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Sample records for volcano solomon islands

  1. 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.

  2. Oloketa Tingting Fo Apem Education Long Solomon Islands: Issues in Solomon Islands Education

    ERIC Educational Resources Information Center

    Alcorn, Noeline

    2010-01-01

    This book makes available to a wider audience for the first time material based on fieldwork carried out by the Solomon Island researchers in their own country. The findings will have vital relevance to policy makers, teachers and students. Over the past four years the School of Education, Solomon Islands College of Higher Education and the…

  3. Oloketa Tingting Fo Apem Education Long Solomon Islands: Issues in Solomon Islands Education

    ERIC Educational Resources Information Center

    Alcorn, Noeline

    2010-01-01

    This book makes available to a wider audience for the first time material based on fieldwork carried out by the Solomon Island researchers in their own country. The findings will have vital relevance to policy makers, teachers and students. Over the past four years the School of Education, Solomon Islands College of Higher Education and the

  4. Ciguatera fish poisoning in the Solomon Islands.

    PubMed

    Oreihaka, E

    1992-01-01

    Ciguatera fish poisoning may have existed in the Solomon Islands long ago though there has never been any ciguatera fish poisoning tests been carried to confirm its presence. Suspected occurrences are infrequent and seasonal. Most cases of ciguatera fish poisoning are undocumented that when cases do occur they depend largely on traditional-knowledge and anecdotal information. Areas suspected to have ciguatoxic poisoning problem in the Solomon Islands includes Santa Cruz, Rennell and Bellona, Indispensable reefs, Ontong Java and Wagina island. Fish species considered ciguatoxic includes red emperor, red snapper, roundfaced batfish, barracuda and blue lined sea-bream. In any way ciguatera fish poisoning is as yet not a big health problem in the Solomon Islands. PMID:1340336

  5. Magnitude 8.1 Earthquake off the Solomon Islands

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On April 1, 2007, a magnitude 8.1 earthquake rattled the Solomon Islands, 2,145 kilometers (1,330 miles) northeast of Brisbane, Australia. Centered less than ten kilometers beneath the Earth's surface, the earthquake displaced enough water in the ocean above to trigger a small tsunami. Though officials were still assessing damage to remote island communities on April 3, Reuters reported that the earthquake and the tsunami killed an estimated 22 people and left as many as 5,409 homeless. The most serious damage occurred on the island of Gizo, northwest of the earthquake epicenter, where the tsunami damaged the hospital, schools, and hundreds of houses, said Reuters. This image, captured by the Landsat-7 satellite, shows the location of the earthquake epicenter in relation to the nearest islands in the Solomon Island group. Gizo is beyond the left edge of the image, but its triangular fringing coral reefs are shown in the upper left corner. Though dense rain forest hides volcanic features from view, the very shape of the islands testifies to the geologic activity of the region. The circular Kolombangara Island is the tip of a dormant volcano, and other circular volcanic peaks are visible in the image. The image also shows that the Solomon Islands run on a northwest-southeast axis parallel to the edge of the Pacific plate, the section of the Earth's crust that carries the Pacific Ocean and its islands. The earthquake occurred along the plate boundary, where the Australia/Woodlark/Solomon Sea plates slide beneath the denser Pacific plate. Friction between the sinking (subducting) plates and the overriding Pacific plate led to the large earthquake on April 1, said the United States Geological Survey (USGS) summary of the earthquake. Large earthquakes are common in the region, though the section of the plate that produced the April 1 earthquake had not caused any quakes of magnitude 7 or larger since the early 20th century, said the USGS.

  6. The Solomon Islands Project: an introduction.

    PubMed

    Friedlaender, J S

    1990-04-01

    The twin themes of the Solomon Islands Biomedical Project remain 1) the remarkable genetic heterogeneity of the groups in the Solomons; and 2) the differential responses to these groups to rapid modernization/acculturation over the past two decades of this long term study. This introduction summarizes the historical and ethnic relationships of the survey groups, their established genetic distances and their rankings with regard to acculturation at the times of their first survey, and changes occurring up to 1985-86. Relevant features of diet, life style, and epidemiology are described. PMID:2333935

  7. Vernacular Literacy in the Touo Language of the Solomon Islands

    ERIC Educational Resources Information Center

    Dunn, Michael

    2005-01-01

    The Touo language is a non-Austronesian language spoken on Rendova Island (Western Province, Solomon Islands). First language speakers of Touo are typically multilingual, and are likely to speak other (Austronesian) vernaculars, as well as Solomon Island Pijin and English. There is no institutional support of literacy in Touo: schools function in…

  8. Solomon Islands School Leaders Readiness for Inclusive Education

    ERIC Educational Resources Information Center

    Porakari, James; Sevala, Brenda; Miniti, Patrick; Saemane, George; Sharma, Umesh; Forlin, Chris

    2015-01-01

    The inclusion of students with disabilities was initiated by the Ministry of Education and Human Resource Development in the Solomon Islands in 2013. This paper investigates the knowledge, skills, and values of school leaders in public and private schools in Honiara, the capital of the Solomon Islands, in regard to providing support for inclusive

  9. Facial scarification and tattooing on Santa Catalina Island (Solomon Islands).

    PubMed

    Mammen, L; Norton, S A

    1997-10-01

    Ritual scarification is the culturally sanctioned process of incising the skin to achieve patterned scars. Scarification was practiced widely by traditional societies, but the encroachment of Western cultural expectations has made the practice increasingly uncommon. Ritual tattooing has a meaningful place in many traditional societies. Ritual scarification and tattooing are still found on Santa Catalina Island, an isolated member of the Solomon Islands in the south-west Pacific. PMID:9347234

  10. Mental health services in the Solomon Islands.

    PubMed

    Orotaloa, Paul; Blignault, Ilse

    2012-06-01

    The Solomon Islands comprise an archipelago of nearly 1,000 islands and coral atolls and have an estimated population of 549,574 people. Formal mental health services date back to 1950 when an asylum was established. Since then the process of mental health service development has been largely one of incremental change, with a major boost to community services in the last two decades. During the 1990s a mental health outpatient clinic was established in Honiara, together with attempts to recruit nursing staff as psychiatric coordinators in the provinces. In 1996, the Ministry commenced sending registered nurses for psychiatric training in Papua New Guinea. By 2010, there were 13 psychiatric nurses and one psychiatrist, with a second psychiatrist in training. A National Mental Health Policy was drafted in 2009 but is yet to be endorsed by Cabinet. A significant portion of the population still turns to traditional healers or church leaders for purposes of healing, seeking help from Western medicine only after all other alternatives in the community have been exhausted. There is still a long way to go before mental health services are available, affordable and accessible to the whole population, including people living in geographically remote areas. Realization of this vision requires increased resourcing for mental health services; improved communication and collaboration between the centrally-based, national mental health services and the provincial health services; and closer, ongoing relationships between all stakeholders and partners, both locally and internationally. PMID:26767360

  11. Reunion Island Volcano Erupts

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  12. Anatahan Volcano, Mariana Islands

    NASA Technical Reports Server (NTRS)

    2008-01-01

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

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

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

  13. Aid for Education in Post-Conflict Solomon Islands

    ERIC Educational Resources Information Center

    Whalan, Jeni

    2011-01-01

    Between 1998 and 2003, conflict, violent crime, and a severe economic downturn pushed the Solomon Islands state to the brink of failure, exacerbating the problems of an already struggling education sector. Most schools on Guadalcanal were seriously disrupted; some were burned down or vandalized, others closed as teachers and students fled

  14. Haemophilus ducreyi Associated with Skin Ulcers among Children, Solomon Islands

    PubMed Central

    Chi, Kai-Hua; Vahi, Ventis; Pillay, Allan; Sokana, Oliver; Pavluck, Alex; Mabey, David C.; Chen, Cheng Y.; Solomon, Anthony W.

    2014-01-01

    During a survey of yaws prevalence in the Solomon Islands, we collected samples from skin ulcers of 41 children. Using PCR, we identified Haemophilus ducreyi infection in 13 (32%) children. PCR-positive and PCR-negative ulcers were phenotypically indistinguishable. Emergence of H. ducreyi as a cause of nongenital ulcers may affect the World Health Organization’s yaws eradication program. PMID:25271477

  15. Aid for Education in Post-Conflict Solomon Islands

    ERIC Educational Resources Information Center

    Whalan, Jeni

    2011-01-01

    Between 1998 and 2003, conflict, violent crime, and a severe economic downturn pushed the Solomon Islands state to the brink of failure, exacerbating the problems of an already struggling education sector. Most schools on Guadalcanal were seriously disrupted; some were burned down or vandalized, others closed as teachers and students fled…

  16. Iumi Lanem Pijin. A Basic Course in Solomon Islands Pidgin.

    ERIC Educational Resources Information Center

    Labu, Francis, Ed.; Marshall, Ann C., Ed.

    A set of instructional materials for introductory Solomon Islands Pidgin, an English-based pidgin, is designed for Peace Corps volunteer language instruction. It consists of 12 units that contain dialogues, grammar and pronunciation notes, pattern and substitution drills, lists of vocabulary and useful expressions, and exercises based on the

  17. Amendment to the Solomon Islands National Provident Fund Act.

    PubMed

    1989-01-01

    On 6 June 1988 the Solomon Islands National Provident Fund Act was amended to allow the Solomon Islands National Provident Fund Board to grant loans to members of the Fund. In November 1989 under authority of this amendment the Board implemented a housing scheme for members of the Fund. It instituted loans for the purchase of residential homes from property owners, the construction of residential houses, and the redemption of bank loans obtained for purchase or construction of residential houses. To qualify for the loan the applicant must be a permanent employee, be an active member of the Fund, and less than 50 years old, and the house sought to be purchased or built must be on registered land. PMID:12344585

  18. Remuneration disparities in Oceania: Papua New Guinea and Solomon Islands.

    PubMed

    Marai, Leo; Kewibu, Vincent; Kinkin, Elly; Peter Peniop, John; Salini, Christian; Kofana, Genesis

    2010-10-01

    This paper explores the impact of remuneration differences on workers in the Solomon Islands and Papua New Guinea. In these countries remunerative differences are linked to government policy (in Papua New Guinea) and job contracts (in the Solomon Islands), and have impacted on industrial relations in both settings (strike action). A total of N = 350 professionals (n = 60 expatriates) from 54 organizations in aid, government, higher education and industry (mean response rate = 36%) responded to an organizational survey form. Remuneration ratios between international and local respondents based on the World Bank's index of purchasing power parity approached 9:1. In both sites staff compared pay and benefits (remuneration) packages: Internationally remunerated staff rated their ability higher than their local counterparts did; locally remunerated groups reported more injustice in remuneration, were more demotivated by the gaps, and were more likely to be thinking about leaving the organization. In-country workshops of N = 40 largely local stakeholders from aid and community organizations plus government ministries considered the survey's findings and recommended: in Solomon Islands, (a) introducing a policy of localization, (b) establishing a remuneration commission (already existent in Papua New Guinea), and (c) reducing the remunerative gap; in Papua New Guinea, (d) reversing the post-Independence "dual pay system" (currently official policy), (e) instituting pay-for-performance, and (f) ensuring the existent localization policy is applied to recruitment, selection, and staff career planning and management. PMID:22044056

  19. Tsunami awareness saves Solomon Islanders on 1 April 2007

    NASA Astrophysics Data System (ADS)

    Fritz, H. M.; Kalligeris, N.

    2007-12-01

    On April 1, 2007 at 20:39:56 UTC (local time: UTC+11), a magnitude Ms 8.1 earthquake occurred 50 km off the New Georgia Islands in the Solomon Sea generating a locally focused tsunami striking more than 300 coastal communities in the Solomon Islands. A reconnaissance team deployed within one week investigated 65 coastal settlements on 13 remote Islands and measured run-up heights of 12 m, local flow depths of 5 m as well as tectonic uplift up to 3.6 m and subsidence down to -1.5m. This South Pacific archipelago's worst disaster since WWII resulted in 52 confirmed death and 36'000 directly affected - roughly half of these numbers are children. The ground shaking pinned people to the ground and palm trees bounced back and forth with leafs touching the ground. The ancestral heritage "run to high ground after an earthquake" passed on to younger generations by survivors of a smaller 1952 tsunami triggered an immediate spontaneous self evacuation, which dramatically reduced the death toll in the small evacuation window of a few minutes between the end of the ground shaking and the onslaught of the tsunami. The survivors remained traumatized by the tsunami, afraid of the sea and living in evacuation camps on the hills illustrating the importance of community-based education and awareness programs.

  20. Pig production in the Solomon Islands. I. Village pig production.

    PubMed

    de Fredrick, D F

    1977-05-01

    In 181 villages in the Solomon Islands the pig: human ratio was 1:5-8 and the annual per capita pork consumption was 4-2 kg. Some communities did not keep pigs or eat pig meat. Sows weaned an average of 5-5 piglets per year and mean liveweight at 12 months of age was 28-4 kg. Most pigs were kept on the ground but some were housed in pens over the sea and very few lived in their owner's houses. Pigs were important in the social life of the people but proportionally fewer pigs were raised than in neighbouring Pacific countries. PMID:906090

  1. The Education Pacific Islands Children Deserve: The Learn and Play Project in the Solomon Islands

    ERIC Educational Resources Information Center

    Maebuta, Jack

    2011-01-01

    The Learn and Play Project was initiated by Solomon Islands Football Federation and aimed at educating and providing football skills training for primary school dropouts. The aim of this paper is to report the implementation of the programme in a case study school. Because the project is still being implemented, this paper is not intended to

  2. The Education Pacific Islands Children Deserve: The Learn and Play Project in the Solomon Islands

    ERIC Educational Resources Information Center

    Maebuta, Jack

    2011-01-01

    The Learn and Play Project was initiated by Solomon Islands Football Federation and aimed at educating and providing football skills training for primary school dropouts. The aim of this paper is to report the implementation of the programme in a case study school. Because the project is still being implemented, this paper is not intended to…

  3. He and Sr isotopic constraints on subduction contributions to Woodlark Basin volcanism, Solomon Islands

    SciTech Connect

    Trull, T.W.; Kurz, M.D. ); Perfit, M.R. )

    1990-02-01

    In order to assess the nature and spatial extent of subduction contributions to arc volcanism, Sr and He isotopic compositions are measured for dredged volcanic rocks from the Woodlark Basin in the western Pacific. {sup 87}Sr/{sup 86}Sr ratios increase geographically, from ocean ridge values (.7025-.7029) at the Woodlark Spreading Center to island arc ratios (.7035-.7039) in the Solomon Islands forearc, with intermediate values near the triple junction where the Woodlark Spreading Center subducts beneath the Solomon Islands. {sup 3}He/{sup 4}He ratios are also more radiogenic in the forearc (6.9 {plus minus} .2 R{sub a} at active Kavachi volcano) than along the spreading center, where values typical of major ocean ridges were found (8.2 - 9.3 R{sub a}). Very low {sup 3}He/{sup 4}He ratios occur in many triple junction rocks (.1 to 5 R{sub a}), but consideration of He isotopic differences between crushing and melting analyses suggests that the low ratios were caused by atmospheric (1 R{sub a}) and radiogenic ({approx} 0.2 R{sub a}) helium addition after eruption. Variations in unaltered, magnetic {sup 3}He/{sup 4}He, and {sup 87}Sr/{sup 86}Sr ratios are best explained by subduction-related fluid or silicate melt contributions to the magma source region, perhaps from ancient Pacific lithosphere. However, mantle volatiles dominate the generation of Woodlark Basin rocks despite extensive subduction in the region.

  4. Counting the Cost of Diabetes in the Solomon Islands and Nauru

    PubMed Central

    Win Tin, Si Thu; Iro, George; Gadabu, Eva; Colagiuri, Ruth

    2015-01-01

    Aim To determine the costs associated with diabetes to governments, people with diabetes and their carers, and its impact on quality of life in two Pacific Island countries—the Solomon Islands and Nauru. Materials and Methods This cross-sectional cost of illness study was conducted on 330 people with type 2 diabetes (197 from the Solomon Islands and 133 from Nauru) using a structured cost of illness survey questionnaire adapted from the Australian DiabCo$t study. Quality of life was measured by the EQ-5D Visual Analogue Scale. Results There were 330 respondents (50% female; mean duration of diabetes 10.9 years; mean age 52.6 years). The estimated annual national cost of diabetes incurred by the Solomon Islands government was AUD12.8 million (AUD281 per person/year) and by Nauru government was AUD1.2 million (AUD747 per person/year). The major contribution to the government costs was inpatient services cost (71% in the Solomon Islands and 83% in Nauru). Annual expenditure for diabetes was approximately 20% of the governments’ annual health care expenditure. Considerable absenteeism and retirement from work due to diabetes was found. Conclusions This study found substantial public and personal costs associated with diabetes. The findings provide objective data on which health policy, funding and planning decisions about the prevention and control of diabetes in the Solomon Islands and Nauru can be reliably based and subsequently evaluated. PMID:26698575

  5. Language, Aid and Literacy: An Outline of Activities in the Solomon Islands.

    ERIC Educational Resources Information Center

    Moseley, Lesley

    1994-01-01

    Problems facing the literacy movement in the Solomon Islands are related to communication, economic, and linguistic barriers. The island is linguistically diverse. English is the official language, but a national literacy committee found that only 26% of people could speak English. Improving primary education is a government priority. Training of…

  6. The Solomon Islands tsunami of 6 February 2013 field survey in the Santa Cruz Islands

    NASA Astrophysics Data System (ADS)

    Fritz, H. M.; Papantoniou, A.; Biukoto, L.; Albert, G.

    2013-12-01

    On February 6, 2013 at 01:12:27 UTC (local time: UTC+11), a magnitude Mw 8.0 earthquake occurred 70 km to the west of Ndendo Island (Santa Cruz Island) in the Solomon Islands. The under-thrusting earthquake near a 90° bend, where the Australian plate subducts beneath the Pacific plate generated a locally focused tsunami in the Coral Sea and the South Pacific Ocean. The tsunami claimed the lives of 10 people and injured 15, destroyed 588 houses and partially damaged 478 houses, affecting 4,509 people in 1,066 households corresponding to an estimated 37% of the population of Santa Cruz Island. A multi-disciplinary international tsunami survey team (ITST) was deployed within days of the event to document flow depths, runup heights, inundation distances, sediment and coral boulder depositions, land level changes, damage patterns at various scales, performance of the man-made infrastructure and impact on the natural environment. The 19 to 23 February 2013 ITST covered 30 locations on 4 Islands: Ndendo (Santa Cruz), Tomotu Noi (Lord Howe), Nea Tomotu (Trevanion, Malo) and Tinakula. The reconnaissance completely circling Ndendo and Tinakula logged 240 km by small boat and additionally covered 20 km of Ndendo's hard hit western coastline by vehicle. The collected survey data includes more than 80 tsunami runup and flow depth measurements. The tsunami impact peaked at Manoputi on Ndendo's densely populated west coast with maximum tsunami height exceeding 11 m and local flow depths above ground exceeding 7 m. A fast tide-like positive amplitude of 1 m was recorded at Lata wharf inside Graciosa Bay on Ndendo Island and misleadingly reported in the media as representative tsunami height. The stark contrast between the field observations on exposed coastlines and the Lata tide gauge recording highlights the importance of rapid tsunami reconnaissance surveys. Inundation distance and damage more than 500 m inland were recorded at Lata airport on Ndendo Island. Landslides were observed on volcanic Tinakula Island and on Ndendo Island. Observations from the 2013 Santa Cruz tsunami are compared against the 2007 and 2010 Solomon Islands tsunamis. The team also interviewed eyewitnesses and educated residents about the tsunami hazard in numerous ad hoc presentations and discussions. The combination of ancestral knowledge and recent Solomon Islands wide geohazards education programs triggered an immediate spontaneous self-evacuation containing the death toll in the small evacuation window of few minutes between the end of the ground shaking and the onslaught of the tsunami. Fortunately school children were shown a video on the 1 April 2007 Solomon Islands tsunami 3 months prior to the Santa Cruz event and the headmaster of the school at Venga evacuated the later flooded school already during a foreshock. On Tomotu Noi Island at Bamoi the residents evacuated inland towards a crocodile infested lake, which was not reached by the tsunami inundation. Community-based education and awareness programs are particularly essential to help save lives in locales at risk from near-source tsunamis.

  7. Corals persisting in naturally turbid waters adjacent to a pristine catchment in Solomon Islands.

    PubMed

    Albert, Simon; Fisher, Paul L; Gibbes, Badin; Grinham, Alistair

    2015-05-15

    Few water quality measurements exist from pristine environments, with fewer reported studies of coastal water quality from Solomon Islands. Water quality benchmarks for the Solomons have relied on data from other geographic regions, often from quite different higher latitude developed nations, with large land masses. We present the first data of inshore turbidity and sedimentation rate for a pristine catchment on Isabel Island. Surveys recorded relatively high coral cover. The lowest cover was recorded at 22.7% (Jejevo) despite this site having a mean turbidity (continuous monitoring) of 32 NTU. However, a similar site (Jihro) was significantly less turbid (2.1 mean NTU) over the same period. This difference in turbidity is likely due to natural features of the Jihro River promoting sedimentation before reaching coastal sites. We provide an important baseline for Solomon Island inshore systems, whilst demonstrating the importance of continuous monitoring to capture episodic high turbidity events. PMID:25752531

  8. Prevalence of sexually transmitted infections in female clinic attendees in Honiara, Solomon Islands

    PubMed Central

    Kako, H; Butcher, R; Lauri, B; Puiahi, E; Pitakaka, R; Sokana, O; Kilua, G; Roth, A; Solomon, A W; Mabey, D C

    2015-01-01

    Objectives This study sought to determine the prevalence of common bacterial sexually transmitted infections, including Chlamydia trachomatis and Neisseria gonorrhoeae, in women attending clinics in the Solomon Islands. Methods We conducted a sexual health survey among women attending three nurse-led community outpatient clinics in August 2014, to establish the prevalence of bacterial sexually transmitted infections in female clinic attenders in Honiara, Solomon Islands. Vaginal swab samples were tested for infection with C. trachomatis and N. gonorrhoeae using a commercial strand displacement amplification assay. Serum samples were tested for syphilis. Results We enrolled 296 women, aged 1649, attending three clinics. Knowledge of safe sexual practices was high but reported condom usage was low. The prevalence of infection with C. trachomatis was 20%. The prevalence of infection with N. gonorrhoeae and syphilis were 5.1% and 4.1%, respectively. Conclusions Bacterial sexually transmitted infections are a major health problem in the Solomon Islands. Interventions are urgently needed. PMID:25922103

  9. Family planning: personal and political perspectives from Choiseul Province, Solomon Islands.

    PubMed

    Rowling, D; Hartley, D; Owen, J; Strachan, J

    1995-12-01

    Rapid population growth has put family planning on personal and political agendas in the Solomon Islands. With the release of a population policy in 1988, national leaders sanctioned the concept of family planning as a key strategy in reducing the rate of population growth. On a personal level, Solomon Islanders share their government's concern about population problems. There is a shortage of arable land, health services are stretched, and there are limited places in school for children. A study in Choiseul Province, a rural area in Solomon Islands, suggests that people want smaller families but have limited means to control their fertility. Meagre resources and infrastructure, compounded by geography, climate, culture and religion, constrain the development of family planning services. PMID:8616203

  10. Baseline arsenic levels in marine and terrestrial resources from a pristine environment: Isabel Island, Solomon Islands.

    PubMed

    Grinham, Alistair; Kvennefors, Charlotte; Fisher, Paul L; Gibbes, Badin; Albert, Simon

    2014-11-15

    Baseline records are crucial in understanding how chemicals of concern impact on the receiving environment. We analysed terrestrial and marine resources from a pristine site on Isabel Island, Solomon Islands, to provide environmental baseline levels for total arsenic and arsenic species composition for commonly consumed marine resources. Our data show that levels of the more toxic inorganic arsenic species were very low or below detectable limits, with the exception of the seaweed Sargassum sp. that contained pentavalent inorganic arsenic levels of 4.63 ?g g(-1). Total arsenic concentrations in the majority of marine and terrestrial samples collected were below 2 ?g g(-1). The less toxic arsenobetaine was the predominant arsenic species present in all marine fauna samples analysed. This work highlights the need for arsenic speciation analysis to accurately assess potential toxicity of marine resources and provides a crucial baseline to assess the impact of future development within this region. PMID:25199709

  11. Building on Living Traditions: Early Childhood Education and Culture in Solomon Islands

    ERIC Educational Resources Information Center

    Burton, Lindsay J.

    2012-01-01

    The Solomon Islands, a small developing nation in the South Pacific, demonstrates an emerging community-based kindergarten model with the potential to promote context and culture relevant early learning and development, despite deeply embedded foundations in colonial legacies. Based on the Kahua region of Makira-Ulawa Province, this collaborative,…

  12. Pijin at School in Solomon Islands: Language Ideologies and the Nation

    ERIC Educational Resources Information Center

    Jourdan, Christine

    2013-01-01

    In this article, I analyze the reasons that have excluded Pijin, the lingua franca of Solomon Islands, South West Pacific, from being used as a medium of instruction, and why this may now become possible. Following a short sociolinguistic sketch, I present the colonial and post-colonial linguistic ideologies that shaped sociolinguistic

  13. Influence of Schools on Economically Disadvantageous Attitudes: A Solomon Islands Study

    ERIC Educational Resources Information Center

    MacBeth, Alastair M.

    1976-01-01

    This study examines the economically detrimental attitude of regionalism in a Solomon Islands secondary school and measures changes in regionalism with exposure to school experience that stressed regional integration. Significant decreases in regionalism were recorded. (Available from Plenum Publishing Corporation, 227 West 17 Street, New York, NY

  14. Woodlark Island in Solomon Sea as seen from the Apollo 7 spacecraft

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Woodlark Island in the Solomon Sea, east of New Guinea and northeast of Australia, as seen from the Apollo 7 spacecraft during its 158th revolution of the earth. Photographed from an altitude of 140 nautical miles, at ground elapsed time of 251 hours and 21 minutes.

  15. Technical and Vocational Education and Training in Peace Education: Solomon Islands

    ERIC Educational Resources Information Center

    Maebuta, Jack

    2011-01-01

    Technical and vocational education and training programs as a form of peace education are examined in this paper. It explores the notion of educating for a culture of peace through refocusing technical and vocational education and training programs on sustainable community development in the Solomon Islands. It further highlights the policy and…

  16. Technical and Vocational Education and Training in Peace Education: Solomon Islands

    ERIC Educational Resources Information Center

    Maebuta, Jack

    2011-01-01

    Technical and vocational education and training programs as a form of peace education are examined in this paper. It explores the notion of educating for a culture of peace through refocusing technical and vocational education and training programs on sustainable community development in the Solomon Islands. It further highlights the policy and

  17. "Engendering" environmental projects: the case of eco-timber production in the Solomon Islands.

    PubMed

    Scheyvens, R

    1998-11-01

    This article discusses the case of timber production in the Solomon Islands and links between environmental protection and gender. Many environmental projects are undertaken without regard for gender roles and relations. The Solomon Western Islands Fair Trade (SWIFT) initiative included women in only a peripheral way. This article justifies the involvement of women in environmental projects and then evaluates the operations of SWIFT. A role for women in local environmental projects should be recognized because of women's roles, knowledge, and interests. Use of natural resources is gender-based. In the Solomon Islands, women are identified as having the greater interest in the long-term sustainability of the environment and greater reliance on natural resources to fulfill their roles, but forestry is men's work. The price of tropical woods has tempted Micronesian governments to exploit forests to enhance their foreign exchange earnings. Environmental degradation from logging is particularly severe in the Solomon Islands. The population fulfills many basic needs from forests. Forests can provide cash earnings. The author conducted an evaluation of effectiveness of SWIFT in 1996. The SWIFT project allows rural people to earn cash from sustainable timber extraction without signing with logging companies. Women are affected by SWIFT due to their husbands' appropriation of their earnings, their peripheral role, and lack of representation in senior positions and use of women's forestry expertise. The article offers a model for genderizing eco-projects. Men need to be encouraged to work more as partners with women. PMID:12321992

  18. "We can move forward": challenging historical inequity in public health research in Solomon Islands

    PubMed Central

    2010-01-01

    Background In resource-poor countries, such as Solomon Islands, the research agenda on health is often dominated by researchers from resource-rich countries. New strategies are needed to empower local researchers to set directions for health research. This paper presents a process which seeks to enable a local and potentially more equitable research agenda at a remote hospital in Solomon Islands. Methods In preparation for a health research capacity-building workshop at Atoifi Adventist Hospital, Malaita, Solomon Islands, a computer-based search was conducted of Solomon Islands public health literature. Using a levels-of-agreement approach publications were categorised as: a) original research, b) reviews, c) program descriptions and d) commentaries or discussion. Original research publications were further sub-categorised as: i) measurement, ii) descriptive research and iii) intervention studies. Results were reviewed with Solomon Islander health professionals in a focus group discussion during the health research workshop. Focus group participants were invited to discuss reactions to literature search results and how results might assist current or future local researchers to identify gaps in the published research literature and possible research opportunities at the hospital and surrounding communities. Focus group data were analysed using a grounded theory approach. Results Of the 218 publications meeting inclusion criteria, 144 (66%) were categorised as 'original research', 42 (19%) as 'commentaries/discussion', 28 (13%) as 'descriptions of programs' and 4 (2%) as 'reviews'. Agreement between three authors' (MRM, DM, AC) independent categorisation was 'excellent' (0.8 Solomon Islands (largely non-Solomon Islanders); ii) when the research was done (research needs to keep up to date); iii) amount of published research (there should be more); iv) types of research (lack of intervention and operational research); v) value of published research (important); vi) gaps in published literature (need more research about nursing); vii) opportunities for research action (start small); viii) support required to undertake research at the hospital and in surrounding communities (mentoring and partnering with experienced researchers). Conclusions A search and collaborative review of public health literature for Solomon Islands at a health research capacity building workshop has uncovered and challenged historical inequity in the conduct and access to public health research. Emerging Solomon Islander researchers at a remote hospital are now working to set priorities and strengthen local research efforts. These efforts have highlighted the importance of collaboration and mentoring for Solomon Islanders to instigate and implement public health research to improve the health of individuals and communities served by this remote hospital. PMID:21050492

  19. Molecular analysis of glucose-6-phosphate dehydrogenase variants in the Solomon Islands

    SciTech Connect

    Hirono, A.; Ishii, A.; Hirono, K.; Miwa, S.; Kere, N.; Fujii, H.

    1995-05-01

    Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most prevalent genetic disorders, and >100 million people are considered to have mutant genes. G6PD deficiency is frequent in the area where plasmodium falciparum infection is endemic, probably because the G6PD-deficient subjects are resistant to the parasite. Falciparum and vivax malarias have been highly endemic in the Solomon Islands, and a high frequency of G6PD deficiency has also been expected. A recent investigation showed that the frequency of G6PD deficiency in the Solomon Islands was 8.4%-14.4%. Although >80 G6PD variants from various populations have been molecularly analyzed, little is known about those in Melanesians. G6PD Maewo, which was originally found in Vanuatu, has so far been the only Melanesian variant whose structural abnormality was determined. 14 refs., 1 fig.

  20. Molecular phylogenetics of monarch flycatchers (genus Monarcha) with emphasis on Solomon Island endemics.

    PubMed

    Filardi, Christopher E; Smith, Catherine E

    2005-12-01

    Systematic relationships among monarch flycatchers (genus Monarcha) are poorly understood despite dramatic patterns of morphological differentiation that have long attracted the attention of evolutionary biologists. With sequence data from the mitochondrial ND2 gene and Control Region, we produced a phylogenetic hypothesis for evolutionary relationships within Monarcha and among the biogeographically complex Solomon Island endemics. Outgroup analyses contradicted monophyly of the genus by imbedding a representative of the genus Clytorhynchus within one of two major clades recovered within Monarcha. These two monarch clades generally correspond with ecological and morphological distinctions, suggesting the genus may warrant revision pending the inclusion of taxa currently allied with Clytorhynchus (e.g., Neolalage spp.). Maximum likelihood reconstructions support monophyletic groupings of the two endemic Solomon Island monarch radiations, however, two currently recognized superspecies (Monarcha manadensis and M. melanopsis) were polyphyletic and paraphyletic, respectively. Interestingly, molecular and morphological differentiation were strikingly decoupled among several Solomon Island endemics and between migratory and non-migratory forms of Monarcha trivirgatus in eastern Australia, suggesting morphological evolution has masked the true history of speciation in these groups. This initial phylogeny provides a novel platform for ongoing exploration of the history underlying dramatic patterns of geographic variation among tropical Pacific flycatchers. PMID:16291094

  1. Checklist of the ants (Hymenoptera, Formicidae) of the Solomon Islands and a new survey of Makira Island

    PubMed Central

    Sarnat, Eli M.; Blanchard, Benjamin; Guénard, Benoit; John Fasi;  Evan P. Economo

    2013-01-01

    Abstract The intent of this paper is to facilitate future research of the Solomon Islands ant fauna by providing the first comprehensively researched species inventory in over 75 years. The species list presented here includes the names of all ant species recorded from the islands that are available in the literature together with specimen records from several museum collections and new records from our 2008 Makira field expedition. All the names of described species presented are valid in accordance with the most recent Formicidae classification. In total, the checklist is composed of 237 species and subspecies (including 30 morphospecies) in 59 genera representing nine subfamilies. We report that the recent field expedition added 67 new species records to Makira and 28 new species records to the Solomon Islands. Our research recovered species occurrence records for 32 individual islands and five island groups. The five islands with the highest number of recorded species are: Makira (142 spp.), Guadalcanal (107 spp.), Malaita (70 spp.), Santa Isabel (68 spp.), and Rennell (66 spp.). Based on our results, we discuss the taxonomic composition of the archipelago’s ant fauna, which islands are most in need of additional sampling, and the importance of establishing biodiversity baselines before environmental threats such as the invasive ant Wasmannia auropunctata cause irrevocable harm to the native biodiversity. PMID:23653494

  2. Near-Field Population Response During the 2 April 2007 Solomon Islands Tsunami

    NASA Astrophysics Data System (ADS)

    McAdoo, B. G.; Moore, A. L.; Baumwoll, J.

    2007-12-01

    When the magnitude 8.1 earthquake and subsequent tsunami hit the Solomon Islands on 2 April 2007 it killed 52 people. On Ghizo Island, home of the capital of the Western Province, Gizo, waves approaching 4 m in height inundated the south coast villages. Eyewitness accounts supported by geologic data from the offshore coral reef and sediment deposited on land suggest a wave that came in as the shaking stopped as a rapidly-rising tide rather than a turbulent bore- vehicles and houses were floated inland with very little damage. Those that survived in villages affected by the tsunami had indigenous knowledge of prior events, whereas immigrant populations died in higher proportions. While buoy-based early warning systems are necessary to mitigate the effects of teletsunamis, they would have done little good in this near-field environment. In Pailongge, a village of 76 indigenous Solomon Islanders on Ghizo's south coast, there were no deaths. Village elders directed the people inland following the shaking and the almost immediate withdrawal of water from the lagoon, and heads of household made sure that children were accounted for and evacuated. Of the 366 Gilbertese living in Titiana, however, 13 people died, 8 of which were children who were exploring the emptied lagoon. A large proportion of the dead were children (24) as they were likely too weak to swim against the non-bore flow. The Gilbertese migrated from Kiribati in the 1950"s, and had not experienced a major earthquake and tsunami, hence had no cultural memory. In the case of the Solomon Islands tsunami, as was the case in the 2004 Indian Ocean tsunami, indigenous knowledge served the people in the near-field well. In the case of the Indian Ocean where there was 10-20 minutes separation between the time the shaking began and the waves arrived, the combination of an in-place plan and a suitable physical geography allowed the population of Simeulue Island and the Moken people of Thailand to escape before the waves hit. In the Solomons, there was less than 3 minutes separation time, and the populations with indigenous knowledge were able to save themselves. Mitigation strategies for those that live adjacent to tsunamigenic subduction zones must include a community-based disaster management plan to educate a variety of populations with different cultural knowledges. This education can be in concert with development of an basin-wide early warning system.

  3. Prevalence of soil-transmitted helminths in remote villages in East Kwaio, Solomon Islands

    PubMed Central

    Harrington, Humpress; Bradbury, Richard; Taeka, James; Asugeni, James; Asugeni, Vunivesi; Igeni, Tony; Gwala, John; Newton, Lawrence; Fa, Chillion Evan; Kilivisi, Fawcett Laurence; Esau, Dorothy; Flores, Angelica; Ribeyro, Elmer; Liku, Daisy; Muse, Alwin; Asugeni, Lyndel; Talana, Jeptha; Shield, Jennifer; MacLaren, David J; Massey, Peter D; Muller, Reinhold

    2015-01-01

    Objective Although soil-transmitted helminths (STH) are endemic in Solomon Islands, there are few recent reports on their prevalence. This study aimed to determine the prevalence of STH in residents of remote communities in Solomon Islands. Methods A cross-sectional convenience-sampled survey of residents of four adjacent villages in Malaita, Solomon Islands was performed in Atoifi and Na’au in April 2011 and in Abitona and Sifilo in April 2012. All residents older than one year were invited to participate, which involved providing a single sample of faeces examined using a modified Kato-Katz technique and completing a questionnaire that asked demographic and STH-related behaviour questions. Results The overall participation rate was 52.8%, with 402 participants comprising 49.8% males. Hookworm was the predominant STH with only a single case of trichuriasis found in Atoifi. The total prevalence of hookworm was 22.6% (95% confidence interval: 18.6–27.1); the prevalence of hookworm in Abitona, Na’au and Sifilo was 20.0%, 29.9% and 27.4%, respectively, whereas in Atoifi it was 2.3% (P < 0.001). Intensity was low in all villages. Although health behaviours differed significantly between Atoifi and the other three villages, the type of toilet used was the only significant association with hookworm. Discussion Residents of Atoifi have a relative freedom from STH compared to the other three villages. Rather than a region-wide morbidity control approach, a “one village at a time” approach aiming to eliminate STH and dealing with each village as a separate autonomous unit empowered to manage its own challenges may be a preferred option. PMID:26668767

  4. Health impacts of climate change in the Solomon Islands: an assessment and adaptation action plan.

    PubMed

    Spickett, Jeffery T; Katscherian, Dianne

    2014-09-01

    The Pacific island countries are particularly vulnerable to the environmental changes wrought by global climate change such as sea level rise, more frequent and intense extreme weather events and increasing temperatures. The potential biophysical changes likely to affect these countries have been identified and it is important that consideration be given to the implications of these changes on the health of their citizens. The potential health impacts of climatic changes on the population of the Solomon Islands were assessed through the use of a Health Impact Assessment framework. The process used a collaborative and consultative approach with local experts to identify the impacts to health that could arise from local environmental changes, considered the risks associated with these and proposed appropriate potential adaptive responses. Participants included knowledgeable representatives from the biophysical, socio-economic, infrastructure, environmental diseases and food sectors. The risk assessments considered both the likelihood and consequences of the health impacts occurring using a qualitative process. To mitigate the adverse effects of the health impacts, an extensive range of potential adaptation strategies were developed. The overall process provided an approach that could be used for further assessments as well as an extensive range of responses which could be used by sectors and to assist future decision making associated with the Solomon Islands' responses to climate change. PMID:25168977

  5. Measuring maternal mortality in developing Pacific island countries: experience with the sisterhood method in the Solomon Islands.

    PubMed

    O'Brien, J; Wierzba, T; Knott, S; Pikacha, J

    1994-07-13

    The aim was to estimate the maternal mortality rate in the Solomon Islands and to assist health planning in the implementation of effective interventions. In many Pacific Island countries, registration of deaths is inaccurate and incomplete. The survey in the Solomon Islands was conducted in June 1992, and 2580 randomly chosen women were interviewed using the standard World Health Organization cluster sampling technique. The sisterhood method, an indirect technique for deriving population-based estimates of maternal mortality, was used in interviews reporting on the fertility and mortality experience of subjects' sisters. The sisterhood method was developed at the London School of Hygiene and Tropical Medicine in 1987 as an indirect technique for deriving population-based estimates of maternal mortality. In order to calculate the proportions of sisters dying of maternal causes, 4 questions were asked about deaths of their sisters 15 years of age or over during pregnancy, delivery or the puerperium. These, together with the 5-year age group of the respondents, formed the basic data for deriving an estimate of maternal mortality. An overall estimate of lifetime risk of maternal death across all respondent age groups was derived by dividing the total reported maternal deaths by the sum of the units of risk exposure across all age groups (73/2227 = 0.033) or a lifetime risk of 1 in 30. Through a series of well-defined mathematical calculations, it was possible to convert the information into retrospective estimates of maternal mortality. The maternal mortality ratio in this study was 549/100,000 (95% CI 431, 684), equivalent to 1 maternal death in every 180 pregnancies. The sisterhood method was found to be easy to administer, inexpensive, and quick, and is recommended as a measurement tool to other developing countries. The publication of the results has prompted the government of the Solomon Islands to act. PMID:8022583

  6. Tuberculosis notifications, characteristics and treatment outcomes: urban vs. rural Solomon Islands, 20002011

    PubMed Central

    Hill, P. C.; Bissell, K.; Harries, A. D.; Viney, K.; Gounder, S.

    2014-01-01

    Setting: All provincial tuberculosis (TB) management units in the Solomon Islands. Objective: To compare TB notifications, characteristics and treatment outcomes in urban vs. rural areas. Design: A retrospective descriptive cohort study involving record review and data extraction from provincial TB and laboratory registers and treatment charts from 2000 to 2011. Results: Of 4137 TB cases notified, 1364 (33%) were from urban and 3227 (67%) from rural areas. Notification rates per year of study were consistently higher in urban areas (104150 per 100 000 population) than in rural areas (4970/100 000). Cases in rural areas were more likely to have smear-negative pulmonary TB and less likely to have extra-pulmonary TB (P < 0.001). TB cases in rural areas were more likely to die from TB than those from urban areas (3.2% vs. 5.9%). In contrast, TB cases in rural areas were less likely to default (2.8% vs. 1.8%). Conclusion: TB notification rates were much higher in urban than in rural areas in the Solomon Islands. Rural patients are more likely to die from the disease but are slightly less likely to default. Further research is required to explore the possibility of under-reporting in rural areas and to improve treatment outcomes. PMID:26477283

  7. Mapping the epidemiology of yaws in the Solomon Islands: a cluster randomized survey.

    PubMed

    Marks, Michael; Vahi, Ventis; Sokana, Oliver; Puiahi, Elliot; Pavluck, Alex; Zhang, Zaixing; Dalipanda, Tenneth; Bottomley, Christian; Mabey, David C; Solomon, Anthony W

    2015-01-01

    Yaws, a non-venereal treponemal disease, is targeted for eradication by 2020 but accurate epidemiological data to guide control programs remain sparse. The Solomon Islands reports the second highest number of cases of yaws worldwide. We conducted a cluster randomized survey of yaws in two provinces of the Solomon Islands. One thousand four hundred and ninety-seven (1,497) children 5-14 years of age were examined. Clinical signs of active yaws were found in 79 children (5.5%), whereas 140 children (9.4%) had evidence of healed yaws lesions. Four hundred and seventy (470) (31.4%) children had a positive Treponema pallidum particle agglutination assay (TPPA). Two hundred and eighty-five (285) children (19%) had a positive TPPA and rapid plasma regain assay. Risk of yaws increased with age and was more common in males. The prevalence of yaws at village level was the major risk factor for infection. Our findings suggest the village, not the household, should be the unit of treatment in the World Health Organization (WHO) yaws eradication strategy. PMID:25422395

  8. Mapping the Epidemiology of Yaws in the Solomon Islands: A Cluster Randomized Survey

    PubMed Central

    Marks, Michael; Vahi, Ventis; Sokana, Oliver; Puiahi, Elliot; Pavluck, Alex; Zhang, Zaixing; Dalipanda, Tenneth; Bottomley, Christian; Mabey, David C.; Solomon, Anthony W.

    2015-01-01

    Yaws, a non-venereal treponemal disease, is targeted for eradication by 2020 but accurate epidemiological data to guide control programs remain sparse. The Solomon Islands reports the second highest number of cases of yaws worldwide. We conducted a cluster randomized survey of yaws in two provinces of the Solomon Islands. One thousand four hundred and ninety-seven (1,497) children 5–14 years of age were examined. Clinical signs of active yaws were found in 79 children (5.5%), whereas 140 children (9.4%) had evidence of healed yaws lesions. Four hundred and seventy (470) (31.4%) children had a positive Treponema pallidum particle agglutination assay (TPPA). Two hundred and eighty-five (285) children (19%) had a positive TPPA and rapid plasma regain assay. Risk of yaws increased with age and was more common in males. The prevalence of yaws at village level was the major risk factor for infection. Our findings suggest the village, not the household, should be the unit of treatment in the World Health Organization (WHO) yaws eradication strategy. PMID:25422395

  9. Geologic Survey of the 2 April 2007 Solomon Islands Earthquake and Tsunami

    NASA Astrophysics Data System (ADS)

    Rafiau, W. B.; Jackson, K. L.; Billy, D.; Bonte-Grapentin, M.; Kruger, J.; McAdoo, B. G.; Moore, A. L.; Tiano, B.

    2007-12-01

    The 2 April 2007 magnitude 8.1 Solomon Islands earthquake and tsunami caused extensive damage to coral reefs, coastal erosion, and in some locations, 3 meters of uplift, subsidence, and numerous landslides in the Western and Choiseul Provinces. Extensive damage to the coral reefs ranged from shattered branching corals to 4 meter head corals snapped off their bases and toppled over. The fringing reef on the east coast of Ranongga sustained the greatest degree of damage as it was uplifted 3 m above sea level and remains completely exposed. Sediment samples were collected along transects extended from offshore to onshore environments for larger islands, such as Ghizo, where the tsunami did not pass over the entire island. Smaller islands, such as Nusa Aghana, a transect was conducted from the outer barrier reefs, through the lagoon, across the island, and offshore on the opposing side of the island. Offshore data was collected using a side-scan sonar system that records bathymetry and images coral reef morphology. This data was coupled with snorkeling and SCUBA diving to ground truth the offshore lagoon and reef environments. Sediment samples were collected offshore every 5 m and were documented by underwater photos and GPS coordinates. Offshore to onshore sediment transects reveal that sediment was eroded from seaward facing shorelines, deposited a thin veneer of sediment on islands, and transported the majority of the sediment on coral reefs on the lagoon side of islands, essentially burying coral and lagoonal sediment. Coral reef damaged by the earthquake and tsunami represents a major concern for an already threatened ecosystem. Recovery of the fishing and dive tourism economies rely on the healthy reestablishment of the reef.

  10. Sexual development and reproductive demography of the green humphead parrotfish ( Bolbometopon muricatum) in the Solomon Islands

    NASA Astrophysics Data System (ADS)

    Hamilton, R. J.; Adams, S.; Choat, J. H.

    2008-03-01

    An investigation of the reproductive biology of the green humphead parrotfish ( Bolbometopon muricatum) from three areas in the Western Province of the Solomon Islands revealed that B. muricatum exhibits several features that differ from the pattern of reproductive development observed in most parrotfishes. Unlike most parrotfishes, histological evidence suggests that the sexual pattern of B. muricatum is essentially gonochoristic with high incidences of anatomical but non-functional hermaphroditism. B. muricatum also differs from other parrotfishes in that all males pass through an immature female (or bisexual) phase as demonstrated by all adult testis retaining the ex-ovarian lumen and peripheral sperm sinuses in the gonad wall. However, a protogynous diandric reproductive strategy cannot be excluded given that sampling may have missed transitional individuals. Marked variation in the demography of male B. muricatum between the three locations examined is considered to reflect variation in historical fishing effort.

  11. Marine protected areas and resilience to sedimentation in the Solomon Islands

    NASA Astrophysics Data System (ADS)

    Halpern, B. S.; Selkoe, K. A.; White, C.; Albert, S.; Aswani, S.; Lauer, M.

    2013-03-01

    The ability of marine protected areas (MPAs) to provide protection from indirect stressors, via increased resilience afforded by decreased impact from direct stressors, remains an important and unresolved question about the role MPAs can play in broader conservation and resource management goals. Over a five-year period, we evaluated coral and fish community responses inside and outside three MPAs within the Roviana Lagoon system in Solomon Islands, where sedimentation pressure from upland logging is substantial. We found little evidence that MPAs decrease impact or improve conditions and instead found some potential declines in fish abundance. We also documented modest to high levels of poaching during this period. Where compliance with management is poor, and indirect stressors play a dominant role in determining ecosystem condition, as appears to be the case in Roviana Lagoon, MPAs may provide little management benefit.

  12. A review of health leadership and management capacity in the Solomon Islands.

    PubMed

    Asante, Augustine; Roberts, Graham; Hall, John

    2012-04-01

    ACCESS AND UTILISATION OF HEALTH CARE: The armed conflict that engulfed the Solomon Islands between 1998 and 2003 significantly disrupted the provision of health care especially in rural and remote areas. There is one doctor for 3,300 people and approximately 13 nurses and midwives for 10,000 people. Despite limitations 87% of people seek health care when sick. FINANCING THE HEALTH SYSTEM: The SIG placed a series of reservations on ministerial goods and services budgets that effectively the budget by 33%, severely impacting provincial budgets and resulting in acquired debts. Shortfalls have been addressed by allocating Health Sector Support Program funds to the provinces to allow services to continue, a strategy that will likely recur, but by which donor support replaces government provision Provincial health accountants have received training in MYOB in 2009 but acquittal systems require higher level accounting skills for reports to be submitted on time to permit the release of subsequent funding tranches. HUMAN RESOURCES FOR HEALTH: The shortage of doctors and specialists is a key challenge. As at December 2010, there were a total of 2,728 health workers in the public sector in Solomon Islands. Staff costs consume on average 55% of provincial health grants Filled Public Service Division staff establishments and budgetary reservations have reduced the ability to meet the salary and wage costs of new graduates. Solomon Islands is currently negotiating to assist Vanuatu in filling its nursing staff vacancies with its surplus The return of 75 Cuban trained medical officers from 2013 presents the management challenge of accessing budget provisions for so many new positions and in funding the infrastructure needed to house, equip and maintain them in service. HEALTH MANAGEMENT STRUCTURE: Provincial health managers are operationally responsive to local needs, managerially responsible to provincial governments, while being concerned with adherence to central MHMS policy and to Ministry of Finance and Public Service Division regulations. The delineation of central and provincial health authorities' responsibilities requires guidelines in a changing system, where both population-based and targeted vertical programs are implemented at local levels. NUMBER AND DISTRIBUTION OF MANAGERS: Nine of the 10 positions of Provincial Health Director have experienced high turnover, which reportedly occurs without adequate handover to incoming appointees, most of whom are recent clinical graduates. Health services in the Honiara urban area are provided through the Honiara City Council. Church health services are staffed by government employees. COMPETENCE OF DISTRICT HEALTH MANAGERS: Management skills are reportedly weak at the provincial level. The Regional Assistance Mission to Solomon Islands provides governance training inputs to provincial government staff. Provincial health departments have limited financial and human resource management capacity. They also have clinical backgrounds and no training in public health planning or health services management, other than that provided by donors, the Regional Assistance Mission itself and the MHMS. MANAGEMENT WORKING ENVIRONMENT: Provincial health directors have limited control over health staff. Little supportive supervision in management is provided to new provincial health directors. No performance management systems are in place to ensure that staff are properly assessed and supported to do their best Large numbers of non-government organisations working at the provincial level in youth and women's programs require coordination by Provincial health directors to avoid duplication or implementation of programs that will require ongoing funding, but this is not done. FUNCTIONING OF MANAGEMENT SUPPORT SYSTEMS: Management support systems for budgeting and finance, management information and procurement and supply do not function adequately to support provincial health directors to manage effectively. THE SOCIO-CULTURAL CONTEXT: Socio-cultural issues such as favouritism based on kinship, discrimination against women and the big-man culture have implications for effective management and strong health leadership These cultural features create situations where a manager may be reluctant to discipline a member of their clan, or where a person with cultural influence may be able to distort systems. PMID:23240354

  13. Research workshop to research work: initial steps in establishing health research systems on Malaita, Solomon Islands

    PubMed Central

    2010-01-01

    Introduction Atoifi Adventist Hospital is a 90 bed general hospital in East Kwaio, Malaita, Solomon Islands providing services to the population of subsistence villagers of the region. Health professionals at the hospital and attached College of Nursing have considerable human capacity and willingness to undertake health research. However they are constrained by limited research experience, training opportunities, research systems, physical infrastructure and access to resources. This brief commentary describes an 'Introduction to Health Research' workshop delivered at Atoifi Adventist Hospital in September 2009 and efforts to move from 'research workshop' to 'research work'. The Approach Using a participatory-action research approach underpinned by decolonising methodologies, staff from Atoifi Adventist Hospital and James Cook University (Queensland, Australia) collaboratively designed, implemented and evaluated a health research workshop. Basic health research principles and methods were presented using active learning methodologies. Following the workshop, Atoifi Adventist Hospital and Atoifi College of Nursing staff, other professionals and community members reported an increased awareness and understanding of health research. The formation of a local Research Committee, improved ethics review procedures and the identification of local research mentors followed the week long workshop. The workshop has acted as a catalyst for research activity, increasing structural and human resource capacity for local health professionals and community leaders to engage in research. Discussion and Conclusions Participants from a variety of educational backgrounds participated in, and received benefit from, a responsive, culturally and linguistically accessible health research workshop. Improving health research systems at a remote hospital and aligning these with local and national research agendas is establishing a base to strengthen public health research and practice on Malaita, Solomon Islands. PMID:21034512

  14. Implications of urbanization for artisanal parrotfish fisheries in the Western Solomon Islands.

    PubMed

    Aswani, Shankar; Sabetian, Armagan

    2010-04-01

    Increasing migration into urbanized centers in the Solomon Islands poses a great threat to adjacent coral reef fisheries because of negative effects on the fisheries and because it further erodes customary management systems. Parrotfish fisheries are of particular importance because the feeding habits of parrotfish (scrape and excavate coral) are thought to be critical to the resilience of coral reefs and to maintaining coral reef health within marine protected areas. We investigated the ecological impact of localized subsistence and artisanal fishing pressure on parrotfish fisheries in Gizo Town, Western Solomon Islands, by analyzing the density and size distribution of parrotfish with an underwater visual census (UVC), recall diary (i.e., interviews with fishers), and creel surveys to independently assess changes in abundance and catch-per-unit-effort (CPUE) over 2 years. We then compared parrotfish data from Gizo Town with equivalent data from sites open to and closed to fishing in Kida and Nusa Hope villages, which have different customary management regimes. Results indicated a gradient of customary management effectiveness. Parrotfish abundance was greater in customary management areas closed to fishing, especially with regard to larger fish sizes, than in areas open to fishing. The decline in parrotfish abundance from 2004 to 2005 in Gizo was roughly the same magnitude as the difference in abundance decline between inside and outside customary management marine reserves. Our results highlight how weak forms of customary management can result in the rapid decline of vulnerable fisheries around urbanized regions, and we present examples in which working customary management systems (Kinda and Nusa Hope) can positively affect the conservation of parrotfish--and reef fisheries in general--in the highly biodiverse Coral Triangle region. PMID:19961509

  15. The Solomon Islands Tsunami of 6 February 2013 in the Santa Cruz Islands: Field Survey and Modeling

    NASA Astrophysics Data System (ADS)

    Fritz, Hermann M.; Papantoniou, Antonios; Biukoto, Litea; Albert, Gilly; Wei, Yong

    2014-05-01

    On February 6, 2013 at 01:12:27 UTC (local time: UTC+11), a magnitude Mw 8.0 earthquake occurred 70 km to the west of Ndendo Island (Santa Cruz Island) in the Solomon Islands. The under-thrusting earthquake near a 90° bend, where the Australian plate subducts beneath the Pacific plate generated a locally focused tsunami in the Coral Sea and the South Pacific Ocean. The tsunami claimed the lives of 10 people and injured 15, destroyed 588 houses and partially damaged 478 houses, affecting 4,509 people in 1,066 households corresponding to an estimated 37% of the population of Santa Cruz Island. A multi-disciplinary international tsunami survey team (ITST) was deployed within days of the event to document flow depths, runup heights, inundation distances, sediment and coral boulder depositions, land level changes, damage patterns at various scales, performance of the man-made infrastructure and impact on the natural environment. The 19 to 23 February 2013 ITST covered 30 locations on 4 Islands: Ndendo (Santa Cruz), Tomotu Noi (Lord Howe), Nea Tomotu (Trevanion, Malo) and Tinakula. The reconnaissance completely circling Ndendo and Tinakula logged 240 km by small boat and additionally covered 20 km of Ndendo's hard hit western coastline by vehicle. The collected survey data includes more than 80 tsunami runup and flow depth measurements. The tsunami impact peaked at Manoputi on Ndendo's densely populated west coast with maximum tsunami height exceeding 11 m and local flow depths above ground exceeding 7 m. A fast tide-like positive amplitude of 1 m was recorded at Lata wharf inside Graciosa Bay on Ndendo Island and misleadingly reported in the media as representative tsunami height. The stark contrast between the field observations on exposed coastlines and the Lata tide gauge recording highlights the importance of rapid tsunami reconnaissance surveys. Inundation distance and damage more than 500 m inland were recorded at Lata airport on Ndendo Island. Landslides were observed on volcanic Tinakula Island and on Ndendo Island. Observations from the 2013 Santa Cruz tsunami are compared against the 2007 and 2010 Solomon Islands tsunamis. The field observations in the Santa Cruz Islands present an important dataset to assess tsunami impact in the near-source region. The tsunami was also recorded at deep-ocean tsunameters and tide gauges throughout the Pacific. These observations allow us to further investigate the physics of tsunami generation caused by the seismic process (or other non-seismic mechanisms). We use numerical model MOST to analyze the large runup and complex impact distribution caused by the Santa Cruz tsunami. Source models obtained using seismic data / tsunami data are carried out to initialize the tsunami model. MOST uses two sets of numerical grids to investigate both the near- and far-field aspects of the tsunami. The basin-scale modeling results are computed using a spatial resolution of 4 arc min (approx. 7,200 m) and compared with measurements at deep-ocean tsunameters. The near-field modeling is carried out using a series of telescoped grids up to a grid resolution of tens of meters to compare with the tsunami runup and flooding extent obtained through the field survey in the Solomon Islands. The modeling results emphasize the contrast between the tsunami impact on the exposed coastline and the sheltered Lata Bay stressing the problematic interpretation of a tsunami in progress based solely on near-source tide-gauge measurements. The team also interviewed eyewitnesses and educated residents about the tsunami hazard in numerous ad hoc presentations and discussions. The combination of ancestral knowledge and recent Solomon Islands wide geohazards education programs triggered an immediate spontaneous self-evacuation containing the death toll in the small evacuation window of few minutes between the end of the ground shaking and the onslaught of the tsunami. Fortunately school children were shown a video on the 1 April 2007 Solomon Islands tsunami 3 months prior to the Santa Cruz event and the headmaster of the school at Venga evacuated the later flooded school already during a foreshock. On Tomotu Noi Island at Bamoi the residents evacuated inland towards a crocodile infested lake, which was not reached by the tsunami inundation. Community-based education and awareness programs are particularly essential to help save lives in locales at risk from near-source tsunamis.

  16. Establishing an early warning alert and response network following the Solomon Islands tsunami in 2013

    PubMed Central

    Bilve, Augustine; Nogareda, Francisco; Joshua, Cynthia; Ross, Lester; Betcha, Christopher; Durski, Kara; Fleischl, Juliet

    2014-01-01

    Abstract Problem On 6 February 2013, an 8.0 magnitude earthquake generated a tsunami that struck the Santa Cruz Islands, Solomon Islands, killing 10 people and displacing over 4700. Approach A post-disaster assessment of the risk of epidemic disease transmission recommended the implementation of an early warning alert and response network (EWARN) to rapidly detect, assess and respond to potential outbreaks in the aftermath of the tsunami. Local setting Almost 40% of the Santa Cruz Islands population were displaced by the disaster, and living in cramped temporary camps with poor or absent sanitation facilities and insufficient access to clean water. There was no early warning disease surveillance system. Relevant changes By 25 February, an EWARN was operational in five health facilities that served 90% of the displaced population. Eight priority diseases or syndromes were reported weekly; unexpected health events were reported immediately. Between 25 February and 19 May, 1177 target diseases or syndrome cases were reported. Seven alerts were investigated. No sustained transmission or epidemics were identified. Reporting compliance was 85%. The EWARN was then transitioned to the routine four-syndrome early warning disease surveillance system. Lesson learnt It was necessary to conduct a detailed assessment to evaluate the risk and potential impact of serious infectious disease outbreaks, to assess whether and how enhanced early warning disease surveillance should be implemented. Local capacities and available resources should be considered in planning EWARN implementation. An EWARN can be an opportunity to establish or strengthen early warning disease surveillance capabilities. PMID:25378746

  17. Hospital Visits Due to Domestic Violence from 1994 to 2011 in the Solomon Islands: A Descriptive Case Series

    PubMed Central

    Negin, Joel; Houasia, Patrick; Munamua, Alex B; Leon, David P; Rimon, Mia; Martiniuk, Alexandra LC

    2014-01-01

    The Solomon Islands has one of the highest rates of domestic violence in the world. This paper is a descriptive case series of all cases of domestic violence presenting to the Solomon Islands National Referral Hospital (NRH) over 18 years. Data were routinely collected from a database of all patients who were treated by NRH general surgery and orthopedic clinicians between 1994 and 2011, inclusive. The total number of cases in the injury database as a result of domestic violence was 387. The average number of cases in the database per year from 1994 to 2011 was 20. There were 6% more female patients (205 of 387; 53%) than male (182 of 387; 47%). Of the cases in which the perpetrator of the violence against a female patient was specified (111 of 205 female cases), 74% (82 of 111) were the patient's husband. Only 5% (5 of 111) of cases in females were inflicted by another female. This analysis provides the best available information on domestic violence cases requiring a visit to a tertiary hospital in a Pacific Island in the specified time period and is undoubtedly an under-estimate of the total cases of domestic violence. Preventing and treating domestic violence in the Solomon Islands and in the Pacific is an important challenge and there is a significant role for secondary and tertiary health services in screening for and preventing domestic violence. PMID:25285254

  18. Resumption of traditional drive hunting of dolphins in the Solomon Islands in 2013.

    PubMed

    Oremus, Marc; Leqata, John; Baker, C Scott

    2015-05-01

    The 'drive hunting' of dolphins has a long history in the Solomon Islands, specifically at the island of Malaita. In 2010, the most active village, Fanalei, suspended hunting in exchange for financial compensation from an international non-governmental organization but resumed hunting again in early 2013. Here, we report on a visit to Fanalei in March 2013 to document the species and number of dolphins killed in the renewed hunting. Detailed records for the 2013 hunting, up to the time of our visit, included at least 1500 pantropical spotted dolphins (Stenella attenuata), 159 spinner dolphins (Stenella longirostris) and 15 'bottlenose' dolphins, probably Tursiops truncatus. Molecular identification confirmed two of the species, pantropical spotted and spinner dolphins. A summary of all available records from 1976 to 2013 documented a minimum total of 15?454 dolphins killed by the Fanalei villagers alone. We also found the local price of a dolphin tooth had increased from about US$0.14 (SBD$1) in 2004 to about US$0.70 (SBD$5) in 2013. The large number of dolphins killed and the apparent incentive for future hunting offered by the increasing commercial value of teeth, highlight an urgent need to monitor hunts and assess the abundance and trends in local populations. PMID:26064656

  19. The energetic 2010 MW 7.1 Solomon Islands tsunami earthquake

    NASA Astrophysics Data System (ADS)

    Newman, Andrew V.; Feng, Lujia; Fritz, Hermann M.; Lifton, Zachery M.; Kalligeris, Nikos; Wei, Yong

    2011-08-01

    On 2010 January 3 a moment magnitude MW 7.1 earthquake struck the Solomon Islands very near the San Cristobal trench, causing extensive landslides and surprisingly large tsunami waves. Because of the unique proximity of islands to the trench (<20 km) and earthquake, a post-seismic survey successfully identified unexpected widespread coseismic subsidence towards the trench (up to 80 cm), with no discernable post-seismic deformation. Approximately 1000 km from the earthquake ocean-bottom pressure sensors measured 1-2 cm open-ocean tsunami waves. Though spatially limited, the local tsunami wave heights up to 7 m were comparable to the much larger adjacent 2007 MW 8.1 earthquake. The seismically determined focal mechanism, broad-scale subsidence, tsunami amplitude and open ocean wave heights are all explained by an extremely shallow low-angle thrust adjacent to the impinging subduction of the two seamounts near the trench. This event belongs to a potentially new class of shallow 'tsunami earthquakes' that is not identified as deficient in radiated seismic energy.

  20. Keeping Food on the Table: Human Responses and Changing Coastal Fisheries in Solomon Islands

    PubMed Central

    2015-01-01

    Globally the majority of commercial fisheries have experienced dramatic declines in stock and catch. Likewise, projections for many subsistence fisheries in the tropics indicate a dramatic decline is looming in the coming decades. In the Pacific Islands coastal fisheries provide basic subsistence needs for millions of people. A decline in fish catch would therefore have profound impacts on the health and livelihoods of these coastal communities. Given the decrease in local catch rates reported for many coastal communities in the Pacific, it is important to understand if fishers have responded to ecological change (either by expanding their fishing range and/or increasing their fishing effort), and if so, to evaluate the costs or benefits of these responses. We compare data from fish catches in 1995 and 2011 from a rural coastal community in Solomon Islands to examine the potentially changing coastal reef fishery at these time points. In particular we found changes in preferred fishing locations, fishing methodology and catch composition between these data sets. The results indicate that despite changes in catch rates (catch per unit effort) between data collected in 2011 and 16 years previously, the study community was able to increase gross catches through visiting fishing sites further away, diversifying fishing methods and targeting pelagic species through trolling. Such insight into local-scale responses to changing resources and/or fisheries development will help scientists and policy makers throughout the Pacific region in managing the region’s fisheries in the future. PMID:26158694

  1. Resumption of traditional drive hunting of dolphins in the Solomon Islands in 2013

    PubMed Central

    Oremus, Marc; Leqata, John; Baker, C. Scott

    2015-01-01

    The ‘drive hunting’ of dolphins has a long history in the Solomon Islands, specifically at the island of Malaita. In 2010, the most active village, Fanalei, suspended hunting in exchange for financial compensation from an international non-governmental organization but resumed hunting again in early 2013. Here, we report on a visit to Fanalei in March 2013 to document the species and number of dolphins killed in the renewed hunting. Detailed records for the 2013 hunting, up to the time of our visit, included at least 1500 pantropical spotted dolphins (Stenella attenuata), 159 spinner dolphins (Stenella longirostris) and 15 ‘bottlenose’ dolphins, probably Tursiops truncatus. Molecular identification confirmed two of the species, pantropical spotted and spinner dolphins. A summary of all available records from 1976 to 2013 documented a minimum total of 15 454 dolphins killed by the Fanalei villagers alone. We also found the local price of a dolphin tooth had increased from about US$0.14 (SBD$1) in 2004 to about US$0.70 (SBD$5) in 2013. The large number of dolphins killed and the apparent incentive for future hunting offered by the increasing commercial value of teeth, highlight an urgent need to monitor hunts and assess the abundance and trends in local populations. PMID:26064656

  2. Education and Libraries in the Solomon Islands: A Bibliography of English-Language Books, Documents, Papers, Theses and Dissertations and Journal Articles.

    ERIC Educational Resources Information Center

    Sperry, Robert

    The Solomon Islands are a scattered Melanesian archipelago in the southwestern Pacific Ocean. There are 21 large islands and numerous smaller ones with a total population of 285,766 in 1986. About two-thirds of school-age children attend organized schools. The literacy rate of the islands was reported at 17 percent in 1980. Approximately 30

  3. Solomon Islands largest hawksbill turtle rookery shows signs of recovery after 150 years of excessive exploitation.

    PubMed

    Hamilton, Richard J; Bird, Tomas; Gereniu, Collin; Pita, John; Ramohia, Peter C; Walter, Richard; Goerlich, Clara; Limpus, Colin

    2015-01-01

    The largest rookery for hawksbill turtles in the oceanic South Pacific is the Arnavon Islands, which are located in the Manning Strait between Isabel and Choiseul Province, Solomon Islands. The history of this rookery is one of overexploitation, conflict and violence. Throughout the 1800s Roviana headhunters from New Georgia repeatedly raided the Manning Strait to collect hawksbill shell which they traded with European whalers. By the 1970s the Arnavons hawksbill population was in severe decline and the national government intervened, declaring the Arnavons a sanctuary in 1976. But this government led initiative was short lived, with traditional owners burning down the government infrastructure and resuming intensive harvesting in 1982. In 1991 routine beach monitoring and turtle tagging commenced at the Arnavons along with extensive community consultations regarding the islands' future, and in 1995 the Arnavon Community Marine Conservation Area (ACMCA) was established. Around the same time national legislation banning the sale of all turtle products was passed. This paper represents the first analysis of data from 4536 beach surveys and 845 individual turtle tagging histories obtained from the Arnavons between 1991-2012. Our results and the results of others, reveal that many of the hawksbill turtles that nest at the ACMCA forage in distant Australian waters, and that nesting on the Arnavons occurs throughout the year with peak nesting activity coinciding with the austral winter. Our results also provide the first known evidence of recovery for a western pacific hawksbill rookery, with the number of nests laid at the ACMCA and the remigration rates of turtles doubling since the establishment of the ACMCA in 1995. The Arnavons case study provides an example of how changes in policy, inclusive community-based management and long term commitment can turn the tide for one of the most charismatic and endangered species on our planet. PMID:25853880

  4. The contribution of nearshore fish aggregating devices (FADs) to food security and livelihoods in Solomon Islands.

    PubMed

    Albert, Joelle A; Beare, Doug; Schwarz, Anne-Maree; Albert, Simon; Warren, Regon; Teri, James; Siota, Faye; Andrew, Neil L

    2014-01-01

    Fish aggregating devices, or FADs, are used widely in developing countries to concentrate pelagic fish, making them easier to catch. Nearshore FADs anchored close to the coast allow access for rural communities, but despite their popularity among policy makers, there is a dearth of empirical analysis of their contributions to the supply of fish and to fisheries management. In this paper we demonstrate that nearshore FADs increased the supply of fish to four communities in Solomon Islands. Estimated total annual fish catch ranged from 4300 to 12,000 kg across the study villages, with nearshore FADs contributing up to 45% of the catch. While it is clear that FADs increased the supply of fish, FAD catch rates were not consistently higher than other fishing grounds. Villages with limited access to diverse or productive fishing grounds seemingly utilized FADs to better effect. Villagers believed FADs increased household income and nutrition, as well as providing a source of fish for community events. FADs were also perceived to increase intra-household conflict and reduce fishers' participation in community activities. FADs need to be placed within a broader rural development context and treated as another component in the diversified livelihoods of rural people; as with other livelihood options they bring trade-offs and risks. PMID:25513808

  5. The Contribution of Nearshore Fish Aggregating Devices (FADs) to Food Security and Livelihoods in Solomon Islands

    PubMed Central

    Albert, Joelle A.; Beare, Doug; Schwarz, Anne-Maree; Albert, Simon; Warren, Regon; Teri, James; Siota, Faye; Andrew, Neil L.

    2014-01-01

    Fish aggregating devices, or FADs, are used widely in developing countries to concentrate pelagic fish, making them easier to catch. Nearshore FADs anchored close to the coast allow access for rural communities, but despite their popularity among policy makers, there is a dearth of empirical analysis of their contributions to the supply of fish and to fisheries management. In this paper we demonstrate that nearshore FADs increased the supply of fish to four communities in Solomon Islands. Estimated total annual fish catch ranged from 4300 to 12 000 kg across the study villages, with nearshore FADs contributing up to 45% of the catch. While it is clear that FADs increased the supply of fish, FAD catch rates were not consistently higher than other fishing grounds. Villages with limited access to diverse or productive fishing grounds seemingly utilized FADs to better effect. Villagers believed FADs increased household income and nutrition, as well as providing a source of fish for community events. FADs were also perceived to increase intra-household conflict and reduce fishers' participation in community activities. FADs need to be placed within a broader rural development context and treated as another component in the diversified livelihoods of rural people; as with other livelihood options they bring trade-offs and risks. PMID:25513808

  6. Solomon Islands Largest Hawksbill Turtle Rookery Shows Signs of Recovery after 150 Years of Excessive Exploitation

    PubMed Central

    Hamilton, Richard J.; Bird, Tomas; Gereniu, Collin; Pita, John; Ramohia, Peter C.; Walter, Richard; Goerlich, Clara; Limpus, Colin

    2015-01-01

    The largest rookery for hawksbill turtles in the oceanic South Pacific is the Arnavon Islands, which are located in the Manning Strait between Isabel and Choiseul Province, Solomon Islands. The history of this rookery is one of overexploitation, conflict and violence. Throughout the 1800s Roviana headhunters from New Georgia repeatedly raided the Manning Strait to collect hawksbill shell which they traded with European whalers. By the 1970s the Arnavons hawksbill population was in severe decline and the national government intervened, declaring the Arnavons a sanctuary in 1976. But this government led initiative was short lived, with traditional owners burning down the government infrastructure and resuming intensive harvesting in 1982. In 1991 routine beach monitoring and turtle tagging commenced at the Arnavons along with extensive community consultations regarding the islands’ future, and in 1995 the Arnavon Community Marine Conservation Area (ACMCA) was established. Around the same time national legislation banning the sale of all turtle products was passed. This paper represents the first analysis of data from 4536 beach surveys and 845 individual turtle tagging histories obtained from the Arnavons between 1991-2012. Our results and the results of others, reveal that many of the hawksbill turtles that nest at the ACMCA forage in distant Australian waters, and that nesting on the Arnavons occurs throughout the year with peak nesting activity coinciding with the austral winter. Our results also provide the first known evidence of recovery for a western pacific hawksbill rookery, with the number of nests laid at the ACMCA and the remigration rates of turtles doubling since the establishment of the ACMCA in 1995. The Arnavons case study provides an example of how changes in policy, inclusive community-based management and long term commitment can turn the tide for one of the most charismatic and endangered species on our planet. PMID:25853880

  7. Population genetics of Plasmodium falciparum and Plasmodium vivax and asymptomatic malaria in Temotu Province, Solomon Islands

    PubMed Central

    2013-01-01

    Background Temotu Province, Solomon Islands is progressing toward malaria elimination. A baseline survey conducted in 2008 showed that most Plasmodium infections in the province were of low parasite density and asymptomatic infections. To better understand mechanisms underlying these malaria transmission characteristics genetic diversity and relationships among Plasmodium falciparum and Plasmodium vivax populations in the province were examined. Methods Forty-five P. falciparum and 67 P. vivax samples collected in the 2008 baseline survey were successfully genotyped using eight P. falciparum and seven P. vivax microsatellite markers. Genetic diversity, relationships and distribution of both P. falciparum and P. vivax populations were analysed. Results Plasmodium falciparum population exhibited low diversity with 19 haplotypes identified and had closely related clusters indicating clonal expansion. Interestingly, a dominant haplotype was significantly associated with fever and high parasite density. In contrast, the P. vivax population was highly diverse with 58 haplotypes identified that were not closely related. Parasite populations between different islands in the province showed low genetic differentiation. Conclusion The low diversity and clonal population of P. falciparum population may partially account for clinical immunity developed against illness. However, it is possible that importation of a new P. falciparum strain was the major cause of illness. High diversity in P. vivax population and low relatedness between strains suggested clinical immunity to P. vivax may be maintained by different mechanisms. The genetic diversity, population structure and distribution of strains indicate that transmission of P. falciparum was low, but that of P. vivax was still high in 2008. These data will be useful for assessing changes in malaria transmission resulting from interventions. PMID:24261646

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

    USGS Publications Warehouse

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

    1998-01-01

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

  9. American Dissertations on Foreign Education: A Bibliography with Abstracts. Volume XVII. Pacific: American Samoa, Fiji, Guam, Papua New Guinea, Ryukyu Islands, Solomon Islands, Tonga, Trust Territory of the Pacific Islands (Micronesia), Tubuai (French Polynesia), Western Samoa.

    ERIC Educational Resources Information Center

    Parker, Franklin, Ed.; Parker, Betty June, Ed.

    The editors attempt to examine and abstract all locatable doctoral dissertations completed in the United States, Canada, and some European countries that pertain to the Pacific area. Specifically, these dissertations deal with American Samoa, Fiji, Guam, Papua New Guinea, Ryukyu Islands, Solomon Islands, Tonga, Trust Territory of the Pacific

  10. Strengthening capacity for local evidence to inform local responses to HIV in a remote Solomon Islands health service

    PubMed Central

    Redman-MacLaren, Michelle; Timothy-Harrington, Relmah; Asugeni, Rowena; Muse, Elmah; Jimuru, Emmy; Moutoa, Kenny; Speare, Rick

    2015-01-01

    Background Documenting specific knowledge and attitudes about HIV in the culturally diverse nation of Solomon Islands is essential to inform locally targeted public health responses. As part of a large capacity-strengthening project at Atoifi Adventist Hospital in East Kwaio, Solomon Islands, researchers, using a learn-by-doing process, worked with participants in public health research methods. Methods Overall, 43 people attended research capacity building workshops in 2011; eight joined the HIV study group. A cross-sectional survey including semi-structured interviews on HIV was conducted by the group. In February 2014, a hospital administrator was interviewed about how the 2011 study informed local HIV responses. Results Of the 53 survey participants, 64% self-assessed as having little or no HIV knowledge, but 90% knew HIV could be transmitted between men and women during sex. Less than 50% knew HIV could be transmitted between two men having sex, 45% thought HIV could be transmitted by mosquitoes and 55% agreed condoms help protect from HIV. Most participants reported negative attitudes towards people with HIV. Three years later the health administrator reported ad hoc responses to HIV because of low HIV prevalence, increasing noncommunicable diseases, staff turnover and resource shortages. Discussion This HIV study was used to strengthen research skills in local health professionals and community members in Solomon Islands. It showed that community members require accurate information about HIV transmission and that entrenched stigma is an issue. Although results provided local evidence for local response, ongoing health system challenges and little local HIV transmission meant HIV services remain rudimentary. PMID:26306218

  11. Replicated Stalagmite Records of Rainfall Variability in the Solomon Islands since the Little Ice Age

    NASA Astrophysics Data System (ADS)

    Maupin, C. R.; Partin, J. W.; Quinn, T. M.; Shen, C.; Banner, J. L.; lin, K.; Taylor, F. W.; Sinclair, D.

    2011-12-01

    The tropical west Pacific warm pool (WPWP) and south Pacific convergence zone (SPCZ) play integral roles in global climate variability. Convection over the WPWP is a source of latent heat and moisture to extratropical latitudes and, in the region of the SPCZ, forms a center of action for the rising component of the zonal Pacific Walker circulation. The nature of pre-instrumental, and therefore pre-industrial, variability of convection associated with the WPWP since the Little Ice Age (LIA) is known only from sparse and spatially disparate records. As a result, it is difficult to form a robust framework on which to base estimates of future variability of zonal atmospheric circulation within the region, an important prospect given predicted weakening in the Pacific Walker circulation under global warming conditions. Here we present absolutely dated, subannually resolved, partially replicated oxygen isotope records, spanning 1420-2010 CE, from two fast growing (~2 mm yr-1) calcite speleothems from a cave in northern Guadalcanal, Solomon Islands (9.5 S, 160 E). Guadalcanal is located both within the WPWP and under the zonally oriented portion of the SPCZ. A strong degree of reproducibility between the two stalagmite ?18O time series, within dating uncertainties, favors the interpretation that the stalagmite ?18O variability is a reflection of climatic conditions over the cave, however we continue to assess the possibility of influence by any potential non-climatic processes. We assert that speleothem ?18O variability reflects changes in rainfall based on the isotope "amount effect" observed in the tropics. We find rainfall here has varied considerably on decadal to multidecadal timescales since the LIA and hypothesize a relationship between this variability and variability in the strength of shallow Pacific meridional overturning circulation (PMOC). Changes in the PMOC are thought to be responsible for decadal variability in central and eastern equatorial Pacific SST anomalies as well as anomalies in Pacific tradewind strength. Such variability could affect convergence and vertical motion in the zonally oriented portion of the SPCZ. We find no clear long-term trend associated with changes in total solar irradiance since the LIA, in contrast to equatorial and northern hemisphere proxy records of tropical Pacific ocean-atmosphere variability.

  12. 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.

  13. Preliminary Volcano-Hazard Assessment for Gareloi Volcano, Gareloi Island, Alaska

    USGS Publications Warehouse

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

    2008-01-01

    Gareloi Volcano (178.794 degrees W and 51.790 degrees N) is located on Gareloi Island in the Delarof Islands group of the Aleutian Islands, about 2,000 kilometers west-southwest of Anchorage and about 150 kilometers west of Adak, the westernmost community in Alaska. This small (about 8x10 kilometer) volcano has been one of the most active in the Aleutians since its discovery by the Bering expedition in the 1740s, though because of its remote location, observations have been scant and many smaller eruptions may have gone unrecorded. Eruptions of Gareloi commonly produce ash clouds and lava flows. Scars on the flanks of the volcano and debris-avalanche deposits on the adjacent seafloor indicate that the volcano has produced large landslides in the past, possibly causing tsunamis. Such events are infrequent, occurring at most every few thousand years. The primary hazard from Gareloi is airborne clouds of ash that could affect aircraft. In this report, we summarize and describe the major volcanic hazards associated with Gareloi.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  15. Agroforestry In-Service Training. A Training Aid for Asia & the Pacific Islands (Honiara, Solomon Islands, South Pacific, October 23-29, 1983). Training for Development. Peace Corps Information Collection & Exchange Training Manual No. T-16.

    ERIC Educational Resources Information Center

    Fillion, Jacob; Weeks, Julius

    The Forestry/Natural Resources Sector in the Office of Training and Program Support of the Peace Corps conducted an agroforestry inservice training workshop in Honiara, Solomon Islands, in 1983. Participants included Peace Corps volunteers and their host country national counterparts from six countries of the Pacific Islands and Asia (Western

  16. Control of scabies, skin sores and haematuria in children in the Solomon Islands: another role for ivermectin.

    PubMed Central

    Lawrence, Gregor; Leafasia, Judson; Sheridan, John; Hills, Susan; Wate, Janet; Wate, Christine; Montgomery, Janet; Pandeya, Nirmala; Purdie, David

    2005-01-01

    OBJECTIVE: To assess the effects of a 3-year programme aimed at controlling scabies on five small lagoon islands in the Solomon Islands by monitoring scabies, skin sores, streptococcal skin contamination, serology and haematuria in the island children. METHODS: Control was achieved by treating almost all residents of each island once or twice within 2 weeks with ivermectin (160-250 microg/kg), except for children who weighed less than 15 kg and pregnant women, for whom 5% permethrin cream was used. Reintroduction of scabies was controlled by treating returning residents and visitors, whether or not they had evident scabies. FINDINGS: Prevalence of scabies dropped from 25% to less than 1% (P < 0.001); prevalence of sores from 40% to 21% (P < 0.001); streptococcal contamination of the fingers in those with and without sores decreased significantly (P = 0.02 and 0.047, respectively) and anti-DNase B levels decreased (P = 0.002). Both the proportion of children with haematuria and its mean level fell (P = 0.002 and P < 0.001, respectively). No adverse effects of the treatments were seen. CONCLUSION: The results show that ivermectin is an effective and practical agent in the control of scabies and that control reduces the occurrence of streptococcal skin disease and possible signs of renal damage in children. Integrating community-based control of scabies and streptococcal skin disease with planned programmes for controlling filariasis and intestinal nematodes could be both practical and produce great health benefits. PMID:15682247

  17. Assessing the effects of changing demographic and consumption patterns on sea tenure regimes in the Roviana Lagoon, Solomon Islands.

    PubMed

    Aswani, Shankar

    2002-06-01

    This paper investigates how sea tenure institutions in the Roviana Lagoon, Solomon Islands, mediate among population, consumption, and the environment. The focus is on explaining how growth in population and consumption alter sea tenure regimes, and the factors that shape either their institutional robustness or vulnerability. The paper also addresses the regional differences among sea tenure institutional arrangements, the processes that are producing them, and the social and environmental outcomes of these institutions as they engage external forces and internal changes. A major question is how existing forms of sea tenure respond comparatively when faced with parallel demographic and economic transformations? Two villages representing different sea tenure arrangements within the Roviana Lagoon are compared. Results show that inhabitants in these villages perceive their systems of sea tenure governance similarly; yet their managerial responses to changes brought about by growth in population and consumption differ, and the responses produce contrasting environmental effects. PMID:12174597

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

    NASA Astrophysics Data System (ADS)

    Carmona, E.; Almendros, J.; Martn, R.; Corts, G.; Alguacil, G.; Moreno, J.; Martn, B.; Martos, A.; Serrano, I.; Stich, D.; Ibez, 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 Geofsica 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.

  19. 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.

  20. Formation and Evolution of the San Cristobal Trough Transform Fault Linking the Southern Solomon Islands and Northern New Hebrides Trenches

    NASA Astrophysics Data System (ADS)

    Furlong, K. P.; Hayes, G. P.; Herman, M. W.; Benz, H.

    2014-12-01

    The San Cristobal Trough, which occupies the southern segment of the South Solomon Trench, hosts a dominantly left-lateral transform plate boundary (SCTF) linking the southern end of the Solomon Islands subduction zone (SISZ) to the northern end of the New Hebrides (Vanuatu) subduction zone (NHSZ). At its western end (SISZ), the Australia plate is torn as a result of the transition from subduction to transform motion. The southern side of the tear translates approximately 375 km along the SCTF before subducting beneath the Santa Cruz Islands at the NHSZ. Earthquakes occurring along this transform reflect the processes of plate tearing, fault zone evolution, and subsequent underthrusting and subduction of the Australia-plate-side of the transform. A knot of earthquake activity at the western end of the SCTF juxtaposes high-angle thrust faulting events with left-lateral strike slip events. These record the tearing of Australian lithosphere, as shown by a recent pair of large earthquakes in that region - a Mw 7.6 strike-slip event (12 April 2014) followed 22 hours later by a Mw 7.4 high-angle reverse faulting event (13 April 2014). Associated displacements reflect oblique tearing (northern-side down and west), allowing the Australia Plate to follow two disparate paths - subduction at the SISZ to the north and translation along the SCTF to the south. Moving eastward along the transform, the plate boundary shows three styles of earthquake activity. The main transform is dominated by shallow, E-W striking, left-lateral faulting and E-W striking thrust faults (with a north-dipping shallow fault plane) - these reflect partitioning of oblique motion along the transform between the Australia and Pacific plates. Outboard (+/- 100 km) of the plate boundary, a group of E-W striking shallow normal faulting events reflect upward bending driven by the convergent component of plate motions. Approaching the NHSZ, normal faulting earthquakes in the Australia Plate rotate clockwise, consistent with outer-rise normal faulting of the NHSZ.

  1. Malaria elimination in Isabel Province, Solomon Islands: establishing a surveillance-response system to prevent introduction and reintroduction of malaria

    PubMed Central

    2011-01-01

    Background The Solomon Islands National Malaria Programme is currently focused on intensified control and progressive elimination. Recent control efforts in Isabel Province have reduced their malaria incidence to 2.6/1,000 population in 2009 [1] whereas most neighbouring provinces have much higher incidences. A malaria surveillance-response system that involves testing all travellers entering Isabel Province using rapid diagnostic tests (RDT) to prevent cases being imported had been proposed by local health authorities. This study provides information on the feasibility and acceptability of implementing a new approach of surveillance and response in the context of low levels of indigenous malaria transmission in Isabel Province. Methods A total of 13 focus group discussions (FGD) and 22 key informant interviews (KII) were conducted in Isabel Province, Solomon Islands. Key topics included: the travel patterns of people to, from and within Isabel Province; the acceptability, community perceptions, attitudes and suggestions towards the proposed surveillance programme; and management of suspected malaria cases. This information was triangulated with data obtained from port authorities, airlines and passenger ships travelling to and from Isabel Province in the preceding two years. Results Travel within Isabel Province and to and from other provinces is common with marked seasonality. The majority of inter-provincial travel is done on scheduled public transport; namely passenger ships and aircrafts. In Isabel Province there is a healthy community spirit as well as high concern regarding malaria and its importation and there is currently effective malaria passive case detection and management. Conducting malaria screening at ports and airports would be acceptable to the community. Conclusion A robust surveillance-response system is essential when moving towards malaria elimination. Many factors contribute positively towards the feasibility of an RDT based malaria surveillance system in Isabel Province. Due to financial and logistical restraints local health authorities have concluded that a system of community-based vigilance to identify new arrivals in villages and direct them to have malaria testing is more feasible than formal screening at ports and airports. A surveillance response system to prevent introduction of malaria into Isabel Province can be integrated into the National Malaria Control Programme provided the operational steps are carefully planned with regards to human and financial resources. PMID:21834995

  2. 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 m/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.

  3. 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.

  4. Supporting Pacific Island Countries to Strengthen Their Resistance to Tobacco Industry Interference in Tobacco Control: A Case Study of Papua New Guinea and Solomon Islands

    PubMed Central

    McCool, Judith; McKenzie, Jeanie; Lyman, Annabel; Allen, Matthew

    2013-01-01

    Tobacco use is the biggest single preventable cause of non-communicable diseases (NCDs) in the Western Pacific region. Currently, 14 Pacific Island countries have ratified the WHO Framework Convention on Tobacco Control (FCTC) and, in having done so, are committed to implementing tobacco control measures aligned with the FCTC. Progressing strong and effective tobacco control legislation is essential to achieving long term gains in public health in small island countries. However, survey evidence suggests that pervasive tobacco industry interference serves to undermine tobacco control and public policy in several Pacific countries. An initiative was developed to provide dedicated, in-country technical support for developing legislation and policy to support implementation of Article 5.3 of the FCTC in the Solomon Islands and Papua New Guinea. This paper examines the factors that have assisted the two Pacific countries to make progress in implementing Article 5.3 and what this might mean for supporting progress in other Pacific settings. A document analysis was undertaken to identify the process and outcome of the intervention. Two significant outputs from the project including having identified and documented specific examples of TII and the development of draft legislation for Article 5.3 and other key resources for public servants both within and outside the health sector. Key determinants of progress included a motivated and engaged Ministry of Health, active civil society group or champion and access to media to prepare tobacco industry related material to stimulate public and policy sector debate. PMID:23924884

  5. From 'what' to 'how' -- capacity building in health promotion for HIV/AIDS prevention in the Solomon Islands.

    PubMed

    McPhail-Bell, Karen; MacLaren, David; Isihanua, Angela; MacLaren, Michelle

    2007-09-01

    This paper describes a capacity building process undertaken within the HIV/AIDS prevention project of the Adventist Development and Relief Agency (ADRA) in the Solomon Islands. ADRA HIV/AIDS has recently reoriented its project structure, moving beyond its awareness raising approach to incorporate health promotion frameworks, theories, strategies and assumptions. These have been used to inform project practice in project planning, delivery and evaluation. This paper shares what has worked and not worked in the capacity building process, including a project evaluation of the initial HIV/AIDS awareness raising project and the application of a number of capacity building strategies, including utilising a volunteer Australian Youth Ambassador for Development (AYAD) funded by the Australian Agency for International Development (AusAID). Existing and new projects are outlined. The underlying theme is that any capacity building exercise must include structural support (e.g. management, national frameworks) to ensure the incorporation of new initiatives and approaches. With time this enables ownership by counterparts and external partnerships to develop. The presence of an AYAD volunteer has been an effective strategy to achieve this. Reflections from the evaluators, the AYAD volunteer and the HIV/AIDS team are included. PMID:19588619

  6. Preparedness of Pre-Service Teachers for Inclusive Education in the Solomon Islands

    ERIC Educational Resources Information Center

    Sharma, Umesh; Simi, Janine; Forlin, Chris

    2015-01-01

    Recent policy changes in the Pacific Islands have seen a strong emphasis on implementing inclusive education. Preparing teachers for this change in education will be essential if they are to have the knowledge, skills and understandings so that they can become inclusive practitioners. Pre-service teacher education will play a critical role in

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

    SciTech Connect

    Bhattacharya, A.; Reddy, C.S.S.; Srivastav, S.K. )

    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.

  8. Diet and social status on Taumako, a Polynesian outlier in the Southeastern Solomon Islands.

    PubMed

    Kinaston, Rebecca L; Buckley, Hallie R; Gray, Andrew

    2013-08-01

    Stable isotopes (δ(13)C, δ(15)N, and δ(34)S) are used to characterize the diet of the adult individuals (n = 99) interred in the Namu burial ground located on the Polynesian outlier of Taumako (∼300-750 BP). Polynesian outliers are islands on the fringe of Remote Oceania that were inhabited by a back migration of populations from Polynesia during prehistory. As a result of admixture with nearby island communities, little is known about the social structure and social diversity of the prehistoric inhabitants of Taumako. The distribution of prestige grave goods within the Namu cemetery has been used as evidence to support the premise that Taumakoan social structure was stratified like Polynesian societies. Here we test the hypothesis that "wealthy" individuals and males will display isotopic ratios indicative of the consumption of "high status" foods in the Pacific islands such as pork, chicken, sea turtle, and pelagic fish. The isotope results suggest the δ(34) S values were diagenetically altered, possibly an effect of volcanism. The carbon and nitrogen stable isotope ratios indicate that the diet of all the individuals included a mixture of C3 terrestrial plant foods (likely starchy staples such as yam, taro, and breadfruit, in addition to nuts) and a variety of marine resources, including reef and pelagic fish. The stable isotope results indicate that wealthy individuals and males were eating more foods from higher trophic levels, interpreted as being high status animal foods. The socially differentiated food consumption patterns are discussed within a Pacific island context. PMID:23868172

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    On April 23, 2014, Ahyi Volcano, a submarine cone in the Northern Mariana Islands (NMI), ended a 13-year-long period of repose with an explosive eruption lasting over 2 weeks. The remoteness of the volcano and the presence of several seamounts in the immediate area posed a challenge for constraining the source location of the eruption. Critical to honing in on the Ahyi area quickly were quantitative error estimates provided by the CTBTO on the backazimuth of hydroacoustic arrivals observed at Wake Island (IMS station H11). T-phases registered across the NMI seismic network at the rate of approximately 10 per hour until May 8 and were observed in hindsight at seismic stations on Guam and Chichijima. After May 8, sporadic T-phases were observed until May 17. Within days of the eruption onset, reports were received from NOAA research divers of hearing explosions underwater and through the hull on the ship while working on the SE coastline of Farallon de Pajaros (Uracas), a distance of 20 km NW of Ahyi. In the same area, the NOAA crew reported sighting mats of orange-yellow bubbles on the water surface and extending up to 1 km from the shoreline. Despite these observations, satellite images showed nothing unusual throughout the eruption. During mid-May, a later cruise leg on the NOAA ship Hi'ialakai that was previously scheduled in the Ahyi area was able to collect some additional data in response to the eruption. Preliminary multibeam sonar bathymetry and water-column CTD casts were obtained at Ahyi. Comparison between 2003 and 2014 bathymetry revealed that the minimum depth had changed from 60 m in 2003 to 75 m in 2014, and a new crater ~95 m deep had formed at the summit. Extending SSE from the crater was a new scoured-out landslide chute extending downslope to a depth of at least 2300 m. Up to 125 m of material had been removed from the head of the landslide chute and downslope deposits were up to 40 m thick. Significant particle plumes were detected at all three CTD casts of Ahyi volcano. Plumes with optical anomalies up to 0.4 NTU were found south and west of Ahyi at 100-175 m water depth, corresponding to the depth of the new summit crater. We plan to combine the extensive T-phase, hydroacoustic, CTD, and bathymetry data from Ahyi to characterize submarine volcanic processes and quantify the size and total radiated energy of the eruption.

  10. A marked decline in the incidence of malaria in a remote region of Malaita, Solomon Islands, 2008 to 2013

    PubMed Central

    Oloifana-Polosovai, Hellen; Gwala, John; Harrington, Humpress; Massey, Peter D; Ribeyro, Elmer; Flores, Angelica; Speare, Christopher; McBride, Edwin; MacLaren, David

    2014-01-01

    Setting Atoifi Adventist Hospital (AAH), Solomon Islands, the only hospital in the East Kwaio region. Objective To use routine surveillance data to assess the trends in malaria from 2008 to 2013. Design Descriptive study of records from (1) AAH laboratory malaria records; (2) admissions to AAH for malaria; and (3) malaria treatments from outpatient records. Results AAH examined 35 608 blood films and diagnosed malaria in 4443 samples comprised of 2667 Plasmodium falciparum (Pf) and 1776 Plasmodium vivax (Pv). Between 2008 and 2013 the total number of malaria cases detected annually decreased by 86.5%, Pf by 96.7% and Pv by 65.3%. The ratio of Pf to Pv reversed in 2010 from 2.06 in 2008 to 0.19 in 2013. For 2013, Pf showed a seasonal pattern with no cases diagnosed in four months. From 2008 to 2013 admissions in AAH for malaria declined by 90.8%, and malaria mortality fell from 54 per 100 000 to zero. The annual parasite index (API) for 2008 and 2013 was 195 and 24, respectively. Village API has identified a group of villages with higher malaria incidence rates. Conclusion The decline in malaria cases in the AAH catchment area has been spectacular, particularly for Pf. This was supported by three sources of hospital surveillance data (laboratory, admissions and treatment records). The decline was associated with the use of artemisinin-based combined therapy and improved vertical social capital between the AAH and the local communities. Calculating village-specific API has highlighted which villages need to be targeted by the AAH malaria control team. PMID:25320674

  11. Origin of the oceanic basalt basement of the Solomon Islands arc and its relationship to the Ontong Java Plateau-insights from Cenozoic plate motion models

    USGS Publications Warehouse

    Wells, R.E.

    1989-01-01

    Cenozoic global plate motion models based on a hotspot reference frame may provide a useful framework for analyzing the tectonic evolution of the Solomon Islands convergent margin. A postulated late Miocene collision of the Ontong Java Plateau (OJP) with a NE-facing arc is consistent with the predicted path of the OJP across the Pacific Basin and its Miocene arrival at the trench. Late-stage igneous activity (65-30 Ma) predicted for the OJP as it rode over the Samoan hotspot occurred in correlative stratigraphic sections on Malaita, the supposed accreted flake of OJP in the Solomon Islands arc. Convergence similar to the present velocities between Australia and the Pacific plates was characteristic of the last 43 million years. Prior to 43 Ma Pacific-Australia plate motions were divergent, seemingly at odds with geologic evidence for early Tertiary convergence, particularly in Papua New Guinea. A postulated South Pacific plate may have existed between Australia and the Pacific plate and would have allowed implied northward subduction along the northeastern Australia plate boundary that lasted into the early Eocene. Subsequent reorganization of plate motions in the middle Eocene correlates with middle Eocene marginal basin formation along ridges oblique to the main plate boundary. Cessation of spreading on the Pacific-South Pacific Ridge and its subsequent subduction beneath Asia followed the change in Pacific plate motion at 43 Ma. A trapped remnant of the extinct, NW-trending ridge may still lie beneath the western Philippine Sea. The terminal deformation, metamorphism and ophiolite obduction in the Eocene orogen of the southwest Pacific also correlates with the major change in Pacific plate motion at 43 Ma and the subsequent compression of the dying Eocene arc against outlying continental and oceanic crustal blocks of the Australian plate. The Solomon Islands oceanic basement may represent juxtaposition of oceanic plateaus of the Australian plate beneath overthrust, dismembered ophiolite derived from adjacent marginal basin crust. ?? 1989.

  12. 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.

  13. Toothpaste lava from the Barren Island volcano (Andaman Sea)

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Ray, Jyotiranjan S.; Kumar, Alok; Bhutani, Rajneesh; Awasthi, Neeraj

    2011-04-01

    Toothpaste lava is a basaltic lava flow type transitional between pahoehoe and aa and has been described from Paricutin, Kilauea and Etna volcanoes. Here we describe a spectacular example of toothpaste lava, forming part of a recent (possibly 1994-95) aa flow on the active volcano of Barren Island (Andaman Sea). This flow of subalkalic basalt shows abundant squeeze-ups of viscous toothpasate lava near its entry into the sea. The squeeze-ups are sheets and slabs, up to several meters across and tens of centimeters thick, extruded from boccas. They are often prominently curved, have striated upper surfaces with close-spaced, en echelon linear ridges and grooves, broad wave-like undulations perpendicular to the striations, and sometimes, clefts. Textural, geochemical, and Sr-Nd isotopic data on the squeeze-ups and the exposed aa flow core indicate very crystal-rich, viscous, and isotopically very homogeneous lava. We envisage that a greatly reduced speed of this viscous flow at the coastline, possibly aided by a shallowing of the basal slope, led to lateral spreading of the flow, which caused tension in its upper parts. This, with continued (albeit dwindling) lava supply at the back, led to widespread tearing of the flow surface and extrusion of the squeeze-ups. The larger slabs, while extruding in a plastic condition, curved under their own weight, whereas their surfaces experienced brittle deformation, forming the en echelon grooves. The extruded, detached, and rotated sheets and slabs were carried forward for some distance atop the very slowly advancing aa core, before the flow solidified.

  14. Preliminary analysis of the earthquake (MW 8.1) and tsunami of April 1, 2007, in the Solomon Islands, southwestern Pacific Ocean

    USGS Publications Warehouse

    Fisher, Michael A.; Geist, Eric L.; Sliter, Ray; Wong, Florence L.; Reiss, Carol; Mann, Dennis M.

    2007-01-01

    On April 1, 2007, a destructive earthquake (Mw 8.1) and tsunami struck the central Solomon Islands arc in the southwestern Pacific Ocean. The earthquake had a thrust-fault focal mechanism and occurred at shallow depth (between 15 km and 25 km) beneath the island arc. The combined effects of the earthquake and tsunami caused dozens of fatalities and thousands remain without shelter. We present a preliminary analysis of the Mw-8.1 earthquake and resulting tsunami. Multichannel seismic-reflection data collected during 1984 show the geologic structure of the arc's frontal prism within the earthquake's rupture zone. Modeling tsunami-wave propagation indicates that some of the islands are so close to the earthquake epicenter that they were hard hit by tsunami waves as soon as 5 min. after shaking began, allowing people scant time to react.

  15. Preliminary Geologic Map of Mount Pagan Volcano, Pagan Island, Commonwealth of the Northern Mariana Islands

    USGS Publications Warehouse

    Trusdell, Frank A.; Moore, Richard B.; Sako, Maurice K.

    2006-01-01

    Pagan Island is the subaerial portion of two adjoining Quaternary stratovolcanoes near the middle of the active Mariana Arc, [FAT1]north of Saipan. Pagan and the other volcanic islands that constitute part of the Arc form the northern half of the East Mariana Ridge[FAT2], which extends about 2-4 km above the ocean floor. The > 6-km-deep Mariana Trench adjoins the East Mariana Ridge on the east, and the Mariana Trough, partly filled with young lava flows and volcaniclastic sediment, lies on the west of the Northern Mariana Islands (East Mariana Ridge. The submarine West Mariana Ridge, Tertiary in age, bounds the western side of the Mariana Trough. The Mariana Trench and Northern Mariana Islands (East Mariana Ridge) overlie an active subduction zone where the Pacific Plate, moving northwest at about 10.3 cm/year, is passing beneath the Philippine Plate, moving west-northwest at 6.8 cm/year. Beneath the Northern Mariana Islands, earthquake hypocenters at depths of 50-250 km identify the location of the west-dipping subduction zone, which farther west becomes nearly vertical and extends to 700 km depth. During the past century, more than 40 earthquakes of magnitude 6.5-8.1 have shaken the Mariana Trench. The Mariana Islands form two sub-parallel, concentric, concave-west arcs. The southern islands comprise the outer arc and extend north from Guam to Farallon de Medinilla. They consist of Eocene to Miocene volcanic rocks and uplifted Tertiary and Quaternary limestone. The nine northern islands extend from Anatahan to Farallon de Pajaros and form part of the inner arc. The active inner arc extends south from Anatahan, where volcanoes, some of which are active, form seamounts west of the older outer arc. Other volcanic seamounts of the active arc surmount the East Mariana Ridge in the vicinity of Anatahan and Sarigan and north and south of Farallon de Pajaros. Six volcanoes (Farallon de Pajaros, Asuncion, Agrigan, Mount Pagan, Guguan, and Anatahan) in the northern islands have erupted during the past century, and Ruby Seamount erupted in 1996.

  16. Island-arc magmatic processes beneath South Pagan Volcano, Northern Mariana Islands

    NASA Astrophysics Data System (ADS)

    Marske, J. P.; Trusdell, F. A.; Garcia, M. O.; Pietruszka, A. J.

    2007-12-01

    The island-arc volcanoes that make up the Northern Mariana Islands are among the most historically active stratovolcanoes along the Pacific plate, yet they have been poorly studied due to their remote location and difficult accessibility. One of the least studied areas in the Northern Mariana Islands is Pagan Island, located near the center of the Mariana ridge. Pagan Island consists of two Holocene stratovolcanoes, Mount Pagan and South Pagan. Remarkably little is known about South Pagan including its eruptive history, potential volcanic hazards, and geochemical evolution due to a small population of inhabitants, a short and intermittent recorded history, and few geological studies. There is abundant evidence that eruption of South Pagan could pose significant hazards to both residents of the Northern Mariana Islands and to aircraft flying in the western Pacific. For example, following Mount Pagan's most recent explosive eruption (VEI = 4) in 1981, destructive rain-triggered volcanic debris flows buried large tracts of land, including the site of a village that contained a school, dispensary, church, and power generating buildings. Preliminary field studies in May 2006 by the USGS showed that a full spectrum of hazardous phenomena originated from South Pagan in the past, including pyroclastic flows and surges, caldera collapses, and volcanic debris flows. Two previously unrecognized active fumaroles near the summit of South Pagan were discovered suggesting that potential volcanic hazards currently exist in this area. A majority of the new lava samples are vesicular, clinopyroxene-plagioclase basalts with minor plagioclase xenocrysts and gabbroic xenoliths. The purpose of this study is to understand the compositional history of South Pagan and how it relates to the crustal and mantle magmatic processes beneath the central Northern Mariana Islands. Pb, Sr and Nd isotope ratios, major and trace element abundances, and mineral chemistry were determined and will be presented.

  17. Tree Plantation Systems Influence Nitrogen Retention and the Abundance of Nitrogen Functional Genes in the Solomon Islands.

    PubMed

    Reverchon, Frdrique; Bai, Shahla H; Liu, Xian; Blumfield, Timothy J

    2015-01-01

    Tree mono-plantations are susceptible to soil nutrient impoverishment and mixed species plantations have been proposed as a way of maintaining soil fertility while enhancing biodiversity. In the Solomon Islands, mixed species plantations where teak (Tectona grandis) is inter-planted with a local tree species (Flueggea flexuosa) have been used as an alternative to teak mono-plantations and are expected to increase soil microbial diversity and modify microbial biogeochemical processes. In this study, we quantified the abundance of microbial functional genes involved in the nitrogen (N) cycle from soil samples collected in teak, flueggea, and mixed species plantations. Furthermore, we measured soil properties such as pH, total carbon (C) and total N, stable N isotope composition (?(15)N), and inorganic N pools. Soil pH and ?(15)N were higher under teak than under flueggea, which indicates that intercropping teak with flueggea may decrease bacterial activities and potential N losses. Higher C:N ratios were found under mixed species plantations than those under teak, suggesting an enhancement of N immobilization that would help preventing fast N losses. However, inorganic N pools remained unaffected by plant cover. Inter-planting teak with flueggea in mixed species plantations generally increased the relative abundance of denitrification genes and promoted the enrichment of nosZ-harboring denitrifiers. However, it reduced the abundance of bacterial amoA (ammonia monooxygenase) genes compared to teak mono-plantations. The abundance of most denitrification genes correlated with soil total N and C:N ratio, while bacterial and archeal nitrification genes correlated positively with soil NH4 (+) concentrations. Altogether, these results show that the abundance of bacterial N-cycling functional guilds vary under teak and under mixed species plantations, and that inter-planting teak with flueggea may potentially alleviate N losses associated with nitrification and denitrification and favor N retention. Mixed plantations could also allow an increase in soil C and N stocks without losing the source of income that teak trees represent for local communities. PMID:26733978

  18. Tree Plantation Systems Influence Nitrogen Retention and the Abundance of Nitrogen Functional Genes in the Solomon Islands

    PubMed Central

    Reverchon, Frédérique; Bai, Shahla H.; Liu, Xian; Blumfield, Timothy J.

    2015-01-01

    Tree mono-plantations are susceptible to soil nutrient impoverishment and mixed species plantations have been proposed as a way of maintaining soil fertility while enhancing biodiversity. In the Solomon Islands, mixed species plantations where teak (Tectona grandis) is inter-planted with a local tree species (Flueggea flexuosa) have been used as an alternative to teak mono-plantations and are expected to increase soil microbial diversity and modify microbial biogeochemical processes. In this study, we quantified the abundance of microbial functional genes involved in the nitrogen (N) cycle from soil samples collected in teak, flueggea, and mixed species plantations. Furthermore, we measured soil properties such as pH, total carbon (C) and total N, stable N isotope composition (δ15N), and inorganic N pools. Soil pH and δ15N were higher under teak than under flueggea, which indicates that intercropping teak with flueggea may decrease bacterial activities and potential N losses. Higher C:N ratios were found under mixed species plantations than those under teak, suggesting an enhancement of N immobilization that would help preventing fast N losses. However, inorganic N pools remained unaffected by plant cover. Inter-planting teak with flueggea in mixed species plantations generally increased the relative abundance of denitrification genes and promoted the enrichment of nosZ-harboring denitrifiers. However, it reduced the abundance of bacterial amoA (ammonia monooxygenase) genes compared to teak mono-plantations. The abundance of most denitrification genes correlated with soil total N and C:N ratio, while bacterial and archeal nitrification genes correlated positively with soil NH4+ concentrations. Altogether, these results show that the abundance of bacterial N-cycling functional guilds vary under teak and under mixed species plantations, and that inter-planting teak with flueggea may potentially alleviate N losses associated with nitrification and denitrification and favor N retention. Mixed plantations could also allow an increase in soil C and N stocks without losing the source of income that teak trees represent for local communities. PMID:26733978

  19. High Rates of Asymptomatic, Sub-microscopic Plasmodium vivax Infection and Disappearing Plasmodium falciparum Malaria in an Area of Low Transmission in Solomon Islands

    PubMed Central

    Waltmann, Andreea; Darcy, Andrew W.; Harris, Ivor; Koepfli, Cristian; Lodo, John; Vahi, Ventis; Piziki, David; Shanks, G. Dennis; Barry, Alyssa E.; Whittaker, Maxine; Kazura, James W.; Mueller, Ivo

    2015-01-01

    Introduction Solomon Islands is intensifying national efforts to achieve malaria elimination. A long history of indoor spraying with residual insecticides, combined recently with distribution of long lasting insecticidal nets and artemether-lumefantrine therapy, has been implemented in Solomon Islands. The impact of these interventions on local endemicity of Plasmodium spp. is unknown. Methods In 2012, a cross-sectional survey of 3501 residents of all ages was conducted in Ngella, Central Islands Province, Solomon Islands. Prevalence of Plasmodium falciparum, P. vivax, P. ovale and P. malariae was assessed by quantitative PCR (qPCR) and light microscopy (LM). Presence of gametocytes was determined by reverse transcription quantitative PCR (RT-qPCR). Results By qPCR, 468 Plasmodium spp. infections were detected (prevalence = 13.4%; 463 P. vivax, five mixed P. falciparum/P. vivax, no P. ovale or P. malariae) versus 130 by LM (prevalence = 3.7%; 126 P. vivax, three P. falciparum and one P. falciparum/P. vivax). The prevalence of P. vivax infection varied significantly among villages (range 3.0–38.5%, p<0.001) and across age groups (5.3–25.9%, p<0.001). Of 468 P. vivax infections, 72.9% were sub-microscopic, 84.5% afebrile and 60.0% were both sub-microscopic and afebrile. Local residency, low education level of the household head and living in a household with at least one other P. vivax infected individual increased the risk of P. vivax infection. Overall, 23.5% of P. vivax infections had concurrent gametocytaemia. Of all P. vivax positive samples, 29.2% were polyclonal by MS16 and msp1F3 genotyping. All five P. falciparum infections were detected in residents of the same village, carried the same msp2 allele and four were positive for P. falciparum gametocytes. Conclusion P. vivax infection remains endemic in Ngella, with the majority of cases afebrile and below the detection limit of LM. P. falciparum has nearly disappeared, but the risk of re-introductions and outbreaks due to travel to nearby islands with higher malaria endemicity remains. PMID:25996619

  20. Volcanoes

    MedlinePLUS

    ... Winter Storms & Extreme Cold Space Weather Main Content Volcanoes A volcano is a mountain that opens downward ... most mountains, which are pushed up from below, volcanoes are vents through which molten rock escapes to ...

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

    PubMed

    Peci, Luis Miguel; Berrocoso, Manuel; Fernndez-Ros, Alberto; Garca, Alicia; Marrero, Jos Manuel; Ortiz, Ramn

    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

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

    PubMed Central

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

    2014-01-01

    This paper describes the development of a multi-parameter system for monitoring volcanic activity. The system permits the remote access and the connection of several modules in a network. An embedded ARM™™ processor has been used, allowing a great flexibility in hardware configuration. The use of a complete Linux solution (Debian™) as Operating System permits a quick, easy application development to control sensors and communications. This provides all the capabilities required and great stability with relatively low energy consumption. The cost of the components and applications development is low since they are widely used in different fields. Sensors and commercial modules have been combined with other self-developed modules. The Modular Volcano Monitoring System (MVMS) described has been deployed on the active Deception Island (Antarctica) volcano, within the Spanish Antarctic Program, and has proved successful for monitoring the volcano, with proven reliability and efficient operation under extreme conditions. In another context, i.e., the recent volcanic activity on El Hierro Island (Canary Islands) in 2011, this technology has been used for the seismic equipment and GPS systems deployed, thus showing its efficiency in the monitoring of a volcanic crisis. PMID:24451461

  3. Shallow seismic imaging of flank collapse structures in oceanic island volcanoes: Application to the Western Canary Islands

    NASA Astrophysics Data System (ADS)

    Sanchez, L.; Gonzlez, P.; Tiampo, K. F.

    2013-12-01

    Volcanic flank collapse counts among the many hazards associated with volcanic activity. This type of event involves the mobilization of large volumes, producing debris avalanches. It affects mostly oceanic island volcanoes, involving the potential for tsunami occurrence. Geophysical imaging can illuminate subvolcanic features such as volcano-tectonic structures, magmatic plumbing systems or differences in rock type. The most commonly used geophysical methods are gravity, electromagnetics and seismics. In particular, seismic measurements quantify anomalies in seismic waves propagation velocities and can be used to obtain information on the subsurface arrangement of different materials. In the Western Canary Islands, the Cumbre Vieja volcano in La Palma (Canary Islands) has been proposed to be near the collapse stage. Previous geophysical studies that have been carried out on the flank of the volcano comprise gravity and electromagnetic methods. These types of surveys gather information on the deep structures of the volcano (1-2 km). In this project, we complement previous studies by using seismic methods to investigate the near-surface seismic structure of the Cumbre Vieja fault system (La Palma Island) and the structure of the well-developed San Andres fault system (El Hierro Island). We aim to compare the Cumbre Vieja and San Andres fault systems to infer the degree of maturity of collapse structures. We carried out reflection and refraction seismic surveys in order to image approximately the first 10 meters of the subsurface. We used 24 low frequency (4,5 Hz) geophones as receivers and a sledge hammer as the seismic source. The survey lines were located across visible parts of the fault systems at the Cumbre Vieja volcano and the San Andres fault in El Hierro. Here, we present the survey setup and results from the preliminary analysis of the data.

  4. Magma Differentiation in the Plumbing System of an Alkaline Ocean Island Volcano (Fuerteventura, Canary Island).

    NASA Astrophysics Data System (ADS)

    Tornare, E.; Bussy, F.; Pilet, S.

    2014-12-01

    Magma differentiation and mixing are generally regarded as taking place in magma chambers, sills or reservoirs, while magma stagnates before continuing to ascent or erupt. Here we consider differentiation to occur during magma rise in vertical dykes, as documented in the PX1 pluton, Fuerteventura, which is part of the root-zone of an eroded ocean island volcano. PX1 is a vertically layered cumulative body composed of meter to decameter-wide bands of clinopyroxenites and gabbros, surrounded by a very high-grade contact aureole (ca. 1000C, Hobson et al., 1998). Many clinopyroxenites are characterized by a coarse-grained texture and complexly zoned clinopyroxene crystals. Resorption features and reverse zoning observed in rims are evidence for successive pulses. Percolation of high temperature basaltic melts through the accumulating crystal-rich mush would generate the complexly zoned clinopyroxenes and lead to crystal coarsening. We interpret these coarse-grained clinopyroxenites as crystal-rich magma channels, through which sustained magma fluxes travelled to the surface over a long period of time, thus generating the contact aureole. On the other hand, gabbro bands are interpreted as sluggish magma pulses emplaced in a cooler environment during the waning stages of magmatic activity. We thus propose a model of magma differentiation by dynamic fractionation in dykes throughout magma ascent in the plumbing system of basaltic volcanoes. This model assumes fractional crystallization of continuously rising magmas in vertical channels all along their way to the surface through phenocryst accumulation and crystal-melt interaction processes.

  5. Patterns in thermal emissions from the volcanoes of the Aleutian Islands

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Using AVHRR data 1993-2011 and the Alaska Volcano Observatory's Okmok II Algorithm, the thermal emissions from all volcanoes in the Aleutian Islands were converted from temperature to power emission and examined for periodicity. The emissions were also summed to quantify the total energy released throughout the period. It was found that in the period April 1997 - January 2004 (37% of the period) the power emission from the volcanoes of the island arc declined sharply to constitute just 5.7% of the total power output for the period (138,311 MW), and this was attributable to just three volcanoes: Veniaminof (1.0%), Cleveland (1.5%) and Shishaldin (3.2%). This period of apparent reduced activity contrasts with the periods both before and after and is unrelated to the number of sensors in orbit at the time. What is also evident from the data set is that in terms of overall power emission over this period, the majority of emitted energy is largely attributable to those volcanoes which erupt with regularity (again, Veniaminof [29.7%], Cleveland [17%] and Shishaldin [11.4%]), as opposed to from the relatively few, large scale events (i.e. Reboubt [5.4%], Okmok [8.3%], Augustine [9.7%]; Pavlov [13.9%] being an exception). Sum power emission from volcanoes in the Aleutian Islands (1993-2011)

  6. 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)

  7. Post-eruptive morphological evolution of island volcanoes: Surtsey as a modern case study

    NASA Astrophysics Data System (ADS)

    Romagnoli, C.; Jakobsson, S. P.

    2015-12-01

    Surtsey is a small volcanic island in the Vestmannaeyjar archipelago, off the south coast of Iceland. The eruption leading to the island's emersion lasted for 3.5 yr (1963-1967) while destructive forces have been active for over 50 yr (1963-present-day) during which Surtsey has suffered rapid subaerial and submarine erosion and undergone major morphological changes. Surtsey is a well-documented modern example of the post-eruptive degradational stage of island volcanoes, and has provided the unique opportunity to continuously observe and quantify the effects of intense geomorphic processes. In this paper we focus on coastal and marine processes re-shaping the shoreline and shallow-water portions of the Surtsey complex since its formation and on the related geomorphological record. Analogies with the post-eruptive morphological evolution of recently active island volcanoes at the emerging stage, encompassing different climatic conditions, wave regimes and geological contexts, are discussed.

  8. 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.

  9. Volcanoes.

    ERIC Educational Resources Information Center

    Tilling, Robert I.

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

  10. Mesoscale Eddies in the Solomon Sea

    NASA Astrophysics Data System (ADS)

    Hristova, H. G.; Kessler, W. S.; McWilliams, J. C.; Molemaker, M. J.

    2011-12-01

    Water mass transformation in the strong equatorward flows through the Solomon Sea influences the properties of the Equatorial Undercurrent and subsequent cold tongue upwelling. High eddy activity in the interior Solomon Sea seen in altimetric sea surface height (SSH) and in several models may provide a mechanism for these transformations. We investigate these effects using a mesoscale (4-km resolution) sigma-coordinate (ROMS) model of the Solomon Sea nested in a basin solution, forced by a repeating seasonal cycle, and evaluated against observational data. The model generates a vigorous upper layer eddy field; some of these are apparently shed as the New Guinea Coastal Undercurrent threads through the complex topography of the region, others are independent of the strong western boundary current. We diagnose the scales and vertical structure of the eddies in different parts of the Solomon Sea to illuminate their generation processes and propagation characteristics, and compare these to observed eddy statistics. Hypotheses tested are that the Solomon Sea mesoscale eddies are generated locally by baroclinic instability, that the eddies are shed as the South Equatorial Current passes around and through the Solomon Island chain, that eddies are generated by the New Guinea Coastal Undercurrent, or that eddies occurring outside of the Solomon Sea propagate into the Solomon Sea. These different mechanisms have different implications for the resulting mixing and property fluxes. They also provide different interpretations for SSH signals observed from satellites (e.g., that will be observed by the upcoming SWOT satellite).

  11. Large Scale Failures on Volcanoes of Kurile Islands: the First Data

    NASA Astrophysics Data System (ADS)

    Belousov, A.; Belousova, M.

    2007-12-01

    Investigations of air and space images of volcanoes of the Kurile arc, supplemented by observations from a vessel as well as by on-land field work on several islands, have allowed us to identify 23 active volcanoes with well-preserved horseshoe-shaped scars formed by large-scale edifice failures. Breaches of most of the scars (14 cases) range from 0.5 to 2 km wide, indicating moderate failure volumes - around 1 km3. The two largest scars were 4 km-across (which were formed by failures with volumes about 5 km3) belong to Milne and Sinarka volcanoes. Most of the failures occurred on andesitic volcanoes which dominate in the region. At least 3 volcanoes (Harimkotan, Sinarka and Mendeleev) experienced multiple (3 or more) failures. Only two failures occurred on dominantly basaltic stratovolcanoes (Alaid and Atsonupuri). Most of the collapsed volcanoes of the Kurile arc exhibit strong hydrothermal alteration of rocks inside their horseshoe-shaped scars, and their debris avalanche deposits contain a large proportion of clayey material. This suggests that weakening of rocks composing volcanic edifices caused by hydrothermal alteration played a leading role in gravitational destabilization of the volcanoes. In 50% of the cases, failures were followed by magmatic activity; the horseshoe- shaped craters are partially filled by younger volcanic cones. This indicates that the failure surfaces intersected upper parts of feeding channels of active volcanoes, and the failures may have been triggered by magma intruding into the volcanic edifices. Apart from failures on active volcanoes there are multiple rather large scale (>0,01 km3) failures along sea cliffs of the islands which involved volcanic rocks. These cases are transitional to non-volcanic failures. Debris avalanches of all of the studied failures traveled far beyond the shore line of Okhotskoye Sea or the Pacific Ocean and thus their exact lengths and drop heights are unknown. The debris avalanches obviously generated tsunamis upon entering the sea. The studied failures have Late Pleistocene-Holocene ages; and one historical case failure of Harimkotan volcano on January 8, 1933 with the volume 0.4 km3. The failure generated a tsunami up to 20 m high with 2 reported victims on nearby Onekotan Island. The failure was followed by a strong, 5-day-long Plinian eruption with deposition of pyroclastic flows and subsequent dome growth over several months.

  12. Active submarine volcano sampled

    USGS Publications Warehouse

    Taylor, B.

    1983-01-01

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

  13. 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.

  14. Sheared sheet intrusions as a 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.

    2014-12-01

    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 [Famin and Michon, 2010]. We use 3D numerical models to compare the ability of purely opened sheet intrusions, sheared sheet intrusions, and normal faults to induce flank displacement on basaltic volcanoes (Figure). We assume that shear stress change on fractures which are not normal to a principal stress 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. 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, thus limits to the parameter space which can be further explored through a formal inversion. Applying this procedure to the 1.4 m co-eruptive flank displacement recorded at Piton de la Fournaise in 2007, we find that it probably originated from a shallow eastward-dipping sub-horizontal normal fault.

  15. Deep intrusions, lateral magma transport and related uplift at ocean island volcanoes

    NASA Astrophysics Data System (ADS)

    Klgel, Andreas; Longpr, Marc-Antoine; Garca-Caada, Laura; Stix, John

    2015-12-01

    Oceanic intraplate volcanoes grow by accumulation of erupted material as well as by coeval or discrete magmatic intrusions. Dykes and other intrusive bodies within volcanic edifices are comparatively well studied, but intrusive processes deep beneath the volcanoes remain elusive. Although there is geological evidence for deep magmatic intrusions contributing to volcano growth through uplift, this has rarely been demonstrated by real-time monitoring. Here we use geophysical and petrological data from El Hierro, Canary Islands, to show that intrusions from the mantle and subhorizontal transport of magma within the oceanic crust result in rapid endogenous island growth. Seismicity and ground deformation associated with a submarine eruption in 2011-2012 reveal deep subhorizontal intrusive sheets (sills), which have caused island-scale uplift of tens of centimetres. The pre-eruptive intrusions migrated 15-20 km laterally within the lower oceanic crust, opening pathways that were subsequently used by the erupted magmas to ascend from the mantle to the surface. During six post-eruptive episodes between 2012 and 2014, further sill intrusions into the lower crust and upper mantle have caused magma to migrate up to 20 km laterally, resulting in magma accumulation exceeding that of the pre-eruptive phase. A comparison of geobarometric data for the 2011-2012 El Hierro eruption with data for other Atlantic intraplate volcanoes shows similar bimodal pressure distributions, suggesting that eruptive phases are commonly accompanied by deep intrusions of sills and lateral magma transport. These processes add significant material to the oceanic crust, cause uplift, and are thus fundamentally important for the growth and evolution of volcanic islands. We suggest that the development of such a magma accumulation zone in the lower oceanic crust begins early during volcano evolution, and is a consequence of increasing size and complexity of the mantle reservoir system, and potentially the lithospheric stresses imposed by increasing edifice load.

  16. Geochemistry and solute fluxes of volcano-hydrothermal systems of Shiashkotan, Kuril Islands

    NASA Astrophysics Data System (ADS)

    Kalacheva, Elena; Taran, Yuri; Kotenko, Tatiana

    2015-04-01

    Shiashkotan Island belongs to the Northern Kuril island arc and consists of two joined volcanoes, Sinarka and Kuntomintar, with about 18 km of distance between the summits. Both volcanoes are active, with historic eruptions, and both emit fumarolic gases. Sinarka volcano is degassing through the extrusive dome with inaccessible strong and hot (> 400 °C) fumaroles. A large fumarolic field of the Kuntomintar volcano situated in a wide eroded caldera-like crater hosts many fumarolic vents with temperatures from boiling point to 480 °C. Both volcanoes are characterized by intense hydrothermal activity discharging acid SO4-Cl waters, which are drained to the Sea of Okhotsk by streams. At least 4 groups of near-neutral Na-Mg-Ca-Cl-SO4 springs with temperatures in the range of 50-80 °C are located at the sea level, within tide zones and discharge slightly altered diluted seawater. Volcanic gas of Kuntomintar as well as all types of hydrothermal manifestations of both volcanoes were collected and analyzed for major and trace elements and water isotopes. Volcanic gases are typical for arc volcanoes with 3He/4He corrected for air contamination up to 6.4 Ra (Ra = 1.4 × 10- 6, the air ratio) and δ13C (CO2) within - 10‰ to - 8 ‰ VPDB. Using a saturation indices approach it is shown that acid volcanic waters are formed at a shallow level, whereas waters of the coastal springs are partially equilibrated with rocks at ~ 180 °C. Trace element distribution and concentrations and the total REE depend on the water type, acidity and Al + Fe concentration. The REE pattern for acidic waters is unusual but similar to that found in some acidic crater lake waters. The total hydrothermal discharge of Cl and S from the island associated with volcanic activity is estimated at ca. 20 t/d and 40 t/d, respectively, based on the measurements of flow rates of the draining streams and their chemistry. The chemical erosion of the island by surface and thermal waters is estimated at 27 and 140 ton/km2/year, respectively, which is 2-3 times lower than chemical erosion of tropical volcanic islands.

  17. 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.

  18. The pattern of circumferential and radial eruptive fissures on the volcanoes of Fernandina and Isabela islands, Galapagos

    USGS Publications Warehouse

    Chadwick, W.W., Jr.; Howard, K.A.

    1991-01-01

    Maps of the eruptive vents on the active shield volcanoes of Fernandina and Isabela islands, Galapagos, made from aerial photographs, display a distinctive pattern that consists of circumferential eruptive fissures around the summit calderas and radial fissures lower on the flanks. On some volcano flanks either circumferential or radial eruptions have been dominant in recent time. The location of circumferential vents outside the calderas is independent of caldera-related normal faults. The eruptive fissures are the surface expression of dike emplacement, and the dike orientations are interpreted to be controlled by the state of stress in the volcano. Very few subaerial volcanoes display a pattern of fissures similar to that of the Galapagos volcanoes. Some seamounts and shield volcanoes on Mars morphologically resemble the Galapagos volcanoes, but more specific evidence is needed to determine if they also share common structure and eruptive style. ?? 1991 Springer-Verlag.

  19. Interaction between forest biodiversity and people’s use of forest resources in Roviana, Solomon Islands: implications for biocultural conservation under socioeconomic changes

    PubMed Central

    2014-01-01

    Background In Solomon Islands, forests have provided people with ecological services while being affected by human use and protection. This study used a quantitative ethnobotanical analysis to explore the society–forest interaction and its transformation in Roviana, Solomon Islands. We compared local plant and land uses between a rural village and urbanized village. Special attention was paid to how local people depend on biodiversity and how traditional human modifications of forest contribute to biodiversity conservation. Methods After defining locally recognized land-use classes, vegetation surveys were conducted in seven forest classes. For detailed observations of daily plant uses, 15 and 17 households were randomly selected in the rural and urban villages, respectively. We quantitatively documented the plant species that were used as food, medicine, building materials, and tools. Results The vegetation survey revealed that each local forest class represented a different vegetative community with relatively low similarity between communities. Although commercial logging operations and agriculture were both prohibited in the customary nature reserve, local people were allowed to cut down trees for their personal use and to take several types of non-timber forest products. Useful trees were found at high frequencies in the barrier island’s primary forest (68.4%) and the main island’s reserve (68.3%). Various useful tree species were found only in the reserve forest and seldom available in the urban village. In the rural village, customary governance and control over the use of forest resources by the local people still functioned. Conclusions Human modifications of the forest created unique vegetation communities, thus increasing biodiversity overall. Each type of forest had different species that varied in their levels of importance to the local subsistence lifestyle, and the villagers’ behaviors, such as respect for forest reserves and the semidomestication of some species, contributed to conserving diversity. Urbanization threatened this human–forest interaction. Although the status of biodiversity in human-modified landscapes is not fully understood, this study suggested that traditional human modifications can positively affect biodiversity and that conservation programs should incorporate traditional uses of landscapes to be successful. PMID:24468329

  20. Stratigraphic framework of Holocene volcaniclastic deposits, Akutan Volcano, east-central Aleutian Islands, Alaska

    USGS Publications Warehouse

    Waythomas, C.F.

    1999-01-01

    Akutan Volcano is one of the most active volcanoes in the Aleutian arc, but until recently little was known about its history and eruptive character. Following a brief but sustained period of intense seismic activity in March 1996, the Alaska Volcano Observatory began investigating the geology of the volcano and evaluating potential volcanic hazards that could affect residents of Akutan Island. During these studies new information was obtained about the Holocene eruptive history of the volcano on the basis of stratigraphic studies of volcaniclastic deposits and radiocarbon dating of associated buried soils and peat. A black, scoria-bearing, lapilli tephra, informally named the 'Akutan tephra,' is up to 2 m thick and is found over most of the island, primarily east of the volcano summit. Six radiocarbon ages on the humic fraction of soil A-horizons beneath the tephra indicate that the Akutan tephra was erupted approximately 1611 years B.P. At several locations the Akutan tephra is within a conformable stratigraphic sequence of pyroclastic-flow and lahar deposits that are all part of the same eruptive sequence. The thickness, widespread distribution, and conformable stratigraphic association with overlying pyroclastic-flow and lahar deposits indicate that the Akutan tephra likely records a major eruption of Akutan Volcano that may have formed the present summit caldera. Noncohesive lahar and pyroclastic-flow deposits that predate the Akutan tephra occur in the major valleys that head on the volcano and are evidence for six to eight earlier Holocene eruptions. These eruptions were strombolian to subplinian events that generated limited amounts of tephra and small pyroclastic flows that extended only a few kilometers from the vent. The pyroclastic flows melted snow and ice on the volcano flanks and formed lahars that traveled several kilometers down broad, formerly glaciated valleys, reaching the coast as thin, watery, hyperconcentrated flows or water floods. Slightly cohesive lahars in Hot Springs valley and Long valley could have formed from minor flank collapses of hydrothermally altered volcanic bedrock. These lahars may be unrelated to eruptive activity.

  1. 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.

  2. Petrology of Matthew and Hunter volcanoes, south New Hebrides island arc (southwest Pacific)

    NASA Astrophysics Data System (ADS)

    Maillet, Patrick; Monzier, Michel; Lefevre, Christian

    1986-11-01

    Matthew and Hunter, the two southernmost active volcanoes of the New Hebrides island arc (southwest Pacific) differ markedly from the other (mainly tholeiitic Quaternary volcanoes of this arc. Geodynamically related to the New Hebrides subduction zone, they also lie close to the southern limb of the active expanding ridge of the North Fiji Basin. Both volcanoes are made up of acid, medium-K, calcalkaline orogenic andesites, containing a variety of inclusions (pyroxene- and gabbroic cumulates, as well as doleritic cognate inclusions). This paper presents the first systematic petrographic and chemical study of these volcanics and their inclusions. Trace-element geochemistry and rare-earth element modelling suggest that the two volcanoes developed from successive batches of similar parental magmas, originating from limited partial fusion of garnet peridotite in the mantle wedge. Various degrees of fractional crystallization of these batches led to the formation of three volcanic suites: Hunter (little fractionated), West-Matthew (moderately fractionated) and East-Matthew (highly fractionated). Moreover, on Matthew island, no correlation exists between the degree of fractionation and the eruptive chronology, the youngest edifice (West-Matthew) being less evolved than the older one (East-Matthew).

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

    SciTech Connect

    Mizuno, Tateki; Maeda, Takahisa; 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.

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

    USGS Publications Warehouse

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

    2005-01-01

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

  5. Evidence for two shield volcanoes exposed on the island of Kauai, Hawaii

    USGS Publications Warehouse

    Holcomb, R.T.; Reiners, P.W.; Nelson, B.K.; Sawyer, N.-L.E.

    1997-01-01

    The island of Kauai has always been interpreted as a single shield volcano, but lavas of previously correlated reversed-to-normal magnetic-polarity transitions on opposite sides of the island differ significantly in isotopic composition. Samples from west Kauai have 87Sr/86Sr 18.25; samples from east Kauai have 87Sr/86Sr > 0.7037, ??Nd ??? 6.14, and 206Pb/204Pb < 18.25. Available data suggest that a younger eastern shield grew on the collapsed flank of an older western one.

  6. Volcanoes

    MedlinePLUS

    ... that opens downward to a reservoir of molten rock below the surface of the earth. Unlike most ... from below, volcanoes are vents through which molten rock escapes to the earth’s surface. When pressure from ...

  7. Volcanoes

    MedlinePLUS

    ... About CDC.gov . Natural Disasters and Severe Weather Earthquakes Being Prepared Emergency Supplies Home Hazards Indoor Safety ... Matters What's New Preparation & Planning Disasters & Severe Weather Earthquakes Extreme Heat Floods Hurricanes Landslides Tornadoes Tsunamis Volcanoes ...

  8. Effect of diel activity patterns and harvesting pressure on the diversity and biomass of sea cucumbers in Marovo Lagoon, Solomon Islands.

    PubMed

    Buckius, Christine; Albert, Simon; Tibbetts, Ian; Udy, James

    2010-05-01

    A marked decline in the contribution by Marovo Lagoon to the annual total bêche-de-mer production of the Solomon Islands from 58% in 1989 to 17% in 2003 prompted investigation of their current biomass and diversity. We also assessed changes to critical ecological services and the prospects for population recovery following a fisheries closure. Day time and nocturnal transects revealed a mean abundance of 32.4 (SD = 5.3) low value species per ha (e.g. Holothuria atra, H. edulis, H. coluber and Thelenota anax) and 15.2 (SD = 2.7) high value species per ha (e.g. H. fuscogilva, Actinopyga lecanora, Stichopus hermanni and Thelenota ananas). Following a 17 month closure of the fishery (2005-2007), the abundance of bêche-de-mer was reported by local fisherman to have increased; however, no scientific studies were conducted that can substantiate this community held belief. The current study aimed to document the impact of re-opening the fishery in 2007 and documented a decline in high value species of 9% over a 5 month period following the opening of the fishery, while low value species continued to increase in abundance by 11%, over the same period based on nocturnal surveys. Continued observation of the recovery, post closure, and any subsequent harvest in Marovo will be required to properly understand population dynamics and provide a sustainable harvest plan for bêche-de-mer in the future. PMID:20349313

  9. Effect of Diel Activity Patterns and Harvesting Pressure on the Diversity and Biomass of Sea Cucumbers in Marovo Lagoon, Solomon Islands

    NASA Astrophysics Data System (ADS)

    Buckius, Christine; Albert, Simon; Tibbetts, Ian; Udy, James

    2010-05-01

    A marked decline in the contribution by Marovo Lagoon to the annual total bêche-de-mer production of the Solomon Islands from 58% in 1989 to 17% in 2003 prompted investigation of their current biomass and diversity. We also assessed changes to critical ecological services and the prospects for population recovery following a fisheries closure. Day time and nocturnal transects revealed a mean abundance of 32.4 (SD = 5.3) low value species per ha (e.g. Holothuria atra, H. edulis, H. coluber and Thelenota anax) and 15.2 (SD = 2.7) high value species per ha (e.g. H. fuscogilva, Actinopyga lecanora, Stichopus hermanni and Thelenota ananas). Following a 17 month closure of the fishery (2005-2007), the abundance of bêche-de-mer was reported by local fisherman to have increased; however, no scientific studies were conducted that can substantiate this community held belief. The current study aimed to document the impact of re-opening the fishery in 2007 and documented a decline in high value species of 9% over a 5 month period following the opening of the fishery, while low value species continued to increase in abundance by 11%, over the same period based on nocturnal surveys. Continued observation of the recovery, post closure, and any subsequent harvest in Marovo will be required to properly understand population dynamics and provide a sustainable harvest plan for bêche-de-mer in the future.

  10. Youth research. Naked wire and naked truths: a study of reproductive health risks faced by teenage girls in Honiara, Solomon Islands, November 1997.

    PubMed

    1998-01-01

    A qualitative research project conducted in 1997 in the Solomon Islands used questionnaires, focus groups discussions, and in-depth interviews to gather information on reproductive health risks faced by young, unmarried women in Honiara. In this setting, urbanization and poverty, migration, unemployment, and low levels of education increase the risk for youth of acquiring HIV/AIDS or a sexually transmitted disease (STD). Young women, who must yield to the authority of their male relatives, often have clandestine sexual relationships beginning as early as age 12 and are unable to negotiate safe sex behavior. Commercial sexual exchanges are also on the increase. Sex education is generally confined to secondary schools, although most girls drop-out after primary school. The main source of sex information is the media and friends. While there is concern about adolescent pregnancy rates, contraceptive access is restricted to young, unmarried women. The reaction of a family to an adolescent pregnancy is initial anger and ultimate acceptance. Condom use is low, largely because it is believed that it interferes with sexual pleasure. Because the young women are unable to negotiate safe sex, they are at risk of pregnancy, STDs, and HIV/AIDS. The situation can be improved by creating an enabling environment for young women through policy initiatives, improving knowledge, promoting condom use, providing reproductive health services, and improving communication channels. PMID:12294582

  11. Toward a three-century reconstruction of climate variability from a slow-growing coral in the Western Province, Solomon Islands

    NASA Astrophysics Data System (ADS)

    Maupin, C. R.; Quinn, T. M.; Taylor, F. W.; lin, K.; Shen, C.

    2012-12-01

    Climate variability in the west Pacific warm pool (WPWP), a major heat and moisture source to the atmosphere, is strongly influenced by the El Nio-Southern Oscillation (ENSO). Modeling work has suggested that multi-century scale reconstructions of ENSO variability from the tropical west Pacific may be necessary to fully characterize the nature of the ENSO system. Much of the previous coral-based climate studies have used the fast-growing coral genus Porites, although a few studies have used the long-lived, slow-growing coral genus Diploastrea. Here we present an oxygen isotope time series from a three century long D. heliopora coral from near Olasana Island, Western Province, Solomon Islands (WPSI, 807.92' S, 15654.50' E), a location in the WPWP that experiences significant temperature and salinity anomalies during ENSO events. We first used a forward model to generate a pseudoproxy time series for the Olasana region, utilizing available gridded sea surface temperature (SST) and sea surface salinity (SSS) data spanning 1970-2007. There are strong correlations between predicted and measured coral ?18O, between both monthly (r = 0.84) and monthly anomaly (r = 0.69) records. These results demonstrate that the Olasana D. heliopora coral ?18O record is a robust proxy of local surface ocean conditions. There is also a robust relationship between the Olasana ?18O record and NINO3.4 index of ENSO activity during 1938-2007, which provides confidence that the Olasana ?18O record can be used to characterize the ENSO state in this region back in time. Finally, we present results from near the core bottom (~1700 CE), which provide a first window into a gap of coral-based ENSO reconstructions in the immediate preindustrial (~1700-1850 CE).

  12. The 7-8 August 2008 eruption of Kasatochi Volcano, central Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Waythomas, Christopher F.; Scott, William E.; Prejean, Stephanie G.; Schneider, David J.; Izbekov, Pavel; Nye, Christopher J.

    2010-12-01

    Kasatochi volcano in the central Aleutian Islands erupted unexpectedly on 7-8 August 2008. Kasatochi has received little study by volcanologists and has had no confirmed historical eruptions. The island is an important nesting area for seabirds and a long-term biological study site of the U.S. Fish and Wildlife Service. After a notably energetic preeruptive earthquake swarm, the volcano erupted violently in a series of explosive events beginning in the early afternoon of 7 August. Each event produced ash-gas plumes that reached 14-18 km above sea level. The volcanic plume contained large amounts of SO2 and was tracked around the globe by satellite observations. The cumulative volcanic cloud interfered with air travel across the North Pacific, causing many flight cancelations that affected thousands of travelers. Visits to the volcano in 2008-2009 indicated that the eruption generated pyroclastic flows and surges that swept all flanks of the island, accumulated several tens of meters of pyroclastic debris, and increased the diameter of the island by about 800 m. Pyroclastic flow deposits contain abundant accidental lithic debris derived from the inner walls of the Kasatochi crater. Juvenile material is crystal-rich silicic andesite that ranges from slightly pumiceous to frothy pumice. Fine-grained pyroclastic surge and fall deposits with accretionary lapilli cover the lithic-rich pyroclastic flow deposits and mark a change in eruptive style from episodic explosive activity to more continuous ash emission with smaller intermittent explosions. Pyroclastic deposits completely cover the island, but wave erosion and gully development on the flanks have begun to modify the surface mantle of volcanic deposits.

  13. Whakaari (White Island volcano, New Zealand): Magma-hydrothermal laboratory

    NASA Astrophysics Data System (ADS)

    Lavallee, Yan; Heap, Michael J.; Reuschle, Thierry; Mayer, Klaus; Scheu, Bettina; Gilg, H. Albert; Kennedy, Ben M.; Letham-Brake, Mark; Jolly, Arthur; Dingwell, Donald B.

    2015-04-01

    Whakaari, active andesitic stratovolcano of the Taupo Volcanic Zone (New Zealand), hosts an open, highly reactive hydrothermal system in the amphitheatre of an earlier sector collapse. Its recent volcanic activity is primarily characterized by sequences of steam-driven (phreatic) and phreatomagmatic explosive eruptions, although a lava dome briefly extruded in 2012. The volcano provides a natural laboratory for the study of aggressive fluids on the permeability of the hydrothermal system, on phreatomagmatic volcanism as well as on the volcano edifice structural stability. Here, we present a holistic experimental dataset on the reservoir rocks properties (mineralogy, permeability, seismic velocity) and their response to changes in stress (strength, deformation mechanisms, fragmentation) and temperature (mineralogical breakdown). We show that the advance degree of alteration in the system, nearly replaced all the original rock-forming minerals. This alteration has produced generally weak rocks, which, when subjected to a differential stress, can undergo transition from a dilatant response (brittle) to a compactant response with a mere confining pressure of about 15-20 MPa (corresponding to depth of about 1 km). Thermal stressing experiments reveal that the alteration phases breakdown at 500 °C (alunite) and 700 °C (dehydrated alum and sulphur), generating much weakened skeletal rocks, deteriorated by a mass loss of 20 wt.%, resulting in an increase in porosity and permeability of about 15 vol.% and an order of magnitude, respectively. Novel thermal stressing tests at high-heating rates (<1000 K/min) suggest that the onset of this mineralogical debilitation is pushed to higher temperatures with heating rates, carrying implication for the stability of the reservoir rocks and explosions during magma movement at variable rates in the upper edifice. Rock strength imposes an important control on the stability of volcanic edifices and of the hydrothermal reservoir rocks, especially when considering the high potential energy stored as fluids in these porous rocks. Recent unrest at Whakaari has resulted in the near sudden generation of phreatomagmatic activity. Here, we complete our experimental description of these rocks by discussing the result of rapid decompression experiments on the rocks stoked with supercritical fluids. The results constrain the violence of these steam-driven events and highlight the predisposition of thermally unstable rocks in hydrothermal system to undergo sudden phreatic eruptions.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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 reaching altitudes of 15 to 20 km were observed in satellite data and were preceded by some of the most intense seismicity yet recorded by the Alaska Volcano Observatory (AVO) seismic network. Eruptive products on Kasatochi Island observed on August 22 and 23 consist of pumice-bearing, lithic-rich pyroclastic-flow deposits overlain by a 1-2 m thick sequence of fine- grained pyroclastic-surge, and -fall deposits all exposed at the coastline. These deposits completely blanket Kasatochi Island to a depth of many meters. Pyroclastic flows entered the sea and extended the coastline 300-400 m beyond prominent wave cut cliffs and sea stacks. Tide gauge data from Adak Island, 80 km to the west, indicate a small tsunami with maximum water amplitude of 20 cm, was initiated during the eruption. Kasatochi volcano lacks a real-time seismic monitoring network. Seismic activity was detected by AVO instruments on Great Sitkin Island 40 km to the west, and thus the timing of eruptive events is approximate. The eruption began explosively at 2201 UTC on August 7, and was followed by at least two additional strong eruptive bursts at 0150 UTC and 0435 UTC, August 8. Satellite data show a significant ash cloud associated with the 0435 UTC event followed by at least 14 hours of continuous ash emission. The lack of a strong ash signature in satellite data suggest that the first two plumes were ash poor. Satellite data also show a large emission of SO2 that entered the stratosphere. Correlation of eruptive periods with deposits on the island is not yet possible, but it appears that pyroclastic flows were emplaced during all three explosive events and the surge and fall deposits accumulated during the continuous phase of the third event only. The role of external water is under investigation, and observations on August 22 and 23 indicated several streams flowing from the base of the crater walls into a shallow lake in the bottom of the 1 km2 crater. The surge and fall deposits exposed on Kasatochi Island contain abundant accretionary lapilli indicating water involvement during the emplacement of these deposits. Tephra deposits observed on islands southwest of Kasatochi range in thickness from 6 cm, 30 km from the volcano, to minor amounts on eastern Adak Island, 80 km to the southwest. A fishing boat about 13 km southwest of Kasatochi received about 12 cm of coarse ash to medium lapilli tephra fall. Tephra deposits observed at 5 locations southwest of Kasatochi consist of single beds of normally graded medium to coarse lapilli tephra fall. The lack of recognizable stratigraphic breaks in the tephra deposits suggests that they were the products of a single fall event, likely the third explosion that produced the most ash rich plume.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  17. 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.

  18. 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.

  19. Ground Water in Kilauea Volcano and Adjacent Areas of Mauna Loa Volcano, Island of Hawaii

    USGS Publications Warehouse

    Takasaki, Kiyoshi J.

    1993-01-01

    About 1,000 million gallons of water per day moves toward or into ground-water bodies of Kilauea Volcano from the lavas of Mauna Loa Volcano. This movement continues only to the northern boundaries of the east and southwest rift zones of Kilauea, where a substantial quantity of ground water is deflected downslope to other ground-water bodies or to the ocean. In the western part of Kilauea, the kaoiki fault system, which parallels the southwest rift zone, may be the main barrier to ground-water movement. The diversion of the ground water is manifested in the western part of Kilauea by the presence of large springs at the shore end of the Kaoiki fault system, and in the eastern part by the apparently large flow of unheated basal ground water north of the east rift zone. Thus, recharge to ground water in the rift zones of Kilauea and to the areas to the south of the rift zones may be largely by local rainfall. Recharge from rainfall for all of Kilauea is about 1,250 million gallons per day. Beneath the upper slopes of the Kilauea rift zones, ground-water levels are 2,000 feet or more above mean sea level, or more than 1,000 feet below land surface. Ground-water levels are at these high altitudes because numerous and closely spaced dikes at depth in the upper slopes impound the ground water. In the lower slopes, because the number of dikes decreases toward the surface, the presence of a sufficient number of dikes capable of impounding ground water at altitudes substantially above sea level is unlikely. In surrounding basal ground-water reservoirs, fresh basal ground water floats on seawater and, through a transition zone of mixed freshwater and seawater, discharges into the sea. The hydraulic conductivity of the dike-free lavas ranges from about 3,000 to about 7,000 feet per day. The conductivity in the upper slopes of the rift ranges from about 5 to 30 feet per day and that of the lower slopes of the east rift zone was calculated at about 7,000 feet per day. The occurrence of heated basal water south of the lower east rift zone of Kilauea indicates the movement of a large quantity of geothermally heated ground water southward from the rift zone. There is little indication of similar movement of water from the upper slopes of the east rift zone, and there is no obvious movement of heated water from the lower east rift to the north because of the absence of heated ground water north of the rift zone. A broad range in temperature and chemical composition of geothermally modified ground water indicates several different sources. Four possible sources are (1) cold meteoric water, (2) cold seawater, (3) hydrothermal fluids of meteoric origin, and (4) hydrothermally modified seawater. The chloride-ion to magnesium-ion ratio of ground water indicates whether the water has been geothermally modified. A ratio greater than 15 to 1 generally denotes geothermally modified ground water.

  20. Long-distance lateral magma transport from intra-oceanic island arc volcanoes

    NASA Astrophysics Data System (ADS)

    Ishizuka, O.; Geshi, N.; Kawanabe, Y.; Ogitsu, I.; Tuzino, T.; Nakano, S.; Arai, K.; Sakamoto, I.; Taylor, R. N.; Sano, K.; Yamamoto, T.

    2011-12-01

    Long-distance lateral magma transport in oceanic island arc volcanoes is emerging as a common phenomenon where the regional stress regime is favorable. It should also be recognized as an important factor in the construction and growth of island arcs. In this contribution, we report on recent investigations into the magma plumbing of Izu-Oshima volcano: an active basaltic volcano with an extensive fissure system. Geophysical observations in the Izu-Bonin intra-oceanic island arc indicate that magma is transported long distances laterally from the main basaltic composite volcano. When Miyakejima erupted in 2000, seismic activity migrated about 30km northwestward from the volcanic centre (Geshi et al., 2002). This event is interpreted to reflect northwestward dike injection and propagation from Miyakejima, transporting magma at a depth range between 12 and 20km (Kodaira et al., 2002). We demonstrated that long-distance lateral magma transport also occurred at the Nishiyama volcano on Hachijojima Island using petrological, geochemical and structural studies of satellite vents (Ishizuka et al., 2008). Nishiyama provided evidence for two types of magma transport. In the first type, primitive magma moved laterally NNW for at least 20km in the middle to lower crust (10-20km deep). The other type is characterized by magmas that have experienced differentiation in a shallow magma chamber beneath Nishiyama and have been transported short distances (<5km). The long-distance magma transport seems to be controlled by a regional extensional stress regime, while short distance transport may be controlled by local stress regime affected by the load generated by the main volcanic edifice. Izu-Oshima volcano comprises numerous, subparallel NW-SE trending submarine ridges extending up to 22 km to the NW and SE from the summit of Izu-Oshima. A recent diving survey has revealed that: 1) NW-SE trending ridges are fissures which erupted basaltic spatter and lava flows. 2) Basaltic effusives are petrographically similar among each ridge, while there are noticeable differences between ridges. 3) The ridges are petrographically distinct from interspersed seamounts. These seamounts are identical to the Higashi-Izu-Oki monogenetic volcanoes (HIMV) found across this area of the rear-arc. Geochemically there is a close similarity between the submarine ridges and the corresponding subaerial chains, implying that each chain represents an episode of magma transport away from the main Izu-Oshima edifice. This scenario also explains the overlapping distribution of the HIMV and NW-SE chains which have clearly distinct magma sources. HIMV appear to be fed by an "in-situ" source, while the NW-SE chains are fed by lateral magma transport from the Izu-Oshima plumbing system. Unlike the Nishiyama volcano, Izu-Oshima does not show a compositional variation along the length of the volcanic chains, and has no evidence of any primitive magmas. Hence, the magma transport from Izu-Oshima seems to occur from a shallow crustal magma chamber where extensive crystal fractionation and plagioclase accumulation has taken place.

  1. Volcano-hydrothermal system of Ebeko volcano, Paramushir, Kuril Islands: Geochemistry and solute fluxes of magmatic chlorine and sulfur

    NASA Astrophysics Data System (ADS)

    Kalacheva, Elena; Taran, Yuri; Kotenko, Tatiana; Hattori, Keiko; Kotenko, Leonid; Solis-Pichardo, Gabriela

    2016-01-01

    Ebeko volcano at the northern part of Paramushir Island in the Kuril island arc produces frequent phreatic eruptions and relatively strong fumarolic activity at the summit area ~ 1000 m above sea level (asl). The fumaroles are characterized by low-temperature, HCl- and S-rich gas and numerous hyper-acid pools (pH < 1) without drains. At ~ 550 m asl, in the Yurieva stream canyon, many hot (up to 87 °C) springs discharge ultra-acidic (pH 1-2) SO4-Cl water into the stream and finally into the Sea of Okhotsk. During quiescent stages of degassing, these fumaroles emit 1000-2000 t/d of water vapor, < 20 t/d of SO2 and < 5 t/d of HCl. The measurement of acidic hot Yurieva springs shows that the flux of Cl and S, 60-80 t/d each, is independent on the volcanic activity in the last two decades. Such high flux of Cl is among the highest ever measured in a volcano-hydrothermal system. Oxygen and hydrogen isotopic composition of water and Cl concentration for Yurieva springs show an excellent positive correlation, indicating a mixing between meteoric water and magmatic vapor. In contrast, volcanic gas condensates of Ebeko fumaroles do not show a simple mixing trend but rather a complicated data suggesting evaporation of the acidic brine. Temperatures calculated from gas compositions and isotope data are similar, ranging from 150 to 250 °C, which is consistent with the presence of a liquid aquifer below the Ebeko fumarolic fields. Saturation indices of non-silicate minerals suggest temperatures ranging from 150 to 200 °C for Yurieva springs. Trace elements (including REE) and Sr isotope composition suggest congruent dissolution of the Ebeko volcanic rocks by acidic waters. Waters of Yurieva springs and waters of the summit thermal fields (including volcanic gas condensates) are different in Cl/SO4 ratios and isotopic compositions, suggesting complicated boiling-condensation-mixing processes.

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

    NASA Astrophysics Data System (ADS)

    Padrn, Eleazar; Prez, Nemesio M.; Rodrguez, Ftima; Melin, Gladys V.; Hernndez, Pedro A.; Sumino, Hirochika; Padilla, Germn; Barrancos, Jos; Dionis, Samara; Notsu, Kenji; Calvo, David

    2015-04-01

    La Palma Island, the fifth longest (706 km2) and the second in elevation (2,423 m asl) of the Canary Islands, is located at the northwestern extreme of the archipelago. Volcanic activity in the last 123 ka has taken place exclusively at the southern part of the island, where Cumbre Vieja volcano, the most active basaltic volcano in the Canaries, has been constructed. Cumbre Vieja includes a main north-south rift zone 20 km long up to 1,950 m in elevation, and covers 220 km2 with vents located also at the northwest and northeast. Nowadays there are no visible gas emission from fumaroles or hot springs at Cumbre Vieja. For this reason, diffuse CO2 degassing studies may provide important information about subsurface magma movement. Since diffuse CO2 emission rate may increase extraordinarily before a volcanic eruption, it is very important to map surface CO2 efflux anomalies and determine the total output of this gas prior to volcanic activity, in order to have a better understanding during future volcanic events. This study report the results of 13 soil CO2 efflux surveys at Cumbre Vieja volcano. 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 2,442 g m-2 d-1, with the highest values observed in the south, where the last volcanic eruption took place (Tenegua, 1971). Isotopic analyses of soil gas carbon dioxide suggest an organic origin as the main contribution to the CO2 efflux, with a very slight magmatic degassing being observed at the southern part of the volcano. Total CO2 emission rates showed a high temporal variability, ranging between 320 and 1,544 t d-1 and averaging 1,147 t d-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 similarity observed in the estimates rates of diffuse CO2 emission make them an effective surveillance tool for Cumbre Vieja volcano like it has been observed at other volcanic areas.

  3. 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.

  4. 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

  5. Tetrodotoxin and Its Analogues in the Pufferfish Arothron hispidus and A. nigropunctatus from the Solomon Islands: A Comparison of Their Toxin Profiles with the Same Species from Okinawa, Japan.

    PubMed

    Puilingi, Clyde Gorapava; Kudo, Yuta; Cho, Yuko; Konoki, Keiichi; Yotsu-Yamashita, Mari

    2015-09-01

    Pufferfish poisoning has not been well documented in the South Pacific, although fish and other seafood are sources of protein in these island nations. In this study, tetrodotoxin (TTX) and its analogues in each organ of the pufferfish Arothron hispidus and A. nigropunctatus collected in the Solomon Islands were investigated using high resolution LC-MS. The toxin profiles of the same two species of pufferfish from Okinawa, Japan were also examined for comparison. TTXs concentrations were higher in the skin of both species from both regions, and relatively lower in the liver, ovary, testis, stomach, intestine, and flesh. Due to higher TTX concentrations (51.0 and 28.7 g/g at highest) detected in the skin of the two species from the Solomon Islands (saxitoxin was <0.02 g/g), these species should be banned from consumption. Similar results were obtained from fish collected in Okinawa, Japan: TTX in the skin of A. hispidus and A. nigropunctatus were 12.7 and 255 g/g, respectively, at highest, and saxitoxin was also detected in the skin (2.80 g/g at highest) and ovary of A. hispidus. TTX, 5,6,11-trideoxyTTX (with its 4-epi form), and its anhydro forms were the most abundant, and 11-oxoTTX was commonly detected in the skin. PMID:26343722

  6. Tetrodotoxin and Its Analogues in the Pufferfish Arothron hispidus and A. nigropunctatus from the Solomon Islands: A Comparison of Their Toxin Profiles with the Same Species from Okinawa, Japan

    PubMed Central

    Gorapava Puilingi, Clyde; Kudo, Yuta; Cho, Yuko; Konoki, Keiichi; Yotsu-Yamashita, Mari

    2015-01-01

    Pufferfish poisoning has not been well documented in the South Pacific, although fish and other seafood are sources of protein in these island nations. In this study, tetrodotoxin (TTX) and its analogues in each organ of the pufferfish Arothron hispidus and A. nigropunctatus collected in the Solomon Islands were investigated using high resolution LC-MS. The toxin profiles of the same two species of pufferfish from Okinawa, Japan were also examined for comparison. TTXs concentrations were higher in the skin of both species from both regions, and relatively lower in the liver, ovary, testis, stomach, intestine, and flesh. Due to higher TTX concentrations (51.0 and 28.7 µg/g at highest) detected in the skin of the two species from the Solomon Islands (saxitoxin was <0.02 µg/g), these species should be banned from consumption. Similar results were obtained from fish collected in Okinawa, Japan: TTX in the skin of A. hispidus and A. nigropunctatus were 12.7 and 255 µg/g, respectively, at highest, and saxitoxin was also detected in the skin (2.80 µg/g at highest) and ovary of A. hispidus. TTX, 5,6,11-trideoxyTTX (with its 4-epi form), and its anhydro forms were the most abundant, and 11-oxoTTX was commonly detected in the skin. PMID:26343722

  7. Ten years of satellite observations reveal highly variable sulphur dioxide emissions at Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    McCormick, Brendan; Popp, Christoph; Andrews, Benjamin; Cottrell, Elizabeth

    2015-07-01

    Satellite remote sensing enables continuous multiyear observations of volcanic activity in remote settings. Anatahan (Mariana Islands) is a remote volcano in the western North Pacific. Available ground-based measurements of sulphur dioxide (SO2) gas emissions at Anatahan place it among thelargest volcanic SO2 sources worldwide. These ground-based measurements, however, are restricted to eruptive intervals. Anatahan's activity since 2003 has been dominated temporally by prolonged periods of quiescence. Using 10 years of satellite observations from OMI, AIRS, SCIAMACHY, and GOME-2, we report highly variable SO2 emissions within and between eruptive and quiescent intervals at Anatahan. We find close correspondence between levels of activity reported at the volcano and levels of SO2 emissions detected from space. Eruptive SO2 emission rates have a mean value of 6400 t d-1, but frequently are in excess of 20,000 t d-1. Conversely, SO2 emissions during quiescent intervals are below the detection limit of space-based sensors and therefore are not likely to exceed 300 t d-1. We show that while Anatahan occupies a quiescent state for 85% of the past 10 years, only 15% of total SO2 emissions over this interval occur during quiescence, with the remaining 85% released in short duration but intense syn-eruptive degassing. We propose that the integration of multiyear satellite data sets and activity histories are a powerful complement to targeted ground-based campaign measurements in better describing the long-term degassing behavior of remote volcanoes.

  8. Oligocene to Recent tectonic history of the Central Solomon intra-arc basin as determined from marine seismic reflection data and compilation of onland geology

    NASA Astrophysics Data System (ADS)

    Cowley, Shane; Mann, Paul; Coffin, M. F.; Shipley, Thomas H.

    2004-10-01

    Systematic analysis of a grid of 3450 km of multichannel seismic reflection lines from the Solomon Islands constrains the late Tertiary sedimentary and tectonic history of the Solomon Island arc and its convergent interaction with the Cretaceous Ontong Java oceanic plateau (OJP). The OJP, the largest oceanic plateau on Earth, subducted beneath the northern edge of the Solomon arc in the late Neogene, but the timing and consequences of this obliquely convergent event and its role in the subduction polarity reversal process remain poorly constrained. The Central Solomon intra-arc basin (CSB), which developed in Oligocene to Recent time above the Solomon arc, provides a valuable record of the tectonic environment prior to and accompanying the OJP convergent event and the subsequent arc polarity reversal. Recognition of regionally extensive stratigraphic sequenceswhose ages can be inferred from marine sedimentary sections exposed onland in the Solomon Islandsindicate four distinct tectonic phases affecting the Solomon Island arc. Phase 1: Late Oligocene-Late Miocene rifting of the northeast-facing Solomon Island arc produced basal, normal-fault-controlled, asymmetrical sequences of the CSB; the proto-North Solomon trench was probably much closer to the CSB and is inferred to coincide with the trace of the present-day Kia-Kaipito-Korigole (KKK) fault zone; this protracted period of intra-arc extension shows no evidence for interruption by an early Miocene period of convergent "soft docking" of the Ontong Java Plateau as proposed by previous workers. Phase 2: Late Miocene-Pliocene oblique convergence of the Ontong Java Plateau at the proto-North Solomon trench (KKK fault zone) and folding of the CSB and formation of the Malaita accretionary prism (MAP); the highly oblique and diachronous convergence between the Ontong Java plateau and the Solomon arc terminates intra-arc extension first in the southeast (Russell subbasin of the CSB) during the Late Miocene and later during the Pliocene in the northwest (Shortland subbasin of the CSB); folds in the CSB form by inversion of normal faults formed during Phase 1; Phinney et al. [Sequence stratigraphy, structural style, and age of deformation of the Malaita accretionary prism (Solomon arc-Ontong Java Plateau convergent zone)] show a coeval pattern of southeast to northwest younging in folding and faulting of the MAP. Phase 3: Late Pliocene-early Pleistocene arc polarity reversal and subduction initiation at the San Cristobal trench. Effects of this event in the CSB include the formation of a chain of volcanoes above the subducting Australia plate at the San Cristobal trench, the formation of the broad synclinal structure of the CSB with evidence for truncation at the uplifted flanks, and widespread occurrence of slides and "seismites" (deposits formed by seismic shaking). Phase 4: Pleistocene to Recent continued shortening and synclinal subsidence of the CSB. Continued Australia-Pacific oblique plate convergence has led to deepening of the submarine, elongate basin axis of the synclinal CSB and uplift of the dual chain of the islands on its flanks.

  9. Shield volcanoes of Marie Byrd Land, West Antarctic rift: oceanic island similarities, continental signature, and tectonic controls

    NASA Astrophysics Data System (ADS)

    LeMasurier, Wesley

    2013-06-01

    The Marie Byrd Land volcanic province is largely defined by 18 large (up to ~1,800 km3) alkaline shield volcanoes, each surmounted by a summit section of varied felsic rocks dominated by trachytic flows. They are distributed over a 500 × 800-km block-faulted dome within the West Antarctic rift. The basement contact of volcanic sections is ~500 masl at one site and 3,000 mbsl at another, 70 km away, which illustrates the scale of block faulting but complicates an understanding of volcanic structure. Furthermore, the continental ice sheet buries 16 volcanoes to progressively greater heights inland. However, five are sufficiently exposed to allow meaningful comparisons with alkaline oceanic island volcanoes; these comparisons are used as a guide to estimate the structure of Marie Byrd Land volcanoes. The type example for this study is Mt. Murphy, the most completely exposed volcano. It consists of a 1,400-m section of alkaline basalt overlain by trachyte and benmoreite flows that make up ~7-13 % of the volcano volume. In gross structure and composition, Mt. Murphy is similar to Gran Canaria volcano, Canary Islands, but the percent of felsic rock may be three times that of Gran Canaria, if the estimate is approximately correct. Departures from the oceanic island example are believed to represent the imprint of the Marie Byrd Land lithosphere and tectonic environment on volcano evolution. These include a lack of order in the sequence of felsic rock types, lack of progression toward more silica undersaturated compositions with time, absence of a highly undersaturated mafic resurgent stage, and perhaps, a relatively large volume of felsic rock.

  10. Upper Mantle Magma Storage and Transport Beneath the Miocene Teno Volcano, Tenerife (Canary Islands)

    NASA Astrophysics Data System (ADS)

    Longpré, M.; Troll, V. R.; Hansteen, T. H.

    2007-12-01

    The nature and dynamics of magma plumbing systems are key variables to the understanding of overlying volcanic edifices. With the exception of a few intensely studied localities, these variables are typically unconstrained at volcanoes around the world. Where attempted, studies of magma storage and transport reveal complex plumbing geometries, for a range of geological settings, indicating that assumptions of shallow, spherical-elliptical magma chambers are often oversimplified. At the highly active, basaltic shield-volcanoes, geophysical monitoring is an effective tool to investigate plumbing system geometries. In the Canary Islands, however, the low eruption frequency results in poor deformation and volcano-seismic data sets and, hence, volcanologists have to rely on alternative methods to study the magma plumbing system of Canarian volcanoes. We use clinopyroxene-liquid thermobarometry [Putirka et al. 1996, Contrib. Mineral. Petrol.], aided by petrography and mineral major element chemistry, to reconstruct the magma plumbing system of the late Miocene Teno shield-volcano, Tenerife. Thin section observations show that the numerous clinopyroxene phenocrysts display darker coloured outer rims, which commonly host acicular apatite microcrystals and sometimes form dentritic protrusions. This is coupled with steep normal Fe-Mg zoning and drastic TiO2 enrichment. Supported by similar Fe-Mg zonations in olivine, this suggests that these rims formed due to decompression induced crystallisation upon rapid magma ascent and accompanying degassing and undercooling. This process took place under disequilibrium conditions, implying that clinopyroxene rim compositions may not always be suitable for thermobarometric investigations. On the other hand, clinopyroxene compositions excluding the outer rims generally appear to be in chemical equilibrium with the melt. Thermobarometry indicates that clinopyroxene crystallisation occurred in the uppermost mantle, mostly from 20 to 40 km depth. The interval between the brittle- ductile transition and the crust-mantle boundary thus appears to provide an efficient magma trap, supporting the concept of progressive magmatic underplating in the Canary Archipelago. The combination of careful sampling strategy, petrography, mineral chemistry and clinopyroxene thermobarometry is a promising tool for investigations of magma plumbing systems at basalt-erupting volcanoes.

  11. 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.

  12. Using volcanic tremor for eruption forecasting at White Island volcano (Whakaari), New Zealand

    NASA Astrophysics Data System (ADS)

    Chardot, Lauriane; Jolly, Arthur D.; M. Kennedy, Ben; Fournier, Nicolas; Sherburn, Steven

    2015-09-01

    Eruption forecasting is a challenging task because of the inherent complexity of volcanic systems. Despite remarkable efforts to develop complex models in order to explain volcanic processes prior to eruptions, the material Failure Forecast Method (FFM) is one of the very few techniques that can provide a forecast time for an eruption. However, the method requires testing and automation before being used as a real-time eruption forecasting tool at a volcano. We developed an automatic algorithm to issue forecasts from volcanic tremor increase episodes recorded by Real-time Seismic Amplitude Measurement (RSAM) at one station and optimised this algorithm for the period August 2011-January 2014 which comprises the recent unrest period at White Island volcano (Whakaari), New Zealand. A detailed residual analysis was paramount to select the most appropriate model explaining the RSAM time evolutions. In a hindsight simulation, four out of the five small eruptions reported during this period occurred within a failure window forecast by our optimised algorithm and the probability of an eruption on a day within a failure window was 0.21, which is 37 times higher than the probability of having an eruption on any day during the same period (0.0057). Moreover, the forecasts were issued prior to the eruptions by a few hours which is important from an emergency management point of view. Whereas the RSAM time evolutions preceding these four eruptions have a similar goodness-of-fit with the FFM, their spectral characteristics are different. The duration-amplitude distributions of the precursory tremor episodes support the hypothesis that several processes were likely occurring prior to these eruptions. We propose that slow rock failure and fluid flow processes are plausible candidates for the tremor source of these episodes. This hindsight exercise can be useful for future real-time implementation of the FFM at White Island. A similar methodology could also be tested at other volcanoes even if only a limited network is available.

  13. Relationship between two Solomon Islands Earthquakes in 2007 (M8.1), 2010 (M7.1), and Seismic Gap along the Subduction Zone, Revealed by ALOS/PALSAR

    NASA Astrophysics Data System (ADS)

    Miyagi, Y.; Ozawa, T.

    2010-12-01

    The Solomon Islands are located in the southwest of the Pacific Ocean. The Australian, Woodlark, and Solomon Sea plates subduct toward the northeast beneath the Pacific plate. Interaction among these four plates cause complicated tectonics around the Solomon Islands, and have caused interplate earthquakes in the subduction zone (e.g. Lay and Kanamori, 1980; Xu and Schwarts, 1993). On April 1, 2007 (UTC), an M8.1 interplate earthquake occurred in the subduction zone between the Pacific Plate and the Australian Plate. This earthquake was accompanied by a large tsunami and caused considerable damage in the area. The Japan Aerospace Exploration Agency (JAXA) carried out emergency observations using the Phased Array type L-band Synthetic Aperture Rader (PALSAR) installed on Advanced Land Observing Satellite (ALOS), and detected more than 2m of maximum displacement using differential interferometric SAR (DInSAR) technique. Miyagi et al. (2009) estimated a slip distribution of the seismic fault mainly from the PALSAR/DInSAR data and suggested that most of a seismic gap was filled by the 2007 events, but a small seismic gap connecting to an Mw7.0-sized earthquake still remained. On January 3, 2010, an M7.1 earthquake occurred in the vicinity of the remnant seismic gap. ALOS/PALSAR observed epicentral area both before and after the event, and detected crustal deformation associated with the earthquake. We inferred fault model using the PALSAR/DInSAR data and concluded that the 2010 event was the supposed thrust earthquake filling the remnant seismic gap. A distribution of coulomb failure stress change in the epicentral area after the 2007 event suggested the possibility that the 2010 event was triggered by the 2007 earthquake.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Sakurajima volcano is the Quaternary post-caldera volcano of Aira caldera, which was caused by the eruption of huge amount of silicic pyroclastics, situated on Ryukyu arc, southern Kyushu Island, Japan. This volcano is quite active, so it can be considered that the preparation of next caldera-forming eruption with huge amount of silicic magma is proceeding. It is, therefore, expected that the investigation of magma genesis of Sakurajima volcano give us information for the mechanism generating huge amount of silicic magma, which cause the caldera formation. We analyzed major and trace elements with Sr, Nd and Pb isotopic compositions of volcanic rocks from Sakurajima volcano. We sampled (ol) - opx - cpx - pl andesite and dacite from almost all the volcanic units defined by Fukuyama and Ono (1981). In addition to Sakurajima samples, we also studied basaltic rocks erupted at pre-caldera stage of the Aira caldera to estimate the primary magma of Sakurajima volcano. Major and trace element variations generally show linear trends on the Harker diagrams, with the exception of P2O5 and TiO2. Based on the trend of P2O5 vs.SiO2, we divided studied samples low-P (P2O5 < 0.15 wt. %) and high-P (P2O5 > 0.15 wt. %) groups and these groups also display two distinct trends on TiO2-SiO2 diagram. The composition of trace elements shows typical island arc character as depletion of Nb and enrichments of Rb, K and Pb, suggesting addition of aqueous fluids to the mantle wedge. The Zr and Nb concentrations make a liner trend (Zr/Nb = 27) and this trend across from tend of MORB (Zr/Nb = 35) to that of crustal materials (Zr/Nb=17). The Sr, Nd and Pb isotopic compositions broadly plot to on the mixing curve connecting MORB-type mantle and sediments of the Philippine Sea Plate, indicating that the primary magma was generated by partial melting of MORB-type mantle wedge, which was hydrated with fluids derived from the subducted Philippine Sea sediments. But we found that our data plot apart from the mixing curve to the direction of being more radiogenic when we observe in more detail. This observation supports our conclusion that the crustal materials contribute the magma genesis of Sakurajima volcano emphasized from Zr/Nb ratios. Low-P and high-P groups show different trends of SiO2, P2O5, TiO2 concentrations and 87Sr/86Sr ratios relative to plagioclase modal abundances. The high-P group samples show continuous trends, and their 87Sr/86Sr ratios increase with decreasing plagioclase, representing simple AFC process. The SiO2 content of low-P group rapidly increases from 63 to 66 wt. % at the modal abundance of pl is nearly 20 vol. %. The Sr isotope ratios of low-P group with < 20 vol. % of pl are obviously high (87Sr/86Sr = 0.70556 to 0.70569) compared to those of high-P group (87Sr/86Sr = 0.705136 to 0.705285). From these observations, we conclude that the rapid increase of SiO2 with high 87Sr/87Sr ratio infer involvement of crustal materials to the magma chamber, in which the ACF process is proceeding.

  15. Seismic vulnerability of dwellings at Sete Cidades Volcano (S. Miguel Island, Azores)

    NASA Astrophysics Data System (ADS)

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

    2006-01-01

    Since the settlement of S. Miguel Island (Azores), in the XV century, several earthquakes caused important human losses and severe damages on the island. Sete Cidades Volcano area, located in the westernmost part of the island, was attained by strong seismic crises of tectonic and volcanic origin and major events reached a maximum historical intensity of IX (European Macroseismic Scale 1998) in this zone. Aiming to evaluate the impact of a future major earthquakes, a field survey was carried out in ten parishes of Ponta Delgada County, located on the flanks of Sete Cidades volcano and inside it is caldera. A total of 7019 buildings were identified, being 4351 recognized as dwellings. The total number of inhabitants in the studied area is 11429. In this work, dwellings were classified according to their vulnerability to earthquakes (Classes A to F), using the structure types table of the EMS-98, adapted to the types of constructions made in the Azores. It was concluded that 76% (3306) of the houses belong to Class A, and 17% (740) to Class B, which are the classes of higher vulnerability. If the area is affected by a seismic event with intensity IX it is estimated, that 57% (2480) to 77% (3350) of the dwellings will partially or totally collapse and 15% (652) to 25% (1088) will need to be rehabilitated. In this scenario, considering the average of inhabitants per house for each parish, 82% (9372) to 92% (10515) of the population will be affected. The number of deaths, injured and dislodged people will pose severe problems to the civil protection authorities and will cause social and economic disruption in the entire archipelago.

  16. The eruption of Mount Pagan volcano, Mariana Islands, 15 May 1981

    NASA Astrophysics Data System (ADS)

    Banks, Norman G.; Koyanagi, Robert Y.; Sinton, John M.; Honma, Kenneth T.

    1984-10-01

    A major explosive eruption occurred 15 May 1981 at Mount Pagan Volcano, the larger of two historic eruptive centers on Pagan Island, Mariana Islands. The eruption was preceded by increased numbers of locally felt earthquakes beginning in late March or early April and by new ground cracks, new sublimates, and increased gas emissions. A swarm of felt earthquakes began at 0745h (local time = UCT+10 hours) 15 May, and at 0915 h, closely following a loud sonic boom, a strong plinian column issued from the volcano. The high-altitude ash cloud (at least 13.5 km) travelled south-southeast, but ash and scoria deposits were thickest (> 2 m) in the NW sector of the island because of the prevailing low-altitude southeasterly winds. The early activity of 15 May probably involved magmatic eruption along a fissure system oriented about N10E. However, the eruption became hydromagmatic, possibly within minutes, and was largely restricted to three long-lived vents. The northernmost of these built a substantial new scoria-ash cinder cone. Flows and air-fall deposits, consisting almost entirely of juvenile material, exceeded 105 10 6 m 3 in volume (75 10 6 m 3 of magma) on land and at least 70-100 60 6 m 3 at sea. An unknown volume was carried away by stratospheric winds. Lithic blocks and juvenile bombs as large as 1 m in diameter were thrown more than 2 km from the summit, and evidence for base-surge was observed in restricted corridors as low as 200 m elevation on the north and south slopes of the volcano. Neither of these events resulted in serious injuries to the 54 residents of the island, nor did the eruption produce serious chemical hazards in their water supply. Weak eruptions occurred during the ensuing month, and some of these were monitored by ground observations, seismic monitoring, and deformation studies. Precursory seismicity and possibly deformation occurred with some of the observed eruptions. More vigorous eruptions were reported by visiting residents in late 1981 and early 1982, but these were of lesser magnitude than the 15 May 1981 event. The 15 May lava is predominantly aa and ranges from 3 to > 30 m in thickness. In composition, it is a high-alumina basalt with small (< 1 mm long) phenocrysts of plagioclase and clinopyroxene (7%) that is more or less typical of basalt of the northern Marianas volcanoes. It contains slightly more SiO 2 (52%), K 2O, TiO 2, and less Al 2O 3 and CaO than does the basalt of the last eruptive event of Mount Pagan Volcano in 1925. Gas analyses indicate that a large portion of air was introduced into the vent system through the porous volcanic edifice and that the carbon gases were not in equilibrium with the magma or each other.

  17. The eruption of Mount Pagan volcano, Mariana Islands, 15 May 1981

    USGS Publications Warehouse

    Banks, N.G.; Koyanagi, R.Y.; Sinton, J.M.; Honma, K.T.

    1984-01-01

    A major explosive eruption occurred 15 May 1981 at Mount Pagan Volcano, the larger of two historic eruptive centers on Pagan Island, Mariana Islands. The eruption was preceded by increased numbers of locally felt earthquakes beginning in late March or early April and by new ground cracks, new sublimates, and increased gas emissions. A swarm of felt earthquakes began at 0745h (local time = UCT+10 hours) 15 May, and at 0915 h, closely following a loud sonic boom, a strong plinian column issued from the volcano. The high-altitude ash cloud (at least 13.5 km) travelled south-southeast, but ash and scoria deposits were thickest (> 2 m) in the NW sector of the island because of the prevailing low-altitude southeasterly winds. The early activity of 15 May probably involved magmatic eruption along a fissure system oriented about N10??E. However, the eruption became hydromagmatic, possibly within minutes, and was largely restricted to three long-lived vents. The northernmost of these built a substantial new scoria-ash cinder cone. Flows and air-fall deposits, consisting almost entirely of juvenile material, exceeded 105 ?? 106 m3 in volume (75 ?? 106 m3 of magma) on land and at least 70-100 ?? 606 m3 at sea. An unknown volume was carried away by stratospheric winds. Lithic blocks and juvenile bombs as large as 1 m in diameter were thrown more than 2 km from the summit, and evidence for base-surge was observed in restricted corridors as low as 200 m elevation on the north and south slopes of the volcano. Neither of these events resulted in serious injuries to the 54 residents of the island, nor did the eruption produce serious chemical hazards in their water supply. Weak eruptions occurred during the ensuing month, and some of these were monitored by ground observations, seismic monitoring, and deformation studies. Precursory seismicity and possibly deformation occurred with some of the observed eruptions. More vigorous eruptions were reported by visiting residents in late 1981 and early 1982, but these were of lesser magnitude than the 15 May 1981 event. The 15 May lava is predominantly aa and ranges from 3 to > 30 m in thickness. In composition, it is a high-alumina basalt with small (< 1 mm long) phenocrysts of plagioclase and clinopyroxene (7%) that is more or less typical of basalt of the northern Marianas volcanoes. It contains slightly more SiO2 (52%), K2O, TiO2, and less Al2O3 and CaO than does the basalt of the last eruptive event of Mount Pagan Volcano in 1925. Gas analyses indicate that a large portion of air was introduced into the vent system through the porous volcanic edifice and that the carbon gases were not in equilibrium with the magma or each other. ?? 1984.

  18. 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)

  19. Magma storage and underplating beneath Cumbre Vieja volcano, La Palma (Canary Islands)

    NASA Astrophysics Data System (ADS)

    Klgel, Andreas; Hansteen, Thor H.; Galipp, Karsten

    2005-07-01

    We have conducted a barometric study of basaltic lavas and mafic to ultramafic xenoliths from Cumbre Vieja volcano (La Palma) in order to reconstruct magma storage, plumbing and related intrusive island growth. The samples were collected both along the volcano's rift zone and from its subaerial and submarine flanks up to 30 km off the rift axis. Clinopyroxene-melt barometry of lavas yields a well-defined pressure range of 410-770 MPa (average 600 MPa) and shows no systematic variation with sample locality. This pressure range reflects a major fractionation level at ca. 15-26 km depth, within the uppermost mantle, where phenocrysts and melt last equilibrated. In contrast, microthermometry of CO 2-dominated fluid inclusions in phenocrysts and xenoliths gives pressure estimates of 240 to 470 MPa (average 330 MPa), within the lower oceanic crust. These pressures are interpreted to reflect an underplating zone at 7-14 km depth where ascending magmas become ponded prior to eruption and where passing magmas temporarily stagnate during eruption. The underplating zone is inferred to extend to a radius of ca. 30 km at least, and its depth appears to increase slightly with distance to the rift axis. Our data thus show a remarkable pressure bimodality for long-term and short-term storage of magma that appears to be characteristic for Cumbre Vieja. By using a simple model based on the cumulative volume of material added to the crust, we have estimated uplift rates of > 0.5 m/ka due to underplating that occurs on the island scale. On a time-scale of some 10 ka, these uplift rates are of similar magnitude as global changes in sea-level. A second, more local mode of uplift and related faulting is caused by shallow intrusions into the volcanic edifice as is indicated by the highly irregular morphology of the Cumbre Vieja. We stress that intrusion-related uplift should be qualitatively considered when reconstructing the evolution of oceanic island volcanoes. Since most of the underplated material is inferred to consist of cumulate rocks being intimately mixed and juxtaposed with the lower oceanic crust and having similar densities, it is probably impossible to detect such an underplating zone seismically.

  20. Experimental constraints on steam-driven eruptions at White Island volcano (New Zealand)

    NASA Astrophysics Data System (ADS)

    Scheu, Bettina; Mayer, Klaus; Gilg, H. Albert; Heap, Michael J.; Kennedy, Ben M.; Lavallée, Yan; Letham-Brake, Mark; Jolly, Arthur; Dingwell, Donald B.

    2015-04-01

    The recent activity at White Island volcano is primarily characterized by strong hydrothermal activity interspersed by sequences of phreatic and phreatomagmatic eruptions, down to micro-eruptions through a mud-rich crater lake. We analyzed the response of various sample types to rapid decompression caused by steam-flashing and/or gas expansion, mimicking steam-driven (phreatic) eruptions. The samples investigated comprise unconsolidated ash/lapilli as well as consolidated ash tuffs with different degree of alteration. All sample sets underwent, where possible, microstructural, geochemical and petrophysical characterization (as porosity, permeability and uniaxial compressive strength (UCS)). This allowed us to assess the role of following factors for phreatic eruptions: (1) PT-conditions leading to either steam-flashing or steam expansion (2) the behavior of loose versus consolidated material, as the influence of fragmentation, ejection velocity, grain size reduction (3) the porosity and its changes, (4) the alteration of the samples, leading to changes in UCS, porosity, and permeability. Besides their role during the short moment of a phreatic eruption itself, the strength and the permeability of rocks of the entire White Island volcanic complex and in detail above the hydrothermal system in the crater area are key factors for the recent activity at White Island. They crucially influence the distribution of fluids and gases; strong and low-permeable layers can act as pressure seals, defining the area and overpressure of a steam-driven eruption.

  1. Mechanical behaviour and failure modes in the Whakaari (White Island volcano) hydrothermal system, New Zealand

    NASA Astrophysics Data System (ADS)

    Heap, Michael J.; Kennedy, Ben M.; Pernin, Noémie; Jacquemard, Laura; Baud, Patrick; Farquharson, Jamie I.; Scheu, Bettina; Lavallée, Yan; Gilg, H. Albert; Letham-Brake, Mark; Mayer, Klaus; Jolly, Arthur D.; Reuschlé, Thierry; Dingwell, Donald B.

    2015-03-01

    Volcanic hydrothermal systems host a prodigious variety of physico-chemical conditions. The physico-chemical state and mechanical behaviour of rocks within is correspondingly complex and often characterised by vast heterogeneity. Here, we present uniaxial and triaxial compression experiments designed to investigate the breadth of mechanical behaviour and failure modes (dilatant or compactant) for hydrothermally-altered lava and ash tuff deposits from Whakaari (White Island volcano) in New Zealand, a volcano with a well-documented and very active hydrothermal system. Our deformation experiments show that the failure mode of low porosity lava remains dilatant over a range of depths (up to pressures corresponding to depths of about 2 km). Upon failure, shear fractures, the result of the coalescence of dilatational microcracks, are universally present. The high porosity ash tuffs switch however from a dilatant to a compactant failure mode (driven by progressive distributed pore collapse) at relatively low pressure (corresponding to a depth of about 250 m). We capture the salient features of the dynamic conditions (e.g., differential stress, effective pressure) in a schematic cross section for the Whakaari hydrothermal system and map, for the different lithologies, areas susceptible to either dilatant vs. compactive modes of failure. The failure mode will impact, for example, the evolution of rock physical properties (e.g., porosity, permeability, and elastic wave velocity) and the nature of the seismicity accompanying periods of unrest. We outline accordingly the potential implications for the interpretation of seismic signals, outgassing, ground deformation, and the volcanic structural stability for Whakaari and similar hydrothermally-active volcanoes worldwide.

  2. Volcanic emissions from soils at the base of La Fossa volcano, Vulcano island, Italy

    NASA Astrophysics Data System (ADS)

    Obenholzner, J. H.; Parks, J. L.

    2006-12-01

    A top-sealed plastic tube with a diameter of ca. 15 cm had been buried vertically at the base of La Fossa volcano, Volcano island, Italy, next to the front of the obsidian flow. The tube had been filled with quartz wool to condense vapors emanating from the soil. At ca. 75 cm below the surface the sample had been exposed to vapors from Sept. 2005 to April 2006. The leached sample had not been in touch with the ground. Another glass wool cushion (ca. 3 cm thick) had been underneath to minimize capillary effects. Leaching of the quartz wool and ICP-MS analysis documented positive values for: Mg, Al, Si, P, K, Ca, Cr, Mn, Ni, Cu, Zn, Cd, Sn, Pb. Leaching with nitric acid documented also V and Fe. Acid leaching produced higher values for all elements, except K and Sn, than leaching with deionized water. Negative values had been obtained for As, Se, Mo. Influence from soil breathing can be excluded as the active fumaroles contain As and Se. This experiment documents for the first time an unknown element transport by vapors/gases through a volcanic edifice interacting with hydrothermal and magmatic gases. It remains unknown if elements detected are entering the atmosphere or are getting adsorbed onto the volcanic ash soil particles derived from reworked surge beds. This question is very important as soils might be an unknown filter medium to filter volcanically polluted air in case of major volcanic crises. Data can be obtained from the authors.

  3. Soil CO2 emissions at Furnas volcano, So Miguel Island, Azores archipelago: Volcano monitoring perspectives, geomorphologic studies, and land use planning application

    NASA Astrophysics Data System (ADS)

    Viveiros, FTima; Cardellini, Carlo; Ferreira, Teresa; Caliro, Stefano; Chiodini, Giovanni; Silva, Catarina

    2010-12-01

    Carbon dioxide (CO2) diffuse degassing structures (DDS) at Furnas volcano (So Miguel Island, Azores) are mostly associated with the main fumarolic fields, evidence that CO2 soil degassing is the surface expression of rising steam from the hydrothermal system. Locations with anomalous CO2 flux are mainly controlled by tectonic structures oriented WNW-ESE and NW-SE and by the geomorphology of the volcano, as evidenced by several DDS located in depressed areas associated with crater margins. Hydrothermal soil CO2 emissions in Furnas volcano are estimated to be 968 t d-1. Discrimination between biogenic and hydrothermal CO2 was determined using a statistical approach and the carbon isotope composition of the CO2 efflux. Different sampling densities were used to evaluate uncertainty in the estimation of the total CO2 flux and showed that a low density of points may not be adequate to quantify soil emanations from a relatively small DDS. Thermal energy release associated with diffuse degassing at Furnas caldera is about 118 MW (from an area of 4.8 km2) based on the H2O/CO2 ratio in fumarolic gas. The DDS also affect Furnas and Ribeira Quente villages, which are located inside the caldera and in the south flank of the volcano, respectively. At these sites, 58% and 98% of the houses are built over hydrothermal CO2 emanations, and the populations are at risk due to potential high concentrations of CO2 accumulating inside the dwellings.

  4. Chlorine-rich pyrometamorphic magma at White Island volcano, New Zealand

    NASA Astrophysics Data System (ADS)

    Wood, C. Peter; Browne, Patrick R. L.

    1996-07-01

    The 25 January 1987 phreatomagmatic eruption of Congress Vent on White Island volcano ejected paralava bombs derived from pockets of pyrometamorphic magma. The current White Island magmas are calc-alkaline basaltic andesite/andesite, but the paralavas are mostly highly peralkaline with molar(Na2O + K2O)/Al2O3 ratios from 1 to 22 recorded in matrix glasses. The glass compositions are highly variable, though quench crystals of tridymite, wollastonite and green clinopyroxene are ubiquitous, while albite occurs only in the least peralkaline samples. All have high alkali contents (Na2O + K2O > 10%) and chlorine mostly > 1% and up to 1.7%. The paralava glasses represent the most Cl-rich volcanic melts yet discovered. They display a strong positive correlation between Cl and total Fe, but a negative correlation between Cl and normative alkali feldspar content. It is likely that the Fe content of melts was the dominant control over Cl solubility, not their alumina-alkali systematics. Possible parent rocks for the pyrometamorphic magmas include halite-cemented crater-lake sediments and acid-sulfate hydrothermally altered vent breccias and tuffs, as found in the eruption deposits together with the paralava bombs. Fusion probably occurred at temperatures between 830 and 1000 °C and at a pressure below 5 MPa in a regime where silicate melts were buffered by immiscible NaCl-saturated aqueous vapor and hydrosaline melt. The conditions required to form the paralava bombs appear to be uncommon, but it is likely that similar pyrometamorphic melts could be generated at many volcanoes where shallow magma penetrates a hydrothermal system.

  5. CO2 budget from active volcanoes of central Mediterranean: preliminary estimate for Ischia Island (Italy).

    NASA Astrophysics Data System (ADS)

    Pecoraino, G.; Brusca, L.; D'Alessandro, W.; Giammanco, S.; Inguaggiato, S.; Longo, M.

    2003-12-01

    Ischia Island (46 km2) is an active volcano located a few kilometres northwest of the bay of Naples (Central Italy). It last erupted in 1302 A.D. and its activity is currently characterised only by low-temperature (T max. = 100 C) gas emissions, such as fumaroles and anomalous soil degassing. A geothermal reservoir (estimated reservoir temperature near 280 C; Inguaggiato et al., 2000) is also present in the island. The emitted gases are mostly water vapour and CO2. Also H2 is present in appreciable amounts (up to 2.5 % v/v of dry gas), together with minor concentrations of CH4 He and CO. Based on helium and carbon isotopic ratios (R/Ra 3.6; ? 13C(CO2) -2 \\permil), a magmatic source can be inferred for these gases. The present study was mainly aimed at carrying out a preliminary estimate of the total output of magmatic CO2 from Ischia, considering all types of fluids emitted there. Soil CO2 fluxes (measured with the accumulation chamber) gave a value of about 2.5 Mt a-1, that is much lower than the amount estimated at Mt. Etna (13 to 25 Mt a-1; Allard et al., 1991; D'Alessandro et al., 1997), but more than an order of magnitude higher than that estimated at Pantelleria Island and at Vulcano (Favara et al., 2001). The amount of CO2 dissolved into ground water as carbonatic species is only 0.025 Mt a-1, considering an annual volume of infiltrated water of about 8 x 106 m3. The overall output of CO2 from Ischia indicates that this island is site of active volcanic degassing and deserves a more careful volcanological monitoring.

  6. 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 (125110 and 138512 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 5228 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 59816 and 60215 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 1558 to 9818 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.

  7. 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.

  8. Three-armed rifts or masked radial pattern of eruptive fissures? The intriguing case of El Hierro volcano (Canary Islands)

    NASA Astrophysics Data System (ADS)

    Becerril, L.; Galindo, I.; Martí, J.; Gudmundsson, A.

    2015-04-01

    Using new surface structural data as well as subsurface structural data obtained from seventeen water galleries, we provide a comprehensive model of the volcano-tectonic evolution of El Hierro (Canary Islands). We have identified, measured and analysed more than 1700 volcano-structural elements including vents, eruptive fissures, dykes and faults. The new data provide important information on the main structural patterns of the island and on its stress and strain fields, all of which are crucial for reliable hazard assessments. We conducted temporal and spatial analyses of the main structural elements, focusing on their relative age and association with the three main cycles in the construction of the island: the Tiñor Edifice, the El Golfo-Las Playas Edifice, and the Rift Volcanism. A radial strike distribution, which can be related to constructive episodes, is observed in the on-land structures. A similar strike distribution is seen in the submarine eruptive fissures, which are radial with respect to the centre of the island. However, the volcano-structural elements identified onshore and reflecting the entire volcano-tectonic evolution of the island also show a predominant NE-SW strike, which coincides with the main regional trend of the Canary archipelago as a whole. Two other dominant directions of structural elements, N-S and WNW-ESE, are evident from the establishment of the El Golfo-Las Playas edifice, during the second constructive cycle. We suggest that the radial-striking structures reflect comparatively uniform stress fields during the constructive episodes, mainly conditioned by the combination of overburden pressure, gravitational spreading, and magma-induced stresses in each of the volcanic edifices. By contrast, in the shallower parts of the edifice the NE-SW, N-S and WNW-ESE-striking structures reflect local stress fields related to the formation of mega-landslides and masking the general and regional radial patterns.

  9. The 1998-1999 seismic series at Deception Island volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Ibez, J. M.; Carmona, E.; Almendros, J.; Saccorotti, G.; Del Pezzo, E.; Abril, M.; Ortiz, R.

    2003-11-01

    During the 1998-1999 Antarctic summer the pattern of seismic activity at Deception Island volcano changed significantly. The change was characterized by the occurrence of an intense swarm of volcano-tectonic (VT) earthquakes. More than 2000 VT earthquakes with S-P times smaller than 4 s were recorded in the period January-February 1999. Pure volcanic events were also detected; especially long-period (LP) events, volcanic tremor and some hybrid events. Seismic monitoring was performed using two short-period small-aperture arrays, among other instruments. Based on their signal-to-noise ratios we selected 863 VT earthquakes, 350 LP events and tremor episodes, and 9 hybrid events for analysis. We estimated apparent slowness and back-azimuth for all events using the Zero Lag Cross-Correlation array technique. Combining this information with S-P times and other indirect evidence, we identified two different source regions. LP seismicity is located less than 1-1.5 km southwest of the Fumarole array site. These events are likely to have a hydrothermal origin. VT earthquakes and hybrid events are located at depths of 0.3-10 km in an area under the bay of Deception Island. The area extends from the Fumarole array to the northeast with epicentral distances that range from 0.5 to 12 km. Most hypocenters are clustered in a small volume of around 8 km 3. The sources of the LP seismicity and the VT earthquakes are spatially distinct, which indicates that they are not produced by the same mechanisms. Moment magnitude analyses of the VT earthquakes provide an average magnitude of 0.5 and very low average stress drop, around 1 bar. A study of first motion of the P-waves suggests that the events in this small source region should have a variety of source mechanisms. This is supported by the existence of families of events with the same waveforms. The occurrence of repeating fracture processes with low stress drop and small fault dimensions can be explained by the lubrication of pre-existing zones of weakness by pressurized fluids. The most probable hypothesis that explains the generation of this seismic series at Deception Island is: a seismic series caused by the stress generated by the uplift of the source area due to a magmatic injection in depth. We favor this hypothesis since it is compatible with the majority of the characteristics of the seismicity and explains the spatial and temporal behavior of the series.

  10. 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 μ 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.

  11. Petrologic observations and multiphase dynamics in highly-crystalline magmatic mushes sourcing Galpagos Island volcanoes

    NASA Astrophysics Data System (ADS)

    Schleicher, J.; Bergantz, G. W.; Geist, D.

    2013-12-01

    The inability to directly observe magma chambers makes it difficult to understand their dynamics. Yet conditions within the chamber determines whether an eruption will occur, or if the magma is allowed to cool to complete crystallization. Eruption styles are also conditioned by these dynamics, as the amount of overpressure within the chamber regulates effusive or explosive eruptions. Plutons and volcanoes appear to share similar states: magma reservoirs that are temporally and spatially dominated by crystal-rich states, known as magmatic mushes. To explore the dynamics of mushes, we turn to the relatively simple ocean island end-member of magmatic systems. Ocean island porphyritic basalt flows provide a snapshot of the mush conditions prior to eruption. The Galpagos Islands are a system of ocean islands displaying spatial and temporal variation in their eruption styles and deposits. We have collected porphyritic basalt samples from Rbida Island of the Galpagos Archipelago which contains deposits ranging in ages from 0.7-1.0 Ma. Chemical zoning within phenocrysts indicates intermittent efficient mixing occurs within the mush, despite high viscosities and corresponding low-Reynolds number conditions. To further explore the dynamics of mixing, we present preliminary Eulerian-Lagrangian multiphase models using the fluids modeling software MFIX (Multiphase Flow with Interphase eXchanges). This computational fluid dynamics-discrete element method (CFD-DEM) allows for individual crystal tracking within the system and monitors interactions between the fluid and solid phases. Of special interest is the open-system dynamical response of a mush to a reintrusion event. Unlike high-Reynolds number flows, such as air or water systems, magmatic mushes have high viscosities, indicating that turbulent motion is not the primary mixing mechanism. Instead, mixing appears to be caused by mechanical unlocking from an increase in pore pressure as additional magma is injected. The crystal pile inflates and the injected melt creates crystal-poor fingers through the mush. These regions are unstable and eventually lead to mush collapse. Repetition of this cycle can drive efficient mixing of the magma chamber. We quantify the ability of the mush to mix using the Lacey statistical mixing index. We compare this value for the results of various open-system reintrusion events within the mush as a means to explore the dynamics that occur.

  12. 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.

  13. Spatial variation of seismic b-values beneath Makushin Volcano, Unalaska Island, Alaska

    NASA Astrophysics Data System (ADS)

    Bridges, David L.; Gao, Stephen S.

    2006-05-01

    The frequency-magnitude distribution was spatially mapped beneath Makushin Volcano, Unalaska Island, Alaska using an earthquake catalog of 491 events that occurred between July 2001 and April 2005. An area of high seismic b-values ( 2.0) is found 4 km east of Makushin's main vent at a depth between 4 and 7 km. The anomaly is statistically significant based on Utsu's p-test [T. Utsu, On seismicity, in Report of the Joint Research Institute for Statistical Mathematics, Tokyo (1992) 139-157], and is not data processing method or parameter dependent. Interestingly, a recent InSAR interferometric study [Z. Lu, J.A. Power, V.S. McConnell, C. Wicks Jr., D. Dzurism, Preeruptive inflation and surface interferometric coherence characteristics by satellite radar interferometry at Makushin volcano, Alaska: 1993-2000, J. Geophys. Res. 107 (2002) 2266, doi:10.1029/2001JB000970] inferred a surface uplift of about 7 cm during the two-year period prior to October 1995, centered approximately in the area with the observed anomalous b-values. The uplift was caused by the volume increase of an inferred magma chamber at a depth of about 7 km. The close correspondence of the seismic and InSAR observations suggests that the heterogeneous area associated with the observed high b-values is most likely the result of increased crack density associated with the magma chamber. This study demonstrates the effectiveness of combining InSAR and seismological observations in locating magma chambers and areas of high heterogeneity in the crust.

  14. 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

  15. 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. )

    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.

  16. 3-D Anisotropic Ambient Noise Tomography of Piton De La Fournaise Volcano (La Runion Island)

    NASA Astrophysics Data System (ADS)

    Mordret, A.; Rivet, D. N.; Landes, M.; Shapiro, N.

    2014-12-01

    We cross-correlate four years of seismic noise continuously recorded by the seismic monitoring network of the Piton de la Fournaise volcano (La Runion Island). The network is composed of 40 stations 27 of which have 3-component sensors. We use Vertical-to-Vertical (ZZ) cross-correlation components from all stations and Radial-to-Radial (RR) and Transverse-to-Transverse (TT) cross-correlations computed from 3-component records. The group velocity dispersion curves for Rayleigh and Love waves are measured using a Frequency-Time Analysis. We average measurements from ZZ and RR components to finally obtain 577 Rayleigh-wave dispersion curves. 395 Love-wave dispersion curves are obtained from the TT cross-correlations. We then regionalize the group velocities measurements to construct 2D dispersion maps at a set of periods between 0.4 and 8 s. Finally, we construct a 3D shear-velocity model down to 3 km below the sea level by jointly inverting the Rayleigh and Love wave group velocity maps with a Neighborhood Algorithm and with taking into account the radial anisotropy. The distribution of 3-D Voigt averaged S-wave velocities shows three distinct high-velocity anomalies surrounded by a low-velocity ring. The most western high-velocity anomaly is located below the actual "Plaine des Sables" and could be attributed 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 is located below the summit of the volcano and likely corresponds to the actual preferential dyke intrusion zone as highlighted by the seismicity. The third high-velocity anomaly is located below the "Grandes Pentes" and the "Grand Brl" areas and is thought to be an imprint of the solidified magma chamber of the ancient dismantled "Les Aliz" volcano. The distribution of the radial anisotropy shows two main anomalies: a positive anisotropy (Vsh>Vsv) above sea level highlighting the recent edifice of Piton de la Fournaise with an accumulation of mostly horizontal lava flows, and the second one below the sea level with a negative anisotropy (Vsv>Vsh) showing the ancient edifice of the Piton de la Fournaise dominated by intrusions of vertical dykes.

  17. Movement of shallow magmatic sources inferred from volcano-tectonic faults: An example from Shinjima Island nearby Sakurajima volcano, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Yoshinaga, Y.; Haraguchi, T.; Toda, S.; Miki, D.; Imura, R.

    2006-12-01

    Uplift and subsidence due to magma movement involve complex fault system at the surface of a volcano. Conversely, mapping volcano-tectonic faults and surface deformation allows us to infer the feeding system of magma and eruption process in the past. Here we represent a case study of such deformation and a complex fault system associated with prehistoric and historic volcanic uplifts on and around Shinjima Island that is a small island of ~0.2 square meter located northeast of Sakurajima volcano, Kagoshima Bay, southwest Japan. Combining detail mapping of the faults and dislocation modeling, we reveal geometry, volume, and depth of the magma intrusion during the past eruptions that produced the current Shinjima landform. According to historical records, Shinjima Island was uplifted and emerged from bottom of the sea at the eruption of Sakurajima in 1779. Shinjima Island that is characterized by horst-and-graben structures caused by numerous E-W striking normal faults. The island is mainly composed of pyroclastic deposits, top of which exposes Moejima shell bed that consists of shell fossils yielded a radiocarbon age of 6,000 - 2,300 yr BP. Assuming the shells had been borne horizontally below the water level before the eruption, we applied the shell bed to a piercing point to estimate the fault vertical separation. We measured the height of the shell bed at 75 points along the coastline and then found the faults on both sides of the main graben vertically offset 15.9m, and 23.5m respectively. In addition to the surface mapping, we made E-W and N-S seismic reflection profiles across Shinjima Island. The N-S profile shows a structure that swells up the geologic units (pyroclastic deposits and andestic lava recovered from a deep borehole by Kyoto University) broadly between 200m and 350m in contrast to the narrow surface deformation. The profile suggests the fault displacements do not extend deeper than ~100m below the surface. We also made the 3D submarine topography using bathymetric charts around An'ei Islands which were newly formed during the 1779 eruption. The topography shows An'ei Islands including Shinjima are on the An'ei Plateau which size is about 3 by 5 km. To estimate the magma storage and movement at the 1779 eruption and the predecessors, we performed forward modeling to restore the surface deformation in elastic half-space. A complex model combining a point source inflation and dike intrusions approximately reproduces the current Shinjima landform. The model suggests that the island was uplifted by two-stage volcanic growth. The former is a wide-area bulging formed An'ei Plateau by a deep magma expansion. The latter is the solo uplift of Shinjima Island accompanied with a ridge-trough-ridge structure by a shallow dike intrusion.

  18. Solomon's Sea and [Pi

    ERIC Educational Resources Information Center

    Simoson, Andrew J.

    2009-01-01

    This paper is a whimsical survey of the various explanations which might account for the biblical passage in I Kings 7:23 that describes a round object--a bronze basin called Solomon's Sea--as having diameter ten cubits and circumference thirty cubits. Can the biblical pi be any number other than 3? We offer seven different perspectives on this

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

    NASA Astrophysics Data System (ADS)

    Turner, S. P.

    2002-12-01

    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 102-104 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 226Ra 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.

  20. 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

  1. 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)

    Hernndez, Iigo; Hernndez, Pedro; Prez, Nemesio; Tanaka, Hiroyuki; Miyamoto, Seygo; Barrancos, Jos; Padrn, 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.

  2. The forensics of sub-surface processes on island volcanoes from integrated geodetic observations: results from Tenerife and Montserrat (Invited)

    NASA Astrophysics Data System (ADS)

    Gottsmann, J.

    2009-12-01

    Spatio-temporal variations in geodetic signals at active volcanoes provide important insight on governing subsurface processes. This contribution explores the phenomenology of volcanic unrest and eruptive activity from the perspective of both ground deformation and gravimetric investigations at an ocean island volcanic complex (Tenerife, Canary Islands) and an active andesitic arc volcano (Soufrière Hills volcano [SHV], Montserrat). Despite their marked differences in volcanic evolution and tectonic settings both volcanic systems show remarkable similarities in their subsurface processes. On Tenerife, during unrest in 2004-5, mass movement at depth was quantified by time-lapse gravimetric observations despite the absence of significant ground deformation. Shallow migration of hydrous fluids is identified as the main cause for the unrest marking the reactivation of the central volcanic complex after a century of quiescence. The combination of static and dynamic gravimetric data reveals a causality between the major structural building blocks of the island and the pattern of mass variations. Low density bodies underlie areas of maximum mass variations at the complex. Gravimetric data also indicate that the shallow plumbing system of the 3700 m tall Pico Teide/Pico Viejo composite volcano remained unaffected by the unrest. On Montserrat, time-lapse gravimetric data invoke the existence of a previously unrecognized fault zone beneath the centre of the island that is influenced by changes in stress distribution associated with volcanic activity at SHV. The fault zone either provides a trace for ground water flow or responds to a changed stress field via volcano-tectonic coupling with an elastic opening/closing of fractures. Continuous gravimetric (CG) data enabled the calibration of a new precision tidal model for the island resulting in a reduction of the signal-to-noise ratio by about one order of magnitude. Detided CG records reveal particular gravity perturbations a few minutes before the onset of Vulcanian eruptions in 2008. The gravity anomalies are inconsistent with mass variations in either a shallow magma reservoir or the active dyke-conduit system. Some waveforms may reflect very low-frequency seismicity (<0.05 Hz) associated with ensuing eruptions dominated by rock ballistics.

  3. Experimental constraints on phreatic eruption processes at Whakaari (White Island volcano)

    NASA Astrophysics Data System (ADS)

    Mayer, Klaus; Scheu, Bettina; Gilg, H. Albert; Heap, Michael J.; Kennedy, Ben M.; Lavallée, Yan; Letham-Brake, Mark; Dingwell, Donald B.

    2015-09-01

    Vigorous hydrothermal activity interspersed by sequences of phreatic and phreatomagmatic eruptions occur at Whakaari (White Island volcano), New Zealand. Here, we investigate the influence of sample type (hydrothermally altered cemented ash tuffs and unconsolidated ash/lapilli) and fragmentation mechanism (steam flashing versus gas expansion) on fragmentation and ejection velocities as well as on particle-size and shape. Our rapid decompression experiments show that fragmentation and ejection speeds of two ash tuffs, cemented by alunite and amorphous opal, increase with increasing porosity and that both are significantly enhanced in the presence of steam flashing. Ejection speeds of unconsolidated samples are higher than ejection speeds of cemented tuffs, as less energy is consumed by fragmentation. Fragmentation dominated by steam flashing results in increased fragmentation energy and a higher proportion of fine particles. Particle shape analyses before and after fragmentation reveal that both steam flashing and pure gas expansion produce platy or bladed particles from fracturing parallel to the decompression front. Neither fragmentation mechanisms nor sample type show a significant influence on the shape. Our results emphasize that, under identical pressure and temperature conditions, eruptions accompanied by the process of liquid water flashing to steam are significantly more violent than those driven simply by gas expansion. Therefore, phase changes during decompression and cementation are both important considerations for hazard assessment and modeling of eruptions in hydrothermally active environments.

  4. 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.

  5. 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 μS/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 μS/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 μS/cm, at 520 m an average of 129 μS/cm, at 430 m an average of 182 μS/cm, at 200 m an average of 192 μS/cm and at 12 m high sea level and average of 472 μS/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 δ18O and δD 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.

  6. Sar interferometry time series analysis of surface deformation for Piton de la Fournaise volcano, Reunion Island

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Remy, Dominique; Froger, Jean-Luc; Darrozes, José; Bonvalot, Sylvain

    2015-04-01

    Piton de la Fournaise, located on the south-eastern side of Réunion Island in the Indian Ocean, is a hotspot oceanic basaltic shield volcano whose activity began more than 500,000 years ago. It is one of the most active volcanoes in the world with a high eruptive frequency on average one eruption every 9 months since 1998. In April 2007, Piton de la Fournaise experienced an exceptional eruption which is considered as the largest historical eruption ever observed during the 20th and 21th centuries, characterized by an effusion of 210 ×106 m3 volume of lava with a 340 m consequent collapse of the Dolomieu crater and the onset of a landslide on the eastern flank. ENVISAT and ALOS data analysis showed that the subsidence of central cone and landslide of eastern flank continued deforming after this eruption at least until June 2008, but no clear ground deformation has been detected after this date from Band-C or Band-L radar images. We so perform a detailed spatio-temporal analysis of ground motions on Piton de la Fournaise using X-band InSAR time series acquired from 2009 to 2014. X-Band was chosen because it provides high spatial resolution (up to 1 m), short revisit period (minimum 11 days) and a highest sensibility to ground deformation. Our large dataset of X-band radar images is composed of 106 COSMO-SkyMed and 96 TerraSAR-X Single-Look Complex images acquired in ascending and descending orbits. The interferograms were generated using DORIS. A high resolution reference Digital Elevation Model (DEM) (5m x 5m Lidar DEM) was used to model and remove the topographic contribution from the interferograms. We employed next StaMPS/MTI (Hooper et al., 2012) to generate the displacement time series and we analyzed the time-dependant behavior of surface displacement using a principal component analysis (PCA) decomposition. This analysis clearly reveals that the large eastward motion affecting the eastern flank of Piton de la Fournaise remained active (LOS velocity of about 25 mm.y-1) at least until July 2012. Another important result is that the displacement maps show evidence of time-dependant processes acting at the central cone.

  7. Zn isotope compositions of the thermal spring waters of La Soufrire volcano, Guadeloupe Island

    NASA Astrophysics Data System (ADS)

    Chen, Jiu-Bin; Gaillardet, Jrme; Dessert, Cline; 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 Soufrire, 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 Soufrire 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.

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

    USGS Publications Warehouse

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

    2003-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The Island of Hawai';i is home to the most active volcanoes in the Hawaiian Islands. The island's isolated nature, combined with the lack of permanent offshore seismometers, creates difficulties in recording small magnitude earthquakes with accuracy. This background offshore seismicity is crucial in understanding the structure of the lithosphere around the island chain, the stresses on the lithosphere generated by the weight of the islands, and how the volcanoes interact with each other offshore. This study uses the data collected from a 9-month deployment of a temporary ocean bottom seismometer (OBS) network fully surrounding Lo';ihi volcano. This allowed us to widen the aperture of earthquake detection around the Big Island, lower the magnitude detection threshold, and better constrain the hypocentral depths of offshore seismicity that occurs between the OBS network and the Hawaii Volcano Observatory's land based network. Although this study occurred during a time of volcanic quiescence for Lo';ihi, it establishes a basis for background seismicity of the volcano. More than 480 earthquakes were located using the OBS network, incorporating data from the HVO network where possible. Here we present relocated hypocenters using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), as well as tomographic images for a 30 km square area around the summit of Lo';ihi. Illuminated by using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), offshore seismicity during this study is punctuated by events locating in the mantle fault zone 30-50km deep. These events reflect rupture on preexisting faults in the lower lithosphere caused by stresses induced by volcano loading and flexure of the Pacific Plate (Wolfe et al., 2004; Pritchard et al., 2007). Tomography was performed using the double-difference seismic tomography method TomoDD (Zhang & Thurber, 2003) and showed overall velocities to be slower than the regional velocity model (HG50; Klein, 1989) in the shallow lithosphere above 16 km depth. This is likely a result of thick deposits of volcaniclastic sediments and fractured pillow basalts that blanket the southern submarine flank of Mauna Loa, upon which Lo';ihi is currently superimposing (Morgan et al., 2003). A broad, low-velocity anomaly was observed from 20-40 km deep beneath the area of Pahala, and is indicative of the central plume conduit that supplies magma to the active volcanoes. A localized high-velocity body is observed 4-6 km deep beneath Lo';ihi's summit, extending 10 km to the North and South. Oriented approximately parallel to Lo';ihi's active rift zones, this high-velocity body is suggestive of intrusion in the upper crust, similar to Kilauea's high-velocity rift zones.

  10. Reed-Solomon decoder

    NASA Technical Reports Server (NTRS)

    Lahmeyer, Charles R. (Inventor)

    1987-01-01

    A Reed-Solomon decoder with dedicated hardware for five sequential algorithms was designed with overall pipelining by memory swapping between input, processing and output memories, and internal pipelining through the five algorithms. The code definition used in decoding is specified by a keyword received with each block of data so that a number of different code formats may be decoded by the same hardware.

  11. Seismic monitoring at Deception Island volcano (Antarctica): the 2010-2011 survey

    NASA Astrophysics Data System (ADS)

    Martín, R.; Carmona, E.; Almendros, J.; Serrano, I.; Villaseñor, A.; Galeano, J.

    2012-04-01

    As an example of the recent advances introduced in seismic monitoring of Deception Island volcano (Antarctica) during recent years, we describe the instrumental network deployed during the 2010-2011 survey by the Instituto Andaluz de Geofísica of University of Granada, Spain (IAG-UGR). The period of operation extended from December 19, 2010 to March 5, 2011. We deployed a wireless seismic network composed by four three-component seismic stations. These stations are based on 24-bit SL04 SARA dataloggers sampling at 100 sps. They use a PC with embedded linux and SEISLOG data acquisition software. We use two types of three-component seismometers: short-period Mark L4C with natural frequency of 1 Hz and medium-period Lennartz3D/5s with natural frequency of 0.2 Hz. The network was designed for an optimum spatial coverage of the northern half of Deception, where a magma chamber has been reported. Station locations include the vicinity of the Spanish base "Gabriel de Castilla" (GdC), Obsidianas Beach, a zone near the craters from the 1970 eruptions, and the Chilean Shelter located south of Pendulum Cove. Continuous data from the local seismic network are received in real-time in the base by wifi transmission. We used Ubiquiti Networks Nanostation2 antennas with 2.4 GHz, dual-polarity, 10 dBi gain, and 54 Mbps transmission rate. They have shown a great robustness and speed for real-time applications. To prioritize data acquisition when the battery level is low, we have designed a circuit that allows independent power management for the seismic station and wireless transmission system. The reception antenna located at GdC is connected to a computer running SEISCOMP. This software supports several transmission protocols and manages the visualization and recording of seismic data, including the generation of summary plots to show the seismic activity. These twelve data channels are stored in miniseed format and displayed in real time, which allows for a rapid evaluation of the seismic activity and an efficient seismo-volcanic surveillance. The data are processed and analyzed using the SEISAN database management software. In addition to the seismic network, we deployed a small-aperture seismic array south of Fumarole Bay. It is composed by 9 vertical and 1 three-component short-period stations. The 24-bit data acquisition system samples these 12 channels at 100 sps. There is also a permanent seismic station operating since 2008 and located near GdC, that is very useful for the preliminary evaluation of the seismicity at the start of the survey. This station is composed by a 16-s electrolytic seismometer (Eentec SP400) and a 24-bit datalogger (Eentec DR4000) sampling at 100 sps. During the 2010-2011 survey we identified 33 regional earthquakes, 80 volcano-tectonic (VT) earthquakes, and 929 long-period (LP) events. The volcanic alert system has remained green (the lowest level) at all times. The seismic activity has been similar to previous surveys and remained within limits that are normal for the island.

  12. Seismovolcanic signals at Deception Island volcano, Antarctica: Wave field analysis and source modeling

    NASA Astrophysics Data System (ADS)

    IbEz, Jess M.; Pezzo, Edoardo Del; Almendros, Javier; La Rocca, Mario; Alguacil, Gerardo; Ortiz, Ramn; GarcA, Alicia

    2000-06-01

    The seismovolcanic signals associated with the volcanic activity of Deception Island (Antarctica), recorded during three Antarctic summers (1994-1995, 1995-1996 and 1996-1997), are analyzed using a dense small-aperture (500 m) seismic array. The visual and spectral classification of the seismic events shows the existence of long-period and hybrid isolated seismic events, and of low-frequency, quasi-monochromatic and spasmodic continuous tremors. All spectra have the highest amplitudes in the frequency band between 1 and 4 Hz, while hybrids and spasmodic tremors have also significant amplitudes in the high-frequency band (4-10 Hz). The array analysis indicates that almost all the well-correlated low-frequency signals share similar array parameters (slowness and back azimuth) and have the same source area, close to the array site. The polarization analysis shows that phases at high-frequency are mostly composed of P waves, and those phases dominated by low frequencies can be interpreted as surface waves. No clear shear waves are evidenced. From the energy evaluation, we have found that the reduced displacement values for surface and body waves are confined in a narrow interval. Volcano-tectonic seismicity is located close to the array, at a depth shallower than 1 km. The wave-field properties of the seismovolcanic signals allow us to assume a unique source model, a shallow resonating fluid-filled crack system at a depth of some hundreds of meters. All of the seismic activity is interpreted as the response of a reasonably stable stationary geothermal process. The differences observed in the back azimuth between low and high frequencies are a near-field effect. A few episodes of the degassification process in an open conduit were observed and modeled with a simple organ pipe.

  13. SAR-based Estimation of Glacial Extent and Velocity Fields on Isanotski Volcano, Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Sousa, D.; Lee, A.; Parker, O. P.; Pressler, Y.; Guo, S.; Osmanoglu, B.; Schmidt, C.

    2012-12-01

    Global studies show that Earth's glaciers are losing mass at increasing rates, creating a challenge for communities that rely on them as natural resources. Field observation of glacial environments is limited by cost and inaccessibility. Optical remote sensing is often precluded by cloud cover and seasonal darkness. Synthetic aperture radar (SAR) overcomes these obstacles by using microwave-frequency electromagnetic radiation to provide high resolution information on large spatial scales and in remote, atmospherically obscured environments. SAR is capable of penetrating clouds, operating in darkness, and discriminating between targets with ambiguous spectral signatures. This study evaluated the efficacy of two SAR Earth observation methods on small (< 7 km2) glaciers in rugged topography. The glaciers chosen for this study lie on Isanotski Volcano in Unimak Island, Aleutian Archipelago, USA. The local community on the island, the City of False Pass, relies on glacial melt for drinking water and hydropower. Two methods were used: (1) velocity field estimation based on Repeat Image Feature Tracking (RIFT) and (2) glacial boundary delineation based on interferometric coherence mapping. NASA Uninhabited Aerial Vehicle SAR (UAVSAR) single-polarized power images and JAXA Advanced Land Observing Satellite Phased Array type L-band SAR (ALOS PALSAR) single-look complex images were analyzed over the period 2008-2011. UAVSAR image pairs were coregistered to sub-pixel accuracy and processed with the Coregistration of Optically Sensed Images and Correlation (COSI-Corr) feature tracking module to derive glacial velocity field estimates. Maximum glacier velocities ranged from 28.9 meters/year to 58.3 meters/year. Glacial boundaries were determined from interferometric coherence of ALOS PALSAR data and subsequently refined with masking operations based on terrain slope and segment size. Accuracy was assessed against hand-digitized outlines from high resolution UAVSAR power images, yielding 83.0% producer's accuracy (errors of omission) and 86.1% user's accuracy (errors of commission). These results represent a refinement of a decades-old entry from the USGS National Hydrography Dataset (NHD). The information gained from this study could strengthen management practices by helping decision makers understand the ecological and economic consequences of glacial change. This procedure could be repeated in similar locations worldwide to provide communities with accurate, quantitative information about their changing glacial resources.

  14. Fluxes of magmatic chlorine and sulfur from volcano-hydrothermal systems. Examples for Northern Kuril Islands Paramushir and Shiashkotan.

    NASA Astrophysics Data System (ADS)

    Kalacheva, Elena; Taran, Yuri

    2015-04-01

    The total flux of components degassed from the magma through persistently degassing volcanoes comprises of the volcanic vapor flux from fumaroles to the atmosphere, diffuse flux through volcanic slopes and the hydrothermal flux to the local hydrologic network. The hydrothermal flux may be provided by the discharge of fluids formed at depth over the magma body and/or by acid waters which are formed by the absorption of the ascending volcanic vapor by shallow ground. The anion composition (Cl and SO4) of the discharging thermal waters from a volcano-hydrothermal system originates from the volcanic vapor and should be taken into account in estimations of the magmatic volatile output and volatile recycling in subduction zones. Here we report the chemical (major and trace elements) and isotopic composition of acidic and neutral thermal waters, chemical and isotopic composition of volcanic vapors and solute fluxes from the northern Kurilian islands Paramushir (Ebeko volcanic center) and Shiashkotan (volcanoes Sinarka and Kuntomintar). The total measured outputs of chloride and sulfur from the system in 2006-2014 were estimated on average as 730 g/s and 980 g/s, respectively, which corresponds to the equivalent fluxes of 64 t/d of HCl and 169 t/d of SO2. These values are one order of magnitude higher than the fumarolic output of Cl and S from the low-temperature fumarolic field of Ebeko (<120°C). The estimated discharge rate of hot (85°C) water from the system with ~ 3500 ppm of chloride is about 0.3 m3s-1 which is among the highest hot water natural outputs ever measured for a volcano-hydrothermal system. The total hydrothermal discharge of Cl and S from Shiashkotan island to the Sea of Okhotsk associated with magmatic activity of two volcanoes is estimated as ca. 20 t/d and 40 t/d, respectively, which is close to the fumarolic output from both volcanoes (Sinarka and Kuntomintar) estimated using the chemistry and flow rates of fumaroles those measured temperature is close to 500°C.

  15. 40Ar/39Ar geochronology of subaerial lava flows of Barren Island volcano and the deep crust beneath the Andaman Island Arc, Burma Microplate

    NASA Astrophysics Data System (ADS)

    Ray, Jyotiranjan S.; Pande, Kanchan; Bhutani, Rajneesh

    2015-06-01

    Little was known about the nature and origin of the deep crust beneath the Andaman Island Arc in spite of the fact that it formed part of the highly active Indonesian volcanic arc system, one of the important continental crust forming regions in Southeast Asia. This arc, formed as a result of subduction of the Indian Plate beneath the Burma Microplate (a sliver of the Eurasian Plate), contains only one active subaerial magmatic center, Barren Island volcano, whose evolutional timeline had remained uncertain. In this work, we present results of the first successful attempt to date crustal xenoliths and their host lava flows from the island, by incremental heating 40Ar/39Ar method, in an attempt to understand the evolutionary histories of the volcano and its basement. Based on concordant plateau and isochron ages, we establish that the oldest subaerial lava flows of the volcano are 1.58 0.04 (2?) Ma, and some of the plagioclase xenocrysts have been derived from crustal rocks of 106 3 (2?) Ma. Mineralogy (anorthite + Cr-rich diopside + minor olivine) and isotopic compositions (87Sr/86Sr < 0.7040; ?Nd > 7.0) of xenoliths not only indicate their derivation from a lower (oceanic) crustal olivine gabbro but also suggest a genetic relationship between the arc crust and the ophiolitic basement of the Andaman accretionary prism. We speculate that the basements of the forearc and volcanic arc of the Andaman subduction zone belong to a single continuous unit that was once attached to the western margin of the Eurasian Plate.

  16. Enhancement of sub-daily positioning solutions for surface deformation monitoring at Deception volcano (South Shetland Islands, Antarctica)

    NASA Astrophysics Data System (ADS)

    Prates, G.; Berrocoso, M.; Fernndez-Ros, A.; Garca, A.

    2013-02-01

    Deception Island is one of the most visited places in Antarctica. There are biological, geological, and archeological features that are major attractions within Port Foster, its horse shoe-shaped natural inner bay, and two scientific bases that are occupied during austral summers. Deception Island is an active volcano, however, and needs to be monitored in order to reduce risk to people on the island. Surface deformation in response to fluid pressure is one of the main volcanic activities to observe. Automated data acquisition and processing using the global navigation satellite systems allow measurements of surface deformation in near real time. Nevertheless, the positioning repeatability in sub-daily solutions is affected by geophysical influences such as ocean tidal loading, among others. Such periodic influences must be accurately modeled to achieve similar repeatability as daily solutions that average them. However, a single solution each 24 h will average out the deformation suffered during that period, and the position update waiting time can be a limitation for near real-time purposes. Throughout the last five austral summer campaigns in Deception, using simultaneous wireless communications between benchmarks, a processing strategy was developed to achieve millimeter-level half-hourly positioning solutions that have similar repeatability as those given by 24-h solutions. For these half-hourly solutions, a tidal analysis was performed to assess any mismodeling of ocean tide loading, and a discrete Kalman filter was designed and implemented to enhance the sub-daily positioning repeatability. With these solutions, the volcano-dynamic activity resulting in localized surface deformation for the last five austral summer campaigns is addressed. Although based on only three carefully located benchmarks, it is shown that Deception has been shortening and subsiding during these last 4 years. The method's accuracy in baselines up to a few hundred kilometers assures its applicability to other volcanoes worldwide.

  17. 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

  18. The 1998-1999 Seismic Series At Deception Island Volcano, Antarctica.

    NASA Astrophysics Data System (ADS)

    Ibez, J. M.; Carmona, E.; Almendros, J.; Saccorotti, G.; del Pezzo, E.; Abril, M.; Ortiz, R.; Martnez-Arvalo, C.

    During the 1998-1999 Antarctic summer, the pattern of seismic activity at Deception Island volcano suffered a significant change with respect to the previous years. This change was characterized by the occurrence of an intense swarm of local earthquakes. More than 2000 local earthquakes with S-P time smaller than 4 s were recorded in the period January-February 1999. Pure volcanic events have been also detected, spe- cially long period (LP) events and volcanic tremor, and some hybrid events. Seismic monitoring was performed using two short-period small-aperture arrays, among other instruments. We selected for the analysis 863 local earthquakes, 350 LP events and tremor episodes, and 9 hybrid events, based on their signal-to-noise ratios. Propaga- tion parameters (apparent slowness and back-azimuth) for all events were estimated using the zero lag cross-correlation (ZLCC) array technique. Combining this infor- mation with measures of S-P times and other indirect evidences, two different source regions have been identified. LP seismicity is located southwestward from the Fuma- role array site at distances smaller than 1-1.5 km. In this region we find the presence of glaciers, important fractures, and thermal anomalies, which supports the hypothesis of a hydrothermal origin. Local earthquakes and hybrid events are located in a region beneath Port Foster, the inner Bay of Deception Island. This region extends from the array site to the Northeast, between depths of 0.3 and 10 km. The epicentral distances range between 0.5 and 12 km. Most hypocenters are clustered in a small volume of around 8 km3 centered at 1.5 km depth and 1.5 km Northeast of the Fumarole ar- ray. The sources of the LP seismicity and the local earthquakes are spatially distinct, which indicates that they are not produced by the same mechanisms. Moment mag- nitude analyses of the local earthquakes show an energetic uniformity in the seismic series, with average magnitude of 0.5 and very low average stress drop, around 1 bar. The study of the spatial distribution of the first motion of the P-waves suggests that dif- ferent source mechanisms acted in a very small volume. The complexity of the source region is also evidenced by the identification of distinct families of events with the same waveforms inside the main source region. The occurrence of repeatable fracture processes with low stress drop and small fault dimensions can be explained by the lu- brication of pre-existing zones of weakness by pressurized fluids. Three mechanisms could be invoked to explain the generation of the recorded seismic series at Decep- 1 tion Island: 1) a classical tectonic seismic swarm caused by a regional stress field; 2) a seismic swarm produced directly by the actual movement of magma through the source region; and 3) a seismic series caused by the stress generated by the uplift of the source area due to a magmatic injection in depth. We favor the last hypothesis since it is compatible with the majority of the characteristics of the seismicicty and explains the spatial and temporal behavior of the series. 2

  19. 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.; Gonzlez-Dvila, 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.

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

    PubMed

    Fraile-Nuez, E; Gonzlez-Dvila, M; Santana-Casiano, J M; Arstegui, J; Alonso-Gonzlez, I J; Hernndez-Len, S; Blanco, M J; Rodrguez-Santana, A; Hernndez-Guerra, A; Gelado-Caballero, M D; Eugenio, F; Marcello, J; de Armas, D; Domnguez-Yanes, J F; Montero, M F; Laetsch, D R; Vlez-Belch, P; Ramos, A; Ariza, A V; Comas-Rodrguez, I; Bentez-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

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

    PubMed Central

    Fraile-Nuez, E.; Gonzlez-Dvila, M.; Santana-Casiano, J. M.; Arstegui, J.; Alonso-Gonzlez, I. J.; Hernndez-Len, S.; Blanco, M. J.; Rodrguez-Santana, A.; Hernndez-Guerra, A.; Gelado-Caballero, M. D.; Eugenio, F.; Marcello, J.; de Armas, D.; Domnguez-Yanes, J. F.; Montero, M. F.; Laetsch, D. R.; Vlez-Belch, P.; Ramos, A.; Ariza, A. V.; Comas-Rodrguez, I.; Bentez-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

  2. 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.

  3. Debris avalanche triggered by sill intrusions in basaltic volcanoes (Piton des Neiges, La Réunion Island)

    NASA Astrophysics Data System (ADS)

    Berthod, C.; Famin, V.; Bascou, J.; Michon, L.; Ildefonse, B.

    2014-12-01

    Debris avalanches derived from the flanks of volcanic islands are among the largest on Earth. Debris avalanches are rare, catastrophic destabilizations that still keep geologists debating about the mechanisms that initiate them and make them travel huge runout distances. To shed light on the trigger of such destabilizations, we studied the inland scar of a debris avalanche deposit cropping out at Piton des Neiges, a dormant and eroded basaltic volcano of La Réunion Island. The avalanche deposit rests on a pile of 50-70 sill intrusions with a shallow northward dip, i.e. toward the sea. We measured the anisotropy of magnetic susceptibility in a transect across the uppermost sill of the pile in contact with the avalanche deposit. This transect reveals a strongly asymmetric magnetic fabric, consistent with a north-directed shear movement of the upper intrusion wall. This suggests that the upper sill induced a co-intrusive shear displacement of the volcano flank toward the sea. The upper sill margin in contact with the avalanche is striated, showing that this intrusion is older than the avalanche. Striae indicate a northward direction of avalanche runout. The upper sill margin also displays a magmatic lineation consistent with a magma flow in the intrusion toward the north. There is thus a striking kinematic consistency between the directions of intrusion propagation and avalanche runout, both oriented toward the sea. From the above results, we propose that repeated sill intrusions, such as observed on Piton des Neiges, increase the instability of a volcanic edifice. Each injection induces an incremental slip of the overlying rock mass, which may eventually end up into a landslide. Sill intrusions associated with seaward displacements of volcano flank, such as inferred for the April 2007 eruption of Piton de la Fournaise (also in La Réunion), should therefore be considered as a potential trigger of debris avalanches.

  4. InSAR observations of the 1995 Fogo, Cape Verde, eruption: Implications for the effects of collapse events upon island volcanoes

    NASA Astrophysics Data System (ADS)

    Amelung, Falk; Day, Simon

    2002-06-01

    Fogo volcano, Cape Verde Islands, erupted in April 1995 after 43 years of dormancy. About 46 106 m3 of lava erupted during 7.5 weeks from vents on the SW flank of Pico do Fogo into Cha das Caldeiras. Interferograms obtained from 1993-1998 ERS SAR data show ground deformation due to the feeder dike but lack evidence for any volcano-wide deformation related to volume changes of a shallow magma reservoir. This suggests that Fogo is fed from a relatively deep, mantle-lithospheric source (>16.5 km depth), consistent with petrological data. This supports the concept that Cha das Caldeiras is the fill of a collapse scar created by a giant landslide, and not a collapse caldera overlying a central, shallow magma chamber. The disturbance of the magmatic system by giant landslides may explain why some oceanic island volcanoes with high magma supply rates currently lack well-developed shallow reservoirs.

  5. 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.

  6. 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.

  7. A new SO2 emissions budget for Anatahan volcano (Mariana Islands) based on ten years of satellite observations

    NASA Astrophysics Data System (ADS)

    McCormick, Brendan; Popp, Christoph; Andrews, Benjamin; Cottrell, Elizabeth

    2015-04-01

    Satellite remote sensing offers great potential for the study of sulphur dioxide (SO2) gas emissions from volcanoes worldwide. Anatahan is a remote volcano in the Mariana Islands, SW Pacific. Existing SO2 emissions data from Anatahan, from ground-based UV spectrometer measurements, place the volcano among the largest natural SO2 sources worldwide. However, these measurements are limited in number and only available from intervals of eruptive activity. Activity varies widely at Anatahan: over the past decade, records held in the Smithsonian Institution Global Volcanism Program Volcanoes of the World database describe the alternation of intense eruptions with long intervals of quiescence, where much lower intensity activity took place. We present ten years of satellite-based measurements of SO2 in the atmosphere over Anatahan, using data from the UV spectrometers OMI, GOME-2, and SCIAMACHY, and the IR spectrometer AIRS. We find Anatahan's emissions to be highly variable both within and between intervals of eruption and quiescence. We demonstrate a close agreement between trends in SO2 emission evident from our remote sensing data and records of activity compiled from a range of other sources and instruments, across daily to annual temporal scales. Mean eruptive SO2 emissions at Anatahan are ~6400 t/d, and range from <1000 to >18000 t/d. Quiescent emissions are below our instrument detection limits and are therefore unlikely to exceed 150-300 t/d. Overall, accounting for both eruptive and quiescent emissions, we calculate a revised decadal mean SO2 emission rate of 1060-1200 t/d. We further calculate a total decadal SO2 yield from Anatahan of 4-5 Mt, significantly lower than the 17-34 Mt calculated if ground-based campaign data are used in isolation. The use of isolated measurements to extrapolate longer term emissions budgets is subject to clear uncertainty, and we argue that our satellite observations, covering a longer interval of Anatahan's history, are better suited to such calculations, and do not require widespread extrapolation. We propose that the use of multi-year satellite datasets, ideally in conjunction with key ground-based data and longterm records of activity, can make major improvements to existing emissions budgets at Anatahan and other volcanoes worldwide.

  8. 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.

  9. Volcano-ice-sea interaction in the Cerro Santa Marta area, northwest James Ross Island, Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Calabozo, Fernando M.; Strelin, Jorge A.; Orihashi, Yuji; Sumino, Hirochika; Keller, Randall A.

    2015-05-01

    We present here the results of detailed mapping, lithofacies analysis and stratigraphy of the Neogene James Ross Island Volcanic Group (Antarctic Peninsula) in the Cerro Santa Marta area (northwest of James Ross Island), in order to give constraints on the evolution of a glaciated volcanic island. Our field results included recognition and interpretation of seventeen volcanic and glacial lithofacies, together with their vertical and lateral arrangements, supported by four new unspiked K-Ar ages. This allowed us to conclude that the construction of the volcanic pile in this area took place during two main eruptive stages (Eruptive Stages 1 and 2), separated from the Cretaceous bedrock and from each other by two major glacial unconformities (U1 and U2). The U1 unconformity is related to Antarctic Peninsula Ice sheet expansion during the late Miocene (before 6.2 Ma) and deposition of glacial lithofacies in a glaciomarine setting. Following this glacial advance, Eruptive Stage 1 (6.2-4.6 Ma) volcanism started with subaerial extrusion of lava flows from an unrecognized vent north of the study area, with eruptions later fed from vent/s centered at Cerro Santa Marta volcano, where cinder cone deposits and a volcanic conduit/lava lake are preserved. These lava flows fed an extensive (> 7 km long) hyaloclastite delta system that was probably emplaced in a shallow marine environment. A second unconformity (U2) was related to expansion of a local ice cap, centered on James Ross Island, which truncated all the eruptive units of Eruptive Stage 1. Concomitant with glacier advance, renewed volcanic activity (Eruptive Stage 2) started after 4.6 Ma and volcanic products were fed again by Cerro Santa Marta vents. We infer that glaciovolcanic eruptions occurred under a moderately thin (~ 300 m) glacier, in good agreement with previous estimates of paleo-ice thickness for the James Ross Island area during the Pliocene.

  10. Imaging rapidly deforming ocean island volcanoes in the western Galpagos archipelago, Ecuador

    NASA Astrophysics Data System (ADS)

    Tepp, Gabrielle; Ebinger, Cynthia J.; Ruiz, Mario; Belachew, Manahloh

    2014-01-01

    Using local body wave arrival-time tomography methods to determine 3-D seismic velocity structure, we imaged the plumbing system of Sierra Negra Volcano, Galpagos. This hot spot volcanic chain includes some of the fastest deforming volcanoes in the world, making this an ideal location to study shield volcano plumbing systems. We inverted P and S wave arrivals recorded on a 15-station temporary array between July 2009 and June 2011 using an a priori 1-D velocity model constrained by offshore refraction studies. With local seismicity from nearby volcanoes as well as the ring fault system, the model resolution is good between depths of 3 and 15.5 km. The propagation of S waves throughout this volume argues against any large high-melt accumulations, although a shallow melt sill may exist above 5 km. We image a broad low-velocity region (>25 km laterally) below Sierra Negra at depths ~8-15 km. No large, regional velocity increase is found within the limits of good resolution, suggesting that crust is thicker than 15 km beneath the western Galpagos archipelago. Our results are consistent with crustal accretion of mafic cumulates from a large-volume magma chamber that may span the boundary between preplume and accreted crust. The similarity between our results and those of Hawaii leave open the possibility that the crust has also been thickened by under-plating.

  11. 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.

  12. Use of precipitation and groundwater isotopes to interpret regional hydrology on a tropical volcanic island: Kilauea volcano area, Hawaii

    USGS Publications Warehouse

    Scholl, M.A.; Ingebritsen, S.E.; Janik, C.J.; Kauahikaua, J.P.

    1996-01-01

    Isotope tracer methods were used to determine flow paths, recharge areas, and relative age for groundwater in the Kilauea volcano area of the Island of Hawaii. A network of up to 66 precipitation collectors was emplaced in the study area and sampled twice yearly for a 3-year period. Stable isotopes in rainfall show three distinct isotopic gradients with elevation, which are correlated with trade wind, rain shadow, and high- elevation climatological patterns. Temporal variations in precipitation isotopes are controlled more by the frequency of storms than by seasonal temperature fluctuations. Results from this study suggest that (1) sampling network design must take into account areal variations in rainfall patterns on islands and in continental coastal areas and (2) isotope/elevation gradients on other tropical islands may be predictable on the basis of similar climatology. Groundwater was sampled yearly in coastal springs, wells, and a few high-elevation springs. Areal contrasts in groundwater stable isotopes and tritium indicate that the volcanic rift zones compartmentalize the regional groundwater system, isolating the groundwater south of Kilauea's summit and rift zones. Part of the Southwest Rift gone appears to act as a conduit for water from higher elevation, but there is no evidence for downrift flow in the springs and shallow wells sampled in the lower East Rift Zone.

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

    NASA Astrophysics Data System (ADS)

    Mordret, Aurlien; Rivet, Diane; Lands, Matthieu; Shapiro, Nikola M.

    2015-01-01

    We cross correlate 4 years of seismic noise from the seismic network of Piton de la Fournaise Volcano (La Runion 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 Brl" areas and is an imprint of the solidified magma chamber of the dismantled "Les Alizs" 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.

  14. Real-time infrasonic monitoring of the eruption at a remote island volcano using seismoacoustic cross correlation

    NASA Astrophysics Data System (ADS)

    Nishida, Kiwamu; Ichihara, Mie

    2016-02-01

    On 2013 November 20, a submarine eruption started close to Nishinoshima island, which lies ˜1000 km south of Tokyo. Real-time monitoring of the eruption is crucial for understanding the formation processes of the new volcano island and related disaster prevention. In situ monitoring, however, is difficult in practice because the closest inhabited island, Chichijima, is 130 km away from Nishinoshima. This study presents an infrasonic monitoring method that uses cross-correlating records at a pair of online stations on Chichijima. One is the horizontal ground velocity recorded at a permanent seismic station operated by the Japan Meteorological Agency (JMA). The seismic records were corrected for atmospheric pressure using an empirical ground response to infrasound. The other is the air pressure recorded at the JMA Meteorological Observatory. For each station, we divided the whole records into 3600-s segments. To suppress outliers, each segment was normalized by the envelope function. We then calculated cross-correlation functions between the pair of stations using the fast Fourier transform. They present clear successive arrivals of infrasound coming from Nishinoshima. We also conducted an offline tripartite-array observation using three low-frequency microphones with a station spacing of ˜50 m installed in 2013 May. The array analysis supports the results obtained from the online stations. The typical root-mean-squared amplitude is on the order of 0.01 Pa, and the typical duration is several days. The amplitudes were primarily controlled by the effective sound velocity structure from Nishinoshima to Chichijima. The infrasonic observations together with the meteorological observation at Chichijima suggest that infrasonic activity was not present in the first two weeks in 2015 January. With the help of a more quantitative estimation of the meteorological effect, we could infer eruptive activity in real time. Now many online seismic stations are available worldwide. This study shows that installation of another infrasonic sensor close to the existing seismic station (˜1 km) is useful for monitoring a remote island volcano in real time.

  15. Boron isotopic composition of fumarolic condensates from some volcanoes in Japanese island arcs

    NASA Astrophysics Data System (ADS)

    Nomura, Masao; Kanzaki, Tadao; Ozawa, Takejiro; Okamoto, Makoto; Kakihana, Hidetake

    1982-11-01

    Boron samples from 40 fumarolic condensates from volcanoes in the Ryukyu arc (Satsuma Iwo-jima and Shiratori Iwo-yama) and the North-east Japan arc (Usu-shinzan, Showa-shinzan, Esan and Issaikyo-yama) all have 11B /10B ratios close to 4.07. Higher values, from 4.09 to 4.13, were only observed in condensates from volcanoes in the southernmost end of the North-east Japan arc (Nasu-dake), the northern part of the Izu-Bonin arc (Hakone), and the North Mariana arc (Ogasawara Iwo-jima). These higher values suggest geological interaction of the magmas with sea-water enriched in 11B.

  16. On the predictability of volcano-tectonic events by low frequency seismic noise analysis at Teide-Pico Viejo volcanic complex, Canary Islands

    NASA Astrophysics Data System (ADS)

    Trraga, M.; Carniel, R.; Ortiz, R.; Marrero, J. M.; Garca, A.

    2006-05-01

    The island of Tenerife (Canary Islands, Spain), is showing possible signs of reawakening after its last basaltic strombolian eruption, dated 1909 at Chinyero. The main concern relates to the central active volcanic complex Teide - Pico Viejo, which poses serious hazards to the properties and population of the island of Tenerife (Canary Islands, Spain), and which has erupted several times during the last 5000 years, including a subplinian phonolitic eruption (Montaa Blanca) about 2000 years ago. In this paper we show the presence of low frequency seismic noise which possibly includes tremor of volcanic origin and we investigate the feasibility of using it to forecast, via the material failure forecast method, the time of occurrence of discrete events that could be called Volcano-Tectonic or simply Tectonic (i.e. non volcanic) on the basis of their relationship to volcanic activity. In order to avoid subjectivity in the forecast procedure, an automatic program has been developed to generate forecasts, validated by Bayes theorem. A parameter called "forecast gain" measures (and for the first time quantitatively) what is gained in probabilistic terms by applying the (automatic) failure forecast method. The clear correlation between the obtained forecasts and the occurrence of (Volcano-)Tectonic seismic events - a clear indication of a relationship between the continuous seismic noise and the discrete seismic events - is the explanation for the high value of this "forecast gain" in both 2004 and 2005 and an indication that the events are Volcano-Tectonic rather than purely Tectonic.

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

    NASA Astrophysics Data System (ADS)

    Prates, G.; Garca, A.; Fernndez-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.

  18. 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.

  19. IESID: Automatic system for monitoring ground deformation on the Deception Island volcano (Antarctica)

    NASA Astrophysics Data System (ADS)

    Peci, Luis Miguel; Berrocoso, Manuel; Páez, Raúl; Fernández-Ros, Alberto; de Gil, Amós

    2012-11-01

    When establishing the relative distance between two GNSS-GPS stations with sub-centimeter accuracy, it is necessary to have auxiliary data, some of which can only be collected some time after the moment of measurement. However, for monitoring highly-active geodynamic areas, such as volcanoes and landslides, data precision is not as essential as rapid availability, processing of data in real-time, and fast interpretation of the results. This paper describes the development of an integrated automatic system for monitoring volcanic deformation in quasi real-time, applied to the Deception volcano (Antarctica). This experimental system integrates two independent modules that enable researchers to monitor and control the status of the GNSS-GPS stations, and to determine a surface deformation parameter. It comprises three permanent stations, one of which serves as the reference for assessing the relative distance in relation to the other two. The availability of GNSS-GPS data in quasi real-time is achieved by means of a WiFi infrastructure and automated data processing. This system provides, in quasi real-time, a time series of varying distances that tells us the extent to which any ground deformation is taking place.

  20. A large proportion of asymptomatic Plasmodium infections with low and sub-microscopic parasite densities in the low transmission setting of Temotu Province, Solomon Islands: challenges for malaria diagnostics in an elimination setting

    PubMed Central

    2010-01-01

    Background Many countries are scaling up malaria interventions towards elimination. This transition changes demands on malaria diagnostics from diagnosing ill patients to detecting parasites in all carriers including asymptomatic infections and infections with low parasite densities. Detection methods suitable to local malaria epidemiology must be selected prior to transitioning a malaria control programme to elimination. A baseline malaria survey conducted in Temotu Province, Solomon Islands in late 2008, as the first step in a provincial malaria elimination programme, provided malaria epidemiology data and an opportunity to assess how well different diagnostic methods performed in this setting. Methods During the survey, 9,491 blood samples were collected and examined by microscopy for Plasmodium species and density, with a subset also examined by polymerase chain reaction (PCR) and rapid diagnostic tests (RDTs). The performances of these diagnostic methods were compared. Results A total of 256 samples were positive by microscopy, giving a point prevalence of 2.7%. The species distribution was 17.5% Plasmodium falciparum and 82.4% Plasmodium vivax. In this low transmission setting, only 17.8% of the P. falciparum and 2.9% of P. vivax infected subjects were febrile (?38C) at the time of the survey. A significant proportion of infections detected by microscopy, 40% and 65.6% for P. falciparum and P. vivax respectively, had parasite density below 100/?L. There was an age correlation for the proportion of parasite density below 100/?L for P. vivax infections, but not for P. falciparum infections. PCR detected substantially more infections than microscopy (point prevalence of 8.71%), indicating a large number of subjects had sub-microscopic parasitemia. The concordance between PCR and microscopy in detecting single species was greater for P. vivax (135/162) compared to P. falciparum (36/118). The malaria RDT detected the 12 microscopy and PCR positive P. falciparum, but failed to detect 12/13 microscopy and PCR positive P. vivax infections. Conclusion Asymptomatic malaria infections and infections with low and sub-microscopic parasite densities are highly prevalent in Temotu province where malaria transmission is low. This presents a challenge for elimination since the large proportion of the parasite reservoir will not be detected by standard active and passive case detection. Therefore effective mass screening and treatment campaigns will most likely need more sensitive assays such as a field deployable molecular based assay. PMID:20822506

  1. Isolation, properties and amino acid sequences of a phospholipase A2 and its homologue without activity from the venom of a sea snake, Laticauda colubrina, from the Solomon Islands.

    PubMed

    Takasaki, C; Kimura, S; Kokubun, Y; Tamiya, N

    1988-08-01

    A phospholipase A2, Laticauda colubrina phospholipase A2 II (LcPLA-II), and a phospholipase A2 homologue, Laticauda colubrina phospholipase A2 homologue I (LcPLH-I), were isolated from the venom of the yellow-lipped sea snake, Laticauda colubrina, from the Solomon Islands. LcPLA-II showed phospholipase A2 activity towards egg-yolk phosphatidylcholine (24 mumol/min per mg at optimal conditions at 37 degrees C) and lethal potency (LD50 45 micrograms/kg body wt. intravenously in mice). Both of the activities were lost by treatment with p-bromophenacyl bromide. LcPLH-I showed neither phospholipase A2 activity nor lethal potency at a dose of 4.5 mg/kg body wt. in mice. It was not modified by the treatment with p-bromophenacyl bromide. LcPLA-II and LcPLH-I bound Ca2+ at a 1:1 molar ratio with KCa values of 105 microM and 44 microM at pH 8.0 respectively. Elucidation of the amino acid sequences of these two proteins showed that each protein consisted of a single chain of 118 amino acid residues, including 14 half-cystine residues. The two sequences are different from each other at 22 residues and highly homologous to those from other sources. The essential histidine residue for the phospholipase A2 activity at position 48 is replaced by an asparagine residue in the homologue LcPLH-I. Details of the separation of the peptides obtained by proteinase digestions of LcPLA-II and LcPLA-I and the determination of their amino acid sequences are given in Supplementary Publication SUP 50145 (14 pages), which has been deposited at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1988) 249, 5. PMID:3178739

  2. 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; Rstad, Anders; Garijo, Juan Carlos; Arstegui, Javier; Fraile-Nuez, Eugenio; Hernndez-Len, 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

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

    PubMed

    Ariza, Alejandro; Kaartvedt, Stein; Rstad, Anders; Garijo, Juan Carlos; Arstegui, Javier; Fraile-Nuez, Eugenio; Hernndez-Len, 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

  4. Towards a Proactive Risk Mitigation Strategy at La Fossa Volcano, Vulcano Island

    NASA Astrophysics Data System (ADS)

    Biass, S.; Gregg, C. E.; Frischknecht, C.; Falcone, J. L.; Lestuzzi, P.; di Traglia, F.; Rosi, M.; Bonadonna, C.

    2014-12-01

    A comprehensive risk assessment framework was built to develop proactive risk reduction measures for Vulcano Island, Italy. This framework includes identification of eruption scenarios; probabilistic hazard assessment, quantification of hazard impacts on the built environment, accessibility assessment on the island and risk perception study. Vulcano, a 21 km2 island with two primary communities host to 900 permanent residents and up to 10,000 visitors during summer, shows a strong dependency on the mainland for basic needs (water, energy) and relies on a ~2 month tourism season for its economy. The recent stratigraphy reveals a dominance of vulcanian and subplinian eruptions, producing a range of hazards acting at different time scales. We developed new methods to probabilistically quantify the hazard related to ballistics, lahars and tephra for all eruption styles. We also elaborated field- and GIS- based methods to assess the physical vulnerability of the built environment and created dynamic models of accessibility. Results outline the difference of hazard between short and long-lasting eruptions. A subplinian eruption has a 50% probability of impacting ~30% of the buildings within days after the eruption, but the year-long damage resulting from a long-lasting vulcanian eruption is similar if tephra is not removed from rooftops. Similarly, a subplinian eruption results in a volume of 7x105 m3 of material potentially remobilized into lahars soon after the eruption. Similar volumes are expected for a vulcanian activity over years, increasing the hazard of small lahars. Preferential lahar paths affect critical infrastructures lacking redundancy, such as the road network, communications systems, the island's only gas station, and access to the island's two evacuation ports. Such results from hazard, physical and systemic vulnerability help establish proactive volcanic risk mitigation strategies and may be applicable in other island settings.

  5. Vapor deposition of trace elements from degassed basaltic lava, Piton de la Fournaise volcano, Reunion Island

    NASA Astrophysics Data System (ADS)

    Toutain, J. P.; Aloupogiannis, P.; Delorme, H.; Person, A.; Blanc, P.; Robaye, G.

    1990-04-01

    Silica-tube sublimates resulting from the cooling of high-temperature volcanic gases from degassed lava in lava tunnels have been sampled at Piton de la Fournaise volcano. Mineral phases deposited in the tube are mainly halides (Na, K and Cu chlorides, Si and K fluorides). The distribution of most of the chemical elements as a function of the temperature is mainly controlled by their volatility. Volatile elements such as Rb, Cs, Se, Pb and Tl are associated with low-temperature deposits, whereas refractory elements such as R.E.E., alkaline earth, Sc, Ta, Hf, Th and Zr are not detected. The mineral assemblages are characterized by the lack of sulfides, sulfates, native sulfur and oxides. In the same way, numerous transition and semi-metallic elements are lacking. This is interpreted as the result of the magma transport in surface lava tunnels, leading to extensive degassing upstream of the collection site.

  6. Tilt recorded by a portable broadband seismograph: The 2003 eruption of Anatahan Volcano, Mariana Islands

    USGS Publications Warehouse

    Wiens, D.A.; Pozgay, S.H.; Shore, P.J.; Sauter, A.W.; White, R.A.

    2005-01-01

    The horizontal components of broadband seismographs are highly sensitive to tilt, suggesting that commonly deployed portable broadband seismic sensors may record important tilt information associated with volcanic eruptions. We report on a tilt episode that coincides with the first historical eruption of Anatahan volcano on May 10, 2003. The tilt was recorded by a Strekheisen STS-2 seismograph deployed in an underground insulated chamber 7 km west of the active vent. An ultra-long period signal with a dominant period of several hours was recorded on the E-W component beginning at 06:20 GMT on May 10, which coincides with the onset of continuous volcano-tectonic (VT) seismicity and is one hour prior to the eruption time estimated by the Volcanic Ash Advisory Center. The signal is much smaller on the N-S component and absent on the vertical component, suggesting it results from tilt that is approximately radial with respect to the active vent. An estimate of tilt as a function of time is recovered by deconvolving the record to acceleration and dividing by the acceleration of gravity. The record indicates an initial episode of tilt downward away from the volcanic center from 06:20-09:30 GMT, which we interpret as inflation of the shallow volcanic source. The tilt reverses, recording deflation, from 09:30 until 17:50, after which the tilt signal becomes insignificant. The inflation corresponds to a period of numerous VT events, whereas fewer events were recorded during the deflation episode, and the VT events subsequently resumed after the end of the deflationary tilt. The maximum tilt of 2 microradians can be used to estimate the volume of the source inflation (???2 million in m3), assuming a simple Mogi source model. These calculations are consistent with other estimates of source volume if reasonable source depths are assumed. Examination of broadband records of other eruptions may disclose further previously unrecognized tilt signals. Copyright 2005 by the American Geophysical Union.

  7. Geomorphic evolution of the Piton des Neiges volcano (Réunion Island, Indian Ocean): Competition between volcanic construction and erosion since 1.4 Ma

    NASA Astrophysics Data System (ADS)

    Salvany, Tiffany; Lahitte, Pierre; Nativel, Pierre; Gillot, Pierre-Yves

    2012-01-01

    Réunion Island (Indian Ocean) is a volcanic complex whose eruptive history was dominated by the activity of two main edifices: Piton des Neiges (PN) and Piton de la Fournaise (PF) volcanoes. The tropical climate induces erosion processes that permanently compete with volcanic constructional processes. Exposed to the trade winds and associated heavy rainfalls, the northeastern part of the island exhibits the most complex morphological evolution. Geomorphological analysis, performed on a 50 m DEM and associated to new K-Ar ages has clarified the overall history of PN volcano. Each massif is assigned to one of the main building stages of the edifice. In addition, the arrangement of these different massifs reveals that the eruptive phases have led to successive relief inversions and successive excavations of large central depressions in the proximal area. As a result, the younger massifs are always located in more proximal parts of the volcano, the youngest being close to the edifice center. In distal areas, early lava flows were channeled into valleys incised along the massif boundaries, leading to a more complex geochronological organization. Quantitative study of the dissection of PN volcano allows us to propose a minimum eroded volume of 101 ± 44 and 105 ± 41 km 3 for the Mafate and Cilaos "Cirques" (depressions), respectively, during the last 180 kyr and a minimum average long-term erosion rate of 1.2 ± 0.4 km 3/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km 3) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing geomorphic process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major process in the morphological evolution of Réunion Island that has to be fully integrated in future studies.

  8. Long- and short-term temporal variations of the diffuse CO2 emission from Timanfaya volcano, Lanzarote, Canary Islands

    NASA Astrophysics Data System (ADS)

    Hernndez, P. A.; Padilla, G.; Calvo, D.; Padrn, E.; Melian, G.; Dionis, S.; Nolasco, D.; Barrancos, J.; Rodrguez, F.; Prez, N.

    2012-04-01

    Lanzarote Island is an emergent part of the East Canary Ridge and it is situated approximately 100 km from the NW coast of Morocco, covering an area of about 795km2. The largest historical eruption of the Canary Islands, Timanfaya, took place during 1730-36 in this island when long-term eruptions from a NE-SW-trending fissure formed the Montaas del Fuego. The last eruption at Lanzarote Island occurred during 1824, Tinguaton volcano, and produced a much smaller lava flow that reached the SW coast. At present, one of the most prominent phenomena at Timanfaya volcanic field is the high maintained superficial temperatures occurring in the area since the 1730 volcanic eruption. The maximum temperatures recorded in this zone are 605C, taken in a slightly inclined well 13 m deep. Since fumarolic activity is absent at the surface environment of Lanzarote, to study the diffuse CO2 emission becomes an ideal geochemical tool for monitoring its volcanic activity. Soil CO2 efflux surveys were conducted throughout Timanfaya volcanic field and surrounding areas during the summer periods of 2006, 2007, 2008, 2009, fall period of 2010 and winter, spring and summer periods of 2011 to investigate long and short-term temporal variations of the diffuse CO2 emission from Timanfaya volcano. Soil CO2 efflux surveys were undertaken at Timanfaya volcanic field always under stable weather conditions to minimize effects of meteorological conditions on the CO2 at the soil atmosphere. Approximately 370-430 sampling sites were selected at the surface environment of Timanfaya to obtain an even distribution of the sampling points over the study area. The accumulation chamber method (Parkinson et al., 1981) was used to perform soil CO2 efflux measurements in-situ by means of a portable non dispersive infrared (NDIR) CO2 analyzer, which was interfaced to a hand size computer that runs data acquisition software. At each sampling site, soil temperature at 15 and 40cm depth was also measured by means of a thermocouple together with soil gas samples collected during the campaign of 2010 to evaluate the chemical and isotopic composition of soil gases. Diffuse CO2 emission values have ranged between non detectable values to 34 g m-2 d-1, and most of the study area have shown relatively low values, around the detection limit of the instrument (~0,5 g m-2 d-1). Higher soil CO2 diffuse emission values were observed where thermal anomalies occur, indicating a convective mechanism transport of gas from depth at these areas. Total CO2 outputs of the study area have been estimated in the range 41-518 t d-1 during the study period. Long-term temporal variation on total CO2 diffuse emission shows a peak recorded on winter 2011, suggesting a seasonal control on the CO2 emission. As part of the volcanic surveillance program and to understand the dynamics of CO2 diffuse emission at Timanfaya volcanic zone, an automatic geochemical station was installed in July 2010 to monitor the CO2 emission and investigate the short-term temporal variation. Time series of soil CO2 efflux shows also a close relationship with seasonal changes mainly due to rainfall.

  9. Major and rare gases at White Island Volcano, New Zealand: Origin and flux of volatiles

    SciTech Connect

    Marty, B. ); Giggenbach, W.F. )

    1990-03-01

    Analyses of fumarolic gases at White Island, New Zealand, are reported with special emphasis on rare gases (He, Ne, Ar, Kr and Xe). Normalization of major species to rare gases have lead to the identification of several sources: air-saturated meteoric (or marine) water, a magma body, the crust and/or sediments. When compared to Mid Ocean Ridge discharges, the White Island gas discharge represents about 3%, 0.7%, 0.1% and 0.05% of the global water, carbon, sulfur and Helium-3 discharges, respectively. This balance shows that, except for {sup 3}He which derives from the mantle, practically all rare gases, water and carbon, and part of sulfur, derive from originally superficial sources.

  10. Volcano-tectonic implications of 3-D velocity structures derived from joint active and passive source tomography of the island of Hawaii

    USGS Publications Warehouse

    Park, J.; Morgan, J.K.; Zelt, C.A.; Okubo, P.G.

    2009-01-01

    We present a velocity model of the onshore and offshore regions around the southern part of the island of Hawaii, including southern Mauna Kea, southeastern Hualalai, and the active volcanoes of Mauna Loa, and Kilauea, and Loihi seamount. The velocity model was inverted from about 200,000 first-arrival traveltime picks of earthquakes and air gun shots recorded at the Hawaiian Volcano Observatory (HVO). Reconstructed volcanic structures of the island provide us with an improved understanding of the volcano-tectonic evolution of Hawaiian volcanoes and their interactions. The summits and upper rift zones of the active volcanoes are characterized by high-velocity materials, correlated with intrusive magma cumulates. These high-velocity materials often do not extend the full lengths of the rift zones, suggesting that rift zone intrusions may be spatially limited. Seismicity tends to be localized seaward of the most active intrusive bodies. Low-velocity materials beneath parts of the active rift zones of Kilauea and Mauna Loa suggest discontinuous rift zone intrusives, possibly due to the presence of a preexisting volcanic edifice, e.g., along Mauna Loa beneath Kilauea's southwest rift zone, or alternatively, removal of high-velocity materials by large-scale landsliding, e.g., along Mauna Loa's western flank. Both locations also show increased seismicity that may result from edifice interactions or reactivation of buried faults. New high-velocity regions are recognized and suggest the presence of buried, and in some cases, previously unknown rift zones, within the northwest flank of Mauna Loa, and the south flanks of Mauna Loa, Hualalai, and Mauna Kea. Copyright 2009 by the American Geophysical Union.

  11. Volcano-tectonic implications of 3-D velocity structures derived from joint active and passive source tomography of the island of Hawaii

    NASA Astrophysics Data System (ADS)

    Park, Jaewoo; Morgan, Julia K.; Zelt, Colin A.; Okubo, Paul G.

    2009-09-01

    We present a velocity model of the onshore and offshore regions around the southern part of the island of Hawaii, including southern Mauna Kea, southeastern Hualalai, and the active volcanoes of Mauna Loa, and Kilauea, and Loihi seamount. The velocity model was inverted from about 200,000 first-arrival traveltime picks of earthquakes and air gun shots recorded at the Hawaiian Volcano Observatory (HVO). Reconstructed volcanic structures of the island provide us with an improved understanding of the volcano-tectonic evolution of Hawaiian volcanoes and their interactions. The summits and upper rift zones of the active volcanoes are characterized by high-velocity materials, correlated with intrusive magma cumulates. These high-velocity materials often do not extend the full lengths of the rift zones, suggesting that rift zone intrusions may be spatially limited. Seismicity tends to be localized seaward of the most active intrusive bodies. Low-velocity materials beneath parts of the active rift zones of Kilauea and Mauna Loa suggest discontinuous rift zone intrusives, possibly due to the presence of a preexisting volcanic edifice, e.g., along Mauna Loa beneath Kilauea's southwest rift zone, or alternatively, removal of high-velocity materials by large-scale landsliding, e.g., along Mauna Loa's western flank. Both locations also show increased seismicity that may result from edifice interactions or reactivation of buried faults. New high-velocity regions are recognized and suggest the presence of buried, and in some cases, previously unknown rift zones, within the northwest flank of Mauna Loa, and the south flanks of Mauna Loa, Hualalai, and Mauna Kea.

  12. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2001-01-01

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

  13. Observations on basaltic lava streams in tubes from Kilauea Volcano, island of Hawai'i

    USGS Publications Warehouse

    Kauahikaua, J.; Cashman, K.V.; Mattox, T.N.; Christina, Heliker C.; Hon, K.A.; Mangan, M.T.; Thornber, C.R.

    1998-01-01

    From 1986 to 1997, the Pu'u 'O'o-Kupaianaha eruption of Kilauea produced a vast pahoehoe flow field fed by lava tubes that extended 10-12 km from vents on the volcano's east rift zone to the ocean. Within a kilometer of the vent, tubes were as much as 20 m high and 10-25 m wide. On steep slopes (4-10??) a little farther away from the vent, some tubes formed by roofing over of lava channels. Lava streams were typically 1-2 m deep flowing within a tube that here was typically 5 m high and 3 m wide. On the coastal plain (<1??), tubes within inflated sheet flows were completely filled, typically 1-2 m high, and several tens of meters wide. Tubes develop as a flow's crust grows on the top, bottom, and sides of the tubes, restricting the size of the fluid core. The tubes start out with nearly elliptical cross-sectional shapes, many times wider than high. Broad, flat sheet flows evolve into elongate tumuli with an axial crack as the flanks of the original flow were progressively buried by breakouts. Temperature measurements and the presence of stalactites in active tubes confirmed that the tube walls were above the solidus and subject to melting. Sometimes, the tubes began downcutting. Progressive downcutting was frequently observed through skylights; a rate of 10 cm/d was measured at one skylight for nearly 2 months.

  14. Extreme Spatial Variability in Microbial Mat Communities from Submarine Hydrothermal Vents Located at Multiple Volcanoes along the Mariana Island Arc

    NASA Astrophysics Data System (ADS)

    Davis, R. E.; Moyer, C. L.

    2005-12-01

    Volcanic arc systems are the most active tectonic feature in the world, but are among the least studied. The Western Pacific contains ~20,000 km of volcanic arcs, of which only ~2% have been systematically surveyed. The lack of comprehensive knowledge of volcanic arcs is compounded by the incredible variability found in relatively short distances. The complex source history of hydrothermal fluids and the variable depths of seamounts found in island arc systems result in highly variable vent chemistries and therefore unique microbial habitats within relatively short distances. The Mariana Island Arc was surveyed in 2003 and areas with suspected hydrothermal activities were identified for targeted remote operating vehicle (ROV) exploration and sampling in 2004. Sixteen microbial mat samples from five seamounts ranging from 145-1742 mbsl and from ambient to 222C were collected and analyzed with quantitative PCR (Q-PCR), cluster analysis of terminal restriction length polymorphism (T-RFLP) community fingerprints, and by clone library analysis of small subunit ribosomal rDNA genes. The microbial mat communities from the Mariana Island Arc exhibit greater spatial variability within their community structure than microbial mats sampled from mid-ocean ridge or hotspot hydrothermal vents from a comparable scale. Microbial communities from the summit of NW Eifuku Volcano are dominated by putative iron-oxidizing phylotypes at the Yellow Top and Yellow Cone Vent sites, but are dominated by sulfur-oxidizing ?-Proteobacteria at the Champagne Vent site. Mats collected at the Mat City Vent site on E Diamante Seamount contained nearly three times as much biomass as any other mat sample collected, and is dominated by a Planctomyces phylotype. Hydrothermal sediments at the Fish Spa site located on Daikoku Seamount contained the second highest biomass detected and supported a large community of flatfish indicating a direct route for biomass being channeled up the food chain. The microbial community at Fish Spa consists of a highly diverse assemblage of Bacteroidetes, ?-Proteobacteria and Firmicutes. While in contrast, the microbial mat at the Iceberg Vent site on NW Rota I is dominated by a single phylotype of ?-Proteobacteria.

  15. 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.

  16. 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...

  17. Volcano-tectonic evolution of the Santa Maria Island (Azores): Implications for paleostress evolution at the western Eurasia-Nubia plate boundary

    NASA Astrophysics Data System (ADS)

    Sibrant, A. L. R.; Hildenbrand, A.; Marques, F. O.; Costa, A. C. G.

    2015-01-01

    The growth and decay of oceanic volcanoes developed close to plate boundaries are intrinsically related to a competition between construction and destruction processes, partly controlled by tectonic strain and stresses. From morphologic, stratigraphic, tectonic and new high-precision K-Ar data, we present a comprehensive picture of the volcano-tectonic evolution of Santa Maria, and discuss its significance regarding the stress evolution and regional deformation in the Azores. Our new data show that: (1) the western flat portion of the island is mostly composed of west-dipping volcanic rocks here dated between 5.70 ± 0.08 and 5.33 ± 0.08 Ma, which we consider the remnants of an Older Shield Volcano; (2) more than half of this early volcanic complex has been removed by an east-directed large-scale sector collapse; (3) a second volcano, here coined the Younger Shield Volcano, grew rapidly on the collapse scar between at least 4.32 ± 0.06 and 3.94 ± 0.06 Ma; (4) more than half of this new volcano was removed by a second large-scale sector collapse most probably around 3.6 Ma, based on the ages of Parasitic Scoria Cones sitting unconformably on the Younger Shield Volcano; (5) the latest parasitic volcanic activity is here dated at 2.84 ± 0.04 Ma, extending significantly the known eruptive history of Santa Maria. Morpho-structural data (shape of the island, faults, dikes, and distribution of volcanic cones) show a significant control of construction and destruction along the N045° and N150° directions. The age of the lavas intruded by dikes suggests that the N045° and the N150° trends are ca. 5.3 Ma old and younger than ca. 4.3 Ma, respectively. Based on the new data, we conclude that a change in the regional stress field occurred between 5.3 and 4.3 Ma, most likely associated with a major reconfiguration of the Eurasia/Nubia plate boundary in the Azores.

  18. Transient volcano deformation sources imaged with interferometric synthetic aperture radar: Application to Seguam Island, Alaska

    USGS Publications Warehouse

    Masterlark, Timothy; Lu, Zhong

    2004-01-01

    Thirty interferometric synthetic aperture radar (InSAR) images, spanning various intervals during 19922000, document coeruptive and posteruptive deformation of the 19921993 eruption on Seguam Island, Alaska. A procedure that combines standard damped least squares inverse methods and collective surfaces, identifies three dominant amorphous clusters of deformation point sources. Predictions generated from these three point source clusters account for both the spatial and temporal complexity of the deformation patterns of the InSAR data. Regularized time series of source strength attribute a distinctive transient behavior to each of the three source clusters. A model that combines magma influx, thermoelastic relaxation, poroelastic effects, and petrologic data accounts for the transient, interrelated behavior of the source clusters and the observed deformation. Basaltic magma pulses, which flow into a storage chamber residing in the lower crust, drive this deformational system. A portion of a magma pulse is injected into the upper crust and remains in storage during both coeruption and posteruption intervals. This injected magma degasses and the volatile products accumulate in a shallow poroelastic storage chamber. During the eruption, another portion of the magma pulse is transported directly to the surface via a conduit roughly centered beneath Pyre Peak on the west side of the island. A small amount of this magma remains in storage during the eruption, and posteruption thermoelastic contraction ensues. This model, made possible by the excellent spatial and temporal coverage of the InSAR data, reveals a relatively simple system of interrelated predictable processes driven by magma dynamics.

  19. Changes of diffuse CO2 emission from the summit cone of Teide volcano, Tenerife, Canary Islands: a premonitory volcanic unrest signature?

    NASA Astrophysics Data System (ADS)

    Padilla, G.; Perez, N.; Hernandez Perez, P. A.; Padron, E.; Melian, G.; Nolasco, D.; Barrancos, J.; Marrero, R.; Calvo, D.; Diaz Requejo, M.; Rodriguez, F.; Chiodini, G.

    2009-12-01

    We report the results of 11 soil CO2 efflux surveys by the accumulation chamber method at the summit cone of Teide volcano (SCT), Tenerife Island, Spain. The surveys were undertaken from 1997 to 2009 to determine the scale of total CO2 emissions at the SCT and to evaluate the temporal and spatial variations of CO2 efflux and their relationships with the volcanic-seismic activity at Tenerife. Our results reveal significant variations from 1997 to 2009 and indicate that CO2 emissions at the SCT fluctuate greatly. Temporal variations in the total CO2 output do not seem to be masked by external variations, showing a temporal correlation with the onsets of seismic activity in 2004. The fluctuations are evident in the intensity of the efflux anomaly. These geochemical observations support unrest of the volcanic system, as is also suggested by anomalous seismic activity recorded in Tenerife Island during April 22-29, 2004 (Spanish National Geographical Institute, IGN). A new increasing trend is observed from 2007, which might precursor new anomalous seismic activity in the next future, suggesting that subsurface magma movement is the cause for the observed changes in the total output of diffuse CO2 emission. Performing frequent soil CO2 efflux surveys appear to be an effective surveillance tool for Teide volcanic system at Tenerife Island. The temporal evolution of the diffuse CO2 emissions from SCT will allow us to determine the typical range of seasonal or other transient departures from its normal or baseline behaviour. For this reason, ITERs Teide Geochemical Monitoring Program has become an important tool since 1997 for reducing volcano risk in Tenerife Island, making a special effort on volcano monitoring to detect precursory phenomena which provide early warnings of possible impending eruptions.

  20. 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.

  1. B-type volcanic earthquakes at White Island volcano, New Zealand

    NASA Astrophysics Data System (ADS)

    Sherburn, Steven; Scott, Bradley J.

    1993-08-01

    B-type volcanic earthquakes at White Island have almost all their energy in the band 0.5-4 Hz, around a dominant spectral peak of about 2 Hz. A high degree of similarity in the waveforms suggests that the earthquakes originate from a volume of about 100 m 3, and that the process that generates them is repetitive. At a distance of 1 km from the active crater the particle motion of B-type events suggests an initial P-wave, followed 0.5 seconds later by a horizontally polarised S-wave and then a wave of unknown type. The exact mechanism for B-type events is unknown, however, the absence of higher harmonics implies they cannot be caused by the resonance of gas or magma within a pipe-like structure, and the P- and S-waves suggest a simple shear-induced rock fracture in a hot ductile medium.

  2. Chronic exposure to volcanic air pollution and DNA damage in Furnas Volcano (São Miguel Island, Azores, Portugal) inhabitants

    NASA Astrophysics Data System (ADS)

    Linhares, Diana; Garcia, Patricia; Silva, Catarina; Ferreira, Teresa; Barroso, Joana; Camarinho, Ricardo; Rodrigues, Armindo

    2015-04-01

    Many studies in volcanic air pollution only have in consideration the acute toxic effects of gas or ash releases however the impact of chronic exposure to ground gas emissions in human health is yet poorly known. In the Azores archipelago (Portugal), São Miguel island has one of the most active and dangerous volcanoes: Furnas Volcano. Highly active fumarolic fields, hot springs and soil diffuse degassing phenomena are the main secondary volcanic phenomena that can be seen at the volcano surroundings. One of the main gases released in these diffuse degassing areas is radon (222Rn), which decay results in solid particles that readily settle within the airways. These decay particles emit alpha radiation that is capable of causing severe DNA damage that cumulatively can eventually cause cancer. Previous studies have established that chronic exposure to chromosome-damaging agents can lead to the formation of nuclear anomalies, such as micronuclei that is used for monitoring DNA damage in human populations. The present study was designed to evaluate whether chronic exposure to volcanic air pollution, associated to 222Rn, might result in DNA damage in human oral epithelial cells. A cross sectional study was performed in a study group of 142 individuals inhabiting an area where volcanic activity is marked by active fumarolic fields and soil degassing (hydrothermal area), and a reference group of 368 individuals inhabiting an area without these secondary manifestations of volcanism (non-hydrothermal area). For each individual, 1000 buccal epithelial cells were analyzed for the frequency of micronucleated cells (MNc) and the frequency of cells with other nuclear anomalies (ONA: pyknosis, karyolysis and karyorrhexis), by using the micronucleus assay. Information on lifestyle factors and an informed consent were obtained from each participant. Assessment of indoor radon was performed with the use of radon detectors. Data were analyzed with logistic regression models, adjusted for confounding factors (age, gender, smoking and drinking status, and number of cigarettes smoked per day). Results demonstrated that levels of radon in the environment were significantly different in study and reference groups (115 Bq/m3 vs. 47 Bq/m3, respectively; p<0.001); in winter, radon measurements reached the highest values both in the study and the reference groups (809 Bq/m3 vs. 56 Bq/m3, respectively). The frequency of MNc in the study group was significantly higher than in the reference group (2.93‰ vs. 2.58‰, respectively; p=0.002). The OR for formation of MNc in the hydrothermal area was 1.5 (95% CI 1.07-2.02). A moderate and positive correlation was found between the frequency of MNc and 222Rn (rs = 0.459, p<0.001). To our knowledge this is the first study that clearly associates the exposure of volcanogenic indoor radon in inhabitants of hydrothermal areas and the DNA damage in human oral epithelial cells, evidencing that volcanic air pollution is a risk factor of carcinogenesis. Although the present findings require confirmation in larger studies, bio-monitoring for DNA damage is recommended for inhabitants of localities with active volcanism and mitigation measures such as restriction of building in certain areas should be taken into consideration in these volcanically active areas.

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

    NASA Astrophysics Data System (ADS)

    Vlastlic, I.; Staudacher, T.; Deniel, C.; Devidal, J. L.; Devouard, B.; Finizola, A.; Tlouk, 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.

  4. 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.

  5. The 2007 eruptions and caldera collapse of the Piton de la Fournaise volcano (La Réunion Island) from tilt analysis at a single very broadband seismic station

    NASA Astrophysics Data System (ADS)

    Fontaine, Fabrice R.; Roult, Geneviève; Michon, Laurent; Barruol, Guilhem; Muro, Andrea Di

    2014-04-01

    Seismic records from La Réunion Island very broadband Geoscope station are investigated to constrain the link between the 2007 eruptive sequence and the related caldera collapse of the Piton de la Fournaise volcano. Tilt estimated from seismic records reveals that the three 2007 eruptions belong to a single inflation-deflation cycle. Tilt trend indicates that the small-volume summit eruption of 18 February occurred during a phase of continuous inflation that started in January 2007. Inflation decelerated 24 days before a second short-lived, small-volume eruption on 30 March, almost simultaneous with a sudden, large-scale deflation of the volcano. Deflation rate, which had stabilized at relatively low level, increased anew on 1 April while no magma was erupted, followed on 2 April by a major distal eruption and on 5 April by a summit caldera collapse. Long-term tilt variation suggests that the 2007 eruptive succession was triggered by a deep magma input.

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

    NASA Astrophysics Data System (ADS)

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

    1990-09-01

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

  7. Deformation studies at Furnas and Sete Cidades Volcanoes (So Miguel Island, Azores). Velocities and further investigations

    NASA Astrophysics Data System (ADS)

    Trota, A.; Houli, N.; Briole, P.; Gaspar, J. L.; Sigmundsson, F.; Feigl, K. L.

    2006-08-01

    The Azores archipelago is located near the triple junction between the Nubian (NU), North America (NA), and Eurasia (EU) plates. It is characterized by a relatively strong seismicity and active volcanism. The best estimate of the current plate velocities in the area over geologic timescales comes from the NUVEL1-NNR model (DeMets et al.) . At the geodetic timescale, plate motion models (Altamimi et al., Sella et al.) including GPS, DORIS, SLR and VLBI data currently do not yet include data from the Azores. In the framework of a research project focused on the seismotectonics and volcanotectonics of So Miguel island, we have analysed GPS data collected there in 1993, 1994, 1997, 2000 and 2002. Our analysis determines both the velocity in the REVEL (Sella et al.) reference frame of So Miguel and its internal deformation. The comparison of the 2000 and 2002 coordinates indicates that So Miguel accommodates moderate WNW-ESE extension at a rate slower than 5 mm yr-1.

  8. 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 (Kl 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. Klgel, 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).

  9. 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.

  10. 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.

  11. Flow-By-Flow Mapping on Fogo, Cape Verde Islands, Reveals Long Term Variations in Eruption Distributions and Volcanic Edifice Structure at a Shield-Stage Oceanic Island Volcano

    NASA Astrophysics Data System (ADS)

    Day, S. J.

    2011-12-01

    Most maps of large oceanic island shield volcanoes show the lava flows and scoria cones of individual historic and subhistoric eruptions as individual units but then resort to grouping older rocks into larger stratigraphic units. This grouping makes it difficult to characterize long-term progressive trends in volumes of individual eruptions and distributions of eruptive vents, but is commonly made necessary by poor exposure, limited compositional variation between individual eruptions, and burial of older by younger volcanic rocks. In contrast, work on Fogo, Cape Verde Islands has involved flow-by-flow mapping of rocks erupted over an extended period of tens of thousands of years, as part of the process of mapping the island and producing a 1:25 000 scale geological map for research and hazard management purposes. Around three-quarters of the island is characterized by low rainfall and limited vegetation cover, with erosion restricted to narrow gullies. Only in small areas on the windward side of the island do higher rainfall, thick vegetation and deeper erosion combine to prevent flow-by-flow mapping. The map of the island is accompanied by a rigorous representation of direct and inferred age relationships between lavas and scoria cones of different eruptions using a novel type of age correlation diagram. The time period covered by the flow-by-flow mapping includes both the final stages of growth of an older shield volcano (Monte Amarelo volcano) prior to its collapse and the subsequent growth of a new volcano (Cha das Caldeiras volcano). The latter forms a thick infill and summit cone within the Monte Amarelo collapse scar together with partial covering of the outer flanks of the Monte Amarelo volcano with a veneer of younger lavas and scoria cones. The erupted rocks are compositionally varied (ankaramitic nephelinites, basanites, tephrites) and often highly porphyritic. Petrographic criteria were therefore used to aid field mapping, define lithostratigraphic units and demonstrate systematic changes in compositions of erupted magmas through time. Some of these changes, particularly eruptions of ankaramitic magmas, coincide with similar sequences of volcano-structural changes that have occurred prior to the Monte Amarelo collapse and again during the Holocene (beginning around 11 000 years before present; Foeken et al, 2009). The flow-by-flow mapping approach has allowed reconstruction and comparison of the sequences of these structural changes, and thus provides insights into the inferred progressive destabilization of the eastern flank of Fogo during the Holocene, as well as into wide variations in eruption and resurfacing rates that have occurred on decade to century timescales in more recent times. Foeken, J.P.T., Day, S.J. & Stuart, F.M. (2009) Cosmogenic 3He exposure dating of the Quaternary basalts from Fogo, Cape Verdes: Implications for rift zone and magmatic reorganization. Quaternary Geology 4 (2009) 37 - 49.

  12. 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.

  13. Influence of an ocean on the propagation of magmas within an oceanic basaltic shield volcano

    NASA Astrophysics Data System (ADS)

    Le Corvec, Nicolas; McGovern, Patrick

    2015-04-01

    Basaltic shield volcanoes are a common feature on Earth and mostly occur within oceans, forming volcanic islands (e.g. Hawaii (USA), Galapagos (Ecuador), and recently Niijima (Japan)). As the volcano grows it will reach and emerge from the water surface and continue to grow above it. The deformation affecting the volcanic edifice may be influenced by the presence of the water level. We investigate how the presence of an ocean affects the state of stress within a volcanic edifice and thus magma propagation and fault formation. Using COMSOL Multiphysics, axisymmetric elastic models of a volcanic edifice overlying an elastic lithosphere were created. The volcanic edifice (height of ~6000 m and radius of ~ 60 km) was built either instantaneously or iteratively by adding new layers of equivalent volume on top of each other. In the later process, the resulting stress and geometry from the one step is transferred to the next as initial conditions. Thus each new layer overlies a deformed and stressed model. The water load was modeled with a boundary condition at the surface of the model. In the case of an instantaneous volcano different water level were studied, for an iteratively growing volcano the water level was set up to 4000 m. We compared the deformation of the volcanic edifice and lithosphere and the stress orientation and magnitude in half-space and flexural models with the presence or not of an ocean. The preliminary results show 1- major differences in the resulting state of stress between an instantaneous and an iteratively built volcanic edifice, similar to the results of Galgana et al. (2011) and McGovern and Solomon (1993), respectively; 2- the presence of an ocean decreases the amount of flexural response, which decreases the magnitude of differential stress within the models; and 3- stress orientation within the volcano and lithosphere in also influence of an ocean. Those results provide new insights on the state of stress and deformation of oceanic basaltic volcanic edifices. Galgana, G. A., P. J. McGovern, and E. B. Grosfils (2011), Evolution of large Venusian volcanoes: Insights from coupled models of lithospheric flexure and magma reservoir pressurization, J. Geophys. Res., 116(E3), E03009. McGovern, P. J., and S. C. Solomon (1993), State of stress, faulting, and eruption characteristics of large volcanoes on Mars, Journal of Geophysical Research: Planets, 98(E12), 23553-23579.

  14. 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.

  15. Intra- and extra-caldera volcaniclastic facies and geomorphic characteristics of a frequently active mafic island-arc volcano, Ambrym Island, Vanuatu

    NASA Astrophysics Data System (ADS)

    Nmeth, Kroly; Cronin, Shane J.; Stewart, Robert B.; Charley, Douglas

    2009-10-01

    Ambrym is one of the most voluminous active volcanoes in the Melanesian arc. It consists of a 35 by 50 km island elongated east-west, parallel with an active fissure zone. The central part of Ambrym, about 800 m above sea level, contains a 12 kilometre-wide caldera, with two active intra-caldera cone-complexes, Marum and Benbow. These frequently erupting complexes provide large volumes of tephra (lapilli and ash) to fill the surrounding caldera and create an exceptionally large devegetated plateau "ash plain", as well as sediment-choked fluvial systems leading outward from the summit caldera. Deposits from fall, subordinate base surge and small-volume pyroclastic (scoria) flows dominate the volcaniclastic sequences in near vent regions. Frequent and high-intensity rainfall results in rapid erosion of freshly deposited tephra, forming small-scale debris flow- and modified grain flow-dominated deposits. Box-shaped channel systems are initially deep and narrow on the upper flanks of the composite cones and are filled bank-to-bank with lapilli-dominated debris flow deposits. These units spill out into larger channel systems forming debris aprons of thousands of overlapping and anastomosing long, narrow lobes of poorly sorted lapilli-dominated deposits. These deposits are typically remobilised by hyperconcentrated flows, debris-rich stream flows and rare debris flows that pass down increasingly shallower and broader box-shaped valleys. Lenses and lags of fines and primary fall deposits occur interbedded between the dominantly tabular hyperconcentrated flow deposits of these reaches. Aeolian sedimentation forms elongated sand dunes flanking the western rim of the ash-plain. Outside the caldera, initially steep-sided immature box-canyons are formed again, conveying dominantly hyperconcentrated flow deposits. These gradually pass into broad channels on lesser gradients in coastal areas and terminate at the coast in the form of prograding fans of ash-dominated deposits. The extra-caldera deposits are typically better sorted and contain other bedding features characteristic of more dilute fluvial flows and transitional hyperconcentrated flows. These outer flank volcaniclastics fill valleys to modify restricted portions of the dominantly constructional landscape (lava flows, and satellite cones) of Ambrym. Apparent maturity of the volcanic system has resulted in the subsidence of the present summit caldera at a similar rate to its infill by volcaniclastic deposits.

  16. Phylogeography of the prehensile-tailed skink Corucia zebrata on the Solomon Archipelago.

    PubMed

    Hagen, Ingerid J; Donnellan, Stephen C; Bull, C Michael

    2012-06-01

    The biogeography of islands is often strongly influenced by prior geological events. Corucia zebrata (Squamata: Scincidae) is endemic to the geologically complex Solomon Archipelago in Northern Melanesia. We examined the level of divergence for different island populations of C. zebrata and discussed these patterns in light of Pleistocene land bridges, island isolation, and island age. Corucia zebrata was sampled from 14 locations across the Solomon Archipelago and sequenced at two mitochondrial genes (ND2 and ND4; 1697 bp in total) and four nuclear loci (rhodopsin, an unknown intron, AKAP9, and PTPN12). Measures of genetic divergence, analyses of genetic variation, and Bayesian phylogenetic inference were used and the data assessed in light of geological information. Populations of C. zebrata on separate islands were found to be genetically different from each other, with reciprocal monophyly on mitochondrial DNA. Populations on islands previously connected by Pleistocene land bridges were marginally less divergent from each other than from populations on other nearby but isolated islands. There are indications that C. zebrata has radiated across the eastern islands of the archipelago within the last 1-4 million years. Nuclear loci were not sufficiently informative to yield further information about the phylogeography of C. zebrata on the Solomon Archipelago. Analyses of the mitochondrial data suggest that dispersal between islands has been very limited and that there are barriers to gene flow within the major islands. Islands that have been isolated during the Pleistocene glacial cycles are somewhat divergent in their mitochondrial genotypes, however, isolation by distance (IBD) and recent colonization of isolated but geologically younger islands appear to have had stronger effects on the phylogeography of C. zebrata than the Pleistocene glacial cycles. This contrasts with patterns reported for avian taxa, and highlights the fact that biogeographic regions for island species cannot be directly extrapolated among taxa of differing dispersal ability. PMID:22833796

  17. Multiplets and Detection of Seismic Velocity Changes During the 1998-99 Seismic Series at Deception Island Volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Carmona, E.; Martini, F.; Ibanez, J. M.; Bean, C. J.

    2007-12-01

    During the 1998-1999 Antarctic summer, the pattern of seismicity at Deception Island Volcano changed significantly with respect to previous years. This was characterized by the occurrence of an intense swarm of local earthquakes. More than 2000 local earthquakes were recorded in the period January-February 1999. The average moment magnitude was around 0.5, with the exception of two earthquakes of magnitude 2.3 and 3.4; array analysis was used to establish the hypocentral distribution of the earthquakes. A regional origin of the seismicity, or direct involvement of magmatic fluids, was demonstrated to be unlikely. Most earthquakes in the series were found to be related to small (<0.4 bar) stress changes on small faults which can be explained by lubrication by pressurized fluids (Ibanez et al. 2003). The presence of fluids in the source area could explain the fracturing process and is supported by the observation of hybrid events in the same source region. The study of the spatial distribution of the first motion of the P waves suggests that different source mechanisms acted in a very small volume, and often at the same time. Many distinct families of events with very similar waveforms were identified. When recorded at the same station, the similarity of repeating earthquakes indicates that source and wavepath are the same, and therefore any observed difference in waveforms is related to a change in the medium. Employing Coda Wave Interferometry (Snieder et al., 2002), the families of events identified in the series show a drop in the velocity over a short time period around the two events with bigger magnitudes. These variations may be related to cracking and/or fluid influx. After the seismic crisis, a change in the composition of the fumarolic gases was observed with the appearance of sulfur deposits around the fumaroles, and a clear uplift and inflation of a few centimeters was detected (Garcia et al., 2001). The seismic characteristics and the spatial and temporal behavior of the series, associated with other geochemical, bathymetric and geodetic observations, favor the hypothesis that the seismic series was caused by the stress generated by uplift of the source area due to magmatic injection in depth (Ibanez et al., 2003). The correlation between the observed velocity variations, and their timing with seismological, geochemical and geodetical evidence, supports the influx hypothesis as a causative mechanism.

  18. The tectonically controlled emplacement of a vertically sheeted gabbro-pyroxenite intrusion: Feeder-zone of an ocean-island volcano (Fuerteventura, Canary Islands)

    NASA Astrophysics Data System (ADS)

    Allibon, J.; Bussy, F.; Lewin, É.; Darbellay, B.

    2011-03-01

    The Miocene PX1 gabbro-pyroxenite pluton, Fuerteventura, Canary Islands, is a 3.5 × 5.5 km shallow-level intrusion (0.15-0.2 GPa and 1100-1120 °C), interpreted as the feeder-zone to an ocean-island volcano. It displays a vertical magmatic banding expressed in five 50 to 100 metre-wide NNE-SSW trending alkaline gabbro sequences alternating with pyroxenites. This emplacement geometry was controlled by brittle to ductile shear zones, generated by a regional E-W extensional tectonic setting that affected Fuerteventura during the Miocene. At a smaller scale, the PX1 gabbro and pyroxenite bands consist of metre-thick differentiation units, which suggest emplacement by periodic injection of magma pulses as vertical dykes that amalgamated, similarly to a sub-volcanic sheeted dyke complex. Individual dykes underwent internal differentiation following a solidification front parallel to the dyke edges. This solidification front may have been favoured by a significant lateral/horizontal thermal gradient, expressed by the vertical banding in the gabbros, the fractionation asymmetry within individual dykes and the migmatisation of the wall rocks. Pyroxenitic layers result from the fractionation and accumulation of clinopyroxene ± olivine ± plagioclase crystals from a mildly alkaline basaltic liquid. They are interpreted as truncated differentiation sequences, from which residual melts were extracted at various stages of their chemical evolution by subsequent dyke intrusions, either next to or within the crystallising unit. Compaction and squeezing of the crystal mush is ascribed to the incoming and inflating magma pulses. The expelled interstitial liquid was likely collected and erupted along with the magma flowing through the newly injected dykes. Clinopyroxene mineral orientation - as evidenced by EBSD and micro X-ray tomography investigations - displays a marked pure-shear component, supporting the interpretation of the role of compaction in the generation of the pyroxenites. Conversely, gabbro sequences underwent minor melt extraction and are believed to represent crystallised coalesced magma batches emplaced at lower rates at the end of eruptive cycles. Clinopyroxene orientations in gabbros record a simple shear component suggesting syn-magmatic deformation parallel to observed NNE-SSW trending shear zones induced by the regional tensional stress field. This emplacement model implies a crystallisation time of 1 to 5 years for individual dykes, consistent with PX1 emplacement over less than 0.5 My. A minimum amount of approximately 150 km 3 of magma is needed to generate the pluton, part of it having been erupted through the Central Volcanic Centre of Fuerteventura. If the regional extensional tectonic regime controls the PX1 feeder-zone initiation and overall geometry, rates and volumes of magma depend on other, source-related factors. High injection rates are likely to induce intrusion growth rates larger than could be accommodated by the regional extension. In this case, dyke intrusion by propagation of a weak tip, combined with the inability of magma to circulate through previously emplaced and crystallised dykes could result in an increase of non-lithostatic pressure on previously emplaced mushy dyke walls; thus generating strong pure-shear compaction within the pluton feeder-zone and interstitial melt expulsion. These compaction-dominated processes are recorded by the cumulitic pyroxenite bands.

  19. Response of the shallow aquifer of the volcano-hydrothermal system during the recent crises at Vulcano Island (Aeolian Archipelago, Italy)

    NASA Astrophysics Data System (ADS)

    Capasso, Giorgio; Federico, Cinzia; Madonia, Paolo; Paonita, Antonio

    2014-03-01

    The shallow thermal aquifer at Vulcano Island is strongly affected by deep volcanic fluids. The most significant variations were observed during the 1989-1996 crisis due to a large input of steam and acidic gases from depth. Besides chemical variations related to the input of deep fluids, the record of the water-table elevation at monitored wells has provided remarkable insights into the pressure conditions of the volcano-hydrothermal system. After the pressure drop due to the extensive vaporization of the hydrothermal aquifer, occurred after 1993, the volcano-hydrothermal system has been re-pressurized since 2001, probably because of the contribution of volatiles from the hydrothermal-magmatic source. The increase in fluid pressure may have caused reopening of fractures (which had self-seated during the previous period of cooling) and the onset of a phase of higher vapor output in the fumarole field later in 2004. The fracture opening would have promoted further vapor separation from the deep fluid reservoir (hypothesized at 0.5-1.5 km depth) and finally the drainage of S-rich fluids into the shallow thermal aquifer (found out at few tens of meters of depth). The monitoring of both the water chemistry and the water-table elevation provides insights into the eventual pressurization of the volcano-hydrothermal system that precedes the fracture opening and the extensive drainage of deep fluids. The findings of this study could represent crucial information about the stability of the volcano edifice, and lead to reliable techniques for determining the risk of or even predicting phreatic explosions.

  20. 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.

  1. 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.

  2. Insights from geophysical monitoring into the volcano structure and magma supply systems at three very different oceanic islands in the Cape Verde archipelago

    NASA Astrophysics Data System (ADS)

    Faria, B. V.; Day, S.; Fonseca, J. F.

    2013-12-01

    Three oceanic volcano islands in the west of the Cape Verde archipelago are considered to have the highest levels of volcanic hazard in the archipelago: Fogo, Brava, and Santo Antao. Fogo has had frequent mainly effusive eruptions in historic time, the most recent in 1995, whilst Brava and Santo Antao have ongoing geothermal activity and felt earthquakes, and have experienced geologically recent violent explosive eruptions. Therefore, these three islands have been the focus of recent efforts to set up seismic networks to monitor their activity. Here we present the first results from these networks, and propose interpretations of the monitored seismic activity in terms of subsurface volcano structures, near-surface intrusive activity and seasonal controls on geothermal activity. In Fogo, most recorded seismic events are hydrothermal events. These show a strong seasonal variation, increasing during the summer rain season and decreasing afterwards. Rare volcano-tectonic (VT) events (0.1island due to the 1995 eruption. Brava experiences frequent swarms of VT events. These are located mostly offshore, with a small proportion of on-shore events. The positions of offshore events are strongly correlated with seamounts and hence are interpreted as due to submarine volcanic processes. Onshore events (0.7island that has been indicated by previous geological studies, and may be due to inflation of a magma reservoir in the edifice. S. Anto is characterized by frequent seismic swarms composed of VT earthquakes (0.1volcanoes on Santo Antao, which are most probably also the sources of the associated MF events and harmonic tremor as well. These onshore swarms likely record dike intrusions into the volcanic rift zones. In conclusion, we note that each island has its own distinctive pattern of seismic activity, perhaps reflecting its different stage of evolution. Full understanding of the seismic activity and how it can be interpreted in mechanistic terms, as a basis for future volcanic hazard models and eruption forecasts, will therefore require more detailed geological and geophysical investigations of each island, with different priorities in each case.

  3. 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.

  4. Adventive hydrothermal circulation on Stromboli volcano (Aeolian Islands, Italy) revealed by geophysical and geochemical approaches: Implications for general fluid flow models on volcanoes

    NASA Astrophysics Data System (ADS)

    Finizola, A.; Ricci, T.; Deiana, R.; Cabusson, S. Barde; Rossi, M.; Praticelli, N.; Giocoli, A.; Romano, G.; Delcher, E.; Suski, B.; Revil, A.; Menny, P.; Di Gangi, F.; Letort, J.; Peltier, A.; Villasante-Marcos, V.; Douillet, G.; Avard, G.; Lelli, M.

    2010-09-01

    On March 15th 2007 a paroxysmal explosion occurred at the Stromboli volcano. This event generated a large amount of products, mostly lithic blocks, some of which impacted the ground as far as down to 200 m a.s.l., about 1.5 km far away from the active vents. Two days after the explosion, a new vapour emission was discovered on the north-eastern flank of the volcanic edifice, at 560 m a.s.l., just above the area called "Nel Cannestr". This new vapour emission was due to a block impact. In order to investigate the block impact area to understand the appearance of the vapour emission, we conducted on May 2008 a multidisciplinary study involving Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), Self-Potential (SP), CO 2 soil diffuse degassing and soil temperature surveys. This complementary data set revealed the presence of an anomalous conductive body, probably related to a shallow hydrothermal level, at about 10-15 m depth, more or less parallel to the topography. It is the first time that such a hydrothermal fluid flow, with a temperature close to the water boiling point (76 C) has been evidenced at Stromboli at this low elevation on the flank of the edifice. The ERT results suggest a possible link between (1) the main central hydrothermal system of Stromboli, located just above the plumbing system feeding the active vents, with a maximum of subsurface soil temperature close to 90 C and limited by the NeoStromboli summit crater boundary and (2) the investigated area of Nel Cannestr, at ~ 500 m a.s.l., a buried eruptive fissure active 9 ka ago. In parallel, SP and CO 2 soil diffuse degassing measurements suggest in this sector at slightly lower elevation from the block impact crater a magmatic and hydrothermal fluid rising system along the N41 regional fault. A complementary ERT profile, on May 2009, carried out from the NeoStromboli crater boundary down to the block impact crater displayed a flank fluid flow apparently connected to a deeper system. The concept of shallow hydrothermal level have been compared to similar ERT results recently obtained on Mount Etna and La Fossa cone of Vulcano. This information needs to be taken into account in general fluid flow models on volcanoes. In particular, peripheral thermal waters (as those bordering the north-eastern coast of Stromboli) could be contaminated by hydrothermal and magmatic fluids coming from regional faults but also from the summit.

  5. Solomon V. Shereshevsky: the great Russian mnemonist.

    PubMed

    Mecacci, Luciano

    2013-09-01

    A biographical sketch is given of Solomon V. Shereshevsky, a man gifted with exceptional memory skills who became famous after the publication of Aleksandr R. Luria's book The Mind of a Mnemonist, in 1968. PMID:23871306

  6. Numerical modeling of tsunami waves generated by the flank collapse of the Cumbre Vieja Volcano (La Palma, Canary Islands): Tsunami source and near field effects

    NASA Astrophysics Data System (ADS)

    Abadie, S. M.; Harris, J. C.; Grilli, S. T.; Fabre, R.

    2012-05-01

    In this work, we study waves generated by the potential collapse of the west flank of the Cumbre Vieja Volcano (CVV; La Palma, Canary Island, Spain) through numerical simulations performed in two stages: (i) the initial slide motion and resulting free surface elevation are first calculated using a 3D Navier-Stokes model; (ii) generated waves are then input into a 2D (horizontal) Boussinesq model to further simulate propagation to the nearby islands. Unlike in earlier work on CVV, besides a similar extreme slide volume scenario of 450 km3, in our simulations: (i) we consider several slide scenarios featuring different volumes (i.e., 20, 40, 80 km3), which partly result from a geotechnical slope stability analysis; (ii) we use a more accurate bathymetry; and (iii) an incompressible version of a multiple-fluid/material Navier-Stokes model. We find wave trains for each scenario share common features in terms of wave directivity, frequency, and time evolution, but maximum elevations near CVV significantly differ, ranging from 600 to 1200 m (for increasing slide volume). Additionally, our computations show that significant energy transfer from slide to waves only lasts for a short duration (order 200 s), which justifies concentrating our best modeling efforts on the early slide motion phase. The anticipated consequences of such wave trains on La Palma and other Canary Islands are assessed in detail in the paper.

  7. Control Circuit For Reed-Solomon Encoder

    NASA Technical Reports Server (NTRS)

    Ross, Douglas

    1992-01-01

    Control circuit designed for use with commercially available AHA4610 Reed-Solomon encoder. Needed to select depth of interleaving and to synchronize input and output blocks of data and parity bits with suitable clock signals. Circuit provides synchronizing and control signals for Reed-Solomon encoder. Encoder can operate with asynchronous input and output data streams at rates up to 80 Mb/s. Interleaving depth selectable, and accommodation to input data rate automatic.

  8. Spacecraft Reed-Solomon downlink module

    NASA Technical Reports Server (NTRS)

    Luong, Huy H. (Inventor); Donaldson, James A. (Inventor); Wood, Steven H. (Inventor)

    1998-01-01

    Apparatus and method for providing downlink frames to be transmitted from a spacecraft to a ground station. Each downlink frame includes a synchronization pattern and a transfer frame. The apparatus may comprise a monolithic Reed-Solomon downlink (RSDL) encoding chip coupled to data buffers for storing transfer frames. The RSKL chip includes a timing device, a bus interface, a timing and control unit, a synchronization pattern unit, and a Reed-Solomon encoding unit, and a bus arbiter.

  9. Amplitude Comparison of Teleseismic P-Wave Phases from the Japan Subduction Zone and the South Sandwich Islands recorded at Uturuncu Volcano, Bolivia

    NASA Astrophysics Data System (ADS)

    Farrell, A. K.; McNutt, S. R.; West, M. E.

    2012-12-01

    Uturuncu volcano (22 15' S, 67 12'W) has been shown to be inflating at a rate of 1-1.5 cm per year by a satellite geodetic survey from May 1996-present. This inflation is centered just southwest of the volcano's summit and at a depth of 15-17 km. This may be caused by the injection of magma into the system. Seismic studies performed as part of the multi-university PLUTONS project can help constrain the location and nature of this inflation. By looking at how teleseismic peak-to-peak waveform amplitudes (velocities in nm/s) vary across the network, we can begin to pinpoint the size and location of attenuating zones beneath the edifice. Analysis of 5 P-wave phases from 4 earthquakes with origins in the Japan subduction zone (NW of the network, ~155 distant) shows a consistent 'shadow zone' of decreased amplitudes in a 13.6 by 33.3 km zone to the SE of the summit. Observations from two teleseismic events originating in the South Sandwich Islands (~45 distant) show similar effects although the geometry differs with respect to individual stations. We expect this trend to hold true for events originating to the NE and SW of the volcano, which would indicate a zone of decreased amplitude in the same region SE of the summit. The attenuation of P-waves that would otherwise be of uniform amplitude could be the result of some ray paths traveling through a shallow, low-velocity and highly attenuating zone of either magma/mush, highly fractured rock, or some other cause. This attenuating zone may be located at or near the center of the inflation zone, and physical processes associated with it could well be closely related to the observed inflation.

  10. 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 ...

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Guffanti, Marianne; Ewert, John W.; Gallina, Gregory M.; Bluth, Gregg J. S.; Swanson, Grace L.

    2005-08-01

    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 SO 2 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.

  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

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Sunarta, N.

    1994-04-01

    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 characteristics are closely correlated to the distribution of the volcanic stratigraphy derived from the Batur volcanic activities with the eruption about 23,700 years ago. On the basis of these data, the hydrogeological situation of the slope are presented schematically and groundwater flow regimes on the slope, such as recharge and discharge areas, are also classified according to the hydrogeological information. These classifications of groundwater flow regimes are useful to consider the occurrence of hydrological phenomena such as springs and paddy field distributions observed on the slope.

  14. Exploring SARAL/Altika data in the Solomon Sea

    NASA Astrophysics Data System (ADS)

    Djath, Bughsin; Ganachaud, Alexandre; Gourdeau, Lionel; Verron, Jacques

    2015-04-01

    In the South West Pacific, the Solomon Sea is a key region in the oceanic climate circuit that connects the equator to the subtropics through the LLWBCs (Low Latitude Western Boundary Currents). In their pathway toward the equator, their changes in strength or water masses properties could influence ENSO low-frequence modulation. Besides, it exhibits the highest variability of the southwest Pacific. Recent studies (Gourdeau et al., 2014; Hristina et al., 2014) have highlighted the specific eddy activity in this region: eddy generation/propagation and mechanism at the mesoscales. However, this region is poorly documented because of the lack of observation data. Only space observation and numerical model could give a synoptic monitoring of this region. Indeed, SARAL/Altika is providing improved high resolution data for studying mesoscale processes in the ocean. The goal of this study is to monitor mesoscale variability, the western boundary currents and pathways toward the equator. A dual approach, based both on SARAL/Altika along track data and high resolution modeling has then been chosen for these purpose. In this study, to analyze altimetric data, we use a specific median filter as the bathymetry of the Solomon Sea is complex (due to numerous islands and straits). The reprocessing data permits to eliminate erroneous data and provide a good quality dataset. It shows a high variability in the Solomon Sea. In order to explore SARAL/Altika temporal observability of mesoscale signal, a high resolution numerical model (1/36) is used. The model is two-way embedded in a 1/12 regional model which is itself one-way embedded in the DRAKKAR 1/12 global model. The NEMO code is used as well as the AGRIF software for model nestings

  15. 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.

  16. Influence of an ocean on the propagation of magmas within an oceanic basaltic shield volcano

    NASA Astrophysics Data System (ADS)

    Le Corvec, N.; McGovern, P. J., Jr.

    2014-12-01

    Basaltic shield volcanoes are a common feature on Earth and mostly occur within oceans, forming volcanic islands (e.g. Hawaii (USA), Galapagos (Ecuador), and recently Niijima (Japan)). As the volcano grows it will reach and emerge from the water surface and continue to grow above it. The deformation affecting the volcanic edifice may be influenced by the presence of the water level. We investigate how the presence of an ocean affects the state of stress within a volcanic edifice and thus magma propagation and fault formation. Using COMSOL Multiphysics, axisymmetric elastic models of a volcanic edifice overlying an elastic lithosphere were created. The volcanic edifice (height of ~6000 m and radius of ~ 60 km) was built either instantaneously or iteratively by adding new layers of equivalent volume on top of each other. In the later process, the resulting stress and geometry from the one step is transferred to the next as initial conditions. Thus each new layer overlies a deformed and stressed model. The water load was modeled with a boundary condition at the surface of the model. In the case of an instantaneous volcano different water level were studied, for an iteratively growing volcano the water level was set up to 4000 m. We compared the deformation of the volcanic edifice and lithosphere and the stress orientation and magnitude in half-space and flexural models with the presence or not of an ocean. The preliminary results show 1- major differences in the resulting state of stress between an instantaneous and an iteratively built volcanic edifice, similar to the results of [Galgana et al., 2011] and [McGovern and Solomon, 1993], respectively; 2- the presence of an ocean decreases the amount of flexural response, which decreases the magnitude of differential stress within the models; and 3- stress orientation within the volcano and lithosphere in also influence of an ocean. Those results provide new insights on the state of stress and deformation of oceanic basaltic volcanic edifices. Galgana, G. A., P. J. McGovern, and E. B. Grosfils (2011), J. Geophys. Res., 116(E3), E03009. McGovern, P. J., and S. C. Solomon (1993), Journal of Geophysical Research: Planets, 98(E12), 23553-23579.

  17. Reawakening of the Teide volcano (Tenerife island, Spain): Monitoring the activity through the analysis of continuous seismic and GPS data.

    NASA Astrophysics Data System (ADS)

    Ortiz, R.; Vila, J.; Garca, A.; Trraga, M.; Carniel, R.; Marrero, J. M.; Carmona, J.; Fernndez-Ros, A.; Berrocoso, M.

    2009-04-01

    The reawakening of the Teide volcano in 2004 caused the installation of several seismic and GPS stations, operating in continuous mode. This allowed the application of different techniques of time sequence data analysis. The results of the analysis of the background seismic noise, deformation model and b parameter of located seismic events show evidences of a magmatic process in course, probably related to the central volcanic system of Tenerife. Other obtained results not only allow the occurrence of tectonic events (volcanotectonic??) forecasting, but also the establishment of a clear influence in the variation of the background noise characteristics.

  18. Mount St. Helens and Kilauea volcanoes

    SciTech Connect

    Barrat, J. )

    1989-01-01

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

  19. The growth of Ritter Island volcano, Papua New Guinea, and the lateral collapse landslide and tsunami of 1888: new insights from eyewitness accounts

    NASA Astrophysics Data System (ADS)

    Ray, Melanie Jane; Day, Simon; Downes, Hilary

    2014-05-01

    We present a case study of the 1888 edifice lateral collapse landslide and tsunami event at Ritter Island volcano, using a more complete set of primary and secondary eyewitness accounts than has been used in previous studies. The collapse, early in the morning of March 13th, 1888, removed most of the island and its western submarine flank down to the base of the edifice some 900 m below sea level. The resulting tsunami is believed to have eradicated entire coastal communities on the surrounding islands and was recorded by German colonists in several locations around the Bismarck Sea and on adjacent coasts. Our analysis, based in particular upon new and complete translation of the German accounts, considers the evolution of the island over the previous two centuries and the events of March 1888, with the aim of clarifying the constraints that exist upon the cause, kinematics and mechanisms of the lateral collapse. Our analysis indicates that the pre-collapse Ritter edifice produced frequent strombolian eruptions and steam emissions, building an approximately 1700 m wide, notably steep-sided edifice with a N-S elongated oval shape in plan, by the late 1800s. Most activity was concentrated at a group of summit craters some 800 m above sea level, possibly also in a north-south line, with lesser flank fissure activity. The accounts of the tsunami indicate that the 1888 collapse involved a single large-scale catastrophic landslide, but descriptions of the island in the following days indicate a period in which there were many small landslides from the newly formed and unstable collapse scar. There is no evidence for a sequence of large landslides during this event and there is no clear evidence for a coincident or causal magmatic explosive eruption. One report suggests that there was activity (perhaps phreatic or phreatomagmatic explosions?) prior to the collapse that lead some of the resident local communities to seek higher ground, but evidence for precursory flank movements or changes in eruptive style have not been found in the historical accounts.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Shield volcanoes are a common feature of basaltic volcanism. Their volcanic activity is often confined to a summit crater area and rift systems, both characterized by constructive (scoria and cinder cones; lava flows) and destructive (pit craters; caldera collapse) phenomena. Piton de la Fournaise (PdF) shield volcano (La Réunion Island, Indian Ocean) is an ideal place to study these differences in eruptive behaviour. Besides the frequent eruptions in the central Enclos Fouqué caldera, hundreds of eruptive vents opened along three main rift zones cutting the edifice during the last 50 kyrs. Two short rift zones are characterized by weak seismicity and lateral magma transport at shallow depth (above sea level). Here we focus on the third and largest rift zone (15km wide, 20 km long), which extends in a north-westerly direction between PdF and nearby Piton des Neiges volcanic complex. It is typified by deep seismicity (up to 30 km), emitting mostly primitive magmas, testifying of high fluid pressures (up to 5 kbar) and large-volume eruptions. We present new field data (including stratigraphic logs, a geological map of the area, C-14 dating and geochemical analyses of the eruption products) on one of the youngest (~6kyrs) and largest lava field (Trous Blancs eruption). It extends for 24km from a height of 1800 m asl, passing Le Tampon and Saint Pierre cities, until reaching the coast. The source area of this huge lava flow has been identified in an alignment of four previously unidentified pit craters. The eruption initiated with intense fountaining activity, producing a m-thick bed of loose black scoria, which becomes densely welded in its upper part; followed by an alternation of volume rich lava effusions and strombolian activity, resulting in the emplacement of meter-thick, massive units of olivine-basalt alternating with coarse scoria beds in the proximal area. Activity ended with the emplacement of a dm-thick bed of glassy, dense scoria and a stratified lithic breccia, marking the pit crater foundering. Interestingly, this final stage compares well with the formation of pit craters on Kilauea volcano, Hawaii. Reoccurring of similar activity on the NW rift represents a major source of risk, for this now densely populated region (more than 150,000 people living in the affected area).

  3. 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...

  4. Schematic driven layout of Reed Solomon encoders

    NASA Technical Reports Server (NTRS)

    Arave, Kari; Canaris, John; Miles, Lowell; Whitaker, Sterling

    1992-01-01

    Two Reed Solomon error correcting encoders are presented. Schematic driven layout tools were used to create the encoder layouts. Special consideration had to be given to the architecture and logic to provide scalability of the encoder designs. Knowledge gained from these projects was used to create a more flexible schematic driven layout system.

  5. 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.

  6. Species-area relation for birds of the Solomon Archipelago.

    PubMed

    Diamond, J M; Mayr, E

    1976-01-01

    Accurate values of number of breeding bird species have been obtained for 50 islands of the Solomon Archipelago. From information about species altitudinal distributions on each island, the values are apportioned into number of montane species (S(mt)) and of species present at sea-level (S(low)). S(low) increases linearly with the logarithm of island area A over a million-fold range of areas (correlation coefficient 0.99) and with a comparatively low slope, while the log S-log A relation is markedly curved. With increasing isolation of an archipelago, the species-area relation decreases in slope and may shift in form from a power function to an exponential. Comparison of Pacific archipelagoes at different distances from the colonization source of New Guinea shows that the decrease in slope is due to increasing intra-archipelago immigration rates, arising from overrepresentation of the most vagile inter-archipelago immigrants in more distant archipelagoes. When colonists are sorted into sets correlated with their dispersal abilities, the slope of the species-area relation for the most vagile set is close to zero, but for the least vagile set is close to the value predicted by Preston for "isolated universes." PMID:16592301

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  8. Variability in Solomon Sea circulation derived from altimeter sea level data

    NASA Astrophysics Data System (ADS)

    Melet, Anglique; Gourdeau, Lionel; Verron, Jacques

    2010-08-01

    The Solomon Sea is a key region in the Pacific Ocean where equatorial and subtropical circulations are connected. The region exhibits the highest levels in sea level variability in the entire south tropical Pacific Ocean. Altimeter data was utilized to explore sea level and western boundary currents in this poorly understood portion of the ocean. Since the geography of the region is extremely intricate, with numerous islands and complex bathymetry, specifically reprocessed along-track data in addition to standard gridded data were utilized in this study. Sea level anomalies (SLA) in the Solomon Sea principally evolve at seasonal and interannual time scales. The annual cycle is phased by Rossby waves arriving in the Solomon Strait, whereas the interannual signature corresponds to the basin-scale ENSO mode. The highest SLA variability are concentrated in the eastern Solomon Sea, particularly at the mouth of the Solomon Strait, where they are associated with a high eddy kinetic energy signal that was particularly active during the phase transition during the 1997-1998 ENSO event. Track data appear especially helpful for documenting the fine structure of surface coastal currents. The annual variability of the boundary currents that emerged from altimetry compared quite well with the variability seen at the thermocline level, as based on numerical simulations. At interannual time scales, western boundary current transport anomalies counterbalance changes in western equatorial Pacific warm water volume, confirming the phasing of South Pacific western boundary currents to ENSO. Altimetry appears to be a valuable source of information for variability in low latitude western boundary currents and their associated transport in the South Pacific.

  9. 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

  10. 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

  11. Investigation of the Volcano-tectonic dynamics of Vulcano Island by long-term (40 years) geophysical data

    NASA Astrophysics Data System (ADS)

    Bonforte, Alessandro; Alparone, Salvatore; Gambino, Salvatore; Guglielmino, Francesco; Obrizzo, Francesco; Velardita, Rosanna

    2015-04-01

    Vulcano island is a composite volcanic edifice located in the south-central sector of the Aeolian Archipelago (Tyrrhenian Sea, Italy). It is the southernmost tip of the southern branch of the Y-shaped archipelago; in particular, it is part of the bigger Lipari-Vulcano volcanic complex that comprises the two southernmost islands of the archipelago. This branch of the archipelago is NNW-SSE oriented and represent the off-shore prolongation of the Tindari-Letojanni tectonic lineament in the NE Sicily, splitting the Appennine chain on the west, from the Calabrian arc on the East. N-S compression seems to affect the western side of this NNW-SSE lineament, while extension affects the eastern one, with active volcanism and a NW dipping Benioff plane. Historic activity at Vulcano has been characterized by frequent transitions from phereatomagmatic to minor magmatic activity. The last eruption in 1888-90 was characterized by energetic explosive pulses and defines the so-called "vulcanian" type of activity. Since then, volcanic activity has taken the form of fumarolic emanations of variable intensity and temperature, mainly concentrated at "La Fossa" crater, with maximum temperatures ranging between 200° and 300° C; temperature increases and changes in the gas chemistry, were often observed. The most recent episode began in the 80's when fumarole temperature progressively increased to 690°C in May 1993. Vulcano is active and this favoured monitoring and research studies, in particular focussed on the most recent structures. In the frame of DPC-INGV "V3" project, we investigate the dynamics of the island through ca. 40 years of ground deformation and seismicity data collected by the discrete and continuous INGV monitoring networks. We considered levelling, GPS, EDM, seismic and tilt data. EDM and levelling measurements began in the middle 1970s and since the late 1990s the same EDM network has been surveyed by GPS. By combining and comparing geodetic data and seismicity we are able to distinguish three different scales of phenomena: the first one seems to be linked to the regional tectonics, with a general transpressive kinematics; the second one affects the northern half of the island and could be related to the caldera dynamics; the third one affects only the cone of La Fossa. Regional tectonic stress seems to play an important role in the transition of the volcanic system from a phase of stability to a phase of unrest, inducing the heating and the expansion of shallow hydrothermal fluids. Current local ground deformation at Vulcano may be linked to the geothermal system rather than magmatic sources.

  12. Erupting Volcano Mount Etna

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  13. Origin of anorthite and olivine megacrysts in island-arc tholeiites: petrological study of 1940 and 1962 ejecta from Miyake-jima volcano, Izu-Mariana arc

    NASA Astrophysics Data System (ADS)

    Amma-Miyasaka, Mizuho; Nakagawa, Mitsuhiro

    2002-10-01

    Although aphyric tholeiites were discharged from nearly the same fissures during 1940 and 1962 eruptions of Miyake-jima volcano, some of the 1940 rocks are characterized by the presence of anorthite (to 3 cm) and olivine (to 4 mm) megacrysts. We focus on the assemblage and composition of crystal-clots to discuss magmatic processes, because minerals in the same type of clots must have crystallized at the same time. Three types of clots are identified, megacryst (M), basaltic (B; 1190-1175C) and andesitic (A; 1150-1080C). The M-type crystal-clots are characterized by anorthite (An 87-96) and olivine (Fo 78-86) megacrysts. Major mafic minerals of the B-type and A-type crystal-clots are olivine-clinopyroxene without magnetite, and pyroxenes with magnetite, respectively. The 1940 megacryst-bearing rocks contain all the three types of clots, whereas 1940 megacryst-free rocks contain only A-type and B-type. However, megacrysts and M-type clots show petrographic features such as kink-bands of olivine, spherical olivines in anorthite, and wide homogeneous cores of anorthite, suggesting that these minerals may not be comagmatic phenocrysts but xenocrysts. Chemical compositions and crystal size distribution plots of these crystals are identical to those of plutonic xenoliths erupted from one of the 1940 fissure. Thus, we concluded that megacrysts and M-type clots are xenocrysts derived from the same sources as plutonic xenoliths. We consider that the magma plumbing system of the 1940 eruption consists of a deeper basaltic magma storage system and a shallower andesitic one. The plutonic body might be located under the northeastern part of the volcano between two magma storage systems. The basaltic magma captured plutonic xenoliths, and then mixed with the andesitic magma during the 1940 eruption. Whether erupted rocks contain xenocrysts or not must depend on the spatial relationship between ascending basaltic dykes and location of the deep-seated plutonic body. On the other hand, the 1962 ejecta contain only A-type crystal-clots, indicating that only shallower andesitic magma was discharged. Although anorthite megacrysts are often recognized in island-arc tholeiites, calcic plagioclase could crystallize not from nearly dry tholeiites but from H 2O-saturated conditions. This could be achieved by closed system differentiation and/or addition of H 2O from the crust, such as plutonic conditions.

  14. Hawaiian Island Archipelago

    NASA Technical Reports Server (NTRS)

    1988-01-01

    In this view of the entire Hawaiian Island Archipelago (21.0N, 157.0W), the islands perturb the prevailing northeastewrly winds producing extensive cloud wakes in the lee of the islands. The atmospheric haze within the wake is a result of the near continuous eruptions of Kilauea volcano on the southeast coast of the big island of Hawaii.

  15. Under the volcano: phylogeography and evolution of the cave-dwelling Palmorchestia hypogaea (Amphipoda, Crustacea) at La Palma (Canary Islands)

    PubMed Central

    Villacorta, Carlos; Jaume, Dami; Orom, Pedro; Juan, Carlos

    2008-01-01

    Background The amphipod crustacean Palmorchestia hypogaea occurs only in La Palma (Canary Islands) and is one of the few terrestrial amphipods in the world that have adapted to a strictly troglobitic life in volcanic cave habitats. A surface-dwelling closely related species (Palmorchestia epigaea) lives in the humid laurel forest on the same island. Previous studies have suggested that an ancestral littoral Orchestia species colonized the humid forests of La Palma and that subsequent drought episodes in the Canaries reduced the distribution of P. epigaea favouring the colonization of lava tubes through an adaptive shift. This was followed by dispersal via the hypogean crevicular system. Results P. hypogaea and P. epigaea did not form reciprocally monophyletic mitochondrial DNA clades. They showed geographically highly structured and genetically divergent populations with current gene flow limited to geographically close surface locations. Coalescence times using Bayesian estimations assuming a non-correlated relaxed clock with a normal prior distribution of the age of La Palma, together with the lack of association of habitat type with ancestral and recent haplotypes, suggest that their adaptation to cave life is relatively ancient. Conclusion The data gathered here provide evidence for multiple invasions of the volcanic cave systems that have acted as refuges. A re-evaluation of the taxonomic status of the extant species of Palmorchestia is needed, as the division of the two species by habitat and ecology is unnatural. The information obtained here, and that from previous studies on hypogean fauna, shows the importance of factors such as the uncoupling of morphological and genetic evolution, the role of climatic change and regressive evolution as key processes in leading to subterranean biodiversity. PMID:18234125

  16. Quantitative analysis of seismic wave propagation anomalies in azimuth and apparent slowness at Deception Island volcano (Antarctica) using seismic arrays

    NASA Astrophysics Data System (ADS)

    Yeguas, A. Garca.; Almendros, J.; Abella, R.; Ibez, J. M.

    2011-02-01

    We analyse shot data recorded by eight seismic arrays during an active-source seismic experiment carried out at Deception Island (Antarctica) in 2005 January. For each source we estimate the apparent slowness and propagation azimuth of the first wave arrival. Since both source and receiver positions are accurately known, we are able to interpret the results in terms of the effect of the heterogeneities of the medium on wave propagation. The results show the presence of significant propagation anomalies. Nearby shots produce large apparent slowness values above 0.6 s km-1, while distant shots produce small values, down to about 0.15-0.20 s km-1. These values are different for each array, which shows the importance of the local structure under the receiver. The spatial distributions of apparent slowness are not radial as we would expect in a flat-layered medium. And again, these distributions are different for each array. The azimuth anomalies defined as the difference between the empirical estimates and the values expected in a 1-D model (i.e. the source-array directions) suggest ubiquitous wave front distortions. We have detected both positive and negative anomalies. For some shot-array geometries, azimuth anomalies are quite large with values up to 60. The distribution of the anomalies depends on the position of the array. Some of these features can be interpreted in terms of a shallow magma chamber and shallow rigid bodies imaged by high-resolution seismic tomography. However several details remain unexplained. Further work is required, including modelling of synthetic wavefields on realistic models of Deception Island and/or apparent slowness vector tomography.

  17. Modular VLSI Reed-Solomon Decoder

    NASA Technical Reports Server (NTRS)

    Hsu, In-Shek; Truong, Trieu-Kie

    1991-01-01

    Proposed Reed-Solomon decoder contains multiple very-large-scale integrated (VLSI) circuit chips of same type. Each chip contains sets of logic cells and subcells performing functions from all stages of decoding process. Full decoder assembled by concatenating chips, with selective utilization of cells in particular chips. Cost of development reduced by factor of 5. In addition, decoder programmable in field and switched between 8-bit and 10-bit symbol sizes.

  18. Systolic VLSI Reed-Solomon Decoder

    NASA Technical Reports Server (NTRS)

    Shao, H. M.; Truong, T. K.; Deutsch, L. J.; Yuen, J. H.

    1986-01-01

    Decoder for digital communications provides high-speed, pipelined ReedSolomon (RS) error-correction decoding of data streams. Principal new feature of proposed decoder is modification of Euclid greatest-common-divisor algorithm to avoid need for time-consuming computations of inverse of certain Galois-field quantities. Decoder architecture suitable for implementation on very-large-scale integrated (VLSI) chips with negative-channel metaloxide/silicon circuitry.

  19. Microsatellite and mitochondrial markers reveal strong gene flow barriers for Anopheles farauti in the Solomon Archipelago: implications for malaria vector control?

    PubMed Central

    Ambrose, Luke; Cooper, Robert D.; Russell, Tanya L.; Burkot, Thomas R.; Lobo, Neil F.; Collins, Frank H.; Hii, Jeffrey; Beebe, Nigel W.

    2014-01-01

    Anopheles farauti is the primary malaria vector throughout the coastal regions of the Southwest Pacific. A shift in peak biting time from late to early in the night occurred following widespread indoor residue spraying of dichlorodiphenyltrichloroethane (DDT) and has persisted in some island populations despite the intervention ending decades ago. We used mitochondrial cytochrome oxidase I (COI) sequence data and 12 newly developed microsatellite markers to assess the population genetic structure of this malaria vector in the Solomon Archipelago. With geographically distinct differences in peak A. farauti night biting time observed in the Solomon Archipelago, we tested the hypothesis that strong barriers to gene flow exist in this region. Significant and often large fixation index (FST) values were found between different island populations for the mitochondrial and nuclear markers, suggesting highly restricted gene flow between islands. Some discordance in the location and strength of genetic breaks was observed between the mitochondrial and microsatellite markers. Since early night biting A. farauti individuals occur naturally in all populations, the strong gene flow barriers that we have identified in the Solomon Archipelago lend weight to the hypothesis that the shifts in peak biting time from late to early night have appeared independently in these disconnected island populations. For this reason, we suggest that insecticide impregnated bed nets and indoor residue spraying are unlikely to be effective as control tools against A. farauti occurring elsewhere, and if used, will probably result in peak biting time behavioural shifts similar to that observed in the Solomon Islands. PMID:24440418

  20. Trace-shortened Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Mceliece, R. J.; Solomon, G.

    1994-01-01

    Reed-Solomon (RS) codes have been part of standard NASA telecommunications systems for many years. RS codes are character-oriented error-correcting codes, and their principal use in space applications has been as outer codes in concatenated coding systems. However, for a given character size, say m bits, RS codes are limited to a length of, at most, 2(exp m). It is known in theory that longer character-oriented codes would be superior to RS codes in concatenation applications, but until recently no practical class of 'long' character-oriented codes had been discovered. In 1992, however, Solomon discovered an extensive class of such codes, which are now called trace-shortened Reed-Solomon (TSRS) codes. In this article, we will continue the study of TSRS codes. Our main result is a formula for the dimension of any TSRS code, as a function of its error-correcting power. Using this formula, we will give several examples of TSRS codes, some of which look very promising as candidate outer codes in high-performance coded telecommunications systems.

  1. Distribution, 14C chronology, and paleomagnetism of latest Pleistocene and Holocene lava flows at Haleakala volcano, Island of Maui, Hawai'i: a revision of lava flow hazard zones

    USGS Publications Warehouse

    Sherrod, David R.; Hagstrum, Jonathan T.; McGeehin, John P.; Champion, Duane E.; Trusdell, Frank A.

    2006-01-01

    New mapping and 60 new radiocarbon ages define the age and distribution of latest Pleistocene and Holocene (past 13,000 years) lava flows at Haleakal? volcano, Island of Maui. Paleomagnetic directions were determined for 118 sites, of which 89 are in lava flows younger than 13,000 years. The paleomagnetic data, in conjunction with a reference paleosecular variation (PSV) curve for the Hawaiian Islands, are combined with our knowledge of age limitations based on stratigraphic control to refine age estimates for some of the undated lava flows. The resulting volumetric rate calculations indicate that within analytical error, the extrusion rate has remained nearly constant during the past 13,000 years, in the range 0.050.15 km3/kyr, only about half the long-term rate required to produce the postshield strata emplaced in the past ?1 Myr. Haleakal?'s eruptive frequency is similar to that of Hual?lai volcano on the Island of Hawaii, but its lava flows cover substantially less area per unit time. The reduced rates of lava coverage indicate a lower volcanic hazard than in similar zones at Hual?lai.

  2. Large landslides from oceanic volcanoes

    USGS Publications Warehouse

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

    1991-01-01

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

  3. Mingling processes at Panarea Volcano (Aeolian Islands, Italy): results from M73/2 cruise drilled cores

    NASA Astrophysics Data System (ADS)

    De Benedetti, A. A.; De Astis, G.; Raffaele, V.; Esposito, A.; Giordano, G.; Petersen, S.; Monecke, T.

    2012-04-01

    The last Meteor 73/2 cruise drilled several lava cores in the southern Tyrrhenian Sea, close to Panarea Island and surrounding islets (Aeolian archipelago, Italy), at depths comprised between 50 and 70 m bsl. These rocks - unconformably covered by unconsolidated lapilli tuffs - revealed different lithologies and mineralogical assemblages corresponding to different compositions (hereafter A & B), as then evidenced by ICP-MS analyses (major and trace elements) performed on selected rock-samples. The cores also displayed several, cm-sized, rounded enclaves of the A-type dispersed in the B-type. The petrographic study on textures and microprobe analyses on glass shards and mineral phases finally concurred in identifying two magmas with different history and quite complex interaction. Rock A is a holocrystalline shoshonite (SHO) - showing plagioclase (pl - An%=62-74) and clinopyroxene (cpx) as main phases, plus subordinate amphibole and biotite phenocrysts, rare and small olivines (Fo?89%) - which represents the first magma, usually in form of enclaves. Notably, the SHO shows intersertal vesicularity and scarce glass. Rock B is a porphyritic rhyodacite (RD) characterized by pl (An%=32-52), and biotite phenocrysts, with minor cpx phenocrysts and microphenocrysts. Pl and cpx show both alternate and normal zoning, and the former have frequent K-rich reaction rims. Similar mineral phases and frequent sanidine microlites characterize the alkali-trachyte glassy groundmass of rock B. This rock hosts the SHO and represent the most voluminous magma. Overall, these features indicate a quite complex history of magma interaction(s) as well as a polybaric crystallization, which lead the volatiles abundance and behaviour. From the study of the highly irregular edges observed along their contacts, we argue intrusive and visco-plastic relationships between A and B. Moreover, the presence of irregular vesicles and vugs bounded by pl microlites suggest an emplacement at shallow level where cooling favoured both slow degassing and pervasive crystallization. Textural and compositional data concur in indicating that the two magmas mingled at depth. Noteworthy, enclaves of a third rock type - very limited in volume - is present along some of the collected cores. It is a reddish low-porphyritic lava similar to the RD lava in terms of mineralogical composition, but showing a higher amount of microlites with smaller size if compared to the main RD host-rock. This could indicate that at some extent also mixing occurred. The multiple similarities of our rocks with lavas of the Panarea islets or other acid volcanics containing mafic-intermediate enclaves and outcropping on other Aeolian Islands, suggest that mafic magma uprising "within" resident magma with subsequent mingling is a recurrent process in these volcanic systems and may be the trigger for the eruption of acid melts.

  4. 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

  5. Plant diversity changes during the postglacial in East Asia: insights from Forest Refugia on Halla Volcano, Jeju Island.

    PubMed

    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

  6. Plate boundaries in the Woodlark Basin and Solomon Sea Region, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Goodliffe, A. M.; Cameron, M.

    2009-12-01

    The Solomon Sea and Woodlark Basin region of eastern Papua New Guinea is a tectonically complex region between the obliquely converging Pacific and Australian plates. Despite numerous marine geophysical surveys in the region, the exact nature of the tectonic boundaries between the Solomon Sea and the Woodlark Basin remains controversial. Marine geophysical data collected in the last decade provides additional insight into this region and clearly defines the boundaries of the Solomon Sea, Trobriand, Woodlark, and Australian plates. Multibeam bathymetry data collected in 2004 along the Trobriand Trough, together with seismic profiles across the trough, show a prominent deformation front in the trench that defines the southern boundary of the Solomon Sea plate. Petrologic data from volcanoes to the south of this boundary indicate that they have a subduction affinity. Heat flow profiles to the south of the plate boundary show a clear subduction signature. At the eastern termination of the Trobriand Trough the plate boundary forms a triple junction with the NE-SW trending Nubaru strike-slip fault. To the NE this major fault separates the Solomon Sea plate from the Woodlark plate. The morphology of this fault and a CMT solution indicate that it is right-lateral. To the SW the Nubaru strike-slip fault passes to the south of the Trobriand Trough, forming the southern boundary of the Trobriand plate (with the Trobriand Trough as the northern boundary). Further west the trend of the strike slip fault becomes more ENE-WSW. A significant extension component is evident as the fault passes to the north of Egum Graben and meets the Woodlark Basin spreading system at the current rifting to seafloor spreading transition directly to the east of Moresby Seamount. The revised tectonic model for this region has important implications for tectonic reconstructions that include an active rifting to spreading transition and prominent core complexes. In the past, models have assumed a simple two-plate system. The inclusion of the Trobriand plate at the rifting to spreading transition will change estimates of extension that have assumed that the system can be described by a single Euler pole directly to the WSW.

  7. The Solomon Sea eddy activity from a 1/36 regional model

    NASA Astrophysics Data System (ADS)

    Djath, Bughsin; Babonneix, Antoine; Gourdeau, Lionel; Marin, Frdric; Verron, Jacques

    2013-04-01

    In the South West Pacific, the Solomon Sea exhibits the highest levels of eddy kinetic energy but relatively little is known about the eddy activity in this region. This Sea is directly influenced by a monsoonal regime and ENSO variability, and occupies a strategical location as the Western Boundary Currents exiting it are known to feed the warm pool and to be the principal sources of the Equatorial UnderCurrent. During their transit in the Solomon Sea, meso-scale eddies are suspected to notably interact and influence these water masses. The goal of this study is to give an exhaustive description of this eddy activity. A dual approach, based both on altimetric data and high resolution modeling, has then been chosen for this purpose. First, an algorithm is applied on nearly 20 years of 1/3 x 1/3 gridded SLA maps (provided by the AVISO project). This allows eddies to be automatically detected and tracked, thus providing some basic eddy properties. The preliminary results show that two main and distinct types of eddies are detected. Eddies in the north-eastern part shows a variability associated with the mean structure, while those in the southern part are associated with generation/propagation processes. However, the resolution of the AVISO dataset is not very well suited to observe fine structures and to match with the numerous islands bordering the Solomon Sea. For this reason, we will confront these observations with the outputs of a 1/36 resolution realistic model of the Solomon Sea. The high resolution numerical model (1/36) indeed permits to reproduce very fine scale features, such as eddies and filaments. The model is two-way embedded in a 1/12 regional model which is itself one-way embedded in the DRAKKAR 1/12 global model. The NEMO code is used as well as the AGRIF software for model nestings. Validation is realized by comparison with AVISO observations and available in situ data. In preparing the future wide-swath altimetric SWOT mission that is expected to provide observations of small-scale sea level variability, spectral analysis is performed from the 1/36 resolution realistic model in order to characterize the finer scale signals in the Solomon sea region. The preliminary SSH spectral analysis shows a k-4 slope, in good agreement with the suface quasigeostrophic (SQG) turbulence theory. Keywords: Solomon Sea; meso-scale activity; eddy detection, tracking and properties; wavenumber spectrum.

  8. 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)

  9. The LLWBCs of the Solomon Sea depicted by altimetry and gliders

    NASA Astrophysics Data System (ADS)

    Gourdeau, L.; Melet, A.; Verron, J. A.; Kessler, W. S.; Dussurget, R.; Davis, R. E.

    2010-12-01

    The Solomon Sea with its intense Low Latitude Western Boundary Currents (LLWBCs) is a key region in the Pacific Ocean where equatorial and subtropical circulations are connected. Since the geography of the region is extremely intricate, with numerous islands and complex bathymetry, specifically reprocessed along-track data were utilized in this study in addition to standard gridded data. Track data appear especially helpful for documenting the fine structure of surface coastal currents. The annual variability of the boundary currents that emerged from altimetry compared quite well with the variability seen at the thermocline level on numerical simulations. At inter-annual time scales, western boundary current transport anomalies tend to counterbalance changes in western Equatorial Pacific warm water volume, confirming the phasing of South Pacific western boundary currents to ENSO. The highest SLA variability is concentrated in the eastern Solomon Sea, particularly at the mouth of Solomon Strait, where it is associated with a high eddy kinetic energy signal. An experimental glider monitoring of the LLWBCs, currently operated since August 2007, shows the huge variability of the transports in relation to ENSO conditions and eddy activity. The glider data are useful to test how the surface information from altimetry is representative of the dynamics at depth, whereas the satellite data are useful to interpret the along track glider data in a synoptic context.

  10. 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. ...

  11. Appreciating Unity in Diversity: An Interview with Andrew Solomon

    ERIC Educational Resources Information Center

    Peters, Dane L.

    2014-01-01

    The theme of the AMS 2014 Annual Conference is "Unity in Diversity," a concept that also describes the work of conference keynote speaker Andrew Solomon. Solomon is a writer and lecturer on psychology and politics; winner of the National Book Award; and an activist for LGBT [lesbian, gay, bisexual, and transgender] rights, mental health,

  12. 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.

  13. Space Qualified High Speed Reed Solomon Encoder

    NASA Technical Reports Server (NTRS)

    Gambles, Jody W.; Winkert, Tom

    1993-01-01

    This paper reports a Class S CCSDS recommendation Reed Solomon encoder circuit baselined for several NASA programs. The chip is fabricated using United Technologies Microelectronics Center's UTE-R radiation-hardened gate array family, contains 64,000 p-n transistor pairs, and operates at a sustained output data rate of 200 MBits/s. The chip features a pin selectable message interleave depth of from 1 to 8 and supports output block lengths of 33 to 255 bytes. The UTE-R process is reported to produce parts that are radiation hardened to 16 Rads (Si) total dose and 1.0(exp -10) errors/bit-day.

  14. Real-Time Reed-Solomon Decoder

    NASA Technical Reports Server (NTRS)

    Maki, Gary K.; Cameron, Kelly B.; Owsley, Patrick A.

    1994-01-01

    Generic Reed-Solomon decoder fast enough to correct errors in real time in practical applications designed to be implemented in fewer and smaller very-large-scale integrated, VLSI, circuit chips. Configured to operate in pipelined manner. One outstanding aspect of decoder design is that Euclid multiplier and divider modules contain Galoisfield multipliers configured as combinational-logic cells. Operates at speeds greater than older multipliers. Cellular configuration highly regular and requires little interconnection area, making it ideal for implementation in extraordinarily dense VLSI circuitry. Flight electronics single chip version of this technology implemented and available.

  15. An extended Reed Solomon decoder design

    NASA Technical Reports Server (NTRS)

    Chen, J.; Owsley, P.; Purviance, J.

    1991-01-01

    It has previously been shown that the Reed-Solomon (RS) codes can correct errors beyond the Singleton and Rieger Bounds with an arbitrarily small probability of a miscorrect. That is, an (n,k) RS code can correct more than (n-k)/2 errors. An implementation of such an RS decoder is presented in this paper. An existing RS decoder, the AHA4010, is utilized in this work. This decoder is especially useful for errors which are patterned with a long burst plus some random errors.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. Volcano spacing and plate rigidity

    SciTech Connect

    Brink, U. )

    1991-04-01

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

  18. The decoding of Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Mceliece, R. J.

    1988-01-01

    Reed-Solomon (RS) codes form an important part of the high-rate downlink telemetry system for the Magellan mission, and the RS decoding function for this project will be done by DSN. Although the basic idea behind all Reed-Solomon decoding algorithms was developed by Berlekamp in 1968, there are dozens of variants of Berlekamp's algorithm in current use. An attempt to restore order is made by presenting a mathematical theory which explains the working of almost all known RS decoding algorithms. The key innovation that makes this possible is the unified approach to the solution of the key equation, which simultaneously describes the Berlekamp, Berlekamp-Massey, Euclid, and continued fractions approaches. Additionally, a detailed analysis is made of what can happen to a generic RS decoding algorithm when the number of errors and erasures exceeds the code's designed correction capability, and it is shown that while most published algorithms do not detect as many of these error-erasure patterns as possible, by making a small change in the algorithms, this problem can be overcome.

  19. Dante's Volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

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

  20. 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....

  1. Dante's volcano

    NASA Astrophysics Data System (ADS)

    1994-09-01

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

  2. Observed Circulation in the Solomon Sea from SADCP data

    NASA Astrophysics Data System (ADS)

    Cravatte, S. E.; Ganachaud, A. S.; Eldin, G.; Kessler, W. S.; Dutrieux, P.

    2010-12-01

    The Solomon Sea, in the western tropical Pacific, is a major oceanic pathway connecting the tropics to the equator via low latitude western boundary currents. Shipboard acoustic Doppler current profiler data from 94 cruises over 20 years are used to describe the Solomon Sea mean circulation and its seasonal variability above 300m depth, providing an unprecedented detailed picture from observations. The circulation in the near-surface (20-100m) and thermocline (100-300m) layers are analyzed separately but found to have many similar features. The New Guinea Coastal Undercurrent enters the Solomon Sea east of the Louisiade Archipelago (15 Sv inflow above 300m), divides against the coast of New Britain forming two branches flowing westward and eastward. The westward branch previously observed flowing through Vitiaz Strait is found to transport 7-8 Sv in the upper 300m. The eastward branch exits the Solomon Sea through St. Georges Channel (1-2 Sv) and Solomon Strait (4-5 Sv) in the thermocline. At the surface, above about 100m, surface flow in Solomon St is southwestward. The seasonal variability can be documented in locations of sufficient data coverage. It is shown that this western boundary current system strengthens in June to August, during the southeasterly monsoon. A summary of transport variability in the straits of the Solomon Sea from individual cruises is also provided. Transports in the straits display some stable features, but also high non-seasonal variability.

  3. Links between the variability of the WBCs and the meso-scale eddy activity inside the Solomon Sea

    NASA Astrophysics Data System (ADS)

    Babonneix, A.; Gourdeau, L.; Djath, N.; Chaigneau, A.; Verron, J. A.; Marin, F.

    2012-12-01

    In the South West Pacific, the Solomon Sea exhibits the highest levels of eddy kinetic energy but relatively little is known about the eddy activity in this region. This Sea is directly influenced by a monsoonal regime and ENSO variability, and occupies a strategical location as the Western Boundary Currents exiting it are known to feed the warm pool waters and to be the main sources for the Equatorial UnderCurrent. During their transit in the Solomon Sea, the meso-scale activity is suspected to notably influence these WBCs. The objective of this study is to give an exhaustive description of these eddies based on an eddy detection algorithm and a tracking procedure applied both on altimetric data and model outputs. Nearly 20 years of 1/3 x 1/3 gridded SLA maps (provided by the AVISO project) are indeed currently available. However, the resolution of the AVISO dataset is not very well suited to match with the numerous islands bordering the Solomon Sea. Moreover, the finest structures cannot be observed with this dataset due to its relatively rough resolution. For this reason, we will confront these observations with the outputs of a 1/36 resolution model of the Solomon Sea. This model, after validation with the AVISO observations, will give access to finer scales and will represent smaller structures. The combined results will be used to describe the meso-scale eddy activity in the Solomon Sea. First, the eddy field will be depicted with the use of general properties such the eddy location, amplitude or the total area occupied. Then, the temporal variability of this meso-scale activity will be analyzed by computing its annual cycle and interannual variations, and put in regard with the regional oceanic circulation variability. In each case, the discrepancies between cyclonic and anticyclonic eddies will also be discussed.

  4. Mapping Between Distinct Reed-Solomon Codes

    NASA Technical Reports Server (NTRS)

    Perlman, Marvin

    1994-01-01

    One-to-one mapping between two Reed-Solomon (RS) codes devised to enable decoder designed for one of codes to operate on other one also. Codes in question must have same N and K parameters (defined below) but otherwise be two distinct RS codes. Mapping intended to enable same ground-based decoder to decode telemetry signals from two spacecraft in two different RS codes of (N,K) = (255,223). Also useful in purely terrestrial data communications and in optical and magnetic recording and playback of digitized audio and video signals. Implemented in interface circuitry and/or software to enable communication between coding systems of different manufacturers using different RS codes within same (N,K) family.

  5. 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 m 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

  6. Mahukona: The missing Hawaiian volcano

    SciTech Connect

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

    1990-11-01

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

  7. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

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

  8. High-resolution locations of triggered earthquakes and tomographic imaging of Kilauea Volcano's south flank

    NASA Astrophysics Data System (ADS)

    Syracuse, Ellen M.; Thurber, Clifford H.; Wolfe, Cecily J.; Okubo, Paul G.; Foster, James H.; Brooks, Benjamin A.

    2010-10-01

    The spatiotemporal patterns of seismicity beneath Kilauea's south flank give insight to the structure and geometry of the decollement on which large, tsunamigenic earthquakes have occurred, and its relation to slow slip events (SSEs), which have been observed every 1 to 2 years since 1997. In order to record earthquakes triggered by a SSE that was predicted to occur in March 2007, a temporary network of 20 seismometers was deployed on Kilauea's south flank, termed the SEQ network. While the SSE did not occur until 17 June 2007, theSEQ network recorded over 3000 earthquakes, including those triggered by the SSE. We relocate hypocenters of volcano-tectonic earthquakes and invert for P and S wave velocity structure using waveform cross-correlation and double-difference tomography using data from the SEQ network and the permanent Hawaii Volcano Observatory network (HVO) data, with additional data from other previous temporary arrays. The best-constrained hypocenters, recorded by both the SEQ and HVO networks, indicate the decollement as a subhorizontal layer of seismicity at 8 km depth less than 1 km thick in most areas, with the western portion of the decollement dipping to the southeast. The seismicity triggered by the June 2007 SSE includes over 400 earthquakes overlapping with the southern edge of the decollement seismicity. A shallower swarm of earthquakes also occurred between 2 and 7 km depth in April 2007 near Apua Point, and may have been indirectly triggered by the Mw 8.1 Solomon Islands earthquake at 6000 km distance, which occurred 48 h prior to the beginning of the swarm.

  9. Retrieving 65 years of volcano summit deformation from multitemporal structure from motion: The case of Piton de la Fournaise (La Runion Island)

    NASA Astrophysics Data System (ADS)

    Derrien, Allan; Villeneuve, Nicolas; Peltier, Aline; Beauducel, Franois

    2015-09-01

    The structure from motion photogrammetry technique enables use of historical airborne photography to achieve high-resolution 3-D terrain models. We apply this method on Piton de la Fournaise volcano (La Runion), which allows a unique opportunity to retrieve high-resolution (1.5-0.11 m) digital elevation models and precise deformation maps of the volcano since 1950. Our results provide evidence that the summit volume increased throughout the study period, at a stable rate of 2.2 Mm3/yr between 1950 and 2015, with an acceleration up to 8.0 Mm3/yr prior to the major 2007 eruption that was accompanied by summit caldera collapse. At the same time, summit deformation was asymmetric, with 9.2 2.5 m of eastward seaward displacement and 1.3 2.5 m to the west during 1950-2015. Our results reveal a temporal evolution in the volcano magma influx rate and deformation. Tracking these fluxes and the long-lived preferential eastern motion is crucial to mitigate risks associated to flank destabilization.

  10. Observed circulation in the Solomon Sea from SADCP data

    NASA Astrophysics Data System (ADS)

    Cravatte, Sophie; Ganachaud, Alexandre; Duong, Quoc-Phi; Kessler, William S.; Eldin, Grard; Dutrieux, Pierre

    2011-01-01

    The Solomon Sea, in the western tropical Pacific, is part of a major oceanic pathway for waters connecting the tropics to the equator via low latitude western boundary currents. Shipboard Acoustic Doppler Current Profiler data from 94 various cruises and transits are used to describe the Solomon Sea mean circulation and its seasonal variability above 300 m depth, providing an unprecedently detailed picture from observations. The circulation in the near-surface (20-100 m) and thermocline (100-300 m) layers were analyzed separately but found to have many similar features. They are compared with circulations inferred from hydrological and satellite data. The New Guinea Coastal Undercurrent enters the Solomon Sea east of the Louisiade Archipelago (15 Sv inflow above 300 m), splits and rejoins around the Woodlark Chain, then divides against the coast of New Britain forming two branches flowing westward and eastward. The westward branch has been previously observed flowing through Vitiaz Strait; in the present SADCP data this transport is found to be 7-8 Sv in the upper 300 m. The eastward branch has been suspected and occurs in some models; it exits the Solomon Sea through St. Georges Channel (1-2 Sv) and Solomon Strait (4-5 Sv) in the thermocline. At the surface, waters enter the Solomon Strait from the north. The seasonal variability can be documented in locations of sufficient data coverage. It is shown that this western boundary system strengthens in June-August. A summary of transport variability in the straits of the Solomon Sea from individual cruises is also presented. Transports in the straits display some stable features, but also high non-seasonal variability.

  11. Volcano-Tectonic Deformation at Taal Volcano, Philippines

    NASA Astrophysics Data System (ADS)

    Hamburger, M. W.; Galgana, G.; Corpuz, E.; Bartel, B.

    2004-12-01

    Taal Volcano, located in southern Luzon, Philippines, is an unusual, tholeiitic volcano situated within a calc-alkaline arc. It is one of the most active volcanic centers in the Philippines, with some 33 historic volcanic eruptions over the past four centuries. Volcanism at Taal is at least partly tectonically controlled, suggested by its location at the intersection of regional fault structures and by the location and shape of both Taal's caldera and Volcano Island. The alignment of modern eruption centers, are controlled by regional and local structures. Here, we review geomorphic and geodetic observations that constrain both tectonic and volcanic deformation in the vicinity of Taal volcano. We use GPS measurements from a 52-station GPS network measured from 1996 - 2001 to investigate overall plate interaction and microplate (intra-arc) deformation. The velocity field indicates that the majority of the Philippine Sea - Eurasia plate convergence is taking place west of Luzon, presumably largely by subduction at the Manila trench. A relatively small fraction of the convergence appears to be taking place within Luzon or across the East Luzon trough. The major intra-arc deformation is accommodated by strike-slip motion along the Philippine Fault, ranging from 25-40 mm/yr left-lateral slip. Detailed measurements in southern Luzon also indicate significant intra-arc deformation west of the Philippine Fault. GPS measurements in southwestern Luzon indicate significant motion within the arc, which could be explained by 11-13 mm/yr of left-lateral shear along the "Macolod Corridor", within which Taal Volcano resides. A dense network of continuous single- and dual-frequency GPS receivers at Taal Volcano, Philippines reveals highly time-variable deformation behavior, similar to that observed at other large calderas. While the caldera has been relatively quiescent for the past 2-3 years, previous deformation includes two major phases of intra-caldera deformation, including two phases of inflation and deflation in 1998-2000. The February-November 2000 period of inflation was characterized by approximately 120 mm of uplift of the center of Volcano Island relative to the northern caldera rim, at average rates up to 216 mm/yr. The source of deflation in 1999 was modeled as a contractional Mogi point source centered at 4.2 km depth beneath Volcano Island; the source of inflation in 2000 was modeled as a dilatational Mogi point source centered at 5.2 km depth beneath Volcano Island. The locations of the two sources are indistinguishable within the 95% confidence estimates. Modeling using a running four-month time window from June 1999-March 2001 reveals little evidence for source migration. We find marginal evidence for an elongate source whose long axis is oriented NW-SE, paralleling the caldera-controlling fault system. We suggest that the two periods of inflation observed at Taal represent episodic intrusions of magma into a shallow reservoir centered beneath Volcano Island whose position is controlled at least in part by regional tectonic structures.

  12. 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.

  13. Exploiting the cannibalistic traits of Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Collins, O.

    1993-01-01

    In Reed-Solomon codes and all other maximum distance separable codes, there is an intrinsic relationship between the size of the symbols in a codeword and the length of the codeword. Increasing the number of symbols in a codeword to improve the efficiency of the coding system thus requires using a larger set of symbols. However, long Reed-Solomon codes are difficult to implement and many communications or storage systems cannot easily accommodate an increased symbol size, e.g., M-ary frequency shift keying (FSK) and photon-counting pulse-position modulation demand a fixed symbol size. A technique for sharing redundancy among many different Reed-Solomon codewords to achieve the efficiency attainable in long Reed-Solomon codes without increasing the symbol size is described. Techniques both for calculating the performance of these new codes and for determining their encoder and decoder complexities is presented. These complexities are usually found to be substantially lower than conventional Reed-Solomon codes of similar performance.

  14. 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

  15. Eruptions of Taal Volcano 1976-1977

    NASA Astrophysics Data System (ADS)

    Wolfe, John A.

    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 major eruption occurred when a channel was opened to the lake by an explosion on September 28, 1965 (see Figure 1).

  16. Obituary: Philip M. Solomon, 1939-2008

    NASA Astrophysics Data System (ADS)

    Scoville, Nick

    2009-01-01

    Philip Solomon, one of the pioneers and leading researchers in molecular astrophysics, died on 30 April 2008 at his apartment on the upper west side of Manhattan after a battle with cancer. His pioneering research included both theoretical and very extensive observational studies of stellar atmospheres, interstellar molecules, high redshift galaxies, and the Earth's stratosphere. Phil was Distinguished Professor at The State University of New York [SUNY], Stony Brook, where he had been since 1974. Phil was born on 29 March 1939 in Manhattan, New York City, to Nat and Betty Solomon. Nat Solomon was a labor organizer and a printer. Phil attended the University of Wisconsin, where he received his BS in 1959 and where he met his future wife Sheila who was studying art. His Ph.D., "On the Role of Light Molecules in Astrophysics," was also from the University of Wisconsin under the guidance of Art Code and Bob Bless. After postdoctoral positions at Princeton and lectureships at Columbia and the University of California, San Diego, Phil spent two years as a Professor at the University of Minnesota. After two years at the Institute for Advanced Study in Princeton, he came to SUNY, Stony Brook, as Professor of Astronomy in the Department of Earth and Space Sciences. In 1988 Phil was selected as a Humboldt Senior Distinguished Scientist, and, in 1999, he was honored with the rank of Distinguished Professor at SUNY. Phil took sabbatical and other leaves at Churchill College and the Institute of Astronomy, Cambridge; the Institute for Advanced Study; l'Ecole Normale Superieure, Paris; Institut d'Astrophysique, Paris; and the Institut de Radioastronomie Millimetrique [IRAM], France. Phil published more than 160 papers and supervised seven Ph.D. students. He served on numerous review, visiting, and advisory panels. Phil's first theoretical research focused on opacity and abundance of light molecules such as H2, CO, and CN in stellar atmospheres, but then shifted quickly to the formation, excitation, and astrophysics of interstellar molecules, which had just been discovered in the late 1960s. In 1969, Phil and Chandra Wickramasinghe were among the first to suggest that the denser interstellar clouds, which were deficient in atomic hydrogen, were principally molecular hydrogen with the H2 formed on the surface of cold dust grains and protected from dissociating UV by a self-shielding H2 layer at the cloud surface. With L. Lucy, Phil then developed the radiative transfer and mass-loss mechanism operative in hot OB star winds and QSOs--where the radiative momentum is absorbed in resonance lines of ions. In the late 1960s and early 1970s, the detection and mapping of interstellar molecules moved rapidly from the early discoveries of maser emission in H2O and OH to the thermal emission lines of simple molecules like CO, CN, CS, and HCN, to more complex species containing up to thirteen atoms. Phil was a major force in pushing these new detections and in using the thermal emission as astrophysical probes. This explosive growth of spectroscopic detections occurred primarily as a result of Phil's collaborations with A. Penzias, K. Jefferts, R. Wilson, and P. Thaddeus, along with other competing groups using the NRAO 36-foot telescope at Kitt Peak. This was a most exciting period with the mm-wave window finally accessible to spectroscopy and each observing run on the telescope typically yielded one or two new detections. Phil was probably the one most responsible for providing the astrophysical motivation to push the technology towards mm-wavelengths. He clearly elucidated the fact that high densities were required for the thermal excitation of the higher dipole moment molecules such CS and HCN--at the same time pointing out, for the first time, the critical role of line photon trapping in the optically thick lines. In collaboration with N. Scoville and D. Sanders, Phil initiated the early surveys of CO emission from the Milky Way molecular gas. They first pointed out that the molecular gas resides largely in self-gravitating clouds (not in pressure equilibrium with the diffuse atomic and ionized gas) and coined the term Giant Molecular Clouds. They also discovered that the molecular gas had a Galactic distribution very different from the atomic gas--a massive central concentration within 300 pc of the Galactic center and the molecular cloud "ring" at 4 to 8 kpc radius. Throughout this work, he clearly elucidated the astrophysical importance of the dense molecular clouds as the sites of virtually all star formation. During this period, Phil, in collaboration with W. Klemperer, provided important theoretical insight into the formation of simple diatomic molecules via gas-phase charge exchange reactions. As the sensitivity of mm-wave receivers improved, Phil extended the observations of CO and HCN emission first to nearby galaxies in collaboration with J. Barrett and L. Sage and then to higher luminosity, more-distant objects with Y. Gao, D. Downes, and P. Vanden Bout. Solomon and Gao very significantly showed that for the most luminous infrared galaxies, the infrared luminosities were linearly proportional to the amount of dense, star-forming gas (as traced by HCN) and hence, they argued, that the source of luminosity could be entirely star formation rather than quasar activity. With Downes, Phil was introduced to mm-wave interferometry (at last, I should say, since he was basically a single-dish astronomer at heart), and they were among the first to produce high-resolution images of the most luminous infrared galaxies. Phil's most recent work, in collaboration with Vanden Bout, Carilli, and Maddalena to detect CO and HCN from the highest redshift galaxies was on-going, but resulted in a recent Annual Reviews paper that provides a forward look to the future of this field. Phil also realized that mm-wave spectroscopy could be used for remote sensing of the terrestrial stratosphere to trace the abundance of ClO and hence monitor the ozone layer depletion. This work, in collaboration with R. deZafra, J. Barrett, and A. Parrish, led to their setting up remote, automated observing systems in Antarctica and in Hawaii; these efforts continued over twenty years up to the present. For those of us who collaborated with Phil, he will be greatly missed. Phil had a keen sense for interesting and significant science; he had a real enthusiasm for discovery; and he enjoyed the competition of forefront scientific research where recognition of significance was vital but where discussion of interpretation was rational, albeit with strong argument. The pleasure of an observing run with Phil was supreme due to his enthusiasm and focus on the astrophysics; these runs also were creative since if the original plans did not quite pan out, he was always ready to modify the observations to take advantage of what one learned from the data coming into the telescope. Often this resulted in much better science--in contrast to the current paradigm with fixed observing programs and queue observing. Phil was also a major presence at scientific meetings giving stimulating talks and provoking challenging discussions. Phil is survived by his wife Sheila, daughter Nina, son-in-law John, granddaughter Sarah, and brother Mark.

  17. 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.

  18. VLSI single-chip (255,223) Reed-Solomon encoder with interleaver

    NASA Technical Reports Server (NTRS)

    Hsu, In-Shek (Inventor); Deutsch, Leslie J. (Inventor); Truong, Trieu-Kie (Inventor); Reed, Irving S. (Inventor)

    1990-01-01

    The invention relates to a concatenated Reed-Solomon/convolutional encoding system consisting of a Reed-Solomon outer code and a convolutional inner code for downlink telemetry in space missions, and more particularly to a Reed-Solomon encoder with programmable interleaving of the information symbols and code correction symbols to combat error bursts in the Viterbi decoder.

  19. 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.

  20. Iceland: Eyjafjallajkull Volcano

    Atmospheric Science Data Center

    2013-04-17

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

  1. Investigating the Gao & Solomon Relationship with MALT90

    NASA Astrophysics Data System (ADS)

    Stephens, Ian; Jackson, James M.; Whitaker, John Scott; Contreras, Yanett; Foster, Jonathan B.; Guzman, Andres; Sanhueza, Patricio; Rathborne, Jill

    2016-01-01

    In an survey of 53 galaxies, Gao & Solomon (2004) found a tight linear relationship between the infrared luminosity (a proxy for the star formation rate) and the HCN(1-0) luminosity, which is known as the Gao & Solomon relationship. Wu et al. (2005, 2010) found that this relationship extends from these extragalactic sources to the much less luminous Galactic clumps (~1 pc scales), and posited that there exists a fundamental unit for the ratio between infrared luminosity and dense gas mass for high-mass star-forming clumps. The luminosities of the Gao & Solomon (2004) galaxies could then be explained as a summation of this fundamental unit in the form of high-mass star-forming clumps. We test this explanation and other possible origins of the Gao-Solomon relationship using high-density tracers (including HCN(1-0), N2H+(1-0), HCO+(1-0), HNC(1-0), HC3N(10-9), and C2H(1-0)) for ~400 Galactic clumps from the Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey. Along with ancillary data, we find that this fundamental unit is not likely to exist at the clump-scale. Specifically, there are not enough high-mass clumps in the Milky Way to achieve the total expected luminosity of the Galaxy. Extended infrared emission, which often lacks high-mass clumps, adds significant (and probably dominant) emission to the total infrared luminosity of a galaxy. Low-mass clumps appear to add a significant, if not dominant, component to a galaxy's total HCN(1-0) luminosity. We suggest that Gao & Solomon relationship could be a result of a universal large-scale star formation efficiency, initial mass function, clump mass function, and core mass function. The power-law slope of the Gao & Solomon relationship probably depends on the critical density of the tracer and the median density of the galaxy, as suggested in theoretical simulations.

  2. A Solomon link through an interwoven molecular grid.

    PubMed

    Beves, Jonathon E; Danon, Jonathan J; Leigh, David A; Lemonnier, Jean-Franois; Vitorica-Yrezabal, Iigo J

    2015-06-22

    A molecular Solomon link was synthesized through the assembly of an interwoven molecular grid consisting of four bis(benzimidazolepyridyl)benzthiazolo[5,4-d]thiazole ligands and four zinc(II), iron(II), or cobalt(II) cations, followed by ring-closing olefin metathesis. NMR spectroscopy, mass spectrometry, and X-ray crystallography confirmed the doubly interlocked topology, and subsequent demetalation afforded the wholly organic Solomon link. The synthesis, in which each metal ion defines the crossing point of two ligand strands, suggests that interwoven molecular grids should be useful scaffolds for the rational construction of other topologically complex structures. PMID:25960366

  3. A Solomon Link through an Interwoven Molecular Grid**

    PubMed Central

    Beves, Jonathon E; Danon, Jonathan J; Leigh, David A; Lemonnier, Jean-Franois; Vitorica-Yrezabal, Iigo J

    2015-01-01

    A molecular Solomon link was synthesized through the assembly of an interwoven molecular grid consisting of four bis(benzimidazolepyridyl)benzthiazolo[5,4-d]thiazole ligands and four zinc(II), iron(II), or cobalt(II) cations, followed by ring-closing olefin metathesis. NMR spectroscopy, mass spectrometry, and X-ray crystallography confirmed the doubly interlocked topology, and subsequent demetalation afforded the wholly organic Solomon link. The synthesis, in which each metal ion defines the crossing point of two ligand strands, suggests that interwoven molecular grids should be useful scaffolds for the rational construction of other topologically complex structures. PMID:25960366

  4. Explosive activity of the summit cone of Piton de la Fournaise volcano (La Réunion island): A historical and geological review

    NASA Astrophysics Data System (ADS)

    Michon, Laurent; Di Muro, Andrea; Villeneuve, Nicolas; Saint-Marc, Cécile; Fadda, Pierluigi; Manta, Fabio

    2013-08-01

    Summit explosive activity and collapses that form pit craters and calderas represent major volcanic hazards on a dominantly effusive, frequently active volcano like Piton de la Fournaise. Only three summit collapse events (1986, 2002, 2007) have been recorded since the foundation of the Piton de la Fournaise volcano observatory (OVPF) in 1979, and two of them (1986 and 2007) were associated with weak phreatic activity. At Piton de la Fournaise, the normal explosive activity consists of short-lived and mild (< 20 m-high) lava fountains, which quickly evolve into strombolian activity during the eruptions. Based on comprehensive literature review and high-resolution image analysis of surface outcrops and summit caldera walls, we reconstructed the time distribution of recent explosive events (phreatomagmatic; phreatic) and their link with summit collapses and lateral (flank) effusive eruptions. In historical time (post-1640 CE), we recognise two main clusters of explosive events. Frequent and violent phreatomagmatic to phreatic explosions occurred during the oldest cluster (1708-1878) and alternated with long-lasting periods (years to decades) of summit effusive activity. In contrast, scarce, and on average, weak explosions occurred during the youngest cluster (1897-2012), when discrete and short-lived (< 6 months) effusive eruptions represent the main eruptive dynamics. Historical summit collapses (pit craters and caldera), all localised at the top of the summit cone, were related to voluminous lateral eruptions and were followed by a significant decrease in eruptive rate. However, magma draining during lateral eruptions was not systematically associated with summit collapses or explosions. The long-lasting occurrence of magma at very shallow depth below the volcano summit, followed by a rapid lateral drainage, apparently represents a critical condition favouring magma-groundwater interaction to produce explosive activity. The prehistoric growth of the Piton de la Fournaise summit cone results chiefly from long-lasting to continuous activity, centred below its western side (Bory crater containing lava lakes). High lava fountains, long-lasting effusive activity, lava lakes, ash plumes and block ejections were common types of eruptive dynamics in the historical past, between 1640 and 1878. In this perspective, short-lived, small volume eruptions and long pauses, up to six years, during the last century of activity of Piton de la Fournaise can be considered as a lull, despite the high frequency of eruption (1 eruption/9 months on average). Temporal and spatial variations in recurrence rate and eruptive dynamics of basaltic volcanism, such as those recognised at Piton de la Fournaise, should be considered in the formulation of hazard assessments and in the interpretation of precursory patterns.

  5. 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.

  6. Natural hazards on the island of Hawaii

    USGS Publications Warehouse

    Peterson, D.W.; Mullineaux, D.R.

    1977-01-01

    The island of Hawaii and the other islands of the Hawaiian chain are products of volcanic eruptions. Lava flows from hundreds of thousands of eruptions through countless centuries have built the Hawaiian Islands. Some volcanoes on the island of Hawaii have been very active during historic time, and similar activity is expected to continue throughout the foreseeable future.

  7. A spatter-forming, large-scale paroxysm at Stromboli Volcano (Aeolian Islands, Italy): insight into magma evolution and eruption dynamics

    NASA Astrophysics Data System (ADS)

    La Felice, Sonia; Landi, Patrizia

    2011-11-01

    This study focuses on a pyroclastic sequence related to a large-scale paroxysm that occurred during the seventeenth century ad and which can be considered one of the most powerful and hazardous explosive events at the volcano in the past few centuries. Paroxysms are energetic, short-lived explosions which sporadically interrupt normal Strombolian activity at Stromboli and commonly erupt a deep-derived, volatile-rich crystal-poor high-potassium basalt ("low porphyricity" (LP)), together with a shallow, degassed crystal-rich high-potassium to shoshonitic basalt ("high porphyricity" (HP)), which feed normal activity at the volcano. The studied deposit, crops out along the flanks of Sciara del Fuoco and, from base to top, consists of: (1) a layer of HP and LP ash and lapilli; (2) an unwelded layer of coarse HP lapilli and flattened dark scoriae; (3) weakly welded spatter made up of dense HP pyroclasts at the base, overlain by strongly vesicular LP clasts. The textural and chemical zoning of minerals and the glass chemistry of the LP products record repeated mafic recharge events, mixing with an old mushy body and episodes of rapid crystallization due to sudden degassing. Collapse of a foam layer originated by deep degassing probably triggered this large-scale, spatter-forming paroxysm. Decompression induced rapid degassing and vesiculation of the deep volatile-rich magma. The rapid ascent of the foamy magma blob pushed the shallow HP magma out and finally produced a fire fountain that emplaced the LP portion of the spatter.

  8. Joint Synchronization Of Viterbi And Reed-Solomon Decoders

    NASA Technical Reports Server (NTRS)

    Statman, Joseph I.; Chauvin, Todd H.; Cheung, Kar-Ming; Rabkin, Jay; Belongie, Mignon L.

    1995-01-01

    Synchronization times reduced to reduce loss of data. Scheme for decoding received doubly encoded binary-data signal provides for joint synchronization of two decoders. Applies to concatenated error-correcting channel coding communication system in which, at transmitter, data first encoded by interleaved Reed-Solomon code (block code), then by convolutional code.

  9. Single-Chip VLSI Reed-Solomon Decoder

    NASA Technical Reports Server (NTRS)

    Shao, Howard M.; Truong, Trieu-Kie; Hsu, In-Shek; Deutsch, Leslie J.

    1988-01-01

    Efficient utilization of computing elements reduces size while preserving throughput. VLSI architecture is pipeline Reed-Solomon decoder for correction of errors and erasures. Uses transform circuit to compute syndrome polynomial. Erasure information enters decoder as binary sequence. Applied to variety of digital communications involving error-correcting RS codes.

  10. Limping or Flying? Psychoanalysis, Afrocentrism, and "Song of Solomon."

    ERIC Educational Resources Information Center

    Tidey, Ashley

    2000-01-01

    Explores the possibility of seeing in Toni Morrison's novel, "Song of Solomon," the co-existence of two narratives of subjectivity. Examines the extent to which the application of a Western and non-Western narrative of subject formation yields conflicting interpretations of the novel and, in particular, the novel's ending. (SC)

  11. Fast transform decoding of nonsystematic Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Truong, T. K.; Cheung, K.-M.; Reed, I. S.; Shiozaki, A.

    1989-01-01

    A Reed-Solomon (RS) code is considered to be a special case of a redundant residue polynomial (RRP) code, and a fast transform decoding algorithm to correct both errors and erasures is presented. This decoding scheme is an improvement of the decoding algorithm for the RRP code suggested by Shiozaki and Nishida, and can be realized readily on very large scale integration chips.

  12. 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.

  13. Kilauea volcano eruption seen from orbit

    NASA Technical Reports Server (NTRS)

    1993-01-01

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

  14. A scale for ranking volcanoes by risk

    NASA Astrophysics Data System (ADS)

    Scandone, Roberto; Bartolini, Stefania; Martí, Joan

    2016-01-01

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

  15. Soufriere Hills Volcano

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

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

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

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

    Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA's Earth Science Enterprise, a long- term research effort to understand and protect our home planet. Through the study of Earth, NASA will help to provide sound science to policy and economic decision-makers so as to better life here, while developing the technologies needed to explore the universe and search for life beyond our home planet.

    Size: 40.5 x 40.5 km (25.1 x 25.1 miles) Location: 16.7 deg. North lat., 62.2 deg. West long. Orientation: North at top Image Data: ASTER bands 1,2, and 3. Original Data Resolution: 15 m Date Acquired: October 29, 2002

  16. Eruptive activity of the summit cone of Piton de la Fournaise volcano (La Réunion island): a historical and geological review.

    NASA Astrophysics Data System (ADS)

    Di Muro, Andrea; Michon, Laurent; Villeneuve, Nicolas; Saint-Marc, Cecile

    2013-04-01

    Summit explosive activity and collapses represent major volcanic hazards on a dominantly effusive and frequently active volcano like Piton de la Fournaise. Only three summit collapse events (1986, 2002 and 2007) have been recorded since the foundation of the Piton de la Fournaise volcano observatory (OVPF) in 1979 and two of them (1986 and 2007) were associated with weak phreatic activity. Except during these three events, most eruptions consist in short short-lived (< 3 hours) and mild (< 20 m-high) lava fountains quickly evolving into strombolian activity. Based on a comprehensive literature review and a high-resolution image analysis of surface outcrops and summit caldera walls, we reconstructed the time distribution of recent explosive events and their link with summit collapses and lateral effusive eruptions. In historical times (post-1640 AD), we recognize two main clusters of explosive events. Frequent and violent phreatomagmatic to phreatic explosions occurred during the oldest cluster (1708-1878) characterized by long-lasting summit effusive activity. On the contrary, weak and scarce explosions occurred during the youngest cluster (1897-2012), in which discrete and often short-lived effusive eruptions represent the main eruptive dynamics. Historical summit collapses (pit craters to caldera), all localized at the top of the summit cone, were related to voluminous lateral eruptions and were followed by a significant decrease in eruptive rate. However, many lateral eruptions were not associated with summit collapses or explosions. The long-lasting occurrence of magma at very shallow depth represents thus a critical condition to produce summit explosive activity. The pre-historic building of Piton de la Fournaise summit cone results from a long-lasting to continuous activity centered below its western side (Bory crater/lava lakes). Frequent and large lava fountains and long-lasting lava lakes represented an important dynamics in this recent past. In this perspective, the last century of activity of Piton de la Fournaise can be considered as a lull, in spite of its high frequency (1 eruption / 9 months on average).

  17. The off-shore continuation of an active basaltic volcano: Piton de la Fournaise (Runion Island, Indian Ocean); structural and geomorphological interpretation from sea beam mapping

    NASA Astrophysics Data System (ADS)

    Lnat, Jean-Franois; Vincent, Pierre; Bachlery, Patrick

    1989-01-01

    In 1984 a Sea Beam survey of the submarine east flank of Piton de la Fournaise was performed with R/V "Jean Charcot". Three main types of volcanic or volcano-tectonic features have been identified: (1) The subaerial NE and SE volcanic rift zones of Piton de la Fournaise do not extend more than about five kilometers offshore. Unlike typical Hawaiian rift zones, which form narrow (2-4 km) ridges extending tens of kilometers from the summit, the active rift zones of Piton de la Fournaise widen downslope, attaining more than 10 km at their front. (2) The submarine extension of the Grand Brl slide is larger than the subaerial portion. The entire slide forms a 7 24 km scar bounded by two ramparts to the north and south. The slumped material may have moved as a debris flow, forming a large talus downslope of the slide. However, the submarine counterpart of the south area of the Grand Brl seems to be composed by a slumped block whose structure is apparently not disturbed. (3) Another prominent feature is a conspicuous topographic high that occupies nearly all the center of the surveyed zone. This "cast flank submarine plateau" cannot be associated with any active structure of Piton de la Fournaise. Its surface generally dips gently (2-3), and its northern and southern flanks are extensively cut by landslides. Cones of variable dimensions are observed on the plateau and farther to the east. Three hypotheses are examined to account for the origin of this morphology: (a) remnant flank of an ancestral Fournaise volcano associated with a large buried intrusion found by drilling beneath the Grand Brl; (b) distinct volcanic massif or (c) material of a huge and ancient landslide. The geophysical data show that the western part of this submarine plateau is reversely magnetized and associated with a moderate positive gravity anomaly. This confirms that, as suggested by the bathymetric analysis, this part of the plateau is relatively coherent. Conversely, the eastern portion of the plateau appears to be poorly magnetized and composed of low-density material, probably chaotic materials derived from landslides. The reversed magnetization of the western part shows that the whole structure is older than 0.7 Ma. These results show that the volcanic history of Piton de la Fournaise is more complex than previously thought.

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

    USGS Publications Warehouse

    Clague, David A.; Sherrod, David R.

    2014-01-01

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

  19. 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.

  20. 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

  1. 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

  2. Seismic Structure Beneath Taal Volcano, Philippines

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The very active Taal Volcano is situated 60 km south of Metro Manila in the southern part of Luzon Island. Based on its frequent explosive eruptions and high potential hazards to nearby population of several million, Taal Volcano is chosen as one of the 15 most dangerous "Decade Volcanoes" in the world. We deployed a temporary seismic network consisting of 8 stations since March 2008. The temporal network was operated from late March 2008 to mid March 2010 and recorded over 2270 local earthquakes. In the early data processing stages, unexpected linear drifting of clock time was clearly identified from ambient noise cross-correlation functions for a number of stations. The drifting rates of all problematic stations were determined as references to correct timing errors prior to further processing. Initial locations of earthquakes were determined from manually picking P- and S-phases arrivals with a general velocity model based on AK135. We used travel times of 305 well-located local events to derive a minimum 1-D model using VELEST. Two major earthquake groups were noticed from refined locations. One was underneath the western shore of Taal Lake with a linear feature, and the other spread at shallower depths showing a less compact feature around the eastern flank of Taal Volcano Island. We performed seismic tomography to image the 3D structure beneath Taal Volcano using a well-established algorithm, LOTOS. Some interesting features are noted in the tomographic results, such as a probable solidified past magma conduit below the northwestern corner of Taal Volcano Island, characterized by high Vp, Vs, and low Vp/Vs ratio, and a potential large hydrothermal reservoir beneath the central of Taal Volcano Island, characterized by low Vs and high Vp/Vs ratio. Combining the results of seismicity and tomographic images, we also suggest the potential existence of a magma chamber beneath the southwestern Taal Lake, and a magma conduit or fault extending from there to the northwestern shore of Taal Lake. Such magmatic signatures have never been reported in previous studies, suggesting that new eruption centers might be forming in places away from the historical craters on Taal Volcano Island.

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

    USGS Publications Warehouse

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

    2008-01-01

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

  4. 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

  5. The 2005-2006-eruption of the Barren Volcano, Andaman Sea: Evolution of basaltic magmatism in island arc setting of Andaman-Java subduction complex

    NASA Astrophysics Data System (ADS)

    Pal, Tapan; Raghav, Sanjeev; Bhattacharya, Anindya; Bandopadhyay, P. C.; Mitra, Sumit K.; Renjit, M. L.; Sankar, M. S.; Ghosh, Biswajit

    2010-07-01

    The Barren Volcano located in the volcanic chain of Burma-Java subduction complex became active during 2005-2006 initially as Strombolian and later on as sub-Plinian type ejecting out ash laden grey smoke and coarse pyroclasts. The pyroclasts are represented by vesiculated (20-30 vol.% vesicle) porphyritic basaltic rock where the phenocrysts constituting 20-25 vol.% of the total bulk are represented by plagioclase (18-25 vol.%), olivine (1-4%), clinopyroxene (0.5-2.5 vol.%) and few iron oxides. Olivine of the 2005-lava shows a variation in Fo content from core (Fo 81-85) to rim (Fo 73-75) but those in the 2006-lava show a uniform composition from core to rim (Fo 75-78). Feldspar grains of both the 2005 and 2006-eruptions are normally zoned, with a variation from core (An 93-80) to rim (An 76-55). The major oxides show basaltic composition for the 2005-lava and basaltic to basaltic andesite for the 2006-lava. Abundances of plagioclase phenocrysts, poorly hydrous glass inclusions in the phenocrysts, rarity of the mafic phase and high Zr content (69-75 ppm) are suggestive of the very poorly hydrous nature of magma. The calculated fractional crystallisation trend show the differences in the 2005-lava and 2006-lava where the former show accumulated nature and the latter indicates evolved path. The major oxides and trace elements patterns indicate that both the lava had a different parental composition and the 2006-lava was subjected to fractional crystallisation. The magmatic evolution is explained by the mantle diapir model where the almost anhydrous basaltic magma of the 2005-eruption was produced from hot rind of the diapir and feebly hydrous basaltic andesite magma of the 2006-eruption was formed from cool and wet core of the diapir.

  6. Tutorial on Reed-Solomon error correction coding

    NASA Technical Reports Server (NTRS)

    Geisel, William A.

    1990-01-01

    This tutorial attempts to provide a frank, step-by-step approach to Reed-Solomon (RS) error correction coding. RS encoding and RS decoding both with and without erasing code symbols are emphasized. There is no need to present rigorous proofs and extreme mathematical detail. Rather, the simple concepts of groups and fields, specifically Galois fields, are presented with a minimum of complexity. Before RS codes are presented, other block codes are presented as a technical introduction into coding. A primitive (15, 9) RS coding example is then completely developed from start to finish, demonstrating the encoding and decoding calculations and a derivation of the famous error-locator polynomial. The objective is to present practical information about Reed-Solomon coding in a manner such that it can be easily understood.

  7. A burst-correcting algorithm for Reed Solomon codes

    NASA Technical Reports Server (NTRS)

    Chen, J.; Owsley, P.

    1990-01-01

    The Bose, Chaudhuri, and Hocquenghem (BCH) codes form a large class of powerful error-correcting cyclic codes. Among the non-binary BCH codes, the most important subclass is the Reed Solomon (RS) codes. Reed Solomon codes have the ability to correct random and burst errors. It is well known that an (n,k) RS code can correct up to (n-k)/2 random errors. When burst errors are involved, the error correcting ability of the RS code can be increased beyond (n-k)/2. It has previously been show that RS codes can reliably correct burst errors of length greater than (n-k)/2. In this paper, a new decoding algorithm is given which can also correct a burst error of length greater than (n-k)/2.

  8. VLSI architecture for a Reed-Solomon decoder

    NASA Technical Reports Server (NTRS)

    Hsu, In-Shek (Inventor); Truong, Trieu-Kie (Inventor)

    1992-01-01

    A basic single-chip building block for a Reed-Solomon (RS) decoder system is partitioned into a plurality of sections, the first of which consists of a plurality of syndrome subcells each of which contains identical standard-basis finite-field multipliers that are programmable between 10 and 8 bit operation. A desired number of basic building blocks may be assembled to provide a RS decoder of any syndrome subcell size that is programmable between 10 and 8 bit operation.

  9. Water Mass Modification through Mixing in the Solomon Sea

    NASA Astrophysics Data System (ADS)

    Alberty, Marion; MacKinnon, Jennifer; Sprintall, Janet

    2015-04-01

    The Solomon Sea is a semi-enclosed sea located in the Equatorial southwest Pacific. With its complex topography and strong channel flow, the Solomon Sea has the potential to strongly mix water masses consisting of Antarctic Intermediate Water and South Pacific Subtropical Mode Water traveling equatorward to join the Equatorial Undercurrent. Observations of temperature and salinity relationships from the primary entry and exit points of the Solomon Sea circulation display erosion of the transported water masses and relaxation of the temperature-salinity gradients. In addition the surface signature in the northeast channels indicate the presence of a different water mass implying recirculation and variability in the surface transport which is consistent with model simulations of the region. The spatial and temporal variations in mixing through out the sea are investigated using CTD and LADCP profiles taken during two cruises in the Solomon Sea. Turbulent diffusivity is estimated by two fine scale parameterization methods. The first method takes advantage of an empirical ratio of Thorpe to Ozmidov length scales below the mixed layer and estimates diffusivity from overturn length and local stratification. This method employs data from the CTD at 1 m resolution. The second method uses shear derived from LADCP data and compares the variance of the spectra to that of the canonical Garrett-Munk model. The same is done with strain variance from CTD estimated buoyancy profiles and the ratio of the shear to strain variance is estimated for the region. Further estimates of mixing are derived from ARGO profiles, utilizing the region's ratio of shear to strain variance derived from the shipboard profiles. The spatial patterns display enhanced mixing near abrupt topographic features and in channels where vertical shear is strongest. Mixing in the thermocline layer is enhanced during the first cruise, which was concurrent with strong regional monsoonal wind forcing.

  10. A VLSI design of a pipeline Reed-Solomon decoder

    NASA Technical Reports Server (NTRS)

    Shao, H. M.; Truong, T. K.; Deutsch, L. J.; Yuen, J. H.; Reed, I. S.

    1985-01-01

    A pipeline structure of a transform decoder similar to a systolic array was developed to decode Reed-Solomon (RS) codes. An important ingredient of this design is a modified Euclidean algorithm for computing the error locator polynomial. The computation of inverse field elements is completely avoided in this modification of Euclid's algorithm. The new decoder is regular and simple, and naturally suitable for VLSI implementation.

  11. Single-Chip VLSI Reed-Solomon Encoder

    NASA Technical Reports Server (NTRS)

    Truong, T. K.; Deutsch, L. J.; Reed, I. S.

    1986-01-01

    Reed-Solomon (RS) encoder based on Berlekamp bit-serial multiplier algorithm. RS code standard, based on code words of 255 8-bit symbols, of which 223 symbols convey information and remaining 32 are check symbols. This code enables correction of up to 16 erroneous information symbols per word. Berlekamp algorithm based on code-generating polynomial with 32 roots that occur in reciprocal pairs. Choice of algorithm permits compact design.

  12. Study of Reed-Solomon correction for mass memory

    NASA Astrophysics Data System (ADS)

    Newman, B.; Hutton, S. J.

    1992-03-01

    Logica has performed a study of Reed-Solomon coding in the context of protecting a mass memory in the harsh space environment, e.g., against galactic cosmic rays and heavy ion rich solar flares. The study examined the relation between the final bit error rate, the rate at which the code is used to scrub errors from the memory, and the rate at which errors occur. The RS(255,252) code was considered.

  13. Fast transforms for decoding Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Reed, I. S.; Huang, J. P.; Truong, T. K.; Miller, R. L.

    1981-01-01

    In the paper it is shown that the Chinese remainder theorem when coupled with a modification of Winograd's method can be used to compute Fourier-like transforms over GF (s super m), where m = 2, 3, . . . , 8. These new transform techniques are to decode Reed-Solomon codes of block length 2 super m -1. The results are shown to be more efficient than the more conventional method.

  14. Geology and petrology of Mahukona Volcano, Hawaii

    USGS Publications Warehouse

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

    1991-01-01

    The submarine Mahukona Volcano, west of the island of Hawaii, is located on the Loa loci line between Kahoolawe and Hualalai Volcanoes. The west rift zone ridge of the volcano extends across a drowned coral reef at about-1150 m and a major slope break at about-1340 m, both of which represent former shoreines. The summit of the volcano apparently reached to about 250 m above sea level (now at-1100 m depth) did was surmounted by a roughly circular caldera. A econd rift zone probably extended toward the east or sutheast, but is completely covered by younger lavas from the adjacent subaerial volcanoes. Samples were vecovered from nine dredges and four submersible lives. Using subsidence rates and the compositions of flows which drape the dated shoreline terraces, we infer that the voluminous phase of tholeiitic shield growth ended about 470 ka, but tholeiitic eruptions continued until at least 435 ka. Basalt, transitional between tholeiitic and alkalic basalt, erupted at the end of tholeiitic volcanism, but no postshield-alkalic stage volcanism occurred. The summit of the volcano apparently subcided below sea level between 435 and 365 ka. The tholeiitic lavas recovered are compositionally diverse. ?? 1991 Springer-Verlag.

  15. The New York Stem Cell Foundation. Interview with Susan Solomon.

    PubMed

    Solomon, Susan

    2012-11-01

    We caught up with Susan Solomon, Co-Founder of The New York Stem Cell Foundation, to discuss the role of the Foundation in facilitating some of the top advances in stem cell science in recent years. Susan L Solomon is Chief Executive Officer and Co-Founder of The New York Stem Cell Foundation (NYSCF), a nonprofit organization established in 2005 to accelerate cures through stem cell research. A longtime healthcare advocate, Susan is a founding member and current President of New Yorkers for the Advancement of Medical Research, is on the Executive Committee for the Alliance for Regenerative Medicine, and she has been a member of the Board of Directors of the Juvenile Diabetes Research Foundation, New York Chapter. Susan was also a member of the Strategic Planning Committee of the Empire State Stem Cell Board. In March 2008, Susan received a New York State Women of Excellence Award from the Governor of New York. In September 2008, she received the Triumph Award from the Brooke Ellison Foundation for her work in establishing NYSCF. Prior to founding NYSCF, Susan, an attorney, spent much of her career building businesses. She established and ran Solomon Partners LLC to provide strategic management consulting to corporations, cultural institutions, foundations and nonprofit organizations. She has also held executive positions at MacAndrews and Forbes Holdings and MMG Patricof and Co. She was the founding Chief Executive Officer of Sothebys.com and was President of Sony Worldwide Networks. PMID:23210823

  16. The origin of the Hawaiian Volcano Observatory

    SciTech Connect

    Dvorak, John

    2011-05-15

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

  17. 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....

  18. Revealing magma degassing below closed-conduit active volcanoes: Geochemical features of volcanic rocks versus fumarolic fluids at Vulcano (Aeolian Islands, Italy)

    NASA Astrophysics Data System (ADS)

    Mandarano, Michela; Paonita, Antonio; Martelli, Mauro; Viccaro, Marco; Nicotra, Eugenio; Millar, Ian L.

    2016-04-01

    The elemental and isotopic compositions of noble gases (He, Ne, and Ar) in olivine- and clinopyroxene-hosted fluid inclusions have been measured for rocks at various degrees of evolution and belonging to high-K calcalkaline-shoshonitic and shoshonitic-potassic series in order to cover the entire volcanological history of Vulcano Island (Italy). The major- and trace-element concentrations and the Sr- and Pb-isotope compositions for whole rocks were integrated with data obtained from the fluid inclusions. 3He/4He in fluid inclusions is within the range of 3.30 and 5.94 R/Ra, being lower than the theoretical value for the deep magmatic source expected for Vulcano Island (6.0-6.2 R/Ra). 3He/4He of the magmatic source is almost constant throughout the volcanic history of Vulcano. Integration of the He- and Sr-isotope systematics leads to the conclusion that a decrease in the He-isotope ratio of the rocks is mainly due to the assimilation of 10-25% of a crustal component similar to the Calabrian basement. 3He/4He shows a negative correlation with Sr isotopes except for the last-erupted Vulcanello latites (Punta del Roveto), which have anomalously high He isotope ratios. This anomaly has been attributed to a flushing process by fluids coming from the deepest reservoirs, since an input of deep magmatic volatiles with high 3He/4He values increases the He-isotope ratio without changing 87Sr/86Sr. A comparison of the He-isotope ratios between fluid inclusions and fumarolic gases shows that only the basalts of La Sommata and the latites of Vulcanello have comparable values. Taking into account that the latites of Vulcanello relate to one of the most-recent eruptions at Vulcano (in the 17th century), we infer that the most probable magma which actually feeds the fumarolic emissions is a latitic body that ponded at about 3-3.5 km of depth and is flushed by fluids coming from a deeper and basic magma.

  19. Sumisu Volcano, Izu-Bonin Arc, Japan: Site of a Rhyolitic Caldera-Forming Eruption From a Small Open-Ocean Island

    NASA Astrophysics Data System (ADS)

    Fiske, R. S.; Tani, K.; Tamura, Y.; Naka, J.; Shukuno, H.; Kido, Y.

    2005-12-01

    Sumisu submarine caldera, an 8 x 10 km Crater Lake type structure along the front of the Izu-Bonin arc, was the site of a 30-60 ka eruption that introduced 50-70 km3 of rhyolite tephra into open-ocean environment. A manned submersible, two ROVs, a DeepTow camera system, and dredge samples (augmented by newly acquired single-channel seismic profiles and SeaBeam mapping) were used to study the caldera and surrounding areas. Caldera-wall studies show that pre-caldera eruptions built a complex of overlapping submarine dacitic and basaltic cones that formed an edifice 40 x 25 km in diameter; its summit grew above sea level to form an island about 200 m high. The caldera-forming eruption likely began on this island and sent a Plinian column high into the air. We interpret that prodigious rates of tephra fallback overwhelmed the Sumisu area, forming huge rafts of floating pumice and forcing large volumes of hot, proximal fallback debris beneath sea level-- generating gravity flows of quenched pumice that traveled downslope along the sea floor. The caldera rim, currently 100-400 m below sea level, is mantled by thin and discontinuous deposits of syn-caldera pumice showing no evidence of heat retention. Ocean currents apparently eroded most proximal pumice away (especially during periods of late Pleistocene sea-level lowering), and the caldera rim is locally mantled by lag lithics. ODP Leg 126 cores in the Sumisu Rift, atop the Rift's east margin, and on the forearc slope, show the sea floor south and southeast to be underlain by non-welded pumice deposits 10-20 m thick. Geochemical data point to Sumisu as the source of these distal deposits, rather than the nearby arc-front centers of Minami Sumisu or Torishima-indicating that the Sumisu pumice gravity flows traveled for distances of at least 70 km. Post-caldera edifice instability resulted in the collapse of a 15 degree sector of the east caldera rim and the formation of spectacular thin-skin slumps that ring much of the edifice.

  20. Volcano Vents

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 5 May 2003

    This low-relief shield volcano imaged with the THEMIS visible camera has two large vents which have erupted several individual lava flows. The positions of the origins of many of the flows indicate that it is probable that the vents are secondary structures that formed only after the shield was built up by eruptions from a central caldera.

    Image information: VIS instrument. Latitude 17.6, Longitude 243.6 East (116.4 West). 19 meter/pixel resolution.

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

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

  1. 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)

  2. 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....

  3. Volcaniclastic debris flows at La Fossa Volcano (Vulcano Island, southern Italy): Insights for erosion behaviour of loose pyroclastic material on steep slopes

    NASA Astrophysics Data System (ADS)

    Ferrucci, M.; Pertusati, S.; Sulpizio, R.; Zanchetta, G.; Pareschi, M. T.; Santacroce, R.

    2005-07-01

    This paper describes a qualitative model of erosion of loose volcaniclastic material on steep slopes of La Fossa cone (Vulcano Island, Italy) that generates small volume debris flows. The loose volcaniclastic cover rests on an almost impermeable substratum, which comprises a fine-grained hydromagmatic tuff. Morphologically, three sectors were distinguished: 1) a water supply zone (slope > 32) where rain water is enriched in mud and concentrated in the initiation zone; 2) an initiation zone (or source area sensu stricto slope with 30) where debris flows form and; 3) a transport and deposition zone where debris flows deposited levees and terminal lobes (slope 30). Main episodes of erosion of loose volcaniclastic cover and debris flow generation occur in response to thunderstorms. The erosion of tuff from superficial water added a significant amount of fines (mud fraction) to the initiating flows. Debris flow stoppage on steep slopes was interpreted as the result of a loss of mass (estimated between 35% and 53% of total mass) to form levees. From field and laboratory data the density of debris flows was estimated at about 1950 kg/m 3. Morphological data, matrix texture, mass number ( Nm) and clay content of debris flow deposits suggest that they were deposited by saturated granular slurries.

  4. 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/.

  5. 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.

  6. Exploring New Challenges of High-Resolution SWOT Satellite Altimetry with a Regional Model of the Solomon Sea

    NASA Astrophysics Data System (ADS)

    Brasseur, P.; Verron, J. A.; Djath, B.; Duran, M.; Gaultier, L.; Gourdeau, L.; Melet, A.; Molines, J. M.; Ubelmann, C.

    2014-12-01

    The upcoming high-resolution SWOT altimetry satellite will provide an unprecedented description of the ocean dynamic topography for studying sub- and meso-scale processes in the ocean. But there is still much uncertainty on the signal that will be observed. There are many scientific questions that are unresolved about the observability of altimetry at vhigh resolution and on the dynamical role of the ocean meso- and submesoscales. In addition, SWOT data will raise specific problems due to the size of the data flows. These issues will probably impact the data assimilation approaches for future scientific or operational oceanography applications. In this work, we propose to use a high-resolution numerical model of the Western Pacific Solomon Sea as a regional laboratory to explore such observability and dynamical issues, as well as new data assimilation challenges raised by SWOT. The Solomon Sea connects subtropical water masses to the equatorial ones through the low latitude western boundary currents and could potentially modulate the tropical Pacific climate. In the South Western Pacific, the Solomon Sea exhibits very intense eddy kinetic energy levels, while relatively little is known about the mesoscale and submesoscale activities in this region. The complex bathymetry of the region, complicated by the presence of narrow straits and numerous islands, raises specific challenges. So far, a Solomon sea model configuration has been set up at 1/36 resolution. Numerical simulations have been performed to explore the meso- and submesoscales dynamics. The numerical solutions which have been validated against available in situ data, show the development of small scale features, eddies, fronts and filaments. Spectral analysis reveals a behavior that is consistent with the SQG theory. There is a clear evidence of energy cascade from the small scales including the submesoscales, although those submesoscales are only partially resolved by the model. In parallel, investigations have been conducted using image assimilation approaches in order to explore the richness of high-resolution altimetry missions. These investigations illustrate the potential benefit of combining tracer fields (SST, SSS and spiciness) with high-resolution SWOT data to estimate the fine-scale circulation.

  7. 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.

  8. Glaciation of Haleakala volcano, Hawaii

    SciTech Connect

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

    1993-04-01

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

  9. 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.

  10. The Anatahan volcano-monitoring system

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    A real-time 24/7 Anatahan volcano-monitoring and eruption detection system is now operational. There had been no real-time seismic monitoring on Anatahan during the May 10, 2003 eruption because the single telemetered seismic station on Anatahan Island had failed. On May 25, staff from the Emergency Management Office (EMO) of the Commonwealth of the Northern Mariana Islands and the U. S. Geological Survey (USGS) established a replacement telemetered seismic station on Anatahan whose data were recorded on a drum recorder at the EMO on Saipan, 130 km to the south by June 5. In late June EMO and USGS staff installed a Glowworm seismic data acquisition system (Marso et al, 2003) at EMO and hardened the Anatahan telemetry links. The Glowworm system collects the telemetered seismic data from Anatahan and Saipan, places graphical display products on a webpage, and exports the seismic waveform data in real time to Glowworm systems at Hawaii Volcano Observatory and Cascades Volcano Observatory (CVO). In early July, a back-up telemetered seismic station was placed on Sarigan Island 40 km north of Anatahan, transmitting directly to the EMO on Saipan. Because there is currently no population on the island, at this time the principal hazard presented by Anatahan volcano would be air traffic disruption caused by possible erupted ash. The aircraft/ash hazard requires a monitoring program that focuses on eruption detection. The USGS currently provides 24/7 monitoring of Anatahan with a rotational seismic duty officer who carries a Pocket PC-cell phone combination that receives SMS text messages from the CVO Glowworm system when it detects large seismic signals. Upon receiving an SMS text message notification from the CVO Glowworm, the seismic duty officer can use the Pocket PC - cell phone to view a graphic of the seismic traces on the EMO Glowworm's webpage to determine if the seismic signal is eruption related. There have been no further eruptions since the monitoring system was installed, but regional tectonic earthquakes have provided frequent tests of the system. Reliance on a Pocket PC - cell phone requires that the seismic duty officer remain in an area with cell phone coverage. With this monitoring method, the USGS is able to provide rapid notice of an Anatahan eruption to the EMO and the Washington Volcano Ash Advisory Center. Reference Marso, J.N., Murray, T.L., Lockhart, A.B., Bryan, C.J., Glowworm: An extended PC-based Earthworm system for volcano monitoring. Abstracts, Cities On Volcanoes III, Hilo Hawaii, July 2003.

  11. 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.

  12. 75 FR 57388 - Special Local Regulations for Marine Events; Patuxent River, Solomons, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... Marine Events; Patuxent River, Solomons, MD'' in the Federal Register (75 FR 32866). Additionally, on... Local Regulations for Marine Events; Patuxent River, Solomons, MD'' in the Federal Register (75 FR 41789.... These special local regulations are necessary to provide for the safety of life on navigable...

  13. 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.

  14. Volcanoes: Nature's Caldrons Challenge Geochemists.

    ERIC Educational Resources Information Center

    Zurer, Pamela S.

    1984-01-01

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

  15. 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.

  16. Binary weight distributions of some Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Pollara, F.; Arnold, S.

    1992-01-01

    The binary weight distributions of the (7,5) and (15,9) Reed-Solomon (RS) codes and their duals are computed using the MacWilliams identities. Several mappings of symbols to bits are considered and those offering the largest binary minimum distance are found. These results are then used to compute bounds on the soft-decoding performance of these codes in the presence of additive Gaussian noise. These bounds are useful for finding large binary block codes with good performance and for verifying the performance obtained by specific soft-coding algorithms presently under development.

  17. The Reed-Solomon encoders: Conventional versus Berlekamp's architecture

    NASA Technical Reports Server (NTRS)

    Perlman, M.; Lee, J. J.

    1982-01-01

    Concatenated coding was adopted for interplanetary space missions. Concatenated coding was employed with a convolutional inner code and a Reed-Solomon (RS) outer code for spacecraft telemetry. Conventional RS encoders are compared with those that incorporate two architectural features which approximately halve the number of multiplications of a set of fixed arguments by any RS codeword symbol. The fixed arguments and the RS symbols are taken from a nonbinary finite field. Each set of multiplications is bit-serially performed and completed during one (bit-serial) symbol shift. All firmware employed by conventional RS encoders is eliminated.

  18. Space Radar Image of Teide Volcano

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image shows the Teide volcano on the island of Tenerife in the Canary Islands. The Canary Islands, part of Spain, are located in the eastern Atlantic Ocean off the coast of Morocco. Teide has erupted only once in the 20th Century, in 1909, but is considered a potentially threatening volcano due to its proximity to the city of Santa Cruz de Tenerife, shown in this image as the purple and white area on the lower right edge of the island. The summit crater of Teide, clearly visible in the left center of the image, contains lava flows of various ages and roughnesses that appear in shades of green and brown. Different vegetation zones, both natural and agricultural, are detected by the radar as areas of purple, green and yellow on the volcano's flanks. Scientists are using images such as this to understand the evolution of the structure of Teide, especially the formation of the summit caldera and the potential for collapse of the flanks. The volcano is one of 15 identified by scientists as potentially hazardous to local populations, as part of the international The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 11, 1994. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth. The image is centered at 28.3 degrees North latitude and 16.6 degrees West longitude. North is toward the upper right. The area shown measures 90 kilometers by 54.5 kilometers (55.8 miles by 33.8 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is C-band horizontally transmitted, vertically received.

  19. The Volcano Adventure Guide

    NASA Astrophysics Data System (ADS)

    Goff, Fraser

    2005-05-01

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

  20. 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.

  1. Reed-Solomon Codes and the Deep Hole Problem

    NASA Astrophysics Data System (ADS)

    Keti, Matt

    In many types of modern communication, a message is transmitted over a noisy medium. When this is done, there is a chance that the message will be corrupted. An error-correcting code adds redundant information to the message which allows the receiver to detect and correct errors accrued during the transmission. We will study the famous Reed-Solomon code (found in QR codes, compact discs, deep space probes,ldots) and investigate the limits of its error-correcting capacity. It can be shown that understanding this is related to understanding the "deep hole" problem, which is a question of determining when a received message has, in a sense, incurred the worst possible corruption. We partially resolve this in its traditional context, when the code is based on the finite field F q or Fq*, as well as new contexts, when it is based on a subgroup of F q* or the image of a Dickson polynomial. This is a new and important problem that could give insight on the true error-correcting potential of the Reed-Solomon code.

  2. Iceland's Grmsvtn volcano erupts

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-05-01

    About 13 months after Iceland's Eyjafjallajkull volcano began erupting on 14 April 2010, which led to extensive air traffic closures over Europe, Grmsvtn volcano in southeastern took its turn. Iceland's most active volcano, which last erupted in 2004 and lies largely beneath the Vatnajkull 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 Grmsvtn 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.

  3. Mud volcanoes on Mars?

    NASA Technical Reports Server (NTRS)

    Komar, Paul D.

    1991-01-01

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

  4. 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 δ18O 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.

  5. 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....

  6. Airborne gravity reveals interior of Antarctic volcano

    NASA Astrophysics Data System (ADS)

    Jordan, T. A.; Ferraccioli, F.; Jones, P. C.; Smellie, J. L.; Ghidella, M.; Corr, H.

    2009-07-01

    Understanding Antarctic volcanoes is important as they provide a window on magmatic and tectonic processes of the Antarctic plate and contain datable records of ice-sheet changes. We present the results from the first detailed airborne radar and gravity surveys across James Ross Island, northern Antarctic Peninsula, which is dominated by Mt Haddington, an ice-covered Miocene-Recent alkaline stratovolcano. The surveys provide new insights into the subsurface structure of the volcano and hence its development, which are unavailable from the surface geology alone. We show that Mt Haddington is associated with a significant negative Bouguer gravity anomaly (≥26 mGal), which suggests that there has not been significant pooling and solidification of a dense shallow-level mafic magma chamber during the growth of the volcano over at least the past 6 m.y., which is consistent with independent geochemical evidence. Simple flexural isostatic models cannot explain the localised negative Bouguer anomaly. 3D modelling techniques show that the negative anomaly is best explained by a shallow, low-density intra-crustal body with its top close to, or at, the surface. Although comparable gravity anomalies are commonly associated with large (˜20 km) ash-filled calderas, as seen at Yellowstone or Toba, there is no geological evidence on James Ross Island for a similar structure. We therefore propose that the James Ross Island volcanic edifice subsided into the thick underlying pile of relatively soft Jurassic and Cretaceous sediments, which were displaced by low-density hyaloclastite breccia. The type of deformation envisaged is similar to that associated with Concepcioú, or Iwaki volcanoes in South America, although Mt Haddington is much larger.

  7. Space communication system for compressed data with a concatenated Reed-Solomon-Viterbi coding channel

    NASA Technical Reports Server (NTRS)

    Rice, R. F.; Hilbert, E. E. (inventors)

    1976-01-01

    A space communication system incorporating a concatenated Reed Solomon Viterbi coding channel is discussed for transmitting compressed and uncompressed data from a spacecraft to a data processing center on Earth. Imaging (and other) data are first compressed into source blocks which are then coded by a Reed Solomon coder and interleaver, followed by a convolutional encoder. The received data is first decoded by a Viterbi decoder, followed by a Reed Solomon decoder and deinterleaver. The output of the latter is then decompressed, based on the compression criteria used in compressing the data in the spacecraft. The decompressed data is processed to reconstruct an approximation of the original data-producing condition or images.

  8. 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.

  9. Small Dusty Volcano

    NASA Technical Reports Server (NTRS)

    2005-01-01

    3 July 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small, dust-covered, volcano in the Jovis Fossae region of Mars. While Mars is known for its extremely large volcanoes, such as Olympus Mons, many small volcanoes also occur on the red planet, particularly in the Tharsis region. This small volcano is a good example of those. It was originally found by members of the MGS Mars Orbiter Laser Altimeter (MOLA) team during the MGS primary mission. The volcano is old, and cratered. Its surface is mantled by dust, and its caldera (summit depression) has some dust-covered wind ripples on its floor.

    Location near: 20.7oN, 111.3oW Image width: 3 km (1.9 mi) Illumination from: lower left Season Northern Autumn

  10. A decoding procedure for the Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Lim, R. S.

    1978-01-01

    A decoding procedure is described for the (n,k) t-error-correcting Reed-Solomon (RS) code, and an implementation of the (31,15) RS code for the I4-TENEX central system. This code can be used for error correction in large archival memory systems. The principal features of the decoder are a Galois field arithmetic unit implemented by microprogramming a microprocessor, and syndrome calculation by using the g(x) encoding shift register. Complete decoding of the (31,15) code is expected to take less than 500 microsecs. The syndrome calculation is performed by hardware using the encoding shift register and a modified Chien search. The error location polynomial is computed by using Lin's table, which is an interpretation of Berlekamp's iterative algorithm. The error location numbers are calculated by using the Chien search. Finally, the error values are computed by using Forney's method.

  11. Solomon M. Hsiang Receives 2013 Science for Solutions Award: Citation

    NASA Astrophysics Data System (ADS)

    Oppenheimer, Michael

    2014-01-01

    Solomon Hsiang is representative of a new generation in the geosciences community, whose work spans several disciplines, drawing on methods and concepts from far outside the traditional physical science domain in order to make progress on difficult questions at the intersection of natural science, social science, and public policy. Broadly speaking, by examining how humanity has responded to climate variability and change in the distant and recent past, Sol's research elucidates the question of how humanity may respond to a changing climate in the future. Combining large, independent sets of social science, meteorological, and climatological data and analyzing them with tools more common in microeconomics than natural science, Sol, still at an early stage of his career, has made critical contributions to an incipient revolution in our understanding of the sensitivity and adaptability of humans and their social arrangements to climate variability and change. Such insights will greatly improve the information base from which effective public policy is developed.

  12. Transport of Fine Ash Through the Water Column at Erupting Volcanoes - Monowai Cone, Kermadec-Tonga Arc

    NASA Astrophysics Data System (ADS)

    Walker, S. L.; Baker, E. T.; Leybourne, M. I.; de Ronde, C. E.; Greene, R.; Faure, K.; Chadwick, W.; Dziak, R. P.; Lupton, J. E.; Lebon, G.

    2010-12-01

    Monowai cone is a large, active, basaltic stratovolcano, part of the submarine Monowai volcanic center (MVC) located at ~26S on the Kermadec-Tonga arc. At other actively erupting submarine volcanoes, magma extrusions and hydrothermal vents have been located only near the summit of the edifice, generating plumes enriched with hydrothermal components and magmatic gasses that disperse into the ocean environment at, or shallower than, the summit depth. Plumes found deeper than summit depths are dominated by fresh volcaniclastic ash particles, devoid of hydrothermal tracers, emplaced episodically by down-slope gravity flows, and transport fine ash to 10s of km from the active eruptions. A water column survey of the MVC in 2004 mapped intensely hydrothermal-magmatic plumes over the shallow (~130 m) summit of Monowai cone and widespread plumes around its flanks. Due to the more complex multiple parasitic cone and caldera structure of MVC, we analyzed the dissolved and particulate components of the flank plumes for evidence of additional sources. Although hydrothermal plumes exist within the adjacent caldera, none of the parasitic cones on Monowai cone or elsewhere within the MVC were hydrothermally or volcanically active. The combination of an intensely enriched summit plume, sulfur particles and bubbles at the sea surface, and ash-dominated flank plumes indicate Monowai cone was actively erupting at the time of the 2004 survey. Monowai cone is thus the fourth erupting submarine volcano we have encountered, and all have had deep ash plumes distributed around their flanks [the others are: Kavachi (Solomon Island arc), NW Rota-1 (Mariana arc) and W Mata (NE Lau basin)]. These deep ash plumes are a syneruptive phenomenon, but it is unknown how they are related to eruptive style and output, or to the cycles of construction and collapse that occur on the slopes of submarine volcanoes. Repeat multibeam bathymetric surveys have documented two large-scale sector collapse events at Monowai and one at NW Rota-1, as well as constructional deposits extending down the flanks of these volcanoes. Acoustic records at Monowai and NW Rota-1 suggest sector collapse events are infrequent while eruptions, and the resulting supply of depositional material, have been nearly continuous. The sector collapse events occurred at times remote from our plume surveys, so, large landslide events are not a prerequisite for the presence of deep ash plumes. Despite a wide range of summit depths (<10 m at Kavachi to 1500 m at W Mata), lava types (basaltic-andesite, boninite, and basalt), and eruptive styles (Surtseyan, Strombolian, and effusive flows with active pillow formation), the deep particle plumes at each of these volcanoes are remarkably similar in their widespread distribution (to 10s of km from the summit and at multiple depths down the flanks) and composition (dominantly fresh volcanic ash). Moderate eruption rates, lava-seawater interaction and steep slopes below an eruptive vent may be sufficient to initiate the transport of fine ash into the ocean environment and distal sediments via these types of plumes.

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

    USGS Publications Warehouse

    Duffield, Wendell A.

    2003-01-01

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

  14. Bathymetry of southern Mauna Loa Volcano, Hawaii

    USGS Publications Warehouse

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

    1993-01-01

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

  15. The VLSI design of a single chip Reed-Solomon encoder

    NASA Technical Reports Server (NTRS)

    Truong, T. K.; Deutsch, L. J.; Reed, I. S.

    1982-01-01

    A design for a single chip implementation of a Reed-Solomon encoder is presented. The architecture that leads to this single VLSI chip design makes use of a bit serial finite field multiplication algorithm.

  16. Circles: Mother and Daughter Relationships in Toni Morrison's "Song of Solomon."

    ERIC Educational Resources Information Center

    Subryan, Carmen

    1988-01-01

    Examines the mother daughter relationships portrayed in Toni Morrison's novel, "Song of Solomon." Shows how societal influences can result in the stagnation of Black womens' spirits, and how love and compassion can result in the uplifting of the spirit. (FMW)

  17. "What Shalimar Knew": Toni Morrison's "Song of Solomon" as a Pastoral Novel.

    ERIC Educational Resources Information Center

    Imbrie, Ann E.

    1993-01-01

    Explains the biblical reference in the title of Toni Morrison's novel, "Song of Solomon," as pointing to the book's form and political implications. Connects the title with the traditional pastoral mode and analyzes the novel as pastoral. (HB)

  18. Mauna Iki and the Kaju Desert: Kilauea Volcano, Hawaii

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.

    1974-01-01

    The Ka'u Desert lies southwest of Kilauea Volcano. The region contains some of the most interesting and best preserved volcanic features found in the islands. The structural setting and synopsis of recent volcanic activity on the Ka'u Desert are discussed here, and a field guide to Mauna Iki is provided.

  19. Mauna Loa--history, hazards and risk of living with the world's largest volcano

    USGS Publications Warehouse

    Trusdell, Frank A.

    2012-01-01

    Mauna Loa on the Island Hawai?i is the worlds largest volcano. People residing on its flanks face many hazards that come with living on or near an active volcano, including lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and local tsunami (giant seawaves). The County of Hawai?i (Island of Hawai?i) is the fastest growing County in the State of Hawaii. Its expanding population and increasing development mean that risk from volcano hazards will continue to grow. U.S. Geological Survey (USGS) scientists at the Hawaiian Volcano Observatory (HVO) closely monitor and study Mauna Loa Volcano to enable timely warning of hazardous activity and help protect lives and property.

  20. 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 islands 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.

  1. Volcanoes. A planetary perspective.

    NASA Astrophysics Data System (ADS)

    Francis, P.

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

  2. Reed-Solomon error-correction as a software patch mechanism.

    SciTech Connect

    Pendley, Kevin D.

    2013-11-01

    This report explores how error-correction data generated by a Reed-Solomon code may be used as a mechanism to apply changes to an existing installed codebase. Using the Reed-Solomon code to generate error-correction data for a changed or updated codebase will allow the error-correction data to be applied to an existing codebase to both validate and introduce changes or updates from some upstream source to the existing installed codebase.

  3. Solomon Sea circulation and water mass modifications: response at ENSO timescales

    NASA Astrophysics Data System (ADS)

    Melet, Anglique; Gourdeau, Lionel; Verron, Jacques; Djath, Bughsin

    2013-01-01

    The South Pacific low latitude western boundary currents (LLWBCs) carry waters of subtropical origin through the Solomon Sea before joining the equatorial Pacific. Changes in their properties or transport are assumed to impact El Nio Southern Oscillation (ENSO) dynamics. At ENSO timescales, the LLWBCs transport tends to counterbalance the interior geostrophic one. When transiting through the complex geography of the Solomon Sea, the main LLWBC, the New Guinea Coastal Undercurrent, cannot follow a unique simple route to the equator. Instead, its routes and water mass properties are influenced by the circulation occurring in the Solomon Sea. In this study, the response of the Solomon Sea circulation to ENSO is investigated based on a numerical simulation. The transport anomalies entering the Solomon Sea from the south are confined to the top 250 m of the water column, where they represent 7.5 Sv (based on ENSO composites) for a mean transport of 10 Sv. The induced circulation anomalies in the Solomon Sea are not symmetric between the two ENSO states because of (1) a bathymetric control at Vitiaz Strait, which plays a stronger role during El Nio, and (2) an additional inflow through Solomon Strait during La Nia events. In terms of temperature and salinity, modifications are particularly notable for the thermocline water during El Nio conditions, with cooler and fresher waters compared to the climatological mean. The surface water at Vitiaz Strait and the upper thermocline water at Solomon Strait, feeding respectively the equatorial Pacific warm pool and the Equatorial Undercurrent, particularly affect the heat and salt fluxes. These fluxes can change by up to a factor of 2 between extreme El Nio and La Nia conditions.

  4. Unzen Volcano, Japan

    NASA Technical Reports Server (NTRS)

    1995-01-01

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

    Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI).

  5. Solomon Sea circulation and water mass modifications: response at ENSO time-scales

    NASA Astrophysics Data System (ADS)

    Verron, J. A.; Melet, A. V.; Gourdeau, L.; Djath, N.

    2012-12-01

    The South Pacific low latitude western boundary currents (LLWBCs) carry waters of subtropical origin through the Solomon Sea before joining the equatorial Pacific. Changes in their properties or transport are assumed to impact ENSO dynamics. At ENSO time-scales, the LLWBCs transport tends to counterbalance the interior geostrophic one. However, the Solomon Sea is a strong constraint to the propagation of the LLWBCs. In this study, the response of the Solomon Sea circulation to ENSO is investigated based on a numerical simulation. The transport anomalies entering the Solomon Sea from the south are confined to the top 250 m of the water column, and represent 9 Sv (which is half of the mean transport).The induced circulation anomalies are not symmetric between the two ENSO states because of (1) a bathymetric control at Vitiaz Strait, that plays a stronger role during El Nio, and (2) an additional inflow at Solomon Strait during La Nia events. In terms of temperature and salinity, modifications are particularly notable for the thermocline water during El Nio conditions, with cooler and fresher waters compared to a climatological mean. The surface water at Vitiaz Strait and the upper thermocline water at Solomon Strait, feeding respectively the equatorial Pacific warm pool and the Equatorial Undercurrent, particularly affect the heat and salt fluxes. These fluxes can change by up to a factor of 2 between El Nio and La Nia conditions.

  6. Shaking up volcanoes

    USGS Publications Warehouse

    Prejean, Stephanie G.; Haney, Matthew M.

    2014-01-01

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

  7. Vent of Sand Volcano

    USGS Multimedia Gallery

    Vent of sand volcano produced by liquefaction is about 4 ft across in strawberry field near Watsonville. Strip spanning vent is conduit for drip irrigation system. Furrow spacing is about 1.2 m (4 ft) on center....

  8. Jun Jaegyu Volcano: A Recently Discovered Alkali Basalt Volcano in Antarctic Sound, Antarctica

    NASA Astrophysics Data System (ADS)

    Hatfield, A.; Bailey, D.; Domack, E.; Brachfeld, S.; Gilbert, R.; Ishman, S.; Krahmann, G.; Leventer, A.

    2004-12-01

    Jun Jaegyu is a young volcanic construct discovered in May 2004 by researchers aboard the National Science Foundation (NSF) vessel Laurence M. Gould (LMG04-04). The volcano is located on the Antarctic continental shelf in Antarctic Sound, approximately 9 km due north of the easternmost point of Andersson Island. Swath bathymetry (NBP01-07) indicates that the volcano stands 700 meters above the seafloor, yet remains 275 meters short of the ocean surface. The seamount lies along a northwest-southeast oriented fault scarp and contains at least 1.5 km3 of volcanic rock. Video recording of the volcano's surface revealed regions nearly devoid of submarine life. These areas are associated with a thermal anomaly of up to 0.052 C higher than the surrounding ocean water. A rock dredge collected ~13 kg of material, over 80% of which was fresh volcanic rock; the remainder was glacial IRD. These observations, along with reports by mariners of discolored water in this region of Antarctic Sound, suggest that the volcano has been recently active. The basalt samples are generally angular, glassy and vesicular. Preliminary petrographic observations indicate that plagioclase, olivine, and clinopyroxene are all present as phenocryst phases, and that small (<1cm) rounded xenoliths are common. A comprehensive study of the volcano's petrography and whole-rock chemistry is currently underway. Jun Jaegyu is the northernmost volcanic center of the James Ross Island Volcanic Group (JRIVG), and the only center in this region of the Antarctic Peninsula with evidence of recent activity. It lies along the boundary between the Late Cenozoic JRIVG and the Upper Paleozoic rocks of the Trinity Peninsula Formation. While the tectonic setting of the region is complex, volcanism appears to be associated with active faults related to within-plate extension.

  9. Basaltic island sand provenance

    SciTech Connect

    Marsaglia, K.M. . Dept. of Geological Sciences)

    1992-01-01

    The Hawaiian Islands are an ideal location to study basaltic sand provenance in that they are a series of progressively older basaltic shield volcanoes with arid to humid microclimates. Sixty-two sand samples were collected from beaches on the islands of Hawaii, Maui, Oahu and Kauai and petrographically analyzed. The major sand components are calcareous bioclasts, volcanic lithic fragments, and monomineralic grains of dense minerals and plagioclase. Proportions of these components vary from island to island, with bioclastic end members being more prevalent on older islands exhibiting well-developed fringing reef systems and volcanic end members more prevalent on younger, volcanically active islands. Climatic variations across the island of Hawaii are reflected in the percentage of weathered detritus, which is greater on the wetter, northern side of the island. The groundmass of glassy, basaltic lithics is predominantly black tachylite, with lesser brown sideromelane; microlitic and lathwork textures are more common than holohyaline vitric textures. Other common basaltic volcanic lithic fragments are holocrystalline aggregates of silt-sized pyroxene or olivine, opaque minerals and plagioclase. Sands derived from alkalic lavas are texturally and compositionally indistinguishable from sands derived from tholeiitic lavas. Although Hawaiian basaltic sands overlap in composition with magmatic arc-derived sands in terms of their relative QFL, QmPK and LmLvLs percentages, they are dissimilar in that they lack felsic components and are more enriched in lathwork volcanic lithic fragments, holocrystalline volcanic lithic fragments, and dense minerals.

  10. Near-Surface Circulation in the Solomon Sea Derived from Lagrangian Drifter Observations

    NASA Astrophysics Data System (ADS)

    Hristova, H. G.; Kessler, W. S.

    2010-12-01

    A low-latitude western boundary current in the Solomon Sea in the southwest Pacific Ocean carries waters from the subtropical gyre toward the tropics. Despite its importance as a major pathway connecting the subtropics to the equator, our knowledge about the Solomon Sea circulation remains incomplete and direct observations are sparse. Here, we use the Global Drifter Program (GDP) dataset to map out the near-surface circulation in the vicinity of the Solomon Sea. The analysis is based on pseudo-eulerian statistics computed from nearly 500 satellite-tracked drifting buoys drogued at 15m depth that have transited through the region during the 16-year period from 1994 to 2009. To the east of the Solomon Sea, the seasonally averaged velocity field outlines the changes in intensity and position of the main regional currents - the South Equatorial Current (SEC) and the South Equatorial CounterCurrent (SECC). Within the Solomon Sea, the drifters suggest a surface flow to the northwest that hugs the Papua New Guinea coast and exits equatorward through Vitiaz Strait. The flow is at its maximum during the austral winter, when the southeast monsoon winds are also at their strongest, while it is much weaker and undefined during the austral summer, reversing direction in the southeastern part of the basin at this time. The surface flow in Solomon Strait, the other major opening toward the equator, is to the southwest (into the sea) year around. Consistent with findings from altimetry data, the drifters single out the interior of the Solomon Sea as a region of enhanced eddy kinetic energy. The drifter-derived velocity field is compared with other observational climatologies, such as the CSIRO Atlas of the Regional Seas (CARS).

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

    NASA Astrophysics Data System (ADS)

    Rashidov, Tofig

    2014-05-01

    As the natural phenomenon the mud volcanism (mud volcanoes) of Azerbaijan are known from the ancient times. The historical records describing them are since V century. More detail study of this natural phenomenon had started in the second half of XIX century. The term "mud volcano" (or "mud hill") had been given by academician H.W. Abich (1863), more exactly defining this natural phenomenon. All the previous definitions did not give such clear and capacious explanation of it. In comparison with magmatic volcanoes, globally the mud ones are restricted in distribution; they mainly locate within the Alpine-Himalayan, Pacific and Central Asian mobile belts, in more than 30 countries (Columbia, Trinidad Island, Italy, Romania, Ukraine, Georgia, Azerbaijan, Turkmenistan, Iran, Pakistan, Indonesia, Burma, Malaysia, etc.). Besides it, the zones of mud volcanoes development are corresponded to zones of marine accretionary prisms' development. For example, the South-Caspian depression, Barbados Island, Cascadia (N.America), Costa-Rica, Panama, Japan trench. Onshore it is Indonesia, Japan, and Trinidad, Taiwan. The mud volcanism with non-accretionary conditions includes the areas of Black Sea, Alboran Sea, the Gulf of Mexico (Louisiana coast), Salton Sea. But new investigations reveal more new mud volcanoes and in places which were not considered earlier as the traditional places of mud volcanoes development (e.g. West Nile Rive delta). Azerbaijan is the classic region of mud volcanoes development. From over 800 world mud volcanoes there are about 400 onshore and within the South-Caspian basin, which includes the territory of East Azerbaijan (the regions of Shemakha-Gobustan and Low-Kura River, Absheron peninsula), adjacent water area of South Caspian (Baku and Absheron archipelagoes) and SW Turkmenistan and represents an area of great downwarping with thick (over 25 km) sedimentary series. Generally, in the modern relief the mud volcanoes represent more or less large uplifts on surface, often of plane-conical shape, rising for 5 to 400 m and more over the country (for example, mud volcano Toragay, 400 m height). The base diameter is from 100 m to 3-4 km and more. Like the magmatic ones, the mud volcanoes are crowned with crater of convex-plane or deeply-seated shape. In Azerbaijan there are all types of mud volcanoes: active, extinct, buried, submarine, island, abundantly oil seeping. According to their morphology they are defined into cone-shaped, dome-shaped, ridge-shaped, plateau-shaped. The crater shapes are also various: conical, convex-plane, shield-shaped, deeply-seated, caldera-like. The most complete morphological classification was given in "Atlas of mud volcanoes of Azerbaijan" (Yakubov et al., 1971). Recently (Aliyev Ad. et al., 2003) it was proposed a quite new morphological classification of mud volcanoes of Azerbaijan. For the first time the mud volcanic manifestations had been defined. Volcanoes are ranged according to morphological signs, crater shape and type of activity.

  12. Investigation of the Dashigil mud volcano (Azerbaijan) using beryllium-10

    NASA Astrophysics Data System (ADS)

    Kim, K. J.; Baskaran, M.; Jweda, J.; Feyzullayev, A. A.; Aliyev, C.; Matsuzaki, H.; Jull, A. J. T.

    2013-01-01

    We collected and analyzed five sediments from three mud volcano (MV) vents and six suspended and bottom sediment samples from the adjoining river near the Dashgil mud volcano in Azerbaijan for 10Be. These three MV are found among the 190 onshore and >150 offshore MV in this region which correspond to the western flank of the South Caspian depression. These MVs overlie the faulted and petroleum-bearing anticlines. The 10Be concentrations and 10Be/9Be ratios are comparable to the values reported for mud volcanoes in Trinidad Island. It appears that the stable Be concentrations in Azerbaijan rivers are not perturbed by anthropogenic effects and are comparable to the much older sediments (mud volcano samples). The 10Be and 9Be concentrations in our river sediments are compared to the global data set and show that the 10Be values found for Kura River are among the lowest of any river for which data exist. We attribute this low 10Be concentration to the nature of surface minerals which are affected by the residual hydrocarbon compounds that occur commonly in the study area in particular and Azerbaijan at large. The concentrations of 40K and U-Th-series radionuclides (234Th, 210Pb, 226Ra, and 228Ra) indicate overall homogeneity of the mud volcano samples from the three different sites. Based on the 10Be concentrations of the mud volcano samples, the age of the mud sediments could be at least as old as 4 myr.

  13. Genetic algorithm for TEC seismo-ionospheric anomalies detection around the time of the Solomon (Mw = 8.0) earthquake of 06 February 2013

    NASA Astrophysics Data System (ADS)

    Akhoondzadeh, M.

    2013-08-01

    On 6 February 2013, at 12:12:27 local time (01:12:27 UTC) a seismic event registering Mw 8.0 struck the Solomon Islands, located at the boundaries of the Australian and Pacific tectonic plates. Time series prediction is an important and widely interesting topic in the research of earthquake precursors. This paper describes a new computational intelligence approach to detect the unusual variations of the total electron content (TEC) seismo-ionospheric anomalies induced by the powerful Solomon earthquake using genetic algorithm (GA). The GA detected a considerable number of anomalous occurrences on earthquake day and also 7 and 8 days prior to the earthquake in a period of high geomagnetic activities. In this study, also the detected TEC anomalies using the proposed method are compared to the results dealing with the observed TEC anomalies by applying the mean, median, wavelet, Kalman filter, ARIMA, neural network and support vector machine methods. The accordance in the final results of all eight methods is a convincing indication for the efficiency of the GA method. It indicates that GA can be an appropriate non-parametric tool for anomaly detection in a non linear time series showing the seismo-ionospheric precursors variations.

  14. Volcanoes: Coming Up from Under.

    ERIC Educational Resources Information Center

    Science and Children, 1980

    1980-01-01

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

  15. Camera formation and more, but what comes next? an analysis of volcanic threat of Nisyros island, Greece

    NASA Astrophysics Data System (ADS)

    Winson, A.; Kinvig, H.; Gottsmann, J.; Partington, E.; Geyer, A.

    2008-10-01

    We present an analysis of volcanic threat of Nisyros island (Greece) based on a catalogue of questions compiled for the USGS National Volcano Early Warning System (NVEWS). We find that the score puts Nisyros in the league of volcanoes posing a very high threat. US volcanoes with a comparable threat level include Mt. St. Helens, Augustine and the Long Valley caldera.

  16. Oceanic transports through the Solomon Sea: The bend of the New Guinea Coastal Undercurrent

    NASA Astrophysics Data System (ADS)

    Gasparin, Florent; Ganachaud, Alexandre; Maes, Christophe; Marin, Frdric; Eldin, Grard

    2012-08-01

    Thermocline waters of the tropical southwest Pacific can be traced back to the center of the South Pacific basin and have a potential influence on equatorial surface conditions and on the characteristics of the El Nio Southern Oscillation on decadal timescales. The Solomon Sea is traversed by this influential flow, and therefore is an optimal place for exploring this oceanic connection to the equator. From a high-resolution hydrographic survey at which we applied an inverse box model, we describe the main pathways at the entrance of the Solomon Sea, and more particularly the extremely sharp bend of the western boundary current around the south-east tip of Papua New Guinea. Of the 30 Sv subtropical waters transported into the Coral Sea from the east, above 1300 m, 29 5 Sv makes its way through the Solomon Sea with a large part transported in a boundary current, at the entrance of the Solomon Sea. Around the south-east tip of Papua New Guinea, the Gulf of Papua Current turns abruptly to the north, in a very sharp bend as it merges into the New Guinea Coastal Undercurrent, on its way, toward the equator. The warm currents transport large amounts of internal energy, with a total of 1.0 0.3 1015W entering the Solomon Sea from the south.

  17. Understanding Merapi-type Volcanoes

    NASA Astrophysics Data System (ADS)

    Purbawinata, Mas Atje; Ratdomopurbo, Antonius; Surono, null; Pallister, John; Luehr, Birger; Newhall, Chris

    2007-01-01

    ``We have to understand volcano science to know what to monitor.'' That simple statement by Antonius Ratdomopurbo, director of the Indonesian Center for Volcano Technology [Balai Penyelidikan dan Pengembangan-Teknologi (BPPTK)], captured the spirit and content of a recent workshop about Merapi and Merapi-type volcanoes.

  18. Tephra hazard assessment at Concepcin Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Scaini, C.; Folch, A.; Navarro, M.

    2012-03-01

    Concepcin volcano in Ometepe Island, Nicaragua, is a highly active volcano with a rich historical record of explosive eruptions. Tephra fallout from Concepcin jeopardizes the surrounding populations, whereas volcanic ash clouds threat aerial navigation at a regional level. The assessment of these hazards is important for territorial planning and adoption of mitigation measures. Here we compute probabilistic hazard maps for Concepcin volcano considering three different eruptive scenarios based on past reference events. Previous geological analysis is used to quantify the eruption parameters of the reference events. We account for uncertainties in the definition of the scenarios trough probability density functions. A representative meteorological dataset is created for each scenario by running the WRF-ARW mesoscale meteorological model over a typical meteorological year, defined in terms of wind speed and direction at a given atmospheric height. Tephra transport and deposition under different eruption and wind conditions is modelled using the FALL3D dispersion model. For each scenario, simulations are combined to build probabilistic hazard maps for critical values of tephra load and for threshold values of airborne ash concentration at relevant flight levels. Results are useful to identify the expected impacts for each eruption type and aim at improving the assessment and management of risk in the region.

  19. Mineralized microbes from Giggenbach submarine volcano

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Jolly, G. E.; Scott, B.

    2009-12-01

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

  1. A new VLSI architecture for a single-chip-type Reed-Solomon decoder

    NASA Technical Reports Server (NTRS)

    Hsu, I. S.; Truong, T. K.

    1989-01-01

    A new very large scale integration (VLSI) architecture for implementing Reed-Solomon (RS) decoders that can correct both errors and erasures is described. This new architecture implements a Reed-Solomon decoder by using replication of a single VLSI chip. It is anticipated that this single chip type RS decoder approach will save substantial development and production costs. It is estimated that reduction in cost by a factor of four is possible with this new architecture. Furthermore, this Reed-Solomon decoder is programmable between 8 bit and 10 bit symbol sizes. Therefore, both an 8 bit Consultative Committee for Space Data Systems (CCSDS) RS decoder and a 10 bit decoder are obtained at the same time, and when concatenated with a (15,1/6) Viterbi decoder, provide an additional 2.1-dB coding gain.

  2. Hydrologic data collection activities in the Solomon Gulch basin near Valdez, Alaska

    USGS Publications Warehouse

    Bigelow, B.B.

    1988-01-01

    In 1981, the Alaska Power Authority completed construction of a dam spillway at the north end of Solomon Lake near Valdez. Regulation and diversion from the dam since 1982 have significantly altered the natural flow characteristics of Solomon Gulch. In September 1986, the Geological Survey began data collection to determine mean daily discharge at four sites below Solomon Lake and thus document the effects of regulation and diversion of water on the flow at various points in the system. Periodic discharge measurements and continuous records of water stage were obtained at two of the sites, and daily discharge values were computed for all four sites. The report contains descriptions of the data collection sites and the discharge records for each site for September 1986 and water year 1987. (USGS)

  3. A comparison of VLSI architectures for time and transform domain decoding of Reed-Solomon codes

    NASA Technical Reports Server (NTRS)

    Hsu, I. S.; Truong, T. K.; Deutsch, L. J.; Satorius, E. H.; Reed, I. S.

    1988-01-01

    It is well known that the Euclidean algorithm or its equivalent, continued fractions, can be used to find the error locator polynomial needed to decode a Reed-Solomon (RS) code. It is shown that this algorithm can be used for both time and transform domain decoding by replacing its initial conditions with the Forney syndromes and the erasure locator polynomial. By this means both the errata locator polynomial and the errate evaluator polynomial can be obtained with the Euclidean algorithm. With these ideas, both time and transform domain Reed-Solomon decoders for correcting errors and erasures are simplified and compared. As a consequence, the architectures of Reed-Solomon decoders for correcting both errors and erasures can be made more modular, regular, simple, and naturally suitable for VLSI implementation.

  4. Template-Free Synthesis of a Molecular Solomon Link by Two-Component Self-Assembly.

    PubMed

    Song, Young Ho; Singh, Nem; Jung, Jaehoon; Kim, Hyunuk; Kim, Eun-Hee; Cheong, Hae-Kap; Kim, Yousoo; Chi, Ki-Whan

    2016-02-01

    A molecular Solomon link was synthesized in high yield through the template-free, coordination-driven self-assembly of a carbazole-functionalized donor and a tetracene-based dinuclear ruthenium(II) acceptor. The doubly interlocked topology was realized by a strategically chosen ligand which was capable of participating in multiple CH???? and ?-? interactions, as evidenced from single-crystal X-ray analysis and computational studies. This method is the first example of a two-component self-assembly of a molecular Solomon link using a directional bonding approach. The donor alone was not responsible for the construction of the Solomon link, and was confirmed by its noncatenane self-assemblies obtained with other similar ruthenium(II) acceptors. PMID:26709952

  5. Stigmaphyllon patricianum-firmenichianum (Malpighiaceae), a new species from Loyalty Islands, New Caledonia

    PubMed Central

    Butaud, Jean-François

    2015-01-01

    Abstract A new species of Stigmaphyllon (Malpighiaceae) is described: Stigmaphyllon patricianum-firmenichianum Butaud. It is restricted to the coral islands of Ouvéa, Lifou and Maré in the Loyalty Islands Province (New Caledonia) and is most similar to Stigmaphyllon discolor (Gand.) C.E.Anderson, known from New Caledonia and Solomon Islands. Previously, plants now known as Stigmaphyllon patricianum-firmenichianum were included in Stigmaphyllon taomense (Baker f.) C.E.Anderson, endemic to the northern part of Grande-Terre and Belep Islands (New Caledonia). A new circumscription of Stigmaphyllon taomense is proposed. The regional key for New Caledonian species of Stigmaphyllon is updated. PMID:26312047

  6. Regional setting of a complex backarc: New Hebrides Arc, northern Vanatu-eastern Solomon Islands

    NASA Astrophysics Data System (ADS)

    Johnson, D. P.; Maillet, P. C.; Price, R.

    1993-06-01

    New GLORIA imagery over the complex backarc area of the northern New Hebrides Arc clearly outlines the deeply faulted Jean Charcot Troughs. The troughs are 2400 3000 m deep and are not magmatically active. They appear to be fragmented older crust and are not backarc basins in the usual sense. Horst and graben structures on the Hazel Holme Fracture Zone (HHFZ) cut obliquely across the trend of the Zone, which therefore is not a simple transform. The enechelon ridges may form a relay, but Y-shaped grabens could be remnant spreading zones, formed earlier in the history of the western part of the North Fiji Basin.

  7. 75 FR 18056 - Safety Zone; Fireworks Display, Patuxent River, Solomons Island Harbor, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-09

    ... Patuxent River. This action is necessary to provide for the safety of life on navigable waters during a... when the agency for good cause finds that those procedures are ``impracticable, unnecessary, or contrary to the public interest.'' Under 5 U.S.C. 553(b)(B), the Coast Guard finds that good cause...

  8. Greek Islands, Western Asia Minor as seen from STS-58

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This north-looking view shows the western margin of Turkey (right) and the Dodecanese Islands of Greece between the Aegean Sea (left) and the Sea of Crete (foreground). The largest island is Crete (foreground) with the semicircular island of Thira beyond. Thira is dominated by the volcanoe Santorini. Two airplane contrails appear between the Turkish mainland and the large island of Rhodes immediately offshore. The narrow straits of the Dardanelles, joining the Black Sea to the Mediterranean, can be detected top left.

  9. A Submarine Perspective on Hawaiian Volcanoes

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Postwar improvements in navigation, sonar-based mapping, and submarine photography enabled the development of bathymetric maps, which revealed submarine morphologic features that could be dredged or explored and sampled with a new generation of manned and unmanned submersibles. The maps revealed debris fields from giant landslides, the great extent of rift zones radiating from volcanic centers, and two previously unknown submarine volcanoes named Mahukona and Loihi, the youngest Hawaiian volcano. About 70 major landslides cover half the flanks of the Hawaiian Ridge out to Midway Island. Some of the landslides attain lengths of 200 km and have volumes exceeding 5,000 km3. More recent higher resolution bathymetry and sidescan data reveal that many submarine eruptions construct circular, flat-topped, monogenetic cones; that large fields of young strongly alkalic lava flows, such as the North Arch and South Arch lava fields, erupt on the seafloor within several hundred km of the islands; and that alkalic lavas erupt during the shield stage on Kilauea and Mauna Loa. The North Arch flow field covers about 24,000 km2, has an estimated volume between about 1000 and 1250 km3, has flows as long as 108 km, and erupted from over 100 vents. The source and melting mechanisms for their production is still debated. The maps also displayed stair-step terraces, mostly constructed of drowned coral reefs, which form during early rapid subsidence of the volcanoes during periods of oscillating sea level. The combination of scuba and underwater photography facilitated the first motion pictures of the mechanism of formation of pillow lava in shallow water offshore Kilauea. The age progression known from the main islands was extended westward along the Hawaiian Ridge past Midway Island, around a bend in the chain and northward along the Emperor Seamounts. Radiometric dating of dredged samples from these submarine volcanoes show that the magma source that built the chain has been active for over 80 Ma and established the remarkable linearity of the age-progression along the chain. Glass rinds on submarine lava quenched at depth contain initial magmatic volatiles and yield data on the juvenile water, sulfur, CO2, and rare gas contents of basaltic magmas, and continue to reveal nuances of the volatile contents of lava. Rock sampling at Loihi Seamount led to the discovery of the pre-shield alkalic phase of Hawaiian volcanism, which mirrors the well-known post-shield alkalic phase. Lava compositions from the Hawaiian Ridge and Emperor Seamounts have clear affinities to present-day Hawaiian lavas, but subtle source differences as well. The progression from small to large and back to small degrees of melting at individual volcanoes and the compositional changes along the chain constrain the melting processes and source compositions of Hawaiian volcanism. Coupling the age of lavas with that of submerged coral reefs has provided data on the growth and subsidence of volcanic centers. This information has meshed nicely with the age, composition, and morphology of lavas from the 3.2-km-deep Hawaiian Scientific Drill Hole. Submarine studies have taught us much about the workings of Hawaiian Volcanoes, and in the process have stimulated new work and concepts on marine volcanism worldwide.

  10. Diverse deformation patterns of Aleutian volcanoes from InSAR

    USGS Publications Warehouse

    Lu, Zhiming; Dzurisin, D.; Wicks, C., Jr.; Power, J.

    2008-01-01

    Interferometric synthetic aperture radar (InSAR) is capable of measuring ground-surface deformation with centimeter-to-subcentimeter precision at a spatial resolution of tens of meters over an area of hundreds to thousands of square kilometers. With its global coverage and all-weather imaging capability, InSAR has become an increasingly important measurement technique for constraining magma dynamics of volcanoes over remote regions such as the Aleutian