Science.gov

Sample records for volcano solomon islands

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  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. 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.

  4. 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.

  5. 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.

  6. Ancylostoma ceylanicum Hookworm in the Solomon Islands

    PubMed Central

    Hii, Sze Fui; Harrington, Humpress; Speare, Richard; Traub, Rebecca

    2017-01-01

    Although hookworm is highly prevalent in the Solomon Islands, the species involved are unknown. We initiated this study in response to finding Ancylostoma ceylanicum hookworm in a peacekeeper in Australia who had returned from the Solomon Islands. Kato-Katz fecal surveys performed in 2013 and 2014 in 2 village groups in East Malaita, Solomon Islands, identified hookworm-positive samples. These specimens were tested by cytochrome oxidase 1 (cox-1) gene multiplex PCR and sequenced. Of 66 positive specimens, 54 (81.8%) contained only Necator americanus, 11 (16.7%) contained only A. ceylanicum, and 1 (1.5%) contained both species. A. duodenale was not found. Haplotype analysis of cox-1 sequences placed all human isolates (99% bootstrap support) of A. ceylanicum within the zoonotic clade rather than the human-specific clade. This study confirms that A. ceylanicum is endemic in the East Malaita region of this Pacific Island nation. The strain of the A. ceylanicum in this region can be shared among humans, dogs, and cats. PMID:28098526

  7. Pre-Deployment Handbook: Solomon Islands

    DTIC Science & Technology

    2014-06-01

    poor standards of general hygiene, and inadequate sanitation, make malaria and tuberculosis endemic throughout the Solomon Islands. The most...from any of these symptoms. 116 Food & Water Risks. Gastro-intestinal infections are the most common illnesses. Proper food handling, drinking...hydrated. “Doxy” anti- malaria medications significantly increase the risk of sunburn. 119 Infection . Even small cuts and abrasions will require immediate

  8. 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…

  9. 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…

  10. 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

  11. 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.

  12. Solomon Islands: reaching street children in Honiara.

    PubMed

    Gatu, R

    2000-01-01

    The situation of homeless children in Honiara, Solomon Islands had attracted the attention of Sister Doreen of the Angelican Sisters of the Church. One discovery was that these young people had little knowledge of sexuality but were often sexually active. This article discusses the workshop developed by the Angelican Sisters of the Church that addresses the needs of the youth, particularly on the topics of adolescent sexual and reproductive health and HIV/AIDS and sexually transmitted diseases (STDs). About 34 young people attended the 4-day seminar, which aimed to empower the kids into making the right decision and changing their behavior. Among the activities during the program were the use of games, information and practical sessions, which included a condom demonstration in the form of a bingo game. The workshop was a success, with kids started teaching their peers and parents and more requests for such workshops indicated that young people in Honoria are hungry for information on sex, sexuality, HIV/AIDS and STDs.

  13. Telemedicine in the Solomon Islands: 2006 to 2009.

    PubMed

    Martiniuk, Alexandra; Negin, Joel; Hersch, Fred; Dalipanda, Tenneth; Jagilli, Rooney; Houasia, Patrick; Gorringe, Lilijana; Christie, Annie

    2011-01-01

    Telemedicine has been used in the Solomon Islands since 2000. We used quantitative and qualitative methods to examine telemedicine use in the Solomon Islands from January 2006 to June 2009. During the study period 66 telemedicine cases were submitted to the store and forward telemedicine system being used there. These included orthopaedic, oncology, cardiothoracic, infectious, congenital, gastroenterology and dermatology cases. Most cases (52%) were submitted by doctors at the National Referral Hospital (NRH) in Honiara. The majority of responses came from the NRH (27%). A final, firm recommendation regarding patient diagnosis and/or care was given for 46% of the cases. Interviews were conducted with 23 stakeholders in the Solomon Islands and in Australia to better understand the current and future use of telemedicine. The interviews identified the fragility of the Solomon Islands infrastructure, including the lack of training, as the largest barrier to the future use of telemedicine. The best use of telemedicine appears to be case sharing within the Solomon Islands, with connections to clinicians in other countries as a secondary benefit when particular expertise is required.

  14. 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.

  15. Solomon Islands Pijin: Grammar Handbook. Peace Corps Language Handbook Series.

    ERIC Educational Resources Information Center

    Huebner, Thom; Horoi, Stephen Rex

    This grammar handbook analyzes the rules of Solomon Islands Pijin and provides exercises on them. It is divided into 24 lessons. The first part of each lesson is a description of some element or function of the language, with examples; the second part is made up of oral and written exercises. The volume concludes with appendices on the personal…

  16. Haemophilus ducreyi associated with skin ulcers among children, Solomon Islands.

    PubMed

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

    2014-10-01

    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.

  17. 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…

  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.

  19. 75 FR 18056 - Safety Zone; Fireworks Display, Patuxent River, Solomons Island Harbor, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-09

    ... Island Harbor, MD AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a temporary safety zone upon specified waters of Solomons Island Harbor, a tributary of the... fireworks display launched from discharge barge located in Solomons Island, Calvert County, Maryland....

  20. Sector wide approaches for health in small island states: lessons learned from the Solomon Islands.

    PubMed

    Negin, Joel; Martiniuk, Alexandra

    2012-01-01

    Sector Wide Approaches (SWAps) have increasingly been implemented in countries around the world as a mechanism for effective delivery of health sector funding from various sources. Despite the global focus on aid effectiveness, SWAps have been under-examined. In 2007, the Solomon Islands and development partners began discussing a health SWAp making the Solomon Islands one of the first fragile states globally to adopt a SWAp. This paper explores the establishment and implementation of a health SWAp in the Solomon Islands as a specific case study with lessons learned for the region as well as for aid architecture in fragile states more generally. Tensions between donors and the government impeded agreement and early implementation and country ownership of the SWAp idea was muted. Since mid-2009, however, the Solomon Islands SWAp has made strong progress with greater government ownership and with more focus on partnership and harmonisation rather than on funding mechanisms. The SWAp mechanism has been a challenge for the capacity-constrained Solomon Islands health sector and for development partners familiar with other aid modalities, but current momentum suggests that the SWAp will have a positive impact on adherence to agreed aid effectiveness principles.

  1. 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.

  2. 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.

  3. 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…

  4. Emergency safe spaces in Haiti and the Solomon Islands.

    PubMed

    Madfis, Josh; Martyris, Daryl; Triplehorn, Carl

    2010-07-01

    This paper provides background information on emergency Safe Spaces for children and specific information for responses in Haiti and the Solomon Islands. In 2007, both countries experienced natural disasters that resulted in internal displacement of thousands of people. The Save the Children Alliance created Safe Spaces for children living in camps for internally displaced persons. The project sought to accomplish 'B-SAFE' strategies through emergency education, psychosocial, and protection interventions. The B-SAFE strategies are to (B)uild relationships, cooperation, and respect among peers; to (S)creen for high-risk children and youth; (A)ctive, structured learning and life saving information; to (F)acilitate children's natural resilience and a return to normalcy; and to (E)stablish a sense of security and self-esteem. The project made use of child and parent surveys and observation tools that measured B-SAFE indicators. Analysed data demonstrated an improvement in children's behavior participating in the programme.

  5. 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.

  6. A Case of Ancylostoma ceylanicum Infection Occurring in an Australian Soldier Returned from Solomon Islands

    PubMed Central

    Speare, Rick; Bradbury, Richard Stewart; Croese, John

    2016-01-01

    A 26-year-old male member of the Australian Defense Force presented with a history of central abdominal pain of 4 weeks duration and peripheral eosinophilia consistent with eosinophilic enteritis. Acute hookworm disease was diagnosed as the cause. Adult worms recovered from feces after therapy with albendazole were morphologically consistent with Ancylostoma ceylanicum. As the patient had been deployed with the Regional Assistance Mission to Solomon Islands for 6 months prior to this presentation, it is very likely that the A. ceylanicum was acquired in Solomon Islands. Until now, it has been assumed that any Ancylostoma spp. recovered from humans in Solomon Islands is A. duodenale. However, this case demonstrates that human hookworm infection acquired in the Solomon Islands could be caused by A. ceylanicum. PMID:27658607

  7. Social determinants of disability-based disadvantage in Solomon islands.

    PubMed

    Gartrell, Alexandra; Jennaway, Megan; Manderson, Lenore; Fangalasuu, Judy; Dolaiano, Simon

    2016-08-25

    Development discourse widely recognises that disability is the result of economic and social processes and structures that fail to accommodate persons with disabilities. Empirical work on the relationship between disability and poverty however, conceptualize poverty through an economic resource lens in high-income countries. To address this conceptual gap this article uses a social determinants of health perspective to examine how socio-cultural, economic and political contexts shape disability-based disadvantage. This article draws upon ethnographic research and supplementary data collected using rapid assessment techniques in Solomon Islands. Findings suggest that the disability-poverty nexus and inequalities in health, wellbeing and quality of life must be understood within broader patterns of social vulnerability that are institutionalised in landownership and patterns of descent, gendered power relations and disability specific stigmas that preclude social and productive engagement . This article demonstrates how a social determinant of health perspective that closely examines lived experiences of disability provides critical analytical insights into the structural mechanisms that constitute disability-based disadvantage. This article provides foundation knowledge on which policies and further research to promote disability-inclusion and equity can be based.

  8. 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…

  9. 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

  10. 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.

  11. Solomon Islands: Summary Report. Educational Experience Survey: Education, Language and Literacy Experience. Asia-South Pacific Education Watch

    ERIC Educational Resources Information Center

    de Guzman, Sylvia

    2007-01-01

    The Education Watch initiative is being implemented in the Solomon Islands by the Coalition on Education Solomon Islands (COESI) in partnership with Asian South Pacific Bureau of Adult Education (ASPBAE). COESI aims to generate a reliable body of information that will: (1) Accurately explain how much the national government has done and can do to…

  12. 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 μg g(-1). Total arsenic concentrations in the majority of marine and terrestrial samples collected were below 2 μg 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.

  13. Bridging near and remote Oceania: mtDNA and NRY variation in the Solomon Islands.

    PubMed

    Delfin, Frederick; Myles, Sean; Choi, Ying; Hughes, David; Illek, Robert; van Oven, Mannis; Pakendorf, Brigitte; Kayser, Manfred; Stoneking, Mark

    2012-02-01

    Although genetic studies have contributed greatly to our understanding of the colonization of Near and Remote Oceania, important gaps still exist. One such gap is the Solomon Islands, which extend between Bougainville and Vanuatu, thereby bridging Near and Remote Oceania, and include both Austronesian-speaking and Papuan-speaking groups. Here, we describe patterns of mitochondrial DNA (mtDNA) and nonrecombining Y chromosome (NRY) variation in over 700 individuals from 18 populations in the Solomons, including 11 Austronesian-speaking groups, 3 Papuan-speaking groups, and 4 Polynesian Outliers (descended via back migration from Polynesia). We find evidence for ancient (pre-Lapita) colonization of the Solomons in old NRY paragroups as well as from M2-M353, which probably arose in the Solomons ∼9,200 years ago and is the most frequent NRY haplogroup there. There are no consistent genetic differences between Austronesian-speaking and Papuan-speaking groups, suggesting extensive genetic contact between them. Santa Cruz, which is located in Remote Oceania, shows unusually low frequencies of mtDNA and NRY haplogroups of recent Asian ancestry. This is in apparent contradiction with expectations based on archaeological and linguistic evidence for an early (∼3,200 years ago), direct colonization of Santa Cruz by Lapita people from the Bismarck Archipelago, via a migration that "leapfrogged" over the rest of the Solomons. Polynesian Outliers show dramatic island-specific founder events involving various NRY haplogroups. We also find that NRY, but not mtDNA, genetic distance is correlated with the geographic distance between Solomons groups and that historically attested spheres of cultural interaction are associated with the recent genetic structure of Solomons groups, as revealed by mtDNA HV1 sequence and Y-STR haplotype diversity. Our results fill an important lacuna in human genetic studies of Oceania and aid in understanding the colonization and genetic history of

  14. Increased Rotavirus Prevalence in Diarrheal Outbreak Precipitated by Localized Flooding, Solomon Islands, 2014.

    PubMed

    Jones, Forrest K; Ko, Albert I; Becha, Chris; Joshua, Cynthia; Musto, Jennie; Thomas, Sarah; Ronsse, Axelle; Kirkwood, Carl D; Sio, Alison; Aumua, Audrey; Nilles, Eric J

    2016-05-01

    Flooding on 1 of the Solomon Islands precipitated a nationwide epidemic of diarrhea that spread to regions unaffected by flooding and caused >6,000 cases and 27 deaths. Rotavirus was identified in 38% of case-patients tested in the city with the most flooding. Outbreak potential related to weather reinforces the need for global rotavirus vaccination.

  15. Increased Rotavirus Prevalence in Diarrheal Outbreak Precipitated by Localized Flooding, Solomon Islands, 2014

    PubMed Central

    Jones, Forrest K.; Ko, Albert I.; Becha, Chris; Joshua, Cynthia; Musto, Jennie; Thomas, Sarah; Ronsse, Axelle; Kirkwood, Carl D.; Sio, Alison; Aumua, Audrey

    2016-01-01

    Flooding on 1 of the Solomon Islands precipitated a nationwide epidemic of diarrhea that spread to regions unaffected by flooding and caused >6,000 cases and 27 deaths. Rotavirus was identified in 38% of case-patients tested in the city with the most flooding. Outbreak potential related to weather reinforces the need for global rotavirus vaccination. PMID:27088272

  16. 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…

  17. 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.

  18. Solomon Islands Pijin: Culture and Communication Handbook. Peace Corps Language Handbook Series.

    ERIC Educational Resources Information Center

    Huebner, Thom; Horoi, Stephen Rex

    This handbook of the Pijin language is divided into four parts: (1) survival language skills, (2) situations in which the Peace Corps volunteer is likely to be involved, (3) getting the job done, and (4) information on the culture of the Solomon Islands. It establishes classroom activities that require the students to exchange messages in a way…

  19. "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.

  20. 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,…

  1. 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…

  2. Students' Beliefs about Learning Mathematics: Some Findings from the Solomon Islands

    ERIC Educational Resources Information Center

    Kele, Andriane; Sharma, Sashi

    2014-01-01

    Students' beliefs and attitudes can impact on their mathematics learning and performance. Yet, there appears to be minimal literature that deals with the educational implications of this dimension. This paper focuses on the beliefs of Year 12 Solomon Islands students in mathematics learning. The students' beliefs are analysed and themes…

  3. "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 <κ). The 144 'original research' publications included 115 (80%) 'descriptive studies' (κ = 0.82); 19 (13%) 'intervention studies' (κ = 0.77); and 10 (7%) 'measurement studies'(κ = 0.80). Key themes identified in the focus group discussion challenged historical inequities evident from the

  4. Sequence stratigraphy, structure, and tectonic history of the southwestern Ontong Java Plateau adjacent to the North Solomon Trench and Solomon Islands Arc

    NASA Astrophysics Data System (ADS)

    Phinney, Eric J.; Mann, Paul; Coffin, Millard F.; Shipley, Thomas H.

    1999-09-01

    The Ontong Java Plateau (OJP) is the largest and thickest oceanic plateau on Earth and one of the few oceanic plateaus actively converging on an island arc. We present velocity determinations and geologic interpretation of 2000 km of two-dimensional, multi-channel seismic data from the southwestern Ontong Java Plateau, North Solomon Trench, and northern Solomon Islands. We recognize three megasequences, ranging in age from early Cretaceous to Quaternary, on the basis of distinct interval velocities and seismic stratigraphic facies. Megasequence OJ1 is early Cretaceous, upper igneous crust of the OJP and correlates with basalt outcrops dated at 122-125 Ma on the island of Malaita. The top of the overlying megasequence OJ2, a late Cretaceous mudstone unit, had been identified by previous workers as the top of igneous basement. Seismic facies and correlation to distant Deep Sea Drilling Project/Ocean Drilling Program sites indicate that OJ2 was deposited in a moderately low-energy, marine environment near a fluctuating carbonate compensation depth that resulted in multiple periods of dissolution. OJ2 thins south of the Stewart Arch onto the Solomon Islands where it is correlated with the Kwaraae Mudstone Formation. Megasequence OJ3 is late Cretaceous through Quaternary pelagic cover which caps the Ontong Java Plateau; it thickens into the North Solomon Trench, and seismic facies suggest that OJ3 was deposited in a low-energy marine environment. We use seismic facies analysis, sediment thickness, structural observations, and quantitative plate reconstructions of the position of the OJP and Solomon Islands to propose a tectonic, magmatic, and sedimentary history of the southwestern Ontong Java Plateau. Prior to 125 Ma late Jurassic and early Cretaceous oceanic crust formed. From 125 to 122 Ma, the first mantle plume formed igneous crust (OJ1). Between 122 and 92 Ma, marine mudstone (OJ2 and Kwaraae mudstone of Malaita, Solomon Islands) was deposited on Ontong Java

  5. 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.

  6. Historical Analysis of Population Reactions to Stimuli - A Case Study of the Solomon Islands

    DTIC Science & Technology

    2007-03-01

    as events) in regional populations. The first three studies focussed on East Timor, Aceh, and Papua New Guinea and Papua, and helped to develop the...Aceh and Papua New Guinea . This is an item of note as the histories are very different as are the time frames for the study. This might be an...ethnic groups are key aspects of a societal memory that operates within the Solomon Islands. This is different to Papua New Guinea , where no or

  7. Intraslab rupture triggering megathrust rupture coseismically in the 17 December 2016 Solomon Islands Mw 7.9 earthquake

    NASA Astrophysics Data System (ADS)

    Lay, Thorne; Ye, Lingling; Ammon, Charles J.; Kanamori, Hiroo

    2017-02-01

    The 17 December 2016 Solomon Islands earthquake (Mw 7.9) initiated 103 km deep in the subducting Solomon Sea slab near the junction of the Solomon Islands and New Britain trenches. Most aftershocks are located near the Solomon Islands plate boundary megathrust west of Bougainville, where previous large interplate thrust faulting earthquakes occurred in 1995 (Mw 7.7) and 1971 (Mw 8.0). Teleseismic body wave modeling and aftershock relocations indicate that the initial 30 s of the 2016 rupture occurred over depths of 90 to 120 km on an intraslab fault dipping 30° to the southwest, almost perpendicular to the dipping slab interface. The next 50 s of rupture took place at depths of 32 to 47 km in the deeper (Domain C) portion of the overlying megathrust fault dipping 35° to the northeast. High susceptibility to triggering in the region accounts for this compound rupture of two separate fault planes.

  8. Interactions between sea-level rise and wave exposure on reef island dynamics in the Solomon Islands

    NASA Astrophysics Data System (ADS)

    Albert, Simon; Leon, Javier X.; Grinham, Alistair R.; Church, John A.; Gibbes, Badin R.; Woodroffe, Colin D.

    2016-05-01

    Low-lying reef islands in the Solomon Islands provide a valuable window into the future impacts of global sea-level rise. Sea-level rise has been predicted to cause widespread erosion and inundation of low-lying atolls in the central Pacific. However, the limited research on reef islands in the western Pacific indicates the majority of shoreline changes and inundation to date result from extreme events, seawalls and inappropriate development rather than sea-level rise alone. Here, we present the first analysis of coastal dynamics from a sea-level rise hotspot in the Solomon Islands. Using time series aerial and satellite imagery from 1947 to 2014 of 33 islands, along with historical insight from local knowledge, we have identified five vegetated reef islands that have vanished over this time period and a further six islands experiencing severe shoreline recession. Shoreline recession at two sites has destroyed villages that have existed since at least 1935, leading to community relocations. Rates of shoreline recession are substantially higher in areas exposed to high wave energy, indicating a synergistic interaction between sea-level rise and waves. Understanding these local factors that increase the susceptibility of islands to coastal erosion is critical to guide adaptation responses for these remote Pacific communities.

  9. Battle Experience; Solomon Islands Actions Information. Bulletin Number 4

    DTIC Science & Technology

    1942-11-01

    passing by the north of San Cristobal Island, arrived at Guadalcanal on the morning of November llth, 1942. The route north of San Cristobal was... Cristobal Island on the morning of the llth. The PORTLAND and JUNEAU were detached from Task Group 67.1 and joined Task Group 67.4. This group thereafter...to the north of San Cristobal Island. When news was received that Task Group 62.4 had been sighted by enemy seaplanes on the 10th, together with

  10. 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

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

    PubMed

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

    2013-01-01

    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.

  12. 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

  13. 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

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

    PubMed

    Spickett, Jeffery T; Katscherian, Dianne

    2014-06-25

    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.

  15. Vector-control response in a post-flood disaster setting, Honiara, Solomon Islands, 2014

    PubMed Central

    Musto, Jennie; Bugoro, Hugo; Butafa, Charles; Sio, Alison; Joshua, Cynthia

    2016-01-01

    Problem The close quartering and exposed living conditions in evacuation centres and the potential increase in vector density after flooding in Solomon Islands resulted in an increased risk of exposure for the occupants to vectorborne diseases. Context In April 2014, Solomon Islands experienced a flash flooding event that affected many areas and displaced a large number of people. In the capital, Honiara, nearly 10 000 people were housed in emergency evacuation centres at the peak of the post-flood emergency. At the time of the floods, the number of dengue cases was increasing, following a record outbreak in 2013. Action The National Vector Borne Disease Control Programme with the assistance of the World Health Organization implemented an emergency vector-control response plan to provide protection to the at-risk populations in the evacuation centres. The National Surveillance Unit also activated an early warning disease surveillance system to monitor communicable diseases, including dengue and malaria. Outcome Timely and strategic application of the emergency interventions probably prevented an increase in dengue and malaria cases in the affected areas. Discussion Rapid and appropriate precautionary vector-control measures applied in a post-natural disaster setting can prevent and mitigate vectorborne disease incidences. Collecting vector surveillance data allows better analysis of vector-control operations’ effectiveness. PMID:27757255

  16. Spatial Distribution and Sedimentary Facies of the 2007 Solomon Islands Tsunami Deposits

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.; Nishimura, Y.; Woodward, S.

    2007-12-01

    We conducted a field survey of the extent of damage, crustal deformation, and onshore deposits caused by 2007 Solomon Islands tsunami in Ghizo and adjacent islands in the western Solomon Islands, from 13th to 18th April, 2007. Our survey team was comprised of six Japanese and one American researcher. Three of us, the authors, mainly investigated tsunami deposits in three villages (Titiana, Suva, and Pailongge) in southern Ghizo Island. One member of our team re-investigated the deposits in June 2007. The tsunami generated sheet-like deposits of coral beach sand on the flat plain in Titiana. Beside the sea coast, the tsunami wave eroded ground surfaces and formed small scarps at 30 m from the sea. Just interior of the scarps, tsunami deposits accumulated up to 9 cm in thickness. The thickness decreased with distance from the sea and was also affected by microtopography. No sandy tsunami deposits were observed on the inland area between 170 m and 210 m from the sea. The upper boundary of inundation was recognized at about 210 m from the sea because of accumulation of driftwood and floating debris. In Suva and Pailongge, the outline of sand-sheet distribution is the same as it in Titiana. The tsunami had a maximum thickness of 10 cm and two or three sand layers are separated by thin humic sand layers. These humic layers were likely supplied from hillslopes eroded by the tsunami and transported by return-flows. These successions of deposits suggest that tsunami waves inundated at least two times. This is consistent with the number of large waves told by eyewitnesses. In the Solomon Islands, the plentiful rainfall causes erosion and resedimentation of tsunami deposits. Furthermore, the sedimentary structures will be destroyed by chemical weathering in warm and moist environment, and bioturbation by plants, animals, and human activities. The sedimentary structures had been preserved till the end of June 2007, but had already been penetrated by plant roots and sandpipes

  17. Defining Population Health Vulnerability Following an Extreme Weather Event in an Urban Pacific Island Environment: Honiara, Solomon Islands.

    PubMed

    Natuzzi, Eileen S; Joshua, Cynthia; Shortus, Matthew; Reubin, Reginald; Dalipanda, Tenneth; Ferran, Karen; Aumua, Audrey; Brodine, Stephanie

    2016-08-03

    Extreme weather events are common and increasing in intensity in the southwestern Pacific region. Health impacts from cyclones and tropical storms cause acute injuries and infectious disease outbreaks. Defining population vulnerability to extreme weather events by examining a recent flood in Honiara, Solomon Islands, can help stakeholders and policymakers adapt development to reduce future threats. The acute and subacute health impacts following the April 2014 floods were defined using data obtained from hospitals and clinics, the Ministry of Health and in-country World Health Organization office in Honiara. Geographical information system (GIS) was used to assess morbidity and mortality, and vulnerability of the health system infrastructure and households in Honiara. The April flash floods were responsible for 21 acute deaths, 33 injuries, and a diarrhea outbreak that affected 8,584 people with 10 pediatric deaths. A GIS vulnerability assessment of the location of the health system infrastructure and households relative to rivers and the coastline identified 75% of the health infrastructure and over 29% of Honiara's population as vulnerable to future hydrological events. Honiara, Solomon Islands, is a rapidly growing, highly vulnerable urban Pacific Island environment. Evaluation of the mortality and morbidity from the April 2014 floods as well as the infectious disease outbreaks that followed allows public health specialists and policy makers to understand the health system and populations vulnerability to future shocks. Understanding the negative impacts natural disaster have on people living in urban Pacific environments will help the government as well as development partners in crafting resilient adaptation development.

  18. Exploring the potential impacts of tourism development on social and ecological change in the Solomon Islands.

    PubMed

    Diedrich, Amy; Aswani, Shankar

    2016-11-01

    Pacific Island communities may be vulnerable to negative impacts of economic development, which is often considered a strategy for reducing vulnerability to environmental change. Studies that evaluate potential impacts of economic development in isolated communities may be inaccurate to only focus on asking people to anticipate impacts of phenomena they have had minimal exposure to. We used an open-ended approach to evaluate how communities in the Solomon Islands perceived change, and used this information to anticipate potential impacts of the government's plans to develop tourism. Our results showed mostly negative expectations of change, particularly socio-cultural, which was perceived as being driven by diminishing social capital, foreign influence, and economic development. Despite minimal exposure, locals supported tourism and had more positive expectations of change associated with this activity. Our findings emphasize the need for locally appropriate planning to ensure intended positive impacts of tourism and other forms of economic development.

  19. The Prevalence of Scabies and Impetigo in the Solomon Islands: A Population-Based Survey

    PubMed Central

    Marks, Michael; Sokana, Oliver; Solomon, Anthony W.; Mabey, David C.; Romani, Lucia; Kaldor, John; Steer, Andrew C.; Engelman, Daniel

    2016-01-01

    Background Scabies and impetigo are common, important and treatable skin conditions. Reports from several Pacific island countries show extremely high prevalence of these two conditions, but for many countries, including the Solomon Islands, there is a paucity of epidemiological data. Methodology Ten rural villages in the Western Province of the Solomon Islands were included in the study, chosen so that data collection could be integrated with an existing project investigating clinical and serological markers of yaws. All residents were eligible to participate, and 1908 people were enrolled. Participants were interviewed and examined by a paediatric registrar, who recorded relevant demographic information, and made a clinical diagnosis of scabies and/or impetigo, severity and distribution. Principal Findings The total unweighted prevalence of scabies was 19.2% (95% confidence interval [CI] 17.5–21.0), and age and gender weighted prevalence 19.2% (95%CI 16.7–21.9). The adult prevalence of scabies was 10.4% (95%CI 8.2–13.2), and the highest prevalence was found in infants < 1 year of age (34.1%, adjusted odds ratio [AOR] compared with adults: 3.6, 95%CI 2.2–6.0) and children aged 1–4 years (25.7%, AOR 2.6, 95%CI 1.7–3.9). Scabies affected two or more body regions in 80.9% of participants, and 4.4% of scabies cases were classified as severe. The total unweighted prevalence of active impetigo was 32.7% (95%CI 30.6–34.8), and age and gender weighted prevalence 26.7% (95%CI 24.2–29.5). The highest prevalence was found in children aged 1–4 years (42.6%, AOR compared with adults: 4.1, 95%CI 2.9–5.8). Scabies infestation was associated with active impetigo infection (AOR 2.0, 95%CI 1.6–2.6); with 41.1% of active impetigo cases also having scabies. Conclusions and Significance Scabies and impetigo are very common in the rural Western Province of the Solomon Islands. Scabies infestation is strongly associated with impetigo. Community control strategies

  20. Crustal deformation in the Western Solomon Islands revealed by GPS observation during 2009 - 2012

    NASA Astrophysics Data System (ADS)

    Kuo, Y.; Lin, K.; Ku, C.; Taylor, F. W.; Chen, Y.; Huang, B.

    2012-12-01

    The plate boundary along the southern margin of the Solomon Islands, southwestern Pacific, is characterized by convergent tectonic processes between the Indo-Australian Plate and Pacific Plate. The horizontal convergence rate between two plates is 135 mm/yr in the direction of N45°E. In terms of the structure, this subduction zone is relatively complicated because large seamounts are involved in subduction of extremely young lithosphere generated by the Woodlark spreading system. Hence, the crustal deformation is essential to reconstructing the structural model that constitutes and operates the entire subduction system. For the purpose of monitoring crustal motion, we began to deploy continuous mode GPS stations in September 2009. All of them have been working for 1-3 yr. The total horizontal rates are 95±1, 52±3, 78±7, 120±14, 114±7, and 114±7 mm/yr for Sibo, Nusu, Lale, Husu, Tepa, and Sege respectively. However, the moving directions are N23°E, N63°W, N10°W, N65°W, N63°W, and N69°W. During 2009, the uplift rates are -31±8 and 50±17 mm/yr for Sibo and Nusu, but during 2010, the rate are 2±2 and 13±9 mm/yr. The larger slips may cause of the postseismic deformation of 2007 Mw8.1 Solomon Earthquake. It also shows the large uplift rates on Husu (98±36 mm/yr), Tepa (60±11 mm/yr) and Sege (33±10 mm/yr) after the 2010 Mw7.1 Solomon Earthquake; however, it still needs longer measuring time to confirm the tectonic behavior.

  1. An Examination of Seismicity Linking the Solomon Islands and Vanuatu Subduction Zones

    NASA Astrophysics Data System (ADS)

    Neely, J. S.; Furlong, K. P.

    2015-12-01

    The Solomon Islands-Vanuatu composite subduction zone represents a tectonically complex region along the Pacific-Australia plate boundary in the southwest Pacific Ocean. Here the Australia plate subducts under the Pacific plate in two segments: the South Solomon Trench and the Vanuatu Trench. The two subducting sections are offset by a 200 km long, transform fault - the San Cristobal Trough (SCT) - which acts as a Subduction-Transform Edge Propagator (STEP) fault. The subducting segments have experienced much more frequent and larger seismic events than the STEP fault. The northern Vanuatu trench hosted a M8.0 earthquake in 2013. In 2014, at the juncture of the western terminus of the SCT and the southern South Solomon Trench, two earthquakes (M7.4 and M7.6) occurred with disparate mechanisms (dominantly thrust and strike-slip respectively), which we interpret to indicate the tearing of the Australia plate as its northern section subducts and southern section translates along the SCT. During the 2013-2014 timeframe, little seismic activity occurred along the STEP fault. However, in May 2015, three M6.8-6.9 strike-slip events occurred in rapid succession as the STEP fault ruptured east to west. These recent events share similarities with a 1993 strike-slip STEP sequence on the SCT. Analysis of the 1993 and 2015 STEP earthquake sequences provides constraints on the plate boundary geometry of this major transform fault. Preliminary research suggests that plate motion along the STEP fault is partitioned between larger east-west oriented strike-slip events and smaller north-south thrust earthquakes. Additionally, the differences in seismic activity between the subducting slabs and the STEP fault can provide insights into how stress is transferred along the plate boundary and the mechanisms by which that stress is released.

  2. Sulfated steroids: ptilosteroids A-C and ptilosaponosides A and B from the Solomon Islands marine sponge Ptilocaulis spiculifer.

    PubMed

    Gabant, Marion; Schmitz-Afonso, Isabelle; Gallard, Jean-François; Menou, Jean-Louis; Laurent, Dominique; Debitus, Cécile; Al-Mourabit, Ali

    2009-04-01

    Three new pregnanes, ptilosteroid A (1), ptilosteroid B (2), and ptilosteroid C (3), and two new pregnane glycosides, ptilosaponoside A (4) and ptilosaponoside B (5), were isolated from the marine sponge Ptilocaulis spiculifer collected in the Solomon Islands. The structures were determined by spectroscopic methods. Biological tests of these compounds showed that they are not cytotoxic against KB cells.

  3. 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.

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

    USGS Publications Warehouse

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

    1997-01-01

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

  5. Polymorphisms associated with a tropical climate and root crop diet induce susceptibility to metabolic and cardiovascular diseases in Solomon Islands

    PubMed Central

    Naka, Izumi; Yamauchi, Taro; Natsuhara, Kazumi; Eddie, Ricky; Kimura, Ryosuke; Nakazawa, Minato; Ishida, Takafumi; Ohtsuka, Ryutaro; Ohashi, Jun

    2017-01-01

    The people of the Solomon Islands represent an Austronesian (AN)-speaking population’s adaptation to a humid tropical environment and subsistence of tuberous crops. Genome-wide association studies (GWASs) of other populations (e.g. the Human Genome Diversity Project [HGDP]) have suggested the existence of genotypes adaptive to ecoregion, diet, and subsistence, and that those genotypes are also associated with metabolic and cardiovascular diseases. Recently, the incidence of non-communicable diseases has been increasing in the Solomon Islands. In the present study, we explored the association of genotypes adaptive to a tropical environment and tuberous crop diet with metabolic and cardiovascular conditions in rural and urban AN-speaking Melanesian and Micronesian populations of the Solomon Islands. A total of 561 participants were genotyped for single nucleotide polymorphisms (SNPs) potentially associated with a tropical environment (rs174570 and rs2237892) and a tuberous crop diet (rs162036, rs185819, and rs2722425). The results showed that the allele frequencies of the Solomon Islands populations adopted patterns similar to those in populations from other hot, tropical areas with a tuberous crop diet in previous studies. Furthermore, rs162036, rs185819, rs2237892, and rs2722425 were all strongly associated with one or more metabolic and cardiovascular conditions. The derived allele of rs2722425 (i.e. rs2722425-G) was significantly associated with an elevated LDL level (P = 0.000264) even after the significance level was adjusted for multiple testing (i.e., α = 0.0005). Our results suggest that the inhabitants of the Solomon Islands exhibit the effects of the tropical environment and tuberous crop diet on their allele frequencies, and that their susceptibility to metabolic and cardiovascular diseases is therefore considered to be associated with their environment and diet. PMID:28253292

  6. Polymorphisms associated with a tropical climate and root crop diet induce susceptibility to metabolic and cardiovascular diseases in Solomon Islands.

    PubMed

    Furusawa, Takuro; Naka, Izumi; Yamauchi, Taro; Natsuhara, Kazumi; Eddie, Ricky; Kimura, Ryosuke; Nakazawa, Minato; Ishida, Takafumi; Ohtsuka, Ryutaro; Ohashi, Jun

    2017-01-01

    The people of the Solomon Islands represent an Austronesian (AN)-speaking population's adaptation to a humid tropical environment and subsistence of tuberous crops. Genome-wide association studies (GWASs) of other populations (e.g. the Human Genome Diversity Project [HGDP]) have suggested the existence of genotypes adaptive to ecoregion, diet, and subsistence, and that those genotypes are also associated with metabolic and cardiovascular diseases. Recently, the incidence of non-communicable diseases has been increasing in the Solomon Islands. In the present study, we explored the association of genotypes adaptive to a tropical environment and tuberous crop diet with metabolic and cardiovascular conditions in rural and urban AN-speaking Melanesian and Micronesian populations of the Solomon Islands. A total of 561 participants were genotyped for single nucleotide polymorphisms (SNPs) potentially associated with a tropical environment (rs174570 and rs2237892) and a tuberous crop diet (rs162036, rs185819, and rs2722425). The results showed that the allele frequencies of the Solomon Islands populations adopted patterns similar to those in populations from other hot, tropical areas with a tuberous crop diet in previous studies. Furthermore, rs162036, rs185819, rs2237892, and rs2722425 were all strongly associated with one or more metabolic and cardiovascular conditions. The derived allele of rs2722425 (i.e. rs2722425-G) was significantly associated with an elevated LDL level (P = 0.000264) even after the significance level was adjusted for multiple testing (i.e., α = 0.0005). Our results suggest that the inhabitants of the Solomon Islands exhibit the effects of the tropical environment and tuberous crop diet on their allele frequencies, and that their susceptibility to metabolic and cardiovascular diseases is therefore considered to be associated with their environment and diet.

  7. 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.

  8. 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

  9. 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

  10. Melt Inclusion Evidence for Subduction-modified Mantle Beneath the Woodlark Spreading Center, Solomon Islands

    NASA Astrophysics Data System (ADS)

    Chadwick, J.; Turner, A.; Collins, E.

    2015-12-01

    The Woodlark Spreading Center (WSC) to the east of Papua New Guinea separates the Indo-Australian plate and Solomon Sea microplate. At its eastern terminus, the WSC is being subducted at the New Britain trench, forming a triple junction near the New Georgia Group arc in the Solomon Islands. Previous studies have shown that lavas recovered from greater than 100 km from the trench on the WSC are N-MORB, but closer to the trench they have arc-like Sr-Nd-Pb isotopic ratios, enrichments in LILE, and depletions in HFSE. In the complex triple junction area of the WSC on the Simbo and Ghizo Ridges, island arc tholeiites to medium-K calc-alkaline andesites and dacites have been recovered, many with trace element and isotopic characteristics that are similar to the true arc lavas in the New Georgia Group on the other side of the trench. We suggest that subduction-modified arc mantle migrates through slab windows created by the subduction of the WSC as the plates continue to diverge after subduction. This transfer of mantle across the plate boundary leads to variable mixing between arc and N-MORB end-members, forming the hybrid to arc-like lavas recovered on the WSC. To test this hypothesis and to characterize the end-member compositions, we have analyzed melt inclusions in olivine, pyroxene, and plagioclase phenocrysts in Simbo and Ghizo Ridge lava samples. Major elements were analyzed using the electron microprobe facility at Fayetteville State University and volatiles were analyzed on the ion probe facility at Woods Hole Oceanographic Institution. The melt inclusions show a wide diversity of magmas from basalts to dacites, and mixing modeling shows that most Woodlark Spreading Center lava compositions are explained by mixing between the most extreme mafic (MORB) and felsic (arc) inclusion compositions.

  11. 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.

  12. 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

  13. Origin Of Pyroxenites From San Jorge And Santa Isabel (Solomon Islands).

    NASA Astrophysics Data System (ADS)

    Berly, T.

    2001-12-01

    The Solomon Islands are a NW to SE-trending double chain of islands, the older basement of which was formed by SW-directed subduction of the Pacific Plate beneath the Indo-Australian Plate, between the Eocene and Early Miocene. At 10 Ma, the Ontong Java Plateau (OJP) collided with the Solomon arc, and in response to this collision, a polarity reversal of subduction occurred; NE-directed subduction beneath the Solomon arc began. Consequent to this collision, thin fault slices of peridotites, pyroxenites, gabbros, and basalts, some of which are demonstrably obducted OJP, are now exposed in SE Santa Isabel and neighbouring San Jorge. The pyroxenites are associated with harzburgites, dunites and sometimes incorporated into serpentine massifs (NW San Jorge). These fresh, coarse-grained rocks contain variable proportions of orthopyroxene (70

  14. Hospital visits due to domestic violence from 1994 to 2011 in the Solomon Islands: a descriptive case series.

    PubMed

    Farrell, Penny C; Negin, Joel; Houasia, Patrick; Munamua, Alex B; Leon, David P; Rimon, Mia; Martiniuk, Alexandra L C

    2014-09-01

    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.

  15. 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

  16. Petroleum prospects for offshore sedimentary basins in the eastern Papua New Guinea and Solomon Islands regions

    SciTech Connect

    Bruns, T.R.; Vedder, J.G. )

    1990-06-01

    Intra-arc basins in the Buka-Bougainville region of Papua New Guinea and in the Solomon Islands contain thick sedimentary sequences that may be prospective for petroleum. The Queen Emma basin, between Bougainville and New Ireland, contains as much as 8 km of deformed Oligocene and younger strata. The Central Solomons Trough, which underlies New Georgia Sound, is a composite intra-arc basin that contains late Oligocene and younger strata as much as 7 km thick. Farther east, beneath Indispensable Strait, the down-faulted Indispensable basin locally contains as much as 5.4 km of Miocene( ) and younger strata, and the offshore part of Mbokokimbo basin off eastern Guadalcanal includes 6 km or more of late Miocene and younger strata. All of these basins have some of the attributes necessary to generate and trap petroleum. Structural and stratigraphic traps are common, including faulted anticlines, sedimentary wedges, and carbonate reefs and reef-derived deposits on submarine ridges and along the basin margins. The thickness of the basin deposits ensures that some strata are buried deeply enough to be within the thermal regime required for hydrocarbon generation. However, little source or reservoir rock information is available because of the lack of detailed surface and subsurface stratigraphy. Moreover, much of the basin sediment is likely to consist of volcaniclastic material, derived from uplifted volcanogenic rocks surrounding the basins, and may be poor in source and reservoir rocks. Until additional stratigraphic information is available, analysis of the petroleum potential of these basins is a matter of conjecture.

  17. 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

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

    PubMed

    Albert, Simon; Aswani, Shankar; Fisher, Paul L; Albert, Joelle

    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.

  19. 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

  20. A new species of Abyssocladia (Porifera, Demospongiae, Poecilosclerida, Cladorhizidae) and other carnivorous sponges from the far eastern Solomon Islands.

    PubMed

    Vacelet, Jean; Kelly, Michelle

    2014-06-16

    Two species, one each of Abyssocladia Lévi, 1964, and Asbestopluma Topsent, 1901, are recorded from the far eastern Solomon Islands for the first time. Abyssocladia lakwollii sp. nov. is characterized by the pedunculate disc-shape of the body, the unusually large size of the isochelae I microscleres, and by the shape of the cleistochelae with crossed central teeth. Asbestopluma (A.) desmophora Kelly & Vacelet, 2011, first described from a seamount on Macquarie Ridge (Australia EEZ) and eastern waters to the north and south of New Zealand, is also recorded from the far eastern Solomon Islands. The specimens differ only slightly from their southern counterparts in dimensions of some spicules, and in the ornamentation detail of the basal teeth of the large and small anisochelae. 

  1. 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…

  2. Crustal deformation in the Western Solomon Islands revealed by GPS observation and D_InSAR during 2009 - 2013

    NASA Astrophysics Data System (ADS)

    Kuo, Y. T.; Ku, C. S.; Wang, Y.; Lin, Y. N. N. N.; Chen, Y. G.; Lin, K. C.; Huang, B. S.; Hsu, Y. J.; Taylor, F. W.

    2014-12-01

    The Solomon Islands are located in the southwestern Pacific, where the Australian Plate underthrusts the Solomon Plate towards ~N70 E at a rate of ~100 mm/yr. The Coleman seamount on the Australian plate is impinging on the forearc at Rendova Island and may cause both the seismicity and tectonic behavior to be more complicated than usual. Hence, an understanding o f the ongoing crustal deformation is essential to reconstructing the structural framework that controls the entire subduction system, particularly earthquake generation on the megathrust fault and possible subsidiary faults. Based on the results from GPS and D_InSAR, the horizontal velocity profiles across the trench for areas of the forearc to the west and to the east of the impinging Coleman seamount show different characteristics. The eastern profile shows convergence rates of ~100 mm/yr only 10 km from the trench at the western end of the Tetepare Island, and the western profile reaches 70 mm/yr at 30 km from the trench. This difference might be caused by the shallow locked depth consistent with co-seismic slip located extremely close to the trench during the Mw 7.1 Solomon Earthquake on 3rd January, 2010. We have a hypothesis to argue that the behavior of the fault geometry should be very different on the two sides of the seamount. However, the coupling ratio could be realized by further detailed analysis.

  3. Influence of development factors on nutritional patterns in the Solomon Islands.

    PubMed

    Joseph, F G

    1981-01-01

    Looks at the general changes brought about by development, and how the nutritional habits of the Solomon Island communities have been affected by development. The development aspirations of Third World countries include the introduction of cash crops for foreign exchange; moving away from subsistence-type economy and self-reliance in feeding one's family to dependence on outside sources; employment of more people at salaried jobs, small industries and factories; and modernization. Many governments view these developmental approaches as a positive way of progressive development, despite the unfavorable changes that they bring. These changes need to be examined and studied by socio-political authorities. Before development, communities throughout the South Pacific islands lived on various root crops, other starches, such as bread fruit and bananas, and a variety of green leaves. Animal fats, oils, butter, and sauces were not used. The cooking process was superior to western methods because the nutrient content of food was preserved. Little meat or milk was eaten because of the absence of edible animals. Protein sources consisted of seafood and occasionally wild or domestic pig. Birds were eaten on some islands. Though no gross malnutrition was observed, studies have shown that dietary intake was borderline and there wre varying degrees of vitamin deficiencies. There was minimal high blood pressure, obesity, cardiovascular diseases, or bowel pathology. Development, however, brought new dietary patterns and cases of malnutrition have been seen. Though the situation is not serious, it is of concern because it is affecting school children. National policies which take into account human factors are needed to begin to solve such dietary problems. Communities should be encouraged to continue producing and consuming tuberous crops and unrefined plant starches. Laws should be created to moderate drinking and advertisements for foreign foods should be restricted. Unless

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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…

  9. Investigating Rainfall Variability in the South Pacific Convergence Zone using the Geochemistry of Stalagmites from the Solomon Islands

    NASA Astrophysics Data System (ADS)

    Sekhon, N.; Quinn, T. M.; Partin, J. W.; Edwards, R. L.; Cheng, H.

    2015-12-01

    The South Pacific Convergence Zone (SPCZ), which extends southeastward from New Guinea to Tahiti, is the largest perennial rainfall feature in the Southern Hemisphere. The position of the SPCZ and its associated rainfall varies significantly on multidecadal timescales, as documented by instrumental and climate proxy data. For example, stalagmite δ18O records (rainfall proxy) from Espiritu Santo, Vanuatu (Partin et al., 2013) and Guadalcanal, Solomon Islands (Maupin et al., 2014), document large (~1‰), abrupt changes in stalagmite δ18O on multidecadal timescales over the past 600 years that arise from internal variability in the climate system. The proxy data agree with the type of rainfall changes observed in the instrumental record, such as the change across 1976/77, but the older changes are larger in relative magnitude. We expand on these earlier studies of rainfall variability in the SPCZ system using stable isotope variations in stalagmites from two other locations in the Solomon Islands (Munda, New Georgia, 8.3°S, 157.3°E; Suku, Nggela Pile (9.8° S, 160.2° E). These stalagmites range in age from about 400 CE to 1850 CE, based on U-Th dating, and have relatively fast growth rates (60 to 300 µm/yr). Stalagmite δ18O time series were generated from sub-samples milled every 500 µm, or approximately 1 to 8 years per data point. Initial results from these two new Solomon Island stalagmites not only confirm the presence of multidecadal variability in stalagmite δ18O identified in previous studies, but suggest that the same amplitude of variability has occurred over several windows of time during the past 1600 years. When complete, these new proxy rainfall records from Munda and Suku will further constrain the pattern and mechanism of SPCZ rainfall variability in western tropical Pacific region.

  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. Y-chromosome diversity is inversely associated with language affiliation in paired Austronesian- and Papuan-speaking communities from Solomon Islands.

    PubMed

    Cox, Murray P; Mirazón Lahr, Marta

    2006-01-01

    The Solomon Islands lie in the center of Island Melanesia, bordered to the north by the Bismarck Archipelago and to the south by Vanuatu. The nation's half-million inhabitants speak around 70 languages from two unrelated language groups: Austronesian, a language family widespread in the Pacific and closely related to languages spoken in Island Southeast Asia, and "East Papuan", generally defined as non-Austronesian and distantly related to the extremely diverse Papuan languages of New Guinea. Despite the archipelago's presumed role as a staging post for the settlement of Remote Oceania, genetic research on Solomon Island populations is sparse. We collected paired samples from two regions that have populations speaking Austronesian and Papuan languages, respectively. Here we present Y-chromosome data from these samples, the first from Solomon Islands. We detected five Y-chromosome lineages: M-M106, O-M175, K-M9*, K-M230, and the extremely rare clade, K1-M177. Y-chromosome lineages from Solomon Islands fall within the range of other Island Melanesian populations but display markedly lower haplogroup diversity. From a broad Indo-Pacific perspective, Y-chromosome lineages show partial association with the distribution of language groups: O-M175 is associated spatially with Austronesian-speaking areas, whereas M-M106 broadly correlates with the distribution of Papuan languages. However, no relationship between Y-chromosome lineages and language affiliation was observed on a small scale within Solomon Islands. This pattern may result from a sampling strategy that targeted small communities, where individual Y-chromosome lineages can be fixed or swept to extinction by genetic drift or favored paternal exogamy.

  12. 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 δ18O time series, within dating uncertainties, favors the interpretation that the stalagmite δ18O 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 δ18O 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

  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. Highly divergent molecular variants of human T-lymphotropic virus type I from isolated populations in Papua New Guinea and the Solomon Islands.

    PubMed Central

    Gessian, A; Yanagihara, R; Franchini, G; Garruto, R M; Jenkins, C L; Ajdukiewicz, A B; Gallo, R C; Gajdusek, D C

    1991-01-01

    To determine the molecular genetic relationship between Melanesian strains of human T-lymphotropic virus type I (HTLV-I) and cosmopolitan prototype HTLV-I, we amplified by PCR, then cloned, and sequenced a 522-base-pair region of the HTLV-I env gene in DNA extracted from uncultured (fresh) and cultured peripheral blood mononuclear cells obtained from six seropositive Melanesian Papua New Guineans and Solomon Islanders, including a Solomon Islander with HTLV-I myeloneuropathy. Unlike isolates of HTLV-I from Japan, the West Indies, the Americas, and Africa, which share greater than or equal to 97% sequence homology, the Melanesian strains of HTLV-I were only 91.8%-92.5% identical with a prototype Japanese HTLV-IATK-1. The nucleotide sequence of proviral DNA from the Solomon Islander with HTLV-I myeloneuropathy also diverged markedly from that of HTLV-I isolated from Japanese patients with HTLV-I-associated myelopathy and from Jamaican patients with tropical spastic paraparesis, suggesting that these variant viruses are capable of causing disease. The HTLV-I variants from Papua New Guineans, in turn, differed by nearly 4% from the Melanesian variants from Solomon Islanders, indicating the existence of another HTLV-I quasi-species. By contrast, HTLV-I strains from two residents of Bellona Island, a Polynesian Outlier within the Solomon Islands, were closely related to cosmopolitan prototype HTLV-I (greater than or equal to 97% sequence identity), suggesting recent introduction, possibly during this century. These findings are consistent with a proto-Melanesian HTLV-I strain of archaic presence, which evolved independently of contemporary cosmopolitan strains, and pose new questions about the origin and global dissemination of HTLV-I. Images PMID:1881912

  15. 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.

  16. Observing the Historic Eruption of Northern Mariana Islands Volcano

    NASA Astrophysics Data System (ADS)

    Wiens, Douglas A.; Shore, Patrick J.; Sauter, Allan; Hilton, David R.; Fischer, Tobias; Camacho, Juan T.

    2004-01-01

    Anatahan volcano erupted for the first time in recorded history at about 7:30 GMT on 10 May 2003, covering the island of Anatahan, in the Commonwealth of the Northern Mariana Islands (CNMI), with ash, and providing scientists with important opportunities to study this volcano. The eruption was first reported by the National Oceanic and Atmospheric Administration's Volcanic Ash Advisory Center at 12:32 GMT, based on satellite images of the ash cloud. At about the same time, unusual light flares were observed from an approaching small ship, the Super Emerald, which was carrying a group of seismologists from Washington University in St. Louis, Scripps Institution of Oceanography, and the CNMI Emergency Management Office. As morning broke, the ship was approximately 10 km from the island, and those on board witnessed billowing ash and gas rise from the volcano's caldera to form a great cloud exceeding 6 km in altitude (Figure 1). The scientists were in the region installing land seismographs for the Mariana Subduction Factory Imaging Experiment, a joint U.S.-Japanese deployment of 20 land broadband seismographs and 58 ocean bottom seismographs funded (on the U.S. side) by the Margins program of the National Science Foundation. The experiment has the goal of imaging the magma production regions and mantle flow patterns within the upper mantle beneath the Mariana arc and backarc (see http://epsc.wustl.edu/seismology/MARIANA).

  17. 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…

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  20. 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.

  1. The Effect of the Great Barrier Reef on the Propagation of the 2007 Solomon Islands Tsunami Recorded in Northeastern Australia

    NASA Astrophysics Data System (ADS)

    Baba, Toshitaka; Mleczko, Richard; Burbidge, David; Cummins, Phil R.; Thio, Hong Kie

    2008-12-01

    The effect of offshore coral reefs on the impact from a tsunami remains controversial. For example, field surveys after the 2004 Indian Ocean tsunami indicate that the energy of the tsunami was reduced by natural coral reef barriers in Sri Lanka, but there was no indication that coral reefs off Banda Aceh, Indonesia had any effect on the tsunami. In this paper, we investigate whether the Great Barrier Reef (GBR) offshore Queensland, Australia, may have weakened the tsunami impact from the 2007 Solomon Islands earthquake. The fault slip distribution of the 2007 Solomon Islands earthquake was firstly obtained by teleseismic inversion. The tsunami was then propagated to shallow water just offshore the coast by solving the linear shallow water equations using a staggered grid finite-difference method. We used a relatively high resolution (approximately 250 m) bathymetric grid for the region just off the coast containing the reef. The tsunami waveforms recorded at tide gauge stations along the Australian coast were then compared to the results from the tsunami simulation when using both the realistic 250 m resolution bathymetry and with two grids having fictitious bathymetry: One in which the the GBR has been replaced by a smooth interpolation from depths outside the GBR to the coast (the “No GBR” grid), and one in which the GBR has been replaced by a flat plane at a depth equal to the mean water depth of the GBR (the “Average GBR” grid). From the comparison between the synthetic waveforms both with and without the Great Barrier Reef, we found that the Great Barrier Reef significantly weakened the tsunami impact. According to our model, the coral reefs delayed the tsunami arrival time by 5-10 minutes, decreased the amplitude of the first tsunami pulse to half or less, and lengthened the period of the tsunami.

  2. Seroprevalence of hepatitis B surface antigen in pregnant women attending antenatal clinic in Honiara Solomon Islands, 2015

    PubMed Central

    Getahun, Aneley; Baekalia, Margaret; Panda, Nixon; Lee, Alice; Puiahi, Elliot; Khan, Sabiha; Tahani, Donald; Manongi, Doris

    2016-01-01

    AIM To determine the seroprevalence of hepatitis B surface antigen (HBsAg) among pregnant women attending antenatal clinic in Honiara, Solomon Islands. METHODS This descriptive cross-sectional study was carried out in seven area health centers in Honiara. From March to June 2015, identification of eligible pregnant women in each site was conducted using systematic random sampling technique. A total of 243 pregnant women who gave written informed consent were enrolled. Standardized tool was used to record demographics, obstetric history and serology results. HBsAg and hepatitis B e antigen (HBeAg) were tested using point-of-care rapid diagnostic test. All HBsAg positive samples were verified using enzyme-linked immunosorbent assay. RESULTS The mean age of participants was 26 ± 6 years. The overall hepatitis HBsAg prevalence was 13.8% with higher rate (22%) reported in women between 30-34 years of age. Majority of HBsAg positive participants were Melanesians (29 out for 33). None of the pregnant women in the 15-19 years and ≥ 40 years tested positive for HBsAg. There was no statistically significant difference in HBsAg prevalence by age, ethnicity, education and residential location. The overall HBeAg seroprevalence was 36.7%. Women between 20-24 years of age had the highest rate of 54.5%. Low level of knowledge about hepatitis B vaccination was reputed. Overall, 54.6% of participants were not aware of their hepatitis B vaccination status and only 65.2% of mothers reported their child had been vaccinated. CONCLUSION Hepatitis B is a disease of public health importance in Solomon Islands and emphasize the need for integrated preventative interventions for its control. PMID:28008343

  3. Volcano growth and evolution of the island of Hawaii

    USGS Publications Warehouse

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

    1992-01-01

    The seven volcanoes comprising the island of Hawaii and its submarine base are, in order of growth, Mahukona, Kohala, Mauna Kea, Hualalai, Mauna Loa, Kilauea, and Loihi. The first four have completed their shield-building stage, and the timing of this event can be determined from the depth of the slope break associated with the end of shield building, calibrated using the ages and depths of a series of dated submerged coral reefs off northwest Hawaii. On each volcano, the transition from eruption of tholeiitic to alkalic lava occurs near the end of shield building. The rate of southeastern progression of the end of shield building in the interval from Haleakala to Hualalai is about 13 cm/yr. Based on this rate and an average spacing of volcanoes on each loci line of 40-60km, the volcanoes required about 600 thousand years to grow from the ocean floor to the time of the end of shield building. They arrive at the ocean surface about midway through this period. -from Authors

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

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

  6. Interseismic, coseismic, postseismic, and slow slip event deformation above a shallow subduction thrust in the western Solomon Islands

    NASA Astrophysics Data System (ADS)

    Wallace, L. M.; Taylor, F. W.; Bevis, M. G.; Phillips, D. A.; Walter, J. I.; Kendrick, E. C.; Papabatu, A. K.

    2015-12-01

    The western Solomon Islands are a remarkable natural laboratory to investigate processes occurring on the shallowest (<10 km depth) portions of the subduction interface. Islands within the New Georgia Group are located <15 km from the San Cristobal Trench, with the subduction thrust located only a few km beneath the southwest coast of islands like Rannonga and Rendova. This offers a globally unique opportunity to use GPS and other land-based methods to monitor deformation processes very close to the trench at a subduction zone. We present results from a campaign GPS network in the western Solomons that has been operated from 1996-present. The data from 1996-2002 indicate interseismic coupling on the shallow portion of the interface, at a rate of nearly 100% of the relative plate motion. Coupling does not appear to extend deeper than ~20 km depth, and the relatively shallow down-dip limit of coupling is consistent with subduction of young (<6 Ma) oceanic crust of the Woodlark Basin. We also show evidence for a slow slip event in late 2000, observed at a GPS site near Gizo that was running continuously from 1999-2002. In April 2007, an Mw 8.1 earthquake occurred on the subduction thrust beneath the network, resulting in large coseismic displacements at nearby campaign GPS sites. The earthquake caused widespread coastal uplift and subsidence in the region, as revealed by studies of coral microatolls following the earthquake (Taylor et al., 2008). We invert displacements of the GPS sites jointly with vertical displacements of coral microatolls to evaluate the coseismic slip during the earthquake. The area of the interface that underwent slip in the earthquake matches well with the region that was interseismically coupled just prior to the 2007 earthquake. The data also require large coseismic slip on the shallow interface near the trench, which likely contributed to the generation of a large, damaging tsunami following the earthquake. We also show results from a recent

  7. Volcano hazards and potential risks on St. Paul Island, Pribilof Islands, Bering Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Feeley, T. C.; Winer, G. S.

    2009-05-01

    Volcano hazards and potential risks on St. Paul Island, Alaska, are assessed on the basis of the recent volcanic history of the island. The long-term frequency of volcanic eruptions is estimated using a count of 40 identifiable vents considered to represent separate eruptions. Assuming regular temporal spacing of these events during the period 360,000 to 3230 y.b.p., the estimated mean recurrence time is 0.11 × 10 - 3 eruption/year and the eruptive interval is approximately 8900 years. Volcano hazards on St. Paul are associated exclusively with the eruption of low viscosity alkali basaltic magma. The most important are lava flows, tephra fallout, and base surges. Other hazards include volcanic gases, seismicity and ground deformation associated with dike intrusion beneath rift zones, and explosive lava-water interactions along coastal regions and water-saturated ground. The general characteristics of past volcanism on St. Paul indicate that the most likely styles of future eruptions will be (1) Hawaiian-style eruptions with fire fountains and pahoehoe lava flows issuing from one of two polygenetic shield volcanoes on the island; (2) Strombolian-style, scoria cone-building eruptions with associated tephra fallout and eruption of short pahoehoe lava flows; and (3) explosive Surtseyan-style, phreatomagmatic eruptions initiating at some point along St. Paul's insular shelf. Given the relatively restricted range in volcanic phenomena on St. Paul, the most significant question regarding volcano hazard and risk assessment is whether future eruptions will be confined to the same region on the island as the most recent activity. If future activity follows the recent past, resulting volcano hazards will most likely be located at inland areas sufficiently far from habitation that they will pose little threat to life or property. An important caveat, however, is that St. Paul is constructed almost entirely from the products of volcanic eruptions with vents located all over

  8. 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

  9. 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

  10. 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

  11. Impact of ethnic conflict on the nutritional status and quality of life of suburban villagers in the Solomon Islands.

    PubMed

    Yamauchi, Taro; Nakazawa, Minato; Ohmae, Hiroshi; Kamei, Kiseko; Sato, Kanae; Bakote'e, Bernard

    2010-01-01

    This paper describes the health and nutritional status and quality of life (QOL) of suburban villagers in the Solomon Islands 3 y after the 1998-2003 ethnic conflict. Cross-sectional data were obtained from a small community located 50 km east of the capital city (n=206, 87 adults and 119 children). A health survey involving urine analysis, anthropometry, and blood pressure measurements was conducted to assess health and nutritional status and child growth. Simultaneously, 57 non-randomly selected adults participated in the QOL questionnaire survey. Results of anthropometry show that participants had good health and nutritional status (mean BMIs: 22.8 and 21.7 for men and women, respectively) and 73% of boys and 83% of girls were judged `normal body size' based on their BMI values. Urinalysis revealed that 88% of the participants were healthy and indicated that they consumed considerable amounts of purchased food such as rice and tinned meat. These findings suggest that the population's lifestyle had essentially recovered from the ethnic conflict. However, possible consequences of the ethnic conflict on the QOL scores were observed in the environmental domain. This study found a positive association between body fat and QOL. This could be interpreted in terms of the traditionally positive view of large bodies in the South Pacific and as resulting from unstable social conditions prevailing after the ethnic conflict.

  12. Knowledge, Attitudes, and Practices regarding Diarrhea and Cholera following an Oral Cholera Vaccination Campaign in the Solomon Islands

    PubMed Central

    Burnett, Eleanor; Dalipanda, Tenneth; Ogaoga, Divi; Gaiofa, Jenny; Jilini, Gregory; Halpin, Alison; Dietz, Vance; Date, Kashmira; Mintz, Eric; Hyde, Terri; Wannemuehler, Kathleen; Yen, Catherine

    2016-01-01

    Background In response to a 2011 cholera outbreak in Papua New Guinea, the Government of the Solomon Islands initiated a cholera prevention program which included cholera disease prevention and treatment messaging, community meetings, and a pre-emptive cholera vaccination campaign targeting 11,000 children aged 1–15 years in selected communities in Choiseul and Western Provinces. Methodology and Principal Findings We conducted a post-vaccination campaign, household-level survey about knowledge, attitudes, and practices regarding diarrhea and cholera in areas targeted and not targeted for cholera vaccination. Respondents in vaccinated areas were more likely to have received cholera education in the previous 6 months (33% v. 9%; p = 0.04), to know signs and symptoms (64% vs. 22%; p = 0.02) and treatment (96% vs. 50%; p = 0.02) of cholera, and to be aware of cholera vaccine (48% vs. 14%; p = 0.02). There were no differences in water, sanitation, and hygiene practices. Conclusions This pre-emptive OCV campaign in a cholera-naïve community provided a unique opportunity to assess household-level knowledge, attitudes, and practices regarding diarrhea, cholera, and water, sanitation, and hygiene (WASH). Our findings suggest that education provided during the vaccination campaign may have reinforced earlier mass messaging about cholera and diarrheal disease in vaccinated communities. PMID:27548678

  13. 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.

  14. Use of a duodenal serosal patch in the repair of a colon rupture in a female Solomon Island eclectus parrot.

    PubMed

    Briscoe, Jeleen A; Bennett, R Avery

    2011-04-01

    Case Description-A 444-g (0.98-lb) 4-year-old sexually intact female Solomon Island eclectus parrot (Eclectus roratus solomonensis) was referred and evaluated for a suspected colonic obstruction. Clinical Findings-The parrot had a 3-day history of not passing feces and lack of appetite following treatment of dystocia that included percutaneous collapse of the egg and manual removal of egg fragments via the cloaca. During this procedure, a tear in the cloacal mucosa developed. The tear was repaired via a midline cloacotomy. Although clinically stable at the time of referral, the parrot became lethargic and bradycardic and had delayed crop emptying. Treatment and Outcome-A midline celiotomy and cloacotomy were performed to relieve the colonic obstruction, during which the severely distended colon ruptured. The colonic defects were closed in a simple interrupted pattern, and a serosal patch was applied by use of the adjacent duodenum. The bird recovered uneventfully from anesthesia and was passing voluminous feces with mildly increased effort within 1 hour after surgery. At 3 weeks after surgery, the parrot was passing feces with no increase in effort and had a normal appetite. Clinical Relevance-Application of a duodenal serosal patch for repair of a colon rupture was successful in this parrot. Gastrointestinal obstruction is rare in birds, but should be considered in birds that have regurgitation, decreased fecal production, and gastrointestinal dilation. Because birds lack an omentum, serosal patching with adjacent duodenum should be considered as a viable option in avian surgery.

  15. Energy released at Teide Volcano,Tenerife, Canary Islands

    NASA Astrophysics Data System (ADS)

    Lopez, D. L.; Perez, N. M.; Marrero, R.

    2003-12-01

    Teide volcano (3715 m high) is located at the northern scarp of the Las Ca¤adas caldera, a large depression at the center of Tenerife Island. Las Ca¤adas has been produced by multiple episodes of caldera collapse and giant landslides. The basanite-phonolite magmatic system associated with Teide volcano is emitting gases that reach the summit producing weak fumaroles. The chemical composition of these fumaroles and the flux of diffuse soil CO2 degassing at the summit cone (0.5 km2) has been used to determine the energy released as passive degassing in this volcano. Previous investigations show that Teide's summit is emitting 400 tons m2 day-1 of CO2 to the atmosphere. The composition of CH4, CO2, CO, and H2O indicate a chemical equilibrium temperature of 234° C and 75% condensation of water vapor within the volcanic edifice (Chiodini and Marini, 1998). The composition of the gases before condensation was restored and assumed to represent the composition at the equilibrium zone. The energy stored by the gases at the equilibration zone is assumed to be released as the gases move towards the discharge zone. The following processes are considered: change in pressure and temperature for water from the equilibration zone to the zone of condensation, latent heat released during the water condensation process, cooling of the condensed water from the condensation temperature to ambient temperature, and change of pressure and temperature for CO2 from the equilibrium to the discharge zone. Thermodynamic calculations of the energy released in each one of these processes indicate that 144 MW are released at Teide. Energy flux is 288 MW m-2. Most of this energy is released during the condensation process. This energy output compares with other hydrothermal systems of the world. These results show that during periods of passive degassing, fumarolic activity is limited by the geometry and elevation of the volcanic structure and the internal thermodynamic conditions.

  16. Volcano-Hydrothermal Systems of the Central and Northern Kuril Island Arc - a Review

    NASA Astrophysics Data System (ADS)

    Kalacheva, E.; Taran, Y.; Voloshina, E.; Ptashinsky, L.

    2015-12-01

    More than 20 active volcanoes with historical eruptions are known on 17 islands composing the Central and Northern part of the Kurilian Arc. Six islands - Paramushir, Shiashkotan, Rasshua, Ushishir, Ketoy and Simushir - are characterized by hydrothermal activity, complementary to the fumarolic activity in their craters. There are several types of volcano-hydrothermal systems on the islands. At Paramushir, Shiashkotan and Ketoy the thermal manifestations are acidic to ultra-acidic water discharges associated with hydrothermal aquifers inside volcano edifices and formed as the result of the absorption of magmatic gases by ground waters. A closest known analogue of such activity is Satsuma-Iwojima volcano-island at the Ryukyu Arc. Another type of hydrothermal activity are wide spread coastal hot springs (Shiashkotan, Rasshua), situated as a rule within tide zones and formed by mixing of the heated seawater with cold groundwater or, in opposite, by mixing of the steam- or conductively heated groundwater with seawater. This type of thermal manifestation is similar to that reported for other volcanic islands of the world (Satsuma Iwojima, Monserrat, Ischia, Socorro). Ushishir volcano-hydrothermal system is formed by the absorption of magmatic gases by seawater. Only Ketoy Island hosts a permanent acidic crater lake. At Ebeko volcano (Paramushir) rapidly disappearing small acidic lakes (formed after phreatic eruptions) have been reported. The main hydrothermal manifestation of Simushir is the Zavaritsky caldera lake with numerous coastal thermal springs and weak steam vents. The last time measured temperatures of fumaroles at the islands are: >500ºC at Pallas Peak (Ketoy), 480ºC at Kuntamintar volcano (Shiashkotan), variable and fast changing temperatures from 120º C to 500ºC at Ebeko volcano (Paramushir), 150ºC in the Rasshua crater, and > 300ºC in the Chirpoy crater (Black Brothers islands). The magmatic and rock-forming solute output by the Kurilian volcano

  17. 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.

  18. 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…

  19. 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

  20. Brucella abortus surveillance of cattle in Fiji, Papua New Guinea, Vanuatu, the Solomon Islands and a case for active disease surveillance as a training tool.

    PubMed

    Tukana, Andrew; Hedlefs, Robert; Gummow, Bruce

    2016-10-01

    There have been no surveys of the cattle population for brucellosis in the Pacific Island Countries and Territories (PICTs) for more than 15 years. This study used disease surveillance as a capacity building training tool and to examine some of the constraints that impede surveillance in PICTs. The study also developed and implemented a series of surveys for detecting antibodies to B. abortus in cattle in Fiji, Papua New Guinea, Vanuatu and the Solomon Islands contributing to OIE requirements. The findings indicated lack of funds, lack of technical capacity, shortage of veterinarians, high turnover of in-country officials and lack of awareness on the impacts of animal diseases on public health that were constraining active disease surveillance. During the development and implementation of the surveys, constraints highlighted were outdated census data on farm numbers and cattle population, lack of funds for mobilisation of officials to carry out the surveys, lack of equipment for collecting and processing samples, lack of staff knowledge on blood sampling, geographical difficulties and security in accessing farms. Some of the reasons why these were constraints are discussed with likely solutions presented. The detection surveys had the objectives of building capacity for the country officials and demonstrating freedom from brucellosis in cattle for PNG, Vanuatu and the Solomon Islands. PNG, Vanuatu and the Solomon Islands all demonstrated freedom from bovine brucellosis in the areas surveyed using the indirect ELISA test. Fiji had an outbreak of brucellosis, and the objective was to determine its distribution and prevalence on untested farms. The Muaniweni district surveyed during the training had a 95 % confidence interval for true prevalence between 1.66 and 5.45 %. The study showed that active disease surveillance could be used as a tool for training officials thus, improves surveillance capacity in resource poor countries.

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. Modeling volcano growth on the Island of Hawaii: deep-water perspectives

    USGS Publications Warehouse

    Lipman, Peter W.; Calvert, Andrew T.

    2013-01-01

    Recent ocean-bottom geophysical surveys, dredging, and dives, which complement surface data and scientific drilling at the Island of Hawaii, document that evolutionary stages during volcano growth are more diverse than previously described. Based on combining available composition, isotopic age, and geologically constrained volume data for each of the component volcanoes, this overview provides the first integrated models for overall growth of any Hawaiian island. In contrast to prior morphologic models for volcano evolution (preshield, shield, postshield), growth increasingly can be tracked by age and volume (magma supply), defining waxing alkalic, sustained tholeiitic, and waning alkalic stages. Data and estimates for individual volcanoes are used to model changing magma supply during successive compositional stages, to place limits on volcano life spans, and to interpret composite assembly of the island. Volcano volumes vary by an order of magnitude; peak magma supply also varies sizably among edifices but is challenging to quantify because of uncertainty about volcano life spans. Three alternative models are compared: (1) near-constant volcano propagation, (2) near-equal volcano durations, (3) high peak-tholeiite magma supply. These models define inconsistencies with prior geodynamic models, indicate that composite growth at Hawaii peaked ca. 800–400 ka, and demonstrate a lower current rate. Recent age determinations for Kilauea and Kohala define a volcano propagation rate of 8.6 cm/yr that yields plausible inception ages for other volcanoes of the Kea trend. In contrast, a similar propagation rate for the less-constrained Loa trend would require inception of Loihi Seamount in the future and ages that become implausibly large for the older volcanoes. An alternative rate of 10.6 cm/yr for Loa-trend volcanoes is reasonably consistent with ages and volcano spacing, but younger Loa volcanoes are offset from the Kea trend in age-distance plots. Variable magma flux

  7. 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.

  8. Temporal magma source changes at Gaua volcano, Vanuatu island arc

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    Gaua Island (also called Santa Maria), from the central part of the Vanuatu arc, consists of a large volcano marked by a caldera that hosts the active Mount Garet summit cone. In this paper, a geochemical study including Sr, Nd, Pb and Hf isotopic compositions of 25 lavas emitted since 1.8 Ma is presented, with a focus on the volcanic products that preceded (old volcanics, main cone and pyroclastic series) and followed (Mount Garet) the caldera forming event. All lavas show an island arc signature with enrichment in LILE and depletion in HFSE. Post-caldera lavas define a medium-K calc-alkaline trend, whereas lavas from the former main cone have high-K calc-alkaline compositions. Compared to the pre-caldera volcanic suite, the Mount Garet lavas have similar Th/Nb ( 1.5), 143Nd/144Nd ( 0.51295) and 176Hf/177Hf ( 0.28316) ratios, but higher Ba/La ( 42 vs. 27) and 87Sr/86Sr (0.70417 vs. 0.70405) ratios and lower Ce/Pb ( 2.7 vs. 4.6), La/Sm ( 2.5 vs. 4.0) and 206Pb/204Pb (18.105 vs. 18.176) ratios. High Th/Nb and low Nd and Hf isotopic ratios compared to N-MORB suggest the contribution of 2% of subducted sediment melt to the mantle source of Gaua magmas. Most of the observed differences between pre- and post-caldera lavas can be accounted for by the involvement of at least two portions of the mantle wedge, metasomatized by different slab-derived aqueous fluids. In addition, the lower La/Sm (at a given 143Nd/144Nd) ratios of Mount Garet lavas suggest a higher degree of partial melting ( 10-15%) compared to the pre-caldera lavas ( 5%). The Santa Maria Pyroclastic Series (SMPS) eruption probably triggered the caldera collapse, in response to emptying of the magmatic chamber. This event may have allowed new access to the surface for a geochemically distinct batch of magma issued from a separate magma chamber, resulting in the birth and construction of Mount Garet within the caldera. As both magmatic suites were emitted over a very short time, the storage of their parental

  9. The First Historical Eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Fischer, T. P.; Hilton, D. R.; Demoor, J.; Jaffe, L.; Spilde, M. N.; Counce, D.; Camacho, J. T.

    2003-12-01

    The first historical eruption of Anatahan volcano occurred on May 10, 2003. The MARGINS office responded by authorizing helicopter surveillance and ship deployment to visit the volcano. The helicopter flight on May 19 allowed visual observations and identification of the east crater as the source of the eruption. The top of the plume was estimated to be at 10,000 ft - significantly less than the 30,000 ft of the initial blast. No bombs were ejected out of the east crater at this time but were falling back into the crater. The bombs looked irregular in shape, massive and were estimated to be a few m in diameter. Bombs and tephra samples were collected from the eastern side of the island when blasts were occurring at a rate of approx. 1 per 5min. The ship visit followed on May 21 to the western side of the island for collection of samples and SO2 flux measurements, along with maintenance of a previously deployed seismometer. Volcanic samples collected on Anatahan consisted of bombs, ash and scoria from the present eruption and old lavas (age unknown). The ash section on the western shore was 25 cm thick and consisted of the following sequence (bottom to top): 0-5 inversely? graded dark ash with scoria and pumice clasts (1-2 cm), 20-25 cm: well sorted clast-supported scoria (max 2 cm) with some fine ash. The maximum total thickness measured at a site 6 km from the east crater was approximately 45 cm. The sequence is interpreted as 1) initial blast 2) interaction of magma with water (from pre-existing hydrothermal system) as evidenced by accretionary lapilli 3) magmatic phase of the eruption producing juvenile material. Electron microprobe analyses of the pumice and scoria show uniform compositions of ~ 60wt% SiO2 in the glass; zoned plagioclase with average composition of 61% An, 37.7% Ab, 1.2% Or; pyroxenes (19.4% Wo, 53.4% En, 26.7% Fs) and Fe-Ti oxides. Sulfur and Cl contents are approx. 100 and 1500 ppm, respectively. Water content of the glass may be several wt

  10. The May 2003 eruption of Anatahan volcano, Mariana Islands: Geochemical evolution of a silicic island-arc volcano

    USGS Publications Warehouse

    Wade, J.A.; Plank, T.; Stern, R.J.; Tollstrup, D.L.; Gill, J.B.; O'Leary, J. C.; Eiler, J.M.; Moore, R.B.; Woodhead, J.D.; Trusdell, F.; Fischer, T.P.; Hilton, David R.

    2005-01-01

    The first historical eruption of Anatahan volcano began on May 10, 2003. Samples of tephra from early in the eruption were analyzed for major and trace elements, and Sr, Nd, Pb, Hf, and O isotopic compositions. The compositions of these tephras are compared with those of prehistoric samples of basalt and andesite, also newly reported here. The May 2003 eruptives are medium-K andesites with 59-63 wt.% SiO2, and are otherwise homogeneous (varying less than 3% 2?? about the mean for 45 elements). Small, but systematic, chemical differences exist between dark (scoria) and light (pumice) fragments, which indicate fewer mafic and oxide phenocrysts in, and less degassing for, the pumice than scoria. The May 2003 magmas are nearly identical to other prehistoric eruptives from Anatahan. Nonetheless, Anatahan has erupted a wide range of compositions in the past, from basalt to dacite (49-66 wt.% SiO2). The large proportion of lavas with silicic compositions at Anatahan (> 59 wt.% SiO2) is unique within the active Mariana Islands, which otherwise erupt a narrow range of basalts and basaltic andesites. The silicic compositions raise the question of whether they formed via crystal fractionation or crustal assimilation. The lack of 87Sr/86Sr variation with silica content, the MORB-like ??18O, and the incompatible behavior of Zr rule out assimilation of old crust, altered crust, or zircon-saturated crustal melts, respectively. Instead, the constancy of isotopic and trace element ratios, and the systematic variations in REE patterns are consistent with evolution by crystal fractionation of similar parental magmas. Thus, Anatahan is a type example of an island-arc volcano that erupts comagmatic basalts to dacites, with no evidence for crustal assimilation. The parental magmas to Anatahan lie at the low 143Nd/144Nd, Ba/La, and Sm/La end of the spectrum of magmas erupted in the Marianas arc, consistent with 1-3 wt.% addition of subducted sediment to the mantle source, or roughly one

  11. The May 2003 eruption of Anatahan volcano, Mariana Islands: Geochemical evolution of a silicic island-arc volcano

    NASA Astrophysics Data System (ADS)

    Wade, Jennifer A.; Plank, Terry; Stern, Robert J.; Tollstrup, Darren L.; Gill, James B.; O'Leary, Julie C.; Eiler, John M.; Moore, Richard B.; Woodhead, Jon D.; Trusdell, Frank; Fischer, Tobias P.; Hilton, David R.

    2005-08-01

    The first historical eruption of Anatahan volcano began on May 10, 2003. Samples of tephra from early in the eruption were analyzed for major and trace elements, and Sr, Nd, Pb, Hf, and O isotopic compositions. The compositions of these tephras are compared with those of prehistoric samples of basalt and andesite, also newly reported here. The May 2003 eruptives are medium-K andesites with 59-63 wt.% SiO 2, and are otherwise homogeneous (varying less than 3% 2 σ about the mean for 45 elements). Small, but systematic, chemical differences exist between dark (scoria) and light (pumice) fragments, which indicate fewer mafic and oxide phenocrysts in, and less degassing for, the pumice than scoria. The May 2003 magmas are nearly identical to other prehistoric eruptives from Anatahan. Nonetheless, Anatahan has erupted a wide range of compositions in the past, from basalt to dacite (49-66 wt.% SiO 2). The large proportion of lavas with silicic compositions at Anatahan (> 59 wt.% SiO 2) is unique within the active Mariana Islands, which otherwise erupt a narrow range of basalts and basaltic andesites. The silicic compositions raise the question of whether they formed via crystal fractionation or crustal assimilation. The lack of 87Sr/ 86Sr variation with silica content, the MORB-like δ18O, and the incompatible behavior of Zr rule out assimilation of old crust, altered crust, or zircon-saturated crustal melts, respectively. Instead, the constancy of isotopic and trace element ratios, and the systematic variations in REE patterns are consistent with evolution by crystal fractionation of similar parental magmas. Thus, Anatahan is a type example of an island-arc volcano that erupts comagmatic basalts to dacites, with no evidence for crustal assimilation. The parental magmas to Anatahan lie at the low 143Nd/ 144Nd, Ba/La, and Sm/La end of the spectrum of magmas erupted in the Marianas arc, consistent with 1-3 wt.% addition of subducted sediment to the mantle source, or

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

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

  13. 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

  14. Volcanoes!

    USGS Publications Warehouse

    ,

    1997-01-01

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

  15. Reconstructing palaeo-volcanic geometries using a Geodynamic Regression Model (GRM): Application to Deception Island volcano (South Shetland Islands, Antarctica)

    NASA Astrophysics Data System (ADS)

    Torrecillas, C.; Berrocoso, M.; Felpeto, A.; Torrecillas, M. D.; Garcia, A.

    2013-01-01

    This article describes a reconstruction made of the palaeo-volcanic edifice on Deception Island (South Shetland Islands, Antarctica) prior to the formation of its present caldera. Deception Island is an active Quaternary volcano located in the Bransfield Strait, between the South Shetland Islands and the Antarctic Peninsula. The morphology of the island has been influenced mainly by the volcanic activity but geodynamics and volcanic deformation have also contributed. A volcanic reconstruction method, the Geodynamic Regression Model (GRM), which includes a terrain deformation factor, is proposed. In the case of Deception Island, the directions of this deformation are NW-SE and NE-SW, and match both the observed deformation of the Bransfield Strait and the volcanic deformation monitored over the last 20 years in the island, using Global Navigation Satellite System (GNSS) techniques. Based on these data, possible volcanic deformation values of 5-15 mm/yr in these directions have been derived. A possible coastline derived from a current bathymetry is transformed, according to values for the chosen date, to obtain the palaeo-coastline of Deception Island of 100 k years ago. Topographic, geomorphologic, volcanological and geological data in a GIS system have been considered, for computation of the outside caldera slope, palaeo-coastline, palaeo-summit height and palaeo digital elevation model (DEM). The result is a 3D palaeo-geomorphological surface model of a volcano, reaching 640 m in height, with an increase of 4 km3 in volume compared to the current edifice, covering 4 km2 more surface area and the method reveals the previous existence of parasite volcanoes. Two photorealistic images of the island are obtained by superposition of textures extracted from a current Quick Bird satellite image also. This technique for reconstructing the terrain of an existing volcano could be useful for analysing the past and future geomorphology of this island and similar locations.

  16. Origin of Japanese White-Eyes and Brown-Eared Bulbuls on the Volcano Islands.

    PubMed

    Sugita, Norimasa; Kawakami, Kazuto; Nishiumi, Isao

    2016-04-01

    The Ogasawara Archipelago comprises two groups of oceanic islands: the Bonin Islands, formed in the Paleogene, and the Volcano Islands, formed in the Quaternary. These groups are located within a moderate distance (ca. 160-270 km) of one another; thus, most land bird species are not distinguished as different subspecies. Two land birds, however, show unusual distribution. The Japanese white-eyes Zosterops japonicus originally inhabited only the Volcano Islands, but has been introduced to the Bonin Islands. The brown-eared bulbuls Hypsipetes amaurotis are distributed as a different subspecies. We investigated their genetic differences and divergences in the Ogasawara Archipelago using mitochondria DNA. The Volcano population of white-eyes had four endemic haplotypes that were divergent from one another, except for the Bonin population, which shared three haplotypes with the Volcano, Izu, and Ryukyu Islands and did not have any endemic haplotype. This is the first genetic suggestion that the Bonin population is a hybrid of introduced populations. With respect to bulbuls, the Volcano and Bonin Islands each had a single endemic haplotype. The Volcano haplotype is closest to a haplotype shared with Izu, the Japanese mainland, Daito and Ryukyu, whereas the Bonin haplotype is closest to one endemic to the south Ryukyu Islands. This indicates that the sources of the two bulbul populations can be geologically and temporally distinguished. The populations of the two species in the Ogasawara Archipelago are irreplaceable, owing to their genetic differences and should be regarded as evolutionarily significant units. In order to prevent introgression between the two populations, we must restrict interisland transfers.

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

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

  19. 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

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

    PubMed

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

    2014-01-02

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Sanchez, L.; González, 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.

  3. 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)

  4. Cyclic Explosivity in High Elevation Phreatomagmatic Eruptions at Ocean Island Volcanoes: Implications for Aquifer Pressurization and Volcano Flank Destabilization.

    NASA Astrophysics Data System (ADS)

    Tarff, R.; Day, S. J.; Downes, H.; Seghedi, I.

    2015-12-01

    Groundwater heating and pressurization of aquifers trapped between dikes in ocean island volcanoes has been proposed as a mechanism for destabilizing and triggering large-volume flank collapses. Previous modelling has indicated that heat transfer from sustained magma flow through dikes during eruption has the potential to produce destabilizing levels of pressure on time scales of 4 to 400 days, if the aquifers remain confined. Here we revisit this proposal from a different perspective. We examine evidence for pressure variations in dike-confined aquifers during eruptions at high elevation vents on ocean island volcanoes. Initially magmatic, these eruptions change to mostly small-volume explosive phreatomagmatic activity. A recent example is the 1949 eruption on La Palma, Canary Islands. Some such eruptions involve sequences of larger-volume explosive phases or cycles, including production of voluminous low-temperature, pyroclastic density currents (PDC). Here we present and interpret data from the Cova de Paul crater eruption (Santo Antao, Cape Verde Islands). The phreatomagmatic part of this eruption formed two cycles, each culminating with eruption of PDCs. Compositional and textural variations in the products of both cycles indicate that the diatreme fill began as coarse-grained and permeable which allowed gas to escape. During the eruption, the fill evolved to a finer grained, poorly sorted, less permeable material, in which pore fluid pressures built up to produce violent explosive phases. This implies that aquifers adjacent to the feeder intrusion were not simply depressurized at the onset of phreatomagmatic explosivity but experienced fluctuations in pressure throughout the eruption as the vent repeatedly choked and emptied. In combination with fluctuations in magma supply rate, driving of aquifer pressurization by cyclical vent choking will further complicate the prediction of flank destabilization during comparable eruptions on ocean island volcanoes.

  5. Moving towards Universal Health Coverage through the Development of Integrated Service Delivery Packages for Primary Health Care in the Solomon Islands

    PubMed Central

    Whiting, Stephen; Postma, Sjoerd; Jamshaid de Lorenzo, Ayesha; Aumua, Audrey

    2016-01-01

    The Solomon Islands Government is pursuing integrated care with the goal of improving the quality of health service delivery to rural populations. Under the auspices of Universal Health Coverage, integrated service delivery packages were developed which defined the clinical and public health services that should be provided at different levels of the health system. The process of developing integrated service delivery packages helped to identify key policy decisions the government needed to make in order to improve service quality and efficiency. The integrated service delivery packages have instigated the revision of job descriptions and are feeding into the development of a human resource plan for health. They are also being used to guide infrastructure development and health system planning and should lead to better management of resources. The integrated service delivery packages have become a key tool to operationalise the government’s policy to move towards a more efficient, equitable, quality and sustainable health system. PMID:28321177

  6. Comparative study of two tsunamigenic earthquakes in the Solomon Islands: 2015 Mw 7.0 normal-fault and 2013 Santa Cruz Mw 8.0 megathrust earthquakes

    NASA Astrophysics Data System (ADS)

    Heidarzadeh, Mohammad; Harada, Tomoya; Satake, Kenji; Ishibe, Takeo; Gusman, Aditya Riadi

    2016-05-01

    The July 2015 Mw 7.0 Solomon Islands tsunamigenic earthquake occurred ~40 km north of the February 2013 Mw 8.0 Santa Cruz earthquake. The proximity of the two epicenters provided unique opportunities for a comparative study of their source mechanisms and tsunami generation. The 2013 earthquake was an interplate event having a thrust focal mechanism at a depth of 30 km while the 2015 event was a normal-fault earthquake occurring at a shallow depth of 10 km in the overriding Pacific Plate. A combined use of tsunami and teleseismic data from the 2015 event revealed the north dipping fault plane and a rupture velocity of 3.6 km/s. Stress transfer analysis revealed that the 2015 earthquake occurred in a region with increased Coulomb stress following the 2013 earthquake. Spectral deconvolution, assuming the 2015 tsunami as empirical Green's function, indicated the source periods of the 2013 Santa Cruz tsunami as 10 and 22 min.

  7. 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)

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

  11. 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).

  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. Low Prevalence of Conjunctival Infection with Chlamydia trachomatis in a Treatment-Naïve Trachoma-Endemic Region of the Solomon Islands

    PubMed Central

    Butcher, Robert M. R.; Sokana, Oliver; Jack, Kelvin; Macleod, Colin K.; Marks, Michael E.; Kalae, Eric; Sui, Leslie; Russell, Charles; Tutill, Helena J.; Williams, Rachel J.; Breuer, Judith; Willis, Rebecca; Le Mesurier, Richard T.; Mabey, David C. W.; Solomon, Anthony W.; Roberts, Chrissy h.

    2016-01-01

    Background Trachoma is endemic in several Pacific Island states. Recent surveys across the Solomon Islands indicated that whilst trachomatous inflammation—follicular (TF) was present at levels warranting intervention, the prevalence of trachomatous trichiasis (TT) was low. We set out to determine the relationship between chlamydial infection and trachoma in this population. Methods We conducted a population-based trachoma prevalence survey of 3674 individuals from two Solomon Islands provinces. Participants were examined for clinical signs of trachoma. Conjunctival swabs were collected from all children aged 1–9 years. We tested swabs for Chlamydia trachomatis (Ct) DNA using droplet digital PCR. Chlamydial DNA from positive swabs was enriched and sequenced for use in phylogenetic analysis. Results We observed a moderate prevalence of TF in children aged 1–9 years (n = 296/1135, 26.1%) but low prevalence of trachomatous inflammation—intense (TI) (n = 2/1135, 0.2%) and current Ct infection (n = 13/1002, 1.3%) in children aged 1–9 years, and TT in those aged 15+ years (n = 2/2061, 0.1%). Ten of 13 (76.9%) cases of infection were in persons with TF or TI (p = 0.0005). Sequence analysis of the Ct-positive samples yielded 5/13 (38%) complete (>95% coverage of reference) genome sequences, and 8/13 complete plasmid sequences. Complete sequences all aligned most closely to ocular serovar reference strains. Discussion The low prevalence of TT, TI and Ct infection that we observed are incongruent with the high proportion of children exhibiting signs of TF. TF is present at levels that apparently warrant intervention, but the scarcity of other signs of trachoma indicates the phenotype is mild and may not pose a significant public health threat. Our data suggest that, whilst conjunctival Ct infection appears to be present in the region, it is present at levels that are unlikely to be the dominant driving force for TF in the population. This could be one reason for the

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

    NASA Astrophysics Data System (ADS)

    Klügel, Andreas; Longpré, Marc-Antoine; García-Cañada, Laura; Stix, John

    2015-12-01

    Oceanic intraplate volcanoes grow by accumulation of erupted material as well as by coeval or discrete magmatic intrusions. Dykes and other intrusive bodies within volcanic edifices are comparatively well studied, but intrusive processes deep beneath the volcanoes remain elusive. Although there is geological evidence for deep magmatic intrusions contributing to volcano growth through uplift, this has rarely been demonstrated by real-time monitoring. Here we use geophysical and petrological data from El Hierro, Canary Islands, to show that intrusions from the mantle and subhorizontal transport of magma within the oceanic crust result in rapid endogenous island growth. Seismicity and ground deformation associated with a submarine eruption in 2011-2012 reveal deep 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

  15. 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

  16. Enhanced syndromic surveillance for mass gatherings in the Pacific: a case study of the 11th Festival of Pacific Arts in Solomon Islands, 2012

    PubMed Central

    Hoy, Damian; Saketa, Salanieta T; Maraka, Roy Roger; Sio, Alison; Wanyeki, Ian; Frison, Pascal; Ogaoga, Divi; Iniakawala, Dennie; Joshua, Cynthia; Duituturaga, Sala; Lepers, Christelle; Roth, Adam; White, Paul; Souares, Yvan

    2016-01-01

    Mass gatherings pose public health challenges to host countries, as they can cause or exacerbate disease outbreaks within the host location or elsewhere. In July 2012, the 11th Festival of Pacific Arts (FOPA), a mass gathering event involving 22 Pacific island states and territories, was hosted by Solomon Islands. An enhanced syndromic surveillance (ESS) system was implemented for the event. Throughout the capital city, Honiara, 15 sentinel sites were established and successfully took part in the ESS system, which commenced one week before the FOPA (25 June) and concluded eight days after the event (22 July). The ESS involved expanding on the existing syndromic surveillance parameters: from one to 15 sentinel sites, from four to eight syndromes, from aggregated to case-based reporting and from weekly to daily reporting. A web-based system was developed to enable data entry, data storage and data analysis. Towards the end of the ESS period, a focus group discussion and series of key informant interviews were conducted. The ESS was considered a success and played an important role in the early detection of possible outbreaks. For the period of the ESS, 1668 patients with syndrome presentations were received across the 15 sentinel sites. There were no major events of public health significance. Several lessons were learnt that are relevant to ESS in mass gathering scenarios, including the importance of having adequate lead in time for engagement and preparation to ensure appropriate policy and institutional frameworks are put in place. PMID:27766181

  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.; 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. 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

  20. Influence of environmental factors on the abundance of Anopheles farauti larvae in large brackish water streams in Northern Guadalcanal, Solomon Islands

    PubMed Central

    2011-01-01

    Background The main vector of malaria in Solomon Islands is Anopheles farauti, which has a mainly coastal distribution. In Northern Guadalcanal, Solomon Islands, high densities of An. farauti are supported by large brackish streams, which in the dry season are dammed by localized sand migration. The factors controlling the high larval productivity of these breeding sites have not been identified. Accordingly the influence of environmental factors on the presence and density of An. farauti larvae was assessed in three large naturally dammed streams. Methods Larval sites were mapped and anopheline larvae were collected monthly for 12 months (July 2007 to June 2008) from three streams using standard dippers. Larval collections were made from 10 locations spaced at 50 m intervals along the edge of each stream starting from the coast. At each collection point, floating filamentous algae, aquatic emergent plants, sun exposure, and salinity were measured. These environmental parameters along with rainfall were correlated with larval presence and density. Results The presence and abundance of An. farauti larvae varied between streams and was influenced by the month of collection, and distance from the ocean (p < 0.001). Larvae were more frequently present and more abundant within 50 m of the ocean during the dry season when the streams were dammed. The presence and density of larvae were positively associated with aquatic emergent plants (presence: p = 0.049; density: p = 0.001). Although filamentous algae did not influence the presence of larvae, this factor did significantly influence the density of larvae (p < 0.001). Rainfall for the month prior to sampling was negatively associated with both larval presence and abundance (p < 0.001), as high rainfall flushed larvae from the streams. Salinity significantly influenced both the presence (p = 0.002) and density (p = 0.014) of larvae, with larvae being most present and abundant in brackish water at < 10‰ seawater

  1. 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

  2. Seismicity at White Island volcano, New Zealand: a revised classification and inferences about source mechanism

    NASA Astrophysics Data System (ADS)

    Sherburn, Steven; Scott, Bradley J.; Nishi, Yuji; Sugihara, Mituhiko

    1998-08-01

    The classification of earthquakes at White Island volcano, New Zealand, has been revised to address problems in existing classification schemes, to better reflect new data and to try to focus more on source processes. Seismicity generated by the direct involvement of magmatic or hydrothermal fluids are referred to as volcanic, and that generated by fault movement in response to stresses caused by those fluids, regional stresses, thermal effects and so on are referred to as volcano-tectonic. Spasmodic bursts form a separate category, as we have insufficient information to classify them as volcanic or volcano-tectonic. Volcanic seismicity is divided into short-duration, long-period volcanic earthquakes, long-duration volcanic earthquakes, and harmonic- and non-harmonic volcanic tremor, while volcano-tectonic seismicity is divided into shallow and deep volcano-tectonic earthquakes. Harmonic volcanic tremor is related to sub-surface intrusive processes, while non-harmonic volcanic tremor originates close to active craters at shallow depth, and usually occurs during eruptive activity. Short-duration, long-period volcanic earthquakes come from a single source close to the active craters, but originate deeper than non-harmonic volcanic tremor, and are not related to eruptive activity. Long-duration volcanic earthquakes often accompany larger discrete eruptions. The waveform of these events consists of an initial low-frequency part from a deep source, and a later cigar-shaped part of mixed frequencies from a shallow crater source.

  3. 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.

  4. Volcanoes

    MedlinePlus

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

  5. Volcanoes

    USGS Publications Warehouse

    Tilling, Robert I.

    1998-01-01

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

  6. The 2003 phreatomagmatic eruptions of Anatahan volcano - Textural and petrologic features of deposits at an emergent island volcano

    USGS Publications Warehouse

    Pallister, J.S.; Trusdell, F.A.; Brownfield, I.K.; Siems, D.F.; Budahn, J.R.; Sutley, S.F.

    2005-01-01

    Stratigraphic and field data are used in conjunction with textural and chemical evidence (including data from scanning electron microscope, electron microprobe, X-ray fluorescence, X-ray diffraction, and instrumental neutron activation analysis) to establish that the 2003 eruption of Anatahan volcano was mainly phreatomagmatic, dominated by explosive interaction of homogeneous composition low-viscosity crystal-poor andesite magma with water. The hydromagmatic mode of eruption contributed to the significant height of initial eruptive columns and to the excavation and eruption of altered rock debris from the sub-volcanic hydrothermal system. Volatile contents of glass inclusions in equilibrium phenocrysts less abundances of these constituents in matrix glass times the estimated mass of juvenile magma indicate minimum emissions of 19 kt SO2 and 13 kt Cl. This petrologic estimate of SO2 emission is an order-of-magnitude less than an estimate from TOMS. Similarly, inferred magma volumes from the petrologic data are an order of magnitude greater than those modeled from deformation data. Both discrepancies indicate additional sources of volatiles, likely derived from a separate fluid phase in the magma. The paucity of near-source volcanic-tectonic earthquakes preceding the eruption, and the dominance of sustained long-period tremor are attributed to the ease of ascent of the hot low-viscosity andesite, followed by a shallow phreatomagmatic mode of eruption. Phreatomagmatic eruptions are probably more common at emergent tropical island volcanoes, where shallow fresh-water lenses occur at near-sea-level vents. These relations suggest that phreatomagmatic explosions contributed to the formation of many of the near-sea-level craters and possibly even to the small calderas at the other Mariana islands.

  7. Counterinsurgency in a Test Tube. Analyzing the Success of the Regional Assistance Mission to Solomon Islands (RAMSI)

    DTIC Science & Technology

    2007-01-01

    form, any of our research documents. Limited Electronic Distribution Rights Visit RAND at www.rand.org Explore RAND National Defense Research...was done. The Big Three maintained a routine of extensive travel from the start, visiting villages throughout the islands to communicate their...spread word of their arrival and its objectives throughout the islands by way of visits to hundreds of villages and towns and through radio and

  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.

  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. A new genus with two new species of lecanicephalidean tapeworms (Cestoda) from the mangrove whipray, Urogymnus granulatus (Myliobatiformes: Dasyatidae),from the Solomon Islands and northern Australia.

    PubMed

    Herzog, Kaylee S; Jensen, Kirsten

    2017-02-06

    A new lecanicephalidean genus is erected for cestodes previously recognised as "New Genus 12" (Polypocephalidae) in a phylogenetic analysis of the interrelationship of members of this order. Examination of the cestode fauna of the mangrove whipray, Urogymnus granulatus (Macleay) (Myliobatiformes: Dasyatidae) from the Solomon Islands and northern Australia revealed the existence of specimens representing two new species, consistent in morphology with "New Genus 12." Corollapex gen. n. is unique among the 24 valid lecanicephalidean genera in its possession of an apical organ in the form of an external retractable central disk surrounded by eight concave muscular, membrane-bound pads and an internal heterogeneous glandular component. The two new species described herein, Corollapex cairae sp. n. (type species) and Corollapex tingoi sp. n., differ from one another in overall size and number of mature and immature proglottids, and are noted to demonstrate a differential distribution between mature and juvenile host individuals. Additional species diversity in the new genus, beyond C. cairae sp. n., C. tingoi sp. n., and "New Genus 12 n. sp. 1" of Jensen et al. (2016) is suggested. Corollapex gen. n. appears to be restricted to dasyatid hosts in the Indo-West Pacific region.

  11. 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.

  12. 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

  13. 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 Niño-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, 8°07.92' S, 156°54.50' 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 δ18O, between both monthly (r = 0.84) and monthly anomaly (r = 0.69) records. These results demonstrate that the Olasana D. heliopora coral δ18O record is a robust proxy of local surface ocean conditions. There is also a robust relationship between the Olasana δ18O record and NINO3.4 index of ENSO activity during 1938-2007, which provides confidence that the Olasana δ18O 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).

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1984-05-01

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

  16. Geophysical monitoring from seafloor observatories in Italian volcanic sites: Marsili Seamount, Etna Volcano and Stromboli Island.

    NASA Astrophysics Data System (ADS)

    Giovanetti, Gabriele; Monna, Stephen; Lo Bue, Nadia; Embriaco, Davide; Frugoni, Francesco; Marinaro, Giuditta; De Caro, Mariagrazia; Sgroi, Tiziana; Montuori, Caterina; De Santis, Angelo; Cianchini, Gianfranco; Favali, Paolo; Beranzoli, Laura

    2016-04-01

    Many volcanoes on Earth are located within or near the oceans and observations from the seafloor can be very important for a more complete understanding of the structure and nature of these volcanoes. We present some results obtained from data acquired in volcanic sites in the Central Mediterranean Sea. Data were taken by means of stand-alone free-fall systems, and fixed-point ocean observatories, both cabled and autonomous, some of which are part of the European research infrastructure EMSO (European Multidisciplinary Seafloor and water-column Observatory, www.emso-eu.org). EMSO observatories strongly rely on a multidisciplinary approach, in spite of the many technical challenges that the operation of very different sensors by means of a single acquisition system presents. We focus on three volcanic sites near the coasts of Italy (Marsili seamount, Stromboli Island and Etna Volcano) involved in subduction processes and to the opening of the Central Mediterranean basin. Through multidisciplinary analysis we were able to associate geophysical and oceanographic signals to a common volcanic source in a more reliable way with respect to single sensor analysis, showing the potential of long-term seafloor monitoring in unravelling otherwise still obscure aspects of such volcanoes. The very strong expansion of seafloor monitoring, which is taking place both in the quantity of the infrastructures and in the technological capabilities, suggests that there will be important developments in the near future.

  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. Numerical Modeling of Sound from the Eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Park, M.; Dziak, R. P.; Byun, S.; Fox, C. G.; Matsumoto, H.

    2003-12-01

    NOAA VENTS Program deployed an array of five autonomous underwater hydrophones within the SOFAR channel along the Mariana chain in February 2003 to monitor seafloor volcanic eruptions and submarine earthquakes (sponsored by NOAA's Ocean Exploration Program). These five hydrophones will be recovered in September 2003 using KORDI R/V Onnuri. The first historical eruption of Anatahan volcano in the Mariana Islands began on 10 May 2003. It is expected that the hydrophone data will include the hydroacoustic records of the eruption of Anatahan Volcano. The signals recorded from the eruption will be numerically modeled using a T-wave excitation mechanism developed from the mode scattering theory of Park et al. (2001). They found that scattering from the rough seabottom converts the acoustic energy of seafloor earthquakes from the directly excited ocean crustal/water column modes to the propagating acoustic modes of T-waves, and developed an algorithm to numerically model oceanic earthquake's T-waves. We modified this numerical model of Park et al. (2001) to predict the T-waves generated from volcanic sources by adopting a buried magmatic pipe model (Chouet, 1985). We derived a moment-tensor representation of a volcano-seismic source that is governed by the geometry of the source and the physical properties of magma. Numerical modeling of the sound from the eruption requires us to determine governing factors such as the pipe radius and magma viscosity that will enable us to grasp the inward nature of Anatahan volcano.

  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

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu

    2014-12-01

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

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

    USGS Publications Warehouse

    Williams, R.S.; 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.

  3. 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.

  4. 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

    2015-08-26

    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.

  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 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

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

    NASA Astrophysics Data System (ADS)

    Mazot, A.; Bernard, A.

    2003-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  9. 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.

  10. 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

  11. 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

    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.

  12. Rapid thermal rejuvenation of high-crystallinity magma linked to porphyry copper deposit formation; evidence from the Koloula Porphyry Prospect, Solomon Islands

    NASA Astrophysics Data System (ADS)

    Tapster, S.; Condon, D. J.; Naden, J.; Noble, S. R.; Petterson, M. G.; Roberts, N. M. W.; Saunders, A. D.; Smith, D. J.

    2016-05-01

    Magmas containing the components needed to form porphyry copper deposits are relatively common within arcs, yet mineralising events are uncommon within the long-lived magmatic systems that host them. Understanding what causes the transition from barren to productive intrusions is critical to the development of conceptual deposit models. We have constrained the tempo of pre- and syn-mineralisation magmatic events in relationship to the thermal evolution of the plutonic body that underlies one of the world's youngest exposed plutonic-porphyry systems, the Inamumu Zoned Pluton, Koloula Porphyry Prospect, Solomon Islands. High precision ID-TIMS U-Pb dates of texturally and chemically characterised zircons indicate pluton emplacement over <150 kyr was superseded after ca. 50 kyr by two discrete episodes of mineralising porphyritic melt emplacement. Their associated hydrothermal systems initiated within ca. 30 kyrs of each other. Zircon populations within evolved intrusions contain resorbed cores that were recycled from the deeper magmatic system, yet their youngest dates are statistically indistinguishable from those yielded by crystals lacking resorption. Comparisons of Ti-in-zircon proxy temperatures, modelled zircon saturation temperatures and temperature-crystallinity relationships suggest that prior to being heated and emplaced within the shallow level pluton, magmas were stored at depth in a high-crystallinity (>50% crystals) state, past the point of rheological lock-up. We estimate that thermal rejuvenation of the deeper high-crystallinity magma and generation of a mobile melt fraction may have occurred ≤10 kyr before its transport and emplacement within the porphyry environment. The underlying pluton likely cooled and returned to high-crystallinity states prior to subsequent remobilisation-emplacement events. Titanium-in-zircon geothermometry and whole-rock geochemistry suggest pre-mineralisation intrusions were remobilised by mixing of a silicic magma with a

  13. 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

  14. Geochemical Composition of Volcanic Rocks from the May 2003 Eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Wade, J. A.; Plank, T.; Stern, R.; Hilton, D.; Fischer, T. P.; Moore, R.; Trusdell, F.; Sako, M.

    2003-12-01

    The first historical eruption of Anatahan volcano began on May 10, 2003, from the easternmost of the island's two craters. Samples of tephra, scoria, and bombs, collected in May by a MARGINS-supported rapid-response team, were analyzed for 34 trace elements by solution ICP-MS at Boston University and Sr-Nd-Pb isotopic composition at the University of Texas-Dallas. The new eruptive materials can be compared with an extensive suite of pre-existing volcanics (basalts through dacites) from Anatahan sampled by the USGS in 1990 and 1992, and analyzed by XRF and INAA. While most Mariana volcanoes erupt basalts and basaltic andesites, Anatahan is unusual for erupting a wide range of compositions, from basalt to dacite, and thus provides the best opportunity for addressing questions of magma evolution in this classic island arc. The newly erupted scoria and pumice are andesites and dacites that are among the most silicic materials erupted in the northern Mariana islands. The recent eruptives are highly homogeneous; 13 samples vary by only 3-5% relative standard deviation for incompatible trace elements. Isotopic compositions (0.703450 +/- 2 87Sr/86Sr and 18.806 +/- 5 206Pb/204Pb) are within the range of previously measured samples from Anatahan and other volcanic centers in the Marianas. The combined dataset for Anatahan defines virtually a single liquid line of descent. This is consistent with nearly-parallel REE patterns, and small variations in the ratios of the most incompatible trace elements (e.g., Th/Rb varies by <10% over the entire fractionation trend). Low values of Th/La and Th/Zr in Anatahan volcanics provide evidence against partial melting of crustal material as a source of the silicic magmas, as these ratios are highly senstive to apatite- and zircon- saturated crustal melts. Instead, the basalts, andesites and dacites of Anatahan appear to be related predominantly by crystal fractionation with little evidence for assimilation of crustal melts. The new data

  15. 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

  16. 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.

  17. 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.

  18. Dismantling processes of basaltic shield volcanoes - origin of the Piton des Neiges breccias - Reunion Island

    NASA Astrophysics Data System (ADS)

    Arnaud, A.; Bachèlery, B.; Cruchet, C.

    2003-04-01

    Reunion Island is mainly composed by two volcanic massifs: the active Piton de la Fournaise to the southeast and the Piton des Neiges to the northwest that has been inactive for about 12000 years. The latter corresponds to a dismantled volcanic massif, deeply cut by valleys and by three vast depressions, called “cirques” around the centre of the volcano. They offer the opportunity to observe the inside of a basaltic shield volcano. The first work dealing with the origin of the “cirques” very quickly showed the existence of a significant cover of breccia deposits. These breccias were often interpreted as the result of a major stage of erosion considered as partly at the origin of the “cirques” formation. Geological campaigns mainly achieved in the “cirque de Salazie” (eastern of the Piton des Neiges), allow to establish a first typology based on morphological, phenomenological and sedimentary features of the deposits. Two main complexes of breccias have been distinguished. An old complex outcropping in the internal parts of the cirque and an upper complex generally overlaying the lower complex. The old complex comprises two main units of breccias. These units show a strong alteration marked by the presence of clays, chlorites, serpentines and zeolites. In the inner part of the cirque, these breccias are closely related to the old lava formations from which they come. These units show frequent jigsaw-cracks, a chaotic stratigraphy, as well as large amounts of chlorite. The upper complex is constituted by four main units which are more or less geographically separated in the cirque of Salazie. Their limits are not yet well identified because of the significant relief and a strong vegetable cover. Several units display a very strong fracturation, jigsaw-cracks and a chaotic stratigraphy whereas many lava flows are pulverised and locally injected in scoria levels. Recent work on Saint-Gilles breccias (Fèvre et al., this meeting) allowed to identify

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

    USGS Publications Warehouse

    Rybin, A.; Chibisova, M.; Webley, P.; Steensen, T.; Izbekov, P.; Neal, C.; Realmuto, V.

    2011-01-01

    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. ?? 2011 Springer-Verlag.

  20. The 2008 phreatomagmatic eruption of Okmok volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes

    USGS Publications Warehouse

    Jessica Larsen,; Neal, Christina; Schaefer, Janet R.; Kaufman, Max; Lu, Zhong

    2015-01-01

    Okmok volcano, Aleutian Islands, Alaska, explosively erupted over a five-week period between July 12 and August 23, 2008. The eruption was predominantly phreatomagmatic, producing fine-grained tephra that covered most of northeastern Umnak Island. The eruption had a maximum Volcanic Explosivity Index (VEI) of 4, with eruption column heights up to 16 km during the opening phase. Several craters and a master tuff cone formed in the caldera as a result of phreatomagmatic explosions and accumulated tephra-fall and surge deposits. Ascending magma continuously interacted with an extensive shallow groundwater table in the caldera, resulting in the phreatomagmatic character of the eruption. Syneruptive explosion and collapse processes enlarged a pre-existing lake, created a second, entirely new lake, and formed new, deep craters. A field of ephemeral collapse pits and collapse escarpments formed where rapid groundwater withdrawal removed material from beneath capping lava flows. This was the first significant phreatomagmatic event in the U.S. since the Ukinrek Maars eruption in 1977.

  1. Geological aspects of the 2003 2004 eruption of Anatahan Volcano, Northern Mariana Islands

    NASA Astrophysics Data System (ADS)

    Nakada, Setsuya; Matsushima, Takeshi; Yoshimoto, Mitsuhiro; Sugimoto, Takeshi; Kato, Teruyuki; Watanabe, Tsuyoshi; Chong, Ramon; Camacho, Juan T.

    2005-08-01

    Anatahan Volcano, Northern Mariana Islands, began erupting in May-June 2003. A series of subplinian explosive eruptions of andesite magma began at the Eastern Crater in the eastern part of the summit caldera on the evening of 10 May. Brown tephra was sent mainly westward by strong winds. Small-scale pyroclastic surges were discharged eastward outside the caldera in late May. An andesite lava dome that had once filled the inner crater was fragmented by phreatomagmatic explosions in the middle of June. The phreatomagmatic explosions probably occurred due to interaction of the magma head with groundwater around the crater, and abundant very fine ash ("gray tephra") was discharged within the caldera and over most of the island. The volume of eruption products of the May-June eruption was estimated to be 1.4 × 10 7 m 3 dense-rock-equivalent. Erupted pumices and lava are aphyric andesite and are variously colored depending on their vesicularity. The SiO 2 contents of erupted materials decreased slightly with time. The fine gray ash is depleted in alkalies, probably due to leaching by acid hydrothermal fluids during explosions. Seismic activity resumed in late March 2004, and small strombolian-like explosions were repeated in May and June 2004. About half of the inner crater was filled with new scoria and lava.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Ibáñez, 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

  4. Geology, geochronology and geochemistry of a basanitic volcano, White Island, Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Cooper, Alan F.; Adam, Lotte J.; Coulter, Roseanne F.; Eby, G. Nelson; McIntosh, William C.

    2007-09-01

    White Island, Ross Sea, Antarctica is a Plio-Pleistocene basanite to tephriphonolite shield volcano, forming part of the Erebus Province, McMurdo Volcanic Group. Four new 40Ar/ 39Ar dates extend the age of surface volcanism from a previously determined 0.17 Ma to 5.05 ± 0.31 Ma. A U/Pb age on zircon in an anorthoclasite nodule extends White Island magmatism back to 7.65 ± 0.69 Ma. Volcanism was predominantly subaerial with eruption of agglutinated spatter-clast breccias and lava flows from vents with a NNE structural alignment. An early phase of inferred subaqueous/subglacial activity formed pillow breccias. Two nunataks in the southern part of the island comprise basanitic tuff cones, composed of poorly bedded pyroclastic deposits dominated by sideromelane lapilli, and containing horizons rich in accretionary and armoured lapilli. Many of the basanites have compositions of near-primary magmas and contain an assortment of Cr-diopside and Al-augite suite mantle nodules, lower crustal gabbros, mafic granulites, and assorted megacrysts. Peridotites are dominated by spinel facies inclusions, but include plagioclase-spinel lherzolites derived from shallow mantle beneath the tectonically thinned and attenuated Ross Sea lithosphere. Mantle nodules contain accessory amounts of pale brown, metasomatic amphibole. Volcanic geochemistry is compatible with fractionation of olivine, pyroxene, titano-magnetite and minor apatite from a basanite parent yielding tephriphonolite residual liquids. Magmatism is focused along, or at the termination of, Cenozoic rift basins in the Ross Sea. The regional McMurdo Volcanic Group distribution and tectonic setting, and the history of Erebus Province volcanic centres are difficult to reconcile in terms of active mantle plumes. Instead, more randomly distributed magmatism is inferred to result from rift-related decompression melting of previously enriched mantle that may have been fertilized by plume interaction prior to Gondwana

  5. 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

  6. A new species of pea crab of the genus Serenotheres Ahyong & Ng, 2005 (Crustacea, Brachyura, Pinnotheridae) from the date mussel Leiosolenus Carpenter, 1857 (Mollusca, Bivalvia, Mytilidae, Lithophaginae) from the Solomon Islands.

    PubMed

    Ng, Peter K L; Meyer, Chistopher

    2016-01-01

    The pea crab genus Serenotheres Ahyong & Ng, 2005 (Pinnotheridae) is currently only represented by one species, Serenotheres besutensis (Serène, 1967). A new species is now assigned to this genus, described from a date mussel Leiosolenus obesus Carpenter, 1857 (Mollusca: Bivalvia: Mytilidae: Lithophaginae) collected in the Solomon Islands. Serenotheres janussp. n. differs from Serenotheres besutensis in possessing a conspicuously broader carapace, with the lateral margins of the dorsal lamellum distinctly produced and the posterolateral part deeply concave, the dorsal lamellum being highest at the median cleft, the rostrum is relatively more prominent, the surfaces of the anterolateral margin and hepatic region are less prominently pitted and eroded, the ischiomerus of the third maxilliped is relatively more rectangular, and the P2 merus is proportionately longer.

  7. A new species of pea crab of the genus Serenotheres Ahyong & Ng, 2005 (Crustacea, Brachyura, Pinnotheridae) from the date mussel Leiosolenus Carpenter, 1857 (Mollusca, Bivalvia, Mytilidae, Lithophaginae) from the Solomon Islands

    PubMed Central

    Ng, Peter K. L.; Meyer, Chistopher

    2016-01-01

    Abstract The pea crab genus Serenotheres Ahyong & Ng, 2005 (Pinnotheridae) is currently only represented by one species, Serenotheres besutensis (Serène, 1967). A new species is now assigned to this genus, described from a date mussel Leiosolenus obesus Carpenter, 1857 (Mollusca: Bivalvia: Mytilidae: Lithophaginae) collected in the Solomon Islands. Serenotheres janus sp. n. differs from Serenotheres besutensis in possessing a conspicuously broader carapace, with the lateral margins of the dorsal lamellum distinctly produced and the posterolateral part deeply concave, the dorsal lamellum being highest at the median cleft, the rostrum is relatively more prominent, the surfaces of the anterolateral margin and hepatic region are less prominently pitted and eroded, the ischiomerus of the third maxilliped is relatively more rectangular, and the P2 merus is proportionately longer. PMID:27843386

  8. 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.

  9. ENVISAT SAR and InSAR Observations of Deformation and Crater Floor Elevation Change of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Wicks, C.; Yarai, H.; Lu, Z.; Helz, R.

    2005-12-01

    Anatahan Volcano is a strato-volcano situated on a small 9 km by 3 km island in the Mariana Islands of the west Pacific Ocean. The volcano came to life with its first historical eruption in May 2003 ejecting a column of ash from the east crater up to 10 km into the atmosphere. The east crater is one of several craters that coalesce into a larger 5 km by 2 km caldera, the largest caldera in the volcanoes of the Mariana Islands. We will show results of a nascent InSAR study of Mariana volcanoes using European Space Agency (ESA) ENVISAT data. ESA began acquiring SAR data (IS2 and IS6 modes for both ascending and descending passes) over the Marianas Islands in November of 2004 at our request. Interferograms constructed from IS6 mode data display better coherence than those constructed from IS2 data. This coherence is reasonably well maintained from one acquisition to the next, and fairly well maintained over several months from Nov, 2004 to April, 2005. Limited explosive activity in late January and early February apparently did not destroy InSAR coherence through April 5. The largest of the eruptions, to date, occurred on April 5 (UT) about 12 hours after ESA acquired data over the island. Interferograms constructed using the April 5 image display a deformation field that is consistent with an inflating dike that trends SW from the east caldera to the south shore of the island. Since the April 5, 2005 eruption, there has been too much ash deposition and erosion to expect coherent interferograms for at least the near future. Because the inner walls of the east crater are steeper than the IS6 mode incident radar beams, which are incident about 40 degrees from vertical, we have used the change in radar shadow length to estimate the change in elevation of the crater floor. We found that the crater floor rose over 40 m between January 25 and March 1, 2005, and stayed at that level through the April 5 acquisition time. From this shadow length decrease, we have estimated a

  10. 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.

  11. Evidence of two Holocene phreatomagmatic eruptions at Stromboli volcano (Aeolian Islands) from paleomagnetic data

    NASA Astrophysics Data System (ADS)

    Porreca, M.; Giordano, G.; Mattei, M.; Musacchio, P.

    2006-11-01

    We present detailed stratigraphic-sedimentological and paleomagnetic analyses of Holocene phreatomagmatic deposits at Stromboli volcano (Aeolian Islands, Italy). The investigated deposits belong to the Secche di Lazzaro succession (SDL) and to the Advanced Operations Center of the Department of Civil Defense (COA) succession, both lying on the Neostromboli lavas (ca. 13-5 ka). The two stratigraphic successions have similar stratigraphic position and show a phreatomagmatic origin, likely related to catastrophic magma-water interaction processes during sector collapse events. However the thermal remanent magnetization data of the lava lithics indicate that deposits of the SDL succession were emplaced at very low temperatures (less than 140°C), whereas the basal part of the COA deposit was emplaced at temperatures between 300-340°C. Paleomagnetic results indicate that the two investigated deposits may be related to two distinct eruptive events occurred during the Holocene. Recent phreatomagmatic activity at Stromboli apparently has occurred more frequently than previously believed. Consequently, we must reconsider the recurrence interval of this dangerous eruptive scenario for Stromboli.

  12. 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…

  13. 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

  14. Morphology of Piton de la Fournaise basaltic shield volcano (La Réunion Island): Characterization and implication in the volcano evolution

    NASA Astrophysics Data System (ADS)

    Michon, Laurent; Saint-Ange, Francky

    2008-03-01

    The topography of Piton de la Fournaise volcano (PdF) differs from the classic view of basaltic shield volcanoes as it is characterized by (1) several steep slope zones on its flanks and (2) a large U-shaped caldera, the Enclos-Grand Brûlé structure (EGBS). Most of these structures were previously interpreted as the scars of lateral landslides, the deposits of which cover the submarine flanks of PdF. We carried out a detailed analysis of the morphology of PdF, which reveals that the steep slope zones form two independent, circumferential structures that continue into the caldera. The development of circumferential steep slopes on volcano flanks may have several origins: constructive, destructive, and deformation processes. We interpret those processes acting on PdF as caused by the spreading of the volcanic edifice above a weak hydrothermal core, leading to outward displacements and a summit extensive stress field. The continuity of the steep slope on both sides of the EGBS escarpments suggests that this structure was not caused by a 4.5 ka old giant landslide as it is usually proposed but is due to a mainly vertical collapse. The recent debris avalanche deposits east of the island indicate that this event likely destabilized part of the submarine flank. We propose that the collapse of the Grand Brûlé, the lower half of the EGBS, was due to the downward drag related to the dense intrusive complex of the Alizés volcano, which is located 1 km below the Grand Brûlé. The collapse of the Enclos is interpreted as the consequence of the deformation of the hydrothermal system of the pre-Enclos volcano. Although the continuity of the geological and morphological structures between the Enclos and the Grand Brûlé suggests a narrow link between these two collapse events, their chronology and relationship are still uncertain. Finally, we hypothesize that the persistence of the NE and SE rift zones during the last 150 ka, despite the large changes of the topography

  15. 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

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

    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.

  17. 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

  18. Variable SO2 emission rates for Anatahan volcano, the Commonwealth of the Northern Mariana Islands: Implications for deriving arc-wide volatile fluxes from erupting volcanoes

    NASA Astrophysics Data System (ADS)

    Hilton, D. R.; Fischer, T. P.; McGonigle, A. J. S.; de Moor, J. M.

    2007-07-01

    We report new spectroscopic-derived SO2 emission rates for Anatahan volcano, Mariana Islands. Measurements of SO2 fluxes reveal large fluctuations over the 2003-2005 period - from 78 kg s-1 which occurred on the same day as resurgent volcanic activity (March, 2005) to 50 kg s-1 and 25 kg s-1 made days/weeks after the start of eruptive sequences in 2003 and 2004 respectively. Even the lowest values make Anatahan a major global source of SO2 over the past decade. These SO2 emission rates are used to estimate the CO2 flux from the arc as a whole (=3.6 - 40 × 107 mol km-1 yr-1). Such values are significantly higher than estimates derived using other approaches: they are also high compared to other convergent margins (e.g., Central America) where the input flux of CO2 is substantially greater. Our results caution against including volatile fluxes from actively-degassing volcanoes to produce volatile outputs considered representative of entire arc fronts.

  19. High-frequency earthquakes at White Island volcano, New Zealand: insights into the shallow structure of a volcano-hydrothermal system

    NASA Astrophysics Data System (ADS)

    Nishi, Yuji; Sherburn, Steven; Scott, Bradley J.; Sugihara, Mituhiko

    1996-08-01

    Volcano-tectonic earthquakes at White Island are concentrated in a single seismically active zone, southeast of the active vents and at depths of less than 1 km. A few deeper earthquakes also occur beneath the active vents. A composite focal mechanism indicates that the stress regime in the shallow seismic zone is N-S extensional. Shallow seismicity occurs within the main volume of the volcano-hydrothermal system that underlies the Main Crater floor, and we interpret this as a region where the rocks have been weakened by past magmatic intrusions, elevated pore fluid pressure and physico-chemical effects of acid volcanic fluids, thereby allowing preferential seismic failure. Brittle seismic failure within this region requires a temperature less than about 400 °C, and implies high horizontal temperature gradients close to the active craters and fumaroles. Spasmodic bursts events are also a result of brittle failure, but occur close to zones of significant permeability in response to changes in local fluid pressure.

  20. 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

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

    NASA Astrophysics Data System (ADS)

    IbáñEz, Jesús M.; Pezzo, Edoardo Del; Almendros, Javier; La Rocca, Mario; Alguacil, Gerardo; Ortiz, Ramón; GarcíA, 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.

  2. 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

  3. Seismicity patterns during a period of inflation at Sierra Negra volcano, Galápagos Ocean Island Chain

    NASA Astrophysics Data System (ADS)

    Davidge, Lindsey; Ebinger, Cynthia; Ruiz, Mario; Tepp, Gabrielle; Amelung, Falk; Geist, Dennis; Coté, Dustin; Anzieta, Juan

    2017-03-01

    Basaltic shield volcanoes of the western Galápagos islands are among the most rapidly deforming volcanoes worldwide, but little was known of the internal structure and brittle deformation processes accompanying inflation and deflation cycles. A 15-station broadband seismic array was deployed on and surrounding Sierra Negra volcano, Galápagos from July 2009 through June 2011 to characterize seismic strain patterns during an inter-eruption inflation period and to evaluate single and layered magma chamber models for ocean island volcanoes. We compare precise earthquake locations determined from a 3D velocity model and from a double difference cluster method. Using first-motion of P-arrivals, we determine focal mechanisms for 8 of the largest earthquakes (ML ≤ 1.5) located within the array. Most of the 2382 earthquakes detected by the array occurred beneath the broad (∼9 km-wide) Sierra Negra caldera, at depths from surface to about 8 km below sea level. Although outside our array, frequent and larger magnitude (ML ≤ 3.4) earthquakes occurred at Alcedo and Fernandina volcano, and in a spatial cluster beneath the shallow marine platform between Fernandina and Sierra Negra volcanoes. The time-space relations and focal mechanism solutions from a 4-day long period of intense seismicity June 4-9, 2010 along the southeastern flank of Sierra Negra suggests that the upward-migrating earthquake swarm occurred during a small volume intrusion at depths 5-8 km subsurface, but there was no detectable signal in InSAR data to further constrain geometry and volume. Focal mechanisms of earthquakes beneath the steep intra-caldera faults and along the ring fault system are reverse and strike-slip. These new seismicity data integrated with tomographic, geodetic, and petrological models indicate a stratified magmatic plumbing system: a shallow sill beneath the large caldera that is supplied by magma from a large volume deeper feeding system. The large amplitude inter

  4. 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.; Fernández-Ros, A.; García, 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

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

    NASA Astrophysics Data System (ADS)

    Ibáñez, J. M.; Carmona, E.; Almendros, J.; Saccorotti, G.; del Pezzo, E.; Abril, M.; Ortiz, R.; Martínez-Arévalo, 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    PubMed

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

    2012-01-01

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

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

    PubMed Central

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

    2012-01-01

    On October 10 2011 an underwater eruption gave rise to a novel shallow submarine volcano south of the island of El Hierro, Canary Islands, Spain. During the eruption large quantities of mantle-derived gases, solutes and heat were released into the surrounding waters. In order to monitor the impact of the eruption on the marine ecosystem, periodic multidisciplinary cruises were carried out. Here, we present an initial report of the extreme physical-chemical perturbations caused by this event, comprising thermal changes, water acidification, deoxygenation and metal-enrichment, which resulted in significant alterations to the activity and composition of local plankton communities. Our findings highlight the potential role of this eruptive process as a natural ecosystem-scale experiment for the study of extreme effects of global change stressors on marine environments. PMID:22768379

  9. 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.

  10. Diffuse volcanic degassing and thermal energy release 2015 surveys from the summit cone of Teide volcano, Tenerife (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Melián, Gladys; Asensio-Ramos, María; Padilla, Germán; Alonso, Mar; Halliwell, Simon; Sharp, Emerson; Butters, Damaris; Ingman, Dylan; Alexander, Scott; Cook, Jenny; Pérez, Nemesio M.

    2016-04-01

    The summit cone of Teide volcano (Spain) is characterized by the presence of a weak fumarolic system, steamy ground, and high rates of diffuse CO2 degassing all around this area. The temperature of the fumaroles (83° C) corresponds to the boiling point of water at discharge conditions. Water is the major component of these fumarolic emissions, followed by CO2, N2, H2, H2S, HCl, Ar, CH4, He and CO, a composition typical of hydrothermal fluids. Previous diffuse CO2 surveys have shown to be an important tool to detect early warnings of possible impending volcanic unrests at Tenerife Island (Melián et al., 2012; Pérez et al., 2013). In July 2015, a soil and fumarole gas survey was undertaken in order to estimate the diffuse volcanic degassing and thermal energy release from the summit cone of Teide volcano. A diffuse CO2 emission survey was performed selecting 170 observation sites according to the accumulation chamber method. Soil CO2 efflux values range from non-detectable (˜0.5 g m-2d-1) up to 10,672 g m-2d-1, with an average value of 601 g m-2d-1. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. Measurement of soil CO2 efflux allowed an estimation of 162 ± 14 t d-1 of deep seated derived CO2. To calculate the steam discharge associated with this volcanic/hydrothermal CO2 output, we used the average H2O/CO2 mass ratio equal to 1.19 (range, 0.44-3.42) as a representative value of the H2O/CO2 mass ratios for Teide fumaroles. The resulting estimate of the steam flow associated with the gas flux is equal to 193 t d-1. The condensation of this steam results in a thermal energy release of 5.0×1011J d-1 for Teide volcano or a total heat flow of 6 MWt. The diffuse gas emissions and thermal energy released from the summit of Teide volcano are comparable to those observed at other volcanoes. Sustained surveillance using these methods will be valuable for monitoring the activity of Teide volcano.

  11. A Comparison of MODIS and DOAS Sulfur Dioxide Measurements of the April 24, 2004 Eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Meier, V. L.; Scuderi, L.; Fischer, T.; Realmuto, V.; Hilton, D.

    2006-12-01

    Measurements of volcanic SO2 emissions provide insight into the processes working below a volcano, which can presage volcanic events. Being able to measure SO2 in near real-time is invaluable for the planning and response of hazard mitigation teams. Currently, there are several methods used to quantify the SO2 output of degassing volcanoes. Ground and aerial-based measurements using the differential optical absorption spectrometer (mini-DOAS) provide real-time estimates of SO2 output. Satellite-based measurements, which can provide similar estimates in near real-time, have increasingly been used as a tool for volcanic monitoring. Direct Broadcast (DB) real-time processing of remotely sensed data from NASA's Earth Observing System (EOS) satellites (MODIS Terra and Aqua) presents volcanologists with a range of spectral bands and processing options for the study of volcanic emissions. While the spatial resolution of MODIS is 1 km in the Very Near Infrared (VNIR) and Thermal Infrared (TIR), a high temporal resolution and a wide range of radiance measurements in 32 channels between VNIR and TIR combine to provide a versatile space borne platform to monitor SO2 emissions from volcanoes. An important question remaining to be answered is how well do MODIS SO2 estimates compare with DOAS estimates? In 2004 ground-based plume measurements were collected on April 24th and 25th at Anatahan volcano in the Mariana Islands using a mini-DOAS (Fischer and Hilton). SO2 measurements for these same dates have also been calculated using MODIS images and SO2 mapping software (Realmuto). A comparison of these different approaches to the measurement of SO2 for the same plume is presented. Differences in these observations are used to better quantify SO2 emissions, to assess the current mismatch between ground based and remotely sensed retrievals, and to develop an approach to continuously and accurately monitor volcanic activity from space in near real-time.

  12. Volcanic emissions of metals and halogens from White Island (New Zealand) and Erebus volcano (Antarctica) determined with chemical traps

    NASA Astrophysics Data System (ADS)

    Wardell, L. J.; Kyle, P. R.; Counce, D.

    2008-11-01

    Volcanic emission rates of As, Sb, Pb, Hg, Se, Cl, and F were determined at Erebus volcano, Antarctica and White Island, New Zealand, using chemical traps. The trace metal fluxes were determined by combining the species to S ratios in the solutions with SO 2 emission rates measured by correlation spectrometry at the two volcanoes. At Erebus volcano, fluxes for the metals Pb and Hg were 2.0 × 10 - 4 and 8.1 × 10 - 6 kg s - 11 , respectively. Fluxes for Cl, F, As, Sb and Se (0.35, 0.15, 2.5 × 10 - 4 , 1.2 × 10 - 5 , and 4.5 × 10 - 6 kg s - 1 , respectively) agreed within error limits for values determined previously by the LiOH impregnated filter method [Zreda-Gostynska, G., Kyle, P., Finnegan, D., Prestbo, K., 1997. Volcanic gas emissions from Mount Erebus and their impact on the Antarctic environment. Journal of Geophysical Research, 102(B7): 15039-15055.], demonstrating the utility of the chemical trap method. A fall in the As/S ratio from 7 × 10 - 4 in 1997/1999 to 3 × 10 - 4 in 2000 at Erebus coincided with a change in the frequency and style of eruptive activity that may have been due to injection of magma into the system. At White Island, chemical trap data indicated fluxes of Cl = 0.90, F = 0.0079, Pb = 2.7 × 10 - 4 , Hg = 1.1 × 10 - 5 , As = 1.3 × 10 - 4 , Sb = 1.9 × 10 - 5 and Se = 1.5 × 10 - 5 kg s - 1 . Samples collected 600 m downwind of the active crater were comparable to samples collected adjacent to the main gas vent, showing that this method can still be used at some distance from a degassing vent.

  13. Controlled-source seismic investigations of the crustal structure beneath Erebus volcano and Ross Island, Antarctica: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Maraj, S.; Kyle, P. R.; Zandomeneghi, D.; Knox, H. A.; Aster, R. C.; Snelson, C. M.; Miller, P. E.; Kaip, G. M.

    2009-12-01

    During the 2008-09 Austral summer field season we undertook a controlled-source seismic experiment (Tomo-Erebus, TE) to examine the shallow magmatic system beneath the active Erebus volcano (TE-3D) and the crustal structure beneath Ross Island. Here we report on the TE-2D component, which was designed to produce a two-dimensional P-wave velocity model along an east-west profile across Ross Island. Marine geophysical observations near Ross Island have identified the north-south trending Terror Rift within the older and broader Victoria Land Basin, which are a component of the intraplate West Antarctic Rift System. Mount Erebus and Ross Island are circumstantially associated with the Terror Rift and its thin (~20 km) crust. The nature, extent and role of the Terror Rift in controlling the evolution of Ross Island volcanism and the on-going eruptive activity of Erebus volcano are unknown. In TE-2D, we deployed 21 seismic recorders (Ref Tek 130) with three-component 4.5 Hz geophones (Sercel L-28-3D) along a 90-km east-west line between Capes Royds and Crozier. These were supplemented by 79 similar instruments deployed for the high-resolution TE-3D experiment within a 3 x 3 km grid around the summit crater of Erebus, an array of 8 permanent short period and broadband sensors used to monitor the activity of Erebus and 23 three-component sensors (Guralp CMG-40T, 30s-100 Hz) positioned around the flanks and summit of Erebus. Fifteen chemical sources were loaded in holes drilled about 15 m deep in the snow and ice. The size of these shots ranged from 75 to 600 kg of ANFO with the largest shots at the ends of the profile. An additional shot was detonated in the sea (McMurdo Sound) using 200 kg of dynamite. Due to the rugged terrain, short field seasons and large area to be covered, the seismometer spacing along the TE-2D profile is quite large (~ 5 km spacing), resulting in poor near-surface data resolution. However, the data have a high signal to noise ratio with clear

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods Cyndi Kelly1, Jesse F. Lawrence1, Cindy Ebinger2 1Stanford University, Department of Geophysics, 397 Panama Mall, Stanford, CA 94305, USA 2University of Rochester, Department of Earth and Environmental Science, 227 Hutchison Hall, Rochester, NY 14627, USA Low-magnitude seismic signals generated by processes that characterize volcanic and hydrothermal systems and their plumbing networks are difficult to observe remotely. Seismic records from these systems tend to be extremely 'noisy', making it difficult to resolve 3D subsurface structures using traditional seismic methods. Easily identifiable high-amplitude bursts within the noise that might be suitable for use with traditional seismic methods (i.e. eruptions) tend to occur relatively infrequently compared to the length of an entire eruptive cycle. Furthermore, while these impulsive events might help constrain the dynamics of a particular eruption, they shed little insight into the mechanisms that occur throughout an entire eruption sequence. It has been shown, however, that the much more abundant low-amplitude seismic 'noise' in these records (i.e. volcanic or geyser 'tremor') actually represents a series of overlapping low-magnitude displacements that can be directly linked to magma, fluid, and volatile movement at depth. This 'noisy' data therefore likely contains valuable information about the processes occurring in the volcanic or hydrothermal system before, during and after eruption events. In this study, we present a new method to comprehensively study how the seismic source distribution of all events - including micro-events - evolves during different phases of the eruption sequence of Sierra Negra Volcano in the Galapagos Islands. We apply a back-projection search algorithm to image sources of seismic 'noise' at Sierra Negra Volcano during a proposed intrusion event. By analyzing

  15. Volcanic sulfur dioxide index and volcanic explosivity index inferred from eruptive volume of volcanoes in Jeju Island, Korea: application to volcanic hazard mitigation

    NASA Astrophysics Data System (ADS)

    Ko, Bokyun; Yun, Sung-Hyo

    2016-04-01

    Jeju Island located in the southwestern part of Korea Peninsula is a volcanic island composed of lavaflows, pyroclasts, and around 450 monogenetic volcanoes. The volcanic activity of the island commenced with phreatomagmatic eruptions under subaqueous condition ca. 1.8-2.0 Ma and lasted until ca. 1,000 year BP. For evaluating volcanic activity of the most recently erupted volcanoes with reported age, volcanic explosivity index (VEI) and volcanic sulfur dioxide index (VSI) of three volcanoes (Ilchulbong tuff cone, Songaksan tuff ring, and Biyangdo scoria cone) are inferred from their eruptive volumes. The quantity of eruptive materials such as tuff, lavaflow, scoria, and so on, is calculated using a model developed in Auckland Volcanic Field which has similar volcanic setting to the island. The eruptive volumes of them are 11,911,534 m3, 24,987,557 m3, and 9,652,025 m3, which correspond to VEI of 3, 3, and 2, respectively. According to the correlation between VEI and VSI, the average quantity of SO2 emission during an eruption with VEI of 3 is 2-8 × 103 kiloton considering that the island was formed under intraplate tectonic setting. Jeju Island was regarded as an extinct volcano, however, several studies have recently reported some volcanic eruption ages within 10,000 year BP owing to the development in age dating technique. Thus, the island is a dormant volcano potentially implying high probability to erupt again in the future. The volcanoes might have explosive eruptions (vulcanian to plinian) with the possibility that SO2 emitted by the eruption reaches stratosphere causing climate change due to backscattering incoming solar radiation, increase in cloud reflectivity, etc. Consequently, recommencement of volcanic eruption in the island is able to result in serious volcanic hazard and this study provides fundamental and important data for volcanic hazard mitigation of East Asia as well as the island. ACKNOWLEDGMENTS: This research was supported by a grant [MPSS

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  17. High-K andesite petrogenesis and crustal evolution: Evidence from mafic and ultramafic xenoliths, Egmont Volcano (Mt. Taranaki) and comparisons with Ruapehu Volcano, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Price, Richard C.; Smith, Ian E. M.; Stewart, Robert B.; Gamble, John A.; Gruender, Kerstin; Maas, Roland

    2016-07-01

    This study uses the geochemistry and petrology of xenoliths to constrain the evolutionary pathways of host magmas at two adjacent andesitic volcanoes in New Zealand's North Island. Egmont (Mt. Taranaki) is located on the west coast of the North Island and Ruapehu lies 140 km to the east at the southern end of the Taupo Volcanic Zone, the principal locus of subduction-related magmatism in New Zealand. Xenoliths are common in the eruptives of both volcanoes but the xenoliths suites are petrographically and geochemically different. Ruapehu xenoliths are predominantly pyroxene-plagioclase granulites derived from Mesozoic meta-greywacke basement and the underlying oceanic crust. The xenolith population of Egmont Volcano is more complex. It includes sedimentary, metamorphic and plutonic rocks from the underlying basement but is dominated by coarse grained, mafic and ultramafic igneous rocks. Gabbroic xenoliths (Group 1) are composed of plagioclase, clinopyroxene and amphibole whereas ultramafic xenoliths are dominated by amphibole (Group 2) or pyroxene (Group 3) or, in very rare cases, olivine (Group 4). In Group 1 xenoliths plagioclase and clinopyroxene and in some cases amphibole show cumulate textures. Amphibole also occurs as intercumulate poikilitic crystals or as blebs or laminae replacing pyroxene. Some Group 2 xenoliths have cumulate textures but near monomineralic amphibole xenoliths are coarse grained with bladed or comb textures. Pyroxene in Group 3 xenoliths has a polygonal granoblastic texture that is commonly overprinted by veining and amphibole replacement. Group 1 and most Group 2 xenoliths have major, trace element and Sr, Nd and Pb isotope compositions indicating affinity with the host volcanic rocks. Geochemical variation can be modelled by assimilation fractional crystallisation (AFC) and fractional crystallisation (FC) of basaltic parents assuming an assimilant with the composition of average crystalline basement and Group 1 xenoliths have

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Trusdell, Frank A.; Moore, Richard B.; Sako, Maurice; White, Randall A.; Koyanagi, Stuart K.; Chong, Ramon; Camacho, Juan T.

    2005-08-01

    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

  1. 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

  2. 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.

  3. 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.

  4. Volcanoes of the Alaska Peninsula and Aleutian Islands, Alaska: selected photographs

    USGS Publications Warehouse

    Neal, Christina A.; McGimsey, Robert G.

    2002-01-01

    This CD-ROM contains 97 digital images of volcanoes along the Aleutian volcanic arc in Alaska. Perspectives include distant aerial shots, ground views of volcanic products and processes, and dramatic views of eruptions in progress. Each image is stored as a .PCD file in five resolutions. Brief captions, a location map, and glossary are included.

  5. Imaging rapidly deforming ocean island volcanoes in the western Galápagos 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, Galápagos. 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 Galápagos 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.

  6. Hydroacoustic records and a numerical model of the source mechanism from the first historical eruption of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Dziak, R. P.; Park, M.; Matsumoto, H.; Byun, S.-K.

    2005-08-01

    Anatahan Volcano in the Commonwealth of the Northern Mariana Islands (CNMI) erupted for the first time in recorded history on 10 May 2003. The underwater acoustic records ( T-waves) of earthquakes, explosions, and tremor produced during the eruption were recorded on a sound channel hydrophone deployed in February 2003. Acoustic propagation models show that the seismic to acoustic conversion at Anatahan is particularly efficient, aided by the upward slope of the seamount toward the hydrophone. The hydrophone records confirm the onset of earthquake activity between 0100 and 0200Z on 10 May, with a substantial increase in seismicity beginning at ˜ 0620Z. In addition, the onset of continuous, low-frequency (3-40 Hz) acoustic energy that is likely volcanic tremor related to magma intrusion was also observed at 0620Z. The hydrophone recorded 1401 earthquakes during the first 3 days of the eruption. A histogram of seismicity indicates two main periods of explosion/eruption activity, the first beginning at ˜ 0620Z on 10 May and the second at ˜ 0000Z on 11 May. Relative earthquake depth estimates indicate that both eruption periods were accompanied by earthquake activity from deep within the Anatahan volcanic edifice. A numerical representation of the Anatahan volcano-seismic source was developed to examine the character of acoustic signals generated from the eruption governed by the geometry of the source and the physical properties of the magma. A magma pipe source mechanism is used to compute the seismo-acoustic wavefield on the flank of the Anatahan volcanic edifice (on the seafloor and in the water column) due to mode conversion by roughness scattering. A fluid-filled pipe model was chosen because it allows for a more straightforward relation between volcano geometry and spectral features of harmonic tremor as well as its morphologic similarity to a submerged volcanic edifice.

  7. 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.

  8. The 2003 phreatomagmatic eruptions of Anatahan volcano—textural and petrologic features of deposits at an emergent island volcano

    NASA Astrophysics Data System (ADS)

    Pallister, John S.; Trusdell, Frank A.; Brownfield, Isabelle K.; Siems, David F.; Budahn, James R.; Sutley, Steven F.

    2005-08-01

    Stratigraphic and field data are used in conjunction with textural and chemical evidence (including data from scanning electron microscope, electron microprobe, X-ray fluorescence, X-ray diffraction, and instrumental neutron activation analysis) to establish that the 2003 eruption of Anatahan volcano was mainly phreatomagmatic, dominated by explosive interaction of homogeneous composition low-viscosity crystal-poor andesite magma with water. The hydromagmatic mode of eruption contributed to the significant height of initial eruptive columns and to the excavation and eruption of altered rock debris from the sub-volcanic hydrothermal system. Volatile contents of glass inclusions in equilibrium phenocrysts less abundances of these constituents in matrix glass times the estimated mass of juvenile magma indicate minimum emissions of 19 kt SO 2 and 13 kt Cl. This petrologic estimate of SO 2 emission is an order-of-magnitude less than an estimate from TOMS. Similarly, inferred magma volumes from the petrologic data are an order of magnitude greater than those modeled from deformation data. Both discrepancies indicate additional sources of volatiles, likely derived from a separate fluid phase in the magma. The paucity of near-source volcanic-tectonic earthquakes preceding the eruption, and the dominance of sustained long-period tremor are attributed to the ease of ascent of the hot low-viscosity andesite, followed by a shallow phreatomagmatic mode of eruption. Phreatomagmatic eruptions are probably more common at emergent tropical island volcanoes, where shallow fresh-water lenses occur at near-sea-level vents. These relations suggest that phreatomagmatic explosions contributed to the formation of many of the near-sea-level craters and possibly even to the small calderas at the other Mariana islands.

  9. Chronology of the seismic and ground deformation precursors of the 2014 Fogo Volcano - Cape Verde Islands - eruption.

    NASA Astrophysics Data System (ADS)

    Day, S. J.; Faria, B. V. E.

    2015-12-01

    The most recent eruption of Fogo Volcano, Cape Verde Islands started on the 23 November 2014 at 10h15 (CVT), after 19 years of quiescence. Several months before the begging of the eruption, the seismic activity started to deviate from the baseline, with the appearance of a class of events that was not recorded before then. This activity was characterized by a significant number of instrumentally detected, very low magnitude seismic events, sometimes more than 100 per day. In September those events became more energetic and analysis indicated that they could be of volcano-tectonic (VT) origin. The first VT event to be located was on 4 October with a 2.5 local magnitude: it was located slightly to the south of the middle of the island at between 15.5 and 16 km depth. This was deeper than normal for background VT events and coincided with the depth of last magma equilibration in the 1995 eruption. It was therefore interpreted as a possible precursor of an eruption: thus the alert level was raised to level 2, and the civil protection authorities were informed. On the following weeks the rate of VT events slightly increased and the focal depths became shallower. Very sporadic harmonic volcano tremor episodes and very few and weak long-period events were also recorded. From about the 15 to 21 November, the VT activity rate oscillated, and hypocentres tended to gather in the vicinity of an inferred dike emplacement and at shallower depth - 6 to 5 km b.s.l. On the first hours of the 22 November seismic rate increased from 3 to 6 events per hour and the events became more energetic. After 19h30 (CVT), when the magma reached the ductile-brittle transition zone (5 to 4 km b.s.l), the seismic rate increased again to more than one event per minute; earthquake magnitudes increased as well. At about 03h00 (CVT) the tilt records shown a prominent ground deformation. Continuous volcanic tremor started only one to half an hour before the start of the eruption.

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

    PubMed

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

    2016-05-09

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

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

    PubMed Central

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

    2016-01-01

    The residual hydrothermalism associated with submarine volcanoes, following an eruption event, plays an important role in the supply of CO2 to the ocean. The emitted CO2 increases the acidity of seawater. The submarine volcano of El Hierro, in its degasification stage, provided an excellent opportunity to study the effect of volcanic CO2 on the seawater carbonate system, the global carbon flux, and local ocean acidification. A detailed survey of the volcanic edifice was carried out using seven CTD-pH-ORP tow-yo studies, localizing the redox and acidic changes, which were used to obtain surface maps of anomalies. In order to investigate the temporal variability of the system, two CTD-pH-ORP yo-yo studies were conducted that included discrete sampling for carbonate system parameters. Meridional tow-yos were used to calculate the amount of volcanic CO2 added to the water column for each surveyed section. The inputs of CO2 along multiple sections combined with measurements of oceanic currents produced an estimated volcanic CO2 flux = 6.0 105 ± 1.1 105 kg d−1 which is ~0.1% of global volcanic CO2 flux. Finally, the CO2 emitted by El Hierro increases the acidity above the volcano by ~20%. PMID:27157062

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  13. Composition, geometry, and emplacement dynamics of a large volcanic island landslide offshore Martinique: From volcano flank-collapse to seafloor sediment failure?

    NASA Astrophysics Data System (ADS)

    Brunet, Morgane; Le Friant, Anne; Boudon, Georges; Lafuerza, Sara; Talling, Peter; Hornbach, Matthew; Ishizuka, Osamu; Lebas, Elodie; Guyard, Hervé

    2016-03-01

    Landslides are common features in the vicinity of volcanic islands. In this contribution, we investigate landslides emplacement and dynamics around the volcanic island of Martinique based on the first scientific drilling of such deposits. The evolution of the active Montagne Pelée volcano on this island has been marked by three major flank-collapses that removed much of the western flank of the volcano. Subaerial collapse volumes vary from 2 to 25 km3 and debris avalanches flowed into the Grenada Basin. High-resolution seismic data (AGUADOMAR-1999, CARAVAL-2002, and GWADASEIS-2009) is combined with new drill cores that penetrate up to 430 m through the three submarine landslide deposits previously associated to the aerial flank-collapses (Site U1399, Site U1400, Site U1401, IODP Expedition 340, Joides Resolution, March-April 2012). This combined geophysical and core data provide an improved understanding of landslide processes offshore a volcanic island. The integrated analysis shows a large submarine landslide deposit, without debris avalanche deposits coming from the volcano, comprising up to 300 km3 of remobilized seafloor sediment that extends for 70 km away from the coast and covers an area of 2100 km2. Our new data suggest that the aerial debris avalanche deposit enter the sea but stop at the base of submarine flank. We propose a new model dealing with seafloor sediment failures and landslide propagation mechanisms, triggered by volcanic flank-collapse events affecting Montagne Pelée volcano. Newly recognized landslide deposits occur deeper in the stratigraphy, suggesting the recurrence of large-scale mass-wasting processes offshore the island and thus, the necessity to better assess the associated tsunami hazards in the region.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  15. 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.

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

    PubMed Central

    Searl, A; Nicholl, A; Baxter, P

    2002-01-01

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

  17. Petrologic observations and multiphase dynamics in highly-crystalline magmatic mushes sourcing Galápagos 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 Galápagos 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 Rábida Island of the Galápagos 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

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

    The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent) of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community. PMID:25047077

  20. 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.

  1. Magma storage and migration associated with the 2011-2012 El Hierro eruption: Implications for crustal magmatic systems at oceanic island volcanoes

    NASA Astrophysics Data System (ADS)

    González, Pablo J.; Samsonov, Sergey V.; Pepe, Susi; Tiampo, Kristy F.; Tizzani, Pietro; Casu, Francesco; Fernández, José; Camacho, Antonio G.; Sansosti, Eugenio

    2013-08-01

    Starting in July 2011, anomalous seismicity was observed at El Hierro Island, a young oceanic island volcano. On 12 October 2011, the process led to the beginning of a submarine NW-SE fissural eruption at ~15 km from the initial earthquake loci, indicative of significant lateral magma migration. Here we conduct a multifrequency, multisensor interferometric analysis of spaceborne radar images acquired using three different satellite systems (RADARSAT-2, ENVISAT, and COSMO-SkyMed (Constellation of Small Satellites for Mediterranean Basin Observation)). The data fully captures both the pre-eruptive and coeruptive phases. Elastic modeling of the ground deformation is employed to constrain the dynamics associated with the magmatic activity. This study represents the first geodetically constrained active magmatic plumbing system model for any of the Canary Islands volcanoes, and one of the few examples of submarine volcanic activity to date. Geodetic results reveal two spatially distinct shallow (crustal) magma reservoirs, a deeper central source (9.5 ± 4.0 km), and a shallower magma reservoir at the flank of the southern rift (4.5 ± 2.0 km). The deeper source was recharged, explaining the relatively long basaltic eruption, contributing to the observed island-wide uplift processes, and validating proposed active magma underplating. The shallowest source may be an incipient reservoir that facilitates fractional crystallization as observed at other Canary Islands. Data from this eruption supports a relationship between the depth of the shallow crustal magmatic systems and the long-term magma supply rate and oceanic lithospheric age. Such a relationship implies that a factor controlling the existence/depth of shallow (crustal) magmatic systems in oceanic island volcanoes is the lithosphere thermomechanical behavior.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    PubMed

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

    2003-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wiens, Douglas A.; Pozgay, Sara H.; Shore, Patrick J.; Sauter, Allan W.; White, Randall A.

    2005-09-01

    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 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.

  5. 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

  6. 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

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

    NASA Astrophysics Data System (ADS)

    Hernández, P. A.; Padilla, G.; Calvo, D.; Padrón, E.; Melian, G.; Dionis, S.; Nolasco, D.; Barrancos, J.; Rodríguez, F.; Pérez, 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 Montañas 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 605°C, 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

  8. Magma chamber history related to the shield building stage of Piton des Neiges volcano, La Réunion Island

    NASA Astrophysics Data System (ADS)

    Berthod, Carole; Michon, Laurent; Famin, Vincent; Bascou, Jérôme; Bachelery, Patrick

    2016-04-01

    reconstruction, gravimetric data (Gailler & Lénat, 2012) and submarine sedimentation (Lebas, 2012). It would have been built prior to 2 Ma and subsequently experienced a large north-directed destabilization. The PdN volcano later reconstructed south of the initial magmatic centre. Chevallier, L., & Vatin-Perignon, N. (1982). Volcano-structural evolution of Piton des Neiges, Reunion Island, Indian Ocean. Bulletin of Volcanology, 45(4), 285-298. Gailler, L.-S., & Lénat, J.-F. (2012). Internal architecture of La Réunion (Indian Ocean) inferred from geophysical data. Journal of Volcanology and Geothermal Research, 221-222(C), 83-98. http://doi.org/10.1016/j.jvolgeores.2012.01.015 Lebas, E. (2012). Processus de démantèlement des édifices volcaniques au cours de leur évolution : Application à La Réunion et Montserrat et comparaison avec d'autres édifices. Unpublished PhD Thesis, 1-379. Upton, B. G. J., & Wadsworth, W. (1972). Peridotitic and gabbroic rocks associated with the shield-forming lavas of Réunion. Contributions to Mineralogy and Petrology, 35, 139-158.

  9. 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.

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

    USGS Publications Warehouse

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

    2000-01-01

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

  11. 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.

  12. 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.

  13. 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 1992–2000, document coeruptive and posteruptive deformation of the 1992–1993 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.

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

    NASA Astrophysics Data System (ADS)

    Chadwick, William W.; de Roy, Tui; Carrasco, Alfredo

    1991-05-01

    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 ( m b 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 ( m b 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.

  15. Origin of high-silica liquids at Stromboli volcano (Aeolian Islands, Italy) inferred from crustal xenoliths

    NASA Astrophysics Data System (ADS)

    Renzulli, A.; Serri, G.; Santi, P.; Mattioli, M.; Holm, P. M.

    High-silica igneous xenoliths (granophyre and obsidian fragments with SiO2 ca. 75 wt.%) and high-silica glass (SiO2 between ca. 64 and 75 wt.%) within glass-bearing tonalitic and dioritic xenoliths have been discovered at Stromboli. They are well beyond the silica range of the volcanic rocks erupted during the subaerial activity of the volcano. The granophyre and the obsidian fragments occur within the Petrazza pyroclastics (high-K andesite pumiceous scoriae) of the Paleostromboli I period (� to >61 ka), whereas the glass-bearing tonalites and diorites are hosted in the Omo basaltic-andesite lava flows of the Paleostromboli II period (64-55 ka). The obsidian represents an extremely evolved liquid derived from low-pressure fractional crystallization of high-K calc-alkaline magmas of Stromboli, coupled with minor assimilation of upper crust or terrigenous sediments. The other studied high-silica products have an anatectic origin. The granophyre composition is compatible with a genesis by low-degree melting of leucotonalites similar to some Calabrian Arc lithotypes. Partial melting of crustal rocks from the Stromboli basement is also demonstrated by interstitial glass in the tonalite and diorite xenoliths. Textural evidence and the presence of variable glass compositions suggest that in these plutonic xenoliths the melt chemistry was controlled by dehydration melting of biotite and non-modal melting of local mineralogy. High-degree undercooling of granophyre melt and of the partially melted xenoliths is consistent with rapid rise of the host magmas leading to eruption. Whether partial melting was initiated during stoping and transport of xenoliths within the rising magma or in situ during magma storage within the crust has not been unequivocally established.

  16. Rapid time scales of basalt to andesite differentiation at Anatahan volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Reagan, Mark; Tepley, Frank J.; Gill, James B.; Wortel, Matthew; Hartman, Brian

    2005-08-01

    We present comprehensive U-series data ( 238U- 234U- 230Th- 226Ra- 210Pb- 210Po and ( 230Th)/( 232Th)) for an andesite from an oceanic arc. The juvenile Anatahan andesite has U-Th systematics colinear with other historical Mariana volcanic rocks, and is most similar to those of the other volcano in the Mariana arc with a significant proportion of silicic andesite: Uracas. Like Uracas, the parental basalt for the Anatahan andesite was generated by relatively low degrees of flux melting from a source previously enriched in a sediment component from the subducting slab. However, the Anatahan andesite is much more strongly enriched in 226Ra over 230Th than Uracas lavas, and has one of the highest ( 226Ra)/( 232Th) ratios of siliceous andesites globally. The long-lived disequilibria between 238U- 230Th- 226Ra in the Anatahan andesite are inherited from basalt genesis, not created during differentiation or eruption. Thus, the time between genesis of the parental basalt and eruption of andesite at Anatahan is shorter than for Uracas. Moreover, the near-equilibrium ( 210Pb)/( 226Ra) value indicates that the magma body did not persistently lose or gain 222Rn for more than 2 years before eruption. This permits differentiation of the parental basalt to form andesite within this 2-year time period, although a differentiation time period between 100 and a few thousand years also is possible. The relative activities between 210Po and 210Pb suggest erupted scoria degassed Po less than most lavas despite eruption plume heights of ˜10 km, which further suggests an unusually rapid ascent before eruption. These data also show that juvenile material was ejected from the first day of the eruption. Phreatomagmatic ejecta overlying the main Anatahan scoria is strongly enriched in 210Po over 210Pb, indicating that a significant proportion of the Po degassed from rising magmas sublimes in its shallow fumarolic conduit system.

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

    NASA Astrophysics Data System (ADS)

    Huang, F.; Lundstrom, C. C.

    2005-12-01

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

  18. Geochemical Characteristics of the Lavas from the "Adventive Cones" of Piton de La Fournaise Volcano (La Reunion Island)

    NASA Astrophysics Data System (ADS)

    Valer, M.; Bachelery, P.; Schiano, P.; Upton, B. G. J.

    2015-12-01

    Piton de la Fournaise, the youngest volcano of La Réunion Island, is renowned for being frequently active. Whereas the current activity is mainly located within the "Enclos Fouqué" caldera, ~100 strombolian cones lie on the volcano's flanks, thought to date from ~300 years to a few thousand years. Our study focuses on these "adventive cones", by studying bulk-rock major and trace element compositions, mineral phase compositions and olivine-hosted melt inclusions. The Piton de la Fournaise lavas (younger than ~450 ka) have been subdivided into three compositional groups (see attached figure, and Lénat et al. 2012). Almost all recent and historical lavas belong to two of these groups: "cotectic basalts" and "olivine-rich basalts", marked by a constant CaO/Al2O3 ratio of ~0.8, and MgO content ranging from 5 to 30 wt % reflecting different degrees of olivine accumulation. The third group, called here "mid-alkaline basalts", corresponds to compositions commonly encountered for the "adventive cones". It mainly consists of magnesian basalts at 7.55 - 10.24 wt% MgO and CaO/Al2O3 values down to 0.55. At constant MgO content, this group shows higher alkali content and a relative deficiency in Ca compared to the historic basalts. The "adventive cones" lavas usually contain magnesian olivines (Fo > 86). Such crystals are not at the equilibrium with their host lava, raising thus the question of the recycling processes. According to Bureau et al. (1998; 1999), magnesian olivines come from deep storage levels. The specific geochemistry of the "adventive cones" lavas is attributed either to a high-pressure fractionation of a clinopyroxene-rich assemblage (Albarède et al. 1997), or to an assimilation process involving wehrlite-gabbro cumulates (e.g. Salaün et al. 2010). Our new data show that the source of these magmas is chemically homogeneous to that of current magmas. However, their ascent clearly bypasses the current lava reservoirs, especially the shallow magma chamber.

  19. 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.

  20. 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

  1. Don't Forget Kīlauea: Explosive Hazards at an Ocean Island Basaltic Volcano

    NASA Astrophysics Data System (ADS)

    Swanson, D. A.; Houghton, B. F.

    2015-12-01

    Kīlauea alternates between periods of high and low magma supply rate, each period lasting centuries. The low rate is only a few percent of the high rate. High supply rate, typified by the past 200 years, leads to frequent lava flows, elevated SO2 emission, and relatively low-hazard Hawaiian-style explosive activity (lava fountains, spattering). Periods of low magma supply are very different. They accompany formation and maintenance of a deep caldera, the floor of which is at or below the water table, and are characterized by phreatomagmatic and phreatic explosive eruptions largely powered by external water. The low magma supply rate results in few lava flows and reduced SO2 output. Studies of explosive deposits from the past two periods of low magma supply (~200 BCE-1000 CE and ~1500-1800 CE) indicate that VEIs calculated from isopach maps can range up to a low 3. Clast-size studies suggest that subplinian column heights can reach >10 km (most recently in 1790), though more frequent column heights are ~5-8 km. Pyroclastic density currents (PDCs) present severe proximal hazards; a PDC in 1790 killed a few hundred people in an area of Hawaíi Volcanoes National Park today visited by 5000 people daily. Ash in columns less than about 5 km a.s.l. is confined to the trade-wind regime and advects southwest. Ash in higher columns enters the jet stream and is transported east and southeast of the summit caldera. Recurrence of such column heights today would present aviation hazards, which, for an isolated state dependent on air transport, could have especially deleterious economic impact. There is currently no way to estimate when a period of low magma supply, a deep caldera, and powerful explosive activity will return. Hazard assessments must take into account the cyclic nature of Kīlauea's eruptive activity, not just its present status; consequently, assessments for periods of high and low magma supply rates should be made in parallel to cover all eventualities.

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

    USGS Publications Warehouse

    Chadwick, W.W.; 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.

  3. Recent activity of Anatahan volcano, Northern Marina Islands, and its magma plumbing system

    NASA Astrophysics Data System (ADS)

    Nakada, S.; Morita, Y.; Matsushima, T.; Tabei, T.; Watanabe, A.; Maeno, F.; Camacho, J. T.

    2009-12-01

    The volcanic activity of Anatahan that began in 2003 has declined such as faint emission of volcanic gas from the crater and scarcity of volcanic tremor in 2009. Our team carried out geological, geodetic and seismological observation repeatedly till mid-2009 from the beginning of the eruption. The early phase of the eruption (2003-2004) can be characterized by magmatic and phreatomagmatic explosions, contrasting to mainly phreatic nature in the later phase (2005-2008). The active crater (Eastern Crater) was widened and deepened (much below the sea level) as the eruption progressed. Dominant products of phreatic explosions comprise of thick accumulation of thin layers of fine ash. A rough estimate of the total volume during these 5 years is as much as 1 km3, close to the volume of materials lost by enlargement of the active crater. Seismic observation was carried out during mid-2008 and mid-2009 by settling 5 temporary stations covering the whole of the island, each of which includes a 3 components short-period seismometer with corner frequency of 1Hz and a low-power consumption digital data recorder with 24-bits AD resolutions. GPS campaign observation was repeated in the same station during this period. VT and LP event were observed, though very low in occurrence in this period. Hypocenters of VT and LP events show all events occurred at the depth of less than 8km around the eastern crater. Among them, LP events occurred in the shallower (less than 3km) region. The error in the depth may be not more than a few kilometers, but that in the epicenter should be smaller than 1km because the most events are located inside of the seismic network. Moreover, the tremors observed in the 2008 summer continued for about 3 weeks. The amplitude increased gradually, kept at the maximum, and stopped abruptly. During the maximum amplitude period, ash emission was observed by VAAC. Estimated reduced displacement at the maximum is about 1 cm2, typical of a hydro-magmatic eruption

  4. 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

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

  8. 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

  9. 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.

  10. 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

  11. 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.

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

    PubMed Central

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

    2012-01-01

    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

  13. Education: Solomons Winner in Lengthy Plagiarism Trial.

    ERIC Educational Resources Information Center

    Stinson, Steve

    1980-01-01

    Reports the outcome of a plagiarism suit against organic chemistry professor T. W. Graham Solomons by two emeritus professors at New York University. The ruling of not guilty leaves the way open for Solomons' counterclaim that he lost sales of the book because of the suit. (Author/SA)

  14. 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

  15. A Sheared Sill Triggers Large Flank Displacements at Piton de la Fournaise Volcano (Réunion Island)

    NASA Astrophysics Data System (ADS)

    Tridon, M.; Cayol, V.; Froger, J. L.; Augier, A.

    2015-12-01

    In April 2007, an eruption with an exceptional intensity occured 7 km southeast of the central cone of the Piton de la Fournaise (Réunion Island). ALOS and ENVISAT satellites recorded up to 1.4 meter of displacement towards the east, and a general subsidence up to 45 cm of the Eastern Flank of the volcano. This movement continued for more than one year after the end of the eruption. In this work, we address the Eastern Flank displacement during and after the April 2007 eruption by inverting post-eruptive InSAR data. Our purpose is twofold: assess the hazard associated to flank displacement and understand the origin of the distal location of the eruption. C-band ENVISAT interferograms from six different lines of sight were interpolated to cover a common period from May 2007 to July 2008. We combine a Mixed Boundary Element Method (MBEM) assuming linear elasticity of the edifice and a Neighborhood Algorithm to invert the surface displacement. The real topography is taken into account using a Digital Elevation Model. The fracture geometry is supposed to be a curved quadrangle. Linear parameters such as pressure and shear stress are also inverted. Inversion results show that a 5 by 8 km trapezoïdal fracture reproduces well the first order displacement of the Eastern Flank. The fracture is 500 to 1000 m deep with a low dip angle to the East. It links the summit cone to the eruptive fissure of April 2007 which corresponds to the expected magma path. The fracture is submitted to an eastward slip up to around 25 cm, and a closure up to 20 cm. To confirm the surprising result of a closure, we made an inversion with a version of MBEM where closure is forbidden and we tested a linear inversion of slip distribution on a fracture of the same geometry assuming an elastic half space. These inversions confirmed the closure and lead us to propose that the source of the April 2007 eruption is a sheared sill, which underwent closure in the post-eruptive period.

  16. The Variability of Refractivity in the Atmospheric Boundary Layer of a Tropical Island Volcano Measured by Ground-Based Interferometric Radar

    NASA Astrophysics Data System (ADS)

    Wadge, G.; Costa, A.; Pascal, K.; Werner, C.; Webb, T.

    2016-11-01

    For 24 h we measured continuously the variability of atmospheric refractivity over a volcano on the tropical island of Montserrat using a ground-based radar interferometer. We observed variations in phase that we interpret as due to changing water vapour on the propagation path between the radar and the volcano and we present them here in the context of the behaviour of the atmospheric boundary layer over the island. The water vapour behaviour was forced by diurnal processes, the passage of a synoptic-scale system and the presence of a plume of volcanic gas. The interferometer collected images of amplitude and phase every minute. From pairs of phase images, interferograms were calculated and analyzed every minute and averaged hourly, together with contemporaneous measurements of zenith delays estimated from a network of 14 GPS receivers. The standard deviation of phase at two sites on the volcano surface spanned a range of about 1-5 radians, the lowest values occurring at night on the lower slopes and the highest values during the day on the upper slopes. This was also reflected in spatial patterns of variability. Two-dimensional profiles of radar-measured delays were modelled using an atmosphere with water vapour content decreasing upwards and water vapour variability increasing upwards. Estimates of the effect of changing water vapour flux from the volcanic plume indicate that it should contribute only a few percent to this atmospheric variability. A diurnal cycle within the lower boundary layer producing a turbulence-dominated mixed layer during the day and stable layers at night is consistent with the observed refractivity.

  17. 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

  18. 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.

  19. Regional Transport of Pollutants Emitted From The June-july 2001 Eruption of The Piton De La Fournaise Volcano (reunion Island).

    NASA Astrophysics Data System (ADS)

    Bhugwant, C.; Siéja, B.; Rivière, E.; Perron, L.; Staudacher, T.

    This study presents a survey of SO2 emitted by a notable volcanic eruption, which occurred from 11th June 2001 to 7th July 2001 at the Piton de la Fournaise volcano (Reunion island). For this purpose, atmospheric measurements were performed for the first time at 8 distinct locations over the island during austral autumn-early win- ter period (May-July 2001). Three locations (Lislet Geoffroy : site 1, Notre Dame de la Délivrance : site 2 and La Plaine des Palmistes : site 3) are situated on the lee- ward (eastern-to-northern) side and the five others (CIRFIM : site 4, EDF : site 5, Sainte-Thérèse : site 6, Cambaie : site 7 and Saint-Louis: site 8) are situated on the windward (north-western to south-western) side of the island. Hourly SO2 concentra- tion measured over La Reunion island vary in the 1-40 microg/m3 range in normal conditions, following the location, while it indicated notable increase (enhancement factor: ~5 to 20, following the site) during the whole volcanic eruption period. En- hancement factors of up to 10-60 (following the location) maintained for several hours were importantly noticed on the SO2 concentration variability at the 8 measurement sites, during intense volcanic degassing episodes at the Piton de la Fournaise volcano. The SO2 peaks observed over different parts of the island were strongly corroborated with eruption tremor permanently measured by the Piton de la Fournaise seismic net- work, which indicated the intensity variation of the volcanic eruption episodes during June-July 2001. Winds analysis point out that the SO2 emitted during the volcanic eruption were subject to local-to-regional transport over La Reunion island due to its particular geographic configuration (important relief) and to prevailing meteorologi- cal conditions (anticyclone). They also indicated that the volcanic eruption pollutants were transported over the south-western Indian Ocean via convective/dynamical pro- cesses, and might regionally impact the

  20. 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

  1. 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. Antão is characterized by frequent seismic swarms composed of VT earthquakes (0.1

  2. Characteristics on fault coupling along the Solomon megathrust based on GPS observations from 2011 to 2014

    NASA Astrophysics Data System (ADS)

    Kuo, Yu-Ting; Ku, Chin-Shang; Chen, Yue-Gau; Wang, Yu; Lin, Yu-Nung Nina; Chuang, Ray Y.; Hsu, Ya-Ju; Taylor, Frederick W.; Huang, Bor-Shouh; Tung, Hsin

    2016-08-01

    The Solomon megathrust along the western Solomon arc generated two megathrust earthquakes in the past decade (Mw 8.1 in 2007 and Mw 7.1 in 2010). To investigate the interseismic deformation and inferred coupling on the megathrust, we deployed the first continuous GPS network in the Western Solomon Islands. Our 2011-2014 GPS data and the back slip inversion model show coupling ratio as high as 73% along the southeastern 2007 rupture segment but only 10% on average along the segment of 2010 event. Based on the spatial distribution of coseismic slip, aftershock clusters, derived coupling pattern, and paleogeodetic records, we discovered the former as a semipermanent asperity and the latter as a potential megathrust barrier. We propose that a characteristic earthquake of magnitude not less than Mw 8 will recur in an interval of 100 or more years by either single or doublet earthquake.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    have co-located a broadband seismometer (100 Hz sample rate). Of particular interest in this analysis is the separation of any microgravity changes from the hydrothermal tremor signature. Future modelling of the Inferno Crater lake will incorporate gravity, lake level and temperature changes into a multi-phase spatio-temporal model of the subsurface. We anticipate that separation of the gravity and seismic signals may allow future constraint of the sub-surface hydrothermal processes which control cyclic behaviour. We also will show results of a planned deployment of the new gravity meter to White Island volcano, New Zealand which will occur in March 2010. Lessons learned from the Waimangu deployment will be incorporated to understand the long-term variations of White Islands' hydrothermal and magmatic system.

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

    USGS Publications Warehouse

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

    2002-01-01

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

  5. Coeval giant landslides in the Canary Islands: Implications for global, regional and local triggers of giant flank collapses on oceanic volcanoes

    NASA Astrophysics Data System (ADS)

    Boulesteix, Thomas; Hildenbrand, Anthony; Soler, Vicente; Quidelleur, Xavier; Gillot, Pierre-Yves

    2013-05-01

    Giant landslides are an important part of the evolution of most intra-plate volcanic islands. They often proceed in catastrophic events, likely to generate voluminous debris avalanches and eventually trigger destructive tsunamis. Although knowledge of the timing of their recurrence is a key factor regarding the hazard assessment in coastal environments, only a few of them have been well dated. In this contribution, we focus on the La Orotava event on Tenerife, which we date with the unspiked K-Ar technique, between 534 and 523 ka. Such narrow temporal interval is compatible, within uncertainties, with the age of the Cumbre Nueva collapse on the neighboring island of La Palma. We thus examine here the possible common triggering mechanisms at the global, regional and local scales. Both events occurred shortly after the climax of the oxygen isotopic stage 14, during the rapid transition towards the interglacial stage 13, reinforcing the hypothesis of a control from global paleoclimatic changes on the destabilization of oceanic islands. Intense volcanic pulses at the regional scale also lead to the synchronous overgrowth of several volcanic islands in the archipelago, but coeval destabilization on Tenerife and La Palma appears significantly controlled by the intrinsic morphology of the edifices, with contrasted instability thresholds for shield volcanoes and volcanic ridges respectively. Finally, we propose that the two events may be genetically linked. Dynamic transfer of voluminous debris avalanches during a giant landslide episode can induce isostatic readjustments, generate significant ground acceleration and finally produce a large tsunami, three processes which can concur to trigger large scale flank collapse on a neighboring mature unstable volcanic island.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  7. Deformation and gravity changes at Izu islands, Japan, prior to, during, and after the 2000 caldera collapse at Miyake-jima volcano

    NASA Astrophysics Data System (ADS)

    Furuya, M.; Okubo, S.; Kimata, F.

    2006-12-01

    Eruptive and caldera-forming activity at Miyakejima volcano, Japan, was accompanied by more than 40 days of seismic swarms, including more than five M6 (or greater) earthquakes, and significant crustal deformation in nearby islands. Here we review ground deformation and gravity changes at Miyakejima and other nearby islands prior to, during, and after the 2000 caldera collapse episode at Miyakejima. While ground displacements observed at Izu-islands can be basically predicted from the Philippine Sea Plate motion in a global perspective, Miyakejima was undergoing inflation if examined locally within the island before the 2000 unrest. It is also known that a couple of leveling benchmarks inside the previous caldera were secularly subsiding [Miyazaki, 1990]. Using JERS1's InSAR data, Furuya~[2004] also confirmed this. Was the localized subsidence before 2000 a precursor for the caldera collapse? We will argue that this is probably not the case. After the beginning of the earthquake swarm on 26 June 2000, significant ground displacements were recorded at Miyakejima both in the permanent GPS stations [e.g., Nishimura et al. 2001] and tiltmeters by the NIED [Ukawa et al. 2001]. Using both FG5 absolute gravimeter and LaCoste-Romberg G-type gravimeters, high precision gravity survey has been repeatedly carried out by ERI, University of Tokyo. Furuya et al~[2003a] showed spatial-temporal gravity changes from the beginning stage to early 2001. Notably, they detected a gravity decrease of as much as 145 μgals (1 μgal=10^{-8} m/s2) at the summit area 2 days prior to the collapse, and interpreted as reflecting the formation of a large void beneath the volcano. Correcting for the effect of topography change due to the collapse, subsequent gravity change data suggested an effective density decrease until the middle August 2000, followed by a significant density increase toward at least November 2000. Those spatial and temporal gravity changes were associated with the explosive

  8. 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

  9. 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

  10. 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.

  11. Preliminary volcano-hazard assessment for Great Sitkin Volcano, Alaska

    USGS Publications Warehouse

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

    2003-01-01

    Great Sitkin Volcano is a composite andesitic stratovolcano on Great Sitkin Island (51°05’ N latitude, 176°25’ W longitude), a small (14 x 16 km), circular volcanic island in the western Aleutian Islands of Alaska. Great Sitkin Island is located about 35 kilometers northeast of the community of Adak on Adak Island and 130 kilometers west of the community of Atka on Atka Island. Great Sitkin Volcano is an active volcano and has erupted at least eight times in the past 250 years (Miller and others, 1998). The most recent eruption in 1974 caused minor ash fall on the flanks of the volcano and resulted in the emplacement of a lava dome in the summit crater. The summit of the composite cone of Great Sitkin Volcano is 1,740 meters above sea level. The active crater is somewhat lower than the summit, and the highest point along its rim is about 1,460 meters above sea level. The crater is about 1,000 meters in diameter and is almost entirely filled by a lava dome emplaced in 1974. An area of active fumaroles, hot springs, and bubbling hot mud is present on the south flank of the volcano at the head of Big Fox Creek (see the map), and smaller ephemeral fumaroles and steam vents are present in the crater and around the crater rim. The flanking slopes of the volcano are gradual to steep and consist of variously weathered and vegetated blocky lava flows that formed during Pleistocene and Holocene eruptions. The modern edifice occupies a caldera structure that truncates an older sequence of lava flows and minor pyroclastic rocks on the east side of the volcano. The eastern sector of the volcano includes the remains of an ancestral volcano that was partially destroyed by a northwest-directed flank collapse. In winter, Great Sitkin Volcano is typically completely snow covered. Should explosive pyroclastic eruptions occur at this time, the snow would be a source of water for volcanic mudflows or lahars. In summer, much of the snowpack melts, leaving only a patchy

  12. 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.

  13. 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.

  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. New K-Ar ages for calculating end-of-shield extrusion rates at West Maui volcano, Hawaiian island chain

    USGS Publications Warehouse

    Sherrod, D.R.; Murai, T.; Tagami, Takahiro

    2007-01-01

    Thirty-seven new K-Ar ages from West Maui volcano, Hawai'i, are used to define the waning stages of shield growth and a brief episode of postshield volcanism. All but two samples from shield-stage strata have reversed polarity magnetization, so conceivably the exposed shield is not much older than the Olduvai Normal-Polarity subchron, or about 1.8 Ma. The oldest ages obtained are in the range 1.9-2.1 Ma but have large analytical error. Shield volcanism ended about 1.35 Ma, and postshield volcanism followed soon thereafter, persisting until about 1.2 Ma. Exposed shield-stage strata were emplaced at a rate of about 0.001 km3 per year, a rate smaller than historic Hawaiian magmatic rates by a factor of 100. Stratigraphic accumulation rates are similar to those measured previously at Wai'anae volcano (O'ahu) or the upper part of the Mauna Kea shield sequence (Hilo drill core, Hawai'i). These rates diminish sharply during the final 0.3-0.5 m.y. of the shield stage. Hawaiian shield volcanoes begin waning well before their last 0.5 m.y. of life, then end quickly, geologically speaking, if West Maui is representative. ?? Springer-Verlag 2006.

  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

  17. Preliminary Results on the 2015 Eruption of Wolf Volcano, Isabela Island, Galápagos: Chronology, Dispersion of the Volcanic Products, and Insight into the Eruptive Dynamics

    NASA Astrophysics Data System (ADS)

    Wright, H. M. N.; Bernard, B.; Ramon, P.; Guevara, A.; Hidalgo, S.; Pacheco, D. A.; Narváez, D.; Vásconez, F.

    2015-12-01

    After 33 years of quiescence, Wolf volcano, located in the northernmost tip of Isabela Island (Galápagos Islands, Ecuador), started a new eruption on May 25, 2015. The first signs of activity were recorded at 5:50 UTC (23:50 on May 24, Local Time in Galápagos) by a seismic station installed on Fernandina island. The first visual observation was reported at 7:38 UTC (1:38 LT). Based on amateur film footage, the vent was a >800 m-long circumferential fissure that produced a >100 m-high lava curtain. The eruption also released a 15 km-high gas plume with a large amount of SO2 and minimal ash content. Lightning was observed in the plume but not near the vent. Due to complex wind directions at high altitude, the gas cloud drifted in all directions eventually coming toward the continent and producing an extremely small ashfall in Quito that was detected only through the use of homemade ashmeters. The ash sample included lava droplets, scoria, and one small fragment of reticulite, indicating high lava fountaining during the first days of the eruption. The active vents on the circumferential fissure, initially located on the SE side of the caldera outer rim, moved progressively northward, eventually extending for a total of 2 km. One week later on June 02, satellite imagery (OMI, GOME, MODIS) documented decreased volcanic activity, leaving two new lava fields covering over 17 km2 on the SE (10 km-long and up to 2 km-wide) and E (7 km-long and up to 1 km-wide, reaching the sea) flanks of the volcano. Volcanic activity resumed on June 11, and on June 13 it shifted into the caldera, apparently emerging from a fissure close to the vent from the 1982 eruption, about 4 km W of the circumferential fissure. This new lava flow covered approximately 3.5 km2 of the caldera floor. Finally, volcanic activity waned at the end of June and appeared to have ended by July 11, accounting for one of the largest eruptions in the Galápagos since 1968 based on remote sensing.

  18. New Insights into the Influence of Structural Controls Affecting Groundwater Flow and Storage Within an Ocean Island Volcano, Mauna Kea, Hawaii

    NASA Astrophysics Data System (ADS)

    Thomas, D. M.; Haskins, E.; Wallin, E.; Pierce, H. A.

    2015-12-01

    The Humu'ula Groundwater Research Project was undertaken on the Island of Hawaii in an effort to characterize the hydrologic structures controlling groundwater movement and storage within Saddle region between Mauna Loa and Mauna Kea volcanoes. In 2013, the project drilled a 1764 m, continuously-cored, borehole from an elevation of 1946 m amsl near the center of the Saddle, and has now completed a second borehole at an elevation of 1645 m on the western edge of the Saddle. Although the stratigraphy of the rocks is similar, dominantly pahoehoe lava flows with somewhat fewer a'a lavas and occasional dike rock intervals, the hydrologic character of the formation in the latter is distinctly different from the former. Whereas the former test hole encountered a few high elevation perched aquifers that were underlain by an inferred regional, dike-impounded, water table at an elevation of 1390 m amsl, the latter bore encountered a sequence of confined aquifers with heads substantially higher than depth of entry. The shallowest of the confined aquifers was encountered at an elevation of 1340 m and showed a hydrostatic head of >160 m when the capping formation was breached. Deeper confined aquifers showed initial heads of > 400 m although none had heads sufficient to discharge at the surface. Most of the confined aquifers were associated with clay-rich ash beds that mantled the more permeable lavas however one of the deeper confined zones, that showed the highest head, was associated with a highly compacted breccia zone that has tentatively been ascribed to an explosive deposit. Chemical analysis of the clasts within this layer is underway to determine whether this deposit is associated with explosive activity of Mauna Kea or with another volcano on the island. Previous geophysical surveys have suggested that these confined aquifers may extend well down the leeward slopes of Mauna Kea. Evidence of multiple confining layers within the flanks of Mauna Kea suggest that its

  19. Versatile Reed-Solomon decoders

    NASA Astrophysics Data System (ADS)

    Rajableh-Shayan, Yousef

    1990-08-01

    Reed-Solomon (RS) codes have found many applications such as space and mobile communication due to their error correcting capability (ECC) and optimum structure. It is shown that time domain algorithms are the best candidates for designing versatile hardware decoders, but syndrome based algorithms are advantageous for software decoders. The algorithms for decoding RS codes require algebraic operations over Galois fields. Parallel in, parallel out multipliers and inverters in Galois fields are considered and least complex structures for the multiplier are introduced. A new normal basis multiplier is presented, as well as a universal multiplier for multiplying two elements of Galois field 2 to the m (m=4,5,6,7,8). The time domain algorithm based on transform decoder is restructured and two versatile decoder structures are presented. Both are simple and modular, thus suitable for very large scale integration design, and can be used for decoding any primitive RS code defined in a specific Galois field. The ECC of these decoders is configurable. The structure of a universal RS decoder is also presented. The time domain decoding algorithm based on algebraic decoder is modified to reduce the complexity of the universal decoder. The ECC and the size for the Galois field of this decoder are configurable. A method is also introduced for decoding RS codes generated by any generator polynomial.

  20. Co-variation in Magma Compositions, Effusion rates and Seismic Tremor During the 2014-15 Eruption of Fogo volcano, Cape Verde Islands

    NASA Astrophysics Data System (ADS)

    Day, S. J.

    2015-12-01

    Magma compositions vary widely within many eruptions of ocean island volcanoes, particularly those in the Canaries and Cape Verde Islands. The 23 November 2014 to 7 February 2015 eruption of Fogo in the Cape Verde Islands was the first eruption in either the Canaries or the Cape Verdes to be monitored by multiple satellite instruments that measured infrared emissions of the eruption and so enabled continuous quantitative estimation of magma effusion rates and their variation through time. It is also the first eruption in the Cape Verdes for which seismic tremor intensity, indicative of magma ascent dynamics, was continuously recorded. Effusion rates were highest, peaking at about 20 m3/s, in the first five days of eruption but later asymptotic decay in effusion rate was interrupted around 9 and 16 December by pulses of increased effusion. Activity was mainly mildly explosive from December 31, accompanied by intensified seismic tremor. A final pulse of low-rate lava effusion occurred from 17 to 22 January. These data provide a new framework within which to relate compositional variations in the eruption to variations in magma ascent and effusion. We collected a suite of samples whose dates of emplacement have been determined from the date of incandescence of each sample site in high-resolution thermal infrared emissivity maps collected by satellite during the eruption. The samples are highly porphyritic and strongly alkaline in composition, as is typical of Fogo magmas. The first- (November 23/24) and last- (January) erupted magma batches show evidence for hybridization with more evolved magma batches, and the 9 and 16 December magma pulses may be distinct from the magma erupted during the main phase of the eruption. We present data on the samples that allow us to examine the hypothesis that the effusion rate variations were controlled by tapping of different parts of the magma reservoir or reservoirs during the eruption.

  1. Mount St. Helens and Kilauea volcanoes

    SciTech Connect

    Barrat, J. )

    1989-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  3. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    Fluids circulating in volcanic edifices are attracting increasing interest from scientists, mostly because their role in triggering flank instability, phreatic explosions, and eruptions has been documented in several cases worldwide [Newhall et al. 2001, Thomas et al. 2004]. Fluid pore pressure can change as an effect of either external (meteoric recharge, variation of the stress field), or endogenous causes (e.g. internal pressurization of magmatic volatiles and hydrothermal systems). The reciprocal roles of tectonics and magmatic/hydrothermal activity are still under investigation [Gottsman et al. 2007, Roeloffs et al. 2003]. We discuss the results of decennial data records collected in the aquifers of Mt Etna, Vulcano Island and Mt Vesuvius, and get insights on the role of tectonics and volcanic activity on the observed variations of water level and chemical composition. In Vulcano Island, the shallow thermal aquifer is deeply concerned by deep volcanic fluids. The most significant variations were observed during the 1988-96 crisis, due to the large input of steam and acidic gases from depth. In addition, the record of the water table elevation provided remarkable insights on the pressure of the volcano-hydrothermal system, which can be envisaged as the cause for the onset of the phase of higher vapor output in the fumarolic field in late 2004. On Mt. Vesuvius, the geochemical behavior of the aquifer appears strictly controlled by the input of volcanic gases and variations in the stress field. These latter, which were responsible for the seismic crisis of 1999, and the almost simultaneous increased input of CO2-rich vapor, significantly affected water chemistry and temperature, until 2006. The recent observations of low salinity, temperature, and dissolved carbon contents in groundwater provide strong evidence for reduced pressure in the volcano-hydrothermal system. The record of water chemistry available on Mt. Etna since 1994 shows coeval changes in almost all

  5. Time variability of low-temperature fumaroles at Stromboli island (Italy) and its application to volcano monitoring

    NASA Astrophysics Data System (ADS)

    Madonia, Paolo; Fiordilino, Emilio

    2013-12-01

    The constant and mild activity of Stromboli volcano (Italy) is occasionally interrupted by effusive events and/or more energetic explosions, referred to as major explosions and paroxysms, which are potentially dangerous for the human community. Although several premonitory signals for effusive phases have been identified, precursors of major explosions and paroxysms still remain poorly understood. With the aim of contributing to the identification of possible precursors of energetic events, this work discusses soil temperature data acquired in low-temperature fumaroles at Stromboli in the period 2006-2010. Data analysis revealed that short-term anomalies recorded in the thermal signal are potentially useful in predicting state changes of the volcano. In particular, sudden changes in fumarole temperatures and their hourly gradients were observed from several days to a few hours prior to fracturing and paroxysmal events, heralded by peculiar waveforms of the recorded signals. The qualitative interpretation is supported by a quantitative, theoretical treatment that uses circuit theory to explain the time dependence of the short-period temperature variations, showing a good agreement between theoretical and observational data.

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

    NASA Astrophysics Data System (ADS)

    Bagnardi, Marco; Amelung, Falk

    2012-10-01

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

  7. Burst error correction extensions for large Reed Solomon codes

    NASA Technical Reports Server (NTRS)

    Owsley, P.

    1990-01-01

    Reed Solomon codes are powerful error correcting codes that include some of the best random and burst correcting codes currently known. It is well known that an (n,k) Reed Solomon code can correct up to (n - k)/2 errors. Many applications utilizing Reed Solomon codes require corrections of errors consisting primarily of bursts. In this paper, it is shown that the burst correcting ability of Reed Solomon codes can be increased beyond (n - k)/2 with an acceptable probability of miscorrect.

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

    USGS Publications Warehouse

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wong, L. J.

    2002-12-01

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

  10. Case of correlation between Rn anomalies and seismic activity on a volcano (Vulcano Island, Southern Tyrrhenian Sea)

    SciTech Connect

    Del Pezzo, E.; Gasparini, P.; Mantovani, M.S.M.; Martini, M.; Capaldi, G.; Gomes, Y.T.; Pece, R.

    1981-09-01

    A factor of 10 increase in the Rn concentration in a shallow aquifer forefunning a shallow seismic swarm was observed at the island of Vulcano (Aeolian island arc). The peak of Rn anomaly preceded by about one month the seismic swarm, which had a cumulative magnitude of 2.1. The time lag between the two phenomena is much longer than expected, given the small energy released by the swarm. The observed phenomena may not have a direct cause-effect relationship, but they both can be a consequence of volcanic phenomena.

  11. 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

  12. 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.

  13. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

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

  14. 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."

  15. Structural Relationship Between Piton des Neiges and Piton de la Fournaise Volcanoes: New K-Ar Data and Geomorphological Study of the Takamaka Region (East Reunion Island, Indian Ocean)

    NASA Astrophysics Data System (ADS)

    Salvany, T.; Lahitte, P.; Gillot, P.; Kluska, J.

    2007-12-01

    Reunion Island (Indian ocean) is a volcanic complex resulting from hotspot activity composed of three coalescent eruptive systems. The first subaerial volcano (la Montagne massif), which only outcrops in the NW part has been dated between 2.2 and 1.8 Ma (McDougall, 1971). After a major flank collapse of this volcano (Gillot et al., 1994), Piton des Neiges (PNv) edificated from 1.2 Ma to 30 ka (McDougall., 1971; Gillot et al.,1982). then, Piton de la Fournaise volcano (PFv), one of the most active on Earth, started its activity about 530 kyr ago (Gillot et al., 1989; 1990) and was affected by 3 eastward flank collapses (Gillot et al., 1994). Its present complex morphology is characterized by large scale erosional depressions, (Cirques) cut in the volcanic structures, such as Cilaos, Mafate or Salazie in PNv, Grand Bassin between the two volcanoes, and Grand Pays in PFv. Due to the tropical conditions, deeply incised valleys are present throughout the island. The eastern part of the island (Takamaka area), where we show that products of both PNv and PFv overlap, is one of the most rainy place in the world. It is deeply incised and has been highly eroded during the coeval building stages of PFv and PNv since at least 530 kyr. In order to constrain the relationship between the PNv and PFv volcanoes and to characterise the morphological evolution of this area, we realized a new geochronological study of the different massifs based on the accurate K- Ar technique devoted to the dating of very young rocks (Cassignol technique; Gillot et Cornette, 1986). A preserved structure between the two volcano, Morne de l'Etang, is dated between 1.36 +/- 0.02 Ma, which is older than the primary known activity of Piton des Neiges (about 1.2 Ma; McDougall, 1971), to 0.97 +/- 0.02 Ma. It may either correspond to a remnant and older part of PNv or it belongs to the Proto Fournaise 'les Alizés' volcano', which existence is still debated. Our analysis also emphasizes the fact that PFv

  16. Joint analysis of electric and gravimetric data for volcano monitoring. Application to data acquired at Vulcano Island (southern Italy) from 1993 to 1996

    NASA Astrophysics Data System (ADS)

    Di Maio, Rosa; Berrino, Giovanna

    2016-11-01

    Understanding the dynamics of volcanic-hydrothermal systems is a key factor for discriminating between magmatic and hydrothermal nature of the sources responsible for the unrest phenomena observed in active volcanic areas. Numerous studies of geophysical data monitoring in volcano-geothermal districts has indeed proven that close relationships exist between the volcanic and hydrothermal fluid circulation and the anomalous geophysical signals observed at the ground surface. In this paper, a simultaneous analysis that integrates resistivity and gravity data is suggested as a useful tool to infer a consistent conceptual model of hydrothermal volcanic systems and their evolution. An application of the proposed analysis to repeated resistivity and gravity measurements performed on Vulcano Island (Aeolian Archipelago, Sicily, southern Italy) is presented with the aim of gaining information on the dynamics of the volcanic-hydrothermal system. The examined period ranges from December 1993 to September 1996, when significant changes in chemical properties, temperatures and emission rates of La Fossa crater fumaroles were observed, all indicating an increase in the flux of hot deep magmatic gases. The results of our analysis, which refers to a profile located at the foot of the northwest flank of La Fossa cone, suggest that underground cyclic water-to-vapour transformations govern the shallow hydrothermal system dynamics, generally described by a negative correlation between the monitored resistivity and gravity data. The occurrence of positive correlations between the two analysed parameters could be ascribed to volcanic dynamics, which would mask the normal hydrological and hydrothermal system behaviour.

  17. Great Balls of Fire: A probabilistic approach to quantify the hazard related to ballistics - A case study at La Fossa volcano, Vulcano Island, Italy

    NASA Astrophysics Data System (ADS)

    Biass, Sébastien; Falcone, Jean-Luc; Bonadonna, Costanza; Di Traglia, Federico; Pistolesi, Marco; Rosi, Mauro; Lestuzzi, Pierino

    2016-10-01

    We present a probabilistic approach to quantify the hazard posed by volcanic ballistic projectiles (VBP) and their potential impact on the built environment. A model named Great Balls of Fire (GBF) is introduced to describe ballistic trajectories of VBPs accounting for a variable drag coefficient and topography. It relies on input parameters easily identifiable in the field and is designed to model large numbers of VBPs stochastically. Associated functions come with the GBF code to post-process model outputs into a comprehensive probabilistic hazard assessment for VBP impacts. Outcomes include probability maps to exceed given thresholds of kinetic energies at impact, hazard curves and probabilistic isoenergy maps. Probabilities are calculated either on equally-sized pixels or zones of interest. The approach is calibrated, validated and applied to La Fossa volcano, Vulcano Island (Italy). We constructed a generic eruption scenario based on stratigraphic studies and numerical inversions of the 1888-1890 long-lasting Vulcanian cycle of La Fossa. Results suggest a ~ 10- 2% probability of occurrence of VBP impacts with kinetic energies ≤ 104 J at the touristic locality of Porto. In parallel, the vulnerability to roof perforation was estimated by combining field observations and published literature, allowing for a first estimate of the potential impact of VBPs during future Vulcanian eruptions. Results indicate a high physical vulnerability to the VBP hazard, and, consequently, half of the building stock having a ≥ 2.5 × 10- 3% probability of roof perforation.

  18. 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.

  19. Design Primer for Reed-Solomon Encoders

    NASA Technical Reports Server (NTRS)

    Perlman, M.; Lee, J. J.

    1985-01-01

    Design and operation of Reed-Solomon (RS) encoders discussed in document prepared as instruction manual for computer designers and others in dataprocessing field. Conventional and Berlekamp architectures compared. Engineers who equip computer memory chips with burst-error and dropout detection and correction find report especially useful.

  20. 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 ...

  1. Vertical Motions of Oceanic Volcanoes

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Melet, Angélique; 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.

  3. 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.

  4. 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.

  5. 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.

  6. Geochemical characteristics of the "Mid-Alkaline Basalts" from the "adventive cones" of Piton de la Fournaise volcano (La Réunion Island)

    NASA Astrophysics Data System (ADS)

    Valer, Marina; Bachèlery, Patrick; Schiano, Pierre; Upton, Brian G. J.

    2016-04-01

    Piton de la Fournaise, the youngest volcano of La Réunion Island, is renowned for being frequently active. Its lavas (younger than ~450 ka) have been subdivided into three compositional groups (see Lénat et al. 2012 for a review). Almost all recent and historical lavas belong to two of these groups: "cotectic basalts" and "olivine-rich basalts", marked by a constant CaO/Al2O3 ratio of ~0.8, and MgO content ranging from 5 to 30 wt % reflecting different degrees of olivine accumulation. Whereas that current activity is mainly located within the "Enclos Fouqué" caldera, ~100 strombolian cones lie on the volcano's flanks, thought to date from ~300 years to a few thousand years. Our study focuses on these "adventive cones", by studying bulk-rock major and trace element compositions, isotopic compositions, mineral phases and olivine-hosted melt inclusions. The bulk-rock compositions correspond to the third group of the Piton de la Fournaise lavas (see above), called the "mid-alkaline basalts". They mainly consist of magnesian basalts at 7.55 - 10.24 wt% MgO and CaO/Al2O3 values down to 0.55. At constant MgO content, this group shows higher alkali content and a relative deficiency in Ca compared to the historic basalts. The "adventive cones" lavas usually contain magnesian olivine crystals (Fo > 86). Such crystals are not at the equilibrium with their host lava, raising thus the question of the recycling processes. The volatile contents of these olivine-hosted melt inclusions (work in progress) will allow to determine if such magnesian olivine crystals come from deep storage levels, as previously proposed by Bureau et al. (1998; 1999). The specific geochemistry the "adventive cones" lavas is attributed either to a high-pressure fractionation of a clinopyroxene-rich assemblage (Albarède et al. 1997), or to an assimilation process involving wehrlite-gabbro cumulates (e.g. Salaün et al. 2010). Although the trace element data show that the source of these magmas is

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

    PubMed Central

    Villacorta, Carlos; Jaume, Damià; Oromí, 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

  8. Sulfur isotope fractionation during the May 2003 eruption of Anatahan volcano, Mariana Islands: Implications for sulfur sources and plume processes

    NASA Astrophysics Data System (ADS)

    de Moor, J. Maarten; Fischer, Tobias P.; Sharp, Zachary D.; Hauri, Erik H.; Hilton, David R.; Atudorei, Viorel

    2010-09-01

    Sulfur isotope compositions of pumice and adsorbed volatiles on ash from the first historical eruption of Anatahan volcano (Mariana arc) are presented in order to constrain the sources of sulfur erupted during the period 10-21 May, 2003. The isotopic composition of S extracted from erupted pumice has a narrow range, from δ 34S V-CDT +2.6‰ to +3.2‰, while the composition of sulfur adsorbed onto ash has a larger range (+2.8‰ to +5.3‰). Fractionation modeling for closed and open system scenarios suggests that degassing of SO 2 raised the δ 34S V-CDT value of S dissolved in the melt from an initial composition of between +1.6‰ and +2.6‰ for closed-system degassing, or between -0.5‰ and +1.5‰ for open-system degassing, however closed-system degassing is the preferred model. The calculated values for the initial composition of the magma represent a MORB-like (δ 34S V-CDT ˜ 0‰) mantle source with limited contamination by subducted seawater sulfate (δ 34S V-CDT +21‰). Modeling also suggests that the δ 34S V-CDT value of SO 2 gas in closed-system equilibrium with the degassed magma was between +0.9‰ and +2.5‰. The δ 34S V-CDT value of sulfate adsorbed onto ash in the eruption plume (+2.8‰ to +5.1‰) is consistent with sulfate formation by oxidation of magmatic SO 2 in the eruption column. The sulfur isotope composition of sulfate adsorbed to ash changes from lower δ 34S values for ash erupted early in the eruption to higher δ 34S values for ash erupted later in the eruption. We interpret the temporal/stratigraphic change in sulfate isotopic composition to primarily reflect a change in the isotopic composition of magmatic SO 2 released from the progressively degassing magma and is attributed to the expulsion of an accumulated gas phase at the beginning of the eruption. More efficient oxidation of magmatic SO 2 gas to sulfate in the early water-rich eruption plume probably contributed to the change in S isotope compositions observed in the

  9. Shallow system rejuvenation and magma discharge trends at Piton de la Fournaise volcano (La Réunion Island)

    NASA Astrophysics Data System (ADS)

    Coppola, D.; Di Muro, A.; Peltier, A.; Villeneuve, N.; Ferrazzini, V.; Favalli, M.; Bachèlery, P.; Gurioli, L.; Harris, A. J. L.; Moune, S.; Vlastélic, I.; Galle, B.; Arellano, S.; Aiuppa, A.

    2017-04-01

    deepest, least differentiated magma triggers pulses in lava and gas flux, accompanied by rapid contraction of the volcano edifice, that empties the main shallow reservoir and terminates the cycle. Such an unloading process may characterize the evolution of shallow magmatic systems at other persistently active effusive centers.

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

    PubMed

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

    2014-03-01

    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 dichlorodiphenyltrichloro-ethane (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.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Trota, A.; Houlié, 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 São 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 São Miguel and its internal deformation. The comparison of the 2000 and 2002 coordinates indicates that São Miguel accommodates moderate WNW-ESE extension at a rate slower than 5 mm yr-1.

  13. 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 Haleakalā 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 0.05–0.15 km3/kyr, only about half the long-term rate required to produce the postshield strata emplaced in the past ∼1 Myr. Haleakalā's eruptive frequency is similar to that of Hualālai volcano on the Island of Hawai‘i, 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 Hualālai.

  14. 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

  15. Species-distance relation for birds of the Solomon Archipelago, and the paradox of the great speciators

    PubMed Central

    Diamond, Jared M.; Gilpin, Michael E.; Mayr, Ernst

    1976-01-01

    For scattered remote islands and for likely forms of immigration and extinction curves, the equilibrium theory of island biogeography leads to the prediction [unk]2 log S/[unk]A[unk]D > 0, where S is the number of species on an island, A island area, and D island distance from the colonization source. This prediction is confirmed for birds of the Solomon Archipelago. Bird species can be classified into three types according to how distance affects their distributions: non-water-crossers, which are stopped completely (usually for psychological reasons) by water gaps of even 1 mile; short-distance colonists, successful at colonizing close but not remote islands; and long-distance colonists, successful at colonizing remote as well as close islands. Almost all of the “great speciators”, the species for whose inter-island geographic variation the Solomons are famous, prove to be short-distance colonists. Lack's interpretation of the decrease in S with D is shown to rest on incorrect assumptions. PMID:16592328

  16. Hawaii's volcanoes revealed

    USGS Publications Warehouse

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

    2003-01-01

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

  17. 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

  18. 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)

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

    NASA Astrophysics Data System (ADS)

    Djath, Bughsin; Babonneix, Antoine; Gourdeau, Lionel; Marin, Frédéric; 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

  20. 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.

  1. 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

  2. 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,…

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Volcano Infrasound

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  9. Regional Solutions for Regional Problems: East Timor and Solomon Islands

    DTIC Science & Technology

    2012-03-21

    Government that they could no longer control the situation and on May 24, 2006, East Timor’s Foreign Minister, José Ramos- Horta , requested assistance...culminating in a February 11, 2008 assassination attempt on President Gusmao and Prime Minister Jose Ramos Horta , during which the rebel leader...Conflict, Security & Development 9 (2 June 2009), 280. Prime Minister Jose Ramos Horta suffered three gunshot wounds to the torso and was regarded as

  10. Paleogene stratigraphy of the Solomons Island, Maryland corehole

    USGS Publications Warehouse

    Gibson, Thomas G.; Bybell, Laurel M.

    1994-01-01

    Purge and trap capillary gas chromatography/mass spectrometry is a rapid, precise, accurate method for determining volatile organic compounds in samples of surface water and ground water. The method can be used to determine 59 selected compounds, including chlorofluorohydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons. The volatile organic compounds are removed from the sample matrix by actively purging the sample with helium. The volatile organic compounds are collected onto a sorbant trap, thermally desorbed, separated by a Megabore gas chromatographic capillary column, ionized by electron impact, and determined by a full-scan quadrupole mass spectrometer. Compound identification is confirmed by the gas chromatographic retention time and by the resultant mass spectrum. Unknown compounds detected in a sample can be tentatively identified by comparing the unknown mass spectrum to reference spectra in the mass-spectra computer-data system library compiled by the National Institute of Standards and Technology. Method detection limits for the selected compounds range from 0.05 to 0.2 microgram per liter. Recoveries for the majority of the selected compounds ranged from 80 to 120 percent, with relative standard deviations of less than 10 percent.

  11. Crawling patterns in neglected poliomyelitis in the Solomon Islands.

    PubMed

    Cross, A B

    1977-11-01

    Two hundred and twenty-two adult crawling poliomyelitic cripples were investigated. Analysis showed that bilateral lower limb paralysis with or without trunk involvement was the most common residual lesion. Remarkably paralysis was confined to a single lower limb in six cases. The various crawling patterns can be classified into six broad groups which are described and illustrated. It is suggested that in a developing country this classification has a practical application in the assessment of patients for rehabilitation to crutch walking. Subjects in the "true quandruped progression" and "squatting gait" categories generally have an excellent potential for rehabilitation, as often do those in the "infant-like crawl" group. Caution should be exercised in attempting crutch walking for those in the "body-dragging" group, and there seems little indication for attempting to establish upright walking for those in the "buttock pivoting" and "minimal movement" groups.

  12. Defying Definition: Rethinking Education Aid Relationships in Solomon Islands

    ERIC Educational Resources Information Center

    Spratt, Rebecca

    2016-01-01

    The discourse of aid--its language, structures and practice--powerfully ascribes roles and attributes to those involved in aid relationships such as developed/developing, partner, recipient/donor etcetera. This discourse is driven by a complex system of diverse and often competing ideas, values, actors and relationships, within which individuals…

  13. 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. George’s 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.

  14. 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.

  15. Volcano Instability Induced by Resurgence at the Ischia Island Caldera (Italy), and the Tsunamigenic Potential of the Related Debris Avalanche Deposits: a Complex Source of Hazard at Land-sea Interface

    NASA Astrophysics Data System (ADS)

    Tinti, S.; Zaniboni, F.; Pagnoni, G.; Marotta, E.; Della Seta, M.; de Vita, S.; Orsi, G.; Sansivero, F.; Fredi, P.

    2009-05-01

    Slope instability is a common feature in the evolution of active volcanic areas. The occurrence of mass movements is doubly linked to volcanism and volcano-tectonism, which act as either preparing factor (through increased topographic gradients or emplacement of unconsolidated deposits on slopes) or triggering factor (through earthquakes and/or eruptions). Debris avalanches and lahars in active volcanic areas are an additional factor of hazard, due to their high destructive power. Moreover, volcanoes located in coastal areas or on islands, may experience lateral collapses with the potential to generate large tsunamis. Ischia is an active volcanic island in the Gulf of Naples. Volcanism begun prior to 150 ka and continued, with periods of quiescence, until the last eruption in 1302 A.D. It has been dominated by a caldera-forming eruption (55 ka), which was followed by resurgence of the caldera floor. Volcanism and gravitational mass movements have been coeval to resurgence, which generated a maximum net uplift of about 900 m over the past 33 ka. Resurgence occurred through intermittent uplifting and tectonic quietness phases. During uplift, volcanism and generation of mass movements were very active. The resurgent area is composed of differentially displaced blocks and has a poligonal shape, resulting from reactivation of regional faults and activation of faults directly related to volcano-tectonism. The western sector is bordered by inward-dipping, high-angle reverse faults, cut by late outward-dipping normal faults due to gravitational readjustment of the slopes. The north-eastern and the south-western sides are bordered by vertical faults with right transtensive and left transpressive movements, respectively. The area located to the east of the most uplifted block is displaced by outward- dipping normal faults. Some giant landslides and their relationships with volcano-tectonism have been recognized at Ischia. Their deposits are intercalated with primary

  16. 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.

  17. Evolution of elastic properties and acoustic emission, during uniaxial loading of rocks, from the Fogo Volcano in the island of Sao Miguel, Azores; Preliminary results.

    NASA Astrophysics Data System (ADS)

    Moreira, M.; Wallenstein, N.

    2012-04-01

    A Computerized Uniaxial Press working up to 250 kN was installed in the middle 2011 in the Laboratory of Microseismic Monitoring of ISEL. The system is able to record continuous time, pressure and axial strain (1 µm resolution) at 1s sampling rate. The loading platens were designed to integrate acoustic emission (AE) transducers. Signals are acquired and processed through an 8-channel ESG Hyperion Ultrasonic Monitoring System (10 MSPS, 14/16-bit ADC). The first experiments, presented here, were applied to a set of rock samples from the Fogo, an active central volcano in the island of Sao Miguel. Two different volcanic rock types were studied: a fine grained alkali basaltic rock with a porphyritic texture, a porosity of 4.5% and bulk density of 2700 kg m-3 (sample #3); and a benmoreitic rock with a trachytic texture, a porosity of 8.1 %, and bulk density of 2400 kg m-3 (sample #4). Cores from sample #3 were subjected to continuous increasing pressure, until failure. They show a uniaxial compressive strength (UCS) spanning from 60 to 85 MPa and a stress-strain curve with two phases: a first one with relative low Young's Module (YM) followed by a second phase were the YM increases roughly 3 times. The stress transition value occurs broadly in a stress level 50% of the UCS. The AE produced in the process is almost negligible until the YM transition stress level and increases after that. Important pulses of high AE rate occur, (> 100 s-1), associated with the occurrence and propagation of fractures, which are always parallel to the principal stress, showing an evident pattern of tensile fractures. About 20s before the failure, very important deformation rate is observed, the YM strongly decrease, and continuous AE events, with low rate, usually <50 s-1. The failure is accompanied with a sudden rise of AE events with rate > 200 s-1. Cycling stress experiences were also performed showing reversible stress-strain relation for axial pressure below the YM transition level

  18. Syrian Volcano

    NASA Technical Reports Server (NTRS)

    2006-01-01

    23 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small volcano in the Syria Planum region of Mars. Today, the lava flows that compose this small volcano are nearly hidden by a mantle of rough-textured, perhaps somewhat cemented, dust. The light-toned streaks that cross the scene were formed by passing dust devils, a common occurrence in Syria.

    Location near: 13.0oS, 102.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  20. Simplified Correction Of Errors In Reed-Solomon Codes

    NASA Technical Reports Server (NTRS)

    Truong, T. K.; Hsu, I. S.; Eastman, W. L.; Reed, I. S.

    1990-01-01

    New decoder realized by simplified pipeline architecture. Simplified procedure for correction of errors and erasures in Reed-Solomon codes expected to result in simpler decoding equipment. Development widens commercial applicability of Reed-Solomon codes, used to correct bursts of errors in digital communication and recording systems. Improved decoder less complex. Made more regular, simple, and suitable for implementation in both VLSI and software.

  1. Volcano Hazards Program

    USGS Publications Warehouse

    Venezky, Dina Y.; Myers, Bobbie; Driedger, Carolyn

    2008-01-01

    Diagram of common volcano hazards. The U.S. Geological Survey Volcano Hazards Program (VHP) monitors unrest and eruptions at U.S. volcanoes, assesses potential hazards, responds to volcanic crises, and conducts research on how volcanoes work. When conditions change at a monitored volcano, the VHP issues public advisories and warnings to alert emergency-management authorities and the public. See http://volcanoes.usgs.gov/ to learn more about volcanoes and find out what's happening now.

  2. Chikurachki Volcano

    Atmospheric Science Data Center

    2013-04-16

    ... southeast. The darker areas of the plume typically indicate volcanic ash, while the white portions of the plume indicate entrained water droplets and ice. According to the Kamchatkan Volcanic Eruptions Response Team (KVERT), the temperature of the plume near the volcano ...

  3. Palaeomagnetic study of a subaerial volcanic ridge (São Jorge Island, Azores) for the past 1.3 Myr: evidence for the Cobb Mountain Subchron, volcano flank instability and tectonomagmatic implications

    NASA Astrophysics Data System (ADS)

    Silva, P. F.; Henry, B.; Marques, F. O.; Hildenbrand, A.; Madureira, P.; Mériaux, C. A.; Kratinová, Z.

    2012-03-01

    We present a palaeomagnetic study on 38 lava flows and 20 dykes encompassing the past 1.3 Myr on S. Jorge Island (Azores Archipelago—North Atlantic Ocean). The sections sampled in the southeastern and central/western parts of the island record reversed and normal polarities, respectively. They indicate a mean palaeomagnetic pole (81.3°N, 160.7°E, K= 33 and A95= 3.4°) with a latitude shallower than that expected from Geocentric Axial Dipole assumption, suggesting an effect of non-dipolar components of the Earth magnetic field. Virtual Geomagnetic Poles of eight flows and two dykes closely follow the contemporaneous records of the Cobb Mountain Subchron (ODP/DSDP programs) and constrain the age transition from reversed to normal polarity at ca. 1.207 ± 0.017 Ma. Volcano flank instabilities, probably related to dyke emplacement along an NNW-SSE direction, led to southwestward tilting of the lava pile towards the sea. Two spatially and temporally distinct dyke systems have been recognized on the island. The eastern is dominated by NNW-SSE trending dykes emplaced before the end of the Matuyama Chron, whereas in the central/western parts the eruptive fissures oriented WNW-ESE controlled the westward growth of the S. Jorge Island during the Brunhes Chron. Both directions are consistent with the present-day regional stress conditions deduced from plate kinematics and tectonomorphology and suggest the emplacement of dykes along pre-existing fractures. The distinct timing and location of each dyke system likely results from a slight shift of the magmatic source.

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

    NASA Astrophysics Data System (ADS)

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

    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 Réunion), 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.

  5. Infrared surveys of Hawaiian volcanoes

    USGS Publications Warehouse

    Fischer, W. A.; Moxham, R.M.; Polcyn, F.; 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 issuing 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.

  6. Dengue virus type 3, South Pacific Islands, 2013.

    PubMed

    Cao-Lormeau, Van-Mai; Roche, Claudine; Musso, Didier; Mallet, Henri-Pierre; Dalipanda, Tenneth; Dofai, Alfred; Nogareda, Francisco; Nilles, Eric J; Aaskov, John

    2014-06-01

    After an 18-year absence, dengue virus serotype 3 reemerged in the South Pacific Islands in 2013. Outbreaks in western (Solomon Islands) and eastern (French Polynesia) regions were caused by different genotypes. This finding suggested that immunity against dengue virus serotype, rather than virus genotype, was the principal determinant of reemergence.

  7. 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, Gérard; 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. George’s 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.

  8. Maximum likelihood decoding of Reed Solomon Codes

    SciTech Connect

    Sudan, M.

    1996-12-31

    We present a randomized algorithm which takes as input n distinct points ((x{sub i}, y{sub i})){sup n}{sub i=1} from F x F (where F is a field) and integer parameters t and d and returns a list of all univariate polynomials f over F in the variable x of degree at most d which agree with the given set of points in at least t places (i.e., y{sub i} = f (x{sub i}) for at least t values of i), provided t = {Omega}({radical}nd). The running time is bounded by a polynomial in n. This immediately provides a maximum likelihood decoding algorithm for Reed Solomon Codes, which works in a setting with a larger number of errors than any previously known algorithm. To the best of our knowledge, this is the first efficient (i.e., polynomial time bounded) algorithm which provides some maximum likelihood decoding for any efficient (i.e., constant or even polynomial rate) code.

  9. Photobacterium galatheae sp. nov., a bioactive bacterium isolated from a mussel in the Solomon Sea.

    PubMed

    Machado, Henrique; Giubergia, Sonia; Mateiu, Ramona Valentina; Gram, Lone

    2015-12-01

    A novel, Gram-negative marine bacterium, S2753T, was isolated from a mussel of the Solomon Sea, Solomon Islands. Analysis of the 16S rRNA gene sequence and whole genome sequence data placed strain S2753T in the genus Photobacterium with the closest relative being Photobacterium halotolerans DSM 18316T (97.7 % 16S rRNA gene similarity). Strain S2753T was able to grow from 15 to 40 °C and in NaCl concentrations of 0.5 to 9 % (w/v). The predominant fatty acids were 16 : 1ω7c/16 : 1ω6c (27.9 %), 16 : 0 (22.1 %) and 18 : 1ω7c/8 : 1ω6c (21.4 %). The genomic DNA G+C mol content was 49.5 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic differences, strain S2753T is considered to represent a novel species of the genus Photobacterium. Furthermore, whole genome sequence analysis comparing S2753T and type-strains of closely related species of the genus Photobacterium also demonstrated that the strain is genomically distinct enough to be considered a novel species. The name Photobacterium galatheae is proposed and the type-strain is S2753T( = LMG 28894T = DSM 100496T).

  10. Mud Volcanoes Formation And Occurrence

    NASA Astrophysics Data System (ADS)

    Guliyev, I. S.

    2007-12-01

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

  11. 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

  12. A Direct Comparison of MODIS and COSPEC Sulfur Dioxide Measurements of the May 21, 2003 Eruption Plume of Anatahan Volcano, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Meier, V. L.; Scuderi, L.; Fischer, T.; Hilton, D.

    2007-05-01

    Quantifying the SO2 burden emitted from a volcano is critical to understanding a volcano's current state of activity. Ground-based instruments such as the correlation spectrometer (COSPEC) and the mini-DOAS are most routinely employed to measure volcanic SO2. Both instruments are human operated so they must be deployed on-site to obtain SO2 estimates. This makes it difficult and costly to regularly monitor active volcanoes world- wide. Satellite-based measurements, which can provide SO2 estimates in near real-time, have increasingly been used as a tool for volcanic monitoring. The Moderate Resolution Imaging Spectrometer (MODIS) located on board the Terra and Aqua satellites provides twice daily coverage of the Earth and has the capacity to detect volcanic SO2. The ability of MODIS to accurately detect and quantify SO2 in volcanic plumes using a SO2 retrieval program, MAP_SO2, was compared with COSPEC on the May 21, 2003 plume at Anatahan volcano (16.35oN, 145.67oE). MODIS was able to clearly detect SO2 in the plume and the MAP_SO2 derived SO2 flux was calculated (independently from the COSPEC data) to be more than twice the COSPEC derived flux (10,270 t/d and 3,000 - 4,500 t/d respectively). However, calculating a flux introduces additional errors. Therefore another means of comparing the two methods is utilized: a direct comparison of plume cross-sections from these two different methods. The MODIS image used with the MAP_SO2 program was acquired at 13:25 local time. The COSPEC traverse began at 13:35 local time and ended 14:40 local time. The time of the MODIS image acquisition and the start of the COSPEC traverse occurred within 10 minutes of each other. Although the MODIS image is a snap shot in time and the COSPEC traverse took about an hour to complete, the timing is so close that these two products are ideal for the comparison. The differences in these observations are used to better quantify SO2 emissions, to assess the current mismatch between ground

  13. 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.

  14. 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.

  15. New behaviour of the Piton de La Fournaise volcano feeding system (La Réunion Island) deduced from GPS data: Influence of the 2007 Dolomieu caldera collapse

    NASA Astrophysics Data System (ADS)

    Peltier, Aline; Staudacher, Thomas; Bachèlery, Patrick

    2010-04-01

    After 15 months of summit deflation, the unrest of Piton de La Fournaise renewed in August 2008 with several seismic crises and the re-pressurization of the plumbing system. The successive seismic crises, sometime accompanied by ground displacements detected by GPS, were associated with inter-eruptive dyke intrusions. It was the first time since the implementation of the observatory that such successive inter-eruptive magma migrations, not reaching the surface, were observed at Piton de La Fournaise. The change in the volcano activity, with an increase in the frequency of pure dyke intrusions, have followed the Dolomieu caldera collapse of April 2007 and reveals its strong influence on the new eruptive regime. Stress changes in the volcanic edifice have, temporarily at least, favoured the arrest of dykes in depth. During these successive dyke intrusions, magma stopped at shallow depth to form transitory magma storages before to erupt during three successive small summit eruptions (September 21st-October 2nd, 2008; November 27th; and December 14th, 2008-February 4th, 2009). The same kind of change in the pre-eruptive and eruptive behaviour can be expected on other volcanoes having experienced a summit caldera collapse.

  16. Sequence stratigraphy, structural style, and age of deformation of the Malaita accretionary prism (Solomon arc-Ontong Java Plateau convergent zone)

    NASA Astrophysics Data System (ADS)

    Phinney, Eric J.; Mann, Paul; Coffin, Millard F.; Shipley, Thomas H.

    2004-10-01

    Possibilities for the fate of oceanic plateaus at subduction zones range from complete subduction of the plateau beneath the arc to complete plateau-arc accretion and resulting collisional orogenesis. Deep penetration, multi-channel seismic reflection (MCS) data from the northern flank of the Solomon Islands reveal the sequence stratigraphy, structural style, and age of deformation of an accretionary prism formed during late Neogene (5-0 Ma) convergence between the ˜33-km-thick crust of the Ontong Java oceanic plateau and the ˜15-km-thick Solomon island arc. Correlation of MCS data with the satellite-derived, free-air gravity field defines the tectonic boundaries and internal structure of the 800-km-long, 140-km-wide accretionary prism. We name this prism the "Malaita accretionary prism" or "MAP" after Malaita, the largest and best-studied island exposure of the accretionary prism in the Solomon Islands. MCS data, gravity data, and stratigraphic correlations to islands and ODP sites on the Ontong Java Plateau (OJP) reveal that the offshore MAP is composed of folded and thrust faulted sedimentary rocks and upper crystalline crust offscraped from the Solomon the subducting Ontong Java Plateau (Pacific plate) and transferred to the Solomon arc. With the exception of an upper, sequence of Quaternary? island-derived terrigenous sediments, the deformed stratigraphy of the MAP is identical to that of the incoming Ontong Java Plateau in the North Solomon trench. We divide the MAP into four distinct, folded and thrust fault-bounded structural domains interpreted to have formed by diachronous, southeast-to-northwest, and highly oblique entry of the Ontong Java Plateau into a former trench now marked by the Kia-Kaipito-Korigole (KKK) left-lateral strike-slip fault zone along the suture between the Solomon arc and the MAP. The structural style within each of the four structural domains consists of a parallel series of three to four fault propagation folds formed by the

  17. 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

  18. Bathymetry and Canyons of the western Solomon Sea

    NASA Astrophysics Data System (ADS)

    Davies, H. L.; Keene, J. B.; Hashimoto, K.; Joshima, M.; Stuart, J. E.; Tiffin, D. L.

    1986-12-01

    The floor of the western Solomon Sea (for new bathymetric map see inside back cover of this issue) is dominated by the arched and ridged basement of the Solomon Sea Basin, the partly-sediment-filled New Britain Trench, and a more completely filled trench, the Trobriand Trough. There is a deep basin where the trenches join (149° Embayment), and a silled basin west of the New Britain Trench (Finsch Deep). Submarine canyons descend from the west and south to the 149° Embayment. Abyssal fans and plains are structurally defined and locally disturbed by young faults. Probable submerged pinnacle reefs stand in water depths as great as 1,200 m.

  19. Monitoring active volcanoes

    USGS Publications Warehouse

    Tilling, Robert I.

    1987-01-01

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

  20. Prodigious emission rates and magma degassing budget of major, trace and radioactive volatile species from Ambrym basaltic volcano, Vanuatu island Arc

    NASA Astrophysics Data System (ADS)

    Allard, P.; Aiuppa, A.; Bani, P.; Métrich, N.; Bertagnini, A.; Gauthier, P.-J.; Shinohara, H.; Sawyer, G.; Parello, F.; Bagnato, E.; Pelletier, B.; Garaebiti, E.

    2016-08-01

    Ambrym volcano, in the Vanuatu arc, is one of the most active volcanoes of the Southwest Pacific region, where persistent lava lake and/or Strombolian activity sustains voluminous gas plume emissions. Here we report on the first comprehensive budget for the discharge of major, minor, trace and radioactive volatile species from Ambrym volcano, as well as the first data for volatiles dissolved in its basaltic magma (olivine-hosted melt inclusions). In situ MultiGAS analysis of H2O, CO2, SO2 and H2S in crater rim emissions, coupled with filter-pack determination of SO2, halogens, stable and radioactive metals demonstrates a common magmatic source for volcanic gases emitted by its two main active craters, Benbow and Marum. These share a high water content ( 93 mol%), similar S/Cl, Cl/F, Br/Cl molar ratios, similar (210Po/210Pb) and (210Bi/210Pb) activity ratios, as well as comparable proportions in most trace metals. Their difference in CO2/SO2 ratio (1.0 and 5.6-3.0, respectively) is attributed to deeper gas-melt separation at Marum (Strombolian explosions) than Benbow (lava lake degassing) during our measurements in 2007. Airborne UV sensing of the SO2 plume flux (90 kg s- 1 or 7800 tons d- 1) demonstrates a prevalent degassing contribution ( 65%) of Benbow crater in that period and allows us to quantify the total volatile fluxes during medium-level eruptive activity of the volcano. Results reveal that Ambrym ranks among the most powerful volcanic gas emitters on Earth, producing between 5% and 9% of current estimates for global subaerial volcanic emissions of H2O, CO2, HCl, Cu, Cr, Cd, Au, Cs and Tl, between 10% and 17% of SO2, HF, HBr, Hg, 210Po and 210Pb, and over 30% of Ag, Se and Sn. Global flux estimates thus need to integrate its contribution and be revised accordingly. Prodigious gas emission from Ambrym does not result from an anomalous volatile enrichment nor a differential excess degassing of its feeding basalt: this latter contains relatively modest

  1. Seismogenic structures activated during the pre-eruptive and intrusive swarms of Piton de la Fournaise volcano (La Réunion island) between 2008 and 2011

    NASA Astrophysics Data System (ADS)

    Battaglia, J.; Brenguier, F.

    2011-12-01

    Piton de la Fournaise is a frequently active basaltic volcano with more than 30 fissure eruptions since 1998. These eruptions are always preceded by pre-eruptive swarms of volcano-tectonic earthquakes which accompany dike propagation. Occasionally, intrusion swarms occur without leading to any eruption. From October 2008 to May 2011, as part of the research project Undervolc, a temporary network of 15 broadband stations has been installed on the volcano to complement the local monitoring network. We examined in detail the 6 intrusive and 5 pre-eruptive swarms which occurred during the temporary experiment. All the crises lasted for a few hours and only included shallow events clustered below the summit craters, around and above sea level, showing no signs of deeper magma transfers. These characteristics are common to most swarms observed at Piton de la Fournaise arising questions about the origin of the seismicity which seems to be poorly linked with dike propagation. With the aim to identify the main seismogenic structures active during the swarms, we applied precise earthquake detection and classification techniques based on waveform cross-correlation. For each swarm, the onsets of all transients, including small amplitude ones, have been precisely detected at a single station by scanning the continuous data with reference waveforms. The classification of the detected transients indicates the presence of several families of similar earthquakes. The two main families (F01 and F02) include several hundred events. They are systematically activated at the beginning of each pre-eruptive swarm but are inactive during the intrusive ones. They group more than 50 percent of the detected events for the corresponding crises. The other clusters are mostly associated with single swarms. To determine the spatial characteristics of the structures corresponding to the main families, we applied precise relocation techniques. Based on the one-station classification, the events

  2. "Canary Islands, a volcanic window in the Atlantic Ocean": a 7 year effort of public awareness on volcano hazards and risk management

    NASA Astrophysics Data System (ADS)

    Rodríguez, Fátima; Calvo, David; Pérez, Nemesio M.; Padrón, Eleazar; Melián, Gladys; Padilla, Germán; Barrancos, José; Hernández, Pedro A.; Asensio-Ramos, María; Alonso, Mar

    2016-04-01

    "Canary Islands: A volcanic window in the Atlantic Ocean" is an educational program born from the need to inform and educate citizens residing in the Canary Islands on the various hazards associated to volcanic phenomena. The Canary Islands is the only territory of Spain that hosts active volcanism, as is shown by the 16 historical eruptions that have occurred throughout this territory, being the last one a submarine eruption taking place on October 12, 2011, offshore El Hierro Island. In the last 7 years, ITER as well as INVOLCAN have been performing an educative program focused on educating to the population about the benefits of a volcanic territory, volcanic hazards, how to reduce volcanic risk and the management of volcanic risk in the Canary Islands. "Canary Islands: A volcanic window in the Atlantic Ocean" consists of three units, the first two dedicated to the IAVCEI/UNESCO videos "Understanding Volcanic Hazards" and "Reducing Volcanic Risk" and the third one dedicated to the management of volcanic risk in the Canary Islands, as well as some other aspects of the volcanic phenomena. Generally the three units are shown consecutively on Tuesday, Wednesday and Thursday. This educative program has been roaming all around the 88 municipalities of the archipelago since this initiative started in 2008. The total number of attendees since then amounts to 18,911 people. The increase of assistance was constant until 2011, with annual percentages of 7.8, 17.1 and 20.9 respectively, regarding to ratio assistant/municipality. Despite the heterogeneity of the audience, the main audience is related to aged people of 45 years and older. This could be related to the memories of the recent eruptions occurred at La Palma Island in 1949 and 1971. It is important to point out that many of those people attending the educative program are representatives of local government (i.e. civil protection). Regarding the interest of the audience, the educational program attendees have

  3. 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

  4. Radial anisotropy ambient noise tomography of volcanoes

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  5. 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.

  6. 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.

  7. The Submarine Flanks of Anatahan Volcano

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    The submarine flanks of Anatahan volcano were surveyed with EM300 multibeam sonar and the MR1 sidescan sonar from the R/V Thomas G. Thompson in February 2003. This was part of a larger survey of over 50 submarine volcanoes within the Marianas volcanic arc between 13° 10'N and 23° 10'N (see Embley et al. and Baker et al. abstracts, this meeting). This work was part of a multi-year study of seafloor volcanism in diverse tectonic settings, funded by NOAA's Office of Ocean Exploration. (see: http://oceanexplorer.noaa.gov/explorations/03fire/). The island of Anatahan has a maximum elevation of 798 m, but its submarine flanks descend to depths of 2000-2600 m, so most of the volcano lies below sea level. The submarine part of the volcano is elongated in the east-west direction, like the island. Conspicuous in the bathymetry are numerous small parasitic cones and hummocky ridges on the southwest and east submarine flanks of the island that radiate outward (downslope) from the island. These features appear as areas of high reflectivity in the MR1 sidescan sonar and some have distinctly lobate outlines, suggesting that they are areas of relatively young lava flows. Some of these lava flows extend up to 15 km from the coastline of the island and to depths below 2000 m. The upslope sources of these lavas are often ambiguous, but we interpret that they were erupted underwater (as opposed to erupted on land and then flowing into the ocean) because they are associated with cones and ridges that may be vent areas. The other flanks of the island appear to be draped in volcaniclastic material that has been transported downslope from the shoreline, in some cases as distinct flows that radiate outward in braided channels that have slightly higher reflectivity than surrounding areas in the sidescan imagery. These fragmental flows also extend to depths below 2000 m, especially on the west and south flanks of the island. The most prominent feature in the bathymetry around Anatahan is a

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

    USGS Publications Warehouse

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

    2014-01-01

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

  9. 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.

  10. First cross-correlated measurements of magma dynamics and degassing during a dyke eruption at Piton de la Fournaise hot spot volcano, Reunion island

    NASA Astrophysics Data System (ADS)

    Allard, P.; La Spina, A.; Tamburelllo, G.; Aiuppa, A.; Coquet, A.; Brenguier, F.; Coppola, D.; Di Muro, A.; Burton, M. R.; Staudacher, T.

    2011-12-01

    Piton de la Fournaise (PdF), in the western Indian Ocean, is a very active hot spot basaltic volcano whose eruptions (1-2 per year on average) are well anticipated by the local seismic-geodetic monitoring network. Here we report on the first cross-correlated measurements of seismic tremor, magmatic gas composition (OP-FTIR absorption spectroscopy and in situ MultiGas analysis plus filter-pack sampling), gas fluxes (DOAS) and magma extrusion rate (space-borne MODIS data) during a 2-weeks long dyke eruption at PDF in October 2010. Precursory seismic signals indicated dyke ascent in a few hours from a reservoir located at ~2.5 km beneath the summit crater. After an initial burst coinciding with eruptive fissure opening, both the tremor amplitude, lava extrusion rate and SO2 flux coherently decreased during the first week of eruption. The co-emitted magmatic gases, whose composition varied slightly over time, were found to have a high water content (95-98 mol %), high SO2/HCl and low CO2/SO2, HCl/HF and Cl/Br ratios, consistent with a hydrous hot spot mantle source. By comparing gas fluxes with the magma co-extrusion rate and available melt inclusion data, we infer an essentially syn-eruptive (closed system) degassing for sulfur, chlorine and fluorine during the first half of the eruption. In contrast, additions of CO2 (previously accumulated or/and bubbling differentially) and H2O (external contribution from the hydrothermal system?) are required to explain the gas composition. Differential CO2 bubbling is supported by high frequency correlations between the CO2/HCl ratio and seismic tremor. The second part of the eruption was marked by a spectacular decoupling between re-increasing seismic tremor and declining lava extrusion, indicating a key control of tremor and eruptive activity by differential (open system) gas bubbling across the feeder dyke. This was associated with an increasing contribution of the low-frequency (1-3 Hz) spectral band to the tremor amplitude

  11. 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.

  12. 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

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  14. Spreading and collapse of big basaltic volcanoes

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  15. 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

  16. 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

  17. 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

  18. Scientists probe Earth’s secrets at the Hawaiian Volcano Observatory

    USGS Publications Warehouse

    Unger, J.D.

    1974-01-01

    The Hawaiian Volcano Observatory (HVO) sits on the edge of Kilauea Caldera at the summit of Kilauea Volcao, one of the five volcanoes on the island of Hawaii, the largest island in the Hawaiian Islands chain. Of the five, only Kilauea and Mauna Loa have been active in the past 100 years. Before its last eruption in June 1950, Mauna Loa had erupted more frequently and copiously than Kilauea, but since then only Kilauea has been active. 

  19. 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.

  20. 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.

  1. Spreading And Collapse Of Big Basaltic Volcanoes

    NASA Astrophysics Data System (ADS)

    Puglisi, G.; Bonforte, A.; Guglielmino, F.; Peltier, A.; Poland, M. P.

    2015-12-01

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

  2. 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.

  3. 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.

  4. Revealing the magmas degassing below closed-conduit active volcanoes: noble gases in 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

    With the aim to constrain the nature of magma currently feeding the fumarolic field of Vulcano, we measured the elemental and isotopic compositions of noble gases (He, Ne, and Ar) in olivine- and clinopyroxene-hosted fluid inclusions in high-K calcalcaline-shoshonitic and shoshonitic-potassic series so as 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 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 record 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-emitted Vulcanello latites (Punta del Roveto), which have high He- and Sr-isotope ratios. This anomaly has been attributed to a flushing process by fluids coming from the deepest reservoirs. Indeed, 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 showed 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 that the most probable magma which actually feeds the fumarolic emissions is a latitic body ponding at about 3-3.5 km of depth and flushed by fluids coming from a deeper and basic magma.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Focus: alien volcanos

    NASA Astrophysics Data System (ADS)

    Carroll, Michael; Lopes, Rosaly

    2007-03-01

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

  10. 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)

  11. 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.

  12. Custom CMOS Reed Solomon coder for the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Whitaker, S.; Cameron, K.; Owsley, P.; Maki, G.

    1990-01-01

    A VLSI coder is presented that can function either as an encoder or decoder for Reed-Solomon codes. VLSI is one approach to implementing high-performance Reed-Solomon decoders. There are three VLSI technologies that could be used: gate arrays, standard cells, and full custom. The first two approaches are relatively easy to implement, but are limited in both performance and density. Full-custom VLSI is used to achieve both circuit density and speed, and allows control of the amount of interconnect. Speed, which is a function of capacitance, which is a function of interconnect, is an important parameter in high-performance VLSI. A single 8.2 mm x 8.4 mm, 200,000 transistor CMOS chip implementation of the Reed-Solomon code required by the Hubble Space Telescope is reported. The chip features a 10-MHz sustained byte rate independent of error pattern. The 1.6-micron CMOS integrated circuit has complete decoder and encoder functions and uses a single data/system clock. Block lengths up to 255 bytes and shortened codes are supported with no external buffering. Erasure corrections and random error corrections are supported with programmable correction of up to 10 symbol errors. Correction time is independent of error pattern and the number of errors in the incoming message.

  13. SRA: Description of the Solomon System as Used for MUC-5

    DTIC Science & Technology

    1993-08-01

    joint venture texts, SRA ’s NLP core system, SOLOMON, has been under development since 1986. It has been used for a variety of domains, and was aimed from the start to be language-independent, domain-independent, and application-independent. More recently, SOLOMON has been extended to be multilingual, beginning with Spanish in 1990 and Japanese in 1991 The Spanish-Japanese text understanding system that uses SOLOMON was developed for a domain very different from the MUC-5 joint venture domain ( cf. Aone, et aL [2]), SOLOMON’s principal

  14. Pyroclastic flows and lavas of the Mogan and Fataga formations, Tejeda Volcano, Gran Canaria, Canary Islands: mineral chemistry, intensive parameters, and magma chamber evolution

    NASA Astrophysics Data System (ADS)

    Crisp, Joy A.; Spera, Frank J.

    1987-12-01

    The Mogan and Fataga formations on the island of Gran Canaria, Canary Islands, represent a sequence of approximately 30 intercalated pyroclastic and lava flows (total volume about 500 km3 dense-rock equivalent) including subalkaline rhyolitic, peralkaline rhyolitic and trachytic pyroclastic flows, nepheline trachyte lavas and a small volume of alkali basaltic lavas and tephra deposits. The eruption of the intermediate to silicic rocks of the Mogan and Fataga formations follows the roughly 4 Ma duration of basaltic shield volcanism. The most common assemblage in the evolved (Mogan and Fataga) rocks is anorthoclase+ edenitic amphibole+ilmenite+magnetite±augite±hypersthene +apatite+pyrrhotite. A few flows also contain plagioclase, biotite, or sphene. Coexisting Fe-Ti oxides yield equilibrium temperatures between 835 and 930° C and logf_{O_2 } between -11.2 and -12.6. The lowermost pyroclastic flow of the Mogan formation is zoned from a rhyolitic base (848° C) to a basaltic top (931° C). Unit P1 has an oxygen isotope feldspar-magnetite temperature (850° C) very close to its Fe-Ti oxide temperature. One of the youngest Mogan flows is zoned from a comendite (836° C) at the base to a comenditic trachyte (899° C) at the top. The Fataga formation pyroclastic flows show only slight compositional zonation, and one flow has the same Fe-Ti oxide compositions at top and base. Calculations using the reaction 1/3 magnetite+SiO2 (melt)=ferrosilite+1/6 O2 indicate total pressures of 1 4 (±3) kb for six of the Mogan flows and one of the Fataga flows. For four of the pyroclastic flows, equilibria involving tremolite-SiO2-diopside-enstatite-H2O and phlogopite-SiO2-sanidine-enstatite-H2O imply water contents of 0.9 to 2.6 (±0.5) wt% andf_{H_2 O} between 80 and 610 bars, which indicates that magma within the Tejeda reservoir was H2O-undersaturated throughout the entire history of Mogan to Fataga volcanism. The fluorine contents of amphibole, biotite, and apatite, and chlorine

  15. Volcano Seismology

    NASA Astrophysics Data System (ADS)

    Chouet, B.

    - 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

  16. 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

  17. 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/.

  18. 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.

  19. 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.

  20. 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

  1. Lahar Hazards at Concepción volcano, Nicaragua

    USGS Publications Warehouse

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

    2001-01-01

    Concepción is one of Nicaragua’s highest and most active volcanoes. The symmetrical cone occupies the northeastern half of a dumbbell shaped island called Isla Ometepa. The dormant volcano, Maderas, occupies the southwest half of the island. A narrow isthmus connects Concepción and Maderas volcanoes. Concepción volcano towers more than 1600 m above Lake Nicaragua and is within 5 to 10 km of several small towns situated on its aprons at or near the shoreline. These towns have a combined population of nearly 5,000. The volcano has frequently produced debris flows (watery flows of mud, rock, and debris—also known as lahars when they occur on a volcano) that could inundate these nearby populated areas. Concepción volcano has erupted more than 25 times in the last 120 years. Its first recorded activity was in AD 1883. Eruptions in the past century, most of which have originated from a small summit crater, comprise moderate explosions, ash that falls out of eruption plumes (called tephra), and occasional lava flows. Near the summit area, there are accumulations of rock that were emplaced hot (pyroclastic deposits), most of which were hot enough to stick together during deposition (a process called welding). These pyroclastic rocks are rather weak, and tend to break apart easily. The loose volcanic rock remobilizes during heavy rain to form lahars. Volcanic explosions have produced blankets of tephra that are distributed downwind, which on Isla Ometepe is mostly to the west. Older deposits at the west end of the island that are up to 1 m thick indicate larger explosive events have happened at Concepción volcano in prehistoric time. Like pyroclastic-flow deposits, loose tephra on the steep slopes of the volcano provides source material that heavy rainstorms and earthquakes can mobilize to trigger debris flow.

  2. 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

  3. 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