Note: This page contains sample records for the topic volcano solomon islands from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

The role of slab melting in the petrogenesis of high-Mg andesites: evidence from Simbo Volcano, Solomon Islands  

Microsoft Academic Search

The petrogenesis of high-Mg andesites (HMA) in subduction zones involves shallow melting of refractory mantle sources or, alternatively, the interaction of ascending slab-derived melts with mantle peridotite. To unravel the petrogenesis of HMA, we report major, trace element and Sr–Nd–Hf–Pb isotope data for a newly found occurrence of HMA in the New Georgia group, Solomon Islands, SW-Pacific. Volcanism in the

S. König; S. Schuth; C. Münker; C. Qopoto

2007-01-01

2

Flood and landslide hazard mapping, Solomon Islands  

Microsoft Academic Search

Cyclone Namu in 1986 highlighted the enormity of the risk to life and property on Guadalcanal from natural hazards. Buildings, roads, bridges, crops, and forests were destroyed and at least 100 people were killed. An aerial photographic reconnaissance survey of the two most severely damaged islands, Guadalcanal and Malaita, was undertaken three months after the storm. To assist the Solomon

N. A. TRUSTRUM; I. E. WHITEHOUSE; P. M. BLASCHKE; P. R. STEPHENS

1990-01-01

3

Solomon Islands Tsunami, One Year Later  

Microsoft Academic Search

The geologic and economic effects of the 2 April 2007 Solomon Islands earthquake and tsunami are distinctly visible a little more than a year after the event. Coral reef colonies that were sheared off and uplifted are slowly recovering, and many new earthquake-triggered landslides remain mobile. Large volumes of sediment created by the earthquake and mobilized by the tsunami have

Brian G. McAdoo; Hermann Fritz; Kelly L. Jackson; Nikos Kalligeris; Jens Kruger; Michael Bonte-Grapentin; Andrew L. Moore; Wilson B. Rafiau; Douglas Billy; Braddley Tiano

2008-01-01

4

Solomon Island Nongovernment Organizations: Major Environmental Actors  

Microsoft Academic Search

The immediate challenge faced by both the Solomon Islands Govern- ment and nongovernment organizations working in development and envi- ronmental matters is how to equitably deliver pertinent insights, infor- mation, and services to almost 400,000 people living in 5500 widely dispersed villages, many of which are in the highlands and interior low- lands, with forbidding terrains and accessible only by

John Roughan

5

Constitutional crisis in the Solomon Islands  

Microsoft Academic Search

In October 1994, following a series of defections from the governing coalition, the Governor?General of the Solomon Islands attempted to dismiss Prime Minister Hilly on grounds that the latter no longer had a majority in Parliament. Hilly said he had no power to take such action and challenged it in the courts, meanwhile remaining in office. Court of Appeal ruled

Roger Barltrop

1995-01-01

6

Vernacular Literacy in the Touo Language of the Solomon Islands  

ERIC Educational Resources Information Center

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…

Dunn, Michael

2005-01-01

7

Solomon Islands Tsunami, One Year Later  

NASA Astrophysics Data System (ADS)

The geologic and economic effects of the 2 April 2007 Solomon Islands earthquake and tsunami are distinctly visible a little more than a year after the event. Coral reef colonies that were sheared off and uplifted are slowly recovering, and many new earthquake-triggered landslides remain mobile. Large volumes of sediment created by the earthquake and mobilized by the tsunami have been flushed from the lagoons between the reef and shoreline into deeper water, although significant quantities remain on land. Sediment from the lagoons covers piles of shattered coral that the tsunami moved from the lagoons to the base of channels in the barrier reef. These shattered corals have a higher chance of preservation as paleotsunami deposits than the material deposited on land.

McAdoo, Brian G.; Fritz, Hermann; Jackson, Kelly L.; Kalligeris, Nikos; Kruger, Jens; Bonte-Grapentin, Michael; Moore, Andrew L.; Rafiau, Wilson B.; Billy, Douglas; Tiano, Braddley

2008-04-01

8

Paradoxes of postcolonial police-building: Solomon Islands  

Microsoft Academic Search

Drawing upon recent fieldwork, we examine the paradoxical effects of the institutional transfer and capacity-building approach adopted by the ongoing regional intervention in post-conflict Solomon Islands. Taking the mission's substantial police-building component as our focus, we argue that this engagement has done little to extend the functional authority of the local police in rural Solomon Islands and has, moreover, induced

Sinclair Dinnen; Matthew Allen

2012-01-01

9

Some Soils of the British Solomon Islands Protectorate  

Microsoft Academic Search

Soils were studied on the islands of Guadalcanal, Kolombangara, Santa Isabel, San Jorge, and San Cristobal, mainly under tropical rain forest in mountainous inland regions. The climate of the Solomon Islands is characterized by high temperatures and humidity, copious rain and a high proportion of cloudy days, with little seasonal variation except in the rainfall of the central coastal region

K. E. Lee

1969-01-01

10

Stimulating investment in pearl farming in Solomon Islands: Final report  

Microsoft Academic Search

The overall objective of the project is the reduction of poverty in rural areas of Solomon Islands through creation of livelihoods based on sustainable aquaculture. This fits within the over-arching goals of the WorldFish Center in the Pacific to reduce poverty and hunger in rural communities, and with the Ministry of Fisheries and Marine Resources (MFMR) to stimulate rural development

11

The status of primary physical education in Solomon Islands  

Microsoft Academic Search

Through an analysis of 81 primary teachers' questionnaire responses, 16 interviews and three weeks observation of a school's physical activities, this paper attempts to depict the status of primary physical education in the Solomon Islands and to ascertain the extent to which teachers are confident in following the PE syllabus. School intramural and inter-school sport programmes were also surveyed. The

Jeremy Dorovolomo

12

Aid for education in post-conflict Solomon Islands  

Microsoft Academic Search

Between 1998 and 2003, conflict, violent crime, and a severe economic downturn pushed the Solomon Islands state to the brink\\u000a of failure, exacerbating the problems of an already struggling education sector. Most schools on Guadalcanal were seriously\\u000a disrupted; some were burned down or vandalized, others closed as teachers and students fled violence, and those that remained\\u000a open struggled to accommodate

Jeni Whalan; UNESCO IBE

2011-01-01

13

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

PubMed

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

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

2010-10-01

14

Deaths in natural hazards in the solomon islands.  

PubMed

Archival and library search techniques have been used to establish extensive databases on deaths and damage resulting from natural hazards in the Solomon Islands. Although the records of fatalities are certainly incomplete, volcanic eruptions, tropical cyclones, landslides, tsunami and earthquakes appear to have been the most important. Only 22 per cent of the recorded deaths have resulted from meteorological hazards but a single event could change this proportion significantly. Five events in the fatality database account for 88 per cent of the recorded deaths. Future death tolls are also likely to be dominated by a small number of events. While the expected number of deaths in a given period is dependent upon the length of record considered, it is clear that a disaster which kills one hundred or more people in the Solomons can be expected more frequently than once in a hundred years. PMID:20958753

Blong, R J; Radford, D A

1993-03-01

15

Tsunami awareness saves Solomon Islanders on 1 April 2007  

NASA Astrophysics Data System (ADS)

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.

Fritz, H. M.; Kalligeris, N.

2007-12-01

16

TECHNOLOGY EDUCATION TEACHER DEVELOPMENT IN SOLOMON ISLANDS: ENHANCING TEACHERS' PERCEPTIONS AND CLASSROOM PRACTICES  

Microsoft Academic Search

Technology education in the Solomon Islands is in the process of change with the curriculum being developed into a more broad technological literacy approach, comprising of technological knowledge, technological practices, and the nature of technology. This paper is based on a two-year study (2005 and 2006) with 8 secondary technology education teachers in the Solomon Islands. The first year of

D. Sade; J. Moreland; A. Jones

17

‘I Was Like Abraham’: notes on the anthropology of Christianity from the Solomon Islands  

Microsoft Academic Search

This article offers a detailed exegesis of what I term the ethno-theology of Timothy Karu, a Solomon Islands Anglican whose understanding of the nature of his matrilineage is informed by the Pauline account of the election of Israel. The analysis suggests a non-essentialising treatment of Christianity that nevertheless demonstrates how Solomon Islanders engage simultaneously with multiple interlocking macro and micro

Michael W. Scott

2005-01-01

18

A survey of village poultry production in the Solomon Islands.  

PubMed

A total of 84 farmers in 31 villages of Guadalcanal, Western, Malaita and Central Provinces of the Solomon Islands were surveyed to obtain baseline information on the current feeding practices and farmer attitudes to village poultry production. Farming of village chickens in the Solomon Islands is conducted on a small scale. Most surveyed farmers thought chickens were easy to care for, provide food for the family and was a good cash income enterprise. Some farmers were interested in keeping local chickens, but found it difficult to obtain the birds. The main feed sources are fresh coconut, copra meal, fish meal, mill run, food scraps and forage sources from the range. Some villagers believe that chickens only need to eat household scraps and did not provide drinking water. Many villagers lacked the knowledge of managing a village poultry enterprise. Some chicken houses were built by using bush materials or by purchasing construction materials. Farmers indicated they would like the government to provide funds for establishing a smallholder poultry enterprise and to provide information on feeding and management of birds. PMID:19242817

Jansen, T; Glatz, P C; Miao, Z H

2009-02-26

19

Mitigating the Risk to Primitive Accumulation: State-building and the Logging Boom in Solomon Islands  

Microsoft Academic Search

In recent years, various forms of inter\\/transnational state-building have become increasingly common as a way of managing the perceived risk posed by dysfunctional governance in so-called fragile states to Western security. In Solomon Islands, the Australian government has led a robust and expansive regional intervention, designed to build the capacity of the Solomon Islands government and bureaucracy to provide more

Shahar Hameiri

2012-01-01

20

Scale, Sovereignty, Wealth and Enterprise: Social and Educational Comparisons between the Cook Islands and the Solomon Islands.  

ERIC Educational Resources Information Center

Compares the Cook Islands (a small Pacific Island country) and the Solomon Islands (one of the largest) with regard to availability of postcompulsory education. Suggests that postschool educational benefits are positively associated with smallness (resulting in higher per capita international aid), per capita income, foreign investment,…

Crocombe, Ron; Crocombe, Marjorie Tuainekore

1993-01-01

21

The eruptive history and volcanic hazards of Savo, Solomon Islands  

NASA Astrophysics Data System (ADS)

Savo Island is the 6-km-diameter emergent summit of an andesitic-dacitic stratovolcano, rising from the Iron Bottom Sound, 35 km NW of Honiara, Solomon Islands. Savo has erupted at least three times within recorded history and the 3,000 inhabitants maintain extensive oral traditions of past events. Through description and interpretation of the volcaniclastic sequences on the island, in conjunction with historical accounts and oral traditions, we reconstruct the eruptive processes on Savo. Block-and-ash flow (BAF) deposits are volumetrically dominant on the island within three main depositional environments: near-vent sequences, thick medial channel sequences and distal fan sequences. The deposits comprise universally non-vesicular and highly porphyritic (40-70% phenocrysts), high-silica andesite and dacite clasts. These appear to have been derived from collapsing lava domes during an 1560-1570 A.D. eruption. However, eyewitness descriptions and crater morphology suggest that similar deposits formed from dome explosions or collapses of eruption columns during later eruptions (1830-1840 A.D.). The high-sodium magmas (ca. 5-7 wt% Na2O) apparently crystallised and strongly degassed prior to eruption. Shallow explosions were possibly caused by entrapment of magmatic gases beneath a dome or conduit plug of highly crystalline, near solid magma. Repeated sealing of the vent may have been due to inward collapse of the highly altered rocks of the surrounding hydrothermal system; these rocks probably were saturated due to contemporaneous high intensity rainfall events. BAFs were hot enough to char vegetation and attain aligned clast TRM (thermal remnant magnetism) up to 3 km from the vent, many being accompanied by ash-cloud surges. Changes with distance in the BAF deposits appear mostly dependent on flow confinement and are limited to an overall decrease in thickness and maximum clast size, and an increased definition of weak planar fabrics. In distal fan sequences, there is strong evidence for syn- and post-eruptive redeposition of primary deposits. Since the Savo population is concentrated on coastal volcaniclastic fans, we consider the greatest volcanic risk to life is from BAFs, associated ash-cloud surges and lahars. Hence, the main channels and fans are designated as the highest of three relative hazard zones on a simple map prepared to aid local education and planning initiatives on Savo.

Petterson, M. G.; Cronin, S. J.; Taylor, P. W.; Tolia, D.; Papabatu, A.; Toba, T.; Qopoto, C.

2002-11-01

22

Solomon Islands Pijin: Special Skills Handbook. Peace Corps Language Handbook Series.  

ERIC Educational Resources Information Center

This handbook is intended to acquaint Peace Corps volunteers with the geography and culture of the Solomon Islands. It is divided into five parts: (1) an atlas of pen-and-ink maps of the islands; (2) custom stories in Pijin, with an English translation of each one; (3) miscellaneous readings in Pijin; (4) posters in Pijin; and (5) a picture…

Huebner, Thom, Comp.

23

The serological status of Solomon Island blood donors.  

PubMed

The serological status of Solomon Island blood donors in 1995 and in particular the seroprevalence of antibodies to Hepatitis B and C and prevalence of risk factors for these chronic infections was studied. A questionnaire of risk factors for Hepatitis B and C was undertaken. All blood donors had been previously screened for HIV antibody without any positive cases recorded. 598 donors had serum collected of which 36 samples (6.0%) were third generation HCV EIA antibody positive and 3 samples were RIBA positive but none were PCR positive. 25.1% of samples were positive for HBsAg and anti-HBc antibody was found in 84.4%. Elevated ALT levels (>35 U/l) were found in 6.5% of samples but there was no statistically significant association with HCV or HBsAg status. 15.4% were TPHA positive and 5.4% had RPR titers more than or equal to 1. Anti-HTLV-1 antibody was positive in 12.3% randomly selected samples. All 10 positive samples were then found to be antibody indeterminate with Western blot assay. Of the 585 samples with completed questionnaires, analysis of the relationship between anti-HCV status with tattoo status and ear piercing also failed to reach statistical significance. Consistent with other studies from tropical malaria-prone countries, a positive anti-HCV antibody test even by the third generation EIA is probably a false positive test in most cases. In addition, high prevalence rates of HBV, yaws or syphilis infection were demonstrated. PMID:10774666

Lucas, R E; Faoagali, J L

1999-09-01

24

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

ERIC Educational Resources Information Center

|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…

de Guzman, Sylvia

2007-01-01

25

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

PubMed

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 this region. PMID:21771715

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

2011-07-18

26

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

ERIC Educational Resources Information Center

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…

Maebuta, Jack

2011-01-01

27

Butyltin Residues in Fish From Australia, Papua New Guinea and the Solomon Islands  

Microsoft Academic Search

Concentrations of mono- (MBT), di- (DBT) and tributyltin (TBT) were determined in the muscle and liver of fish collected from Australia, Papua New Guinea and the Solomon Islands. Butyltin concentrations ranged from below the limit of detection to 47 ng g in muscle and 6.5 to 570 ng g wet wt in liver. Liver was found to accumulate higher concentrations

K. Kannan; S. Tanabe; R. Tatsukawa; R. J. Williams

1995-01-01

28

Key and checklist for the lichen family Graphidaceae (lichenised Ascomycota) in the Solomon Islands  

Microsoft Academic Search

A checklist and keys are given for the 16 genera in the lichen family Graphidaceae found in the Solomon Islands. A total of 75 species in the family Graphidaceae were identified, distributed as follows: Acanthothecis two species, Anomomorpha one species, Carbacanthographis three species, Diorygma six species, Dyplolabia one species, Fissurina 11 species, Graphis 17 species, Hemithecium four species, Leiorreuma four

Alan W. Archer

2007-01-01

29

Genealogy as a Genre of Historicity: Gender and Contesting Histories in a Changing Solomon Islands Society  

Microsoft Academic Search

By rethinking genealogy as a dialogic genre of historicity, this paper examines the dynamics of genealogy in memorizing, representing and contesting ancestral histories among the Langalanga, Solomon Islands, particularly from the gender perspective. The Langalanga concept of genealogy—futana—lit. birth, is related to patrilineal descent ideology, learnt by men and practiced especially in the form of verbal recitation in the sacrificial

Pei-yi Guo

30

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

ERIC Educational Resources Information Center

|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…

Burton, Lindsay J.

2012-01-01

31

Geochemistry and petrogenesis of the Gallego Volcanic Field, Solomon Islands, SW Pacific and geotectonic implications  

NASA Astrophysics Data System (ADS)

The Upper Miocene to present day Gallego Volcanic Field (GVF) is located in northwest Guadalcanal, Solomon Islands, SW Pacific, and potentially includes the offshore Savo volcano. The GVF is a multi-centred complex covering an area of ~ 800 km2 on Guadalcanal and a further ~ 30 km2 on the island of Savo, north of west Guadalcanal. GVF volcanism is characterised by effusive eruptions of lava, intrusion of sub-volcanic plutons, as well as pyroclastic flow and fall deposits dominated by block and ash flow deposits. Geochemical analysis of a representative suite of samples from the GVF demonstrates that the GVF comprise largely a 'main suite' of basalts to andesites and minor trachyandesites. The predominant mineralogy of the GVF comprises plagioclase, amphibole, clinopyroxene and magnetite-ilmenite. Associated with the 'main suite' are cognate nodules composed of hornblendite, gabbros, and clinopyroxenite. Interpretation of major and trace element geochemistry and petrographic studies suggests that fractionation was dominated by early clinopyroxene, and later amphibole + clinopyroxene + minor plagioclase. Geochemical features such as the incompatibility of Sr suggest that plagioclase largely crystallised en-masse late in the fractionation sequence. The presence of amphibole and late fractionation of plagioclase is suggestive of derivation from initially water-rich magmas. The region is characterised by strong geographically-related geochemical variations as evidenced by the Woodlark (and Manus) basins: basalts become more arc-like within the ocean basins with decreasing distance to the subducting trench. The GVF-Savo volcanoes are spatially and geochemically affected by deep N-S fractures that show some evidence of sympathetic geochemical variations with distance from the trench (e.g. Sr/Y ratios). Comparison with a range of international data for Th/Nb vs Pb/Nb and Dy/Yb vs SiO2 indicate that: amphibole was indeed a strong controlling phase on magmatic evolution; garnet had no obvious role; there was little sediment input into the source region; that relative Pb/Nb enrichments may be linked to similar enrichments within the subducting Woodlark basin (and by analogy with the Manus basin and its abundant hydrothermal Pb-rich sulphide deposits); and the predominant influence on the source region for GVF-Savo was from metasomatic fluids and/or melts from the slab subducting at the southern trench.

Petterson, M. G.; Haldane, M. I.; Smith, D. J.; Billy, D.; Jordan, N. J.

2011-08-01

32

Kanaga Volcano, Aleutian Islands, Alaska  

NSDL National Science Digital Library

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

33

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

SciTech Connect

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.

Hirono, A.; Ishii, A.; Hirono, K.; Miwa, S. [National Institute of Health, Tokyo (Japan); Kere, N. [Medical Research and Training Institute, Honiara (Japan); Fujii, H. [Tokyo Women`s Medical College, Tokyo (Japan)

1995-05-01

34

The relationship between early childhood education and primary school academic achievement in Solomon Islands  

Microsoft Academic Search

This paper determines the relationship between early childhood education and primary school academic achievement in Solomon\\u000a Islands. By identifying factors within early childhood education programmes that influence children’s primary school academic\\u000a achievement, this study seeks to offer additional understanding about the relationships between early childhood and primary\\u000a education that may be utilized by educators, policy planners at all levels, and

Diana E. Guild

2000-01-01

35

Exploring provider and community responses to the new malaria diagnostic and treatment regime in Solomon Islands  

Microsoft Academic Search

BACKGROUND: Improvements in availability and accessibility of artemisinin-based combination therapy (ACT) for malaria treatment and the emergence of multi-drug-resistant parasites have prompted many countries to adopt ACT as the first-line drug. In 2009, Solomon Islands (SI) likewise implemented new national treatment guidelines for malaria. The ACT, Coartem® (artemether-lumefantrine) is now the primary pharmacotherapy in SI for Plasmodium falciparum malaria, Plasmodium

Rushika S Wijesinghe; Jo-An M Atkinson; Albino Bobogare; Lyndes Wini; Maxine Whittaker

2011-01-01

36

“We Wia Ragai”: Missionary Collection and Synergetic Assemblages in the Solomon Islands 1920–1942  

Microsoft Academic Search

An entry in Edith Safstrom’s diary, We Wia Ragai, marks her first posting to the girl’s mission school in the Solomon Islands, and is a Mota phrase told to her by lay missionary\\u000a colleague, Ida Wench. The phrase essentially means “it is good to be here among you all” and echoed Edith’s thoughts on life\\u000a at the school on tiny

Diana M. Smith

2010-01-01

37

Indigenous knowledge and the near field population response during the 2007 Solomon Islands tsunami  

Microsoft Academic Search

The magnitude 8.1 earthquake and subsequent tsunami killed 52 people when it hit the Solomon Islands on 2 April 2007. That\\u000a number would have likely been considerably higher were it not for the appropriate reaction of the indigenous coastal populations\\u000a and a helpful physical geography. Buffering coral reefs reflected some wave energy back to sea, reducing the power of the

Brian G. McAdoo; Andrew Moore; Jennifer Baumwoll

2009-01-01

38

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

PubMed

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

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

2013-01-14

39

Child health nurses in the Solomon Islands: lessons for the Pacific and other developing countries  

PubMed Central

Objectives To understand the roles of nurses with advanced training in paediatrics in the Solomon Islands, and the importance of these roles to child health. To understand how adequately equipped child health nurses feel for these roles, to identify the training needs, difficulties and future opportunities. Design Semi-structured interviews. Settings Tertiary hospital, district hospitals and health clinics in the Solomon Islands. Participants Twenty-one paediatric nurses were interviewed out of a total of 27 in the country. Results All nurses were currently employed in teaching, clinical or management areas. At least one or two nurses were working in each of 7 of the 9 provinces; in the two smaller provinces there were none. Many nurses were sole practitioners in remote locations without back-up from doctors or other experienced nurses; all had additional administrative or public health duties. Different types of courses were identified: a residential diploma through the University of Papua New Guinea or New Zealand and a diploma by correspondence through the University of Sydney. Conclusions Child health nurses in the Solomon Islands fulfill vital clinical, public health, teaching and administrative roles. Currently they are too few in number, and this is a limiting factor for improving the quality of child health services in that country. Current methods of training require overseas travel, or are expensive, or lack relevance, or remove nurses from their work-places and families for prolonged periods of time. A local post-basic child health nursing course is urgently needed, and models exist to achieve this.

2012-01-01

40

Regional offshore geology of central and western Solomon Islands and Bougainville, Papua New Guinea  

SciTech Connect

The central and western Solomon Islands and the Bougainville regions are parts of a complex island-arc system that includes an intra-arc basin and remnants of both forearc and back-arc depositional wedges. These features formed in response to episodic Cenozoic tectonism along the convergent boundary between the Pacific and Australia-India plates. Presumed early Tertiary southwest-directed subduction of the Pacific plate and associated arc magmatism were curtailed by impingement of the leading edge of the Ontong Java Plateau. Aprons of back-arc and forearc sediment were derived from highstanding parts of the arc during the late Oligocene and early Miocene. Late Tertiary arc-polarity reversal and northeastward-directed subduction of the Woodlark spreading system caused a renewal of island-arc magmatism that completed the construction of the Central Solomons Trough as an enclosed intra-arc basin. Interpretations of multichannel profiles from 1982 and 1984 CCOP/SOPAC Tripartite Cruises of the research vessel R/V S.P. Lee indicate that the Central Solomons Trough is a composite intra-arc basin containing as much as 5.5 km of late Oligocene(.) and younger sedimentary rocks. As many as five lenticular seismic-stratigraphic units can be identified on the basis of unconformities and abrupt velocity changes. Late Miocene and younger folds and faults deform the northeast and southwest flanks of the basin. Profiles across the Kilinailau Trench show Ontong Java Plateau rocks covered by 2-4 km of trench sediment. The inner trench wall consists of folded, upfaulted, and rotated blocks of trench and forearc strata. The deep-water basin northwest of Bougainville is a southeastward extension of the New Ireland forearc basin, the southern margin of which is formed by a subsided part of the early Cenozoic arc. There, Oligocene(.) and younger basin strata, as much as 7 km thick, are deformed by pre-Pliocene faults and folds.

Vedder, J.G.; Colwell, J.B.; Bruns, T.R.; Cooper, A.K.

1986-07-01

41

The petrology of the Las Canadas volcanoes, Tenerife, Canary islands  

Microsoft Academic Search

Tenerife is the largest of the seven Tertiary to Recent volcanic islands that make up the Canary Archipelago. The island is composed of volcanics belonging to the basanitetrachyte-phonolite assemblage that characterises many Atlantic islands. The most voluminous development of intermediate and salic volcanics has been in the centre of the island where the Las Canadas volcanoes arose upon a basement

William Ian Ridley

1970-01-01

42

Tsunami Field Survey for the Solomon Islands Earthquake of April 1, 2007  

NASA Astrophysics Data System (ADS)

Two weeks after the 2007 off-Solomon earthquake, an international tsunami survey team (ITST) of Japanese and US researchers performed a post tsunami survey in Ghizo and adjacent islands. Main purpose of the team was to provide information on the earthquake and tsunami to the national disaster council of the Solomon Islands, who was responsible for the disaster management at that time. The ITST had interview with the affected people and conducted reconnaissance mapping of the tsunami heights and flow directions. Tsunami flow heights at beach and inland were evaluated from watermarks on buildings and the position of broken branches and stuck materials on trees. These tsunami heights along the southern to western coasts of Ghizo Island were ca. 5m (a.s.l.). Tsunami run-up was traced by distribution of floating debris that carried up by the tsunami and deposited at their inundation limit. The maximum run-up was measured at Tapurai of Simbo Island to be ca. 9 m. Most of the inundation area was covered by 0-10 cm thick tsunami deposit that consists of beach sand, coral peaces and eroded soil. Coseismic uplift and subsidence were clearly identified by changes of the sea level before and after the earthquake, that were inferred by eyewitness accounts and evidences such as dried up coral reeves. These deformation patterns, as well as the tsunami height distribution, could constrain the earthquake fault geometry and motion. It is worthy of mention that the tsunami damage in villages in Ranongga Island has significantly reduced by 2-3 m uplift before the tsunami attack.

Nishimura, Y.; Tanioka, Y.; Nakamura, Y.; Tsuji, Y.; Namegaya, Y.; Murata, M.; Woodward, S.

2007-12-01

43

Malaria control in central Malaita, Solomon Islands 2. Local perceptions of the disease and practices for its treatment and prevention  

Microsoft Academic Search

Government health policy for malaria control in Solomon Islands has three main objectives: (1) early diagnosis and treatment of malaria at a health service; (2) reduction of human-vector contact through widespread use of insecticide-impregnated bed nets; and (3) provision of malaria chemoprophylaxis for pregnant women. Social research was carried out in thirteen villages in central Malaita to determine local attitudes

Joel M. Dulhunty; Keflemariam Yohannes; Chaibai Kourleoutov; Vaipulu T. Manuopangai; Morris K. Polyn; William J. Parks; Joan H. Bryan

2000-01-01

44

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

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

45

A survey for plant diseases caused by viruses and virus-like pathogens in the Solomon Islands  

Microsoft Academic Search

.  Surveys for virus and virus-like plant diseases were conducted on the islands of Guadalcanal, Malaita, Ndende and Temon Neo\\u000a in the Solomon Islands. New plant virus records for the country were those of Zucchini yellow mosaic virus (ZYMV) in Citrulus lanatus (watermelon), Cucurbita maxima (pumpkin), Cucumis melo (rockmelon) and Cucumis sativas (cucumber); Turnip mosaic virus (TuMV) in Brassica chinensis (Chinese

R. I. Davis; H. Tsatsia

2009-01-01

46

2007 Solomon Islands Tsunami Left Little Sand Onshore, Buried Backshore Reefs  

NASA Astrophysics Data System (ADS)

In many places struck by the 2007 Solomon Islands tsunami, little onshore record of the tsunami's passage remains yet considerable sediment was transported offshore. This sediment represents an ecological hazard in tropical regions because of its potential for burying coral reefs. At Nusa Agana, a 50 m-wide, 2 m-high barrier island ~36 km N of the epicenter, flow depths recorded by debris wrapped around tree trunks did not exceed 50 cm--the sedimentary record on land was similarly small at ~2 cm thick. Nevertheless, the "outer" coastline of the island was stripped of sediment and the "inner" coastline filled with enough sediment to bury coral reefs to an extent that only soft corals at the top of the reef survive. The source of the sediment appears to be a mixture of sand from both the outer and inner beach, suggesting that scour occurred at both these locations. Perhaps because of the island's low relief, Nusa Agana acted less as a barrier to flow and more as a topographic high; sediment cover thinned over the high and selectively infilled the topographic low of the lagoon. At Tapurai, ~55 km ENE of the epicenter, the tsunami left a layer of coral rubble 20-30 cm thick and moved basalt boulders up to 1 m in diameter more than 100 m inland. The tsunami here reached flow depths of more than 8 m and swept N-SW across fan-shaped Tapurai, piling coral rubble mixed from offshore reefs and the modern beach onto farm fields before striking a basalt cliff behind the town and deflecting SW, carrying basalt debris with it before exiting through the town's harbor. The sediment leaves a vivid account of the passage of the wave, progressing from a solely coral rubble deposit to a mixed basalt-coral deposit and thinning downflow as sediment supply waned. Where the tsunami washed completely over islands, the side facing the waves is typically stripped of sediment, whereas the lee side shows a well developed scarp, suggesting that at least some tsunami scarps are formed during backflow and not during initial tsunami attack. At Nusa Agana, no scarp was visible one month after the event on the outer coast, but a 40 cm high scarp remained visible on the inner coast. Similarly, at Tapurai no scarp was visible on the coast first struck by the tsunami, but a well-developed scarp 50 cm high remained where the tsunami flowed offshore. Although relatively small, the 2007 Solomon Islands tsunami provides an unusual test for ideas about how tsunamis affect coastlines, and demonstrates that in at least some cases most of the sediment deposition (and ecological damage) are offshore.

Moore, A. L.; Jackson, K. L.; Kruger, J.; McAdoo, B. G.; Rafiau, W. B.; Tiano, B.; Woodward, S. M.

2007-12-01

47

NEW SPECIES OF BITING MIDGES FROM THE SOLOMON ISLANDS (DIPTERA: CERATOPOGONIDAE)  

Microsoft Academic Search

Three species of biting midges from the Solomon Is are described and illustrated: Brachypogon kraussi, n. sp., B. tokunagai, n. sp., and Dasyhelea forsteri, n. sp. Another Ceratopogonid, Alluaudomyia bifasciata, originally described from New Guinea, is recorded for the first time from the Solomon Is. Previous records of Ceratopogonid ae from the Solomon Is are scanty. Macfie (1938) described Dasyhelea

William L. Grogan; Willis W. Wirth

1981-01-01

48

Chronic suppurative otitis media in the Solomon Islands: a prospective, microbiological, audiometric and therapeutic survey.  

PubMed

Chronic suppurative otitis media affected 3.8% of 3500 Solomon Island children under 15 years (and 6.1% under 5 years) and was the sole cause of conductive hearing loss recorded in 265 children tested audiometrically. It was characterised by early onset (65% under 18 months) male preponderance and large central tubotympanic perforations. Measles, respiratory infections, swimming and malnutrition were identified as aetiological factors amenable to intervention. Proteus and pseudomonas were the principle aerobes isolated from ear pus and gentamicin the only antibiotic tested to be effective against them. However although a prospective therapeutic trial demonstrated a significantly improved outcome after aural toilet, no additional benefit was imparted by concurrent ototopical boric acid or aminoglycoside solution or oral antianaerobic clindamycin. Parental tuition in aural cleaning, avoidance of ear water entry, nose blowing and breathing will yield a good result in up to 60% of children in half of whom tympanic healing occurred. PMID:3466089

Eason, R J; Harding, E; Nicholson, R; Nicholson, D; Pada, J; Gathercole, J

1986-10-22

49

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

NASA Astrophysics Data System (ADS)

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.

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

2008-03-01

50

Marine protected areas and resilience to sedimentation in the Solomon Islands  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

51

Coseismic and Postseismic slip distribution of the 2007 Solomon Islands Earthquake deduced from A Bayesian Inversion  

NASA Astrophysics Data System (ADS)

In inversion of geodetic data for distribution of fault slip minimizing the first or second order derivatives of slip across fault plane is generally employed to smooth slips of neighboring patches.Smoothing parameter is subjective selected to determine the relative weight placed on fitting data versus smoothing the slip distribution.We use the Fully Bayesian Inversion method(Fukuda,2008)to simultaneously estimate the slip distribution and smoothing parameter objectively in a Bayesian framework. The distributed slips,the posterior probability density function and the smoothing parameter is formulated with Bayes' theorem and sampled with a Markov chain Monte Carlo method. Here We will apply this method to Coseismic and Postseismic displacement data from the 2007 Solomon Islands Earthquake and compare the results of this method with generally favored method.

Chen, T.; Gong, X.

2011-12-01

52

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

NASA Astrophysics Data System (ADS)

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 (70Solomon Islands. These px-rich rocks may have been exhumed by backthrusting of arc portions during the the collision of the OJP (Petterson et al, 1998) or/and carried by buoyant serpentinites (Hermann et al, 2000).

Berly, T.

2001-12-01

53

2003 Eruption of Chikurachki Volcano, Paramushir Island, Northern Kuriles, Russia  

Microsoft Academic Search

Chikurachki Volcano in the northern Kurile Islands erupted for the second time in two years in mid-April 2003. Although the Kamchatka Volcanic Eruptions Response Team (KVERT) received word of a possible eruption from residents of Paramushir Island on April 17, poor weather precluded confirmation of volcanic activity, and the exact start date is uncertain. On April 18, during routine satellite

D. J. Schneider; O. A. Girina; C. A. Neal; L. Kotenko; N. S. Terentiev; P. Izbekov; I. Belousov; S. Senyukov; A. A. Ovsyannikov

2003-01-01

54

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

SciTech Connect

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.

Bruns, T.R.; Vedder, J.G. (Geological Survey, Menlo Park, CA (USA))

1990-06-01

55

Community perceptions of mental health needs: a qualitative study in the Solomon Islands  

PubMed Central

Background Psychosocial and mental health needs in the aftermath of conflict and disaster have attracted substantial attention. In the Solomon Islands, the conceptualisation of mental health, for several decades regarded by policy makers as primarily a health issue, has broadened and been incorporated into the national development and social policy agendas, reflecting recognition of the impact of conflict and rapid social change on the psychosocial wellbeing of the community as a whole. We sought to understand how mental health and psychosocial wellbeing were seen at the community level, the extent to which these issues were identified as being associated with periods of 'tension', violence and instability, and the availability of traditional approaches and Ministry of Health services to address these problems. Methods This article reports the findings of qualitative research conducted in a rural district on the island of Guadalcanal in the Solomon Islands. Key informant interviews were conducted with community leaders, and focus groups were held with women, men and young people. Wellbeing was defined broadly. Results Problems of common concern included excessive alcohol and marijuana use, interpersonal violence and abuse, teenage pregnancy, and lack of respect and cooperation. Troubled individuals and their families sought help for mental problems from various sources including chiefs, church leaders and traditional healers and, less often, trauma support workers, health clinic staff and police. Substance-related problems presented special challenges, as there were no traditional solutions at the individual or community level. Severe mental illness was also a challenge, with few aware that a community mental health service existed. Contrary to our expectations, conflict-related trauma was not identified as a major problem by the community who were more concerned about the economic and social sequelae of the conflict. Conclusion Communities identify and are responding to a wide range of mental health challenges; the health system generally can do more to learn about how this is being done, and build more comprehensive services and policy on this foundation. The findings underscore the need to promote awareness of those services which are available, to extend mental health care beyond urban centres to rural villages where the majority of the population live, and to promote community input to policy so as to ensure that it 'fits' the context.

Blignault, Ilse; Bunde-Birouste, Anne; Ritchie, Jan; Silove, Derrick; Zwi, Anthony B

2009-01-01

56

Living on Active Volcanoes - The Island of Hawaii  

NSDL National Science Digital Library

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

Heliker, Christina; Stauffer, Peter; Hendley Ii., James

57

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

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…

Sperry, Robert

58

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

|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…

Sperry, Robert

59

Exploring provider and community responses to the new malaria diagnostic and treatment regime in Solomon Islands  

PubMed Central

Background Improvements in availability and accessibility of artemisinin-based combination therapy (ACT) for malaria treatment and the emergence of multi-drug-resistant parasites have prompted many countries to adopt ACT as the first-line drug. In 2009, Solomon Islands (SI) likewise implemented new national treatment guidelines for malaria. The ACT, Coartem® (artemether-lumefantrine) is now the primary pharmacotherapy in SI for Plasmodium falciparum malaria, Plasmodium vivax malaria or mixed infections. Targeted treatment is also recommended in the new treatment regime through maintenance of quality microscopy services and the introduction of Rapid Diagnostic Tests (RDTs). Ascertaining the factors that influence community and provider acceptance of and adherence to the new treatment regime will be vital to improving the effectiveness of this intervention and reducing the risk of development of drug resistance. Methods In order to understand community and prescriber perceptions and acceptability of the new diagnostic and treatment interventions, 12 focus group discussions (FGDs) and 12 key informant interviews (KII) were carried out in rural and urban villages of Malaita Province, Solomon Islands four months subsequent to roll out of these interventions. Results Lack of access to microscopy or distrust in the accuracy of diagnostic tools were reported by some participants as reasons for the ongoing practice of presumptive treatment of malaria. Lack of confidence in RDT accuracy has negatively impacted its acceptability. Coartem® had good acceptability among most participants, however, some rural participants questioned its effectiveness due to lack of side effects and the larger quantity of tablets required to be taken. Storing of left over medication for subsequent fever episodes was reported as common. Conclusion To address these issues, further training and supportive supervision of healthcare workers will be essential, as will the engagement of influential community members in health promotion activities to improve acceptability of RDTs and adherence to the new treatment regime. Exploring the extent of these issues beyond the study population must be a priority for malaria programme managers. Practices such as presumptive treatment and the taking of sub-curative doses are of considerable concern for both the health of individuals and the increased risk it poses to the development of parasite resistance to this important first-line treatment against malaria.

2011-01-01

60

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

PubMed

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 consumers in developing countries become more aware, they will continue to be exploited by developed countries. PMID:12265890

Joseph, F G

1981-01-01

61

Microearthquake seismicity in relation to double convergence around the Solomon Islands arc by ocean-bottom seismometer observation  

NASA Astrophysics Data System (ADS)

The Solomon Islands arc area is a complex plate convergence zone. At the North Solomon Trench on the northern side of the arc, it is believed that the Pacific Plate was subducting before coming into collision with the Ontong Java Plateau, the world's largest oceanic plateau. After the collision about 5 Ma, northeastward subduction initiated along the southern side of the arc at the San Cristobal Trench, another trench on the south side. GPS observations and crustal seismic structure surveys confirm that convergence occurs at both trenches. Without detailed and accurate seismicity, it is difficult to characterize the plate subduction to reveal the tectonics of such a complex zone where a key mechanism of continental growth may also exist. In 1994, an ocean-bottom seismometer (OBS) experiment was carried out for the first time in the area around the Solomon Islands arc to locate microearthquakes. Observations started in late August and continued until early September. Five digital recording OBSs were deployed around the Russell Islands west of Guadalcanal Island. OBS spacing was about 20 km. All the OBSs were recovered and yielded data with a good signal-to-noise ratio. 40 earthquakes, with magnitudes in the range 1.5-4.4 were located over 8 days. The seismicity clearly images the two subducting plates. Though the seismicity beneath the arc side slope of the San Cristobal Trench is relatively high, we can see the seismicity which is related to the subducting Pacific Plate beneath Santa Isabel Island. In addition, earthquakes occur within the crust beneath the southern part of the New Georgia Basin and the Russell Islands. An aseismic area extending 40 km inward from the San Cristobal trench axis implies initial aseismic slip of the India-Australia Plate at a small dip angle.

Shinohara, Masanao; Suyehiro, Kiyoshi; Murayama, Takayuki

2003-06-01

62

The active volcanoes of Kamchatka and Paramushir Island, North Kurils in 2007  

Microsoft Academic Search

Eight strong eruptions of four Kamchatka volcanoes (Bezymyannyi, Klyuchevskoi, Shiveluch, and Karymskii) and Chikurachki Volcano\\u000a on Paramushir Island, North Kurils took place in 2007. In addition, an explosive event occurred on Mutnovskii Volcano and\\u000a increased fumarole activity was recorded on Avacha and Gorelyi volcanoes in Kamchatka and Ebeko Volcano on Paramushir Island,\\u000a North Kurils. Thanks to close cooperation with colleagues

O. A. Girina; S. V. Ushakov; N. A. Malik; A. G. Manevich; D. V. Mel’nikov; A. A. Nuzhdaev; Yu. V. Demyanchuk; L. V. Kotenko

2009-01-01

63

Depths of Magma Storage Beneath Fogo Volcano, Cape Verde Islands  

Microsoft Academic Search

Fogo is one of the most active oceanic volcanoes of the world in present time and the only island of the Cape Verde archipelago with historic volcanic activity. We have carried out a barometric study of basanitic to tephriphonolitic volcanic rocks of the 1995 eruption of Fogo in order to reconstruct the depths of magma reservoirs and magma pathways prior

E. Hildner; A. Klügel

2008-01-01

64

The Subsistence Fishery Productivity and Marine Resource Knowledge of Resettled Polynesians from Tikopia Island, Solomon Islands  

Microsoft Academic Search

This study documents the fishing practices and local knowl- edge of marine resources of a group of Polynesian Tikopians who were resettled to Nukufero Village in the Russell Islands in the 1950s. Both the exploitation of the marine resources and cultural attitudes associated with the resource utilization in their new location are described. Technological advances like the use of monofilament

NORMAN QUINN; MELCHIOR MATAKI

65

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

Microsoft Academic Search

The Cumbre Vieja volcano is the youngest component of the island of La Palma. It is a very steep-sided oceanic island volcano, of a type which may undergo large-scale lateral collapse with little precursory deformation. Reconfiguration of the volcanic rift zones and underlying dyke swarms of the volcano is used to determine the present degree of instability of the volcano.

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

1999-01-01

66

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

Microsoft Academic Search

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

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

2003-01-01

67

Electromagnetic Imaging and Seismotectonics of Mud Volcanoes in Andaman Islands  

NASA Astrophysics Data System (ADS)

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

Subba Rao, Pbv; Singh, Ak

2012-07-01

68

Operational research to inform a sub-national surveillance intervention for malaria elimination in Solomon Islands  

PubMed Central

Background Successful reduction of malaria transmission to very low levels has made Isabel Province, Solomon Islands, a target for early elimination by 2014. High malaria transmission in neighbouring provinces and the potential for local asymptomatic infections to cause malaria resurgence highlights the need for sub-national tailoring of surveillance interventions. This study contributes to a situational analysis of malaria in Isabel Province to inform an appropriate surveillance intervention. Methods A mixed method study was carried out in Isabel Province in late 2009 and early 2010. The quantitative component was a population-based prevalence survey of 8,554 people from 129 villages, which were selected using a spatially stratified sampling approach to achieve uniform geographical coverage of populated areas. Diagnosis was initially based on Giemsa-stained blood slides followed by molecular analysis using polymerase chain reaction (PCR). Local perceptions and practices related to management of fever and treatment-seeking that would impact a surveillance intervention were also explored using qualitative research methods. Results Approximately 33% (8,554/26,221) of the population of Isabel Province participated in the survey. Only one subject was found to be infected with Plasmodium falciparum (Pf) (96 parasites/?L) using Giemsa-stained blood films, giving a prevalence of 0.01%. PCR analysis detected a further 13 cases, giving an estimated malaria prevalence of 0.51%. There was a wide geographical distribution of infected subjects. None reported having travelled outside Isabel Province in the previous three months suggesting low-level indigenous malaria transmission. The qualitative findings provide warning signs that the current community vigilance approach to surveillance will not be sufficient to achieve elimination. In addition, fever severity is being used by individuals as an indicator for malaria and a trigger for timely treatment-seeking and case reporting. In light of the finding of a low prevalence of parasitaemia, the current surveillance system may not be able to detect and prevent malaria resurgence. Conclusion An adaption to the malERA surveillance framework is proposed and recommendations made for a tailored provincial-level surveillance intervention, which will be essential to achieve elimination, and to maintain this status while the rest of the country catches up.

2012-01-01

69

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

70

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

NASA Astrophysics Data System (ADS)

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

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

71

Genetic diversity in two sibling species of the Anopheles punctulatus group of mosquitoes on Guadalcanal in the Solomon Islands  

PubMed Central

Background The mosquito Anopheles irenicus, a member of the Anopheles punctulatus group, is geographically restricted to Guadalcanal in the Solomon Islands. It shows remarkable morphological similarities to one of its sibling species, An. farauti sensu stricto (An. farauti s.s.), but is dissimilar in host and habitat preferences. To infer the genetic variations between these two species, we have analyzed mitochondrial cytochrome oxidase subunit II (COII) and nuclear ribosomal internal transcribed spacer 2 (ITS2) sequences from Guadalcanal and from one of its nearest neighbours, Malaita, in the Solomon Islands. Results An. farauti s.s. was collected mostly from brackish water and by the human bait method on both islands, whereas An. irenicus was only collected from fresh water bodies on Guadalcanal Island. An. irenicus is distributed evenly with An. farauti s.s. (?SC = 0.033, 0.38%) and its range overlaps in three of the seven sampling sites. However, there is a significant population genetic structure between the species (?CT = 0.863, P < 0.01; ?ST = 0.865, P < 0.01 and FST = 0.878, P < 0.01). Phylogenetic analyses suggest that An. irenicus is a monophyletic species, not a hybrid, and is closely related to the An. farauti s.s. on Guadalcanal. The time estimator suggests that An. irenicus diverged from the ancestral An. farauti s.s. on Guadalcanal within 29,000 years before present (BP). An. farauti s.s. expanded much earlier on Malaita (texp = 24,600 BP) than the populations on Guadalcanal (texp = 16,800 BP for An. farauti s.s. and 14,000 BP for An. irenicus). Conclusion These findings suggest that An. irenicus and An. farauti s.s. are monophyletic sister species living in sympatry, and their populations on Guadalcanal have recently expanded. Consequently, the findings further suggest that An. irenicus diverged from the ancestral An. farauti s.s. on Guadalcanal.

2008-01-01

72

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

PubMed Central

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

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

1991-01-01

73

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

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…

Fillion, Jacob; Weeks, Julius

74

Growth and collapse of the Reunion Island volcanoes  

NASA Astrophysics Data System (ADS)

This work presents the first exhaustive study of the entire surface of the Reunion Island volcanic system. The focus is on the submarine part, for which a compilation of all multibeam data collected during the last 20 years has been made. Different types of submarine features have been identified: a coastal shelf, debris avalanches and sedimentary deposits, erosion canyons, volcanic constructions near the coast, and seamounts offshore. Criteria have been defined to differentiate the types of surfaces and to establish their relative chronology where possible. Debris avalanche deposits are by far the most extensive and voluminous formations in the submarine domain. They have built four huge Submarine Bulges to the east, north, west, and south of the island. They form fans 20-30 km wide at the coastline and 100-150 km wide at their ends, 70-80 km offshore. They were built gradually by the superimposition and/or juxtaposition of products moved during landslide episodes, involving up to several hundred cubic kilometers of material. About 50 individual events deposits can be recognized at the surface. The landslides have recurrently dismantled Piton des Neiges, Les Alizés, and Piton de La Fournaise volcanoes since 2 Ma. About one third are interpreted as secondary landslides, affecting previously emplaced debris avalanche deposits. On land, landslide deposits are observed in the extensively eroded central area of Piton des Neiges and in its coastal areas. Analysis of the present-day topography and of geology allows us to identify presumed faults and scars of previous large landslides. The Submarine Bulges are dissected and bound by canyons up to 200 m deep and 40 km long, filled with coarse-grained sediments, and generally connected to streams onshore. A large zone of sedimentary accumulation exists to the north-east of the island. It covers a zone 20 km in width, extending up to 15 km offshore. Volcanic constructions are observed near the coast on both Piton des Neiges and Piton de la Fournaise volcanoes and are continuations of subaerial structures. Individual seamounts are present on the submarine flanks and the surrounding ocean floor. A few seem to be young volcanoes, but the majority are probably old, eroded seamounts. This study suggests a larger scale and frequency of mass-wasting events on Reunion Island compared to similar islands. The virtual absence of downward flexure of the lithosphere beneath the island probably contributes to this feature. The increased number of known flank-failure events has to be taken into consideration when assessing hazards from future landslides, in particular, the probability of landslide-generated tsunamis.

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

2008-04-01

75

Ritter Island Volcano-lateral collapse and the tsunami of 1888  

Microsoft Academic Search

In the early morning of 1888 March 13, roughly 5 km3 of Ritter Island Volcano fell violently into the sea northeast of New Guinea. This event, the largest lateral collapse of an island volcano to be recorded in historical time, flung devastating tsunami tens of metres high on to adjacent shores. Several hundred kilometres away, observers on New Guinea chronicled

Steven N. Ward; Simon Day

2003-01-01

76

2003 Eruption of Chikurachki Volcano, Paramushir Island, Northern Kuriles, Russia  

NASA Astrophysics Data System (ADS)

Chikurachki Volcano in the northern Kurile Islands erupted for the second time in two years in mid-April 2003. Although the Kamchatka Volcanic Eruptions Response Team (KVERT) received word of a possible eruption from residents of Paramushir Island on April 17, poor weather precluded confirmation of volcanic activity, and the exact start date is uncertain. On April 18, during routine satellite image analysis, the Alaska Volcano Observatory (AVO) detected an ash cloud from Chikurachki in GMS data and immediately notified the Federal Aviation Administration (FAA), National Weather Service, and other agencies. Subsequent formal alerts were issued through aviation and meteorological channels as outlined in the Alaska Interagency Operating Plan for Volcanic Ash Episodes. Thermal infrared imagery and trajectory models suggested the initial cloud was relatively low-level (below 25,000 ft ASL), however this height was not well constrained. Over the next several months, activity at Chikurachki consisted largely of strombolian bursts producing intermittent ash clouds reaching heights of generally less than 10-13,000 ft. ASL. Ash fall was noted as far as 60 km downwind. The last confirmed eruptive activity was June 16, 2003. During the eruption, AVHRR, MODIS, and GMS satellites captured images of the ash cloud as far as 300 km generally east and southeast of the volcano in the region heavily traveled North Pacific air routes. The propagation of volcanic clouds was monitored using visual and infrared channels and included a routine split-window analysis. Weak thermal anomalies were detected in AVHRR images suggesting minimal effusive activity near the central vent. Over the course of the eruption, aviation and meteorological authorities in Russia, the U.S., and Japan issued official notices regarding the eruption and the position and estimated height of the ash plume. Impacts to aviation were minor due to the low-level and intermittent nature of the eruption. Chikurachki is a young, basaltic 1816-m-tall stratovolcano on the northern coast of Paramushir Island, 370 km southwest of Petropavlovsk-Kamchatsky. No seismic or other instrumentation exists near the volcano, however satellite imagery is examined at least twice daily to look for evidence of volcanic unrest. The nearest community is Severo-Kurilsk (population ~3,000), 60 km to the northeast. Previous historical eruptions have primarily consisted of VEI 1-2 strombolian eruptions, however, plinian eruptions with significant local fall deposits were recorded in 1986 and 1853. Its most recent eruption from January 25 - March 16, 2002 was similar in character to the 2003 event.

Schneider, D. J.; Girina, O. A.; Neal, C. A.; Kotenko, L.; Terentiev, N. S.; Izbekov, P.; Belousov, I.; Senyukov, S.; Ovsyannikov, A. A.

2003-12-01

77

Ocean noise triggering of LP events at Deception Island volcano  

NASA Astrophysics Data System (ADS)

During the austral winter 2009, swarms of long-period (LP) events with astonishingly regular interevent times were recorded at Deception Island volcano, Antarctica. Swarm events have similar waveforms, indicating the repeated activation of a non-destructive source process. These swarms may last up to a few hours, and characteristic inter-event times range from ~10 s to ~20 s for individual swarms. The amplitudes of the periodic LPs vary significantly over a short time scale, which makes an association with a steady state internal process complicate. On the other hand, we observe that LP inter-event times are approximate integer multiples of the dominant periods of the oceanic microseism, and propose that the periodicity observed in the occurrence times of LP events is the result of dynamic triggering of the LP source process by the effect of oceanic microtremors. A positive correlation between microseism amplitude and LP periodicity supports this idea. We attribute LP periodicity to the coincidence of sustained LP activity in an unstable hydrothermal system and external forcing by ocean noise that introduces periodic pressure variations in volcano fluids. We estimate the volumetric strain change generated by the oceanic microseism at the source location and conclude that strain of order 10-7 is sufficient to introduce clear periodicity in the LP sequences.

Stich, D.; Almendros, J.; Jiménez, V.; Mancilla, F.; Carmona, E.

2012-04-01

78

Remote sensing for active volcano monitoring in Barren Island, India  

SciTech Connect

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

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

1993-08-01

79

Highly Divergent Molecular Variants of Human T-Lymphotropic Virus Type I from Isolated Populations in Papua New Guinea and the Solomon Islands  

Microsoft Academic Search

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

Antoine Gessain; Richard Yanagihara; Genoveffa Franchini; Ralph M. Garruto; Carol L. Jenkins; Andrew B. Ajdukiewicz; Robert C. Gallo; D. Carleton Gajdusek

1991-01-01

80

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

Microsoft Academic Search

Spatio-temporal variations in geodetic signals at active volcanoes provide important insight on governing subsurface processes. This contribution explores the phenomenology of volcanic unrest and eruptive activity from the perspective of both ground deformation and gravimetric investigations at an ocean island volcanic complex (Tenerife, Canary Islands) and an active andesitic arc volcano (Soufrière Hills volcano [SHV], Montserrat). Despite their marked differences

J. Gottsmann

2009-01-01

81

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

PubMed Central

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

2011-01-01

82

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

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.

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

2013-01-01

83

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

SciTech Connect

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

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

1982-10-01

84

Diffuse emission of carbon dioxide, methane, and helium-3 from Teide volcano, Tenerife, Canary Islands  

Microsoft Academic Search

Diffuse emission of CO2, CH4 and 3He was investigated in the summit crater of Teide volcano, Tenerife, Canary Islands. The results indicate that Teide volcano releases abundant CO2 not only from its active crater, but also from its flanks as diffuse soil emanations. The spatial distribution of these emanations correlates quite closely with that of geothermal anomalies and manifestations. Our

Pedro A. Hernández; Nemesio M. Pérez; José M. Salazar; Shun'ichi Nakai; Kenji Notsu; Hiroshi Wakita

1998-01-01

85

Diffuse emission of carbon dioxide, methane, and helium-3 from Teide Volcano, Tenerife, Canary Islands  

Microsoft Academic Search

Diffuse emission of CO2, CH4 and ³He was investigated in the summit crater of Teide volcano, Tenerife, Canary Islands. The results indicate that Teide volcano releases abundant CO2 not only from its active crater, but also from its flanks as diffuse soil emanations. The spatial distribution of these emanations correlates quite closely with that of geothermal anomalies and manifestations. Our

Pedro A. Hernfindez; Nemesio M. Pérez; José M. Salazar; Shun'ichi Nakai; Kenji Notsu; Hiroshi Wakita

1998-01-01

86

Elucidating the trophodynamics of four coral reef fishes of the Solomon Islands using ?15N and ?13C  

NASA Astrophysics Data System (ADS)

Size-related diet shifts are important characteristics of fish trophodynamics. Here, body size-related changes in muscle ?15N and ?13C of four coral reef fishes, Acanthurus nigrofuscus (herbivore), Chaetodon lunulatus (corallivore) , Chromis xanthura (planktivore) and Plectropomus leopardus (piscivore) were investigated at two locations in the Solomon Islands. All four species occupied distinct isotopic niches and the concurrent ?13C' values of C. xanthura and P. leopardus suggested a common planktonic production source. Size-related shifts in ?15N, and thus trophic level, were observed in C. xanthura, C. lunulatus and P. leopardus, and these trends varied between location, indicating spatial differences in trophic ecology. A literature review of tropical fishes revealed that positive ?15N-size trends are common while negative ?15N-size trends are rare. Size-?15N trends fall into approximately equal groups representing size-based feeding within a food chain, and that associated with a basal resource shift and occurs in conjunction with changes in production source, indicated by ?13C. The review also revealed large scale differences in isotope-size trends and this, combined with small scale location differences noted earlier, highlights a high degree of plasticity in the reef fishes studied. This suggests that trophic size analysis of reef fishes would provide a productive avenue to identify species potentially vulnerable to reef impacts as a result of constrained trophic behaviour.

Greenwood, N. D. W.; Sweeting, C. J.; Polunin, N. V. C.

2010-09-01

87

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

USGS Publications Warehouse

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 third of the sedimentary column. The high Th/La in Anatahan magmas is consistent with shallow loss of the top 50 m of the sedimentary column during subduction. ?? 2005 Elsevier B.V. All rights reserved.

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, D. R.

2005-01-01

88

Multistage mixing in subduction zones: Application to Merapi volcano (Java island, Sunda arc)  

Microsoft Academic Search

Many studies have argued for the contribution of at least three components, namely the mantle wedge, the subducted oceanic crust, and its sediment cover, to describe the geochemistry of island arc volcanics. However, isotope correlations reflecting a simple binary mixing can be observed at the scale of a single arc island or volcano. Here we investigate the possibility that these

Vinciane Debaille; Régis Doucelance; Dominique Weis; Pierre Schiano

2006-01-01

89

Surface Pressure Gradient and Carbon Dioxide Degassing Survey at Cumbre Vieja Volcano, La Palma, Canary Islands  

Microsoft Academic Search

La Palma (730 Km2) is one of the youngest island of the Canarian archipelago. Recent volcanic activity is concentrated on the southern part of the island, where Cumbre Vieja volcano (220 Km2) has been constructed during the last 1 Ma reaching an elevation of 1,898 m above sea level. Six historical eruptions had occurred at Cumbre Vieja, and the most

A. Alfaya; F. López; E. Padron; P. A. Hernández; J. M. Salazar; N. M. Pérez

2002-01-01

90

ASTER observations of thermal anomalies preceding the April 2003 eruption of Chikurachki volcano, Kurile Islands, Russia  

Microsoft Academic Search

Chikurachki volcano (Northern Kurile Islands Chain, Paramushir Island 50° 20?N, 155° 27?E; elevation 1816 m, stratovolcano) has been in a state of unrest for over twenty years. Its most recent eruption that began in April 2003 was preceded by an eruption between January and May 2002. Thermal infrared images from the Japanese–United States' Advanced Spaceborne Thermal Emission and Reflection radiometer

David Pieri; Michael Abrams

2005-01-01

91

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

92

Seismic Observations of Westdahl volcano and Western Unimak Island Alaska: 1999-2005  

NASA Astrophysics Data System (ADS)

Westdahl volcano is a large basaltic shield volcano on the western end of Unimak Island Alaska in the Aleutian Island Arc. The volcano is topped by three separate vents, Pogromni Volcano, Faris Peak, and Westdahl Peak. The volcano is frequently active with known eruptions from Westdahl Peak in 1964, 1978, and 1991-92 that produced large basaltic lava flows. InSAR measurements indicate that Westdahl Volcano has been inflating at a slowly declining rate since 1992 (Lu et al., 2003). The Alaska Volcano Observatory has operated a network of six short-period seismometers on Westdahl Peak since 1998. Complementing this network are similar networks centered on Shishaldin and Akutan Volcanoes. Since 1999 more than 300 earthquakes have been located within 20 km of Westdahl Volcano. A volcano specific velocity model was determined for the western half of Uminak Island by simultaneously inverting for the velocity model and hypocentral earthquake locations using the program VELEST. Earthquakes located with the new model reveal five clusters of hypocenters: (a) a shallow cluster beneath Westdahl Peak, that largely occurred during a 24-hour period on January 7, 2004, (b) a concentration of 68 earthquakes with hypocenters ranging in depth from zero to eight km beneath Faris Peak occurring continually since 1999, (c) a diffuse cluster of long-period events northwest of Westdahl and Faris Peaks, (d) a cluster of 12 earthquakes near Pinnacle Rock, 12 km southwest of Westdahl Peak in October 2003, and (e) a cluster of 43 hypocenters near Unimak Bight, 20 km east of Westdahl Peak, that occurred between January and April 2004. Focal mechanisms were derived for four earthquakes in the Faris Peak cluster and four additional earthquakes that locate off the volcanic edifice (the four mechanisms are in the Pinnacle Rock cluster, the Unimak Bight cluster, and 20 km southeast and 30 km northeast of the volcano). Focal mechanisms in the Faris Peak cluster showed normal faulting with nodal planes trending north-south to northwest-southeast. Mechanisms of the off-volcano earthquakes are generally characterized by normal faulting with nodal planes trending southwest-northeast. These events are consistent with a stress field dominated by the Aleutian subduction zone. The Faris Peak mechanisms are not consistent with the presumed regional stress field and may reflect volcanic process. Lu et al., (2003) proposed the observed inflation of Westdahl Volcano resulted from a slowly pressurizing magma source at 6 km depth beneath Westdahl Peak. The observed seismicity is consistent with this model. Lu, Z., T. Masterlark, D. Dzurisin, and R. Rykhus, 2003, Magma supply dynamics at Westdahl volcano, Alaska, modeled from satellite radar interferometry, Alaska, J. Geophys. Res. 108, 2354, doi:10.1029/2002JB002311, 2003.

Dixon, J. P.; Power, J. A.; Stihler, S. D.

2005-12-01

93

Ice record of a large eruption of Deception Island Volcano (Antarctica) in the XVIITH century  

Microsoft Academic Search

A well-marked volcanic ash layer was found at 145.9 m depth in a 154.3 m ice core recovered in 1981 on James Ross Island, Antarctic Peninsula. Ash composition analysis indicates that we are dealing with an eruption of the Deception Island volcano located some 200 km northwestward from James Ross Island. Regional lake sediments seem also to have recorded the

Alberto J. Aristarain; Robert J. Delmas

1998-01-01

94

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

Microsoft Academic Search

Investigations of air and space images of volcanoes of the Kurile arc, supplemented by observations from a vessel as well as by on-land field work on several islands, have allowed us to identify 23 active volcanoes with well-preserved horseshoe-shaped scars formed by large-scale edifice failures. Breaches of most of the scars (14 cases) range from 0.5 to 2 km wide,

A. Belousov; M. Belousova

2007-01-01

95

ERS SAR interferometry of an erupting volcano on a tropical island: Soufriere Hills volcano, Montserrat  

Microsoft Academic Search

SAR interferometry can, potentially, supply two types of useful information relevant to the 1995-99 eruption of Soufriere Hills Volcano, Montserrat: (i) the topography of the growing lava dome and its apron of pyroclastic flows, and (ii) the surface deformation of the volcano due to magma movement within. Phase information from ERS SAR data collected from July 1997 to November 1998

G. Wadge; B. Scheuchl; N. F. Stevens; D. A. Rothery; S. Blake; M. D. Palmer; C. Riley; A. Smith

1999-01-01

96

Ritter Island Volcano-lateral collapse and the tsunami of 1888  

NASA Astrophysics Data System (ADS)

In the early morning of 1888 March 13, roughly 5 km3 of Ritter Island Volcano fell violently into the sea northeast of New Guinea. This event, the largest lateral collapse of an island volcano to be recorded in historical time, flung devastating tsunami tens of metres high on to adjacent shores. Several hundred kilometres away, observers on New Guinea chronicled 3 min period waves up to 8 m high, that lasted for as long as 3 h. These accounts represent the best available first-hand information on tsunami generated by a major volcano lateral collapse. In this article, we simulate the Ritter Island landslide as constrained by a 1985 sonar survey of its debris field and compare predicted tsunami with historical observations. The best agreement occurs for landslides travelling at 40 m s-1, but velocities up to 80 m s-1 cannot be excluded. The Ritter Island debris dropped little more than 800 m vertically and moved slowly compared with landslides that descend into deeper water. Basal friction block models predict that slides with shorter falls should attain lower peak velocities and that 40+ m s-1 is perfectly compatible with the geometry and runout extent of the Ritter Island landslide. The consensus between theory and observation for the Ritter Island waves increases our confidence in the existence of mega-tsunami produced by oceanic volcano collapses two to three orders of magnitude larger in scale.

Ward, Steven N.; Day, Simon

2003-09-01

97

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

Microsoft Academic Search

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

J. c. Carracedo

1994-01-01

98

Monitoring of malaria parasite resistance to chloroquine and sulphadoxine-pyrimethamine in the Solomon Islands by DNA microarray technology  

PubMed Central

Background Little information is available on resistance to anti-malarial drugs in the Solomon Islands (SI). The analysis of single nucleotide polymorphisms (SNPs) in drug resistance associated parasite genes is a potential alternative to classical time- and resource-consuming in vivo studies to monitor drug resistance. Mutations in pfmdr1 and pfcrt were shown to indicate chloroquine (CQ) resistance, mutations in pfdhfr and pfdhps indicate sulphadoxine-pyrimethamine (SP) resistance, and mutations in pfATPase6 indicate resistance to artemisinin derivatives. Methods The relationship between the rate of treatment failure among 25 symptomatic Plasmodium falciparum-infected patients presenting at the clinic and the pattern of resistance-associated SNPs in P. falciparum infecting 76 asymptomatic individuals from the surrounding population was investigated. The study was conducted in the SI in 2004. Patients presenting at a local clinic with microscopically confirmed P. falciparum malaria were recruited and treated with CQ+SP. Rates of treatment failure were estimated during a 28-day follow-up period. In parallel, a DNA microarray technology was used to analyse mutations associated with CQ, SP, and artemisinin derivative resistance among samples from the asymptomatic community. Mutation and haplotype frequencies were determined, as well as the multiplicity of infection. Results The in vivo study showed an efficacy of 88% for CQ+SP to treat P. falciparum infections. DNA microarray analyses indicated a low diversity in the parasite population with one major haplotype present in 98.7% of the cases. It was composed of fixed mutations at position 86 in pfmdr1, positions 72, 75, 76, 220, 326 and 356 in pfcrt, and positions 59 and 108 in pfdhfr. No mutation was observed in pfdhps or in pfATPase6. The mean multiplicity of infection was 1.39. Conclusion This work provides the first insight into drug resistance markers of P. falciparum in the SI. The obtained results indicated the presence of a very homogenous P. falciparum population circulating in the community. Although CQ+SP could still clear most infections, seven fixed mutations associated with CQ resistance and two fixed mutations related to SP resistance were observed. Whether the absence of mutations in pfATPase6 indicates the efficacy of artemisinin derivatives remains to be proven.

2010-01-01

99

Volcanoes  

ERIC Educational Resources Information Center

|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)|

Kunar, L. N. S.

1975-01-01

100

Volcanoes.  

ERIC Educational Resources Information Center

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…

Tilling, Robert I.

101

Volcanoes.  

ERIC Educational Resources Information Center

|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…

Tilling, Robert I.

102

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

Microsoft Academic Search

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

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

2005-01-01

103

Shallow flank deformation at Cumbre Vieja volcano (Canary Islands): Implications on the stability of steep-sided volcano flanks at oceanic islands  

NASA Astrophysics Data System (ADS)

Volcano flank instability has been recognized at many volcanoes around the globe. Structural, morphological, geodetic and geophysical evidence supports the continuous deformation of their flanks. While identification of instability has been recognized in well-documented examples, until recently the initial stages of such processes have been difficult to capture. Using a combination of geological, geodetic and geophysical data analysis, we study the stability of the Cumbre Vieja. New descending radar interferometric data, covering a volcanologically quiet period between 1992 and 2008 at Cumbre Vieja, indicate movement away from the satellite on the western volcano flank. Using an inversion of stacked velocity maps, we determine the geometry and slip for a near-horizontal dislocation beneath the western flank of Cumbre Vieja. Our ground deformation modelling results (position and depth) are in agreement with a low-density anomaly constrained by gravity data. The previously undetected intereruptive ground deformation at Cumbre Vieja volcano flanks was explained as an indicator of a kinematic passive response model of the flank, where the flanks were mobilized only during periods of magmatic activity (shallow dike intrusions) and remained stable and undeformed during intereruptive periods. Here, we present new results indicating that active creeping stress release due to gravitational loading is also a dominant deformation mechanism for (current) intereruptive periods at Cumbre Vieja, which would contribute positively to the stabilization of the edifice and reduce the associated hazard related to the volcano flank dynamics. This study at Cumbre Vieja can be considered as a prototype for similar volcanoes around the Macaronesian islands group (e.g., Fogo, Teide, El Hierro, Pico) and elsewhere.

González, Pablo J.; Tiampo, Kristy F.; Camacho, Antonio G.; Fernández, José

2010-09-01

104

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

NASA Astrophysics Data System (ADS)

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

Belousov, A.; Belousova, M.

2007-12-01

105

Measuring deformation associated with magmatic processes at Cerro Azul Volcano, Galapagos Islands, Ecuador with InSAR  

Microsoft Academic Search

The Galapagos Islands are an active volcanic island chain in the eastern Pacific Ocean off the west coast of Ecuador. Cerro Azul volcano is located on the southern tip of Isabella Island and experienced two eruptions in 10 years. The eruptions started on September 15, 1998 and May 29, 2008 and lasted 51 days and 20 days respectively. Using radar

S. Baker; F. Amelung

2009-01-01

106

Source Process of the Solomon Islands Earthquake of April 1st, 2007 (Mw8.1) Based on SAR Data and its Tectonic Implications  

NASA Astrophysics Data System (ADS)

We analyzed SAR (Synthetic Aperture Radar) data to derive the crustal deformation due to the Solomon Islands earthquake (Mw8.1) that occurred on April 1st, 2007. Three tracks that cover the source areas were used and the image data taken before and after the earthquake were processed to make interferograms. Then, we examined the obtained interferograms if the previous two source models that were obtained by seismic wave form inversion analyses could reproduce them. However, none of the models were able to reproduce the crustal deformations derived from the SAR data analysis. Then, we tried to construct a source model that explains the observed crustal deformations well. We considered some geophysical data to constrain the source geometry; the multichannel reflection data and observed vertical deformations using coral reef survey. Considering these lines of evidence, we introduced two possible source geometries; one is single-segment model that assumes only shallow-dipping (10 deg.) main thrust ruptured, and the other is two-segment model that assumes both a high angle spray fault of 30 degree dip and the main thrust fault slipped. The comparison of models based on inversion analyses suggested that the two-segment model would be preferable. This result suggests that the Solomon Islands earthquake would be the first observed earthquake on a steeply dipping splay fault that ruptured off the main converging plate boundary. If this is the case, this earthquake might provide us with an important clue for understanding the mechanisms of land formation such as landward titling of the coastal terraces.

Mori, M.; Kato, T.; Furuya, M.; Ochi, T.; Miyazaki, S.; Aoki, Y.

2008-12-01

107

Volcanoes  

NSDL National Science Digital Library

Volcanoes is part of an online series of modules entitled Exploring the Environment. Emphasizing an integrated approach to environmental Earth Science education through problem based-learning, this module asks students to look at four different situations involving volcanoes, research the situations, and make decisions about them. Information about the three volcanic areas under exploration (Mt. Hood, Kilauea, and Yellowstone) is given through maps, movies, and videos. Additional information covers plate tectonics, locations of volcanoes, volcano monitoring and hazards, how to deal with volcano threats, lavas, eruption types, and risk analysis. Once students have gone through the information, they make real-life decisions about building near volcanoes, and the possibility of eruptions in the near future. There are teacher resources, a reference for problem-based learning, and links for more information.

108

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

Microsoft Academic Search

Carbon dioxide (CO2) diffuse degassing structures (DDS) at Furnas volcano (São Miguel Island, Azores) are mostly associated with the main fumarolic fields, evidence that CO2 soil degassing is the surface expression of rising steam from the hydrothermal system. Locations with anomalous CO2 flux are mainly controlled by tectonic structures oriented WNW–ESE and NW–SE and by the geomorphology of the volcano,

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

2010-01-01

109

Volcanoes  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2005-12-17

110

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

NASA Astrophysics Data System (ADS)

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 related to the recurrent flank destabilizations, is linked to a deep sources, which can be either underlying crustal faults or the continuous downward subsidence of the Alizés intrusive complex.

Michon, Laurent; Saint-Ange, Francky

2008-03-01

111

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

NASA Astrophysics Data System (ADS)

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

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

2005-03-01

112

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

113

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

Microsoft Academic Search

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

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

2003-01-01

114

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

Microsoft Academic Search

We describe a methodology for identifying complex rift zones on recent or active volcanoes, where structures hidden by recent\\u000a deposits and logistical conditions might prevent carrying out detailed fieldwork. La Réunion island was chosen as a test-site.\\u000a We used georeferenced topographic maps, aerial photos and digital terrain models to perform a statistical analysis of several\\u000a morphometric parameters of pyroclastic cones.

Fabio Luca Bonali; Claudia Corazzato; Alessandro Tibaldi

2011-01-01

115

Newly discovered submarine flank eruption at Stromboli volcano (Aeolian Islands, Italy)  

Microsoft Academic Search

The NW submarine portion of Stromboli volcano has been investigated by deep-towed sidescan sonar, bathymetric surveys, video camera runs and dredging during two research cruises in 2002 and 2004. The surveys resulted in the identification of an extensive pillow lava field (106-107m3) at about 2300 m of water depth and 9 km from the shoreline of Stromboli Island. The pillow

A. Di Roberto; A. Bertagnini; M. Pompilio; F. Gamberi; M. P. Marani; A. M. Rosi

2008-01-01

116

White Island volcano, New Zealand: carbon dioxide and sulfur dioxide emission rates and melt inclusion studies  

Microsoft Academic Search

CO2 and SO2 emission rates are reported for the volcanic gas plume from White Island, the most active volcano in New Zealand. SO2 emission rates were measured 16 times by correlation spectrometer (COSPEC) from 1986 to 1999 and range from 171 to 900 Mg day?1. We estimate the average SO2 emission rate was 430±70 Mg day?1 between 1983 and 1999.

Lois J. Wardell; Philip R. Kyle; Nelia Dunbar; Bruce Christenson

2001-01-01

117

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

Microsoft Academic Search

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

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

2007-01-01

118

VOLInSAR-PF, the InSAR Volcano Observatory Service at Piton de la Fournaise Volcano (La Reunion Island).  

NASA Astrophysics Data System (ADS)

Since 2003, we carry out a systematic InSAR survey of the Piton de la Fournaise volcano, Reunion Island, in the framework of an AO-ENVISAT project. Since 2005 this activity gets the status of Observatory Service of the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC). From 375 ASAR images acquired between 2003 and 2010, we have produced more than 2100 interferograms that allowed us to map the deformations related to 21 eruptions and thus to better understand the internal processes acting during each eruption. In the same time, we have developed an automatic procedure to provide full resolution interferograms, trough a dedicated WEB site, to the Volcano Observatory of Piton de la Fournaise (OVPF), and our other partners, within a few hours after receiving the ASAR images. In this way, our work is a first step toward an operational system of InSAR monitoring of volcanic activity. Since the beginning of 2010, the VOLInSAR-PF database is also open to the entire community, trough an anonymous login that gives access to slightly reduced resolution interferograms. We will present the VOLInSAR-PF database, the main results it provides concerning the way Piton de la Fournaise is deforming, and the main perspectives for monitoring provided by the new InSAR data (PALSAR-ALOS, TerraSAR-X, RADARSAT-2, COSMO-Skymed) we are beginning to integrate in the database.

Froger, Jean-Luc; Cayol, Valérie; Augier, Aurélien; Souriot, Thierry

2010-05-01

119

Crustal structure of Deception Island volcano from P wave seismic tomography: Tectonic and volcanic implications  

NASA Astrophysics Data System (ADS)

Deception Island (62°59'S, 60°41'W) is an active volcano located in the Bransfield Strait between the Antarctic Peninsula and the South Shetland Islands. The island is composed of rocks that date from <0.75 Ma to historical eruptions (1842, 1967, 1969, and 1970), and nowadays most of its activity is represented by vigorous hydrothermal circulation, slight resurgence of the inner bay floor, and intense seismicity, with frequent volcano-tectonic and long-period events. In January 2005 an extensive seismic survey took place in and around the island to collect high-quality data for a high-resolution P wave velocity tomography study. A total of 95 land and 14 ocean bottom seismometers were deployed, and more than 6600 air gun shots were fired. As a result of this experiment, more than 70,000 travel time data were used to obtain the velocity model, which resolves strong P wave velocity contrasts down to 5 km depth. The joint interpretation of the Vp distribution together with the results of geological, geochemical, and other geophysical (magnetic and gravimetric) measurements allows us to map and interpret several volcanic features of the island and surroundings. The most striking feature is the low P wave velocity beneath the caldera floor which represents the seismic image of an extensive region of magma beneath a sediment-filled basin. Another low-velocity zone to the east of Deception Island corresponds to seafloor sedimentary deposits, while high velocities to the northwest are interpreted as the crystalline basement of the South Shetland Islands platform. In general, in the tomographic image we observe NE-SW and NW-SE distributions of velocity contrasts that are compatible with the regional tectonic directions and suggest that the volcanic evolution of Deception Island is strongly conditioned by the Bransfield Basin geodynamics.

Zandomeneghi, Daria; Barclay, Andrew; Almendros, Javier; IbañEz Godoy, Jesús M.; Wilcock, William S. D.; Ben-Zvi, Tami

2009-06-01

120

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

PubMed Central

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. Conclusion This study has demonstrated that the presence and abundance An. farauti larvae are influenced by environmental factors within the large streams. Understanding these parameters will allow for targeted cost effective implementation of source reduction and larviciding to support the frontline malaria control measures i.e. indoor residual spraying (IRS) and distribution of long-lasting insecticidal nets (LLINs).

2011-01-01

121

Discovery of an Active Submarine Mud Volcano Along the Nootka Fault West of Vancouver Island  

NASA Astrophysics Data System (ADS)

Submarine mud volcanoes are a common feature in margin environments, but few of them have been documented in the Northeast Pacific. However, during a Hydrosweep bathymetric survey in July, 2001, and a follow-on sub-surface seismic survey in August two mud volcanoes were imaged along the Nootka Fault, 16-18 km west of Vancouver Island at a water depth of 2500 m. The southern volcano, called Maquinna, lies directly along the southern expression of the left lateral, strike slip Nootka Fault. It is 1.5 km across, has a breached caldera and two small summit craters, and it stands about 30 m above the seafloor. The base is bounded by a narrow moat, partially filled by Holocene sediments that are flat lying; older, underlying sediments show steep downwarping towards the sides of the volcano. Subsurface imaging shows a dramatic loss of reflectivity beneath the volcano mound, which may indicate significant mobilization of material. However, a very bright reflector is seen at about 400 m depth below the volcano. This reflector is too deep for stability of methane clathrate, and is interpreted as a zone of high fluid content. A CTD vertical cast above the summit of the volcano showed strong, co-registered thermal, particulate, and oxygen anomalies that extend 50 m up into the overlying water column. These data indicate that the volcano is actively venting warm hydrothermal fluids. The fluids are depleted in CO2, contain background concentrations of CH4, but show elevated H2 concentrations above ocean background water. Microscopic examination of the Nootka hydrothermal samples shows that they contain dense and morphologically diverse microbial communities in comparison to background seawater with cell densities of 106 cells/ml. Enrichment culturing indicates that these communities include both anaerobic and aerobic organisms, some of which are thermophilic with optimal growth temperatures in excess of 50 deg C. Some of these cultures can use methane oxidation as an energy source. Additional culturing experiments and analysis of preserved samples are underway to further characterize the microbes. To further understand the biogeochemical cycles at these sites, samples recently taken from piston cores and CTD casts in this region, are being surveyed for stable and radio carbon isotope signatures of CH4, dissolved inorganic carbon, organic carbon and phospholipid bacterial biomarkers. A second volcano lies ~ 8 km to the northwest of the Maquinna that has a less well defined seafloor expression. However, like Maquinna, seismic reflectivity is lost nearly completely beneath the mound, except for a very bright reflector at about 800 m depth. It is not yet known if this volcano is hydrothermally active. It is likely that high sediment accumulation and lateral tectonic compression associated with accretionary prism formation along the west coast of Vancouver Island support overpressuring of fluids at depth along the Nootka Fault zone, resulting in growth of the two volcanoes.

Riedel, M.; Riedel, M.; Kelly, D. S.; Delaney, J. R.; Spence, G. D.; Hyndman, R. D.; Hyndman, R. D.; Mayer, L.; Calder, B.; Lilley, M. D.; Olson, E. O.; Schrenk, M. O.; Coffin, R.

2001-12-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

123

Carbon-14 ages of the past 20 ka of eruptive activity of Teide volcano, Canary Islands  

NASA Astrophysics Data System (ADS)

Teide volcano, the highest volcano on earth (3718 m a.s.l., >7 Km high) after Mauna Loa and Mauna Kea in the Hawaiian Islands, forms a volcanic complex in the centre of the Island of Tenerife. Its most recent eruptive activity (last 20 Ka) is associated with the very active NW branch of the 120º triple rift system of the island. Most of the eruptions of Tenerife during the past 20 ka have occurred along this volcanic feature, frequently in the production of extensive mafic and felsic lava flows, many of which reached the coast, crossing what is now one of the most densely populated areas of Tenerife and of any oceanic island in the world. However, despite numerous previous studies, very important basic geological information is still lacking, in particular dating of these flows to construct a geochronological framework for the evolution of the Teide-NW rift system, and a scientifically based, much needed volcanic hazard assessment. New carbon-14 ages, obtained via coupled mass spectrometer, and others in process, provide important time constraints on the evolution of Teide's volcanic system, the frequency and distribution of its eruptions, and the associated volcanic hazards. Most of the eruptions are not related to the Teide stratovolcano, which apparently had only one eruption in the last 20 Ka about 1240 ± 60 years BP, but to the Pico Viejo volcano (17570 ± 150 years BP), flank parasitic vents (Mña. Abejera upper vent, 5170 ± 110 years BP; Mña. Abejera lower vent, 4790 ± 70 years BP; Mancha Ruana, 2420 ± 70 years BP; Mña. La Angostura, 2010 ± 60 years BP and Roques Blancos, 1790 ± 60 years BP) and the NW rift (Mña. Chío, 3620 ± 70 years BP). Although the volcanic activity during the past 20 ka included the involvement of at least 7 voluminous phonolitic flank vents in the northern, more unstable slopes of the Teide, it took place without any apparent response of the volcano; on the contrary, these eruptions seemed to progressively buttress and enhance the stability of Teide Volcano. Conversely, the occurrence of these flank eruptions, combined with the Pico Viejo and NW rift eruptions, poses a very high lava-flow risk to the now densely populated areas to the north and west of Tenerife, which have been almost entirely resurfaced during the past 20.000 years.

Carracedo, J. C.; Guillou, H.; Paterne, M.; Pérez Torrado, F. J.; Paris, R.; Badiola, E. R.

2003-04-01

124

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

125

Solomons Field Branch.  

National Technical Information Service (NTIS)

The report describes the Naval Surface Weapons Center (White Oak Laboratory) Solomons Field Branch at Solomons, Maryland. Major test ranges and support facilities of the Field Branch are presented and their operations are described. The report is divided ...

T. D. Calderwood

1975-01-01

126

Ocean noise triggering of rhythmic long period events at Deception Island volcano  

NASA Astrophysics Data System (ADS)

We report on swarms of repeating long-period (LP) events with remarkably periodic occurrence at Deception Island volcano, Antarctica. The LP events show dominant frequencies near 2 Hz and characteristic inter-event times that range from ˜10 s to ˜20 s for individual swarms. We observe that LP inter-event times are approximate integer multiples of the dominant periods of the oceanic microseism, indicating a synchronization of LP activity with the phase of ocean noise. We attribute LP periodicity to the coincidence of sustained LP activity in an unstable hydrothermal system and external forcing by ocean noise that introduces periodic pressure variations in volcano fluids. We estimate the volumetric strain change generated by the oceanic microseism at the source location and conclude that strain of order 10-7 is sufficient to introduce clear periodicity in the LP sequences, and that periodicity increases with increasing strain.

Stich, Daniel; Almendros, Javier; Jiménez, Vanessa; Mancilla, Flor; Carmona, Enrique

2011-11-01

127

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

128

Elements of Pacific public health laws: an analysis of the public health acts of Papua New Guinea, Vanuatu, the Solomon Islands, and Fiji.  

PubMed

Pacific countries are sovereign nations with distinctive histories, ethnicity, customs, primary resources, economies, and health systems. Despite these and other acknowledged differences, similarities exist in many areas such as geography, legal history, and culture. Many share the experience of colonization, with imported British laws and the subsequent experience of independence. Most Pacific countries are also developing countries. This article broadly describes approaches to legislating in public health in Papua New Guinea, Fiji, Vanuatu, and the Solomon Islands and notes common elements in their public health laws, in particular, in relation to administration, allocation of powers and responsibilities, interaction with local government, communicable disease control, and nuisance. The article concludes that many Pacific public health laws could deliver better support for current health policy, more sensitivity to the culture and customs of the region, and better management of public health risk through laws that are better suited to their Pacific environment, easier to understand, more flexible, and more relevant to current health policy. PMID:23093516

Howse, Genevieve

2012-09-01

129

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

PubMed

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

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

2010-03-28

130

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)

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.

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

2010-05-01

131

Multiparametric Approach in Investigating Volcano-Hydrothermal Systems: the Case Study of Vulcano (Aeolian Islands, Italy)  

NASA Astrophysics Data System (ADS)

Seismic activity, ground deformation, and soil and fumarole temperatures acquired during 2004-2007 at Vulcano (Aeolian Islands) are analysed and the time relations among the different time series are discussed. Changes in temperature of fumarolic gases took place during four "anomalous" periods (November 2004-March 2005; October 2005-February 2006; August-October 2006; July-December 2007) at the same time as an increasing number of volcano-seismic events. In particular, the temperatures at high temperature vents and at steam heated soil ranged in time from 180 to 440°C and from 20 to 90°C, respectively. The maximum daily number of volcano-seismic events was 57, reached during the second anomalous period. This seismicity, characterised by focal depth generally lower than 1 km below sea level (b.s.l.) and composed of different kinds of events associated to both resonance and shear failure processes, is related to the shallow dynamics of the hydrothermal system. During the analysed period, very few volcano-tectonic earthquakes took place and tilt recordings showed no sharp or important changes. In light of such observations, the increases in both temperature and volcano-seismic events number were associated to increases in the release of gas from a deep and stable magma body, without magma intrusions within the shallow hydrothermal system. Indeed, a greater release of gas from depth leads to increased fluid circulation, that can promote increases in volcano-seismic events number by both fracturing processes and resonance and vibration in cracks and conduits. The different trends observed in the measured geochemical and geophysical series during the anomalous periods can be due to either time changes in the medium permeability or a changing speed of gas release from a deep magma body. Finally, all the observed variations, together with the changing temporal distribution of the different seismic event kinds, suggest that the hydrothermal system at Vulcano can be considered unsteady and dynamic.

Cannata, Andrea; Diliberto, Iole Serena; Alparone, Salvatore; Gambino, Salvatore; Gresta, Stefano; Liotta, Marcello; Madonia, Paolo; Milluzzo, Vincenzo; Aliotta, Marco; Montalto, Placido

2012-01-01

132

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

USGS Publications Warehouse

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.

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

1976-01-01

133

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

NASA Astrophysics Data System (ADS)

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

LeMasurier, Wesley

2013-06-01

134

Volcano  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on volcanoes and the destruction that results from eruptions. Students are given a scenario of massive volcanic destruction and have to come up with a plan to help those affected by the events. Included are objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

Weisel, Frank

135

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

Microsoft Academic Search

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

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

2007-01-01

136

Physical volcanology and structural development of Cerro Azul Volcano, Isabela Island, Galápagos: implications for the development of Galápagos-type shield volcanoes  

Microsoft Academic Search

Cerro Azul is an active basaltic shield volcano forming the southwestern end of Isabela Island in the western Galápagos Archipelago. Ten eruptions have been witnessed between 1932 and 1998, an average of one eruption every 6.6years. Although Cerro Azul has been constructed primarily by effusive Hawaiian-style eruptions, explosive hydrovolcanic eruptions have occurred intermittently from vents on the caldera floor and

Terry Naumann; Dennis Geist

2000-01-01

137

Impact of permethrin-impregnated mosquito nets compared with DDT house-spraying against malaria transmission by Anopheles farauti and An.punctulatus in the Solomon Islands.  

PubMed

In villages of northern Guadalcanal in the Solomon Islands, where the predominant malaria vector is An.farauti No. 1 and An.puctulatus is also involved, malaria transmission rates were compared for three zones: (1) non-intervention: 438 people in seventeen villages; (2) residual DDT house-spraying two cycles per year: 644 people in thirty villages; (3) bednets impregnated with permethrin 0.5 g/m2 twice per year, used by 580 people in sixteen villages. Regular DDT spraying in zones 1 and 3 had been withdrawn 18 months previously. Malariological blood smear surveys of children aged 1-9 years in August 1986 to January 1987 showed a mean baseline malaria parasite rate of 38% (32/84). By February 1988, 18 months after introduction of impregnated bednets, the Plasmodium falciparum infection rate in children was lowest in the zone using impregnated bednets (21% of 29), intermediate in the untreated zone (29% of 34) and highest in the DDT zone (46% of 53), but these differences were not statistically significant. P. vivax infection rates were 9-14%. Using ELISA tests for malaria circumsporozoite antigen in the vectors, overall positivity rates were 0.7% of 49,902 An.farauti and 2.54% of 118 An.punctulatus, comprising 228 P.falciparum and 124 P.vivax infections. In the study zones, vector positivity rates were 0.93% of 31,615 An.farauti in the untreated zone; 0.32% of 16,883 An.farauti in the DDT zone; 0.07% of 1404 An.farauti and 2.54% of 118 An.puctulatus in the impregnated bednet zone. here was no significant correlation between malaria parasite rates in the vectors and the children.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8268487

Hii, J L; Kanai, L; Foligela, A; Kan, S K; Burkot, T R; Wirtz, R A

1993-10-01

138

Tephrostratigraphy and petrological study of Chikurachki and Fuss volcanoes, western Paramushir Island, northern Kurile Islands: Evaluation of Holocene eruptive activity and temporal change of magma system  

Microsoft Academic Search

A tephrostratigraphic and petrological study of the Chikurachki (1816m)-Tatarinov-Lomonosov volcanic chain (CTL volcanic chain) and Fuss (1772m), located at the southern part of Paramushir Island in the northern Kurile Islands, was carried out to reveal the explosive eruption history during the Holocene and the temporal change of the magma systems of these active volcanoes. Tephra successions were described at 54

Takeshi Hasegawa; Mitsuhiro Nakagawa; Mitsuhiro Yoshimoto; Yoshihiro Ishizuka; Wataru Hirose; Sho-ichi Seki; Vera Ponomareva; Rybin Alexander

139

Radon-222 from the island of hawaii: deep soils are more important than lava fields or volcanoes.  

PubMed

The mean flux of radon-222 atoms from the island of Hawaii is 0.45 atom per square centimeter per second. Lava fields occupy 50 percent of the land area, but their radon flux is only 1 percent of that from deep volcanic soils. The island yields approximately 10 curies of radon-222 per hour to the air surrounding it. The radon-222 contribuition of volcanoes is negligible. PMID:17781932

Wilkening, M H

1974-02-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2006-01-01

141

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

Microsoft Academic Search

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,

A Searl; A Nicholl; P J Baxter

2002-01-01

142

Changes in vector species composition and current vector biology and behaviour will favour malaria elimination in Santa Isabel Province, Solomon Islands  

PubMed Central

Background In 2009, Santa Isabel Province in the Solomon Islands embarked on a malaria elimination programme. However, very little is known in the Province about the anopheline fauna, which species are vectors, their bionomics and how they may respond to intensified intervention measures. The purpose of this study was to provide baseline data on the malaria vectors and to ascertain the possibility of successfully eliminating malaria using the existing conventional vector control measures, such as indoor residual spraying (IRS) and long-lasting insecticidal nets (LLIN). Methods Entomological surveys were undertaken during October 2009. To determine species composition and distribution larval surveys were conducted across on the whole island. For malaria transmission studies, adult anophelines were sampled using human landing catches from two villages - one coastal and one inland. Results Five Anopheles species were found on Santa Isabel: Anopheles farauti, Anopheles hinesorum, Anopheles lungae, Anopheles solomonis, and Anopheles nataliae. Anopheles hinesorum was the most widespread species. Anopheles farauti was abundant, but found only on the coast. Anopheles punctulatus and Anopheles koliensis were not found. Anopheles farauti was the only species found biting in the coastal village, it was incriminated as a vector in this study; it fed early in the night but equally so indoors and outdoors, and had a low survival rate. Anopheles solomonis was the main species biting humans in the inland village, it was extremely exophagic, with low survival rates, and readily fed on pigs. Conclusion The disappearance of the two major vectors, An. punctulatus and An. koliensis, from Santa Isabel and the predominance of An. hinesorum, a non-vector species may facilitate malaria elimination measures. Anopheles farauti was identified as the main coastal vector with An. solomonis as a possible inland vector. The behaviour of An. solomonis is novel as it has not been previously found biting humans in any numbers. Both species appear to be short-lived, a characteristic that will limit their transmission potential. The early night feeding behaviour and a degree of outdoor biting seen in An. farauti and particularly in An. solomonis will require that their response to IRS and LLIN be closely monitored. In coastal villages, where large, favourable breeding sites allow for high numbers of An. farauti may require the addition of larval control to achieve elimination.

2011-01-01

143

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

NASA Astrophysics Data System (ADS)

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 can also be used to make new inferences as to the source characteristics of Anatahan magma. Trace element ratios Th/La and Sm/La distinguish island-to-island differences in the subducted sediment components incorporated into the Mariana arc magmas. Most Mariana volcanics plot on a mixing line between depleted mantle and the bulk subducting sediment Th/La (0.14). Anatahan, however, mixes to slightly higher Th/La (0.16), which could be caused by the shallow loss of the top 50 m of the sedimentary column (pelagic clay) during subduction.

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

2003-12-01

144

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

NASA Astrophysics Data System (ADS)

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.

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

2006-12-01

145

Using numerical modeling to explore the origin of intrusion patterns on Fernandina volcano, Galapagos Islands, Ecuador  

NASA Astrophysics Data System (ADS)

Using parameterized finite element models, we investigate the emplacement of both radial and circumferential intrusions in the configuration observed at Fernandina volcano in the Galapagos Islands. When situated within the edifice at depths consistent with petrological and surface displacement data, inflation of a mildly oblate magma reservoir to the point of rupture can initiate either radial or circumferential intrusions in response to minor, volcanologically plausible variations in reservoir geometry (i.e., aspect ratio). In addition, more oblate reservoirs inject lateral sills into an inflation-derived stress field consistent with rotation about their propagation axis to form gently dipping radial dikes, a mode of behavior recently inferred from InSAR data at Fernandina. All three styles of intrusion occur in near-surface configurations consistent with field observations.

Chestler, Shelley R.; Grosfils, Eric B.

2013-09-01

146

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

Microsoft Academic Search

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

Christopher F. Waythomas

1999-01-01

147

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

NASA Astrophysics Data System (ADS)

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 several sub-aerials deposits of debris avalanches. These new data, the analysis of geology and sedimentary figures observed within the breccia units in the “cirque de Salazie”, evidence several major gravitational collapse affecting the northeast flank of Piton des Neiges volcano. Considering that, the “cirque de Salazie” appears as partly bounded by gravitational collapse affecting the flanks of the volcano.

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

2003-04-01

148

The 2002–2003 submarine gas eruption at Panarea volcano (Aeolian Islands, Italy): Volcanology of the seafloor and implications for the hazard scenario  

Microsoft Academic Search

A submarine gas eruption started in November 2002 offshore of Panarea volcano (Aeolian Islands, Italy). The intensity of the gas emission and the considerable anomalies of the geochemical and geophysical parameters have alarmed the volcanological community and the Italian Civil Protection Agency on the possibility that this activity may represent a volcanic unrest at Panarea volcano. We used a high

Alessandra Esposito; Guido Giordano; Marco Anzidei

2006-01-01

149

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

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

150

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

USGS Publications Warehouse

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.

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

2011-01-01

151

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

NASA Astrophysics Data System (ADS)

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 fragmentation.

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

2007-09-01

152

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

SciTech Connect

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

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

1993-09-01

153

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

Microsoft Academic Search

Akutan Volcano is one of the most active volcanoes in the Aleutian arc, but until recently little was known about its history\\u000a and eruptive character. Following a brief but sustained period of intense seismic activity in March 1996, the Alaska Volcano\\u000a Observatory began investigating the geology of the volcano and evaluating potential volcanic hazards that could affect residents\\u000a of Akutan

Christopher F. Waythomas

1999-01-01

154

The 1976 1982 Strombolian and phreatomagmatic eruptions of White Island, New Zealand: eruptive and depositional mechanisms at a `wet' volcano  

Microsoft Academic Search

White Island is an active andesitic-dacitic composite volcano surrounded by sea, yet isolated from sea water by chemically sealed zones that confine a long-lived acidic hydrothermal system, within a thick sequence of fine-grained volcaniclastic sediment and ash. The rise of at least 106 m3 of basic andesite magma to shallow levels and its interaction with the hydrothermal system resulted in

B. F. Houghton; I. A. Nairn

1991-01-01

155

Measuring deformation associated with magmatic processes at Cerro Azul Volcano, Galapagos Islands, Ecuador with InSAR  

NASA Astrophysics Data System (ADS)

The Galapagos Islands are an active volcanic island chain in the eastern Pacific Ocean off the west coast of Ecuador. Cerro Azul volcano is located on the southern tip of Isabella Island and experienced two eruptions in 10 years. The eruptions started on September 15, 1998 and May 29, 2008 and lasted 51 days and 20 days respectively. Using radar data from Radarsat-1 and Envisat satellites, the deformation before, during, and after these eruptions was measured using interferometric synthetic aperture radar (InSAR). Radarsat-1 data cover the 1998 eruption and Envisat data is available in 2008. Compared to the 2008 data, the time coverage for the 1998 eruption is not as frequent, but still allows for measuring the deformation during the eruption. Continuous radar data coverage between the eruptions allows us to see the state of the volcano leading up to the 2008 eruption. Using data from 8 different Envisat tracks in 2008, we measured the deformation associated with two separate eruptive phases of the volcano. Acquisitions on May 30 and 31, and June 2, 3, 5 and 6 show the deformation associated with the intrusion of magma responsible for fissures on the SE flank ceased by June 5, 2008. Using these data, it is possible to measure the amount of deformation during each of the eruptive phases and model the source processes at those times.

Baker, S.; Amelung, F.

2009-12-01

156

Barren Island Volcano (NE Indian Ocean): Island-arc high-alumina basalts produced by troctolite contamination  

NASA Astrophysics Data System (ADS)

Barren Island (BI) is a subduction-related volcanic island lying in the northeastern Indian Ocean, about 750 km north of the northern tip of Sumatra. Rising from a depth of ˜2300 m on the Andaman Sea floor, BI has a submarine volume estimated at ˜400 km3, but the island is just 3 km across, reaches a maximum elevation of 355 m, and has a subaerial volume of only ˜1.3 km3. The first historical eruption began in 1787 when a cinder cone grew in the center of a pre-historical caldera 2-km in diameter and sent lava flows westward to reach the sea; activity continued intermittently until 1832. Two subsequent eruptions modified the central cone and also sent lava flows westward to reach the sea in 1991 and 1994 1995. A suite of 28 lava, scoria, and ash samples were investigated from various stages of the subaerial eruptive history of BI. Most are basalts (including all 10 samples from the 1994 1995 eruption) and basaltic andesites (including 7 of 8 samples from the 1991 eruption), but 2 pre-1787 andesites were also studied. On multi-element spider diagrams the BI suite shows subparallel trends for most elements that reflect an important role for fractional crystallization, along with the characteristic depletions of Nb Ta and enrichments of K Rb Pb found in other subduction-related island-arc suites. The typical relative enrichment of Ba is not present, likely because the subducted sediments in the Andaman arc are not Ba-rich. Wide compositional ranges for Cs, Th, Rb, U, and Pb may trace different degrees of scavenging from the underlying volcanic pile. BI basalts and basaltic andesites have variable abundances of phenocrystic microphenocrystic olivine plus Cr Al Mg spinel inclusions, plagioclase, and clinopyroxene, embedded in a matrix of glass, the same minerals, and titanomagnetite (mostly exsolved). The most remarkable mineralogical feature of certain BI basalts and basaltic andesites is the presence of abundant (to 40 vol.%) and large (to 5 mm) crystals of relatively homogeneous anorthitic plagioclase (to An95.7). These have inclusions of Mg olivine (to Fo79) and thin (10 150 ?m) normally zoned margins that reach to the more sodic compositions of the plagioclase phenocryst and microphenocryst rims. Anorthitic plagioclase crystals are common at many subduction-related volcanoes. At BI, the anorthitic plagioclase and associated olivine crystals are thought to have entered the magmas through disaggregation of troctolitic crystal mushes or plutonic xenoliths. This process affected bulk-rock compositions in many ways, including raising Al2O3 contents to values as high as 22.8 wt.% and Eu / Eu* values up to 1.05. Compared to a large petrological and geochemical database for Indonesian volcanic rocks, the BI suite falls at the most depleted end for levels of K and incompatible trace elements, and Sr, Nd, and Pb isotopic ratios. Consequently, the BI suite defines an excellent primitive baseline against which Indonesian volcanic suites can be compared.

Luhr, James F.; Haldar, Dhanapati

2006-01-01

157

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

158

Volcano-Tectonic History of the Island of Montserrat, West Indies, From Seismic Reflection Profiles  

NASA Astrophysics Data System (ADS)

Seismic reflection profiles provide a cross-sectional view of crustal layers and thus details about local sedimentation rates, chronology, and depositional materials. Based on seismic profiles collected as part of the SEA-CALIPSO seismic experiment, we apply this method to interpreting the volcanic and local tectonic history of the island of Montserrat, in the Lesser Antilles arc. In December 2007, the vessel RRS James Cook towed a tuned, 2600 cubic inch, 8-airgun array along encircling and radial lines around Montserrat. The airguns fired every 60 sec (approx. every 140 m) at a pressure of 2000 psi. The ship also towed a 600 m streamer consisting of 48 hydrophone channels. Over a period of 77 hours, the hydrophones recorded a total of 4414 shots. Onboard the ship, data were stacked to produce 26 seismic profiles. The profiles vary in length up to 15 km and allow interpretation up to a depth of approx. 2.5 km. The profiles from east of Montserrat reveal fans of coarse-grained debris flows and submarine pyroclastic flows that derive from both the older volcanic centers and the active Soufriere Hills Volcano (SHV). The flows form tapering wedges that have been overlain by younger sea-floor sediments. Older ( > 1 Ma) sedimentary rocks, containing multiple reflective layers, deflect downwards towards and beneath Montserrat, forming a moat into which the debris and pyroclastic flows have deposited. A sub-sediment volcanic basement is present offshore at approximately 1.5 km depth. Offshore on the west side of the island the prominent Belham valley fault can be traced trending NW. The new data suggest that the fault line has been active in the recent geological past; the fault has offset submarine deposits offshore and tectonic blocks onshore (Garibaldi Hill, St. Georges Hill, Roches Bluff), has caused the down-warping of ocean sediments on the east side of the island, and likely influenced the location of domes and feeding conduits at and adjacent to the SHV. Montserrat itself appears to be located at the SW boundary of a large half-graben.

Kenedi, C. L.; Sparks, S. J.; Dean, S.; Hammond, J.; Malin, P. E.; Minshull, T.; Paulatto, M.; Peirce, C.; Ryan, G.; Shalev, E.; Voight, B.

2008-12-01

159

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

160

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

USGS Publications Warehouse

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.

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

2003-01-01

161

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

162

Petrology and geochemistry of plinian basaltic volcanism of Chikurachki volcano, Kurile Islands, Russia  

Microsoft Academic Search

Plinian volcanism is characterized by high eruption rates commonly erupting gas-rich magmas of rhyolitic or dacitic composition. Plinian eruptions of basaltic composition are relatively rare and poorly studied. Chikurachki volcano (1816 m above sea level), the third of the highest active volcanoes of the Kurile arc, is characterized by both strombolian and plinian types of basaltic eruptions. Our goal is

A. A. Gurenko; A. B. Belousov; A. V. Sobolev

2003-01-01

163

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

Microsoft Academic Search

Fogo volcano, Cape Verde Islands, erupted in April 1995 after 43 years of dormancy. About 46 106 m3 of lava erupted during 7.5 weeks from vents on the SW flank of Pico do Fogo into Cha das Caldeiras. Interferograms obtained from 1993-1998 ERS SAR data show ground deformation due to the feeder dike but lack evidence for any volcano-wide deformation

Falk Amelung; Simon Day

2002-01-01

164

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

Microsoft Academic Search

Fogo volcano, Cape Verde Islands, erupted in April 1995 after 43 years of dormancy. About 46 106 m3 of lava erupted during 7.5 weeks from vents on the SW flank of Pico do Fogo into Cha das Caldeiras. Interferograms obtained from 1993–1998 ERS SAR data show ground deformation due to the feeder dike but lack evidence for any volcano-wide deformation

Falk Amelung; Simon Day

2002-01-01

165

The shallow magmatic system of Fernandina Volcano, Galápagos Islands. Evidence of multiple magma reservoirs from Satellite Radar Interferometry  

NASA Astrophysics Data System (ADS)

In the Galápagos Islands as at other ocean island volcanoes only a fraction of the magma coming from the mantle is erupted; the remaining magma is stored in crustal magma chambers, or trapped near the crust-mantle boundary. The increase of pressure generated by these magma intrusions can inflate the volcanic edifice and trigger eruptions and earthquakes. The geometry of magma reservoirs and their connections with the surface during eruptive phases, therefore, is fundamental to the development of predictive models of volcano deformation and eruption. Among the Galápagos Islands, Fernandina can be considered the most active volcano in the archipelago, having experienced 25 eruptions since 1813 and three eruptions in the last fifteen years (1995 - 2005 - 2009). In order to investigate the deformation associated with changes in pressure in the magma storage system we use Interferometric Synthetic Aperture Radar (InSAR) data acquired over Fernandina by the European Space Agency satellites ERS-1, ERS-2 and ENVISAT between 1992 and July 2010 in four different orbits. The advantage of using different viewing geometries is that the deformation signal can be independently validated and the responsible source beneath can be better constrained. We generate more than 300 interferograms and we apply the Small Baseline Subset (SBAS) method to investigate the temporal evolution of ground deformation. The analysis of single interferograms and of mean deformation velocity maps shows that the deformation at Fernandina is characterized by an almost continuous displacement of an elliptical area clearly limited by the summit caldera rim, and occasional displacement of a larger portion of the volcano edifice outside the caldera, around the summit. We then infer the presence of multiple sources of deformation below the summit caldera and the southern flank of Fernandina demonstrating that the magmatic system is composed by multiple magma reservoirs at different depths. We also determine an unusual shallow dipping geometry for the dike that fed the eruptive fissure opened on April 10, 2009 on the southwestern flank of the volcano, confirming what inferred by Jónsson et al. (1999) for the 1995 eruption.

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

2010-12-01

166

Ankaramitic Lavas and Clinopyroxene Megacrysts From the Tanganasoga Volcano, El Hierro Island (Canary Archipelago)  

NASA Astrophysics Data System (ADS)

Sometime between 134 and 21 ka, the volcanic edifice of El Hierro Island, the youngest, smallest and westernmost island of the Canary Archipelago, grew unstable and its north flank collapsed seaward to form the 15-km-wide El Golfo embayment. Since this event, eruptions at El Hierro have concentrated at the base of, and directly on, the landslide headwall and have commonly involved peculiar ankaramitic lavas rich in clinopyroxene and olivine crystals. The most striking examples of such eruptive products are located at the prominent Tanganasoga volcano, where at least ten eruptive vents have produced a large bulge in the centre-west part of the El Golfo embayment. Lava bombs from the northernmost craters reach up to ~1 m across and show extremely high crystal contents of up to 50 vol. %. Loose lapilli deposits found on the slopes of the cones contain large, often intact clinopyroxene crystals that frequently reach 1.5-2 cm, with the largest found being 3 cm across. We analyzed the whole-rock and groundmass composition of the ankaramites, as well as the composition of phenocryst phases. Moreover, four clinopyroxene megacrysts were studied in further detail, with > 300 electron microprobe spot analyses per crystal. Results indicate that groundmass and co-existing olivine and clinopyroxene crystals approach chemical equilibrium in terms of Fe-Mg exchange. Core-to-rim chemical profiles in the smaller crystals (< 1cm) reveal relatively homogeneous compositions of intra-sample crystal interiors. However, steep normal Fe-Mg zoning is common in the outermost 20-40 ?m of the crystals. In contrast, some crystals show reverse zoning towards the rim. Clinopyroxene thermobarometry indicate crystallization pressures of 700-900 MPa and temperatures of 1170-1220°C. The megacrysts show complex oscillatory zoning patterns, which, nonetheless, translate into modest chemical variations (Mg# = molar Mg/(Mg + Fetotal) = 76-80). We propose that the formation of Tanganasoga’s ankaramitic magmas and clinopyroxene megacrysts is the result of a complex interplay between prolonged magma storage, regular influx of fresh magma and efficient crystal growth, fractionation and accumulation at upper mantle depth. The eruption of such dense, crystal-rich magmas probably requires forceful triggering, and appears to be facilitated after large-scale landslide events.

Longpre, M.; Troll, V.; Hansteen, T. H.; Anderson, E.

2009-12-01

167

New insights on Mafate - Saint Gilles debris avalanche deposits (westward Piton des Neiges volcano Réunion Island)  

NASA Astrophysics Data System (ADS)

Studies of debris avalanche deposits on Reunion Island (southwestern Indian Ocean) have been started in the last decade with the bathymetric surveys offshore Piton de la Fournaise and the identification of giant submarine landslides (Lénat et al., 1989; Cochonnat et al., 1990). Since this discovery, new field investigations have been driven to characterise and understand the role of debris avalanche phenomena in the evolution of volcanic island like Reunion. The first aerial outcrop of debris avalanche deposits has been identified in the west part of Piton des Neiges volcano in 1996. It has been described has a succession of breccia events interbedded by lava flows, and localised in St Gilles area (Bachèlery et al, 2003). In the last two years, the breccia problematic has been revisited and new outcrops have been found in the northern and southern part of St Gilles area (Bret et al., 2003). In the light of new geological surveys, new debris avalanche deposits outcrops have been identified around the St Gilles area. Most of these new outcrops are situated in the main riverbeds of the western Piton des Neiges flank (Rivière des Galets, Ravine Divon, Ravine Bernica and Ravine Trois Bassins). Furthermore, similar breccia outcrops has been identified down the Maïdo cliff, in the walls of Mafate cirque, uphill St Gilles area. All these formations show common characters of debris avalanche deposits with (i) a “block facies” consisting of plurimetric to decametric shattered lava flow and dykes segments with typical jigsaw fractures packed in (ii) a “matrix facies” composed of silty to sandy heterogeneous elements. This tends to prove that previous authors have underestimated the St Gilles event lateral extent. Our new field surveys point out the new extension (obvious landslide scars) of the St Gilles well known debris avalanche deposits. These scars start in the Mafate cirque (where the landslide head is located), then continue through the Mafate wall in the north of Maïdo place and go down to the sea from Ravine Trois Bassins in the south to Rivière des Galets in the north. These discoveries associated to recent submarine DEM interpretation (Oehler, 2001) allow us to consider a new global evolution sketch of the whole Piton des Neiges west flank with a large debris-avalanche (now called Mafate - St Gilles debris avalanche deposits) that has recovered the former basaltic Piton des Neiges topography at the end of the shield building stage (around: 0.45 My).

Fèvre, F.; Bret, B.; Odon, O.; Arnaud, A.; Bachèlery, B.

2003-04-01

168

The SOLOMON computer  

Microsoft Academic Search

The SOLOMON (Simultaneous Operation Linked Ordinal Modular Network), a parallel network computer, is a new system involving the interconnections and programming, under the supervision of a central control unit, of many identical processing elements (as few or as many as a given problem requires), in an arrangement that can simulate directly the problem being solved.

Daniel L. Slotnick; W. Carl Borck; Robert C. McReynolds

1962-01-01

169

Unusual Signals Recorded by Ocean Bottom Seismometers in the Caldera of Deception Island Volcano: Biological Activity or Hydrothermally Generated Seismicity?  

NASA Astrophysics Data System (ADS)

As part of an active source land-sea tomography experiment, ocean bottom seismometers (OBSs) were deployed at Deception Island Volcano, Antarctica, in January 2005. Following the tomography study, three OBSs were left for a month inside the flooded caldera and ten on the outer slopes of the volcano to record seismo-volcanic signals. The OBS sensor package included three-orthogonal 1-Hz geophones but no hydrophone. The OBSs were deployed in water depths of 125 to 143 m inside the caldera and at depths of 119 to 475 m on the volcano's flanks. Only two volcano-tectonic earthquakes and three long period events were recorded by the network. However, the OBSs inside the caldera recorded over 4,500 unusual seismic events. These were detected by only one station at a time and were completely absent from OBSs on the flank of the volcano and from land stations deployed on the island. The signals had a dominant frequency of 5 Hz and were one to ten seconds long. Event activity in the caldera was variable with the number of events per hour ranging from 0 up to 60 and the level of activity decreasing slightly over the study period. We categorize the signals into three types based on waveform characteristics. Type 1 events have an impulsive onset and last 1 to 2 s with characteristics that are consistent with the impulse response of a poorly coupled OBS. Type 2 events typically last 2 to 4 s and comprise a low amplitude initial arrival followed less than a second later by a more energetic second phase that looks a Type 1 event. Type 3 events last up to 10 s and have more complex waveforms that appear to comprise several arrivals of varying amplitudes. Type 1 events are similar to the 'fish-bump' signals reported from previous studies that attributed them to biological activity. The consistent timing and relative amplitudes of the two arrivals for Type 2 events are difficult to explain by animals randomly touching the OBSs. Type 3 events are quite similar in frequency, duration, and signal characteristics to long-period seismic events recorded by an onshore seismic array deployed in an earlier study at Deception Island. Particle motions suggest that Type 3 events may be surface waves while the particle motions for Type 1 and Type 2 events are ambiguous and unlike any signals recorded by land arrays at the volcano. Binomial tests of the event distribution show no significant changes in the rate of events with time of day that would be indicative of a biological source. Since the events are entirely absent in biologically productive waters outside the caldera, we postulate that they may be volcanic signals related to hydrothermal flow across the seafloor in the flooded caldera of Deception Island. Future OBS deployments at Deception Island should include a hydrophone to discriminate unambiguously between biological and volcanic signals.

Bowman, D. C.; Wilcock, W. S.

2011-12-01

170

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

PubMed Central

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.

Fraile-Nuez, E.; Gonzalez-Davila, M.; Santana-Casiano, J. M.; Aristegui, J.; Alonso-Gonzalez, I. J.; Hernandez-Leon, S.; Blanco, M. J.; Rodriguez-Santana, A.; Hernandez-Guerra, A.; Gelado-Caballero, M. D.; Eugenio, F.; Marcello, J.; de Armas, D.; Dominguez-Yanes, J. F.; Montero, M. F.; Laetsch, D. R.; Velez-Belchi, P.; Ramos, A.; Ariza, A. V.; Comas-Rodriguez, I.; Benitez-Barrios, V. M.

2012-01-01

171

Monitoring Emissions at White Island Volcano, New Zealand; Evidence of Sustained Magmatic Degassing during Crater Lake Growth  

NASA Astrophysics Data System (ADS)

The commencement of routine monitoring of CO2 and SO2 emissions at White Island volcano in March 2003 indicated that degassing was at quiescent levels (880 and 225 td-1, respectively) similar to previous estimates of long-term (20-yr) emissions. Following an abrupt decrease in prolonged 2-5 Hz volcanic tremor in February, 2003, emissions decreased dramatically to ~250 and 0 td-1 CO2 and SO2, respectively. These decreases were coincident with the formation of a significant crater lake at the volcano. Since this time, however, CO2 emissions have increased and decreased by as much as an order of magnitude over periods of months with ~10 and 12 months between the lowest measured values. SO2 emissions also displayed similar variability, but changes were superimposed on a long term trend of increasing emissions. Likewise, SO4 concentrations in the crater lake increased steadily and also showed small deviations during periods of increased degassing. Crater lake temperatures varied primarily between 48 and 58 oC, but also displayed short-lived increases to 63 and 68 oC during periods of higher degassing. Similarly, modelled estimates of steam input to the lake, while varying, have remained relatively unchanged over the monitored period. Such changes suggest that a decrease in the magmatic mass and heat output from the volcano allowed the crater lake to form, but that overall, the mass and heat output have fluctuated about quiescent levels since the formation of the crater lake. White Island last erupted in 2000 marking the end of 25 years of episodic eruptions. We suggest that the variability of volatile output over timescales of months is related either to magma convection deep within the volcanic edifice or to changes in shallow permeability due to conduit saturation or mineral precipitation.

Werner, C. A.; Christenson, B. W.; Hurst, T.; Scott, B. J.; Britten, K.

2005-12-01

172

Spatial and temporal variations of soil CO2 flux and pressure gradient measurements at Cumbre Vieja volcano, La Palma, Canary Islands  

Microsoft Academic Search

La Palma (730 km2) is one of the youngest and the most active volcanic island of the Canarian archipelago. Volcanic activity has been concentrated on the southern part of the island, Cumbre Vieja volcano (220 km2), which had been constructed during the last 1 Ma. Three major volcanic rift-zones trending N-S, NW-SE and NE-SW constitute Cumbre Vieja's major structural features.

M. Brito; I. Martin; E. Padron; J. Salazar; P. Hernandez; N. Perez

2003-01-01

173

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

NASA Astrophysics Data System (ADS)

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 first arrivals and wide-angle reflections across the array. We will present a preliminary P-wave velocity model of the TE-2D data to constrain the middle to lower crust and upper mantle beneath Ross Island.

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

174

Hydrogen isotopic composition of hornblende and biotite phenocrysts from Japanese island arc volcanoes: Evaluation of alteration process of the hydrogen isotopic ratios by degassing and re-equilibration  

Microsoft Academic Search

In order to estimate hydrogen isotopic ratios (?D) of pre-eruptive island arc magma, we measured ?D, chemical compositions, and colour of hornblende and biotite phenocrysts from Japanese Quaternary volcanoes. The rock samples comprise lavas, lava domes, pyroclastic flow deposits related with lava dome collapse, air-fall pumices and pumice flow deposits. The observed ?D value ranges from ?108 to +103‰ SMOW

Isoji Miyagi; Osamu Matsubaya

2003-01-01

175

Lithospheric contributions to high-MgO basanites from the Cumbre Vieja Volcano, La Palma, Canary Islands and evidence for temporal variation in plume influence  

Microsoft Academic Search

New geochemical and isotopic data are presented from the oldest part of the Cumbre Vieja volcano, La Palma (Canary Islands), located near the assumed emergence of the Canary mantle plume. The volcanics comprise a suite dominated by basanite flows with subordinate amounts of phono-tephrite, tephri-phonolite and phonolite flows and intrusives. Two compositionally different basanite groups have been identified, both with

N.-O. Prægel; P. M. Holm

2006-01-01

176

The resource and development potential of the Makushin Volcano geothermal reservoir of the Aleutian Islands, Alaska  

SciTech Connect

Geological, geophysical, geochemical, and well flow-test data suggest a 13+- km/sup 3/ bulk volume, water-dominated, 195/sup 0/C geothermal reservoir that reaches a depth of 4.4+- km beneath the Makushin Volcano caldera. Through numerous fractures, this reservoir is presently discharging gases on the northern, eastern, and southern flanks of the volcano, as indicated by the occurrence of numerous fumaroles. Rising gases are also escaping directly to the surface through the caldera, as reflected by the largest fumarole field on the summit caldera.

Reeder, J.W.; Denig-Chakroff, D.N.; Economides, M.J.

1987-03-01

177

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

NASA Astrophysics Data System (ADS)

Kick 'em Jenny (KeJ) is an active submarine volcano located in the Lesser Antilles island arc, ~7.5 km northwest of Grenada. Of the twelve eruptions detected since 1939, most have been explosive as evidenced by eyewitness accounts in 1939, 1974, and 1988 and the dominance of explosive eruption products recovered by dredging. In 2003, vigorous hydrothermal activity was observed in the crater of KeJ. Video footage taken by a remotely operated vehicle (ROV) during the cruise RB-03-03 of the R/V Ronald Brown documented the venting of a vapor phase in the form of bubbles that ascended through the water column and a clear fluid phase in the form of shimmering water. The shimmering water generally ascended through the water column but can also been seen flowing down gradient from a fissure at the top of a fine-grained sediment mound. These fine-grained sediment mounds are the only structure associated with hydrothermal venting; spire or chimney structures were not observed. Hydrothermal venting was also observed coming from patches of coarse-grained volcaniclastic sediment on the crater floor and from talus slopes around the perimeter of the crater. Samples were collected from these areas and from areas void of hydrothermal activity. XRD and ICPMS analyses of bulk sediment were carried out to investigate the geochemical relationships between sediment types. Sediment samples from the hydrothermal mound structures are comprised of the same components (plagioclase, amphibole, pyroxene, and scoria) as sediment samples from areas void of hydrothermal activity (primary volcaniclastic sediment) in the 500-63 ?m size range. High resolution grain size analyses show that >78% of sediment in the hydrothermal mound samples are between 63-2 ?m with 6-20% clay sized (<2 ?m) whereas <40% of the primary volcaniclastic sediment is between 63-2 ?m with ~2% clay sized. The presence of clay minerals (smectite, illite, talc, and I/S mixed layer) in the hydrothermal mound samples was confirmed x-ray diffraction analysis. Differences in major oxide composition of the two sediment types (depletion in Al2O3 but enrichments in MgO and Fe2O3* in the mound sample relative to primary volcaniclastic sediment) suggest that mound sediment has experienced hydrothermal alteration/mineralization. Elevated concentrations of As, Sb and Cu in the mound sediment also indicate a strong hydrothermal contribution. The bulk composition of the mound sediment can be reasonably modeled as a mixture of ~78% primary volcaniclastic sediment, ~30% alteration clay minerals, and ~2% pyrite. The percentage of clay required in the model is ~10% greater than the fraction (~20%) observed in the hydrothermal mound sample but some of the alteration products may consist of larger grains that have not been analyzed individually.

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

2011-12-01

178

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

NASA Astrophysics Data System (ADS)

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

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

2005-08-01

179

Variations in Seismic Anisotropy with time on Volcanoes in Kyushu Island, Southern Japan  

Microsoft Academic Search

Using a newly developed automatic processing technique, we have calculated shear wave splitting on and near three active volcanoes in Kyushu, southern Japan (Aso, Unzen and Sakurajima). Shear wave splitting is considered to be caused by aligned cracks and microcracks. The polarisation of the first arriving phase, phi, gives a measure of the crack orientation, which is expected to align

M. K. Savage; T. Ohkura; K. Umakoshi; H. Shimizu; Y. Kohno; M. Iguchi; A. Wessel; J. Mori

2008-01-01

180

The western submerged sector of the Ischia volcanic island (Tyrrhenian Sea, Italy): new insights into its volcano-tectonic evolution  

NASA Astrophysics Data System (ADS)

The Island of Ischia is a volcanic complex located in the northern boundary of the Gulf of Naples (south-eastern Tyrrhenian Sea, Italy). The island represents only the 30% of a larger, E-W trending, volcanic ridge and likely controlled by a regional tectonic lineament. Despite the many geo-volcanological and geophysical investigations conducted on the island since long time, still little is the knowledge of its offshore. Several marine surveys have been carried out over the past 10 years from IAMC - CNR research institute (Naples, Italy) mostly in the frame of INGV and GNV projects, funded by Italy Civil Protection Department. Such surveys have largely improved the knowledge of the entire volcanic complex. Multibeam bathymetry surveys has revealed several, previously unexpected, morphological and morphostructural features. Moreover some structural patterns and volcano alignments offshore show similarities with those occurring at a regional scale in the Campania region and, locally, between the island of Procida and Phlegrean Fields. Here we report the joint interpretation of geophysical data focused on the western underwater sector of the island. Interpretation was chiefly based on processing/inversion of magnetic data in turn constrained by bathymetry and seismic reflection profiles. Magnetic data, acquired by the IAMC during two different cruises in 2000 and 2002 onboard of the Urania R/V oceanographic vessel, put in evidence that the western seafloor of Ischia is characterized by the presence of a strong residual magnetic anomaly field of complex behaviour, somewhere correlated to local bathymetry. These two last methods allowed to define and distinguish between undersea and subsurface magnetic (i.e. magmatic) basement. Interpretation was also constrained by seismological data.

Passaro, Salvatore; de Alteriis, Giovanni; Milano, Girolamo; Fedi, Maurizio; Florio, Giovanni

2010-05-01

181

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

PubMed Central

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

Searl, A; Nicholl, A; Baxter, P

2002-01-01

182

Variations in Seismic Anisotropy with time on Volcanoes in Kyushu Island, Southern Japan  

NASA Astrophysics Data System (ADS)

Using a newly developed automatic processing technique, we have calculated shear wave splitting on and near three active volcanoes in Kyushu, southern Japan (Aso, Unzen and Sakurajima). Shear wave splitting is considered to be caused by aligned cracks and microcracks. The polarisation of the first arriving phase, ?, gives a measure of the crack orientation, which is expected to align with the maximum principal stress. The delay time dt between the two phases depends upon the crack density and the path length. High quality measurements include the following: a) over 1700 from local events recorded and located near Aso Volcano between 2001 and 2008; b) over 2000 from local events recorded and located near Unzen volcano between 1988 and 1997 (spanning the most active period of seismic activity related to the large eruption in 1991); c) over 600 from regional events originating in the subducting Phillipine Sea plate recorded near Sakurajima volcano between 2003 and 2005, (during which time numerous small eruptions have occcurred, and GPS measurements have been modeled as caused by inflation of a Mogi source and a near-vertical crack). Most of the stations were located in boreholes or tunnels, providing excellent signals. Common features at all three volcanoes are that stations closest to the craters yield the fewest good measurements, and even those tend to give varying results at closely spaced stations. Scattering from the volcanic edifice may be making the S waves difficult to pick, and the local stresses may be varied. Stations on the volcanic flanks give many good measurements. Some stations yield variations in ? and dt that depend upon the earthquake location. But at each volcano, some stations show changes that are better explained by variations in time than in space. Where GPS measurements are available, the variations sometimes but not always correlate with previously-modeled inflation or deflation events. The temporal variations in ? are large, ranging from 30° at some stations to 90 ° at other stations. These results will allow us to test models of stress changes with time on the volcanoes.

Savage, M. K.; Ohkura, T.; Umakoshi, K.; Shimizu, H.; Kohno, Y.; Iguchi, M.; Wessel, A.; Mori, J.

2008-12-01

183

Shallow Seismic Attenuation and Shear Waves Splitting In The Short Period Range of Deception Island Volcano (antarctica)  

NASA Astrophysics Data System (ADS)

The occurrence of a seismic series in Deception Island volcano (Antarctica), com- posed by hundreds of local volcano-tectonic earthquakes, has permitted us to study the seismic attenuation of such a volcanic environment in the short-distance and high- frequency range. This study has been performed using P, S and coda waves and ap- plying different, frequency dependent and independent, techniques. The methods used for this analysis have been: Spectral and Broadening of the Pulse, for direct P and S waves, Coda Normalization for S-waves and Single Back-Scattering model for coda waves. The results show that, in general, Q values are significantly smaller, for all the frequency range used (6-30 Hz), than those found in other volcanic and tectonic areas. The attenuation for P-waves is greater than for S-waves in the frequency in- dependent methods, with a Qb/QP ratio that ranges between 1.9 and 3.2. Comparing the Q factor obtained for S-waves we have observed clear differences as a function of the method used; the Coda Normalization Method has supplied significantly higher Q values (Qd) than the other two methods (Qb). These Qd values are similar to the Q factor for coda waves (Qc). We have interpreted this discrepancy as an effect of the methods: Coda Normalization and Single Back-Scattering methods eliminate the con- tribution of the near surface attenuation in their Q values. Comparing both Qb and Qd we have estimated the near surface attenuation under the recording site, named Qk. On the other hand, we have observed that Qd has an anomalous frequency dependence, with a minimum value at 21 Hz. This pattern is interpreted as an effect of strong scat- tering of the seismic waves in the source area of the earthquakes. Qc values depend clearly with frequency and lapse time, and the lapse time dependence is interpreted as a depth dependence of the seismic attenuation in Deception Island volcano. The de- rived Q values have allowed us to separate the contribution of intrinsic and scattering attenuation, deriving that the scattering attenuation is predominant over the intrinsic effects. Finally, in order to investigate how the heterogeneous medium of the volcanic island could produce other effects, we have measured the splitting of the shear waves of the same data set. The observations reveal that the arrival delay of the shear waves horizontal components varies between 0.02 and 0.14 seconds, a big amount if we take into account the short hypocentral distances (less than 5 km). The study of the polar- 1 ization direction indicates a main E-W direction. All these evidences reveal the strong heterogeneous structure of Deception Island volcano. 2

Martínez-Arévalo, C.; Bianco, F.; Ibáñez, J. M.; del Pezzo, E.

184

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

Microsoft Academic Search

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

William W. Chadwick; Tui Roy; Alfredo Carrasco

1991-01-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

186

Beryllium geochemistry constraints on the hydraulic behavior of mud volcanoes: the Trinidad Island case  

NASA Astrophysics Data System (ADS)

To constrain Trinidad mud volcanoes hydraulic behavior, both cosmogenic 10Be (t1/2=1.5 Myr) and 9Be concentrations have been measured in fluid and associated expelled mud. As previously evidenced [A.N. Dia, M. Castrec, J. Boulègue, P. Comeau, Trinidad Mud Volcanoes: where do the expelled fluids come from? Geochim. Cosmochim. Acta 63 (1999) 1023-1038] from ?18O values and Cl concentrations, 9Be concentrations in the fluids mostly reflect the mixing of two deep components: REM I and REM II. REM I (?18O=10.5‰, Cl~275 mM and 9Be~0.05 nM) has characteristics of a continental fluid while REM II (?18O=3‰, Cl~350 mM and 9Be~1 nM) results from seawater-volcanogenic derived sediment interaction. Although 10Be concentrations in the fluid samples are close to the detection limit, the distribution of both beryllium isotopes between the hydroxylamine leachable and residual phases indicates exchange reaction with fluid younger than 15 Myr. Comparison between the lowest REM I 10Be/9Be ratio in fluid recorded by the hydroxylamine leachable phase (TD5 mud sample) and the 10Be/9Be ratio representative of meteoric contribution in the recharge area (TD8 fluid sample) yields a circulation rate of REM I fluid in the Trinidad mud volcanoes of several 10-1 m/yr.

Castrec-Rouelle, M.; Bourlès, D. L.; Boulègue, J.; Dia, A. N.

2002-11-01

187

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

188

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

USGS Publications Warehouse

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.

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

2010-01-01

189

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

190

Evaluation of morphometry-based dating of monogenetic volcanoes—a case study from Bandas del Sur, Tenerife (Canary Islands)  

NASA Astrophysics Data System (ADS)

Morphometry-based dating provides a first-order estimate of the temporal evolution of monogenetic volcanic edifices located within an intraplate monogenetic volcanic field or on the flanks of a polygenetic volcano. Two widely used morphometric parameters, namely cone height/width ratio ( H max/ W co) and slope angle, were applied to extract chronological information and evaluate their accuracy for morphometry-based ordering. Based on these quantitative parameters extracted from contour-based Digital Elevation Models (DEMs), two event orders for the Bandas del Sur in Tenerife (Canary Islands) were constructed and compared with the existing K-Ar, paleomagnetic and stratigraphic data. The results obtained suggest that the commonly used H max/ W co ratio is not reliable, leading to inappropriate temporal order estimates, while the slope angle gives slightly better results. The overall performance of such descriptive parameters was, however, generally poor (i.e. there is no strong correlation between morphometry and age). The geomorphic/morphometric mismatches could be the result of (1) the diversity of syn-eruptive processes (i.e. diverse initial morphologies causing geomorphic/morphometric variability), (2) contrasting, edifice-specific degradation that depends partly upon the inner facies architecture of the volcanic edifices, (3) various external environmental controls (e.g. tephra mantling from pyroclastic density currents unrelated to the edifice evaluated) and (4) differences in the scale/resolution of input data. The observed degradation trend and changes in morphometric parameters over time do not support a simple degradation model for monogenetic scoria cones volcanoes.

Kereszturi, Gábor; Geyer, Adelina; Martí, Joan; Németh, Károly; Dóniz-Páez, F. Javier

2013-07-01

191

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)

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.

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

192

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

Microsoft Academic Search

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

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

2011-01-01

193

The 1976–1982 Strombolian and phreatomagmatic eruptions of White Island, New Zealand: eruptive and depositional mechanisms at a ‘wet’ volcano  

Microsoft Academic Search

White Island is an active andesitic-dacitic composite volcano surrounded by sea, yet isolated from sea water by chemically sealed zones that confine a long-lived acidic hydrothermal system, within a thick sequence of fine-grained volcaniclastic sediment and ash. The rise of at least 106 m3 of basic andesite magma to shallow levels and its interaction with the hydrothermal system resulted in

B F Houghton; I A Nairn

1991-01-01

194

Long magma residence times at an island arc volcano (Soufriere, St. Vincent) in the Lesser Antilles: evidence from 238 U- 230 Th isochron dating  

Microsoft Academic Search

High-precision (TIMS) measurements of U and Th isotope concentrations have been determined on whole rocks and mineral separates from Soufriere volcano on St. Vincent in the Lesser Antilles island arc. The whole rocks display relatively constant U\\/Th ratios (~0.5), and are characterised by excess 238 U relative to 230 Th which is attributed to the addition of U-rich fluids from

E. Heath; S. P. Turner; R. MacDonald; C. J. Hawkesworth; P. van Calsteren

1998-01-01

195

Long magma residence times at an island arc volcano (Soufriere, St. Vincent) in the Lesser Antilles: evidence from 238U– 230Th isochron dating  

Microsoft Academic Search

High-precision (TIMS) measurements of U and Th isotope concentrations have been determined on whole rocks and mineral separates from Soufriere volcano on St. Vincent in the Lesser Antilles island arc. The whole rocks display relatively constant U\\/Th ratios (?0.5), and are characterised by excess 238U relative to 230Th which is attributed to the addition of U-rich fluids from the subducting

E Heath; S. P Turner; R Macdonald; C. J Hawkesworth; P van Calsteren

1998-01-01

196

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

Microsoft Academic Search

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

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

2008-01-01

197

Chemical composition, volatile components, and trace elements in melts of the Karymskii volcanic center, Kamchatka, and Golovnina volcano, Kunashir Island: Evidence from inclusions in minerals  

Microsoft Academic Search

Melt inclusions were examined in phenocrysts in basalt, andesite, dacite, and rhyodacite from the Karymskii volcanic center\\u000a in Kamchatka and dacite form Golovnina volcano in Kunashir Island, Kuriles. The inclusions were examined by homogenization\\u000a and by analyzing glasses in more than 80 inclusions on an electron microscope and ion microprobe. The SiO2 concentrations in the melt inclusions in plagioclase phenocrysts

V. B. Naumov; M. L. Tolstykh; E. N. Grib; V. L. Leonov; N. N. Kononkova

2008-01-01

198

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

Microsoft Academic Search

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

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

199

Petrology and geochemistry of plinian basaltic volcanism of Chikurachki volcano, Kurile Islands, Russia  

NASA Astrophysics Data System (ADS)

Plinian volcanism is characterized by high eruption rates commonly erupting gas-rich magmas of rhyolitic or dacitic composition. Plinian eruptions of basaltic composition are relatively rare and poorly studied. Chikurachki volcano (1816 m above sea level), the third of the highest active volcanoes of the Kurile arc, is characterized by both strombolian and plinian types of basaltic eruptions. Our goal is to place new petrological and geochemical constraints on the magma origin, as well as to understand the behavior of volatile components. Plinian fallout deposits resulting from the 1853, 1986 and ancient eruptions of Chikurachki volcano were a subject of this study. We analyzed major, trace and volatile (H_2O, S, Cl) elements in glass inclusions (up to 100 ?m in size) hosted in olivine (Ol, Fo72-78), orthopyroxene (Opx, mg# = 72--75), clinopyroxene (Cpx, mg# = 71--77) and plagioclase (Pl, An74-96) from glassy lapilli using EPMA and SIMS. Phenocryst crystallization occurred in the temperature range of 1140-1040^oC and oxygen fugacity around NNO. Glass inclusions have basalt to basaltic andesite composition, are enriched by LREE ([La/Sm]n = 1.2--1.5) and characterized by significant Nb depletion ([Nb/La]n = 0.18--0.27) and some Sr enrichment ([Sr/Ce]n = 2.0--3.8). Varying concentrations of H_2O (1.5--3.8 wt%), S (0.01--0.29 wt%) and Cl (0.05--0.14 wt%) suggest partial to strong degassing of the erupted magmas. The release of volatile components during eruption of such H_2O- and SO_2-rich magmas probably resulted in strongly explosive character of basaltic eruptions of Chikurachki. Trace element contents in glass inclusions were interpreted to reflect a mixture of at least two components during the magma origin: (1) a mantle component previously experienced partial melting and melt extraction and therefore depleted in LILE, LREE and Nb, and (2) a component containing H_2O and being enriched in potentially fluid-mobile elements e.g., Li, B and Ba. Neither contamination by upper crustal rocks or oceanic sediments nor by melts resulting from partial melting of the subducting slab can account the composition of the erupted magmas. The processes of fluid release from the subducting slab beneath the Kurile arc followed by metosomatism of the mantle wedge and its consequent melting are discussed.

Gurenko, A. A.; Belousov, A. B.; Sobolev, A. V.

2003-04-01

200

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)

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 km3 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 km3/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km3) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing geomorphic process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major process in the morphological evolution of Réunion Island that has to be fully integrated in future studies.

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

2012-01-01

201

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

PubMed

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. PMID:12493195

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

2003-01-01

202

Volcano Live  

NSDL National Science Digital Library

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

Seach, John

203

Volcano-Tectonic History of the Island of Montserrat, West Indies, From Seismic Reflection Profiles  

Microsoft Academic Search

Seismic reflection profiles provide a cross-sectional view of crustal layers and thus details about local sedimentation rates, chronology, and depositional materials. Based on seismic profiles collected as part of the SEA-CALIPSO seismic experiment, we apply this method to interpreting the volcanic and local tectonic history of the island of Montserrat, in the Lesser Antilles arc. In December 2007, the vessel

C. L. Kenedi; S. J. Sparks; S. Dean; J. Hammond; P. E. Malin; T. Minshull; M. Paulatto; C. Peirce; G. Ryan; E. Shalev; B. Voight

2008-01-01

204

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

NASA Astrophysics Data System (ADS)

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.

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

2009-09-01

205

Implications of Temporal-Compositional Variations in the Cerro Pajas Flow and Cone, Floreana Volcano, Galapagos Islands  

NASA Astrophysics Data System (ADS)

Floreana Island is a unique volcano in the Galapagos Islands due to its abundance of mantle xenoliths and the compositional imprint of mantle metasomatism. Floreana lavas are also the most alkaline in the archipelago and represent an enriched end-member due to their high 87Sr/86Sr and 206Pb/204Pb isotope ratios and high concentrations of incompatible trace elements. The surface exposure age of the lavas ranges from 1.52 Ma to 26 ka. Detailed mapping of a single eruptive unit, the Cerro Pajas sequence, shows 18 different eruptive units consisting of lava lobes and tephra. The age of the Pajas units is 26 ka. A suite of nineteen samples was collected from each of the flow lobes and tephra in order to assess variations over the course of the eruptive event. By studying the temporal-compositional trends of a heterogeneous eruptive sequence on Floreana, the melting mechanisms at Floreana can be assessed. Large variations in MgO concentration are seen over the course of the eruption, implying possible differences in the extent of differentiation. The beginning and end of the eruption show the highest concentrations of MgO (~11.5 wt. %). Most of the eruption, however, produced lavas with MgO concentrations of about 7.5 wt. %. The change in MgO cannot simply be attributed to different proportions of olivine phenocrysts, but must reflect changes in liquid composition. In general, concentrations of incompatible elements and ratios such as Nb/Zr increased over the course of the eruption by an amount greater than can be accounted for by fractional crystallization. This may be the result of a decrease in the degree of partial melting over the course of the eruption, and reveals that compositional heterogeneity is generated during a single melt extraction event and preserved during ascent through the lithosphere.

Sabga, M.; Ruiz Paspuel, A.; Geist, D.; Harpp, K.; Koleszar, A.

2007-12-01

206

Rock fall photogrammetric monitoring in the active crater of Piton de la Fournaise volcano, La Reunion Island  

NASA Astrophysics Data System (ADS)

The collapse of the active crater at Piton de la Fournaise volcano, La Reunion Island, 5th April 2007, offers a rare opportunity to observe frequent rock fall and granular landslides, and test new monitoring techniques. Events concern volumes ranging from single blocks to more massive cliff collapse. The purpose of the presentation is two fold: first, we present a comparison between a Digital Terrain Model (DTM) obtained prior to crater collapse and a DTM extracted from aerial photographs shot in October 2010 (before the eruptive crisis of November 2009 and January 2010). This provides an assessment of morphological changes at the scale of the crater. The second purpose is to describe slope instabilities on the south-western flank of the crater observed since October 2009. These ground-based observations were obtained from a pair of photogrammetric stations deployed along the northern and eastern edges of the crater. These works were conducted within UNDERVOLC project. With this monitoring system we mapped zones affected by rockfalls (departure and accumulation areas) and propose a first estimate of volumes of lava produced by the eruption affecting the inside of the crater since January 2.

Hibert, Clément; Dewez, Thomas; Mangeney, Anne; Grandjean, Gilles; Boissier, Patrice; Catherine, Philippe; Kowalski, Philippe

2010-05-01

207

A Summary of Geothermal Exploration and Data from Stratigraphic Test Well No. 1 Makushin Volcano, Unalaska Island  

SciTech Connect

Geothermal resource investigations have been conducted for the past four years on Unalaska Island in the Aleutian Chain. The focus of the work has been Makushin Volcano, about 12 miles from the cities of Unalaska and Dutch Harbor. In the summer of 1982, three widely spaced deep temperature gradient holes were drilled which encountered high temperatures. During the summer of 1983, a three inch diameter "slim hole" well, ST-1, was drilled to 1,949 feet. A shallow, low pressure, steam zone and a relatively productive hot water zone at total depth were encountered. The lower zone produced 47,000 lb/hr, limited by reaching critical mass velocity at the orifice. The static bottomhole pressure and temperature were 478 psig and 379{degrees}F, respectively. Analysis of transient pressure and flow data yielded a productivity inex of 3,470 lb/hr/psi and a permeability-thickness of 50,900 md-ft for the three-foot (at the wellbore) lower zone fracture. A preliminary reservoir/wellbore flow evaluation for a possible power plant indicates two commercial-size wells could fuel a 10 megawatt facility.

Campbell, Don A.; Economides, Michael J.

1983-12-15

208

Biodegradation of Crude Oil by Thermophilic Bacteria Isolated from a Volcano Island  

Microsoft Academic Search

One-hundred and fifty different thermophilic bacteria isolated from a volcanic island were screened for detection of an alkane\\u000a hydroxylase gene using degenerated primers developed to amplify genes related to the Pseudomonas putida and Pseudomonas oleovorans alkane hydroxylases. Ten isolates carrying the alkJ gene were further characterized by 16s rDNA gene sequencing. Nine out of ten isolates were phylogenetically affiliated with

Christos Meintanis; Kalliopi I. Chalkou; Konstantinos Ar. Kormas; Amalia D. Karagouni

2006-01-01

209

Volcanoes in the Infrared  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2009-02-27

210

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

211

Characterization of fracture systems using precise array locations of earthquake multiplets: An example at Deception Island volcano, Antarctica  

NASA Astrophysics Data System (ADS)

Volcano-tectonic earthquakes are common seismic events in active volcanic areas. The stress produced by volcanic processes is released through fracturing of the shallow crust. Very often, these earthquakes occur in multiplets with similar waveforms, a fact which indicates common source characteristics. In this work, we introduce a method that uses array techniques to calculate precise relative locations of earthquake multiplets. We use the relative slowness estimate method to determine accurately the apparent slownesses and propagation azimuths of the earthquakes relative to a selected master event. We also obtain precise estimates of the S-P delays. This information is used to calculate precise relative locations by ray tracing in an Earth model. We applied this method to determine the characteristics of the fractures activated during the 1999 seismic series at the Deception Island volcano, Antarctica. We selected a set of 17 earthquake multiplets, initially located in a small (4 × 4 km) region a few km NE of the array site. We estimated precise locations for 14 of the clusters. In most cases, hypocenters were distributed in well-defined planar geometries. We found the best fitting planes, which we interpreted as fractures in the medium. For two clusters, the method spatially separated the earthquakes into two subgroups. Thus, we obtained two planes for each of these clusters, resulting in a total of 16 fracture planes. This is the first time that the orientations of fracture planes related to a seismic series have been obtained using a seismic array. We performed several tests to check various aspects in relation to the stability of the method and concluded that the results were robust. The dip angles indicate that the planes are mostly subvertical, while the strike angles clearly show a NW-SE trend for most of the planes and a few planes with NE-SW trends. The geometry and position of these planes suggest that the 1999 seismic series was influenced by regional tectonics, although the origin of the destabilization of the system may be related to the reactivation of a shallow magma chamber.

Carmona, E.; Almendros, J.; PeñA, J. A.; IbáñEz, J. M.

2010-06-01

212

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

NASA Astrophysics Data System (ADS)

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.

Huang, F.; Lundstrom, C. C.

2005-12-01

213

Fault model of the 2007 Solomon earthquake estimated from the crustal deformation survey data  

NASA Astrophysics Data System (ADS)

On April 1, 2007, a large earthquake occurred off the Solomon Islands along the Solomon subduction zone. The earthquake generated a large tsunami that killed more than 40 people in Gizo and Simbo Islands near the epicenter. The one day aftershock distribution showed that the source region was located in the subduction zone where the Woodlark ridge system subducted beneath the Pacific plate. Because of the subduction of the ridge, no trench exists near the plate boundary. Instead, two Islands, Simbo and Ranongga Islands, exist unusually close to the plate boundary. About two week after the earthquake, the Japanese survey team was in the Solomon Islands to conduct the coseismic deformation survey in Gizo, Simbo, Ranongga, Vella Lavella, and Kilimbangara Islands near the source area of the 2007 Solomon earthquake. A whole island of Ranongga was uplifted by the earthquake because a large area of coral flats around the island was now appeared above high tide levels. In Simbo Island, located about 20km south of Ranongga Island, we found small subsidence. In Vella Lavella Island, the most part of the island was subsided except the most southeast tip of the island. In Gizo Island, the small subsidence was found along the most part of the coast. Using those crustal deformation data, we estimated that the strike of the fault is 315 degree, the width of the fault is 35 km, the dip of the fault is about 35 degree which is much larger than a typical dip of the plate interface near a trench, the shallowest edge of the fault is located between Simbo and Renongga Islands, and the depth of the shallowest edge is less than 5km. This unusual splay fault type earthquake occurred in this area where the Woodlark ridge subducted beneath the Pacific plate.

Tanioka, Y.; Namegaya, Y.; Nishimura, Y.; Yoshinobu, T.; Nakamura, Y.; Murata, M.; Woodward, S.

2007-12-01

214

Variability In The Solomon Sea From Altimetric Sea Level Data  

NASA Astrophysics Data System (ADS)

In the southwest tropical Pacific, subtropical waters from the SEC flow in the Solomon Sea, mainly through the western boundary New Guinea Coastal Undercurrent, and join the equatorial western Pacific by three narrow straits. The NGCU transports part of the spiciness anomalies generated in the South East Pacific and subducted in the thermocline. Because the NGCU is a primary source of the EUC, variations of its characteristics are expected to play a role in the equatorial thermocline features and more generally on decadal climate variability. Therefore, the study of the Solomon Sea is a key issue of the SPICE program. In this study, we focus on the variability of the Solomon Sea in term of sea level. The Solomon Sea is semi closed with a complex topography and numerous islands. Thus, the use of classical gridded altimetric products is inadequate. Consequently, this work is based on original along track Topex/Poseidon data. New data processing (CTOH/LEGOS) has been applied to recover proper data and to gain more information on the altimetric signal in this region. A track-by-track specific and customized post processing has been used to finalize the dataset. These new altimetric data have been assessed against tide gauge data. The analysis of the resulting sea level anomalies exhibits the highest variability observed in the tropical Pacific in an area centred near 8°S and expanding from each side of the Solomon Islands, outside of the WBC. Sea level variability presents a wide temporal spectrum, from intraseasonal to interannual ranges with the notable influence of the monsoon and of ENSO. In the Solomon Sea, three frequencies emerge : 60, 365 and 2000 days. The 60-days frequency seems particularly important in the Solomon Sea compared with the surrounding waters and an EOF analysis is used to understand its features. We also depict the signature of the New Guinea Coastal Current (NGCC), the western boundary current flowing north along the eastern coast of Papua New Guinea, which is particularly important for the connection to the equator. In parallel to this study, a hierarchy of high resolution (1/4°, 1/12°) regional models is also being built. The altimetric dataset will be used to perform a realistic simulation of the region circulations through data assimilation.

Melet, A.; Gourdeau, L.; Kessler, W.; Verron, J.

2007-12-01

215

K–Ar analyses of the post-caldera lavas of Bratan volcano in Bali Island, Indonesia — Ar isotope mass fractionation to light isotope enrichment  

NASA Astrophysics Data System (ADS)

The post-caldera lavas of Bratan volcano in Bali Island, Indonesia were collected for whole rock chemical analyses and K–Ar analyses. Major and trace element chemistry shows that the lavas are basalts to andesites and typical of subduction-related tectonic setting. The 38Ar/36Ar ratios are 0.1851 ± 3–0.1875 ± 2 and the 40Ar/36Ar, 294.3 ± 0.3–301.6 ± 0.1, which strongly suggest that the mass fractionation to light isotope enrichment took place. The effect of the groundwater on magma is common on the basis of systematic mass fractionation of the atmospheric Ar enriched in lighter isotopes. This case was under the mass fractionation law analyzed numerically, giving the mass fractionation correction ages (14 ± 15, 31 ± 6, 55 ± 22, 66 ± 23, 94 ± 32 and 125 ± 51 ka) consistent with the volcano stratigraphy though the magma composition that changed frequently in time.

Ryu, Sunyoung; Kitagawa, Hiroshi; Nakamura, Eizo; Itaya, Tetsumaru; Watanabe, Koichiro

2013-08-01

216

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

USGS Publications Warehouse

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.

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

1991-01-01

217

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

NASA Astrophysics Data System (ADS)

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

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

1990-09-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

219

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

Microsoft Academic Search

On March 15th 2007 a paroxysmal explosion occurred at the Stromboli volcano. This event generated a large amount of products, mostly lithic blocks, some of which impacted the ground as far as down to 200ma.s.l., about 1.5km far away from the active vents. Two days after the explosion, a new vapour emission was discovered on the north-eastern flank of the

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

2010-01-01

220

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)

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

Day, S. J.

2011-12-01

221

Earth's Active Volcanoes by Geographic Region  

NSDL National Science Digital Library

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

222

On Hyperbolic Cascaded Reed-Solomon Codes  

Microsoft Academic Search

This paper describes a class of two-dimensional codes called cascaded Reed-Solomon (CRS) codes and an algorithm for decoding these codes up to their minimum distance. CRS codes are cascade (or generalized concatenated) codes in which Reed-Solomon codes are used for both the inner and outer codes. We introduce hyperbolic cascaded Reed-Solomon (HCRS) codes, which have maximal rate among CRS codes

Keith Saints; Chris Heegard

1993-01-01

223

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)

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

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

2011-12-01

224

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  

Microsoft Academic Search

New mapping and 60 new radiocarbon ages define the age and distribution of latest Pleistocene and Holocene (past 13,000 years) lava flows at Haleakala 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

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

2006-01-01

225

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)

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

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

2010-05-01

226

Eruptive history of western and central Aeolian Islands volcanoes (South Tyrrhenian Sea, Italy): temporal evolution of magmatism and of morphological structures  

NASA Astrophysics Data System (ADS)

The Aeolian Island archipelago is a complex volcanic province located on the continental margin of the Calabro-Peloritan basement. It emplaced in a geodynamic setting linked to the convergence of African and European plates. In this study, we focused on the western and central volcanoes that are respectively Alicudi-Filicudi-Salina and Lipari-Vulcano. They erupted the whole range of magmas typical of convergence settings : from calc-alkaline (CA) to potassic series (KS) through high-K CA (HKCA) and shoshonitic series (SHO). All these magma products were emitted in a span time of less than 300 ka that attests to the complexity of the volcano-tectonic evolution of this province. We report new geochronological data, based on the K/Ar Cassignol-Gillot technique, which is well suited for dating Quaternary volcanic materials. New geochemical analyses were realized on the dated samples in order to study the temporal evolution of the magmatism. These data sets were coupled with geomorphological analysis to study the relation between main morphological structures and eruptive styles. Before 180 ka, only the Filicudi, Salina and Lipari volcanoes had emerged activity. Their magmas have relatively the same CA composition, whereas some Lipari lavas have early HKCA affinity. Around 120-130 ka, Alicudi and Vulcano emerged simultaneously at the extremities of the archipelago. Alicudi products are less various and have the more primitive composition. SHO and HKCA products were emitted on Lipari and Vulcano, while only CA magmas were emplaced on Filicudi and Salina. After 40 ka, the last activity of Filicudi is characterized by mafic magmas of HKCA affinity. To the other extremity, similar products of SHO affinity were emplaced in southern Lipari and northern Vulcano. At this period, explosive activity with dacitic pumices occurred in Salina. The degree of differentiation and the K enrichment increase from western sector to central sector volcanoes and through time except at Filicudi. At the scale of the archipelago, two main magma composition changes occurred around 120 and 40 ka. However, at smaller space and time-scales, the magmatic evolution is more complex reflecting different processes specific to each volcano.

Leocat, E.; Gillot, P.; Peccerillo, A.

2010-12-01

227

Volcanoes Galore!  

NSDL National Science Digital Library

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

Syracuse, Mr.

2008-06-11

228

Flow directions and emplacement temperatures of Holocene phreatomagmatic deposits at Stromboli volcano (Aeolian islands, Italy) inferred by paleomagnetic analyses  

NASA Astrophysics Data System (ADS)

Stromboli volcano is presently characterized by persistent mild explosive activity. However the most dangerous scenario at Stromboli is associated to the lateral sector collapse of the volcano, a less frequent event that permits the magma-water interaction producing very explosive phreatomagmatic eruptions. At Stromboli volcano, the phreatomagmatic deposits have been, up to now, related to the same eruptive event occurred in the last 15 ka. We carried out the results from an AMS (14 sites) and a TRM (8 sites) analyses on Holocene phreatomagmatic and surge deposits. Two stratigraphic sections (Secche di Lazzaro and COA) in two different localities have been recognized and investigated by means of stratigraphic, sedimentological and magnetic analyses. The magnetic fabric data suggest that the basal part of the Secche di Lazzaro deposit was emplaced from a diluted phreatomagmatic pyroclastic flow coming from the sea, whereas the middle and upper part from the summit vent. The thermal remanent magnetization data of the lava lithics demonstrate that the whole deposit was emplaced at very low temperatures (less than 140°C), whereas the basal part of the COA deposit was emplaced at temperatures between 300-350°C. The overall results suggest that the two investigated deposits are related to two distinct eruptive events, occurred in the last 15 ka. In this case, the recent phreatomagmatic activity at Stromboli should be occurred more frequently than previously believed, suggesting to reconsider the timing of recurrence of this dangerous eruptive scenario for the Stromboli volcano.

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

2006-12-01

229

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

230

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)

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.

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

2013-05-01

231

Inflation and deflation modeling at Sierra Negra and Fernandina volcanoes based on GPS measurements. Galapagos Islands, Ecuador  

NASA Astrophysics Data System (ADS)

Continuous Global Positioning System (CGPS) network established since 2002 on Sierra Negra and the campaign GPS network re-measured in 2006 on Sierra Negra and Fernandina volcanoes allowed for the evaluation of ground deformation after the 2005 eruptions on each volcano. In contrast, shallow seismicity detected before the eruptions by the Galapagos seismic network (REDGAL) may be related to a shallow, pressurized magma chamber fed by a deep source on each volcano, while regional seismicity, by National Earthquake Information Center-United States Geological Survey (NEIC-USGS), plays no measurable role in the ground deformation. The ground deformation monitored by the CGPS network on Sierra Negra demonstrated fast inflation of ~ 212 cm/y immediately after the October 2005 eruption and then a deceleration at rates of ~ 73 cm/y in 2006 and ~ 48 cm/y in 2007 due the pressurization of the shallow sill. This is supported by micro-gravity surveys performed in 2006 and 2007 which record a large density increase (magma influx and/or densification) centered above the shallow sill immediately following the eruption. The density increase continued in 2007 but at a slower rate. Inversion and calculations using a simple elastic model indicates a sill ~ 2 km depth oriented northeast-southwest in agreement with InSAR data, and an average rate of magma intrusion of ~ 70 x 106 m3 /y. The campaign GPS dataset on Fernandina volcano is best explained by an average rate of magma intrusion of ~2.2 x 106 m3/y, and the deformation is best modeled by a magma chamber ~ 2 km deep in combination with a dike source produced by the May 2005 eruption. The integration of these methods allowed us to see the volcanic activity from the depth to the surface on each volcano and construct a conceptual model for each one after the 2005 eruptions.

Ruiz Paspuel, A. G.; Geist, D.; Chadwick, W.; Johnson, D.; Vigouroux-Caillibot, N.; Harpp, K. S.; Batt, S.

2010-12-01

232

Decoding of Reed-Solomon Codes.  

National Technical Information Service (NTIS)

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 ...

R. J. Mceliece

1988-01-01

233

Long-term explosion records from two erupting submarine volcanoes in the Mariana and Tonga island-arcs  

NASA Astrophysics Data System (ADS)

Records of explosive activity longer than a few weeks are rare for subaerial volcanoes, and nonexistent for submarine volcanoes. From February 2008 to February 2009, we recorded a year long, continuous acoustic and volcanic plume record from NW Rota-1, an erupting submarine volcano located within the Mariana Arc. From December 2008 to May 2009, we also obtained acoustic records of ongoing explosion and tremor activity at West Mata, a submarine volcano in the NE Lau basin near the Tofua volcanic-arc. At NW Rota-1, a hydrophone and turbidity/temperature sensor were moored ~150 m from the volcano’s summit vent (520 m deep). The volcano exhibited frequent degassing explosions lasting 60-120 s, separated by quiet periods of 10-30 s, for the entire 12-months resulting in >284,000 discrete explosion events. The explosions are broadband (1-80 Hz) with typical source levels of 191 dB re ?Pa @ 1m. Harmonic tremor is also present at times in the explosions, typically with <5 Hz fundamentals and extremely high-amplitude overtone peaks near 30 Hz. The fundamentals are likely due to resonance of the entire volcanic edifice, while the peak overtone may represent reverberation of an internal structure, possibly the conduit feeding the summit vent. The hydrophone also documents a 103 decrease in explosion amplitude over the year, marked by a sharp reduction after 6 mos, which may be part of the typical eruption cycle or due to burial of the vent by accumulated ejecta. Explosions at the summit vent produced a steady series of volcanic plumes that carried ash and hydrothermal precipitates into the water column. Hundreds of short-lived turbidity spikes are present, with no long periods of quiescence, indicating changes in explosion intensity did not affect the pattern of volcanic plume creation. Our data are the first to confirm the frequent creation and dispersal of submarine volcanic plumes on a year-long scale. In December 2008 a moored hydrophone (250 Hz) was deployed ~30 km from West Mata, a near-arc boninite volcano discovered actively erupting the month before. An ROV cruise in May 2009 deployed two short-term, high-frequency (1024 Hz) hydrophones within 50 m of the Hades volcanic vent (1208 m deep). Both the long-term and in situ hydrophones detected explosive activity as well as both mono- and polychromatic volcanic tremor throughout their records. ROV video shows the acoustic signals are from violent degassing bursts from within lava extruding at the Hades vent (summit of West Mata). The explosions exhibit both short (10s of sec) and long (2-10 min) duration modes of cyclic activity. Many explosion signals also show harmonic tremor within their codas indicative of resonance from within the volcanic edifice. Frequently the explosion records are overlapped by monochromatic tremor from a narrow band within a range from 20-100 Hz. The source of this resonance is not yet clear (although not man-made) and is possibly from a nearby, unseen vent or magma movement within the volcanic edifice.

Dziak, R. P.; Embley, R. W.; Baker, E. T.; Chadwick, W. W.; Resing, J.; Matsumoto, H.; Walker, S. L.; Bohnenstiehl, D. R.; Klink, H.

2009-12-01

234

HIGH TEMPERATURE VOLCANIC GAS GEOCHEMISTRY (MAJOR AND MINOR ELEMENTS) AT KUDRYAVY VOLCANO, ITURUP ISLAND, KURIL ARC, RUSSIA  

Microsoft Academic Search

Kudryavy volcano is well known for its famous Re-enrichment (Korzhinsky et al., 1994). Degassing occurs along 2 main fumarolic fields: field A enriched in Re (T= 400 to 700°C) and field B enriched in Mo (T= 600-940°C). The fO2 values of the volcanic gases are close to the Ni\\/NiO buffer. Direct fO2 measurements over the temperature range 500- 950°C approach

F. Africano; A. Bernard; M. Korzhinsky

2003-01-01

235

Constraints on magma chamber geometry at Sierra Negra Volcano, Galápagos Islands, based on InSAR observations  

Microsoft Academic Search

We investigate the problem of estimating magma chamber geometry using InSAR observations of Sierra Negra Volcano, Galápagos. Ascending and descending interferograms are combined to determine vertical and one horizontal component of displacement. The ratio of maximum horizontal to vertical displacement suggests a sill-like source. Spherical or stock-like bodies are inconsistent with the data. We estimate the geometry of the sill

S. Yun; P. Segall; H. Zebker

2006-01-01

236

Life at the extreme: meiofauna from three unexplored lakes in the caldera of the Cerro Azul volcano, Galápagos Islands, Ecuador  

Microsoft Academic Search

On Isla Isabela, Galápagos Archipelago, three so far unexplored lakes were investigated in the caldera of Cerro Azul, one\\u000a of the most active volcanoes in the world. The lakes face recurrent desiccation and eruption events and showed distinct differences\\u000a in their water chemistry. Thirty cores from the upper 15 cm of sediment indicate distinct differences in the composition of\\u000a meiobenthic communities

Daniel Muschiol; Walter Traunspurger

2009-01-01

237

The November 2002 eruption at Piton de la Fournaise volcano, La Réunion Island: ground deformation, seismicity, and pit crater collapse  

Microsoft Academic Search

An eruption on the eastern flank of Piton de la Fournaise volcano started on 16 November, 2002 after 10 months of quiescence.\\u000a After a relatively constant level of activity during the first 13 days of the eruption, lava discharge, volcanic tremor and\\u000a seismicity increased from 29 November to 3 December. Lava effusion suddenly ceased on 3 December while shallow earthquakes\\u000a beneath the

Marc-Antoine Longpré; Thomas Staudacher; John Stix

2007-01-01

238

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

NASA Astrophysics Data System (ADS)

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.

Sherrod, David R.; Murai, Takashi; Tagami, Takahiro

2007-04-01

239

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

USGS Publications Warehouse

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.

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

2007-01-01

240

Hydrogeology of Stromboli volcano, Aeolian Islands (Italy) from the interpretation of resistivity tomograms, self-potential, soil temperature and soil CO2 concentration measurements  

NASA Astrophysics Data System (ADS)

To gain a better insight of the hydrogeology and the location of the main tectonic faults of Stromboli volcano in Italy, we collected electrical resistivity measurements, soil CO2 concentrations, temperature and self-potential measurements along two profiles. These two profiles started at the village of Ginostra in the southwest part of the island. The first profile (4.8 km in length) ended up at the village of Scari in the north east part of the volcano and the second one (3.5 km in length) at Forgia Vecchia beach, in the eastern part of the island. These data were used to provide insights regarding the position of shallow aquifers and the extension of the hydrothermal system. This large-scale study is complemented by two high-resolution studies, one at the Pizzo area (near the active vents) and one at Rina Grande where flank collapse areas can be observed. The Pizzo corresponds to one of the main degassing structure of the hydrothermal system. The main degassing area is localized along a higher permeability area corresponding to the head of the gliding plane of the Rina Grande sector collapse. We found that the self-potential data reveal the position of an aquifer above the villages of Scari and San Vincenzo. We provide an estimate of the depth of this aquifer from these data. The lateral extension of the hydrothermal system (resistivity ˜15-60 ohm m) is broader than anticipated extending in the direction of the villages of Scari and San Vincenzo (in agreement with temperature data recorded in shallow wells). The lateral extension of the hydrothermal system reaches the lower third of the Rina Grande sector collapse area in the eastern part of the island. The hydrothermal body in this area is blocked by an old collapse boundary. This position of the hydrothermal body is consistent with low values of the magnetization (<2.5 A m-1) from previously published work. The presence of the hydrothermal body below Rina Grande raises questions about the mechanical stability of this flank of the edifice.

Revil, A.; Finizola, A.; Ricci, T.; Delcher, E.; Peltier, A.; Barde-Cabusson, S.; Avard, G.; Bailly, T.; Bennati, L.; Byrdina, S.; Colonge, J.; di Gangi, F.; Douillet, G.; Lupi, M.; Letort, J.; Tsang Hin Sun, E.

2011-09-01

241

Structure and change of Piton de la Fournaise volcano inferred from gravity surveys (Reunion Island, Indian Ocean)  

NASA Astrophysics Data System (ADS)

A new gravity map of Piton de la Fournaise volcano has been established using new on land and offshore measurements. The data coverage allows for the differentiation of shallow and deeper structures. 3D and 2 3/4 D models have been calculated. Short wavelength positive anomalies depict the presence of piles of thick dense lava flows filling volcano-tectonic depressions. The lateral extension and the depth of paleo- depressions associated with the collapses of the Plaine des Sables-Fond de la Rivière de l'Est and of the Enclos Fouqué are thus estimated. The negative short wavelength of the Central Cone suggests it has been built by thin, highly vesisculated and fractured lava flows. Low density hydrothermally altered rock beneath the summit can also contribute to the gravity low as well as a column of fractured rocks between the surface collapse and a magma reservoir. Negative short to medium wavelength anomalies have been observed in the Rivière des Remparts-Rivière Langevin zone and above the offshore continuation of the NE and SE rift zones. We speculate that the former zone is underlain by breccias related to erosion or mass- wasting events. The offshore continuation of the rift zones is most likely built by hyaloclastites and pillow lavas. Two main deeper dense structures exist: the Grand Brûlé complex and a complex beneath the Plaine des Sables and part of the Enclos. From a deep drill-hole it has been established that the Grand Brûlé complex is a hypovolcanic complex of intrusions and cumulates. We show that this structure is disconnected from the present day Piton de la Fournaise volcano. Its interpretation as the hypovolcanic complex of the ancient concealed Les Alizés volcano remains valid. The similar nature of the other dense complex is inferred by analogy with comparable anomalies in this geological context and by the presence of frequent gabbro and peridotite xenoliths in eruptive products in this area. We suggest that this complex has developed during the Ancient Shield period of Piton de la Fournaise. The fact that this structure is apparently not offset by the fault that limits the Enclos to the west suggests that the latter is a listric fault. Observed apparent contradictions between the seismic tomographies and the gravity pattern could be resolved considering the relative sensitivity of each method. Strong shallow gravity signals significantly hide moderate signals from deeper structures. Conversely, with a moderate station and signal coverage, the seismic tomographies fail to define precisely the subsurface structures. The use of both methods increases the accuracy in the determination of the internal structure of volcanoes. Pre and post April 2007 eruptive and volcano-tectonic crisis data show a significant gravity change in the central area. The observed mass deficit can be explained by creation of the new Dolomieu crater only or by the sum of the effects of the crater formation and of the fracturing of a column of rocks between the surface and the drained magma reservoir.

Lénat, J.; Gailler, L.; Lambert, M.; Levieux, G.; Villeneuve, N.; Froger, J.

2008-12-01

242

Gravity Variations at a Dynamic Basaltic Caldera: Before and After the 2005 Eruption of Sierra Negra Volcano, Galapagos Islands  

NASA Astrophysics Data System (ADS)

Sierra Negra volcano, an active basaltic volcano in the western Galapagos, last erupted in October 2005 following a period of accelerated uplift of the central caldera floor that started in April 2003. Deformation data indicate that a shallow (~ 2 km) sill underlies the caldera floor, and an intrusion rate of 64 x 106 m3/y for the 6 months prior to eruption was calculated from a continuous GPS network installed in 2002. Micro-gravity measurements were conducted in 2005, 2006, and 2007 at three stations in the center of the caldera and one station on the outer flank of the volcano and referenced to a base station on the NE rim of the caldera. From June 2005 to June 2006, residual gravity measured in the caldera increased by 1500 microgals at the center of the caldera to 184 microgals halfway to the northern edge of the caldera. This increase in residual gravity (height corrected) was accompanied by an uplift rate of ~ 212 cm/y until February 2006 after which the uplift rate decreased to 73 cm/y in 2006 and 44 cm/y in 2007. Similarly, from June 2006 to June 2007 gravity increased less dramaticaly than in 2005-2006 with an average increase of 11 microgals at the center of the caldera and 132 microgals at the more northern part of the caldera. Interestingly, the center of maximum gravity change shifted from the center of the caldera to the northern part sometime between June 2006 and June 2007. Gravity measurements on the outer rim of the caldera showed a 300 and a 200 microgal decrease from June 2005 to June 2006 and June 2006 to June 2007, respectively accompanied by low rates of inflation (1.8 cm/y). The coupling of gravity and deformation change supports the hypothesis of significant mass increase in the central-northern part of the caldera.

Geist, D.; Vigouroux, N.; Williams-Jones, G.; Chadwick, W.; Johnson, D.

2007-12-01

243

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

NASA Astrophysics Data System (ADS)

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

Ortiz, R.; Vila, J.; García, A.; Tárraga, M.; Carniel, R.; Marrero, J. M.; Carmona, J.; Fernández-Ros, A.; Berrocoso, M.

2009-04-01

244

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

NASA Astrophysics Data System (ADS)

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.

Bagnardi, Marco; Amelung, Falk

2012-10-01

245

Efficient standard basis Reed-Solomon encoder  

Microsoft Academic Search

This paper presents an efficient Reed-Solomon encoder based on standard basis. The key operation in Reed-Solomon encoding is the multiplication of a feedback term with several (possibly) known terms. We present an efficient structure to implement this operation. The hardware complexity of this encoder is identical to the well-known Berlekamp encoder. It however, offers two advantages over the Berlekamp encoder-a

S. K. Jain; Keshab K. Parhi

1996-01-01

246

Subspace Subcodes of Reed-Solomon Codes  

Microsoft Academic Search

In this paper we introduce a class of nonlinear cyclic error-correcting codes, which we call subspace subcodes of Reed-Solomon (SSRS) codes. An SSRS code is a subset of a parent Reed-Solomon (RS) code consisting of the RS codewords whose components all lie in a fixed -dimensional vector subspace of GF SSRS codes are constructed using properties of the Galois field

Masayuki Hattori; Robert J. Mceliece; Gustave Solomon

1998-01-01

247

The 226Ra-230Th-238U disequilibria of enigmatic magmas from Piton de la Fournaise Volcano, Reunion Island (1950-1998)  

NASA Astrophysics Data System (ADS)

We present a detailed study of the 226Ra-230Th-238U disequilibria and selected incompatible trace-element abundances of lavas from Piton de la Fournaise, a frequently active ocean-island volcano, using high-precision MC-ICP-MS. The samples erupted between 1950-1998 from vents within the summit caldera (Enclos Fouque) or along the rift zones of the volcano. The lavas display a significant range in 226Ra-230Th disequilibria (25-33% excess 226Ra) and 230Th-238U disequilibria (14-20% excess 230Th). The (230Th/232Th) ratios of the lavas are relatively constant (0.9% range) and do not correlate with either Th/U or (230Th/238U). A strong correlation (R2=0.97) between the (230Th/238U) and Th/U ratios suggests that most of the Th-U fractionation in these lavas occurred recently compared to the 76 kyr half-life of 230Th [because the effects of this fractionation are not yet reflected in the (230Th/232Th) ratios]. In contrast, the 226Ra-230Th disequilbria do not correlate with the Ba/Th ratios of the lavas (a geochemical analog). Thus, the range in Ba/Th (6.1%) and (226Ra/230Th) ratios probably results from either more than one magmatic process or a single process operating over a time scale that is longer than the half-life of 226Ra (1600 years). Unlike Hawaiian shield volcanoes, which display systematic temporal geochemical variations on a time scale of decades to centuries, the fluctuations in lava chemistry at Piton de la Fournaise do not display any coherent trends over the last 50 years. Some geochemical parameters [e.g., Ba/U, Nd/Sm or (230Th/238U)] do vary systematically over a period of a few years, but these trends are not observed consistently for the same samples and different geochemical parameters. The origin of these complex variations in lava chemistry at Piton de la Fournaise is enigmatic, but probably includes a combination of mantle (Albarede and Tamagnan, 1988, J. Petrol. v. 29) and crustal (Sigmarsson et al., 2005, EPSL v. 234; Vlastelic et al., 2005, J. Petrol. v. 46) processes. Possible explanations for the data will be explored at the meeting.

Pietruszka, A. J.; Hauri, E. H.; Albarede, F.; Blichert-Toft, J.

2005-12-01

248

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

249

The evolution of ocean island volcanoes in a stationary plate environment and its implications concerning hotspot dynamics  

NASA Astrophysics Data System (ADS)

The evolution of oceanic hotspot systems is strongly influenced by plate velocity relative to the melting source, age/thickness of the lithosphere, proximity to a plate boundary, and melting source parameters. In fast-moving plates, volcanic loci move away from the melting source and an obvious mechanism for the waning of volcanism is established. A linear island chain is thus created and a distinct edifice evolutionary pattern is recognizable. This evolutionary pattern is strongly influenced by long-term subsidence created by flexural loading and hotspot swell decay with plate movement, albeit some small uplift when edifices cross the flexural bulge; the transition from island to guyot is essentially dictated by subsidence. Conversely, in stationary or quasi-stationary plate environments, edifices do not or barely move away from the melting source so other mechanisms must be accounted for the long-term decrease in volcanic activity and the different edifice evolution. The Cape Verde Archipelago is the type-example of a hotspot in an old, stiff plate that is stationary with respect to its melting source, making it an ideal place to study ocean island evolution and oceanic hotspot dynamics in a stationary plate environment. Observations in this archipelago suggest that island evolution in such geodynamic environments is generally characterized by long-term vertical stability or even pronounced uplift trends, prolonging the islands lifetime above sea-level; the transition from island to guyot is essentially dictated by marine erosion. Uplift reconstructions for the Cape Verde Archipelago - using dateable relative sea-level tracers such as lava deltas, submarine volcanic units and marine terraces - suggest that two processes have acted to raise the islands during their lifetime. During an initial phase, mantle processes acted to build the swell. Subsequently, magmatic intrusions in the island edifice caused up to 350 m of local uplift at the scale of individual islands and often synchronous with vigorous volcanic stages. Finally, swell-wide uplift contributed a further 100 m of surface rise. This recent swell-wide uplift is well expressed throughout the archipelago by means of Quaternary marine terraces up to ~100 m asl, even in islands without recent volcanism. These observations pose several constraints concerning oceanic hotspot dynamics: first, a seemingly episodic hotspot swell growth implies that the buoyancy source changes that act to raise the swell are probably cumulative, favoring a model that advocates for accumulation and spreading of depleted material leftover from partial melting; secondly, intrusive processes at hotspots in stationary plate environments are probably much more important than previously thought, and are the likely source of significant amounts of uplift; and thirdly, plate velocity relative to the melting source is expected to be a powerful constraint on intrusive vs extrusive processes of island building.

Ramalho, R.

2012-04-01

250

Tsunami deposits in Santiago Island (Cape Verde archipelago) as possible evidence of a massive flank failure of Fogos volcano  

Microsoft Academic Search

Massive flank failures of volcanic edifices generate tsunami waves. These low-frequency but high magnitude hazards remain poorly documented because of the scarcity of observations. Offshore deposits are studied only by geophysical surveys and the failure rheologies are poorly constrained. Marine conglomerates found at unusually high elevations in Hawaii and in the Canary Islands were previously interpreted as being the result

Raphaël Paris; Thomas Giachetti; Joël Chevalier; Hervé Guillou; Norbert Frank

2011-01-01

251

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)

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.

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

2013-05-01

252

Cascades Volcano Observatory - Learn About Volcanoes: Frequently Asked Volcano Questions  

NSDL National Science Digital Library

This page provides the answers to frequently asked questions about volcanoes. It is created by the United States Geological Survey. Topics addressed include: What Is A Volcano? Why Do Volcanoes Occur? How Do Volcanoes Erupt? Where Do Volcanoes Occur? When Will A Volcano Erupt? How Hot Is A Volcano? Can Lava Be Diverted? Do Volcanoes Affect Weather? What Types of Volcanoes are There? Which Eruptions Were The Deadliest? 20th Century Volcanic Eruptions and Their Impact. About 60 additional questions with answers are available under MORE FAQ's -Volcano Questions and Answers, and includes some sections on volcanoes of the western United States. Other links to volcano information are also available.

253

Electrical structure beneath the eastern collapsed flank of Piton de la Fournaise volcano, Reunion Island: Implications for the quest for groundwater  

NASA Astrophysics Data System (ADS)

Time domain electromagnetic (TDEM) and tensor audiomagnetotelluric (AMT) data have been acquired at several locations on the eastern flank of Piton de la Fournaise volcano (Reunion Island) within a depressed area called Grand Brulé, interpreted as a collapse structure. The survey objectives were (1) to provide a geophysical estimate of the subsurface structure and (2) to evaluate the possibility of detecting aquifers in a volcanic environment not very known. The TDEM and the AMT data collected along two E-W traverses orthogonal to coastline on the northern and southern edges of Grand Brulé were interpreted with one-dimensional layered models. From the surface downward, the geoelectrical sections reveal two major units: very resistive, young lava flows (dry) and a shallow conductor (<500 m) which is probably primarily attributable to a clayey, poorly permeable base. A notable exception to this pattern is seen at sites close to the coast, where we found three-layered structures. There is an intermediate layer of resistivity of about 100-200 ohm m between the top resistive layer and bottom conductive layer that represents a probable freshwater lens in the southern part and an alluvial fan with resistivities substantially higher (200 ohm m) in the northern part of Grand Brulé. It is suggested that the 200 ohm m layer, interpreted as a buried paleoriver, corresponds to a drainage structure.

Descloitres, Marc; Ritz, Michel; Robineau, Bernard; Courteaud, Michel

1997-01-01

254

Eruption Rate Control On Morphology And Structure Of Submarine Monogenetic Volcanoes - Insights From Sumersible Dives Off Maui And Hawaii Islands  

Microsoft Academic Search

This paper presents the results of submersible dives off Hawaii Islands during four research cruises (R\\/V Kairei-ROV Kaiko 1998 and 2001, R\\/V Yokosuka-DSV Shinkai 1999 and 2002) by the Japan Marine Science and Technology Center. Morphologies and structures of submarine volcanic edifices were observed during dives on the Hana Ridge, submarine extension of Haleakala rift zone of East Maui and

S. Umino

2003-01-01

255

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

256

Collapsing volcanoes  

Microsoft Academic Search

A series of studies has been conducted which examined Landsat images of volcanoes in the central Andes in order to identify previously unknown avalanche deposits, with attention to the Socompa volcano in Chile. The occasional, massive collapse of an unstable volcanic cone may be seen as a normal event in the life cycle of a volcano; this is especially true

Peter Francis; Stephen Self

1987-01-01

257

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

258

Fumarole-supported islands of biodiversity within a hyperarid, high-elevation landscape on Socompa Volcano, Puna de Atacama, Andes.  

PubMed

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 (13)C-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 (13)C-rich CO(2) 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

Costello, Elizabeth K; Halloy, Stephan R P; Reed, Sasha C; Sowell, Preston; Schmidt, Steven K

2008-12-12

259

Fumarole-Supported Islands of Biodiversity within a Hyperarid, High-Elevation Landscape on Socompa Volcano, Puna de Atacama, Andes? †  

PubMed Central

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.

Costello, Elizabeth K.; Halloy, Stephan R. P.; Reed, Sasha C.; Sowell, Preston; Schmidt, Steven K.

2009-01-01

260

Factors controlling the morphology of monogenetic basaltic volcanoes: The Holocene volcanism of Gran Canaria (Canary Islands, Spain)  

NASA Astrophysics Data System (ADS)

A detailed morphometric analysis was performed on the 24 Holocene eruptions of Gran Canaria, a nearly circular island located at the centre of the Canary Islands (Spain), developed as result of the eastward movement of the African plate over a mantle hotspot. Rigorous field work was carried out to generate a palaeogeomorphological reconstruction of the Holocene eruptions of Gran Canaria to obtain pre- and post-eruption digital terrain models (DTMs). These eruptions were of Strombolian monogenetic basaltic volcanism style. With respect to the cones, feeder fissures determine their location and some morphological features as crater openings which are usually perpendicular to the slope direction. In addition, the trade winds influence the final volcanic edifice shape and the extent of the pyroclastic sheet-like fall deposits. For the lava flows, the most significant controls are the eruption rate, affecting the maximum distance travelled, and the gully slope and shape that condition their flow path. Concerning volcanic hazard and risk assessment, the applied methodology has led to a better understanding of the recent eruptions and foresees the location and nature of future eruptions.

Rodriguez-Gonzalez, A.; Fernandez-Turiel, J. L.; Perez-Torrado, F. J.; Paris, R.; Gimeno, D.; Carracedo, J. C.; Aulinas, M.

2012-01-01

261

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

PubMed Central

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.

Villacorta, Carlos; Jaume, Damia; Oromi, Pedro; Juan, Carlos

2008-01-01

262

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

NASA Astrophysics Data System (ADS)

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

Yeguas, A. García.; Almendros, J.; Abella, R.; Ibáñez, J. M.

2011-02-01

263

Satellite monitoring of remote volcanoes improves study efforts in Alaska  

Microsoft Academic Search

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

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

1998-01-01

264

Living with Volcanoes: Year Eleven Teaching Resource Unit.  

ERIC Educational Resources Information Center

|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)|

Le Heron, Kiri; Andrews, Jill; Hooks, Stacey; Larnder, Michele; Le Heron, Richard

2000-01-01

265

Erupting Volcanoes!  

NSDL National Science Digital Library

This lesson presents volcanoes through the making of volcano models. While students are constructing their physical representations of volcanoes, they will be filled with questions about volcanoes as well as how to build their models. This process will provide students with a tangible reference for learning about volcanoes and give them a chance to problem-solve as they build their models. Students will be able to observe how the eruption changes the original form of their volcano model. In this way, students see first hand how this type of phenomenon creates physical change. While students at this level may struggle to understand larger and more abstract geographical concepts, they will work directly with material that will help them build a foundation for understanding concepts of phenomena that sculpt the Earth.

266

Schematic driven layout of Reed Solomon encoders  

NASA Astrophysics Data System (ADS)

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.

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

267

Volcano Types  

NSDL National Science Digital Library

This site lists the basic types of volcanoes: scoria cone, shield volcano, and stratovolcano. Each is described in terms of shape, composition, and eruption type, and links are available to additional information. Subordinate types listed include fissure eruptions, spatter cones, hornitos, and hydrovolcanic eruptions. The site also explains when a volcano is considered active, dormant, or extinct. In addition, generic features such as vent, central vent, edifice, magma chamber, parasitic cones, and fumaroles are listed and described.

Camp, Victor

268

Variability in Solomon Sea circulation derived from altimeter sea level data  

NASA Astrophysics Data System (ADS)

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.

Melet, Angélique; Gourdeau, Lionel; Verron, Jacques

2010-08-01

269

Hawaii Volcanoes and Volcanics - Maps and Graphics, etc.  

NSDL National Science Digital Library

This page provides maps, "pictograms", photographs, and graphics of the Hawaiian volcanoes. Maps include volcano locations in the Hawaiian Island chain, Hawaii Island, and Maui, and a global map of the 16 Decade Volcanoes, which include Mauna Loa. Photographs or "pictograms" demonstrate a shield volcano versus a composite volcano (Mauna Loa versus Mount Rainier, Washington) and Hawaiian-Style Eruptions vs. Cascades-Style Eruptions - Pu'u O'o, Hawaii vs. Mount St. Helens, Washington. The graphic shows the profile of Mauna Loa and Kilauea versus Mount Rainier.

270

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

271

Plant Diversity Changes during the Postglacial in East Asia: Insights from Forest Refugia on Halla Volcano, Jeju Island  

PubMed Central

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.

Dolezal, Jiri; Altman, Jan; Kopecky, Martin; Cerny, Tomas; Janecek, Stepan; Bartos, Michael; Petrik, Petr; Srutek, Miroslav; Leps, Jan; Song, Jong-Suk

2012-01-01

272

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

PubMed

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

Dolezal, Jiri; Altman, Jan; Kopecky, Martin; Cerny, Tomas; Janecek, Stepan; Bartos, Michael; Petrik, Petr; Srutek, Miroslav; Leps, Jan; Song, Jong-Suk

2012-03-16

273

Syn and posteruptive hazards of maar–diatreme volcanoes  

Microsoft Academic Search

Maar–diatreme volcanoes represent the second most common volcano type on continents and islands. This study presents a first review of syn- and posteruptive volcanic and related hazards and intends to stimulate future research in this field. Maar–diatreme volcanoes are phreatomagmatic monogenetic volcanoes. They may erupt explosively for days to 15 years. Above the preeruptive surface a relatively flat tephra ring forms.

Volker Lorenz

2007-01-01

274

Decade Volcanoes  

NSDL National Science Digital Library

In the 1990s, the International Association of Volcanology and Chemistry of the Earth's Interior started the Decade Volcano Project. As part of their work, they designated sixteen volcanoes particularly worthy of study "because of their explosive histories and close proximity to human populations." The group recently teamed up with National Geographic to create a guide to these volcanoes via this interactive map. Navigating through the map, visitors can learn about Mount Rainier, Colima, Galeras, Santorini, and other prominent volcanoes. For each volcano, there's a brief sketch that gives the date of its last eruption, its elevation, nearby population centers, and a photograph. Additionally, visitors can learn more by clicking on the sections titled "Did You Know?" and "Eruption Interactive".

2007-11-02

275

Volcano spacing and plate rigidity  

SciTech Connect

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.

Brink, U. (Stanford Univ., California (USA))

1991-04-01

276

Abramovite, Pb2SnInBiS7, a new mineral species from fumaroles of the Kudryavy volcano, Kurile Islands, Russia  

NASA Astrophysics Data System (ADS)

Abramovite, a new mineral species, has been found as fumarole crust on the Kudryavy volcano, Iturup Island, Kuriles, Russia. The mineral is associated with pyrrhotite, pyrite, würtzite, galena, halite, sylvite, and anhydrite. Abramovite occurs as tiny elongated lamellar crystals up to 1 mm long and 0.2 mm wide (average 300 × 50 ? m), which make up chaotic intergrowths in the narrow zone of fumarole crust formed at ˜600°C. Most crystals are slightly striated along the elongation. The new mineral is silver gray, with a metallic luster and black streak. Under reflected light, abramovite is white with a yellowish gray hue. It has weak bireflectance; anisotropy is distinct without color effects. The chemical composition (electron microprobe) is as follows, wt %: 20.66 S, 0.98 Se, 0.01 Cu, 0.03 Cd, 11.40 In, 12.11 Sn, 37.11 Pb, 17.30 Bi; the total is 99.60. The empirical formula calculated on the basis of 12 atoms is Pb1.92Sn1.09In1.06Bi0.89(S6.90Se0.13)7.03. The simplified formula is Pb2SnInBiS7. The strongest eight lines in the X-ray powder pattern [ d, Å ( I)( hkl)] are 5.90(36)(100), 3.90(100)(111), 3.84(71)(112), 3.166(26)(114), 2.921(33)(115), 2.902(16)(200), 2.329(15)(214), 2.186(18)(125). The selected area electron diffraction (SAED) patterns of abramovite are quite similar to those of the homologous cylindrite series minerals. The new mineral is characterized by noncommensurate structure composed of regularly alternated pseudotetragonal and pseudohexagonal sheets. The structure parameters determined from the SAED patterns and X-ray powder diffraction data for pseudotetragonal subcell are: a = 23.4(3), b = 5.77(2), c = 5.83(1) Å, ? = 89.1(5) °, ? = 89.9(7)°, ? = 91.5(7)°, V = 790(8) Å3; for pseudohexagonal subcell: a = 23.6(3), b = 3.6(1), c = 6.2(1) Å, ? = 91(2)°, ? = 92(1)°, ? = 90(2)°, V = 532(10) Å3. Abramovite is triclinic, space group P(1). The new mineral is named in honor of Russian mineralogist Dmitry Abramov. The type material of abramovite has been deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

Yudovskaya, M. A.; Trubkin, N. V.; Koporulina, E. V.; Belakovsky, D. I.; Mokhov, A. V.; Kuznetsova, M. V.; Golovanova, T. I.

2008-12-01

277

Large landslides from oceanic volcanoes  

Microsoft Academic Search

GLORIA sidescan sonar surveys have shown that large landslides are ubiquitous around the submarine flanks of Hawaiian volcanoes, and GLORIA has also revealed large landslides offshore from Tristan da Cunha and El Hierro. On both of the latter islands, steep flanks formerly attributed to tilting or marine erosion have been reinterpreted as landslide headwalls mantled by younger lava flows. Large

Robin T. Holcomb; Roger C. Searle

1991-01-01

278

Records of plant viruses for the Pacific Islands  

Microsoft Academic Search

This paper lists the known distribution of 57 plant viruses and viroids in the 22 Pacific Island countries covered by the\\u000a Secretariat of the Pacific Community (American Samoa, Cook Islands, FSM (Micronesia), Fiji, French Polynesia, Guam, Kiribati,\\u000a Marshall Islands, Nauru, New Caledonia, Niue, Northern Mariana Islands, Palau, Papua New Guinea, Pitcairn Islands, Solomon\\u000a Islands, Tokelau, Tonga, Tuvalu, Vanuatu, Wallis and

Michael N. Pearson; Michel Grisoni

2002-01-01

279

Collapsing volcanoes  

NASA Astrophysics Data System (ADS)

A series of studies has been conducted which examined Landsat images of volcanoes in the central Andes in order to identify previously unknown avalanche deposits, with attention to the Socompa volcano in Chile. The occasional, massive collapse of an unstable volcanic cone may be seen as a normal event in the life cycle of a volcano; this is especially true in the case of large 'stratovolcanoes', of which there are many hundreds in the 'Ring of Fire' around the Pacific rim. Stratovolcanoes are susceptible to collapse because of their association with subduction zones. Three kinds of collapse can be distinguished among stratovolcanoes.

Francis, Peter; Self, Stephen

1987-06-01

280

Model Volcanoes  

NSDL National Science Digital Library

In this lesson, students will explore volcanoes by constructing models and reflect upon their learning through drawing sketches of their models. Once they have finished making their models, they will experiment with making their volcanoes erupt. They will observe how eruption changes the original form of their volcano models. In this way, students see first hand how this type of phenomena creates physical change. While students at this level may struggle to understand larger and more abstract geographical concepts, they will work directly with material that will help them build a foundation for understanding concepts of phenomena that sculpt the earth.

281

Cascade Volcanoes  

USGS Multimedia Gallery

The volcanoes from closest to farthest are Mt. Washington, Three Fingered Jack, Mt. Jefferson. This picture is taken from Middle Sister looking north in the Cascade Range, Three Sisters Wilderness Area, Deschutes National Forest, Oregon....

2009-12-08

282

The LLWBCs of the Solomon Sea depicted by altimetry and gliders  

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

283

Globalization and the Island Economies of the South Pacific  

Microsoft Academic Search

This paper examines the impact of increasing integration of the island economies of the South Pacific into expanding international markets, particularly that of Fiji and the Solomon Islands. Since the 1980s, globalization of the world economy has altered dramatically the volume and character of international resource flow. This has provided small island economies financing for international transactions, competitiveness, and diffusion

Rukmani Gounder; V. Xayavong

2001-01-01

284

A magmatic source for fumaroles and diffuse degassing from the summit crater of Teide Volcano (Tenerife, Canary Islands): a geochemical evidence for the 2004-2005 seismic-volcanic crisis  

NASA Astrophysics Data System (ADS)

The present work reports the results of 15 studies of diffuse CO2 degassing performed at Teide Volcano crater (Canary Island, Spain) and the chemical and isotopic compositions of fluids discharged from a fumarolic field located at the top of the volcano as measured between 1991 and 2010. A higher contribution of magmatic gases accompanied by enhanced total diffuse CO2 emissions were observed in relation with a seismic crisis that occurred in Tenerife Island between 2001 and 2005, with the main peak of seismic activity between April and June 2004. A significant pulse in total diffuse CO2 emission was observed at the crater of Teide (up to 26.3 t day-1) in 2001. In December 2003, the chemical composition of the Teide fumarole changed significantly, including the appearance of SO2, an increase in the HCl and CO concentrations and in the C2H6/C2H4 and C3H8/C3H6 ratios, and a decrease in the H2S, CH4, and C6H6 concentrations and in the gas/steam ratio. A few months after a drastic decrease in seismic activity, the SO2, HCl, and CO concentrations and the C2H6/C2H4 and C3H8/C3H6 ratios strongly decreased, whereas the CH4 and C6H6 concentrations and the gas/steam ratios increased. According to the trends shown by both the geochemical parameters and the seismic signals late in the observation period, the risk of a rejuvenation of volcanic activity at Teide is considered to be low. The associated temporal changes in seismic activity and magmatic degassing indicate that geophysical and fluid geochemistry signals in this system are related. Future monitoring programs aimed at mitigating volcanic hazard on Tenerife Island should involve coupled geophysical and geochemical studies.

Melián, G.; Tassi, F.; Pérez, N.; Hernández, P.; Sortino, F.; Vaselli, O.; Padrón, E.; Nolasco, D.; Barrancos, J.; Padilla, G.; Rodríguez, F.; Dionis, S.; Calvo, D.; Notsu, K.; Sumino, H.

2012-08-01

285

Mahukona: The missing Hawaiian volcano  

SciTech Connect

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.

Garcia, M.O.; Muenow, D.W. (Univ. of Hawaii, Honolulu (USA)); Kurz, M.D. (Woods Hole Oceanographic Institution, MA (USA))

1990-11-01

286

Decoding Reed Solomon Codes beyond the Error-Correction Diameter  

Microsoft Academic Search

We describe a new algorithm for the decoding of Reed Solomon codes. This algorithmwas originally described in [12]. While the algorithm presented in this articleis the same, the presentation is somewhat different. In particular we derive moreprecise bounds on the performance of the algorithm and show the following: For an[n; n; (1 \\\\Gamma )n] q Reed Solomon code, the algorithm

Madhu Sudan

1997-01-01

287

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)

A Computerized Uniaxial Press working up to 250 kN was installed in the middle 2011 in the Laboratory of Microseismic Monitoring of ISEL. The system is able to record continuous time, pressure and axial strain (1 µm resolution) at 1s sampling rate. The loading platens were designed to integrate acoustic emission (AE) transducers. Signals are acquired and processed through an 8-channel ESG Hyperion Ultrasonic Monitoring System (10 MSPS, 14/16-bit ADC). The first experiments, presented here, were applied to a set of rock samples from the Fogo, an active central volcano in the island of Sao Miguel. Two different volcanic rock types were studied: a fine grained alkali basaltic rock with a porphyritic texture, a porosity of 4.5% and bulk density of 2700 kg m-3 (sample #3); and a benmoreitic rock with a trachytic texture, a porosity of 8.1 %, and bulk density of 2400 kg m-3 (sample #4). Cores from sample #3 were subjected to continuous increasing pressure, until failure. They show a uniaxial compressive strength (UCS) spanning from 60 to 85 MPa and a stress-strain curve with two phases: a first one with relative low Young's Module (YM) followed by a second phase were the YM increases roughly 3 times. The stress transition value occurs broadly in a stress level 50% of the UCS. The AE produced in the process is almost negligible until the YM transition stress level and increases after that. Important pulses of high AE rate occur, (> 100 s-1), associated with the occurrence and propagation of fractures, which are always parallel to the principal stress, showing an evident pattern of tensile fractures. About 20s before the failure, very important deformation rate is observed, the YM strongly decrease, and continuous AE events, with low rate, usually <50 s-1. The failure is accompanied with a sudden rise of AE events with rate > 200 s-1. Cycling stress experiences were also performed showing reversible stress-strain relation for axial pressure below the YM transition level, and important hysteresis for axial pressure above that level. The associated AE events show a characteristic Kaiser effect pattern. Cores from sample #4 undergo the same continuous increasing stress process, but failure is attained at a considerable lower pressure of 20-25 MPa. The stress-strain curves show an almost linear relation, but approaching the stress level of failure, the YM decreases. The AE events are constant but with a reduced rate until the decrease of the YM, when a significant rise in the AE occurs, achieving emission rates greater that 200 s-1. The fracture shows a characteristic shear pattern. Differences in stress-strain behavior, fracture mode and AE rates are associated with the very different structure of the rocks, once the basaltic sample is very fine grained with some very scattered and almost spherical vesicles or voids, while the benmoreitic core shows high values of porosity in a structure with vesicles and voids with very irregular shapes. Work supported by FCT, Portugal, projet FreeRock, PTDC/CTE-GIX/100687/2008

Moreira, M.; Wallenstein, N.

2012-04-01

288

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

Microsoft Academic Search

Volcanoes with crater lakes are often characterised by shallow hydrothermal systems which display cyclic behaviour (temperature, lake level, chemistry, etc.) and shallow seismic tremor. Present monitoring programmes in New Zealand include routine collection of these observables, but the associated shallow sub-surface processes are still inadequately modelled and poorly understood. Models would be better constrained with the incorporation of additional geophysical

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

2010-01-01

289

Spreading volcanoes  

USGS Publications Warehouse

As volcanoes grow, they become ever heavier. Unlike mountains exhumed by erosion of rocks that generally were lithified at depth, volcanoes typically are built of poorly consolidated rocks that may be further weakened by hydrothermal alteration. The substrates upon which volcanoes rest, moreover, are often sediments lithified by no more than the weight of the volcanic overburden. It is not surprising, therefore, that volcanic deformation includes-and in the long term is often dominated by-spreading motions that translate subsidence near volcanic summits to outward horizontal displacements around the flanks and peripheries. We review examples of volcanic spreading and go on to derive approximate expressions for the time volcanoes require to deform by spreading on weak substrates. We also demonstrate that shear stresses that drive low-angle thrust faulting from beneath volcanic constructs have maxima at volcanic peripheries, just where such faults are seen to emerge. Finally, we establish a theoretical basis for experimentally derived scalings that delineate volcanoes that spread from those that do not.

Borgia, A.; Delaney, P. T.; Denlinger, R. P.

2000-01-01

290

Paleogene stratigraphy of the Solomons Island, Maryland corehole  

USGS Publications Warehouse

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.

Gibson, Thomas G.; Bybell, Laurel M.

1994-01-01

291

Cascade Range Volcanoes: North to South  

NSDL National Science Digital Library

This page lists Cascades Range volcanoes of British Columbia, Washington State, Oregon, and California. The user can click on the volcano name to get information on the volcano and its vicinity including Current Activity; Background and Information; Current Hazards Report; Visit a Volcano; Maps, Graphics, and Images; Items of Interest; and Useful Links. The volcanoes include: Garibaldi Lake Volcano, Meager Mountain, and Mount Garibaldi in British Columbia; Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State: Mount Hood, Mount Jefferson, Three-Fingered Jack, Mount Washington, Belknap Shield Volcano, Three Sisters (North, Middle, South), Broken Top, Mount Bachelor, Pilot Butte, Lava Butte, Newberry Caldera, Diamond Peak, Mount Bailey, Mount Thielsen, Crater Lake, Mount Mazama, Wizard Island, and Mount McLoughlin in Oregon:, and Lava Beds, Medicine Lake Volcano, Glass Mountain (Medicine Lake, California), Black Butte, Mount Shasta, and Lassen Peak in California. Links are provided to more general pages on volcanoes in the three states and in Canada.

292

Volcano Baseball  

NSDL National Science Digital Library

In this game, learners are volcanoes that must complete several steps to erupt. Starting at home plate, learners draw cards until they have enough points to move to first base. This process repeats for each learner at each base, and each base demonstrates a different process in a volcano's eruption. The first learner to make it back to home plate erupts and is the winner. This is a good introduction to volcanoes. When learners set up a free account at Kinetic City, they can answer bonus questions at the end of the activity as a quick assessment. As a larger assessment, learners can complete the Smart Attack game after they've completed several activities.

Science, American A.

2009-01-01

293

The decoding of Reed-Solomon codes  

NASA Astrophysics Data System (ADS)

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.

McEliece, R. J.

1988-11-01

294

Mineralized microbes from Giggenbach submarine volcano  

Microsoft Academic Search

The Giggenbach submarine volcano, which forms part of the Kermadec active arc front, is located ?780 km NNE of the North Island of New Zealand. Samples collected from chimneys associated with seafloor hydrothermal vents on this volcano, at a depth of 160–180 m, contain silicified microbes and microbes entombed in reticular Fe-rich precipitates. The mineralized biota includes filamentous, rod-shaped, and

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

2008-01-01

295

Zeta potential estimation of volcanic rocks on 11 island arc-type volcanoes in Japan: Implication for the generation of local self-potential anomalies  

Microsoft Academic Search

From streaming potential measurements, we deduced the zeta potential of 73 volcanic rock samples collected in 11 volcanoes where self-potential (SP) surveys had also been conducted. Experiments with crushed rock samples and 0.001 mol\\/L NaCl solution showed a large variation in streaming potential coefficient, which ranged from ?2860 to 2280 mV\\/MPa (deduced zeta potential ranged from ?45.1 to 37.2 mV).

Koki Aizawa; Makoto Uyeshima; Kenji Nogami

2008-01-01

296

Volcano survey  

Microsoft Academic Search

SummaryA short review is made of the main means of investigation of eruption forecast, used in the few existing, accurately staffed volcanological observatories as well as during sporadic expeditions on active volcanoes, together with non-exhaustive data obtained during recent years (volcanoseismology, gravimetry, tiltmetry, geodetic measurements, magnetic and aeromagnetic surveys, chemistry of gas, waters and sublimates, geochemistry). Details of research performed

H. Tazieff

1966-01-01

297

Volcano-Tectonic Deformation at Taal Volcano, Philippines  

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

298

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

299

Volcano Instability and Dike Swarms Controlled by Local Stress Field  

Microsoft Academic Search

Hotspot volcanoes in the Hawaiian, Canary, and the Reunion islands have two or three directions of dominant rift zones, which are highly developed. Rift zones in those islands are normally underlain by a sequence of basalt flow units, and consist of dike swarms which are elongated to a specific direction (with several kilometers length). In oceanic volcanic islands(Kilauea, Mauna Loa,

O. Otaki; N. Fujii

2004-01-01

300

Mt. Erebus: A Surprising Volcano: Grades K-1: Illustrated Book  

NSDL National Science Digital Library

This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. Students read about the volcano in a simplified manner. The text is written at a kindergarten through grade one reading level. This version is a full-color PDF that can be printed, cut and folded to form a book. Each book contains color photographs and illustrations.

Fries-Gaither, Jessica

301

Eruptive and Transportation Processes During Caldera-Forming Eruptions of Sete Cidades Volcano, São Miguel, Azores  

Microsoft Academic Search

Sete Cidades volcano forms the Western part of the island of São Miguel, Azores, which is hosting three active trachytic central volcanoes (Sete Cidades, Fogo, Furnas). Volcanic activity in the archipelago exhibits a strong tectonic control and on São Miguel, the NW-SE trending basaltic Terceira Rift is intersecting the central volcanoes. All three have erupted since the settlement of the

U. Kueppers; M. G. Queiroz; J. M. Pacheco

2007-01-01

302

Mud Volcanoes Formation And Occurrence  

NASA Astrophysics Data System (ADS)

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". Model of buoyancy drive (by Brown, 1990). Brown's basic hypothesis is similar to Ivanov and Guliev and may be summarized briefly as follows: -in situations where rapid sedimentation is occurring mud may be driven to the surface by buoyancy forces due to bulk density contrasts between mud and overlying sediment cover. Such density contrasts may be simply the result of compaction -disequilibrium, but more importantly may be related to gas expansion when fluids are transported to shallower depths with lower pressure and temperature conditions. Synthetic model had been proposed by I.Lerche, E.Bagirov, I.Guliyev (1997). The model includes the following studies: The starting point of the mud volcanoes begins with the formation of a zone of decompaction as a consequence of a high rate of gas generation. The mud body starts to rise under buoyancy. The excess pressure inside the mud intrusion is less than in surrounding formation. As a result, fluid flow toward the body of mud volcanoes. The body of the mud volcanoes then grows, increasing the buoyancy forces, with further drive the mud. If the rate of gas generation more thôn gas flow, causing exsolving of gas to free-phase gas. If there are open faults and fractures which cross the body of mud volcanoes, then gas and mud can penetrate through the faults, and so from gryphons and salses on the surface. A mud volcanoes can be consider as a huge accumulation of gas, where as the oil is concentrated on the flanks of the mud body.

Guliyev, I. S.

2007-12-01

303

The Earthscope Plate Boundary Observatory Akutan Alaskan Volcano Network Installation  

Microsoft Academic Search

During June and July of 2005, the Plate Boundary Observatory (PBO) installed eight permanent GPS stations on Akutan Volcano, in the central Aleutian Islands of Alaska. PBO worked closely with the Alaska Volcano Observatory and the Magmatic Systems Site Selection working group to install stations with a spatial distribution to monitor and detect both short and long term volcanic deformation

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

2005-01-01

304

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)

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

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

2007-05-01

305

Volcano Explorer: Build A Virtual Volcano  

NSDL National Science Digital Library

This website allows you to build virtual volcanoes and model their eruptions by changing gas and viscosity levels. Interactive screens define vocabulary and explain volcanic activity of three common volcano categories.

306

The petrogenesis of island arc basalts from Gunung Slamet volcano, Indonesia: Trace element and sup 87 Sr/ sup 86 Sr constraints  

SciTech Connect

Selected major and trace elements, rare earth element (REE) and {sup 87}Sr/{sup 86}Sr data are presented for arc basalts from Gunung Slamet volcano, Java, Indonesia. On the basis of stratigraphy, trace element content, Zr/Nb, and {sup 87}Sr/{sup 86}Sr ratios, Slamet basalts can be broadly categorized into high abundance magma (HAM) and low abundance magma (LAM) types. Provided the quantities of immobile trace elements (in aqueous systems) such as Nb, Hf and Zr in the mantle wedge and ensuing magmas are unaffected by additions from subducted lithosphere or overlying arc crust, a model may be developed whereby LAM are generated by higher degrees of melting in the mantle wedge (13%) compared to HAM (7%). Hf/Nb or Zr/Nb ratio systematics indicate that prior to metasomatism by the underlying lithosphere, the Slamet mantle wedge was similar in chemical character to transitional-MORB source mantle.

Vukadinovic, D.; Nicholls, I.A. (Monash Univ., Victoria (Australia))

1989-09-01

307

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)

Piton de la Fournaise is a frequently active basaltic volcano with more than 30 fissure eruptions since 1998. These eruptions are always preceded by pre-eruptive swarms of volcano-tectonic earthquakes which accompany dike propagation. Occasionally, intrusion swarms occur without leading to any eruption. From October 2008 to May 2011, as part of the research project Undervolc, a temporary network of 15 broadband stations has been installed on the volcano to complement the local monitoring network. We examined in detail the 6 intrusive and 5 pre-eruptive swarms which occurred during the temporary experiment. All the crises lasted for a few hours and only included shallow events clustered below the summit craters, around and above sea level, showing no signs of deeper magma transfers. These characteristics are common to most swarms observed at Piton de la Fournaise arising questions about the origin of the seismicity which seems to be poorly linked with dike propagation. With the aim to identify the main seismogenic structures active during the swarms, we applied precise earthquake detection and classification techniques based on waveform cross-correlation. For each swarm, the onsets of all transients, including small amplitude ones, have been precisely detected at a single station by scanning the continuous data with reference waveforms. The classification of the detected transients indicates the presence of several families of similar earthquakes. The two main families (F01 and F02) include several hundred events. They are systematically activated at the beginning of each pre-eruptive swarm but are inactive during the intrusive ones. They group more than 50 percent of the detected events for the corresponding crises. The other clusters are mostly associated with single swarms. To determine the spatial characteristics of the structures corresponding to the main families, we applied precise relocation techniques. Based on the one-station classification, the events have first been picked at all available stations by cross-correlating waveforms with those of master events whose arrival times have been manually determined. All events have been located using a 3D velocity model to determine accurate hypocentral azimuths and take-off angles. Precise relative locations have been computed for each multiplet using cross-correlation delays calculated for all available stations between all pairs of events. The results indicate the presence at sea level of a major structure grouping families F01 and F02 and describing an East-West elongated pattern with sub-vertical extension. Small scale earthquake migrations, mostly horizontal, occur during the pre-eruptive swarms along that structure. The smaller multiplets define vertically elongated patterns extending around and above the main F01-F02 multiplet. Our results show that different processes are involved in pre-eruptive and intrusive crises and that a structure located around 2.5 km below the summit controls the occurrence of recent eruptions of Piton de la Fournaise volcano.

Battaglia, J.; Brenguier, F.

2011-12-01

308

New K-Ar ages and the geologic evidence against rejuvenated-stage volcanism at Haleakala??, East Maui, a postshield-stage volcano of the Hawaiian island chain  

USGS Publications Warehouse

The postshield and previously inferred rejuvenated-stage history of Haleakala?? volcano is reevaluated on the basis of 52 new K-Ar ages, 42 from the postshield Kula Volcanics and 10 from the overlying Ha??na Volcanics. Postshield extrusion was robust from 0.93 to 0.76 Ma. A period of low extrusion rate or volcanic quiescence occurred between 0.76 and 0.65 Ma, well within Kula time. A chemical change to increasingly alkalic lava occurred at this time as the volcano changed from broadly hawaiitic to basanitic in its eruptive products and robust extrusion resumed. A slightly longer period of low extrusion rate or quiescence occurred after ca. 0.4 Ma, but only trifling change in geochemical character is observed. Geochemically, the Ha??na Volcanics unit, chiefly basanitic, overlaps greatly with the upper part of the Kula Volcanics; there is a weak tendency to slightly more alkaline character among the Ha??na Volcanics. The age of the Kula/Ha??na boundary is ca. 0.15-0.12 Ma; thus, volcanic quiescence of only ???0.03 m.y. separates the two formations, much shorter than the previously known limit of 0.25-0.30 m.y. The brevity of this hiatus, coupled with coincident vent loci and broadly similar geochemical characteristics for the Ha??na and the upper part of the Kula Volcanics, indicates that the Ha??na Volcanics unit comprises deposits of postshield-stage volcanism that has waned substantially since ca. 0.4-0.3 Ma. Haleakala?? has not yet begun a classically defined rejuvenated stage. Our findings support recent numerical modeling of plume-lithosphere interactions that predict that Haleakala?? is near the end of its postshield growth.

Sherrod, D. R.; Nishimitsu, Y.; Tagami, T.

2003-01-01

309

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

NASA Astrophysics Data System (ADS)

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

La Felice, Sonia; Landi, Patrizia

2011-11-01

310

Volcano Lovers  

NSDL National Science Digital Library

This Why Files article explores volcanoes and volcanic eruptions. Topics covered include: Alaska's Pavlof and its threat to jet engines; Mexico City's restless neighbor, Popocatepetl (El Popo); underground volcanic processes; modern forecasting of eruptions; various volcanic phenomena and features; large flood basalt areas around the world; California's volcanically active area, Long Valley Caldera and Mammoth Mountain; Indonesia's Krakatau eruption in 1883, which was the world's largest historical eruption; Krakatau's ecological contribution to the study of colonization of sterile lands; and central Mexico's Paricutin which was witnessed emerging from a farmer's field in 1943. Three scientists were interviewed for this article.

Tenenbaum, David

1997-01-02

311

Newberry Volcano—Central Oregon's Sleeping Giant  

USGS Publications Warehouse

Hidden in plain sight, Oregon's massive Newberry Volcano is the largest volcano in the Cascades volcanic arc and covers an area the size of Rhode Island. Unlike familiar cone-shaped Cascades volcanoes, Newberry was built into the shape of a broad shield by repeated eruptions over 400,000 years. About 75,000 years ago a major explosion and collapse event created a large volcanic depression (caldera) at its summit. Newberry last erupted about 1,300 years ago, and present-day hot springs and geologically young lava flows indicate that it could reawaken at any time. Because of its proximity to nearby communities, frequency and size of past eruptions, and geologic youthfulness, U.S. Geological Survey scientists are working to better understand volcanic activity at Newberry and closely monitor the volcano for signs of unrest.

Donnelly-Nolan, Julie M.; Stovall, Wendy K.; Ramsey, David W.; Ewert, John W.; Jensen, Robert A.

2011-01-01

312

The Electronic Volcano  

NSDL National Science Digital Library

The Electronic Volcano offers links to many types of information on active volcanoes, such as maps, photographs, full texts of dissertations and a few elusive documents. The Electronic Volcano will guide you to resources in libraries or resources on other information servers including catalogs of active volcanoes, datasets for literature citations, electronic and hard-copy journals, visual information, maps, observatories and institutions, and a volcano name and country index.

313

Earth Layers and Volcanoes  

NSDL National Science Digital Library

Why do we have volcanoes? Use the information on the websites to answer the questions on the worksheet. Worksheet First, review the layers of the earth. Labeling the layers game Next, go through the maze and read the information given. Magic School Bus volcano game Now, study the different shapes of volcanoes. Click enter, then volcano types in the menu. Read about the 3 types of volcanoes. Discovery Kids Games Finally, watch ...

Brookeshallow

2011-04-13

314

Geology of the Cook Islands  

Microsoft Academic Search

The geology of the 15 Cook Islands in the south-central Pacific is briefly described and their geological history outlined. All are the summit portions of extinct Tertiary volcanoes; six of the seven Northern Group islands are atolls, four of the Southern Group are makatea-type islands, and the others include a high mountainous volcanic island, a hilly near-atoll, an atoll, and

B. L. Wood

1967-01-01

315

Exploiting the cannibalistic traits of Reed-Solomon codes  

NASA Astrophysics Data System (ADS)

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

Collins, O.

1993-08-01

316

Rates of sulfur dioxide and particle emissions from White Island volcano, New Zealand, and an estimate of the total flux of major gaseous species  

Microsoft Academic Search

Airborne correlation spectrometry (COSPEC) was used to measure the rate of SO2 emission at White Island on three dates, i.e., November 1983, 1230 ± 300 t\\/d; November 1984, 320 ± 120 t\\/d; and January 1985, 350 ± 150 t\\/d (t = metric tons). The lower emission rates are likely to reflect the long-term emission rates, whereas the November 1983 rate

William I. Rose; Raymond L. Chuan; Werner F. Giggenbach; Philip R. Kyle; Robert B. Symonds

1986-01-01

317

Rifting, recurrent landsliding and Miocene structural reorganization on NW-Tenerife (Canary Islands)  

Microsoft Academic Search

We studied mechanisms of structural destabilization of ocean island flanks by considering the linkage between volcano construction and volcano destruction, exemplified by the composite Teno shield volcano on Tenerife (Canary Islands). During growth, Tenerife episodically experienced giant landslides, genetically associated with rifting and preferentially located between two arms of a three-armed rift system. The deeply eroded late Miocene Teno massif

T. Walter; H.-U. Schmincke

2002-01-01

318

Super Volcano  

NSDL National Science Digital Library

Deep beneath the surface of Earth lies one of the most destructive and yet least understood of the natural forces on the planet: the super volcano. This radio broadcast presents discussions with scientists at Yellowstone National Park who are investigating this potentially devastating natural phenomenon. Yellowstone National Park is one of the largest supervolcanoes in the world. It last erupted 640,000 years ago and scientists are now predicting that the next eruption may not be far off. To discover more, a new volcanic observatory has been built in the park to monitor the extreme volcanic activity going on beneath the surface of this much visited destination. The broadcast is 30 minutes in length.

319

Solomon as Philosopher King? The Nexus of Law and Wisdom in 1 Kings 1-11  

Microsoft Academic Search

Perhaps no other king in biblical literature has generated as much controversy as Solomon. On the one hand, we are told that 'Solomon's wisdom surpassed the wisdom of all the people of the East'; on the other hand, we are told that Solomon, in direct contravention to Israelite law, instituted slave labour, married many foreign women, and had shrines built

K. I. Parker

1992-01-01

320

Types of Volcanoes  

NSDL National Science Digital Library

This volcano resource introduces the six-type classification system and points out weaknesses of the classic three-type system. The six types of volcanoes are shield volcanoes, strato volcanoes, rhyolite caldera complexes, monogenetic fields, flood basalts, and mid-ocean ridges. For each type of volcano there is a description of both structure and dynamics along with examples of each. You can account for more than ninty percent of all volcanoes with these six types. Additionally, any system will be more useful if you use modifiers from the other potential classification schemes with the morphological types.

321

Volcanoes, Tsunamis and the demise of the Minoans  

Microsoft Academic Search

There is considerable evidence from archaeological sites on the Greek Islands of extensive volcanic activity. The most famous example is the eruption of the island volcano of Thera (Santorini) which buried the Minoan town of Akrotiri on Thera and may have played a significant role in the replacement of the Minoan civilization on Crete by the Myceneans. The eruption of

J. J. Monaghan; P. J. Bicknell; R. J. Humble

1994-01-01

322

Tephra compositions from Late Quaternary volcanoes around the Antarctic Peninsula  

NASA Astrophysics Data System (ADS)

Crustal extension and rifting processes opened the Bransfield Strait between the South Shetland Islands and the Antarctic Peninsula during the last 4 Ma. Similar processes on the Peninsula's eastern side are responsible for volcanism along Larsen Rift. There are at least 11 volcanic centers with known or suspected Late Pleistocene / Holocene explosive activity (Fig. 1). Fieldwork was carried out on the islands Deception, Penguin, Bridgeman and Paulet, moreover at Melville Peak (King George Is.) and Rezen Peak (Livingston Is.). Of special importance is the second ever reported visit and sampling at Sail Rock, and the work on never before visited outcrops on the northern slopes and at the summit of Cape Purvis volcano (Fig. 1). The new bulk tephra ICP-MS geochemical data provide a reliable framework to distinguish the individual volcanic centers from each other. According to their Mg-number, Melville Peak and Penguin Island represent the most primitive magma source. Nb/Y ratios higher than 0.67 in combination with elevated Th/Yb and Ta/Yb ratios and strongly enriched LREE seem to be diagnostic to distinguish the volcanoes located along the Larsen Rift from those associated with Bransfield Rift. Sr/Y ratios discriminate between the individual Larsen Rift volcanoes, Paulet Island showing considerably higher values than Cape Purvis volcano. Along Bransfield Rift, Bridgeman Island and Melville Peak have notably lower Nb/Y and much higher Th/Nb than Deception Island, Penguin Island and Sail Rock. The latter displays almost double the Th/Yb ratio as compared to Deception Island, and also much higher LREE enrichment but extraordinarily low Ba/Th, discriminating it from Penguin Island. Such extremely low Ba/Th ratios are also typical for Melville Peak, but for none of the other volcanoes. Penguin Island has almost double the Ba/Th and Sr/Y ratios higher than any other investigated volcano. Whereas the volcanoes located in the northern part of Bransfield Strait have Zr/Hf ratios lower than N-MORB, all other volcanoes including the Larsen Rift centers display Zr/Hf higher than N-MORB. It is expected that the correlation of the new data with published data from tephra layers found in ice, lake and marine sediment cores will contribute to a better constrained timing of individual climatic events identified in the northern Antarctic Peninsula area. Late Quaternary volcanoes around the northern Antarctic Peninsula.

Kraus, S.

2009-12-01

323

Volcanoes: Annenberg Media Project  

NSDL National Science Digital Library

Volcanoes is an exhibit from the Annenberg Media Project that provides a wealth of information about volcanoes and includes sections such as Melting Rocks, the Dynamic Earth, and Forecasting. Interactive exercises enable the user to learn how rock turns into magma, how to locate volcanoes, and how to decide if building a project near a volcano is safe. Quicktime videos are used for each of the six categories to illustrate the points outlined in the text.

1997-01-01

324

A volcano bursting at the seams: Inflation, faulting, and eruption at Sierra Negra volcano, Galápagos  

Microsoft Academic Search

The results of geodetic monitoring since 2002 at Sierra Negra volcano in the Galápagos Islands show that the filling and pressurization of an ˜2-km-deep sill eventually led to an eruption that began on 22 October 2005. Continuous global positioning system (CGPS) monitoring measured >2 m of accelerating inflation leading up to the eruption and contributed to nearly 5 m of

William W. Chadwick Jr.; Dennis J. Geist; Sigurjón Jónsson; Michael Poland; Daniel J. Johnson; Charles M. Meertens

2006-01-01

325

On deep holes of standard Reed-Solomon codes  

NASA Astrophysics Data System (ADS)

Determining deep holes is an important open problem in decoding Reed-Solomon codes. It is well known that the received word is trivially a deep hole if the degree of its Lagrange interpolation polynomial equals the dimension of the Reed-Solomon code. For the standard Reed-Solomon codes $[p-1, k]_p$ with $p$ a prime, Cheng and Murray conjectured in 2007 that there is no other deep holes except the trivial ones. In this paper, we show that this conjecture is not true. In fact, we find a new class of deep holes for standard Reed-Solomon codes $[q-1, k]_q$ with $q$ a prime power of $p$. Let $q \\geq 4$ and $2 \\leq k\\leq q-2$. We show that the received word $u$ is a deep hole if its Lagrange interpolation polynomial is the sum of monomial of degree $q-2$ and a polynomial of degree at most $k-1$. So there are at least $2(q-1)q^k$ deep holes if $k \\leq q-3$.

Wu, RongJun; Hong, ShaoFang

2012-12-01

326

VLSI array architecture for Reed-Solomon decoding  

Microsoft Academic Search

A new architecture is presented for solving a key equation in a Reed-Solomon decoder. This consists of an array of identical cells. The number of cells can be set to meet a given throughput specification. The architecture is briefly compared with other published systolic architectures for the same problem and its advantages and disadvantages are illustrated

B. Arambepola; S. Choomchuay

1991-01-01

327

Variability In The Solomon Sea From Altimetric Sea Level Data  

Microsoft Academic Search

In the southwest tropical Pacific, subtropical waters from the SEC flow in the Solomon Sea, mainly through the western boundary New Guinea Coastal Undercurrent, and join the equatorial western Pacific by three narrow straits. The NGCU transports part of the spiciness anomalies generated in the South East Pacific and subducted in the thermocline. Because the NGCU is a primary source

A. Melet; L. Gourdeau; W. Kessler; J. Verron

2007-01-01

328

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

ERIC Educational Resources Information Center

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

Tidey, Ashley

2000-01-01

329

Selecting the Most Efficient Reed Solomon Codes to Eliminate Jamming.  

National Technical Information Service (NTIS)

Reed-Solomon (RS) codes are, perhaps, the most widely applied channel codes in practice due to its ability to detect and correct random and burst errors. In today's military combat environment, the ability to communicate determines who wins or losses. For...

H. Benjamin

1999-01-01

330

Aerosol Lesson: Volcano Types  

NSDL National Science Digital Library

This activity has students research a list of volcanoes and then write detailed information they researched under a column that identifies that type of volcano - Cinder Cone, Composite, or Shield. Included are a worksheet and a collection of links to referential websites about specific volcanoes.

331

Where are the Volcanoes?  

NSDL National Science Digital Library

This formative assessment item discusses common misconceptions about volcano location around the world. Resources include background and content information as well as alignment to the National Science Education Standards. The probe could easily be modified to be used with a study of earthquakes instead of volcanoes. Teachers can access other resources including facts about volcanoes and lesson ideas.

Fries-Gaither, Jessica

332

The Volcano Adventure Guide  

Microsoft Academic Search

Adventure travels to volcanoes offer chance encounters with danger, excitement, and romance, plus opportunities to experience scientific enlightenment and culture. To witness a violently erupting volcano and its resulting impacts on landscape, climate, and humanity is a powerful personal encounter with gigantic planetary forces. To study volcano processes and products during eruptions is to walk in the footsteps of Pliny

Fraser Goff

2005-01-01

333

A Scientific Excursion: Volcanoes.  

ERIC Educational Resources Information Center

|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)|

Olds, Henry, Jr.

1983-01-01

334

How Volcanoes Work  

NSDL National Science Digital Library

This educational resource describes the science behind volcanoes and volcanic processes. Topics include volcanic environments, volcano landforms, eruption dynamics, eruption products, eruption types, historical eruptions, and planetary volcanism. There are two animations, over 250 images, eight interactive tests, and a volcano crossword puzzle.

2011-04-18

335

Focus: alien volcanos  

NASA Astrophysics Data System (ADS)

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.

Carroll, Michael; Lopes, Rosaly

2007-03-01

336

A precision tidal model for Montserrat (B.W.I) and insights on volcano-aquifer dynamics for the July 29, 2008 eruption at Soufrière Hills volcano  

Microsoft Academic Search

The ongoing eruption of the Soufrière Hills volcano (SHV), Montserrat, provides an unprecedented opportunity to study complex processes at an active andesitic arc volcano. There is for example evidence from geodetic measurements that volcanic activity follows a cyclic pattern. At the same time, geodetic signals on a small island such as Montserrat are prone to be affected by tidal artefacts,

Joachim Gottsmann; Michel van Camp; Nicolas Fournier

2010-01-01

337

Cascades Volcano Observatory  

NSDL National Science Digital Library

This is the homepage of the United States Geological Survey's (USGS) Cascades Volcano Observatory (CVO). The site features news and events, updates on current activity of Cascade Range volcanoes, and information summaries on each of the volcanoes in the range. There are also hazard assessment reports, maps, and a 'Living with Volcanoes' feature that provides general interest information. A set of menus provides access to more technical information, such as a glossary, information on volcano hydrology, monitoring information, a photo archive, and information on CVO research projects.

2010-09-15

338

Potential landslide activity affecting the archaeological site of Orongo (Easter Island-Chile): preliminary analysis  

Microsoft Academic Search

Easter Island forms part of the Easter Line, a continuous latitudinal chain of volcanic seamounts and islands in the Pacific Sea. The island's roughly triangular shape is determined by the merging of lava flows produced by its three main volcanoes (Rano Kau, Terevaka, Poike) which form its main mass. The Rano Kau volcano, sited in the SW vertex of the

C. Margottini; G. Delmonaco; D. Spizzichino; O. Pandolfi; R. Crisostomo; S. Nohe

2009-01-01

339

Roving the Pacific: Pacific Manuscripts Bureau Microfilming in the Pacific Islands.  

ERIC Educational Resources Information Center

Provides an overview of microfilming by the Pacific Manuscripts Bureau (PMB), a non-profit organization established in 1968 to identify and preserve archives, manuscripts, and rare printed documents relating to the South Pacific Islands. Describes a 1997 PMB microfilming expedition to Papua New Guinea and the Solomon Islands. (PEN)

Maidment, Ewan

1998-01-01

340

Roving the Pacific: Pacific Manuscripts Bureau Microfilming in the Pacific Islands.  

ERIC Educational Resources Information Center

|Provides an overview of microfilming by the Pacific Manuscripts Bureau (PMB), a non-profit organization established in 1968 to identify and preserve archives, manuscripts, and rare printed documents relating to the South Pacific Islands. Describes a 1997 PMB microfilming expedition to Papua New Guinea and the Solomon Islands. (PEN)|

Maidment, Ewan

1998-01-01

341

Volcanic geology of Furnas Volcano, São Miguel, Azores  

Microsoft Academic Search

Furnas is the easternmost of the three active central volcanoes on the island of São Miguel in the Azores. Unlike the other two central volcanoes, Sete Cidades and Fogo, Furnas does not have a well-developed edifice, but consists of a steep-sided caldera complex 8×5 km across. It is built on the outer flanks of the Povoação\\/Nordeste lava complex that forms

J. E Guest; J. L Gaspar; P. D Cole; G Queiroz; A. M Duncan; N Wallenstein; T Ferreira; J.-M Pacheco

1999-01-01

342

Sulphur output and magma degassing budget of Stromboli volcano  

Microsoft Academic Search

STROMBOLI volcano in the Aeolian islands has been erupting continuously for more than 2,000 years1, and probably as many as 5,000, following a major flank collapse2,3. Here we describe air-borne measurements of the plume flux of SO2 during 1980-93, which show that the volcano emits very large amounts of gas, mostly by open-conduit degassing between explosive outbursts, while exuding little

P. Allard; J. Carbonnelle; N. Métrich; H. Loyer; P. Zettwoog

1994-01-01

343

Mt. Erebus: A Surprising Volcano: Grades K-1: Electronic Book  

NSDL National Science Digital Library

This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. The text is written at a kindergarten through grade one reading level. This is an onscreen version that contains recorded narration allowing students to listen to the text as they read along. Highlighted vocabulary words have individually recorded definitions heard by clicking on the links.

Fries-Gaither, Jessica

344

Mafic Plinian volcanism and ignimbrite emplacement at Tofua volcano, Tonga  

Microsoft Academic Search

Tofua Island is the largest emergent mafic volcano within the Tofua arc, Tonga, southwest Pacific. The volcano is dominated\\u000a by a distinctive caldera averaging 4 km in diameter, containing a freshwater lake in the south and east. The latest paroxysmal\\u000a (VEI 5–6) explosive volcanism includes two phases of activity, each emplacing a high-grade ignimbrite. The products are basaltic\\u000a andesites with between

J. T. Caulfield; S. J. Cronin; S. P. Turner; L. B. Cooper

345

Glaciation of Haleakala volcano, Hawaii  

SciTech Connect

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.

Moore, J.G.; Mark, R. (Geological Survey, Menlo Park, CA (United States)); Porter, S.C. (Univ. of Washington, Seattle, WA (United States). Quaternary Research Center)

1993-04-01

346

The Anatahan volcano-monitoring system  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

347

Volcano Seismology  

NASA Astrophysics Data System (ADS)

- A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with wide dynamic range, and development of new powerful analysis techniques, rapid progress is being made toward a synthesis of high-quality seismic data to develop a coherent model of eruption mechanics. Examples of recent advances are: (1) high-resolution tomography to image subsurface volcanic structures at scales of a few hundred meters; (2) use of small-aperture seismic antennas to map the spatio-temporal properties of long-period (LP) seismicity; (3) moment tensor inversions of very-long-period (VLP) data to derive the source geometry and mass-transport budget of magmatic fluids; (4) spectral analyses of LP events to determine the acoustic properties of magmatic and associated hydrothermal fluids; and (5) experimental modeling of the source dynamics of volcanic tremor. These promising advances provide new insights into the mechanical properties of volcanic fluids and subvolcanic mass-transport dynamics. As new seismic methods refine our understanding of seismic sources, and geochemical methods better constrain mass balance and magma behavior, we face new challenges in elucidating the physico-chemical processes that cause volcanic unrest and its seismic and gas-discharge manifestations. Much work remains to be done toward a synthesis of seismological, geochemical, and petrological observations into an integrated model of volcanic behavior. Future important goals must include: (1) interpreting the key types of magma movement, degassing and boiling events that produce characteristic seismic phenomena; (2) characterizing multiphase fluids in subvolcanic regimes and determining their physical and chemical properties; and (3) quantitatively understanding multiphase fluid flow behavior under dynamic volcanic conditions. To realize these goals, not only must we learn how to translate seismic observations into quantitative information about fluid dynamics, but we also must determine the underlying physics that governs vesiculation, fragmentation, and the collapse of bubble-rich suspensions to form separate melt and vapor. Refined understanding of such processes-essential for quantitative short-term eruption forecasts-will require multidisciplinary research involving detailed field measurements, laboratory experiments, and numerical modeling.

Chouet, B.

348

Volcanoes: Nature's Caldrons Challenge Geochemists.  

ERIC Educational Resources Information Center

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

Zurer, Pamela S.

1984-01-01

349

Volcanoes: Nature's Caldrons Challenge Geochemists.  

ERIC Educational Resources Information Center

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

Zurer, Pamela S.

1984-01-01

350

Community preparedness for lava flows from Mauna Loa and Hualalai volcanoes, Kona, Hawai‘i  

Microsoft Academic Search

Lava flows from Mauna Loa and Hual?lai volcanoes are a major volcanic hazard that could impact the western portion of the island of Hawai‘i (e.g., Kona). The most recent eruptions of these two volcanoes to affect Kona occurred in a.d. 1950 and ca. 1800, respectively. In contrast, in eastern Hawai‘i, eruptions of neighboring K?lauea volcano have occurred frequently since 1955,

Chris E. Gregg; Bruce F. Houghton; Douglas Paton; Donald A. Swanson; David M. Johnston

2004-01-01

351

Growth and collapse of Waianae Volcano, Hawaii, as revealed by exploration of its submarine flanks  

Microsoft Academic Search

Wai‘anae Volcano comprises the western half of O‘ahu Island, but until recently little was known about the submarine portion of this volcano. Seven new submersible dives, conducted in 2001 and 2002, and multibeam bathymetry offshore of Wai‘anae provide evidence pertaining to the overall growth of the volcano's edifice as well as the timing of collapses that formed the Wai‘anae slump

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

2004-01-01

352

Growth and collapse of Waianae Volcano, Hawaii, as revealed by exploration of its submarine flanks  

Microsoft Academic Search

Wai`anae Volcano comprises the western half of O`ahu Island, but until recently little was known about the submarine portion of this volcano. Seven new submersible dives, conducted in 2001 and 2002, and multibeam bathymetry offshore of Wai`anae provide evidence pertaining to the overall growth of the volcano's edifice as well as the timing of collapses that formed the Wai`anae slump

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

2004-01-01

353

Volcanoes of North America  

NASA Astrophysics Data System (ADS)

Volcanoes of North America capitalises on the vast body of volcano literature now available to present, in a single source, detailed information about volcanoes found in North America. It contains brief accounts, written by leading experts in volcanology, of over 250 volcanoes and volcanic fields formed during the last 5 million years. The volcanoes of the continental United States, Alaska, Hawaii, and Canada are described. The precise location of each volcano is given, and the volcano is classified by type. Information about composition and eruptive history is also included. Each narrative description is accompanied by a photograph, a map of each location, and an extremely helpful statement on how to reach each volcano. The entries are mostly written at a level understandable by lay readers, but technical terms are also used and a background in geology is advantageous. Volcanoes of North America will be a standard reference work for practising volcanologists, petrologists, and geochemists, and to some extent, geographers. In addition, the maps and the 'How to get there' sections make this a highly valuable book for anyone interested in natural history or fascinated by volcanoes.

Wood, Charles Arthur; Kienle, Jürgen

1992-11-01

354

Algebraic soft-decision decoding of Reed-Solomon codes  

Microsoft Academic Search

A polynomial-time soft-decision decoding algorithm for Reed-Solomon codes is developed. This list-decoding algorithm is algebraic in nature and builds upon the interpolation procedure proposed by Guruswami and Sudan(see ibid., vol.45, p.1757-67, Sept. 1999) for hard-decision decoding. Algebraic soft-decision decoding is achieved by means of converting the probabilistic reliability information into a set of interpolation points, along with their multiplicities. The

Ralf Koetter; Alexander Vardy

2003-01-01

355

Symbol-Based Belief Propagation Decoding of Reed Solomon Codes  

Microsoft Academic Search

We propose a symbol-based belief propagation (BP) algorithm for iterative soft-decision decoding of Reed-Solomon (RS) codes. Complexity reduction is achieved by using a fast Fourier transform (FFT)-based BP algorithm. Parity-check matrix adaptation based on the reliability of the codeword symbols is an essential step to make the BP algorithm effective on high-density parity-check matrices characteristic of RS codes. The matrix

C. Zhong; J. R. Cruz

2009-01-01

356

Galactic Super Volcano Similar to Iceland Volcano  

NASA Video Gallery

This composite image from NASAs Chandra X-ray Observatory with radio data from the Very Large Array shows a cosmic volcano being driven by a black hole in the center of the M87 galaxy. This eruption is pumping energy into the black hole's surroundings and preventing hundreds of millions of new stars from forming just as the volcano in Iceland caused disruptions in the Earth's atmosphere.

Jim Wilson

2010-08-27

357

Seismo-acoustics, VLP and ULP signals, and other comparisons of surface broadband and CALIPSO borehole data at Soufriere Hills Volcano, Montserrat, B.W.I  

Microsoft Academic Search

Project CALIPSO (Caribbean Andesite Lava Island-volcano Precision Seismo-geodetic Observatory) investigates with borehole and surface instruments the magmatic system at the very active Soufriere Hills Volcano (SHV), Montserrat, supplementing surface monitoring systems of the Montserrat Volcano Observatory, and those of other institutions including PSU and U Ark. Many aspects of andesitic magmatic system dynamics remain little understood despite significant monitoring and

D. Hidayat; B. Voight; G. Mattioli; S. R. Young; A. T. Linde; I. S. Sacks; P. E. Malin; E. Shalev; D. Elsworth; C. Widiwijayanti; R. Herd; G. Thompson; V. Bass

2003-01-01

358

Prototype PBO Instrumentation of CALIPSO Project Captures World-Record Lava Dome Collapse on Montserrat Volcano  

Microsoft Academic Search

This article is an update on the status of an innovative new project designed to enhance generally our understanding of andesitic volcano eruption dynamics and, specifically, the monitoring and scientific infrastructure at the active Soufriàre Hills Volcano (SHV), Montserrat. The project has been designated as the Caribbean Andesite Lava Island Precision Seismo-geodetic Observatory, known as CALIPSO. Its purpose is to

Glen S. Mattioli; Simon R. Young; Barry Voight; R. Steven J. Sparks; Eylon Shalev; Sacks Selwyn; Peter Malin; Alan Linde; William Johnston; Dannie Hadayat; Derek Elsworth; Peter Dunkley; Richard Herd; Jurgen Neuberg; Gillian Norton; Christina Widiwijayanti

2004-01-01

359

Mt. Erebus: A Surprising Volcano: Grades K-1: text only version  

NSDL National Science Digital Library

This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. The reading level is at Kindergarten through grade one. This is a PDF containing the informational text and a glossary.

Fries-Gaither, Jessica

360

Coastal lava flows from Mauna Loa and Hualalai volcanoes, Kona, Hawaii  

Microsoft Academic Search

A major carbonate reef which drowned 13 ka is now submerged 150 m below sea level on the west coast of the island of Hawaii. A 25-km span of this reef was investigated using the submersibleMakali'i. The reef occurs on the flanks of two active volcanoes, Mauna Loa and Hualalai, and the lavas from both volcanoes both underlie and overlie

James G. Moore; David Clague

1987-01-01

361

Postshield volcanism and catastrophic mass wasting of the Waianae Volcano, Oahu, Hawaii  

Microsoft Academic Search

The 3.9- to 2.9-Ma Waianae Volcano is the older of two volcanoes making up the island of Oahu, Hawaii. Exposed on the volcanic edifice are tholeiitic shield lavas overlain by transitional and alkalic postshield lavas. The postshield \\

Todd K. Presley; John M. Sinton; Malcolm Pringle

1997-01-01

362

Deformation of the Augustine Volcano, Alaska, 1992-2005, measured by ERS and ENVISAT SAR interferometry  

Microsoft Academic Search

The Augustine Volcano is a conical-shaped, active stratovolcano located on an island of the same name in Cook Inlet, about 290 km southwest of Anchorage, Alaska. Augustine has experienced seven significant explosive eruptions-in 1812, 1883, 1908, 1935, 1963, 1976, 1986, and in January 2006. To measure the ground surface deformation of the Augustine Volcano before the 2006 eruption, we applied

C.-W. Lee; Z. Lu; O.-I. Kwoun; J.-S. Won

2008-01-01

363

Tsunami Warning Protocol for Eruptions of Augustine Volcano, Cook Inlet, Alaska  

Microsoft Academic Search

Augustine is an island volcano that has generated at least one tsunami. During its January 2006 eruption coastal residents of lower Cook Inlet became concerned about tsunami potential. To address this concern, NOAA's West Coast\\/ Alaska Tsunami Warning Center (WC\\/ATWC) and the Alaska Volcano Observatory (AVO) jointly developed a tsunami warning protocol for the most likely scenario for tsunami generation

P. Whitmore; C. Neal; D. Nyland; T. Murray; J. Power

2006-01-01

364

Mt. Erebus: A Surprising Volcano: Grades 2-3: text only version  

NSDL National Science Digital Library

This informational text introduces students to Mt. Erebus, a volcano located on Ross Island, just off the coast of Antarctica. Mt. Erebus is the world's southernmost active volcano. The text is written at a grade two through grade three reading level. This is a PDF containing the informational text and a glossary.

Fries-Gaither, Jessica

365

Sizes of Conical Volcanoes  

Microsoft Academic Search

THE shield volcano Mauna Loa in Hawaii is the world's highest mountain, 9,144 m high1, if the portion below sea level is considered in addition to the exposed 4,170 m. Why, then, are the world's highest mountains not land volcanoes? We have investigated the heights and volumes of land volcanoes to try to establish what factors prevent their development to

P. W. Francis; B. M. Abbott

1973-01-01

366

Mud volcanoes on Mars?  

NASA Astrophysics Data System (ADS)

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

Komar, Paul D.

1991-06-01

367

Lifetime of an ocean island volcano feeder zone: constraints from U-Pb dating on coexisting zircon and baddeleyite, and 40/39Ar age determinations, Fuerteventura, Canary Islands  

USGS Publications Warehouse

High-precision isotope dilution - thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon and baddeleyite ages from the PX1 vertically layered mafic intrusion Fuerteventura, Canary Islands, indicate initiation of magma crystallization at 22.10 ± 0.07 Ma. The magmatic activity lasted a minimum of 0.52 Ma. 40Ar/39Ar amphibole dating yielded ages from 21.9 ± 0.6 to 21.8 ± 0.3, identical within errors to the U-Pb ages, despite the expected 1% theoretical bias between 40Ar/39Ar and U-Pb dates. This overlap could result from (i) rapid cooling of the intrusion (i.e., less than the 0.3 to 0.6 Ma 40Ar/39Ar age uncertainties) from closure temperatures (Tc) of zircon (699-988 °C) to amphibole (500-600 °C); (ii) lead loss affecting the youngest zircons; or (iii) excess argon shifting the plateau ages towards older values. The combination of the 40Ar/39Ar and U/Pb datasets implies that the maximum amount of time PX1 intrusion took to cool below amphibole Tc is 0.8 Ma, suggesting PX1 lifetime of 520,000 to 800,000 Ma. Age disparities among coexisting baddeleyite and zircon (22.10 ± 0.07/0.08/0.15 Ma and 21.58 ± 0.15/0.16/0.31 Ma) in a gabbro sample from the pluton margin suggest complex genetic relationships between phases. Baddeleyite is found preserved in plagioclase cores and crystallized early from low silica activity magma. Zircon crystallized later in a higher silica activity environment and is found in secondary scapolite and is found close to calcite veins, in secondary scapolite that recrystallised from plagioclase. close to calcite veins. Oxygen isotope ?18O values of altered plagioclase are high (+7.7), indicating interaction with fluids derived from host-rock carbonatites. The coexistence of baddeleyite and zircon is ascribed to interaction of the PX1 gabbro with CO2-rich carbonatite-derived fluids released during contact metamorphism.

Allibon, James; Ovtcharova, Maria; Bussy, Francois; Cosca, Michael; Schaltegger, Urs; Bussien, Denise; Lewin, Eric

2011-01-01

368

Imaging active volcanes: High resolution 3D seismic tomography of Tenerife Island (Spain)  

Microsoft Academic Search

Tenerife Island internal structure is not well-known. The 3D seismic tomography shows the internal structure of this active volcano with a high resolution. More than 6000 sources and 150 land stations deployed over the island have been used. Tenerife Island is an active volcanic island and it is located in Canary Island's archipelago (Spain). In January of 2007 an active

A. Garcia-Yeguas; V. Sallarès; A. Rietbrock; J. M. Ibáñez

2009-01-01

369

Airborne gravity reveals interior of Antarctic volcano  

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

370

Anatomy of a Volcano  

NSDL National Science Digital Library

This interactive from NOVA Online provides a detailed look at the inner workings of one of the world's most dangerous volcanoes, Nyiragongo in the Democratic Republic of Congo. Users can click on highlighted points on a crossection of the volcano to see photos and read about its features and eruptive products.

371

Chaiten Volcano Still Active  

NSDL National Science Digital Library

This Boston Globe news article shows 12 stunning pictures of the Chaiten Volcano erupting in Chile, its first activity in over 9,000 years. The most recent eruptive phase of the volcano began on May 2, 2008, and is ongoing. The site also has a blog of open, public commentary.

372

Mud Volcanoes on Mars.  

National Technical Information Service (NTIS)

The term mud volcano is applied to a variety of landforms having in common a formation by extrusion of mud from beneath the ground. Although mud is the principal solid material that issues from a mud volcano, there are many examples where clasts up to bou...

P. D. Komar

1991-01-01

373

Groundwater at Mayon, Volcano  

Microsoft Academic Search

Around Mayon Volcano, Philippines, anecdotal evidence and rainfall normalized spring discharge data suggest that the water table 8 km from the summit of the volcano drops prior to eruptions. Residents report that they had to deepen their shallow wells in 1993 (some before and others following the eruption). In some cases they had to dig as far as 5 meters

S. E. Albano; T. Sandoval; R. Toledo

2001-01-01

374

Analysis of the Transport of Volcanic Ash from the July, 2003 Eruption of the Soufriere Hills Volcano on Montserrat to Puerto Rico  

Microsoft Academic Search

The Soufriere Hills Volcano is located on the southern half of the Caribbean island of Montserrat. Montserrat is situated in the northern part of the Lesser Antilles, which is a volcanic island arc formed along the junction of the Atlantic tectonic plate and the Caribbean plate. An eruption of the Soufriere Hills Volcano began in 1995. Periods of small to

J. D. White; L. Roldan; V. Morris

2004-01-01

375

Analysis of the Transport of Volcanic Ash from the July, 2003 Eruption of the Soufrire Hills Volcano on Montserrat to Puerto Rico  

Microsoft Academic Search

The Soufrire Hills Volcano is located on the southern half of the Caribbean island of Montserrat. Montserrat is situated in the northern part of the Lesser Antilles, which is a volcanic island arc formed along the junction of the Atlantic tectonic plate and the Caribbean plate. The Soufrire Hills Volcano began erupting in 1995. On July 12, 2003, a lava-dome

J. White; V. Morris; L. Roldan

2003-01-01

376

Alaska Volcano Observatory  

NSDL National Science Digital Library

This is the homepage of the Alaska Volcano Observatory, a joint program of the United States 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). Users can access current information on volcanic activity in Alaska and the Kamchatka Penninsula, including weekly and daily reports and information releases about significant changes in any particluar volcano. An interactive map also directs users to summaries and activity notifications for selected volcanoes, or through links to webcams and webicorders (recordings of seismic activity). General information on Alaskan volcanoes includes descriptions, images, maps, bibliographies, and eruptive histories. This can be accessed through an interactive map or by clicking on an alphabetic listing of links to individual volcanoes. There is also an online library of references pertinent to Quaternary volcanism in Alaska and an image library.

377

‘New’ Antarctic volcanos  

NASA Astrophysics Data System (ADS)

Two previously unknown volcanos that show evidence o f recent eruptions were discovered in March on the east side of the Antarctic Peninsula, according to the National Science Foundation. The discovery brings to five the number of known active volcanos on the continent.Volcanic debris still covers a large swath of the adjacent Larsen Ice Shelf, pointing to very recent activity. In addition, one of the volcanos was steaming when the discovery was made, reports Oscar Gonzalez-Ferran of the University of Chile at Santiago. He made the discovery while doing a geophysical survey by helicopter of the Antarctic Peninsula. The two volcanos constitute the southernmost extension of the eastern side of the ‘ring of fire,’ a ring of volcanos that is believed to mark the active subduction zone on the periphery of the Pacific Ocean.

378

Performance of type II hybrid ARQ systems using concatenated convolutional and Reed-Solomon codes  

Microsoft Academic Search

Performance approximations for type II hybrid ARQ systems using a concatenation of an inner convolutional code with an outer Reed-Solomon code are presented. The hybrid type II ARQ systems have been shown to be very efficient mechanisms for transmitting data packets. The concatenation of convolutional and Reed-Solomon codes provides one of the most powerful codes available with bandwidth expansion of

Charles F. Bradshaw; Djimitri Wiggert

1990-01-01

379

Improved decoding of Reed-Solomon and algebraic-geometry codes  

Microsoft Academic Search

Given an error-correcting code over strings of length and an arbitrary input string also of length , the list decoding problem is that of finding all codewords within a specified Hamming distance from the input string. We present an improved list decoding algorithm for decoding Reed-Solomon codes. The list decoding problem for Reed-Solomon codes reduces to the following \\

Venkatesan Guruswami; Madhu Sudan

1999-01-01

380

Gravitational tectonics at Mt Haddington, an Antarctic submarine / subglacial volcano  

NASA Astrophysics Data System (ADS)

Mt. Haddington, James Ross Island, Antarctic Peninsula, is a Miocene-recent volcanic complex erupted in marine and ice-shelf conditions. It is 60 km in diameter and 1800 m high, and is surrounded partially by a raised ring of sedimentary and volcanic formations. The sedimentary strata are mainly Cretaceous clay-rich detrital rocks and are up to 6 km thick below the volcano. The volcano is mainly composed of huge lava deltas with <1000m-thick hyaloclastite units under pahoehoe flows. We have analysed the structural deformation around the volcano to assess the role of gravitational loading on sediment deformation and consequent height changes of important paleoenvironmental marker horizons. The west side of the volcano is near the Antarctic peninsular, and the edge of the Weddel sea basin. Structures record an early tilting, then strike-slip deformation parallel to the Peninsula prior to volcanism. Further tilting occurred during volcanism with several 100’s m displacement along bedding-parallel thrusts. The thrusts are intimately linked to transtensional faults and are orientated nearly radial to the volcano. Remarkably little deformation and tilting are observed on the volcano edifice itself, and sediments exposed below the edifice in glacial valleys show only compaction. Thus the volcano has settled into the basin, compressing the substrata, but extruding it only at the edges. Deformation is most intense where the Peninsula constrained the radial expansion. To the east, open the Weddel Sea Basin the deformation is much less intense, but radial expansion is greater.

van Wyk de Vries, B.; Oehler, J.-F.; Smellie, J.

2003-04-01

381

Reed-Solomon coded optically preamplified PPM system  

NASA Astrophysics Data System (ADS)

A Reed-Solomon coded optically preamplified pulse-position modulation system is analyzed. Results are presented at a bit rate of 622 Mbit/s and a wavelength of 1.537 micron, comparing the system with an equivalent on-off nonreturn-to-zero (OOK NRZ) system. The theoretical results demonstrate that the system offers a potential sensitivity of 7 photons/bit, which represents an improvement of 7.5 dB over the equivalent OOK system and is comparable with that of the best coherent systems reported to date.

Cryan, R. A.

1995-06-01

382

A VLSI design of a pipeline Reed-Solomon decoder.  

PubMed

A pipeline structure of a transform decoder similar to a systolic array is 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 coder is regular and simple, and naturally suitable for VLSI implementation. An example illustrating both the pipeline and systolic array aspects of this decoder structure is given for a RS code. PMID:11539661

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

1985-05-01

383

Very long period oscillations of Mount Erebus Volcano  

Microsoft Academic Search

The exposed top of the conduit system at Mount Erebus Volcano, Ross Island, Antarctica, is a convecting lava (magma) lake hosting Strombolian eruptions caused by the explosive decompression of large (up to 5 m radius) gas slugs. Short-period (SP; f >=1 Hz) seismoacoustic eruption seismograms are accompanied by oscillatory very long period (VLP) signals observed in the near field by

R. Aster; S. Mah; P. Kyle; W. McIntosh; N. Dunbar; J. Johnson; M. Ruiz; S. McNamara

2003-01-01

384

Infrasonic Wave Observations of the January 2006 Augustine Volcano Eruptions  

Microsoft Academic Search

The recent Augustine eruptions, from the 11th to the 28th of January 2006, have produced a series of ten infrasonic signals observed at the I53US array*. The eruption times for the signals were provided by the Alaska Volcano Observatory at UAF using a Chaparral microphone present on Augustine Island a few kilometers from the crater. The bearing and distance of

J. V. Olson; C. R. Wilson; S. McNutt; G. Tytgat

2006-01-01

385

The evolution of Nisyros volcano (Greece) in space and time  

Microsoft Academic Search

Nisyros island, the easternmost volcanic centre of the Aegean arc, is an entirely Quaternary volcano made up of a succession of calc-alkaline lava flows and tephra, interbedded with epiclastic layers. It is topped by a quasi-circular caldera, approximately 4 km in diameter and filled in its western part by rhyodacitic domes. Previous studies presumed the existence of a central source

L. Vanderkluysen; A. Volentik; C. Principe; J. Hernandez; J. C. Hunziker

2003-01-01

386

Stability analysis of a collapsing volcano: Stromboli (Italy). First results  

Microsoft Academic Search

During the exceptional volcanic activity occurred on December 2002 and January 2003, Stromboli volcano has shown its tendency to slope instability with landslide phenomena and related tsunami. Those events have intensified the existing threat of new and larger collapses. In the past 13 ka, the Island has experienced four large sector collapses all affecting the NW flank, alternating with periods

T. Apuani; C. Corazzato; A. Tibaldi; A. Cancelli

2003-01-01

387

Microearthquakes at St. Augustine Volcano, Alaska, Triggered by Earth Tides  

Microsoft Academic Search

Microearthquake activity at St. Augustine volcano, located at the mouth of Cook Inlet in the Aleutian Islands, has been monitored since August 1970. Both before and after minor eruptive activity on 7 October 1971, numerous shallow-foci microearthquake swarms were recorded. Plots of the hourly frequency of microearthquakes often show a diurnal peaking of activity. A cross correlation of this activity

F. J. Mauk; J. Kienle

1973-01-01

388

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  

Microsoft Academic Search

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

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

2009-01-01

389

AVO: Alaska Volcano Observatory  

NSDL National Science Digital Library

This site illustrates the Alaska Volcano Observatory's (AVO) objective to monitor Alaska's volcanoes for the purpose of forecasting volcanic activity and alleviating hazards. AVO's seismometers and satellite imagery allow visitors to obtain current information on selected volcanoes. Because AVO is responsible for volcanic emergencies, people in Alaska can visit the Web site to determine their vulnerability. The site also features AVO's research in geological mapping, modeling of magnetic systems, and development of new instrumentation for predication and interpretation of volcanic unrest. Everyone can appreciate the images of past volcanic eruptions.

390

A past giant lateral collapse and present-day flank instability of Fogo, Cape Verde Islands  

Microsoft Academic Search

Fogo island is a large and extremely steepsided oceanic island volcano in the Cape Verde archipelago. It has a large (ca. 9 km across) east facing summit collapse structure, the Monte Amarelo collapse, with a probable volume of at least 150–200 km3. For most of its history the Monte Amarelo volcano had a small but productive central vent complex and

S. J. Day; S. I. N. Heleno da Silva; J. F. B. D. Fonseca

1999-01-01

391

Crustal and mantle influences and U–Th–Ra disequilibrium in andesitic lavas of Ngauruhoe volcano, New Zealand  

Microsoft Academic Search

The andesitic volcano Ngauruhoe, which is located within the Tongariro Volcanic Complex at the southern end of the Taupo Volcanic Zone in North Island, New Zealand, has been constructed over the past 5ka and last erupted in 1975. Nearby Ruapehu volcano has a much longer eruptive history extending back beyond 230kaB.P. The magmas erupted at both volcanoes have been predominantly

Richard C. Price; Simon Turner; Craig Cook; Barbara Hobden; Ian E. M. Smith; John A. Gamble; Heather Handley; Roland Maas; Anja Möbis

2010-01-01

392

Fernandina Volcano's evolved, well-mixed basalts: Mineralogical and petrological constraints on the nature of the Galapagos plume  

Microsoft Academic Search

Fernandina Volcano, the most active of Galapagos volcanoes and the one most directly overlying the Galapagos hotspot, is one of a small number of active, plume-related oceanic island volcanoes with a well-documented recent eruptive record. Whole rock and glass analyses of lava and tephra from all 12 known eruptions from 1958 to the present show them to be evolved (Mg#(=Mg\\/Mg+Fe2+)

James F. Allan; Tom Simkin

2000-01-01

393

Exploring Means of Determining Surface Deformation at Augustine Volcano  

NASA Astrophysics Data System (ADS)

The recent January 2006 eruption of Augustine Volcano followed a nearly a year of increased seismic activity, that has been actively monitored by the Alaska Volcano Observatory (AVO). The eruption has generated a topographical signal that GPS ground stations were able to monitor. This work addresses the question as to which other techniques are able to see this deformation. While we primarily use remotely sensed data, with SAR derived products and techniques as a focus, we also explore the use of ICESAT data. Deformation started in the summer of 2005, with a period of inflation leading up to the January 2006 eruption and which was then followed by a period deflation. The deformation of the flanks of Augustine island was subtle, and GPS stations at the perimeter of the island generally show less that 2cm of total deformation. The summit GPS stations show significantly greater inflation, however these stations were destroyed during the eruption. Traditional INSAR has difficulties when applied to a volcano like Augustine, due to the small area of the island, its large topographic relief, the deposition of ash over the large areas of the island and the long orbital repeat interval of current SAR satellites, all work against the technique. This does not mean however that the outlook is bleak, Permanent Scatterer (PS) INSAR related techniques show great potential. The scientific basis of each technique examined is explained along with the challenges, and limitations that are inherent therein. Deformation results obtained from each method are also presented, and compared with the GPS measurements. The following techniques are examined, 1) INSAR/DINSAR, 2) Permanent Scatterers, 3) Delta K interferometry, 4) ICESAT LIDAR integration, 5) SAR layover/shadow mapping and geometric techniques. Because eruptions at small island volcanoes are common throughout the Aleutian chain, techniques developed for the analysis of this eruption will have great applicability to these and other arc volcanoes.

Lovick, J. T.; Lawlor, O.; Dean, K.; Dehn, J.; Freymueller, J.; Atwood, D.

2006-12-01

394

Pavlof Volcano From Station  

NASA Website

Astronauts aboard the International Space Station (ISS) photographed this striking view of Pavlof Volcano on May 18, 2013. The oblique perspective from the ISS reveals the three dimensional structure of the ash plume, which is often obscured by the ...

395

Volcano Watch Satellite Images  

NSDL National Science Digital Library

The University of Wisconsin's Space Science and Engineering Center displays these satellite images of the world's ten most active volcanoes. Users can view images of the Colima Volcano in Central Mexico or Mount Etna in Sicily, Italy. The latest images are updated every half-hour. Also, a Java animation feature splices together the last four images to show a simulation over a two-hour period.

396

Volcano Monitoring Techniques  

NSDL National Science Digital Library

This site introduces the several methods geologists use to monitor changes in a volcano. These methods assist in forecasting intrusions and eruptions and consist of ground movements, seismicity, gas geochemistry, and geology. As a result of this lesson, students will realize that eruptions have precursor activities, recognize patterns in volcano behavior, and interpret graphical data. This site includes fifteen activities that range from kindergarten to the twelfth grade level and include required material and worksheets.

397

Jun Jaegyu Volcano: A Recently Discovered Alkali Basalt Volcano in Antarctic Sound, Antarctica  

NASA Astrophysics Data System (ADS)

Jun Jaegyu is a young volcanic construct discovered in May 2004 by researchers aboard the National Science Foundation (NSF) vessel Laurence M. Gould (LMG04-04). The volcano is located on the Antarctic continental shelf in Antarctic Sound, approximately 9 km due north of the easternmost point of Andersson Island. Swath bathymetry (NBP01-07) indicates that the volcano stands 700 meters above the seafloor, yet remains 275 meters short of the ocean surface. The seamount lies along a northwest-southeast oriented fault scarp and contains at least 1.5 km3 of volcanic rock. Video recording of the volcano's surface revealed regions nearly devoid of submarine life. These areas are associated with a thermal anomaly of up to 0.052° C higher than the surrounding ocean water. A rock dredge collected ~13 kg of material, over 80% of which was fresh volcanic rock; the remainder was glacial IRD. These observations, along with reports by mariners of discolored water in this region of Antarctic Sound, suggest that the volcano has been recently active. The basalt samples are generally angular, glassy and vesicular. Preliminary petrographic observations indicate that plagioclase, olivine, and clinopyroxene are all present as phenocryst phases, and that small (<1cm) rounded xenoliths are common. A comprehensive study of the volcano's petrography and whole-rock chemistry is currently underway. Jun Jaegyu is the northernmost volcanic center of the James Ross Island Volcanic Group (JRIVG), and the only center in this region of the Antarctic Peninsula with evidence of recent activity. It lies along the boundary between the Late Cenozoic JRIVG and the Upper Paleozoic rocks of the Trinity Peninsula Formation. While the tectonic setting of the region is complex, volcanism appears to be associated with active faults related to within-plate extension.

Hatfield, A.; Bailey, D.; Domack, E.; Brachfeld, S.; Gilbert, R.; Ishman, S.; Krahmann, G.; Leventer, A.

2004-12-01

398

Basaltic island sand provenance  

SciTech Connect

The Hawaiian Islands are an ideal location to study basaltic sand provenance in that they are a series of progressively older basaltic shield volcanoes with arid to humid microclimates. Sixty-two sand samples were collected from beaches on the islands of Hawaii, Maui, Oahu and Kauai and petrographically analyzed. The major sand components are calcareous bioclasts, volcanic lithic fragments, and monomineralic grains of dense minerals and plagioclase. Proportions of these components vary from island to island, with bioclastic end members being more prevalent on older islands exhibiting well-developed fringing reef systems and volcanic end members more prevalent on younger, volcanically active islands. Climatic variations across the island of Hawaii are reflected in the percentage of weathered detritus, which is greater on the wetter, northern side of the island. The groundmass of glassy, basaltic lithics is predominantly black tachylite, with lesser brown sideromelane; microlitic and lathwork textures are more common than holohyaline vitric textures. Other common basaltic volcanic lithic fragments are holocrystalline aggregates of silt-sized pyroxene or olivine, opaque minerals and plagioclase. Sands derived from alkalic lavas are texturally and compositionally indistinguishable from sands derived from tholeiitic lavas. Although Hawaiian basaltic sands overlap in composition with magmatic arc-derived sands in terms of their relative QFL, QmPK and LmLvLs percentages, they are dissimilar in that they lack felsic components and are more enriched in lathwork volcanic lithic fragments, holocrystalline volcanic lithic fragments, and dense minerals.

Marsaglia, K.M. (Univ. of Texas, El Paso, TX (United States). Dept. of Geological Sciences)

1992-01-01

399

CALIPSO Borehole Monitoring Project at Soufriere Hills Volcano, Montserrat, BWI: Overview, and Response of Magma Reservoir to Prodigious Dome Collapse  

Microsoft Academic Search

Project CALIPSO (Caribbean Andesite Lava Island Precision Seismo-geodetic Observatory) aims to investigate the magmatic system at the active Soufriere Hills Volcano (SHV), Montserrat. The collaborative project involves several institutions acting in partnership with the Montserrat Volcano Observatory (MVO), and is funded by NSF with assistance by NERC. SHV remains active after 9 years, displaying cyclic activity on several scales. Many

B. Voight; G. S. Mattioli; A. T. Linde; I. S. Sacks; S. R. Young; P. E. Malin; E. Shalev; D. Hidayat; D. Elsworth; C. Widiwijayanti; V. Miller; N. McWhorter; B. Schleigh; W. Johnston; R. Sparks; J. Neuberg; V. Bass; P. Dunkley; R. Herd; A. Jolly; G. Norton; T. Syers; G. Thompson; C. Williams; D. Williams; A. B. Clarke

2004-01-01

400

The weathering and element fluxes from active volcanoes to the oceans: a Montserrat case study  

Microsoft Academic Search

The eruptions of the Soufrière Hills volcano on Montserrat (Lesser Antilles) from 1995 to present have draped parts of the island in fresh volcaniclastic deposits. Volcanic islands such as Montserrat are an important component of global weathering fluxes, due to high relief and runoff and high chemical and physical weathering rates of fresh volcaniclastic material. We examine the impact of

Morgan T. Jones; Deborah J. Hembury; Martin R. Palmer; Bill Tonge; W. George Darling; Susan C. Loughlin

2011-01-01

401

Volcanology and eruptive styles of Barren Island: an active mafic stratovolcano in the Andaman Sea, NE Indian Ocean  

Microsoft Academic Search

Barren Island (India) is a relatively little studied, little known active volcano in the Andaman Sea, and the northernmost active volcano of the great Indonesian arc. The volcano is built of prehistoric (possibly late Pleistocene) lava flows (dominantly basalt and basaltic andesite, with minor andesite) intercalated with volcaniclastic deposits (tuff breccias, and ash beds deposited by pyroclastic falls and surges),

Hetu C. Sheth; Jyotiranjan S. Ray; Rajneesh Bhutani; Alok Kumar; R. S. Smitha

2009-01-01

402

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

Microsoft Academic Search

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

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

2006-01-01

403