposed where parental magmas are generated by 5--20% partial melting of a lherzolite mantle with up to a 5% subducted terrigenous sediment component. The major influence of the thickened continental crust is to prevent the ascent and eruption of basaltic magma. The data exhibit no temporal variations, indicating that the magmatic system which produced the historic eruptions is well established.

  9. 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

  10. Ground deformation of Tenerife volcano island revealed by 1992-2005 DInSAR time series:

    NASA Astrophysics Data System (ADS)

    Tizzani, P.

    2009-04-01

    We study the state of deformation of Tenerife Island using Differential Synthetic Aperture Radar Interferometry (DInSAR). We apply the Small BAseline Subset (SBAS) DInSAR algorithm to radar images acquired from 1992 to 2005 by ERS sensors to determine the deformation rate distribution and the time series for the coherent pixels identified in the island. Our analysis reveals that the summit area of the volcanic edifice is characterized by a continuous subsidence extending well beyond Las Cañadas caldera rim and corresponding to the intrusive core of the island. These results, coupled with GPS ones, structural and geological information and deformation modelling, suggest that the intrusive complex is subsiding into a weak lithosphere and that the volcanic edifice is in a state of compression. We also detect more localized deformation patterns correlated with water table changes and variations in the time deformation associated with the seismic crisis in 2004.

  11. Gaseous transport and deposition of gold in magmatic fluid: evidence from the active Kudryavy volcano, Kurile Islands

    NASA Astrophysics Data System (ADS)

    Yudovskaya, Marina A.; Distler, Vadim V.; Chaplygin, Ilya V.; Mokhov, Andrew V.; Trubkin, Nikolai V.; Gorbacheva, Sonya A.

    2006-03-01

    The distribution of gold in high-temperature fumarole gases of the Kudryavy volcano (Kurile Islands) was measured for gas, gas condensate, natural fumarolic sublimates, and precipitates in silica tubes from vents with outlet temperatures ranging from 380 to 870°C. Gold abundance in condensates ranges from 0.3 to 2.4 ppb, which is significantly lower than the abundances of transition metals. Gold contents in zoned precipitates from silica tubes increase gradually with a decrease in temperature to a maximum of 8 ppm in the oxychloride zone at a temperature of approximately 300°C. Total Au content in moderate-temperature sulfide and oxychloride zones is mainly a result of Au inclusions in the abundant Fe-Cu and Zn sulfide minerals as determined by instrumental neutron activation analysis. Most Au occurs as a Cu-Au-Ag triple alloy. Single grains of native gold and binary Au-Ag alloys were also identified among sublimates, but aggregates and crystals of Cu-Au-Ag alloy were found in all fumarolic fields, both in silica tube precipitates and in natural fumarolic crusts. Although the Au triple alloy is homogeneous on the scale of microns and has a composition close to (Cu,Ni,Zn)3(Au,Ag)2, transmission electron microscopy (TEM) shows that these alloy solid solutions consist of monocrystal domains of Au-Ag, Au-Cu, and possibly Cu2O. Gold occurs in oxide assemblages due to the decomposition of its halogenide complexes under high-temperature conditions (650-870°C). In lower temperature zones (<650°C), Au behavior is related to sulfur compounds whose evolution is strongly controlled by redox state. Other minerals that formed from gas transport and precipitation at Kudryavy volcano include garnet, aegirine, diopside, magnetite, anhydrite, molybdenite, multivalent molybdenum oxides (molybdite, tugarinovite, and ilsemannite), powellite, scheelite, wolframite, Na-K chlorides, pyrrhotite, wurtzite, greenockite, pyrite, galena, cubanite, rare native metals (including Fe, Cr, Mo, Sn, Ag, and Al), Cu-Zn-Fe-In sulfides, In-bearing Pb-Bi sulfosalts, cannizzarite, rheniite, cadmoindite, and kudriavite. Although most of these minerals are fine-grained, they are strongly idiomorphic with textures such as gas channels and lamellar, banded, skeletal, and dendrite-like crystals, characteristic of precipitation from a gas phase. The identified textures and mineral assemblages at Kudryavy volcano can be used to interpret geochemical origins of both ancient and modern ore deposits, particularly gold-rich porphyry and related epithermal systems.

  12. Sources of ore-forming fluid in fumaroles of Kudryavyi Volcano, Kuril islands: Pb isotopic composition of gas condensates and sublimate minerals

    Microsoft Academic Search

    A. V. Chugaev; M. A. Yudovskaya; V. V. Distler; I. V. Chaplygin; A. V. Eremina

    2007-01-01

    Kudryavyi Volcano is an example of the modern ore-forming system related to island-arc andesite volcanism. A direct study of high-temperature gas?hydrothermal process in the volcanic edifice is of fundamental significance for understanding the formation conditions of ore deposits in the modern recycling zones of the oceanic crust. This research was aimed at determining the sources of ore matter during formation

  13. Variability of passive gas emissions, seismicity, and deformation during crater lake growth at White Island Volcano, New Zealand, 2002–2006

    Microsoft Academic Search

    C. Werner; T. Hurst; B. Scott; S. Sherburn; B. W. Christenson; K. Britten; J. Cole-Baker; B. Mullan

    2008-01-01

    We report on 4 years of airborne measurements of CO2, SO2, and H2S emission rates during a quiescent period at White Island volcano, New Zealand, beginning in 2003. During this time a significant crater lake emerged, allowing scrubbing processes to be investigated. CO2 emissions varied from a baseline of 250 to >2000 t d?1 and demonstrated clear annual cycling that

  14. Slope instability induced by volcano-tectonics as an additional source of hazard in active volcanic areas: the case of Ischia island (Italy)

    Microsoft Academic Search

    Marta Della Seta; Enrica Marotta; Giovanni Orsi; Sandro de Vita; Fabio Sansivero; Paola Fredi

    2011-01-01

    Ischia is an active volcanic island in the Gulf of Naples whose history has been dominated by a caldera-forming eruption (ca.\\u000a 55 ka) and resurgence phenomena that have affected the caldera floor and generated a net uplift of about 900 m since 33 ka.\\u000a The results of new geomorphological, stratigraphical and textural investigations of the products of gravitational movements\\u000a triggered by volcano-tectonic events

  15. SLOPE STABILITY ANALYSIS OF THE ILIAMNA VOLCANO, ALASKA, USING ASTER TIR, SRTM DEM, AND AEROMAGNETIC DATA

    E-print Network

    SLOPE STABILITY ANALYSIS OF THE ILIAMNA VOLCANO, ALASKA, USING ASTER TIR, SRTM DEM and digital elevation models to create a hazard index that characterizes slope stability on active volcanoes. Introduction Volcano monitoring in the Aleutians is of great importance due to the heavy amount of airplane

  16. Mechanisms driving polymagmatic activity at a monogenetic volcano, Udo, Jeju Island, South Korea

    Microsoft Academic Search

    Marco BrennaShane; Shane J. Cronin; Ian E. M. Smith; Young Kwan Sohn; Karoly Németh

    2010-01-01

    High-resolution, stratigraphically ordered samples of the Udo tuff cone and lava shield offshore of Jeju Island, South Korea,\\u000a show complex geochemical variation in the basaltic magmas that fed the eruption sequence. The eruption began explosively,\\u000a producing phreatomagmatic deposits with relatively evolved alkali magma. The magma became more primitive over the course of\\u000a the eruption, but the last magma to be

  17. Paleozoic subduction complex and Paleozoic-Mesozoic island-arc volcano-plutonic assemblages in the northern Sierra terrane

    USGS Publications Warehouse

    Hanson, Richard E.; Girty, Gary H.; Harwood, David S.; Schweickert, Richard A.

    2000-01-01

    This field trip provides an overview of the stratigraphic and structural evolution of the northern Sierra terrane, which forms a significant part of the wall rocks on the western side of the later Mesozoic Sierra Nevada batholith in California. The terrane consists of a pre-Late Devonian subduction complex (Shoo Fly Complex) overlain by submarine arc-related deposits that record the evolution of three separate island-arc systems in the Late Sevonian-Early Mississippian, Permian, and Late Triassic-Jurassic. The two Paleozoic are packages and the underlying Shoo Fly Complex have an important bearing on plate-tectonic processes affecting the convergent margin outboard of the Paleozoic Cordilleran miogeocline, although their original paleogeographic relations to North America are controversial. The third arc package represents an overlap assemblage that ties the terrane to North America by the Late Triassic and helps constrain the nature and timing of Mesozoic orogenesis. Several of the field-trip stops examine the record of pre-Late Devonian subduction contained in the Shoo Fly Complex, as well as the paleovolcanology of the overlying Devonian to Jurassic arc rocks. Excellent glaciated exposures provide the opportunity to study a cross section through a tilted Devonian volcano-plutonic association. Additional stops focus on plutonic rocks emplaced during the Middle Jurassic arc magmatism in the terrane, and during the main pulse of Cretaceous magmatism in the Sierra Nevada batholith to the east.

  18. Spatio-temporal evolution of a dispersed magmatic system and its implications for volcano growth, Jeju Island Volcanic Field, Korea

    NASA Astrophysics Data System (ADS)

    Brenna, Marco; Cronin, Shane J.; Smith, Ian E. M.; Sohn, Young Kwan; Maas, Roland

    2012-09-01

    Jeju Island is the emergent portion of a basaltic volcanic field developed over the last c. 1.8 Ma on continental crust. Initial volcanism comprised dispersed, small-volume (< 0.01 km3) alkali basaltic eruptions that incrementally constructed a tuff pile. Lavas and scoria from continuing small-scaled monogenetic volcanism capped this foundation. From c. 0.4 Ma large-volume (> 1 km3) eruptions began, with lavas building a composite shield. Three magma suites can be recognized: Early Pleistocene high-Al alkali (HAA), and Late Pleistocene to Holocene low-Al alkali (LAA) and subalkali (SA). The chemical similarity between small-volume and primitive large-volume eruptions suggests analogous parent magmas and fractionation histories that are independent of erupted volumes. The large-volume magmas evolved to trachyte, which erupted in two distinct episodes: the HAA Sanbangsan suite at c. 750 ka and the LAA Hallasan suite at c. 25 ka. Sr and Nd isotopes indicate that the early trachytes were contaminated by upper crustal material, whereas the later magmas were not. Both suites bear a Nd isotope signature indicative of lower crustal interaction. Sub-suites transitional between HAA and LAA, and between LAA and SA, indicate that melting occurred in discrete, but adjacent, mantle domains. Throughout the evolution of this volcano, each magma batch erupted separately, and a centralized plumbing system was never created. The Island's central peak (Mt. Halla 1950 m a.s.l.) is therefore not a sensu stricto stratovolcano, but marks the point of peak magma output in a distributed magmatic system. Jeju's shape and topography thus represent the spatial variation of fertility of the mantle below it. An increase in melt production in the Late Pleistocene was related to a deepening of the melting zone due to regional tectonic rearrangements. Temporal coincidences between magmatic pulses on Jeju and large-scale caldera eruptive events along the nearest subduction system in Kyushu, Japan, suggest that tectonic extension and changing strain rates may drive volcanism on a regional basis, influencing the intraplate volcanism of Jeju Island.

  19. The Earthscope Plate Boundary Observatory Akutan Alaskan Volcano Network Installation

    NASA Astrophysics Data System (ADS)

    Pauk, B.; Jackson, M.; Mencin, D.; Power, J.; Gallaher, W.; Basset, A.; Kore, K.; Hargraves, Z.; Peterson, T.

    2005-12-01

    During June and July of 2005, the Plate Boundary Observatory (PBO) installed eight permanent GPS stations on Akutan Volcano, in the central Aleutian Islands of Alaska. PBO worked closely with the Alaska Volcano Observatory and the Magmatic Systems Site Selection working group to install stations with a spatial distribution to monitor and detect both short and long term volcanic deformation in response to magmatic intrusions at depth and magma migration through the volcano's conduit system. All eight of the GPS stations were installed by PBO field crews with helicopter support provided by Evergreen Helicopters and logistical support from the Trident Seafood Corporation, the City of Akutan, and the Akutan Corporation. Lack of roads and drivable trails on the remote volcanic island required that all equipment be transported to each site from the village of Akutan by slinging gear beneath the helicopter and internal loads. Each station installed on the volcano consists of a standard short braced GPS monument, two solar panels mounted to an inclined structure, and a six foot high Plaschem enclosure with two solar panels mounted to one of the inclined sides. Each Plaschem houses 24 6 volt batteries that power a Trimble NetRS GPS receiver and one or two Intuicom radios. Data from each GPS receiver is telemetered directly or through a repeater radio to a base station located in the village of Akutan that transmits the data over the internet to the UNAVCO data archive at ftp://data-out.unavco.or/pub/PBO_rinex where it is made freely available to the public.

  20. Volcano Live

    NSDL National Science Digital Library

    John Seach

    Volcano Live contains maps of volcanoes from around the world, a kids' page that provides volcano education links for teachers and students, a volcano glossary, volcano news, links to live video cams of volcanoes, geography and volcano information of countries around the world, and video clips of active volcanoes. There is also information for travelling to volcanoes, a volcano photo section, a section on the destruction of Pompeii, a volcanology section, and volcano safety rules.

  1. Phenocrysts Crystallisation Pressures and Temperatures and Melts Evolution at La Fossa Volcano (Vulcano Island, Italy)

    NASA Astrophysics Data System (ADS)

    Masotta, M.; Trigila, R.

    2008-12-01

    La Fossa Volcano (Vulcano Isl., Aeolian Arch., Italy) erupted last, explosively, in 1888-1890. Its eruptive history includes at least four eruptive cycles of mixed eruptions with strombolian and hydromagmatic phases followed generally by small lava flows ranging in composition from latites to trachytes and rhyolites. Crystallisation temperatures and pressures of phenocrysts and melts chemical evolution, have been modeled via thermochemical calculations and HP-HT laboratory experiments. The crystallisation temperatures and pressures of olivine and clinopyroxene phenocrysts of latitic and trachitic lavas (Punte Nere, Grotte dei Palizzi) were obtained via the empirical olivine-clinopyroxene-liquid thermobarometer of Sugawara (2000) and the olivine geothermometer of Ariskin et al. (1993) which gave consistent values of 1120°C - 60 MPa and 1080°C - 50 MPa. For the trachytic lava of Grotte dei Palizzi and the rhyolitic blocks of 1888-90 eruption, T - P of 1030°C - 50 MPa and 1000°C - 40 MPa were obtained using the two feldspars thermochemical equilibrium model of Green and Usdansky (1986). The %(H2O)m of trachytic and rhyolitic melts, in the range of 1.7 - 2.7% and 2.4 - 2.7% respectively, was obtained after the experimental calibration at P = 100 MPa and T = 1000-1020°C of X(An)plg against the %(H2O)m. The phase relations and melts composition under the above indicated conditions were finally investigated by the MELTS code (Ghiorso and Sack, 1995), allowing us to show how the more primitive latitic melt can evolve toward the more evolved trachytic and rhyolitic compositions.

  2. 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.

  3. GPS monitoring of Hawaiian Volcanoes

    USGS Multimedia Gallery

    The USGS Hawaiian Volcano Observatory uses a variety of ground- and satellite-based techniques to monitor Hawai‘i’s active volcanoes.  Here, an HVO scientist sets up a portable GPS receiver to track surface changes during an island-wide survey of Hawai‘i’s volcanoes. &n...

  4. Lead isotopes behavior in the fumarolic environment of the Piton de la Fournaise volcano (Réunion Island)

    NASA Astrophysics Data System (ADS)

    Vlastélic, I.; Staudacher, T.; Deniel, C.; Devidal, J. L.; Devouard, B.; Finizola, A.; Télouk, P.

    2013-01-01

    The recent activity of the Piton de la Fournaise volcano offers a rare opportunity to address the issue of Pb isotope behavior in volcanic fumaroles, as the composition of the degassing source is accurately and precisely known. Gas sublimates formed between 2007 and 2011 at temperature ranging from 400 to ca. 100 °C include Na-K sulfate (aphthitalite), Ca-Cu sulfate (e.g., gypsum), Na sulfate (thenardite), Ca-Mg-Al-Fe fluoride (e.g., ralstonite) and native sulfur. The high-temperature deposits show trace element patterns typical of volcanic gas (with Pb concentration up to 836 ppm) while the low-temperature deposits are depleted in most volatile elements (Pb <1 ppm) with the exception of Pd and Tl (in fluorides) and Se (in native sulfur). Only for low-temperature fluoride samples do Pb isotope compositions plot significantly outside the field of lavas. The isotopic shift is ascribed to leaching ubiquitous unradiogenic phases (e.g., sulfides) by acidic gas condensates. The similarity in Pb isotope signature between lavas and sublimate samples more representative of the gas phase (sulfates) indicates that the net fractionation of Pb isotopes resulting from volatilization and condensation processes is smaller than the precision of Pb isotope measurements (better than 60 ppm/a.m.u.). The absence of net fractionation could result from negligible isotope fractionation during Pb volatilization followed by extensive condensation of gaseous Pb, with possibly significant isotopic fractionation at this stage. Although this scenario has to be refined by more direct measurement of the gas phase, and its general applicability tested, it suggests that a small fraction (<10%) of initially volatilized Pb ultimately escapes to the atmosphere, while the remaining dominant fraction is trapped in sublimates. As sublimates are rapidly dissolved and entrained by runoff, the fumarolic environment appears as a factory efficiently transferring isotopically unfractionated Pb from magmas towards the hydrological system and seawater. Resolving very small isotopic differences between magmas and their gaseous products remains an analytical challenge. High-precision Pb isotope measurements rest not only on instrumental performance but also on high-yield chemistry, as Pb isotopes drastically fractionate (800 ppm/a.m.u.) upon elution on anionic resin. For 50% Pb recovery, the estimated isotopic bias is plus or minus 60-80 ppm/a.m.u., depending on which of the early (isotopically light) or late (isotopically heavy) Pb fraction is lost.

  5. The September 1988 intracaldera avalanche and eruption at Fernandina volcano, Galapagos Islands

    USGS Publications Warehouse

    Chadwick, W.W., Jr.; De Roy, T.; Carrasco, A.

    1991-01-01

    During 14-16 September 1988, a large intracaldera avalanche and an eruption of basaltic tephra and lava at Fernandina volcano, Galapagos, produced the most profound changes within the caldera since its collapse in 1968. A swarm of eight earthquakes (mb 4.7-5.5) occurred in a 14 h period on 24 February 1988 at Fernandina, and two more earthquakes of this size followed on 15 April and 20 May, respectively. On 14 September 1988, another earthquake (mb 4.6) preceded a complex series of events. A debris avalanche was generated by the failure of a fault-bounded segment of the east caldera wall, approximately 2 km long and 300 m wide. The avalanche deposit is up to 250 m thick and has an approximate volume of 0.9 km3. The avalanche rapidly displaced a preexisting lake from the southeast end of the caldera floor to the northwest end, where the water washed up against the lower part of the caldera wall, then gradually seeped into the avalanche deposit and was completely gone by mid-January 1989. An eruption began in the caldera within about 1-2 h of the earthquake, producing a vigorous tephra plume for about 12 h, then lava flows during the next two days. The eruption ended late on 16 September. Most of the eruptive activity was from vents on the caldera floor near the base of the new avalanche scar. Unequivocal relative timing of events is difficult to determine, but seismic records suggest that the avalanche may have occurred 1.6 h after the earthquake, and field relations show that lava was clearly erupted after the avalanche was emplaced. The most likely sequence of events seems to be that the 1988 feeder dike intruded upward into the east caldera wall, dislocated the unstable wall block, and triggered the avalanche. The avalanche immediately exposed the newly emplaced dike and initiated the eruption. The exact cause of the earthquakes is unknown. ?? 1991 Springer-Verlag.

  6. The behaviour of the shallow plumbing system at la Fournaise volcano (Reunion island). A petrological approach.

    NASA Astrophysics Data System (ADS)

    Boivin, P.; Bachelery, P.

    2003-04-01

    Since 1981, the lava flows of Piton de la Fournaise have been regularly sampled during each eruption and their temperature has been simultaneously measured. Work presented here mainly uses this data base and covers the period 1977-1998. For this period, several types of eruption occurred. In 1977, a volume of 12 million of cubic meters of "oceanite" was emitted by a fissure opened on the outside of the Enclos Fouque caldera. Then, most of the eruptions were localised in the Enclos caldera, except that of March 1986 during which a crack reaching the sea level opened on the external slopes of the volcano. In 1998 two vents functioned simultaneously, each one emitting a magma of different nature. All lavas, except the "oceanite" of 1977, are transitional basalts rather poor in phenocrysts (Ol, Cpx, Pl) and little differentiated. Their composition coincides with that most frequently observed for the whole of the Piton de la Fournaise historical lavas. Nevertheless, the detailed study of their composition and minerals, according to the date of the eruption as well as during each eruption, allows to make the following observations: - On the basis of their composition, in particular of their potassium content, three different magmas were emitted from 1977 to 1998. The first (high K #1) was emitted from 1977 to 1987, the second (low K) from 1988 to 1998 and the third (high K #2) simultaneously with the second, in 1998. - Over a period of about 10 years the first two magmas, slowly differentiated by fractional crystallization. - At the same time, they underwent a contamination by the hydrothermalized surrounding rocks, as revealed by oxygen isotopes and oxidation states. - The presence of two populations of clinopyroxene shows that these magmas evolved at two different levels. The first, at intermediate depth, was characterized by a relatively slow crystallization, while the second, at sub-surface level, was marked by a faster cooling. The whole data set suggests that the feeding system of the Piton de la Fournaise comprises two storage levels, one at intermediate depth, the other very close to surface. The latter is presumably made of a network of more or less inter-connected dykes and sills. Within these "staged" reservoirs, the different magmas were simultaneously present without possibility of mixture, and they evolved in parallel by fractional crystallization. The whole storage system functions like a single cooling unit.

  7. Volcano seismicity in Alaska

    NASA Astrophysics Data System (ADS)

    Buurman, Helena

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

  8. Improved three-dimensional models of seismic velocity and sensity for the island of Hawaii: Implications for volcano-tectonics

    NASA Astrophysics Data System (ADS)

    Park, Jaewoo

    Improved 3-D models of P-wave velocity and density are presented for better understanding of volcano-tectonic processes around the Island of Hawaii. The summit and upper rift zones of Kilauea are underlain by high-velocity and positive-density anomalies, indicative of magma intrusives dominated by dikes and melt-rich olivine cumulates. Seismicity is clustered at the seaward edge of this body, indicating that the cumulate body pushes the flank outward above a frictional decollement. The intrusive rocks along Kilauea's and Mauna Loa's rift zones are not continuous along their lengths, suggesting that eruptions along the lower rift zones could be fed vertically from the mantle, rather than downrift from the summit reservoirs. Mauna Loa's southeast flank is underlain by an anomalously large volume of intrusive materials that lacks the distinctive positive density anomaly observed above active rift zones. Therefore, this cumulate body is probably now cold and solidified, representing an ancient rift zone. Similar to Kilauea, earthquakes are concentrated along the boundary of this body, but here accommodate seaward motion of the adjacent flank rather than the cumulate body. Mauna Loa also appears to have a buried northwest rift zone, overlying the older flanks of Hualalai and Mauna Kea. Both Hualalai and Mauna Kea show south trending high-velocity and density features, also indicative of buried rift zones. High- and low-velocity anomalies beneath Loihi seamount are interpreted to indicate the presence of intrusive cumulates within the volcanic edifice and oceanic crust, and partial melt within the upper mantle, respectively. Low velocities beneath the Hilina and Kao'iki fault zones are attributed to thick piles of volcaniclastic sediments deposited on the submarine flanks. In contrast, the submarine outer bench of Kilauea is marked by anomalously high-velocity materials, possibly evidence for a buried seamount that may impede outward spreading of the flank today.

  9. High Resolution, Pb Isotope Variability Within Historic Eruptions of the Cumbre Vieja Volcano, La Palma, Canary Islands

    NASA Astrophysics Data System (ADS)

    Locke, J. A.; Peterson, B. T.; Nelson, B. K.

    2005-12-01

    The range of time-scales over which ocean island basalt (OIB) magmatism taps different mantle heterogeneities is a fundamental dynamic of mantle plumes. The variability of long-lived radiogenic isotopes in OIB magmas erupted on time scales less than 100 years has been addressed primarily for Hawaiian magmas (e.g., Pietruszka et al., 2001). Similar data are relatively sparse for hot spots with low buoyancy fluxes. The Canary Islands have low eruption rates and have been historically active. The Cumbre Vieja volcano in southern La Palma, Canary Islands, has six, well-mapped, historic eruptions spanning the entire southern rift zone. We have investigated Pb isotope compositional variations expressed in magmas erupted in a series of events spanning 500 years (the 1480, 1585, 1677, 1712, 1949, and 1971 eruptions), and sampled in detail two of these events (the 1677 and 1712 eruptions) to document isotopic variability at the month to year time-scale as well as the 100-year time scale. Previous Pb isotope investigations of Cumbre Vieja did not reveal systematic variations (e.g., Marcantonio et al., 1995 and Ovchinnikova et al., 1995). With denser sampling (40 samples) and higher precision MC-ICP-MS analyses, we observe that radiogenic Pb isotope compositions over the 500 year eruptive history decrease systematically with time (206Pb/204Pb =19.669 -- 19.611, 207Pb/ 204Pb = 15.618 -- 15.602, 208Pb/204Pb = 39.530 -- 39.430). Detailed Pb isotope analyses of the 1677 and 1712 eruptions indicate isotopically homogeneous magmas within a single eruptive episode. However, samples from both the 1677 and 1712 eruptions display mineralogic evidence for magma mixing: 1677 samples include isotopically distinct gabbroic xenoliths, and both magmas have reversely- zoned clinopyroxene phenocrysts with corroded cores of Na-rich salite, and zoned overgrowths of Al-rich salite. With time, an increasing proportion of partial melt from a less radiogenic end-member within a heterogeneous plume explains the 500 year trend. Alternatively, higher level mixing of two magmas would require sequential recharge of a single magma chamber that feeds the entire rift zone. A single chamber is structurally unlikely, and not consistent with geochemical and petrographic trends (Klü gel, 1999). From the decompressing plume, batches of melt with homogeneous Pb isotope ratios are extracted periodically. To generate mineralogic disequilibrium, each batch must segregate into a zoned magma chamber or multiple, isolated pockets and differentiate at multiple levels. Prior to eruption, magma from these pockets may remix, producing reversely-zoned clinopyroxene phenocrysts. Isotopic homogeneity is preserved within a given magma batch. In the Canary Islands, the minimum time period for eruptive basalts to reflect resolvable mantle isotope heterogeneity is on the order of 50 - 100 years. A. Klügel, K. A. Hoernle, H.-U. Schmincke, J. D. L. White, J. Geophys. Res. 105(B3), 5997 (2000). F. Marcantonio, A. Zindler, T. R. Elliot, H. Staudigel, Earth Planet. Sci. Lett. 133, 397 (1995). G. V., Ovchinnikova, B. V., Belyatskii, I. M., Vasil'eva, L. K., Levsky, A. F., Grachev, V., Arana, I. J., Mitjavila, Petrologiya, 3, 195 (1995). A. J. Pietruszka, K. H. Rubin, M. O. Garcia, Earth Planet. Sci. Lett. 186, 15 (2001).

  10. At-sea observations of marine birds and their habitats before and after the 2008 eruption of Kasatochi volcano, Alaska

    USGS Publications Warehouse

    Drew, G.S.; Dragoo, D.E.; Renner, M.; Piatt, J.F.

    2010-01-01

    Kasatochi volcano, an island volcano in the Aleutian chain, erupted on 7-8 August 2008. The resulting ash and pyroclastic flows blanketed the island, covering terrestrial habitats. We surveyed the marine environment surrounding Kasatochi Island in June and July of 2009 to document changes in abundance or distribution of nutrients, fish, and marine birds near the island when compared to patterns observed on earlier surveys conducted in 1996 and 2003. Analysis of SeaWiFS satellite imagery indicated that a large chlorophyll-a anomaly may have been the result of ash fertilization during the eruption. We found no evidence of continuing marine fertilization from terrestrial runoff 10 months after the eruption. At-sea surveys in June 2009 established that the most common species of seabirds at Kasatochi prior to the eruption, namely crested auklets (Aethia cristatella) and least auklets (Aethia pusilla) had returned to Kasatochi in relatively high numbers. Densities from more extensive surveys in July 2009 were compared with pre-eruption densities around Kasatochi and neighboring Ulak and Koniuji islands, but we found no evidence of an eruption effect. Crested and least auklet populations were not significantly reduced by the initial explosion and they returned to attempt breeding in 2009, even though nesting habitat had been rendered unusable. Maps of pre- and post-eruption seabird distribution anomalies indicated considerable variation, but we found no evidence that observed distributions were affected by the 2008 eruption. ?? 2010 Regents of the University of Colorado.

  11. 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.

  12. 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.

  13. Evaluation of noise level and site response at Mt. Etna volcano and Aeolian Islands

    NASA Astrophysics Data System (ADS)

    D Amico, S.; Giampiccolo, E.; Maiolino, V.; Patanè, D.; Ursino, A.

    2003-04-01

    The aim of this work was to test the quality of the sites where the stations of the INGV-CT seismic network are installed. This because most of the installations will be soon improved with new broad-band sensors, which require a low level of background noise. Therefore, we investigated the noise level and estimated the site response at the seismic stations deployed at Mt. Etna and at Aeolian Islands, in order to evidence possible disturbs which can be related to anthropic activity, environmental factors and/or to the local soil conditions. Noise measurements were carried out using a portable digital seismic station equipped with a 3-component, 20 s sensor. The acquisition was performed both inside the vault structures where the remote stations are located and in proximity of them, on the outcropping terrain. The noise spectra were compared with the NLNM (New Low Noise Model) and NHNM (New High Noise Model) models described by Peterson (1993). A preliminary estimate of site response at each station, by applying the Nakamura (1989) technique, was also performed. The obtained results show, for some stations, higher noise levels mainly due to volcanic tremor and/or bad soil conditions. Moreover, in several cases, vault design need to be deeply reviewed and for some installations the substitution of the sites is required. References Nakamura, Y., (1989). A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Quarterly R of Report RTRI, 30, 25-33. Peterson, J., (1993). Observations and modelling of background seismic noise. Open File Report 93-322, U. S. Geological Survey, Albuquerque, NM.

  14. Submarine Volcanic Cones in the Central Aleutian Arc: Relationship to Arc Rifting and Oblique Plate Convergence

    NASA Astrophysics Data System (ADS)

    Reynolds, J. R.; Greene, G.; Krutikov, L.; Vallier, T. L.

    2004-12-01

    Plate convergence along the 2200km Aleutian Arc varies from orthogonal at the Alaskan Peninsula to fully strike-slip on the west end of the arc. Deformation response of the upper plate to oblique convergence appears to accelerate markedly between Adak (177W) and Amchitka Pass (180W). On a regional scale, this deformation appears to be concentrated at the boundaries of crustal blocks, with clockwise rotation and westward translation [Geist et al., Tectonics 7, 327-341, 1988]. In the block rotation model, extensional rift structures develop between the blocks in arc-normal orientation. Summit basins develop at the northern, trailing edge of the blocks in arc-parallel orientation. These summit basins are located near or within the volcanic front. Thus structures in the upper plate driven by oblique convergence are predicted to interact with arc volcanism. We report on multibeam mapping in 2003-2004 and ROV Jason II dives in 2004. The data reveal locations and patterns of fault structures, volcanic cones, and lithologies in several locations critical to understanding the arc's response to oblique convergence. A large submarine volcano, named Amchixtam Chaxsxii in the Unangan language, was mapped next to Semisopochnoi Island. Additional small cones are identified on the flank of Tanaga Volcano, and near Bobrof Volcano on possible fault structures. The largest extensional `block boundary' is located at Amchitka Pass; in this area the seafloor is offset by a network of faults. Small volcanic cones are clustered at these faults. Some show signs of erosion and mass wasting; others, especially deeper ones, are intact. Surfaces are dominated by `a`a flows and spatter, and have light sediment cover and moderately fresh lavas. Our mapping focused on specific sites that were chosen to be representative, and suggests that (1) small, probably monogenetic cones are common; (2) the cones occur preferentially in areas of extensional faulting in the volcanic front; (3) these cones are present largely because of oblique convergence and arc deformation. Geochemical analyses will test their relationship to nearby subaerial arc volcanoes.

  15. Buldir Depression - A Late Tertiary graben on the Aleutian Ridge, Alaska

    USGS Publications Warehouse

    Marlow, M. S.; Scholl, D. W.; Buffington, E.C.; Boyce, R.E.; Alpha, T.R.; Smith, P.J.; Shipek, C.J.

    1970-01-01

    Buldir Depression is a large, rectilinear basin that lies on the northern edge of the Aleutian Ridge and is aligned with the arcuate chain of active volcanoes on the ridge crest. The depression appears to be a volcanic-tectonic feature, which began to form in Late Tertiary time and which is still forming. It is a graben formed by extensional rifting and accompanied by contemporaneous volcanism on the Aleutian Ridge. Subsidence rates for the depression are estimated at 20-70 cm/1,000 years. Sediments in the depression are 300 m thick and are probably pelagic and turbidite deposits of Pleistocene age. The turbidites were apparently derived from the plateau area of the Aleutian Ridge surrounding the depression. Older sediments on the northern slope of the Aleutian Ridge have a maximum thickness of 550 m and are deformed and slumped toward the Bering Sea. These sediments are postulated to overlie a mid-flank terrace on the northern Aleutian Ridge that titled to the north during the formation of Buldir Depression. ?? 1970.

  16. An investigation of the distribution of eruptive products on the shield volcanoes of the western Galapagos Islands using remotely sensed data

    NASA Technical Reports Server (NTRS)

    Munro, Duncan C.; Rowland, Scott K.; Mouginis-Mark, Peter J.; Wilson, Lionel; Oviedo-Perez, Victor-Hugo

    1991-01-01

    Recent volcanic activity in the Galapagos Islands is concentrated on the two westernmost islands, Isla Isabela and Isla Fernandina. Difficult access has thus far prevented comprehensive geological field studies, so we examine the potential of remotely sensed data as a means of studying volcanic processes in the region. Volcan Wolf is used as an example of the analysis of SPOT HRV-1 data undertaken for each volcano. Landsat TM data are analyzed in an attempt to construct a relative age sequence for the recent eruptive activity on Isla Fernandina. No systematic variation in the surface reflectance of lava flows as a function of age could be detected with these data. Thus it was not possible to complete a study of the temporal distribution of volcanic activity.

  17. 2006 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.; Manevich, Alexander; Rybin, Alexander

    2008-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest at or near nine separate volcanic centers in Alaska during 2006. A significant explosive eruption at Augustine Volcano in Cook Inlet marked the first eruption within several hundred kilometers of principal population centers in Alaska since 1992. Glaciated Fourpeaked Mountain, a volcano thought to have been inactive in the Holocene, produced a phreatic eruption in the fall of 2006 and continued to emit copious amounts of volcanic gas into 2007. 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.

  18. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2014-10-01 2014-10-01 false Hawaii-Aleutian zone. 71.12 Section 71...STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes...

  19. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 2012-10-01 false Hawaii-Aleutian zone. 71.12 Section 71...STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes...

  20. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 2010-10-01 false Hawaii-Aleutian zone. 71.12 Section 71...STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes...

  1. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 false Hawaii-Aleutian zone. 71.12 Section 71...STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes...

  2. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 2013-10-01 false Hawaii-Aleutian zone. 71.12 Section 71...STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes...

  3. Lab7: Volcanoes I. --Their Geographic Distribution Introduction

    E-print Network

    Chen, Po

    1 Lab7: Volcanoes I. -- Their Geographic Distribution Introduction Active volcanoes present in understanding these hazards is to realize where active volcanoes actually occur on the Earth's surface. Pacuritin Volcano, Mexico Active Volcanoes of the World South Sandwich Islands. Also known as the Scotia arc

  4. Slope instability induced by volcano-tectonics as an additional source of hazard in active volcanic areas: the case of Ischia island (Italy)

    NASA Astrophysics Data System (ADS)

    Della Seta, Marta; Marotta, Enrica; Orsi, Giovanni; de Vita, Sandro; Sansivero, Fabio; Fredi, Paola

    2012-01-01

    Ischia is an active volcanic island in the Gulf of Naples whose history has been dominated by a caldera-forming eruption (ca. 55 ka) and resurgence phenomena that have affected the caldera floor and generated a net uplift of about 900 m since 33 ka. The results of new geomorphological, stratigraphical and textural investigations of the products of gravitational movements triggered by volcano-tectonic events have been combined with the information arising from a reinterpretation of historical chronicles on natural phenomena such as earthquakes, ground deformation, gravitational movements and volcanic eruptions. The combined interpretation of all these data shows that gravitational movements, coeval to volcanic activity and uplift events related to the long-lasting resurgence, have affected the highly fractured marginal portions of the most uplifted Mt. Epomeo blocks. Such movements, mostly occurring since 3 ka, include debris avalanches; large debris flows (lahars); smaller mass movements (rock falls, slumps, debris and rock slides, and small debris flows); and deep-seated gravitational slope deformation. The occurrence of submarine deposits linked with subaerial deposits of the most voluminous mass movements clearly shows that the debris avalanches impacted on the sea. The obtained results corroborate the hypothesis that the behaviour of the Ischia volcano is based on an intimate interplay among magmatism, resurgence dynamics, fault generation, seismicity, slope oversteepening and instability, and eruptions. They also highlight that volcano-tectonically triggered mass movements are a potentially hazardous phenomena that have to be taken into account in any attempt to assess volcanic and related hazards at Ischia. Furthermore, the largest mass movements could also flow into the sea, generating tsunami waves that could impact on the island's coast as well as on the neighbouring and densely inhabited coast of the Neapolitan area.

  5. Sumisu volcano, Izu-Bonin arc, Japan: site of a silicic caldera-forming eruption from a small open-ocean island

    NASA Astrophysics Data System (ADS)

    Tani, Kenichiro; Fiske, Richard S.; Tamura, Yoshihiko; Kido, Yukari; Naka, Jiro; Shukuno, Hiroshi; Takeuchi, Rika

    2008-03-01

    Sumisu volcano was the site of an eruption during 30 60 ka that introduced ˜48 50 km3 of rhyolite tephra into the open-ocean environment at the front of the Izu-Bonin arc. The resulting caldera is 8 × 10 km in diameter, has steep inner walls 550 780 m high, and a floor averaging 900 m below sea level. In the course of five research cruises to the Sumisu area, a manned submersible, two ROVs, a Deep-Tow camera sled, and dredge samples were used to study the caldera and surrounding areas. These studies were augmented by newly acquired single-channel seismic profiles and multi-beam seafloor swath-mapping. Caldera-wall traverses show that pre-caldera eruptions built a complex of overlapping dacitic and basaltic edifices, that eventually grew above sea level to form an island about 200 m high. The caldera-forming eruption began on the island and probably produced a large eruption column. We interpret that prodigious rates of tephra fallback overwhelmed the Sumisu area, forming huge rafts of floating pumice, choking the nearby water column with hyperconcentrations of slowly settling tephra, and generating pyroclastic gravity currents of water-saturated pumice that traveled downslope along the sea floor. Thick, compositionally similar pumice deposits encountered in ODP Leg 126 cores 70 km to the south could have been deposited by these gravity currents. The caldera-rim, presently at ocean depths of 100 400 m, is mantled by an extensive layer of coarse dense lithic clasts, but syn-caldera pumice deposits are only thin and locally preserved. The paucity of syn-caldera pumice could be due to the combined effects of proximal non-deposition and later erosion by strong ocean currents. Post-caldera edifice instability resulted in the collapse of a 15° sector of the eastern caldera rim and the formation of bathymetrically conspicuous wavy slump structures that disturb much of the volcano’s surface.

  6. Volcanic Unrest of Fogo Volcano in 2011-2012, S.Miguel Island, Azores, Observed by Continuous and Campaign GPS Analysis

    NASA Astrophysics Data System (ADS)

    Okada, Jun; Sigmundsson, Freysteinn; Ofeigsson, Benedikt; Ferreira, Teresa; Gaspar, Joao; Lorenzo, Maria; Araujo, Joao; Rodriques, Rita

    2014-05-01

    Volcanic eruptions can occur after long time of dormancy as has been seen from the recent examples: Mount St. Helens 1980, Pinatubo 1991, Unzen 1991, Soufrière Hills volcano 1995, Chaitén 2008, and Eyjafjallajökull 2010. By utilizing space geodesy techniques, namely GNSS and InSAR, it has been reported that the inflation-deflation processes exist at several dormant volcanoes in the world, but the mechanism responsible for this phenomena is still controversial. Fundamental questions such as magma vs. hydrothermal fluids and volcanic vs. tectonic process remain unanswered in many cases. In this study, we analyze both continuous and campaign GPS data from Fogo volcano, S. Miguel Island, Azores. Although no geochemical and hydrothermal evidences for a magmatic intrusion were reported during the past seismic swarm episodes (1989, 2003-2006, and 2011-2012), geophysical data, both seismic and ground deformation, indicate possible volcanic sources. GPS time series spanned 2008-2013 period characterize tectonic plate divergence between Eurasian and Nubian, and reveal two different types of ground deformation associated with the 2011-2012 volcanic unrest of Fogo. One is the permanent edifice-scale inflation centered at NE summit which corresponds to the increase of volcano-tectonic events. Another is the subsequent minor-scale inflation-deflation reversals between Congro, a trachyte maar, east of Fogo and Furnas volcano. Calculated strain rates and GPS campaign results indicate that the 2011-2012 deformation is one order smaller than the previous unrest episode. A strong similarity exists to Matsushiro earthquake swarm (1965-1966) and Campi Flegrei volcanic unrests (1969-1972 and 1982-1984), which is the coexistence of an edifice-scale main inflation associated with intense volcano-tectonic earthquakes with inflation to deflation reversal that coincided with a sharp drop of seismicity. High recovery rate of inflation-deflation may be an indicator for the existence of hydrothermal fluids in the highly heterogeneous/porous media. We propose the following hypothesis for the 2011-2012 volcanic unrest of Fogo - (1) a minor magmatic intrusion beneath Fogo which acts as a heat source encourages lateral diffusion of fluids, (2) the fluids are transported through the existing cracks/fissures which are sustained by regional extension due to plate divergence, (3) influx of fluids increases pressure in cracks/fissures and generates lower-frequency earthquakes, and (4) discharge of fluids causes sudden pressure decrease and dilatancy recovery which leads seismic quiescence. Fogo volcano represents 450 years of dormancy since 1563-1564 when the last eruptions took place at the summit caldera. However, we show that the volcano has been experiencing intermittent magma ascents (i.e. repeating "failed eruptions") even its dormant period. Further researches are needed in order to understand the eruption triggering conditions. Nevertheless, we have a continuous GPS network that can detect small changes in the volcano roots and provide important contribution to evaluate future unrest episodes at Azores.

  7. Earth's Active Volcanoes by Geographic Region

    NSDL National Science Digital Library

    This site describes active volcanoes from around the world by using the volcano links from the Michigan Technological University and the homepages of observatories at active volcanoes. Each volcano section contains photo images, maps, and reference text. Some sections contain bibliographies, volcano reports, and video clips of lahars. The volcanoes are organized by the following geographic regions: Africa and surrounding islands; the Southwest Pacific, Southeast Asia, and India; East Asia including Japan and Kamchatka; Antarctica; the North Atlantic and Iceland; the Mediterranean; South America and surrounding islands; Central Pacific, South Pacific and New Zealand; Alaska and the Northern Pacific Region; North America; and Central America.

  8. Systematic Search for Background Seismicity Rate Changes and Correlations at Alaskan Volcanoes

    Microsoft Academic Search

    K. R. Kore; S. R. McNutt; D. H. Christensen

    2004-01-01

    Recent studies have noted a correlation between large earthquakes and localized seismicity rate changes, particularly those associated with volcanic systems. In this study, we analyzed the Alaska Volcano Observatory (AVO) seismicity catalog from late 1989 through mid-2004 for patterns of background seismicity rate changes at the individual monitored volcanoes throughout the Aleutian Arc. We expand the recent studies to include

  9. The Importance of Long-Term Studies of Ecosystem Reassembly after the Eruption of the Kasatochi Island Volcano

    E-print Network

    del Moral, Roger

    , Washington 98195, U.S.A. moral@uw.edu Abstract Kasatochi Island is a small volcanic island in the central will hasten early recovery, but significant erosion (removal of tephra and marine sediments) must occur detail immediate impacts of the Kasatochi Island volcanic eruption on its biota and geomorphology

  10. Genetic and archaeological evidence for a former breeding population of Aleutian Cackling Goose

    E-print Network

    Kemp, Brian M.

    recovered from the Zeto Point archaeological site (ADK-011) on Adak Island in the central Aleutians, Alaska'oies de taille moyenne au site archéologique Zeto Point (ADK-011) sur l'île d'Adak dans les Aléoutiennes on Adak Island, known as Zeto Point (ADK-011), in the central Aleu- tians, Alaska (Fig. 1). Three species

  11. Monitoring for volcano-hydrothermal activity using continuous gravity and local ground acceleration measurements: New deployments at Inferno Crater, Waimangu and White Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Jolly, Arthur; Fournier, Nico; Cole-Baker, Jeremy; Miller, Craig

    2010-05-01

    Volcanoes with crater lakes are often characterised by shallow hydrothermal systems which display cyclic behaviour (temperature, lake level, chemistry, etc.) and shallow seismic tremor. Present monitoring programmes in New Zealand include routine collection of these observables, but the associated shallow sub-surface processes are still inadequately modelled and poorly understood. Models would be better constrained with the incorporation of additional geophysical parameters. To this end, we have established a new test programme to continuously monitor for micro-gravity variations at New Zealand volcanoes. We utilise a Micro-g-LaCoste gPhone relative gravity meter having 1 Hz sample rate and a measurement precision of 1 microgal to test the viability of gravity monitoring for volcano-hydrothermal systems. We have initially tested the new sensor in a short term deployment (~2 months) at Inferno Crater, Waimangu, New Zealand. Inferno shows dramatic variations in crater lake level (> 7 m range), temperature (>40o C range) and hydrothermally derived tremor, all over a period of ~5 weeks. The amplitude and period of these observables are ideal for testing gravity variations associated with a cycling hydrothermal system because several cycles can be obtained in a relatively short campaign. We have deployed the gravity sensor into a buried vault having a stable concrete base to minimise local environmental influences. This vault is located ~20 meters from Inferno Lake edge (at high stand) and offers sufficient noise reduction to measure the gravitational effects associated with lake level changes. We will show results for the new gravity meter including raw relative gravity measurements and first order corrections (earth-tide, ocean loading, sensor level, temperature, and barometric pressure) to obtain both residual gravity and overprinted local ground accelerations (earthquakes and local tremor). To examine the effects of local ground vibrations on the gravity meter, we have co-located a broadband seismometer (100 Hz sample rate). Of particular interest in this analysis is the separation of any microgravity changes from the hydrothermal tremor signature. Future modelling of the Inferno Crater lake will incorporate gravity, lake level and temperature changes into a multi-phase spatio-temporal model of the subsurface. We anticipate that separation of the gravity and seismic signals may allow future constraint of the sub-surface hydrothermal processes which control cyclic behaviour. We also will show results of a planned deployment of the new gravity meter to White Island volcano, New Zealand which will occur in March 2010. Lessons learned from the Waimangu deployment will be incorporated to understand the long-term variations of White Islands' hydrothermal and magmatic system.

  12. Tephra Studies by the Alaska Volcano Observatory: Present and Future Research

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Wallace, K. L.

    2004-12-01

    Tephra from Aleutian arc volcanoes constitutes an important volcanic hazard for Alaska, western Canada, and some parts of the conterminous U.S. where even small amounts of airborne ash may have dire consequences for jet aircraft traversing North Pacific and western U.S. air routes. Motivated by the need to address volcanic ash hazards on a regional scale, we have initiated a program of tephra studies within the auspices of the Alaska Volcano Observatory (AVO) of the U.S. Geological Survey. A concentrated focus on tephra problems and a new laboratory facility within AVO will help facilitate studies of Quaternary age tephra at Alaskan volcanoes by providing a regional center for laboratory analyses of volcanic ash and standardized web-based reporting and archiving of tephra data. In its first year of operation, the laboratory has been engaged in research at Veniaminof, Mt. Spurr, and Augustine volcanoes, has sponsored research on Holocene tephra deposits of upper Cook Inlet, and has initiated analytical studies of tephra deposits on Adak and Kanaga Islands in the western Aleutians. The objective of these studies is to develop multiparameter techniques for characterization and correlation of tephra deposits, establish radiocarbon-controlled tephrostratigraphic frameworks, and to evaluate the magnitude and frequency of tephra-producing eruptions. In the upper Cook Inlet region of Alaska, we and our colleagues have begun developing a comprehensive record of ash fall by systematically selecting and coring shallow lakes and evaluating the tephra preserved in the lacustrine sediment. Sediment cores from these lakes contain numerous tephra deposits of Holocene age in datable context that can be correlated with proximal tephra deposits on the flanks of their source volcanoes. By combining tephra data from lacustrine deposits and natural exposures we hope to develop a robust geologic catalog of tephra deposits that will enable long-distance correlation of tephras, provide greater detail on the chronology of eruptions, and establish a longer-term context for tephra hazards. Future work will be focused on improving correlation of tephras, identification of source volcanoes, developing reference datasets, and developing a web-served database of tephra data.

  13. 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.

  14. A new model for the growth of basaltic shields based on deformation of Fernandina volcano, Galápagos Islands

    USGS Publications Warehouse

    Bagnardi, Marco; Amelung, Falk; Poland, Michael P.

    2013-01-01

    Space-geodetic measurements of surface deformation produced by the most recent eruptions at Fernandina – the most frequently erupting volcano in the Galápagos Archipelago – reveal that all have initiated with the intrusion of subhorizontal sills from a shallow magma reservoir. This includes eruptions from fissures that are oriented both radially and circumferentially with respect to the summit caldera. A Synthetic Aperture Radar (SAR) image acquired 1–2 h before the start of a radial fissure eruption in 2009 captures one of these sills in the midst of its propagation toward the surface. Galápagos eruptive fissures of all orientations have previously been presumed to be fed by vertical dikes, and this assumption has guided models of the origin of the eruptive fissure geometry and overall development of the volcanoes. Our findings allow us to reinterpret the internal structure and evolution of Galápagos volcanoes and of similar basaltic shields. Furthermore, we note that stress changes generated by the emplacement of subhorizontal sills feeding one type of eruption may control the geometry of subsequent eruptive fissures. Specifically, circumferential fissures tend to open within areas uplifted by sill intrusions that initiated previous radial fissure eruptions. This mechanism provides a possible explanation for the pattern of eruptive fissures that characterizes all the western Galápagos volcanoes, as well as the alternation between radial and circumferential fissure eruptions at Fernandina. The same model suggests that the next eruption of Fernandina will be from a circumferential fissure in the area uplifted by the 2009 sill intrusion, just southwest of the caldera rim.

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

    USGS Publications Warehouse

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

    2005-01-01

    Within the Commonwealth of the Northern Mariana Islands (CNMI), Anatahan is one of nine active subaerial volcanoes that pose hazards to major air-traffic routes from airborne volcanic ash. The 2003-2004 eruptive activity of Anatahan volcano affected the region's aviation operations for 3 days in May 2003. On the first day of the eruption (10 May 2003), two international flights from Saipan to Japan were cancelled, and several flights implemented ash-avoidance procedures. On 13 May 2003, a high-altitude flight through volcanic gas was reported, with no perceptible damage to the aircraft. TOMS and MODIS analysis of satellite data strongly suggests that no significant ash and only minor amounts of SO2 were involved in the incident, consistent with crew observations. On 23 May 2003, airport operations were disrupted when tropical-cyclone winds dispersed ash to the south, dusting Saipan with light ashfall and causing flight cancellations there and at Guam 320 km south of the volcano. Operational (near-real-time) monitoring of ash clouds produced by Anatahan has been conducted since the first day of the eruption on 10 May 2003 by the Washington Volcanic Ash Advisory Center (VAAC). The VAAC was among the first groups outside of the immediate area of the volcano to detect and report on the unexpected eruption of Anatahan. After being contacted about an unusual cloud by National Weather Service forecasters in Guam at 1235 UTC on 10 May 2003, the VAAC analyzed GOES 9 images, confirming Anatahan as the likely source of an ash cloud and estimating that the eruption began at about 0730 UTC. The VAAC issued its first Volcanic Ash Advisory for Anatahan at 1300 UTC on 10 May 2003 more than 5 h after the start of the eruption, the delay reflecting the difficulty of detecting and confirming a surprise eruption at a remote volcano with no in situ real-time geophysical monitoring. The initial eruption plume reached 10.7-13.4 km (35,000-44,000 ft), well into jet cruise altitudes; thereafter, the maximum plume height decreased and during the rest of the eruption usually did not exceed ???5 km (???17,000 ft), which lessened the potential hazard to aircraft at higher cruise altitudes. Drifting ash clouds commonly extended hundreds of kilometers from the volcano, occasionally as far west as the Philippines. Over the course of the eruptive activity in 2003-2004, the VAAC issued 323 advisories (168 with graphical depictions of ash clouds) for Anatahan, serving as a reliable source of ash-cloud information for aviation-related meteorological offices and air carriers. With a record of frequent eruptions in the CNMI, continued satellite and in situ real-time geophysical monitoring is needed at Anatahan and other Marianas volcanoes so that potential hazards to aviation from any future eruptive activity can be quickly and correctly assessed. ?? 2005 Elsevier B.V. All rights reserved.

  16. Volcanoes Galore!

    NSDL National Science Digital Library

    Mr. Syracuse

    2008-06-11

    Here, you can check out videos and links to lots of nifty volcano stuff. Have fun! This is completely unrelated...but check it out anywho. sweet periodic table! Alaska Volcano Observatory Earthquakes and Volcanoes Check this one out for info on history\\'s most distructive volcano. Exploring Pompeii and Vesuvius Exploring the Environment: Volcanoes This will give you lots of background on how Volcanoes work, what the major parts are, and how they erupt. How Volcanoes Work A quick video on how to take a lava sample...hot! Lava Sampling on Kilauea Volcano, Hawai i A volcano in antartica? ...

  17. Man Against Volcano: The Eruption on Heimaey,

    E-print Network

    Ingólfsson, �lafur

    Man Against Volcano: The Eruption on Heimaey, Vestmannaeyjar, Iceland This booklet was originally published in 1976 under the title "Man Against Volcano:The Eruption on Heimaey, Vestmann Islands, Iceland:Town of Vestmannaeyjar with Helgafell in the right back- ground (photo courtesy of Sólarfilma). #12;Man Against Volcano

  18. A major pulse of late Eocene/early Oligocene submarine and subaerial magmatism in the central and western Aleutian arc

    NASA Astrophysics Data System (ADS)

    Jicha, B. R.; Kay, S. M.; Kay, R. W.; Tibbetts, A. K.; Singer, B. S.

    2013-12-01

    Thirty four new 40Ar/39Ar and U/Pb zircon ages from eight Central and western Aleutian Islands supplement existing geochronologic data and provide new information on the history and evolution of the early central and western Aleutian arc. A clast from a volcanic sequence in southeastern Adak in the Finger Bay Volcanic Formation, interpreted to be the oldest unit on central Aleutian Islands, yields an age of 38.19 × 0.53 Ma. The 40Ar/39Ar ages of the Finger Bay Volcanics are virtually indistinguishable from new 40Ar/39Ar and U/Pb zircon ages from the Finger Bay pluton. This age is similar to previous ages from this unit and to new 38-39 Ma lavas on Kiska and Amchitka islands. It is important to note that the Finger Bay Volcanics on Adak are not related to the initiation of the central Aleutian arc as these rocks have meteoric not sea water alteration and thus the arc must have been built above sea level when these lavas erupted. In contrast, the 39-31 Ma lavas on Kiska, Ulak, Amatignak, and Attu islands in the west central Aleutians, west of Adak have elevated 87Sr/86Sr ratios (up to 0.7045) in association with Epsilon Nd values of +7.5 to 9. We interpret this to reflect hydrothermal alteration of lavas that were submarine eruptions as the western Aleutian arc had not yet reached sea level. Northeast of Adak Island, lavas previously mapped as the Finger Bay Volcanics group on southern Great Sitkin Island range from 10.2 to 3.2 Ma in accord with northward migration of the arc front with time. A new 40Ar/39Ar age of 34.35×0.05 Ma for a granodiorite in the calc-alkaline Hidden Bay pluton on Adak is in accord with new U/Pb zircon ages in this sample, which also importantly shows no evidence of older zircons. The central Adak Gannett Lake pluton, which was assumed to have an age like the ~14 Ma Kagalaska Island pluton to the east, yields an age of 31.68 × 0.06 Ma. Thus, the new age determinations indicate that calc-alkaline plutonism lasted for more than 3 Ma on Adak Island and is part of a 38-29 Ma arc-wide period of volcanism and plutonism. The presence of continental like calc-alkaline plutons dominated by granodiorite after ~35 Ma and a lack of low-K island arc tholeiites and boninites paints a very different picture for the evolution of the central Aleutian arc than for western Pacific arcs.

  19. 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 ...

  20. Eruption of Alaska volcano breaks historic pattern

    USGS Publications Warehouse

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

    2009-01-01

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

  1. Eruption of Alaska Volcano Breaks Historic Pattern

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  2. Island of Timor, Indonesia

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This almost totally cloud free, photo of the island of Timor, Indonesia (9.0S, 125.0E) illustrates the volcanic origin of the over 1500 islands of Indonesia. Close examination of the photo reveals several eroded volcanoes on the Island of Timor and several of the adjacent islands. The linear alignment of the volcanoes, as seen from space, indicates the edges of the tectonic plates of the Earth's crust where volcanic activity is most common.

  3. Analysis of geometry of volcanoes and faults in Terceira Island (Azores): Evidence for reactivation tectonics at the EUR/AFR plate boundary in the Azores triple junction

    NASA Astrophysics Data System (ADS)

    Navarro, A.; Lourenço, N.; Chorowicz, J.; Miranda, J. M.; Catalão, J.

    2009-02-01

    The late Pliocene to Quaternary (5 Ma) volcanism in the central and eastern Azores Archipelago is related to the Eurasia/Africa divergence, but a clear deformation pattern has not yet been established at this location. This work focuses on the contribution of Synthetic Aperture Radar (SAR) scenes and Digital Elevation Models (DEM), complemented with geophysical, geodetic and morpho-structural data, to establish the geometric relationships between volcanic edifices and tectonic structures in the central and eastern Azores Archipelago. Bathymetric data were also used to extend field observations to the significant submarine area of the Azores plateau. Strikes of extension fractures, directly observed or inferred from elongated volcanic vents or linear volcanic clusters in Terceira Island, indicate that volcanism is mainly controlled by regional extension as given by NUVEL-1A plate motion model. Additionally, other directions were also detected for extension fractures around the Santa Barbara volcano (defining a radial pattern) and in the central part of the island (exhibiting an S-shape pattern). Although most of the volcanic vents are controlled by extension fractures, some seem to be controlled by faulting, such as the case of the ones rooted in releasing bends along strike-slip or oblique-slip faults in the central part of the island. Concerning the Azores plateau, most of the structures have directions that do not directly fit with present-day direction of relative motion (˜ N70°) between Eurasia and Africa. Directions ranging from N110° to N125°, found mainly along the Terceira rift, are interpreted as ancient transform directions, reactivating as transtensional fault zones due to the present-day plate motion. N-S directions are also visible in the plateau, being interpreted as former middle-oceanic rift faults reactivated as left-lateral fault zones. These results contrast with the volcanic expression in other hotspot dominated oceanic islands such as the Canaries or the Hawaii islands chain, probably due to the tectonic complexity promoted by the Azores Triple Junction instability through time.

  4. How changes in pore pressure affect fluid circulation in volcanoes: three examples from Vulcano Island, Mt. Etna and Mt Vesuvius (Italy)

    NASA Astrophysics Data System (ADS)

    Federico, C.; Madonia, P.; Capasso, G.; D'Alessandro, W.; Bellomo, S.; Brusca, L.; Cusano, P.; Longo, M.; Paonita, A.; Petrosino, S.

    2013-05-01

    Fluids circulating in volcanic edifices are attracting increasing interest from scientists, mostly because their role in triggering flank instability, phreatic explosions, and eruptions has been documented in several cases worldwide [Newhall et al. 2001, Thomas et al. 2004]. Fluid pore pressure can change as an effect of either external (meteoric recharge, variation of the stress field), or endogenous causes (e.g. internal pressurization of magmatic volatiles and hydrothermal systems). The reciprocal roles of tectonics and magmatic/hydrothermal activity are still under investigation [Gottsman et al. 2007, Roeloffs et al. 2003]. We discuss the results of decennial data records collected in the aquifers of Mt Etna, Vulcano Island and Mt Vesuvius, and get insights on the role of tectonics and volcanic activity on the observed variations of water level and chemical composition. In Vulcano Island, the shallow thermal aquifer is deeply concerned by deep volcanic fluids. The most significant variations were observed during the 1988-96 crisis, due to the large input of steam and acidic gases from depth. In addition, the record of the water table elevation provided remarkable insights on the pressure of the volcano-hydrothermal system, which can be envisaged as the cause for the onset of the phase of higher vapor output in the fumarolic field in late 2004. On Mt. Vesuvius, the geochemical behavior of the aquifer appears strictly controlled by the input of volcanic gases and variations in the stress field. These latter, which were responsible for the seismic crisis of 1999, and the almost simultaneous increased input of CO2-rich vapor, significantly affected water chemistry and temperature, until 2006. The recent observations of low salinity, temperature, and dissolved carbon contents in groundwater provide strong evidence for reduced pressure in the volcano-hydrothermal system. The record of water chemistry available on Mt. Etna since 1994 shows coeval changes in almost all monitored sites, ascribed to the variable contribution over time of waters with different temperature and composition. In addition, the dissolved CO2 content is chiefly affected by the input of volcanic CO2. Given the intense dynamics of the volcano, with frequent eruptions and periodic inflation-deflation phases, as well as the uneven deformation of the edifice, changes in water chemistry can be attributed, at least in part, to stress-related changes in pore pressure. Changes of pore pressure and micro-fracturation are controlling fluid movement (water and gases) within the volcano, producing part of the observed geochemical variations. The accurate modeling of the proposed process of fluid pressure increase, fracturing, and drainage of deep fluids will benefit of a multidisciplinary approach, able to clarify the cause-effect relationship and critical conditions. Newhall CG et al. 2001. J. Geol. Soc. Philipp., 56, 69-84. Thomas ME et al. 2004. Terra Nova, 16, 312-317. Gottsmann J. et al. 2007. GRL 34, L07307. Roeloffs E. et al. 2003. JVGR 127, 269-303.

  5. Mantle and crustal sources of carbon, nitrogen, and noble gases in Cascade-Range and Aleutian-Arc volcanic gases

    Microsoft Academic Search

    Robert B. Symonds; Robert J. Poreda; William C. Evans; Cathy J. Janik; Beatrice E. Ritchie

    ABSTRACT Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (, N) compositions of virtually air- free gas samples collected between 1994 and 1998 from 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA). Sample sites include ?173°C fumaroles and springs at Mount Shasta, Mount Hood, Mount St.

  6. Space-geodetic evidence for multiple magma reservoirs and subvolcanic lateral intrusions at Fernandina Volcano, Galápagos Islands

    NASA Astrophysics Data System (ADS)

    Bagnardi, Marco; Amelung, Falk

    2012-10-01

    Using Interferometric Synthetic Aperture Radar (InSAR) measurements of the surface deformation at Fernandina Volcano, Galápagos (Ecuador), acquired between January 2003 and September 2010, we study the structure and the dynamics of the shallow magmatic system of the volcano. Through the analysis of spatial and temporal variations of the measured line-of-sight displacement we identify multiple sources of deformation beneath the summit and the southern flank. At least two sources are considered to represent permanent zones of magma storage given their persistent or recurrent activity. Elastic deformation models indicate the presence of a flat-topped magma reservoir at ˜1.1 km below sea level and an oblate-spheroid cavity at ˜4.9 km b.s.l. The two reservoirs are hydraulically connected. This inferred structure of the shallow storage system is in agreement with previous geodetic studies and previous petrological analysis of both subaerial and submarine lavas. The almost eight-year-long observation interval provides for the first time geodetic evidence for two subvolcanic lateral intrusions from the central storage system (in December 2006 and August 2007). Subvolcanic lateral intrusions could provide the explanation for enigmatic volcanic events at Fernandina such as the rapid uplift at Punta Espinoza in 1927 and the 1968 caldera collapse without significant eruption.

  7. Investigating Geothermal Activity, Volcanic Systems, and Deep Tectonic Tremor on Akutan Island, Alaska, with Array Seismology

    NASA Astrophysics Data System (ADS)

    Haney, M. M.; Prejean, S. G.; Ghosh, A.; Power, J. A.; Thurber, C. H.

    2012-12-01

    In addition to hosting one of the most active volcanoes in the Aleutian Arc, Akutan Island, Alaska, is the site of a significant geothermal resource within Hot Springs Bay Valley (HSBV). We deployed 15 broadband (30 s to 50 Hz) seismometers in and around HSBV during July 2012 as part of an effort to establish a baseline for background seismic activity in HSBV prior to geothermal production on the island. The stations recorded data on-site and were retrieved in early September 2012. Additional targets for the array include the tracking of deep tectonic tremor known to occur within the Aleutian subduction zone and the characterization of volcano-tectonic (VT) and deep long period (DLP) earthquakes from Akutan Volcano. Because 13 of the stations in the array sit within an area roughly 1.5 km by 1.5 km, we plan to apply methods based on stacking and beamforming to analyze the waveforms of extended signals lacking clear phase arrivals (e.g., tremor). The average spacing of the seismometers, roughly 350 m, provides sensitivity to frequencies between 2-8 Hz. The stacking process also increases the signal-to-noise ratio of small amplitude signals propagating across the array (e.g., naturally occurring geothermal seismicity). As of August 2012, several episodes of tectonic tremor have been detected in the vicinity of Akutan Island during the array deployment based on recordings from nearby permanent stations operated by the Alaska Volcano Observatory (AVO). This is the first small-aperture array deployed in the Aleutian Islands and the results should serve as a guide for future array deployments along the Aleutian Arc as part of the upcoming EarthScope and GeoPRISMS push into Alaska. We demonstrate the power of array methods based on stacking at Akutan Volcano using a sequence of DLP earthquakes from June 11, 2012 that were recorded on the permanent AVO stations. We locate and characterize the lowest frequency portion of the signals at 0.5 Hz. At these low frequencies, the traditional "sparse" local network at Akutan effectively becomes a small-aperture array relative to the wavelength. We exploit the coherency among the stations and locate the DLPs by using a novel stacking method. The crux of the method involves scanning over all possible source locations and relative polarity combinations between the local stations to find the one that maximizes the stacked power at a well-defined region in the subsurface. As a result, the method is applicable even in the presence of mixed polarities. We discover that two of the stations at Akutan have DLP waveforms with opposite polarities compared to the other stations. Accounting for this polarity variation gives a DLP source location at 10 km depth, to the west-southwest of the Akutan summit caldera. These results give clear evidence for non-isotropic radiation patterns associated with DLPs and show the promise of array methods based on waveform stacking for providing future insights into the origin of volcanic as well as geothermal and tectonic seismicity.

  8. Variability of passive gas emissions, seismicity, and deformation during crater lake growth at White Island Volcano, New Zealand, 2002-2006

    USGS Publications Warehouse

    Werner, C.; Hurst, T.; Scott, B.; Sherburn, S.; Christenson, B.W.; Britten, K.; Cole-Baker, J.; Mullan, B.

    2008-01-01

    We report on 4 years of airborne measurements of CO2, SO2, and H2S emission rates during a quiescent period at White Island volcano, New Zealand, beginning in 2003. During this time a significant crater lake emerged, allowing scrubbig processes to be investigated. CO2 emissions varied from a baseline of 250 to >2000 t d-1 and demonstrated clear annual cycling that was consistent with numbers of earthquake detections and annual changes in sea level. The annual variability was found to be most likely related to increases in the strain on the volcano during sea level highs, temporarily causing fractures to reduce in size in the upper conduit. SO2 emissions varied from 0 to >400 t d-1 and were clearly affected by scrubbing processes within the first year of take development. Scrubbing caused increases of SO42- and Cl- in lake waters, and the ratio of carbon to total sulphur suggested that elemental sulphur deposition was also significant in the lake during the first year. Careful measurements of the lake level and chemistry allowed estimates of the rate of H2O(g) and HCl(g) input into the lake and suggested that the molar abundances of major gas species (H2O, CO2, SO2, and HCl) during this quiescent phase were similar to fumarolic ratios observed between earlier eruptive periods. The volume of magma estimated from CO2 emissions (0.0 15-0.04 km3) was validated by Cl- increases in the lake, suggesting that the gas and magma are transported from deep to shallow depths as a closed system and likely become open in the upper conduit region. The absence of surface deformation further leads to a necessity of magma convection to supply and remove magma from the degassing depths. Two models of convection configurations are discussed. Copyright 2008 by the American Geophysical Union.

  9. Intra-caldera Events: A Look at the Hydrovolcanic Deposit Stratigraphically Located Between two Caldera-Forming Eruptions of Okmok Volcano, Umnak Island, Alaska

    NASA Astrophysics Data System (ADS)

    Wong, L. J.

    2002-12-01

    Within the 10 km diameter caldera that characterizes Okmok Volcano, a field of post-caldera cones and deposits demonstrate many features associated with water-magma interactions. A unit deposited prior to the formation of the present caldera provides evidence for large explosive hydrovolcanic eruptions in the past as well. This unit is referred to as the Middle Scoria Unit as it is stratigraphically located between the ~9000 BP Okmok I and 2050 BP Okmok II caldera-forming events. Here, we present data on the stratigraphy, geochemistry, and eruptive mechanisms of the Middle Scoria Unit, which averages a thickness of 2.5 meters. The basal layer of the Middle Scoria consists of moderately well sorted, highly inflated juvenile clasts of basaltic composition (53.88 wt.% SiO2) that average 3 to 5 cm in size. Capping the base is a sequence of layers alternating between oxidized reddish lithic fragments and poorly vesicular scoria averaging 1 mm to 3 cm in size. The contacts between the scoria and lithic layers are less discrete in the top section, with a higher proportion of mixing averaging up to 75% for a clast-rich layer. The upper layers of the unit also show reverse grading and contain dense, poorly vesicular scoria fragments and lithic fragments of 2 mm to 1.5 cm in size. The Middle Scoria unit has been found on the neighboring Unalaska Island, approximately 30 km to the East, revealing a wide dispersal. Our results indicate that this eruption began as a highly explosive, purely magmatic and rare basaltic Plinian eruption. With time, the eruptive series evolved to incorporate external water, as demonstrated by the successions of oxidized lithic lapilli and poorly vesicular scoria layers. Our preliminary interpretations of the Middle Scoria indicate that Okmok Volcano may be capable of highly explosive basaltic Plinian and hydrovolcanic eruptions.

  10. 75 FR 8547 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-25

    ...Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands...opening and closing dates of the Atka mackerel directed fisheries within the harvest...the 2010 A season HLA limits of Atka mackerel in areas 542 and 543 of the Bering...

  11. 75 FR 792 - Fisheries of the Economic Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-06

    ...of the Economic Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian Islands AGENCY: National...SUMMARY: NMFS is opening directed fishing for Pacific cod by catcher Pacific cod by catcher/processors using hook-and-line...

  12. Mount St. Helens and Kilauea volcanoes

    SciTech Connect

    Barrat, J. (Smithsonian Institution, Washington, DC (USA))

    1989-01-01

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

  13. GPS application to the study of ground deformation in the volcano tectonic systems of the Terceira Island (Azores) - preliminary results

    Microsoft Academic Search

    Rita Rodrigues; Teresa Ferreira; Jun Okada; António Trota; João. Gaspar

    2010-01-01

    The Azores Archipelago comprises nine volcanic islands, located where the Eurasian, American and African plates meet. Due to this complex tectonic setting seismic and volcanic activities are frequent in the archipelago. Since its settlement, in the 15th century, several volcanic eruptions and destructive earthquakes have been reported causing thousands of deaths and severe damages. Last eruption in the Azores occurred

  14. Seismic Activity Around and Under Krakatau Volcano, Sunda Arc: Constraints to the Source Region of Island Arc Volcanics

    Microsoft Academic Search

    A. Špi?ák; V. Hanuš; J. Van?k

    2002-01-01

    There is general agreement that calc-alkaline volcanic rocks at convergent plate margins are genetically related to the process of subduction (Ringwood, 1974; Maaloe and Petersen, 1981; Hawkesworth et al., 1997). However, opinions on the mode and site of generation of primary magma for island arc volcanism differ substantially. The site of generation of calc-alkaline magma is thought to be either

  15. Don Swanson at Ash Outcrop Near Volcano Observatory

    USGS Multimedia Gallery

    Don Swanson (USGS Hawaiian Volcano Observatory) shows scientists in the CSAV International class how layers of ash outside of HVO indicate past explosive eruptions of Kilauea. Hawaiian Volcano Observatory, Hawaii Island, Hawaii...

  16. Volcano Live

    NSDL National Science Digital Library

    The volocanologist John Seach provides the latest volcano news and information on volcanoes all across the world. The website provides fun hands-on activities, tutorials in volcano safety and volcanology, and a glossary. Students can discover the geography of many areas of the world and how it impacts the likelihood of volcanic eruptions. Users can find links to numerous volcano cameras and maps. The amazing images of volcanoes from Seach's expeditions are a great addition to this informative site.

  17. The EarthScope Plate Boundary Observatory Akutan Alaskan Volcano Tiltmeter Installation

    NASA Astrophysics Data System (ADS)

    Pauk, B. A.; Gallaher, W.; Dittmann, T.; Smith, S.

    2007-12-01

    During August of 2007, the Plate Boundary Observatory (PBO) successfully installed four Applied Geomechanics Lily Self Leveling Borehole Tiltmeters on Akutan Volcano, in the central Aleutian islands of Alaska. All four stations were collocated with existing PBO Global Positioning Systems (GPS) stations installed on the volcano in 2005. The tiltmeters will aid researchers in detecting and measuring flank deformation associated with future magmatic intrusions of the volcano. All four of the tiltmeters were installed by PBO field crews with helicopter support provided by JL Aviation and logistical support from the Trident Seafood Corporation, the City of Akutan, and the Akutan Corporation. Lack of roads and drivable trails on the remote volcanic island required that all drilling equipment be transported to each site from the village of Akutan by slinging gear beneath the helicopter and with internal loads. Each tiltmeter hole was drilled to a depth of approximately 30 feet with a portable hydraulic/pneumatic drill rig. The hole was then cased with splined 2.75 inch PVC. The PVC casing was cemented in place with grout and the tiltmeters were installed and packed with fine grain sand to stabilize the tiltmeters inside the casing. The existing PBO NetRS GPS receivers were configured to collect the tiltmeter data through a spare receiver serial port at one sample per minute and 1 hour files. Data from the GPS receivers and tiltmeters is telemetered directly or through a repeater radio to a base station located in the village of Akutan that transmits the data using satellite based communications to connect to the internet and to the UNAVCO Facility data archive where it is made freely available to the public.

  18. Detection of microwave emission due to rock fracture as a new tool for geophysics: A field test at a volcano in Miyake Island, Japan

    NASA Astrophysics Data System (ADS)

    Takano, Tadashi; Maeda, Takashi; Miki, Yoji; Akatsuka, Sayo; Hattori, Katsumi; Nishihashi, Masahide; Kaida, Daishi; Hirano, Takuya

    2013-07-01

    This paper describes a field test to verify a newly discovered phenomenon of microwave emission due to rock fracture in a volcano. The field test was carried out on Miyake Island, 150 km south of Tokyo. The main objective of the test was to investigate the applicability of the phenomenon to the study of geophysics, volcanology, and seismology by extending observations of this phenomenological occurrence from the laboratory to the natural field. We installed measuring systems for 300 MHz, 2 GHz, and 18 GHz-bands on the mountain top and mountain foot in order to discriminate local events from regional and global events. The systems include deliberate data subsystems that store slowly sampled data in the long term, and fast sampled data when triggered. We successfully obtained data from January to February 2008. During this period, characteristic microwave pulses were intermittently detected at 300 MHz. Two photographs taken before and after this period revealed that a considerably large-scale collapse occurred on the crater cliff. Moreover, seismograms obtained by nearby observatories strongly suggest that the crater subsidence occurred simultaneously with microwave signals on the same day during the observation period. For confirmation of the microwave emission caused by rock fracture, these microwave signals must be clearly discriminated from noise, interferences, and other disturbances. We carefully discriminated the microwave data taken at the mountaintop and foot, checked the lightning strike data around the island, and consequently concluded that these microwave signals could not be attributed to lightning. Artificial interferences were discriminated by the nature of their waveforms. Thus, we inferred that the signals detected at 300 MHz were due to rock fractures during cliff collapses. This result may provide a useful new tool for geoscientists and for the mitigation of natural hazards.

  19. 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-based instruments are supplemented by remote sensing data sets. UNAVCO supports the acquisition of InSAR and LiDAR imaging data, with archiving and distribution of these data provided by UNAVCO and partner institutions. We provide descriptions and access information for geodetic data from the PBO volcano subnetworks and their applications to monitoring for scientific and public safety objectives. We also present notable examples of activity recorded by these instruments, including the 2004-2010 accelerated uplift episode at the Yellowstone caldera and the 2006 Augustine eruption.

  20. Repeating coupled earthquakes at Shishaldin Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Caplan-Auerbach, Jacqueline; Petersen, Tanja

    2005-07-01

    Since it last erupted in 1999, Shishaldin Volcano, Aleutian Islands, Alaska, has produced hundreds to thousands of long-period (1-2 Hz; LP) earthquakes every day with no other sign of volcanic unrest. In 2002, the earthquakes also exhibited a short-period (4-7 Hz; SP) signal occurring between 3 and 15 s before the LP phase. Although the SP phase contains higher frequencies than the LP phase, its spectral content is still well below that expected of brittle failure events. The SP phase was never observed without the LP phase, although LP events continued to occur in the absence of the precursory signal. The two-phased events are termed "coupled events", reflecting a triggered relationship between two discrete event types. Both phases are highly repetitive in time series, suggestive of stable, non-destructive sources. Waveform cross-correlation and spectral coherence are used to extract waveforms from the continuous record and determine precise P-wave arrivals for the SP phase. Although depths are poorly constrained, the SP phase is believed to lie at shallow (<4 km) depths just west of Shishaldin's summit. The variable timing between the SP and LP arrivals indicates that the trigger mechanism between the phases itself moves at variable speeds. A model is proposed in which the SP phase results from fluid moving within the conduit, possibly around an obstruction and the LP phase results from the coalescence of a shallow gas bubble. The variable timing is attributed to changes in gas content within the conduit. The destruction of the conduit obstacle on November 21, 2002 resulted in the abrupt disappearance of the SP phase.

  1. Repeating coupled earthquakes at Shishaldin Volcano, Alaska

    USGS Publications Warehouse

    Caplan-Auerbach, J.; Petersen, T.

    2005-01-01

    Since it last erupted in 1999, Shishaldin Volcano, Aleutian Islands, Alaska, has produced hundreds to thousands of long-period (1-2 Hz; LP) earthquakes every day with no other sign of volcanic unrest. In 2002, the earthquakes also exhibited a short-period (4-7 Hz; SP) signal occurring between 3 and 15 s before the LP phase. Although the SP phase contains higher frequencies than the LP phase, its spectral content is still well below that expected of brittle failure events. The SP phase was never observed without the LP phase, although LP events continued to occur in the absence of the precursory signal. The two-phased events are termed "coupled events", reflecting a triggered relationship between two discrete event types. Both phases are highly repetitive in time series, suggestive of stable, non-destructive sources. Waveform cross-correlation and spectral coherence are used to extract waveforms from the continuous record and determine precise P-wave arrivals for the SP phase. Although depths are poorly constrained, the SP phase is believed to lie at shallow (<4 km) depths just west of Shishaldin's summit. The variable timing between the SP and LP arrivals indicates that the trigger mechanism between the phases itself moves at variable speeds. A model is proposed in which the SP phase results from fluid moving within the conduit, possibly around an obstruction and the LP phase results from the coalescence of a shallow gas bubble. The variable timing is attributed to changes in gas content within the conduit. The destruction of the conduit obstacle on November 21, 2002 resulted in the abrupt disappearance of the SP phase.

  2. The implementation of a volcano seismic monitoring network in Sete Cidades Volcano, São Miguel, Açores

    Microsoft Academic Search

    N. Wallenstein; A. Montalvo; U. Barata; R. Ortiz

    2003-01-01

    Sete Cidades is one of the three active central volcanoes of S. Miguel Island, in the Azores archipelago. With a 5 kilometres wide caldera, it has the highest eruptive record in the last 5000 years with 17 intracaldera explosive events (Queiroz, 1997). Only submarine volcanic eruptions occurred in Sete Cidades volcano-tectonic system since the settlement of the island, in the

  3. Precursory characteristics of the seismicity before the 6 August 2012 eruption of Tongariro volcano, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Hurst, Tony; Jolly, Arthur D.; Sherburn, Steven

    2014-10-01

    The 6 August 2012 eruption from the Upper Te Maari crater of Tongariro volcano followed approximately three weeks of precursory seismic activity. Earthquake relocations including data from extra temporary stations indicated that nearly all events were in a small area very close to Upper Te Maari. Most of these relocated events were very shallow, with nearly all events being between 1000 and 1500 m below the ground surface. The pre-eruption seismicity occurred in three main swarms. During the first swarm on 12-13 July 2012, all the earthquakes had consistent inter-event times of 71 ± 8 min, while in the later swarms (17-20 and 29-30 July) many events had a similar pattern of consistent inter-event times. The stationary quasi-periodic ("clockwork") earthquake process suggests that a single fracture point was excited by a nearly constant rate flux process. The dominant type of earthquake observed in these swarms had a sharp onset and a broad spectrum, with strong energy from 2 to 10 Hz. Most events seen had a local magnitude of 1.5 to 2.5, with virtually no smaller events. Most of these earthquakes appeared to belong to a main earthquake family whose characteristics included a strong spectral component at about 2 Hz and three bursts of energy spaced at intervals of about 1.5 s. Of the 116 located earthquakes, 75 had a correlation coefficient greater than 0.70 with a master event. The spectra of these events did not change with size, with matching frequency peaks for all the events with a high correlation. The last event of this type was the day before the 6 August 2012 eruption, none have been seen since and there has been very little seismicity under Tongariro. This seismicity alerted GNS Science and other organisations to the unrest of Tongariro, and the Volcanic Alert Level and Aviation Colour Code were raised to publicise this. GNS Science also increased its monitoring of Tongariro, and discovered that the magmatic gas concentrations had increased compared to previous measurements in May 2012. However, the seismicity did not show any accelerating trend that suggested an immediate eruption threat, indicating the difficulty of predicting small eruptions in Tongariro and similar volcanoes.

  4. Petrology of the 2008 eruption of Kasatochi volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Izbekov, P. E.

    2008-12-01

    Kasatochi volcano, a 3 × 3 km island in the Andreanof Islands group in the central Aleutians, erupted explosively with little warning on August 7, 2008. For two days the eruption sent ash clouds to an altitude of nearly 45000 ft asl. Within two weeks, immediately after the activity at Kasatochi decreased, the island was visited by AVO scientist Chris Waythomas, who was able to collect a suite of samples from pyroclastic flow deposits formed during the climatic phase of the eruption. Pumiceous juvenile blocks appear to be one of the predominant lithologies in the pyroclastic flows. The whole rock composition of magmas erupted during the climatic phase shows little variation, e.g. 58.46 - 59.19 wt. % SiO2, 6.98 - 7.09 wt. % CaO, and 1.00 - 1.07 wt.% K2O. The erupted andesite is crystalline-rich, with phenocryst content of nearly 40 vol. %. The mineral assemblage includes plagioclase, ortho- and clinopyroxenes, hornblende, and Ti-magnetite. The matrix glass is clear, compositionally uniform (68.5± 0.8 wt.% SiO2) and contains elongated microlites of plagioclase, pyroxenes, and amphibole. Most mineral phases appear to be chemically and texturally homogeneous with little or no signs of disequilibrium. Hornblende phenocrysts have no reaction rims that form in response to syn-eruptive ascent and decompression of magmas. Ongoing petrological investigations will use compositions of mineral and glass phases in the erupted products to constrain pre- and syn-eruptive magma conditions during the 2008 Kasatochi event.

  5. A tectonic earthquake sequence preceding the April-May 1999 eruption of Shishaldin Volcano, Alaska

    USGS Publications Warehouse

    Moran, S.C.; Stihler, S.D.; Power, J.A.

    2002-01-01

    On 4 March 1999, a shallow ML 5.2 earthquake occurred beneath Unimak Island in the Aleutian Arc. This earthquake was located 10-15 km west of Shishaldin Volcano, a large, frequently active basaltic-andesite stratovolcano. A Strombolian eruption began at Shishaldin roughly 1 month after the mainshock, culminating in a large explosive eruption on 19 April. We address the question of whether or not the eruption caused the mainshock by computing the Coulomb stress change caused by an inflating dike on fault planes oriented parallel to the mainshock focal mechanism. We found Coulomb stress increases of ???0.1 MPa in the region of the mainshock, suggesting that magma intrusion prior to the eruption could have caused the mainshock. Satellite and seismic data indicate that magma was moving upwards beneath Shishaldin well before the mainshock. indicating that, in an overall sense, the mainshock cannot be said to have caused the eruption. However, observations of changes at the volcano following the mainshock and several large aftershocks suggest that the earthquakes may, in turn, have influenced the course of the eruption.

  6. Causation or coincidence? The correlations in time and space of the 2008 eruptions of Cleveland, Kasatochi, and Okmok Volcanoes, Alaska

    NASA Astrophysics Data System (ADS)

    Cervelli, P. F.; Cameron, C. E.

    2008-12-01

    In mid-summer 2008, three significant volcanic eruptions occurred in the Andreanof Islands of the Aleutian Arc, Alaska. Okmok volcano began erupting on July 12, followed by Cleveland on July 21, and then by Kasatochi on August 7. In addition to this temporal correlation, there is also a geographic correlation: the eruptions occurred in a 525 km region representing only about 20% of the arc's length. Given these close proximities in space and time, it is natural to speculate about whether an underlying process is at work. Ultimately, the arc exists because of subduction, but the question remains if a more immediate trigger may be responsible for the concurrence. We began our inquiry into whether a link exists among the three eruptions by posing the following question: What is the probability that, by chance alone, Okmok, Kasatochi and Cleveland could simultaneously erupt? Answering this question requires both a statistical model for eruption frequency and empirical data of where and when eruptions have occurred in the past. We assume that eruptions follow a Poisson distribution, and estimate the expected number of eruptions per time interval for each volcano in the arc from the geologic record and observations contained in the Alaska Volcano Observatory's GeoDIVA database. We then perform a Monte Carlo experiment, simulating 10,000 years of eruptive activity at 30 day intervals. The results of the simulation indicate that the phenomenon of three eruptions beginning in a single month happens about once every 90 years. A spatial constraint requiring that the maximum separation among the volcanoes be less than 525 km increases this interval to about once every 900 years. Though these intervals are not so long as to rule out coincidence, they are long enough to warrant further investigation into the possibility of a common origin. Several candidates for a prospective cause are: (1) the Great Aleutian Earthquake of 1957, which includes the region of the three recent eruptions, may have triggered a period of increased volcanic activity that still persists; (2) a slow slip event, with associated non- volcanic tremor, have may have resulted in static stress changes favorable to volcanic eruptions; or (3) nearby volcanoes may interact with one another in such a way as to increase the chance of clustered eruptions. We consider each of these scenarios (as well as other more remote possibilities) and weigh their relative likelihoods against the probability of random correlation. In the end, no definitive answer emerges, though pure coincidence remains a simple and plausible explanation for this remarkable event.

  7. Groundwater salinity and hydrochemical processes in the volcano-sedimentary aquifer of La Aldea, Gran Canaria, Canary Islands, Spain.

    PubMed

    Cruz-Fuentes, Tatiana; Cabrera, María del Carmen; Heredia, Javier; Custodio, Emilio

    2014-06-15

    The origin of the groundwater salinity and hydrochemical conditions of a 44km(2) volcano-sedimentary aquifer in the semi-arid to arid La Aldea Valley (western Gran Canaria, Spain) has been studied, using major physical and chemical components. Current aquifer recharge is mainly the result of irrigation return flows and secondarily that of rainfall infiltration. Graphical, multivariate statistical and modeling tools have been applied in order to improve the hydrogeological conceptual model and identify the natural and anthropogenic factors controlling groundwater salinity. Groundwater ranges from Na-Cl-HCO3 type for moderate salinity water to Na-Mg-Cl-SO4 type for high salinity water. This is mainly the result of atmospheric airborne salt deposition; silicate weathering, and recharge incorporating irrigation return flows. High evapotranspiration produces significant evapo-concentration leading to relative high groundwater salinity in the area. Under average conditions, about 70% of the water used for intensive agricultural exploitation in the valley comes from three low salinity water runoff storage reservoirs upstream, out of the area, while the remaining 30% derives from groundwater. The main alluvial aquifer behaves as a short turnover time reservoir that adds to the surface waters to complement irrigation water supply in dry periods, when it reaches 70% of irrigation water requirements. The high seasonality and intra-annual variability of water demand for irrigation press on decision making on aquifer use by a large number of aquifer users acting on their own. PMID:24698802

  8. 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. PMID:25627249

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  10. Craniometric variation in the Aleutians: integrating morphological, molecular, spatial, and temporal data.

    PubMed

    Ousley, Stephen D; Jones, Erica B

    2010-12-01

    Several hypotheses have been put forward about the origins and evolution of the inhabitants of the Aleutian Islands. Both Hrdli?ka [The Aleutian and Commander Islands and Their Inhabitants (Philadelphia: Wistar Institute of Anatomy and Biology, 1945)] and Laughlin ["The Alaska gateway viewed from the Aleutian Islands," in Papers on the Physical Anthropology of the American Indian, W. S. Laughlin, ed. (New York: Viking Fund, 1951), 98-126] analyzed cranial morphology and came to somewhat different conclusions using a typological approach and limited analytical methods. Subsequent investigations using morphological data have not significantly improved our understanding of Aleut prehistory. More recently, radiocarbon dating and mitochondrial DNA analyses have shed light on Aleut genetic variation and changes over time, but better morphological methods using multivariate statistical analysis have not yet been used. We analyzed craniometric data using multivariate procedures and found that Aleuts demonstrate significant changes in cranial morphology over time, and these changes correspond to Hrdli?ka's observations but may not necessarily reflect in-migration. The morphological changes were concentrated in the very aspects of morphology that are easily observable and that Hrdli?ka most often measured, namely, cranial length, breadth, and height, but they were obscured when craniometric variation as a whole was analyzed. Also, we found that the morphological changes over time were not related to the changes in haplogroup frequencies over time, suggesting that migration into the Aleutians did not play a significant role in producing the morphological changes. However, craniometric variability apparently increases over time, suggesting in-migration, localized selection, and/or greater environmental heterogeneity. Our results contradict Laughlin's observations but may be more in line with his hypothesis of in situ evolutionary changes absent gene flow. In addition to selection, gene flow, and gene drift, however, sociocultural changes must also be considered as a factor in why morphology changed over time. PMID:21417887

  11. Evidence of flank failure deposit reactivation in a shield volcano. A favorable context for deep-seated landslide activation (La Réunion Island)

    NASA Astrophysics Data System (ADS)

    Belle, Pierre; Aunay, Bertrand; Famin, Vincent; Join, Jean-Lambert

    2014-05-01

    Giant flank failures are recurrent features of shield volcanoes, and their deposits (i.e. breccia), constitute a significant volume in a volcanic edifice. On La Réunion Island, the growth and development of Piton des Neiges volcano has been punctuated by several flank failure episodes. One of these failures is a deep-seated landslide (>200 Mm3) occurring nowadays in Grand Ilet, a plateau inhabited by 1 000 people in the cirque of Salazie, on the northern flank of Piton des Neiges. Here we present the results of a multidisciplinary study (structural geology and field mapping, GNSS monitoring, borehole logging) performed to characterize the geological structure the Grand Ilet landslide, and identify the instability factors that control this category of destabilization. Basic breccia deposits, up to 160 meters thick, constitute the main geological formation of the unstable mass. This breccia are cut by the headwall scar of the landslide, and covered by lava flows, indicating a minimum age of 200 kyr for the destabilization that produced the deposits. The breccia is consolidated out of the landslide area. The NE toe of the landslide is evidenced by an important compressional deformation of the base of the breccia, and striated surfaces in this deformed volume indicate a NE-direction of transport. In this deformed bulge, a clay-rich layer at the base of the breccia has been identified as the main slip plane. Using a video inspection of drill casings on three exploration boreholes, we reconstructed the 3D geometry of the slip plane at the base of the breccia. This reconstruction shows that the landslide plane has an average dip of 6° toward the NE. The displacement monitoring network shows that the unstable mass has a 5.5 km2 extension, with a variable azimuth of movement direction (N140° for the SW sector, and N45° for the NE sector). The planimetric displacements velocities range between 2 cm/year in the inner part of the unstable mass to 52 cm/year at the landslide toe. The dip of displacement vectors vary from 34° ± 9 uphill to 7° ± 2 downhill near the landslide toe. This displacement field, the topography and the drill casings inspection show that secondary shear zones are located inside the landslide mass, characterized by a lower deformation rate than the basal shear zone. However heterogeneous is the deformation, it more important at the base of the breccia (locally in the clay layer). Ultimately, our study suggests that the main slip plane has localized at the base of the breccia despite its induration. Thus we conclude that the Grand Ilet landslide is in fact a present-day reactivation of an old destabilization.

  12. Fumarole-Supported Islands of Biodiversity within a Hyperarid, High-Elevation Landscape on Socompa Volcano, Puna de Atacama, Andes? †

    PubMed Central

    Costello, Elizabeth K.; Halloy, Stephan R. P.; Reed, Sasha C.; Sowell, Preston; Schmidt, Steven K.

    2009-01-01

    Fumarolic activity supports the growth of mat-like photoautotrophic communities near the summit (at 6,051 m) of Socompa Volcano in the arid core of the Andes mountains. These communities are isolated within a barren, high-elevation landscape where sparse vascular plants extend to only 4,600 m. Here, we combine biogeochemical and molecular-phylogenetic approaches to characterize the bacterial and eucaryotic assemblages associated with fumarolic and nonfumarolic grounds on Socompa. Small-subunit rRNA genes were PCR amplified, cloned, and sequenced from two fumarolic soil samples and two reference soil samples, including the volcanic debris that covers most of the mountain. The nonfumarolic, dry, volcanic soil was similar in nutrient status to the most extreme Antarctic Dry Valley or Atacama Desert soils, hosted relatively limited microbial communities dominated by Actinobacteria and Fungi, and contained no photoautotrophs. In contrast, modest fumarolic inputs were associated with elevated soil moisture and nutrient levels, the presence of chlorophyll a, and 13C-rich soil organic carbon. Moreover, this soil hosted diverse photoautotroph-dominated assemblages that contained novel lineages and exhibited structure and composition comparable to those of a wetland near the base of Socompa (3,661-m elevation). Fumarole-associated eucaryotes were particularly diverse, with an abundance of green algal lineages and a novel clade of microarthropods. Our data suggest that volcanic degassing of water and 13C-rich CO2 sustains fumarole-associated primary producers, leading to a complex microbial ecosystem within this otherwise barren landscape. Finally, we found that human activities have likely impacted the fumarolic soils and that fumarole-supported photoautotrophic communities may be exceptionally sensitive to anthropogenic disturbance. PMID:19074608

  13. Savage Earth: Out of the Inferno - Volcanoes

    NSDL National Science Digital Library

    This article, entitled Mountains of Fire, describes the relationship between the types of volcanic activity and plate movement and the connection between types of volcanoes and how they erupt. The article is supported by a video of an erupting volcano, a photograph of an eruption and an animation depicting pyroclastic flow and the formation of a composite volcano. It is also supported by three sidebars, called Volcanoes of North America, Montserrat: An Island Under Siege, and Volcanoes on other Planets. These sidebars also have videos or photographs to enhance their message.

  14. 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 ...

  15. Cascades Volcano Observatory - Learn About Volcanoes: Frequently Asked Volcano Questions

    NSDL National Science Digital Library

    This page provides the answers to frequently asked questions about volcanoes. It is created by the United States Geological Survey. Topics addressed include: What Is A Volcano? Why Do Volcanoes Occur? How Do Volcanoes Erupt? Where Do Volcanoes Occur? When Will A Volcano Erupt? How Hot Is A Volcano? Can Lava Be Diverted? Do Volcanoes Affect Weather? What Types of Volcanoes are There? Which Eruptions Were The Deadliest? 20th Century Volcanic Eruptions and Their Impact. About 60 additional questions with answers are available under MORE FAQ's -Volcano Questions and Answers, and includes some sections on volcanoes of the western United States. Other links to volcano information are also available.

  16. Geology and 40Ar/39Ar geochronology of the medium- to high-K Tanaga volcanic cluster, western Aleutians

    USGS Publications Warehouse

    Jicha, Brian R.; Coombs, Michelle L.; Calvert, Andrew T.; Singer, Brad S.

    2012-01-01

    We used geologic mapping and geochemical data augmented by 40Ar/39Ar dating to establish an eruptive chronology for the Tanaga volcanic cluster in the western Aleutian arc. The Tanaga volcanic cluster is unique in comparison to other central and western Aleutian volcanoes in that it consists of three closely spaced, active, volumetrically significant edifices (Sajaka, Tanaga, and Takawangha), the eruptive products of which have unusually high K2O contents. Thirty-five new 40Ar/39Ar ages obtained in two different laboratories constrain the duration of Pleistocene–Holocene subaerial volcanism to younger than 295 ka. The eruptive activity has been mostly continuous for the last 150 k.y., unlike most other well-characterized arc volcanoes, which tend to grow in discrete pulses. More than half of the analyzed Tanaga volcanic cluster lavas are basalts that have erupted throughout the lifetime of the cluster, although a considerable amount of basaltic andesite and basaltic trachyandesite has also been produced since 200 ka. Major- and trace-element variations suggest that magmas from Sajaka and Tanaga volcanoes are likely to have crystallized pyroxene and/or amphibole at greater depths than the older Takawangha magmas, which experienced a larger percentage of plagioclase-dominated fractionation at shallower depths. Magma output from Takawangha has declined over the last 86 k.y. At ca. 19 ka, the focus of magma flux shifted to the west beneath Tanaga and Sajaka volcanoes, where hotter, more mafic magma erupted.

  17. Sharing Resources for Aleutian Arc Research

    NASA Astrophysics Data System (ADS)

    Jicha, Brian; Yogodzinski, Gene; Kelemen, Peter

    2014-03-01

    The Aleutian arc is arguably the best place on Earth to investigate several fundamental questions about arc magmatism and subduction initiation because the record of arc growth is mostly preserved due to a lack of intra-arc rifting. In December, 94 scientists met in San Francisco, Calif., at a workshop sponsored by the Geodynamic Processes at Rifting and Subduction Margins (GeoPRISMS) program to discuss possibilities for sharing resources for fieldwork in the Aleutian arc so that the cost per project could be reduced.

  18. Decade Volcanoes

    NSDL National Science Digital Library

    In the 1990s, the International Association of Volcanology and Chemistry of the Earth's Interior started the Decade Volcano Project. As part of their work, they designated sixteen volcanoes particularly worthy of study "because of their explosive histories and close proximity to human populations." The group recently teamed up with National Geographic to create a guide to these volcanoes via this interactive map. Navigating through the map, visitors can learn about Mount Rainier, Colima, Galeras, Santorini, and other prominent volcanoes. For each volcano, there's a brief sketch that gives the date of its last eruption, its elevation, nearby population centers, and a photograph.

  19. Plant Diversity Changes during the Postglacial in East Asia: Insights from Forest Refugia on Halla Volcano, Jeju Island

    PubMed Central

    Dolezal, Jiri; Altman, Jan; Kopecky, Martin; Cerny, Tomas; Janecek, Stepan; Bartos, Michael; Petrik, Petr; Srutek, Miroslav; Leps, Jan; Song, Jong-Suk

    2012-01-01

    Understanding how past climate changes affected biodiversity is a key issue in contemporary ecology and conservation biology. These diversity changes are, however, difficult to reconstruct from paleoecological sources alone, because macrofossil and pollen records do not provide complete information about species assemblages. Ecologists therefore use information from modern analogues of past communities in order to get a better understanding of past diversity changes. Here we compare plant diversity, species traits and environment between late-glacial Abies, early-Holocene Quercus, and mid-Holocene warm-temperate Carpinus forest refugia on Jeju Island, Korea in order to provide insights into postglacial changes associated with their replacement. Based on detailed study of relict communities, we propose that the late-glacial open-canopy conifer forests in southern part of Korean Peninsula were rich in vascular plants, in particular of heliophilous herbs, whose dramatic decline was caused by the early Holocene invasion of dwarf bamboo into the understory of Quercus forests, followed by mid-Holocene expansion of strongly shading trees such as maple and hornbeam. This diversity loss was partly compensated in the Carpinus forests by an increase in shade-tolerant evergreen trees, shrubs and lianas. However, the pool of these species is much smaller than that of light-demanding herbs, and hence the total species richness is lower, both locally and in the whole area of the Carpinus and Quercus forests. The strongly shading tree species dominating in the hornbeam forests have higher leaf tissue N and P concentrations and smaller leaf dry matter content, which enhances litter decomposition and nutrient cycling and in turn favored the selection of highly competitive species in the shrub layer. This further reduced available light and caused almost complete disappearance of understory herbs, including dwarf bamboo. PMID:22438890

  20. How Are Islands Formed?

    NSDL National Science Digital Library

    2001-01-01

    This lesson provides students with information about how islands are formed, including a basic knowledge of plate tectonics. Using the islands of Hawaii as an example, students learn about the earth processes that cause the formation of islands over time, including volcanoes and hot spots.

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

    ERIC Educational Resources Information Center

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

    2000-01-01

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

  2. Volcano watch Monitoring risk on Auckland's volcanic field

    E-print Network

    Auckland, University of

    Volcano watch Monitoring risk on Auckland's volcanic field Lest we forget Our Memory Lab@auckland.ac.nz Volcano watchThe recent eruptions at Mt Tongariro and White Island are a timely reminder for Auckland (pictured with Lucy McGee, who has recently completed her doctorate) is dating the city's 50 volcanoes

  3. Strain Accumulation and Strain Partitioning in the Western Aleutian Subduction Zone

    NASA Astrophysics Data System (ADS)

    Steblov, G. M.; Kogan, M. G.

    2005-12-01

    The 2,200-km Aleutian megathrust demonstrates a rapid change in the sense of relative motion of the Pacific and North American plates, from nearly trench normal at Alaska to nearly trench parallel at Kamchatka, where the Aleutian and Kamchatka megathrusts connect making a cusp. This change is accompanied by an increase in the relative plate velocity from 61 to 76 mm/yr (an estimate based on our global GPS solution). Earthquake slip vector azimuths for thrust earthquakes along the arc support an idea of strain partitioning, i.e., the motion in seismic ruptures tends to be less oblique than the plate motion [MacCaffrey, 1992]. The strain partitioning predicts a steady westward motion of slivers of the hanging wall along strike-slip faults, resulting in an active collision of the far western arc with Kamchatka [Geist and Scholl, 1994]. GPS velocities measured on Aleutian islands progressively increase from 12 mm/yr at the eastern end of the arc (Kodiak) to as much as 49 mm/yr at the western end (Bering) with respect to the North American plate, which is 2/3 of the relative plate velocity. We show, using the constrained nonlinear inversion, that the high GPS velocity of Bering Is. can be alternatively explained by elastic strain accumulation resulting from locking at the subduction interface. In this scenario, there is no steady westward drift of arc slivers since the elastic strain is periodically released in earthquakes, with the islands returning to their original positions. Geodetic observations lasting for about a decade (continuous GPS was installed on Bering Is. in 1996) do not allow us to discriminate the periodic elastic strain accumulation from the along arc steady strike-slip motion. Yet there is a good argument in favor of the elastic strain at the interface beneath Bering Is.: small GPS velocities in Kamchatka at the Aleutian-Kamchatka cusp (<14 mm/yr) are easily explained by superposed elastic strains at Kamchatka and Aleutian subduction interfaces. There is simply no evidence in GPS velocities of intense compression near Cape Kamchatka as predicted by the collision scenario. Moreover, specific azimuths and values of GPS velocities in Kamchatka at the cusp can be easily explained by superposed elastic strains. Some amount of slivering in the westernmost Aleutians is clearly evidenced by abundant strike-slip seismic focal mechanisms, yet the rate of motion along fracture zones to the north and to the south of the arc currently is unknown; it can be small with respect to the elastic strain accumulation in an azimuth parallel to the arc. Unless longer time series at larger number of islands are observed, a unique interpretation of GPS velocities on the Aleutians is not possible. Recently, the first epoch of GPS at Medny (Copper) Is. was carried out, in 100 km from Bering and at greater distance from the Aleutian Trench. Comparison of GPS velocities at Bering and Medny should provide evidence on how significant is the strain partitioning. Bürgmann, R., M.G. Kogan, G.M. Steblov, G. Hilley, V.E. Levin, and T. Apel, Interseismic Coupling and Asperity Distribution Along the Kamchatka Subduction Zone, J. Geophys. Res., 110, B07405, doi:10.1029/2005JB003648, 2005.

  4. Soil microbial structure and function post-volcanic eruption on Kasatochi Island and regional controls on microbial heterogeneity

    NASA Astrophysics Data System (ADS)

    Zeglin, L. H.; Rainey, F.; Wang, B.; Waythomas, C.; Talbot, S. L.

    2013-12-01

    Microorganisms are abundant and diverse in soil and their integrated activity drives nutrient cycling on the ecosystem scale. Organic matter (OM) inputs from plant production support microbial heterotrophic life, and soil geochemistry constrains microbial activity and diversity. As vegetation and soil develops over time, these factors change, modifying the controls on microbial heterogeneity. Following a volcanic eruption, ash deposition creates new surfaces where both organismal growth and weathering processes are effectively reset. The trajectory of microbial community development following this disturbance depends on both organic matter accumulation and geochemical constraints. Also, dispersal of microbial cells to the sterile ash surface may determine microbial community succession. The Aleutian Islands (Alaska, USA) are a dynamic volcanic region, with active and dormant volcanoes distributed across the volcanic arc. One of these volcanoes, Kasatochi, erupted violently in August 2008, burying a small lush island in pryoclastic flows and fine ash. Since, plants and birds are beginning to re-establish on developing surfaces, including legacy soils exposed by rapid erosion of pyroclastic deposits, suggesting that recovery of microbial life is also proceeding. However, soil microbial diversity and function has not been examined on Kasatochi Island or across the greater Aleutian region. The project goal is to address these questions: How is soil microbial community structure and function developing following the Kasatochi eruption? What is the relative importance of dispersal, soil OM and geochemistry to microbial community heterogeneity across the Aleutians? Surface mineral soil (20-cm depth) samples were collected from Kasatochi Island in summer 2013, five years after the 2008 eruption, and from eight additional Aleutian islands. On Kasatochi, pryoclastic deposits, exposed legacy soils supporting regrowth of remnant dune wild-rye (Leymus mollis) and mesic meadow plant communities, and soils impacted by recovering seabird rookeries were sampled. On the other islands, soils supporting both Leymus and mesic meadow communities (representative of dominant vegetation types on Kasatochi pre-eruption) were sampled. For each soil category and island combination, three transects of soil cores at 10-cm, 50-cm, 1-m, 5-m and 10-m distance were collected; with distances between sites and islands included (up to >700 km), the range of geographic distance examined covers over 7 orders of magnitude. For all samples, data on fundamental geochemical and OM factors, bacterial and fungal biomass, activity and diversity (via QPCR, extracellular enzyme potential assays and T-RFLP) are being collected. Covariance analysis is being used to evaluate the scale of maximum spatial heterogeneity in microbial structure and function, and ordination and matrix correlation analyses are being used to identify the key environmental covariates with heterogeneity. We hypothesize that heterogeneity at small (cm) scales will reflect predominant geochemical controls, at medium (m) scales will reflect predominant OM (vegetation) controls and at large (km) scales will reflect dispersal-related controls on microbial community structure and function.

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

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Z.; 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.

  6. Erupting Volcanoes!

    NSDL National Science Digital Library

    This lesson presents volcanoes through the making of volcano models. While students are constructing their physical representations of volcanoes, they will be filled with questions about volcanoes as well as how to build their models. This process will provide students with a tangible reference for learning about volcanoes and give them a chance to problem-solve as they build their models. Students will be able to observe how the eruption changes the original form of their volcano model. In this way, students see first hand how this type of phenomenon creates physical change. While students at this level may struggle to understand larger and more abstract geographical concepts, they will work directly with material that will help them build a foundation for understanding concepts of phenomena that sculpt the Earth.

  7. Eruptions of Taal Volcano 1976-1977

    Microsoft Academic Search

    John A. Wolfe

    1980-01-01

    Sixty kilometers due south of Manila, Philippines, hidden behind an ignimbrite delta, which at its rim is nearly 700-m high, is the active Taal Volcano. There is a lake of 267 km2 in the volcano-tectonic depression and within it an island of 25 km2. The island has been constructed largely by phreatomagmatic activity, added to in historic times. The last

  8. Deadly Volcanos

    NSDL National Science Digital Library

    This interactive slide show provides accounts of eight of history's most deadly volcanic eruptions. These eruptions are from both ancient and modern times, and include such volcanos as Mount Vesuvius, Tambora, Krakatau, Nevado del Ruiz, and Mount Pinatubo. Each slide features an illustration from the event, a written description with the name of the volcano, date, number of casualties, an account of the eruption, and a map showing the location of the volcano.

  9. Geodetic Measurements and Numerical Modeling of the Deformation Cycle for Okmok Volcano, Alaska: 1993-2008

    NASA Astrophysics Data System (ADS)

    Ohlendorf, S. J.; Feigl, K.; Thurber, C. H.; Lu, Z.; Masterlark, T.

    2011-12-01

    Okmok Volcano is an active caldera located on Umnak Island in the Aleutian Island arc. Okmok, having recently erupted in 1997 and 2008, is well suited for multidisciplinary studies of magma migration and storage because it hosts a good seismic network and has been the subject of synthetic aperture radar (SAR) images that span the recent eruption cycle. Interferometric SAR can characterize surface deformation in space and time, while data from the seismic network provides important information about the interior processes and structure of the volcano. We conduct a complete time series analysis of deformation of Okmok with images collected by the ERS and Envisat satellites on more than 100 distinct epochs between 1993 and 2008. We look for changes in inter-eruption inflation rates, which may indicate inelastic rheologic effects. For the time series analysis, we analyze the gradient of phase directly, without unwrapping, using the General Inversion of Phase Technique (GIPhT) [Feigl and Thurber, 2009]. This approach accounts for orbital and atmospheric effects and provides realistic estimates of the uncertainties of the model parameters. We consider several models for the source, including the prolate spheroid model and the Mogi model, to explain the observed deformation. Using a medium that is a homogeneous half space, we estimate the source depth to be centered at about 4 km below sea level, consistent with the findings of Masterlark et al. [2010]. As in several other geodetic studies, we find the source to be approximately centered beneath the caldera. To account for rheologic complexity, we next apply the Finite Element Method to simulate a pressurized cavity embedded in a medium with material properties derived from body wave seismic tomography. This approach allows us to address the problem of unreasonably large pressure values implied by a Mogi source with a radius of about 1 km by experimenting with larger sources. We also compare the time dependence of the source to published results that used GPS data.

  10. Strain Accommodation Along an Oblique Subduction Zone: Integrating Paleomagnetic Data and Stress Patterns in the Central Aleutian Forearc

    NASA Astrophysics Data System (ADS)

    Krutikov, L.; Reynolds, J. R.; Stone, D. B.

    2005-12-01

    Present day motion of the Pacific plate relative to the North American plate shifts along the Aleutian arc from normal convergence in the east to transform motion in the west. Oblique subduction, partitioned into an arc-normal component and an arc-parallel component, creates a spatially complex pattern of deformation in the overriding plate. Strain partitioning results in tectonic segmentation of the forearc region, caused by increasing obliquity of plate convergence and apparently characterized by clockwise rotation and westward translation of discrete blocks in the central and western Aleutian arc [e.g., Geist et al., Tectonics 7, 327-341, 1988]. Archived cores collected from islands in the central Aleutian arc for previous paleomagnetic studies are being remeasured and reanalyzed using modern thermal demagnetization techniques that were not available at the time of collection. These new measurements indicate counterclockwise rotation or less significant clockwise rotations than those predicted by the block rotation model. Paleomagnetic results are presented for Tertiary and Quaternary volcanic rocks from Adak and Amchitka Islands in the central Aleutians. Results range from no statistically significant rotation in young intrusives, to a number of paleomagnetic vectors in the Finger Bay volcanics (~55 Ma) that suggest clockwise rotation since the time of original magnetization. Paleomagnetic results are combined with analyses of seafloor lineations in high-resolution multibeam sonar data collected in 2003 and 2004 of representative sites between 173W and 179E along the central Aleutian arc. Major fault lineations and joint patterns observed in the bathymetry data are analyzed to estimate the direction of maximum horizontal stress. Lineations in rocks of different stratigraphic ages and paleomagnetic results are being compared with 0-5Ma regional stress patterns [Scholl et al., 1989] to constrain the style and timing of deformation.

  11. Constraints on the composition of the Aleutian arc lower crust from VP/VS

    NASA Astrophysics Data System (ADS)

    Shillington, Donna J.; van Avendonk, Harm J. A.; Behn, Mark D.; Kelemen, Peter B.; Jagoutz, Oliver

    2013-06-01

    Determining the bulk composition of island arc lower crust is essential for distinguishing between competing models for arc magmatism and assessing the stability of arc lower crust. We present new constraints on the composition of high P-wave velocity (VP = 7.3-7.6 km/s) lower crust of the Aleutian arc from best-fitting average lower crustal VP/VS ratio using sparse converted S-waves from an along-arc refraction profile. We find a low VP/VS of ~1.7-1.75. Using petrologic modeling, we show that no single composition is likely to explain the combination of high VP and low VP/VS. Our preferred explanation is a combination of clinopyroxenite (~50-70%) and alpha-quartz bearing gabbros (~30-50%). This is consistent with Aleutian xenoliths and lower crustal rocks in obducted arcs, and implies that ~30-40% of the full Aleutian crust comprises ultramafic cumulates. These results also suggest that small amounts of quartz can exert a strong influence on VP/VS in arc crust.

  12. Syn and posteruptive hazards of maar–diatreme volcanoes

    Microsoft Academic Search

    Volker Lorenz

    2007-01-01

    Maar–diatreme volcanoes represent the second most common volcano type on continents and islands. This study presents a first review of syn- and posteruptive volcanic and related hazards and intends to stimulate future research in this field. Maar–diatreme volcanoes are phreatomagmatic monogenetic volcanoes. They may erupt explosively for days to 15 years. Above the preeruptive surface a relatively flat tephra ring forms.

  13. Volcano Landslides

    NSDL National Science Digital Library

    Information given in this United States Geological Survey (USGS) publication includes a description of volcano landslides, how they are generated, and their effects on surrounding areas. Case studies of specific volcano landslides are linked from this page, including Mt. St. Helens, Otake in Japan, Huila in Columbia, Mt. Rainier, and Casita in Nicaragua.

  14. Redoubt Volcano

    USGS Multimedia Gallery

    Ascending eruption cloud from Redoubt Volcano as viewed to the west from the Kenai Peninsula. The mushroom-shaped plume rose from avalanches of hot debris (pyroclastic flows) that cascaded down the north flank of the volcano. A smaller, white steam plume rises from the summit crater. ...

  15. Assessment of metals in down feathers of female common eiders and their eggs from the Aleutians: arsenic, cadmium, chromium, lead, manganese, mercury, and selenium

    Microsoft Academic Search

    Joanna Burger; Michael Gochfeld; Christian Jeitner; Daniel Snigaroff; Ronald Snigaroff; Timothy Stamm; Conrad Volz

    2008-01-01

    Concentrations of arsenic, cadmium, chromium, lead, manganese, mercury and selenium were examined in the down feathers and\\u000a eggs of female common eiders (Somateria mollissima) from Amchitka and Kiska Islands in the Aleutian Chain of Alaska to determine whether there were (1) differences between\\u000a levels in feathers and eggs, (2) differences between the two islands, (3) positive correlations between metal levels

  16. Evolutionary Consequences of Recently Founded Aleut Communities in the Commander and Pribilof Islands

    E-print Network

    Rubicz, Rohina C.

    2007-09-24

    ). Recent archaeological investigations in the eastern islands have stressed cultural continuity in the Aleutians. Excavations at the Margaret Bay site, near Unalaska Island, appear to bridge the gap between Anangula and later sites. The ‘transitional... culture’ of Margaret Bay contains both blades, which are characteristic of the earliest Aleutian sites, and the bifaces that are present in later assemblages (Knecht and Davis 2001). Margaret Bay is a large site, with abundant archaeological features...

  17. Volcano spacing and plate rigidity

    SciTech Connect

    Brink, U. (Stanford Univ., California (USA))

    1991-04-01

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

  18. Large landslides from oceanic volcanoes

    Microsoft Academic Search

    Robin T. Holcomb; Roger C. Searle

    1991-01-01

    GLORIA sidescan sonar surveys have shown that 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. Large

  19. Model Volcanoes

    NSDL National Science Digital Library

    In this lesson, students will explore volcanoes by constructing models and reflect upon their learning through drawing sketches of their models. Once they have finished making their models, they will experiment with making their volcanoes erupt. They will observe how eruption changes the original form of their volcano models. In this way, students see first hand how this type of phenomena creates physical change. While students at this level may struggle to understand larger and more abstract geographical concepts, they will work directly with material that will help them build a foundation for understanding concepts of phenomena that sculpt the earth.

  20. Volcano Instability Induced by Resurgence at the Ischia Island Caldera (Italy), and the Tsunamigenic Potential of the Related Debris Avalanche Deposits: a Complex Source of Hazard at Land-sea Interface

    NASA Astrophysics Data System (ADS)

    Tinti, S.; Zaniboni, F.; Pagnoni, G.; Marotta, E.; Della Seta, M.; de Vita, S.; Orsi, G.; Sansivero, F.; Fredi, P.

    2009-05-01

    Slope instability is a common feature in the evolution of active volcanic areas. The occurrence of mass movements is doubly linked to volcanism and volcano-tectonism, which act as either preparing factor (through increased topographic gradients or emplacement of unconsolidated deposits on slopes) or triggering factor (through earthquakes and/or eruptions). Debris avalanches and lahars in active volcanic areas are an additional factor of hazard, due to their high destructive power. Moreover, volcanoes located in coastal areas or on islands, may experience lateral collapses with the potential to generate large tsunamis. Ischia is an active volcanic island in the Gulf of Naples. Volcanism begun prior to 150 ka and continued, with periods of quiescence, until the last eruption in 1302 A.D. It has been dominated by a caldera-forming eruption (55 ka), which was followed by resurgence of the caldera floor. Volcanism and gravitational mass movements have been coeval to resurgence, which generated a maximum net uplift of about 900 m over the past 33 ka. Resurgence occurred through intermittent uplifting and tectonic quietness phases. During uplift, volcanism and generation of mass movements were very active. The resurgent area is composed of differentially displaced blocks and has a poligonal shape, resulting from reactivation of regional faults and activation of faults directly related to volcano-tectonism. The western sector is bordered by inward-dipping, high-angle reverse faults, cut by late outward-dipping normal faults due to gravitational readjustment of the slopes. The north-eastern and the south-western sides are bordered by vertical faults with right transtensive and left transpressive movements, respectively. The area located to the east of the most uplifted block is displaced by outward- dipping normal faults. Some giant landslides and their relationships with volcano-tectonism have been recognized at Ischia. Their deposits are intercalated with primary volcanics and minor landslide deposits in the eastern sector of the island. Within the northern and western sectors, historical earthquake-triggered landslides are well exposed, also due to lack of recent volcanic rocks. The largest landslide bodies seem to have a submarine counterpart, as evidenced by the hummocky topography of the seafloor in the offshore of the island. The recognized landslides vary from small lahars to large debris-avalanche, whose detachment areas are clearly conditioned by the geometry of the same structures that drove resurgence and fed volcanism. Tsunami hazard in the Gulf of Naples has not yet evaluated, even though potential for tsunami generation exists due to the recognized cases of slope failure. The catastrophic collapse that formed the big scar in the southern flank of Ischia can be taken as the upper limit case for tsunamigenic failures on the island, although smaller episodes have also to be taken into account. Ischia subaerial slopes are known to be prone to failures: although usually subaerial landslides do not reach the sea, the case of a tsunamigenic subaerial failure cannot be ruled out. Further the existence of a lot of scars along the submarine flanks of the edifice, evidences several past events and scenarios of possible future landslides.

  1. The Slab Portal Beneath the Western Aleutians Vadim Levin1*

    E-print Network

    Levin, Vadim

    The Slab Portal Beneath the Western Aleutians Vadim Levin1* , Nikolai M. Shapiro2 , Jeffrey Park3 a portal in the otherwise continuous lithospheric slab. The portal is likely to facilitate the production of the slab. The Miocene age of adakites above the westernmost Aleutians may indicate that the portal

  2. Evolution of elastic properties and acoustic emission, during uniaxial loading of rocks, from the Fogo Volcano in the island of Sao Miguel, Azores; Preliminary results.

    NASA Astrophysics Data System (ADS)

    Moreira, M.; Wallenstein, N.

    2012-04-01

    A Computerized Uniaxial Press working up to 250 kN was installed in the middle 2011 in the Laboratory of Microseismic Monitoring of ISEL. The system is able to record continuous time, pressure and axial strain (1 µm resolution) at 1s sampling rate. The loading platens were designed to integrate acoustic emission (AE) transducers. Signals are acquired and processed through an 8-channel ESG Hyperion Ultrasonic Monitoring System (10 MSPS, 14/16-bit ADC). The first experiments, presented here, were applied to a set of rock samples from the Fogo, an active central volcano in the island of Sao Miguel. Two different volcanic rock types were studied: a fine grained alkali basaltic rock with a porphyritic texture, a porosity of 4.5% and bulk density of 2700 kg m-3 (sample #3); and a benmoreitic rock with a trachytic texture, a porosity of 8.1 %, and bulk density of 2400 kg m-3 (sample #4). Cores from sample #3 were subjected to continuous increasing pressure, until failure. They show a uniaxial compressive strength (UCS) spanning from 60 to 85 MPa and a stress-strain curve with two phases: a first one with relative low Young's Module (YM) followed by a second phase were the YM increases roughly 3 times. The stress transition value occurs broadly in a stress level 50% of the UCS. The AE produced in the process is almost negligible until the YM transition stress level and increases after that. Important pulses of high AE rate occur, (> 100 s-1), associated with the occurrence and propagation of fractures, which are always parallel to the principal stress, showing an evident pattern of tensile fractures. About 20s before the failure, very important deformation rate is observed, the YM strongly decrease, and continuous AE events, with low rate, usually <50 s-1. The failure is accompanied with a sudden rise of AE events with rate > 200 s-1. Cycling stress experiences were also performed showing reversible stress-strain relation for axial pressure below the YM transition level, and important hysteresis for axial pressure above that level. The associated AE events show a characteristic Kaiser effect pattern. Cores from sample #4 undergo the same continuous increasing stress process, but failure is attained at a considerable lower pressure of 20-25 MPa. The stress-strain curves show an almost linear relation, but approaching the stress level of failure, the YM decreases. The AE events are constant but with a reduced rate until the decrease of the YM, when a significant rise in the AE occurs, achieving emission rates greater that 200 s-1. The fracture shows a characteristic shear pattern. Differences in stress-strain behavior, fracture mode and AE rates are associated with the very different structure of the rocks, once the basaltic sample is very fine grained with some very scattered and almost spherical vesicles or voids, while the benmoreitic core shows high values of porosity in a structure with vesicles and voids with very irregular shapes. Work supported by FCT, Portugal, projet FreeRock, PTDC/CTE-GIX/100687/2008

  3. Wildfowl & Wetlands Trust Wildfowl (2011) 61: 329 Recovery of the Aleutian Cackling Goose

    E-print Network

    Black, Jeff

    2011-01-01

    are especially important. The Aleutian Cackling Goose Branta hutchinsii leucopareia (formerly the Aleutian Canada3 ©Wildfowl & Wetlands Trust Wildfowl (2011) 61: 3­29 Recovery of the Aleutian Cackling Goose Cackling Goose, endangered species, habitat, hazing, hunting, recovery. #12;4 Aleutian Goose 10-year review

  4. Atmospheric distribution and removal of volcanic ash after the eruption of Kasatochi volcano: A regional model study

    NASA Astrophysics Data System (ADS)

    Langmann, Baerbel; ZakšEk, Klemen; Hort, Matthias

    2010-01-01

    In August 2008, Kasatochi volcano on the Aleutian Islands erupted without much advance warning. Volcanic ash released during this eruption quickly settled out of the atmosphere, mainly into the NE Pacific Ocean. The amount of volcanic ash, as well as the ash fall area and volume into the NE Pacific Ocean, remains speculative, as only a limited number of measurements is available. We used a three-dimensional atmosphere/chemistry-aerosol model to determine the atmospheric distribution of SO2 and volcanic ash and its fallout after the eruption of Kasatochi volcano. In a first step, modeled atmospheric SO2 distributions are compared with satellite data, thereby evaluating the model capabilities to reasonably reproduce atmospheric transport patterns. For modeled volcanic ash mass a considerable reduction of the atmospheric content already occurred by 10 August, the second day after the eruption in accordance with satellite observations. Gravitational settling is the most efficient removal process for volcanic ash mass, exceeding dry and wet deposition by far. Assuming an ash volume of 0.3 km3 released during the eruption of Kasatochi volcano and a median ash particle diameter of 4 ?m, the mass of volcanic ash removed at ground within the 0.1 mm isopach covers an area of 7.6 × 105 km2 over the NE Pacific Ocean and makes up 49% of the removed material out of the atmosphere. The amount of ash and that of iron attached to it is sufficient to explain measured seawater CO2 decrease at the ocean station Papa in August 2008 induced by iron fertilization and subsequent phytoplankton production.

  5. Cascade Volcanoes

    USGS Multimedia Gallery

    The volcanoes from closest to farthest are Mt. Washington, Three Fingered Jack, Mt. Jefferson. This picture is taken from Middle Sister looking north in the Cascade Range, Three Sisters Wilderness Area, Deschutes National Forest, Oregon....

  6. Volcano Preparedness

    MedlinePLUS

    ... your local emergency officials. Mudflows Mudflows are powerful “rivers” of mud that can move 20 to 40 ... cannot see the volcano during an eruption. Avoid river valleys and low lying areas. Trying to watch ...

  7. Volcano Hazards Program Webcams

    MedlinePLUS

    Volcano Hazards Program Webcams Below is a list of webcams of U.S. volcanoes. All webcams are operated ... the webcam. Pu`u `O`o vent, Kilauea Volcano (HVO) Halema`uma`u from HVO, Kilauea Volcano ( ...

  8. Oxygen isotope constraints on the petrogenesis of Aleutian arc magmas

    SciTech Connect

    Singer, B.S.; O'Neil, J.R. (Univ. of Michigan, Ann Arbor (United States)); Brophy, J.G. (Indiana Univ., Bloomington (United States))

    1992-04-01

    The first measurement of {sup 18}O/{sup 16}O ratios of plagioclase, clinopyroxene, orthopyroxene, and titanomagnetite phenocrysts from modern Aleutian island-arc lavas provides new insight and independent constraints on magma sources and intracrustal processes. Basalts are heterogeneous on the scale of the entire arc and individual volcanic centers. Combined with Sr isotope and trace element data {delta}{sup 18}O{sub plag} values suggest a variable magma source characterized by differences in the mantle wedge or the subducted sediment component along the volcanic front. Seven tholeiitic basalt to rhyodacite lavas from the Seguam volcanic center have nearly identical {delta}{sup 18}O{sub plag} values of 6.0{per thousand} {plus minus} 0.2{per thousand}, reflecting extensive closed-system plagioclase-dominated crystal fractionation. Oxygen isotope thermometry and pyroxene and oxide equilibria indicate that differentiation occurred between 1,150 {plus minus} 100C (basalt) and 950 {plus minus} 100C (rhyodacite). In contrast, {delta}{sup 18}O{sub plag} values of 12 calc-alkalic basaltic andesites and andesites from the smaller Kanaga volcanic center span a broader range of 5.9{per thousand}-6.6{per thousand}, and consist of mostly higher values. Isotopic disequilibrium in the Kanaga system is manifest in two ways: two types of basaltic inclusions with contrasting {delta}{sup 18}O values occur in one andesite, and in two other andesites plagioclase-titanomagnetite and clinopyroxene-titanomagnetite oxygen isotope temperatures are inconsistent.

  9. Mass Wasting in the Western Galapagos Islands

    E-print Network

    Hall, Hillary

    2012-10-19

    Oceanic island volcanoes such as those in the Hawaiian, Canary and Galapagos Islands are known to become unstable, causing failures of the subaerial and submarine slopes of the volcanic edifices. These mass wasting events appear to be the primary...

  10. Mahukona: The missing Hawaiian volcano

    SciTech Connect

    Garcia, M.O.; Muenow, D.W. (Univ. of Hawaii, Honolulu (USA)); Kurz, M.D. (Woods Hole Oceanographic Institution, MA (USA))

    1990-11-01

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

  11. Seismic-hazard maps for Alaska and the Aleutian Islands

    USGS Publications Warehouse

    Wesson, Robert L.; Frankel, Arthur D.; Mueller, Charles S.; Harmsen, Stephen C.

    1999-01-01

    Probabilistic seismic hazard maps were prepared for Alaska portraying peak horizontal ground acceleration and horizontal spectral response acceleration for 0.2, 0.3, and 1.0 second periods with probabilities of exceedance of 10% in 50 years and 2% in 50 years. This particular data set is for horizontal spectral response acceleration for 1.0 second period with a 10% probability of exceedance in 50 years. All of the maps were prepared by combining hazard derived from spatially- smoothed historic seismicity with hazard from fault-specific sources. The acceleration values contoured are the random horizontal component. The reference site condition is firm rock, defined as having an average shear-wave velocity of 760 m/sec in the top 30 meters corresponding to the boundary between NEHRP site classes B and C. This data set represents the results of calculations of hazard curves for a grid of points with a spacing of 0.1 degrees in latitude and longitude. The grid of points were contoured to produce the final representation of the seismic-hazard.

  12. Three New Speciesof Heteroderoidea (Nematoda)from the Aleutian Islands

    E-print Network

    Bernard, Ernest

    - lauds galled roots of a dunegrass, Elymus mollis Trin., which were found to contain females, then proc- essed to glycerin by a rapid method (5). Measurements were made on specimens mounted in glycerin 31 January 1981. 'Associate Professor, Department of Entomology and Plant Pathology, University

  13. Surface deformation analysis of the Mauna Loa and Kilauea volcanoes, Hawaii , revealed by InSAR measurements

    Microsoft Academic Search

    F. Casu; M. Poland; G. Solaro; P. Tizzani; A. Miklius; E. Sansosti; R. Lanari

    2009-01-01

    The Big Island of Hawaii is home to three volcanoes that have historically erupted. Hualalai, on the east side of the island, Mauna Loa, the largest volcano on the planet which has erupted 39 times since 1832 (most recently in 1984) and Kilauea, which has been in a state of continuous eruption since 1983 from vents on the volcano's east

  14. Cascade Range Volcanoes: North to South

    NSDL National Science Digital Library

    This page lists Cascades Range volcanoes of British Columbia, Washington State, Oregon, and California. The user can click on the volcano name to get information on the volcano and its vicinity including Current Activity; Background and Information; Current Hazards Report; Visit a Volcano; Maps, Graphics, and Images; Items of Interest; and Useful Links. The volcanoes include: Garibaldi Lake Volcano, Meager Mountain, and Mount Garibaldi in British Columbia; Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State: Mount Hood, Mount Jefferson, Three-Fingered Jack, Mount Washington, Belknap Shield Volcano, Three Sisters (North, Middle, South), Broken Top, Mount Bachelor, Pilot Butte, Lava Butte, Newberry Caldera, Diamond Peak, Mount Bailey, Mount Thielsen, Crater Lake, Mount Mazama, Wizard Island, and Mount McLoughlin in Oregon:, and Lava Beds, Medicine Lake Volcano, Glass Mountain (Medicine Lake, California), Black Butte, Mount Shasta, and Lassen Peak in California. Links are provided to more general pages on volcanoes in the three states and in Canada.

  15. Sustained long-period seismicity at Shishaldin Volcano, Alaska

    USGS Publications Warehouse

    Petersen, T.; Caplan-Auerbach, J.; McNutt, S.R.

    2006-01-01

    From September 1999 through April 2004, Shishaldin Volcano, Aleutian Islands, Alaska, exhibited a continuous and extremely high level of background seismicity. This activity consisted of many hundreds to thousands of long-period (LP; 1-2 Hz) earthquakes per day, recorded by a 6-station monitoring network around Shishaldin. The LP events originate beneath the summit at shallow depths (0-3 km). Volcano tectonic events and tremor have rarely been observed in the summit region. Such a high rate of LP events with no eruption suggests that a steady state process has been occurring ever since Shishaldin last erupted in April-May 1999. Following the eruption, the only other signs of volcanic unrest have been occasional weak thermal anomalies and an omnipresent puffing volcanic plume. The LP waveforms are nearly identical for time spans of days to months, but vary over longer time scales. The observations imply that the spatially close source processes are repeating, stable and non-destructive. Event sizes vary, but the rate of occurrence remains roughly constant. The events range from magnitude ???0.1 to 1.8, with most events having magnitudes <1.0. The observations suggest that the conduit system is open and capable of releasing a large amount of energy, approximately equivalent to at least one magnitude 1.8-2.6 earthquake per day. The rate of observed puffs (1 per minute) in the steam plume is similar to the typical seismic rates, suggesting that the LP events are directly related to degassing processes. However, the source mechanism, capable of producing one LP event about every 0.5-5 min, is still poorly understood. Shishaldin's seismicity is unusual in its sustained high rate of LP events without accompanying eruptive activity. Every indication is that the high rate of seismicity will continue without reflecting a hazardous state. Sealing of the conduit and/or change in gas flux, however, would be expected to change Shishaldin's behavior. ?? 2005 Elsevier B.V. All rights reserved.

  16. Volcano Baseball

    NSDL National Science Digital Library

    American Association for the Advancement of Science

    2009-01-01

    In this game, learners are volcanoes that must complete several steps to erupt. Starting at home plate, learners draw cards until they have enough points to move to first base. This process repeats for each learner at each base, and each base demonstrates a different process in a volcano's eruption. The first learner to make it back to home plate erupts and is the winner. This is a good introduction to volcanoes. When learners set up a free account at Kinetic City, they can answer bonus questions at the end of the activity as a quick assessment. As a larger assessment, learners can complete the Smart Attack game after they've completed several activities.

  17. 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.

  18. Indirect food web interactions: Sea otters and kelp forest fishes in the Aleutian archipelago

    USGS Publications Warehouse

    Reisewitz, S.E.; Estes, J.A.; Simenstad, C.A.

    2006-01-01

    Although trophic cascades - the effect of apex predators on progressively lower trophic level species through top-down forcing - have been demonstrated in diverse ecosystems, the broader potential influences of trophic cascades on other species and ecosystem processes are not well studied. We used the overexploitation, recovery and subsequent collapse of sea otter (Enhydra lutris) populations in the Aleutian archipelago to explore if and how the abundance and diet of kelp forest fishes are influenced by a trophic cascade linking sea otters with sea urchins and fleshy macroalgae. We measured the abundance of sea urchins (biomass density), kelp (numerical density) and fish (Catch per unit effort) at four islands in the mid-1980s (when otters were abundant at two of the islands and rare at the two others) and in 2000 (after otters had become rare at all four islands). Our fish studies focused on rock greenling (Hexagrammos lagocephalus), the numerically dominant species in this region. In the mid-1980s, the two islands with high-density otter populations supported dense kelp forests, relatively few urchins, and abundant rock greenling whereas the opposite pattern (abundant urchins, sparse kelp forests, and relatively few rock greenling) occurred at islands where otters were rare. In the 2000, the abundances of urchins, kelp and greenling were grossly unchanged at islands where otters were initially rare but had shifted to the characteristic pattern of otter-free systems at islands where otters were initially abundant. Significant changes in greenling diet occurred between the mid-1980s and the 2000 although the reasons for these changes were difficult to assess because of strong island-specific effects. Whereas urchin-dominated communities supported more diverse fish assemblages than kelp-dominated communities, this was not a simple effect of the otter-induced trophic cascade because all islands supported more diverse fish assemblages in 2000 than in the mid-1980s. ?? Springer-Verlag 2005.

  19. Volcano Seismology

    Microsoft Academic Search

    BERNARD CHOUET

    2003-01-01

    -- A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with

  20. Klyuchevskaya Volcano

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Klyuchevskaya Volcano on Russia's Kamchatka Peninsula continued its ongoing activity by releasing another plume on May 24, 2007. The same day, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image, at 01:00 UTC. In this image, a hotspot marks the volcano's summit. Outlined in red, the hotspot indicates where MODIS detected unusually warm surface temperatures. Blowing southward from the summit is the plume, which casts its shadow on the clouds below. Near the summit, the plume appears gray, and it lightens toward the south. With an altitude of 4,835 meters (15,863 feet), Klyuchevskaya (sometimes spelled Klyuchevskoy or Kliuchevskoi) is both the highest and most active volcano on the Kamchatka Peninsula. As part of the Pacific 'Ring of Fire,' the peninsula experiences regular seismic activity as the Pacific Plate slides below other tectonic plates in the Earth's crust. Klyuchevskaya is estimated to have experienced more than 100 flank eruptions in the past 3,000 years. Since its formation 6,000 years ago, the volcano has seen few periods of inactivity. NASA image courtesy the MODIS Rapid Response Team at NASA GSFC. The Rapid Response Team provides daily images of this region.

  1. Infrared science of Hawaiian volcanoes

    USGS Publications Warehouse

    Fischer, William A.; Moxham, R.M.; Polcyn, R.C.; Landis, G.H.

    1964-01-01

    Aerial infrared-sensor surveys of Kilauea volcano have depicted the areal extent and the relative intensity of abnormal thermal features in the caldera area of the volcano and along its associated rift zones. Many of these anomalies show correlation with visible steaming and reflect convective transfer of heat to the surface from subterranean sources. Structural details of the volcano, some not evident from surface observation, are also delineated by their thermal abnormalities. Several changes were observed in the patterns of infrared emission during the period of study; two such changes show correlation in location with subsequent eruptions, but the cause-and-effect relationship is uncertain. Thermal anomalies were also observed on the southwest flank of Mauna Loa; images of other volcanoes on the island of Hawaii, and of Haleakala on the island of Maui, revealed no thermal abnormalities. Approximately 25 large springs is- suing into the ocean around the periphery of Hawaii have been detected. Infrared emission varies widely with surface texture and composition, suggesting that similar observations may have value for estimating surface conditions on the moon or planets.

  2. Radiocarbon dates for lava flows from northeast rift zone of Mauna Loa Volcano, Hilo 7 1/2 minute quadrangle, Island of Hawaii

    USGS Publications Warehouse

    Buchanan-Banks, J. M.; Lockwood, J.P.; Rubin, M.

    1989-01-01

    Twenty-eight 14C analyses are reported for carbonized roots and other plant material collected from beneath 15 prehistoric lava flows erupted from the northeast rift zone (NERZ) of Mauna Loa Volcano (ML). The new 14C dates establish ages for 13 previously undated lava flows, and correct or add to information previously reported. Limiting ages on other flows that lie either above or below the dated flows are also established. These dates help to unravel the eruptive history of ML's NERZ. -from Authors

  3. A Direct Comparison of MODIS and COSPEC Sulfur Dioxide Measurements of the May 21, 2003 Eruption Plume of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Meier, V. L.; Scuderi, L.; Fischer, T.; Hilton, D.

    2007-05-01

    Quantifying the SO2 burden emitted from a volcano is critical to understanding a volcano's current state of activity. Ground-based instruments such as the correlation spectrometer (COSPEC) and the mini-DOAS are most routinely employed to measure volcanic SO2. Both instruments are human operated so they must be deployed on-site to obtain SO2 estimates. This makes it difficult and costly to regularly monitor active volcanoes world- wide. Satellite-based measurements, which can provide SO2 estimates in near real-time, have increasingly been used as a tool for volcanic monitoring. The Moderate Resolution Imaging Spectrometer (MODIS) located on board the Terra and Aqua satellites provides twice daily coverage of the Earth and has the capacity to detect volcanic SO2. The ability of MODIS to accurately detect and quantify SO2 in volcanic plumes using a SO2 retrieval program, MAP_SO2, was compared with COSPEC on the May 21, 2003 plume at Anatahan volcano (16.35oN, 145.67oE). MODIS was able to clearly detect SO2 in the plume and the MAP_SO2 derived SO2 flux was calculated (independently from the COSPEC data) to be more than twice the COSPEC derived flux (10,270 t/d and 3,000 - 4,500 t/d respectively). However, calculating a flux introduces additional errors. Therefore another means of comparing the two methods is utilized: a direct comparison of plume cross-sections from these two different methods. The MODIS image used with the MAP_SO2 program was acquired at 13:25 local time. The COSPEC traverse began at 13:35 local time and ended 14:40 local time. The time of the MODIS image acquisition and the start of the COSPEC traverse occurred within 10 minutes of each other. Although the MODIS image is a snap shot in time and the COSPEC traverse took about an hour to complete, the timing is so close that these two products are ideal for the comparison. The differences in these observations are used to better quantify SO2 emissions, to assess the current mismatch between ground-based and remotely sensed retrievals, and to aid in the development of an approach to continuously and accurately monitor volcanic activity from space in near real-time.

  4. Seismic Cycle at the Alaska-Aleutian Subduction Zone

    Microsoft Academic Search

    J. T. Freymueller

    2008-01-01

    Over the last century the Alaska-Aleutian subduction zone has generated an M8+ earthquake about once every 15 years, and it has generated three of the ten largest earthquakes in instrumental history. But the Alaska-Aleutian subduction zone does not display uniform properties along strike. Instead, the shallow plate interface features several distinct segments; individual segments generally have either a very wide

  5. Mt. Erebus: A Surprising Volcano: Grades K-1: Illustrated Book

    NSDL National Science Digital Library

    Jessica Fries-Gaither

    This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. Students read about the volcano in a simplified manner. The text is written at a kindergarten through grade one reading level. This version is a full-color PDF that can be printed, cut and folded to form a book. Each book contains color photographs and illustrations.

  6. Michigan Tech Volcanoes

    NSDL National Science Digital Library

    The Michigan Tech Volcanoes Page encourages collaborative, interdisciplinary work on active volcanos, and links to resources for the Santa Maria Decade Volcano in Guatemala and for Central America's most frequently active volcano, Fuego. Also includes images of Pinatubo Volcano [one nice one taken from the Space Shuttle Endeavor] and some movies of laharic activity.

  7. Cascades Volcano Observatory

    NSDL National Science Digital Library

    The Cascades Volcano Observatory of the U.S. Geological Survey has announced a WWW server offering information on volcanically-induced geologic and hydrologic hazards as well as images of volcanoes and volcanic phenomena. Includes links to ther components of the USGS Volcano Hazards Program such as the Alaska and Hawaii Volcano Observatory and the international Volcano Disaster Assistance Program.

  8. Violent explosions yield new insights into dynamics of Stromboli volcano

    Microsoft Academic Search

    A. Bertagnini; M. Coltelli; P. Landi; M. Pompilio; M. Rosi

    1999-01-01

    Crystal-poor magma may be a chief factor in the steadiness of activity at the Stromboli volcano in Italy. This was one of the findings to emerge from the documentation of a number of violent explosions there last year. The findings are giving scientists new insights into the dynamics of the volcano.Stromboli, on an island of the same name in the

  9. Eruptions of Hawaiian Volcanoes: Past, Present, and Future

    NSDL National Science Digital Library

    Robert Tilling

    The origin of the Hawaiian Islands, recorded eruptions, and eruption patterns are discussed in this United States Geological Survey (USGS) publication. The on-line book also covers volcano monitoring and research, landforms and structures, hazards and benefits, and a discussion of Loihi, Hawaii's newest volcano.

  10. Space-geodetic evidence for multiple magma reservoirs and subvolcanic lateral intrusions at Fernandina Volcano,

    E-print Network

    Amelung, Falk

    at Fernandina Volcano, Galápagos Islands Marco Bagnardi1 and Falk Amelung1 Received 23 May 2012; revised 12 Aperture Radar (InSAR) measurements of the surface deformation at Fernandina Volcano, Galápagos (Ecuador magmatic system of the volcano. Through the analysis of spatial and temporal variations of the measured

  11. Newberry Volcano--Central Oregon's Sleeping Giant U.S. Department of the Interior

    E-print Network

    Torgersen, Christian

    Newberry Volcano--Central Oregon's Sleeping Giant U.S. Department of the Interior U.S. Geological Survey USGS Fact Sheet 2011-3145 2011 the largest volcano in the Cascades volcanic arc and covers an area the size of Rhode Island. Unlike familiar cone-shaped Cascades volcanoes, Newberry was built into the shape

  12. Monitoring Erebus volcano's active lava lake; tools, techniques and observations

    E-print Network

    Peters, Nial John

    2015-03-03

    Active lava lakes present a rare opportunity to observe directly the complex processes occurring within a magma body. Situated on Ross Island, Antarctica, the 3794-m-high crater of Erebus volcano has hosted a phonolite lava lake for decades...

  13. Orographic Flow over an Active Volcano

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  14. Mid-Pleistocene lavas from the Seguam volcanic center, central Aleutian arc: closed-system fractional crystallization of a basalt to rhyodacite eruptive suite

    Microsoft Academic Search

    Bradley S. Singer; James D. Myers; Carol D. Frost

    1992-01-01

    In contrast to adjacent volcanic centers of the modern central Aleutian arc, Seguam Island developed on strongly extended arc crust. K-Ar dates indicate that mid-Pleistocene, late-Pleistocene, and Holocene eruptive phases constitute Seguam. This study focuses on the petrology of the mid-Pleistocene, 1.07–07 Ma, Turf Point Formation (TPF) which is dominated by an unusual suite of porphyritic basalt and basaltic andesite

  15. Hawaiian Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Orr, Tim R.

    2008-01-01

    Lava from Kilauea volcano flowing through a forest in the Royal Gardens subdivision, Hawai'i, in February 2008. The Hawaiian Volcano Observatory (HVO) monitors the volcanoes of Hawai'i and is located within Hawaiian Volcanoes National Park. HVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Kilauea and HVO at http://hvo.wr.usgs.gov.

  16. Seismogenic structures activated during the pre-eruptive and intrusive swarms of Piton de la Fournaise volcano (La Réunion island) between 2008 and 2011

    NASA Astrophysics Data System (ADS)

    Battaglia, J.; Brenguier, F.

    2011-12-01

    Piton de la Fournaise is a frequently active basaltic volcano with more than 30 fissure eruptions since 1998. These eruptions are always preceded by pre-eruptive swarms of volcano-tectonic earthquakes which accompany dike propagation. Occasionally, intrusion swarms occur without leading to any eruption. From October 2008 to May 2011, as part of the research project Undervolc, a temporary network of 15 broadband stations has been installed on the volcano to complement the local monitoring network. We examined in detail the 6 intrusive and 5 pre-eruptive swarms which occurred during the temporary experiment. All the crises lasted for a few hours and only included shallow events clustered below the summit craters, around and above sea level, showing no signs of deeper magma transfers. These characteristics are common to most swarms observed at Piton de la Fournaise arising questions about the origin of the seismicity which seems to be poorly linked with dike propagation. With the aim to identify the main seismogenic structures active during the swarms, we applied precise earthquake detection and classification techniques based on waveform cross-correlation. For each swarm, the onsets of all transients, including small amplitude ones, have been precisely detected at a single station by scanning the continuous data with reference waveforms. The classification of the detected transients indicates the presence of several families of similar earthquakes. The two main families (F01 and F02) include several hundred events. They are systematically activated at the beginning of each pre-eruptive swarm but are inactive during the intrusive ones. They group more than 50 percent of the detected events for the corresponding crises. The other clusters are mostly associated with single swarms. To determine the spatial characteristics of the structures corresponding to the main families, we applied precise relocation techniques. Based on the one-station classification, the events have first been picked at all available stations by cross-correlating waveforms with those of master events whose arrival times have been manually determined. All events have been located using a 3D velocity model to determine accurate hypocentral azimuths and take-off angles. Precise relative locations have been computed for each multiplet using cross-correlation delays calculated for all available stations between all pairs of events. The results indicate the presence at sea level of a major structure grouping families F01 and F02 and describing an East-West elongated pattern with sub-vertical extension. Small scale earthquake migrations, mostly horizontal, occur during the pre-eruptive swarms along that structure. The smaller multiplets define vertically elongated patterns extending around and above the main F01-F02 multiplet. Our results show that different processes are involved in pre-eruptive and intrusive crises and that a structure located around 2.5 km below the summit controls the occurrence of recent eruptions of Piton de la Fournaise volcano.

  17. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

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

  18. Eradication of Aleutian disease of mink by eliminating positive counterimmunoelectrophoresis test reactors.

    PubMed Central

    Cho, H J; Greenfield, J

    1978-01-01

    The counterimmunoelectrophorsis test was applied on three Aleutian disease virus-infected mink ranches for the detection of specific Aleutian disease virus antibody. All mink on the ranches were tested during the pelting season and before the breeding season for 4 consecutive years. Aleutian disease has been eliminated from the three commercial mink ranches by culling out all mink that were positive for Aleutian disease virus antibody. PMID:203601

  19. SITE SELECTION AND FORAGING BEHAVIOR OF ALEUTIAN CANADA GEESE IN A NEWLY COLONIZED

    E-print Network

    Black, Jeff

    , Humboldt State University, Arcata, CA 95521, USA Abstract: The once endangered Aleutian Canada goose, Los Banos, CA 93635, USA #12;107 The recovery of the Aleutian Canada goose population is 1 of the most106 SITE SELECTION AND FORAGING BEHAVIOR OF ALEUTIAN CANADA GEESE IN A NEWLY COLONIZED SPRING

  20. Griddlestones from Adak Island, Alaska: Their provenance and the biological origins of organic residues from cooking

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Burned stone slabs, historically called griddlestones, were recovered from Components 1 (2390-2590 RCYPB) and 2 (170-415 RCYBP) at archaeological site ADK-011 on Adak Island, Aleutian Islands, Alaska. The griddlestones show evidence of fire exposure and have a dark, often greasy, matrix of decompose...

  1. Serpentinites and low-K island arc meta-volcanic rocks in the Lower Köli Nappe of the central Scandinavian Caledonides: Late Cambrian-early Ordovician serpentinite mud volcanoes in a forearc basin?

    NASA Astrophysics Data System (ADS)

    Grimmer, Jens C.; Greiling, Reinhard O.

    2012-05-01

    The late Cambrian to early Ordovician meta-volcanic rocks of the Caledonian Lower Köli Nappe consist mainly of tholeiitic low-K island arc basalts, andesites, and rhyodacites. The dominance of rhyodacites in this meta-volcanic succession raises the question on whether fractional crystallization or partial melting were involved in their origin. Low Mg#, low Cr and Ni contents and compositional trends imply at least two stages of fractional crystallization for the origin of the meta-volcanic rocks. Sedimentary-hosted serpentinites occur stratigraphically below and above the meta-volcanic rocks raising the question on their origin. Geochemical data indicate strongly depleted harzburgitic-dunitic peridotite as precursor rocks of the serpentinites. Unusually high contents of As, Sb, Pb in these serpentinites are not in agreement with a depleted mantle geochemistry, but indicate enrichment by fluids from the subducted slab during serpentinization in the mantle wedge. The massive, detrital, and in places fossiliferous serpentinite bodies within the sedimentary host-rocks point to former serpentinite mud volcanoes within a non-accretionary forearc. Therefore it is suggested that the highly fractionated volcanic rocks were emplaced as lava flows and shallow intrusions in sedimentary forearc successions implying that the Lower Köli Nappe was part of a much larger trench-arc complex involving at least the immediate hanging wall Middle Köli Stikke Nappe.

  2. The Shallow Plumbing System of Piton de la Fournaise Volcano (La Réunion island, Indian Ocean) Revealed by the Major 2007 Caldera Forming Eruption (Invited)

    NASA Astrophysics Data System (ADS)

    Di Muro, A.; Metrich, N.; Daniele, V.; Rosi, M.; Armienti, P.; Fougeroux, T.; Deloule, E.; Arienzo, I.; Civetta, L.

    2013-12-01

    The 2007 eruption represents a major event in the recent history of Piton de la Fournaise volcano because it produced: i) the most voluminous lava field (at least 0.21 km3), ii) the most intense lava fountaining activity (>200 m high), iii) the largest SO2 plume (>230 kt), iv) the largest summit collapse (1 km wide x 0.34 km deep) and v) the main flank slip event (up to 1.4 m eastwards) ever documented at PdF. The bulk magma volume extruded during the 2007 eruptive sequence is similar to that emitted during the entire 1998-2006 period. As a whole, the volume of magma emitted during the whole 1998-2007 activity cycle is remarkably close to that estimated (~0.35 km3) for the shallow plumbing system of Piton de la Fournaise. The 2007 eruptive sequence consisted of three successive phases (February, March and April). The main caldera forming phase of April ended a 9 years long period (1998-2007) of continuous edifice inflation and frequent eruptive activity (3 eruptions per year on average). On the contrary, post-2007 activity punctuates a trend of continuous deflation and consists of small-volume summit eruptions of moderate/low MgO magmas and frequent shallow magma intrusions. The 2007 lavas and pyroclasts cover the complete range of textures and crystal content an composition typically found in PdF products. The broad range of textures and the large volumes of pyroclasts, lava and gas emitted in 2007 provide an unique and exceptional record of the time-integrated evolution of PdF magma, and represent an unique opportunity to image the volcano plumbing system and bring new constraints on the processes controlling its magmatic and volatile budget. We here address these issues by using an unprecedented geochemical dataset (major, volatile and trace elements, Sr-Nd isotopes) on bulk rocks, minerals, glass inclusions and glass matrices from a very detailed sample set, representative of the time evolution of extruded magma during the entire 2007 eruptive sequence.

  3. Newberry Volcano—Central Oregon's Sleeping Giant

    USGS Publications Warehouse

    Donnelly-Nolan, Julie M.; Stovall, Wendy K.; Ramsey, David W.; Ewert, John W.; Jensen, Robert A.

    2011-01-01

    Hidden in plain sight, Oregon's massive Newberry Volcano is the largest volcano in the Cascades volcanic arc and covers an area the size of Rhode Island. Unlike familiar cone-shaped Cascades volcanoes, Newberry was built into the shape of a broad shield by repeated eruptions over 400,000 years. About 75,000 years ago a major explosion and collapse event created a large volcanic depression (caldera) at its summit. Newberry last erupted about 1,300 years ago, and present-day hot springs and geologically young lava flows indicate that it could reawaken at any time. Because of its proximity to nearby communities, frequency and size of past eruptions, and geologic youthfulness, U.S. Geological Survey scientists are working to better understand volcanic activity at Newberry and closely monitor the volcano for signs of unrest.

  4. Volcano Lovers

    NSDL National Science Digital Library

    David Tenenbaum

    1997-01-02

    This Why Files article explores volcanoes and volcanic eruptions. Topics covered include: Alaska's Pavlof and its threat to jet engines; Mexico City's restless neighbor, Popocatepetl (El Popo); underground volcanic processes; modern forecasting of eruptions; various volcanic phenomena and features; large flood basalt areas around the world; California's volcanically active area, Long Valley Caldera and Mammoth Mountain; Indonesia's Krakatau eruption in 1883, which was the world's largest historical eruption; Krakatau's ecological contribution to the study of colonization of sterile lands; and central Mexico's Paricutin which was witnessed emerging from a farmer's field in 1943. Three scientists were interviewed for this article.

  5. Plant growth promoting capability and genetic diversity of bacteria isolated from mud volcano and lime cave of Andaman and Nicobar Islands

    PubMed Central

    Venkadesaperumal, Gopu; Amaresan, Natrajan; Kumar, Krishna

    2014-01-01

    Twenty four bacterial strains from four different regions of mud volcano and lime cave were isolated to estimate their diversity, plant growth promoting and biocontrol activities to use them as inoculant strains in the fields. An excellent antagonistic effect against four plant pathogens and plant growth promoting properties such as IAA production, HCN production, phosphate solubilization, siderophore production, starch hydrolysis and hydrolytic enzymes syntheses were identified in OM5 (Pantoea agglomerans) and EM9 (Exiguobacterium sp.) of 24 studied isolates. Seeds (Chili and tomato) inoculation with plant growth promoting strains resulted in increased percentage of seedling emergence, root length and plant weight. Results indicated that co-inoculation gave a more pronounced effects on seedling emergence, secondary root numbers, primary root length and stem length, while inoculation by alone isolate showed a lower effect. Our results suggest that the mixed inocula of OM5 and EM9 strains as biofertilizers could significantly increase the production of food crops in Andaman archipelago by means of sustainable and organic agricultural system. PMID:25763031

  6. Plant growth promoting capability and genetic diversity of bacteria isolated from mud volcano and lime cave of Andaman and Nicobar Islands.

    PubMed

    Venkadesaperumal, Gopu; Amaresan, Natrajan; Kumar, Krishna

    2014-01-01

    Twenty four bacterial strains from four different regions of mud volcano and lime cave were isolated to estimate their diversity, plant growth promoting and biocontrol activities to use them as inoculant strains in the fields. An excellent antagonistic effect against four plant pathogens and plant growth promoting properties such as IAA production, HCN production, phosphate solubilization, siderophore production, starch hydrolysis and hydrolytic enzymes syntheses were identified in OM5 (Pantoea agglomerans) and EM9 (Exiguobacterium sp.) of 24 studied isolates. Seeds (Chili and tomato) inoculation with plant growth promoting strains resulted in increased percentage of seedling emergence, root length and plant weight. Results indicated that co-inoculation gave a more pronounced effects on seedling emergence, secondary root numbers, primary root length and stem length, while inoculation by alone isolate showed a lower effect. Our results suggest that the mixed inocula of OM5 and EM9 strains as biofertilizers could significantly increase the production of food crops in Andaman archipelago by means of sustainable and organic agricultural system. PMID:25763031

  7. Episodes of aleutian ridge explosive volcanism.

    PubMed

    Hein, J R; Scholl, D W; Miller, J

    1978-01-13

    Earlier workers have overlooked deep-sea bentonite beds when unraveling the Cenozoic volcanic history of an area. In the North Pacific, identification of Miocene and older volcanic episodes is possible only if both altered (bentonite) and unaltered ash beds are recognized. Our study, which includes bentonite beds, shows that volcanism on the Aleutian Ridge and Kamchatka Peninsula has been cyclic. Volcanic activity seems to have increased every 2.5 x 10(6) years for the past 10 x 10(6) years and every 5.0 x 10(6) years for the time span from 10 to 20 x 10(6) years ago. The middle and late Miocene and the Quaternary were times of greatly increased volcanic activity in the North Pacific and elsewhere around the Pacific Basin. The apparent absence of a volcanic record before the late Miocene at Deep Sea Drilling Project site 192 is the result not of plate motion, as suggested by Stewart and by Ninkovich and Donn, but rather of the diagenesis of ash layers. Major, apparently global volcanic episodes occurred at least twice in the last 20 x 10(6) years. Yet, only one major glacial epoch (the Pleistocene) has occurred. Therefore, even though glaciation coincided with an increase in Quaternary volcanism, the increased volcanism itself may not have been the primary cause of global cooling. PMID:17812931

  8. Heavy metals in fish from the Aleutians: interspecific and locational differences.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Jeitner, Christian; Pittfield, Taryn; Donio, Mark

    2014-05-01

    The objectives of this study were to examine levels of arsenic, cadmium, lead, mercury and selenium in edible tissue of seven species of marine fish collected from several Aleutian islands (in 2004) to determine: (1) interspecific differences, (2) locational differences (among Aleutian Islands), (3) size-related differences in any metal levels within a species, and (4) potential risk to the fish or to predators on the fish, including humans. We also compared metals levels to those of three other fish species previously examined in detail, as well as examining metals in the edible tissue of octopus (Octopus dofleini). Octopus did not have the highest levels of any metal. There were significant interspecific differences in all metal levels among the fish species, although the differences were less than an order of magnitude, except for arsenic (mean of 19,500 ppb in Flathead sole, Hippoglossoides elassodon). Significant intraisland variation occurred among the four sites on Amchitka, but there was not a consistent pattern. There were significant interisland differences for some metals and species. Mercury levels increased significantly with size for several species; lead increased significantly for only one fish species; and cadmium and selenium decreased significantly with size for halibut (Hippoglossus stenolepis). The Alaskan Department of Health and Social Services supports unrestricted consumption of most Alaskan fish species for all people, including pregnant women. Most mean metal concentrations were well below the levels known to adversely affect the fish themselves, or predators that consume them (including humans), except for mercury in three fish species (mean levels just below 0.3 ppm), and arsenic in two fish species. However, even at low mercury levels, people who consume fish almost daily will exceed guideline values from the Centers for Disease Control and the Environmental Protection Agency. PMID:24727640

  9. High resolution dating of moraines on Kodiak Island, Alaska links Atlantic and North Pacific climatic changes during the late glacial

    SciTech Connect

    Mann, D.H. (Univ. of Alaska, Fairbanks, AK (United States). Alaska Quaternary Center)

    1992-01-01

    Much less is known about the paleoclimate and paleoceanography of the North Pacific than the North Atlantic despite the North Pacific's important role in the global ocean-climate system. Kodiak Island lies in the northwestern Gulf of Alaska astride the eastern end of the Aleutian Low. On southwestern Kodiak Island, coastal bluffs section a series of moraines, kettle ponds, and bogs formed between 15 and 9 ka BP. Distinctive tephras from volcanoes on the Alaska Peninsula provide time-lines within the stratigraphy. Deformation events recorded in sediment stacks from basins within glaciotectonic landforms allows precise dating of glacial events. An ice cap occupied the Kodiak archipelago during the last glaciation. Three glacial advances of the southwestern margin of this ice cap occurred after 15 ka BP. At 13.4 ka, piedmont ice lobes formed large push moraines extending into Shelikof Strait during the Low Cape Advance. The less-extensive Tundra Advance culminated between 12 and 11.7 ka BP followed by glacier retreat then readvance to form the prominent Olga Moraine system between 11 and 10 ka BP. The timing of the Tundra and Olga Advances correlates closely with that of the Older and Younger Dryas cold episodes in northwestern Europe suggesting that these climatic oscillations were synchronous throughout the northern hemisphere.

  10. Hawaiian Volcano Observatory

    NSDL National Science Digital Library

    As part of the US Geological Survey, the Hawaiian Volcano Observatory (HVO) is charged with monitoring and researching volcanoes in Hawaii. The site provides current activity reports, hazard information, and a history of the two main volcanoes, Kilauea and Mauna Loa. In addition, the site provides information on three other volcanoes that are either active or potentially active. Visitors can also learn about earthquakes in Hawaii and the particular hazards posed by volcanos. Captivating photos help bring the volcanoes to life. Visitors can patronize the Photo Gallery for additional volcano photos. Cross links to additional information and sites are provided on every page.

  11. 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 ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

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

  12. The Electronic Volcano

    NSDL National Science Digital Library

    The Electronic Volcano offers links to many types of information on active volcanoes, such as maps, photographs, full texts of dissertations and a few elusive documents. The Electronic Volcano will guide you to resources in libraries or resources on other information servers including catalogs of active volcanoes, datasets for literature citations, electronic and hard-copy journals, visual information, maps, observatories and institutions, and a volcano name and country index.

  13. Earth Layers and Volcanoes

    NSDL National Science Digital Library

    brookeshallow

    2011-04-13

    Why do we have volcanoes? Use the information on the websites to answer the questions on the worksheet. Worksheet First, review the layers of the earth. Labeling the layers game Next, go through the maze and read the information given. Magic School Bus volcano game Now, study the different shapes of volcanoes. Click enter, then volcano types in the menu. Read about the 3 types of volcanoes. Discovery Kids Games Finally, watch ...

  14. Alaska - Kamchatka Connection in Volcano Monitoring, Research, and Education

    NASA Astrophysics Data System (ADS)

    Izbekov, P. E.; Gordeev, E.; Eichelberger, J. C.; Neal, C. A.

    2009-12-01

    The Aleutian-Kamchatka portion of the Pacific Rim of Fire spans ~4400 km. This segment contains more than 80 active volcanoes and averages 4-6 eruptions per year. Resulting ash clouds travel for hundreds to thousands of kilometers defying political borders. To mitigate volcano hazard to aviation and local communities, the Alaska Volcano Observatory (AVO) and the Institute of Volcanology and Seismology (IVS), in partnership with the Kamchatkan Branch of the Geophysical Survey of the Russian Academy of Sciences (KBGS), have established a collaborative program with three important components: (1) volcano monitoring with rapid information exchange, (2) cooperation in research projects at active volcanoes, and (3) a series of volcanological schools for students and young scientists. Cooperation in volcano monitoring includes dissemination of daily information on the state of volcanic activity in neighboring regions, satellite and visual data exchange, as well as sharing expertise and technologies between AVO and the Kamchatkan Volcanic Eruption Response Team (KVERT), formed in 1993 under the auspices of both IVS and KBGS. Collaboration in scientific research is best illustrated by involvement of AVO, IVS, and KBGS faculty and graduate students in mutual international studies. One of the most recent examples is the NSF-funded Partnerships for International Research and Education (PIRE)-Kamchatka project focusing on multi-disciplinary study of Bezymianny volcano in Kamchatka. This international project is one of many that have been initiated as a direct result of a bi-annual series of meetings known as Japan-Kamchatka-Alaska Subduction Processes (JKASP) workshops that we organize together with colleagues from Hokkaido University, Japan. The most recent JKASP meeting was held in June 2009 in Fairbanks, Alaska and brought together more than 150 scientists and students. The key educational component of our collaborative program is the continuous series of international volcanological schools organized in partnership with the Kamchatka State University. Each year more than 40 students and young scientists participate in our annual field trips to Katmai, Alaska and Mutnovsky, Kamchatka.

  15. 4D seismic structure beneath Spurr volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Jakovlev, Andrey; Koulakov, Ivan; West, Michael

    2013-04-01

    Mount Spurr is a large volcano located 125 km west of Anchorage, Alaska. This dominantly andesitic stratovolcano with summit elevation of 3374 m is the highest volcano of the Aleutian Arc. Two historical eruptions of Spurr volcano have occurred in 1953 and 1992. Moreover, from July 2004 to February 2006 continuous non-eruptive activity was observed. Since 1988 the Alaska Volcano Observatory (AVO) collects information about Alaska seismicity. In this work we present evolution of the seismic structure beneath Spurr volcano obtained from 4D seismic tomography. In total 222605 rays (129387 P and 93218 S rays) coming from 17068 earthquakes and registered by 26 station of AVO seismic network were used for the tomographic inversion. After analysis of the seismic and volcano activity, 5 time periods were chosen. Variations of P and S wave velocity anomalies and Vp/Vs ratio in this 5 time periods were obtained after simultaneous iterative inversion of one combined matrix. Smoothness of the velocity anomalies variation in space and time are controlled by two additional matrix block. Results reveal clear correlation of the seismic structure and volcanic activity. In the first (October 1989 - July 1996) and fourth (January 2004 - January 2007) time periods, characterized by high activity, a prominent vertical channel directly beneath volcano is observed on the vertical sections. This channel is characterized by very high values of Vp/Vs ratio (increased P wave and decreased S wave velocities). During the three other periods with no volcanic activity, when the relaxation of the media took place, seismic structure becomes more homogeneous without strong velocity anomalies. Special attention is paid to estimation of the model resolution in different time periods and analysis of possible artifacts due to different ray coverage in different periods. Therefore a lot synthetic and real data tests were performed.

  16. Super Volcano

    NSDL National Science Digital Library

    Deep beneath the surface of Earth lies one of the most destructive and yet least understood of the natural forces on the planet: the super volcano. This radio broadcast presents discussions with scientists at Yellowstone National Park who are investigating this potentially devastating natural phenomenon. Yellowstone National Park is one of the largest supervolcanoes in the world. It last erupted 640,000 years ago and scientists are now predicting that the next eruption may not be far off. To discover more, a new volcanic observatory has been built in the park to monitor the extreme volcanic activity going on beneath the surface of this much visited destination. The broadcast is 30 minutes in length.

  17. Santorini Volcano

    NASA Astrophysics Data System (ADS)

    Heiken, Grant

    What is it about Santorini (Thera) that attracts volcanologists? This small archipelago in the Aegean has captivated volcanic pilgrims since Fouque published his geologic study of the volcanic field in 1879 [Fouqué, 1879].It must be the combination of its spectacular setting, rising out of the blue waters of the Aegean, the remarkable exposures that lay open its violent past for everyone to see, or possibly the slower pace of life and remarkable Greek hospitality Perhaps it is the Lower Bronze Age town of Akrotiri, destroyed yet preserved by a large explosive eruption 3600 years ago. There are thousands of volcanoes yet to be studied on our planet, but for 140 years, groups of volcanologists have regularly visited this flooded caldera complex to add yet another bit of information to the foundation laid by Fouqué.

  18. Eruption dynamics of the 7.7 ka Driftwood pumice-fall suggest mafic injection is a common eruption mechanism for Makushin Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Lerner, A.; Crowley, P.; Hazlett, R. W.; Nicolaysen, K. E.

    2010-12-01

    Makushin Volcano on Unalaska Island, AK is potentially the most threatening volcano in the Aleutian chain, being close to the largest Aleutian towns of Dutch Harbor and Unalaska. This study reports the eruption chronology and triggering mechanism for the most recent highly explosive event, the 7.7 ka Driftwood Pumice-fall event. The Driftwood Pumice reaches thicknesses of over 2 m, and isopach contours estimate a total deposit volume of 0.3-0.9 km3, covering an area of at least 8100 km2. These reconstructions show an eruption on the scale of the 1980 Mt. St. Helens eruption, with a VEI of 4-5. In the field, the deposit was divided into four stratigraphic horizons from bottom to top, and tephra within these layers becomes systematically more mafic upward through the section, ranging from a basal low-SiO2 dacite (64 wt.% SiO2) to an upper medium-SiO2 andesite (61.5 wt.% SiO2). High-Ca plagioclase (An75-83) and high-Mg olivine (Mg69-75) grains within the pumice are in great disequilibrium with the dacitic glass (64-69 wt.% SiO2), suggesting their origin in a more mafic magma. Geochemical trends, disequilibrium mineral populations, and mineral zonation patterns within these plagioclase and olivine xenocrysts show evidence of magma mixing between a bulk siliceous magma chamber and a mafic injection. The amount of the mafic component increases upward within the deposit, ranging from 0-25% throughout the section. The mafic injection is calculated to have been ~110-200 °C hotter than the siliceous magma chamber. The thermal pulse provided by the injection likely initiated convection and volatile exsolution within the siliceous magma body, ultimately causing the Driftwood Pumice eruption. Diffusion rates based on the thickness of lower-Mg rim zonations (<10 µm thick rims of Mg64) in the olivine xenocrysts show a lag-time of ~1 year between the basaltic injection and the resulting eruption. Similar delays between mafic injections and eruptions are seen in numerous other volcanic systems where magma mixing has been cited as the eruption trigger. The Driftwood Pumice is stratigraphically sandwiched between numerous smaller ashfalls, many of which consist of light-dark ash couplets. The color and compositional differences between the layers of these ash couplets are similar to differences within the Driftwood Pumice horizons, though the Driftwood Pumice is significantly thicker than the couplets. The repeated occurrences of light tephra overlain by dark, more mafic tephra suggest that magma mixing via a mafic injection is a common mechanism for sparking Makushin eruptions.

  19. Seismicity and seismic structure at Okmok Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Ohlendorf, Summer J.; Thurber, Clifford H.; Pesicek, Jeremy D.; Prejean, Stephanie G.

    2014-05-01

    Okmok volcano is an active volcanic caldera located on the northeastern portion of Umnak Island in the Aleutian arc, with recent eruptions in 1997 and 2008. The Okmok area had ~900 locatable earthquakes between 2003 and June 2008, and an additional ~600 earthquakes from the beginning of the 2008 eruption to mid 2009, providing an adequate dataset for seismic tomography. To image the seismic velocity structure of Okmok, we apply waveform cross-correlation using bispectrum verification and double-difference tomography to a subset of these earthquakes. We also perform P-wave attenuation tomography using a spectral decay technique. We examine the spatio-temporal characteristics of seismicity in the opening sequence of the 2008 eruption to investigate the path of magma migration during the establishment of a new eruptive vent. We also incorporate the new earthquake relocations and three-dimensional (3D) velocity model with first-motion polarities to compute focal mechanisms for selected events in the 2008 pre-eruptive and eruptive periods. Through these techniques we obtain precise relocations, a well-constrained 3D P-wave velocity model, and a marginally resolved S-wave velocity model. We image a main low Vp and Vs anomaly directly under the caldera consisting of a shallow zone at 0-2 km depth connected to a larger deeper zone that extends to about 6 km depth. We find that areas of low Qp are concentrated in the central to southwestern portion of the caldera and correspond fairly well with areas of low Vp. We interpret the deeper part of the low velocity anomaly (4-6 km depth) beneath the caldera as a magma body. This is consistent with results from ambient noise tomography and suggests that previous estimates of depth to Okmok's magma chamber based only on geodetic data may be too shallow. The distribution of events preceding the 2008 eruption suggest that a combination of overpressure in the zone surrounding the magma chamber and the introduction of new material from below were jointly responsible for the explosive eruption. Magma escaping from the top of the main magma chamber likely reacted with both a smaller shallow pod of magma and groundwater on its way up below the Cone D area. The earthquakes in the 2008 pre-eruptive and eruptive periods are found to have a mixture of strike-slip, oblique normal, and oblique thrust mechanisms, with a dominant P-axis orientation that is nearly perpendicular to the regional tectonic stress. This may indicate that the stresses related to magmatic activity locally dominated regional tectonic forces during this time period.

  20. The hazards -and benefits -of volcanic eruptions on oceanic islands

    E-print Network

    Geist, Dennis

    The hazards - and benefits - of volcanic eruptions on oceanic islands Kathy Cashman University-related island volcanoes; when they occur they can be disastrous Santorini c. 3600 ybp- demise of the Minoans controlled by magma ascent rate) Pioli et al. (2009) Plinian Lava flows Arc volcanoes #12;How common

  1. Detecting hidden volcanic explosions from Mt. Cleveland Volcano, Alaska with infrasound and ground-couples airwaves

    USGS Publications Warehouse

    De Angelis, Slivio; Fee, David; Haney, Matthew; Schneider, David

    2012-01-01

    In Alaska, where many active volcanoes exist without ground-based instrumentation, the use of techniques suitable for distant monitoring is pivotal. In this study we report regional-scale seismic and infrasound observations of volcanic activity at Mt. Cleveland between December 2011 and August 2012. During this period, twenty explosions were detected by infrasound sensors as far away as 1827 km from the active vent, and ground-coupled acoustic waves were recorded at seismic stations across the Aleutian Arc. Several events resulting from the explosive disruption of small lava domes within the summit crater were confirmed by analysis of satellite remote sensing data. However, many explosions eluded initial, automated, analyses of satellite data due to poor weather conditions. Infrasound and seismic monitoring provided effective means for detecting these hidden events. We present results from the implementation of automatic infrasound and seismo-acoustic eruption detection algorithms, and review the challenges of real-time volcano monitoring operations in remote regions. We also model acoustic propagation in the Northern Pacific, showing how tropospheric ducting effects allow infrasound to travel long distances across the Aleutian Arc. The successful results of our investigation provide motivation for expanded efforts in infrasound monitoring across the Aleutians and contributes to our knowledge of the number and style of vulcanian eruptions at Mt. Cleveland.

  2. Management and Conservation Article Expensive Traditions: Energy Expenditure of Aleutian

    E-print Network

    Black, Jeff

    resources deteriorates geese are likely to seek improved foraging conditions, especially during spring, and daily energy expenditure in addition to quantity and quality of foods. (JOURNAL OF WILDLIFE MANAGEMENT spring staging area for Aleutian geese was on dairy and cattle pastures of Del Norte County, California

  3. Types of Volcanoes

    NSDL National Science Digital Library

    This volcano resource introduces the six-type classification system and points out weaknesses of the classic three-type system. The six types of volcanoes are shield volcanoes, strato volcanoes, rhyolite caldera complexes, monogenetic fields, flood basalts, and mid-ocean ridges. For each type of volcano there is a description of both structure and dynamics along with examples of each. You can account for more than ninty percent of all volcanoes with these six types. Additionally, any system will be more useful if you use modifiers from the other potential classification schemes with the morphological types.

  4. Potential landslide activity affecting the archaeological site of Orongo (Easter Island-Chile): preliminary analysis

    Microsoft Academic Search

    C. Margottini; G. Delmonaco; D. Spizzichino; O. Pandolfi; R. Crisostomo; S. Nohe

    2009-01-01

    Easter Island forms part of the Easter Line, a continuous latitudinal chain of volcanic seamounts and islands in the Pacific Sea. The island's roughly triangular shape is determined by the merging of lava flows produced by its three main volcanoes (Rano Kau, Terevaka, Poike) which form its main mass. The Rano Kau volcano, sited in the SW vertex of the

  5. Life on the Edge: Holocene Tephra Stratigraphy of Tanginak Anchorage, Sitkalidak Island, Kodiak Archipelago, Alaska

    NASA Astrophysics Data System (ADS)

    Mahrt, E.; Bourgeois, J.; Fitzhugh, J. B.

    2004-12-01

    Geologic hazards associated with volcanism in the North Pacific have profound if usually temporary effects on the environment and human populations. Ash falls associated with these events are often preserved across large areas providing time specific markers. In the past century, volcanic activity and its effects in the North Pacific have been recorded, but much of the Holocene volcanic record in the Alaskan region is still being investigated. The Kodiak Archipelago, while not volcanic itself, is located near both Aleutian and Alaskan peninsula volcanoes. However, little has been published about the Holocene tephrochronology of the Kodiak region. This study focuses on the area around Tanginak Spring Site (KOD481). Located on Sitkalidak Island it is the earliest known human occupation in the Kodiak archipelago. We are documenting Holocene environmental changes on Sitkalidak Island and relating these changes to the archaeological record. As part of this work, we will establish a local tephrochronology using stratigraphy and geochemistry which will allow us to better correlate sedimentary changes across large areas as well as study human interaction with ashfall events. Herein we report a preliminary tephrochronology in peat excavations on Sitkalidak Island dating back to the earliest Holocene. Dates are radiocarbon years BP on peat directly below tephra. Marker tephra present in our reference sections are Katmai 1912, light gray (historic?), medium gray (3370), medium gray (3720), beige 1 (4340), apricot (5390), beige 3 (6790), black (9280), and white (11,520). Geochemical and petrographic analysis will help to determine with which volcanic events these tephra are associated. Establishing a local tephrochronology is important not only for local correlation but also to ascertain the tephra stratigraphy of the Kodiak Archipelago and beyond. The frequency of tephra in Tanginak Anchorage sections suggests that tephra will be a very useful stratigraphic tool in this region.

  6. The origin of the Hawaiian Volcano Observatory

    SciTech Connect

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

    2011-05-15

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

  7. Relative velocity changes using ambient seismic noise at Okmok and Redoubt volcanoes, Alaska

    NASA Astrophysics Data System (ADS)

    Bennington, N. L.; Haney, M. M.; De Angelis, S.; Thurber, C. H.

    2013-12-01

    Okmok and Redoubt are two of the most active volcanoes in the Aleutian Arc. Leading up to its most recent eruption, Okmok, a shield volcano on Umnak Island, showed precursors to volcanic activity only five hours before it erupted explosively in July 2008. Redoubt, a stratovolcano located along the Cook Inlet, displayed several months of precursory activity leading up to its March 2009 eruption. Frequent activity at both volcanoes poses a major hazard due to heavy traffic along the North Pacific air routes. Additionally, Okmok is adjacent to several of the world's most productive fisheries and Redoubt is located only 110 miles SW of Anchorage, the major population center of Alaska. For these reasons, it is imperative that we improve our ability to detect early signs of unrest, which could potentially lead to eruptive activity at these volcanoes. We take advantage of continuous waveforms recorded on seismic networks at Redoubt and Okmok in an attempt to identify seismic precursors to the recent eruptions at both volcanoes. We perform seismic interferometry using ambient noise, following Brenguier et al. (2008), in order to probe the subsurface and determine temporal changes in relative seismic velocity from pre- through post-eruption, for the 2008 Okmok and 2009 Redoubt eruptions. In a preliminary investigation, we analyzed 6 months of noise cross-correlation functions averaged over 10-day intervals leading up to the 2009 eruption at Redoubt. During February 2009, station pairs RSO-DFR and RDN-RSO showed a decrease in seismic velocity of ~0.02%. By the beginning of March, the relative velocity changes returned to background levels. Stations RSO and RDN are located within the summit breach, and station DFR is to the north. Although these results are preliminary, it is interesting to note that the decrease in seismic velocity at both station pairs overlaps with the time period when Grapenthin et al. (2012) hypothesize magma in the mid-to-deep crustal reservoir was reheated and migrated to a second shallow reservoir between 2 and 4.5 km depth. This hypothesized shallow magma reservoir is within the sensitivity depth of our ambient noise analysis, and thus the decrease in seismic velocity may be associated with magma movement at shallow depths underneath Redoubt. At the onset of eruption, the relative velocity change at station pair RDN-RSO decreased by ~0.03% while that at RSO-DFR remained at background levels. Notably, this decrease in seismic velocity is observed only at the station pair with a propagation path that traverses the summit breach. Our investigation continues as we search for time variations in the ambient seismic noise signal preceding and following the 2008 Okmok and 2009 Redoubt eruptions and endeavor to identify what those changes may represent.

  8. Ol Doinyo Lengai Volcano

    USGS Multimedia Gallery

    Scientists from the Volcano Disaster Assistance Program team and the Geological Survey of Tanzania take a sample of the most recent ashfall from Ol Doinyo Lengai as the volcano looms in the background....

  9. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

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

  10. Iceland: Grímsvötn Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Grímsvötn Volcano Injects Ash into the Stratosphere     ... p.m. local time (1730 UTC) on Saturday, May 21, 2011. The volcano, located approximately 140 miles (220 kilometers) east of the capital ...

  11. Spatial Analysis of Volcanoes at Convergent Margins on Earth

    NASA Astrophysics Data System (ADS)

    Roberts, R. V.; de Silva, S. L.; Meyers, M.

    2009-12-01

    One of the most obvious patterns seen on the surface of the terrestrial planets is the distribution of volcanoes. On Earth, most volcanoes are distributed in volcanic “arcs” that signal the primary relationship between subduction and volcanism. The distributions of major composite volcanoes in volcanic arcs are thought to reflect the primary magmatic pathways from source to surface. Understanding these patterns therefore may allow fundamental controls on the organization of magmatic plumbing in arcs to be identified. Using a control dataset from the Central Volcanic Zone of the Andes (de Silva and Francis, 1991; Springer-Verlag) we have examined several popular approaches to spatial analysis of volcano distribution in several volcanic arcs (Aleutian, Alaskan, Central American, Northern and Southern volcanic zones of the Andes). Restricting our analysis to major volcanoes of similar age, we find that while clustering is visually obvious in many volcanic arcs it has been rejected as a primary signal by previous analytical efforts (e.g. Bremont d'Ars et al (1995)). We show that the fractal box or grid counting method used previously does not detect clusters and statistical methods such as the Kernel Density Analysis or Single-link Cluster Analysis are better suited for cluster detection. Utilizing both ARC GIS and Matlab to conduct density analyses in combination with statistical software SPlus for the appropriate hypothesis testing methods such as the pooled variance t-test, the Welch Modified two sample t-test, and the f-test we find evidence of clustering in four volcanic arcs whose crustal thickness is greater than or equal to 40 kilometres (Central America, CVZ, NVZ, SVZ). We suggest that clustering is the surface manifestation of upper crustal diffusion of primary magmatic pathways, which in other places manifests as a single volcano. The inter-cluster distance is a thus reflection of primary magmatic pathways and thus equivalent to inter-volcano distance. With this recognition in hand a more realistic analysis of volcano-spacing has been undertaken. We find a weak correlation between median volcano/cluster distance and crustal thickness when the crust is no thicker than 40 kilometres. At values of 40 kilometres and greater, there is instead a strong inverse correlation between crustal thickness and median spacing. With p-values all less than 0.05 and a 95% confidence interval, the two-sided two-sample t-tests show that there is a significant difference between the mean volcano/cluster distance for the CVZ and the mean distance for all other arc systems implicating a strong influence of the over thickened (70 to 80 km) crust in that region.

  12. How Volcanoes Work: Historical Eruptions

    NSDL National Science Digital Library

    Victor Camp

    This information about major volcanic eruptions in history covers events from the civilization-destroying explosion at Santorini in about 1630 BC, to the killing cloud of carbon dioxide at Lake Nyos Cameroon in 1986. The site documents the seven deadliest eruptions in history. Other eruptions include Mount Pelee on the island of Martinique in 1902, Mount Saint Helens in Washington State in 1980, Nevado Del Ruiz Columbia in 1985, the Mexican eruption of Paricutin in 1943, and the 1883 explosion that nearly obliterated the island of Krakatau in what is now Indonesia. For each eruption the site offers information about the type of volcano, the type of eruption, the products of the eruption, and the relation to plate tectonics. In addition, historical background is provided when appropriate.

  13. Interactive Volcano Studies and Education Using Virtual Globes

    NASA Astrophysics Data System (ADS)

    Dehn, J.; Bailey, J. E.; Webley, P.

    2006-12-01

    Internet-based virtual globe programs such as Google Earth provide a spatial context for visualization of monitoring and geophysical data sets. At the Alaska Volcano Observatory, Google Earth is being used to integrate satellite imagery, modeling of volcanic eruption clouds and seismic data sets to build new monitoring and reporting tools. However, one of the most useful information sources for environmental monitoring is under utilized. Local populations, who have lived near volcanoes for decades are perhaps one of the best gauges for changes in activity. Much of the history of the volcanoes is only recorded through local legend. By utilizing the high level of internet connectivity in Alaska, and the interest of secondary education in environmental science and monitoring, it is proposed to build a network of observation nodes around local schools in Alaska and along the Aleutian Chain. A series of interactive web pages with observations on a volcano's condition, be it glow at night, puffs of ash, discolored snow, earthquakes, sounds, and even current weather conditions can be recorded, and the users will be able to see their reports in near real time. The database will create a KMZ file on the fly for upload into the virtual globe software. Past observations and legends could be entered to help put a volcano's long-term activity in perspective. Beyond the benefit to researchers and emergency managers, students and teachers in the rural areas will be involved in volcano monitoring, and gain an understanding of the processes and hazard mitigation efforts in their community. K-12 students will be exposed to the science, and encouraged to participate in projects at the university. Infrastructure at the university can be used by local teachers to augment their science programs, hopefully encouraging students to continue their education at the university level.

  14. Volcanoes: Annenberg Media Project

    NSDL National Science Digital Library

    Volcanoes is an exhibit from the Annenberg Media Project that provides a wealth of information about volcanoes and includes sections such as Melting Rocks, the Dynamic Earth, and Forecasting. Interactive exercises enable the user to learn how rock turns into magma, how to locate volcanoes, and how to decide if building a project near a volcano is safe. Quicktime videos are used for each of the six categories to illustrate the points outlined in the text.

  15. The Volcano Adventure Guide

    Microsoft Academic Search

    Rosaly Lopes

    2005-01-01

    This guide contains vital information for anyone wishing to visit, explore, and photograph active volcanoes safely and enjoyably. Following an introduction that discusses eruption styles of different types of volcanoes and how to prepare for an exploratory trip that avoids volcanic dangers, the book presents guidelines to visiting 42 different volcanoes around the world. It is filled with practical information

  16. How Volcanoes Work

    NSDL National Science Digital Library

    Victor Camp

    2001-10-01

    This educational resource describes the science behind volcanoes and volcanic processes. Topics include volcanic environments, volcano landforms, eruption dynamics, eruption products, eruption types, historical eruptions, and planetary volcanism. There are two animations, over 250 images, eight interactive tests, and a volcano crossword puzzle.

  17. USGS Hawaiian Volcano Observatory

    USGS Multimedia Gallery

    The USGS Hawaiian Volcano Observatory is perched on the rim of Kilauea Volcano's summit caldera (next to the Thomas A. Jaggar Museum in Hawai'i Volcanoes National Park), providing a spectacular view of the active vent in Halema‘uma‘u Crater....

  18. Where are the Volcanoes?

    NSDL National Science Digital Library

    Jessica Fries-Gaither

    This formative assessment item discusses common misconceptions about volcano location around the world. Resources include background and content information as well as alignment to the National Science Education Standards. The probe could easily be modified to be used with a study of earthquakes instead of volcanoes. Teachers can access other resources including facts about volcanoes and lesson ideas.

  19. 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)

  20. Aerosol Lesson: Volcano Types

    NSDL National Science Digital Library

    This activity has students research a list of volcanoes and then write detailed information they researched under a column that identifies that type of volcano - Cinder Cone, Composite, or Shield. Included are a worksheet and a collection of links to referential websites about specific volcanoes.

  1. Focus: alien volcanos

    Microsoft Academic Search

    Michael Carroll; Rosaly Lopes

    2007-01-01

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

  2. Focus: alien volcanos

    NASA Astrophysics Data System (ADS)

    Carroll, Michael; Lopes, Rosaly

    2007-03-01

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

  3. Island of Hawaii, Hawaiian Archipelago

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This single photo covers almost all of the big island of Hawaii (19.5N, 155.5E) in the Hawaiian Archipelago. The active Kilauea Volcano and lava flow is under clouds and hardly visible at the lower right edge but the Mauna Loa volcano crater and its older lava flow is at the bottom center. The Kona Coast, that produces the only coffee grown in the United States, is to the left. Mauna Kea is the extinct volcano and lava flow in the right center.

  4. Constraints on the Composition and Hydrothermal Alteration History of the Pacific Lower Crust beneath the Hawaiian Islands: Geochemical Investigation of Gabbroic Xenoliths from Hualalai Volcano

    NASA Astrophysics Data System (ADS)

    Gao, R.; Lassiter, J. C.

    2013-12-01

    Understanding the composition and hydrothermal alteration history of the lower oceanic crust (LOC) can help constrain deep hydrothermal circulation at mid-ocean ridges, which may have a substantial impact on the thermal regime and magmatic processes at spreading centers. Previous studies of LOC primarily examined ophiolites or layer-3 gabbros exposed at the seafloor through faulting. These potentially have experienced secondary hydrothermal alteration in response to faulting, uplift and exposure. We examined major and trace element and isotopic compositions of a suite of gabbroic xenoliths derived from the 1800-1801 Kapulehu flow, Hualalai, Hawaii to constrain the composition and 'primary' hydrothermal alteration history of the in situ Pacific crust beneath the Hawaiian Islands (HI). Although most Hualalai gabbros have trace element and isotopic compositions consistent with derivation from Hualalai magmas, a subset has characteristics indicative of an origin from MORB-related melts. These gabbros contain LREE-depleted clinopyroxene, have Sr-Nd-Hf isotopic compositions that overlap the range of EPR basalts, and are geochemically distinct from Hualalai-related xenoliths and lavas. Despite the limited range recorded, plagioclase and clinopyroxene oxygen isotope compositions correlate well for both MORB-related and Hualalai-related gabbroic xenoliths. This suggests clinopyroxene and plagioclase are in equilibrium. The ?plag-cpx (~0.6-0.9‰) is consistent with closure temperatures of ~1170-1220 C.?18Ocpx (+4.9-5.3‰) of the MORB-related gabbros are negatively correlated with cpx 87Sr/86Sr, but not with 143Nd/144Nd or La/Sm. In contrast, ?18Oplag does not correlate with plag 87Sr/86Sr. Cpx Sr-isotopes may be affected by seawater alteration, which is not as apparent in plag due to higher Sr concentrations. However, the MORB-related gabbros have ?18O values that are largely in the range for normal, fresh MORB (?18Omelt/NMORB = +5.7-6.0‰, ?melt-cpx~0.7‰). This suggests that only limited hydrothermal circulation penetrated to the depth of the layer-3 LOC gabbros beneath the HI, which resulted in only minor hydrothermal alteration. This is in contrast with observations from several ophiolite sequences and fault-exposed gabbros, which show significantly greater hydrothermal alteration and larger shifts in ?18O from normal mantle values (e.g., ?18O down to +3.5‰; c.f., [1]). The greater alteration recorded in these samples may result from hydrothermal circulation triggered by faulting/uplift associated with their exposure. The relatively uniform and 'normal' ?18O values of the MORB-related gabbros also suggest that assimilation of Pacific crust by Hawaiian magmas ponding within the lower crust is unlikely to produce significant shifts in the magma oxygen isotope composition, and is therefore unlikely to account for the low ?18O values recorded in some Kea-trend lavas as previously proposed (c.f., [2]). [1] Gregory, R. T. & Taylor Jr, H. P., 1981, J. Geophys. Res., 86, 2737-2755. [2] Eiler, J. M., Farley, K. A., Valley, J. W., Hofmann, A. W. and Stolper, E. M, 1996, Earth Planet. Sci. Lett., 144, 453-468.

  5. Temporal Variation in Fish Mercury Concentrations within Lakes from the Western Aleutian Archipelago, Alaska

    PubMed Central

    Kenney, Leah A.; Eagles-Smith, Collin A.; Ackerman, Joshua T.; von Hippel, Frank A.

    2014-01-01

    We assessed temporal variation in mercury (Hg) concentrations of threespine stickleback (Gasterosteus aculeatus) from Agattu Island, Aleutian Archipelago, Alaska. Total Hg concentrations in whole-bodied stickleback were measured at two-week intervals from two sites in each of two lakes from June 1 to August 10, 2011 during the time period when lakes were ice-free. Across all sites and sampling events, stickleback Hg concentrations ranged from 0.37–1.07 µg/g dry weight (dw), with a mean (± SE) of 0.55±0.01 µg/g dw. Mean fish Hg concentrations declined by 9% during the study period, from 0.57±0.01 µg/g dw in early June to 0.52±0.01 µg/g dw in mid-August. Mean fish Hg concentrations were 6% higher in Loon Lake (0.56±0.01 µg/g dw) than in Lake 696 (0.53±0.01 µg/g dw), and 4% higher in males (0.56±0.01 µg/g dw) than in females (0.54±0.01 µg/g dw). Loon Lake was distinguished from Lake 696 by the presence of piscivorous waterbirds during the breeding season. Mercury concentrations in stickleback from Agattu Island were higher than would be expected for an area without known point sources of Hg pollution, and high enough to be of concern to the health of piscivorous wildlife. PMID:25029042

  6. Mt. Erebus: A Surprising Volcano: Grades K-1: Electronic Book

    NSDL National Science Digital Library

    Jessica Fries-Gaither

    This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. The text is written at a kindergarten through grade one reading level. This is an onscreen version that contains recorded narration allowing students to listen to the text as they read along. Highlighted vocabulary words have individually recorded definitions heard by clicking on the links.

  7. Sulphur output and magma degassing budget of Stromboli volcano

    Microsoft Academic Search

    P. Allard; J. Carbonnelle; N. Métrich; H. Loyer; P. Zettwoog

    1994-01-01

    STROMBOLI volcano in the Aeolian islands has been erupting continuously for more than 2,000 years1, and probably as many as 5,000, following a major flank collapse2,3. Here we describe air-borne measurements of the plume flux of SO2 during 1980-93, which show that the volcano emits very large amounts of gas, mostly by open-conduit degassing between explosive outbursts, while exuding little

  8. Short and Long Term Volcano Instability Studies at Concepcion Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Saballos, Jose A.

    Concepcion is the most active composite volcano in Nicaragua, and is located on Ometepe Island, within Lake Nicaragua. Moderate to small volcanic explosions with a volcanic explosivity index (VEI) of 1-2 have been characteristic of this volcano during the last four decades. Although its current activity is not violent, its volcanic deposits reveal stages of violent activity involving Plinian and sub-Plinian eruptions that deposited vast amounts of volcanic tephra in the Atlantic Ocean. These observations, together with the 31,000 people living on the island, make Concepcion volcano an important target for volcanological research. My research focuses on the investigation of the stability of the volcano edifice of Concepcion, using geophysical data such as gravity, geodetic global positioning system (GPS), sulphur dioxide (SO2) flux, real-time seismic amplitude (RSAM), and satellite remotely-sensed data. The integration of these data sets provides information about the short-term behavior of Concepcion, and some insights into the volcano's long-term behavior. This study has provided, for the first time, information about the shallow dynamics of Concepcion on time scales of days to weeks. I furnish evidence that this volcano is not gravitationally spreading in a continuous fashion as previously thought, that its bulk average density is comparable to that of a pile of gravel, that the volcano edifice is composed of two major distinctive lithologies, that the deformation field around the volcano is recoverable in a matter of days, and that the deformation source is located in the shallow crust. This source is also degassing through the relatively open magmatic conduit. There are, however, several remaining questions. Although the volcano is not spreading continuously there is the possibility that gravitational spreading may be taking place in a stick-slip fashion. This has important implications for slope stability of the volcano, and the associated hazards. The factors influencing the long term slope stability of the volcano are still not fully resolved, but internal volcanic processes and anthropogenic disturbances appear to be the major factors.

  9. Cascades Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Driedger, Carolyn; Pallister, John

    2008-01-01

    Washington's Mount St. Helens volcano reawakens explosively on October 1, 2004, after 18 years of quiescence. Scientists at the U.S. Geological Survey's Cascades Volcano Observatory (CVO) study and observe Mount St. Helens and other volcanoes of the Cascade Range in Washington, Oregon, and northern California that hold potential for future eruptions. CVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Mount St. Helens and CVO at http://vulcan.wr.usgs.gov/.

  10. Glaciation of Haleakala volcano, Hawaii

    SciTech Connect

    Moore, J.G.; Mark, R. (Geological Survey, Menlo Park, CA (United States)); Porter, S.C. (Univ. of Washington, Seattle, WA (United States). Quaternary Research Center)

    1993-04-01

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

  11. Penguin Bank: A Loa-Trend Hawaiian Volcano

    NASA Astrophysics Data System (ADS)

    Xu, G.; Blichert-Toft, J.; Clague, D. A.; Cousens, B.; Frey, F. A.; Moore, J. G.

    2007-12-01

    Hawaiian volcanoes along the Hawaiian Ridge from Molokai Island in the northwest to the Big Island in the southeast, define two parallel trends of volcanoes known as the Loa and Kea spatial trends. In general, lavas erupted along these two trends have distinctive geochemical characteristics that have been used to define the spatial distribution of geochemical heterogeneities in the Hawaiian plume (e.g., Abouchami et al., 2005). These geochemical differences are well established for the volcanoes forming the Big Island. The longevity of the Loa- Kea geochemical differences can be assessed by studying East and West Molokai volcanoes and Penguin Bank which form a volcanic ridge perpendicular to the Loa and Kea spatial trends. Previously we showed that East Molokai volcano (~1.5 Ma) is exclusively Kea-like and that West Molokai volcano (~1.8 Ma) includes lavas that are both Loa- and Kea-like (Xu et al., 2005 and 2007).The submarine Penguin Bank (~2.2 Ma), probably an independent volcano constructed west of West Molokai volcano, should be dominantly Loa-like if the systematic Loa and Kea geochemical differences were present at ~2.2 Ma. We have studied 20 samples from Penguin Bank including both submarine and subaerially-erupted lavas recovered by dive and dredging. All lavas are tholeiitic basalt representing shield-stage lavas. Trace element ratios, such as Sr/Nb and Zr/Nb, and isotopic ratios of Sr and Nd clearly are Loa-like. On an ?Nd-?Hf plot, Penguin Bank lavas fall within the field defined by Mauna Loa lavas. Pb isotopic data lie near the Loa-Kea boundary line defined by Abouchami et al. (2005). In conclusion, we find that from NE to SW, i.e., perpendicular to the Loa and Kea spatial trend, there is a shift from Kea-like East Molokai lavas to Loa-like Penguin Bank lavas with the intermediate West Molokai volcano having lavas with both Loa- and Kea-like geochemical features. Therefore, the Loa and Kea geochemical dichotomy exhibited by Big Island volcanoes existed at ~2.2 Ma when the Molokai Island volcanoes formed and has persisted until the present. References: Abouchami et al., 2005 Nature, 434:851-856 Xu et al., 2005 G3, doi: 10.1029/2004GC000830 Xu et al., 2007 G3, doi: 10.1029/2006GC001554

  12. 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.

  13. Volcano seismology

    USGS Publications Warehouse

    Chouet, B.

    2003-01-01

    A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with wide dynamic range, and development of new powerful analysis techniques, rapid progress is being made toward a synthesis of high-quality seismic data to develop a coherent model of eruption mechanics. Examples of recent advances are: (1) high-resolution tomography to image subsurface volcanic structures at scales of a few hundred meters; (2) use of small-aperture seismic antennas to map the spatio-temporal properties of long-period (LP) seismicity; (3) moment tensor inversions of very-long-period (VLP) data to derive the source geometry and mass-transport budget of magmatic fluids; (4) spectral analyses of LP events to determine the acoustic properties of magmatic and associated hydrothermal fluids; and (5) experimental modeling of the source dynamics of volcanic tremor. These promising advances provide new insights into the mechanical properties of volcanic fluids and subvolcanic mass-transport dynamics. As new seismic methods refine our understanding of seismic sources, and geochemical methods better constrain mass balance and magma behavior, we face new challenges in elucidating the physico-chemical processes that cause volcanic unrest and its seismic and gas-discharge manifestations. Much work remains to be done toward a synthesis of seismological, geochemical, and petrological observations into an integrated model of volcanic behavior. Future important goals must include: (1) interpreting the key types of magma movement, degassing and boiling events that produce characteristic seismic phenomena; (2) characterizing multiphase fluids in subvolcanic regimes and determining their physical and chemical properties; and (3) quantitatively understanding multiphase fluid flow behavior under dynamic volcanic conditions. To realize these goals, not only must we learn how to translate seismic observations into quantitative information about fluid dynamics, but we also must determine the underlying physics that governs vesiculation, fragmentation, and the collapse of bubble-rich suspensions to form separate melt and vapor. Refined understanding of such processes-essential for quantitative short-term eruption forecasts-will require multidisciplinary research involving detailed field measurements, laboratory experiments, and numerical modeling.

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

    USGS Publications Warehouse

    Ewert, J.W.

    2007-01-01

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

  15. History of earthquakes and tsunamis along the eastern Aleutian-Alaska megathrust, with implications for tsunami hazards in the California Continental Borderland

    USGS Publications Warehouse

    Ryan, Holly F.; von Huene, Roland; Wells, Ray E.; Scholl, David W.; Kirby, Stephen; Draut, Amy E.

    2012-01-01

    During the past several years, devastating tsunamis were generated along subduction zones in Indonesia, Chile, and most recently Japan. Both the Chile and Japan tsunamis traveled across the Pacific Ocean and caused localized damage at several coastal areas in California. The question remains as to whether coastal California, in particular the California Continental Borderland, is vulnerable to more extensive damage from a far-field tsunami sourced along a Pacific subduction zone. Assuming that the coast of California is at risk from a far-field tsunami, its coastline is most exposed to a trans-Pacific tsunami generated along the eastern Aleutian-Alaska subduction zone. We present the background geologic constraints that could control a possible giant (Mw ~9) earthquake sourced along the eastern Aleutian-Alaska megathrust. Previous great earthquakes (Mw ~8) in 1788, 1938, and 1946 ruptured single segments of the eastern Aleutian-Alaska megathrust. However, in order to generate a giant earthquake, it is necessary to rupture through multiple segments of the megathrust. Potential barriers to a throughgoing rupture, such as high-relief fracture zones or ridges, are absent on the subducting Pacific Plate between the Fox and Semidi Islands. Possible asperities (areas on the megathrust that are locked and therefore subject to infrequent but large slip) are identified by patches of high moment release observed in the historical earthquake record, geodetic studies, and the location of forearc basin gravity lows. Global Positioning System (GPS) data indicate that some areas of the eastern Aleutian-Alaska megathrust, such as that beneath Sanak Island, are weakly coupled. We suggest that although these areas will have reduced slip during a giant earthquake, they are not really large enough to form a barrier to rupture. A key aspect in defining an earthquake source for tsunami generation is determining the possibility of significant slip on the updip end of the megathrust near the trench. Large slip on the updip part of the eastern Aleutian-Alaska megathrust is a viable possibility owing to the small frontal accretionary prism and the presence of arc basement relatively close to the trench along most of the megathrust.

  16. Lifetime of an ocean island volcano feeder zone: constraints from U-Pb dating on coexisting zircon and baddeleyite, and 40/39Ar age determinations, Fuerteventura, Canary Islands

    USGS Publications Warehouse

    Allibon, James; Ovtcharova, Maria; Bussy, Francois; Cosca, Michael; Schaltegger, Urs; Bussien, Denise; Lewin, Eric

    2011-01-01

    High-precision isotope dilution - thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon and baddeleyite ages from the PX1 vertically layered mafic intrusion Fuerteventura, Canary Islands, indicate initiation of magma crystallization at 22.10 ± 0.07 Ma. The magmatic activity lasted a minimum of 0.52 Ma. 40Ar/39Ar amphibole dating yielded ages from 21.9 ± 0.6 to 21.8 ± 0.3, identical within errors to the U-Pb ages, despite the expected 1% theoretical bias between 40Ar/39Ar and U-Pb dates. This overlap could result from (i) rapid cooling of the intrusion (i.e., less than the 0.3 to 0.6 Ma 40Ar/39Ar age uncertainties) from closure temperatures (Tc) of zircon (699-988 °C) to amphibole (500-600 °C); (ii) lead loss affecting the youngest zircons; or (iii) excess argon shifting the plateau ages towards older values. The combination of the 40Ar/39Ar and U/Pb datasets implies that the maximum amount of time PX1 intrusion took to cool below amphibole Tc is 0.8 Ma, suggesting PX1 lifetime of 520,000 to 800,000 Ma. Age disparities among coexisting baddeleyite and zircon (22.10 ± 0.07/0.08/0.15 Ma and 21.58 ± 0.15/0.16/0.31 Ma) in a gabbro sample from the pluton margin suggest complex genetic relationships between phases. Baddeleyite is found preserved in plagioclase cores and crystallized early from low silica activity magma. Zircon crystallized later in a higher silica activity environment and is found in secondary scapolite and is found close to calcite veins, in secondary scapolite that recrystallised from plagioclase. close to calcite veins. Oxygen isotope ?18O values of altered plagioclase are high (+7.7), indicating interaction with fluids derived from host-rock carbonatites. The coexistence of baddeleyite and zircon is ascribed to interaction of the PX1 gabbro with CO2-rich carbonatite-derived fluids released during contact metamorphism.

  17. Klauea--an Explosive Volcano in Hawai`i U.S. Department of the Interior

    E-print Network

    Torgersen, Christian

    K Kïlauea--an Explosive Volcano in Hawai`i U.S. Department of the Interior U.S. Geological Survey USGS Fact Sheet 2011­3064 July 2011 Kïlauea Volcano, on the Island of Hawai`i, is best known for its.S. Geological Survey's (USGS) Hawaiian Volcano Observatory (HVO) 1.8 km (1.1 mile) away, opened in the floor

  18. 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.…

  19. On the carcinogenic polycyclic aromatic hydrocarbon benzo(a)pyrene in volcano exhausts.

    PubMed

    Ilnitsky, A P; Belitsky, G A; Shabad, L M

    1976-05-01

    The content of benzo(a)pyrene in the juvenile ashes of the volcano Tyatya (Kunashir Island, Kuriles) and in the soil, vegetation and volcanic mud collected near volcanos in Kamchatka was studied. It was concluded that volcanic activity does not play a large role in forming the background level of this carcinogen in the human environment. PMID:1016954

  20. Prototype PBO Instrumentation of CALIPSO Project Captures World-Record Lava Dome Collapse on Montserrat Volcano

    Microsoft Academic Search

    Glen S. Mattioli; Simon R. Young; Barry Voight; R. Steven J. Sparks; Eylon Shalev; Sacks Selwyn; Peter Malin; Alan Linde; William Johnston; Dannie Hadayat; Derek Elsworth; Peter Dunkley; Richard Herd; Jurgen Neuberg; Gillian Norton; Christina Widiwijayanti

    2004-01-01

    This article is an update on the status of an innovative new project designed to enhance generally our understanding of andesitic volcano eruption dynamics and, specifically, the monitoring and scientific infrastructure at the active Soufriàre Hills Volcano (SHV), Montserrat. The project has been designated as the Caribbean Andesite Lava Island Precision Seismo-geodetic Observatory, known as CALIPSO. Its purpose is to

  1. Mt. Erebus: A Surprising Volcano: Grades K-1: text only version

    NSDL National Science Digital Library

    Jessica Fries-Gaither

    This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. The reading level is at Kindergarten through grade one. This is a PDF containing the informational text and a glossary.

  2. Mt. Erebus: A Surprising Volcano: Grades 2-3: text only version

    NSDL National Science Digital Library

    Jessica Fries-Gaither

    This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. The text is written at a grade two through grade three reading level. This is a PDF containing the informational text and a glossary.

  3. On the interaction of Tropical Cyclone Flossie and emissions from Hawaii's Kilauea volcano

    E-print Network

    Businger, Steven

    interaction between an active, vigorously degassing volcano and a tropical cyclone captured by a vog (volcanic into a tropical cyclone. Results from the vog dispersion model are compared with Geostationary Operational the dispersion of emissions (vog) from Kilauea volcano across the island of Hawai`i and the other main Hawaiian

  4. Pb, Hf and Nd isotope compositions of the two Runion volcanoes (Indian Ocean): A tale of two small-scale mantle "blobs"?

    E-print Network

    Demouchy, Sylvie

    Pb, Hf and Nd isotope compositions of the two Réunion volcanoes (Indian Ocean): A tale of two small of basaltic lavas from the two Réunion Island volcanoes are reported in order to examine the origin of the sources feeding these volcanoes and to detect possible changes through time. Samples, chosen to cover

  5. Bald eagles and sea otters in the Aleutian Archipelago: indirect effects of trophic cascades.

    USGS Publications Warehouse

    Anthony, R.G.; Estes, J.A.; Ricca, M.A.; Miles, A.K.; Forsman, E.D.

    2008-01-01

    Because sea otters (Enhydra lutris) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles (Haliaeetus leucocephalus) in the Aleutian Islands, Alaska, USA. We studied the diets, productivity, and density of breeding Bald Eagles on four islands during 1993-1994 and 2000-2002, when sea otters were abundant and scarce, respectively. Bald Eagles depend on nearshore marine communities for most of their prey in this ecosystem, so we predicted that the recent decline in otter populations would have an indirect negative effect on diets and demography of Bald Eagles. Contrary to our predictions, we found no effects on density of breeding pairs on four islands from 1993-1994 to 2000-2002. In contrast, diets and diet diversity of Bald Eagles changed considerably between the two time periods, likely reflecting a change in prey availability resulting from the increase and subsequent decline in sea otter populations. The frequency of sea otter pups, rock greenling (Hexagammus lagocephalus), and smooth lumpsuckers (Aptocyclus ventricosus) in the eagle's diet declined with corresponding increases in Rock Ptarmigan (Lagopus mutus), Glaucous-winged Gulls (Larus glaucescens), Atka mackerel (Pleurogrammus monopterygius), and various species of seabirds during the period of the recent otter population decline. Breeding success and productivity of Bald Eagles also increased during this time period, which may be due to the higher nutritional quality of avian prey consumed in later years. Our results provide further evidence of the wide-ranging indirect effects of sea otter predation on nearshore marine communities and another apex predator, the Bald Eagle. Although the indirect effects of sea otters are widely known, this example is unique because the food-web pathway transcended five species and several trophic levels in linking one apex predator to another.

  6. Infrasound Observations of the Recent Explosive Eruptions of Okmok and Kasatochi Volcanoes, Alaska

    NASA Astrophysics Data System (ADS)

    Arnoult, K. M.; Olson, J. V.; Szuberla, C. A.; Garces, M.; Fee, D.; McNutt, S. R.; Hedlin, M. A.

    2008-12-01

    Infrasonic signals produced by the 2008 eruptions of Okmok and Kasatochi volcanoes, Alaska, demonstrated the potential for acoustic remote sensing of eruptions that may pose a hazard to aviation. During its recent period of eruptive activity, Kasatochi Volcano produced at least five explosive eruptions that were recorded by seismometers and infrasound arrays. These eruptions ejected significant ash into the stratosphere and caused numerous flight delays and cancellations. Seismometers located along the Aleutian Islands recorded explosive episodes with start times of 22:01 UT on 7 August 2008, and 01:50, 04:35, 07:12, and 11:48 UT on 8 August 2008. Infrasound arrays located in Fairbanks, Alaska (I53US, 2104 km from Kasatochi), and in Kona, Hawaii (I59US, 3996 km from Kasatochi) also recorded these explosions at times consistent with the seismic observations. The volcanic signals recorded by I53US and I59US had high signal to noise ratios and reached pressure levels of 2.0 Pa peak-to-peak at both arrays during the second explosive eruption. A single infrasound microphone located on Mt. Shishaldin (818 km from Kasatochi) recorded the onsets of explosions 1, 4, and 5 at approximately the times expected; however, due to technical problems, it did not record explosions 2 and 3. Based on seismic observations, the durations of the five explosive eruptions were approximately 68, 27, 35, 46, and 26 minutes, respectively. The corresponding coherent signal durations recorded by the I53US and I59US infrasound arrays were considerably longer: 104, 48, 39, 118, and 31 minutes for I53US and 155, 101, 81, 114, and 187 minutes for I59US. The eruptive events of Okmok Volcano that occurred 12-13 Jul 2008 were also recorded by infrasound arrays I53US and I59US. Although a large ash cloud was produced by Okmok Volcano, the pressure levels of the Okmok infrasound signals, relative to those from Kasatochi, were much less (< 0.5 Pa peak-to-peak at I53US). Three groups of infrasound signals were observed at I53US with arrival times of 21:44 UT on 12 July 2008, and 01:14 and 05:41 UT on 13 July 2008. Their durations were 43, 95, and 29 minutes, respectively. The data from other IMS infrasound arrays will be used to study source and propagation effects. Of particularly interest will be the data from I56US in Newport, Washington (4060 km from Kasatochi, 3547 km from Okmok) and I57US in Pinon Flat, California (5067 km from Kasatochi, 4585 km from Okmok). The relationships between the infrasound signals and the physical characteristics of the ash injections will be investigated.

  7. A Synoptic Analysis of the interannual variability of Winter Cyclone Activity in the Aleutian Low Region

    E-print Network

    Williams, Justin

    . Introduction During the winter season in the North Pacific the dominant feature of the mean circulation associated with years of strong and weak Aleutian Low in the North Pacific is presented. From 1958-2004, ten in the eastern and western portions of the Aleutian Low center influence the heat exchange between the polar

  8. Time-varying deformation recorded by continuous GPS networks on Taal Volcano, Philippines

    Microsoft Academic Search

    B. A. Bartel; M. W. Hamburger; C. M. Meertens; E. Corpuz; E. Gabinete; A. R. Lowry

    2001-01-01

    Continuous GPS measurements of crustal deformation at Taal Volcano, Philippines provide new constraints on ongoing volcanic and hydrothermal activity. Taal is an historically active basaltic-andesitic stratovolcano which forms an island (Volcano Island) within a large (25x30 km), geologically recent, lake-filled caldera. Taal's most recent eruptive sequence, from 1965-1977, included violent phreatomagmatic eruptions accompanied by base surges, basaltic lava flows, and

  9. Deformation interplay at Hawaii Island

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Walter, T. R.

    2009-12-01

    Volcanoes are known to be closely related to the tectonic environment, including vent locations and eruptions resulting from faults and earthquakes. Similarly, adjacent volcanoes interact with each other in time and space, as suggested for the Hawaiian volcanoes Kilauea and Mauna Loa. New satellite radar data imply even more complex deformation interplay in Hawaii than previously thought, involving magma chamber pressure changes, dike intrusions, slow earthquakes and ground subsidence. The affected regions are the Mauna Loa and Kilauea volcano summits, their active rift zones, the island’s unstable southeast flank and even the capital city of Hilo. Based on the data acquired by the European satellite ENVISAT, we present in this work a five-year spatio-temporal analysis of the deformation signals recorded between 2003 and 2008. The data suggests that most of the deformation sources are acting in chorus. The magma intrusion at the Mauna Loa chamber and the intrusion into the Kilauea rift dike are correlated in time while also interacting with gravity-driven flank movement events. Some of the events occur silently underneath the Kilauea south flank, such as slow earthquakes that may largely affect all of the active magmatic systems and reverse their sign of correlation. This study of the interplay between multiple deformations and inherently coupled systems provides a better understanding of Hawaiian volcano activity and may lead to new methods for assessing the hazards that arise during volcano-tectonic activities elsewhere.

  10. Volcanoes: On-Line Edition

    NSDL National Science Digital Library

    This is the on-line version of a general interest publication prepared by the United States Geological Survey (USGS). It provides a general introduction to volcanoes and volcanology. Topics include types of volcanoes; types of eruptions; submarine volcanoes; and features associated with volcanic terrains (geysers, hot springs, etc.). There is also discussion of volcanoes and their association to plate tectonics, extraterrestrial volcanoes, monitoring and research efforts, and the impacts of volcanoes on human populations. A text-only version is also available.

  11. Yellowstone Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Lowenstern, Jacob

    2008-01-01

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

  12. Iceland's Grímsvötn volcano erupts

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-05-01

    About 13 months after Iceland's Eyjafjallajökull volcano began erupting on 14 April 2010, which led to extensive air traffic closures over Europe, Grímsvötn volcano in southeastern took its turn. Iceland's most active volcano, which last erupted in 2004 and lies largely beneath the Vatnajökull ice cap, began its eruption activity on 21 May, with the ash plume initially reaching about 20 kilometers in altitude, according to the Icelandic Meteorological Office. Volcanic ash from Grímsvötn has cancelled hundreds of airplane flights and prompted U.S. president Barack Obama to cut short his visit to Ireland. As Eos went to press, activity at the volcano was beginning to subside.

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

    USGS Publications Warehouse

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

    2010-01-01

    The United States is one of the most volcanically active countries in the world. According to the global volcanism database of the Smithsonian Institution, the United States (including its Commonwealth of the Northern Mariana Islands) is home to about 170 volcanoes that are in an eruptive phase, have erupted in historical time, or have not erupted recently but are young enough (eruptions within the past 10,000 years) to be capable of reawakening. From 1980 through 2008, 30 of these volcanoes erupted, several repeatedly. Volcano monitoring in the United States is carried out by the U.S. Geological Survey (USGS) Volcano Hazards Program, which operates a system of five volcano observatories-Alaska Volcano Observatory (AVO), Cascades Volcano Observatory (CVO), Hawaiian Volcano Observatory (HVO), Long Valley Observatory (LVO), and Yellowstone Volcano Observatory (YVO). The observatories issue public alerts about conditions and hazards at U.S. volcanoes in support of the USGS mandate under P.L. 93-288 (Stafford Act) to provide timely warnings of potential volcanic disasters to the affected populace and civil authorities. To make efficient use of the Nation's scientific resources, the volcano observatories operate in partnership with universities and other governmental agencies through various formal agreements. The Consortium of U.S. Volcano Observatories (CUSVO) was established in 2001 to promote scientific cooperation among the Federal, academic, and State agencies involved in observatory operations. Other groups also contribute to volcano monitoring by sponsoring long-term installation of geophysical instruments at some volcanoes for specific research projects. This report describes a database of information about permanently installed ground-based instruments used by the U.S. volcano observatories to monitor volcanic activity (unrest and eruptions). The purposes of this Volcano-Monitoring Instrumentation Database (VMID) are to (1) document the Nation's existing, ground-based, volcano-monitoring capabilities, (2) answer queries within a geospatial framework about the nature of the instrumentation, and (3) provide a benchmark for planning future monitoring improvements. The VMID is not an archive of the data collected by monitoring instruments, nor is it intended to keep track of whether a station is temporarily unavailable due to telemetry or equipment problems. Instead, it is a compilation of basic information about each instrument such as location, type, and sponsoring agency. Typically, instruments installed expressly for volcano monitoring are emplaced within about 20 kilometers (km) of a volcanic center; however, some more distant instruments (as far away as 100 km) can be used under certain circumstances and therefore are included in the database. Not included is information about satellite-based and airborne sensors and temporarily deployed instrument arrays, which also are used for volcano monitoring but do not lend themselves to inclusion in a geospatially organized compilation of sensor networks. This Open-File Report is provided in two parts: (1) an Excel spreadsheet (http://pubs.usgs.gov/of/2009/1165/) containing the version of the Volcano-Monitoring Instrumentation Database current through 31 December 2008 and (2) this text (in Adobe PDF format), which serves as metadata for the VMID. The disclaimer for the VMID is in appendix 1 of the text. Updated versions of the VMID will be posted on the Web sites of the Consortium of U.S. Volcano Observatories (http://www.cusvo.org/) and the USGS Volcano Hazards Program http://volcanoes.usgs.gov/activity/data/index.php.

  14. Alaska Volcano Observatory Monitoring Station

    USGS Multimedia Gallery

    An Alaska Volcano Observatory Monitoring station with Peulik Volcano behind. This is the main repeater for the Peulik monitoring network located on Whale Mountain, Beecharaof National Wildlife Refuge....

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

    USGS Publications Warehouse

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

    2006-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

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

  17. Volcano Resources for Educators

    NSDL National Science Digital Library

    This site provides an up-to-date list of textual and video educational materials pertaining to volcanoes. The online pamphlets and books, hardcopy books, rental films and videos cover all levels of interest regarding volcanoes. The site furnishes the information or links to information needed to obtain these materials.

  18. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

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

  19. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

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

  20. Chaiten Volcano Still Active

    NSDL National Science Digital Library

    This Boston Globe news article shows 12 stunning pictures of the Chaiten Volcano erupting in Chile, its first activity in over 9,000 years. The most recent eruptive phase of the volcano began on May 2, 2008, and is ongoing. The site also has a blog of open, public commentary.